| 摘要 |
PURPOSE:To provide a perfluoro-based titled membrane suitable for electrolysis of alkali halide, constituted of, in the thickness direction, a layer in which both carboxylic acid and sulfonic acid groups exist, a second layer in which sulfonic acid group exists, and a third layer in which carboxylic acid group exists, in this order. CONSTITUTION:The objective membrane based on perfluoropolymer, constituted of the following three layers in this order in the thickness direction from anode side; (A) a layer in which both sulfonic acid and carboxylic acid groups exist with an exchange capacity totalling 0.5-1.5meq/g (on a dry resin basis) and the capacity of the sulfonic acid group (S) and that of the carboxylic acid one (C) satisfying the equation: 0.4<=S/ (C+S)<1, 0.1-20mu thick, (B) a second layer in which sulfonic acid group dominantly exists with an exchange capacity 0.5-1.2meq/g and 1-200mu thick, and (C) a third layer in which carboxylic acid group dominantly exists with an exchange capacity 0.5- 1.5meq/g and 1-100mu thick. Preferably, this polymer is made into of crosslinked structure either by incorporating crosslinking agent in the polymerization or by chemical and/or physical means after the film-formation. This membrane can be manufactured by laminating, e.g. through hot-pressing, three films corresponding to the above three layers (A), (B), and (C), respectively.
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