Wetting of diaphragms
AssigneeE. I. Du Pont de Nemours and Company
InventorShoibal Banerjee
Life of this patent
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Abstract
A diaphragm for electrolyzing alkali metal chloride solutions is provided which is one or more layers of a porous support, coated with a perfluoro ion exchange polymer and then wet with a wetting solution which has a surface tension of 22 to 45 dynes/cm. The wetting solution is preferably an aqueous alcohol and most preferably aqueous 3-6.5% butanol. The wetting solution assists in initial water penetration into the pores of the diaphragm, rendering the diaphragm hydrophilic so as to resist gas locking and premature shutdown of the electrolytic cell.
Claims23
An article comprising (a) a diaphragm which is used for electrolyzing alkali metal chloride solutions, (b) said diaphragm having at least a portion of its exterior surfaces and a portion of its interior pores coated with a perfluoro ion exchange polymer or a solution comprising said perfluoro ion exchange polymer and a solvent or dispersant for said polymer and (c) said diaphragm has been coated with a wetting agent which has a surface tension of about 22 to 45 dynes/cm, wherein said wetting agent is different than said solvent or dispersant, if any.
A process for preparing a diaphragm for use in electrolyzing metal chloride solutions comprising wetting said diaphragm, said diaphragm having at least a portion of its exterior surfaces and a portion of its interior pores coated with a perfluoro ion exchange polymer or a solution comprising said perfluoro ion exchange polymer and a solvent or dispersant for said polymer, with a wetting agent which has a surface tension of about 22 to 45 dyne/cm, said wetting agent is applied to the diaphragm after the perfluoro ion exchange polymer or said solution.
An electrolytic cell comprising anode and cathode compartments, separated by a diaphragm, in which at least a portion of its exterior surfaces and a portion of its interior pores of said diaphragm have been coated with a perfluoro ion exchange polymer or a solution comprising said perfluoro ion exchange polymer and a solvent or dispersant for said polymer and the diaphragm is coated with a wetting agent which has a surface tension of about 22 to 45 dynes/cm, wherein said wetting agent is different than said solvent or dispersant, if any.
Dependencies are inferred from the claim text.