| 摘要 |
1,232,330. Graft polymerization process. DART INDUSTRIES Inc. 27 Aug., 1969 [27 Aug., 1968], No. 42619/69. Heading C3G. A process for preparing a graft polymer comprises (a) prepolymerizing in bulk a monomer or monomer mixture comprising from 100% to 60% by weight of at least one vinyl aromatic monomer and from 0% to 40% by weight of at least one alkenyl cyanide monomer to convert from 1% to 45 % by weight of the monomer(s) to polymer, (b) adding to the prepolymer resulting from step (a) from 0% to 40% by weight, based on the weight of the final graft polymer, of a diene rubber containing from 0% to 50% by weight of at least one vinyl aromatic monomer or a mixture of at least one vinyl aromatic monomer and at least one alkenyl cyanide monomer polymerized thereon, in the form of a latex having a majority of particles of size 0À005 to 1 micron, (c) suspending the resulting combination from step (b) in an aqueous solution of a suspending agent, (d) adding 0% to 40% by weight, based on the final weight of the graft polymer, of a diene rubber, as defined in step (b), in latex form to the aqueous solution, the sum of the quantity combined with the prepolymer in step (b) plus the quantity added in step (d) being sufficient to result in a final graft polymer containing at least 3% by weight of diene rubber, (e) substantially completely polymerizing the prepolymer in the presence of the diene rubber latex particles and an initiator and (f) recovering beads of the resulting graft polymer. Specified diene rubbers are natural rubber, polybutadiene, styrene-butadiene rubber and nitrile rubber. In the examples, a styrene-acrylonitrile prepolymer and a latex of polybutadiene, which has been pregrafted with styrene and acrylonitrile, are mixed, charged to a reactor containing an aqueous solution of hydroxyethyl cellulose and polymerized therein. Alternatively, the prepolymer is suspended in said aqueous solution, the latex is added and polymerization is completed. |
