Graft copolymers of alkyl methacrylates--alkyl acrylates onto diene-- alkyl acrylate copolymers and their use as impact modifiers

摘要

The impact resistance of resin compositions consisting of a thermoplastic polymer, particularly a homopolymer or copolymer of vinyl chloride can be improved by an impact additive of the graft copolymer type. The graft copolymer impact additive consists of a backbone composed of a statistical copolymer of butadiene or isoprene, an alkyl acrylate of a C.sub.2 to C.sub.12 alkyl, and optionally a polyfunctional cross- linking agent, onto which are grafted the chains of a statistical copolymer of an alkyl methacrylate of a C.sub.1 to C.sub.4 alkyl, particularly methyl methacrylate, and an alkyl acrylate of a C.sub.1 to C. sub.8 alkyl, particularly ethyl acrylate. The backbone of the graft copolymer impact additive comprises 0.5-35% by weight butadiene or isoprene, and up to 10 mole % of the cross-linking agent, while the graft chains of the graft copolymer comprise 5 to 50 mole % of the alkyl acrylate of a C.sub.1 to C.sub.8 alkyl, and the weight ratio between the grafted chains and the backbone can range from 10 to 200%.P PThe resin compositions are particularly useful to improve impact strength at low temperatures.