Note: Descriptions are shown in the official language in which they were submitted.
~. CA 02217725 2003-04-30
STORAGE STABLE ONE-POT AQUEOUS SILYLATED POLYMER
CURABLE COMPOSITIONS
BACKGROUND OF THE INVENTION
The present invention relates to storage stable curable polymer compositions
and a process for preparing such compositions.
Water-curable compositions based on thermoplastic polymers having
hydrolyzable silane moieties are becoming increasingly interesting as
environmental, health
and safety concerns increase for other curing technologies. Such compositions
have
excellent properties of weather-, chemical- andwater-resistance, since the
alkoxysilyl group
is connected to the polymer chain by a carbon-silicon bond, rather than a
labile carbon-
oxygen-silicon linkage; therefore water-, alkali- and acid-resistance are
remarkably
improved compared to a system with silicates or silanes added by physical
mixing. One
disadvantage of water-curable silylated polymer compositions, however, is that
they tend to
crosslink, especially if dispersed in water, under normal conditions of
preparation, handling
and storage. As a result, the relatively poor shelf life of such compositions
has tended to
limit their wide commercial acceptance and has kept the use of silylated
polymers to those
with very low silane concentrations, typically less than 1.0 weight percent,
in waterborne
polymeric products.
Modification of water-curable compositions to alleviate the problem of
premature crosslinking is described in U.S. Pat. No. 4,526,930 which teaches
relatively
water-stable, melt-processable, thermoplastic polymers with hydrolyzable
silane moieties.
These silyated polymers are only activated or made readily water-curable by
the reaction
therewith of an organotitanate having at least one readily
CA 02217725 2003-04-30
hydrolyzable group, which ester exchanges with an ester group of the silane.
Although the titanate functions as a silanol condensation catalyst, it is
dispersed in the
alkylene-acrylate solid matrix, not in water.
Unexamined Japanese Patent Publication No. 6025502 teaches a
composition comprising a polymer emulsion obtained by adding a tin catalyst (a
diorganotin carboxylate) which is insoluble in water, to silylated vinyl
polymers after
emulsion polymerization. The addition of a water insoluble tin catalyst,
however, is not
suitable for such films because defects result from the heterogeneous
catalysts and
the emulsion polymer mixtures, such as formation of craters and granular
particles on
the surface and uneven crosslinkage in the film structure. Moreover, the
silanes
taught therein have alkoxy groups of at least eight carbons long and generally
of a
straight chain.
This Japanese patent application also teaches non-discriminate curing
catalysts generally used for silanelester hydrolysis and condensation
reactions.
Similar examples of catalysts for silane ester and silanol-containing
compositions can
be found in the literature, which disclose catalysts dissolved in organic
solvent-based
systems to ensure a proper cure.
For example, it has long been known that diorganotin dicarboxylates are
catalysts for polymerization of organosilicon compounds. However, in spite of
their
proven utility, the diorganotin dicarboxylates suffer from several
disadvantages. One
is the relative instability of the compound as shown by loss of activity upon
standing,
particularly under moist conditions. The phenomenon is even more pronounced
when
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the catalyst is in the form of an aqueous emulsion. Many tin compounds may
also
undergo hydrolysis during prolonged storage and revert to catalyticafly
inactive forms.
Thus, it is clear that there is the need for one component, water-based
dispersed silylated polymeric systems that have good stability during storage
in water
and which produce films of good quality upon application and drying.
SUMMARY OF THE INVENTION
The present invention provides compositions and methods of preparing
and methods of using water dispersible or emulsifiabfe, curable polymers
having at
least one alkoxy silane hydrolyzabfe group and which clearly meet the
challenges of
the above problems. The present invention relates to the compositions and
methods
of making compositions of silylated polymers, curable by organometallic
catalysts, and
which have good stability during storage in water. These compositions also
include a
catalyst, water and optionally, some other ingredients. The compositions may
be used
in coatings, adhesive and sealants. An exemplary use is in fiberglass sizing.
Said compositions have shelf lives of at least twelve months. More
preferably, these compositions have shelf lives of at least 24 months.
BRIEF DESCRIPTION OF THE FIGURES
Figure 1 represents photographs of vinyl acrylic latex coatings cured by
hydrolyticafly stable water miscible and water dispersible catalysts on
stainless steel.
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Figure 2 represents photographs of vinyl acrylic latex coatings cured by
hydrolytically stable water insoluble catalysts on stainless steel.
DETAILED DESCRIPTION OF THE INVENTION
The curable, aqueous compositions of the present invention comprise:
(I) a stable, water dispersible or emulsifiable, curable polymer containing a
sterically
hindered alkoxylated silane group at 0.1 to 75 weight percent of the total
composition;
(1l) water dispersible or water soluble organometallic catalyst(s), at 0.1 to
10 weight
percent of the total composition; (Ill) water at 99.8 to 24.9 weight percent;
and
optionally, (IV) other ingredients.
(I) Pol
Polymers for use herein are water dispersible or emulsifiabte, curable
polymers which have pendant and/or terminal silyl ester groups (i.e., alkoxy
silane)
thereon, where at least some of the pendant and/or terminal silyl ester groups
are
silanes which are sterically hindered. The steric hindrance of the silyl ester
prevents
hydrolysis of the silane ester and allows for longer shelf-life. The silane
monomer
portion of the polymer should be present at 0 1 to 50 mole percent of the
monomers
used to form the polymer. Varying the amount of silane in the polymer affects
the
performance properties of the composition.
