U.S. patent application number 11/053831 was filed with the patent office on 2005-09-29 for extended curable compositions for use as binders.
Invention is credited to Adamo, Joseph Robert, Gappert, Griffin Melaney, Weinstein, Barry, Zwolak, Thomas Tod.
Application Number | 20050214534 11/053831 |
Document ID | / |
Family ID | 34990266 |
Filed Date | 2005-09-29 |
United States Patent
Application |
20050214534 |
Kind Code |
A1 |
Adamo, Joseph Robert ; et
al. |
September 29, 2005 |
Extended curable compositions for use as binders
Abstract
The present invention provides low-cost formaldehyde-free
curable aqueous compositions comprising 100 weight parts of one or
more than one binder chosen from (i) mixtures of one or more than
one polycarboxylic acid or polymeric polyacid and one or more than
one polyol compound comprising at least two hydroxyl or epoxy
groups, (ii) copolymers or copolymeric polyacids bearing carboxylic
acid groups or anhydride groups and hydroxyl groups, and (iii)
mixtures thereof, and 10 to 40 weight parts of one or more than one
extender having an average particle size ranging from 0.5 .mu.m or
more and as high as 45 .mu.m or less, preferably chosen from
microcrystalline silica, diatomaceous silica, kaolin, bentonite,
and anhydrous aluminosilicate clay delaminated. In the inventive
binder compositions, the ratio of the wet over dry tensile strength
of said composition is about 0.5 or greater. The present invention
further provides products coated or impregnated with the binder,
such as heat-resistant fiberglass nonwovens used for insulation.
The aqueous binder may further comprise one or more
phosphorous-containing accelerator.
Inventors: |
Adamo, Joseph Robert;
(Souderton, PA) ; Weinstein, Barry; (Dresher,
PA) ; Gappert, Griffin Melaney; (Philadelphia,
PA) ; Zwolak, Thomas Tod; (Bensalem, PA) |
Correspondence
Address: |
ROHM AND HAAS COMPANY
PATENT DEPARTMENT
100 INDEPENDENCE MALL WEST
PHILADELPHIA
PA
19106-2399
US
|
Family ID: |
34990266 |
Appl. No.: |
11/053831 |
Filed: |
February 9, 2005 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60557348 |
Mar 29, 2004 |
|
|
|
Current U.S.
Class: |
428/375 |
Current CPC
Class: |
H05K 2201/0209 20130101;
H05K 1/0373 20130101; Y10T 428/2933 20150115 |
Class at
Publication: |
428/375 |
International
Class: |
D02G 003/00 |
Claims
I claim:
1. A curable aqueous composition comprising: 100 weight parts of
one or more than one binder chosen from: (i) mixtures of one or
more than one polycarboxylic acid or polymeric polyacid, each
comprising at least two carboxylic acid groups, anhydride groups or
salts thereof, and one or more than one polyol compound having a
molecular weight of 1000 or less and comprising at least two
hydroxyl groups or epoxy groups, (ii) one or more copolymer or
copolymeric polyacid including, as copolymerized units, one or more
monomer bearing carboxylic acid groups or anhydride groups, and one
or more hydroxyl group-bearing monomer, and (iii) mixtures of (i)
and (ii), wherein, the said carboxylic acid groups, anhydride
groups or salts thereof are neutralized to the extent of 35% or
less with a fixed base, and, further wherein, the ratio of the
number of equivalents of the said carboxylic acid groups, anhydride
groups or salts thereof in any of the said one or more than one
binder to the number of equivalents of the said hydroxyl groups in
the same said one or more than one binder is from 1/0.01 to 1/3,
and 10 to 40 weight parts of one or more than one extender having
an average particle size ranging from 0.5 .mu.m or more and as high
as 45 .mu.m or less chosen from microcrystalline silica,
diatomaceous silica, kaolin, bentonite, smectite, vermiculite,
calcined aluminum silicate, anhydrous aluminosilicate clay
delaminated wollastonite, calcium metasilicate, ground glass,
nepheline syenite, hydrotalcite, and mixtures thereof, wherein the
wet over dry tensile strength of said composition is about 0.5 or
greater.
2. A composition as claimed in claim 1, further comprising one or
more phosphorous-containing accelerator.
3. A composition as claimed in claim 1, further comprising one or
more emulsion polymer including, as copolymerized units, greater
than 30 wt. %, based on the weight of the emulsion polymer solids,
of an ethylenically unsaturated acrylic monomer including one or
more C.sub.5 or greater alkyl group.
4. A composition as claimed in claim 1, wherein the said binder
comprises binder (i) and the said polyol comprises one or more
epoxy resin.
5. A composition as claimed in claim 1, wherein the ratio of the
hot-wet tensile strength to the dry tensile strength of said
composition when cured is about 0.70 or greater.
6. A composition as claimed in claim 1, wherein the said extender
has been screened so as to pass through a screen having a grid size
ranging from more than 0.5 .mu.m to 45 .mu.m and so as not to pass
through a screen or filter having a grid size or lower resolution
limit of 0.5 .mu.m.
7. A curable aqueous composition comprising: 100 weight parts of
one or more than one binder chosen from one or more copolymer or
copolymeric polyacid including, as copolymerized units, one or more
monomer bearing carboxylic acid groups or anhydride groups, and one
or more hydroxyl group-bearing monomer, wherein, the said
carboxylic acid groups, anhydride groups or salts thereof are
neutralized to the extent of 35% or less with a fixed base, and,
further wherein, the ratio of the number of equivalents of the said
carboxylic acid groups, anhydride groups or salts thereof in the
said one or more than one binder to the number of equivalents of
the said hydroxyl groups in the same said one or more than one
binder is from 1/0.01 to 1/3, and, 10 to 40 weight parts of one or
more than one extender having an average particle size ranging from
0.5 .mu.m or more and as high as 45 .mu.m or less chosen from
microcrystalline silica, diatomaceous silica, kaolin, bentonite,
anhydrous aluminosilicate clay delaminated, wollastonite, smectite,
vermiculite, calcined aluminum silicate, wollastonite, calcium
metasilicate, alkali aluminum silicate, ground glass, nepheline
syenite, titanium dioxide, zinc oxide, mica, hydrotalcite, and
mixtures thereof, wherein the wet over dry tensile strength of said
composition is about 0.5 or greater.
8. A composition as claimed in claim 7, wherein the said extender
has been screened so as to pass through a screen having a grid size
ranging from more than 0.5 .mu.m to 45 .mu.m and so as not to pass
through a screen or filter having a grid size or lower resolution
limit of 0.5 .mu.m.
9. A composition as claimed in claim 7, wherein the said copolymer
or copolymeric polyacid further comprises, as copolymerized units,
one or more ethylenically unsaturated monomer having a solubility
of less than 2 g/100 g of water at 25.degree. C. in the amount of 3
to 25 wt. %, based on the total weight of monomers used to make the
curable aqueous binder composition, the said ethylenically
unsaturated monomer chosen from ethyl (meth)acrylate, methyl
methacrylate, butyl (meth)acrylate, styrene, mono-alkyl
(meth)acrylamide, and di-alkyl (meth)acrylamide.
10. A non-woven heat resistant fibrous substrate coated or
impregnated with the cured composition as claimed in claim 1.
Description
FIELD OF THE INVENTION
[0001] The present invention relates to reduced cost,
formaldehyde-free curable aqueous binder compositions containing
extenders and yet retain their hot wet tensile strength properties
when cured. More specifically, the present invention relates to
compositions comprising from 10 to 40 weight % of one or more
extender, based on the weight of one or more formaldehyde-free
curable aqueous binder, wherein the ratio of the hot-wet tensile
strength to the dry tensile strength of said composition, is about
0.5 or greater.
BACKGROUND OF THE INVENTION
[0002] Binders for heat-resistant non-woven materials, such as
fiberglass insulation, have mostly contained resins, such as
formaldehyde condensate resins that include urea-formaldehyde (UF)
and phenol-formaldehyde (PF). These resins are inexpensive, however
they steadily emit harmful formaldehyde gasses over their useful
life. Further, such resins tend to yellow over time and can emit a
foul odor when wet.
[0003] Recently, formaldehyde-free acrylic thermosetting binders
have been introduced. Such aqueous acrylic resins, despite being
odor-free and emitting virtually no formaldehyde have increased the
cost of manufacturing fiberglass insulation or other fibrous
products compared to costs associated with the use formaldehyde
condensates.
