| 摘要 |
PURPOSE:To obtain a carbon fiber having high strength and elastic modulus, by heat-treating a carbonaceous raw material, treating the obtained mesophase pitch with a centrifugal separator furnished with a light medium-heavy medium separation weir, melt-spinning collected heavier component and subjecting the spun fiber to infusibilization, carbonization, etc. CONSTITUTION:A carbonaceous raw material (e.g. coal-based pitch) is heat- treated and the treated material is supplied through a feed pipe 6 to a centrifugal separator preferably in a state of <=430 deg.C and a viscosity of 0.1-10ps. The material is separated in layers at the inner wall of a rotary cylinder 1 into a heavy medium layer having high anisotropy and a light medium layer in which development of anisotropy is not sufficient. The heavy medium is passed through a gap between a heavy medium over flow weir 3 and a light medium-heavy medium separation weir 5 and taken out through a heavy medium discharging port 8. The heavy component composed of a mesophase pitch having a softening point of preferably 220-320 deg.C (e.g. having a softening point of 305 deg.C and anisotropic ratio of 93% at a spinning temperature) is spun under molten state and the fiber is successively subjected to infusibilization, carbonization and, if necessary, graphitization to obtain the objective fiber.
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