Filter media comprising water repellent additives and / or fibrillated fibers

Abstract

Filter media comprising water repellent additives and / or fibrillated fibers are generally provided. In some embodiments, the filter media comprises fibrillated fibers, such as lyocell fibers. In some embodiments, the filter media comprises water repellent additives, such as fluorinated water repellent additives and / or water repellent additives having minimal or no fluorine atoms. The filter media disclosed herein can comprise fluorinated water repellent additives but not water repellent additives having minimal or no fluorine atoms, can comprise water repellent additives having minimal or no fluorine atoms but not fluorinated water repellent additives, or comprise both fluorinated water repellent additives and water repellent additives having minimal or no fluorine atoms.

Description

[0001] Related applications

[0002] This application claims priority to U.S. Provisional Patent Application No. 63 / 569,526, filed March 25, 2024, entitled “FilterMedia Comprising Water-Repellent Additives and / or Fibrillated Fibers”, pursuant to 35 USC § 119(e), which is incorporated herein by reference in its entirety for all purposes. Technical Field

[0003] The present invention relates generally to filter media, and more specifically to filter media comprising water-repellent additives and / or fibrillated fibers. Background Technology

[0004] Filter media can be used in a variety of applications to remove contaminants from fluids.

[0005] Some filter media contain synthetic fibers, such as synthetic fibers containing poly(vinyl alcohol). However, in some cases, the use of synthetic fibers containing poly(vinyl alcohol) may lead to a decrease in performance (e.g., γ). Conversely, in some cases, filter media that do not contain synthetic fibers containing poly(vinyl alcohol) may result in a decrease in the wet strength and / or processability of the filter media.

[0006] Some filter media contain fluorinated water repellents. Compared to filter media containing non-fluorinated water repellents, some filter media containing fluorinated water repellents may have improved performance (e.g., higher gamma). However, new regulations may make some of these water repellents difficult to use.

[0007] Therefore, improved filter media design is needed. Summary of the Invention

[0008] The filter media, related components, and related methods are generally described.

[0009] In some embodiments, a filter medium is provided. According to some embodiments, the filter medium includes a nonwoven fiber web and a water-repellent additive, wherein the nonwoven fiber web comprises fine microglass fibers, microglass fibers of medium diameter, coarse glass fibers, and fibrillated fibers; wherein the average fiber diameter of the fine microglass fibers is less than or equal to 1 micrometer; wherein the average fiber diameter of the microglass fibers of medium diameter is greater than 1 micrometer and less than or equal to 6 micrometers; wherein the average fiber diameter of the coarse glass fibers is greater than 6 micrometers; and wherein the nonwoven fiber web comprises greater than 0% by weight and less than or equal to 20% by weight of fibrillated fibers.

[0010] Other advantages and novel features of the invention will become apparent from the following detailed description of various non-limiting embodiments of the invention when considered in conjunction with the accompanying drawings. Where this specification and any documents incorporated by reference contain conflicting and / or inconsistent disclosures, this specification shall prevail. If two or more documents incorporated by reference contain disclosures that conflict and / or are inconsistent with each other, the document with the later effective date shall prevail. Attached Figure Description

[0011] Non-limiting embodiments of the invention will be described by way of example with reference to the accompanying drawings, which are schematic and not intended to be drawn to scale. In the drawings, each identical or substantially identical component shown is generally denoted by the same reference numeral. For clarity, not every component is labeled in every drawing, nor is every component of every embodiment of the invention shown, unless illustration is required for understanding the invention by one of ordinary skill in the art. In the drawings:

[0012] Figure 1A A filter medium comprising a nonwoven fiber web is shown according to some embodiments;

[0013] Figure 1B A filter medium comprising a nonwoven fiber web and layers is shown according to some embodiments;

[0014] Figure 2A , Figure 2B and Figure 2C A system for determining the wet strength of a nonwoven fiber web, according to some embodiments, is shown;

[0015] Figure 3 The γ values ​​of various filter media according to some embodiments are shown;

[0016] Figure 4 , Figure 5 , Figure 6 and Figure 7 The water repellency values ​​of various filter media according to some implementation schemes are shown;

[0017] Figure 8 and Figure 9 The oil grade values ​​for various filter media according to some implementation schemes are shown;

[0018] Figure 10 Photographs of various filter media according to some implementation schemes are shown;

[0019] Figure 11 The poly(urethane) wicking height of various filter media according to some embodiments is shown;

[0020] Figure 12 and Figure 13The saturation pressure drop and average oil carryover value of various filter media according to some embodiments are shown.

[0021] Figure 14 It is a graph showing γ as a function of the amount of PVOH fibers present in a nonwoven fiber web sample, based on some implementation schemes;

[0022] Figure 15 It is a graph showing γ as a function of CSF of fibrillated lyocell fibers present in a nonwoven fiber web sample, according to some implementation schemes.

[0023] Figure 16 It is a graph based on some implementation schemes, where γ is a function of the amount of fibrillated lyocell fibers present in the nonwoven fiber web sample. Detailed Implementation

[0024] Filter media comprising water-repellent additives and / or fibrillated fibers are generally disclosed. In some embodiments, the filter media comprises a nonwoven fiber web comprising fibrillated fibers. As described herein, some nonwoven fiber webs comprising fibrillated fibers can exhibit improved properties compared to nonwoven fiber webs without fibrillated fibers, nonwoven fiber webs having an amount of fibrillated fibers beyond the scope of this disclosure, and / or nonwoven fiber webs having a fibrillation level beyond the scope of this disclosure. For example, in some embodiments, a nonwoven fiber web comprising an amount of fibrillated fibers (e.g., lyocell fibers) within the scope of this disclosure has reduced flammability, increased strength (e.g., wet strength), increased flexibility, increased processability, and / or improved performance (e.g., γ-rays) compared to a nonwoven fiber web with all other factors being equal, but with the fibrillated fiber (e.g., lyocell fibers) exceeding the scope of this disclosure. As another example, in some implementations, nonwoven fiber webs containing fibrillated fibers (e.g., lyocell fibers) with fibrillated fibers (e.g., lyocell fibers) within the scope of this disclosure have improved performance (e.g., γ) compared to nonwoven fiber webs containing fibrillated fibers (e.g., lyocell fibers) with the same fibrillation level beyond the scope of this disclosure.

[0025] In some embodiments, the filter media comprises water-repellent additives. Generally, filter media comprising fluorinated water-repellent additives and / or water-repellent additives having minimal or no fluorine atoms are provided. The filter media disclosed herein may comprise fluorinated water-repellent additives without comprising water-repellent additives having minimal or no fluorine atoms, comprise water-repellent additives having minimal or no fluorine atoms without comprising fluorinated water-repellent additives, or comprise both fluorinated water-repellent additives and water-repellent additives having minimal or no fluorine atoms.

[0026] In some embodiments, the filter media comprises a fluorinated water-repellent additive, which is a polymer, oligomer, or monomer that can and / or is configured to undergo a polymerization reaction to form a fluorinated polymer and / or oligomer. For example, the filter media may comprise perfluoropoly(ether), oligomeric perfluoroether, and / or monomers that can and / or are configured to polymerize to form any one or both of the aforementioned substances. The filter media may also comprise a polymer, oligomer, or monomer containing a fluorinated side chain. As an example, the filter media may comprise a polymer containing a -C structure. n F m R y The side chains are polymers, oligomers, or monomers. The polymers, oligomers, or monomers may be in the form of resins, or may be in another suitable form (e.g., in the form of thermoplastic polymers and / or oligomers).

[0027] In some embodiments, the water-repellent additive having minimal or no fluorine atoms comprises one or more water-repellent functional groups. The water-repellent functional groups may comprise carbon chains containing three or more carbon atoms. In some embodiments, some or all of the water-repellent functional groups are bonded to silicon atoms and / or metal atoms. Some or all of the water-repellent functional groups may also form side chains attached to the polymer backbone.

[0028] Some of the filter media described herein may exhibit improved properties compared to filter media containing other types of water-repellent additives and / or other combinations of water-repellent additives. For example, some of the filter media described herein may exhibit improved properties compared to filter media that do not contain fluorinated water-repellent additives and / or do not contain water-repellent additives having minimal or no fluorine atoms. As another example, some of the filter media described herein may exhibit improved properties compared to filter media containing fluorinated water-repellent additives other than perfluoropoly(ether), oligomeric perfluoroether, polymers and oligomers with fluorinated side chains, and monomers that can and / or can be configured to polymerize to form some or all of the aforementioned substances. In some embodiments, the filter media described herein contain a combination of fluorinated and non-fluorinated water-repellent additives and exhibit improved performance compared to filter media that do not contain fluorinated or non-fluorinated water-repellent additives. Some of the improved properties exhibited by the media described herein may include high levels of water repellency, oil repellency, and / or anti-poly(urethane) wicking properties.

[0029] Some of the filter media described herein exhibit improved properties compared to filter media containing water-repellent additives that contain a significant amount of fluorine and / or do not contain water-repellent functional groups in the form of carbon chains containing three or more carbon atoms. For example, in some embodiments, the filter media described herein contain fewer (or no) components subject to certain regulations by government agencies. Such filter media can exhibit performance comparable to or better than filter media containing such regulated water-repellent additives. Such filter media can also exhibit better performance compared to filter media containing other types of non-fluorinated water-repellent additives, such as non-fluorinated water-repellent additives that do not contain functional groups in the form of carbon chains containing three or more carbon atoms.

[0030] In some embodiments, the filter media described herein comprise an additive containing polar functional groups. The polar functional groups may be present in the same additive that also contains water-repellent functional groups, and / or may be present in different additives. Advantageously and unexpectedly, the presence of such polar functional groups can enhance the water repellency of the filter media compared to other equivalent filter media that do not contain additives containing such polar functional groups and / or do not contain such polar functional groups.

[0031] Some of the filter media described herein contain water-repellent additives with minimal or no fluorine, and also contain resins. Based on the individual properties of each of the water-repellent additives and resins, the additives and resins can work together in unexpected ways to enhance the properties of the filter media. For example, a combination of a water-repellent additive that individually exhibits considerable water repellency and a resin that individually exhibits minimal water repellency can together exhibit significantly higher water repellency than the water-repellent additive itself. Some such resins can be fluorinated resins. Some fluorinated resins may include fluorinated polymers as water-repellent additives as described above, fluorinated oligomers as water-repellent additives as described above, and / or fluorinated monomers as water-repellent additives as described above.

[0032] As described above, in some embodiments, a filter medium is provided. It should also be noted that some embodiments may involve nonwoven fiber webs used in applications other than filter media. For example, in some embodiments, one or more of the nonwoven fiber webs described herein may be part of medical protective clothing or blinds. Therefore, it should be understood that references to nonwoven fiber webs herein should be construed as describing both nonwoven fiber webs forming layers in a filter medium and nonwoven fiber webs not included in a filter medium. It should also be understood that applications other than filter media may include two or more of the nonwoven fiber webs described herein and may independently lack, or possess some or all of the characteristics described elsewhere herein regarding filter media.

[0033] Figure 1A A non-limiting embodiment of a filter medium 100 comprising a nonwoven fiber web 200 is shown. Some filter media, such as Figure 1A The filter media shown may consist of exactly one layer and / or a nonwoven fiber web. The filter media may also consist of two or more layers (e.g., three or more layers, four or more layers, more than four layers), some or all of which may be nonwoven fiber webs. The filter media may include two or more layers of the same type and / or may include two or more layers of different types. Figure 1B An example of a filter medium 102 comprising a nonwoven fiber web 202 and a layer 302 is shown.

[0034] As described above, in some embodiments, the filter media includes one or more water-repellent additives and / or one or more resins. For example, in some embodiments, the filter media may contain a first type of resin and a second type of resin. Each water-repellent additive and resin present in the filter media (if present) may be independently present in one or more of the layers present in the filter media (e.g., uniformly or non-uniformly dispersed therein), and / or independently present as a coating and / or surface layer disposed on one or more of the layers present in the filter media. The water-repellent additive dispersed in the layers of the filter media may be present on the surface of one or more fibers therein (e.g., in the form of a coating of one or more fibers). Regarding Figure 1B Each of the water-repellent additives present in the filter media and the resin (if either is present) can be independently positioned in the nonwoven fiber web 202, layer 302, on the surface of the nonwoven fiber web 202 opposite to layer 302 (e.g., in the form of a coating and / or surface layer), between the nonwoven fiber web 202 and layer 302, and / or on the surface of layer 302 opposite to the nonwoven fiber web 202. The filter media may contain two or more water-repellent additives positioned in common locations (e.g., two or more water-repellent additives positioned in a common nonwoven fiber web), and the filter media may include locations containing one water-repellent additive but not another (e.g., the filter media may include a nonwoven fiber web containing one water-repellent additive but not another water-repellent additive also present in the filter media).

[0035] Water-repellent additives suitable for inclusion in the filter media described herein can possess a variety of suitable properties. In some embodiments, the filter media contains water-repellent additives having water-repellent functional groups. This type of additive can be in the form of a resin or in different forms. The filter media may also contain one or more different types of additives (e.g., one or more non-water-repellent additives, one or more fluorine-containing additives, one or more government-regulated additives) and / or may contain one or more non-water-repellent resins (e.g., water-repellent additives other than resins, and water-repellent additives other than those that are not resins). Further details regarding some suitable water-repellent additives are provided below.

[0036] When present, the water-repellent additive can constitute various suitable amounts of the filter media. In some embodiments, the water-repellent additive constitutes greater than 0% by weight, greater than or equal to 0.001% by weight, greater than or equal to 0.002% by weight, greater than or equal to 0.005% by weight, greater than or equal to 0.0075% by weight, greater than or equal to 0.01% by weight, greater than or equal to 0.02% by weight, greater than or equal to 0.05% by weight, greater than or equal to 0.075% by weight, greater than or equal to 0.1% by weight, greater than or equal to 0.2% by weight, greater than or equal to 0.5% by weight, greater than or equal to 0.75% 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 7.5% by weight, greater than or equal to 10% by weight, greater than or equal to 15% by weight, greater than or equal to 20% by weight, greater than or equal to 25% by weight, greater than or equal to 30% by weight, or greater than or equal to 40% by weight of the filter media. In some implementations, the water-repellent additive comprises 50% or less by weight, 40% or less by weight, 30% or less by weight, 25% or less by weight, 20% or less by weight, 15% or less by weight, 10% or less by weight, 7.5% or less by weight, 5% or less by weight, 2% or less by weight, 1% or less by weight, 0.75% or less by weight, 0.5% or less by weight, 0.2% or less by weight, 0.1% or less by weight, 0.075% or less by weight, 0.05% or less by weight, 0.02% or less by weight, 0.01% or less by weight, 0.0075% or less by weight, 0.005% or less by weight, 0.002% or less by weight, or 0.001% by weight. Combinations of the above ranges are also possible (e.g., greater than 0 wt% and less than or equal to 50 wt%, greater than or equal to 0.001 wt% and less than or equal to 50 wt%, greater than or equal to 0.001 wt% and less than or equal to 25 wt%, greater than or equal to 0.001 wt% and less than or equal to 10 wt%, greater than or equal to 0.001 wt% and less than or equal to 10 wt%, greater than or equal to 0.1 wt% and less than or equal to 50 wt%, greater than or equal to 1 wt% and less than or equal to 5 wt%, or greater than or equal to 0.5 wt% and less than or equal to 50 wt%). Other ranges are also possible.

[0037] In embodiments where the filter media contains two or more water-repellent additives, each water-repellent additive may exist independently in the filter media as one or more of the above-mentioned ranges. The total amount of water-repellent additives present in the filter media may also be within one or more of the above-mentioned ranges (i.e., the filter media may contain one, two or more additives, and all additives together may account for one or more of the amount of the filter media within the above-mentioned ranges).

[0038] In some embodiments, the filter media contains at least two water-repellent additives. In such embodiments, any particular water-repellent additive may constitute a variety of suitable amounts of the total water-repellent additives. In some embodiments, the water-repellent additive constitutes a percentage of greater than or equal to 0% by weight, greater than 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 7.5% by weight, greater than or equal to 10% by weight, greater than or equal to 15% by weight, greater than or equal to 20% by weight, greater than or equal to 25% by weight, greater than or equal to 30% by weight, greater than or equal to 35% by weight, greater than or equal to 40% by weight, greater than or equal to 45% by weight, greater than or equal to 50% by weight, greater than or equal to 55% by weight, greater than or equal to 60% by weight, greater than or equal to 65% by weight, greater than or equal to 70% by weight, greater than or equal to 75% by weight, greater than or equal to 80% by weight, greater than or equal to 85% by weight, greater than or equal to 90% by weight, greater than or equal to 95% by weight, greater than or equal to 97.5% by weight, or greater than or equal to 99% by weight. In some embodiments, the water-repellent additive accounts for less than or equal to 100% by weight, less than or equal to 99% by weight, less than or equal to 97.5% by weight, 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 2.5% 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 0% by weight and less than or equal to 95% by weight, greater than or equal to 0% by weight and less than or equal to 75% by weight, greater than or equal to 0% by weight and less than or equal to 100% by weight, greater than or equal to 0% by weight and less than or equal to 95% by weight, or greater than or equal to 0% by weight and less than or equal to 75% by weight). Other ranges are also possible.

[0039] In embodiments where the filter medium contains two or more water-repellent additives, each water-repellent additive may be present independently as one or more of the aforementioned ranges. Similarly, in embodiments where the filter medium contains three or more water-repellent additives, each water-repellent additive may be present independently as one or more of the aforementioned ranges relating to all water-repellent additives and / or any subgroup of water-repellent additives (e.g., relating to one or more specific types of water-repellent additives). As an example, in some embodiments, the filter medium contains water-repellent additives comprising fluorinated polymers, oligomers, or monomers, and contains water-repellent additives having one or more water-repellent functional groups having carbon chains comprising three or more carbon atoms, and the amount of fluorinated polymers, oligomers, or monomers relative to the total weight of the two types of additives is within one or more of the aforementioned ranges.

[0040] The total amount of a specific type of water-repellent additive present in the filter media may also be within one or more of the above-mentioned ranges. As an example, the total amount of fluorinated polymers, oligomers, and / or monomeric additives may be within one or more of the above-mentioned ranges relative to the total amount of water-repellent additives. As another example, the total amount of fluorinated polymers, oligomers, and / or monomeric additives may be within one or more of the above-mentioned ranges relative to the sum of the total amount of fluorinated polymers, oligomers, and / or monomeric additives and the total amount of water-repellent additives containing one or more water-repellent functional groups having carbon chains containing three or more carbon atoms.

[0041] As described above, in some embodiments, the water-repellent additive is present in the layers of the filter medium and / or in a coating disposed on one or more layers present in the filter medium. In such embodiments, the water-repellent additive may be bonded to one or more components of the layer. As an example, in some embodiments, the water-repellent additive is bonded to at least a portion of the fibers in the fibrous layer (e.g., a nonwoven fiber web). Various suitable types of bonding can be present. For example, the bonding can be covalent bonding, ionic bonding, organometallic bonding, and / or hydrogen bonding. The water-repellent additive may also be physically trapped in the layer and / or mechanically coupled to the layer without being bonded to it.

[0042] In some embodiments, the water-repellent additive comprises one or more water-repellent functional groups having carbon chains comprising three or more carbon atoms. Each such functional group may independently be alkyl (i.e., a saturated carbon chain), alkenyl, or alkynyl. The alkenyl and alkynyl groups described herein may have any suitable degree of unsaturation. For example, an alkenyl group may contain exactly one double bond, may contain two or more double bonds, or may contain only double bonds linking carbons in the alkenyl chain. Similarly, an alkynyl group may contain exactly one triple bond, may contain two or more triple bonds, or may contain only alternating triple and single bonds along the alkynyl chain. In some embodiments, the alkynyl group comprises one or more triple bonds and one or more double bonds. When multiple double and / or triple bonds are present, they may be positioned relative to each other in any suitable manner. For example, two double bonds may be adjacent or separated by one or more bonds of another type. Similarly, two triple bonds may be separated by exactly one single bond or may be separated by two or more bonds of another type.

[0043] The alkyl, alkenyl, and alkynyl groups described herein can have a variety of suitable structures. Some suitable alkyl, alkenyl, and alkynyl groups are unbranched and / or straight-chain functional groups, while some suitable alkyl, alkenyl, and alkynyl groups are branched and / or hyperbranched. Branched alkyl, alkenyl, and alkynyl groups can be branched at a single position or at multiple positions. When branched at multiple positions, the branches can be equally spaced or unequally spaced. Similarly, an alkyl, alkenyl, or alkynyl group can contain two or more branches of equal length and / or can contain two or more branches of unequal length.

[0044] Water-repellent additives may contain unsubstituted alkyl groups, unsubstituted alkenyl groups, and / or unsubstituted alkynyl groups. Water-repellent additives may also contain substituted alkyl groups, substituted alkenyl groups, and / or substituted alkynyl groups. Substituted functional groups may be monosubstituted (i.e., they may be substituted at a single position) and / or substituted at one or more positions. A non-limiting example of suitable substitution is an aryl group.

[0045] The alkyl, alkenyl, and alkynyl groups described herein can have various suitable lengths. When present, the alkyl, alkenyl, and / or alkynyl groups can each independently contain 3 or more carbon atoms, 4 or more carbon atoms, 5 or more carbon atoms, 6 or more carbon atoms, 7 or more carbon atoms, 8 or more carbon atoms, 9 or more carbon atoms, 10 or more carbon atoms, 11 or more carbon atoms, 12 or more carbon atoms, 13 or more carbon atoms, 14 or more carbon atoms, or 15 or more carbon atoms. A number of carbon atoms, greater than or equal to 16, greater than or equal to 17, greater than or equal to 18, greater than or equal to 19, greater than or equal to 20, greater than or equal to 21, greater than or equal to 22, greater than or equal to 23, greater than or equal to 24, greater than or equal to 25, greater than or equal to 26, greater than or equal to 27, greater than or equal to 28, or greater than or equal to 29. Alkyl, alkenyl, and / or alkynyl groups may each independently contain 30 or more carbon atoms, 29 or more carbon atoms, 28 or more carbon atoms, 27 or more carbon atoms, 26 or more carbon atoms, 25 or more carbon atoms, 24 or more carbon atoms, 23 or more carbon atoms, 22 or more carbon atoms, 21 or more carbon atoms, 20 or more carbon atoms, 19 or more carbon atoms, or 1... The number of carbon atoms can be 8, 17, 16, 15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, or 4. Combinations of these ranges are also possible (e.g., 3 or more carbon atoms and 30 or less, or 8 or more carbon atoms and 30 or less). Other ranges are also possible.

[0046] In some embodiments, the water-repellent additive contains water-repellent functional groups having a number of carbon atoms that are exactly equal to any of the values ​​in the preceding paragraph (e.g., exactly equal to three carbon atoms, exactly equal to four carbon atoms, exactly equal to five carbon atoms, etc.).

[0047] In some embodiments, the hydrophobic functional group, which is alkyl, alkenyl, or alkynyl, comprises a number of carbon atoms arranged in a straight chain within one or more of the above-described ranges (e.g., an alkyl group comprising 3 or more carbon atoms and less than or equal to 30 carbon atoms can be a n-alkyl group, and similarly, an alkyl group comprising 8 carbon atoms can be a n-octyl group). The alkyl, alkenyl, or alkynyl group may also comprise a carbon chain comprising a number of carbon atoms within one or more of the above-described ranges, and further comprise one or more branches containing additional carbon atoms (e.g., an alkyl group may comprise a carbon chain comprising 3 or more carbon atoms and less than or equal to 30 carbon atoms, and the carbon chain may comprise one or more branches containing additional carbon atoms). In some embodiments, the alkyl, alkenyl, or alkynyl group comprises a number of carbon atoms not arranged in a straight chain within one or more of the above-described ranges (e.g., an alkyl group comprising 10 carbon atoms can be an ethyl-substituted octyl group).

[0048] It should also be understood that for water-repellent additives containing two or more water-repellent functional groups, each containing three or more carbon atoms, the water-repellent functional groups may be all identical, may contain at least one pair of such identical water-repellent functional groups and at least one pair of such different water-repellent functional groups, or may contain no such identical water-repellent functional groups. Furthermore, it should be understood that some filter media may contain two or more water-repellent additives that are different from each other but each contains at least one water-repellent functional group, said water-repellent functional group comprising a carbon chain containing three or more carbon atoms.

[0049] Some water-repellent additives contain a minimum or no fluorine atoms. In other words, in some embodiments, the filter medium contains a water-repellent additive that is free of fluorine atoms and / or contains a relatively small number of fluorine atoms. In some embodiments, the filter medium contains a water-repellent additive that contains a water-repellent functional group (e.g., an alkyl group containing three or more carbon atoms, an alkenyl group containing three or more carbon atoms, or an alkynyl group containing three or more carbon atoms) that is free of fluorine atoms and / or contains a relatively small number of fluorine atoms. For example, fluorine atoms may account for less than or equal to 100 atomic%, less than or equal to 90 atomic%, less than or equal to 80 atomic%, less than or equal to 70 atomic%, less than or equal to 60 atomic%, less than or equal to 50 atomic%, less than or equal to 40 atomic%, less than or equal to 30 atomic%, less than or equal to 20 atomic%, less than or equal to 10 atomic%, less than or equal to 7.5 atomic%, less than or equal to 5 atomic%, less than or equal to 4 atomic%, less than or equal to 3 atomic%, or less than or equal to 2 atomic%. Fluorine atoms can comprise 1.5 atomic percent, 2 atomic percent, 3 atomic percent, 4 atomic percent, 5 atomic percent, 7.5 atomic percent, 10 atomic percent, 20 atomic percent, 30 atomic percent, 40 atomic percent, 50 atomic percent, 60 atomic percent, 70 atomic percent, 80 atomic percent, or 90 atomic percent of the atoms bonded to carbon atoms in the water-repellent functional group. Combinations of these ranges are also possible (e.g., greater than or equal to 1.5 atomic percent and less than or equal to 100 atomic percent). Other ranges are also possible. In some embodiments, fluorine atoms similarly comprise 0% of the atoms bonded to carbon atoms in the water-repellent functional group.

[0050] It should also be understood that for water-repellent additives containing two or more water-repellent functional groups, each water-repellent functional group may independently contain an amount of fluorine within one or more of the above-mentioned ranges. Furthermore, it should be understood that some filter media may contain two or more water-repellent additives that are different from each other but each contains at least one water-repellent functional group, said water-repellent functional group containing an amount of fluorine within one or more of the above-mentioned ranges.

[0051] In some embodiments, the water-repellent additive comprises a water-repellent functional group (e.g., an alkyl group containing three or more carbon atoms, an alkenyl group containing three or more carbon atoms, or an alkynyl group containing three or more carbon atoms), wherein the water-repellent functional group comprises less than or equal to 7 fluorine atoms, less than or equal to 6 fluorine atoms, less than or equal to 5 fluorine atoms, less than or equal to 4 fluorine atoms, less than or equal to 3 fluorine atoms, less than or equal to 2 fluorine atoms, or less than or equal to 1 fluorine atom. In some embodiments, the water-repellent additive comprises a water-repellent functional group comprising more than or equal to 0 fluorine atoms, more than or equal to 1 fluorine atom, more than or equal to 2 fluorine atoms, more than or equal to 3 fluorine atoms, more than or equal to 4 fluorine atoms, more than or equal to 5 fluorine atoms, or more than or equal to 6 fluorine atoms. Combinations of the above ranges are also possible (e.g., more than or equal to 0 fluorine atoms and less than or equal to 7 fluorine atoms). Other ranges are also possible. Furthermore, in some embodiments, the water-repellent functional group also comprises 0 fluorine atoms.

