Patent US2438936A successfully refreshed from Google Patents.
US3407249A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Porous, extensively fibrillated polytetrafluoroethylene and method of preparing same
Assignee: Wyeth Holdings LLC
•
Filing: 1966-02-28
•
Granted: 1968-10-22
•
Expires: 1986-02-28
Abstract
No abstract record available.
Inventors
- 👤 Landi Henry Patrick
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-22 19:02
CPC Classifications
H; H01; H01M; H01M4/00; H01M4/86; B; B01; B01D; B01D67/00; B01D67/0002; B01D67/0023; B01D67/003; B01D71/00; B01D71/06; B01D71/30; B01D71/32; B01D71/36; C; C08; C08J; C08J9/00; C08J9/26; C08K; C08K3/00; C08K3/01; C08K3/013; C08K3/18; C08K3/20; C08K3/22; C08K3/30; H01M50/00; H01M50/40; H01M50/409; H01M50/44; C08J2327/00; C08J2327/02; C08J2327/12; C08J2327/18; H01M50/446; Y; Y02; Y02E; Y02E60/00; Y02E60/10; Y02E60/30; Y02E60/50; Y10; Y10S; Y10S264/00; Y10S264/08; Y10T; Y10T428/00; Y10T428/31504; Y10T428/3154
Claims Analysis
Total Claims: 2
Claim 1
Independent Claim
111 words
A METHOD FOR PREPARING A POROUS, UNSINTERED, COMPLETELY FIBRILLATED POLYTETRAFLUOROETHYLENE SHEET WHICH COMPRISES: INTIMATELY BLENDING FROM ABOUT 1% TO ABOUT 40%, BY WEIGHT, OF POLYTETRAFLUOROETHYLENE IN THE FORM OF AN AQUEOUS DISPERSION AND FROM ABOUT 98% TO 40%, BY WEIGHT, OF AN ORGANIC-SOLVENT EXTRACTABLE VISCOUS POLYMER, BASED ON THE WEIGHT OF THE OVERALL MIXTURE; MILLING THE LATTER MIXTURE AT TEMPERATURES RANGING FROM ABOUT 170*C. TO ABOUT 200*C.; EXTRUDING THE MILLED PRODUCT TO FROM A SHEET; IMMERSING SAID FORMED SHEET IN AN ORGANIC SOLVENT SELECTIVE FOR THE SOLVENT EXTRACTABLE VISCOUS POLYMER THEREBY DISSOLVING THE LATTER POLYMER FROM SAID FORMED SHEET; AND RECOVERING THE LATTER AS A POROUS, UNSINTERED, COMPLETELY FIBRILLATED POLYTETRAFLUOROETHYLENE SHEET.
Claim 2
Independent Claim
111 words
A METHOD FOR PREPARING A POROUS, UNSINTERED, COMPLETELY FIBRILLATED POLYTETRAFLUOROETHYLENE SHEET WHICH COMPRISES: INTIMATELY BLENDING FROM ABOUT 1% TO ABOUT 40%, BY WEIGHT, OF POLYTETRAFLUOROETHYLENE IN THE FORM OF AN AQUEOUS DISPERSION AND FROM ABOUT 98% TO 40%, BY WEIGHT, OF AN ORGANIC-SOLVENT EXTRACTABLE VISCOUS POLYMER, BASED ON THE WEIGHT OF THE OVERALL MIXTURE; MILLING THE LATTER MIXTURE AT TEMPERATURES RANGING FROM ABOUT 170*C. TO ABOUT 200*C.; EXTRUDING THE MILLED PRODUCT TO FROM A SHEET; IMMERSING SAID FORMED SHEET IN AN ORGANIC SOLVENT SELECTIVE FOR THE SOLVENT EXTRACTABLE VISCOUS POLYMER THEREBY DISSOLVING THE LATTER POLYMER FROM SAID FORMED SHEET; AND RECOVERING THE LATTER AS A POROUS, UNSINTERED, COMPLETELY FIBRILLATED POLYTETRAFLUOROETHYLENE SHEET.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1971-10-22 | 1972-04-22 | 1972-10-22 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1975-10-22 | 1976-04-22 | 1976-10-22 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1979-10-22 | 1980-04-22 | 1980-10-22 | $7700.00 | Window Closed / Lapsed |