| 摘要 |
PROBLEM TO BE SOLVED: To provide a method for producing a flame-proofed fiber for a carbon fiber having high orientation, high strength and high appearance quality by which the breakage of single filament, formation of fluff, and the like are suppressed, and the operation state is stabilized in the operation of a production apparatus. SOLUTION: The flame-proofed fiber 2 having >0 and≤0.6 thickness ratio (b/a) of a double circle formed in the white-black distribution of a fiber cross section in the white-black image of the fiber cross section obtained by a scanning probe microscope observation, 1.32-1.41 specific gravity and 9-13μm fiber diameter is produced by regulating a gradient coefficient A obtained by the expression: (gradient coefficient A)=[flame-proofing treating time (min)]/(increase of specific gravity) [wherein, (increase of specific gravity)=(specific gravity of flame-proofed fiber)-(specific gravity of precursor)] so as to be≥200 when carrying out the flame-proofing treatment of the precursor for the carbon fiber, having 9.5-13.5μm fiber diameter. COPYRIGHT: (C)2007,JPO&INPIT
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