Vinyl chloride polymer composition modified for transparency, impact and thermal resistance

Claim 1

A thermoplastic vinyl chloride polymer composition comprising a blend of: I. 61 to 85 parts by weight of polyvinyl chloride and/or a copolymer comprised of no less than 80% by weight of vinyl chloride and no more than 20% by weight of at least one other copolymerizable monoethylenically unsaturated monomer, and; Ii. 15 to 39 parts by weight of a composite elastomer composition consisting essentially of: A. 20 to 60% by weight, based on the weight of the composite elastomer composition, of a graft copolymer consisting of (a) 15 to 45% by weight of graft monomers consisting of 30 to 70% by weight of methyl methacrylate and 30 to 70% by weight of styrene and (b) 55 to 85% by weight of a butadiene rubber, said graft copolymer being prepared by a sequential polymerization procedure of at least two stages, wherein during the first stage at least part of the methyl methacrylate is polymerized in the presence of a latex of said butadiene rubber, said butadiene rubber particles dispersed therein having an average particle size of 0.10 to 0.30 micron and a refractive index of 1.530 to 1.550 was determined at 20° C., and then, in a subsequent sequential stage or stages, which can be carried out in any order, the first polymerizate is separately polymerized with styrene and separately polymerized with the remainder of the methyl methacrylate, if any, and, B. 40 to 80% by weight, based on the weight of the composite elastomer composition, of a copolymer consisting of 35 to 65% by weight of α-methylstyrene, 10 to 60% by weight of methyl methacrylate, 5 to 35% by weight of acrylonitrile and 0 to 10% by weight of at least one other copolymerizable monoethylenically unsaturated monomer.