Method for forming hollow fibers

Abstract

A thin walled microtube is formed by providing a continuous elongated member having an outer surface. The member is at least partially formed of a water soluble material. A coating material is provided. The coating material may be a silicone compound that is curable such that the coating material cures into a substantial non-porous silicone. The outer surface of the elongated member is coated with a coating material so as to form a substantially uniform and continuous layer of coating material on the outer surface. The layer of coating material is cured so as to form a substantial uniform and continuous layer of substantially non-porous silicone on the outer surface. The elongated member is at least partially dissolved using water and purged from the silicone layer, such that an elongated tube of substantially non-porous silicone is formed.

1. A method for forming a thin walled microtube, comprising the steps of:
 providing a continuous elongated member having an outer surface, the member being at least partially formed of a water soluble material, the continuous elongated member being a continuous thin walled tube;  
 providing a coating material, the coating material comprising a silicone compound, the compound being curable such that the coating material cures into a substantially non-porous silicone;  
 coating the outer surface of the elongated member with the coating material in a substantially continuous process so as to form a substantially uniform and continuous layer of coating material on the outer surface;  
 curing the layer of coating material so as to form a substantially uniform and continuous layer of substantially non-porous silicone on the outer surface;  
 at least partially dissolving the elongated member using water; and  
 purging the at least partially dissolved member from the silicone layer;  
 whereby an elongated microtube of substantially non-porous silicone is formed.  
 
     
     
       2. The method according to  claim 1 , wherein the continuous elongated member comprises a continuous thin walled tube. 
     
     
       3. The method according to claim  2    1 , wherein the tube has a diameter in the range of 50 to 400 microns and a wall thickness in the range of 5 to 100 microns. 
     
     
       4. The method according to  claim 3 , wherein the cured layer of silicone has a thickness in the range of 5 to 100 microns. 
     
     
       5. The method according to claim  2    1 , wherein the tube has a central passage therethrough and the dissolving step comprises passing hot water through the central passage. 
     
     
       6. The method according to  claim 1 , wherein the dissolving step comprises exposing the coated member to steam. 
     
     
       7. The method according to  claim 1 , wherein the elongated member has a central axis, the outer surface of the elongated member being cylindrical such that all portions of the outer surface are equidistant from the central axis. 
     
     
       8. The method according to  claim 1 , wherein the continuous elongated member is substantially completely formed from water-soluble polyvinyl alcohol. 
     
     
       9. The method according to  claim 1 , wherein the curing step comprises passing the coated elongated member through a heating device to heat cure the coating material. 
     
     
       10. The method according to  claim 1 , wherein the coating material is a first coating material, the method further comprising the step of coating the continuous elongated member with a second coating material prior to coating the continuous elongated member with the first material. 
     
     
       11. The method according to  claim 1 , wherein the coating material is a first coating material, the method further comprising the step of coating the continuous elongated member with a second coating material after coating the continuous elongated member with the first material. 
     
     
       12. The method according to  claim 1 , further comprising recoating the continuous elongated member with the coating material so as to form a second substantially uniform and continuous layer of coating material on the outer surface. 
     
     
       13. The method according to  claim 1 , wherein the coating step comprises providing a coating die and continuously passing the elongated member therethrough. 
     
     
       14. The method according to  claim 1 , further comprising:
 collecting a plurality of the coated elongated members after the curing step and prior to the dissolving step;  
 grouping the collection of coated members into a bundle having a first end and a second end with a bundle body therebetween;  
 potting the first end of the bundle with a potting material so as to form a first potted end;  
 potting the second end of the bundle with a potting material so as to form a second potted end; and  
 cutting through the first and second potted ends such that the coated elongated members are cut and the elongated members are at least partially exposed.  
 
     
     
       15. A method for forming a thin walled microtube, comprising the steps of:
 forming a continuous elongated member from a water soluble polyvinyl alcohol, the elongated member having a central axis and a cylindrical outer surface, the outer surface being uninterrupted with all portions of the outer surface being substantially equidistant from the central axis;  
 providing a coating material, the coating material comprising a silicone compound, the compound being curable such that the coating material cures into a substantially non-porous silicone;  
 providing a coating die having an orifice and a coating reservoir;  
 filling the coating reservoir with the coating material and continuously passing the elongated material through the orifice and the coating reservoir such that a substantially uniform layer of coating material is deposited on the outer surface of the elongated member, the layer forming an outer tube encasing the elongated member;  
 providing a curing device;  
 continuously passing the coated member through the curing device so as to cure the layer and form a substantially uniform and continuous tube of substantially non-porous silicone encasing the member;  
 exposing the elongated member to water so as to at least partially dissolve the elongated member; and  
 purging the at least partially dissolved member from the outer tube;  
 whereby an elongated microtube of substantially non-porous silicone is formed.  
 
