FLUOROPOLYMER FINE FIBER

• US 20090032475A1
• Filed: 08/01/2007
• Published: 02/05/2009
• Est. Priority Date: 08/01/2007
• Status: Active Grant

• Current Assignee: Donaldson Company Incorporated
• Original Assignee: Donaldson Company Incorporated
• Inventors: Ferrer, Ismael, Yang, Chuanfang
• Granted Patent: US 8,978,899 B2
• Time in Patent Office: Days
• US Class Current: 210/799
• CPC Class Codes: B01D 17/02 Separation of non-miscible liquids
• CPC Class Codes: B01D 17/04 Breaking emulsions
• CPC Class Codes: B01D 17/10 with stationary filtering elements
• CPC Class Codes: B01D 2239/025 comprising nanofibres apparatus incorporating such gas filtering material see B01D46/546
• CPC Class Codes: B01D 39/1623 of synthetic origin
• CPC Class Codes: B01D 46/546 using nano- or microfibres
• CPC Class Codes: D01D 10/00 Physical treatment of artificial filaments or the like during manufacture, i.e. during a continuous production process before the filaments have been collected finishing D02J
• CPC Class Codes: D01D 5/003 the material being a polymer solution or dispersion D01D5/0053 takes precedence
• CPC Class Codes: D01D 5/0046 the fibre formed by coagulation, i.e. wet electro-spinning
• CPC Class Codes: D01F 6/12 from polymers of fluorinated hydrocarbons
• CPC Class Codes: D01F 6/32 comprising halogenated hydrocarbons as the major constituent
• CPC Class Codes: D04H 1/728 by electro-spinning electro-spinning methods and apparatus D01D5/0007
• CPC Class Codes: D04H 3/016 characterised by the fineness
• CPC Class Codes: D06M 10/00 Physical treatment of fibres, threads, yarns, fabrics, or fibrous goods made from such materials, e.g. ultrasonic, corona discharge, irradiation, electric currents, or magnetic fields; Physical treatment combined with treatment with chemical compounds or elements
• CPC Class Codes: D06M 2101/22 Polymers or copolymers of halogenated mono-olefins
• CPC Class Codes: Y10T 428/24942 including components having same physical characteristic in differing degree
• CPC Class Codes: Y10T 428/268 Monolayer with structurally defined element
• CPC Class Codes: Y10T 442/10 Scrim [e.g., open net or mesh, gauze, loose or open weave or knit, etc.]
• CPC Class Codes: Y10T 442/60 Nonwoven fabric [i.e., nonwoven strand or fiber material]
• CPC Class Codes: Y10T 442/68 Melt-blown nonwoven fabric

Abstract

A layer of fluoropolymer fine fiber can be made. The fine fiber can be made by electrospinning from a solvent or a solvent blend. The layers of the invention are useful in general filtration of fluid streams including gaseous and liquid streams. The fine fiber layers are also useful as hydrophobic filtration layers that can be used to separate water from a hydrocarbon stream.

Claims

1. A fine fiber layer comprising a fine fiber, the fine fiber comprising a fluoropolymer comprising a fine fiber diameter of about 0.1 microns to about 10 microns, the fine fiber layer comprising a thickness of about 0.2 microns to about 30 microns and a basis weight of about 0.01 grams per square meter to about 10 grams per square meter.

2. The fine fiber layer of claim 1 wherein the fine fiber diameter is about 0.3 microns to 1.0 micron.

3. The fine fiber layer of claim 1 wherein the fine fiber diameter is about 0.3 microns to 0.5 microns.

4. The fine fiber layer of claim 1 wherein the fine fiber layer has an interfiber spacing of about 0.01 micron to 25 microns.

5. The fine fiber layer of claim 1 wherein the fine fiber layer has an interfiber spacing of about 0.1 micron to 10 microns.

6. The fine fiber layer of claim 1 wherein the fine fiber layer has permeability to air of about 0.1 m³/min/m² to 5.0 m³/min/m².

7. The fine fiber layer of claim 1 wherein the fine fiber layer has permeability to air of about 0.1 m³/min/m² to 1.0 m³/min/m².

8. The fine fiber layer of claim 1 wherein the fine fiber layer has permeability to air of about 0.2 m³/min/m² to 0.5 m³/min/m².

