Patent ID: 8362180

Claim:
A water-soluble, hydrophobically associating copolymer comprising at least (a) 0.1 to 20% by weight of at least one monoethylenically unsaturated, hydrophobically associating monomer (a), and (b) 25% by weight to 99.9% by weight of at least one monoethylenically unsaturated hydrophilic monomer (b) different therefrom, where the quantitative data are based in each case on the total amount of all of the monomers in the copolymer, wherein at least one of the monomers (a) is a monomer of the general formula (I) H 2 C═C(R 1 )—R 4 —O—(—CH 2 —CH(R 2 )—O—) k —(—CH 2 —CH(R 3 )—O—) l —R 5 (I) where the units —(—CH 2 —CH(R 2 )—O—) k and —(—CH 2 —CH(R 3 )—O—) l are arranged in block structure in the order shown in formula (I) and the radicals and indices have the following meaning: k: a number from 10 to 150, l: a number from 5 to 25, R 1 : H or methyl, R 2 : independently of one another, H, methyl or ethyl, with the proviso that at least 50 mol % of the radicals R 2 are H, R 3 : independently of one another, a hydrocarbon radical having at least 2 carbon atoms or an ether group of the general formula —CH 2 —O—R 2′ , where R 2′ is a hydrocarbon radical having at least 2 carbon atoms, R 4 : a single bond or a divalent linking group —O—(C n′ H 2n′ )— where n′ is a natural number from 1 to 6, R 5 : H or a hydrocarbon radical having 1 to 30 carbon atoms.