Claims
- 1. A method for improving a fluoropolymer-bonded asbestos diaphragm for use in a brine electrolysis cell, the improvement consisting essentially of incorporating into the diaphragm during the making thereof, about 5% to about 20% by weight of Na.sub.2 CO.sub.3.
- 2. The method of claim 1 wherein the fluoropolymer is at least one polymer or copolymer of tetrafluoroethylene, trifluoroethylene, vinylidene fluoride, vinyl fluoride, monochlorotrifluoroethylene, dichlorodifluoroethylene or fluorinated ethylene/propylene copolymer.
- 3. The method of claim 1 wherein the fluoropolymer is at least one of the group consisting of polyvinylidene fluoride, fluorinated ethylene/propylene copolymer and polytetrafluoroethylene.
- 4. The method of claim 1 wherein the asbestos is a mixture of chrysotile and crocidolite.
- 5. The method of claim 1 wherein the brine electrolysis cell is a chlor-alkali cell.
- 6. A method for preparing a polymer-bonded asbestos diaphragm for use in brine electrolysis, said method comprising,
- forming an aqueous slurry consistingly essentially of asbestos fibers, particulate polymer, and Na.sub.2 CO.sub.3,
- depositing onto a foraminous metal cathode a wet mat of the asbestos fibers, particulate polymer, and Na.sub.2 CO.sub.3,
- drying the so-formed mat to evaporate the water, leaving about 5% to about 20% by weight of Na.sub.2 CO.sub.3 dispersed in the mat, and
- heating the mat at a temperature sufficient to cause the polymer to bond the asbestos fibers into a coherent structure.
- 7. The method of claim 6 wherein the concentration of Na.sub.2 CO.sub.3 in aqueous solution is from about 50 to about 200 gpl.
- 8. The method of claim 6 wherein the concentration of Na.sub.2 CO.sub.3 in the bonded diaphragm is about 10% by weight.
- 9. The method of claim 6 wherein the depositing onto a foraminous metal cathode is done by vacuum deposition.
- 10. A composite cathode structure for use in brine electrolysis, said composite comprising
- a foraminous ferrous metal substrate having, on at least a portion of its surface,
- a fluoropolymer-bonded asbestos diaphragm which contains dispersed therein, about 5% to about 20% weight of Na.sub.2 CO.sub.3.
- 11. The composite of claim 10 for use in a chloralkali cell.
- 12. The composite of claim 10 wherein the foraminous substrate is a punched plate, woven wire mesh, or expanded sheet.
- 13. A method for brine electrolysis comprising passing a direct current through an aqueous NaCl electrolyte in an amount sufficient to electrolytically decompose the NaCl, said current being carried by the electrolyte through a Na.sub.2 CO.sub.3 -containing fluoropolymer-bonded asbestos diaphragm between anode and cathode, wherein the amount of Na.sub.2 CO.sub.3 is in the range of about 5% to about 20% by weight of the diaphragm.
Parent Case Info
This is a divisional of application Ser. No. 270,769, filed June 5, 1981 now U.S. Pat. No. 4,530,749.
US Referenced Citations (7)
Divisions (1)
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Number |
Date |
Country |
Parent |
270769 |
Jun 1981 |
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