Crotonate-containing copolymers, processes for their preparation and their use as thickeners in aqueous systems and as sizing agents

Copolymers prepared by emulsion or solution copolymerization, initiated by free radicals, of unsaturated copolymerizable monomers, the copolymers being built up from PA1 (a) 1-45% by weight of ethylenically unsaturated carboxylic acids, PA1 (b) 0.5-30% by weight of a surface-active crotonic acid ester, PA1 (c) 30-85% by weight of methacrylic acid esters or acrylic acid esters of aliphatic (C.sub.1 -C.sub.18)-alcohols, PA1 (d) 0-40% by weight of other ethylenically unsaturated comonomers, PA1 (e) 0-3% by weight of polyethylenically unsaturated compounds and PA1 (f) 0-5% by weight of molecular weight regulators, and, if appropriate, the free acid groups of the copolymers subsequently having been partly or completely neutralized by addition of bases and converted into water-soluble or colloidally water-dispersible copolymer salts. In addition, processes for the preparation of the copolymers by solution or emulsion copolymerization and, if appropriate, subsequent conversion thereof into the copolymer salts, and the use of the products as viscosity-increasing and rheology-modifying substances in aqueous systems, in particular aqueous dispersions, preferably for thickening emulsion paints, emulsion gloss lacquers, textile printing pastes and paper printing pastes, and furthermore as sizing agents in the textile industry.

The invention relates to crotonate-containing copolymers, processes for 
their preparation and their use as viscosity-increasing substances in 
aqueous systems, in particular aqueous dispersions, with a surprising 
thickening and rheology-modifying action, and furthermore their use as 
sizing agents in the textile industry. 
Copolymers containing salts of methacrylic acid or acrylic acid and alkyl 
esters of these unsaturated carboxylic acids as well as a surface-active 
comonomer are already known. 
Thus, U.S. Pat. No. 3,652,497 describes copolymers of 5-30% by weight of an 
unsaturated (C.sub.2 -C.sub.6)-carboxylic acid and 70-95% by weight of an 
alkylphenoxypoly-(C.sub.2 -C.sub.3)-alkylene oxide (C.sub.2 
-C.sub.3)-alkyl ester of an unsaturated (C.sub.2 -C.sub.6)-carboxylic 
acid. The amount of surface-active, unsaturated ester in these copolymers 
is exceptionally high. As a consequence thereof and of the fact that 
exclusively an unsaturated carboxylic acid is used as the comonomer, their 
use as thickeners in aqueous systems results, for example, in an increased 
water-sensitivity of emulsion gloss paints which have been thickened with 
these copolymers. The content of water-soluble comonomers in the thickener 
copolymer is 100% here. 
European Pat. No. 0,003,235 describes the preparation of water-soluble 
copolymers of 2-80% by weight of an unsaturated (C.sub.3 
-C.sub.5)-carboxylic acid, less than 50% by weight of another 
ethylenically unsaturated monomer and 20-98% by weight of an acrylate or 
methacrylate, the alcohol component of which consists of an ethoxylated 
(C.sub.1 -C.sub.20)-alkanol. Because of the pronounced water-solubility of 
these copolymers, deterioration in the resistance to water also occurs 
here when they are used as thickeners in emulsion gloss paints 
(.gtoreq.50% by weight of water-soluble comonomers in the thickener 
copolymer). 
European Pat. No. 0,011,806 and European Pat. No. 0,013,836 describe 
copolymers consisting of 15-60% by weight of an unsaturated carboxylic 
acid, 15-80% by weight of a non-ionic monomer and 1-30% by weight of an 
ester of acrylic or methacrylic acid with an ethoxylated (C.sub.8 
-C.sub.20)-alkyl or (C.sub.8 -C.sub.16)-alkylphenyl or a (C.sub.8 
-C.sub.30)-alkyl, -alkyl-aryl or -polycyclic-alkyl alcohol. European Pat. 
No. 0,013,836 also describes the use of a crosslinking agent in amounts of 
0-1% by weight. In the neutralized state, the copolymers thus prepared 
have remarkable capacities as thickeners. The use of molecular weight 
regulators is also mentioned in European Pat. No. 0,013,836. 
U.S. Pat. No. 4,230,844 describes copolymers of 30-65% by weight of 
unsaturated carboxylic acid and 35-70% by weight of a surface-active 
unsaturated ester of an ethoxylated (C.sub.8 -C.sub.20)-alkyl alcohol. 
