| 摘要 |
PROBLEM TO BE SOLVED: To provide a microporous membrane especially suitable for a battery separator having, for example, high permeability, heat resistance, excellent electrochemical stability and low heat shrinkage degree.SOLUTION: A microporous membrane at least includes: a first microporous membrane layer containing a first polyethylene, a first polypropylene, and a second polypropylene different from the first polypropylene; and a second microporous membrane layer including the first polyethylene and a second polyethylene. The microporous membrane has a piercing strength of 3,500 mN or more and air permeability of 1,000 s/cmor less after thermal compression. |
