US Patent 7728073 Thermoplastic moulding compounds exhibiting improved chemical resistance

The present invention relates to thermoplastic molding compositions comprising a mixture of(A) from 30 to 69% by weight, based on the sum of components (A), (B) and (C), of a methyl methacrylate polymer,(B) from 30 to 69% by weight, based on the sum of components (A), (B) and (C), of a copolymer obtainable by polymerizing a styrenic monomer and a vinyl cyanide, and(C) from 1 to 40% by weight, based on the sum of components (A), (B) and (C), of a graft copolymer obtainable from(C1) from 60 to 90% by weight, based on (C), of a core obtainable by polymerizing a 1,3-diene and a styrenic monomer,(C2) from 5 to 20% by weight, based on (C), of a first graft shell, and(C3) from 5 to 20% by weight, based on (C), of a second graft shell composed of an alkyl (meth)acrylate polymer,with the proviso that the ratio of (C2) to (C3) is in the range from 2:1 to 1:2.