Filtration media with improved dust loading

Abstract

To provide filter media that exhibit improved dust loading on an upstream face.SOLUTION: Filter media comprise: a downstream layer 110 of filter material in a corrugated configuration defining peaks 112 and valleys 114, where the downstream layer of filter material has a capture efficiency of at least 10% and a mean corrugation depth of less than 2.0 mm; and an upstream layer 120 of fibers extending across the peaks of the downstream layer of filter material, where the upstream layer of fibers has a mean fiber diameter of at least 10 microns, and a solidity of less than 10%.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] This application is filed as an international patent application claiming priority to U.S. Provisional Patent Application No. 62 / 825,188, filed March 28, 2019, the contents of which are incorporated herein by reference in their entirety.

[0002] The technology disclosed herein relates generally to filtration media, and more particularly to filtration media with improved dust loading. [Background technology]

[0003] The life of a filtration media is limited at least in part by dust collection and in part by particulates collected by the filtration media. As the volume and mass of particulates on and within the upstream surface of the filtration media increases, the filtration media becomes increasingly resistant to receiving fluid flow. Resistance to airflow through the filtration media is indicated by a differential pressure measurement between the upstream and downstream sides of the filtration media when the flow rate is constant, or by a reduction in airflow when the differential pressure remains constant. An increase in the differential pressure measurement indicates increasing resistance to fluid flow, and a relatively high differential pressure measurement indicates the end of the filtration media's usable life. Summary of the Invention [Problem to be solved by the invention]

[0004] The technology disclosed herein relates to filtration media that exhibit improved dust loading on the upstream surface of the filtration media, which can extend the useful life of the filtration media. [Means for solving the problem]

[0005] In some embodiments, the filtration media has a downstream layer of filtration material in a corrugated configuration defining peaks and valleys, and an upstream layer of fibers extending across the peaks of the downstream layer of filtration material. The downstream layer of filtration material has a capture efficiency of at least 10%. The downstream layer of filtration material has an average corrugation depth of less than 2.0 mm. The upstream layer of fibers has an average fiber diameter of at least 10 microns. The upstream layer of fibers has a solidity of less than 10%.

[0006] In some such embodiments, a plurality of fibers in the upstream layer of fibers are wrinkled. Additionally or alternatively, the downstream layer of filtration material has a capture efficiency of 20% to 40%. Additionally or alternatively, the downstream layer of filtration material comprises cellulose fibers. Additionally or alternatively, the cellulose fibers comprise wet-laid cellulose fibers. Additionally or alternatively, the downstream layer of filtration material comprises synthetic fibers. Additionally or alternatively, the upstream layer of fibers comprises polymeric fibers. Additionally or alternatively, the downstream layer of filtration material comprises fibers having an average fiber diameter of 4 to 30 microns. Additionally or alternatively, the upstream layer of fibers is not freestanding. Additionally or alternatively, the upstream layer of fibers is an end layer or upstream surface layer, and the upstream layer of fibers is in direct contact with the downstream layer of filtration material. Additionally or alternatively, the downstream layer of filtration material defines corrugations having an average corrugation depth greater than 0.23 mm. Additionally or alternatively, the upstream layer of fibers is non-corrugated.

[0007] Some embodiments of the technology disclosed herein are directed to a method of constructing a filtration medium. A spatial structure is created on a layer of filtration material. A layer of fibers is deposited over the spatial structure of the filtration material. The filtration material has a capture efficiency of at least 10%. The layer of fibers has an average fiber diameter of at least 10 microns.

[0008] In some such embodiments, a plurality of fibers within the layer of fibers are wrinkled. Additionally or alternatively, the layer of filtration material has a capture efficiency of 20% to 40%. Additionally or alternatively, the layer of filtration material includes wet-laid cellulose fibers. Additionally or alternatively, the layer of filtration material includes synthetic fibers. Additionally or alternatively, the layer of fibrous is not self-supporting. Additionally or alternatively, the layer of filtration material includes fibers having an average fiber diameter of 4 to 30 microns. Additionally or alternatively, forming the spatial structures includes forming corrugations within the filtration material. Additionally or alternatively, the layer of filtration material is corrugated with an average corrugation depth greater than 0.23 mm. Additionally or alternatively, the layer of filtration material is corrugated with an average corrugation depth less than 1.0 mm. Additionally or alternatively, forming the spatial structures includes depositing the spatial structures on an upstream surface of the filtration material.

[0009] Some other embodiments disclosed herein relate to another filtration medium having a downstream layer of filtration material and an upstream layer of fibers. The downstream layer of filtration material has a retention efficiency of at least 10%, and the upstream layer of fibers has an average fiber diameter of at least 10 microns and a solidity of less than 10%. The spatial structure defines an average void distance between the upstream layer of fibers and the downstream layer of filtration material of greater than 0.11 mm.

[0010] In some such embodiments, the downstream layer of filtration material has spatial structures that protrude perpendicular to the length and width of the filtration medium. Additionally or alternatively, the spatial structures have corrugations defined by the downstream layer of filtration material. Additionally or alternatively, the spatial structures are embossments defined by the downstream layer of filtration material. Additionally or alternatively, the spatial structures are stacks arranged between the upstream layer of fibers and the downstream layer of filtration material. Additionally or alternatively, the upstream layer of fibers is not freestanding. Additionally or alternatively, the upstream layer of fibers is non-corrugated. Additionally or alternatively, the downstream layer of filtration material is non-corrugated. Additionally or alternatively, the average gap distance between the upstream layer of fibers and the downstream layer of filtration material is less than 1.0 mm.

[0011] It will be understood that the downstream and upstream features (e.g., layers, surfaces, sides, etc.) or components thereof of the filtration medium are positioned such that, in use, the features are located upstream and downstream, respectively, in the direction of flow of the fluid being filtered by the filtration medium.

[0012] Capture efficiency may be determined for an unpleated flat sheet (which can be corrugated or non-corrugated) with 0.78 micron monodisperse polystyrene latex sphere particles at 20 feet / minute (6.1 meters / minute) according to ASTM Standard F1215-89.

[0013] As used herein, "solidity" is the percentage of the total volume of a layer of a thickness that is composed of solid material (rather than gas and space) measured at a particular pressure.

[0014] "ISO Fine Test Dust" is dust with a size distribution specified by standard ISO12103-1(2016).

