Patent US3859245A successfully refreshed from Google Patents.
US3859245A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Process for the production of polycarbonate solutions
Assignee: Bayer AG
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Filing: 1973-02-16
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Granted: 1975-01-07
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Expires: 1993-02-16
Abstract
Abstract The invention is related to the production of the solution of a high molecular weight polycarbonate having a molecular weight above 30,000 suitable for the production of films and filaments. The process comprises subjecting the solid polycarbonates solutions obtained by solvent removal from polycarbonate solutions at temperatures below the melting point of said polycarbonate coupled with the application of shear energy for 0.1 to 50 hours to a solvent atmosphere of solvents which are able to dissolve polycarbonates and subsequently redissolving the thus obtained products.
Inventors
- 👤 Werner Stieler
- 👤 Rolf Oelmeyer
- 👤 Heinrich Haupt
- 👤 Hugo Vernaleken
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 20:17
CPC Classifications
C; C08; C08G; C08G64/00; C08G64/40
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
112 words
A process for the production of a solution of a high molecular weight polycarbonate having a molecular weight above 30,000 and an increased crystallinity, suitable for the production of films and filaments, which comprises (1) preparing a solid polycarbonate solution by removing solvent from a solution of a polycarbonate, derived from an aromatic dihydroxy compound, at a temperature below the melting point of said polycarbonate while applying shear energy to said polycarbonate, (2) subjecting said solid polycarbonate solution over a period of 0.1 to 50 hours to an atmosphere of a solvent for said polycarbonate, (3) recovering said polycarbonate with an increased crystallinity, and (4) redissolving said polycarbonate with an increased crystallinity.
Claim 2
Dependent Claim
112 words
A process for the production of a solution of a high molecular weight polycarbonate having a molecular weight above 30,000 and an increased crystallinity, suitable for the production of films and filaments, which comprises (1) preparing a solid polycarbonate solution by removing solvent from a solution of a polycarbonate, derived from an aromatic dihydroxy compound, at a temperature below the melting point of said polycarbonate while applying shear energy to said polycarbonate, (2) subjecting said solid polycarbonate solution over a period of 0.1 to 50 hours to an atmosphere of a solvent for said polycarbonate, (3) recovering said polycarbonate with an increased crystallinity, and (4) redissolving said polycarbonate with an increased crystallinity.
Claim 3
Dependent Claim
15 words
A process as claimed in claim 1, wherein methylene chloride is used as the solvent.
Claim 4
Dependent Claim
21 words
A process as claimed in claim 1, wherein a polycarbonate based on 4,4''-dihydroxy-diphenyl-2,2-propane is used as the high molecular weight polycarbonate.
Claim 5
Dependent Claim
35 words
A process as claimed in claim 1, wherein a copolycarbonate based on 95 to 99.8 mol parts of 4,4''-dihydroxy-diphenyl-2,2-propane and 5 to 0.2 mol parts of 1,4-bis-(4''-hydroxyphenyl-isopropylidene)-benzene is used as the high molecular weight polycarbonate.
Claim 6
Dependent Claim
15 words
The process of claim 1 wherein said atmosphere is a mixture of solvent and water-vapor.
Claim 7
Dependent Claim
28 words
THE PROCES OF CLAIM 1 WHEREIN SAID SOLID POLYCARBONATE SOLUTION, IN THE FORM OF A FLUIDIZED BED OF GRANULAR MATERIAL, IS SUBJECTED TO A FLOWING STREAM OF SOLVENT.
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) | 1978-01-06 | 1978-07-08 | 1979-01-07 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-01-06 | 1982-07-08 | 1983-01-07 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-01-06 | 1986-07-08 | 1987-01-07 | $7700.00 | Window Closed / Lapsed |