PRODUCTION OF PRECURSOR PITCH FOR CARBON FIBER

PURPOSE:To obtain isotropic precursor pitch which is low in viscosity and excellent in spinnability, by extracting tar or tar pitch with a solvent to remove quinoline-insoluble matter and pyridine-insoluble matter and heat treating the pitch at a relatively high temp. for a short period of time through rapid heating. CONSTITUTION:Precursor pitch contg. 50-60wt% benzene-insoluble matter and a trace amt. of quinoline-insoluble matter, having a softening point of 200-240 deg.C and being substantially free from mesophase is produced. In order to produce pitch having such properties, tar or tar pitch is extracted with a solvent to remove quinoline-insoluble matter and pyridine to such an extent that the content of the quinoline-insoluble matter is trace while the content of the pyridine-insoluble matter is 5wt% or less. The temp. of the pitch is then raised at a temp. elevation rate of 7 deg.C/min or more under a reduced pressure of 20mmHg or less while an inert gas is flowed and the pitch is heat-treated at a max. treating temp. of 350-480 deg.C.