Polyamic acid, polyimide, process for producing these, and film of the polyimide

摘要: Disclosed are a polyamic acid having repeating units represented by the formula (1): wherein norbornane skeleton of comprises four components and their contents satisfy following: 1 % ≤ 2,5-[diexo] 90 %, 2,5-[exo,endo] 2,6-[diexo] 2,6-[exo,endo] provided that (2,5-[diexo]) + (2,5-[exo,endo]) (2,6-[diexo]) (2,6-[exo,endo]) = 100 R represents from 4 to 27 carbon atoms, tetravalent group selected consisting an aliphatic group, monocyclic condensed polycyclic aromatic non-condensed or which is composed cycloaliphatic groups mutually bonded each other either directly via crosslinking member; polyimide obtained imidizing has good properties intrinsic polyimides, is, thermal resistance, mechanical properties, slidability, low water absorption, electric radiation resistance thereto. By varying composition ratio starting diamine isomers, various polyimides controlled melt flowability, optical chemical capable forming films forms can be obtained.