Polyimides, process for the preparation thereof and polyimide resin compositions

A polyimide having a melt viscosity of not more than 40,000 poise at 380.degree. C. and having two or more of recurring structural units represented by the formula (V):

• ##STR55## wherein Q.sub.1 and Q.sub.2 are each groups selected from the group consisting of an aliphatic group, a alicyclic group, a monocyclic aromatic group, a fused polycyclic aromatic group and a polycyclic aromatic group combined with a member selected from the group consisting of a direct bond and a bridge member, Q.sub.1 is a divalent group and Q.sub.2 is a tetravalent group;
• said recurring structural units of the formula (V) comprising about 50% by mole or more of recurring structural units having the formula (VI):
• ##STR56## and from about 0.5 to about 50% by mole of at least one recurring structural unit of the formula:
• ##STR57## wherein Q.sub.2 is a defined above and R.sub.1 is derived from at least one diamine compound selected from (a) aminobenzylamine, phenylenediamine, diaminocyclohexane and ethylene diamine;
• (b) 4,4'-diaminobiphenyl, 3,4'-diaminobiphenyl, 3,3'-diaminobiphenyl, 4,4'-diaminobenzophenone, 3,3'-diaminobenzophenone, 3,4'-diaminobenzophenone, bis(3-aminophenyl)ether, (3-aminophenyl)(4-aminophenyl)ether, bis(3-aminophenyl)sulfide, (3-aminophenyl)(4-aminophenyl)sulfide, bis(4-aminophenyl)sulfide, bis(3-aminophenyl)sulfoxide, (3-aminophenyl)(4-aminophenyl)sulfoxide, bis(4-aminophenyl)sulfoxide, bis(3-aminophenyl)sulfone, (3-aminophenyl)(4-aminophenyl)sulfone, bis(4-aminophenyl)sulfone, 3,3'-diaminodiphenylmethane, 3,4'-diaminodiphenylmethane, 4,4'-diaminodiphenylmethane and diaminonaphthalene;
• (c) 1,3-bis(3-aminophenoxy)benzene, 1,3-bis(4-aminophenoxy)benzene, 1,4-bis(3-aminophenoxy)benzene, and 1,3-bis(4-aminophenoxy)benzene;
• (d) bis-[4-(4-aminophenoxy)phenyl]methane, 1,1-bis[4-(4-aminophenoxy)phenyl]ethane, 1,2-bis[4-(4-aminophenoxy)phenyl]ethane, 2,2-bis[4-(4-aminophenoxy)phenyl]propane, 2,2-bis[4-(4-aminophenoxy)phenyl]butane, 2,2-bis[4-(4-aminophenoxy)phenyl]-1,1,1,3,3,3-hexafluoropropane, bis[4-(4-aminophenoxy)phenyl]ketone, bis[4-(4-aminophenoxy)phenyl]sulfide, bis[4-(4-aminophenoxy)phenyl]sulfoxide, bis[4-(4-aminophenoxy)phenyl]sulfone and bis[4-(4-aminophenoxy)phenyl ether;
• (e) 1,4-bis[4-(3-aminophenoxy)benzoyl]benzene, 1,3-bis[4-(3-aminophenoxy)benzoyl]benzene, 4,4'-bis[3-(4-aminophenoxy)benzoyl]diphenyl ether, 4,4'bis[3-(3-aminophenoxy)benzoyl]diphenyl ether, 4,4'-bis[4-(4-amino-.alpha.,.alpha.-dimethylbenzyl)phenoxy]benzophenone, 4,4'-bis[4-(4-amino-.alpha.,.alpha.-dimethylbenzyl)phenoxy]diphenyl sulfone and bis[4-{4-(4-aminophenoxy)phenoxy}phenyl]sulfone.