| 摘要 |
PROBLEM TO BE SOLVED: To provide a porous film having excellent resistance rising performance and heat resistance and being excellent in satety.SOLUTION: A porous film has at least one layer composed of a resin composition containing 80 mass% of a polypropylene, wherein a secondary battery is fabricated using the porous film as a separator. In the electric resistance measured while the temperature is raised at a rate of 2°C/min, a temperature (T1) at which the resistance value becomes 10 times the resistance value at 50°C is ≥100°C and <120°C; a temperature rising amount from a temperature at which the resistance value exceeds 10 times to a temperature at which the resistance value exceeds 1,000 times is ≥10°C; a temperature (T2) at which the resistance value becomes 1,000 times is ≥120°C and <150°C; and a temperature (T3) at which the resistance value becomes ≤0.1 &OHgr; is ≥170°C. |