[0015] As used herein, the phrase "void structure" refers to the void or void region, the structure that defines the space between the downstream layer of filtration material and the upstream layer of fibers, where the void space or void space is a volume that defines gas and air, rather than a solid structure such as a layer of filtration media, a layer of fibers, or another material or structure. The void structure can be defined by the configuration of the downstream layer of filtration material, or it can be a separate component / material arranged between the downstream layer of filtration material and the upstream layer of fibers. [Brief explanation of the drawings]

[0016] [Figure 1] 1 depicts an exemplary filtration medium consistent with the technology disclosed herein. [Figure 2] 1 depicts another exemplary filtration medium consistent with the technology disclosed herein. [Figure 3] 1 is a graph illustrating the relationship between differential pressure and dust collection for example filtration media. [Figure 4]10 is a graph showing differential pressure versus dust collection for additional exemplary filtration media; [Figure 5] 10 is a graph showing differential pressure versus dust collection for additional exemplary filtration media; [Figure 6] 10 is a graph showing differential pressure versus dust collection for additional exemplary filtration media; [Figure 7] 1 is a graph showing the relationship between average gap distance between layers and improved dust holding capacity for various filter media examples. [Figure 8] 1 is another exemplary filtration medium consistent with the technology disclosed herein. [Figure 9] 1 is yet another exemplary filtration medium consistent with the technology disclosed herein. [Figure 10] 1 is an exemplary flow diagram consistent with the techniques disclosed herein. [Figure 11] 1 is a graph showing the relationship between differential pressure and dust collection for various filter material layer corrugation depths. [Figure 12] 1 is a graph showing differential pressure versus dust collection by various filtration media. [Figure 13] 1 depicts an exemplary filtration media structure. DETAILED DESCRIPTION OF THE INVENTION

[0017] It should be noted that the drawings are provided primarily for clarity and, as a result, are not drawn to scale. Moreover, various structures / components, including, but not limited to, fasteners and the like, may be shown diagrammatically or removed from some or all of the figures to better illustrate aspects of the depicted embodiment or where the inclusion of such structures / components is not necessary for understanding the various exemplary embodiments described herein. However, the absence of such structures / components from showing / depicting in a particular drawing should not be construed as limiting the scope of the various embodiments in any way.

[0018] The present technology may be more fully understood and appreciated in view of the following detailed description of various embodiments in conjunction with the accompanying drawings.

[0019] The technology disclosed herein relates to filtration media that exhibit improved dust loading on the upstream surface of the filtration media. The improved dust loading can extend the useful life of the filtration media. Filtration media consistent with the technology disclosed herein are generally fluid filters. In various implementations, the filtration media are intended as particle filters, particularly for gaseous fluids such as air.

[0020] FIG. 1 depicts an exemplary filtration medium 100 consistent with the technology disclosed herein. Filtration medium 100 has a downstream layer of filtration material 110 and an upstream layer of fibers 120. The downstream layer of filtration material 110 is of a corrugated or grooved configuration. The upstream layer of fibers 120 is generally non-corrugated (non-grooved). The exemplary filtration medium 100 and corresponding components can have the same components, parameters, and properties as other examples described herein, except where clearly inconsistent.

[0021] The downstream layer of filtration material 110 can be various types of filtration materials and combinations of filtration material types. In some embodiments, the downstream layer of filtration material 110 contains cellulosic fibers. In some embodiments, the downstream layer of filtration material 110 contains synthetic fibers. In some embodiments, the downstream layer of filtration material 110 contains polymeric fibers. The downstream layer of filtration material 110 can incorporate multiple layers of filtration material in various embodiments. In various embodiments, the downstream layer of filtration material 110 is self-supporting in the sense that, once pleated, the downstream layer of filtration material 110 exhibits a stiffness that allows it to maintain the pleated configuration under gravity and / or forces experienced during filtration operation. In some embodiments, the corrugations defined by the downstream layer of filtration material 110 increase the stiffness of the self-supporting filtration material 110. In one example, the stiffness of the filtration material 110 can be quantified using Gurley stiffness, which in some cases can be at least 2000 mg. However, in some cases, the Gurley stiffness can be less than 2000 mg. Gurley stiffness can be calculated using Gurley Stiffness Test Council industry standards TAPPI #T543OM-16(2016) and ASTM D6125-97(2007).

[0022] The size of the fibers incorporated into the downstream layer 110 of filtration material can depend on the type of fiber. Generally, the fibers incorporated into the downstream layer 110 of filtration material have a variety of fiber diameters. The fibers incorporated into the downstream layer 110 of filtration material can have an average fiber diameter ranging from approximately 4 to 30 microns. The average fiber diameter is determined using Scandium M software from ResAlta Research Technologies, based in Golden, Colorado, USA. A portion of the filtration medium is viewed through a scanning electron microscope (SEM) so that 30 sample fibers and representative diameters can be identified by the user and recorded in the software. The software measures the cross-section for each fiber and calculates the average, minimum, maximum, and standard deviation for all selected fibers. In some embodiments, the fibers in the downstream layer 110 of filtration material have an average fiber diameter of at least 20 microns. The fibers incorporated into the downstream layer 110 of filtration material can have an average fiber diameter of, for example, 4 to 20 microns, 10 to 15 microns, 15 to 20 microns, 20 to 25 microns, or 10 to 30 microns.

[0023] The downstream layer 110 of filtration material has a retention efficiency of at least 10%, where retention efficiency is determined for an unpleated, flat sheet (which can be corrugated or non-corrugated) of 0.78 micron monodisperse polystyrene latex sphere particles at 20 feet / minute (6.1 meters / minute) according to ASTM Standard F1215-89. In some embodiments, the downstream layer 110 of filtration material has a retention efficiency of at least 20%. In some embodiments, the downstream layer 110 of filtration material has a retention efficiency of at least 90%. In some embodiments, the downstream layer 110 of filtration material has a retention efficiency of 10% to 80%, 20% to 40%, 60% to 99%, or 30% to 70%.

[0024] In one example, the downstream layer 110 of filtration material has about 80% cellulose fibers by weight. In some examples, the downstream layer 110 of filtration material has about 20% binder by weight. The binder can be, for example, latex or acrylic. The basis weight of the downstream layer 110 of filtration material can vary, but in one example, the basis weight is 96 g / m 2 is.

[0025] The corrugations 116 of the downstream layer 110 of filtration material define a plurality of alternating peaks 112 and valleys 114 spanning the length L of the filtration media 100. As used herein, "peak" and "valley" do not refer to a particular orientation of the corrugations in space; rather, the terms "peak" and "valley" are used herein to describe corrugations that protrude in opposite directions. While the corrugations depicted herein are generally sinusoidal, the corrugations can have other shapes. In some embodiments, the corrugations can be discontinuously incorporated into the curvature of the groove, such as one or more folds extending down the length of the groove. Furthermore, while the peaks and valleys are generally equally opposed, in some embodiments, the peaks can have a different magnitude than the valleys.

