| 摘要 |
PROBLEM TO BE SOLVED: To provide a carbon fiber bundle exhibiting stable physical properties with a precursor having an ultrasmall difference in crystal structure between the fiber bundles even in the case of≥20,000 filaments. SOLUTION: A fiber bundle of an acrylonitrile-based carbon fiber precursor having≥20,000 number of filaments is used. The fiber bundle has≤0.65°average of the half-value width for (100) reflection of polyacrylonitrile detected at a position where 2θis 17°in the XRD (X ray diffraction) measurement carried out for each of fiber bundles obtained by cutting the fiber bundle into 5 cm fiber length and then dividing the fiber bundle into about 2,000 number of filaments, respectively. Furthermore, the fiber bundle has≤2.5 CV (coefficient of variation) value indicating the degree of dispersion of crystal size calculated from the half-value width. The fiber bundle of the acrylonitrile-based carbon fiber precursor can be produced by extruding a spinning solution containing an acrylonitrile-based polymer into a spinning bath at a concentration of a solvent without exceeding 60 mass% to provide a coagulated tow. The resultant coagulated tow is then drawn in boiling water to a ratio without exceeding 4.0 times. COPYRIGHT: (C)2008,JPO&INPIT
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