POLYIMIDE PRECURSOR SOLUTION, ITS PRODUCTION, COATING FROM MADE FROM IT, AND ITS PRODUCTION

摘要

PROBLEM TO BE SOLVED: To obtain a polyimide precursor solution which is lowly viscous in spite of having a high concentration and gives a coating film having good properties by including a solute comprising a diamine having a specified structure and a tetracarboxylic acid or its ester. SOLUTION: This solution is prepared by adding a solute comprising a diamine (A) represented by formula I and (B) a tetracarboxylic acid represented by formula II or its ester in a ratio component A/component B of 1 mol/0.95-1.05 mol to an aprotic polar solvent (e.g. N-methylpyrrolidone) and having a concentration of at least 5 wt.% and a viscosity of at most 80 P. Component A is obtained by reacting 1 mol of a diamine represented by the formula: H2N-R2- NH2 with 0.4-0.9 mol of an aromatic tetracarboxylic dianhydride in an aprotic polar solvent. In the formula, R1 and R3 are each a tetravalent aromatic residue containing at least one six-membered carbocyclic ring; R2 is a divalent aromatic residue having at least one six-membered carbocyclic ring; m is 1-20; and R4 to R7 are each hydrogen or a 1-5C alkyl.