PTFE material with aggregations of nodes

• US 7,306,841 B2
• Filed: 09/20/2004
• Issued: 12/11/2007
• Est. Priority Date: 08/12/1999
• Status: Expired due to Term

• Current Assignee: Bridger Biomed, Inc. (Becton, Dickinson & Co)
• Original Assignee: Bridger Biomed, Inc. (Becton, Dickinson & Co)
• Inventors: Ruefer, Rebecca U., Ruefer, Bruce G., Sharber, N. Joe, Marlow, Leonard G. Jr.
• Primary Examiner(s): GRAY, JILL M
• Application Number:
  US10/945,520
• Publication Number:
  US 20050153121A1
• Time in Patent Office: 1,177 Days
• Field of Search: 428/317.9, 428/204, 428/316.6, 428/306.4, 428/317.5, 428/317.7, 428/422, 428/421
• US Class Current: 428/317.9
• CPC Class Codes: C08J 2327/18 Homopolymers or copolymers of tetrafluoroethylene
• CPC Class Codes: C08J 5/00 Manufacture of articles or shaped materials containing macromolecular substances manufacture of semi-permeable membranes B01D67/00 - B01D71/00
• CPC Class Codes: Y10T 428/24992 Density or compression of components
• CPC Class Codes: Y10T 428/249953 Composite having voids in a component [e.g., porous, cellular, etc.]
• CPC Class Codes: Y10T 428/249964 Fibers of defined composition
• CPC Class Codes: Y10T 428/249978 Voids specified as micro
• CPC Class Codes: Y10T 428/249981 Plural void-containing components
• CPC Class Codes: Y10T 428/249986 Void-containing component contains also a solid fiber or solid particle
• CPC Class Codes: Y10T 428/3154 Of fluorinated addition polymer from unsaturated monomers
• CPC Class Codes: Y10T 428/31544 Addition polymer is perhalogenated

Abstract

A novel polytetrafluoroethylene (PTFE) material includes a plurality of aggregates connected together by a plurality of relatively long fibrils. Each of the aggregates are formed of PTFE nodes that are connected together by relatively short fibrils. Preferably, the long fibrils have lengths of 500 to 1000 microns and the short fibrils have a lengths of 10 to 30 microns. The aggregates have densities of less than 2.0 grams per cubic centimeter which is lower than the densities of the solid PTFE nodes which have densities of about 2.0 to 2.2 grams per cubic centimeter.

Claims

1. A composite expanded polytetrafluoroethylene article comprising:

at least one layer of a first polytetrafluoroethylene material including a first plurality of nodes interconnected by a first plurality of short fibrils;

at least one layer of a second polytetrafluoroethylene material including a plurality of aggregates of nodes and fibrils, each of the aggregates comprising a second plurality of nodes interconnected by a second plurality of short fibrils; and

a plurality of long fibrils interconnecting the aggregates in the at least one layer of a second polytetrafluoroethylene material and connecting the aggregates in the at least one layer of a second polytetrafluoroethylene material with selected ones of the first plurality of nodes in the at least one layer of a first polytetrafluoroethylene material.

2. The composite article of claim 1 wherein each of the first plurality of fibrils has an average length of about 10-100 microns.

3. The composite article as recited in claim 1 wherein each of the second plurality of fibrils has an average length of about 10-100 microns.

4. The composite article of claim 1 wherein each of the plurality of long fibrils has an average length of about 100 to 1000 microns.

5. The composite article of claim 4 wherein each of the plurality of long fibrils has an average length of about 500-1000 microns.

6. The composite article of claim 1 wherein the first and second plurality of short fibrils and the plurality of long fibrils are all formed by radial expansion.

7. The composite article of claim 1 wherein each of the first plurality of nodes has a density of about 2.0-2.2 grams per cubic centimeter.

8. The composite article of claim 1 wherein each of the plurality of aggregates has a density of less than 2.0 grams per cubic centimeter.

9. The composite article of claim 1 wherein each of the second plurality of nodes has a density of about 2.0-2.2 grams per cubic centimeter.

10. The composite article of claim 1 wherein the first polytetrafluoroethylene material is highly expandable relative to the second polytetrafluoroethylene material.

11. The composite article of claim 10 wherein the first polytetrafluoroethylene material includes a greater molecular weight than the second polytetrafluoroethylene material such that the first polytetrafluoroethylene material is more expandable than the second polytetrafluoroethylene material.

12. The composite article of claim 1 wherein the first polytetrafluoroethylene material is formed from particles of a first size and the second polytetrafluoroethylene material is formed from particles of a second size smaller than the first size such that the first polytetrafluoroethylene material is more expandable than the second polytetrafluoroethylene material.