Abstract: A porous polyfluoroalkylene sheet, preferably of polytetrafluoroethylene, which is suitable for use as a stable low voltage separator or diaphragm in an electrolytic cell, such as one employed for the electrolysis of brine, without being subject to an objectionable voltage increase upon use, is of a thickness in the range of about 0.2 to 2 mm., a porosity in the range of about 70 to 90% and of pore sizes within a range up to about one mm. in diameter, with a pore size distribution such that the pores of a diameter about 0.1 micron (or less) are less than 10% of the total pore volume and the volume of those of about one to ten microns is a substantial part, e.g. 50%, of the total pore volume, and with the ratio of the numbers of such pores in the lower size range to those in the upper range being less than about 30. Limiting the 0.

Abstract: A porous polyfluoroalkylene sheet, very preferably of polytetrafluoroethylene, which is suitable for use as a separator in an electrolytic cell, such as one used for the electrolysis of brine, has a porosity in the range of 70 to 90%, a thickness in the range of 0.2 to 3.5 mm. and at least one of (a) an A X-ray ratio in the range of 0.1 to 0.35 and (b) a B X-ray ratio in the range of 0.75 to 0.98. Preferably the A X-ray ratio is in the range of 0.1 to 0.3, the B.sub.2 X-ray ratio is in the range of 0.75 to 0.98 and the B.sub.1 X-ray ratio is in the range of 0.1 to 0.32. The porous sheets are incorporated in separators or diaphragms for electrolytic cells and the uses of such separators and cells in electrolysis processes, preferably in the electrolysis of brine, are described. Also shown in the specification are a method for the manufacture of the porous sheets and a method for ascertaining which milled, sintered and leached porous sheets are more suitable for use in electrolytic processes.

Abstract: A porous polyfluoroalkylene sheet, preferably of polytetrafluoroethylene, which is suitable for use as a stable low voltage separator or diaphragm in an electrolytic cell, such as one employed for the electrolysis of brine, without being subject to an objectionable voltage increase upon use, is of a thickness in the range of about 0.2 to 2 mm., a porosity in the range of about 70 to 90% and of pore sizes within a range up to about one mm. in diameter, with a pore size distribution such that the pores of a diameter about 0.1 micron (or less) are less than 10% of the total pore volume and the volume of those of about one to ten microns is a substantial part, e.g. 50%, of the total pore volume, and with the ratio of the numbers of such pores in the lower size range to those in the upper range being less than about 30. Limiting the 0.

Abstract: A porous polyfluoroalkylene sheet, very preferably of polytetrafluoroethylene, which is suitable for use as a separator in an electrolytic cell, such as one used for the electrolysis of brine, has a porosity in the range of 70 to 90%, a thickness in the range of 0.2 to 3.5 mm. and at least one of (a) an A X-ray ratio in the range of 0.1 to 0.35 and (b) a B X-ray ratio in the range of 0.75 to 0.98. Preferably the A X-ray ratio is in the range of 0.1 to 0.3, the B.sub.2 X-ray ratio is in the range of 0.75 to 0.98 and the B.sub.1 X-ray ratio is in the range of 0.1 to 0.32. The porous sheets are separators or diaphragms for electrolytic cells and the uses of such separators and cells in electrolysis processes, preferably in the electrolysis of brine, are described. Also known in the specification are a method for the manufacture of the porous sheets and a method for ascertaining which milled, sintered and leached porous sheets are more suitable for use in electrolytic processes.

Abstract: Microporous membrane materials suitable for use in electrolytic cells, such as cells for the electrolysis of brine to produce chlorine, are formed from a mixture of polytetrafluoroethylene, a particulate pore forming material and an organic fluorinated lubricant. Such materials are preferably formed into a sheet, which is rolled to a desired thickness, sintered and subjected to leaching out of the pore forming material.

Abstract: A separator for an electrolytic cell or similar cell is made of a porous polymeric material, preferably porous polytetrafluoroethylene, and comprises a plurality of tubular portions of such material with one or two flange(s) at end(s) thereof for sealing to other such flanges and to the cell. The flanges are so constructed that when being sealed in place they do not strain or tear and do not strain or tear the material of the tubular portions. The separator is especially useful as a replacement for deposited asbestos diaphragms in electrolytic cells for the manufacture of chlorine and caustic.

Abstract: Hydrophobic polymeric separators are made wettable to electrolytic cell fluids by a post-manufacturing process of treating with fluorinated surface-active agents. The application of a hydrophilic film of fluorosurfactant onto separator surfaces followed by drying renders the separator permanently wettable. The hydrophilic surfaces rendered inert by drying are reactivated in-situ after installation of the separator by contacting the separator surfaces with heated aqueous solution. The pre-installation process provides a convenient means for shipping fully manufactured separators and for their storage by users until actually needed. From an operational standpoint, the pre-installation process eliminates fouling of the cell with foam occurring with conventional in-situ wetting procedures.

Abstract: The invention disclosed herein relates to a polymeric microporous electrolytic cell separators for producing alkali metal hydroxide at high current efficiencies, said separator having:a. porosity of at least about 60%;b. thickness of between 8 and 130 mils;c. hysteresis of from 0.30 to 0.99 wherein hysteresis is defined as the ratio of the amount of mercury trapped within the pore structure of the separator after release of pressure to 1 psi compared to the amount of mercury present when first subjected to total impregnation by mercury at 50,000 psi, andd. distribution of pore sizes in a range between 0.004 and 34 microns wherein at least 85% of said pores have a diameter of between 0.12 and 33 microns and at least 60% of said pores have a diameter between 0.

Abstract: Microporous membrane materials suitable for electrolytic cell utilization are formed from the blend of particulate polytetrafluoroethylene, a dry pore forming particulate material, and an organic lubricant. The materials are milled and formed into a sheet, which is rolled to the desired thickness, sintered, and subjected to leaching of the pore forming materials.