| abstract |
In the present invention, the peak temperature of tan δ of dynamic viscoelasticity measured at a frequency of 1 Hz, a temperature increase rate of 5° C./min, and a strain rate of 0.1%/sec is 105 in at least one of the MD direction (machine direction) and TD direction (width direction). It relates to a porous polyolefin film of not less than °C. The porous polyolefin film of the present invention is not easily short-circuited due to foreign matter even if it is thinned, and is also excellent in shape stability against high temperature and high tension. |