Hydrophilic, swellable graft polymers

Mixture of hydrophilic, swellable graft polymers obtained by reacting 0.5 to 50% by weight of a mixture of a polyalkylene oxide compound of the formula Ia ##STR20## or an alkali metal salt, ammonium salt or amine salt thereof and a compound of the formula IIa ##STR21## with 49 to 99% by weight of a radical of the formula IIIa ##STR22## or an alkali metal salt, ammonium salt or amine salt thereof and 0.1 to 2% by weight of a monomer containing at least two olefinically unsaturated double bonds and modifying it by application of carboxyl reactive compounds to its surface, where

• X.sup.1 is (C.sub.1 -C.sub.22)-alkyl, aryl, aralkyl, COCH.sub.3, CH.sub.2 COOR.sup.2, COCH.sub.2 CH.sub.2 COOH, COOR.sup.2, CH.sub.2 COCH.sub.2 COOR.sup.2, CO--CH.dbd.CH--COOH, ##STR23## or SO.sub.3 H Y.sup.1, is COCH.sub.3, CH.sub.2 COOR.sup.2, COCH.sub.2 CH.sub.2 COOH, CO--CH.dbd.CH--COOalkyl, CO--CH.dbd.CH--COOH, CH.sub.2 COCH.sub.2 COOR.sup.2, COOR.sup.2, SO.sub.3 H or ##STR24## n and m, independently of one another, are 2 to 300, R.sup.1 is hydrogen or methyl, R.sup.2, independently of one another, are hydrogen, methyl or ethyl, R.sup.3 is the carboxyl group, the sulphonyl group, the phosphonyl group, which is optionally esterified by means of alkanol having 1 to 4 carbon atoms, or a group of the formula ##STR25## in which R.sup.7 is the sulphonyl group or the phosphonyl group, and R.sup.4 is hydrogen, methyl, ethyl or the carboxyl group, are reacted under the conditions of gel polymerization.