FILTER MEDIA INCLUDING A WAVED FILTRATION LAYER HAVING A GRADIENT
Filter media comprising a waved filtration layer having a gradient in a property and associated methods are provided. The waved filtration layer may include fibers that form one or more fiber webs. In some embodiments, the diameter of the fibers may vary across at least a portion of the thickness of the waved filtration layer to produce a gradient in fiber diameter. The gradient may be designed to impart beneficial properties to the filter media, such as low pressure drop and long lifetime. In some embodiments, the gradient may be characterized by mathematical equations that describe the change in fiber diameter across at least a portion of the thickness of the waved filtration layer. The filter media, described herein, may be particularly well-suited for applications that involve filtering liquids, though the media may also be used in other applications.
1 . A filter media, comprising:
a filtration layer comprising a coarse fiber web positioned adjacent to a fine fiber web; and
a support layer that holds the filtration layer in a waved configuration and maintains separation of peaks and troughs of adjacent waves of the filtration layer,
wherein:
the fine fiber web has an average fiber diameter of greater than or equal to about 0.02 microns and less than or equal to about 0.3 microns and has a basis weight of greater than or equal to about 0.01 g/m 2 and less than or equal to about 3 g/m 2 , and
the coarse fiber web has an average fiber diameter of greater than or equal to about 0.1 microns and less than or equal to about 30 microns and has a basis weight of greater than or equal to about 2 g/m 2 and less than or equal to about 30 g/m 2 ,
the average fiber diameter of the fine fiber web is less than the average fiber diameter of the coarse fiber web, and
the filter media has an initial pressure drop of greater than or equal to about 1.0 mm H 2 O and less than or equal to about 15.0 mm H 2 O.
2 . A filter media, comprising:
a filtration layer comprising a coarse fiber layer comprising a first coarse fiber web and a second coarse fiber web positioned adjacent to a fine fiber web, wherein the fine fiber web has an average fiber diameter of greater than or equal to about 0.02 microns and less than or equal to about 0.3 microns and has a basis weight of greater than or equal to about 0.01 g/m 2 and less than or equal to about 3 g/m 2 , and
wherein an average fiber diameter at four or more locations along a thickness of the coarse fiber layer is greater than or equal to any exponential function having the form:
B
min
(
exp
(
A
max
*
x
)
)
2
and less than or equal to any exponential function having the form:
B
max
(
exp
(
A
min
*
x
)
)
2
wherein:
B min is greater than or equal to about 1 micron and less than or equal to about 2 microns,
B max is greater than or equal to about 5 microns and less than or equal to about 15 microns,
A min is greater than about 0 and less than or equal to about 0.4,
A max is greater than or equal to about 0.7 and less than or equal to about 1.5,
x corresponds to a location along a thickness of at least a portion of the filtration layer and is normalized to have a value greater than or equal to 0 and less than or equal to 1, and
wherein:
the four or more locations along the thickness of the coarse fiber layer comprises a top surface location and a bottom surface location of the first coarse fiber web and a top surface location and a bottom surface location of the second coarse fiber web; and
a support layer that holds the filtration layer in a waved configuration and maintains separation of peaks and troughs of adjacent waves of the filtration layer.
3 . A filter media, comprising:
a filtration layer comprising a coarse fiber layer comprising a first coarse fiber web and a second coarse fiber web positioned adjacent to a fine fiber web, wherein the fine fiber web has an average fiber diameter of greater than or equal to about 0.02 microns and less than or equal to about 0.3 microns and has a basis weight of greater than or equal to about 0.01 g/m 2 and less than or equal to about 3 g/m 2 , and
wherein an average fiber diameter at two or more locations along an thickness of the coarse fiber layer is greater than or equal to any exponential function having the form:
B
min
(
exp
(
A
max
*
x
)
)
2
and less than or equal to any exponential function having the form:
B
max
(
exp
(
A
min
*
x
)
)
2
wherein:
B min is greater than or equal to about 1 micron and less than or equal to about 2 microns,
B max is greater than or equal to about 5 microns and less than or equal to about 15 microns,
A min is greater than about 0 and less than or equal to about 0.4,
A max is greater than or equal to about 0.7 and less than or equal to about 1.5,
x corresponds to a location along a thickness of at least a portion of the filtration layer and is normalized to have a value greater than or equal to 0 and less than or equal to 1, and
wherein the two or more locations along the thickness of the coarse fiber layer comprises a half thickness location of the first coarse fiber web and a half thickness location of the second coarse fiber web; and
a support layer that holds the filtration layer in a waved configuration and maintains separation of peaks and troughs of adjacent waves of the filtration layer.
4 . The filter media of claim 1 , wherein B min is greater than or equal to about 1.3 microns and less than about 2 microns.
5 . The filter media of claim 1 , wherein B max is greater than or equal to about 5 microns and less than about 8 microns.
6 . The filter media of claim 1 , wherein A min is greater than or equal to about 0.3 and less than about 0.4.
7 . The filter media of claim 1 , wherein A max is about 0.7.
