U.S. patent application number 14/334731 was filed with the patent office on 2014-11-20 for formaldehyde free binder compositions with urea-aldehyde reaction products.
The applicant listed for this patent is JOHNS MANVILLE. Invention is credited to Kiarash Alavi.
Application Number | 20140342627 14/334731 |
Document ID | / |
Family ID | 51896126 |
Filed Date | 2014-11-20 |
United States Patent
Application |
20140342627 |
Kind Code |
A1 |
Alavi; Kiarash |
November 20, 2014 |
FORMALDEHYDE FREE BINDER COMPOSITIONS WITH UREA-ALDEHYDE REACTION
PRODUCTS
Abstract
Fiber-containing composites are described that contain woven or
non-woven fibers, and a cured binder formed from a binder
composition that includes (1) a reducing sugar and (2) a
crosslinking agent that includes a reaction product of a urea
compound and a polycarbonyl compound. Exemplary reaction products
for the crosslinking agent may include the reaction product of urea
and an .alpha.,.beta.-bicarbonyl compound or an
.alpha.,.gamma.-bicarbonyl compound. Exemplary fiber-containing
composites may include fiberglass insulation.
Inventors: |
Alavi; Kiarash; (Littleton,
CO) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
JOHNS MANVILLE |
Denver |
CO |
US |
|
|
Family ID: |
51896126 |
Appl. No.: |
14/334731 |
Filed: |
July 18, 2014 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
13490638 |
Jun 7, 2012 |
|
|
|
14334731 |
|
|
|
|
Current U.S.
Class: |
442/181 ;
442/327 |
Current CPC
Class: |
C08L 1/02 20130101; D04H
1/64 20130101; C08L 3/02 20130101; Y10T 442/30 20150401; D06M 15/05
20130101; Y10T 442/60 20150401; D04H 1/587 20130101 |
Class at
Publication: |
442/181 ;
442/327 |
International
Class: |
D06M 15/05 20060101
D06M015/05 |
Claims
1. A fiber-containing composite comprising: woven or non-woven
fibers; and a cured binder formed from a binder composition
comprising: reducing sugar; and a crosslinking agent comprising a
reaction product of a urea compound and an polycarbonyl compound,
wherein the reaction product is the exclusive crosslinking agent
for the reducing sugar.
2. The fiber-containing composite of claim 1, wherein the fibers
include one or more types of fibers chosen from glass fibers,
mineral fibers, and organic polymer fibers.
3. The fiber-containing composite of claim 1, wherein the reducing
sugar is chosen from glucose, dextrose, fructose, maltose, xylose,
and amylose.
4. The fiber-containing composite of claim 1, wherein the reducing
sugar comprises dextrose.
5. The fiber-containing composite of claim 1, wherein the urea
compound comprises H.sub.2N--CO--NH.sub.2.
6. The fiber-containing composite of claim 1, wherein the urea
compound has the formula: ##STR00017## wherein R.sub.1, R.sub.2,
R.sub.3, and R.sub.4 are independently chosen from a hydrogen
moiety (H), an alkyl group, an aromatic group, an alcohol group, an
aldehyde group, a ketone group, a carboxylic acid group, and an
alkoxy group.
7. The fiber-containing composite of claim 1, wherein the
polycarbonyl compound comprises an .alpha.,.beta.-bicarbonyl
compound or an .alpha.,.gamma.-bicarbonyl compound.
8. The fiber-containing composite of claim 7, wherein the
.alpha.,.beta.-bicarbonyl compound has the formula: ##STR00018##
wherein R.sub.5 and R.sub.6 are independently chosen from a
hydrogen moiety (H), an alkyl group, or an aromatic group.
9. The fiber-containing composite of claim 7, wherein the
.alpha.,.beta.-carbonyl compounds include gloxyal, diacetyl, and
benzil (i.e., 1,2-diphenylethane-1,2-dione).
10. The fiber-containing composite of claim 7, wherein the
.alpha.,.gamma.-bicarbonyl compound has the formula: ##STR00019##
wherein R.sub.7 and R.sub.9 are independently chosen from a
hydrogen moiety (H), an alkyl group, or an aromatic group.
11. The fiber-containing composite of claim 7, wherein the
.alpha.,.gamma.-bicarbonyl compound has the formula: ##STR00020##
wherein R.sub.9 and R.sub.10 are independently an alkyl group or an
aromatic group.
12. The fiber-containing composite of claim 7, wherein the
.alpha.,.gamma.-bicarbonyl compound has the formula: ##STR00021##
wherein R' and R'' are independently a hydrogen moiety (H) or an
alkyl group.
13. The fiber-containing composite of claim 7, wherein the
.alpha.,.gamma.-bicarbonyl compound has the formula: ##STR00022##
wherein R represents an alkyl group.
14. The fiber-containing composite of claim 1, wherein the
polycarbonyl compound comprises at least one aldehyde group and at
least one ketone group.
15. The fiber-containing composite of claim 1, wherein the reaction
product of the urea compound and the polycarbonyl compound is
chosen from the group of: ##STR00023##
16. The fiber-containing composite of claim 1, wherein the binder
composition further comprises a catalyst to catalyze a crosslinking
reaction between the reducing sugar and the reaction product of the
urea compound and the polycarbonyl compound.
17. The fiber-containing composite of claim 16, wherein the
catalyst is chosen from a Lewis acid, a protic acid and a latent
acid.
18. The fiber-containing composite of claim 17, wherein the Lewis
acid is chosen from aluminum sulfate, ferric sulfate, aluminum
chloride, ferric chloride, aluminum phosphate, and ferric
phosphate.
19. The fiber-containing composite of claim 17, wherein the protic
acid is chosen from sulfuric acid, phosphoric acid, hydrochloric
acid, nitric acid, toluene sulfonic acid, methane sulfonic acid,
and a carboxylic acid.
20. The fiber-containing composite of claim 17, wherein the latent
acid is chosen from ammonium sulfate, ammonium hydrogen sulfate,
monoammonium phosphate, diammonium phosphate, ammonium chloride,
and ammonium nitrate.
21. The fiber-containing composite of claim 16, wherein the
catalyst is an organo-metallic salt chosen from an organo-titanate
salt, an organo-zirconate salt, and organo-tin salt, and an
organo-aluminum salt.
22. The fiber-containing composite of claim 1, wherein the binder
composition further comprises one or more non-reducing
carbohydrates chosen from starch, modified starch, cellulose,
modified cellulose, and dextrins.
23. The fiber-containing composite of claim 1, wherein the
fiber-containing composite comprises a fiberglass building
insulation.
