Patent ID: 8236410

Claim:
A preform formed by draping a planar reinforcing fiber base material laminate, the planar reinforcing fiber base material laminate formed by laminating a plurality of layers of a unidirectional reinforcing fiber base material, the unidirectional reinforcing fiber base material comprising a weave of reinforcing fiber filaments arranged in parallel in a single direction, and auxiliary fibers arranged wherein a length L whereby an auxiliary fiber arranged in at least one other direction crosses a reinforcing fiber filament of the weave of reinforcing fiber filaments, a width H of the reinforcing fiber filament, and an in-plane shear strain θ exist in a relationship expressed by equations (I) and (II) below, and additionally, wherein an adhesive resin having a glass transition temperature Tg between 0° C. and 95° C. is adhesed to a surface of the unidirectional reinforcing fiber base material on at least one side thereof, an amount of adhesive resin being between 2 g/m 2 and 40 g/m 2 and adhesed in spots, lines, or discontinuous lines, L=H /cos θ (I), 3°≦θ≦30° (II), wherein the adhesive resin adhesed to each layer of the unidirectional reinforcing fiber base material partially bonds to a facing layer of the reinforcing fiber base material over the entire surface thereof, and additionally, wherein a maximum length of each bonding joint is not less than 1 mm and not greater than the width H of the reinforcing fiber filament, wherein the preform has a reinforcing fiber volume fraction Vpf in a range of 45% to 62%.