Mitsubishi Chemical Corporation

Takeshi Nii

Takayuki Kobayashi

Atsushi Nakajima

Kenichi Watanabe

Manabu Kaneko

Masahiro Ichino

Takuya Teranishi

Naoki Aoyama

Yoshiko Irie

Kiharu Numata

Yasuyuki Fujii

Masahiro Hata

Norifumi Hirota

Takayuki Kiriyama

Hiroyuki Nakao

Yuusuke Shinmen

Akiyoshi Kogame

Harumi Matsuda

Teppei Miura

Naomasa Matsuyama

Shouhei Mori

Yusuke Shinmen

Shigekazu Takeda

Toshiyuki Itou

A method of producing a carbon fiber bundle is provided, involving performing a flame-proof treatment to a carbon-fiber-precursor acryl fiber bundle having a single-fiber fineness of 1.5 dtex or more and 5.0 dtex or less, and having a roundness of 0.7 or more and 0.9 or less in a cross-section shape perpendicular to a fiber axis of the single fiber to obtain a flame-proofed fiber bundle; and performing a carbonization treatment to the flame-proofed fiber bundle.

Carbon-fiber-precursor fiber bundle, carbon fiber bundle, and uses thereof

A carbon fiber bundle, wherein an average single-fiber fineness is from 1.0 to 2.4 dtex and a roundness is from 0.7 to 0.9 in a shape of a cross-section perpendicular to a fiber axis of a single fiber; the roundness being determined with equation (1): roundness=4&#x3c0;S/L, where S is a cross-sectional area of the single fiber and L is a circumferential length of the single fiber, and S and L are obtained by observing, under an SEM, the cross-section of the single fiber perpendicular to the fiber axis of the single fiber and analyzing the obtained image.

Provided are: a polyacrylonitrile-based precursor fiber for the production of a carbon fiber having a large single-fiber fineness, said precursor fiber ensuring high heat stability of a spinning dope and excellent productivity; and a copolymer suitable for the production of said precursor fiber. Also provided are: high-quality carbon fiber bundles which have a large single-fiber fineness and excellent productivity; a process for producing the same; and a process for producing flameproofed fiber bundles suitable for the production of the carbon fiber bundles. A polyacrylonitrile-based copolymer which comprises 93.0 to 99.4 mol % of acrylonitrile units, 0.5 to 4.0 mol % of (meth)acrylamide-based units, and 0.1 to 3.0 mol % of unsaturated carboxylic acid hydroxyalkyl ester units and in which the (meth)acrylamide-based units are (meth)acrylamide units and/or (meth)acrylamide derivative units having a molecular weight of 105 or less; a precursor fiber comprising the copolymer; a process for producing flameproofed fiber bundles which uses precursor fiber bundles consisting of the precursor fiber; carbon fiber bundles; and a process for production thereof.

Polyacrylonitrile-based copolymer, polyacrylonitrile-based precursor fiber for carbon fiber, carbon fiber bundles, process for producing stabilized fiber bundles, and process for producing carbon fiber bundles

A carbon-fiber-precursor acryl fiber bundle, including a polyacrylonitrile-based copolymer that contains from 95 to 99 mol % of an acrylonitrile unit and from 1 to 5 mol % of a hydroxyalkyl (meth)acrylate unit, where the fiber bundle has a single-fiber fineness of from 1.5 dtex to 5.0 dtex and a roundness of from 0.75 to 0.9 in a cross-section shape perpendicular to a fiber axis of the single fiber; the roundness being determined with equation (1): roundness=4&#x3c0;S/L, where S is a cross-sectional area of the single fiber and L is a circumferential length of the single fiber, and S and L are obtained by observing, under an SEM, the cross-section of the single fiber perpendicular to the fiber axis of the single fiber and analyzing the obtained image.

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Tokyo, Japan

Takeshi Nii