Abstract: Thermoplastic molding compositions which contain(A) 50-99% by weight of a polyalkylene terephthalate and/or of a polycarbonate and(B) 1-50% by weight of an elastomeric polymer having epoxy and/or carboxyl groups on the surface,wherein component (B) is a graft polymer prepared by emulsion polymerization and has a glass transition temperature of below 0.degree. C. and a gel content of not less than 50%, have a high impact strength even at low temperatures.

Abstract: Impact-resistant thermoplastic polyester molding materials are prepared by thoroughly mixingA. from 52 to 99 parts by weight of a melt of one or more polyalkylene terephthalates withB. from 1 to 48 parts by weight of one or more elastomeric graft polymers prepared by emulsion polymerization and composed of1. from 70 to 90% by weight of a grafting base consisting of elastomeric polymers having a gel content of not less than 80% and a glass transition temperature Tg of less than -20.degree. C. and2. from 10 to 30% by weight of a grafted shell consisting of one or more polymers having a glass transition temperature Tg greater than 40.degree. C.,in the form of an aqueous dispersion in which not less than 80% of the particles of graft polymer B have a size of from 0.05 to 0.15 .mu.m, with simultaneous removal of the water which vaporizes.