Polyamide acid, process for producing same and polyimide obtained therefrom

Claim 2

A polyamide acid that is the reaction product of 2,3,5-tricarboxycyclopentyl-acetic acid or its anhydride and a diamine, which has an absorption of a stretching vibration of a carbonyl group at 1,600-1,700 cm -1 due to an amide group in its infrared absorption spectrum.

Claim 3

A polyamide acid according to claim 1, wherein said diamine is a diamine represented by H 2 N--R--NH 2 , wherein R is a divalent aromatic group, a divalent aliphatic hydrocarbon group, or a divalent alicyclic hydrocarbon group.

Claim 4

A polyamide acid according to claim 2, wherein R is an aromatic group represented by: ##STR4## wherein X 1 , X 2 , X 3 and X 4 , which may be identical or different, represent H or CH 3 , Y represents >CH 2 , >C 2 H 4 , --O--, --S--, ##STR5## >SO 2 or --CONH--, and n represents 0 or 1; an aliphatic hydrocarbon group represented by --(CH 2 ) m -- in which m represents an integer of 2-9 or ##STR6## an alicyclic hydrocarbon group represented by ##STR7## or a norbornane hydrocarbon group.

Claim 5

A polyamide acid according to claim 1, wherein said diamine is p-phenylenediamine, m-phenylenediamine, 4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenylethane, 2,2-di-(p-aminophenyl)-hexafluoropropane, benzidine, 4,4'-diaminodiphenyl sulfide, 4,4'-diaminodiphenyl sulfone, 4,4'-diaminodiphenyl ether, 1,5-diaminonaphthalene, 3,3'-dimethyl-4,4'-diaminobiphenyl, 3,4'-diaminobenzanilide, 3,4'-diaminodiphenyl ether, m-xylylenediamine, p-xylylenediamine, ethylenediamine, propanediamine, tetramethylenediamine, hexamethylenediamine, heptamethylenediamine, octamethylenediamine, nonamethylenediamine, 4,4-dimethylheptamethylenediamine, 1,4-diaminocyclohexane, tetrahydrodicyclopentadienylenediamine, hexahydro-4,7-methanoindanylenedimethylenediamine or tricyclo[6,2,1,0 2 .7 ]-undecylenedimethyldiamine.

Claim 6

A polyamide acid according to claim 1, wherein the intrinsic viscosity of said polyamide acid is 0.05 dl/g or more as measured at 30° C. in N-methyl-2-pyrrolidone.

Claim 7

A polyamide acid according to claim 1, wherein the intrinsic viscosity of said polyamide acid is 0.05-5 dl/g as measured at 30° C. in N-methyl-2-pyrrolidone.

Claim 8

A process for producing a polyamide acid which comprises reacting 2,3,5-tricarboxycyclopentyl-acetic acid or its anhydride and a diamine in an organic solvent, wherein said acetic acid or its anhydride and said diamine are present in a molar ratio of 1:0.7-1.3, and said reaction is carried out at 0°-300° C.

Claim 9

A process for producing a polyamide acid which comprises reacting 2,3,5-tricarboxycyclopentyl-acetic acid or its anhydride and a diamine in an organic solvent, wherein said acetic acid or its anhydride and said diamine are present in a molar ratio of 1:0.7-1.3, and said reaction is carried out at 0°-300° C.

Claim 10

A process according to claim 7, wherein the molar ratio between 2,3,5-tricarboxycyclopentyl-acetic acid or its anhydride and a diamine is 1.

Claim 11

A process according to claim 7, wherein the amount of the solvent is 0.5-20 parts by weight per part by weight of the total amount of 2,3,5-tricarboxycyclopentyl-acetic acid or its anhydride and a diamine.

Claim 12

A process according to claim 7, wherein 2,3,5-tricarboxycyclopentyl-acetic acid and a diamine are reacted at 50°-300° C.

Claim 13

A process according to claim 7, wherein 2,3,5-tricarboxycyclopentyl-acetic acid anhydride and a diamine are reacted at 0°-100° C.

Claim 14

A process according to claim 7, wherein said diamine is a diamine represented by H 2 N--R--NH 2 , wherein R is a divalent aromatic group, a divalent aliphatic hydrocarbon group, or a divalent alicyclic hydrocarbon group.

Claim 15

A process according to claim 12, wherein R is a divalent aromatic group represented by: ##STR8## wherein X 1 , X 2 , X 3 and X 4 , which may be identical or different, represent H or CH 3 , Y represents >CH 2 , >C 2 H 4 , --O--, --S--, ##STR9## >SO 2 or --CONH--, and n represents 0 or 1; an aliphatic hydrocarbon group represented by --(CH 2 ) m -- in which m represents an integer of 2-9 or ##STR10## an alicyclic hydrocarbon group represented by ##STR11## or a norbornane hydrocarbon group.

Claim 16

A process according to claim 7, wherein said solvent is an aprotic dipole polar solvent.

Claim 17

A polyimide exhibiting absorptions of stretching vibration of carbonyl group, at two positions of 1,650-1,730 cm -1 and 1,730-1,790 cm -1 due to imide group in its infrared absorption spectrum, which is obtained by heat-treating a polyamide acid that is the reaction product of 2,3,5-tricarboxycyclopentyl-acetic acid or its anhydride and a diamine.

Claim 18

A polyimide exhibiting absorptions of stretching vibration of carbonyl group, at two positions of 1,650-1,730 cm -1 and 1,730-1,790 cm -1 due to imide group in its infrared absorption spectrum, which is obtained by heat-treating a polyamide acid that is the reaction product of 2,3,5-tricarboxycyclopentyl-acetic acid or its anhydride and a diamine.

Claim 19

A process for producing a polyimide which comprises reacting 2,3,5-tricarboxycyclopentyl-acetic acid or its anhydride and a diamine in a molar ratio of 1:0.7-1.3 in an organic solvent and directly heating the resulting polyamide acid solution at a temperature of 100°-500° C., or adding said polyamide acid solution to a non-solvent to coagulate the polyamide acid, molding the coagulated polymer and then heating it, or again dissolving the coagulated product in a solvent and heating the resulting solution.

Claim 20

A process for producing a polyimide which comprises reacting 2,3,5-tricarboxycyclopentyl-acetic acid or its anhydride and a diamine in a molar ratio of 1:0.7-1.3 in an organic solvent and directly heating the resulting polyamide acid solution at a temperature of 100°-500° C., or adding said polyamide acid solution to a non-solvent to coagulate the polyamide acid, molding the coagulated polymer and then heating it, or again dissolving the coagulated product in a solvent and heating the resulting solution.

Claim 21

A process according to claim 16, wherein said solvent is an aprotic dipole polar solvent.