[0026] The corrugations in the downstream layer 110 of filtration material can have an average corrugation depth greater than 0.23 mm. The corrugations in the downstream layer 110 of filtration material generally have an average corrugation depth less than 4.0 mm. In various embodiments, the filtration material 110 has an average corrugation depth less than 2.0 mm. The corrugations in the downstream layer 110 of filtration material can have an average corrugation depth less than 1.5 mm. In some embodiments, the corrugations in the downstream layer 110 of filtration material have an average corrugation depth between 0.23 mm and 0.65 mm. Corrugation depth D is defined as the z-direction distance between a peak 112 and an adjacent valley 114 of the filtration material 110, where the z-direction is perpendicular to the length L and width W of the filtration material 110. The average corrugation depth is the average of a sample of corrugation depths measured across the filtration material 110, and can have a sample size of at least 5%, 10%, 15%, or 20% of the total corrugation depth of the filtration material 110.

[0027] The upstream layer of fibers 120 generally extends across the peaks 112 of the downstream layer of filtration material 110. In various embodiments, the upstream layer of fibers 120 is not attached to the downstream layer of filtration material 110 and remains separate from the downstream layer of filtration material 110. Alternatively, the upstream layer of fibers 120 can be bonded to the peaks 112 with an adhesive in some embodiments, while in other embodiments, the material forming at least a portion of the fibers in the upstream layer of fibers 120 is self-adhered to the downstream layer of filtration material 110 forming the peaks 112. The upstream layer of fibers 120 can be self-adhered, for example, when uncured (or wet) fibers are deposited across the downstream layer of filtration material 110 and allowed to cure (or dry). In some embodiments, the upstream layer of fibers 120 is a relaxed fiber, meaning that the fibers in the upstream layer of fibers 120 are substantially not bonded to one another. In some such embodiments, the fibers in the upstream layer of fibers 120 are not completely bonded to one another. In some embodiments, the upstream layer of fibers 120 can be a scrim material. The scrim material can be, for example, a woven, nonwoven, or knitted fabric. In some embodiments, the upstream layer of fabric 120 can have one or more layers that combine, for example, a first layer of fabric with a scrim material.

[0028] The upstream layer of fibers 120 generally extends across a substantial portion of the downstream layer of filtration material 110. In some embodiments, the upstream layer of fibers 120 extends across the entire downstream layer of filtration material 110. While the downstream layer of filtration material 110 is corrugated, the upstream layer of fibers 120 is non-corrugated and generally flat. However, the upstream layer of fibers 120 is not completely flat because portions of the upstream layer of fibers 120 located between adjacent peaks 112 of the downstream layer of filtration material 110 can flex in response to gravity. Furthermore, some fibers within the upstream layer of fibers 120 can extend outward from the plane defined by the length L and width W directions of the filtration medium 100 and extend beyond the general plane defined by the upstream layer of fibers 120. Generally speaking, the upstream layer of fibers 120 is substantially absent from the valleys 114 of the downstream layer of filtration material 110.

[0029] The corrugations 116 defined by the downstream layer of filtration material 110 are the type of spatial structure that defines the voids between the downstream layer of filtration material 110 and the upstream layer of fibers 120. Specifically, the corrugations 116 define the spatial structure. In various embodiments, such voids between the layers are greater than the average void distance D defined between the downstream layer of filtration material 110 and the upstream layer of fibers 120. mean In the presently depicted example, the widthwise gap distance defined between the downstream layer of filtration material 110 and the upstream layer of fibers 120 is generally constant. Therefore, the average gap distance D mean can be calculated by determining the total cross-sectional area A (in a plane extending through length L and in the Z direction) along length L between the downstream layer of filtration material 110 and the upstream layer of fibers 120, and then dividing cross-sectional area A by the length L of the filtration media 100.

[0030] In some embodiments, the average gap distance D between the downstream layer 110 of filtration material and the upstream layer 120 of fibers mean The average gap distance D between the downstream layer 110 of filtration material and the upstream layer 120 of fibers is greater than 0.11 mm. mean is generally less than 2.0 mm. The average gap distance D between the downstream layer of filtration material 110 and the upstream layer of fibers 120 mean can be less than 1.0 mm in various embodiments. The average gap distance D between the downstream layer of filtration material 110 and the upstream layer of fibers 120 mean can be less than 0.7 mm.

[0031] For purposes of this disclosure, the total cross-sectional area and the average void distance D between the downstream layer 110 of filtration material and the upstream layer 120 of fibers mean is a theoretical calculation that assumes that the fibers in the upstream layer of fibers 120 do not extend past the peaks 112 of the downstream layer of filtration material 110 toward the valleys 114 (into the voids between layers 110 and 120). In other words, the calculation assumes that the downstream side of the upstream layer of fibers 120 is perfectly flat.

[0032] Generally, the solidity of the upstream layer of fibers 120 is less than the solidity of the downstream layer of filtration material 110. As used herein, "solidity" is the percentage of the total volume of a layer that is composed of solid material (rather than gas and space) at a thickness measured at a particular pressure. Solidity is calculated by the following equation:

number

number

[0033] The upstream layer of fibers 120 generally has a solidity of less than 10%. In some embodiments, the upstream layer of fibers 120 has a solidity of less than 8%. In some embodiments, the upstream layer of fibers 120 has a solidity of between 2% and 9%.

[0034] The upstream layer of fibers 120 generally has a basis weight less than the basis weight of the downstream layer of filtration material 110. The upstream layer of fibers 120 has a basis weight of 1 to 45 g / m 2 or 15 to 40 g / m 2 In some embodiments, the upstream layer of fibers may have a basis weight of about 21 g / m 2 or 30 g / m 2 In some embodiments, the basis weight of the upstream layer 120 of fibers is between 2 and 10 g / m 2The weight may range from 1000 to 10 ...

[0035] In various embodiments, the upstream layer of fibers 120 contains fibers having an average fiber diameter greater than 10 microns. In various embodiments, the upstream layer of fibers 120 contains fibers having an average fiber diameter of at least 15 microns. In some embodiments, the upstream layer of fibers 120 contains fibers having an average fiber diameter of at least 20 microns with a standard deviation of 2. The upstream layer of fibers 120 contains fibers having an average fiber diameter of less than 1.0 mm. The upstream layer of fibers 120 generally contains fibers having an average fiber diameter of less than 0.5 mm. The upstream layer of fibers 120 can contain fibers having an average fiber diameter of less than 0.1 mm. In some embodiments, the upstream layer of fibers 120 can contain coarser fibers than the fibers contained in the downstream layer 110 of filtration material.

[0036] The upstream layer of fibers 120 can contain various types and combinations of fibers. The fibers in the upstream layer of fibers 120 can be substantially continuous, such as meltblown or spunbond fibers, discontinuous, or a combination thereof. In some embodiments, the upstream layer of fibers 120 is a polymeric fiber. In some embodiments, a plurality of fibers in the upstream layer of fibers 120 are wrinkled, such as exemplary wrinkle 122. A wrinkle 122 in a fiber is a discontinuity in the curvature of the fiber, similar to a fold or pleat. Such wrinkled fibers can add loft to the upstream layer of fibers 120, which can reduce the relative solidity, for example, by increasing the thickness of the upstream layer of fibers 120 or by reducing the basis weight of the upstream layer of fibers 120 at the same thickness.