24. The fiber-containing composite of claim 1, wherein the binder
composition further comprises one or more additional compounds
chosen from polymerization catalysts, adhesion promoters, flame
retardants, organic fillers, inorganic fillers, waxes, colorants,
and release agents.
25. A fiber-containing composite comprising: woven or non-woven
fibers; and a cured binder formed from a binder composition
comprising: reducing sugar; and a crosslinking agent comprising a
reaction product of urea and an glyoxal, wherein a mole ratio of
the urea to the glyoxal is either (i) at least 2 moles of the urea
per 1 mole of the glyoxal, or (ii) 1 mole or less of the urea per 2
moles of the glyoxal.
26. The fiber-containing composite of claim 25, wherein the
reaction product is the exclusive crosslinking agent for the
reducing sugar.
27. The fiber-containing composite of claim 25, wherein the mole
ratio of the urea to the glyoxal is at least 2 moles of the urea
per 1 mole of the glyoxal, and wherein the reaction product
comprises a compound having formula: ##STR00024##
28. The fiber-containing composite of claim 25, wherein the mole
ratio of the urea to the glyoxal is at least 1 mole of the urea per
2 moles of the glyoxal, and wherein the reaction product comprises
a compound having formula: ##STR00025##
Description
CROSS-REFERENCES TO RELATED APPLICATIONS
[0001] This application is a continuation-in-part of prior U.S.
patent application Ser. No. 13/490,638, filed Jun. 7, 2012,
entitled "Formaldehyde Free Binder Compositions With Urea-Aldehyde
Reaction Products, (the "parent application") which is incorporated
herein by reference for all purposes.
BACKGROUND OF THE INVENTION
[0002] Organic binders for composite fiber products such as
fiberglass insulation are moving away from traditional
formaldehyde-based compositions. Formaldehyde is considered a
probable human carcinogen, as well as an irritant and allergen, and
its use is increasingly restricted in building products, textiles,
upholstery, and other materials. In response, binder compositions
have been developed that reduce or eliminate formaldehyde from the
binder composition.
[0003] One type of these formaldehyde-free binder compositions rely
on esterification reactions between carboxylic acid groups in
polycarboxy polymers and hydroxyl groups in alcohols. Water is the
main byproduct of these covalently crosslinked esters, which makes
these binders more environmentally benign, as compared to
traditional formaldehyde-based binders. However, these
formaldehyde-free binder compositions also make extensive use of
non-renewable, petroleum-based ingredients. Thus, there is a need
for formaldehyde-free binder compositions that rely less on
petroleum-based ingredient.
[0004] As an abundant and renewable material, carbohydrates have
great potential to be an alternative to petroleum-based binders.
Carbohydrates are already used as a component of some types for
binders, such as Maillard binders that contain reaction products of
reducing sugar carbohydrates and amine reactants. However, many
types of carbohydrate-containing binders tend to become brittle
when cured and form excessive particulates when the insulation is
folded or compressed. Some carbohydrate-containing binders are also
prone to accelerated degradation in humid environments and thus
require additional conditioning and additives to improve their
moisture/water resistance. Thus, there is a need to improve the
stability and water resistance of carbohydrate-containing binder
compositions to levels that are similar to or better than those of
conventional, petroleum-based binder compositions. These and other
issues are addressed in the present Application.
BRIEF SUMMARY OF THE INVENTION
[0005] Binder compositions are described that may include
carbohydrates and a crosslinking agent made from the reaction
product of a urea compound and an aldehyde-containing compound.
Examples of the crosslinking agents include imidazolidine compounds
made from the reaction product of urea (i.e.,
H.sub.2N--CO--NH.sub.2) and/or substituted ureas with
diformaldehyde compounds such as glyoxal. A specific example of an
imidazolidine crosslinking agent that may be used in the present
binder compositions is 4,5-dihydroxyimidazolidin-2-one, which has
the chemical structure:
##STR00001##
[0006] The binder composition may be applied to a group of fibers
to form an pre-cured amalgam of binder composition and fibers. The
amalgam may then be exposed to curing conditions (e.g., heating) to
facilitate the curing of the binder and formation of a
fiber-containing composite. During the curing stage, the
crosslinking agent crosslinks the reducing sugar to form a
polymeric matrix that adheres the fibers together in the
fiber-containing composite. Examples of these composites include
fiber insulation (e.g., fiberglass insulation) for piping, ducts,
buildings, and other construction applications.
[0007] Embodiments include binder compositions containing (1) a
reducing sugar and (2) a reaction product of a urea compound and an
aldehyde-containing compound. The binder composition may be applied
to a group of fibers and exposed to curing conditions to form a
fiber-containing composite of fibers bound by the cured binder.
[0008] A more specific embodiment of the binder composition may
include dextrose as the reducing sugar, and
4,5-dihydroxyimidazolidin-2-one as the reaction product of a urea
compound (in this case H.sub.2N--CO--NH.sub.2) and glyoxal
(OHC--CHO). When the dextrose and 4,5-dihydroxyimidazolidin-2-one
are exposed to binder curing conditions, the
4,5-dihydroxyimidazolidin-2-one crosslinks the dextrose (and
polymerized forms of dextrose) to make the cured binder.
[0009] Embodiments further include fiber-containing composites
containing woven or non-woven fibers and a cured binder formed from
a binder composition that includes (1) reducing sugar and (2) a
crosslinking agent that is a reaction product of a urea compound
and an aldehyde-containing compound. The fibers may be one or more
types of fibers chosen from glass fibers, mineral fibers, and
organic polymer fibers (among others). Non-woven glass fibers may
be included in composites for fiberglass insulation.
[0010] Embodiments still further include methods of binding fibers,
where the methods include the step of applying a binder composition
to a mat of woven or non-woven fibers, and then curing the binder
composition applied to the fibers to make a fiber-containing
composite. The binder composition may include a reducing sugar and
a crosslinking agent formed as a reaction product between a urea
compound and an aldehyde-containing compound, as described
above.
[0011] Additional embodiments and features are set forth in part in
the description that follows, and in part will become apparent to
those skilled in the art upon examination of the specification or
may be learned by the practice of the invention. The features and
advantages of the invention may be realized and attained by means
of the instrumentalities, combinations, and methods described in
the specification.
BRIEF DESCRIPTION OF THE DRAWINGS
[0012] A further understanding of the nature and advantages of the
present invention may be realized by reference to the remaining
portions of the specification and the drawings wherein like
reference numerals are used throughout the several drawings to
refer to similar components. In some instances, a sublabel is
associated with a reference numeral and follows a hyphen to denote
one of multiple similar components. When reference is made to a
reference numeral without specification to an existing sublabel, it
is intended to refer to all such multiple similar components.
