Mechanical and electrostatic filter media

Abstract

Filter media and filters, such as air filters, face masks, gas turbine and compressor intake filters, panel filters, and the like, are provided that capture submicron particles both by electrostatic forces and by utilizing nanoparticles within the filter media. The filtration media includes a substrate that includes fibers and nanoparticles disposed within the substrate. At least one of the fibers or nanoparticles is electrostatically charged. The electrostatic charge efficiently captures submicron particles at least during initial use of the filter. The nanoparticles ensure that high filter efficiency is maintained even after the electrostatic charge begins to decay over time. Furthermore, the bond between the fibers and the nanoparticles is enhanced by the electrostatic charge, allowing the nanoparticles to be deeply dispersed throughout the filter media.

Description

[Technical field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims the benefit of U.S. Provisional Patent Application No. 63 / 328,970, filed April 8, 2022, the entire disclosure of which is incorporated herein by reference for all purposes. This application is also related to commonly assigned, co-pending U.S. Provisional Patent Applications Nos. 63 / 328,983, 63 / 328,998, 63 / 328,959, 63 / 329,009, 63 / 329,018, 63 / 329,137, 63 / 329,146, 63 / 329,155, 63 / 329,158, 63 / 329,161, and 63 / 329,162, all filed on April 8, 2022, the entire disclosures of which are incorporated herein by reference for all purposes.

[0002] This description relates generally to filtration media and filters that include nanoparticles and electrostatic charges for both mechanical and electrostatic filtration of contaminants. [Background technology]

[0003] Nonwoven materials typically have a structure of individual fibers or threads interleaved rather than in a discernible fashion as in knitted or woven fabrics. Such nonwoven materials are used in many applications, such as household cleaning products, roofing and flooring products, automotive interiors and headliners, reusable bags, wallpaper, filtration devices, insulation, etc. Nonwoven materials are particularly useful for trapping contaminants in filtration devices because the fibers are extremely fine. The fibers of the filter media are measured in micrometers and can be formed by techniques such as spunbonding, meltblown, electrospinning, etc. The extremely fine fibers capture and trap contaminants within the filter media as fluid flows through it. There are two main types of filtration devices incorporating nonwoven materials: surface filters and depth filters. Surface filters, such as membranes and films, act as a barrier to contaminants, capturing them before they enter the media structure. Surface filters typically have submicron pore sizes and narrow pore size distributions. Surface filters tend to have relatively high particle capture efficiencies. However, surface filters also have relatively high pressure drop and low dust loading capacity. High pressure drop leads to reduced airflow through the filter. Low dust loading capacity significantly shortens the life of the filter. Therefore, surface filters have been used in a limited number of applications in the air filtration industry. Depth filters are commonly used in air filtration devices with medium to high efficiency, low pressure drop, and relatively high dust loading capacity. Conventional residential and commercial air filters, such as HEPA filters, are typically rated by the filter's ability to capture particles between about 0.3 and 10 microns. This rating is called the Minimum Efficiency Reporting Value, or MERV, and is established by the American Society of Heating, Refrigerating and Air Conditioning Engineers (ASHRAE). MERV ratings range from 1 to 16, with higher values ​​indicating greater efficiency in capturing a particular type of particle.

[0004] Contaminants come in a wide range of sizes. However, contaminants smaller than 1 micron are the most harmful particles to the human body and are relatively difficult to filter. For example, conventional mechanical air filters typically report a MERV rating of about 8 to 10 for nonwoven filtration materials. Thus, these filter media typically do not capture submicron particles such as viruses and other harmful pathogens. The filtration industry has focused on two different methods to capture these submicron particles: electrostatic forces and the use of nanoparticles in filter media. Electrostatic filters are formed by electrostatically charging fibers in a nonwoven material using known methods such as triboelectricity, corona discharge, hydrocharging, and electrospinning. Electrostatic filters are most effective at capturing submicron particles, being quite effective at capturing particles between 1-3 microns in diameter, and only marginally effective at capturing larger particles between 3-10 microns. Electrostatic fibers are commonly used to filter submicron contaminants such as viruses in numerous filtration applications such as face masks and high efficiency filters. One drawback of electrostatic filters is that the electrostatic charge decays over time and with use of the filter. This causes the filter's efficiency to decrease relatively quickly, shortening the filter's lifespan. For example, an electrostatic filter with an initial MERV rating of 13 may lose at least 2-3 points of its MERV rating after the electrostatic force decays. This can compromise the integrity of the filter and partially or completely inhibit its ability to capture submicron particles.

[0005] Another method for capturing sub-micron contaminants is to use nanoparticles in conjunction with fibers. Filtration systems may use filter media that include relatively large fibers with diameters measured in micrometers and relatively small nanoparticles. The nanoparticles increase the surface area within the media for capturing particles by reducing the overall fiber size within the media. The nanoparticles also tend to collapse onto each other, increasing the packing density within the filter media. It has been shown that even small amounts of nanometer-sized fibers formed in a layer on a microfiber material can improve the filtration properties of the material. The most common method for incorporating nanoparticles into filter media is to apply a thin layer of continuous nanofibers onto a nonwoven substrate by electrospinning. The nanoparticles typically extend horizontally or vertically to the plane of the bulk filter media layer, providing high-efficiency filtration of small particles in addition to the filtration of larger particles provided by coarse filter media. For example, U.S. Patent No. 6,743,273 discloses a filter medium in which a continuous nanofiber layer is deposited on the surface of a substrate. U.S. Patent No. 10,799,820 also discloses an air filtration medium with a continuous nanofiber layer on the surface of the filter medium. Existing filter media incorporating nanoparticles improves the relative efficiency of the filter, but the commercial applicability of the filters has been limited because the nanoparticles are generally dispersed on the surface of the nonwoven material, and the relatively thin layer of nanoparticles on the filter surface provides only limited particle filtration and has a relatively low dust retention capacity. There have been many attempts to incorporate nanomaterials into filtration media to improve overall filtration efficiency, but these attempts have been limited to so-called "wet-laid" methods. These wet-laid methods involve incorporating short-cut nanofibers into a liquid slurry and separating the entangled nanofibers with the aid of a surfactant. For example, U.S. Pat. No. 10,252,201 discloses filter media made with a mixture of short-cut nanofibers and short-cut coarse fibers formed by a wet-laid process. Similarly, U.S. Patent Application Publication No. 2021 / 0023813 discloses a method for producing a composite structure consisting of a continuous fiber nonwoven substrate with discontinuous fibers, such as carbon nanofibers. The method involves drawing a continuous fiber nonwoven substrate through a slurry of discontinuous fibers in which nanomaterials are embedded in the nonwoven substrate. While these structures have demonstrated improved efficiency, they suffer from other issues such as reduced lifespan and / or efficiency as the media is subjected to normal use conditions. Additionally, these wet laid processes have not been successful in incorporating the nanoparticles uniformly throughout the nonwoven material, resulting in the nanoparticles agglomerating within the material, which further reduces its efficiency and overall dust holding capacity.

[0006] What is needed, therefore, are improved nonwoven materials and filters containing such materials. It would be desirable to improve the efficiency of such filters in capturing contaminants, particularly submicron contaminants, without compromising other important properties of the filter, such as life, dust holding capacity, and pressure drop or air flow through the filter. Summary of the Invention

[0007] The following presents a simplified summary of the claimed subject matter in order to provide a basic understanding of some aspects of the claimed subject matter. This summary is not an extensive overview of the claimed subject matter, and is not intended to identify key or critical elements of the claimed subject matter or to delineate the scope of the claimed subject matter. Its sole purpose is to present some concepts of the claimed subject matter as a prelude to the more detailed description that is presented later. Filter media and filters, such as air filters, face masks, gas turbine and compressor intake filters, panel filters, etc., are provided that capture submicron particles using both electrostatic forces and the use of nanoparticles within the filter media. Systems and methods for manufacturing such filters are also provided.

[0008] In one embodiment, the filtration media includes a substrate comprising fibers and nanoparticles disposed within the substrate. At least one of the fibers or nanoparticles is electrostatically charged. The electrostatic charge efficiently captures submicron particles, at least during the initial use of the filter. The nanoparticles ensure that the high filter efficiency is maintained even after the electrostatic charge begins to decay over time. Furthermore, the bond between the fibers and the nanoparticles is enhanced by the electrostatic charge, allowing the nanoparticles to be deeply dispersed throughout the filter media. The fibers, nanoparticles, or both within the substrate can be electrostatically charged using known methods such as triboelectric, corona discharge, electrospinning, hydrocharging, charging bars, etc. To enhance particle removal using the triboelectric effect, nanoparticles can be selected with different triboelectric properties relative to the fibers. This enhances or creates a localized electric field gradient within the filter media, enhancing particle removal. The nanoparticles and coarse fibers can have different wetting properties.

[0009] In certain embodiments, the fibers are electrostatically charged so that mechanical filtration can be achieved by nanoparticles and electrostatic filtration can be achieved by electret substrates. The electrostatic or electret substrates can be high loft triboelectric filter media made by carding and needling. In one embodiment, the nanoparticles are preferably disposed in the substrate prior to needling, and then the electrostatic fibers and nanoparticles are needled together. In certain embodiments, the nanoparticles are dispersed "in depth" within the substrate. As used herein, the term "deep" means that the nanoparticles are dispersed beyond the first surface of the substrate, with at least a portion of the nanoparticles being disposed between the first surface and a second, opposing surface in the structure of the substrate or medium. In certain embodiments, the nanoparticles are dispersed throughout substantially the entire medium from the first surface to the opposing second surface. In other embodiments, the nanoparticles are dispersed throughout the portion from the first surface to a location between the first and second surfaces. In other embodiments, the nanoparticles are disposed in a density gradient from the first surface to the opposing second surface of the substrate. The density of the nanoparticles may be greater at either the first surface or the second surface. The nanoparticles increase the overall surface area within the filter media, which enhances filtration efficiency and allows for the capture of sub-micron contaminants without significantly compromising other factors through the filter, such as pressure drop (i.e., airflow). Additionally, the filters disclosed herein are able to withstand harsh conditions, which allows the filter to achieve the same level of filtration performance throughout its life, increasing the overall dust holding capacity and thus extending the life of the filter, especially when compared to filters that rely solely or primarily on electrostatic effects for increased efficiency. In certain embodiments, the fibers may have a linear density of greater than about 3 denier. Fibers in air filters typically have a linear density of about 3 denier or less to ensure that the fibers are small enough to capture contaminants that pass through the filter. Applicants have surprisingly found that the use of nanoparticles dispersed throughout the filter media allows the fibers to have a greater linear density, for example, greater than 3 denier. This is because the nanoparticles provide greater filtering capacity. In some cases, the fibers may have a linear density of greater than 3 denier, 5 denier or more, 6 denier or more, or even 7-10 denier. The substrate may be comprised of a medium such as a sheet, layer, film, apertured film, mesh, netting, etc. In certain embodiments, the substrate will comprise a nonwoven material having a structure of interleaved individual fibers or threads. Examples of suitable nonwoven materials include, but are not limited to, meltblown, spunbond, bonded carded, airlaid, co-formed, hydroentangled, etc. fibers, layers, or webs. In other embodiments, knitted or woven fabrics are contemplated as the substrate.

[0010] In some embodiments, the filter includes one or more support layers coupled to a filter media. The support layer and / or filter media may include nanoparticles dispersed deep within the layer(s). In some embodiments, a polymer layer, membrane or film is provided having nanoparticles disposed deep within the polymer layer and including one or more apertures for gas or liquid flow therethrough. In certain embodiments, the nanoparticles are isolated within the fluid and dispersed throughout the first surface of the substrate. The nanoparticles can be selected from the group consisting of carbon fibers, glass fibers, polypropylene fibers, nylon fibers, polylactic acid fibers, and combinations thereof. In certain embodiments, the filtration media further comprises a binder within the fibrous material that binds the nanoparticles to the fibers. The binder may comprise a variety of conventional materials, such as naturally-based materials, such as starch, dextrin, guar gum, or synthetic resins, such as EVA, PVA, PVOH, SBR, polyglycolide, etc. In some embodiments, the substrate comprises its own binder composition. In these embodiments, the binder or binding material may or may not be added to the substrate. In one such embodiment, the substrate comprises biocomponent fibers, one of the components comprising an outer sheath at least partially surrounding an inner core. In certain embodiments, the core is eccentric from the sheath, while in other embodiments, the core is concentric with the sheath.

