GB841215A - New thermoplastic moulding compositions - Google Patents

Abstract

Thermoplastic moulding compositions comprise 100 parts by weight of a copolymer of styrene, acrylonitrile and methyl methacrylate containing 20 to 50% by weight of combined styrene, 20 to 50% by weight of combined acrylonitrile and 10 to 50% by weight of combined methyl methacrylate, and 10 to 70 parts by weight of a rubbery polymer or copolymer of butadiene-1,3. Specified copolymers are those of butadiene with styrene, acrylonitrile, methacrylonitrile and methyl methacrylate, optionally together with a small amount of a cross-linking agent, e.g. divinyl benzene or glycol dimethacrylate. The styrene copolymer may be prepared by polymerization (1) in aqueous emulsion in the presence of emulsifying agents, e.g. sodium lauryl sulphate, sodium oleyl sulphate, sodium cetyl sulphate, the sodium salts of sulphonated castor oil, sulphonated and sulphated methyl oleate, sodium oleate, sodium palmitate and sodium stearate, water-soluble catalysts, e.g. hydrogen peroxide, potassium persulphate and redox systems, and modifiers, e.g. organic polysulphides and dialkyl xanthogen disulphides; (2) in suspension in the presence of granulating agents, e.g. gelatin, pectin, starch, methyl cellulose, hydroxyethyl cellulose, talc, kaolin, polyvinyl alcohol and salts of polyacrylic and polymethacrylic acids, and monomer soluble catalysts, e.g. benzoyl peroxide; or (3) in solution or mass. The rubbery polymers may be prepared in aqueous emulsion. The polymers may be mixed by mixing latices prior to spray drying or coagulation, by adding one in dry powder form to a dispersion of the other, or by masticating both in dry form, e.g. in a Banbury or on heated rolls. Pigments, fillers and lubricants may be added. The compositions may be vulcanized and may be used to form pipes, pipe couplings, refrigerator parts, kick panels, protective helmets, wheels, gears, pulleys and combs. Specification 804,956 is referred to.