| abstract |
The present invention has a strength and air permeability suitable for use in a filter material, a separator for an aqueous battery, a separator film for a battery, a separator film for an electrolytic capacitor, a breathable film, moisture permeability for paper diapers or house wraps, and other applications in the field of clothing, packaging and printing. The present invention relates to an excellent high molecular weight polyolefin microporous film and a method for producing the same, wherein the film is composed of a fiber consisting of stretched chain crystals and plate crystals and a fiber consisting of spiral crystals and / or spiral crystals. .n n n This high molecular weight polyolefin microporous film is obtained by heat-treating a polyolefin impermeable film having an intrinsic viscosity [η] of 3dl / g or more that does not substantially contain a plasticizer and / or a solvent by stretching and / or heat-setting as necessary. Manufacture. |