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US4020045A
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Process for controlling the molecular weight of aromatic polycarbonates
Assignee: Dow Chemical Co
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Filing: 1976-02-26
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Granted: 1977-04-26
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Expires: 1996-02-26
Abstract
Abstract Process for the preparation of aromatic polycarbonates by the interfacial technique wherein the molecular weight is controlled by adding an effective amount of metallic sulfites to the polymerization reaction. The metallic sulfites are exemplified by alkali metal sulfites, pyrosulfites and hyposulfites.
Inventors
- 👤 Joseph M. Baggett
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 15:41
CPC Classifications
C; C08; C08G; C08G64/00; C08G64/04; C08G64/06; C08G64/14; C08G64/20; C08G64/22; C08G64/24
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
80 words
A process for controlling the molecular weight of thermoplastic aromatic polycarbonates having hydroxyl terminated end groups which comprises reacting under interfacial polycarbonate-forming conditions 1. a carbonyl halide, 2. a dihydric phenol or mixtures of dihydric phenols, 3. a catalyst useful to form polycarbonates and 4. a chain terminating amount of a compound having one of the formulas ##STR8## wherein M 1 is a metal of Group IA, M 2 is a metal of Group IIA, R is ##STR9## or --O--.
Claim 2
Dependent Claim
80 words
A process for controlling the molecular weight of thermoplastic aromatic polycarbonates having hydroxyl terminated end groups which comprises reacting under interfacial polycarbonate-forming conditions 1. a carbonyl halide, 2. a dihydric phenol or mixtures of dihydric phenols, 3. a catalyst useful to form polycarbonates and 4. a chain terminating amount of a compound having one of the formulas ##STR8## wherein M 1 is a metal of Group IA, M 2 is a metal of Group IIA, R is ##STR9## or --O--.
Claim 3
Dependent Claim
40 words
The process as set forth in claim 1 wherein the amount of chain terminator compound used is such that the weight percent range of chain terminator to the dihydric phenol is in the range from about 1.0 to about 25.
Claim 4
Dependent Claim
31 words
The process as set forth in claim 2 wherein the chain terminating compound has the formula ##STR10## wherein M 1 is a metal of Group IA, R is ##STR11## or --O--.
Claim 5
Dependent Claim
39 words
The process as set forth in claim 3 wherein the amount of chain terminator used is such that the weight percent range of chain terminator to the dihydric phenol is in the range from about 3 to about 15.0.
Claim 6
Dependent Claim
18 words
The process as set forth in claim 4 wherein the chain terminating compound is an alkali metal sulfite.
Claim 7
Dependent Claim
14 words
The process as set forth in claim 5 wherein the compound is sodium sulfite.
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) | 1980-04-25 | 1980-10-25 | 1981-04-26 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1984-04-25 | 1984-10-25 | 1985-04-26 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1988-04-25 | 1988-10-25 | 1989-04-26 | $7700.00 | Window Closed / Lapsed |