9. The fine fiber layer of claim 1 wherein the fine fiber layer has a contact angle to water of at least 90°

.

10. The fine fiber layer of claim 1 wherein the fine fiber layer has a contact angle to water of at least 120°

.

11. The fine fiber layer of claim 1 wherein the fine fiber layer has a contact angle to water of at least 130°

.

12. The fine fiber layer of claim 1 wherein the fine fiber layer comprises a substrate.

13. The fine fiber layer of claim 12 wherein the substrate comprises a woven substrate.

14. The fine fiber layer of claim 12 wherein the substrate comprises a non-woven substrate.

15. The fine fiber layer of claim 12 wherein the substrate comprises a prefilter, a filter layer, a woven cellulose backing, a synthetic polymer backing, a scrim, a fuel filter substrate, a high efficiency particulate air filter, or a combination thereof.

16. The fine fiber layer of claim 12 wherein the substrate comprises a nonwoven cellulose.

17. The fine fiber layer of claim 16 wherein the substrate comprises silicone.

18. The fine fiber layer of claim 1 wherein the fine fiber layer is disposed between at least two substrate layers.

19. The fine fiber layer of claim 18 wherein at least one of the at least two substrate layers comprises a scrim.

20. The fine fiber layer of claim 19 wherein the scrim comprises a polyester or a nylon.

21. The fine fiber layer of claim 19 wherein the scrim has a basis weight of about 15 g/m² to 75 g/m².

22. The fine fiber layer of claim 18 wherein at least one of the at least two substrate layers comprises substrate comprises a prefilter, a filter layer, a woven cellulose backing, a synthetic polymer backing, a fuel filter substrate, a high efficiency particulate air filter, or a combination thereof.

23. The fine fiber layer of claim 18 wherein at least one of the at least two substrate layers comprises cellulose, a glass fiber, a polyester, a resin saturated polyester, a nylon, or a blend of copolymer thereof.

24. The fine fiber of claim 23 wherein at least one of the at least two substrate layers is a nonwoven.

25. The fine fiber layer of claim 24 wherein the nonwoven is a meltblown nonwoven.

26. The fine fiber layer of claim 22 wherein at least one of the at least two substrate layers is impregnated with silicone.

27. The fine fiber layer of claim 18 wherein at least one of the at least two substrate layers further comprises an adhesive.

28. The fine fiber layer of claim 18 wherein at least one of the at least two substrate layers is combined using adhesive lamination or heat lamination.

29. The fine fiber layer of claim 12 wherein the total thickness of the fine fiber layer and the substrate is about 50 microns to 4 millimeters.

30. The fine fiber layer of claim 12 wherein the total thickness of the fine fiber layer and the substrate is about 200 microns to 2 millimeters.

31. The fine fiber layer of claim 12 wherein the total thickness of the fine fiber layer and the substrate is about 500 microns to 1 millimeter.

32. The fine fiber layer of claim 12 wherein the total thickness of the fine fiber layer and the substrate is about 50 microns to 500 microns.

33. The fine fiber layer of claim 1 wherein the fine fiber layer has a total thickness of about 1 to 5 fiber diameters when the fine fiber layer is viewed at an angle 90°

from the angle of fiber deposition.

34. The fine fiber layer of claim 1 wherein the fiber layer has a total thickness of about 1 micron to 30 microns when the fine fiber layer is viewed at an angle 90°

from the angle of fiber deposition.

35. The fine fiber layer of claim 1 wherein the fiber layer has a total thickness of about 2 microns to 5 microns when the fine fiber layer is viewed at an angle 90°

from the angle of fiber deposition.

36. The fine fiber layer of claim 1 wherein the fine fiber layer has a total thickness of less than 1 micron when the fine fiber layer is viewed at an angle 90°

from the angle of fiber deposition.

37. The fine fiber layer of claim 1 wherein the fine fiber layer has a basis weight of about 0.01 grams per square meter to 10 grams per square meter.

38. The fine fiber layer of claim 1 wherein the fine fiber layer has a basis weight of about 0.1 grams per square meter to 2 grams per square meter.

39. The fine fiber layer of claim 1 wherein the air permeability of the fine fiber layer is about 0.1 m³/min/m² to 5.0 m³/min/m².

