Process for preparing polyimide film

Abstract

There is provided a process for preparing a polyimide film by a method of casting a film, wherein bubble inclusion and unevenness in thickness are prevented without decrease in mechanical strength at the same time. It is an object of the present invention to provided a process for preparing a polyimide film characterized by extruding, casting and forming into a film a composition of a resin solution obtained by adding, to low viscosity varnish obtained by polymerizing a tetracarboxylic dianhydride component with a diamine component in a molar ratio of 1:1.01 to 1:1.05, or 1:0.95 to 1:0.99, a dehydrating agent in a molar ratio of at least one time and a chemically-imidizing catalyst in a molar ratio of at least half time based on 1 mole of the amic acid of the poly(amic acid) varnish.

Dependencies are inferred from the claim text.