Patent US4861537A successfully refreshed from Google Patents.
US4861537A
Expired / Lapsed
US
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Process of making a sintered polybenzimidazole article
Assignee: CNA Holdings LLC
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Filing: 1988-07-25
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Granted: 1989-08-29
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Expires: 2008-07-25
Abstract
Abstract Sintered polybenzimidazole articles are obtained by compacting a particulate, dried polybenzimidazole resin under a pressure of 2,000 to 10,000 psi in a mold, heating the formed article to a temperature in the range of 825° to 950° F. for at least four hours, cooling the polybenzimidazole article to below 800° F. while maintaining the article under a pressure of 2,000 to 10,000 psi, and thereafter heating the constrained formed polybenzimidazole article to a temperature in the range of 825° to 950° F. for at least one hour.
Inventors
- 👤 Bennett C. Ward
- 👤 Edwardo Alvarez
- 👤 Ralph S. Blake
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 16:05
CPC Classifications
C; C08; C08G; C08G73/00; C08G73/06; C08G73/18
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
178 words
A process which comprises compacting a particulate polybenzimidazole resin having a particle size such that the particles pass through a 100 mesh screen in a mold to a pressure in the range of 2,000 to 20,000 psi at ambient temperature for a period of at least one minute, said resin having a water and volatiles concentration below 0.1 weight percent and an IV of at least 0.4, heating the compacted polybenzimidazole resin in a first heating step to a temperature in the range of 825° to 950° F. and maintaining said compacted polybenzimidazole resin in said temperature range for a period of at least four hours so as to form a molded article, cooling said polybenzimidazole molded article to a temperature below 800° F. while maintaining said article under a pressure in the range of 2,000 to 20,000 psi, and thereafter heating the formed polybenzimidazole article to a temperature in the range of 825° to 950° F. in a second heating step under constraint, maintaining the article at this temperature for a period of at least one hour.
Claim 2
Dependent Claim
178 words
A process which comprises compacting a particulate polybenzimidazole resin having a particle size such that the particles pass through a 100 mesh screen in a mold to a pressure in the range of 2,000 to 20,000 psi at ambient temperature for a period of at least one minute, said resin having a water and volatiles concentration below 0.1 weight percent and an IV of at least 0.4, heating the compacted polybenzimidazole resin in a first heating step to a temperature in the range of 825° to 950° F. and maintaining said compacted polybenzimidazole resin in said temperature range for a period of at least four hours so as to form a molded article, cooling said polybenzimidazole molded article to a temperature below 800° F. while maintaining said article under a pressure in the range of 2,000 to 20,000 psi, and thereafter heating the formed polybenzimidazole article to a temperature in the range of 825° to 950° F. in a second heating step under constraint, maintaining the article at this temperature for a period of at least one hour.
Claim 3
Dependent Claim
21 words
The process of claim 1 wherein the pressure maintained in the compaction and cooling process steps is at least 5,000 psi.
Claim 4
Dependent Claim
20 words
The process of claim 2 wherein the temperature maintained in the first heating process step is at least 875° F.
Claim 5
Dependent Claim
40 words
The process of claim 1 wherein said polybenzimidazole resin is dried prior to the compaction step by heating said resin to a temperature of at least 350° F. and maintaining said resin at this temperature for at least 4 hours.
Claim 6
Dependent Claim
15 words
The process of claim 1 wherein the first heating step is conducted at ambient pressure.
Claim 7
Dependent Claim
17 words
The process of claim 1 wherein the addition of a filler is included in the compacting step.
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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) | 1992-08-28 | 1993-02-27 | 1993-08-29 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1996-08-28 | 1997-02-27 | 1997-08-29 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2000-08-28 | 2001-02-27 | 2001-08-29 | $7700.00 | Window Closed / Lapsed |