U.S. patent application number 13/486555 was filed with the patent office on 2012-12-06 for curable biopolymer nanoparticle latex binder for mineral, natural organic, or synthetic fiber products and non-woven mats.
Invention is credited to Steven Bloembergen, Alexander Tseitlin, David Van Alstyne.
Application Number | 20120309246 13/486555 |
Document ID | / |
Family ID | 47258253 |
Filed Date | 2012-12-06 |
United States Patent
Application |
20120309246 |
Kind Code |
A1 |
Tseitlin; Alexander ; et
al. |
December 6, 2012 |
CURABLE BIOPOLYMER NANOPARTICLE LATEX BINDER FOR MINERAL, NATURAL
ORGANIC, OR SYNTHETIC FIBER PRODUCTS AND NON-WOVEN MATS
Abstract
A curable aqueous binder composition includes a dispersion of
biopolymer particles, optionally with and an inter-particle
crosslinking agent, for use in the formation of composite materials
such as mineral, natural organic, or synthetic fiber products,
including mineral fiber insulation, non-woven mats, fiberglass
insulation and related glass fiber products, and wood based
products, and construction materials. In an application of the
curable aqueous composition to making fiberglass insulation, the
composition may be blended with a second resin which may be a
non-formaldehyde resin. In an application of the composition to
making fiberglass roofing shingles, the biopolymer particles may be
mixed into a formaldehyde based resin during or after the
polymerization of the resin.
Inventors: |
Tseitlin; Alexander; (Halton
Hills, CA) ; Van Alstyne; David; (Burlington, CA)
; Bloembergen; Steven; (Okemos, MI) |
Family ID: |
47258253 |
Appl. No.: |
13/486555 |
Filed: |
June 1, 2012 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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61493266 |
Jun 3, 2011 |
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Current U.S.
Class: |
442/180 ;
106/162.51; 106/212.1; 524/47; 524/734; 977/773 |
Current CPC
Class: |
C08L 3/04 20130101; C08L
23/00 20130101; C08K 5/0025 20130101; C08L 67/00 20130101; C08L
89/00 20130101; B27N 3/04 20130101; C09J 161/24 20130101; C08L
33/08 20130101; C08L 2205/16 20130101; C08L 2205/18 20130101; C08L
77/02 20130101; C08L 97/02 20130101; C08J 2303/02 20130101; B29C
39/003 20130101; C08L 77/00 20130101; C08J 5/24 20130101; Y10T
442/2992 20150401; C08L 1/02 20130101; C08L 61/24 20130101; C09J
103/04 20130101; C03B 37/04 20130101; C08J 2303/04 20130101; D04H
1/587 20130101; C09J 103/04 20130101; C08K 5/0025 20130101; C09J
103/04 20130101; C08K 5/0025 20130101; C08K 7/04 20130101; C09J
103/04 20130101; C08K 5/0025 20130101; C08K 7/14 20130101; C09J
103/04 20130101; C08K 5/0025 20130101; C08L 97/02 20130101; C09J
103/04 20130101; C08K 5/0025 20130101; C08L 1/02 20130101; C09J
103/04 20130101; C08K 5/0025 20130101; C08L 89/00 20130101; C09J
103/04 20130101; C08K 5/0025 20130101; C08L 67/00 20130101; C09J
103/04 20130101; C08K 5/0025 20130101; C08L 23/00 20130101; C09J
103/04 20130101; C08K 5/0025 20130101; C08L 33/08 20130101; C09J
103/04 20130101; C08K 5/0025 20130101; C08L 77/00 20130101; C09J
103/04 20130101; C08K 5/0025 20130101; C08L 77/02 20130101; C09J
161/24 20130101; C08K 5/0025 20130101; C08L 3/04 20130101; C08L
61/24 20130101; C08K 5/0025 20130101; C08L 3/04 20130101 |
Class at
Publication: |
442/180 ;
106/212.1; 106/162.51; 524/47; 524/734; 977/773 |
International
Class: |
C09D 103/00 20060101
C09D103/00; B32B 17/04 20060101 B32B017/04; C09D 197/02 20060101
C09D197/02; C09D 161/24 20060101 C09D161/24 |
Claims
1. A curable composition, the composition comprising: a latex
including particles comprising crosslinked biopolymer molecules;
and a crosslinking agent in solution with the latex.
2. The curable composition of claim 1 wherein: the biopolymer
molecules comprise amylose or amylopectin.
3. The curable composition of claim 1 wherein: the particles have
an average particle size in the range from 1 to 1000
nanometers.
4. The curable composition of claim 1 in combination with a
plurality of fibers or wood in a form other than pulp.
5. The curable composition of claim 1 in combination with a
plurality of mineral fibers.
6. The curable composition of claim 1 further comprising a
non-biopolymer binder or a non-biopolymer latex.
7. The curable composition of claim 1 further comprising a
polycarboxylic acid binder or a polyester binder.
8. The curable composition of claim 1 wherein the crosslinking
agent is a silicate crosslinking agent.
9. The curable composition of claim 1 wherein the particles are
formed by reactive extrusion processing.
10. The curable composition of claim 1 wherein: the particles are
present in the curable composition at a concentration of between 4%
and 20% by weight of the curable composition.
11. A composition comprising, a) an aqueous binder; b) dispersion
of particles in the aqueous binder; and, c) a crosslinker in
solution with the aqueous binder adapted to bond to the particles
and to mineral fibers.
12. The composition of claim 11 wherein the particles comprise
crosslinked starch.
13. The composition of claim 11 wherein the particles form a
colloidal dispersion in the aqueous binder.
14. The composition of claim 11 wherein the curable binder is
substantially formaldehyde free of has less than 1 ppm of
formaldehyde based on the weight of the composition.
15. The composition of claim 11 wherein the crosslinker is a
silicate crosslinker.
16. The composition of claim 11 in combination with a non-woven mat
of glass fibers.
17. A composition comprising, a) an aqueous formaldehyde binder; b)
a dispersion of particles in the aqueous binder, the particles
comprising crosslinked biopolymers.
18. The composition of claim 17 wherein the particles are added
during the polymerization of urea and formaldehyde.
19. The composition of claim 17 in combination with a mat of glass
fibers and asphalt.
20. A composite material comprising: a binder comprising particles
selected from the group consisting of a) particles made of
crosslinked biopolymers, b) particles having an average size of
less than 400 nm, c) particles having a volume swell ratio of 6 or
more and d) particles comprising starch; and, a material comprising
mineral fibers or non-pulped wood.
Description
CROSS-REFERENCES TO RELATED APPLICATIONS
[0001] This patent claims the benefit of U.S. provisional patent
application No. 61/493,266 filed on Jun. 3, 2011 which is
incorporated herein by this reference to it.
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH
[0002] Not Applicable.
BACKGROUND OF THE INVENTION
[0003] 1. Field of the Invention
[0004] This invention relates to a curable composition, for example
a composition useful for forming a composite material comprising
biopolymer particles, and to composite materials, for example
mineral fiber insulation and roofing shingles.
[0005] 2. Description of the Related Art
[0006] The following discussion is not an admission that anything
described below is common knowledge of persons skilled in the art,
or citable as prior art.
[0007] Mineral fibers used in insulation products and non-woven
mats are usually bonded together with a crosslinked binder resin.
The binder has to provide the resilience for recovery after
packaging (in the case of insulation products) as well as stiffness
and compatibility between individual fibers.
[0008] The process for making mineral fiber products such as
fiberglass insulation typically includes melting minerals, sand or
recycled glass, producing a molten glass stream that is passed
through high pressure air fiberizers or "spinning wheels" where the
glass is then spun into thin fibers and transported onto a belt to
form the fiberglass insulation product. Given the enormous volume
and surface area expansion, the temperature drops almost
instantaneously from the red hot mineral stream to the relatively
cool mineral fibers. This rapid drop in temperature facilitates the
application of an aqueous polymeric binder composition immediately
following the fiberizer without substantially degrading the polymer
and other binder components, and more importantly, without
triggering premature curing and crosslinking such that the
subsequent sections of the manufacturing process can be used to
control the dimensions of the fiberglass mat product. The fibers
are then blown to a conveyor through a forming chamber where they
are dried and cured. As part of this process, the coated mat is
generally transferred to a forming or air-fluffing chamber and
subsequently a curing oven to cure the binder and bond the glass
fibers together. Prior to the curing process, the degree of
fluffing facilitates the control over the dimensions of the
particular grade of mineral fiber product.
[0009] The dominant binders for insulation and non-woven mats as
well as for wood products are formaldehyde based resins, such as
phenol-formaldehyde (PF), melamine-formaldehyde (MF), and
urea-formaldehyde (UF) resins and the like, as well as mixed
phenol/urea-formaldehyde (P/UF) resins and the like. A serious
disadvantage of formaldehyde-based resins is the release of free
formaldehyde to the environment during manufacturing and use,
contaminating the air that we breathe which is undesirable for
health and ecological reasons. Note that formaldehyde has been
reported to be a human carcinogen (IARC 2004. IARC Classified
Formaldehyde as Carcinogenic to Humans. IARC Press Release No. 153.
International Agency for Research on Cancer, available at
www.iarc.fr/en/media-centre/pr/2004/pr153.html. Substances Profile:
Formaldehyde Gas. Report on Carcinogens, 11th Edition. National
Toxicology Program, available at
http://ntp.niehs.nih.gov/ntp/roc/eleventh/profiles/s089form.pdf;
and National Emissions Standard for Formaldehyde in Composite Wood
Products Becomes Law, found at
http://www.aqs.com/DesktopDefaultaspx?mid=168&tabid=82&ItemId=30).
In addition to the health and environmental problems, further
compounding the problem is that the lowest cost formaldehyde based
binders are based on UF resins. Therefore, UF has traditionally
been the dominant binder system used in mineral fiber products,
fiberglass insulation, nonwovens as well as wood products, such as
particle board, plywood and oriented strand board (OSB) products.
