US4990595A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Process for lowering the melt viscosity of aromatic polycarbonates, aromatic polyester carbonates and aromatic and/or araliphatic polyesters with super-critical gases
Assignee: Bayer AG
•
Filing: 1989-08-15
•
Granted: 1991-02-05
•
Expires: 2009-08-15
Abstract
Abstract By treating aromatic polycarbonates, aromatic polyester carbonates and aromatic and/or araliphatic polyesters in the molten state with super-critical gases or gas mixtures under pressure, the melt viscosity of these polymers is considerably lowered so that basic chemical operations which proceed only incompletely under the usual conditions can be carried out on these thermoplasts.
Inventors
- 👤 Hans-Joachim Traechkner
- 👤 Karl-Dieter Lohr
- 👤 Wolfgang Wehnert
- 👤 Claus Wulff
- 👤 Wolfgang Arlt
- 👤 Hanns-Ingolf Paul
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 00:38
CPC Classifications
C; C08; C08G; C08G64/00; C08G64/40; B; B01; B01D; B01D29/00; B01D29/11; B01D29/117; B01D29/60; B01D29/606; B01D29/76; B01D29/80; B01D29/84; B01D29/846; B01D29/88; B01D29/90; B01D29/906; B01D29/92; B01D37/00; B01D37/03; C08G63/00; C08G63/88
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
43 words
Process for lowering the melt viscosity of aromatic polycarbonates, aromatic polyester carbonates or mixtures thereof with each other, characterised in that the polycarbonates, polyester carbonates, polyesters or mixtures thereof with each other are treated in the molten state with supercritical gases under pressure.
Claim 2
Dependent Claim
43 words
Process for lowering the melt viscosity of aromatic polycarbonates, aromatic polyester carbonates or mixtures thereof with each other, characterised in that the polycarbonates, polyester carbonates, polyesters or mixtures thereof with each other are treated in the molten state with supercritical gases under pressure.
Claim 3
Dependent Claim
29 words
Process as claimed in claim 1, characterised in that the polycarbonates, polyester carbonates, polyesters or mixtures thereof are treated with super-critical gases at temperatures from 30° to 450° C.
Claim 4
Dependent Claim
30 words
Process according to claim 1, characterised in that the polycarbonates, polyester carbonates, polyesters or mixtures thereof are treated with super-critical gases at a pressure of from 25 to 350 bar.
Claim 5
Dependent Claim
27 words
Process according to claim 1, characterised in that the super-critical gases are selected from carbon dioxide, dinitrogen monoxide, chlorofluorohydrocarbons, alkanes, cycloalkanes, alkenes, sulfur hexafluoride or mixtures thereof.
References Cited (Backward Citations)
US4252968A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1994-02-04 | 1994-08-06 | 1995-02-05 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1998-02-04 | 1998-08-06 | 1999-02-05 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2002-02-04 | 2002-08-06 | 2003-02-05 | $7700.00 | Window Closed / Lapsed |