Copolymer containing oxazoline monomers and use thereof as cross-linking agent

The present invention relates to novel copolymers and methods for producing same, wherein the copolymers contain the following as building blocks: a C1 -20 alkyl (meth)acrylate and/or C8-20 vinyl aromatic (monomer a); a monoethylenically unsaturated, hydrophilic monomer comprising at least one sulfonic acid group (-SO3M) (monomer b); and a monoethylenically unsaturated monomer comprising at least one oxazoline group (monomer c); and wherein the fraction of monomers a) and b) in total is less than 50 wt%, with respect to the total amount of monomers in copolymer A.