[0013] FIG. 1 shows a graph of dogbone tensile strength test
results for different mole ratios of reducing sugar to crosslinking
agent;
[0014] FIGS. 2A-C show simplified illustrations of exemplary
composite materials according to embodiments of the invention;
[0015] FIG. 3 depicts a simplified schematic of an exemplary
fabrication system for making the fiber-containing composites
according to embodiments of the invention;
[0016] FIG. 4 is a picture of a cured dogbone composite placed in
an Instron tensile strength measuring instrument; and
[0017] FIG. 5 is a graph with dogbone tensile strength test results
for binder composites.
DETAILED DESCRIPTION OF THE INVENTION
[0018] The present binders include renewable materials such as
simple carbohydrates (e.g., dextrose, fructose) crosslinked by a
reaction product of (i) a urea compound with (ii) an aldehyde
and/or ketone containing compound. The urea compound may be a
substituted our unsubstituted urea having the Formula (I):
##STR00002##
where R.sub.1, R.sub.2, R.sub.3, and R.sub.4 are independently
chosen from a hydrogen moiety (H), an alkyl group, an aromatic
group, an alcohol group, an aldehyde group, a ketone group, a
carboxylic acid group, and an alkoxy group. Exemplary alkyl groups
include straight-chained, branched, or cyclic hydrocarbons of
varying size (e.g., C.sub.1-C.sub.12, C.sub.1-C.sub.8,
C.sub.1-C.sub.4, etc.). Exemplary aromatic (i.e., aryl) groups
include substituted or unsubstituted phenyl moieties, among other
aromatic constituents. Exemplary alcohol groups include --ROH,
where R may be a substituted or unsubstituted, saturated or
unsaturated, branched or unbranched, cyclic or acyclic, organic
moiety. For example, R may be --(CH2).sub.n-, where n may be 1 to
12. Exemplary alcohols may also include polyols having two or more
hydroxyl groups (--OH) in alcohol group. Exemplary aldehyde groups
include --RC(.dbd.O)H, where R may be a monovalent functional group
(e.g., a single bond), or a substituted or unsubstituted, saturated
or unsaturated, branched or unbranched, cyclic or acyclic, organic
moiety, such as --(CH2).sub.n-, where n may be 1 to 12. Exemplary
ketone groups may include --RC(.dbd.O)R' where R and R' can be
variety of carbon containing constituents. Exemplary carboxylic
acid groups may include --R--COOH, where R may be a monovalent
functional group, such as a single bond, or a variety of
carbon-containing constituents. Exemplary alkoxy groups include
--OR.sub.x, where R.sub.x is an alkyl group.
[0019] The aldehyde and/or ketone containing compounds may include
polyaldehydes (e.g., dialdehydes), polyketones (e.g., diketones),
and compounds that have at least one aldehyde group and at least
one ketone group. Examples include .alpha.,.beta.-bicarbonyl
compounds where carbonyl carbons are directly bonded as illustrated
in the following Formula (II):
##STR00003##
where R.sub.5 and R.sub.6 are independently chosen from a hydrogen
moiety (H), an alkyl group, or an aromatic group. Exemplary
.alpha.,.beta.-carbonyl compounds include gloxyal, diacetyl, and
benzil (i.e., 1,2-diphenylethane-1,2-dione).
[0020] Examples further include .alpha.,.gamma.-bicarbonyl
compounds where the carbonyl carbons are separated by one carbon
atom as illustrated in the following Formula (III):
##STR00004##
wherein R.sub.7 and R.sub.8 are independently chosen from a
hydrogen moiety (H), an alkyl group, or an aromatic group.
Exemplary .alpha.,.gamma.-bicarbonyl compounds include
malondialdehyde, and acetylacetone. In some instances, the R.sub.7
and R.sub.8 groups may independently also include alkoxide groups
(--OR) where R represents an alkyl group, and amine groups
(--NR'R''), where R' and R'' independently represent a hydrogen
moiety (H) or an alkyl group. For example, the
.alpha.,.gamma.-bicarbonyl compounds may include malonic acid
esters having Formula (IV):
##STR00005##
where R.sub.9 and R.sub.10 are independently an alkyl group or an
aromatic group.
[0021] Additional examples of .alpha.,.gamma.-bicarbonyl compounds
may include those with amide moieties such as those illustrated in
Formula (V):
##STR00006##
where R' and R'' are independently a hydrogen moiety (H) or an
alkyl group.
[0022] Additional examples of .alpha.,.gamma.-bicarbonyl compounds
may further include those with alkoxy moieties such as those
illustrated in Formula (VI):
##STR00007##
where R represents an alkyl group.
[0023] Exemplary aldehyde and/or ketone containing compounds may
include aldehyde-containing compounds having one or more (e.g., two
or more) aldehyde functional groups. Examples of these
aldehyde-containing compounds include acetaldehyde, propanaldehyde,
butyraldehyde, acrolein, furfural, glyoxal, gluteraldehyde, and
polyfurfural among others. Exemplary aldehyde-containing compounds
may also include substituted glyoxal compounds having Formula
(VII):
##STR00008##
where R.sub.11 and R.sub.12 may be independently hydrogen (H), an
alkyl group, an aromatic group, an alcohol group, an aldehyde
group, a ketone group, a carboxylic acid group, and an alkoxy
group, among other groups.
[0024] The reaction products of the urea compound and the aldehyde
and/or ketone containing compound depend on the types of compounds
selected, as well as the mole ratio of each compound. For example,
when the urea compound is urea and the aldehyde and/or ketone
containing compound is glyoxal in a 1:1 mole ratio, the predominant
reaction product is 4,5-dihydroxyimidazolidin-2-one represented by
Formula (VIII):
##STR00009##
[0025] However, when excess urea increases the mole ratio of
urea-to-glyoxal to 2:1, the predominant reaction product becomes a
glycoluril compound shown in Formula (IX):
##STR00010##
[0026] Alternatively, when excess glyoxal shifts the mole ratio of
urea-to-glyoxal to 1:2, the predominant reaction product becomes a
(2R,3S,6R)-2,3,5,6-tetrahydroxy-1,4-diazabicyclo[2.2.1]heptan-7-one
compound shown in Formula (X):
##STR00011##
[0027] The reaction products of the urea compound and an
aldehyde-containing compound having about a 1:1 mole ratio may
include imidazolidine compounds of the Formula (XI):
##STR00012##
where R.sub.13, R.sub.14, R.sub.15, and R.sub.16 are independently,
--H, --OH, --NH.sub.2, an alkyl group, an aromatic group, an
alcohol group, an aldehyde group, a ketone group, a carboxylic acid
group, and an alkoxy group. As noted above, when the reactants are
urea and glyoxal, the reaction product may be
4,5-dihydroxyimidazolidin-2-one as shown in Formula (VIII).
