GB523208A - Improvements in or relating to the coagulation of aqueous dispersions - Google Patents

Abstract

523,208. Synthetic rubber. DU PONT DE NEMOURS & CO., E. I. Dec. 28, 1938, No. 37661. Convention date, Dec. 24, 1937. [Class 2 (iii)] Synthetic rubber dispersions produced by the emulsion polymerization of butadiene, diaethyl butadiene, isoprene, 2-chloro- and 2 bromo-butadiene and 2-chloro- and 2-bromomethyl-butadiene are coagulated by means of the combined action of a water-soluble salt and a water-soluble alcohol, aldehyde, ketone or carboxylic acid. In examples (1) 2-chloro-1-3- butadiene is polymerized in emulsion with cetyl trimethylammonium bromide and sulphur dioxide, phenyl-#-naphthylamine in benzene is added and coagulation is effected with aqueous butyl or ethyl alcohol and sodium chloride ; (2) an emulsion of butadiene, methacrylic nitrile, oleamidomethyl dimethylamine hydrochloride and acetic acid is polymerized and the diluted dispersion is coagulated with aqueous butyl alcohol and sodium chloride. Other emulsifying agents may be used such as N-cetyl and C-cetyl betaine, sulphonic acids made by hydrolysis of the reaction products of sulphuric dioxide and a halogen on a long-chain non- aromatic hydrocarbon, and aromatic compounds obtained by condensing sulphonic acids with formaldehyde. For the coagulation the sodium chloride may be replaced by sodium fluoride, sulphate, carbonate, or acetate, potassium iodide, ammonium chloride or calcium chloride or salts containing both organic and inorganic radicles ; other alcohols that may be used include #-ethoxyethyl alcohol, 4-hydroxy-2 chloro-2-butene, diacetone alcohol and isobutyl hexyl and benzyl alcohols ; the alcohols should have a solubility of at least 1 per cent. at the temperature employed.