40. The fine fiber layer of claim 1 wherein the air permeability of the fine fiber layer is about 0.1 m³/min/m² to 1.0 m³/min/m².

41. The fine fiber layer of claim 1 wherein the air permeability of the fine fiber layer is about 0.2 m³/min/m² to 0.5 m³/min/m².

42. The fine fiber layer of claim 15 wherein the LEFS efficiency is at least 99% when measured with 0.8 micron latex particles at 20 feet per minute.

43. The fine fiber layer of claim 15 wherein the pressure drop is less than about 3 mm H₂O at 20 feet per minute of air having 0.8 micron latex particles.

44. The fine fiber layer of claim 15 wherein the air flow through the fine fiber layer and substrate is at least 10 cfm at 125 Pa.

45. The fine fiber layer of claim 1 wherein the fluoropolymer comprises more than one monomer, wherein at least one of the more than one monomer is a fluorinated monomer.

46. The fine fiber layer of claim 45 wherein the fluorinated monomer comprises tetrafluoroethylene, hexafluoropropylene, chlorotrifluoroethylene, trifluoroethylene, a perfluoroalkylvinyl ether, a fluorinated acrylate, or a mixture thereof.

47. The fine fiber layer of claim 45 further comprising a nonfluorinated monomer.

48. The fine fiber layer of claim 47 wherein the nonfluorinated monomer comprises vinyl chloride, ethylene, propylene, methyl vinyl ether, or a mixture thereof.

49. The fine fiber layer of claim 45 wherein the fluoropolymer comprises a copolymer of tetrafluoroethylene and ethylene.

50. The fine fiber layer of claim 45 wherein the fluoropolymer comprises a copolymer of tetrafluoroethylene and hexafluoropropylene.

51. The fine fiber layer of claim 45 wherein the fluoropolymer comprises a copolymer of tetrafluoroethylene and a perfluorovinyl ether.

52. The fine fiber layer of claim 45 wherein the fluoropolymer comprises a terpolymer of hexafluoropropylene, tetrafluoroethylene, and ethylene.

53. The fine fiber layer of claim 45 wherein the fluoropolymer comprises a copolymer or terpolymer of vinylidene fluoride.

54. The fine fiber layer of claim 53 comprising at least 50 mole percent vinylidene fluoride.

55. The fine fiber layer of claim 54 further comprising at least one comonomer comprising tetrafluoroethylene, trifluoroethylene, chlorotrifluoroethylene, hexafluoropropylene, vinyl fluoride, pentafluoropropene, or any other monomer that readily copolymerizes with vinylidene fluoride.

56. The fine fiber layer of claim 55 comprising about 70 mole percent to 99 mole percent vinylidene fluoride and about 1 mole percent to 30 mole percent tetrafluoroethylene.

57. The fine fiber layer of claim 55 comprising about 70 mole percent to 99 mole percent vinylidene fluoride and about 1 mole percent to 30 mole percent hexafluoropropylene.

58. The fine fiber layer of claim 55 comprising about 70 mole percent to 99 mole percent vinylidene fluoride and about 1 mole percent to 30 mole percent trifluoroethylene.

59. The fine fiber layer of claim 55 comprising a terpolymer of vinylidene fluoride, trifluoroethylene, and tetrafluoroethylene.

60. The fine fiber layer of claim 53 wherein the fluoropolymer is a fluoroelastomer.

61. The fine fiber layer of claim 60 comprising a polymer comprising hexafluoropropylene.

62. The fine fiber layer of claim 60 comprising a polymer comprising tetrafluoroethylene.

63. The fine fiber layer of claim 61 comprising a polymer comprising tetrafluoroethylene.

64. The fine fiber layer of claim 45 wherein the fluorinated monomer comprises a fluorinated acrylic monomer.

65. The fine fiber layer of claim 64 wherein the fluorinated acrylic monomer is a fluorinated acrylate or methacrylate.

66. The fine fiber layer of claim 64 further comprising at least one monomer comprising an alkyl (meth)acrylate, a substituted alkyl (meth)acrylate, (meth)acrylic acid, a (meth)acrylamide, styrene, a substituted styrene, a vinyl halide, or a vinyl ester.

67. The fine fiber layer of claim 1 wherein the contact angle of water on the surface of a fine fiber layer is greater than 120°

.

