| 摘要 |
PURPOSE:To obtain a diaphragm having a good chemical resistance, a small ion transmission resistance, a small electric resistance and an excellent mechanical strength by subjecting a microporous film consisting of a polyfluoroolefin to alkali metal treatment, then irradiating ionizing radiation upon the film before hydrophilic monomers are subjected to graft polymerization. CONSTITUTION:A microporous polyfluoroolefin film preferably a polytetrafluoroethylene film is subjected to alkali metal treatment so as to introduce active polar groups which can easily produce cross-linking radicals onto the surface of the film. When an untreated film is used, radicals of an amount necessary for graft polymerization are produced by the irradiation of ionizing radiation of such a low dose as not to cause graft polymerization, thereby effectively graft- polymerizing the monomers to make the film hydrophilic. The thus obtained microporous film has excellent chemical stabilities especially a good alkali resistance. Moreover, it has a small electric resistance and a high selective permeability for ions. Therefore the microporous film can be used as a superior diaphragm for an alkaline battery. |
