U.S. patent application number 14/343521 was filed with the patent office on 2015-02-12 for protein-containing adhesives, and manufacture and use thereof.
This patent application is currently assigned to Biopolymer Technologies, Ltd.. The applicant listed for this patent is Joseph J. Marcinko, Anthony A. Parker. Invention is credited to Joseph J. Marcinko, Anthony A. Parker.
Application Number | 20150044483 14/343521 |
Document ID | / |
Family ID | 47832579 |
Filed Date | 2015-02-12 |
United States Patent
Application |
20150044483 |
Kind Code |
A1 |
Parker; Anthony A. ; et
al. |
February 12, 2015 |
PROTEIN-CONTAINING ADHESIVES, AND MANUFACTURE AND USE THEREOF
Abstract
The invention provides protein adhesives containing certain
additives and methods of making and using such adhesives. The
protein adhesives contain ground plant meal or an isolated
polypeptide composition obtained from plant biomass in combination
with certain additives, such as an exfoliated clay or partially
exfoliated clay.
Inventors: |
Parker; Anthony A.;
(Newtown, PA) ; Marcinko; Joseph J.; (West
Deptford, NJ) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Parker; Anthony A.
Marcinko; Joseph J. |
Newtown
West Deptford |
PA
NJ |
US
US |
|
|
Assignee: |
Biopolymer Technologies,
Ltd.
Tel Aviv
IL
|
Family ID: |
47832579 |
Appl. No.: |
14/343521 |
Filed: |
September 7, 2012 |
PCT Filed: |
September 7, 2012 |
PCT NO: |
PCT/US12/54124 |
371 Date: |
August 22, 2014 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61532806 |
Sep 9, 2011 |
|
|
|
61567768 |
Dec 7, 2011 |
|
|
|
Current U.S.
Class: |
428/447 ;
156/328; 428/448; 524/704; 524/734 |
Current CPC
Class: |
C09J 175/04 20130101;
C08L 89/00 20130101; B32B 2037/1269 20130101; B32B 7/12 20130101;
C08G 2170/80 20130101; Y10T 428/31663 20150401; C08G 18/36
20130101; C09J 189/00 20130101; C08G 18/6446 20130101; C09J 197/02
20130101; B32B 37/16 20130101; C08L 75/04 20130101; B32B 38/004
20130101; C08G 18/7664 20130101; B32B 21/08 20130101; C08G 18/10
20130101; B32B 2038/0076 20130101; C08L 63/00 20130101; B32B 37/12
20130101; C09J 199/00 20130101; C08H 1/00 20130101; C08L 97/02
20130101; C09J 11/04 20130101; B32B 38/0012 20130101; B32B 2410/00
20130101; B32B 2317/18 20130101; C08L 97/02 20130101; C08L 89/00
20130101; C09J 197/02 20130101; C08L 75/04 20130101; C09J 197/02
20130101; C08L 63/00 20130101; C09J 189/00 20130101; C08L 63/00
20130101; C09J 189/00 20130101; C08L 75/04 20130101 |
Class at
Publication: |
428/447 ;
428/448; 524/734; 524/704; 156/328 |
International
Class: |
C09J 199/00 20060101
C09J199/00; B32B 21/08 20060101 B32B021/08; C09J 175/04 20060101
C09J175/04; B32B 38/00 20060101 B32B038/00; C09J 11/04 20060101
C09J011/04; B32B 37/12 20060101 B32B037/12; B32B 37/16 20060101
B32B037/16; B32B 7/12 20060101 B32B007/12; C09J 189/00 20060101
C09J189/00 |
Claims
1. An adhesive composition comprising: (a) from about 1% to about
90% (w/w) of a reactive prepolymer; (b) ground plant meal in an
amount sufficient to disperse the reactive prepolymer in an aqueous
medium; and (c) at least one first additive selected from the group
consisting of a partially exfoliated clay, an exfoliated clay, an
intercalated clay, cellulose nanoparticles, and a mixture of a
silicone and a terpene compound.
2. The composition of claim 1, wherein the ground plant meal has a
particle size in the range of from about 1 .mu.m to about 200
.mu.m.
3. The composition of claim 1, wherein the ground plant meal has a
particle size in the range of from about 10 .mu.m to about 70
.mu.m.
4. The composition of claim 1, wherein the ground plant meal is
present in an amount sufficient to disperse the reactive prepolymer
in an aqueous medium to form a dispersion or emulsion that exhibits
no phase separation by visual inspection for at least 5 minutes
after mixing the reactive prepolymer with the ground plant
meal.
5. The composition of claim 1, wherein the ground plant meal is
present in an amount such that the viscosity of the adhesive
formulation increases by no more than about 50% within about 20
minutes after mixing the prepolymer and ground plant meal with a
nucleophile.
6-7. (canceled)
8. The composition of claim 1, wherein the ground plant meal is
present in an amount from about 5% to about 35% (w/w) of the
adhesive composition.
9. The composition of claim 1, wherein the ground plant meal is
derived from corn, wheat, sunflower, cotton, rapeseed, canola,
castor, soy, camelina, flax, jatropha, mallow, peanuts, algae,
sugarcane begasse, tobacco, whey, or a combination thereof.
10. An adhesive composition comprising: (a) from about 1% to about
90% (w/w) of a reactive prepolymer; (b) from about 10% to about 98%
(w/w) of an isolated polypeptide composition capable of dispersing
the reactive prepolymer in an aqueous medium; and (c) at least one
first additive selected from the group consisting of a partially
exfoliated clay, an exfoliated clay, an intercalated clay,
cellulose nanoparticles, and a mixture of a silicone and a terpene
compound.
11. A two-part adhesive composition comprising: (a) a first part
(Part A) comprising from about 5% to about 90% (w/w) of a reactive
prepolymer, wherein the reactive prepolymer is a
polyisocyanate-based prepolymer, an epoxy-based prepolymer, or a
combination thereof; (b) a second part (Part B) comprising from
about 10% to about 99% (w/w) of an isolated polypeptide composition
capable of dispersing the reactive prepolymer in an aqueous medium;
and at least one first additive selected from the group consisting
of a partially exfoliated clay, an exfoliated clay, an intercalated
clay, cellulose nanoparticles, and a mixture of a silicone and a
terpene compound.
12. The composition of claim 1, wherein the first additive is a
partially exfoliated clay.
13. The composition of claim 12, wherein the partially exfoliated
clay has a mean particle size of less than about 500 nm.
14. The composition of claim 12, wherein the partially exfoliated
clay is a partially exfoliated smectite.
15. The composition of claim 12, wherein the partially exfoliated
clay is a partially exfoliated montmorillonite.
16. The composition of claim 1, wherein the first additive is an
exfoliated clay.
17. The composition of claim 16, wherein the exfoliated clay has a
mean particle size of less than about 100 nm.
18. The composition of claim 16, wherein the exfoliated clay is an
exfoliated smectite.
19. The composition of claim 16, wherein the exfoliated clay is
exfoliated montmorillonite.
20. The composition of claim 1, wherein the first additive is an
intercalated clay.
21. The composition of claim 20, wherein the intercalated clay is
an intercalated smectite.
22. The composition of claim 20, wherein the intercalated clay is a
smectite that has been intercalated with a quaternary ammonium
compound.
23. The composition of claim 20, wherein the intercalated clay is
an intercalated montmorillonite.
24. The composition of claim 20, wherein the intercalated clay is
montmorillonite intercalated with a
dimethyl-di(C.sub.14-C.sub.18)alkyl ammonium salt.
25. The composition of claim 1, wherein the first additive is a
mixture of a silicone and a terpene compound.
26. (canceled)
27. An adhesive composition comprising: (a) from about 1% to about
90% (w/w) of a reactive prepolymer; (b) ground plant meal in an
amount sufficient to disperse the reactive prepolymer in an aqueous
medium; and (c) at least one first additive selected from the group
consisting of a fire retardant and wood preservative.
28. An adhesive composition comprising: (a) from about 1% to about
90% (w/w) of a reactive prepolymer; (b) from about 10% to about 98%
(w/w) of an isolated polypeptide composition capable of dispersing
the reactive prepolymer in an aqueous medium; and (c) at least one
first additive selected from the group consisting of a fire
retardant and wood preservative.
29. A two-part adhesive composition comprising: (a) a first part
(Part A) comprising from about 5% to about 90% (w/w) of a reactive
prepolymer, wherein the reactive prepolymer is a
polyisocyanate-based prepolymer, an epoxy-based prepolymer, or a
combination thereof; (b) a second part (Part B) comprising from
about 10% to about 99% (w/w) of an isolated polypeptide composition
capable of dispersing the reactive prepolymer in an aqueous medium;
and (c) at least one first additive selected from the group
consisting of a fire retardant and wood preservative, which may be
in Part A, Part B, or both Part A and Part B.
30. The composition of claim 1, wherein the first additive is
present in an amount of from about 0.1% to about 5% w/w of the
adhesive composition.
31. The composition of claim 10, wherein the isolated polypeptide
composition is derived from corn, wheat, sunflower, cotton,
rapeseed, canola, castor, soy, camelina, flax, jatropha, mallow,
peanuts, algae, sugarcane bagasse, tobacco, whey, or a combination
thereof.
32-33. (canceled)
34. The composition of claim 10, wherein the isolated polypeptide
composition comprises one or more of the following features: i. an
amide-I absorption band between about 1620 cm.sup.-1 and 1632
cm.sup.-1 and an amide-II band between approximately 1514 cm.sup.-1
and 1521 cm.sup.-1, as determined by solid state Fourier Transform
Infrared Spectoscopy (FTIR), ii. a prominent 2.degree. amide N--H
stretch absorption band centered at about 3272 cm.sup.-1, as
determined by solid state FTIR, iii. an average molecular weight of
between about 600 and about 2,500 Daltons, iv. two protonated
nitrogen clusters defined by .sup.15N chemical shift boundaries at
about 86.2 ppm and about 87.3 ppm, and .sup.1H chemical shift
boundaries at about 7.14 ppm and 7.29 ppm for the first cluster,
and .sup.1H chemical shift boundaries at about 6.66 ppm and 6.81
ppm for the second cluster, as determined by solution state,
two-dimensional proton-nitrogen coupled NMR, and v. is capable of
dispersing an oil-in-water or water-in-oil to produce a homogeneous
emulsion that is stable for least 5 minutes.
35. (canceled)
36. The composition of claim 1, further comprising a formaldehyde
scavenging agent.
37. The composition of claim 36, wherein the formaldehyde
scavenging agent is H.sub.2NC(O)NH.sub.2.
38. (canceled)
39. The composition of claim 1, wherein the reactive prepolymer is
a polyisocyanate-based prepolymer, an epoxy-based prepolymer, a
latex-based prepolymer, a latex prepolymer, or a combination
thereof.
40. The composition of claim 1, wherein the reactive prepolymer is
a polyisocyanate-based prepolymer.
41. The composition of claim 39, wherein the polyisocyanate-based
prepolymer is an organic polyisocyanate; or a reaction product
between an organic polyisocyanate and a polypeptide, a polyol, an
amine based polyol, an amine containing compound, a hydroxy
containing compound, or a combination thereof.
42. The composition of claim 39, wherein the polyisocyanate-based
prepolymer is a polymer comprising a terminal reactive isocyanate
group.
43-45. (canceled)
46. The composition of claim 1, wherein the reactive prepolymer is
an organic polyisocyanate selected from the group consisting of
polymeric diphenylmethane diisocyanate (PMDI),
4,4'-methylenediphenyl, diisocyanate (4,4'-MDI),
2,4-methylenediphenyl, diisocyanate (2,4-MDI), or a combination
thereof.
47. The composition of claim 1, further comprising water.
48. The composition of claim 47, wherein the water is present in an
amount from about 30% (w/w) to about 60% (w/w) of the adhesive
composition.
49-53. (canceled)
54. The composition of claim 1, wherein the composition comprises a
partially exfoliated clay, silicone, and a terpene compound.
55. The composition of claim 1, wherein the composition comprises
silicone, limonene, and partially exfoliated montmorillonite
intercalated with a dimethyl-di(C.sub.14-C.sub.18)alkyl ammonium
salt.
56. A solid binder composition formed by curing a composition of
claim 1.
57. A method of bonding a first article to a second article
comprising: (a) depositing on a surface of the first article the
adhesive composition of claim 1 thereby to create a binding area;
and (b) contacting the binding surface with a surface of the second
article thereby to bond the first article to the second
article.
58. The method of claim 57, further comprising the step of, after
step (b), permitting the adhesive composition to cure.
59. A method of producing a composite material comprising: (a)
combining a first article and a second article with the adhesive
composition of claim 1 to produce a mixture; and (b) curing the
mixture produced by step (a) to produce the composite material.
60. The method of claim 59, wherein the curing comprises applying
pressure, heat or both pressure and heat to the mixture.
61. The method of claim 60, wherein the first article, the second
article or both the first and second articles are lignocellulosic
materials, or composite materials containing lignocellulosic
material.
62. (canceled)
63. An article produced by the method of claim 57.
64. An article comprising two or more components bonded together
using the adhesive composition of claim 1.
65-66. (canceled)
67. An article produced using the adhesive composition of claim
1.
68. The article of claim 67, wherein the article is a
composite.
69. The article of claim 68, wherein the composite is a random
non-oriented homogeneous composite, an oriented composite, or a
laminated composite
70. The article of claim 68, wherein the composite is chip board,
particle board, fiber board, oriented strand board, plywood,
laminated veneer lumber, glulam, laminated whole lumber, laminated
composite lumber, composite wooden I-beams, medium density
fiberboard, high density fiberboard, extruded wood, or
fiberglass.
71-74. (canceled)
75. An adhesive composition comprising: (a) from about 5% to about
40% (w/w) of a reactive prepolymer; (b) from about 5% to about 30%
(w/w) ground plant meal; (c) from about 1% to about 40% (w/w) of a
dry powder fire retardant; and (d) from about 30% to about 70%
(w/w) water.
76. The adhesive composition of claim 75, wherein the reactive
prepolymer is polymeric diphenylmethane diisocyanate.
77. The adhesive composition of claim 76, wherein the ground plant
meal is ground canola meal.
78. The adhesive composition of claim 77, wherein the dry powder
fire retardant is present in an amount ranging from 20% to about
35% (w/w) of the adhesive composition.
79. The adhesive composition of claim 78, wherein the dry powder
fire retardant is colemanite.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application claims the benefit of and priority to U.S.
Provisional Patent Application Ser. No. 61/532,806, filed Sep. 9,
2011, and to U.S. Provisional Patent Application Ser. No.
61/567,768, filed Dec. 7, 2011, the contents of each of which are
hereby incorporated by reference.
FIELD OF THE INVENTION
[0002] The invention provides protein adhesives containing certain
additives, and methods of making and using such adhesives. The
protein adhesives contain an additive and ground plant meal or an
isolated polypeptide composition obtained from plant biomass, and
are useful in the preparation of various wood products.
BACKGROUND
[0003] Adhesive compositions are used extensively in the wood
products industry to make composites such as chipboard, fiberboard,
and related composite wood products. Adhesive compositions are also
used to make engineered lumber composites. Traditionally, these
composites have been made using a urea formaldehyde (UF) resin or a
phenol formaldehyde (PF) resin. More recently, polymeric
methylenediphenyl diisocyanate (PMDI) has been used to make these
composites. UF resin, PF resin and PMDI are made from petroleum
feedstock and can require high temperature conditions to facilitate
cure. For example, heating the resin-wood mixture to temperatures
exceeding 100.degree. C., and often 200.degree. C., while exerting
pressure on the mixture in order to form the composite. These
high-temperature conditions can be problematic in certain
structural (or engineered) lumber applications when UF and PF
resins are used because it is often impractical to reach such high
temperatures necessary to cure the adhesive due to the large size
and inadequate heat transfer throughout the engineered wood
composite. The high-temperature conditions are generally less
problematic for PMDI resins because alternative heat transfer
mechanisms can be used. However, PMDI resins are more costly that
UF and PF resins. Thus, lower resin loadings must be used in the
composite to make these composites on economical terms, but the
lower loading of resin can itself be problematic for certain prior
PMDI-based resins because it can be difficult to efficiently
disperse small quantities of resin in the wood.
[0004] In response to the need for environmentally friendly
adhesive compositions, there has been renewed interest in using
certain soy products to form adhesive compositions. However, there
are multiple challenges in developing an adhesive composition from
soy products. For example, the adhesive composition when cured to
form a binder must have sufficient bond strength. The adhesive
composition when cured to form a binder should, for certain
applications, be sufficiently resistant to moisture. Another
challenge is that the adhesive composition must have sufficient pot
life so that it does not cure before being applied to components in
the wood product. It is also important that the soy product be
capable of production on large scale at economically feasible
terms, and that it is amenable to cure conditions used to form the
wood product.
[0005] Various reports describe efforts at developing an adhesive
composition using certain soy products. U.S. Patent Application
publication 2008/0021187 describes an adhesive composition
containing urea-denatured soy flour. U.S. Pat. No. 7,416,598
describes an adhesive composition containing a protein ingredient
and a modifying ingredient. Zhong and coworkers describe an
adhesive composition containing certain soy protein material that
has been modified. Zhong et al. in J. Appl. Polym. Sci. (2007) 103:
2261-2270. Yet, despite these efforts, the need exists for an
environmentally friendly adhesive composition that meets the
demands for widespread industrial application in the wood products
industry.
[0006] The present invention addresses this need, and provides
other related advantages.
SUMMARY OF THE INVENTION
[0007] The invention provides protein adhesive compositions,
methods of making and using such adhesives, and articles prepared
using such adhesives. The protein adhesive compositions contain a
reactive prepolymer, at least one additive, and a protein component
that is ground plant meal or an isolated polypeptide composition
obtained from plant biomass. The additives impart improved
performance properties, such as improved resistance to moisture,
enhanced toughness, improved resistance to distortion due to heat,
and/or altered rheological properties. Exemplary additives include
a partially exfoliated clay, an exfoliated clay, an intercalated
clay, cellulose nanoparticles, and a mixture of a silicone and a
terpene compound. The protein component contributes to the
performance of the adhesive in several aspects, such as aiding
dispersion of the reactive prepolymer, protecting the reactive
prepolymer from premature reaction with nucleophiles, and
facilitating preparation of stable emulsions/dispersions of
exfoliated clays and partially exfoliated clays. The protein
adhesive compositions are useful for preparing wood composites,
such as particle board.
[0008] Accordingly, one aspect of the invention provides an
adhesive composition comprising: (a) from about 1% to about 90%
(w/w) of a reactive prepolymer; (b) ground plant meal in an amount
sufficient to disperse the reactive prepolymer in an aqueous
medium; and (c) at least one first additive selected from the group
consisting of a partially exfoliated clay, an exfoliated clay, an
intercalated clay, cellulose nanoparticles, and a mixture of a
silicone and a terpene compound. The amount of ground plant meal in
the adhesive composition can be adjusted to meet the performance
properties desired for a particular application. For example, the
amount of ground plant meal can be adjusted to provide an amount
sufficient to disperse the reactive prepolymer in an aqueous
medium. Alternatively, or in addition, the amount of ground plant
meal can be adjusted to provide an adhesive composition where no
more than about 1 mole percent, 5 mole percent, or 10 mole percent
of the prepolymer undergoes reaction with a nucleophile within one
minute after the reactive prepolymer contacts the nucleophile. The
amount of prepolymer that undergoes reaction with a nucleophile can
be determined by measuring the rate at which the prepolymer
undergoes reaction with the nucleophile at ambient temperature in a
sample of the adhesive composition.
[0009] Particle size of the ground plant meal can be adjusted to
optimize performance properties of the adhesive composition for a
particular application. For example, in certain embodiments, the
ground plant meal has a particle size in the range of from 1 .mu.m
to about 200 .mu.m, from about 10 .mu.m to about 90 .mu.m, or from
about 10 .mu.m to about 70 .mu.m.
[0010] As noted above, the adhesive composition can be
characterized according to whether the ground plant meal is present
in an amount sufficient to disperse the reactive prepolymer. In
certain embodiments, the ground plant meal is present in an amount
sufficient to disperse the reactive prepolymer in an aqueous medium
to form a dispersion or emulsion that exhibits no phase separation
by visual inspection for at least 5 minutes after mixing the
reactive prepolymer with the ground plant meal. In certain other
embodiments, the dispersion or emulsion exhibits substantially no
phase separation by visual inspection for at least 10, 15, 20, 25,
or 30 minutes, or even 1, 2, 3, 4, 5, or 6 hours or more after
mixing the ground plant meal with the reactive prepolymer.
[0011] The adhesive composition also can be characterized according
to changes in viscosity over time. For example, in certain
embodiments, the ground plant meal is present in an amount such
that the viscosity of the adhesive formulation increases by no more
than about 25% within about 20 minutes, or no more than about 50%
within about 20 minutes, after mixing the prepolymer and ground
plant meal with a nucleophile.
[0012] In the foregoing aspects, the nucleophile can be water, a
urea, a hydroxyl-containing compound, an amine-containing compound,
an amide-containing compound, a sulfhydryl-containing compound, or
a mixture thereof. In certain other embodiments, the nucleophile is
urea. In certain other embodiments, the nucleophile is glycerin,
water, or both.
[0013] Further yet, the adhesive composition can be characterized
according to the weight percent of the ground plant meal in the
composition. In certain embodiments, the ground plant meal is
present in an amount from about 5% to about 35% (w/w) of the
adhesive composition.
[0014] Ground plant meal can be derived from renewable agricultural
biomass. Exemplary agricultural biomass includes corn, wheat,
sunflower, cotton, rapeseed, canola, castor, soy, camelina, flax,
jatropha, mallow, peanuts, algae, sugarcane bagasse, tobacco, whey,
or a combination thereof. In certain embodiments, the ground plant
meal is soy meal or canola meal.
[0015] The adhesive composition may be in the form of a liquid or
particulate solid. In certain embodiments, the composition is in
the form of a liquid.
[0016] The adhesive composition can be further characterized
according to the product formed upon curing the adhesive. For
example, in certain embodiments, upon curing, the composition forms
a solid binder composition. The solid binder composition may have
one or more of the following features: (i) it comprises from about
5% to about 75% (w/w) of ground plant meal; (ii) it comprises from
about 5% to about 75% (w/w) of a polymeric material formed from the
reactive prepolymer; and (iii) it is a thermoset solid. In certain
other embodiments, the solid binder composition has one or more of
the following features: (i) it comprises from about 5% to about 65%
(w/w) of ground plant meal; (ii) it comprises from about 5% to
about 65% (w/w) of a polymeric material formed from the reactive
prepolymer; and (iii) it is a thermoset solid.
[0017] A variety of nucleophiles can react with a prepolymer. The
nucleophile may be an additive or a component of the ground meal.
In certain embodiments, the nucleophile is water, an urea, a
hydroxyl-containing compound, an amine-containing compound, an
amide-containing compound, a sulfhydryl-containing compound, or a
mixture thereof. In certain embodiments, the nucleophile is urea,
i.e., H.sub.2NC(O)NH.sub.2.
[0018] Another aspect of the invention provides an adhesive
composition comprising: (a) from about 1% to about 90% (w/w) of a
reactive prepolymer; and (b) from about 10% to about 98% (w/w) of
an isolated polypeptide composition capable of dispersing the
reactive prepolymer in an aqueous medium, for example, water or a
water-based solution; and (c) at least one first additive selected
from the group consisting of a partially exfoliated clay, an
exfoliated clay, an intercalated clay, cellulose nanoparticles, and
a mixture of a silicone and a terpene compound. The water-based
solution can contain a plurality of dissolved components and/or can
contain a dispersed or emulsified latex polymer. In certain
embodiments, the adhesive composition comprises from about 5% to
about 90% (w/w) of a reactive prepolymer.
[0019] In certain circumstances, the reactive prepolymer is a
polyisocyanate-based prepolymer, an epoxy-based prepolymer, a latex
prepolymer, or is a combination thereof. Depending upon the
components of the adhesive, the prepolymer and isolated polypeptide
composition can be mixed and stored as a mixture until use (for
example, when an activator or catalyst is added to the mixture, or
where the mixture is stored under conditions so that curing does
not occur). Alternatively, when no other additives are needed to
initiate a reaction between the reactive prepolymer and the
isolated polypeptide composition, the reactive prepolymer and the
polypeptide composition are mixed immediately prior to use.
[0020] Another aspect of the invention provides a two-part adhesive
composition comprising: (a) a first part (Part A) comprising from
about 5% to about 90% (w/w) of a reactive prepolymer, wherein the
reactive prepolymer is a polyisocyanate-based prepolymer, an
epoxy-based prepolymer, or a combination thereof; and (b) a second
part (Part B) comprising (i) from about 10% to about 99% (w/w) of
an isolated polypeptide composition capable of dispersing the
reactive prepolymer in an aqueous medium, and (ii) at least one
first additive selected from the group consisting of a partially
exfoliated clay, an exfoliated clay, an intercalated clay,
cellulose nanoparticles, and a mixture of a silicone and a terpene
compound.
[0021] Depending upon the composition of Part A and Part B, Parts A
and B are mixed immediately prior to use. In one embodiment, the
adhesive, when cured, comprises from about 1% to about 95% (w/w) of
non-volatile moieties of Part A and from about 5% to about 99%
(w/w) of non-volatile moieties of Part B. Furthermore, depending
upon the application and functionality of the adhesive composition,
the weight ratio of solids in Part B to the prepolymer can be in
the range of from 100:0.1 to 0.1:100.
[0022] The particular first additive in the adhesive composition
may be selected in order to achieve certain performance properties.
For example, in certain embodiments, the at least one first
additive is partially exfoliated clay. In certain other
embodiments, the at least one first additive is an exfoliated clay.
In certain other embodiments, the at least one first additive is an
intercalated clay. In certain other embodiments, the at least one
first additive is cellulose nanoparticles. In certain other
embodiments, the at least one first additive is a mixture of a
silicone and a terpene compound. In certain embodiments, the
adhesive composition comprises a mixture of two or more of the
aforementioned additives. For example, in certain embodiments, the
adhesive composition comprises an intercalated clay, silicone, and
a terpene compound. In certain other embodiments, the adhesive
composition comprises silicone, limonene, and montmorillonite
intercalated with a dimethyl-di(C.sub.14-C.sub.18)alkyl ammonium
salt. In certain other embodiments, the adhesive composition
comprises a partially exfoliated clay, silicone, and a terpene
compound. In certain other embodiments, the adhesive composition
comprises silicone, limonene, and partially exfoliated
montmorillonite intercalated with a
dimethyl-di(C.sub.14-C.sub.18)alkyl ammonium salt.
[0023] Another aspect of the invention provides an adhesive
composition comprising (a) from about 1% to about 90% (w/w) of a
reactive prepolymer; (b) ground plant meal in an amount sufficient
to disperse the reactive prepolymer in an aqueous medium; and (c)
at least one first additive selected from the group consisting of a
fire retardant and wood preservative.
[0024] Another aspect of the invention provides an adhesive
composition comprising (a) from about 1% to about 90% (w/w) of a
reactive prepolymer; (b) from about 10% to about 98% (w/w) of an
isolated polypeptide composition capable of dispersing the reactive
prepolymer in an aqueous medium; and (c) at least one first
additive selected from the group consisting of a fire retardant and
wood preservative.
[0025] Another aspect of the invention provides a two-part adhesive
composition comprising (a) a first part (Part A) comprising from
about 5% to about 90% (w/w) of a reactive prepolymer, wherein the
reactive prepolymer is a polyisocyanate-based prepolymer, an
epoxy-based prepolymer, or a combination thereof; (b) a second part
(Part B) comprising from about 10% to about 99% (w/w) of an
isolated polypeptide composition capable of dispersing the reactive
prepolymer in an aqueous medium; and (c) at least one first
additive selected from the group consisting of a fire retardant and
wood preservative, which may be in Part A, Part B, or both Part A
and Part B.
[0026] The adhesive composition may further comprise a formaldehyde
scavenging agent. The formaldehyde scavenging agent is a compound
that will undergo reaction with formaldehyde, particularly
formaldehyde generated from wood particles used in preparation of a
composite. A variety of formaldehyde scavenging agents are known in
the art and are contemplated to be amenable for use in the present
invention. Further description of formaldehyde scavenging agents is
described herein below.
[0027] Another aspect of the invention provides an adhesive
composition, comprising: (a) from about 5% (w/w) to about 40% (w/w)
of a reactive prepolymer; (b) from about 5% (w/w) to about 30%
(w/w) ground plant meal; (c) from about 1% (w/w) to about 40% (w/w)
of a dry powder fire retardant; and (d) from about 30% (w/w) to
about 70% (w/w) water.
[0028] In each of the aspects of the invention, the isolated
polypeptide composition can be derived from renewable agricultural
biomass. Starting material for the isolated polypeptide
composition, which can be a meal or a protein isolate, can be
derived from one or more of corn, wheat, sunflower, cotton,
rapeseed, canola, castor, soy, camelina, flax, jatropha, mallow,
peanuts, algae, sugarcane bagasse, tobacco, whey, or a combination
thereof. The isolated polypeptide composition can be isolated by
extraction under neutral or basic conditions, by enzyme digestion,
or a combination thereof. Furthermore, in certain embodiments, the
isolated polypeptide composition is substantially free of primary
amines, carboxylic acids, amine salts, and carboxylate salts.
[0029] In certain embodiments, the adhesive composition is
characterized in that, upon curing, the composition forms a solid
binder composition comprising from about 1% to about 50% (w/w),
from about 1% to about 30% (w/w), from about 1% to about 20% (w/w),
from about 2% to about 50% (w/w), from about 2% to about 30% (w/w),
from about 5% to about 50% (w/w), from about 5% to about 30% (w/w),
from about 5% to about 20% (w/w), from about 10% to about 50%
(w/w), from about 10% to about 30% (w/w), or from about 10% to
about 20% (w/w) of formaldehyde scavenging agent. In certain other
embodiments, the adhesive composition is characterized in that,
upon curing, the composition forms a solid binder composition
comprising from about 1% to about 50% (w/w) of formaldehyde
scavenging agent. In still other embodiments, the adhesive
composition is characterized in that, upon curing, the composition
forms a solid binder composition comprising from about 2% to about
30% (w/w) of formaldehyde scavenging agent.
[0030] In certain other embodiments, the adhesive composition is
characterized in that, upon curing, the composition forms a solid
binder composition comprising from about 0.1% to about 50% (w/w),
from about 0.1% to about 30% (w/w), from about 0.1% to about 20%
(w/w), from about 0.2% to about 50% (w/w), from about 0.2% to about
30% (w/w), from about 0.5% to about 50% (w/w), from about 0.5% to
about 30% (w/w), from about 0.5% to about 20% (w/w), from about 1%
to about 50% (w/w), from about 1% to about 30% (w/w), or from about
1% to about 20% (w/w) of formaldehyde scavenging agent. In certain
other embodiments, the adhesive composition is characterized in
that, upon curing, the composition forms a solid binder composition
comprising from about 0.1% to about 50% (w/w) of formaldehyde
scavenging agent. In still other embodiments, the adhesive
composition is characterized in that, upon curing, the composition
forms a solid binder composition comprising from about 1% to about
30% (w/w) of formaldehyde scavenging agent.
[0031] The quantity and chemical features of the reactive
prepolymer impact the performance properties of the adhesive
composition. Thus, the amount and identity of the reactive
prepolymer can be selected in order to optimize performance
properties of the adhesive composition for use in a particular
application. For example, in certain embodiments and unless
specified otherwise, the reactive prepolymer can be a
polyisocyanate-based prepolymer, an epoxy-based prepolymer, a
latex-based prepolymer, a latex prepolymer, or a combination
thereof. In certain other embodiments, the reactive prepolymer is a
polyisocyanate-based prepolymer. In certain embodiments, the
polyisocyanate-based prepolymer is an organic polyisocyanate; or a
reaction product between an organic polyisocyanate and, for
example, a polypeptide, a polyol, an amine based polyol, an amine
containing compound, a hydroxy containing compound, or a
combination thereof. In still other embodiments, the
polyisocyanate-based reactive prepolymer is a polymer comprising a
terminal reactive isocyanate group.
[0032] The epoxy-based prepolymer can be an epoxide containing
compound. Alternatively, the epoxy-based prepolymer can be a
reaction product between an epoxy and, for example, a polypeptide,
a polyol, an amine based polyol, an amine containing compound, a
hydroxy containing compound, or a combination thereof. The epoxy
can be selected from the group consisting of a diglycidyl ether of
bisphenol-A, a diglycidyl ether of bisphenol-A alkoxylate, an epoxy
novolac resin, expoxidized soy oil, epoxidized linseed oil,
epichlorohydrin, a glycidyl ether-type epoxy resin derived from a
polyphenol by reaction with epichlorohydrin, and a combination
thereof.
[0033] The polyol in the prepolymer composition can be an amine
alkoxylate, polyoxypropylene glycol, polyoxyethylene glycol,
polytetramethylene glycol, polyethylene glycol, propylene glycol,
propane diol, glycerin, or a mixture thereof.
[0034] In each of the foregoing aspects of the invention, the
organic polyisocyanate can be selected from the group consisting of
polymeric diphenylmethane diisocyanate (PMDI),
4,4'-methylenediphenyl, diisocyanate (4,4'-MDI),
2,4-methylenediphenyl, diisocyanate (2,4-MDI), and a combination of
the foregoing.
[0035] The adhesive compositions may further comprise water. In
certain embodiments, water is present in an amount from about 30%
(w/w) to about 60% (w/w) of the adhesive composition. In certain
other embodiments, water is present in an amount from about 20%
(w/w) to about 35% (w/w) of the adhesive composition. The amount of
water used in the adhesive composition may be characterized
relative to the amount of wood in the final composite. For example,
in certain embodiments, the total weight percent of water from the
adhesive composition used to form a composite is from about 2% to
about 18% by weight of the wood in the composite on an oven dried
basis, or from about 2% to about 13% by weight of the wood in the
composite on an oven dried basis, or from about 2% to about 8% by
weight of the wood in the composite on an oven dried basis.
[0036] When the adhesive composition comprises a catalyst, the
catalyst can be a primary amine, a secondary amine, a tertiary
amine, an organometallic compound, or a combination thereof, as
further described in the detailed description.
[0037] In each of the foregoing aspects of the invention, the
isolated polypeptide composition can be further characterized
according to its polydispersity index (PDI). For example, in
certain embodiments the isolated polypeptide composition has a PDI
of between about 1 and 1.15. In certain other embodiments, the
isolated polypeptide composition has a polydispersity index (PDI)
of between about 1 and 1.75, or between about 1 and 3.
[0038] In each of the foregoing aspects of the invention, the
adhesive composition may further comprise an second additive.
Exemplary second additives include a polyol, glycerin, corn syrup,
a poly(C.sub.2-C.sub.6)alkylene, mineral oil, an
ethylene/propylene/styrene copolymer, a butylene/ethylene/styrene
copolymer, soy oil, castor oil, or a mixture of one or more of the
foregoing. In certain embodiments, the second additive is
polybutene. In certain other embodiments, the second additive is a
fire retardant or wood preservative. In certain embodiments, the
polybutene has a weight average molecular weight of from about 200
g/mol to about 20,000 g/mol, from about 200 g/mol to about 10,000
g/mol, from about 200 g/mol to about 5,000 g/mol, from about 200
g/mol to about 2,000 g/mol, from about 200 g/mol to about 1,000
g/mol, from about 500 g/mol to about 2,000 g/mol, or from about 500
g/mol to about 1,000 g/mol. In certain other embodiments, the
additive is a polyol, such as glycerin, which permits less water to
be used in the adhesive composition. In yet other embodiments, the
additive is an agent that improves moisture-resistance, a
composite-release promoter, a pH modulator, or an antimicrobial
agent. In yet other embodiments, the additive is an agent that
improves moisture-resistance, a composite-release promoter, a pH
modulator, tacking agent, or an antimicrobial agent.
[0039] In another aspect, the invention provides a solid binder
composition formed by curing an adhesive composition described
herein.
[0040] In another aspect, the invention provides a method of
bonding a first article to a second article. The method comprises
the steps of (a) depositing on a surface of the first article any
one of the foregoing adhesive compositions thereby to create a
binding area; and (b) contacting the binding surface with a surface
of the second article thereby to bond the first article to the
second article. The method optionally also comprises the step of,
after step (b), permitting the adhesive composition to cure, which
can be facilitated by the application of pressure, heat or both
pressure and heat.
[0041] In another aspect, the invention provides a method of
producing a composite material. The method comprises the steps of
(a) combining a first article and a second article with any one of
the foregoing adhesive compositions to produce a mixture; and (b)
curing the mixture produced by step (a) to produce the composite
material. The curing can comprise applying pressure, heat or both
pressure and heat to the mixture.
[0042] In certain embodiments, the first article, the second
article or both the first and second articles are lignocellulosic
materials, or composite materials containing lignocellulosic
material. The first article, the second article or both the first
and second articles can comprise a metal, a resin, a ceramic, a
polymer, a glass or a combination thereof. The first article, the
second article, or both the first article and the second article
can be a composite. In addition, the invention provides an article
produced by each of the foregoing methods of manufacture.
[0043] In addition, the invention provides an article comprising
two or more components bonded together using one or more of the
adhesive compositions described herein. The bonded components can
be selected from the group consisting of paper, wood, glass, metal,
fiberglass, wood fiber, ceramic, ceramic powder, plastic (for
example, a thermoset plastic), and a combination thereof. In
certain other embodiments, the bonded components can be selected
from the group consisting of paper, wood, glass, metal, fiberglass,
wood fiber, ceramic, ceramic powder, sand, plastic (for example, a
thermoset plastic), and a combination thereof. The invention
provides an article (for example, a composite material, laminate,
or a laminate containing composite material) produced using one or
more of the adhesive compositions described herein.
[0044] The composite material can be chip board, particle board,
fiber board, plywood, laminated veneer lumber, glulam, laminated
whole lumber, laminated composite lumber, composite wooden I-beams,
medium density fiberboard, high density fiberboard, orientated
strand board, extruded wood, or fiberglass. The composite can be a
thermosetting composite or a thermoplastic composite.
[0045] In certain embodiments, the article is a composite, such as
a random non-oriented homogeneous composite, an oriented composite,
or a laminated composite.
[0046] In certain embodiments, the article comprises a
lignocellulosic component. Furthermore, the article can comprise
paper, wood, glass, fiberglass, wood fiber, ceramic, ceramic
powder, or a combination thereof. In certain embodiments, the
adhesive can comprise an organic polyisocyanate, for example, in an
amount ranging from about 5% to about 30% (w/w), from about 5% to
about 20% (w/w), from about 5% to about 15% (w/w), or from about
10% to about 20% (w/w) of the adhesive composition. In certain
other embodiments, the adhesive can comprise from about 30% to
about 70% (w/w) of an organic polyisocyanate.
[0047] The article can further comprise a polyurethane. In certain
embodiments, the polyurethane comprises from about 1% to about 25%
(w/w) of the article, from about 1% to about 15% (w/w), from about
5% to about 20% (w/w), from about 5% to about 15% (w/w), or from
about 5% to about 10% (w/w) of the article. In certain embodiments,
the polyurethane that comprises from about 1% to about 25% (w/w) of
the article.
