MICROPOROUS MEMBRANE MADE FROM POLYOLEFIN

摘要

Disclosed is a microporous membrane made from a polyolefin wherein the thickness is 1-30 µm, the porosity is 30-60%, the air permeability is 50-250 sec/100 cc, the puncture strength is 3.5-20.0 N/20 µm, the maximum pore diameter determined by a bubble point method is 0.08-0.20 µm, and the ratio between the maximum pore diameter and the average pore diameter (maximum pore diameter/average pore diameter) is 1.00-1.40. Since this microporous membrane made from a polyolefin is highly safe while maintaining a high permeability, it is useful especially as a separator for recent small-sized, high-capacity nonaqueous electrolyte batteries.