摘要:
The invention relates to water-soluble or water-swellable polymers, containing a) 25-35 mol.% of one or more recurrent structural units of formula (1), where • R 1 and R 2 represent hydrogen, methyl oder ethyl, • A represents a linear or branched C 1 -C 12 -alkylene, and • Q + stands for H + , NH 4 + , Li + , Na + , K + , ½ Ca ++, ½ Mg ++ , ½ Zn ++ , ⅓ Al +++ , or organic ammonium ions of the formula [HNR 5 R 6 R 7 ]+, b) 3 to 8 mol.% of one or more recurrent structural units of formula (2), where • R 1 represents hydrogen, methyl oder ethyl , • X + stands for H + , NH 4 + , Li + , Na + , K + , ½ Ca ++ , ½ Mg ++ , ½ Zn ++, ⅓ Al +++ , or organic ammonium ions of the formula [HNR 5 R 6 R 7 ]+, • B is a linear or branched alkylene group with 1 to 6 carbon atoms and • n is a whole number between 0 and 5, and c) 57 to 72 mol.% of a (meth)acrylamide.