Dual layer gas filters and systems and methods for making them - Patents.com

Abstract

Filter media and filters are provided that include at least two layers and a plurality of nanoparticles distributed in depth within at least one of the layers. The gas filter includes a first fibrous layer, a second fibrous layer bonded to the first layer, and a plurality of nanoparticles incorporated into the first layer. The nanoparticles increase the total surface area within the filter, thereby improving its filtration efficiency and allowing for the capture of submicron contaminants without significantly compromising other factors such as the pressure drop (i.e., air flow rate) of the filter. Furthermore, the filters disclosed herein can withstand rigorous pretreatment and achieve the same level of filtration performance over the life of the filter. Systems, devices, and methods for manufacturing such filters are also provided.

Description

[Technical field]

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

[0002] The present specification relates generally to gas filters having at least two layers, with nanoparticles incorporated into at least one of the layers, and systems and methods for making such gas filters. [Background technology]

[0003] Fibrous materials are particularly useful for trapping contaminants within filtration devices due to their fine fiber size. The fibers of the filter media are measured in micrometers and can be spunbonded, meltblown, electrospun, or formed by other techniques. The fine fibers trap contaminants in the filter media as fluid flows through the filter media. The two main types of filtration devices incorporating fibrous materials are surface filters and depth filters. Surface filters, such as membranes or films, act as a barrier to contaminants, capturing them before they enter the media structure. These surface filters typically have submicron pore sizes and narrow pore size distributions. Surface filters tend to have relatively high particle capture efficiencies. However, they also have relatively high pressure drop and low dust loading capacities. The high pressure drop reduces the air flow rate through the filter. The low dust loading capacity significantly shortens the filter's lifespan. Thus, surface filters have only limited use in the air filtration industry.

[0004] Depth filters are commonly employed in air filtration devices that have medium to high efficiency, low pressure drop, and relatively high dust loading capacity. Traditional residential and commercial air filters, such as HEPA filters, are typically rated by their ability to filter particles between about 0.3 and 10 microns in size. This rating, called the Minimum Efficiency Reporting Value or MERV, was developed by the American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE). MERV ratings range from 1 to 16, with higher numbers indicating greater efficiency in capturing a particular type of particle. Contaminants come in a wide range of sizes. However, contaminants smaller than 1 micron are the most harmful particles to humans and are relatively difficult to filter. For example, traditional mechanical air filters typically report a MERV rating of about 8 to 10 for their fibrous filter media. Therefore, these filter media typically do not capture sub-micron particles such as viruses and other harmful pathogens.

[0005] 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 fibrous materials using triboelectric charging, corona discharge, hydrocharging, electrostatic fiber spinning, or other known methods. Electrostatic filters are most effective at capturing submicron particles, reasonably effective at capturing particles between 1-3 microns in size, and minimally effective at capturing larger particles between 3-10 microns. Electrostatic fibers are commonly used in many filtration applications, such as face masks and high-efficiency filters to filter submicron contaminants such as viruses. One drawback of electrostatic filters is that the electrostatic charge decays over time and with use of the filter. Thus, the efficiency of the filter decreases relatively quickly, resulting in a shortened lifespan. For example, an electrostatic filter with an initial MERV rating of 13 may lose at least 2-3 points of 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.

[0006] Another method for capturing sub-micron contaminants is to use nanoparticles in combination with fibers. A filtration system can employ a filter medium that includes relatively large fibers with diameters measured in micrometers and relatively small nanoparticles. The nanoparticles increase the surface area within the filter medium for capturing particles by reducing the overall fiber size within the filter medium. The nanoparticles also tend to collapse together and increase the packing density within the filter medium. It has been shown that even a small amount of nanometer-sized fibers formed into a layer on a microfiber material can improve the filtration properties of the material. The most common method of incorporating nanoparticles into filter media is to apply a thin layer of continuous nanofibers by electrospinning to a nonwoven substrate. The nanoparticles usually extend parallel or perpendicular 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 media in which a continuous nanofiber layer is deposited on the substrate surface. Also, U.S. Patent No. 10,799,820 discloses an air filtration medium that includes a continuous nanofiber layer on the surface of the filter media.

[0007] Existing filter media incorporating nanoparticles have improved the relative efficiency of these filters, but the commercial viability of these filters is limited in certain applications because the nanoparticles are typically dispersed on the surface of the nonwoven material, and this relatively thin layer of nanoparticles on the filter surface provides only limited filtration of particles and has a relatively low dust retention capacity. Many attempts have been made to incorporate nanomaterials into filter media to increase the overall filtration efficiency, but these attempts have been limited to the so-called "wet-laid" method. 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. Patent No. 10,252,201 discloses a filter media consisting of a mixture of short-cut nanofibers and short-cut coarse fibers formed by a wet-laid method. Similarly, U.S. Patent Application No. 2021 / 0023813 discloses a method for producing a composite structure consisting of a continuous fiber nonwoven substrate and discontinuous fibers such as carbon nanofibers. The method involves stretching a continuous fiber nonwoven substrate through a slurry of discontinuous fibers in which nanomaterials are embedded in the nonwoven substrate.

[0008] While these constructions have demonstrated improved efficiency, other issues arise, such as a decrease in lifespan and / or efficiency as the filter media is subjected to normal use conditions. Additionally, these wet-laid methods have not been successful in incorporating the nanoparticles uniformly throughout the nonwoven material, resulting in agglomeration of the nanoparticles within the material, thereby further reducing its efficiency and overall dust holding capacity. Therefore, what is needed is a gas filter, as well as a system and method for manufacturing such a filter. It is particularly desirable to incorporate nanoparticles into at least a portion of a gas filter, thereby improving the performance characteristics of the filter. Summary of the Invention

[0009] 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. It is not intended to identify key or critical elements of the claimed subject matter, nor to delineate the scope of the claimed subject matter. Its sole purpose is to present some concepts of the claimed subject matter in a simplified form as a prelude to the more detailed description that is presented later. Filtration media and filters, such as air filters, face masks, gas turbine and compressor intake filters, panel filters, and the like, are provided that include at least two layers and include a plurality of nanoparticles dispersed in a depth direction within at least one of the layers. Systems, devices, and methods for manufacturing such filters are also provided.

[0010] In one embodiment, a gas filter includes a first fibrous layer, a second fibrous layer bonded to the first layer, and a plurality of nanoparticles incorporated into the first layer. The nanoparticles increase the total surface area within the filter, thereby improving its filtration efficiency, allowing for the capture of submicron contaminants without significantly compromising other factors such as the pressure drop (i.e., air flow rate) of the filter. Furthermore, the filters disclosed herein can withstand rigorous pretreatment and achieve the same level of filtration performance over the life of the filter. The first layer of the gas filter defines a first surface and a second surface opposite the first surface. The nanoparticles are disposed on the first surface and in the internal structure of the first layer between the first surface and the second surface. In certain embodiments, the nanoparticles are distributed "depth-wise" within the first layer. As used herein, the term "depth-wise" means that the nanoparticles are distributed beyond the first surface of the layer such that at least a portion of the nanoparticles are disposed between the first surface and the opposite second surface of the internal structure of the layer or filter media. In certain embodiments, the nanoparticles are distributed substantially throughout the medium from the first surface to the opposite second surface. In other embodiments, the nanoparticles are distributed in a portion of the medium from the first surface to a position between the first leaf surface and the second surface. In other embodiments, the nanoparticles are disposed in a density gradient from the first surface to the opposite second surface of the substrate. The density of the nanoparticles may be higher at either the first surface or the second surface.

[0011] The second layer of the gas filter may be adhered to the first or second surface of the first layer. In certain embodiments, a plurality of nanoparticles are also incorporated into the second layer. The nanoparticles may be dispersed throughout the internal structure of the second layer. The nanoparticles may be arranged in a density gradient from one surface of the second layer to the other surface. In this embodiment, the nanoparticles are denser at the dispersion surface (i.e., the surface where the nanoparticles are dispersed) than at the opposite surface of the second layer. The first and second layers may be bonded together with their dispersion surfaces facing each other (i.e., the side with the greater density of nanoparticles is on the inside of the gas filter). Alternatively, the first and second layers may be bonded together with their dispersion surfaces facing away from each other, with the side with the greater density of nanoparticles on the outside of the gas filter. In yet another embodiment, the dispersion surfaces alternate, such that one of the layers contains a greater density of nanoparticles on the inside and the other layer contains a greater density of nanoparticles on the outside of the gas filter. In another embodiment, the first layer of the gas filter may have a linear density greater than about 3 denier. Air filter fibers generally 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. Applicant has surprisingly discovered that by using nanoparticles dispersed in the filter media, the fibers may have a greater linear density, for example, greater than 3 denier. This is because the nanoparticles provide significant filtering capacity. In some cases, the fibers may have a linear density greater than 3 denier, greater than 5 denier, greater than 6 denier, or even 7-10 denier.

[0012] Applicant has also discovered that in some applications, fibers having a greater linear density than those used in conventional filters (e.g., greater than about 3 denier) provide more open space or pores within the filter media, which allows for a greater density of nanoparticles to be dispersed therein. Although this may be contrary to common knowledge to those skilled in the art, Applicant has discovered that fibers having a greater linear density incorporating nanoparticles actually improve the overall efficiency of the filter. In certain embodiments, the filter medium may include at least two different fiber thicknesses or linear densities to provide at least two different filter layers within the same filter medium. For example, in some cases, a portion of the filter medium includes fibers having a linear density greater than 3 denier, such as 5 denier or more or 6 denier or more. A second layer of the filter medium includes fibers having a linear density of 3 denier or less. This dual-layer filter medium forms a first filter layer that primarily filters contaminants with nanoparticles having a high density in the thicker fibers, and a second filter layer that primarily filters contaminants with fibers having a lower linear density, although both portions may include nanoparticles dispersed throughout the fibers. In certain embodiments, the filter may include three or more separate portions or layers with different denier fiber ranges within each portion.

[0013] The first and second layers may comprise any substrate, such as a sheet, layer, film, apertured film, mesh, netting, or other medium. In certain embodiments, the substrate comprises a fibrous material, which has a structure of individual fibers or threads laminated together. Examples of suitable fibrous materials include, but are not limited to, meltblown, spunbonded, bonded carded, airlaid, co-molded, or hydro-entangled fibers, layers, or webs. In other embodiments, woven fabrics or woven fabrics are contemplated as substrates. In some embodiments, the filter includes one or more support layers attached to the filter media. The support layer and / or the filter media may include nanoparticles dispersed depthwise within the layer. In some embodiments, a polymer layer, membrane or film is provided that includes one or more openings for gas or liquid flow, with the nanoparticles disposed depthwise within the polymer layer.

