| 摘要 |
PURPOSE:To improve the pore property and the mechanical strength, by preparing a film PTFE using as raw material a molding powder obtained by suspension polymerization, heating the film to or over 327 deg.C, and quenching the film so that the crystallinity is brought to or below 55%. CONSTITUTION:A powder to be used for molding of PTFE and having an average particle diameter of 1-900mum that has been obtained by suspension polymerization is compression molded followed by calcinating to produce a PTFE film, and the film is calcined again to or over 327 deg.C, preferably to 350-390 deg.C, and is quenched at a cooling speed of 70 deg.C/hr or higher so that the crystallinity of the PTFE may be lowered to or below 55%. Then the film is heated to 100- 320 deg.C, preferably 200-250 deg.C, while it is stretched, if desired biaxially, 1.3-6.5 times the original. The obtained PTFE porous film has approximately round pores, the diameter of the pores are rather uniform, and the film is excellent in mechanical strength. |
