Patent ID: 8728372

Claim:
A method of processing PTFE, comprising: extruding a compounded PTFE resin through an extruder in a machine direction to form a PTFE ribbon extrudate; calendering the PTFE ribbon extrudate in the machine direction to form a layer of PTFE having an upper surface and a longitudinal length in a machine direction of an extruder used to produce the layer of PTFE and having a width in a cross-machine or transverse direction; applying an isoparaffin stretching agent to at least a portion of the upper surface of the layer of PTFE; applying the isoparaffin stretching agent on the upper surface of the layer of PTFE so that the layer of PTFE is pooled or puddled with the isoparaffin stretching agent; and stretching the layer of PTFE in the transverse direction to the machine direction while the layer of PTFE is pooled or puddled with the isoparaffin stretching agent to fully saturate the layer of PTFE throughout its thickness during stretching to form a stretched layer of PTFE that has (i) a closed cell microstructure with a plurality of interconnected high density regions of PTFE having no distinct fibrils interconnecting adjacent nodes when viewed at a magnification of 20,000 under a scanning electron microscope; and (ii) a thickness from 0.00005 inch to 0.005 inch; wherein the stretching is at a rate from 10 percent per second to 100 percent per second; wherein the stretching is performed at a stretch ratio from 7.8:1 to 13:1; and wherein stretching of the layer of PTFE is performed at a temperature of 80° F. to 100° F.