The polymer may be added to water as an emulsion or dispersion. If the
r
polymer is an emulsion, some amount of emulsifier will be required.
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The polymers for use herein include, but are not limited to, vinyls,
acrylics, vinyl acrylics, polyurethanes, polyamides, epoxies, polystyrenes,
polyesters,
vinyl esters, polyolefins, polyethylene, polypropylene and alkyds. Copolymers
using at
least two different monomers may also be used. The silyl ester group (i.e.,
R3SiR2a(OR')3.a) is most commonly attached to the polymer through an alkylene
. group. The polymers should have molecular weights of between 1,000 and three
million.
Illustrative examples of monomeric organofunctional silanes for
incorporation into the polymer when free radical addition polymerization is
used
include acrylatoalkylalkoxysilanes, methacrylatoalkylalkoxysilanes or vinyl
alkoxysilane
monomers, such as 3-methacryloxypropyltri-iso-propoxysilane, 3-
methacryloxypropyltri-iso-butoxysilane, 3-methacryloxypropyltrioctoxysilane,
vinyltri-
iso-butoxysilane, vinyl tri-n-decoxysilane and vinyltri-tert-butoxysilane.
Other
polymerizable silanes, such as maleates, may be used. Silyl-terminated
polymers are
formed by reacting chain transfer agents, such as 3-mercaptopropyl tri-iso-
butoxysilanec.
Illustrative examples of monomeric organofunctional silanes for
incorporation into the polymer when the polymer is formed by condensation
polymerization include 3-aminopropyltri-iso-propoxy silane, N-(2-aminoethyl)-
3-
aminopropyldi-iso-butoxy silane, 4-mercaptobutyldimethyloctyloxysilane, 3-
isocyanatopropyltri-seo-butoxysilane, and 3-
glycidoxypropylmethyldipentoxysilane.
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Polymers that are formed by condensation polymerization include polyurethanes,
epoxies, polyesters, vinyl esters, polyureas, polyamides and similar types of
polymers.
The silanes may be grafted or end-capped onto an existing polymer or
may be a co-monomer in the production of the polymer.
Further, the pendant and/or terminal silane group of the polymer may be
represented by the structure R2a(R'O)3-aSiR3 where R' is a sterically hindered
C3 to Cia
alkyl group in straight or branched chain configuration; R2 is a monovalent
hydrocarbon group having from one to ten carbon atoms; R3 is an alkylene,
arylene,
aryalkylene group or the polymer backbone itself, with the proviso that the
SiR3 is
bound to the polymer through an Si-C bond; and "a" has a value of zero, one or
two.
Illustrative of suitable stericaily-hindered, straight chain hydrocarbon
radicals for use as R' in the formula set forth above are n-butyl, n-pentyl n-
hexyl, n-
heptyl, n-octyl, n-nonyl, n-decyl and the like, and cyclo-radicals such as
cyclopentyl,
cyclohexyl, cycioheptyl, cyclooctyl, bicycloheptyl, and the like. illustrative
of suitable
branched chain hydrocarbon radicals for Ri are alkyl radicals such as iso-
octyl, 1-
ethyl, 3-methyl pentyl, 1,5 di-methyl hexyl, 4-methyl-2-pentyl and the like.
The most
preferable R' are sterically hindered groups of less than five carbons, and
more
preferably less than four carbons, such as isopropyl, seo-butyl, iso-butyl and
seo-amyl.
R2 is a monovalent hydrocarbon having from one to ten carbon atoms,
for example, an alkyl group (e.g., methyl, ethyl, propyl, octyl or decyl) or
an aryl group
(e.g., phenyl, benzyl or tolyl). R3 is the group that finks the silane pendant
or terminal
group to the polymeric backbone and may be a straight or branched alkyl group,
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arylalkyl group or aryl group, generally has about from 1 to 18 carbons and
may nave
substituents thereon or may be the polymer itself. The silicon atom is bound
to the
polymer through a silicon carbon bond, on R3, which provides hydrolytic and
thermal
stability to the silylated polymer.
Substituents to the R3 group may include a replacement for a carbon atom with
atoms
such as oxygen, nitrogen or sulfur, with the proviso that the carbon atom
adjacent to
the silicon is not replaced. Other substituents include replacement of the
hydrogen
atom attached to carbon with halogen atoms, nitrogen, sulfur, oxygen, and
organofunctional groups, such as cyano, urea, esters, amides, oxo and the
like.
The polymers may be prepared by any polymerization technique known
in the art, such as, suspension polymerization, interfacial polymerization,
solution
polymerization or emulsion polymerization. Emulsion polymerization of
ethyienically
unsaturated monomers in the presence of certain surfactants is the preferred
polymerization technique for vinyl and acrylic polymers because the aqueous
dispersion of latex polymer particles so formed can be used directly or with
minimal
work-up in preparing the aqueous compositions of the present invention. These
poiymerizations may be conducted as is well known in the art.
Polymers suitable for dispersing in water usually incorporate solubilizing
groups, such as nonionic, anionic, or cationic groups. Nonionic groups include
amino,
hydroxyl, carboxyl, polyalkylene oxide and the like. Anionic groups include
salts of
sulfates, phosphates, carboxyiates and the like. Cationic groups include
protonated
amines, quaternary ammonium salts and the like. Combinations of the above
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solubilizing groups of nonionic with either cationic or anionic groups may be
used.
