Molding compositions for optically readable information-storage media

Claim 1

A copolymer, adaptable to use as a molding composition for making optically readable data storage media, said copolymer being free of aromatic groups and comprising (A) from 20 to 70 percent by weight of at least one ester of the formula ##STR9## wherein R 1 is derived from an alcohol, R 1 OH, which is cyclohexanol, an alkyl-substituted cyclohexanol wherein each alkyl has up to 12 carbon atoms, a cyclohexylalkanol, or a bicyclic or tricyclic alcohol, with the proviso that a homopolymer of such an ester have a Vicat softening temperature (in conformity with DIN 53460) above 80° C.; (B) from 10 to 60 percent by weight of at least one ester of the formula ##STR10## wherein R 2 is hydrogen or methyl and R 3 is a linear or branched aliphatic group having from 2 to 22 carbon atoms, with the proviso that a homopolymer of such an ester have a Vicat softening temperature (in conformity with DIN 53460) below 90° C.; (C) from 20 to 40 percent by weight of methyl methacrylate; and (D) from 0 to 20 percent of at least one aprotic monomer having a polar group X, of the formula ##STR11## wherein R 4 is hydrogen or methyl and X is --CN or --Y--A--Z, wherein Y is ##STR12## wherein R 5 is alkyl having from 1 to 6 atoms, A is a hydrocarbon chain having from 1 to 8 carbon atoms, and Z is ##STR13## wherein R 6 is (C 1 -C 3 )-alkyl or phenyl, or wherein A--Z is ##STR14##