[0037] In various embodiments, the upstream layer of fibers 120 is not freestanding in the sense that the upstream layer of fibers 120 does not exhibit rigidity and cannot be pleated to maintain a pleated configuration under the force of gravity. The upstream layer of fibers 120 can be in direct contact with the downstream layer of filtration material 110. The upstream layer of fibers 120 can be directly connected to the downstream layer of filtration material 110 in the sense that there is no intervening material between the upstream layer of fibers 120 and the downstream layer of filtration material 110, except for an adhesive (if an adhesive is used).

[0038] While the filtration media 100 of the present application can incorporate a variety of other constituent layers, in various embodiments, the upstream layer of fibers 120 is the end layer within the filtration media, and is therefore positioned to have the greatest exposure to dust entering the filtration media 100.

[0039] As discussed above, in some embodiments, the upstream layer of fibers can have multiple layers, such as the first layer of fibers deposited on a scrim material depicted in FIG. 2. Similar to the embodiment described above with reference to FIG. 1, the presently described filtration media 200 has a downstream layer of filtration material 210 and an upstream layer of fibers 220. The downstream layer of filtration material 210 is of a corrugated configuration, defining a plurality of alternating peaks 212 and valleys 214 along its length. The upstream layer of fibers 220 extends across the peaks 212 of the downstream layer of filtration material 210. The upstream layer of fibers 220 is generally non-corrugated and can be considered generally flat. The exemplary filtration media 200 and corresponding components can have the same components, parameters, and properties as other examples described herein, except where clearly contradictory.

[0040] Unlike the embodiment described with reference to FIG. 1 , in the current example, upstream layer of fibers 220 includes first layer of fibers 222 and support layer 224. Support layer 224 is disposed between downstream layer of filtration material 210 and first layer of fibers 222. Support layer 224 contacts peaks 212 defined by the corrugations of downstream layer of filtration material 210. Support layer 224 can be bonded to peaks 212 through an adhesive or alternative method, and in some embodiments, support layer 224 and downstream layer of filtration material 210 are disconnected. In some examples, support layer 224 is generally free-standing in the sense that support layer 224 has rigidity through which support layer 224 can be pleated, while in other embodiments, support layer 224 is not free-standing. Support layer 224 can be a variety of materials and combinations of materials, and in some embodiments, support layer 224 is a mesh, such as a wire or polymer mesh. Generally, the support layer 224 itself does not exhibit filtration efficiency or pressure drop when filtering 0.78 micron particles.

[0041] 3 depicts test results measuring dust collection and differential pressure for three different exemplary filtration media using ISO Fine Test Dust. Each of the first comparative example 310, second comparative example 320, and third comparative example 330 incorporates a non-corrugated downstream layer of filtration material with a relatively upstream scrim layer abutting a relatively downstream sheet of cellulosic media. Each non-corrugated downstream layer of filtration material has the same composition and filtration characteristics.

[0042] The first comparative example 310 is only the downstream layer of filtration material. The second comparative example 320 and the third comparative example 330 each incorporate an upstream layer of fiber abutting the downstream layer of filtration material. Each upstream layer of fiber contains polyethylene-polypropylene (PE / PP) bicomponent fiber wet-laid onto the upstream layer of the scrim layer. The first upstream layer of fiber used in the second comparative example 320 was 12% solids, 21.5 g / m 2 The second upstream layer of fibers in the third comparative example 330 has a basis weight of 3% solids, 21.5 g / m, and an average fiber diameter of 30.45 microns. 2and an average fiber diameter of 27 microns. To test each comparative example, the periphery of the scrim (with the upstream layer of fiber for the second and third comparative examples) and the sheet of cellulose media are clamped together by a test fixture. Each comparative example 310, 320, 330 was tested twice.

[0043] The graph in FIG. 3 shows that the third comparative example 330 has a fiber density of about 50 g / m 2 The data demonstrates that the first comparative example 310 has a lower differential pressure across the filtration media after loading with 100% dust than the first comparative example 310 and the second comparative example 320. The data suggests that the presence of an upstream layer of fibers having a 12% solidity does not significantly affect the life of the filtration media, while the presence of an upstream layer of fibers having a 3% solidity does significantly affect the life of the filtration media. In various embodiments consistent with the current art, the upstream layer of fibers has a solidity of less than 10%.

[0044] FIG. 4 depicts further test results measuring dust collection and differential pressure for three different exemplary filtration media using ISO Fine Test Dust. Comparative Example 4 410, Comparative Example 5 420, and Comparative Example 6 430 each use the non-corrugated downstream layer of filtration material discussed above with reference to FIG. 3 (FIG. 3 has a relatively upstream scrim layer abutting a relatively downstream layer of cellulose media). Comparative Example 4 410 is the downstream layer of filtration material only, in this case the scrim layer and cellulose media are clamped together around their periphery for testing. Comparative Example 5 420 and Comparative Example 6 each incorporate an upstream layer of wet-laid fiber on a scrim layer. The third upstream layer of fiber in Comparative Example 5 420 is 21.5 g / m 2 The fourth upstream layer of fiber in the sixth comparative example 430 was 21.5 g / m2, and the fourth upstream layer was polyethylene terephthalate (co-PET) bicomponent fiber having a basis weight of 21.5 g / m2 and a solids content of 6%, the fiber having an average fiber diameter of 15 microns. 2 The test fixture clamped the scrim with the upstream fiber layer to a sheet of cellulose media around each of their peripheries for testing.

[0045] The graph in FIG. 4 shows that the sixth comparative example 430 has a tensile strength of at least about 50 g / m 2 The data demonstrates that the fourth comparative example 410 and the fifth comparative example 420 have a lower differential pressure after a dust load of greater than 15 microns. The data suggests that the presence of an upstream layer of fibers having an average fiber diameter of 15 microns does not appear to have a significant beneficial effect on the life of the filtration media, while the presence of an upstream layer of fibers having an average fiber diameter of 30 microns appears to have a beneficial effect on the life of the filtration media. In some embodiments, the upstream layer of fibers has an average fiber diameter greater than 15 microns. In various embodiments consistent with the current art, the upstream layer of fibers has an average fiber diameter of at least 20 microns with a standard deviation of 2.

