Fluoropolymer fine fiber

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 liqiud streams. The fine fiber layers are also useful as hydrophobic filtration layers that can be used to separate water from a hydrocarbon stream.

1 - 81 . (canceled) 
     
     
         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 m 3 /min/m 2  to 1.0 m 3 /min/m 2 . 
     
     
         89 . The method of  claim 82  wherein the fine fiber layer has a permeability to air of about 0.2 m 3 /min/m 2  to 0.5 m 3 /min/m 2 . 
     
     
         90 . The method of  claim 82  wherein the fine fiber layer has a basis weight of about 0.01 g/m 2  to 10 g/m 2 . 
     
     
         91 . The method of  claim 82  wherein the fine fiber layer has a basis weight of about 0.1 g/m 2  to 2 g/m 2 . 
     
     
         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.