METHOD FOR PRODUCING MICROPOROUS MEMBRANE OR MICROPOROUS STRETCHED FILM, AND MICROPOROUS FILM OR MICROPOROUS BIAXIALLY STRETCHED FILM

摘要

PROBLEM TO BE SOLVED: To provide a method for obtaining a chemically modified cellulose nanofiber (chemically modified CeNF) reinforced microporous membrane which has a high void ratio and excellent air permeability, and has improved dynamic physical properties and heat resistance.SOLUTION: A method for producing a microporous membrane or a microporous stretched film includes: preparing a resin composition which contains polypropylene (PP) as a resin component, and contains 0.01-10 pts.wt. of chemically modified CeNF and 0.01-3 pts.wt. of a β crystal-nucleating agent, with respect to 100 pts.wt. of the resin component; melting and forming the resin composition into a film-like object where a crystal phase of a polypropylene component in the resin composition is substantially a β crystal phase, and a β-crystallization forming ability is preferably 70% or more; and then stretching the film-like object at a temperature of 90-155°C.SELECTED DRAWING: None