An object of the present invention is to provide a resin composition that can attain cured products having high flame retardancy, high heat resistance, a small coefficient of thermal expansion, and high drilling processability, a prepreg having the resin composition, a laminate and a metal foil clad laminate having the prepreg, and a printed circuit board having the resin composition. A resin composition, having at least an epoxy silicone resin (A) prepared by reacting a linear polysiloxane (a) having a carboxyl group with a cyclic epoxy compound (b) having an epoxy group such that the epoxy group of the cyclic epoxy compound (b) is 2 to 10 equivalents based on the carboxyl group of the linear polysiloxane (a), a cyanic acid ester compound (B) and/or a phenol resin (C), and an inorganic filler (D).

An object of the present invention is to provide a resin composition that can attain cured products having high flame retardancy, high heat resistance, a small coefficient of thermal expansion, and high drilling processability, a prepreg having the resin composition, a laminate and a metal foil clad laminate having the prepreg, and a printed circuit board having the resin composition. A resin composition, having at least an epoxy silicone resin (A) prepared by reacting a linear polysiloxane (a) having a carboxyl group with a cyclic epoxy compound (b) having an epoxy group such that the epoxy group of the cyclic epoxy compound (b) is 2 to 10 equivalents based on the carboxyl group of the linear polysiloxane (a), a cyanic acid ester compound (B) and/or a phenol resin (C), and an inorganic filler (D).

According to the present invention, there is provide a coated film capable of exhibiting an excellent adhesion property to a prism resin used in optical applications such as a backlight unit for liquid crystal displays, etc., in particular, a prism resin adaptable for high-brightness prisms, i.e., a high-refractive index prism resin. The coating film of the present invention comprises a polyester film and a coating layer formed on at least one surface of the polyester film which is prepared from a coating solution comprising a (meth)acrylate (A) and at least one crosslinking agent (B) selected from the group consisting of an oxazoline compound, an isocyanate-based compound and a melamine compound.

According to the present invention, there is provide a coated film capable of exhibiting an excellent adhesion property to a prism resin used in optical applications such as a backlight unit for liquid crystal displays, etc., in particular, a prism resin adaptable for high-brightness prisms, i.e., a high-refractive index prism resin. The coating film of the present invention comprises a polyester film and a coating layer formed on at least one surface of the polyester film which is prepared from a coating solution comprising a (meth)acrylate (A) and at least one crosslinking agent (B) selected from the group consisting of an oxazoline compound, an isocyanate-based compound and a melamine compound.

Provided are a white heat-curable epoxy resin composition having a high strength, high toughness and superior heat resistance; and a semiconductor device whose light receiving and other semiconductor elements are encapsulated by a cured product of such composition. The composition includes: (A) a prepolymer obtained by heating, melting and mixing components (A-1) triazine derivative epoxy resin, (A-2) acid anhydride and (A-3) acrylic block copolymer so as to react them at an epoxy group equivalent in the component (A-1)/acid anhydride group equivalent of the component (A-2) ratio of 0.6 to 2.0; (B) a white pigment including at least a titanium oxide; (C) an inorganic filler; (D) a curing accelerator; and (E) an antioxidant.

Provided are a white heat-curable epoxy resin composition having a high strength, high toughness and superior heat resistance; and a semiconductor device whose light receiving and other semiconductor elements are encapsulated by a cured product of such composition. The composition includes: (A) a prepolymer obtained by heating, melting and mixing components (A-1) triazine derivative epoxy resin, (A-2) acid anhydride and (A-3) acrylic block copolymer so as to react them at an epoxy group equivalent in the component (A-1)/acid anhydride group equivalent of the component (A-2) ratio of 0.6 to 2.0; (B) a white pigment including at least a titanium oxide; (C) an inorganic filler; (D) a curing accelerator; and (E) an antioxidant.

A crystalline epoxy resin is modified to provide an epoxy resin composition capable of producing a cured product with excellent cured product properties. The modified epoxy resin composition comprises compound A having in its molecule a functional group represented by formula (1): ##STR00001##
(where each of R.sup.1 and R.sup.2 is an alkyl group, an alkenyl group, an alkynyl group, an aryl group, an aralkyl group, a heterocyclic group, or a halogenated, aminated or nitrated derivative thereof), and compound B having a glycidyl group in its molecule. The compound A is preferably a compound resulting from replacement of from at least one to at most n glycidyl groups among n glycidyl groups in a molecule (where n is an integer of from 2 to 16) with the functional group of the formula (1). The compound B is preferably a compound having n glycidyl groups (where n is an integer of from 2 to 16) in its molecule.

A crystalline epoxy resin is modified to provide an epoxy resin composition capable of producing a cured product with excellent cured product properties. The modified epoxy resin composition comprises compound A having in its molecule a functional group represented by formula (1): ##STR00001##
(where each of R.sup.1 and R.sup.2 is an alkyl group, an alkenyl group, an alkynyl group, an aryl group, an aralkyl group, a heterocyclic group, or a halogenated, aminated or nitrated derivative thereof), and compound B having a glycidyl group in its molecule. The compound A is preferably a compound resulting from replacement of from at least one to at most n glycidyl groups among n glycidyl groups in a molecule (where n is an integer of from 2 to 16) with the functional group of the formula (1). The compound B is preferably a compound having n glycidyl groups (where n is an integer of from 2 to 16) in its molecule.

Disclosed is an optical semiconductor device having an optical semiconductor mounting element including a recess. On an inner side face of the recess is a thermosetting resin composition for light reflection, which, after curing, can realize high reflectance in a range of visible light to near ultraviolet light, has excellent heat deterioration resistance and tablet moldability, and is less likely to cause burrs during transfer molding, and a process for producing the resin composition, and an optical semiconductor element mounting substrate and an optical semiconductor device using the resin composition. The heat curable resin composition for light reflection comprises a heat curable component and a white pigment and is characterized in that the length of burrs caused upon transfer molding under conditions of molding temperature of 100 C. to 200 C., molding pressure of not more than 20 MPa, and molding time of 60 to 120 sec is not more than 5 mmabd the light reflectance after heat curing at a wavelength of 350 nm to 800 nm is not less than 80%.