     
     
       16. The method according to  claim 15 , wherein the continuous elongated member comprises a continuous thin walled tube. 
     
     
       17. The method according to  claim 16 , wherein the tube has a diameter in the range of 50 to 400 microns and a wall thickness in the range of 5 to 100 microns. 
     
     
       18. The method according to  claim 17 , wherein the cured layer of silicone has a thickness in the range of 5 to 100 microns. 
     
     
       19. The method according to  claim 16 , wherein the tube has a central passage therethrough and the dissolving step comprises passing hot water through the central passage. 
     
     
       20. The method according to  claim 15 , wherein the dissolving step comprises exposing the coated member to steam. 
     
     
       21. The method according to  claim 15 , wherein the curing device comprises a heater. 
     
     
       22. The method according to  claim 15 , wherein the coating material is a first coating material, the method further comprising the step of coating the continuous elongated member with a second coating material prior to coating the continuous elongated member with the first material. 
     
     
       23. The method according to  claim 15 , wherein the coating material is a first coating material, the method further comprising the step of coating the continuous elongated member with a second coating material after coating the continuous elongated member with the first material. 
     
     
       24. The method according to  claim 15 , further comprising recoating the continuous elongated member with the coating material so as to form a second substantially uniform and continuous layer of coating material on the outer surface. 
     
     
       25. A method of forming a portion of a gas exchange device having a plurality of thin walled microtubes, comprising the steps of:
 forming a plurality of coated members, each coated member being formed by the steps of: 
 providing a continuous elongated member having an outer surface, the member being at least partially formed of a water soluble material;  
 providing a coating material, the coating material comprising a silicone compound, the compound being curable such that the coating material cures into a substantially nonporous silicone;  
 coating the outer surface of the elongated member with the coating material in a substantially continuous process so as to form a substantially uniform and continuous layer of coating material on the outer surface;  
 curing the layer of coating material so as to form a substantially uniform and continuous layer of substantially non-porous silicone on the outer surface;  
 
 grouping the plurality of coated members into a bundle having a first end and a second end with a bundle body extending therebetween;  
 potting the first end of the bundle with a potting material so as to form a first potted end interconnecting and sealing the coated members to each other;  
 potting the second end of the bundle with a potting material so as to form a second potted end interconnecting and sealing the coated members to each other;  
 cutting off a portion of each of the first and second potted ends such that the coated members are cut and the elongated members are at least partially exposed;  
 at least partially dissolving the elongated members using water; and  
 purging the at least partially dissolved members from the silicone layers.  
 
     
     
       26. The method according to  claim 25 , wherein the continuous elongated members comprise a continuous thin walled tubes. 
     
     
       27. The method according to  claim 26 , wherein the tubes have a diameter in the range of 50 to 400 microns and a wall thickness in the range of 5 to 100 microns. 
     
     
       28. The method according to  claim 27 , wherein the cured layer of silicone on each of the members has a thickness in the range of 5 to 100 microns. 
     
     
       29. The method according to  claim 26 , wherein the tubes have a central passage therethrough and the dissolving step comprises passing hot water through the central passages. 
     
     
       30. The method according to  claim 25 , wherein the dissolving step comprises exposing the coated members to steam. 
     
     
       31. The method according to  claim 25 , wherein the elongated members each have a central axis, the outer surface of the elongated members each being cylindrical such that all portions of the outer surface are equidistant from the central axis. 
     
     
       32. The method according to  claim 25 , wherein the continuous elongated members are substantially completely formed from water soluble polyvinyl alcohol. 
     
     
       33. The method according to  claim 25 , wherein the curing step comprises passing each of the coated elongated members through a heating device to heat cure the coating material. 
     
     
       34. The method according to  claim 25 , wherein the coating material is a first coating material, the method further comprising the step of coating the continuous elongated member with a second coating material prior to coating the continuous elongated member with the first material. 
     
     
       35. The method according to  claim 25 , wherein the coating material is a first coating material, the method further comprising the step of coating the continuous elongated member with a second coating material after coating the continuous elongated member with the first material. 
     
     
       36. The method according to  claim 25 , further comprising recoating the continuous elongated member with the coating material so as to form a second substantially uniform and continuous layer of coating material on the outer surface. 
     
