Liquid emulsion polymers useful as pH responsive thickeners for aqueous systems

Novel aqueous liquid emulsion polymers are prepared by the copolymerization of (A) about 15-60 weight percent of a C.sub.3 -C.sub.8 .alpha.,.beta.-ethylenically unsaturated carboxylic acid monomer, preferably acrylic or methacrylic acid or a mixture thereof with itaconic or fumaric acid, (B) about 15-80 weight percent of a nonionic copolymerizable C.sub.2 -C.sub.12 .alpha.,.beta.-ethylenically unsaturated monomer, preferably a monovinyl ester such as ethyl acrylate or a mixture thereof with styrene, acrylonitrile, vinyl chloride or vinyl acetate, and (C) about 1-30 weight percent of certain nonionic vinyl surfactant esters, such as nonylphenoxypoly(ethyleneoxy).sub.9 ethyl acrylate, to give an emulsion copolymer stable as an aqueous colloidal dispersion at an acid pH lower than about 5.0 but responsive to pH adjustment with base. These emulsion polymers adjusted to a pH of about 5.5 or higher are effective thickeners for a wide variety of aqueous systems including cosmetic products, drilling muds, and particularly aqueous coating compositions such as latex paint.

BACKGROUND OF THE INVENTION 
Polymeric water-soluble thickening agents are widely known and used in many 
aqueous systems including latex paints and other aqueous coating 
compositions. 
The widespread use of latex paints, i.e., paints based on aqueous 
dispersions of synthetic organic polymers, has prompted continued research 
on product and process improvements. One particularly important concern is 
controlling the paint rheology to obtain proper flow and leveling with a 
minimum of dripping and spattering. Cellulose ethers, such as described in 
Glomski et al. U.S. Pat. No. 3,769,247, are often effectively used as 
thickeners for latex paints. However solid, water-soluble polymers derived 
from cellulose and other natural products are becoming increasingly 
expensive to produce because of high capital, energy, and waste control 
costs. 
Alkali soluble latex copolymers have been known for some time. Thus, Hager 
and Martin U.S. Pat. Nos. 3,003,987 and 3,070,561 and Miller U.S. Pat. No. 
3,081,198 describe copolymers of acrylic and methacrylic acids and esters 
which may be thickened by replacing a portion of the hydrogen ions of the 
copolymer carboxyl groups with ammonium or alkali metal ions. Other types 
of polymeric thickeners are disclosed by Junas and LaTorre U.S. Pat. Nos. 
3,652,497 and 3,708,445, Zimmerman U.S. Pat. No. 3,657,175, Chang and 
McDowell U.S. Pat. No. 3,891,591, and Gibson U.S. Pat. No. 4,003,870. All 
contain various carboxylic acid groups which can be solubilized in water 
by neutralization with a water-soluble base. However, to date this 
technology has had limited impact on major markets for water-soluble 
polymeric thickeners. 
More recently, Evani and Corson developed, as described in U.S. Pat. No. 
4,008,202 and related patents, a solid styrene-maleic 
anhydride-vinylbenzyl ether terpolymer soluble at high pH and useful as a 
thickener for aqueous solutions. In spite of excellent rheology, stability 
problems and cost have limited its use as a paint thickener. Further 
improvements in this technology are clearly desirable. 
SUMMARY OF THE INVENTION 
New aqueous emulsion polymers have been discovered which provide stable 
liquid emulsions having low viscosity and relatively high solids content 
under acidic conditions, but which become very efficient polymeric 
thickeners for many aqueous systems when treated with base. These new 
products are preferably prepared in the form of an aqueous colloidal 
dispersion of water-insoluble polymer by emulsion polymerization at a pH 
of about 2.5 to 5.0 of three essential ethylenically unsaturated monomeric 
components: (A) a carboxylic acid monomer, (B) a nonionic vinyl monomer 
and (C) a nonionic vinyl surfactant ester. 
More specifically, a polymer useful as a pH responsive thickener for 
aqueous systems has been developed comprising an aqueous emulsion 
copolymer of: 
A. about 15-60 weight percent based on total monomers of at least one 
C.sub.3 -C.sub.8 .alpha.,.beta.-ethylenically unsaturated carboxylic acid 
monomer of the formula: 
##STR1## 
where R is H and R' is H, C.sub.1 -C.sub.4 alkyl, or --CH.sub.2 COOX; 
R is --COOX and R' is H or --CH.sub.2 COOX; or 
R is CH.sub.3 and R' is H; and 
X is H or C.sub.1 -C.sub.4 alkyl; 
B. about 15-80 weight percent of at least one nonionic, copolymerizable 
C.sub.2 -C.sub.12 .alpha.,.beta.-ethylenically unsaturated monomer of the 
formula: 
EQU CH.sub.2 .dbd.CYZ (II) 
where 
Y is H and Z is --COOR, --C.sub.6 H.sub.4 R', CN, Cl, 
##STR2## 
or --CH.dbd.CH.sub.2 ; Y is CH.sub.3 and Z is --COOR, --C.sub.6 H.sub.4 
R', CN or --CH.dbd.CH.sub.2 ; or 
Y and Z are Cl; and 
R is C.sub.1 -C.sub.8 alkyl or C.sub.2 -C.sub.8 hydroxyalkyl; 
R' is H, Cl, Br, or C.sub.1 -C.sub.4 alkyl; and 
R" is C.sub.1 -C.sub.8 alkyl; and 
C. about 1-30 weight percent based on total monomers of at least one 
nonionic vinyl surfactant ester of the formula: 
##STR3## 
where R is H or CH.sub.3, each R' is C.sub.1 -C.sub.2 alkyl, 
R" is C.sub.8 -C.sub.20 alkyl or C.sub.8 -C.sub.16 alkylphenyl, 
n is an average number from about 6-100 and m is an average number from 
about 0-50 provided that n.gtoreq.m and .SIGMA.(n+m) is about 6-100; said 
polymer being stable as an aqueous colloidal dispersion at a pH lower than 
about 5.0 but becoming an effective thickener for aqueous systems upon 
adjustment to a pH of about 5.5-10.5 or higher. 
The emulsion polymerization is normally carried out under acidic conditions 
in which the carboxylic acid groups are in protonated form to insolubilize 
the polymer and give a liquid emulsion. When the polymeric thickener is 
added as such a liquid colloidal dispersion, the finely divided polymer 
particles dissolve almost instantly upon pH adjustment. The ease of 
handling, metering, and dispersing the liquid emulsion polymer, the rapid 
solubilization by controlled pH adjustment, and the highly desirable 
rheological properties make this liquid emulsion polymer a most effective 
and efficient thickening agent for a wide variety of applications 
including latex paints and other aqueous coating compositions. 
DETAILED DESCRIPTION OF THE INVENTION 
1. Essential Monomeric Components 
The novel liquid emulsion polymers of this invention require three 
essential components: (A) about 15-60 weight percent of a C.sub.3 -C.sub.8 
.alpha.,.beta.-ethylenically unsaturated carboxylic acid monomer, (B) 
about 15-80 weight percent of a copolymerizable nonionic vinyl monomer, 
and (C) about 1-30 weight percent of certain nonionic vinyl surfactant 
esters. It has been discovered that the effectiveness of these liquid 
emulsion polymers as a pH responsive thickener for many aqueous products 
is critically dependent on these components. The acid component A provides 
the requisite pH responsiveness; the nonionic vinyl comonomer B provides 
an extended polymer backbone and added hydrophiliclipophilic balance; and 
the nonionic vinyl surfactant ester C provides an in situ, bound 
surfactant to control the rheology of the aqueous system containing the 
solubilized polymeric thickener. Within the stated limits, the proportions 
of the individual monomers can be varied to achieve optimum properties for 
specific applications. 
