| 摘要 |
PURPOSE:To provide the titled sealing material which is inexpensive and has excellent compression creep resistance and reliability, by orienting a substrate composed of an ultrahigh-molecular-weight thermoplastic resin at least in one direction at a specified draw ratio. CONSTITUTION:A sheet-form substrate 3 composed of an ultrahigh-molecular- weight thermoplastic resin (e.g., PE) which has a complex viscosity of not lower than 10 deg. P in shear vibration of 1 rad/sec at a temp. of (melting temp. plus 50 deg.C) and can not be easily fluidized even at a heating temp. exceeding the melting temp. is heated at a temp. of not lower than the glass transition temp., but lower than the decomposition temp. The inner surface 2 (pref. having a lubricant applied thereto) of a compression die 1 is heated at a temp. of not lower than (the skin temp. of the substrate 3 minus 100 deg.C), but lower than the decomposition temp. during the heating the heated substrate 3 is placed, compressed and oriented at least in one direction at a draw ratio of at least 3. The resulting sheet is cooled as such or kept at a fixing temp. to stabilize it and the resulting oriented sheet 4 composed of an ultrahigh-molecular-weight thermoplastic resin is then taken out. |
