Patent ID: 10968328

Abstract:
The present invention pertains to a porous polyimide film production method and a porous polyimide film produced using said method, said method including: a step (1) in which a poly(amic acid) solution comprising 40%-97% by mass organic polar solvent and 3%-60% by mass poly(amic acid) having an intrinsic viscosity, comprising tetracarboxylic acid units and diamine units, of 1.0-3.0 is cast in film form and immersed in or caused to come in contact with a coagulating solvent having water as an essential component thereof, and a porous film of poly(amic acid) is produced; and a step (2) in which the porous film of poly(amic acid) obtained in said step is heat treated and imidized. Shrinkage in the film longitudinal direction and transverse direction after heat treatment is suppressed to no more than 8% for each direction and the speed of temperature increase in a temperature range of at least 200° C. during the heat treatment is at least 25° C./min.