Green fluoropolymer tube and endovascular prosthesis formed using same

• US 7,597,775 B2
• Filed: 10/30/2001
• Issued: 10/06/2009
• Est. Priority Date: 10/30/2001
• Status: Expired due to Fees

• Current Assignee: Boston Scientific Scimed, Inc. (Boston Scientific Corporation)
• Original Assignee: Boston Scientific Scimed, Inc. (Boston Scientific Corporation)
• Inventors: Girton, Timothy S., Brodeur, Christopher B., Hill, Jason P., Sogard, David J.
• Primary Examiner(s): Aftergut; Jeff H
• Application Number:
  US10/012,919
• Publication Number:
  US 20030082324A1
• Time in Patent Office: 2,898 Days
• Field of Search: 156/293, 156/294, 156/244.13, 156/244.11, 623/1.13, 623/23.7, 623/23.71
• US Class Current: 156/294
• CPC Class Codes: A61F 2/07 Stent-grafts
• CPC Class Codes: A61F 2/90 characterised by a net-like or mesh-like structure
• CPC Class Codes: A61F 2002/072 Encapsulated stents, e.g. wire or whole stent embedded in lining
• CPC Class Codes: A61F 2002/075 the stent being loosely attached to the graft material, e.g. by stitching
• CPC Class Codes: A61F 2220/0075 sutured, ligatured or stitched, retained or tied with a rope, string, thread, wire or cable
• CPC Class Codes: A61L 27/16 obtained by reactions only involving carbon-to-carbon unsaturated bonds
• CPC Class Codes: A61L 31/048 obtained by reactions only involving carbon-to-carbon unsaturated bonds A61L31/041 takes precedence
• CPC Class Codes: B29C 2793/009 after shaping
• CPC Class Codes: B29C 2948/92647 Thickness
• CPC Class Codes: B29C 2948/92857 Extrusion unit
• CPC Class Codes: B29C 48/09 Articles with cross-sections having partially or fully enclosed cavities, e.g. pipes or channels
• CPC Class Codes: B29C 48/10 flexible, e.g. blown foils
• CPC Class Codes: B29C 48/25 Component parts, details or accessories; Auxiliary operations
• CPC Class Codes: B29C 48/32 with annular openings, e.g. for forming tubular articles
• CPC Class Codes: B29C 48/475 using pistons, accumulators or press rams
• CPC Class Codes: B29C 48/793 upstream of the plasticising zone, e.g. heating in the hopper
• CPC Class Codes: B29C 48/83 Heating or cooling the cylinders
• CPC Class Codes: B29C 48/832 Heating
• CPC Class Codes: B29C 48/865 Heating
• CPC Class Codes: B29C 48/902 internally
• CPC Class Codes: B29C 48/92 : Measuring, controlling or regulating
• CPC Class Codes: B29C 55/22 : of tubes B29C61/08 takes precedence
• CPC Class Codes: B29K 2027/18 : PTFE, i.e. polytetrafluorethene , e.g. ePTFE, i.e. expanded polytetrafluorethene
• CPC Class Codes: B29L 2009/00 : Layered products
• CPC Class Codes: B29L 2023/00 : Tubular articles B29L2024/00 takes precedence ; catheters B29L2031/7542
• CPC Class Codes: B29L 2031/7534 : Cardiovascular protheses
• CPC Class Codes: B29L 2031/7542 : Catheters
• CPC Class Codes: C08L 27/18 : Homopolymers or copolymers or tetrafluoroethene
• CPC Class Codes: Y10T 428/139 : Open-ended, self-supporting conduit, cylinder, or tube-type article

Abstract

The present invention is directed to a green fluoropolymer tube which has a wall thickness of about 250 microns or less, preferably about 200 microns or less, and more preferably about 125 microns or less. With such thinness, the green tube may be formed into a tube of expanded fluoropolymer having a wall thickness of about 250 microns or less, preferably about 200 μm or less and more preferably about 125 microns or less. Such an expanded fluoropolymer tube is particularly well-suited for use as an endovascular prosthesis, such as a graft, or in a stent-graft, because of its flexibility and strength.