Polymer dispersions may be prepared by techniques well known in the art.
Emulsions Qf polymers that contain a silyl group with sterically hindered
alkoxy groups can be prepared by using emulsifiers and techniques welt
known.in the
art. The emulsifiers for use herein include nonionic, anionic and cationic
surfactants
. or mixtures of nonionic with anionic or cationic surfactants. Examples of
the
nonionic surfactants include polyoxyethylene alkyl ethers, polyoxyethylene
alkyl
phenyl ethers, polyoxyethylene fatty acid esters, sorbitan fatty acid esters,
and
polyoxyethylene sorbitan fatty acid esters. Examples of the anionic
surfactants
include fatty acid salts, alkyl sulfate ester salts, alkyl benzene sulfonate,
alkyl
phosphate, alkylallyl sulfate ester salt, and polyoxyethylene alkylphosphate
ester.
Examples of the cationic surfactants include quaternary ammonium salts such as
long chain alkyl trimethylammonium salts, long chain alkyl benzyl dimethyl
ammonium salts, and di(long chain alkyl) dimethyl ammonium salts. A further
listing
of surfactants useful in the present invention may be those described in 1994
McCutcheon's Vol 1: Emulsifiers and Deter4ents, North American Edition (The
Manufacturing Confectioner Publishing Co., Glen Rock) 1994.
The emulsifiers) should be present in the range of 0.05 to 30 weight percent
based on weight of polymer and preferably 0.2 to 20 weight percent of the
polymer
composition.
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The appropriate HLB (hydrophilic-fipophilic balance) of the surfactants is
chosen to correspond to the HLB of the specific silylated polymer being
emulsified.
The method for selecting the optimum HLB for a substance is well known to one
skilled in the art and described in "The HLB System" by ICI Americas Inc.
The stable, water dispersible or emulsifiable, curable polymer containing a
stericaily hindered alkoxylated silane group should be present at 0.1 to 75
percent
by weight of the total composition.
(I I~Catalyst
The present invention solves the problems of the prior art by using water
soluble or emulsifiabie curing catalysts, not previously used with aqueous
compositions of silylated polymers, to cure such polymers. Suitable catalysts
for use
herein are hydrolytically stable, water emulsifiable or water soluble
organometallic
catalysts, such as hydrolyticaily stable organotitanate, organotin, chelated
titanium,
aluminum and zirconium compounds, and combinations thereof.
Hydroiytically stable means that the organometallic catalyst is sufficiently
stable
in the presence of water at a pH between 5.5 and 8.5 such that less than 50
percent of
the organometaiiic catalyst loses its catalytic activity in a period of twelve
months. The
catalytic activity of the organometallic catalyst is lost due to the
disassociation of the
covalently bonded and/or coordinately bonded ligand(s) into the water which
results in
the catalyst precipitating from solution or forming inactive metallic species,
such as
metallic oxides.
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Water soluble means having a solubility of greater than 2 weight percent of
water at room temperature. It is noted that water emulsifiable catalysts will
require the
addition of an emulsifier. The emulsifiers and method of emulsion preparation
are the
same as those described for emulsifying the polymer with the proviso that the
emulsifiers used to make emulsions of the catalysts are compatible with the
emulsifiers used to make emulsions of the polymer. Water soluble catalysts are
preferred over water emulsifiable catalysts because it is possible that the
emulsifiable
catalysts may settle during standing and affect the cure and properties of the
composition.
The genera! structure of the organometallic catalysts for use herein is
represented by :R4bML~ where M is a transition metal ion, such as titanium,
tin,
aluminum or zirconium, R4 is a monovalent hydrocarbon group having from one to
ten
carbon atoms; L may each be the same or different and are ligands that are
covalently
or coordinately bonded to the metal ion; b has a value of zero to four; and c
has a
value of one to six, with the proviso that b + c is between two and six.
Exemplary R4 are alkyls (e.g., methyl, ethyl, octyl or decyl}, aryls (e.g.,
phenyl or napthyl), substituted aryls (e.g., chiorophenyl, tolyl or
cyanophenyi) or
aralkyls (e.g., benzyl or phenylethyl}. Exemplary L's are sulfur, mercaptides,
water,
hydroxyl, ammonia, amide or preferably a heteroatom unsubstituted alkylene,
arylene
or aralkylene group having from one to twenty carbons which have substituents
thereon and may have heteroatoms such as oxygen, nitrogen or sulfur. The
substituents include halogens, nitrogen, sulfur, oxygen, cyano, urea, ester,
amide, and
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similar groups. L may contain more than one heteroatom capable of covalently
bonding with the metal ion.
The general structure of titanate chelates for use herein are represented
bY
RIO X Y
O Ti O
Y X OR4
in which X represents a functional group containing oxygen or nitrogen, and Y
represents a an alkyl chain having from 1 to 10 carbons and R4 represents a
hydrogen
or an alkyl, aryl or aralkyl group having from 1 to i 0 carbons.
Examples of soluble chelated titanates and aqueous chelated titanates
are dihydroxy bis [2-hydroxypropanato {2-)-O',02j titanate, mixed titanium
ortho ester
complexes, acetylacetonate chelate, bis(ethyl-3-oxobutanolato-01,03) bis(2-
propanolato) titanium, and alkanolamine complex of titanium. Other
hydrolytically
stable titanium catalysts are listed in Feld et al., 'The Chemistry of
Titanium" (1965).
