Abstract: The invention relates to a copolymer for producing molded compounds or cast glass for the production of molded bodies having increased dimensional stability under heat, obtainable from the copolymerization of A) one or more ethylenically unsaturated ester compounds of the formula (I), where R1 is hydrogen or methyl and R2 a linear or branched alkyl group with 1 to 8 carbon atoms, B) one or more ethylenically unsaturated ester compounds of the formula (II), where R3 is hydrogen or methyl and R4 a cyclic group with 8 to 30 carbon atoms, C) one or more ethylenically unsaturated ester compounds of the formula (III), where R5 is hydrogen or methyl and R6 and R7, independently of each other, are hydrogen or a linear or branched group with 1 to 40 carbon atoms.