CARBON FIBER FOR FIBER-REINFORCED RESIN

PROBLEM TO BE SOLVED: To provide a carbon fiber for resin reinforcement in which wettability between a matrix resin and a resin is increased, and the matrix resin is easily impregnated between fibers.SOLUTION: Provided is a carbon fiber for a fiber-reinforced resin to which an epoxy resin sizing agent is stuck, and in which an ester linkage -(-COO-) obtained by denaturing the epoxy resin sizing agent is present on the surface of the carbon fiber. The ester linkage is measured by X-ray photoelectron spectroscopy. The concentration of the carbon atoms in the ester linkage is preferably controlled to the ratio of 1.0% or more to the concentration of the total carbon atoms. 【課題】マトリックス樹脂との濡れ性を高め、繊維間にマトリックス樹脂が含浸しやすい樹脂強化用炭素繊維を提供する。【解決手段】本発明の繊維強化樹脂用炭素繊維は、エポキシ樹脂サイジング剤が付着した繊維強化樹脂用炭素繊維であって、前記炭素繊維の表面には前記エポキシ樹脂サイジング剤が変性したエステル結合(-COO-)が存在する。エステル結合はＸ線光電子分光法により測定される。エステル結合の炭素原子濃度は、全炭素原子濃度に対して１．０％以上の割合であるのが好ましい。【選択図】図１