Method of preparing pitch for carbon fiber

Abstract

Disclosed herein is a method of preparing an isotropic pitch for carbon fiber having a high softening point, and more particularly, a method of preparing an isotropic pitch for carbon fiber by mixing petroleum residues with C9 fraction to form a mixture and then heating the mixture to perform heat polymerization. With the method of preparing an isotropic pitch according to the present invention, a separate catalyst is not required, and the isotropic pitch for carbon fiber having a low softening point may be prepared with a high yield even at a relatively low temperature.

What is claimed is: 
     
         1 . A method of preparing a pitch for carbon fiber, the method comprising:
 a mixing step of mixing petroleum residues with C9 fraction to form a mixture; and   a heating step of heating the mixture.   
     
     
         2 . The method of  claim 1 , wherein the heating step is performed by multi-step heating in two steps or more. 
     
     
         3 . The method of  claim 1 , wherein the heating step includes:
 a primary heating step of primarily heating the mixture;   a secondary heating step of raising a temperature after the primary heating; and   a tertiary heating step of raising a temperature after the secondary heating.   
     
     
         4 . The method of  claim 3 , wherein a heating temperature in the primary heating step is about 80° C. to about 100° C. 
     
     
         5 . The method of  claim 3 , wherein a heating time in the primary heating step is about 1 hour to about 2 hours. 
     
     
         6 . The method of  claim 3 , wherein in the primary heating step, a chain extension reaction is induced. 
     
     
         7 . The method of  claim 3 , wherein a heating temperature in the secondary heating step is about 250° C. to about 300° C. 
     
     
         8 . The method of  claim 3 , wherein a heating time in the secondary heating step is about ½ hour to about 2 hours. 
     
     
         9 . The method of  claim 3 , wherein in the secondary heating step, low boiling point materials are removed. 
     
     
         10 . The method of  claim 3 , wherein a heating temperature in the tertiary heating step is about 320° C. to about 360° C. 
     
     
         11 . The method of  claim 3 , wherein a heating time in the tertiary heating step is about 3 hours to about 8 hours. 
     
     
         12 . The method of  claim 3 , wherein in the tertiary heating step, a condensation reaction occurs. 
     
     
         13 . The method of  claim 1 , wherein the petroleum residues include naphtha cracking residues. 
     
     
         14 . The method of  claim 1 , wherein the petroleum residues include pyrolyzed fuel oil (PFO). 
     
     
         15 . The method of  claim 1 , wherein the petroleum residues comprise a substance from which low boiling point materials are removed. 
     
     
         16 . The method of  claim 1 , wherein the C9 fraction has aromaticity of about 40% to about 60%. 
     
     
         17 . The method of  claim 1 , wherein in the mixture, the C9 fraction is mixed at a content of about 10 parts to about 50 parts by weight, based on 100 parts by weight of the petroleum residues.