Epoxy resin composition, fiber-reinforced composite material, and method for producing the same

A method for producing fiber-reinforced composite material, comprising:

• placing a fiber substrate composed of reinforcing fibers on a substrate;
• attaching a binder to the fiber substrate;
• mixing at least (i) an epoxy resin base composition and (ii) at least one liquid diamine curing agent to form an epoxy resin composition;
• impregnating the fiber substrate and binder with the epoxy resin composition;
• and thermally curing the epoxy resin composition;
• wherein the epoxy resin composition comprises at least the following components (A), (B), and (C);
• wherein:
• (A) is an epoxy resin base composition comprising at least one bifunctional epoxy resin represented by any one of the following formulas (I), (II), and (III):
• wherein R1 to R17 are each independently a substituent selected from among hydrogen, halogens, and C1 to C4 alkyl groups;
• (B) is at least one liquid aromatic diamine curing agent represented by any one or more of the following formulas (IV) to (VI):
• wherein R18 to R29 are each independently a substituent selected from among hydrogen, halogens, and C1 to C4 alkyl groups;
• (C) comprises core-shell polymer particles, wherein the core-shell polymer particles as the component (C) contain epoxy groups in their shell and have a volume-average particle size of 50 to 300 nm;
• and
• wherein the at least one liquid diamine curing agent further comprises a diaminosulfone comprising a mixture of 3,3′-diaminodiphenylsulfone and 4,4′-diaminodiphenylsulfone.