Process for producing cellulose multi-filament with lower coefficient of variation of section diameter

Abstract

The present invention relates to a cellulose fiber having a highly homogeneous section, particularly to a cellulose fiber with lower Coefficient of Variation of section diameter (CV(%)). Specifically, the present invention relates to a cellulose fiber wherein Coefficient of Variation of section diameter (CV(%)) of a mono-filament constituting a multi-filament prepared by dissolving a cellulose powder in liquid N-methylmorpholine N-oxide (hereinafter referred to “NMMO”) is below 2.5. According to the present invention, a lyocell multi-filament is produced comprising the steps of (i) preparing a spinning solution by homogeneously dispersing, swelling and dissolving cellulose powder in a NMMO solution; (ii) spinning the spinning solution into an air gap through a spinning nozzle; and (iii) coagulating the extruded-spun spinning solution in a coagulation bath. In particular, the coagulating step is adjusted by means of a coagulation coefficient in the range of 0.8 to 1.3 and the coagulation coefficient is expressed as T D /T C , T D =T D +T A 90 and T D T A and T c mean the temperature of a spinning solution, the temperature of cooling air applied in an air gap and the temperature of a coagulation bath, respectively.

1 . A process for producing a lyocell multi-filament in which the process includes preparing a spinning solution by homogenously dispersing, swelling and dissolving cellulose powder in a NMMO solution;
 spinning the spinning solution into an air gap through a spinning nozzle; and   coagulating the extruded-spun spinning solution in a coagulation bath, characterized in that the coagulating is adjusted by means of a coagulation coefficient in the range of 0.8 to 1.3 and the coagulation coefficient is expressed as shown below,   coagulation coefficient=T D /T c , T D =T D +T A −90; and   T D , T A  and T c  mean the temperature of a spinning solution, the temperature of cooling air applied in an air gap and the temperature of a coagulation bath, respectively.   
     
     
         2 . The process of producing a lyocell multi-filament according to  claim 1 , wherein the coagulation coefficient is 1. 
     
     
         3 . The process of producing a lyocell multi-filament according to  claim 1 , wherein the temperature of the coagulation bath to 15 to 25° C. 
     
     
         4 . The process of producing a lyocell multi-filament according to  claim 1 , wherein the fineness of lyocell multi-filament is 800 to 3300 denier. 
     
     
         5 . The process of producing a lyocell multi-filament according to  claim 1 , wherein T D , T A , T D  and T c  are 100 to 110° C., 5 to 15° C., 15 to 35° C. and 15 to 35° C., respectively. 
     
     
         6 . A lyocell multi-filament for use of tire dip cord produced according to  claim 1  and with following physical properties:
 800 to 3300 denier in entire fineness; 
 0.5 to 2.0 denier in each monofilament fineness; 
 6.4 to 8.3 g/d in tenacity of the multi-filament, 
 5.7 to 7.1% in breaking elongation, and 
 less than 2.5% in Coefficient of Variation of section diameter (CV(%))