[0028] Additional examples of reaction products of a urea compound
with an aldehyde and/or ketone containing compound may include the
reaction products of the above-described .alpha.,.beta.-bicarbonyl
compounds and .alpha.,.gamma.-bicarbonyl compounds as represented
by Formulas (XII)-(XVII) below:
##STR00013##
[0029] The reaction product of the urea compound and the aldehyde
and/or ketone containing compound may act as a crosslinking agent
for the reducing sugar. During a curing stage the crosslinking
agent can bond to two or more reducing sugars (either polymerized
or unpolymerized) to form a crosslinked, polymeric cured
binder.
[0030] The reducing sugar may be any sugar having an aldehyde
group, or ketone group that is capable of isomerizing to produce an
aldehyde group. Exemplary reducing sugars include monosaccharaides
such as glucoses (e.g., dextrose), fructose, glyceraldehyde, and
galactose. They also include polysaccharaides such as lactose,
maltose, xylose, and amylose, among others. The binder compositions
may include a single reducing sugar or a combination of two or more
reducing sugars as the reducing sugars in the composition.
[0031] The molar ratio of the (1) crosslinking reaction product of
the urea compound and the and/or ketone containing compound to (2)
the reducing sugar generally ranges from 1:2 to 1:50. Exemplary
ratios of crosslinking agent to reducing sugar include a range from
1:4 to 1:10. FIG. 1 shows a graph of dogbone composite tests of
tensile strength for binder compositions using a reaction product
of urea [CO(NH.sub.2).sub.2] and glyoxal [OCHCHO] as the
crosslinking agent and dextrose [C.sub.6H.sub.12O.sub.6] as the
reducing sugar. The graph shows the tensile strength of the
composites peaking at 4 to 5 moles of dextrose normalized for 1
mole of the crosslinking agent. This translates into a peak tensile
strength at (crosslinking agent):(reducing sugar) mole ratios
between 1:4 and 1:5. The tensile strength shows no significant
increases for higher relative moles of the dextrose relative to the
urea-glyoxal crosslinking agent. While not wishing to be bound by a
particular theory, it is believed that the molar ratio between 1:4
and 1:10 facilitates the highest crosslinking density in the cured
binder.
[0032] In addition to the reducing sugars, the present binder
compositions may also include non-reducing sugars and celluloses,
such as starches, modified starches, celluloses, modified
celluloses, and dextrins (e.g., cyclodextrins and maltodextrins),
among others. Embodiments also include binder compositions with any
non-reducing sugars, as well as those that exclude one or more
types of the above-described non-reducing sugars. For example, the
binder composition may lack starch, modified starch, cellulose,
modified cellulose, or dextrin (e.g., maltodextrin).
[0033] The binder composition may further include one or more
additional components such as adhesion prompters, oxygen
scavengers, solvents, emulsifiers, pigments, organic and/or
inorganic fillers, flame retardants, anti-migration aids,
coalescent aids, wetting agents, biocides, plasticizers,
organosilanes, anti-foaming agents, colorants, waxes, suspending
agents, anti-oxidants, and secondary crosslinkers, among other
components. In some instances, some or all of the additional
components are pre-mixed with the binder composition before it is
applied to fibers and cured. In additional instances, some or all
of the additional components may be introduced to the curable,
curing, and/or cured fiber-containing composite during or after the
initial binder composition is applied to the fibers.
[0034] The binder compositions may also include one or more
catalysts to increase the rate of the crosslinking reactions
between the reducing sugars and crosslinking agents when the
composition is exposed to curing conditions. Exemplary catalysts
may include alkaline catalysts and acidic catalysts. The acidic
catalysts may include Lewis acids (including latent acids and
metallic salts), as well as protic acids, among other types of acid
catalysts. Lewis acid catalysts may a salt of a deprotonized anion
such as a sulfate, sulfite, nitrate, nitrite, phosphate, halide, or
oxyhalide anion in combination with one or more metallic cations
such as aluminum, zinc, iron, copper, magnesium, tin, zirconium,
and titanium. Exemplary Lewis acid catalysts include aluminum
sulfate, ferric sulfate, aluminum chloride, ferric chloride,
aluminum phosphate, ferric phosphate, and sodium hypophosphite
(SHP), among others. Exemplary latent acids include acid salts such
as ammonium sulfate, ammonium hydrogen sulfate, mono and dibasic
ammonium phosphate, ammonium chloride, and ammonium nitrate, among
other latent acid catalysts. Exemplary metallic salts may include
organo-titanates and organo-zirconates (such as those commercially
manufactured under the tradename Tyzor.RTM. by DuPont), organo-tin,
and organo-aluminum salts, among other types of metallic salts.
Exemplary protic acids include sulfuric acid, phosphoric acid,
hydrochloric acid, nitric acid, sulfonic acid compounds (i.e.,
R--S(.dbd.O).sub.2--OH) such as p-toluenesulfonic acid and
methanesulfonic acid, and carboxylic acids, among other protic
acids. Catalyst compositions may also include combinations of two
or more catalysts, for example the combination of ammonium sulfate
and diammonium phosphate.
[0035] Exemplary catalysts may further include sulfamate-containing
compounds, sulfonate-containing compounds, phosphonate-containing
compounds, and phosphamate-containing compounds. For example,
ammonium sulfamate ([NH4.sup.+[SO.sub.3NH.sub.2.sup.-]) may be a
catalyst used in the present binder compositions.
[0036] Exemplary concentrations of the catalyst (or combination of
catalysts) in the binder composition may have a range from about 1
wt. % to about 20 wt. % of the composition. For example, the
catalyst concentration may range from about 1%, 2%, 3%, 4%, 5%, 6%,
7%, etc., on the low end, and 10%, 11%, 12%, 13%, 14%, 15%, 16%,
17%, 18%, 19%, or 20 wt. % on the high end. Exemplary catalyst
concentrations may include about 5 wt. %, about 7.5 wt. %, about 8
wt. %, about 9 wt. %, and about 10 wt. %, among other
concentrations.
[0037] The pH of the present binder compositions may vary depending
upon the types and relative concentrations of the components used.
Typically the pH of the present binder compositions are slightly
acidic to alkaline with a pH range of about 6 to 8 (e.g., 6.5 to
7.5). The binder compositions have a pH that creates relatively
little or no acid-based corrosion of metal fabrication
equipment.
