Para-aramid fiber and method of preparing the same

Abstract

An aramid fiber and a method of producing the same is disclosed, which is capable of realizing high surface uniformity and improved tensile strength and elongation property, wherein the method comprises preparing an aromatic polyamide by polymerizing aromatic diamine with aromatic diacid halide; preparing a spinning dope by dissolving the aromatic polyamide in a solvent; and extruding the spinning dope through a spinneret, and sequentially passing the spinning dope through an air gap, a coagulation bath filled with a coagulation solution, and a coagulation tube having a jet opening, connected with the bottom of the coagulation bath, to obtain a filament wherein a distance from the upper surface of the coagulation solution contained in the coagulation bath to the jet opening of the coagulation tube is within a range between 10 and 35 mm.

1 . A method of preparing a para-aramid fiber comprising:
 preparing an aromatic polyamide by polymerizing aromatic diamine with aromatic diacid halide;   preparing a spinning dope by dissolving the aromatic polyamide in a solvent; and   extruding the spinning dope through a spinneret, and sequentially passing the spinning dope through an air gap, a coagulation bath filled with a coagulation solution, and a coagulation tube having a jet opening, connected with the bottom of the coagulation bath, to obtain a filament,   wherein a distance from the upper surface of the coagulation solution contained in the coagulation bath to the jet opening of the coagulation tube is within a range between 10 and 35 mm.   
     
     
         2 . The method of  claim 1 , wherein a distance from the bottom of the coagulation bath to the jet opening is within a range between 5 and 20 mm. 
     
     
         3 . The method of  claim 1 , wherein a distance from the upper surface of the coagulation solution contained in the coagulation bath to the bottom of the coagulation bath is within a range between 5 to 15 mm. 
     
     
         4 . The method of  claim 1 , wherein the plurality of jet opening are arranged at different heights so that a coagulation solution from different positions is jetted to the inside of the coagulation tube therethrough. 
     
     
         5 . The method of  claim 1 , wherein a ratio of a jetting speed of the coagulation solution jetted out from the jet opening to a discharging speed of the filament discharged from the coagulation tube is within a range of 0.8:1 to 1.2:1. 
     
     
         6 . The method of  claim 5 , wherein the jetting speed of the coagulation solution jetted out from the jet opening is within a range between 150 to 800 mpm. 
     
     
         7 . The method of  claim 1 , wherein the coagulation solution contained in the coagulation bath is a sulfuric acid solution, and a concentration of the sulfuric acid solution is within a range between 5 to 15 weight %. 
     
     
         8 . The method of  claim 1 , wherein the coagulation solution contained in the coagulation bath is a sulfuric acid solution, and the sulfuric acid solution is maintained at a temperature between 1 to 10° C. 
     
     
         9 . A para-aramid fiber formed in such a structure that an amide group is connected with aromatic rings, and the aromatic rings are linearly connected through the amide group, wherein a surface roughness is RMS 0.2 μm or less, and a tensile strength is within a range between 22 g/d and 26 g/d. 
     
     
         10 . The para-aramid fiber of  claim 9 , wherein the aramid fiber has an elongation of 2.8 to 3.5%. 
     
     
         11 . The para-aramid fiber of  claim 9 , wherein the aramid fiber has a 5N or less of maximum resistance on drawing from a fabric, wherein the fabric is a plain-woven fabric having a weaving density of 260 g/m 2 , and the plain-woven fabric is made of the aramid fiber having 1500 denier as weft and warp.