These copolymers thus also consist entirely of water-soluble monomers, so 
that their use as thickeners in emulsion gloss paints leads to a reduction 
in the water-resistance. 
European Pat. No. 0,013,836 and U.S. Pat. No. 4,230,844 describe the 
particular influence of the copolymers described above on the rheological 
properties of dispersed systems (for example latices, copolymer 
dispersions and emulsion gloss paints). Their action consists in the 
achievement of a balancing of technologically desirable properties of 
aqueous systems. For example, in a latex (an emulsion gloss paint and the 
like), both the high-shear viscosity, which influences the "film 
condition" and the brush-resistance, and the low-shear viscosity, which 
determines the film flow, can be influenced. 
The preparation of a surface-active crotonic acid ester is described in 
U.S. Pat. No. 4,075,411. The alcohols used here are exclusively 
ethoxylated (C.sub.8 -C.sub.20)-alkylphenols. Copolymerization of these 
crotonate monomers with other monomers is mentioned. However, the products 
in the examples do not contain unsaturated carboxylic acids and have 
neither thickening nor rheology-modifying properties. 
Nevertheless, the products described hitherto frequently only inadequately 
fulfill the technical requirements in practice in respect of their total 
spectrum of properties, such as water-resistance, gloss, 
molding-sharpness, flow, brush-resistance and effectiveness at low 
concentrations in aqueous emulsion paints. 
The invention was thus based on the object of preparing a 
rheology-modifying copolymer which, in as low as possible a concentration, 
i.e. with a high thickener capacity, can influence the rheology of aqueous 
systems with the particular effect that high viscosities coupled with 
high-shear gradients can be achieved in aqueous systems and that, in the 
final emulsion lacquer, the water-resistance of the latter is not impaired 
by soluble constituents. 
The requirement of high high-shear viscosity (=REL viscosity) is explained 
by the fact that, because of the brush-resistance, the consumer must use a 
significantly greater force to distribute the paint for example when 
brushing on paints with a relatively high high-shear viscosity, compared 
with paints which do not display an adequate brush-resistance on the 
brush. Control of the amount of paint brushed on per unit area, i.e. the 
coating thickness of the paint applied, is thereby established almost by 
itself when the abovementioned thickeners are used, because if brushing on 
is too extensive, the brush-resistance rises perceptibly because the shear 
gradient increases as the coating thickness decreases. The requirement of 
low low-shear viscosity is derived from the fact that this influences the 
flow of the paint after application. A low low-shear viscosity is thus a 
fundamental condition for good flow. An increase in the water-resistance 
of aqueous emulsion lacquers after application is a further requirement. 
Surprisingly, it has now been possible to achieve the object thus 
formulated by the copolymers characterized below. 
The invention relates to copolymers prepared by emulsion or solution 
copolymerization, initiated by free radicals, of unsaturated, 
copolymerizable monomers and, where relevant, subsequent partial or 
complete neutralization of the free acid groups of the copolymers by 
addition of bases, which copolymers are built up from 
(a) 1-45% by weight of ethylenically unsaturated (C.sub.3 
-C.sub.5)-monocarboxylic acids, ethylenically unsaturated (C.sub.4 
-C.sub.6)-dicarboxylic acids or monoesters thereof with aliphatic (C.sub.1 
-C.sub.8)-alcohols, or mixtures of these monomers, preferably methacrylic 
acid, acrylic acid, crotonic acid, maleic acid, monoalkyl maleates or 
mixtures thereof, 
(b) 0.5 to 30% by weight of a surface-active crotonic acid ester of the 
general formula I 
##STR1## 
in which n denotes a number from 2 to 100 and 
R denotes an aliphatic (C.sub.2 -C.sub.30)-radical, which can be linear or 
branched, a mono-, di- or tri-alkylphenyl radical with alkyl groups of, in 
each case, 4 to 12 carbon atoms or a block-copolymeric radical of the 
formula IIa or IIb 
##STR2## 
in which m represents a number from 10 to 100, p represents a number from 
0 to 100 and 
R.sup.1 represents H, crotyl, (C.sub.1 -C.sub.20)-alkyl, phenyl or 
alkylphenyl with (C.sub.1 -C.sub.20)-alkyl groups, or 
R denotes a perfluorinated or partially fluorinated (C.sub.1 
-C.sub.16)-alkyl radical, 
(c) 30-85% by weight of methacrylic acid esters or acrylic acid esters of 
aliphatic (C.sub.1 -C.sub.18)-alcohols or a mixture of these esters, 
(d) 0-40% by weight of other ethylenically unsaturated comonomers, 
preferably vinyl esters, vinyl-aromatics, ethylenically unsaturated 
nitriles, esters of ethylenically unsaturated monocarboxylic and 
dicarboxylic acids, where these have not already been listed above under 
(c), ethylenically unsaturated sulfonic acids or ethylenically unsaturated 
sulfonic acid derivatives, 
(e) 0-3% by weight of polyethylenically unsaturated compounds, preferably 
divinylbenzene, diallyl phthalate and butanediol diacrylate or 
dimethacrylate and 
(f) 0-5% by weight of molecular weight regulators, preferably 
dodecylmercaptan, tetrakis-mercaptoacetyl-pentaerythritol, carbon 
tetrachloride or bromotrichloromethane. 
