Abstract: An epoxy resin composition for a cured material, comprising (A) an epoxy resin comprising an epoxy compound X, the epoxy compound X has an epoxy equivalent weight of at least 400, (B) a curing agent, and (C) a liquid rubber that is liquid at room temperature and comprises a reactive group; wherein the epoxy compound X has a solubility parameter value of SpX, the liquid rubber has a solubility parameter value of SpY and the ratio of SpY/SpX could be in the range of 0.7 to 1.3; and wherein the liquid rubber could form no visible domains by optical microscopy or has a maximum domain size of at most 3 microns in the cured material is described. The epoxy resin composition provides a fiber-reinforced material with higher compressive modulus and strength, toughness and better handling ability over standard epoxy resin systems. This invention is excellent for small thin walled tube structures like fishing rods or applications that require good compressive strength.

Abstract: An epoxy resin composition for a cured material, comprising (A) an epoxy resin comprising an epoxy compound X, the epoxy compound X has an epoxy equivalent weight of at least 400, (B) a curing agent, and (C) a liquid rubber that is liquid at room temperature and comprises a reactive group; wherein the epoxy compound X has a solubility parameter value of SpX, the liquid rubber has a solubility parameter value of SpY and the ratio of SpY/SpX could be in the range of 0.7 to 1.3; and wherein the liquid rubber could form no visible domains by optical microscopy or has a maximum domain size of at most 3 microns in the cured material is described. The epoxy resin composition provides a fiber-reinforced material with higher compressive modulus and strength, toughness and better handling ability over standard epoxy resin systems. This invention is excellent for small thin walled tube structures like fishing rods or applications that require good compressive strength.

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: The present invention provides a prepreg having an excellent self adhesiveness to a honeycomb core, a low porosity when used as skin panels, an excellent surface smoothness due to a low surface porosity, and good tackiness and drapability. This invention also provides a honeycomb sandwich panel having a skin panel peel strength, an excellent impact resistance and an excellent hot water resistance, and a composition for a fiber reinforced composite material made from the prepreg and honeycomb sandwich panel. The fiber reinforced composite material made from the prepreg of the present invention can be used for airplanes, automobiles and other industrial applications, particularly as structural materials of airplanes, because of its excellent mechanical properties.

Abstract: Prepregs, comprising the following components [A], [B] and [C], with the component [C] distributed near either or both of the surface layers without being regularly arranged.[A]: Long reinforcing fibers[B]: A matrix resin[C]: Long thermoplastic resin fibersThe prepregs of the present invention are tacky and drapable, and the composite materials obtained by heating and forming the prepregs are high in heat resistance, and very high in impact resistance and inter-layer toughness. Furthermore, the prepregs are easy to produce and high in their latitude in availability of materials.

Abstract: Tough laminated composite material which comprise (A) long reinforcing fibers, (B) a matrix resin mixed with the long reinforcing fibers and (C1) a resin, preferably in the form of fine resin particles, forming a phase separate from said matrix resin which is localized in inter-layer zones, wherein 90% or more of said resin (C1) is localized in inter-layer zones and/or wherein the border length factor in the inter-layer zones is 2.5 or more and prepregs used to form the composite materials.

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: The present invention relating to prepegs has the following constitution to achieve the above object. That is, a prepreg, comprising long reinforcing fibers [A], matrix resin [B] and a knitted fabric made from thermoplastic resin fibers [C], with the component [C] distributed near either or both of the surface layers. Moreover, the present invention relating to processes for production of prepregs has either of the following constitution to achieve the above object. That is, a process for preparing a prepreg, comprising the steps of impregnating long reinforcing fibers [A] with matrix resin [B], and bonding a knitted fabric made from thermoplastic resin fibers [C] onto one side or both sides of the intermediate product, or a process for preparing a prepreg, comprising the step of bonding matrix resin [B] formed as a film, a knitted fabric made from thermoplastic resin fibers [C] and long reinforcing fibers [A].

Abstract: A cured resin product has a strain energy release rate (GIC) of at least 400 J/m.sup.2, a flexural modulus of at least 300 Kg/mm.sup.2, and a glass transition temperature (Tg) of at least 120.degree. C. The cured resin composition comprises a thermoset resin component (A), optionally including a curing agent (B), and a thermoplastics resin component (C), the thermoplastics resin and thermoset resin components (C) and (A) being present at least partly in respective phases (1) and (2) each being elongate in at least one direction and each preferably having a three dimensionally continuous structure. Phase (1) may contain a silicon containing compound providing a concentration therein of elemental silicon higher than that in any other phase, and/or the cured resin product may additionally include regions where one of the phases (1) and (2) essentially surrounds the other.