[0014] In another aspect, a system for manufacturing a dual layer filter includes a feeder for advancing a first fibrous layer from an upstream end to a downstream end and a dispersing device between the upstream and downstream ends for dispersing nanoparticles onto a first surface of the first layer such that the nanoparticles penetrate at least the first surface of the first layer, The system further includes a device for adhering the first layer to a second fibrous layer. In certain embodiments, the system includes a second feeder for advancing a second fibrous layer. The first feeder and the second feeder may include a winder that feeds the layers through the system to a junction point where the two layers are then bonded together. The layers may be bonded together in any suitable manner known in the art, such as by lamination. In certain embodiments, the feeder may further include a support surface extending between the two winders to support the fibrous layer as it moves downstream through the system. In other embodiments, the substrate is unwound directly from the unwinder to the winder without a separate support surface. In certain embodiments, the system includes a second dispersing device dispersing the nanoparticles into the first surface of the second layer such that the nanoparticles penetrate at least the first surface of the second layer. The first and second dispersing devices can be configured such that the first surface of the first layer is adhered to the first surface of the second layer. In other embodiments, the first and second dispersing devices are configured such that the second surface of the first layer opposite the first surface of the first layer is adhered to the second surface of the second layer opposite the first surface of the second layer. Alternatively, the first and second dispersing devices are configured such that the first surface of the first layer is adhered to the second surface of the second layer opposite the first surface of the second layer.

[0015] The system may further include a fiberizer for separating and / or singulating the nanoparticles in a fluid or gas medium. The term "fiberization" as used herein means converting (e.g., opening, separating, singulating, and / or separating) clusters, clumps, or other groups of nanoparticles into individual nanoparticles with at least one dimension less than 1 micron. In one embodiment, the nanoparticles are separated or singulated in a suitable gas medium, such as helium, nitrogen, oxygen, carbon dioxide, and dispersed by a gas flow, aerosol, vaporizer, nebulizer, or other suitable delivery mechanism. By separating and / or singulating the individual nanoparticles in a gas medium and then dispersing them in a substrate or gas flow, the nanoparticles can be more uniformly distributed throughout the layer of the gas filter. The second apparatus may further include a negative pressure source or vacuum disposed under the substrate opposite the first nozzle and / or the second nozzle to enhance penetration depth and uniformity of the nanoparticles. The negative pressure source may be any suitable suction device that draws the nanoparticles through the substrate, such as a suction pump. The system may further include a coating device for dispersing a binder on the fibers of the first layer and / or the second layer. The binder may include a variety of conventional materials, including natural materials such as starch, dextrin, guar gum, or synthetic resins such as EVA, PVA, PVOH, SBR, polyglycolide, etc. In some embodiments, the substrate includes 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 includes biocomponent fibers, one of the components including an outer sheath at least partially surrounding an inner core. The second apparatus may further include a dryer, such as an IR oven, located near the downstream end of the feeding apparatus to heat the nanoparticles and fibers to bond the nanoparticles and fibers within the substrate.

[0016] In another aspect, a method for making a dual layer filter includes providing a first layer and a second layer, each comprising fibers, dispersing nanoparticles on a first surface of the first layer such that the nanoparticles permeate at least the first surface of the first layer, and adhering the first layer to the second layer to form a filter medium. In certain embodiments, the method further comprises dispersing the nanoparticles in the first surface of the second layer such that the nanoparticles penetrate at least the first surface of the second layer. The first surface of the first layer can be adhered to the first or second surface of the second layer. Alternatively, the second surface of the first layer can be adhered to the first or second surface of the second layer. The nanoparticles can be separated or singulated within a fluid or gas medium and then dispersed substantially throughout the first and / or second layers of the gas layer, hi some embodiments, the nanoparticles can form a gradient within the first and / or second layers such that the density of the nanoparticles decreases from one surface to the other.

[0017] A binder can be applied to the fibers in the first layer and / or the second layer to hold the nanoparticles within the layer. Binders can include a variety of conventional materials, including natural 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, a 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. The description herein of desirable objects met by various embodiments of the present specification is not meant to imply or suggest that any or all of these objects are present as essential features, either individually or collectively, in the most general embodiment of the present specification or in any of its more specific embodiments. [Brief description of the drawings]

[0018] [Figure 1] FIG. 1 is a side view of a fibrous material having nanoparticles dispersed throughout a portion of the material. [Diagram 2] FIG. 2 is a side view of a fibrous material having nanoparticles dispersed throughout the material. [Diagram 3] FIG. 3 is a side view of a fibrous material having nanoparticles dispersed in a gradient throughout the material. [Figure 4] FIG. 4 shows a dual layer filter medium. [Figure 5A-5C] 5A-5C show biocomponent fibers incorporated into a fibrous material. [Figure 6] FIG. 6 shows a pleated fibrous filter medium. [Figure 7] FIG. 7 shows a typical air filter. [Figure 8] FIG. 8 shows a gas filter having first and second support membranes and a filter medium. [Figure 9A-9B] 9A and 9B show an apertured film for use as a support membrane. [Figure 10A-10E] 10A-10E show various embodiments of apertured films having nanoparticles incorporated into the film. [Figure 11] FIG. 11 shows a gas filter. [Figure 12] FIG. 12 illustrates a schematic of a system for producing a fibrous material within a substrate. [Figure 13] FIG. 13 shows a schematic of a system for converting nanofiber clusters into individual nanoparticles. [Figures 14A-14C] 14A-14C are photographs of a macrocluster of nanofibers, a smaller cluster of nanofibers, and individually isolated nanoparticles, respectively. [Figure 15] FIG. 15 shows the exhaust arrangement of the system of FIG. [Figure 16] FIG. 16 shows the reactor of the system of FIG. [Figure 17] FIG. 17 shows another embodiment of a system for converting clusters of nanofibers into individual nanoparticles. [Figure 18] FIG. 18 shows a system for producing a dual layer fibrous material. [Figure 19] FIG. 19 shows a fibrous material with nanoparticles dispersed through the depth of the material. [Figure 20] FIG. 20 shows a fibrous material having nanoparticles dispersed through the depth of the material and a scrim layer overlying the nanoparticles. [Figure 21] FIG. 21 shows a bi-layered fibrous material with nanoparticles dispersed on the inner surface of the two layers. [Figure 22] FIG. 22 illustrates another embodiment of a system for producing a fibrous material in a fluid stream. [Figure 23A] FIG. 23A is a photograph of a fibrous material without the use of a binder. [Figure 23B] FIG. 23B is a photograph of a fibrous material with a binder. [Figure 24A] FIG. 24A is a photograph of a fibrous material with nanoparticles dispersed as clumps or clusters throughout the material. [Figure 24B] FIG. 24B is a photograph of a fibrous material with nanoparticles substantially uniformly dispersed throughout the material. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0019] This specification and the accompanying drawings show exemplary embodiments and should not be considered limiting, with the claims defining the scope of this specification, including equivalents. Various mechanical, compositional, structural, and operational changes can be made without departing from the scope of this specification and claims, including equivalents. In some cases, well-known structures and techniques have not been shown or described in detail to avoid obscuring the description. Like numbers in two or more figures represent the same or similar elements. Furthermore, elements and their associated aspects described in detail with reference to one embodiment may, where possible, be included in other embodiments where they 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, it can still be said that the element is included in the second embodiment. Furthermore, the depictions in this specification are for illustrative purposes and do not necessarily reflect the actual shape, size, or dimensions of the system or illustrated parts.

[0020] It should be noted that, as used in this specification and the appended claims, the singular forms "a," "an," and "the," as well as the use of the singular form of any word, include plural referents unless expressly and unambiguously limited to one referent. As used herein, the term "include" 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 listed items. Unless otherwise indicated, all quantitative values ​​are approximations, 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.

[0021] Filtration media and filters, such as air filters, face masks, gas turbine and compressor intake filters, panel filters, etc., are provided that include at least two layers and a plurality of nanoparticles dispersed depthwise within at least one of the layers. Systems, apparatus and methods for manufacturing such filters are also provided. As used herein, the term "nanoparticle" refers to any particle having at least one axis or dimension less than 1 micron. For example, a fiber having a diameter or width less than 1 micron and a length greater than 1 micron is a nanoparticle as used herein. In certain embodiments, each individual nanoparticle can be a small particle ranging in size between about 1 and about 1000 nanometers, preferably in the range of about 1 to about 650 nanometers. At least half of the particles in the number size distribution can be estimated to be 100 nanometers or less. The majority of nanoparticles are usually 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 becomes large and the surface atoms of the material dominate the material performance. Because of their very small size, nanoparticles have a very large surface area to volume ratio when 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 their electrons and create quantum effects. In some embodiments, the nanoparticles comprise nanofibers that have at least one dimension (i.e., diameter, width, height, etc., depending on the cross-sectional shape of the fiber) that is less than 1 micron. 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.

[0022] In certain embodiments, the filter media is a nonwoven substrate that includes a structure of individual fibers or threads that are overlapped, connected, or bonded to each other. Nonwovens can include sheet or web structures that are bonded together by mechanically, thermally, or chemically entangling fibers or filaments (and by perforating films). They can be substantially flat, porous sheets made from separate fibers or directly from molten plastic or plastic films. Examples of suitable nonwoven materials include, but are not limited to, meltblown, spunbonded or spunlaced, heat-bonded, bonded carded, airlaid, wetlaid, co-molded, needle punched, stitched, hydraulically entangled fibers, layers, or webs, and the like. 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 knit, warp knit, knit mesh panels, compressed knit mesh, and the like. Woven materials suitable for filter applications include woven filter media such as monofilament woven fabrics, multifilament woven fabrics, nylon mesh, polyester mesh, polypropylene mesh, and the like. Woven fabrics can be used, for example, in mesh filter press cloths, woven filter pads and other die-cut pieces, centrifuge 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 fibrous textile material may include structures that include intertwined or entangled short-cut fibers and / or filaments. As used herein, short-cut fibers refer to fibers of finite length. As used herein, filaments refer to fibers having a substantially continuous length. In some embodiments, the substrate may include short-cut coarse fibers, 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.

[0023] In certain embodiments, the nanoparticles are "depth-wise" dispersed within the substrate. As used herein, the term "depth-wise" means that the nanoparticles are dispersed beyond a first surface of the substrate such that at least a portion of the nanoparticles are disposed within the internal structure of the substrate or medium between the first surface and an opposing second surface. In certain embodiments, the nanoparticles are dispersed substantially throughout the medium from the first surface to the opposing second surface. In other embodiments, the nanoparticles are dispersed in a 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., air and other gases) to pass through the filter, thereby reducing the total pressure drop of the filter. In other embodiments, the nanoparticles are arranged to produce a density gradient through the thickness of the substrate, with higher density nanoparticles located near one surface than the opposite surface, or with higher density nanoparticles located at the surface compared to the central portion of the substrate. The density gradient exhibited may be substantially linear, may decrease in a series of discrete steps, or may be random in gradient (i.e., a general decrease in density that is neither linear nor step-wise). This density gradient provides a number of advantageous features for certain applications, such as filters (as described below).

