Fine fiber filter media and processes
Fine fiber products including fiber webs, as well as related assemblies, systems and methods, are described. In some embodiments, fiber webs described herein may include fine fibers and relatively low amounts of degraded polymer formed during a fiber extrusion process. The fiber webs may be used for filter media applications.
1. A fiber web comprising:
a first layer and a second layer, wherein each of the first and second layers comprises a plurality of meltblown fibers having an average fiber diameter between about 0.1 microns and about 1.5 microns, wherein the second layer has the same composition as the first layer, and wherein the fiber web has:
a mean pore size of greater than about 0.1 microns and less than about 2.0 microns;
a surface area of greater than or equal to about 1.5 m 2 /g and less than or equal to about 6 m 2 /g;
a water permeability of greater than about 0.2 ml/min·cm 2 ·psi, wherein determining the water permeability comprises passing deionized water through the fiber web at a pressure of 20 psi until 1,000 ml of permeate has been collected;
a permeate turbidity of less than about 8 NTU, wherein determining the permeate turbidity comprises passing a dispersion of ISO 12103-1-A2 silica fine test dust in deionized water at a concentration of 1,500 ppm through the fiber web at a pressure of 30 psi until 50 ml of permeate is collected, and measuring turbidity of the collected permeate;
a basis weight between about 15 g/m 2 and about 200 g/m 2 ; and
a thickness between about 0.002 inches and about 0.02 inches,
wherein the fiber web has a bubble point between about 1.5 microns and about 20 microns, wherein the bubble point is measured according to the standard ASTM F-316-80 Method B, BS6410.
2. The fiber web of claim 1 , wherein the fiber web has a basis weight between about 30 g/m 2 and about 200 g/m 2 .
3. The fiber web of claim 1 , wherein the fiber web has a consistency of basis weight across the fiber web of about 3.0 standard deviations or less.
4. The fiber web of claim 1 , wherein the fiber web has a thickness between about 0.006 inches and about 0.016 inches.
5. The fiber web of claim 1 , wherein the fiber web has a consistency of thickness across the fiber web of about 3.0 standard deviations or less.
6. The fiber web of claim 1 , wherein the plurality of meltdown fibers have an average fiber diameter of less than about 1.0 microns.
7. The fiber web of claim 1 , wherein the plurality of meltblown fibers have an average fiber diameter of less than about 0.6 microns.
8. The fiber web of claim 1 , comprising a solidity of greater than or equal to about 10% and less than about 70%.
9. The fiber web of claim 1 , comprising a solidity of greater than or equal to about 25% and less than about 55%.
10. The fiber web of claim 1 , comprising a mean pore size of greater than about 0.2 microns and less than about 1.5 microns.
11. The fiber web of claim 1 , comprising a mean pore size of greater than about 0.3 microns and, less than about 1.0 microns.
12. The fiber web of claim 1 , wherein the fiber web has an air permeability of greater than about 2 and less than about 35 CFM.
13. The fiber web of claim 1 , wherein the fiber web has an air permeability of greater than about 2 and less than about 25 CFM.
14. The fiber web of claim 1 , wherein the fiber web has a water permeability of greater than about 0.2 ml/min·cm 2 ·psi and less than about 4 ml/min·cm 2 ·psi.
15. The fiber web of claim 1 , wherein the fiber web has an initial permeate flux greater than about 5 ml/min·cm 2 and less than about 200 ml/min·cm 2 .
16. The fiber web of claim 1 , wherein the fiber web has an initial permeate flux greater than about 5 ml/min·cm 2 and less than about 60 ml/min·cm 2 .
17. The fiber web of claim 1 , wherein the fiber web has a final permeate flux greater than about 1.5 ml/min·cm 2 and less than about 100 ml/min·cm 2 .
18. The fiber web of claim 1 , wherein the fiber web has a final permeate flux greater than about 2 ml/min·cm 2 and less than about 30 ml/min·cm 2 .
19. The fiber web of claim 1 , wherein the fiber web has a permeate turbidity of less than about 5 NTU.
20. The fiber web of claim 1 , wherein the fiber web has a permeate turbidity of less than about 2.5 NTU.
21. A filter element comprising the fiber web of claim 1 .
22. A method comprising passing a liquid through the fiber web of claim 1 .
23. The fiber web of claim 1 , wherein the fiber web is formed by stacking at least the first layer and the second layer.
24. The fiber web of claim 1 , wherein the fiber web is formed by laminating at least the first layer and the second layer.
25. The fiber web of claim 1 , wherein the fiber web is formed by subjecting at least the first layer and the second layer to a calendering process.
26. The fiber web of claim 1 , wherein the fiber web has a ratio of bubble point to mean pore size of less than about 3:1, wherein the bubble point is measured according to the standard ASTM F-316-80 Method B, BS6410.
27. The fiber web of claim 1 , wherein the fiber web has a ratio of bubble point to mean pore size of between about 2:1 and about 3:1, wherein the bubble point is measured according to the standard ASTM F-316-80 Method B, BS6410.
28. The fiber web of claim 1 , wherein the fiber web has a bubble point between about 1.5 microns and about 10 microns, wherein the bubble point is measured according to the standard ASTM F-316-80 Method B, BS6410.
29. The fiber web of claim 1 , the fiber web has a surface area greater than about 2.0 m 2 /g and less than or equal to about 6 m 2 /g.