[0011] The nanoparticles may comprise any suitable material, for example, glass, biosoluble glass, ceramic materials, acrylics, carbon, metals such as alumina, polymers (e.g., nylon, polyethylene terephthalate, etc.), polyvinyl chloride (PVC), polyolefins, polyacetals, polyesters, cellulose ethers, polyalkylene sulfides, poly(arylene oxides), polysulfones, modified polysulfone polymers and polyvinyl alcohols, polyamides, polystyrene, polyacrylonitrile, polyvinylidene chloride, polymethyl methacrylate, polyvinylidene fluoride, and any combination thereof. The fibers of the substrate can be made by any method including, but not limited to, airlaid, spinneret, gel spinning, melt spinning, wet spinning, dry spinning, islands in the sea staple or spunbond, segmented pie staple or spunbond, etc. The fibers contemplated can have a number of cross-section shapes including, but not limited to, round, kidney bean, dog bone, trefoil, barbell, bow tie, star, Y-shaped, etc. The fibers may be man-made or natural. Suitable materials for the fibers include, but are not limited to, polypropylene, polyester (PET), PEN polyester, PCT polyester, polypropylene, PBT polyester, co-polyamide, polyethylene, high density polyethylene ("HDPE"), LLDPE, cross-linked polyethylene, polycarbonate, polyacrylate, polyacrylonitrile, polyfumaronitrile, polystyrene, styrene maleic anhydride, polymethylpentene, cyclic olefin copolymers or fluorinated polymers, polytetrafluoroethylene, perfluorinated ethylene and hexafluoropropylene or copolymers with PVDF such as P(VDF-TrFE) or terpolymers such as P(VDF-TrFE-CFE), propylene, polyimides, polyetherketones, cellulose esters, nylons and polyamides, polymethacrylates, poly(methyl methacrylate), polyoxymethylene, polysulfonates, acrylics, styrenated acrylics, pre-oxidized acrylics, polyvinyl chloride ... acrylic, fluorinated acrylic, vinyl acetate, vinyl acrylic, ethylene vinyl acetate, styrene-butadiene, ethylene / vinyl chloride, vinyl acetate copolymer, latex, polyester copolymer, carboxylated styrene acrylic or vinyl acetate, epoxy, acrylic multipolymer, phenolic, polyurethane, cellulosic, styrene, or any combination thereof. Other conventional fiber materials are contemplated.

[0012] In another aspect, a method of making a filter media includes providing a substrate of fibers, electrostatically charging the fibers, and dispersing nanoparticles in the substrate. The electrostatically charged fibers effectively capture submicron particles, at least during the initial use of the filter. The nanoparticles ensure that high filter efficiency is maintained even after the electrostatic charge begins to decay over time. Furthermore, the bond between the fibers and the nanoparticles is enhanced by the electrostatic charge, allowing the nanoparticles to be deeply dispersed throughout the filter media. The fibers in the substrate can be electrostatically charged using known methods such as triboelectric methods, corona discharge, electrospinning, hydrocharging, charging bars, etc. In certain embodiments, the method corona charges the fibers. In other examples, the method includes tribocharging the fibers. In certain embodiments, the fibers are charged before the nanoparticles are dispersed in the substrate. In other embodiments, the nanoparticles are dispersed and captured in the substrate and then the fibers are electrostatically charged. In yet other embodiments, these processes can occur substantially simultaneously. In certain embodiments, the method includes electrospinning the fibers. In other examples, the method includes needling the fibers and nanoparticles together. The method may include carding the fibers. The method may include spunbonding the fibers. The method may include meltblowing the fibers. In certain embodiments, the method includes dispersing nanoparticles on a first surface of a substrate such that the nanoparticles penetrate at least the first surface of the substrate. The method can further include isolating individual nanoparticles within the fluid, the individual nanoparticles having at least one dimension less than 1 micron.

[0013] The method may further include isolating and / or isolating the nanoparticles in a gaseous medium, such as air, helium, nitrogen, oxygen, carbon dioxide, etc., and then dispersing the particles into a substrate via a suitable delivery mechanism, such as an air stream, aerosol, vaporizer, spray, etc. Isolating and / or isolating the nanoparticles in a gaseous medium and then dispersing the particles into a substrate or gas stream may allow the nanoparticles to be more uniformly distributed throughout the product. Additionally, the nanoparticles may be "deeply" dispersed or distributed within the product. Reference herein to desirable objects achieved by various embodiments of the present description is not meant to imply or suggest that any or all of those objects are present as essential features, either individually or collectively, in the most general embodiment of the description, or in any of the more specific embodiments. [Brief description of the drawings]

[0014] [Figure 1] FIG. 1 is a side view of a nonwoven material having nanoparticles dispersed within a portion of the material. [Diagram 2] FIG. 1 is a side view of a nonwoven material having nanoparticles dispersed throughout the material. [Diagram 3] FIG. 1 is a side view of a nonwoven material having nanoparticles dispersed in a gradient throughout the material. [Figure 4] 1 shows a dual layer filter media. [Figure 5A] 1 shows biocomponent fibers incorporated into a nonwoven material. [Figure 5B] 1 shows biocomponent fibers incorporated into a nonwoven material. [Figure 5C] 1 shows biocomponent fibers incorporated into a nonwoven material. [Figure 6] 1 shows a pleated nonwoven filter media. [Figure 7] A typical air filter is shown. [Figure 8] 1 shows a gas filter having first and second support membranes and a filter media. [Figure 9A] 1 shows an apertured film for use as a support membrane. [Figure 9B] 1 shows an apertured film for use as a support membrane. [Figure 10A] 1 illustrates an embodiment of an apertured film having nanoparticles incorporated within the film. [Figure 10B] 1 illustrates an embodiment of an apertured film having nanoparticles incorporated within the film. [Figure 10C] 1 illustrates an embodiment of an apertured film having nanoparticles incorporated within the film. [Figure 10D] 1 illustrates an embodiment of an apertured film having nanoparticles incorporated within the film. [Figure 10E] 1 illustrates an embodiment of an apertured film having nanoparticles incorporated within the film. [Figure 11] A gas filter is shown. [Figure 12]1 illustrates a schematic of a system for producing a nonwoven material within a substrate. [Figure 13] 1 illustrates a schematic of a system for converting clusters of nanofibers into individual nanoparticles. [Figure 14A] Photograph of a macrocluster of nanofibers. [Figure 14B] Photograph of small clusters of nanofibers. [Figure 14C] 1 is a photograph of individualized nanoparticles. [Figure 15] 14 shows an eductor for the system of FIG. 13; [Figure 16] 14 shows a reactor for the system of FIG. 13. [Figure 17] 1 illustrates another embodiment of a system for converting clusters of nanofibers into individual nanoparticles. [Figure 18] 1 illustrates a system for producing a dual layer nonwoven material. [Figure 19] 1 shows a nonwoven material with nanoparticles dispersed throughout the depth of the material. [Figure 20] 1 shows a nonwoven material with nanoparticles dispersed throughout the depth of the material, with a scrim layer covering the nanoparticles. [Figure 21] 1 shows a dual-layer nonwoven material with nanoparticles dispersed on the inner surface of the two layers. [Figure 22] 1 illustrates an alternative embodiment of a system for producing a nonwoven material in a fluid stream. [Figure 23A] 1 is a photograph of a nonwoven material without a binder. [Figure 23B] 1 is a photograph of a nonwoven material using a binder. [Figure 24A] Photograph of a nonwoven material with nanoparticles dispersed throughout the material in agglomerates or clusters. [Figure 24B] 1 is a photograph of a nonwoven material having nanoparticles substantially uniformly dispersed throughout the material. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] This description and the accompanying drawings illustrate exemplary embodiments and should not be taken as limiting, and the claims define the scope of this description, including equivalents. Various mechanical, compositional, structural, and operational changes, including equivalents, may be implemented without departing from the scope of this description and claims. In some cases, well-known structures and methods have not been shown or described in detail so as not to obscure the description. Like numbers in two or more drawings represent the same or similar elements. Furthermore, elements and related aspects thereof that are described in detail with reference to one embodiment may, whenever practical, be included in other embodiments that are not specifically shown or described. For example, even if an element is described in detail with reference to one embodiment and not described with reference to a second embodiment, the element may still be claimed to be included in the second embodiment. Furthermore, the depictions herein are for illustrative purposes only and do not necessarily reflect the actual shape, size, or dimensions of the system or illustrated components. As used in this specification and the appended claims, it should be noted that the singular forms "a," "an," and "the," as well as use of any singular form of any word, include plural references unless expressly and unambiguously limited to one reference. As used herein, the term "comprises" and grammatical variations thereof are intended to be open-ended, and the recitation of items in a list does not exclude other similar items that may be substituted for or added to the items in the list. Unless otherwise specified, any quantitative values ​​are approximate, whether or not preceded by words such as "about" or "approximately." The materials, methods, and examples described herein are illustrative only and are not intended to be limiting.

[0016] Nonwoven materials and products comprising nonwoven materials are provided, including substrates, sheets, layers, films, perforated films, meshes or other media, comprising fibers and nanoparticles attached to the fibers and incorporated into at least a portion of the substrate. As used herein, the term "nanoparticle" refers to any particle having a dimension of less than 1 micron in at least one axis or dimension. For example, a fiber having a diameter or width of less than 1 μm and a length of more than 1 μm is a nanoparticle as used herein. In certain embodiments, each individual nanoparticle can be a small particle ranging in size from about 1 to about 1000 nm, preferably from about 1 to about 650 nm. In a few particle size distribution, at least half of the particles can measure 100 nm or less in diameter. The majority of nanoparticles are typically composed of only a few hundred atoms. As the size of nanoparticles approaches the atomic scale, the material properties change. This is because the surface area to volume ratio increases, and as a result, the surface atoms of the material dominate the material performance. Because nanoparticles are so small in size, they have a very large surface area to volume ratio compared to bulk materials such as powders, plates, sheets, or larger fibers. This feature allows nanoparticles to have unexpected optical, physical, and chemical properties because they are small enough to confine electrons and produce quantum effects. In some embodiments, the nanoparticles comprise nanofibers that have at least one dimension less than 1 micron (i.e., diameter, width, height, etc., depending on the cross-sectional shape of the fiber). The nanofibers may have a continuous length, or the nanofibers may have discrete lengths, such as between 1 and 100,000 microns, preferably between about 100 and 10,000 microns.

[0017] The nonwoven substrates discussed herein may have a structure of individual fibers or threads that are interleaved, entangled, or bonded together. Nonwovens may include sheet or web structures that are mechanically, thermally, or chemically bonded by entangling fibers or filaments (and by perforating films). Nonwovens are substantially flat porous sheets made directly from separate fibers or from molten plastic or plastic films. Examples of suitable nonwoven materials include, but are not limited to, meltblown, spunbonded or spunlaced, thermally bonded, bonded carded, airlaid, wetlaid, co-formed, needle punched, stitched, hydroentangled, etc. fibers, layers, or webs. In certain embodiments, the substrate may include knitted and / or woven materials. Knitted materials may include any knit pattern suitable for the desired application. Knitted materials suitable for filter applications include weft knits, warp knits, knit mesh panels, compressed knit meshes, and the like. Woven materials suitable for filter applications include fibrous filter media such as monofilament fabrics, multifilament fabrics, nylon meshes, polyester meshes, polypropylene meshes, and the like. Woven fabrics may be used, for example, in mesh filter press fabrics, woven filter pads and other die cut pieces, centrifugal filter bags, liquid filter bags, dust collector bags, bed dryer bags, rotary drum filters, filter belts, leaf filters, roll media, and the like. In some embodiments, the nonwoven material may comprise a structure comprising intermingled or intertwined short-cut fibers and / or filaments. Short-cut fibers, as used herein, refer to fibers of finite length. Filaments, as used herein, refer to fibers having a substantially continuous length. In some embodiments, the substrate may comprise short-cut coarse, microfibers and / or fine fibers. As used herein, "fine fibers" refer to fibers having a diameter less than 1 micron, "coarse fibers" refer to fibers having a diameter greater than 10 microns, and microfibers are synthetic fibers having a diameter less than 10 microns.

[0018] In certain embodiments, the nanoparticles are "deeply" dispersed in the substrate. As used herein, the term "deeply" means that the nanoparticles are dispersed beyond a first surface of the substrate, with at least a portion of the nanoparticles being disposed between the first surface and a second, opposing surface in the internal structure of the substrate or medium. In certain embodiments, the nanoparticles are dispersed throughout substantially the entire medium from the first surface to the opposing second surface. In other embodiments, the nanoparticles are dispersed throughout the entire portion of the medium from the first surface to a location between the first surface and the second surface. In some embodiments, the nanoparticles are distributed three-dimensionally in space relative to the supporting fibers, which can increase the fiber surface area and microvolume within the nonwoven material. The three-dimensional distribution also provides resistance to complete blockage of certain portions of the nonwoven material, which is particularly useful in filter media, as it allows fluids (e.g., gases such as air) to pass through the filter, thereby reducing the overall pressure drop across the filter. In other embodiments, the nanoparticles are arranged in a density gradient through the thickness of the substrate, such that a higher density of nanoparticles is located near one surface than on the opposite surface, or a higher density of nanoparticles is located on the surface compared to the center of the substrate. The density gradient shown may be substantially linear, may decrease in a series of discrete steps, or the gradient may be random (i.e., an overall decrease in density that is not linear or step-wise). This density gradient provides a number of advantageous features for certain applications, such as filters (as described below).

[0019] The nanoparticles may comprise any suitable material, for example, glass, biosoluble glass, ceramic materials, acrylics, carbon, metals such as alumina, polymers (e.g., nylon, polyethylene terephthalate, etc.), polyvinyl chloride (PVC), polyolefins, polyacetals, polyesters, cellulose ethers, polyalkylene sulfides, poly(arylene oxides), polysulfones, modified polysulfone polymers and polyvinyl alcohols, polyamides, polystyrene, polyacrylonitrile, polyvinylidene chloride, polymethyl methacrylate, polyvinylidene fluoride, and any combination thereof. In some embodiments, nanoparticles may be produced as bicomponent segmented pie and islands-in-the-sea. The filaments are then drawn sufficiently to obtain submicron filaments. The continuous filament nanofibers are cut according to the desired length, preferably from about 100 to about 10,000 microns. In some embodiments, the nanoparticles are absorbents and adsorbents. In some embodiments, the nanoparticles are activated carbon fibers or activated carbon powder. In some embodiments, the nanoparticles are catalytic particles or catalytic fibers. In some embodiments, the nanoparticles can be obtained by feeding a nonwoven fabric of submicron fibers into a shredder or grinder or edge trimmer machine, with the bonded nonwoven fabric going in and the short cut fibers coming out. For example, low mass biocomponent meltblown or nano meltblown fabric can be fed into a shredder and submicron nanoparticles can be obtained.

