Polymer composition comprising, based on the weight of the polymer composition, the following components A, B and C: A. 40.0 to 84.0 wt.-%, preferably 54.0 to 78.0 wt.-% of a copolymer comprising alkyl(meth)acrylates, aromatic vinyl monomer and unsaturated carboxylic acid anhydride; B. 4.0 to 20.0 wt.-%, preferably 6.0 to 10.0 wt.-% of a copolymer comprising aromatic vinyl monomer and a vinyl cyanide monomer, wherein the copolymer B is a copolymer of 68.0 to 85.0 wt.-% of the aromatic vinyl monomer; and 15.0 to 32.0 wt.-%, of the vinyl cyanide monomer, based on the weight of the copolymer B; and C. 12.0 to 40.0 wt.-%, preferably 16.0 to 36.0 wt.-% of a particulate core-shell type graft copolymer comprising a butadiene-based core as a rubbery phase and a copolymer comprising alkyl(meth)acrylates and, optionally, aromatic vinyl monomer as a hard phase; wherein the particulate core-shell type graft copolymer C comprises: a butadiene-based core comprising at least 65.0 wt.-% polybutadiene, based on the weight of the butadiene-based core; and a shell comprising 60.0 to 100.0 wt.-% of alkyl(meth)acrylates and 0.0 to 40.0 wt.-% of the aromatic vinyl monomer, based on the weight of the shell; wherein the components A and B form a polymer matrix and the particulate core-shell type graft copolymer C is dispersed in said polymer matrix; and the content of the vinyl cyanide monomer in the particulate core-shell type graft copolymer C is not higher than 5.0 wt.-%, preferably not higher than 2.0 wt.-%, more preferably not higher than 0.5 wt.-%, based on the weight of the core-shell type graft copolymer C. A. 40.0 to 84.0 wt.-%, preferably 54.0 to 78.0 wt.-% of a copolymer comprising alkyl(meth)acrylates, aromatic vinyl monomer and unsaturated carboxylic acid anhydride; B. 4.0 to 20.0 wt.-%, preferably 6.0 to 10.0 wt.-% of a copolymer comprising aromatic vinyl monomer and a vinyl cyanide monomer, wherein the copolymer B is a copolymer of 68.0 to 85.0 wt.-% of the aromatic vinyl monomer; and 15.0 to 32.0 wt.-%, of the vinyl cyanide monomer, based on the weight of the copolymer B; and C. 12.0 to 40.0 wt.-%, preferably 16.0 to 36.0 wt.-% of a particulate core-shell type graft copolymer comprising a butadiene-based core as a rubbery phase and a copolymer comprising alkyl(meth)acrylates and, optionally, aromatic vinyl monomer as a hard phase; wherein the particulate core-shell type graft copolymer C comprises: a butadiene-based core comprising at least 65.0 wt.-% polybutadiene, based on the weight of the butadiene-based core; and a shell comprising 60.0 to 100.0 wt.-% of alkyl(meth)acrylates and 0.0 to 40.0 wt.-% of the aromatic vinyl monomer, based on the weight of the shell; wherein the components A and B form a polymer matrix and the particulate core-shell type graft copolymer C is dispersed in said polymer matrix; and the content of the vinyl cyanide monomer in the particulate core-shell type graft copolymer C is not higher than 5.0 wt.-%, preferably not higher than 2.0 wt.-%, more preferably not higher than 0.5 wt.-%, based on the weight of the core-shell type graft copolymer C. a butadiene-based core comprising at least 65.0 wt.-% polybutadiene, based on the weight of the butadiene-based core; and a shell comprising 60.0 to 100.0 wt.-% of alkyl(meth)acrylates and 0.0 to 40.0 wt.-% of the aromatic vinyl monomer, based on the weight of the shell; wherein the components A and B form a polymer matrix and the particulate core-shell type graft copolymer C is dispersed in said polymer matrix; and the content of the vinyl cyanide monomer in the particulate core-shell type graft copolymer C is not higher than 5.0 wt.-%, preferably not higher than 2.0 wt.-%, more preferably not higher than 0.5 wt.-%, based on the weight of the core-shell type graft copolymer C.