Zimmer Aktiengesellschaft

Lurgi Zimmer Aktiengesellschaft

Instytut Wlokien Chemicznych

Gerhard Keunecke

Marco Belch

Juergen Wack

Henryk Struszczyk

Alojzy Urbanowski

Wlodzimierz Mikolajczyk

Pawel Starostka

Sabine Butzke

Adolf Arnold

The present invention comprises a process for the recovery from a reaction mixture of cellulose carbamate produced by conversion of cellulose with excess urea in an inert organic liquid reaction carrier, wherein the reaction mixture is treated with added water under heat, then the liquid phase is separated as much as possible on a filter, the cellulose carbamate remaining on the filter is washed with water, optionally pre-dried and, if desired, dried and recovered, and the organic reaction carrier is recovered by phase separation from the combined liquids.

Process for the recovery of cellulose carbamate

The invention is an apparatus for spinning solutions of cellulose carbamate by extruding the solution through a spinneret into a precipitation bath, coagulating the cellulose carbamate fibers thus formed and drawing off the fibers by mechanical means, where the fibers are enveloped from the outlet of the spinneret to the outlet of the precipitation bath in a stream of precipitating medium flowing in the same direction, where the velocity of flow of the precipitation medium where the fibers exit the spinneret (plane X,) amounts to 0.1 to 0.8 times the draw-off speed of the fibers, and the velocity of flow of the precipitation medium where the fibers exit the precipitation bath (plane X,) amounts to 0.96 to 1.1 times the draw-off speed of the fibers.

Device for spinning of solutions of cellulose carbamate

The invention is a process for spinning solutions of cellulose carbamate by extruding the solution through a spinneret into a precipitation bath, coagulating the cellulose carbamate fibers thus formed and drawing off the fibers by mechanical means, where the fibers are enveloped from the outlet from the spinneret to the outlet from the precipitation bath in a stream of precipitating medium flowing in the same direction, where the velocity of flow of the precipitation medium where the fibers exit the spinneret (plane X1) amounts to 0.1 to 0.8 times the draw-off speed of the fibers, and the velocity of flow of the precipitation medium where the fibers exit the precipitation bath (plane X3) amounts to 0.96 to 1.1 times the draw-off speed of the fibers.

Process for spinning of solutions of cellulose carbamate

A method for the manufacture of cellulose carbamate, whereby cellulose pulp is preliminarily activated by alkaline, hydrothermal and/or enzymatic treatment, then the activated cellulose pulp is mixed with aqueous urea solution, the water in the solution replaced with an organic reaction carrier, and thereafter the cellulose is reacted with urea in the liquid phase to yield cellulose carbamate, which is separated from the liquid medium and washed. The method results in uniform substitution and distribution of carbamate groups and in cellulose chain, which leads to good solubility of the cellulose carbamate in aqueous alkali solution as well as excellent spinnability for producing fibers, films, and other products.

Method for modified manufacture of cellulose carbamate

The invention comprises a process for producing cellulose carbamate with improved solubility properties comprising converting cellulose with urea in an inert, liquid, organic reaction carrier, at reaction temperature in the range of 80.degree. to 180.degree. C. where the reaction temperature is increased as the reaction time increases.

Production of cellulose carbamate with improved solubility properties

A process for the production of cellulose carbamate from cellulose and urea through the conversion of the cellulose with excess urea in an inert liquid organic reaction carrier at a temperature in the range of 130 .degree. to 160.degree. C., separation of the reaction carrier from the reaction mixture and washing of the reaction mixture with water. The cellulose is intimately mixed with an aqueous urea solution. Then the water in the solution is replaced with the organic reaction carrier, and the reaction of urea and cellulose is carried out in the presence of an inert gaseous carrier to remove the by-product ammonia. Thereafter, the organic reaction carrier remaining in the reaction product is replaced with an aqueous urea solution and the resulting suspension of cellulose carbamate in the urea solution is filtered and washed free of urea with water. No liquid ammonia is required in this process.

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Pulheim, Germany

Gerhard Keunecke