Morphology-enhanced adsorption filter media

Abstract

Filter media are generally described that include a surface-treated fibrous web having one or more advantageous physical properties. Certain improvements in surface treated webs described herein may be achieved in a filter media comprising adsorbent particles. In some embodiments, the improvements herein relate to an advantageous distribution of cavities in surface-treated webs of filter media, such as those used in backing.

Description

Technical Field

[0001] The present invention generally relates to filter media, and more specifically, to filter media comprising a fiber web (e.g., a nonwoven fiber web) having an improved morphology. Background Technology

[0002] Filter media can be used in a variety of applications. For example, filter media can be used to remove contaminants from fluids. Some filter media may exhibit undesirable properties, such as low dust holding capacity and low filtration efficiency.

[0003] Therefore, improved filter media design is needed. Summary of the Invention

[0004] This article describes the filter media and related methods.

[0005] In one aspect, a filter medium is provided. According to some embodiments, the filter medium includes: a fiber web comprising a plurality of surface cavities, wherein: the average length of the synthetic fibers of the fiber web is less than or equal to 40 mm, the unfolded interface area ratio of the fiber web is greater than or equal to 0.1, and the cavities of the fiber web have an average cross-dimensional frequency of greater than or equal to 3,000 surface cavities / meter; and a plurality of adsorbent particles disposed on the fiber web.

[0006] Other advantages and novel features of this disclosure will become apparent from the following detailed description of several non-limiting embodiments of this disclosure when considered in conjunction with the accompanying drawings. In the event of any conflicting and / or inconsistent disclosures in this specification and in documents incorporated by reference, this specification shall prevail. Attached Figure Description

[0007] Non-limiting embodiments of this disclosure will be described by way of example with reference to the accompanying drawings, which are schematic and not intended to be drawn to scale unless otherwise stated. In the drawings, each identical or substantially identical component shown is generally indicated by a single reference numeral. For clarity, not every component is labeled in every drawing, nor is every component of every embodiment of this disclosure shown, unless illustration is required to enable those skilled in the art to understand the disclosure. In the drawings:

[0008] Figure 1 A schematic cross-sectional view of a surface-treated fiber web comprising a plurality of cavities of different shapes, according to some embodiments, is presented.

[0009] Figure 2A schematic cross-sectional view of a filter medium comprising a surface-treated fiber mesh backing and adsorbent particles, according to some embodiments, is presented.

[0010] Figures 3A to 3B A schematic cross-sectional view of a filter medium, including a surface-treated fiber mesh backing and additional layers, is presented according to some embodiments.

[0011] Figure 4 Cross-sectional measurements of the surface morphology of a surface-treated fiber mesh backing, applied to improve cavity morphology according to some embodiments, are presented; and

[0012] Figure 5 Cross-sectional measurements of the surface morphology of a control fiber mesh backing without any treatment to improve cavity morphology, according to some embodiments, are presented. Detailed Implementation

[0013] Filter media generally include fiber webs with advantageous properties. In some embodiments, the filter media and / or fiber webs described herein are surface-treated fiber webs comprising surface morphologies that produce enhanced physical properties. For example, a surface-treated fiber web (e.g., belonging to the filter media) may include a plurality of cavities formed on the surface of the fiber web and having an advantageous size distribution. The cavities can create a fiber web surface with an increased surface area, which can advantageously improve the dust holding capacity and / or air permeability of the filter media. The cavities may have a size distribution that facilitates the deposition of additional materials, such as particles, onto the fiber web. As further described below, the cavities may be formed in a surface treatment process, such as fluid enhancement. In some embodiments, the fiber web serves as a backing for adding one or more layers thereon to form the filter media. Filter media can be used in a variety of applications, including for the removal of airborne molecular contaminants (AMC), fuel cells, cabin air filtration, and HVAC filtration.

[0014] Figure 1 A non-limiting schematic cross-sectional view of the surface morphology of a surface-treated fiber web is provided. For example... Figure 1As shown, the surface-treated fiber web 103 has a high surface area created by the cavity 113. The surface-treated fiber web can be woven or nonwoven. In some embodiments, the use of a surface-treated nonwoven fiber web is particularly advantageous for use in filter media. A variety of suitable types of nonwoven fiber webs can be used as surface-treated fiber webs in the filter media described herein. For example, the filter media may include a surface-treated fiber layer comprising wet-laid nonwoven fiber webs, non-wet-laid nonwoven fiber webs (e.g., air-laid nonwoven fiber webs, carded nonwoven fiber webs), electrospun nonwoven fiber webs, and / or other types of nonwoven fiber webs.

[0015] The morphology (e.g., the morphology of the surface-treated fiber web 103) can be created by a surface treatment (e.g., fluid reinforcement) of the surface-treated fiber web. It should be understood that although the cavity is only explicitly shown on the top surface of the surface-treated fiber web, the cavity may exist on one or both sides of the surface-treated fiber web, as this disclosure is not so limited.

[0016] Some cavity morphologies offer particular advantages for filter media. For example, without being bound by any particular theory, small surface cavities can be associated with a uniform distribution of adsorbent particles across the surface of a surface-treated fiber web. Therefore, increasing the surface area of ​​a surface-treated fiber web by introducing cavities with advantageous morphologies (e.g., by preferentially introducing small and medium-sized cavities) can improve filter media performance. Thus, in some embodiments, this disclosure relates to surface-treated fiber webs with advantageous cavity morphologies.

[0017] Figure 2 A non-limiting schematic cross-sectional view of the filter medium is provided. Figure 2 The filter medium 252 shown includes a surface-treated fiber web 103 and adsorbent particles 221 disposed thereon. For example... Figure 2 As shown, adsorbent particles can be preferentially disposed within the cavities 113 of the surface-treated fiber web. Therefore, a greater number and / or more uniformly distributed number of cavities can be associated with a more uniformly distributed adsorbent particle, which can result in performance advantages for the filter media. Of course, it should be understood that the adsorbent particles do not need to be confined within the cavities (e.g., ...). Figure 2 Instead of being deposited on the surface shown), the adsorbent particles can be deposited on another surface of the surface-treated fiber web, as this disclosure is not so limiting. For example, in some embodiments, the adsorbent particles can form a layer on the surface-treated fiber web. The adsorbent particles are described in more detail below.

[0018] Of course, it should be understood that, although Figure 2 The filter medium is not shown to include additional layers, but filter medium 252 may include layers from... Figure 2Additional layers are omitted to improve visual clarity regarding features related to the cavity.

[0019] In addition to the surface layer, the filter media may include one or more additional layers. Figures 3A to 3B A schematic cross-sectional view of a multi-layer filter media, including a surface-treated fiber web and additional layers, is provided. Figure 3A A filter medium 452 is shown comprising an additional layer 463 at least partially disposed on a surface-treated fiber web 103 having a cavity 113. The filter medium has a three-layer structure, wherein the additional layer and the surface-treated fiber layer overlap and are separated from each other by a layer 465 which may contain adsorbent particles. Figure 3B A filter medium 450 is shown comprising an additional layer 461 at least partially disposed on a surface-treated fiber web 103 having a cavity 113. The filter medium has a bilayer structure and may contain additional materials (not shown) disposed on one or more layers. For example, in some embodiments, the bilayer structure comprises a plurality of adsorbent particles disposed between the surface-treated layer and the additional layer. The additional layers may have any of a variety of compositions and may perform any of a variety of functions within the filter medium, as discussed in more detail below.

[0020] As described above, the surface-treated fiber web may include a plurality of cavities having any of a variety of suitable morphologies. The cavities may have any of a variety of suitable shapes. In some embodiments, for example, the cavities are recesses (e.g., depressions having a relatively small aspect ratio of less than or equal to 10:1, 5:1, or 2:1 between the longest dimension of the cavity and the shortest dimension of the cavity parallel to the surface of the surface-treated fiber web). As another example, in some embodiments, the cavities are grooves (e.g., depressions having a high aspect ratio of more than 2:1, 5:1, or 10:1 between the longest dimension of the cavity and the shortest dimension of the cavity parallel to the surface of the surface-treated fiber web). The cavities are not limited to any particular depth, shape, or orientation, as this disclosure is not so limiting.

[0021] The area of ​​the cavity can exceed a suitable cutoff area. For example, multiple cavities can be selected to exclude cutoff areas less than or equal to 20 micrometers. 2 Less than or equal to 15 micrometers 2 Less than or equal to 10 micrometers 2 Less than or equal to 5 micrometers 2 Less than or equal to 2 micrometers 2 Less than or equal to 1 micrometer 2 or less than or equal to 0.05 micrometers 2 All cavities.

[0022] The area of ​​the cavity can be determined by using a scanning electron microscope (SEM) to examine a representative portion of the surface-treated fiber web (e.g., an area of ​​at least 10 × 10 cm²). 2 Images of the representative portion are imaged and analyzed to identify cavities. Images can be analyzed to increase contrast by setting the white balance to 0 and adjusting the black balance without blurring the boundaries between fibers and cavities in the image. Cavities can then be detected individually by using particle picking software (e.g., the "analyze Particle" tool in ImageJ) to identify enclosed and bounded dark areas in the image corresponding to cavities and to determine the area of ​​the cavities in the image plane. The cavities described herein can have any of a plurality of suitable depths. In some embodiments, the average depth of the plurality of cavities is greater than or equal to 0%, greater than or equal to 2%, greater than or equal to 5%, greater than or equal to 10%, greater than or equal to 15%, greater than or equal to 20%, greater than or equal to 25%, greater than or equal to 30%, greater than or equal to 35%, greater than or equal to 40%, greater than or equal to 45%, greater than or equal to 50%, greater than or equal to 55%, greater than or equal to 60%, greater than or equal to 65%, or greater than or equal to 70% of the thickness of the fiber web. In some embodiments, the average depth of the plurality of cavities is less than or equal to 75%, 70%, 65%, 60%, 55%, 50%, 45%, 40%, 35%, 30%, 25%, 20%, 15%, 10%, or 5% of the thickness of the fiber web. Combinations of these ranges are also possible (e.g., greater than or equal to 0% and less than or equal to 75%, or greater than or equal to 2% and less than or equal to 50%). Other ranges are also possible.

[0023] A laser system can be used to collect topographic images of the top and bottom surfaces of a surface-treated fiber web to measure the average depth of a plurality of cavities in the surface-treated fiber web. The average depth of a plurality of cavities on one side of the surface-treated fiber web can be estimated by identifying peaks on the surface of the surface-treated fiber web and determining the average depth of cavities between successive pairs of peaks. The average depth of the cavities can be expressed as a percentage of the average thickness of the surface-treated fiber web, which can be determined using techniques discussed elsewhere herein. An exemplary laser system that can be used is the Mate Gauge laser system used in the following embodiments.

[0024] The surface-treated fiber web described herein may comprise a plurality of cavities having any of a plurality of suitable average areas. In some embodiments, the surface-treated fiber web comprises a plurality of cavities having an average area greater than or equal to 1 micrometer. 2 5 micrometers or greater 2 10 micrometers or greater 2 ≥20 micrometers 2 30 micrometers or greater 2 40 micrometers or greater 2 50 micrometers or greater 2 ≥60 micrometers 2 70 micrometers or greater 2 ≥80 micrometers 2 ≥90 micrometers 2 ≥100 micrometers 2 ≥110 micrometers 2 ≥120 micrometers 2 ≥130 micrometers 2 or greater than or equal to 140 micrometers 2 In some embodiments, the surface-treated fiber web comprises a plurality of cavities having an average area of ​​less than or equal to 150 micrometers. 2 Less than or equal to 140 micrometers 2 Less than or equal to 130 micrometers 2 Less than or equal to 120 micrometers 2 Less than or equal to 110 micrometers 2 Less than or equal to 100 micrometers 2 Less than or equal to 90 micrometers 2 Less than or equal to 80 micrometers 2 Less than or equal to 70 micrometers 2 Less than or equal to 60 micrometers 2 Less than or equal to 50 micrometers 2 Less than or equal to 40 micrometers 2 Less than or equal to 30 micrometers 2 Less than or equal to 20 micrometers 2 Less than or equal to 10 micrometers 2 or less than or equal to 5 micrometers 2 Combinations of these ranges are also possible (e.g., greater than or equal to 1 micrometer). 2 and less than or equal to 150 micrometers 2 1 micrometer or greater 2 and less than or equal to 100 micrometers 2 or greater than or equal to 1 micrometer 2 and less than or equal to 50 micrometers2 Other ranges are also possible.

[0025] Of course, it should be understood that the plurality of cavities from each side of the surface-treated filter medium can each independently have an average area falling within one of the aforementioned ranges.

[0026] The area of ​​each cavity in the plurality of cavities can be determined by imaging a representative portion of the surface-treated fiber mesh using a scanning electron microscope (SEM) and by determining the area of ​​each imaged cavity using the steps described elsewhere in this document for determining the cavity area. The average area of ​​the cavities in the plurality of cavities can then be calculated by averaging the individual areas of the cavities.

[0027] As defined in this article, a large cavity is defined as a single cavity having a diameter greater than or equal to 1,000 micrometers. 2 The area of ​​the cavity is [missing information]. According to some embodiments, for a surface-treated fiber web, a large cavity having a relatively low average area can be advantageous. In some embodiments, the surface-treated fiber web comprises a plurality of cavities, wherein the average area of ​​the large cavity is less than or equal to 2,000 micrometers. 2 1,900 micrometers or less 2 Less than or equal to 1,800 micrometers 2 1,700 micrometers or less 2 Less than or equal to 1,600 micrometers 2 Less than or equal to 1,500 micrometers 2 Less than or equal to 1,400 micrometers 2 Less than or equal to 1,300 micrometers 2 1,200 micrometers or less 2 or less than or equal to 1,100 micrometers 2 In some embodiments, the surface-treated fiber web comprises a plurality of cavities, wherein the average area of ​​the large cavities is greater than 1,000 micrometers. 2 ≥1,100 micrometers 2 ≥1,200 micrometers 2 ≥1,300 micrometers 2 ≥1,400 micrometers 2 ≥1,500 micrometers 2 ≥1,600 micrometers 2 ≥1,700 micrometers 2 ≥1,800 micrometers 2 or greater than or equal to 1,900 micrometers 2 Combinations of these ranges are also possible (e.g., greater than 1,000 micrometers).2 And less than or equal to 2,000 micrometers 2 ≥1,100 micrometers 2 And less than or equal to 1,500 micrometers 2 or larger than 1,000 micrometers 2 And less than or equal to 1,300 micrometers 2 Other ranges are also possible.

[0028] Of course, it should be understood that the plurality of cavities from each side of the surface-treated filter medium can each independently have an average area of ​​a large cavity falling within one of the aforementioned ranges.

[0029] The area of ​​each cavity in the plurality of cavities can be determined by imaging a representative portion of the surface-treated fiber mesh using a scanning electron microscope (SEM) and by using the steps described elsewhere in this document for determining the cavity area to determine the area of ​​each imaged cavity. Then, the area can be determined by examining cavities exceeding 1,000 micrometers. 2 The average area of ​​the large cavity among the multiple cavities is calculated by averaging the areas of each cavity.

[0030] As defined in this article, a medium-sized cavity is defined as a single cavity having a diameter greater than or equal to 100 micrometers. 2 And less than or equal to 1,000 micrometers 2 The area of ​​the cavities. According to some embodiments, for surface-treated fiber webs, medium and large cavities having a relatively low average area can be advantageous. In some embodiments, the surface-treated fiber web comprises a plurality of cavities, wherein the medium and large cavities together have an average area of ​​less than or equal to 1,100 micrometers. 2 Less than or equal to 1,000 micrometers 2 900 micrometers or less 2 Less than or equal to 800 micrometers 2 700 micrometers or less 2 ≤600 micrometers 2 500 micrometers or less 2 ≤400 micrometers 2 ≤300 micrometers 2 ≤200 micrometers 2 or less than or equal to 150 micrometers 2 In some embodiments, the surface-treated fiber web comprises a plurality of cavities, wherein medium and large cavities together have an average area greater than 100 micrometers. 2 ≥150 micrometers 2 ≥200 micrometers 2≥300 micrometers 2 ≥400 micrometers 2 ≥500 micrometers 2 ≥600 micrometers 2 ≥700 micrometers 2 ≥800 micrometers 2 ≥900 micrometers 2 or greater than or equal to 1,000 micrometers 2 Combinations of these ranges are also possible (e.g., greater than 100 micrometers). 2 And less than or equal to 1,100 micrometers 2 ≥150 micrometers 2 And less than or equal to 1,000 micrometers 2 or larger than 100 micrometers 2 and less than or equal to 500 micrometers 2 Other ranges are also possible.

[0031] Of course, it should be understood that the plurality of cavities from each side of the surface-treated filter medium can each independently have an average area of ​​medium and large cavities falling within one of the aforementioned ranges.

[0032] The area of ​​each cavity in the plurality of cavities can be determined by imaging a representative portion of the surface-treated fiber mesh using a scanning electron microscope (SEM) and by using the steps described elsewhere in this document for determining the cavity area to determine the area of ​​each imaged cavity. Then, the area can be determined by examining cavities exceeding 100 micrometers. 2 The average area of ​​the medium and large cavities together is calculated by averaging the areas of each cavity.

[0033] The surface-treated fiber web described herein may comprise a plurality of cavities, the plurality of cavities covering any of a plurality of suitable percentages of the area of ​​the surface-treated fiber web. In some embodiments, the surface-treated fiber web comprises a plurality of cavities covering an area of ​​greater than or equal to 1%, greater than or equal to 5%, greater than or equal to 10%, greater than or equal to 15%, greater than or equal to 20%, greater than or equal to 25%, greater than or equal to 30%, or greater than or equal to 35% of the surface of the surface-treated fiber web. In some embodiments, the surface-treated fiber web comprises a plurality of cavities covering an area of ​​less than or equal to 40%, less than or equal to 35%, less than or equal to 30%, less than or equal to 25%, less than or equal to 20%, less than or equal to 15%, less than or equal to 10%, or less than or equal to 5% of the surface of the surface-treated fiber web. Combinations of these ranges are also possible (e.g., greater than or equal to 1% and less than or equal to 40%, greater than or equal to 1% and less than or equal to 30%, greater than or equal to 5% and less than or equal to 25%, or greater than or equal to 10% and less than or equal to 25%). Other ranges are also possible.

[0034] Of course, it should be understood that the plurality of cavities from each side of the surface-treated filter medium can each independently have an area coverage falling within one of the aforementioned ranges.

[0035] The area of ​​each cavity among the plurality of cavities can be determined by imaging a representative portion of the surface-treated fiber web using a scanning electron microscope (SEM) and by determining the area of ​​each imaged cavity using the steps described elsewhere in this document for determining cavity area. The average percentage of the surface-treated fiber web area occupied by the cavities among the plurality of cavities can then be calculated by adding the areas occupied by the cavities and dividing by the total area of ​​the representative portion of the surface-treated fiber web.

[0036] The surface-treated fiber web described herein can have any of a number of suitable transverse dimension cavity frequencies. In some embodiments, the transverse dimension cavity frequency of the surface-treated fiber web is greater than or equal to 3000 cavities / m, greater than or equal to 3500 cavities / m, greater than or equal to 4000 cavities / m, greater than or equal to 4500 cavities / m, greater than or equal to 5000 cavities / m, greater than or equal to 5500 cavities / m, greater than or equal to 6000 cavities / m, greater than or equal to 6500 cavities / m, greater than or equal to 7000 cavities / m, greater than or equal to 7500 cavities / m, greater than or equal to 8000 cavities / m, greater than or equal to 8500 cavities / m, greater than or equal to 9000 cavities / m, or greater than or equal to 9500 cavities / m. In some embodiments, the transverse dimension cavity frequency of the surface-treated fiber web is less than or equal to 10,000 cavities / m, less than or equal to 9,500 cavities / m, less than or equal to 9,000 cavities / m, less than or equal to 8,500 cavities / m, less than or equal to 8,000 cavities / m, less than or equal to 7,500 cavities / m, less than or equal to 7,000 cavities / m, less than or equal to 6,500 cavities / m, less than or equal to 6,000 cavities / m, less than or equal to 5,500 cavities / m, less than or equal to 5,000 cavities / m, less than or equal to 4,500 cavities / m, less than or equal to 4,000 cavities / m, or less than or equal to 3,500 cavities / m. Combinations of these ranges are also possible (e.g., greater than or equal to 3000 cavities / m and less than or equal to 10000 cavities / m, greater than or equal to 3500 cavities / m and less than or equal to 10000 cavities / m, or greater than or equal to 4000 cavities / m and less than or equal to 10000 cavities / m). Other ranges are also possible.

[0037] Of course, it should be understood that the plurality of cavities from each side of the surface-treated filter medium can each independently have a transverse cavity frequency falling within one of the aforementioned ranges.

[0038] A laser system can be used to collect topographic images of the top and bottom surfaces of a surface-treated fiber web, thereby measuring the transverse cavity frequencies of the web. The transverse cavity frequencies can be estimated by dividing the number of peaks identified on the surface of the surface-treated fiber web by the linear distance scanned by the laser system. An exemplary laser system that can be used is the Mate Gauge laser system used in the following embodiments.

[0039] In some embodiments, the surface-treated fiber web advantageously has a relatively high unfolded interface area ratio. It is not desired to be bound by any particular theory, but it is believed that a surface-treated fiber web with a relatively high unfolded interface area ratio can have improved air permeability and / or dust holding capacity. In some embodiments, the unfolded interface area ratio of the surface-treated fiber web is greater than or equal to 0.1, greater than or equal to 0.12, greater than or equal to 0.15, greater than or equal to 0.18, greater than or equal to 0.2, greater than or equal to 0.3, greater than or equal to 0.5, greater than or equal to 0.8, greater than or equal to 1, greater than or equal to 1.1, greater than or equal to 1.2, greater than or equal to 1.4, greater than or equal to 1.6, greater than or equal to 1.8, greater than or equal to 2, greater than or equal to 3, greater than or equal to 4, greater than or equal to 5, greater than or equal to 8, greater than or equal to 10, greater than or equal to 15, greater than or equal to 20, greater than or equal to 30, or greater than or equal to 40. In some embodiments, the unfolded interface area ratio of the surface-treated fiber web is less than or equal to 50, less than or equal to 40, less than or equal to 30, less than or equal to 20, less than or equal to 15, less than or equal to 10, less than or equal to 8, less than or equal to 5, less than or equal to 4, less than or equal to 3, less than or equal to 2, less than or equal to 1.8, less than or equal to 1.6, less than or equal to 1.4, less than or equal to 1.2, less than or equal to 1.1, less than or equal to 1, less than or equal to 0.8, less than or equal to 0.5, less than or equal to 0.3, less than or equal to 0.2, less than or equal to 0.18, less than or equal to 0.15, or less than or equal to 0.12. Combinations of the above ranges are also possible (e.g., greater than or equal to 0.1 and less than or equal to 50, greater than or equal to 0.15 and less than or equal to 10, or greater than or equal to 0.2 and less than or equal to 5). Other ranges are also possible.

