POLYOLEFIN MICROPOROUS FILM, AND COATING BACKING MATERIAL PRODUCED USING POLYOLEFIN MICROPOROUS FILM

摘要

Provided is a microporous film which can be used suitably as a coating backing material that has been highly demanded in fields including separators for batteries, films for capacitors and filters, and which can be coated uniformly. A polyolefin microporous film characterized in that the relative value of an average value of peak pore diameters as determined in the TD direction relative to the standard deviation of an expected value of pore diameters as determined in the TD direction is less than 24%. The polyolefin microporous film has a narrow pore diameter distribution as determined in the TD direction and also has dense pore diameters. Therefore, the non-uniformity in coating with a coating material and the wrinkling of a coating can be reduced drastically in the polyolefin microporous film, and therefore the polyolefin microporous film can be used suitably as a coating backing material.