On partial or complete neutralization, the copolymers become increasingly 
to completely water-soluble or colloidally dispersible in water. In the 
partially or completely neutralized form, they can act and be used as 
thickeners of aqueous systems with rheology-modifying properties in the 
abovementioned sense. 
The invention thus furthermore relates to the copolymers, according to the 
invention described above, in partially or completely base-neutralized 
water-soluble or colloidally water-dispersible form. 
A preferred application method for the copolymers according to the 
invention consists, for example, of admixing them (in their 
non-neutralized and in general water-insoluble acid form as solutions in 
suitable solvents or, in particular, as low-viscosity aqueous dispersions) 
with the aqueous or water-containing system to be thickened and then 
partially or completely neutralizing the resulting mixture with bases, 
such that the copolymers are converted into a water-soluble salt form, 
displaying their thickening and rheology-modifying action. 
Examples of preferred compounds of component (a) of the copolymers 
according to the invention are crotonic acid, maleic acid, itaconic acid 
and maleic acid monoesters and itaconic acid monoesters of straight-chain 
or branched (C.sub.1 -C.sub.8)-alcohols. Acrylic acid and methacrylic acid 
are particularly preferred. 
In the case of the monomers of component (b), preferred compounds of the 
formula I 
##STR3## 
in which n and R have the abovementioned meanings, are those where 
n=10-80, in particular n=20-50, and also those where 
R=n- or iso-(C.sub.2 -C.sub.30)-alkyl, preferably (C.sub.12 
-C.sub.20)-alkyl and in particular (C.sub.16 -C.sub.18)-alkyl, such as, 
for example, n- or iso-octyl, n- or iso-decyl, n- or iso-dodecyl, n- or 
iso-hexadecyl, n- or iso-octadecyl or mixtures of these radicals, so that, 
for example, crotonic acid esters with 10 ethylene oxide units and a 
C.sub.12 -alkyl radical or with 20 ethylene oxide units and an iso-octyl 
radical, or with 50 ethylene oxide units and a C.sub.18 -alkyl radical can 
result, or monoalkylphenyl with (C.sub.4 -C.sub.12)-n- or iso-alkyl 
groups, preferably C.sub.8 - or C.sub.9 -n- or iso-alkyl groups, such as, 
for example, iso-octylphenyl or iso-nonylphenyl, with which, for example, 
crotonic acid esters with 5 ethylene oxide units and an iso-octylphenyl 
radical, or with 11 ethylene oxide units and an iso-nonylphenyl radical 
can result, or dialkylphenyl with (C.sub.4 -C.sub.12)-n- or iso-alkyl 
groups, such as, for example, diisobutylphenyl, diisooctylphenyl or 
diisononylphenyl, with which, for example, crotonic acid esters with 20 
ethylene oxide units and a diisobutylphenyl radical, or 50 ethylene oxide 
units and a diisooctylphenyl radical, or 80 ethylene oxide units and a 
diisononylphenyl radical can result, or trialkylphenyl with (C.sub.4 
-C.sub.12)-n- or iso-alkyl groups, such as, for example, 
triisobutylphenyl, triisooctylphenyl or triisononylphenyl, with which, for 
example, crotonic acid esters of 11 ethylene oxide units and a 
triisobutylphenyl radical, or 23 ethylene oxide units and a 
triisononylphenyl radical, or 50 ethylene oxide units and a 
triisooctylphenyl radical, can result, or a radical of the formula IIa or 
IIb 
##STR4## 
preferably such a radical with m=20-80 and p=0-80, in particular 0-50, and 
preferably R.sup.1 =H, (C.sub.1 -C.sub.20)-n- or iso-alkyl, n- or 
iso-alkylphenyl with (C.sub.1 -C.sub.20)-alkyl groups, phenyl or crotyl, 
from which crotonic acid esters of ethylene oxide/propylene oxide 
copolymers with, for example, p=20, m=20 and an iso-butyl radical, or 
p=30, m=40 and a crotyl radical, or p=50 and m=80, or m=20, p=0 and a 
nonylphenyl radical, can result, or (C.sub.2 -C.sub.16)-perfluoroalkyl or 
partially fluorinated alkyl. 
