Cyclic process for producing an alkali solution of cellulose carbamate and precipitating the carbamate
US4639514A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Sep 24, 1985 |
| Grant date | Jan 27, 1987 |
| Priority date | — |
| Expiry date | Sep 24, 2005 |
Classification
- Technology area (CPC D)Textiles; Paper
- CPC primaryD01F2/24
- WIPO fieldMacromolecular chemistry, polymers
- WIPO sectorChemistry
Abstract
The present invention concerns a cyclic process for producing an alkali solution of cellulose carbamate, for precipitating the cellulose carbamate from the alkali solution and for recovering and recycling the chemicals. The process comprises the following steps: (a) an alkali solution of cellulose carbamate is prepared by dissolving cellulose carbamate in an aqueous solution of sodium hydroxide, (b) the solution obtained in step (a) is extruded into contact with a precipitating solution containing sodium carbonate, whereby the cellulose carbamate is precipitated and can be separated from the solution, (c) into the solution obtained in step (b) carbon dioxide is conducted for transforming the sodium hydroxide into sodium carbonate, (d) the solution obtained in step (c) is treated with calcium oxide, whereby the sodium carbonate is transformed into sodium hydroxide, and calcium carbonate precipitates from the solution, (e) solution containing sodium hydroxide obtained in step (d) is returned to step (a) for dissolving cellulose carbamate, and (f) calcium carbonate obtained in step (d) is decomposed into carbon dioxide and calcium oxide and the calcium oxide is returned to step (d).
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.