US4015611A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Cigarette filter
Assignee: Hoechst AG
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Filing: 1975-03-26
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Granted: 1977-04-05
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Expires: 1995-03-26
Abstract
Abstract This invention relates to a cigarette filter of cellulosic material composed at least partially of cellulose modified with an organic isocyanate or with higher molecular weight fatty acid groups, or of a naturally water-soluble cellulose ether rendered largely or completely insoluble in water by cross-linking or other means of modification, but still capable of adsorbing water.
Inventors
- 👤 Arno Holst
- 👤 Michael Kostrzewa
- 👤 Helmut Lask
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 15:32
CPC Classifications
A; A24; A24D; A24D3/00; A24D3/06; A24D3/08; A24D3/10
Claims Analysis
Total Claims: 3
Claim 1
Independent Claim
61 words
A cigarette filter of cellulosic material composed at least partially of a cellulose ether prepared by etherifying it to a virtually completely water-soluble cellulose ether and cross-linking said cellulose ether to a degree such that more than 50 percent by weight thereof is no longer soluble in water, but still capable of absorbing water to at least its own dry weight.
Claim 2
Dependent Claim
61 words
A cigarette filter of cellulosic material composed at least partially of a cellulose ether prepared by etherifying it to a virtually completely water-soluble cellulose ether and cross-linking said cellulose ether to a degree such that more than 50 percent by weight thereof is no longer soluble in water, but still capable of absorbing water to at least its own dry weight.
Claim 3
Dependent Claim
97 words
A cigarette filter of cellulosic material according to claim 1 composed at last partially of a cellulose ether cross-linked with a substance selected from the group consisting of epichlorohydrin, dichloro acetic acid, phosphorous oxychloride and a compound containing a group functional towards cellulose selected from ##STR3## said cellulose ether being prepared by etherifying it to a virtually completely water-soluble cellulose ether and cross-linking said cellulose ether to a degree such that more than 50 percent by weight thereof is no longer soluble in water, but still capable of absorbing water to at least its own dry weight.
References Cited (Backward Citations)
US2968306A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1980-04-04 | 1980-10-04 | 1981-04-05 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1984-04-04 | 1984-10-04 | 1985-04-05 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1988-04-04 | 1988-10-04 | 1989-04-05 | $7700.00 | Window Closed / Lapsed |