| 摘要 |
<p>PURPOSE:To obtain the title calcined material suitable for filters, electrolysis diaphragms, electric wire coating compounds, etc., having a uniform pore size distribution and improved strength, permeability, and flexbility, by calcining polytetrafluoroethylene multi-ply sheets previously orientated. CONSTITUTION:100 parts by volume of polytetrafluoroethylene (PTFE) powder is blended with 15-30 parts by volume of a liquid lubicant, e.g., to toluene, and then extruded or calendered to form sheets. After the lubricant is removed from the sheets by extraction, etc., the sheets are stretched by rolls or a tenter. The stretched PTFE porous sheets are piled to prepare multi-ply sheets, which are uniformly brought into contact with adjoining sheets and calcined at not lower than 327 deg.C to give the desired porous multi-ply calcined material.</p> |