8 . The filter media of claim 1 , wherein the fine fiber web is an electrospun fiber web.
9 . The filter media of claim 1 , wherein the coarse fiber web is a meltblown fiber web.
10 . The filter media of claim 1 , wherein the first and second coarse fiber webs are meltblown fiber webs.
11 . The filter media of claim 1 , wherein the fine fiber web has an average fiber diameter of greater than or equal to about 0.05 microns and less than or equal to about 0.15 microns.
12 . The filter media of claim 1 , wherein the coarse fiber web has an average fiber diameter of greater than or equal to about 0.2 microns and less than or equal to about 15 microns.
13 . The filter media of claim 1 , wherein the fine fiber web has a basis weight of greater than or equal to about 0.05 g/m 2 and less than or equal to about 0.8 g/m 2 .
14 . The filter media of claim 1 , wherein the coarse fiber web has a basis weight of greater than or equal to about 5 g/m 2 and less than or equal to about 20 g/m 2 .
15 . The filter media of claim 1 , wherein the filtration layer has a basis weight of greater than or equal to about 2 g/m 2 and less than or equal to about 30 g/m 2 .
16 . The filter media of claim 1 , wherein the filtration layer has a thickness of greater than or equal to about 2 mil and less than or equal to about 6 mil.
17 . The filter media of claim 1 , wherein the filtration layer has a mean flow pore size of greater than or equal to about 5 microns and less than or equal to about 25 microns.
18 . A filter media, comprising:
a filtration layer comprising a coarse fiber web positioned adjacent to a fine fiber web, wherein an average fiber diameter at two or more locations along a thickness of the fine fiber web and an average fiber diameter at two or more locations along a thickness of the coarse fiber web is greater than or equal to any exponential function having the form:
B
min
(
exp
(
A
max
*
x
)
)
2
and less than or equal to any exponential function having the form:
B
max
(
exp
(
A
min
*
x
)
)
2
wherein:
B min is greater than or equal to about 1.5 microns and less than or equal to about 3 microns,
B max is greater than or equal to about 12 microns and less than or equal to about 30 microns,
A min is greater than about 0 and less than or equal to about 1.2,
A max is greater than or equal to about 1.4 and less than or equal to about 1.75,
x corresponds to a location along a thickness of at least a portion of the filtration layer and is normalized to have a value greater than or equal to 0 and less than or equal to 1, and
wherein:
the two or more locations along the thickness of the fine fiber web comprises a top surface location and a bottom surface location, and
the two or more locations along the thickness of the coarse fiber web comprises a top surface location and a bottom surface location; and
a support layer that holds the filtration layer in a waved configuration and maintains separation of peaks and troughs of adjacent waves of the filtration layer.
19 . A filter media, comprising:
a filtration layer comprising a coarse fiber web positioned adjacent to a fine fiber web, wherein an average fiber diameter at one or more locations along an thickness of the fine fiber web and an average fiber diameter at one or more locations along an thickness of the coarse fiber web is greater than or equal to any exponential function having the form:
B
min
(
exp
(
A
max
*
x
)
)
2
and less than or equal to any exponential function having the form:
B
max
(
exp
(
A
min
*
x
)
)
2
wherein:
B min is greater than or equal to about 1.5 microns and less than or equal to about 3 microns,
B max is greater than or equal to about 12 microns and less than or equal to about 30 microns,
A min is greater than about 0 and less than or equal to about 1.2,
A max is greater than or equal to about 1.4 and less than or equal to about 1.75,
x corresponds to a location along an thickness of at least a portion the filtration layer and is normalized to have a value greater than or equal to 0 and less than or equal to 1, and
wherein:
the one or more locations along the thickness of the fine fiber web comprises a half thickness location of the fine fiber web, and
the one or more locations along the thickness of the coarse fiber web comprises a half thickness location of the coarse fiber web; and
a support layer that holds the filtration layer in a waved configuration and maintains separation of peaks and troughs of adjacent waves of the filtration layer.
20 . A filter media, comprising:
a filtration layer, wherein an average fiber diameter at three or more locations along an thickness of the filtration layer is greater than or equal to any exponential function having the form:
B
min
(
exp
(
A
max
*
x
)
)
2
and less than or equal to any exponential function having the form:
B
max
(
exp
(
A
min
*
x
)
)
2
wherein:
B min is greater than or equal to about 1.5 microns and less than or equal to about 3 microns,
B max is greater than or equal to about 12 microns and less than or equal to about 30 microns,
A min is greater than about 0 and less than or equal to about 1.2,
A max is greater than or equal to about 1.4 and less than or equal to about 1.75,
x corresponds to a location along a thickness of at least a portion of the filtration layer and is normalized to have a value greater than or equal to 0 and less than or equal to 1, and wherein the three or more locations along the thickness of the filtration layer comprises x is 0.25, x is 0.5, and x is 0.75; and
a support layer that holds the filtration layer in a waved configuration and maintains separation of peaks and troughs of adjacent waves of the filtration layer.
21 - 42 . (canceled)