HIGH PERFORMANCE FILTER MEDIA
Filter media comprising non-woven fiber webs having high performance are generally described. For instance, in some embodiments, a non-woven fiber web described herein has a relatively high value of gamma and/or a relatively high ratio of dust holding capacity to basis weight. As another example, in some embodiments, a non-woven fiber web described herein is capable of being loaded with dust relatively uniformly throughout its depth. This latter property may assist with increasing the gamma and/or the ratio of dust holding capacity to basis weight.
1 . A filter media, comprising:
a non-woven fiber web comprising fibers, wherein:
polypropylene makes up at least 75 wt % of the polymers in the non-woven fiber web;
the fibers in the non-woven fiber web have an average diameter of less than or equal to 15 microns;
the non-woven fiber web has a gamma of greater than or equal to 200;
a ratio of the dust holding capacity of the filter media to a basis weight of the filter media is greater than or equal to 1 gsm/gsm; and
the non-woven fiber web has a thickness of greater than 6 mils.
2 . A filter media, comprising:
a non-woven fiber web comprising fibers, wherein:
polypropylene makes up at least 75 wt % of the polymers in the non-woven fiber web;
the fibers in the non-woven fiber web have an average diameter of less than or equal to 15 microns;
the non-woven fiber web has a gamma of greater than or equal to 200; and
the non-woven fiber web is configured such that, after undergoing a NaCl loading process, a density of NaCl at a downstream surface of the non-woven fiber web is greater than or equal to 50% of a density of NaCl at an upstream surface of the non-woven fiber web.
3 . A filter media as in claim 1 , wherein the filter media further comprises a charged layer comprising non-continuous fibers.
4 - 9 . (canceled)
10 . A filter media as in claim 1 , wherein the filter media further comprises a non-woven fiber web comprising nanofibers.
11 . A filter media as in claim 10 , wherein the nanofibers have an average diameter of less than or equal to 300 nm.
12 . A filter media as in claim 1 , wherein the filter media further comprises a second non-woven fiber web also comprising fibers comprising polypropylene.
13 . A filter media as in claim 12 , wherein the fibers in the second non-woven fiber web have an average diameter that is less than the average diameter of the fibers in the non-woven fiber web.
14 . A filter media as in claim 12 , wherein the fibers in the second non-woven fiber web have an average diameter of less than or equal to 5 microns.
15 . A filter media as in claim 1 , wherein the non-woven fiber web is meltblown.
16 . A filter media as in claim 12 , wherein the second non-woven fiber web is meltblown.
17 . A filter media as in claim 1 , wherein the filter media further comprises a backer.
18 . A filter media as in claim 17 , wherein the backer has an air permeability of greater than or equal to 200 CFM.
19 . A filter media as in claim 17 , wherein the backer has a stiffness of greater than or equal to 300 mg.
20 - 23 . (canceled)
24 . A filter media as in claim 1 , wherein the non-woven fiber web has a mean flow pore size of greater than or equal to 20 microns.
25 . A filter media as in claim 1 , wherein the non-woven fiber web has an air permeability of greater than or equal to 20 CFM and less than or equal to 1300 CFM.
26 . (canceled)
27 . A filter media as in claim 1 , wherein the polypropylene has a melt flow rate of less than or equal to 2000.
28 . A filter media as in claim 1 , wherein the non-woven fiber web is hydrocharged.
29 . A filter media as in claim 1 , wherein the fibers in the non-woven fiber web have an average diameter of greater than or equal to 3 microns.
30 . A filter media as in claim 1 , wherein the non-woven fiber web has a solidity of less than or equal to 6%.
31 . A filter media as in claim 1 , wherein the non-woven fiber web has a dust holding capacity of greater than or equal to 20 gsm.