| 摘要 |
A graft copolymer is produced by preparing a stable emulsion comprising (a) an elastomer, (b) a solvent for the elastomer of one or more ethylenically unsaturated monomers present in an amount greater than the elastomer, (c) a normally thermoplastic polymer of monomer(s) (b) and, based on the total weight of (a), (b) and (c), 0.05 to 10% of a stabilizer which is a block or graft copolymer of monomer(s) (b) and at least one monomer of the elastomer, and polymerizing monomer(s) (b). The proportions of (a), (b) and (c) are such that the solution of (a) in monomer(s) (b) forms the discontinuous phase while the solution of polymer (c) in monomer(s) (b) forms the continuous phase. Monomer(s) (b) is an alkenyl aromatic hydrocarbon or a nuclearly substituted halogen derivative thereof, or a mixture of one of these with methyl methacrylate, acrylonitrile and/or alpha-methyl styrene, or methyl methacrylate alone. When (b) is styrene, (c) is e.g. polystyrene or a copolymer of styrene and methyl methacrylate or acrylonitrile. When (a) is polybutadiene and (b) is styrene, the stabilizer may be a graft polymer of styrene or polybutadiene or of butadiene or polystyrene, or of styrene or butadiene on a block copolymer of these monomers, or said block copolymer per se. The emulsions are polymerized in bulk or by dispersion in an aqueous medium. In Examples 1 and 2 polybutadiene and polystyrene are dissolved in styrene and a graft copolymer of styrene or polybutadiene is added thereto; the resulting emulsion is polymerized in bulk or in an aqueous medium containing di-tert.-butyl peroxide, 2,6-di-ter.-butyl-4-methyl phenol and sodium carboxymethyl methyl cellulose. In Example 3 a graft copolymer of styrene on a butadiene-styrene copolymer is used. A graft copolymer of acrylonitrile and styrene on an acrylonitrile-butadiene copolymer is added in Example 4 to a solution of a butadiene-acrylonitrile elastomer and a styrene-acrylonitrile copolymer in a mixture of styrene and acrylonitrile. The graft coplymer used in Example 5 is of methyl methacrylate on polybutadiene, (a) is polybutadiene, (b) is methyl methacrylate and (c) is polymethyl methacrylate. In Example 6 the graft copolymer is of styrene and methyl methacrylate on polybutadiene, (a) is polybutadiene, (b) is styrene and methyl methacrylate and (c) is a styrene-methyl methacrylate copolymer. A block copolymer of styrene and butadiene is used in Example 7 in which (a) is polybutadiene, (b) is styrene and (c) is polystyrene.
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