[0024] The nanoparticles may comprise any suitable material, such as glass, biosoluble glass, ceramic materials, acrylic, carbon, metals, such as alumina, polymers (e.g., nylon, polyethylene terephalate, etc.), polyvinyl chloride (PVC), polyolefins, polyacetals, polyesters, cellulous ethers, polyalkylene sulfides, poly(arylene oxides), polysulfones, modified polysulfone polymers and polyvinyl alcohols, polyamides, polystyrenes, polyacrylonitriles, polyvinylidene chloride, polymethyl methacrylate, polyvinylidene fluoride, and any combination thereof. In some embodiments, nanoparticles can be produced as bicomponent segmented pie and islands-in-a-sea. The filaments are then stretched to obtain submicron filaments. The continuous filament nanofibers are cut to the desired length, preferably about 100 to about 10,000 microns.

[0025] 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 submicron fiber nonwoven fabric into a shredder or grinder or edge trimmer machine where the bonded nonwoven fabric goes in and short cut fibers come out. For example, low mass biocomponent meltblown or nano meltblown fibers can be fed into a shredder to obtain submicron nanoparticles. In some embodiments, different nanoparticles may be mixed. For example, nanofibers and nanobeads can be mixed. Two different nanofibers with different melting points can also be mixed, such that a low melting point nanoparticle acts as a binder for a high melting point nanofiber. Similarly, nanoparticles with different diameters and lengths can also be mixed. In some embodiments, the nanoparticles are selected from environmentally sustainable sources. The nanoparticles may be biosoluble glass nanofibers, biodegradable nanoparticles, compostable nanoparticles, or recyclable compositions.

[0026] Different types of nanoparticles can be combined. Some of the nanoparticles can be functional nanoparticles. For example, the functional nanoparticles can include activated carbon and / or antibacterial materials deposited and / or attached to the fibers in the fibrous material. This can improve the gas absorption efficiency and bacteria killing effect of the fibers. Also, the nonwoven product of microfiber nonwoven fabrics deposited with glass and carbon nanoparticles can provide filtering and odor removal functions as a filter medium. In some embodiments, the nanoparticles are attached to the fibers through mechanical entanglement. This mechanical adhesion can be supplemented with adhesives and / or binders, as discussed in more detail below. In certain embodiments, the nanoparticles are not crimped (i.e., do not contain significant wavy, bent, curled, coiled sawtooth, or similar shapes associated with nanoparticles in a relaxed state). In other embodiments, the nanoparticles can have a crimped structure with discrete lengths. For example, when these crimped nanofibers with discrete lengths are attached to the fibers, they become anchored and entangled with themselves, on, and around the fibers to form modified fibers. In other embodiments, the attachment of the nanofibers to the micron fibers is achieved through electrostatic charge attraction and / or van der Waals forces between the fibers and the nanoparticles.

[0027] Filter media and filters, such as air filters, face masks, gas turbine and compressor intake filters, panel filters, and the like, are also provided, which include nanoparticles distributed in depth within the filter media. In some embodiments, the filters include one or more support layers attached to the filter media. The support layers and / or filter media may include nanoparticles distributed in depth within the layer. In some embodiments, polymer layers, membranes, or films are provided that include one or more openings for gas or liquid flow, in which the nanoparticles are disposed in depth within the polymer layer. In other embodiments, the fibrous material constitutes a flexible surface layer for finger bandage pads, face masks, and the like. Provided herein are systems, devices and methods for manufacturing fibrous materials and products (e.g., gas filters) that include fibrous materials. Systems and methods are also provided for singulating individual nanoparticles in gaseous media, such as air, helium, nitrogen, oxygen, carbon dioxide, etc. (instead of liquids), which can be dispersed into another product, film, layer, or substrate via gas flow, aerosol, vaporizer, sprayer, or other suitable delivery mechanism.

[0028] Although the following description is presented primarily with respect to fibrous materials and filter media, it should be understood that the devices and methods disclosed herein can be easily adapted for use in a variety of other applications. For example, the fibrous materials disclosed herein can be useful in household cleaning products, roofing and flooring products, automotive interiors and headliners, reusable bags, wallpaper, filtration devices, insulation, and the like. Furthermore, the individual nanoparticles singulated and produced by the processes described herein can be utilized in various coatings, composites, and / or additives in, for example, polymers, food packaging, flame retardants, fuel cells, batteries, capacitors, nanoceramics, lighting, materials manufacturing, manufacturing methods, composite reinforcement, cement and other materials, medical diagnostic applications, medical treatment devices or therapies, 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 therapy delivery, environmental applications such as biodegradable compounds, and the like.

[0029] FIG. 1 illustrates a fibrous material or substrate 10 including a plurality of fibers 12 and nanoparticles 14. The substrate 10 has a first surface 16 and a second surface 18 opposite the first surface 16, defining a width or thickness between the first and second surfaces 16, 18. Nanoparticles 14 are deposited on the substrate through the first surface 16. As shown, the nanoparticles 14 penetrate through the first surface 16 and "into" 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 have been broken down, separated, and singulated from one another prior to dispersion in the substrate 10 (as shown in FIG. 24B). Thus, the nanoparticles 14 are not layered in the fibrous product and do not have significant clumps or bundles of nanofibers (as shown in FIG. 24A). This results in greater nanoparticle dispersion throughout the substrate, which in some applications, such as gas filters, provides more efficient filtration capacity for filtering contaminants. Furthermore, this results in a fibrous material with a greater nanoparticle areal density (grams per square meter (gsm)) or "loading" within the material. The term "loading" is used herein to mean the areal density (gsm) of material, fibers, or particles in a thin layer, sheet, or film of material. In certain embodiments, the nanoparticles have a density of about 0.1 grams / m 2 ~ approx. 20 grams / m 2 , preferably at least about 2.0 grams / m 2 The specific loading or areal density may vary depending on the application. For example, applicants have found that the higher the areal density or loading, the more efficient the fibrous material is at filtering contaminants. Thus, the specific loading of nanoparticles may vary depending on the desired efficiency of the filter media.

[0030] FIG. 2 illustrates a fibrous material or substrate 20 including a plurality of fibers 12 and nanoparticles 14. As shown, the nanoparticles 14 permeate the entire width of the substrate 20 from the first surface 16 to the second surface 18. In certain embodiments, the nanoparticles 14 are dispersed substantially throughout the fibers 12 of the substrate as shown in FIG. 2. In certain embodiments, the density of nanoparticles located at the first surface 16 differs by less than 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 to create 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 with a higher density of nanoparticles 14 located near the first surface 16 than at the second surface 18. In certain embodiments, the density of the nanoparticles located at the first surface 16 differs from the density of the nanoparticles dispersed at the second surface 18 by more than about 75%. In some embodiments, the difference is greater than 50%. In some embodiments, the difference is greater 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.

[0031] 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., a general decrease in density that is neither linear nor step-like). In other embodiments, nanoparticles may be loaded onto the substrate from both the first and second surfaces 16, 18. In these embodiments, the area density or "loading" 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 "loading" present at the center of the substrate is lower than that at 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%.

[0032] The distribution of nanoparticles through the thickness of the fibrous material can be measured, for example, using imaging techniques. Using electron microscopy or other techniques, a close-up of the fibrous product taken at the center of the thickness of the product in a horizontal cross-section of the product can be compared to an image taken at the top or bottom of the product, or all three images can be compared to determine how much the nanoparticle deposition varies. Computer image analysis processes can be employed. For example, in FIG. 3, a cross-section AA can be taken and a cross-section BB can be taken. The top-view images of each cross-section can be taken by electron microscope, scanning electron microscope, or other microscope. For example, the top-view image of the cross-section taken at the AA cross-section can be compared to the top-view image taken at the BB cross-section. 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 fiber orientation and other characteristics. These techniques can be used to determine whether nanoparticles are deposited in the depth direction of the substrate, across a substantial portion of the substrate, to substantially the entire depth, or to a portion of the substrate depth.

[0033] The fibers of the contemplated substrates may be made by any method including, but not limited to, airlaid, spinneret, gel spinning, melt spinning, wet spinning, dry spinning, island-in-a-seat staple or spunbond, segmented pie staple or spunbond, and others. Such methods are described in U.S. Patent 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 Publication No. 2009 / 266,759, the entire disclosures of which are incorporated herein by reference for any purpose. Contemplated fibers may have many cross-sectional shapes, including, but not limited to, round, kidney bean, dog bone, trefoil, barbell, bowtie, star, Y-shaped, and others. These shapes and / or other conventional shapes may be used in conjunction with these embodiments to obtain desired performance characteristics. The fibers in the substrate remain connected to one another, such as by thermal bonding, chemical bonding, intertwining with one another, using a binder such as an adhesive, and the like.

[0034] 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, copolyamide, polyethylene, high density polyethylene ("HDPE"), LLDPE, cross-linked polyethylene, polycarbonate, polyacrylate, polyacrylonitrile, polyfumaronitrile, polystyrene, styrene maleic anhydride, polymethylpentene, cycloolefin copolymers or fluorinated polymers, polytetrafluoroethylene, perfluorinated ethylene and hexyfluoropropylene, or copolymers with PVDF such as P(VDF-TrFE) or P(VDF). -TrFE-CFE), terpolymers, propylene, polyimides, polyetherketones, cellulose esters, nylons and polyamides, polymethacrylics, poly(methyl methacrylate), polyoxymethylene, polysulfonates, acrylics, styrenated acrylics, preoxidized 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, styrene, or any combination thereof. Other conventional fiber materials are also contemplated.

[0035] The fibers can include fibers of different sizes, and the fibers generally have diameters ranging from about 1 to about 1000 microns and lengths ranging from about 0.5 to 3 inches. The fibers may be configured as a gradient density medium with decreasing pore size from the top (upstream) to the bottom (downstream) of the filter to increase capture efficiency and dust retention capacity. This configuration also allows different amounts of nanoparticles to be dispersed at different depths of the filter media. For example, the upstream side of the filter media can have the largest fiber size to allow for more voids and a higher density of nanoparticles, while the downstream side of the filter media can have smaller sized fibers to provide a lower density of nanoparticles. Alternatively, this configuration can be reversed to provide a higher density of nanoparticles in the downstream portion of the filter media. Fibers in the media may remain connected to other fibers by being thermally bonded, chemically bonded, or intertwined with one another. Bicomponent fibers are sometimes used especially in mechanical filtration and 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), etc.