Mixtures of the monomers mentioned can also be employed, in which case it 
should be taken into consideration that the compounds to be employed as a 
rule are prepared from industrial intermediates which may have, for 
example, a certain distribution range in respect of their degree of 
oxyethylation or their molecular weight distribution. 
Preferred compounds of component (c) are methyl, ethyl, isopropyl, 
isobutyl, tert.-butyl and n-butyl acrylate and methacrylate. The methyl 
and ethyl esters of acrylic and methacrylic acid are particularly 
preferred. 
Particularly suitable compounds of component (d) are: vinyl esters of 
(C.sub.1 -C.sub.12)-carboxylic acids, such as acetic acid, propionic acid, 
2-ethylhexanoic acid, versatic acid 9, versatic acid 10, lauric acid and 
furthermore unsaturated aromatic compounds, such as styrene or 
vinyltoluene, and furthermore esters of unsaturated monocarboxylic and 
dicarboxylic acids with C.sub.8 -alcohols or higher alcohols, such as 
acrylic and methacrylic acid esters, for example dodecyl acrylate or 
octadecyl methacrylate, or crotonic acid esters of (C.sub.1 
-C.sub.8)-alchols, such as, for example, methyl crotonate or 2-ethylhexyl 
crotonate, or maleic or itaconic acid esters with (C.sub.1 
-C.sub.8)-alcohols, such as, for example, dimethyl maleate, dibutyl 
maleate, di-2-ethylhexyl maleate or dimethyl itaconate, or acrylic acid 
monoesters or methacrylic acid monoesters of diols and triols, such as, 
for example, ethylene glycol, butene-1,4-diol, hexane-1,6-diol, glycerol 
and trimethylolpropane, or unsaturated nitriles, such as acrylonitrile or 
methacrylonitrile, or unsaturated sulfonic acids, preferably 
ethylenesulfonic acid or acrylamidopropanesulfonic acid, or, preferably, 
salts thereof, in particular alkali metal or ammonium salts. 
Particularly suitable compounds of component (e) are: diallyl phthalate, 
divinylbenzene, butanediol methacrylate, ethanediol dimethacrylate, 
hexanediol dimethacrylate, ethanediol diacrylate, butanediol diacrylate, 
hexanediol diacrylate, pentaerythritol triacrylate, trimethylolpropane 
triacrylate, tetraethylene glycol diacrylate, tripropylene glycol 
diacrylate and trimethylolpropane trimethacrylate. 
A copolymer built up from components (a) to (f) according to the invention 
can be prepared, for example, by conventional solution copolymerization 
initiated by free radicals in conventional solvents or in the form of a 
dispersion by conventional emulsion copolymerization. If the preparation 
is via emulsion copolymerization, the solids content of the resulting 
dispersion is preferably between 10 and 55% by weight. Emulsion 
copolymerization is the preferred preparation process, the surface-active 
comonomer (b) preferably being initially introduced into the aqueous 
phase. 
The conventional processes for copolymerization in organic media using free 
radical initiators can be used for preparation by solution 
copolymerization. Emulsion copolymerization can likewise be carried out by 
conventional methods, i.e. the conventional ionic and non-ionic 
emulsifiers can be used for emulsifying the monomers and stabilizing the 
latex. Examples of suitable anionic emulsifiers are: alkyl sulfates, 
alkylaryl sulfates, alkylarylsulfonates and alkali metal and/or ammonium 
salts of alkyl or alkylaryl polyglycol ethersulfates, and examples of 
suitable non-ionic emulsifiers are: oxyethylated fatty alcohols and 
oxyethylated alkylphenols. The amount of emulsifier used is in general 
0.3-5% by weight, based on the total weight of monomer. 
