Polyamic acids, polyimides, and processes for the production thereof

Abstract

To provide polyamic acids and polyimides, which have high light transmittance and heat resistance such that their thermal decomposition temperatures are at least 300° C. and which are excellent in their solubility in solvents and have their processability improved. A polyamic acid comprising repeating units represented by the following formula (1), characterized in that at least 10 mol % of A has a structure represented by the formula (2), or a polyimide obtainable by cyclodehydration of such a polyamic acid. wherein A is a tetravalent organic group, B is a bivalent organic group, and n is a positive integer; and wherein each of R1 and R2 which are independent of each other, is a hydrogen atom, a halogen atom, a C1-10 alkyl group, a C1-10 halogenated alkyl group, a C3-8 cycloalkyl group, a phenyl group or a cyano group, and a1 to a4 represent binding sites in the formula (1), provided that a1 and a3 are not simultaneously bonded to the carboxyl groups, and a2 and a4 are not simultaneously bonded to the carboxyl groups.

Dependencies are inferred from the claim text.