[0040] The interfacial area ratio can be determined using a scanning optical microscope, such as the Keyence VR 5000. For example, the surface morphology of a 24.1 mm × 18.1 mm sample of a surface-treated fiber web can be measured using a scanning optical microscope according to the standard described in ISO 25178 (2006). The surface morphology can be measured in pixels with a side length of 11.7 micrometers. This measurement produces a numerical matrix representing the surface height measured at a set of points on the sample, where the x and y positions of each measured surface height are given by the columns and rows of the matrix, respectively. A reference plane can then be determined according to ISO 25178 (2012). After determining the relative surface morphology, a surface shape correction can be applied to produce a corrected relative surface morphology. The correction intensity can be equal to the sample width (24.1 mm) divided by 5. Finally, the interfacial area ratio can be determined by solving the following Sdr equation:

[0041] ,

[0042] Where A is the area of ​​the sample whose surface morphology is measured, and z is the corrected relative surface height.

[0043] When the filter medium comprises two or more surface-treated fiber webs, each surface-treated fiber web may independently have an unfolded interface area ratio within one or more of the above ranges.

[0044] The surface-treated fiber web described herein can have any of a number of suitable thicknesses. In some embodiments, the thickness of the surface-treated fiber web is greater than or equal to 0.1 mm, greater than or equal to 0.15 mm, greater than or equal to 0.2 mm, greater than or equal to 0.4 mm, greater than or equal to 0.6 mm, greater than or equal to 0.8 mm, greater than or equal to 1 mm, greater than or equal to 1.5 mm, greater than or equal to 2.0 mm, greater than or equal to 2.5 mm, greater than or equal to 3.0 mm, greater than or equal to 3.5 mm, greater than or equal to 4.0 mm, greater than or equal to 4.5 mm, greater than or equal to 5.0 mm, greater than or equal to 6.0 mm, or greater than or equal to 7.0 mm. In some embodiments, the thickness of the surface-treated fiber web is less than or equal to 8.0 mm, less than or equal to 7.0 mm, less than or equal to 6.0 mm, less than or equal to 5.0 mm, less than or equal to 4.5 mm, less than or equal to 4.0 mm, less than or equal to 3.5 mm, less than or equal to 3.0 mm, less than or equal to 2.5 mm, less than or equal to 2.0 mm, less than or equal to 1.5 mm, less than or equal to 1.0 mm, less than or equal to 0.8 mm, less than or equal to 0.6 mm, less than or equal to 0.4 mm, less than or equal to 0.2 mm, or less than or equal to 0.15 mm. Combinations of these ranges are also possible (e.g., greater than or equal to 0.1 mm and less than or equal to 8.0 mm, greater than or equal to 0.1 mm and less than or equal to 5.0 mm, greater than or equal to 0.15 mm and less than or equal to 2.0 mm, or greater than or equal to 0.2 mm and less than or equal to 1.0 mm). Other ranges are also possible.

[0045] The surface-treated fiber web's weight per unit area can be determined according to ISO 534 (2011) at 2 N / cm. 2 The decision has been made.

[0046] The surface-treated fiber webs described in this article can have several suitable weights per unit area. In some embodiments, the surface-treated fiber web has a weight per unit area greater than or equal to 5 gsm, greater than or equal to 10 gsm, greater than or equal to 15 gsm, greater than or equal to 20 gsm, greater than or equal to 25 gsm, greater than or equal to 30 gsm, greater than or equal to 40 gsm, greater than or equal to 50 gsm, greater than or equal to 60 gsm, greater than or equal to 70 gsm, greater than or equal to 80 gsm, greater than or equal to 90 gsm, greater than or equal to 100 gsm, greater than or equal to 125 gsm, greater than or equal to 150 gsm, greater than or equal to 175 gsm, greater than or equal to 200 gsm, greater than or equal to 225 gsm, greater than or equal to 250 gsm, greater than or equal to 275 gsm, greater than or equal to 300 gsm, greater than or equal to 350 gsm, greater than or equal to 400 gsm, or greater than or equal to 450 gsm. In some embodiments, the surface-treated fiber web has a unit area weight of less than or equal to 500 gsm, less than or equal to 450 gsm, less than or equal to 400 gsm, less than or equal to 350 gsm, less than or equal to 300 gsm, less than or equal to 275 gsm, less than or equal to 250 gsm, less than or equal to 225 gsm, less than or equal to 200 gsm, less than or equal to 175 gsm, less than or equal to 150 gsm, less than or equal to 125 gsm, less than or equal to 100 gsm, less than or equal to 90 gsm, less than or equal to 80 gsm, less than or equal to 70 gsm, less than or equal to 60 gsm, less than or equal to 50 gsm, less than or equal to 40 gsm, less than or equal to 30 gsm, less than or equal to 25 gsm, less than or equal to 20 gsm, less than or equal to 15 gsm, or less than or equal to 10 gsm. Combinations of the above ranges are also possible (e.g., greater than or equal to 5 gsm and less than or equal to 500 gsm, greater than or equal to 10 gsm and less than or equal to 300 gsm, greater than or equal to 30 gsm and less than or equal to 200 gsm, or greater than or equal to 30 gsm and less than or equal to 100 gsm). Other ranges are also possible.

[0047] The weight per unit area of ​​surface-treated fiber webs can be determined according to ISO 536:2012.

[0048] The surface-treated fiber web described herein can have any of a number of suitable air permeability rates. In some embodiments, the surface-treated fiber web has an air permeability greater than or equal to 0.1 cfm / sf (CFM), greater than or equal to 0.2 CFM, greater than or equal to 0.5 CFM, greater than or equal to 0.75 CFM, greater than or equal to 1 CFM, greater than or equal to 2 CFM, greater than or equal to 5 CFM, greater than or equal to 7.5 CFM, greater than or equal to 10 CFM, greater than or equal to 20 CFM, greater than or equal to 50 CFM, greater than or equal to 75 CFM, greater than or equal to 100 CFM, greater than or equal to 125 CFM, greater than or equal to 150 CFM, greater than or equal to 175 CFM, greater than or equal to 200 CFM, greater than or equal to 225 CFM, greater than or equal to 250 CFM, greater than or equal to 275 CFM, greater than or equal to 300 CFM, greater than or equal to 325 CFM, greater than or equal to 350 CFM, greater than or equal to 400 CFM, greater than or equal to 500 CFM, or greater than or equal to 750 CFM. In some embodiments, the air permeability of the surface-treated fiber web is less than or equal to 1000 CFM, less than or equal to 750 CFM, less than or equal to 500 CFM, less than or equal to 400 CFM, less than or equal to 350 CFM, less than or equal to 325 CFM, less than or equal to 300 CFM, less than or equal to 275 CFM, less than or equal to 250 CFM, less than or equal to 225 CFM, less than or equal to 200 CFM, less than or equal to 175 CFM, less than or equal to 150 CFM, less than or equal to 125 CFM, less than or equal to 100 CFM, less than or equal to 75 CFM, less than or equal to 50 CFM, less than or equal to 20 CFM, less than or equal to 10 CFM, less than or equal to 7.5 CFM, less than or equal to 5 CFM, less than or equal to 2 CFM, less than or equal to 1 CFM, less than or equal to 0.75 CFM, less than or equal to 0.5 CFM, or less than or equal to 0.2 CFM. Combinations of the above ranges are also possible (e.g., greater than or equal to 0.1 CFM and less than or equal to 1000 CFM, greater than or equal to 0.1 CFM and less than or equal to 800 CFM, greater than or equal to 10 CFM and less than or equal to 500 CFM, or greater than or equal to 30 CFM and less than or equal to 400 CFM). Other ranges are also possible.

[0049] The air permeability of the surface-treated fiber web can be determined according to ASTM D737-04 (2016) at a pressure of 125 Pa.

[0050] The surface-treated fiber web described herein can have multiple suitable average flow rate apertures. The average flow rate aperture of the surface-treated fiber web can be greater than or equal to 0.1 μm, greater than or equal to 0.15 μm, greater than or equal to 0.2 μm, greater than or equal to 0.25 μm, greater than or equal to 0.3 μm, greater than or equal to 0.4 μm, greater than or equal to 0.5 μm, greater than or equal to 0.75 μm, greater than or equal to 1 μm, greater than or equal to 2 μm, greater than or equal to 5 μm, greater than or equal to 7.5 μm, greater than or equal to 10 μm, greater than or equal to 20 μm, greater than or equal to 40 μm, greater than or equal to 60 μm, greater than or equal to 80 μm, greater than or equal to 100 μm, greater than or equal to 125 μm, greater than or equal to 150 μm, or greater than or equal to 175 μm. The average flow aperture of the surface-treated fiber web can be less than or equal to 200 micrometers, less than or equal to 175 micrometers, less than or equal to 150 micrometers, less than or equal to 100 micrometers, less than or equal to 80 micrometers, less than or equal to 60 micrometers, less than or equal to 40 micrometers, less than or equal to 20 micrometers, less than or equal to 10 micrometers, less than or equal to 7.5 micrometers, less than or equal to 5 micrometers, less than or equal to 2 micrometers, less than or equal to 1 micrometer, less than or equal to 0.75 micrometers, less than or equal to 0.5 micrometers, less than or equal to 0.4 micrometers, less than or equal to 0.3 micrometers, less than or equal to 0.25 micrometers, less than or equal to 0.2 micrometers, or less than or equal to 0.15 micrometers. Combinations of the above ranges are also possible (e.g., greater than or equal to 0.1 micrometers and less than or equal to 200 micrometers, greater than or equal to 0.1 micrometers and less than or equal to 100 micrometers, greater than or equal to 1 micrometer and less than or equal to 60 micrometers, or greater than or equal to 1 micrometer and less than or equal to 40 micrometers). Other ranges are also possible.

[0051] The average flow aperture of the surface-treated fiber web can be determined according to ASTM F316 (2003).

[0052] The surface-treated fiber web described herein can have several suitable maximum pore sizes. The maximum pore size of the surface-treated fiber web can be greater than or equal to 0.1 μm, greater than or equal to 0.15 μm, greater than or equal to 0.2 μm, greater than or equal to 0.25 μm, greater than or equal to 0.3 μm, greater than or equal to 0.4 μm, greater than or equal to 0.5 μm, greater than or equal to 0.75 μm, greater than or equal to 1 μm, greater than or equal to 2 μm, greater than or equal to 5 μm, greater than or equal to 7.5 μm, greater than or equal to 10 μm, greater than or equal to 20 μm, greater than or equal to 40 μm, greater than or equal to 60 μm, greater than or equal to 80 μm, greater than or equal to 100 μm, greater than or equal to 125 μm, greater than or equal to 150 μm, greater than or equal to 175 μm, greater than or equal to 200 μm, greater than or equal to 225 μm, greater than or equal to 250 μm, or greater than or equal to 275 μm. The maximum pore size of the surface-treated fiber web can be less than or equal to 300 micrometers, less than or equal to 275 micrometers, less than or equal to 250 micrometers, less than or equal to 225 micrometers, less than or equal to 200 micrometers, less than or equal to 175 micrometers, less than or equal to 150 micrometers, less than or equal to 100 micrometers, less than or equal to 80 micrometers, less than or equal to 60 micrometers, less than or equal to 40 micrometers, less than or equal to 20 micrometers, less than or equal to 10 micrometers, less than or equal to 7.5 micrometers, less than or equal to 5 micrometers, less than or equal to 2 micrometers, less than or equal to 1 micrometer, less than or equal to 0.75 micrometers, less than or equal to 0.5 micrometers, less than or equal to 0.4 micrometers, less than or equal to 0.3 micrometers, less than or equal to 0.25 micrometers, less than or equal to 0.2 micrometers, or less than or equal to 0.15 micrometers. Combinations of the above ranges are also possible (e.g., greater than or equal to 0.1 micrometers and less than or equal to 300 micrometers, greater than or equal to 0.1 micrometers and less than or equal to 200 micrometers, or greater than or equal to 2 micrometers and less than or equal to 100 micrometers). Other ranges are also possible.

[0053] The maximum aperture of the surface-treated fiber web can be determined according to ASTM F316 (2003).

[0054] Surface-treated fiber webs can have any of a number of suitable apparent densities. The apparent density of surface-treated fiber webs can be greater than or equal to 30, greater than or equal to 40 gsm / mm, greater than or equal to 50 gsm / mm, greater than or equal to 60 gsm / mm, greater than or equal to 70 gsm / mm, greater than or equal to 80 gsm / mm, greater than or equal to 90 gsm / mm, greater than or equal to 100 gsm / mm, greater than or equal to 125 gsm / mm, greater than or equal to 150 gsm / mm, greater than or equal to 175 gsm / mm, greater than or equal to 200 gsm / mm, greater than or equal to 300 gsm / mm, or greater than or equal to 400 gsm / mm. The apparent density of the surface-treated fiber web can be less than or equal to 500 gsm / mm, less than or equal to 400 gsm / mm, less than or equal to 300 gsm / mm, less than or equal to 200 gsm / mm, less than or equal to 175 gsm / mm, less than or equal to 150 gsm / mm, less than or equal to 125 gsm / mm, less than or equal to 100 gsm / mm, less than or equal to 90 gsm / mm, less than or equal to 80 gsm / mm, less than or equal to 70 gsm / mm, less than or equal to 60 gsm / mm, less than or equal to 50 gsm / mm, or less than or equal to 40 gsm / mm. Combinations of the above ranges are also possible (e.g., greater than or equal to 30 gsm / mm and less than or equal to 500 gsm / mm, greater than or equal to 50 gsm / mm and less than or equal to 200 gsm / mm, or greater than or equal to 60 gsm / mm and less than or equal to 175 gsm / mm). Other ranges are also possible.

[0055] The apparent density of a surface-treated fiber web can be determined by dividing the density of the surface-treated fiber web by the thickness of the surface-treated fiber web.

[0056] In some embodiments, the surface-treated fiber web described herein comprises synthetic fibers (e.g., monocomponent synthetic fibers, multicomponent synthetic fibers). The synthetic fibers may include binder fibers and / or non-binder fibers. Alternatively or additionally, the surface-treated fiber web may comprise non-synthetic fibers, such as natural fibers (e.g., hardwood fibers, softwood fibers, cellulose fibers) and / or glass fibers. In some embodiments, the use of synthetic fibers in the surface-treated fiber web is particularly advantageous for use in filter media.

[0057] The surface-treated fiber web described herein may contain synthetic fibers in any of a number of suitable amounts. In some embodiments, the surface-treated fiber web contains synthetic fibers in amounts greater than or equal to 1% by weight, greater than or equal to 5% by weight, greater than or equal to 10% by weight, greater than or equal to 20% by weight, greater than or equal to 30% by weight, greater than or equal to 40% by weight, greater than or equal to 50% by weight, greater than or equal to 60% by weight, greater than or equal to 70% by weight, greater than or equal to 80% by weight, or greater than or equal to 90% by weight. In some embodiments, the surface-treated fiber web contains synthetic fibers in amounts less than or equal to 100% by weight, less than or equal to 90% by weight, less than or equal to 80% by weight, less than or equal to 70% by weight, less than or equal to 60% by weight, less than or equal to 50% by weight, less than or equal to 40% by weight, less than or equal to 30% by weight, less than or equal to 20% by weight, less than or equal to 10% by weight, or less than or equal to 5% by weight. Combinations of these ranges are also possible (e.g., greater than or equal to 1% by weight and less than or equal to 100% by weight, greater than or equal to 50% by weight and less than or equal to 100% by weight, or greater than or equal to 80% by weight and less than or equal to 100% by weight). Other ranges are also possible.

[0058] The surface-treated fiber web described herein may comprise synthetic fibers having any of a plurality of suitable diameters. In some embodiments, the surface-treated fiber web comprises synthetic fibers having the following average diameters: greater than or equal to 0.01 micrometers, greater than or equal to 0.02 micrometers, greater than or equal to 0.05 micrometers, greater than or equal to 0.1 micrometers, greater than or equal to 0.2 micrometers, greater than or equal to 0.5 micrometers, greater than or equal to 1 micrometer, greater than or equal to 2 micrometers, greater than or equal to 5 micrometers, greater than or equal to 10 micrometers, greater than or equal to 20 micrometers, greater than or equal to 30 micrometers, greater than or equal to 40 micrometers, greater than or equal to 50 micrometers, or greater than or equal to 60 micrometers, greater than or equal to 70 micrometers, or greater than or equal to 80 micrometers. In some embodiments, the surface-treated fiber web comprises synthetic fibers having the following average diameters: less than or equal to 100 micrometers, less than or equal to 90 micrometers, less than or equal to 80 micrometers, less than or equal to 70 micrometers, less than or equal to 60 micrometers, less than or equal to 50 micrometers, less than or equal to 40 micrometers, less than or equal to 30 micrometers, less than or equal to 20 micrometers, less than or equal to 10 micrometers, less than or equal to 5 micrometers, less than or equal to 2 micrometers, less than or equal to 1 micrometer, less than or equal to 0.5 micrometers, less than or equal to 0.2 micrometers, less than or equal to 0.1 micrometers, or less than or equal to 0.05 micrometers. Combinations of these ranges are also possible (e.g., greater than or equal to 0.01 micrometers and less than or equal to 100 micrometers, greater than or equal to 0.01 micrometers and less than or equal to 50 micrometers, greater than or equal to 1 micrometer and less than or equal to 20 micrometers, or greater than or equal to 5 micrometers and less than or equal to 20 micrometers). Other ranges are also possible.

[0059] The surface-treated fiber web described herein may comprise synthetic fibers having any of a plurality of suitable lengths. In some embodiments, the surface-treated fiber web comprises synthetic fibers having the following average lengths: greater than or equal to 0.1 mm, greater than or equal to 0.5 mm, greater than or equal to 1 mm, greater than or equal to 2 mm, greater than or equal to 4 mm, greater than or equal to 6 mm, greater than or equal to 8 mm, greater than or equal to 10 mm, greater than or equal to 12 mm, greater than or equal to 14 mm, greater than or equal to 16 mm, greater than or equal to 18 mm, greater than or equal to 20 mm, greater than or equal to 25 mm, greater than or equal to 30 mm, greater than or equal to 35 mm, greater than or equal to 40 mm, or greater than or equal to 45 mm. In some embodiments, the surface-treated fiber web comprises synthetic fibers having the following average lengths: less than or equal to 50 mm, less than or equal to 45 mm, less than or equal to 40 mm, less than or equal to 35 mm, less than or equal to 30 mm, less than or equal to 25 mm, less than or equal to 20 mm, less than or equal to 18 mm, less than or equal to 16 mm, less than or equal to 14 mm, less than or equal to 12 mm, less than or equal to 10 mm, less than or equal to 8 mm, less than or equal to 6 mm, less than or equal to 4 mm, less than or equal to 2 mm, less than or equal to 1 mm, or less than or equal to 0.5 mm. Combinations of these ranges are also possible (e.g., greater than or equal to 0.1 mm and less than or equal to 50 mm, greater than or equal to 0.1 mm and less than or equal to 40 mm, greater than or equal to 1 mm and less than or equal to 20 mm, or greater than or equal to 4 mm and less than or equal to 20 mm). Other ranges are also possible.

[0060] In some embodiments, the surface-treated fiber web comprises synthetic fibers that act as binder fibers. In some such embodiments, the binder fibers may comprise one type of binder fiber (e.g., monocomponent fiber, multicomponent fiber) or more than one type of binder fiber (e.g., both monocomponent and multicomponent fibers, two types of monocomponent fibers, two types of multicomponent fibers). In some such embodiments, the binder fibers may act as an adhesive for bonding the fibers within the web together in the surface-treated fiber web, as disclosed elsewhere herein.

[0061] The surface-treated fiber web described herein may contain binder fibers in any of a number of suitable amounts. In some embodiments, the surface-treated fiber web contains binder fibers in the following amounts: greater than or equal to 0 wt%, greater than or equal to 1 wt%, greater than or equal to 2 wt%, greater than or equal to 5 wt%, greater than or equal to 10 wt%, greater than or equal to 15 wt%, greater than or equal to 20 wt%, greater than or equal to 25 wt%, greater than or equal to 30 wt%, greater than or equal to 35 wt%, greater than or equal to 40 wt%, greater than or equal to 45 wt%, greater than or equal to 50 wt%, greater than or equal to 55 wt%, greater than or equal to 60 wt%, or greater than or equal to 65 wt%. In some embodiments, the surface-treated fiber web contains binder fibers in amounts of: less than or equal to 70 wt%, less than or equal to 65 wt%, less than or equal to 60 wt%, less than or equal to 55 wt%, less than or equal to 50 wt%, less than or equal to 45 wt%, less than or equal to 40 wt%, less than or equal to 35 wt%, less than or equal to 30 wt%, less than or equal to 25 wt%, less than or equal to 20 wt%, less than or equal to 15 wt%, less than or equal to 10 wt%, less than or equal to 5 wt%, less than or equal to 2 wt%, or less than or equal to 1 wt%. Combinations of these ranges are also possible (e.g., greater than or equal to 0 wt% and less than or equal to 70 wt%, greater than or equal to 0 wt% and less than or equal to 50 wt%, greater than or equal to 1 wt% and less than or equal to 30 wt%, or greater than or equal to 2 wt% and less than or equal to 30 wt%). Other ranges are also possible.

[0062] The surface-treated fiber web described herein may comprise binder fibers having any of a plurality of suitable diameters. In some embodiments, the surface-treated fiber web comprises binder fibers having the following average diameters: greater than or equal to 0.01 micrometers, greater than or equal to 0.02 micrometers, greater than or equal to 0.05 micrometers, greater than or equal to 0.1 micrometers, greater than or equal to 0.2 micrometers, greater than or equal to 0.5 micrometers, greater than or equal to 1 micrometer, greater than or equal to 2 micrometers, greater than or equal to 5 micrometers, greater than or equal to 10 micrometers, greater than or equal to 20 micrometers, greater than or equal to 30 micrometers, greater than or equal to 40 micrometers, greater than or equal to 50 micrometers, or greater than or equal to 60 micrometers, greater than or equal to 70 micrometers, or greater than or equal to 80 micrometers. In some embodiments, the surface-treated fiber web comprises binder fibers having the following average diameters: less than or equal to 100 micrometers, less than or equal to 90 micrometers, less than or equal to 80 micrometers, less than or equal to 70 micrometers, less than or equal to 60 micrometers, less than or equal to 50 micrometers, less than or equal to 40 micrometers, less than or equal to 30 micrometers, less than or equal to 20 micrometers, less than or equal to 10 micrometers, less than or equal to 5 micrometers, less than or equal to 2 micrometers, less than or equal to 1 micrometer, less than or equal to 0.5 micrometers, less than or equal to 0.2 micrometers, less than or equal to 0.1 micrometers, or less than or equal to 0.05 micrometers. Combinations of these ranges are also possible (e.g., greater than or equal to 0.01 micrometers and less than or equal to 100 micrometers, greater than or equal to 0.01 micrometers and less than or equal to 50 micrometers, greater than or equal to 1 micrometer and less than or equal to 20 micrometers, or greater than or equal to 5 micrometers and less than or equal to 20 micrometers). Other ranges are also possible.

