Anionic associative rheology modifiers

Polymer comprising as polymerized units

• a) 25 to 85% by weight of acrylic acid,
• b) 10 to 60% by weight of N-vinyl pyrrolidone,
• c) 0.5 to 10% by weight of at least one cationic monomer,
• d) 0.5 to 10% by weight of at least one of compounds d1) or d2)
• wherein
• the order of the alkylene oxide units is arbitrary,
• k and l
• independently of one another, are an integer from 0 to 1000, where the sum of k and l is at least 5,
• R8 is hydrogen or C1-C4-alkyl,
• R9 is C3-C30-alkyl, C8-C30-alkenyl or C8-C30 alkylaryl, and
• X is O or a group of the formula NR10, in which R10 is H, alkyl, alkenyl, cycloalkyl, heterocycloalkyl, aryl or hetaryl,
• e) 0.01 to 2% by weight of at least one crosslinking agent,
• f) 0 to 30% by weight of further monomers different from a) to e), the total of a) to f) adding up to 100% by weight.