POLYOLEFIN MICROPOROUS MEMBRANE AND METHOD FOR MANUFACTURING SAME, SEPARATOR FOR NONAQUEOUS-ELECTROLYTE SECONDARY CELL, AND NONAQUEOUS-ELECTROLYTE SECONDARY CELL

摘要

Provided is a microporous membrane having an excellent balance of temperature characteristics, shrinkage characteristics, permeability, and strength, and a separator for a nonaqueous-electrolyte secondary cell having high performance and excellent safety, and a nonaqueous-electrolyte secondary cell are thereby realized. A polyolefin microporous membrane characterized in that the difference between the shutdown shrinkage temperature and the maximum shrinkage temperature thereof in the TD direction measured by TMA is 7.2°C or greater, the difference between the shutdown shrinkage rate and the maximum shrinkage rate thereof in the TD direction is less than 25%, the piercing strength thereof when the membrane thickness is 16 µm is 400 gf or greater, and the ratio of the piercing strength and the air impermeability thereof when the membrane thickness is 16 µm is 2.0 to 4.0 (gf/(sec/100 cc)).