[0036] In some embodiments, the substrate may comprise a "high loft" nonwoven material, including spunbond or air-through bond carded nonwoven fibers. As used herein, the term "high loft" means that the volume of voids is greater than the volume of all solids. With air-through bond 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 increased by reducing the compressive force exerted on the medium during bonding. In another example, high loft nonwoven materials may be produced using thicker fibers, such as greater than 3 denier, e.g., 5 denier or greater, 6 denier or greater in thickness (discussed in more detail below). In other embodiments, loft may be increased 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 contaminants 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 may include an amino-functional polydimethylsiloxane and / or a polyethylene glycol monotridecyl ether. Suitable silicone coatings are described in commonly assigned U.S. Provisional Patent Application No. 63 / 406,686, filed September 14, 2022, the entire disclosure of which is incorporated herein by reference.

[0037] The filter media may include charging additives to modify the triboelectric charging of the fibers and increase the stability and / or duration of triboelectric charging within the filter. This increases the overall filtration efficiency of the filter without compromising other important properties of the filter, such as the life, dust holding capacity, and pressure drop or air flow rate of the filter. Suitable charging additives for triboelectric charging are described in commonly assigned Provisional Patent Application No. 63 / 410,731, filed September 28, 2022, the entire disclosure of which is incorporated herein by reference for any purpose. The fibers can have a thickness suitable for the application. In some embodiments, these fibers have at least one dimension in the range of about 1 to about 10,000 micrometers, or about 1 to about 1,000 micrometers, or about 10 to about 100 micrometers. The thickness of the fibers can also be measured in denier, which is a measure of the linear mass density of the fiber. In some embodiments, the fibers can 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 nanometers, or about 1 to about 100 nanometers. The above dimensions of the fibers and nanoparticles can be diameter or width, depending on the shape of the fiber or nanoparticle.

[0038] 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 having the same or different linear densities. Air filter fibers generally have a linear density of about 3 denier or less to ensure that the fibers are small enough to capture contaminants passing through the filter. Applicant has surprisingly discovered that by using nanoparticles dispersed in the filter media, the fibers can have a greater linear density, for example, greater than 3 denier. This is because the nanoparticles provide significant filtering capacity. In some cases, the fibers can have a linear density greater than 3 denier, greater than 5 denier, greater than 6 denier, or even 7-10 denier.

[0039] Applicant has also discovered that in some applications, fibers having a greater linear density than those used in conventional filters (e.g., greater than about 3 denier) provide more open space or pores within the filter media, which allows for a greater density of nanoparticles to be dispersed therein. Although this may be contrary to common knowledge to those skilled in the art, Applicant has discovered that fibers having a greater linear density incorporating nanoparticles actually improve the overall efficiency of the filter. In certain embodiments, the filter medium may include at least two different fiber thicknesses or linear densities to provide at least two different filter layers within the same filter medium. For example, in some cases, one portion of the filter medium includes fibers with a linear density greater than 3 denier, such as 5 denier or more or 6 denier or more. Another portion of the filter medium includes fibers with a more standard linear density of 3 denier or less. This dual-layer filter medium forms a first filter portion that primarily filters contaminants with nanoparticles with a high density in the thicker fibers, and a second filter portion that primarily filters contaminants with fibers with a lower linear density, although both portions may include nanoparticles dispersed throughout the fibers. In certain embodiments, the filter medium may include three or more separate portions or layers with different denier fiber ranges within each portion.

[0040] FIG. 4 shows a dual layer filter medium 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 adhered to the second substrate 54 by any method known to those skilled in the art. The first substrate 40 includes fibers 46 having a relatively low linear density, e.g., on the order of 3 denier or less. The second substrate 50 includes fibers 56 having a relatively high linear density, e.g., on the order of 3 denier or more, e.g., 5 denier, 6 denier or more. The second substrate 50 also includes individual nanoparticles 58 dispersed throughout, adhered to the fibers 56, and / or retained by the second substrate 50. The first substrate 40 may or may not 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.

[0041] In some embodiments, the substrate may be detrimental to additives such as antimicrobial and / or antiviral compositions, such as silver, zinc, copper, organosilicone, tributyltin, organic compounds containing chlorine, bromine, or fluorine compounds. The fibers may include biocomponent fibers that include two or more different fibers attached to one another. The fibers may comprise the same material or different materials. 5A-5C show various examples of biocomponent fibers that can be used with the fibrous 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 parallel to 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 may include shapes other than circular, such as a dog bone shape, square, triangle, diamond, etc. Alternatively, the fiber may include multiple cores or be divided into three, four or more quadrants.

[0042] In certain embodiments, the fibrous material (i.e., fibers and / or nanoparticles) can be electrostatically charged, for example, so that contaminants are captured by both mechanical and electrostatic filtration. The adhesion 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 the nanoparticles and electrostatic filtration can be achieved by the electret substrate. The electrostatic substrate or electret substrate can be a high-loft triboelectric filter medium made by carding and needling. In one embodiment, the nanoparticles are preferably deposited on the substrate before needling, and then both the electrostatic fibers and the nanoparticles are needled together. The substrate, the nanoparticles, or both can be electrostatically charged using tribocharging, corona discharge, electrostatic fiber spinning, hydrocharging, charging bars, or other known methods. Corona charging is suitable for charging monopolymer fibers or fiber blends, or fabrics. Tribocharging can be suitable for charging fibers of different electronegativities. Electrostatic fiber spinning combines polymer charging and fiber spinning in a one-step process. Suitable charging additives for tribocharging are described in commonly assigned U.S. Provisional Patent Application No. 63 / 410,731, filed September 28, 2022, the entire disclosure of which is incorporated herein by reference for any purpose. Nanoparticles can be selected to have different triboelectric properties relative to the fibers in order to use the triboelectric effect to enhance particle removal. In this way, the nanoparticles produced are formed in an electric field and are less susceptible to contamination by chemicals that may mitigate the triboelectric effect. Nanoparticles with 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. Nanoparticles and coarse fibers can have different wetting properties.

[0043] The fibrous material may include a binder or material, such as an adhesive or binder, to promote adhesion between fibers and / or retention of the nanoparticles within the substrate, such that the nanoparticles may adhere to the fibers or otherwise be held by the fibers within the substrate to form a stable matrix. The binder or material is preferably present in a relatively small amount to adhere the individual nanoparticles to the fibers in the substrate. Binders may include a variety of conventional materials including naturally based materials such as starch, dextrin, guar gum, etc., or synthetic resins such as EVA, PVA, PVOH, SBR, polyglycolide, etc. In certain embodiments, a solvent based adhesive is used, where adhesion 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 combinations thereof.

[0044] In some embodiments, an adhesive resin is used, which may undergo crosslinking after application of the adhesive on the substrate. Adhesion (water / solvent resistance) may be promoted by self-crosslinking as 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, or electron beam. The amount of adhesive may 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 a spray nozzle, dip coating, or other methods. In some embodiments, the binder or bonding material may include a surfactant to reduce the surface or interfacial tension of the binder, thereby enhancing its dispersion and wetting properties and allowing the binder to more easily penetrate the depth of 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 (dioctyl sodium sulfosuccinate), alkyl ether phosphates, benzalkonium chloride (BAC), perfluorooctane sulfonate (PFOS), and the like.

[0045] In some embodiments, the substrate includes its own binder composition. In these embodiments, a binder or binding material may or may not be added to the substrate. In one such embodiment, the substrate includes biocomponent fibers, and one of the components includes an outer sheath at least partially surrounding an inner core (see Figures 5A and 5C). The sheath may comprise a material that adheres to the nanoparticles. For example, the sheath may comprise a material that becomes sticky and / or flowable upon heating and / or drying. During the heating / drying step (described below), the fiber sheath is heated to its melting point until it becomes sticky and / or flowable to adhere the nanoparticles to the substrate. In a preferred embodiment, adhesion and drying occur simultaneously.

[0046] Figure 23A is a magnified image of a fibrous product having nanoparticles deposited therein without the use of a binder material, and Figure 23B is a magnified image of a fibrous product having nanoparticles attached to the fibers using a binder material of dextrin and water. As shown, the nanoparticles are more uniformly attached to the fibers with the use of a binder. In the examples of Figures 23A and 23B, a substrate was used having bicomponent microfibers with an inner polyester and an outer high density polyethylene ("HDPE"). Figure 23A shows a microfiber fibrous product having a bicomponent microfiber substrate with biosoluble glass nanofibers deposited in a layer only on the surface of the substrate and relying on electrostatic forces to hold the nanofibers. Nanofiber clumping and poor nanofiber retention can be seen in Figure 23A. The substrate can be manufactured using meltblown, spunbond, or other methods described herein.

[0047] 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, resulting in increased uniformity and improved retention of the nanofibers. In further examples, any of the binder materials disclosed herein can be used. Additionally, nanoparticles of biosoluble glass are deposited into the substrate in the depth direction. In this example, the bicomponent microfiber substrate itself has a MERV rating in the range of 4-10, which can be achieved using any of the methods described herein. The nanoparticles are deposited into the substrate in the depth direction and electrostatically charged, resulting in a fibrous product with a MERV of 13 in one example, using a microfiber substrate originally with a MERV of 8. In another example, a fibrous product with a MERV of 15 is produced using a microfiber substrate originally with a MERV of 6. The substrate is provided in a roll, and the fibrous 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.

[0048] In certain embodiments, the fibrous materials described herein can 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, surgical masks or other face coverings, etc. The filter device can be a mechanical filter, an absorbent filter, a sequestrant filter, an ion exchange filter, a reverse osmosis filter, a surface filter, a depth filter, etc., and can be designed to remove many different types of contaminants from air, water, etc. In one such embodiment, the fibrous 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 fibrous material may comprise a filter medium for an air filter, may be supported by a support layer, a scrim layer, or may be included in other layers or materials. Applicant has discovered that by incorporating nanoparticles in the depth direction of the fibrous material as described herein, the efficiency of the air filter is substantially increased without compromising other factors such as pressure drop (i.e., airflow) of the filter. Furthermore, these materials improve the overall dust holding capacity and thus the life of the filter, especially compared to filters that rely solely or primarily on electrostatic effects to increase efficiency.

[0049] Traditional residential and commercial air filters, such as HEPA filters, are typically rated by the filter's ability to capture particles between approximately 0.3 and 10 microns in size. This rating, called the Minimum Efficiency Reporting Value, or MERV, was developed by the American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE). MERV ratings range from 1 to 16, with higher numbers indicating greater efficiency in capturing a particular type of particle. Traditional mechanical air filters typically report a MERV rating of approximately 8 for their fibrous filter media. Air filters are generally rated based on their initial efficiency (i.e., the efficiency of the air filter before use) and their efficiency over time. This latter efficiency is generally tested through a conditioning step 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 0.5 inches of water. In some cases, the initial MERV rating is about 11 with a pressure drop of about 0.17 inches of water or less, or an initial MERV rating is about 13 with a pressure drop of about 0.36 inches of water or less, or an initial MERV rating is about 14 with a pressure drop of about 0.5 inches of water or less.

