POLYIMIDE PRECURSOR SOLUTION, PREPARATION THEREOF, COATING FILM PREPARED THEREFROM AND PREPARATION THEREOF

摘要

PROBLEM TO BE SOLVED: To provide a high-concentration low-viscosity polyimide precursor solution which gives a coating film having good physical properties by dissolving a salt formed of a carboxylic acid and a diamine in a solvent. SOLUTION: The salt formed of a carboxylic acid represented by formula I and the diamine represented by formula II is used. In the formulas, R is a tetravalent aromatic residue containing at least one 6-membered ring, and four carbonyl groups are directly bonded to four different carbon atoms of the residue and form two pairs of carbonyl groups, the two carbonyl groups of each pair being bonded to adjacent two carbon atoms of the 6-membered ring; R' is a divalent aromatic residue containing at least one 6-membered ring; R" is H or a 7C or lower monovalent organic group; R"' is a divalent aromatic group containing at least one 6-membered ring; and n is 1-20. Preferably, the concentration polyimide precursor in the solution is preferably 30 wt.% or higher, and the viscosity of the solution is 100 P or lower.