The present invention aims to provide a means by which a cured product to be obtained has a low dielectric loss tangent and higher heat resistance. Specifically, provided are an active ester compound represented by chemical formula (1): ##STR00001## (where in chemical formula (1), Ar.sup.1 is a substituted or unsubstituted first aromatic ring group, and each Ar.sup.2 is independently a substituted or unsubstituted second aromatic ring group, in which at least one of Ar.sup.1 and Ar.sup.2 has an unsaturated bond-containing substituent, and n is an integer of 2 or 3), a curable composition containing the active ester compound, and a cured product thereof.

A flexible encapsulating material, a method for preparing the flexible encapsulating material, and an encapsulating method using the flexible encapsulating material are provided. The flexible encapsulating material includes an epoxy resin represented by a Formula (1), a curing agent, and a curing accelerator and optionally includes a coupling agent, wherein based on 100 parts by weight of a total usage amount of the epoxy resin (A), the curing agent (B), and the curing accelerator (C), a usage amount of the epoxy resin (A) is 85 parts by weight or more, and based on 100 parts by weight of the usage amount of the epoxy resin (A), a usage amount of the coupling agent (D) is 0 to 5 parts by weight. ##STR00001##

The present disclosure provides a curable void filler composition comprising: (a) at least one epoxy resin; (b) at least one epoxy curing agent comprising a carboxylic acid anhydride compound; (c) at least one alkaline oxide and/or at least one alkaline earth oxide.

The present invention provides a curable composition comprising a urethane-modified epoxy resin (A) as an essential component of a main material, and an acid anhydride (B) as an essential component of a curing agent, wherein the urethane-modified epoxy resin (A) is a reaction product of a polyisocyanate compound (a1), a polyester polyol (a2), and a hydroxyl group-containing epoxy resin (a3) as essential reaction raw materials. The curable composition of the invention is advantageous in that a cured product having excellent fracture toughness and excellent tensile strength can be formed from the composition.

Provided are: a composition for powder coating materials, which enables the achievement of a cured film that has excellent thin film smoothness, electrical insulation properties and thermal conductivity; and a coated article. The present invention relates to: a composition for powder coating materials, which contains (A) a thermally conductive filler having an average circularity of 0.92 or more, (B) a thermosetting resin and (C) a curing agent; and a coated article, the surface of which is provided with a cured film that is formed from this composition for powder coating materials. The present invention also relates to a composition for powder coating materials, which additionally contains (D) a dispersant.

A curable composition to be cured to a cured product excellent in heat resistance and dielectric properties, a cured product of the curable composition, a printed wiring board, a semiconductor sealing material, and a build-up film. There is a curable composition containing an aromatic ester compound (A) and a maleimide compound (B), the aromatic ester compound (A) being represented by structural formula (1) (where in the formula, Ar.sup.1 is a substituted or unsubstituted aromatic ring group, each R.sup.1 is a polymerizable unsaturated bond-containing substituent, each 1 is 0 or 1, each R.sup.2 is any of an alkyl group, an alkoxy group, an alkyloxycarbonyl group, an alkylcarbonyloxy group, and a halogen atom, each m is 0 or an integer of 1 to 5, and n is 2 or 3, provided that at least one polymerizable unsaturated bond-containing substituent is contained in one molecule as a substituent on Ar.sup.1 or as R.sup.1).

The invention provides highly functional epoxy resins that may be used themselves in coating formulations and applications but which may be further functionalized via ring-opening reactions of the epoxy groups yielding derivative resins with other useful functionalities. The highly functional epoxy resins are synthesized from the epoxidation of vegetable or seed oil esters of polyols having 4 or more hydroxyl groups/molecule. In one embodiment, the polyol is sucrose and the vegetable or seed oil is selected from corn oil, castor oil, soybean oil, safflower oil, sunflower oil, linseed oil, tall oil fatty acid, tung oil, vernonia oil, and mixtures thereof. Methods of making of the epoxy resin and each of its derivative resins are disclosed as are coating compositions and coated objects using each of the resins.

Provided are a curable composition capable of both exhibiting a low shrinkage percentage during curing and forming a cured product having a low elastic modulus under high temperature conditions, a cured product of the curable composition, and a semiconductor encapsulating material and a printed wiring board which are produced using the curable composition. The curable composition includes an active ester compound (A) that is an esterification product of a phenolic compound (a1) and an aromatic polycarboxylic acid or an acid halide thereof (a2); and a curing agent. Also provided are a cured product of the curable composition, and a semiconductor encapsulating material and a printed wiring board which are produced using the curable composition.

An adhesive, more particularly a thermally curable, meltable, preferably pressure-sensitive adhesive, which is curable thermally from a temperature of 110 C., is storage-stable for approximately one month at 60 C. and longer than one year at 23 C., and an adhesive tape produced therefrom, comprising an epoxide-functionalized acrylonitrile/butadiene copolymer having on average more than 1.5 epoxide groups per molecule, and the ground reaction product of phthalic anhydride and diethylenetriamine, for use in the automotive industry both in bodyshell construction on oiled metal sheets and in the coating line on cathodically electrocoated or otherwise-coated metal sheets, for bonding and/or sealing, for example for hem fold bonding, for hem fold sealing, for seam sealing, for underseal bonding, for hole stopping, and much more.

Provided is an epoxy resin composition that has excellent electric characteristics (particularly low dielectric tangent), and that can achieve high adhesive strength to metal. Specifically, provided is an epoxy resin composition comprising an active ester compound and an epoxy resin having a specific structure.