A. Carboxylic Acid Monomer 
The liquid emulsion polymer requires about 15-60 weight percent based on 
total monomers of a C.sub.3 -C.sub.8 .alpha.,.beta.-ethylenically 
unsaturated carboxylic acid monomer of the formula: 
##STR4## 
where R is H and R' is H, C.sub.1 -C.sub.4 alkyl, or --CH.sub.2 COOX; R is 
--COOX and R' is H or --CH.sub.2 COOX; or R is CH.sub.3 and R' is H; and X 
is H or C.sub.1 -C.sub.4 alkyl. 
Acrylic or methacrylic acid or a mixture thereof with itaconic or fumaric 
acid are preferred, but crotonic and aconitic acid and half esters of 
these and other polycarboxylic acids such as maleic acid with C.sub.1 
-C.sub.4 alkanols are also suitable, particularly if used in minor amount 
in combination with acrylic or methacrylic acid. For most purposes, it is 
preferable to have at least about 25 weight percent and most preferably 
from about 35-55 weight percent of the carboxylic acid monomer. However, 
polycarboxylic acid monomers and half esters can be substituted for a 
portion of the acrylic or methacrylic acid, e.g., about 1-15 weight 
percent based on total monomers. 
B. Nonionic Vinyl Monomer 
To provide the extended polymer backbone and body needed for effective 
thickening requires about 15-80 weight percent of at least one 
copolymerizable nonionic C.sub.2 -C.sub.12 .alpha.,.beta.-ethylenically 
unsaturated monomer selected from the group consisting of the formula: 
EQU CH.sub.2 .dbd.CYZ (II) 
where 
Y is H and Z is --COOR, --C.sub.6 H.sub.4 R', CN, Cl, 
##STR5## 
or --CH.dbd.CH.sub.2 ; Y is CH.sub.3 and Z is --COOR, --C.sub.6 H.sub.4 
R', CN or --CH.dbd.CH.sub.2 ; or 
Y and Z are Cl; and 
R is C.sub.1 -C.sub.8 alkyl or C.sub.2 -C.sub.8 hydroxyalkyl; 
R' is H, Cl, Br, or C.sub.1 -C.sub.4 alkyl; 
R" is C.sub.1 -C.sub.8 alkyl. 
Typical of such monomers are the C.sub.1 -C.sub.8 alkyl and C.sub.2 
-C.sub.8 hydroxyalkyl esters of acrylic and methacrylic acid including 
ethyl acrylate, ethyl methacrylate, methyl methacrylate, 2-ethylhexyl 
acrylate, butyl acrylate, butyl methacrylate, 2-hydroxyethyl acrylate, 
2-hydroxybutyl methacrylate; styrene, vinyltoluene, t-butylstyrene, 
isopropylstyrene, and p-chlorostyrene; vinyl acetate, vinyl butyrate, 
vinyl caprolate; acrylonitrile, methacrylonitrile, butadiene, isoprene, 
vinyl chloride, vinylidene chloride, and the like. In practice, a 
monovinyl ester such as ethyl acrylate or a mixture thereof with styrene, 
hydroxyethyl acrylate, acrylonitrile, vinyl chloride or vinyl acetate is 
preferred. 
These monomers, of course, must be copolymerizable with the carboxylic acid 
and vinyl surfactant ester comonomers. Normally about 15-80 weight 
percent, and preferably about 20-60 weight percent of nonionic vinyl 
monomer, based on total weight of monomers, is used in preparing the 
liquid emulsion polymer. 
C. Nonionic Vinyl Surfactant Ester 
The third required monomer component is about 1-30 weight percent based on 
total monomers of a nonionic vinyl surfactant ester of the formula: 
##STR6## 
where R is H or CH.sub.3 ; each R' is C.sub.1 -C.sub.2 alkyl; R" is 
C.sub.8 -C.sub.20 alkyl or C.sub.8 -C.sub.16 alkylphenyl; n is an average 
number from about 6-100 and m is an average number from about 0-50 
provided that n.gtoreq.m and .SIGMA.(n+m) is about 6-100. 
Preferred are the acrylate and methacrylate surfactant esters selected from 
the group consisting of: 
(1) alkylphenoxypoly(ethyleneoxy)ethyl acrylates of the formula: 
##STR7## 
where R is H or CH.sub.3 ; Y' is C.sub.8 -C.sub.16 alkyl, and n is about 
6-100; 
(2) alkoxypoly(ethyleneoxy)ethyl acrylates of the formula: 
##STR8## 
where R is H or CH.sub.3, R" is C.sub.8 -C.sub.20 alkyl, and n is about 
6-50; and 
(3) alkoxypoly(alkyleneoxy)ethyl acrylates of the formula: 
##STR9## 
where R is H or CH.sub.3, each R' is C.sub.1 -C.sub.2 alkyl, R" is 
C.sub.8 -C.sub.20 alkyl, and n is about 6-50 and m is about 1-40. 
These essential vinyl surfactant esters are the acrylic or methacrylic acid 
esters of certain nonionic surfactant alcohols. Such surfactant esters are 
known in the art. For example, Junas et al. U.S. Pat. No. 3,652,497 
describe the use of alkylphenoxyethyleneoxyethyl acrylates in preparing 
several other polymeric surfactant thickeners. Dickstein U.S. Pat. No. 
4,075,411 describes several processes for preparing such vinyl surfactant 
esters including the acid catalyzed condensation of commercially available 
nonionic polyoxyalkylene surfactant alcohols such as 
alkylphenoxypoly(ethyleneoxy)ethyl alcohol and block-polymeric glycols 
with acrylic, methacrylic, crotonic, maleic, fumaric, itaconic or aconitic 
acid. Alternate esterification methods including alcoholysis and 
transesterification are also described. Other suitable vinyl surfactant 
esters can be prepared from monoethers of mixed or heteric 
ethyleneoxypropyleneoxy-butyleneoxy polyglycols such as described in 
Patton U.S. Pat. No. 2,786,080. Additional surfactant alcohols which can 
be esterified for use herein are given in "McCutcheon's Detergents and 
Emulsifiers" 1973, North American Edition, Allured Publishing Corp., 
Ridgewood, N.J. 07450. 
Certain of these vinyl surfactant esters, i.e., those defined by Formula 
III and particularly the alkylphenoxy and alkoxyethyl esters of Formulas 
IV-VI, are useful in preparing the novel emulsion polymers described 
herein. It is essential that the surfactant be incorporated in the liquid 
emulsion product by copolymerization. Advantageously the requisite 
surfactant esters are prepared by the direct acid catalyzed esterification 
of the appropriate surfactant alcohol with an excess of the carboxylic 
acid monomer used as Component A. The resulting mixture with excess acid 
can be used directly in the copolymerization provided that at least 30 
percent, and preferably 50-70 percent or more, of the surfactant alcohol 
in the mixture is esterified. The vinyl surfactant ester can also be 
recovered, purified by conventional means using an appropriate inhibitor 
such as hydroquinone or p-tert-butylcatechol to prevent undesired 
homopolymerization, and then used to prepare the liquid emulsion polymers. 
It has been found that the hydrophiliclipophilic balance (HLB) of the vinyl 
surfactant ester is an important factor in the performance of the 
resulting emulsion polymer. Thus for a given polyethyleneoxy content, 
increasing the chain length of the terminal hydrophobic alkoxy or 
alkylphenoxy group will increase the efficiency of the resulting polymer 
as a thickener. Also for a given lipophilic group decreasing the number of 
polyethyleneoxy groups increases thickener efficiency. For many surfactant 
esters usable herein an average of about 10-40 ethyleneoxy groups (e.g., 
Formula III, n=10-40) is preferred. 
Also it has been found that the hydrophilic balance of the copolymer 
product can be adjusted to a degree by the judicious selection of the 
nonionic vinyl monomer B; e.g., a soft, (lower 
alkyl)poly(ethyleneoxy)ethyl ester of Formula VI can be used in a system 
with mixture of ethyl acrylate and a hard comonomer such as styrene. 