[0048] In certain embodiments, the article is a particle board
composite. The amount of wood and adhesive composition used to
prepare the particle board composite can be adjusted to optimize
the performance properties of the particle board for different
applications (e.g., outdoor use where increased water resistance is
desirable). In certain embodiments, the composite comprises at
least about 80% (w/w) wood, at least about 90% (w/w) wood, at least
about 95% (w/w) wood, or at least about 98% (w/w) wood. In certain
other embodiments, the composite has one or more of the following
features: (i) it comprises from about 0.1% to about 15% (w/w) of
ground plant meal or isolated polypeptide composition; (ii) it
comprises from about 0.1% to about 10% (w/w) of a polymeric
material formed by reaction of the prepolymer; (iii) it comprises
from about 0.1% to about 10% (w/w) of formaldehyde scavenging
agent; and (iv) it comprises from about 0.1% to about 10% (w/w) of
a diluent.
[0049] Depending upon the adhesive used, the resulting article can
have one or more of the following features: the article is moisture
resistant; the article remains intact after boiling in water for 5
minutes; two or more components of the article remain bonded after
boiling in water for 5 minutes; the article, when boiled in water
for 5 minutes, displays less than a 20% increase in volume relative
to the article prior to exposure to the water; and when the article
(for example, a composite material, laminate, or a laminate
containing a composite material) contains a lignocellulosic
material in the composite material or laminate, the article
exhibits no less than 50%, optionally no less than 75%, cohesive
failure of the lignocellulosic component when the article is placed
under a loading stress sufficient to break the article. In certain
embodiments, the article exhibits no less than 50% cohesive failure
of the lignocellulosic component when the article is placed under a
loading stress sufficient to break the article.
[0050] These and other aspects and features of the invention are
described in the following detailed description and claims.
BRIEF DESCRIPTION OF THE DRAWINGS
[0051] The foregoing and other objects, features and advantages of
the invention will become apparent from the following description
of preferred embodiments, as illustrated in the accompanying
drawings. Like referenced elements identify common features in the
corresponding drawings. The drawings are not necessarily to scale,
with emphasis instead being placed on illustrating the principles
of the present invention, in which:
[0052] FIG. 1 is a flow chart showing adhesives that can be
produced using the protein components (i.e., ground plant meal or
isolated polypeptide composition) described herein;
[0053] FIG. 2 is a flow chart showing the steps of an exemplary
method for producing isolated polypeptide compositions useful in
the practice of the invention;
[0054] FIG. 3 is a graph showing the relationship between the
concentration of the water-insoluble/water-dispersible protein and
the performance of an adhesive (or binder) produced using the
protein;
[0055] FIG. 4 shows overlaid solid state FTIR spectra for
water-soluble and water-insoluble protein fractions isolated from
digested castor lot 5-90;
[0056] FIG. 5 shows solid state FTIR spectra of isolated
water-soluble and water-insoluble fractions from digested castor,
where the carbonyl amide region is expanded;
[0057] FIG. 6 shows solid state FTIR spectra of isolated
water-soluble and water-insoluble fractions from digested castor
where the N--H stretching region is expanded;
[0058] FIG. 7 shows overlaid solid state FTIR spectra of isolated
fractions from castor protein (lot 5-94), showing an expansion of
the carbonyl amide region (water-soluble fraction, and
water-insoluble/water-dispersible fraction);
[0059] FIG. 8 shows the solid state FTIR spectra of isolated
water-soluble and water-insoluble fractions from castor protein
(lot 5-94), where the N--H and O--H stretch regions are
expanded;
[0060] FIG. 9 shows overlaid solid state FTIR spectra of the
isolated water-insoluble/water-dispersible fractions from castor
protein (lot 5-94) and from enzyme digested castor (lot 5-90);
[0061] FIG. 10 shows overlaid solid state FTIR spectra of isolated
water-soluble and water-insoluble fractions from digested soy,
where the carbonyl amide region is expanded, where the spectra were
vertically scaled to achieve equivalent absorbance intensities for
the amide-I carbonyl stretch;
[0062] FIG. 11 shows overlaid solid state FTIR spectra of isolated
water-soluble and water-insoluble fractions from digested soy,
where the N--H stretching region is expanded;
[0063] FIG. 12 shows overlaid solid state FTIR spectra of isolated
water-soluble polypeptide fractions from digested soy and digested
castor;
[0064] FIG. 13 shows overlaid solid state FTIR spectra of isolated
water-insoluble fractions from digested soy and soy flour;
[0065] FIG. 14 shows overlaid solid state FTIR surface ATR spectra
of the isolated water-insoluble/water-dispersible fractions from
multiple protein samples (digested soy lot 5-81, soy flour, castor
protein isolate lot 5-94, digested castor lot 5-90) where the
carbonyl amide region is expanded;
[0066] FIG. 15 is a two-dimensional HSQC .sup.1H--.sup.15N NMR
spectrum for digested castor (lot 5-83) in d6-DMSO, showing two
regions of interest denoted Region A and Region B;
[0067] FIG. 16 is a two-dimensional HSQC .sup.1H--.sup.15N NMR
spectrum for water-insoluble/water-dispersible polypeptide fraction
derived from digested castor (lot 5-83) in d6-DMSO, again showing
Region A and Region B;
[0068] FIG. 17 is a two-dimensional HSQC .sup.1H--.sup.15N NMR
spectrum, where Region A from FIG. 16 has been magnified;
[0069] FIG. 18 shows solid state FTIR spectra of isolated
water-soluble and water-insoluble fractions obtained from ground
soy meal, where the N--H and O--H stretch regions are expanded;
[0070] FIG. 19 shows overlaid solid state FTIR spectra of isolated
water-soluble and water-insoluble fractions obtained from ground
soy meal, where the carbonyl amide region is expanded and the
spectra were vertically scaled to achieve equivalent absorbance
intensities for the amide-I carbonyl stretch;
[0071] FIG. 20 is a graph showing the viscosity of a low-viscosity
adhesive composition containing ground canola meal as a function of
time, as described further in Example 5;
[0072] FIG. 21 is a graph showing the viscosity of a
higher-viscosity adhesive composition containing ground canola meal
as a function of time, as described further in Example 5.
[0073] FIG. 22 shows overlaid solid state FTIR spectra of isolated
water-soluble and water-insoluble/water-dispersible protein
fractions obtained from ground canola meal, where the N--H and O--H
stretch regions are expanded, as described further in Example
6.
[0074] FIG. 23 shows overlaid solid state FTIR spectra of isolated
water-soluble and water-insoluble/water-dispersible protein
fractions obtained from ground canola meal, where the carbonyl
amide region is expanded and the spectra were vertically scaled to
achieve equivalent absorbance intensities for the amide-I carbonyl
stretch, as described further in Example 6.
[0075] FIG. 24 shows overlaid solid state FTIR spectra of isolated
water-soluble and water-insoluble/water-dispersible protein
fractions obtained from soy flour, as described further in Example
6.
[0076] FIG. 25 shows overlaid solid state FTIR spectra of isolated
water-insoluble/water-dispersible protein fractions obtained from
soy meal and soy flour, as described further in Example 6.
[0077] FIG. 26 shows a container of macroscopically phase separated
mineral oil amalgam formed from a mixture of Nanomer I-44P
partially exfoliated in mineral oil that was dispersed in PMDI, as
further described in Example 7;
[0078] FIG. 27 shows a container holding a mixture of Nanomer I-44P
exfoliated in mineral oil and dispersed in PMDI that reacted to
form a "skin" on the surface of PMDI, as further described in
Example 7;
[0079] FIG. 28 shows a container holding an unusable solid mixture
formed by adding Nanomer-I44P (30% w/w) directly to PMDI, as
further described in Example 7; and
[0080] FIG. 29 shows a container holding Nanomer-PGV in PMDI,
illustrating that the Nanomer-PGV did not disperse in PMDI and
settles to the bottom of the container, as further described in
Example 7.
[0081] FIG. 30 is a graph showing how the weight of composite
materials changed over time when the composite material was placed
in water, as further described in Example 13. The graph also shows
the results of statistical modeling program (Design Ease 7.1.6 by
Stat-Ease, Inc., Minneapolis, Minn.) configured to predict the
change in weight of a composite placed in water, where the
composite has 13.34 weight percent binder (where the binder
contained 50 weight percent PMDI), 5 weight percent Nanomer I-44P,
and silicone/limonine, and the composite is formed by pressing at
200.degree. C. The sample labeled JM9 12 1-10 contained PMDI in
amount equal to 13.34 percent by weight of the composite.
[0082] FIG. 31 is a graph showing how the weight of composite
materials changed over time when the composite material was placed
in water, as further described in Example 13. The graph also shows
the results of statistical modeling program (Design Ease 7.1.6 by
Stat-Ease, Inc., Minneapolis, Minn.) configured to predict the
change in weight of a composite placed in water, where the
composite has 13.34 weight percent binder (where the binder
contained 37 weight percent PMDI), either 5 weight percent Nanomer
I-44P or no Nanomer I-44P, silicone/limonine, and the composite is
formed by pressing at 200.degree. C. The sample labeled JM9 12 1-10
contained PMDI in amount equal to 13.34 percent by weight of the
composite.
[0083] FIG. 32 is a graph illustrating the effect of
montmorillonite on moisture resistance of a composite (where the
composite was formed by pressing at 150.degree. C.), as further
described in Example 13. The composites tested contained 18.67
percent by weight binder. The binder contained 37.05 percent by
weight PMDI, and the oil carrier was a silicone/limonene mixture.
The diffusion rate of water was observed to decrease significantly
(p=0.0146) as the percentage of montmorillonite was increased.
[0084] FIG. 33 is a graph illustrating the effect of
montmorillonite on moisture resistance for composites (where the
composites where formed by pressing at 200.degree. C.), as further
described in Example 13. The composites tested contained 13.34
percent by weight binder, and the oil carrier was a
silicone/limonene mixture. In the absence of montmorillonite, the
diffusion rate of water was observed to decrease as the percentage
of PMDI was increased. However, in the presence of montmorillonite,
the diffusion rate remained constant, i.e., the diffusion rate was
independent of the PMDI concentration. Moreover, when PMDI was used
in combination with montmorillonite, the moisture resistance was
significantly improved at low amounts of PMDI (p=0.0083).
[0085] FIG. 34 depicts graphs showing the effect of montmorillonite
on moisture resistance (FIG. 34A) and apparent Tg (FIG. 34B) on
composites (where the composites were formed by pressing at
200.degree. C.), as further described in Example 13. The graphs
were generated from DOE modeling of the water diffusion coefficient
(D) and the apparent Tg as a function of I-44P concentration with
the following constraints: the composite contained 13.34 weight
percent binder; binder contained 41.5 weight percent PMDI; and oil
was a mixture of silicone and limonene. The apparent glass
transition temperature of the composite was observed to
significantly increase with increasing montmorillonite
concentration in the binder. The increase in Tg with increasing
levels of montmorillonite was accompanied by observations of
improved moisture resistance (i.e., decreased water diffusion
rate).
[0086] FIG. 35 is a graph illustrating the effect of
montmorillonite and PMDI on apparent Tg of the composites (where
the composites were formed by pressing at 200.degree. C.), as
further described in Example 13. The graph was generated from DOE
modeling of the apparent Tg as a function of increasing PMDI
concentration (in the presence and absence of montmorillonite). The
apparent glass transition temperature of the composite was observed
to increase with increasing PMDI concentration in the binder, but
only in the presence of the montmorillonite. The increase in Tg
with increasing levels of montmorillonite is consistent with
observations of improved moisture resistance (i.e., decreased water
diffusion rate).
[0087] FIG. 36 depicts an apparatus for burn testing wood composite
samples. FIG. 36A is a front view of the burn testing apparatus.
FIG. 36B is a side-angle view of the burn testing apparatus. FIG.
36C shows the Bernzomatic Butane Micro Torch in front of the burn
testing apparatus.
[0088] FIG. 37 depicts a particle board composite being burned with
a butane torch, as further described in Example 14.
[0089] FIG. 38 depicts the results of burn testing for multiple
particle board composites that had either (i) no Colmanite or (ii)
15 percent by weight Colmanite, as further described in Example
14.
DETAILED DESCRIPTION
[0090] The invention provides protein adhesive compositions and
methods of making and using such adhesives. Also, the invention
provides articles, such as wood composites, made using the protein
adhesive compositions. The protein adhesive compositions described
herein contain a reactive prepolymer, a protein component, and at
least one additive. The protein component is obtained from a
renewable feedstock and provides multiple advantages in the
preparation of adhesive compositions. For example, the protein
component facilitates preparation of adhesive compositions
containing an exfoliated clay or a partially exfoliated clay. In
particular, the protein component provides a solution to the
problem that exfoliated clays and partially exfoliated clays are
difficult to prepare in the presence of a polymer. Including the
protein component allows for easy preparation of exfoliated clays
and partially exfoliated clays in the presence of a polymer.
Further, the protein component stabilizes compositions containing
PMDI and an exfoliated clay or partially exfoliated clay. Other
advantages provided by the invention are described below.
[0091] The invention provides both single-pot, one-part adhesives
(a single mixture that, without the addition of other components,
functions as an adhesive) and two- or multi-part adhesives
(adhesives created by mixing together two or more parts, which when
mixed together function as an adhesive). FIG. 1 illustrates
multiple one-part and two-part adhesives that can be produced using
the protein component described herein (i.e., ground plant meal or
an isolated polypeptide composition described herein).
[0092] For example, a first type of one-part adhesive (denoted a
Type-1 adhesive) can be produced by mixing the protein component
(i.e., ground plant meal or an isolated polypeptide composition
described herein) with a diisocyanate-based prepolymer, a polymeric
isocyanate-based prepolymer, an epoxy-based prepolymer or a
combination thereof in the presence of an additive (for example, a
partially exfoliated clay). These one-part adhesives can further
comprise a polyol that is co-reacted with PMDI and the protein
component at the same time in one pot, or reacted in sequence by
sequential addition into a single pot. Such compositions can serve
as stand-alone one-part adhesives, or can be used as the Part-A
component in a two-part system.
[0093] A second type of one-part adhesive (denoted a Type-2
adhesive) can be produced by mixing the protein component with a
formulated polyurethane in the presence of an additive (e.g., a
partially exfoliated clay). A third type of one-part adhesive
(denoted a Type-3 adhesive) can be produced by mixing the protein
component with a latex polymer in the presence of an additive
(e.g., a partially exfoliated clay). A fourth type of one-part
adhesive (denoted a Type-4 adhesive) can be produced by mixing the
protein component with other additives.
[0094] Two-part adhesives, for example, as shown in FIG. 1, can be
prepared by mixing together two or more of the one-part adhesives.
The one-part adhesives used in these applications are stable on
their own but when mixed with second, different one-part adhesive,
the resulting mixture creates an adhesive composition. Exemplary
two-part adhesives, as shown in FIG. 1, can be created by combining
(i) the Type 1 and Type 3 adhesives to produce a fifth type of
adhesive (denoted Type-5 adhesive), (ii) the Type 2 and Type 4
adhesives to produce a sixth type of adhesive (denoted Type-6
adhesive); (iii) the Type 1 and Type 4 adhesives to produce a
seventh type of adhesive (denoted Type-7 adhesive), and (iv) the
Type 2 and Type 3 adhesives to produce an eight type of adhesive
(denoted Type-8 adhesive).
[0095] As will be discussed in more detail below, adhesives
described herein can be used in the production of a variety of
wood-based products including composite materials, laminates, and
laminates that contain composite materials. For example, the
adhesives can be used in the production of consolidated wood
composites, for example, chipboard (also known as OSB), fiberboard,
and related composite wood products, as well as in the production
of engineered lumber composites, for example, I-beams (I-joists),
laminated veneer lumber (LVL), and other types of structural lumber
composites.
[0096] By way of example, the adhesives described herein have a
number of important advantages in the production of wood-based
(lignocellulosic) composites relative to other commonly used wood
adhesives. The advantages include higher moisture tolerance and the
lack of formaldehyde emissions.
[0097] The following sections describe the isolation and
characterization of protein component useful in making emulsions,
reactive prepolymers, additives, general considerations for
adhesive compositions, methods for making emulsions, dispersions
and adhesives, as well as certain applications and uses of the
emulsions, dispersions and adhesives described herein.
I. Ground Plant Meal
[0098] Plant meal can be obtained from commercial sources or
derived from corn, wheat, sunflower, cotton, rapeseed, canola,
castor, soy, camelina, flax, jatropha, mallow, peanuts, algae,
sugarcane bagasse, tobacco, whey, or a combination thereof. Plant
meal can be ground using techniques known in the art, such as
hammer mill (cryogenic or ambient) or ball mill. In certain
embodiments, the plant meal is ground and screened to isolate plant
meal particles having a particle size in the range of from about 1
.mu.m to about 400 .mu.m, from about 1 .mu.m to about 350 .mu.m,
from about 1 .mu.m to about 300 .mu.m, from about 1 .mu.m to about
250 .mu.m, from about 1 .mu.m to about 200 .mu.m, from about 1
.mu.m to about 100 .mu.m, from about 1 .mu.m to about 50 .mu.m,
from about 5 .mu.m to about 250 .mu.m, from about 5 .mu.m to about
200 .mu.m, from about 5 .mu.m to about 150 .mu.m, from about 5
.mu.m to about 100 .mu.m, from about 5 .mu.m to about 50 .mu.m,
from about 10 .mu.m to about 250 .mu.m, from about 10 .mu.m to
about 100 .mu.m, from about 10 .mu.m to about 90 .mu.m, from about
10 .mu.m to about 70 .mu.m, from about 10 .mu.m to about 50 .mu.m,
from about 20 .mu.m to about 150 .mu.m, from about 20 .mu.m to
about 100 .mu.m, from about 20 .mu.m to about 80 .mu.m, from about
20 .mu.m to about 70 .mu.m, from about 20 .mu.m to about 60 .mu.m,
from about 25 .mu.m to about 150 .mu.m, from about 25 .mu.m to
about 100 .mu.m, from about 25 .mu.m to about 50 .mu.m, from about
50 .mu.m to about 150 .mu.m, or from about 50 .mu.m to about 100
.mu.m.
[0099] Preferred types of ground plant meal are characterized by
their ability to suspend or emulsify oil in water or water in oil
to produce a homogeneous suspension or emulsion stable, by visual
inspection, for least 5 minutes. In certain embodiments, the
dispersion or emulsion exhibits substantially no phase separation
by visual inspection for at least 10, 15, 20, 25, or 30 minutes, or
even 1, 2, 3, 4, 5, 6, 9, 12, 18, or 24 hours after mixing the
ground plant meal with the oil. One assay that can be used to
identify such preferred ground plant meals involves mixing 26 parts
(by weight) of a ground plant meal sample with 74 parts (by weight)
of water. The resulting solution or dispersion is mixed with 26
parts (by weight) of oil, for example, PMDI. Under these
conditions, the ground plant meal produces a dispersion or emulsion
that exhibits substantially no phase separation by visual
inspection for at least 5 minutes after mixing the ground plant
meal with the oil. This assay can be performed with oils other than
PMDI, such as mineral oil, soybean oil, derivatized soybean oil,
motor oil, castor oil, derivatized castor oil, dibutyl phthalate,
epoxidized soybean oil, corn oil, vegetable oil, caprylic
triglyceride, Eucalyptus oil, tributyl o-acetylcitrate, or an
organic polyisocyanate other than PMDI.
[0100] An additive may be added to the plant meal prior to grinding
to aid in the grinding process or produce a ground plant meal with
superior physical properties for use in manufacturing an adhesive
composition, e.g., providing a ground plant meal with improved flow
properties, superior packing density, reduced tendency to cake,
reduced tendency to bridge, superior particle dispersibility in
aqueous mixtures, modulation of particle coupling and/or wetting
characteristics with other materials in the adhesive composition,
and the like. Alternatively, the additive may be added to the plant
meal during the grinding process used to produce ground plant
meal.
[0101] Additives that impart superior performance properties to the
adhesive composition or the wood composite formed from the adhesive
composition may be added to the plant meal before or during
grinding or may be added to the ground plant meal produced from the
grinding process. Exemplary additives includes those described in
Sections IV and V below, and, in particular, include agents that
improve moisture resistance of the wood composite, formaldehyde
scavenging agents, and composite-release promoting agents. The
additive may be in solid or liquid form, and the additive may be
characterized according to whether it reacts with materials in the
adhesive composition or does not react with materials in the
adhesive composition.
[0102] Exemplary solid additives include (i) inorganic additives
such as silica, pigments, catalysts, clays (including intercalated
clays, exfoliated clays, and partially exfoliated clays), and the
like, and (ii) organic compounds such as fatty acids (e.g., stearic
acid, lauric acid) lignin, tannins, amine-containing compounds,
urea, hydrocarbon waxes/liquids, and fluorocarbon waxes/liquids.
Solid additives may be used in amounts ranging, for example, from
about 0.001% w/w to 40% w/w of the ground plant meal mixture, from
about 0.1% w/w to about 20% w/w of the ground plant meal mixture,
or from about 0.5% w/w to about 15% w/w of the ground plant meal
mixture.
[0103] Liquid additives may be dry blended with ground plant meal.
The amount of liquid additive should be less than that which causes
the ground plant meal to cake or bridge during a manufacturing
process. Accordingly, in certain embodiments, the amount of liquid
additive(s) is less than about 10% by weight of the ground plant
meal mixture containing the additive(s). In certain other
embodiments, the amount of liquid additive(s) is less than about 5%
by weight, or even less than about 2% by weight, of the ground
plant meal mixture containing the additive. The liquid additive may
be characterized as reactive or non-reactive. Reactive liquid
additives may include organosilanes, low molecular weight alcohols
such as glycerin or propylene glycol, liquid polyol oligomers,
liquid polyurethane oligomers, addition-polymerizable monomers,
condensation-polymerizable monomers, and reactive oils such as
epoxidized soy oil or castor oil. Other liquid additives include
amalgams of a carrier oil and a partially exfoliated clay as
described herein.
[0104] Accordingly, one aspect of the invention provides a ground
plant meal mixture comprising ground plant meal and one or more
additives described herein, and use of such a mixture in an
adhesive composition to form a wood composite.
II. Isolated Polypeptide Composition
[0105] The isolated polypeptide composition can be derived from
renewable plant biomass, such as corn, wheat, sunflower, cotton,
rapeseed, canola, castor, soy, camelina, flax, jatropha, mallow,
peanuts, algae, sugarcane bagasse, tobacco, whey, or a combination
thereof, using procedures described herein. The isolated
polypeptide composition contains water-insoluble/water-dispersible
protein fraction, optionally in combination with a water-soluble
protein fraction. It is understood that the
water-insoluble/water-dispersible protein fraction can disperse
conventional oils (for example, reactive oils, or an organic
polyisocyanate, which is a reactive prepolymer) that are used to
make water and moisture resistant adhesives. Thus, in embodiments
where the isolated polypeptide composition contains a mixture of i)
water-insoluble/water-dispersible protein fraction and ii)
water-soluble protein fraction, the ratio of i)
water-insoluble/water-dispersible protein fraction to ii)
water-soluble protein fraction is such that the isolated
polypeptide composition is able to disperse the prepolymer in an
aqueous medium. Moreover, when the adhesive composition contains an
isolated polypeptide composition as the sole protein source, then,
in certain embodiments, the adhesive composition comprises at least
1% (w/w) urea. The adhesive composition optionally further
comprises an additive such as polymer latex to form moisture
resistant adhesives (such as to adhere a paper label to a glass
bottle or jar).
[0106] The terms "protein" and "polypeptide" are used synonymously
and refer to polymers containing amino acids that are joined
together, for example, via peptide bonds or other bonds, and may
contain naturally occurring amino acids or modified amino acids.
The polypeptides can be isolated from natural sources or
synthesized using standard chemistries. The polypeptides may be
modified or derivatized by either natural processes, such as
post-translational processing, or by chemical modification
techniques well known in the art. Modifications or derivatizations
may occur anywhere in the polypeptide, including, for example, the
peptide backbone, the amino acid side-chains and the amino or
carboxyl termini. Modifications include, for example, cyclization,
disulfide bond formation, demethylation, deamination, formation of
covalent cross-links, formation of pyroglutamate, formylation,
gamma-carboxylation, glycosylation, GPI anchor formation,
hydroxylation, iodination, methylation, myristolyation, oxidation,
pegylation, proteolytic digestion, phosphorylation, etc. As used
throughout, the term "isolated" refers to material that is removed
from its original environment (e.g., the natural environment if it
is naturally occurring).
A. Preparation of Isolated Polypeptide Composition
[0107] The starting material for producing an isolated polypeptide
composition can be derived from one or more of corn, wheat,
sunflower, cotton, rapeseed, canola, castor, soy, camelina, flax,
jatropha, mallow, peanuts, algae, sugarcane bagasse, tobacco, or
whey. For example, the starting material for producing an isolated
polypeptide composition can be plant meal or a protein isolate.
Depending on the properties desired for the adhesive, the isolated
polypeptide composition may contain a mixture of i)
water-insoluble/water-dispersible protein fraction and ii)
water-soluble protein fraction. The
water-insoluble/water-dispersible protein fraction and the
water-soluble protein fraction can be obtained from plant material
using a Water Washing Method or an Acid Precipitation Method, such
as those described in more detail below. In certain instances, the
composition obtained from the Water Washing Method and or Acid
Precipitation Method may be further modified by enzymatic digestion
and/or chemical modification.
Water Washing Method
[0108] Water-insoluble/water-dispersible protein fraction can be
isolated from plant meal (e.g., castor meal, soy meal, or canola
meal) by washing with water to remove water-soluble proteins and
water-soluble components. The residue left after the water wash is
the water-insoluble/water-dispersible protein fraction. A
water-soluble protein fraction can be isolated by concentrating
aqueous extracts from the water washing. Plant meal used in the
process can be ground to reduce particle size, which may, in
certain instances, provide processing advantages.
[0109] Water-insoluble/water-dispersible protein fraction can also
be isolated from, for example, soy protein isolate or from soy
flour. The procedure involves washing the soy protein isolate or
soy flour with water to remove water-soluble proteins and
water-soluble components from the respective soy protein isolate or
the water-flour mixture.
[0110] The water-insoluble/water-dispersible protein fraction
described above may be used directly as a wet slurry in an adhesive
composition, or it may be dried and optionally ground to form a
particulate mixture.
[0111] In certain embodiments, the pH of the water used to wash the
plant meal is about 7. In certain other embodiments, the pH of the
water used to perform one or more of the washes may be alkaline.
Conditions (e.g., number of water washes) for the Water Washing
Method may be adjusted in order to maximize the performance
properties of the water-insoluble/water-dispersible protein
fraction, such as its ability to disperse an oil in water or water
in oil.
[0112] The Water Washing Method is a simple and economical
procedure for obtaining water-insoluble/water-dispersible protein
fraction. Due to the simplicity of the method, it is contemplated
that the Water Washing Method can be used to provide large
quantities of water-insoluble/water-dispersible protein fraction
for manufacture of adhesive compositions.
[0113] It is appreciated that the water-insoluble/water-dispersible
protein fraction obtained using the Water Washing Method may, in
certain instances, contain water-insoluble components in addition
to water-insoluble protein. If the performance requirements of an
adhesive require a water-insoluble/water-dispersible protein
fraction having a larger amount of water-insoluble protein, then
the Acid Precipitation Method can be used to prepare the
water-insoluble/water-dispersible protein fraction.
Acid Precipitation Method
[0114] Water-insoluble/water-dispersible protein fraction
comprising a relatively higher quantity of water-insoluble protein
can be prepared using the Acid Precipitation Method. The Acid
Precipitation Method is shown schematically in FIG. 2. This method
can also be used to obtain water-soluble protein fraction.
[0115] As shown in FIG. 2, the starting material (for example,
ground meal) is dispersed in alkaline, aqueous media at pH 6.5-13
for at least 5 minutes, at least 20 minutes, at least 40 minutes or
at least 1 hour, to form a mixture. Starting materials include, for
example, canola meal, canola protein isolate, castor meal, castor
protein isolate, soy meal, or soy protein isolate, or a combination
thereof. Then, the pH of the mixture is lowered by the addition of
acid (to provide a mixture with a pH in the range of, for example,
4.0-5.0) to precipitate both a portion of water-soluble proteins
and water-insoluble proteins. Then, the water-insoluble material
(i.e., the precipitate) is harvested. The harvested material is
washed with water and the remaining
water-insoluble/water-dispersible material is harvested. The
resulting water-insoluble/water-dispersible material can be used as
is or dried using drying techniques known in the art.
[0116] Further, as shown in FIG. 2, the water-soluble proteins can
be harvested at a number of places. For example, water-soluble
proteins can be harvested after the starting material is mixed in
aqueous media, after neutralization, and as a supernatant from the
washing steps. The resulting protein can be used as is or dried
using drying techniques known in the art.
[0117] The water-insoluble/water-dispersible material produced
according to the method in FIG. 2 can disperse or emulsify oil in
water or water in oil. The physical and chemical properties of the
water-soluble/water-dispersible fraction are described in more
detail below. In addition, the physical and chemical properties of
the water-soluble protein fraction are described in more detail
below.
Enzymatic Digestion/Chemical Hydrolysis
[0118] The Water Washing Method and Acid Precipitation Method can
include one or more enzyme digestion and/or chemical hydrolysis
steps. Digestion can be facilitated using one or more enzymes, and
hydrolysis can be facilitated using one or more chemicals, for
example, acid- or alkali-based hydrolysis. For example, in the Acid
Precipitation Method, the starting material (for example, the
ground meal) can be exposed to enzymatic digestion before or after,
or both before and after the incubation of the starting material in
the alkaline aqueous media. Alternatively, or in addition, an
enzymatic digestion step can be performed on the material following
addition of acid to provide a mixture with a pH in the range of 4.0
to 5.0. Alternatively, or in addition, the harvested
water-insoluble/water-dispersible material can be exposed to
enzymatic digestion prior to washing. Alternatively, or in
addition, the material harvested after washing can be exposed to
enzymatic digestion. Chemical hydrolysis, however, can occur with
or replace the enzymatic digestion steps noted above.
[0119] Under certain circumstances residual basic species and
alkali metals present in chemically digested proteins are not
compatible with polyisocyanates and can cause trimerization of the
isocyanate groups, leading to stability problems in the final
polyisocyanate compositions. Enzymatic digestion, however, can be
used to avoid or reduce isocyanate stability problems associated
with some chemical hydrolysis steps.
[0120] It is understood that enzymes useful in the digestion of the
protein fractions include endo- or exo-protease of bacterial,
fungal, animal or vegetable origin or a mixture of thereof. Useful
enzymes include, for example, a serine-, leucine-, lysine-, or
arginine-specific protease. Exemplary enzymes include trypsin,
chymotrypsins A, B and C, pepsin, rennin, microbial alkaline
proteases, papain, ficin, bromelain, cathepsin B, collagenase,
microbial neutral proteases, carboxypeptidases A, B and C,
camosinase, anserinase, V8 protease from Staphylococcus aureus and
many more known in the art. Also combinations of these proteases
may be used.
[0121] Also commercially available enzyme preparations such as, for
example, Alcalase.RTM., Chymotrypsine 800s, Savinase.RTM.,
Kannase.RTM., Everlase.RTM., Neutrase.RTM., Flavourzyme.RTM. (all
available from Novo Nordisk, Denmark), Protex 6.0L, Peptidase FP,
Purafect.RTM., Purastar OxAm.RTM., Properase.RTM. (available from
Genencor, USA), Corolase L10 (Rohm, Germany), Pepsin (Merck,
Germany), papain, pancreatin, proleather N and Protease N (Amano,
Japan), BLAP and BLAP variants available from Henkel, K-16-like
proteases available from KAO, or combinations thereof. Table 1
describes the amino acid specificity of certain useful
endonucleases.
TABLE-US-00001 TABLE 1 Nota- No Amino Acid tion Commercial
Endopeptidase(s) 1 Alanine A Pronase .RTM.; Neutrase .RTM.: 2
Cysteine C Papain 3 Aspartic D Fromase .RTM.; 4 Glutamic E Alcalase
.RTM.; 5 Phenylalanine F Neutrase .RTM.: Fromase .RTM. 6 Glycine G
Flavorzyme .RTM.; Neutrase .RTM.: 7 Histidine H Properase .RTM.; 8
Isoleucine I Neutrase .RTM.: 9 Lysine K Alcalase .RTM.; Trypsin;
Properase .RTM. 10 Leucine L Alcalase .RTM.; Esperase .RTM.;
Neutrase .RTM.: 11 Methionine M Alcalase .RTM.; Neutrase .RTM.: 12
Asparigine N Savinase .RTM.; Flavourzyme .RTM.; Duralase .RTM.; 13
Proline P Pronase .RTM.; Neutrase .RTM.: 14 Glutamine Q Alcalase
.RTM. 15 Arginine R Trypsin; Properase .RTM.; 16 Serine S Savinase
.RTM.; Flavourzyme .RTM.; Duralase .RTM.; 17 Threonine T Savinase
.RTM.; Flavourzyme .RTM.; Duralase .RTM.; 18 Valine V Neutrase
.RTM.: 19 Tryptophane W Neutrase .RTM.: Fromase .RTM. 20 Tyrosine Y
Alcalase .RTM.; Esperase .RTM.; Fromase .RTM.
[0122] Depending upon the choice enzyme(s), enzymatic digestion
usually is conducted under aqueous conditions at the appropriate pH
conditions (for example, depending upon the enzyme or enzyme
mixture at neutral or at low pH). In certain digestion systems, the
digestion optimally occurs at a pH less than 9, or less than 8. For
certain applications the pH of the aqueous protein digestion system
is in the range of 3-9, 4-8 or 5-7.5.
[0123] Once digestion has proceeded to the desired extent, the
resulting product optionally is washed and used as is or dried to
form a powder. The drying can be performed by techniques known in
the art, including spray drying, freeze drying, oven drying, vacuum
drying, or exposure to desiccating salts (such as phosphorous
pentoxide or lithium chloride).
Chemical Modification of Proteins
[0124] In certain embodiments, the proteins in the isolated protein
fractions are further derivatized. Suitable processes for
derivatization of the polypeptide fractions are provided in the
literature. The nature and extent of modification will depend in
large part on the composition of the starting material. The
derivative can be produced by, for example, replacing at least a
portion of primary amine groups of said isolated protein with
hydroxyl groups, deaminating the protein, or replacing a portion of
amide groups of the protein with carboxyl groups, etc. In other
embodiments, the isolated polypeptide compositions described herein
are obtained by reacting the protein with protein modifying agents,
for example, nitrous oxide, nitrous acid, salts of nitrous acid, or
a combination thereof
B. Characterization of the Water-Insoluble/Water-Dispersible
Protein Fraction
[0125] The water-insoluble/water-dispersible protein fraction can
be characterized accordingly to multiple physical properties. For
example, the water-insoluble/water-dispersible protein fraction can
be characterized according to its capacity to disperse oil in water
or water in oil (see Example 4). The
water-insoluble/water-dispersible protein fraction should, at a
minimum, disperse at least some oil in water or water in oil. The
amount of oil that can be dispersed in water or the amount of water
that can be dispersed in oil is a physical property that
characterizes a water-insoluble/water-dispersible protein
fraction.
[0126] The water-insoluble/water-dispersible protein fraction can
also be characterized according to i) absortion band(s) observed by
solid state FTIR, ii) molecular weight range of the proteins in the
fraction, and iii) features in a solution state, two-dimensional
proton-nitrogen coupled NMR spectrum of the fraction.
[0127] Accordingly, in certain embodiments, the
water-insoluble/water-dispersible fraction is characterized by one
or more of the following features: (i) a prominent amide-I
absorption band between about 1620 cm.sup.-1 and 1645 cm.sup.-1,
(ii) an amide-II band between approximately 1514 cm.sup.-1 and 1545
cm.sup.-1, as determined by solid state FTIR, and (iii) is capable
of dispersing an oil-in-water or water-in-oil to produce a
homogeneous emulsion that is stable for least 5 minutes.
[0128] In certain other embodiments, the
water-insoluble/water-dispersible fraction is characterized by one
or more of the following features: (i) an amide-I absorption band
between about 1620 cm.sup.-1 and 1642 cm.sup.-1 and an amide-II
band between approximately 1514 cm.sup.-1 and 1540 cm.sup.-1, as
determined by solid state FTIR, (ii) a prominent 2.degree. amide
N--H stretch absorption band centered at about 3272 cm.sup.-1, as
determined by solid state FTIR, and (iii) is capable of dispersing
an oil-in-water or water-in-oil to produce a homogeneous emulsion
that is stable for least 5 minutes.
[0129] In certain other embodiments, the
water-insoluble/water-dispersible fraction is characterized by one
or more of the following features: (i) an amide-I absorption band
between about 1620 cm.sup.-1 and 1632 cm.sup.-1 and an amide-II
band between approximately 1514 cm.sup.-1 and 1521 cm.sup.-1, as
determined by solid state FTIR, (ii) a prominent 2.degree. amide
N--H stretch absorption band centered at about 3272 cm.sup.-1, as
determined by solid state FTIR, (iii) an average molecular weight
of between about 600 and about 2,500 Daltons (determined using, for
example, MALDI mass spectrometry), (iv) two protonated nitrogen
clusters defined by .sup.15N chemical shift boundaries at about
86.2 ppm and about 87.3 ppm, and .sup.1H chemical shift boundaries
at about 7.14 ppm and 7.29 ppm for the first cluster, and .sup.1H
chemical shift boundaries at about 6.66 ppm and 6.81 ppm for the
second cluster, as determined by solution state, two-dimensional
proton-nitrogen coupled NMR.
[0130] As described above, water-insoluble/water-dispersible
fraction is capable of suspending or emulsifying oil in water or
water in oil to produce a homogeneous suspension or emulsion
stable, by visual inspection, for least 5 minutes. In certain
embodiments, the dispersion or emulsion exhibits substantially no
phase separation by visual inspection for at least 10, 15, 20, 25,
or 30 minutes, or even 1, 2, 3, 4, 5, 6, 9, 12, 18, 24 hours after
mixing the polypeptide composition with the oil. As shown in
Example 4, the water-insoluble/water-dispersible fraction is
capable of emulsifying or dispersing a wide selection of oils,
including, for example, an organic polyisocyanate (for example,
PMDI) mineral oil, soybean oil, derivatized soybean oil, motor oil,
castor oil, derivatized castor oil, dibutyl phthalate, epoxidized
soybean oil, corn oil, vegetable oil, caprylic triglyceride,
Eucalyptus oil, and tributyl o-acetylcitrate. In an exemplary
assay, 14 parts (by weight) of a protein sample of interest is
mixed with 86 parts (by weight) of water and the resulting solution
or dispersion is mixed with 14 parts (by weight) of oil, for
example, PMDI. Under these conditions, the
water-insoluble/water-dispersible protein fraction produces a
dispersion or emulsion that exhibits substantially no phase
separation by visual inspection for at least 5 minutes after mixing
the polypeptide composition with the oil. The assay can be
performed with the other oils. Another assay that can be used
involves mixing 26 parts (by weight) of a protein sample with 74
parts (by weight) of water. The resulting solution or dispersion is
mixed with 26 parts (by weight) of oil, for example, PMDI. Under
these conditions, the water-insoluble/water-dispersible protein
fraction produces a dispersion or emulsion that exhibits
substantially no phase separation by visual inspection for at least
5 minutes after mixing the polypeptide composition with the oil.
This assay using 26 parts (by weight) of a protein can be performed
with oils other than PMDI, such as the oils described above in
connection with the assay using 14 parts (by weight) of protein
sample.
[0131] In certain other embodiments, the
water-insoluble/water-dispersible fraction is further characterized
by its ability to emulsify or disperse, in water, one or more of
the following hydrophobic liquids and hydrophobic solids: a
silicone (e.g., a silicone oil or a silicone gel), a fluorocarbon
(e.g., a solid wax fluorocarbon or a liquid oil fluorocarbon), a
fluorinated polyol, a wax (e.g., a solid carboxylic acid ester
(e.g., an ester of stearic acid), a salt of a carboxylic acid
(e.g., a salt of stearic acid, e.g., zinc stearate), a hydrocarbon
wax, and a fluorinated hydrocarbon wax), a liquid carboxylic acid
ester that is hydrophobic, and a liquid hydrocarbon.