[0020] In some embodiments, different nanoparticles may be mixed. For example, nanofibers and nanobeads can be mixed. Two types of nanofibers with different melting points can be mixed, so that the lower melting nanoparticles can act as binders for the higher melting nanofibers. Nanoparticles with different diameters and lengths can also be mixed. In some embodiments, the nanoparticles are selected from environmentally sustainable sources. The nanoparticles may compromise biosoluble glass nanofibers, biodegradable nanoparticles, compostable nanoparticles, or recyclable compositions. Different types of nanoparticles may be combined. Some of the nanoparticles may be functional nanoparticles. For example, functional nanoparticles may include activated carbon and / or antibacterial materials deposited on and / or attached to the fibers in the nonwoven material. This may improve the gas absorption efficiency and sterilization effect of the fibers. Furthermore, nonwoven products of microfiber nonwovens with glass and carbon nanoparticles deposited therein provide filtration and deodorization functions as filter media. In some embodiments, the nanoparticles are bonded to the fibers by mechanical entanglement. This mechanical bond can be supplemented with adhesives or binders, as described in more detail below. In certain embodiments, the nanoparticles are not crimped (i.e., do not have the large wavy, bent, spiral, coiled sawtooth, etc. shapes associated with nanoparticles in a relaxed state). In other embodiments, the nanoparticles can have a crimped structure at some discrete lengths. For example, when these crimped nanofibers having a discrete length are attached to the fiber, the nanofibers entangle among themselves and also firmly attach to, on and around the fiber to form the modified fiber. In other embodiments, the attachment of the nanofibers to the micron fiber is achieved by electrostatic attraction and / or van der Waals forces between the fiber and the nanoparticles. Filter media and filters, such as air filters, face masks, gas turbine and compressor intake filters, panel filters, and the like, are provided that include nanoparticles deeply dispersed within the filter media. In some embodiments, the filters include one or more support layers bonded to the filter media. The support layer and / or filter media may include nanoparticles deeply dispersed within the layer(s). In some embodiments, polymer layers, membranes, or films are provided that have nanoparticles deeply disposed within the polymer layer and include one or more apertures for gas or liquid flow therethrough. In other embodiments, the nonwoven material comprises a flexible surface layer for bandages, face masks, and the like. Systems, devices, and methods are provided herein for manufacturing nonwoven materials and nonwoven material-containing products (e.g., gas filters). Systems and methods are also provided for isolating individual nanoparticles in a gaseous medium (rather than a liquid), such as air, helium, nitrogen, oxygen, carbon dioxide, etc., which can be dispersed into another product, film, layer, or substrate via airflow, aerosol, vaporizer, spray, or other suitable delivery mechanism.

[0021] Although the following description is presented primarily with respect to nonwoven materials and filter media, it should be understood that the devices and methods disclosed herein can be readily adapted to a variety of other applications. For example, the nonwoven materials disclosed herein can be useful in household cleaning products, roofing and flooring products, automotive interiors and ceiling linings, reusable bags, wallpaper, filtration devices, insulation, etc. Additionally, the individual nanoparticles isolated and produced by the processes described herein can be utilized in various coatings, composites and / or additives, for example, polymers, food packaging, flame retardants, fuel cells, batteries, capacitors, nanoceramics, lighting, materials manufacturing, manufacturing methods, materials such as composites and cements, medical diagnostic applications, medical therapeutic devices or treatments, tissue engineering such as scaffolds for bone or tissue repair, drinking water, industrial process fluids, food and beverage products, pharmaceutical and biological agents, tissue imaging, medical therapeutic delivery, environmental applications such as biodegradable compounds, etc. A more complete description of products that may incorporate nanoparticles can be found in commonly assigned, co-pending U.S. Provisional Patent Applications Nos. 63 / 328,970, 63 / 328,959, 63 / 328,983, 63 / 328,998, 63 / 329,009, 63 / 329,018, 63 / 329,137, 63 / 329,146, 63 / 329,155, 63 / 329,158, 63 / 329,161, and 63 / 329,162, all of which were filed on April 8, 2022, the entire disclosures of which are incorporated herein by reference for all purposes.

[0022] FIG. 1 illustrates a nonwoven material or substrate 10 including a plurality of fibers 12 and nanoparticles 14. The substrate 10 has a first surface 16, a second surface 18 opposite the first surface 16, and a width or thickness defined between the first surface 16 and the second surface 18. The nanoparticles 14 are deposited in the substrate through the first surface 16. As illustrated, the nanoparticles 14 penetrate through the first surface 16 into the "depth" of the substrate 10 between the first and second surfaces 16, 18. In some embodiments, the nanoparticles 14 penetrate at least 25% of the width or thickness between the first and second surfaces 16, 18 from the first surface, or more preferably at least about 50% of the thickness. In other embodiments, the nanoparticles 14 penetrate substantially the entire substrate 10 from the first surface 16 to the second surface 18. The nanoparticles 14 preferably comprise individual nanoparticles that are broken down, separated and isolated from one another prior to dispersion into the substrate 10 (as shown in FIG. 24B). Thus, the nanoparticles 14 are not present in layers within the nonwoven product and do not have large aggregates or bundles of nanofibers (as shown in FIG. 24A). This results in greater dispersion of the nanoparticles throughout the substrate, which in some applications, such as gas filters, provides a more efficient filtration capacity for filtering out contaminants. Furthermore, this provides a nonwoven material with a greater area density or "add-on amount" in grams per square meter (gsm) of nanoparticles within the material. The term "add-on amount" is used herein to mean the area density (gsm) of material, fibers or particles within a thin layer, sheet or film of material. In certain embodiments, the nanoparticles have a density of about 0.1 g / m 2 ~about 20g / m 2 , preferably at least about 2.0 g / m 2 The specific add-on amount or areal density may vary depending on the application. For example, applicants have found that the higher the areal density or amount of add-on, the more efficient the nonwoven material is at filtering out contaminants. Thus, the specific add-on amount of nanoparticles may depend on the desired efficiency of the filter media.

[0023] FIG. 2 illustrates a nonwoven material or substrate 20 including a plurality of fibers 12 and nanoparticles 14. As illustrated, the nanoparticles 14 permeate the entire width of the substrate 20 from the first surface 16 to the second surface 18. As illustrated in FIG. 2, in certain embodiments, the nanoparticles 14 are dispersed substantially throughout the fibers 12 of the substrate. In certain embodiments, the density of nanoparticles located at the first surface 16 differs by less than about 50% from the density of nanoparticles dispersed within the central portion of the substrate 20 between the surfaces 16, 18. In some embodiments, the difference is less than 25%, and preferably less than 10%. In certain embodiments, the amount or number of individual nanoparticles dispersed within the central portion of the substrate 20 is at least about 50%, preferably at least about 75%, and more preferably at least about 90% of the amount of individual nanoparticles dispersed at or near the first surface 16. In other embodiments, the nanoparticles 14 are arranged in a density gradient from the first surface 16 to the second surface 18. For example, FIG. 3 shows a substrate 30 in which the nanoparticles 14 form a density gradient in which the nanoparticles 14 located near the first surface 16 are denser than the second surface 18. In certain embodiments, the density of the nanoparticles located at the first surface 16 is more than about 75% different from the density of the nanoparticles dispersed at the second surface 18. In some embodiments, the difference is more than 50%. In some embodiments, the difference is more than 25%. In certain embodiments, the amount or number of individual nanoparticles dispersed at or near the second surface 18 is less than about 50%, preferably less than about 25%, and more preferably less than about 10% of the amount of individual nanoparticles dispersed at or near the first surface 16.

[0024] 3 may be substantially linear from the first surface 16 to the second surface 18. Alternatively, the density of nanoparticles 14 may decrease in a series of discrete steps from the first surface 16 to the second surface 18, or the gradient may be random (i.e., an overall decrease in density that is not linear or step-wise). In other embodiments, nanoparticles may be added to the substrate from both the first and second surfaces 16, 18. In these embodiments, the area density or "add-on amount" at the first and second surfaces 16, 18 may be substantially equal to one another or may differ depending on the application. In these embodiments, the area density or "add-on amount" at the center of the substrate is lower than the surfaces 16, 18. For example, the area density at the center of the substrate may be about 75% of the area density at the surfaces 16, 18, or may be about 50%, 40%, or 25%. The distribution of nanoparticles through the thickness of the nonwoven material can be measured, for example, using imaging techniques. Using techniques such as electron microscopy, a close-up of the nonwoven product taken at a horizontal cross-section of the product at the center of the thickness of the product can be compared to images taken at the top or bottom of the product, or all three images can be compared to determine how much the amount of nanoparticles deposited varies. Computerized image analysis processes can be used. For example, in FIG. 3, one cross-section can be taken at line AA and one cross-section can be taken at BB. A top view of each cross-section can be taken with a microscope, such as an electron microscope, a scanning electron microscope, etc. For example, a top view image of the cross-section taken at cross-section AA can be compared to a top view image taken at cross-section BB. The number of microfibers, the number of nanoparticles, or both in samples of the same two-dimensional size can be evaluated and compared. Additionally, imaging techniques can be used for three-dimensional samples. These techniques can be used to evaluate properties such as fiber orientation. These techniques can be used to determine whether the nanoparticles are deposited deep into the substrate, across a substantial portion of the substrate, substantially throughout the entire depth, or within a portion of the substrate depth.

[0025] Contemplated substrate fibers can be made by any method, including, but not limited to, airlaid, spinneret, gel spinning, melt spinning, wet spinning, dry spinning, islands-in-the-sea staple or spunbond, segmented pie staple or spunbond, and the like. Such methods are described in U.S. Pat. Nos. 4,406,950, 6,338,814, 6,616,435, 6,861,142, 7,252,493, 7,300,272, 7,309,430, 7,422,071, 7,431,869, 7,504,348, 7,774,077, 9,522,357, 9,993,761, and U.S. Patent Application Publication No. 2009 / 266,759, the entire disclosures of which are incorporated herein by reference for all purposes. Contemplated fibers may have a number of cross-sectional shapes, including but not limited to round, kidney bean, dog bone, trefoil, barbell, bow tie, star, Y-shape, etc. These and / or other conventional shapes may be used with the embodiments to obtain desired performance characteristics. The fibers in the substrate remain connected to one another by thermal bonding, chemical bonding, interentanglement, the use of bonding agents such as adhesives, etc. The fibers may be man-made or natural. Suitable materials for the fibers include, but are not limited to, polypropylene, polyester (PET), PEN polyester, PCT polyester, polypropylene, PBT polyester, co-polyamide, polyethylene, high density polyethylene ("HDPE"), LLDPE, cross-linked polyethylene, polycarbonate, polyacrylate, polyacrylonitrile, polyfumaronitrile, polystyrene, styrene maleic anhydride, polymethylpentene, cyclic olefin-based copolymers or fluorinated polymers, polytetrafluoroethylene, perfluorinated ethylene and hexafluoropropylene or copolymers with PVDF such as P(VDF-TrFE) or P(VDF-TFE). terpolymers such as terpolymers such as ethylene glycol terpolymer (e.g., ethylene glycol-ethylene glycol-rFE-CFE), propylene, polyimides, polyetherketones, cellulose esters, nylons and polyamides, polymethacrylics, poly(methyl methacrylate), polyoxymethylene, polysulfonates, acrylics, styrenated acrylics, pre-oxidized acrylics, fluorinated acrylics, vinyl acetate, vinyl acrylics, ethylene vinyl acetate, styrene-butadiene, ethylene / vinyl chloride, vinyl acetate copolymers, latex, polyester copolymers, carboxylated styrene acrylics or vinyl acetates, epoxies, acrylic multipolymers, phenolics, polyurethanes, cellulose, styrenes, or any combination thereof. Other conventional fiber materials are contemplated. The fibers may include fibers of different sizes, generally with fibers having diameters ranging from about 1 to about 1000 microns and lengths ranging from about ½ to 3 inches. The fibers may be configured as a gradient density media with decreasing pore size from the top (upstream) to the bottom (downstream) surface of the filter to improve capture efficiency and dust holding capacity. This configuration also allows different amounts of nanoparticles to be distributed at different depths in the filter media. For example, the upstream side of the filter media may have the largest fiber size allowing for more voids and greater nanoparticle density, while the downstream side of the filter media may have smaller fiber sizes providing a lower density of nanoparticles. Alternatively, this configuration may be reversed to provide a greater density of nanoparticles in the downstream portion of the filter media. Fibers in the medium may remain connected to other fibers by thermal bonding, chemical bonding, or interentanglement. Bicomponent fibers, which are particularly useful for mechanical filtration, are formed by extruding two polymers from the same spinneret with both polymers contained within the same filament. Suitable materials for bicomponent fibers include, but are not limited to, polypropylene (PP) / polyethylene (PE), polyethylene terephthalate (PET) / polypropylene (PP), and the like.

