Filter media and filter

Abstract

Filter media and filters, such as air filters, household air filters, commercial air filters, masks, gas turbine and compressor intake filters, panel filters, and the like, are provided that include a plurality of fibers having a polysiloxane-based coating. The polysiloxane-based coating includes at least about 2% of a polysiloxane compound by weight of the coating. The polysiloxane-based coating may include an emulsion of active polysiloxane coarse droplets and a surfactant. The polysiloxane-based coating improves the efficiency of the filter to capture contaminants, particularly contaminants in the range of E2 and E3 particle populations, but does not compromise other important characteristics of the filter, such as the cost, life, dust holding capacity, and pressure drop or air permeability of the filter.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims the benefit of U.S. Provisional Application Serial No. 63 / 406,686, filed on September 14, 2022, the entire disclosure of which is incorporated herein by reference for all purposes. Technical Field

[0003] The present description relates generally to filter media having improved performance characteristics and, more particularly, to gas filters incorporating a silicon-based coating that increases the efficiency of the filter in capturing contaminants. Background Art

[0004] Liquid and gas filters capture many different types of contaminants in air, water, or other substances. For example, air filters typically include a filter medium that contains fibers or porous materials that remove solid particles such as dust, pollen, mold, and bacteria from the air.

[0005] The two main types of air filtration devices include 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 sub-micron pore sizes and a narrow pore size distribution. Surface filters tend to have relatively high particle capture efficiencies. However, they also have relatively high pressure drops and low dust loading capacities. High pressure drops result in reduced airflow through the filter. Low dust loading capacities significantly reduce filter life. As a result, surface filters have limited applications in the air filtration industry.

[0006] Depth filters are commonly used in air filtration devices and have medium to high efficiency, low pressure drop, and relatively high dust loading capacity. Depth filters typically use a variety of fibers formed into a mesh or other nonwoven structure that has a tortuous path between the fibers through which a gas stream such as air passes. Particulate matter in the gas flowing through the path of the mesh is trapped on the upstream side of the mesh or within the tortuous path of the mesh due to the particle size relative to the path diameter.

[0007] Traditional home and commercial air filters, such as HVAC filters, are typically rated based on the filter's ability to capture particles ranging from approximately 0.3-10 microns. This rating is called the Minimum Efficiency Reporting Value, or MERV, and is established by the American Society of Heating, Refrigerating, and Air-Conditioning Engineers (ASHRAE). MERV ratings range from 1-16, with higher values ​​indicating greater efficiency in capturing a particular type of particle. It is also common to compare efficiency values ​​based on the size of particles in the airstream during testing. The E3, E2, and E1 values ​​refer to particle efficiencies of 3-10 microns, 1-3 microns, and 0.3-1 microns, respectively.

[0008] In order to improve the efficiency of such air filters in capturing particulate pollutants, chemical treatments, additives or coatings may be applied to the fibers before or after the filter media is formed. For example, the coating may be applied by spraying, dipping, foaming or other known manufacturing techniques. For example, silicon-based coatings have been applied to the fibers to improve the efficiency of the filter media. For example, U.S. Pat. No. 10,279,290 describes such coatings. In another example, as described in U.S. Pat. No. 8,057,583, after the filter media is formed, a polysiloxane and / or wax additive is added to its outermost surface. SUMMARY OF THE INVENTION

[0010] In order to provide a basic understanding of some aspects of the claimed subject matter, a simplified summary of the claimed subject matter is presented below. This summary is not an extensive overview of the claimed subject matter. It is neither intended to identify the key elements of the claimed subject matter nor to delineate the scope of the claimed subject matter. Its sole purpose is to introduce some concepts of the claimed subject matter in a simplified form as a prelude to the more detailed description presented later.

[0011] Filter media and filters, such as gas or liquid filters, masks, CPAP filters, vacuum bags, cabin air filters, HVAC filters, home air filters, commercial air filters, gas turbine and compressor air intake filters, panel filters, etc., are provided, which include fibers having a polysiloxane-based coating. Systems and methods for making such filter media and filters are also provided.

[0012] In one aspect, the filter media includes a layer containing one or more fibers coated with a polysiloxane-based coating. The polysiloxane-based coating comprises at least about 2% of the total weight of the coating. Applicants have found that directly coating the fibers with the polysiloxane-based coating described herein greatly improves the efficiency of such filters in capturing pollutants, particularly pollutants within the E2 and E3 particle group range. In addition, such coatings do not substantially compromise other important properties of the filter, such as the cost, life, dust holding capacity, and pressure drop or air permeability of the filter.

[0013] The fiber structure has a tortuous pore path due to the stacking of fiber webs. In other words, the pore shape of the nonwoven fabric is not cylindrical. Generally, the airflow during the filtering operation passes through the thickness of the filter medium. Therefore, when the contaminants passing through the filter medium hit the fiber surface, they are either captured by the fiber or bounced back. The filter disclosed herein reduces the amount of particles that bounce off the fiber surface and keeps more particles in contact with the fiber surface, resulting in a greater particle capture.