[0004] U.S. Pat. No. 6,146,746, to Reck et al., discloses
thermosettable aqueous binders comprising carboxylic acid
functional polymers obtained by free-radical polymerization mixed
with alkanolamines, which binders may contain auxiliaries such as
aluminum silicates, pyrogenic silica, precipitated silica,
fluorspar and heavy spar, talc, calcium carbonate and iron oxide.
The binders allegedly provide good flexural modulus under hot and
damp conditions. However, the auxiliaries mentioned can hamper the
effectiveness of the binder or reduce the strength of the cured
binder below acceptable levels. For example, pyrogenic silica, like
any nanoparticle-size additive, can absorb binder, thereby masking
its effectiveness. Calcium carbonate and iron oxide both interfere
with the condensation reaction that cures the binder, and the
carbonate also induces foaming and neutralizes the carboxylic acid
functional polymer.
[0005] Accordingly, the present inventors have unexpectedly
discovered formaldehyde-free aqueous binder compositions that are
lower in cost than the prior formaldehyde-free binders and which
provide good hot wet tensile strengths when cured and which do not
suffer from the disadvantages discussed above.
SUMMARY OF THE INVENTION
[0006] According to the present invention, formaldehyde-free
curable aqueous compositions comprise 100 weight parts of one or
more than one binder chosen from (i) mixtures of one or more than
one polycarboxylic acid or polymeric polyacid, each comprising at
least two carboxylic acid groups, anhydride groups or salts
thereof, and one or more than one polyol compound having a
molecular weight of 1000 or less and comprising at least two
hydroxyl or epoxy groups, (ii) one or more copolymer or copolymeric
polyacid including, as copolymerized units, one or more monomer
bearing carboxylic acid groups or anhydride groups and one or more
hydroxyl group-bearing monomer, and (iii) mixtures of (i) and (ii),
wherein, the said carboxylic acid groups, anhydride groups or salts
thereof are neutralized to the extent of 35% or less with a fixed
base, and, further wherein, in each of (i) and (ii), the ratio of
the number of equivalents of the said carboxylic acid groups,
anhydride groups or salts thereof to the number of equivalents of
the said hydroxyl groups is from 1/0.01 to 1/3, the binder mixed
with 10 to 40 weight parts of one or more than one extender having
an average particle size ranging from 0.5 .mu.m or more and as high
as 45 .mu.m or less chosen from microcrystalline silica, kaolin,
diatomaceous silica, calcined aluminum silicate, wollastonite,
calcium metasilicate, alkali aluminum silicate, anhydrous
aluminosilicate clay delaminated, ground glass, nepheline syenite,
hydrotalcite, mica, smectite, vermiculite, titanium dioxide, zinc
oxide, and mixtures thereof.
[0007] In the inventive binder compositions, the ratio of the wet
over dry tensile strength of said composition is about 0.5 or
greater.
[0008] According to the present invention, a product coated or
impregnated with the binder comprises heat-resistant nonwovens such
as, for example, nonwovens composed of fiberglass or other
heat-resistant fibers used for insulation. Binder coated or
impregnated articles may comprise fibrous shaped articles, such as
sheets or panels, wherein the articles may comprise heat-resistant
fibers, such as glass fiber, natural fibers, such as cellulosics,
hemp, sisal or animal fiber, or synthetic fibers, such as aramid or
PVC fiber.
[0009] The aqueous binder may further comprise one or more
phosphorous-containing accelerator. Additionally, the aqueous
binder may further comprise one or more emulsion (co)polymer, one
or more epoxy resin or other highly reactive polyol, or
combinations thereof.
DETAILED DESCRIPTION OF THE INVENTION
[0010] This invention is directed to a low cost, formaldehyde-free
curable aqueous binder compositions that comprise 10 wt. % or more,
or 15 wt. % or more, and as much as 40 wt. %, or as much as 30 wt.
%, based on binder solids, of an inorganic extender while
maintaining the hot wet tensile strength and the performance of the
cured binder, also referred to as "hot-wet retention".
Specifically, the ratio of the hot-wet tensile strength of the
extender-containing binder composition of the present invention to
the dry tensile strength of the same binder, when cured is about
0.5 or greater, preferably about 0.70 or greater, and, more
preferably, about 0.8 or greater. Further, products coated or
impregnated with the cured binder exhibit good "recovery", which is
defined as the relative thickness of a fiberglass insulation batt
after compression.
[0011] The compositions of the present invention provide
reduced-cost, formaldehyde free binders useful for coating and
impregnating heat-resistant nonwovens, such as nonwovens composed
of fiberglass, e.g. fiberglass insulation, or other fibrous
substrates, such as sheets or ceiling panels.
[0012] In measuring the ratio of the hot-wet tensile strength of
the cured extender-containing binder composition to the dry tensile
strength of the same cured binder, the uncertainty may range as
high as 0.05. Accordingly, such a measured ratio having a value of
"about 0.5" may include actual ratios of from 0.45 to 0.55.
[0013] All ranges recited are inclusive and combinable. For
example, an average particle size of 1.3 .mu.m or more, for
example, 1.5 .mu.m or more, which may be 4.5 .mu.m or less, or 4.0
.mu.m or less, will include ranges of 1.3 .mu.m or more to 4.5
.mu.m or less, 1.5 .mu.m or more to 4.5 .mu.m or less, 1.5 .mu.m or
more to 4.3 .mu.m or less, and 1.3 .mu.m or more to 4.3 .mu.m or
less.
[0014] Unless otherwise indicated, all temperature and pressure
units are standard temperature and pressure (STP).
[0015] All phrases comprising parenthesis denote either or both of
the included parenthetical matter and its absence. For example, the
phrase "(co)polymer" includes, in the alternative, polymer,
copolymer and mixtures thereof.
[0016] As used herein, the phrase "wet over dry tensile strength"
means a ratio of those two strengths when measured, as follows:
Prepare a sample of binder-impregnated glass microfiber filter
paper (20.3 cm.times.25.4 cm) by drawing it through a trough filled
with 200 g of a pre-mixed binder solution that has been further
mixed by agitation, sandwiching the soaked sample between two
cardboard sheets to absorb excess binder, and pressing between the
two cardboard sheets in a Birch Brothers Laboratory Patter set at a
speed setting of 5 and at a pressure of 10 psi (68.9476 kPa). Dry
the sample at 90.degree. C. in a Mathis Oven that is vented or
equipped with a devolatilizer for 90 seconds and, when dry, weigh
it to determine a post-dry weight for calculating add-on. Cure the
sample at 210.degree. C. for 60 seconds in a Mathis Oven that is
vented or equipped with a devolatilizer. Cut the cured coated
sheets into 1 in.times.4 in (2.54 cm.times.10.16 cm) in size for
tensile strength testing. Soak the cut cured coated sheets for 30
minutes at 85.degree. C. just prior to wet tensile strength
testing. Test tensile strength of each of the wet and dry samples
in the machine direction in a Thwing-Albert Intelect 500 tensile
tester, having a fixture gap set at 2 inches (5.08 cm) and a pull
rate set at 2 inches/minute (5.08 cm/minute). Record each tensile
strength as the peak force measured during parting or breaking each
tested strip in two. Finally, divide wet tensile strength by dry
tensile strength to calculate a ratio of the wet tensile strength
to the dry tensile strength.
[0017] As used herein, the phrase "addition polymer" refers to any
(co)polymer that comprises ethylenically unsaturated monomers as
(co)polymerized units, such as the polymeric polyacid and the
copolymer.
[0018] As used herein, the phrase "aqueous" includes water and
mixtures composed substantially of water and water-miscible
solvents.
[0019] As used herein, the phrase "average particle size", refers
to particle diameter or the largest dimension of a particle this
can be determined by laser light scattering or by a sedimentation
method using a hygrometer or other suitable means. In the
sedimentation method, the reported average particle size "x"
denotes the point on the particle size distribution curve at which
50% by weight of the measured batch of particles is finer than than
"x".
[0020] As used herein, unless otherwise indicated, the phrase
"copolymer" includes, independently, copolymers, terpolymers, block
copolymers, segmented copolymers, graft copolymers, and any mixture
or combination thereof.
[0021] As used herein, the phrase "delaminated" and "exfoliated"
clay refer to layered silicates in which the layers have been
separated from each other.
[0022] As used herein, unless otherwise indicated, the phrase "melt
viscosity" refers to the melt viscosity of a polymer or resin, as
measured in centipoises at 150.degree. C. using a Brookfield
Viscometer in accordance with the manufacturer or equipment
supplier's recommendations.
[0023] As used herein, the term "maleic" comprises either maleic
acid or maleic anhydride independently of each other, unless
otherwise indicated.