Of all the formaldehyde based resins, UF is the least stable to
hydrolysis especially at elevated temperature (30-45.degree. C., or
higher) and humidity, it has commonly been the preferred binder for
indoor uses (such as particle board used in kitchen cabinets,
countertops, furniture, etc.), where air contamination and human
exposure risks are highest. This problem recently gained visibility
in the US when hurricanes Katrina and Rita devastated the
Louisiana, Mississippi and Alabama coastlines. The problem was
brought to the forefront following serious health and air quality
complaints by displaced hurricane victims and concerns arose over
high levels of formaldehyde found in some travel trailers and
temporary housing (FEMA trailers). Survivors housed in the trailers
were exposed to high levels of formaldehyde due to the hot and
humid conditions of the local climate (Four Years Later:
Formaldehyde Exposure & Emissions Standards, Product
Evaluations Technology Brief by Air Quality Sciences, Inc., Volume
9, Issue 9). The somewhat more costly pure PF and MF resins are
generally more stable to hydrolysis. These resins are typically
used in outdoor applications, and therefore their main challenge is
worker exposure during manufacturing, while in-use release of
formaldehyde is less of a concern, especially in outdoor
applications. Note, however, that PF resin products shipped by the
resin supplier may contain a significant level of free
formaldehyde, which then needs to be reduced by the downstream
(e.g. fiberglass) manufacturer in a pre-reaction. This is commonly
done using urea to capture most of the free formaldehyde to result
in mixed P/UF binder systems. Thus, the so-called PF binders used
in these applications actually are P/UF systems which are prone to
more free formaldehyde release in use given the UF portion is less
stable to hydrolysis, especially at temperatures between
30-45.degree. C., or higher.
[0010] In addition, formaldehyde based binders are petroleum-based
synthetic products. In an era of depleting oil reserves and
increasing costs of petrochemicals, the need to wean our industries
away from their dependence on foreign oil has become paramount.
Plant, animal and agro-based materials are in balance with nature
and are "carbon neutral", whereas petro-based materials are not
because they are "carbon positive" (see Phil Greenall and Steven
Bloembergen, "New generation of biobased latex coating binders for
a sustainable future", Paper Technology 52, No. 1, Paper Industry
Technical Ass'n, p. 10-14, February 2011; and Do Ik Lee, Steven
Bloembergen, and John van Leeuwen, "Development of New Biobased
Emulsion Binders", PaperCon2010 Meeting, "Talent, Technology and
Transformation", Atlanta, Ga., May 2-5, 2010). Biobased materials
offer a much reduced carbon footprint, and green agro-based
products are becoming more and more important in an age where
greenhouse gas (GHG) emissions are escalating.
[0011] However, traditional biobased industrial materials derived
from agricultural crops are generally viewed by manufacturing and
packaging industries as less consistent and inferior to the
dominant petrochemical-based synthetic products.
[0012] Various attempts have been made to reduce undesirable
formaldehyde emissions as well as developing formaldehyde-free
binders and use other synthetic oil-derived polymer resins, as well
as traditional modified soluble starches, dextrins or other low
performance biobased materials. However, these have serious
shortcomings such as high cost, high corrosivity, high viscosity,
dark color, lack of rigidity, water sensitivity, poor bond
strength, etc.
[0013] A number of formaldehyde-free compositions have been
developed for use as a binder for making nonwoven products.
[0014] U.S. Pat. No. 5,977,232 discloses a formaldehyde-free binder
for glass wool insulation based on carboxylic acid which is
corrosive due to the low pH of the system. This technology has been
found to result in major corrosion problems with the equipment used
to manufacture fiberglass insulation products, as well as in-use
applications where metal wall studs and other metal components are
being used in combination with the fiber glass insulation
product.
[0015] U.S. Patent Application Publication No. 2003/0008586
discloses the use of polyvinyl alcohol (PVOH) as a
formaldehyde-free binder solution for low binder nonwoven fiber mat
useful for making wood product laminates. The binder produces high
bonding strength with wood and is characterized by a relatively
good storage stability (relative to formaldehyde resins). The
binder is used at 5% concentration. The problem is the much higher
cost of PVOH relative to conventional formaldehyde binder systems.
In addition, since it is petroleum based it is a carbon positive
material which is not environmentally preferred. Without any
additional enhancer, this binder does not provide sufficient wet
strength and water resistance.
[0016] U.S. Pat. Nos. 6,221,973 and 6,331,350 describe a
formaldehyde-free fiberglass binder including a polyacid, such as
polyacrylic acid, and a polyol, with a molecular weight less than
about 1000, such as, for example, glycerol, triethanolamine,
sorbitol, or ethylene glycol. A phosphorous catalyst is used to
accelerate the cure of the composition. The major disadvantage of
this binder is high cost and low pH which causes corrosion of fiber
glass mat production equipment and during in-use applications.
[0017] PCT Patent Application Publication No. WO 2006/120523
describes a polyvinyl alcohol-based formaldehyde-free curable
aqueous composition comprising PVOH crosslinked with
multifunctional crosslinking agent (e.g. nonpolymeric polyacid,
polyaldehyde or anhydride). Disadvantages of this system are low pH
and high viscosity at relatively low solids content. The problems
as mentioned above include the much higher cost of PVOH relative to
conventional formaldehyde binder systems, and since it is petroleum
based it is a carbon positive material which is not environmentally
preferred. This binder is also corrosive due to relatively low pH
(about 4) and does not provide the required water resistance.
[0018] U.S. Pat. No. 6,884,849 describes a polyalcohol-based binder
composition comprising a low molecular weight polycarboxylic acid
and a low molecular weight polyalcohol, such as PVOH having an
average molecular weight between 200 and 13,000. The binder
solution preferably comprises at least one cure catalyst or
accelerator, such as sodium hypophosphite. The binder exhibits a
high cure rate and provides a good recovery of the final nonwoven
product. However, a practical use of such a composition for
insulation production is limited because the high acidity of these
binder compositions will cause corrosion of production lines and
during the in-use applications. Moreover, whilst the strength of
this binder is acceptable for some applications it is not as good
as the commonly used formaldehyde based binders. In addition, since
it is petroleum based it is a carbon positive material which is not
environmentally preferred.
[0019] U.S. Patent Application Publication No. 2004/0038017
describes a binder composition containing a substantially
infinitely water-dilutable or dispersible adduct of a monomeric
polycarboxylic acid component and a monomeric polyol component to
yield a polyester. This binder requires a much longer time (up to
15 minutes) for curing under standard curing conditions, or a much
higher temperature (of about 300.degree. C.), which a serious
disadvantage.
[0020] U.S. Patent Application Publication No. 2010/0080976
discloses formaldehyde-free mineral fiber insulation product based
on a combination of polycarboxylic acid, sugar and ammonia. Such a
system has relatively low water resistance, is dark in color and
generates ammonia emissions upon cure. In addition, since it is
petroleum based it is a carbon positive material which is not
environmentally preferred.
[0021] Formaldehyde free binders disclosed in U.S. Patent
Application Publication No. 2007/0142596 and GB 2451719A relate to
binders comprising Maillard reactants, in particular dextrose
systems derived from a mixture of dextrose monohydrate, anhydrous
citric acid, water and aqueous ammonia. These binders turn dark
brown on curing and have poor water and biological resistance.
[0022] While these references and other prior art systems disclose
various formaldehyde-free systems for insulation and non-woven
mats, they all have limitations with respect to developing binders
that are effective as well as environmentally friendly.
[0023] High strength fiber mats are extremely popular in the
building materials industry. Most non-woven fiber mats have
numerous applications, including use in roofing, siding and floor
underlayment, insulation facers, floor and ceiling tiling, and
vehicle parts. The most common use of fiber mats is in roofing
shingles, and in particular in asphalt roofing shingles.
[0024] Various fiber mats and methods of making the same have been
previously described. For example, U.S. Pat. Nos. 4,135,029,
4,258,098, 5,914,365, and 6,642,299 describe glass fiber mats made
by a wet-laid process. Glass fiber mats made by the wet-laid
process are formed from glass fibers held together by a binder
material. The last two patents (U.S. Pat. Nos. 5,914,365 and
6,642,299) relate to improved wet web strength with styrene-maleic
anhydride copolymer (SMA), styrene-acrylate copolymers, and
mixtures thereof. These binders have limited application due to
high cost. In addition, they are petroleum based carbon positive
materials which are not environmentally preferred.
[0025] Typically, in wet processed glass fiber mats, the binder is
applied in liquid form and dispersed onto the glass fibers by a
curtain type applicator. Conventional wet processes strive to
produce a uniform coating of binder on the glass fibers. After the
binder and glass fibers have been dried and cured, the glass fiber
mat is cut as desired.
[0026] A major problem in the manufacturing process and use of some
known fiber mats is inadequate wet web strength. The wet web
strength of wet glass mat has significant impact on runability of
glass mat production and mat properties. In order to prevent the
wet (glass mat) web from breaking during production, the production
line speed has to be reduced due to lower wet web strength of the
glass mat prior to curing. Also, lower wet web strength requires
higher vacuum draw to support the wet web and minimize web breaks.
But higher vacuum draw will lead to undesired mat properties, such
as a high mat tensile ratio (i.e. the ratio of dry to wet tensile
strengths).
[0027] Inadequate dry mat tensile strengths also can reduce the
ability of the finished roofing product to resist stresses during
its service lifetime on the roof. Because building materials
generally, and roofing shingles in particular, are often subjected
to a variety of weather conditions, the fiber mats should also
maintain their strength characteristics under a wide range of
conditions.
[0028] Among the attempts of improving glass fiber mat tensile
strength, U.S. Pat. No. 4,430,158 claims improved tensile strength
to a sized glass fiber mat by adding an anionic surfactant, such as
sodium dodecylbenzene sulfonate, to the urea formaldehyde binder
system, and U.S. Pat. No. 4,542,068 discloses a method of making a
glass fiber mat in which a synthetic styrene butadiene binder
system plus an alkoxylated alkylamine is employed, while U.S. Pat.
No. 7,272,915 describes a urea formaldehyde binder modified with
acrylonitrile-butadiene-styrene copolymer providing increased
tensile strength. A major problem in the manufacturing process and
use of fiber mats is inadequate wet web strength, which cannot be
provided by a urea formaldehyde resin without an additive, as
illustrated by the related art described in this paragraph. In
addition, since these binders are all petroleum based they are
carbon positive materials and therefore not environmentally
preferred.