The invention thus furthermore relates to a process for the preparation of 
copolymers by emulsion or solution copolymerization, initiated by free 
radicals, of unsaturated, copolymerizable monomers and, where relevant, 
subsequent partial or complete neutralization of the free acid groups of 
the copolymers by addition of bases, which comprises copolymerizing, as 
monomers, 
(a) 1-45% by weight of ethylenically unsaturated (C.sub.3 
-C.sub.5)-monocarboxylic acids, ethylenically unsaturated (C.sub.4 
-C.sub.6)-dicarboxylic acids or monoesters thereof with aliphatic (C.sub.1 
-C.sub.8)-alcohols, or mixtures of these monomers, preferably methacrylic 
acid, acrylic acid, crotonic acid, maleic acid, monoalkyl maleates or 
mixtures thereof, 
(b) 0.5 to 30% by weight of a surface-active crotonic acid ester of the 
general formula I 
##STR5## 
in which n denotes a number from 2 to 100 and R denotes an aliphatic 
(C.sub.2 -C.sub.30)-radical, which can be linear or branched, a mono-, di- 
or tri-alkylphenyl radical with alkyl groups of, in each case, 4 to 12 
carbon atoms or a block-copolymeric radical of the formula IIa or IIb 
##STR6## 
in which m represents a number from 10 to 100, p represents a number from 
0 to 100 and 
R.sup.1 represents H, crotyl, (C.sub.1 -C.sub.20)-alkyl, phenyl or 
alkylphenyl with (C.sub.1 -C.sub.20)-alkyl groups, or 
R denotes a perfluorinated or partially fluorinated (C.sub.1 
-C.sub.16)-alkyl radical, 
(c) 30-85% by weight of methacrylic acid esters or acrylic acid esters of 
aliphatic (C.sub.1 -C.sub.18)-alcohols or a mixture of these esters, 
(d) 0-40% by weight of other ethylenically unsaturated comonomers, 
preferably vinyl esters, vinyl-aromatics, ethylenically unsaturated 
nitriles, esters of ethylenically unsaturated monocarboxylic and 
dicarboxylic acids, where these have not already been listed above under 
(c), ethylenically unsaturated sulfonic acids or ethylenically unsaturated 
sulfonic acid derivatives, 
(e) 0-3% by weight of polyethylenically unsaturated compounds, preferably 
divinylbenzene, diallyl phthalate and butanediol diacrylate or 
dimethacrylate and 
(f) 0-5% by weight of molecular weight regulators, preferably 
dodecylmercaptan, tetrakis-mercaptoacetyl-pentaerythritol, carbon 
tetrachloride or bromotrichloromethane, and, if appropriate, converting 
the resulting copolymer into a water-soluble or colloidally 
water-dispersible copolymer salt by neutralization with bases, preferably 
with alkali metal, ammonium or amine bases. 
The preferred procedure is emulsion copolymerization, and in this, in turn, 
the surface-active comonomer (b) is preferably initially introduced into 
the aqueous phase. The content of copolymer in the aqueous dispersions 
prepared according to the invention is preferably 10 to 55% by weight, in 
particular 25 to 50% by weight. 
The following factors, inter alia, should be considered when choosing the 
type and proportions of the comonomers (a) to (e). The use of the 
unsaturated carboxylic acids listed as component (a) contributes to 
ensuring easy dispersibility of the copolymers according to the invention 
in aqueous dispersion. In the partially or completely neutralized form, 
component (a) also, inter alia, contributes decisively to achieving the 
water-solubility or colloidal water-dispersibility of the copolymer salts 
according to the invention. 
It should also be taken into consideration that copolymerization of the 
particular comonomers used with one another must in principle be possible, 
and that it also actually takes place. In the simplest case, this can be 
estimated with the aid of the copolymerization parameters or the Q- and 
e-values (compare, for example, B. Brandrup, Immergut, Polymer Handbook, 
2nd edition (1975), John Wiley & Sons, New York). Under certain 
circumstances, when choosing certain comonomers (a)-(e), the monomer 
mixture ratio must be chosen according to how copolymerization is possible 
by varying the synthesis method and, inter alia, specifically the manner 
in which the monomer is metered in. Thus, if appropriate, under certain 
circumstances, copolymerization reactions can be forced by initially 
introducing one or more monomer components and only metering in the 
remaining monomer or the remaining monomer mixture in the course of the 
polymerization. In the case of emulsion copolymerization, whether the 
monomer is metered in by itself or as an aqueous emulsion may be of 
decisive importance in this connection. The same applies here also to the 
manner in which the emulsifier is added. Differences in respect of 
particle size, particle size distribution and stability of the copolymer 
dispersion can thereby be observed, depending on whether the emulsifier is 
initially introduced or whether it is metered in during the 
copolymerization. 
