High strength copolymerized aramid fibers

Abstract

A high-strength copolymerized aramid fiber according to the present invention includes aramid copolymers which contain an aromatic group substituted with a cyano group (—CN), so as to have a chord modulus of 700 to 1,100 g/d. The high strength copolymerized aramid fiber of the present invention has an orientation angle of 10 to 25° and an enhanced strength of 20 to 35 g/d. The aramid fiber of the present invention is fabricated by properly controlling a shear rate on an inner wall of a spinneret when a spinning dope passes through the spinneret, or elongating an aramid yarn that passes through a coagulation tube while coagulating the same, so as to have higher chord modulus and strength than the conventional aramid fibers. Therefore, the aramid fiber is useful as a material for various industries.

1 . A high-strength copolymerized aramid fiber, comprising aramid copolymers which contain an aromatic group substituted with a cyano group (—CN), so as to have a chord modulus of 700 to 1,100 g/d. 
     
     
         2 . The high-strength copolymerized aramid fiber according to  claim 1 , wherein the aramid fiber has a strength of 20 to 35 g/d. 
     
     
         3 . The high-strength copolymerized aramid fiber according to  claim 1 , wherein the aramid fiber has an orientation angle of 10 to 25°. 
     
     
         4 . The high-strength copolymerized aramid fiber according to  claim 1 , wherein the aramid fiber has a monofilament fineness of 0.5 to 5 deniers. 
     
     
         5 . The high-strength copolymerized aramid fiber according to  claim 1 , wherein the aramid copolymer film containing an aromatic group substituted with a cyano group (—CN) has a repeat unit represented by the following formula I:
   —(NH-A-NH CO—Ar—CO)—
 
 (wherein Ar is an aromatic group represented by Formula II below, and A is an aromatic group represented by Formula III below or an aromatic group having a ratio of the aromatic group of Formula II below to the aromatic group of Formula III below in a range of 1:9 to 9:1)