Cellulose pulp and shaped lyocell article having a reduced cellulose content

Abstract

The present invention describes special cellulose compositions that allow a lyocell fiber with a reduced cellulose content to be produced on a stable industrial scale, as well as the lyocell fiber produced from it.

1 . A pulp suitable for the production of shaped lyocell bodies, having a cellulose content of 90 wt. % or less and a hemicellulosis content of at least 7 wt. %, wherein a ratio of the C5/Xylan to C6/Mannan fraction (C5/C6 ratio) present in the hemicellulose is in the range from 125:1 to 1:3. 
     
     
         2 . The pulp of  claim 1 , wherein the C5/C6 ratio is in the range of 25:1 to 1:2. 
     
     
         3 . The pulp according to  claim 1 , wherein the proportion of hemicelluloses is 10% by weight or more. 
     
     
         4 . The pulp according to  claim 1 , wherein the hemicelluloses are present in a native state, have been chemically modified by processing processes or have been chemically modified or functionalized in a separate process step. 
     
     
         5 . The pulp according to  claim 1 , having a lignin content of more than 1% by weight. 
     
     
         6 . The pulp according to  claim 1 , wherein the cellulose content is further reduced by the presence of lignin, accessory constituents from the wood and/or the addition of metallic compounds. 
     
     
         7 . The pulp according to  claim 1 , having a xylan content of 9% by weight or more and/or a mannan content of 6% by weight or more. 
     
     
         8 . The Pulp according to  claim 7  having a xylan content of 9% or more by weight and a mannan content of 1% or less by weight. 
     
     
         9 . A lyocell shaped body prepared by using the pulp according to  claim 1 . 
     
     
         10 . The lyocell shaped body according to  claim 9 , wherein the shaped body is selected from fibers, filaments, staple fibers, nonwoven knitted fabrics, films and powders in spherical form. 
     
     
         11 . The lyocell shaped body according to  claim 9 , wherein the shaped body is a fiber, a filament or a staple fiber, having a cellulose content of less than 90% by weight, a hemicellulose content of more than 5% by weight and a C5/C6 ratio of 125:1 to 1:3. 
     
     
         12 . The lyocell shaped body according to  claim 9 , wherein the hemicellulose content is more than 10% by weight. 
     
     
         13 . The lyocell shaped body according to  claim 9 , wherein the shaped body is a fiber, a filament or a staple fiber with a WRV of greater than 70%. 
     
     
         14 . The lyocell shaped bodies  claim 9 , wherein the shaped body has a crystallinity of 40% or less. 
     
     
         15 . The lyocell shaped bodies  claim 9 , having a lignin content of more than 0% by weight up to 5% by weight. 
     
     
         16 . A process for producing a shaped lyocell body comprising dissolving a pulp having a cellulose content of 90 wt. % or less and a hemicelluloses content of at least 7 wt. %, wherein a ratio of C5/Xylan to C6/Mannan fraction (C5/C6 ratio) present in the hemicellulose is in the range of 125:1 to 1:3, in a suitable solvent, and forming the solution into a shaped lyocell body. 
     
     
         17 . The process according to  claim 16 , wherein the lyocell shaped body is obtained by a lyocell spinning process. 
     
     
         18 . A process for producing a pulp according to  claim 1 , said process comprising at least one of the following steps:
 a) Mixing a pure pulp with xylan and/or mannan;   b) Treating a pulp having a hemicellulose content including mannan by chemical and/or physical methods to modify the hemicellulose content and/or the composition of the hemicellulose contained therein;   c) Production of a pulp using coniferous and/or deciduous woods;   d) Mixing a mannan-free pulp with a hemicellulose-rich pulp and optionally subsequent chemical and/or physical treatment of the mixture to adjust the hemicellulose content and/or composition of the hemicellulose moiety;   e) Mixing two pulps having different hemicellulose content and/or hemicellulose composition, and optionally subsequent chemical and/or physical treatment of the mixture to adjust the hemicellulose content and/or the composition of the hemicellulose moiety.   
     
     
         19 . The method according to  claim 18 , wherein the different pulps are selected from hardwood and softwood based pulps. 
     
     
         20 . The lyocell shaped body according to  claim 11 , wherein the shaped body has a C5/C6 ratio of 25:1 to 1:2. 
     
     
         21 . The lyocell shaped body according to  claim 13 , having a WRV of greater than 75%. 
     
     
         22 . The lyocell shaped body according to  claim 21 , having a WRV of greater than 80%.