[0050] 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 acceptable standard in the industry. The MERV ratings of the fibrous filter media described herein 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, the number and size of pleats (if any), etc. MERV ratings can be measured not only for fibrous products formed as pleated filter media, but also for sheets of fibrous products, each of which may have different pressure drops. Similarly, the pressure drop of the filter media also depends on many factors, including those mentioned above.

[0051] One factor that affects both MERV rating and pressure drop is the density or loading of nanoparticles in the substrate relative to the density of fibers in the substrate. Applicants have discovered that the lower the ratio of substrate density to 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 nanoparticle density of about 0.1 grams / m 2 ~ approx. 20 grams / m 2 , preferably at least about 2 grams / m2 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 described in more detail below with reference to Table 2, a density ratio of about 67 (gsm of substrate divided by gsm of nanoparticles added) resulted in a pressure drop of about 0.14 inches of water and an initial MERV rating of 10. A density ratio of about 33.4 increased the MERV rating to 10, but only resulted in an increase in pressure drop to about 0.17. A density ratio of about 22.3 increased the initial MERV to about 12, with a pressure drop of about 0.24 inches of water. Thus, the efficiency or MERV rating of the filter increases with increasing nanoparticle loading. In particular, Applicant has determined that the nanoparticle loading is at least 2 g / m 2 They found that a filter with a MERV rating of about 10 could be achieved with a loading of 4 or 6 g / m 2 A loading of 10 g / m results in filters with MERV ratings of approximately 12 and 13, respectively. 2 These dosages will result in a filter with a MERV rating of 15 or higher.

[0052] Applicants have also discovered that including fibers having a thicker thickness or greater linear density results in larger pore size and therefore a larger pore volume, thereby allowing for a higher density of nanoparticles within the substrate. This results in a higher MERV rating and pressure drop (see Table 2 below). For example, Applicants have been able to use 5 denier biocomponent fibers to produce air filters with a MERV rating of 14 and a pressure drop of 0.5 inches of water. Similarly, Applicants have been able to use 5 denier biocomponent fibers to produce filters with a MERV rating of 13 and a pressure drop of only 0.29 inches of water. An example of a pleated filter media 90 is shown in FIG. 6. The filter 90 may include about 0-3.9 pleats per centimeter (about 0-10 pleats per inch) depending on the application. The filter media can be mounted on a cardboard or metal frame for easy replacement filter products (FIG. 7). As shown, a gas filter 94 was made from the fibrous materials described herein. As shown, the filter 94 includes a pleated fibrous filter media 96 and a support layer 98 that provides rigidity and structure to the filter media 96.

[0053] 11 shows a gas filter 109 made from the fibrous materials described herein. The gas filter 109 includes a fibrous substrate that includes fibers and nanoparticles dispersed through the depth of the substrate. The substrate can then be rolled into a cylinder, cone, or other suitable shape and used in applications such as gas turbine and compressor intake filters, panel filters, and the like. Other types of filters that can be developed using the fibrous 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.

[0054] The fibrous products disclosed herein can be used in medical masks or other medical applications such as respirator cartridges. Medical masks are designed to protect medical personnel and / or patients from microorganisms and other substances. 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 mask is made with multiple layers of fibrous material and has ear loops, ties, or other structures for attaching the mask to a person's face. At least the top of the mask can incorporate wires so that at least a portion of it conforms to the person's face. The mask can include a rigid polymer structure designed to hold the multi-layered fibrous material to the front of the person's face. In one example, the mask has three layers. The outer and inner layers include fibrous materials such as spunbond polypropylene that provide breathability, although any of the materials mentioned herein can be used. The middle layer is disposed between the inner and outer layers and includes a microfiber substrate with nanoparticles deposited in the depth direction of the substrate to provide an initial MERV of 8 or more, preferably a MERV of 10 or more, and more preferably a MERV of 13 or more. The pressure drop through the mask is 3-6mm of water, more preferably 4mm of water for breathability. It is desirable for the mask to have an efficiency of about 95%. Other examples of masks have 4 or more layers. Multiple layers of textile products can also be combined into one mask.

[0055] In certain embodiments, the fibrous material can be included in a thin film or layer that includes openings, pores, or perforations. The openings may be embossed with a pattern (circles, diamonds, hexagons, ellipses, triangles, rectangles, etc.) and then stretched until openings are formed in the thinned areas created by the embossing. Such apertured substrates can be formed from many polymers, such as polypropylene, polyethylene, high density polyethylene ("HDPE"). The polymer layer can include, for example, 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 can be formed by the methods described herein. In another embodiment, a gas filter includes a filter media and a substantially rigid support layer adhered to the filter media, the support layer including fibers and individual nanoparticles disposed depthwise within the layer, the nanoparticles configured to filter contaminants passing through the support layer.

[0056] 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 an extruded sheet of a polymer, such as polypropylene film, high density polyethylene film, polylactic acid film, or a thermoplastic polymer material, such as an extrudable fluoroplastic material, in some embodiments, a perfluoroalkoxyalkane (PFA) copolymer made from the comonomers polytetrafluoroethylene and perfluoroalkylvinylether. However, other polymer materials, such as fluoroplastics, e.g., ethylene chlorotrifluoroethyl (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 throughout the depth of membrane 810. The nanoparticles enable the support membrane to filter at least a portion of the contaminants passing 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 supported membranes are designed to direct the fluid to be filtered along their surface while simultaneously directing the fluid through their structure to the underlying filter substrate, removing undesirable particles from the filtrate.

[0057] As shown in Figures 9A and 9B, the support film 810 can 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 can be wound into a roll and then unwound and passed through a punch press to form apertures 828 through in the Z direction in the desired predetermined pattern (Figure 9A). Alternatively, the sheet can be set and then passed through a punch press in a continuous operation to form the predetermined pattern of apertures 828. Referring to FIG. 9B, after opening, the filter support member can be stretched in the machine direction, as indicated by double-headed arrow 940, to expand the opening 828 to provide a larger open area for the passage of fluid to be filtered by the filter media or substrate 812. In another embodiment, the support membrane 810 may be porous (i.e., instead of or in addition to having openings 828). In this embodiment, additional fluid flow can be achieved with a substantially porous support membrane. In an exemplary embodiment, the support membrane has a porosity of at least 0.5 or 50%, preferably at least 0.8 or 80%, more preferably about 0.86 or 86%. Porosity is defined as the volume fraction of non-solid or pores relative to 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 in its entirety for any purpose.

[0058] The filter support membrane can be made 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 can be made by extruding a polymeric material into a sheet and then passing the sheet through a nip area provided by opposing rollers, at least one of which has countersunk grooves on its outer surface. The countersunk grooves of one roller are aligned with the outer surface or countersunk 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 during the extrusion process or known embossing methods. Once the ribs are formed, the support membrane can be wound into a roll and then unwound and passed through a press to form openings through it in the Z direction in a desired predetermined pattern. Alternatively, as best shown in Figure 9A, the support membrane can be set and then passed through a punch press in a continuous operation to form openings in a predetermined pattern. The punch press can be continuously passed through to form openings in a predetermined pattern. Optionally, the support membrane can be stretched in the machine direction (indicated by the double-headed arrow in FIG. 9B), e.g., to stretch the openings to provide a larger open area for the passage of fluid to be filtered by the filter layer or substrate.

[0059] 12 illustrates generally an overall system 110 for producing the fibrous materials and other products described above. As shown, the system 110 includes a feeder 120 for advancing a substrate 130 of fibers or other material 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 underneath the substrate 130 opposite the fiberization system 150. In one embodiment, the feeder 120 includes a winder 122 at a downstream end of the process and an unwinder 124 at an upstream end to continuously wind 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.

[0060] The coater 140 is configured to spray droplets of a binding agent or material, such as an adhesive or other binder, onto the substrate 130 so that the nanoparticles can adhere to the fibers in the substrate 130 and form a stable matrix. The binder is preferably present in a relatively small amount to adhere the individual nanoparticles to the fibers throughout the substrate 130. In a preferred embodiment, the coater 140 includes a spray nozzle sized to produce droplets of adhesive having a diameter of about 20-30 microns to increase the penetration depth of the adhesive through the substrate 130. Of course, the droplet size can be affected by numerous other parameters including 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 a binder or binding material can be accomplished by other coating methods including ultrasonic spraying, dip coating, spin coating, gravure coating, kiss roll coating, screen coating, powder coating, electrostatic coating, sputter coating, or similar coating techniques.

[0061] As mentioned above, binders can include a variety of conventional materials, including 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 adhesion 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 combinations thereof.

[0062] In some embodiments, an adhesive resin is used, which may undergo crosslinking after coating of the adhesive to the substrate 130. Adhesion (water / solvent resistance) may be promoted by self-crosslinking as the solvent in the adhesive formulation evaporates, or by thermal activation during the drying process. For certain adhesives, crosslinking can be achieved by high energy wavelengths of electromagnetic radiation, including but not limited to RF, UV, or electron 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 enhancing its dispersion and wetting properties and allowing the binder to more easily penetrate the depth of 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 (dioctyl sodium sulfosuccinate), alkyl ether phosphates, benzalkonium chloride (BAC), perfluorooctane sulfonate (PFOS), and the like.

[0063] In some embodiments, the spray coater 140 is positioned 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 positioned downstream of the fiberization system 150 so that the binder can be sprayed after the nanoparticles are deposited. In other embodiments, the system 100 includes two spray coaters, one located upstream of the fiberization system 150 and a second spray coater (not shown) located downstream of the fiberization system 150 to coat the substrate 130 with a secondary binder after the nanoparticles are deposited. In some embodiments, there is more than one nozzle head with each spray coater 140. The nozzle heads may be arranged in series, for example, to obtain better uniformity or to increase the spray width of the fibers. Alternatively, the nozzle heads may be arranged in parallel, i.e., across the 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 beneath the substrate 130 opposite the spray coater 140 to increase the 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.

[0064] 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 with the sheath 82 (FIG. 5C). In other embodiments, the core 72 and the sheath 74 may be juxtaposed with one another (FIG. 5B). Of course, other configurations are possible. For example, the core 184 may include shapes other than circular, such as a dog bone shape, a square, a triangle, a diamond, etc. Alternatively, the fiber 180 may include multiple cores or may be divided into three, four or more quadrants. The sheath 64 may comprise a material that adheres to the nanoparticles. For example, the sheath 64 may comprise a material that becomes sticky and / or flowable upon heating and / or drying. During the heating / drying process, the sheath 64 portion of the fiber is heated to its melting point until it becomes sticky and / or flowable to adhere the nanoparticles to the substrate. In a preferred embodiment, adhesion and drying occur simultaneously in the drying apparatus 160.