[0132] In yet other embodiments, the
water-insoluble/water-dispersible fraction is further characterized
by its ability to emulsify or disperse one or more of the following
agents in water: BE Square 165 Amber Petroleum Microcrystalline Wax
from Baker Hughes, Inc.; limonene; FluoroLink D-10 Fluorinated
polyol from Solvay Solexis, Inc; Tego Protect-5000 functionalized
silicone fluid from Evonik Tego Chemie GmbH; Soy Lecithin; Castor
Oil; Zinc Stearate; Dow Corning FS-1265 Fluid, 300 cST
(Trifluoropropyl Methicone) from Dow Corning; and T-Sil-80, hydroxy
terminated polydimethylsiloxane from Siovation, Inc.
[0133] In yet other embodiments, the
water-insoluble/water-dispersible fraction is further characterized
by its ability to emulsify or disperse an amalgam comprising a
partially exfoliated clay in an oil carrier. In yet other
embodiments, the water-insoluble/water-dispersible fraction is
further characterized by its ability to emulsify or disperse a
melted wax in water. In certain embodiments, the dispersion or
emulsion exhibits substantially no phase separation by visual
inspection for at least 10, 15, 20, 25, or 30 minutes, or even 1,
2, 3, 4, 5, 6, 9, 12, 18, 24 hours after mixing the polypeptide
composition with the agent.
[0134] In certain embodiments, the
water-insoluble/water-dispersible fraction is substantially free of
primary amines, carboxylic acids, amine salts, and carboxylate
salts.
[0135] The water-insoluble/water-dispersible protein fraction can
act as a surfactant to an organic polyisocyanate (e.g., PMDI),
lowering interfacial tension to the point where the water insoluble
organic polyisocyante is readily emulsified with minimal energy
input, creating an oil-in-water or water-in-oil emulsion. When the
source material is a whole meal or a protein isolate derived from
soy, castor or canola, a stable emulsion can be obtained using
undigested substantially insoluble (fractionated) protein. In
certain embodiments, a stable emulsion of polyisocyanate (e.g.,
PMDI) in water can be achieved when the isolated fractionated
polypeptide is comprised of a water-insoluble/water-dispersible
fraction, either alone, or in combination with a water soluble
component. The acceptable level of the water-soluble component will
depend in large part upon the adhesive performance characteristics
that are needed for the end-use application. The best overall
combination of adhesive performance properties (in terms of PMDI
emulsification, bond strength, and water resistance) is achieved
when the level of the water-soluble fraction is minimized, and when
the level of the water-insoluble dispersible fraction is maximized.
For example, where high bond strengths and high degrees of moisture
resistance are simultaneously desired from an adhesive formulation
as provided herein, the water-insoluble/water-dispersible fraction
comprises between about 50%-100%, 50%-80%, 60%-100%, or 60%-90%
(w/w) of the entire isolated polypeptide composition that is
incorporated into the adhesive formulation.
[0136] In applications where achieving high bond strengths and oil
(e.g., PMDI) dispersibility in water are more important than
maximizing moisture resistance, the
water-insoluble/water-dispersible fraction optionally comprises no
less than about 45% of the isolated polypeptide composition that is
incorporated into the adhesive formulation. Under certain
circumstances, for example, an adhesive prepared with digested
castor protein extracted from castor meal, the process of isolating
and digesting a protein can lead to a polypeptide composition that
implicitly contains both water-soluble and water-insoluble
fractions at ratios sufficient to simultaneously disperse oil in
water while yielding high bond strength adhesives. The process of
digesting a whole meal can lead to a mixture that includes a
polypeptide composition that implicitly contains both water-soluble
and water-insoluble fractions at ratios sufficient to
simultaneously disperse oil in water while yielding high bond
strength adhesives (an example includes adhesives prepared with
digested whole castor meal). Where the process of digestion or
extraction does not lead to a polypeptide composition that
implicitly comprises both water-soluble and water-insoluble
fractions at ratios which are sufficient to simultaneously disperse
oil in water while yielding high bond strength adhesives, an
additional fractionation step can be used to isolate sufficient
levels of the water-insoluble/water-dispersible fraction from the
polypeptide composition, so that the ratio of the water-insoluble
fraction to the water-soluble fraction can be adjusted in the
formulated adhesive for the purpose of achieving the desired
combination of end-use properties. In certain embodiments, it may
be desirable to obtain an isolated polypeptide composition
containing very little or no water-soluble protein fraction, such
as through water washing of plant meal, optimization of the Acid
Precipitation Method, or enzymatic digestion to reduce the amount
of water-soluble protein.
[0137] The isolated polypeptide composition obtained using the
Water Washing Method may contain a mixture of i)
water-insoluble/water-dispersible protein fraction and ii)
water-soluble protein fraction. Depending on the composition of the
protein source material (e.g., soy meal, castor meal, or canola
meal), the isolated polypeptide composition obtained using the
Water Washing Method may contain a sufficient amount of
water-insoluble/water-dispersible protein fraction to disperse oil
or water. If, however, the isolated polypeptide composition
obtained using the Water Washing Method contains insufficient
water-insoluble/water-dispersible protein fraction, then higher
purity water-insoluble/water-dispersible protein fraction obtained
from the Acid Precipitation Method can be added to the isolated
polypeptide composition in order to increase the relative amount of
water-insoluble/water-dispersible protein fraction.
[0138] In certain embodiments, the polypeptide fractions used in
the compositions and methods provided herein, can have a weight
average molecular weight of between about 500 and 25,000 Daltons.
Useful polypeptide fractions can have a weight average molecular
weight of between about 500 and 2,500 Daltons, between about 700
and 2,300 Da., between about 900 and 2,100 Da., between about 1,100
and 1,900 Da., between about 1,300 and 1,700 Da., or between about
1,000 and 1,300 Da., between about 2,000 and 2,500 Da., or between
about 1,000 and 2,500 Da.
[0139] The isolated polypeptide composition can be used to make
adhesive compositions, as described herein, by combining them with
a reactive prepolymer. Reactive prepolymers can be selected from
the group consisting of an organic polyisocyanate; a reaction
product between an organic polyisocyanate and a polypeptide, a
polyol, an amine based polyol, an amine containing compound, a
hydroxy containing compound, or a combination thereof; an epoxy
containing compound; a reaction product between an epoxy containing
compound and a polypeptide, a polyol, an amine based polyol, an
amine containing compound, a hydroxy containing compound, or a
combination thereof; an organosilane; a polymer latex; a
polyurethane; and a mixture thereof.
[0140] When making the adhesives, the isolated polypeptide
composition, in certain embodiments, is capable of dispersing the
reactive prepolymer in the aqueous medium to produce a stable
dispersion or a stable emulsion. The dispersion or emulsion
exhibits substantially no phase separation by visual inspection for
at least 5 minutes after mixing the isolated polypeptide
composition with the reactive prepolymer. In certain embodiments,
the dispersion or emulsion exhibits substantially no phase
separation by visual inspection for at least 10, 15, 20, 25, or 30
minutes, or even 1, 2, 3, 4, 5, 6, 9, 12, 18, 24 hours after mixing
the isolated polypeptide composition with the reactive
prepolymer.
[0141] In certain embodiments, the
water-insoluble/water-dispersible protein fraction provides a
stable emulsion, dispersion or suspension, for example, an aqueous
emulsion, dispersion or suspension, comprising from about 1% to
about 90% (w/w) of an oil and from about 1% to about 99% (w/w) of
an isolated polypeptide composition, wherein the isolated
polypeptide composition produces a stable emulsion or dispersion of
the oil in an aqueous medium. The aqueous emulsion, dispersion or
suspension optionally comprises from about 1% to about 50% (w/w) of
oil and from about 1% to about 99% (w/w) of the isolated
polypeptide composition. The term "stable" when used in reference
to the emulsions, suspensions and dispersions refers to the ability
of the polypeptide fraction described herein to create a
kinetically stable emulsion for the duration of the intended
application of the dispersion or emulsion. The terms "emulsion,"
"dispersion," and "suspension" are used interchangeably herein.
[0142] In certain embodiments, the polypeptide composition has a
polydispersity index (PDI) of between about 1 and 1.15. In certain
embodiments, the PDI of the adhesives provided created using the
polypeptides described herein is between about 1 and about 3,
between 1 and 1.5, between 1.5 and 2, between 2 and 2.5, between
2.5 and 3, between 1 and 2, between 1.5 and 2.5, or between 2 and
3.
C. Characterization of Water-Soluble Protein Fraction
[0143] The water-soluble protein fractions, for example, the
water-soluble protein fractions isolated pursuant to the protocol
set forth in FIG. 2, are substantially or completely soluble in
water.
[0144] The water-soluble protein fractions have one or more of the
following six features. (i) An amide-I absorption band between
about 1633 cm.sup.-1 and 1680 cm.sup.-1, as determined by solid
state FTIR. (ii) An amide-II band between approximately 1522
cm.sup.-1 and 1580 cm.sup.-1, as determined by solid state FTIR.
(iii) Two prominent 1.degree. amide N--H stretch absorption bands
in the range of from about 3100-3200 cm.sup.-1, and in the range of
from about 3300-3400 cm.sup.-1, as determined by solid state FTIR.
(iv) A prominent cluster of protonated nitrogen nuclei defined by
.sup.15N chemical shift boundaries at about 94 ppm and about 100
ppm, and .sup.1H chemical shift boundaries at about 7.6 ppm and 8.1
ppm, as determined by solution state, two-dimensional
proton-nitrogen coupled NMR. (v) An average molecular weight of
between about 600 and about 2,500 Daltons, for example, as
determined by MALDI. (vi) An inability to stabilize an oil-in-water
or water-in-oil dispersion or emulsion, where the water and oil
components of the mixture form an unstable suspension that
macroscopically phase separates under static conditions within five
minutes after mixing. This can be tested by dissolving or
dispersing 14 parts (by weight) of a protein sample of interest in
86 parts (by weight) of water and then mixing the resulting
solution with 14 parts (by weight) of oil, for example, PMDI. Under
these conditions, a water-soluble protein is characterized by an
inability to stabilize an oil-in-water emulsion, where the oil and
water components form an unstable suspension that macroscopically
phase separates under static conditions within five minutes after
mixing. Another procedure for evaluating the inability of a protein
sample to stabilize an oil-in-water or water-in-oil dispersion or
emulsion is to mix 26 parts by weight of a water-soluble
protein-containing fraction isolated from whole ground meal in 74
parts (by weight) of water, and then mix the resulting solution
with 26 parts (by weight) of oil, for example, PMDI. Under these
conditions, a water-soluble protein-containing fraction is
characterized by an inability to stabilize an oil-in-water
emulsion, where the oil and water components form an unstable
suspension that macroscopically phase separates under static
conditions within five minutes after mixing.
III. Reactive Prepolymer
[0145] When making suitable emulsions, dispersions, and adhesives,
the protein component (i.e., ground plant meal or isolated protein
composition) described hereinabove can be combined with a reactive
prepolymer. The term "prepolymer" is understood to mean a compound,
material or mixture that is capable of reacting with a protein
component described herein to form an adhesive polymer. Exemplary
prepolymers include, for example, isocyanate-based prepolymers,
epoxy-based prepolymers, and latex prepolymers. Further, for
illustration, the term "prepolymer" includes full prepolymers and
partial prepolymers (referred to as semiprepolymers,
pseudoprepolymers, or quasiprepolymers in certain embodiments). One
example of a quasi prepolymer is a NCO-terminated product prepared
from a diisocyanate and polyol in which the prepolymer is a mixture
of (i) a product prepared from the diisocyanate and polyol, and
(ii) unreacted diisocyanate. On the other hand, an example of a
full prepolymer is the product formed by reacting an isocyanate
with a particular polyol blend so that there are substantially no
residual monomeric isocyanates in the finished product.
[0146] An isocyanate-based prepolymer can be an organic
polyisocyanate, which can be (i) a polyisocyanate (or monomeric
diisocyanate) that has not been reacted with another compound, (ii)
a polyisocyanate modified by various known self-condensation
reactions of polyisocyanates, such as carbodiimide modification,
uretonimine modification, trimer (isocyanurate) modification or a
combination thereof, so long as the modified polyisocyanate still
contains free isocyanate groups available for further reaction, or
(iii) the product formed by reaction of a polyisocyanate base with
a compound having nucleophilic functional groups capable of
reacting with an isocyanate group. Exemplary compounds containing a
nucleophilic functional group capable of reacting with an
isocyanate group include a polypeptide (for example, one or more of
the protein fractions described herein), a polyol, an amine based
polyol, an amine containing compound, a hydroxy containing
compound, carboxylic acid containing compound, carboxylate salt
containing compound, or a combination thereof. The term
"polyisocyanate" refers to difunctional isocyanate species, higher
functionality isocyanate species, and mixtures thereof.
[0147] One desirable feature of an isocyanate-based prepolymer is
that the prepolymer remain stable enough for storage and use,
desirably liquid and of reasonable viscosity at ambient
temperatures (25.degree. C.), and contains free isocyanate (--NCO)
groups which can participate in forming adhesive bonds.
[0148] As noted above, the organic polyisocyanate can be prepared
from a "base polyisocyanate." The term "base isocyanate" as used
herein refers to a monomeric or polymeric compound containing at
least two isocyanate groups. The particular compound used as the
base polyisocyanate can be selected so as to provide an adhesive
having certain desired properties. For example, base polyisocyanate
can be selected based on the number-average isocyanate
functionality of the compound. For example, in certain embodiments,
the base polyisocyanate can have a number-average isocyanate
functionality of 2.0 or greater, or greater than 2.1, 2.3 or 2.4.
In certain embodiments, the reactive group functionality of the
polyisocyanate component ranges from greater than 1 to several
hundred, 2 to 20, or 2 to 10. In certain other embodiments, the
reactive group functionality of the polyisocyanate component is at
least 1.9. In certain other embodiments, the reactive group
functionality of the polyisocyanate component is about 2. Typical
commercial polyisocyanates (having an isocyanate group
functionality in the range of 2 to 3) may be pure compounds,
mixtures of pure compounds, oligomeric mixtures (an important
example being polymeric MDI), and mixtures of these.
[0149] Useful base polyisocyanates have, in one embodiment, a
number average molecular weight of from about 100 to about 5,000
g/mol, from about 120 to about 1,800 g/mol, from about 150 to about
1,000 g/mol, from about 170 to about 700 g/mol, from about 180 to
about 500 g/mol, or from about 200 to about 400 g/mol. In certain
other embodiments, at least 80 mole percent or, greater than 95
mole percent of the isocyanate groups of the base polyisocyanate
composition are bonded directly to an aromatic group. In certain
embodiments, the adhesives described herein have a concentration of
free organically bound isocyanate (--NCO) groups in the range of
from about 5% to 35% (wt/wt), about 7% to 31% (wt/wt), 10% to 25%
(wt/wt), 10% to 20% (wt/wt), 15% to 27% (wt/wt).
[0150] In certain embodiments, the base polyisocyanate is an
aromatic polyisocyanate, such as p-phenylene diisocyanate;
m-phenylene diisocyanate; 2,4-toluene diisocyanate; 2,6-toluene
diisocyanate; naphthalene diisocyanates; dianisidine diisocyanate;
polymethylene polyphenyl polyisocyanates; 2,4'-diphenylmethane
diisocyanate (2,4'-MDI); 4,4'-diphenylmethane diisocyanate
(4,4'-MDI); 2,2'-diphenylmethane diisocyanate (2,2'-MDI);
3,3'-dimethyl-4,4'-biphenylenediisocyanate; mixtures of these; and
the like. In certain embodiments, polymethylene polyphenyl
polyisocyanates (MDI series polyisocyanates) having a number
averaged functionality greater than 2 are utilized as the base
polyisocyanate.
[0151] In certain embodiments, the MDI base polyisocyanate
comprises a combined 2,4'-MDI and 2,2'-MDI content of less than
18.0%, less than 15.0%, less than 10.0%, or less than 5.0%.
[0152] In certain other embodiments, the MDI diisocyanate isomers,
mixtures of these isomers with tri- and higher functionality
polymethylene polyphenyl polyisocyanates, the tri- or higher
functionality polymethylene polyphenyl polyisocyanates themselves,
and non-prepolymer derivatives of MDI series polyisocyanates (such
as the carbodiimide, uretonimine, and/or isocyanurate modified
derivatives) are utilized as polyisocyanates for use as the base
polyisocyanate. In certain other embodiments, the base
polyisocyanate composition comprises an aliphatic polyisocyanate
(e.g., in a minor amount), e.g., an aliphatic polyisocyanate
comprising an isophorone diisocyanate, 1,6-hexamethylene
diisocyanate, 1,4-cyclohexyl diisocyanate, or saturated analogues
of the above-mentioned aromatic polyisocyanates, or mixtures
thereof.
[0153] In certain other embodiments, the base polyisocyanate
comprises a polymeric polyisocyanate, e.g., a polymeric
diphenylmethane diisocyanate (polymethylene polyphenyl
polyisocyanate) species of functionality 3, 4, 5, or greater. In
certain embodiments, the polymeric polyisocyanates of the MDI
series comprise RUBINATE-M.RTM. polyisocyanate, or a mixture of MDI
diisocyanate isomers and higher functionality oligomers of the MDI
series. In certain embodiments, the base polyisocyanate product has
a free --NCO content of about 31.5% by weight and a number averaged
functionality of about 2.7.
[0154] In certain embodiments, the isocyanate group terminated
prepolymers are urethane prepolymers. These can be produced by
reaction of a hydroxyl-functional compound with an isocyanate
functional compound. In certain other embodiments, allophanate
prepolymers are utilized. Allophanate prepolymers typically require
higher temperatures (or allophanate catalysts) to facilitate
reaction of the polyol with the polyisocyanate to form the
allophanate prepolymer.
[0155] Polyisocyanates used in the compositions described can have
the formula R(NCO).sub.n. where n is 2 and R can be an aromatic, a
cycloaliphatic, an aliphatic, each having from 2 to about 20 carbon
atoms. Examples of polyisocyanates include, but are not limited to,
diphenylmethane-4,4'-diisoeyanate (MDI), toluene-2,4-diisocyanate
(TDI), toluene-2,6-diisocyanate (TDI), methylene
bis(4-cyclohexylisocyanate (CHMDI),
3-isocyanatomethyl-3,5,5-trimethyl-cyclohexyl isocyanate (IPDI),
1,6-hexane diisocyanate (HDI), naphthalene-1,5-diisocyanate (NDI),
1,3- and 1,4-phenylenediisocyanate,
triphenyImethane-4,4',4''-triisocyanatc, polymeric diphenylmethane
diisocyanate (PMDI), m-xylene diisocyanate (XDI), 1,4-cyclohexyl
diisocyanate (CHDI), isophorone diisocyanate, isomers, dimers,
trimers and mixtures or combinations of two or more thereof. The
term "PMDI" encompasses PMDI mixtures in which monomeric MDI, for
example 4,4'-, 2,2'- and/or 2,4'-MDI, is present. PMDI is, in one
embodiment, prepared by phosgenation of the corresponding PMDA in
the presence of an inert organic solvent. PMDA is in turn obtained
by means of an acid aniline-formaldehyde condensation which can be
carried out industrially either continuously or batchwise. The
proportions of diphenylmethanediamines and the homologous
polyphenylpolymethylenepolyamines and their positional isomerism in
the PMDA are controlled by selection of the ratios of aniline,
formaldehyde and acid catalyst and also by means of a suitable
temperature and residence time profile. High contents of
4,4'-diphenylmethanediamine together with a simultaneously low
proportion of the 2,4' isomer of diphenylmethanediamine are
obtained on an industrial scale by the use of strong mineral acids
such as hydrochloric acid as catalyst in the aniline-formaldehyde
condensation.
[0156] The epoxy-based prepolymer can be an epoxide containing
compound. Alternatively, the epoxy-based prepolymer can be a
reaction product between an epoxy and a polypeptide, a polyol, an
amine based polyol, an amine containing compound, a hydroxy
containing compound, or a combination thereof.
[0157] In certain embodiments, the composition is an epoxy resin
comprising free epoxy groups. Alternatively, the epoxy resin
composition is prepared by combining a precursor epoxy resin
composition with the isolated and fractionated polypeptide
compositions described herein. The epoxy resin composition can
comprise derivatives of digested proteins as described herein.
[0158] Epoxy resins refer to molecular species comprising two or
more epoxide (oxirane) groups per molecule. Epoxy resins can
contain mono-epoxides as reactive diluents, but the main
constituents by weight of such resins are still di and/or higher
functionality species (containing two or more epoxide groups per
molecule).
[0159] Epoxy resins useful as precursor epoxy resins can include
those which comprise difunctional epoxide and/or higher
functionality polyepoxide species. Precursor epoxy resins include
but are not limited to diglycidyl ether of bisphenol-A, diglycidyl
ethers of bisphenol-A alkoxylates, epoxy novolac resins,
expoxidized soy oil, epoxidized linseed oil, epichlorohydrin, a
glycidyl ether type epoxy resin derived from a polyphenol by
reaction with epichlorohydrin, and combinations thereof. In another
embodiment, precursor epoxy resins are modified by combining them
with the polypeptide compositions described herein, either in bulk
or in aqueous suspension.
[0160] The modified epoxy resins can be used in multi-part
mixing-activated adhesive formulations. Alternatively, multi-part
formulations can comprise polyisocyanates and/or known amine based
epoxy curatives as additional components. Alternatively, modified
epoxy resins can be used with any cure catalysts or other additives
known in the epoxy resin art. The polypeptide compositions
described herein contain functional groups which react with epoxide
groups in the epoxy resin. The extent of this reaction depends upon
the preparative conditions, use or non-use of catalysts, the
specific resins and protein component described herein selected,
etc.
[0161] An important subset of epoxy resins can be made by reacting
a precursor polyol with an epihalohydrin, such as epichlorohydrin.
The products of the reaction are called glycidyl ethers (or
sometimes as polyglycidyl ethers or diglycidyl ethers). In certain
embodiments, all the hydroxyl groups in the precursor polyols are
converted to the corresponding glycidyl ethers.
[0162] An important class of glycidyl ether type epoxy resins are
derived from polyphenols, by reaction with epichlorohydrin. The
starting polyphenols are di- or higher functionality phenols.
Industrially important examples of this type of epoxy resin
comprise, for example, diglycidyl ether of bisphenol-A (also known
as DGEB-A); diglycidyl ether of 2,6,2',6'-tetrachloro bisphenol A;
diglycidyl ether of bisphenol-F (DGEB-F); epoxidized novolac
resins; mixtures of these, and the like.
[0163] Partially or fully saturated (hydrogenated) analogs of these
epoxy resins may also be used. A non limiting example of a known
saturated epoxy resin of this type is DGEB-H, which is the fully
hydrogenated (ring saturated) aliphatic analog of DGEB-A.
[0164] Amines, which contain active hydrogen atoms may also be
reacted with epichlorohydrin to form epoxy resins. Examples of
these types of resins include, for example, N,N,N',N'-tetraglycidyl
diphenylmethane diamine (such as the 4,4' isomer);
p-glycidyloxy-N,N-diglycidylaniline; N,N-diglycidylaniline;
mixtures of these; and the like.
[0165] Heterocyclic nitrogen compounds that contain active hydrogen
atoms may likewise be converted into the corresponding epoxy resins
by reaction with epichlorohydrin. Non limiting examples of such
resins include, for example, N,N',N''-triglycidyl isocyanurate;
N,N'-diglycidyl-5,5-dimethylhydantoin; mixtures of these; and the
like.
[0166] Many other kinds of epoxy resins are known which are not
made by reaction of an active hydrogen precursor with an
epihalohydrin. Non-limiting examples of these types of epoxy
resins, known in the art, include, for example, dicyclopentadiene
diepoxide (also known as DCPD dioxide), vinycyclohexene diepoxide
(dioxide), epoxidized polyunsaturated vegetable oils (such as
epoxidized linseed oil, epoxidized soy oil, etc.), epoxidized
polydiene resins (such as epoxidized polybutadienes),
3,4-epoxy-6-methyl cyclohexylmethyl-3,4-epoxy-6-methyl cyclohexane
carboxylate, mixtures of these, and the like. In principle, any
precursor molecule which contains two or more units of reactive
aliphatic "C.dbd.C" unsaturation per molecule might be converted
into an epoxy resin.
[0167] It should be understood that any of the base epoxy resins
known in the art, such as those listed above, are frequently
modified with diluents, flexibilizers, and/or other additives. The
optional possibility of using one or more known art modifiers or
additives, in addition to the required protein derivatives, is
within the level of skill in the art. Those skilled in the art of
formulating adhesive systems using epoxy resins will appreciate how
and when to use known optional additives and modifiers.
[0168] In addition, the prepolymers can include one, two or more
polyol compounds. Exemplary polyol compounds include an amine
alkoxylate, polyoxypropylene glycol, propylene glycol,
polyoxyethylene glycol, polytetramethylene glycol, polyethylene
glycol, propane diol, glycerin, or a mixture thereof.
[0169] Polyols useful in preparing the adhesives described herein
include all known polyols, for example, polyols used in the
polyurethanes art. In certain embodiments, the polyol comprises
primary and/or secondary hydroxyl (i.e., --OH) groups. In certain
other embodiments, the polyol comprises at least two primary and/or
secondary hydroxyl (i.e., --OH) groups per molecule. Mono
functional alcohols (such as aliphatic alcohols, aromatic alcohols,
or hydroxyl functional monomers such as hydroxyl functional
acrylates (to yield UV or thermally curable materials) can be used
to cap an isocyanate group. In certain other embodiments, the
polyol comprises a hydroxyl (i.e., --OH) group functionality
between 1.6 and 10, between 1.7 to 6, between 2 to 4, or between 2
to 3. In certain other embodiments, the weight average molecular
weight range for the optional polyols is from 100 to 10,000 g/mol,
from 400 to 6,000 g/mol, or from 800 to 6,000 g/mol.
[0170] In certain other embodiments, useful polyols are polyester
polyols or polyether polyols, such as an aliphatic polyether
polyol. One exemplary aliphatic polyether polyol is
polyoxypropylene glycol, with a number average molecular weight in
the range of from 1,500 to 2,500 g/mol.
[0171] In certain embodiments, the total amount of all polyol, or
polyols, in the isocyanate reactive component is from 1% to 80%, or
from 3% to 70%, or from 5% to 60% by weight of the total.
[0172] In certain other embodiments, alkanolamines comprising
primary, secondary, and/or tertiary amine groups can be used.
[0173] In certain embodiments, useful water-dispersible polymer
latexes can include latexes of polymethylmethacrylate and its
copolymers, latexes of polymethacrylate and its copolymers, latexes
of polyvinylchloride and its copolymers, latexes of
polyvinylacetate and its copolymers, polyvinyl alcohol and its
copolymers, etc.
[0174] Further, as discussed above, the prepolymer species can
comprise a terminated isocyanate. Here, for example, a polyol is
reacted with the base polyisocyanate composition prior to or during
mixing with the polypeptide fractions herein. Those skilled in the
art will recognize many variations on the use of optional
prepolymers in preparing wood adhesive compositions.
[0175] The amount of reactive prepolymer used in the adhesive
compositions can be selected based on the desired properties of the
adhesive composition. For example, when optimizing the viscosity of
a one-part adhesive, the ratio of prepolymer (e.g., PMDI, Epoxy and
the like) to protein component (i.e., ground plant meal or isolated
polypeptide composition) can be from about 10:1 and 4:1 in order to
form an adhesive composition that is relatively less viscous.
Alternatively, for a two-part adhesive, the ratio of prepolymer
(e.g., PMDI, Epoxy and the like) to protein component can be from
about 1:20 to 3:2.
IV. Additives
[0176] One or more additives can be included in the adhesive
composition in order to achieve particular performance properties.
Exemplary additives include an intercalated clay, partially
exfoliated clay, exfoliated clay, cellulose nanoparticles,
catalysts, tacking agents, extenders, fillers, viscosifying agents,
surfactants, adhesion promoters, antioxidants, antifoaming agents,
antimicrobial agents, antibacterial agents, fungicides, pigments,
inorganic particulates, gelling agents, cross-linking agents,
agents that improve moisture resistance, pH modulators,
composite-release promoters, formaldehyde scavenging agents, fire
retardants, and wood preservatives.
[0177] In certain embodiments, the additive is a water-dispersible
additive or a water-soluble additive. Water-soluble additives
include hydroxyl-functional or amine-functional compounds (such as
glycerin, propylene glycol, polypropylene glycol, polyethylene
glycol, trimethylol propane and its adducts, phenols, polyphenols,
etc.). One benefit of using glycerin and various low-viscosity
polyols is that they allow less water to be used in the adhesive
composition. Reducing the amount of water, while retaining a
low-viscosity adhesive composition, desirably reduces the risk that
the composite formed therefrom is damaged by steam generated during
formation of the composite at high temperature.
[0178] In certain other embodiments, the additive is a non-volatile
(e.g., having a boiling point of greater than about 180.degree. C.
at 760 mmHg), inert viscosity-reducing diluent. In yet other
embodiments, the additive is an antioxidant, antifoaming agent,
anti-bacterial agent, fungicide, pigment, viscosifying agent,
gelling agent, aereosolozing agent, inorganic particulate (e.g.,
titanium dioxide, yellow iron oxide, red iron oxide, black iron
oxide, zinc oxide, aluminum oxide, aluminum trihydrate, calcium
carbonate), clay such as montmorillonite, a wetting agent, and the
like.
[0179] In certain embodiments, the additive is an agent that
improves moisture-resistance. In certain other embodiments, the
additive is a composite-release promoter (such as a
composite-release promoter selected from the group consisting of a
C.sub.10-25 alkanoic acid, a salt of a C.sub.10-25 alkanoic acid, a
C.sub.10-25 alkenoic acid, a salt of an C.sub.10-25 alkenoic acid,
and a silicone). In certain other embodiments, the additive is a pH
modulator. In certain other embodiments, the additive is a fire
retardant or wood preservative. In certain other embodiments, the
additive is a fire retardant, wood preservative, antimicrobial
agent, antibacterial agent, or fungicide, any of which may be in
the form of nanoparticles.
[0180] In certain embodiments, each additive present in the
adhesive composition is independently present in an amount ranging
from 0.1% (w/w) to about 20% (w/w), from 0.1% (w/w) to about 10%
(w/w), from 0.5% (w/w) to about 3% (w/w), from 1% (w/w) to about
20% (w/w), from 1% (w/w) to about 10% (w/w), from 1% (w/w) to about
5% (w/w), from 1% (w/w) to about 3% (w/w), or from 5% (w/w) to
about 10% (w/w). In certain other embodiments, such as where the
additive is a fire retardant, the additive may be present in the
adhesive composition in an amount ranging from about 1% (w/w) to
about 40% (w/w), from about 10% (w/w) to about 40% (w/w), from
about 20% (w/w) to about 40% (w/w), or from about 25% (w/w) to
about 35% (w/w).
[0181] Exemplary classes of additives are described in more detail
in the sections below.
Intercalated Clay
[0182] Intercalated clays can be obtained from commercial sources
or prepared by exposing a clay to an intercalating agent. Exemplary
types of clay that may be converted to intercalated form include,
for example, smectite clays, illite clays, chlorite clays, layered
polysilicates, synthetic clays, and phyllosilicates. Exemplary
specific clays that may be converted to intercalated form include,
for example, montmorillonite (e.g., sodium montmorillonite,
magnesium montmorillonite, and calcium montmorillonite),
beidellite, pyrophyllite, talc, vermiculite, sobockite, stevensite,
svinfordite, sauconite, saponite, volkonskoite, hectorite,
nontronite, kaolinite, dickite, nacrite, halloysite, hisingerite,
rectorite, tarosovite, ledikite, amesite, baileychlore, chamosite,
clinochlore, kaemmererite, cookeite, corundophilite, daphnite,
delessite, gonyerite, nimite, odinite, orthochamosite, penninite,
pannantite, rhipidolite, prochlore, sudoite, thuringite, kanemite,
makatite, ilerite, octosilicate, magadiite, and kenyaite. In
certain embodiments, the clay converted to intercalated form is
montmorillonite.
[0183] Exemplary intercalating agents include, for example,
quaternary amine compounds (such as a tetra-alkylammoniun salt),
polymers (e.g., a polycaprolactone, maleated polyethylene, or
maleated polypropylene) an acrylic monomer, phosphonium compounds,
arsonium compounds, stibonium compounds, oxonium compounds,
sulfonium compounds, polypropene, fatty acid esters of
pentaerythritol, a steroyl citric acid ester, and alcohols (such as
aliphatic alcohols, aromatic alcohols (e.g., phenols), aryl
substituted aliphatic alcohols, alkyl substituted aromatic
alcohols, and polyhydric alcohols).
[0184] Intercalated clays can be characterized by, for example, the
following physical properties: interlayer spacing, d-spacings, clay
particle size, particle size distribution, peak degradation
temperature, and thickness of layers. Exemplary physical property
features for intercalated clays contemplated to be amenable for use
in the present invention include, for example, one or more of the
following: (i) an intercalated clay having an interlayer spacing of
about 0.5 .ANG. to about 100 .ANG. (or about 1 .ANG. to about 20
.ANG.), (ii) a mean particle size of about 1 .mu.m to about 150
.mu.m (or about 20 .mu.m to about 100 .mu.m), (iii) a particle size
distribution where about 90 percent to about 50 percent of the
intercalated clay particles have a particle size of from about 20
.mu.m to about 100 .mu.m (or about 85 percent to about 65 percent
of the intercalated clay particles have a particle size of about 20
.mu.m to about 100 .mu.m), (iv) a peak degradation temperature of
about 200.degree. C. to about 600.degree. C. (or from about
300.degree. C. to about 500.degree. C.), and/or (v) layers in the
intercalated clay have a thickness of about 0.5 .ANG. to about 100
.ANG. (or about 5 .ANG. to about 50 .ANG.).
[0185] In certain other embodiments, the intercalated clay is
intercalated montmorillonite having a particle size of less than
about 500 nm, or less than about 100 nm. In certain other
embodiments, the intercalated clay is intercalated montmorillonite
having a particle size of about 60 nm to about 400 nm.
[0186] The clay (e.g., an intercalated clay) may be surface treated
with an organic compound, such as a hydrophobic organic compound or
hydrophilic organic compound, in order to promote dispersion of the
clay in a formulation, such as an adhesive composition described
herein. Surface treatment methods and compositions are described in
the literature and are contemplated to be amenable for use in the
present invention.
[0187] Different intercalated clays may impart different
performance properties to the adhesive composition. Accordingly, in
certain embodiments, the intercalated clay is an intercalated
smectite. In certain other embodiments, intercalated clay is a
smectite that has been intercalated with a quaternary ammonium
compound. In certain other embodiments, the intercalated clay is an
intercalated montmorillonite. In yet other embodiments, the
intercalated clay is montmorillonite intercalated with a
dimethyl-di(C.sub.14-C.sub.18)alkyl ammonium salt.
Exfoliated Clay & Partially Exfoliated Clay
[0188] Exfoliated clay or a partially exfoliated clay can be
prepared by exposing an intercalated clay to exfoliation conditions
using procedures described in the literature. One procedure for
preparing a partially exfoliated clay is to subject an intercalated
clay to high shear mixing and/or sonication (e.g., using
ultrasound) until the intercalated clay has partially exfoliated.
The procedure may be performed by placing the intercalated clay
(e.g., quaternary amine intercalated montmorillonite) in a
hydrophobic liquid medium (such as mineral oil, soy oil, castor
oil, silicone oil, a terpene (e.g., limonene), plant oil alkyl
esters (e.g., soy methyl ester and canola methyl ester), mixtures
thereof (e.g., a mixture of a silicone oil and limonene), etc.) to
form a mixture, and then subjecting the mixture to high shear
mixing and/or ultrasound until the intercalated clay has partially
exfoliated. Partial exfoliation occurs when clay platelets separate
from the intercalated clay particles. Partial exfoliation can be
observed macroscopically in many instances because it can cause a
low viscosity mixture of intercalated clay and hydrophobic liquid
medium to form a gel. This gel can be added to protein adhesives or
components used to form a protein adhesive described herein.
Alternatively, the intercalated clay may be added to a protein
adhesive composition, and the protein adhesive composition is
subjected to exfoliation conditions to generate the partially
exfoliated clay in situ.
[0189] An exfoliated clay can be prepared by exposing an
intercalated clay to high shear mixing and/or sonication (e.g.,
using ultrasound) until substantially all (e.g., greater than 90%
w/w, 95% w/w, or 98% w/w) the intercalated clay has exfoliated. The
exfoliation procedure can be performed by placing the intercalated
clay (e.g., quaternary amine intercalated montmorillonite) in a
hydrophobic liquid medium (such as mineral oil, soy oil, castor
oil, silicone oil, a terpene (e.g., limonene), plant oil alkyl
esters (e.g., soy methyl ester and canola methyl ester), mixtures
thereof (e.g., a mixture of a silicone oil and limonene), etc.) to
form a mixture, and then subjecting the mixture to high shear
mixing and/or sonication (e.g., using ultrasound) until
substantially all (e.g., greater than 90% w/w, 95% w/w, or 98% w/w)
the intercalated clay has exfoliated. Alternatively, the
intercalated clay may be added to a protein adhesive composition,
and the protein adhesive composition is subjected to exfoliation
conditions to generated the exfoliated clay in situ. Alternatively,
a clay (such as sodium montmonilonite) may be added to an adhesive
composition, together with a quaternary ammonium compound, and
optionally together with a satisfactory oil carrier (e.g., one that
has the ability to solvate the quaternary compound), and the
resulting adhesive composition is subjected to conditions to
intercalate the clay and to generated the exfoliated clay or
partially exfoliated clay in situ. In addition, if so desired, the
quaternary ammonium compound can be pre-dissolved in the oil
carrier before it is added to the adhesive composition together
with a clay.
[0190] Exemplary partially exfoliated clays contemplated to be
amenable for use in present invention include partially exfoliated
forms of smectite clay, illite clay, chlorite clay, layered
polysilicates, synthetic clay, and phyllosilicates. Exemplary
specific partially exfoliated clays contemplated to be amenable for
use in present invention include partially exfoliated forms of, for
example, montmorillonite (e.g., sodium montmorillonite, magnesium
montmorillonite, and calcium montmorillonite), beidellite,
pyrophyllite, talc, vermiculite, sobockite, stevensite,
svinfordite, sauconite, saponite, volkonskoite, hectorite,
nontronite, kaolinite, dickite, nacrite, halloysite, hisingerite,
rectorite, tarosovite, ledikite, amesite, baileychlore, chamosite,
clinochlore, kaemmererite, cookeite, corundophilite, daphnite,
delessite, gonyerite, nimite, odinite, orthochamosite, penninite,
pannantite, rhipidolite, prochlore, sudoite, thuringite, kanemite,
makatite, ilerite, octosilicate, magadiite, and kenyaite. In
certain embodiments, the partially exfoliated clay is partially
exfoliated clay montmorillonite.
[0191] A partially exfoliated clay can be characterized by, for
example, the amount of clay particles that are in the form of
platelets. In certain embodiments, about 0.1% w/w to about 40% w/w,
about 0.1% w/w to about 20% w/w, about 0.1% w/w to about 10% w/w,
about 0.1% w/w to about 5% w/w, about 5% w/w to about 20% w/w of
the clay particles are in the form of platelets. In certain
embodiments, about 0.1% w/w to about 40% w/w of the clay particles
are in the form of platelets having a size of about 1 .ANG. to
about 50 .ANG., about 30 .ANG. to about 50 .ANG., or about 5 .ANG.
to about 20 .ANG..