[0024] As used herein, the term "(meth)acrylate" means acrylate,
methacrylate, and mixtures thereof and the term "(meth)acrylic"
used herein means acrylic, methacrylic, and mixtures thereof.
[0025] As used herein, unless otherwise indicated, the phrase
"molecular weight" refers to the weight average molecular weight of
a polymer as measured by gel permeation chromatography.
[0026] As used herein, the phrase "wt. %" stands for weight
percent.
[0027] The extenders useful in the present invention have an
average particle size, as determined by laser light scattering, of
0.5 .mu.m or more, or 5 .mu.m or more and as high as 45 .mu.m or
less, or 35 .mu.m or less. Extenders having more than 50 wt. % of
fines less than 1 .mu.m in diameter provide an excessive surface
area and absorb in the surface of the substrate, effectively
preventing the binder from sticking to the substrate. Extenders
having an average particle size of more than 45 .mu.m interfere
with the continuous interface between binder and substrate.
Preferably, extenders are screened prior to use in a screen which
limits their particle size to an acceptable range. Suitable screens
have a grid size ranging from 0.5 .mu.m to 45 .mu.m, or from 12,700
mesh to 325 mesh, that is, they allow particles having a size of
from 1 .mu.m to 45 .mu.m to pass through them. More preferably,
suitable extenders will pass through a screen having a 45 .mu.m
grid size but would not pass through a screen having a 0.5 .mu.m
grid size or a filter having a 0.5 .mu.m lower resolution limit.
Thus, extenders may be screened by passing them through a 45 .mu.m
and onto a grid plate, screen or filter having a 0.5 .mu.m grid
size or lower resolution limit.
[0028] Suitable extenders should not react with the binder or
interfere with the curing of the binder. For this reason, the
extenders of the present invention are not iron leachable, and do
not foam or react in the presence of carboxylic acid. Accordingly,
suitable extenders do not contain iron, sulfate, phosphate or
carbonate groups. In addition, suitable extenders may be calcined
to minimize their ability to absorb binder. Such extenders may
include calcined clay and calcined silicates, such as calcined
aluminum silicates.
[0029] Suitable extenders may be chosen from microcrystalline
silica, kaolin, bentonite, calcined aluminum silicate,
wollastonite, calcium metasilicate, alkali aluminum silicate,
diatomaceous silica, ground glass, nepheline syenite, hydrotalcite,
mica, smectite, vermiculite, anhydrous aluminosilicate clay
delaminated, titanium dioxide, zinc oxide, and mixtures thereof.
Smectite includes the layered clays and phyllosilicates, such as
montmorillonite, bentonite, saponite, beidellite, montronite,
hectorite, and stevensite. Kaolin clay, smectites or
phyllosilicates may or may not be surface treated to render them
hydrophobic, such as with trialkylarylammonium compounds.
[0030] Preferred extenders may comprise microcrystalline silica,
diatomaceous silica, bentonite and kaolin clays, anhydrous
aluminosilicate delaminated, or their mixtures. Microcrystalline
silica comes in several forms, including cristobalite or
christobalite and tridymite.
[0031] Binder compositions may comprise one or more mixtures of one
or more than one polycarboxylic acid or polymeric polyacid, each
comprising at least two carboxylic acid groups, anhydride groups or
salts thereof, and one or more than one polyol compound having a
molecular weight of 1000 or less and comprising at least two
hydroxyl groups and, optionally, a phosphorous-containing
accelerator, wherein the ratio of the number of equivalents of said
carboxylic acid groups, anhydride groups, or salts thereof to the
number of equivalents of said hydroxyl groups is from 1/0.01 to
1/3, and wherein the carboxyl groups are neutralized to an extent
of less than 35% with a fixed base.
[0032] Alternatively, binders may comprise one or more rapidly
curing copolymer or copolymeric polyacid including, as
copolymerized units, one or more monomer bearing carboxylic acid
units and one or more hydroxyl group-bearing monomer, wherein the
ratio of the number of equivalents of the said carboxylic acid
groups, anhydride groups or salts thereof to the number of
equivalents of the said hydroxyl groups is from 1/0.01 to 1/3, and,
further wherein, the said carboxylic acid groups, anhydride groups
or salts thereof are neutralized to the extent of 35% or less with
a fixed base.
[0033] The formaldehyde-free curable aqueous composition is
substantially thermoplastic, or substantially uncrosslinked, when
it is applied to the substrate, although low levels of deliberate
or adventitious crosslinking may be present. On heating the binder,
the binder is dried and curing is effected, either sequentially or
concurrently. By "curing" is meant herein a structural or
morphological change which is sufficient to alter the properties of
a flexible, porous substrate to which an effective amount of
polymeric binder has been applied such as, for example, covalent
chemical reaction, ionic interaction or clustering, improved
adhesion to the substrate, phase transformation or inversion,
hydrogen bonding, and the like.
[0034] This invention is directed to a formaldehyde-free curable
aqueous composition. By "formaldehyde-free composition" herein is
meant that the composition is substantially free from formaldehyde,
and does not liberate substantial formaldehyde as a result of
drying and/or curing. To minimize the formaldehyde content of the
waterborne composition it is preferred, when preparing a
polymer-containing formaldehyde-free curable aqueous composition,
to use polymerization adjuncts such as, for example, initiators,
reducing agents, chain transfer agents, biocides, surfactants, and
the like, which are themselves free from formaldehyde, do not
generate formaldehyde during the polymerization process, and do not
generate or emit formaldehyde during the treatment of the treatment
of one or more substrates. By "substantially free from
formaldehyde" herein is meant that when low levels, e.g. less than
2.0 wt. %, preferably less than 0.1 wt. %, more preferably less
than 0.0001 wt. %, and most preferably less than 100 ppb of
formaldehyde are acceptable in the waterborne composition or when
compelling reasons exist for using adjuncts which generate or emit
formaldehyde, substantially formaldehyde-free waterborne
compositions may be used.
[0035] Suitable polycarboxylic acids should be sufficiently
nonvolatile that they will remain available for reaction with the
polyol in the composition during heating and curing operations. The
polyacid may be one or more compound having a molecular (formula)
weight less than 1000 bearing at least two carboxylic acid groups,
anhydride groups, or salts thereof such as, for example, citric
acid, butane tricarboxylic acid, and cyclobutane tetracarboxylic
acid.
[0036] Suitable polymeric polyacids may include, for example, one
or more polyesters containing at least two carboxylic acid groups,
or addition polymers or oligomers containing at least two
copolymerized carboxylic acid or carboxylic anhydride functional
monomers. The polymeric polyacid may preferably be one or more
addition polymer formed from at least one ethylenically unsaturated
monomer. The addition polymer may be in the form of a solution of
the addition polymer in an aqueous medium including, for example,
one or more alkali-soluble resin which has been solubilized in a
basic medium, may be in the form of an aqueous dispersion such as,
for example, an emulsion-polymerized dispersion, or may be or in
the form of an aqueous suspension.
[0037] The copolymer including, as copolymerized units, one or more
monomer bearing carboxylic acid units and one or more hydroxyl
group-bearing monomer (hereinafter "the copolymer"), may be the
polymerization reaction product of one or more ethylenically
unsaturated carboxylic acids and one or more hydroxyl-group
containing ethylenically unsaturated comonomer.
[0038] Each of the (co)polymeric polyacid and the copolymer contain
at least two carboxylic acid groups, anhydride groups, or salts
thereof. Units that may be copolymerized therein include
ethylenically unsaturated carboxylic acids such as, for example,
methacrylic acid, acrylic acid, crotonic acid, fumaric acid, maleic
acid, 2-methyl maleic acid, itaconic acid, citraconic acid,
mesaconic acid, 2-methyl itaconic acid, cyclohexenedicarboxylic
acid, .alpha.,.beta.-methylene glutaric acid, monoalkyl maleates,
and monoalkyl fumarates; ethylenically unsaturated anhydrides such
as, for example, maleic anhydride, itaconic anhydride, citraconic
anhydride, mesaconic anhydride, acrylic anhydride, and methacrylic
anhydride; and salts thereof. Such monomers should be used in the
copolymer or the copolymeric polyacid in amounts that provide acid
copolymerized units in the amount of from 1 to 100 wt. %, based on
the weight of the addition polymer. In the copolymer, such monomers
should be used in amounts that provide acid copolymerized units at
a level of from 1 to 99 wt. %, more preferably at a level of from
10 to 90 wt. %, based on the weight of the copolymer. The remainder
of the copolymer or copolymeric polyacid (aside from copolymerized
acid group-containing units) may comprise hydroxyl group containing
copolymerized units, and, optionally, copolymerized units of
additional ethylenically unsaturated monomers. Accordingly, the
copolymer and the copolymeric polyacid may comprise, as
copolymerized units, hydroxyl group containing ethylenically
unsaturated monomers, and, optionally, as copolymerized units,
additional ethylenically unsaturated monomers.
