| abstract |
The polyolefin microporous membrane of the present invention has a viscosity average molecular weight (Mv) of 2 million or more, a signal height of a first melting peak obtained from DSC (differential scanning calorimetry) of 3.0 mW / mg or more, and a specific surface area of 0.7 m 2 / g or more. 5 to 95% by weight of polyethylene (A) having an average particle diameter of 1 to 150 µm, and 95 to 5% by weight of polyethylene (B) having an Mw of greater than 10,000 to less than 200,000, wherein (A) and (B) The ratio of Mv ((A) / (B)) is 10 or more, the molecular weight of the whole film is 300,000 to 1.5 million, the fuse temperature of the film is 120 to 140 ° C, the rupture temperature is 150 ° C or more, and 140 ° C. The ratio of puncture strength to 25 ° C. puncture strength is 0.01 to 0.25. |