[0046] As noted above, ISO Fine Test Dust was used in the tests associated with FIG. 4 , where the dust particles have a particular size range and distribution. In some other implementations, where the particles to be filtered have a different size range and / or size distribution than ISO Fine Test Dust, a different average fiber diameter of the fibers in the upstream layer of fibers may demonstrate improved filtration media life compared to media without the upstream layer of fibers. In some such implementations, the upstream layer of fibers can have an average fiber diameter of 10 microns, 12 microns, 14 microns, or 15 microns. In some such implementations, the upstream layer of fibers can have an average fiber diameter of at least 10 microns, 12 microns, 14 microns, or 15 microns.

[0047] Figure 5 depicts further test results using ISO Fine Test Dust to measure dust collection and differential pressure for four different exemplary filtration media. Each of the comparative examples incorporates a downstream layer of filtration material that is a sheet of cellulose media. Each sheet of cellulose media has approximately 80% cellulose fiber and 20% binder by weight, and an average fiber diameter of 15.8 microns.

[0048] The seventh comparative example 510 and the eighth comparative example 520 each had a density of about 96.1 g / m 2The seventh comparative example 510 is a sheet of cellulose media only. The eighth comparative example 52 ... 2 The scrim layer was constructed from polyethylene terephthalate / polypropylene (PET / PP) composite fibers having a basis weight of 1000 sq ft, a solids content of 7%, and incorporated an upstream layer of fibers containing fibers having an average fiber diameter of 38 microns.

[0049] The cellulose media sheets in the ninth comparative example 530 and the tenth comparative example 540 each had a weight of 114.5 g / m 2 and a capture efficiency of 33%. The sheets of cellulose media in ninth comparative example 530 and tenth comparative example 540 are each corrugated to define an average corrugation depth of 0.58 mm. Ninth comparative example 530 is a sheet of cellulose media only in a corrugated configuration. Tenth comparative example 540 additionally has an upstream layer of fibers abutting the upstream side of the corrugated filtration material. The upstream layer of fibers in tenth comparative example 540 is the same as the upstream layer of fibers in eighth comparative example 520. Thus, the layer of fibers in tenth comparative example 540 is 30 g / m 2 weighing 100g, having a solids content of 7%, and containing fibers with an average fiber diameter of 38 microns.

[0050] For testing, each of the exemplary filtration media is clamped around its respective periphery. If the exemplary incorporates an upstream layer of fiber, the upstream layer of fiber and the sheet of cellulose media are clamped together around their periphery for testing, such that the upstream layer of fiber abuts the upstream side of the corrugated sheet of cellulose media.

[0051] FIG. 5 shows that a corrugated downstream media layer in combination with a non-corrugated upstream fibrous layer (tenth comparative example 540) provides a fiber density of at least about 100 g / m 2 This demonstrates that the filter has a lower differential pressure after loading with dust greater than 1000 kJ / min, which has a favorable impact on the life of the filter media.

[0052] FIG. 6 also depicts test results measuring dust collection and differential pressure for six different exemplary filtration media. Each exemplary filtration media has a downstream layer of filtration material that is a sheet of cellulose media consistent with the seventh and eighth comparative examples discussed above. The eleventh comparative example 610 is a non-corrugated sheet of cellulose media only. The twelfth comparative example 620 is a non-corrugated sheet of cellulose media abutting an upstream layer of fibers. The thirteenth comparative example 630, the fourteenth comparative example 640, the fifteenth comparative example 650, and the sixteenth comparative example 660 are downstream corrugated sheets of cellulose media each with an abutting upstream layer of fibers. The upstream layer of fibers in each of the related comparative examples in FIG. 6 is the same layer of fibers as the tenth comparative example 540 discussed above.

[0053] The thirteenth, fourteenth, fifteenth, and sixteenth comparative examples have corrugations with different average corrugation depths. The corrugations defined by the thirteenth comparative example 630 have an average corrugation depth of 0.23 mm. The corrugations defined by the fourteenth comparative example 640 have an average corrugation depth of 0.39 mm. The corrugations defined by the fifteenth comparative example 650 have an average corrugation depth of 0.52 mm. The corrugations defined by the sixteenth comparative example 660 have an average corrugation depth of 0.65 mm.

[0054] The data show that incorporating an upstream layer of fiber into the non-corrugated downstream layer of the filtration material (12th Comparative Example 620) significantly increases filtration life compared to the non-corrugated layer alone of the filtration material (11th Comparative Example 610). Furthermore, for filtration media structures incorporating a non-corrugated upstream layer of fiber, the downstream filtration material having a maximum corrugation depth of 0.23 mm (13th Comparative Example 630) exhibits very similar (or only a very slight reduction) differential pressure when dust loads each of the filtration media compared to the filtration media structure with an upstream fibrous layer and a downstream filtration material without corrugations (12th Comparative Example 620).

[0055] Each of the comparative examples incorporating a corrugated downstream layer of filtration material (Comparative Examples 13-16) had a fiber density of at least 150 g / m 2 The minimum dust load is 50 g / m (for the 16th comparative example), but in some cases it is 50 g / m 2 or 100g / m2 12. At the minimum dust load of 12.25, it has a lower pressure drop than the comparative example having a non-corrugated downstream layer (comparative example 620).

[0056] The results shown in Figure 6 are surprising. The 16th comparative example 660 has a fiber density of about 70 g / m 2 The media having a maximum corrugation depth of 0.23 mm (Comparative Example 13 630) behaves much like the non-corrugated media of the filtration media structure with downstream filtration material having no corrugations (Comparative Example 12 620) when dust loads each of the filtration media.

[0057] Tests were conducted to determine whether the pressure drop improvement shown in FIG. 6 correlated with the average corrugation depth of the downstream layer of filtration material. FIG. 11 shows data associated with the eleventh comparative example 610 of FIG. 6 , which is a non-corrugated sheet of cellulose media only (without an upstream layer of fibers) compared to two corrugated sheets of cellulose media only (each without an upstream layer of fibers) with different average corrugation depths. The first cellulose media 710 has an average corrugation depth of 0.65 mm, and the second cellulose media 720 has an average corrugation depth of 0.23 mm. Surprisingly, FIG. 11 demonstrates that the average corrugation depth of the cellulose media only, without an upstream layer of fibers, does not represent a reduction in the media's differential pressure when dust is loaded onto the media. In fact, the corrugations of the first cellulose media 710 and the second cellulose media 720 represent a slightly increased differential pressure when dust is loaded onto the media compared to the non-corrugated cellulose media of the eleventh comparative example 610.