[0192] Exemplary exfoliated clays contemplated to be amenable for
use in present invention include exfoliated forms of smectite clay,
illite clay, chlorite clay, layered polysilicates, synthetic clay,
and phyllosilicates. Exemplary specific exfoliated clays
contemplated to be amenable for use in present invention include
exfoliated forms of, for example, montmorillonite (e.g., sodium
montmorillonite, magnesium montmorillonite, and calcium
montmorillonite), beidellite, pyrophyllite, talc, vermiculite,
sobockite, stevensite, svinfordite, sauconite, saponite,
volkonskoite, hectorite, nontronite, kaolinite, dickite, nacrite,
halloysite, hisingerite, rectorite, tarosovite, ledikite, amesite,
baileychlore, chamosite, clinochlore, kaemmererite, cookeite,
corundophilite, daphnite, delessite, gonyerite, nimite, odinite,
orthochamosite, penninite, pannantite, rhipidolite, prochlore,
sudoite, thuringite, kanemite, makatite, ilerite, octosilicate,
magadiite, and kenyaite. In certain embodiments, the exfoliated
clay is an exfoliated smectite. In certain embodiments, the
exfoliated clay is exfoliated montmorillonite.
[0193] An exfoliated clay can be characterized by, for example, the
size of platelets and the aspect ratio of platelets. In certain
embodiments, the size of the platelets is about 1 .ANG. to about 50
.ANG., about 30 .ANG. to about 50 .ANG., or about 5 .ANG. to about
20 .ANG.. In certain embodiments, the aspect ratio of the platelets
is about 100 to about 10,000, about 100 to about 5,000, or about
200 to about 2,000. In certain other embodiments, the exfoliated
clay has a mean particle size of less than about 500 nm, less than
100 nm, or less than 25 nm. In certain other embodiments, the
exfoliated clay has a mean particle size of from about 60 nm to
about 400 nm, about 50 nm to about 300 nm, about 40 nm to about 200
nm, or about 20 nm to about 150 nm.
[0194] In certain other embodiments, a partially exfoliated clay is
formed by exposing a clay to an effective amount of a protein
component (e.g., ground plant meal or an isolated polypeptide
composition) to form a mixture and subjecting the mixture to
exfoliation conditions, such as high shear mixing and/or
sonication. In certain other embodiments, an exfoliated clay is
formed by exposing a clay to an effective amount of protein
component (e.g., ground plant meal or an isolated polypeptide
composition to form a mixture and subjecting the mixture to
exfoliation conditions, such as high shear mixing and/or
sonication.
Cellulose Nanoparticles
[0195] Cellulose nanoparticles can be added to the adhesive
composition to achieve certain performance properties, such as to
provide an adhesive with increased toughness and/or bond strength.
Cellulose nanoparticles can be obtained from commercial sources or
isolated from plant-based fibers by acid-hydrolysis. Cellulose
nanoparticles can be characterized by, for example, the size of the
nanoparticle, the cross-sectional shape of the nanoparticle, and
the cross-sectional length and aspect ratio of the nanoparticle.
Accordingly, in certain embodiments, the cellulose nanoparticle has
a size of from about 1 nm to about 2000 nm, about 10 nm to about
1000 nm, about 10 nm to about 500 nm, or about 10 nm to about 200
nm. In certain embodiments, the cross-sectional shape of the
nanoparticle may be triangular, square, pentagonal, hexagonal,
octagonal, circular, or oval. In certain other embodiments, the
average cross-sectional length of the cellulose nanoparticle is
about 0.1 nm to about 100 nm, or about 1 nm to about 10 nm.
[0196] One type of cellulose nanoparticles that may provide certain
advantages are cellulose nanofibers. Exemplary cellulose nanofibers
are described in, for example, U.S. Patent Application Publication
Nos. 2010/0233481, 2010/0240806, and 2010/0282422, each of which is
hereby incorporated by reference.
Catalyst
[0197] A catalyst may be added to the adhesive composition to
facilitate polymerization. Exemplary catalysts include, for
example, a primary amine, a secondary amine, a tertiary amine, an
organometallic compound, or a combination thereof. Exemplary
primary amines include, for example, methylamine, ethylamine,
propylamine, cyclohexylamine, and benzylamine Exemplary secondary
amines include, for example, dimethylamine, diethylamine, and
diisopropylamine. Exemplary tertiary amines include, for example,
diazabicyclooctane (Dabco), triethylamine, dimethyl benzylamine,
bis-dimethylaminoethyl ether, tetramethyl guanidine,
bis-dimethylaminomethyl phenol, 2,2'-dimorpholinodiethyl ether,
2-(2-dimethylaminoethoxy)-ethanol,
2-dimethylaminoethyl-3-dimethylaminopropyl ether,
bis-(2-diaminoethyl)-ether, N,N-dimethyl piperazine,
N-(2-hydroxyethoxyethyl)-2-azanorbornane, Tacat DP-914 (Texaco
Chemical), Jeffcat.RTM., N,N,N,N-tetramethyl butane-1,3-diamine,
N,N,N,N-tetramethyl propane-1,3-diamine, N,N,N,N-tetramethyl
hexane-1,6-diamine, 2,2'-dimorpholinodiethyl ether (DMDEE), or a
mixture thereof. Exemplary organometallic compounds include, for
example, di-n-octyl tin mercaptide, dibutyl tin maleate, diacetate,
dilaurate, dichloride, bis-dodecyl mercaptide, tin(II)acetate,
ethyl hexoate and diethyl hexoate, Fe.sup.+3 2,4-pentanedionate
(FeAcAc), or lead phenyl ethyl dithiocarbamate.
[0198] In certain other embodiments, the catalyst is a transition
metal acetylacetonates, e.g., an acetylacetonate compound
comprising iron, copper, or nickel. In certain embodiments, the
transition metal acetylacetonate comprises a tertiary amine, e.g.,
2,2'-dimorpholino diethyl ether.
[0199] The amount of catalyst used in the adhesive composition can
be varied in order to optimize the features of the adhesive. In
certain embodiments, the catalyst is present in less than 1%
(wt/wt), 0.5% (wt/wt), or 0.1% (wt/wt) of the adhesive composition.
In certain other embodiments, the catalyst is present in a range
from 0.001% (wt/wt) to 0.75% (wt/wt), 0.001% (wt/wt) to 0.01%
(wt/wt), 0.01% (wt/wt) to 0.05% (wt/wt), or 0.05% (wt/wt) to 0.5%
(wt/wt) of the adhesive composition.
Tacking Agent
[0200] Exemplary tacking agents include, for example, glycerin,
corn syrup, soy oil, a poly(C.sub.2-C.sub.6)alkylene, mineral oil,
an ethylene/propylene/styrene copolymer, a
butylene/ethylene/styrene copolymer, or a mixture of one or more of
the foregoing. Other exemplary tacking agents are copolymers that
have a low glass transition temperature (Tg) (e.g., a latex-based,
acrylic copolymer with a Tg of less than about 0.degree. C., and
preferably less than about -20.degree. C.). In certain embodiments,
the additive is polybutene. In certain embodiments, the polybutene
has a weight average molecular weight of from about 200 g/mol to
about 20,000 g/mol, from about 200 g/mol to about 10,000 g/mol,
from about 200 g/mol to about 5,000 g/mol, from about 200 g/mol to
about 2,000 g/mol, from about 200 g/mol to about 1,000 g/mol, from
about 500 g/mol to about 2,000 g/mol, or from about 500 g/mol to
about 1,000 g/mol. Other tacking agents include a solid selected
from the group consisting of a terpene resin, a rosin ester
derivative, and a hydrocarbon-based derivative. When the tacking
agent is a solid, the tacking agent may optionally be pre-dissolved
in an oil-phase of the adhesive composition (e.g., in PMDI).
Alternatively, the solid tacking agent can be pre-melted and
dispersed in water by means of the protein component, or the solid
tacking agent can be ground and dispersed as fine particulates
directly into the adhesive composition.
Extender
[0201] Exemplary extenders include, for example, inert extenders or
active extenders. In certain embodiments, the inert extender is
vegetable particulate matter, limonene, vegetable oil, mineral oil,
dibasic esters, propylene carbonate, non-reactive modified aromatic
petroleum hydrocarbons, soy oil, castor oil, and in general any
non-active hydrogen containing liquid that can be incorporated into
an isocyanate based adhesive. Another inert extender is any
non-active hydrogen containing solid that is soluble, e.g., soluble
in oil or soluble in water. The active extender can be a
pyrrolidone monomer or polymers, an oxizolidone monomer or
polymers, an epoxidized oil, or an unsaturated oil, such as linseed
oil. Another active extender is a vinyl monomer or mixture of vinyl
monomers.
Surfactants & Adhesion Promoters
[0202] Exemplary surfactants include, for example, monomeric types,
polymeric types, or mixtures thereof. Exemplary adhesion promoters
include, for example, organosilanes and titanates.
Antimicrobial Agent
[0203] Antimicrobial agents known in the art that do not
substantially react with PMDI are contemplated for use in the
adhesive compositions and composites described herein. One
exemplary antimicrobial agent is polyalkylene glycol polymers, such
as polypropylene glycol.
Crosslinking Agent
[0204] In other embodiments, the additive can be a crosslinking
agent, for example, a crosslinking agent that can be used to bond
lignocellulosic material to glass. Exemplary crosslinking agents
include an organosilane, such as dimethyldichlorosilane (DMDCS),
alkyltrichlorosilane, methyltrichlorosilane (MTCS),
N-(2-aminoethyl)-3-aminopropyl trimethoxysilane (AAPS), or a
combination thereof. In other embodiments the polypeptide fractions
are combined with an organosilane to form an adhesive for bonding
one or more substrates together in any combination, said substrates
including glass, paper, wood, ceramic, steel, aluminum, copper,
brass, etc. The term "organosilane" refers to any group of
molecules including monomers, hydrolyzed monomers, hydrolyzed
dimers, oligomers, and condensation products of a trialkoxysilane
having a general formula:
(RO).sub.3Si--R'
where R is preferably a propyl, ethyl, methyl, isopropyl, butyl,
isobutyl, sec-butyl, t-butyl, or acetyl group, and R' is an
organofunctional group where the functionality may include an
aminopropyl group, an aminoethylaminopropyl group, an alkyl group,
a vinyl group, a phenyl group, a mercapto group, a styrylamino
group, a methacryloxypropyl group, a glycidoxy group, an isocyante
group, or others.
[0205] Similarly, a bis-trialkoxysilane having the general formula
(RO).sub.3Si--R'--Si(OR).sub.3 can also be employed as an
"organosilane" either alone or in combination with a
trialkoxysilane, where R is preferably a propyl, ethyl, methyl,
isopropyl, butyl, isobutyl, sec-butyl, t-butyl, or acetyl group,
and R' is a bridging organofunctional residue which may contain
functionality selected from the group consisting of amino groups,
alky groups, vinyl groups, phenyl groups, mercapto groups, and
others. Similarly, a tetraalkoxysilane having the general formula
(RO).sub.4Si can also be employed as an "organosilane" either alone
or in combination with a trialkoxysilane, or a bis-trialkoxysilane,
where R is preferably a propyl, ethyl, methyl, isopropyl, butyl,
isobutyl, sec-butyl, t-butyl, or acetyl group.
Agent that Improves Moisture-Resistance
[0206] Agents that improve moisture-resistance refer to those
materials that, when added to adhesive compositions described
herein, improve the ability of a wood composite formed from the
adhesive to be resistant to water, i.e., not absorb water.
Exemplary types of agents that improve moisture resistance include
fluorinated polyol compounds, silicones, siloxanes (including
functionalized siloxane polymers, such as hydroxy-terminated
siloxane polymers or hydroxyl alkyl siloxane polymers), polyolefin
polymers, wax (e.g., fatty acids (such as an alkyl carboxylic
acid), salts of a fatty acid (e.g., an alkali metal salt of an
alkyl carboxylic acid), esters of a fatty acid (e.g., an alkyl
ester of a carboxylic acid, an aryl ester of a carboxylic acid, an
alkyl ester of an alkanoic acid, or an aryl ester of an alkanoic
acid), fatty alcohols, mixtures of hydrophobic hydrocarbons,
water-based emulsions containing hydrophobic hydrocarbons dispersed
therein, a hydrocarbon wax, a fluoroalkylphosphate wax, a
fluorinated hydrocarbon wax, and a fluoroalkyl functionalized wax),
and hydrophobic oils. Another agent that improves
moisture-resistance is a fluorinated silicone. When an agent that
improves moisture-resistance is present in an adhesive composition,
it is desirably present in an amount effective to increase moisture
resistance (e.g., an increase in moisture resistance of at least
about 2%, 5%, 10%, or 20% compared to the moisture resistance of a
composite formed from an adhesive composition lacking the agent
that improves moisture-resistance).
[0207] Agents that improve moisture-resistance may be present in
the final composite at a weight percent in the range of about 0.01%
(w/w) to about 5% (w/w), about 0.01% (w/w) to about 2% (w/w), about
0.01% (w/w) to about 1% (w/w), about 0.01% (w/w) to about 0.5%,
about 0.1% (w/w) to about 2% (w/w), (w/w), about 0.1% (w/w) to
about 1% (w/w), (w/w), about or 0.5% (w/w) to about 1% (w/w).
[0208] One exemplary fluorinated polyol compound is FluoroLink D-10
fluorinated polyol that is commercially available from Solvay
Solexis, Inc. Exemplary silicones include Dow Corning FS-1265
Fluid, 300 cST (Trifluoropropyl Methicone) from Dow Corning), and
T-Sil-6011 SE Emulsion (60% Solids), from Siovation, Inc. which is
a emulsion containing 60% w/w silicones. The silicone may be
organically modified, such as C.sub.20-24 Alkyl Methicone,
C.sub.24-28 Alkyl Methicone, C.sub.30-45 Alkyl Methicone, Stearyl
Dimethicone, Biphenyl Dimethicone, Stearoxy Dimethicone,
C.sub.20-24 Alkyl Dimethicone, or C.sub.24-28 Alkyl
Dimethicone.
[0209] Exemplary types of functionalized siloxane polymers include
(1) a hydroxy-terminated siloxane polymer such as
hydroxy-terminated polydimethylsiloxane (e.g., T-Sil-80, a linear
hydroxy terminated polydimethylsiloxane from Siovation, Inc.), (2)
a hydroxyl alkyl polydimethylsiloxane (e.g., Tego Protect-5000
functionalized silicone fluid commercially available from Evonik
Tego Chemie GmbH), and (3) a fluorinated siloxane. Exemplary waxes
include Hexion EW-58H; BE Square 165 Amber Petroleum
Microcrystalline Wax commercially available from Baker Hughes,
Inc., which is a mixture comprising paraffinic, isoparaffinic, and
naphthenic hydrocarbons; Masurf FS 115 Emulsion (a
fluoroalkylphosphate wax dispersion in water--28% Solids)
commercially available from Mason Chemical Company; camauba wax;
candelilla wax; japan wax; beeswax; rice bran wax; montan wax;
paraffin; ceresin; lanolin; ozokerita; slack wax (which is
semi-refined wax having an oil content up to about 30 mass percent,
and often produced by chilling and solvent filter-pressing wax
distillate); polyethylene wax; a fatty acid or salt thereof (e.g.,
C.sub.10-25 alkanoic acid, a salt of a C.sub.10-25 alkanoic acid, a
C.sub.10-25 alkenoic acid, a salt of an C.sub.10-25 alkenoic acid;
such as stearic acid, zinc stearate, or lauric acid), a fatty ester
(e.g., an ester of an C.sub.10-25 alkanoic acid or C.sub.10-25
alkenoic acid); or fatty alcohol (e.g., C.sub.10-25 hydroxy alkane
or C.sub.10-25 hydroxy alkene).
[0210] Exemplary hydrophobic polymers include a polyolefin (e.g.,
polyethylene, polypropylene, polybutylene, polystyrene, copolymers
of the foregoing, polyethylene/polyvinyl acetate copolymer, and
polyethylene/polyacrylic acid copolymer).
[0211] Exemplary hydrophobic oils include soy lecithin, caster oil,
and a fluorinated hydrocarbon liquid.
[0212] Another agent that improves moisture resistance is a mixture
of a silicone and a terpene compound. An exemplary silicone is Tego
Protect-5000 functionalized silicone fluid sold by Evonik Tego
Chemie GmbH. Exemplary terpene compounds contemplated for use
include terpene compounds that are a solid at room temperature, a
liquid at room temperature, and/or have a molecular weight of less
than about 2000 g/mol, about 1000 gmol, about 500 g/mol, or about
200 g/mol. In certain embodiments, the terpene compound is
limonene. In certain embodiments, the agent that improves moisture
resistance is a mixture of Tego Protect-5000 functionalized
silicone fluid and limonene.
[0213] In certain embodiments, the agent that improves
moisture-resistance is a polymer agent that improves
moisture-resistance, a wax agent that improves moisture-resistance,
or a mixture thereof. In certain other embodiments, the agent that
improves moisture-resistance is a silicone, a siloxane, a
fluorinated polyol, a fluoroalkyl phosphate ester, a fluoroalkyl
carboxylic ester, a salt of a fluoroalkanoic acid, a wax that
improves moisture-resistance, or a mixture thereof. In certain
other embodiments, the agent that improves moisture-resistance is a
wax that improves moisture-resistance, such as a mixture of
hydrophobic hydrocarbons, water-based emulsions containing
hydrophobic hydrocarbons dispersed therein, a fluoroalkylphosphate
wax, a fluorinated hydrocarbon wax, or a fluoroalkyl functionalized
wax. In certain other embodiments, the agent that improves
moisture-resistance is a silicone, a siloxane, a fluorinated
polyol, a fluoroalkyl phosphate ester, or a fluoroalkyl carboxylic
ester. In certain other embodiments, the agent that improves
moisture-resistance is a silicone, a siloxane, a fluorinated
polyol, a fluoroalkyl phosphate ester, a fluoroalkyl carboxylic
ester, a salt of a fluoroalkanoic acid, or a mixture thereof. In
certain other embodiments, the agent that improves
moisture-resistance is a silicone, a siloxane, a fluorinated
polyol, a fluoroalkyl phosphate ester, a fluoroalkyl carboxylic
ester, or a wax that improves moisture-resistance. In certain other
embodiments, the agent that improves moisture-resistance is a
fluorinated polyol, a silicone, a siloxane, or wax that improves
moisture-resistance. In yet other embodiments, the agent that
improves moisture-resistance is a mixture comprising hydrophobic
hydrocarbons.
[0214] The term "fluoroalkyl phosphate ester" as used herein refers
to a compound comprising a phosphate group bonded to at least one
fluoroalkyl group, such as represented by
P(O)(OR.sup.1)(OR.sup.2).sub.2, wherein R.sup.1 is a fluoroalkyl
group, and R.sup.2 represents independently for each occurrence
hydrogen, alkyl, fluoroalkyl, aryl, aralkyl, heteroalkyl,
heteroaryl, heteroaralkyl, an alkali metal, ammonium, or a
quaternary amine, or two occurrences of R.sup.2 are taken together
to form an alkaline earth metal.
pH Modulator
[0215] The pH modulator can be an acid or base. In certain
embodiments, the pH modulator is an alkali metal hydroxide (e.g.,
sodium hydroxide or calcium hydroxide) or an alkali metal salt of a
carboxylate organic compound (e.g., an alkali metal salt of
citrate, such as di-sodium citrate).
Composite-Release Promoter
[0216] The composite-release promoter acts to facilitate release of
the wood composite from the press apparatus used to make the
composite. In the absence of a composite-release promoter, certain
composites may stick to the press apparatus, making it difficult to
separate the composite from the press apparatus. The
composite-release promoter solves this problem by facilitating
release of the wood composite. Exemplary composite-release
promoters include silicones (e.g., silicones described above),
fatty acids, a salt of a fatty acid, waxes, and amide compounds.
Exemplary fatty acids or salts thereof include a C.sub.10-25
alkanoic acid, a salt of a C.sub.10-25 alkanoic acid, a C.sub.10-25
alkenoic acid, a salt of an C.sub.10-25 alkenoic acid; e.g.,
stearic acid, zinc stearate, lauric acid, oleic acid or a salt
thereof (such as an alkali metal salt of oleic acid, such as
potassium oleate). It is understood that a mixture of two or more
of the aforementioned exemplary composite-release promoters can
also be used in the adhesive compositions herein. An exemplary
amide compound is N,N'-ethylenebisstearamide. Exemplary waxes
include those described above for the agent that improves moisture
resistance, and in particular, Hexion EW-58H; E Square 165 Amber
Petroleum Microcrystalline Wax commercially available from Baker
Hughes, Inc.; and Masurf FS 115 Emulsion (28% Solids) commercially
available from Mason Chemical Company. One additional advantage of
the protein component in the adhesive composition is that it can
facilitate dispersion of the composite-release promoter--this
feature allows less composite-release promoter to be used in the
adhesive composition and final composite product. Reducing the
amount of composite-release promoter is advantageous for agents
that are relatively more expensive, such as certain silicone
composite-release promoters.
[0217] In certain embodiments, the composite-release promoter is a
silicone.
[0218] Further, in certain embodiments, a composite-release
promoter is present in the final composite at a weight percent in
the range of about 0.01% (w/w) to about 5% (w/w), about 0.01% (w/w)
to about 2% (w/w), or about 0.01% (w/w) to about 1% (w/w).
Formaldehyde Scavenging Agent
[0219] A variety of formaldehyde scavenging agents are described in
the literature and are contemplated to be amenable to the present
invention. Different formaldehyde scavenging agents have different
reactivity profiles, and a particular formaldehyde scavenging agent
(e.g., H.sub.2NC(O)NH.sub.2, Me.sub.2NC(O)NH.sub.2, or
CH.sub.3CH.sub.2NH.sub.2) can be selected to optimize the
performance properties of the adhesive composition and/or binder
composition formed by the adhesive. Accordingly, in certain
embodiments, the formaldehyde scavenging agent has the formula
RNH.sub.2, R.sub.2NH, RC(O)NH.sub.2, RN(H)C(O)NH.sub.2,
R.sub.2NC(O)NH.sub.2, or RN(H)C(O)N(H)R, wherein R represents
independently for each occurrence H, alkyl, aryl, or aralkyl. In
certain embodiments, the formaldehyde scavenging agent has the
formula RN(H)C(O)N(H)R, wherein R represents independently for each
occurrence H, alkyl, aryl, or aralkyl. In certain other
embodiments, the formaldehyde scavenging agent is
H.sub.2NC(O)NH.sub.2, H.sub.2NC(O)N(H)Me, MeN(H)C(O)N(H)Me,
H.sub.2NC(O)N(CH.sub.3).sub.2, CH.sub.3C(O)NH.sub.2,
CH.sub.3CH.sub.2C(O)NH.sub.2, CH.sub.3NH.sub.2,
CH.sub.3CH.sub.2NH.sub.2, (CH.sub.3).sub.2NH, or
(CH.sub.3CH.sub.2).sub.2NH. In still other embodiments, the
formaldehyde scavenging agent is H.sub.2NC(O)NH.sub.2.
[0220] The term "alkyl" as used herein refers to a saturated
straight or branched hydrocarbon, such as a straight or branched
group of 1-12, 1-10, or 1-6 carbon atoms, referred to herein as
C.sub.1-C.sub.12alkyl, C.sub.1-C.sub.10alkyl, and
C.sub.1-C.sub.6alkyl, respectively. Exemplary alkyl groups include,
but are not limited to, methyl, ethyl, propyl, isopropyl,
2-methyl-1-propyl, 2-methyl-2-propyl, 2-methyl-1-butyl,
3-methyl-1-butyl, 2-methyl-3-butyl, 2,2-dimethyl-1-propyl,
2-methyl-1-pentyl, 3-methyl-1-pentyl, 4-methyl-1-pentyl,
2-methyl-2-pentyl, 3-methyl-2-pentyl, 4-methyl-2-pentyl,
2,2-dimethyl-1-butyl, 3,3-dimethyl-1-butyl, 2-ethyl-1-butyl, butyl,
isobutyl, t-butyl, pentyl, isopentyl, neopentyl, hexyl, heptyl,
octyl, etc.
[0221] The term "aryl" as used herein refers to refers to a mono-,
bi-, or other multi-carbocyclic, aromatic ring system. Unless
specified otherwise, the aromatic ring is optionally substituted at
one or more ring positions with substituents selected from
alkanoyl, alkoxy, alkyl, alkenyl, alkynyl, amido, amidino, amino,
aryl, arylalkyl, azido, carbamate, carbonate, carboxy, cyano,
cycloalkyl, ester, ether, formyl, halogen, haloalkyl, heteroaryl,
heterocyclyl, hydroxyl, imino, ketone, nitro, phosphate,
phosphonato, phosphinato, sulfate, sulfide, sulfonamido, sulfonyl
and thiocarbonyl. The term "aryl" also includes polycyclic ring
systems having two or more cyclic rings in which two or more
carbons are common to two adjoining rings (the rings are "fused
rings") wherein at least one of the rings is aromatic, e.g., the
other cyclic rings may be cycloalkyls, cycloalkenyls,
cycloalkynyls, and/or aryls. Exemplary aryl groups include, but are
not limited to, phenyl, tolyl, anthracenyl, fluorenyl, indenyl,
azulenyl, and naphthyl, as well as benzo-fused carbocyclic moieties
such as 5,6,7,8-tetrahydronaphthyl. In certain embodiments, the
aryl group is not substituted, i.e., it is unsubstituted.
[0222] The term "aralkyl" as used herein refers to an aryl group
having at least one alkyl substituent, e.g. aryl-alkyl-. Exemplary
aralkyl groups include, but are not limited to, arylalkyls having a
monocyclic aromatic ring system, wherein the ring comprises 6
carbon atoms. For example, "phenylalkyl" includes
phenylC.sub.4alkyl, benzyl, 1-phenylethyl, 2-phenylethyl, etc.
[0223] The amount of formaldehyde scavenging agent in the adhesive
formulation can adjusted to optimize the performance properties of
the adhesive composition and/or binder composition formed by the
adhesive. In certain embodiments, the mole ratio of formaldehyde
scavenging agent to reactive prepolymer is at least about 0.1:1, at
least about 0.5:1, at least about 1:1, at least about 2:1, at least
about 3:1, at least about 4:1 or at least about 5:1. In certain
embodiments, the mole ratio of formaldehyde scavenging agent to
reactive prepolymer is in the range of from about 0.01: to about
0.5:1, from about 0.5:1 to about 5:1, or from about 1:1 to about
4:1. In still other embodiments, the mole ratio of formaldehyde
scavenging agent to reactive prepolymer is at least 0.05:1. In
still other embodiments, the mole ratio of formaldehyde scavenging
agent to reactive prepolymer is at least 5:1.
[0224] In certain embodiments, the formaldehyde scavenging agent is
present in an amount from about 1% to about 50% (w/w), from about
1% to about 30% (w/w), from about 1% to about 20% (w/w), from about
5% to about 50% (w/w), from about 5% to about 30% (w/w), from about
5% to about 20% (w/w), from about 10% to about 50% (w/w), from
about 10% to about 30% (w/w), or from about 10% to about 20% (w/w)
of the adhesive composition. In certain other embodiments, the
formaldehyde scavenging agent is present in an amount from about 1%
to about 50% (w/w) of the adhesive composition. In still other
embodiments, the formaldehyde scavenging agent is present in an
amount from about 2% to about 30% (w/w) of the adhesive
composition.
Fire Retardants
[0225] Exemplary fire retardants include, for example, (i)
phosphoric acid or a salt thereof, such as a mono-ammonium
phosphate, di-ammonium phosphate, ammonium poly-phosphate, melamine
phosphate, guanidine phosphate, urea phosphate, alkali metal
phosphate, and alkaline earth metal phosphate, (ii) a halogenated
phosphate compound, (iii) a phosphate ester, such as tri-o-cresyl
phosphate and tris(2,3-dibromopropyl)phosphate, (iv) a chlorinated
organic compound, such as a chlorinated hydrocarbon or chlorinated
paraffin, (iv) a brominated organic compound, such as a brominated
hydrocarbon, bromo-bisphenol A, tetrabromobisphenol A (TBBPA),
decabromobiphenyl ether, octabromobiphenyl ether,
tetrabromobiphenyl ether, hexabromocyclododecane,
bis(tetrabromophthalimido) ethane, tribromophenol, and
bis(tribromophenoxy) ethane, (v) a brominated oligomer or
brominated polymer, such as TBBPA polycarbonate oligomer,
brominated polystyrene, and TBBPA epoxy oligomer, (vi) a borate
compound, such as an alkali metal borate, ammonium borate, or
mixture comprising one or more of borax, boric acid, boric oxide,
and disodium octoborate, (vii) aluminium materials, such as
aluminium trihydrate and aluminium hydroxide, (viii) an alkaline
earth metal hydroxide, such as magnesium hydroxide, (ix) an alkali
metal bicarbonate, such as sodium bicarbonate, (x) an alkaline
earth metal carbonate, such as calcium carbonate, (xi) antimony
trioxide, (xii) hydrated silica, (xiii) hydrated alumina, (xiv)
dicyandiamide, (xv) ammonium sulfate, and (xvi) a mixture of
guanylurea phosphate and boric acid, such as those described in
International Patent Application Publication No. WO 02/070215,
which is hereby incorporated by reference, (xvii) graphite, (xviii)
melamine, and (xix) a phosphonate compound, such as
diethyl-N,N-bis(2-hydroxyethyl)aminoethyl phosphonate;
dimethyl-N,N-bis(2-hydroxyethyl)aminomethyl phosphonate;
dipropyl-N,N-bis(3-hydroxypropyl)aminoethyl phosphonate; and
dimethyl-N,N-bis(4-hydroxybutyl)aminomethyl phosphonate, such as
described in U.S. Pat. No. 6,713,168, which is hereby incorporated
by reference.
[0226] In certain embodiments, the fire retardant is (i) phosphoric
acid or a salt thereof, such as a mono-ammonium phosphate,
di-ammonium phosphate, ammonium poly-phosphate, melamine phosphate,
guanidine phosphate, urea phosphate, alkali metal phosphate, and
alkaline earth metal phosphate, (ii) a phosphate ester, such as
tri-o-cresyl phosphate and tris(2,3-dibromopropyl)phosphate,
aluminium trihydrate and aluminium hydroxide, (iii) an alkaline
earth metal hydroxide, such as magnesium hydroxide, (iv) an alkali
metal bicarbonate, such as sodium bicarbonate, (v) antimony
trioxide, or (vi) hydrated alumina.
[0227] In certain other embodiments, the fire retardant is
Colemanite (CaB.sub.3O.sub.4(OH).sub.3--H.sub.2O).
Wood Preservatives
[0228] Exemplary wood preservatives include, for example, (i)
chromated copper arsenate (CCA), (ii) alkaline copper quaternary,
(iii) copper azole, (iv) a borate preservative compound, (v) a
sodium silicate-based preservative compound, (vi) a potassium
silicate-based preservative compound, (vii) a bifenthrin
preservative compound, (viii) a coal-tar creosote, (ix) linseed
oil, (x) tung oil, and (xi) an insecticide, such as an
organochloride compound, organophosphate compound, carbamate
compound, pyrethroid, neonicotinoid, and ryanoid.
V. Adhesive Compositions
[0229] It is understood that a variety of adhesives can be prepared
using the methods and compositions described herein. The adhesives
can be one-part adhesives or two-part adhesives, as shown in FIG.
1.
[0230] A. One-Part Adhesives
[0231] The invention provides a variety of stand alone or one-part
adhesives, as shown in FIG. 1. The one-part adhesives can be
produced using the protein components, reactive prepolymers and
additives discussed hereinabove. In their simplest form, the
one-part adhesives do not require any additional components to cure
and form an adhesive material.
[0232] In one embodiment, the invention provides an adhesive
composition comprising: (a) from about 1% to about 90% (w/w) of a
reactive prepolymer; (b) ground plant meal in an amount sufficient
to disperse the reaction prepolymer in an aqueous medium, and (c)
at least one first additive selected from the group consisting of a
partially exfoliated clay, an exfoliated clay, an intercalated
clay, cellulose nanoparticles, and a mixture of a silicone and a
terpene compound. In certain embodiments, the adhesive composition
further comprises a fire retardant and/or a wood preservative.
[0233] In another embodiment, the invention provides an adhesive
composition comprising: (a) from about 1% to about 90% (w/w) of a
reactive prepolymer; (b) from about 10% to about 98% (w/w) of an
isolated polypeptide composition capable of dispersing the reactive
prepolymer in an aqueous medium; and (c) at least one first
additive selected from the group consisting of a partially
exfoliated clay, an exfoliated clay, an intercalated clay,
cellulose nanoparticles, and a mixture of a silicone and a terpene
compound. In certain embodiments, the adhesive composition
comprises from about 5% to about 90% (w/w) of a reactive
prepolymer. In certain other embodiments, the adhesive composition
contains 10% to 99.9% (w/w), or 10% to 98% (w/w), of the protein
component (i.e., ground plant meal or isolated polypeptide
composition), and is free of reactive isocyanate compounds. Such
compositions optionally further comprise one or more second
additives, e.g., a water-soluble polymer, water-dispersible latex
polymer, organosilane, other water-soluble or water-dispersible
material, fire retardant, or wood preservative.
[0234] In another embodiment, the invention provides an adhesive
composition comprising (a) from about 1% to about 90% (w/w) of a
reactive prepolymer; (b) ground plant meal in an amount sufficient
to disperse the reactive prepolymer in an aqueous medium; and (c)
at least one first additive selected from the group consisting of a
fire retardant and wood preservative. In certain embodiments, the
adhesive composition further comprises a second additive (e.g., a
partially exfoliated clay, an exfoliated clay, or an intercalated
clay).
[0235] In another embodiment, the invention provides an adhesive
composition comprising (a) from about 1% to about 90% (w/w) of a
reactive prepolymer; (b) from about 10% to about 98% (w/w) of an
isolated polypeptide composition capable of dispersing the reactive
prepolymer in an aqueous medium; and (c) at least one first
additive selected from the group consisting of a fire retardant and
wood preservative. In certain embodiments, the adhesive composition
further comprises a second additive (e.g., a partially exfoliated
clay, an exfoliated clay, or an intercalated clay).
[0236] In certain embodiments, isocyanate reactive component
formulations are one-part adhesives. The one-part adhesives
desirably are a liquid at 25.degree. C. and stable to storage for
at least one week (7 days) at 25.degree. C., at least two weeks at
25.degree. C., at least one month at 25.degree. C., or at least
three months at 25.degree. C.
[0237] The adhesives can be cured by allowing the adhesive to stand
under ambient conditions, or the adhesive may be cured by exposing
the adhesive to heat, pressure, or both. Furthermore, in certain
embodiments, these adhesives are stable but can cure when exposed
to the moisture in air.
[0238] In certain embodiments, the one-part adhesive composition
comprises no less than about 2%, 5%, 10%, 15%, 20%, 25%, or 30% by
weight of the protein component (i.e., ground plant meal or
isolated polypeptide composition) described herein (based on the
dry weight of the protein component), relative to the total
polyisocyanate composition weight. The maximum loading of the
protein component can be based on the amount of free isocyanate
(--NCO) groups in the final composition, as well as optimizing
stability and viscosity sufficiently. In certain embodiments, the
total concentration of protein component may be of up to 35%
(wt/wt). Higher viscosity compositions formed from higher weight
percentages of the protein component described herein can be
beneficial in applications where it is desirable for the uncured
adhesive to exhibit cold-tack, flow resistance, sag resistance, and
gap-filling characteristics.
[0239] A more specific embodiment relates to an adhesive
composition comprising: (a) from about 10% to about 30% (w/w) of a
reactive prepolymer; (b) from about 10% to about 30% (w/w) ground
plant meal; (c) from about 0.1% to about 6% (w/w) of at least one
first additive selected from the group consisting of a partially
exfoliated clay, an exfoliated clay, an intercalated clay,
cellulose nanoparticles, and a mixture of a silicone and a terpene
compound; and (d) from about 30% to about 70% (w/w) water. In
certain embodiments, the reactive prepolymer is polymeric
diphenylmethane diisocyanate. In certain embodiments, the ground
plant meal is ground canola meal. In certain embodiments, the at
least one first additive is an intercalated clay, such as
montmorillonite intercalated with a
dimethyl-di(C.sub.14-C.sub.18)alkyl ammonium salt. In certain
embodiments, the at least one first additive is montmorillonite
intercalated with a dimethyl-di(C.sub.14-C.sub.18)alkyl ammonium
salt, wherein such compound is present in an amount ranging from
0.5% to about 3% (w/w) of the adhesive composition. In certain
embodiments, the adhesive composition further comprises silicone
and limonene, such as where the silicone and limonene together
constitute from about 1% to about 10% (w/w) of the adhesive
composition. In certain embodiments, the weight percent ratio of
silicone to limonene is in the range of 1:2 to 2:1. In certain
embodiments, the adhesive composition further comprises urea, such
as where the urea is present in an amount ranging from about 0.5%
to about 5% (w/w) of the adhesive composition.
[0240] Another more specific embodiment relates to an adhesive
composition comprising: (a) from about 5% to about 40% (w/w) of a
reactive prepolymer; (b) from about 5% to about 30% (w/w) ground
plant meal; (c) from about 1% to about 40% (w/w) of a dry powder
fire retardant; and (d) from about 30% to about 70% (w/w) water. In
certain embodiments, the reactive prepolymer is polymeric
diphenylmethane diisocyanate. In certain embodiments, the ground
plant meal is ground canola meal. In certain embodiments, the dry
powder fire retardant is present in an amount ranging from 20% to
about 35% (w/w) of the adhesive composition. In certain
embodiments, the dry powder fire retardant is colemanite. In
certain embodiments, the dry powder fire retardant is colemanite in
an amount ranging from 20% to about 35% (w/w) of the adhesive
composition.
[0241] B. Two- or Multi-Part Adhesives
[0242] In addition, the invention provides a variety of two- or
multi-part adhesives as shown in FIG. 1. The two-part adhesives can
be formed using the protein component (i.e., ground plant meal or
isolated polypeptide composition), prepolymers and additives
discussed above.
[0243] The two-part adhesives require mixing two or more stable
materials (mixtures) that upon mixing together produce an adhesive
material. Such compositions are generally used within a short time
period after mixing because the components may begin to react upon
mixing. In one embodiment, the invention provides a two-part
adhesive composition comprising: (a) a first part (Part A)
comprising from about 0.1% to about 100% (w/w) of a reactive
prepolymer, wherein the reactive prepolymer is a
polyisocyanate-based prepolymer, an epoxy-based prepolymer, or a
combination thereof; (b) a second part (Part B) comprising from
about 10% to about 99% (w/w) of an isolated polypeptide composition
capable of dispersing the reactive prepolymer in an aqueous medium,
and at least one first additive selected from the group consisting
of a partially exfoliated clay, an exfoliated clay, an intercalated
clay, cellulose nanoparticles, and a mixture of a silicone and a
terpene compound. In certain other embodiments, the two-part
adhesive comprises a first part (Part A) comprising from about 1%
to about 10% (w/w) of a reactive prepolymer, from about 5% to about
50% (w/w) of a reactive prepolymer, from about 5% to about 90%
(w/w) of a reactive prepolymer, from about 75% to about 100% (w/w)
of a reactive prepolymer, or from about 95% to about 100% (w/w) of
a reactive prepolymer.
