| 摘要 |
Porous fluoropolymer films, such as PTFE films, formed by a method including the steps of (a) forming a fluoropolymer (e.g., PTFE) paste, (b) extruding, calendaring, or otherwise processing the paste to form a film extrudate, (c) causing the film extrudate to be calendared in a first directional axis, (d) subsequently calendaring the film extrudate in a second directional axis which is different from the first directional axis, (e) subsequently calendaring the film extrudate in at least one additional directional axis which is different from said first and second directional axes, thereby forming a multiaxially calendared film extrudate, (f) drying the multiaxially calendared film extrudate, and (g) radially expanding the multiaxially calendared film extrudate to form a radially oriented fluoropolymer (e.g., PTFE) film. The porous fluoropolymer films formed by this method are multiaxially oriented and exhibit isotropic strength properties.
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