| 摘要 |
1,239,670. Grafted ethylene-vinyl acetate copolymers. LEUNA-WERKE " WALTER ULBRICHT " VEB. 8 May, 1969, No. 23602/69. Heading C3G. A grafted ethylene-vinyl acetate copolymer is prepared by a process in which the reaction mixture produced in the copolymerization of ethylene with vinyl acetate at 50‹ to 300‹ C. and a pressure above 500 atmospheres is crosslinked, immediately after completion of the copolymerization and separation of unconverted monomers, whilst stirring at 50‹ to 200‹ C. and a pressure of from 1 to 50 atmospheres in the presence of free radicals, the mixture then being heated to 50‹ to 200‹ C. at 1 to 50 atmospheres with stirring and grafted with an ethylenically unsaturated monomer. Specified graft monomers are vinyl chloride, vinyl acetate, styrene, acrylic and methacrylic acids and esters thereof, and acrylonitrile. In the examples, the ethylenevinyl acetate copolymer is (a) cross-linked with cumene hydroperoxide prior to being grafted with vinyl acetate, acrylic acid or vinyl chloride, (b) cross-linked with dilauroyl peroxide prior to being grafted with styrene, (c) cross-linked without an additional source of free radicals, prior to being grafted with acrylonitrile and (d) cross-linked with di-tert.-butyl peroxide prior to being grafted with ethyl methacrylate. |
