| 摘要 |
PROBLEM TO BE SOLVED: To produce a carbon fiber having high strength characteristics, and capable of stably and cheaply providing a composite material or the like by imparting a specific precursor fiber for the carbon fiber with a flame resistance, and carbonizing the precursor fiber. SOLUTION: This carbon fiber having < 5μm average single fiber diameter, and capable of providing >=8 GPa tensile strength of a resin-impregnated strand and >=290 GPa tensile modulus of the resin-impregnated strand is obtained by spinning a copolymer comprising >=95 mol.% acrylonitrile and having 2.5-4.0 intrinsic viscosity by a wet spinning method or a dry-wet spinning method, drawing the obtained fiber in a warm water of >=70 deg.C to provide a yarn having <=100% degree of swelling, imparting a lubricant containing a silicon-based compound including a silicone resin to the obtained yarn to provide a precursor fiber having <=0.6 de single fiber size, 5-35 difference of brightnessδL by an iodide adsorption and the maximum concentration part of an element such as B and Ca for flame retardation at the surface layer part of the single fiber, imparting the precursor fiber with the flame resistance, and carbonizing the precursor fiber. |
