Process for producing polyimide tubes

Abstract

A process for producing a polyimide tube which comprises applying a solution of polyamide acid obtained by reacting a biphenyltetracarboxylic acid dianhydride represented by the general formula ##STR1## with an aromatic diamine in an organic polar solvent to at least one surface of a polyimide film, drying thereafter the film with heating to convert a part of the polyamide acid into the imide form while controlling the volatile material content to about 5 to 60% by weight, by which a compound film having a heat-fusible layer composed of a polyimide precursor is obtained, winding the compound film on a heat resistant core material, heating to unify the compound film by the heat-fusible layer, and removing the heat resistant core material to obtain the polyimide tube.

Dependencies are inferred from the claim text.