[0052] It should also be understood that for water-repellent additives containing two or more water-repellent functional groups, each water-repellent functional group may independently contain an amount of fluorine within one or more of the above-mentioned ranges. Furthermore, it should be understood that some filter media may contain two or more water-repellent additives that are different from each other but each contains at least one water-repellent functional group, said water-repellent functional group containing an amount of fluorine within one or more of the above-mentioned ranges.

[0053] In some embodiments, the water-repellent additive containing a water-repellent functional group (e.g., an alkyl group containing three or more carbon atoms, an alkenyl group containing three or more carbon atoms, or an alkynyl group containing three or more carbon atoms) also contains silicon atoms and / or metal atoms. The water-repellent functional group may be bonded to silicon atoms and / or metal atoms. For example, in some embodiments, the water-repellent additive has one or both of the structures shown below:

[0054] (Structure 1) and (Structure 2).

[0055] In structures 1 and 2, R1 is a water-repellent functional group (e.g., it is an alkyl group containing three or more carbon atoms, an alkenyl group containing three or more carbon atoms, or an alkynyl group containing three or more carbon atoms). Furthermore, R2, R3, and R4 are any suitable functional groups. As described above, in some embodiments, one, both, or all of R2, R3, and R4 are also water-repellent functional groups (e.g., having the same structure as R1 and / or the same structure as each other, having a different structure from R1 and / or a different structure from each other). In other words, the water-repellent additive may contain two water-repellent functional groups, both bonded to the same silicon or metal atom. One, both, or all of R2, R3, and R4 may also be functional groups other than water-repellent functional groups (e.g., having the same structure as each other, having a different structure from each other). Further details regarding suitable structures of R2, R3, and R4 are provided elsewhere herein.

[0056] In embodiments where the water-repellent additive has a structure as shown in Structure 2, M can be a variety of suitable metals. In some embodiments, M is a post-transition metal (e.g., aluminum). M can also be a transition metal (e.g., titanium, zirconium).

[0057] Other examples of suitable water-repellent additives are shown below:

[0058] (Structure 3) (Structure 4) (Structure 5) and (Structure 6).

[0059] Structures 3 through 6 describe silanols, siloxides, silyl ethers, and silanes, respectively. In structures 3 through 6: R1 is a hydrophobic functional group (e.g., an alkyl group containing three or more carbon atoms, an alkenyl group containing three or more carbon atoms, or an alkynyl group containing three or more carbon atoms); and R3 and R4 are any suitable functional groups. In structure 4, M is a metal (e.g., a late transition metal such as aluminum, a transition metal such as titanium, or zirconium). In structures 5 and 6, R5 is any suitable functional group. In structure 6, R6 and R7 are any suitable functional groups. In some embodiments, one, two, or all of R3, R4, R5, R6, and R7 (when present) are also hydrophobic functional groups (e.g., having the same structure as R1 and / or the same structure as each other, having a different structure from R1 and / or a different structure from each other). One, two, or all of R3, R4, R5, R6, and R7 may also be functional groups other than water-repellent functional groups (e.g., having the same structure as each other, having different structures from each other).

[0060] According to some implementation schemes, the water-repellent additive is not based on silicone. According to some implementation schemes, the water-repellent additive is silicone-free.

[0061] In some embodiments, the water-repellent additive containing a water-repellent functional group (e.g., an alkyl group containing three or more carbon atoms, an alkenyl group containing three or more carbon atoms, or an alkynyl group containing three or more carbon atoms) is a polymer. In such embodiments, the water-repellent functional group can form the side chain of a repeating unit of the polymer. As an example, the water-repellent additive can have the following structure:

[0062] (Structure 7).

[0063] In structure 7: the main chain is one or more atoms forming the main chain of the polymer; R1 is a hydrophobic functional group (e.g., it is an alkyl group containing three or more carbon atoms, an alkenyl group containing three or more carbon atoms, or an alkynyl group containing three or more carbon atoms); R2 and R3 are any suitable end groups; and n is any suitable value. None, either, or both of R2 and R3 can be hydrophobic functional groups. In some embodiments, one or more additional side chains may also be bonded to the main chain (not shown). Some, none, or all of such side chains may also be hydrophobic. Furthermore, compared to [other structures], some, none, or all of such additional side chains may be bonded to the same atom as the hydrophobic functional group.

[0064] Various suitable backbones can be used. In some implementations, the backbone is formed of carbon atoms. The backbone may also contain one or more heteroatoms (e.g., silicon atoms, oxygen atoms, nitrogen atoms).

[0065] Non-limiting examples of suitable repeating units (i.e., containing both the main chain and the water-repellent functional group) include polymerized acrylic repeating units (e.g., the polymer may be poly(acrylate)), polymerized urethane repeating units (e.g., the polymer may be poly(urethane)), polymerized epoxy repeating units (e.g., the polymer may be poly(ether)), polymerized urea repeating units (e.g., the polymer may be poly(urea)), polymerized ester repeating units (e.g., the polymer may be poly(ester)), polymerized siloxane repeating units (e.g., the polymer may be poly(siloxane)), polymerized silazane repeating units (e.g., the polymer may be poly(silazane)), and polymerized carbodiimide repeating units (e.g., the polymer may be poly(carbodiimide)). In some embodiments, the functional groups of the water-repellent additive are silicone-free. Therefore, in some embodiments, the repeating units are silicone-free.

[0066] Further examples of suitable polymers include hydrolysis products of substances comprising metal atoms, hydrolyzable functional groups, and one or more hydrophobic functional groups (e.g., alkyl groups comprising three or more carbon atoms, alkenyl groups comprising three or more carbon atoms, and / or alkynyl groups comprising three or more carbon atoms). These substances may contain post-transition metals (e.g., aluminum) and / or transition metals (e.g., titanium, zirconium). The hydrolysis products may be in the form of organometallic compounds (e.g., organoaluminum compounds, organotitanium compounds, and / or organozirconium compounds).

[0067] In some embodiments, such as the one shown in Structure 7, the water-repellent additive containing water-repellent functional groups is a homopolymer. The filter medium may also contain a water-repellent additive that is a polymer other than a homopolymer. For example, in some embodiments, the water-repellent additive comprises repeating units containing side chains having water-repellent functional groups (e.g., alkyl groups containing three or more carbon atoms, alkenyl groups containing three or more carbon atoms, alkynyl groups containing three or more carbon atoms), and the water-repellent additive further comprises one or more different types of repeating units. Different types of repeating units may include repeating units containing water-repellent functional groups (e.g., repeating units of a different type than the first repeating unit containing water-repellent functional groups, repeating units of the same type as the first repeating unit containing water-repellent functional groups but attached to a different type of main chain) and / or may include repeating units without water-repellent functional groups.

[0068] Water-repellent additives can be copolymers, such as dimers, trimers, tetramers, or any other suitable type of polymer. Furthermore, the arrangement of repeating units in the copolymer can often be selected as needed. To provide non-limiting examples, suitable water-repellent additives may include random copolymers, alternating copolymers, periodic copolymers, statistical copolymers, block copolymers, regular block copolymers, stereoblock copolymers, graded copolymers, and / or graft copolymers. Structures 8 and 9 below illustrate two non-limiting examples of suitable random copolymers and block copolymers, respectively:

[0069] (Structure 8) and

[0070] (Structure 9).

[0071] In structures 8 and 9: the main chain is one or more atoms of a portion of the main chain associated with a repeating unit containing a water-repellent functional group forming the polymer; repeating unit 2 is a repeating unit copolymerized with a repeating unit containing a water-repellent functional group; R1 is a water-repellent functional group (e.g., it is an alkyl group containing three or more carbon atoms, an alkenyl group containing three or more carbon atoms, or an alkynyl group containing three or more carbon atoms); and R2 and R3 are any suitable end groups. In structure 8: n is any suitable value; x and y can be selected as needed and can vary over the length of the polymer. In structure 9: n1 and n2 can be selected as needed. None of R2 and R3, either or both, can be water-repellent functional groups. Similarly, the repeating unit including the main chain may contain one or more additional water-repellent functional groups, and / or repeating unit 2 may contain one or more water-repellent functional groups.

[0072] Various suitable main chains can be used for both the main chain and repeating unit 2. In some embodiments, the main chain is formed of carbon atoms. The main chain may also contain one or more heteroatoms (e.g., silicon atoms, oxygen atoms, nitrogen atoms).

[0073] Non-limiting examples of suitable repeating units comprising both repeating unit R1 and repeating unit 2 include polymerized acrylic repeating units (e.g., the polymer may be poly(acrylate)), polymerized urethane repeating units (e.g., the polymer may be poly(urethane)), polymerized epoxy repeating units (e.g., the polymer may be poly(ether)), polymerized siloxane repeating units (e.g., the polymer may be poly(siloxane)), and polymerized silazane repeating units (e.g., the polymer may be poly(silazane)). In some embodiments, the copolymer of the water-repellent additive is silicone-free. Therefore, in some embodiments, the repeating units are silicone-free.

[0074] The water-repellent additive may also be an oligomer and contain water-repellent functional groups (e.g., alkyl functional groups containing three or more carbon atoms, alkenyl functional groups containing three or more carbon atoms, or alkynyl functional groups containing three or more carbon atoms). For example, in some embodiments, the water-repellent additive is an oligomer having the structure shown in any of structures 7 to 9, wherein n, x, or the sum of n1 and n2 is sufficiently small for the molecule to be an oligomer.

[0075] In some embodiments, the water-repellent additive has a three-dimensional structure. For example, in some embodiments, the water-repellent additive is a covalent network. The covalent network can be crystalline, amorphous, or semi-crystalline. A water-repellent additive with a three-dimensional structure may contain one or more water-repellent functional groups (e.g., alkyl functional groups containing three or more carbon atoms, alkenyl functional groups containing three or more carbon atoms, or alkynyl functional groups containing three or more carbon atoms). Such water-repellent additives may also contain other types of functional groups. In some embodiments, the water-repellent additive with a three-dimensional structure also contains silicon atoms, metal atoms (e.g., titanium, zirconium, and / or aluminum atoms), oxygen atoms, and / or nitrogen atoms. In some such embodiments, the metal and / or silicon atoms may be bonded to both the oxygen atom and the water-repellent functional group. A non-limiting example of a suitable covalent network is a silsesquioxane.

[0076] In some embodiments, water-repellent additives containing water-repellent functional groups (e.g., alkyl functional groups containing three or more carbon atoms, alkenyl functional groups containing three or more carbon atoms, alkynyl functional groups containing three or more carbon atoms) also contain one or more polar functional groups. The polar functional groups can be non-hydrolyzable functional groups and / or functional groups that are stable during the preparation and / or use of the filter media. Non-limiting examples of suitable polar functional groups include amino, acetoxy, and acetamido. Furthermore, when a water-repellent additive contains two or more polar functional groups, it may contain only one type of polar functional group, only different types of polar functional groups, or at least two of the same type of polar functional groups and at least two different types of polar functional groups.

[0077] When present, polar functional groups can be positioned at various suitable locations in the water-repellent additives described herein. For example, in water-repellent additives containing silicon or metal atoms bonded to the water-repellent functional groups, the polar functional groups can also be bonded to the silicon or metal atoms. Referring to structures 1 and 2, all, some, or none of R2, R3, and R4 can be polar functional groups. Similarly, referring to structures 3 to 6, all, some, or none of R3, R4, R5, R6, and R7 can also be polar functional groups.

[0078] In some embodiments, the water-repellent additive for oligomers or polymers comprises polar functional groups. As an example, the water-repellent additive comprising oligomers or polymers may also comprise polar functional groups, said oligomers or polymers comprising repeating units containing water-repellent functional groups (e.g., alkyl groups containing three or more carbon atoms, alkenyl groups containing three or more carbon atoms, alkynyl groups containing three or more carbon atoms). Referring to structures 7 to 9, the polar functional group may be attached to the main chain, and / or either R2 or R3, both or none of them may be polar functional groups. When a polar functional group is attached to the main chain, it may or may not be directly attached to the same atom to which the water-repellent functional group is attached. Referring to structures 8 and 9, the polar functional group may be attached to repeating unit 2. In other words, polymeric or oligomeric water-repellent additives may: contain repeating units with a single atom bonded to both polar and water-repellent functional groups; contain repeating units with polar functional groups bonded to different main chain atoms compared to the water-repellent functional groups; contain one repeating unit with a water-repellent functional group and another different repeating unit with a polar functional group; and / or contain end groups with polar functional groups.

[0079] In some implementations, the water-repellent additive for covalent networks contains one or more polar functional groups (e.g., in addition to water-repellent functional groups).

[0080] It should also be noted that some water-repellent additives (e.g., those having the structures shown in one or more of structures 1 to 9, those containing silicon atoms and / or metal atoms, those being polymers, those being oligomers, those being covalent networks) may contain one or more functional groups that are neither water-repellent nor polar functional groups. Such functional groups can be positioned at any suitable location (e.g., any location in structures 1 to 9 that is neither a water-repellent nor a polar functional group). Non-limiting examples of functional groups that are neither water-repellent nor polar functional groups as described herein include hydrogen, methyl, and ethyl.

[0081] In some embodiments, the filter medium comprises an additive containing a polar functional group (e.g., a polar functional group suitable for inclusion in a water-repellent additive as described elsewhere herein). The additive containing a polar functional group may also be a water-repellent additive (e.g., as described elsewhere herein) and / or contain a water-repellent functional group (e.g., an alkyl group containing three or more carbon atoms, an alkenyl group containing three or more carbon atoms, or an alkynyl group containing three or more carbon atoms). The additive containing a polar functional group may also be free of water-repellent functional groups. The additive containing a polar functional group may have a structure similar to one or more of the structures shown in structures 1 to 9, differing only in that R1 is not a water-repellent functional group, and one or more of the functional groups present (e.g., some or all of R1 to R9) are polar functional groups.

[0082] When the filter media contains water-repellent additives and / or combinations of additives containing one or more water-repellent functional groups (e.g., alkyl groups containing three or more carbon atoms, alkenyl groups containing three or more carbon atoms, alkynyl groups containing three or more carbon atoms) and one or more polar functional groups (e.g., combinations of water-repellent additives containing at least one water-repellent additive and at least one additive other than a water-repellent additive), the relative amounts of water-repellent and polar functional groups are generally selected as needed. In some embodiments, the ratio of the number of water-repellent functional groups to the number of polar functional groups is greater than or equal to 0.1, greater than or equal to 0.15, greater than or equal to 0.2, greater than or equal to 0.25, greater than or equal to 0.33, greater than or equal to 0.5, greater than or equal to 0.75, greater than or equal to 1, greater than or equal to 1.5, greater than or equal to 2, greater than or equal to 2.5, greater than or equal to 3, greater than or equal to 4, greater than or equal to 5, or greater than or equal to 7.5. In some implementations, the ratio of the number of water-repellent functional groups to the number of polar functional groups is less than or equal to 10, less than or equal to 7.5, less than or equal to 5, less than or equal to 4, less than or equal to 3, less than or equal to 2.5, less than or equal to 2, less than or equal to 1.5, less than or equal to 1, less than or equal to 0.75, less than or equal to 0.5, less than or equal to 0.33, less than or equal to 0.25, less than or equal to 0.2, or less than or equal to 0.15. Combinations of the above ranges are also possible (e.g., greater than or equal to 0.1 and less than or equal to 10, greater than or equal to 0.2 and less than or equal to 5, or greater than or equal to 0.33 and less than or equal to 3). Other ranges are also possible.

[0083] In some embodiments, the single water-repellent additive present in the filter medium (which may be free of other water-repellent additives or may contain other water-repellent additives) has a ratio of the number of water-repellent functional groups to the number of polar functional groups within one or more of the above-mentioned ranges. In some embodiments, the ratio of the number of water-repellent functional groups to the number of polar functional groups in the filter medium as a whole is within one or more of the above-mentioned ranges.

[0084] When a filter medium contains a polymeric water-repellent additive that simultaneously contains one or more repeating units comprising water-repellent functional groups (e.g., alkyl groups comprising three or more carbon atoms, alkenyl groups comprising three or more carbon atoms, alkynyl groups comprising three or more carbon atoms) and one or more repeating units comprising polar functional groups, the relative amounts of repeating units comprising water-repellent functional groups and repeating units comprising polar functional groups are typically selected as needed. In some embodiments, the ratio of the number of repeating units comprising water-repellent functional groups to the number of repeating units comprising polar functional groups is greater than or equal to 0.1, greater than or equal to 0.15, greater than or equal to 0.2, greater than or equal to 0.25, greater than or equal to 0.33, greater than or equal to 0.5, greater than or equal to 0.75, greater than or equal to 1, greater than or equal to 1.5, greater than or equal to 2, greater than or equal to 2.5, greater than or equal to 3, greater than or equal to 4, greater than or equal to 5, or greater than or equal to 7.5. In some implementations, the ratio of the number of repeating units containing water-repellent functional groups to the number of repeating units containing polar functional groups is less than or equal to 10, less than or equal to 7.5, less than or equal to 5, less than or equal to 4, less than or equal to 3, less than or equal to 2.5, less than or equal to 2, less than or equal to 1.5, less than or equal to 1, less than or equal to 0.75, less than or equal to 0.5, less than or equal to 0.33, less than or equal to 0.25, less than or equal to 0.2, or less than or equal to 0.15. Combinations of the above ranges are also possible (e.g., greater than or equal to 0.1 and less than or equal to 10, greater than or equal to 0.2 and less than or equal to 5, or greater than or equal to 0.33 and less than or equal to 3). Other ranges are also possible. When the repeating unit contains both water-repellent and polar functional groups, the number of the two types of functional groups that contribute to the above ratio is considered to be...

[0085] Some filter media described herein contain one or more water-repellent additives in the form of fluorinated polymers, fluorinated oligomers, and / or fluorinated monomers. Such water-repellent additives may be in the form of resins or resin components. Such water-repellent additives may also be provided in forms different from resins or resin components. Fluorinated water-repellent additives may contain one or more water-repellent functional groups, such as those described above (e.g., alkyl groups containing three or more carbon atoms, alkenyl groups containing three or more carbon atoms, alkynyl groups containing three or more carbon atoms), or may not contain such functional groups. Fluorinated water-repellent additives (e.g., fluorinated polymers, fluorinated oligomers, fluorinated monomers) may also be provided together with water-repellent additives containing one or more water-repellent functional groups, such as those described above (e.g., alkyl groups containing three or more carbon atoms, alkenyl groups containing three or more carbon atoms, alkynyl groups containing three or more carbon atoms), or may also be present in filter media without such water-repellent additives. In some embodiments, the filter media contains fluorinated polymers, fluorinated oligomers, or fluorinated monomers and does not contain any additional water-repellent additives.

[0086] Water-repellent additives for fluorinated polymers can be homopolymers or copolymers (e.g., dimers, trimers, tetramers, or any other suitable type of copolymer). Similarly, water-repellent additives for fluorinated oligomers can be homooligomers or cooligomers (e.g., binary oligomers, ternary oligomers, quaternary oligomers, or any other suitable type of cooligomer). Fluorinated copolymers and fluorinated cooligomers may contain unfluorinated repeating units or may consist only of fluorinated repeating units. The arrangement of repeating units in fluorinated copolymers and fluorinated cooligomers is generally selected as needed. To provide non-limiting examples, suitable fluorinated copolymers and cooligomers may include random copolymers and cooligomers, alternating copolymers and cooligomers, periodic copolymers and cooligomers, statistical copolymers and cooligomers, block copolymers and cooligomers, regular block copolymers and cooligomers, stereoblock copolymers and cooligomers, graded copolymers and cooligomers, and / or graft copolymers and cooligomers.

[0087] Fluorinated polymers and fluorinated oligomers suitable for use with the filter media described herein may comprise a fluorinated backbone and / or one or more fluorinated side chains (e.g., a plurality of fluorinated side chains). Non-limiting examples of fluorinated water-repellent additives include fluorinated poly(ethers) (e.g., perfluorinated poly(ethers)), oligofluoroethylene ethers, fluorinated poly(urethane), oligofluoroethylene urethane, and those comprising a compound having the formula -C n F m R y Polymers and oligomers with side chains containing structural motifs. Some filter media contain two or more of the above-mentioned types of water-repellent additives (e.g., fluorinated poly(ether) and those containing the formula -C).n F m R y (Polymers with side chains of structural motifs). The filter media may also contain two or more different water-repellent additives (e.g., two or more fluorinated poly(ethers)) that both fall into one or more of the above categories.

[0088] As described above, in some embodiments, the filter medium comprises a water-repellent additive that is a perfluoropoly(ether), a water-repellent additive that is an oligomeric perfluoroether, and / or a monomeric perfluoroether. In some embodiments, the filter medium comprises not only a water-repellent additive containing the water-repellent functional groups described above (e.g., alkyl groups containing three or more carbon atoms, alkenyl groups containing three or more carbon atoms, alkynyl groups containing three or more carbon atoms), but also perfluoropoly(ether), oligomeric perfluoroether, and / or a monomeric perfluoroether. The filter medium may also not contain a water-repellent additive containing the water-repellent functional groups described above (e.g., alkyl groups containing three or more carbon atoms, alkenyl groups containing three or more carbon atoms, alkynyl groups containing three or more carbon atoms), but may contain perfluoropoly(ether), oligomeric perfluoroether, and / or a monomeric perfluoroether.

[0089] Perfluoropoly(ether) and oligomeric perfluoroether can contain perfluoroether chains. Monomeric perfluoroethers can contain perfluoroether functional groups, perfluoroether chains, and / or functional groups that can and / or be configured to polymerize into perfluoroether chains. Some suitable perfluoroether chains have the structure -(C n F m O) x - where n and m are integers chosen appropriately to form an effective structure. Chemical formula (C n F m O) x In the given range, x can be less than or equal to 10, less than or equal to 8, less than or equal to 6, less than or equal to 4, or less than or equal to 2. x can be greater than or equal to 1, greater than or equal to 2, greater than or equal to 4, greater than or equal to 6, or greater than or equal to 8. Combinations of the above ranges are also possible (e.g., less than or equal to 10 and greater than or equal to 1). Other ranges are also possible.

[0090] In some implementations, the chemical formula (C n F m O) x The x in - is exactly equal to any value in the preceding paragraph (e.g., exactly equal to 10, exactly equal to 8, exactly equal to 6, etc.).

[0091] Contains chemical formula (C n F m O) xNon-limiting examples of polymers with perfluoroether chains include poly(perfluoromethylene oxide), poly(perfluoroethylene oxide), poly(perfluoropropylene oxide), and poly(perfluorobutane oxide). Further non-limiting examples of suitable repeating units for perfluoroether chains include -(C n F 2n O) x -, where n is an integer (e.g., -(C3F6O)). x -、-(C4F8O) x -、-(C5F 10 O) x -); -(CF(CF3)CF2O) x -;-(CF2CF2O) x -;-(CF(CF3)CF2O) x -CF(CF3)CONH-;-(CF2(CF2) z’ CF2O) x - where z' is an integer; -(CFLO) x -, where L = -F or -CF3; and -(CH2CF2CF2O) x - In some embodiments, the water-repellent additive for perfluoropoly(ether), the water-repellent additive for oligomeric perfluoroether, and / or the water-repellent additive for monomeric perfluoroether comprises having the formula (C n F 2n+1 O) x - is an end base, where n is an integer (e.g., -(CF3O)). x -、-(C2F5O) x - and -(C3F7O) x -). Water-repellent additives that are perfluoropoly(ether), water-repellent additives that are oligomeric perfluoroethers, and / or water-repellent additives that are monomeric perfluoroethers may also contain -SO3. 2- As end groups. Some end groups can be non-polymerizable.

[0092] In some embodiments, the fluorinated polymer is fluorinated poly(urethane), the fluorinated oligomer is fluorinated oligourethane, the fluorinated monomer contains urethane functional groups, and / or the fluorinated monomer contains one or more functional groups configured to react to form fluorinated poly(urethane) and / or fluorinated oligourethane. In some embodiments, the filter media not only contains water-repellent additives containing water-repellent functional groups as described above (e.g., alkyl groups containing three or more carbon atoms, alkenyl groups containing three or more carbon atoms, alkynyl groups containing three or more carbon atoms), but also contains fluorinated poly(urethane), fluorinated oligourethane, fluorinated monomers containing urethane functional groups, and / or fluorinated monomers containing one or more functional groups configured to react to form fluorinated poly(urethane) and / or fluorinated oligourethane. The filter media may also be free of water-repellent additives containing water-repellent functional groups as described above (e.g., alkyl groups containing three or more carbon atoms, alkenyl groups containing three or more carbon atoms, alkynyl groups containing three or more carbon atoms), but may contain fluorinated poly(urethane), fluorinated oligourethane, fluorinated monomers containing urethane functional groups, and / or fluorinated monomers containing one or more functional groups configured to react to form fluorinated poly(urethane) and / or fluorinated oligourethane.

[0093] A non-limiting example of fluorinated poly(urethane) is a polymer having the following structure 10:

[0094] (Structure 10)

[0095] In structure 10, R F =(CF2CF2O) x (CF2O) y Therefore, structure 10 is both poly(ether) and poly(urethane). Other polymers that are both poly(ether) and poly(urethane) can also be used. Similarly, oligomers containing both ether repeating units and urethane repeating units are also possible.

[0096] In some embodiments, the fluorinated polymer, fluorinated oligomer, and / or fluorinated monomer comprises a structure having a -C n F m R y The chain. In some embodiments, the filter media not only contains water-repellent additives containing water-repellent functional groups as described above (e.g., alkyl groups containing three or more carbon atoms, alkenyl groups containing three or more carbon atoms, alkynyl groups containing three or more carbon atoms), but also contains additives containing the structure -C n F m R yFluorinated polymers, fluorinated oligomers, and / or fluorinated monomers with a chain. The filter media may also be free of water-repellent additives containing the water-repellent functional groups described above (e.g., alkyl groups containing three or more carbon atoms, alkenyl groups containing three or more carbon atoms, alkynyl groups containing three or more carbon atoms), but may contain additives with a -C structure. n F m R y Fluorinated polymers, fluorinated oligomers and / or fluorinated monomers with fluorinated chains.

[0097] When present, the chain can be a side chain and / or part of a side chain. In other words, fluorinated polymers and / or fluorinated oligomers can contain and / or have the structure -C n F m R y The side chain. In some embodiments, the fluorinated polymer and / or fluorinated oligomer includes a side chain that comprises a component having the formula -C n F m R y The side chain is connected to the linking group of the main chain. The side chain can be in the form of formula -C n F m R y Termination. Fluorinated polymers, fluorinated oligomers, and / or fluorinated monomers may be fluorinated acrylate polymers, fluorinated acrylate oligomers, and / or fluorinated acrylate monomers.

[0098] In structure-C n F m R y In this context, n, m, and y can be chosen as needed. n can be an integer greater than 1. m can be an integer greater than 1. R can be zero, an atom, or a group of atoms (e.g., hydrogen, oxygen, sulfur, nitrogen, carbon, or an end group as described herein). y can be an integer greater than or equal to 0. In some embodiments, n is an integer less than or equal to 8, and m is an integer greater than 1 (e.g., in structure -C8F). 15 H2, -C8F 16 H1 and -C8F 17 (m). n can also be an integer less than or equal to 6, and m can be an integer greater than 1. For example, in a particular implementation, the chain inclusion formula is C6F. 12 H1. In another instance, chain inclusion - C6F 13 In some implementations, n is an integer less than or equal to 4, and m is an integer greater than 1 (e.g., -C4F7H2, -C4F8H1, -C4F9). In some implementations, the chain may contain the formula -C n F 2n+1 (For example, -(CF2)) n CF3, as in -(CF2)n CF3, where n is greater than or equal to 2 and less than or equal to 3). As another example, in some implementations, n is an integer greater than or equal to 6, and m is an integer greater than 1.

