Patent ID: 10189968

Abstract:
Provided are a varnish for porous polyimide film production, providing an unburned composite film that is less likely to have a sea-island structure, and a method for producing a porous polyimide film using the same. The varnish according to the present invention comprises a resin including polyamide acid and/or polyimide, fine particles, and a solvent, and has a fine particle content of not less than 65% by volume relative to the total of the resin and the fine particles and a viscosity at 25° C. of not less than 550 mPa·s. Preferably, the varnish further comprises a dispersant. The method for producing a porous polyimide film according to the present invention comprises: forming an unburned composite film using the varnish; burning the unburned composite film to obtain a polyimide-fine particle composite film; and removing the fine particles from the polyimide-fine particle composite film.