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: A prepreg precursor including a carbon fiber woven fabric having applied to the fabric between about 0.5 to about 10 wt % of a stabilizer material for stabilizing the structural form of the fabric. Prepregs can then be produced using the woven fabric. Undesired settlement of matrix resin from the surface of the woven fabric is thus prevented. Hence, compared with a prepreg prepared using conventional woven fabric, a prepreg prepared by using the woven fabric of the invention can hold its tackiness for a long time and can be used to produce a fiber reinforced composite material excellent in smoothness without being devoid of surface resin.

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.