METHOD FOR MANUFACTURING SEPARATOR OF PP-PE COMPOSITE STRUCTURE BY UNIDIRECTIONALLY STRETCHING BY INFLATION FILM METHOD

摘要

PROBLEM TO BE SOLVED: To disclose a method for manufacturing a separator of a PP-PE composite structure by unidirectionally stretching by an inflation film method.SOLUTION: A method for manufacturing a separator of a PP-PE composite structure comprises a base film preparation step, a thermal treatment step, a cold drawing step, a hot drawing step and a setting step in this order. A microporous film manufactured according to the invention is arranged to utilize characteristics, such as a low self-closing temperature of PE and a high film collapse temperature of PP, and it has a pore closing temperature of 128-133°C, and a film collapse temperature of 168-180°C. A PE microporous film melts between 120 and 130°C. The microporous film serves to suppress the rise in temperature accompanying the closing of micropores because of its early closing property, and suits characteristics of a lithium ion battery.SELECTED DRAWING: None