Patent ID: 9656213
Date: 2017-05-23
CPC Classifications: B01D,B29C,H01M,Y02E

Claim:
1. A method of producing a microporous polymer membrane based on a dry process, comprising: providing a polymer material; melting the polymer material; extruding the molten polymer material through a T die to obtain a precursor film; cooling and crystallizing the molten polymer material using an air knife; extending the precursor film by drawing at a high temperature; annealing the extended precursor film; primary uniaxial dry stretching the annealed precursor film at a low temperature at a stretch ratio of 50% to 200%; forming a preliminary membrane by subjecting the primary stretched film to secondary stretching at a high temperature; and forming a microporous polymer membrane by heat setting the preliminary membrane, wherein the extending the precursor film is performed using a biaxial extending device, and the step of forming the preliminary membrane comprises: preparing slit-like pores by subjecting the primary stretched film to secondary biaxial dry stretching in a machine direction; and forming the preliminary membrane by subjecting the film having the slit-like pores to biaxial dry stretching in a transverse direction perpendicular to the machine direction of the uniaxial dry stretching at a stretch ratio of 10%-30%.