Procédé de préparation d'une composition de polymères greffés et utilisation de ladite composition

1355861 Multi-stage graft polymers; PVC compositions ROHM & HASA CO 9 July 1971 [17 July 1970] 32298/71 Heading C3G and C3P A process for making an emulsion comprises the steps, (A) forming a non-rubbery, hard first stage polymer by emulsion polymerization of a first monomer charge of 50-100 wt. per cent of non-cross-linking vinylaromatic monomer and 50-0 wt. per cent of monovinylidene monomer copolymerizable therewith (other than vinylaromatic monomer) in the presence of 0-10 wt. per cent of a polyfunctional cross-linking monomer based on the weight of the first monomer charge; (B) adding to the resulting non-rubbery, hard polymer stage produced in step (A) a second monomer charge of 50-100 wt. per cent of one or more of butadiene, isoprene, chloroprene and C 3 -C 8 alkyl acrylate monomer and 50-0 wt. per cent of monovinylidene monomer copolymerizable therewith (other than butadiene, isoprene, chloroprene of C 3 -C 8 alkyl acrylate monomer) and 0-10 wt. per cent of polyfunctional cross-linking monomer based on the weight of the second monomer charge and emulsion polymerizing the second monomer charge to form a rubbery polymer stage substantially entangled on and/or within the hard polymer stage produced in step (A) and (C) adding to the polymer resulting from steps (A) and (B), a third monomer charge of 50-100 wt. per cent of a C 1 -C 4 alkyl methacrylate and 50-0 wt. per cent of a monovinylidene monomer copolymerizable therewith (other than C 1 -C 4 alkyl methacrylate) and, based on the weight of the third monomer charge 0-10 wt. per cent of polyfunctional cross-linking agent and 0-1À0 wt. per cent of an alkyl mercaptan (C 3 -C 12 ), and emulsion polymerizing the third monomer charge to form a third stage polymer substantially entangled on and/or within the polymer produced in steps (A) and (B). The polymerization may be initiated by either free radical or redox catalysts. The examples refer to graft polymers prepared by aqueous emulsion polymerization in which the 1st stage monomers are a mixture of styrene and diallyl maleate; the second stage monomers are a mixture of (a) butyl acrylate and butylene acrylate, or (b) butyl acrylate and diallyl moleate; and the 3rd stage monomer is methyl methacrylate. The graft polymer may be blended with a vinyl halide polymer containing more than 50% by weight vinyl halide mers. Numerous examples of such vinyl halide polymers are given and the examples describe blends of the graft polymer with polyvinyl chloride, the