Epoxy resin composition, prepreg, and fiber reinforced plastic material

An epoxy resin composition for a fiber-reinforced composite material comprising components (A), (B), (C), and (D), wherein the epoxy resin composition has a degree of cure of at least 90% after being cured at 132° C. for 2 hours and a room temperature flexural modulus of at least 4.5 GPa after being cured at 132° C. for 2 hours, wherein components (A), (B), (C), and (D) comprise:

• (A) at least 20 phr per 100 phr of total epoxy resin of at least one tetrafunctional amine-based epoxy represented by formula (1), wherein X is a divalent moiety having a molecular weight of at least 15 g/mol and R1 to R4 are each independently selected from the group consisting of a hydrogen atom, halogen atoms, C1 to C6 alkyl groups, C1 to C6 alkoxyl groups, C1 to C6 fluoroalkyl groups, cycloalkyl groups, aryl groups, and aryloxyl groups wherein these groups are optionally employed individually or different groups are optionally employed in combination as each of R1 to R4;
• (B) optionally, at most 80 phr per 100 phr of total epoxy resin of at least one epoxy resin other than component (A);
• (C) at least one amine-based curing agent, wherein components (A), (B), and (C) are each present in an amount effective to provide a molar ratio of active hydrogens:epoxy groups ranging from 0.2:1 to 0.9:1;
• and
• (D) at least one urea-based catalyst.