[0014] In an embodiment, the polysiloxane-based coating comprises a polysiloxane compound diluted in water or other suitable fluid such that the polysiloxane compound comprises at least about 2%, or at least about 5%, by weight of the coating. In an exemplary embodiment, the polysiloxane compound comprises about 10% by weight of the coating.

[0015] In an embodiment, the weight of the polysiloxane-based coating is greater than about 0.1% of the total weight of the fiber. In an embodiment, the weight of the coating is greater than about 5% of the total weight of the fiber, or from about 6% to about 10% of the total weight of the fiber. In other embodiments, the weight of the coating can be greater than 10% of the total weight of the fiber.

[0016] In embodiments, the polysiloxane-based coating comprises an active polysiloxane macroemulsion. For example, the polysiloxane emulsion may comprise a dimethylpolysiloxane emulsion, an amino-type polysiloxane emulsion, an organofunctional polysiloxane emulsion, a resinous polysiloxane emulsion, a film-forming polysiloxane emulsion, etc. In one embodiment, the active polysiloxane macroemulsion comprises amino-functional polydimethylsiloxane and / or tridecyl polyethylene glycol ether. In an exemplary embodiment, the amino-functional polydimethylsiloxane accounts for about 30% to about 40% of the coating weight. In embodiments, tridecyl polyethylene glycol ether accounts for about 5% to about 10% of the coating weight.

[0017] The fibers can be cut fibers or continuous fibers. Before applying the coating, the fibers can be bare (i.e., zero spin finish). Before applying the coating, the fibers can include a spin finish. In certain embodiments, the bare continuous fibers are spunbond fibers or meltblown fibers. In other embodiments, the cut fibers have less than about 2% conventional spin finish.

[0018] In some embodiments, the polysiloxane-based coating further comprises an antistatic agent. The antistatic agent may include a cationic antistatic agent, an anionic antistatic agent, a quaternary ammonium salt antistatic agent, or a surfactant. The surfactant may include a non-rewet heat degradable surfactant / foaming agent.

[0019] 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, PLA, cross-linked polyethylene, polycarbonate, polyacrylate, polyacrylonitrile, polyfumaronitrile, polystyrene, styrene maleic anhydride, polymethylpentene, cyclic olefin copolymers or fluorinated polymers, polytetrafluoroethylene, perfluoroethylene and hexafluoropropylene or copolymers with PVDF, such as P(VDF-TrFE), or terpolymers, such as P(VDF-TrFE). DF-TrFE-CFE), propylene, polyimide, polyetherketone, cellulose ester, nylon and polyamide, polymethacrylic acid, poly(methyl methacrylate), polyoxymethylene, polysulfone, acrylic acid, styrenated acrylic acid, pre-oxidized acrylic acid, fluorinated acrylic acid, vinyl acetate, vinyl acrylic acid, ethylene-vinyl acetate copolymer, styrene-butadiene, ethylene / vinyl chloride, vinyl acetate copolymer, latex, polyester copolymer, carboxyl styrene acrylic acid or vinyl acetate, epoxy resin, acrylic acid multipolymer, phenolic, polyurethane, cellulose, styrene or any combination thereof. Other conventional fiber materials are contemplated. In some embodiments, bicomponent chopped fibers are preferred, such as HDPE / PET, PP / PET, CoPET / PET. In some embodiments, oil-free bicomponent fibers can be produced via bicomponent spunbond technology and then a coating is applied.

[0020] The fiber can have a thickness suitable for the application. In some embodiments, at least one dimension of the fiber is in the range of about 1 micron to about 10,000 microns or about 1 micron to about 1,000 microns or about 10-100 microns. The thickness of the fiber can also be measured in denier, which is a unit for measuring the linear mass density of the fiber. In some embodiments, the linear density of the fiber can be about 1 denier to about 10 deniers. The fiber can be configured as a gradient density medium, wherein the pore size decreases from the upper surface (upstream) of the filter to the lower surface (downstream), and vice versa, to improve capture efficiency and dust holding capacity.

[0021] In some embodiments, the fiber layer may include a "high loft" nonwoven material comprising spunbond or through air bonded carded nonwoven fibers. As used herein, the term "high loft" refers to a volume of void space greater than the volume of total solids. In through air bonded carded nonwoven fibers, the loft of the fiber layer may be controlled by various methods known to those skilled in the art.

[0022] In certain embodiments, the fiber is a bicomponent fiber having a core and a sheath. In embodiments, the core is not concentric with the sheath. In other embodiments, the core is concentric with the sheath.

[0023] In certain embodiments, the filter media comprises a nonwoven material including a substrate, sheet, layer, film, apertured film, web, or other media comprising fibers coated with a polysiloxane-based coating.

