GB734390A - Improvements in and relating to methods of vulcanizing rubber - Google Patents

Abstract

Thin-walled vulcanized rubber products especially for electrical insulation purposes are made by incorporating vulcanizing ingredients in the rubber by means of a coagulated synthetic polymer latex or dispersion containing the vulcanizing ingredients by subjecting the latex or dispersion after coagulation and prior to incorporation in the main rubber stock to washing to remove materials interfering with the electrical properties of the final product and to obtain agglomeration of the coagulation particles to a desired size. Washing is preferably effected by diluting the latex with several times its volume of water or by washing the coagulum on a vibrating screen, the agglomeration being large enough to be retained on the screen. The latex may consist of polymers of isoprene, chloroprene, or isobutylene, or copolymers of butadiene with styrene, acrylonitrile, isoprene or isobutylene; and the main rubber stock may consist of the above polymeric materials or natural rubber.ALSO:Thin-walled vulcanized rubber products especially for electrical insulation purposes are made by incorporating vulcanizing ingredients in the rubber by means of a coagulated synthetic polymer latex or dispersion containing the vulcanizing ingredients, by subjecting the latex or dispersion after coagulation and prior to incorporation in the main rubber stock to washing to remove materials interfering with the electrical properties of the final product and to obtain agglomeration of the coagulation particles to a desired size. Washing is preferably effected by diluting the latex with several times its volume of water or by washing the coagulum on a vibrating screen the agglomeration being large enough to be retained on the screen. The latex may consist of polymers of isoprene, chloroprene, or isobutylene or copolymers of butadiene with styrene, acrylonitrile, isoprene or isobutylene; and the main rubber stock may consist of the above polymeric materials or natural rubber. In many examples, the synthetic latex and the main rubber stock contain ingredients chosen from the following:-Sulphur, tellurium, selenium, zinc oxide, litharge, zinc dimethyl dithiocarbamate, zinc diethyl dithiocarbamate, tretramethyl thiuram mono- and di-sulphide, tetraethyl thiuram disulphide, mercaptobenzthiazole, zinc mercaptobenzthiazole, benzothiazyl disulphide, bismuth dimethyl dithiocarbamate, zinc dimethyl dithiocarbamate, piperidine pentamethylene dithiocarbamate, diethyl ammonium diethyl dithiocarbamate, 2-mercaptobenzthiazoline, diphenyl guanidine, thiocarbanilide, sodium salts of polymerized alkaryl sulphonic acid, bentonite, kaolin, dimethylamine oleate, sodium chloride, calcium nitrate, ammonium oleate, naphthyl beta-mercaptam, air blown asphalt, coumarone indene resin, hydroquinone monobenzyl ether, zinc oxide, calcium carbonate, stearic acid, paraffin, salicylic acid, di-ortho-tolyl guanidine, carbon black, litharge, magnesium oxide, heptyl diphenylamine, petrolatum, p.p1. dibenzoylquinone dioxime, the reaction product of diphenylamine and acetone, symm. di-beta naphthyl paraphenylene diamine, and tris-(nonyl phenyl) phosphite.