US3668181A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Purification of polycarbonate resins
Assignee: Honeywell International Inc
•
Filing: 1970-03-06
•
Granted: 1972-06-06
•
Expires: 1990-03-06
Abstract
Abstract Crude precipitated polycarbonate resin obtained by the reaction of bisphenol A and phosgene, preferably in an aqueous alkaline emulsion containing a water-insoluble partial solvent for the resin, is purified by extraction with aqueous methanol or dimethoxy ethane or a mixture thereof.
Inventors
- 👤 Bryce C Oxenrider
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 22:26
CPC Classifications
C; C08; C08G; C08G64/00; C08G64/40; C08G64/406
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
35 words
A process in accordance with claim 1 wherein said partial solvent comprises a mixture of a halogenated C1 to C4 aliphatic hydrocarbon, a C2 to C8 aliphatic ether and a C6 to C10 aliphatic hydrocarbon.
Claim 2
Dependent Claim
29 words
A process in accordance with claim 1 wherein said precipitated polycarbonate is washed with fresh partial solvent and with water prior to said contacting with acid and extracting solvent.
Claim 3
Dependent Claim
21 words
A process in accordance with claim 1 wherein said acid is selected from the group consisting of hydrochloric, carbonic and formic.
Claim 4
Dependent Claim
12 words
A process in accordance with claim 4 wherein said acid is carbonic.
Claim 5
Dependent Claim
24 words
A process in accordance with claim 1 wherein said neutralized polycarbonate is extracted with acid-free methanol containing not more than 30 volume percent water.
Claim 6
Dependent Claim
23 words
A process in accordance with claim 1 wherein the weight ratio of extracting solvent to polycarbonate ranges from about 5:1 to about 100:1.
Claim 7
Dependent Claim
17 words
A process in accordance with claim 7 wherein said ratio ranges from about 10:1 to about 30:1.
Claim 8
Dependent Claim
25 words
A process in accordance with claim 1 wherein said contacting is carried out by a continuous countercurrent contacting of said precipitated polycarbonate with said solvent.
References Cited (Backward Citations)
US3240755A
Cited
US3376261A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1975-06-06 | 1975-12-06 | 1976-06-06 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-06-06 | 1979-12-06 | 1980-06-06 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-06-06 | 1983-12-06 | 1984-06-06 | $7700.00 | Window Closed / Lapsed |