Radially expandable polytetrafluoroethylene

• US 8,158,041 B2
• Filed: 12/28/2007
• Issued: 04/17/2012
• Est. Priority Date: 06/27/1994
• Status: Expired due to Fees

• Current Assignee: Bard Peripheral Vascular Incorporated (Becton, Dickinson & Co)
• Original Assignee: Bard Peripheral Vascular Incorporated (Becton, Dickinson & Co)
• Inventors: Colone, William M.
• Primary Examiner(s): Crispino, Richard
• Assistant Examiner(s): Royston, Elizabeth
• Application Number:
  US11/966,444
• Publication Number:
  US 20080143011A1
• Time in Patent Office: 1,572 Days
• Field of Search: 264/119, 264/127, 264/209.5, 264/211, 264/230, 623/1.1, 623/1.43, 623/1.54, 623/1.49, 623/901, 521/919, 428/36.5, 428/36.9
• US Class Current: 264/127
• 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 of making a liner for an expandable stent, comprising:

extruding a polytetrafluoroethylene tube having a first length;

stretching the extruded tube to a second length greater than the first length;

sintering the stretched tube while restrained from longitudinal contraction;

dilating the sintered stretched tube from a first diameter to a second diameter larger than the first diameter; and

sintering the dilated tube while unrestrained to permit radial and longitudinal contraction, the contracted tube having a radial expansion ratio of about 1.0.

2. The method according to claim 1, wherein the stretching step includes stretching the extruded tube to a second length approximately four times greater than the first length.

3. The method according to claim 2, wherein the dilating step includes dilating the sintered stretched tube to a second diameter approximately five times greater than the first diameter.

4. The method according to claim 1, further comprising longitudinally stretching the tube following the second sintering step to a length greater than the first length.

5. The method according to claim 4, wherein the longitudinally stretching step following the second sintering step includes stretching the tube to a length approximately two times greater than the first length.

6. The method according to claim 4, wherein the longitudinally stretching step following the second sintering step includes stretching the tube to a length less than two times the first length.

7. The method according to claim 1, wherein the dilating step further comprises restraining the tube from longitudinal contraction.

8. The method according to claim 7, wherein the dilating step includes dilating the sintered stretched tube to a second diameter approximately five times greater than the first diameter.

9. A method of making an endoluminal device, comprising:

providing an expandable stent;

forming a liner, comprising;

extruding a polytetrafluoroethylene tube having a first length;

stretching the extruded tube to a second length greater than the first length;

sintering the stretched tube while restrained from longitudinal contraction;

dilating the sintered stretched tube from a first diameter to a second diameter larger than the first diameter;

sintering the dilated tube while unrestrained to permit radial and longitudinal contraction, the contracted tube having a radial expansion ratio of about 1.0; and

stretching the tube following the second sintering step to a length greater than the first length; and

associating the liner with the stent.

10. The method according to claim 9, wherein the first stretching step includes stretching the extruded tube to a second length approximately four times greater than the first length.

11. The method according to claim 10, wherein the dilating step includes dilating the sintered stretched tube to a second diameter approximately five times greater than the first diameter.

12. The method according to claim 9, wherein the second stretching step includes stretching the tube to a length approximately two times greater than the first length.

13. The method according to claim 9, wherein the second stretching step includes stretching the tube to a length less than two times the first length.

14. The method according to claim 9, wherein the dilating step further comprises restraining the tube from longitudinal contraction.

15. The method according to claim 14, wherein the dilating step includes dilating the sintered stretched tube to a second diameter approximately five times greater than the first diameter.

16. A method of making a polytetrafluoroethylene product, comprising:

extruding a polytetrafluoroethylene tube having a first length;

stretching the extruded tube to a second length greater than the first length;

sintering the stretched tube while restrained from longitudinal contraction;

dilating the sintered stretched tube from a first diameter to a second diameter larger than the first diameter;

sintering the dilated tube while unrestrained to substantially contract the tube to the first length and the first diameter, the contracted tube having a radial expansion ratio of about 1.0; and

stretching the contracted tube to a third length greater than the first length.

17. The method according to claim 16, wherein the third length is approximately two times greater than the first length.

18. The method according to claim 16, wherein the third length is less than two times the first length.

19. The method according to claim 16, wherein the second length is approximately four times greater than the first length.

20. The method according to claim 16, wherein the second diameter is approximately five times greater than the first diameter.