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.

The present invention relates to a prepreg including a fiber base material layer containing a fiber base material, a first resin layer formed on one surface of the fiber base material layer, and a second resin layer formed on the other surface of the fiber base material layer, wherein the first resin layer is a layer obtained through layer formation of a resin composition (I) containing, as a main component of resin components, an epoxy resin (A), and the second resin layer is a layer obtained through layer formation of a resin composition (II) containing, as a main component of resin components, an amine compound (B) having at least two primary amino groups in one molecule thereof and a maleimide compound (C) having at least two N-substituted maleimide groups in one molecule thereof; a laminated sheet obtained by using the prepreg; a printed wiring board; a coreless board; a semiconductor package; and a method of producing a coreless board.

A prepreg sheet (1) is formed by stacking a plurality of unit layers (10a, 10b) In the unit layers (10a, 10b), prepreg tapes (100), in which a reinforced fiber bundle is impregnated with a thermosetting matrix resin composition, are disposed in rows a plurality of times. One or more of the unit layers (10a, 10b) has a gap (G) between adjacent prepreg tapes (100), and the width thereof is 10% or less of the width of the narrower of the adjacent prepreg tapes (100).

A self-adhesive prepreg comprising a fibre reinforcement layer having a first side and a second side, wherein the first side of the fibre reinforcement layer has been pre-impregnated with a self-adhesive resin composition. The self-adhesive may be used as a structural reinforcement and is especially adapted for direct bonding to oily steel or galvanized steel in the automotive, aerospace and other sheet metal fabrication industries.

An object of the present invention is to provide a composition for forming a thermally conductive material, from which a thermally conductive material having excellent thermally conductive properties and adhesiveness can be obtained. In addition, another object of the present invention is to provide a thermally conductive material, a thermally conductive sheet, and a device with a thermally conductive layer. A composition for forming a thermally conductive material of the present invention contains a thermosetting compound A, boron nitride particles B containing boron nitride and having an average particle diameter of 25.0 μm or more, and boron nitride particles C containing boron nitride and having an average particle diameter of 15.0 μm or less, in which an oxygen atom concentration on a surface of the boron nitride particles C detected by X-ray photoelectron spectroscopic analysis is 1.5 atomic % or more.

An object is to provide an epoxy resin composition which exhibits excellent tracking resistance and additionally has excellent heat resistance with a Tg of 200° C. or higher and flame retardancy. Provided is an epoxy resin composition which contains a phosphorus-containing epoxy resin and a curing agent and has a phosphorus content of within a range of 1.0 to 1.8%, wherein the phosphorus-containing epoxy resin has a ratio (L/H) of 0.6 to 4.0 of the content of trinuclear bodies (L) to the content of hepta or higher nuclear bodies (H) measured by GPC, and is a product obtained from a novolac epoxy resin having an average number of functional groups (Mn/E) of 3.8 to 4.8 and a phosphorus compound represented by the following general formula (1) and/or general formula (2).

A thermosetting resin composition (C) of which curing can be started at a relatively low temperature in a short time and a cured product exhibits high heat resistance, the thermosetting resin composition (C) comprising an epoxy resin; an epoxy resin curing agent; and an epoxy resin curing accelerator, wherein the epoxy resin curing agent contains an imidazole-based curing agent 1 which is not encapsulated in a microcapsule and a curing agent 2 which is encapsulated in a microcapsule, and the epoxy resin curing accelerator comprises a urea derivative.

Provided is a thermosetting resin composition (C) of which curing can be started at a relatively low temperature in a short time and a cured product exhibits high heat resistance, the thermosetting resin composition (C) comprising an epoxy resin; an epoxy resin curing agent; and an epoxy resin curing accelerator, wherein the epoxy resin curing agent contains an imidazole-based curing agent 1 which is not encapsulated in a microcapsule and a curing agent 2 which is encapsulated in a microcapsule, and the epoxy resin curing accelerator comprises a urea derivative.

A molding compound is made by heat-softening, fusing and compressing strips of unidirectionally aligned filaments embedded in a thermosetting resin. The thermosetting resin is non-tacky at room temperature, which allows for easy handling, elimination of cold storage and the use of robotic manufacturing methods. Composites made by molding the molding compound have excellent, highly isotropic tensile properties.

Varnish compositions and prepregs and laminates made therefrom wherein the varnish compositions include at least one first epoxy resin and at least one second epoxy resin that includes a bisphenol-A novolac epoxy resin and a harder wherein the at least one first epoxy resin and the at least one second bisphenol-A novolac epoxy resin are present in the varnish at a weight ratio ranging from about 1:1 to about 1:3.