[0024] In another aspect, an air filter, such as an HVAC filter or the like, is provided having one or more fibers coated with a polysiloxane-based coating comprising a polysiloxane compound diluted in water or other suitable fluid such that the polysiloxane compound comprises at least about 2% by weight of the coating, or at least about 5% by weight of the coating. In an exemplary embodiment, the polysiloxane compound comprises about 10% by weight of the coating.

[0025] Filter media comprising fibers coated with the silicon-based coatings described herein can be used to make supported, self-supporting, pleated or flat (non-pleated) air filters or HVAC filters with a minimum efficiency rating of at least MERV 6 according to ASHRAE 52.2. In some embodiments, the MERV rating is MERV 7, MERV 8, MERV 9, or even MERV 10.

[0026] In an embodiment, the E3 filtration efficiency of the filter medium is increased by about 30% or more compared to the E3 filtration efficiency value of the fiber without the polysiloxane-based coating, or by about 35% or more compared to the E3 filtration efficiency value of the fiber without the polysiloxane-based coating, or by about 40% or more compared to the E3 filtration efficiency value of the fiber without the polysiloxane-based coating.

[0027] In embodiments, the E2 filtration efficiency of the filter media is increased by about 20% or more compared to the E2 filtration efficiency value of the fiber without the polysiloxane-based coating.

[0028] In embodiments, the pressure drop of the filter is less than 10% of the pressure drop of the filter without the polysiloxane-based coating. In embodiments, the pressure drop is less than 5%, 1% or 0.5% of the pressure drop of the filter without the polysiloxane-based coating.

[0029] In embodiments, the air permeability of the filter is within 5% of the air permeability of the filter without the polysiloxane-based coating. In embodiments, the air permeability is less than 1% of the air permeability of the filter without the polysiloxane-based coating.

[0030] In certain embodiments, the MERV rating of the filter media can be improved simply by applying a polysiloxane-based coating. In certain embodiments of these embodiments, the filter media removes E3 particles with an efficiency of at least about 5 points, at least about 10 points, at least 18 points, or at least about 30 points. The MERV rating can be improved from MERV 7 to MERV 8, from MERV 8 to MERV 9, from MERV 7 to MERV 9, or even from MERV 7 to MERV 10.

[0031] The filter may also include a substantially rigid support layer connected to the filter medium. The fiber may include an extruded film including one or more holes for liquid flow. For example, the holes may be hexagonal, circular, square or diamond-shaped.

[0032] The filter may include pleats. For example, the fiber layer may include at least one fold forming a pleat in the fiber layer. In another example, the filter also includes a plurality of pleats extending on the surface of the fiber layer. The fiber layer may be pleatless.

[0033] In certain embodiments, the fibers in the filter media can be electrostatically charged, such that, for example, contaminants can be captured by mechanical and electrostatic filtration. For example, electrostatic or electret fibers can be high loft triboelectric filter media made by carding and needle punching.

[0034] In another aspect, a method of preparing a filter medium includes providing a plurality of fibers and applying a polysiloxane-based coating to the fibers. The coating includes at least about 2% or at least 5% of a silicon compound by weight of the coating. In an exemplary embodiment, the polysiloxane compound comprises about 10% by weight of the coating.

[0035] The coating is applied directly to the fibers, either after or before forming the fiber web.Applicants have discovered that applying the coating directly to the fibers improves the overall efficiency of the filter media, particularly the overall efficiency of capturing contaminants in the E2 or E3 particle populations.

[0036] In certain embodiments, the added weight of the polysiloxane-based coating is greater than about 1% based on the total weight of the fiber. In certain embodiments, the added weight is greater than about 5%, or from about 6% to about 10%, based on the total weight of the fiber.

[0037] In an embodiment, the polysiloxane-based coating comprises a reactive polysiloxane macroemulsion. The polysiloxane emulsion may include, for example, a dimethyl polysiloxane emulsion, an amino-type polysiloxane emulsion, an organofunctional polysiloxane emulsion, a resin-type polysiloxane emulsion, a film-forming polysiloxane emulsion, etc. In an exemplary embodiment, the reactive polysiloxane macroemulsion comprises amino-functional polydimethylsiloxane and / or polyethylene glycol monotridecyl ether.

[0038] The fibers can be made by any suitable process, including but not limited to meltblowing, spunbonding or hydroentanglement, bicomponent spunbonding, thermal bonding, carding, air-laid, wet-laid, extrusion, co-forming, needle-punching, stitching, hydraulic entanglement, etc. In certain embodiments, the bare continuous fibers are formed by a process selected from spunbonding and meltblowing. In other embodiments, the staple fibers incorporated into the filter media are formed by carding, air-laid, wet-laid, or similar processes.

