US5410034A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Alkaline method for dissolving cellulose
Assignee: United States Department of Agriculture
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Filing: 1994-02-24
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Granted: 1995-04-25
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Expires: 2014-02-24
Abstract
Abstract The present invention provides a cellulose solution prepared by dissolving a cellulose which has not previously been subject to explosive disruption at atmospheric pressures in an aqueous alkali solution which can be shaped into a fiber, film or other article or applied to the surface or treatment of other materials by coating, dipping, or other suitable methods.
Inventors
- 👤 Akira Isogai
- 👤 Rajai H. Atalla
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 13:58
CPC Classifications
C; C08; C08B; C08B1/00; C08B1/08; C08B1/003
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
116 words
A method for dissolving cellulose at atmospheric pressures without prior explosive disruption comprising the steps of: (a) providing a dispersion of cellulose in an aqueous strong base solution wherein the cellulose material has a DP of at least about 350, wherein said alkali solution comprises from about 7% to about 12% by weight of said strong base, (b) freezing said cellulose dispersion to a temperatures sufficient to form a solid mass of said cellulose dispersion; (c) warming said solid mass of said cellulose dispersion to a temperature sufficient to thaw said solid mass of said cellulose dispersion to provide a cellulose solution wherein the cellulose is dissolved; and (d) diluting the thawed cellulose dispersion with water.
Claim 2
Independent Claim
116 words
A method for dissolving cellulose at atmospheric pressures without prior explosive disruption comprising the steps of: (a) providing a dispersion of cellulose in an aqueous strong base solution wherein the cellulose material has a DP of at least about 350, wherein said alkali solution comprises from about 7% to about 12% by weight of said strong base, (b) freezing said cellulose dispersion to a temperatures sufficient to form a solid mass of said cellulose dispersion; (c) warming said solid mass of said cellulose dispersion to a temperature sufficient to thaw said solid mass of said cellulose dispersion to provide a cellulose solution wherein the cellulose is dissolved; and (d) diluting the thawed cellulose dispersion with water.
Claim 3
Dependent Claim
25 words
A method in accordance with claim 1 wherein said strong base is selected from the group consisting of sodium hydroxide, potassium hydroxide and ammonium hydroxide.
Claim 4
Dependent Claim
14 words
A method in accordance with claim 1 wherein said strong base is sodium hydroxide.
Claim 5
Dependent Claim
28 words
A method in accordance with claim 1 wherein said cellulose is present in said cellulose dispersion at a level of from about 0.1% to about 15% by weight.
Claim 6
Dependent Claim
20 words
A method in accordance with claim 1 wherein said cellulose has a DP of from about 350 to about 2000.
Claim 7
Dependent Claim
39 words
A method in accordance with claim 1 wherein said dilution with water is sufficient to provide a cellulose solution having from about 0.1% to about 15% of cellulose and from about 4% to about 7% of said sodium hydroxide.
Claim 8
Dependent Claim
26 words
A method in accordance with claim 1 wherein the temperature in step (b) is in the range of from about -10° C. to about -30° C.
Claim 9
Dependent Claim
22 words
A method in accordance with claim 1 wherein the temperature in step (c) is from about 20° C. to about 30° C.
References Cited (Backward Citations)
DE260187C
Cited
US2638415A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1998-04-24 | 1998-10-24 | 1999-04-25 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2002-04-24 | 2002-10-24 | 2003-04-25 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2006-04-24 | 2006-10-24 | 2007-04-25 | $7700.00 | Window Closed / Lapsed |