[0099] As having the formula -C n F m R y Another possible structure, in some implementations, is that n is greater than or equal to 3 and less than or equal to 5 (e.g., greater than or equal to 3 and less than or equal to 4), m is greater than or equal to 1, R is an atom or group of atoms, and y is greater than or equal to 0. m can also be equal to 2n+1 (e.g., in the case of y=0).

[0100] Water-repellent additives, which are polymers (e.g., fluorinated polymers, polymers containing water-repellent functional groups as described elsewhere herein), oligomers (e.g., fluorinated oligomers, oligomers containing water-repellent functional groups as described elsewhere herein), or monomers, can have a variety of suitable molecular weights. In some embodiments, the weight-average molecular weight of the water-repellent additive, which is a polymer, oligomer, or monomer, is greater than or equal to 169 g / mol, greater than or equal to 200 g / mol, greater than or equal to 300 g / mol, greater than or equal to 400 g / mol, greater than or equal to 500 g / mol, greater than or equal to 600 g / mol, greater than or equal to 750 g / mol, greater than or equal to 1 kg / mol, greater than or equal to 2 kg / mol, greater than or equal to 5 kg / mol, greater than or equal to 7.5 kg / mol, greater than or equal to 10 kg / mol, greater than or equal to 15 kg / mol, greater than or equal to 20 kg / mol, greater than or equal to 30 kg / mol, greater than or equal to 50 kg / mol, greater than or equal to 60 kg / mol, greater than or equal to 75 kg / mol, greater than or equal to 100 kg / mol, greater than or equal to 125 kg / mol, greater than or equal to 150 kg / mol, or greater than or equal to 175 kg / mol. In some embodiments, the weight-average molecular weight of the water-repellent additive, which is a polymer, oligomer, or monomer, is less than or equal to 200 kg / mol, less than or equal to 175 kg / mol, less than or equal to 150 kg / mol, less than or equal to 125 kg / mol, less than or equal to 100 kg / mol, less than or equal to 75 kg / mol, less than or equal to 60 kg / mol, less than or equal to 50 kg / mol, less than or equal to 30 kg / mol, less than or equal to 20 kg / mol, less than or equal to 15 kg / mol, less than or equal to 10 kg / mol, less than or equal to 7.5 kg / mol, less than or equal to 5 kg / mol, less than or equal to 2 kg / mol, less than or equal to 1 kg / mol, less than or equal to 750 g / mol, less than or equal to 600 g / mol, less than or equal to 500 g / mol, less than or equal to 400 g / mol, less than or equal to 300 g / mol, or less than or equal to 200 g / mol. Combinations of the above ranges are also possible (e.g., greater than or equal to 169 g / mol and less than or equal to 200 kg / mol, greater than or equal to 200 g / mol and less than or equal to 200 kg / mol, greater than or equal to 500 g / mol and less than or equal to 100 kg / mol, or greater than or equal to 1 kg / mol and less than or equal to 50 kg / mol). Other ranges are also possible.

[0101] The weight-average molecular weight of polymers, oligomers or monomers can be measured using gel permeation chromatography according to ASTM D5296 (2019).

[0102] When the filter medium contains two or more polymeric water-repellent additives, two or more oligomeric water-repellent additives, and / or both polymeric and oligomeric water-repellent additives, each polymeric and oligomeric water-repellent additive may independently have a molecular weight within one or more of the above-described ranges. In some embodiments, the water-repellent additive (e.g., a water-repellent additive containing water-repellent functional groups, a water-repellent additive having a structure described elsewhere herein and / or a structure as shown in structures 1 to 9) is a reaction product of one or more precursors and / or monomers. Such reaction products and / or monomers may also have a molecular weight within one or more of the above-described ranges. Of course, the water-repellent additives described herein may also be reaction products not obtained from precursors and / or may be provided directly to the filter medium in their final form. When this occurs, the reaction forming the water-repellent additive may take place before and / or during the manufacture of the filter medium. As an example, in some embodiments, the reaction may take place during the step of forming a layer in which the water-repellent additive is positioned (e.g., a wet web forming step). As another example, in some implementations, the reaction can occur during steps (e.g., drying, curing, post-curing) after the precursor is introduced into a layer present in the filter medium.

[0103] In some embodiments, the reaction forming the water-repellent additive includes reacting two or more precursors that each contribute one or more functional groups to the reaction product with each other (e.g., in addition and / or polymerization reactions), reacting one or more precursors that contribute functional groups to the reaction product with one or more precursors that do not contribute functional groups to the reaction product (e.g., in a reaction catalyzed by one or more precursors that do not contribute functional groups to the reaction product), and / or reacting one or more precursors with one or more components in which the water-repellent additive is present and / or in which the water-repellent additive is disposed (e.g., grafting reaction). Non-limiting examples of suitable types of reactions that can occur include hydrolysis reactions, condensation reactions, and curing reactions.

[0104] When the water-repellent additive is a reaction product of one or more precursors, the precursor contributing functional groups to the reaction product may contain one or more functional groups configured to and / or capable of carrying out the relevant reaction. As an example, a precursor contributing functional groups to the reaction product and configured to carry out a hydrolysis reaction may contain one or more hydrolyzable functional groups. Non-limiting examples of suitable hydrolyzable functional groups include oxygen-containing functional groups (e.g., alcohol functional groups, methoxy functional groups, ethoxy functional groups, propoxy functional groups, butoxy functional groups, longer-chain oxygen-containing functional groups) and halogenated functional groups (e.g., fluorine, chlorine, bromine). The functional groups configured to and / or capable of carrying out the reaction may be bonded to silicon or metal atoms prior to carrying out the relevant reaction. The silicon or metal atom may be a silicon or metal atom bonded to a water-repellent functional group and / or a silicon or metal atom bonded to a polar functional group. During and / or after the reaction, the functional groups configured to carry out the reaction may be partially or completely removed from the precursor, water-repellent additive, and / or filter media. Non-limiting examples of suitable precursors containing silicon and / or metal atoms include silanes (e.g., n-octyltrimethoxysilane, n-hexadecyltrimethoxysilane), titanates / salts, zirconates / salts, and aluminates / salts.

[0105] Without being bound by any particular theory, it is believed that the number of hydrolyzable functional groups present in the precursor may affect the structure of the reaction product formed by its reaction. A precursor containing one hydrolyzable functional group can react with another reactive substance (e.g., another precursor containing one or more hydrolyzable functional groups, part of a filter medium layer) upon hydrolysis of that hydrolyzable functional group and / or be configured to react with another reactive substance (e.g., another precursor containing one or more hydrolyzable functional groups, part of a filter medium layer), and thus can react to form a small molecule. A precursor containing two hydrolyzable functional groups can react with two other reactive substances (e.g., another precursor containing one or more hydrolyzable functional groups, part of a filter medium layer) upon hydrolysis of that functional group and / or be configured to react with two other reactive substances (e.g., another precursor containing one or more hydrolyzable functional groups, part of a filter medium layer), and thus can react to form a polymer, oligomer, or other linear molecule. Precursors containing three or more hydrolyzable functional groups can react upon hydrolysis of the functional groups to form branched reaction products and / or covalent networks. When using combinations of precursors (containing precursors with different amounts of hydrolyzable functional groups), combinations of the above-described reaction products can be formed, and / or reaction products having the characteristics of two or more of the above-described reaction products can be formed.

[0106] At least a portion of one or more precursors of the water-repellent additive that contribute functional groups to the reaction product may also contain water-repellent functional groups (e.g., alkyl groups containing three or more carbon atoms, alkenyl groups containing three or more carbon atoms, alkynyl groups containing three or more carbon atoms), and / or at least a portion of one or more precursors of the water-repellent additive may also contain polar functional groups. When both types of functional groups are present, a single precursor containing both types of functional groups contributing functional groups to the reaction product may be provided, and / or at least one precursor containing one of these types of functional groups but not the other types of functional groups contributing functional groups to the reaction product may be provided.

[0107] As described above, in some embodiments, the reaction to generate the water-repellent additive can be carried out between at least one precursor that contributes functional groups to the water-repellent additive and at least one precursor that does not contribute functional groups to the water-repellent additive. For example, the reaction may include catalyzing the reaction of the precursor that contributes functional groups to the water-repellent additive by exposing it to a precursor that does not contribute functional groups to the water-repellent additive. A non-limiting example of a class of precursors having the latter characteristic is an ammonium salt, and a non-limiting example of an ammonium salt is ammonium chloride. The reaction may also be catalyzed by heat, light (e.g., UV light), moisture, and / or a catalyst.

[0108] As described elsewhere herein, some filter media and / or nonwovens may contain resins. Some suitable resins may also be water-repellent additives as described above, and some resins may not be water-repellent additives as described above. In some embodiments, the resin may be water-repellent but may not contain the water-repellent functional groups described above. The resin may also be water-repellent and contain water-repellent functional groups. For example, in some embodiments, the filter media and / or nonwovens contain a first type of resin and a second type of resin. Further details regarding some suitable resins are provided below.

[0109] When present, the resin may constitute various suitable amounts of the filter media and / or nonwoven fiber web to which it is positioned. In some embodiments, the resin constitutes greater than or equal to 0% by weight, greater than or equal to 0.1% by weight, greater than or equal to 0.2% by weight, greater than or equal to 0.5% by weight, greater than or equal to 0.75% 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 7.5% by weight, greater than or equal to 10% by weight, greater than or equal to 12.5% ​​by weight, greater than or equal to 15% by weight, greater than or equal to 20% by weight, greater than or equal to 25% by weight, greater than or equal to 30% by weight, greater than or equal to 35% by weight, greater than or equal to 40% by weight, or greater than or equal to 45% by weight. In some embodiments, the resin constitutes 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 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 2% 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 0.2% by weight, or less than or equal to 0.1% by weight. Combinations of the above ranges are also possible (e.g., resin of type 1, greater than or equal to 0% by weight and less than or equal to 50% by weight, greater than or equal to 0% by weight and less than or equal to 35% by weight, greater than or equal to 1% by weight and less than or equal to 35% by weight, or greater than or equal to 0.5% by weight and less than or equal to 5% by weight). Other ranges are also possible. In addition, in some embodiments, the filter media and / or nonwoven fiber web also contain 0% by weight of resin.

[0110] When the filter media contains two or more resins, each resin may independently constitute an amount within one or more of the aforementioned ranges for the filter media. For example, in some embodiments, the filter media and / or nonwoven fiber web contains greater than 0% by weight and less than 50% by weight of a first type of resin (e.g., greater than or equal to 0.5% by weight and less than or equal to 5% by weight of a first type of resin) and / or greater than 0% by weight and less than 50% by weight of a second type of resin (e.g., greater than or equal to 0.5% by weight and less than or equal to 5% by weight of a second type of resin). In some embodiments, the total resin content of the filter media is within one or more of the aforementioned ranges.

[0111] The filter media described herein can comprise a variety of suitable resins. Non-limiting examples of such resins include latex, acrylic polymers, epoxy resins, phenolic polymers, silicones, poly(esters), poly(amides), poly(imides), poly(urethanes), poly(urea), poly(aromatic polyamides), and copolymers thereof. Non-limiting examples of suitable copolymers include binary copolymers, ternary copolymers, and quaternary copolymers. Furthermore, the arrangement of repeating units within the resin of a copolymer can generally be selected as desired. To provide non-limiting examples, suitable resins may include random copolymers, alternating copolymers, periodic copolymers, statistical copolymers, block copolymers, regular block copolymers, stereoblock copolymers, graded copolymers, and / or graft copolymers. The filter may also comprise two or more different resins. According to some embodiments, certain resins may not be present in the filter media. For example, in some embodiments, the filter media does not contain silicone-based resins. In some embodiments, the resin (e.g., any resin present in a nonwoven fiber web) is silicone-free.

[0112] In some embodiments, the filter medium comprises a resin that is a fluorinated resin. The fluorinated resin can be provided alone, in combination with another fluorinated resin, and / or in combination with a non-fluorinated resin. In some embodiments, the filter medium comprises a fluorinated resin that is also a water-repellent additive. The fluorinated resin may comprise fluorinated repeating units. For example, in some embodiments, the fluorinated resin is one of the resin types described in the preceding paragraphs and comprises fluorinated repeating units. Further non-limiting examples of suitable repeating units include polymerized vinylidene fluoride repeating units, polymerized tetrafluoroethylene repeating units, polymerized hexafluoropropylene repeating units, polymerized vinyl fluoride repeating units, polymerized perfluorocycloolefin repeating units, polymerized trifluorochloroethylene repeating units, polymerized perfluoropropyl vinyl ether repeating units, and polymerized perfluoromethyl vinyl ether repeating units. In some embodiments, the filter medium comprises a fluorinated resin that is a homopolymer, such as poly(tetrafluoroethylene) and / or poly(vinylidene fluoride). In some embodiments, the fluorinated repeating units do not contain fluorinated side chains. In other words, some fluorinated resins may contain fluorine atoms directly bonded to the main chain and not fluorine atoms bonded to any present side chains. Other fluorinated resins may contain fluorinated side chains.

[0113] When present, the fluorinated repeating unit can be the only repeating unit present in the fluorinated resin (in other words, the fluorinated resin can be a homopolymer) or the fluorinated repeating unit can be copolymerized with one or more other non-fluorinated repeating units (in other words, the fluorinated resin can be a copolymer). Non-limiting examples of suitable types of non-fluorinated repeating units that can be copolymerized with the fluorinated repeating unit include polymerized non-fluorinated epoxy repeating units, polymerized non-fluorinated carbamate repeating units, polymerized non-fluorinated ester repeating units, and polymerized non-fluorinated acrylic repeating units. In some embodiments, the fluorinated resin is a poly(vinylidene fluoride)-acrylic copolymer (i.e., a copolymer comprising vinylidene fluoride repeating units and non-fluorinated acrylic repeating units).

[0114] When the filter media contains a fluorinated resin (e.g., a poly(vinylidene fluoride)-acrylic acid copolymer), the fluorinated repeating unit can comprise various suitable amounts of the resin. In some embodiments, the fluorinated repeating unit comprises 30% or more, 35% or more, 40% or more, 45% or more, 50% or more, 55% or more, 60% or more, 65% or more, 70% or more, 75% or more, 80% or more, 85% or more, 90% or more, or 95% or more of the resin. In some embodiments, the fluorinated repeating unit comprises less than or equal to 100% by weight, 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, or less than or equal to 40% by weight, or less than or equal to 35% by weight. Combinations of the above ranges are also possible (e.g., greater than or equal to 30% by weight and less than or equal to 100% by weight, or greater than or equal to 50% by weight and less than or equal to 100% by weight). Other ranges are also possible. In some embodiments, the fluorinated repeating unit similarly comprises 100% by weight of the resin.

[0115] In some embodiments, the filter medium comprises a resin having one or more of the fluorinated repeating units in the above range, and may also comprise additional resins (which may each independently contain or not contain fluorinated repeating units). In some embodiments, the filter medium comprises two or more resins (at least one, but not necessarily all, of which contain fluorinated repeating units), and all resins in the filter medium simultaneously have one or more of the fluorinated repeating units in the above range.

[0116] The resin may also be free of fluorinated repeating units and / or unfluorinated.

[0117] As described elsewhere herein, in some embodiments, the filter media comprises a nonwoven fiber web. The nonwoven fiber web can be a layer in which one or more of the aforementioned additives and / or resins are positioned, and / or on which one or more of the aforementioned additives and / or resins (e.g., in the form of a coating) are disposed. The nonwoven fiber web can be used as a primary filter layer. Non-limiting examples of nonwoven fiber webs suitable for this purpose include wet-laid fiber webs, non-wet-laid fiber webs, and combinations thereof. Further details regarding some nonwoven fiber webs suitable for use as primary filter layers are provided below.

[0118] The nonwoven fiber web described herein can have a variety of suitable average fiber diameters. In some embodiments, the average fiber diameter of the fibers in the nonwoven fiber web is greater than or equal to 0.1 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 0.6 micrometers, greater than or equal to 0.75 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 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 17.5 micrometers, greater than or equal to 20 micrometers, greater than or equal to 22.5 micrometers, greater than or equal to 25 micrometers, greater than or equal to 27.5 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 implementations, the average fiber diameter of the fibers in the nonwoven fiber web is 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 27.5 micrometers, less than or equal to 25 micrometers, less than or equal to 22.5 micrometers, less than or equal to 20 micrometers, less than or equal to 17.5 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, 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 50 micrometers, greater than or equal to 0.3 micrometers and less than or equal to 25 micrometers, or greater than or equal to 0.5 micrometers and less than or equal to 10 micrometers). Other ranges are also possible.

[0119] When the filter medium comprises two or more nonwoven fiber webs, each nonwoven fiber web may independently have an average fiber diameter within one or more of the above ranges.

[0120] The nonwoven fiber web described herein can have a variety of suitable average fiber lengths. In some embodiments, the average fiber length of the fibers in the nonwoven fiber web is greater than or equal to 0.001 inches, greater than or equal to 0.002 inches, greater than or equal to 0.003 inches, greater than or equal to 0.004 inches, greater than or equal to 0.005 inches, greater than or equal to 0.01 inches, greater than or equal to 0.05 inches, greater than or equal to 0.1 inches, greater than or equal to 0.15 inches, greater than or equal to 0.2 inches, greater than or equal to 0.25 inches, greater than or equal to 0.3 inches, greater than or equal to 0.35 inches, greater than or equal to 0.4 inches, greater than or equal to 0.45 inches, greater than or equal to 0.5 inches, greater than or equal to 0.55 inches, greater than or equal to 0.6 inches, greater than or equal to 0.65 inches, greater than or equal to 0.7 inches, greater than or equal to 0.75 inches, greater than or equal to 0.8 inches, greater than or equal to 0.85 inches, or greater than or equal to 0.9 inches. In some implementations, the average fiber length of the fibers in the nonwoven fiber web is less than or equal to 1 inch, less than or equal to 0.95 inches, less than or equal to 0.9 inches, less than or equal to 0.85 inches, less than or equal to 0.8 inches, less than or equal to 0.75 inches, less than or equal to 0.7 inches, less than or equal to 0.65 inches, less than or equal to 0.6 inches, less than or equal to 0.55 inches, less than or equal to 0.5 inches, less than or equal to 0.45 inches, less than or equal to 0.4 inches, less than or equal to 0.35 inches, less than or equal to 0.3 inches, less than or equal to 0.25 inches, less than or equal to 0.2 inches, less than or equal to 0.15 inches, less than or equal to 0.1 inches, less than or equal to 0.05 inches, or less than or equal to 0.01 inches. Combinations of the above ranges are also possible (e.g., greater than or equal to 0.001 inches and less than or equal to 1 inch, greater than or equal to 0.002 inches and less than or equal to 0.75 inches, or greater than or equal to 0.004 inches and less than or equal to 0.5 inches). Other ranges are also possible.

[0121] When the filter medium comprises two or more nonwoven fiber webs, each nonwoven fiber web may independently have an average fiber length within one or more of the above ranges.

[0122] In some embodiments, the nonwoven fiber web comprises glass fibers. The glass fibers can constitute various suitable amounts in the nonwoven fiber web. In some embodiments, the glass fibers constitute ≥0% by weight, ≥0% by weight, ≥1% by weight, ≥2% by weight, ≥5% by weight, ≥7.5% by weight, ≥10% by weight, ≥15% by weight, ≥20% by weight, ≥25% by weight, ≥30% by weight, ≥40% by weight, ≥50% by weight, ≥60% by weight, or ≥80% by weight of the fibers in the nonwoven fiber web. In some embodiments, glass fiber constitutes less than or equal to 100% by weight, less than or equal to 80% 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 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 100% by weight, or greater than 0% by weight and less than or equal to 100% by weight). Other ranges are also possible. In some embodiments, glass fiber constitutes exactly 0% by weight of the fibers in the nonwoven fiber web. In some embodiments, glass fiber constitutes exactly 100% by weight of the fibers in the nonwoven fiber web.

[0123] When the filter medium comprises two or more nonwoven fiber webs, each nonwoven fiber web may independently have one or more amounts of glass fibers within the range described above.

[0124] In some embodiments, the nonwoven fiber web comprises microglass fibers. According to some embodiments, the nonwoven fiber web comprises fine microglass fibers. According to some embodiments, the nonwoven fiber web comprises microglass fibers with a medium diameter. According to some embodiments, the nonwoven fiber web comprises coarse glass fibers (e.g., chopped strand glass fibers).

[0125] Microglass fibers can include those drawn from a bushing tip and further subjected to flame blowing or rotary spinning processes. In some cases, microglass fibers can be manufactured using a remelting method. Microglass fibers can be those in which alkali metal oxides (e.g., sodium oxide, magnesium oxide) constitute 10% to 20% by weight of the fiber. Such fibers can have relatively low melting and processing temperatures. Non-limiting examples of microglass fibers include B, E, S, M, and C glass fibers (e.g., Lauscha C glass fiber, JM 253 C glass fiber) according to the Nomenclature Committee of TIMA Inc., March 1993, page 45, and non-persistent glass fibers (e.g., fibers configured to completely dissolve in the fluid present in the human lungs within 40 days or less, such as Johns Manville 481 fiber). It should be understood that microglass fibers present in nonwoven fiber webs may include one or more types of microglass fibers described herein.

[0126] When present, microglass fibers can constitute various suitable amounts in the nonwoven fiber web. In some embodiments, microglass fibers constitute ≥1% by weight, ≥2% by weight, ≥5% by weight, ≥7.5% by weight, ≥10% by weight, ≥15% by weight, ≥20% by weight, ≥25% by weight, ≥30% by weight, ≥40% by weight, ≥50% by weight, ≥60% by weight, or ≥80% by weight of the fibers in the nonwoven fiber web. In some embodiments, microglass fibers constitute ≤100% by weight, ≤80% by weight, ≤60% by weight, ≤50% by weight, ≤40% by weight, ≤30% by weight, ≤25% by weight, ≤20% by weight, ≤15% by weight, ≤10% by weight, ≤7.5% by weight, ≤5% by weight, or ≤2% by weight of the fibers in the nonwoven fiber web. Combinations of the above ranges are also possible (e.g., greater than or equal to 1% by weight and less than or equal to 100% by weight). Other ranges are also possible. In some embodiments, the glass fiber comprises exactly 100% by weight of the fibers in the nonwoven fiber web.

[0127] When a nonwoven fiber web comprises two or more types of microglass fibers, each type of microglass fiber may independently constitute one or more of the amounts within the aforementioned ranges of the nonwoven fiber web. Furthermore, in some embodiments, the total amount of microglass fibers in the nonwoven fiber web may be within one or more of the aforementioned ranges. Similarly, when the filter media comprises two or more nonwoven fiber webs, each type of microglass fiber may independently constitute one or more of the amounts within the aforementioned ranges of each nonwoven fiber web and / or the total amount of microglass fibers in each nonwoven fiber web may independently be within one or more of the aforementioned ranges.

[0128] When present, microglass fibers can have a variety of suitable average diameters. In some embodiments, the average diameter of the microglass fibers in the nonwoven fiber web is greater than or equal to 0.1 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 0.35 micrometers, greater than or equal to 0.4 micrometers, greater than or equal to 0.45 micrometers, greater than or equal to 0.5 micrometers, greater than or equal to 0.55 micrometers, greater than or equal to 0.6 micrometers, greater than or equal to 0.65 micrometers, greater than or equal to 0.7 micrometers, greater than or equal to 0.75 micrometers, greater than or equal to 0.8 micrometers, greater than or equal to 0.85 micrometers, greater than or equal to 0.9 micrometers, greater than or equal to 0.95 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 5 micrometers, or greater than or equal to 7.5 micrometers. In some implementations, the average diameter of the microglass fibers in the nonwoven fiber web is less than or equal to 10 micrometers, less than or equal to 7.5 micrometers, less than or equal to 6 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 0.95 micrometers, less than or equal to 0.9 micrometers, less than or equal to 0.85 micrometers, less than or equal to 0.8 micrometers, less than or equal to 0.75 micrometers, less than or equal to 0.7 micrometers, less than or equal to 0.65 micrometers, less than or equal to 0.6 micrometers, less than or equal to 0.55 micrometers, less than or equal to 0.5 micrometers, less than or equal to 0.45 micrometers, less than or equal to 0.4 micrometers, less than or equal to 0.35 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 10 micrometers, greater than or equal to 0.1 micrometers and less than or equal to 1 micrometer, greater than or equal to 0.2 micrometers and less than or equal to 0.8 micrometers, greater than or equal to 0.4 micrometers and less than or equal to 0.8 micrometers, greater than or equal to 0.2 micrometers and less than or equal to 0.55 micrometers, greater than or equal to 0.2 micrometers and less than or equal to 0.4 micrometers, greater than or equal to 0.4 micrometers and less than or equal to 1 micrometer, greater than or equal to 0.5 micrometers and less than or equal to 1 micrometer, greater than 1 micrometer and less than or equal to 6 micrometers, greater than or equal to 2 micrometers and less than or equal to 10 micrometers, or greater than or equal to 2.5 micrometers and less than or equal to 10 micrometers). Other ranges are also possible.

[0129] When a nonwoven fiber web comprises two or more types of microglass fibers, each type of microglass fiber may have an average diameter within one or more of the aforementioned ranges. Furthermore, in some embodiments, all microglass fibers in the nonwoven fiber web simultaneously have an average diameter within one or more of the aforementioned ranges. Similarly, when the filter medium comprises two or more nonwoven fiber webs, each nonwoven fiber web may independently contain microglass fibers with an average diameter within one or more of the aforementioned ranges (independently one or more types, or simultaneously all types).

[0130] When present, microglass fibers can have a variety of suitable average fiber lengths. In some embodiments, the average fiber length of the microglass fibers is greater than or equal to 0.001 inches, greater than or equal to 0.002 inches, greater than or equal to 0.003 inches, greater than or equal to 0.004 inches, greater than or equal to 0.006 inches, greater than or equal to 0.008 inches, greater than or equal to 0.01 inches, greater than or equal to 0.025 inches, greater than or equal to 0.05 inches, greater than or equal to 0.075 inches, greater than or equal to 0.1 inches, greater than or equal to 0.2 inches, greater than or equal to 0.3 inches, greater than or equal to 0.4 inches, greater than or equal to 0.5 inches, greater than or equal to 0.6 inches, greater than or equal to 0.75 inches, or greater than or equal to 0.9 inches. In some implementations, the average fiber length of the microglass fibers is less than or equal to 1 inch, less than or equal to 0.9 inches, less than or equal to 0.75 inches, less than or equal to 0.6 inches, less than or equal to 0.5 inches, less than or equal to 0.4 inches, less than or equal to 0.3 inches, less than or equal to 0.2 inches, less than or equal to 0.1 inches, less than or equal to 0.075 inches, less than or equal to 0.05 inches, less than or equal to 0.025 inches, less than or equal to 0.01 inches, less than or equal to 0.008 inches, less than or equal to 0.006 inches, less than or equal to 0.004 inches, less than or equal to 0.003 inches, less than or equal to 0.002 inches, or less than or equal to 0.001 inches. Combinations of the above ranges are also possible (e.g., greater than or equal to 0.001 inches and less than or equal to 1 inch, greater than or equal to 0.003 inches and less than or equal to 0.75 inches, or greater than or equal to 0.01 inches and less than or equal to 0.5 inches). Other ranges are also possible.

[0131] When a nonwoven fiber web comprises two or more types of microglass fibers, each type of microglass fiber may independently have an average fiber length within one or more of the aforementioned ranges, and / or all microglass fibers in the first type of nonwoven fiber web may simultaneously have an average fiber length within one or more of the aforementioned ranges. Similarly, when a filter medium comprises two or more nonwoven fiber webs, each nonwoven fiber web may independently contain one or more types of microglass fibers with an average fiber length within one or more of the aforementioned ranges, and / or may contain microglass fibers with an overall average fiber length within one or more of the aforementioned ranges.

