| 摘要 |
<p>An annular gasket (1) made from porous polytetrafluoroethylene f or sanitary piping, wherein the surface layer of the inner peripheral portion (1c) which comes into direct contact with a fluid to be sealed is formed into a pore-free molten solidified layer (1'c). Though the gasket (1) is one made from the porous material, permeation leak from the gasket inner peripheral portion (1c) is prevented by the pore-free molten solidified layer (1'c) formed on the portion (1c). Moreover, because this molten solidified layer (1'c) is formed on only the surface layer of the inner peripheral portion (1c) of the gasket, the original characteristics inherent to porous polytetrafluoroethylene of the gasket as a whole, such as flexibility, compatibility, etc., are not at all deteriorated.</p> |