[0063] The surface-treated fiber web described herein may comprise binder fibers having any of a plurality of suitable lengths. In some embodiments, the surface-treated fiber web comprises binder fibers having the following average lengths: greater than or equal to 0.1 mm, greater than or equal to 0.5 mm, greater than or equal to 1 mm, greater than or equal to 2 mm, greater than or equal to 4 mm, greater than or equal to 6 mm, greater than or equal to 8 mm, greater than or equal to 10 mm, greater than or equal to 12 mm, greater than or equal to 14 mm, greater than or equal to 16 mm, greater than or equal to 18 mm, greater than or equal to 20 mm, greater than or equal to 25 mm, greater than or equal to 30 mm, greater than or equal to 35 mm, greater than or equal to 40 mm, or greater than or equal to 45 mm. In some embodiments, the surface-treated fiber web comprises binder fibers having the following average lengths: less than or equal to 50 mm, less than or equal to 45 mm, less than or equal to 40 mm, less than or equal to 35 mm, less than or equal to 30 mm, less than or equal to 25 mm, less than or equal to 20 mm, less than or equal to 18 mm, less than or equal to 16 mm, less than or equal to 14 mm, less than or equal to 12 mm, less than or equal to 10 mm, less than or equal to 8 mm, less than or equal to 6 mm, less than or equal to 4 mm, less than or equal to 2 mm, less than or equal to 1 mm, or less than or equal to 0.5 mm. Combinations of these ranges are also possible (e.g., greater than or equal to 0.1 mm and less than or equal to 50 mm, greater than or equal to 0.1 mm and less than or equal to 40 mm, greater than or equal to 1 mm and less than or equal to 20 mm, or greater than or equal to 4 mm and less than or equal to 20 mm). Other ranges are also possible.

[0064] In some embodiments, the binder fiber is a multicomponent fiber. The multicomponent fiber can be a bicomponent fiber (i.e., a fiber containing two components), and / or a fiber containing three or more components. Multicomponent fibers can have a variety of suitable structures. For example, a multicomponent fiber can comprise one or more of the following types of bicomponent fibers: core / sheath fibers (e.g., concentric core / sheath fibers, non-concentric core-sheath fibers), segmented disc fibers, parallel fibers, tip-trefoil fibers, and “island” fibers. Core-sheath bicomponent fibers can comprise a sheath having a melting temperature lower than that of the core. When heated (e.g., during the bonding step), the sheath can melt before the core, thereby allowing the sheath to act as a binder. In such embodiments, the multicomponent fiber can be used as a binder for layers.

[0065] Non-limiting examples of suitable materials that can be included in multicomponent fibers include: poly(olefins), such as poly(ethylene), poly(propylene), and poly(butene); poly(esters) and copoly(esters), such as poly(ethylene terephthalate), copoly(ethylene terephthalate), poly(butylene terephthalate), and poly(ethylene isophthalate); poly(amides) and copoly(amides), such as nylon and aromatic polyamides; and halogenated polymers, such as poly(tetrafluoroethylene). Suitable copoly(ethylene terephthalate) may comprise repeating units formed by the polymerization of polyethylene terephthalate monomers, and may also comprise repeating units formed by the polymerization of one or more comonomers. Such comonomers may include linear, cyclic, and branched aliphatic dicarboxylic acids having 4 to 12 carbon atoms (e.g., succinic acid, glutaric acid, adipic acid, dodecanoic acid, and 1,4-cyclohexanedicarboxylic acid); aromatic dicarboxylic acids having 8 to 12 carbon atoms (e.g., isophthalic acid and 2,6-naphthalenedicarboxylic acid); linear, cyclic, and branched aliphatic diols having 3 to 8 carbon atoms (e.g., 1,3-propanediol, 1,2-propanediol, 1,4-butanediol, 3-methyl-1,5-pentanediol, 2,2-dimethyl-1,3-propanediol, 2-methyl-1,3-propanediol, and 1,4-cyclohexanediol); and / or aliphatic and aromatic / aliphatic ether diols having 4 to 10 carbon atoms (e.g., hydroquinone bis(2-hydroxyethyl) ethers and poly(ethylene ether) diols, such as diethylene ether diol, with a molecular weight of less than 460 g / mol). etherglycol).

[0066] The copolymer (ethylene terephthalate) can contain repeating units formed by the polymerization of comonomers (e.g., monomers other than ethylene glycol and terephthalic acid) in various suitable amounts. For example, the copolymer (ethylene terephthalate) can be formed from a mixture of monomers in which the comonomers may account for greater than or equal to 0.5 mol%, greater than or equal to 0.75 mol%, greater than or equal to 1 mol%, greater than or equal to 1.5 mol%, greater than or equal to 2 mol%, greater than or equal to 3 mol%, greater than or equal to 5 mol%, greater than or equal to 7.5 mol%, greater than or equal to 10 mol%, or greater than or equal to 12.5 mol%. The copolymer (ethylene terephthalate) can be formed from a mixture of monomers in which the comonomer comprises less than or equal to 15 mol%, less than or equal to 12.5 mol%, less than or equal to 10 mol%, less than or equal to 7.5 mol%, less than or equal to 5 mol%, less than or equal to 3 mol%, less than or equal to 2 mol%, less than or equal to 1.5 mol%, less than or equal to 1 mol%, or less than or equal to 0.75 mol%. Combinations of the above ranges are also possible (e.g., greater than or equal to 0.5 mol% and less than or equal to 15 mol%). Other ranges are also possible.

[0067] In embodiments in which the copolymer (ethylene terephthalate) comprises two or more types of repeating units formed by the polymerization of comonomers, each type of repeating unit may independently account for one or more mol% of the total amount of monomers from which it forms the copolymer (ethylene terephthalate) within the above range, and / or all comonomers together may account for one or more mol% of the total amount of monomers from which it forms the copolymer (ethylene terephthalate) within the above range.

[0068] Non-limiting examples of suitable material pairs that can be included in bicomponent fibers include poly(ethylene) / poly(ethylene terephthalate), poly(propylene) / poly(ethylene terephthalate), copolymer (ethylene terephthalate) / poly(ethylene terephthalate), poly(butylene terephthalate) / poly(ethylene terephthalate), copolymer (amide) / poly(amide), and poly(ethylene) / poly(propylene). In the preceding list, materials with lower melting temperatures are listed first, followed by materials with higher melting temperatures. A core-sheath bicomponent fiber containing one of such pairs can have a sheath comprising a first material and a core comprising a second material.

[0069] The multicomponent fibers described herein may comprise components having multiple suitable melting points. In some embodiments, the multicomponent fibers comprise components having melting points greater than or equal to 80°C, greater than or equal to 90°C, greater than or equal to 100°C, greater than or equal to 110°C, greater than or equal to 120°C, greater than or equal to 130°C, greater than or equal to 140°C, greater than or equal to 150°C, greater than or equal to 160°C, greater than or equal to 170°C, greater than or equal to 180°C, greater than or equal to 190°C, greater than or equal to 200°C, greater than or equal to 210°C, or greater than or equal to 220°C. In some embodiments, the multicomponent fiber comprises a component having a melting point of ≤230°C, ≤220°C, ≤210°C, ≤200°C, ≤190°C, ≤180°C, ≤170°C, ≤160°C, ≤150°C, ≤140°C, ≤130°C, ≤120°C, ≤110°C, ≤100°C, or ≤90°C. Combinations of the above ranges are also possible (e.g., ≥80°C and ≤230°C, or ≥110°C and ≤230°C). Other ranges are also possible. In some embodiments, the multicomponent fiber comprises a component with a melting point ≤100°C. The melting points of the components of the multicomponent fiber can be determined by differential scanning calorimetry. Differential scanning calorimetry (DSC) measurements can be performed by heating the multicomponent fiber to 300°C at 20°C / min, cooling the multicomponent fiber to room temperature, and then reheating it to 300°C at 20°C / min to determine the melting point.

[0070] In some embodiments, the surface-treated fiber web comprises synthetic fibers that are not binder fibers. Such synthetic fibers may include monocomponent synthetic fibers and / or multicomponent synthetic fibers. When present, the multicomponent synthetic fibers that are not binder fibers may have one or more of the forms described elsewhere herein with respect to multicomponent binder fibers.

[0071] Non-adhesive synthetic fibers may include a variety of materials, including but not limited to poly(esters) (e.g., polyethylene terephthalate, polybutylene terephthalate)), poly(carbonate), poly(amides) (e.g., various nylon polymers), poly(aramids), poly(imides), poly(olefins) (e.g., poly(ethylene), poly(propylene)), poly(ether ether ketones), poly(acrylic acids) (e.g., poly(acrylonitrile), dry-spun poly(acrylic acid)), poly(vinyl alcohol), regenerated cellulose (e.g., synthetic cellulose such as cellulose acetate, rayon), fluorinated polymers (e.g., poly(vinylidene fluoride) (PVDF)), copolymers of poly(ethylene) and PVDF, and poly(ether sulfone).

[0072] Unbonded synthetic fibers can comprise a variety of suitable amounts of the surface-treated fiber web described herein. In some embodiments, the unbonded synthetic fibers comprise 0% or more by weight, 1% or more by weight, 2% or more by weight, 5% or more by weight, 7.5% or more by weight, 10% or more by weight, 15% or more by weight, 20% or more by weight, 25% or more by weight, 30% or more by weight, 35% or more by weight, 40% or more by weight, 45% or more by weight, 50% or more by weight, 55% or more by weight, 60% or more by weight, 65% or more by weight, 70% or more by weight, 75% or more by weight, 80% or more by weight, or 90% or more by weight of the surface-treated fiber web. In some embodiments, the non-adhesive synthetic fiber comprises less than or equal to 95% by weight, less than or equal to 90% by weight, less than or equal to 85% by weight, less than or equal to 80% by weight, less than or equal to 75% by weight, less than or equal to 70% by weight, less than or equal to 65% by weight, less than or equal to 60% by weight, less than or equal to 55% by weight, less than or equal to 50% by weight, less than or equal to 45% by weight, less than or equal to 40% by weight, less than or equal to 35% by weight, less than or equal to 30% by weight, less than or equal to 25% by weight, less than or equal to 20% by weight, less than or equal to 15% by weight, less than or equal to 10% by weight, less than or equal to 7.5% by weight, less than or equal to 5% by weight, less than or equal to 2% by weight, or less than or equal to 1% by weight. Combinations of the above ranges are also possible (e.g., greater than or equal to 0% by weight and less than or equal to 95% by weight, greater than or equal to 5% by weight and less than or equal to 80% by weight, or greater than or equal to 10% by weight and less than or equal to 70% by weight). Other ranges are also possible.

[0073] When a surface-treated fiber web comprises two or more types of non-adhesive synthetic fibers, each type of non-adhesive synthetic fiber may independently constitute an amount within one or more of the aforementioned ranges of the surface-treated fiber web, and / or all non-adhesive synthetic fibers in the surface-treated fiber web may together constitute an amount within one or more of the aforementioned ranges of the surface-treated fiber web. Similarly, when a filter medium comprises two or more surface-treated fiber webs, each surface-treated fiber web may independently contain an amount of any particular type of non-adhesive synthetic fiber within one or more of the aforementioned ranges, and / or may contain a total amount of non-adhesive synthetic fibers within one or more of the aforementioned ranges.

[0074] The non-binder synthetic fibers present in the surface-treated fiber web can have multiple suitable average fiber diameters. In some embodiments, the surface-treated fiber web comprises non-binder synthetic fibers having the following average fiber diameters: greater than or equal to 0.01 micrometers, greater than or equal to 0.02 micrometers, greater than or equal to 0.05 micrometers, greater than or equal to 0.1 micrometers, greater than or equal to 0.2 micrometers, greater than or equal to 0.5 micrometers, greater than or equal to 1 micrometer, greater than or equal to 1.5 micrometers, greater than or equal to 2 micrometers, greater than or equal to 2.5 micrometers, greater than or equal to 3 micrometers, greater than or equal to 5 micrometers, greater than or equal to 10 micrometers, greater than or equal to 15 micrometers, greater than or equal to 20 micrometers, greater than or equal to 25 micrometers, greater than or equal to 30 micrometers, greater than or equal to 35 micrometers, greater than or equal to 40 micrometers, greater than or equal to 45 micrometers, greater than or equal to 50 micrometers, greater than or equal to 55 micrometers, greater than or equal to 60 micrometers, greater than or equal to 65 micrometers, greater than or equal to 70 micrometers, greater than or equal to 75 micrometers, greater than or equal to 80 micrometers, greater than or equal to 85 micrometers, greater than or equal to 90 micrometers, or greater than or equal to 95 micrometers. In some embodiments, the surface-treated fiber web comprises non-binder synthetic fibers having the following average fiber diameters: less than or equal to 100 micrometers, less than or equal to 95 micrometers, less than or equal to 90 micrometers, less than or equal to 85 micrometers, less than or equal to 80 micrometers, less than or equal to 75 micrometers, less than or equal to 70 micrometers, less than or equal to 65 micrometers, less than or equal to 60 micrometers, less than or equal to 55 micrometers, less than or equal to 50 micrometers, less than or equal to 45 micrometers, less than or equal to 40 micrometers, less than or equal to 35 micrometers, less than or equal to 30 micrometers, less than or equal to 25 micrometers, less than or equal to 20 micrometers, less than or equal to 15 micrometers, less than or equal to 10 micrometers, less than or equal to 5 micrometers, less than or equal to 3 micrometers, less than or equal to 2.5 micrometers, less than or equal to 2 micrometers, less than or equal to 1.5 micrometers, less than or equal to 1 micrometer, less than or equal to 0.5 micrometers, less than or equal to 0.2 micrometers, less than or equal to 0.1 micrometers, less than or equal to 0.05 micrometers, or less than or equal to 0.02 micrometers. Combinations of the above ranges are also possible (e.g., greater than or equal to 0.01 micrometers and less than or equal to 100 micrometers, greater than or equal to 0.1 micrometers and less than or equal to 100 micrometers, greater than or equal to 0.5 micrometers and less than or equal to 50 micrometers, or greater than or equal to 2 micrometers and less than or equal to 20 micrometers). Other ranges are also possible.

[0075] When the surface-treated fiber web comprises two or more types of non-adhesive synthetic fibers, each type of non-adhesive synthetic fiber may independently have an average fiber diameter within one or more of the aforementioned ranges, and / or all non-adhesive synthetic fibers in the surface-treated fiber web may collectively have an average fiber diameter within one or more of the aforementioned ranges. Similarly, when the filter media comprises two or more surface-treated fiber webs, each surface-treated fiber web may independently contain one or more types of non-adhesive synthetic fibers with an average fiber diameter within one or more of the aforementioned ranges, and / or may contain non-adhesive synthetic fibers that collectively have an average fiber diameter within one or more of the aforementioned ranges.

[0076] The unbonded synthetic fibers present in the surface-treated fiber web can have several suitable average fiber lengths. In some embodiments, the surface-treated fiber web comprises unbonded synthetic fibers having the following average lengths: greater than or equal to 0.1 mm, greater than or equal to 0.5 mm, greater than or equal to 1 mm, greater than or equal to 2 mm, greater than or equal to 4 mm, greater than or equal to 6 mm, greater than or equal to 8 mm, greater than or equal to 10 mm, greater than or equal to 12 mm, greater than or equal to 14 mm, greater than or equal to 16 mm, greater than or equal to 18 mm, greater than or equal to 20 mm, greater than or equal to 25 mm, greater than or equal to 30 mm, greater than or equal to 35 mm, greater than or equal to 40 mm, or greater than or equal to 45 mm. In some embodiments, the surface-treated fiber web comprises unbonded synthetic fibers having the following average lengths: less than or equal to 50 mm, less than or equal to 45 mm, less than or equal to 40 mm, less than or equal to 35 mm, less than or equal to 30 mm, less than or equal to 25 mm, less than or equal to 20 mm, less than or equal to 18 mm, less than or equal to 16 mm, less than or equal to 14 mm, less than or equal to 12 mm, less than or equal to 10 mm, less than or equal to 8 mm, less than or equal to 6 mm, less than or equal to 4 mm, less than or equal to 2 mm, less than or equal to 1 mm, or less than or equal to 0.5 mm. Combinations of these ranges are also possible (e.g., greater than or equal to 0.1 mm and less than or equal to 50 mm, greater than or equal to 0.1 mm and less than or equal to 40 mm, greater than or equal to 1 mm and less than or equal to 20 mm, or greater than or equal to 4 mm and less than or equal to 20 mm). Other ranges are also possible.

[0077] When the surface-treated fiber web comprises two or more types of non-adhesive synthetic fibers, each type of non-adhesive synthetic fiber may independently have an average fiber length within one or more of the aforementioned ranges, and / or all non-adhesive synthetic fibers in the surface-treated fiber web may collectively have an average fiber length within one or more of the aforementioned ranges. Similarly, when the filter media comprises two or more surface-treated fiber webs, each surface-treated fiber web may independently contain one or more types of non-adhesive synthetic fibers with an average fiber length within one or more of the aforementioned ranges, and / or may contain non-adhesive synthetic fibers that collectively have an average fiber length within one or more of the aforementioned ranges.

[0078] In some embodiments, the surface-treated fiber web described herein may contain a binder resin. In some embodiments, the binder resin constitutes 0% or more by weight, 1% or more by weight, 2% or more by weight, 3% or more by weight, 5% or more by weight, 7.5% or more by weight, 10% or more by weight, 12.5% ​​or more by weight, 15% or more by weight, 17.5% or more by weight, 20% or more by weight, 25% or more by weight, 30% or more by weight, or 35% or more by weight of the surface-treated fiber web. In some embodiments, the binder resin constitutes 40% or more by weight, 35% or more by weight, 25% or more by weight, 20% or more by weight, 17.5% or more by weight, 15% or more by weight, 12.5% ​​or more by weight, 10% or more by weight, 7.5% or more by weight, 5% or more by weight, 3% or more by weight, 2% or more by weight, or 1% or more by weight of the surface-treated fiber web. Combinations of the above ranges are also possible (e.g., greater than or equal to 0% by weight and less than or equal to 40% by weight, greater than or equal to 1% by weight and less than or equal to 30% by weight, or greater than or equal to 1% by weight and less than or equal to 20% by weight). Other ranges are also possible. In some embodiments, the binder resin comprises exactly 0% by weight of the surface-treated fiber web.

[0079] When the surface-treated fiber web contains two or more types of binder resin, each type of binder resin may independently constitute an amount within one or more of the above-mentioned ranges of the surface-treated fiber web, and / or all the binder resins in the surface-treated fiber web may together constitute an amount within one or more of the above-mentioned ranges of the surface-treated fiber web. Similarly, when the filter media comprises two or more surface-treated fiber webs, each surface-treated fiber web may independently contain an amount of any particular type of binder resin within one or more of the above-mentioned ranges and / or may contain a total amount of binder resin within one or more of the above-mentioned ranges.

[0080] Binder resins can have a variety of suitable compositions. For example, in one set of embodiments, the filter media may comprise a binder resin containing thermoplastic polymers (e.g., acrylics, polyvinyl acetate, polyesters, polyamides, polycarboxylic acids, nylon, etc.), thermosetting polymers (e.g., epoxy resins, phenolic resins, melamine, etc.), or combinations thereof. In some embodiments, the binder resin includes one or more of vinyl acetate resins and polyvinyl alcohol resins. In some embodiments, the binder resin is provided in powder form. In some embodiments, the surface-treated fiber web comprises binder powder. Non-limiting examples of suitable powders include phenolic binder powder, epoxy binder powder, copolyester binder powder, and nylon binder powder.

[0081] In another aspect, a filter medium comprising a plurality of adsorbent particles is provided. As described above, the adsorbent particles may be at least partially disposed on a surface-treated fiber mesh. In some embodiments, the adsorbent particles are at least partially disposed within the cavities of a plurality of cavities, as referred to above. Figure 2 As discussed above, in some embodiments, adsorbent particles form a layer (e.g., a second layer) on a surface-treated fiber web. However, this is not necessary, and the adsorbent particles are often preferentially distributed within the cavities of the surface-treated fiber web. In some embodiments, the nonwoven fiber web contains adsorbent particles within the nonwoven fiber web (e.g., mixed between the fibers of the nonwoven fiber web).

[0082] The filter media described herein may contain adsorbent particles having any of a plurality of suitable weights per unit area. In some embodiments, the filter media contains adsorbent particles having the following weights per unit area: greater than or equal to 20 gsm, greater than or equal to 40 gsm, greater than or equal to 60 gsm, greater than or equal to 80 gsm, greater than or equal to 100 gsm, greater than or equal to 150 gsm, greater than or equal to 200 gsm, greater than or equal to 250 gsm, greater than or equal to 300 gsm, greater than or equal to 350 gsm, greater than or equal to 400 gsm, greater than or equal to 450 gsm, greater than or equal to 500 gsm, greater than or equal to 600 gsm, greater than or equal to 700 gsm, greater than or equal to 800 gsm, greater than or equal to 900 gsm, greater than or equal to 1000 gsm, or greater than or equal to 1100 gsm. In some embodiments, the filter medium comprises adsorbent particles having the following unit area weights: less than or equal to 1200 gsm, less than or equal to 1100 gsm, less than or equal to 1000 gsm, less than or equal to 900 gsm, less than or equal to 800 gsm, less than or equal to 700 gsm, less than or equal to 600 gsm, less than or equal to 500 gsm, less than or equal to 450 gsm, less than or equal to 400 gsm, less than or equal to 350 gsm, less than or equal to 300 gsm, less than or equal to 250 gsm, less than or equal to 200 gsm, less than or equal to 150 gsm, less than or equal to 100 gsm, less than or equal to 80 gsm, less than or equal to 60 gsm, or less than or equal to 40 gsm. Combinations of these ranges are also possible (e.g., greater than or equal to 20 gsm and less than or equal to 1200 gsm, greater than or equal to 20 gsm and less than or equal to 1000 gsm, greater than or equal to 40 gsm and less than or equal to 500 gsm, or greater than or equal to 40 gsm and less than or equal to 300 gsm). Other ranges are also possible.

[0083] The filter media described herein may contain adsorbent particles in any of a number of suitable proportions relative to the total weight of the filter media. In some embodiments, the filter media contains adsorbent particles in the following amounts: greater than or equal to 1% by weight, greater than or equal to 2% by weight, greater than or equal to 5% by weight, greater than or equal to 10% by weight, greater than or equal to 20% by weight, greater than or equal to 30% by weight, greater than or equal to 40% by weight, greater than or equal to 50% by weight, greater than or equal to 60% by weight, greater than or equal to 70% by weight, greater than or equal to 80% by weight, greater than or equal to 90% by weight, greater than or equal to 95% by weight, or greater than or equal to 98% by weight. In some embodiments, the filter media contains adsorbent particles in amounts of: less than or equal to 99 wt%, less than or equal to 98 wt%, less than or equal to 95 wt%, less than or equal to 90 wt%, less than or equal to 80 wt%, less than or equal to 70 wt%, less than or equal to 60 wt%, less than or equal to 50 wt%, less than or equal to 40 wt%, less than or equal to 30 wt%, less than or equal to 20 wt%, less than or equal to 10 wt%, less than or equal to 5 wt%, or less than or equal to 2 wt%. Combinations of these ranges are also possible (e.g., greater than or equal to 1 wt% and less than or equal to 99 wt%, greater than or equal to 10 wt% and less than or equal to 90 wt%, or greater than or equal to 40 wt% and less than or equal to 80 wt%). Other ranges are also possible.

