| 摘要 |
PROBLEM TO BE SOLVED: To obtain a resin molding having excellent water resistance by forming a resin composition containing a thermosetting resin and a spherical fused silica powder into a molding having a specified dielectric loss tangent at a specified water absorbency. SOLUTION: This molding is obtained by mixing a mixture prepared by mixing 1 equivalent of an epoxy resin (e.g. bisphenol A epoxy resin) having an epoxy equivalent of about 170-500 with about 0.6-1 equivalent of a curing agent (e.g. phthalic anhydride/tetrahydrophthalic anhydride) with about 50-70wt.%, based on the composition, spherical fused silica particles having a mean particle diameter of about 35μm or below, especially about 3-20μm and a specific surface area of about 10m<2> /g or below, especially about 3m<2> /g or below and 10wt.% or below, based on the whole filler, another filler (e.g. alumina or glass fiber), melt-kneading the resulting mixture in a vacuum to form a casting resin composition, pouring this composition into a mold, and molding it to obtain a resin molding for electrical insulation having a dielectric loss tangent of 0.5×10<-2> or below at a water absorbency of 0.5% and showing a surface resistance of 50×10<5> to 3,000×10<5>Ωand a permittivity of 7 or below when subjected to the fluorine vapor exposure test (48-hr exposure to a 30% fluorine vapor). |