[0039] The at least one copolymerized hydroxyl containing monomer
in the copolymer of the present invention may comprise one or more
hydroxyl group-including monomer of Formula I,
CH2=C(R1)CH(R2)OR3 (I)
[0040] wherein R1 and R2 are independently selected from hydrogen,
methyl, and --CH2OH; and R3 is selected from hydrogen,
--CH2CH(CH3)OH, --CH2CH2OH, C(CH2OH)2--C2H5, and (C3-C12) polyol
residues; or of Formula 1
[0041] wherein R is selected from CH3, Cl, Br, and C6H5; and R1 is
selected from H, OH, CH2OH, CH(CH3)OH, glycidyl, CH(OH)CH2OH, and
(C3-C12)polyol residues; preferably at a level of from 1% to 99%,
more preferably at a level of from 10% to 90% by weight, based on
the weight of the polymer. Preferred hydroxyl group-containing
monomers are allyl alcohol and 3-allyloxy-1,2-propanediol. Monomers
of Formula I and Formula II can be prepared by a variety of
synthetic routes known to those skilled the art. For example, allyl
chloride can be reacted with various polyhydroxy compounds to give,
for example, the corresponding allyloxy derivatives of sugars,
glycerine, erythritol, trimethylolpropane (CAS# 77-99-6) and
pentaerythritol. Alternatively, allyl alcohol can be reacted with
various halomethyl derivatives, especially chloromethyl compounds,
to prepare allyloxy derivatives; for example, the reaction of allyl
alcohol with epichlorohydrin would produce
3-allyloxy-1,2-propanediol. Vinyl glycols, such as
1-butene-3,4-diol, for example, can be prepared by methods such as
those described in U.S. Pat. No. 5,336,815. Allyloxy compounds that
would hydrolyze to allyloxy compounds of Formula I under the
conditions of aqueous polymerization, for example allyl
glycidylether, are also useful as monomers to produce polymer
additives of the present invention.
[0042] The (C.sub.3-C.sub.12)-containing polyols useful to prepare
allyloxy compounds of Formula I include, for example,
(C.sub.3-C.sub.6)-polyhydroxy compounds such as erythritol,
pentaerythritol and glycerine; and sugar alcohols such as xylitol,
sorbitol and mannitol. Additional suitable
(C.sub.3-C.sub.12)-containing polyols include, for example,
polyhydroxy aldehyde and ketone sugars such as glucose, fructose,
galactose, maltose, sucrose, lactose, erythrose and threose.
Examples of suitable unsaturated non-ionizable monomers include
allyl alcohol, methallyl alcohol, allyloxyethanol,
allyloxypropanol, 3-allyloxy-1,2-propanediol, trimethylolpropane
allyl ether, allyloxy(sugars), such as allyloxy(glucose),
allyloxy(fructose) and allyloxy(mannose), erythritol monoallyl
ether, pentaerythritol monoallyl ether, and 1-butene-3,4-diol. The
prefixes "(C.sub.3-C.sub.12)-" and "(C.sub.3-C.sub.6)-," as used
herein, refer to organic compounds or structural portions of
organic compounds containing 3 to 12 carbon atoms and 3 to 6 carbon
atoms, respectively. The terms "polyol" and "polyhydroxy," as used
herein, refer to organic compounds or structural portions of
organic compounds containing two or more hydroxy groups.
[0043] Useful additional ethylenically unsaturated monomers may be
included as copolymerized units in each of the copolymeric polyacid
and the copolymer. Such monomers may include acrylic ester monomers
including methyl acrylate, ethyl acrylate, butyl acrylate,
2-ethylhexyl acrylate, decyl acrylate, methyl methacrylate, butyl
methacrylate, isodecyl methacrylate, hydroxyethyl acrylate,
hydroxyethyl methacrylate, and hydroxypropyl methacrylate;
acrylamide or substituted acrylamides; styrene or substituted
styrenes; butadiene; vinyl acetate or other vinyl esters;
acrylonitrile or methacrylonitrile; and the like.
[0044] In an embodiment of the present invention, the copolymeric
polyacid or the copolymer has improved water resistance and further
comprises as copolymerized units one or more ethylenically
unsaturated monomer having a solubility of less than 2 g/100 g of
water at 25.degree. C. in the amount of 3 or more wt. %, and as
much as 25 wt. % or less, or 20 wt. % or less, or 15 wt. % or less,
based on the total weight of monomers used to make the curable
aqueous binder composition. The ethylenically unsaturated monomer
may be chosen from ethyl (meth)acrylate, methyl methacrylate, butyl
(meth)acrylate, styrene, mono-alkyl (meth)acrylamide, and di-alkyl
(meth)acrylamide. Still further, the copolymeric polyacid or the
copolymer may comprise, as copolymerised units, one or more
polyacid homopolymer.
[0045] The preferred amount of each of the ethylenically
unsaturated monomers varies depending on the monomer used. In
general, it is preferred to use from 3 to 15 wt. %, based on the
total weight of monomers in the curable aqueous binder composition,
of ethylenically unsaturated monomer having a solubility in water
of less than 1 g/100 g water at 25.degree. C. Further, it is
preferred to use from 10 to 25 wt. %, based on the total weight of
monomers in the curable aqueous binder composition, of
ethylenically unsaturated monomers having a solubility in water of
from 1 g/100 g to 2 g/100 g water at 25.degree. C. Specifically, it
is preferred to use from 10 to 25 wt. % ethyl (meth)acrylate, from
10 to 20 wt. % methyl methacrylate, from 3 to 15 wt. % butyl
(meth)acrylate, from 3 to 10 wt. % styrene, from 3 to 8 wt. %
t-octyl acrylamide, and from 5 to 15 wt. % t-butyl acrylamide,
based on the total weight of monomers in the curable aqueous binder
composition.
[0046] The (co)polymeric polyacid and the copolymer each may have a
weight average molecular weight, as measured by gel permeation
chromatography (GPC), of from 300 to 10,000,000. Preferred is a
molecular weight of 500 or more, more preferably 1000 or more, and
the preferred molecular weight may range as high as 250,000, more
preferably it may range up to 20,000. When the (co)polymeric
polyacid is one or more alkali-soluble resin having a carboxylic
acid, anhydride, or salt thereof, in the amount of from 5 to 30 wt
%, based on the total weight of the (co)polymeric polyacid, a
molecular weight from 5,000 to 100,000 is preferred. Higher
molecular weight alkali-soluble resins can lead to curable
compositions which exhibit excessive viscosity. When the copolymer
is one or more alkali-soluble resin having a carboxylic acid,
anhydride, or salt thereof, in the amount of from 5 to 50 wt %,
based on the total weight of the copolymer, a molecular weight from
5,000 to 100,000 is preferred because higher molecular weight
alkali-soluble copolymers can lead to curable compositions which
exhibit excessive viscosity.
[0047] When the addition polymer is in the form of an aqueous
dispersion or an aqueous suspension and low levels of
precrosslinking or gel content are desired, low levels of
multi-ethylenically unsaturated monomers such as, for example,
allyl methacrylate, diallyl phthalate, 1,4-butylene glycol
dimethacrylate, 1,6-hexanedioldiacrylate, and the like, may be used
at a level of from 0.01% to 5%, by weight based on the weight of
the acrylic emulsion copolymer.
[0048] When the addition polymer is in the form of an aqueous
dispersion the diameter of the addition polymer particles may be
from 80 nanometers to 1000 nanometers, as measured using a
Brookhaven BI-90 Particle Sizer, which employs a light scattering
technique. However, polymodal particle size distributions such as
those disclosed in U.S. Pat. Nos. 4,384,056 and 4,539,361, hereby
incorporated herein by reference, may be employed.
[0049] When the addition polymer is in the form of an aqueous
dispersion the addition polymer particles may be made up of two or
more mutually incompatible copolymers. These mutually incompatible
copolymers may be present in various morphologies, for example,
core/shell particles, core/shell particles with shell phases
incompletely encapsulating the core, core/shell particles with a
multiplicity of cores, interpenetrating network particles, and the
like.
[0050] The addition polymer may be prepared by solution
polymerization, emulsion polymerization, or suspension
polymerization techniques for polymerizing
ethylenically-unsaturated monomers which are well known in the art.
