Method for manufacturing pitch-based carbon fiber

Abstract

The present invention provides a method for manufacturing pitch-based carbon fiber by melt-spinning a mesophase pitch having optical anisotropy by using nozzles each equipped with an introduction hole entry portion, an introduction hole, an approach portion, and a discharge hole, and then applying thereto infusibilization, carbonization, or graphitization, wherein the mesophase pitch is passed through a plurality of contraction holes disposed in a substantially straight line in the introduction hole entry portion of each nozzle, then expanded in the introduction hole, and thereafter contracted in the approach portion and then spun by being passed through the discharge hole.

1 . A method for manufacturing pitch-based carbon fiber by melt-spinning a mesophase pitch having optical anisotropy by using nozzles each equipped with an introduction hole entry portion, an introduction hole, an approach portion, and a discharge hole, and applying thereto infusibilization, carbonization, or graphitization, characterized in that the flow of the mesophase pitch is passed through a plurality of contraction holes disposed in a substantially straight line in the introduction hole entry portion of each nozzle, then expanded in the introduction hole, and thereafter contracted in the approach portion and then spun by being passed through the discharge hole.  
     
     
         2 . A method for manufacturing pitch-based carbon fiber according to  claim 1 , characterized in that three or more contraction holes of 0.05 to 1 mm in diameter are disposed in a substantially straight line in said introduction hole entry portion.  
     
     
         3 . A method for manufacturing pitch-based carbon fiber according to  claim 1  or  2 , characterized in that the shape of the approach portion extending from the introduction hole to the discharge hole is a conical shape having an angle of inclination of 60 to 150 degrees.  
     
     
         4 . A method for manufacturing pitch-based carbon fiber according to  claim 1  or  2 , characterized in that a flat portion is formed on the terminal end of said approach portion and a discharge hole having a circular cross-sectional shape is disposed in the flat portion.