PURPOSE: To obtain a carbon fiber having high performance in high efficiency, by heat-treating a frame-resistant fiber of an acrylonitrile polymer having a fiber density falling within a specific range and carbonizing the heat treated fiber.
CONSTITUTION: An acrylonitrile polymer fiber having a fiber density of 1.34W1.40g/ml is heat-treated in an inert gas atmosphere at a heat-treatment initiation temperature of 300±50°C, a rate of temperature rise of 50W250°C/min and a heat-treatment completion temperature of 450±50°C. The treated fiber is further heat-treated in an inert gas atmosphere at 500W700°C and a rate of temperature rise of ≤50° preferably or ≤1min and carbonized at ≥1,000°C, preferably 1,000W1,900°C to obtain the objective carbon fiber.
IMAI YOSHITAKA
NAKATANI SOJI
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