Abstract: An electrolytic diaphragm cell for the production of halogen, hydrogen and an alkali metal hydroxide solution by electrolysis of an aqueous alkali metal halide solution, the cell comprising a plurality of anodes vertically mounted on the base of the cell, a cathode box providing cathodes between adjacent anodes, and a hydraulically permeable diaphragm between adjacent anodes and cathodes comprising one or more sheets of a porous non-melt-processable fluorine-containing polymer joined into the form of an endless-belt by a strip or strips of melt-processable fluorine-containing polymer fused into the sheet or sheets at or near juxtaposed edges of the sheet or sheets, the diaphragms being connected to upper and lower slotted supports of a melt-processable fluorine-containing polymer by means of strips of a melt-processable fluorine-containing polymer bonded to the supports at or near the slots therein and fused to the upper and lower edges of the diaphragm.

Abstract: An electrolytic diaphragm cell for the production of halogen, hydrogen and an alkali metal hydroxide solution by electrolysis of an aqueous alkali metal halide solution, the cell comprising a plurality of anodes vertically mounted at one side of the cell, a cathode box mounted at the opposite facing side of the cell providing cathodes between adjacent anodes, and a hydraulically permeable diaphragm between adjacent anodes and cathodes, comprising a sheet of a porous non-melt-processable fluorine-containing polymer connected to an upper and lower slotted supports of a melt-processable fluorine-containing polymer by means of strips of a melt-processable fluorine-containing polymer fused to the upper and lower edges of the diaphragm. The diaphragm preferably comprises a plurality of sheets of the non-melt-processable fluorine-containing polymer which are joined together by joining strips of melt-processable fluorine-containing polymer fused into the sheets at or near juxtaposed edges of the sheets.

Abstract: A process for the manufacture of a porous diaphragm of a synthetic material, especially polytetrafluoroethylene, which comprises forming a sheet of the synthetic material in admixture with a solid particulate additive (eg starch) to be removed therefrom, introducing said sheet into a cell, and removing the solid particulate additive from the sheet by treating the sheet in situ in the cell with an acid (eg hydrochloric acid) containing a corrosion inhibitor (eg propargyl alcohol). The porous diaphragms are especially suitable for use in diaphragm cells for the production of chlorine from sodium chloride brine.