| abstract |
(57) Abstract: In a method for producing a microporous film, at least two layers of the same or different thermoplastic resins (A) 15 to 90 parts by volume, a microporous material which can be extracted, has a viscosity at 200 ° C. of 1000 cps or less, and contains 85 to 10 parts by volume of an inert organic liquid substance (B) as a main component The formed precursor layer was extruded with an annular die, the precursor layer was quenched and solidified with a heat transfer medium, and then 15 ° C. or more and 50 ° C. were added to the Vicat softening point of the thermoplastic resin (A) constituting the precursor layer. A method for producing a microporous film in which a microporous film is obtained by stretching in at least one direction at an area magnification of 2 times or more and 70 times or less under a temperature condition of not more than a temperature and then extracting the substance (B). |