Process for producing carbon fibers and carbon fibers made therefrom

Abstract

The present disclosure relates to a process for producing carbon fibers utilizing a salt of an organic cation containing a C═N imine group, and carbon fibers produced by such process.

What is claimed is: 
     
         1 . A process for producing carbon fibers, the process comprising:
 a. preparing a polymer solution comprising polyacrylonitrile (PAN) polymer;   b. spinning the polymer solution in step (a) by wet spinning or air-gap spinning to form carbon fiber precursor fibers, wherein said spinning comprises filtering and extruding the polymer solution into a coagulation bath;   c. drawing the carbon fiber precursor fibers through one or more draw and wash baths, resulting in drawn carbon fiber precursor fibers that are substantially free of solvent; and   d. oxidizing the drawn carbon fiber precursor fibers of step c) to form stabilized carbon fiber precursor fibers and then carbonizing the stabilized carbon fiber precursor fiber, thereby producing carbon fibers;   
       wherein at least one salt of an organic cation containing a C═N imine group is added to the polymer solution in step (a) and/or to the coagulation bath in step (b). 
     
     
         2 . The process according to  claim 1 , wherein preparing the polymer solution at step (a) comprises polymerizing acrylonitrile with one or more co-monomer(s) in a medium. 
     
     
         3 . The process according to  claim 1 , wherein the at least one salt of an organic cation containing a C═N imine group is added to the polymer solution in step (a). 
     
     
         4 . The process according to  claim 2 , wherein the one or more co-monomer(s) is selected from the group consisting of methacrylic acid (MAA), acrylic acid (AA), itaconic acid (ITA), vinyl-based esters, and other vinyl derivatives; and mixtures thereof. 
     
     
         5 . The process according to  claim 2 , wherein the one or more co-monomer(s) is selected from the group consisting of itaconic acid, methacrylic acid, acrylic acid, vinyl-based esters, and other vinyl derivatives, and mixtures thereof. 
     
     
         6 . The process according to  claim 1 , wherein the at least one salt of an organic cation containing a C═N imine group is added to the coagulation bath in step (b). 
     
     
         7 . The process according to  claim 6 , wherein the at least one salt of an organic cation containing a C═N imine group is present in the coagulation bath in an amount of less than or equal to 15% by weight relative to the weight of the coagulation bath. 
     
     
         8 . The process according to  claim 6 , wherein the carbon fiber precursor fibers formed are in the coagulation bath for less than or equal to 15 minutes. 
     
     
         9 . The process according to  claim 1 , wherein the salt of an organic cation containing a C═N imine group is present in one or more of the draw and wash baths in step c). 
     
     
         10 . The process according to  claim 9 , wherein the salt of an organic cation containing a C═N imine group is present in one or more of the draw and wash baths in an amount of less than or equal to 15%; by weight relative to the weight of the one or more draw and wash baths. 
     
     
         11 . The process according to  claim 1 , wherein the salt of an organic cation containing a C═N imine group is added in an amount effective for the organic cation containing a C═N imine group to be substantially uniformly distributed throughout the carbon fiber precursor fibers formed in step (c). 
     
     
         12 . The process according to  claim 1 , wherein the salt of an organic cation containing a C═N imine group is a salt of guanidinium ion, amidinium ion, or pyrimidinium ion. 
     
     
         13 . The process according to  claim 1 , wherein the carbon fibers produced have a core ratio of from 10% to 50%. 
     
     
         14 . The process according to  claim 1 , wherein the carbon fibers produced have a tensile strength of from 450 to 1000 ksi. 
     
     
         15 . The process according to  claim 1 , wherein the carbon fibers produced have a tensile modulus of from 30 to 48 msi.