MANUFACTURE OF PREPREG

PURPOSE:To obtain a prepreg which gives a composite material excellent in heat resistance, moisture resistance, and characteristics in the direction other than that of fibers by a process comprising a plurality of specified steps to manufacture a prepreg consisting of reinforcing fibers and a matrix resin. CONSTITUTION:A prepreg consisting of reinforcing fibers and a matrix resin is manufactured by a process comprising the steps of preparing a matrix resin composition composed mainly of a bismaleimide component of formula I (wherein R is a divalent or higher aromatic residue; X1 and X2 are each H, alkyl, phenyl or halogen; n is 2 to 6) and/or a cyanic acid ester component of formula II (wherein R is an aromatic residue; m is n); heating the composition and applying it thinly on a release paper; coating reinforcing fibers (e.g. Tirano fibers, a product of Ube Kosan Co.) with an aminosilane coupling agent (e.g. gamma-aminopropyltriethoxysilane); doubling the coated reinforcing fibers on the coated release paper; and pressing the obtained sheet by means of heating rollers to infiltrate the resin into the reinforcing fibers to thereby give a prepreg.