Highly elastic copolymerized aramid fibers

Abstract

A highly elastic copolymerized aramid fiber of the present invention includes aramid copolymers which contain an aromatic group substituted with a cyano group (—CN), so as to have an elastic modulus of 1,100 to 1,300 g/d, a strength of 17 to 30 g/d and an elongation of 1 to 4%. According to the present invention, the content of the solvent remaining in the fiber is small in a range of less than 100 ppm, and the crystallinity, crystal size and orientation angle of the fiber are properly controlled by the heat treatment. Therefore, the elastic modulus is greatly improved even without a decrease in the strength, as compared to the conventional aramid fibers. The present invention is useful as a material for various products requiring high elasticity as well as high strength of aramid fibers such as bulletproof materials.

1 . A highly elastic copolymerized aramid fiber, comprising aramid copolymers which contain an aromatic group substituted with a cyano group (—CN), so as to have an elastic modulus of 1,100 to 1,300 g/d, a strength of 17 to 30 g/d and an elongation of 1 to 4%. 
     
     
         2 . The highly elastic copolymerized aramid fiber according to  claim 1 , wherein the highly elastic copolymerized aramid fiber has a crystallinity of 60 to 80%, a crystal size of 100 to 200 Å (200 faces) and 100 to 170 Å (110 faces) and an orientation angle (200 faces) of 2 to 9°. 
     
     
         3 . The highly elastic copolymerized aramid fiber according to  claim 1 , wherein the aramid copolymers which contain an aromatic group substituted with a cyano group (—CN) has a repeat unit represented by the following formula
   —(NH-A-NH CO—Ar—CO)—  [Formula I]
 
 (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)