US4499042A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Production of heat-shrinkable polyimide films
Assignee: Nitto Denko Corp
•
Filing: 1983-04-04
•
Granted: 1985-02-12
•
Expires: 2003-04-04
Abstract
Abstract A heat-shrinkable polyimide film which comprises a polyimide film prepared by converting at least about 50% by weight of polyamide acid obtained by reacting a biphenyltetracarboxylic acid dianhydride represented by the general formula ##STR1## with an aromatic diamine into polyimide, and stretched in at least one direction to provide heat-shrinkability, and a process for producing the film.
Inventors
- 👤 Takashi Ishizuka
- 👤 Yasuhiro Moriyama
- 👤 Masao Nakamura
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 03:34
CPC Classifications
C; C08; C08G; C08G73/00; C08G73/06; C08G73/10; C08G73/1067; C08G73/1071; B; B29; B29C; B29C61/00; B29C61/003; C08G73/1057; C08G73/1064; C08G73/1075; C08G73/1078; B29K; B29K2079/00
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
117 words
A process for producing a heat-shrinkable polyimide film which comprises forming a film by flow molding a solution of organic solvent-soluble polyamide acid having an inherent viscosity of about 0.5 or more obtained by reacting a biphenyltetracarboxylic acid dianhydride represented by the general formula ##STR4## with an aromatic diamine other than aromatic azo diamines in an organic polar solvent, drying said film until the volatile material content becomes about 10% by weight or less to produce a polyimide film wherein at least about 50% by weight of polyamide acid is converted into polyimide, and stretching thereafter said polyimide film in at least one direction to a stretching ratio of about 1.05 to about 5 to provide heat-shrinkability.
Claim 2
Dependent Claim
117 words
A process for producing a heat-shrinkable polyimide film which comprises forming a film by flow molding a solution of organic solvent-soluble polyamide acid having an inherent viscosity of about 0.5 or more obtained by reacting a biphenyltetracarboxylic acid dianhydride represented by the general formula ##STR4## with an aromatic diamine other than aromatic azo diamines in an organic polar solvent, drying said film until the volatile material content becomes about 10% by weight or less to produce a polyimide film wherein at least about 50% by weight of polyamide acid is converted into polyimide, and stretching thereafter said polyimide film in at least one direction to a stretching ratio of about 1.05 to about 5 to provide heat-shrinkability.
Claim 3
Dependent Claim
49 words
The process for producing a heat-shrinkable polyimide film according to claim 1, wherein said biphenyltetracarboxylic acid dianhydride is 3,4,3',4'-biphenyltetracarboxylic acid dianhydride, 2,3,3',4'-biphenyltetracarboxylic acid dianhydride, or 2,3,2',3'-biphenyltetracarboxylic acid dianhydride and said aromatic amine is m-phenylenediamine, p-phenylenediamine, 4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenyl ether, 4,4'-diaminodiphenylpropane, 4,4'-diaminodiphenyl sulfide, 4,4'-diaminodiphenyl sulfone, 3,3'-diaminodiphenyl sulfone, 1,5-diaminonaphthalene, 2,6-diaminonaphthalene or 3,4'-diaminobenzanilide.
Claim 4
Dependent Claim
28 words
The process for producing a heat-shrinkable polyimide film according to claim 2, wherein said biphenyltetracarboxylic acid dianhydride is 3,4,3',4'-biphenyltetracarboxylic acid dianhydride and said aromatic amine is 4,4'-diaminodiphenyl ether.
Claim 5
Dependent Claim
31 words
The process for producing a heat-shrinkable polyimide film according to claim 1, wherein said film is stretched biaxially with a stretching ratio in each direction of about 1.05 to about 5.
Claim 6
Dependent Claim
28 words
The process for producing a heat-shrinkable polyimide film according to claim 1, wherein a solution of said polyamide acid has an inherent viscosity of about 0.5 or more.
Claim 7
Dependent Claim
28 words
The process for producing a heat-shrinkable polyimide film according to claim 1, wherein said polyimide film has a volatile material content of about 10% by weight or less.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1988-02-12 | 1988-08-13 | 1989-02-12 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1992-02-12 | 1992-08-13 | 1993-02-12 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1996-02-12 | 1996-08-13 | 1997-02-12 | $7700.00 | Window Closed / Lapsed |