Abstract: A vinyl chloride resin composition comprises:(1) 100 parts of vinyl chloride polymer; and(2) 0.1 to 30 parts of a polymer processing aid comprising:(A) 40 to 90 parts of a copolymer comprising80 to 100% of an alkyl methacrylate, and0 to 20% of a monomer copolymerizable therewith; and(B) 60 to 10 parts of a copolymer comprising20 to 79% of an alkyl methacrylate,20 to 79% of an aromatic vinyl monomer,1 to 49% of diolefin, and0 to 20% of a monomer copolymerizable therewith,the copolymers (A) and (B) having been wet-blended to provide 100 parts of the polymer processing aid, all quantities expressed in parts and percentages being by weight.

Abstract: A composition comprising polyvinyl chloride and a novel polymer processing aid is provided. The polymer processing aid can be obtained either by blending in latex form an alkyl methacrylate copolymer (A) and a copolymer (B) comprising as its essential constituents an alkyl methacrylate, a dialkyl itaconate or an alkyl acrylate, and a diolefin, or by copolymerizing one of the copolymers in the presence of the other copolymer.The polymer processing aid thus obtained improves the processability of the vinyl chloride resin composition with less reduction in impact strength.