PTFE layers and methods of manufacturing
First Claim
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1. A method of processing PTFE, comprising:
- providing a layer of PTFE;
applying a stretching agent to at least a portion of the layer of PTFE; and
stretching the layer of PTFE while the layer of PTFE is wet with the stretching agent to form a stretched layer of PTFE.
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Abstract
Thin PTFE layers are described having little or no node and fibril microstructure and methods of manufacturing PTFE layers are disclosed that allow for controllable permeability and porosity of the layers. In some embodiments, the PTFE layers may act as a barrier layer in an endovascular graft or other medical device.
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Citations
58 Claims
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1. A method of processing PTFE, comprising:
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providing a layer of PTFE;
applying a stretching agent to at least a portion of the layer of PTFE; and
stretching the layer of PTFE while the layer of PTFE is wet with the stretching agent to form a stretched layer of PTFE. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22)
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23. A method of processing PTFE, comprising:
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providing a layer of PTFE;
applying a stretching agent to at least a portion of the layer of PTFE until a portion of the layer of PTFE is saturated with the stretching agent to form a saturated portion; and
stretching the layer of PTFE while the saturated portion of the layer of PTFE is saturated with the stretching agent. - View Dependent Claims (24, 25)
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26. A method of processing PTFE, comprising:
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providing a stretched layer of PTFE that has been stretched in at least a first direction;
applying a stretching agent to at least a portion of the stretched layer of PTFE;
stretching the stretched layer of PTFE while the stretched layer of PTFE is wet with the stretching agent. - View Dependent Claims (27, 28, 29, 30, 31, 32, 33, 34, 35, 36)
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37. A method of processing PTFE, comprising:
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providing a layer of PTFE;
applying a stretching agent to at least a portion of the layer;
stretching the layer of PTFE while the layer of PTFE is wet with the stretching agent to form a stretched layer of PTFE;
stretching the stretched layer of PTFE a second time; and
calendering the twice-stretched layer of PTFE so as to densify and further thin the twice-stretched layer of PTFE. - View Dependent Claims (38)
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39. A PTFE layer comprising a layer made by
providing a layer of PTFE; -
applying a stretching agent to a surface of the layer; and
stretching the layer of PTFE while the layer of PTFE is wet with the stretching agent.
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40. A PTFE layer comprising a layer made by
providing a layer of PTFE; -
applying a stretching agent to a surface of the layer;
stretching the layer of PTFE while the layer of PTFE is wet with the stretching agent; and
stretching the stretched layer of PTFE a second time.
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41. A PTFE layer comprising a layer made by
providing a layer of PTFE; -
applying a stretching agent to a surface of the layer;
stretching the layer of PTFE while the layer of PTFE is wet with the stretching agent;
stretching the stretched layer of PTFE a second time; and
calendering the twice-stretched layer of PTFE so as to densify and further thin the twice-stretched layer of PTFE. - View Dependent Claims (45)
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42. A thin PTFE layer comprising substantially low porosity, low permeability,
no discernable node and fibril structure, and having a thickness of about 0.00005 inch to about 0.005 inch.
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43. A composite PTFE film comprising:
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a first layer comprising a stretched layer of PTFE that has a closed cell microstructure with a plurality of interconnected high density regions having no discernable node and fibril microstructure between the high density regions; and
a second layer of expanded PTFE which is secured to the first layer and which includes a substantial node and fibril microstructure.
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44. A thin, substantially liquid-impermeable PTFE layer produced by:
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providing a PTFE layer;
adding a stretching agent to the PTFE layer; and
stretching the PTFE layer in at least one direction to reduce a thickness of the PTFE layer without substantially creating a liquid permeability in the stretched PTFE layer.
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46. A multi-layered vascular graft comprising:
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a first tubular body having an outer surface and an inner surface that defines an inner lumen of the vascular graft; and
a second tubular body having an outer surface and an inner surface coupled to the outer surface of the first tubular body, wherein one of the first tubular body and the second tubular body comprises a fluid-permeable PTFE layer and the other tubular body comprises a PTFE layer having low fluid permeability. - View Dependent Claims (47, 48)
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- 49. An inflatable endovascular graft comprising a body portion having an inflatable channel that defines an inflatable space, wherein the inflatable space is at least partially surrounded by a thin, PTFE layer having substantially no fluid permeability.
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52. A stretched, PTFE layer that comprises a closed cell microstructure having high density regions whose grain boundaries are directly interconnected to grain boundaries of adjacent high density regions and having no discernable node and fibril microstructure and having substantially no fluid permeability.
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53. A composite film comprising a fluid-permeable, expanded PTFE layer secured to a surface of a thin stretched PTFE layer having a closed cell microstructure having high density regions whose grain boundaries are directly interconnected to grain boundaries of adjacent high density regions and having no discernable node and fibril microstructure.
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54. A tubular structure comprising a composite film comprising a fluid-permeable, expanded PTFE layer secured to a surface of a thin, stretched PTFE layer having a closed cell microstructure having high density regions whose grain boundaries are directly interconnected to grain boundaries of adjacent high density regions and having no discernable node and fibril microstructure.
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55. An endovascular graft comprising a composite film with a fluid-permeable, expanded PTFE layer secured to a surface of a thin stretched PTFE layer having a closed cell microstructure having high density regions whose grain boundaries are directly interconnected to grain boundaries of adjacent high density regions and having no discernable node and fibril microstructure.
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56. A thin PTFE layer, comprising substantially low porosity, low liquid permeability, no discernable node and fibril structure, and a high degree of limpness and suppleness so to allow mechanical manipulation or strain of the PTFE layer without significant recoil or spring back.
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57. A thin layer of PTFE comprising a stretched layer of PTFE that has a closed cell microstructure with a plurality of interconnected high density regions having no discernable node and fibril microstructure between the high density regions.
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58. A method of controlling the porosity, density or both of a PTFE layer, comprising:
stretching the PTFE layer at least one time at a preselected temperature while using a preselected stretching agent content for the at least one stretch.
Specification