Thermoplastic moulding compounds of great toughness and good processability in the molten state

Claim 1

Thermoplastic moulding compositions comprising (A) from 5-90 parts by weight of one or more thermoplastic polymers of styrene, α-methylstyrene, styrene substituted in the nucleus, methyl methacrylate, acrylonitrile, methacrylonitrile, maleic acid anhydride, N-substituted maleimide, vinyl acetate, and mixtures thereof (B) from 5-90 parts by weight of one or more graft polymers of (B1) from 5-90 parts by weight of styrene, α-methylstyrene, styrene substituted in the nucleus, methylmethacrylate, acrylonitrile, methacrylonitrile, maleic acid anhydride, N-substituted maleimide, vinyl acetate or mixtures thereof on (B2) from 95-10 parts by weight of a rubber having a glass temperature ≧10° C. and (C) from 0.25-40 parts by weight of a block copolymer corresponding to the idealized formula (I) A-B-A; B-A-B or (A-B).sub.x (I) wherein x=1 to 40 and A denotes the residue of a homopolymer of styrene, vinyl naphthalene, butadiene or isoprene, and B denotes the residue of a homopolymer of a cyclic carbonate or lactone corresponding to the general formulae (II) to (IV): ##STR13## wherein R 1 , R 2 , R 3 and R 4 =H, C 1 -C 6 -alkyl, C 3 -C 6 -alkenyl, C 1 -C 6 -alkoxy or C 1 -C 6 -alkenoxy-C 1 -C 6 -alkyl, and m and n denote, independently of one another, 0, 1, 2, 3, 4, 5 or 6, ##STR14## wherein ##STR15## wherein ##STR16## the average molecular weights of blocks A and B being ≧800.