68. The fine fiber layer of claim 1 wherein the contact angle of water on the surface of a fine fiber layer is at least 140°

.

69. The fine fiber layer of claim 1 comprising interfiber spaces of about 0.01 micron to 25 microns.

70. The fine fiber layer of claim 1 comprising interfiber spaces of about 0.1 micron to 10 microns.

71. The fine fiber layer of claim 1 wherein the fine fiber layer is crosslinked.

72. The fine fiber of claim 1 wherein the crosslinking is accomplished using an electron beam.

73. The fine fiber of claim 72 wherein the fine fiber is exposed to electron beam radiation of at least about 400 KGy at 90 Kvolts.

74. The fine fiber of claim 72 wherein the fine fiber is exposed to electron beam radiation of at least about 1000 KGy at 90 Kvolts.

75. The fine fiber layer of claim 1 further comprising an additive.

76. The fine fiber layer of claim 75 wherein the additive comprises an antioxidant, an antibacterial agent, a flame retardant agent, or a colorant.

77. A fine fiber layer, comprising a fine fiber comprising a fluoropolymer, the fine fiber comprising a diameter of about 0.1 microns to about 1 micron, the fine fiber layer comprising a thickness of about 0.3 microns to about 5 microns when the fine fiber layer is viewed at an angle 90°

from the angle of fiber deposition, a basis weight of about 0.1 grams per square meter to about 2 grams per square meter, and air permeability of about 0.1 m³/min/m² to 1.0 m³/min/m².

78. The fine fiber layer of claim 77 wherein the fiber is disposed on a substrate comprising silicone impregnated cellulose.

79. The fine fiber layer of claim 77 wherein the fiber is electrospun from a solution comprising 9% weight percent of the fluoropolymer in acetone.

80. The fine fiber layer of claim 77 wherein the fluoropolymer comprises, polyvinyledene fluoride-co-hexafluoropropylene, polyvinyledene fluoride-co-hexafluoropropylene-co-tetrafluoroethylene or polyvinyledene fluoride-co-tetrafluoroethylene.

81. The fine fiber layer of claim 77 wherein the fine fiber and substrate are exposed to electron beam radiation of at least 400 KGy at 90 Kvolts.

82. A method of separating water from fuel, the method comprising the steps of

(a) contacting a hydrocarbon liquid, the hydrocarbon liquid comprising a water impurity, with a separator layer comprising:

(i) a fine fiber layer comprising a fine fiber, the fine fiber comprising a fluoropolymer comprising a fiber diameter of about 0.1 microns to about 10 microns, the fine fiber layer comprising a thickness of about 0.2 microns to about 30 microns and a basis weight of about 0.01 grams per square meter to about 10 grams per square meter, and

(ii) a substrate comprising cellulose, glass fibers, polyester, nylon, a fuel filtration medium, or a blend thereof;

(b) forming a separated aqueous phase from the hydrocarbon liquid phase wherein the separated aqueous phase comprises the water impurity; and

(c) removing the aqueous phase from the hydrocarbon liquid phase.

83. The method of claim 82 wherein the hydrocarbon liquid is a fuel.

84. The method of claim 83 wherein the fuel comprises diesel fuel, jet fuel, biodiesel fuel, ethanol, butanol, or a blend thereof.

85. The method of claim 82 wherein the water impurity comprises dust, dirt, aggregates of organic matter, bacteria, or combinations thereof.

86. The method of claim 82 wherein the fine fiber layer is about 2 microns to 5 microns thick.

87. The method of claim 82 wherein the fine fiber diameter is about 0.5 microns to 5 microns.

88. The method of claim 82 wherein the fine fiber layer has a permeability to air of about 0.1 m³/min/m² to 1.0 m³/min/m².

89. The method of claim 82 wherein the fine fiber layer has a permeability to air of about 0.2 m³/min/m² to 0.5 m³/min/m¹.

90. The method of claim 82 wherein the fine fiber layer has a basis weight of about 0.01 g/m² to 10 g/m².

91. The method of claim 82 wherein the fine fiber layer has a basis weight of about 0.1 g/m² to 2 g/m².

92. The method of claim 82 wherein the water is dispersed throughout the hydrocarbon liquid at a concentration of about 200 to 30,000 parts per million.

