Rapidly recoverable PTFE and process therefore

• US 4,877,661 A
• Filed: 10/19/1987
• Issued: 10/31/1989
• Est. Priority Date: 10/19/1987
• Status: Expired due to Term

• Current Assignee: W. L. Gore & Associates (W.L. Gore & Associates)
• Original Assignee: W. L. Gore & Associates (W.L. Gore & Associates)
• Inventors: House, Wayne D., Myers, David J.
• Primary Examiner(s): Robinson, Ellis P.
• Assistant Examiner(s): Seidleck, James J.
• Application Number:
  US07/110,145
• Time in Patent Office: 743 Days
• Field of Search: 428/36, 428/422, 428/398, 428/910, 428/34.9, 428/174, 428/364, 264/255.8, 264/289.6, 264/DIG. 73
• US Class Current: 428/34.9
• CPC Class Codes: B29C 55/005 characterised by the choice of materials
• CPC Class Codes: B29C 67/20 for porous or cellular articles, e.g. of foam plastics, coarse-pored chemical aspects of working up macro-molecular substances to porous or cellular articles C08J9/00
• 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: C08J 2327/18 Homopolymers or copolymers of tetrafluoroethylene
• CPC Class Codes: C08J 5/18 Manufacture of films or sheets
• CPC Class Codes: Y10S 264/73 Processes of stretching
• CPC Class Codes: Y10S 428/91 Product with molecular orientation
• CPC Class Codes: Y10T 428/1328 Shrinkable or shrunk [e.g., due to heat, solvent, volatile agent, restraint removal, etc.]
• CPC Class Codes: Y10T 428/24628 Nonplanar uniform thickness material
• CPC Class Codes: Y10T 428/2913 Rod, strand, filament or fiber
• CPC Class Codes: Y10T 428/2975 Tubular or cellular
• CPC Class Codes: Y10T 428/31544 Addition polymer is perhalogenated

Abstract

This invention relates to porous polytetrafluoroethylene (hereinafter PTFE) materials having the property of rapid recovery and a method for producing these materials. The microstructure of the porous PTFE material consists of nodes interconnected by fibrils, substantially all of the fibrils having a bent or wavy appearance. Artricles made from these materials are particularly suitable for use in the medical field, but are also useful in other areas such as filtration and fabric applications.

Claims

1. A porous shaped article consisting essentially of PTFE, said article having a microstructure of nodes interconnected by fibrils, said article at ambient temperature capable of being stretched and then rapidly recovering more than about 6% of its stretched length.

2. The article of claim 1 in which said article at ambient temperature is capable of being stretched and then rapidly recovering more than about 8%.

3. The article of claim 1 in which said article at ambient temperature is capable of being stretched and then rapidly recovering more than about 10%.

4. The article of claim 1 in which said article at ambient temperature is capable of being stretched and then rapidly recovering more than about 15%.

5. The article of claim 1 in which said article at ambient temperature is capable of being stretched and then rapidly recovering more than about 20%.

6. The article of claim 1 in which said article at ambient temperature is capable of being stretched and then rapidly recovering more than about 22%.

7. The article of claim 1 in which said article at ambient temperature is capable of being stretched and then rapidly recovering more than about 25%.

8. The article of claim 1 in which said article at ambient temperature is capable of being stretched and then rapidly recovering more than about 30%.

9. The article of claim 1 in which said article at ambient temperature is capable of being stretched and then rapidly recovering more than about 50%.

20. An article according to any of the above claims in the shape of a tube having smooth inside and outside surfaces.

21. An article according to claim 20 in which the inside surface and the outside surface differ.

22. An article according to claim 1 which has been formed as a tube and subsequently slit longitudinally and opened to form a sheet.

23. An article according to claim 1 in the form of a sheet.

24. An article according to claim 1 in the form of a rod.

25. An article according to claim 1 in the form of a film.

26. An article according to claim 1 in the form of a filament.

27. An article claimed in claim 1 that has corrugated surfaces.

10. A porous article consisting essentially of PTFE, said article having a microstructure of nodes interconnected by fibrils, substantially all of said fibrils having a bent appearance, said article at ambient temperature is capable of being stretched and then rapidly recovering more than 5.5% of its stretched length.

