Patent US4268666A successfully refreshed from Google Patents.
US4268666A
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US
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Process for the dissolution of cellulose in organic solvents, solutions obtained by said process, and process for the production of formed bodies of regenerated cellulose from said solutions
Assignee: SNIA Viscosa SpA
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Filing: 1979-03-29
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Granted: 1981-05-19
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Expires: 1999-03-29
Abstract
Abstract A process for the dissolution of cellulose in organic solvents such as dihylformamide, dimethylacetamide, and N-methylpyrrolidone is described which comprises contacting the cellulose with an excess of paraformaldehyde and with the solvent at elevated temperatures, preferably higher than 115° C. The amount of paraformaldehyde used preferably corresponds to at least 13 CH 2 O units per anhydroglucosidic unit of the cellulose. The solution obtained can be rendered stable at room temperature by heating it under stirring to lower the paraformaldehyde content, preferably to not less than 8 CH 2 O units per anhydroglucosidic unit. Formed bodies of regenerated cellulose can be obtained from said solutions by coagulating them in an aqueous bath, which may be alkaline or may be a mixture of water and the solvent of the solution, or even by evaporating the solvent.
Inventors
- 👤 Alberto Baldini
- 👤 Roberto Leoni
- 👤 Angelo Calloni
- 👤 Gianfranco Angelini
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 23:34
CPC Classifications
C; C08; C08B; C08B1/00; C08B1/003; C08B16/00
Claims Analysis
Total Claims: 19
Claim 1
Independent Claim
39 words
A process for the dissolution of cellulose in a solvent selected from the group consisting of dimethylformamide, dimethylacetamide and N-methylpyrrolidone characterized in that the cellulose is contacted with an excess of paraformaldehyde and with said solvent at elevated temperatures.
Claim 2
Dependent Claim
39 words
A process for the dissolution of cellulose in a solvent selected from the group consisting of dimethylformamide, dimethylacetamide and N-methylpyrrolidone characterized in that the cellulose is contacted with an excess of paraformaldehyde and with said solvent at elevated temperatures.
Claim 3
Dependent Claim
29 words
A process according to claim 1, characterized in that the amount of paraformaldehyde used corresponds to at least 13 CH 2 O units per anydroglucosidic unit of the cellulose.
Claim 4
Dependent Claim
16 words
A process according to claim 1, characterized in that the temperature is higher than 115° C.
Claim 5
Dependent Claim
31 words
A process according to claim 1, characterized in that the cellulose and paraformaldehyde powder are suspended in the solvent and the suspension is heated in a closed vessel under efficient stirring.
Claim 6
Dependent Claim
19 words
A process according to claim 1, characterized in that the solution obtained is treated to lower its formaldehyde content.
Claim 7
Dependent Claim
40 words
A process according to claim 5, characterized in that the treatment to lower the formaldehyde content is discontinued before the amount of paraformaldehyde in the solution has decreased below 3 CH 2 O units per anhydroglucosidic unit of the cellulose.
Claim 8
Dependent Claim
23 words
A process according to claim 5, characterized in that the formaldehyde of the solution is reduced by venting the solution at elevated temperature.
Claim 9
Dependent Claim
44 words
A process according to claim 5, characterized in that the formaldehyde of the solution is reduced by producing, in a space communicating with the reaction space, a zone having a temperature lower than the reaction temperature, whereby to cause the condensation of the paraformaldehyde.
Claim 10
Dependent Claim
21 words
A process according to claim 8, characterized in that the lower temperature zone is produced by circulation of a cooling fluid.
Claim 11
Dependent Claim
49 words
A process according to claim 1 in which the solution is treated to lower the formaldehyde content by cooling the solution to form an opaque solution, and the resulting opaque solution is heated once more under stirring to temperatures close to the temperatures at which it has been formed.
Claim 12
Dependent Claim
15 words
A process according to claim 1, characterized in that dimethylsulphoxide is added to the solvent.
Claim 13
Dependent Claim
18 words
A process according to claim 1, characterized in that starting products are employed having a low moisture content.
Claim 14
Dependent Claim
31 words
A process according to claim 12 characterized in that the moisture content of the starting products is such as to determine a water content of the solution not higher than 0.5%.
Claim 15
Dependent Claim
23 words
A process according to claim 12, characterized in that the starting products are dried to reduce the water content to the desired value.
Claim 16
Dependent Claim
29 words
Solutions of cellulose derivatives in a solvent selected from the group consisting of dimethylformamide, dimethylacetamide and N-methylpyrrolidione, and containing paraformaldehyde in excess of the anhydroglucosidic units in said cellulose.
Claim 17
Dependent Claim
29 words
Solutions of cellulose derivatives in a solvent selected from the group consisting of dimethylformamide, dimethylacetamide and N-methylpyrrolidione, and containing paraformaldehyde in excess of the anhydroglucosidic units in said cellulose.
Claim 18
Dependent Claim
8 words
Solutions according to claim 15, additionally containing dimethylsulphoxide.
Claim 19
Dependent Claim
24 words
Solutions according to claim 16, wherein the amount of paraformaldehyde is at least 8 CH 2 O units per anhydroglucosidic unit of the cellulose.
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US4129451A
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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) | 1984-05-18 | 1984-11-17 | 1985-05-19 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1988-05-18 | 1988-11-17 | 1989-05-19 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1992-05-18 | 1992-11-17 | 1993-05-19 | $7700.00 | Window Closed / Lapsed |