Use of modified water-soluble polymer as a crosslinking aid

The invention relates to the use of modified water-soluble polymers as a crosslinking agent, characterized in that the modified water-soluble polymers are obtainable by free radical polymerization of a) one or more ethylenically unsaturated monomers which carry one or more epoxy, amine, carboxylic acid, carboxylic anhydride and / or silane groups, and b) one or more, different from the monomers a) ethylenically unsaturated monomers in the presence of 25 to 80 wt .-% of one or more water soluble polymers, based on the total weight of the modified water-soluble polymers.