Patent ID: 8877330

Claim:
A fiber-reinforced composite sheet comprising continuous reinforcing fibers; a thermosetting resin layer containing a partially or fully cured epoxy resin composition as a major component; and a thermoplastic resin layer containing thermoplastic resin as a major component; wherein the epoxy resin composition comprises (i) a combination of phenol novolak epoxy resin and bisphenol A epoxy resin or a combination of phenol novolak epoxy resin and bisphenol F epoxy resin, (ii) dicyandiamide curing agent, (iii) a curing accelerator having 2 or more urea bonds per molecule; and (iv) a phosphorous flame-retardant; wherein at least a portion of the reinforcing fibers are embedded in the thermosetting resin layer; wherein at least a portion of the reinforcing fibers are embedded in the thermoplastic resin layer; wherein the thermosetting resin layer and the thermoplastic resin layer are thermally bonded along an uneven interface within the fiber-reinforced composite sheet; wherein test pieces of the fiber-reinforced composite sheet having a substantial thickness of the sheet exhibit a flame retardance in accordance with UL-94 of V-1 or V-0; and wherein test pieces of the fiber reinforced composite sheet exhibit a Tmax−Tg≦5, where Tg represents the glass transition temperature of the fiber-reinforced composite sheet prior to an after-cure treatment, and Tmax represents the glass transition temperature of the fiber-reinforced composite sheet not exhibiting a residual exotherm by DSC evaluation after said after-cure treatment, wherein the after-cure treatment is performed in a temperature range of Tg to Tg+30.