[0029] U.S. Pat. No. 7,268,091 discloses a urea-formaldehyde fiber
binder; and a vinylpyrrolidone/acrylic acid/lauryl methacrylate
terpolymer. An aqueous binder composition containing a
urea-formaldehyde resin modified with a water-soluble
styrene-maleic anhydride copolymer is used in the preparation of
fiber mats is described in U.S. Pat. No. 6,084,021. The main
disadvantage of these binders is a necessity of preparing the
binder before applying it on the glass fiber mat due to a limited
stability of a resin/latex mixture. In addition, since these
binders are petroleum based they are carbon positive materials
which are not environmentally preferred.
[0030] In summary, various attempts have been made to reduce
undesirable formaldehyde emissions as well as developing
formaldehyde-free binders and use traditional modified starches and
dextrins or other low performance bio-based materials. However, all
of these to date have serious shortcomings such as high cost, high
corrosivity, high viscosity, dark color, lack of rigidity, water
sensitivity, poor bond strength, etc.
[0031] Multiple disclosures have been made regarding the
composition and use of various forms of biopolymer nanoparticles.
For instance, U.S. Pat. No. 6,677,386 (which corresponds to WO
00/69916) describes a process for producing biopolymer
nanoparticles, which in one form are starch nanoparticles. In the
process, the biopolymer is plasticized using shear forces, and a
crosslinking agent is added during the processing. After the
processing, the biopolymer nanoparticles can be dispersed in an
aqueous medium. One version of the process results in starch
nanoparticles which are characterized by an average particle size
of less than 400 nanometers. The nanoparticles can be used as a
matrix material wherein the matrix material may be a film-forming
material, a thickener, a rheology modifier, an adhesive or an
adhesive additive (tackifier). The nanoparticles or dispersions
thereof may also be used for their barrier properties, as a
carrier, fat replacer or medicament for mitigating dermal
disorders. Further examples of applications for the nanoparticles
or dispersions thereof are in the paper-making and packaging
industry, agriculture and horticulture fields. The nanoparticles
can also be used as excipients or carriers in medicines, where they
may be complexed or covalently coupled to active substances such as
slow-release drugs. The nanoparticles can also be processed into a
foam at relatively high density.
[0032] Other uses of the nanoparticles of U.S. Pat. No. 6,667,386
can be found in: (i) U.S. Pat. No. 7,160,420 which describes the
use of the starch nanoparticles as a wet-end additive in
papermaking pulp slurry, or applied to the surface of the paper as
a surface sizing agent; (ii) U.S. Pat. No. 6,825,252 which
describes the use of the starch nanoparticles in a binder in a
pigmented paper coating composition; (iii) U.S. Pat. No. 6,921,430
which describes the use of the starch nanoparticles in
environmentally friendly adhesives; and (iv) U.S. Patent
Application Publication No. 2004/0241382 which describes the use of
the starch nanoparticles in an adhesive for producing corrugated
board. The disclosure of these patents and published applications,
and of all other publications referred to herein, are incorporated
by reference as if fully set forth herein.
[0033] The invention in U.S. Pat. No. 6,667,386 relates to a
process for producing biopolymer nanoparticles which in one form
are starch nanoparticles characterized by an average particle size
of less than 400 nanometers. The structure of the biopolymer
nanoparticles has been described in the literature (see Bloembergen
et al., "Specialty Biobased Monomers and Emulsion Polymers Derived
from Starch", 2010 PTS Advanced Coating Fundamentals Symposium,
Munich, Germany, Oct. 11-13, 2010). In dry form, the product
consists of larger agglomerates with an average agglomerate
particle size of .about.300 .mu.m (300,000 nm.), from which
nanoparticles are released when they are dispersed in water. In
dispersed form, the biopolymer nanoparticles exist as insoluble
colloidal particles that form a biopolymer latex dispersion with an
average size of .about.100 nanometers. Each of the nanoparticles
can be thought of as internally crosslinked macromolecular units
with intra-particle crosslinks (FIG. 1). No inter-particle
crosslinks exist, as this would result in poor rheology and reduced
binding power (reduced surface area). Excellent paper coating
binding strength and rheological properties (superior machine
runability) have been reported by coated paper and board
manufacturers and paper industry experts (see Klass, C. P., "New
Nanoparticle Latex offers Natural Advantage", Paper360.degree.
Magazine, p. 30-31, January, 2007; Figliolino et al., "Reducing
Carbon Footprint with Biolatex", Paper360.degree. Magazine, p.
25-28, August, 2009; Lee et al., "Development of New Biobased
Emulsion Binders", PaperCon2010, "Talent, Technology and
Transformation", Atlanta, Ga., May 2-5, 2010; Greenall et al., "New
generation of biobased latex coating binders for a sustainable
future", Paper Technology 52, No. 1, Paper Industry Technical
Ass'n, p. 10-14, February 2011; and Oberndorfer et al., "Coating
& print performance of biobased latex in European graphic
papers", PaperCon2011, "Rethink Paper: Lean and Green", Cincinnati,
Ohio, May 1-5, 2011). The biopolymer latex binder provides a high
performance substitute to the petrochemical-based binders used in
coated paper and paperboard manufacturing processes at a lower cost
per pound. Carboxylated or acrylonitrile or otherwise modified
styrene butadiene (SB latex) and styrene acrylate (SA latex) are
the dominant petrochemical-based binders used in coated paper and
paperboard manufacturing. Currently, the industry consumes over 4
billion pounds of SB and SA latex per annum. As the price of oil
continues to escalate, and as the price of synthetic binders has
increased by more than 100% over the past few years, paper
producers have faced increased production costs forcing them to
find efficiencies, pass increases on to the consumer, or cease
production. The biopolymer latex binder of U.S. Pat. No. 6,667,836
provides performance that is comparable to the petro-based SB and
SA latex products for important paper properties such as coating
gloss, brightness, whiteness, fluorescence, ink gloss, and
printability, while providing superior performance to SB and SA
Latex for water retention, opacity, dry pick, print mottle,
porosity (blister resistance) and paper stiffness.
SUMMARY OF THE INVENTION
[0034] The following discussion is intended to introduce the reader
to the detailed description, and not to limit any claimed
invention. An invention may reside in any combination or
sub-combination of elements or steps described in this summary, the
figures or the detailed description.
[0035] This specification describes compositions useful, for
example, in providing an alternative means of making one or more of
mineral, natural organic or synthetic fibers products.
[0036] The inventors demonstrate, among other things, novel and
non-obvious uses for biopolymer nanoparticles such as those
described in U.S. Pat. No. 6,667,836, a new curable binder
composition comprising a biopolymer nanoparticles, in some
applications with a multifunctional crosslinking agent, for use for
example in the formation of mineral, natural organic, or synthetic
fiber products, for example mineral fiber insulation, non-woven
mats, fiberglass insulation and related glass fiber products, and
wood based products, and construction materials. By
"multifunctional cross linking agent", we mean a crosslinking agent
in addition to a crosslinking agent used to form the biopolymer
nanoparticle. The multifunctional crosslinking agent has two or
more functional groups (which may be the same type of functional
group) capable of forming a bond, for example a covalent or ionic
bond, with the nanoparticles and preferably with the fibers.
[0037] Curable aqueous compositions are described, for example a
formulation comprising nanoparticles of crosslinked starch and a
multifunctional crosslinking agent. Whereas the biopolymer
nanoparticles in the aqueous dispersion are already internally
crosslinked within the nanoparticles via intra-particle crosslinks,
the additional multifunctional crosslinking agent facilitates
interfacial inter-particle crosslinks. In an application wherein a
curable aqueous composition is used to make fiberglass insulation,
a multifunctional crosslinking agent is selected which lies at
least partially dormant during the binder application stage and
fiber mat formation and fluffing stages, but is triggered in the
curing stage to react, or react further, and lock in the desired
fiber mat dimensions. The high surface area of the biopolymer
nanoparticles in the aqueous composition provides bonding for
mineral, natural organic or synthetic fibers which is superior to,
or at least offers an alternative to, water-soluble sugars,
dextrins, industrial starches, carbohydrates or other natural
polymers. The additional multifunctional crosslinking agent
facilitates interfacial inter-particle crosslinks to provide useful
fiber mat recovery (for insulation products) and dry and wet
tensile strength properties.
[0038] The multifunctional crosslinker may be selected from
dialdehydes, polyaldehydes, anhydrides such as acid anhydrides or
mixed anhydrides, (e.g. succinic and maleic anhydride),
glutaraldehyde, glyoxal, oxidized carbohydrates, periodate-oxidized
carbohydrates, epichlorohydrin, epoxides, triphosphates,
petroleum-based monomeric, oligomeric and polymeric crosslinkers,
biopolymer crosslinkers, divinyl sulphone, borax (Na2B4O7.10H2O),
isocyanates, polyacids and hydrolysable organo alkoxy silanes
producing silanols. The crosslinking reaction may be acid-catalyzed
or base-catalyzed. In one embodiment, suitable dialdehydes and
polyaldehydes include glutaraldehyde, glyoxal, periodate-oxidized
carbohydrates, and the like. Glyoxal, borax, epichlorohydrin,
isocyanates, anhydrides, polyacids and silicates such as tetraethyl
orthosilicate (TEOS) are particularly suitable crosslinkers. Such
crosslinkers may be used alone or as a mixture of crosslinkers. The
level of crosslinking agent can conveniently be between 0.1 and 10
weight % with respect to the total dry weight of the curable
aqueous composition. The level of crosslinking agent can also be
between 0.1 and 5 weight % with respect to the total dry weight of
the curable aqueous composition. The level of crosslinking agent
can also be between 0.5 and 5 weight % with respect to the total
dry weight of the curable aqueous composition. The level of
crosslinking agent can also be between 0.1 and 2 weight % with
respect to the total dry weight of the curable aqueous
composition.
[0039] A cured composition is described in this specification
comprising a nonwoven fiber in a cured binder wherein the cured
composition is formed by mixing fibers in a curable aqueous
composition to form a mixture and curing the mixture.
