FIBER-REINFORCED COMPOSITE MATERIAL

PROBLEM TO BE SOLVED: To provide a fiber-reinforced composite material with high strength.SOLUTION: The fiber-reinforced composite material is a fiber-reinforced plastic which is composed of: a fiber bundle of reinforcing fibers in which monofilament fineness of the reinforcing fibers is 1.0 to 2.4 dtex and the cross-sectional shape orthogonal to the fiber axis, of a monofilament has a roundness of 0.7 to 0.9; and a cured substance of epoxy resin composition including epoxy resin and an epoxy resin curing agent. The roundness is a value obtained by the following equation (1), and S and L are respectively the cross-sectional area and the peripheral length of the monofilament obtained through observation of the cross-sectional shape orthogonal to the fiber axis, of the monofilament of the reinforcing fibers by using an optical microscope and image analysis. Roundness=(4 S)/L...(1) 【課題】高い強度を持つ繊維強化複合材料を提供すること。【解決手段】補強繊維の単繊維繊度が１．０ｄｔｅｘ以上２．４ｄｔｅｘ以下、単繊維の繊維軸に垂直な断面形状が、真円度０．７以上０．９以下である補強繊維の繊維束と、エポキシ樹脂とエポキシ樹脂硬化剤を含むエポキシ樹脂組成物の硬化物とからなる繊維強化プラスチックである。但し、真円度は下記式（１）で求められる値であり、ＳとＬはそれぞれ、光学顕微鏡で補強繊維の単繊維の繊維軸に垂直な断面の形状を観察し画像解析から得られる単繊維の断面積と周長である。真円度=(４ Ｓ)／Ｌ２・・・・（１）【選択図】なし