| 摘要 |
The present invention relates to an epoxy resin composition used for cap seal of a hard disc drive spindle motor, which hardly causes outgassing even when using in a hard disc for high-speed rotation and has high reliability. The composition comprises an epoxy resin having at least one glycidyl group in a molecule as a component (A), a monomer having at least one unsaturated bond group in a molecule (polyfunctional vinyl monomer or monofunctional vinyl monomer) as a component (B), an epoxy resin curing agent as a component (C), a photopolymerization initiator as a component (D), and a partially-esterified unsaturated epoxy resin wherein 10-90% of an epoxy equivalent of a bisphenol type epoxy resin is (meth)acrylated as a component (E).
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