METHOD FOR PRODUCING ULTRA FINE CARBON FIBER AND ULTRA FINE CARBON FIBER, AND CARBON-BASED AUXILIARY CONDUCTIVE AGENT CONTAINING THE ULTRA FINE CARBON FIBER

PROBLEM TO BE SOLVED: To provide an ultra fine carbon fiber which is simpler and has better characteristics compared to a conventional ultra fine carbon fiber, and to provide a method for producing an ultra fine carbon fiber.SOLUTION: A method for producing an ultra fine carbon fiber includes: (1) a step of molding a composition formed of 100 pts.mass of a thermoplastic resin and 1 to 150 pts.mass of mesophase pitch in a molten state, and thereby fiberizing the mesophase pitch to obtain a resin composite fiber; (2) a stabilization step of making an oxidative substance in a gas phase state flow on the surface of the resin composite fiber, bringing the resin composite fiber into contact with the oxidative substance, stabilizing the fiber and the substance, and obtaining a resin composite stabilized fiber; and (4) a carbonization and calcination step of heating a stabilized fiber in the resin composite stabilized fiber under inert atmosphere, carbonizing or graphitizing the stabilized fiber, and obtaining an ultra fine carbon fiber.SELECTED DRAWING: None 【課題】従来と比較してより簡便に良好な特性の極細炭素繊維及び極細炭素繊維の製造方法を提供することである。【解決手段】（１）熱可塑性樹脂１００質量部とメソフェーズピッチ１〜１５０質量部とからなる組成物を溶融状態で成形することにより前記メソフェーズピッチを繊維化して樹脂複合繊維を得る工程と、（２）前記樹脂複合繊維の表面に気相状態の酸化性物質を流通させ、前記樹脂複合繊維と前記酸化性物質とを接触させて安定化し、樹脂複合安定化繊維を得る安定化工程と、（４）前記樹脂複合安定化繊維中の安定化繊維を不活性雰囲気下で加熱して炭素化乃至黒鉛化し、極細炭素繊維を得る炭化焼成工程と、を含む方法により極細炭素繊維を製造する。【選択図】なし