| 摘要 |
Graft copolymers are produced by polymerizing 20 to 66 parts by weight of a mixture of monomers containing 60 to 90% by weight of styrene and 40 to 10% by weight of acrylonitrile in a latex derived by the copolymerization of 40 to 75% by weight of butadiene and 60 to 25% by weight of styrene, with or without a minor proportion of a polyolefinic cross-linking agent, to yield a product having a swelling index (by a defined method) of not greater than 25. The resulting graft copolymers may be blended with separately prepared rigid styrene-acrylonitrile copolymers in such proportions that the blends contain 5 to 40% by weight of butadiene-styrene copolymer in graft copolymer form. The examples describe the polymerization of styrene-acrylonitrile mixtures in latices of butadiene-styrene and butadiene-styrene-divinyl benzene copolymers, using potassium persulphate as an initiator, and the use of the graft polymers so prepared in blends with styrene-acrylonitrile copolymers.
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