Preferred catalysts are TYZOR~i 31, TYZOR LA, and TYZOR 1 Oi commercially
available from DuPont de Nemours & Co.
Emulsifiable, hydrolytically-stable, organotin catalysts are also useful for
this invention. Examples of such are mercaptoalcohol, mercaptide or sulfide
form of
diorganotin having a Sn-S or Sn=S bond. Further, illustrative examples are
R2Sn(SCOO) type compound, such as (n-C4H9)2Sn(SCH2C00); R2Sn(SS) type
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compound, such as (n-C8Ht~)2Sn(SCH2COOCH2CH2OCOCH2S); R2Sn(SCH2COOR)z
type compound, such as (n-C4H9)2Sn(SCH2COOC8H»-iso)2; RSn(SCH2COOR)3 type
compound, such as (n-C4H9)Sn(SCH2COOC8H»-iso)3; R2Sn=S compound, such as
(n-C8H»)2Sn=S or the like; and
R52Sn Z
W
where R5 = 1-8 carbon atoms alkyl or aryl; W = -S- or -O-; and Z = -
CH2CH(CH20H)-
or -CH2CH(OH)CH2-. Preferred examples are FOMREZ UL-1, UL-22, and UL-32 from
Witco and dibutyltin bis(1-thioglycerol).
The catalyst should be present at a level of at least 0.1 percent by
weight of the total composition. Less than 0.1 percent of the catalytic metal
usually
produces no significant effect on the reaction. Generally speaking, the
catalyst can be
used in an amount of 0.1 to 20 percent by weight, preferably 0.1 to 10 percent
by
weight, for cost considerations and color integrity of the polymer.
~II1) Water
Water should be present at 99.8 to 24.9 weight percent of the
composition. Water may be added to either (I) or (II) before combining
components (!)
and (II).
~IVZ Other Ingredients
The preferred pH range of the present aqueous compositions is about
5.5 to 8.5, with most preferred being 7Ø Thus, it is generally desirable
that the
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aqueous dispersion also contain a small amount of a buffer. Any conventional
buffering agent or mixtures of such agents known in the art can be employed,
such as
sodium acetate and sodium bicarbonate. The buffer should be present at about
1.0
parts by weight or less based on 100 parts by weight of polymer.
Furthermore, the comNositions of the present invention may include an
appropriate amount of thickeners {such as carboxymethylcellulose,
methylcellulose,
hydroxyethylceliulose, polyvinyl alcohol, polyacrylic acid), fillers,
pigments, dyes,
heat-stabilizing agents, preservatives, and penetrants (such as aqueous
ammonia)
and other common additives. In addition, commercially available water-based
polymer
dispersions can be blended with the water-dispersible compositions of the
present
invention, provided that they do not cause instability. Examples include
conventionally
known waterborne acrylics, cellulosics, aminopfasts, urethanes, polyesters,
alkyds,
epoxy systems, silicones or mixtures thereof.
Nonionic surfactants having a hydrophilic iipophilic balance (HLB) in a
range suitable to emulsify the catalyst and/or polymer may also be used
herein. The
optional ingredients may be added at any time, although in most cases, the
catalyst
should be added last.
METHOD OF MANUFACTURE
. The compositions of the present invention are prepared by adding the
catalysts to the si(ylated polymer dispersion or emulsion. The method employed
to
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mix these components is not critical and any commonly used low shear
equipment,
such as a blade or paddle mixer, is suitable.
USE/ADVANTAGE
The compositions do not seed or gel over an twelve month period of
room temperature storage. More preferably compositions have a shelf life of at
least
twenty-four months.
The compositions of the present invention are intended to be cured upon
use. They may be cured at a range of temperatures, including ambient cure or
elevated temperature cure. Such curing may be accomplished by standard means
in
the art.
It is possible to use the compositions for various purposes, e.g., paints,
adhesives, coating materials, binders and sealants, and take advantage of the
above
excellent characteristics of compositions of the present invention. The cured
compositions form a coating having excellent gloss, solvent resistance,
adhesion,
hardness, abrasion resistance and mar resistance. The compositions of this
invention
are film forming and are useful for forming protective and/or water repellent
coatings
on a variety of substrates, such as metal, wood, textiles, feather, and
ceramics. A
composition according to the present invention, depending on the presence of
pigments or other conventional components, may be used as a basecoat,
clearcoat,
print paste binder, sizing, coating or primer. Cured films having superior
transparency
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and solvent resistance may be formed with no surface defects. Washing
resistant
coatings may be created.
MEK double rub tests, gel content and NMP paint adhesion tests of the
latex films illustrate the enhanced siloxane crosslinking effected by the
catalysts used
in the present invention. Cured compositions made according to the present
invention
have an MEK rub resistance (performed according to ASTM D 4752-87) of at least
20
and preferably at least 40 after curing under mild conditions and for short
periods of
time. The cured compositions have improved adhesion performed according to the
NMP procedure described in Sabata, et al., Journal of Adhesion Science and
, TechnoloQV, 7(11), 1153-1170 (1993), of at least ten minutes and preferably
at least twenty minutes.
Examples
The following Examples are given to facilitate the understanding of this
invention without any intention of limiting the invention thereto. All parts
in these
Examples are by weight.
