Polymer blend, polymer solution composition and fibers spun from the polymer blend and filtration applications thereof

Abstract

The invention relates to a web or filter structure such as the filtration media comprising a collection of fiber comprising a first polymer and a second polymer in a fine fiber or fine fiber web structure. The combination of two polymers provides improved fiber rheology in that the fiber has excellent temperature and mechanical stability. The combination of polymers imparts the properties of elasticity or tackiness, which is desirable for adhering particles to the fiber web, with high temperature resistance.

Description

BRIEF DESCRIPTION OF THE FIGURES

FIGS. 1 and 2 represent SEM or scanning electron micrographs of polyurethane (TPU) fine fiber having carbon particles entrained in the fiber web.

FIG. 2 shows the fiber of FIG. 1, after heating. The fibers have melted and coalesced.

FIGS. 3 and 4 show a fine fiber web comprising the blended polymer materials of the invention.

FIGS. 5 and 6 show the fine fiber web of FIGS. 4 and 5 after heating.

FIG. 7 is a DSC scan that shows the thermal properties of two homopolymers and their polymer alloy, which was used to electrospin the fine fibers of the invention.

Claims

1. A fine fiber comprising and a first polymer comprising a polyurethane and a second polymer, wherein there is about 0.1 to 0.99 parts of the second polymer per part of the first polymer, wherein the fiber has a diameter of about 0.001 to 5 microns and the first polymer and the second polymer are miscible.

2. The fiber of claim 1 wherein the fine fiber has improved melt resistance compared to a fiber made from the first polymer alone.

3. The fiber of claim 1 wherein the fiber has a tacky surface suitable for adhering particles.

4. The fiber of claim 1 wherein the second polymer is an addition polymer or a condensation polymer.

5. The fiber of claim 1 wherein the first polymer comprises the reaction product of a polyfunctional isocyanate compound and a polymer forming compound with two or more reactive hydrogens.

6. The fiber of claim 5 wherein the isocyanate compound comprises a diisocyanate compound.

7. The fiber of claim 5 wherein the isocyanate compound is an aromatic isocyanate.

8. The fiber of claim 5 wherein the compound having the reactive hydrogen comprises a compound selected from the group consisting of a diol, triol, polyol, diamine, triamine or tetramine, or mixtures thereof.

9. The fiber of claim 1 further comprising a particle.

10. The fiber of claim 9 wherein the particle is an activated carbon.

11. The fiber of claim 1 wherein the fiber is electrospun from a solution of the first polymer and the second polymer.

12. The fiber of claim 11 wherein the fiber does not become molten at the temperature that corresponds to the boiling point of the solvent from which the fiber is electrospun.

13. The fiber of claim 11 wherein the fiber is electrospun onto a support layer to form an electrospun fiber layer.

14. The fiber of claim 13 wherein the support layer is a nonwoven web.

15. The fiber of claim 13 wherein the support layer comprises a cellulosic substrate, a cellulosic/synthetic substrate or a polymeric non-woven substrate.

16. The fiber of claim 13 wherein the fiber layer is removed from the support layer after electrospinning.

17. The fiber of claim 13 wherein the fine fiber diameter is about 0.01 to about 2 microns and the thickness of the layer is about 1 to 100 times the diameter of the fine fiber.

18. The fiber of claim 13 wherein the fiber layer thickness is about 1 to 5 times the diameter of the fine fiber.

19. The fiber of claim 13 wherein the fiber layer thickness is about 1 to 30 microns.

20. The fiber of claim 13 wherein the fiber layer is a bilayer of the fine fiber.

21. The fiber of claim 13 wherein the layer is a multilayer of the fine fiber.

22. A fine fiber comprising a polyamide polymer and a polyurethane polymer, wherein there is about 0.1 to 0.99 parts of a polyamide polymer per part of the polyurethane polymer, wherein the fiber has a diameter of about 0.001 to 5 microns and the polyamide and the polyurethane are miscible.