[0244] In another embodiment, the invention provides a two-part
adhesive composition comprising: (a) a first part (Part A)
comprising from about 0.1% to about 100% (w/w) of a reactive
prepolymer, wherein the reactive prepolymer is a
polyisocyanate-based prepolymer, an epoxy-based prepolymer, or a
combination thereof; (b) a second part (Part B) comprising (i) from
about 10% to about 99% (w/w) of a ground plant meal capable of
dispersing the reactive prepolymer in an aqueous medium, and (ii)
at least one first additive selected from the group consisting of a
partially exfoliated clay, an exfoliated clay, an intercalated
clay, cellulose nanoparticles, and a mixture of a silicone and a
terpene compound. In another embodiment, the invention provides a
two-part adhesive composition comprising: (a) a first part (Part A)
comprising from about 5% to about 90% (w/w) of a reactive
prepolymer, wherein the reactive prepolymer is a
polyisocyanate-based prepolymer, an epoxy-based prepolymer, or a
combination thereof; (b) a second part (Part B) comprising (i) from
about 10% to about 99% (w/w) of a ground plant meal capable of
dispersing the reactive prepolymer in an aqueous medium, and (ii)
at least one first additive selected from the group consisting of a
partially exfoliated clay, an exfoliated clay, an intercalated
clay, cellulose nanoparticles, and a mixture of a silicone and a
terpene compound. In certain other embodiments, the two-part
adhesive comprises a first part (Part A) comprising from about 1%
to about 10% (w/w) of a reactive prepolymer, from about 5% to about
50% (w/w) of a reactive prepolymer, from about 5% to about 90%
(w/w) of a reactive prepolymer, from about 75% to about 100% (w/w)
of a reactive prepolymer, or from about 95% to about 100% (w/w) of
a reactive prepolymer.
[0245] In another embodiment, the invention provides a two-part
adhesive composition comprising (a) a first part (Part A)
comprising from about 5% to about 90% (w/w) of a reactive
prepolymer, wherein the reactive prepolymer is a
polyisocyanate-based prepolymer, an epoxy-based prepolymer, or a
combination thereof; (b) a second part (Part B) comprising from
about 10% to about 99% (w/w) of an isolated polypeptide composition
capable of dispersing the reactive prepolymer in an aqueous medium;
and (c) at least one first additive selected from the group
consisting of a fire retardant and wood preservative, which may be
in Part A, Part B, or both Part A and Part B. In certain
embodiments, the adhesive composition further comprises a second
additive (e.g., a partially exfoliated clay, an exfoliated clay, or
an intercalated clay).
[0246] Depending upon the composition of Part A and Part B, Parts A
and B are mixed immediately prior to use. In one embodiment, the
adhesive, when cured, comprises from about 1% to about 95% (w/w) of
non-volatile moieties of Part A and from about 5% to about 99%
(w/w) of non-volatile moieties of Part B. In certain embodiments,
Part A comprises PMDI together with a catalyst. In certain other
embodiments, part of the diphenylmethane 4,4'-diisocyanate, known
as MMDI, present in the PMDI is recovered by means of a suitable
technological operation such as distillation or
crystallization.
[0247] The qualitative impact of the relative level of the isolated
polypeptide composition (or ground plant meal) on the performance
characteristics of a two-part adhesive like those described herein
is set forth in FIG. 3. It is understood that the amount of
isolated polypeptide composition (and the type of isolated
polypeptide composition) or ground plant meal can be adjusted to
optimize properties of the adhesive composition, e.g., viscosity,
bond-strength, gap-filing capability, pot life, moisture
resistance, and cost. To illustrate, adhesive compositions formed
from certain whey protein derivatives have a short pot life,
whereas adhesive compositions formed from certain castor protein
have a longer pot life. To optimize the viscosity of the adhesive
composition, the skilled artisan can adjusted the amount of solid
protein in the adhesive composition. For example, higher levels of
solid protein in the adhesive composition can provide an adhesive
composition having a higher viscosity. Such higher viscosity
adhesive compositions can be used for gap filing applications. To
optimize the moisture resistance of the adhesive, the skilled
artisan can adjust the amount of water-insoluble/water-dispersible
protein relative to the amount of water-soluble protein used to
form the adhesive composition. In certain instances, the adhesive
compositions contain a larger percentage by weight of the
water-insoluble/water-dispersible protein than the amount of
water-soluble protein.
[0248] Various components of the activatable multi-part adhesive
systems can include, for example, a polypeptide containing
compound; and an isocyanate reactive composition as a separate
component. The isocyanate reactive component can optionally
comprise a protein that contains residual peptide linkages.
[0249] In certain embodiments, the multi-part system further
comprises either an ethylene copolymer resin, a hydroxyl
functionalized polymer, or mixtures thereof. Non limiting examples
of suitable ethylene copolymer resins include ethylene vinyl
acetate (EVA), ethylene-co-vinylacetate-co-acrylic acid,
ethylene-co-vinylacetate-co-methacrylic acid,
ethylene-co-vinylacetate-co-vinylalcohol, carboxylated vinyl
acetate-ethylene copolymers, and ethylene vinyl alcohol (EVOH)
resins. Non-limiting examples of hydroxyl functionalized polymers
include water soluble or partially water soluble polymers such as
polyvinylalcohol, polyvinylbutyral-co-vinylalcohol,
polyvinylacetate-co-vinylalcohol and the like; and carbohydrates
such as carboxymethylcellulose, ethylmethylcellulose, etc.
[0250] The ethylene copolymer can be used as a water dispersion
agent (i.e., an EVA latex). The dispersion agent can be a polymer
latex containing a carboxylated vinyl acetate-ethylene terpolymer
stabilized with poly-(vinyl alcohol), commercially known as AIRFLEX
426.RTM. from Air Products, Inc. (63% solids by weight). In certain
other embodiments, the dispersion agent is Wacker VINNAPAS.RTM.
426, which is a carboxylated, high solids vinyl acetate-ethylene
(VAE) copolymer dispersion with a glass transition temperature (Tg)
of 0.degree. C., sold by Wacker Chemie, AG. The ethylene copolymer
can be used at a level of from 5% to 50% by weight, from 10% to 40%
by weight, or from 15% or 30% by weight of the total isocyanate
reactive component (the level of ethylene copolymer is expressed on
a solids basis, and does not include the level of water in the
latex). Additional latex polymers that may be used include, for
example, acrylic homopolymers (e.g., poly(methylmethacrylate) and
poly(isobutylmethacrylate)) and acrylic copolymers (e.g.,
poly(isobutylmethacrylate-co-methylacrylate) and
poly(ethylene-co-methylmethacrylate)).
[0251] It is understood that the isocyanate reactive compositions
(Part-B) of a two-part adhesive kit can contain other optional
ingredients, including hydroxy-functional compounds (examples
including amine-functional compounds, e.g., polyols such as
polyethylene glycol, glycerin, polypropylene glycol, carbohydrates,
starches, polyvinyl alcohol and copolymers thereof,
trimethylolpropane, branched polyols such as trimethylolpropane
ethoxylate, aromatic alcohols or polyols, pentaerythritol and its
polyol adducts, etc.). These types of optional hydroxy-functional
compounds can either be blended together with the proteins and the
other ingredients during the preparation of the Part-B component,
or they can be optionally added to the proteins themselves during
or after any of the process steps that are used to prepare and
isolate the proteins (e.g., during protein isolation or extraction
from meal, during digestion, during derivatization, etc; or after
spray drying, after freeze drying, after isolation of a water-based
paste of water-insoluble/water-dispersible protein, etc.). When the
optional hydroxyl-functional compounds are used in this way, the
preferred range of addition spans from about 0.1% to 10% by weight
of the protein, and more preferably, from about 0.5% to 2% by
weight of the protein.
[0252] In certain embodiments, the isocyanate reactive composition
further comprises water. In certain embodiments, water is present
in an amount from about 10% (w/w) to about 60% (w/w), from about
10% (w/w) to about 50% (w/w), from about 10% (w/w) to about 40%
(w/w), from about 20% (w/w) to about 60% (w/w), from about 20%
(w/w) to about 50% (w/w), from about 20% (w/w) to about 40% (w/w),
from about 30% to about 75% (w/w), from about 30% (w/w) to about
60% (w/w), from about 30% (w/w) to about 50% (w/w), from about 30%
(w/w) to about 40% (w/w), from about 40% to about 70% (w/w), from
about 50% to about 60% (w/w), from about 5% (w/w) to about 85%
(w/w), or from about 15% (w/w) to about 35% (w/w) of the adhesive
composition. In still other embodiments, water is present in an
amount from about 25% (w/w) to about 55% (w/w), from about 35%
(w/w) to about 55% (w/w), or from about 45% (w/w) to about 55%
(w/w) of the adhesive composition. In still other embodiments,
water is present in an amount from about 30% (w/w) to about 60%
(w/w) of the adhesive composition. In certain embodiments, the
adhesive composition has a pH in the range of from about 4 to about
9, from about 5 to about 8, or about 6 to about 8.
[0253] In certain other embodiments, the isocyanate reactive
composition further comprises from about 1% to 30% (wt/wt), about
10 to 30% (wt/wt), about 10% to 20% (wt/wt), about 1% to 10%
(wt/wt), or about 3% to 10% (wt/wt) polyol.
[0254] In embodiments where the isocyanate reactive composition
comprises at least 20% (wt/wt), 25%, or 27% (wt/wt) isolated
polypeptide composition. The polypeptides in the isolated
polypeptide composition can be an enzyme digested native protein,
derivatized enzyme digested protein, or mixture thereof. In certain
embodiments, the isocyanate reactive composition comprises
derivatized enzyme digested protein. In certain embodiments, the
derivatized enzyme digested protein is at least 50% (wt/wt), 60%
(wt/wt), or 70% (wt/wt) of the isolated polypeptide composition
contained in the isocyanate reactive composition. In certain
embodiments, the polypeptides contained in the isocyanate reactive
composition are obtained from the same native protein source, or
from different native protein sources. In certain embodiments, the
isocyanate reactive composition remains a liquid and homogeneous
upon storage or processing.
[0255] In another embodiment, a multi-part is created by mixing two
or more liquid streams, which are stable by themselves, and convert
quickly into a cured polymer under relatively mild conditions
(relative to one-part adhesive systems). The two-part adhesives can
cure by standing at ambient conditions, or can be cured by exposure
to heat, pressure, or both.
[0256] It is understood that, for certain applications, the
adhesive compositions, in addition to containing a water-insoluble
protein fraction can also include a water-soluble polypeptide
fraction. Depending upon the composition of the adhesive, the ratio
of the water-soluble polypeptide fraction to the water-insoluble
polypeptide fraction ranges from 0:1 to 3:2 (w/w). Alternatively,
the weight ratio of the water-insoluble polypeptide fraction to the
water-soluble polypeptide fraction can be at least 1:1. More
particularly, when the protein fractions are obtained by washing
plant meal with water to separate a water-insoluble protein
fraction and a water-soluble protein fraction, then the ratio of
the water-soluble protein fraction to water-insoluble protein
fraction can be in the range of from 0:1 to 3:2 (w/w).
Alternatively, when the protein fractions are obtained by washing
plant meal with water to separate a water-insoluble protein
fraction and a water-soluble protein fraction, then the ratio of
the water-soluble protein fraction to water-insoluble protein
fraction can be at least 1:1 (w/w).
[0257] With regard to the two-part adhesives, the percent of solids
in Part B can range from about 5% to about 60%, from about 5% to
about 30%, from about 8% to about 20%, or from about 10% to about
20% by weight of solids. Furthermore, depending upon the
application, the weight ratio of solids in Part B to the prepolymer
can range from 100:0.1 to 0.1:100, from 50:1 to 1:50, from 20:1 to
about 1:20 or from 10:1 to about 1:10.
General Considerations
[0258] It is understood that varying the reaction between the
protein component (i.e., ground plant meal or isolated polypeptide
composition) and the reactive prepolymers can be done to optimize
stability, shelf life, viscosity, and bonding performance that is
necessary for the final application.
[0259] In certain embodiments, the viscosity of all the types of
polyisocyanate compositions as described herein, is no more than
(NMT) 500,000 cps, NMT 300,000 cps, NMT 200,000 cps, or NMT 100,000
cps, NMR 50,000 cps, NMT 25,000 cps, NMT 10,000 cps, or NMT 5,000
cps as measured at 25.degree. C. until the polyisocyanate
composition is cured.
[0260] Furthermore, the viscosity of the adhesive can be designed
with a particular application in mind. In one embodiment, where gap
filling adhesives are required, the minimum viscosity of the
adhesive (polyisocyanate composition) should be no less than (NLT)
2000 cps, 3000 cps, or NLT 4000 cps, as measured at 25.degree. C.
The viscosity of the polyisocyanate compositions can be optimized
by adjusting the amount of protein component (i.e., ground plant
meal or isolated polypeptide composition) described herein and/or
the conditions used for preparing the composition. Typical
conditions are in the range from 25 to 100.degree. C. at ambient
pressure, with agitation of the mixture until a sufficiently
homogeneous composition is achieved.
[0261] In order to optimize the viscosity of the adhesive
composition, the adhesive composition may contain ground plant meal
in an amount such that the viscosity of the adhesive formulation
increases by no more than about 25% within about 20 minutes, or no
more than about 50% within about 20 minutes, after mixing the
prepolymer and ground plant meal with a nucleophile. In certain
other embodiments, the ground plant meal is present in an amount
such that the viscosity of the adhesive formulation increases by no
more than about 40% within about 30 minutes (or no more than about
40% with about 100 minutes) after mixing the prepolymer and ground
plant meal with a nucleophile. In certain other embodiments, the
ground plant meal is present in an amount such that the viscosity
of the adhesive formulation remains less than about 1100 cps within
about 150 minutes after mixing, less than about 1100 cps within
about 200 minutes after mixing, less than about 1500 cps within
about 150 minutes after mixing, less than about 1500 cps within
about 225 minutes after mixing, less than about 50,000 cps within
about 150 minutes after mixing, less than about 50,000 cps within
about 20 minutes after mixing, less than about 30,000 cps within
about 20 minutes after mixing, less than about 300,000 cps within
about 60 minutes after mixing, or less than about 100,000 cps
within about 60 minutes after mixing the prepolymer and ground
plant meal with a nucleophile.
[0262] Certain of the adhesives described herein are liquids having
viscosities low enough to render them pourable, sprayable, or
curtain-coatable. For pourable or sprayable adhesive compositions,
the viscosity of the adhesive composition is desirably no more than
(NMT) 500 cps, NMT 1000 cps, NMT 2000 cps, or NMT 5000 cps, as
measured at 25.degree. C. The viscosity of the adhesive composition
can be optimized by adjusting the amount of protein component
(i.e., ground plant meal or isolated polypeptide composition)
described herein and/or the conditions used for preparing the
composition. Alternatively, certain of the adhesives described
herein are non-pourable, extrudable, spreadable gels or pastes.
Non-pourable, extrudable, spreadable gels, or pastes may become
pourable, sprayable, or curtain-coatable liquids at elevated
temperature, and may optionally revert to non-pourable, extrudable
or spreadable gels or pastes upon cooling.
[0263] The adhesive composition can be also characterized according
to the weight percent of the ground plant meal in the composition.
In certain embodiments, the ground plant meal is present in an
amount from about 1% to about 90% (w/w), from about 1% to about 70%
(w/w), from about 1% to about 50% (w/w), from about 1% to about 30%
(w/w), from about 10% to about 90% (w/w), from about 10% to about
70% (w/w), from about 10% to about 50% (w/w), from about 10% to
about 30% (w/w), from about 20% to about 90% (w/w), from about 20%
to about 70% (w/w), from about 20% to about 50% (w/w), or from
about 20% to about 30% (w/w) of the adhesive composition. In
certain other embodiments, the ground plant meal is present in an
amount from about 5% to about 35% (w/w), or from about 5% to about
50% (w/w), of the adhesive composition. In still other embodiments,
the ground plant meal is present in an amount from about 15% to
about 25% (w/w) of the adhesive composition.
[0264] The adhesive composition can be also characterized according
to the weight percent of the reactive prepolymer in the
composition. In certain embodiments, the reactive prepolymer is
present in an amount from about 5% to about 50% (w/w), from about
5% to about 40% (w/w), from about 5% to about 30% (w/w), from about
5% to about 25% (w/w), from about 5% to about 20% (w/w), from about
5% to about 15% (w/w), from about 10% to about 50% (w/w), from
about 10% to about 40% (w/w), from about 10% to about 30% (w/w),
from about 10% to about 25% (w/w), from about 10% to about 20%
(w/w), from about 10% to about 15% (w/w), from about 15% to about
50% (w/w), from about 15% to about 40% (w/w), from about 15% to
about 30% (w/w), from about 15% to about 25% (w/w), from about 15%
to about 20% (w/w), from about 20% to about 50% (w/w), from about
20% to about 40% (w/w), from about 20% to about 30% (w/w), or from
about 20% to about 25% (w/w), of the adhesive composition. In
certain other embodiments, the reactive prepolymer is present in an
amount of from about 15% to about 25% (w/w) of the adhesive
composition. In yet other embodiments, the reactive prepolymer is
PMDI, and the PMDI is present in an amount of from about 15% to
about 25% (w/w) of the adhesive composition.
[0265] In certain other embodiments, the polypeptide containing
adhesives described herein are liquids, gels, or pastes stable
enough to be stored for at least one week, at least two weeks, at
least one month, or at least three months at ambient temperature
(25.degree. C.), and protected from moisture. The term "stable" in
connection with the viscosity of the polyisocyanate composition
refers to a viscosity that does not increase by more than 10%, 25%,
or 30%, from its initial value.
[0266] In addition, the isolated polypeptide composition and the
adhesive composition can be designed to have a polydispersity
index. The term "polydispersity index" refers to the ratio between
the weight average molecular weight and the number average
molecular weight (i.e., PDI=Mw/Mn).
[0267] The terms "number average molecular weight," denoted by the
symbol Mn and "weight average molecular weight," denoted by the
symbol Mw, are used in accordance with their conventional
definitions as can be found in the open literature. The weight
average molecular weight and number average molecular weight can be
determined using analytical procedures described in the art, e.g.,
chromatography techniques, sedimentation techniques, light
scattering techniques, solution viscosity techniques, functional
group analysis techniques, and mass spectroscopy techniques (e.g.,
MALDI mass spectroscopy). For instance, as illustrated in Example
2, average molecular weight and number average molecular weight of
the polypeptide composition was determined by MALDI mass
spectroscopy.
[0268] Further, it is contemplated that isolated polypeptide
compositions having different molecular weights may provide
adhesive compositions having different properties. As such, the
weight average molecular weight, number average molecular weight,
and polydispersity index can be an important indicator when
optimizing the features of the adhesive composition. In particular,
it is contemplated that the ability to optimize the molecular
weight characteristics of the isolated polypeptide compositions
provides advantages when preparing an adhesive composition for a
particular use. Further advantages include obtaining adhesive
compositions with similar properties even though the isolated
polypeptide composition may be obtained from a different source
(e.g., soy vs. castor) or when similar protein sources are
harvested during different seasons, over varying periods of time,
or from different parts of the world. For example, proteins
isolated from soy and castor (each having different molecular
weight distributions) can be made to have similar molecular weight
distributions through digestion and fractionation processes
described herein (see Example 2). Accordingly, the ability to
measure and control the consistency of molecular weight
distributions is contemplated to be beneficial when optimizing
various features of the adhesive composition, e.g., long-term
reproducibility of physical properties and process characteristics
of formulated adhesives. The molecular weight characteristics of
the ground plant meal or isolated polypeptide composition can be
altered by subjecting the proteins therein to enzymatic digestion
or fractionation according to the procedures described herein.
[0269] In certain embodiments, the PDI of the adhesives provided
herein is from about 1 to about 3, from 1 to 1.5, from 1.5 to 2,
from 2 to 2.5, from 2.5 to 3, from 1 to 2, from 1.5 to 2.5, or from
2 to 3.
[0270] Furthermore, a moisture-resistant adhesive can be prepared
by using the water-insoluble/water-dispersible extract alone, or
optionally including a plasticizer (for example, a water insoluble
plasticizer), an organosilane, and/or together with a lower-T.sub.g
polymer. The term "plasticizer" refers to any substance capable of
increasing the free volume (i.e., the molecular volume not occupied
by the polypeptide molecules or their bonds) of the
water-insoluble/water-dispersible extract. The term "Tg" refers to
the glass transition temperature of the polymer, i.e., the
temperature at which free volume of the polymer is large enough to
allow translational relaxation and self diffusion of the minimal
critical segment length of the polymer or molecule. In addition,
moisture resistance can be imparted by means of crosslinking using
a broad variety of crosslinking agents, for example, amine
compounds, organosilane compounds, epoxy compounds, or
epichlorhydrin-type materials. A moisture-resistant
pressure-sensitive adhesive can be prepared by using the
water-insoluble/water-dispersible extract blended in combination
with a plasticizer, optionally together with a low-T.sub.g polymer
or a high-Tg polymer.
[0271] Furthermore, the tack or bond strength of the pressure
sensitive adhesives (PSA) can be controlled through a number of
means, such as shifting the glass transition (T.sub.g) to higher or
lower temperatures (by controlling the levels of monomeric and/or
polymeric plasticizers) or incorporating flatting agents such as
silicas, glass spheres, clays, and the like; by adjusting the
crosslink density to higher or lower levels; by increasing or
decreasing the plasticizer concentration; by blending with higher
or lower molecular weight polymers; or by employing some
combination of these techniques.
[0272] It is understood that when evaluating the tack or bond
strength of a composite formed using an adhesive, the maximum
achievable strength of the composite is dictated by the cohesive
strength of the wood itself. To illustrate, if the adhesive is
cohesively stronger than the wood, then wood failure will be the
outcome. Further, it is contemplated that the adhesive composition
may be tailored to provide a bond strength appropriate for
particular applications by selecting particular polypeptide
fractions, prepolymers, catalysts, and/or other additives.
[0273] Depending upon the application, the resulting adhesives may
comprise from about 20% to about 80%, from about 30% to about 70%,
from about 40% to about 60% (w/w) of prepolymer in the total
adhesive (binder) composition.
[0274] Furthermore, depending upon the application, the resulting
cured article can comprise from about 0.05% to about 10%, from
about 0.05% to about 5.0%, from about 0.1% to about 4.0%, from
about 0.2% to about 3.0%, or from about 0.3% to about 2.0% (w/w) of
prepolymer. In certain embodiments, the cured article can comprise
from about 0.05% to about 2.5% (w/w) of prepolymer. In certain
other embodiments, the cured article can comprise from about 2.5%
to about 4% (w/w) of prepolymer.
[0275] Furthermore, an article fabricated from one or more of the
adhesives described herein can contain from about 1% to about 15%,
or from about 2% to about 10%, or from about 3% to about 8%, or
from about 4% to about 7%, or from about 3% to about 6% (w/w) of
binder (adhesive) per cured article. In certain embodiments, the
article fabricated from the adhesive may contain greater than 5%
(w/w) of binder per cured article. In certain other embodiments,
the article comprises from about 1.5% to about 2.5% of binder per
cured article.
[0276] Composite materials can contain from about 5% to about 85%
(w/w), about 15% to about 75% (w/w), about 30% to about 65% (w/w),
about 1% to about 10%, about 10% to about 20%, or about 20% to
about 70% (w/w) binder. Laminate materials can contain from about
0.1% to about 10% (w/w), about 0.5% to about 5%, about 1% to about
3% (w/w), about 1% to about 10%, about 20% to about 30%, or about
30% to about 70% (w/w) binder.
[0277] In certain embodiments, the adhesives described herein can
be used in the manufacture of particle board. With regard to the
preparation of moisture-resistant cured particle board composites,
the composites can comprise a total binder level ranging from about
1.5% to about 11% (w/w), or from about 2.5% to about 4.5% (w/w), of
the cured composite, wherein the binder includes a protein
component (i.e., ground plant meal or isolated polypeptide
composition) and a PMDI fraction with an optional catalyst. In
certain embodiments, the composites can comprise a total binder
level ranging from about 1.5% to about 20% (w/w) of the cured
composite, wherein the binder includes a protein component (i.e.,
ground plant meal or isolated polypeptide composition) and a PMDI
fraction with an optional catalyst. The amount of PMDI can range
from about 5% to about 30%, or from about 30% to about 70%, by
weight of the cured binder. The PMDI fraction can comprise from
about 0.8% to about 10% (w/w), from about 0.8% to about 4% (w/w),
or from about 1.3% to about 2.3% (w/w), of the cured composite. In
certain other embodiments, the adhesives described herein can be
used in the manufacture of medium density fiberboard (MDF), high
density fiberboard (HDF), or oriented strand board (OSB).
[0278] In another embodiment, a moisture resistant composite can be
prepared with a total binder level ranging from about 1.5% to about
11% (w/w), or from about 1.5% to about 2.5% (w/w), of the cured
composite, wherein the binder includes a protein component (i.e.,
ground plant meal or isolated polypeptide composition) and a PMDI
fraction with an optional catalyst. The PMDI fraction can comprise
from about 0.1% to about 10% (w/w), from about 0.1% to about 5%
(w/w), from about 0.2% to about 2.5% (w/w), or from about 0.3% to
about 1.4% (w/w) of the cured composite.
[0279] In another embodiment, a moisture-resistant cured particle
board composite can be prepared containing a total binder level
ranging from about 1.5% to about 15%, from about 1.5% to about 11%,
or from about 2.5% to about 3.1%, by weight of the cured composite,
wherein the binder comprises a protein component (i.e., ground
plant meal or isolated polypeptide composition), an optional
polymer latex fraction, and a PMDI fraction with optional catalyst.
The PMDI comprises from about 5% to about 65% by weight of the
cured binder and from about 0.1% to 10%, from about 0.1% to about
5%, from about 0.2% to about 2.5%, or from about 0.3% to about 2%
by weight of the cured composite. The optional polymer latex is an
EVA latex polymer comprising from about 0% to about 45% by weight
of the cured binder and from about 0% to about 1.2% by weight of
the cured composite. In certain other embodiments, a
moisture-resistant cured MDF composite, HDF composite, or OSB
composite can be prepared containing a total binder level ranging
from about 1.5% to about 15%, from about 1.5% to about 11%, or from
about 2.5% to about 3.1%, by weight of the cured composite, wherein
the binder comprises a protein component (i.e., ground plant meal
or isolated polypeptide composition), an optional polymer latex
fraction, and a PMDI fraction with optional catalyst.
[0280] In another embodiment, a moisture-resistant cured particle
board composite can be prepared with a total binder level ranging
from about 1.5% to about 15%, from about 1.5% to about 11%, or from
about 1.2% to about 2.5%, by weight of the cured composite. The
binder comprises a protein component (i.e., ground plant meal or
isolated polypeptide composition), an optional polymer latex
fraction, and a PMDI fraction with optional catalyst. The PMDI
fraction comprises from about 0.1% to about 10%, from about 1.5% to
about 5%, or from about 0.1% to about 1.1% by weight of the cured
composite. In certain other embodiments, a moisture-resistant cured
MDF composite, HDF composite, or OSB composite can be prepared with
a total binder level ranging from about 1.5% to about 15%, from
about 1.5% to about 11%, or from about 1.2% to about 2.5%, by
weight of the cured composite
[0281] In the event that moisture-resistance is not a requirement
for the end-use application, cured composites can also be prepared
with a total binder level of less than approximately 5% by weight
of the cured composite, wherein the binder comprises a protein
component (i.e., ground plant meal or isolated polypeptide
composition) and a PMDI fraction with an optional catalyst. The
PMDI fraction can comprise from about 0.05% to about 2.5% (w/w) of
the cured composite. Depending upon the level of water that can be
tolerated during the manufacture of the composite, binder levels of
greater than 5% can also be employed, wherein the PMDI fraction
comprises at least 0.05% by weight of the cured composite.
[0282] With regard to the two-part adhesives, the level of water
that can be used to disperse the ingredients and to fabricate a
composite can be adjusted for the specific application by virtue of
controlling the % solids in the Part-B component, the weight ratio
of the Part-B solids ingredients to PMDI, and the total binder
level in the finished composite (on a solids basis). Depending on
the level of water that is required to fabricate the composite, the
percent solids in the Part-B component will preferably range from
about 5% to 45% by weight solids, or more preferably from about 9%
to 30% by weight solids. Similarly, the Part-B solids to PMDI
weight ratio preferably ranges from approximately 20:1 to 1:20, and
more preferably from about 10:1 to 1:10. The total percentage of
binder in the cured composite (on a solids basis) preferably ranges
from approximately 1% to 15% by weight of the cured composite, and
more preferably from about 2% to 10% by weight.
[0283] Similar formulation considerations apply to the fabrication
and manufacture of plywood composites. For example,
moisture-resistant cured plywood assemblies can be laminated with
bondline adhesive levels ranging from approximately 0.008
pounds/ft..sup.2 up to approximately 0.056 pounds/ft..sup.2,
wherein the adhesive includes a protein component (i.e., ground
plant meal or isolated polypeptide composition), an optional
polymer latex fraction, and a PMDI fraction with an optional
catalyst. The PMDI can comprise from about 10% to about 80% (w/w),
or from about 20% to about 70% (w/w), of the cured adhesive. The
optional polymer latex can be an EVA polymer latex comprising
between about 0% and 45% of the cured binder. It is contemplated
that plywood composites prepared with these types of adhesive
compositions will be capable of withstanding boiling water and
hence will be extremely moisture resistant.
[0284] In the event that moisture-resistance is not a requirement
for the end-use application, cured plywood composites can also be
prepared with bondline adhesive levels of less than approximately
0.056 pounds/ft..sup.2, wherein the adhesive includes a protein
component (i.e., ground plant meal or isolated polypeptide
composition) and a PMDI fraction with an optional catalyst. The
PMDI fraction comprises less than approximately 20% by weight of
the cured adhesive.
[0285] The level of water that may be used to disperse the
ingredients and to fabricate a plywood composite can be adjusted
for the specific application by virtue of controlling the % solids
in the Part-B component, the weight ratio of the Part-B solids
ingredients to PMDI, and the total bondline application level in
the finished composite (on a solids basis). Depending on the level
of water that is required to fabricate the composite, the % solids
in the Part-B component will preferably range from approximately 5%
to 45% by weight solids, and more preferably from about 8% to 30%
by weight solids. Similarly, the Part-B solids to PMDI weight ratio
preferably ranges from approximately 20:1 to 1:20, and more
preferably from about 10:1 to 1:10.
[0286] In certain embodiments, both the one-part, the two-part and
the multi-part type adhesives are cold curable. In certain
embodiments, the adhesives include a cure catalyst (for example,
DMDEE in the case of adhesives containing a polyisocyanate) that
facilitates curing in the absence of applied heat. In certain
embodiments, the adhesives (for example, the polyisocyanate
containing adhesives) are cured in the presence of moisture at a
temperature of about 10.degree. C. to about the ambient temperature
range (25.degree. C., to as high as 30.degree. C.). In certain
other embodiments, the cold cure temperature ranges from 20.degree.
C. to 27.degree. C. In other embodiments, the adhesives are hot
cured, at temperatures greater than 30.degree. C. Hot curing may at
temperatures in the range from 50.degree. C. to 300.degree. C., or
from 90.degree. C. to 275.degree. C., or from 110.degree. C. to
250.degree. C.
[0287] The adhesive composition may be in the form of a liquid or
powder. Liquid form adhesives may provide advantages for certain
applications, such as where it is desirable to distribute a thin
film of adhesive over a large surface area. Dry blend adhesives may
provide advantages for certain applications, such as those where it
is desirable to minimize the amount of volatile compounds (e.g.,
water) in the adhesive composition.
[0288] A first type of dry blend adhesive composition may be formed
by mixing ground plant meal with one or more liquid or solid
additives. The liquid or solid additives are typically added in an
amount less than about 10% w/w of the plant meal. Alternatively,
the liquid or solid additives are may be blended with the plant
meal during grinding to form the ground plant meal. The ground
plant meal containing one or more additives is desirably a dry and
flowable material. Exemplary additives include intercalated clays,
partially exfoliated clays, exfoliated clays, mixture of a silicone
and a terpene compound (e.g., limonene), mineral oil, soy oil,
castor oil, soy methyl ester, canola methyl ester urea, glycerin,
propylene glycol, propylene carbonate, polyols, crosslinkers like
PMDI, lignin, epoxies such as glycidyl end-capped
poly(bisphenol-A-co-epichlorohydrin) (BPA) and trimethylolpropane
triglycidyl ether, polymer latexes, catalysts, fire retardants, and
wood preservatives.
[0289] A second type of dry blend adhesive composition may be
formed by mixing ground plant meal with a dry powder ingredient,
such as an additive that is not a liquid (e.g., a clay, an
intercalated clay, a partially exfoliated clay, an exfoliated clay,
or a silicone).
[0290] A third type of dry blend adhesive may be formed by mixing
the first type of adhesive (as described above) with any other dry
or liquid ingredient that may impart beneficial properties to the
adhesive composition.
[0291] The dry adhesives described above may be used as binders in
the manufacture of wood composites. Such wood composites may be
prepared by first mixing wood particulates with the dry blend
adhesive composition to form a mixture, and then subjecting the
mixture to elevated temperature and pressure to facilitate
densification and curing of the adhesive. The amount of cured
adhesive in the wood composite may be, for example, from about 0.2%
and 20% w/w of the cured wood composite.
VI. Applications of Adhesive Compositions
[0292] The adhesive compositions described herein can be used in a
variety of different applications, which include, for example,
bonding together many different types of substrates and/or creating
composite materials.
[0293] Accordingly, the invention provides a method of bonding a
first article to a second article. The method comprises the steps
of (a) depositing on a surface of the first article any one of the
foregoing adhesive compositions thereby to create a binding area;
and (b) contacting the binding surface with a surface of the second
article thereby to bond the first article to the second article.
The method optionally also comprises the step of, after step (b),
permitting the adhesive composition to cure, which can be
facilitated by the application of pressure, heat or both pressure
and heat.
[0294] The adhesive compositions can be applied to the surfaces of
substrates in any conventional manner. Alternatively, the surfaces
can be coated with the composition by spraying, or brushing, doctor
blading, wiping, dipping, pouring, ribbon coating, combinations of
these different methods, and the like.
[0295] The invention also provides a method of producing a
composite material. The method comprises the steps of (a) combining
a first article and a second article with any one of the foregoing
adhesive compositions to produce a mixture; and (b) curing the
mixture produced by step (a) to produce the composite material. The
curing can comprise applying pressure, heat or both pressure and
heat to the mixture.
[0296] The terms "substrate", "adherend" and "article" are
interchangeable and refer to the substances being joined, bonded
together, or adhered using the methods and compositions described
herein. In certain embodiments, the first article, the second
article or both the first and second articles are lignocellulosic
materials, or composite materials containing lignocellulosic
material. Furthermore, the first article, the second article or
both the first and second articles can comprise a metal, a resin, a
ceramic, a polymer, a glass or a combination thereof. It is
understood that the first article, the second article, or both the
first article and the second article can be a composite.
[0297] The compositions can be used to bond multiple
lignocellulosic materials (adherends) together to prepare composite
wood products. Furthermore, it is understood that at least one of
the adherends bonded together and/or included in the composite can
be wood, wood fiber, paper, rice hulls, fiberglass, ceramic,
ceramic powder, plastic (for example, thermoset plastic), cement,
stone, cloth, glass, metal, corn husks, bagasse, nut shells,
polymeric foam films or sheets, polymeric foams, fibrous materials,
or combinations thereof.
[0298] The amount of adhesive composition applied to the adhesive
bond between substrates may vary considerably from one end use
application, or type of adhesive used, or type of substrate, to the
next. The amount of adhesive should be sufficient to achieve the
desired bond strength and bond durability under a given set of test
conditions.
[0299] The amount of an adhesive composition applied may be in the
range of from about 5 to about 50 grams per square foot, from about
8 to about 60 grams per square foot, from about 10 to about 30
grams per square foot, from about 20 to about 50 grams per square
foot, from about 15 to about 40 grams per square foot, of bond
surface area (i.e., the bond surface area being the area of overlap
between the substrates to be bonded by the adhesive
composition).
[0300] The adhesive compositions can be used to fabricate
multi-substrate composites or laminates, particularly those
comprising lignocellulosic or cellulosic materials, such as wood or
paper. The adhesives can be used to prepare products such as
plywood, laminated veneer lumber (LVL), waferboard (also known as
chipboard or OSB), particle board, fiberboard, fiberglass,
composite wooden I-beams (I-joists), and the like.
[0301] The adhesive compositions can also be used to fabricate
composite materials, which include, for example, chip board,
particle board, fiber board, plywood, laminated veneer lumber,
glulam, laminated whole lumber, laminated composite lumber,
composite wooden I-beams, medium density fiberboard, high density
fiberboard, extruded wood, or fiberglass. The composite can be a
thermosetting composite or a thermoplastic composite. As described
above, the amount and identity of the components used to prepare
the composite can be selected to optimize the performance
properties of the composite. In one embodiment, the amount of
protein component is selected in order to optimize the performance
properties of the composite.
[0302] Accordingly, in certain other embodiments, the composite
comprises from about 0.5% to about 10% (w/w), from about 0.5% to
about 5% (w/w), from about 0.5% to about 3% (w/w), from about 1% to
about 10% (w/w), from about 1% to about 5% (w/w), or from about 1%
to about 3% (w/w) of ground plant meal or isolated polypeptide
composition. In certain other embodiments, the composite comprises
from about 0.1% to about 8% (w/w), from about 0.1% to about 5%
(w/w), from about 0.1% to about 3% (w/w), from about 0.5% to about
5% (w/w), from about 0.5% to about 3% (w/w), or from about 1% to
about 3% (w/w) of a polymeric material formed by reaction of the
prepolymer. In certain other embodiments, the composite comprises
from about 0.5% to about 10% (w/w), from about 0.5% to about 5%
(w/w), from about 0.5% to about 3% (w/w), from about 1% to about
10% (w/w), from about 1% to about 5% (w/w), or from about 1% to
about 3% (w/w) of formaldehyde scavenging agent (e.g.,
H.sub.2NC(O)NH.sub.2). In certain other embodiments, the composite
comprises from about 0.5% to about 10% (w/w), from about 0.5% to
about 5% (w/w), from about 0.5% to about 3% (w/w), from about 1% to
about 10% (w/w), from about 1% to about 5% (w/w), or from about 1%
to about 3% (w/w) of a diluent (e.g., glycerin, corn syrup, or a
mixture thereof). In certain other embodiments, the composite
comprises from about 0.001% to about 5% (w/w), from about 0.005% to
about 4% (w/w), from about 0.005% to about 2% (w/w), from about
0.05% to about 1% (w/w), from about 0.05% to about 2% (w/w), or
from about 0.05% to about 1% (w/w) of one or more additives, such
as an agent that improves moisture resistance, a pH modulator, a
composite-release promoter, or tacking agent.
[0303] In certain embodiments, the composite has an internal bond
strength of at least about 25 PSI, 40 PSI, 50 PSI, 70 PSI, 100 PSI,
120 PSI, or 150 PSI.
[0304] In certain embodiments where two-part adhesives are used,
Part-A and/or Part-B can be premixed with cellulosic components
such as wood fiber, sawdust (sometimes referred to as "furnish"),
or other components, and then mixed together and permitted to cured
to create a composite material. Alternatively, Parts A and B can be
mixed together before or during the addition of cellulosic
components. The resulting mixture is then permitted to cure to
create a composite material. Mixing can be accomplished using
conventional mixers such as paddle mixers, static mixers and the
like, currently known in the art.