[0038] The binder compositions may be used to make fiber-containing
composites that include woven or non-woven fibers bound together by
a cured matrix of the binder. The fibers in the composite may
include one or more types of fibers chosen from glass fibers,
carbon fibers, mineral fibers, and organic polymer fibers, among
other kinds for fibers. At the conclusion of the curing stage, the
cured binder may be present as a secure coating on the fiber mat at
a concentration of approximately 0.5 to 50 percent by weight of the
composition, for example the cured binder may be present at
concentration of approximately 1 to 10 percent by weight of the
composition.
[0039] The fiber-containing composites may take a variety of forms,
for example construction materials including piping insulation,
duct boards (e.g., air duct boards), and building insulation,
reinforcement scrim, and roofing membranes, among other
construction materials. Additional examples may include loose-fill
blown insulation, duct liner, duct wrap, flexible duct media, pipe
insulation, tank insulation, rigid plenum liner, textile duct liner
insulation, equipment liner, oven insulation, elevated temperature
board, elevated temperature wrap, elevated temperature panel,
insulation batts and rolls, heavy density batt insulation, light
density batt insulation, exterior foundation insulation board, and
marine hull insulation, among other materials. The composites can
also find use in printed circuit boards, battery separators, and
filter stock, among other applications.
[0040] FIG. 2A-C illustrate some of these exemplary composite
materials. FIG. 2A is a simplified schematic of an exemplary
fiber-containing batt material 202 that may be used for building
insulation. The material 202 may include a batt 203 of non-woven
fibers held together by the binder. The fibers may be glass fibers
used to make fiberglass insulation (e.g, low-density or
high-density fiberglass insulation), or a blend of two or more
types of fibers, such as a blend of glass fibers and organic
polymer fibers, among other types of fibers. In some examples, a
facer 204 may be attached to one or more surfaces of the batt
203.
[0041] FIG. 2B is a simplified schematic of an exemplary
fiber-containing composite board 206 that may be used as an
insulation board, duct board, elevated temperature board, etc. The
fibers in board 206 may include glass fibers, organic polymer
fibers, carbon fibers, mineral fibers, metal fibers, among other
types of fibers, and blends of two or more types of fibers.
[0042] FIG. 2C is a simplified schematic of an exemplary
fiber-containing flexible insulation material 208 that may be used
as a wrap and/or liner for ducts, pipes, tanks, equipment, etc. The
fiber-containing flexible insulation material 208 may include a
facer 210 attached to one or more surfaces of the fiber material
212. Exemplary materials for the facer 210 may include
fire-resistant foil-scrim-kraft facing.
[0043] Specific examples of fiber-containing composites that use
the present binder compositions include low-density fiberglass
insulation (e.g., less than about 0.5 lbs/ft.sup.3) and
high-density fiberglass insulation.
[0044] The present binder compositions may be used in methods of
binding fibers to make the fiber-containing composites. The
fiber-containing composites may include fibers of one or more
types, such as glass fibers, carbon fibers, and organic polymer
fibers, among other types of fibers. The binder compositions used
to make the composites may include a reducing sugar and a reaction
product of a urea compound and an aldehyde-containing compound as
described above. The methods may include the step of applying the
binder composition to a mat of woven or non-woven fibers to make a
curable binder-fiber amalgam. The curable amalgam is then cured to
form the fiber-containing composite of fibers bound together by the
cured binder.
[0045] The step of applying the binder composition to the fibers
may be done by a variety of techniques including spraying,
spin-curtain coating, curtain coating, and dipping-roll coating.
The composition can be applied to freshly-formed fibers, or to
fibers that have been cooled and processed (e.g., cut, coated,
sized, etc.). The binder may be provided to the applicator as a
premixed composition or may be supplied to the applicator in
separate solutions for the crosslinking agent and the reducing
sugar component. In some instances where the binder composition
includes a solvent, a portion or all of the solvent may be removed
from the composition before or after its application on the
fibers.
[0046] The step of curing the binder composition may include
exposing the composition applied to the fibers to an environment
conducive to curing. For example, the curable amalgam of fibers and
binder composition may be heated to a binder curing temperature.
Exemplary binder curing temperatures may include a temperature
range from 100.degree. C. to 250.degree. C. The curing amalgam may
be heated to the curing temperature for a period of 1 minute to 100
minutes (e.g., 20 minutes).
[0047] The curing step may produce the finished fiber-containing
composite, such as fiberglass insulation. In some exemplary
methods, additional agents like an anti-dusting agent may be
applied during or following the curing step.
[0048] FIG. 3 shows a simplified schematic of an exemplary
fabrication system 300 for making the fiber-containing composites
described above. The system 300 includes fiber supply unit 302 that
supplies the fibers for the composite. The fiber supply unit 302
may be filled with pre-made fibers, or may include equipment for
making the fibers from starting materials such as molten glass or
organic polymers. The fiber supply unit 302 deposits the fibers 304
onto a porous conveyor belt 306 that transports the fibers under
the binder supply unit 308.
[0049] The binder supply unit 308 contains a liquid uncured binder
composition 310, that is deposited onto the fibers 304. In the
embodiment shown, the binder composition 310 is spray coated onto
the fibers 304 with spray nozzles 312, however, other application
techniques (e.g., curtain coating, dip coating, etc.) may be used
in addition to (or in lieu of) the spray coating technique
illustrated by nozzles 312.
[0050] The binder composition 310 applied on fibers 304 forms a
fiber and binder amalgam on the top surface of the conveyor belt
306. The belt 306 may be perforated and/or porous to allow excess
binder composition 310 to pass through the belt 306 to a collection
unit (not shown) below. The collection unit may include filters and
circulation pumps to recycle at least a portion of the excess
binder back to the binder supply unit 308.
[0051] The conveyor belt 306 transports the amalgam to an oven 314
where it is heated to a curing temperature and the binder
composition starts to cure. The temperature of the oven 314 and the
speed of the conveyor belt 306 can be adjusted to control the
curing time and temperature of the amalgam. In some instances,
process conditions may set to completely cure the amalgam into the
fiber-containing composite. In additional instances, process
conditions may be set to partially cure the amalgam into a B-staged
composite.
[0052] The amalgam may also be compressed prior to or during the
curing stage. System 300 shows an amalgam being compressed by
passing under a plate 316 that tapers downward to decrease the
vertical space available to the curing amalgam. The amalgam emerges
from under the plate 316 in a compressed state and has less
thickness than when it first made contact with the plate. The taper
angle formed between the plate 316 and conveyor belt 306 can be
adjusted to adjust the level of compression placed on the amalgam.
