| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a flexible polytetrafluoroethylene resin sealing member that has high elastic recovery properties, that is, strain recovery properties, a high rate of strain recovery, and a wide elastic deformation range, while the favorable properties such as heat resistance, chemical resistance, low friction, which are proper to the resin, are substantially not damaged. <P>SOLUTION: The polytetrafluoroethylene resin sealing member has a crystallinity (as measured by a density measuring method) of not more than 70%. The polytetrafluoroethylene resin having such a crystallinity is prepared by baking, at temperatures of not less than melting point, a polytetrafluoroethylene resin comprising a tetrafluoroethylene homopolymer or a tetrafluoroethylene-perfluoroalkylvinyl ether copolymer into which the perfluoroalkylvinyl ether is copolymerized in an amount of not more than 5 mol%, so as to form a specific shape, followed by cooling it from the melting point to 270°C at a cooling rate of not less than 0.1°C/min to make the crystallinity of the resin not more than 70%. <P>COPYRIGHT: (C)2005,JPO&NCIPI |