When it is desired to use emulsion polymerization, anionic or
nonionic surfactants, or mixtures thereof, may be used. The
polymerization may be carried out by various means such as, for
example, with all of the monomer in the reaction kettle at the
beginning of the polymerization reaction, with a portion of the
monomer in emulsified form present in the reaction kettle at the
beginning of the polymerization reaction, and with a small particle
size emulsion polymer seed present in the reaction kettle at the
beginning of the polymerization reaction.
[0051] The polymerization reaction to prepare the addition polymer
may be initiated by various methods known in the art such as, for
example, by using the thermal decomposition of an initiator and by
using an oxidation-reduction reaction ("redox reaction") to
generate free radicals to effect the polymerization. In another
embodiment the addition polymer may be formed in the presence of
phosphorous-containing chain transfer agents such as, for example,
hypophosphorous acid and its salts, as is disclosed in U.S. Pat.
No. 5,294,686, which is hereby incorporated herein by reference, so
as to incorporate the phosphorous-containing accelerator and the
polyacid component in the same molecule. The polymer can be
prepared in solvent/water mixtures such as, for example,
i-propanol/water, tetrahydrofuran/water, and dioxane/water.
[0052] Chain transfer agents such as mercaptans, polymercaptans,
and halogen compounds may be used in the polymerization mixture to
moderate the molecular weight of the acrylic emulsion copolymer.
Generally, from 0% to 1% by weight, based on the weight of the
polymeric binder, of C.sub.4-C.sub.20 alkyl mercaptans,
mercaptopropionic acid, or esters of mercaptopropionic acid, may be
used.
[0053] The carboxylic acid groups, anhydride groups, or the salts
thereof in the polyacid component, polymeric polyacid or copolymer
of the formaldehyde-free curable aqueous composition are
neutralized with fixed base to an extent of less than 35%,
calculated on an equivalents basis. The term "neutralization", as
used herein, means contacting the polyacid component, polymeric
polyacid or copolymer with one or more fixed base before, during,
or after the preparation of the curable aqueous composition.
Neutralization should, if it is desired, be performed prior to
treating a fibrous, e.g. nonwoven, substrate. Preferably, less than
20% of the carboxylic acid groups, calculated on an equivalents
basis, are neutralized with a fixed base. More preferably, less
than 5% of the carboxylic acid groups, calculated on an equivalents
basis, are neutralized with a fixed base. When the half ester of a
dicarboxylic acid or the anhydride of a dicarboxylic acid is used,
the equivalents of acid are calculated to be equal to those of the
corresponding dicarboxylic acid.
[0054] "Fixed base", or "permanent base", as used herein, refers to
a monovalent base which is sufficiently nonvolatile that it will
remain non-volatile under the conditions of the neutralization
treatment. Such bases may include, for example, sodium hydroxide,
potassium hydroxide, sodium carbonate, or t-butylammonium
hydroxide. Volatile bases such as, for example, ammonia or volatile
lower alkyl amines, do not function as the fixed base of this
invention and do not contribute to the required degree of
neutralization by a fixed base, but may be used in addition to the
fixed base. Fixed multivalent bases such as, for example, calcium
carbonate may tend to destabilize an aqueous dispersion, if the
addition polymer is used in the form of an aqueous dispersion, but
may be used in minor amount.
[0055] When the formaldehyde-free aqueous composition comprises one
or more polyacids or polymeric polyacids not having hydroxyl group
containing monomers as copolymerized units, the compositions
further contain one or more polyol containing at least two hydroxyl
groups. The polyol should be sufficiently nonvolatile that it will
substantially remain available for reaction with the polyacid in
the composition during heating and curing. The polyol may be one or
more compound with a molecular weight of less than 1000 bearing at
least two hydroxyl groups. Suitable polyols include, for example,
ethylene glycol, glycerol, pentaerythritol, trimethylol propane,
sorbitol, sucrose, glucose, resorcinol, catechol, pyrogallol,
glycollated ureas, 1,4-cyclohexane diol, diethanolamine,
triethanolamine, dipropanolamine, diisopropanolamine,
triisopropanolamine, methyldiethanolamine, butyldiethanolamine and
methyldiisopropanolamine and certain reactive polyols such as, for
example, .beta.-hydroxyalkylamides such as, for example,
bis-[N,N-di(.beta.-hydroxyethyl)]adipamide, as may be prepared
according to the teachings of U.S. Pat. No. 4,076,917, hereby
incorporated herein by reference, or may include one or more
addition polymer containing at least two hydroxyl groups or active
hydrogen groups, such as, for example, polyvinyl alcohol, partially
hydrolyzed polyvinyl acetate, and addition homopolymers or
copolymers of hydroxyethyl (meth)acrylate, hydroxypropyl
(meth)acrylate, dialkylaminoalkyl (meth)acrylamide, and the
like.
[0056] The ratio of the number of equivalents of carboxy,
anhydride, or salts thereof in the curable aqueous binder
composition, i.e. of the polyacid, (co)polymeric polyacid or
copolymer, to the number of equivalents in the curable aqueous
binder composition, i.e. of hydroxyl in the polyol, or the
hydroxyl-group containing comonomer, or the copolymeric polyacid or
copolymer containing hydroxyl groups, ranges from 1/0.01 to 1/3. An
excess of equivalents of carboxy, anhydride, or salts thereof of
the polyacids, polymeric polyacid or copolymer to the equivalents
of hydroxyl in the polyol, polymeric polyacid or copolymer is
preferred. More preferably, the ratio of the number of equivalents
of carboxy, anhydride, or salts thereof in the in the curable
aqueous binder composition to the number of equivalents of hydroxyl
in the curable aqueous binder composition ranges from 1/0.2 to 1/1.
The most preferred ratio of the number of equivalents of carboxy,
anhydride, or salts thereof in the polyacids, polymeric polyacid or
copolymer or their mixtures to the number of equivalents of
hydroxyl in the polyol, polymeric polyacid or copolymer or their
mixtures ranges from 1/0.2 to 1/0.8.
[0057] In certain embodiments, the curable composition can include
one or more phosphorous-containing accelerator which can include
phosphorous-containing compounds such as, for example, alkali metal
hypophosphite salts, alkali metal phosphites, alkali metal
polyphosphates, alkali metal dihydrogen phosphates, polyphosphoric
acids, and alkyl phosphinic acids or can include oligomers or
polymers bearing phosphorous-containing groups such as, for
example, addition polymers of acrylic and/or maleic acid formed in
the presence of sodium hypophosphite, or the polymeric polyacid or
copolymer of the present invention prepared from ethylenically
unsaturated monomers in the presence of phosphorous salt chain
transfer agents or terminators, or addition polymers containing
acid-functional monomer residues such as, for example,
copolymerized phosphoethyl methacrylate, and like phosphonic acid
esters, and copolymerized vinyl sulfonic acid monomers, and their
salts. The phosphorous-containing species can be used at a level of
from 0% to 40%, preferably from 0% to 5%, further preferably from
0% to 2.5%, more preferably from 0% to 1%, and further more
preferably from 0% to 0.5% by weight based on the weight of the
polymer of the present invention.
[0058] In one embodiment of the invention, the formaldehyde-free
curable aqueous composition may contain a highly reactive polyol
without, or in addition to, the phosphorous-containing accelerator.
The highly reactive polyol may be mixed with polyacids or polyacid
(co)polymers or copolymers or may be part of the polyacid
(co)polymers or copolymers. The composition preferably includes a
highly reactive polyol such as, for example, a
.alpha.-hydroxyalkylamide of the formula:
[HO(R.sup.3).sub.2C(R.sup.2).sub.2C--N(R.sup.1)--C(O)--].sub.n-A-[--C(O)---
N(R.sup.1)--C(R.sup.2).sub.2C(R.sup.3).sub.2OH]n' (I)
[0059] wherein A is a bond, hydrogen or a monovalent or polyvalent
organic radical derived from a saturated or unsaturated alkyl
radical wherein the alkyl radical contains from 1-60 carbon atoms,
such as methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl,
nonyl, decyl, eicosyl, triacontyl, tetracontyl, pentacontyl,
hexylcontyl and the like; aryl, for example, mono and dinuclear
aryl such as phenyl, naphthyl and the like; tri-lower alkyleneamino
such as trimethyleneamino, triethyleneamino and the like; or an
unsaturated radical containing one or more ethylenic groups 2
[0060] such as ethenyl, 1-methylethenyl, 3-butenyl-1,3-diyl,
2-propenyl-1,2-diyl, carboxy lower alkenyl, such as
3-carboxy-2-propenyl and the like, lower alkenyl carbonyl alkenyl
such as 3-methoxycarbonyl-2-propenyl and the like; R.sup.1 is
hydrogen, lower alkyl of from 1-5 carbon atoms such as methyl,
ethyl, n-propyl, n-butyl, sec-butyl, tert-butyl, pentyl and the
like or hydroxy lower alkyl of from 1-5 carbon atoms such as
hydroxyethyl, 3hydroxypropyl, 2-hydroxypropyl, 4-hydroxybutyl,
3-hydroxybutyl, 2hydroxy-2-methylpropyl, 5-hydroxypentyl,
4-hydroxypentyl, 3hydroxypentyl, 2-hydroxypentyl and the isomers of
pentyl; R.sup.2 and R.sup.3 are the same or different radicals
selected from hydrogen, straight or branched chain lower alkyl of
from 1-5 carbon atoms or one of the R.sup.2 and one of the R.sup.3
radicals may be joined to form, together with the carbon atoms,
such as cyclopentenyl, cyclohexyl and the like; n is an integer
having a value of 1 or 2 and n' is an integer having a value of 0
to 2 or when n' is 0, a polymer or copolymer (i.e., n has a value
greater than 1 preferably 2-10) formed from the
.beta.-hydroxyalkylamide when A is an unsaturated radical.