[0305] Premixed components can be added to a sawdust cellulosic
component via spraying application or dripping application,
followed by rigorous mixing. Alternatively, each adhesive component
can be added to the sawdust sequentially ("sequential addition"),
simultaneously, in tandem ("tandem addition") without premixing,
and then the mixture is rigorously blended. Blending can be
achieved via any conventional mixing process including high speed
paddle mixing (e.g., with a Littleford blender or a Henchel-type
mixer), sigma-blade mixing, ribbon blending, etc. Additional
materials can also blended concurrently or sequentially with the
mixture including fillers such as calcium carbonate,
aluminosilicates, clays fumed silica, nano-sized inorganic
particulates, latex polymers, or antimicrobial compounds, etc.
[0306] Viscosity, sprayability, and/or spreadability of the
adhesive components can be controlled by adjusting the amount of
water added (or other liquid diluents such as glycerin and corn
syrup) to the Part-B component before it is premixed with Part-A,
or by adding water after the two components have been premixed.
When premixing is not employed (e.g., if tandem or sequential
mixing is employed), water can be added to the mixture as needed
for the purpose of influencing viscosity and sawdust-particle
surface coverage.
[0307] In another approach, for a two-part adhesive, Part-A and/or
Part-B can be mixed together along with cellulosic components such
as wood fiber, sawdust, or other components; blended with optional
polymeric components (e.g., virgin or recycled) plasticizers,
stabilizers, and other additives in liquid, pelletized, or powdered
form; and then extruded via single screw or twin screw extrusion
methods to create cured composite products such as rail ties,
fencing posts, firring strips, decking, etc. The extrudate can be
used to feed an injection molding machine for the purpose of
fabricating molded parts such as garage door panels, car door
panels, cabinet doors, toilet seats, and the like.
[0308] Adhesive compositions made using ground plant meal can
provide advantages in certain situations because the use of ground
plant meal allows for an adhesive composition comprising less
water. It is often desirable to use an adhesive composition
containing less water because cure of the adhesive may use elevated
temperatures which converts the water to steam, partially
complicating the procedures used to cure the adhesive. A related
benefit of using an adhesive composition containing ground plant
meal is that it permits more adhesive to be applied to the
components being bound together. This helps ensure that the
components being bound together are adequately coated with
adhesive, which facilitates strong bonding between the components
upon curing the adhesive.
[0309] Composite products can be prepared using a binder containing
a formaldehyde scavenging agent, such as urea. The amount of urea
can be adjusted based the on particular end-use application of the
composite, such as interior use (where more formaldehyde scavenging
agent is desired to minimize formaldehyde emissions) or exterior
use (where less formaldehyde scavenging agent may be acceptable
because the formaldehyde emission standards are less critical for
exterior applications).
[0310] Under certain circumstances, pressure and/or heat can be
used to facilitate curing. The amount of pressure and the time
period for which the pressure is applied are not limited and
specific pressures and times will be evident to one skilled in the
art from the present disclosure (see the various Examples). In
certain embodiments, a pressure of approximately 10 to 250 psi is
applied from about 2 minutes to about 2 hours, from about 10
minutes to about 2 hours, from about 2 minutes to about 30 minutes,
or from about 10 minutes to about 30 minutes (depending on the
temperature). The pressure, heating, or application of both
pressure and heat may decrease the viscosity adhesive compositions
described herein, facilitating their flow in the contact area, such
that a bonding region is created whereby there is a continuum
between the adherends. The amount of pressure, heat time or their
combination can be optimized to ensure such continuum and will
depend on the adherends' physical or chemical properties as well as
on the rate of the adhesive's viscosity-build throughout the cure
cycle.
[0311] Depending upon the adhesive used, the resulting article can
be moisture resistant. Furthermore, the article may remain intact
after boiling in water for 5 minutes, 10 minutes, 30 minutes, 1
hour, 2 hours, or 3 hours. Furthermore, two or more components of
the article may remain bonded after boiling in water for 5 minutes,
10 minutes, 30 minutes, 1 hour, 2 hours or 3 hours. Furthermore,
the article when boiled in water for 5 minutes, 10 minutes or 30
minutes, may display less than a 20% increase, or less than a 10%
increase in volume relative to the article prior to exposure to the
water.
[0312] Furthermore, when the article (for example, a composite
material, a laminate, or a laminate containing a composite
material) contains a lignocellulosic material, the article exhibits
no less than 75% cohesive failure of the lignocellulosic component
when the article is placed under a loading stress sufficient to
break the article. In certain embodiments, when an article
(resulting product) contains a lignocellulosic material, the
article has a block shear strength as measured under the D905 and
D2559 ASTM standards of greater than 3,000 lbs., 4,000 lbs., 5,000
lbs. or 6,000 lbs.
VII. Emulsions
[0313] In another aspect, the invention provides a stable emulsion
or dispersion, for example, an aqueous emulsion or dispersion,
comprising (a) from about 1% to about 90% (w/w) of an oil, (b) at
least one first additive selected from the group consisting of a
partially exfoliated clay, an exfoliated clay, an intercalated
clay, cellulose nanoparticles, and a mixture of a silicone and a
terpene compound, and (c) from about 1% to about 99% (w/w) of a
protein composition selected from the group consisting of i) ground
plant meal and ii) an isolated polypeptide composition, wherein the
protein composition produces a stable emulsion or dispersion of the
oil in an aqueous medium.
[0314] In certain other embodiments, the stable emulsion or
dispersion comprises an isolated protein composition capable of
being dispersed in water and comprises one or more of the following
features: (i) a prominent amide-I absorption band between about
1620 cm.sup.-1 and 1645 cm.sup.-1, (ii) an amide-II band between
approximately 1514 cm.sup.-1 and 1545 cm.sup.-1, as determined by
solid state FTIR, and (iii) is capable of dispersing an
oil-in-water or water-in-oil to produce a homogeneous emulsion that
is stable for least 5 minutes.
[0315] In still other embodiments, the stable emulsion or
dispersion comprises an isolated protein composition capable of
being dispersed in water and comprises one or more of the following
features: (i) an amide-I absorption band between about 1620
cm.sup.-1 and 1642 cm.sup.-1 and an amide-II band between
approximately 1514 cm.sup.-1 and 1540 cm.sup.-1, as determined by
solid state FTIR, (ii) a prominent 2.degree. amide N--H stretch
absorption band centered at about 3275 cm.sup.-1, as determined by
solid state FTIR, and (iii) is capable of dispersing an
oil-in-water or water-in-oil to produce a homogeneous emulsion that
is stable for least 5 minutes.
[0316] In certain other embodiments, the stable emulsion or
dispersion comprises an isolated protein composition capable of
being dispersed in water and comprises one or more of the following
features: (i) an amide-I absorption band between about 1620
cm.sup.-1 and 1632 cm.sup.-1 and an amide-II band between
approximately 1514 cm.sup.-1 and 1521 cm.sup.-1, as determined by
solid state FTIR, (ii) a prominent 2.degree. amide N--H stretch
absorption band centered at about 3272 cm.sup.-1, as determined by
solid state FTIR, (iii) an average molecular weight of between
about 600 and about 2,500 Daltons (determined using, for example,
MALDI mass spectrometry), (iv) two protonated nitrogen clusters
defined by .sup.15N chemical shift boundaries at about 86.2 ppm and
about 87.3 ppm, and .sup.1H chemical shift boundaries at about 7.14
ppm and 7.29 ppm for the first cluster, and .sup.1H chemical shift
boundaries at about 6.66 ppm and 6.81 ppm for the second duster, as
determined by solution state, two-dimensional proton-nitrogen
coupled NMR, and (v) is capable of dispersing an oil in water to
produce a homogeneous emulsion that is stable for least 5
minutes.
[0317] The oil referenced above can be selected from the group
consisting of an organic polyisocyanate (for example, PMDI,
4,4'-methylenediphenyl, diisocyanate (4,4'-MDI),
2,4-methylenediphenyl, diisocyanate (2,4-MDI),
2,2-methylenediphenyl, diisocyanate (2,2-MDI), monomeric MDI, or
PMDI that has been reacted with a hydroxyl-functional compound such
as a polyol), mineral oil, soybean oil, derivatized soybean oil,
motor oil, castor oil, derivatized castor oil, dibutyl phthalate,
epoxidized soybean oil, corn oil, vegetable oil, caprylic
triglyceride, Eucalyptus oil, tributyl o-acetylcitrate, linseed
oil, an adipate ester, a sebacate ester, a phthalate ester, and a
citrate ester.
[0318] In certain other embodiments, the protein composition is
used to provide a stable emulsion or dispersion, for example, an
aqueous emulsion or dispersion, comprising a protein composition
described herein and one or more of the following hydrophobic
liquids and hydrophobic solids: a silicone (e.g., a silicone oil or
a silicone gel), a fluorocarbon (e.g., a solid wax fluorocarbon
(e.g., a fluoroalkyl wax) or a liquid oil fluorocarbon (e.g., a
fluoroalkyl liquid)), a fluorinated polyol, a wax (e.g., a solid
carboxylic acid ester (e.g., an ester of stearic acid), a salt of a
carboxylic acid (e.g., a salt of stearic acid, e.g., zinc
stearate), a hydrocarbon wax, and a fluorinated hydrocarbon wax), a
liquid carboxylic acid ester that is hydrophobic, and a liquid
hydrocarbon.
[0319] In certain other embodiments, the protein composition is
used to provide a stable emulsion or dispersion, for example, an
aqueous emulsion or dispersion, comprising a protein composition
described herein and an agent selected from the group consisting of
BE Square 165 Amber Petroleum Microcrystalline Wax from Baker
Hughes, Inc.; FluoroLink D-10 Fluorinated polyol from Solvay
Solexis, Inc; Tego Protect-5000 functionalized silicone fluid from
Evonik Tego Chemie GmbH; Soy Lecithin; Castor Oil; Zinc Stearate;
Dow Corning FS-1265 Fluid, 300 cST (Trifluoropropyl Methicone) from
Dow Corning; and T-Sil-80, hydroxy terminated polydimethylsiloxane
from Siovation, Inc.
[0320] Throughout the description, where compositions and articles
are described as having, including, or comprising specific
components, or where processes and methods are described as having,
including, or comprising specific steps, it is contemplated that,
additionally, there are compositions and articles of the present
invention that consist essentially of, or consist of, the recited
components, and that there are processes and methods according to
the present invention that consist essentially of, or consist of,
the recited processing steps.
[0321] Additional adhesive compositions, emulsions, methods of
making adhesive compositions, methods of using adhesive
compositions, and articles are described in U.S. patent application
Ser. Nos. 12/719,521 and 13/154,607, the contents of which are
hereby incorporated by reference.
[0322] Practice of the invention will be more fully understood from
the foregoing examples, which are presented herein for illustrative
purposes only, and should not be construed as limiting the
invention in any way.
EXAMPLES
Example 1
Isolation of Polypeptide Compositions
[0323] Exemplary procedures for isolating and characterizing the
water-insoluble polypeptide composition, water-soluble polypeptide
composition, or a mixture thereof are described below.
Procedure A: Preparation of Water-Insoluble Polypeptide Composition
and Preparation of Water-Soluble Polypeptide Composition.
[0324] Everlase digested protein from castor (experimental sample
lot 5-90) was obtained from Prof S. Braun at the Laboratory of the
Department of Applied Biology at the Hebrew University of
Jerusalem, Israel. Digested castor can be prepared as follows:
castor meal protein is suspended in water at the ratio of about
1:10 w/w. Calcium chloride is added to an effective concentration
of about 10 mM, and the pH of the suspension adjusted to pH 9 by
the addition of 10N NaOH. The reaction is then heated to 55.degree.
C. while stirring. Next, Everlase 16L Type EX.RTM. (NOVOZYMES') is
added at the ratio of 20 g per kg of castor meal protein, and the
mixture is stirred at the same temperature for about 4 hours.
Finally, the resulting mixture is brought to a pH 3.5 with citric
acid and spray-dried to provide a powder.
[0325] The Everlase digested protein from castor (lot 5-90) was
fractionated to yield a water-soluble fraction, and a
water-insoluble, dispersible fraction. In the first step, 300 g of
digested castor was slurried into 1 liter of distilled water. The
mixture was shaken by hand, and was then placed into a sonicator
bath for a period of 30 minutes. The slurry then was removed and
was allowed to set idle for a period of up to two days to allow the
insoluble portion to settle (in separate experiments, it was found
that centrifuging was equally adequate). At that point, the clear
yellow/amber supernatant was pipetted away and was retained for
future use. Fresh distilled water was then added to the sediment to
bring the total volume back to the 1-Liter mark on the container.
The process of shaking, sonicating, settling, supernatant
extracting, and replenishing with fresh distilled water (washing)
then was repeated (6 times in total). In the final step, the water
was pipetted from the top of the grayish-black sediment, and the
sediment was then dried in a vacuum oven at 45.degree. C. Based on
the sediment's dry weight, the water-insoluble/water-dispersible
polypeptide fraction was determined to comprise of approximately
50% by weight of the digested castor. Separately, the 1.sup.st and
2.sup.nd supernatants were combined and were then dried to yield a
transparent yellow-colored, water-soluble polypeptide fraction.
[0326] After drying the fractions, it was verified that the
grayish-black sediment (the water-insoluble and dispersible
fraction) could not be re-dissolved in water. On the other hand,
the dried supernatant fraction (clear/amber, glassy solid) was
completely soluble in water.
[0327] The two fractions were separately analyzed by solid state
FTIR (see FIGS. 4-6). The spectra in FIG. 4 show that carboxylate
and amine salt moieties are primarily associated with the
water-soluble fraction. FIG. 5 shows that the amide carbonyl
stretch band and the amide N--H bend bands are shifted to higher
wavenumbers in the water-soluble polypeptide fraction. These
components also appear to be present in the water-insoluble
dispersible polypeptide fraction, but the predominant amide-I and
amide-II bands are shifted to lower wavenumbers. Aside from
hydrogen bonding effects, these differences also appear to be
related to the presence of a higher fraction of primary amide
groups in the water-soluble polypeptide fraction, and to a higher
fraction of secondary amide groups in the water-dispersible
polypeptide fraction (from the main-chain polypeptide chains). This
is corroborated by the N--H stretching region depicted in FIG.
6.
[0328] FIG. 6 shows solid state FTIR spectra of isolated fraction
from digested castor where the N--H stretching region from FIG. 4
is expanded. The spectra were vertically scaled to achieve
equivalent absorbance intensities for the secondary amide N--H
stretch band centered at 3275 cm.sup.-1. FIG. 6 shows that the
predominant type of amide in the water-dispersible fraction is the
secondary main-chain amide as evidenced by the single, highly
symmetric band centered at 3275 cm.sup.-1. Although the
water-soluble fraction also contains this type of amide, it also
contains significantly higher fractions of primary amides as
evidenced by the presence of the two primary N--H stretching bands
at approximately 3200 cm.sup.-1 (symmetric) and at approximately
3300 cm.sup.-1 (asymmetric), respectively.
[0329] These spectra show that the water-soluble polypeptide
fraction contained a relatively high concentration of primary
amines, free carboxylic acids, acid salts, and amine salts.
Conversely, the water-insoluble/water-dispersible polypeptide
fraction had a higher fraction of secondary amides. In addition,
the amide-I carbonyl absorption band for the
water-insoluble/water-dispersible fraction was observed to appear
at a wavenumber of approximately 1625 cm.sup.-1, whereas that of
the water-soluble fraction was observed at approximately 1640
cm.sup.-1. As will be discussed elsewhere, this feature is one of
the distinguishing differences between the water-soluble and
water-insoluble polypeptide fractions; not only for castor
proteins, but for soy proteins and canola proteins as well.
Procedure B: Additional Procedure for Preparation of
Water-Insoluble Polypeptide Composition and Preparation of
Water-Soluble Polypeptide Composition.
[0330] Digested soy protein was obtained as an experimental sample
(lot 5-81) from Prof S. Braun, the Laboratory of Applied Biology at
the Hebrew University of Jerusalem, Israel. The digested soy
protein was prepared as follows. Soy protein isolate (Soy protein
isolate SOLPRO 958.RTM. Solbar Industries Ltd, POB 2230, Ashdod
77121, Israel) was suspended in water at a ratio of 1:10 (w/w). The
pH of the suspension was adjusted to pH 7 with 10N NaOH, and was
then heated to 55.degree. C. while stirring. Neutrase 0.8 L.RTM.
(NOVOZYMES') then was added at a ratio of 20 g per kg of soy
protein, and the mixture was stirred at the same temperature for 4
hours. The resulting mixture (pH 6.5) was spray-dried to yield a
light tan powder.
[0331] Digested soy (lot 5-81) was fractionated to yield a
water-soluble polypeptide fraction, and a
water-insoluble/water-dispersible polypeptide fraction. In the
first step, 300 g of digested soy was slurried into 1 liter of
distilled water. The mixture was shaken by hand, and was then
placed into a sonicator bath for a period of 30 minutes. Aliquots
were placed into centrifuge tubes, and the tubes were then spun at
3,400 rpm for a period of approximately 35 minutes. The centrifuged
supernatant, which contained the water-soluble fraction, was
decanted off of the remaining water-insoluble sediment, and was
poured into a separate container for later use (this clear yellow
supernatant was placed into an open pan and was allowed to
evaporate dry at a temperature of 37.degree. C.). After the first
washing step, fresh distilled water was then added to the tubes,
and the remaining sediment was dispersed into the water by means of
hand-stirring with a spatula. The combined centrifugation,
decanting, and re-dispersion procedures were performed for a total
of 5 cycles. After the final cycle, the free liquid containing
residual water-soluble protein was decanted from the residual
paste-like dispersion (yellowish-peach in color). The resulting
dispersion (gravimetrically determined to be 16.24% solids by
weight) contained the water-insoluble/water-dispersible
proteins.
[0332] The paste-like dispersion was observed to be stable for a
period of several weeks. It was also discovered that the dispersion
could be readily combined with water-soluble polymers, and with
water-dispersible polymer latexes. Moreover, the dispersion was
readily compatible with PMDI (a stable dispersion was formed when
PMDI was added to the slurry, and there was no evidence of PMDI
phase separation, even after 24 hours). By contrast, neither the
water soluble extract from the digested soy, nor the digested soy
itself was capable of stabilizing a dispersion of PMDI in
water.
[0333] After drying aliquots of both fractions, it was verified
that the yellow sediment (the water-insoluble/water-dispersible
extract) could not be re-dissolved in water. On the other hand, the
dried supernatant fraction (clear/yellow solid) was completely
soluble in water. The two dried extracts were separately analyzed
by solid state FTIR (see FIGS. 7-10). FIG. 8 shows overlaid solid
state FTIR spectra of isolated fractions from digested soy, where
the N--H region is expanded. The spectra were vertically scaled to
achieve equivalent absorbance intensities for the secondary amide
N--H stretch band centered at 3275 cm.sup.-1. FIG. 8 shows that the
predominant type of amide in the water-dispersible fraction is the
secondary main-chain amide as evidenced by the single, highly
symmetric band centered at 3275 cm.sup.-1. Although the
water-soluble polypeptide fraction also contains this type of
amide, it also contains significantly higher fractions of primary
amides as evidenced by the presence of the two primary N--H
stretching bands at approximately 3200 cm.sup.-1 (symmetric) and at
approximately 3300 cm.sup.-1 (asymmetric), respectively.
Collectively, these spectra revealed that the water-soluble
polypeptide fraction was comprised of a relatively high
concentration of primary amines Conversely, the water-insoluble,
dispersible polypeptide fraction was comprised of a higher fraction
of secondary amines.
[0334] As shown in FIG. 7, the amide carbonyl stretch band and the
amide N--H bend band are shifted to higher wavenumbers in the
water-soluble fraction. These components also appear to be present
in the water-insoluble dispersible fraction, but the predominant
amide-I and amide-II bands are shifted to lower wavenumbers. Aside
from hydrogen bonding effects, these differences appear to be
related to the presence of a higher fraction of primary amide
groups (and/or primary amines) in the water-soluble polypeptide
fraction (from lower molecular weight amino acid fragments), and to
a higher fraction of secondary amide groups in the
water-dispersible polypeptide fraction (from the main-chain
polypeptide chains). This is supported by the N--H stretching
region depicted in FIG. 6.
[0335] FIG. 8 shows that the predominant type of amide in the
water-dispersible fraction is the secondary main-chain amide as
evidenced by the single, highly symmetric band centered at 3275
cm.sup.-1. Although the water-soluble fraction also contains this
type of amide, it also contains significantly higher fractions of
primary amines as evidenced by the presence of the two primary N--H
stretching bands at 3200 cm.sup.-1 (symmetric) and at approximately
3300 cm.sup.-1 (asymmetric), respectively.
[0336] In spite of being derived from different plant sources, the
water-insoluble dispersible fractions from digested soy and
digested castor are spectrally similar to one another (see FIG.
14). Conversely, the water-soluble polypeptide fractions appear to
have different FTIR spectral characteristics (see FIG. 12).
Further, MALDI mass spectroscopic indicates the water-soluble
polypeptide fractions from digested soy and digested castor have
different molecular weight characteristics. The commonality between
the two types of water-soluble fractions is that they both appear
to contain primary amines/amides.
Procedure C: Additional Procedure for Preparation of
Water-Insoluble Polypeptide Composition and Preparation of
Water-Soluble Polypeptide Composition
[0337] Castor meal (4.0 kg containing 24.8% protein) was suspended
in 0.1M NaOH at a 10:1 w/w meal to alkali ratio. The suspension was
stirred for 18 hours at ambient temperature and the solids were
then removed by centrifugation. The supernatant (about 32 liters)
was acidified to pH 4.5 with 10N HCl. The protein was allowed to
sediment at about 10.degree. C. for 12 hours, the clear supernatant
solution was decanted, and the heavy precipitate (about 2 kg) was
collected by centrifugation. The wet precipitate was freeze-dried
yielding 670 g protein isolate.
[0338] The water-insoluble and water-soluble polypeptide fractions
were obtained by means of extraction with water. In the first step,
10 g of the castor protein isolate (lot 5-94) was slurried into 50
g of distilled water. The mixture was dispersed via mechanical
stirring for 2 hours. Aliquots then were placed into centrifuge
tubes, and the tubes were then spun at 3,400 rpm for a period of
approximately 35 minutes. The centrifuged supernatant, which
contained the water-soluble fraction, was decanted from the
remaining water-insoluble sediment, and was poured into a separate
container (this clear yellow supernatant was saved and dried at
37.degree. C. for subsequent dispersion experiments and solid state
FTIR analyses). After the first washing step, fresh distilled water
was then added to the tubes, and the remaining sediment was
dispersed into the water by means of hand-stirring with a spatula.
The combined centrifugation, decanting, and re-dispersion
procedures were performed for a total of 13 cycles. After the final
cycle, the free liquid was decanted from the residual paste-like
dispersion (the water-insoluble polypeptide fraction from the
starting castor protein). Upon drying, the paste was determined to
contain 28.58% solids, and the total yield of the water-insoluble
fraction was determined to be 62.87%. Thus, the starting castor
protein itself contained 62.87% water-insoluble polypeptide
material, and 37.12% water-soluble polypeptide material.
Procedure D: Preparation of Digested Whey Protein.
[0339] Digested whey protein (lot 5-72, referred to herein as
digested whey protein pH 6.5) was obtained as an experimental
sample from Prof. S. Braun, the Laboratory of Applied Biology at
the Hebrew University of Jerusalem, Israel, and was prepared as
follows; Whey protein (WPI-95.RTM. Whey Protein Isolate;
Nutritteck, 24 Seguin Street, Rigaud, QC, Canada J0P 1P0) was
suspended in water at a ratio of 1:6 (w/w). The pH of the
suspension was adjusted to pH 7 with 5N NaOH, and was heated to
55.degree. C. while stirring. FLAVOURZYME 500MG.RTM. (from
NOVOZYMES') then was added at a ratio of 20 g per kg of whey
protein, and the mixture was stirred at the same temperature for 4
hours. The resulting aqueous mixture was pH 6.5. The resulting
mixture then was spray-dried to yield digested whey protein as a
pale yellow powder containing a mixture of water-soluble and
water-insoluble polypeptide.
[0340] Procedure E: Preparation of Digested Castor Protein Reacted
with Sodium Nitrite.
[0341] Castor meal protein was suspended in water at a ratio of
1:10 (w/w). Calcium chloride was added at an effective
concentration of 10 mM, and the pH of the suspension was adjusted
to pH 9 by the addition of 10N NaOH. The reaction was heated to
55.degree. C. while stirring. Everlase 16L Type EX.RTM.
(NOVOZYMES') then was added at a ratio of 10 g per kg of castor
meal protein, and the mixture was stirred at the same temperature
for 4 hours. L-lactic acid (90%, 120 g per kg castor protein) then
was added to bring the mixture to pH 4.4 followed by gradual
addition (over a 20 hour period) of sodium nitrite solution in
water (0.4 kg/1, 0.4 liter per kg castor protein) while stirring.
The reaction then was left to stand at ambient temperature for 40
hours. Na.sub.2S.sub.2O.sub.5 (0.2 kg per kg castor protein) was
then added, and the reaction was heated to 60.degree. C. and
stirred for 15 minutes. After cooling to ambient temperature, the
reaction was brought to pH 2.0 with concentrated HCl. It was then
left at 10.degree. C. for 18 hours, and the resulting precipitate
was separated by centrifugation for 15 minutes at 24,000.times.g.
The precipitate was re-suspended in 10 mM citric acid (3 vol. per
vol. precipitate), and then it was collected and subsequently
freeze-dried to yield a tan powder containing a mixture of
water-soluble and water-insoluble polypeptide.
Procedure F: Isolation of Water-Insoluble/Water-Dispersible Protein
Fraction and Water-Soluble Protein Fraction by Washing Ground Soy
Meal with Water, and Characterization of Same
Part I: Isolation of Water-Insoluble/Water-Dispersible Protein
Fraction and Water-Soluble Protein Fraction
[0342] Soy meal (same as Example 1) having a particle size range of
20-70 .mu.m was mixed with distilled water (pH approximately 7) to
yield a 27.83% meal dispersion in water (w/w). In the first "wash"
step, an aliquot of the dispersion was centrifuged for 60 minutes,
and the clear supernatant containing a water-soluble protein
fraction was decanted from the wet slurry that remained on the
bottom of the centrifuged tube (in a separate experiment, this wet
slurry was gravimetrically determined to contain approximately 33%
solids in water (w/w); and the supernatant was gravimetrically
determined to contain approximately 15% by weight solids (w/w)).
The yield of the water-insoluble/water-dispersible protein fraction
after the first "wash" step was determined to be approximately 80%
of the starting meal weight.
[0343] In a second step, the 33% solids fraction from the first
wash step was mixed and dispersed in fresh distilled water (pH
approximately 7), and the dispersion was centrifuged for a second
time. Again, the clear supernatant was decanted, and the remaining
slurry was subjected to a third wash cycle (addition of fresh
distilled water followed by centrifuging). After the third "wash"
step and supernatant decanting, the resulting slurry of
water-insoluble/water-dispersible protein fraction was
gravimetrically determined to contain approximately 24% solids, and
the yield was determined to be approximately 53% of the starting
meal weight. Thus, the ground soy meal itself was comprised of
approximately 53% of a water-insoluble/water-dispersible protein
fraction, and approximately 47% of a water-soluble protein
fraction.
Part II: Disperion Analysis for Water-Insoluble/Water-Dispersible
Protein Fraction, Water-Soluble Protein Fraction, and Ground Soy
Meal
[0344] An aliquot of the 24% solids dispersion of the isolated
water-insoluble/water-dispersible protein fraction (washed 3 times
as noted above) was blended with PMDI at a w/w ratio of 1 part PMDI
to 1 part of protein fraction. The resulting mixture formed a
stable dispersion, and remained stable during a 1 hour period of
observation with no visual signs of phase separation.
[0345] In order to test dispersion ability of ground soy meal, a
dispersion of 24% (w/w) ground soy meal in water was mixed with
PMDI at a 1:1 w/w ratio of PMDI to soy meal solids. The soy meal
comprised approximately 53% by weight of a
water-insoluble/water-dispersible protein fraction and
approximately 47% by weight of a water-soluble protein fraction.
The mixture of ground meal and PMDI formed a stable dispersion
which remained stable during a 1 hour period of observation with no
visual signs of phase separation.
[0346] In order to test dispersion ability of water-soluble protein
faction, water-soluble protein fraction obtained from the soy meal
(by first washing the soy meal, then isolating the water-soluble
fraction by drying the supernatant after centrifuging) was
dissolved in water to yield a 24% solids solution (w/w). When PMDI
was added to this solution (at a 1:1 weight ratio of PMDI to
water-soluble protein fraction), the resulting mixture was
unstable, and phase separation was visually evident--immediately
after mixing.
[0347] The experimental results above demonstrate that
water-emulsified PMDI-containing adhesive compositions can be
prepared with i) water-insoluble/water-dispersible protein
fractions obtained by washing ground plant meals, and ii) ground
plant meal compositions that are comprised of both a
water-insoluble/water-dispersible protein fraction and a
water-soluble protein fraction. The water-soluble protein fraction
does not facilitate dispersion, but the
water-insoluble/water-dispersible protein fraction is present in an
amount sufficient to facilitate dispersion.
[0348] Various commercially available compositions derived from
plant meals, such as soy flour, are solvent-extracted which result
in removal of water-insoluble protein components. Such compositions
are unable to facilitate dispersion, and, thus, are less desirable
for use making an adhesive.
Part III: FTIR Analysis of Water-Insoluble/Water-Dispersible
Protein Fraction, Water-Soluble Protein Fraction, and Ground Soy
Meal
[0349] Solid state surface ATR FTIR experiments were performed on
water-insoluble/water-dispersible protein fraction (this sample was
collected after the third wash cycle and was allowed to dry at
23.degree. C., and water-soluble protein fraction (this sample was
collected from the clear supernatant after the third wash cycle,
and was allowed to dry at 23.degree. C. to yield a transparent
amber solid) obtained by washing soy meal with water.
Characteristics of the FTIR spectra are described below.
[0350] FIG. 18 shows the solid state FTIR spectra for the isolated
water-insoluble/water-dispersible protein fraction from soy meal
together with the water-soluble protein fraction where the N--H
stretching region has been expanded. The spectra were vertically
scaled to achieve equivalent absorbance intensities for the
secondary amide N--H stretch band centered at 3275 cm.sup.-1. FIG.
18 shows that the predominant type of amide in the
water-insoluble/water-dispersible protein fraction is the secondary
main-chain amide as evidenced by the single, highly symmetric band
centered near 3275 cm.sup.-1. Although the water-soluble fraction
also contains this type of amide, it also contains significantly
higher fractions of primary amides as evidenced by the presence of
the two primary N--H stretching bands at approximately 3200
cm.sup.-1 (symmetric) and at approximately 3300 cm.sup.-1
(asymmetric), respectively.
[0351] As shown in FIG. 19, the amide-I carbonyl absorption band
for the water-insoluble/water-dispersible protein fraction was
observed to appear at a wavenumber of approximately 1629 cm.sup.-1,
whereas that of the water-soluble protein fraction was observed to
appear at approximately 1650 cm.sup.-1. This feature is one of the
distinguishing differences between the water-soluble protein
fraction and water-insoluble/water-dispersible protein fraction,
not only for isolated polypeptides from castor and soy proteins,
but for protein-containing fractions that are isolated directly
from plant meals like soy meal. Moreover, the amide-II band for the
water-insoluble/water-dispersible protein fraction was observed to
appear as a broad band centered at approximately 1526 cm.sup.-1,
whereas that of the water-soluble protein fraction was observed to
appear at approximately 1580 cm.sup.-1 together with a weak
shoulder at approximately 1547 cm.sup.-1.
Example 2
Characterization of Polypeptide Compositions by Mass
Spectrometry
[0352] This Example describes characterization of the various
protein samples via MALDI Mass Spectrometry using an Ultraflex III
instrument from Bruker.
[0353] The instrument was set in positive mode, in order to detect
positive ions generated during the ionization process. The voltage
applied to accelerate the ion into the TOF analyzer was set at 25
KV. The analysis was carried out by using the instrument in
reflection mode which improves the resolution. Solid samples were
dissolved in DMSO at a concentration of 10 mg/mL. Water-soluble
supernatant fractions which were solvated in water.
[0354] Each sample solution was mixed with a matrix solution (for
analytical purposes). The matrix was an inert compound of low
molecular weight which absorbs at the same wavelength of the laser,
Nd:YAG 355 nm. The matrices used were: .alpha.-CHCA,
alpha-cyano-4-hydroxycinnamic acid, dissolved in a solution of
ACN/H.sub.2O (70:30) with 0.1% of TFA at a concentration of 10
mg/mL; and DCTB,
T-2-[3-(4-t-Butyl-phenyl)-2-methyl-2-propenylidene]malononitrile,
dissolved in THF at a concentration of 10 mg/mL. The first matrix
was mainly used for the analysis of peptides and proteins while the
second one, DCTB, was suitable for the analysis of polymers.
[0355] The matrix solutions and the sample solutions were mixed at
a 10:1 volume ratio respectively. For the analysis where DCTB was
used as matrix, NaTFA (10 mg/mL in THF) was added to the solution
matrix/sample as a cationizing agent at a ratio 10:2:1 by volume
(matrix:sample:salt, respectively). 0.8 .mu.L of the resulting
solutions were spotted on a target plate made of polished steel,
and only after the solvents were completely dried was the target
loaded into the instrument. The spectra were collected and
manipulated by using FlexAnalysis software released by Bruker
Daltonics.
[0356] Relative fragment intensities were normalized and used to
calculate number average (Mn), weight average (Mw), and z-average
(Mz) molecular weight parameters for various samples. The results
are summarized in Table 2.
TABLE-US-00002 TABLE 2 Sample ID Mn Mw Mz Mw/Mn Castor protein
isolate lot 5-94 .sup.1 1149 1162 1179 1.01 Digested castor lot
5-83 .sup.2 951 1081 1250 1.13 Digested castor lot 5-108 .sup.3 897
1011 1169 1.12 Digested castor Water-insoluble/ 1009 1371 1928 1.35
dispersible fraction (lot 5-108) .sup.3 Digested castor
Water-soluble 1532 1697 1894 1.10 fraction (lot 5-108) .sup.3 Soy
Protein Isolate 2023 2104 2161 1.03 Digested Soy (lot 5-81) .sup.4
894 989 1104 1.10 Digested Soy Water-insoluble/ 910 1119 1512 1.22
dispersible fraction (lot 5-81) .sup.4 Digested Soy Water-soluble
837 888 941 1.06 fraction (lot 5-81) .sup.4 .sup.1 see Example 1,
Procedure C .sup.2 Castor meal protein digested with Everlast (Lot
No. 5-83) ws obtained from Prof. Sergei Braun of The Hebrew
University of Jerusalem .sup.3 see Example 4 .sup.4 see Example 1,
Procedure B
[0357] The results indicate that the molecular weight
characteristics (as determined by MALDI mass spectroscopy) of the
polypeptide composition can depend on the process used to obtain
the polypeptide composition. For example, castor protein isolate
was observed to have a higher number average molecular weight than
its digested counterpart. Further, upon digestion, the number
average molecular weight was observed to decrease while the
polydispersity increased. The same trend was observed for the soy
protein isolate and its digested counterpart.
[0358] Other experimental results indicate that proteins in the
water-soluble polypeptide composition from digested castor have a
higher number average molecular weight than its parent protein
isolate. However, proteins in the water-soluble polypeptide
composition from digested soy had a lower number average molecular
weight than its parent soy protein isolate.
[0359] Collectively, these results indicate that it is possible to
prepare compositions that both i) have particular molecular weight
features, and ii) have the ability to disperse an oil in water or
water in oil, by selecting a particular procedure for preparing the
polypeptide composition.
Example 3
Characterization of Polypeptide Compositions by Two-Dimensional
Proton-Nitrogen NMR Correlation Spectra and Characterization of a
Water-Insoluble/Water-Dispersible Polypeptide Fraction
[0360] The water-insoluble and water-soluble protein fractions were
prepared as follows. Digested castor (lot 5-83) was suspended in
water at the ratio of 1:10 w/w. Calcium chloride was added to the
effective concentration of 10 mM, and the pH of the suspension was
adjusted to pH 9 by the addition of 10N NaOH. The reaction was
heated to 55.degree. C. while stirring. Everlase 16L Type EX.RTM.
(NOVOZYMES') then was added at the ratio of 10 g per kg of castor
meal protein, and the mixture was stirred at the same temperature
for 4 hours. The resulting mixture then was brought to a pH 3.5
with citric acid and was spray-dried to yield a tan powder. Then,
the water-insoluble and water-soluble protein fractions were
harvested as described in Example 1 (Procedure A) and were allowed
to air-dry at 23.degree. C.
[0361] The dried powder containing the water-insoluble protein
fraction was dissolved in d6-DMSO (6.8% by weight) to yield a red
homogeneous solution (Sample A). An aliquot of the as-made dried
digested castor was also dissolved in d6-DMSO (6.8% solids by
weight) to yield a comparative homogeneous red solution (Sample B).
Solid-state FTIR analyses of the same dried powders revealed
distinct differences in both the N--H stretching and carbonyl
stretching regions of the solid state FTIR spectra. These spectral
differences were attributed to differences in bonding environments
for the polypeptide N--H moieties, possibly resulting from
differences in secondary and tertiary structure. One of the
specific differences involved a shift to lower wavenumbers for the
amide-I carbonyl band in the water-insoluble/water-dispersible
fraction. In order to further characterize these types of
differences, a two-dimensional NMR technique was employed for the
purpose of characterizing a very specific subset of bonded atomic
nuclei; namely, protons bonded to nitrogens.
[0362] The samples were dissolved in DMSO-d6 and were placed into 5
mm NMR tubes. All .sup.1H NMR spectra were recorded on a Varian
NOVA 750 MHz spectrometer equipped with an HCN-PFG (pulsed field
gradient) triple resonance Cryo Probe at 30.degree. C. For
one-dimensional (1D).sup.1H NMR spectra, a spectral window of 10000
Hz was used with an acquisition time of 3 seconds and relaxation
delay of 5 seconds. The spectra were signal averaged for 16
transients using a proton 90.degree. pulse width of 8.6
microseconds. The spectral data were zero filled to 132 k points
and were processed with 1 Hz line broadening, then baseline
corrected and referenced to an internal residual solvent DMSO-d6
peak at 2.50 ppm before integrating and making plots.
[0363] Phase sensitive two-dimensional (2D).sup.1H--.sup.15N
gradient-HSQC (heteronuclear single quantum coherence) data were
collected with 2048 acquisition points in the F2 dimension and 768
points in the F1 dimension (90.degree. pulse widths of 6.3
microseconds, and 33.5 microseconds were used for proton and
nitrogen, respectively) 48 transients were collected for each
increment, with a repetition delay of 1.2 seconds and acquisition
time of 0.124 seconds with GARP decoupling during acquisition. The
acquired data were processed with sine bell weighting and zero
filled to 8196.times.8196 points in F2 and F1 dimensions before
final transformation to produce the 2D correlation data.
[0364] The results are presented in FIGS. 15-17. FIG. 15 represents
the two-dimensional HSQC .sup.1H--.sup.15N NMR spectrum for
digested castor lot 5-83 in d6-DMSO. The y-axis represents .sup.15N
chemical shift scale (ppm), and the x-axis represents .sup.1H
chemical shift scale (ppm). The peaks within the spectrum represent
protonated nitrogen atoms from all of the fractions that were
present within the as-made digested castor (i.e., the
water-insoluble/water-dispersible polypeptide fractions plus the
water-soluble polypeptide fractions). The multiple peaks in region
B were observed to disappear upon removal of the water-soluble
fractions (see FIG. 16). This indicates that these protonated
nitrogens are specific to the water-soluble polypeptide fractions,
whereas at least a portion of the peaks in region A are specific to
the water-insoluble/water-dispersible fraction.
