CONTINUOUS PRODUCTION OF CARBON FIBER

PROBLEM TO BE SOLVED: To obtain carbon fiber capable of oxidizing and carbonizing fiber yarn in just proportion within a short time and largely improving operability and useful for composite materials by interlacing and joining carbonizable fiber yarns, applying an oxidation reaction promoter to the joined part and carbonizing the fiber yarn under specific conditions. SOLUTION: The ends of carbonizable fiber yarn such as acrylic, cellulosic, polyvinyl alcohol-based or pitch-based fiber yarn are superposed in a length of 10-60 cm, preferably 30-40 cm and the fiber yarns are mutually interlaced and joined and then, oxidation reaction promoter of sulfite is applied to the joined part and further, the fiber yarn is subjected to oxidation treatment in an oxidation reaction furnace and carbonized to provide the objective carbon fiber. Furthermore, interlacing of the fiber yarn is preferably carried out by pressurized gas and the oxidation reaction promoter is preferably applied in a range of 15-20 wt.% to the fiber yarn.