Toray Industries, Inc.

Ayanobu Horinouchi

Tomoyuki Horiguchi

Kentaro Kajiwara

Satoru Shimoyama

Fumitaka Watanabe

Yuuki Okishima

A method of producing a carbon fiber bundle suppresses penetration of a process oil agent into the fiber surface layer and suppresses adhesion between fibers and the generation of surface voids, and also provides a carbon fiber bundle. The carbon fiber bundle is characterized by having a crystallite size of 3.0 nm or less as measured by wide-angle X-ray diffraction, containing a point where the Si/C ratio is 10 or more as calculated by SIMS (secondary ion mass spectrometry) in the region ranging from 0 to 10 nm in depth from the fiber surface, and also showing a Si/C ratio of 1.0 or less as calculated by SIMS at a depth of 10 nm from the fiber surface.

Carbon fiber bundle and production method thereof

A method of producing a precursor fiber for carbon fiber includes extruding a polyacrylonitrile copolymer solution from a spinneret into the air, immersing it in a coagulation bath liquid stored in a coagulation bath, redirecting traveling of the coagulating fiber bundle by a first guide immersed in the coagulation bath disposed below the spinneret, and pulling it out of the coagulation bath liquid into the air to prepare a coagulated fiber bundle, which is then subjected to at least a washing step in water, stretching step, oil agent applying step, and drying step, wherein the depth-directional coagulation bath immersion length, which means a distance between the starting point of the immersion of the spinning dope solution in the coagulation bath liquid and the first guide immersed in the coagulation bath where traveling of the coagulating fiber bundle is redirected, is 3 to 40 cm.

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Otsu, Japan

Ayanobu Horinouchi