Process for the preparation of asbestos-free microporous electroconductive substrate

Process for the preparation of an asbestos-free microporous electroconductive substrate. The process includes (a) providing an aqueous suspension of a mixture of carbon or graphite fibers, polytetrafluoroethylene fibers, inert mineral fibers, at least one fluorinated polymer, a silica porogen, and, optionally, at least one thickening agent; (b) depositing a coating onto a porous support by programmedly vacuum filtering said suspension therethrough, the coating comprising a liquid medium; (c) removing the liquid medium from said coating and then drying same; (d) sintering the coating thus formed; and (e) extracting the silica porogen therefrom. A substrate including intimate admixture of carbon or graphite fibers, polytetrafluoroethylene fibers and inert mineral fibers, and optionally, at least one thickening agent, consolidated by a binding amount of at least one fluorinated polymer is formed. The substrate produced is well suited for the electrolysis of solutions of, e.g., alkali metal halides.