Polyimide powder and method for producing the same

Claim 1

A polyimide powder having pleats formed on the outer circumferential surface thereof comprising spherical polyimide particles having a particle size distribution of from 0.5 to 20 μm and a mean particle diameter of from 1 to 15 μm, and comprising a repeating unit represented by the formula ##STR6## wherein Ar represent an aromatic diamine residue, which polyimide powder is formed by the process which comprises: preparing a solution of a high molecular weight polyamide acid obtained by reacting biphenyltetracarboxylic dianhydrides and an aromatic diamino compound; heating the solution to a temperature of from 140°to 250° C. to imidate the polyamide acid while simultaneously removing condensation water produced by the imidation from the solution, thereby precipitating polyimide articles to yield a slurry; separating the polyimide particles from the slurry; and drying the polyimide particles by heating at a temperature of from 100°to 400° C. to thereby obtain said polyimide powder.