[0132] When present, microglass fibers can have a variety of suitable aspect ratios. In some implementations, the aspect ratio of the microglass fibers is greater than or equal to 100, greater than or equal to 150, greater than or equal to 200, greater than or equal to 300, greater than or equal to 400, greater than or equal to 500, greater than or equal to 750, greater than or equal to 1000, greater than or equal to 1500, greater than or equal to 2000, greater than or equal to 2000, greater than or equal to 7000, greater than or equal to 8000, greater than or equal to 9000, greater than or equal to 10000, greater than or equal to 20000, greater than or equal to 30000, greater than or equal to 40000, greater than or equal to 50000, greater than or equal to 60000, greater than or equal to 70000, greater than or equal to 80000, or greater than or equal to 90000. In some embodiments, the aspect ratio of the microglass fibers is less than or equal to 100,000, less than or equal to 90,000, less than or equal to 80,000, less than or equal to 70,000, less than or equal to 60,000, less than or equal to 50,000, less than or equal to 40,000, less than or equal to 30,000, less than or equal to 20,000, less than or equal to 10,000, less than or equal to 9,000, less than or equal to 8,000, less than or equal to 7,000, less than or equal to 6,000, less than or equal to 5,000, less than or equal to 4,000, less than or equal to 3,500, less than or equal to 3,000, less than or equal to 2,500, less than or equal to 2,000, less than or equal to 1,500, less than or equal to 1,000, less than or equal to 750, less than or equal to 500, less than or equal to 400, less than or equal to 300, less than or equal to 200, or less than or equal to 150. Combinations of the above ranges are also possible (e.g., greater than or equal to 100 and less than or equal to 100000, greater than or equal to 100 and less than or equal to 10000, greater than or equal to 200 and less than or equal to 2500, or greater than or equal to 300 and less than or equal to 1000). Other ranges are also possible.

[0133] When a nonwoven fiber web comprises two or more types of microglass fibers, each type of microglass fiber may independently have an aspect ratio within one or more of the aforementioned ranges, and / or all microglass fibers in the nonwoven fiber web may simultaneously have an aspect ratio within one or more of the aforementioned ranges. Similarly, when a filter medium comprises two or more nonwoven fiber webs, each nonwoven fiber web may independently comprise one or more types of microglass fibers with aspect ratios within one or more of the aforementioned ranges and / or may comprise glass fibers with an overall aspect ratio within one or more of the aforementioned ranges.

[0134] In some embodiments, the nonwoven fiber web comprises particularly advantageous amounts of a specific type of microglass fibers. For example, in some embodiments, the nonwoven fiber web comprises the following amounts of fine microglass fibers (e.g., with an average diameter of less than or equal to 1 micrometer (e.g., greater than or equal to 0.1 micrometers and less than or equal to 1 micrometer, greater than or equal to 0.2 micrometers and less than or equal to 0.8 micrometers, or greater than or equal to 0.4 micrometers and less than or equal to 0.8 micrometers) in the nonwoven fiber web: greater than or equal to 0 wt%, greater than 0 wt%, greater than or equal to 1.5 wt%, greater than or equal to 2 wt%, greater than or equal to 5 wt%, greater than or equal to 7.5 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 30 wt%, greater than or equal to 40 wt%, greater than or equal to 50 wt%, greater than or equal to 60 wt%, greater than or equal to 70 wt%, greater than or equal to 75 wt%, greater than or equal to 80 wt%, or greater than or equal to 90 wt%. In some embodiments, the nonwoven fiber web comprises fine microglass fibers in the following amounts: 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 75 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 15 wt%, less than or equal to 10 wt%, less than or equal to 7.5 wt%, less than or equal to 5 wt%, less than or equal to 2 wt%, or less than or equal to 1.5 wt%. 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 0% by weight and less than or equal to 75% by weight, greater than or equal to 0% by weight and less than or equal to 60% by weight, greater than or equal to 0% by weight and less than or equal to 95% by weight, greater than or equal to 0% by weight and less than or equal to 75% by weight, greater than or equal to 0% by weight and less than or equal to 60% by weight, greater than or equal to 1.5% by weight and less than or equal to 100% by weight, 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 60% by weight, greater than or equal to 10% by weight and less than or equal to 20% by weight, or greater than or equal to 40% by weight and less than or equal to 50% by weight). Other ranges are also possible. In some embodiments, the fine microglass fibers constitute exactly 0% by weight of the fibers in the nonwoven fiber web.

[0135] When the filter medium comprises two or more nonwoven fiber webs, each nonwoven fiber web may independently contain an amount of fine microglass fibers within one or more of the above-mentioned range.

[0136] In some embodiments, the nonwoven fiber web comprises the following amounts of microglass fibers having a medium diameter (e.g., an average diameter greater than 1 micrometer and less than or equal to 6 micrometers (e.g., greater than or equal to 2 micrometers and less than or equal to 6 micrometers or greater than or equal to 3 micrometers and less than or equal to 5 micrometers) in the nonwoven fiber web: greater than 0 wt%, greater than or equal to 1.5 wt%, greater than or equal to 2 wt%, greater than or equal to 5 wt%, greater than or equal to 7.5 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 30 wt%, greater than or equal to 40 wt%, greater than or equal to 50 wt%, greater than or equal to 60 wt%, greater than or equal to 70 wt%, greater than or equal to 80 wt%, or greater than or equal to 90 wt%. In some embodiments, the nonwoven fiber web comprises microglass fibers of medium diameter in the following amounts as fibers in the nonwoven fiber web: 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 15 wt%, less than or equal to 10 wt%, less than or equal to 7.5 wt%, less than or equal to 5 wt%, less than or equal to 2 wt%, or less than or equal to 1.5 wt%. Combinations of the above ranges are also possible (e.g., greater than 0 wt% and less than or equal to 95 wt%, greater than or equal to 20 wt% and less than or equal to 80 wt%, greater than or equal to 30 wt% and less than or equal to 70 wt%, greater than or equal to 30 wt% and less than or equal to 40 wt%, or greater than or equal to 60 wt% and less than or equal to 70 wt%). Other ranges are also possible.

[0137] When the filter media comprises two or more nonwoven fiber webs, each nonwoven fiber web may independently contain an amount of microglass fibers of medium diameter within one or more of the above-mentioned ranges.

[0138] In some embodiments, the nonwoven fiber web comprises coarse glass fibers (e.g., microglass fibers and / or chopped glass fibers). When present, the coarse glass fibers can have a variety of suitable average diameters. In some embodiments, the average diameter of the coarse glass fibers in the nonwoven fiber web is greater than 6 micrometers, greater than or equal to 6.25 micrometers, greater than or equal to 6.5 micrometers, greater than or equal to 7 micrometers, greater than or equal to 8 micrometers, greater than or equal to 10 micrometers, greater than or equal to 12 micrometers, greater than or equal to 15 micrometers, greater than or equal to 18 micrometers, greater than or equal to 20 micrometers, greater than or equal to 23 micrometers, or greater than or equal to 25 micrometers. In some embodiments, the average diameter of the coarse glass fibers in the nonwoven fiber web is less than or equal to 30 micrometers, less than or equal to 28 micrometers, less than or equal to 25 micrometers, less than or equal to 23 micrometers, less than or equal to 20 micrometers, less than or equal to 18 micrometers, less than or equal to 15 micrometers, less than or equal to 14 micrometers, less than or equal to 13 micrometers, less than or equal to 12 micrometers, less than or equal to 11 micrometers, less than or equal to 10 micrometers, less than or equal to 9 micrometers, less than or equal to 8 micrometers, or less than or equal to 7 micrometers. Combinations of the above ranges are also possible (e.g., greater than 6 micrometers and less than or equal to 30 micrometers, greater than 6 micrometers and less than or equal to 14 micrometers, greater than 6 micrometers and less than or equal to 10 micrometers, or greater than 6 micrometers and less than or equal to 8 micrometers). Other ranges are also possible.

[0139] When present, coarse glass fibers can be present in any suitable amount. In some embodiments, the nonwoven fiber web contains coarse glass fibers in the following amounts as fibers in the nonwoven fiber web: greater than or equal to 0% by weight, greater than 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 7.5% by weight, greater than or equal to 10% by weight, greater than or equal to 15% by weight, greater than or equal to 20% by weight, greater than or equal to 25% by weight, greater than or equal to 30% by weight, greater than or equal to 35% by weight, greater than or equal to 40% by weight, greater than or equal to 45% by weight, greater than or equal to 50% by weight, or greater than or equal to 55% by weight. In some embodiments, the nonwoven fiber web comprises the following amounts of coarse glass fibers in the nonwoven fiber web: 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 7.5 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 the above ranges are also possible (e.g., greater than or equal to 0 wt% and less than or equal to 60 wt%, greater than 0 wt% and less than or equal to 60 wt%, greater than or equal to 5 wt% and less than or equal to 25 wt%, or greater than or equal to 10 wt% and less than or equal to 20 wt%). Other ranges are also possible. In some embodiments, the coarse glass fibers constitute exactly 0 wt% of the fibers in the nonwoven fiber web.

[0140] When the filter medium comprises two or more nonwoven fiber webs, each nonwoven fiber web may independently contain an amount of coarse fiber within one or more of the above-mentioned range.

[0141] In some embodiments, the filter medium may comprise one, two, three, or more types of glass fibers (e.g., two or all of the following: fine microglass fibers, microglass fibers with medium diameter, and coarse microglass fibers). In embodiments comprising two or more types of glass fibers (e.g., both fine microglass fibers and microglass fibers with medium diameter, both fine microglass fibers and coarse glass fibers, both microglass fibers with medium diameter and coarse glass fibers, or all three of the above types), the glass fibers falling into the category described by the relatively large diameter may have a larger average diameter than the glass fibers falling into the category described by the relatively small diameter. The difference in fiber diameter between the existing groups of microglass fibers can be large enough that two or more groups of fibers can be easily distinguished by a microscope.

[0142] In some embodiments, the nonwoven fiber web comprises coarse glass fibers including chopped glass fibers. In some embodiments, the coarse glass fibers present in the nonwoven fiber web are chopped glass fibers. Chopped glass fibers can comprise chopped glass fibers produced by drawing molten glass from a sleeve tip into continuous fibers and then cutting the continuous fibers into short fibers. In some embodiments, the nonwoven fiber web comprises chopped glass fibers in a relatively small amount of alkali metal oxides (e.g., sodium oxide, magnesium oxide). The nonwoven fiber web may also comprise chopped glass fibers containing a relatively large amount of calcium oxide and / or alumina (Al2O3). In some embodiments, the nonwoven fiber web comprises S-glass fibers containing about 10% by weight of magnesium oxide. It should be understood that the chopped glass fibers present in the nonwoven fiber web may comprise one or more types of chopped glass fibers described herein.

[0143] When present, chopped glass fibers can constitute various suitable amounts in the nonwoven fiber web. In some embodiments, chopped glass fibers constitute ≥0% by weight, ≥0% by weight, ≥1% by weight, ≥2% by weight, ≥5% by weight, ≥7.5% by weight, ≥10% by weight, ≥15% by weight, ≥20% by weight, ≥25% by weight, ≥30% by weight, ≥35% by weight, ≥40% by weight, ≥45% by weight, ≥50% by weight, or ≥55% by weight. In some embodiments, chopped glass fibers constitute 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 60% by weight, greater than or equal to 0% by weight and less than or equal to 60% by weight, greater than or equal to 5% by weight and less than or equal to 25% by weight, greater than or equal to 10% by weight and less than or equal to 20% by weight, greater than or equal to 0% by weight and less than or equal to 50% by weight, or greater than or equal to 0% by weight and less than or equal to 50% by weight). Other ranges are also possible. In some embodiments, chopped glass fibers constitute exactly 0% by weight of the fibers in the nonwoven fiber web.

[0144] In some embodiments, the nonwoven fiber web comprises two or more types of chopped glass fibers. For example, in some embodiments, the nonwoven fiber web comprises a first type of chopped glass fibers and a second type of chopped glass fibers. When the nonwoven fiber web comprises two or more types of chopped glass fibers, each type of chopped glass fiber may independently constitute an amount within one or more of the aforementioned ranges for the nonwoven fiber web. Furthermore, in some embodiments, the total amount of chopped glass fibers in the nonwoven fiber web may be within one or more of the aforementioned ranges. Similarly, when the filter media comprises two or more nonwoven fiber webs, each type of chopped glass fibers may independently constitute an amount within one or more of the aforementioned ranges for each nonwoven fiber web and / or the total amount of chopped glass fibers in each nonwoven fiber web may independently be within one or more of the aforementioned ranges.

[0145] When present, chopped glass fibers can have a variety of suitable average diameters. In some embodiments, the nonwoven fiber web comprises chopped glass fibers with the following average diameters: greater than 6 micrometers, greater than or equal to 6.25 micrometers, greater than or equal to 6.5 micrometers, greater than or equal to 7 micrometers, greater than or equal to 8 micrometers, greater than or equal to 10 micrometers, greater than or equal to 12.5 micrometers, greater than or equal to 14 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 22 micrometers, or greater than or equal to 25 micrometers. In some embodiments, the nonwoven fiber web comprises chopped glass fibers with the following average diameters: less than or equal to 30 micrometers, less than or equal to 28 micrometers, less than or equal to 25 micrometers, less than or equal to 23 micrometers, less than or equal to 20 micrometers, less than or equal to 18 micrometers, less than or equal to 15 micrometers, less than or equal to 14 micrometers, less than or equal to 13 micrometers, less than or equal to 12 micrometers, less than or equal to 11 micrometers, less than or equal to 10 micrometers, less than or equal to 9 micrometers, less than or equal to 8 micrometers, or less than or equal to 7 micrometers. Combinations of the above ranges are also possible (e.g., greater than 6 micrometers and less than or equal to 30 micrometers, greater than 6 micrometers and less than or equal to 14 micrometers, or greater than 6 micrometers and less than or equal to 10 micrometers). Other ranges are also possible.

[0146] When a nonwoven fiber web comprises two or more types of chopped glass fibers, each type of chopped glass fiber may have an average diameter within one or more of the aforementioned ranges. Furthermore, in some embodiments, all chopped glass fibers in the nonwoven fiber web simultaneously have an average diameter within one or more of the aforementioned ranges. Similarly, when the filter media comprises two or more nonwoven fiber webs, each nonwoven fiber web may independently contain chopped glass fibers with an average diameter within one or more of the aforementioned ranges (independently of one or more types, or all types simultaneously).

[0147] When present, chopped glass fibers can have a variety of suitable average lengths. In some embodiments, the nonwoven fiber web comprises chopped glass fibers having the following average lengths: greater than or equal to 0.004 inches, greater than or equal to 0.005 inches, greater than or equal to 0.0075 inches, greater than or equal to 0.01 inches, greater than or equal to 0.02 inches, greater than or equal to 0.05 inches, greater than or equal to 0.075 inches, greater than or equal to 0.1 inches, greater than or equal to 0.2 inches, greater than or equal to 0.5 inches, greater than or equal to 0.75 inches, greater than or equal to 1 inch, greater than or equal to 1.25 inches, greater than or equal to 1.5 inches, greater than or equal to 2 inches, or greater than or equal to 2.5 inches. In some embodiments, the nonwoven fiber web comprises chopped glass fibers having the following average lengths: less than or equal to 3 inches, less than or equal to 2.5 inches, less than or equal to 2 inches, less than or equal to 1.5 inches, less than or equal to 1.25 inches, less than or equal to 1 inch, less than or equal to 0.75 inches, less than or equal to 0.5 inches, less than or equal to 0.2 inches, less than or equal to 0.1 inches, less than or equal to 0.075 inches, less than or equal to 0.05 inches, less than or equal to 0.02 inches, less than or equal to 0.01 inches, less than or equal to 0.0075 inches, or less than or equal to 0.005 inches. Combinations of the above ranges are also possible (e.g., greater than or equal to 0.004 inches and less than or equal to 3 inches, greater than or equal to 0.004 inches and less than or equal to 2 inches, or greater than or equal to 0.05 inches and less than or equal to 3 inches). Other ranges are also possible.

[0148] When a nonwoven fiber web comprises two or more types of chopped glass fibers, each type of chopped glass fiber may have an average length within one or more of the aforementioned ranges. Furthermore, in some embodiments, all chopped glass fibers in the nonwoven fiber web simultaneously have an average length within one or more of the aforementioned ranges. Similarly, when a filter medium comprises two or more nonwoven fiber webs, each nonwoven fiber web may independently contain chopped glass fibers with an average length within one or more of the aforementioned ranges (independently of one or more types, or all types simultaneously).

[0149] In some embodiments, the nonwoven fiber web comprises natural fibers. When present, natural fibers can constitute various suitable amounts in the nonwoven fiber web. In some embodiments, natural fibers constitute 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, 40% or more by weight, 50% or more by weight, 60% or more by weight, or 80% or more by weight of the fibers in the nonwoven fiber web. In some embodiments, natural fibers constitute less than or equal to 100% by weight, less than or equal to 80% 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 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 100% by weight, or greater than 0% by weight and less than or equal to 100% by weight). Other ranges are also possible. In some embodiments, natural fibers constitute exactly 0% by weight of the fibers in the nonwoven fiber web. In some embodiments, natural fibers constitute exactly 100% by weight of the fibers in the nonwoven fiber web.

[0150] When a nonwoven fiber web comprises two or more types of natural fibers, each type of natural fiber may independently constitute an amount within one or more of the aforementioned ranges in the nonwoven fiber web. Furthermore, in some embodiments, the total amount of natural fibers in the nonwoven fiber web may be within one or more of the aforementioned ranges. Similarly, when a filter medium comprises two or more nonwoven fiber webs, each type of natural fiber may independently constitute an amount within one or more of the aforementioned ranges in each nonwoven fiber web and / or the total amount of natural fibers in each nonwoven fiber web may independently be within one or more of the aforementioned ranges.

[0151] One example of a natural fiber is a natural cellulose fiber. When a fiber web contains natural cellulose fibers, the natural cellulose fibers can be wood (e.g., cedar) fibers, such as cork fibers and / or hardwood fibers. Other examples of natural cellulose fibers are also possible (e.g., nanocellulose fibers, such as nanofibrillated fibers and / or fibrous cellulose nanocrystals; microfibrillated cellulose). The fiber web may also contain wool.

[0152] Exemplary cork fibers include fibers obtained from: mercerized southern pine (“mercerized southern pine fiber or HPZ fiber”), northern bleached cork kraft paper (e.g., fiber obtained from Robur Flash oak (“Oak Flash fiber”), southern bleached cork kraft paper (e.g., fiber obtained from Brunswick pine (“Brunswick pine fiber”)), and / or chemically treated mechanical pulp (“CTMP fiber”). For example, HPZ fiber may be obtained from Buckeye Technologies, Inc. of Memphis, Tennessee; Robur Flash oak fiber may be obtained from Rottneros AB of Stockholm, Sweden; and Brunswick pine fiber may be obtained from Georgia-Pacific of Atlanta, Georgia.

[0153] Exemplary hardwood fibers include fibers obtained from eucalyptus trees (“eucalyptus fiber”). Eucalyptus fiber is commercially available from, for example, (1) Suzano Group of Suzano, Brazil (“Suzano fiber”), (2) Group Portucel Soporcel of Cacia, Portugal (“Cacia fiber”), (3) Tembec, Inc. of Temiscaming, Quebec, Canada (“Tarascon fiber”), (4) Kartonimex Intercell of Düsseldorf, Germany (“Acacia fiber”), (5) Mead-Westvaco of Stamford, Connecticut (“Westvaco fiber”), and (6) Georgia-Pacific of Atlanta, Georgia (“Leaf River fiber”).

[0154] When present, natural fibers can have a variety of suitable average diameters. In some embodiments, the nonwoven fiber web comprises natural fibers with the following average diameters: 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 7.5 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 30 micrometers, or greater than or equal to 40 micrometers. In some embodiments, the nonwoven fiber web comprises natural fibers with the following average diameters: 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 7.5 micrometers, less than or equal to 5 micrometers, or less than or equal to 2 micrometers. Combinations of the above ranges are also possible (e.g., greater than or equal to 1 micrometer and less than or equal to 50 micrometers). Other ranges are also possible.

[0155] When a nonwoven fiber web comprises two or more types of natural fibers, each type of natural fiber may have an average diameter within one or more of the aforementioned ranges. Furthermore, in some embodiments, all natural fibers in the nonwoven fiber web simultaneously have an average diameter within one or more of the aforementioned ranges. Similarly, when the filter media comprises two or more nonwoven fiber webs, each nonwoven fiber web may independently contain natural fibers with an average diameter within one or more of the aforementioned ranges (independently of one or more types, or all types simultaneously).

[0156] In some embodiments, the nonwoven fiber web comprises synthetic fibers. Synthetic fibers can constitute various suitable amounts in the nonwoven fiber web. In some embodiments, synthetic fibers constitute ≥0% by weight, ≥0% by weight, ≥0.1% by weight, ≥0.5% by weight, ≥1% by weight, ≥2% by weight, ≥5% by weight, ≥7.5% by weight, ≥10% by weight, ≥15% by weight, ≥20% by weight, ≥25% by weight, ≥30% by weight, ≥40% by weight, ≥50% by weight, ≥60% by weight, or ≥80% by weight of the fibers in the nonwoven fiber web. In some embodiments, synthetic fibers constitute less than or equal to 100% by weight, less than or equal to 80% 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 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, less than or equal to 1% by weight, less than or equal to 0.5% by weight, or less than or equal to 0.1% 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, or greater than 0% by weight and less than or equal to 100% by weight). Other ranges are also possible. In some embodiments, synthetic fibers constitute exactly 0% by weight of the fibers in the nonwoven fiber web. In some embodiments, synthetic fibers constitute exactly 100% by weight of the fibers in the nonwoven fiber web.

[0157] When a nonwoven fiber web comprises two or more types of synthetic fibers, each type of synthetic fiber may independently constitute one or more of the amount of the nonwoven fiber web within the aforementioned ranges. Furthermore, in some embodiments, the total amount of synthetic fibers in the nonwoven fiber web may be within one or more of the aforementioned ranges. Similarly, when a filter medium comprises two or more nonwoven fiber webs, each type of synthetic fiber may independently constitute one or more of the amount of each nonwoven fiber web within the aforementioned ranges, and / or the total amount of synthetic fibers in each nonwoven fiber web may independently be within one or more of the aforementioned ranges.

[0158] Various suitable types of synthetic fibers can be used in the nonwoven fiber webs described herein. In some embodiments, the nonwoven fiber web comprises a single-component synthetic fiber. Non-limiting examples of suitable polymers that can be included in the synthetic fibers include: acrylic resins, poly(vinyl alcohol) (PVOH), poly(ester) (e.g., polyethylene terephthalate), poly(acrylonitrile), poly(olefin) (e.g., poly(ethylene), poly(propylene)), poly(vinylidene fluoride), poly(ether sulfone), poly(vinyl chloride), poly(amide), poly(imide), aromatic polyamides (e.g., meta-aromatic polyamide, para-aromatic polyamide), poly(etherimide), poly(ether ether ketone), liquid crystal polymers (e.g., poly(p-phenylene-2,6-benzobismuth subcarbonyl)). (azole); poly(ester) based liquid crystal polymers, such as fibers produced by polycondensation of 4-hydroxybenzoic acid and 6-hydroxynaphthalene-2-carboxylic acid, regenerated cellulose (e.g., lyocell, rayon), celluloid, cellulose acetate, carboxymethyl cellulose, the aforementioned copolymers, and the aforementioned blends.

[0159] According to some embodiments, the nonwoven fiber web may have a relatively low percentage of synthetic fibers other than fibrillated fibers (e.g., 5% or equal by weight, 3% or equal by weight, 1% or equal by weight, 0.5% or equal by weight, 0.1% or equal by weight, or 0% by weight, or any other range disclosed above). In some embodiments, the nonwoven fiber web may be substantially free of synthetic fibers other than fibrillated fibers (e.g., lyocell fibers). In some embodiments, the nonwoven fiber web is free of synthetic fibers other than fibrillated fibers (e.g., lyocell fibers).

[0160] In some embodiments, the nonwoven fiber web comprises synthetic fibers containing a relatively small amount (e.g., less than or equal to 2% by weight, less than or equal to 1% by weight, less than or equal to 0.5% by weight, less than or equal to 0.1% by weight, or 0% by weight) of polyvinyl alcohol. In some embodiments, this may be desirable because, in some cases, the presence of polyvinyl alcohol fibers can reduce the gamma value of the filter media containing polyvinyl alcohol fibers compared to substantially the same filter media without polyvinyl alcohol fibers. In some embodiments, the nonwoven fiber web may be substantially free of synthetic fibers containing polyvinyl alcohol. In some embodiments, the nonwoven fiber web is free of synthetic fibers containing polyvinyl alcohol.

[0161] When present, synthetic fibers (e.g., lyocell fibers) can have a variety of suitable average diameters. In some embodiments, the nonwoven 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 0.075 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 0.75 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 7.5 micrometers, greater than or equal to 10 micrometers, greater than or equal to 20 micrometers, greater than or equal to 50 micrometers, or greater than or equal to 75 micrometers. In some embodiments, the nonwoven fiber web comprises synthetic fibers having the following average diameters: 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 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 0.2 micrometers, less than or equal to 0.1 micrometers, less than or equal to 0.075 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). Other ranges are also possible.

[0162] When a nonwoven fiber web comprises two or more types of synthetic fibers, each type of synthetic fiber may have an average diameter within one or more of the aforementioned ranges. Furthermore, in some embodiments, all synthetic fibers in the nonwoven fiber web simultaneously have an average diameter within one or more of the aforementioned ranges. Similarly, when the filter media comprises two or more nonwoven fiber webs, each nonwoven fiber web may independently contain synthetic fibers with an average diameter within one or more of the aforementioned ranges (independently of one or more types, or all types simultaneously).

[0163] When present, synthetic fibers may include continuous and / or discontinuous fibers. Continuous fibers can be produced by “continuous” fiber forming processes such as meltblowing or spunbonding and typically have a longer length than discontinuous fibers. Discontinuous fibers can be short fibers, which may be (e.g., cut from filaments) or formed as discontinuous discrete fibers to have a specific length or length range as described in more detail herein. In some embodiments, the nonwoven fiber web comprises continuous fibers with an average length greater than 5 inches.

[0164] When present, synthetic fibers can have a variety of suitable average lengths. In some embodiments, the nonwoven fiber web comprises synthetic fibers having the following average lengths: greater than or equal to 0.01 inches, greater than or equal to 0.02 inches, greater than or equal to 0.05 inches, greater than or equal to 0.075 inches, greater than or equal to 0.1 inches, greater than or equal to 0.2 inches, greater than or equal to 0.5 inches, greater than or equal to 0.75 inches, greater than or equal to 1 inch, greater than or equal to 2 inches, greater than or equal to 5 inches, or greater than or equal to 7.5 inches. In some embodiments, the nonwoven fiber web comprises synthetic fibers having the following average lengths: less than or equal to 10 inches, less than or equal to 7.5 inches, less than or equal to 5 inches, less than or equal to 2 inches, less than or equal to 1 inch, less than or equal to 0.75 inches, less than or equal to 0.5 inches, less than or equal to 0.2 inches, less than or equal to 0.1 inches, less than or equal to 0.075 inches, less than or equal to 0.05 inches, or less than or equal to 0.02 inches. Combinations of the above ranges are also possible (e.g., greater than or equal to 0.01 inches and less than or equal to 10 inches). Other ranges are also possible.

