Patent US4302252A successfully refreshed from Google Patents.
US4302252A
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Solvent system for cellulose
Assignee: Rayonier Inc
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Filing: 1980-04-30
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Granted: 1981-11-24
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Expires: 2000-04-30
Abstract
Abstract Cellulose is activated by penetration of the cellulose with a polar medium and mixed at a temperature at which no significant degradation occurs with an amide selected from the group consisting of dimethylacetamide, 1-methyl-2-pyrrolidinone and mixtures thereof and from 3 to 15% by weight of lithium chloride. The cellulose is then dissolved in the amide and lithium chloride in the substantial absence of any polar medium other than the amide. Shaped cellulosic products may be formed by reconstituting the cellulose in fiber, sheet or other form.
Inventors
- 👤 Albin F. Turbak
- 👤 Adel El-Kafrawy
- 👤 Fred W. Snyder, Jr.
- 👤 Andrew B. Auerbach
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 05:31
CPC Classifications
C; C08; C08J; C08J3/00; C08J3/02; C08J3/09; C08J3/091; C08J3/096; C08B; C08B1/00; C08B1/003; C08K; C08K3/00; C08K3/16; C08J2301/00; C08J2301/02
Claims Analysis
Total Claims: 30
Claim 1
Independent Claim
71 words
A process of dissolving cellulose comprising mixing activated cellulose at a temperature at which no significant degradation occurs with an amide selected from the group consisting of dimethylacetamide, 1-methyl-2-pyrrolidinone and mixtures thereof and from 3 to 12% by weight of the solution of lithium chloride and dissolving said cellulose without significant degradation thereof in said amide and lithium chloride in the substantial absence of any polar medium other than the amide.
Claim 2
Dependent Claim
71 words
A process of dissolving cellulose comprising mixing activated cellulose at a temperature at which no significant degradation occurs with an amide selected from the group consisting of dimethylacetamide, 1-methyl-2-pyrrolidinone and mixtures thereof and from 3 to 12% by weight of the solution of lithium chloride and dissolving said cellulose without significant degradation thereof in said amide and lithium chloride in the substantial absence of any polar medium other than the amide.
Claim 3
Dependent Claim
36 words
The process of claim 1 in which the cellulose is activated by penetration with a polar medium which swells the cellulose, which polar medium, other than the amide, is removed prior to dissolution of the cellulose.
Claim 4
Dependent Claim
18 words
The process of claim 1 in which activation of the cellulose is aided by microfibrillation of the cellulose.
Claim 5
Dependent Claim
17 words
The process of claim 2 in which the polar medium is a liquid which swells the cellulose.
Claim 6
Dependent Claim
22 words
The process of claim 2 in which the polar medium is exchanged with a medium less polar than water prior to dissolution.
Claim 7
Dependent Claim
24 words
The process of claim 4 in which the polar medium is a liquid selected from the group consisting of water, ammonia, dimethylacetamide and dimethylsulfoxide.
Claim 8
Dependent Claim
13 words
The process of claim 2 in which the polar medium is dimethylacetamide vapor.
Claim 9
Dependent Claim
12 words
The process of claim 6 in which the polar liquid is water.
Claim 10
Dependent Claim
24 words
The process of claim 1 in which the activated cellulose is cellulosic pulp from which the water has not been removed subsequent to pulping.
Claim 11
Dependent Claim
22 words
The process of claim 9 in which the water in the cellulose pulp is exchanged with a non-swelling liquid prior to dissolution.
Claim 12
Dependent Claim
19 words
The process of claim 2 in which the cellulose is cellulosic pulp which has been dried prior to activation.
Claim 13
Dependent Claim
17 words
The process of claim 1 in which dissolution occurs at a temperature of less than 150° C.
Claim 14
Dependent Claim
12 words
The process of claim 1 in which dissolution occurs at room temperature.
Claim 15
Dependent Claim
11 words
The process of claim 1 in which the amide is dimethylacetamide.
Claim 16
Dependent Claim
59 words
The process of claim 1 in which the cellulose is added to the amide in the absence of the lithium chloride, the mixture of cellulose and amide is heated to a temperature of at least 150° C., the mixture is cooled to less than 100° C., the lithium chloride is added and the mixture stirred until solution is complete.
Claim 17
Dependent Claim
71 words
A process of dissolving cellulose comprising adding at a temperature at which no significant degradation occurs activated cellulose to an amide selected from the group consisting of dimethylacetamide, 1-methyl-2-pyrrolidinone and mixtures thereof and from 3 to 12% by weight of the solution of lithium chloride and dissolving said cellulose without significant degradation thereof in said amide and lithium chloride in the substantial absence of any polar medium other than the amide.
