US3989672A
Expired / Lapsed
US
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Process for preparing aromatic carbonate polymers
Assignee: General Electric Co
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Filing: 1974-09-23
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Granted: 1976-11-02
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Expires: 1994-09-23
Abstract
Abstract A process for preparing a polycarbonate having improved resistance to thermal degradation and improved impact resistance by reacting a carbonate precursor such as phosgene with a dihydric phenol such as bisphenol-A in an aqueous medium while adding sufficient alkali metal hydroxide to maintain a pH of between 8.0 and 10.2 during the entire reaction.
Inventors
- 👤 Jorgen Helm Vestergaard
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 07:30
CPC Classifications
C; C08; C08G; C08G64/00; C08G64/20; C08G64/22; C08G64/24
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
46 words
A process for preparing a carbonate polymer having improved resistance to thermal degradation and improved impact resistance, which process consists of reacting a carbonate precursor with 2,2-bis(4-hydroxyphenyl) propane in an aqueous medium containing sufficient alkali metal hydroxide to maintain a pH between 8.0-10.2 during the reaction.
Claim 2
Dependent Claim
46 words
A process for preparing a carbonate polymer having improved resistance to thermal degradation and improved impact resistance, which process consists of reacting a carbonate precursor with 2,2-bis(4-hydroxyphenyl) propane in an aqueous medium containing sufficient alkali metal hydroxide to maintain a pH between 8.0-10.2 during the reaction.
Claim 3
Dependent Claim
59 words
The process of claim 1 which consists of (a) mixing 2,2-bis(4-hydroxyphenyl) propane in an aqueous medium containing a solvent for the carbonate polymer, a molecular weight regulator and a catalyst, (b) introducing a carbonyl halide into the reaction medium and (c) adding simultaneously with the carbonyl halide sufficient alkali metal hydroxide to maintain a pH between 8.0 and 10.2.
Claim 4
Dependent Claim
11 words
The process of claim 2 wherein the carbonyl halide is phosgene.
Claim 5
Dependent Claim
13 words
The process of claim 2 wherein the alkali metal hydroxide is sodium hydroxide.
Claim 6
Dependent Claim
10 words
The process of claim 2 wherein the catalyst is triethylamine.
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) | 1979-11-02 | 1980-05-03 | 1980-11-02 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1983-11-02 | 1984-05-03 | 1984-11-02 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1987-11-02 | 1988-05-03 | 1988-11-02 | $7700.00 | Window Closed / Lapsed |