Abstract: A prepreg containing at least the following components [A]-[F], wherein the ratio Ne/Nd of the number of structures Ne of component [F] present in a range of outside 110% of the particle diameter of component [E] and the number of structures Nd of component [F] present in a range outside 110% of the particle diameter of component [D] is 0.25 or higher. [A]: Carbon fibers, [B] thermosetting resin, [C]: curing agent, [D]: particles composed mainly of thermoplastic resin having a primary particle number-average particle size of 5-50 ?m, [E]: conductive particles different from component [D] and having a primary particle number-average particle size in the range of a specific expression, [F]: filler comprising a carbon material.

Abstract: The present invention relates to an epoxy resin composition including at least an appropriate type of epoxy resin, acid anhydride, salt of either diazabicycloundecene or diazabicyclononene and an organic compound, and core shell polymer particles, having a viscosity of 3,000 mPa·s or less at 25° C., and showing a viscosity of 4,500 mPa·s or less 3 hours after the start of measurement when subjected to continued measurement for 3 hours at a temperature of 25° C., by means of which it provides an epoxy resin composition with both a low viscosity and long pot life that serves effectively to produce fiber reinforced composite material with a high heat resistance and high toughness.

Abstract: A curable resin composition, which contains, with respect to 100 parts of an epoxy resin, 1 to 70 parts of an epoxy resin curing agent and 1 to 50 parts of an acrylic block copolymer, and the acrylic block copolymer contains (?) at least one polymer block A composed of a structural unit derived from an alkyl methacrylate and at least one polymer block B composed of a structural unit derived from an alkyl acrylate, has a weight average molecular weight (Mw) of 30,000 to 300,000 and a molecular weight distribution (Mw/Mn) of 1.5 or less, and contains 3 to 60 percent by mass of the polymer block A. In addition, a cured resin is formed from the above curable resin composition.

Abstract: The present invention provides a prepreg comprising a reinforcement fiber [A], an epoxy resin [B] having two or more epoxy groups per molecule, a compound [C] capable of curing component [B], crosslinked resin particles [D] having a refractive index in the range of 1.49 to 1.61, and carbon black [E]. Furthermore, the surface layer of the prepreg that occupies 10% of the average prepreg thickness from each surface of the prepreg comprises components [B] to [E], and the refractive index, n0, of a cured epoxy resin produced by curing a resin composition comprising component [B] and component [C] and the refractive index, n1, of component [D] have the following relationship: 0.92?n1/n0?1.05. Thus, the invention provides a prepreg that can produce fiber reinforced composite materials having decorative surfaces with decreased appearance irregularities and accordingly serves to manufacture fiber reinforced composite materials having excellent appearance.

Abstract: [Object] A curable epoxy resin composition is provided which is excellent in toughness, is hardly fractured, is strongly adhered to another material, and is also excellent in weather resistance, chemical resistance, and the like while maintaining excellent heat resistance, elastic modulus, and the like inherent to an epoxy resin. [Solution] A curable resin composition contains, with respect to 100 parts of an epoxy resin, 1 to 70 pars of an epoxy resin curing agent and 1 to 50 parts of an acrylic block copolymer, and the acrylic block copolymer contains (?) at least one polymer block A composed of a structural unit derived from an alkyl methacrylate and at least one polymer block B composed of a structural unit derived from an alkyl acrylate, has a weight average molecular weight (Mw) of 30,000 to 300,000 and a molecular weight distribution (Mw/Mn) of 1.5 or less, and contains 3 to 60 percent by mass of the polymer block A. In addition, a cured resin is formed from the above curable resin composition.