| 摘要 |
PURPOSE:To prepare the titled composition having remarkably improved thermal history deterioration caused by the thermal history in the presence of a rubber or a plastic, and suitable for the peripheral parts of automobile engine, etc., by compounding ultra-fine calcium carbonate and a curing agent to a silicone rubber compound. CONSTITUTION:The objective composition is prepared by kneading (A) 100pts. of a silicone rubber compound obtained e.g. by adding a reinforcing silica filler to a diorganopolysiloxane of formula (R is univalent hydrocarbon group; a is 1.95-2.04), with (B) 0.1-10pts. of ultra-fine calcium carbonate having an average particle diameter of <=0.3mum and a specific surface area of >=3.0m<2>/g and essentially free of surface treatment, and (C) a sufficient amount (amount added to the RTV rubber, etc.) of a curing agent (e.g. organic peroxide) to cure the silicone rubber compound. When the composition is cured by heating at 50-400 deg.C and if necessary subjecting to the secondary vulcanization at 120-250 deg.C, an elastomer having excellent heat resistance can be obtained without lowering the characteristics of the silicone rubber. |
