Sizing agents used for reinforcing fibers and reinforcing fiber strands are created by coating them with sizing agents used for reinforcing fibers.

Abstract

The invention relates to a sizing agent with good high-temperature stability at high concentrations, a fiber-reinforced with this sizing agent, and a fiber-reinforced composite made of this fiber-reinforced with this sizing agent. The sizing agent for this fiber-reinforced material contains chemical compound A and chemical compound B, represented by the general formula (Chem). 1); in which chemical compound A contains at least one compound selected from the group including aromatic polyester resins AI and chemical compound A2 containing an unsaturated ethylene group, aromatic polyester resins AI containing structural units I and I1, the unsaturated ethylene group is at least one group selected from the group including vinyl ester group, acrylate group and methacrylate group, and the amount of chemical compound A is at least 10% by weight of the non-volatile component of the sizing agent used for the old-fashioned fiber.