ENERGY-RAY-CURABLE ELASTOMER COMPOSITION, MATERIAL FOR GASKET, GASKET, AND HARD DISK DEVICE

摘要

An energy-ray-curable elastomer composition in which the molecular weight of segments between crosslinking sites can be heightened without changing the kind of uncured energy-ray-curable compound and which gives an elastomer combining breaking elongation with processability. The energy-ray-curable elastomer composition comprises (A) an energy-ray-curable compound having a (meth)acryloyl group and (B) a polythiol compound having 2 to 6 mercapto groups per molecule, and is characterized in that the ratio of the number of (meth)acryloyl functional groups in the composition to the number of mercapto functional groups in the ingredient (B) is from 100/0.1 to 100/5n (n is the number of mercapto groups per molecule of the polythiol compound). Provided is a material for gaskets, which comprises the energy-ray-curable elastomer composition and which gives a gasket having improved breaking elongation and capable of being inhibited from suffering cracking, breakage, or the like, while retaining intact processability and other necessary material properties. Also provided are: a gasket comprising an energy-ray-cured object formed from the material for gaskets; and a hard disk device including the gasket.