| abstract |
The invention relates to copolymers which comprise, in copolymerized form,n a1) 30 to 90% by weight of at least one monoethylenically unsaturated C 3 -C 8 -carboxylic acid or of an anhydride or salt thereof, a2) 3 to 60% by weight of at least one monomer comprising sulfo groups, a3) 3 to 60% by weight of at least one nonionic monomer of the formula I nn H 2 C═C(R 1 )(CH 2 ) x O[R 2 —O] 0 —R 3 (I)n in which R 1 is hydrogen or methyl, R 2 are identical or different, linear or branched C 2 -C 6 -alkylene radicals which may be arranged in blocks or randomly, and R 3 is hydrogen or a straight-chain or branched C 1 -C 4 -alkyl radical, x is 0, 1 or 2 and o is a natural number from 3 to 50, a4) 0 to 30% by weight of one or more further ethylenically unsaturated monomers which are polymerizable with a1), a2) and a3), where the sum of a1), a2), a3) and a4) adds up to 100% by weight. |