GB723898A - Methods of compounding rubber - Google Patents

Abstract

A synthetic rubber is reinforced by adding a reaction product of humic acid and a methylene donor and dispersing a polymeric compound therein. Rubbers specified are polybutadiene and copolymers of butadiene with isobutylene, acrylonitrile or styrene and the polymeric compound may be polyvinyl acetate, butyral or p chloride, polychloroprene and copolymers of vinyl chloride with vinyl acetate or vinylidene chloride. The methylene donor is preferably hexamethylene tetramine although paraformaldehyde may also be used. The compositions may be obtained by coagulation of aqueous dispersions of rubber, polymer and alkaline salt of humic acid followed by milling and then heating with the methylene donor. Carbon black may also be included. The products which may be vulcanized in the usual manner are useful for soling footwear, making suitcases, battery cases, control panels and door knobs. Specifications 702,670 and 713,531 are referred to.ALSO:Natural or synthetic rubber which is a polymer of an unsubstituted conjugated diene hydrocarbon or a copolymer of an unsubstituted conjugated diene hydrocarbon with a compound copolymerizable therewith is reinforced by adding a reaction product of humic acid and a methylene donor and dispersing a polymeric compound which is a polymer of a monomer containing the group CH2= 1/c - cl as a sole unsaturated group or a copolymer thereof with a compound copolymerizable therewith or a polymer of a diene hydrocarbon containing a CH2= 1/c - cl group or a polyvinyl acetal or polyvinyl acetate therein. The methylene donor is preferably hexamethylene tetramine although polymers of formaldehyde such as paraformaldehyde may be employed in the presence of an alkaline catalyst. The rubber may be unvulcanized natural rubber, or polybutadiene, isobutylene-butadiene copolymers, butadiene-acrylonitrile copolymers or butadiene-styrene copolymers. The polymeric compound may be polyvinyl acetate, polyvinyl butyral, polyvinyl chloride or copolymers of vinyl chloride with vinyl acetate or vinylidene chloride or polymers of substituted polychloroprene. In an Example, natural rubber latex is mixed with humic acid in caustic soda polyvinyl chloride latex added, and then the mixture precipitated with hydrochloric acid. Hexamethylene tetramine is added, and then a vulcanizing mix consisting of sulphur, zinc oxide, stearic acid, mercaptobenzthiazole, and calcium silicate added and the mix vulcanized at 153 DEG C. Specifications 702,670 and 713,531 are referred to.