Radially expandable polytetrafluoroethylene

• US 20040157024A1
• Filed: 02/05/2004
• Published: 08/12/2004
• Est. Priority Date: 06/27/1994
• Status: Active Grant

• Current Assignee: Bard Peripheral Vascular Incorporated (Becton, Dickinson & Co)
• Original Assignee: Bard Peripheral Vascular Incorporated (Becton, Dickinson & Co)
• Inventors: Colone, William M.
• Granted Patent: US 7,465,483 B2
• Time in Patent Office: Days
• US Class Current: 428/36.9
• CPC Class Codes: A61F 2/07 Stent-grafts
• CPC Class Codes: A61F 2/82 Devices providing patency to, or preventing collapsing of, tubular structures of the body, e.g. stents stent-grafts for tubular structures of the body other than blood vessels A61F2/04; stent-grafts for blood vessels A61F2/07; instruments specially adapted for placement or removal of stents or stent-grafts A61F2/95; for closing wounds, or holding wounds closed A61B17/04 - A61B17/115; dilators A61M29/00
• 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 2210/0019 operated at only one temperature whilst inside or touching the human body, e.g. constrained in a non-operative shape during surgery, another temperature only occurring before the operation
• CPC Class Codes: A61F 2220/005 using adhesives
• CPC Class Codes: A61F 2220/0058 soldered or brazed or welded
• CPC Class Codes: A61F 2250/0067 Means for introducing or releasing pharmaceutical products into the body
• CPC Class Codes: A61L 31/048 obtained by reactions only involving carbon-to-carbon unsaturated bonds A61L31/041 takes precedence
• CPC Class Codes: B29C 2791/001 Shaping in several steps
• CPC Class Codes: B29C 48/00 Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor extrusion blow-moulding B29C49/04
• CPC Class Codes: B29C 48/0012 combined with shaping by internal pressure generated in the material, e.g. foaming
• CPC Class Codes: B29C 48/0018 combined with shaping by orienting, stretching or shrinking, e.g. film blowing B29C48/0017 takes precedence
• CPC Class Codes: B29C 48/022 characterised by the choice of material
• 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 49/04 Extrusion blow-moulding
• CPC Class Codes: B29C 49/6472 in several stages
• CPC Class Codes: B29C 55/005 characterised by the choice of materials
• CPC Class Codes: B29C 55/24 radial
• CPC Class Codes: B29C 55/26 biaxial
• CPC Class Codes: B29C 67/04 : Sintering combined with compression B29C43/00
• CPC Class Codes: B29K 2027/18 : PTFE, i.e. polytetrafluorethene , e.g. ePTFE, i.e. expanded polytetrafluorethene
• CPC Class Codes: B29K 2105/04 : cellular or porous
• CPC Class Codes: B29L 2023/005 : Hoses, i.e. flexible
• CPC Class Codes: B29L 2031/753 : Medical equipment; Accessories therefor bloodbags, medical bags B29L2031/7148; artificial eyes B29L2011/0008
• CPC Class Codes: B29L 2031/7542 : Catheters
• CPC Class Codes: C08L 27/18 : Homopolymers or copolymers or tetrafluoroethene
• CPC Class Codes: Y10S 623/901 : Method of manufacturing prosthetic device
• CPC Class Codes: Y10T 428/13 : Hollow or container type article [e.g., tube, vase, etc.]
• CPC Class Codes: Y10T 428/1328 : Shrinkable or shrunk [e.g., due to heat, solvent, volatile agent, restraint removal, etc.]
• CPC Class Codes: Y10T 428/1334 : Nonself-supporting tubular film or bag [e.g., pouch, envelope, packet, etc.]
• CPC Class Codes: Y10T 428/1352 : Polymer or resin containing [i.e., natural or synthetic]
• CPC Class Codes: Y10T 428/1376 : Foam or porous material containing
• CPC Class Codes: Y10T 428/139 : Open-ended, self-supporting conduit, cylinder, or tube-type article

Abstract

Extruded, stretched, sintered tubular PTFE materials are produced which are suited for use in the medical field as liners and covers for expandable stents. The PTFE materials have an unusually low REC (Radial Expansion Coefficient) and RER (Radial Expansion Ratio).

Claims

1. A method for producing a porous tube consisting essentially of highly crystalline polytetrafluoroethylene polymer, comprising the steps of

(a) extruding a lubricant—

polytetrafluoroethylene resin blend to form a tubing having a longitudinal axis, a primary inner diameter, and a primary length;

(b) heating the tubing to remove the lubricant;

(c) stretching the tubing along said longitudinal axis to produce an elongated tubing having a secondary length greater than said primary length;

(d) restraining said elongate tubing to prevent said elongate tubing from longitudinally contracting during sintering;

(e) sintering said elongated tubing to produce a sintered tubing having a length substantially equivalent to said secondary length;

(f) radially expanding said sintered tubing to produce radially expanded tubing have an expanded inner diameter greater than said primary inner diameter; and

,

(g) sintering said radially expanded tubing to contract said radially expanded tubing and produce a tubing having an inner diameter substantially equivalent to said primary inner diameter.

2. The method of claim 1 including the additional step after step (g) of longitudinally stretching said sintered radially expanded tubing.

3. The method of claim 1 including the step intermediate steps (f) and (g) of restraining the ends of said radially expanded tubing to maintain the length of said radially expanded tubing when said radially expanded tubing is sintered.

