Patent US3897391A successfully refreshed from Google Patents.
US3897391A
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Process for preparing polycarbonate
Assignee: General Electric Co
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Filing: 1973-09-28
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Granted: 1975-07-29
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Expires: 1993-09-28
Abstract
Abstract An improved process for preparing an aromatic polycarbonate, which improvement comprises carrying out the reaction in the presence of a minor amount of a particular hypophosphite such as alkali earth metal or alkali metal hypophosphite and, in particular, sodium hypophosphite. The mere employing of the particular additive in the reaction medium results in a polycarbonate having improved resistance to thermal degradation.
Inventors
- 👤 Donald B G Jaquiss
- 👤 Howard E Munro
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 23:05
CPC Classifications
C; C08; C08G; C08G64/00; C08G64/20; C08G64/22; C08G64/24
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
69 words
IN A PROCESS FOR THE MANUFACTURE OF AN IMPROVED AROMATIC POLYCARBONATE BY REACTING A DIHYDRIC PHENOL WITH A CARBONATE PRECURSOR, THE IMPROVEMENT COMPRISING CARRYING OUT THE REACTION IN THE PRESENCE OF 0.01 - 5.0 WEIGHT % OF A HYPOPHOSPHITE SELECTED FROM THE GROUP CONSISTING OF ALKALI EARTH METAL HYPOPHOSPHITES AND ALKALI METAL HYPOPHOSPHITES, SAID WEIGHT % BEING BASED ON THE WEIGHT OF THE DIHYDRIC PHENOL EMPLOYED IN THE REACTION.
Claim 2
Dependent Claim
69 words
IN A PROCESS FOR THE MANUFACTURE OF AN IMPROVED AROMATIC POLYCARBONATE BY REACTING A DIHYDRIC PHENOL WITH A CARBONATE PRECURSOR, THE IMPROVEMENT COMPRISING CARRYING OUT THE REACTION IN THE PRESENCE OF 0.01 - 5.0 WEIGHT % OF A HYPOPHOSPHITE SELECTED FROM THE GROUP CONSISTING OF ALKALI EARTH METAL HYPOPHOSPHITES AND ALKALI METAL HYPOPHOSPHITES, SAID WEIGHT % BEING BASED ON THE WEIGHT OF THE DIHYDRIC PHENOL EMPLOYED IN THE REACTION.
Claim 3
Dependent Claim
31 words
The process of claim 1 wherein the reaction is carried out in a reaction medium consisting of an aqueous alkaline solution having a pH of 6-14 and an inert organic solvent.
Claim 4
Dependent Claim
11 words
The process of claim 1 wherein the hypophosphite is sodium hypophosphite.
Claim 5
Dependent Claim
15 words
The process of claim 2 wherein the pH of the aqueous alkaline solution is 9-13.
Claim 6
Dependent Claim
13 words
The process of claim 2 wherein the inert organic solvent is methylene chloride.
Claim 7
Dependent Claim
11 words
The process of claim 1 wherein the carbonate precursor is phosgene.
Claim 8
Dependent Claim
12 words
The process of claim 1 wherein the dihydric phenol is 2,2-bis(4-hydroxyphenyl) propane.
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) | 1978-07-28 | 1979-01-27 | 1979-07-29 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-07-28 | 1983-01-27 | 1983-07-29 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-07-28 | 1987-01-27 | 1987-07-29 | $7700.00 | Window Closed / Lapsed |