However, it is critical to the performance of these products that they 
contain an effective amount of an in situ, bound surfactant to control the 
rheology of the aqueous system thickened with the solubilized emulsion 
polymer. 
2. Copolymerization 
A. The novel liquid emulsion copolymers are conveniently prepared from the 
above-described monomers by conventional emulsion polymerization at an 
acid pH lower than about 5.0 using free-radical producing initiators, 
usually in an amount from 0.01 percent to 3 percent based on the weight of 
the monomers. The free-radical producing initiators conveniently are 
peroxygen compounds especially inorganic persulfate compounds such as 
ammonium persulfate, potassium persulfate, sodium persulfate; peroxides 
such as hydrogen peroxide; organic hydroperoxides, for example, cumene 
hydroperoxide, t-butyl hydroperoxide; organic peroxides, for example, 
benzoyl peroxide, acetyl peroxide, lauroyl peroxide, peracetic acid, and 
perbenzoic acid (sometimes activated by a water-soluble reducing agent 
such as ferrous compound or sodium bisulfite); as well as other 
free-radical producing materials such as 2,2'-azobisisobutyronitrile. 
Optionally, a chain transfer agent and an additional emulsifier can be 
used. Representative chain transfer agents are carbon tetrachloride, 
bromoform, bromotrichloromethane, long chain alkyl mercaptans and 
thioesters such as n-dodecyl mercaptan, t-dodecyl mercaptan, octyl 
mercaptan, tetradecyl mercaptan, hexadecyl mercaptan, butyl thioglycolate, 
isooctyl thioglycolate, and dodecyl thioglycolate. The chain transfer 
agents are used in amounts up to about 10 parts per 100 parts of 
polymerizable monomers. 
Often at least one anionic emulsifier is included in the polymerization 
charge and one or more of the known nonionic emulsifiers may also be 
present. Examples of anionic emulsifiers are the alkali metal alkyl aryl 
sulfonates, the alkali metal alkyl sulfates and the sulfonated alkyl 
esters. Specific examples of these well-known emulsifiers are sodium 
dodecylbenzenesulfonate, sodium disecondary-butylnaphthalene sulfonate, 
sodium lauryl sulfate, disodium dodecyldiphenyl ether disulfonate, 
disodium n-octadecylsulfosuccinamate and sodium dioctylsulfosuccinate. 
Optionally, other ingredients well known in the emulsion polymerization art 
may be included such as chelating agents, buffering agents, inorganic 
salts and pH adjusting agents. 
Polymerization at an acid pH lower than about 5.0 permits direct 
preparation of an aqueous colloidal dispersion with relatively high solids 
content without problems of undue viscosity. 
Usually the copolymerization is carried out at a temperature between about 
60.degree. C. and 90.degree. C. but higher or lower temperatures may be 
used. The polymerization is carried out batchwise, stepwise or 
continuously with batch and/or continuous addition of the monomers in a 
conventional manner. 
B. The essential monomers can be copolymerized in such proportions, and the 
resulting emulsion polymers can be physically blended, to give products 
with the desired balance of properties for specific applications. For 
example, if a more viscous product is desired, the acid and surfactant 
monomer content can be increased. Greater flexibility and coalescence can 
be obtained with higher amounts of ethyl acrylate. Addition of styrene as 
a second nonionic vinyl monomer will increase to a higher pH the 
adjustment required to dissolve the emulsion in an aqueous coating 
composition. Minor quantities of a polyfunctional monomer, such as 
itaconic or fumaric acid or isoprene to introduce a higher carboxylic acid 
content or limited crosslinking, provides further control on the 
solubility of the emulsion polymer after pH adjustment. Thus, by varying 
the monomers and their proportions, emulsion polymers having optimum 
properties for particular applications can be designed. 
In practice it is normally desirable to copolymerize about 15-60 weight 
percent based on total monomers (more desirably from about 25-60 weight 
percent, preferably about 35-55 percent, and most preferably about 40-50 
percent) of the carboxylic acid monomer A, about 15-80 weight percent 
(preferably about 20-60 percent, and most preferably about 35-50 percent), 
of the nonionic vinyl monomer B and about 1-30 weight percent (preferably 
about 2-20 percent, and most preferably about 2-12 percent) of the 
nonionic vinyl surfactant ester C. Particularly effective liquid emulsion 
polymer thickeners are obtained by copolymerization of about 40-50 weight 
percent of methacrylic acid, about 35-50 weight percent of ethyl acrylate, 
and about 2-12 weight percent of the methacrylic ester of a C.sub.9 
-alkylphenoxy(ethyleneoxy).sub.9 ethyl alcohol. 
3. Copolymer Properties 
The copolymer products prepared by emulsion polymerization at an acid pH 
are in the form of stable aqueous colloidal dispersions usually with a 
typical milky latex appearance. Such a liquid emulsion contains the 
copolymer dispersed as discrete particles having average particle 
diameters of about 500-3000 A, preferably about 1000-1750 A, as measured 
by light refraction. Dispersions containing polymer particles smaller than 
about 500 A are difficult to stabilize while particles larger than about 
3000 A reduce the ease of dispersion in the aqueous products to be 
thickened. 
These emulsion copolymers will normally have number average molecular 
weights of at least about 30,000 as determined by gel permeation 
chromatography. To provide most effective thickening with copolymers which 
are water-soluble when neutralized, molecular weights within the range of 
about 200,000 to 5,000,000 are preferred. In terms of a standard 
Brookfield viscosity measured as a 1 percent aqueous solution in ammonium 
salt form at pH 9 and 25.degree. C., a copolymer with a viscosity of about 
50-50,000 cps, and preferably about 100-30,000 cps, is particularly 
desirable for many applications. 
In the form of a stable, aqueous colloidal dispersion at an acid pH of 
about 2.5-5.0 the copolymer is particularly useful. Such aqueous 
dispersion may contain about 10-50 weight percent of polymer solids yet be 
of relatively low viscosity. Thus it is readily metered and blended with 
aqueous product systems. However, the dispersion is pH responsive. When 
the pH of the polymer dispersion is adjusted by addition of a base such as 
ammonia, an amine or a non-volatile inorganic base such as sodium 
hydroxide, potassium carbonate or the like, the aqueous mixture becomes 
translucent or transparent as the polymer dissolves at least partially in 
the aqueous phase with a concurrent increase in viscosity. This 
neutralization can occur in situ when the liquid emulsion polymer is 
blended with an aqueous solution containing a suitable base. Or if desired 
for a given application, pH adjustment by partial or complete 
neutralization can be carried out before or after blending the liquid 
emulsion polymer with an aqueous product. 
The term "liquid emulsion polymer" as applied to the new thickener of this 
specification means that the thickener is an emulsion polymer because the 
polymer was prepared by emulsion polymerization even though the polymer 
per se may be (and generally is) a solid at room temperature but is a 
"liquid" emulsion polymer because it is in the form of a liquid solution 
or dispersion. 
The pH viscosity response curves for several typical liquid emulsion 
polymers prepared by copolymerizing methacrylic acid (MAA), ethyl acrylate 
(EA), and nonylphenoxypoly(ethyleneoxy).sub.9 ethyl methacrylate (VSE-1A) 
are shown in the FIGURE as determined in aqueous media at a concentration 
of 1 percent by weight and at room temperature. Note that the pH range of 
initial viscosity build can be controlled by variation in the composition 
of the emulsion copolymer. 
These emulsion polymers are useful as water-soluble thickeners for a wide 
variety of applications ranging from cosmetics to drilling muds, but 
particularly for aqueous coating compositions. 
4. Use as A Thickener 
The liquid emulsion polymers described herein are particularly useful as 
thickeners for a wide variety of water-based compositions including 
aqueous brine and polymer solutions as well as aqueous slurries and 
colloidal dispersions of water-insoluble inorganic and organic material 
including compositions such as natural rubber, synthetic or artificial 
latexes and aqueous products containing such materials. 