Preferred reactive polyols are those of the foregoing Formula (I),
wherein R.sup.1 is H, lower alkyl, or
HO(R.sup.3).sub.2C(R.sup.2).sub.2C-- -, n and n' are each 1, -A- is
--(CH.sub.2).sub.m is 0-8, preferably 2-8, each case is H and the
other is H or a C.sub.1-C.sub.5 alkyl; for example,
HO--CH(R.sup.3)CH.sub.2--N(R.sup.1)--C(O)--(CH.sub.2).sub.m--C(O)--N(R.sup-
.1)--CH.sub.2CH(R.sup.3)OH (Ia)
[0061] wherein R.sup.1, R.sup.3, and m have the meanings just
given. Examples of the most preferred reactive polyols fall within
the formula:
(HO--CH(R.sup.3)CH.sub.2).sub.2N--C(O)--(CH.sub.2).sub.m--C(O)--N(CH.sub.2-
CH(R.sup.3)OH).sub.2 (Ib)
[0062] wherein R.sup.3 is limited to H in both cases or --CH.sub.3
in both cases. Specific examples falling within Formula Ib are
bis[N,N-di(.beta.-hydroxyethyl)]adipamide,
bis[N,N-di(.beta.-hydroxypropy- l)]azelamide,
bis[N-N-di(.beta.-hydroxypropyl)]adipamide,
bis[N-N-di(.beta.-hydroxypropyl)]glutaramide,
bis[N-N-di(.beta.-hydroxypr- opyl)]succinamide, and
bis[N-methyl-N-(.beta.-hydroxyethyl)]oxamide.
[0063] Other suitable highly reactive polyols include epoxy resins
or bisphenol epoxy resins, such as bisphenol A or bisphenol F epoxy
diglycidyl or polyglycidyl ethers, polyglycidyl esters,
polyglycidyl amines, multifunctional epoxy resins having two or
more epoxy or glycidyl groups, including polyol polyglycidyl
ethers, such as butanediol diglycidyl ethers, neopentyl glycol
diglycidyl ethers, pentaerythritol triglycidyl ethers, hexanediol
diglycidyl ethers, phenol and cresol novolaks and resoles, and
cycloaliphatic polyol diglycidyl ethers, such as tetrahydrophthalic
acid diglycidyl ether, and 3,4-epoxycyclohexanecarb- oxylic
acid-3',4' epoxycyclohexylmethyl ester.
[0064] In another embodiment the salts of the carboxyl groups are
salts of functional alkanolamines with at least two hydroxyl groups
such as, for example, diethanolamine, triethanolamine,
dipropanolamine, and diisopropanolamine.
[0065] In yet another embodiment, the polyol and the
phosphorous-containing accelerator may be present in the same
addition polymer. In yet another embodiment the polymeric polyacids
or copolymer, the polyol, and the phosphorous-containing
accelerator may be present in the same addition polymer. As
disclosed above, the carboxyl groups of the polyacid may be
neutralized to an extent of less than 35% with a fixed base before,
during, or after the mixing to provide the aqueous composition.
Neutralization may be partially or wholly effected during the
formation of the polyacid.
[0066] In yet still another embodiment, a higher level of water
proofing of substrates may be achieved by adding one or more
emulsion polymer including, as copolymerized units, greater than 30
wt. %, preferably greater than 40 wt. %, more preferably greater
than 50 wt. %, and even more preferably greater than 60 wt. %,
based on the weight of the emulsion polymer solids, of an
ethylenically unsaturated acrylic monomer including a C.sub.5 or
greater alkyl group. By "emulsion polymer" herein is meant one or
more polymer dispersed in aqueous media that has been prepared by
emulsion polymerization. By "acrylic monomer including a C.sub.5 or
greater alkyl group" herein is meant one or more acrylic monomer
bearing an aliphatic alkyl group having five or more C atoms, the
alkyl group including n-alkyl, s-alkyl, i-alkyl, and t-alkyl
groups. Suitable ethylenically unsaturated monomers including a
C.sub.5 or greater alkyl group include (C.sub.5-C.sub.30) alkyl
esters of (meth)acrylic acid, such as amyl (meth)acrylate,
2-ethylhexyl (meth)acrylate, benzyl (meth)acrylate, lauryl
(meth)acrylate, oleyl (meth)acrylate, palmityl (meth)acrylate,
stearyl (meth)acrylate; unsaturated vinyl esters of (meth)acrylic
acid such as those derived from fatty acids and fatty alcohols;
surfactant monomers including long chain alkoxy- or
alkylphenoxy(polyalkylene oxide) (meth)acrylates, such as
C.sub.18H.sub.37-(ethylene oxide).sub.20 methacrylate and
C.sub.12H.sub.25-(ethylene oxide).sub.23 methacrylate; N-alkyl
substituted (meth)acrylamides such as octyl acrylamide; and the
like. The monomer including a C.sub.5 or greater alkyl group can
also contain functionality, such as amido, aldehyde, ureido,
polyether and the like, but preferably does not contain an acid or
hydroxy group. Emulsion polymers containing such monomers can be
prepared by emulsion polymerization, preferably by the method for
forming polymers of U.S. Pat. No. 5,521,266.
[0067] The emulsion polymer can also include, as copolymerized
units, from 0 to 10 wt. %, preferably from 0 to 5 wt. %, based on
the weight of the emulsion polymer solids, monomer bearing a
carboxylic acid group, anhydride group, or salt thereof or
hydroxyl-group, such as (meth)acrylic acid and hydroxyethyl
(meth)acrylate.
[0068] The emulsion polymer is present in an amount of from 1 to 10
wt. %, preferably from 1.5 to 5 wt. %, by weight based on the sum
of the weight of the polyacid and the weight of the polyol, all
weights being taken on a solids basis.
[0069] The curable composition can contain, in addition,
conventional treatment components such as, for example,
emulsifiers, pigments, fillers, anti-migration aids, curing agents,
coalescents, surfactants, particularly nonionic surfactants,
biocides, plasticizers, organosilanes, such as alkoxy silanes, like
aminopropyltri(m)ethoxy silane or glycidylpropyltri(m)ethoxy
silane, anti-foaming agents, corrosion inhibitors, particularly
corrosion inhibitors effective at pH<4 such as thioureas,
oxalates, and chromates, colorants, waxes, polyols which are not
polymers of the present invention such as glycerol, alkanolamines,
and polypropyleneglycol, other polymers not of the present
invention, and anti-oxidants. However, the total amount of filler
plus extender should not exceed 40% because the cured composition
that results will not retain acceptable hot wet tensile
strength.
[0070] The formaldehyde-free curable aqueous composition may be
prepared by admixing water or aqueous carrier with copolymer or
copolymeric polyacid, or with the polyacid or polymeric polyacid
and the polyol, or mixtures thereof, and, if desired, the
phosphorous-containing accelerator using conventional mixing
techniques. Where one or more emulsion is added, the curable
aqueous composition may be formed by adding the emulsion polymer to
the mixture of the copolymer, polyacid and the polyol, copolymeric
polyacid, or polymeric polyacid and polyol, or mixtures thereof,
which mixture may be at a pH of from 2.0 to 4.5. Agglomeration of
the emulsion polymer under these conditions can occur if the
emulsion polymer is not sufficiently stable; agglomeration is
believed to be undesirable for processing and efficiency reasons.