[0165] When a nonwoven fiber web comprises two or more types of synthetic fibers, the various types of synthetic fibers may have an average length within one or more of the aforementioned ranges. Furthermore, in some embodiments, all synthetic fibers in the nonwoven fiber web simultaneously have an average length within one or more of the aforementioned ranges. Similarly, when the filter media comprises two or more nonwoven fiber webs, each nonwoven fiber web may independently contain synthetic fibers with an average length within one or more of the aforementioned ranges (independently of one or more types, or all types simultaneously).

[0166] In some embodiments, the nonwoven fiber web includes bonding fibers. The bonding fibers can constitute various suitable amounts in the nonwoven fiber web. In some embodiments, the bonding fibers constitute 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, 40% or more by weight, 50% or more by weight, 60% or more by weight, or 80% or more by weight of the fibers in the nonwoven fiber web. In some embodiments, the bonding fiber constitutes less than or equal to 90% by weight, less than or equal to 80% 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 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 90% by weight, or greater than 0% by weight and less than or equal to 90% by weight). Other ranges are also possible. In some embodiments, the bonding fiber constitutes exactly 0% by weight of the fibers in the nonwoven fiber web.

[0167] Various suitable types of bonding fibers can be used in the nonwoven fiber webs described herein. In some embodiments, the bonding fibers comprise multicomponent fibers and / or monocomponent fibers. Multicomponent fibers may include bicomponent fibers (i.e., fibers comprising two components) and / or fibers comprising three or more components. Multicomponent fibers can have various suitable structures. For example, the nonwoven fiber web may comprise one or more of the following types of multicomponent 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-type" fibers. Core-sheath bicomponent fibers may comprise a sheath having a melting temperature lower than that of the core. When heated (e.g., during the bonding step), the sheath may melt before the core, thereby bonding the nonwoven fiber web together while the core remains solid.

[0168] Non-limiting examples of suitable materials that can be included in multicomponent and single-component adhesive fibers include: poly(olefins), such as poly(ethylene), poly(propylene), and poly(butene); poly(esters) and copoly(esters), such as polyethylene terephthalate (e.g., amorphous polyethylene 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 ether diols and aromatic / aliphatic ether diols having 4 to 10 carbon atoms (e.g., hydroquinone bis(2-hydroxyethyl) ethers and poly(vinyl ether) diols, such as diethylene glycol, with a molecular weight of less than 460 g / mol).

[0169] 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.

[0170] In embodiments where the nonwoven fiber web comprises two or more types of bicomponent fibers, each type of bicomponent fiber may independently comprise one of the aforementioned material pairs. According to some embodiments, the nonwoven fiber web may have a relatively low percentage of bicomponent fibers (e.g., fibers in the nonwoven fiber web less than or equal to 3% by weight, less than or equal to 2% by weight, less than or equal to 1% by weight, less than or equal to 0.5% by weight, less than or equal to 0.1% by weight, or 0%). In some embodiments, the nonwoven fiber web may be substantially free of bicomponent fibers. In some embodiments, the nonwoven fiber web contains no bicomponent fibers.

[0171] The single-component and multi-component adhesive fibers described herein may have various suitable melting points and / or contain components having various suitable melting points. In some embodiments, the nonwoven fiber web comprises single-component adhesive fibers having the following melting points and / or multi-component fibers containing components having the following 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 nonwoven fiber web comprises single-component bonded fibers having the following melting points and / or multi-component fibers containing components having the following melting points: less than or equal to 230°C, less than or equal to 220°C, less than or equal to 210°C, less than or equal to 200°C, less than or equal to 190°C, less than or equal to 180°C, less than or equal to 170°C, less than or equal to 160°C, less than or equal to 150°C, less than or equal to 140°C, less than or equal to 130°C, less than or equal to 120°C, less than or equal to 110°C, less than or equal to 100°C, or less than or equal to 90°C. Combinations of the above ranges are also possible (e.g., greater than or equal to 80°C and less than or equal to 230°C, or greater than or equal to 110°C and less than or equal to 230°C). Other ranges are also possible.

[0172] The melting point of a single-component fiber and the melting points of the components of a multi-component fiber can be determined by differential scanning calorimetry (DSC). DSC measurement is performed by heating the multi-component fiber to 300°C at 20°C / min, cooling it to room temperature, and then reheating it to 300°C at 20°C / min to determine the melting point.

[0173] When present, the bonding fibers can have a variety of suitable average diameters. In some embodiments, the nonwoven fiber web comprises bonding fibers having the following average diameters: 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 2 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 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, or greater than or equal to 45 micrometers. In some embodiments, the nonwoven fiber web comprises bonding fibers having the following average diameters: 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 7.5 micrometers, less than or equal to 5 micrometers, less than or equal to 2 micrometers, less than or equal to 1 micrometer, or less than or equal to 0.75 micrometers. Combinations of the above ranges are also possible (e.g., greater than or equal to 0.5 micrometers and less than or equal to 50 micrometers, greater than or equal to 1 micrometer and less than or equal to 50 micrometers, or greater than or equal to 2 micrometers and less than or equal to 50 micrometers). Other ranges are also possible.

[0174] When a nonwoven fiber web comprises two or more types of bonding fibers, the various types of bonding fibers may have an average diameter within one or more of the aforementioned ranges. Furthermore, in some embodiments, all bonding fibers in the nonwoven fiber web simultaneously have an average diameter within one or more of the aforementioned ranges. Similarly, when the filter medium comprises two or more nonwoven fiber webs, each nonwoven fiber web may independently contain bonding fibers with an average diameter within one or more of the aforementioned ranges (independently of one or more types, or all types simultaneously).

[0175] When present, the bonding fibers can have a variety of suitable average lengths. In some embodiments, the nonwoven fiber web comprises bonding fibers having the following average lengths: greater than or equal to 0.01 inches, greater than or equal to 0.02 inches, greater than or equal to 0.05 inches, greater than or equal to 0.075 inches, greater than or equal to 0.1 inches, greater than or equal to 0.2 inches, greater than or equal to 0.5 inches, greater than or equal to 0.75 inches, greater than or equal to 1 inch, greater than or equal to 1.25 inches, greater than or equal to 1.5 inches, greater than or equal to 2 inches, greater than or equal to 2.5 inches, greater than or equal to 3 inches, greater than or equal to 3.5 inches, greater than or equal to 4 inches, greater than or equal to 5 inches, greater than or equal to 6 inches, or greater than or equal to 8 inches. In some embodiments, the nonwoven fiber web comprises bonding fibers having the following average lengths: less than or equal to 10 inches, less than or equal to 8 inches, less than or equal to 6 inches, less than or equal to 5 inches, less than or equal to 4 inches, less than or equal to 3.5 inches, less than or equal to 3 inches, less than or equal to 2.5 inches, less than or equal to 2 inches, less than or equal to 2.5 inches, less than or equal to 2 inches, less than or equal to 1.5 inches, less than or equal to 1.25 inches, less than or equal to 1 inch, less than or equal to 0.75 inches, less than or equal to 0.5 inches, less than or equal to 0.2 inches, less than or equal to 0.1 inches, less than or equal to 0.075 inches, less than or equal to 0.05 inches, or less than or equal to 0.02 inches. Combinations of the above ranges are also possible (e.g., greater than or equal to 0.01 inches and less than or equal to 10 inches, greater than or equal to 0.01 inches and less than or equal to 5 inches, or greater than or equal to 0.05 inches and less than or equal to 3 inches). Other ranges are also possible.

[0176] When a nonwoven fiber web comprises two or more types of bonding fibers, each type of bonding fiber may have an average length within one or more of the aforementioned ranges. Furthermore, in some embodiments, all bonding fibers in the nonwoven fiber web simultaneously have an average length within one or more of the aforementioned ranges. Similarly, when the filter media comprises two or more nonwoven fiber webs, each nonwoven fiber web may independently contain bonding fibers with an average length within one or more of the aforementioned ranges (independently of one or more types, or all types simultaneously).

[0177] In some embodiments, the nonwoven fiber web comprises fibrillated fibers. The fibrillated fibers can include natural and / or synthetic fibers as described elsewhere herein. As a non-limiting example, the fibrillated fibers can include lyocell fibers. The fibrillated fibers can include parent fibers branching into fibrils of smaller diameter, which in some cases may further branch into even smaller diameter fibrils, where further branching is also possible. The branching nature of the fibrils can increase the surface area of ​​the fiber web employing fibrillated fibers and can increase the number of contact points between the fibrillated fibers and other fibers in the nonwoven fiber web. This increase in contact points between the fibrillated fibers and other fibers in the nonwoven fiber web can improve the mechanical properties (e.g., flexibility, strength) of the nonwoven fiber web.

[0178] When present, fibrillated fibers may contain stems with an average diameter within one or more of the range described elsewhere in this document for the average diameter of the relevant type of fiber (e.g., fibrillated synthetic fibers may contain stems with an average diameter within one or more of the range described elsewhere in this document for the average diameter of synthetic fibers, and fibrillated natural fibers may contain stems with an average diameter within one or more of the range described elsewhere in this document for the average diameter of natural fibers).

[0179] When present, fibrillated fibers (e.g., lyocell fibers) can comprise fibrils with various suitable diameters. In some embodiments, the nonwoven fiber web comprises fibrillated fibers containing fibrils with the following average diameters: 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 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, or greater than or equal to 1.75 micrometers. In some embodiments, the nonwoven fiber web comprises fibrillated fibers containing fibrils with the following average diameters: less than or equal to 2 micrometers, less than or equal to 1.75 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, or less than or equal to 0.2 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 2 micrometers). Other ranges are also possible.

[0180] When a nonwoven fiber web comprises two or more types of fibrillated fibers, each type of fibrillated fiber may contain fibrils with an average diameter within one or more of the aforementioned ranges. Furthermore, in some embodiments, the fibrils of all fibrillated fibers in the nonwoven fiber web simultaneously have an average diameter within one or more of the aforementioned ranges. Similarly, when a filter medium comprises two or more nonwoven fiber webs, each nonwoven fiber web may independently contain fibrillated fibers containing fibrils with an average diameter within one or more of the aforementioned ranges (independently of one or more types, or all types simultaneously).

[0181] When present, fibrillated fibers (e.g., lyocell fibers) can have a variety of suitable average lengths. In some embodiments, the average length of the fibrillated fibers is greater than or equal to 0.01 inches, greater than or equal to 0.03 inches, greater than or equal to 0.05 inches, greater than or equal to 0.1 inches, greater than or equal to 0.2 inches, greater than or equal to 0.3 inches, greater than or equal to 0.4 inches, greater than or equal to 0.5 inches, greater than or equal to 0.6 inches, greater than or equal to 0.7 inches, greater than or equal to 0.8 inches, or greater than or equal to 0.9 inches. In some implementations, the average length of the fibrillated fibers is less than or equal to 1 inch, less than or equal to 0.9 inches, less than or equal to 0.8 inches, less than or equal to 0.7 inches, less than or equal to 0.6 inches, less than or equal to 0.5 inches, less than or equal to 0.4 inches, less than or equal to 0.3 inches, less than or equal to 0.2 inches, less than or equal to 0.1 inches, less than or equal to 0.05 inches, less than or equal to 0.03 inches, or less than or equal to 0.02 inches. Combinations of the above ranges are also possible (e.g., greater than or equal to 0.01 inches and less than or equal to 1 inch, greater than or equal to 0.1 inches and less than or equal to 0.5 inches, or greater than or equal to 0.1 inches and less than or equal to 0.3 inches). Other ranges are also possible.

[0182] When a nonwoven fiber web comprises two or more types of fibrillated fibers, each type of fibrillated fiber may independently have an average fiber length within one or more of the aforementioned ranges, and / or all fibrillated fibers in the nonwoven fiber web may simultaneously have an average fiber length within one or more of the aforementioned ranges. Similarly, when a filter medium comprises two or more nonwoven fiber webs, each nonwoven fiber web may independently contain one or more types of fibrillated fibers with an average fiber length within one or more of the aforementioned ranges, and / or may contain fibrillated fibers with an overall average fiber length within one or more of the aforementioned ranges.

[0183] When present, fibrillated fibers (e.g., lyocell fibers) can be present in the nonwoven fiber web in various suitable amounts. In some embodiments, fibrillated fibers can be present in the nonwoven fiber web in the following amounts: greater than 0 wt%, greater than or equal to 0.01 wt%, greater than or equal to 0.02 wt%, greater than or equal to 0.03 wt%, greater than or equal to 0.05 wt%, greater than or equal to 0.08 wt%, greater than or equal to 0.1 wt%, greater than or equal to 0.2 wt%, greater than or equal to 0.3 wt%, greater than or equal to 0.5 wt%, greater than or equal to 0.8 wt%, greater than or equal to 1 wt%, greater than or equal to 1.5 wt%, greater than or equal to 2 wt%, greater than or equal to 3 wt%, greater than or equal to 4 wt%, greater than or equal to 5 wt%, greater than or equal to 8 wt%, greater than or equal to 10 wt%, greater than or equal to 12 wt%, greater than or equal to 15 wt%, or greater than or equal to 18 wt%. According to some implementation schemes, fibrillated fibers may be present in the nonwoven fiber web in the following amounts: less than or equal to 20% by weight, less than or equal to 18% by weight, less than or equal to 15% by weight, less than or equal to 12% by weight, less than or equal to 10% by weight, less than or equal to 8% 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% by weight, less than or equal to 1.5% by weight, less than or equal to 1% by weight, less than or equal to 0.8% by weight, less than or equal to 0.5% by weight, less than or equal to 0.3% by weight, less than or equal to 0.2% by weight, less than or equal to 0.1% by weight, less than or equal to 0.08% by weight, less than or equal to 0.05% by weight, less than or equal to 0.03% by weight, less than or equal to 0.02% by weight, or less than or equal to 0.01% by weight. Combinations of the aforementioned ranges are possible (e.g., greater than or equal to 0% by weight and less than or equal to 20% by weight of nonwoven fiber webs, greater than 0% by weight and less than or equal to 20% by weight of nonwoven fiber webs, greater than 0% by weight and less than or equal to 15% by weight of nonwoven fiber webs, greater than 0% by weight and less than or equal to 12% by weight of nonwoven fiber webs, greater than 0% by weight and less than or equal to 10% by weight of nonwoven fiber webs, greater than 0% by weight and less than or equal to 5% by weight of nonwoven fiber webs, greater than 0% by weight and less than or equal to 2% by weight of nonwoven fiber webs, or greater than 0% by weight and less than or equal to 1% by weight of nonwoven fiber webs). Other ranges are also possible.

[0184] When a nonwoven fiber web comprises two or more types of fibrillated fibers, each type of fibrillated fiber may independently constitute one or more of the amounts within the aforementioned range of the nonwoven fiber web. Furthermore, in some embodiments, the total amount of fibrillated fibers in the nonwoven fiber web may be within one or more of the aforementioned range. Similarly, when a filter medium comprises two or more nonwoven fiber webs, each type of fibrillated fiber may independently constitute one or more of the amounts within the aforementioned range of each nonwoven fiber web, and / or the total amount of fibrillated fibers in each nonwoven fiber web may independently be within one or more of the aforementioned range.

[0185] In some embodiments, if the amount of fibrillated fibers (e.g., lyocell fibers) in the nonwoven fiber web is too high, the nonwoven fiber web may have relatively high flammability and / or relatively low properties (e.g., relatively low gamma). In some embodiments, if the amount of fibrillated fibers (e.g., lyocell fibers) in the nonwoven fiber web is too low, the nonwoven fiber web may have relatively low strength (e.g., wet strength), relatively low flexibility, and / or relatively low processability. Therefore, in some embodiments, a nonwoven fiber web containing an amount of fibrillated fibers (e.g., lyocell fibers) within the above-described range has reduced flammability, increased strength (e.g., wet strength), increased flexibility, increased processability, and / or improved properties (e.g., increased gamma) compared to a nonwoven fiber web with all other factors being equal except for the amount of fibrillated fibers (e.g., lyocell fibers) outside the above-described range. In some embodiments, the use of fibrillated fibers (e.g., lyocell fibers) within the above-described range provides sufficient flame retardant properties, strength (e.g., wet strength), flexibility, processability, and / or performance (e.g., γ) such that a small amount (e.g., the amount disclosed herein) or no additional synthetic fibers (e.g., bicomponent fibers and / or synthetic fibers containing poly(vinyl alcohol)) is required to achieve the desired flame retardant properties, strength (e.g., wet strength), flexibility, processability, and / or performance (e.g., γ).

[0186] When a nonwoven fiber web comprises two or more types of fibrillated fibers, each type of fibrillated fiber may contain fibrils with an average diameter within one or more of the aforementioned ranges. Furthermore, in some embodiments, the fibrils of all fibrillated fibers in the nonwoven fiber web simultaneously have an average diameter within one or more of the aforementioned ranges. Similarly, when the filter media comprises two or more nonwoven fiber webs, each nonwoven fiber web may independently contain fibrillated fibers (independently one or more types, or all types together) containing fibrils with an average diameter within one or more of the aforementioned ranges.

[0187] When present, fibrillated fibers can have a variety of suitable fibrillation levels. In some embodiments, the nonwoven fiber web comprises fibrillated fibers with the following fibrillation levels: greater than or equal to 1 CSF, greater than or equal to 2 CSF, greater than or equal to 3 CSF, greater than or equal to 4 CSF, greater than or equal to 5 CSF, greater than or equal to 7.5 CSF, greater than or equal to 10 CSF, greater than or equal to 20 CSF, greater than or equal to 50 CSF, greater than or equal to 75 CSF, greater than or equal to 100 CSF, greater than or equal to 200 CSF, greater than or equal to 225 CSF, greater than or equal to 240 CSF, greater than or equal to 300 CSF, greater than or equal to 350 CSF, greater than or equal to 400 CSF, greater than or equal to 500 CSF, greater than or equal to 750 CSF, or greater than or equal to 900 CSF. In some embodiments, the nonwoven fiber web comprises fibrillated fibers having fibrillation levels of: less than or equal to 1000 CSF, less than or equal to 900 CSF, less than or equal to 750 CSF, less than or equal to 600 CSF, less than or equal to 550 CSF, less than or equal to 500 CSF, less than or equal to 450 CSF, less than or equal to 400 CSF, less than or equal to 350 CSF, less than or equal to 240 CSF, less than or equal to 200 CSF, less than or equal to 100 CSF, less than or equal to 75 CSF, less than or equal to 50 CSF, less than or equal to 20 CSF, less than or equal to 10 CSF, less than or equal to 7.5 CSF, less than or equal to 5 CSF, less than or equal to 4 CSF, less than or equal to 3 CSF, or less than or equal to 2 CSF. Combinations of the above ranges are also possible (e.g., greater than or equal to 1 CSF and less than or equal to 1000 CSF, greater than or equal to 3 CSF and less than or equal to 1000 CSF, or greater than or equal to 5 CSF and less than or equal to 900 CSF, greater than or equal to 10 CSF and less than or equal to 600 CSF, greater than or equal to 200 CSF and less than or equal to 500 CSF, or greater than or equal to 240 CSF and less than or equal to 400 CSF). Other ranges are also possible.

[0188] The fibrillation of fibrillated fibers can be measured according to the Canadian Standard Freeness Test, which is specified by TAPPI Test Method T-227-om-09 Freeness of Pulp (2009). This test can provide an average CSF value.

[0189] When a nonwoven fiber web comprises two or more types of fibrillated fibers, each type of fibrillated fiber may have a fibrillation level within one or more of the aforementioned ranges. Furthermore, in some embodiments, all fibrillated fibers in the nonwoven fiber web simultaneously have fibrillation levels within one or more of the aforementioned ranges. Similarly, when a filter medium comprises two or more nonwoven fiber webs, each nonwoven fiber web may independently contain fibrillated fibers with fibrillation levels within one or more of the aforementioned ranges (independently one or more types, or all types simultaneously).

[0190] In some embodiments, nonwoven fiber webs containing fibrillated fibers (e.g., lyocell fibers) within the aforementioned range have improved performance (e.g., γ) compared to nonwoven fiber webs containing fibrillated fibers (e.g., lyocell fibers) with all other factors being the same but outside the aforementioned range.

[0191] In some embodiments, the filter media (e.g., containing one or more of the water-repellent additives, resins, and / or fibers described above) does not contain certain fluorinated materials regulated by government agencies. For example, in some embodiments, the filter media does not contain perfluoroalkyl substances, polyfluoroalkyl substances, and / or fluorotelomers. As another example, in some embodiments, the filter media does not contain perfluoroalkyl sulfonic acids (e.g., perfluoroalkyl sulfonic acids containing carbon chains of six or more carbon atoms, such as perfluorohexane sulfonic acid and / or perfluorooctane sulfonic acid), perfluorocarboxylic acids (e.g., perfluorocarboxylic acids containing carbon chains of eight or more carbon atoms, such as perfluorooctanoic acid), perfluoroalkyl substances containing carbon chains of five or fewer carbon atoms (e.g., perfluorobutane sulfonic acid), perfluoroalkyl substances containing carbon chains of seven or fewer carbon atoms (e.g., perfluorohexanoic acid), and / or precursors capable of degradation to form any of the aforementioned substances (e.g., feedstocks based on long-chain perfluoroalkyl sulfonyl fluorides, fluorotelomers).

[0192] In some embodiments, the filter media (e.g., comprising one or more of the types of water-repellent additives, resins, and / or fibers described above) contains relatively small amounts of one or more fluorinated materials regulated by government agencies (e.g., one or more fluorinated materials described in the preceding paragraphs). The relevant fluorinated material may constitute 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, less than or equal to 1% by weight, less than or equal to 0.1% by weight, or less than or equal to 0.01% by weight of the non-fibrous component of the filter media. The relevant fluorinated material may constitute greater than or equal to 0% by weight, greater than 0% by weight, greater than or equal to 0.01% by weight, greater than or equal to 0.1% 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 7.5% by weight, or greater than or equal to 10% by weight of the non-fibrous component of the filter media. Combinations of the above ranges are also possible (e.g., less than or equal to 15% by weight and greater than or equal to 0% by weight, or less than or equal to 15% by weight and greater than 0% by weight). In some embodiments, one or more fluorinated materials regulated by government agencies similarly constitute 0% by weight of the non-fibrous components in the filter media.

[0193] The nonwoven fiber webs described in this article can have various suitable weights per unit area. In some implementations, the nonwoven fiber web has an area weight greater than or equal to 20 gsm, 30 gsm, 40 gsm, 50 gsm, 60 gsm, 70 gsm, 80 gsm, 90 gsm, 100 gsm, 110 gsm, 120 gsm, 130 gsm, 140 gsm, 150 gsm, 160 gsm, 170 gsm, 180 gsm, 190 gsm, 200 gsm, 225 gsm, 250 gsm, 275 gsm, 300 gsm, or 350 gsm. gsm, greater than or equal to 400 gsm, or greater than or equal to 450 gsm. In some implementations, the area weight of the nonwoven fiber web 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 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 190 gsm, less than or equal to 180 gsm, less than or equal to 170 gsm, less than or equal to 160 gsm, less than or equal to 150 gsm, less than or equal to 140 gsm, less than or equal to 130 gsm, less than or equal to 120 gsm, less than or equal to 110 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 5 ... The ranges are gsm, less than or equal to 40 gsm, or less than or equal to 30 gsm. Combinations of these ranges are also possible (e.g., greater than or equal to 20 gsm and less than or equal to 500 gsm, greater than or equal to 20 gsm and less than or equal to 400 gsm, greater than or equal to 20 gsm and less than or equal to 200 gsm, greater than or equal to 20 gsm and less than or equal to 150 gsm, greater than or equal to 20 gsm and less than or equal to 130 gsm, greater than or equal to 30 gsm and less than or equal to 400 gsm, or greater than or equal to 40 gsm and less than or equal to 250 gsm). Other ranges are also possible.

[0194] The weight per unit area of ​​nonwoven fiber webs can be determined according to ISO 536:2012.

[0195] When the filter medium comprises two or more nonwoven fiber webs, each nonwoven fiber web may independently have a unit area weight within one or more of the above ranges.

[0196] The nonwoven fiber web described herein can have various suitable thicknesses. In some embodiments, the thickness of the nonwoven fiber web is greater than or equal to 100 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 400 micrometers, greater than or equal to 500 micrometers, greater than or equal to 750 micrometers, greater than or equal to 1000 micrometers, greater than or equal to 2000 micrometers, greater than or equal to 3000 micrometers, or greater than or equal to 4000 micrometers. In some embodiments, the thickness of the nonwoven fiber web is less than or equal to 5000 micrometers, less than or equal to 4000 micrometers, less than or equal to 3000 micrometers, less than or equal to 200 micrometers, less than or equal to 1000 micrometers, less than or equal to 750 micrometers, less than or equal to 500 micrometers, less than or equal to 400 micrometers, less than or equal to 300 micrometers, less than or equal to 200 micrometers, or less than or equal to 200 micrometers. Combinations of the above ranges are also possible (e.g., greater than or equal to 100 micrometers and less than or equal to 5000 micrometers, greater than or equal to 200 micrometers and less than or equal to 5000 micrometers, greater than or equal to 200 micrometers and less than or equal to 3000 micrometers, or greater than or equal to 250 micrometers and less than or equal to 2000 micrometers). Other ranges are also possible.

[0197] The thickness of the nonwoven fiber web can be determined according to ASTM D1777-96 (2019) under an applied pressure of 2 kPa.

[0198] When the filter medium comprises two or more nonwoven fiber webs, each nonwoven fiber web may independently have a thickness within one or more of the above ranges.

[0199] The nonwoven fiber web described herein can have a variety of suitable average flow apertures. In some embodiments, the average flow aperture of the nonwoven fiber web is 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 1.75 micrometers, greater than or equal to 2 micrometers, greater than or equal to 2.25 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 17.5 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 flow aperture of the nonwoven fiber web is 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 17.5 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, 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 2.25 micrometers, less than or equal to 2 micrometers, less than or equal to 1.75 micrometers, less than or equal to 1.5 micrometers, less than or equal to 1.25 micrometers, less than or equal to 1 micrometer, or less than or equal to 0.75 micrometers. Combinations of the above ranges are also possible (e.g., greater than or equal to 0.5 micrometers and less than or equal to 50 micrometers, greater than or equal to 0.5 micrometers and less than or equal to 30 micrometers, or greater than or equal to 1 micrometer and less than or equal to 15 micrometers). Other ranges are also possible.

[0200] The average flow aperture of a nonwoven fiber web can be determined according to ASTM F316-90 Method B (2019).

[0201] When the filter medium comprises two or more nonwoven fiber webs, each nonwoven fiber web may independently have an average flow aperture within one or more of the above ranges.

[0202] The nonwoven fiber webs described herein can have a variety of suitable maximum pore sizes. In some embodiments, the maximum pore size of the nonwoven fiber web is greater than or equal to 1.5 micrometers, greater than or equal to 1.75 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 6 micrometers, greater than or equal to 8 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 17.5 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 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 embodiments, the maximum aperture of the nonwoven fiber web 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 17.5 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 8 micrometers, less than or equal to 6 micrometers, 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, or less than or equal to 1.75 micrometers. Combinations of the above ranges are also possible (e.g., greater than or equal to 1.5 micrometers and less than or equal to 100 micrometers, greater than or equal to 1.5 micrometers and less than or equal to 50 micrometers, or greater than or equal to 2.5 micrometers and less than or equal to 40 micrometers). Other ranges are also possible.

[0203] The maximum aperture of a nonwoven fiber web can be determined according to ASTM F316-90 Method B (2019).

[0204] When the filter medium comprises two or more nonwoven fiber webs, each nonwoven fiber web may independently have a maximum pore size within one or more of the above ranges.