[0039] In embodiments, the silicone-based coating may be applied by any suitable process, including but not limited to spraying the fibers with the silicone-based coating, dipping the fibers into a container containing the silicone-based coating, and applying the silicone-based coating to the fibers in the form of a foam.

[0040] The coating can be applied as a spin finish, or after a spin finish has been applied. The coating can be applied to bare fibers without a spin finish. The coating can be applied to chopped fibers to which a typical spin finish has been applied.

[0041] The recitation herein of desirable objectives met by various embodiments of this specification is not intended to imply or suggest that any or all of these objectives are present as essential features, either singly or collectively, in the most general embodiment of this specification or in any of its more specific embodiments. DETAILED DESCRIPTION OF THE INVENTION

[0043] This specification illustrates exemplary embodiments and should not be considered as limiting. The claims define 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 technologies are not shown or described in detail to avoid blurring the specification. The same numbers in two or more figures represent the same or similar elements. In addition, the elements and related aspects described in detail with reference to one embodiment may also be included in other embodiments that are not specifically shown or described, as long as practical. For example, if an element is described in detail with reference to one embodiment, but is not described with reference to a second embodiment, it can still be claimed that the element is included in the second embodiment. In addition, the description herein is for illustrative purposes only and does not necessarily reflect the actual shape, size or dimensions of the system or illustrated components.

[0044] It should be noted that the singular forms "a", "an", and "the", as well as any singular use of any term, used in this specification and the appended claims, include plural referents unless expressly and unambiguously limited to one referent. The term "include" and its grammatical variations as used herein are intended to be non-limiting, such that the listing of items in a list does not exclude other similar items that can be substituted or added to the listed items.

[0045] Unless otherwise indicated, any quantitative values ​​are approximate, whether or not the words "about" or "approximately" are recited. The materials, methods, and examples described herein are illustrative only and not intended to be limiting.

[0046] Provided are filter media and filters including fibers having a polysiloxane-based coating, such as gas or liquid filters, face masks, CPAP filters, vacuum bags, cabin air filters, HVAC furnace filters, home air filters, commercial air filters, gas turbine and compressor air intake filters, panel filters, etc. Also provided are systems and methods for making such filters.

[0047] The polysiloxane-based coating includes a polysiloxane compound diluted in water or other suitable fluids such that the polysiloxane compound accounts for at least about 2% or at least about 5% by weight of the coating. In an exemplary embodiment, the polysiloxane compound accounts for about 10% by weight of the coating. In an exemplary embodiment, the polysiloxane compound comprises a polysiloxane material, a surfactant, and water. The polysiloxane and the surfactant together account for about 10% by weight of the entire coating.

[0048] Applicants have discovered that coating fibers directly with the polysiloxane-based coatings described herein (as opposed to applying the coatings to the exterior surface of already formed filter media) greatly improves the efficiency of such filters in capturing pollutants, particularly pollutants in the E2 and E3 particle group ranges. Furthermore, such coatings do not substantially compromise other important filter properties, such as filter cost, life, dust holding capacity, and pressure drop or air permeability.

[0049] The weight of the polysiloxane-based coating may be greater than about 0.1% of the total weight of the fiber. In an exemplary embodiment, the weight of the coating is greater than about 5% of the total weight of the fiber or is from about 6% to about 10% of the total weight of the fiber.

[0050] In embodiments, the coating based on polysiloxane comprises a macro-emulsion of active polysiloxane. Polysiloxane emulsions are insoluble polysiloxanes that are substantially uniformly dispersed in water with the help of surfactants. For example, polysiloxane emulsions can include dimethylpolysiloxane emulsions, amino-type polysiloxane emulsions, organofunctional polysiloxane emulsions, resin-type polysiloxane emulsions, film-forming polysiloxane emulsions, etc. In exemplary embodiments, the macro-emulsion of active polysiloxane comprises amino-functional polydimethylsiloxane and / or tridecyl polyethylene glycol ether. In embodiments, amino-functional polydimethylsiloxane accounts for about 30% to about 40% of the coating weight. In embodiments, tridecyl polyethylene glycol ether accounts for about 5% to about 10% of the coating weight.

[0051] The fibers can be cut fibers or continuous fibers. The fibers can be bare (i.e., zero spinning finish) before the coating is applied. The fibers can include spinning finishes before the coating is applied. Spinning finishes can include, but are not limited to, lubricants, emulsifiers, antistatic agents, antimicrobial agents, adhesives, and wetting agents. Other organic liquids, such as alcohols or organic liquid mixtures, can be added to the spinning finish. Spinning finishes can be applied during the carding of the fibers, during the melt spinning operation, or during the fiber drawing, curling, and cutting operations.

[0052] In an embodiment, the polysiloxane-based coating further comprises an antistatic agent. The antistatic agent may include a surfactant. The surfactant may include a non-remoisture thermally degradable surfactant / foaming agent.

