US2939178A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Process for molding sintered polytetrafluoroethylene articles
Assignee: Continental-Diamond Fibre Corp
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Filing: 1958-04-30
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Granted: 1960-06-07
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Expires: 1978-04-30
Abstract
No abstract record available.
Inventors
- 👤 Arthur H Haroldson
- 👤 George H Watrous
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 15:08
CPC Classifications
B; B29; B29C; B29C43/00; B29C43/006; B29K; B29K2105/00; B29K2105/25; B29K2105/251
Claims Analysis
Total Claims: 1
Claim 1
Independent Claim
139 words
THE METHOD OF MOLDING POLYTETRAFLUOROETHYLENE TO PRODUCE SOUND ARTICLES FREE FROM POROSITY AND CRACKS AND FREE FROM HARD LEATHERY TEXTURE EVEN WHEN RECLAIMED MATERIAL IS USED, WHICH COMPRISES, COLD-PRESSING POWDERED RECLAIMED POLYTETRAFLUOROETHYLENE MATERIAL UNDER PRESSURE OF 500 TO 3000 P.S.I. TO MAKE A DENSE COHERENT PREFORM, CLOSED MOLD OF A SIZE TO ALLOW LIMITED EXPANSION OF 15% TO 35% AND THEREAFTER TO CREATE HIGH PRESSURE OF 400 TO 1800 P.S.I. IN THE MATERIAL UNDER COMPLETE CONFINEMENT WITHOUT ESCAPE OF MATERIAL, SINTERING THE PREFORM IN THE MOLD WITH CONCURRENT EXPANSION OF THE MATERIAL BUT WITHOUT ESCAPE OF MATERIAL UNTIL THE DESIRED PRESSURE IS CREATED, AND SUBSEQUENTLY COOLING THE SINTERED PREFORM IN A MOLD WITH A CONTINUOUSLY APPLIED FOLLOW-UP PRESSURE SUFFICIENT TO MATERIALLY REDUCE THE SIZE OF THE BODY OF MATERIAL IN THE MOLD UNTIL THE MATERIAL IS COOL AND DENSE.
References Cited (Backward Citations)
US2400094A
Cited
US2456262A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1963-06-07 | 1963-12-07 | 1964-06-07 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1967-06-07 | 1967-12-07 | 1968-06-07 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1971-06-07 | 1971-12-07 | 1972-06-07 | $7700.00 | Window Closed / Lapsed |