11. The article of claim 10 in which said article at ambient temperature is capable of being stretched and then rapidly recovering more than 6% of its stretched length.

12. The article of claim 10 in which said article at ambient temperature is capable of being stretched and then rapidly recovering more than 8% of its stretched length.

13. The article of claim 10 in which said article at ambient temperature is capable of being stretched and then rapidly recovering more than 10% of its stretched length.

14. The article of claim 10 in which said article at ambient temperature is capable of being stretched and then rapidly recovering more than 15% of its stretched length.

15. The article of claim 10 in which said article at ambient temperature is capable of being stretched and then rapidly recovering more than 20% of its stretched length.

16. The article of claim 10 in which said article at ambient temperature is capable of being stretched and then rapidly recovering more than 22% of its stretched length.

17. The article of claim 10 in which said article at ambient temperature is capable of being stretched and then rapidly recovering more than 25% of its stretched length.

18. The article of claim 10 in which said article at ambient temperature is capable of being stretched and then rapidly recovering more than 30% of its stretched length.

19. The article of claim 10 in which said article at ambient temperature is capable of being stretched and then rapidly recovering more than 50% of its stretched length.

28. An extruded, expanded article heat treated above its crystalline melt point, made of a material consisting essentially of porous polytetrafluoroethylene (PTFE) having been subsequently compressed at least 50% in the direction in which rapid recoverable characteristics are desired, restrained and heated.

29. An extruded, expanded and heat treated above its crystalline melt point article as claimed in claim 28 wherein the material was subsequently compressed at least 60% in the direction of desired rapid recoverable characteristics.

30. An extruded, expanded and heat treated above its crystalline melt point article as claimed in claim 28 wherein the material was compressed at least 75% in the direction of desired rapid recoverable characteristics.

31. An extruded, expanded and heat treated above its crystalline melt point article as claimed in claim 28 wherein the material was compressed at least 90% in the direction of desired rapid recoverable characteristics.

32. An article as claimed in claim 28 having a rapid recovery greater than about 5.5%.

33. An article as claimed in claim 28 having a rapid recovery greater than about 10%.

34. An article as claimed in claim 28 having a rapid recovery greater than about 20%.

35. An article as claimed in claim 28 having a rapid recovery greater than about 25%.

36. An article as claimed in claim 28 having a rapid recovery greater than about 30%.

37. An article as claimed in claim 28 having a rapid recovery greater than about 50%.

38. An article as claimed in claim 28 having a rapid recovery greater than about 75%.

39. An article as claimed in claim 28 that is in the shape of a tube having smooth inside and outside surfaces.

40. An article as claimed in claim 28 that is in the shape of a tube in which the inside surface and the outside surface differ.

41. An article as claimed in claim 28 which has been formed as a tube and subsequently slit longitudinally and opened to form a sheet.

42. An article as claimed in claim 28 that is in the shape of a sheet made other than by slitting tubes.

43. An article claimed in claim 28 that is in the shape of a rod.

44. An article claimed in claim 28 that is in the shape of a film.

45. A porous shaped article consisting essentially of PTFE, said article having a microstructure of nodes and fibrils made by the following steps comprising:

(a) compressing said article to less than 50% of its original length and restraining it;

(b) heating said article at an elevated temperature for a period of time;

(c) cooling said article; and

(d) stretching said article to approximately its original length.

46. A porous PTFE article of claim 45 in which said article at ambient temperature has a rapid recovery greater than about 6%.

47. A porous PTFE article of claim 45 in which said article at ambient temperature has a rapid recovery greater than about 8%.

48. A porous PTFE article of claim 45 in which said article at ambient temperature has a rapid recovery greater than about 10%.

49. A porous PTFE article of claim 45 in which said article at ambient temperature has a rapid recovery greater than about 15%.

50. A porous PTFE article of claim 45 in which said article at ambient temperature has a rapid recovery greater than about 20%.

51. A porous PTFE article of claim 45 in which said article at ambient temperature has a rapid recovery greater than about 22%.

52. A porous PTFE article of claim 45 in which said article at ambient temperature has a rapid recovery greater than about 25%.

53. A porous PTFE article of claim 45 in which said article at ambient temperature has a rapid recovery greater than about 30%.