Exameles 1-18 and Comparative Examales I-VIII. Preparation of Silylated
Polymer
The preparation of a vinyl acrylic latex containing
3-methacryloxypropyltriisopropoxysilane, Silane A, as a co-monomer is
presented.
The mole ratio of vinyl acetatelbutyl acrylate/ silane monomers was
86.3/9.8/3.9,
respectively. The latex was produced by a semicontinuous batch process. 419.5
parts of deionized water, 26.5 parts of Igepal CA-897, 3 parts *Igepal CA 630,
2 parts
*Trade-mark 15
CA 02217725 2003-04-30
of sodium bicarbonate and 2.5 parts of *Natrosol 250 lv~R were charged into a
one
liter reactor equipped with an overhead condenser and a metal-bladed stirrer.
The
system was heated to 65°C with a heating mantle and purged with
nitrogen. Then, 1.8
parts of ammonium persuffate and 3.6 parts of *Alipal EP-11o were added. Ten
percent of the monomer mixture (prepared by pre-mixing 385 parts of vinyl
acetate, 65
parts of butylacrylate and 66 parts or 4 mole % of
3-methacryloxypropyltriisopropoxysilane was then added in less than 1 minute.
The
temperature was maintained below 75°C. After the addition, the reaction
was allowed
to continue for another 15 minutes. The stirring rate was kept constant at.150
rpm.
After the seed latex was made by this batch process, the remaining 90% of the
monomer mixture was added over a three hour period at a rate that permitted
the heat
of reaction to be removed and the reaction temperature maintained at
75°C. When
the monomer mixture had been completely added, the emulsion was held at
75°C for
30 minutes and 0.1 part of t-butyl hydroperoxide-70 was added. 25 parts of 2%
sodium formaldehyde sulfoxylate was added over a period of one hour while
maintaining the temperature at 75°C. After completion of the reaction,
the pH of the
reaction solution was adjusted to 7.5 by adding a 5% ammonia solution.
The procedure for the synthesis of a vinyl acrylic latex containing 3-
methacryloxypropyitriisopropoxysilane (A) was repeated using different sllane
monomers. These silane monomers were, 3'-methacryloxypropyltri-iso-
butoxysiiane
(B), 3-methacryloxypropyltrioctoxysilane (C), vinyltri-iso-butoxysilane (0),
and vinyltri-
ierr butoxysilane (E). The quantity of silane monomers used was varied. M
these
*Trade-mark
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examples, sitane concentrations ranging from 0.17 to 4 mole percent were
employed
using a homogeneous process (seeding polymers followed by starved monomers
' feeding), core-shell technology, or delayed-stlane monomer addition at the
last 10% of
polymerization. Solid contents were in the range of 44% to 56%. The particle
sizes
were in the range of 0.1 to 1 Vim. The amount of each monomer used to prepare
the
silylated polymers are given in Table I.
As a comparison, these procedures were repeated for synthesis of
emulsion polymers containing 3-methacrytoxypropyltrimethoxysilane (X),
vinyltriethoxysilane (Y) and no silane. The silylated polymers contained 4
mole percent
Silane X gelled during preparation.
The silylated polymer containing three weight percent of Sllane Y gave a
latex with a viscosity of 740 cp. When the concentration of Silane Y was
raised to 7.7
wt % of the polymers, the latex gave high viscosity (5800 cp.) and gelled
after 1 week
storage at ambient condition. The amounts of each monomer used to prepare the
polymers used as a comparative examples are set forth in Table ! below.
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TABLE I The weight and mole percent of monomers used to prepare silylated
- - polymer emulsions of present invention and comparative examples.
Example Vinv l AcetateButvl
Acrviate
No. Silane Weight Weioht Mole Weinht Mole
% Mole % % %
%
1 A 12.8 3.9 74.6 86.3 12.6 9.8
2 A 1.5 0.40 84.6 89.7 13.9 9.9
3 A 1.0 0.27 85.0 89.8 14.0 9.9
4 A 10.0 2.85 85.0 93.5 5.0 3.7
B 14.3 3.9 73.3 86.3 12.4 9.8
6 B 1.63 0.40 84.5 89.7 13.9 9.9
7 B 1.0 0.24 85.0 89.8 14.0 9.9
8 B 10.0 2.53 85.0 93.8 5.0 3.7
9 C 19.6 3.9 68.8 86.3 11.6 9.8
C 2.4 0.40 83.9 89.7 13.7 9.9
11 C 1.0 0.17 85.0 89.9 14.0 9.9
12 C 10.0 1.65 85.0 88.5 5.0 9.8
13 D 11.0 3.9 76.2 86.3 12.8 9.8
14 D 1.2 0.4 84.9 89.7 13.9 9.9
D 10.0 3.2 85.0 87.1 5.0 9.7
16 E 11.0 3.9 76.2 86.3 12.8 9.8
17 E 1.2 0.4 84.9 89.7 13.9 9.9
18 E 10.0 3.2 85.0 87. 5.0 9.7
l
Com parative Vinyl Butyl % Polymer
Acetate Acrylate
No. Silane Weight Mofe Weight Moie
% % % %
Weight in
% emulsion
Mois
%
l X 10.0 3.9 77.0 86.3 13.0 9.850.2
II X 1.1 0.4 85.0 89.7 13.9 9.950.2
111 X 1.0 0.37 85.0 89.7 14.0 9.950.0
IV X 10.0 3.5 85.0 86.8 5.0 9.750.0
V Y 7.9 3.9 78.8 86.3 13.3 9.850.2
V Y 0.84 0.4 85.2 89.7 14.0 9.950.2
I
VII Y 15.4 8.0 71.7 82.1 12.9 9.950.2
Vlllnone 0.0 0.0 85.0 90.0 15.0 10.0
50.0
Examples 19-31 - Shelf Stability of Compositions
The shelf life stabilities of the water borne polymers containing the
sterically
hindered alkoxy groups in the presence of the curing catalysts were determined
by
composition viscosity and 29Si NMR spectroscopy. The catalysts of the present
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invention were added to the silylated polymer emulsions of the present
invention that
were described in Table 1, and mixed for five minutes with a paddle. The types
and
amounts (weight percent) of catalysts that were added to the silylated polymer
emulsions are repeated in Tables II and III. The viscosities, reported in
centipoise
(cp), were determined for the compositions using a Brookfield viscometer, #3
spindle,
according to ASTM D 2196-86.