[0040] A method for forming a non-woven material is described in
this specification comprising: mixing fibers a said curable aqueous
composition, and heating the curable composition and fibers at
130.degree. C. to 230.degree. C. for sufficient time to cure.
[0041] A method for binding together a loosely associated mat of
glass fibers is described in this specification comprising
contacting the glass fibers with an aqueous binder composition
comprising an aqueous mixture of a substantially infinitely
water-dilutable or dispersible adduct of co-condensation of urea,
formaldehyde and nanoparticles of crosslinked biopolymer containing
plurality of pendant hydroxyl groups and heating said composition
at an elevated temperature to effect cure.
[0042] A glass fiber product is described in this specification
comprising a crosslinked (cured) composition obtained by curing
(drying at elevated temperature) an aqueous binder composition
comprising a substantially infinitely water-dilutable or
dispersible adduct of co-condensation of urea, formaldehyde and
nanoparticles of crosslinked biopolymer containing plurality of
pendant hydroxyl groups applied to a mat of nonwoven glass
fiber.
[0043] A mineral, natural organic, or synthetic wool product is
described in this specification comprising a crosslinked (cured)
composition obtained by curing (drying at elevated temperature) an
aqueous binder composition comprising a substantially infinitely
water-dilutable or dispersible adduct of co-condensation of urea,
formaldehyde and nanoparticles of crosslinked biopolymer containing
plurality of pendant hydroxyl groups applied to a mat of nonwoven
mineral, natural organic, or synthetic wool.
[0044] A composition is described in this specification comprising
an aqueous solution comprising a curable binder, a dispersion of at
least 25 wt % of particles in the aqueous solution and a
crosslinker adapted to bond to the particles and to mineral fibers.
The composition may be used to make mineral fiber insulation, for
example fiberglass insulation. The curable binder may be a
non-formaldehyde resin, for example polyacrylic acid (PAA) or
polyester (PE).
[0045] A composition is described in this specification comprising
a formaldehyde resin and a dispersion of up to 15 wt % of particles
comprising crosslinked biopolymers. The composition may be used to
make fiberglass roofing shingles.
[0046] A composite material is described in this specification
comprising particles, fibers, and a crosslinker bonded to the
fibers and the particles wherein the particles are one or more
particles selected from the group of cross linked biopolylers,
particles with an average size of less than 400 nm, and particles
with a volume swell ratio greater than 6.
[0047] A curable aqueous compositions for fiber mat formation
described in this specification comprise a biopolymer latex
formulation comprising nanoparticles of crosslinked starch and a
multifunctional crosslinking agent. The multifunctional
crosslinking agent may lie dormant during a binder application
stage and fiber mat formation and fluffing stages, but is triggered
in the curing stage to react and lock in the desired fiber mat
dimensions.
[0048] A curable aqueous composition for fiber mat formation
described in this specification comprises a biopolymer latex
formulation comprising nanoparticles of crosslinked starch and a
multifunctional crosslinking agent wherein said multifunctional
crosslinking agent facilitates interfacial inter-particle
crosslinks.
[0049] A curable aqueous composition for fiber mat formation
described in this specification comprises a biopolymer latex
formulation comprising nanoparticles of crosslinked starch and a
multifunctional crosslinking agent wherein said multifunctional
crosslinking agent facilitates a useful fiber mat recovery and dry
and wet tensile strength properties.
[0050] A reduced total emission process for preparing of a
binder-coated nonwoven product described in this specification
includes the preparation of a curable aqueous binder composition
comprising a biopolymer nanoparticles; applying the binder to the
nonwoven fibers to form a binder-containing nonwoven mat; curing
the binder-containing nonwoven mat at elevated temperatures to form
the binder-coated nonwoven product.
BRIEF DESCRIPTION OF THE DRAWINGS
[0051] FIG. 1 is a schematic that illustrates the intra-particle
crosslinked structure of a biopolymer nanoparticle, with "--R--"
representing a crosslink between different starch polymers located
within the biopolymer nanoparticle.
[0052] FIG. 2 is a schematic illustrating delayed inter-particle
crosslinking of a biopolymer nanoparticle composition during the
final drying and curing stage of a fiberglass insulation product,
where "R" represents an unreacted multifunctional crosslinking
reagent and "X" represents the reacted reagent facilitating
inter-particle crosslinks; the interfacial inter-particle
crosslinking agent lies dormant during the binder application stage
and the fiber mat formation and fluffing stages, but is triggered
in the curing stage to lock in the desired fiber mat
dimensions.
[0053] FIG. 3 is a schematic of a cured mineral, natural organic,
or synthetic fiber product made from a curable aqueous composition
comprising biopolymer nanoparticles of crosslinked starch and a
multifunctional crosslinking agent.
[0054] FIG. 4 is an SEM micrograph (at 500.times. magnification) of
a glass fiber mat to which a biopolymer latex formulation
comprising nanoparticles of crosslinked starch and a
multifunctional crosslinking agent has been added following which
it was cured, and serves to illustrate "spot welding", or fiber to
fiber bonding, with the biopolymer latex binder composition
containing a multifunctional crosslinker.
[0055] FIG. 5 is an SEM micrograph (at 2,500.times. magnification)
of a glass fiber mat to which a biopolymer latex formulation
comprising nanoparticles of crosslinked starch and a
multifunctional crosslinking agent has been added following which
it was cured, and serves to illustrate extensive interfiber "spot
welding", or fiber to fiber bonding, with the biopolymer latex
binder/multifunctional crosslinker composition.
[0056] FIG. 6 is a High Resolution SEM micrograph (at 30,000.times.
magnification) of a spot weld, or fiber to fiber bond, area in a
fiber mat made with a cured binder composition consisting of 50%
polyacrylic acid (PAA) resin-50% biopolymer latex binder by solids
weight composition containing a multifunctional crosslinker.
DETAILED DESCRIPTION OF THE INVENTION
[0057] Before the present materials and methods are described, it
is understood that this invention is not limited to the particular
methodology, protocols, materials, and reagents described, as these
may vary. It is also to be understood that the terminology used
herein is for the purpose of describing particular embodiments
only, and is not intended to limit the scope of the present
invention.
[0058] It must be noted that as used herein and in the appended
claims, the singular forms "a", "an", and "the" include plural
reference unless the context clearly dictates otherwise. As well,
the terms "a" (or "an"), "one or more" and "at least one" can be
used interchangeably herein. It is also to be noted that the terms
"comprising", "including", and "having" can be used
interchangeably.
[0059] Unless defined otherwise, all technical and scientific terms
used herein have the same meanings as commonly understood by one of
ordinary skill in the art to which this invention belongs. Although
any methods and materials similar or equivalent to those described
herein can be used in the practice or testing of the present
invention, the preferred methods and materials are now described.
All publications and patents specifically mentioned herein are
incorporated by reference for all purposes including describing and
disclosing the chemicals, instruments, statistical analysis and
methodologies which are reported in the publications which might be
used in connection with the invention. Nothing herein is to be
construed as an admission that the invention is not entitled to
antedate such disclosure by virtue of prior invention.
[0060] By "biopolymer" we mean biopolymers such as starch, starch
derivatives, and carbohydrates or other polysaccharides including
cellulose, hemicellulose and gums, as well as proteins (e.g.
gelatin or whey protein) that can be formed into nanoparticles. The
biopolymers may be previously modified, e.g. with cationic groups,
carboxymethyl groups, by acylation, phosphorylation,
hydroxyalkylation, oxidation and the like. Starch, and mixtures of
different starch species, and mixtures of starch with other
(bio)polymers containing at least 50% starch are preferred.
Especially preferred is high-amylopectin starch (i.e. low-amylose
starch), i.e. starch having a content of at least 75%, especially
at least 90% of amylopectin, such as waxy starch.
[0061] By "biopolymer nanoparticle" we mean a particle comprising
crosslinked biopolymer molecules. A dispersion of biopolymer
nanoparticles may include particles, or may have an average size
(by number or mass, or the D50 value of an NTA measurement) of
particle, between 1 and 2500 nanometers (nm), or between 1 and 1000
nm or between 1 and 400 nm. Particles within the smaller size
ranges are preferred because they provide increased surface for
inter-particle bonding. Smaller particles are also easier to
disperse or maintain in dispersion, and are more likely to form a
colloid. However, in some applications, particles with an average
size even larger than 2500 nm might be used.
[0062] The size of the particles can be determined by forming a
dispersion of the particles and making a measurement using, for
example, Nanoparticle Tracking Analysis (NTA) using an LM 20
tracking analysis device (NanoSight Ltd.) equipped with a blue
laser (405 nm). This device uses a 50 mW laser operating in the CW
mode to illuminate the particles. The light scattered by the
particles is captured using a digital camera and the motion of each
particle is tracked from frame to frame using NanoSight software. A
high speed video is obtained (30 frames per second, average video
about 30 s). The trajectories of individual particles are generated
from the video sequence and the mean squared displacement
determined for each particle. Typically at least 20 trajectories
are acquired and 250 to 500 sets of trajectories (each set
corresponding to an individual particle) are accumulated in a video
sequence. The analysis of the mean squared displacement is used to
calculate the diffusion coefficient and the hydrodynamic radius
(r.sub.h) is determined using the Stokes-Einstein equation. Thus,
the diameter of each particle in the sample can be determined and a
particle size distribution derived. Because a diffusion coefficient
is obtained for each particle in the field of view, a particle size
distribution can be obtained which does not assume a particular
mathematical model as in dynamic laser light scattering (DLS)
analysis.
[0063] As an alternative, DLS measurements may also be used. In
that case, the dispersion is diluted as required by the instrument
and preferably filtered to remove any remaining agglomerates. DLS
and NTA are complementary, given that the NTA technique is a direct
measurement of the diffusion coefficient for individual particles
tracked via video tracking software (and relates that to particle
diameter via the Stokes-Einstein equation), and can measure
particles in the range of 50-1000 nm, while DLS can measure to
smaller particle sizes below 50 nm. Other useful techniques include
oscillating probe Atomic Force Microscopy (AFM), Scanning Electron
Microscopy (SEM), Environmental SEM (ESEM), Transmission Electron
Microscopy (TEM) and Scanning/Transmission Electron Microscopy
(STEM).
