Kohlenstoffasern, und Verfahren zu deren Herstellung

摘要

Carbon fibers with a surface oxygen concentration (O/C ratio) of 0.20 or less as measured by X-ray photoelectron spectroscopy and (a) a surface concentration of hydroxyl groups (C-OH/C ratio) of 0.5% or greater as measured by chemical modification X-ray photoelectron spectroscopy and a surface concentration of carboxylic groups (COOH/C ratio) of 2.0% or less as measured by chemical modification X-ray photoelectron spectroscopy, or (b) a surface nitrogen concentration (N/C ratio) of 0.02 or greater, as measured by X-ray photoelectron spectroscopy, additionally comprise, as a sizing agent, an aliphatic compound which has multiple epoxy groups or an aromatic compound which has multiple epoxy groups, the number of atoms between the epoxy groups and an aromatic ring being 6 or greater. They are prepared by electrolyzing a carbon fiber in an alkaline aqueous solution, or electrolyzing a carbon fiber in an acidic aqueous solution followed by washing with an alkaline aqueous solution, and then applying a sizing agent of an aliphatic compound with multiple epoxy groups or an aromatic compound with multiple epoxy groups in which the number of atoms between the epoxy groups and an aromatic ring is 6 or greater. Alternatively, they are prepared by electrolyzing a carbon fiber in an aqueous solution of an ammonium salt and then applying a sizing agent of an aliphatic compound with multiple epoxy groups or an aromatic compound with multiple epoxy groups in which the number of atoms between the epoxy groups and an aromatic ring is 6 or greater.