The invention relates to a polymer obtainable by the radical polymerization of at least one monomer, namely one or more (meth)acrylate monomers and optionally, in addition, vinylic comonomers, wherein the polymer has a molar mass MW of at least 5,000 g/mol and at most 200,000 g/mol and at least one of the monomers is functionalized with at least one epoxy group, wherein the proportion of the epoxide-functionalized monomer(s) (a) is more than 30 wt %.