US3712930A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Process for polymerization of tetrahydrofuran
Assignee: Kao Corp
•
Filing: 1970-02-24
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Granted: 1973-01-23
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Expires: 1990-02-24
Abstract
Abstract TETRAHYDROFURAN IS POLYMERIZED IN THE PRESENCE OF A CATALYST OF FUMING SULFURIC ACID CONTAINING FROM 15-43 WT. PERCENT OF SO2. THE AMOUNT OF THE CATALYST IS IN THE RANGE OF 10-40 PARTS BY WEIGHT OF CATALYST PER 100 PARTS BY WEIGHT OF TETRAHYDROFURAN. THE POLYMERIZATION TEMPERATURE IS IN THE RANGE OF FROM -40*C. TO ABOUT +100*C.
Inventors
- 👤 K Matsuda
- 👤 Y Tanaka
- 👤 T Sakai
- 👤 I Iwasa
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 13:48
CPC Classifications
C; C08; C08G; C08G65/00; C08G65/02; C08G65/04; C08G65/06; C08G65/16; C08G65/20; C08G18/00; C08G18/06; C08G18/28; C08G18/40; C08G18/48; C08G18/4854
Claims Analysis
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References Cited (Backward Citations)
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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) | 1976-01-23 | 1976-07-24 | 1977-01-23 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-01-23 | 1980-07-24 | 1981-01-23 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-01-23 | 1984-07-24 | 1985-01-23 | $7700.00 | Window Closed / Lapsed |