Method of producing a tube for use in the formation of a stent, and such tube

• US 10,299,944 B2
• Filed: 09/24/2013
• Issued: 05/28/2019
• Est. Priority Date: 09/24/2012
• Status: Active Grant

• Current Assignee: Arterius Limited
• Original Assignee: Arterius Limited
• Inventors: Al-Lamee, Kadem, Kelly, Adrian, Coates, Philip D., Thompson, Glen P., Caton-Rose, Phil
• Primary Examiner(s): Wollschlager, Jeffrey M
• Application Number:
  US14/430,497
• Publication Number:
  US 20150230946A1
• Time in Patent Office: 2,072 Days
• CPC Class Codes: A61F 2/04 Hollow or tubular parts of organs, e.g. bladders, tracheae, bronchi or bile ducts A61F2/18, A61F2/20 take precedence; devices, other than stent-grafts, providing patency to, or preventing collapsing of, tubular structures of the body other than stent-grafts, e.g. stents A61F2/82; instruments specially adapted for placement or removal of stents or stent-grafts A61F2/95
• 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 2210/0004 bioabsorbable
• 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 48/152 the inner surfaces thereof
• CPC Class Codes: B29C 55/22 of tubes B29C61/08 takes precedence
• CPC Class Codes: B29C 55/24 radial
• CPC Class Codes: B29C 55/26 biaxial
• CPC Class Codes: B29C 55/30 Drawing through a die pultrusion B29C70/52
• CPC Class Codes: B29C 70/52 Pultrusion, i.e. forming and compressing by continuously pulling through a die
• CPC Class Codes: B29D 23/00 Producing tubular articles B29D24/00 takes precedence
• CPC Class Codes: B29K 2995/006 Bio-degradable, e.g. bioabsorbable, bioresorbable or bioerodible
• CPC Class Codes: B29L 2023/007 Medical tubes other than catheters catheters B29L2031/7542

Abstract

Bioresorbable polymeric tubes suitable for use in a stent have been produced by a using a die drawing technique, comprising: —deforming an orientable, thermoplastic polymer tubing (4) in the solid phase by drawing it over a mandrel (1) and/or through a die (3), where the mandrel (1) has a lead end and an exit end and the die (3) has an entry side and an exit side, wherein a drawing mechanism applies a drawing tension to the tubing (4) from the exit end of the mandrel (1) and/or the exit side of the die (3), said tension being insufficient to cause tensile failure of the tubing but sufficient to deform the tubing, thereby drawing the tubing over the mandrel (1) and/or through the die (3) in the solid phase to induce uniaxial or biaxial orientation of the polymer; and —collecting the deformed tubing from the exit end of the mandrel (1) and/or the exit side of the die (3).

Claims

1. A method of producing a tube for use in the formation of a stent, said method comprising:

deforming an orientable, thermoplastic polymer tubing in the solid phase by drawing it over a mandrel, where the mandrel has a lead end and an exit end, and through a die, where the die has an entry side and an exit side wherein;

a drawing mechanism applies a drawing tension to the tubing from the exit end of the mandrel and the exit side of the die, said tension being insufficient to cause tensile failure of the tubing but sufficient to deform the tubing, thereby drawing the tubing over the mandrel and through the die in the solid phase to induce uniaxial or biaxial orientation of the polymer; and

collecting the deformed tubing from the exit end of the mandrel and exit side of the die;

wherein the orientable, thermoplastic polymer tubing has an inner diameter from 0.5 mm to 4.0 mm, and an outer diameter from 0.9 mm to 15 mm;

the diameter of the mandrel at its widest point is from 0.01 to 15 mm;

the wall thickness of the deformed tubing is from 75 to 300 microns; and

wherein the die is a diverging die or a parallel die.

2. The method according to claim 1, wherein the orientable, thermoplastic polymer tubing is heated to a temperature above the glass transition temperature and below the melting temperature of the thermoplastic polymer.

3. The method according to claim 1, wherein the bulk cross-sectional area of the polymeric tubing is reduced by drawing said tubing over the mandrel.

4. The method according to claim 1, wherein the mandrel is an expanding cone mandrel.

5. The method according to claim 4, wherein the expanding cone mandrel has a taper with an angle of inclination of the taper from 5 to 60 degrees.

6. The method according to claim 1, wherein the entry side of the die has a diameter from 0.4 to 8.00 mm or the exit side of the die has a diameter from 1.0 to 15 mm or both.

7. The method according to claim 1, wherein the die has a semi angle of the die entry or a semi angle of the die exit or both semi angles of the die entry and of the die exit have the semi angle from 0 to 50 degrees.

8. The method according to claim 1, wherein the ratio of the die entry or exit angle and an angle of inclination of the mandrel taper is in the range of 1:

1 to 10;

1.

9. The method according to claim 1, wherein an inner hoop draw ratio is at least 1.5 or wherein an axial draw ratio is from 1.5:

1 to 15;

1 or both.

10. The method according to claim 1, wherein a ratio of an axial draw ratio to an inner hoop draw ratio is in the range of 0.5:

1 to 10;

1.

11. The method according to claim 1, further comprising the step of extruding the thermoplastic polymeric tubing from an upstream extruder prior to the deformation step.

12. The method according to claim 1, wherein a cooling of the orientable, thermoplastic polymer tubing starts while in contact with the die and/or mandrel or immediately after said tubing has been drawn over the mandrel and/or through the die.

13. The method according to claim 1, wherein the orientable, thermoplastic polymer tubing for use in said method has a wall thickness of 0.1 mm to 1.0 mm.

14. The method according to claim 1 further comprising preparing a stent from the deformed tubing.

15. The method according to claim 4, wherein the expanding cone mandrel has a taper with an angle of inclination of the taper from 20 to 40 degrees.

16. The method according to claim 1, wherein the entry side of the die has a diameter from 2.0 to 4.0 mm.

17. The method according to claim 1, wherein the die is a diverging die.

18. The method according to claim 1, wherein a semi angle of the die entry and/or die exit is from 20 to 40 degrees.

19. The method according to claim 1, wherein a ratio of the die entry or exit angle and an angle of inclination of a mandrel taper is in the range of 1:

1 to 5;

1.

20. The method according to claim 1, wherein an axial draw ratio is from 2.5:

1 and 4;

1.

21. The method according to claim 1, wherein the wall thickness of the deformed tubing is from 75 to 150 microns.