[0084] The filter media described herein may comprise adsorbent particles having any of a plurality of suitable diameters. In some embodiments, the filter media comprises adsorbent particles having the following average diameters: greater than or equal to 1 micrometer, greater than or equal to 2 micrometers, greater than or equal to 3 micrometers, greater than or equal to 4 micrometers, greater than or equal to 5 micrometers, greater than or equal to 6 micrometers, greater than or equal to 7 micrometers, greater than or equal to 8 micrometers, greater than or equal to 9 micrometers, greater than or equal to 10 micrometers, greater than or equal to 20 micrometers, greater than or equal to 30 micrometers, greater than or equal to 40 micrometers, greater than or equal to 50 micrometers, greater than or equal to 80 micrometers, greater than or equal to 100 micrometers, greater than or equal to 150 micrometers, greater than or equal to 200 micrometers, greater than... Or equal to 250 micrometers, greater than or equal to 300 micrometers, greater than or equal to 350 micrometers, greater than or equal to 400 micrometers, greater than or equal to 450 micrometers, greater than or equal to 500 micrometers, greater than or equal to 600 micrometers, greater than or equal to 700 micrometers, greater than or equal to 800 micrometers, greater than or equal to 900 micrometers, greater than or equal to 1000 micrometers, greater than or equal to 1500 micrometers, greater than or equal to 2000 micrometers, greater than or equal to 2500 micrometers, greater than or equal to 3000 micrometers, greater than or equal to 3500 micrometers, greater than or equal to 4000 micrometers, or greater than or equal to 4500 micrometers. In some embodiments, the filter medium comprises adsorbent particles having the following average diameters: less than or equal to 5000 micrometers, less than or equal to 4500 micrometers, less than or equal to 4000 micrometers, less than or equal to 3500 micrometers, less than or equal to 3000 micrometers, less than or equal to 2500 micrometers, less than or equal to 2000 micrometers, less than or equal to 1500 micrometers, less than or equal to 1000 micrometers, less than or equal to 900 micrometers, less than or equal to 800 micrometers, less than or equal to 700 micrometers, less than or equal to 600 micrometers, less than or equal to 500 micrometers, less than or equal to 450 micrometers, less than or equal to... The ranges are 400 micrometers or less, 350 micrometers or less, 300 micrometers or less, 250 micrometers or less, 200 micrometers or less, 150 micrometers or less, 100 micrometers or less, 80 micrometers or less, 50 micrometers or less, 40 micrometers or less, 30 micrometers or less, 20 micrometers or less, 10 micrometers or less, 9 micrometers or less, 8 micrometers or less, 7 micrometers or less, 6 micrometers or less, 5 micrometers or less, 4 micrometers or less, 3 micrometers or less, or 2 micrometers or less. Combinations of these ranges are also possible (e.g., greater than or equal to 1 micrometer and less than or equal to 5000 micrometers, greater than or equal to 5 micrometers and less than or equal to 800 micrometers, or greater than or equal to 5 micrometers and less than or equal to 200 micrometers). Other ranges are also possible.

[0085] Adsorbent particles used as filter media can have any of a variety of suitable compositions and properties. For example, in some embodiments, the adsorbent particles are conductive particles. As another example, in some embodiments, the adsorbent particles are capacitive particles. The representative properties and compositions of various adsorbent particles are discussed in more detail below.

[0086] Any of a variety of adsorbent conductive particles can be used. In some embodiments, the conductive particles comprise a carbon-containing material. The carbon-containing material may include carbon black, acetylene black, graphite, graphene, and / or carbon nanotubes. The conductive particles may contain one or more of the above materials throughout the particle (e.g., the particles may be formed from one or more of the above materials), or may contain one or more of the above materials as a coating (e.g., on a core with a different composition).

[0087] When present, conductive particles can have any suitable average conductivity. The average conductivity of conductive particles can be greater than or equal to 1 S / m, greater than or equal to 2 S / m, greater than or equal to 5 S / m, greater than or equal to 10 S / m, greater than or equal to 20 S / m, greater than or equal to 50 S / m, greater than or equal to 100 S / m, greater than or equal to 200 S / m, greater than or equal to 500 S / m, greater than or equal to 1,000 S / m, greater than or equal to 2,000 S / m, greater than or equal to 5,000 S / m, greater than or equal to 10,000 S / m, greater than or equal to 200,000 S / m, or greater than or equal to 250,000 S / m. The average conductivity of the conductive particles can be less than or equal to 300,000 S / m, less than or equal to 250,000 S / m, less than or equal to 200,000 S / m, less than or equal to 100,000 S / m, less than or equal to 50,000 S / m, less than or equal to 20,000 S / m, less than or equal to 10,000 S / m, less than or equal to 5,000 S / m, less than or equal to 2,000 S / m, less than or equal to 1,000 S / m, less than or equal to 500 S / m, less than or equal to 200 S / m, less than or equal to 100 S / m, less than or equal to 50 S / m, less than or equal to 20 S / m, less than or equal to 10 S / m, less than or equal to 5 S / m, or less than or equal to 2 S / m. Combinations of the above ranges are also possible (e.g., greater than or equal to 1 S / m and less than or equal to 300,000 S / m, greater than or equal to 5 S / m and less than or equal to 250,000 S / m, or greater than or equal to 10 S / m and less than or equal to 200,000 S / m). Other ranges are also possible.

[0088] The average conductivity of conductive particles can be determined by applying 500 psi. 2 The pressure is used to compress conductive particles into pellets of known length and cross-sectional area. A voltage is applied across the pellets, and the current across the pellets is measured. The voltage is divided by the current to determine the resistance of the pellets, and then the reciprocal of the resistance is divided by the ratio of the cross-sectional area of ​​the pellets to the length of the pellets.

[0089] Any of a variety of adsorption capacitive particles can be used. In some embodiments, the capacitive particles comprise a carbon-containing material. The carbon-containing material may include activated carbon. The capacitive particles may contain one or more of the above-mentioned materials throughout the particle (e.g., the particles may be formed from one or more of the above-mentioned materials), or may contain one or more of the above-mentioned materials as a coating (e.g., on a core of different compositions).

[0090] When present, capacitive particles can have any suitable average specific capacitance. The average specific capacitance of capacitive particles can be greater than or equal to 1 F / g, greater than or equal to 2 F / g, greater than or equal to 5 F / g, greater than or equal to 10 F / g, greater than or equal to 20 F / g, greater than or equal to 50 F / g, greater than or equal to 100 F / g, greater than or equal to 200 F / g, greater than or equal to 250 F / g, or greater than or equal to 400 F / g. The average specific capacitance of capacitive particles can be less than or equal to 500 F / g, less than or equal to 400 F / g, less than or equal to 250 F / g, less than or equal to 200 F / g, less than or equal to 100 F / g, less than or equal to 50 F / g, less than or equal to 20 F / g, less than or equal to 10 F / g, less than or equal to 5 F / g, or less than or equal to 2 F / g. Combinations of the above ranges are also possible (e.g., greater than or equal to 1 F / g and less than or equal to 500 F / g, greater than or equal to 10 F / g and less than or equal to 250 F / g, or greater than or equal to 20 F / g and less than or equal to 200 F / g). Other ranges are also possible.

[0091] The average specific capacitance of the capacitive particles can be determined according to IEC 62576:2018. In short, the method includes: (1) constructing a symmetrical supercapacitor / supercapacitor device comprising two identical electrodes containing capacitive particles, a separator, and 1.28 spg of sulfuric acid electrolyte; (2) measuring the voltage as a function of time during a constant current charge-discharge test across a voltage varying from 0 V to 1 V; (3) identifying time periods in which the voltage decreases linearly with time; (4) multiplying the slope of the voltage decrease as a function of time during these time periods by the discharge current to determine the capacitance of the particles; and (5) multiplying the measured particle capacitance by 4 and dividing the value by the mass of the active material in each electrode. The same electrode containing capacitive particles can be formed and prepared for use in a symmetrical supercapacitor / supercapacitor device by means of: (1) mixing capacitive particles and carbon black particles with an average diameter of 200 nm together at a weight ratio of 18:1; (2) dispersing 60% by weight of PTFE solids in water (average solid diameter 50 nm; dispersion density 1.50 g / cm³). 3 (2) Dilute to form a dispersion of 5% by weight PTFE solids in water; (3) Mix the 5% by weight PTFE dispersion with a mixture of capacitive particles and carbon black particles to form an electrode precursor with a capacitive particle:carbon black particle:PTFE ratio of 90:5:5; (4) Roll-press the electrode precursor to form a thickness of 150 micrometers and a density of 1 mg / mm. 3 (5) Dry the electrode precursor layer in an oven at 75°C for 12 hours; (6) Cut a 4 cm × 4 cm square electrode from the dried electrode precursor; and (7) Attach 316 stainless steel plates with a thickness of 0.018 cm to the square electrode.

[0092] In some implementations, the filter medium, as described herein, may comprise both a plurality of conductive adsorbent particles and a plurality of capacitive adsorbent particles.

[0093] In some embodiments, the surface-treated fiber web (e.g., a backing) contains adsorbent particles. In some embodiments, an additional layer (e.g., a layer disposed on the surface-treated fiber web, a separate layer of the capacitor layer) or a separate layer (e.g., a separate layer of the capacitor layer) contains adsorbent particles. In some embodiments, the adsorbent particles form an adsorbent particle layer that is at least partially disposed on the surface-treated fiber web as described above.

[0094] As referenced above Figures 3A to 3BAs discussed, in some embodiments, the filter medium includes one or more additional layers besides the surface-treated fiber web (e.g., backing layer) and / or adsorbent particle layer described above. Non-limiting examples of suitable additional layers include pre-filter layers and protective layers. In some embodiments, the filter medium includes an additional layer of sparse fabric (e.g., a pre-filter layer also of sparse fabric, and a protective layer also of sparse fabric). The additional layer can be attached to another layer in the fiber web (e.g., a backing layer, another additional layer) in various suitable ways (e.g., by adhesive, by using a calender, and / or by ultrasonic bonding). Other possible additional layers include: backing layers, charged layers, uncharged layers, wet-laid layers, dry-laid layers, support layers, or spacer layers. The additional layer can be produced by any of a variety of suitable methods. For example, the additional layer can be wet-laid, dry-laid, spunbond, or meltblown. Additional layers can be formed directly on top of another layer (e.g., on a surface-treated fiber web layer), or they can be formed separately and then laminated together with another layer.

[0095] When present, additional layers can possess a wide variety of properties. In some embodiments, the additional layers do not significantly contribute to the filtration performance of the filter media. In other embodiments, the additional layers contribute to one or more properties of the filter media. For example, the additional layer can serve as a pre-filter layer. As another example, a relatively large percentage of the total pressure drop across the filter media can occur across the additional layers. This can be advantageous when one or more of the other layers in the filter media are relatively fragile and / or may not be able to withstand large pressure drops.

[0096] It should be understood that any single additional layer may independently have some or all of the characteristics described below regarding additional layers. It should also be understood that the filter medium may comprise two identical additional layers and / or may comprise two or more additional layers that differ in one or more respects.

[0097] When present, additional layers may include nonwoven fiber webs comprising a plurality of fibers. A variety of suitable types of nonwoven fiber webs can be used as additional layers in the filter media described herein. For example, the filter media may include additional layers comprising wet-laid nonwoven fiber webs, non-wet-laid nonwoven fiber webs (e.g., such as meltblown nonwoven fiber webs, air-laid nonwoven fiber webs, carded nonwoven fiber webs, spunbond nonwoven fiber webs), electrospun nonwoven fiber webs, loosely woven fabrics, and / or other types of nonwoven fiber webs.

[0098] In implementations with more than one additional layer, each additional layer may independently be one or more of the types described above.

[0099] When present, the additional layer may comprise a plurality of fibers including various suitable types of fibers. In some embodiments, the additional layer comprises a plurality of fibers containing synthetic fibers and / or is made of synthetic fibers (in other words, it may be a synthetic layer). The synthetic fibers may be any of the types and compositions mentioned elsewhere herein (e.g., the synthetic fibers may be adhesive fibers or non-adhesive synthetic fibers).

[0100] In some embodiments, an additional layer comprises a plurality of fibers, including natural fibers (e.g., hardwood fibers, softwood fibers, cellulose fibers) and / or regenerated cellulose fibers. For example, the cellulose fibers may be hardwood fibers or softwood fibers. Cellulose fibers can be other than natural cellulose fibers. As an example, cellulose fibers may include regenerated cellulose and / or synthetic cellulose, such as rayon, lyocell, and celluloid. As another example, cellulose fibers include natural cellulose derivatives, such as cellulose acetate and carboxymethyl cellulose. When present, cellulose fibers may include fibrillated cellulose fibers and / or may include non-fibrillated cellulose fibers. In some embodiments, an additional layer comprises glass fibers.

[0101] The additional layers may contain more than one type of fiber (e.g., binder fibers and non-binder synthetic fibers), or may contain only one type of fiber.

[0102] When an additional layer comprises a plurality of fibers containing synthetic fibers (e.g., adhesive fibers), the additional layer may have any suitable amount of synthetic fibers. For example, in some embodiments, the synthetic fibers (e.g., adhesive fibers) are present in the additional layer in amounts relative to the total weight of the additional layer, such as: greater than or equal to 0% by weight, greater than or equal to 1% by weight, greater than or equal to 2% by weight, greater than or equal to 5% by weight, greater than or equal to 10% by weight, greater than or equal to 20% by weight, greater than or equal to 30% by weight, greater than or equal to 40% by weight, greater than or equal to 50% by weight, greater than or equal to 60% by weight, greater than or equal to 70% by weight, greater than or equal to 80% by weight, or greater than or equal to 90% by weight. In some embodiments, synthetic fibers (e.g., binder fibers) are present in the other layers in amounts relative to the total weight of the other layers: less than or equal to 100% by weight, less than or equal to 90% by weight, less than or equal to 80% by weight, less than or equal to 70% by weight, less than or equal to 60% by weight, less than or equal to 50% by weight, less than or equal to 40% by weight, less than or equal to 30% by weight, less than or equal to 20% by weight, less than or equal to 10% by weight, less than or equal to 5% by weight, less than or equal to 2% by weight, or less than or equal to 1% by weight. Combinations of the above ranges are also possible (e.g., greater than or equal to 0% by weight and less than or equal to 100% by weight, greater than or equal to 1% by weight and less than or equal to 100% by weight, greater than or equal to 50% by weight and less than or equal to 100% by weight, greater than or equal to 1% by weight and less than or equal to 30%, or greater than or equal to 80% by weight and less than or equal to 100% by weight). Other ranges are also possible. In some embodiments, synthetic fibers may be present in the other layers in an amount of 100% by weight relative to the total weight of the other layers and / or relative to the total weight of the fibers in the other layers. When present, various types of synthetic fibers (e.g., binder fibers, non-binder synthetic fibers) may each be included individually in a weight percentage falling within the aforementioned range.

[0103] When present, the additional layer can have any suitable average fiber diameter, regardless of the type of fiber present. For example, in some embodiments, the average fiber diameter of the additional layer is greater than or equal to 0.01 micrometers, greater than or equal to 0.05 micrometers, greater than or equal to 0.075 micrometers, greater than or equal to 0.1 micrometers, greater than or equal to 0.125 micrometers, greater than or equal to 0.15 micrometers, greater than or equal to 0.2 micrometers, greater than or equal to 0.25 micrometers, greater than or equal to 0.3 micrometers, greater than or equal to 0.4 micrometers, greater than or equal to 0.5 micrometers, greater than or equal to 0.75 micrometers, greater than or equal to 1 micrometer, greater than or equal to 1... 25 micrometers, greater than or equal to 1.5 micrometers, greater than or equal to 2 micrometers, greater than or equal to 2.5 micrometers, greater than or equal to 3 micrometers, greater than or equal to 4 micrometers, greater than or equal to 5 micrometers, greater than or equal to 7.5 micrometers, greater than or equal to 10 micrometers, greater than or equal to 12.5 micrometers, greater than or equal to 15 micrometers, greater than or equal to 17 micrometers, greater than or equal to 20 micrometers, greater than or equal to 25 micrometers, greater than or equal to 30 micrometers, greater than or equal to 35 micrometers, greater than or equal to 40 micrometers, or greater than or equal to 45 micrometers. In some embodiments, the average fiber diameter of the additional layers is less than or equal to 100 micrometers, less than or equal to 90 micrometers, less than or equal to 80 micrometers, less than or equal to 70 micrometers, less than or equal to 60 micrometers, less than or equal to 50 micrometers, less than or equal to 45 micrometers, less than or equal to 40 micrometers, less than or equal to 35 micrometers, less than or equal to 30 micrometers, less than or equal to 25 micrometers, less than or equal to 20 micrometers, less than or equal to 15 micrometers, less than or equal to 12.5 micrometers, less than or equal to 10 micrometers, less than or equal to 7.5 micrometers, or less than or equal to 5 micrometers. The diameter can be 1 meter, less than or equal to 4 micrometers, less than or equal to 3 micrometers, less than or equal to 2.5 micrometers, less than or equal to 2 micrometers, less than or equal to 1.5 micrometers, less than or equal to 1.25 micrometers, less than or equal to 1 micrometer, less than or equal to 0.75 micrometers, less than or equal to 0.5 micrometers, less than or equal to 0.4 micrometers, less than or equal to 0.3 micrometers, less than or equal to 0.25 micrometers, less than or equal to 0.2 micrometers, less than or equal to 0.15 micrometers, less than or equal to 0.125 micrometers, less than or equal to 0.1 micrometers, or less than or equal to 0.075 micrometers. Combinations of the above ranges are also possible (e.g., greater than or equal to 0.01 micrometers and less than or equal to 100 micrometers, greater than or equal to 0.1 micrometers and less than or equal to 75 micrometers, or greater than or equal to 0.5 micrometers and less than or equal to 25 micrometers). Other ranges are also possible. The average diameter can be determined by scanning electron microscopy.

[0104] When an additional layer comprises a plurality of fibers containing synthetic fibers, the synthetic fibers (e.g., binder fibers) may have multiple average diameters. In some embodiments, the additional layer comprises synthetic fibers (e.g., binder fibers) having the following average diameters: greater than or equal to 0.01 micrometers, greater than or equal to 0.05 micrometers, greater than or equal to 0.075 micrometers, greater than or equal to 0.1 micrometers, greater than or equal to 0.125 micrometers, greater than or equal to 0.15 micrometers, greater than or equal to 0.2 micrometers, greater than or equal to 0.25 micrometers, greater than or equal to 0.3 micrometers, greater than or equal to 0.4 micrometers, greater than or equal to 0.5 micrometers, greater than or equal to 0.75 micrometers, greater than or equal to 1 micrometer... Meter, greater than or equal to 1.25 micrometers, greater than or equal to 1.5 micrometers, greater than or equal to 2 micrometers, greater than or equal to 2.5 micrometers, greater than or equal to 3 micrometers, greater than or equal to 4 micrometers, greater than or equal to 5 micrometers, greater than or equal to 7.5 micrometers, greater than or equal to 10 micrometers, greater than or equal to 12.5 micrometers, greater than or equal to 15 micrometers, greater than or equal to 17 micrometers, greater than or equal to 20 micrometers, greater than or equal to 25 micrometers, greater than or equal to 30 micrometers, greater than or equal to 35 micrometers, greater than or equal to 40 micrometers, or greater than or equal to 45 micrometers. In some embodiments, the additional layer comprises synthetic fibers (e.g., binder fibers) having the following average diameters: less than or equal to 100 micrometers, less than or equal to 90 micrometers, less than or equal to 80 micrometers, less than or equal to 70 micrometers, less than or equal to 60 micrometers, less than or equal to 50 micrometers, less than or equal to 45 micrometers, less than or equal to 40 micrometers, less than or equal to 35 micrometers, less than or equal to 30 micrometers, less than or equal to 25 micrometers, less than or equal to 20 micrometers, less than or equal to 15 micrometers, less than or equal to 12.5 micrometers, less than or equal to 10 micrometers, and less than or equal to 7.5 micrometers. Micrometer, less than or equal to 5 micrometers, less than or equal to 4 micrometers, less than or equal to 3 micrometers, less than or equal to 2.5 micrometers, less than or equal to 2 micrometers, less than or equal to 1.5 micrometers, less than or equal to 1.25 micrometers, less than or equal to 1 micrometer, less than or equal to 0.75 micrometers, less than or equal to 0.5 micrometers, less than or equal to 0.4 micrometers, less than or equal to 0.3 micrometers, less than or equal to 0.25 micrometers, less than or equal to 0.2 micrometers, less than or equal to 0.15 micrometers, less than or equal to 0.125 micrometers, less than or equal to 0.1 micrometers, or less than or equal to 0.075 micrometers.Combinations of the above ranges are also possible (e.g., greater than or equal to 0.01 μm and less than or equal to 100 μm, greater than or equal to 0.01 μm and less than or equal to 50 μm, greater than or equal to 0.1 μm and less than or equal to 20 μm, greater than or equal to 1 μm and less than or equal to 20 μm, greater than or equal to 10 μm and less than or equal to 60 μm, greater than or equal to 17 μm and less than or equal to 35 μm, greater than or equal to 0.05 μm and less than or equal to 50 μm, greater than or equal to 0.05 μm and less than or equal to 30 μm, greater than or equal to 0.05 μm and less than or equal to 5 μm, greater than or equal to 0.05 μm and less than or equal to 2 μm, greater than or equal to 0.075 μm and less than or equal to 0.5 μm, greater than or equal to 0.15 μm and less than or equal to 3 μm, greater than or equal to 0.25 μm and less than or equal to 3 μm, or greater than or equal to 0.25 μm and less than or equal to 2 μm). Other ranges are also possible. The average diameter can be determined by scanning electron microscopy.

