Carbon fiber bundle and method for producing same

Abstract

A carbon fiber bundle having high total fineness and extremely fine single fiber fineness is provided. The carbon fiber bundle includes continuous single fibers and satisfying the following (1) to (4): (1) a fineness of the single fiber is 0.0035-0.056 dtex; (2) a number of the single fibers in one carbon fiber bundle is 300-2500 thousand; (3) a strand strength of the carbon fiber bundle is 3000-10000 MPa; and (4) a strand elastic modulus of the carbon fiber bundle is 200-400 GPa.

What is claimed is: 
     
         1 . A carbon fiber bundle comprising a plurality of continuous single fibers and satisfying the following (1) to (4):
 (1) a fineness of the single fiber is 0.0035-0.056 dtex;   (2) a number of the single fibers in one carbon fiber bundle is 300-2500 thousand;   (3) a strand strength of the carbon fiber bundle is 3000-10000 MPa; and   (4) a strand elastic modulus of the carbon fiber bundle is 200-400 GPa.   
     
     
         2 . The carbon fiber bundle according to  claim 1 , wherein the single fibers are independent single fibers. 
     
     
         3 . The carbon fiber bundle according to  claim 1 , wherein the fineness of the single fiber is greater than 0.0054 dtex. 
     
     
         4 . A polyacrylonitrile-based carbon fiber bundle comprising a plurality of continuous single fibers, a crystal orientation π (%) and a graphite crystal size Lc (nm) of which obtained by a wide-angle X-ray diffraction method satisfy the following formula (1):
   77≦π−3.8× Lc≦ 80     formula (1)
 
 
     
     
         5 . A polyacrylonitrile-based carbon fiber bundle comprising a plurality of continuous single fibers, a graphite crystal size Lc (nm) of which obtained by a wide-angle X-ray diffraction method and a strand elastic modulus E (GPa) satisfy the following formula (2):
   3.28≦−1.05×10 −5   ×E   2 +0.0194× E−Lc ≦3.94  formula (2)
   
     
     
         6 . A production method of a carbon fiber bundle, comprising:
 preparing a dope by dissolving an acrylonitrile-based polymer in a solvent, wherein the acrylonitrile-based polymer is obtained by copolymerizing 96 mass % or more of acrylonitrile and a monomer, which is selected from a (meth)acrylic acid derivative, an itaconic acid derivative, and a (meth)acrylamide derivative, as a copolymer component;   discharging the dope from a spinneret into a coagulation liquid to coagulate the discharged dope to obtain a coagulated thread, wherein the spinneret comprises a perforate portion with a plurality of discharge holes that are arranged and an imperforate portion without discharge hole, and a discharge hole density of the perforate portion with the discharge holes is 600-1200/mm 2  and a number of the discharge holes is 300-2500 thousand;   after stretching the coagulated thread 1.0-1.5 times, performing stretch and wash to stretch the coagulated thread to a range of 1.5-6 times in a washing and stretching process comprising 2-10 baths having a temperature in a range of 50-100° C.; applying an oil agent comprising a silicone-based compound as a main component; drying the coagulated thread by passing the coagulated thread through a plurality of heating rollers; and heating the coagulated thread at a temperature of 130-200 ° C. to stretch the coagulated thread 1.3-7.0 times to obtain a polyacrylonitrile-based carbon fiber precursor fiber bundle having a total stretching ratio of 2-16 times;   heating in an oxidizing atmosphere to perform a stabilization process on the polyacrylonitrile-based carbon fiber precursor fiber bundle; and   heating in an inert atmosphere to carbonize the polyacrylonitrile-based carbon fiber precursor fiber bundle.