Patent ID: 8153229

Claim:
An epoxy resin composition for fiber-reinforced composite materials, comprising, 100 parts by weight of an epoxy resin (A), 25 to 50 parts by weight of an amine curing agent (B) selected from aliphatic polyamines, alicyclic polyamines and aromatic polyamines; and 1 to 20 parts by weight of an organic acid dihydrazide compound (C) of a melting point of between 185 and 200° C.; and a thermosetting resin (E) that is solid at room temperature does not completely dissolve in the epoxy resin (A) at a temperature of less than 90° C. and has a softening point of 120° C. or higher, wherein the thermosetting resin (E) is dispersed in a particulate form in the epoxy resin composition; wherein the composition further comprises a thermoplastic resin (F) and the thermoplastic resin (F) is in a particle state and is dissolved at a temperature of 90° C. or higher; and wherein the fracture toughness value measured in accordance with ASTM D5045-91 after curing of the epoxy resin composition is 1.8 MPa·√m or higher.