Patent ID: 8906399

Claim:
A copolymer CP in the form of a polymer obtained by radical polymerization of at least three different monoethylenically unsaturated monomers M, where the at least three monomers M constituting the copolymer CP consist of: α) 5 to 60% by weight of at least one monoethylenically unsaturated monomer M1 having at least one sulfonic acid group, which is selected from monomers of the formula I in which n is 0, 1, 2, or 3; X is NR 5 ; R 1 is hydrogen or methyl; R 2 and R 3 are independently hydrogen or C 1 -C 4 alkyl; and R 5 is hydrogen or C 1 -C 4 alkyl, β3) 20 to 90% by weight of at least one monoethylenically unsaturated monomer M2a(1) which has a solubility in water at 20° C. in the range from 1 to <50 g/l, wherein the monomer M2a(1) is methyl methacrylate, and β4) 5 to 60% by weight of at least one second monomer M2a(2) which has a solubility in water at 20° C. of less than 1 g/l, and which are selected from the group consisting of decylacrylate, decylmethacrylate, myristyl methacrylate, myristyl acrylate, cetryl methacrylate, cetyl acrylate, stearyl methacrylate, and lauryl acrylate, all statements in % by weight being based on the total amount of monomers M constituting the copolymer CP.