[0205] The nonwoven fiber webs and / or filter media described herein can have various suitable water roll-off angles. In some embodiments, the water roll-off angle of the nonwoven fiber webs and / or filter media is greater than or equal to 0.5 degrees, greater than or equal to 1 degree, greater than or equal to 2 degrees, greater than or equal to 3 degrees, greater than or equal to 4 degrees, greater than or equal to 5 degrees, greater than or equal to 7 degrees, greater than or equal to 10 degrees, greater than or equal to 12 degrees, greater than or equal to 15 degrees, greater than or equal to 20 degrees, greater than or equal to 25 degrees, greater than or equal to 30 degrees, greater than or equal to 35 degrees, or greater than or equal to 40 degrees. In some embodiments, the water roll-off angle of the nonwoven fiber web and / or filter media is less than or equal to 45 degrees, less than or equal to 43 degrees, less than or equal to 40 degrees, less than or equal to 38 degrees, less than or equal to 35 degrees, less than or equal to 33 degrees, less than or equal to 30 degrees, less than or equal to 28 degrees, less than or equal to 25 degrees, less than or equal to 23 degrees, less than or equal to 20 degrees, less than or equal to 18 degrees, less than or equal to 15 degrees, less than or equal to 13 degrees, less than or equal to 10 degrees, less than or equal to 8 degrees, or less than or equal to 5 degrees. Combinations of the above ranges are also possible (e.g., greater than or equal to 0.5 degrees and less than or equal to 45 degrees, greater than or equal to 0.5 degrees and less than or equal to 25 degrees, or greater than or equal to 0.5 degrees and less than or equal to 15 degrees). Other ranges are also possible.

[0206] The water roll-off angle of the nonwoven fiber web and / or filter media is an angle relative to the horizontal plane. At or above this angle, water droplets (approximately 5 μl in volume) placed on the surface of the nonwoven fiber web and / or filter media at 22°C will not remain stationary but will roll to the edge or leave the surface.

[0207] When the filter media comprises two or more nonwoven fiber webs, each nonwoven fiber web may independently have a water roll-off angle within one or more of the above ranges.

[0208] In some embodiments, the nonwoven fiber web and / or filter media are relatively flexible. For example, in some embodiments, the AC Flex Light Weight of the nonwoven fiber web and / or filter media is greater than or equal to 1 cycle, greater than or equal to 2 cycles, greater than or equal to 3 cycles, greater than or equal to 4 cycles, greater than or equal to 5 cycles, greater than or equal to 10 cycles, greater than or equal to 15 cycles, greater than or equal to 20 cycles, greater than or equal to 25 cycles, greater than or equal to 30 cycles, greater than or equal to 35 cycles, greater than or equal to 40 cycles, greater than or equal to 45 cycles, greater than or equal to 50 cycles, greater than or equal to 55 cycles, greater than or equal to 60 cycles, greater than or equal to 75 cycles, greater than or equal to 100 cycles, greater than or equal to 125 cycles, greater than or equal to 150 cycles, greater than or equal to 175 cycles, greater than or equal to 200 cycles, greater than or equal to 250 cycles, greater than or equal to 300 cycles, or greater than or equal to 350 cycles. In some implementations, the AC Flex Light Weight of the nonwoven fiber web and / or filter media is less than or equal to 400 cycles, less than or equal to 375 cycles, less than or equal to 350 cycles, less than or equal to 325 cycles, less than or equal to 300 cycles, less than or equal to 275 cycles, less than or equal to 250 cycles, less than or equal to 225 cycles, less than or equal to 200 cycles, less than or equal to 175 cycles, less than or equal to 150 cycles, less than or equal to 125 cycles, less than or equal to 100 cycles, less than or equal to 90 cycles, less than or equal to 80 cycles, less than or equal to 75 cycles, less than or equal to 70 cycles, and so on. The possible ranges are 68 or more cycles, 65 or less cycles, 63 or less cycles, 60 or less cycles, 58 or less cycles, 55 or less cycles, 53 or less cycles, 50 or less cycles, 48 ​​or less cycles, 45 or less cycles, 43 or less cycles, 40 or less cycles, 35 or less cycles, 30 or less cycles, 25 or less cycles, 20 or less cycles, 15 or less cycles, 10 or less cycles, and 5 or less cycles. Combinations of these ranges are also possible (e.g., 1 or more cycles and 400 or less cycles, 1 or more cycles and 100 or less cycles, 1 or more cycles and 70 or less cycles, 10 or more cycles and 70 or less cycles, or 30 or more cycles and 70 or less cycles). Other ranges are also possible.AC Flex Light Weight (AC Flex Lt Wt) can be measured using an AC Flex tester on a 2-inch × 4-inch cut sample, with the 4-inch side aligned with the machine orientation. The sample is clamped in the sample holder. The tester is activated to flex the sample at a rate of 48 cycles per minute (+ / - 1 cycle) using a flex weight of 413.2 grams. The number of flex cycles until the sample breaks is recorded. When the filter media comprises two or more nonwoven fiber webs, each nonwoven fiber web can independently have an AC Flex Light Weight within one of the above ranges.

[0209] In some embodiments, the filter media and / or nonwoven fiber web are relatively fire-resistant. For example, in some embodiments, the filter media and / or nonwoven fiber web have an F1 and / or K1 rating as measured according to DIN 53438 (June 1984). When the filter media comprises two or more nonwoven fiber webs, each nonwoven fiber web may independently have an F1 and / or K1 rating as measured according to DIN 53438 (June 1984).

[0210] According to some embodiments, the nonwoven fiber web possesses sufficient wet strength to facilitate its processing. For example, in some embodiments, the nonwoven fiber web has sufficient wet strength such that it can be processed during manufacturing without breaking, tearing, or otherwise degrading. In some embodiments, it may be desirable to include certain components described herein in the filter medium to improve the wet strength of the nonwoven fiber web. For example, in some embodiments, the inclusion of fibrillated fibers (e.g., lyocell fibers) in the nonwoven fiber medium can improve the wet strength of the nonwoven fiber web. According to some embodiments, other components described herein can also improve the wet strength of the nonwoven fiber web.

[0211] The wet strength of one or more nonwoven fiber webs can be a variety of suitable values. Thus, in some embodiments, the wet strength of the nonwoven fiber web is greater than or equal to 5 g, greater than or equal to 10 g, greater than or equal to 20 g, greater than or equal to 30 g, greater than or equal to 40 g, greater than or equal to 50 g, greater than or equal to 60 g, greater than or equal to 70 g, greater than or equal to 80 g, or greater than or equal to 90 g. In some embodiments, the wet strength of the nonwoven fiber web is less than or equal to 100 g, less than or equal to 90 g, less than or equal to 80 g, less than or equal to 70 g, less than or equal to 60 g, less than or equal to 50 g, less than or equal to 40 g, less than or equal to 30 g, less than or equal to 20 g, or less than or equal to 10 g. Combinations of the foregoing ranges are possible (e.g., greater than or equal to 5 g and less than or equal to 100 g, or greater than or equal to 40 g and less than or equal to 80 g). Other ranges are also possible.

[0212] Wet strength can be determined as follows. Methods such as... Figures 2A to 2C The system 205 in the system. A 2” × 4.5” sample (e.g., sample 215) is cut from the middle of the wet nonwoven fiber web. The wet sample (e.g., sample 215) is positioned in the system (e.g., as shown in the figure). Figures 2A to 2C In the system 205 shown, a metal block (e.g., metal block 210) is placed on top of the wet sample (e.g., sample 215) to hold it in place, balanced by a counterweight below, so that there is no tensile stress on the sample (e.g., sample 215). A measuring cylinder (e.g., measuring cylinder 220) is filled with water, and a water valve is opened to allow water to flow from the measuring cylinder into a pan (e.g., pan 230). The weight of the water in the pan (e.g., pan 230) is applied as tensile stress to the wet sample (e.g., sample 215). The method continues until enough water is added to the pan (e.g., pan 230) to pull the wet sample (e.g., sample 215) apart. Figure 2C (As shown in the diagram). The weight (in grams) of water sufficient to pull apart a wet sample is the wet strength of the nonwoven fiber web.

[0213] The nonwoven fiber webs described herein can have a variety of suitable air resistances. In some embodiments, the air resistance of the nonwoven fiber web is greater than or equal to 0.5 Pa, greater than or equal to 0.6 Pa, greater than or equal to 0.8 Pa, greater than or equal to 1 Pa, greater than or equal to 2 Pa, greater than or equal to 5 Pa, greater than or equal to 7.5 Pa, greater than or equal to 10 Pa, greater than or equal to 20 Pa, greater than or equal to 25 Pa, greater than or equal to 28 Pa, greater than or equal to 30 Pa, greater than or equal to 35 Pa, greater than or equal to 40 Pa, greater than or equal to 45 Pa, greater than or equal to 50 Pa, greater than or equal to 55 Pa, greater than or equal to 60 Pa, greater than or equal to 75 Pa, greater than or equal to 100 Pa, greater than or equal to 200 Pa, greater than or equal to 300 Pa, greater than or equal to 400 Pa, greater than or equal to 500 Pa, greater than or equal to 600 Pa, or greater than or equal to 700 Pa. In some implementations, the air resistance of the nonwoven fiber web is less than or equal to 800 Pa, less than or equal to 700 Pa, less than or equal to 600 Pa, less than or equal to 500 Pa, less than or equal to 400 Pa, less than or equal to 300 Pa, less than or equal to 200 Pa, less than or equal to 100 Pa, less than or equal to 75 Pa, less than or equal to 60 Pa, less than or equal to 55 Pa, less than or equal to 50 Pa, less than or equal to 45 Pa, less than or equal to 40 Pa, less than or equal to 35 Pa, less than or equal to 30 Pa, less than or equal to 28 Pa, less than or equal to 25 Pa, less than or equal to 20 Pa, less than or equal to 10 Pa, less than or equal to 7.5 Pa, less than or equal to 5 Pa, less than or equal to 2 Pa, less than or equal to 1 Pa, less than or equal to 0.8 Pa, or less than or equal to 0.6 Pa. Combinations of the above ranges are also possible (e.g., greater than or equal to 0.5 Pa and less than or equal to 800 Pa, greater than or equal to 0.5 Pa and less than or equal to 60 Pa, greater than or equal to 0.8 Pa and less than or equal to 30 Pa, or greater than or equal to 2 Pa and less than or equal to 800 Pa). Other ranges are also possible.

[0214] The air resistance of a nonwoven fiber web can be determined by measuring the air permeability of the nonwoven fiber web in CFM (cfm / sf) using a Textest Instruments FX 3300 Air Permeability Tester III, and then dividing the measured air permeability by 113.5. Air permeability measurements can be performed according to ASTM D737-04 (2016) at a pressure of 125 Pa and a face velocity of 5.33 cm / s.

[0215] When the filter medium comprises two or more nonwoven fiber webs, each nonwoven fiber web can independently have air resistance within one or more of the above ranges.

[0216] In some embodiments, the nonwoven fiber web has a relatively high dry tensile strength in the machine direction. The tensile strength in the machine direction can be greater than or equal to 0.25 kN / m, greater than or equal to 0.5 kN / m, greater than or equal to 0.75 kN / m, greater than or equal to 1 kN / m, greater than or equal to 1.5 kN / m, greater than or equal to 2 kN / m, greater than or equal to 2.5 kN / m, greater than or equal to 3 kN / m, greater than or equal to 4 kN / m, greater than or equal to 5 kN / m, greater than or equal to 6 kN / m, greater than or equal to 7.5 kN / m, greater than or equal to 10 kN / m, or greater than or equal to 12.5 kN / m. The dry tensile strength in the machine direction can be less than or equal to 15 kN / m, less than or equal to 12.5 kN / m, less than or equal to 10 kN / m, less than or equal to 7.5 kN / m, less than or equal to 6 kN / m, less than or equal to 5 kN / m, less than or equal to 4 kN / m, less than or equal to 3 kN / m, less than or equal to 2.5 kN / m, less than or equal to 2 kN / m, less than or equal to 1.5 kN / m, less than or equal to 1 kN / m, less than or equal to 0.75 kN / m, or less than or equal to 0.5 kN / m. Combinations of the above ranges are also possible (e.g., greater than or equal to 0.25 kN / m and less than or equal to 15 kN / m). Other ranges are also possible.

[0217] The dry tensile strength of a nonwoven fiber web in the machine direction can be determined according to standard T494 om-96 (1996) using a test span of 5 inches and a gripper separation speed of 1 inch / minute.

[0218] When the filter medium comprises two or more nonwoven fiber webs, each nonwoven fiber web may independently have a dry tensile strength in the machine direction within one or more of the above ranges.

[0219] In some implementations, the nonwoven fiber web has a relatively high machine-direction Gurley stiffness. The machine-direction Gurley stiffness can be 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 600 mg, greater than or equal to 750 mg, greater than or equal to 1000 mg, greater than or equal to 1250 mg, greater than or equal to 1500 mg, greater than or equal to 2000 mg, greater than or equal to 2500 mg, greater than or equal to 3000 mg, greater than or equal to 3500 mg, greater than or equal to 4000 mg, or greater than or equal to 4500 mg. The Gurley stiffness in the machine direction can be less than or equal to 5000 mg, less than or equal to 4500 mg, less than or equal to 4000 mg, less than or equal to 3500 mg, less than or equal to 3000 mg, less than or equal to 2500 mg, less than or equal to 2000 mg, less than or equal to 1500 mg, less than or equal to 1250 mg, less than or equal to 1000 mg, less than or equal to 750 mg, less than or equal to 600 mg, less than or equal to 500 mg, or less than or equal to 400 mg. Combinations of the above ranges are also possible (e.g., greater than or equal to 300 mg and less than or equal to 5000 mg). Other ranges are also possible.

[0220] The Gurley stiffness of nonwoven fiber webs can be determined according to TAPPI T543 om-94 (1994).

[0221] The nonwoven fiber webs described herein can have various oil grades. In some embodiments, the oil grade of the nonwoven fiber web is greater than or equal to 0, greater than or equal to 1, greater than or equal to 2, greater than or equal to 3, greater than or equal to 4, or greater than or equal to 5. In some embodiments, the oil grade of the nonwoven fiber web is less than or equal to 6, less than or equal to 5, less than or equal to 4, less than or equal to 3, less than or equal to 2, or less than or equal to 1. Combinations of the above ranges are also possible (e.g., greater than or equal to 0 and less than or equal to 6, greater than or equal to 1 and less than or equal to 6, greater than or equal to 2 and less than or equal to 5, greater than or equal to 3 and less than or equal to 4, or greater than or equal to 5 and less than or equal to 6). Other ranges are also possible.

[0222] Oil grades can be determined according to AATCC TM 118 (2020) 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 nonwoven fabric. After 30 seconds of contact with the fabric at 23°C and 50% RH, the test oil with the highest surface tension that does not wet the surface of the nonwoven fabric (e.g., a contact angle greater than or equal to 90°) 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 nonwoven fabric after 30 seconds (i.e., a contact angle greater than or equal to 90°), but a test oil with a surface tension of 25.4 mN / m wets the surface of the nonwoven fabric within 30 seconds, then the oil grade of the nonwoven fabric 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 nonwoven web after 30 seconds, but a test oil with a surface tension of 23.8 mN / m wets the surface of the nonwoven web within 30 seconds, then the oil grade of the nonwoven 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 nonwoven web after 30 seconds, but a test oil with a surface tension of 21.6 mN / m wets the surface of the nonwoven web within 30 seconds, then the oil grade of the nonwoven 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 nonwoven fiber web after 30 seconds, but the test oil with a surface tension of 23.8 mN / m only partially wets the surface of the nonwoven 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 nonwoven fiber web), then the oil grade of the nanofiber layer is 5.5.

[0223] Table 1.

[0224]

[0225] When the filter media comprises two or more nonwoven fiber webs, each nonwoven fiber web may independently have an oil grade within one or more of the above ranges.

[0226] The nonwoven fiber webs described herein can have a relatively low poly(urethane) wicking height. During filter media manufacturing, poly(urethane) adhesives are commonly used to bond the nonwoven fiber webs together, to other components of the filter media (e.g., other layers therein), and / or to one or more components of the filter element in which the filter media is positioned (e.g., a frame). Therefore, a low poly(urethane) wicking height can be advantageous because it reduces the penetration of any poly(urethane) adhesive used into the nonwoven fiber web. This can advantageously allow the pores in the nonwoven fiber web and / or the surface of the nonwoven fiber web to remain relatively open and / or unclogging. It can also allow the adhesive to remain in its intended position, which can help maintain the intended adhesion and / or seal the filter media to its frame. In some embodiments, the poly(urethane) wicking height of the nonwoven fiber web is 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 22.5 mm, less than or equal to 20 mm, less than or equal to 17.5 mm, less than or equal to 15 mm, less than or equal to 12.5 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 2 mm, or less than or equal to 1 mm. In some embodiments, the poly(urethane) wicking height of the nonwoven fiber web is greater than or equal to 0 mm, greater than or equal to 1 mm, greater than or equal to 2 mm, greater than or equal to 5 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 17.5 mm, greater than or equal to 20 mm, greater than or equal to 22.5 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. Combinations of the above ranges are also possible (e.g., less than or equal to 50 mm and greater than or equal to 0 mm, less than or equal to 20 mm and greater than or equal to 0 mm, or less than or equal to 10 mm and greater than or equal to 0 mm). Other ranges are also possible.

[0227] The poly(urethane) wicking height of the nonwoven fiber web can be determined by the process described in embodiment 5.

[0228] When the filter media comprises two or more nonwoven fiber webs, each nonwoven fiber web may independently have a poly(urethane) wicking height within one or more of the above ranges.

[0229] The nonwoven fiber webs described herein can have a variety of suitable average oil carrying capacities. In some embodiments, the average oil carrying capacity of the nonwoven fiber web is less than or equal to 30 mg / m³. 3 Less than or equal to 27.5 mg / m 3 Less than or equal to 25 mg / m 3 Less than or equal to 22.5 mg / m 3 Less than or equal to 20 mg / m 3 Less than or equal to 17.5 mg / m 3 Less than or equal to 15 mg / m 3 Less than or equal to 12.5 mg / m³ 3 Less than or equal to 10 mg / m 3 Less than or equal to 7.5 mg / m 3 Less than or equal to 5 mg / m 3 Less than or equal to 2 mg / m 3 Less than or equal to 1 mg / m 3 Less than or equal to 0.75 mg / m 3 Less than or equal to 0.5 mg / m 3 Less than or equal to 0.2 mg / m 3 Less than or equal to 0.1 mg / m 3 Less than or equal to 0.075 mg / m 3 Less than or equal to 0.05 mg / m 3 Less than or equal to 0.02 mg / m 3 Less than or equal to 0.01 mg / m³ 3 Less than or equal to 0.0075 mg / m³ 3 Less than or equal to 0.005 mg / m 3 Less than or equal to 0.002 mg / m³ 3 Less than or equal to 0.001 mg / m³ 3 Less than or equal to 0.00075 mg / m 3 Less than or equal to 0.0005 mg / m 3 Less than or equal to 0.0002 mg / m³ 3 or less than or equal to 0.0001 mg / m 3 In some implementations, the average oil carryover of the nonwoven fiber web is greater than or equal to 0.00005 mg / m³. 3 ≥0.0001 mg / m 3 ≥0.0002 mg / m 3 ≥0.0005 mg / m 3≥0.00075 mg / m 3 ≥0.001 mg / m 3 ≥0.002 mg / m 3 ≥0.005mg / m 3 ≥0.0075 mg / m 3 ≥0.01 mg / m 3 ≥0.02 mg / m 3 ≥0.05 mg / m 3 ≥0.075 mg / m 3 ≥0.1 mg / m 3 ≥0.2 mg / m 3 ≥0.5 mg / m 3 ≥0.75 mg / m 3 ≥1 mg / m 3 ≥2 mg / m 3 ≥5 mg / m 3 ≥7.5 mg / m 3 ≥12.5 mg / m 3 ≥15 mg / m 3 ≥17.5 mg / m 3 ≥20 mg / m 3 ≥22.5 mg / m 3 ≥25 mg / m 3 or greater than or equal to 27.5 mg / m 3 Combinations of the above ranges are also possible (e.g., less than or equal to 30 mg / m³). 3 And greater than or equal to 0.00005 mg / m 3 Less than or equal to 20 mg / m 3 And greater than or equal to 0.001 mg / m 3 or less than or equal to 15 mg / m 3 And greater than or equal to 0.001 mg / m 3 Other ranges are also possible.

[0230] The average oil carryover of a nonwoven fiber web can be determined by: forming a sample for testing, generating an oil aerosol in the air, and placing a 100 cm² sample... 2The samples were exposed to oil aerosols for 70 minutes, and then the average concentration of oil in the air passing through the samples was determined. The samples to be tested were constructed by passing four layers, each 175 cm² in diameter. 2 The filter media are stacked together to form a filter. The oil used can be Shell Corena S3 R46, and it can have an average particle size of 0.7 micrometers and a maximum particle size of less than 1 micrometer.

[0231] Oil aerosols can be generated using an aerosol generator (e.g., from Topas). The aerosol generator allows air to flow through an oil reservoir at a flow rate of 50 L / min to generate an oil aerosol. Before impacting the sample, the oil aerosol can be combined with a certain amount of oil-free air flowing at a rate of 62 L / min to form a final oil aerosol flowing at a flow rate of 112 L / min and a surface velocity of 20 cm / s. The average oil concentration of this final oil aerosol is typically 2 g / (m²). 3 (Air). However, it should be understood that the actual oil concentration can vary slightly, and such slight variations are not expected to affect the measured average oil carryover. The oil concentration can be determined by measuring the rate of oil loss from the oil reservoir and dividing that value by the known rate of airflow through the oil reservoir.

[0232] The number and size of oil particles passing through the sample can be evaluated using a particle counter (e.g., from Palas), positioned on the side of the sample opposite to the side impacted by the oil aerosol. The particle counter can be used to perform such measurements every minute, and each measurement can measure the total number of particles of each size detected by the particle counter in the previous minute. For each particle counter measurement, the concentration of oil passing through the sample can be calculated as follows: based on the number and size of the measured particles, multiply the total volume of the counted particles by the known oil density, and then divide that number by the volume of air impacting the particle counter in the minute during the measurement. The average concentration of oil passing through the sample can be determined by averaging the oil concentrations measured by the particle counter over a 70-minute measurement period.

[0233] When the filter media comprises two or more nonwoven fiber webs, each nonwoven fiber web can independently have an average oil carry-through within one or more of the above-mentioned ranges.

[0234] The nonwoven fiber webs described herein can have a variety of suitable saturation pressure drops. In some embodiments, the saturation pressure drop of the nonwoven fiber web is greater than or equal to 10 mbar, greater than or equal to 15 mbar, greater than or equal to 20 mbar, greater than or equal to 25 mbar, greater than or equal to 30 mbar, greater than or equal to 40 mbar, greater than or equal to 50 mbar, greater than or equal to 60 mbar, greater than or equal to 75 mbar, greater than or equal to 100 mbar, greater than or equal to 125 mbar, greater than or equal to 150 mbar, greater than or equal to 175 mbar, greater than or equal to 200 mbar, greater than or equal to 250 mbar, greater than or equal to 300 mbar, greater than or equal to 350 mbar, greater than or equal to 400 mbar, greater than or equal to 450 mbar, greater than or equal to 500 mbar, greater than or equal to 550 mbar, greater than or equal to 600 mbar, greater than or equal to 650 mbar, or greater than or equal to 700 mbar. In some implementations, the saturation pressure drop of the nonwoven fiber web is less than or equal to 750 mbar, less than or equal to 700 mbar, less than or equal to 650 mbar, less than or equal to 600 mbar, less than or equal to 550 mbar, less than or equal to 500 mbar, less than or equal to 450 mbar, less than or equal to 400 mbar, less than or equal to 350 mbar, less than or equal to 300 mbar, less than or equal to 250 mbar, less than or equal to 200 mbar, less than or equal to 175 mbar, less than or equal to 150 mbar, less than or equal to 125 mbar, less than or equal to 100 mbar, less than or equal to 75 mbar, less than or equal to 60 mbar, less than or equal to 50 mbar, less than or equal to 40 mbar, less than or equal to 35 mbar, less than or equal to 30 mbar, less than or equal to 25 mbar, less than or equal to 20 mbar, or less than or equal to 15 mbar. Combinations of the above ranges are also possible (e.g., greater than or equal to 10 mbar and less than or equal to 750 mbar, greater than or equal to 20 mbar and less than or equal to 500 mbar, or greater than or equal to 30 mbar and less than or equal to 350 mbar). Other ranges are also possible.

[0235] The saturation pressure drop of a nonwoven fiber web can be determined by performing the measurement techniques described elsewhere in this document for determining the average oil carryover, and then measuring the pressure drop across the sample at the end of the measurement (i.e., 70 minutes after the sample has been exposed to the oil aerosol).

[0236] When the filter medium comprises two or more nonwoven fiber webs, each nonwoven fiber web may independently have a saturation pressure drop within one or more of the above ranges.

[0237] As described above, in some embodiments, the filter medium includes one or more additional layers besides the main filter layer. For example, the filter medium may also include a pre-filter layer, a support layer, a loosely woven nonwoven fabric, and / or an additional main filter layer. When present, the main filter layer can be particularly useful for removing particles from the fluid flowing through the filter medium. Other layers used in conjunction with the main filter layer may be suitable for other purposes. For example, some layers may be suitable for draining oil from the filter medium and / or reducing oil release into the process air. Non-limiting examples of suitable layer types for such layers include meltblown nonwoven fiber webs, spunbond nonwoven fiber webs, wet-laid nonwoven fiber webs, carded nonwoven fiber webs, and other non-wet-laid nonwoven fiber webs. Such layers may be laminated to each other and / or laminated to the main filter layer. In some embodiments, the filter medium also includes a discharge layer, such as a synthetic discharge layer.

[0238] In some embodiments, the filter medium comprises two or more single-layer types. For example, as described above, the filter medium may comprise two or more primary filter layers. The filter medium may also comprise two or more other types of layers (e.g., relatively open layers, such as support layers or loosely woven nonwoven fabrics). In some embodiments, the filter medium comprises both primary filter layers and relatively open layers. The filter medium may comprise multiple pairs of such layers (e.g., two or more pairs of primary filter layers and relatively open layers, three or more pairs of primary filter layers and relatively open layers, four or more pairs of primary filter layers and relatively open layers, or five or more pairs of primary filter layers and relatively open layers).

[0239] Filter media as a whole can possess a variety of suitable properties. Further details regarding some of the properties that filter media can have are provided below.

[0240] The filter media described in this article can have a variety of suitable weight per unit area. In some implementations, the weight per unit area of ​​the filter media is greater than or equal to 20 gsm, 30 gsm, 40 gsm, 50 gsm, 60 gsm, 70 gsm, 80 gsm, 90 gsm, 100 gsm, 110 gsm, 120 gsm, 130 gsm, 140 gsm, 150 gsm, 160 gsm, 170 gsm, 180 gsm, 190 gsm, 200 gsm, 225 gsm, 250 gsm, 275 gsm, 300 gsm, or 350 gsm. gsm, greater than or equal to 400 gsm, or greater than or equal to 450 gsm. In some implementations, the weight per unit area of ​​the filter media 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 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 190 gsm, less than or equal to 180 gsm, less than or equal to 170 gsm, less than or equal to 160 gsm, less than or equal to 150 gsm, less than or equal to 140 gsm, less than or equal to 130 gsm, less than or equal to 120 gsm, less than or equal to 110 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 50 gsm. The ranges are gsm, less than or equal to 40 gsm, or less than or equal to 30 gsm. Combinations of these ranges are also possible (e.g., greater than or equal to 20 gsm and less than or equal to 500 gsm, greater than or equal to 20 gsm and less than or equal to 400 gsm, greater than or equal to 20 gsm and less than or equal to 200 gsm, greater than or equal to 20 gsm and less than or equal to 150 gsm, greater than or equal to 20 gsm and less than or equal to 130 gsm, greater than or equal to 30 gsm and less than or equal to 400 gsm, or greater than or equal to 40 gsm and less than or equal to 250 gsm). Other ranges are also possible.