[0026] In some embodiments, the substrate may comprise a "high loft" nonwoven material comprising spunbonded or air-through bonded carded nonwoven fibers. As used herein, the term "high loft" means that the volume of voids is greater than the total solids volume. In air-through bonded carded nonwoven fibers, the loft of the substrate may be controlled by various means known to those skilled in the art. For example, loft may be improved by applying less compressive force to the medium during bonding. In another example, high loft nonwoven materials may be produced using fibers with a greater thickness, such as greater than 3 denier, e.g., 5 denier or greater, 6 denier or greater (discussed in more detail below). In other embodiments, loft may be improved by using eccentric biocomponent fibers, as shown in FIG. 5C and discussed in more detail below. In certain embodiments, the fibers may include a silicone-based coating to improve the efficiency of the filter media in capturing contaminants, particularly those in the E2 and E3 particle group ranges. The silicone-based coating may include a reactive silicone macroemulsion. The silicone emulsion may include, for example, a dimethyl silicone emulsion, an amino-type silicone emulsion, an organofunctional silicone emulsion, a resin-type silicone emulsion, a film-forming silicone emulsion, and the like. In one embodiment, the reactive silicone macroemulsion includes an amino-functional polydimethylsiloxane and / or a polyethylene glycol monotridecyl ether. Suitable silicone coatings are described in U.S. Provisional Patent Application No. 63 / 406,686, assigned to the assignee of the present invention and filed on September 14, 2022, the entire disclosure of which is incorporated herein by reference.

[0027] The filtration media may include a charging additive to modify the triboelectric charging of the fibers and increase the stability and / or persistence of the triboelectric charging in the filter. This improves the overall filtration efficiency of the filter without compromising other important properties of the filter, such as life, dust holding capacity, and pressure drop or airflow through the filter. Suitable charging additives for triboelectric charging are described in U.S. Provisional Patent Application No. 63 / 410,731, assigned to the assignee of the present invention and filed on September 28, 2022, the entire disclosure of which is incorporated herein by reference for all purposes.

[0028] The fibers may have a thickness suitable for the application. In some embodiments, the fibers have at least one dimension in the range of about 1 to about 10,000 μm, or about 1 to about 1,000 μm, or about 10 to 100 μm. The thickness of the fibers may also be measured in denier, which is a measure of the linear mass density of the fiber. In some embodiments, the fibers may have a linear density of about 1 denier to about 10 denier. The nanoparticles are fibers with at least one dimension in the range of about 1 to about 1,000 nm, or about 1 to about 100 nm. The above dimensions of the fibers and nanoparticles may be diameter or width, depending on the shape of the fiber or nanoparticle. For gas filters, such as pleated or non-pleated air filters, the fibers may have a linear density ranging from about 1 denier to about 10 denier. The filter media may include fibers of the same or different linear densities. Fibers in air filters typically have a linear density of about 3 denier or less to ensure that the fibers are small enough to capture contaminants through the filter. Applicants have surprisingly found that the use of nanoparticles dispersed throughout the filter media allows the fibers to have a greater linear density, for example, greater than 3 denier. This is because the nanoparticles provide greater filtering capacity. In some cases, the fibers may have a linear density greater than 3 denier, 5 denier or greater, 6 denier or greater, or even 7-10 denier. Applicants have also found that in some applications, fibers having a greater linear density (e.g., greater than about 3 denier) than fibers used in conventional filters provide more open space or pores in the filter media, which allows for a greater density of nanoparticles to be dispersed therein. While this may seem counterintuitive to one of ordinary skill in the art, Applicants have found that a greater linear density of fibers incorporating nanoparticles actually improves the overall efficiency of the filter. In certain embodiments, the filter media may include at least two different fiber thicknesses or linear densities, providing at least two different layers within the same filter media. For example, in some cases, one portion of the filter media will include fibers with a linear density of more than 3 denier, such as 5 denier or more or 6 denier or more. Another portion of the filter media may include fibers with a more standard linear density of 3 denier or less. This dual-layer filter media results in a first filter portion that primarily filters contaminants with high-density nanoparticles in fibers with a larger thickness, and a second filter portion that filters contaminants with fibers with a lower linear density, but both portions may include nanoparticles dispersed throughout the fibers. In certain embodiments, the filter media may include three or more separate portions or layers with different denier fiber ranges within each portion.

[0029] FIG. 4 shows a dual layer filter media including a first substrate 40 having a first surface 42 and a second surface 44 opposite the first surface; and a second substrate 50 having a first surface 52 and a second surface 54 opposite the first surface. The second substrate 40 second surface 44 is bonded to the second substrate 54 by any method known to those skilled in the art. The first substrate 40 contains fibers 46 having a relatively low linear density, e.g., on the order of 3 denier or less. The second substrate 50 contains fibers 56 having a relatively high linear density, e.g., on the order of 3 denier or more, such as 5 denier, 6 denier or more. The second substrate 50 also includes discrete nanoparticles 58 dispersed and bonded throughout the fibers 56 and / or held by the second substrate 50. The first substrate 40 may or may not also include nanoparticles. The first substrate 40 is configured to filter contaminants primarily with the fibers 46, although as previously mentioned, the first substrate 40 may also include nanoparticles. The second substrate 50 is configured to filter contaminants with both the fibers 56 and the nanoparticles 58. In some embodiments, the substrate may compromise additives such as antimicrobial and / or antiviral compositions, e.g., organic compounds containing silver, zinc, copper, organosilicon, tributyltin, chlorine, bromine, or fluorine compounds.

[0030] The fibers may include biocomponent fibers that include two or more different fibers bonded together. The fibers may comprise the same material or different materials. 5A-5C show various examples of biocomponent fibers that can be used with the nonwoven materials disclosed herein. FIG. 5A shows a fiber 60 having a core fiber 62 and a surrounding sheath fiber 64. In this embodiment, the core 62 is substantially concentric with the sheath. FIG. 5B shows a biocomponent fiber 70 having first and second fibers 72, 74 arranged side-by-side with one another. FIG. 5C shows a biocomponent fiber 80 having a core fiber 82 and a sheath fiber 84. In this embodiment, the core 82 is off-center with respect to the longitudinal axis of the sheath 84, which increases the overall loft of the biocomponent fiber. Of course, other configurations are possible. For example, the core can have a shape other than circular, such as a dogbone shape, a square shape, a triangle, a diamond shape, etc. Alternatively, the fiber may comprise multiple cores or be divided into three, four, or more quadrants. In certain embodiments, the nonwoven material (i.e., fibers and / or nanoparticles) are electrostatically charged, so that, for example, contaminants are captured by both mechanical and electrostatic filtration. The bond between the fibers and the nanoparticles can also be enhanced by electrostatically charging the nanoparticles, the fibers, or both. For example, in certain embodiments, the fibers are electrostatically charged so that mechanical filtration can be achieved by nanoparticles and electrostatic filtration can be achieved by an electret substrate. The electrostatic or electret substrate can be a high loft triboelectric filter media made by carding and needling. In one embodiment, the nanoparticles are preferably placed into the substrate before needling, and then the electrostatic fibers and nanoparticles are needled together.

[0031] The substrate, the nanoparticles, or both can be electrostatically charged using known methods such as triboelectric methods, corona discharge, electrospinning, hydrocharging, charging bars, etc. Corona charging is suitable for charging monopolymer fibers or fiber blends, or fabrics. Tribocharging can be suitable for charging fibers with different electronegativities. Electrospinning combines polymer charging and fiber spinning in a one-step process. Suitable methods of triboelectric charging are described in U.S. Provisional Patent Application No. 63 / 410,729, filed Sep. 28, 2022, assigned to the assignee of the present invention, and U.S. Patent No. 9,074,301, the entire disclosures of which are incorporated herein by reference for all purposes. To enhance particle removal using the triboelectric effect, nanoparticles can be selected that have different triboelectric properties relative to the fibers. In this way, the nanoparticles produced are formed in an electric field and are less susceptible to chemical contamination that may weaken the triboelectric effect. Nanoparticles that have different adsorption or surface charge properties than the coarse fibers can also be used, for example, in oil or water filtration. This difference can be used to enhance or create local electric field gradients within the filter media to enhance particle removal. The nanoparticles and the coarse fibers can have different wetting properties.

[0032] The nonwoven material may include a binding agent or binding material, such as an adhesive or binder, to facilitate bonding between fibers and / or retention of the nanoparticles in the substrate so that they adhere to or are otherwise held to the fibers to form a stable matrix within the substrate. The binding agent or binding material is preferably present in a relatively small amount to bind the individual nanoparticles to the fibers throughout the substrate. Binders can include a variety of conventional materials, such as naturally-based materials such as starch, dextrin, guar gum, etc., or synthetic resins such as EVA, PVA, PVOH, SBR, polyglycolide, etc. In certain embodiments, solvent-based adhesives are used where bonding occurs upon solvent evaporation. In one preferred embodiment, the binder or binding material comprises dextrin. In yet another embodiment, the binder comprises a composition of various substances such as water, 2-hexoxyethanol, isopropanolamine, sodium dodecylbenzenesulfonate, lauramine oxide, and ammonium hydroxide. In yet another embodiment, the binder comprises at least PVOH. The binder can be a solution, emulsion, suspension, hot melt, curable, neat, and / or combination. In some embodiments, an adhesive resin is used, which may be crosslinked after coating the adhesive onto the substrate. Adhesion (water / solvent resistance) may be promoted by self-crosslinking when the solvent in the adhesive formulation evaporates, or by thermal activation during the drying process. For certain adhesives, crosslinking may be achieved by high energy wavelengths of electromagnetic radiation, including but not limited to RF, UV, e-beam. The amount of adhesive can be controlled by adjusting the nozzle size of the spray coater 140 or by controlling the flow rate of the adhesive composition. The bonding agent may be applied using methods such as spray nozzles, dip coating, etc. In some embodiments, the binder or bonding material may include a surfactant to reduce the surface or interfacial tension of the binder, thereby increasing its dispersion and wetting properties and allowing the binder to more easily penetrate deeper into the substrate.Suitable surfactants for use with the adhesives disclosed herein include nonionic, anionic, cationic and amphoteric surfactants, such as sodium stearate, 4-(5-dodecyl)benzenesulfonate, sodium dodecylbenzenesulfonate wetting agent, docusate (sodium dioctyl sulfosuccinate), alkyl ether phosphates, benzalkonium chloride (BAC), perfluorooctane sulfonate (PFOS), and the like. In some embodiments, the substrate includes its own binder composition. In these embodiments, a binding agent or material may or may not be added to the substrate. In one such embodiment, the substrate includes biocomponent fibers, one of the components including an outer sheath at least partially surrounding an inner core (see Figures 5A and 5C). The sheath may comprise a material that bonds to the nanoparticles. For example, the sheath may comprise a material that becomes sticky and / or fluid when heated and / or dried. In the heating / drying step (described below), the sheath portion of the fiber is heated to its melting point and becomes sticky and / or fluid, resulting in bonding the nanoparticles to the substrate. In a preferred embodiment, bonding and drying occur simultaneously.

[0033] Figure 23A is a magnified image of a nonwoven product having nanoparticles deposited therein without the use of a binder material. Figure 23B is a magnified image of a nonwoven product having nanoparticles attached to the fibers using a binder material of dextrin and water. As shown, the nanoparticles adhere more uniformly to the fibers with the use of a binder. The examples of Figures 23A and 23B used a substrate having bicomponent microfibers with an inner portion being polyester and an outer portion being high density polyethylene ("HDPE"). Figure 23A shows a microfiber nonwoven product having a bicomponent microfiber substrate where biosoluble glass nanofibers are deposited in a layer on only the surface of the substrate, relying on electrostatic forces to retain the nanofibers. Nanofiber clumping and loss of nanofiber retention can be seen in Figure 23A. The substrate can be manufactured using meltblown, spunbond, or other methods described herein. In the example of FIG. 23B, a binder material was used. The substrate was sprayed with a mixture of dextrin and water, and the nanoparticles were applied to the substrate with greater uniformity and greater nanofiber retention. In further examples, any of the binder materials disclosed herein can be used. Additionally, nanoparticles of biosoluble glass are deposited deep into the substrate. In this example, the bicomponent microfiber substrate itself has a MERV rating of 4-10, which can be achieved using any of the methods described herein. In one example, a microfiber substrate with an initial MERV of 8 was used to produce a nonwoven product with a MERV of 13 for nanoparticles deposited deep into the substrate and carrying a static charge. In another example, a microfiber substrate with an initial MERV of 6 was used to produce a nonwoven product with a MERV of 15. The substrate is provided on a roll, and the nonwoven product can be produced on a commercial scale in a roll-to-roll continuous process, such as any of the processes and methods described herein. In one example, the roll-to-roll process was operated at 30 feet per minute.

[0034] In certain embodiments, the nonwoven materials described herein may be included as part of a filter device that captures or absorbs contaminants, such as liquid filters, gas filters for home and commercial air filtration, face coverings such as surgical masks, etc. The filter device may be a mechanical filter, an absorption filter, a sequestration filter, an ion exchange filter, a reverse osmosis filter, a surface filter, a depth filter, etc., and may be designed to remove many different types of contaminants from air, water, etc. In one such embodiment, the nonwoven material is incorporated into an air filter that removes particles and contaminants from the air, such as a HEPA filter (i.e., pleated mechanical air filter), UV light filter, electrostatic filter, washable filter, media filter, spun glass filter, pleated or non-pleated air filter, activated carbon filter, pocket filter, V-bank compact filter, filter sheet, flat cell filter, filter cartridge, etc. The nonwoven material may comprise a filter medium for air filtration, may be supported by a support layer, a scrim layer, or may be included in other layers or materials. Applicants have discovered that by incorporating nanoparticles deeply into the nonwoven material as described herein, the efficiency of the air filter is substantially increased without compromising other factors such as pressure drop (i.e., air flow) through the filter. Furthermore, these materials increase the overall dust holding capacity, particularly compared to filters that rely solely or primarily on electrostatic effects for increased efficiency, thereby increasing the life of the filter. Conventional home and commercial air filters, such as HEPA filters, are typically rated by the filter's ability to capture particles between about 0.3 and 10 microns. This rating, called the Minimum Efficiency Reporting Value or MERV, is established by the American Society of Heating, Refrigerating and Air Conditioning Engineers (ASHRAE). MERV ratings range from 1 to 16, with higher ratings indicating greater efficiency in capturing a particular type of particle. Conventional mechanical air filters typically report a MERV rating of about 8 for nonwoven filtration materials. Air filters are typically rated based on their initial efficiency (i.e., the efficiency of the air filter before use) and their efficiency over time and use. The latter efficiency is typically tested by a conditioning procedure called ASHRAE Standard 52.2 Appendix J. The air filters provided herein have an initial MERV rating of greater than about 10 and a pressure drop of less than about 0.5 inches of water. In some cases, the initial MERV rating is about 11 and a pressure drop of about 0.17 inches of water or less, or about 13 and a pressure drop of about 0.36 inches of water or less, or about 14 and a pressure drop of about 0.5 inches of water or less. The gas filters provided herein have a MERV rating of 10 or greater after the gas filters are conditioned to ASHRAE Standard 52.2 Appendix J. In some embodiments, the MERV rating is 13 or greater after the gas filters are conditioned to ASHRAE Standard 52.2, ISO Standard 16890, or any other industry accepted standard.