[0105] The fibers in the additional layers (if present) may have multiple suitable average lengths. In some embodiments, the average length of the fibers in the additional layers is greater than or equal to 0.01 mm, greater than or equal to 0.1 mm, greater than or equal to 0.2 mm, greater than or equal to 0.3 mm, greater than or equal to 0.4 mm, greater than or equal to 0.5 mm, greater than or equal to 0.75 mm, greater than or equal to 1 mm, greater than or equal to 1.25 mm, greater than or equal to 1.5 mm, greater than or equal to 2 mm, greater than or equal to 3 mm, greater than or equal to 4 mm, greater than or equal to 5 mm, greater than or equal to 6 mm, greater than or equal to 7.5 mm, greater than or equal to 10 mm, greater than or equal to 12.5 mm, greater than or equal to 15 mm, greater than or equal to 20 mm, greater than or equal to 25 mm, greater than or equal to 30 mm, greater than or equal to 40 mm, greater than or equal to 50 mm, or greater than or equal to 75 mm. In some embodiments, the average length of the fibers in the additional layers is less than or equal to 300 mm, less than or equal to 250 mm, less than or equal to 200 mm, less than or equal to 150 mm, less than or equal to 100 mm, less than or equal to 75 mm, less than or equal to 50 mm, less than or equal to 40 mm, less than or equal to 30 mm, less than or equal to 25 mm, less than or equal to 20 mm, less than or equal to 15 mm, less than or equal to 12.5 mm, less than or equal to 12 mm, less than or equal to 10 mm, less than or equal to 7.5 mm, less than or equal to 5 mm, less than or equal to 4 mm, less than or equal to 3 mm, less than or equal to 2.5 mm, less than or equal to 2 mm, less than or equal to 1.5 mm, less than or equal to 1.25 mm, less than or equal to 1 mm, less than or equal to 0.75 mm, less than or equal to 0.5 mm, or less than or equal to 0.4 mm. Combinations of the above ranges are also possible (e.g., greater than or equal to 0.01 mm and less than or equal to 300 mm, greater than or equal to 0.1 mm and less than or equal to 300 mm, greater than or equal to 0.1 mm and less than or equal to 25 mm, greater than or equal to 0.1 mm and less than or equal to 12 mm, greater than or equal to 0.3 mm and less than 100 mm, greater than or equal to 1 mm and less than or equal to 70 mm, greater than or equal to 1 mm and less than or equal to 10 mm, greater than or equal to 3 mm and less than or equal to 300 mm, greater than or equal to 6 mm and less than or equal to 100 mm, or greater than or equal to 1 mm and less than or equal to 50 mm). Other ranges are also possible.

[0106] In embodiments with more than one additional layer, each additional layer may independently contain fibers with an average length within one or more of the aforementioned ranges.

[0107] In some implementations, the additional layer comprises continuous fibers, which may have multiple suitable lengths. For example, the average fiber length in other layers can be greater than or equal to 100 mm, greater than or equal to 125 mm, greater than or equal to 150 mm, greater than or equal to 200 mm, greater than or equal to 250 mm, greater than or equal to 300 mm, greater than or equal to 400 mm, greater than or equal to 500 mm, greater than or equal to 750 mm, greater than or equal to 1 m, greater than or equal to 1.25 m, greater than or equal to 1.5 m, greater than or equal to 2 m, greater than or equal to 2.5 m, greater than or equal to 3 m, greater than or equal to 4 m, greater than or equal to 5 m, greater than or equal to 7.5 m, greater than or equal to 10 m, greater than or equal to 12.5 m, greater than or equal to 15 m, greater than or equal to 200 mm ... m, greater than or equal to 250 m, greater than or equal to 300 m, greater than or equal to 400 m, greater than or equal to 500 m, or greater than or equal to 750 m. In some implementations, the average length of fibers in the additional layers is less than or equal to 1 km, less than or equal to 750 m, less than or equal to 500 m, less than or equal to 400 m, less than or equal to 300 m, less than or equal to 250 m, less than or equal to 200 m, less than or equal to 150 m, less than or equal to 125 m, less than or equal to 100 m, less than or equal to 75 m, less than or equal to 50 m, less than or equal to 40 m, less than or equal to 30 m, less than or equal to 25 m, less than or equal to 20 m, less than or equal to 15 m, less than or equal to 12.5 m, less than or equal to 10 m, less than or equal to 7.5 m, less than or equal to 5 m, less than or equal to 4 m, less than or equal to 3 m, less than or equal to 2.5 m, less than or equal to 2 m, less than or equal to 1.5 m, less than or equal to 1.25 m, less than or equal to 1 m, less than or equal to 750 mm, less than or equal to 500 mm, less than or equal to 400 mm ... The ranges are mm, less than or equal to 300 mm, less than or equal to 250 mm, less than or equal to 200 mm, less than or equal to 150 mm, or less than or equal to 125 mm. Combinations of the above ranges are also possible (e.g., greater than or equal to 100 mm and less than or equal to 1 km, greater than or equal to 125 mm and less than or equal to 25 m, greater than or equal to 125 mm and less than or equal to 2 m). Other ranges are also possible.

[0108] In embodiments with more than one additional layer, each additional layer may independently contain fibers with an average length within one or more of the aforementioned ranges.

[0109] Some additional layers contain components other than fibers. For example, additional layers may contain adhesive resins. The adhesive resin may constitute less than or equal to 90% by weight, less than or equal to 80% by weight, less than or equal to 70% by weight, less than or equal to 60% by weight, less than or equal to 50% by weight, less than or equal to 40% by weight, less than or equal to 30% by weight, less than or equal to 25% by weight, less than or equal to 20% by weight, less than or equal to 15% by weight, less than or equal to 12.5% ​​by weight, less than or equal to 10% by weight, less than or equal to 7.5% by weight, less than or equal to 5% by weight, less than or equal to 4% by weight, less than or equal to 3% by weight, less than or equal to 2.5% by weight, less than or equal to 2% by weight, less than or equal to 1.5% by weight, less than or equal to 1.25% by weight, less than or equal to 1% by weight, less than or equal to 1% by weight, less than or equal to 0.75% by weight, less than or equal to 0.5% by weight, less than or equal to 0.4% by weight, less than or equal to 0.3% by weight, less than or equal to 0.25% by weight, less than or equal to 0.2% by weight, less than or equal to 0.15% by weight, less than or equal to 0.125% by weight, or less than or equal to 0.1% by weight. The adhesive resin may constitute 0% or more by weight, 0.1% or more by weight, 0.125% or more by weight, 0.15% or more by weight, 0.2% or more by weight, 0.25% or more by weight, 0.3% or more by weight, 0.4% or more by weight, 0.5% or more by weight, 0.75% or more by weight, 1% or more by weight, 1.25% or more by weight, 1.5% or more by weight, 2% or more by weight, 2.5% or more by weight, 3% or more by weight, 4% or more by weight, 5% or more by weight, 7.5% or more by weight, 10% or more by weight, 12.5% ​​or more by weight, 15% or more by weight, 20% or more by weight, or 25% or more by weight in the additional layers. Combinations of the above ranges are also possible (e.g., 0% or more by weight and 90% or less by weight, or 10% or more by weight and 30% or less by weight). Other ranges are also possible. In some implementations, the additional layer does not contain adhesive resin (i.e., the adhesive resin accounts for 0% by weight of the additional layer).

[0110] In embodiments with more than one additional layer, each additional layer may independently contain an amount of adhesive resin within one or more of the above-mentioned ranges. Suitable adhesive resins are described elsewhere herein.

[0111] The thickness of the additional layer can be selected as needed. For example, in some embodiments, the thickness of the additional layer can be greater than or equal to 10 nm, greater than or equal to 20 nm, greater than or equal to 30 nm, greater than or equal to 40 nm, greater than or equal to 50 nm, greater than or equal to 100 nm, greater than or equal to 500 nm, greater than or equal to 1 micrometer, greater than or equal to 0.02 mm, greater than or equal to 0.05 mm, greater than or equal to 0.1 mm, greater than or equal to 0.2 mm, greater than or equal to 0.4 mm, greater than or equal to 0.5 mm, greater than or equal to 0.8 mm, greater than or equal to 1.0 mm, greater than or equal to 2.0 mm, greater than or equal to 3.0 mm, or greater than or equal to 4.0 mm. In some cases, the thickness of additional layers can be less than or equal to 10 mm, less than or equal to 9 mm, less than or equal to 8 mm, less than or equal to 7 mm, less than or equal to 6 mm, less than or equal to 5 mm, less than or equal to 3 mm, less than or equal to 2 mm, less than or equal to 1.2 mm, less than or equal to 1 mm, less than or equal to 0.8 mm, less than or equal to 0.5 mm, less than or equal to 0.4 mm, or less than or equal to 0.2 mm. Combinations of the above ranges are also possible (e.g., thicknesses greater than or equal to 10 nm and less than or equal to 10 mm, greater than or equal to 0.02 mm and less than or equal to 10 mm, greater than or equal to 0.05 mm and less than or equal to 5 mm, greater than or equal to 0.1 mm and less than or equal to 5 mm, greater than or equal to 0.1 mm and less than or equal to 3 mm, or greater than or equal to 0.1 mm and less than or equal to 1 mm). Other values ​​for thickness are also possible. As determined herein, the thickness is 2 N / cm according to standard ISO 534 (2011). 2 Take the measurement.

[0112] When present, the additional layers can have multiple suitable densities. In some embodiments, the density of the additional layers is greater than or equal to 0.001%, greater than or equal to 0.01%, greater than or equal to 0.1%, greater than or equal to 1%, greater than or equal to 2%, greater than or equal to 3%, greater than or equal to 4%, greater than or equal to 5%, greater than or equal to 7.5%, greater than or equal to 10%, greater than or equal to 15%, greater than or equal to 20%, greater than or equal to 25%, greater than or equal to 30%, greater than or equal to 35%, greater than or equal to 40%, greater than or equal to 45%, greater than or equal to 50%, or greater than or equal to 60%. In some embodiments, the density of the additional layers is less than or equal to 70%, less than or equal to 60%, less than or equal to 50%, less than or equal to 45%, less than or equal to 40%, less than or equal to 35%, less than or equal to 30%, less than or equal to 25%, less than or equal to 20%, less than or equal to 15%, less than or equal to 10%, less than or equal to 7.5%, or less than or equal to 5%. Combinations of the above ranges are also possible (e.g., greater than or equal to 0.001% and less than or equal to 50%, greater than or equal to 0.01% and less than or equal to 25%, greater than or equal to 4% and less than or equal to 90%, greater than or equal to 4% and less than or equal to 50%, greater than or equal to 5% and less than or equal to 40%, or greater than or equal to 5% and less than or equal to 35%). Other ranges are also possible. Density can be measured as described elsewhere in this document. In embodiments with more than one additional layer, each additional layer may independently have a density within one or more of the above ranges.

[0113] When present, additional layers can have multiple suitable weights per unit area. In some implementations, the additional layer has a unit area weight greater than or equal to 0.001 gsm, greater than or equal to 0.01 gsm, greater than or equal to 0.1 gsm, greater than or equal to 1 gsm, greater than or equal to 2 gsm, greater than or equal to 5 gsm, greater than or equal to 7.5 gsm, greater than or equal to 10 gsm, greater than or equal to 12.5 gsm, greater than or equal to 15 gsm, greater than or equal to 17.5 gsm, greater than or equal to 20 gsm, greater than or equal to 25 gsm, greater than or equal to 30 gsm, greater than or equal to 400 gsm, greater than or equal to 50 gsm, greater than or equal to 75 gsm, greater than or equal to 100 gsm, greater than or equal to 150 gsm, greater than or equal to 200 gsm, greater than or equal to 250 gsm, greater than or equal to 300 gsm, or greater than or equal to 400 gsm. In some implementations, the additional layer has a unit area weight of less than or equal to 1000 gsm, less than or equal to 900 gsm, less than or equal to 800 gsm, less than or equal to 700 gsm, less than or equal to 600 gsm, less than or equal to 500 gsm, less than or equal to 400 gsm, less than or equal to 300 gsm, less than or equal to 250 gsm, less than or equal to 200 gsm, less than or equal to 150 gsm, less than or equal to 120 gsm, less than or equal to 100 gsm, less than or equal to 75 gsm, less than or equal to 50 gsm, less than or equal to 40 gsm, less than or equal to 30 gsm, less than or equal to 25 gsm, less than or equal to 20 gsm, less than or equal to 17.5 gsm, less than or equal to 15 gsm, less than or equal to 12.5 gsm, less than or equal to 10 gsm, or less than or equal to 7.5 gsm. Combinations of the above ranges are also possible (e.g., greater than or equal to 0.001 gsm and less than or equal to 1000 gsm, greater than or equal to 2 gsm and less than or equal to 1000 gsm, greater than or equal to 5 gsm and less than or equal to 500 gsm, greater than or equal to 10 gsm and less than or equal to 300 gsm, greater than or equal to 15 gsm and less than or equal to 500 gsm, greater than or equal to 20 gsm and less than or equal to 300 gsm, greater than or equal to 20 gsm and less than or equal to 120 gsm, or greater than or equal to 30 gsm and less than or equal to 200 gsm). Other ranges of weight per unit area are also possible. The weight per unit area of ​​additional layers can be determined according to ISO 536:2012.

[0114] In embodiments with more than one additional layer, each additional layer may independently have a unit area weight within one or more of the above ranges.

[0115] When present, the additional layer can have multiple suitable average flow orifice sizes. In some embodiments, the average flow orifice size of the additional layer is greater than or equal to 0.1 micrometer, greater than or equal to 0.125 micrometer, greater than or equal to 0.15 micrometer, greater than or equal to 0.2 micrometer, greater than or equal to 0.25 micrometer, greater than or equal to 0.3 micrometer, greater than or equal to 0.4 micrometer, greater than or equal to 0.5 micrometer, greater than or equal to 0.75 micrometer, greater than or equal to 1 micrometer, greater than or equal to 1.25 micrometer, greater than or equal to 1.5 micrometer, greater than or equal to 2 micrometer, greater than or equal to 2.5 micrometer, greater than or equal to 3 micrometer, and larger. The range is 4 micrometers or greater than or equal to 5 micrometers, 7.5 micrometers or greater than or equal to 7.5 micrometers, 10 micrometers or greater than or equal to 12.5 micrometers, 15 micrometers or greater than or equal to 15 micrometers, 20 micrometers or greater than or equal to 25 micrometers, 30 micrometers or greater than or equal to 35 micrometers, 40 micrometers or greater than or equal to 45 micrometers, 50 micrometers or greater than or equal to 75 micrometers, 100 micrometers or greater than or equal to 125 micrometers, 150 micrometers or greater than or equal to 150 micrometers, or 200 micrometers or greater than or equal to 200 micrometers. In some implementations, the average flow aperture of the additional layers is less than or equal to 300 micrometers, less than or equal to 250 micrometers, less than or equal to 200 micrometers, less than or equal to 150 micrometers, less than or equal to 125 micrometers, less than or equal to 100 micrometers, less than or equal to 75 micrometers, less than or equal to 50 micrometers, less than or equal to 45 micrometers, less than or equal to 40 micrometers, less than or equal to 35 micrometers, less than or equal to 30 micrometers, less than or equal to 25 micrometers, less than or equal to 20 micrometers, less than or equal to 15 micrometers, and less than or equal to... 12.5 micrometers, less than or equal to 10 micrometers, less than or equal to 7.5 micrometers, less than or equal to 5 micrometers, less than or equal to 3 micrometers, less than or equal to 2.5 micrometers, less than or equal to 2 micrometers, less than or equal to 1.5 micrometers, less than or equal to 1.25 micrometers, less than or equal to 1 micrometer, less than or equal to 1 micrometer, less than or equal to 0.4 micrometers, less than or equal to 0.3 micrometers, less than or equal to 0.2 micrometers, less than or equal to 0.15 micrometers, or less than or equal to 0.125 micrometers. Combinations of the above ranges are also possible (e.g., greater than or equal to 0.1 micrometers and less than or equal to 300 micrometers, greater than or equal to 0.1 micrometers and less than or equal to 250 micrometers, greater than or equal to 1 micrometer and less than or equal to 100 micrometers, greater than or equal to 0.1 micrometers and less than or equal to 50 micrometers, greater than or equal to 0.2 micrometers and less than or equal to 35 micrometers, or greater than or equal to 0.2 micrometers and less than or equal to 30 micrometers). Other ranges are also possible.

[0116] The average flow orifice diameter of the additional layers can be determined according to ASTM F316 (2003).

[0117] When present, additional layers can have multiple suitable air permeability rates. In some implementations, the permeability of the additional layers is greater than or equal to 0.5 CFM, greater than or equal to 0.75 CFM, greater than or equal to 1 CFM, greater than or equal to 1.25 CFM, greater than or equal to 1.5 CFM, greater than or equal to 2 CFM, greater than or equal to 2.5 CFM, greater than or equal to 3 CFM, greater than or equal to 4 CFM, greater than or equal to 5 CFM, greater than or equal to 7.5 CFM, greater than or equal to 8 CFM, greater than or equal to 10 CFM, greater than or equal to 12.5 CFM, greater than or equal to 15 CFM, greater than or equal to 20 CFM, greater than or equal to 300 CFM, greater than or equal to 400 CFM, greater than or equal to 50 CFM, greater than or equal to 75 CFM, greater than or equal to 100 CFM, greater than or equal to 125 CFM, greater than or equal to 150 CFM, greater than or equal to 200 CFM, greater than or equal to 250 CFM, greater than or equal to 300 CFM, greater than or equal to 400 CFM, greater than or equal to 400 CFM. CFM, greater than or equal to 500 CFM, greater than or equal to 750 CFM, greater than or equal to 1000 CFM, greater than or equal to 1250 CFM, greater than or equal to 1500 CFM, greater than or equal to 2000 CFM, greater than or equal to 2500 CFM, greater than or equal to 3000 CFM, or greater than or equal to 5000 CFM.In some implementations, the permeability of the additional layers is less than or equal to 8000 CFM, less than or equal to 5000 CFM, less than or equal to 3000 CFM, less than or equal to 2500 CFM, less than or equal to 2000 CFM, less than or equal to 1500 CFM, less than or equal to 1400 CFM, less than or equal to 1250 CFM, less than or equal to 1000 CFM, less than or equal to 750 CFM, less than or equal to 500 CFM, less than or equal to 400 CFM, less than or equal to 300 CFM, less than or equal to 200 CFM, less than or equal to 150 CFM, less than or equal to 125 CFM, less than or equal to 100 CFM, less than or equal to 75 CFM, less than or equal to 50 CFM, less than or equal to 40 CFM, less than or equal to 30 CFM, less than or equal to 25 CFM, less than or equal to 20 CFM, less than or equal to 15 CFM, or less than or equal to 12.5 CFM. CFM, less than or equal to 10 CFM, less than or equal to 7.5 CFM, less than or equal to 5 CFM, less than or equal to 4 CFM, less than or equal to 3 CFM, less than or equal to 2.5 CFM, less than or equal to 2 CFM, less than or equal to 1.5 CFM, less than or equal to 1.25 CFM, less than or equal to 1 CFM, or less than or equal to 0.75 CFM. Combinations of the above ranges are also possible (e.g., greater than or equal to 0.5 CFM and less than or equal to 8000 CFM, greater than or equal to 0.5 CFM and less than or equal to 2000 CFM, greater than or equal to 1 CFM and less than or equal to 1400 CFM, greater than or equal to 0.5 CFM and less than or equal to 800 CFM, greater than or equal to 1 CFM and less than or equal to 500 CFM, greater than or equal to 0.5 CFM and less than or equal to 400 CFM, greater than or equal to 0.5 CFM and less than or equal to 200 CFM, greater than or equal to 1 CFM and less than or equal to 150 CFM, greater than or equal to 5 CFM and less than or equal to 500 CFM, greater than or equal to 8 CFM and less than or equal to 400 CFM, or greater than or equal to 1 CFM and less than or equal to 100 CFM). Other ranges are also possible.

[0118] Air permeability can be determined according to ASTM test standard D737-04 (2016) at a pressure of 125 Pa.

[0119] When present, the additional layer can have any suitable dust holding capacity. In some embodiments, the dust holding capacity of the additional layer is greater than or equal to 10 gsm, greater than or equal to 20 gsm, greater than or equal to 30 gsm, greater than or equal to 40 gsm, greater than or equal to 50 gsm, greater than or equal to 75 gsm, greater than or equal to 100 gsm, greater than or equal to 125 gsm, greater than or equal to 150 gsm, greater than or equal to 200 gsm, greater than or equal to 250 gsm, greater than or equal to 300 gsm, greater than or equal to 350 gsm, or greater than or equal to 400 gsm. In some implementations, the holding capacity of the additional layers is less than or equal to 500 gsm, less than or equal to 450 gsm, less than or equal to 400 gsm, less than or equal to 350 gsm, less than or equal to 300 gsm, less than or equal to 250 gsm, less than or equal to 200 gsm, less than or equal to 150 gsm, less than or equal to 125 gsm, less than or equal to 100 gsm, less than or equal to 75 gsm, or less than or equal to 50 gsm. Combinations of these ranges are also possible (e.g., greater than or equal to 10 gsm and less than or equal to 500 gsm, or greater than or equal to 20 gsm and less than or equal to 450 gsm).

[0120] Dust holding capacity can be measured according to ISO 19438 (2013) using ISO intermediate test dust (A3).

[0121] When present, the additional layer (e.g., a backing layer, an additional layer) can have any suitable pressure drop. In some embodiments, the pressure drop of the additional layer is greater than or equal to 0.05 kPa, greater than or equal to 0.1 kPa, greater than or equal to 0.3 kPa, greater than or equal to 0.5 kPa, greater than or equal to 1 kPa, greater than or equal to 3 kPa, greater than or equal to 5 kPa, greater than or equal to 10 kPa, greater than or equal to 15 kPa, greater than or equal to 20 kPa, greater than or equal to 25 kPa, greater than or equal to 30 kPa, greater than or equal to 40 kPa, greater than or equal to 50 kPa, or greater than or equal to 60 kPa. In some implementations, the pressure drop of the additional layer is less than or equal to 80 kPa, less than or equal to 75 kPa, less than or equal to 70 kPa, less than or equal to 65 kPa, less than or equal to 60 kPa, less than or equal to 55 kPa, less than or equal to 50 kPa, less than or equal to 45 kPa, less than or equal to 40 kPa, less than or equal to 35 kPa, less than or equal to 30 kPa, less than or equal to 25 kPa, less than or equal to 20 kPa, less than or equal to 15 kPa, less than or equal to 10 kPa, or less than or equal to 5 kPa. Combinations of these ranges are also possible (e.g., greater than or equal to 0.05 kPa and less than or equal to 80 kPa or greater than or equal to 0.1 kPa and less than or equal to 50 kPa).

[0122] Pressure drop can be measured according to ASTM D2 986-91.

[0123] In some embodiments, additional layers may be treated (e.g., to make them more oleophobic). For example, the additional layers may contain oleophobic components, such as oleophobic additives or oleophobic coatings, and / or may have an oil rating greater than or equal to 1. In some embodiments, one or more layers having oleophobic properties (e.g., one or more layers containing oleophobic components, one or more layers with an oil rating greater than or equal to 1) may impart one or more benefits to the filter media as a whole, such as low pressure drop under high oil loads, high gamma under high oil loads, and / or low permeability under high oil loads. In applications where the filter media is located in an environment with moderate or high ambient oil levels, one or more of these properties may be advantageous. For example, the filter media may be used in cleanrooms (e.g., pharmaceutical cleanrooms, electronic cleanrooms, cleanrooms for integrated circuit manufacturing), gas turbines (e.g., offshore gas turbines), indoor air purifiers, face masks, vacuum cleaners, paint booths, and / or for filtering oily aerosols. In some implementations, the filter media having one or more layers with oleophobic properties (e.g., one or more layers containing oleophobic components, one or more layers with an oil grade greater than or equal to 1) can be a HEPA filter, a ULPA filter, and / or an HVAC filter. Other types of filter media including oleophobic layers are also possible.