[0058] 7, on the other hand, shows the improvement in dust holding capacity of the twelfth comparative example 620, the thirteenth comparative example 630, the fourteenth comparative example 640, the fifteenth comparative example 650, and the sixteenth comparative example 660 (discussed above with reference to FIG. 6 ) in terms of the average gap distance between the upstream layer of fibers and the downstream layer of filtration material. The dust holding capacity is determined by ISO Fine Test Dust at a pressure drop of 9.6 inches H2O (2388 Pa) and a flow rate of 10.5 feet / minute (5.33 cm / sec). The improvement in dust holding capacity is a percentage based on the dust holding capacity of the twelfth comparative example 620, which has a zero average gap distance between the upstream layer of fibers and the downstream layer of filtration material because the downstream layer of filtration material is non-corrugated. Each of the thirteenth comparative example 630, the fourteenth comparative example 640, the fifteenth comparative example 650, and the sixteenth comparative example 660 has a D in FIG. 1 between the upstream layer of fibers and the downstream layer of filtration material. mean with the average void distance calculated as described above in the discussion of the calculation of

[0059] The graph in Figure 7 shows that, for the test parameters described above, dust holding capacity improves almost linearly with increasing average gap distance between the upstream layer of fiber and the downstream layer of filtration material when the average gap distance exceeds 0.11 mm. When the upstream layer of fiber and / or the downstream layer of filtration material have alternative configurations (such as constructed from alternative types and combinations of fiber), the minimum average gap distance can differ from 0.11 mm. "Minimum average gap distance" is defined as the average gap distance between layers and represents an improvement over the average gap distance between layers above which the dust holding capacity of the media is approximately zero.

[0060] FIG. 8 depicts another exemplary filtration medium 800 consistent with the technology disclosed herein. Similar to the exemplary embodiments depicted in FIGS. 1 and 2, filtration medium 800 has a downstream layer of filtration material 810 abutting an upstream layer of fibers 820. The upstream layer of fibers 820 may have a support layer similar to the support layer described above with reference to FIG. 2. The upstream layer of fibers 820 may be in direct contact with a sparse structure 830 on the downstream layer of filtration material 810. Exemplary filtration medium 800 and corresponding components may have the same components, parameters, and properties as other examples described herein, except where clearly inconsistent.

[0061] Although the downstream layer of filtration material 810 is non-corrugated, the presently depicted exemplary filtration media 800 has a particular average void distance D in the z direction between the upstream layer of fibers 820 and the downstream layer of filtration material 810. mean , for example, an average gap distance D of more than 0.11 mm and less than 2.0 mm, 1.0 mm, or 0.7 mm mean 8 demonstrates another structure for achieving this. Specifically, spatial structures 830 on downstream layer of filtration material 810 protrude in the z-direction toward upstream layer of fibers 820. In the current example, spatial structures 830 are a series of spaced apart elongated ribs extending along width W of filtration media 800 and spaced across length L of filtration media 800 at specified increments.

[0062] The spatial structures 830 can be defined by the downstream layer of filtration material 810 itself. For example, the spatial structures 830 can be formed by shaping the downstream layer of filtration material 810, such as through embossing. In some other embodiments, the spatial structures 830 can be separate components deposited on the upstream side 812 of the downstream layer of filtration material 810 or the downstream surface 822 of the upstream layer of fiber 820 before the upstream layer of fiber 820 is deposited on the upstream side 812 of the downstream layer of filtration material 810. By way of example, the spatial structures 830 can be a hot melt polymer, an epoxy resin, or an adhesive that can be deposited in an uncured state and then cured. As another example, the spatial structures can be preformed structural components that are bonded to one or both of the upstream layer of fiber 820 and the downstream layer of filtration material 810.

[0063] Since the spacing between the layers of filtration material 800 is generally uniform along the width W, the average gap distance D between the upstream layer of fibers 820 and the downstream layer of filtration material 810 is mean is the average gap distance D in the length L direction mean The average gap distance D in the length L direction is approximately equal to mean can be calculated, for example, by calculating the total cross-sectional area A of the voids between the layers (planes extending in the length L and z direction) and dividing the cross-sectional area A by the length L, similar to that discussed above with reference to FIG. 1 of the downstream layer of filtration material. mean is generally the maximum gap distance D between layers max In this case, the maximum gap distance between layers D max can be calculated based on the gap distance in the z direction between the peaks 832 of the spatial structure 830 and the upstream side 812 of the downstream layer 810 of filtration material.

[0064] Maximum gap distance D max can be calculated as an average similar to the average corrugation depth, as discussed above with reference to Figure 1. Where the spatial structure 830 contacts the downstream layer 810 of filtration material and the upstream layer 820 of fiber, the gap distance between layers 810 and 820 is zero since there are no gaps between layers 810 and 820 in the spatial structure 830. In some other embodiments, the average maximum gap distance D max In some embodiments, the average maximum gap distance D max In some embodiments, the average maximum gap distance D max is less than 1.5 mm.

[0065] 9 depicts another exemplary filtration medium 900 consistent with the technology disclosed herein. This exemplary filtration medium 900 is generally consistent with the exemplary filtration medium described above with reference to FIG. 8 and may have the same components, parameters, and properties as other examples described herein, except where clearly contradictory. Filtration medium 900 has a downstream layer 910 of filtration material abutting a sac structure 930 on an upstream layer 920 of fibers. The upstream layer 920 of fibers may or may not have a support layer.

[0066] While the downstream layer 910 of filtration media is non-corrugated, the presently depicted exemplary filtration media 900 has a particular average void distance D between the upstream layer 920 of fibers and the downstream layer 910 of filtration material. mean , for example, an average gap distance D of more than 0.11 mm and less than 2.0 mm, 1.0 mm, or 0.7 mm mean 9 demonstrates another structure for reaching downstream layer 910 of filtration material, etc. Specifically, spatial structures 930 on downstream layer 910 of filtration material protrude in the z-direction toward upstream layer 920 of fibers. In the current example, spatial structures 930 comprise a series of discrete bulges spaced across width W and length L of filtration media 900. Similar to the example of FIG. 8 , spatial structures 930 can be defined by downstream layer 910 of filtration material itself, or spatial structures 930 can be separate components deposited on upstream side 912 of downstream layer 910 of filtration material or downstream surface 922 of upstream layer 920 of fibers as described above.

[0067] Because the spacing between layers of filtration media 900 is not uniform along the width W or length L, the average void distance D mean is calculated based on measurements in both directions. Specifically, the average gap distance D mean can be calculated by calculating the total volume V between the upstream layer of fiber 920 and the downstream layer of filtration material 910, and dividing the total volume V by the area of ​​the sample (which is the length L multiplied by the width W). mean is generally the maximum gap distance D between layers max In this case, the maximum gap distance between layers D maxcan be calculated based on the gap distance in the z-direction between the peaks 932 of the spatial structure and the upstream side 912 of the downstream layer 910 of filtration material. max can be calculated as an average at multiple sample locations across the filtration media 900 in a manner similar to the average corrugation depth as discussed above with reference to FIG. 1. In some embodiments, the average maximum void distance D max In some embodiments, the average maximum gap distance D max In some embodiments, the average maximum gap distance D max is less than 1.5 mm.

