Crystalline polymer microporous membrane and a method for producing the same, and a filtration filter using the crystalline polymer microporous membrane

摘要

A method for producing a crystalline polymer microporous membrane, which contains: placing a first crystalline polymer in a metal mold, and compressing the first crystalline polymer to form a first preforming body; placing a second crystalline polymer in a metal mold, and compressing the second crystalline polymer to form a second preforming body; extruding the first and second preforming bodies to form first and second extrusion bodies, respectively; rolling the first and second extrusion bodies to form first and second crystalline polymer films, respectively; heating a surface of the first crystalline polymer film or second crystalline polymer film, or both to perform asymmetric heating to give temperature gradient in a thickness direction thereof; drawing each of the first crystalline polymer film and the second crystalline polymer film; laminating the drawn first and second crystalline polymer films to form a laminate; and heating the laminate to perform heat setting.