[0365] FIG. 16 represents the two-dimensional HSQC
.sup.1H--.sup.15N NMR spectrum for the
water-insoluble/water-dispersible polypeptide extract from digested
castor lot 5-83 in d6-DMSO. The y-axis represents .sup.15N chemical
shift scale (ppm), and the x-axis represents .sup.1H chemical shift
scale (ppm). The peaks within the spectrum represent protonated
nitrogen atoms from the water-insoluble/water-dispersible
polypeptide fraction. The peaks within Region B were observed to be
very weak in comparison to the analogous peaks within the digested
castor before extraction (see FIG. 15). Conversely, the remaining
peaks were predominantly from the protonated nitrogens in Region A.
This indicates that these particular protonated nitrogens are
specific to the water-insoluble polypeptide fractions. A magnified
view of this region is presented in FIG. 17.
[0366] As shown in FIG. 16, the peaks within the spectrum represent
protonated nitrogen atoms that are specific to the
water-insoluble/water-dispersible polypeptide fraction. Upon
expansion, the two "peaks" appear as narrow clusters that can be
readily defined by the .sup.15N and .sup.1H chemical shift
boundaries that define them: the .sup.15N boundaries for both
clusters occur at approximately 86.2 ppm and 87.3 ppm; and the
.sup.1H boundaries occur at approximately 7.14 and 7.29 ppm for the
first cluster; and at approximately 6.66 and 6.81 ppm for the
second cluster.
[0367] The results of these studies revealed that while the
water-soluble polypeptide fraction was composed of multiple types
of protonated nitrogen atoms (see FIG. 15), the
water-insoluble/water-dispersible fraction contained significantly
fewer types of protonated nitrogens, and was predominantly
characterized by the presence of two major proton-nitrogen cross
peak clusters (see FIG. 16). These differences, like those as seen
by solid state FTIR, illustrate that the chemical bonding
environments within the water-soluble polypeptide fraction are
distinctly different from those that exist within the
water-insoluble/water-dispersible fraction.
[0368] Together, the solid state FTIR and NMR data characterize the
water-insoluble/water-dispersible polypeptide fraction, where there
is a solid-state infrared amide-I absorption band between 1620-1632
cm.sup.-1; a solid-state infrared amide-II absorption band between
1514-1521 cm.sup.-1; and a solution-state pair of protonated
nitrogen clusters as determined by a .sup.1H--.sup.15N nuclear
magnetic resonance correlation technique. More specifically, when
the pair of protonated nitrogen clusters is observed by means of
NMR with deuterated d6-DMSO as the solvent using a two-dimensional
HSQC .sup.1H--.sup.15N NMR technique, the clusters are defined by
the .sup.15N and .sup.1H chemical shift boundaries that define
them: the .sup.15N boundaries for both clusters occur at
approximately 86.2 ppm and 87.3 ppm; and the .sup.1H boundaries
occur at approximately 7.14 and 7.29 ppm for the first cluster; and
at approximately 6.66 and 6.81 ppm for the second cluster.
[0369] Together, the solid state FTIR and NMR data also
characterize the water-soluble polypeptide fraction, where there is
a solid-state infrared amide-I absorption band between about
1633-1680 cm.sup.-1; a solid-state infrared amide-II absorption
band between 1522-1560 cm.sup.-1; two prominent 1.degree. amide
N--H stretch absorption bands centered at about 3200 cm.sup.-1, and
at about 3300 cm.sup.-1, as determined by solid state FTIR, and a
prominent cluster of protonated nitrogen nuclei defined by .sup.15N
chemical shift boundaries at about 94 ppm and at about 100 ppm, and
.sup.1H chemical shift boundaries at about 7.6 ppm and at about 8.1
ppm, as determined by solution state, two-dimensional
proton-nitrogen coupled NMR.
Example 4
Oil Dispersion Characteristics of Water-Soluble and
Water-Insoluble/Water-Dispersible Protein Fractions
[0370] A water-insoluble/water-dispersible polypeptide fraction and
a water-soluble polypeptide fraction were isolated from digested
castor (lot 5-108) based on procedures described in Example 1
(Procedure A). The digested castor can be prepared as follows:
castor meal protein is suspended in water at the ratio of about
1:10 w/w. Calcium chloride is added to an effective concentration
of about 10 mM, and the pH of the suspension adjusted to pH 9 by
the addition of 10N NaOH. The reaction is then heated to 55.degree.
C. while stirring. Next, Everlase 16L Type EX.RTM. (NOVOZYMES') is
added at the ratio of 10 g per kg of castor meal protein, and the
mixture is stirred at the same temperature for about 4 hours.
Finally, the resulting mixture is brought to a pH 3.5 with citric
acid and spray-dried to provide a powder.
[0371] The MALDI fragmentation molecular weight characteristics of
the isolated fractions are provided in Example 2. The solid state
FTIR spectroscopic absorption characteristics for the isolated
water-insoluble/water-dispersible polypeptide fraction conform with
those as described in FIGS. 4-6, 9, and 11-14 (amide-I absorption
range: 1620-1632 cm.sup.-1; amide-II absorption range: 1514-1521
cm.sup.-1). Solution state two-dimensional proton-nitrogen coupled
NMR on the isolated water-insoluble/water-dispersible polypeptide
fraction show two protonated nitrogen clusters enveloped by
.sup.15N chemical shift boundaries at approximately 86.2 ppm and
87.3 ppm; and with .sup.1H chemical shift boundaries at
approximately 7.14 and 7.29 ppm for the first cluster; and at
approximately 6.66 and 6.81 ppm for the second cluster. Solution
state two-dimensional proton-nitrogen coupled NMR on the isolated
water-soluble polypeptide fraction show a cluster of protonated
nitrogen nuclei defined by .sup.15N chemical shift boundaries at
about 94 ppm and at about 100 ppm, and .sup.1H chemical shift
boundaries at about 7.6 ppm and at about 8.1 ppm.
[0372] The water-insoluble/water-dispersible polypeptide fractions
with these spectral characteristics (unlike their water-soluble
counterparts) exhibit the unique ability to emulsify and stabilize
dispersions of oil in water and water in oil. This unique
oil-dispersing capability is observed with
water-insoluble/water-dispersible polypeptide compositions that are
extracted and isolated from multiple sources, including but not
limited to (1) whole meals or protein-isolates from either soy,
canola, or castor that are extracted of their water-soluble
polypeptide components at or near pH-neutral conditions; (2) whole
meals or protein-isolates from soy, canola or castor that are
subjected to base catalyzed hydrolysis followed by acid addition
and subsequent extraction of water-soluble polypeptide components;
(3) whole meals or protein-isolates from soy, canola or castor that
are subjected to acid catalyzed hydrolysis followed by base
addition and subsequent extraction of their water-soluble
polypeptide components; (4) whole meals or protein-isolates from
soy, castor, or canola that are subjected to combinations of base
catalyzed hydrolysis with enzyme digestion followed by acid
addition and subsequent extraction of water-soluble polypeptide
components.
[0373] It is understood that the stabilization of an oil-in-water
or water-in-oil emulsion/dispersion depends on several factors,
including but not limited to the presence or absence of a
stabilizing entity such as a surfactant or a dispersant; the nature
of the oil (i.e., its polarity, hydrophilicity, hydrophobicity,
solubility parameter, etc.); the nature of the surfactant or
dispersant (i.e., HLB value, charge characteristics, molecular
weight, water solubility, oil solubility, etc.); the ionic strength
of the water-phase; the presence or absence of additives and
impurities in either the oil or water phases; the concentration of
the oil (i.e., its weight percent in water); and the concentration
of the stabilizing entity. It is further understood that the
efficiency of a stabilizing entity (a "stabilizing entity" being a
dispersant, an emulsifier, a surfactant, or the
water-insoluble/water-dispersible polypeptide composition of the
present invention) is often judged according to its ability
stabilize an emulsion for some specified period of time (i.e., to
prevent the macroscopic phase separation of immiscible oil and
water components under shear or under static conditions).
[0374] In order to further demonstrate the generality of this
finding, several oil-in-water dispersions were prepared with a
water-insoluble/water-dispersible polypeptide composition that was
isolated from a digested castor protein. The
water-insoluble/water-dispersible polypeptide fraction was isolated
as a paste-like dispersion in water. The paste was diluted with
water to 16% solids, and separately to 14% solids. In the next
step, 3-gram aliquots of each paste were separately weighed into 15
mL plastic beakers. Next, aliquots of the oils shown in Table 3
were separately added to individual paste aliquots at a ratio of 1
part oil to 1 part solid water-insoluble/water-dispersible
polypeptide composition on a weight basis (20 mixtures in total).
The mixtures were stirred by hand with a spatula, and were observed
to form homogenous creams. The creams remained homogeneous with no
visible signs of macroscopic phase separation for prolonged periods
of time after mixing including periods ranging from 1 minute after
mixing, 5 minutes after mixing, 10 minutes after mixing, 15 minutes
after mixing, 30 minutes after mixing, 1 hour after mixing, and 2
hours after mixing. By contrast, the analogous water-soluble
extract from the digested castor was incapable of stabilizing
dispersions of the oils in water.
TABLE-US-00003 TABLE 3 Oil type Source PMDI Rubinate-M from
Huntsman Corporation Mineral oil Drakeol 35 from Penreco Soybean
oil RBD from ADM Processing Co. Motor oil Castrol Syntec, 5W-50
Castor oil Pale Pressed Castor Oil from Alnor Oil Company, Inc.
Dibutyl Phthalate 99% from Acros Epoxidized soybean oil From
Aldrich Caprylic triglyceride Neobee M-5 from Stepan Co. Eucalyptus
oil From Aromas Unlimited Tributyl o-acetylcitrate 98% from
Aldrich
[0375] Protein compositions not enriched for the
water-insoluble/water-dispersible fractions are unable to disperse
oils. For example, a 16% solids dispersion of soy protein isolate,
Lot 5-81, (Soy protein isolate SOLPRO 958.RTM. Solbar Industries
Ltd, POB 2230, Ashdod 77121, Israel; protein content approximately
90%) was prepared by adding 32 grams of soy protein isolate to 168
grams of water at a pH of approximately 4 to 6 (JM-570-1). Seven 10
gram aliquots of JM-570-1 were weighed into 20 mL disposable
beakers. A 10 gram aliquot contained 1.6 grams of soy protein
isolate and 8.4 grams of water. Seven different oils (namely, PMDI,
mineral oil, soybean oil, motor oil, castor oil, dibutyl phthalate
and epoxidized soybean oil) were added separately at a w/w ratio of
1 part oil to 1 part protein solids (1.6 grams oil was added to
each 10 gram aliquot). The mixtures were stirred by hand with a
spatula. None of the oils was observed to be dispersible in the 16%
solids dispersion of the soy protein isolate.
Example 5
Adhesive Composition Containing Canola Meal/Viscosity Analysis
[0376] Adhesive compositions containing ground canola meal were
prepared and subjected to viscosity analysis. The experimental
procedure and results of the analysis are described below.
[0377] General Experimental Procedure:
[0378] Adhesive compositions containing ground canola meal were
prepared. The identity and abundance of components in the adhesive
compositions are listed in Table 4. The ground canola meal had a
particle size in the range of 20 .mu.m to 70 .mu.m. The following
weight ratios were maintained as constants within each formula set:
meal/water, PMDI/meal, and urea/water. Each of the formulas was
qualitatively observed to form a stable dispersion upon mixing.
That is, neither visible settling nor macroscopic phase separation
of PMDI were observed over a 4.5 hour period of observation.
Viscosity measurements were taken to observe how urea and PMDI
affect viscosity and pot-life of the adhesive composition.
TABLE-US-00004 TABLE 4 WET FORMULA WEIGHT PERCENTAGES Ground Canola
Ratio of Ratio of Ratio of Meal Water Urea PMDI Meal/Water
PMDI/Meal Urea/Water (Weight (Weight (Weight (Weight by by by
Sample Percent) Percent) Percent) Percent) Weight Weight Weight
67-1A 31.250 68.750 0 0 0.45 0 0 67-1B 27.175 59.786 0 13.039 0.45
0.48 0 686-1A 25.000 55.000 20.000 0 0.45 0 0.36 686-1B 22.322
49.110 17.858 10.710 0.45 0.48 0.36 70-1A 24.799 75.201 0 0 0.33 0
0 70-1B 20.911 63.410 0 15.679 0.33 0.75 0 70-2A 20.911 63.410
15.679 0 0.33 0 0.75 70-2B 18.077 54.815 13.554 13.554 0.33 0.75
0.75
[0379] Rheological studies were performed using a Brookfield
Viscometer (model RVDVE) equipped with an RV spindle set. The wet
adhesives were filled to the 100 mL mark (near the top) of 100 mL
HDPE beakers for each measurement. The rotation speeds and
spindle-types were chosen so that a single measurement could be
used to cover the full range of viscosity values for the samples.
This set up permits the viscosity of samples containing PMDI to be
monitored as they cured over time. Samples without PMDI were
blended and evaluated within 4 hours of mixing. Samples with PMDI
were prepared by first blending all other ingredients together, and
then mixing PMDI for a period of 2 minutes. Viscosity measurements
were started within 5 minutes after mixing the PMDI. Table 5
provides the spindle numbers and rotation speeds (rpm) that were
used for each sample. Viscosity measurements were conducted at
approximately 25.degree. C.
TABLE-US-00005 TABLE 5 RV SPINDLE NUMBER AND ROTATION SPEED Spindle
Rotation Speed Upper Limit of Sample Number (rpm) Viscosity (cP)
67-1A 04 5 40,000 67-1B 07 5 800,000 686-1A 04 5 40,000 686-1B 06 5
200,000 70-1A 04 50 4,000 70-1B 04 50 4,000 70-2A 04 50 4,000 70-2B
04 50 4,000
[0380] Results:
[0381] Viscosity analysis of the adhesive compositions identified
different regions of rheological behavior. Further, the rheological
behavior of the adhesive depended on the components that formed the
adhesive composition. General regions of rheological behavior are
described in Table 6. FIGS. 20 and 21 show changes in rheological
behavior for the low viscosity set (samples 70-1A, 70-1B, 70-2A,
and 70-2B) and high viscosity formula set (samples 67-1A, 37-1B,
686-1A, and 686-1B). Table 7 provides comparative onset times and
region-specific relative viscosities for each sample.
TABLE-US-00006 TABLE 6 DEFINITIONS OF RHEOLOGICAL REGIONS OF
BEHAVIOR Region Rheological Observations Sample-Related
Observations A initial thinning period; occurs with all samples
fast reduction in viscosity with time B minimum viscosity period
relatively short in duration (minimal rate of change) C thinning
period; relatively occurs only in the absence of slow and steady
rate of PMDI viscosity reduction with time D thickening period;
viscosity occurs only in the presence of builds steadily with time
PMDI E unstable thickening period; occurs with the building of
viscosity builds and macroscopic structure due to fluctuates the
reaction of PMDI; structure can be mechanically broken, and mixture
exhibits analogous, vertically shifted viscosity profile upon
repeating measurements
TABLE-US-00007 TABLE 7 SUMMARY OF VISCOSITY TRENDS Region A
Relative Region B Region C Region D Region A Viscosity Relative
Region Relative Region D Relative Region E Duration Range Viscosity
C Onset Viscosity Onset Viscosity Onset Sample (min) (cP) (cP)
(min) Range (cP) (min) Range (cP) (min) 67-1A 19 38,000 to -- 19
11,000 to -- -- -- 11,000 7,500 67-1B 19 178,000 49,500 -- -- 21
49,000 to 49 to 49,000 300,000 686-1A 14 33,000 to 25,000 25 25,000
to -- -- -- 25,000 22,000 686-1B 11 26,000 to 25,000 -- -- 18
26,000 to 64 59,000 100,000 70-1A 20 530 to 370 -- -- -- -- -- 400
70-1B 20 900 to 530 -- -- 58 550 to 950 200 550 70-2A 20 600 to 550
-- -- -- -- -- 550 70-2B 23 950 to 750 -- -- 35 700 to 950 100
700
[0382] For samples containing PMDI, the viscosity of the sample was
observed to increase with time, independent whether urea was
present. In addition, samples with PMDI eventually reached a stage
where macroscopic structure and voids began to develop (Stage E).
This stage was accompanied by an increase in volume within the
sample container and subsequent viscosity fluctuations due to
random release and reformation of air pockets within the container
and within the vicinity of the rotating spindle. It was observed
that PMDI remained dispersed within the sample during Stage E; no
macroscopic phase separation was observed.
[0383] For samples 70-1B, 70-2B, and 686-1B, the macroscopic
structure could be broken by stirring, and the viscosity of the
samples decreased once the dispersion was broken. In addition, when
such samples were re-measured, they exhibited the same types of
rheological profiles--shear thinning followed by a short plateau,
and then followed by a viscosity building stage.
[0384] When defining the "pot-life" or "work time" for an adhesive,
the rheological behavior of the adhesive as a function of time
after mixing and the rheological restrictions imposed by
engineering processes are important. For example, in industrial
processes that make use of spray application methods (e.g.,
particle board and oriented strand board), it may be desirable to
use mixed adhesives before they reach Stage D as defined in Table
6. For various adhesives, this equates to a usage time window of up
to approximately 1 hour after mixing, independent of the presence
or absence of urea. On the other hand, for applications that
involve spreading or extruding, a build-up in viscosity may be
desirable, and hence it may be advantageous to use adhesives that
have already entered Stage D (this equates to a minimum adhesive
staging time of approximately 1 hour or more prior to use). In
applications where even thicker adhesives are desirable, it may be
advantageous for the adhesives to reach Stage D or E before
use.
[0385] Finally, in comparative experiments, mixtures containing
water, urea, and PMDI were mixed together in the absence of canola
meal at the same ratios as those used in the preparation of samples
686-1B and 70-2B. In the absence of canola meal, PMDI was observed
to macroscopically phase separate. Qualitative evidence for the
onset of a polymerization reaction was observed to occur within
approximately 15 minutes because the viscosity of the
phase-separated droplets began to build, and the material began to
stick to the surface of the glass container that was used for
mixing. However, formulations prepared with ground canola meal
facilitated the dispersion of PMDI, even when urea was present at
high levels within the formula. In one comparative case (67-1B vs.
686-1B), the presence of urea resulted in a lower overall viscosity
profile with a longer time prior to the onset of Stage E.
Example 6
Physical Characterization by Gravimetric Analysis, FTIR
Spectroscopy, and Oil-Dispersing Capacity of Ground Canola Meal,
Water-Insoluble/Water-Dispersible Protein Fraction Extracted from
Ground Canola Meal, and Water-Soluble Protein Fraction Extracted
from Ground Canola Meal
[0386] Ground canola meal, a water-insoluble/water-dispersible
protein fraction that was extracted from ground canola meal, and a
water-soluble protein fraction that was extracted from ground
canola meal were subjected to physical characterization by
gravimetric analysis, FTIR Spectroscopy, and ability to disperse
oil. Experimental procedures and results are provided below.
General Experimental Procedure:
[0387] Water-insoluble/water-dispersible protein fraction and
water-soluble protein fraction were isolated from ground canola
meal (the same meal used in Example 5) using the isolation method
described in Procedure F of Example 1. FTIR spectra were obtained
using solid state FTIR procedures outlined in Part-III of Example
1. Ability of the ground plant meal and ability of the individual
protein fractions (or a mixture of individual protein fractions) to
disperse PMDI in water was tested using procedures described in
Part-II of Example 1.
Gravimetric Solids Analysis:
[0388] After washing and supernatant decanting (3 cycles per the
protocol in Procedure F of Example 1), the resulting slurry of
water-insoluble/water-dispersible components (ca. 35% oven dried
solids by weight) was gravimetrically adjusted to achieve a
dispersion containing approximately 26% by weight solids (by adding
water as necessary). The overall yield of
water-insoluble/water-dispersible components was determined to be
approximately 55% by weight of the starting meal weight. Thus, the
ground canola meal contained (i) approximately 55% by weight of a
water-insoluble/water-dispersible protein fraction, and (ii)
approximately 45% by weight of a water-soluble fraction.
FTIR Spectroscopic Analysis:
[0389] To further characterize extracts from the ground canola
meal, solid state surface ATR FTIR experiments were performed on
the water-insoluble/water-dispersible protein fraction (this sample
was collected after the third wash cycle and was allowed to dry at
23.degree. C.), and on the water-soluble protein fraction (this
sample was collected from the clear supernatant after the third
wash cycle, and was allowed to dry at 23.degree. C. to yield a
transparent amber solid).
[0390] FIG. 22 shows the solid state FTIR spectra for the
water-insoluble/water-dispersible protein fraction isolated from
canola meal together with the water-soluble protein fraction where
the N--H stretching region has been expanded. This figure shows
that the predominant type of amide in the
water-insoluble/water-dispersible protein fraction is the secondary
main-chain amide as evidenced by the single, highly symmetric N--H
stretch band centered near 3275 cm.sup.-1. Although the
water-soluble protein fraction also contains this type of amide, it
contains a significantly higher amount of amine salts (as evidenced
by absorption over the region spanning from approximately 2670-2750
cm.sup.-1) and primary amides as evidenced by the presence of the
two primary N--H stretching bands at approximately 3200 cm.sup.-1
(symmetric) and at approximately 3330 cm.sup.-1 (asymmetric),
respectively. The spectra also reveal that both fractions contain
the characteristic spectroscopic signatures of proteins, even
though both fractions were isolated from raw meal (raw meal
contains other residual water-soluble and water-insoluble
components such as grain hulls, carbohydrates, sugars, and
oils).
[0391] Further, as shown in FIG. 23, the amide-I carbonyl
absorption band for the water-insoluble/water-dispersible protein
fraction was observed to appear as a predominant component at a
wavenumber of approximately 1634 cm.sup.-1, whereas that of the
water-soluble protein fraction was observed to appear as a
lower-intensity shoulder at approximately 1650 cm.sup.-1. As
discussed elsewhere, this feature distinguishes the
water-insoluble/water-dispersible protein fraction from the
water-soluble protein fraction, not only for isolated protein
fractions from castor proteins and soy proteins, but for
protein-containing fractions that are isolated directly from plant
meals like soy meal and canola meal. Moreover, the amide-II band
for the water-insoluble/water-dispersible protein fraction was
observed to appear as a broad band centered at approximately 1530
cm.sup.-1, whereas that of the water-soluble protein fraction was
observed to appear at approximately 1588 cm.sup.-1 together with a
weak shoulder at approximately 1550 cm.sup.-1.
Analysis of the Capacity of Ground Plant Meal and Isolated Protein
Fractions to Disperse Oil:
[0392] A dispersion of 26% (w/w) ground whole canola meal in water
was mixed with PMDI at a 1:1 w/w ratio of PMDI to canola meal
solids. The canola meal contained (i) approximately 55% by weight
water-insoluble/water-dispersible protein fraction and (ii)
approximately 45% by weight water-soluble protein fraction. The
dispersion of ground whole canola meal formed a stable dispersion,
which remained stable during a 1 hour period of observation with no
visual signs of phase separation.
[0393] An aliquot of 26% by weight solids dispersion of
water-insoluble/water-dispersible protein fraction (obtained from
canola plant meal by washing three times per the protocol described
in Procedure F of Example 1) was blended with PMDI at a w/w ratio
of 1 part PMDI to 1 part of the water-insoluble/water-dispersible
protein fraction (on a w/w PMDI/protein fraction-solids basis).
This resulting mixture formed a stable dispersion, which remained
stable during a 1 hour period of observation with no visible signs
of phase separation.
[0394] The water-soluble protein fraction (obtained by extracting
the canola meal and drying the supernatant after centrifuging) was
dissolved in water to yield a 26% (w/w) solids solution. When PMDI
was added to this solution (at a 1:1 weight ratio of PMDI to
water-soluble protein fraction solid material), the resulting
mixture was unstable, and it phase separated immediately after
mixing.
[0395] The results above illustrate that water-emulsified
PMDI-containing adhesive compositions can be prepared using
water-insoluble/water-dispersible protein fraction obtained from
ground plant meal. In addition, the results above illustrate that
water-emulsified PMDI-containing adhesive can be prepared using
ground plant meal compositions (that contain a sufficient amount of
water-insoluble/water-dispersible protein fraction; it is
understood that the ground plant meal composition also comprises
some water-soluble protein fraction). Although the water-soluble
protein fraction did not facilitate dispersion by itself in these
experiments, the dispersion of PMDI (and other oils) is understood
to be achievable so long as a sufficient amount of
water-insoluble/water-dispersible protein fraction is present in
the adhesive composition (or the ground plant meal used in the
adhesive composition).
[0396] To further illustrate the oil-dispersing ability of mixtures
containing a sufficient amount of water-insoluble/water-dispersible
protein fraction, the oil-dispersing characteristics of a meal
containing a large amount of water-insoluble/water-dispersible
protein fraction was compared to the oil-dispersing characteristics
of a commercially available soy-flour product containing a
relatively small amount of water-insoluble/water-dispersible
protein fraction. The commercially available soy-flour product used
was Prolia PDI-90, which is a de-fatted soy flour obtained from
Cargill).
[0397] As is understood, various commercially available derivatives
from plant meals are themselves solvent-extracted (e.g., soy
flour), which results in the removal of a substantial amount of the
water-insoluble/water-dispersible protein fraction. Such
compositions have not been found to facilitate dispersion of oil,
and, thus, are less desirable for use in making an adhesive. For
example, when PMDI was added to a 26% by weight solids dispersion
of soy flour in water at a 1/1 (w/w) of soy flour/PMDI, the PMDI
was observed to immediately phase separate from the mixture. By
contrast, soy meal was used under similar conditions in Example 1
produced a stable dispersion.
[0398] When soy flour was extracted using procedures discussed
herein, the isolated water-insoluble/water-dispersible protein
fraction was capable of dispersing PMDI in water. However, this
fraction was gravimetrically determined to comprise only
approximately 10% by weight of the starting soy flour mixture.
Thus, the component needed for oil dispersion was present in the
starting soy flour, but its effective concentration was too low for
the soy flour disperse PMDI in water. FTIR spectra for the isolated
water-insoluble/water-dispersible protein fraction and
water-soluble protein fraction extracted from soy flour are
provided in FIG. 24.
[0399] In contrast to soy flour, the
water-insoluble/water-dispersible protein fraction is a major
component in soy meal (at a level of approximately 50% by weight),
thus rendering the soy meal an effective dispersing agent for PMDI
in water. Upon isolation, the water-insoluble/water-dispersible
protein fraction extracted from both soy meal and soy flour (both
of which were able to facilitate the dispersion of PMDI in water)
were observed to contain similar spectral features as measured by
FTIR. Solid state FTIR of the water-insoluble/water-dispersible
protein fraction obtained from soy flour and soy meal are provided
in FIG. 25.
Example 7
Preparation of Nanocomposite Dispersions
[0400] It is difficult to maintain a stable dispersion when clay is
directly incorporated into neat PMDI. For example, if a clay like
Nanomer I-44P (i.e., mortmorillonite clay organically modified with
dimethyl, dialkyl(C.sub.14-C.sub.15) ammonium, supplied by Nanocor,
Inc.) is dispersed and partially exfoliated in mineral oil, the
resulting material does not remain dispersed in PMDI. Instead,
exfoliated clay in the mineral oil phase separates, agglomerates,
and/or reacts with the PMDI (owing to the amine functionality in
the I-44P) (see FIGS. 26 and 27). Similarly, it was not possible in
these experiments to disperse Nanomer I-44P directly into neat
PMDI. In addition to macroscopic phase separation, the active
ammonium surface treatment causes the PMDI to react and solidify
(see FIG. 28). Another type of clay, Nanomer PGV (a high purity
Na-montmorillonite), also failed to disperse when added to neat
PMDI (see FIG. 29).
[0401] As demonstrated by the above experiments and the results
shown in FIGS. 26-29, it is difficult to disperse commercially
available nanoclays (e.g., an intercalated montomorrillonite) into
neat PMDI without the unwanted side effects of macroscopic phase
separation and premature cure reactions. The protein component
described herein can reduce the quantity of undesired side effects,
such as macroscopic phase separation and premature cure reactions
associated with mixing commercially available nanoclays (e.g., an
intercalated montomorrillonite) into a reactive prepolymer, such as
PMDI.
[0402] The ability of canola meal to disperse a partially
exfoliated clay is demonstrated for multiple adhesive compositions,
which are described in Tables 8 through 11 below. These experiments
illustrate that the protein component, such as canola meal, can
facilitate (i) dispersion of PMDI, (ii) dispersion of intercalated
montmorillonite (either directly or with a separate oil phase), and
(iii) the dispersion of Na-montmorillonite in water. The protein
component minimizes macroscopic phase separation and the occurrence
of premature cure reactions associated with compositions of PMDI
and intercalalated montomorillonite that lack the protein
component. Further, protein adhesive compositions described in
Tables 8-11 below provide an effective binder for the manufacture
of wood composites and other articles.
TABLE-US-00008 TABLE 8 WET SLURRY COMPOSITION OF EXFOLIATED CLAY
ADHESIVES* Percent Percent Percent Percent Wet Slurry Percent
Canola Percent Percent Nanocor Mineral Nanocor Sample Composition
Water Meal Urea PMDI I-44P Oil PGV JM960-1 canola meal; 66.51%
27.17% 1.20% 0.00% 1.16% 2.72% 1.24% I-44P/PGV JM960-2 canola meal;
67.35% 27.51% 1.21% 0.00% 1.18% 2.75% 0.00% I-44P JM960-3 canola
meal; 69.20% 28.26% 1.25% 0.00% 0.00% 0.00% 1.29% PGV JM960-4
canola meal; 70.10% 28.63% 1.26% 0.00% 0.00% 0.00% 0.00%
*Percentages are weight percent of the adhesive composition.
Components are for Part B of a two-component adhesive
composition.
TABLE-US-00009 TABLE 9 DRY SOLIDS COMPOSITION OF ADHESIVES
CONTAINING PARTIALLY EXFOLIATED CLAY* Percent Percent Percent
Percent Dry Solids Percent Canola Percent Percent Nanocor Mineral
Nanocor sample Composition Water Meal Urea PMDI I-44P Oil PGV
JM960-1 canola meal; 0.00% 81.12% 3.58% 0.00% 3.48% 8.11% 3.71%
I-44P/PGV JM960-2 canola meal; 0.00% 84.25% 3.72% 0.00% 3.61% 8.42%
0.00% I-44P JM960-3 canol meal; 0.00% 91.76% 4.05% 0.00% 0.00%
0.00% 4.19% PGV JM960-4 canola meal 0.00% 95.78% 4.22% 0.00% 0.00%
0.00% 0.00% *Percentages are weight percent of the adhesive
composition. Components are for Part B of a two-component adhesive
composition.
TABLE-US-00010 TABLE 10 WET ADHESIVE COMPOSITION OF PARTIALLY
EXFOLIATED CLAY ADHESIVES* Wet Percent Percent Percent Percent
Adhesive Percent Canola Percent Percent Nanocor Mineral Nanocor
Sample Composition Water Meal Urea PMDI I-44P Oil PGV JM960-1
canola meal; 52.30% 21.36% 0.94% 21.36% 0.92% 2.14% 0.98% I-44P/PGV
JM960-2 canola meal; 52.82% 21.57% 0.95% 21.57% 0.92% 2.16% 0.00%
I-44P JM960-3 canola meal; 53.95% 22.04% 0.97% 22.04% 0.00% 0.00%
1.01% PGP JM960-4 canola meal 54.50% 22.26% 0.98% 22.26% 0.00%
0.00% 0.00% *Percentages are weight percent of the adhesive
composition. Components are for a mixture of Part A and Part B of a
two-component adhesive composition.
TABLE-US-00011 TABLE 11 DRY/CURED ADHESIVE COMPOSITION OF PARTIALLY
EXFOLIATED CLAY ADHESIVES* Dry Percent Percent Percent Percent
Adhesive Percent Canola Percent Percent Nanocor Mineral Nanocor
Sample Composition Water Meal Urea PMDI I-44P Oil PGV JM960-1
canola meal; 0.00% 44.79% 1.98% 44.79% 1.92% 4.48% 2.05% I-44P/PGV
JM960-2 canola meal; 0.00% 45.73% 2.02% 45.73% 1.96% 4.57% 0.00%
I-44P JM960-3 canola meal; 0.00% 47.85% 2.11% 47.85% 0.00% 0.00%
2.19% PGV JM960-4 canola meal 0.00% 48.92% 2.16% 48.92% 0.00% 0.00%
0.00% *Percentages are weight percent of the adhesive composition.
Components are for Part A and Part B of a two-component adhesive
composition.
[0403] The PMDI (polymeric methylenediphenyl di-isocyanate) for
this study was Rubinate-M, obtained from Huntsman Polyurethanes,
Woodlands, Tex. The canola meal was obtained from Viterra Canola
Processing Ste. Agathe, Manitoba, Canada. The meal was ground to a
particle size in the range of approximately 20 mm to 70 mm using a
Rotormill from International Process Equipment Company, Pennsauken,
N.J.
[0404] In the first step, the canola meal was added to water
together with urea to yield the protein-based dispersions
(precursors to the wet formulations described in Table 8). In a
separate step, a 70/30 mixture (w/w) of mineral oil/Nanomer I-44P
was prepared by mixing 30 grams of I-44P from Nanocor, Inc. into 70
grams of Drakeol mineral oil from Penreco, Inc. The samples were
mixed using a laboratory mixer and a dispersion-mixing blade. The
samples were mixed under high shear for 15 minutes, and were then
covered and placed in an ultrasonic bath for 1 hour to facilitate
further exfoliation. Partial exfoliation of the clay in the mineral
oil was evidenced by the formation of a gel-like mineral oil
amalgam. The concentrated amalgam was then added directly to the
water-based dispersions (at the prescribed levels as shown in Table
8).
[0405] The wet formulations described above (Table 8) were observed
to form stable dispersions with the mineral oil amalgam. Aliquots
of these dispersions were retained for subsequent observation. In
addition, a portion of these dispersions (devoid of PMDI) were
retained for the purpose of preparing comparative dry
nanocomposites without PMDI (compositions of Table 9). The aqueous
protein-based dispersions showed no visible signs of phase
separation over a 24 hour period of observation. In addition, aged
dispersions were observed to become more "gel-like" over time,
possibly due to continued exfoliation of intercalated aggregates
(continued exfoliation can lead to an increase in particulate
surface area which in turn can lead to an increase in viscosity
over time).
[0406] Aliquots of the dispersions were then mixed with PMDI to
yield the wet adhesive compositions of Table 10. No phase
separation was observed after the PMDI was mixed with the
dispersions (aliquots of the wet dispersions were visually observed
for approximately 1 hour). One aliquot of each mixed sample was
cured in a hot press at 205.degree. C. for 5 minutes. A second
aliquot of each sample was cured in a gravity oven at 110.degree.
C. for 24 hours. A third aliquot of each sample was cured in a
gravity oven at 40.degree. C. for 72 hours.
[0407] The PMDI samples containing Nanocor I-44P and Nanocor PGV
(i.e., the wet and cured 2-part mixtures described in Tables 10 and
11) were qualitatively observed to be different from the control
sample (i.e., JM-960-4, which did not contain clay that had
undergone exfoliation). Specifically, in the wet-adhesive state,
samples JM-960-1, JM-960-2, and JM-960-3 were higher in viscosity
and more gel-like. Moreover, in the dry-cured state, samples
JM-960-1, JM-960-2, and JM-960-3 were qualitatively more rigid
after curing than the control sample, JM-960-4.
[0408] In addition, the retained samples of the wet dispersions
containing exfoliated clay without PMDI (Table 8) continued to
build in viscosity and became more "gel-like" over a seven-day
period. No phase separation of the mineral oil carrier was
observed. Moreover, the oven-dried nanocomposites made without PMDI
(Table 9) were qualitatively tougher and stiffer than the
comparative oven dried sample made without the clay (JM-960-4 of
Table 9).
Example 8
Preparation of Particle Board Using Adhesive Compositions
Containing Nanoclays
[0409] Wet adhesives from Table 10 of Example 7 were used to
prepare particle board composites for this example. The composites
were prepared using the general procedure described below.
[0410] General Procedure:
[0411] Wet adhesive (100 g) was slowly added to 600 g of wood
particulate and the composition was mixed with a mechanical mixer.
A 9-inch.times.9-inch.times.9-inch wood forming box was centered on
a 12''.times.12''.times.1/8'' stainless steel plate, which was
covered with aluminum foil. The treated-wood was added slowly into
the forming box to try to get a uniform density of adhesive-coated
wood particles. After all the treated-wood was added, the
composition was compressed by hand with a
87/8''.times.87/8''.times.1/4'' plywood board, and the forming box
was carefully removed so that the treated particle board matte
would not be disturbed. The board was removed from the top of the
matte and a piece of aluminum foil was placed on top together with
another 12''.times.12''.times.1/8'' stainless steel plate. The
particleboard matte was pressed and cured to a thickness of 3/4''
using the following conditions: 117 psi pressure for 10 minutes at
a press platen temperature of 205.degree. C.
[0412] Composites were cut into 6 inch by 4 inch samples. Measured
densities of the boards are reported in Table 12.
TABLE-US-00012 TABLE 12 PARTICLEBOARD DENSITIES Sample Board
Density (g/cm.sup.3) Board Density (lb/ft.sup.3) JM-960-1 0.632
39.45 JM-960-2 0.630 39.33 JM-960-3 0.629 39.27 JM-960-4 0.620
38.71
[0413] Moisture resistance was evaluated by measuring the
percentage weight gain while the composites were soaked in water.
The weight of each 6''.times.4'' sample was measured prior to the
soaking experiment. The boards were placed vertically in a
17''.times.11''.times.1'' Teflon coated pan. One liter of distilled
water was slowly added to the pan. The percentage weight change of
each composite (soaked weight/initial weight.times.100%) was
measured as a function of soaking time (Table 13).
TABLE-US-00013 TABLE 13 PERCENT CHANGE IN SAMPLE WEIGHT AFTER
SOAKING IN WATER Percent Percent Percent Percent Weight Percent
Weight Weight Weight Change Weight Change Change Change After After
Change After After After Initial Soaking 3 Soaking 6 Soaking 12
Soaking 24 Soaking 48 Sample Weight Minutes Minutes Minutes Minutes
Minutes No. (grams) (grams) (grams) (grams) (grams) (grams)
JM-960-1 135.43 6.89% 17.28% 25.59% 47.78% 59.33% JM-960-2 137.84
6.75% 16.99% 24.81% 45.19% 55.59% JM-960-3 139.16 12.58% 21.05%
31.37% 50.47% 60.17% JM-960-4 137.43 13.61% 23.53% 34.63% 55.30%
65.95%
[0414] The data in Table 13 show that the nanocomposite boards
absorbed water more slowly than the composite without clay
(JM-960-4).
Example 9
Evaluation of Amalgams Prepared with Various Carriers
[0415] Adhesive formulations for this example were made using the
composition in JM-960-2 in Example 7 (Tables 8 through 11) with one
exception: the oil carrier for the 70/30 w/w mineral oil/I-44P
amalgam was changed to include other types of oils as listed in
Table 14. Separate 70/30 (w/w) blends of I-44P with each of the
carriers was prepared using the same procedures as described in
Example 7. The amalgams were then used to prepare separate
adhesives, and the adhesives were used to prepare particle board
composites using the procedures outlined in Example 8.
