NOVEL METHOD FOR POLYMERIZING A VINYL COMPOUND IN THE PRESENCE OF A CARBON DIOXIDE MEDIUM

1,172,713. Polymerization process. SUMITOMO CHEMICAL CO. Ltd. 19 May, 1967 [19 May, 1966], No. 23412/67. Heading C3P. A vinyl or vinylidene compound is polymerized by the action of a catalyst or ionizing radiation while in the presence of liquid carbon dioxide or carbon dioxide dissolved in the monomer under pressure at- 78‹ to 100‹ C. The catalyst, which may be added in solution in a hydrocarbon or ether, may be a peroxide, azo compound, Friedel-Crafts catalyst (especially for ethers) or an organoaluminium compound which may be mixed with a titanium halide. Suitable radiations are X-rays, γ-rays, or neutron rays applied externally or #- or α-rays internally at a rate of 104-106 roentgens per hour. The polymer produced is usually insoluble in the carbon dioxide or is precipitated with methanol and is recovered by reducing the pressure to remove the carbon dioxide. Examples refer to the polymerization of vinyl chloride, styrene, styrene-methyl methacrylate, acrylonitrile, acrylic acid, vinyl chloride-vinyl acetate, vinyl acetate and ethyl vinyl ether.