Examples 19-28, reported in Table 1l, experienced only a slight increase in
viscosity over a two month period. For example, silylated polymer emulsion
described
in Example 9 and in the presence of five weight percent TYZOR 131 catalyst
only
increased the viscosity from 960 to 1060 cp after storage at room temperature
for two
months. (Example 21 ). When silylated polymer emulsions were prepared using
high
levels of alkoxysilyl groups which are not stericafly hindered, the
compositions gelled
within short periods of time (i.e., one week) after preparation, even when
there were
no curing catalysts present (as shown in Comparative Examples XI - Xlll). The
emulsions of polymers containing sterically hindered afkoxysilyl groups are
stable in
the absence of a curing catalyst, as shown in Comparative Examples IX and X.
The stability of the emulsions of polymers containing sterically hindered
alkoxysilyl groups in the presence of the curing catalysts of the present
invention were
also determined using 29Si spectroscopy. This technique directly measures the
amount of cure that is occurring in the compositions by measuring the amounts
of silyl
ester groups [-Si(OR)3] that have and have not undergone any crosslinking or
curing
reaction. Examples 29-31, as indicated in Table I I I below, show that the
silyi ester
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group has not
undergone any
curing and therefore
makes up 100%
of the silicon
species present than 40 days at room temperature.
after storage When no
for greater
curing catalysts
were present,
the emulsions
of the prior
art were stable,
as indicated
in Comparative
Examples XIV-XVI.
Table Il Viscosity er in the absence and presence
of silylated of catalysts
polym
Emulsion
Example No. Example Catalvst,Weiaht0 mo. 2 mo. 3 mo. 6
%
mo.
19 1 TYZOR 131, 100 140 -- --
5
5 TYZOR 131, 200 280 -- --
5
21 9 TYZOR 131, 960 1060 -- --
5
22 13 TYZOR 131, 580 840 -- --
5
15 23 16 TYZOR 131, 1500 1700 -- --
5
24 2 TYZOR 131, 1660 1800 -- --
1
6 TYZOR 131, 1180 1100 -- --
1
26 10 TYZ OR 131, 760 1060 --
1
27 14 TYZOR 131, 1520 1800 -- --
1
20 28 ' 17 TYZOR 131, 1140 1340 -- --
1
IX 13 None , 0 1140 -- 1180 --
X 14 None, 0 2210 -- --
2020
XI I None, 0 gelled
25 Xll IV None, 0 gelled
Xllf VII None, 0 gelled
Table III - 29Si NMR analysis of silylated polymer emulsions and comparative
examples
' Emulsion Polymer Si(OR)3
from ,
Example No. Example Catalyst, % Time ydays)Mol
29 8 TYZOR 131, 5 41 100
30 12 TYZOR 131, 5 52 100
31 15 TYZOR 131, 5 47 100
Xi V 8 None 120 100
XV 12 None 210 100
XVI 15 None 120 100
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Polymer-Si(OR)3 represents the amount of silyl ester that has not reacted to
form
sifoxane bonds or crosslinks {Si-O-Si)
Examples 32-3fi - Gel Content of Cured Compositions
The effectiveness of the curing catalysts in promoting the crosslinking of the
polymer containing sterically hindered alkoxysilyl groups is demonstrated by
the gel
content of films. The gel content was determined by pouring compositions of
the
present invention or comparative examples into a petri dish and allowing them
to
cure at room temperature for either ten days or ten weeks. One gram of the
dried
(cured) film was removed and divided into small rectangular pieces which were
weighed (w~), placed into a celluiosic thimble and extracted with methyl ethyl
ketone
(MEK) solvent for twelve hours under nitrogen atmosphere using a Soxhfet
extractor.
After extraction, the sample remaining in the thimble was dried and the
remaining
sample was weighed (w2). The gel content was determined by the equation:
Gel content (%) _ [(Wi'w2)~w1]x1 OO, where wi and w2 are as above.
The data given in Table IV shows that the gel content of the polymers
containing
stericaily hindered alkoxysilyi groups was significantly higher when cured in
the
presence of the catalysts (Examples 32-35) than when cured in the absence of
catalyst (Comparative Examples XVII - XX). For example, the polymer described
in
Example 5 gave gel contents of 75.6 and 49.9 percent when cured in the
presence
of 5 percent TYZOR 131 and absence of catalyst, respectively. Even long curing
times, such as ten weeks at room temperature, did not yield the same high
level of
cure. The tent-butoxy silyl group of polymer 16 was so sterically hindered
that it did
not cure even in the presence of the curing catalyst. A comparative polymer
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containing no silane, such as a polymer described in Comparative Example Vill
did
not crosslink even when allowed to stand for ten weeks. The gel content of
dried
polymer VIII was zero percent.