[0053] In certain embodiments, the filter media comprises a nonwoven material, which includes a fiber-containing substrate, sheet, layer, film, apertured film, web, or other media.

[0054] The nonwoven fiber layer discussed herein can include single fibers or line structures that are intermingled, interlocked or bonded together. Nonwoven fabrics can include sheets or web structures that are bonded together by mechanically, thermally or chemically winding fibers or filaments (and by perforating the film). They can be substantially flat porous sheets directly made of independent fibers or molten plastics or plastic films. The example of suitable nonwoven material includes but is not limited to fibers, layers or webs of meltblowing, spunbond or spunlace, thermal bonding, bonding combing, air-laid, wet-laid, co-molding, acupuncture, stitching, hydraulic winding, etc.

[0055] In certain embodiments, the fiber layer can include knitted and / or woven materials. Knitted materials can include any knitting pattern suitable for the desired application. Knitted materials suitable for filter applications include weft knitting, warp knitting, knitted meshes, compressed knitted meshes, etc. Woven materials suitable for filter applications include textile filter media, such as monofilament fabrics, multifilament fabrics, nylon nets, polyester nets, polypropylene nets, etc. For example, woven textiles can be used for screen filter press filter cloths, woven filter pads and other die-cut pieces, centrifuge filter bags, liquid filter bags, dust collector filter bags, bed dryer filter bags, rotary drum filters, filter belts, leaf filters, roll media, etc.

[0056] In some embodiments, nonwoven materials can include structures containing short-cut fibers and / or filaments, which are interlaced or entangled with each other. Short-cut fibers used herein refer to fibers of limited length. Filaments used herein refer to fibers of substantially continuous length. In some embodiments, fibers can include short-cut coarse fibers, microfibers and / or fine fibers. "Fine fibers" used herein refer to fibers with a diameter less than 1 micron, "coarse fibers" refer to fibers with a diameter greater than 10 microns, and microfibers refer to synthetic fibers with a diameter less than 10 microns.

[0057] The fibers contemplated may be made by any process including, but not limited to, air-laid or dry-laid, carding, spinneret, gel spinning, melt spinning, wet spinning, dry spinning, islands-in-a seastaple or spunbond, segmented pie staple or spunbond, and the like. Such methods are described in U.S. Pat. Nos. 4,406,950, 6,338,814, 6,616,435, 6,861,142, 7,252,493, 7,300,272, 7,309,430, 7,422,071, 7,431,869, 7,504,348, 7,774,077 9,522,357, 9,993,761 and U.S. Patent Publication No. 2009 / 266,759, the entire disclosures of which are hereby incorporated herein by reference for all purposes.

[0058] The cross-section of the contemplated fibers can have a variety of shapes, including but not limited to round, kidney bean, dog bone, trilobal, barbell, bow tie, star, Y, etc. These shapes and / or other conventional shapes can be used in embodiments to obtain the desired performance characteristics. The fibers are interconnected by thermal and chemical bonds, intertwining, using a binder (such as an adhesive), etc.

[0059] 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, PLA, high density polyethylene ("HDPE"), LLDPE, cross-linked polyethylene, polycarbonate, polyacrylate, polyacrylonitrile, polyfumaronitrile, polystyrene, styrene maleic anhydride, polymethylpentene, cyclic olefin copolymers or fluorinated polymers, polytetrafluoroethylene, perfluoroethylene and hexafluoropropylene or copolymers with PVDF, such as P(VDF-TrFE), or terpolymers, such as P(VDF-TrFE). DF-TrFE-CFE), propylene, polyimide, polyetherketone, cellulose ester, nylon and polyamide, polymethacrylic acid, poly(methyl methacrylate), polyoxymethylene, polysulfone, acrylic acid, styrenated acrylic acid, preoxidized acrylic acid, fluorinated acrylic acid, vinyl acetate, vinyl acrylic acid, ethylene-vinyl acetate copolymer, styrene-butadiene, ethylene / vinyl chloride, vinyl acetate copolymer, latex, polyester copolymer, carboxyl styrene acrylic acid or vinyl acetate, epoxy resin, acrylic acid multipolymer, phenolic resin, polyurethane, cellulose, styrene or any combination thereof. Other conventional fiber materials are contemplated. In some embodiments, the coating is applied to the bicomponent fiber. Such bicomponent fibers can be produced via melt spinning, spunbonding or melt blowing.

[0060] The fibers may include fibers of varying sizes, with the diameters typically ranging from about 1 micron to about 1000 microns and lengths ranging from about half an inch to three inches. The fibers may be configured as a gradient density media, where the pore size decreases from the upper surface (upstream) to the lower surface (downstream) of the filter to increase capture efficiency and dust holding capacity. Alternatively, this configuration may be reversed.

