US4178419A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Process and product
Assignee: EIDP Inc
•
Filing: 1978-02-27
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Granted: 1979-12-11
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Expires: 1998-02-27
Abstract
Abstract Aromatic polyamide foams having a density of 0.025 to 0.7 g./cm. 3 are prepared by heating N,N'-dialkyl aromatic polyamides having at least one β hydrogen atom on the alkyl groups, a plasticizer and an aromatic sulfonic acid catalyst at 250° to 340° C. for a length of time sufficient to remove substantially all of the N-alkyl groups.
Inventors
- 👤 Wesley Memeger, Jr.
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 16:07
CPC Classifications
C; C08; C08J; C08J9/00; C08J9/02; C08G; C08G69/00; C08G69/48; C08J2377/00; C08J2377/10; Y; Y10; Y10S; Y10S264/00; Y10S264/05
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
69 words
Process for preparing an aromatic polyamide foam having a density of 0.025 to 0.7 g./cm 3 by heating a mixture of an N,N'-dialkyl aromatic polyamide having at least one β hydrogen atom on the alkyl groups and a plasticizer at a temperature of 250° to 340° C. for a time sufficient to remove substantially all of the N-alkyl groups wherein the mixture contains an aromatic sulfonic acid as catalyst.
Claim 2
Dependent Claim
69 words
Process for preparing an aromatic polyamide foam having a density of 0.025 to 0.7 g./cm 3 by heating a mixture of an N,N'-dialkyl aromatic polyamide having at least one β hydrogen atom on the alkyl groups and a plasticizer at a temperature of 250° to 340° C. for a time sufficient to remove substantially all of the N-alkyl groups wherein the mixture contains an aromatic sulfonic acid as catalyst.
Claim 3
Dependent Claim
13 words
Process of claim 1 wherein the heating is for 150 to 300 minutes.
Claim 4
Dependent Claim
19 words
Process of claim 1 wherein substantially all the N-alkyl groups are unsymmetrical and contain 4 to 8 carbon atoms.
Claim 5
Dependent Claim
9 words
Process of claim 3 wherein the plasticizer is o-dichlorobenzene.
Claim 6
Dependent Claim
10 words
Process of claim 3 wherein the catalyst is benzenesulfonic acid.
Claim 7
Dependent Claim
15 words
Process of claim 5 wherein the plasticizer is o-dichlorobenzene and the N-alkyl groups are sec-butyl.
Claim 8
Dependent Claim
12 words
Process of claim 6 wherein the N,N'-dialkyl aromatic polyamide is poly(N,N'-di-sec-butyl-p-phenylene terephthalamide).
References Cited (Backward Citations)
US3770669A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1982-12-10 | 1983-06-11 | 1983-12-11 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1986-12-10 | 1987-06-11 | 1987-12-11 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1990-12-10 | 1991-06-11 | 1991-12-11 | $7700.00 | Window Closed / Lapsed |