23. The fiber of claim 22 wherein the polyamide polymer is a nylon.

24. The fiber of claim 22 wherein the combination of the polyamide and the polyurethane provide increased temperature resistance to melting of the polyurethane.

25. The fiber of claim 22 wherein the fiber has a tacky surface suitable for adhering particles.

26. The fiber of claim 22 wherein the polyurethane comprises the reaction product of an isocyanate compound and a compound with a reactive hydrogen.

27. The fiber of claim 26 wherein the isocyanate compound comprises a diisocyanate compound.

28. The fiber of claim 26 wherein the isocyanate compound is an aromatic isocyanate.

29. The fiber of claim 26 wherein the compound having the reactive hydrogen comprises a compound selected from the group consisting of a diol, triol, polyol, diamine, triamine or tetramine, or mixtures thereof.

30. The fiber of claim 22 further comprising a particle.

31. The fiber of 30 wherein the particle is an activated carbon.

32. The fiber of claim 22 wherein the fiber is electrospun from a solution of the first polymer and the polyurethane.

33. The fiber of claim 32 wherein the fiber does not become molten at the temperature that corresponds to the boiling point of the solvent from which the fiber is electrospun.

34. The fiber of claim 32 wherein the fiber is electrospun onto a support layer to form a fine fiber layer.

35. The fiber of claim 34 wherein the support layer is a nonwoven web.

36. The fiber of claim 34 wherein the support layer comprises a cellulosic substrate, a cellulosic/synthetic substrate or a polymeric non-woven substrate.

37. The fiber of claim 34 wherein the fiber layer is removed from the support layer after electrospinning.

38. The fiber of claim 34 wherein the fine fiber diameter is about 0.01 to about 2 microns and the thickness of the layer is about 1 to 100 times the diameter of the fine fiber.

39. The fiber of claim 34 wherein the layer thickness is about 1 to 5 times the diameter of the fine fiber.

40. The fiber of claim 34 wherein the fiber layer thickness is about 1 to 30 microns.

41. The fiber of claim 34 wherein the fiber layer is a bilayer of the fine fiber.

42. The fiber of claim 34 wherein the fiber layer is a multilayer of the fine fiber

43. A method of forming a fine fiber layer comprising the steps of (a) forming a solution of a first polymer comprising a polyurethane and a second polymer;(b) electrospinning the solution onto a substrate to form a fine fiber layer; and(c) drying the layer sufficiently to remove substantially all the solvent from the layer.

44. The method of claim 43 wherein the second polymer is a polyamide.

45. The method of claim 44 wherein the polyamide is a nylon.

46. The method of claim 43 wherein the fiber has increased temperature resistance compared to a fiber made from the first polymer alone.

47. The method of claim 43 wherein the fiber has a tacky surface suitable for adhering a particle.

48. The method of claim 47 wherein the particle is an activated carbon.

49. The method of claim 43 wherein the fiber does not become molten at the temperature that corresponds to the boiling point of the solvent from which the fiber is electrospun.

50. The method of claim 43 wherein the solution is electrospun onto a support layer.

51. The method of claim 50 wherein the support layer is a nonwoven web.

52. The method of claim 51 wherein the support layer comprises a cellulosic substrate, a cellulosic/synthetic substrate or a polymeric non-woven substrate.

53. The method of claim 50 wherein the fiber layer is removed from the support layer after electrospinning.

54. The method of claim 43 wherein the fine fiber diameter is about 0.01 to about 2 microns and the thickness of the layer is about 1 to 100 times the diameter of the fine fiber.

55. The method of claim 43 wherein the layer thickness is about 1 to 5 times the diameter of the fine fiber.

56. The method of claim 43 wherein the fiber layer thickness is about 1 to 30 microns.

57. The method of claim 43 wherein the fiber layer is a bilayer of the fine fiber.

58. The method of claim 43 wherein the fiber layer is a multilayer of the fine fiber.