[0061] The fibers in the media may be held connected to other fibers by thermal bonding, chemical bonding, or intertwining. Bicomponent fibers may be used, particularly in mechanical filtration, where the bicomponent fibers are formed by extruding two polymers from the same spinneret, the two polymers being contained in the same filament. Suitable materials for bicomponent fibers include, but are not limited to, polypropylene (PP) / polyethylene (PE), polyethylene terephthalate (PET) / polypropylene (PP), HDPE / PET, PP / PET, CoPET / PET, and the like.

[0062] In some embodiments, the fiber layer may include a "high loft" nonwoven material comprising a spunbond or hot air bonded carded nonwoven fiber. As used herein, the term "high loft" refers to a volume of void space greater than the volume of total solids. In the hot air bonded carded nonwoven fiber, the loft of the fiber layer can be controlled in various ways known to those skilled in the art. For example, during bonding, the loft can be increased by applying a smaller compressive force to the medium. In another example, a fiber with a larger thickness (e.g., a thickness greater than 3 deniers, such as 5 deniers or greater, 6 deniers or greater) can be used to make a high loft nonwoven material (discussed in detail below). In other embodiments, the loft can be increased by using non-concentric bicomponent fibers.

[0063] The fiber can have a thickness suitable for the application. In some embodiments, at least one dimension of the fiber is in the range of about 1 micron to about 10,000 microns, or about 1 micron to about 1,000 microns, or about 10-100 microns. The thickness of the fiber can also be measured in denier, which is a unit of measure for the linear mass density of the fiber. In some embodiments, the linear density of the fiber can be about 1 denier to about 10 deniers.

[0064] In some embodiments, the filter media can include at least two different fiber thicknesses or linear densities to provide at least two different filter layers in the same filter media. In some embodiments, the filter media can include three or more different sections or layers with different fiber denier ranges in each section.

[0065] In some embodiments, the fiber layer may include additives, such as antibacterial and / or antiviral ingredients, such as silver, zinc, copper, silicone, tributyltin, organic compounds containing chlorine, bromine or fluorine compounds, and the like.

[0066] The fibers may include bicomponent fibers, which include two or more different fibers bonded to one another. The fibers may comprise the same material or different materials.

[0067] In certain embodiments, the fibers can be electrostatically charged so that, for example, contaminants are captured by mechanical and electrostatic filtration. The fibers can be electrostatically charged using triboelectric methods, corona discharge, electrostatic fiber spinning, hydrocharging, charging rods, or other known methods. Corona charging is suitable for charging single polymer fibers, fiber blends, or fabrics. Tribocharging can be suitable for charging fibers with different electronegativity. Electrostatic or electret fibers can include high-loft triboelectric filtration media made by combing and needle punching. Electrostatic fiber spinning combines polymer charging and fiber spinning into a one-step process. U.S. Patent No. 9,074,301 describes a method suitable for triboelectric charging, and the entire disclosure of the patent is hereby incorporated herein by reference for all purposes.

[0068] In certain embodiments, the nonwoven materials discussed herein can be included as part of a filtration device that captures or absorbs contaminants, such as as a liquid filter, a gas filter for home and commercial air filtration (e.g., HVAC), a surgical mask or other face mask, etc. The filtration device can be a mechanical filter, an absorption filter, a sequestration filter, an ion exchange filter, a reverse osmosis filter, a surface filter, a depth filter, etc., and can be designed to remove a variety of different types of contaminants from air, water, or other.

[0069] In some embodiments, the filter media can be scored, pleated or folded into a pleated filter. The pleats can be formed by various conventional pleating operations, including but not limited to bar, rotary and star gear pleating operations. The filter includes one or more support layers bonded to the filter media. In some embodiments, a polymer layer, membrane or film is provided that includes one or more holes for gas or liquid flow. In other embodiments, the material includes a flexible surface layer for a finger bandage pad, a face mask or the like.

[0070] In one such embodiment, the nonwoven material is incorporated into an air filter that removes particles and pollutants from the air, such as a HEPA filter (i.e., a pleated mechanical air filter), a UV light filter, an electrostatic filter, a washable filter, a media filter, a glass fiber filter, a pleated or non-pleated air filter, an activated carbon filter, a bag filter, a V-bank compact filter, a filter sheet, a flat cell filter, a filter element, etc. The fibers may comprise a filter media for an air filter and may be supported by a support layer or a scrim layer, or may be included in other layers or materials.

[0071] Traditional home and commercial air filters, such as HEPA or pleated filters, are typically rated based on the filter's ability to capture particles of approximately 0.3-10 microns. This rating is called the Minimum Efficiency Reporting Value, or MERV, and is established by the American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE). MERV ratings range from 1-16, with higher values ​​indicating greater efficiency in capturing a particular type of particle. During testing, it is also common to compare efficiency values ​​based on the size of particles in the airstream. The E3, E2, and E1 values ​​refer to particle efficiencies of 3-10 microns, 1-3 microns, and 0.3-1 microns, respectively.

