| abstract |
(57) [PROBLEMS] To provide a method for producing a microporous membrane that uses a polyvinylidene fluoride resin having high chemical resistance, has high strength, high water permeability, and exhibits excellent separation performance. To do. A method for producing a microporous film, in which a polymer solution containing a polyvinylidene fluoride resin and a solvent is discharged from a discharge port at a temperature Ts and cooled to obtain a microporous film, the crystal of the polymer solution Temperature Tc is 40 ° C or higher 1 20 ° C. or lower, and the average temperature drop rate when the polymer solution passes through Tc during cooling is 2 × 10 3 ° C./min to 10 6 ° C. / Min or less and Ts is Tc ≦ Ts ≦ Tc + 9 A method for producing a microporous membrane that satisfies the relationship of 0. |