| 摘要 |
PROBLEM TO BE SOLVED: To provide a seal material capable of sufficiently suppressing permeation of gas in a keeping state of mountability and adhesiveness for a seal surface. SOLUTION: An O-ring 1 has a double structure comprising an annular base material 2 and a gas shielding film 3 formed on the surface of it. The base material 2 is made of elastic material, and the entire base material is formed of hydrogenated nitrile rubber containing less acrylonitrile (for example, 20%). The gas shielding film 3 is made of resin material with gas permeability lower than butyl rubber. As the resin material, acrylonitrile-butadiene copolymer containing 50% or more acrylonitrile is used. When the content of the acrylonitrile is high, the gas permeability becomes low but resin becomes fragile. When the film is thick, adhesiveness with the seal surface causes failure. However, the gas permeability becomes lower than a conventional O-ring even when the gas shielding film 3 is thin, so that the film is made thin to keep strength and mountability. |