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.

Abstract: A maleimide resin composition which gives a cured plastic having high toughness, high elastic modulus, high thermal resistance, high thermal decomposition resistance, low water absorption and high solvent resistance, as well as a prepreg and a fiber-reinforced plastic having the maleimide resin composition of the present invention as a matrix resin is disclosed. The maleimide resin composition of the present invention comprises a maleimide resin [A]; and a polyimide resin [B] containing a recurring unit of the formula [I] and/or [II]: ##STR1## (wherein Z represents a tetracarboxylic acid dianhydride residue) ##STR2## (wherein Z represents the same meaning as in formula [I]) said polyimide has amino groups and/or maleimide groups at the ends of the polyimide molecules.

Abstract: A prepreg and a composite prepared from the prepreg having high impact resistance, high interlayer toughness and high tensile strength are disclosed. The prepreg comprises the following elements [A], [B] and [C]:[A]: reinforcing fibers;[B]: a resin composition including a thermosetting resin and a thermoplastic resin which is soluble in said thermosetting resin, which resin composition being capable of forming a micro-phase separation structure; and[C]: fine particles which are insoluble in said element [B] and which do not contain an elastomer component;said element [C] being localized in a surface of said prepreg. The present invention also provides a composite prepared from this prepreg.

Abstract: Tough laminated composite material which comprise (A) long reinforcing fibers, (B) a matrix resin mixed with the long reinforcing fibers and (C1) a resin, preferably in the form of fine resin particles, forming a phase separate from said matrix resin which is localized in inter-layer zones, wherein 90% or more of said resin (C1) is localized in inter-layer zones and/or wherein the border length factor in the inter-layer zones is 2.5 or more and prepegs used to form the composite materials.

Abstract: A compound represented by the following general formula [1]: ##STR1## wherein R.sub.3 and R.sub.4 are independently selected from hydrogen and alkyl groups having 1 to 4 carbon groups,is valuable as an endcapping agent for a polyimide. Namely, a PMR polyimide varnish comprising this compound, a dialkyl tetracarboxylate represented by the following general formula [2]: ##STR2## wherein R.sub.1 is a direct bond or stands for CH.sub.2, O, CO, SO.sub.2, S or C(CH.sub.3).sub.2 and X stands for an alkyl group having 1 to 4 carbon atoms,and a diamine represented by the following general formula [3]: ##STR3## wherein R.sub.2 is a direct bond or stands for CH.sub.2, O, CO, SO.sub.2 S or C(CH.sub.3).sub.2,has a good storage stability and is especially valuable as a matrix resin to be incorporated in a fiber-reinforced composite material.

Abstract: Disclosed in an alicyclic end-capping agent for a heterocyclic compound, which is represented by the formula [I]: ##STR1## wherein X is CO, O, S, CH.sub.2 or substituted CH.sub.2, Y.sub.1 -Y.sub.6 are halo, H, NO.sub.2, aryl, alkaryl, arylalkyl or alkyl ether, and Z is ##STR2## (Q.sub.1 is --NH.sub.2, --SH, --OH or ##STR3## (Q.sub.2 is H, or monovalent aliphatic or amomatic group). Also disclosed is an addition-curable quinoxaline resin oligomer having the above-mentioned alicylic end-capping agents at both terminals of oligomer. This oligomer is useful especially for an intermediate material for a fiber-reinforced composite.

Abstract: Disclosed is an alicylic end-capping agent for a heterocyclic compound, which is represented by the formula [I]: ##STR1## wherein X is CO, O, S, CH.sub.2 or substituted CH.sub.2, Y.sub.1 -Y.sub.6 are halo, H, NO.sub.2, aryl, alkaryl, arylalkyl or alkyl ether, and Z is ##STR2## (Q.sub.1 is --NH.sub.2, --SH, --OH or ##STR3## (Q.sub.2 is H, or monovalent aliphatic or amomatic group). Also disclosed is an addition-curable quinoxaline resin oligomer having the above-mentioned alicylic end-capping agents at both terminals of oligomer. This oligomer is useful especially for an intermediate material for a fiber-reinforced composite.