GB715618A - Improvements in or relating to rubber compositions - Google Patents

Abstract

Rubber compositions comprise vulcanized natural rubber or synthetic hydrocarbon rubber, e.g. a copolymer of butadiene with styrene in which butadiene predominates, reinforced with a hardened phenolic resin and intimately incorporated therewith a polymer or copolymer of a compound containing a vinyl group H2C:CH-, exemplified by polyvinyl butyral, chloride or acetate, polychloroprene, and a copolymer of vinyl chloride with vinyl acetate and/or vinylidene chloride. A hardenable phenolic resin, e.g. a Novolak-type phenolformaldehyde resin or a xylenol-formaldehyde resin, is incorporated with rubber, the resin is hardened e.g. by adding a methylene donor such as hexamethylene-tetramine or paraformaldehyde and heating, a vinyl polymer or copolymer is incorporated before or after hardening the resin, and the rubber is then vulcanized. Incorporation in the rubber of a vinyl polymer or copolymer not readily dispersible in rubber may be effected by mixing aqueous dispersions of rubber and the vinyl polymer or copolymer and co-precipitating by addition of a coagulant. The mix may contain sulphur, zinc oxide, stearic acid and mercaptobenzthiazole; a filler, e.g. calcium silicate or power station flue dust, and a pigment may be incorporated. The product may be used as leather substitutes or for battery cases, panels and door-knobs.ALSO:Rubber compositions comprise vulcanized natural or synthetic hydrocarbon rubber, e.g. a copolymer of butadiene with styrene in which the butadiene predominates, reinforced with a hardened phenolic resin and intimately incorporated therewith a polymer or copolymer of a compound containing a vinyl group. A hardenable phenolic resin, e.g. a Novolak-type phenol-formaldehyde resin or a xylenol-formaldehyde resin, is incorporated with rubber, the resin is hardened by adding a methylene donor such as hexamethylene-tetramine or paraformaldehyde and heating, a polymer or copolymer exemplified by polyvinyl butyral, chloride or acetate, a copolymer of vinyl chloride with vinyl acetate and/or vinylidene chloride, and polychlorophene is incorporated before or after hardening the resin, and the rubber is then vulcanized. Incorporation in the rubber of a vinyl polymer or copolymer not readily dispersible in rubber may be effected by mixing aqueous dispersions of the rubber and the vinyl polymer or copolymer and co-precipitating by addition of a coagulant. The mix may contain sulphur, zinc oxide, stearic acid and mercaptobenzthiazole; a filler, e.g. calcium silicate or power station flue dust, and a pigment may be incorporated.