Patent US4294953A successfully refreshed from Google Patents.
US4294953A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Process for preparing a branched polycarbonate
Assignee: General Electric Co
•
Filing: 1979-05-31
•
Granted: 1981-10-13
•
Expires: 1999-05-31
Abstract
Abstract A process for preparing a thermoplastic, randomly branched aromatic polycarbonate is disclosed which comprises reacting a carbonate precursor, a dihydric phenol, and a dianhydride branching agent and maintaining the resultant reaction medium at a pH of from about 9 to about 12 to thereby produce a thermoplastic randomly branched aromatic polycarbonate.
Inventors
- 👤 Clayton B. Quinn
- 👤 William Hilakos
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 23:34
CPC Classifications
C; C08; C08G; C08G64/00; C08G64/04; C08G64/06; C08G64/14
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
45 words
A process for producing a thermoplastic, randomly branched polycarbonate substantially free of cross-linking which consists essentially of reacting, at a pH of about 9 to 12, a carbonate precursor, a dihydric phenol, and a dianhydride branching agent, to thereby produce a thermoplastic randomly branched polycarbonate.
Claim 2
Dependent Claim
45 words
A process for producing a thermoplastic, randomly branched polycarbonate substantially free of cross-linking which consists essentially of reacting, at a pH of about 9 to 12, a carbonate precursor, a dihydric phenol, and a dianhydride branching agent, to thereby produce a thermoplastic randomly branched polycarbonate.
Claim 3
Dependent Claim
30 words
The process of claim 1 wherein the dianhydride branching agent is selected from the group consisting of 1,2,3,4-tetracarboxybutane dianhydride, benzophenone tetracarboxylic acid dianhydride, 4,4'-[2,2-bis(4-hydroxyphenyl)propane]-dianhydride, and pyromellitic dianhydride or mixtures thereof.
Claim 4
Dependent Claim
27 words
The process of claim 1 wherein the dianhydride is employed in an amount of at least 0.05 mole percent, based on the total moles of dihydric phenol.
Claim 5
Dependent Claim
64 words
A process for producing a thermoplastic, randomly branched polycarbonate which comprises reacting, at a pH of about 9 to 12, a carbonate precursor, a dihydric phenol and at least 0.05 mole percent, based upon the total moles of dihydric phenol, of a dianhydride branching agent selected from the group consisting of 1,2,3,4-tetracarboxybutane dianhydride, benzophenone tetracarboxylic acid dianhydride, 4,4'-[2,2-bis(4-hydroxyphenyl)propane]-dianhydride, and pyromellitic dianhydride or mixtures thereof.
Claim 6
Dependent Claim
64 words
A process for producing a thermoplastic, randomly branched polycarbonate which comprises reacting, at a pH of about 9 to 12, a carbonate precursor, a dihydric phenol and at least 0.05 mole percent, based upon the total moles of dihydric phenol, of a dianhydride branching agent selected from the group consisting of 1,2,3,4-tetracarboxybutane dianhydride, benzophenone tetracarboxylic acid dianhydride, 4,4'-[2,2-bis(4-hydroxyphenyl)propane]-dianhydride, and pyromellitic dianhydride or mixtures thereof.
Claim 7
Dependent Claim
11 words
The process of claim 4 wherein the dihydric phenol is bisphenol-A.
Claim 8
Dependent Claim
11 words
The process of claim 4 wherein the carbonate precursor is phosgene.
Claim 9
Dependent Claim
31 words
The process of claim 4 wherein the dianhydride is employed in an amount of from about 0.2 mole percent to about 0.45 mole percent, based on the moles of dihydric phenol.
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) | 1984-10-12 | 1985-04-13 | 1985-10-13 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1988-10-12 | 1989-04-13 | 1989-10-13 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1992-10-12 | 1993-04-13 | 1993-10-13 | $7700.00 | Window Closed / Lapsed |