| 摘要 |
PURPOSE:To obtain the titled porous semi-sintered body that can be biaxially stretched and has excellent pulling strength and smooth surfaces, by heating a polytetrafluoroethylene unsintered body at specified temperatures. CONSTITUTION:A polytetrafluoroethylene unsintered body obtained by paste extrusion or compression molding is heated at or above the melting point of the polytetrafluoroethylene sintered body to obtain the intended semi-sintered body wherein the endothermic curve on the crystal melting curve that is obtained by a differential scanning calorimeter is at 345+ or -5 deg.C, the crystal conversion that is defined by calories required for melting the unsintered, semi-sintered and sintered bodies is 0.10-0.85, preferably, 0.15-0.70, and the crystallinity measured by X-ray diffraction is 80-93%, preferably, 85-92%. |