Component (b) is the constituent of the copolymers according to the 
invention which probably most contributes to the development of the 
desired overall properties for use in aqueous emulsion varnishes. Since 
crotonic acid esters undergo self-polymerization only with difficulty or 
not at all, their use in copolymerization reactions cannot lead to 
segments of surface-active crotonic acid esters in the copolymer. The 
action of the resulting copolymer as a thickener and rheology-modifier can 
be influenced by varying the length of the ethylene oxide chain in the 
crotonic acid ester. Thus, for example, the viscosity-increasing action of 
the copolymer in the high-shear and low-shear ranges in disperse aqueous 
systems increases as the ethylene oxide chain length increases. 
The relative amounts of components (a) to (d) can vary within a relatively 
wide range. They can preferably be (a) 1-45% by weight, (b) 0.5-30% by 
weight, (c) 30-85% by weight and (d) 0-40% by weight; (a) 5-40% by weight, 
(b) 1-25% by weight, (c) 40-80% by weight and (d) 0-35% by weight are 
particularly preferred; (a) 8-40% by weight, (b) 3-20% by weight, (c) 
50-75% by weight and (d) 0-30% by weight are very particularly preferred. 
The conventional water-soluble initiators which start free radical chains 
are preferably used in amounts of 0.01-2% by weight, based on the total 
amount of monomer, to initiate the emulsion copolymerization. Examples of 
these initiators are, inter alia, alkali metal persulfates or ammonium 
persulfate. The polymerization temperature is adjusted in the conventional 
manner according to the half-lives of the initiators. 
To increase the thickener capacity or for further influencing of the 
rheological properties of the dissolved copolymers in aqueous systems, it 
may in some cases be advantageous also to use a polyethylenically 
unsaturated compound as a comonomer. Comonomers of this type which can be 
used are crosslinking comonomers, such as, for example, diallyl phthalate, 
divinylbenzene, allyl methacrylate or ethylene glycol dimethacrylate. The 
amounts used can be varied within a range from 0 to 3% by weight, 
preferably 0 to 1% by weight, based on the total amount of monomer. During 
the polymerization, branches or networks develop which, after more or less 
complete neutralization of the copolymer, may lead to the formation of gel 
structures and hence to the development of specific rheological property 
profiles. 
Finally, the use of molecular weight regulators during the copolymerization 
leads to relatively low molecular weights of the copolymers. The viscosity 
of the aqueous solutions of such copolymers thus falls, compared with the 
non-regulated products. The possibility of adjusting the required balance 
between high high-shear viscosity and low low-shear viscosity in a 
controlled manner for specific application systems can in this way be 
improved. All compounds which have the property of transferring free 
radicals can be used as the regulators. Preferred examples here are 
mercaptans (monofunctional and polyfunctional), such as, for example, n- 
and t-dodecylmercaptan, tetrakis-mercaptoacetyl-pentaerylthritol and 
thioglycolic acid. However, other compounds can also be used as 
regulators, such as, for example .alpha.-methylstyrene, toluene, 
trichlorobromomethane and carbon tetrachloride. The amount of regulator 
used can thereby be varied within a range of 0 to 5% by weight, based on 
the total amount of monomer. 
The thickener capacity of copolymers according to the invention can 
additionally be influenced by the (further) addition of ionic or non-ionic 
emulsifiers to the aqueous system, especially before, but also after, the 
free acid groups of the copolymer have been neutralized. If, for example, 
0.01-5% by weight of the copolymer according to the invention (based on 
the solid) is used as a thickener for thickening an aqueous system 
containing dispersed solids, the advantageous range for any further 
amounts of emulsifier to be added is between 0.01 and 10% by weight (based 
on the solid). 
It has now been found, surprisingly, that the copolymers or copolymer salts 
or partial salts prepared according to the invention with a surface-active 
ester of crotonic acid have significantly higher thickener capacities in 
aqueous solution than comparable copolymers or salts thereof which have 
been prepared under identical conditions with corresponding surface-active 
esters of methacrylic acid or of acrylic acid instead of the 
surface-active crotonic acid ester. It has been possible to observe the 
better thickener capacity of the copolymers according to the invention 
both in the high-shear range (shear gradient D=10,000 s.sup.-1) and in the 
low-shear range (D=0.1 s.sup.-1). This has, inter alia, the advantage that 
smaller use amounts of the thickener according to the invention are 
required to impart certain rheological properties to aqueous systems, 
compared with the use of corresponding copolymers containing acrylate or 
methacrylate components instead of the crotonate component. 
