Curable prepregs possessing enhanced ability for the removal of gases from within prepregs and between prepreg plies in a prepreg layup prior to and/or during consolidation and curing. Each curable prepreg is a resin-impregnated, woven fabric that has been subjected to a treatment to create an array of openings in at least one major surface. Furthermore, the location of the openings is specific to the weave pattern of the fabric.

The present invention pertains to a prepreg containing reinforcing fibers and an epoxy resin composition. Said prepreg is sandwiched between dies preheated to 140.degree.C. and pressurized to MPa and held for five minutes at this temperature to obtain a cured article having a GTg of at least 150.degree.C. The present invention also pertains to a fiber-reinforced composite material and a method for producing same. According to this invention, it is possible to provide a prepreg which is well suited to press-molding, particularly to high-cycle press-molding. It is also possible to provide a fiber-reinforced composite material which can be heat-cured at a lower temperature and over a shorter time than conventional methods, with which it is possible to minimize excessive flow of resin in hot-press curing, and which is resistant to performance defects such as fiber meandering and defects in surface appearance. A method for producing the same can also be provided.

An object of the present invention is to provide a resin composition that has a variety of properties required for a material for printed circuit boards such as high flame retardancy, and can attain a cured product having high moldability, high resistance against chemicals in a desmearing step, and a small coefficient of thermal expansion, a prepreg comprising the resin composition, a laminate including the prepreg, a metallic foil clad laminate including the prepreg, and a printed circuit board including the prepreg. A resin composition comprising an acrylic-silicone copolymer (A), a halogen-free epoxy resin (B), a cyanic acid ester compound (C) and/or a phenol resin (D), and an inorganic filler (E).

The invention provides a varnish produced through reaction between a compound having an amino group and a resin having a functional group capable of reacting with an amino group, and having a polycyclic structure, wherein a portion of a plurality of the functional group of the resin is caused to react with the amino group of the compound in a solvent, and also a varnish produced through reaction between a compound having a phenolic hydroxyl group and a resin having a functional group capable of reacting with a phenolic hydroxyl group, and having a polycyclic structure, wherein a portion of a plurality of the functional group of the resin is caused to react with the phenolic hydroxyl group of the compound in the solvent. The invention also provides a prepreg, a resin-coated film, a metal-foil-clad laminate, and a printed wiring board produced by use of any of the varnishes.

A fiber reinforced composite material having high interlaminar toughness and compressive strength under wet heat conditions, as well as an epoxy resin composition for production thereof and a prepreg producible from the epoxy resin composition is described. The prepreg includes at least constituents [A], [B], and [C] as specified below and reinforcement fiber, wherein 90% or more of constituent [C] exists in the depth range accounting for 20% of the prepreg thickness from the prepreg surface: [A] epoxy resin; [B] epoxy resin curing agent; and [C] polymer particles insoluble in epoxy resin.

The present invention is an epoxy resin composition characterized by containing component A (epoxy resin containing sulfur atoms in the molecule thereof); and component B (an epoxy resin composition containing an imidazole compound represented by formula (1), and at least one of the following components: component C (an imidazole compound represented by formula (2) below) or component D (an epoxy resin composition having at least one sulfur atom in the molecule. According to the present invention, it is possible to provide an epoxy resin composition which has outstanding stability when stored at room temperature, and which can be heat-cured at a relatively low temperature and over a short time, to give a resin with a high heat resistance when cured. (In formula (1), R.sup.1 represents a straight-chain or branched-chain alkyl group having 1 to 5 carbon atoms, or a hydroxymethyl group, R.sup.2 represents a straight-chain or branched-chain alkyl group having 1 to 5 carbon atoms, or a hydrogen atom.) (In formula (2), R.sup.3 represents an organic group having 1 or more carbon atoms, and R.sup.4 to R.sup.6 represent hydrogen atoms, methyl groups or ethyl groups.) ##STR00001##

To provide an epoxy resin composition that is suitable for producing optical sheets which exhibit excellent transparency, heat resistance, strength, smoothness and light resistance, and a cured product thereof.

An epoxy resin composition for optical3 sheets, the composition comprising a polyvalent carboxylic acid (A) represented by formula (I):

##STR00001## (wherein, R.sup.1's each independently represent a hydrogen atom, an alkyl group having 1 to 15 carbon atoms, or a carboxyl group; q represents the number of substituent R.sup.1's, and represents an integer from 1 to 4; and P represents any one of the following x, y and z):

##STR00002## (wherein, there may be a plural number of R.sup.2's per ring, and R.sup.2's each independently represent a hydrogen atom or a methyl group; and * represents a bonding site linked to the oxygen atom; y. A linear alkylene linker having 6 to 20 carbon atoms, with a main chain having 3 or more carbon atoms and being substituted with an alkyl group in at least one site);

##STR00003## (wherein, R's each independently represent a hydrogen atom, an alkyl group having 1 to 15 carbon atoms, or a carboxyl group; and * represents a bonding site linked to the oxygen atom, and an epoxy resin (B) having an aliphatic cyclic structure in the molecule).