Copolymers prepared by copolymerization of (a) a total of from 3.5 to 20%
by weight of at least one polymerizable acid selected from (a1)
ethylenically unsaturated C.sub.3-C.sub.10-monocarboxylic acid and (a2)
ethylenically unsaturated C.sub.4-C.sub.10-dicarboxylic acid or their
anhydrides, (b) from 4 to 10% by weight of at least one compound of the
general formula I ##STR00001## the sum of (a) and (b) being in the
range from 7.5 to 24% by weight, (c) from 60 to 92.5% by weight of at
least one compound of the general formula II ##STR00002## (d) from 0 to
0.5% by weight of at least one compound of the general formula III
##STR00003## (e) from 0 to 10% by weight of (meth)acrylonitrile, (f)
from 0 to 10% by weight of at least one conjugated diolefin, (g) from 0
to 10% by weight of at least one vinylaromatic compound of the general
formula IV ##STR00004## the variables being defined as follows: R.sup.1
and R.sup.2 are identical or different and are selected from hydrogen and
C.sub.1-C.sub.10-alkyl, R.sup.3 and R.sup.4 are identical or different
and are selected from hydrogen, C.sub.1-C.sub.20-alkyl, phenyl, or
R.sup.3 and R.sup.4 together are C.sub.2-C.sub.10-alkylene, substituted
or unsubstituted, R.sup.5 is selected from C.sub.1-C.sub.20-alkyl and
phenyl, R.sup.6, R.sup.7, R.sup.8, R.sup.9, R.sup.10 and R.sup.11 are
identical or different and are selected from hydrogen and
C.sub.1-C.sub.10-alkyl, x is an integer in the range from 0 to 12, y is
selected from 0 and 1, x being chosen to be not equal to 0 when y is 1, k
is an integer in the range from 0 to 3, it being possible for the
copolymers to be completely or partly neutralized with alkali or ammonium
and data in % by weight being based in each case on the total copolymer.