Synthetic latexes which may be thickened with the liquid emulsion polymers 
are aqueous colloidal dispersions of water-insoluble polymers prepared by 
emulsion polymerization of one or more ethylenically unsaturated monomers. 
Typical of such synthetic latexes are emulsion copolymers of 
monoethylenically unsaturated compounds such as styrene, methyl 
methacrylate, acrylonitrile with a conjugated diolefin such as butadiene 
or isoprene; copolymers of styrene, acrylic and methacrylic esters, 
copolymers of vinyl halide, vinylidene halide, vinyl acetate and the like. 
Many other ethylenically unsaturated monomers or mixtures thereof can be 
emulsion polymerized to form synthetic latexes. Representative monomers 
are vinyl aromatic monomers such as styrene, .alpha.-methylstyrene, 
t-butylstyrene, chlorostyrene, vinyltoluene; conjugated dienes such as 
butadiene, isoprene, and 2-chloro-1,3-butadiene; vinyl chloride, 
vinylidene chloride, acrylonitrile, and methacrylonitrile; acrylic and 
.beta.-hydroxyalkyl acrylic esters; vinyl acetate, vinyl propionate, 
ethylene and methyl isopropenyl ketone. Also limited amounts of 
unsaturated carboxylic acid monomers such as defined by Formula I are 
frequently used in preparing the base polymer for latex paints. 
The artificial latexes are latexes which are produced by the dispersion or 
redispersion of pre-formed water-insoluble polymers or solutions thereof. 
The artificial latexes are produced by known emulsification processes, 
e.g., by addition of water with stirring until phase inversion occurs, by 
high shear mixing with water at elevated temperatures or by dilution of a 
mixture of water and a water-miscible solvent followed by stripping to 
remove the solvent. A surfactant is required in the emulsification process 
unless hydrophilic groups are attached to the polymer in sufficient 
quantity to assist dispersion but in insufficient quantity to produce 
water-solubility. 
Such artificial latexes are produced from polymers which are not prepared 
readily from monomers by emulsion polymerization, either because no 
substantial polymerization at a commercially acceptable rate is obtained 
under usual emulsion polymerization conditions, such as with isobutene, or 
because a particular form of the polymerized monomer is desired, for 
example, stereospecific polyisoprene, stereospecific polybutadiene and the 
like. Representative pre-formed polymers are polymers and copolymers of 
the mono-olefins having from 2 to 20 carbon atoms such as ethylene, 
propylene, 1-butene, 2-butene, isobutene, pentene, hexene, octene, 
dodecene, hexadecene, octadecene and especially those mono-olefins having 
up to 8 carbon atoms. Especially common types are the various 
ethylene/propylene copolymers. 
Illustrative of still other polymers which can be converted to artificial 
latexes are alkyd resins, block and graft copolymers; e.g., 
styrene/butadiene graft and block copolymers; epoxy resins such as the 
reaction products of epichlorohydrin and bisphenol-A; and thermosettable 
vinyl ester resins; e.g., the reaction products of approximately 
equivalent amounts of a polyepoxide and an unsaturated monocarboxylic acid 
such as acrylic acid and methacrylic acid or unsaturated fatty acids such 
as oleic acid. 
The thickeners of this invention are advantageous for use with the 
water-based compositions according to the foregoing description and with 
compositions containing those materials, especially coating compositions 
of various types. Mixtures of two or more thickeners may be used, if 
desired. Of course the latex polymers used in coating compositions are 
preferably film-forming at temperatures below about 25.degree. C., either 
inherently or through the use of plasticizers. Such coating compositions 
include water-based consumer and industrial paints; sizing, adhesives and 
other coatings for paper, paperboard, textiles; and the like. 
Usually these latex coating compositions contain added pigments, fillers 
and extenders such as titanium dioxide, barium sulfate, calcium carbonate, 
clays, mica, talc, silica and the like. The novel liquid emulsion polymers 
described herein are compatible with most latex paint systems and provide 
highly effective and efficient thickening. Suitable results are obtained 
using about 0.05-5.0 weight percent of the liquid emulsion polymer based 
on total weight of solids, and preferably about 0.1-2.0 weight percent. 
The aqueous compositions thickened with the liquid emulsion polymers of 
this invention preferably are those in which any dispersing or solvating 
liquid present consists of greater than 50 percent by weight of water.

The following examples illustrate further the present invention. Unless 
otherwise indicated, all parts and percentages are by weight. 
EXAMPLE 1 
Preparation of Vinyl Surfactant Esters 
The following are typical procedures for the preparation of the vinyl 
surfactant ester (VSE). 
A. Nonylphenoxypoly(ethyleneoxy).sub.9 ethyl Methacrylate A stainless steel 
reactor was charged with 474 parts (0.68 mole) of 
nonylphenoxypoly(ethyleneoxy).sub.9 ethanol (Igepal.RTM. CO-660 from GAF), 
0.31 part of hydroquinone and 0.16 part of Ionol.RTM. 
(2,6-di-t-butyl-p-cresol from Shell Chemical Co.). Then 8.6 parts of 
90.+-.2 percent H.sub.2 SO.sub.4 was added with stirring followed by 526 
parts (6.1 moles) of methacrylic acid stabilized with monomethyl ether of 
hydroquinone (MEHQ). With a slow stream of air bubbling through the 
reactant mixture, the reactor was heated at 105.degree. C. for two hours, 
cooled and then liquid product (VSE-1A) recovered. By liquid 
chromatographic analysis the neat product contained 47.2 weight percent 
surfactant ester (90 percent conversion), 4.8 weight percent unreacted 
surfactant, 46.8 weight percent excess methacrylic acid and 1.2 weight 
percent water, sulfuric acid and stabilizers. 
The vinyl surfactant ester can be used neat for the preparation of the 
desired emulsion copolymers or the ester can be recovered by conventional 
means. For use in neat form, a conversion to vinyl ester of at least 30-40 
percent is desirable to avoid too high free surfactant level in the 
subsequent emulsion polymerization. With a 4-10 fold excess of carboxylic 
acid monomer, 70-90 percent conversion can normally be obtained at 
100.degree.-120.degree. C. in 2-4 hours. 
Other strong acid catalysts including p-toluenesulfonic acid and strong 
acid cation exchange resins such as Dowex.RTM. 50 (H.sup.+ form) can be 
used, but 90 percent H.sub.2 SO.sub.4 is effective and convenient. Indeed, 
this general H.sub.2 SO.sub.4 catalyzed process has been used with a wide 
variety of C.sub.8 -C.sub.16 alkylphenoxypoly(ethyleneoxy)ethanols. 
B. Nonylphenoxypoly(ethyleneoxy).sub.39 ethyl Methacrylate 
A mixture of 222 parts of nonylphenoxypoly(ethyleneoxy).sub.39 ethanol, 384 
parts of methacrylic acid, 0.06 part of hydroquinone and 0.08 part of 
Ionol.RTM. was blended in a stirred glass reactor and 5.5 parts of 
concentrated H.sub.2 SO.sub.4 was added as esterification catalyst. The 
mixture was slowly heated to 110.degree. C., held at 110.degree. C. for an 
additional 145 minutes and then cooled to give 611 parts of a neat ester 
(VSE-1B) containing 38 weight percent of the surfactant ester and 62 
weight percent of unreacted methacrylic acid. 
C. Dodecylphenoxypoly(ethyleneoxy).sub.10 ethyl Methacrylate 
A mixture of 74.4 parts (0.1 mole) of 
dodecylphenoxypoly(ethyleneoxy).sub.10 ethanol (T-Det DD-11 from Hayworth 
Chemical Co.), 129 parts (1.5 moles) of methacrylic acid and 0.06 part 
each of hydroquinone and Ionol.RTM. was blended in a stirred glass reactor 
and 1.8 parts concentrated H.sub.2 SO.sub.4 added as esterification 
catalyst. The mixture was slowly heated to 112.degree. C., held at 
112.degree. C. for an additional 165 minutes and then cooled to give 205 
parts of a neat ester (VSE-1C) containing 40.5 weight percent of the 
surfactant ester and 59.5 weight percent of unreacted methacrylic acid. 
