| 摘要 |
PURPOSE:To improve the resistance to creep and enhance the resostance to crushing, mechanical strength and corrosion-resisting sealing properties by a method wherein the material draw ratio, specific gravity and orientation release stress of an ultrahigh molecular-weight tetrafluoroethylene polymer molded item, which is stretched at least biaxially and has specified number-average molecular weight, are set to specified values. CONSTITUTION:The molded item concerned is a tetrafluoroethylene polymer (PTFE) highly oriented molded item, wherein the number-average molecular weight is 1,000,000 or more, the material draw ratio D is 3 fold or more, the specific gravity is 1.8 or more and the orientation release stress at 200 deg.C exceeds 5 kg/cm<2>. PTFE is a homopolymer of tetrafluoroethylene (TFE) or a copolymer containing 70 mol. % or more of TFE and a blending polymer threrof. As the monomer component to copolymerize with TFE, perfluoroalkyvinylether or the like is empolyed. PTFE is mainly empolyed as the matrix resin component of the item. Further, PTFE containing filler, which is blended with 50 wt% or less of reinforcing material such as glass fiber, carbon fiber or the like, is also empolyed. |
