Process for the preparation of polyimide film

Claim 1

A process for the preparation of a polyimide film comprising the steps of: evenly coating unto the surface of a solid film, a surface treating solution which contains at least one heat-resistant surface treating agent selected from the group consisting of aminosilane type, epoxysilane type and titanate type in an amount of not less than 0.5 wt. % and has a water content of not higher than 20 wt. %; said solid film being formed of an aromatic polymer composition which contains 100 parts by weight of an aromatic polyamic acid and 5-150 parts by weight of an organic polar solvent, said aromatic polyamic acid being produced by polymerization of an aromatic tetracarboxylic acid component and an aromatic diamine component in essentially equimolar amounts wherein the tetracarboxylic acid component contains a biphenyltetracarboxylic acid or a dianhydride thereof in an amount of not less than 60 mol % and the aromatic diamine component contains a phenylene diamine in an amount of not less than 50 mol %; and heating said solid film having the coated surface treating solution thereon to a temperature of 100°-600° C. to imidize the polyamic acid constituting said solid film and simultaneously to dry said film.