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Verfahren zur Herstellung von Cellulosecarbamat mittels reaktiver Extrusion

Production of cellulose carbamate, for molding e.g. to fibers, film, beads, sponge or sponge cloth, involves activating cellulose in aqueous alkali hydroxide solution containing urea, separation from solution and reactive extrusion.
: Loth, F.; Fink, H.; Weigel, P.

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DE 2002-10223172 A: 20020524
DE 2002-10223172 A: 20020524
WO 2003-EP4880 A: 20030509
EP 2003-732337 AW: 20030509
DE 10223172 A1: 20031211
EP 1511773 A1: 20050309
Patent, Elektronische Publikation
Fraunhofer IAP ()

Die Erfindung betrifft ein Verfahren zur Herstellung von Cellulosecarbamat durch reaktive Extrusion sowie zur Herstellung von Formkoerpern aus Regeneratcellulose. Das Verfahren zur Herstellung von Cellulosecarbamat basiert dabei auf der Aktivierung der Cellulose, der anschliessenden Abtrennung der Aktivierungsloesung und der sich anschliessenden reaktiven Extrusion der aktivierten Cellulose. Typische Beispiele fuer hieraus herstellbare Formkoerper sind Fasern, Folien, Perlen, Schwaemme oder Schwammtuecher.


WO2003099872 A UPAB: 20040115 NOVELTY - Production of cellulose carbamate (I) comprises (a) activating cellulose with an activation solution of urea in aqueous alkali hydroxide solution; (b) separating the activation solution from the cellulose; and (c) reactive extrusion of the activated cellulose at 180-280 deg. C, with removal of the ammonia gas liberated to the equilibrium. DETAILED DESCRIPTION - An INDEPENDENT CLAIM is also included for cellulose carbamate produced by this process. USE - The process is used for producing moldings from cellulose carbamate and/or regenerated cellulose by making the cellulose into a spinning solution with aqueous alkali hydroxide solution and spinning this through spinnerets into a precipitation bath, especially for making fibers, films, beads, sponge and sponge cloths (all claimed). ADVANTAGE - Cellulose carbamates provide an alternative to the viscose process for producing regenerated cellulose fibers. However, impregnation with urea and activation with liquid ammonia (which is costly) or impregnation with aqueous sodium hydroxide solution and then aqueous urea gives a product with inhomogeneous substitution and also requires reaction times of about 2 hours at 130-150 deg. C. The present process avoids these drawbacks. It is suitable for continuous operation and gives homogeneous distribution of substituents, hence good product quality. It also reduces capital and operating costs and environmental pollution.