Polyolefin microporous membrane, rechargeable battery separator, and rechargeable battery

摘要

The subject of the present invention is that not only the shutdown temperature of the microporous membrane is low, but also the membrane strength at the shutdown temperature is excellent, and the polyolefin microporous that imparts excellent shutdown characteristics and high safety when used as a separator for a secondary battery A film is provided, and as a solution, a polyolefin microporous film having a shutdown temperature of 135 ° C. or lower and a crystal melting rate of 50% or less at the shutdown temperature is provided.