MANUFACTURE OF PITCH-BASED CARBON FIBER

PURPOSE:To obtain the titled high-quality carbon fiber free from cracks, by forming a pitch fiber having random structure at the cross-section perpendicular to the fiber axis by the melt-spinning of a precursor pitch under a temperature condition to get optically isotropic continuous phase of the precursor pitch, and making the pitch fiber infusible and carbonizing the fiber keeping the random structure. CONSTITUTION:A carbonaceous precursor pitch is spun to a pitch fiber by melt spinning, made infusible, carbonized, and if necessary, further graphitized to obtain a carbon fiber. In the above process, the melt-spinning is carried out at a temperature to get the optically isotropic continuous phase of the precursor pitch, and the obtained pitch fiber having random or onion structure at the cross-section perpendicular to the fiber axis is made infusible and carbonized under specific conditions to keep the random or onion structure also at the cross-section of the infusible fiber or carbonized fiber perpendicular to the fiber axis.