To achieve stability under these conditions in some embodiments it
is optionally preferred to add one or more surfactant to the
emulsion polymer before or during the addition of the emulsion
polymer to the mixture of the copolymer, (co)polymeric polyacid,
and/or polyacid and polyol. Preferred is the addition of from 0.5%
to 20%, preferably from 2% to 10%, by weight, based on the weight
of emulsion polymer solids. Preferred is one or more surfactant
having a HLB value of greater than 15.
[0071] In one aspect of the present invention a method for treating
one or more substrate is provided. Such treatments can be commonly
described as, for example, coating one or more substrate, sizing
one or more substrate, saturating one or more substrate, bonding
one or more substrate, and the like. Typical substrates include
wood such as wood particles, fibers, chips, flour, pulp, and
flakes; metal; plastic; fibers; woven and nonwoven fabrics; paper
oil- and air-filter stock, rayon nonwoven wipes, polyester/cotton
woven fabrics, cellulosic laminating stock, nonwoven cellulosic
felts, and wood fibers and flakes consolidated into or suitable to
be consolidated into fiberboard, hardboard, particleboard, oriented
strand board, and the like.
[0072] The curable composition can be applied to a substrate by
conventional techniques such as, for example, air or airless
spraying, padding, saturating, roll coating, curtain coating,
beater deposition, coagulation, or the like.
[0073] In one embodiment of this invention the curable composition
can be used as a binder for heat-resistant nonwoven fabrics such
as, for example, nonwovens which contain heat-resistant fibers such
as, for example, aramid fibers, ceramic fibers, metal fibers,
carbon fibers, polyimide fibers, certain polyester fibers, rayon
fibers, rock wool, and glass fibers. By "heat-resistant fibers"
herein is meant fibers which are substantially unaffected by
exposure to temperatures above 125.degree. C. Heat-resistant
nonwovens can also contain fibers which are not in themselves
heat-resistant such as, for example, certain polyester fibers,
rayon fibers, nylon fibers, and superabsorbent fibers, in so far as
they do not materially adversely affect the performance of the
substrate.
[0074] Nonwoven fabrics are composed of fibers which can be
consolidated by purely mechanical means such as, for example, by
entanglement caused by needle-punching, by an air-laid process, and
by a wet-laid process; by chemical means such as, for example,
treatment with a polymeric binder; or by a combination of
mechanical and chemical means before, during, or after nonwoven
fabric formation. Some nonwoven fabrics are used at temperatures
substantially higher than ambient temperature such as, for example,
glass fiber-containing nonwoven fabrics which are impregnated with
a hot asphaltic composition pursuant to making roofing shingles or
roll roofing material. When a nonwoven fabric is contacted with a
hot asphaltic composition at temperatures of from 150.degree. C. to
250.degree. C., the nonwoven fabric can sag, shrink, or otherwise
become distorted. Therefore, nonwoven fabrics which incorporate a
curable composition should substantially retain the properties
contributed by the cured aqueous composition such as, for example,
tensile strength. In addition, the cured composition should not
substantially detract from essential nonwoven fabric
characteristics, as would be the case, for example, if the cured
composition were too rigid or brittle or became sticky under
processing conditions.
[0075] Heat treatment at from 120.degree. C. to 400.degree. C. for
a period of time from 3 seconds to 15 minutes may be carried out;
treatment at 150.degree. C. to 225.degree. C. is preferred, and,
when using the phosphorous containing accelerator or reactive
polyol, heat treatment at 150.degree. C. to 200.degree. C. is
preferred. The drying and curing functions may be effected in two
or more distinct steps, if desired. For example, the composition
may be first heated at a temperature and for a time sufficient to
substantially dry but not to substantially cure the composition and
then heated for a second time at a higher temperature and/or for a
longer period of time to effect curing. Such a procedure, referred
to as "B-staging", may be used to provide binder-treated nonwoven,
for example, in roll form, which may at a later stage be cured,
with or without forming or molding into a particular configuration,
concurrent with the curing process.
[0076] The heat-resistant nonwovens may be used for applications
such as, for example, insulation batts or rolls, as reinforcing
mats for roofing or flooring applications, as roving, as
microglass-based substrates for printed circuit boards or battery
separators, as filter stock, as tape stock, and as reinforcement
scrim in cementitious and non-cementitious coatings for
masonry.
[0077] The treated cellulosic substrates may be used for
applications such as, for example, laminates, industrial wipes,
durable-press clothing, and oil and air filters, and consolidated
wood products.
[0078] Nonwoven cellulosic wipes are beneficially strengthened
under dry, water-wet and solvent-wet conditions which may be met in
their use.
[0079] Oil- and air-filter stock is beneficially strengthened to
give the composite integrity at high temperatures, and in the case
of oil-filter applications, when saturated with hot oil.
[0080] The following examples are intended to illustrate the
curable composition and the use thereof in the method for treating
substrates.
EXAMPLES
[0081] Treatment of Glass Microfiber Filter Paper and Tensile
Testing of Treated Substrate
[0082] Aqueous curable compositions were prepared with various
amounts of a commercially available acrylic thermoset TSET.TM. No.
1, a mixture of poly(acrylic acid), triethanolamine and sodium
hypophosphite, available from Rohm and Haas Company, Philadelphia,
Pa. (53 wt. % solids in water, mfg. in U.S.A. between March, 2002
and March, 2004) mixed with extender. The comparative binder
comprised a commercially available ACRONAL.TM. 2438 acrylic-maleic
copolymer thermoset, available from BASF Aktiengesellschaft,
Ludwigshafen, Germany (obtained June, 2002). The pH of the aqueous
binder dispersions or solutions was adjusted to pH 3 with sulfuric
acid and the solutions or dispersions were diluted to 200 g. with
water providing a weight 5% solids mixture (Table 1). Glass
microfiber filter paper sheets, GF/A (glass type A),
(20.3.times.25.4 cm, for example, Cat No. 1820 866, Whatman
International Ltd., Maidstone, England) were drawn through a trough
containing a pre-mixed binder solution that has been further mixed
by agitation. The coated paper samples were then sandwiched between
two cardboard sheets to absorb excess binder, and pressed between
the two cardboard sheets in a Birch Brothers Laboratory Patter set
at a speed setting of 5 and at a pressure of 10 psi (68.9476 kPa).
The coated sheets were then dried by heating at 90.degree. C. for
90 sec in a vented Mathis oven. Post drying weight was determined
to calculate binder add-on (dry binder weight as a percentage of
filter paper weight). The dried sheets were then cured in a vented
Mathis oven at the times and temperatures specified in Table 2.
[0083] The cured sheets were cut into 1 inch (2.54 cm) (cross
machine direction) by 4 inch (10.16 cm) (machine direction) strips
and tested for tensile strength in the machine direction in a
Thwing-Albert Intelect 500 tensile tester. IN tensile strength
testing, the fixture gap was set at 2 inches (5.08 cm) and the pull
rate was set at 2 inches/minute (5.08 cm/minute). Strips were
tested either dry (dry tensile) or immediately after a 10 or 30
minute soak in water at 85.degree. C. (10 min and 30 min wet
tensile, respectively.) The tensile strengths in Table 2 were
recorded as the peak force measured during parting or breaking each
tested strip in two. Each point of the data reported is an average
of seven test strips separately tested.
1TABLE 1 Sample Formulations % Extender on Binder Type Identity A1
0 Standard B1 10 Talc MISTRON .TM. 353.sup.6 B2 20 Talc MISTRON
.TM. 353.sup.6 C1 10 Clay.sup.1 ASP .TM. 400.sup.1 C2 20 Clay.sup.1
ASP .TM. 400.sup.1 D1 10 Silica.sup.2 IMSIL .TM. A-10.sup.7 D2 20
Silica.sup.2 IMSIL .TM. A-10.sup.7 E1 10 Silica.sup.3 CELITE .TM.
281 E2 20 Silica.sup.3 CELITE .TM. 281 F1 10 Feldspar Minspar
3.sup.10 F2 20 Feldspar Minspar 3.sup.10 G1 10 Kaolin NEOGEN .TM.