The partially or fully cured composite that emerges from under
plate 316 can be used for a variety of applications, including
construction materials such as pipe, duct, and/or wall insulation,
among other applications.
EXAMPLES
Example 1A
Tensile Strength Testing of Dextrose Binder Composites
[0053] Comparative tensile strength tests were conducted on
composites made with an exemplary dextrose/urea-glyoxal binder
composition and composites made with a standard commercial
polyacrylic binder composition. The dextrose/urea-glyoxal
composition was prepared by mixing 60 g of urea, 145 g of a 40 wt %
solution of glyoxal, at a temperature of 90.degree. C. for about
120 minutes. The urea and glyoxal react to form crosslinking agents
for the binder composition, including cyclic urea-glyoxal compounds
(e.g., 4,5-dihydoxyimidazolidin-2-one). Next, 918 g of water and
989 g of dextrose monohydrate (900 g active) were added to the
reacted urea-glyoxal solution to form the uncured binder
composition for making the dogbone composite. To this solution was
added 76.4 g ammonium sulfate as a catalyst. The uncured
polyacrylic binder composition was made by mixing a commercial
polyacrylic acid (QRXP-1765 acrylic resin from Dow Chemical) with
triethanol amine that acted as a crosslinking agent.
[0054] Each of the binder compositions was formulated into 25 g
samples having a 50 wt. % solids level and mixed with 1000 g of
glass beads to make uncured composites. Roughly 1 ounce samples of
the uncured composites were then spread into dogbone molds and
pressed in the molds at a pressure of about 10,000 lbs. The dogbone
samples were then released from the molds and heated at about
400.degree. F. for about 20 minutes to form cured dogbone
composites. The cured dogbone composites were roughly 25 mm wide
and 6 mm thick.
[0055] The cured dogbone composites were tested for tensile
strength in both an unaged condition and after being aged in a high
humidity atmosphere. The unaged composites were taken directly from
the curing oven and placed in an Instron tensile strength testing
instrument (Harry W. Dietert Co.--Tensile Core Grip Assembly Part
No. 610-7CA) as shown in FIG. 4. The aged composites were taken
from the curing oven and placed for 24 hours in a humidifying oven
set at approximately 95% humidity and 120.degree. F. After the aged
samples were cooled for approximately 8 hours, they were placed in
the Instron instrument to test their tensile strength.
[0056] FIG. 5 is a graph showing the dogbone tensile strength test
results for the dextrose/urea-glyoxal binder under unaged and
humid-aged conditions, as well the strength test results for the
comparative composite made from the commercial polyacrylic acid
binder. The results demonstrate that the unaged
dextrose/urea-glyoxal binder and an almost identical tensile
strength as the unaged commercial polyacrylic binder at 2.9 MPa.
When both samples were aged at 120.degree. F. and 95% humidity for
24 hours, the aged dextrose/urea-glyoxal binder showed
significantly higher tensile strength (2.15 MPa) compared with the
aged polyacrylic binder (1.6 MPa).
Example 1B
Tensile Strength Testing of Fructose/Dextrose Binder Composites
[0057] Additional tensile strength tests were conducted on
composites made with exemplary binder compositions that included
combinations of fructose and dextrose reacted with a urea-glyoxal
crosslinking agent. A first fructose+dextrose/urea-glyoxal binder
composition was prepared by mixing 60 g of urea, 145 g of a 40 wt %
solution of glyoxal, at a temperature of 90.degree. C. for about
120 minutes. The urea and glyoxal react to form crosslinking agents
for the binder composition, including cyclic urea-glyoxal compounds
(e.g., 4,5-dihydoxyimidazolidin-2-one). Next, 918 g of water and
989 g of 42 wt. % fructose and 55 wt. % dextrose monohydrate were
added to the reacted urea-glyoxal solution to form the uncured
binder composition for making the dogbone composite. To this
solution was added 76.4 g ammonium sulfate as a catalyst. A second
fructose+dextrose/urea-glyoxal binder composition was prepared
using the same components and preparation method, except the
fructose:dextrose ratio was changed to 55 wt. % fructose and 42 wt.
% dextrose. Dogbone composites were prepared from both the first
and second fructose+dextrose/urea-glyoxal binder compositions in
the same method as described in Example 1A above. The dogbone
tensile strength test results demonstrated similar tensile
strengths for the fructose+dextrose/urea-glyoxal binder
compositions as the dextrose-only compositions.
Example 2
Preparation of an Exemplary Glass-Fiber Composites
[0058] A glass-fiber composite was made from a
dextrose/urea-glyoxal binder composition and a nonwoven glass fiber
mat. Preparation of the binder composition started by mixing 60 kg
or urea into a 145 kg aqueous glyoxal solution (40 wt. % glyoxal
(58 kg on dry basis)) at room temperature until the urea dissolved.
The urea-glyoxal solution temperature was then increased to
80.degree. C. and kept at 80-85.degree. C. for 2 hours while
stirring the solution at 500 rpm to facilitate the reaction of the
urea and glyoxal. At the end of the reaction period, a 57 wt. %
solution of the urea-glyoxal crosslinking agent was formed.
[0059] 918 kg or water and 989 kg of dextrose monohydrate (900 kg
active) were added to the crosslinking solution and the combined
mixture was stirred until the dextrose dissolved. The mole ratio of
urea:glyoxal:dextrose in the solution was 1:1:5. 76.4 kg of
ammounium sulfate was added to the solution as a catalyst, and
stirred until the catalyst dissolved to make the binder
composition.
[0060] Manufacture and Testing of R19 Fiberglass Insulation
Batts
[0061] The binder composition was spray coated onto a nonwoven
glass-fiber mat made from blown filaments of sodium borosilicate
glass having diameters ranging from about 1 to 10 .mu.m and lengths
ranging from of about 5 to 100 mm. The amalgam of the fibers and
binder composition was then conveyed through a curing oven operated
at a temperature of 150.degree. C. to 350.degree. C. to heat the
amalgam to a curing temperature for about 30 seconds to 3 minutes.
The bat of glass fibers held together by the cured binder emerged
from the oven with an approximate thickness of about 3 to 4 cm and
a nominal weight of about 440 g/m.sup.2 and density of about 11.2
kg/m.sup.3.
