| 摘要 |
An alkaline battery separator made of a porous film which consists substantially of a polyolefin having a weight average molecular weight of less than 300,000 and a number average molecular weight of 15,000 or more and which has a thickness of 0.025 to 1 mm, a porosity of 50 to 80%, an average pore diameter of 0.05 to 0.5 mu and an average ratio of the larger dimension to the smaller dimension of the pore opening of not more than 2. The alkaline battery separator has not only an extremely low electrical resistance and a high alkali resistance but also a transmission-inhibitive ability for the active materials of battery and is excellent in mechanical strength and flexibility. It does not show appreciable shrinkage by heat. For producing such an alkaline battery separator, 10 to 50 volume percent of a polyolefin, 7 to 42 volume percent of an inorganic filler and 30 to 75 volume percent of an organic liquid having a solubility parameter of from 8.6 to 9.9 inclusive are blended, the amount of the polyolefin being 2/3 to 9 multiple of the amount of the inorganic filler, and the resulting blend is subjected to melt-molding to form a film, followed by extraction of the organic liquid and the inorganic filler from the film. In the extraction of the organic liquid and the inorganic filler, the film does not undergo shrinkage to provide a separator having excellent characteristics.
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