Method for producing cellulose fiber

Abstract

There is provided with a cellulose fiber suitable for industrial material which is produced by a process comprising following steps: producing NMMO solution made in a manner to dissolve 0.1 wt % to 10 wt % of salt and polyvinyl alcohol in concentrated N-Methyl Morpholine N-oxide (NMMO) in liquid state; producing cellulose solution in a manner that said NMMO solution is mixed with cellulose powder and then said cellulose powder is swelled to produce cellulose solution; obtaining multifilament by solidifying said cellulose solution reached at a coagulation bath through air layer after extruded-sprayed with spraying nozzle having orifices of 500 to 2000; and winding said multifilament for storing after in turn washing, drying and treating with organic solvent, and the cellulose fiber according to the present invention is suitable for industrial materials due to excellent mechanical strength. In addition, it is possible to obtain cellulose fiber by adding salts to concentrated NMMO in liquid state, in which micro-fibril is well oriented in direction of the fiber-axis making cellulose multifilament have excellent mechanical strength and excellent stability of morphology with lower shrinkage at high temperature. Furthermore, the cellulose fiber according to the present invention has a good fibrillation-resistance and excellent adhesion to rubber by using polyvinyl alcohol when used for tire-cord.

1 . Cellulose fibers produced by a method comprising the steps of: 
 (A) preparing a NMMO solution by dissolving 0.1 wt % to 10 wt % of salt and polyvinyl alcohol into a concentrated NMMO in liquid state;    (B) preparing a cellulose solution by mixing a cellulose powder with said NMMO solution, swelling and dissolving the said cellulose powder;    (C) obtaining a multi-filament by spinning said cellulose solution through a spinning nozzle with 500 to 2000 of orifices, making said cellulose reach a coagulation bath through a air layer and then solidifying said cellulose solution; and    (D) winding said multi-filament after water-washing, drying and finishing oil; wherein said multi-filament has physical properties as following:    (1) 700 to 3000 in total denier of the multi-filament, (2) 5 to 11 g/d in dried tenacity, (3) 4 to 12% in elongation, (4) 0.5 to 4.0% in elongation at specific load, (5) 200 to 400 g/d in modulus and (6) −0.5 to 3% in shrinkage.    
     
     
         2 . The cellulose fibers according to  claim 1 , characterized in that in step (A) the proportion of said salt and polyvinyl alcohol is 90:10 to 10:90 by weight.  
     
     
         3 . The cellulose fibers according to  claim 1 , characterized in that in step (A) said salt is a bivalent anion such as calcium chloride, ammonium chloride, calcium carbonate, calcium sulfate, sulfate magnesium and sulfate zinc.  
     
     
         4 . The cellulose fibers according to  claim 1 , characterized in that in step (B) an extruder is used for mixing said cellulose powder with said NMMO solution, swelling and dissolving said cellulose powder wherein said extruder is a twin-screw extrudes having 8 to 14 of barrels or screw being 24 to 64 in ratio of Length/Diameter (L/D).  
     
     
         5 . The cellulose fibers according to  claim 1 , characterized in that the fibrillation index of said cellulose fibers is below 5.  
     
     
         6 . The cellulose fibers according to  claim 1 , characterized in that in step (A) the degree of polymerization of said polyvinyl alcohol is 500 to 6000.  
     
     
         7 . The cellulose fibers according to  claim 1 , characterized in that in step (B) said cellulose powder is mixed with polyethylene, polyethylene glycol, polymethylmethacrylate and the additives a agent for dropping viscosity or TiO 2 , SiO 2 , carbon, carbon nano-tube, inorganic nano clay.  
     
     
         8 . A tire-cord comprising said cellulose fibers according to  claim 1.