4. A porous material consisting essentially of highly crystalline polytetrafluoroethylene polymer, which material has a microstructure characterized by nodes interconnected by fibrils and has been radially pre-dilated.

5. A porous material in accordance with claim 4 which is in the form of a shaped article.

6. A porous material in accordance with claim 5 which is in the form of a tube having an inner diameter.

7. A porous material in accordance with claim 6 in which said tube is radially pre-dilated to at least two times said inner diameter.

8. A porous material in accordance with claim 6 in which said tube is radially pre-dilated to at least three times said inner diameter.

9. A porous material in accordance with claim 6 in which said tube is radially pre-dilated to at least four times said inner diameter.

10. A porous material in accordance with claim 6 in which said tube is radially pre-dilated to at least five time said inner diameter.

11. A porous material consisting essentially of highly crystalline polytetrafluoroethylene polymer, which material has a microstructure characterized by nodes interconnected by fibrils;

has a Radial Expansion Coefficient (REC) of less than 2.0; and

has been radially pre-dilated.

20. A porous material in accordance with claim 11 which is in the form of a shaped article.

21. A porous material in accordance with claim 20 which is in the form of a tube.

12. A porous material consisting essentially of highly crystalline polytetrafluoroethylene polymer, which material has a microstructure characterized by nodes interconnected by fibrils;

has a Radial Expansion Coefficient (REC) of less than 1.7; and

has been radially pre-dilated.

22. A porous material in accordance with claim 12 which is in the form of a shaped article.

23. A porous material in accordance with claim 22 which is in the form of a tube.

13. A porous material consisting essentially of highly crystalline polytetrafluoroethylene polymer, which material has a microstructure characterized by nodes interconnected by fibrils;

has a Radial Expansion Coefficient (REC) of less than 1.5; and

has been radially pre-dilated.

24. A porous material in accordance with claim 13 which is in the form of a shaped article.

25. A porous material in accordance with claim 24 which is in the form of a tube.

14. A porous material consisting essentially of highly crystalline polytetrafluoroethylene polymer, which material has a microstructure characterized by nodes interconnected by fibrils;

has a Radial Expansion Coefficient (REC) of less than 1.0; and

, has been radially pre-dilated.

26. A porous material in accordance with claim 14 which is in the form of a shaped article.

27. A porous material in accordance with claim 26 which is in the form of a tube.

15. A porous material consisting essentially of highly crystalline polytetrafluoroethylene polymer, which material has a microstructure characterized by nodes interconnected by fibrils;

has a Radial Expansion Ratio (RER) of less than 30; and

, has been radially pre-dilated.

28. A porous material in accordance with claim 15 which is in the form of a shaped article.

29. A porous material in accordance with claim 28 which is in the form of a tube.

16. A porous material consisting essentially of highly crystalline polytetrafluoroethylene polymer, which material has a microstructure characterized by nodes interconnected by fibrils;

has a Radial Expansion Ratio (RER) of less than 20; and

, has been radially pre-dilated.

30. A porous material in accordance with claim 16 which is in the form of a shaped article.

31. A porous material in accordance with claim 30 which is in the form of a tube.

17. A porous material consisting essentially of highly crystalline polytetrafluoroethylene polymer, which material has a microstructure characterized by nodes interconnected by fibrils;

has a Radial Expansion Ratio (RER) of less than 10; and

, has been radially pre-dilated.

32. A porous material in accordance with claim 17 which is in the form of a shaped article.

33. A porous material in accordance with claim 32 which is in the form of a tube.

18. A porous material consisting essentially of highly crystalline polytetrafluoroethylene polymer, which material has a microstructure characterized by nodes interconnected by fibrils;

has a Radial Expansion Ratio (RER) of less than 5; and

, has been radially pre-dilated.

34. A porous material in accordance with claim 18 which is in the form of a shaped article.

35. A porous material in accordance with claim 34 which is in the form of a tube.

19. A porous material consisting essentially of highly crystalline polytetrafluoroethylene polymer, which material has a microstructure characterized by nodes interconnected by fibrils;

has a ratio of Reduction Ration (RR) to Lubricant Level (LL) of less than 5; and

, has been radially pre-dilated.

36. A porous material in accordance with claim 19 which is in the form of a shaped article.

37. A porous material in accordance with claim 36 which is in the form of a tube.

38. A porous material consisting essentially of highly crystalline polytetrafluoroethylene polymer, which material has a microstructure characterized by nodes interconnected by fibrils;

has a structural integrity which is retained until said material is radially expanded by more than 50%; and

has been radially pre-dilated.

39. A porous material consisting essentially of highly crystalline polytetrafluoroethylene polymer, which material has a microstructure characterized by nodes interconnected by fibrils;

has a structural integrity which is retained until said material is radially expanded by more than 75%; and

, has been radially pre-dilated.

40. A porous material consisting essentially of highly crystalline polytetrafluoroethylene polymer, which material has a microstructure characterized by nodes interconnected by fibrils;

has a structural integrity which is retained until said material is radially expanded by more than 100%; and

, has been radially pre-dilated.

41. A porous material consisting essentially of highly crystalline polytetrafluoroethylene polymer, which material has a microstructure characterized by nodes interconnected by fibrils;

has a structural integrity which is retained until said material is radially expanded by more than 150%; and

has been radially pre-dilated.