The present application provides a rapid curing epoxy resin composition for fiber-reinforced plastic materials that can be used with modern fast-cure heating systems without loss of heat resistance, surface quality, or mechanical properties of the cured epoxy matrix composite as well as prepregs and fiber-reinforced plastic materials based thereon as their matrix resins. The epoxy resin composition includes an epoxy resin, a dicyandiamide, an aromatic urea, and a clathrate complex comprising at least one compound selected from the group consisting of carboxylic acid compounds and tetrakisphenol compounds and at least one epoxy accelerator which is an imidazole and/or imidazoline.

The present disclosure relates to a color-changing adhesive composition, for example, a color-changing adhesive composition suitable in the preparation of composite materials. The present disclosure also relates to methods of preparing composite materials using color-changing adhesive compositions and to composite-materials comprising such color-changing compositions.

The present invention provides low polyphenols (such as bisphenol A) tougheners for epoxy adhesives. The tougheners, and adhesives comprising the tougheners exhibit enhanced viscosity stability, e.g., compared to tougheners prepared from higher amounts of bisphenol A (and epoxy adhesives comprising them).

An epoxy resin composition for a fiber-reinforced composite material includes: (a) one or more epoxy resins; (b) an aromatic diamine compound; (c) a dicyandiamide; (d) a urea compound; and (e) an amine adduct compound, blended in specific ranges.

This coating composition for an electrical steel sheet is a coating composition for an electrical steel sheet containing an epoxy resin, a high-temperature curing agent, and inorganic fine particles, wherein a content of the high-temperature curing agent with respect to 100 parts by mass of the epoxy resin is 5 to 30 parts by mass, wherein the inorganic fine particles are one or more selected from metal hydroxides, metal oxides that react with water at 25° C. to become metal hydroxides and silicate minerals having a hydroxyl group, wherein the volume average particle diameter of the inorganic fine particles is 0.05 to 2.0 μm, wherein a content of the epoxy resin with respect to a total mass of the coating composition for an electrical steel sheet is 45 mass % or more, and wherein a content of the inorganic fine particles with respect to 100 parts by mass of the epoxy resin is 1 to 100 parts by mass.

This invention relates to a composition comprising a semisolid epoxy resin containing a curative dispersed therein. The curative has a particle size such that at least 90% of the particles have a size below 25 pm at ambient temperature of 21° C., wherein the composition further comprises a diluent containing a particulate filler. The composition is used as matrix in prepregs. The use of the diluent increases peel strength of the composition when brought into contact with metal or wood substrate.

The present application provides agents for producing an impact-modified epoxy adhesive encompassing at least two components A and B packaged separately from each other, wherein (a) component A contains at least one compound having two or more isocyanate groups together with one or more further additives, (b) component B contains at least one compound which has at least two reactive groups selected from hydroxyl groups, thiol groups, primary amino groups and secondary amino groups and is simultaneously free from epoxy groups, together with one or more further additives, (c) at least one of components A and/or B contains at least one epoxide prepolymer as an additive, (d) at least one of components A and/or B contains at least one latent hardener for epoxide prepolymers as an additive, and (e) components A and B contain no blowing agent that is capable of being heat activated.

A curable composition that can be cured at low temperature in a short time regardless of the type of epoxy compound that is mixed therewith, and has a long pot life; an adhesive comprising said curable composition; a method for producing a fiber-reinforced composite material that uses the curable composition; and a fiber-reinforced composite material containing a matrix comprising the curable composition. A curing agent mixture composition that can be cured at low temperature and in a short time, and provides the curable composition with a long pot life. An epoxy compound (A) and an imidazole compound (B) are blended in with the curable composition. In addition, the imidazole compound (B) and at least one type of crosslinking agent (C) are blended in with the curing agent mixture composition.

The present invention provides an epoxy resin-based curable composition which may be used as a structural adhesive for an automobile. Particularly, the present invention provides an epoxy resin-based curable composition having excellent low-temperature curability, while maintaining good storage stability and good adhesion. The present invention relates to a curable composition comprising an epoxy resin, a urea-based curing accelerator (A) and an amine-based curing agent (B) having a pyrazine ring.

A prepreg comprising the following constituent elements (A), (B), and (C), the constituent element (C) being present in a surface layer of the prepreg: Constituent element (A): a reinforcing fiber base material; Constituent element (B): an epoxy resin composition containing a curing agent, the epoxy resin composition being cured within the range of from 90° C. to 140° C. (inclusive); and Constituent element (C): particles of a thermoplastic resin having a melting point or a glass transition temperature within the range of from 90° C. to 140° C. (inclusive).