[0064] By "biopolymer nanoparticle latex", "biopolymer latex" we
mean a colloidal dispersion of biopolymer nanoparticles. The
particles in a biopolymer latex typically have an average size
between about 1 and 1000 nm.
[0065] By "starch" we mean a complex carbohydrate polymer which is
insoluble in water. Starch is often found in the fruit, seeds, or
tubers of plants. The major resources for starch production and
consumption are corn, potatoes, wheat, tapioca and rice. Starch is
a mix of two polymeric carbohydrates (polysaccharides) called
amylose and amylopectin, in which the monomers are glucose units
joined to one another head-to-tail forming alpha-1,4 linkages. The
overall structure of amylopectin is not, however, simply a linear
polysaccharide chain, since occasionally, two glucose units are
joined to one in an alpha-1,6 linkage, forming a branch point.
Structurally, the starch forms clusters of linear polymers, where
the alpha-1,4 linked chains form linear columns of glucose units
branching at the alpha-1,6 links. The relative content of amylose
and amylopectin varies between starch species.
[0066] Note that EcoSynthetix.RTM., EcoSphere.RTM., and
Biolatex.RTM., are registered trademarks of EcoSynthetix Ltd. of
Lansing, Mich., USA. Ecosphere 2202.TM. is a starch based,
internally crosslinked colloid forming hydrogel particle having an
average particle size under 400 nm available commercially from
EcoSynthetix Ltd., or Ecosynthetix Inc. of Burlington, Ontarion,
Canada. In particular, the Ecosphere 2202.TM. particles have a
number average particle size in the range of 50 to 150 nm and,
considering a distribution of their particle sizes, are also
predominantly in the range of 50 to 150 nm in size. These products
are made primarily from starch including amylose and amylopectin.
The product is normally sold for to replace petroleum based latex
binders in industrial applications, such as coated paper and
paperboard. The product is provided in the form of a dry powder of
agglomerated nanoparticles with a volume mean diameter of about 300
microns. When mixed in water and stirred, the agglomerates break
apart and form a stable dispersion of the nanoparticles.
[0067] This specification describes, among other things, a novel
and non-obvious use for biopolymer nanoparticles, such as those
described in U.S. Pat. No. 6,667,836, in achieving a new curable
binder composition comprising a biopolymer nanoparticle latex and a
multifunctional crosslinking agent for use in the formation of
mineral, natural organic, or synthetic fiber products, including
mineral fiber insulation, non-woven mats, fiberglass insulation and
related glass fiber products. The fibers may comprise natural fiber
such as cellulose, sisal, wool, jute; synthetic fibers such as
polyolefins, polyesters, acrylics, nylon, polyamides, ceramics,
molten stone, stone wool, glass fibers, carbon fibers, aramid
fibers, and the like, alone or in combinations with one
another.
This specification describes a curable aqueous composition
comprising a biopolymer latex formulation comprising nanoparticles
of crosslinked starch and a multifunctional crosslinking agent.
FIG. 1 illustrates how the biopolymer nanoparticle 10 can be
thought of as one crosslinked macromolecular unit, with --R--
representing crosslinks between polymer molecules 12, for example
starch polymer molecules, located within the nanoparticle 10.
Whereas the biopolymer nanoparticles in the aqueous dispersion are
already internally crosslinked within the nanoparticles via
intra-particle crosslinks (see FIG. 1), an additional
multifunctional crosslinking agent may optionally be added to
facilitate interfacial inter-particle crosslinks (shown as R or X
in FIG. 2). Although crosslinking agents are inherently
multifunctional, the term multifunctional cross linking agent is
used herein to help avoid confusion with the crosslinking agent
used to form the nanoparticle. Said multifunctional crosslinking
agent is preferably designed to lie dormant, or at least to not
fully react, during the binder application stage and the fiber mat
formation and fluffing stages, but is triggered in the curing stage
by heat, an increasing solids content, or both, to react, or
further react, and lock in the desired fiber mat dimensions. The
multifunctional cross linking agent may further crosslink particles
to a reinforcement material such as fibers or wood in a non-fibrous
form, i.e. a form other than pulp. For example, TEOS has four
reaction sites. One or more of these reaction sites may bond with a
biopolymer nanoparticle before curing, but reactions at all four
sites, with other nanoparticles, a fiber or wood, are not believed
to occur until the composition is heated.
[0068] As indicated in FIG. 2, biopolymer nanoparticles 10 of the
type formed by cross linking essentially non-crystalline starch
molecules swell in water. The starch molecules are hydrophilic. At
low concentrations (ie. low volume fraction), for example at a
solids content of 20 wt % or less, the particles achieve a maximum
swelling value that is balanced between their elastic constraint
due to their crosslinked network and the osmotic pressure. The
maximum swelling value (or volume factor) of the particles may be
determined by measuring the relative viscosity, .eta..sub.r' of a
low concentration dispersion of the particles. The relative
viscosity (.eta..sub.r=.eta./.eta..sub.o) of the dispersion is
obtained by measuring the flow times between two demarcations of a
glass Ubbelohde viscometer for the dispersion (ii) and for its
dispersion medium (.eta..sub.o), which is water. Using the Einstein
equation, .eta..sub.r=1+2.5 f .phi., where f is the effective
volume factor and .phi. is the volume fraction, one can obtain the
effective volume factor (f) that is equal to the maximum volume
swelling of the particles at low concentrations. The effective
volume factors (i.e. the maximum volume swell ratios) of the
particles varies with different crosslink densities, for example
between about 6 and about 16. The Ecosphere 2202.TM. product has a
volume factor greater than 6.
[0069] The swelling occurs primarily in the core 14 (see FIG. 1) of
the particle. The shell 16 (see FIG. 1) provides a steric
stabilization mechanism that enhances the colloid forming nature of
the particles.
[0070] The particles de-swell to some extent when solids
concentration increases, as occurs when water is evaporated out of
a dispersion during heat curing, so that their dispersions can be
made at higher solids, as shown in FIG. 1. In particular,
de-swelling will take place when the concentration of the
dispersion exceeds that of the starch network in the nanoparticles
which is equal to the reciprocal 1/SR(W) of the weight swell ratio,
SR(W). For example, if SR(W) is 5, then starch nanoparticles will
start de-swelling when the concentration of a crosslinked starch
dispersion approaches or exceeds 20% solids.
[0071] Internal crosslinking in the particles prevents them from
de-swelling completely and so the particles can be described as a
hydrogel. When dried during curing, crosslinked starch based
particles have a density less than the density of a native starch
granule. For example, a native starch granule may have a relative
density of about 1.6 whereas a crosslinked starch particle may have
a relative density of about 1.0. While this hydrogel nature of
certain particles may not be required in all applications, it is
advantageous in at least some applications.
[0072] In general, the cost and energy required to produce a
material varies with its weight. However, the ability of the
particles to function as a binder is related to their volume.
Accordingly, a less dense particle can provide a more efficient use
of material, and a lighter finished product. Further, in the case
of insulating products, the rate of heat transfer tends to decrease
with density and so a hydrogel form of a material may provide
better thermal performance in an insulation product.
[0073] In the case of an insulation product, the hydrogel nature of
some particles is also well adapted to standard fiberglass
insulation production methods. In stage 1 (see FIG. 2) the
dispersion is free flowing, and may be applied by sprayers
typically used in fiberglass insulation making. Stage 2 may be
viewed as covering the time from when the spray contacts the fibers
to when fiber temperature begins to rise again when the fiber matt
enters Stage 3. During stage 2, some water evaporates and the
dispersion reaches a solids concentration in which the particles
contact each other. The dispersion then becomes film forming but is
still flowable and tends to accumulate at binding locations such as
intersections between fibers where the fibers contact each other or
come close to contacting each other. During stage 3, as the
particles de-swell towards their maximum density, they become
immobile around intersections between fibers and so bind the fibers
together.
[0074] FIG. 3 illustrates a schematic of a cured product 20 made
with mineral, natural organic, or synthetic fibers 22 bound with
biopolymer nanoparticles 12. The product has effective chamber
formation that results from the curable aqueous composition, for
example a composition comprising biopolymer nanoparticles, for
example a biopolymer latex formulation comprising nanoparticles of
crosslinked starch and a multifunctional crosslinking agent.
Effective chamber formation is important in fiberglass
manufacturing in order to provide acceptable insulation, fiber mat
strength, compactability and recovery properties.
[0075] FIG. 4 provides an SEM micrograph (at 500.times.
magnification) of a non-woven mat of glass fibers 32 to which a
biopolymer latex formulation comprising nanoparticles of
crosslinked starch and a multifunctional crosslinking agent has
been added following which it was cured. Binding locations 32
comprising cured products of the formulation are visible at fiber
intersections.
[0076] FIG. 5 is an SEM micrograph of a glass fiber 32 mat to which
a biopolymer latex formulation comprising nanoparticles of
crosslinked starch and a multifunctional crosslinking agent has
been added following which it was cured, and this higher resolution
SEM micrograph (at 2,500.times. magnification) serves to illustrate
extensive interfiber "spot welding", or fiber to fiber bonding, at
binding locations 30 with the biopolymer latex
binder/multifunctional crosslinker composition. FIG. 6 is a high
resolution SEM micrograph at 30,000.times. of a spot weld, or fiber
to fiber bond, area within a binding location 30 in a fiber mat
cured with a binder composition consisting of 50% polyacrylic acid
(PAA)-50% biopolymer latex, by weight of PAA and biopolymer
nanoparticles, binder composition containing a multifunctional
crosslinker. The biopolymer nanoparticles 12 are clearly visible in
the high resolution micrograph depicted in FIG. 6, that is at least
those located at or near the surface of the cured polymer
blend.
[0077] The high surface area of the biopolymer nanoparticles in the
aqueous dispersion, an in particular a biopolymer latex, in itself
provides bonding for mineral fibers while the additional
multifunctional crosslinking agent facilitates interfacial
inter-particle crosslinks, and/or crosslinks to the fibers. The
bonding provides fiber mat recovery when used to make insulation
products and dry and wet tensile strength sufficient for various
products, such as asphalt shingles.