     
       37. The method according to  claim 25 , wherein the coating step comprises providing a coating die and continuously passing the elongated members therethrough. 
     
     
       38. A method for forming a thin walled microtube, comprising the steps of:
 providing a continuous elongated member having an outer surface, the member being at least partially formed of a water soluble material, the continuous elongated member being a continuous thin walled tube;  
 providing a coating material, the coating material being curable such that the material becomes a solid;  
 coating the outer surface of the elongated member with the coating material in a substantially continuous process so as to form a substantially uniform and continuous layer of coating material on the outer surface;  
 curing the layer of coating material so as to form a substantially uniform and continuous solid layer on the outer surface;  
 at least partially dissolving the elongated member using water; and  
 purging the at least partially dissolved member from the solid layer;  
 whereby an elongated tube of solid material is formed.  
 
     
     
       39. The method according to  claim 38 , wherein the coating material comprises a silicone compound, the compound being curable such that the coating material cures into a substantially non-porous silicone. 
     
     
       40. The method according to  claim 38 , wherein the continuous elongated member comprises a continuous thin walled tube. 
     
     
       41. The method according to claim  40    38 , wherein the tube has a diameter in the range of 50 to 400 microns and a wall thickness in the range of 5 to 100 microns. 
     
     
       42. The method according to claim  41    39 , wherein the cured layer of silicone has a thickness in the range of 5 to 100 microns. 
     
     
       43. The method according to claim  40    38 , wherein the tube has a central passage therethrough and the dissolving step comprises passing hot water through the central passage. 
     
     
       44. The method according to  claim 38 , wherein the dissolving step comprises exposing the coated member to steam. 
     
     
       45. The method according to  claim 38 , wherein the elongated member has a central axis, the outer surface of the elongated member being cylindrical such that all portions of the outer surface are equidistant from the central axis. 
     
     
       46. The method according to  claim 38 , wherein the continuous elongated member is substantially completely formed from water soluble polyvinyl alcohol. 
     
     
       47. The method according to  claim 38 , wherein the curing step comprises passing the coated elongated member through a heating device to heat cure the coating material. 
     
     
       48. The method according to  claim 38 , wherein the coating material is a first coating material, the method further comprising the step of coating the continuous elongated member with a second coating material prior to coating the continuous elongated member with the first material. 
     
     
       49. The method according to  claim 38 , wherein the coating material is a first coating material, the method further comprising the step of coating the continuous elongated member with a second coating material after coating the continuous elongated member with the first material. 
     
     
       50. The method according to  claim 38 , further comprising recoating the continuous elongated member with the coating material so as to form a second substantially uniform and continuous layer of coating material on the outer surface. 
     
     
       51. The method according to  claim 38 , wherein the coating step comprises providing a coating die and continuously passing the elongated member therethrough. 
     
     
       52. A method for forming a thin walled microtube, comprising the steps of:
   providing a continuous elongated member having an outer surface, the member being at least partially formed of a soluble material, the continuous elongated member being a continuous thin walled tube;        providing a coating material, the coating material comprising a silicone compound, the compound being curable such that the coating material cures into a substantially non - porous silicone;        coating the outer surface of the elongated member with the coating material in a substantially continuous process so as to form a substantially uniform and continuous layer of coating material on the outer surface;        curing the layer of coating material so as to form a substantially uniform and continuous layer of substantially non - porous silicone on the outer surface;        at least partially dissolving the elongated member; and        purging the at least partially dissolved member from the silicone layer;        whereby an elongated microtube of substantially non - porous silicone is formed.     
     
     
       53. A method of forming a portion of a gas exchange device having a plurality of thin walled microtubes, comprising the steps of:
   forming a plurality of coated members, each coated member being formed by the steps of:      providing a continuous elongated member having an outer surface, the member being at least partially formed of a soluble material;        providing a coating material, the coating material comprising a silicone compound, the compound being curable such that the coating material cures into a substantially nonporous silicone;        coating the outer surface of the elongated member with the coating material in a substantially continuous process so as to form a substantially uniform and continuous layer of coating material on the outer surface;        curing the layer of coating material so as to form a substantially uniform and continuous layer of substantially non - porous silicone on the outer surface;          grouping the plurality of coated members into a bundle having a first end and a second end with a bundle body extending therebetween;        potting the first end of the bundle with a potting material so as to form a first potted end interconnecting and sealing the coated members to each other;        potting the second end of the bundle with a potting material so as to form a second potted end interconnecting and sealing the coated members to each other;        cutting off a portion of each of the first and second potted ends such that the coated members are cut and the elongated members are at least partially exposed;        at least partially dissolving the elongated members; and        purging the at least partially dissolved members from the silicone layers.     
     