[0124] In some embodiments, one or more additional layers within the filter medium have an oil grade greater than or equal to 1, greater than or equal to 2, greater than or equal to 3, greater than or equal to 4, greater than or equal to 4.5, greater than or equal to 5, greater than or equal to 5.5, greater than or equal to 6, greater than or equal to 6.5, greater than or equal to 7, or greater than or equal to 7.5. In some embodiments, one or more additional layers within the filter medium have an oil grade less than or equal to 8, less than or equal to 7.5, less than or equal to 7, less than or equal to 6.5, less than or equal to 6, less than or equal to 5.5, less than or equal to 5, less than or equal to 4.5, less than or equal to 4, less than or equal to 3, or less than or equal to 2. Combinations of the above ranges are also possible (e.g., greater than or equal to 1 and less than or equal to 8, greater than or equal to 1 and less than or equal to 8, greater than or equal to 1 and less than or equal to 6, or greater than or equal to 5 and less than or equal to 6). Other ranges are also possible.

[0125] The oil grades described herein are determined according to AATCC TM 118 (1997) measurements at 23°C and 50% relative humidity (RH). In short, five drops of each test oil (average droplet diameter approximately 2 mm) are placed at five different locations on the surface of the fiber mesh. After 30 seconds of contact with the fiber mesh at 23°C and 50% RH, the test oil with the highest surface tension (e.g., a contact angle greater than or equal to 90 degrees with the surface) that does not wet the surface of the fiber mesh corresponds to the oil grade (listed in Table 1). For example, if a test oil with a surface tension of 26.6 mN / m does not wet the surface of the fiber mesh after 30 seconds (i.e., a contact angle greater than or equal to 90 degrees with the surface), while a test oil with a surface tension of 25.4 mN / m wets the surface of the fiber mesh within 30 seconds, then the oil grade of the fiber mesh is 4. As another example, if a test oil with a surface tension of 25.4 mN / m does not wet the surface of the fiber web after 30 seconds, while a test oil with a surface tension of 23.8 mN / m wets the surface of the fiber web within 30 seconds, then the oil grade of the fiber web is 5. As yet another example, if a test oil with a surface tension of 23.8 mN / m does not wet the surface of the fiber web after 30 seconds, while a test oil with a surface tension of 21.6 mN / m wets the surface of the fiber web within 30 seconds, then the oil grade of the fiber web is 6. In some embodiments, if three or more of five droplets partially wet the surface in a given test (e.g., forming droplets on the surface, but not perfectly round droplets), the oil grade is expressed as the nearest 0.5 value determined by subtracting 0.5 from the number of test liquids. As an example, if the test oil with a surface tension of 25.4 mN / m does not wet the surface of the fiber web after 30 seconds, while the test oil with a surface tension of 23.8 mN / m only partially wets the surface of the fiber web within 30 seconds after 30 seconds (e.g., three or more of the test droplets form non-circular droplets on the surface of the fiber web), then the oil grade of the fiber web is 5.5.

[0126]

[0127] The filter media described herein may include any suitable number of total layers (including all backing layers (e.g., reinforced with a surface-treated fiber web of the type described above), adsorbent particle layers, and / or additional layers). In some embodiments, the filter media includes 1 or more, 2 or more, 3 or more, 4 or more, 5 or more, 6 or more, 7 or more, 8 or more, 9 or more, 10 or more, 12 or more, 14 or more, 16 or more, or 18 or more total layers. In some embodiments, the filter media includes 20 or more, 18 or more, 16 or more, 14 or more, 12 or more, 10 or more, 9 or more, 8 or more, 7 or more, 6 or more, 5 or more, 4 or more, 3 or more, or 2 or more total layers. Combinations of these ranges are also possible (e.g., greater than or equal to 1 and less than or equal to 25, greater than or equal to 1 and less than or equal to 10, or greater than or equal to 1 and less than or equal to 4). Other ranges are also possible.

[0128] In some embodiments, two or more layers of the filter media can be formed individually and combined by any suitable method (e.g., lamination, finishing) or by using an adhesive. The two or more layers can be formed using different or the same processes. For example, each layer can be formed independently by electrospinning, non-wet web forming processes (e.g., meltblowing, melt spinning, centrifugal spinning, electrospinning, dry web forming, air-laid web forming), wet web forming, or any other suitable process.

[0129] Different layers can be adhered together by any suitable method. For example, layers can be adhered to each other and / or fused together on either side by an adhesive. Lamination and calendering methods can also be used. In some embodiments, an additional layer is formed from any type of fiber or fiber blend via a wet or non-wet web forming process and is suitably adhered to the other layer.

[0130] In some embodiments, the filter medium comprises an adhesive positioned between two or more layers. Also as described above, some filter media described herein comprise an adhesive positioned between two or more pairs of layers. It should be understood that the adhesive positioned between any particular pair of layers may have some or all of the properties described below regarding the adhesive. It should also be understood that the filter medium may include two locations where an adhesive having the same properties is positioned, and / or may include two or more locations where an adhesive differs in one or more respects.

[0131] In some embodiments, the filter medium comprises an adhesive that is a solvent-based adhesive resin. As used herein, a solvent-based adhesive resin is an adhesive capable of undergoing a liquid-to-solid transition upon evaporation of the solvent from the resin. The solvent-based adhesive resin can be applied in a liquid state. Subsequently, the present solvent can be evaporated to produce a solid adhesive. Therefore, solvent-based adhesives can be considered different from hot-melt adhesives, which do not contain volatile solvents (e.g., solvents that evaporate under normal operating conditions) and typically undergo a liquid-to-solid transition upon cooling. In embodiments where the adhesive is present at more than one location, each location where the adhesive is present may independently comprise an adhesive that is a solvent-based adhesive resin.

[0132] Desired properties of an adhesive may include sufficient tackiness and open time (i.e., the amount of time the adhesive remains tacky after exposure to an ambient atmosphere). Without being bound by theory, the tackiness of an adhesive can depend on both the glass transition temperature of the adhesive and the molecular weight of any of its polymeric components. Higher glass transition values ​​and lower molecular weight values ​​can promote enhanced tackiness, and higher molecular weight values ​​can generate higher cohesive forces and higher bond strength in the adhesive. In some embodiments, adhesives with glass transition temperatures and / or molecular weights within one or more ranges described herein can provide suitable values ​​for both tackiness and open time. For example, an adhesive can be configured to maintain tackiness for a relatively long period (e.g., the adhesive can remain tacky after any initially present solvent has completely evaporated, and / or can remain tacky indefinitely when held at room temperature). In some embodiments, the open time of the adhesive can be less than or equal to 24 hours, less than or equal to 12 hours, less than or equal to 6 hours, less than or equal to 1 hour, less than or equal to 30 minutes, less than or equal to 15 minutes, less than or equal to 10 minutes, less than or equal to 5 minutes, less than or equal to 3 minutes, less than or equal to 1 minute, less than or equal to 30 seconds, or less than or equal to 10 seconds. In some embodiments, the open time of the adhesive can be at least 1 second, at least 10 seconds, at least 15 seconds, at least 30 seconds, at least 1 minute, at least 3 minutes, at least 5 minutes, at least 10 minutes, at least 15 minutes, at least 30 minutes, at least 1 hour, at least 6 hours, or at least 12 hours. Combinations of the above ranges are also possible (e.g., at least 1 second and less than or equal to 24 hours). Other values ​​are also possible. In embodiments where the adhesive is present at more than one location, each location where the adhesive is present can independently contain an adhesive with an open time within one or more of the above ranges.

[0133] Non-limiting examples of suitable adhesives include adhesives comprising: acrylates, acrylate copolymers, poly(urethane), poly(ester), poly(vinyl alcohol), ethylene-vinyl acetate copolymers, silicone solvents, poly(olefins), synthetic rubbers and / or natural rubbers, synthetic elastomers, ethylene-acrylic acid copolymers, ethylene-methacrylate copolymers, ethylene-methyl methacrylate copolymers, poly(vinylidene chloride), poly(amide), epoxy resins, melamine resins, poly(isobutylene), styrene block copolymers, styrene-butadiene rubber, aliphatic urethane acrylates, and / or phenolic resins. In embodiments where the adhesive is present at more than one location, each location where the adhesive is present may independently contain an adhesive comprising one or more of the materials described above.

[0134] When present, the adhesive may contain a crosslinking agent and / or may be crosslinked. In some embodiments, the crosslinking agent is less than or equal to 3000 g / mol. In some embodiments, the crosslinking agent is a small molecule as described above and / or the crosslinking agent is a reaction product of a small molecule crosslinking agent as described above. In some embodiments, the adhesive contains a small molecule crosslinking agent (and / or its reaction product) that is one or more of the following: carbodiimide, isocyanate, aziridine, zirconium compound (e.g., zirconium carbonate), metal ester, metal chelate, polyfunctional acrylimide, and amino resin. In some embodiments, the adhesive contains at least one polymer and / or prepolymer having one or more reactive functional groups capable of reacting with the crosslinking agent and / or a reaction product containing one or more reactive functional groups on the polymer and / or prepolymer reacting with the crosslinking agent. Non-limiting examples of suitable reactive functional groups include alcohols, carboxylic acids, epoxy groups, amino groups, and amino groups. In some embodiments, the filter media contains an adhesive containing one or more polymers and / or prepolymers that can self-crosslink via functional groups attached thereto. In some embodiments, the filter medium comprises an adhesive containing a self-crosslinking reaction product of one or more polymers and / or prepolymers. In embodiments where the adhesive is present at more than one location, each location where the adhesive is present may independently contain an adhesive containing one or more of the aforementioned materials.

[0135] When present, the small molecule crosslinking agent and / or the crosslinks of its reaction products can constitute any suitable amount of the adhesive. In some embodiments, the weight percentage of the crosslinking agent and / or the crosslinks of its reaction products relative to the total mass of the adhesive is greater than or equal to 0.1 wt%, greater than or equal to 0.2 wt%, greater than or equal to 0.5 wt%, greater than or equal to 1 wt%, greater than or equal to 2 wt%, greater than or equal to 5 wt%, greater than or equal to 10 wt%, greater than or equal to 15 wt%, greater than or equal to 20 wt%, or greater than or equal to 25 wt%. In some embodiments, the weight percentage of the small molecule crosslinking agent and / or the crosslinks of its reaction products relative to the total mass of the adhesive is less than or equal to 30 wt%, less than or equal to 25 wt%, less than or equal to 20 wt%, less than or equal to 15 wt%, less than or equal to 10 wt%, less than or equal to 5 wt%, less than or equal to 2 wt%, less than or equal to 1 wt%, less than or equal to 0.5 wt%, or less than or equal to 0.2 wt%. Combinations of the above ranges are also possible (e.g., greater than or equal to 0.1% by weight and less than or equal to 30% by weight, or greater than or equal to 1% by weight and less than or equal to 20% by weight). Other ranges are also possible. In embodiments where the adhesive is present at more than one location, each location where the adhesive is present may independently contain an adhesive comprising one or more of the small molecule crosslinking agents and / or crosslinking bonds of their reaction products in the amounts described above.

[0136] The adhesive and / or any small molecule crosslinking agent therein may be capable of crosslinking at any suitable temperature and / or may have been crosslinked at any suitable temperature. In some embodiments, the adhesive may be capable of crosslinking at the following temperatures and / or may have been crosslinked at the following temperatures: ≥24°C, ≥40°C, ≥50°C, ≥60°C, ≥70°C, ≥80°C, ≥90°C, ≥100°C, ≥110°C, ≥120°C, ≥130°C, or ≥140°C. In some embodiments, the adhesive may be capable of crosslinking at temperatures below 150°C, below 140°C, below 130°C, below 120°C, below 110°C, below 100°C, below 90°C, below 80°C, below 70°C, below 60°C, below 50°C, or below 40°C. Combinations of the above ranges are also possible (e.g., above 25°C and below 150°C, or above 25°C and below 130°C). Other ranges are also possible. In embodiments where the adhesive is present at more than one location, each location where the adhesive is present may independently contain an adhesive capable of crosslinking at temperatures within one or more of the above ranges and / or already crosslinked at temperatures within one or more of the above ranges.

[0137] When present, the adhesive may contain a solvent and / or may be formed from a composition containing a solvent (e.g., from which the solvent has evaporated). As an example, some embodiments involve an adhesive applied to a layer or filter medium when dissolved or suspended in a solvent. Non-limiting examples of suitable solvents include water, hydrocarbon solvents, ketones, aromatic solvents, fluorinated solvents, toluene, heptane, acetone, n-butyl acetate, methyl ethyl ketone, dichloromethane, naphtha, and solvent oils. In embodiments where the adhesive is present at more than one location, each location where the adhesive is present may independently contain one or more of the aforementioned solvents and / or may be formed from a composition containing one or more of the aforementioned solvents.

[0138] When present, the adhesive can have a relatively low glass transition temperature. In some embodiments, the glass transition temperature of the adhesive is less than or equal to 60°C, less than or equal to 50°C, less than or equal to 45°C, less than or equal to 40°C, less than or equal to 35°C, less than or equal to 30°C, less than or equal to 25°C, less than or equal to 24°C, less than or equal to 20°C, less than or equal to 15°C, less than or equal to 10°C, less than or equal to 5°C, less than or equal to 0°C, less than or equal to -5°C, less than or equal to -10°C, less than or equal to -20°C, less than or equal to -30°C, less than or equal to -40°C, less than or equal to -50°C, less than or equal to -60°C, less than or equal to -70°C, less than or equal to -80°C, less than or equal to -90°C, less than or equal to -100°C, or less than or equal to -110°C. In some embodiments, the glass transition temperature of the adhesive is greater than or equal to -125°C, greater than or equal to -110°C, greater than or equal to -100°C, greater than or equal to -90°C, greater than or equal to -80°C, greater than or equal to -70°C, greater than or equal to -60°C, greater than or equal to -50°C, greater than or equal to -40°C, greater than or equal to -30°C, greater than or equal to -20°C, greater than or equal to -10°C, greater than or equal to 0°C, greater than or equal to 5°C, greater than or equal to 10°C, greater than or equal to 24°C, greater than or equal to 25°C, greater than or equal to 40°C, or greater than or equal to 50°C. Combinations of the above ranges are also possible (e.g., greater than or equal to -125°C and less than or equal to 60°C, or greater than or equal to -100°C and less than or equal to 25°C). Other ranges are also possible. The glass transition temperature value of the adhesive can be measured by differential scanning calorimetry as described above. In embodiments where the adhesive is present at more than one location, each location where the adhesive is present may independently contain an adhesive with a glass transition temperature within one or more of the ranges described above.

[0139] When present, the adhesive can have several suitable molecular weights. In some embodiments, the number average molecular weight of the adhesive is greater than or equal to 10 kDa, greater than or equal to 30 kDa, greater than or equal to 50 kDa, greater than or equal to 100 kDa, greater than or equal to 300 kDa, greater than or equal to 500 kDa, greater than or equal to 1000 kDa, greater than or equal to 2000 kDa, or greater than or equal to 3000 kDa. In some embodiments, the number average molecular weight of the adhesive is less than or equal to 5000 kDa, less than or equal to 4000 kDa, less than or equal to 3000 kDa, less than or equal to 1000 kDa, less than or equal to 50 kDa, or less than or equal to 30 kDa. Combinations of the above ranges are also possible (e.g., greater than or equal to 10 kDa and less than or equal to 5000 kDa, or greater than or equal to 30 kDa and less than or equal to 3000 kDa). Other ranges are also possible. Number-average molecular weight can be measured by light scattering. In embodiments where the adhesive is present at more than one location, each location where the adhesive is present may independently contain an adhesive with a molecular weight within one or more of the ranges described above.

[0140] When present, the adhesive can have several suitable unit area weights. In some embodiments, the unit area weight of the adhesive is greater than or equal to 0.05 gsm, greater than or equal to 0.1 gsm, greater than or equal to 0.2 gsm, greater than or equal to 0.5 gsm, greater than or equal to 1 gsm, greater than or equal to 2 gsm, or greater than or equal to 5 gsm. In some embodiments, the unit area weight of the adhesive is less than or equal to 10 gsm, less than or equal to 5 gsm, less than or equal to 2 gsm, less than or equal to 1 gsm, less than or equal to 0.5 gsm, less than or equal to 0.2 gsm, or less than or equal to 0.1 gsm. Combinations of the above ranges are also possible (e.g., greater than or equal to 0.05 gsm and less than or equal to 10 gsm, or greater than or equal to 0.1 gsm and less than or equal to 5 gsm). Other ranges are also possible. In embodiments where the adhesive is present at more than one location, each location where the adhesive is present may independently contain adhesive with a unit area weight within one or more of the ranges described above.

[0141] In embodiments where the filter media comprises one or more adhesives, the total unit area weight of the adhesives together in the filter media (i.e., the sum of the unit area weights of the adhesives at each location) can be greater than or equal to 0.05 gsm, greater than or equal to 0.1 gsm, greater than or equal to 0.2 gsm, greater than or equal to 0.5 gsm, greater than or equal to 1 gsm, greater than or equal to 2 gsm, or greater than or equal to 5 gsm. In some embodiments, the total unit area weight of the adhesives together in the filter media can be less than or equal to 10 gsm, less than or equal to 5 gsm, less than or equal to 2 gsm, less than or equal to 1 gsm, less than or equal to 0.5 gsm, less than or equal to 0.2 gsm, or less than or equal to 0.1 gsm. Combinations of the above ranges are also possible (e.g., greater than or equal to 0.05 gsm and less than or equal to 10 gsm, or greater than or equal to 0.1 gsm and less than or equal to 5 gsm). Other ranges are also possible.

[0142] When present, an adhesive can bond two or more layers, with the adhesive positioned between them, together. The bond strength between the two layers can be relatively high. For example, the adhesive can bond two layers together with a bond strength greater than or equal to 100 g / inch. 2 ≥150 g / inch 2 ≥200 g / inch 2 ≥500 g / inch 2 ≥750 g / inch 2 ≥1000 g / inch 2 ≥1250 g / inch 2 ≥1500 g / inch 2 ≥1750 g / inch 2 ≥2000 g / inch 2 ≥2250 g / inch 2 ≥2500 g / inch 2 ≥2750 g / inch 2 ≥3000 g / inch 2 ≥3250 g / inch 2 ≥3500 g / inch 2 ≥3750 g / inch 2 ≥4000 g / inch 2 ≥4250 g / inch 2 ≥4500 g / inch2 or greater than or equal to 4750 g / inch 2 In some implementations, the adhesive bonds the two layers together with a bond strength of less than or equal to 5000 g / inch. 2 Less than or equal to 4750 g / inch 2 Less than or equal to 4500 g / inch 2 Less than or equal to 4250 g / inch 2 Less than or equal to 4000 g / inch 2 Less than or equal to 3750 g / inch 2 Less than or equal to 3500 g / inch 2 Less than or equal to 3250 g / inch 2 Less than or equal to 3000 g / inch 2 Less than or equal to 2750 g / inch 2 Less than or equal to 2500 g / inch 2 Less than or equal to 2250 g / inch 2 Less than or equal to 2000 g / inch 2 Less than or equal to 1750 g / inch 2 Less than or equal to 1500 g / inch 2 Less than or equal to 1250 g / inch 2 Less than or equal to 1000 g / inch 2 Less than or equal to 750 g / inch 2 Less than or equal to 500 g / inch 2 Less than or equal to 200g / inch 2 or less than or equal to 150 g / inch 2 Combinations of the above ranges are also possible (e.g., greater than or equal to 100 g / inch). 2 And less than or equal to 5000 g / inch 2 or greater than or equal to 150 g / inch 2 And less than or equal to 3000 g / inch 2 Other ranges are also possible. In embodiments where the adhesive is present at more than one location, each location where the adhesive is present may independently contain an adhesive that bonds the two layers together with a bond strength within one or more of the aforementioned ranges. In some embodiments, the entire filter media as a whole has an internal bond strength within one or more of the aforementioned ranges. The bond strength of the entire filter media as a whole is equivalent to the weakest bond strength between the two layers of the media.

[0143] The bond strength (e.g., internal bond strength) between two layers (e.g., two layers bonded together by an adhesive) can be determined using a z-axis peel strength test. In short, the bond strength can be determined by the following steps: First, a 1-inch × 1-inch sample is mounted on a 1-inch × 1-inch × 0.5-inch steel block using double-sided tape. Then, the sample block is mounted on the non-transverse head of a tensile testing machine using double-sided tape, and another steel block of the same size is attached to the transverse head. The transverse head is lowered and bonded to the sample on the steel block on the non-transverse head. Sufficient pressure is applied to bond the steel blocks together via the mounted sample. The transverse head is then moved at a transverse speed of 1 inch / minute, and the maximum load is obtained from the peak of the stress-strain curve. The bond strength (e.g., internal bond strength) between the two layers is considered equivalent to the maximum load measured in this step.

[0144] The filter media described herein can have any of a number of suitable weights per unit area. In some implementations, the weight per unit area of ​​the filter media is greater than or equal to 5 gsm, greater than or equal to 10 gsm, greater than or equal to 20 gsm, greater than or equal to 40 gsm, greater than or equal to 60 gsm, greater than or equal to 80 gsm, greater than or equal to 100 gsm, greater than or equal to 150 gsm, greater than or equal to 200 gsm, greater than or equal to 250 gsm, greater than or equal to 300 gsm, greater than or equal to 350 gsm, greater than or equal to 400 gsm, greater than or equal to 450 gsm, greater than or equal to 500 gsm, greater than or equal to 600 gsm, greater than or equal to 700 gsm, greater than or equal to 800 gsm, greater than or equal to 900 gsm, greater than or equal to 1000 gsm, greater than or equal to 1100 gsm, greater than or equal to 1200 gsm, and greater than or equal to 1300 gsm. The weight per unit area of ​​the filter media is less than or equal to 1500 gsm, or greater than or equal to 1400 gsm. In some implementations, the weight per unit area of ​​the filter media is less than or equal to 1500 gsm, less than or equal to 1400 gsm, less than or equal to 1300 gsm, less than or equal to 1200 gsm, less than or equal to 1100 gsm, less than or equal to 1000 gsm, less than or equal to 900 gsm, less than or equal to 800 gsm, less than or equal to 700 gsm, less than or equal to 600 gsm, less than or equal to 500 gsm, less than or equal to 450 gsm, less than or equal to 400 gsm, less than or equal to 350 gsm, less than or equal to 300 gsm, less than or equal to 250 gsm, less than or equal to 200 gsm, less than or equal to 150 gsm, less than or equal to 100 gsm, less than or equal to 80 gsm, less than or equal to 60 gsm, less than or equal to 400 gsm, or less than or equal to 400 gsm. gsm, less than or equal to 20 gsm, or less than or equal to 10 gsm. Combinations of these ranges are also possible (e.g., greater than or equal to 5 gsm and less than or equal to 1500 gsm, greater than or equal to 5 gsm and less than or equal to 1000 gsm, or greater than or equal to 10 gsm and less than or equal to 500 gsm). Other ranges are also possible.

[0145] The weight per unit area of ​​the filter media can be determined according to ISO 536:2012.

