Sizing agent composition for fibers, fiber bundle, fiber product and composite material

A fiber bundle comprising:

• at least one type of fiber selected from the group consisting of a carbon fiber, a glass fiber, an aramid fiber, a ceramic fiber, a metal fiber, a mineral fiber, and a slag fiber;
• an epoxy resin (A) having an aromatic ring and not having a (meth) acryloyl group and/or a reaction product of the epoxy resin (A) having an aromatic ring and not having a (meth) acryloyl group;
• a (meth) acrylate (B) and/or a reaction product of the (meth) acrylate (B), and
• a polyester resin (D) having a bisphenol skeleton and a polyoxyethylene chain, and comprising, as constituent monomers, a C8-C14 aromatic dicarboxylic acid or its anhydride and a diol having a bisphenol skeleton and a polyoxyethylene chain,
• wherein the (meth) acrylate (B) is a (meth) acrylate (B1) not having an oxyalkylene group or a (meth) acrylate (B2) having an oxyalkylene group, and
• when the (meth) acrylate (B1) is a bifunctional (meth) acrylate (B11), the bifunctional (meth) acrylate (B11) is at least one selected from the group consisting of (i) a non-aromatic di-esterified product of a C2-C20 di-to octahydric alcohol and (meth) acrylic acid, and (ii) a di-esterified product of a diglycidyl ether of a dihydric phenol and methacrylic acid;
• and
• when the (meth) acrylate (B2) is a bifunctional (meth) acrylate (B21), the bifunctional (meth) acrylate (B21) is at least one selected from the group consisting of (i) a di-esterified product of an adduct of AO with a di- to octahydric alcohol and (meth) acrylic acid, (ii) a di-esterified product of an adduct of AO with a dihydric phenol and (meth) acrylic acid, and (iii) an epoxy acrylate that is a reaction product of a diglycidyl ether of an adduct of AO with a dihydric alcohol or a dihydric phenol and acrylic acid, and
• wherein a weight ratio (epoxy resin (A) and reaction product of the epoxy resin (A)/(meth) acrylate (B) and reaction product of the (meth) acrylate (B)) of the epoxy resin (A) and the reaction product of the epoxy resin (A) to the (meth) acrylate (B) and the reaction product of the (meth) acrylate (B) in the fiber bundle is 10/90 to 90/10.