| abstract |
Provided is a multilayer microporous membrane that has high permeability, heat resistance, excellent electrochemical stability, low heat shrinkage, and the like, and is particularly suitable for a battery separator. At least a first microporous membrane layer comprising a first polyethylene, a first polypropylene, and a second polypropylene different from the first polypropylene, and a second microporous membrane layer comprising the first polyethylene and the second polyethylene. A multilayer microporous membrane having a piercing strength of 3,500 mN or more and air permeability after heat compression of 1,000 seconds / cm 3 or less. [Selection figure] None |