Method of preparing reinforced asbestos diaphragms for chlorine-caustic cells

摘要

A resin modified asbestos diaphragm is prepared by diluting a heat curable polyvinylidene fluoride homopolymer resin latex containing no more than about 5% resin solids with an aqueous solution containing about 4% to 5% sodium hydroxide. From about 6 to about 11 parts of asbestos fibers are then slowly added to this alkaline resin latex solution for each part of resin solids contained therein with agitation to produce a clear aqueous slurry of resin coated asbestos fibers. To this slurry is then added an aqueous solution of 10% to 15% sodium hydroxide to swell the asbestos fibers. The resulting slurry is deposited on a screen to form a diaphragm which is carefully dried and cured at elevated temperatures to complete the polymerization of the polyvinylidene fluoride resin and form a bonded resin coated asbestos fiber product that is dimensionally stable. Such resin modified asbestos diaphragms may be used in electrolytic cells for electrolyzing alkali metal halide solutions.