Abstract: A curable composition including: (A) an ester bond-containing organosilicon compound having two or more addition reactive carbon-carbon double bonds in one molecule, shown by the following general formula (1); (B) a silicon compound having two or more silicon atom-bonded hydrogen atoms in one molecule; and (C) a hydrosilylation reaction catalyst. This provides a curable composition to give a cured product with low gas permeability as well as excellent crack resistance and light transmission property.

Abstract: A curable composition including: (A) an ester bond-containing organosilicon compound having two or more addition reactive carbon-carbon double bonds in one molecule, shown by the following general formula (1); (B) a silicon compound having two or more silicon atom-bonded hydrogen atoms in one molecule; and (C) a hydrosilylation reaction catalyst. This provides a curable composition to give a cured product with low gas permeability as well as excellent crack resistance and light transmission property.

Abstract: The invention provides a primer composition which adheres a substrate mounting an optical semiconductor device and a cured material of an addition reaction curing silicone composition that encapsulates the optical semiconductor device includes (A) an acrylic resin containing either one or both of an acrylate ester and a methacrylate ester that contains one or more SiCH?CH2 groups in the molecule, and (B) solvent. There can be provided a primer composition in which the adhesion between a substrate mounting an optical semiconductor device and a cured material of an addition reaction curing silicone composition that encapsulates the optical semiconductor device can be improved, the corrosion of a metal electrode formed on the substrate can be prevented, and the heat resistance of a primer itself can be improved.

Abstract: The invention provides a primer composition which adheres a substrate mounting an optical semiconductor device and a cured material of an addition reaction curing silicone composition that encapsulates the optical semiconductor device includes (A) an acrylic resin containing either one or both of an acrylate ester and a methacrylate ester that contains one or more SiCH?CH2 groups in the molecule, and (B) solvent. There can be provided a primer composition in which the adhesion between a substrate mounting an optical semiconductor device and a cured material of an addition reaction curing silicone composition that encapsulates the optical semiconductor device can be improved, the corrosion of a metal electrode formed on the substrate can be prevented, and the heat resistance of a primer itself can be improved.