[0072] The MERV ratings of the filter media discussed herein will vary depending on many factors, including the type and size of fibers used in the filter media, the width of the filter media, the number and size of pleats (if any), etc. Likewise, the pressure drop across the filter media will also depend on many factors, including those listed above.

[0073] In certain embodiments, filter media comprising fibers coated with the silicon-based coatings described herein can be used to make supported, self-supporting, or flat-sheet (non-pleated) air filters or HVAC filters having a minimum efficiency rating (MERV) of at least MERV 6 according to ASHRAE 52.2. In some embodiments, the MERV rating is MERV 7, MERV 8, MERV 9, or even MERV 10.

[0074] In certain embodiments, the polysiloxane-based coating improves the efficiency of the filter medium in capturing pollutants in the E2 and / or E3 particle groups compared to a filter medium without a polysiloxane-based coating. In these embodiments, the MERV rating of the filter medium can be improved only by applying a polysiloxane-based coating. In certain embodiments of these embodiments, the filter medium removes the efficiency of E3 particles by at least about 5 points, at least about 10 points, at least about 18 points, or at least about 30 points. The MERV rating can be increased from MERV 7 to MERV 8, or from MERV 8 to MERV 9, or from MERV 7 to MERV 9 or even MERV 10.

[0075] In certain embodiments, the fiber layer is a filter media for a gas filter (e.g., an HVAC filter). In embodiments, the filter media has an E3 filtration efficiency that is increased by about 30% or more compared to the E3 filtration efficiency value of the fiber without the polysiloxane-based coating, or an E3 filtration efficiency that is increased by about 35% or more compared to the E3 filtration efficiency value of the fiber without the polysiloxane-based coating, or an E3 filtration efficiency that is increased by about 40% or more compared to the E3 filtration efficiency value of the fiber without the polysiloxane-based coating.

[0076] In embodiments, the E2 filtration efficiency of the filter media is increased by about 20% or more compared to the E2 filtration efficiency value of the fiber without the polysiloxane-based coating.

[0077] In embodiments, the tested pressure drop of the filter is less than 10% of the pressure drop of the filter without the polysiloxane-based coating. In embodiments, the pressure drop is less than 5%, 1% or 0.5% of the pressure drop of the filter without the polysiloxane-based coating.

[0078] In embodiments, the air permeability of the filter is within 5% of the air permeability of the filter without the polysiloxane-based coating. In embodiments, the air permeability is less than 1% of the air permeability of the filter without the polysiloxane-based coating.

[0079] Other types of filters that can be developed using the nonwoven materials disclosed herein include conical filter elements, square end cap filter elements, bag filters, V-bank compact filters, plate filters, flat cell filters, pleated or non-pleated bag filter element filters, and the like.

[0080] In certain embodiments, the nonwoven material may be included in a film or layer that includes holes, pores, or perforations. The holes may be embossed into a pattern (e.g., circles, diamonds, hexagons, rectangles, triangles, rectangles, etc.) and then stretched until holes are formed in the thinned areas produced by the embossing. Such porous substrates may be formed from a variety of polymers, such as polypropylene, polyethylene, high-density polyethylene ("HDPE"), etc. For example, the polymer layer may include an extruded film. Porous films are commercially available as The substrate is supplied in rolls and the nanofibers are deposited into the substrate by a roll-to-roll process.

[0081] The fibers may be made by any suitable process including, but not limited to, meltblowing, spunbonding or hydroentanglement, thermal bonding, carding, air-laid, wet-laid, extrusion, coform, needlepunching, stitching, hydroentanglement, and the like.

[0082] In certain embodiments, the exposed continuous fibers are formed by a process selected from spunbond and meltblown. In an example, the system may include a spunbond line, wherein filaments are formed by spunmelt polymer and stretched molten filaments. The filament fiber bundles are separated and spread, and then layered on the net to form a web. The fibers are bonded in the form of sheets by thermal bonding and embossing. For example, a fiber stream may be introduced before the attenuation zone or before the bonding (reinforcement) process.

[0083] In another embodiment, the fibers can be formed using a meltblowing die. Examples of suitable meltblowing dies that can be used to make nonwoven materials are discussed in detail in U.S. Patent Nos. 6,972,104, 8017534, and 7772456, and U.S. Patent Application No. US20200216979A1, the entire disclosures of which are incorporated herein by reference in their entirety for all purposes.

[0084] In other embodiments, the cut fibers are formed by combing, air-laid, wet-laid or similar processes. In one embodiment, the system may include a carding machine or two carding machines placed in series with each other. The short fiber lengths are processed into a continuous fiber web by fiber opening, fiber blending and fiber reinforcement. Once the fiber web is formed by combing, a secondary bonding process can be used to give the fiber web integrity and strength. This bonding process can be accomplished by chemical, thermal or mechanical methods.