[0146] The filter media described herein may have any of a number of suitable dust holding capacities. In some embodiments, the dust holding capacity of the filter media is greater than or equal to 1 gsm, greater than or equal to 5 gsm, greater than or equal to 10 gsm, greater than or equal to 20 gsm, greater than or equal to 50 gsm, greater than or equal to 80 gsm, greater than or equal to 100 gsm, greater than or equal to 150 gsm, greater than or equal to 200 gsm, greater than or equal to 250 gsm, greater than or equal to 300 gsm, greater than or equal to 350 gsm, greater than or equal to 400 gsm, greater than or equal to 450 gsm, greater than or equal to 500 gsm, greater than or equal to 550 gsm, greater than or equal to 600 gsm, or greater than or equal to 650 gsm. In some implementations, the dust holding capacity of the filter media is less than or equal to 700 gsm, less than or equal to 650 gsm, less than or equal to 600 gsm, less than or equal to 550 gsm, less than or equal to 500 gsm, less than or equal to 450 gsm, less than or equal to 400 gsm, less than or equal to 350 gsm, less than or equal to 300 gsm, less than or equal to 250 gsm, less than or equal to 200 gsm, less than or equal to 150 gsm, less than or equal to 100 gsm, less than or equal to 80 gsm, less than or equal to 50 gsm, less than or equal to 20 gsm, less than or equal to 10 gsm, or less than or equal to 5 gsm. Combinations of these ranges are also possible (e.g., greater than or equal to 1 gsm and less than or equal to 700 gsm, greater than or equal to 1 gsm and less than or equal to 500 gsm, or greater than or equal to 10 gsm and less than or equal to 450 gsm). Other ranges are also possible.

[0147] Dust holding capacity can be measured on a multipass filter test stand manufactured by FTI according to ISO 16889 (2008) (modified with reference to test plate samples). Measurements may include the use of Aviation Hydraulic Fluid AERO HFA MIL H-5606A manufactured by Mobil, in which ISO intermediate test dust (A3) is dispersed at 10 mg / L BUGL. The aviation hydraulic fluid can pass through a surface-treated fiber web at a face velocity of 1.7 L / min, and dust holding capacity can be measured when the pressure drop across the fiber web reaches 200 kPa higher than the initial pressure drop.

[0148] The filter media can have any suitable thickness. For example, in some embodiments, the thickness of the filter media is greater than or equal to 0.01 mm, greater than or equal to 0.1 mm, greater than or equal to 0.05 mm, greater than or equal to 1 mm, greater than or equal to 2 mm, greater than or equal to 3 mm, greater than or equal to 4 mm, greater than or equal to 5 mm, greater than or equal to 6 mm, greater than or equal to 7 mm, greater than or equal to 8 mm, greater than or equal to 9 mm, greater than or equal to 10 mm, greater than or equal to 15 mm, greater than or equal to 20 mm, or greater than or equal to 25 mm. In some embodiments, the thickness of the filter medium is less than or equal to 30 mm, less than or equal to 28 mm, less than or equal to 25 mm, less than or equal to 23 mm, less than or equal to 20 mm, less than or equal to 18 mm, less than or equal to 15 mm, less than or equal to 13 mm, less than or equal to 10 mm, less than or equal to 9 mm, less than or equal to 8 mm, less than or equal to 7 mm, less than or equal to 6 mm, less than or equal to 5 mm, less than or equal to 4 mm, less than or equal to 3 mm, less than or equal to 2 mm, or less than or equal to 1 mm. Combinations of these ranges are also possible (e.g., greater than or equal to 0.01 mm and less than or equal to 30 mm, or greater than or equal to 0.1 mm and less than or equal to 20 mm). Other ranges are also possible.

[0149] The thickness of the filter media can be specified according to ISO 534 (2011) at 2 N / cm. 2 The decision has been made.

[0150] The filter media can have any suitable average flow pore size. For example, in some cases, the average flow pore size of the filter media is greater than or equal to 0.001 micrometers, greater than or equal to 0.01 micrometers, greater than or equal to 0.1 micrometers, greater than or equal to 0.3 micrometers, greater than or equal to 0.5 micrometers, greater than or equal to 0.7 micrometers, greater than or equal to 1 micrometer, greater than or equal to 2 micrometers, greater than or equal to 3 micrometers, greater than or equal to 5 micrometers, greater than or equal to 7 micrometers, greater than or equal to 10 micrometers, greater than or equal to 15 micrometers, greater than or equal to 20 micrometers, greater than or equal to 30 micrometers, greater than or equal to 40 micrometers, greater than or equal to 50 micrometers, greater than or equal to 60 micrometers, greater than or equal to 70 micrometers, greater than or equal to 80 micrometers, or greater than or equal to 90 micrometers. In some cases, the average flow pore size of the filter media is less than or equal to 100 micrometers, less than or equal to 95 micrometers, less than or equal to 90 micrometers, less than or equal to 85 micrometers, less than or equal to 80 micrometers, less than or equal to 75 micrometers, less than or equal to 70 micrometers, less than or equal to 65 micrometers, less than or equal to 60 micrometers, less than or equal to 55 micrometers, less than or equal to 50 micrometers, less than or equal to 40 micrometers, less than or equal to 30 micrometers, less than or equal to 20 micrometers, less than or equal to 15 micrometers, less than or equal to 10 micrometers, less than or equal to 7 micrometers, less than or equal to 5 micrometers, less than or equal to 3 micrometers, less than or equal to 2 micrometers, or less than or equal to 1 micrometer. Combinations of these ranges are also possible (e.g., greater than or equal to 0.001 micrometers and less than or equal to 100 micrometers, greater than or equal to 0.01 micrometers and less than or equal to 50 micrometers, or greater than or equal to 0.01 micrometers and less than or equal to 20 micrometers). Other ranges are also possible.

[0151] The average flow orifice diameter of the filter medium can be determined according to ASTM F-316 (2003).

[0152] Filter media can have any suitable total Gurley stiffness (e.g., in the machine direction and / or in the transverse direction). For example, in some cases, the total Gurley stiffness of the filter media (e.g., in the machine direction and / or in the transverse direction) is greater than or equal to 1 mg, greater than or equal to 5 mg, greater than or equal to 10 mg, greater than or equal to 15 mg, greater than or equal to 20 mg, greater than or equal to 25 mg, greater than or equal to 50 mg, greater than or equal to 75 mg, greater than or equal to 100 mg, greater than or equal to 150 mg, greater than or equal to 200 mg, greater than or equal to 300 mg, greater than or equal to 400 mg, greater than or equal to 500 mg, greater than or equal to 750 mg, greater than or equal to 1000 mg, greater than or equal to 1500 mg, greater than or equal to 2000 mg, greater than or equal to 2500 mg, or greater than or equal to 3000 mg. In some embodiments, the total Gurley stiffness of the filter media (e.g., in the machine direction and / or in the transverse direction) is less than or equal to 3500 mg, less than or equal to 3250 mg, less than or equal to 3000 mg, less than or equal to 2750 mg, less than or equal to 2500 mg, less than or equal to 2250 mg, less than or equal to 2000 mg, less than or equal to 150 mg, less than or equal to 1000 mg, less than or equal to 750 mg, less than or equal to 500 mg, less than or equal to 400 mg, less than or equal to 300 mg, less than or equal to 200 mg, or less than or equal to 150 mg. Combinations of these ranges are also possible (e.g., greater than or equal to 1 mg and less than or equal to 3500 mg, greater than or equal to 10 mg and less than or equal to 3000 mg, or greater than or equal to 25 mg and less than or equal to 3000 mg). Other ranges are also possible.

[0153] The total Gurley stiffness of the filter media can be determined according to T543 om-94 (e.g., in the machine direction and / or in the transverse direction).

[0154] The filter media can have any suitable γ (e.g., at the most penetrating particle size (MPPS) or at 0.09 micrometers). For example, in some cases, the γ of the filter media (e.g., at MPPS or at 0.09 micrometers) is greater than or equal to 3, greater than or equal to 4, greater than or equal to 5, greater than or equal to 6, greater than or equal to 7, greater than or equal to 8, greater than or equal to 9, greater than or equal to 10, greater than or equal to 12, greater than or equal to 15, greater than or equal to 20, greater than or equal to 25, greater than or equal to 30, greater than or equal to 40, greater than or equal to 50, greater than or equal to 75, greater than or equal to 100, greater than or equal to 125, greater than or equal to 150, greater than or equal to 200, or greater than or equal to 250. In some cases, the gamma of the filter media (e.g., at MPPS or at 0.09 micrometers) is less than or equal to 400, less than or equal to 375, less than or equal to 350, less than or equal to 325, less than or equal to 300, less than or equal to 275, less than or equal to 250, less than or equal to 200, less than or equal to 150, less than or equal to 125, less than or equal to 100, less than or equal to 75, less than or equal to 50, less than or equal to 40, less than or equal to 30, or less than or equal to 25. Combinations of these ranges are also possible (e.g., greater than or equal to 3 and less than or equal to 300, or greater than or equal to 4 and less than or equal to 300). Other ranges are also possible.

[0155] γ is defined by the following formula: γ = (-log 10(Penetration % / 100) / (Average Pressure Drop, mm H2O) × 100. Penetration (usually expressed as a percentage) is defined as follows: Penetration (%) = (C / C0) * 100, where C is the particle concentration after passing through the filter, and C0 is the particle concentration before passing through the filter. Penetration (and γ) can be measured at any desired particle size (e.g., MPPS or 0.09 micrometers). MPPS penetration is the penetration rate for the most easily penetrated particle size; in other words, when measuring penetration for a range of particle sizes, MPPS penetration is the penetration value measured for the particle with the highest penetration rate. Penetration (e.g., MPPS penetration) and average pressure drop can be measured for any particle size using the EN1822:2009 standard for air filtration described below. Penetration and average pressure drop can be measured by blowing dioctyl phthalate (DOP) particles through a filter medium and measuring the percentage of particles that pass through the filter medium and the pressure drop when the particles are blown through the filter medium. This can be achieved based on the EN1822:2009 standard for MPPS DOP particles using a TSI 3160 automated filter test unit from TSI, Inc., equipped with a dioctyl phthalate generator for DOP aerosol testing. The TSI 3160 automated filter test unit is used to test DOP aerosols at a depth of 100 cm upstream of the filter media surface. 2 DOP particle groups with different average particle diameters were sequentially blown onto the surface area of ​​the filter media. The particle groups were blown onto the upstream surface of the filter media in order of increasing average diameter, each with a geometric standard deviation of less than 1.3, and having the following set of average diameters: 0.04 μm, 0.08 μm, 0.12 μm, 0.16 μm, 0.2 μm, 0.26 μm, and 0.3 μm. During the time period while the particle groups were being blown onto the upstream surface of the filter media, the penetration rate and average pressure drop were measured continuously and individually for each particle group. Upstream and downstream particle concentrations were measured using a cohesive particle counter. During the penetration rate measurement, a 100 cm² area was taken from the upstream surface of the filter media. 2 The surface area is subjected to a continuous load of DOP particles at an airflow of 12 L / min (generating a media surface velocity of 2 cm / s). Each particle group is blown upstream of the filter media surface for 120 seconds or at least 1000 particles are counted downstream of the filter media, whichever is longer.

[0156] To determine MPPS penetration, the instrument measures the penetration value across the filter medium (or layer) by determining the DOP particle size (i.e., the most penetrable particle size (MPPS)) at which the highest penetration level was measured. The sample is sequentially exposed to particles of each size. The particle penetration as a function of particle size is plotted, and the data is fitted with a parabolic function. The maximum value of the parabolic function is then found; the particle size at the maximum value is the MPPS, and the penetration at the maximum value is the penetration at that MPPS.

[0157] The filter media can have any suitable air permeability. For example, in some embodiments, the air permeability of the filter media is greater than or equal to 0.2 CFM, greater than or equal to 0.5 CFM, greater than or equal to 1 CFM, greater than or equal to 2 CFM, greater than or equal to 5 CFM, greater than or equal to 10 CFM, greater than or equal to 20 CFM, greater than or equal to 30 CFM, greater than or equal to 40 CFM, greater than or equal to 50 CFM, greater than or equal to 75 CFM, greater than or equal to 100 CFM, greater than or equal to 125 CFM, greater than or equal to 150 CFM, greater than or equal to 175 CFM, greater than or equal to 200 CFM, greater than or equal to 250 CFM, greater than or equal to 300 CFM, greater than or equal to 400 CFM, greater than or equal to 500 CFM, greater than or equal to 600 CFM, greater than or equal to 700 CFM, or greater than or equal to 800 CFM. In some embodiments, the air permeability of the filter media is less than or equal to 1000 CFM, less than or equal to 900 CFM, less than or equal to 800 CFM, less than or equal to 700 CFM, less than or equal to 600 CFM, less than or equal to 500 CFM, less than or equal to 400 CFM, less than or equal to 300 CFM, less than or equal to 250 CFM, less than or equal to 200 CFM, less than or equal to 175 CFM, less than or equal to 150 CFM, less than or equal to 125 CFM, less than or equal to 100 CFM, less than or equal to 75 CFM, less than or equal to 50 CFM, less than or equal to 40 CFM, or less than or equal to 30 CFM. Combinations of these ranges are also possible (e.g., greater than or equal to 0.2 CFM and less than or equal to 1000 CFM, or greater than or equal to 0.5 CFM and less than or equal to 800 CFM). Other ranges are also possible.

[0158] The air permeability of the filter medium can be determined according to ASTM D737-04 (2016) at a pressure of 125 Pa.

[0159] The filter media can have any suitable efficiency (e.g., initial efficiency). For example, in some embodiments, the efficiency (e.g., initial efficiency) of the filter media is greater than or equal to 1%, greater than or equal to 2%, greater than or equal to 5%, greater than or equal to 10%, greater than or equal to 20%, greater than or equal to 30%, greater than or equal to 40%, greater than or equal to 50%, greater than or equal to 60%, greater than or equal to 70%, greater than or equal to 80%, greater than or equal to 85%, greater than or equal to 90%, greater than or equal to 95%, greater than or equal to 97%, greater than or equal to 98%, greater than or equal to 99%, greater than or equal to 99.9%, greater than or equal to 99.99%, greater than or equal to 99.9999%, or greater than or equal to 99.99999%. In some implementations, the efficiency of the filter media is less than 100%, less than or equal to 99.99999%, less than or equal to 99.999%, less than or equal to 99.99%, less than or equal to 99.9%, less than or equal to 99.5%, less than or equal to 99%, less than or equal to 98%, less than or equal to 97%, less than or equal to 95%, less than or equal to 90%, less than or equal to 85%, or less than or equal to 80%. Combinations of these ranges are also possible (e.g., greater than or equal to 1% and less than 100%, greater than or equal to 2% and less than or equal to 99.99999%, or greater than or equal to 5% and less than or equal to 99.99999%). Other ranges are also possible.

[0160] Efficiency can be determined by the following equation: Efficiency (%) = 100 - Penetration (%), where the penetration is determined as described above for any particle size (e.g., at 0.09 micrometers).

[0161] The filter media can have any suitable salt (e.g., NaCl) loading capacity. For example, in some cases, the salt (e.g., NaCl) loading capacity of the filter media is greater than or equal to 0.1 g / m³. 2 ≥0.3 g / m 2 ≥0.5 g / m 2 ≥0.7 g / m 2 ≥1 g / m 2 ≥2 g / m 2 ≥3 g / m 2 ≥4 g / m 2 ≥5 g / m 2 ≥6 g / m 2 ≥7 g / m 2 ≥8 g / m 2≥9 g / m 2 ≥10 g / m 2 ≥12 g / m 2 ≥15 g / m 2 ≥20 g / m 2 ≥25 g / m 2 ≥30 g / m 2 or greater than or equal to 35 g / m 2 In some cases, the salt loading capacity (e.g., NaCl) of the filter media is less than or equal to 40 g / m³. 2 Less than or equal to 38 g / m 2 Less than or equal to 35 g / m 2 Less than or equal to 33 g / m 2 Less than or equal to 30 g / m 2 Less than or equal to 28 g / m 2 Less than or equal to 25 g / m 2 Less than or equal to 20 g / m 2 Less than or equal to 15 g / m 2 Less than or equal to 10 g / m 2 Less than or equal to 5g / m 2 Less than or equal to 4 g / m 2 Less than or equal to 3 g / m 2 Less than or equal to 2 g / m 2 or less than or equal to 1 g / m 2 Combinations of these ranges are also possible (e.g., greater than or equal to 0.1 g / m³). 2 And less than or equal to 40 g / m 2 or greater than or equal to 0.5 g / m 2 And less than or equal to 30 g / m 2 Other ranges are also possible.

[0162] The salt (e.g., NaCl) loading capacity of the filter media can be determined by increasing the nominal exposure area to 100 cm². 2 The filter media was exposed to 15 mg / m 3The concentration and median diameter of salt (e.g., NaCl) particles at a face velocity of 5.3 cm / s were determined. The salt (e.g., NaCl) load was determined using an 8130 CertiTest™ automated filter testing unit from TSI, Inc., equipped with a salt (e.g., NaCl) generator. The average particle size generated by the salt particle generator was a mass-average diameter of 0.26 micrometers. The 8130 operated in continuous mode, with a pressure drop read approximately one per minute. A 100 cm⁻¹ pressure drop was used. 2 Filter media sample, containing 15 mg / m 3 The test was run at a flow rate of 32 liters per minute (area velocity of 5.3 cm / s) of salt (e.g., NaCl) until the pressure drop across the filter media increased by 250 Pa. The salt (e.g., NaCl) loading capacity was determined by weighing the filter media before and after the test and adding the measured mass to the area of ​​the filter media to obtain the salt (e.g., NaCl) loading capacity per unit area of ​​the filter media.

[0163] The filter media can have any suitable DOP oil loading capacity. For example, in some embodiments, the filter media has a DOP oil loading capacity greater than or equal to 1 g / m³. 2 ≥2 g / m 2 ≥3 g / m 2 ≥4 g / m 2 ≥5 g / m 2 ≥7 g / m 2 ≥10 g / m 2 ≥12 g / m 2 ≥15 g / m 2 ≥20 g / m 2 ≥30 g / m 2 ≥40 g / m 2 ≥50 g / m 2 ≥60 g / m 2 or greater than or equal to 70 g / m 2 In some implementations, the DOP oil loading capacity of the filter media is less than or equal to 80 g / m³. 2 Less than or equal to 75 g / m 2 Less than or equal to 70 g / m 2 Less than or equal to 65 g / m 2 Less than or equal to 60 g / m 2 Less than or equal to 55 g / m 2 Less than or equal to 50 g / m2 Less than or equal to 40 g / m 2 Less than or equal to 30 g / m 2 Less than or equal to 20 g / m 2 Less than or equal to 15 g / m 2 Less than or equal to 12 g / m 2 Less than or equal to 10 g / m 2 Less than or equal to 7 g / m 2 Or less than or equal to 6 g / m 2 Combinations of these ranges are also possible (e.g., greater than or equal to 1 g / m³). 2 And less than or equal to 80 g / m 2 ≥3 g / m 2 And less than or equal to 70 g / m 2 or greater than or equal to 4 g / m 2 And less than or equal to 70 g / m 2 Other ranges are also possible.

[0164] Typically, the DOP oil loading process involves filling the filter media with 100 cm of oil. 2 The test area was exposed to a concentration of 80 mg / m² 3 Up to 100 mg / m 3 The process involves an aerosol of DOP particles at a flow rate of 32 L / min and a surface velocity of 5.32 cm / s. The DOP particles are generated by a TDA 100P aerosol generator available from Air Techniques International, and have a median count diameter of 0.18 μm, a mass-average diameter of 0.3 μm, and a geometric standard deviation of less than 1.6 μm. Depending on the specific test, different filter media characteristics can be determined by performing one or more measurements continuously or by pausing the DOP oil load during the DOP oil load. For example, the pressure drop across the filter media as a function of the DOP oil load can be continuously measured. The DOP oil load, or DOP weight, per filter media area can be determined by measuring the pressure drop during the DOP oil load, stopping the oil load after the pressure drop doubles, and then weighing the filter media. Any increase in the filter media weight is attributed to the DOP oil, and therefore the DOP oil load is determined by taking the difference between the measured weight and the initial weight of the filter media without DOP. Other parameters (e.g., penetration rate at MPPS, γ) can also be determined during or after DOP oil loading by performing measurements as described herein.

[0165] In some embodiments, the filter media as a whole (e.g., comprising one or more layers having oleophobic properties, such as containing oleophobic components, one or more layers having an oil grade greater than or equal to 1, and / or one or more surface-modified layers) can perform particularly well after undergoing a DOP oil loading process. Such performance characteristics may include: a relatively low pressure drop after undergoing a DOP oil loading process; a relatively low change in pressure drop after undergoing a DOP oil loading process compared to the same media before the DOP oil loading process; a relatively low permeability at MPPS after undergoing a DOP oil loading process; a relatively low change in permeability at MPPS after undergoing a DOP oil loading process compared to the same media before the DOP oil loading process; a high γ value after undergoing a DOP oil loading process; and / or a relatively low change in γ value after undergoing a DOP oil loading process compared to the same media before the DOP oil loading process.

[0166] As described above, the surface of the surface-treated fiber web described herein can be treated using any of a variety of suitable techniques. For example, in some embodiments, the surface-treated fiber web is fluid-reinforced. A fluid-reinforced surface-treated fiber web may have one or more structural features indicating fluid reinforcement. Such structural features may include cavities and / or entangled fibers (e.g., fibers entangled via a fluid reinforcement process). The structural features may be homogeneous or non-homogeneous. Similarly, the structural features may be isotropic or anisotropic.

[0167] According to some embodiments, the surface-treated fiber web described herein can be prepared by fluid-reinforcing a precursor layer. The fluid-reinforcing surface-treated fiber web and / or layer can be fluid-reinforcing on one side or on both opposite sides. The filter medium can also comprise two or more fluid-reinforcing surface-treated fiber webs and / or layers. Such layers can be fluid-reinforcing individually and then combined (e.g., via lamination), or they can be fluid-reinforcing after combination. One or more layers can also be fluid-reinforcing during formation (e.g., during wet web forming). When two fluid-reinforcing layers, each fluid-reinforcing exactly on one side, are combined, the two fluid-reinforcing sides can face each other, face away from each other, or face the same direction. In some embodiments, the filter medium comprises exactly one fluid-reinforcing surface-treated fiber web or layer, and / or comprises both a fluid-reinforcing surface-treated fiber web or layer and another unreinforcing layer.

[0168] Fluid enhancement can include impinging a jet and / or flow of fluid onto a surface-treated fiber web. In some embodiments, fluid enhancement includes performing a hydraulic entanglement process (i.e., the fluid may include liquid water, and the process may cause the fibers in the layer to become entangled). Fluid enhancement can also include performing a process that is otherwise identical to the hydraulic entanglement process but is carried out at too low a pressure to cause hydraulic entanglement, and / or performing a process similar to hydraulic entanglement but using a fluid other than liquid water (e.g., a liquid or gas other than water). Non-limiting examples of suitable fluids for performing fluid enhancement include liquid water, steam, and compressed air.

