| 摘要 |
PROBLEM TO BE SOLVED: To provide a method for producing a carbon fiber, in which impurities such as a tar-like substance to be stuck to the surface of a carbon fiber bundle are removed efficiently so that the carbon fiber bundle can be restrained from being wound around a heating roll.SOLUTION: The method for producing the carbon fiber comprises the steps of: performing flameproofing treatment on a polyacrylonitrile-based carbon fiber precursor fiber bundle, which has the single fiber fineness equal to or higher than 1.0 dtex and the total fineness equal to or higher than 30,000 dtex, in an oxidizing atmosphere; performing carbonization treatment on the flameproofing treatment-performed carbon fiber precursor fiber bundle in an inert atmosphere; performing electrolytic oxidation treatment on the carbonization treatment-performed carbon fiber precursor fiber bundle; immersing the electrolytic oxidation treatment-performed carbon fiber precursor fiber bundle in warm water of 60°C or higher or boiling water to perform warm water treatment thereon; performing ultrasonic treatment on the warm water treatment-performed fiber bundle in the water of 1-40°C; and performing heating roll treatment on the ultrasonic treatment-performed fiber bundle at 140°C or higher for 3 seconds or longer. The foreign matter or the like, which is stuck to the surface of the carbon fiber bundle, can be removed efficiently by the flameproofing treatment, the carbonization treatment and the electrolytic oxidation treatment so that the carbon fiber bundle can be restrained from being wound around the heating roll when the carbon fiber bundle is dried.SELECTED DRAWING: None |
