Thermoplastic moulding compositions with an improved heat distortion point

Claim 1

Thermoplastic mixtures containing: (A) 20-75 parts by weight of a thermoplastic aromatic polycarbonate, (B) 10-50 parts by weight of a graft polymer of: (B)(1) 5 to 90 parts by weight of a mixture of (B)(1)(1) and (B)(1)(2) wherein (B)(1)(1) is styrene, α-methyl styrene, nuclear-substituted styrene, methyl methacrylate or mixtures thereof and (B)(1)(2) is (meth)acrylonitrile, grafted onto (B)(2) 95 to 10 parts by weight of a rubber with a glass transition temperature TG≦10° C. (C) 10-70 parts by weight of a thermoplastic copolymer with a weight-average molecular weight of 15,000 to 200,000 as measured by light scattering or sedimentation and of 50-95% by weight of (C)(1) copolymerized with 50-5% by weight of (C)(2) wherein (C)(1) is styrene, α-methyl styrene, nuclear-substituted styrene, methyl methacrylate, or mixtures thereof, and (C)(2) is (meth)acrylonitrile, and (D) 0.5-5 parts by weight of a copolymer of 95-50% by weight of vinylaromatic compounds and 5-50% by weight of an ethylenically unsaturated nitrile compound, an ester of (meth)acrylic acid or a mixture of both, the copolymer having a weight average molecular weight of 2×10 6 to 1×10 7 as determined by gel chromatography or by the light scattering method.