Abstract: The phenolic resin composition for fiber-reinforced composite materials of the invention comprises at least the following constituent elements A and B of a thermoplastic resin: A: phenolic resin, B: at least one thermoplastic resin selected from polyvinyl formals, polyvinyl acetals, polyvinyl butyrals, polyvinyl pyrrolidones, polyvinyl acetates, polyvinyl alcohols, polyethylene glycols, copolymerized nylons and dimer acid polyamides. The resin composition is filmwise applied to reinforcing fibers, and the resulting film is heated under pressure whereby it is impregnated into the reinforcing fibers to give a prepreg for fiber-reinforced composite materials.

Abstract: The present invention relates to a carbon fiber prepreg. The carbon fiber prepreg of the present invention is characterized in that a carbon fiber bundle comprising a plurality of continuous carbon filaments and having a hook drop value of 10 cm or more as the degree of fiber entanglement is impregnated with a base resin mainly composed of a thermosetting resin, and that particles of 150 .mu.m or less in particle size made of a thermoplastic resin account for 20 wt % or less based on the weight of the entire prepreg and distributed at a higher concentration in the surface zone than in the inside. The carbon fiber prepreg of the present invention is good in tackiness and less changing in tackiness with the lapse of time, and can form a composite with an excellent compression interlaminar shear strength (CILS) at high temperature after moisture absorption while maintaining good impact resistance.

Abstract: Disclosed is a process of producing a prepreg which is suited for preparing honeycomb sandwich panels, by which the formation of pores in the interlayer zones in the cured composite can be reduced. The prepreg comprises a resin composition including an epoxy resin, a curing agent and a solid rubber, and a woven fabric made of reinforcing fibers, the meshes of the woven fabric being crushed such that said prepreg has a cover factor K.sub.p of 97-99.9%. Also disclosed is a reinforcing fabric comprising warps and woofs which are multifilament yarns made of carbon fibers, the widths W (mm) and finenesses D (d:denier) of the warp and woof satisfying the equation of:W=k.multidot.(D/.rho.).sup.5/9(wherein k represents 3.5.times.10.sup.-2 -10.0.times.10.sup.-2 (mm.multidot.d.sup.-5/9) and .rho. represents specific gravity of said carbon fibers), the woven fabric having a cover factor K.sub.c of 90.0-99.8%.

Abstract: Disclosed is a prepreg which is suited for preparing honeycomb sandwich panels, by which the formation of pores in the interlayer zones in the cured composite can be reduced. The prepreg of the present invention comprises a resin composition including an epoxy resin, a curing agent and a solid rubber, and a woven fabric made of reinforcing fibers, the meshes of the woven fabric being crushed such that said prepreg has a cover factor K.sub.p of 97-99.9%. Also disclosed is a reinforcing fabric comprising warps and woofs which are multifilament yarns made of carbon fibers, the widths W (mm) and finenesses D (d:denier) of the warp and woof satisfying the equation of:W=k.multidot.(D/.rho.).sup.5/9(wherein k represents 3.5.times.10.sup.-2 -10.0.times.10.sup.-2 (mm.multidot.d.sup.-5/9) and .rho. represents specific gravity of said carbon fibers), the woven fabric having a cover factor K.sub.c of 90.0-99.8%.

Abstract: Method of making a reinforcing fabric comprising warps and woofs which are multifilament yarns made of carbon fibers. The widths W (mm) and finenesses D (d:denier) of the warps and woofs satisfy the equation:W=k.multidot.(D/.rho.).sup.5/9wherein k represents 3.5.times.10.sup.-2 to 10.0.times.10.sup.-2 (mm.multidot.d.sup.-5/9) and .rho. represents specific gravity of the carbon fibers. The woven fabric has a cover factor K.sub.c of 90.0 to 99.8%. The fabric is made by treating a precursor fabric with water jets.

Abstract: Disclosed is a reinforcing fabric comprising warps and woofs which are multifilament yarns made of carbon fibers, the widths W (mm) and finenesses D (d:denier) of the warp and woof satisfying the equation of:W=k.multidot.(D/.rho.).sup.5/9(wherein k represents 3.5.times.10.sup.-2 - 10.0.times.10.sup.-2 (mm.multidot.d.sup.-5/9) and .rho. represents specific gravity of said carbon fibers), the woven fabric having a cover factor K.sub.c of 90.0-99.8%. The warps and woofs are twisted to not more than 5 turns/m.