PTFE LAYERS AND METHODS OF MANUFACTURING

摘要

Single, continuous PTFE layers having lateral zones of varied characteristics are described. Some of the lateral zone embodiments may include PTFE material having little or no nodal and fibril microstructure. Methods of manufacturing PTFE layers allow for controllable permeability and porosity of the layers, in addition to other characteristics. The characteristics may vary from one lateral zone of a PTFE layer to a second lateral zone of a PTFE layer. In some embodiments, the PTFE layers may act as a barrier layer in an endovascular graft or other medical device.

主权项

1. A method of processing PTFE, comprising:
extruding a compounded PTFE resin with a lubricating agent through an extruder in a machine direction to form a PTFE ribbon extrudate, wherein the compounded PTFE resin comprises polytetrafluoroethylene or comprises polytetrafluoroethylene and a copolymer of polytetrafluoroethylene; calendering the PTFE ribbon extrudate in the machine direction to form a planar 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; selectively applying a stretching agent to the layer of PTFE in a predetermined pattern comprising a plurality of first lateral zones within the layer of PTFE being substantially saturated with the applied stretching agent and a plurality of second lateral zones within the layer of PTFE with substantially less of the applied stretching agent; providing a tentering machine; stretching the layer of PTFE in the tentering machine in the transverse direction to the machine direction while the plurality of the first lateral zones of the layer of PTFE are fully saturated with the stretching agent throughout their thicknesses during stretching; and sintering the layer of PTFE; wherein the plurality of the first lateral zones have a shape selected from the group consisting of squares, rectangles, circles, ellipses and combinations thereof; and wherein, after stretching and sintering, the plurality of the first lateral zones of the PTFE layer have substantially no fluid permeability to low fluid permeability.