Claim 18
Dependent Claim
71 words
A process of dissolving cellulose comprising adding at a temperature at which no significant degradation occurs activated cellulose to an amide selected from the group consisting of dimethylacetamide, 1-methyl-2-pyrrolidinone and mixtures thereof and from 3 to 12% by weight of the solution of lithium chloride and dissolving said cellulose without significant degradation thereof in said amide and lithium chloride in the substantial absence of any polar medium other than the amide.
Claim 19
Dependent Claim
86 words
A process for dissolving cellulose comprising activating cellulose by penetrating the cellulose with a polar medium which swells the cellulose, adding at a temperature at which no significant degradation of the cellulose occurs up to 16% by weight of said activated cellulose to an amide selected from the group consisting of dimethylacetamide, 1-methyl-2-pyrrolidinone and mixtures thereof and from 3 to 15% by weight of the solution of lithium chloride and stirring said mixture to form a solution of the cellulose in said amide and lithium chloride.
Claim 20
Dependent Claim
86 words
A process for dissolving cellulose comprising activating cellulose by penetrating the cellulose with a polar medium which swells the cellulose, adding at a temperature at which no significant degradation of the cellulose occurs up to 16% by weight of said activated cellulose to an amide selected from the group consisting of dimethylacetamide, 1-methyl-2-pyrrolidinone and mixtures thereof and from 3 to 15% by weight of the solution of lithium chloride and stirring said mixture to form a solution of the cellulose in said amide and lithium chloride.
Claim 21
Dependent Claim
17 words
The process of claim 17 in which dissolution occurs at a temperature of less than 150° C.
Claim 22
Dependent Claim
78 words
A process of dissolving cellulose to form a solution of cellulose in a solvent comprising adding at a temperature at which no significant degradation occurs cellulose to a solution containing an amide selected from the group consisting of dimethylacetamide, 1-methyl-2-pyrrolidinone and mixtures thereof, from 3 to 15% by weight of lithium chloride and water, evaporating the water from said solution until the solution contains less than 5% by weight of water and dissolving the cellulose in said solution.
Claim 23
Dependent Claim
78 words
A process of dissolving cellulose to form a solution of cellulose in a solvent comprising adding at a temperature at which no significant degradation occurs cellulose to a solution containing an amide selected from the group consisting of dimethylacetamide, 1-methyl-2-pyrrolidinone and mixtures thereof, from 3 to 15% by weight of lithium chloride and water, evaporating the water from said solution until the solution contains less than 5% by weight of water and dissolving the cellulose in said solution.
Claim 24
Dependent Claim
27 words
A cellulosic solution containing cellulose, from 3-15% by weight of the solution of lithium chloride and an amide selected from the group consisting of dimethylacetamide and 1-methyl-2-pyrrolidinone.
Claim 25
Dependent Claim
27 words
A cellulosic solution containing cellulose, from 3-15% by weight of the solution of lithium chloride and an amide selected from the group consisting of dimethylacetamide and 1-methyl-2-pyrrolidinone.
Claim 26
Dependent Claim
24 words
The solution of claim 20 containing up to 5% by weight of a polar medium, other than an amide, having an active hydrogen atom.
Claim 27
Dependent Claim
36 words
The solution of claim 21 in which the cellulose is present in an amount up to 16% and the lithium chloride in an amount from 5 to 12%, both by weight based on total solution weight.
Claim 28
Dependent Claim
59 words
A process of dissolving cellulose comprising mixing activated cellulose at a temperature at which no significant degradation occurs with an amide selected from the group consisting of dimethylacetamide, 1-methyl-2-pyrrolidinone and mixtures thereof and from 3 to 15% by weight of the solution of lithium chloride and dissolving said cellulose without significant degradation thereof in said amide and lithium chloride.
Claim 29
Dependent Claim
59 words
A process of dissolving cellulose comprising mixing activated cellulose at a temperature at which no significant degradation occurs with an amide selected from the group consisting of dimethylacetamide, 1-methyl-2-pyrrolidinone and mixtures thereof and from 3 to 15% by weight of the solution of lithium chloride and dissolving said cellulose without significant degradation thereof in said amide and lithium chloride.
Claim 30
Dependent Claim
32 words
The process of claim 1 in which dissolution occurs in the presence of no more than 5% by weight of a polar medium, other than an amide, having an active hydrogen atom.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1984-11-23 | 1985-05-25 | 1985-11-24 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1988-11-23 | 1989-05-25 | 1989-11-24 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1992-11-23 | 1993-05-25 | 1993-11-24 | $7700.00 | Window Closed / Lapsed |