US4263410A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Ambient cure polyimide foam
Assignee: Boeing North American Inc
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Filing: 1980-02-19
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Granted: 1981-04-21
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Expires: 2000-02-19
Abstract
Abstract A polyimide foam is provided which has improved resistance to crumbling and to high temperatures. The foam is produced by reacting polymethylene polyphenylisocyanate (PAPI) with benzophenone-3,3',4,4'-tetracarboxylic acid dianhydride (BTDA) in the presence of furfuryl alcohol and concentrated phosphoric acid (PA). The ratio of PA to PAPI, (PA/PAPI), must be approximately 20 to 26% by weight.
Inventors
- 👤 Chiang-Ying M. Tung
- 👤 Charles L. Hamermesh
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 22:51
CPC Classifications
C; C08; C08J; C08J9/00; C08J9/02; C08G; C08G18/00; C08G18/06; C08G18/28; C08G18/30; C08G18/34; C08G18/343; C08G18/346; C08G18/67; C08G18/671; C08G18/674; C08G73/00; C08G73/06; C08G73/10; C08G73/1003; C08G73/1035; C08J2379/00; C08J2379/04; C08J2379/08
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
87 words
An improvement in a process for preparing a fire-resistant foam by the reaction of an aromatic polyisocyanate and an aromatic polycarboxylic compound in the presence of furfuryl alcohol and a strong inorganic acid, said improvement comprising: selecting polymethylene polyphenylisocyanate (PAPI) from said aromatic polyisocyanates; selecting benzophenone-3,3',4,4'-tetracarboxylic acid dianhydride (BTDA) from said aromatic polycarboxylic compounds; selecting phosphoric acid (PA) from said strong inorganic acids; and carrying out said reaction using a ratio of said phosphoric acid to said polymethylene polyphenylisocyanate (PA/PAPI) of approximately 20 to 26% by weight.
Claim 2
Dependent Claim
87 words
An improvement in a process for preparing a fire-resistant foam by the reaction of an aromatic polyisocyanate and an aromatic polycarboxylic compound in the presence of furfuryl alcohol and a strong inorganic acid, said improvement comprising: selecting polymethylene polyphenylisocyanate (PAPI) from said aromatic polyisocyanates; selecting benzophenone-3,3',4,4'-tetracarboxylic acid dianhydride (BTDA) from said aromatic polycarboxylic compounds; selecting phosphoric acid (PA) from said strong inorganic acids; and carrying out said reaction using a ratio of said phosphoric acid to said polymethylene polyphenylisocyanate (PA/PAPI) of approximately 20 to 26% by weight.
Claim 3
Dependent Claim
44 words
The improvement as claimed in claim 1, wherein said step of carrying out said reaction is accomplished using the following percent by weight of ingredients: PAPI 37 to 42%; BTDA 18 to 21%, furfuryl alcohol 28 to 32%; and phosphoric acid 8 to 10%.
Claim 4
Dependent Claim
44 words
A temperature resistant foam produced by: reacting polymethylene polyphenylisocyanate (PAPI) with benzophenone-3,3',4,4'-tetracarboxylic acid dianhydride (BTDA) in the presence of furfuryl alcohol and phosphoric acid (PA), wherein the ratio of said phosphric acid to said polymethylene polyphenylisocyanate, (PA/PAPI), is approximately 20 to 26% by weight.
Claim 5
Dependent Claim
44 words
A temperature resistant foam produced by: reacting polymethylene polyphenylisocyanate (PAPI) with benzophenone-3,3',4,4'-tetracarboxylic acid dianhydride (BTDA) in the presence of furfuryl alcohol and phosphoric acid (PA), wherein the ratio of said phosphric acid to said polymethylene polyphenylisocyanate, (PA/PAPI), is approximately 20 to 26% by weight.
Claim 6
Dependent Claim
37 words
The temperature resistance foam as claimed in claim 3, wherein the percent by weight of the reactants is: PAPI 37 to 42%; BTDA 18 to 21%; furfuryl alcohol 28 to 32%; and phosphoric acid 8 to 10%.
References Cited (Backward Citations)
US3772216A
Cited
US4184021A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1984-04-20 | 1984-10-20 | 1985-04-21 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1988-04-20 | 1988-10-20 | 1989-04-21 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1992-04-20 | 1992-10-20 | 1993-04-21 | $7700.00 | Window Closed / Lapsed |