TABLE-US-00014 TABLE 14 OIL CARRIERS USED TO PREPARE 70/30 (W/W)
AMALGAMS OF OIL-CARRIER/I-44P Sample Carrier Supplier JM-994-1
Castor oil Pale Pressed Castor Oil from Alnor Oil Company, Inc.
JM-994-2 Soy oil RBD from ADM Processing Co. JM-994-3 Soy Methyl
Ester Columbus Vegetable Oils, Des Plaines, Illinois JM-994-4
(R)-(+)-Limonene Sigma-Aldrich Corp. JM-994-5 Canola Methyl Ester
Columbus Vegetable Oils, Des Plaines, Illinois TP-3 Tego
Protect-5000 .TM. silicone Evonik Tego Chemie GmbH TP-4 50/50 (w/w)
Tego Protect 5000 -- silicone/(R)-(+)-Limonene
[0416] Each of the amalgams was observed to form a viscous gel,
similar to that formed with mineral oil in Example 7. The amalgams
were readily dispersed when incorporated into the wet adhesive
compositions, and the resulting dispersions were observed to be
stable for at least 1 hour (before use). The resulting particle
board composites were observed to be tough and cohesively intact
upon removing them from the press.
Example 10
Preparation of Nano-Reinforced Particle Board Composites
[0417] Adhesive compositions were prepared with partially
exfoliated clay for the purpose of preparing particle board
composites. The amount of ingredients in the adhesive composition
were controlled for the purpose of delivering a constant level of
binder to the finished composites (total binder level=7.65% on a
wet wood basis). In samples lacking clay, the carrier vehicle was
added alone, and the percentage of all other adhesive components
was increased proportionally to account for the absence of the clay
(this was done to maintain a constant overall binder level). Thus,
in cases where clay was added to the binder, the total organic
content of the binder was lower than that of the comparable control
samples.
[0418] Samples with Nanomer I-44P clay were prepared by adding a
70/30 w/w amalgam of I-44P in an oil carrier (the amalgams were
prepared according to procedures outlined in Example 7) using one
of three carriers: Tego-Protect 5000 silicone; limonene; or a 50/50
w/w blend of Tego-Protect 5000 silicone with limonene. In cases
where PGV clay was used, the PGV was added directly to the
water-based dispersion. Formulations are provided in Tables 15
through 19. Particleboard composites were made according to the
procedures outlined in Example 8. The resulting particle board
composites were observed to be tough and cohesively intact upon
removing them from the press.
TABLE-US-00015 TABLE 15 WET SLURRY COMPOSITION OF ADHESIVES* Weight
Percent of Components Protein Meal Canola Nanocor Carrier Nanocor
Sample & Oil Carrier Water Meal Urea PMDI I-44P Oil PGV
JM-999-1 canola meal; 67.35% 27.51% 1.21% 0.00% 0.00% 2.75% 1.18%
PGV/limonene JM-999-2 canola meal; 67.35% 27.51% 1.21% 0.00% 1.18%
2.75% 0.00% I-44P/limonene JM-999-3 canola meal; 67.35% 27.51%
1.21% 0.00% 1.18% 2.75% 0.00% I-44P/Tego JM-999-4 canola meal;
67.35% 27.51% 1.21% 0.00% 1.18% 2.75% 0.00% I-44P/(50/50 w/w
Tego/Limonene) JM-999-5 canola meal; 67.35% 27.51% 1.21% 0.00%
0.00% 2.75% 1.18% PGV/(50/50 w/w Tego/Limonene) JM-999-6 control-1;
68.15% 27.84% 1.23% 0.00% 0.00% 2.78% 0.00% constant total binder
with Limonene JM-999-7 control-2; 68.15% 27.84% 1.23% 0.00% 0.00%
2.78% 0.00% constant total binder with Tego JM-999-8 control-3;
68.15% 27.84% 1.23% 0.00% 0.00% 2.78% 0.00% constant total binder
with 50/50 w/w/ Limonene & Tego *Percentages are weight percent
of the adhesive composition. Components are for Part B of a
two-component adhesive composition.
TABLE-US-00016 TABLE 16 PERCENTAGE OF DRY SOLIDS COMPOSITION OF
ADHESIVES* Weight Percent of Components Protein Meal Canola Nanocor
Carrier Nanocor Sample & Oil Carrier Water Meal Urea PMDI I-44P
Oil PGV JM- canola meal; 0.00% 84.25% 3.72% 0.00% 0.00% 8.42% 3.61%
999-1 PGV/limonene JM- canola meal; 0.00% 84.25% 3.72% 0.00% 3.61%
8.42% 0.00% 999-2 I-44P/limonene JM- canola meal; 0.00% 84.25%
3.72% 0.00% 3.61% 8.42% 0.00% 999-3 I-44P/Tego JM- canola meal;
0.00% 84.25% 3.72% 0.00% 3.61% 8.42% 0.00% 999-4 I-44P/(50/50 w/w
Tego/Limonene) JM- canola meal; 0.00% 84.25% 3.72% 0.00% 0.00%
8.42% 3.61% 999-5 PGV/(50/50 w/w Tego/Limonene) JM- control-1;
0.00% 87.41% 3.85% 0.00% 0.00% 0.00% 8.74% 999-6 constant total
binder with Limonene JM- control-2; 0.00% 87.41% 3.85% 0.00% 0.00%
0.00% 8.74% 999-7 constant total binder with Tego JM- control-3;
0.00% 87.41% 3.85% 0.00% 0.00% 0.00% 8.74% 999-8 constant total
binder with 50/50 w/w/ Limonene & Tego *Percentages are weight
percent of the adhesive composition. Components are for Part B of a
two-component adhesive composition.
TABLE-US-00017 TABLE 17 WET ADHESIVE COMPOSITIONS* Weight Percent
of Components Protein Meal Canola Nanocor Carrier Nanocor Sample
& Oil Carrier Water Meal Urea PMDI I-44P Oil PGV JM- canola
meal; 52.82% 21.57% 0.95% 21.57% 0.00% 2.16% 0.92% 999-1
PGV/limonene JM- canola meal; 52.82% 21.57% 0.95% 21.57% 0.92%
2.16% 0.00% 999-2 I-44P/limonene JM- canola meal; 52.82% 21.57%
0.95% 21.57% 0.92% 2.16% 0.00% 999-3 I-44P/Tego JM- canola meal;
52.82% 21.57% 0.95% 21.57% 0.92% 2.16% 0.00% 999-4 I-44P/(50/50 w/w
Tego/Limonene) JM- canola meal; 52.82% 21.57% 0.95% 21.57% 0.00%
2.16% 0.92% 999-5 PGV/(50/50 w/w Tego/Limonene) JM- control-1;
52.82% 21.57% 0.95% 22.50% 0.00% 2.16% 0.00% 999-6 constant total
binder with Limonene JM- control-2; 52.82% 21.57% 0.95% 22.50%
0.00% 2.16% 0.00% 999-7 constant total binder with Tego JM-
control-3; 52.82% 21.57% 0.95% 22.50% 0.00% 2.16% 0.00% 999-8
constant total binder with 50/50 w/w/ Limonene & Tego
*Percentages are weight percent of the adhesive composition.
Components are for Part A and Part B of a two-component adhesive
composition.
TABLE-US-00018 TABLE 18 DRY/CURED ADHESIVE COMPOSITIONS* Weight
Percent of Components Protein Meal Canola Nanocor Carrier Nanocor
Sample & Oil Carrier Water Meal Urea PMDI I-44P Oil PGV JM-
canola meal; 0.00% 45.73% 2.02% 45.73% 0.00% 4.57% 1.96% 999-1
PGV/limonene JM- canola meal; 0.00% 45.73% 2.02% 45.73% 1.96% 4.57%
0.00% 999-2 I-44P/limonene JM- canola meal; 0.00% 45.73% 2.02%
45.73% 1.96% 4.57% 0.00% 999-3 I-44P/Tego JM- canola meal; 0.00%
45.73% 2.02% 45.73% 1.96% 4.57% 0.00% 999-4 I-44P/(50/50 w/w
Tego/Limonene) JM- canola meal; 0.00% 45.73% 2.02% 45.73% 0.00%
4.57% 1.96% 999-5 PGV/(50/50 w/w Tego/Limonene) JM- control-1;
0.00% 45.73% 2.02% 47.69% 0.00% 4.57% 0.00% 999-6 constant total
binder with Limonene JM- control-2; 0.00% 45.73% 2.02% 47.69% 0.00%
4.57% 0.00% 999-7 constant total binder with Tego JM- control-3;
0.00% 45.73% 2.02% 47.69% 0.00% 4.57% 0.00% 999-8 constant total
binder with 50/50 w/w/ Limonene & Tego *Percentages are weight
percent of the adhesive composition. Components are for Part A and
Part B of a two-component adhesive composition.
TABLE-US-00019 TABLE 19 DRY/CURED PARTICLE BOARD COMPOSITION USING
THE WET ADHESIVES DESCRIBED IN TABLE 17* Percent Percent Percent
Percent Protein Meal Percent Canola Percent Percent Nanocor Carrier
Nanocor Sample & Oil Carrier Wood Meal Urea PMDI I-44P Oil PGV
JM-999-1 canola meal; 92.35% 3.50% 0.15% 3.50% 0.00% 0.35% 0.15%
PGV/limonene JM-999-2 canola meal; 92.35% 3.50% 0.15% 3.50% 0.15%
0.35% 0.00% I-44P/limonene JM-999-3 canola meal; 92.35% 3.50% 0.15%
3.50% 0.15% 0.35% 0.00% I-44P/Tego JM-999-4 canola meal; 92.35%
3.50% 0.15% 3.50% 0.15% 0.35% 0.00% I-44P/(50/50 w/w Tego/Limonene)
JM-999-5 canola meal; 92.35% 3.50% 0.15% 3.50% 0.00% 0.35% 0.15%
PGV/(50/50 w/w Tego/Limonene) JM-999-6 control-1; 92.35% 3.50%
0.15% 3.65% 0.00% 0.35% 0.00% constant total binder with Limonene
JM-999-7 control-2; 92.35% 3.50% 0.15% 3.65% 0.00% 0.35% 0.00%
constant total binder with Tego JM-999-8 control-3; 92.35% 3.50%
0.15% 3.65% 0.00% 0.35% 0.00% constant total binder with 50/50 w/w/
Limonene & Tego *Percentages are weight percent of the adhesive
composition. Components are for Part A and Part B of a
two-component adhesive composition. Percent total binder was
constant at 7.64% percent.
Example 11
Evaluation of Moisture Resistance of Nano-Reinforced Particle Board
Composites
[0419] Samples of particle board composites from Example 10 were
tested for moisture resistance using the methods outlined in
Example 8. Moisture resistance was evaluated by measuring the
percentage weight gain while the composites were soaked in water.
The weight of each 6''.times.4'' sample was measured prior to the
soaking experiment. The boards were placed vertically in a
17''.times.11''.times.1'' Teflon coated pan. One liter of distilled
water was slowly added to the pan. The percentage weight change of
each composite (soaked weight/initial weight.times.100%) was
measured as a function of soaking time (Tables 20 and 21).
TABLE-US-00020 TABLE 20 PERCENT CHANGE IN SAMPLE WEIGHT AFTER
SOAKING IN WATER Percent Percent Percent Percent Percent Weight
Weight Weight Weight Weight Change Change Change Change Change
After After After After After Initial Soaking 3 Soaking 6 Soaking
12 Soaking 24 Soaking 48 Sample Weight Minutes Minutes Minutes
Minutes Minutes Adhesive No. (grams) (grams) (grams) (grams)
(grams) (grams) Description JM-999-1 129.86 9.38% 22.4% 39.11%
60.75% 84.45% canola meal; PGV/limonene JM-999-2 125.15 5.81%
17.68% 33.97% 55.76% 73.07% canola meal; I-44P/limonene JM-999-6
126.25 9.77% 23.37% 41.07% 63.23% 77.39% constant total binder with
limonene
TABLE-US-00021 TABLE 21 PERCENT CHANGE IN SAMPLE WEIGHT AFTER
SOAKING IN WATER Percent Percent Percent Percent Percent Percent
Weight Weight Weight Weight Weight Weight Change Change Change
Change Change Change After After After After After After Initial
Soaking 24 Soaking Soaking 6 Soaking 12 Soaking Soaking Sample
Weight Minutes 3 Hours Hours Hours 24 Hours 48 Hours Adhesive No.
(grams) (grams) (grams) (grams) (grams) (grams) (grams) Description
JM-999-4 129.38 1.66% 2.65% 4.45% 7.11% 10.85% 14.83% canola meal;
I-44P/ (50/50 w/w Tego/Limonene) JM-999-5 131.2 1.73% 2.65% 4.61%
7.29% 11.02% 15.29% canola meal; PGV/(50/50 w/w Tego/Limonene)
JM-999-8 129.98 1.79% 2.62% 4.75% 7.50% 11.61% 16.17% constant
total binder with 50/50 w/w Limonene & Tego
[0420] Data in Tables 20 and 21 show that particle board composites
prepared with I-44P clay absorbed water more slowly than comparable
particle board composites made without I-44P clay (i.e., JM999-6
vs. JM999-2; and JM999-8 vs. JM999-4). Unlike the composites made
with I-44P clay, composites made with water-dispersible PGV &
limonene carrier performed no better than the comparable controls
(JM999-6 vs. JM999-1). However, those made with a 50/50 w/w blend
of limonene and Tego-Protect silicone performed better (JM999-8 vs.
JM999-5). The improvement in performance with I-44P clay is
remarkable when consideration is given to the fact that the clay
concentration in the cured composite was only 0.15% by weight
(1.96% by weight of the cured binder). In addition, the composites
without clay actually contained a higher fraction of the
water-resistant organic binder components (e.g., crosslinked PMDI)
than those made with clay. Thus, these experiments illustrate that
use of partially exfoliated clay in wood composites permits less
binder component to be used in manufacture of the particle board
composite without sacrificing moisture resistance.
Example 12
Preparation of Particleboard Composites Using Nanocomposite
Protein-Based Adhesive Compositions
[0421] Several nanocomposite adhesive compositions were made for
the purpose of preparing particleboard composites in accordance
with a Taguchi statistical design (4 factors with 3 levels per
factor). The experimental factors are given in Table 22 (factors
include: the weight percent PMDI in the binder, the weight percent
Nanomer I-44P nanoclay (i.e., mortmorillonite clay organically
modified with dimethyl, dialkyl(C.sub.14-C.sub.18) ammonium,
supplied by Nanocor, Inc.) in the binder, the type of oil carrier,
and the weight percent of binder in the dry-cured composite). The
wet adhesive compositions (provided in Table 23) were prepared
according to procedures outlined in Example 7 (using pre-mixed
amalgams of the carrier-oils with nanoclay). The dry-cured
compositions of the protein-based nanocomposite binders are
provided in Table 24. The resulting compositions of dry-cured
particleboard composites are provided in Table 25.
[0422] The Taguchi DOE compositions were prepared with a constant
level of urea (5% by weight of the dry-cured binder), and with a
constant level of oil carrier (11.67% by weight of the dry-cured
binder). Given that the amount of PMDI and amount I-44P were
incorporated at DOE-specified weight percentages, the balance of
the composition was made up with canola meal at varying weight
percentages of the dry-cured binder (Table 24). Because the canola
meal was pre-dispersed at a concentration of 27% w/w in water, the
weight percentage of water in the wet binder formulations varied
(Table 23). The silicone oil carrier used in the experiment was
Tego Protect-5000 functionalized silicone fluid from Evonik Tego
Chemie GmbH. Limonene used in the experiment was obtained from
Sigma-Aldrich Corporation (see Table 14 in Example 9). Each of the
adhesive compositions formed a stable dispersion (e.g., no settling
was observed within a 1 to 2 hour period after mixing).
[0423] The adhesive compositions were mixed with southern yellow
pine (SYP) wood furnish to yield semi-dry powder blends. The
resulting blends were then hot-pressed using procedures similar to
those outlined in Example 8. The mixtures were pressed separately
at both 150.degree. C. and at 200.degree. C. to yield particle
board composites (press time=10 minutes; pressure=186 psi). Each of
the dry-cured composites was observed to be rigid and cohesively
intact upon removal from the hot press. Then, the pressed samples
were cut into dimensions of approximately 9''.times.9''.times.1/8''
(23 cm.times.23 cm.times.0.32 cm) for subsequent testing.
TABLE-US-00022 TABLE 22 STATISTICALLY DESIGNED EXPERIMENT FOR
PARTICLEBOARD COMPOSITES COMPRISING NANOCOMPOSITE PROTEIN-BASED
ADHESIVES Weight Weight Weight Percent Percent Type Percent
Formulation PMDI I-44P of Oil Binder in No. in Binder in Binder
Carrier Cured Composite 1 37.0% 0.0% Silicone 13.34% 2 37.0% 2.5%
50/50 (w/w) 18.67% Silicone/ Limonene 3 37.0% 5.0% Limonene 24.00%
4 43.5% 0.0% 50/50 (w/w) 24.00% Silicone/ Limonene 5 43.5% 2.5%
Limonene 13.34% 6 43.5% 5.0% Silicone 18.67% 7 50.0% 0.0% Limonene
18.67% 8 50.0% 2.5% Silicone 24.00% 9 50.0% 5.0% 50/50 (w/w) 13.34%
Silicone/ Limonene Comparative 100.0% 0.0% none 13.34% PMDI
Sample
TABLE-US-00023 TABLE 23 WET SLURRY ADHESIVE COMPOSITIONS* Weight
Percent Component Canola Nanacor Carrier Sample No. Oil Carrier
Water Meal Urea PMDI I-44P Oil 1 (JM9121-1) silicone 55.61% 20.57%
2.22% 16.42% 0.00% 5.18% 2 (JM9121-2) silicone/limonene 54.24%
20.06% 2.29% 16.93% 1.14% 5.34% 3 (JM9121-3) limonene 52.78% 19.52%
2.36% 17.47% 2.36% 5.51% 4 (JM9121-4) silicone/limonene 51.85%
19.18% 2.41% 20.94% 0.00% 5.62% 5 (JM9121-5) limonene 50.23% 18.58%
2.49% 21.65% 1.24% 5.81% 6 (JM9121-6) silicone 48.50% 17.94% 2.57%
22.40% 2.57% 6.01% 7 (JM9121-7) limonene 47.40% 17.53% 2.63% 26.30%
0.00% 6.14% 8 (JM9121-8) silicone 45.46% 16.82% 2.73% 27.27% 1.36%
6.36% 9 (JM9121-9) silicone/limonene 43.38% 16.04% 2.83% 28.31%
2.83% 6.61% 10 (JM9121-10) none 0% 0% 0% 100% 0% 0% *Percentages
are weight percent of the wet adhesive composition. Components are
for Parts A + B of a two-component adhesive composition.
TABLE-US-00024 TABLE 24 DRY/CURED ADHESIVE COMPOSITIONS* Weight
Percent of Components in Dry/Cured Adhesive Composition Canola
Nanocor Carrier Sample No. Oil Carrier Water Meal Urea PMDI I-44P
Oil 1 (JM9121-1) silicone 0.00% 46.33% 5.00% 37.00% 0.00% 11.67% 2
(JM9121-2) silicone/limonene 0.00% 43.83% 5.00% 37.00% 2.50% 11.67%
3 (JM9121-3) limonene 0.00% 41.33% 5.00% 37.00% 5.00% 11.67% 4
(JM9121-4) silicone/limonene 0.00% 39.83% 5.00% 43.50% 0.00% 11.67%
5 (JM9121-5) limonene 0.00% 37.33% 5.00% 43.50% 2.50% 11.67% 6
(JM9121-6) silicone 0.00% 34.83% 5.00% 43.50% 5.00% 11.67% 7
(JM9121-7) limonene 0.00% 33.33% 5.00% 50.00% 0.00% 11.67% 8
(JM9121-8) silicone 0.00% 30.83% 5.00% 50.00% 2.50% 11.67% 9
(JM9121-9) silicone/limonene 0.00% 28.33% 5.00% 50.00% 5.00% 11.67%
10 (JM9121-10) none 0.00% 0.00% 0.00% 100.00% 0.00% 0.00%
*Percentages are weight percent of the dry/cured adhesive
composition. Components are for Parts A + B of a two-component
adhesive composition.
TABLE-US-00025 TABLE 25 DRY/CURED PARTICLE BOARD COMPOSITIONS USING
THE WET ADHESIVES DESCRIBED IN TABLE 23* Percent Percent Percent
Protein Meal Percent Canola Percent Percent Nanocor Carrier Sample
& Oil Carrier Wood Meal Urea PMDI I-44P Oil 1 (JM9121-1)
silicone 86.66% 6.18% 0.67% 4.93% 0.00% 1.56% 2 (JM9121-2)
silicone/limonene 81.05% 8.31% 0.95% 7.01% 0.47% 2.21% 3 (JM9121-3)
limonene 76.00% 9.92% 1.20% 8.88% 1.20% 2.80% 4 (JM9121-4)
silicone/limonene 76.00% 9.56% 1.20% 10.44% 0.00% 2.80% 5
(JM9121-5) limonene 86.67% 4.98% 0.67% 5.80% 0.33% 1.55% 6
(JM9121-6) silicone 81.06% 6.60% 0.95% 8.24% 0.95% 2.21% 7
(JM9121-7) limonene 81.06% 6.31% 0.95% 9.47% 0.00% 2.21% 8
(JM9121-8) silicone 75.99% 7.40% 1.20% 12.00% 0.60% 2.80% 9
(JM9121-9) silicone/limonene 86.66% 3.78% 0.67% 6.67% 0.67% 1.56%
10 (JM9121-10) none 86.66% 0.00% 0.00% 13.34% 0.00% 0.00%
*Percentages are weight percent of the cured composite composition.
Components are for Parts A + B of a two-component adhesive
composition. Percent total binder was varied as a controlled factor
in the designed experiment.
Example 13
Evaluation of Moisture Resistance of Particleboard Prepared with
Nanocomposite Binder
[0424] Particleboard samples from Example 12 were cut and tested
for relative moisture resistance (via water-soak testing procedures
similar to those described in Example 11). The relative glass
transition temperature (Tg) was determined for particleboard
samples using dynamic mechanical analysis (DMA).
Water-Soak Procedure
[0425] Sample specimens were cut into dimensions of approximately
53 mm.times.21 mm.times.3 mm for water-soak testing. Samples were
weighed and the dimensions were measured prior to soaking. The
samples were placed into a 7.5''.times.9.5''.times.3.0'' (19
cm.times.24 cm.times.8 cm) polyethylene pan, which contained one
liter of water at 23.degree. C. The samples were kept submerged in
the water with a weighted aluminum screen. Sample weights were
measured as a function of soak time by taking the samples out of
the water, blotting them dry, and weighing. Then, the samples were
returned to the water after each measurement for continued soaking,
and for subsequent measurements as a function of soak time (over a
24 to 48 hour period).
[0426] The rate of water uptake was observed to be non-linear,
following a power-law dependence, where the diffusion rate was
observed to decrease as a function of time due to the viscoelastic
response of the cross-linked composite. All data were fit to the
following equation: percent water uptake=D(t).sup.n; where the
percent water uptake=100*(wet weight-dry weight)/dry weight; and
where the diffusion coefficients (D) and the power-law orders (n)
were determined by fitting the data to the power law equation. The
resulting diffusion coefficients (D) and the power-law orders (n)
(given in Table 26 together with goodness of fit correlations) were
then treated as measured responses for the purposes of modeling and
testing the effects of the controlled experimental factors on
diffusion.
DMTA Procedure
[0427] The viscoelastic properties of composites (that were pressed
at 200.degree. C.) were determined with a Rheometric Scientific
DMTA IV dynamic mechanical analyzer (DMTA). The experiments were
conducted in dual cantilever mode with sample dimensions of
approximately 25 mm.times.5 mm.times.2 mm at a fixed frequency of
50 Hz. The strain amplitude was fixed at 0.05 to be within the
domain of linear viscoelasticity. The samples were subjected to the
following thermal profile: step-1) heat from 25.degree. C. to
105.degree. C. at a heating rate of 10.degree. C./min; step-2) hold
isothermally for 15 min. at 105.degree. C.; step-3) cool from
105.degree. C. to -60.degree. C. at a 10.degree. C./minute cooling
rate; step-4) hold isothermally for 5 minutes at -60.degree. C.;
and step-5) heat from -60 to 250.degree. C. at a heating rate of
5.degree. C./minute while collecting data. The relative glass
transition temperature (Tg) for each composite was determined from
the temperature of the Tan-delta peak maximum between approximately
-25.degree. C. and 50.degree. C. at 50 Hz (Table 27). The Tg values
were then treated as measured responses for the purposes of
modeling and testing the effects of the controlled experimental
factors on the viscoelastic behavior of the composites.
Results from Statistical Modeling
[0428] A statistical modeling program (Design Ease 7.1.6 by
Stat-Ease, Inc., Minneapolis, Minn.) was used to model the measured
responses for the composites (D, n, Tg) as a function of the
primary factors and interactions listed in Table 28. Factors and
interactions with p-values of less than 0.05 were considered to be
statistically significant at the 95% confidence level, and were
subsequently used to construct response models. The high
correlation coefficients and low p-values for the resulting
response models are indicative of their reliability. In order to
illustrate this, the models were used to predict the
moisture-diffusion response curve for DOE Sample No. 9 pressed at
200.degree. C. (see Table 22 in Example 12). Sample No. 9 was
defined as follows: the composite contained 13.34 weight percent of
binder; the binder contained 5 weight percent Nanomer I-44P and 50
weight percent PMDI; and the oil mixed with the Nanomer I-44P was a
mixture of silicone and limonene. The actual measured parameters
for D and n were 14.7 (wt. %/hr.) and 0.415, respectively (see
Table 26), and the model-calculated values for D and n were
determined to be 14.7 and 0.456, respectively. The measured and
calculated responses for D and n were then used to construct
water-diffusion curves for a side-by-side comparison with Sample
No. 10 (neat PMDI).
[0429] As illustrated by the results in FIG. 30, the measured
response was closely approximated by the modeled response. In
addition, the protein-containing composite exhibited significantly
better moisture resistance than the composite made with neat PMDI.
It is noted that although these two composites were made with
equivalent levels of binder (13.34 weight percent), DOE Sample No.
9 contained only one half the amount of PMDI. Thus, the results
depicted in FIG. 30 illustrate the reliability of the models, as
well as the improved moisture-resistance afforded by the combined
use of protein-meal with exfoliated montmorillonite.
[0430] In order to demonstrate the impact of montmorillonite
itself, another type of comparison was made. Diffusion coefficients
and n-values were calculated for formulations made with and without
nanoclay using the following constraints: the composite contained
13.34 weight percent of binder; the binder contained either no
Nanomer I-44P or 5 weight percent Nanomer I-44P; the binder
contained 37 weight percent PMDI; and the oil mixed with the Naomer
I-44P was silicone and limonene. FIG. 31 shows water-diffusion
curves for these compositions, along with a water-diffusion curve
for Sample No. 10 (containing 13.34 weight percent neat PMDI).
These results illustrate that the moisture resistance of the
protein-containing composite was equivalent to that of the neat
PMDI composite, even though the amount of PMDI was only 37% of that
which was used in the neat PMDI case. Moreover, the addition of 5
percent by weight montmorillonite to the binder resulted in
significantly improved moisture resistance. This result is
surprising since the amount of Nanomer I-44P in the binder is less
than 0.7 percent by weight in the dry-cured wood composite.
[0431] FIGS. 32-35 illustrate the effects of controlled factors on
measured responses (error bars represent least significant
differences). For example, as shown in FIG. 32, the diffusion rate
of water was observed to decrease significantly (p=0.0146) as the
percentage of montmorillonite was increased in composites pressed
at 150.degree. C. As shown in FIG. 33 for composites pressed at
200.degree. C., the diffusion rate of water was observed to
decrease as the percentage of PMDI was increased (in the absence of
montmorillonite). However, in the presence of montmorillonite, the
diffusion rate remained constant, i.e., the diffusion rate was
independent of the PMDI concentration. Moreover, when PMDI was used
in combination with montmorillonite, the moisture resistance
significantly improved at low quantities of PMDI (p=0.0083).
[0432] As shown in FIG. 34B for composites pressed at 200.degree.
C. (with the following constraints: the composite contained 13.34
weight percent binder; the bonder contained 41.5 weight percent
PMDI; and the oil used was a mixture of silicone and limonene), the
apparent glass transition temperature of the composite was observed
to significantly increase with increasing montmorillonite
concentration in the binder. The increase in Tg with increasing
amounts of montmorillonite was accompanied by improved moisture
resistance (decreased water diffusion rates).
[0433] As shown in FIG. 35 for composites pressed at 200.degree.
C., the apparent glass transition temperature was observed to
increase with increasing PMDI concentration in the binder, but only
in the presence of the montmorillonite. The increase in Tg with
increasing amount of montmorillonite was consistent with the
observations of improved moisture resistance (decreased water
diffusion rates). See FIG. 34A.
[0434] In conclusion, water-insoluble/dispersible proteins in
ground plant meal have been found to facilitate water-based
dispersion and processing of pre-exfoliated montmorillonite/oil
amalgams to yield protein-based nanocomposite adhesives.
Protein-based nano-scale dispersions can be successfully
co-dispersed with PMDI to yield stable two-part crosslinkable
adhesives. By contrast, mixtures of neat PMDI with nanoparticles
and/or with pre-exfoliated oil amalgams tend to undergo premature
reactions and macroscopic phase-separation.
[0435] Also, wood composites made with protein-based nanocomposite
adhesives exhibited significantly better moisture resistance
characteristics than analogous composites made with neat PMDI. As
shown by the data analyses, this capability is facilitated by the
presence of exfoliated montmorillonite, where the exfoliation,
dispersion, and molecular-level associations of nanoparticulates
are assisted by water-insoluble/dispersible protein components
within the formulations.
TABLE-US-00026 TABLE 26 DIFFUSION COEFFICIENTS (D) AND POWER-LAW
ORDER (N) FOR WATER UPTAKE DIFFUSION INTO PARTICLE BOARD COMPOSITES
AS DESCRIBED IN TABLE 25* Water Water Diffusion Diffusion
Coefficient Power-Law Correlation Coefficient Power-Law (D) for
Dependence Coefficient (D) for Dependence Correlation Samples (n)
for (R) for Samples (n) for Coefficient (R) Pressed at Samples
Samples Pressed at Samples for Samples Sample 150.degree. C.
Pressed at Pressed at 200.degree. C. Pressed at Pressed at No. (wt.
%/hr) 150.degree. C. 150.degree. C. (wt. %/hr) 200.degree. C.
200.degree. C. 1 27.674 0.37924 0.97099 23.325 0.47523 0.96600 2
20.158 0.36436 0.99452 17.778 0.47435 0.99000 3 44.089 0.15518
0.92428 39.846 0.21814 0.90000 4 12.804 0.41481 0.99172 14.668
0.47994 0.99100 5 56.298 0.21237 0.92492 46.031 0.26603 0.93000 6
14.903 0.40309 0.99813 13.376 0.48966 0.99800 7 55.857 0.16329
0.84405 28.081 0.36457 0.95600 8 10.537 0.43293 0.99792 10.472
0.46910 0.99800 9 18.427 0.39437 0.99953 14.712 0.41533 0.99800
PMDI 21.963 0.34476 0.9988 24.853 0.42061 0.98221 *From the best
fit of percent water uptake vs. time using the equation D(t).sup.n
with D and n as adjustable parameters.
TABLE-US-00027 TABLE 27 TEMPERATURE OF TAN-DELTA MAXIMUM FOR
PARTICLE BOARD COMPOSITES AS DESCRIBED IN TABLE 25* Tan-delta
Temperature Maxima for Samples Pressed at 200.degree. C. Sample No.
(degrees C.) 1 17.77 2 17.03 3 15.77 4 16.23 5 28.13 6 28.14 7
12.65 8 28.68 9 33.27 PMDI 17.77 *From dynamic mechanical analysis
(DMA) of particle board composites cured at 200.degree. C.,
measured at 50 Hz and taken from the tan-delta peak maxima between
-25.degree. C. and 50.degree. C.
TABLE-US-00028 TABLE 28 SUMMARY OF RESULTS FOR ANALYSIS OF VARIANCE
(ANOVA) IN TERMS OF THE DESIGNED EXPERIMENTAL FACTORS (USING THE
MEAN RESPONSES AS LISTED IN TABLES 26 AND 27)* Factor-B Factor-D
Correlation Factor-A Percent Factor-C Percent Coefficient Percent
I-44P .TM. Oil Binder in Interaction (R.sup.2) and p- PMDI in in
Carrier Cured Term & value for Best- Response Binder Binder
Type Composite Significance Fit Model D (150.degree. C. NS VS (-)
VS VS (-) None 0.99 & 0.0003 Sample Set) (1 = 2 < 3) (VS) n
(150.degree. C. NS NS VS NS None 0.95 & 0.0001 Sample Set) (1 =
2 > 3) (VS) D (200.degree. C. VS (-) NS (-) VS NS A .times. B,
VS (+) 0.99 & .002 Sample Set) (1 = 2 < 3) (VS) n
(200.degree. C. NS NS VS NS None 0.83 & 0.005 Sample Set) (1 =
2 > 3) (VS) Tan-delta T- VS (+) VS (+) NS NS A .times. B, VS
0.93 & 0.007 max (200.degree. C. (+) (VS) Sample Set) *The
symbol "VS" indicates very significant at the 95% confidence level
with p < 0.05; The symbol "S" indicates significant at the 90%
confidence level with p < 0.1; and the symbol "NS" indicates not
significant. A designation of "+" indicates that the response
increased as the level of a given factor or interaction was
increased. Conversely, a designation of "-" indicates that the
response decreased as the level of a given factor or interaction
was increased. The oil carrier types include: Type-1 = silicone;
Type-2 = 50/50 (w/w) silicone/limonene; Type-3 = limonene.
Example 14
Preparation of Particle Board Composite Containing a Fire
Retardant
[0436] The first retardant Colemanite
(CaB.sub.3O.sub.4(OH).sub.3--H.sub.2O) was dispersed in an adhesive
composition containing canola meal, PMDI, and water. The adhesive
composition was applied to southern yellow pin particleboard
furnish to form a particle board composite. This example
demonstrates the surprising result that the ground canola meal
adhesive composition can be used to disperse Colemanite, whereas
Colemanite cannot be dispersed into neat PMDI.
[0437] The ability to incorporate Colemanite into the adhesive
composition is particularly beneficial for preparing fire retardant
wood composite materials because Colemanite (a fine, dense, dry
powder) by itself is not easily dispersed onto wood in its dry form
because the Colemanite does not stick to the wood particle surfaces
in quantities sufficient to impart fire retardant properties to the
wood composite. The adhesive composition described herein (which
incorporates Colemanite) solves this problem, thereby permitting
preparation of wood composite materials containing an amount of
Colemanite sufficient to impart fire-retardant properties to the
wood composite.
Preparation of Adhesive Composition
[0438] The two adhesive compositions shown in Table 29 below were
prepared by mixing the named ingredients in the amounts specified
in the table.
TABLE-US-00029 TABLE 29 WET ADHESIVE COMPOSITIONS Weight Weight
Weight Weight Water Canola Meal Colemanite PMDI Sample No. (Grams)
(Grams) (Grams) (Grams) JM-9157-6 0 0 0.00 10.53 JM-9157-10 74
12.31 40.29 13.19
Preparation of Particle Board Composites
[0439] Wet adhesive (as indicated in Table 29) was added slowly to
200 g of southern yellow pine particleboard furnish having a
moisture content of 6.0%. The composition (wood+adhesive) was mixed
with a mechanical mixer. A 9-inch.times.9-inch.times.9-inch wood
forming box was centered on a 12''.times.12''.times.1/8'' stainless
steel plate, which was covered with aluminum foil. The treated wood
was added slowly into the forming box to achieve a uniform density
of adhesive-coated wood particles. After all the treated-wood was
added, the composition was compressed by hand with an
87/8''.times.87/8''.times.1/4'' plywood board, and the forming box
was carefully removed so that the treated particleboard matte would
not be disturbed. The board was removed from the top of the matte
and a piece of aluminum foil was placed on top together with
another 12''.times.12''.times.1/8'' stainless steel plate. The
particleboard matte was pressed and cured to a thickness of 1/4''
using the following conditions: 117 psi pressure for 10 minutes at
a press platen temperature of 205.degree. C. The samples were
allowed to equilibrate in the lab for 2 weeks to constant moisture
content of 12% prior to burn testing. The composition of the dried
adhesive in the particle board composite is shown in Table 30.
TABLE-US-00030 TABLE 30 COMPOSITION OF DRIED ADHESIVES Weight
Percent Weight Percent Weight Percent Canola Meal in Colemanite in
PMDI in the Oven Dry the Oven Dry Oven Dry Sample No. Composite
Composite Composite JM-9157-6 0% 0% 5.00% JM-9157-10 4.63% 15.15%
5.00%
[0440] Three samples measuring 3 inches by 2 inches were cut from
each composite board. The samples were labeled and weighed prior to
burn testing. Each sample was clamped by one edge in a brick
chamber for burn studies as illustrated in FIGS. 36A, 36B, &
36C.
[0441] The heat source for the burn was a BERNZOMATIC Butane Micro
Torch. The torch nozzle distance was placed 5 cm from the sample.
The torch setting was set to high which was reported to be
3100.degree. F. (1704.degree. C.) in the Bernzomatic literature.
The torch was lit and placed in front of the sample for a defined
period of time, as shown below.
[0442] The samples were weighed before and after burning. Three
burn tests were conducted: (1) one set of samples was burned for 30
seconds; (2) a second set of samples was burned for 60 seconds; and
(3) a third set of samples was burned for 120 seconds. The flame
was extinguished by blowing out the flame if sustained burning was
observed. FIG. 37 depicts a sample being subjected to a burn
test.
[0443] After the samples were cooled they were re-weighed to
determine weight loss. The percent weight loss and observations can
be seen in Table 31. The front and back surfaces of the burned
samples are depicted in FIG. 38.
TABLE-US-00031 TABLE 31 RESULTS OF BURN TESTING Percent Burn Tim
Weight Sample No. (seconds) Loss Observations JM-9157-6-A 30 7.46%
Sustained flame after burn JM-9157-10-A 30 2.75% Flame not
sustained after burn JM-9157-6-B 60 17.65% Sustained flame after
burn, continued smoldering for several minutes, char on back of
sample and sample loss JM-9157-10-B 60 6.75% Flame not sustained
after burn, no char on back of sample JM-9157-6-C 120 31.1%
Sustained flame after burn, continued smoldering for several
minutes, char on back of sample and sample loss JM-9157-10-C 120
8.47% Flame not sustained after burn, no char on back of sample
[0444] As illustrated by the data in Table 31 and the results in
FIG. 38, samples containing Colemanite did not lose as much weight
when burned and did not char to the same extent as control samples
containing no Colemanite. The canola meal/PMDI adhesive permits
incorporation of Colemanite and keeps the Colemanite on the surface
of the wood particles imparting fire resistance properties to the
wood composite.
INCORPORATION BY REFERENCE
[0445] The entire disclosure of each of the patent and scientific
documents referred to herein is incorporated by reference for all
purposes.
EQUIVALENTS
[0446] The invention may be embodied in other specific forms
without departing from the spirit or essential characteristics
thereof. The foregoing embodiments are therefore to be considered
in all respects illustrative rather than limiting on the invention
described herein. Scope of the invention is thus indicated by the
appended claims rather than by the foregoing description, and all
changes that come within the meaning and range of equivalency of
the claims are intended to be embraced therein.
* * * * *