| 摘要 |
PURPOSE:To lower electrolytic voltage and improve current efficiency by beforehand subjecting the anode side layer of a fluorine-contg. cation exchange membrane to swelling treatment by leaving the thin layer on the cathode side then using the same for electrolysis of an aqueous alkali chloride soln. CONSTITUTION:An ion exchange membrane of 20-600mum film thickness comprising a two-element copolymer of at least the fluorovinyl compound shown in the formula I [e.g.; CF2=CFO(CF2)3COOCH3] and the fluorinated olefin (e.g.; CF2= CF2) shown by the formula II is prepared. Next, the ion exchange group precursor of this ion exchange membrane is hydrolyzed by using an aqueous caustic alkali soln. or the like by leaving preferably 10-100mu thickness. Next, in succession to this hydrolysis, the membrane is subjected to swelling in an aqueous medium. The swollen surface of the thus resulted fluorine-contg. cation exchange membrane is installed by being faced the anode side and an aqueous alkali chloride soln. (e.g.; NaCl) is electrolyzed. As a result, alkali hydroxyde of a high concentration of, e.g., >=40% may be produced at high current efficiency. |