[0068] 10 depicts a method 1000 consistent with embodiments of the technology disclosed herein. A filtration material is generally obtained 1010, a spatial structure is generated 1020, and a layer of fiber is deposited 1030 onto the filtration material.

[0069] The filtration material can be consistent with the filtration materials described herein. Typically, the filtration material has a retention efficiency of at least 10%, and in some embodiments, the filtration material has a retention efficiency of 20% to 40%. The filtration material typically incorporates fibers, and in some embodiments, can have an average fiber diameter of 4 to 30 microns. The filtration material can contain cellulose fibers, synthetic fibers, and the like. In some embodiments, the filtration material is constructed from wet-laid fibers, such as cellulose fibers, where a slurry formed of the fibers is dried to produce the filtration material.

[0070] The spatial structures are generally created 1020 in association with the filtration material, and the spatial structures can be created 1020 through a variety of techniques. For example, the filtration material can be corrugated. In such an example, a length of the filtration material is passed through a corrugating tool that creates alternating peaks and valleys across the length of the filtration material (as depicted in Figures 1 and 2). The corrugations can correspond to the corrugations discussed throughout this document. In another example, the spatial structures are created 1020 by depositing a hot melt polymer onto the upstream surface of the filtration material. In yet another example, the spatial structures are created 1020 by bonding pre-formed structures onto the filtration material.

[0071] A layer of fibers is deposited 1030 onto the spatial structure. Specifically, the layer of fibers is deposited 1030 on the upstream side of the filtration material, more specifically, across the spatial structure on the filtration material. In embodiments where the filtration material is corrugated, the layer of fibers is deposited 1030 to extend across the peaks of the corrugations of the filtration material. The layer of fibers can be deposited 1030 onto the spatial structure by pre-forming a layer of fibers and then laying the pre-formed layer of fibers across the spatial structure. For example, the layer of fibers can be formed by a wet-laying process, and the wet-laid layer of fibers can be deposited 1030 onto the spatial structure. In some alternative embodiments, as described above, the spatial structure can be deposited on a downstream surface of an upstream layer of fibers. In such embodiments, the upstream layer of fibers having a spatial structure can be bonded to a downstream layer of filtration material.

[0072] In some embodiments, the fibers are constructed using a coextrusion process to produce various configurations, such as bicomponent fibers having a sheath / core or side-by-side structure. In such embodiments, the fibers can be cut as staple fibers and wet-laid onto a support layer to form a layer of fibers.

[0073] Alternatively, the layer of fibers can be formed by the act of depositing 1030 fibers onto the spatial structure. In some embodiments, the layer of fibers is deposited 1030 by electrospinning fibers onto the spatial structure. In some embodiments, the layer of fibers is deposited 1030 by meltblowing polymeric fibers onto the spatial structure. In some embodiments, the layer of fibers is deposited 1030 by using spunbonding techniques to deposit polymeric fibers onto the spatial structure. In various embodiments, the layer of fibers is self-adhered to the spatial structure of the filtration material. The layer of fibers is deposited 1030 to define a generally planar configuration, although not necessarily perfectly planar, as discussed above.

[0074] In various embodiments, the layer of fibers is deposited 1030 directly onto the spatial structure of the filtration material. In some other embodiments, the layer of fibers is deposited 1030 onto a support layer, which is bonded to the spatial structure of the filtration material (to achieve a configuration similar to that depicted in FIG. 2). In some embodiments, the support layer is not bonded to the spatial structure of the filtration material, but is positioned to abut the spatial structure of the filtration material. The support layer can be similar to the support layer described above with reference to FIG. 2.

[0075] As discussed above, the fibers in the layer of fibers have an average fiber diameter of at least 10 microns and the ranges described in more detail above. In some embodiments, a plurality of the fibers in the layer of fibers are wrinkled. As further discussed above, in some embodiments, the layer of fibers is not freestanding.

[0076] FIG. 12 shows test results comparing the differential pressure of the fifteenth comparative example 650 with the seventeenth comparative example 670, where the fifteenth comparative example 650 had a downstream sheet of cellulose media corrugated to an average depth of 0.52 mm and a 30 g / m 2The seventeenth comparative example 670 has a scrim layer constructed of PET / PP composite fibers having a basis weight of 1.50 g and a solidity of 7%, and an abutting substantially flat upstream layer of fibers containing fibers having an average fiber diameter of 38 microns. The seventeenth comparative example 670 uses the same corrugated downstream sheet of cellulose media and the same upstream layer of fibers as the fifteenth comparative example, except that the upstream layer of fibers is also corrugated with an average corrugation depth of 0.52 mm. The upstream layer of fibers is positioned on the downstream layer of cellulose media such that the crests of the corrugations defined by the cellulose media abut the valleys of the corrugations defined by the upstream layer of fibers similar to the structure depicted in FIG. 13. For testing, the corrugated upstream layer of fibers is clamped to the downstream sheet of cellulose media around each of their respective peripheries. This configuration increases the average gap distance between the upstream layer of fibers and the downstream layer of filtration material.

[0077] A seventeenth comparative example 670 was tested and compared to two sets of data associated with the fifteenth comparative example 650. Figure 12 suggests that there is not a significant difference in the differential pressure across the two media when dust is loaded onto each media. Specifically, the benefit associated with corrugating the upstream layer of fiber is not apparent.

[0078] Exemplary Embodiments Embodiment 1. a downstream layer of filtration material in a corrugated configuration defining peaks and valleys, the downstream layer of filtration material having a capture efficiency of at least 10% and an average corrugation depth of less than 2.0 mm; an upstream layer of fibers extending over the peaks of the downstream layer of filtration material, wherein the upstream layer of fibers has an average fiber diameter of at least 10 microns, and the upstream layer of fibers has a solidity of less than 10%.

[0079] Embodiment 2. 14. The filtration medium of any one of embodiments 1 and 3-13, wherein the plurality of fibers in the upstream layer of fibers are wrinkled.

[0080] Embodiment 3. 14. The filtration medium of any one of embodiments 1-2 and 4-13, wherein the downstream layer of filtration material has a capture efficiency of 20% to 40%.

[0081] Embodiment 4. 14. The filtration medium of any one of embodiments 1-3 and 5-13, wherein the downstream layer of the filtration material comprises cellulose fibers.

[0082] Embodiment 5. 5. The filtration medium of embodiment 4, wherein the cellulose fibers comprise wet-laid cellulose fibers.

[0083] Embodiment 6. 14. The filtration medium of any one of embodiments 1-5 and 7-13, wherein the downstream layer of the filtration material comprises synthetic fibers.

[0084] Embodiment 7. 14. The filtration medium of any one of embodiments 1-6 and 8-13, wherein the upstream layer of fibers comprises polymeric fibers.

