Improvements in or relating to the production of rubber articles from dispersions ofor containing natural rubber latex

摘要

Aqueous dispersions of rubber or rubber substitutes, which have been heated to relatively high temperatures such as 140 DEG C. and upwards in order to render them viscous or adhesive, are obtained with the aid of emulsifying-agents such as soap. The dispersion may be made by mixing the treated rubber or rubber substitute while warm with a water-soluble soap in pasty condition and thereafter mixing with further quantities of water. If desired, the rubber may be mixed with an aqueous medium under such conditions that a water-soluble soap is formed in situ. The rubber may be coagulated rubber, vulcanized rubber, synthetic rubber, waste, reclaim, or rubber substitute such as factice made by vulcanization, oxidation or polymerization of oils such as rape oil. The dispersions may contain compounding, vulcanizing, or anti-ageing ingredients. In an example, brown rubber substitute of the sulphur vulcanized vegetable oil type is mixed with cotton seed oil and heated to 155 DEG C. until, on cooling, it is just fluid. It is mixed with soap and dispersed in water. The soap used may be ammonium oleate and ammonia solution may be added with stirring until a uniform emulsion results. In another example ground dark rubber substitute of the sulphur vulcanized vegetable oil type is heated with cotton seed oil until a thick red oily product is obtained. This is dispersed in a paste of ammonium oleate obtained by adding strong ammonia solution to oleic acid. Specifications 219,635, 290,313, and 302,201, [all in Class 70, Indiarubber &c], are referred to.ALSO:Articles produced from natural rubber latex by spreading, impregnating, spraying, moulding, extrusion, dipping, electrophoresis, or other method are coated with an artificially prepared aqueous dispersion of rubber or rubber substitute which has been previously heated to a relatively high temperature such as 140 DEG C. and upwards so as to reduce it to a viscous and preferably adhesive condition. The dispersion of the treated rubber may be mixed with natural rubber latex before being applied to the rubber articles. Alternatively, rubber articles may be made directly from mixtures of the treated rubber dispersion and rubber latex. Adhesive properties are thus conferred on surfaces obtained by evaporation of rubber latex and the assembly of plies of rubber latex proofed fabric and the production of a farina finish on rubber-latex proofed material for raincoats are facilitated. Before heating the rubber to a high temperature it may be subjected to mastication. The dispersion may be made by mixing the treated rubber while warm with a water-soluble soap in pasty condition and thereafter mixing with further quantities of water. If desired the treated rubber may be mixed with an aqueous medium under such conditions that a water-soluble soap is formed in situ. The rubber may be heated to a high temperature alone or in the presence of a high boiling point liquid such as a high boiling petroleum or oleic or stearic acid. Instead of natural rubber latex, natural latices of guttapercha, balata, and similar vegetable resins may be used. The rubber which is to be heated to a high temperature may be coagulated rubber, vulcanized rubber, synthetic rubber, waste, reclaim, or rubber substitute such as factice, made by vulcanization, oxidation or polymerization of oils such as rape oil. The dispersions may contain compounding, vulcanizing, or anti-ageing ingredients. In an example, smoked sheet rubber is heated in an open vessel in an oven at 190 DEG C. until it becomes very viscous and adhesive. It is mixed with mineral oil, oleic acid and petroleum and the mixture is emulsified with an aqueous solution of casein gum acacia, and ammonia. The emulsion is mixed with concentrated rubber latex. In another example, pale crepe rubber is cold masticated and then heated with mineral oil until viscous. It is dispersed by stirring into a paste of ammonium oleate. The dispersion is mixed with water and then with concentrated latex. In another example, brown rubber substitute of the sulphur-vulcanized vegetable oil type is mixed with cotton seed oil and heated until on cooling it is just fluid. It is mixed with a soap such as ammonium oleate, dilute ammonia water being added with stirring until a uniform emulsion results. In another example a dark sulphur-vulcanized vegetable oil is heated with cotton seed oil and the red oily product is dispersed with ammonium oleate paste made by the addition of strong ammonia solution to oleic acid. Specifications 219,635, 290,313, and 302,201, [all in Class 70, Indiarubber &c.], are referred to. The Provisional Specifications state that the aqueous dispersions of rubber or rubber substitute with adhesive properties obtained by heating, may be mixed with bitumen dispersions, and that benzoic acid may be added to the rubber during mastication.