D. n-Octyloxypoly(ethyleneoxy).sub.19 ethyl Methacrylate 
In a similar manner the n-octyl polyethylene glycol ether obtained by 
condensation of n-octanol with 20 moles of ethylene oxide was esterified 
with excess methacrylic acid using sulfuric acid as a catalyst. A 
conversion of about 90 percent was obtained in two hours at 
110.degree.-120.degree. C. 
E. Hexadecylpoly(ethyleneoxy).sub.39 ethyl Methacrylate 
A mixture of 148 parts (0.058 mole) of hexadecylpoly(ethyleneoxy).sub.39 
ethanol, 255 parts (2.98 moles) of methacrylic acid, 0.06 part of 
hydroquinone and 0.06 part of Ionol.RTM. and 3.6 parts concentrated 
H.sub.2 SO.sub.4 was heated at 100.degree.-112.degree. C. for two hours 
yielding 403.5 parts of a solution containing 37.7 percent of vinyl 
surfactant ester (VSE-1E) and 62.3 percent of excess methacrylic acid. 
F. Methoxypropoxypoly(butyleneoxy).sub.4 (ethyleneoxy).sub.19 -ethyl 
Methacrylate 
The direct sulfuric acid catalyzed esterification process of Example 1A was 
used to prepare the above ester from the monomethyl ether of propylene 
glycol (Dowanol.RTM. PM from The Dow Chemical Company) condensed with four 
moles of butylene oxide and then 20 moles of ethylene oxide using an 
alkaline catalyst. The neat vinyl surfactant ester (VSE-1F) can be used 
without further purification in the preparation of the liquid emulsion 
copolymer. 
Other mono C.sub.8 -C.sub.20 alkyl glycol ether surfactants can be 
similarly esterified to provide vinyl surfactant esters with controlled 
hydrophilic-lipophilic balance. 
EXAMPLE 2 
Liquid Emulsion Polymerization Process 
The following are typical procedures for the preparation of the liquid 
emulsion polymers. 
LEP-2A--48.0 MAA/42.0 EA/10.0 VSE-1A 
The polymerization is carried out in a stainless steel, jacketed reactor 
equipped with stirrer and feed pumps using the concurrent addition 
technology of Miller et al. U.S. Pat. No. 3,563,946 in which separate 
monomer mix and aqueous feed solutions are added concurrently to an 
initial aqueous reactor charge stirred at 90 rpm and preheated to a 
desired temperature. When the addition of monomer and aqueous initiator is 
completed, normally in about 2-4 hours, the emulsion is stirred an 
additional 1.5 hours to finish the polymerization. Then the reactor is 
cooled and the liquid emulsion polymer filtered through 100 and 200 mesh 
screens. 
A typical recipe and reaction conditions are: 
______________________________________ 
(1) Initial Reactor Charge* 
374.0 parts Condensate water 
0.0075 part Versenex.RTM. 80 chelant 
(40% solids) 
2.0 parts Gafac.RTM. RE-610 anionic 
surfactant 
(2) Monomer Mix - Feed Rate - 4 hours 
48.0 parts Methacrylic acid (MAA) 
42.0 parts Ethyl acrylate (EA) 
10.0 parts Vinyl surfactant ester 
(VSE-1A) 
6.0 parts Igepal.RTM. CO-530 nonionic 
surfactant 
(3) Aqueous Feed Mix - Feed Rate - 4 hours 
69.8 parts Condensate water 
0.0025 part Versenex.RTM. 80 chelant (40%) 
0.4 part Sodium hydroxide 
2.0 parts Dowfax.RTM. 2A1 anionic 
surfactant (45% solids) 
1.0 part Gafac.RTM. RE-610 
0.5 part Sodium persulfate 
______________________________________ 
*Notes: 
Quantities are in parts by weight based on 100 parts total monomer 
Versenex.RTM. 80 sodium diethylenetriaminepentaacetic acid, 40% active 
solids from The Dow Chemical Company 
Gafac.RTM. RE610 a nonylphenoxypoly(ethyleneoxy)phosphate ester in free 
acid form from GAF 
VSE1A neat vinyl surfactant ester of Example 1A (100% active basis) 
Igepal.RTM. CO530 nonylphenoxypoly(ethyleneoxy).sub.5 ethanol from GAF 
Dowfax.RTM. 2A1 sodium dodecyldiphenyl ether disulfonate from The Dow 
Chemical Company 
Conditions: 
Addition temperature--70.degree. C., 
Agitation--230 rpm 
Cookdown--80.degree. C., 1.5 hours. 
The resulting liquid emulsion polymer contained 20.1 weight percent solids 
at pH 3.5 and had a 1 percent aqueous solution viscosity in ammonium salt 
form at pH 9 of 400 cps (Brookfield Model LVT, #2 spindle, 12 rpm, 
25.degree. C.). 
LEP-2B--42.0 MAA+6.0 IA/42.0 EA/10.0 VSE-1A 
Using the same polymerization recipe and conditions, a liquid emulsion 
polymer was prepared in which 6 parts of itaconic acid was substituted for 
6 parts of methacrylic acid. The resulting liquid product contained 19.9 
weight percent solids at pH 3.5 and had a 1 percent aqueous solution 
Brookfield viscosity of 1090 cps in ammonium salt form. 
LEP-2C-1--48.3 MAA/41.7 EA/10.0 VSE-1A 
In like manner a copolymer of 48.3 MAA/41.7 EA/10.0 VSE-1A was prepared 
which contained 20.0 weight percent solids and had a 1 percent aqueous 
solution Brookfield viscosity of 390 cps in ammonium salt form (cf 
Figure). 
LEP-2C-2, LEP-2C-3, LEP-2C-4 and LEP-2C-5 
These liquid emulsion polymers differ from LEP-2C-1 in the proportion of 
components. The compositions are shown in Table I. 
LEP-2D-1--42.0 MAA/37.2 EA/20.8 VSE-1B 
Several runs were made in 2 liter or 2 gallon reactors using the process of 
LEP-2E and the methacrylic ester of nonylphenoxypoly(ethyleneoxy).sub.39 
ethanol (VSE-1B) and the above monomer mix. Very clean emulsion polymers 
were obtained after filtration, containing about 20 weight percent solids 
and having an average particle size of about 1100-1300 A. 
LEP-2D-2, LEP-2D-3, LEP-2D-4 and LEP-2D-5 
These liquid emulsion polymers differ from LEP-2D-1 in the proportion of 
components. The compositions are shown in Table I. 
LEP-2E--47.8 MAA/42.0 EA/10.2 VSE-1C 
A stirred glass reactor was charged with 271 parts of water, 2.0 parts of 
Conco Sulfate 219 (sodium salt of ethoxylated, sulfated lauryl alcohol 
from Continental Chemical Co.) and 0.1 part of Versenex.RTM. 80 (40 
percent). The reactor charge was purged with nitrogen while stirring and 
was heated to 69.degree. C. 
A monomer mixture of 24.7 parts of methacrylic acid, 31.6 parts of ethyl 
acrylate, 19.0 parts of the product solution of Example 1-C containing 
40.5 percent of vinyl surfactant ester-1D and 59.5 percent of methacrylic 
acid and 2.0 parts Conco Sulfate 219 was prepared in a dropping funnel. 
