GB361965A - Improvements in or relating to diaphragms permeable to the electric current - Google Patents

Abstract

A diaphragm permeable to the electric current is made by depositing natural or synthetic rubber, reclaimed rubber, guttapercha, balata, rubber isomers or the like from an aqueous dispersion thereof on a support and removing the deposit from the backing; the diaphragm is used in the undried state and in substantially the same condition as when deposited. The deposit may be made by immersion in latex of a form impregnated or coated with a substance giving rise to coagulating ions, e.g. a porous porcelain mould impregnated with acetic acid or calcium chloride solution. Alternatively the deposition may be effected by electrophoresis on a metallic anode or on a porous form impregnated with alkaline ammonium chloride. Latex in which the preserving ammonia has been reduced by aeration to a pH value of 9-9,5 may be employed. The diaphragms may be preserved by immersion in a slightly alkaline solution containing a preservative such as phenol. They may be mounted between perforated sheets of hard rubber or other insulating material or rubber-insulated woven wire fabrics or between bare metal supports.