US5243093A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Process and composition
Assignee: Sulzer Canada Inc
•
Filing: 1991-04-08
•
Granted: 1993-09-07
•
Expires: 2011-04-08
Abstract
Abstract A method comprising purifying impure bisphenol-A by fractional melt crystallization in a falling film dynamic crystallizer.
Inventors
- 👤 Gaylord M. Kissinger
- 👤 Nicholas P. Wynn
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 04:03
CPC Classifications
C; C07; C07C; C07C39/00; C07C39/12; C07C37/00; C07C37/68; C07C37/70; C07C37/84
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
16 words
A method comprising purifying impure bisphenol-A by fractional melt crystallization in a falling film dynamic crystallizer.
Claim 2
Independent Claim
16 words
A method comprising purifying impure bisphenol-A by fractional melt crystallization in a falling film dynamic crystallizer.
Claim 3
Dependent Claim
19 words
A method in accordance with claim 1 wherein the purity of the purified bisphenol-A is better than about 99.80%.
Claim 4
Dependent Claim
16 words
A method in accordance with claim 1 wherein the purification is carried out in multiple stages.
Claim 5
Dependent Claim
13 words
A method in accordance with claim 2 wherein orthorhombic crystalline bisphenol-A is prepared.
Claim 6
Dependent Claim
19 words
The process in accordance with claim 1 wherein the per pass yield of bisphenol-A is at least about 75%.
References Cited (Backward Citations)
US3621664A
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USRE32241E
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GB1198160A
Cited
US4113974A
Cited
WO1980000150A1
Cited
US4354046A
Cited
EP0146170A1
Cited
US4927973A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1996-09-06 | 1997-03-08 | 1997-09-07 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2000-09-06 | 2001-03-08 | 2001-09-07 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2004-09-06 | 2005-03-08 | 2005-09-07 | $7700.00 | Window Closed / Lapsed |