[0169] The jets and / or flows of fluid used in the fluid enhancement process can be provided from a variety of suitable sources, such as hydraulic entanglement devices and / or sprayers. In some embodiments, the jets and / or flows of fluid comprise droplets (e.g., they may be in the form of a spray). The fluid impinging on the surface-treated fiber web can be relatively pure; for example, it can be distilled water and / or deionized water. After fluid enhancement, the surface-treated fiber web can be dried, for example, using an air dryer. In some embodiments, the surface-treated fiber web is subjected to fluid enhancement while being moved laterally. The surface-treated fiber web can be conveyed on a porous belt, such as a screen or mesh conveyor belt. While being conveyed on the porous belt, it can be exposed to jets and / or flows of fluid, which can first be pressurized by a pump. These jets and / or flows can be stationary and / or moving. The fluid jets and / or flows can impinge on and / or penetrate the surface-treated fiber web. In some implementations, a vacuum is provided beneath the porous conveyor belt, which can facilitate the flow of fluid through the surface-treated fiber web and / or reduce the time and amount of energy required to dry the layer at the end of the fluid reinforcement process.

[0170] The surface-treated fiber web can also be fluid-enhanced while stationary. In such an embodiment, the nozzle supplying the fluid jet and / or flow can move above the surface-treated fiber web at various speeds and / or in various patterns.

[0171] In some implementations, the nozzle can be opened and closed during fluid enhancement.

[0172] In some implementations, filter media components, such as adsorbent particles or additional layers, are deposited such that they are at least partially disposed on a fluid-reinforced, surface-treated fiber web.

[0173] In some implementations, careful selection of fluid reinforcement process parameters can be used to surface-treat the surface of the fiber web to include a plurality of cavities with advantageous morphology, as discussed in more detail below.

[0174] The fluid enhancement process may include impinging a jet and / or flow of fluid having any of a plurality of suitable pressures onto a surface-treated fiber web. In some embodiments, the hydraulic entanglement process includes impinging a jet and / or flow of fluid having the following pressures onto a surface-treated fiber web: greater than or equal to 0.5 bar, greater than or equal to 0.7 bar, greater than or equal to 1 bar, greater than or equal to 1.2 bar, greater than or equal to 1.5 bar, greater than or equal to 2 bar, greater than or equal to 2.5 bar, greater than or equal to 3 bar, greater than or equal to 5 bar, greater than or equal to 10 bar, greater than or equal to 15 bar, greater than or equal to 20 bar, greater than or equal to 25 bar, greater than or equal to 30 bar, greater than or equal to 35 bar, or greater than or equal to 40 bar. In some embodiments, the fluid enhancement process includes impinging a jet and / or flow of fluid having the following pressures onto a surface-treated fiber mesh: less than or equal to 50 bar, less than or equal to 40 bar, less than or equal to 35 bar, less than or equal to 30 bar, less than or equal to 25 bar, less than or equal to 20 bar, less than or equal to 15 bar, less than or equal to 10 bar, less than or equal to 5 bar, less than or equal to 3 bar, less than or equal to 2.5 bar, less than or equal to 2 bar, less than or equal to 1.5 bar, less than or equal to 1.2 bar, less than or equal to 1 bar, or less than or equal to 0.7 bar. Combinations of the above ranges are also possible (e.g., greater than or equal to 0.5 bar and less than or equal to 50 bar, greater than or equal to 0.5 bar and less than or equal to 40 bar, or greater than or equal to 0.5 bar and less than or equal to 30 bar, or greater than or equal to 10 bar and less than or equal to 20 bar). Other ranges are also possible.

[0175] In some implementations, each jet and / or flow of fluid may independently have a pressure within one or more of the aforementioned ranges. The pressure of each pair of jets and / or flows of fluid may be the same or different.

[0176] In some embodiments, a device suitable for fluid enhancement (e.g., a hydraulic entanglement device) may include a plurality of nozzles configured to jet and / or flow pressurized fluid over a surface-treated fiber web as described herein. Similarly, fluid enhancement may include impinging a jet and / or flow of pressurized fluid from nozzles present in the fluid enhancement device onto a layer (e.g., a surface-treated fiber web). The plurality of nozzles may have any of a variety of spatial positions relative to each other. For example, the plurality of nozzles may be arranged in one or more stations. Each station may include exactly one row, or may include multiple rows. In some embodiments, the nozzles in the rows and / or stations are regularly spaced; however, an irregularly spaced arrangement of some or all nozzles is also possible. The hydraulic entanglement device may also include some regularly spaced nozzles and some irregularly spaced nozzles. It should also be noted that different nozzles and / or different stations may have the same characteristics (e.g., pressure, nozzle diameter) as other nozzles and / or stations, or may have different characteristics than other nozzles and / or stations.

[0177] In some implementations, the nozzle orifice density of the fluid enhancement device is greater than or equal to 50 nozzle orifices / m, greater than or equal to 100 nozzle orifices / m, greater than or equal to 150 nozzle orifices / m, greater than or equal to 200 nozzle orifices / m, greater than or equal to 250 nozzle orifices / m, greater than or equal to 300 nozzle orifices / m, greater than or equal to 400 nozzle orifices / m, greater than or equal to 500 nozzle orifices / m, greater than or equal to 700 nozzle orifices / m, greater than or equal to 1000 nozzle orifices / m, greater than or equal to 1500 nozzle orifices / m, greater than or equal to 2000 nozzle orifices / m, greater than or equal to 3000 nozzle orifices / m, or greater than or equal to 5000 nozzle orifices / m. Nozzle orifice / meter, greater than or equal to 10,000 nozzle orifices / meter, greater than or equal to 20,000 nozzle orifices / meter, greater than or equal to 30,000 nozzle orifices / meter, greater than or equal to 40,000 nozzle orifices / meter, greater than or equal to 50,000 nozzle orifices / meter, greater than or equal to 60,000 nozzle orifices / meter, greater than or equal to 70,000 nozzle orifices / meter, greater than or equal to 80,000 nozzle orifices / meter, greater than or equal to 90,000 nozzle orifices / meter, greater than or equal to 100,000 nozzle orifices / meter, greater than or equal to 125,000 nozzle orifices / meter, greater than or equal to 150,000 nozzle orifices / meter, or greater than or equal to 175,000 nozzle orifices / meter. In some implementations, the nozzle number density of the fluid enhancement device is less than or equal to 200,000 nozzle orifices / meter, less than or equal to 175,000 nozzle orifices / meter, less than or equal to 150,000 nozzle orifices / meter, less than or equal to 125,000 nozzle orifices / meter, less than or equal to 100,000 nozzle orifices / meter, less than or equal to 90,000 nozzle orifices / meter, less than or equal to 80,000 nozzle orifices / meter, less than or equal to 70,000 nozzle orifices / meter, less than or equal to 60,000 nozzle orifices / meter, less than or equal to 50,000 nozzle orifices / meter, less than or equal to 40,000 nozzle orifices / meter, less than or equal to 30,000 nozzle orifices / meter, less than or equal to... Equal to 20,000 nozzle holes / meter, less than or equal to 10,000 nozzle holes / meter, less than or equal to 5,000 nozzle holes / meter, less than or equal to 3,000 nozzle holes / meter, less than or equal to 2,000 nozzle holes / meter, less than or equal to 1,500 nozzle holes / meter, less than or equal to 1,000 nozzle holes / meter, less than or equal to 700 nozzle holes / meter, less than or equal to 500 nozzle holes / meter, less than or equal to 400 nozzle holes / meter, less than or equal to 300 nozzle holes / meter, less than or equal to 250 nozzle holes / meter, less than or equal to 200 nozzle holes / meter, less than or equal to 150 nozzle holes / meter, or less than or equal to 100 nozzle holes / meter.Combinations of the above ranges are also possible (e.g., greater than or equal to 50 nozzle orifices / meter and less than or equal to 150,000 nozzle orifices / meter, greater than or equal to 100 nozzle orifices / meter and less than or equal to 100,000 nozzle orifices / meter, or greater than or equal to 200 nozzle orifices / meter and less than or equal to 50,000 nozzle orifices / meter). Other ranges are also possible.

[0178] The fluid enhancement apparatus described herein (e.g., a hydraulic entanglement apparatus) may include nozzles having any of a plurality of suitable nozzle orifice diameters. Furthermore, fluid enhancement may include impinging a jet and / or flow of pressurized fluid from nozzles present in the fluid enhancement apparatus onto a layer (e.g., a surface-treated fiber web). In some embodiments, the fluid enhancement apparatus includes nozzles having nozzle orifice diameters greater than or equal to 1 micrometer, greater than or equal to 5 micrometers, greater than or equal to 10 micrometers, greater than or equal to 20 micrometers, greater than or equal to 30 micrometers, greater than or equal to 40 micrometers, greater than or equal to 50 micrometers, greater than or equal to 75 micrometers, greater than or equal to 100 micrometers, greater than or equal to 150 micrometers, greater than or equal to 200 micrometers, greater than or equal to 250 micrometers, greater than or equal to 300 micrometers, greater than or equal to 350 micrometers, greater than or equal to 400 micrometers, greater than or equal to 500 micrometers, greater than or equal to 600 micrometers, greater than or equal to 700 micrometers, greater than or equal to 800 micrometers, or greater than or equal to 900 micrometers. In some embodiments, the fluid enhancement device includes nozzles having the following nozzle orifice diameters: less than or equal to 1000 micrometers, less than or equal to 900 micrometers, less than or equal to 800 micrometers, less than or equal to 700 micrometers, less than or equal to 600 micrometers, less than or equal to 500 micrometers, less than or equal to 400 micrometers, less than or equal to 350 micrometers, less than or equal to 300 micrometers, less than or equal to 250 micrometers, less than or equal to 200 micrometers, less than or equal to 150 micrometers, less than or equal to 100 micrometers, less than or equal to 75 micrometers, less than or equal to 50 micrometers, less than or equal to 40 micrometers, less than or equal to 30 micrometers, less than or equal to 20 micrometers, less than or equal to 10 micrometers, or less than or equal to 5 micrometers. Combinations of the above ranges are also possible (e.g., greater than or equal to 1 micrometer and less than or equal to 1000 micrometers, greater than or equal to 5 micrometers and less than or equal to 500 micrometers, or greater than or equal to 50 micrometers and less than or equal to 300 micrometers). Other ranges are also possible.

[0179] In some embodiments, each of the plurality of nozzles in the fluid enhancement device may independently have a nozzle orifice diameter within one or more of the ranges described above. The diameters of each pair of nozzles may be the same or different.

[0180] In an embodiment where a fluid-enhanced surface-treated fiber web is being translated (e.g., a surface-treated fiber web), the surface-treated fiber web can be translated at any suitable speed. In some embodiments, the surface-treated fiber web can be translated at speeds of: greater than or equal to 1 m / min, greater than or equal to 2 m / min, greater than or equal to 3 m / min, greater than or equal to 4 m / min, greater than or equal to 5 m / min, greater than or equal to 10 m / min, greater than or equal to 20 m / min, greater than or equal to 30 m / min, greater than or equal to 40 m / min, greater than or equal to 50 m / min, greater than or equal to 75 m / min, greater than or equal to 100 m / min, greater than or equal to 150 m / min, greater than or equal to 300 m / min, greater than or equal to 400 m / min, greater than or equal to 500 m / min, greater than or equal to 750 m / min, greater than or equal to 1000 m / min, greater than or equal to 1500 m / min, or greater than or equal to 2000 m / min. In some embodiments, the surface-treated fiber web undergoing fluid reinforcement translates at the following speeds: less than or equal to 2500 m / min, less than or equal to 2000 m / min, less than or equal to 1500 m / min, less than or equal to 1000 m / min, less than or equal to 750 m / min, less than or equal to 500 m / min, less than or equal to 400 m / min, less than or equal to 300 m / min, less than or equal to 250 m / min, less than or equal to 200 m / min, less than or equal to 150 m / min, less than or equal to 100 m / min, less than or equal to 75 m / min, less than or equal to 50 m / min, less than or equal to 40 m / min, less than or equal to 30 m / min, less than or equal to 20 m / min, less than or equal to 10 m / min, less than or equal to 5 m / min, less than or equal to 4 m / min, less than or equal to 3 m / min, or less than or equal to 2 m / min. Combinations of the above ranges are also possible (e.g., greater than or equal to 1 m / min and less than or equal to 2500 m / min, greater than or equal to 2 m / min and less than or equal to 500 m / min, or greater than or equal to 3 m / min and less than or equal to 150 m / min). Other ranges are also possible.

[0181] The filter media described herein can be used in any of a variety of applications. In some embodiments, the filter media is an air filter. For example, in some cases, the filter media is a high-efficiency particulate air (HEPA) filter or an ultra-low penetration air (ULPA) filter. In some embodiments, the filter media is a cabin filter (e.g., a filter for an air chamber). According to some embodiments, the described filter media is part of respiratory protective equipment, such as a face mask (e.g., a pleated face mask), a ventilator, and / or an electrically powered respiratory protective device (PRPE). In some embodiments, the filter media can be used in gas turbine filters. In some embodiments, the filter media is used in cleanrooms (e.g., for the removal of gaseous molecular contaminants (AMC)). In some embodiments, the filter media is used in fuel cells. According to some embodiments, the filter media is used for HVAC filtration. Filter media containing adsorbent particles can be particularly useful for use in cleanrooms (e.g., for the removal of AMC), in fuel cells, and for indoor air purification.

[0182] The following examples are intended to illustrate certain implementations of this disclosure, but do not represent the full scope of this disclosure.

[0183] Example 1

[0184] This embodiment demonstrates the morphology improvement resulting from surface treatment of the fiber web suitable for use as a filter medium in a non-limiting embodiment. Two identical backings were prepared. The backings comprised a surface-treated fiber web containing 100% by weight of synthetic fibers. The backings were identical except that in sample backing 1 (SB1), the backing was fluid-reinforced to improve its cavity morphology, while control backing 1 (CB1) comprised an unreinforced backing.

[0185] The morphology was measured using the Mate Gauge laser system, which can be used to determine the type of cavity frequency in the lateral dimension described elsewhere in this paper. Figure 4 The relative heights of the top and bottom of the SB1 backing at a 175 cm section of the backing are shown. Figure 5 The relative heights of the top and bottom portions of the CB1 backing at a comparable 175 cm section of the backing are shown. As illustrated, as per... Figure 4 The presence of a large number of peaks at both the top and bottom of the backing, as shown, confirms this relative to... Figure 5 The number of peaks observed in the CB1 backing cross-section (lateral dimension cavity frequencies: 1929 cavities / m) is shown, while the SB1 backing includes a much higher number of lateral dimension cavity frequencies (4015 cavities / m). However, visual inspection indicates that... Figure 4 The cavities of the SB1 backing are smaller than Figure 5 The individual cavities of the CB1 backing. Therefore, the improved performance of the SB1 backing (as reported in Example 1) is achieved through visual inspection. Figure 4 The increased surface area observed in the SB1 backing, and the relatively small cavity size for the reasons mentioned above, are both caused by this.

[0186] Example 2

[0187] This embodiment compares the cavity dimensions of backing SB1 and CB1 described in Embodiment 1. This is achieved by processing the 1300 × 1300 micrometer surface measured at 210x magnification. 2 Partial SEM images were used to measure cavity dimensions. The SEM images were processed using ImageJ for cavity analysis according to the method described above, with a threshold of 50. Given the minimum resolution of the image, the cavity size was determined for areas larger than 10 micrometers. 2 The characteristics of a plurality of cavities with a specified minimum cutoff area were analyzed to determine their properties. Table 2 reports the number and average area of ​​different cavity groups to characterize the cavity size distribution of SB1 and compares them with the cavity size distribution of CB1.

[0188]

[0189] As shown in Table 2, the backing of SB1 contains significantly more cavities compared to the backing of CB1. However, a significantly smaller proportion of the cavities in SB1 are classified as large cavities, and the average size of the large cavities, as well as the average size of the medium and large cavities together, are both significantly smaller after fluid reinforcement of the backing. Therefore, this embodiment provides further evidence of the morphological improvement of the backing caused by fluid reinforcement.

[0190] Example 3

[0191] This embodiment compares the interfacial area ratios of SB1 and CB1 as described in Embodiment 1. The interfacial area ratio of each backing was determined using the method described above. The interfacial area ratio of SB1 is 0.710, while the interfacial area ratio of CB1 is 0.305. Therefore, this embodiment provides further evidence of morphological improvement of the backing caused by fluid entanglement.

[0192] While several embodiments of this disclosure have been described and illustrated herein, those skilled in the art will readily contemplate a variety of other ways and / or structures for performing the functions described herein and / or obtaining the results and / or one or more advantages described herein, and each such variation and / or modification is considered to be within the scope of this disclosure. More generally, those skilled in the art will readily understand that all parameters, dimensions, materials, and configurations described herein are intended to be exemplary, and actual parameters, dimensions, materials, and / or configurations will depend on the specific application of the teachings of this disclosure. Those skilled in the art will recognize or be able to determine many equivalents of the specific embodiments of the disclosure described herein using only conventional experimentation. Therefore, it should be understood that the foregoing embodiments are presented by way of example only, and that this disclosure can be practiced in ways other than those specifically described and claimed within the scope of the appended claims and their equivalents. This disclosure relates to each individual feature, system, article of manufacture, material, and / or method described herein. Furthermore, any combination of two or more such features, systems, articles of manufacture, materials, and / or methods is included within the scope of this disclosure if such features, systems, articles of manufacture, materials, and / or methods are not inconsistent with each other.

[0193] Unless explicitly stated otherwise, nouns without quantifiers as used herein in the specification and claims shall be understood to mean “at least one / a kind”.

[0194] The phrase “and / or” as used herein in the specification and claims should be understood to mean “any one or both” of the elements so combined, i.e., elements that coexist in some cases and exist separately in others. Unless explicitly stated to the contrary, other elements may optionally exist besides those specifically indicated by the “and / or” clause, whether related to or unrelated to those specifically indicated. Thus, as a non-limiting example, when used in conjunction with open-ended language such as “comprising / including,” reference to “A and / or B” may in one embodiment refer to A without B (optionally including elements other than B); in another embodiment, refer to B without A (optionally including elements other than A); in yet another embodiment, refer to both A and B (optionally including other elements); and so on.

[0195] As used herein in the specification and claims, “or” should be understood to have the same meaning as “and / or” as defined above. For example, when separating items in a list, “or” or “and / or” should be understood to be inclusive, i.e., including multiple elements or at least one of the elements in the list, but also including more than one of them, and optionally including other unlisted items. Only when the opposite terms are explicitly stated, such as “only one” or “exact one”, or when used in the claims, “consisting of” means including multiple elements or exactly one of the elements in the list. Generally, when preceded by exclusive terms such as “one of,” “one of,” “only one of,” or “exact one of,” the term “or” as used herein should only be interpreted to indicate an exclusive choice (i.e., “one or another but not two”). When used in the claims, “consisting substantially of” should have its ordinary meaning as used in the field of patent law.

[0196] As used herein in the specification and claims, the phrase "at least one" when referring to a list of one or more elements should be understood to mean at least one element selected from any one or more elements in the list, but does not necessarily include all elements specifically listed in the list and at least one of each element, and does not exclude any combination of elements in the list. This definition also allows for the optional presence of elements other than those specifically indicated in the list of elements referred to by the phrase "at least one," whether related to or unrelated to those specifically indicated elements. Therefore, as a non-limiting example, "at least one of A and B" (or equivalently, "at least one of A or B", or equivalently, "at least one of A and / or B"), in one embodiment, may refer to at least one A, optionally including more than one A, while B is absent (and optionally including elements other than B); in another embodiment, may refer to at least one B, optionally including more than one B, while A is absent (and optionally including elements other than A); in yet another embodiment, may refer to at least one A, optionally including more than one A, and at least one B, optionally including more than one B (and optionally including other elements); and so on.

[0197] As used in this article, "weight%" is an abbreviation for weight percentage. As used in this article, "atomic%" is an abbreviation for atomic percentage.

[0198] Some implementations may be embodied as methods, in which various embodiments have been described. Actions performed as part of the methods may be ordered in any suitable manner. Thus, implementations in which actions are performed in a different order than those shown may be constructed, which may include actions that differ from those described (e.g., more or fewer), and / or may involve performing some actions simultaneously, even if these actions are shown as being performed sequentially in the implementations specifically described above.

[0199] The use of ordinal terms such as "first," "second," "third," etc., to modify claim elements in claims does not imply any priority, order of precedence, or sequence of actions of one claim element relative to another claim element, or the chronological order of the actions of the method of execution. Rather, it is merely used as a marker to distinguish one claim element with a certain name from another element with the same name (but using ordinal terms), thereby differentiating claim elements.

[0200] In the claims and the foregoing description, all transitional phrases such as “comprising,” “including,” “with,” “having,” “containing,” “involving,” “holding,” etc., shall be understood as open-ended, that is, meaning including but not limited to. As set forth in Section 2111.03 of the Patent Examination Procedure Manual of the United States Patent and Trademark Office, only the transitional phrases “consisting of” and “consisting substantially of” shall be closed or semi-closed transitional phrases, respectively.

Claims

1. A filter medium, comprising: Fiber web, the fiber web comprising a plurality of surface cavities, wherein: The average length of the synthetic fibers in the fiber web is less than or equal to 40 mm. The unfolded interface area ratio of the fiber web is greater than or equal to 0.1, and The cavities of the fiber web have an average transverse dimensional frequency greater than or equal to 3,000 surface cavities / meter, and Multiple adsorbent particles are disposed on the fiber web.

2. The filter medium according to any of the preceding claims, wherein the filter medium comprises a plurality of adsorbent particles disposed on a nonwoven fiber web.

3. The filter medium according to any of the preceding claims, wherein the fiber web is nonwoven.

4. The filter medium according to any of the preceding claims, wherein the medium and large cavities among the plurality of cavities together have a size of less than or equal to 500 micrometers. 2 The average area.

5. The filter medium according to any of the preceding claims, wherein the largest cavity among the plurality of cavities has a size of less than or equal to 1300 micrometers. 2 The average area.

6. The filter medium according to any of the preceding claims, wherein the matrix polymer comprises only polymers with a molecular weight greater than 3 kDa.

7. The filter medium according to any of the preceding claims, wherein the plurality of adsorbent particles are a plurality of carbon particles.

8. The filter medium according to any of the preceding claims, wherein the adsorbent particles are at least partially disposed within the cavities of the plurality of cavities.

9. The filter medium according to any of the preceding claims, wherein the fiber web is a first layer of the filter medium, and the adsorbent particles form a second layer disposed on top of the first layer.

10. A method of manufacturing a filter medium according to any of the preceding claims, comprising first preparing a precursor fiber web, and fluidically reinforcing the precursor fiber web to produce a fiber web according to any of the preceding claims.

11. The method of claim 10, further comprising depositing a layer on the fiber web.

12. The filter medium according to any of the preceding claims further comprises at least a portion of an additional layer disposed on the fiber web.

13. The filter medium according to any of the preceding claims, wherein the additional layer comprises a fiber web.

14. The filter medium according to any of the preceding claims, wherein the fiber web of the additional layer comprises a plurality of glass fibers.

15. The filter medium according to any of the preceding claims, wherein at least some adsorbent particles are disposed within the fiber web.

Images