[0065] FIG. 13 shows a schematic of a fiberization system 150 for converting nanofibers into individual nanoparticles. The term "fiberization," as used herein, means converting (e.g., opening, separating, singulating, and / or individualizing) clusters, clumps, or other groups 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, fiberization system 150 includes a feeder 200, such as a hopper, for introducing large or macro clusters / agglomerates of nanoparticles (see FIG. 14A) into system 150. The feeder 200 may include 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 specific rate, or may be introduced at intervals at a specific rate. Bundled macro clusters of nanoparticles may be broken down prior to introduction into feeder 200. It should be appreciated that the nanoparticles can be introduced to the fiberizer 150 in many different forms. For example, raw nanofibers can be produced as long, discrete fibers. In this form, the nanofibers may be cut to obtain a desired length / diameter ratio.

[0066] The system 150 further includes a separator 210, such as a blender, for separating or breaking down macro-clusters / agglomerates of nanoparticles into smaller clusters / agglomerates of nanoparticles (see FIG. 14B). The feeder 200 transfers the nanofibers to the separator 210 by any mechanical means in a steady-state, continuous manner. The rate of transfer depends on a variety of factors, including 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 certain size to pass through. The separator 210 may include a number of rotatable blades (not shown) designed to rotate about a vertical axis within the housing 212 to separate and release coarse clusters of nanofibers. The blades may have the same or different pitch and camber to sequentially break down or "open" entangled fibers as they pass from the first opening 214 to the second opening 216.

[0067] 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 to move the nanofibers through system 150. In one embodiment, the gas flow is created using 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 move the nanofibers through system 150. The system 150 includes one or more pumps for moving the nanofiber clusters, and thus the individual nanoparticles, through the system. The pumps may include any suitable pump, such as positive displacement, centrifugal, axial, etc. In one embodiment, the first pump 240 includes a first inlet fluidly connected to the air compressor 230 by a first flow path 242 and a second inlet fluidly connected to the separator 210 by a second flow path 244. Compressed air is drawn into the first pump 240, which creates a negative pressure (e.g., vacuum) that draws the nanofiber clusters from the separator 210 into the pump (discussed in more detail below). The system 250 may further include second and third pumps 250, 260, each fluidly connected to an outlet of the first pump 240. In a similar manner, the second and third pumps 250, 260 create a negative pressure that draws the nanofiber clusters through the third flow path 252.

[0068] In a particular embodiment, the pump 240 includes an eductor 300. As shown in FIG. 15, the eductor 300 includes a motive fluid inlet 302 and a nanofiber inlet 304, each of which is connected to an outlet 306 via a flow passage 308. The flow passage 308 includes a convergent inlet nozzle 310, a diffuser throat 312, and a divergent outlet diffuser 314. The high pressure, low velocity air is converted to low pressure, high velocity air, creating the pressure difference required for suction. Based on the Venturi effect and Bernoulli's principle, a primary fluid medium (e.g., compressed air) is used to create a vacuum 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. Returning to FIG. 13, the third flow path 252 includes a junction 254 that splits the third flow path 252 into two separate flow paths that lead to the second and third pumps 250, 260, respectively. The junction 254 preferably includes a surface or wall that is disposed substantially perpendicular to the third flow path 252 to form a T-shaped intersection. The surface may be any surface that faces the flow of nanofibers through the flow path, such as the inner wall of the flow path at the junction, or other change in direction of the inner wall, e.g., curved, vertical, etc. Alternatively, the flow path may include a wall or other surface disposed within the flow path or projecting into the flow path of the fluid pathway. In one embodiment, the flow path includes two separate flow paths that extend to and from the substantially T-shaped junction. The second ejector is configured to draw the nanofibers into the T-junction at a rate sufficient to break apart at least some of the nanofibers. As the nanofiber clusters travel through the third flow path 252, they are propelled against this surface or wall by the negative pressure applied by the second and third pumps 250, 260. This velocity of the nanofibers relative to the junction 254 creates collisions with sufficient kinetic energy to break at least a portion of the nanofiber clusters into smaller nanofiber clusters and / or into individual nanoparticles having at least one dimension less than 1 micron.

[0069] To create the kinetic energy necessary to break down 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 a pressure throughout the system of at least about 100 psi. In certain embodiments, the system 150 further includes fourth and fifth flow paths 262, 264 connecting the outlets of the second and third pumps 250, 260 to 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 574. 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 generate 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 .

[0070] In another embodiment, the vortex is formed without a separate energy source. In this embodiment, the nanofiber clusters 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 of the inlets 284, 285, 286, 287 is angled such that the nanofibers and nanoparticles enter the reactor 270 substantially tangentially to the central tube 275. As the nanofibers and nanoparticles enter the annular chamber 276, their velocity vectors (speed and direction) create vortices within the reactor 270 that cause the nanofibers and nanoparticles to spin around the central tube 275 and rise to the top of the chamber 276. 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. Without interruption, the nanofibers 290 and nanoparticles 292 are blown up from the bottom to the top of the reactor. The vortex within the chamber 276 can further break down (e.g., open, separate, and / or individualize) the nanofiber clusters 590 as they pass through the 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, or the like.

[0071] The system 100 may further include another pump or negative pressure source (see, e.g., FIG. 17) connected to the top outlet 282. This negative pressure draws the fibers 290 through the outlet 282 as they exit the reactor 270. Because the individual nanoparticles 292 are much lighter than the entangled nanofibers 290 that are still clustered together, these individual nanoparticles 292 are drawn into the top inlet 278 of the central tube 275. Meanwhile, the larger and heavier nanofiber clusters 290 that have not yet been broken down are drawn through the top outlet 284. The top outlet 284 may be connected to another pump (not shown) or to the first pump 240. In this way, the nanofiber clusters 290 are sent back through the process to be further broken down, forming 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 the substrate or into a fiber stream (discussed below). The nozzle 220 may include 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 system.

[0072] In certain embodiments, the system 100 includes two or more nozzles coupled to the outlet 280 of the reactor 270. The nozzles may be arranged in any suitable configuration on the substrate, for example, in parallel, in series, in parallel, etc. It will be appreciated that pump 240, or pumps 250, 260, may also feed the nanofiber / air mixture stream directly to nozzle 220 (i.e., bypassing reactor 270). In this embodiment, the pressure within the system is designed to generate sufficient kinetic energy to break down or open up substantially all of the nanofibers into individual nanoparticles such that reactor 270 is not required to separate the nanoparticles from larger clusters of fibers.

[0073] 17, which illustrates another embodiment of a fiberization system 320. 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 ejector 326 is coupled to the outlet of the separator 325 and serves to draw the nanofibers from the separator 325 into the system 320. An air compressor (not shown) is also coupled to the ejector 326 to provide motive fluid, as described above. As in the previous embodiment, the second and third ejectors 330, 340 are connected to the outlet of the first ejector 3326. The nanofibers are drawn from the first ejector 320 and propelled against a surface of the T-intersection 350 to break down at least a portion of the nanofibers into smaller clusters or individual nanoparticles. The second and third ejectors 330, 340 each have an outlet connected to a further T-shaped intersection 360, 370. As above, the nanofibers are propelled against the surface of the T-shaped intersection 360, 370 for further break-up. The T-shaped intersections 360, 370 each are connected to two flow paths that enter the bottom 380 of the reactor. The bottom 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 causes the nanofibers to enter the vortex of the reactor and swirl upwards to the top 390 of the reactor.

[0074] As previously described with reference to FIG. 16, the reactor includes an annular chamber with a central tube with open upper and lower ends connected to a nozzle. Nanofibers that have been sufficiently broken down into individual nanoparticles flow through the open upper end into the central tube for dispersion through the nozzle. Heavier clusters of nanoparticles that have not yet been broken down exit the reactor through one of four separate outlets 392, 394, 396, 398. Ejectors 410, 420 provide the power to draw the nanofibers from the reactor 400, as described above. Each of the outlets 392, 394 is connected to the ejector 410 via a T-shaped intersection 412, and each of the outlets 396, 398 is connected to the ejector 420 via a T-shaped intersection 422. In this case, the nanofibers flow from two channels into one channel as they pass through the intersections 412, 422. The ejectors 410, 420 are connected to T-junctions 430, 440, respectively. As mentioned above, 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 380 of the reactor 400 (via inlets 432, 434, 442, 444), respectively. This allows the nanofibers to be passed back through the reactor 400 for further processing. This process continues until each cluster of nanofibers is completely broken down into nanoparticles and passes through the nozzle through the central tube. 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.

[0075] In certain embodiments, the fiberization system 150 may include a separate control system that monitors the nanofibers to determine when they have broken down into individual nanoparticles suitable for passing through the nozzle. This control system may, for example, simply monitor the pressure of the system to ensure that sufficient pressure is being applied to the nanofibers to break them down into nanoparticles. Alternatively, this control system may include a variety of different sensors located in the system to detect properties of the nanoparticles, such as mass or size. Sensors may be located within the reactor 400, for example, so that the control system can control various parameters of the reactor 400, such as the negative pressure applied to the outlets 392, 394, 396, 398, the speed of the vortex passing around the annular chamber, or the pressure applied to the central tube that draws the nanoparticles into the nozzle. 18 illustrates another embodiment of a system 500 for manufacturing multiple layers of fibrous material. As shown, the system 500 includes first and second unwinders 502, 504 and a single winder 506 for winding first and second substrates 510, 512 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. The first and second unwinders 502, 504 serve to advance the first and second substrates 510, 512 to a process where they are joined to one another and then wound onto the single winder 506, as described below.

[0076] The system 500 includes first and second spray coaters 520, 522 disposed 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 / apparatuses 530, 532 disposed downstream of each spray gun 520, 522. As previously described, the fiberization apparatuses 530, 532 generate individual nanoparticles and disperse the nanoparticles onto the substrates 510, 512. Once the nanoparticles are dispersed on the substrates 510, 512, the two substrates are joined to one another at a junction 540 and advanced downstream together. The two substrates may be glued to one another at this point, or may simply be layered one on top of the other. The system 500 further includes a heating / drying device, such as an IR oven 550, downstream of the junction 540 of the two substrates. The heating / 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.

[0077] In certain embodiments, the nanoparticles are dispersed on both substrates 510, 512. In one such embodiment, the system 500 is designed such that the nanoparticles are dispersed on a first surface of each substrate. The substrates can then be bonded together with the first surfaces facing each other. Alternatively, the first surfaces may be facing away from each other (i.e., bonding the substrates at a second, opposing surface of each substrate). In yet another embodiment, the first surface of the first substrate is bonded to the second surface of the second substrate. 19 illustrates a filter product 700 including a filter media 710 of fibrous material including fibers 722 and nanoparticles 720 dispersed in at least a portion of the filter media 710. As shown, the filter media 710 has a first top surface 712 and a second bottom surface 714. The nanoparticles are dispersed throughout the top surface 712 such that they extend beyond the top surface 712 and 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 openings for allowing gas or fluid to pass therethrough.

