| 摘要 |
Aqueous hydraulic fluids contain polymeric thickeners P with 95-100% by weight of one or more water-soluble monomers of the general formula I <IMAGE> in which R1 is hydrogen or a methyl group, X is -O- or -NR2, with R2 being hydrogen or an alkyl radical having 1 to 3 carbon atoms, Y is an alkylene group optionally substituted by C1-C3-alkyl radicals or hydroxyl groups and having 2 to 3 carbon atoms in the chain, and Z is a radical -SO3H, -NR3R4 or a radical <IMAGE> in which R3 and R4 and also R'3 and R'4 independently of one another are alkyl radicals having 1 to 4 carbon atoms or form with one another, if appropriate with inclusion of a further nitrogen or oxygen atom, a five-membered or six-membered heterocyclic ring, and with 0-5% by weight of monomers of the general formula II <IMAGE> in which R'1 is hydrogen or methyl and R5 is an alkyl radical having 6-18 carbon atoms, the polymers P having mean molecular masses M of between 50,000 and 300,000. |
