Method and device for producing post-stretched cellulose spun threads

Abstract

The invention relates to a method and device for producing Lyocell fibres from a spinning solution containing water, cellulose and tertiary amine oxide. The spinning solution is extruded to form spun threads ( 10 ). The spun threads ( 10 ) are stretched and passed through a precipitation bath ( 16 ) in order to precipitate the cellulose. It has been surprisingly revealed that the tenacity of the Lyocell fibres produced in this way can be increased when the stretched fibres are subjected to post-stretching in a post-stretching means. The post-stretched Lyocell fibres have a wet modulus of at least 260 cN/tex.

1 . Method for the production of Lyocell fibres from a spinning solution containing water, cellulose and tertiary amine oxide, the method comprising: 
 extrusion of the spinning solution to spun threads;    stretching of the spun threads;    passage of the spun threads through a precipitation bath; and    post-stretching and simultaneous heat treatment of the stretched spun threads after passage through the precipitation bath.    
   
   
       2 . Method according to  claim 1 , further comprising: 
 coagulation of the cellulose of the spun threads before stretching.    
   
   
       3 . Method according to  claim 1 , further comprising: 
 post-stretching with a tensile stress of at least 0.8 cN/tex.    
   
   
       4 . Method according to  claim 3 , further comprising: 
 post-stretching with a tensile stress of at least 3.5 cN/tex.    
   
   
       5 . Method according to  claim 1 , further comprising: 
 treatment of the spun threads during heat treatment with hot inert gas.    
   
   
       6 . Method according to  claim 1 , further comprising: 
 treatment of the spun threads during heat treatment with steam.    
   
   
       7 . Method according to  claim 1 , further comprising: 
 passage of the spun threads through an air gap before the precipitation bath.    
   
   
       8 . Method according to  claim 7 , further comprising: 
 blowing of the spun threads in the air gap with a flow of cooling gas.    
   
   
       9 . Method according to  claim 1 , further comprising: 
 conveyance of the spun threads free of tensile stress between the stretching and the post-stretching.    
   
   
       10 . Method according to  claim 1 , further comprising: 
 crimping of the post-stretched spun threads.    
   
   
       11 . Method according to  claim 1 , further comprising: 
 cutting of the post-stretched spun threads to form staple fibres.    
   
   
       12 . Device ( 1 ) for the manufacture of spun threads from a spinning solution containing cellulose, water and a tertiary amine oxide, with a spinneret, through which the spinning solution can be extruded in operation to form spun threads, with a precipitation bath with a precipitating agent to precipitate cellulose, through which the spinning threads are passed in operation, with a first stretching means, through which the spun threads can be stretched in operation, and with a second stretching means, through which the spun threads stretched by the first stretching means can be post-stretched in operation, and a heating device arranged in the region of the second stretching means and by which the spun threads can be heated in operation during the post-stretching, wherein the spun threads can be stretched by the first stretching means in an air gap before entering the precipitation bath.  
   
   
       13 . Lyocell fibre, in particular manufactured by the method according to  claim 1 , wherein a wet modulus of at least 250 cN/tex and by a wet abrasion number per 25 fibres of at least 18.  
   
   
       14 . Lyocell fibre according to  claim 13 , wherein a wet modulus of at least 300 cN/tex.  
   
   
       15 . Lyocell fibre according to  claim 14 , wherein a wet modulus of at least 350 cN/tex.  
   
   
       16 . Cellulose fibres according to  claim 13 , wherein a wet tensile force elongation of at the most 12%.  
   
   
       17 . Cellulose fibres according to  claim 13 , wherein a wet abrasion number per 25 fibres of at the most 25.