GB1085410A - Improvements in the bonding of synthetic textile fibres to rubber - Google Patents

Abstract

A composition suitable for use in bonding synthetic textile fibres to rubber comprises an aqueous dispersion or emulsion of a masked isocyanate which upon heating generates free isocyanate groups, an epoxy resin, a rubber latex and a protective colloid. Suitable masked isocyanates are phenol-blocked metaphenylene diisocyanate, phenol-blocked triphenyl methane triisocyanate and phenol-blocked methylene-bis-(-4-phenylisocyanate), and the epoxy resin may be epoxidized polybutadiene or the reaction product of bis-phenol A and epichlorhydrin. The rubber latex may be a natural rubber latex or a synthetic rubber, e.g. a copolymer of butadiene with a vinyl compound such as styrene or vinyl pyridine, an oil-extended copolymer of butadiene and styrene, a terpolymer of butadiene, styrene and vinyl pyridine, cis-1,4-polybutadiene, polychloroprene and copolymers of butadiene and acrylonitrile and the protective colloid may be a polyether ester, a polyvinyl ether or an ammoniacal casein solution. The aqueous dispersion or emulsion may have a solids content of 10-25% by weight. The dispersion or emulsion may be prepared by mixing the masked isocyanate, epoxy resin, latex, protective colloid and water together in the presence of an emulsifying agent, e.g. soaps, alkyl aryl sulphonates and polyether alcohols. The dispersion or emulsion may also contain 10-25% by weight of paraformaldehyde based on the weight of the dry masked isocyanate.ALSO:Improved bonding of synthetic textile fibres, e.g. polyester, polyamide and viscose rayon fibres, used to reinforce rubber compositions to rubber is obtained by coating the fibres by passing them through an aqueous dispersion or emulsion of a masked isocyanate which upon heating generates free isocyanate groups, an epoxy resin, a rubber latex and a protective colloid. Suitable masked isocyanates are phenol-blocked metaphenylene diisocyanate, phenol-blocked triphenyl methane triisocyanate and phenol-blocked methylenebis(-4-phenylisocyanate), and the epoxy resin may be epoxidized polybutadiene or the reaction product of bis-phenol A and epichlorhydrin. The rubber latex may be a natural rubber latex or a synthetic rubber, e.g. a copolymer of butadiene with a vinyl compound such as styrene or vinyl pyridine, an oil extended copolymer of butadiene and styrene, a terpolymer of butadiene, styrene and vinyl pyridine, cis-1,4-poly-butadiene, polychloroprene and copolymers of butadiene and acrylonitrile and the protective colloid may be a polyether ester, a polyvinyl ether or an ammoniacal casein solution. The aqueous dispersion or emulsion may have a solids content of 10-25% by weight. If the textile fibre is in the form of a monofilament the dispersion preferably contains the masked isocyanate and rubber latex in a ratio of 8.5:1 and if the textile fibre is in the form of a cord the ratio may be 0.3:1. The ratio of the weight of the masked isocyanate to the weight of the latex may however vary from 10:1 to 0.2:1. The proportion of the epoxy resin may be equal to or less than the amount of the masked isocyanate. The dispersion or emulsion may contain 4-10% of the dry colloid based on the total weight of the dry masked isocyanate and dry epoxy resin. The dispersion or emulsion may be prepared by mixing the masked isocyanate, epoxy resin, latex, protective colloid and water together in the presence of an emulsifying agent, e.g. soaps, alkyl aryl sulphonates and polyether alcohols. The dispersion or emulsion may also contain 10-25% by weight of paraformaldehyde based on the weight of the dry masked isocyanate. The fibres may be treated at room temperature or higher temperatures and then dried. They may then be provided with a thin coating of a rubber composition, made up into articles, e.g. tyres, driving and conveyer belts, hose, turpaulins, containers for solids or liquids, or life rafts. The fibres may be treated in the form of weftless cord fabrics.