     
       54. A method for forming a thin walled microtube, comprising the steps of:
   providing a continuous elongated member having an outer surface, the member being at least partially formed of a soluble material, the continuous elongated member being a continuous thin walled tube;        providing a coating material, the coating material being curable such that the material becomes a solid;        coating the outer surface of the elongated member with the coating material in a substantially continuous process so as to form a substantially uniform and continuous layer of coating material on the outer surface;        curing the layer of coating material so as to form a substantially uniform and continuous solid layer on the outer surface;        at least partially dissolving the elongated member; and        purging the at least partially dissolved member from the solid layer;        whereby an elongated tube of solid material is formed.     
     
     
       55. The method according to  claim 1 , wherein the continuous elongated member is substantially completely formed of a material that is at least partially soluble. 
     
     
       56. The method according to  claim 1 , wherein the continuous elongated member has a side to side outside dimension less than  400  microns. 
     
     
       57. The method according to  claim 54 , wherein the continuous elongated member is substantially completely formed of a material that is at least partially soluble. 
     
     
       58. The method according to  claim 54 , wherein the continuous elongated member has a side to side outside dimension less than  400  microns. 
     
     
       59. A method for forming a thin walled microtube, comprising the steps of:
   providing a continuous elongated member having an outer surface, the member being at least partially formed of a soluble material, the continuous elongated member being a continuous thin walled tube;        providing a coating material, the coating material being curable such that the material becomes a solid;        providing a coating die;        passing the elongated member through the coating die so as to coat the outer surface of the elongated member with the coating material and form a substantially uniform and continuous layer of coating material on the outer surface;        curing the layer of coating material so as to form a substantially uniform and continuous solid layer on the outer surface;        at least partially dissolving the elongated member; and        purging the at least partially dissolved member from the solid layer;      
       
         whereby an elongated tube of solid material is formed. 
       
     
     
       60. A method for forming a thin walled microtube, comprising the steps of:
   providing a continuous elongated member having an outer surface, the member being at least partially formed of a water soluble material;        providing a coating material, the coating material comprising a silicone compound, the compound being curable such that the coating material cures into a substantially non - porous silicone;        coating the outer surface of the elongated member with the coating material in a substantially continuous process so as to form a substantially uniform and continuous layer of coating material on the outer surface, wherein the coating material is a first coating material, the method further comprising the step of coating the continuous elongated member with a second coating material prior to coating the continuous elongated member with the first material;        curing the layer of coating material so as to form a substantially uniform and continuous layer of substantially non - porous silicone on the outer surface;        at least partially dissolving the elongated member using water; and        purging the at least partially dissolved member from the silicone layer;        whereby an elongated microtube of substantially non - porous silicone is formed.     
     
     
       61. A method for forming a thin walled microtube, comprising the steps of:
   providing a continuous elongated member having an outer surface, the member being at least partially formed of a water soluble material;        providing a coating material, the coating material comprising a silicone compound, the compound being curable such that the coating material cures into a substantially non - porous silicone;        coating the outer surface of the elongated member with the coating material in a substantially continuous process so as to form a substantially uniform and continuous layer of coating material on the outer surface;        curing the layer of coating material so as to form a substantially uniform and continuous layer of substantially non - porous silicone on the outer surface;        recoating the continuous elongated member with the coating material so as to form a second substantially uniform and continuous layer of coating material on the outer surface;        at least partially dissolving the elongated member using water; and        purging the at least partially dissolved member from the silicone layer;        whereby an elongated microtube of substantially non - porous silicone is formed.     
     
     
       62. A method for forming a thin walled microtube, comprising the steps of:
   providing a continuous elongated member having an outer surface, the member being at least partially formed of a water soluble material;        providing a coating material, the coating material being curable such that the material becomes a solid;        coating the outer surface of the elongated member with the coating material in a substantially continuous process so as to form a substantially uniform and continuous layer of coating material on the outer surface;        curing the layer of coating material so as to form a substantially uniform and continuous solid layer on the outer surface;        recoating the continuous elongated member with the coating material so as to form a second substantially uniform and continuous layer of coating material on the outer surface;        at least partially dissolving the elongated member using water; and        purging the at least partially dissolved member from the solid layer;        whereby an elongated tube of solid material is formed.