There is provided a resin composition which has long-term heat resistance, rapid curing properties, high adhesive strength during heating, a low change ratio of adhesive strength, and a low normal temperature elastic modulus. The resin composition includes (A) a compound having in its molecule an OH group and any one of primary to tertiary amines, (B) dicyandiamide and/or imidazoles, (C) bismaleimides, and (D) a compound having in its molecule one or more epoxy groups, or cyanate ester.

The present disclosure provides a liquid curing agent composition comprising at least 50% by weight of a polyamine and 0.2% to 10% by weight of dicyandiamide, the amine/epoxy composition and the product from the cured amine/epoxy composition.

The present disclosure provides a liquid curing agent composition comprising at least 50% by weight of a polyamine and 0.2% to 10% by weight of dicyandiamide, the amine/epoxy composition and the product from the cured amine/epoxy composition.

A curable composition according to the present invention for sealing optical semiconductor includes components (A), (B), and (C). Another curable composition according to the present invention for sealing optical semiconductor further includes a component (D) in addition to the components (A), (B) and (C). The component (A) is a compound containing at least one functional group selected from the group consisting of epoxy groups, oxetanyl groups, vinyl ether groups, and (meth)acryloyl groups. The component (B) is a cycloaliphatic epoxy compound. The component (C) is a curing catalyst including a cationic component and an anionic component and generating an acid upon application of light or heat, where the cationic component contains an aromatic ring, and the anionic component contains a central element selected from boron and phosphorus. The component (D) is conductive fiber-bearing particles each including a particulate substance and a fibrous conductive substance lying on or over the particulate substance.

A curable composition according to the present invention for sealing optical semiconductor includes components (A), (B), and (C). Another curable composition according to the present invention for sealing optical semiconductor further includes a component (D) in addition to the components (A), (B) and (C). The component (A) is a compound containing at least one functional group selected from the group consisting of epoxy groups, oxetanyl groups, vinyl ether groups, and (meth)acryloyl groups. The component (B) is a cycloaliphatic epoxy compound. The component (C) is a curing catalyst including a cationic component and an anionic component and generating an acid upon application of light or heat, where the cationic component contains an aromatic ring, and the anionic component contains a central element selected from boron and phosphorus. The component (D) is conductive fiber-bearing particles each including a particulate substance and a fibrous conductive substance lying on or over the particulate substance.

Amine-epoxy curing agents are disclosed including at least one saturated heterocyclic compound having two nitrogen heteroatoms according to formula (I) and at least one saturated fused bicyclic heterocyclic compound having three nitrogen heteroatoms according to formula (II):

##STR00001##

wherein X is independently selected from a hydrogen atom, a linear or branched C.sub.1 to C.sub.4 alkyl group and a substituted or un-substituted phenyl group, Y.sub.1 is a direct bond or a divalent polyethylene polyamine group having 1 to 8 nitrogen atoms or a divalent polyethylene polyamine derivative having 1 to 8 nitrogen atoms, Y.sub.2 is a direct bond or a divalent polyethylene polyamine group having 1 to 7 nitrogen atoms and R is independently a hydrogen atom or a group selected from C.sub.1-C.sub.8 linear, cyclic, and branched alkyl, alkenyl, and alkaryl groups.

Amine-epoxy curing agents are disclosed including at least one saturated heterocyclic compound having two nitrogen heteroatoms according to formula (I) and at least one saturated fused bicyclic heterocyclic compound having three nitrogen heteroatoms according to formula (II):

##STR00001##

wherein X is independently selected from a hydrogen atom, a linear or branched C.sub.1 to C.sub.4 alkyl group and a substituted or un-substituted phenyl group, Y.sub.1 is a direct bond or a divalent polyethylene polyamine group having 1 to 8 nitrogen atoms or a divalent polyethylene polyamine derivative having 1 to 8 nitrogen atoms, Y.sub.2 is a direct bond or a divalent polyethylene polyamine group having 1 to 7 nitrogen atoms and R is independently a hydrogen atom or a group selected from C.sub.1-C.sub.8 linear, cyclic, and branched alkyl, alkenyl, and alkaryl groups.

Provided is an epoxy resin which has a low viscosity and excellent impregnation capability into reinforcing fibers and provides a cured product having a high elastic modulus and excellent heat resistance when the epoxy resin is used for a fiber-reinforced resin material, and a method for producing the epoxy resin, a curable resin composition, and a cured product thereof, a fiber-reinforced composite material, and a molded article. An epoxy resin which is polyglycidyl ether that is a polycondensation product of phenol and hydroxybenzaldehyde, the resin includes the trinuclear body (X) represented by the following Structural Formula (1), in which the content of a [o,p,p] bonding body (x1) represented by the following Structural Formula (1-1) among the trinuclear body (X) is in the range of 5% to 18% in terms of an area ratio as measured by liquid chromatography.

##STR00001##

Provided is an epoxy resin which has a low viscosity and excellent impregnation capability into reinforcing fibers and provides a cured product having a high elastic modulus and excellent heat resistance when the epoxy resin is used for a fiber-reinforced resin material, and a method for producing the epoxy resin, a curable resin composition, and a cured product thereof, a fiber-reinforced composite material, and a molded article. An epoxy resin which is polyglycidyl ether that is a polycondensation product of phenol and hydroxybenzaldehyde, the resin includes the trinuclear body (X) represented by the following Structural Formula (1), in which the content of a [o,p,p] bonding body (x1) represented by the following Structural Formula (1-1) among the trinuclear body (X) is in the range of 5% to 18% in terms of an area ratio as measured by liquid chromatography.

##STR00001##

The present disclosure provides a curable adhesive composition precursor, comprising a first part (A) comprising (i) at least one first epoxy curing agent selected from diamines: (ii) at least one second epoxy curing agent selected from phenalkamides and/or phenalkamines: (iii) at least one first curing aid selected from metal salt hydrates: (iv) at least one second curing aid selected from phenolic amines: a second part (B) comprising (i) at least one epoxy resin: (ii) at least one first impact modifier; (iii) at least one second impact modifier different from the at least one first impact modifier: (iv) at least one amphoteric corrosion inhibitor selected from phosphonate compounds and phosphosilicate compounds.