Claims

1. A process for forming an implantable prosthesis, comprising the steps of:

extruding an extrudate consisting on a lubricant and PTFE to form a tubular member having a wall with an inner surface and an outer surface, a thickness being defined between said inner and outer surfaces in the range of about 250 μ

m or less at the exit of an extruder die used in the extruding, wherein said inner surface has a smooth inner surface having a single constant diameter;

wherein a pressurized stable medium is injected into a lumen of said tubular member during extrusion to provide support thereof; and

disposing a distensible member concentrically relative to said tubular member.

2. A process as in claim 1 further comprising:

at least partially expanding said tubular member.

3. A process as in claim 2 further comprising extruding a fluoropolymer to form a second tubular member having a second wall with a second inner surface and a second outer surface, a second thickness being defined between said second inner and second outer surfaces, said second thickness being in the range of about 250 μ

m or less;

at least partially expanding said second tubular member; and

disposing said second expanded tubular member concentrically relative to said expanded tubular member.

4. A process as in claim 3, wherein said distensible member is interposed between said expanded tubular member and said second expanded tubular member.

5. A process as in claim 4, wherein said distensible member includes interstices, said expanded tubular member being bonded to said second expanded tubular member through said interstices.

6. A process as in claim 5, wherein said distensible member is non-bondedly disposed between said expanded tubular member and said second expanded tubular member.

7. A process as in claim 3, wherein said fluoropolymer is PTFE.

8. A process as in claim 3, wherein said second tubular member is expanded through about 500 to about 6000% of elongation.

9. A process as in claim 2, wherein said distensible member is at least partially recessed within said expanded tubular member.

10. A process as in claim 1, wherein said thickness being in the range of about 200 μ

m or less at the exit of the extruder die used in the extruding.

11. A process as in claim 10, wherein said thickness being in the range of about 125 μ

m or less at the exit of the extruder die used in the extruding.

12. A process as claim 1, wherein said tubular member is hollow upon extrusion.

13. A process as in claim 1, wherein said distensible member is disposed in contiguous contact with said inner surface.

14. A process as in claim 1, wherein said distensible member is disposed in contiguous contact with said outer surface.

15. A process as in claim 2, wherein said tubular member is expanded through about 500 to about 6000% of elongation.

16. A process as in claim 1, wherein tension is applied to said tubular member during extruding.

17. A process as in claim 1, wherein said thickness varies by 5 μ

m or less throughout the length of said tubular member.

27. A process as in claim 1, wherein said inner surface has a substantially cylindrical cross-section.

18. A method of forming a stent-graft device comprising the steps of:

forming an expandable fluoropolymeric tube from an extruded green fluoropolymer tube having a wall thickness of about 250 μ

m or less, said green fluoropolymer tube having an inner surface, said inner surface having a smooth inner surface having a single constant diameter;

wherein a pressurized stable medium is injected into a lumen of said green fluoropolymer tube during extrusion of said green fluoropolymer tube to provide support thereof; and

dispensing a distensible member concentrically thereabout.

19. A method as in claim 18 further comprising:

dispensing a second expandable fluoropolymeric tube formed from an extruded green fluoropolymer tube having a wall thickness of about 250 μ

m or less about said distensible member.

20. A method as in claim 19, wherein said wall thickness of said second tube being about 200 μ

m or less.

21. A method as in claim 20, wherein said wall thickness of said second tube being about 125 μ

m or less.

22. A method as in claim 18 further including the step of joining together said tubes.

23. A method as in claim 22 wherein said joining includes the use of heat and pressure.

24. A method as in claim 22 wherein said joining includes the use of adhesive.

25. A method as in claim 18, wherein said wall thickness is about 200 μ

m or less.

26. A method as in claim 25, wherein said wall thickness is about 125 μ

m or less.

28. A method as in claim 18, wherein said inner surface has a substantially cylindrical cross-section.