Biopolymer nanoparticles can be formed as prescribed in U.S. Pat.
No. 6,677,386 (which corresponds to International Publication WO
00/69916). In that process, a biopolymer, such a starch comprising
amylose or amylopectin or both, is combined with a plasticizer.
This combination is mixed under high shear forces, preferably in a
twin screw fully intermeshing co-rotating extruder, to plasticize
the biopolymer and create a thermoplastic melt phase in which the
crystalline structure of the biopolymer is removed. A crosslinking
agent is then added while mixing continues to form cross-linked
nanoparticles. The nanoparticles exit the extruder as a strand,
which is ground to a fine dry powder. The starch based
nanoparticles are present in the powder in agglomerated form, and
can be dispersed in an aqueous medium.
[0078] The biopolymers may be starch or other polysaccharides such
as cellulose and gums, as well as proteins (e.g. gelatin, whey
protein). The biopolymers may be previously modified, e.g. with
cationic groups, carboxy-methyl groups, by acylation,
phosphorylation, hydroxyalkylation, oxidation and the like. Starch
and mixtures of at least 50% starch with other polymers are
preferred. The starting material may be a native or granular starch
selected from the group consisting of, for example, potatoes, rice,
tapioca, corn, peas, rye, oats, wheat, and combinations thereof.
The starch, whether used alone or in a mixture, is preferably a
high molecular weight starch, for example a molecular weight of at
least 10,000, and not dextran or dextrin. For example, the starch
may be made up of amylose or amylopectin or both. Waxy starches,
such as waxy corn starch, are particularly preferred.
[0079] The following five paragraphs are repeated or summarized
from U.S. Pat. No. 6,677,386 to further describe the process of
making the nanoparticles.
[0080] The biopolymer preferably has a dry substance content of at
least 50% by weight at the time when processing starts. Processing
is preferably done at a temperature of at least 40 degrees C., but
below the degredation temperature of the polymer, for example 200
degrees C. The shear can be effected by applying at least 100 J of
specific mechanical energy (SME) per g of biopolymer. Depending on
the processing apparatus used the minimum energy may be higher;
also when non-pregelatinised material is used, the minimum SME may
be higher, e.g. at least 250 J/g, especially at least 500 J/g.
[0081] The plasticiser may water or a polyol (ethyleneglycol,
propyleneglycol, polyglycols, glycerol, sugar alcohols, urea,
citric acid esters, etc.). The total amount of plasticisers (i.e.
water and others such as glycerol) is preferably between 15 and
50%. A lubricant, such as lecithin, other phospholipids or
monoglycerides, may also be present, e.g. at a level of 0.5-2.5% by
weight. An acid, preferably a solid or semi-solid organic acid,
such as maleic acid, citric acid, oxalic, lactic, gluconic acid, or
a carbohydrate-degrading enzyme, such as amylase, may be present at
a level of 0.01-5% by weight of biopolymer. The acid or enzyme
assists in slight depolymerisation which is assumed to be
advantageous in the process of producing nanoparticles of a
specific size.
[0082] The crosslinking is preferably reversible, i.e. the
crosslinks are partly or wholly cleaved after the mechanical
treatment step. Suitable reversible crosslinkers include those
which form chemical bonds at low water concentrations, which
dissociate or hydrolyse in the presence of higher water
concentrations. This mode of crosslinking results in a temporary
high viscosity during processing followed by a lower viscosity
after processing. Examples of reversible crosslinkers are
dialdehydes and polyaldehydes, which reversibly form hemiacetals,
acid anhydrides and mixed anhydrides (e.g. succinic and acetic
anhydride) and the like. Suitable dialdehydes and polyaldehydes are
glutaraldehyde, glyoxal, periodate-oxidised carbohydrates, and the
like. Glyoxal is a particularly suitable crosslinker.
[0083] Such crosslinkers may be used alone or as a mixture of
reversible crosslinkers, or as a mixture of reversible and
non-reversible crosslinkers. Thus, conventional crosslinkers such
as epichlorohydrin and other epoxides, triphosphates, divinyl
sulphone, can be used as non-reversible crosslinkers for
polysaccharide biopolymers, while dialdehydes, thiol reagents and
the like may be used for proteinaceous biopolymers. The
crosslinking reaction may be acid- or base-catalysed. The level of
crosslinking agent can conveniently be between 0.1 and 10 weight %
with respect to the biopolymer. The crosslinking agent may already
be present at the start of the mechanical treatment, but in case of
a non-pre-gelatinised biopolymer such as granular starch, it is
preferred that the crosslinking agent is added later on, i.e.
during the mechanical treatment.
[0084] The mechanically treated, crosslinked biopolymer is then
formed into a latex by dispersion in a suitable solvent, usually
water and/or another hydroxylic solvent such as an alcohol), to a
concentration of between 4 and 50 weight % especially between 10
and 40 wt. %. Prior to the dispersion a cryogenic grinding step may
be performed, but stirring with mild heating may work equally well.
This treatment results in a gel which either spontaneously or after
induction by water adsorption, is broken into a latex. This
viscosity behaviour can be utilised for applications of the
particles, such as improved mixing, etc. If desired, the dispersed
biopolymer may be further crosslinked, using the same or other
crosslinking agents as describe above. The extrudate is
characterised by swelling in an aqueous solvent, e.g. water or a
mixture of at least 50% water with a water-miscible solvent such as
an alcohol, and by exhibiting a viscosity drop afterwards to
produce a dispersion of nanoparticles.
[0085] International Patent Application Publication No. WO
2008/022127 A2 and its equivalent US Patent Application Publication
Number 2011/0042841 A1 describe a process for producing biopolymer
nanoparticles in large quantities. US Patent Application
Publication Numbers 2010/0143738 A1 describes a process for
producing biopolymer nanoparticles conjugative with additives
during the extrusion process. These publications are incorporated
by reference.
[0086] The production of biopolymer nanoparticles similarly formed
by reactive extrusion and comprising starch essentially without
crystalline structures is described in Starch nanoparticle
formation via reactive extrusion and related mechanism study,
Delong Song et al., Carbohydrate Polymers 85 (2011) 208-214. Using
various materials and reaction conditions, dispersions having
particles with number average particle sizes up to about 2000 nm
were produced.
[0087] Another method of producing biopolymer nanoparticles by
reactive extrusion process from waxy corn starch is described in
International Publication Number WO 2011/071742 A2, Process for
Preparing Stable Starch Dispersions, by Welsch et al., published on
Jun. 16, 2011. This process comprises introducing a feed starch and
an hydroxylc liquid to an extruder. Shear forces are applied in the
extruder to the starch and the liquid in the substantial absence of
a cross-linker under conditions sufficient to prepare a stable
dispersion of starch particles in the hydroxylic liquid.
[0088] Another method of producing biopolymer nanoparticles is
described in International Publication Number WO 2011/155979 A2,
Process for Preparing Stable Dispersions of Starch Particles, by
Welsch et al., published on Dec. 15, 2011. In this process, a feed
starch and an aqueous liquid are introduced into a rotor stator
mixer. The feed starch and aqueous liquid are maintained in the
rotor stator mixer at a temperature ranging from a gelation
temperature to less than a solubilization temperature. The feed
starch is sheared into starch particles with the rotor static mixer
to form the dispersion of starch particles in the aqueous
liquid.
[0089] Another method of producing a starch nanoparticle is
described in U.S. Pat. No. 6,755,915 to Van Soest et al. (Jun. 29,
2004) which teaches a method of preparing starch particles with a
size range of 50 nm to 100 im. The method includes the steps of:
dispersing starch in a first water phase; dispersing a second
hydrophobic phase in the first phase to form an oil-in-water
emulsion; inverting the oil-in-water emulsion to a water-in-oil
emulsion; cross-linking the starch in the first phase; and
separating the formed starch particles. The phase inversion can
occur by including a surfactant that stabilizes a water-in-oil
emulsion or the surfactant can be temperature sensitive and
increasing the reaction temperature. The inversion can also occur
by the addition of further hydrophobic liquids or various suitable
salts. In this process the starch molecules can remain partially
granular during both the cross-linking reaction and complete
gelatinisation of the granular starch can be effected before,
during or after the phase inversion. Gelatinization occurs by
increased temperature, salts or combinations thereof.
[0090] Another method of making biopolymer nanoparticles is
described in WO 2010/084088 to Santander Ortegea et al.
(international publication Jul. 29, 2010). The method includes the
steps of preparing starch derivatives by a first disintegration
step, with solvent and increased temperatures, followed by common
substitution methods, such as esterification, etherification. The
starch derivatives are added to an organic solvent and an oil/water
emulsion is prepared with a high shear mixer. Sonication may be
used to improve the oil droplet distribution. The organic phase is
then removed through a membrane, which results in an aqueous
dispersion of starch-based nanoparticles.
[0091] Another method of making biopolymer nanoparticles is
described in GB 1,420, 392 to Beersma which teaches a method of
forming starch particles by cross-linking native starch granules
and then fragmenting the cross-linked starch granules with heat and
pressure in an extruder.
[0092] Another method of making biopolymer nanoparticles is
described in WO 2010/065750 to Bloembergen et al. which teaches
that Brabender static high shear mixers and Sigma Blade mixers may
be used in place of an extruder to produce nanoparticles by way of
shearing starch granules in the presence of a crosslinker.
[0093] The nanoparticles may form a colloid or latex in water. The
particles may be made up of water-swollen crosslinked hydrophilic
polymers. The polymers may have hydroxyl functional groups. The
particles may swell by an effective volume factor (maximum volume
swell ratio in water) of 6 or more, but de-swell at increasing
solids content, for example when water is evaporated from them by
heat while curing.
[0094] The binder composition may include as the multifunctional
crosslinking agent polyacids having at least two acidic functional
groups that will react with the alcohol moieties on the starch
particles. It is preferred to use nonpolymeric polyacids. These
nonpolymeric polyacids include at least one of citric acid, maleic
acid, succinic acid, phthalic acid, glutaric acid, malic acid,
phthalic acid or the like, and salts thereof.