Tabte IV Gel content of films cast from silylated polymer emulsions in the
presence and absence of curing catalysts.
Emulsion
Example No. Example No. Catalysts, % Gel Content,
32 1 TYZOR 131, 5 25.4'
33 5 TYZOR 131, 5 75.6'
34 9 TYZOR 131, 5 78.3'
35 13 TYZOR 131, 5 53.1'
36 16 TYZOR 131, 5 0'
XVII 1 None 13.12
XVIII 5 None 49.92
XIX 9 None 69.72
XX 13 None 23.82
XXI 16 None 0.92
' Cured at room temperature for 10 days
2 Cured at room temperature for 10 weeks
Examples 37 - 42 - Fiim Quaiity
The film quality or appearance is highly dependent upon the selection of the
curing catalysts. For example, the water soluble catalyst in Examples 37-38 or
emulsified catalyst of the present invention in examples 39-42, when used in
combination with the emulsions of polymers containing sterically hindered
alkoxysilyl
groups, gave cured films that were smooth and free of surtace defects as
indicated
in Figure 1 which shows Examples 37-42 as plates B-G, respectively, with plate
A
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indicating the plate without the presence of the catalyst. The types and
amounts of
the catalyst used are given in Table V.
The catalyst emulsions were prepared by emulsifying an organotin catalyst
with a compatible emulsifier so that a stable emulsion which is readily
dispersible in
aqueous systems is formed. Examples of catalyst emulsions are Elf Atochem PE-
10i 3, Witco FOMREZ UL-1, FOMREZ UL-22 and UL-32. To five grams each of the
liquid catalysts, 7.1 grams of IGEPAL CA-987 was added followed by an
additional
7.9 grams of double distilled water. The mixture was stirred vigorously for
about
thirty minutes. The PE-1013 resulted in a stable microemulsion. FOMREZ UL-1,
UL-22 and UL-32 formed emulsions which were stable.
Films were prepared by casting them using a draw down bar onto phosphated
stainless steel panels. The dry film thickness was 2 mils [50.8 ~,m]. The
films were
cured at 23°C and 50% relative humidity for seven days.
When catalysts which have been commonly used to cure solvent based or
neat polymers containing silyl groups, such as dialkyl tin carboxylates,
amines or
titanate esters, are employed in waterborne dispersion polymer systems the
cured
film contains many surface defects, as shown in Comparative Examples XXIII -
XXVII in Table V and Figure 2 where plates B-G correspond to Comparative
Examples XXI11-XXVII, respectively, with Plate A having no catalyst. These
examples and figures illustrate the importance of selecting the curing
catalyst from
' the groups described in the present invention to achieve films of uniform
cure and
free of defects.
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The utility of the compositions of the present invention is shown by the
improvement in solvent resistance and adhesion of cured compositions. The
solvent
resistance was determined in MEK double rubs, as described in ASTM D 4752-87.
The films were cured either by baking or drying. The baking conditions were
127 °C
for twenty minutes followed by seven days at 23°C and 50% relative
humidity. The
data given in Table Vl show that the amount of catalyst of the present
invention is
important to the solvent resistance of the cured film. Films of polymers
containing
sterically hindered alkoxysilyl groups and no catalysts gave MEK double rubs
of only
12 to 22, as shown in Comparative Examples XXXV - XXXVIII. If the polymer
contains no silyl groups, the solvent resistance is very poor, giving only 5
to 9 MEK
double rubs.
The films cast from emulsions of polymers containing sterically hindered
alkoxysilyl groups and catalysts of the present invention gave good solvent
resistance. Moreover, the solvent resistance is very good, provided that the
catalyst
concentration is not too low. For example, films cast from compositions of the
present invention where the concentration of the catalyst was 0.5 percent or
higher .
gave MEK double rubs of between 21 and 128, whether the films were cured by
either the bake or air-dried method as shown in Examples 45 to 50, and 53 to
86. At
low catalyst concentrations (such as 0.05 percent} the films lost some of
their
solvent resistance, as shown in Examples 43, 44, 51 and 52. Aging the
compositions of the present invention for extended shelf lives was not
deleterious to
the solvent resistance characteristics of cured films. For example,
compositions
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aged for periods of two to eight weeks before casting films gave solvent
resistance
that was equal to or better than films cast down from compositions freshly
made, as
shown in Examples 59 to 78.
Table V Coating film quality of silylated polymer emulsion cured in the
presence
of water soluble or dispersible catalyst of present invention and comparative
examples
Emulsion
Example No. Exam..~~le Catalyst, % Film Quality
No.
37 9 TYZOR 131, 5 Smooth film no defects
38 9 TYZOR LA, 5 Smooth film no defects
39 9 PE-1013, 1 Smooth film no detects
40 9 FOMREZ UL-1, 1 Smooth film no defects
41 9 FOMREZ UL-22, 1 Smooth film no defects
42 9 FOMREZ UL-32, 1 Smooth film no defects
XXII 9 Dibutyl maleate, White granular particles
1
XXIII 9 Dibutyl tin dilaurate,Craters in film
1
XXIV 9 Dibutyl tin diacetate,Large craters in
1 film
XXV 9 TYZOR GBA, 5 Crater and discolored
film
XXVI 9 4,4' (oxydi-2,1-ethanediyl)
Gel particles in
film
bis morpholine,
1
XXVII 9 None Smooth film, no effects
' Cured at 23 C and 50 nt relative humidity
perce for 7 days.