[0241] The weight per unit area of ​​the filter media can be determined according to ISO 536:2012.

[0242] The filter media described herein can have various suitable thicknesses. In some embodiments, the thickness of the filter media is greater than or equal to 100 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 400 micrometers, greater than or equal to 500 micrometers, greater than or equal to 750 micrometers, greater than or equal to 1000 micrometers, greater than or equal to 2000 micrometers, greater than or equal to 3000 micrometers, or greater than or equal to 4000 micrometers. In some embodiments, the thickness of the filter media is less than or equal to 5000 micrometers, less than or equal to 4000 micrometers, less than or equal to 3000 micrometers, less than or equal to 2000 micrometers, less than or equal to 1000 micrometers, less than or equal to 750 micrometers, less than or equal to 500 micrometers, less than or equal to 400 micrometers, less than or equal to 300 micrometers, less than or equal to 200 micrometers, or less than or equal to 200 micrometers. Combinations of the above ranges are also possible (e.g., greater than or equal to 100 micrometers and less than or equal to 5000 micrometers, greater than or equal to 200 micrometers and less than or equal to 5000 micrometers, greater than or equal to 200 micrometers and less than or equal to 3000 micrometers, or greater than or equal to 250 micrometers and less than or equal to 2000 micrometers). Other ranges are also possible.

[0243] The thickness of the filter medium can be determined according to ASTM D1777-96 (2019) at an applied pressure of 2 kPa.

[0244] The filter media described herein can have a variety of suitable average flow pore sizes. In some embodiments, the average flow pore size of the filter media is 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 1.75 micrometers, greater than or equal to 2 micrometers, greater than or equal to 2.25 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 17.5 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 flow pore size of the filter medium is 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 17.5 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, 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 2.25 micrometers, less than or equal to 2 micrometers, less than or equal to 1.75 micrometers, less than or equal to 1.5 micrometers, less than or equal to 1.25 micrometers, less than or equal to 1 micrometer, or less than or equal to 0.75 micrometers. Combinations of the above ranges are also possible (e.g., greater than or equal to 0.5 micrometers and less than or equal to 50 micrometers, greater than or equal to 0.5 micrometers and less than or equal to 35 micrometers, or greater than or equal to 1 micrometer and less than or equal to 15 micrometers). Other ranges are also possible.

[0245] The average flow orifice diameter of the filter medium can be determined according to ASTM F316-90 Method B (2019).

[0246] The filter media described herein can have a variety of suitable maximum pore sizes. In some embodiments, the maximum pore size of the filter media is greater than or equal to 1.5 micrometers, greater than or equal to 1.75 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 6 micrometers, greater than or equal to 8 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 17.5 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 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 implementations, the maximum pore size of the filter medium 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 17.5 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 8 micrometers, less than or equal to 6 micrometers, 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, or less than or equal to 1.75 micrometers. Combinations of the above ranges are also possible (e.g., greater than or equal to 1.5 micrometers and less than or equal to 100 micrometers, greater than or equal to 1.5 micrometers and less than or equal to 50 micrometers, or greater than or equal to 2.5 micrometers and less than or equal to 40 micrometers). Other ranges are also possible.

[0247] The maximum pore size of the filter medium can be determined according to ASTM F316-90 Method B (2019).

[0248] Some filter media described herein can have relatively high water repellency. In some embodiments, the water repellency of the filter media is greater than or equal to 0.5 inches of H2O, greater than or equal to 1 inch of H2O, greater than or equal to 2 inches of H2O, greater than or equal to 3 inches of H2O, greater than or equal to 4 inches of H2O, greater than or equal to 4.5 inches of H2O, greater than or equal to 5 inches of H2O, greater than or equal to 5.5 inches of H2O, greater than or equal to 6 inches of H2O, greater than or equal to 7 inches of H2O, greater than or equal to 8 inches of H2O, greater than or equal to 9 inches of H2O, greater than or equal to 10 inches of H2O, and greater than or equal to 12.5 inches of H2O. 0, greater than or equal to 15 inches H2O, greater than or equal to 20 inches H2O, greater than or equal to 30 inches H2O, greater than or equal to 40 inches H2O, greater than or equal to 50 inches H2O, greater than or equal to 75 inches H2O, greater than or equal to 100 inches H2O, greater than or equal to 125 inches H2O, greater than or equal to 150 inches H2O, greater than or equal to 175 inches H2O, greater than or equal to 200 inches H2O, greater than or equal to 225 inches H2O, greater than or equal to 250 inches H2O, or greater than or equal to 275 inches H2O. In some implementations, the water repellency of the filter media is less than or equal to 300 inches of H2O, less than or equal to 275 inches of H2O, less than or equal to 250 inches of H2O, less than or equal to 225 inches of H2O, less than or equal to 200 inches of H2O, less than or equal to 175 inches of H2O, less than or equal to 150 inches of H2O, less than or equal to 125 inches of H2O, less than or equal to 100 inches of H2O, less than or equal to 75 inches of H2O, less than or equal to 50 inches of H2O, less than or equal to 40 inches of H2O, and less than or equal to... 30-inch H2O, less than or equal to 20-inch H2O, less than or equal to 15-inch H2O, less than or equal to 12.5-inch H2O, less than or equal to 10-inch H2O, less than or equal to 9-inch H2O, less than or equal to 8-inch H2O, less than or equal to 7-inch H2O, less than or equal to 6-inch H2O, less than or equal to 5.5-inch H2O, less than or equal to 5-inch H2O, less than or equal to 4.5-inch H2O, less than or equal to 4-inch H2O, less than or equal to 3-inch H2O, or less than or equal to 2-inch H2O.Combinations of the above ranges are also possible (e.g., greater than or equal to 0.5 inches of H2O and less than or equal to 300 inches of H2O, greater than or equal to 0.5 inches of H2O and less than or equal to 100 inches of H2O, greater than or equal to 4 inches of H2O and less than or equal to 40 inches of H2O, greater than or equal to 7 inches of H2O and less than or equal to 20 inches of H2O, greater than or equal to 20 inches of H2O and less than or equal to 35 inches of H2O, greater than or equal to 4 inches of H2O and less than or equal to 300 inches of H2O, greater than or equal to 5 inches of H2O and less than or equal to 200 inches of H2O, or greater than or equal to 10 inches of H2O and less than or equal to 150 inches of H2O). Other ranges are also possible.

[0249] The water repellency of a filter medium can be determined by performing a hydrostatic head test (HHT), which determines the height of water that the medium will hold up before a predetermined amount of liquid passes through it. Filter media with a higher HHT value exhibit greater resistance to liquid permeation than filter media with a lower HHT value. The HHT can be performed on an FX3000 Hydrotester III instrument according to the standards used to determine resistance to water permeation: BS EN 20811:1992 (UK), EN 20811:1992, and ISO 811:1981 (International).

[0250] In some implementations, the filter media may be characterized by a name indicating a range of efficiency levels. As an example, the filter media may be a high-efficiency particulate air (HEPA) filter or an ultra-low particulate air (ULPA) filter. These filters are required to remove particulates at the efficiency levels specified by EN1822:2009. In some implementations, the filter media removes particles at the most penetrating size (the particle size with the highest penetration rate) with an efficiency greater than 99.95% (H 13), greater than 99.995% (H 14), greater than 99.9995% (U 15), greater than 99.99995% (U 16), or greater than 99.999995% (U 17). The filter media described herein may also be M5, M6, F7, F8, F9, E10, E11, or E12 filter media according to EN 779 (2012) and / or EN 1822:2009. These filter media must exhibit the following efficiencies: 40% to 60% for particles with a diameter of 0.4 micrometers; 60% to 80% for particles with a diameter of 0.4 micrometers; 80% to 90% for particles with a diameter of 0.4 micrometers; 90% to 95% for particles with a diameter of 0.4 micrometers; greater than or equal to 95% for particles with a diameter of 0.4 micrometers; greater than or equal to 85% for particles at the most penetrating particle size; greater than or equal to 95% for particles at the most penetrating particle size; and greater than or equal to 99.5% for particles at the most penetrating particle size. As a third example, the filter media may be ePM1, ePM2.5, ePM10, or ISO Coarse filter media according to ISO 16890. As a fourth example, the filter media can be MERV 8, MERV 9, MERV 10, MERV 11, MERV 12, MERV 13, MERV 14, MERV 15, or MERV 16 filter media according to ANSI and ASHRAE 52.2.

[0251] In some embodiments, the filter media described herein have a relatively high initial dioctyl phthalate (DOP) γ value. For filter media with an efficiency less than or equal to 99.95%, the initial DOP γ can be measured at 0.3 micrometers; for filter media with an efficiency greater than 99.95% but less than 99.995%, the initial DOP γ can be measured at 0.19 micrometers; and for filter media with an efficiency greater than or equal to 99.995%, the initial DOP γ can be measured at the most penetrating particle size. The initial DOP γ at a specific particle size (e.g., 0.3 micrometers, 0.19 micrometers, the most penetrating particle size) is defined by the following formula: DOP γ = (-log10(initial DOP penetration at particle size, % / 100%) / (initial air resistance, mm H2O)) × 100.

[0252] The penetration rate (usually expressed as a percentage) is defined as follows: Penetration rate (%) = (C / C0) * 100%, where C is the particle concentration after passing through the filter media, and C0 is the particle concentration before passing through the filter media. The initial penetration rate of DOP particles of a specific size can be measured by blowing DOP particles of that size through the filter media and measuring the percentage of particles that penetrate through it.

[0253] Testing for particles with a diameter of 0.3 micrometers can be performed according to ASTM D2986 (1999). The following is an exemplary method for performing this test, but other such methods are possible. An automatic permeameter and filter tester, available from AirTechniques International, can be used to measure the permeameter at 100 cm upstream of the filter medium. 2 DOP particles are blown at a surface velocity of 5.33 cm / s across the surface area. The DOP particles can have a mass-average diameter of 0.3 μm (and a count median diameter of 0.18 μm and a geometric standard deviation of less than 1.6 μm). Upstream and downstream particle concentrations can be measured using a cohesive particle counter. DOP particles can be blown at the upstream surface of the filter media until the transmittance is determined to be stable using a TDA-100P automatic permeameter and filter tester.

[0254] Testing for particles with a diameter of 0.19 micrometers can be performed using methods known to those skilled in the art. The following is an exemplary such method. In short, TSI 3160 can be used at a depth of 100 cm on the upstream surface of the filter media. 2DOP particles are blown through the filter media at a surface velocity of 2.5 cm / s and an airflow rate of 12 L / min. The average particle size of the DOP particles can be 0.19 μm. DOP particles can be blown onto the upstream surface of the filter media for a period of 20 to 400 seconds, thus obtaining at least 70 downstream counts. The upstream and downstream particle concentrations can be measured throughout the measurement period using a cohesive particle counter, and the γ value can be calculated using the total upstream and downstream particle counts throughout the measurement period.

[0255] The test of penetration rate at the most penetrating particle size can be performed by methods known to those skilled in the art. An exemplary such method is given below. In this method, the steps described above for 0.19 micrometer diameter particles are followed, except that DOP particles of a certain size range can be blown onto the upstream surface of the filter media. The particle size at which the highest penetration rate is measured is then considered the most penetrating particle size, and the penetration rate at that particle size is used in the γ calculation. Alternatively, for such analysis, TSI 3160 can be used at 100 cm⁻¹ on the upstream surface of the filter media. 2 DOP particle groups with different average particle sizes are sequentially blown into the filter media. The particle groups can be blown into the upstream surface of the filter media in order of increasing average diameter, and the particle groups can have an average diameter set of 0.03 μm, 0.06 μm, 0.08 μm, 0.13 μm, and 0.2 μm. Each particle group can be blown in the same manner as described in the preceding paragraph.

[0256] The air resistance of the filter media can be determined using the same steps described elsewhere in this document for the air resistance of nonwoven fiber webs.

[0257] In some implementations, the initial DOP γ of the filter media is greater than or equal to 6, greater than or equal to 6.5, greater than or equal to 7, greater than or equal to 7.5, greater than or equal to 8, greater than or equal to 8.5, greater than or equal to 9, greater than or equal to 9.5, greater than or equal to 10, greater than or equal to 11, greater than or equal to 12, greater than or equal to 13, greater than or equal to 14, greater than or equal to 15, greater than or equal to 17.5, greater than or equal to 20, greater than or equal to 22.5, greater than or equal to 25, or greater than or equal to 27.5. In some implementations, the initial DOP γ of the filter media is less than or equal to 30, less than or equal to 27.5, less than or equal to 25, less than or equal to 22.5, less than or equal to 20, less than or equal to 17.5, less than or equal to 15, less than or equal to 14, less than or equal to 13, less than or equal to 12, less than or equal to 11, less than or equal to 10, less than or equal to 9.5, less than or equal to 9, less than or equal to 8.5, less than or equal to 8, less than or equal to 7.5, less than or equal to 7, or less than or equal to 6.5. Combinations of the above ranges are also possible (e.g., greater than or equal to 6 and less than or equal to 30, greater than or equal to 8 and less than or equal to 30, greater than or equal to 9 and less than or equal to 30, greater than or equal to 9 and less than or equal to 25, greater than or equal to 9 and less than or equal to 20, or greater than or equal to 10 and less than or equal to 25). Other ranges are also possible.

[0258] The filter media described herein can have a variety of suitable air resistances. In some embodiments, the air resistance of the filter media is greater than or equal to 0.5 Pa, greater than or equal to 0.6 Pa, greater than or equal to 0.8 Pa, greater than or equal to 1 Pa, greater than or equal to 2 Pa, greater than or equal to 5 Pa, greater than or equal to 7.5 Pa, greater than or equal to 10 Pa, greater than or equal to 20 Pa, greater than or equal to 25 Pa, greater than or equal to 28 Pa, greater than or equal to 30 Pa, greater than or equal to 35 Pa, greater than or equal to 40 Pa, greater than or equal to 45 Pa, greater than or equal to 50 Pa, greater than or equal to 55 Pa, greater than or equal to 60 Pa, greater than or equal to 75 Pa, greater than or equal to 100 Pa, greater than or equal to 200 Pa, greater than or equal to 300 Pa, greater than or equal to 400 Pa, greater than or equal to 500 Pa, greater than or equal to 600 Pa, or greater than or equal to 700 Pa. In some implementations, the air resistance of the filter medium is less than or equal to 800 Pa, less than or equal to 700 Pa, less than or equal to 600 Pa, less than or equal to 500 Pa, less than or equal to 400 Pa, less than or equal to 300 Pa, less than or equal to 200 Pa, less than or equal to 100 Pa, less than or equal to 75 Pa, less than or equal to 60 Pa, less than or equal to 55 Pa, less than or equal to 50 Pa, less than or equal to 45 Pa, less than or equal to 40 Pa, less than or equal to 35 Pa, less than or equal to 30 Pa, less than or equal to 28 Pa, less than or equal to 25 Pa, less than or equal to 20 Pa, less than or equal to 10 Pa, less than or equal to 7.5 Pa, less than or equal to 5 Pa, less than or equal to 2 Pa, less than or equal to 1 Pa, less than or equal to 0.8 Pa, or less than or equal to 0.6 Pa. Combinations of the above ranges are also possible (e.g., greater than or equal to 0.5 Pa and less than or equal to 800 Pa, greater than or equal to 0.5 Pa and less than or equal to 60 Pa, greater than or equal to 0.8 Pa and less than or equal to 30 Pa, or greater than or equal to 2 Pa and less than or equal to 800 Pa). Other ranges are also possible.

[0259] In some implementations, the filter media has a relatively high dry tensile strength in the machine direction. The dry tensile strength in the machine direction can be greater than or equal to 0.25 kN / m, greater than or equal to 0.5 kN / m, greater than or equal to 0.75 kN / m, greater than or equal to 1 kN / m, greater than or equal to 1.5 kN / m, greater than or equal to 2 kN / m, greater than or equal to 2.5 kN / m, greater than or equal to 3 kN / m, greater than or equal to 4 kN / m, greater than or equal to 5 kN / m, greater than or equal to 6 kN / m, greater than or equal to 7.5 kN / m, greater than or equal to 10 kN / m, or greater than or equal to 12.5 kN / m. The dry tensile strength in the machine direction can be less than or equal to 15 kN / m, less than or equal to 12.5 kN / m, less than or equal to 10 kN / m, less than or equal to 7.5 kN / m, less than or equal to 6 kN / m, less than or equal to 5 kN / m, less than or equal to 4 kN / m, less than or equal to 3 kN / m, less than or equal to 2.5 kN / m, less than or equal to 2 kN / m, less than or equal to 1.5 kN / m, less than or equal to 1 kN / m, less than or equal to 0.75 kN / m, or less than or equal to 0.5 kN / m. Combinations of the above ranges are also possible (e.g., greater than or equal to 0.25 kN / m and less than or equal to 15 kN / m). Other ranges are also possible.

[0260] The dry tensile strength of the filter media in the machine direction can be determined using the same steps described elsewhere in this document for the dry tensile strength of nonwoven fiber webs in the machine direction.

[0261] In some implementations, the filter media has a relatively high machine-direction Gurley stiffness. The machine-direction Gurley stiffness can be 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 600 mg, greater than or equal to 750 mg, greater than or equal to 1000 mg, greater than or equal to 1250 mg, greater than or equal to 1500 mg, greater than or equal to 2000 mg, greater than or equal to 2500 mg, greater than or equal to 3000 mg, greater than or equal to 3500 mg, greater than or equal to 4000 mg, or greater than or equal to 4500 mg. The Gurley stiffness in the machine direction can be less than or equal to 5000 mg, less than or equal to 4500 mg, less than or equal to 4000 mg, less than or equal to 3500 mg, less than or equal to 3000 mg, less than or equal to 2500 mg, less than or equal to 2000 mg, less than or equal to 1500 mg, less than or equal to 1250 mg, less than or equal to 1000 mg, less than or equal to 750 mg, less than or equal to 600 mg, less than or equal to 500 mg, or less than or equal to 400 mg. Combinations of the above ranges are also possible (e.g., greater than or equal to 300 mg and less than or equal to 5000 mg). Other ranges are also possible.

[0262] The Gurley stiffness of the filter media in the machine direction is determined by the same steps described elsewhere in this document for the Gurley stiffness of nonwoven fiber webs in the machine direction.

[0263] The filter media described herein can have various oil grades. In some embodiments, the filter media has an oil grade greater than or equal to 0, greater than or equal to 1, greater than or equal to 2, greater than or equal to 3, greater than or equal to 4, or greater than or equal to 5. In some embodiments, the filter media has an oil grade less than or equal to 6, less than or equal to 5, less than or equal to 4, less than or equal to 3, less than or equal to 2, or less than or equal to 1. Combinations of the above ranges are also possible (e.g., greater than or equal to 0 and less than or equal to 6, greater than or equal to 1 and less than or equal to 6, greater than or equal to 2 and less than or equal to 5, greater than or equal to 3 and less than or equal to 4, or greater than or equal to 5 and less than or equal to 6). Other ranges are also possible.

[0264] The oil grade of the filter media can be determined using the same steps described elsewhere in this document regarding the oil grade of nonwoven fiber webs.

[0265] The filter media described herein can have a variety of suitable poly(urethane) wicking heights. In some embodiments, the poly(urethane) wicking height of the filter media is 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 22.5 mm, less than or equal to 20 mm, less than or equal to 17.5 mm, less than or equal to 15 mm, less than or equal to 12.5 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 2 mm, or less than or equal to 1 mm. In some embodiments, the polyurethane (urethane) wicking height of the filter media is greater than or equal to 0 mm, greater than or equal to 1 mm, greater than or equal to 2 mm, greater than or equal to 5 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 17.5 mm, greater than or equal to 20 mm, greater than or equal to 22.5 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. Combinations of the above ranges are also possible (e.g., less than or equal to 50 mm and greater than or equal to 0 mm, less than or equal to 20 mm and greater than or equal to 0 mm, or less than or equal to 10 mm and greater than or equal to 0 mm). Other ranges are also possible.

[0266] The poly(urethane) wicking height of the filter media can be determined by the process described in Implementation Scheme 5.

[0267] The filter media described herein can have a variety of suitable average oil carryover. In some embodiments, the average oil carryover of the filter media is less than or equal to 30 mg / m³. 3 Less than or equal to 27.5 mg / m 3 Less than or equal to 25 mg / m 3 Less than or equal to 22.5 mg / m 3 Less than or equal to 20 mg / m 3 Less than or equal to 17.5 mg / m 3 Less than or equal to 15 mg / m 3 Less than or equal to 12.5 mg / m³ 3 Less than or equal to 10 mg / m 3 Less than or equal to 7.5 mg / m 3 Less than or equal to 5 mg / m 3 Less than or equal to 2 mg / m 3 Less than or equal to 1 mg / m3 Less than or equal to 0.75 mg / m 3 Less than or equal to 0.5 mg / m 3 Less than or equal to 0.2 mg / m 3 Less than or equal to 0.1 mg / m 3 Less than or equal to 0.075 mg / m 3 Less than or equal to 0.05 mg / m 3 Less than or equal to 0.02 mg / m 3 Less than or equal to 0.01 mg / m³ 3 Less than or equal to 0.0075 mg / m 3 Less than or equal to 0.005 mg / m 3 Less than or equal to 0.002 mg / m³ 3 Less than or equal to 0.001 mg / m³ 3 Less than or equal to 0.00075 mg / m 3 Less than or equal to 0.0005 mg / m 3 Less than or equal to 0.0002 mg / m³ 3 or less than or equal to 0.0001 mg / m 3 In some implementations, the average oil carryover of the filter media is greater than or equal to 0.00005 mg / m³. 3 ≥0.0001 mg / m 3 ≥0.0002 mg / m 3 ≥0.0005 mg / m 3 ≥0.00075 mg / m 3 ≥0.001 mg / m 3 ≥0.002 mg / m 3 ≥0.005 mg / m 3 ≥0.0075 mg / m 3 ≥0.01 mg / m 3 ≥0.02 mg / m 3 ≥0.05 mg / m 3 ≥0.075 mg / m 3 ≥0.1 mg / m 3 ≥0.2 mg / m 3 ≥0.5 mg / m 3 ≥0.75 mg / m 3 ≥1 mg / m3 ≥2 mg / m 3 ≥5 mg / m 3 ≥7.5 mg / m 3 ≥12.5 mg / m 3 ≥15 mg / m 3 ≥17.5 mg / m 3 ≥20 mg / m 3 ≥22.5 mg / m 3 ≥25 mg / m 3 or greater than or equal to 27.5 mg / m 3 Combinations of the above ranges are also possible (e.g., less than or equal to 30 mg / m³). 3 And greater than or equal to 0.00005 mg / m 3 Less than or equal to 20 mg / m 3 And greater than or equal to 0.001 mg / m 3 or less than or equal to 15 mg / m³ 3 And greater than or equal to 0.001 mg / m 3 Other ranges are also possible.

[0268] The average oil carryover of the filter media can be determined using the same steps described elsewhere in this document regarding the average oil carryover of nonwoven fiber webs.

[0269] The filter media described herein can have a variety of suitable saturation pressure drops. In some embodiments, the saturation pressure drop of the filter media is greater than or equal to 10 mbar, greater than or equal to 15 mbar, greater than or equal to 20 mbar, greater than or equal to 25 mbar, greater than or equal to 30 mbar, greater than or equal to 40 mbar, greater than or equal to 50 mbar, greater than or equal to 60 mbar, greater than or equal to 75 mbar, greater than or equal to 100 mbar, greater than or equal to 125 mbar, greater than or equal to 150 mbar, greater than or equal to 175 mbar, greater than or equal to 200 mbar, greater than or equal to 250 mbar, greater than or equal to 300 mbar, greater than or equal to 350 mbar, greater than or equal to 400 mbar, greater than or equal to 450 mbar, greater than or equal to 500 mbar, greater than or equal to 550 mbar, greater than or equal to 600 mbar, greater than or equal to 650 mbar, or greater than or equal to 700 mbar. In some implementations, the saturation pressure drop of the filter medium is less than or equal to 750 mbar, less than or equal to 700 mbar, less than or equal to 650 mbar, less than or equal to 600 mbar, less than or equal to 550 mbar, less than or equal to 500 mbar, less than or equal to 450 mbar, less than or equal to 400 mbar, less than or equal to 350 mbar, less than or equal to 300 mbar, less than or equal to 250 mbar, less than or equal to 200 mbar, less than or equal to 175 mbar, less than or equal to 150 mbar, less than or equal to 125 mbar, less than or equal to 100 mbar, less than or equal to 75 mbar, less than or equal to 60 mbar, less than or equal to 50 mbar, less than or equal to 40 mbar, less than or equal to 35 mbar, less than or equal to 30 mbar, less than or equal to 25 mbar, less than or equal to 20 mbar, or less than or equal to 15 mbar. Combinations of the above ranges are also possible (e.g., greater than or equal to 10 mbar and less than or equal to 750 mbar, greater than or equal to 20 mbar and less than or equal to 500 mbar, or greater than or equal to 30 mbar and less than or equal to 350 mbar). Other ranges are also possible.

[0270] The saturation pressure drop of the filter medium can be determined using the same steps described elsewhere in this document for the saturation pressure drop of nonwoven fiber webs.

[0271] The filter media described herein are suitable for a wide range of applications. Some of the filter media described herein are suitable for air filtration and / or for placement in air filters. As described elsewhere herein, some filter media are suitable for HEPA and / or ULPA filters. Other examples of suitable types of filters in which the filter media described herein can be placed include HVAC filters, heavy-duty air filters, gas turbine filters, liquid filters, and coalescer filters. Suitable coalescer filters include coalescer filters for air / oil separation and coalescer filters for liquid / liquid separation (e.g., fuel / water separation, such as jet engine fuel / water separation).

[0272] In some implementations, the filter media described herein may be an assembly of a filter element. That is, the filter media may be incorporated into an article of manufacture suitable for end-user use.

[0273] Non-limiting examples of suitable filter elements include flat-plate filters, V-type filters (including, for example, 1 to 24 Vs), cartridge filters, cylindrical filters, and conical filters. Filter elements can have any suitable height (e.g., 2 inches to 124 inches for flat-plate filters, 4 inches to 124 inches for V-type filters, and 1 inch to 124 inches for cartridge and cylindrical filter media). Filter elements can also have any suitable width (2 inches to 124 inches for flat-plate filters and 4 inches to 124 inches for V-type filters). Some filter media (e.g., cartridge and cylindrical filter media) may be characterized by their diameter rather than their width; these filter media can have any suitable diameter (e.g., 1 inch to 124 inches). Filter elements typically include a frame, which can be made of one or more materials (e.g., cardboard, aluminum, steel, alloys, wood, and polymers).

