GB1025291A - Modified polyvinyl chloride compositions - Google Patents

Abstract

Compositions comprise (A) 70 to 90 weight per cent of a vinyl chloride homopolymer or copolymer with up to 15 weight per cent of an ethylenically unsaturated comonomer and (B) 10 to 30 weight per cent of a modifier copolymer of a mixture of (C) 30 to 50 weight per cent of a conjugated diolefin and at least one monoethylenically unsaturated vinylidene monomer selected from (D) alkenyl aromatic compounds in amount of 10 to 45 weight per cent and (E) C1- 4 alkyl acrylates and methacrylates in amount of 15 to 55 weight per cent, together with (F) 6 to 12 weight per cent of acrylonitrile or methacrylonitrile, the amount of (F) being expressed as a percentage of (C), (D), (E) and (F) and each of (C), (D) and (E) being expressed as a total of (C), (D) and (E). Vinyl chloride copolymers specified are those with vinyl acetate, butyrate, stearate and benzoate, dialkyl fumarates, dialkyl maleates and vinylidene chloride. (C) may be butadiene, isoprene or chloroprene, and (D) may be styrene, a -methylstyrene, vinyltoluene or p-chlorostyrene. The compositions may be prepared by copolymerizing the monomers (C) to (F) in an aqueous dispersion of the vinyl chloride polymer in the presence of catalysts, e.g. benzoyl peroxide, lauroyl peroxide and azodiisobutyronitrile, and chain transfer agents, e.g. dodecyl mercaptan and dibromodicholoroethane. The compositions may be compounded with plasticizers, e.g. dioctyl phthalate and tricresyl phosphate; stabilizers, e.g. tin maleate, dibutyl tin dilaurate, dibutyl tin-S,S1-bis-(3,5,5-trimethylhexyl mercaptoacetate) and barium/cadmium stearate; pigments; fillers; lubricants; mould release agents and antioxidants; and may be moulded to form shaped articles. Examples describe compositions of polyvinyl chloride and copolymers of (1), (2), (3) and (7) butadiene, methyl methacrylate and acrylonitrile, with and without a -methyl styrene; (4) isoprene, styrene, methyl methacrylate and acrylonitrile; (5) butadiene, ethyl acrylate and acrylonitrile, with and without a -methylstyrene; and (6) butadiene, methyl methacrylate and acrylonitrile together with styrene, t.-butylstyrene, o-vinyltoluene, o-chlorostyrene and p-chlorostyrene.