The copolymers according to the invention are preferably used as thickeners 
in their partly or completely base-neutralized water-soluble or 
colloidally water-dispersible form for thickening aqueous systems and 
imparting to them particular rheological properties. Whilst the copolymers 
according to the invention in their free acid form are preferably 
water-insoluble products, their salts with bases, in particular the alkali 
metal, ammonium or amine salts, are water-soluble, giving clear solutions, 
or water-dispersible in colloidal form. The copolymers are preferably and 
advantageously used as thickeners in a manner such that they are first 
admixed as a low-viscosity solution in a suitable solvent or as an aqueous 
copolymer dispersion of low viscosity to the aqueous system to be 
thickened, and the resulting mixture, including, for example, all the 
pigments and lacquer constituents optionally contained therein, is then 
partly or completely neutralized or rendered slightly alkaline, for 
example to pH values of 5-10.5, in particular 8-9.5, by addition of a 
base. The copolymers are preferably mixed in the form of aqueous 
dispersions with the aqueous systems to be thickened. 
Preferred fields of use for the copolymers according to the invention are 
the thickening and viscosity adjustment of disperse aqueous systems, such 
as, for example, preferably, emulsion paints, emulsion gloss lacquers, 
textile printing pastes and paper printing pastes, and furthermore 
biocidally-active-compound dispersions for plant protection and combating 
pests, liquid fertilizers, emulsion cleaning agents, discharge pastes, 
de-icing agents or cosmetic formulations. A further interesting 
application of the copolymers according to the invention is their use as 
sizing agents, in the textile industry, which can easily be washed out by 
alkaline liquors or as sizing agent components. 
In aqueous emulsion gloss lacquers, for example, the use of the copolymers 
according to the invention particularly advantageously leads to the 
development of the rheological properties desired by the user, such as 
"high" high-shear viscosity and "low" low-shear viscosity. High high-shear 
viscosity is understood as meaning values between 2 and 3.5 poise at 
D=10,000 s.sup.-1, and low low-shear viscosity is understood as meaning 
values of about 50-100 poise at D=0.1 s.sup.-1 and below. 
The amounts of copolymers according to the invention to be used are not 
critical. However, in the case of use as a thickener, they are preferably 
in the range from 0.01 to 5% by weight of copolymer, based on the aqueous 
system to be thickened.

The invention is illustrated in more detail by the examples which follow. 
EXAMPLE 1 
Synthesis of the surface-active crotonic acid ester (b) 
828 g of oxyethylated (C.sub.16 -C.sub.18)-fatty alcohol (n=50) were dried 
azeotropically in 828 g of toluene. After about 1.5 hours, 55.8 g of 
crotonic anhydride were added. The solution was boiled under reflux for a 
further 2.5 hours. After cooling, the toluene was stripped off in vacuo. 
Yield: 883 g of a brownish-yellow, water-soluble product of waxy 
consistency. The conversion check was made by thin layer chromatography. 
The corresponding crotonic acid esters (a) and (c) to (o), which are 
likewise surface-active, were prepared from the oxyethylated alcohol 
components listed below under (a) and (c) to (o) analogously to the above 
instructions for the surface-active crotonic acid ester (b). 
______________________________________ 
Degree of 
oxyethylation 
(moles of 
Alcohol component ethylene oxide) 
______________________________________ 
(a) oxyethylated (C.sub.16 -C.sub.18)-fatty alcohol 
80 
(b) " 50 
(c) " 25 
(d) " 15 
(e) " 11 
(f) oxyethylated tributylphenol 
50 
(g) " 30 
(h) " 18 
(i) oxyethylated (C.sub.12 -C.sub.16)-perfluoro- 
8 
alcohol 
(j) oxyethylated (C.sub.12 -C.sub.16)-perfluoro- 
13 
alcohol 
(k) oxyethylated nonylphenol 
30 
(l) " 23 
(m) " 14 
(n) " 8 
(o) crotonate of a propylene 
oxide/ethylene oxide block 
copolymer 
______________________________________ 
EXAMPLE 2 
Synthesis of copolymers according to the invention by emulsion 
polymerization 
Preparation of sample 1 
28 g of the Na salt of an alkylaryl polyglycol ether-sulfate (50% strength 
by weight) were dissolved in 738 g of demineralized water (=E-water) in a 
(2 liter) 3-necked flask with a stirrer, reflux condenser and internal 
thermometer, and the solution was warmed to 80.degree. C., with stirring. 
