GB727578A - Improvements in or relating to plastic materials - Google Patents

Abstract

An emulsion produced by the emulsion polymerization of aliphatic conjugated diolefins or their copolymers is mixed with a solvent for the elastomer, an emulsion breaking salt added, the emulsion broken, the resulting elastomer dissolving in the solvent, a hydrogenation catalyst is added and the elastomer hydrogenated and recovered. Specified diene polymers and copolymers are polybutadiene, polypentadiene, polymethylpentadiene and the copolymers butadiene-styrene, butadiene-isoprene, butadiene-methylacrylate, butadieneethyl acrylate and isoprene-styrene, while specified solvents are methylcyclohexane, cyclohexane, benzene, toluene, isooctanes, isoheptanes, n-heptanes and dioxane. Mixtures of solvents may be used. Emulsion breaking salts specified are barium, calcium and sodium chloride, water-soluble sulphates, nitrates and metal salts of lower molecular weight fatty acids. The synthetic rubber-solvent phase is preferably dehydrated, e.g. with bauxite and alumina, before the addition of the hydroquatin catalyst which may be nickel-kieselguhr, Raney nickel, copper chromite, molybdenum sulphide, platinum oxide, copper chromium oxide and finely-divided platinum and palladium in amount from 2 to 20 weight per cent of the elastomer. Preferred hydrogenation temperatures are 200-300 DEG F., preferably at pressures of 100 to 1000 p.s.i.g., for a period preferably of 2 to 7 hours. Preferred solutions for hydrogenation are those containing about 50 grams of a 25 to 40 Mooney viscosity elastomer per litre of solvent.