GB634503A - Improvements in or relating to emulsion polymerization - Google Patents

Abstract

In the emulsion polymerization of a mixture of 40 to 100 per cent of a diolefin and 0 to 60 per cent of a mono-olefinic monomer, the monomers are dispersed in water with a catalyst and 0.1 to 1.5 per cent of a "soap," the dispersion is heated with agitation until a latex containing more than 5 per cent solids is obtained, more soap is added in one or more increments or continuously and polymerization continued to produce a concentrated latex of large particle size. The "soaps" are emulsion stabilizers having a hydrophilic alkali metal or ammonium radical and a hydrophilic organic radical. They may be formed in situ. Specified are salts of rosin acids, e.g. pimeric, sapinic, colophonic, abietic and abietinic acids such as sodium abietate and potassium rosinate; of fatty acids, e.g. stearic, beheric, margaric, arachidic, palmitic, myristic, oleic and lauric acids such as sodium, potassium and ammonium oleates; of sulphonic acids, e.g. sodium naphthalene sulphonate; sulphates, e.g. sodium lauryl sulphate; sulphonated ethers R-O-RySO2-OX, esters R-COORySO2-OX, and amides RC-NH-RySO2-OX, where R and Ry are aliphatic monovalent and divalent hydrocarbon radicals respectively and X is alkali metal or ammonium. Also included are neutralized alkylamines, e.g. dodecylamine hydrochloride and substituted alkylamine esters of fatty acids such as diethyl-ethanolamine oleate. Diolefins specified are butadiene-1,3, isoprene and other alkyl-substituted butadienes and the co-monomers may be styrene, acrylonitrile, methacrylonitrile, methyl acrylate, methacrylate and a -chloracrylate, 2,3-dichloro-styrene and vinyl pyridine. Suitable catalysts are potassium persulphate and potassium ferricyanide. The emulsions may contain also n-or tert.-dodecyl mercaptan, trisodium phosphate, and inert hydrocarbons, and the sodium salts of polymerized alkyl naphthalene sulphonic acids. In an example: (2) a butadiene emulsion is heated at 125 DEG F. for 12.5 hours to obtain 20 per cent solids content, when an aqueous solution of sodium hydroxide and a solution of stearic acid in warm styrene are added. After 43.5 hours an aqueous solution of potassium oleate is added and polymerization continued to 59 per cent solids content.