[0035] The MERV ratings of the nonwoven filter media described herein will vary based on many factors, including the type and size of fibers used in the filter media, the density of individual nanoparticles within the filter media, the width of the filter media, and the number and size of pleats (if present). MERV ratings can be measured for sheets of the nonwoven product as well as for nonwoven products formed as pleated filter media, and the pressure drop of each can vary. Similarly, the pressure drop across the filter media will also depend on many factors, including those mentioned above. One factor that affects both MERV rating and pressure drop is the density or add-on amount of nanoparticles in the substrate relative to the density of fibers in the substrate. Applicants have discovered that the lower the ratio between substrate density and nanoparticle density, the higher the MERV rating and the higher the pressure drop of the filter. In certain embodiments, the filter media described herein have a MERV rating of about 0.1 g / m 2 ~about 20g / m 2 , preferably at least about 2 g / m 2 has a nanoparticle areal density of In some cases, the density of the nanoparticles also depends on the density of the actual filter media (i.e., the density of the coarse fibers). As detailed below with reference to Table 2, a density ratio (substrate gsm divided by add-on nanoparticle gsm) of about 67 results in a pressure drop of about 0.14 inches of water column, giving an initial MERV rating of 10. A density ratio of about 33.4 raised the MERV rating to 10, but only increased the pressure drop to about 0.17. A density ratio of about 22.3 raised the initial MERV rating to about 12, giving a pressure drop of about 0.24 inches of water column. Thus, the efficiency or MERV rating of a filter may be increased with a higher nanoparticle add-on amount. In particular, Applicant has determined that the nanoparticle add-on amount is, for example, at least 2 g / m 2 I have found that with an add-on amount of 4 or 6 g / m, I can get a filter with a MERV rating of about 10. 2 This results in filters with MERV ratings of approximately 12 and 13, respectively. 2 If this is the case, you will get a filter with a MERV rating of 15 or higher. Applicants have also discovered that including fibers with greater thickness or linear density can result in larger pore size and, therefore, larger pore volume, which can result in a higher density of nanoparticles within the substrate. This results in an increased MERV rating and pressure drop (as discussed below with reference to Table 2). For example, Applicants have been able to produce air filters with a MERV rating of 14 and a pressure drop of 0.5 inches of water using 5 denier biocomponent fibers. Similarly, Applicants have been able to produce filters with a MERV rating of 13 and a pressure drop of only about 0.29 inches of water using 5 denier biocomponent fibers.

[0036] An example of a pleated filter media 90 is shown in FIG. 6. The filter 90 can include about 0-10 pleats per inch depending on the application. The filter media can be mounted on a cardboard or metal frame for use as an easily replaceable filter product (FIG. 7). As shown, a gas filter 94 was fabricated from the nonwoven materials described herein. As shown, the filter 94 includes a pleated nonwoven filter media 96 and a support layer 98 that provides rigidity and structure to the filter media 96.

[0037] 11 shows a gas filter 109 made with the nonwoven materials described herein. The gas filter 109 includes a nonwoven substrate having fibers and nanoparticles dispersed deep within the substrate. The substrate can then be rolled into a suitable shape, such as a cylinder, cone, etc., for use in gas turbine and compressor intake filters, panel filters, and other applications. Other types of filters that may be developed using the nonwoven materials disclosed herein include conical filter cartridges, square end cap filter cartridges, pocket filters, V-bank compact filters, panel filters, flat cell filters, pleated or non-pleated bag cartridge filters, and the like. The nonwoven products disclosed herein may be used in medical masks or other medical applications such as ventilator cartridges. Medical masks are designed to protect medical personnel and / or patients from substances such as microorganisms. For example, medical masks can block bacteria, which may have dimensions of, for example, about 3 microns, as well as viruses, which may have dimensions of, for example, about 0.1 microns. The masks are made using nonwoven materials in multiple layers and have structures such as ear loops, ties, etc., for attaching the mask to an individual's face. Wires may be incorporated into at least the upper portion of the mask to allow that portion to conform to the person's face. The masks may include a rigid polymer structure designed to hold the multi-layer nonwoven material in front of the person's face. In one example, the mask has three layers. The outer and inner layers include nonwoven materials such as spunbond polypropylene that provide breathability, although any of the materials mentioned herein may be used. The middle layer is disposed between the inner and outer layers and has a microfiber substrate with nanoparticles deposited deep in the substrate to provide an initial MERV of greater than 8, preferably greater than 10 MERV, and more preferably a MERV of 13 or greater. For breathability, the mask should have a pressure drop of 3-6 mm water column, more preferably 4 mm water column. It is desirable for the mask to have an efficiency of about 95%. Other examples of masks have four or more layers. Multiple layers of nonwoven products can be combined into one mask. In certain embodiments, the nonwoven material may be included in a thin film or layer that includes apertures, pores, or perforations. The apertures may be embossed with a pattern (circles, diamonds, hexagons, ovals, triangles, rectangles, etc.) and then stretched until the apertures are formed in the thinned areas caused by the embossing. Such apertured substrates can be formed from many polymers, such as polypropylene, polyethylene, high density polyethylene ("HDPE"). For example, the polymer layer may include an extruded film. Apertured films are commercially available and are sold under the trademark Delnet®. The substrate is provided in a roll and the nanofibers are deposited on the substrate in a roll-to-roll process. Figures 10A-10E show examples of apertured films that may be formed by the methods described herein. In another embodiment, a gas filter includes a filter media and a substantially rigid support layer bonded to the filter media, the support layer including fibers and nanoparticles dispersed deeply within the layer, the nanoparticles configured to filter contaminants passing through the support layer.

[0038] 8, a composite filter element 814 includes an inner filter substrate 812 and one or more filter support members or membranes 810. The support member 810 may be formed from a thermoplastic polymeric material such as an extruded sheet of polymer, e.g., polypropylene film, high density polyethylene film, polylactic acid film, or an extrudable fluoroplastic material, and in an embodiment may be formed from a perfluoroalkane (PFA) copolymer formed from the comonomers polytetrafluoroethylene and perfluoroalkyl vinyl ether. However, other polymeric materials such as fluoroplastics, e.g., ethylene chlorotrifluorethyle (ECTFE); ethylene tetrafluoroethylene (ETFE) of polyvinylidene fluoride (PVDF), may also be used. In certain embodiments, as described above, support membrane 810 includes individual nanoparticles dispersed deep within membrane 810. The nanoparticles enable the support membrane to filter at least a portion of the contaminants that pass through filter membrane 814 (i.e., in addition to the filtration provided by inner filter substrate 812). In other embodiments, filter substrate 812 and / or support membrane 810 include such nanoparticles. Fluoroplastic materials such as PFA are highly desirable for use in filters intended for cleaning semiconductor components and other environments where extreme cleanliness is required and the potential for contamination is minimized. Such support membranes are designed to both direct the fluid to be filtered along their surface and also direct the fluid through their structure into the underlying filter substrate to remove undesirable particles from the filtrate.

[0039] As shown in Figures 9A and 9B, the support film 810 may include a plurality of apertures 828. The apertures are preferably circular, although it will be appreciated that other shapes are possible, such as square, rectangular, triangular, etc. The substrate may be wound into a roll and then unwound and directed through a punch press to form the desired, predetermined pattern of apertures 828 running through the Z direction (Figure 9A). Alternatively, the sheet may be set and then directed through a punch press for continuous operation, where the predetermined pattern of apertures 828 is formed. Referring to FIG. 9B, after apertures are drilled, the filter support member can be stretched in the machine direction, as indicated by double arrow 940, to lengthen apertures 828 and provide a larger open area for the passage of fluid being filtered by filter media or substrate 812. In another embodiment, the support membrane 810 may be porous (i.e., rather than or in addition to the apertures 828). In this embodiment, additional fluid flow can be achieved by the substantially porous support membrane. In an exemplary embodiment, the support membrane has a porosity value of at least 0.5 or 50%, preferably at least 0.8 or 80%, more preferably about 0.86 or 86%. The porosity value is defined as the fraction of non-solid or pore volume of the total volume of the material. A more complete description of such composite filter media can be found in PCT Application No. US2020 / 040941, the entire disclosure of which is incorporated herein by reference for all purposes. The filter support membrane of the present invention may be prepared by any method known to those skilled in the art. In one example shown in Figures 9A and 9B, the support membrane includes ribs. For example, the support membrane may be made by extruding a polymeric material to form a sheet and then passing the sheet through a nip area provided by opposing rollers, at least one of which has an outer surface with countersink grooves. The countersink grooves of one roller are aligned with the outer surface or countersink grooves of the other roller in the nip area to form a ribbed sheet with ribs rising from at least one surface of the sheet. Alternatively, the ribs may be formed by an extrusion process or known embossing methods. Once the ribs are formed, the support membrane may be wound into a roll and then unwound and oriented through a press to form apertures through its Z-direction in a desired, predetermined pattern. Alternatively, as best shown in Figure 9A, the support membrane may be set and then directed through a punch press for a continuous operation to form a predetermined pattern of apertures. Optionally, the support membrane can be stretched in the machine direction (indicated by the double arrow in FIG. 9B) to enlarge the apertures, e.g., to provide a larger open area for the passage of fluid to be filtered by the filter layer or substrate.

[0040] 12 illustrates generally an overall system 110 for producing nonwoven materials and other materials as described above. As shown, the system 110 includes a feeder 120 for advancing a material, such as a nonwoven fibrous substrate 130, through a manufacturing process. The system 100 further includes a coater 140, a fiberization system 150, and a heating and / or drying device 160. In certain embodiments, the system 100 further includes a vacuum or other negative pressure source 170 beneath the substrate 130 opposite the fiberization system 150. In one embodiment, the feeder 120 includes a winder 122 at the downstream end of the process and an unwinder 124 at the upstream end that continuously winds the substrate 130 through the system 100. In certain embodiments, the feeder 120 may further include a support surface (not shown) extending between the winders to support the substrate 130 as it moves downstream through the system 100. In other embodiments, the substrate is unwound directly from the unwinder 124 to the winder 122 without a separate support surface. The coater 140 is configured to spray droplets of a bonding agent or material, such as an adhesive or binder, onto the substrate 130 to allow the nanoparticles to bond to the fibers in the substrate 130 and form a stable matrix. The bonding agent is preferably present in a relatively small amount to bond the individual nanoparticles to the fibers throughout the substrate 130. In a preferred embodiment, the coater 140 includes a spray nozzle sized to produce adhesive droplets having a diameter of about 20-30 microns to increase the penetration depth of the adhesive into the substrate 130. Of course, the droplet size can be affected by numerous other parameters, such as air pressure, volume of air, air temperature, humidity, spray horn design, adhesive rheology / viscosity, carrier, etc. Of course, it will be appreciated that coating the substrate with the binder or binding material may be accomplished by other coating methods, including ultrasonic spraying, dip coating, spin coating, gravure coating, kiss roll coating, screen coating, powder coating, electrostatic, sputter coating, and the like.

[0041] As noted above, binders can include a variety of conventional materials, such as naturally-based materials such as starch, dextrin, guar gum, etc., or synthetic resins such as EVA, PVA, PVOH, SBR, etc. In certain embodiments, solvent-based adhesives are used where bonding occurs upon solvent evaporation. In one preferred embodiment, the binder comprises dextrin. In another embodiment, the binder comprises a composition of various substances such as water, 2-hexoxyethanol, isopropanolamine, sodium dodecylbenzenesulfonate, lauramine oxide, and ammonium hydroxide. In yet another embodiment, the binder comprises PVOH. The binder can be a solution, emulsion, suspension, hot melt, curable, neat, and / or combination. In some embodiments, an adhesive resin is used, which may be crosslinked after coating the adhesive onto the substrate 130. Adhesion (water / solvent resistance) may be promoted by self-crosslinking when the solvent in the adhesive formulation evaporates or by thermal activation during the drying process. For certain adhesives, crosslinking may be achieved by high energy wavelengths of electromagnetic radiation, including but not limited to RF, UV, e-beam. The amount of adhesive can be controlled by adjusting the nozzle size of the spray coater 140 or by controlling the flow rate of the adhesive composition. In some embodiments, the binder may include a surfactant to reduce the surface or interfacial tension of the binder, thereby increasing its dispersion and wetting properties and allowing the binder to penetrate deeper into the substrate more easily.Suitable surfactants for use with the binders disclosed herein include nonionic, anionic, cationic and amphoteric surfactants, such as sodium stearate, 4-(5-dodecyl)benzenesulfonate, sodium dodecylbenzenesulfonate wetting agent, docusate (sodium dioctyl sulfosuccinate), alkyl ether phosphate, benzalkonium chloride (BAC), perfluorooctane sulfonate (PFOS), and the like.