10 ml of an initiator solution consisting of 0.25 g of ammonium persulfate 
in 50 g of E-water, and 50 g of a monomer mixture consisting of 252 g of 
ethyl acrylate, 63 g of acrylic acid and 35 g of surface-active crotonic 
acid ester (b) from Example 1 were added. The remainder of the monomer 
mixture was then metered in, starting after half an hour and over a period 
of 2 hours, together with the remainder of the initiator solution. When 
the metering in had ended, the mixture was after-heated for a further 
hour, stirring being continued, and the batch was then brought to room 
temperature. Solids content of the dispersion: 30.1% by weight. The 
percentage composition of the copolymer content of sample 1 is given in 
Table 1. 
Samples 2 to 12, likewise in dispersion form, were prepared from the 
particular monomer constituents and amounts listed in Table 1 in the same 
way as sample 1, by analogous emulsion polymerization reactions. The 
regulators and crosslinking agents also used in some cases were in each 
case admixed to the monomer mixture in the amounts given, based on the 
total amount of monomer. 
By neutralizing the dispersions with aqueous sodium hydroxide solution or 
with aqueous ammonia, it was possible to convert the copolymer 
constituents of samples 1 to 12 into water-soluble products with the 
desired thickening and rheology-modifying properties. 
TABLE 1 
__________________________________________________________________________ 
Composition of the copolymer constituents of dispersions 
1 to 12 in % by weight of monomer units, in each case 
based on the copolymer without the regulator and cross- 
linking agent contents. 
Surface 
acitve Cross- 
Meth- 
crotonate 
Regulator: 
Linking 
Ethyl acrylic 
from n-dodecyl- 
agent 
acrylate 
Acrylic acid 
acid Example 1(b) 
mercaptan 
divinyl- 
(% by 
(% by (% by 
(% by (% by benzene 
Sample No. 
weight) 
weight) 
weight) 
weight) 
weight) 
(% by weight) 
__________________________________________________________________________ 
1 72 18 -- 10 -- -- 
2 72 18 -- 10 0.2 -- 
3 72 18 -- 10 0.5 -- 
4 72 18 -- 10 1.0 -- 
5 80 20 -- -- -- -- 
6 80 20 -- -- 0.2 -- 
7 55 20 5 20 0.2 -- 
8 50 20 10 20 0.2 -- 
9 40 20 20 20 0.2 -- 
10 72 18 -- 10 0.2 0.25 
11 72 18 -- 10 0.2 0.5 
12 72 18 -- 10 0.2 1.0 
__________________________________________________________________________ 
EXAMPLE 3 
Samples 13 to 26 were prepared in dispersion form from the particular 
monomer constituents and amounts listed in Table 2 below in the same way 
as described in Example 2 by analogous emulsion polymerization reactions. 
The regulator also used in some cases was in each case admixed to the 
monomer mixture in the given amounts, based on the total amount of 
monomer. The designation of the surface-active crotonic acid ester in 
column 6 of Table 2 relates to the data in Example 1. 
By neutralizing the dispersions with aqueous sodium hydroxide solution or 
with aqueous ammonia, it was possible to convert the copolymer 
constituents of samples 13 to 26 into water-soluble products with the 
desired thickening and rheology-modifying properties. 
TABLE 2 
__________________________________________________________________________ 
Composition of the copolymer constituents of dispersions 
13 to 26 in % by weight of monomer units, in each case 
based on the copolymer without the regulator content. 
Meth- Surface- 
Surface- 
Regulator: 
Ethyl 
acrylic 
Acrylic active 
active 
n-dodecyl- 
acrylate 
acid acid Styrene 
crotonate 
crotonate 
mercaptan 
(% by 
(% by 
(% by 
(% by 
Example 1 
(% by 
(% by 
Sample No. 
weight) 
weight) 
weight) 
weight) 
from No. 
weight) 
weight) 
__________________________________________________________________________ 
13 40 45 -- -- 1g 15 -- 
14 40 40 -- -- 1i 20 0.1 
15 30 40 -- -- 1c 30 0.5 
16 45 35 -- -- 1h 15 0.3 
17 50 45 -- -- 1f 5 0.2 
18 60 30 -- -- 1l 20 -- 
19 45 25 -- -- 1j 30 0.2 
20 -- -- 10 80 1f 10 0.2 
21 -- -- 20 70 1f 10 0.2 
22 -- 20 10 60 1f 10 0.2 
23 -- 40 -- 55 1h 5 0.1 
24 -- 30 -- 65 1h 5 0.3 
25 -- 40 -- 40 1m 20 0.2 
26 -- 45 -- 45 1g 10 -- 
__________________________________________________________________________