Process for the preparation of copolymers

In a process for the manufacture of copolymers reacting in a first step an olefinically unsaturated dicarboxylic acid with a polyhydric alcohol to yield a hemi-ester having free hydroxyl groups, reacting said hemi-ester in a second step with a monoepoxy compound to yield an olefinically unsaturated diester containing hydroxyl groups and copolymerizing said diester with at least one unsaturated monomer having no free carboxyl groups, the improvement which comprises reacting the hemiester having no ether groups in a second step with an equivalent amount of a monoepoxide compound, based on the hydroxyl groups of the hemi-ester, selected from the group consisting of glycidol, a glycidylether of a phenol and glycidylester of saturated carboxylic acids at a temperature between 100.degree. and 170.degree. C. to yield a reaction product having a molecular weight between 250 and 1500 and an OH-number between 175 and 550 and then copolymerizing the diester having 2 hydroxyalkyl radicals at a temperature between 80.degree. and 220.degree. C. and wherein the hardenable reaction product thus obtained is either isolated or hardened with a hardening agent.