| 摘要 |
Disclosed is a polyolefin microporous membrane having a thickness of not less than 1 mum and not more than 50 mum, a porosity of not less than 30% and not more than 70%, a puncture strength in terms of a 1 mum thick film of not less than 0.15 N/mum, a tensile strength in the machine direction (MD tensile strength) of not less than 30 MPa, a tensile strength in the transverse direction (TD tensile strength) of not less than 30 MPa, a thermal shrinkage at 65°C in the transverse direction (TD thermal shrinkage) of not more than 1%, and a ratio between the thermal shrinkage at 65°C in the machine direction and the thermal shrinkage at 65°C in the transverse direction (MD thermal shrinkage/TD thermal shrinkage) of more than 2. Also disclosed are a method for producing such a polyolefin microporous membrane and a nonaqueous electrolyte secondary battery using such a polyolefin microporous membrane. |
