A process for producing polymer fiber and polymer fiber made therefrom

Abstract

The present disclosure relates generally to a process for producing polymer fibers, typically polyacrylonitrile-based fibers, the properties of which are controlled by certain parameters of the process, such as the amount of jet stretch, the amount of wet stretch, and the amount of hot stretch employed. The present disclosure also relates to a process for producing carbon fiber from such polymer fibers.

1 . A process for producing polymer fiber, the process comprising:
 a) spinning a polymer solution into a coagulation bath, wherein a jet stretch is applied, to form coagulated fiber;   b) subjecting the coagulated fiber obtained in step (a) to a wet stretch to form a first drawn fiber; and   c) subjecting the first drawn fiber obtained in step (b) to a hot stretch, thereby forming the polymer fiber;
 wherein the amount of jet stretch, the amount of wet stretch, and the amount of hot stretch are effective to achieve the following properties wherein: 
 the Herman's orientation factor of the polymer fiber produced is at least 0.60, and 
 the crystallite thickness of the polymer fiber produced is at least 3 nm, greater than the crystallite thickness of the first drawn fiber. 
   
     
     
         2 . The process according to  claim 1 , wherein the crystallinity of the coagulated fiber is no more than 8%, greater than the crystallinity of the first drawn fiber. 
     
     
         3 . The process according to  claim 1 , wherein a linear mass density of the polymer fiber produced is from 0.7 to 1.2, denier per filament. 
     
     
         4 . The process according to  claim 1 , wherein an average diameter of the coagulated fiber is at least 40 μm. 
     
     
         5 . The process according to  claim 1 , wherein an average diameter of the first drawn fiber is at least 15 μm. 
     
     
         6 . The process according  claim 1 , wherein the Herman's orientation factor of the coagulated fiber is at least 0.35. 
     
     
         7 . The process according to  claim 1 , wherein the Herman's orientation factor of the polymer fiber produced is at least 0.08 greater than the Herman's orientation factor of the first drawn fiber. 
     
     
         8 . The process according to  claim 1 , wherein an activation energy of structural relaxation for β c  of the polymer fiber produced is less than 700 kJ/mol. 
     
     
         9 . The process according to  claim 8 , wherein the activation energy of structural relaxation for β c  of the polymer fiber produced is from 500 to 600 kJ/mol. 
     
     
         10 . The process according to  claim 1 , wherein a cyclization activation energy of the polymer fiber produced is at least 7 kJ/mol greater than the cyclization activation energy of the first drawn fiber. 
     
     
         11 . The process according to  claim 1 , wherein a tenacity of the polymer fiber produced is at least 4 g/d. 
     
     
         12 . The process according to  claim 1 , wherein a Young's Modulus of the polymer fiber produced is at least 95 g/d. 
     
     
         13 . The process according to  claim 12 , wherein the Young's Modulus of the polymer fiber produced is 95 to 130 g/d. 
     
     
         14 . The process according to  claim 1 , wherein a peak temperature of a cyclization exotherm of the polymer fiber produced is at least 3° C. higher than the peak temperature of the cyclization exotherm of the coagulated fiber and/or the first drawn fiber. 
     
     
         15 . The process according to  claim 1 , wherein the polymer fiber produced is polyacrylonitrile-based polymer fiber. 
     
     
         16 . The process according to  claim 1 , wherein the spinning of the polymer solution is achieved by wet spinning. 
     
     
         17 . The process according to  claim 1 , wherein the coagulation bath comprises a mixture of DMSO and water. 
     
     
         18 . The process according to  claim 1 , wherein the polymer fiber produced is carbon fiber precursor fiber. 
     
     
         19 . A polymer fiber produced according to the process of  claim 1 . 
     
     
         20 . A process for producing carbon fiber, the process comprising oxidizing the polymer fiber according to  claim 19  to form stabilized carbon fiber precursor fibers and then carbonizing the stabilized carbon fiber precursor fiber, thereby producing carbon fiber.