GB1482061A - Process for removing monomers from an aqueous dispersion of a vinyl chloride homopolymer or copolymer - Google Patents

Abstract

1482061 Removing monomer from vinyl chloride polymer dispersions HOECHST AG 6 Nov 1975 [16 Nov 1974] 46049/75 Heading C3P A process for removing a monomer from an aqueous dispersion of a vinyl chloride polymer comprises: (a) admixing the aqueous dispersion of the polymer with a cationic, anionic or non- ionic surfactant, the surfactant being monomercompatible and being used in a proportion of 0À01-1% by weight based on the solid matter of the dispersion; (b) heating the dispersion to a temperature ranging from the freezing point of the polymer up to 120‹ C. and allowing the dispersion to remain at that temperature for 1 to 4 hours; and (c) continuously drawing off the gaseous matter issuing from the aqueous dispersion. The polymer may be polyvinyl chloride or vinyl chloride copolymers, e.g. copolymers of vinyl chloride with vinyl acetate, butadiene, butyl acrylate or methyl methacrylate. Suitable surfactants are (a) the alkali metal salts of fatty acids, the alkali metal or amine salts of fatty alcohol sulphates or sulphonates; (b) resinic soaps; (c) high molecular weight amine or quaternary ammonium salts; and (d) alkylarylpolyglycol ethers. The heating in step (b) may be effected directly by introducing steam into the dispersion and/or indirectly by means of an external heating source. The monomer is preferably expelled at atmospheric pressure and within the same temperature range as specified in step (b). In the specific examples an aqueous polyvinyl chloride suspension is mixed with sodium lauryl sulphate. After 4 hours the residual monomer content is 0 or 2 p.p.m.