Patent US4954144A successfully refreshed from Google Patents.
US4954144A
Expired / Lapsed
US
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Polyimide membranes and their use for gas separation
Assignee: Air Products and Chemicals Inc
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Filing: 1989-09-12
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Granted: 1990-09-04
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Expires: 2009-09-12
Abstract
Abstract The present invention is a class of polyimide membranes wherein the diamine portion of the polymer structure is formed from 2,5-di-t-butyl-1,4-phenylenediamine. Membranes formed from polyimides containing this diamine structure exhibit unexpectedly high gas permeability properties and are especially useful for separating oxygen from nitrogen or air.
Inventors
- 👤 William F. Burgoyne, Jr.
- 👤 Michael Langsam
- 👤 Robert L. Fowlkes
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 14:15
CPC Classifications
C; C08; C08G; C08G73/00; C08G73/06; C08G73/10; C08G73/1067; B; B01; B01D; B01D71/00; B01D71/06; B01D71/58; B01D71/62; B01D71/64; C08G73/1039; C08G73/1057; C08G73/1064; C08G73/1075; C08G73/1078
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
54 words
A process for separating a component of a gas mixture containing at least one other component, said process comprising bringing said gas mixture into contact with a membrane formed of a polyimide having repeating units formed from a dianhydride and 2,5-di-t-butyl-1,4-phenylene diamine, such that one component of said gas mixture selectively permeates said membrane.
Claim 2
Dependent Claim
54 words
A process for separating a component of a gas mixture containing at least one other component, said process comprising bringing said gas mixture into contact with a membrane formed of a polyimide having repeating units formed from a dianhydride and 2,5-di-t-butyl-1,4-phenylene diamine, such that one component of said gas mixture selectively permeates said membrane.
Claim 3
Dependent Claim
55 words
A process in accordance with claim 1 wherein said membrane is formed of a polyimide comprising repeating units of the general structural formula: ##STR10## wherein R 1 and R 2 are both t-butyl groups and Z is ##STR11## wherein A is C(CH 3 ) 2 , C(CF3) 2 , O, S or SO 2 .
Claim 4
Dependent Claim
19 words
A process in accordance with claim 1 wherein said gas mixture is air and oxygen selectively permeates the membrane.
Claim 5
Dependent Claim
19 words
A semi-permeable membrane formed of a polyimide wherein said polyimide comprises repeating units formed from a dianhydride and 2,5-di-t-butyl-1,4-phenylenediamine.
Claim 6
Dependent Claim
19 words
A semi-permeable membrane formed of a polyimide wherein said polyimide comprises repeating units formed from a dianhydride and 2,5-di-t-butyl-1,4-phenylenediamine.
Claim 7
Dependent Claim
53 words
A semi-permeable membrane in accordance with claim 4 wherein said polyimide comprises repeating units of the general structural formula: ##STR12## wherein R 1 and R 2 are both t-butyl groups and Z is ##STR13## wherein A is C(CH 3 ) 2 , C(CF 3 ) 2 , O, S or SO 2 .
Claim 8
Dependent Claim
18 words
A semi-permeable membrane in accordance with claim 4 wherein said polyimide comprises repeating units of the formula: ##STR14##
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1993-09-03 | 1994-03-05 | 1994-09-04 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1997-09-03 | 1998-03-05 | 1998-09-04 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2001-09-03 | 2002-03-05 | 2002-09-04 | $7700.00 | Window Closed / Lapsed |