pré-impregnado e material compósito reforçado com fibra

The invention provides a fiber reinforced composite material having high interlaminar toughness and compressive strength under wet heat conditions, as well as an epoxy resin composition for production thereof and a prepreg producible from the epoxy resin composition. The prepreg comprises at least constituents [A], [B], and [C] as specified below and reinforcement fiber, wherein 90% or more of constituent [C] exists in the depth range accounting for 20% of the prepreg thickness from the prepreg surface: [A] epoxy resin [B] epoxy resin curing agent [C] polymer particles insoluble in epoxy resin and falling under any of the following [Cx] to [Cz]: [Cx] polymer particles insoluble in epoxy resin and giving a particle diameter distribution chart meeting the following requirements from (x-i) to (x-iii): (x-i) the chart has at least two peaks, (x-ii) the particles giving the two highest peaks have a diameter ratio in the range of 1.5 to 7, and (x-iii) the one of the two highest peaks attributable to the larger-diameter particle has a half-value width in the range of 1.1 to 3, [Cy] polymer particles insoluble in epoxy resin and meeting the following requirements from (y-i) to (y-iii): (y-i) the average particle diameter is in the range of 1 to 18 µm, (y-ii) the particle sphericity is in the range of 90 to 100, and (y-iii) the glass transition temperature is in the range of 80 to 155°C, [Cz] polymer particles insoluble in epoxy resin and meeting the following requirements from (z-i) to (z-iii): (z-i) the average particle diameter is more than 12 µm and 50 µm or less, (z-ii) the particle sphericity is in the range of 90 to 100, and (z-iii) the glass transition temperature is in the range of 80 to 155°C.