US4404370A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Purification of cellulose and starch ethers with counter current washing
Assignee: Bayer AG
•
Filing: 1982-11-23
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Granted: 1983-09-13
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Expires: 2002-11-23
Abstract
Abstract A process for the purification and isolation of cellulose or starch ethers wherein directly after the etherification step the suspension agent and the extraction of the ether product with the purifying agent is carried out on the same continuously working filter.
Inventors
- 👤 Claus-Rudiger Bernert
- 👤 Volker Hartwig
- 👤 Christian Kords
- 👤 Detmar Redeker
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-06 10:05
CPC Classifications
C; C08; C08B; C08B11/00; C08B11/20; C08B31/00; C08B31/08
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
82 words
A process for the continuous purification and isolation of a cellulose or starch ether suspension which comprises filtering off the suspension agent, extracting the reaction product with a purifying agent different from the suspension agent and drying it under suction, wherein directly after the etherification step without any intermediate drying and the preparation of pastes the suspension agent is filtered off and the reaction product is extracted in countercurrent with the purifying agent at least once on the same continuously working filter.
Claim 2
Dependent Claim
82 words
A process for the continuous purification and isolation of a cellulose or starch ether suspension which comprises filtering off the suspension agent, extracting the reaction product with a purifying agent different from the suspension agent and drying it under suction, wherein directly after the etherification step without any intermediate drying and the preparation of pastes the suspension agent is filtered off and the reaction product is extracted in countercurrent with the purifying agent at least once on the same continuously working filter.
Claim 3
Dependent Claim
24 words
A process as claimed in claim 1, wherein the filter is a band filter circulating at a speed of from 10 to 100 mm/s.
Claim 4
Dependent Claim
21 words
A process as claimed in claim 2, wherein the band filter circulates at a speed of from 15 to 40 mm/s.
Claim 5
Dependent Claim
26 words
A process as claimed in claim 1, wherein the purifying agent is a water/alcohol mixture with a water content of between 20% and 40% by weight.
Claim 6
Dependent Claim
30 words
A process as claimed in claim 1, wherein the purified cellulose or starch ether is also dried under suction at the same continuously working filter used for the purification step.
Claim 7
Dependent Claim
21 words
A process as claimed in claim 1, wherein the ratio of cellulose or starch ether to the purification agent is ≦1:10.
References Cited (Backward Citations)
US3498971A
Cited
DE2017454C3
Cited
US3873518A
Cited
US4048433A
Cited
US4229572A
Cited
US4296235A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1986-09-12 | 1987-03-14 | 1987-09-13 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1990-09-12 | 1991-03-14 | 1991-09-13 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1994-09-12 | 1995-03-14 | 1995-09-13 | $7700.00 | Window Closed / Lapsed |