[0042] In some embodiments, the spray coater 140 is located upstream of the fiberization system 150 so that the binder is sprayed before the nanoparticles are deposited. In other embodiments, the spray coater 140 is located downstream of the fiberization system 150 so that the binder can be sprayed after nanoparticle deposition. In other embodiments, the system 100 includes two types of spray coating; one located upstream of the fiberization system 150 and one downstream of the fiberization system 150 that coats the substrate 130 with a secondary binder after nanoparticle deposition (not shown). In some embodiments, there are multiple nozzle heads in each spray coater 140. The nozzle heads may be arranged in series, for example, to improve uniformity or to increase the spray width of the fibers. Alternatively, the nozzle heads may be positioned in parallel, i.e., across the entire width of the substrate, to ensure that the binder is coated across the entire width of the substrate. In a preferred embodiment, a negative pressure or vacuum source (not shown) is positioned underneath the substrate 130 opposite the spray coater 140 to enhance penetration depth and uniformity of the binder. The negative pressure source can be any suitable suction device that draws the binder through the substrate, such as a suction pump or the like.

[0043] In some embodiments, the substrate includes its own binder composition. In these embodiments, the binder may or may not be added to the substrate. In one such embodiment, the substrate includes a biocomponent fiber 600, one of the components of which includes an outer sheath 64 at least partially surrounding an inner core 62. In certain embodiments, the sheath 64 and the core 62 may be substantially concentric with one another (FIG. 5A). In other embodiments, the core 84 may be eccentric from the sheath 82 (FIG. 5C). In other embodiments, the core 72 and the sheath 74 are aligned with one another (FIG. 5B). Of course, other configurations are possible. For example, the core 184 may have a shape other than circular, such as a dogbone shape, a square shape, a triangle, a diamond shape, etc. Alternatively, the fiber 180 may include multiple cores or may be divided into three, four, or more quadrants. The sheath 64 may include a material that bonds to the nanoparticles. For example, the sheath 64 may include a material that becomes sticky and / or fluid when heated and / or dried. During the heating / drying process, the sheath 64 portion of the fiber is heated to its melting point and becomes sticky and / or fluid, resulting in bonding the nanoparticles to the substrate. In a preferred embodiment, bonding and drying occur simultaneously in the drying device 160.

[0044] FIG 13 shows a schematic of a fiberization system 150 for converting groups of nanofibers into individual nanoparticles. The term "fiberization" as used herein means converting (e.g., opening, separating, isolating, and / or individualizing) clusters, agglomerates, and the like, of nanoparticles (which may or may not be entangled with one another) into individual nanoparticles having at least one dimension less than 1 micron. FIGs 14A-14C show examples of macroclusters of entangled nanofibers (FIG 14A), small clusters of entangled nanofibers (FIG 14B), and individual nanoparticles (FIG 14C). As shown, the fiberization system 150 includes a feeder 200, such as a hopper, for introducing larger or macro-clusters / agglomerates of nanoparticles (see FIG. 14A) into the system 150. The feeder 200 may comprise any suitable hopper device known to those skilled in the art, and is preferably configured to introduce macro-clusters of particles into the process at a specific rate that depends on the downstream fiberization rate. The nanoparticles may be introduced continuously at a specified rate or at intervals at a specific rate. The macro-clusters of bundled nanoparticles may be broken down prior to introduction into the feeder 200. It should be appreciated that the nanoparticles can be introduced to the fiberization device 150 in many different forms. For example, raw nanofibers can be produced as long, discrete fibers. In this form, the nanofibers can be cut to obtain a desired length to diameter ratio. The system 150 further includes a separator 210, such as a blender, to separate or break down macroclusters / agglomerates of nanoparticles into smaller clusters / agglomerates of nanoparticles (see FIG. 14B). The feeder 200 transfers the nanofibers to the separator 210 in a steady, continuous manner by any mechanical means. The rate of transfer depends on a variety of factors, such as the speed of the substrate 130 along the feeder 120, the rate of fiberization of the nanoparticles, etc. By controlling the amount of nanoparticles that fall into the separator 210, the amount of nanoparticles that are dispersed into the substrate can be controlled to create a continuous manufacturing process. In one embodiment, the separator 210 includes a housing 212 having a first opening 214 connected to the feeder 200 and a second opening 216 connected to a downstream process. The second opening 216 is preferably sized to allow only clusters of nanofibers having a particular size to pass through. The separator 210 may include multiple rotatable blades (not shown) designed to rotate about a vertical axis within the housing 212 to separate and open clusters of coarse nanofibers. The blades may have the same or different pitch and camber to allow for the continuous breaking or "opening" of intertwined fibers as they pass from the first opening 214 to the second opening 216. Fiberization system 150 further includes a gas flow that extends throughout the system from separator 210 to nozzle 220 (described in more detail below). The gas flow (along with a series of pumps described below) provides the motive force for moving the nanofibers through system 150. In one embodiment, the gas flow is created by an air compressor 230 configured to provide compressed air to the system, although it will be appreciated that other forms of gas may be used to transport the nanofibers through system 150. The system 150 includes one or more pumps for moving the nanofiber clusters and ultimately the individual nanoparticles throughout the system. The pumps may include any suitable pump, such as positive displacement, centrifugal, axial, etc. In one embodiment, a first pump 240 includes a first inlet fluidly connected to the air compressor 230 by a first passageway 242 and a second inlet fluidly connected to the separator 210 by a second passageway 244. Compressed air is drawn into the first pump 240, which creates a negative pressure (e.g., vacuum) to draw the nanofiber clusters from the separator 210 and into a pump (described in more detail below). The system 150 may further include second and third pumps 250, 260 fluidly connected to an outlet of the first pump 240. Similarly, the second and third pumps 250, 260 create a negative pressure to draw the nanofiber clusters through the third passageway 252.

[0045] In a particular embodiment, the pump 240 includes an eductor 300. As shown in FIG. 15, the eductor 300 includes a drive fluid inlet 302 and a nanofiber inlet 304, each of which is connected to an outlet 306 via a passageway 308. The fluid passageway 308 includes a converging inlet nozzle 310, a diffuser throat 312, and a diverging outlet diffuser 314. The high pressure, low velocity air is converted to low pressure, high velocity air, resulting in the pressure difference required for suction. Based on the Venturi effect and Bernoulli's principle, a vacuum is created using a primary fluid medium (e.g., compressed air) to draw the nanofibers into the eductor 300 and out through the outlet 306. The diameter of the eductor 300 depends on the volumetric flow rate of the compressed air, the suction requirements, the pressure loss, and the fluid pressure of the compressed air.

[0046] 13, the third passage 252 includes a branch 254 that splits the third passage 252 into two separate passages that lead to the second and third pumps 250, 260, respectively. The branch 254 preferably includes a surface or wall disposed substantially perpendicular to the third passage 252, forming a T-shaped intersection. The surface may be any surface that faces the flow of nanofibers through the passage, such as an interior wall of the passage at the branch point, or a change in direction of other interior walls, e.g., curved, vertical, etc. Alternatively, the passage may include a wall or other surface disposed within the passage or projecting into the passage within another flow path. In one embodiment, the passage may extend into a substantially T-shaped branch that includes two separate passages extending from the branch. The second eductor is configured to draw the nanofibers into the T-shaped branch at a velocity sufficient to split off at least some of the nanofibers. As the nanofiber clusters pass through the third passageway 252, they are propelled toward this surface or wall by the negative pressure applied by the second and third pumps 250, 260. The velocity of the nanofibers relative to the branch 254 causes collisions with sufficient kinetic energy to break up at least a portion of the nanofiber clusters into smaller clusters of nanofibers and / or into individual nanoparticles having at least one dimension less than 1 micron. To generate the kinetic energy necessary to break up the nanofiber clusters, air is propelled through the system 150 at a velocity of about 500 feet per minute (fpm) to about 10,000 feet per minute, preferably about 2,000 fpm to about 6,000 fpm. The system 150 includes a sufficient amount of suction pressure, preferably at least about 20 psi. This suction pressure creates an overall pressure throughout the system of at least about 100 psi.

[0047] In certain embodiments, the system 150 further includes fourth and fifth fluid passages 262, 264 connecting the outlets of the second and third pumps 250, 260 with the reactor 270. As shown in FIG. 16, the reactor 270 includes a top surface 272, a bottom surface 274, and an interior annular chamber 276 extending from the top surface 272 to the bottom surface 274. The reactor 270 further includes a central tube 275 having an open top inlet 278 and an outlet 280. The reactor 270 may further include one or more top outlets 282. The reactor 270 may be coupled to an energy source (not shown) configured to create a swirling gas vortex within the annular chamber 276. The energy source may include any suitable energy source, such as a pump, a compressor, a generator, etc. The swirling gas preferably flows from the bottom to the top of the reactor 270 around the central tube 275 , moving the nanofiber clusters and individual nanoparticles upward from the bottom surface 275 to the top surface 272 . In another embodiment, the vortex is generated without a separate energy source. In this embodiment, the clusters of nanofibers 290 and individual nanoparticles 292 enter the reactor 270 through the bottom inlets 284, 285, 286, 287. The inlets 284, 285, 286, 287 are angled upward to facilitate the movement of the nanofibers and nanoparticles around the central tube 275. In a preferred embodiment, at least one or more of the inlets 284, 285, 286, 287 are angled such that the nanofibers and nanoparticles enter the reactor 270 substantially tangentially to the central tube 275. Upon entering the annular chamber 276, the velocity vectors (speed and direction) of the nanofibers and nanoparticles create a vortex within the reactor 270, which causes the nanofibers and nanoparticles to rotate around the central tube 275 and rise to the upper portion of the chamber 276. The swirling gas preferably flows from the bottom to the top of reactor 270 around central tube 275, moving the nanofiber clusters and individual nanoparticles upward from bottom surface 275 to top surface 272. Without any obstruction, nanofibers 290 and nanoparticles 292 are blown from the bottom to the top of the reactor. The vortex within chamber 276 may further break down (e.g., open, separate, and / or individualize) the nanofiber 290 clusters as they pass through reactor 270. In some embodiments, reactor 270 may also be coupled to an energy source (not shown) configured to create a swirling gas vortex within annular chamber 276. The energy source may include any suitable energy source, such as a pump, a compressor, a generator, etc. The system 100 may further include another pump or negative pressure source (see, e.g., FIG. 17) coupled to the upper outlet 282. This negative pressure draws the fibers out of the outlet 282, resulting in fibers 290 exiting the reactor 270. Because the individual nanoparticles 292 are significantly lighter than the still clustered entangled nanofibers 290, these individual nanoparticles 292 are drawn into the upper inlet 278 of the central tube 275. Meanwhile, the larger, heavier clusters of nanofibers 290 that have not yet been broken down are drawn out of the upper outlet 284. The upper outlet 284 may be coupled to another pump (not shown), or to the first pump 240. In this manner, the clusters of nanofibers 290 are sent again through the process to be further broken down, creating a re-feed system for further breaking down the remaining nanofiber clusters. The outlet 280 of the central tube 275 is connected to a nozzle 220 (see FIG. 13). Individual nanoparticles 292 are drawn into the nozzle 220 where they are dispersed onto the surface of a substrate or into a stream of fibers (described below). The nozzle 220 may comprise any suitable nozzle known to those of skill in the art. In one embodiment, the nozzle 220 has multiple outlets with exterior dimensions tailored to the size (i.e., area) of the substrate passing under the nozzle 220. The nozzle 220 disperses the nanoparticles onto the substrate at a rate driven by the pressure of the entire system. In certain embodiments, the system 100 includes a plurality of nozzles coupled to the outlet 280 of the reactor 270. The nozzles may be arranged on the substrate in any suitable format, e.g., parallel, in series, in parallel, etc. It will be appreciated that pump 240, or pumps 250, 260, may also supply a flow of nanofiber / air mixture directly to nozzle 220 (i.e., bypassing reactor 270). In this embodiment, the pressure within the system is designed to create sufficient kinetic energy to break down or release substantially all of the nanofibers into individual nanoparticles, and reactor 270 is not required to separate the nanoparticles from larger clusters of fibers.

[0048] 17, another embodiment of a fiberization system 320 is described. As shown, the fiberization system 320 includes a separator 325 for separating large or macro-clusters of nanofibers into smaller clusters of nanofibers that pass through the system 320. A first eductor 326 is coupled to the outlet of the separator 325 and serves to draw the nanofibers from the separator 325 into the system 320. As mentioned above, an air compressor (not shown) is also coupled to the eductor 326 to provide a driving fluid. Similar to the previous embodiment, the second and third eductors 330, 340 are coupled to the outlet of the first eductor 326. The nanofibers are drawn through the first eductor 320 and propelled towards the surface of the T-junction 350 where at least a portion of the nanofibers are broken down into smaller clusters or individual nanoparticles. Each of the second and third eductors 330, 340 has an outlet connected to an additional T-junction 360, 370. As previously described, the nanofibers are propelled against the surface of the T-junction 360, 370 for further breakup. Each of the T-junctions 360, 370 is connected to two fluid passages that enter the bottom portion 380 of the reactor. The bottom portion 380 of the reactor thus has four separate inlets 382, ​​384, 386, 388 for the passage of the nanofibers. Each of these inlets is preferably angled upwards and located at opposite corners of the reactor. This allows the nanofibers to enter the vortex of the reactor and swirl up to the upper portion 390 of the reactor.

