US4022944A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Non-porous polycarbonate films less than 1 μm thick
Assignee: Bayer AG
•
Filing: 1976-03-15
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Granted: 1977-05-10
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Expires: 1996-03-15
Abstract
Abstract Non-porous, thin, polycarbonate films and a process for their production. Solutions of polycarbonates in concentrations of less than 5 parts solids per 100 parts solvent are applied to the surface of liquids immiscible, or sparingly miscible with, the solvent for the polycarbonate. The solvent is then evaporated, and the resultant film removed. The films are useful for the separation of gas and liquid mixtures and for electrical insulating purposes.
Inventors
- 👤 Ludwig Bottenbruch
- 👤 Gunther Kampf
- 👤 Volker Serini
- 👤 Hugo Vernaleken
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 16:17
CPC Classifications
B; B01; B01D; B01D71/00; B01D71/06; B01D71/50; B01D69/00; B01D69/12; B01D69/122; B29; B29D; B29D7/00; B29D7/01; Y; Y10; Y10T; Y10T428/00; Y10T428/31504; Y10T428/31507
Claims Analysis
Total Claims: 2
Claim 1
Independent Claim
25 words
Non-porous polycarbonate films based on aromatic polycarbonates from 2,2-bis-(3,5-dimethyl-4-hydroxyphenyl)-propane having molecular weights, M w , greater than 20,000 and having thicknesses less than 1 μm.
Claim 2
Dependent Claim
25 words
Non-porous polycarbonate films based on aromatic polycarbonates from 2,2-bis-(3,5-dimethyl-4-hydroxyphenyl)-propane having molecular weights, M w , greater than 20,000 and having thicknesses less than 1 μm.
References Cited (Backward Citations)
US3975225A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1980-05-09 | 1980-11-08 | 1981-05-10 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1984-05-09 | 1984-11-08 | 1985-05-10 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1988-05-09 | 1988-11-08 | 1989-05-10 | $7700.00 | Window Closed / Lapsed |