RESIN COMPOSITION FOR SEALING ELECTRONIC PARTS, AND HYDRATION-RESISTANT MAGNESIA POWDER AND PROCESS FOR PREPARATION THEREOF

摘要

Disclosed is a hydration-resistant magnesia powder having the particle surfaces covered with a continuous and uniform coating of silica. This hydration-resistant magnesia powder is prepared by introducing a heated vapor of an organic silicate compound into a reactor of a fluidized bed of magnesia powder heated at 100 to 600 DEG C so that the concentration of the organic silicate compound is 1 to 20 mole%, and precipitating a coating of silica on the surfaces of magnesia particles by thermal decomposition and/or hydrolysis of the organic silicate compound on the surfaces of magnesia particles. The new hydration-resistant magnesia powder is highly useful for preparing resin composition for sealing electronic parts.