[0062] The cured bat was used to make R-19 building insulation. The
droop (rigidity) and recovery of the batts were evaluated under
unaged conditions, as well as after aging for 7 and 14 days at
120.degree. F. and 95% humidity. The performance of the batts made
with the dextrose-urea-glyoxal binder composition was compared to
bats made with conventional binder compositions. The comparative
tests found the unaged batts made with the dextrose-urea-glyoxal
binder composition had 10% improved rigidity (i.e., lower sag)
compared with comparable batts made with a conventional binder
composition (acrylic), and the aged batts showed an even larger 20%
improvement in rigidity (lower sag). This improvement in the
rigidity of the batts made with the dextrose-urea-glyoxal binder
composition did not result in any diminishment of their recovery
performance compared to the conventional batts. In addition, the
emissions of volatile organic compounds (VOCs) from batts made with
the urea/glyoxal/dextrose binder compositions were significantly
lower than batts made with the conventional acrylic binder
compositions. No release of formaldehyde was detected from the
urea/glyoxal/dextrose batts. Table 1 below summarizes the droop,
recovery, and VOC emissions results for the various sample batts
tested:
TABLE-US-00001 TABLE 1 Droop and Recovery Results for R19
Insulation Batts Droop VOC (Rigidity) - Recovery - Emissions -
Sample [Inches] [Inches] [lb/hour] Urea/glyoxal/dextrose 2.1 6.7
0.8 binder composition (unaged) Urea/glyoxal/dextrose 3.4 6.0 N/A
binder composition (Aged 7 days) Urea/glyoxal/dextrose 3.5 6.0 N/A
binder composition (Aged 14 days) PF Binder (unaged) 2.5 6.5 0.9 PF
Binder (Aged 7 days) 4.2 6.1 N/A PF Binder (Aged 14 days) 4.5 6.0
N/A
[0063] Manufacture and Testing of Duct Board
[0064] The present dextrose-urea-glyoxal binder compositions are
also used to make duct board. Two compositions were independently
prepared using 145 kg of 40wt. % aqueous glyoxal mixed with 60 kg
urea and 989 kg dextrose monohydrate. 76.4 kg of ammonium sulfate
was added to one of the compositions, while 50 kg of ammonium
sulfate and 50kg of diammonium phosphate was added to the other.
Each of the binder compositions was used to make 1.9 cm thick duct
board having a binder content of 18 wt % and density of 700
kg/m.sup.3 using standard process conditions (e.g., cure
temperature of 500-550.degree. F.).
[0065] The structural characteristics and volatile organic compound
(VOC) emissions of the duct boards were tested and compared to duct
board made with a conventional phenol-formaldehyde (PF) binder
composition. The results showed that the droop (rigidity) and El
modulus of the duct boards made with the urea/glyoxal/dextrose
binder compositions improved by about 20% compared to the duct
boards made with the conventional PF binder composition. The
present duct boards also had significantly reduced VOC emissions
compared to the PF board. The improvements in the duct boards'
structural characteristics were similar for the
urea/glyoxal/dextrose binder compositions that included ammonium
sulfate [(NH.sub.4).sub.2SO.sub.4] alone versus the combination of
ammonium sulfate and diammonium phosphate [(NH.sub.4).sub.2SO.sub.4
and (NH.sub.4).sub.2HPO.sub.4]. Table 2 below summarizes the droop,
EI modulus, and VOC emisisons results for the various duct boards
tested:
TABLE-US-00002 TABLE 2 Droop and EI Modulus Results for Duct Boards
Droop (Rigidity) - EI Modulus - Sample [Inches] [N m.sup.2?]
Urea/glyoxal/dextrose binder 2.5 183 composition with
(NH.sub.4).sub.2SO.sub.4 alone Urea/glyoxal/dextrose binder 1.3 153
composition with (NH.sub.4).sub.2SO.sub.4 and
(NH.sub.4).sub.2HPO.sub.4 Conventional Phenol- 2.5 145 Formaldehyde
binder Composition
Additional Characteristics of the Present Insulation Batts and Duct
Boards
[0066] Fiberglass insulation batts and duct boards made with the
present urea/glyoxal/dextrose binder compositions were measured on
a number of characteristics described in Table 3 below. For all the
characteristics, the batts and boards met or exceeded current
standards requirements for residential and commercial building
materials set by the American Society for Testing and Materials
(ASTM) and Underwriters Laboratory (UL).
TABLE-US-00003 TABLE 3 Characteristics of R19 Insulation Batt and
Duct Boards Characteristic R19 Insulation Batt Duct Board Density
0.25-0.75 lbs/ft.sup.3 2.0-6.0 lbs/ft.sup.3 Loss on 3 wt. %-6 wt. %
15 wt. %-22 wt. % Ignition (LOI) Tensile 0.35-1.0 psi Strength
Thickness 5 inches-7 inches 0.9 inches-1.1 inches Recovery Dust
Testing 10-50 g/10,000 ft.sup.2 0.03-0.3 g/lb Water >0.5 wt %
>5 wt. % Absorption Flexural <400 EI Rigidity (E I)
Stiffness- .ltoreq.5 inches for 36 inch span Rigidity Hot Surface
Meets C411 Requirements Performance Corrosivity on Mass loss
corrosion rate Mass loss corrosion rate Steel <5 ppm chloride
reference <5 ppm chloride reference solution (ASTM C1617)
solution (ASTM C1617) Smoke Flame spread of <25, and Flame
spread of <25, and Development smoke developed <50 using
smoke developed <50 using on ASTM E84; ASTM E84 Ignition
Classified as Non- Combustible based on ASTM E136.
Example 3
Varying the Mole Ratio of Urea and Glyoxal in Binder
Composition
[0067] In this example, the properties of binder compositions were
compared that used urea/glyoxal reaction products with different
starting mole ratios of urea and glyoxal. Three samples were
prepared where the mole ratio of urea-to-glyoxal was 2:1, 1:1, and
1:2. Each of the urea/glyoxal reaction products were made by
combining the urea and glyoxal reactants at the respective mole
ratios into a 50 wt % aqueous solution
Formation of Urea:Glyoxal 1:2/Dextrose Binder:
[0068] To 290 g of a 40% solution of glyoxal (116 g active) in a
three neck round bottom flask equipped with stirrer, condenser and
temperature control added 60 g urea (1 mole) at ambient
temperature. After all urea dissolved, the temperature was
increased to 90.degree. C. and kept for 60 min until all reactants
were consumed and
(2R,3S,6R)-2,3,5,6-tetrahydroxy-1,4-diazabicyclo[2.2.1]heptan-7-one
product was formed as determined by HPLC. This solution was added
to a 50% solution of six moles of dextrose (1080 g) in water at
60.degree. C. After the two solutions mixed, enough water was added
to bring the final concentration to 50%.
