Abstract: A polyimide powder for an antistatic polyimide molded product is disclosed. The polyimide powder comprises a polyimide-powder prepared from an aromatic tetracarboxylic acid component and a diamine component, and a conductive carbon black having a DBP oil absorption of 300 ml/100 g or more; wherein the amount of the conductive carbon black is within a range of 0.75 wt % to 5 wt % relative to the polyimide-powder. A polyimide molded product with sufficient antistatic property can be formed by molding the above polyimide powder.

Abstract: A flexible circuit printable board can be favorably produced by a process composed of steps of forming in a polyimide film having a metal coat on each surface side a via hole penetrating at least one metal coat and the polyimide film; and applying a mixture of liquid and abrasive grains under pressure onto the via hole, whereby smoothing an edge of the via hole and cleaning the via hole.

Abstract: Continuous inorganic fibers consisting substantially of Si, Zr and C and optionally of O, said fibers being composed of (1) an amorphous material consisting substantially of Si, Zr and C and optionally of O, or (2) an aggregate consisting substantially of ultrafine crystalline particles of .beta.-SiC, ZrC, a solid solution of .beta.-SiC and ZrC and ZrC.sub.1-x wherein 0<x<1 and having a particle diameter of not more than 500.ANG., in which amorphous SiO.sub.2 and ZrO.sub.2 sometimes exist in the neighborhood of these ultrafine crystalline particles, or (3) a mixture of said amorphous material (1) and said aggregate (2) of ultrafine crystalline particles. The aforesaid continuous inorganic fibers can be produced by the following steps: a first step of preparing a semi-inorganic block copolymer comprising polycarbosilane blocks having a main chain skeleton composed mainly of carbosilane units of the formula --Si--CH.sub.