| 摘要 |
PURPOSE:To obtain an acrylonitrile-based carbon fiber having high tenacity and elastic modulus, by reducing the unevenness in the flame-resistant treatment of a stock fiber and, at the same time, using a precarbonization step under a specific condition. CONSTITUTION:An acrylonitrile fiber bundle having a single fiber fineness of 0.3-1.5 d and a fiber bundle fineness of 1,000-20,000 d is passed through plural furnaces having oxidizing atmosphere and maintained at different treatment and then passed through a flame-resistance treatment furnace. The flame- resistant treatment is carried out under a condition satisfying the formula [rhoo, pik and pin are density (g/ml) of stock fiber, fiber finished with frame-resistant treatment and fiber passed through n-th frame-resistant treatment furnace, respectively; k is total number of furnaces] until the fiber density reaches 1.34-1.40g/ml. The treated fiber is subjected to precarbonization treatment in an inert gas atmosphere at 300-500 deg.C and a rate of temperature increase of 10-250 deg.C/min. The precarbonized fiber is carbonized at 1,300-1,800 deg.C optionally after heat-treatment at <=800 deg.C.
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