To the preheated aqueous reactor charge was added 0.13 part of potassium 
persulfate and about 7 parts of the monomer mixture. Then the remainder of 
the monomer mixture was added over about 3 hours while keeping a reaction 
temperature of 69.degree.-70.degree. C. After stirring an additional 2.25 
hours at 70.degree. C., the liquid emulsion polymer was cooled and 
filtered. The product (341 parts) contained 21.4 percent solids and had a 
Brookfield viscosity of 9200 as a 1 percent aqueous solution in ammonium 
salt form. 
LEP-2F--42.2 MAA/37.2 EA/20.6 VSE-1D 
Using the general procedure of LEP-2A, a monomer mix of 42.2 parts of 
methacrylic acid, 37.2 parts of ethyl acrylate and 20.6 parts of 
octyloxypoly(ethyleneoxy).sub.19 ethyl methacrylate (VSE-1D) was 
copolymerized to give a stable emulsion copolymer containing 21.7 percent 
solids and having a 1 percent Brookfield LVT viscosity of 450 cps when 
neutralized with NH.sub.4 OH. 
LEP-2G-1--46.8 MAA/41.4 EA/11.8 VSE-1E 
In a similar manner a monomer mix of 18.5 parts of methacrylic acid, 28.0 
parts of ethyl acrylate, 21.0 parts of the solution from Example 1-E which 
contained 37.7 percent of hexadecyloxypoly(ethyleneoxy).sub.39 -ethyl 
methacrylate (VSE-1E) and 62.3 percent of methacrylic acid and 0.2 part of 
dodecyl mercaptan was copolymerized at 59.degree.-62.degree. C. using 0.09 
part potassium persulfate initiator to give a stable emulsion copolymer 
containing 20.5 percent solids and having a 1 percent Brookfield LVT 
viscosity of 450 cps when neutralized with NH.sub.4 OH. 
LEP-2G-2 49.6 MAA/44.1 EA/6.3 VSE-1E 
This liquid emulsion polymer differs from LEP-2G-1 in the proportion of 
components. 
LEP-2H--48.3 MAA/41.7 EA/10.0 VSE-1F 
In another run a copolymer of 48.3 MAA/41.7 EA/10.0 VSE-1F was prepared 
from the methoxypropoxypoly(butyleneoxy)(ethyleneoxy)ethyl methacrylate of 
Example 1-F. It contained about 20 weight percent solids and had a 1 
percent aqueous solution Brookfield viscosity of 288 cps in ammonium salt 
form. 
It was found that increasing the polymerization temperature from 
60.degree.-80.degree. C. had little effect on product efficiency in paint. 
But, the thickening efficiency of these products decreased as the nonionic 
vinyl comonomer was changed from ethyl acrylate to butyl acrylate to 
2-ethylhexyl acrylate and to methyl methacrylate. Thickening efficiency 
increased with increasing alkyl chain length from C.sub.8 -C.sub.16 alkyl 
in the alkylphenoxy surfactant ester. 
EXAMPLE 3 
Use as a Thickener for Latex Paint 
The utility of the new liquid emulsion polymers as a thickener for latex 
paint is illustrated by data obtained with several latex paint 
formulations and tests. 
______________________________________ 
Formulation 3A - Interior Flat Latex Paint 
Ingredients* Lbs Gallons 
______________________________________ 
A. Water 300 36.06 
Pigment dispersant (25% Tamol.RTM. 731) 
12 1.31 
Defoamer (Drew L-475) 2 0.26 
Preservative (Dowicil.RTM. 75) 
1 0.08 
Surfactant (Triton.RTM. X-100) 
5 0.56 
Aluminum silicate (ASP-400) 
100 4.66 
CaCO.sub.3 (snowflake white) 
125 5.54 
Titanium dioxide (Ti-Pure.RTM. R-931) 
250 7.79 
B. Ethylene glycol 25 3.00 
Glycol ether (Texanol) 10 1.26 
Everflex E.RTM. latex (55%) 
250 27.78 
C. LEP Thickener and water** 
95.6 11.47 
1175.6 99.77 
______________________________________ 
*Notes: 
Tamol.RTM. 731 sodium salt of maleic anhydride/diisobutylene copolymer 
from Rohm & Haas 
Drew L475 liquid defoamer from Drew Chemical Corp., Parsippany, NJ 07054 
Dowicil.RTM. 75 1(3-chloroallyl)-3,5,7-triaza-1-azoniaadamantane chlorid 
to which sodium bicarbonate has been added, from The Dow Chemical Co. 
Triton.RTM. X100 octylphenoxypolyethoxyethanol from Rohm & Haas 
ASP400 Pigment grade aluminum silicate from Engelhard Minerals & Chem 
Corp., Iselin, NJ 
Snowflake White Pigment grade calcium carbonate from Thompson, Weinmann 
Co., Cartersville, GA 30120 
TiPure.RTM. R931 TiO.sub.2 pigment from duPont 
Texanol 2,2,4trimethylpentanediol-1,3 monoisobutyrate from Eastman 
Chemical Products, Inc., Kingsport, TN 37662 
Everflex E.RTM. latex vinyl acetateacrylic copolymer latex, sometimes 
called "vinylacrylic latex" or less commonly "vinylacrylate latex" from 
W. R. Grace Co. 
**LEP Thickener normally about 1.0-6.0 lbs (100% solids basis)/100 gal 
plus water to balance 
To prepare a stock paint base, the A ingredients are ground together at 
high speed for 20 minutes using a Cowles grinder. Then at reduced speed 
premixed ethylene glycol and glycol ether are added followed by the 
Everflex E.RTM. latex. The liquid emulsion polymer thickener (20 percent 
solids) and appropriate amount of water can be added immediately or later 
as desired for test purposes. 
______________________________________ 
Formulation 3B - Interior Semigloss Latex Paint 
Ingredients* Lbs Gallons 
______________________________________ 
A. Water 93 11.18 
Pigment dispersant (25% Tamol.RTM. 731) 
11 1.20 
Defoamer (Nopco.RTM. NDW) 
2 0.27 
Propylene glycol 32 3.84 
Preservative (Dowicil.RTM. 75) 
1.3 0.10 
Titanium dioxide (Ti-Pure.RTM. R-900) 
275 7.95 
B Defoamer (Nopco.RTM. NDW) 
4 0.53 
Surfactant (Triton.RTM. GR7M) 
2 0.23 
Surfactant (Dowfax.RTM. 2A1) 
2 0.21 
Rhoplex.RTM. AC 490 (46.5%) 
590 66.67 
Propylene glycol 32 3.84 
Phenoxyethanol coalescing agent 
10 1.09 
C. LEP Thickener and water** 
74.0 8.87 
1128.3 105.98 
______________________________________ 
*Notes: 
Tamol.RTM. 731 sodium salt of maleic anhydride/diisobutylene copolymer 
from Rohm & Haas 
Nopco.RTM. NDW nonionic liquid defoamer from Diamond Shamrock Chemical 
Process Div. 
Dowicil.RTM. 75 1(3-chloroallyl)-3,5,7-triaza-1-azoniaadamantane chlorid 
to which sodium bicarbonate has been added, from The Dow Chemical Co. 
TiPure.RTM. R900 TiO.sub.2 pigment from duPont 
Triton.RTM. GR7M dioctyl sodium sulfosuccinate from Rohm & Haas 
Dowfax.RTM. 2A1 sodium dodecyldiphenyl ether disulfonate from The Dow 
Chemical Co. 
Rhoplex.RTM. AC 490 acrylic emulsion latex from Rohm & Haas 
**LEP Thickener normally about 1.0-6.0 lbs (100% solids basis)/100 gal 
plus water to balance 
To prepare a stock paint base, the A ingredients are ground together at 
high speed for 20 minutes using a Cowles grinder. Then at reduced speed 
the B ingredients including premixed propylene glycol and phenoxyethanol 
are added. The emulsion polymer thickener (20 percent solids) and the 
balance of the water can be added immediately or later as desired for test 
purposes. 