93. The method of claim 82 wherein the water is present as a separate insoluble phase within the hydrocarbon liquid phase.

94. The method of claim 83 wherein the fuel comprises gasoline.

95. The method of claim 83 wherein the fuel comprises a diesel fuel.

96. The method of claim 83 wherein the fuel comprises an aviation fuel.

97. The method of claim 96 wherein the aviation fuel comprises a turbo jet fuel.

98. The method of claim 83 wherein the fuel comprises a biodiesel fuel.

99. The method of claim 83 wherein the fuel comprises ethanol, butanol, or a combination thereof.

100. The method of claim 82 wherein the hydrocarbon liquid is filtered through the separator layer at a rate of about 0.04 liters per minute to 1.5 liters per minute.

101. The method of claim 82 wherein the hydrocarbon liquid is filtered through the separator layer at a rate of about 1.67 L/min per square meter of separator layer to 62.50 L/min per square meter of separator layer.

102. The method of claim 82 wherein the hydrocarbon liquid is filtered through a separator layer of a rate of about 0.55 L/min per cubic centimeter bulk volume of the fluorocarbon fine fiber to 21.00 L/min per cubic centimeter bulk volume of the fluorocarbon fine fiber.

103. The method of claim 82 wherein up to about 3 weight percent of the water impurity is separated from the hydrocarbon liquid.

104. The method of claim 82 wherein up to 30,000 parts per million of the water impurity is separated from the hydrocarbon liquid at least at about 50% time weighted efficiency.

105. The method of claim 82 wherein up to 30,000 parts per million of the water impurity is separated from the hydrocarbon liquid at least at about 75% time weighted efficiency.

106. The method of claim 82 wherein up to 30,000 parts per million of the water impurity is separated from the hydrocarbon liquid at least at about 90% time weighted efficiency.

107. The method of claim 82 wherein the water impurity is drained to a receptacle after separation from hydrocarbon liquid fuel.

108. The method of claim 82 wherein the breakthrough time of the separator layer is at least 15 minutes.

109. The method of claim 82 wherein the breakthrough time of the separator layer is at least 50 minutes.

110. The method of claim 82 wherein the breakthrough time of the separator layer is at least 60 minutes.

111. The method of claim 82 wherein the breakthrough time of the separator layer is at least 100 minutes.

112. The method of claim 82 wherein the breakthrough time of the separator layer is at least 150 minutes.

113. The method of claim 82 wherein the pressure drop across the separator layer is about 2 psi or less.

114. The method of claim 82 wherein the pressure drop across the separator layer is about 0.7 psi or less.

115. The method of claim 82 wherein the pressure drop across the separator layer is about 0.1 psi.

116. A method of forming a fine fiber layer, the fiber comprising a fluoropolymer, the method comprising electrospinning the fluoropolymer from an electrospinning solution.

117. The method of claim 116 wherein the electrospinning solution comprises about 1 weight percent to 50 weight percent fluoropolymer.

118. The method of claim 116 wherein the electrospinning solution comprises about 9 weight percent to 15 weight percent fluoropolymer.

119. The method of claim 116 wherein the electrospinning solution comprises about 70 to 95% by weight of a solvent comprising tetrahydrofuran, acetone, methyl ethyl ketone, ethyl acetate, 4-methoxy-4-methyl-2-pentanol, ethyl lactate, or mixtures thereof.

120. The method of claim 119 wherein the solvent comprises a mixture of acetone or methyl ethyl ketone with about 5 to 50 weight percent of ethyl lactate.

121. The method of claim 120 wherein the solvent comprises about 20 weight percent to 50 weight percent of ethyl lactate

122. The method of claim 120 wherein the solvent comprises about 25 weight percent to 35 weight percent of ethyl lactate.

123. The method of claim 116 wherein the fluoropolymer comprises an aqueous composition in the form of a latex or dispersion.

124. The method of claim 123 wherein the solution further comprises about 50 volume percent or less of a cosolvent comprising methanol, isopropanol, acetone, methyl ethyl ketone, methyl perfluorobutyl ether, or a mixture thereof.

125. The method of claim 124 comprising about 30 volume percent or less of the cosolvent.

126. The method of claim 124 comprising about 10 volume percent or less of the cosolvent.