[0095] The binder composition may include as the multifunctional
crosslinking agent an anhydride of the nonpolymeric polyacid. These
anhydrides include at least one of maleic anhydride, succinic
anhydride, phthalic anhydride and the like.
[0096] The binder composition may contain as a plasticizer and/or
processing aid a polyol of a wide variety of materials, including,
but not limited to, ethylene glycol (to make 2,3-dihydroxydioxane),
diethylene glycol, dialkylene glycol (to make an oligomeric
condensation product) such as 1,2-propylene glycol, 1,3-propylene
glycol, 1,2-butylene glycol, 1,3-butylene glycol, 1,4-butylene
glycol, polyethylene glycols having the formula
HO(CH.sub.2CH.sub.2O).sub.nH where n is 1 to about 50, silanols (as
products of hydrolysis of organosiloxanes), and the like, and their
mixtures. Other suitable polyols (i.e. containing at least three
hydroxy groups) can be used, such as glycerin, (to make
2,3-dihydroxy-5-hydroxymethyl dioxane) as well as unalkylated or
partially alkylated polymeric glyoxal derived glycols such as
poly(N-1',2'-dihydroxyethyl-ethylene urea), dextrans, glyceryl
monostearate, ascorbic acid, erythrobic acid, sorbic acid, ascorbyl
palmitate, calcium ascorbate, calcium sorbate, potassium sorbate,
sodium ascorbate, sodium sorbate, monoglycerides of edible fats or
oils or edible fat-forming acids, inositol, sodium tartrate, sodium
potassium tartrate, glycerol monocaprate, sorbose monoglyceride
citrate, polyvinyl alcohol, .alpha.-D-methylglucoside, sorbitol,
dextrose, and their mixtures.
[0097] The binder, alternatively called a curable aqueous
composition, is prepared in one form of biopolymer nanoparticles
and a multifunctional crosslinker. The biopolymer nanoparticles are
dispersed in water and/or hydroxylic solvent (such as an alcohol),
to a concentration of biopolymer nanoparticles of between 4 and 50
wt %, or between 10 and 20 wt %, prior to curing, usually at the
application site where it is combined with the fibers and then
cured. Optionally, the binder may also contain, or be mixed with,
other binders, alternatively called resins or aqueous curable
compositions, know in the art (for example the binders described in
the background section herein) or other binders, known now or
developed in the future, useful for binding fibers or wood
together. Optionally, the binder or curable aqueous composition may
contain a multifunctional crosslinker or other additives.
Optionally, the binder may contain another latex, for example an SB
latex, or an extender. The curable aqueous composition may provide
a partial or complete replacement for a formaldehyde-based binder
or polymer binder, or a latex component of a binder system. The
curable aqueous composition may be used in combination with a
formaldehyde-based binder or other petro-chemical based soluble
polymer or latex component of a binder system. A formaldehyde free
binder system may be made by using the curable aqueous composition
alone or in combination with a non-formaldehyde binder system,
which may be an organic, for example petro-chemical based, system
such as one using polyacrylic amide (PAA) or polyester (PE) resins,
or a biopolymer system using, for example, a soluble protein,
starches, dextrin or other biopolymer.
[0098] One method for forming a non-woven material comprises:
mixing fibers with a binder, and heating the binder and fibers at
130.degree. C. to 230.degree. C. for sufficient time to cure.
Preferably, the binder comprises up to 95% by weight of water
immediately prior to curing. Most preferably, the binder comprises
85 to 95% by weight of water immediately prior to curing. The
binder and fibers can also be heated at 180.degree. C. to
220.degree. C. for sufficient time to cure.
[0099] A biopolymer latex is substantially water-dilutable. The
binder can be mixed with the nonwoven fiber material by spraying,
soaking or other suitable methods commonly used by the industry.
The material is then dried and the binder is cured in an oven at
elevated temperatures, generally at 130.degree. C. to 230.degree.
C. providing for the formation of a rigid thermoset polymer.
[0100] The curable aqueous composition may includes other
components, e.g., emulsifiers, plasticizers, anti-foaming agents,
biocide additives, anti-mycosis including, e.g., fungicides and
mold inhibitors, adhesion promoting agents, colorants, waxes,
antioxidants, and combinations thereof.
[0101] The curable aqueous composition can be used to prepare
nonwoven products by a variety of methods known in the art, which,
in one embodiment, involves the impregnation of a loosely assembled
mass of fibers with the binder solution to form a mat. The fibers
may comprise natural fiber such as cellulose, sisal, wool, jute;
synthetic fibers such as polyolefins, polyesters, acrylics, nylon,
polyamides, ceramics, molten stone, stone wool, glass fibers,
carbon fibers, aramid fibers, and the like, alone or in
combinations with one another. The product may be used, for
example, in building insulation, a roofing fiberglass mat,
construction materials, or a nonwoven filtration material.
[0102] In various trials, fiberglass insulation batts were made
using binder compositions comprising a blend of 100 parts EcoSphere
2202 starch based biopolymer nanoparticles with an average size of
less than 400 nm, 100 parts of a second binder and 1 part of TEOS,
all parts on a dry solids basis. In different trials, PAA and
polyester (PE) were used as the second binder. The compositions
were used to manufacture a glass fiber insulation product on a
standard fiberglass bat manufacturing line. The binder was sprayed
onto glass fibers using high pressure nozzles already present in
the manufacturing line. The fibers were then collected, formed into
a mat, fluffed, and heated in an oven to the cure temperatures of
the binder mix. The cured glass fiber insulation samples had cured
binder contents between 3 and 10% by weight as determined by loss
on ignition (LOI); thicknesses of 70 to 300 mm; and, densities of 7
to 10 kg/m.sup.3. The binder content, thickness and densities were
varied to produce different grades (R values) of the resulting
insulation products. The product was then downsized to an
appropriate length and width, compressed and packaged in a bag. The
bats recovered their design thickness after the bags were
opened.
[0103] To make roofing shingles, mineral, natural organic, or
synthetic fibers, typically glass fibers, may be formed in a slurry
and placed on a support to form a mat. A curable aqueous
composition is coated on the mat, preferably wetting the mat. The
mat is then heated, for example between 130.degree. C. and
230.degree. C., for sufficient time to cure the curable aqueous
composition. The bonded mat is then coated with asphalt, or
bitumen. The curable aqueous composition may be mixed with a
formaldehyde based resin, for example with an adduct of
co-condensation of urea and formaldehyde, which may also function
as a multi-functional cross linker for the curable aqueous
composition. A petro-chemical latex may also be part of the
composition.
[0104] A curable aqueous composition can also be used to prepare
wood based products such as particle board, plywood and oriented
strand board (OSB) products. These products may be made, for
example, from wood in a non-fibrous form, ie. a form other than
pulp, such as wood chips, sawmill shavings, saw dust, wood veneers,
wood strips, and mixtures thereof. In making particle board, wood
particles, such as wood chips, sawmill shavings, or saw dust, are
mixed with the curable aqueous composition. Once the composition
has been mixed with the particles, the mixture is made into a
sheet. The sheets formed are then cold-compressed to reduce their
thickness, and later they are compressed again, under pressures
(e.g., between two and three megapascals) and temperatures between
about 130.degree. C. and 230.degree. C. In making plywood, the
curable aqueous composition is placed between wood veneers to form
a sheet, and the sheets are compressed under pressure and
temperatures between about 130.degree. C. and 230.degree. C. In
making OSB, wood is shredded into strips, which are then oriented
on a belt to make a mat. The mat is placed in a thermal press to
compress the strips and bond them by heat activation at between
about 130.degree. C. and 230.degree. C. to cure the curable aqueous
composition that has been coated on the strips.
[0105] Optionally, a curable aqueous composition comprises a
biopolymer nanoparticle latex and a multifunctional crosslinking
agent. The composition may be used in the formation of mineral,
natural organic, or synthetic fiber products, including mineral
fiber insulation, non-woven mats, fiberglass insulation and related
glass fiber products. A curable aqueous composition may also be
used in combination with another binder, including a
non-formaldehyde binder such as PAA or PE.
EXAMPLES
[0106] The following Examples and are not intended to limit the
claims.
Example 1
Preparation of Biopolymer Binder Composition
[0107] The technique described in U.S. Pat. No. 6,677,386 has been
used to prepare biopolymer nanoparticles by reactive extrusion
processing. Native potato starch, corn starch, tapioca and waxy
corn starch have been used to prepare nanoparticles. Agglomerated
particles of such nanoparticles are commercially available, sold
under the trade mark Ecosphere, from Ecosynthetix Inc. Ecosphere
2202 extruded pellets comprised of starch nanoparticles were
dispersed in water using mechanical agitation. The nanoparticles at
35% (w/v) solids were dispersed in 15 minutes at 45.degree. C.
using a 3-blade mixer at 200 rpm. A crosslinker (tetraethyl
orthosilicate) was added in amount of 1 wt % (based on dry solids)
and mixed for 30 minutes. After that the pH was adjusted to 7.0
with aqua ammonia. The binder is a low viscosity liquid. The
stability of the resulting biopolymer binder is about 1 month at
room temperature.
Example 2
Preparation of Blends of Biopolymer Binder
[0108] Glass fiber binder compositions were prepared using the
biopolymer of Example 1 mixed with 25, 40 and 50 parts (dry basis)
of polyester as described in example 3 of WO 03/106561 at room
temperature. A crosslinker (tetraethyl orthosilicate) was added in
the amount of 1% by weight (based on dry solids) and mixed for 30
minutes. No crosslinker was added to the control binder
compositions. After that the pH was adjusted to 7.0 with aqua
ammonia. In addition, a glass fiber binder composition was prepared
using the biopolymer of Example 1 mixed with 50 parts (dry basis)
of polyacrylic binder as described in the example of U.S. Pat. No.
6,331,350 at room temperature. A crosslinker (tetraethyl
orthosilicate) was added in the amount of 1% wt (based on dry
solids) and mixed for 30 minutes. After that the pH was adjusted to
7.0 with aqua ammonia. No crosslinker was added to the control
binder composition.
