Nippon Steel Corporation

Nippon Steel Chemical Co., Ltd.

Nippon Chemical Co., Ltd.

Nippon Steel Cporporation

Yasunori Sajiki

Takeshi Hamada

Tadao Tomioka

Tokuhiko Nishida

Masatoshi Furuyama

Mitsuaki Matsumoto

A process for producing a carbon fiber by subjecting a pitch fiber, obtained by melt spinning a carbonaceous mesophase pitch, to stabilization, followed by a carbonization or graphitization treatment, wherein the stabilization is carried out under an oxidative atmosphere containing 0.1% to 40% by volume of NO.sub.2 and 4% to 40% by volume of H.sub.2 O at a temperature of from 100.degree. C. to 400.degree. C.

Process for producing mesophase pitch-based carbon fibers

This invention relates to a coaltar pitch based carbon fiber having a high Young's modulus produced by using coaltar pitch as a starting material, which has a microstructure with a preferred orientation parameter (HWHM) of 10.degree. or less, a crystallite size (Lc(002)) of not more than 25 nm and not less than 18 nm and an interlayer spacing (d002) of not more than 0.345 nm and not less than 0.338 nm as determined by X-ray diffraction, and has a magnetoresistance of less than -0.40% and not less than -2.00% as measured by applying a magnetic field of 10 KG perpendicular to the fiber axis at liquid nitrogen temperature, and a Young's modulus of 55 ton.multidot.mm.sup.-2 or more, preferably 75 ton.multidot.mm.sup.-2 or more. The carbon fiber of this invention has a high Young's modulus, is flexible, and does not split in the fiber axis direction, and therefore it is easy to handle, is good in workability, and contributed also to improvement of the production efficiency. Further, when the carbon fiber of this invention is used in composite material, the resulting composite material can be expected to have an improved impact strength and hence can be used for various purposes.

Coaltar pitch based carbon fiber having high Young's modulus

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Kawasaki, Japan

Yasunori Sajiki