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_ _ Table The solvent
V! resistance
of cured
films
of silylated
polymer
as
determined rubs.
by methyl
ethyl
ketone
double
Example Polymer Age of Compos.MEK Dble
No. EmulsionCatalyst. % Cure B/f Cure (wks)Rubs
type
43 5 TYZOR 131, 0.05 Baked 0 11
44 5 TYZOR 131, 0.05 Dried 0 1 g
45 5 TYZOR 131, 0.5 Baked 0 31
46 5 TYZOR i 31, 0.5 Dried 0 47
47 5 TYZOR 131, 1.0 Baked 0 37
48 5 TYZOR 131, 1.0 Dried 0 47
49 5 TYZOR 131, 2.0 Baked 0 41
50 5 TYZOR 131, 2.0 Dried 0 50
51 5 TYZOR LA, 0.05 Baked 0 11
52 5 TYZOR LA, 0.05 Dried 0 15
53 5 TYZOR LA, 0.5 Baked 0 21
54 5 TYZOR LA, 0.5 Dried 0 30
55 5 TYZOR LA, 0.5 Baked 0 41
56 5 TYZOR LA, 1.0 Dried 0 33
57 5 TYZOR LA, 2.0 Baked 0 39
58 5 TYZOR LA, 2.0 Dried 0 43
59 1 TYZOR 131, 5 Baked 0 38
60 1 TYZOR 131, 5 Baked 2 80
61 i TYZOR 131, 5 Baked 4 1 i 9
62 1 TYZOR 131, 5 Baked 8 99
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_ _ _ ExamplePolymer Age of Compos.MEK Dble
No. Emulsion Catalyst, % Cure B/f Cure lwks~Rubs
type
63 5 TYZOR 131, 5 Baked 0 50
64 5 TYZOR 131, 5 Baked 2 97
65 5 TYZOR 131, 5 Baked 4 g7
66 5 TYZOR 131, 5 Baked 8 125
67 9 TYZOR 131, 5 Baked 0 50
68 9 TYZOR 131, 5 Baked 2 81
69 9 TYZOR 131, 5 Baked 4 103
70 9 TYZOR 131, 5 Baked 8 128
71 13 TYZOR 131, 5 Baked 0 38
72 13 TYZOR 131, 5 Baked 2 74
73 13 TYZOR 131, 5 Baked 4 100
74 13 TYZOR 131, 5 Baked 8 97
75 16 TYZOR 131, 5 Baked 0 29
76 16 TYZOR 131, 5 Baked 2 47
77 16 TYZOR 131, 5 Baked 4 25
78 16 TYZOR 131, 5 Baked 8 67
79 9 FOMREZ-UL-1, Baked 0 51
1
80 9 FOMREZ UL-1, Dried 0 39
1
81 9 FOMREZ UL-22, Baked 0 53
1
82 9 FOMREZ UL-22, Dried 0 48
1
83 9 FOMREZ UL-32, Baked 0 49
1
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- _ - ExamplePolymer Age of Compos.MEK Dble
No. Emulsion Catalyst. Cure B/f Cure~
% type k
l
w Rubs
s
84 9 FOMREZ UL-32, Dried 0 41
1
85 9 PE-1013, Baked 0 30
1
86 9 PE-1013, 1 Dried 0 22
XXVIII VII None, 0 Baked 0 5
XXIX VII None, 0 Dried 0 g
XXX Vlii TYZOR 131, 2 Baked 0 7
XXXI VI I I TYZOR 131, 2 Dried 0 7
XXXII VIII TYZOR LA, 2 Baked 0 7
XXXItI Vlll TYZOR LA, 2 Dried 0 g
XXXiV 1 None Baked 0 22
XXXV 5 None Baked 0 27
XXXVI 9 None Baked 0 19
XXXVtI 16 None Baked 0 12
XXXVIit 2 None Baked 0 8
XXXIX 6 None Baked 0 i 7
XL 10 None Baked 0 14
XLI 14 None Baked 0 14
XLtI 17 None Baked 0 7
XLIII VI None Baked 0 g1
XLIV 5 None Baked 0 7
XLV 5 None Dried 0 7
Examples 87-91 - Adhesion Characteristics
The adhesion of the cured films improved as the concentration of the catalyst
of the present invention was increased, as shown in Table VII. The adhesion of
the
cured films of the composition of the present invention was determined by the
NMP
paint adhesion test, as described above. As the amount of TYZOR LA catalyst
was
increased from 0.05 to 2.0 weight percent, the NMP adhesion improved from 5.6
to
56 minutes, respectively, as shown in Examples 88-91.
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Table Vll - Data
on paint adhesion
of films
Silylated Polymer
Example No. Example No. Catalyst, % NMP Paint Adhesion
mins.
87 7 TYZOR 131,0.05 5,5
88 7 TYZOR LA, 0.05 5.6
89 7 TYZOR LA, 0.5 1 g
90 7 TYZOR LA, 1.0 3g
91 7 TYZOR LA, 2.0 56
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