Example 3
Tensile Testing of Cured Glass Fiber Specimens
[0109] The biopolymer binder composition of Example 1 prepared from
dry EcoSphere.RTM. 2202 biopolymer latex powder to give a 35%
solids dispersions was subsequently diluted with water to give a
binder dispersion having 15% non-volatiles, and the binder solution
was applied to a glass fiber substrate as follows. Glass paper
(Whatman 934-AH) was soaked in the binder solution for 5 minutes,
then the excess liquid was removed by vacuum. The samples were put
into an oven at 200.degree. C. for 5 minutes for curing of the
binder resin. The cured samples were cut into specimens having the
dimensions of 6''.times.1'' and tested for dry tensile strength by
an Instron tensile tester. For wet tensile testing, the specimens
were treated with hot water at 80.degree. C. for 10 minutes, and
then tested for tensile strength while still wet. The test results
are presented in the Table 1, where Comparative A is polyester
binder as described in WO 03/106561; comparative B is a pure
polyacrylic binder at 15% solids as described in U.S. Pat. No.
6,331,350; C is a pure biopolymer nanoparticle biopolymer latex
binder dispersion at 15% solids (based on EcoSphere.RTM. 2202
biopolymer latex binder); C* is as C, but with 1% of tetraethyl
orthosilicate (TEOS) crosslinker added; D is a 40/60 blend of A and
C; D* is a 40/60 blend of A and C* (with 1% TEOS crosslinker
added); E is a 25/75 blend of A and C; F is a 50/50 blend of A and
C; G is a 50/50 blend of B and C; and G* is a 50/50 blend of B and
C* (with 1% TEOS crosslinker added).
TABLE-US-00001 TABLE 1 Tensile Strength of Nonwovens Crosslinker
Dry strength, Wet strength, Retention, Binder Added kgf kgf %
Comparative No 35.1 18.4 52.4 A Comparative No 25.9 17.3 66.8 B C
No 19.4 3.5 18.0 C* Yes 18.4 9.5 51.3 D No 24.0 17.1 71.3 D* Yes
26.6 22.3 83.8 E No 24.4 15.6 63.9 F No 24.8 17.9 72.2 G No 28.9
16.1 55.7 G* Yes 28.7 22.2 77.5
[0110] The results indicate that addition of a small amount of a
multifunctional crosslinker, such as the TEOS silane crosslinker
(0.5 to 1.5 wt %, dry basis), significantly improves the wet
strength of the fiber mat and the Retention, a key performance
attribute. The Retention was calculated as a ratio of Wet
Strength/Dry Strength in percent. The tensile strength was measured
as the maximum load in kgf at break.
Example 4
UF-Biopolymer Latex Binder Preparation
[0111] A resin of 60% solids, having a formaldehyde-urea mole ratio
of 1.65:1, and having a final viscosity of "O" on the Gardner-Holdt
scale was prepared. A stirred reactor was charged with the required
quantities of 50 wt % aqueous formaldehyde solution (formalin),
urea and nano-starch EcoSphere.RTM. 2202 biopolymer latex binder at
15% solids. After an initial 15-minute reflux, the pH was adjusted
to 6.5 with formic acid and then the reflux was continued to the
desired viscosity ("O" on the Gardner-Holdt scale). The pH was then
was adjusted to 7.5 with 28% ammonium-hydroxide and the resin
solution was concentrated to 60% solids by vacuum distillation. A
comparative UF resin containing an additive comprising
poly(styrene-co-methacrylic acid) was prepared without the addition
of nano-starch, as described in U.S. Pat. No. 6,642,299.
Example 5
Treatment of Nonwovens and Tensile Testing of Treated Nonwovens
[0112] The binder compositions of Example 4 were applied to a glass
fiber specimen (Whatman 934-AH) by saturation method and the excess
binder was recovered by vacuum, and the specimen was then cured in
the oven at 200.degree. C. for 5 minutes. The binder add-on was
28%.+-.2% (dry binder weight based on the weight of glass). The
testing procedure is described in Example 3. The test results are
presented in Table 2 where Comparative H contains urea-formaldehyde
resin modified with an additive comprising
poly(styrene-co-methacrylic acid); J contains urea-formaldehyde
resin that was first prepared and then modified with an additive
comprising EcoSphere.RTM. (Post-added); K contains
urea-formaldehyde resin that was modified in the presence of an
additive comprising EcoSphere.RTM. (Cooked-in).
TABLE-US-00002 TABLE 2 Tensile Testing of Treated Nonwovens Dry Wet
Biopolymer Shelf Life Tensile Tensile Retention, Sample latex
Binder Stability (kgf) (kgf) % Comparative None 3-5 hrs 5.71 5.64
98.7 H J Post-added 3 weeks 4.52 3.84 84.9 K Cooked-in >3 months
5.48 4.7 85.8
[0113] By "Post-added" we mean blending of a certain amount of
biopolymer latex binder with previously cooked urea-formaldehyde
polymer resin; by "Cooked-in" we mean addition of the biopolymer
latex binder during the polymerization of urea and
formaldehyde.
[0114] In Example 5 (for both samples J and K), where the synthetic
polystyrene acrylic acid was 100% replaced on a one-for-one basis,
the urea-formaldehyde in the composition provides the
multifunctional crosslinker for the biopolymer latex binder. The
relative performance is illustrated by comparing the control sample
H to sample J (post-added) and K (cooked-in). Sample K provides
sufficient tensile strength and Retention to serve as a suitable
binder system for non-woven fiber mats used in roofing shingles.
The significant advantage is that this binder composition has much
improved stability and much longer shelf life, whereas the
conventional UF-polystyrene acrylic acid binder system requires to
be pre-mixed right before application. This poor shelf life
stability causes waste and requires added manpower and cost for
ongoing and frequent batch preparations.
Example 6
Replacement of SB Latex in Roofing Shingle Binder
[0115] Fiberglass asphalt shingles are made of a dense fiberglass
mat bonded with urea-formaldehyde resin and then coated with
asphalt. SB latex has been added to the urea formaldehyde resins,
for example to increase the flexibility of the shingle. A
comparative binder was made of a UF resin with 5 wt % SB latex on a
dry solids basis. Experimental samples were made with a) a mixture
of UF resin and 5 wt % on a dry slids basis of Ecosphere.TM. 2202
crosslinked starch nanoparticles, b) a mixture of 5 wt % on a dry
solids basis of SB latex and Ecosphere 2202 particles at a 1:3
ratio and c) 5 wt % on a dry solids basis of Ecosphere 2202
particles "Cooked-in", meaning added during the polymerization of
urea and formaldehyde. Test strips were made and tested for tensile
strength as described in Example 5. The dry and wet tensile
strength results are presented in Table 3. As shown in Table 3, the
tensile strengths of all of the samples tested were adequate for
use in fiberglass shingles. The SB latex mixture had a short shelf
life whereas the Ecosphere mixtures can be expected based on the
results in Example 5 to have a significantly longer shelf life.
TABLE-US-00003 TABLE 3 Tensile Testing of Wet Laid Glass Fiber Mat
Max Load Max Load Retention Sample Dry (kgF) Wet (kgF) % UF with 5%
of SB 33.3 28.0 84.1 UF with 5% of 25.8 24.2 94.1 Ecosynthetix 2202
UF with SB/Eco 1:3 32.9 28.1 85.5 UF with 5% of 34.3 28.0 81.7
Ecosynthetix 2202 cooked in
Example 7
Binders with Varying Amounts of Crosslinker
[0116] Sample binder compositions were prepared as described in
Example 1 but with different amounts of the TEOS crosslinker. In
particular, compositions having 0 wt %, 0.5 wt %, 1.0 wt %, 3.0 wt
% and 5.0 wt % TEOS based on dry solids were prepared. The binder
compositions were tested for wet and dry tensile strength using the
method described in Example 3 except that a 1 kN load cell was used
in the Instron tensile tester instead of the 5 kN load cell used in
Example 3. The 1 kN load cell is believed to provided more accurate
results. The tensile strength results are presented in Table 4. All
of the amounts of cross linker tested showed improvements in dry
and wet strength over the composition without cross linker.
TABLE-US-00004 TABLE 4 Tensile Strength of Binders with Different
Amounts of Crosslinker Dry Wet Wt % TEOS strength (max strength
(max Retention crosslinker load in KgF) load in KgF) (%) 0.0 50.1
7.5 14.9 0.5 62.9 28.8 45.7 1.0 66.1 30.6 46.3 3.0 61.3 22.3 36.3
5.0 57.4 22.9 40.0
Example 8
Binders with Different Crosslinkers
[0117] Sample binder compositions were prepared as described in
Example 1 but with different crosslinkers. In particular,
compositions having 1 wt % TEOS, 3 wt % Ca metasilicate, 1 wt % Ca
metasilicate and 1 wt % Na metasilicate based on dry solids were
prepared. The binder compositions were tested for wet and dry
tensile strength using the method described in Example 3 except
that al kN load cell was used in the Instron tensile tester instead
of the 5 kN load cell used in Example 3. The 1 kN load cell is
believed to provided more accurate results. The tensile strength
results are presented in Table 5.
TABLE-US-00005 TABLE 5 Tensile Strength of Binders with Different
Crosslinkers Dry Wet strength (max strength (max Retention
Crosslinker load in KgF) load in KgF) (%) 1 wt % TEOS 64.9 50.9
78.3 3 wt % Ca metasilicate 61.4 47.6 77.4 1 wt % Ca metasilicate
61.3 37.6 61.3 1 wt % Na metasilicate 65.3 37.3 57.1
[0118] Thus, the invention provides a curable composition for
forming a composite material wherein the composition includes a
biopolymer nanoparticle latex including crosslinked nanoparticles,
and a multifunctional crosslinking agent for forming a cured
crosslinked binder joining a portion of a plurality of
reinforcement fibers in the composite material.
[0119] Although the present invention has been described in detail
with reference to certain embodiments, one skilled in the art will
appreciate that the present invention can be practiced by other
than the described embodiments, which have been presented for
purposes of illustration and not of limitation. Therefore, the
scope of the appended claims should not be limited to the
description of the embodiments contained herein.
* * * * *
References