To obtain a lubricant paste which has a low viscosity and is easily applicable even when its solid content is high by mixing a lubricant powder into a varnish prepd. by dissolving, in an org. solvent, a polyimide precursor formed from a diamine and a tetracarboxylic acid and/or its ester.
A lubricant powder is mixed into a varnish which is prepd. by dissolving a polyimide precursor formed from (A) a diamine of formula I and (B) a tetracarboxylic acid and/or its ester of formula II in an org. solvent in a concn. of the precursor of 5-80 wt.%. In the formulas, R1 and R2 are selected from the groups represented by formula III, etc., and from the groups represented by formula IV, etc., respectively; R3 to R8 are each H or 1-5C alkyl; and m is an integer of 0-10. Pref., the wt. ratio of A/B is (20/80)-(99/1), and 0.5-200 pts.wt. lubricant powder is mixed into 100 pts.wt. polyimide precursor varnish.
SHIGETA AKIRA
ECHIGO YOSHIAKI
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