GB895153A - Process for the production of vinyl polymers - Google Patents

Abstract

A process for producing vinyl polymers comprises polymerizing finely dispersed vinyl chloride, vinyl acetate, acrylonitrile or mixtures thereof, optionally with a minor proportion of maleic anhydride, a maleic ester, vinyl pyridine, an acrylic ester or a methacrylic ester, at +20 to -50 DEG C. in an acid medium in the presence of trichloroethylene or an alkyl mercaptan as polymerization modifier, and, when the polymerization is carried out below about 5 DEG C., in an antifreeze medium comprising water and an alcohol, the polymerization being initiated by a catalyst comprising (a) hydrogen peroxide, an organic hydroperoxide, a persulphate or an organic peracid, (b) d-ascorbic acid, l-ascorbic acid or dihydroxy-maleic acid, and (c) a soluble salt of iron, chromium, cobalt, molybdenum, copper, tin, vanadium, silver or cerium. The medium may comprise methanol, ethanol, isopropanol, n-propanol, ethylene glycol or glycerol, Emulsifiers and suspending agents, e.g. sodium dodecylbenzene sulphonate, vinyl acetatemaleic anhydride copolymers, polyvinyl alcohol and cellulose derivatives, may be present. Specified catalyst components include (a) potassium persulphate and cumene hydroperoxide and (c) ferrous sulphate, ferrous ammonium sulphate, ferrous glyconate, ferric gluconate, cupric sulphate, cerous nitrate and ceric nitrate. The copolymerization of vinyl chloride with acrylonitrile, maleic anhydride, methyl acrylate and 4-vinyl pyridine sulphate (Example VII) and the saponification of a polyvinyl acetate to polyvinyl alcohol in the presence of methanol and sulphuric acid (Example III) are described.