| 摘要 |
PROBLEM TO BE SOLVED: To obtain an ion-exchange membrane which hardly suffers the release of ion-exchange resin from the surface and has low electrical resistance and low rate of permeability to water by laminating two or more ion exchanger layers containing an ion-exchange resin and a binder and each having an ion- exchange resin content different from one another. SOLUTION: It is desirable to mix the ion-exchange resin and the binder at a weight ratio of (40:60) to (75:25). The ratio of the ion-exchange resin content of the ion exchanger layer having lower ion-exchange resin content to that of the layer having higher ion-exchange resin content is preferably at most 0.95:1, and the ratio of the thickness of the former layer to that of the latter layer is preferably (1:1) to (1:50). It is desirable that the thickness of the heterogeneous ion-exchange membrane is 10-2,000 μm, the ion-exchange capacity of the ion-exchange resin is 1.0-5.0 meq/g dry resin, and the largest particle diameter of particles is at most 100 μm. Examples of the binder used include polyolefins and olefin thermoplastic elastomers. |
