MULTILAYERED MICROPOROUS POLYOLEFIN FILM

摘要

The present invention provides a polyolefin multilayer microporous membrane comprising: at least first microporous layers which form both surface layers and at least a second microporous layer disposed between the both surface layers, wherein the static friction coefficient of one of the surface layers of said polyolefin multilayer microporous membrane against the other surface layer in longitudinal direction (MD) is 1.1 or less, and wherein the pore density calculated from the average pore radius measured by mercury porosimetry method and the porosity, according to the formula below is 4 or more: Pore density = P / A 3 × 10 4
wherein A represents the average pore radius (nm) measured by mercury porosimetry method and P represents the porosity (%);
which polyolefin multilayer microporous membrane having good slip characteristics between membranes and a fine dense microporous structure; and a method for producing the same.