To provide a resin composition that is suitable for use as a matrix resin for a fiber-reinforced composite material, the resin composition exhibiting excellent impregnation properties into reinforcing fibers and rapid curing properties, giving a molded product having high heat resistance when cured, and exhibiting excellent productivity in a short time. A two-pack curable resin composition for a fiber-reinforced composite material, including a main agent that includes an epoxy resin (A) and an ester compound (B) represented by general formula (1) below, and a curing agent that includes an amine compound (C):

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(R.sub.1 and R.sub.2 each denote an alkyl group or an aryl group, and R.sub.1 and R.sub.2 may bond together to form a cyclic structure; or R.sub.1 may be an ester-containing group).

An epoxy resin composition and a cured product thereof are provided, the epoxy resin composition comprising an epoxy resin (A), a curing agent (B) comprising a compound represented by the following formula (B-1) (wherein R.sup.1 represents a hydrogen atom, a halogen atom, a methoxy group or a hydrocarbon group having 1 to 12 carbon atoms), and an imidazole adduct-type curing accelerator (C), wherein the molar ratio of the content of a phenolic hydroxide group to the content of an epoxy group in the epoxy resin composition is 0.25 to 0.67.

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The present invention provides: a two-pack curable epoxy resin composition that contains a curing agent having excellent long-term storage stability, has a low viscosity and a good impregnation property into fibers; the cured product; a fiber-reinforced composite material; and a molded article. Specifically, the two-pack curable epoxy resin composition is used, the two-pack curable epoxy resin composition containing: a main agent (i) containing an epoxy resin (A); and a curing agent (ii) containing an acid anhydride (B) and an organic phosphorus compound (C), in which a mass ratio [(i)/(ii)] of the main agent (i) to the curing agent (ii) is in a range of 35/65 to 75/25, and an amount of the organic phosphorus compound (C) used is in a range of 0.5 to 5 parts by mass with respect to 100 parts by mass in total of the epoxy resin (A) and the acid anhydride (B).

An epoxy resin B-stage film obtained by semi-curing an epoxy resin composition, the epoxy resin composition including: a liquid crystalline epoxy monomer capable of forming a cured product that includes a liquid crystal structure; and a curing agent, in which the epoxy resin B-stage film has an average thickness of less than 8 μm, and in which the liquid crystal structure included in the cured product turns into a liquid crystal structure, in which molecules are orientated in a film thickness direction, by being cured.

A prepreg having high processability and laminating performance and a method to produce such a prepreg in an industrially advantageous way is described, the prepreg comprising at least the components [A] to [E] shown below, and having a structure incorporating a first layer composed mainly of the component [A] and a first epoxy resin composition that contains the components [B] to [D] but which is substantially free of the component [E], and a second layer composed mainly of a second epoxy resin composition that contains the components [B] to [E] and which is disposed adjacent to each surface of the first layer, the second epoxy resin composition being characterized in that its component [D] has a weight-average molecular weight of 2,000 to 30,000 g/mol and accounts for 5 to 15 parts by mass relative to the total quantity of its components [B] to [E], which accounts for 100 parts by mass, [A] carbon fiber, [B] epoxy resin, [C] curing agent, [D] thermoplastic resin, and [E] particles containing a thermoplastic resin as primary component and having a volume-average particle diameter of 5 to 50 μm.

An agglomerated boron nitride powder, including a tap density of 0.6 g/ml or more and less than 0.8 g/ml and an interparticle void volume of 0.5 ml/g or more. A heat dissipation sheet, including the agglomerated boron nitride powder. An agglomerated boron nitride powder that enables a heat dissipation sheet to have improved thermal conductivity and good withstand voltage characteristics, a heat dissipation sheet containing the agglomerated boron nitride powder, and a semiconductor device including the heat dissipation sheet are provided.

A thermoplastic polymer-based composite material and a preparation method thereof are provided. The thermoplastic polymer-based composite material is obtained by impregnating a reinforcing material with a mixture or an oligomer of an epoxy resin, a bisphenol A/F, and a catalyst and then performing an in-situ polymerization. The thermoplastic polymer-based composite material is less expensive to produce, has an optimal impregnation effect, excellent secondary processing performance, high heat resistance, desirable mechanical properties and excellent overall performance.

The present disclosure relates to epoxide containing compounds comprising three benzene units linked by bridging groups. The disclosure also relates to the production of curable epoxy resin formulations comprising said epoxide containing compounds, and their possible incorporation into composite materials such as fibre reinforced composites. Possible methods for formulating the compounds epoxide containing compounds, as described herein, are also disclosed.

The present invention provides thermosetting resin pre-impregnated or infused fiber materials or prepregs comprising a fiber material of a heat resistant fiber, such as a continuous fiber material or a discontinuous chopped fiber mat, infused with a thermosetting resin mixture comprising (i) at least one liquid epoxy resin; (ii) at least one epoxy novolac resin, (iii) dicyandiamide and (iv) and an adduct of a cycloaliphatic amine and a liquid epoxy resin, wherein the dicyandiamide is dissolved in the adduct of a cycloaliphatic amine and a liquid epoxy resin. The prepreg or fiber material has a shelf life of at least 30 days at ambient temperature and pressure before its Initial Tg (DSC) rises above 40° C.

An object of the present invention is to provide an epoxy resin, an epoxy resin-containing composition, and a cured product which are excellent in flexibility. The present invention relates to an epoxy resin, which is a reaction product of an epoxy compound (A) and an acid-terminated polyester (B). In addition, the present invention relates to an epoxy resin-containing composition and a cured product obtained by using the epoxy resin.