Provided is a thermosetting resin composition including an epoxy resin and thermally conductive particles. A thermal conductivity λ.sub.200 at 200° C. of a cured product obtained by heating the thermosetting resin composition at 200° C. for 90 minutes is 12 W/(m.Math.K) or higher. In addition, a volume resistivity R.sub.200 of the cured product at 200° C. is preferably 1.0×10.sup.10 Ω.Math.m or more. In addition, a resin sheet using this thermosetting resin composition is provided. Furthermore, a metal base substrate using this thermosetting resin composition is provided.

A slightly colored or completely colorless epoxy resin composition includes an epoxy resin containing two or more epoxy groups in one molecule, a thiol compound containing two or more thiol groups in one molecule, and an amine compound, that forms a cured product having an a* value of −15 to 15 and a b* value of −15 to 15 as chromaticity features according to the color system.

The purpose of the present invention is to provide: an epoxy resin composition which enables the achievement of a resin cured product that has high flame retardancy and excellent mechanical characteristics; and a prepreg and a fiber-reinforced composite material, each of which uses this epoxy resin composition. One embodiment of the epoxy resin composition according to the present invention, said epoxy resin composition having achieved the above-described purpose, contains the components (A) and (B) described below. (A): a bifunctional glycidyl amine type epoxy compound (B): an epoxy compound having a specific structure and/or an epoxy compound having another specific structure

Provided are a resin composition for encapsulation that is superior in high-temperature reverse bias test (HTRB test) reliability; and a semiconductor device. The resin composition for encapsulation is used to encapsulate a power semiconductor element made of Si, SiC, GaN, Ga.sub.2O.sub.3 or diamond, and a cured product of the resin composition for encapsulation has a dielectric tangent of not larger than 0.50 when measured at 150° C. and 0.1 Hz. The semiconductor device is such that a power semiconductor element made of Si, SiC, GaN, Ga.sub.2O.sub.3 or diamond is encapsulated by the cured product of the resin composition for encapsulation.

A prepreg having excellent tackiness as well as excellent resin strength after curing and strength in the non-fiber direction is described; and a fiber-reinforced composite material using the prepreg, where the prepreg is composed of reinforcing fibers and a resin composition which includes [A] an epoxy resin, [B] a dicyanamide and [C] a compound having a melting point of 130° C. or lower and a solubility parameter whose difference from the solubility parameter of [B] is 8 or less.

The present invention provides a two-part thermal conductive epoxy adhesive composition with high bonding strength and low modulus. The present invention also provides a preparing method and use thereof.

Provided is an amorphous epoxy fiber excellent in dimensional stability, a fiber structure comprising at least in part amorphous epoxy fibers, and a molded body formed by melting said fibers. The amorphous epoxy fiber has a birefringence value of 0.005 or lower. For example, the amorphous epoxy fiber may include an amorphous epoxy resin represented by the following general formula:

##STR00001## in which, X is a residue of a bivalent phenol and n is 20 or greater (preferably 20 to 300, more preferably 40 to 280, still more preferably 50 to 250). The amorphous epoxy fiber may have an average fiber diameter of single fibers of 40 μm or smaller.

A curable, one-part epoxy/thiol resin composition comprising: an epoxy resin component comprising an epoxy resin having at least two epoxide groups per molecule; a thiol component comprising a polythiol compound having at least two primary thiol groups; a nitrogen-containing catalyst for the epoxy resin; and a substituted barbituric acid soluble in the one-part epoxy/thiol resin composition.

A rubber composition exhibiting an improved processability/stiffness compromise is based on at least a diene elastomer, a reinforcing filler, a crosslinking system, between 1 and 30 parts by weight per hundred parts by weight of elastomer, phr, of an epoxy resin and between 1 and 15 phr of a specific amine-comprising hardener comprising in particular at least two primary amine functional groups located on at least one six-membered aromatic ring and at least two Ri radicals, which are identical or different, selected from the group consisting of linear or branched C.sub.1-C.sub.6 alkyl radicals, halogens, and ethers, tertiary amines, thioethers, ketones, esters and amides, substituted by linear or branched C.sub.1-C.sub.6 alkyl radicals, the said ring not comprising a hydrogen atom located in the ortho position with respect to the primary amine functional groups.

A multi-epoxidized biphenyl compound has the formula (I) below ##STR00001##
wherein R, R.sub.1, R.sub.2 and R.sub.3 are as defined in the description, as well as mixtures of at least two of the compounds. These multi-epoxidized biphenyl compounds are fully suitable as main constituents of thermosetting epoxy resins, i.e. as polyepoxides precursors. They are beneficial substitutes for bisphenol A diglycidyl ether.