Aqueous outside release agent comprising diatomaceous earth and pyrogenic hydrophobic silica for molding and vulcanizing tires and other rubber articles

摘要

An aqueous outside release agent for the production of tires and other rubber articles is described, which contains 5 to 35% by wt. diatomaceous earth, 0.5 to 6% by wt. pyrogenic hydrophobic silica, 0.1 to 2% by wt. nonionic surfactant, 0.2 to 3% by wt. of a binder, 0.1 to 3% by wt. dye, 0 to 5% by wt. ethyl alcohol and the remainder water. Preferred binders are styrene-maleic acid or styrene-maleic anhydride copolymers and in particular ammonium salts thereof. Said outside release agent is used in processes for molding and vulcanizing tires and other rubber articles, it being sprayed onto the blank with the aid of air-atomizing guns before molding and vulcanization are carried out. A very good release effect is thereby achieved without vulcanization being impaired. As only very small quantities of outside release agent are needed, cleaning of the press mold and hence interruption of the production process are required very much less frequently than when conventional outside release agents are used.