| 摘要 |
PURPOSE:To obtain carbon fibers having a high strength and elastic modulus, by feeding an acrylonitrile based fiber bundle having a specific fineness to plural flameproofing treatment furnaces at a different treating temperatures in an oxidizing atmosphere, passing the fiber bundle therethrough under specific conditions and heating and heat-treating the fiber bundle stepwise in an inert gas atmosphere. CONSTITUTION:An acrylonitrile polymer fiber bundle having 0.3-1.5de fiber fineness and 1,000-20,000de total fiber fineness is fed to plural flameproofing furnaces at 200-350 deg.C different treating temperatures in an oxidizing atmosphere and flameproofed while stretching at a ratio to give 3-30% elongation up to 1.22g/ml fiber density and <=50% total elongation up to 1.26g/ml fiber density under conditions to give the density of fibers after passing through the flameproofing furnaces satisfying the formula [rho0 is fiber density (g/ml); rhok is density (g/ml) of filaments after completing the flameproofing treatment; rhon is fiber density (g/ml) after passing through the flameproofing furnace in the n-th stage; 5n is treating time (min) in the furnace in the n-th stage; k is the total number of stages] so that the density after the treatment may be 1.34-1.40g/ml. The flameproofed filaments are then treated at 300-800 deg.C in an inert gas atmosphere to give >=75% orientation parameter pi002 and the treated filaments are further heat-treated at 1,300-1,800 deg.C.
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