| 摘要 |
One embodiment of the invention provides the corundum for filling in resin comprising three components having different secondary particle sizes and specific surface areas as follows: component X of 35 to 80 mum and 1 to 0.01 m2/g; component Y of 1 to 5 mum and 3 to 0.5 m 2/g; and component Z of 0.3 to 1.5 mum and 15 to 3 m2/g, with a composition ratio by mass (X:Y:Z) being in the range surrounded by four points of (60:40:0), (95:0:5), (95:5:0) and (60:0:40) not including the borderlines in the ternary compositional diagram, and a composition obtained by filling a specific amount of the corundum into silicone oil has a viscosity of less than 2,000 poise and a linseed oil absorption of 10 ml/100 g or less. |
