HIGHLY POROUS SEPARATOR FOIL

摘要

The invention relates to a biaxially oriented single- or multilayer porous foil, the porosity of which is generated by transformation of ß-crystalline polypropylene during orientation of the foil. The Gurley value of the foil is < 250 s. The invention also relates to a process for producing the foil by using a low transverse stretching velocity for the transverse orientation process.