Patent US4371691A successfully refreshed from Google Patents.
US4371691A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Preparation of polycarbonate from specific crude bisphenols
Assignee: Bayer AG
•
Filing: 1980-07-09
•
Granted: 1983-02-01
•
Expires: 2000-07-09
Abstract
Abstract This disclosure relates to the processes for producing polycarbonates from specific crude bisphenols. The bisphenols are characterized in that immediately after their preparation they are subjected to (i) separation, of excess phenols and low-boiling substances, by means of an evaporator, and (ii) removal of monophenols by desorption. The invention also relates to high-molecular weight aromatic polycarbonates made of crude bisphenols and their use in a variety of applications.
Inventors
- 👤 Gerhard Friedhofen
- 👤 Volker Serini
- 👤 Rainer Neumann
- 👤 Dieter Freitag
- 👤 Hans-Helmut Schwarz
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 18:54
CPC Classifications
C; C08; C08G; C08G64/00; C08G64/20; C08G64/22; C08G64/24; C07; C07C; C07C37/00; C07C37/11; C07C37/20; C07C37/68; C07C37/70; C07C37/74; C08G64/04; C08G64/06; C08L; C08L69/00
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
92 words
In the process for the preparation of a thermoplastic, aromatic, high-molecular weight polycarbonate from at least one crude bisphenol, the improvement comprising: (i) separating said at least one crude bisphenol, immediately after its preparation, from excess of at least one phenol and low boiling substance, in an evaporator at a temperature between 100° and 300° C., and under a pressure of between 0.05 and 1000 millibars, and (ii) subjecting said crude bisphenol to desorption using an inert gas to attain a presence therein of monophenols of less than 2.5 percent by weight.
Claim 2
Dependent Claim
92 words
In the process for the preparation of a thermoplastic, aromatic, high-molecular weight polycarbonate from at least one crude bisphenol, the improvement comprising: (i) separating said at least one crude bisphenol, immediately after its preparation, from excess of at least one phenol and low boiling substance, in an evaporator at a temperature between 100° and 300° C., and under a pressure of between 0.05 and 1000 millibars, and (ii) subjecting said crude bisphenol to desorption using an inert gas to attain a presence therein of monophenols of less than 2.5 percent by weight.
Claim 3
Dependent Claim
15 words
The process according to claim 1 wherein said temperature is between 150° and 250° C.
Claim 4
Dependent Claim
15 words
The process according to claim 1 wherein said pressure is between 0.5 and 500 millibars.
Claim 5
Dependent Claim
19 words
The process according to claim 1 wherein said at least one crude bisphenol has at least 2 alkyl substituents.
Claim 6
Dependent Claim
19 words
The process according to claim 1 wherein said at least one crude bisphenol has at least 4 alkyl substituents.
Claim 7
Dependent Claim
19 words
The process in accordance with claim 1 wherein said presence of monophenols is less than 0.5 percent by weight.
References Cited (Backward Citations)
US3219549A
Cited
US2191831A
Cited
US2845464A
Cited
US3242219A
Cited
US3112292A
Cited
US3049568A
Cited
US3073868A
Cited
US3213060A
Cited
US3335111A
Cited
US3267075A
Cited
US3410823A
Cited
US3394089A
Cited
US3437639A
Cited
US3673262A
Cited
US3668181A
Cited
US4169211A
Cited
US3936507A
Cited
GB1410750A
Cited
GB1521605A
Cited
US4212774A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1986-01-31 | 1986-08-02 | 1987-02-01 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1990-01-31 | 1990-08-02 | 1991-02-01 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1994-01-31 | 1994-08-02 | 1995-02-01 | $7700.00 | Window Closed / Lapsed |