EFP.sup.11 G2 20 Kaolin NEOGEN .TM. EFP.sup.11 A1' 0 Standard G1'
20 Kaolin NEOGEN .TM. EFP.sup.11 G3 30 kaolin NEOGEN .TM.
EFP.sup.11 H1 20 Kaolin NEOGEN .TM. 2000.sup.11 H2 30 Kaolin NEOGEN
.TM. 2000.sup.11 I1 20 1 nm .times. 200 nm.sup.4 Montmorillonite I2
30 1 nm .times. 200 nm.sup.4 Montmorillonite D2' 20 Silica.sup.2
IMSIL .TM. A-10.sup.7 D3' 30 Silica.sup.2 IMSIL .TM. A-10.sup.7 J1
20 Clay.sup.1 ASP .TM.-170.sup.1 J2 30 Clay.sup.1 ASP
.TM.-170.sup.1 K1 20 Silica.sup.2 SILVER BOND .TM. B.sup.12 K2 30
Silica.sup.2 SILVER BOND .TM. B.sup.12 L1 20 Bentonite.sup.5
BENTOLITE .TM. .sup.8 L2 30 Bentonite.sup.5 BENTOLITE .TM. .sup.8 M
0 ACRONAL .TM. 2438 (BASF) N1 20 (ACRONAL .TM.) Silica.sup.2 SILVER
BOND .TM. B.sup.12 N2 30 (ACRONAL .TM.) Silica.sup.2 SILVER BOND
.TM. B.sup.12 O1 20 (ACRONAL .TM.) Silica.sup.2 IMSIL .TM.
A-10.sup.7 O2 30 (ACRONAL .TM.) Silica.sup.2 IMSIL .TM. A-10.sup.7
P1 20 (ACRONAL .TM.) Bentonite.sup.5 BENTOLITE .TM. .sup.8 P2 30
(ACRONAL .TM.) Bentonite.sup.5 BENTOLITE .TM. .sup.8
.sup.1Anhydrous aluminosilicate clay delaminated Engelhard Corp.,
Iselin, NJ; (ASP-400 .TM.: Plates/laminates of mean particle size
4.8 .mu.m; 10% aq. slurry -pH of 4.2; ASP-170 .TM.: Ultrafloated
plates of mean particle size 0.55 .mu.m - 10% aq. slurry- pH of
7.0) .sup.2Microcrystalline silica .sup.3Diatomaceous silica (6
.mu.m mean particle size) .sup.4Primary particle size of exfoliated
platelets .sup.5A colloidal clay comprising montmorillonite
.sup.6Sierra Talc and Clay Co., Los Angeles, CA .sup.7Illinois
Minerals Company, Cairo, IL (silica micronized: 2.4 .mu.m mean
particle size) .sup.8Southern Clay Products, Inc., Gonzales, TX
.sup.9Johns-Manville Corp., Denver, CO .sup.10Kentucky-Tennessee
Clay Co., Nashville, TN .sup.11Dry Branch Kaolin Co., Dry Branch,
GA .sup.12Unimin Specialty Minerals Inc., New Canaan, CT (silica
micronized - 9 .mu.m mean particle size)
[0084] In Table 2, we obtained data on samples prepared with a 30
second cure, which data we do not use to define the ratio of
hot-wet tensile strength to dry tensile strength, as used herein.
We provided those data simply to show advantages of this
invention.
2TABLE 2 Tensile Strength of Binder and Extended Binder: Tensile
Strengths of Treated Glass Microfiber Filter Paper Tensile Strength
(lbf) after Tensile Strength (lbf) after 30 sec cure 60 sec cure
Cure 10 min 30 min add- 10 min 30 min add- Sample Temp dry wet wet
on dry wet wet on A1 210 8.8 6.0 5.0 11.0% 9.0 6.3 5.6 11.0% B1 210
8.6 4.9 4.9 11.3% 8.1 6.2 4.2 11.4% B2 210 9.0 5.4 4.7 11.8% 7.6
6.5 4.8 11.8% C1 210 6.4 5.4 5.4 12.0% 7.2 5.5 4.6 12.3% C2 210 8.0
5.7 5.0 12.2% 6.8 5.8 5.5 12.5% D1 210 8.6 5.6 5.2 12.7% 8.7 5.4
4.8 12.4% D2 210 9.4 5.8 5.1 12.2% 8.6 6.0 5.5 12.3% E1 210 8.3 4.7
4.5 11.2% 8.7 5.7 4.0 11.0% E2 210 9.1 5.9 5.0 11.7% 8.4 6.1 5.0
11.9% F1 210 8.2 5.8 3.3 11.1% 8.8 6.3 4.8 10.7% F2 210 9.0 6.5 3.7
11.2% 8.7 6.9 5.0 10.8% G1 210 8.1 6.2 4.7 11.3% 7.6 6.1 5.3 10.7%
G2 210 10.6 5.9 5.3 11.6% 9.3 5.8 5.4 11.6% A1' 210 10.2 7.5 6.9
10.6% 10.5 7.5 7.0 11.0% G1' 210 9.2 7.5 6.3 11.6% 9.3 7.4 6.1
11.2% G3 210 9.5 5.5 6.0 12.2% 9.1 6.0 6.0 11.8% A1' 210 10.2 7.5
6.9 10.6% 10.5 7.5 7.0 11.0% H1 210 9.1 6.1 5.1 14.2% 8.5 6.0 5.8
13.7% H2 210 9.1 5.8 5.2 13.7% 9.2 6.3 5.5 14.2% I1 210 8.6 6.7 5.7
11.1% 9.9 7.4 6.4 10.6% I2 210 8.0 6.9 5.5 10.5 9.4 7.2 6.1 11.2%
D2' 210 9.9 7.9 7.6 13.3 9.1 7.9 7.7 13.8% D3' 210 7.5 7.4 5.7
14.8% 9.2 7.2 6.3 13.7% J1 210 8.6 7.4 7.2 14.2% 9.6 7.1 6.1 13.7%
J2 210 9.9 6.9 6.5 13.6 9.4 7.2 7.4 14.4% K1 210 10.7 7.6 6.8 12.6%
11.0 7.6 7.5 12.5% K2 210 9.6 7.2 7.4 11.8% 9.8 7.7 6.8 13.0% L1
210 10.3 7.9 5.5 11.8% 10.5 8.1 4.7 11.1% L2 210 9.2 7.1 5.5 10.4%
9.4 7.9 4.9 10.7% M 210 9.0 4.5 13.3% N1 210 7.9 3.5 13.0% N2 210
8.3 3.5 12.6% O1 210 8.9 3.9 13.4% O2 210 8.6 4.4 14.4% P1 8.3 3.4
13.1% P2 8.4 2.8 13.3%
[0085] Wet tensile strength of a curable composition-treated glass
microfiber filter paper which is a substantial fraction of dry
tensile strength of a similarly treated glass microfiber filter
paper is taken herein to indicate that a composition has cured, and
that useful high temperature performance of the cured aqueous
composition-treated glass microfiber filter paper results.
Extenders that do not alter wet tensile strength by 50% or more are
valued for this invention. As shown in Table 3, below, the best
hot-wet tensile over dry tensile strengths are shown by the various
silicas, especially microcrystalline silica, bentonite, and
delaminated aluminosilicate clay, followed by kaolin. Extenders
giving the best tensile strength, particularly at high loading, are
the various silicas.
[0086] We found that upon soaking the paper in the binder solution,
we obtained an "add on" of binder to the paper of approximately
11%, but with a small amount of variability. In our definition of
"wet over dry tensile strength" we simply perform the soaking as
defined, and whatever add on that is obtained is inherent in the
test itself. Because we are using a ratio, the slight variability
that might result in a measured tensile strength is cancelled out
because each of the two strengths in the ratio will have the same
variability. Accordingly, the use of a ratio removes much, if not
all of the effects of add on variability. Similarly, the use of a
ratio approach should remove the effect of slight variations in
substrate type (e.g., which type of fiberglass filter paper to
use).
3TABLE 3 *Hot-Wet Strength (30 min. soak at 85.degree. C.)/Dry
strength .times. 100% % Hot- Hot- Example wet/dry wet/dry A1 66.7
0.667 B1 51.9 0.519 B2 63.2 0.632 C1 63.9 0.639 C2 80.9 0.809 D1
55.2 0.552 D2 64.0 0.640 E1 46.0 0.460 E2 59.5 0.595 F1 54.5 0.545
F2 57.5 0.575 G1 69.7 0.697 G2 58.1 0.581 A1' 66.7 0.667 G1' 67.8
0.678 G3 65.9 0.659 H1 68.2 0.682 H2 59.8 0.598 I1 64.6 0.646 I2
64.9 0.649 D2' 84.6 0.846 D3' 68.5 0.685 J1 63.5 0.635 J2 78.7
0.787 K1 68.2 0.682 K2 69.4 0.694 L1 58.0 0.580 L2 52.1 0.521 M1
50.0 0.500 N1 44.3 0.443 N2 42.2 0.422 O1 43.8 0.438 O2 51.2 0.512
P1 41.0 0.410 P2 33.3 0.333 *Cured at 210.degree. C. for 60
seconds
* * * * *