Polymerisation process

摘要

Vinyl chloride is polymerized, either alone or with other copolymerizable monomers which do not contain a basic nitrogen atom, in an aqueous medium in which at least part of the polymerization takes place in the presence of at least 0,05 wt. per cent based on the monomer(s) of a quaternary ammonium compound of the general formula wherein R is a C5 or higher aliphatic hydrocarbon radical; R1 is -(CnH2nO)mH where n is 2, 3 or 4 and m is a positive integer; R11 is a C1-5 alkyl or hydroxyalkyl radical or R1; R111 is H or R11; X is an anion; and q is the valency of X. Several examples of radicals R, R1, R11 and R111 are given and examples of X are halide, sulphate, phosphate, borate, carbonate, nitrate, nitrite, cyanate, and acetate. Compounds mentioned are caprylylamidopropyl dimethyl b -hydroxyethyl ammonium bromide; lauramidopropyl methyl bis(b -hydroxyethyl) ammonium chloride; and stearamidopropyl dimethyl b -hydroxyethyl ammonium nitrate and phosphate. Comonomers specified are:- vinyl acetate; methyl methacrylate; methyl, ethyl and 2-ethyl-hexyl acrylates; methyl a -chloroacrylate; maleic and fumaric acids; diethyl maleate; diethyl and di-n-propyl fumarates; vinylidene chloride and acrylic acid. Catalysts mentioned for emulsion processes are peroxy compounds, e.g. hydrogen peroxide, which may be activated with a water-soluble Cu or Fe salt; per-esters, e.g. sodium peracetate; and alkali metal or ammonium persulphates which may be activated with a copper salt and a small partial pressure of oxygen as described in Specifications 589,264 and 598,777. The quaternary compound is preferably added stepwise or continuously both in emulsion and in dispersion processes. Catalysts specified for the latter are monomer soluble peroxides and hydroperoxides, e.g. benzoyl or lauroyl peroxide; t-butyl peroxy-benzoate; and azo compounds, e.g. a ,a 1 azo-bis-isobutyronitrile, diisopropyl 2,21-azo-bis-isobutyrate, and phenyl-azo-triphenylmethane. Anti-foam agents, e.g. silicones may be present. In Example 4 sodium formaldehyde sulphoxylate was mixed with that portion of the quaternary compound introduced during polymerization. The polymer may be spray- or tray-dried. The quaternary compound functions as emulsifying or dispersing agent during polymerization and gives antistatic properties to the product which may be used for moulding gramophone records. According to the Provisional Specification the vinyl chloride may be polymerized with any copolymerizable monomer, examples of such monomers including acrylonitrile.