Procedures 
A. Thickener Addition--The liquid emulsion polymers can be incorporated in 
latex paints in several ways: 
1. Addition of the emulsion polymer to the final paint as liquid dispersion 
with subsequent neutralization with aqueous NH.sub.4 OH (28 percent) to a 
pH&gt;7. 
2. Presolubilization of the dispersion by diluting it with water and then 
adding sufficient alkali (NH.sub.4 OH or NaOH) with agitation. Once a 
clear solution has been obtained this can be post added to the final 
paint. 
3. Addition of the thickener to the pigment grind after the pigment has 
been dispersed and then the addition of sufficient alkali (NH.sub.4 OH or 
NaOH) to solubilize the thickener. It is recommended that the pigment 
grind be as dilute as possible prior to solubilization of the thickener 
dispersion. 
For experimental purposes, addition of the liquid emulsion polymer to a 
stock base paint followed by pH adjustment as necessary is particularly 
convenient (Method 1). 
B. Evaluation--Properties of paint thickened with the liquid emulsion 
polymers are evaluated using standard procedures recommended by ASTM 
Committee D-1 Subcommittee D-42 and paint companies for determining such 
properties as paint viscosity, stability, flow and leveling, brushability, 
spatter, hiding power, color compatibility and gloss. For research 
purposes, the following tests for the paint viscosity, flow and leveling 
are particularly useful: 
1. Stormer Viscosity--(ASTM Method D 562-55). The paint viscosity is 
measured with a Stormer Viscosimeter 24 hours after preparation. A 
viscosity of about 85-105 Kreb Unit (KU) is desired for most commercial 
latex paints. Accelerated stability tests often use Stormer viscosity 
measurements at 25.degree. C. of samples held at 120.degree. F. 
(49.degree. C.) for 2-4 weeks. 
2. Leneta Leveling Test--(The Leneta Co., Ho-Ho-Kus, NJ 07423). A paint 
sample is drawn down using a Leneta leveling test blade and the dried 
paint film compared visually with eleven Leneta levelness standards 
numbered 0-10 with 10 being perfect leveling. 
3. Leneta Anti-Sag Test--(The Leneta Co., Ho-Ho-Kus, NJ 07423). A 
presheared sample of paint is drawn down with the Leneta anti-sag meter on 
Leneta drawdown chart form 7B positioned horizontally on a flat glass or 
metal plate. The chart is then immediately placed in a vertical position 
with the paint stripes horizontal and left edge (thinnest stripe) at the 
top, and allowed to dry. Each stripe, ranging in wet film thickness from 3 
to 12 mils, is considered as having the same rating number as the notch by 
which it has been applied. The highest number (thickest) stripe that does 
not touch the one below itself is referred to as the index stripe, and its 
number is the Anti-Sag index of the paint. The practical interpretation of 
ratings is empirical and strongly subjective. Optimum sag resistance 
depends on the type of coating, but in general, an index of 8 through 12 
is considered good to excellent. 
4. Scrub Resistance--ASTM Method D-2486-66T. This test is normally run 
without the shim and provides an accelerated measure of wall paints to 
scrub erosion. 
5. Color Acceptance--A test paint is prepared by mixing 0.5 g of color tint 
with 24.5 g of formulated paint and drawn down on a primed-unprimed chart 
(Leneta 1B) using a 7 mil gap clearance blade. A 2-3 cm diameter circular 
area overlapping the primed-unprimed chart surface is rubbed with a finger 
until decided resistance is felt. The film is dried and rated as: (1) 
acceptable-no visual difference in rubbed area; (2) pigment 
flocculation-rubbed area lighter in color or (3) colorant 
flocculation-rubbed area darker in color. 
6. Gloss--ASTM Method D-523-67 is used to measure the Gardner 60.degree. 
gloss of paint test panels. A gloss rating of 30-65 generally desirable 
for interior semigloss latex paints. 
C. Table I 
Table I presents typical test results for an interior flat latex paint and 
an interior semigloss latex paint prepared as described for Formulations 
3A and 3B using the representative liquid emulsion polymers described in 
Example 2. 
Test results such as shown in Table I demonstrate the utility of the 
water-based liquid emulsion polymers described herein as a pH responsive 
thickener for aqueous compositions. By appropriate adjustment of monomer 
ratios, polymerization conditions and final product formulations, the 
liquid emulsion polymers can be tailored to give optimum thickening for 
many applications including particularly those containing natural, 
synthetic and artificial latexes. 
TABLE I 
__________________________________________________________________________ 
LIQUID EMULSION POLYMER IN LATEX PAINT 
Emulsion Polymer 
Evaluation (3)* 
Comonomers, Wt % (1)* (2)* Paint 
LEP 
Visc 
LEP 
(A) R COOH 
(B) Co-- 
(C) VSE 
% Solids 
1% Visc 
Base 
Wt KU LL LAS 
__________________________________________________________________________ 
2A 48.0 MAA 
42.0 EA 
10.0 1A 
20.1 400 3A 4.5 
101 7 12 
3B 2.75 
85 5 12 
2B 42.0 MAA 
42.0 EA 
10.0 1A 
19.9 1090 3A 3.0 
86 7 &lt;3 
+6.0 IA 3B 2.5 
79 5 12 
2C-1 
48.3 MAA 
41.7 EA 
10.0 1A 
19.8 390 3A 4.5 
99 5 12 
3B 2.5 
82 5 12 
2C-2 
48.3 MAA 
31.7 EA 
20.0 1A 
19.8 310 3A 4.5 
94 6 12 
3B 2.5 
79 5 12 
2C-3 
38.3 MAA 
51.7 EA 
10.0 1A 
20.1 870 3A 4.5 
96 5 12 
3B 2.5 
81 5 12 
2C-4 
38.3 MAA 
41.7 EA 
20.0 1A 
19.8 220 3A 4.5 
83 7 10 
3B 2.5 
78 5 12 
2C-5 
31.2 MAA 
45.0 EA 
10.0 1A 
21.9 7300 3A 5.0 
101 6 12 
+13.8 AA 3B 2.75 
106 5 12 
2D-1 
42.0 MAA 
37.2 EA 
20.8 1B 
21.6 1100 3A 5.0 
70 -- -- 
3B 3.5 
119 -- -- 
2D-2 
42.1 MAA 
18.6 EA 
20.8 1B 
21.8 800 3A 5.0 
94 8 9 
+18.6 S 3B -- -- -- -- 
2D-3 
42.0 MAA 
37.2 S 20.8 1B 
21.5 600 3A 5.0 
&lt;60 -- -- 
3B 3.5 
83 -- -- 
2D-4 
42.2 MAA 
32.6 EA 
6.6 1B 
19.8 100 3A -- -- -- -- 
+18.6 VAc 3B 5.0 
106 3 12 
2D-5 
18.7 MAA 
55.1 EA 
11.5 1B 
20.1 18400 
3A -- -- -- -- 
+15.0 HEA (5%) 3B -- -- -- -- 
2E 47.8 MAA 
42.0 EA 
10.2 1C 
21.4 9200 3A 3.5 
110 5 12 
3B 2.0 
106 3 12 
2F 42.2 MAA 
37.2 EA 
20.6 1D 
21.7 450 3A 5.0 
77 -- -- 
3B 5.0 
98 3 12 
2G-1 
46.8 MAA 
41.4 EA 
11.8 1E 
20.5 21000 
3A 5.0 
130 4 12 
3B 2.5 
128 4 12 
2G-2 
49.6 MAA 
44.1 EA 
6.3 1E 
19.0 325 3A 5.0 
98 9 10 
3B 3.0 
112 5 12 
2H 48.3 MAA 
41.7 EA 
10.0 1F 
20.0 288 3A 4.5 
102 3 12 
3B 2.5 
93 4 12 
__________________________________________________________________________ 
*Notes: 
(1) Comonomers, wt % based on total monomers 
(A) MAA methacrylic acid 
IA itaconic acid 
AA acrylic acid 
(B) EA ethyl acrylate 
S styrene 
HEA 2hydroxyethyl acrylate 
VAc vinyl acetate 
(C) Vinyl surfactant ester from 
1A nonylphenoxypoly(ethyleneoxy).sub.9 ethanol 
1B nonylphenoxypoly(ethyleneoxy).sub.39 ethanol 
1C dodecylphenoxypoly(ethyleneoxy).sub.10 ethanol 
1D octyloxypoly(ethyleneoxy).sub.19 ethanol 
1E hexadecyloxypoly(ethyleneoxy).sub.39 ethanol 
1F methoxypropoxypoly(butyleneoxy).sub.4 (ethyleneoxy).sub.19 ethanol 
(2) Liquid emulsion polymer 1 percent Brookfield Model LVT viscosity, pH 
9, #2 spindle at 12 rpm, 25.degree. C. 
