PURPOSE: To obtain the title pitch which can realize improvements in the strength and elastic modulus of carbon fiber by centrifuging a carbonaceous pitch to remove most part of ash contained therein and then filtering it through a filter.
CONSTITUTION: A carbonaceous pitch melted by heating to 280-400°C so as to provide a viscosity of 0.05-90Pa.s is centrifuged on a centrifugal separator at a centrifugal force of 10,000-40,000G to remove most part of ash contained therein, giving a carbonaceous pitch having an ash content of 100ppm or less. This pitch is filtered through a filter made of a sintered metal having a pore diameter of 0.05-5μm and a porosity of 50% or higher in an inert gas atmosphere under a filtering pressure of 1-100kgf/cm2 to remove the remaining ash, thus giving a superclean carbonaceous pitch having an Fe content of 2ppm or less, an Al content of 1ppm or less, an Si content of 3.3ppm or less, and a total content of Fe, Al, and Si of 5ppm or less.
MIURA MASARU
TOKI HIROSHI
