Polybenzimidazole carbon fiber and method for manufacturing same

Abstract

The present application provides polybenzimidazole carbon fiber that does not require infusibilization treatment and method for producing same.

1 . A polybenzimidazole carbon fiber comprising:
 a structure obtained by turning a precursor fiber including polybenzimidazole into a carbon fiber under application of heat,   wherein the polybenzimidazole includes a structure represented by General Formula (1) or General Formula (2) below as a structural unit, and   wherein the polybenzimidazole carbon fiber has an elastic modulus in tension of 100 GPa or more and a tensile strength of 0.8 GPa or more:   
       
         
           
           
               
               
           
         
         where in the General Formulas (1) and (2), R 1  and R 3  each represent a trivalent or tetravalent group of one selected from the group consisting of aryl groups and unsaturated heterocyclic groups that are expressed by any one of Structural Formulas (1) to (10) below, and R 2  represents a bivalent group of one selected from the group consisting of aryl groups and unsaturated heterocyclic groups that are expressed by any one of the Structural Formulas (1) to (10), alkenylene groups including from 2 to 4 carbon atoms, an oxygen atom, a sulfur atom, and a sulphonyl group: 
       
       
         
           
           
               
               
           
         
       
     
     
         2 . The polybenzimidazole carbon fiber according to  claim 1 , wherein the polybenzimidazole carbon fiber is a continuous fiber having a fiber diameter of 8 μm or more. 
     
     
         3 . A method for producing a polybenzimidazole carbon fiber, the method comprising:
 spinning, in an acid solution, a polymer including polybenzimidazole including a structure represented by General Formula (1) or General Formula (2) below as a structural unit, to thereby obtain a first precursor fiber of the polymer;   contacting the first precursor fiber with a basic solution, and neutralizing the acid solution remaining in the first precursor fiber to be removed, to thereby obtain a second precursor fiber; and   heating the second precursor fiber at a temperature of from 1,000° C. to 1,600° C. under an inert gas, to thereby turn the second precursor fiber into a carbon fiber:   
       
         
           
           
               
               
           
         
         where in the General Formulas (1) and (2), R 1  and R 3  each represent a trivalent or tetravalent group of one selected from the group consisting of aryl groups and unsaturated heterocyclic groups that are expressed by any one of Structural Formulas (1) to (10) below, and R 2  represents a bivalent group of one selected from the group consisting of aryl groups and unsaturated heterocyclic groups that are expressed by any one of the Structural Formulas (1) to (10), alkenylene groups including from 2 to 4 carbon atoms, an oxygen atom, a sulfur atom, and a sulphonyl group: 
       
       
         
           
           
               
               
           
         
       
     
     
         4 . The method for producing a polybenzimidazole carbon fiber according to  claim 3 , wherein the acid solution is polyphosphoric acid and the basic solution is an ethanol solution of triethylamine. 
     
     
         5 . The method for producing a polybenzimidazole carbon fiber according to  claim 4 , wherein the contacting is allowing the first precursor fiber to pass through a bath of the ethanol solution of triethylamine for from 5 seconds to 30 seconds to neutralize the polyphosphoric acid remaining in the first precursor fiber to be removed. 
     
     
         6 . The method for producing a polybenzimidazole carbon fiber according to  claim 3 ,
 wherein the spinning further comprises: coagulating, in a coagulation bath, a reaction solution of the polymer obtained through polymerization in a first acid solution, to thereby obtain a first coagulated matter of the polymer; contacting the first coagulated matter with a first basic solution to neutralize the first acid solution remaining in the first coagulated matter to be removed, to thereby obtain a second coagulated matter; and dissolves the second coagulated matter in a second acid solution to prepare a raw liquid for spinning, and spins the raw liquid for spinning, to thereby obtain a first precursor fiber of the polymer, and   wherein the contacting is contacting the first precursor fiber with a second basic solution, and neutralizing the second acid solution remaining in the first precursor fiber to be removed, to thereby obtain a second precursor fiber.   
     
     
         7 . The method for producing a polybenzimidazole carbon fiber according to  claim 6 , wherein the first acid solution is polyphosphoric acid, the first basic solution is an aqueous sodium hydrogen carbonate solution, the second acid solution is methanesulfonic acid, and the second basic solution is an ethanol solution of triethylamine. 
     
     
         8 . The method for producing a polybenzimidazole carbon fiber according to  claim 7 , wherein the contacting is allowing the first precursor fiber to pass through a bath of the ethanol solution of triethylamine for from 5 seconds to 30 seconds, and neutralizing the methanesulfonic acid remaining in the first precursor fiber to be removed. 
     
     
         9 . The method for producing a polybenzimidazole carbon fiber according to  claim 3 , wherein a heating temperature of the heating is a temperature of from 1,200° C. to 1,400° C.