| 摘要 |
1,200,195. Suspension polymerization. TORAY INDUSTRIES Inc. 26 Sept., 1967 [26 Sept., 1966; 29 Sept., 1966], No. 43836/67. Headings C3G and C3P. Ethylenically unsaturated monomers are polymerized in suspension in an aqueous medium in the presence of a water-insoluble oil-soluble free radical-generating initiator and in the presence of, as suspending agent, at least one copolymer derived from at least 50% by weight of acrylamide and at least one C 1 -C 3 -alkyl ester of acrylic or methaorylic acid. The polymers obtained are in the form of pearly beads. Monomers specified are styrene, methyl acrylate, methyl methacrylate, styrene-acrylonitrile mixture, styrene-methyl methacrylate mixture, methyl methacrylate - ethyl acrylate mixture, styrene-divinylbenzene mixture and styrenemethyl methacrylate - acrylonitrile mixture; also exemplified is the suspension polymerization of styrene-acrylonitrile prepolymer in the presence of polybutadiene. Suitable initiators include benzoyl peroxide, lauroyl peroxide, dit.-butyl peroxide and azobisisobutyronitrile. If desired, a nonionic surfactant, e.g. a polyoxyethylene derivative of a phenol, fatty acid ester or amide, may be used conjointly with the specified suspending agent. Polymerization is suitably effected in the presence of a mercaptan chain transfer agent and preferably at a pH of 4 to 9. The suspending agent can be prepared by polymerizing acrylamide and the alkyl (meth)- acrylate ester(s) in a solvent such as water, a mixture of water and an alcohol (e.g. isopropyl alcohol), a mixture of water, acetone and an alcohol, or benzene in the presence of an initiator such as a persulphate or azobisisobutyronitrile. Some intramolecular cyclization and crosslinking may occur during the polymerization.
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