[0078] 20 illustrates another filter product 740 that includes a fibrous material filter media 710 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 adhered to a support layer 730. 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 on the inner surfaces 766, 768 of the filter media 762, 764. In another embodiment (not shown), the nanoparticles are dispersed on the outer surfaces 770, 772 of the filter media 762, 764. In yet another embodiment, the nanoparticles 720 can be deposited on the inner surface 766 of the filter media 762 and the outer surface 772 of the filter media 764. In another aspect, a system for producing a fibrous material includes a first device for generating one or more fiber streams and a second device for singulating nanoparticles in a gas medium. The second device disperses the nanoparticles into a stream and feeds the stream into the fiber stream to form the fibrous material. The system may further include a dispersing device, such as a nozzle, coupled to the second device and configured to feed the nanoparticles substantially uniformly into the fiber stream. The fiber stream may be generated by any suitable mechanism known in the art, such as meltblown, spunbond or spunlace, heat bond, carded, airlaid, wetlaid, extrusion, co-molding, needle punch, stitching, hydrodynamic entanglement, etc.

[0079] In one example, the system may include a spunbond line, where filaments are formed by spinning molten polymer and drawing the molten filaments. Fiber bundles of filaments are separated, spread out, and then laid on a net to form a web. The fibers are bonded in the form of a sheet by thermal bonding and embossing. The first stream 630 may be introduced, for example, before the attenuation zone or before the bonding (consolidation) step. In another embodiment, the system may include two carding machines arranged in series with each other. The first stream 630 can 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 fiber webs. Then, all the fibers containing the nanoparticles are bonded together (the nanoparticles are thermally interlocked) in an air-through bonding oven.

[0080] Another embodiment for generating one or more fiber streams is shown in Figure 22. In this embodiment, nanoparticles are dispersed between two meltblowing dies and molten polymer is extruded through small holes to form fibers. When the nanoparticles meet the fibers while still tacky, they mechanically entangle with the fibers and thermally bond to the fibers. Thus, in some embodiments, no additional bonding step is required. 22, an apparatus 600 for forming a fibrous 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 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. This system may include any system known in the art, such as spunbond, carded, extrusion, etc.

[0081] In another embodiment, the apparatus includes first and second feeders, such as 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, it is gradually heated to a molten state by rotation of the extrusion screw by the drive motor. Heating the thermoplastic polymer to a molten state may be accomplished in multiple discrete stages where its temperature is gradually increased as it advances through discrete heating zones of the extruders 650, 652 toward two meltblowing dies 660, 662, respectively. The meltblowing dies 660, 662 may be in yet another heating zone where the temperature of the thermoplastic 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 as it exits the meltblowing die's small holes or orifices 672. The molten yarn 20 is attenuated into small diameter fibers, typically smaller than the diameter of the orifice 672, or into microfibers, depending on the degree of attenuation. Thus, each meltblowing die 660, 662 has a corresponding single primary air stream 680, 690 of gas containing the entrained and attenuated polymeric fibers.

[0082] The primary air flows 680, 690 containing the polymer fibers are aligned to converge at the forming section 700. Additionally, a first stream 630 of individual nanoparticles is added to the two primary air flows 680, 690 of thermoplastic polymer fibers or microfibers at the forming section 30. The introduction of the individual nanoparticles into the two primary air flows 680, 690 of the fibers is designed to create a distribution of secondary fibrous material 32 within the combined primary air flows 680, 690 of the fibers. This can be achieved by merging the first stream 630 of individual nanofibers between the two primary air flows 680, 690 and causing all three gas flows to converge in a controlled manner. Examples of suitable meltblowing dies that may be utilized to produce nonwoven materials are described in more detail in U.S. Pat. Nos. 6,972,104, and 8,017,534 and 7,772,456, and U.S. Patent Application No. US20200216979A1, the entire disclosures of which are incorporated herein by reference in their entireties for any purpose. EXAMPLES

[0083] Example 1 A bicomponent microfiber substrate with an inner circular portion of polyester and an outer concentric portion of HDPE was prepared in a roll. In a roll-to-roll process, the substrate was sprayed with adhesive and nanofibers of biosoluble glass fibers 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 steps 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. In the following examples, a carded air-through bonded nonwoven fabric made from bicomponent fibers is used as the substrate. Flat sheet media samples were tested at a filtration rate of 110 fpm. Sample size was 12 in. x 12 in. (30.48 cm x 30.48 cm). NaCl salt particles ranging from 0.3 to 10 microns were used as the contaminant.

[0084] Example 2 A carded nonwoven fabric made from 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 loadings are controlled by adjusting the line speed. [Table 1] This example shows that by controlling the amount of nanoparticles added, the MERV rating is increased from MERV 7 to MERV 13.

[0085] 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 deposition. Once the solvent evaporates and drying occurs under an IR heater, the starch adheres the nanofibers well. [Table 2]

[0086] Example 4 The substrates used were spunbond or meltblown media with nanoparticles incorporated into the substrate as described herein after IPA discharge. The spunbond fibers were made from molten polymer that was spun and drawn to produce filaments. The substrates had an average basis weight of about 90 gsm and an average thickness of about 0.57 mm. A base sample was used with no nanoparticles incorporated. 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 discharge. In samples 1, 3, and 4, nanoparticles were incorporated into the spunbond fibers after IPA discharge. The test results are shown in Table 3 below. [Table 3] As shown, the efficiency of the nanoparticle-incorporated media samples increased over the base sample for all three particle groups, with significant increases seen 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 when nanoparticles were used. The base sample without nanoparticles had a pressure drop of 0.07 inches of water. Samples 1-4 had a slight increase in pressure drop ranging from 0.17-0.41 inches of water. Sample 2, where nanoparticles were incorporated into the meltblown fibers, had a MERV rating of 14 and a pressure drop of 0.24 inches of water.

[0087] Example 5 5 denier air-through carded fiber was used as the substrate. A base sample was used without nanoparticles incorporated. Two separate samples were prepared with nanoparticles incorporated into the substrate as described herein. The results of this test are shown in Table 4 below. [Table 4] As shown, the efficiency of the nanoparticle-incorporated filter media samples 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 had a pressure drop of 0.0762 cm (0.03 inches) of water. Samples 1 and 2 had a slight increase in pressure drop ranging from 0.7874 to 0.8382 cm (0.31 to 0.33 inches).

[0088] Example 6 Meltblown fibers were used as the substrate. The substrate had an average basis weight of about 24 gsm and an average thickness of about 0.4 mm. A base sample was used that did not incorporate adhesives such as nanoparticles or PVOH. Sample 1 included meltblown fibers with the belt side up. PVOH was sprayed onto the fibers, but no nanoparticles were incorporated. Sample 2 included meltblown fibers with the fuzzy side up. PVOH was sprayed onto the fibers, but no nanoparticles were incorporated. Sample 3 included meltblown fibers sprayed with PVOH and with nanoparticles incorporated into the fibers as described herein. The results of this testing are shown below in Table 5. [Table 5] As shown, the efficiency of Sample 3 incorporating nanoparticles was increased over the other three base samples for all three particle groups, especially the E1 particle group. The total MERV rating of Sample 3 increased from MERV 13 or 14 (base samples) to MERV 15 when nanoparticles were used. The PVOH added 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 0.40 inches of water to 1 inch of water. Sample 3, where nanoparticles were incorporated into the meltblown fibers, had a MERV rating of 15 and a pressure drop of 1.02 inches of water.

[0089] Example 7 A 5 denier air-through carded fiber was used as the substrate. A base sample was used that did not incorporate nanoparticles. Seven additional samples were prepared that included 5 denier carded fiber with nanoparticles incorporated into the substrate as described herein. The results of this testing are shown 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 groups, especially for the E2 and E3 particle groups. The total MERV rating increased from MERV 6 (base sample) to MERV 7-MERV 13 with nanoparticles. The pressure drop only increased from 0.0762 cm (0.03 inches) of water to a maximum of 0.8128 cm (0.32 inches) of water.

[0090] Example 8 High loft spunbond fiber was used as the substrate on the continuous fiber line. Two different versions were included in this test: 205-6 and 205-2, and the continuous fiber line setup was altered to prepare two substrates with different masses and thicknesses. For each version (205-6 and 205-2), a base sample was used that did not incorporate nanoparticles. Six additional samples were prepared containing 205-6 and 205-2 fibers with nanoparticles incorporated into the substrate as described herein. The results of this test are shown in Table 7 below. [Table 7] As shown, the efficiency of the six samples incorporating nanoparticles was substantially improved over the base sample for all three particle groups. The total MERV rating increased from MERV 6 (base sample) to MERV 11-MERV 14 with nanoparticles. The pressure drop only increased from 0.04 inches of water to a maximum of 0.87 inches of water. The pressure drop for the 205-2 sample only increased to a maximum of 0.48 inches of water.

[0091] Example 9 Spunbond and meltblown fibers were used as substrates. The average basis weight of the substrates was about 70 gsm for the spunbond fibers and about 24 gsm for the meltblown fibers. The average thickness of the substrates was about 0.75 mm. A base sample was used that did not incorporate nanoparticles. Five additional samples were prepared that included spunbond and meltblown fibers with nanoparticles incorporated into 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. Additionally, in Samples 1 and 2, the substrates were not sprayed with the adhesive PVOH. Samples 3-5 were sprayed with PVOH. The test results are shown in Table 8 below. [Table 8] As shown, the efficiency of the five samples incorporating nanoparticles was substantially improved over the base sample for all three particle groups. The total MERV rating increased from MERV 5 (base sample) to MERV 16 with nanoparticles. The pressure drop only increased from 0.07 inches of water to a maximum of 0.56 inches of water. For samples 3-5 (PVOH sprayed on substrate), the pressure drop only increased to a maximum of 0.4 inches of water.

[0092] Example 10 Five denier air-through carded glass fiber was used as the substrate. 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 test results are shown in Table 9 below. [Table 9] As shown, the efficiency of the three samples incorporating nanoparticles was substantially improved over the base sample for all three particle groups. The total MERV rating increased from MERV 6 (base sample) to MERV 12 or MERV 13 when nanoparticles were used. The pressure drop only increased from 0.03 inches of water to a maximum of 0.27 inches of water.

[0093] Example 11 A fiber blend of 5 denier and 7 denier air-through carded glass fiber was used as the substrate. The media was air-through bonded. A base sample was used that did not incorporate nanoparticles. Nineteen additional samples were prepared that included a fiber blend of 5 denier and 7 denier carded glass fiber that incorporated nanoparticles. The test results are shown in Table 10 below. [Table 10] As shown, the efficiency of all 19 samples incorporating nanoparticles was substantially improved over the base sample for all three particle groups. The overall MERV rating increased from MERV 6 (base sample) to MERV 10-MERV 13 with nanoparticles (the majority of samples were rated MERV 13). Pressure drop only increased from 0.03 inches of water to a maximum of 0.31 inches of water.

