GB663756A - Improvements in or relating to the polymerization of chloroethylenes - Google Patents

Abstract

A latex-like aqueous dispersion of a polymer of a monomeric material comprising vinyl or vinylidene chloride is prepared by polymerizing the monomeric material in an aqueous medium in the absence of emulsifying or dispersing agents and in the presence of a compound capable of yielding sulphite ions in aqueous solution and a substance ionizable to yield copper ions. The monomeric material may comprise vinyl or vinylidene chloride either alone or in admixture with one another or with one or more other compounds copolymerizable therewith, such as ethyl, methyl or butyl acrylate, methyl methacrylate or ethacrylate, vinyl acetate, propionate, butyrate, bromide, fluoride or benzoate, vinyl pyridine, acrylonitrile, ethyl methylene malonate, styrene, dichlorostyrene, N-vinyl carbazole, N-vinyl pyrrolidone, vinyl isobutyl, methyl or ethyl ether, methyl, ethyl or isobutyl vinyl ketone, isobutylene or ethylene. The sulphite ion is preferably provided by sodium, potassium or ammonium sulphite and the copper ion may be provided by a water-soluble copper compound, preferably cupric sulphate, or by finely-divided metallic copper. An oxidizing agent of the type capable of oxidizing cuprous copper ion to the cupric state may be present, preferred oxidizing agents being potassium persulphate, dicrotonyl peroxide, di-(o,o1-dichlorobenzoyl) peroxide, dicaprylyl peroxide and ceric sulphate. The copper ion is preferably present in amount of 0.4 to 5 p.p.m., based on the monomer, the sulphite from 0.15 to 0.5 parts and the oxidizing agent from 0.2 to 1.5 parts per 100 parts of monomer. The reaction preferably takes place at a pH of 4.0 to 10.0, which may be controlled by buffer salts such as sodium bicarbonate and sodium metasilicate. Specifications 599,472 and 607,735 are referred to. The Specification as open to inspection under Sect. 91 relates also to polymerization in the presence of emulsifying agents such as sodium lauryl sulphate. This subject-matter does not appear in the Specification as accepted.