[0085] Embodiment 8. 14. The filtration medium of any one of embodiments 1-7 and 9-13, wherein the downstream layer of filtration material comprises fibers having an average fiber diameter of 4 to 30 microns.

[0086] Embodiment 9. 14. The filtration medium of any one of embodiments 1-8 and 10-13, wherein the upstream layer of fibers is not freestanding.

[0087] Embodiment 10. 14. The filtration medium of any one of embodiments 1-9 and 11-13, wherein the upstream layer of fibers is an end layer, and the upstream layer of fibers is in direct contact with the downstream layer of filtration material.

[0088] Embodiment 11. 14. The filtration medium of any one of embodiments 1-10 and 12-13, wherein the downstream layer of filtration material defines corrugations having an average corrugation depth greater than 0.23 mm.

[0089] Embodiment 12. 14. The filtration medium of any one of embodiments 1 to 11 and 13, wherein the upstream layer of fibers is non-corrugated.

[0090] Embodiment 13. 13. The filtration medium of any one of embodiments 1-12, wherein the downstream layer of filtration material is freestanding.

[0091] Embodiment 14. 1. A method of constructing a filtration medium, comprising: creating a spatial structure on a layer of filtration material, the filtration material having a capture efficiency of at least 10%; and depositing a layer of fibers over the spatial structure of the filtration material, the layer of fibers having an average fiber diameter of at least 10 microns.

[0092] Embodiment 15. 25. The method of any one of embodiments 14 and 16-24, wherein the plurality of fibers in the layer of fibers are wrinkled.

[0093] Embodiment 16. 25. The method of any one of embodiments 14-15 and 17-24, wherein the layer of filtering material has a capture efficiency of 20% to 40%.

[0094] Embodiment 17. 25. The method of any one of embodiments 14-16 and 18-24, wherein the layer of filtration material comprises wet-laid cellulose fibers.

[0095] Embodiment 18. 25. The method of any one of embodiments 14-17 and 19-24, wherein the layer of filtration material comprises synthetic fibers.

[0096] Embodiment 19. 25. The method of any one of embodiments 14 to 18 and 20 to 24, wherein the layer of fibers is not freestanding.

[0097] Embodiment 20. 25. The method of any one of embodiments 14-19 and 21-24, wherein the layer of filtration material comprises fibers having an average fiber diameter of 4 to 30 microns.

[0098] Embodiment 21. 25. The method of any one of embodiments 14 to 20 and 22 to 24, wherein forming spatial structures comprises forming corrugations in the layer of filtration material.

[0099] Embodiment 22. 25. The method of any one of embodiments 14-21 and 23-24, wherein the layer of filtering material is corrugated with an average corrugation depth of greater than 0.23 mm.

[0100] Embodiment 23. 25. The method of any one of embodiments 14 to 22 and 24, wherein the layer of filtering material is corrugated with an average corrugation depth of greater than 0.23 mm.

[0101] Embodiment 24. 24. The method of any one of embodiments 14-23, wherein forming spatial structures comprises depositing spatial structures on the upstream surface of the layer of filtration material.

[0102] Embodiment 25. a downstream layer of filtration material having a capture efficiency of at least 10%; an upstream layer of fibers having an average fiber diameter of at least 10 microns and a solidity of less than 10%; and a spatial structure defining an average void distance between the upstream layer of fibers and the downstream layer of filtration material that is greater than 0.11 mm.

[0103] Embodiment 26. 35. The filtration medium of any one of embodiments 25 and 27-34, wherein the downstream layer of filtration material has spatial structures that protrude perpendicular to the length and width of the filtration medium.

[0104] Embodiment 27. 35. The filtration medium of any one of embodiments 25-26 and 28-34, wherein the spatial structure is a corrugation defined by a downstream layer of filtration material.

[0105] Embodiment 28. 35. The filtration medium of any one of embodiments 25-27 and 29-34, wherein the spatial structure is an embossment defined by the downstream layer of filtration material.

[0106] Embodiment 29. 35. The filtration medium of any one of embodiments 25-28 and 30-34, wherein the spatial structure is an ordered stack between an upstream layer of fibers and a downstream layer of filtration material.

[0107] Embodiment 30. 35. The filtration medium of any one of embodiments 25-29 and 31-34, wherein the upstream layer of fibers is not freestanding.

[0108] Embodiment 31. 35. The filtration medium of any one of embodiments 25-30 and 32-34, wherein the upstream layer of fibers is non-corrugated.

[0109] Embodiment 32. 35. The filtration medium of any one of embodiments 25-31 and 33-34, wherein the downstream layer of filtration material is non-corrugated.

[0110] Embodiment 33. 35. The filtration medium of any one of embodiments 25-32 and 34, wherein the downstream layer of filtration material is freestanding.

[0111] Embodiment 34. 34. The filtration medium of any one of embodiments 25-33, wherein the average void distance between the upstream layer of fibers and the downstream layer of filtration material is less than 1.0 mm.

[0112] It should also be noted that, as used herein and in the appended claims, the phrase "configured to" describes a system, apparatus, or other structure that is constructed or configured to perform a particular task or adopt a particular configuration. The word "configured to" can be used interchangeably with similar words such as "disposed on," "constructed," "manufactured," and the like.

[0113] All publications and patent applications in this specification are indicative of the level of ordinary skill in the art to which this technology pertains, and are herein incorporated by reference to the same extent as if each individual publication or patent application was individually and specifically indicated by reference.

[0114] This application is intended to cover any adaptations or variations of the present subject matter. It is to be understood that the foregoing is intended to be illustrative, and not limiting.

Claims

1. a downstream layer of filtration material in a corrugated configuration defining peaks and valleys, said downstream layer of filtration material having at least 10% and no more than 99% capture efficiency and an average corrugation depth greater than 0.23 mm and less than 2.0 mm; an upstream layer of fibers extending across the peaks of the downstream layer of filtration material, the upstream layer of fibers having an average fiber diameter of at least 10 microns and less than 1.0 mm, the upstream layer of fibers having a solidity of greater than or equal to 2% and less than 10%; The capture efficiency is determined according to ASTM Standard F1215-89, and the solidity is calculated by the following equation: A filtration medium wherein the corrugated configuration is a spatial structure that defines voids between the upstream layer of fibers and the downstream layer of filtration material.

2. 10. The filtration media of claim 1, wherein the downstream layer of filtration material has a retention efficiency of between 20% and 40%.

3. 10. The filtration media of claim 1, wherein the upstream layer of filtration material contains fibers having an average fiber diameter of at least 20 microns.

4. 10. The filtration media of claim 1, wherein the downstream layer of filtration material is freestanding.

5. A filtration medium as described in claim 1, wherein the upstream layer of fibers is not freestanding.

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