(3) Evaluation in latex paint base 
Formulation 3A interior vinyl acrylic flat latex paint 
Formulation 3B interior acrylate semigloss latex paint 
LEP, wt lbs LEP thickener (100% solids basis)/100 gallons 
Viscosity 24 hr Stormer viscosity, KU 
LL Leneta Leveling 0-10 
LAS Leneta AntiSag 0-12 
D. Table II 
Table II presents typical test results comparing two liquid emulsion 
polymer thickeners with three commercial cellulose ether thickeners 
commonly used in latex paints. The effective thickening observed even with 
a lower viscosity LEP product suggests association of the LEP thickener 
with other components of the paint formulation as well as hydration by 
water. 
TABLE II 
______________________________________ 
COMISON OF THICKENERS 
Paint Thickener 
Haake Visc. 
Test Thickener 
1% Visc. Base wt Visc. KU 
______________________________________ 
3D-1 LEP-2A 400 3A 4.5 3.65 101 
3B 2.75 0.9 85 
3D-2 LEP-2E 9200 3A 3.5 -- 110 
3B 2.0 -- 106 
3D-3 HEC 1100-1450 3A 5.0 -- 96 
3B 3.25 -- 94 
3D-4 HEMC 800-1050 3A 5.25 -- 88 
3B 3.5 -- 91 
3D-5 MC-J 1000-1500 3A 4.5 1.75 95 
3B 2.5 1.3 80 
______________________________________ 
Notes*: 
LEP2A: 48.0 MAA/42.0 EA/10.0 VSE1A 
LEP2E: 47.8 MAA/42.0 EA/10.2 VSE1C 
HEC: Hydroxyethyl cellulose QP 15,000 (Union Carbide Corp) 
HEMC: Hydroxyethyl methylcellulose XD7603.03 (The Dow Chemical Co.) 
MCJ: Hydroxypropyl methylcellulose Methocel.RTM. J20MS (The Dow Chemcial 
Co.) 
Paint Base: Formulation 3A or 3B 
Thickener, wt: Lbs (100% solids)/100 gal 
Haake visc.: Viscosity (poise) at 10,000 sec.sup.-1 
Visc. KU: 24 hr Stormer viscosity 
E. To illustrate a more detailed evaluation of a liquid emulsion polymer as 
a thickener for a latex paint, Table III presents typical data for the 
liquid emulsion polymer described in Example 2A (48.0 MAA/42.0 EA/10.0 
VSE-1A; 20.1 percent solids, 1 percent viscosity of 305 cps at pH 9.0) 
used as a thickener in two paint formulations. For comparison, similar 
data for a commercial cellulose ether thickener is also given. Note that 
the liquid emulsion polymer is more efficient as a thickener, provides 
improved flow and leveling with markedly reduced spattering and yet 
retains many of the desirable properties of the cellulose ether thickener. 
Further rheological study of the liquid emulsion polymers suggests a 
controlled interaction or association of the LEP with the latex and 
pigment particles as a significant factor in the improved film build (one 
coat hiding) and reduced spray and spattering from roller application. 
TABLE III 
______________________________________ 
LATEX PAINT PERFORMANCE 
Vinyl-Acrylic 
Acrylic 
Paint Type Flat Semigloss* 
Thickener LEP-2A MC-J LEP-2A MC-J 
______________________________________ 
Loading (lbs/100 gal) 
4.5 4.5 2.5 2.5 
Stormer Visc. (24 hr KU) 
101 95 84 80 
Leneta Leveling 
7/10 4/10 5/10 4/10 
Leneta Anti-Sag 
11/12 9/12 12/12 12/12 
Gardner 60.degree. Gloss 
-- -- 43 43 
Scrub (cycles) 463.sup.1 
658.sup.1 
1075.sup.2 
1081.sup.3 
Color Acceptance.sup.4 
OK OK OK Poor 
Stormer Visc. 
(4 wks, 120.degree. F.; KU) 
103-107 95 81 94-92 
Paint pH 9.4 8.5 9.2 9.1 
Spattering Minimal Exces- Minimal 
Exces- 
sive sive 
______________________________________ 
Notes*: 
VinylAcrylic Interior Flat Latex Formulation 3A 
Acrylic Semigloss Latex Formulation 3B 
MCJ Methocel.RTM. J20MS (The Dow Chemical Company) 
.sup.1 Avg. of 4 tests 
.sup.2 Avg. of 2 tests 
.sup.3 One test 
.sup.4 Color acceptance: Borden Aquablak G; Tenneco Thalo Blue, Thalo 
Green and Medium Yellow Rubbed up. 
EXAMPLE 5 
LEP Thickeners in Other Aqueous Systems 
The wide utility of the liquid emulsion polymers as thickeners for aqueous 
compositions including inorganic solutions and slurries is indicated by 
data such as the following: 
A. Varying amounts of several inorganic salts were added to 1 percent 
aqueous solutions of LEP-2A (pH 9) and the Brookfield viscosity of the 
resulting solutions determined. Typical results are shown in Table IV. 
TABLE IV 
______________________________________ 
VISCOSITY, CPS AT 25.degree. C., pH 9 
Conc: 
Salt 0% 0.25% 0.50% 0.75% 1.00% 
______________________________________ 
NaCl 300 1090 1200 1125 850 
Na.sub.2 SO.sub.4 
300 780 910 920 905 
MgCl.sub.2 
300 &gt;2500 470 Floc -- 
______________________________________ 
B. To a slurry of 48.8 g of titanium dioxide (Ti-Pure.RTM. R-931 from 
duPont) and 50.2 g water having a 1 percent Brookfied viscosity of about 
100 cps was added 51.0 g of a 2 percent aqueous solution of LEP-2A having 
a pH of about 9 and a 1 percent Brookfield viscosity of 300 cps. The 
resulting thickened slurry had a 1 percent Brookfield viscosity of 4200 
cps. 
C. The effect of LEP-2A as a thickener for several unformulated 
vinyl-acrylic paint latexes was determined using several commercial 
latexes blended with a 2 percent aqueous solution of LEP-2A neutralized to 
pH 9 with NH.sub.4 OH. The blended aqueous compositions were adjusted to 
21 percent total solids and Brookfield viscosities were determined with 
results shown in Table V. 
TABLE V 
______________________________________ 
BROOKFIELD VISCOSITY* 
Latex* Initial 2% LEP-2A 
______________________________________ 
Everflex.RTM. E 10 cps 170 cps 
Airflex.RTM. 500 
7.5 cps 600 cps 
Ucar.RTM. 366 10 cps 290 cps 
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*Everflex.RTM. E Vinylacrylic copolymer (55% solids; W. R. Grace & Co.) 
Airflex.RTM. 500 Vinyl acetateethylene latex (55% solids; Air Products & 
Chemicals) 
Ucar.RTM. 366 Vinyl acetateacrylic copolymer latex, sometimes called 
"vinylacrylic latex" (55% solids; Union Carbide Corp.) 
Brookfield Viscosity #2 Spindle, 12 rpm, 25.degree. C., pH 9.0