GB718081A - Improvements in fuel pump diaphragms - Google Patents

Abstract

A coating composition, for application to cloth for making fuel pump diaphragms, comprises an aqueous dispersion of 2-chloro-1, 3-butadiene polymer modified by the addition of a copolymer of vinylidene chloride and acrylonitrile or vinyl chloride, or a mixture of these. The preferred coating consists of 60-85, preferably 70, parts 2-chloro-1, 3-butadiene polymer, 15-40 parts vinylidene chloride copolymer, preferably 30 parts of a composition containing 30 parts vinylidene chloride-acrylonitrile copolymer and 20 per cent. dibutyl phthalate plasticizer, 5-15 parts, preferably 10 parts, zinc oxide, and 1-30, preferably, 2 parts carbon black. The preferred coating dispersion is prepared as follows: 140 parts neoprene latex are stirred with solutions of polyoxyethylated fatty alcohol (5 parts) and sodium silicate (2.5 parts) stabilizers and dioctyl ester of sodium sulpho-succinic acid (1.4 parts). A masterbatch is prepared by mixing 10 per cent. ammoniacal casein solution containing sodium p-chloro-m-methyl phenate preservative (30 parts), 10 per cent. sodium salts of polymerized alkylarylsulphonic acids solution (30 parts) and 40 parts water, and then 65.2 parts zinc oxide, 13.05 parts carbon black, 4.36 parts thiocarbanilide acceleration, 4.36 parts sulphur, and 13.05 parts phenyl-b -naphthylamine are mixed in, and the whole milled together. The masterbatch is added to the neoprene latex mixture and a mixture of 56.6 parts vinylidene chloride-acrylonitrile latex, containing 20 per cent. dibutyl phthalate, which has had its pH adjusted to 8 by 5 per cent. caustic soda, and tetra-sodium salt of ethylene diamine tetra-acetic acid solution is added. The coating is vulcanized after drying.