[0274] In some implementations, the filter media described herein may be an assembly of a filter element and may be pleated. The pleat height and pleat density (the number of pleats per unit length of media) can be selected as needed. In some embodiments, the pleat height can be greater than or equal to 10 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 35 mm, greater than or equal to 40 mm, greater than or equal to 45 mm, greater than or equal to 50 mm, greater than or equal to 53 mm, greater than or equal to 55 mm, greater than or equal to 60 mm, greater than or equal to 65 mm, greater than or equal to 70 mm, greater than or equal to 75 mm, greater than or equal to 80 mm, greater than or equal to 85 mm, greater than or equal to 90 mm, greater than or equal to 95 mm, 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 175 mm, greater than or equal to 200 mm, greater than or equal to 225 mm, greater than or equal to 250 mm, greater than or equal to 275 mm, greater than or equal to 300 mm, greater than or equal to 325 mm, greater than or equal to 350 mm, or greater than or equal to 375 mm. mm, greater than or equal to 400 mm, greater than or equal to 425 mm, greater than or equal to 450 mm, greater than or equal to 475 mm, or greater than or equal to 500 mm. In some embodiments, the pleat height is less than or equal to 510 mm, less than or equal to 500 mm, less than or equal to 475 mm, less than or equal to 450 mm, less than or equal to 425 mm, less than or equal to 400 mm, less than or equal to 375 mm, less than or equal to 350 mm, less than or equal to 325 mm, less than or equal to 300 mm, less than or equal to 275 mm, less than or equal to 250 mm, less than or equal to 225 mm, less than or equal to 200 mm, less than or equal to 175 mm, less than or equal to 150 mm, less than or equal to 125 mm, less than or equal to 100 mm, less than or equal to 95 mm, less than or equal to 90 mm, less than or equal to 85 mm, less than or equal to 80 mm, less than or equal to 75 mm, less than or equal to 70 mm, less than or equal to 65 mm, less than or equal to 60 mm, less than or equal to 55 mm, less than or equal to 53 mm, 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 35 mm. mm, less than or equal to 30 mm, less than or equal to 25 mm, less than or equal to 20 mm, or less than or equal to 15 mm. Combinations of the above ranges are also possible (e.g., greater than or equal to 10 mm and less than or equal to 510 mm, or greater than or equal to 10 mm and less than or equal to 100 mm). Other ranges are also possible.

[0275] In some implementations, the pleat density of the filter medium is greater than or equal to 5 pleats per 100 mm, greater than or equal to 6 pleats per 100 mm, greater than or equal to 10 pleats per 100 mm, greater than or equal to 15 pleats per 100 mm, greater than or equal to 20 pleats per 100 mm, greater than or equal to 25 pleats per 100 mm, greater than or equal to 28 pleats per 100 mm, greater than or equal to 30 pleats per 100 mm, or greater than or equal to 35 pleats per 100 mm. In some embodiments, the pleat density of the filter media is less than or equal to 40 pleats per 100 mm, less than or equal to 35 pleats per 100 mm, less than or equal to 30 pleats per 100 mm, less than or equal to 28 pleats per 100 mm, less than or equal to 25 pleats per 100 mm, less than or equal to 20 pleats per 100 mm, less than or equal to 15 pleats per 100 mm, less than or equal to 10 pleats per 100 mm, or less than or equal to 6 pleats per 100 mm. Combinations of the above ranges are also possible (e.g., greater than or equal to 5 pleats per 100 mm and less than or equal to 40 pleats per 100 mm, greater than or equal to 6 pleats per 100 mm and less than or equal to 40 pleats per 100 mm, or greater than or equal to 25 pleats per 100 mm and less than or equal to 28 pleats per 100 mm). Other ranges are also possible.

[0276] Other pleat heights and densities are also possible. For example, the filter media in a flat panel filter or V-filter can have a pleat height of ¼ inch to 24 inches and / or a pleat density of 1 pleat / inch to 50 pleats / inch. As another example, the filter media in a cartridge filter or cone filter can have a pleat height of ¼ inch to 24 inches and / or a pleat density of ½ pleat / inch to 100 pleats / inch. In some embodiments, the pleats are separated by a pleat separator made of, for example, polymers, glass, aluminum, and / or cotton. In other embodiments, the filter element does not contain a pleat separator. The filter media can be wire-backed or self-supporting.

[0277] In some implementations, the filter medium comprises one or more layers that are encapsulated.

[0278] Example 1

[0279] This embodiment describes the manufacture and testing of filter media containing additives with different functional groups.

[0280] Each filter media is manufactured by introducing a fluid containing precursors into an H 14 filter media comprising microglass fibers and chopped glass fibers. The precursors used include methyltrimethoxysilane, n-propyltrimethoxysilane, n-octyltrimethoxysilane, hexadecyltrimethoxysilane, and octadecyltrimethoxysilane. A fluid containing the precursors is formed by mixing the precursors with water in a laboratory mixer for five minutes to form a solution or dispersion of the precursors in water at 0.3% by weight. The H 14 filter media is placed on a line, and then the H 14 filter media and the line are immersed together in the fluid containing the precursors for ten seconds. After removal from the fluid containing the precursors, the H 14 filter media and the line are exposed to a vacuum and then dried in a light dryer. Finally, the precursor-coated H 14 filter media is cured in an oven and then post-cured to form the final filter media containing cured water-repellent additives.

[0281] Figure 3 The figure shows the γ values ​​of each of the filter media containing an additive formed from one of the precursors described in the preceding paragraphs. In this figure, the provided labels identify the precursors. As can be seen from the data shown, the filter media containing an additive formed from a precursor having longer water-repellent functional groups has a higher γ value than the filter media containing a water-repellent additive having shorter water-repellent functional groups.

[0282] The water repellency of each filter media was also measured. All observed values ​​were high enough to make the filter media suitable for applications requiring water repellency (e.g., over 10 inches of H2O).

[0283] Example 2

[0284] This embodiment describes the manufacture and testing of a filter media containing water-repellent additives and fluorinated resins. The filter media is compared with filter media that do not contain any or both of these substances.

[0285] A filter medium comprising both a water-repellent additive and a fluorinated resin was prepared as described in Example 1, except that a dispersion of the resin and the water-repellent additive was prepared and mixed, rather than a mixture of only the water-repellent additive in water. This mixture comprised 1.5% by weight solids, and the water-repellent additive comprised 20% by weight of the mixture. The resin used was a PVDF-acrylic copolymer. The precursor used was octadecyltrimethoxysilane. After exposure to the mixture, the nonwoven fiber web was 4% to 5% heavier than before exposure. A filter medium comprising only the fluorinated resin was prepared in the same manner, except that the dispersion did not contain the water-repellent additive. A filter medium comprising only the water-repellent additive was prepared as described in Example 1.

[0286] Figure 4 The water repellency of various filter media is shown. From Figure 4The results show that filter media containing both an additive formed from octadecyltrimethoxysilane and PVDF-acrylic copolymer resin exhibit improved water repellency compared to filter media containing neither of these substances (the latter being referred to as "base media"). Therefore, it is believed that PVDF-acrylic copolymer and octadecyltrimethoxysilane work synergistically.

[0287] Example 3

[0288] This embodiment describes the manufacture and testing of a filter medium containing water-repellent additives and additives containing polar functional groups. The filter medium also contains a PVDF-acrylate copolymer. This filter medium is compared with a filter medium that does not contain additives containing polar functional groups.

[0289] The filter media is manufactured as described in Example 2, except that each additive accounts for 10% by weight of the mixture. The water-repellent additive is octadecyltrimethoxysilane, and the additive containing polar functional groups is aminopropyltrimethoxysilane. Figure 5 The water repellency of the three filter media tested is shown. From Figure 5 It is evident that the filter media containing all three substances (filter media 1) has higher water repellency than both the filter media without aminopropyltrimethoxysilane (filter media 2) and the filter media without both additives and PVDF-acrylic copolymers (filter media 3).

[0290] Example 4

[0291] This embodiment describes the manufacture and testing of a filter medium comprising either or both of a first water-repellent additive and a second water-repellent additive, wherein the first water-repellent additive comprises a water-repellent functional group having an alkyl group having three or more carbon atoms, and the second water-repellent additive is a fluorinated water-repellent additive.

[0292] The filter media is manufactured as described in Example 2, except that: an acrylic resin is used instead of a PVDF-acrylic copolymer; the precursor of the first water-repellent additive is hexadecyltrimethoxysilane; and the dispersion further comprises perfluoropoly(ether) (polymer 1) or contains a structure having -C4F m R y The second water-repellent additive is one of the polymers (polymer 2) with fluorinated side chains (where m≥1); the weight ratio of the resin to the sum of the weights of the first and second water-repellent additives is 4:1; the dispersion is formed by mixing the precursor and resin with water for five minutes using a laboratory mixer to form a 99% water dispersion.

[0293] Figure 6 and Figure 7 The water repellency of each filter medium is shown. Figure 6 The water repellency of the filter media containing polymer 1 is shown, and Figure 7 The water repellency of the filter media containing polymer 2 is shown. As can be seen in the two figures, the water repellency of the filter media is higher than that predicted by the line of the mixture (the line predicting the physical properties of the mixture as a composition-weighted average of the physical properties of the components of the mixture). Therefore, the mixture containing both the first and second water-repellent additives exhibits unexpectedly high water repellency.

[0294] Figure 8 and Figure 9 The oil grade for each filter medium is shown. Figure 8 The oil grade of the filter media containing polymer 1 is shown, and Figure 9 The oil grades of filter media containing polymer 2 are shown. As can be seen from these figures, the inclusion of water-repellent additives, which are fluorinated polymers, improves the oil grade of the filter media.

[0295] Example 5

[0296] This embodiment describes the manufacture and testing of filter media containing various water-repellent additives.

[0297] Five different filter media containing different water-repellent additives were manufactured. The composition of the water-repellent additives and resins present in the filter media is summarized in Table 2 below.

[0298] Table 2.

[0299]

[0300] The poly(urethane) wicking height was then measured for each filter medium on three different 3.5”×2” samples. Each 3.5”×2” sample was placed vertically in a 250 mL beaker containing a certain amount of poly(urethane) binder. The sample was placed in the beaker to a depth such that its lowest point was immersed to a depth of 10 mm ± 1 mm, and then left there for two minutes. At the end of the two minutes, each sample was removed from its beaker, and excess resin was wiped off the surface of the filter medium. The distance the resin traveled up the filter medium along both edges was then measured (i.e., the difference between the resin height immediately after the sample was placed in the beaker and the resin height at the end of the two minutes). Finally, the six values ​​for each filter medium (i.e., two measurements for each of the three samples) were averaged to obtain the final poly(urethane) wicking height.

[0301] Figure 10 Photographs of the five samples at the end of the measurement are shown, as well as Figure 11The measured wicking heights of poly(urethane) are shown. As can be seen from these figures, the inclusion of fluorinated water-repellent additives reduces the wicking height of poly(urethane).

[0302] Example 6

[0303] This embodiment describes the manufacture and testing of filter media containing various water-repellent additives.

[0304] Eight types of filter media are manufactured: four Type I coalescing grades and four Type II coalescing grades. The characteristics of the coalescing grades are also shown in Tables 3 and 4 below.

[0305] Table 3 (Characteristics of Coalescing Class A).

[0306]

[0307] Table 4 (Characteristics of Coalescing Class B).

[0308]

[0309] Different water-repellent additives or combinations of water-repellent additives were added to each of the four filter media of each type of coalescer class using the same steps described in Example 1. The added water-repellent additives and combinations thereof are those sample numbers 2 to 4 shown in Table 2.

[0310] Figure 12 and Figure 13 The saturation pressure drop and average oil carryover for each filter medium are shown. As can be seen from these figures, filter media containing fluorinated water-repellent additives, such as fluorinated polymers, exhibit a lower average oil carryover than filter media without such additives. It can also be seen from these figures that filter media containing both water-repellent additives with alkyl groups of three or more carbon atoms and fluorinated polymers have a lower saturation pressure drop than other filter media.

[0311] Example 7

[0312] This example describes the effect of PVOH on filter media with different resins.

[0313] As shown in Table 5, filter media containing or without PFAS resins, and with or without PVOH fibers, were investigated. γ, DOP penetration, and air resistance were measured according to methods described elsewhere in this document. Sample A and Sample B differ only in the type of resin used. Sample B and Sample C differ only in the amount of PVOH used.

[0314] Table 5. Components of the filter media and γ

[0315]

[0316] As shown in Table 5, the use of a PFAS-free alternative resin in Sample B resulted in a lower saturation γ than in Sample A. Although the removal of PVOH fibers improved the saturation γ in Sample C, it also led to a decrease in wet strength (as measured elsewhere in this document), rendering the sample unprocessable.

[0317] Example 8

[0318] This embodiment describes the fabrication and testing of nonwoven fiber web samples containing various different fibers.

[0319] The nonwoven fiber web samples comprise fine microglass fibers (average diameter less than or equal to 1 micrometer), glass fibers with medium diameter (average diameter greater than 1 micrometer and less than or equal to 6 micrometers), coarse glass fibers (average diameter greater than 6 micrometers), bicomponent fibers, PVOH fibers, and / or fibrillated fibers (lyocell fibers). The amount of each type of fiber in each sample is detailed in Table 6. The samples in Table 6 are nonwoven fiber web samples before the optional addition of any resins and / or additives.

[0320] Table 6. Composition of nonwoven fiber web samples.

[0321]

[0322] Figure 14 This is a graph showing the γ values ​​for samples 1 through 3 (from left to right) in Table 6. The graph shows that γ decreases with increasing PVOH content. γ was measured as described elsewhere in this document.

[0323] In sample 4, fibrillated lyocell fibers were added to sample 1, and the level of microglass fibers with medium diameter was correspondingly reduced. Figure 15 This is a diagram of a nonwoven fiber web sample with a composition corresponding to sample 4, where the fibrillated lyocell fibers have different fibrillation levels. (See diagram for reference.) Figure 15 As shown, the use of fibrillated lyocell fibers with higher CSF values ​​increased γ. γ was measured as described elsewhere in this document. Sample 4 also exhibited higher wet strength and better processability than Sample 1.

[0324] The flame retardancy of samples 3 and 4 in Table 6 was then tested using DIN 53438 (June 1984). Each sample passed the test, indicating that the presence of the tested amount of PVOH fibers or fibrillated fibers did not adversely affect the flame retardancy.

[0325] In samples 5 through 8, there were no PVOH or bicomponent fibers, and the amount of fibrillated lyocell fibers varied (e.g., fibrillated fibers were used instead of a corresponding amount of glass fibers with a medium diameter). Figure 16As shown, the base γ decreases with increasing fibrillated lyocell fiber content. γ was measured as described elsewhere in this document.

[0326] The flame retardancy of samples 5 to 8 was then tested using DIN 53438 (June 1984). Samples 5 to 7 passed the test, but sample 8 failed. This indicates that the presence of fibrillated fibers in the tested amount in sample 8 adversely affected the flame retardancy of the nonwoven fiber web sample.

[0327] Although several embodiments of the invention have been described and illustrated herein, those skilled in the art will readily contemplate a variety of other methods and / or structures for performing the functions described herein and / or obtaining the results and / or one or more advantages described herein, and each of such variations and / or modifications is considered to be within the scope of the invention. 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 one or more specific applications using the teachings of the invention. Those skilled in the art will recognize, or can determine, many equivalents of the specific embodiments of the invention described herein using only conventional experimentation. Therefore, it should be understood that the foregoing embodiments are given by way of example only, and that the invention can be practiced in ways other than those specifically described and claimed within the scope of the appended claims and their equivalents. The invention relates to each individual feature, system, article of manufacture, material, kit, and / or method described herein. Furthermore, if such features, systems, articles, materials, kits, and / or methods are not inconsistent with each other, any combination of two or more such features, systems, articles, materials, kits, and / or methods is included within the scope of this invention.

[0328] All definitions defined and used in this document should be understood to take precedence over dictionary definitions, definitions in referenced files, and / or the general meaning of the defined terms.

[0329] Unless otherwise expressly stated, nouns without quantifiers as used herein, in the specification, and in the claims should be understood to mean "at least one".

[0330] The phrase “and / or” as used herein in the specification and claims should be understood to mean “any one or both” of the elements thus connected, i.e., elements that coexist in some cases and exist separately in others. Multiple elements listed with “and / or” should be understood in the same way, i.e., “one or more” of the elements thus connected. Other elements may optionally exist in addition to those specifically identified by the “and / or” clause, whether related to or unrelated to those specifically identified. Thus, as a non-limiting example, when used in conjunction with open-ended language such as “comprising,” reference to “A and / or B” may in one embodiment mean only A (optionally including elements other than B); in another embodiment, only B (optionally including elements other than A); in yet another embodiment, both A and B (optionally including other elements); and so on.

[0331] As used herein in the specification and claims, “or / or” should be understood to have the same meaning as “and / or” as defined above. For example, when items in a list are separated, “or / or” or “and / or” should be interpreted as inclusive, meaning that it includes multiple elements or at least one of the elements in the list, but also includes more than one, as well as optional additional items not listed. Only explicitly indicating the opposite terms, such as “only one of…” or “exactly one of…”, or when used in the claims, “consisting of…” will mean including multiple elements or exactly one of the elements in the list. Generally, the term “or / or” as used herein, when preceded by an exclusive term (e.g., “either one,” “one of…,” “only one of…,” or “exactly one of…”), should be understood only to indicate an exclusive substitution (i.e., “one or the other but not both”). “Substantially consisting of…” when used in the claims should have its general meaning as used in the field of patent law.

[0332] As used herein in the specification and in the claims, when referring to a list of one or more elements, the phrase "at least one" should be understood to mean at least one element selected from any one or more elements in the list, but does not necessarily include each and every element specifically listed in the list, and does not exclude any combination of elements in the list. This limitation also allows for the optional presence of elements other than those specifically identified in the list, whether related to or unrelated to those specifically identified 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, with no B (and optionally including elements other than B); in another embodiment, it may refer to at least one B, optionally including more than one B, with no A (and optionally including elements other than A); in yet another embodiment, it 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.

[0333] It should also be understood that, unless expressly stated to the contrary, in any method claimed herein that includes more than one step or action, the order of the steps or actions of the method is not necessarily limited to the order of the steps or actions of the method as described herein.

[0334] In the claims and in the above description, all conjunctions such as “comprising,” “including,” “with,” “having,” “containing,” “involving,” “holding,” “constituting,” etc., should be understood as open-ended, that is, as meaning including but not limited to. As described in Section 2111.03 of the U.S. Patent Examination Procedure Manual, only the conjunctions “constituting of” and “substantially consisting of” should be closed or semi-closed conjunctions, respectively.

Claims

1. A filter medium, comprising: Nonwoven fiber web and water-repellent additives; The nonwoven fiber web comprises fine microglass fibers, microglass fibers with medium diameter, coarse glass fibers, and fibrillated fibers; The average fiber diameter of the fine microglass fibers is less than or equal to 1 micrometer; The average fiber diameter of the microglass fibers with medium diameter is greater than 1 micrometer and less than or equal to 6 micrometers; The average fiber diameter of the coarse glass fiber is greater than 6 micrometers; and The nonwoven fiber web contains greater than 0% by weight and less than or equal to 20% by weight of the fibrillated fibers.

2. The filter medium according to claim 1, wherein the filter medium is free of perfluoroalkyl substances, polyfluoroalkyl substances and / or fluoropolymers.

3. The filter medium of claim 1 or 2, wherein the water-repellent additive comprises one or more water-repellent functional groups; each water-repellent functional group of the water-repellent additive is independently an alkyl group containing 3 or more carbon atoms, an alkenyl group containing 3 or more carbon atoms, and / or an alkyne group containing 3 or more carbon atoms; and each water-repellent functional group of the water-repellent additive is independently a side chain of a repeating unit of a polymer and / or bonded to silicon atoms and / or metal atoms.

4. The filter medium according to any one of the preceding claims, wherein the nonwoven fiber web comprises greater than 0% by weight and less than or equal to 15% by weight of the fibrillated fibers.

5. The filter medium according to any one of the preceding claims, wherein the nonwoven fiber web comprises greater than 0% by weight and less than or equal to 10% by weight of the fibrillated fibers.

6. The filter medium according to any one of the preceding claims, wherein the nonwoven fiber web comprises greater than 0% by weight and less than or equal to 5% by weight of the fibrillated fibers.

7. The filter medium according to any one of the preceding claims, wherein the nonwoven fiber web comprises greater than 0% by weight and less than or equal to 2% by weight of the fibrillated fibers.

8. The filter medium according to any one of the preceding claims, wherein the fibrillated fiber comprises lyocell fiber.

9. The filter medium according to any one of the preceding claims, wherein the fibrillated fibers comprise synthetic fibers.

10. The filter medium according to any one of the preceding claims, wherein the fibrillated fibers have a fibrillation level greater than or equal to 1 CSF and less than or equal to 1000 CSF.

11. The filter medium according to any one of the preceding claims, wherein the fibrillated fibers have a fibrillation level of greater than or equal to 10 CSF and less than or equal to 600 CSF.

12. The filter medium according to any one of the preceding claims, wherein the fibrillated fibers have a fibrillation level of greater than or equal to 200 CSF and less than or equal to 500 CSF.

13. The filter medium according to any one of the preceding claims, wherein the initial DOP γ of the filter medium is greater than or equal to 6 and less than or equal to 30.

14. The filter medium according to any one of the preceding claims, wherein the initial DOP γ of the filter medium is greater than or equal to 9 and less than or equal to 20.

15. The filter medium according to any one of the preceding claims, wherein the nonwoven fiber web comprises more than 0% by weight and less than or equal to 60% by weight of the coarse glass fiber.

16. The filter medium according to any one of the preceding claims, wherein the nonwoven fiber web comprises more than or equal to 5% by weight and less than or equal to 25% by weight of the coarse glass fiber.

17. The filter medium according to any one of the preceding claims, wherein the nonwoven fiber web comprises more than or equal to 10% by weight and less than or equal to 20% by weight of the coarse glass fiber.

18. The filter medium according to any one of the preceding claims, wherein the average diameter of the coarse glass fiber is less than or equal to 30 micrometers.

19. The filter medium according to any one of the preceding claims, wherein the average diameter of the coarse glass fiber is less than or equal to 14 micrometers.

20. The filter medium according to any one of the preceding claims, wherein the average diameter of the coarse glass fiber is less than or equal to 10 micrometers.

21. The filter medium according to any one of the preceding claims, wherein the coarse glass fiber comprises chopped filament glass fiber.

22. The filter medium according to any one of the preceding claims, wherein the chopped glass fibers comprise a first type of chopped glass fibers and a second type of chopped glass fibers.

23. The filter medium according to any one of the preceding claims, wherein the nonwoven fiber web comprises greater than 0% by weight and less than or equal to 95% by weight of the microglass fibers having a medium diameter.

24. The filter medium according to any one of the preceding claims, wherein the nonwoven fiber web comprises more than or equal to 20% by weight and less than or equal to 80% by weight of the microglass fibers having a medium diameter.

25. The filter medium according to any one of the preceding claims, wherein the nonwoven fiber web comprises more than or equal to 30% by weight and less than or equal to 70% by weight of the microglass fibers having a medium diameter.

26. The filter medium according to any one of the preceding claims, wherein the nonwoven fiber web comprises more than or equal to 30% by weight and less than or equal to 40% by weight of the microglass fibers having a medium diameter.

27. The filter medium according to any one of the preceding claims, wherein the nonwoven fiber web comprises 60% or more and 70% or more of the microglass fibers having a medium diameter.

28. The filter medium according to any one of the preceding claims, wherein the nonwoven fiber web comprises more than 0% by weight and less than or equal to 95% by weight of the fine microglass fibers.

29. The filter medium according to any one of the preceding claims, wherein the nonwoven fiber web comprises more than or equal to 5% by weight and less than or equal to 60% by weight of the fine microglass fibers.

30. The filter medium according to any one of the preceding claims, wherein the nonwoven fiber web comprises more than or equal to 10% by weight and less than or equal to 20% by weight of the fine microglass fibers.

31. The filter medium according to any one of the preceding claims, wherein the nonwoven fiber web comprises more than or equal to 40% by weight and less than or equal to 50% by weight of the fine microglass fibers.

32. The filter medium according to any one of the preceding claims, wherein the nonwoven fiber web further comprises a resin.

33. The filter medium according to any one of the preceding claims, wherein the nonwoven fiber web comprises more than 0% by weight and less than or equal to 50% by weight of the resin.

34. The filter medium according to any one of the preceding claims, wherein the nonwoven fiber web comprises more than 0% by weight and less than or equal to 10% by weight of the resin.

35. The filter medium according to any one of the preceding claims, wherein the nonwoven fiber web comprises more than or equal to 1% by weight and less than or equal to 5% by weight of the resin.

36. The filter medium according to any one of the preceding claims, wherein the resin comprises a first type of resin and a second type of resin.

37. The filter medium according to any one of the preceding claims, wherein the nonwoven fiber web comprises more than 0% by weight and less than 50% by weight of the resin of the first type.

38. The filter medium according to any one of the preceding claims, wherein the nonwoven fiber web comprises more than or equal to 0.5% by weight and less than or equal to 5% by weight of the resin of the first type.

39. The filter medium according to any one of the preceding claims, wherein the nonwoven fiber web comprises more than 0% by weight and less than 50% by weight of the resin of the second type.

40. The filter medium according to any one of the preceding claims, wherein the nonwoven fiber web comprises more than or equal to 0.5% by weight and less than or equal to 5% by weight of the resin of the second type.

41. The filter medium according to any one of the preceding claims, wherein the nonwoven fiber web comprises less than 2% by weight of synthetic fibers comprising poly(vinyl alcohol).

42. The filter medium according to any one of the preceding claims, wherein the nonwoven fiber web comprises less than or equal to 1% by weight of synthetic fibers comprising poly(vinyl alcohol).

43. The filter medium according to any one of the preceding claims, wherein the nonwoven fiber web comprises less than or equal to 0.5% by weight of synthetic fibers comprising poly(vinyl alcohol).

44. The filter medium according to any one of the preceding claims, wherein the nonwoven fiber web comprises less than or equal to 0.1% by weight of synthetic fibers comprising poly(vinyl alcohol).

45. The filter medium according to any one of the preceding claims, wherein the nonwoven fiber web does not contain synthetic fibers comprising poly(vinyl alcohol).

46. ​​The filter medium according to any one of the preceding claims, wherein the nonwoven fiber web comprises less than or equal to 3% by weight of bicomponent fibers.

47. The filter medium according to any one of the preceding claims, wherein the nonwoven fiber web comprises less than or equal to 0.5% by weight of bicomponent fibers.

48. The filter medium according to any one of the preceding claims, wherein the nonwoven fiber web comprises less than or equal to 0.1% by weight of bicomponent fibers.

49. The filter medium according to any one of the preceding claims, wherein the nonwoven fiber web does not contain bicomponent fibers.

50. The filter medium according to any one of the preceding claims, wherein the nonwoven fiber web comprises less than or equal to 5% by weight of synthetic fibers other than the fibrillated fibers.

51. The filter medium according to any one of the preceding claims, wherein the nonwoven fiber web comprises less than or equal to 1% by weight of synthetic fibers other than the fibrillated fibers.

52. The filter medium according to any one of the preceding claims, wherein the nonwoven fiber web does not contain any synthetic fibers other than the fibrillated fibers.

53. The filter medium according to any one of the preceding claims, wherein the nonwoven fiber web has a wet strength of 5 grams or more.

54. The filter medium according to any one of the preceding claims, wherein the nonwoven fiber web has a wet strength of less than or equal to 100 grams.

55. The filter medium according to any one of the preceding claims, wherein the nonwoven fiber web has an F1 and / or K1 rating as measured according to DIN 53438 (June 1984).

56. The filter medium according to any one of the preceding claims, wherein the water repellency of the filter medium is greater than or equal to 0.5 inches of H2O and less than or equal to 300 inches of H2O.

57. The filter medium according to any one of the preceding claims, wherein the water repellency of the filter medium is greater than or equal to 0.5 inches of H2O and less than or equal to 100 inches of H2O.

58. The filter medium according to any one of the preceding claims, wherein the AC FlexLight Weight of the nonwoven fiber web is greater than or equal to 1 cycle and less than or equal to 400 cycles.

59. The filter medium according to any one of the preceding claims, wherein the AC FlexLight Weight of the nonwoven fiber web is greater than or equal to 10 cycles and less than or equal to 70 cycles.

60. The filter medium according to any one of the preceding claims, wherein the filter medium comprises greater than 0% by weight and less than or equal to 50% by weight of the water-repellent additive.

61. A filter element comprising a filter medium according to any one of the preceding claims.

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