[0049] As previously described with reference to FIG. 16, the reactor includes an annular chamber with a central tube with open upper and lower ends that is connected to a nozzle. Nanofibers that have been sufficiently broken down into individual nanoparticles flow through the open upper end into the central tube and are dispersed through the nozzle. Clusters of heavier nanoparticles that have not yet been broken down exit the reactor through one of four separate outlets 392, 394, 396, 398. Eductors 410, 420 provide the driving force to draw the nanofibers out of the reactor 400, as described above. Each of the outlets 392, 394 is connected to the eductor 410 through a T-junction 412, and each of the outlets 396, 398 is connected to the eductor 420 through a T-junction 422. In this case, the nanofibers flow from two paths to one path as they pass through the junctions 412, 422. The eductors 410, 420 are connected to T-junctions 430, 440, respectively. As previously described, the nanofibers are propelled to the T-junctions 430, 440 to be further broken down into individual nanoparticles. The T-junctions 430, 440 are then connected to the bottom portion 380 of the reactor 400 (via inlets 432, 434, 442, 444), respectively. This allows the nanofibers to return to the reactor 400 for further processing. This process continues for each cluster of nanofibers until they are all broken down into nanoparticles and sent through the central tube to the nozzle. As a final step, the individualized nanofibers are air-sprayed from the nozzle onto any substrate or mixed with any fiber spin stream. In this process, the suction force is up to 20 psi and the pressure is up to 100 psi. In certain embodiments, the fiberization system 150 may include an independent control system that monitors the nanofibers to determine when they have broken down into individual nanoparticles suitable for passing through the nozzle. The control system may simply monitor the pressure throughout the system, for example, to ensure that sufficient pressure is being applied to the nanofibers to break them down into nanoparticles. Alternatively, the control system may consist of various sensors located throughout the system to detect properties such as the mass or size of the nanoparticles. The sensors may be located, for example, within the reactor 400, allowing the control system to control various parameters of the reactor 400, such as the negative pressure applied to the outlets 392, 394, 396, 398, the velocity of the vortex through the annular chamber, the pressure applied to the central tube that draws the nanoparticles into the nozzle, etc.

[0050] 18 illustrates another embodiment of a system 500 for manufacturing multiple layers of nonwoven material. As shown, the system 500 includes first and second unwinders 502, 504 and a single winder 506 for taking up first and second substrates 510, 512 passing downstream through the system 500. As with the previous embodiment, the system 500 may further include a support surface (not shown) for each of the substrates 510, 512. As described below, the first and second unwinders 502, 504 serve to advance the first and second substrates 510, 512 through a process where the substrates are brought together and taken up by the single winder 506. The system 500 includes first and second spray coaters 520, 522 positioned downstream of the first and second unwinders 502, 504, respectively, for applying a binder to the first and second substrates 510, 512. The system 500 further includes first and second fiberization systems / devices 530, 532 positioned downstream of the spray guns 520, 522, respectively. As previously described, the fiberization devices 530, 532 generate individual nanoparticles and disperse those nanoparticles on the substrates 510, 512. After the nanoparticles are dispersed within the substrates 510, 512, the two substrates are brought together at a branch point 540 and advanced downstream together. The two substrates may be bonded to each other at this point, or may simply be placed one on top of the other. The system 500 further includes a heater / drying device 550, such as an IR oven, downstream of the junction 540 of the two substrates. The heater / drying device heats and dries the two substrates to bond them together and to bond the nanoparticles to the fibers within the substrates. The substrates may be, for example, stacked on top of one another. In certain embodiments, the nanoparticles are dispersed in both substrates 510, 512. In one such embodiment, the system 500 is designed such that the nanoparticles are dispersed through a first surface of each of the substrates. The substrates can be joined such that the first surfaces face each other. Alternatively, the first surfaces may not face each other (i.e., the substrates are joined at a second, opposing surface of each substrate). In yet another embodiment, the first surface of the first substrate is joined to the second surface of the second substrate.

[0051] 19 illustrates a filter product 700 including a filter media 710 of a nonwoven material including fibers 722 and nanoparticles 720 dispersed in at least a portion of the filter media 710. As illustrated, the filter media 710 has a first upper surface 712 and a second lower surface 714. The nanoparticles are dispersed through the upper surface 712 and extend beyond the upper surface 712 into the depth of the filter media 710, as described above. The filter product 700 further includes a support layer 730, which may be any suitable support layer known in the art, such as a substantially rigid polymer that provides support to the filter media 710, or an apertured film (described above) having a plurality of apertures for gas or fluid to pass therethrough.

[0052] 20 shows another filter product 740 that includes a filter media 710 of a nonwoven material that includes fibers 722 and nanoparticles 720 dispersed throughout a portion of the filter media 710. In this embodiment, the product 740 includes a scrim layer 750 bonded to a support layer 730.

[0053] 21 illustrates a dual layer filter product 760 including first and second filter media 762, 764 bonded together. As shown, nanoparticles 720 are dispersed throughout the depth of each filter media 762, 764. In this embodiment, the nanoparticles 720 are dispersed throughout the interior surfaces 766, 768 of the filter media 762, 764. In another embodiment (not shown), the nanoparticles are dispersed throughout the exterior surfaces 770, 772 of the filter media 762, 764. In yet another embodiment, the nanoparticles 720 may be deposited on the interior surface 766 of the media 762 and the exterior surface 772 of the media 764.

[0054] In another aspect, a system for producing a nonwoven material includes a first device for generating one or more fiber streams and a second device for isolating nanoparticles in a gas medium. The second device disperses the nanoparticles in the stream and supplies the stream to the fiber stream to form the nonwoven material. The system may further include a dispersing device, such as a nozzle, coupled to the second device and configured to supply the nanoparticles substantially uniformly to the fiber stream. The fiber stream may be generated by any suitable mechanism known in the art, such as meltblown, spunbonded or spunlaced, thermally bonded, carded, airlaid, wetlaid, extrusion, co-forming, needle punched, stitched, hydroentangled, etc. In one example, the system may include a spunbond line, where molten polymer is spun and the molten filaments are stretched to form filaments. Fiber bundles of the filaments are separated, spread out, and layered over a net to form a web. The fibers are bonded in sheet form by thermal bonding and embossing. For example, the first stream 630 may be introduced before the attenuation zone or before the bonding (consolidation) process. In another embodiment, the system may include two carding machines arranged in series with each other. The first stream 630 may be introduced at any point after the first carding line and before the second carding line so that the nanoparticles are sandwiched between the two carded fibrous webs. Then, all of the fibers containing the nanoparticles are bonded in an air-through-bonding oven (the nanoparticles are thermally entangled).

[0055] Another embodiment for generating one or more fiber streams is shown in Figure 22. In this embodiment, nanoparticles are dispersed between two meltblowing dies, where the molten polymer is forced through small holes to generate molten fibers. When the nanoparticles come into contact with the fibers, which are still tacky, they mechanically entangle and thermally bond to the fibers. Thus, in some embodiments, no additional bonding process is required. 22, an apparatus 600 for forming a fibrous nonwoven structure includes a fiberization system 610 similar to one of the systems and devices described above. The fiberization system 610 includes a nozzle 620 or similar device for dispersing the individual nanoparticles into a first stream 630. The apparatus 600 further includes a system for generating one or more streams of fibers that are combined with the stream of individual nanoparticles 630. The system may include systems known in the art, such as spunbond, carding, extrusion, etc. In another embodiment, the apparatus includes first and second feeders, e.g., hoppers 640, 642, coupled to first and second extruders 650, 652. Each extruder may include, for example, an extrusion screw (not shown) driven by a conventional drive motor (not shown). As the polymer advances through the extruders 650, 652, the rotation of the extrusion screw by the drive motor gradually heats the polymer to a molten state. Heating the thermoplastic polymer to a molten state may be accomplished in multiple separate stages, with the temperature gradually being increased as it advances through separate heating zones in the extruders 650, 652 to two meltblowing dies 660, 662, respectively. The meltblowing dies 660, 662 may be yet another heating zone where the temperature of the thermoplastic resin is maintained at an elevated level for extrusion. Each meltblowing die 660, 662 is configured such that two attenuating gas streams per die converge to form a single gas stream that entrains and attenuates the molten yarn 20 as it exits a small hole or orifice 672 in the meltblowing die. The molten yarn 20 is attenuated into fibers, or, depending on the degree of attenuation, into microfibers, the small diameter of which is typically smaller than the diameter of the orifice 672. Thus, each meltblowing die 660, 662 has a corresponding single primary air stream 680, 690 of gas containing entrained attenuating polymer fibers. The primary air streams 680, 690 containing polymeric fibers are arranged to converge at the forming zone 700. Additionally, a first stream 630 of individual nanoparticles is added to the two primary air streams 680, 690 of thermoplastic polymeric fibers or microfibers at the forming zone 30. The introduction of the individual nanoparticles into the two primary air streams 680, 690 of fibers is designed to produce a distribution of secondary fibrous material 32 within the combination of the primary air streams 680, 690 of fibers. This can be achieved by merging the first stream 630 of individual nanofibers between the two primary air streams 680, 690 and causing all three gas streams to converge in a controlled manner. Examples of suitable meltblowing dies that can be utilized to produce nonwoven materials are further described in U.S. Pat. Nos. 6,972,104, 8,017,534, and 7,772,456, as well as U.S. Patent Application Publication No. 20200216979 A1, the entire disclosures of which are incorporated herein by reference for all purposes.

[0056] Embodiment 1 is a filter media comprising a substrate comprising fibers, wherein nanoparticles are disposed in the substrate, the nanoparticles having at least one dimension less than 1 micron, and at least one of the fibers or nanoparticles is electrostatically charged. Embodiment 2 is the filter media of embodiment 1, wherein the fibers are electrostatically charged.Embodiment 3 is the filter media of any one of embodiments 1 or 2, wherein the nanoparticles are electrostatically charged.In any of the embodiments disclosed herein, the substrate, the nanoparticles, or both are electrostatically charged. Embodiment 4 is the filter media of any one of embodiments 1-3, wherein the substrate comprises a triboelectric filter media. Embodiment 5 is the filter media of any one of embodiments 1-4, wherein the fibers are corona charged. Embodiment 6 is the filter media of any one of embodiments 1-5, wherein the substrate is a triboelectric filter media, and further wherein the triboelectric filter media is formed by carding and needling. Embodiment 7 is the filter media of embodiment 6, wherein the nanoparticles and fibers are needled together. Embodiment 8 is the filter media of any one of embodiments 1-7, wherein the substrate comprises a spunbond charged media.Embodiment 9 is the filter media of any one of embodiments 1-8, wherein the substrate comprises a meltblown charged media. Embodiment 10 is the filter media of any one of embodiments 1-9, wherein the substrate comprises a netting material. In any of the embodiments disclosed herein, the substrate can comprise a mesh, a woven fabric, a knitted fabric, a nonwoven fabric, or a sheet. Embodiment 11 is the filter media of any one of embodiments 1-10, wherein the fibers have a linear density of about 3 denier or greater. Embodiment 12 is the filter media of any one of embodiments 1-11, wherein the fibers have a linear density of at least about 5 denier. In any of the embodiments disclosed herein, the fibers of the substrate can include two or more different sizes of fibers. Embodiment 13 is the filter media of any one of embodiments 1-12, wherein the fibers are biocomponent fibers having a core and a sheath.Embodiment 14 is the filter media of any one of embodiments 1-13, wherein the fibers are bicomponent fibers having a core and a sheath, and further wherein the core is eccentric from the sheath. Embodiment 15 is the filter media of any one of embodiments 1-14, wherein at least a portion of the nanoparticles are disposed in the substrate from the first surface to the second surface opposite the first surface.Embodiment 16 is the filter media of any one of embodiments 1-15, wherein the nanoparticles form a gradient in the substrate such that the density of individual nanoparticles decreases from the first surface to the second surface opposite the first surface.Embodiment 17 is the filter media of any one of embodiments 1-15, wherein the nanoparticles are substantially uniformly dispersed throughout the fibrous substrate. Embodiment 18 is a filter media of any one of embodiments 1-17, wherein the nanoparticles are isolated within the fluid and dispersed throughout the first surface of the substrate. Embodiment 19 is the filter media of any one of embodiments 1-18, wherein the nanoparticles are selected from the group consisting of carbon fibers, glass fibers, polypropylene fibers, nylon fibers, polylactic acid fibers, and combinations thereof. Embodiment 20 is the filter media of any one of embodiments 1-19, further comprising a binder in the fibrous material that binds the nanoparticles to the fibers.Embodiment 21 is the filter media of any one of embodiments 1-19, further comprising a binder, the binder comprising a material selected from the group consisting of starch, dextrin, guar gum, PVOH, and synthetic resins.Embodiment 22 is the filter media of any one of embodiments 1-19, wherein the fibers comprise a binder composition that binds the nanoparticles to the fibers. Embodiment 23 is an air filtration product comprising the filter media of any one of embodiments 1-22. Embodiment 24 is a filter media comprising a substrate comprising fibers and nanoparticles, where the substrate mechanically filters contaminants and the substrate electrostatically filters contaminants. Embodiment 25 is the filter medium of embodiment 24, wherein the nanoparticles mechanically filter contaminants.Embodiment 26 is the filter medium of any one of embodiments 24 or 25, wherein the fibers are electrostatically charged. Embodiment 27 is the filter media of any one of embodiments 24-26, wherein the substrate comprises a triboelectric filter media. Embodiment 28 is the filter media of any one of embodiments 24-27, wherein the substrate is a triboelectric filter media, and further wherein the triboelectric filter media is formed by carding and needling. Embodiment 29 is the filter media of any one of embodiments 24-28, wherein the anoparticles and fibers are needled together. Embodiment 30 is the filter media of any one of embodiments 24-29, wherein the substrate comprises a spunbond charged media.Embodiment 31 is the filter media of any one of embodiments 24-30, wherein the substrate comprises a meltblown charged media. Embodiment 32 is the filter media of any one of embodiments 24-31, wherein the substrate comprises a netting material. In any of the embodiments described herein, the substrate can be a mesh, a woven fabric, a knit fabric, a nonwoven fabric, or a sheet. Embodiment 33 is an air filter comprising the filter medium of any one of embodiments 24-32. Embodiment 34 is a method of making a filter media, the method including providing a substrate including fibers, electrostatically charging the fibers, and dispersing nanoparticles in the substrate. Embodiment 35 is the method of embodiment 34, further comprising corona charging the fibers. Embodiment 36 is the method of embodiment 34, further comprising triboelectrically charging the fibers. Embodiment 37 is the method of embodiment 34, further comprising electrospinning the fibers. Embodiment 38 is the method of embodiment 34, further comprising needling the fibers and nanoparticles together. Embodiment 39 is the method of embodiment 34, further comprising carding the fibers. Embodiment 40 is the method of any one of embodiments 34-39, further comprising spunbonding the fibers. Embodiment 41 is the method of any one of embodiments 34-40, further comprising meltblowing the fibers. Embodiment 42 is the method of any one of embodiments 34 to 41, further comprising dispersing the nanoparticles on the first surface of the substrate such that the nanoparticles penetrate at least the first surface of the substrate. Embodiment 43 is the method of any one of embodiments 34 to 42, further comprising isolating individual nanoparticles within the fluid, the individual nanoparticles having at least one dimension less than 1 micron.