[0094] Although the devices, systems, and methods have been described in detail herein in accordance with certain preferred embodiments thereof, numerous modifications and variations therein may be made by those skilled in the art, and therefore the foregoing description should not be construed as limited thereby, but rather should be construed as including such obvious modifications of the foregoing, and only as limited by the spirit and scope of the following claims.

[0095] For example, in a first aspect, a first embodiment is a gas filter that includes a first fibrous layer, a second fibrous layer adhered to the first layer, and a plurality of nanoparticles incorporated into the first layer. A second embodiment is the first embodiment, wherein the first layer has a first surface and a second surface opposite the first surface, and the nanoparticles are disposed from the first surface into an internal structure of the first layer between the first surface and the second surface. A third embodiment is any combination of the first two embodiments, wherein said nanoparticles are incorporated throughout substantially the entire first layer, from the first surface to the second surface. A fourth embodiment is a combination of any of the first three embodiments, where the second layer is adhered to the first surface of the first layer. A fifth embodiment is a combination of any of the first four embodiments, where the second layer is adhered to the second surface of the first layer. A sixth embodiment is any combination of the first five embodiments, further comprising a plurality of nanoparticles incorporated into the second layer. A seventh embodiment is any combination of the first six embodiments, wherein the first layer and the second layer each have a first surface and an opposing second surface, and the second surface of the first layer is adhered to the first surface of the second layer.

[0096] An eighth embodiment is any combination of the first seven embodiments, wherein said nanoparticles are dispersed on the second surface of the first layer and on the first surface of the second layer. A ninth embodiment is any combination of the first eight embodiments, wherein said nanoparticles form a density gradient from the first surface to the second surface of the first layer. A tenth embodiment is any combination of the first nine embodiments, wherein the fibers of the first layer have a linear density greater than about 3 denier. An eleventh embodiment is the tenth embodiment, wherein the fibers of the first layer have a linear density greater than about 5 denier. A twelfth embodiment is any combination of the first eleven embodiments, wherein the fibers of the first layer have a linear density greater than about 6 denier. A thirteenth embodiment is any combination of the first twelve embodiments, wherein the fibers of the second layer have a linear density of about 3 denier or less. A fourteenth embodiment is any combination of the first thirteen embodiments, where the first layer is laminated to the second layer.

[0097] A fifteenth embodiment is any combination of the first fourteen embodiments, wherein the fibers of the first layer comprise a static charge. A sixteenth embodiment is any combination of the first fifteen embodiments, wherein the fibers of the first layer are biocomponent fibers having a core and a sheath, said core and sheath being eccentric. A seventeenth embodiment is any combination of the first sixteen embodiments, further comprising a binder within the substrate to adhere the nanoparticles to the fibers, the binder comprising a material selected from the group consisting of starch, dextrin, guar gum, PVOH, and synthetic resins. An eighteenth embodiment is any combination of the first seventeen embodiments, further comprising a bonding composition that adheres the nanoparticles to the fibers of the first layer. A nineteenth embodiment is any combination of the first eighteen embodiments, wherein the fibers of the first layer have a linear density of about 7 denier and the fibers of the second layer have a linear density of about 5 denier. A twentieth embodiment is any combination of the first nineteen embodiments, wherein the MERV rating is at least 13 and the pressure drop is no greater than 0.31 inches of water.

[0098] In another aspect, a first embodiment is a method for making a filter media, the method including providing a first layer and a second layer, each layer including fibers, dispersing nanoparticles on a first surface of the first layer such that the nanoparticles permeate at least the first surface of the first layer, and adhering the first layer to the second layer to form the filter media. A second embodiment is the first embodiment, further comprising dispersing nanoparticles on the first surface of the second layer such that the nanoparticles permeate at least the first surface of the second layer. A third embodiment is any combination of the first two embodiments, further comprising adhering the first surface of the first layer to the first surface of the second layer. A fourth embodiment is any combination of the first three embodiments, further comprising adhering a second surface of the first layer opposite the first surface of the first layer to a second surface of the second layer opposite the first surface of the second layer. A fifth embodiment is any combination of the first four embodiments, further comprising adhering a first surface of the first layer to a second surface of the second layer opposite the first surface of the second layer. A sixth embodiment is any combination of the first five embodiments, wherein the second layer is a support layer, said support layer being adhered to the first surface of said layer. A seventh embodiment is a combination of any of the first six embodiments, wherein the second layer is a scrim layer and said support layer is adhered to the first surface of the layer.

[0099] An eighth embodiment is any combination of the first seven embodiments, further comprising singulating the nanoparticles in a gas medium, the nanoparticles having at least one dimension less than 1 micron. A ninth embodiment is any combination of the first eight embodiments, further comprising dispersing said nanoparticles substantially throughout the first layer and the second layer to form a composite material. A tenth embodiment is any combination of the first nine embodiments, wherein the nanoparticles form a gradient within the first layer such that the density of the nanoparticles decreases from a first surface of the first layer to a second surface opposite the first surface. An eleventh embodiment is any combination of the first ten embodiments, further comprising applying suction to a second surface of the first layer opposite the first surface to draw the individual nanoparticles through the first layer. A twelfth embodiment is any combination of the first eleven embodiments, further comprising applying a binder to the fibers in the first layer. A thirteenth embodiment is any combination of the first twelve embodiments, wherein the bonding agent is a polymer adhesive, further comprising crosslinking the adhesive. A fourteenth embodiment is any combination of the first thirteen embodiments, further comprising laminating the first layer to the second layer.

[0100] In another aspect, a first embodiment is a system for manufacturing a filter media, the system including a feeder for advancing a first fibrous layer from an upstream end to a downstream end, a dispersing device between the upstream end and the downstream end for dispersing nanoparticles onto a first surface of the first layer such that the nanoparticles penetrate at least the first surface of the first layer, and a device for adhering the first layer to a second fibrous layer. The second embodiment is the first embodiment, further including a second feeder for advancing a second fibrous layer. A third embodiment is any combination of the first two embodiments, further comprising a second dispersing device for dispersing the nanoparticles on the first surface of the second layer such that the nanoparticles penetrate at least the first surface of the second layer. A fourth embodiment is any combination of the first three embodiments, where the first supply device and the second supply device are configured such that the first surface of the first layer is adhered to the first surface of the second layer. A fifth embodiment is any combination of the first four embodiments, where the first supply device and the second supply device are configured such that a second surface of the first layer opposite the first surface of the first layer is adhered to a second surface of the second layer opposite the first surface of the second layer.

[0101] A sixth embodiment is any combination of the first five embodiments, where the first supply device and the second supply device are configured such that a first surface of the first layer is adhered to a second surface of the second layer opposite the first surface of the second layer. A seventh embodiment is any combination of the first six embodiments, further comprising a fiberizer for separating or singulating the nanoparticles in a gaseous medium. An eighth embodiment is any combination of the first seven embodiments, further comprising a coating device for dispersing adhesive on the fibers of the first layer. A ninth embodiment is any combination of the first eight embodiments, wherein the coating apparatus includes a spray apparatus having an outlet and a nozzle adjacent the upstream end of the feed apparatus. A tenth embodiment is any combination of the first nine embodiments, wherein the delivery device includes a first surface and an opposing second surface, the first layer is advanced along the first surface, and the system further includes a negative pressure source adjacent the second surface.

[0102] An eleventh embodiment is any combination of the first ten embodiments, wherein the fibers of the first layer have a thickness greater than about 3 denier. A twelfth embodiment is any combination of the first eleven embodiments, wherein the fibers of the first layer have a thickness of at least about 5 denier. A thirteenth embodiment is any combination of the first twelve embodiments, wherein the fibers of the first layer have a thickness of at least about 6 denier. A fourteenth embodiment is any combination of the first thirteen embodiments, wherein the fibers of the second layer have a thickness of 3 denier or less.

Claims

1. The first fiber layer; A second fiber layer bonded to the first layer; and Multiple nanoparticles incorporated into the first layer A gas filter that includes a gas filter.

2. The filter according to claim 1, wherein the first layer has a first surface and a second surface opposite to the first surface, and the nanoparticles are arranged on the first surface and in the internal structure of the first layer between the first surface and the second surface.

3. The filter according to claim 2, wherein the nanoparticles are incorporated substantially throughout the first layer from a first surface to a second surface.

4. The filter according to claim 2, wherein the second layer is bonded to the first surface of the first layer.

5. The filter according to claim 2, wherein the second layer is bonded to the second surface of the first layer.

6. The filter according to claim 1, further comprising a plurality of nanoparticles incorporated in a second layer.

7. The filter according to claim 6, wherein the first layer and the second layer each have a first surface and a second surface opposite to it, and the second surface of the first layer is bonded to the first surface of the second layer.

8. The filter according to claim 7, wherein the nanoparticles are dispersed on the second surface of the first layer and the first surface of the second layer.

9. The filter according to claim 1, wherein the fibers of the first layer have a linear density of more than approximately 3 denier.

10. The filter according to claim 1, wherein the fibers of the first layer have a linear density of more than about 5 denier.

11. The filter according to claim 1, wherein the fibers of the first layer have a linear density of more than about 6 denier.

12. The filter according to claim 1, wherein the fibers of the second layer have a linear density of about 3 denier or less.

13. The filter according to claim 1, wherein the fibers of the first layer have a linear density of about 7 denier, and the fibers of the second layer have a linear density of about 5 denier.

14. The filter according to claim 13, wherein the MERV rating is at least 13 and the pressure loss is 0.762 cm (0.31 inches) or less for water.

15. The filter according to claim 1, wherein the fibers of the first layer contain an electrostatic charge.

16. The filter according to claim 1, further comprising a binder in the substrate for adhering 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.

17. A system for manufacturing filter media, A feeding device for advancing the first fiber layer from the upstream end to the downstream end; A dispersion device between an upstream and a downstream end for dispersing nanoparticles on a first surface of a first layer such that the nanoparticles penetrate at least the first surface of the first layer; and Apparatus for bonding the first layer to the second fiber layer A system that includes this.

18. The system according to claim 17, further comprising a second dispersion device for dispersing nanoparticles on the first surface of a second layer such that the nanoparticles penetrate at least the first surface of the second layer.

19. The system according to claim 18, wherein the first supply device and the second supply device are configured such that the first surface of the first layer is adhered to the first surface of the second layer.

20. The system according to claim 18, wherein the first supply device and the second supply device are configured such that the second surface of the first layer opposite to the first surface of the first layer is bonded to the second surface of the second layer opposite to the first surface of the second layer.

21. The system according to claim 18, wherein the first supply device and the second supply device are configured such that the first surface of the first layer is bonded to the second surface of the second layer opposite to the first surface of the second layer.

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