| abstract |
Provided are: an epoxy resin composition for fiber-reinforced composite materials, which has a good balance between storage stability and fast curing properties at high levels; a prepreg; and an epoxy resin composition which exhibits excellent mechanical characteristics as a fiber-reinforced composite material. A resin composition which contains an epoxy resin, dicyandiamide, an imidazole compound and an acidic compound, while satisfying the following conditions (a)-(c).n(a) The time until the heat flow rate reaches the peak top after the epoxy resin composition reaches 100°C is 25 minutes or less as measured by a differential scanning calorimeter at an isothermal temperature of 100°C in a nitrogen gas stream.n(b) The time until the heat flow rate reaches the peak top after the epoxy resin composition reaches 60°C is 15 hours or more as measured by a differential scanning calorimeter at an isothermal temperature of 60°C in a nitrogen gas stream.n(c) The ratio of the number of epoxy groups to the number of imidazole rings in the epoxy resin composition is from 25 to 90 (inclusive). |