[0057] Example 1 A bicomponent microfiber substrate having an inner polyester circular section and an outer HDPE concentric circular section was provided in roll form. In a roll-to-roll process, the substrate was sprayed with an adhesive and biosoluble glass fiber nanofibers or nanoparticles were deposited on it. The nonwoven product was then heated in an oven and the cooled nonwoven product was collected on another roll. The nanoparticles are deposited according to the process described in Figures 12-16 below. Biosoluble glass nanofibers are used in the experiments. The nanofibers have a diameter of about 700 nm and a length of about 500 microns. A carded air-through bonded nonwoven fabric made of bicomponent fibers is used as the substrate in the following examples. Flat sheet filter media samples were tested at a filtration rate of 110 fpm. The sample size was 12" x 12". NaCl salt particles ranging from 0.3 to 10 microns were used as the contaminant.

[0058] Example 2 A carded nonwoven fabric made of 3 denier PET / PE bicomponent fibers is used as the substrate. A composition containing water, 2-hexoxyethanol, isopropanolamine, sodium dodecylbenzenesulfonate, lauramine oxide, and ammonium hydroxide is used as the binder. Different nanofiber add-on amounts are controlled by adjusting the line speed. [Table 1] This example shows that by controlling the amount of nanoparticle add-on, the MERV rating can be increased from MERV 7 to MERV 13.

[0059] Example 3 A high loft air-through carded nonwoven with 5 denier bicomponent fibers is used as the substrate. A typical starch binder is diluted and sprayed prior to nanofiber dispersion. The solvent evaporates under an IR heater and the starch binds the nanofibers well as drying occurs. [Table 2]

[0060] Example 4 Spunbond or meltblown media were used as the substrate, and nanoparticles were incorporated into the substrate after IPA release as described herein. Spunbond fibers were made by spinning and drawing molten polymer to form filaments. The substrate had an average basis weight of about 90 gsm and an average thickness of about 0.57 mm. A base sample was used that did not incorporate nanoparticles. Four separate samples were prepared with nanoparticles incorporated into the substrate as described herein. In sample 2, nanoparticles were incorporated into the meltblown fibers after IPA release. In samples 1, 3, and 4, nanoparticles were incorporated into the spunbond fibers after IPA release. The results of this test are summarized in Table 3 below. [Table 3] As shown, the efficiency of the filter media samples incorporating nanoparticles increased over the base sample for all three particle groups, with a significant increase for the E2 and E3 particle groups. The overall MERV rating of the samples increased from MERV 7 (base sample) to MERV 12-MERV 16 (with nanoparticles). The base sample without nanoparticles exhibited a pressure drop of 0.07 inches of water. Samples 1-4 had slightly increased pressure drops ranging from 0.17-0.41 inches of water. Sample 2, in which nanoparticles were incorporated into the meltblown fibers, had a MERV rating of 14 and a pressure drop of 0.24 inches of water.

[0061] Example 5 5 denier air-through carded fiber was used as the substate. A base sample was used that did not incorporate nanoparticles. Two separate samples were prepared with nanoparticles incorporated into the substrate as described herein. The results of this testing are summarized in Table 4 below. [Table 4] As shown, the efficiency of the filter media samples incorporating nanoparticles increased substantially over the base sample for all three particle groups. The overall MERV rating of the samples increased from MERV 6 (base sample) to MERV 13 (with nanoparticles). The base sample without nanoparticles exhibited a pressure drop of 0.03 inches of water. Sample 1 had a slightly increased pressure drop ranging from 0.31 to 0.33 inches of water.

[0062] Example 6 Meltblown fibers were used as the substrate. The substrate had an average basis weight of 24 gsm and an average thickness of about 0.4 mm. Base samples were used that did not incorporate nanoparticles or adhesives such as PVOH. Sample 1 included meltblown fibers with the belt side up. PVOH was sprayed onto the fibers, but no nanoparticles were incorporated therein. Sample 2 included meltblown fibers with the nap side up. PVOH was sprayed onto the fibers, but no nanoparticles were incorporated therein. Sample 3 included meltblown fibers with PVOH sprayed onto them and nanoparticles incorporated into the fibers as described herein. The results of this testing are summarized in Table 5 below. [Table 5] As shown, the efficiency of Sample 3 incorporating nanoparticles increased over the other three base samples in all three particle groups, especially the E1 particle group. The overall MERV rating of Sample 3 increased from MERV 13 or 14 (base samples) to MERV 15 (with nanoparticles). The addition of PVOH to Samples 2 and 3 did not substantially increase the pressure drop (i.e., 0.35 for the base sample, 0.38 and 0.41 for Samples 1 and 2). The pressure drop for Sample 3 increased from about 0.40 inches of water column to about 1 inch of water column. In Sample 3, nanoparticles were incorporated into the meltblown fibers, resulting in a MERV rating of 15 and a pressure drop of 1.02 inches of water column.

[0063] Example 7 Five denier air-through carded fibers were used as the substate. A base sample was used that did not incorporate nanoparticles. Seven additional samples were prepared that included five denier carded fibers with nanoparticles incorporated into the substrate as described herein. The results of this testing are summarized in Table 6 below. [Table 6] As shown, the efficiency of the seven samples incorporating nanoparticles increased over the base sample for all three particle sizes, especially for the E2 and E3 particle sizes. The overall MERV rating increased from MERV 6 (base sample) to MERV 7-MERV 13 (with nanoparticles). Pressure drop only increased from 0.03 inches of water column to a maximum of 0.32 inH2O.

[0064] Example 8 High loft spunbond fibers were used as the substate in a continuous fiber line. The test included two different versions: 205-6 and 205-2, in which the continuous fiber line configuration was modified to produce two substrates of different weight and thickness. For each version (205-6 and 205-2), a base sample was used that did not incorporate nanoparticles. An additional six samples were prepared that included 205-6 and 205-2 fibers with nanoparticles incorporated into the substrate as described herein. The results of this test are summarized in Table 7 below. [Table 7] As shown, the efficiency of the six samples incorporating nanoparticles showed substantially increased efficiency over the base sample for all three particle groups. The overall MERV rating increased from MERV 6 (base sample) to MERV 11-MERV 14 (with nanoparticles). Pressure drop only increased from 0.04 inches of water column to a maximum of 0.87 inches of water column. Pressure drop for the 205-2 sample only increased to a maximum of 0.48 inH2O.

[0065] Example 9 Spunbond and meltblown fibers were used as substrates. The average basis weight of the substrate was about 70 gsm for the spunbond fibers and about 24 gsm for the meltblown fibers, and the average thickness of the substrate was about 0.75 mm. A base sample was used that did not incorporate nanoparticles. Five additional samples were prepared that included spunbond + meltblown fibers with nanoparticles in the fibers as described herein. In Samples 1-3, nanoparticles were sprayed onto the meltblown fibers. In Samples 4 and 5, nanoparticles were sprayed onto the spunbond fibers. Also, in Samples 1 and 2, the adhesive PVOH was not sprayed onto the substrate. PVOH was sprayed onto Samples 3-5. The results of this testing are summarized in Table 8 below. [Table 8] As shown, the efficiency of the five samples incorporating nanoparticles showed substantially increased efficiency over the base sample for all three particle groups. The overall MERV rating increased from MERV 5 (base sample) to MERV 16 (with nanoparticles). The pressure drop only increased from 0.07 inches of water column to a maximum of 0.56 inches of water column. For samples 3-5 (PVOH sprayed onto the substrate), the pressure drop only increased to a maximum of 0.4 inches of water column.

[0066] Example 10 Five denier air-through carded glass fiber was used as the substate. A base sample was used that did not incorporate nanoparticles. Three additional samples were prepared that contained five denier carded glass fiber that incorporated nanoparticles. The results of this testing are summarized in Table 9 below. [Table 9] As shown, the efficiency of the three samples incorporating nanoparticles showed substantially increased efficiency over the base sample for all three particle groups. The overall MERV rating increased from MERV 6 (base sample) to MERV 12-MERV 13 (with nanoparticles). The pressure drop only increased from 0.03 inches of water column to a maximum of 0.27 inches of water column.

[0067] Example 11 A fiber blend of 5 denier and 7 denier air-through carded glass fibers was used as the substate. The media was air-through bonded. A base sample was used that did not incorporate nanoparticles. Nineteen additional samples were prepared that included fiber blends of 5 denier and 7 denier carded glass fibers with nanoparticles incorporated therein. The results of this testing are summarized in Table 10 below. [Table 10] As shown, the efficiency of all 19 samples incorporating nanoparticles showed substantially increased efficiency over the base sample for all three particle groups. Overall MERV ratings increased from MERV 6 (base sample) to MERV 10-13 (with nanoparticles) (the majority of samples were rated MERV 13). Pressure drop only increased from 0.03 inches of water column to a maximum of 0.31 inches of water column.

[0068] Although the devices, systems, and methods have been described in detail herein according to certain preferred embodiments thereof, numerous modifications and changes may be implemented by those skilled in the art. Accordingly, the above description should not be construed as limited thereby, but should be construed to include the obvious variations described above, and should be limited only by the spirit and scope of the following claims.

Claims

1. A substrate containing fibers, Nanoparticles disposed in the substrate, wherein at least one dimension is less than 1 micron, A filter medium comprising the fibers or nanoparticles, wherein at least one of the fibers or nanoparticles is electrostatically charged.

2. A filter medium comprising a substrate containing fibers and nanoparticles, The aforementioned substrate mechanically filters out contaminants, The substrate electrostatically filters out contaminants. Filter medium.

3. The filter medium according to claim 1 or 2, wherein the fibers are electrostatically charged.

4. The filter medium according to claim 1 or 2, wherein the nanoparticles are electrostatically charged.

5. The filter medium according to claim 1 or 2, wherein the substrate includes a triboelectric filter medium.

6. The filter medium according to claim 1 or 2, wherein the fibers are corona charged.

7. The filter medium according to claim 1 or 2, wherein the nanoparticles and the fibers are needle-processed together.

8. The filter medium according to claim 1 or 2, wherein the substrate includes a spunbond-charged medium.

9. The filter medium according to claim 1 or 2, wherein the substrate includes a meltblown charged medium.

10. The filter medium according to claim 1 or 2, wherein the base material includes a net material.

11. The filter medium according to claim 1 or 2, wherein the fibers have a linear density of about 3 denier or more.

12. The filter medium according to claim 1 or 2, wherein the fibers have a linear density of at least about 5 denier.

13. The filter medium according to claim 1 or 2, wherein at least a portion of the nanoparticles are arranged in the substrate from a first surface to a second surface opposite the first surface.

14. The filter medium according to claim 13, wherein the nanoparticles are substantially uniformly dispersed throughout the fibrous substrate.

15. The filter medium according to claim 1 or 2, wherein the nanoparticles are isolated in a fluid and dispersed through a first surface of the substrate.

16. The filter medium according to claim 1 or 2, wherein the nanoparticles are selected from the group consisting of carbon fibers, glass fibers, polypropylene fibers, nylon fibers, polylactic acid fibers, and combinations thereof.

17. The filter medium according to claim 1 or 2, further comprising a binder in a fibrous material that binds the nanoparticles to the fibers, wherein the binder comprises a material selected from the group consisting of starch, dextrin, guar gum, PVOH, and synthetic resin.

18. The filter medium according to claim 1 or 2, wherein the fibers include a binder composition that binds the nanoparticles to the fibers.

19. An air filter product comprising the filter medium described in claim 1 or 2.

20. The filter medium according to claim 2, wherein the nanoparticles mechanically filter out contaminants.

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