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 C2 to C12 alkyl, and optionally a polyfunctional cross-linking agent, onto which are grafted the chains of a statistical copolymer of an alkyl methacrylate of a C1 to C4 alkyl, particularly methyl methacrylate, and an alkyl acrylate of a C1 to C8 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 C1 to C8 alkyl, and the weight ratio between the grafted chains and the backbone can range from 10 to 200%. The resin compositions are particularly useful to improve impact strength at low temperatures.