Formation of Urea:Glyoxal 2:1 (Glycoluril)/Dextrose Binder:
[0069] To 145 g of a 40% solution of glyoxal (58 g active) in a
three neck round bottom flask equipped with stirrer, condenser and
temperature control added 120 g urea (2 moles) at ambient
temperature. After all urea dissolved, the temperature was
increased to 90.degree. C. and kept for 120 min until all reactants
were consumed and glycoluril product was formed as determined by
HPLC. This solution was added to a 50% solution of six moles of
dextrose (1080 g) in water at 60.degree. C. After the two solutions
mixed, enough water was added to bring the final concentration to
50%.
[0070] As noted above, the predominant reaction product of the urea
and glyoxal depend on the mole ratio of the two reactants. Table 4
lists the predominant reaction product for each of the three
samples:
TABLE-US-00004 TABLE 4 Predominant Urea/Glyoxal Reaction Products
for Different U:G Mole Ratios Urea:Gloyxal Mole Ratio Predominant
Reaction Product 2:1 ##STR00014## 1:1 ##STR00015## 1:2
##STR00016##
[0071] One mole of each urea-glyoxal reaction product was added to
six moles of an aqueous dextrose solution to make three 50 wt. %
solutions. An ammonium sulfate/ammonium phosphate catalyst was then
added to each of the solutions to make three sample binder
compositions. The catalyst was a 1:1 mixture of ammonium sulfate:
diammonium phosphate dissolved in water to make a 40% active
solution. Catalyst was added at 10% active ingredient based on
solid resin.
[0072] Each of the three sample binder compositions was formulated
into 25 g samples having a 50 wt. % solids level and mixed with
1000 g of glass beads to make uncured composites. Roughly 1 ounce
samples of the uncured composites were then spread into dogbone
molds and pressed in the molds at a pressure of about 10,000 lbs.
The dogbone samples were then released from the molds and heated at
about 400.degree. F. for about 20 minutes to form cured dogbone
composites. The cured dogbone composites were roughly 25 mm wide
and 6 mm thick.
[0073] The cured dogbone composites were tested for tensile
strength in both an unaged condition and after being aged in a high
humidity atmosphere in the same manner described in Example 1A
above. FIG. 6 is a graph showing the dogbone tensile strength test
results for the dextrose/urea-glyoxal binder compositions under
unaged and humid-aged conditions. The results show that binder
compositions using urea-to-glyoxal mole ratios of 1:1 and 2:1 have
similar unaged tensile strength results at about 3.2 MPa, and
similar aged tensile strength results at 2.9 MPa. The binder
composition with the 1:2 mole ratio had about 10% lower unaged
tensile strength at 2.9 MPa, and a similar reduction for aged
tensile strength at 2.5 MPa.
[0074] It was further observed that the binder composition with the
1:2 mole ratio of urea-to-glyoxal was the softest of the three
samples, and did not crack or break when used as a 15 wt. % binder
in a glass mat reinforced composition sheet that was bent around a
5 mm diameter pipe. Thus, exemplary binder compositions that use
the 1:2 mole ratio of urea-to-glyoxal may be particularly well
suited for pipe insulation and other articles that require
significant wrapping and/or bending of the insulation material.
Example 4
Exemplary Binder Compositions Using Crosslinking Agents Other Than
Urea-Glyoxal
[0075] Three binder compositions were made that included the
reaction products of urea and a dial or diol, which functioned as a
crosslinking agent in the compositions. The urea was provided in
aqueous solutions prepared by dissolving 1 mole (60 g) of urea to a
50% solids solution in room temperature water. The aqueous urea
solutions were prepared in a three-neck flask equipped with a
stirrer and a condenser. One of the urea solutions was combined in
the flask with 1 mole of 1,3 propane dial (72 g), while a second
urea solution was combined in the flask with 1 mole of 2,4 pendate
dione (99 g), and a third urea solution was combined in the flask
with 2,3 butane dione (86 g). Each combination of urea and dial or
diol was refluxed for 120 minutes to form the reaction product.
[0076] One mole of each of the three crosslinking agent solutions
was added to 6 moles (1080 g) of a 50% solids aqueous dextrose
solution (i.e., 1080 g of dextrose dissolved in 1080 g or water).
After addition of crosslinking agent solutions to each of the
dextrose solutions, the temperature of the combined solutions was
increased to 90.degree. C. for 15 minutes followed by a rapid
cooling to ambient temperature. Dogbone composite were prepared as
explained previously and the results are shown in FIG. 7.
[0077] In another set of experiments, one mole of urea (60 g) was
dissolved in 200 g of methanol. To such solution one mole of the
following was added: dimethyl malonate (132 g), dimethyl oxalate
(118 g) and methyl acetoacetate (116 g). To these solutions added
0.54 g sodium methoxide (0.01 mole) and the solutions were brought
to a reflux for 120 minutes. The methoxide was neutralized by
addition of acetic acid. After evaporation of methanol in a
rotavap, the white powder crosslinking agents were added to a
solution of six moles of dextrose (1080 g) in enough water at
60.degree. C. to make a final 50% solid solutions. The solutions
were briefly heated to 90.degree. C. for 15 minutes and cooled to
ambient temperature rapidly. Dogbone composite data is shown for
these binders in FIG. 8.
[0078] Having described several embodiments, it will be recognized
by those of skill in the art that various modifications,
alternative constructions, and equivalents may be used without
departing from the spirit of the invention. Additionally, a number
of well-known processes and elements have not been described in
order to avoid unnecessarily obscuring the present invention.
Accordingly, the above description should not be taken as limiting
the scope of the invention.
[0079] Where a range of values is provided, it is understood that
each intervening value, to the tenth of the unit of the lower limit
unless the context clearly dictates otherwise, between the upper
and lower limits of that range is also specifically disclosed. Each
smaller range between any stated value or intervening value in a
stated range and any other stated or intervening value in that
stated range is encompassed. The upper and lower limits of these
smaller ranges may independently be included or excluded in the
range, and each range where either, neither or both limits are
included in the smaller ranges is also encompassed within the
invention, subject to any specifically excluded limit in the stated
range. Where the stated range includes one or both of the limits,
ranges excluding either or both of those included limits are also
included.
[0080] As used herein and in the appended claims, the singular
forms "a", "an", and "the" include plural referents unless the
context clearly dictates otherwise. Thus, for example, reference to
"a process" includes a plurality of such processes and reference to
"the fiber" includes reference to one or more fibers and
equivalents thereof known to those skilled in the art, and so
forth.
[0081] Also, the words "comprise," "comprising," "include,"
"including," and "includes" when used in this specification and in
the following claims are intended to specify the presence of stated
features, integers, components, or steps, but they do not preclude
the presence or addition of one or more other features, integers,
components, steps, acts, or groups.
* * * * *