[0085] Preferably, the coating is applied directly to the fibers prior to forming the fiber web. Applicants have found that applying the coating directly to the fibers (as opposed to applying it to an already formed filter media surface) improves the overall efficiency of the filter media, particularly the overall efficiency of capturing contaminants in the E2 or E3 particle populations.

[0086] In embodiments, the silicone-based coating is applied by any suitable process, including but not limited to spraying the fibers with the silicone-based coating, dipping the fibers into a container containing the silicone-based coating, and applying the silicone-based coating to the fibers in the form of a foam.

[0087] The coating can be applied as a spin finish, or after a spin finish has been applied. The coating can be applied to bare fibers without a spin finish. Example

[0088] Applicants conducted four different experiments with various fibers in filter media. The fibers were tested before and after a polysiloxane-based coating was applied to the fibers. The testing measured the pressure drop across each filter media and the initial fractional efficiency of the filter media for three different particle populations: (1) E1 particles with a size of about 0.3 microns to 1 micron; (2) E2 particles with a size of about 1 micron to 3 microns; and (3) E3 particles with a size of about 3 microns to about 10 microns. The testing was conducted at a filtration velocity of 180 feet per minute. All MERV ratings reported here (based on the flat plate fractional efficiency test) are predicted MERV ratings.

[0089] The coating includes a polysiloxane compound of an active polysiloxane macroemulsion, a non-wetting thermally degradable surfactant / foaming agent and water. The fiber is pad-finished (although no oil is applied in some cases), the coating is then applied to the fiber and dried at 240 degrees Fahrenheit for 3 minutes. In the first test, the coating contained only 10 grams of polysiloxane compound, 1 gram of surfactant and 989 grams of water. Therefore, by weight, the coating contains about 1% polysiloxane compound. In the second, third and fourth tests, the percentage of polysiloxane compound and surfactant was increased to 100 grams of polysiloxane compound and 10 grams of surfactant for 890 grams of water (i.e., about 10% polysiloxane compound by weight).

[0090] Tables 1 and 2 below show the results of the first test. The test was conducted on 3 different samples and the average values ​​are reported. Note that G6 spin finish is a regular spin finish from Fibervisions, Inc., while G8 is a specific finish for filtration applications. Both spin finishes were applied during the fiber production process. Fibers coated with G8 spin finish had higher efficiency than fibers coated with G6 spin finish. Cut fibers are defined as non-continuous fibers with a relatively short length. The filter media was tested before and after coating. The filter media was made of bicomponent fibers and G6 spin finish. The fibers were carded and then thermally bonded. The coating formulation included 1% polysilicone compound, 0.1% surfactant, and 98.9% water. As shown in Table 2, the efficiency of the filter media increased with the addition of coating for all three particle groups, with the largest increase in efficiency for the E3 particle group, which increased by more than 12% (from 55.5 to 62.4). However, this increase was not enough to change the MERV rating of the filter media. The change in pressure drop was negligible.

[0091] Table 1

[0092]

[0093] Table 2

[0094]

[0095] Tables 3-5 show the results of the second test. This test was conducted with 5 different samples of cut fibers with G6 oil in a MERV 7 filter media. The results in Tables 3-5 are the averages of all 5 samples. The coating was increased to 10% polysilicone compound and 1% surfactant and 89% water. As shown, for all three particle groups, the efficiency of the filter media increased with the increase in coating, with the greatest increase in efficiency for the E3 particle group, which increased by 18.8 points, or more than 35%. This increased the overall MERV rating of the filter from MERV 7 to MERV 8. The increase in pressure drop was negligible. The air permeability was reduced by only 0.9%. The basis weight change caused by the coating was 8.3%. Therefore, the coating significantly improved the filtration efficiency of the filter media in the E3 zone, but did not significantly increase the pressure drop or air permeability. In addition, the dust holding capacity of the filter media only decreased from 8.37 grams of dust per square foot (gsf) to 8.15 gsf (see Table 5).

[0096] Table 3

[0097]

[0098] Table 4

[0099]

[0100] Table 5

[0101] sample <![CDATA[Dust holding capacity (grams of dust / ft 2 )]]> Before treatment 8.37 After treatment 8.15

[0102] Comparison of the results of the first and second tests shows that increasing the weight percentage of the polysiloxane compound in the coating significantly increases the efficiency of the filter media.

[0103] Tables 6 and 7 show the results of the third test. This test tested two different filter media. The first filter media included 5 non-continuous fiber or cut fiber samples, half of which had been coated with G8 spin finish (labeled Staple). The results in Tables 6 and 7 show the average of all 5 samples. As shown, the coating did not improve the efficiency of the filter media for particle groups E1 or E2, while for particle group E3, it slightly increased the efficiency by 6.2%, thereby improving the overall MERV rating of the filter from MERV 8 to MERV 9.

[0104] The second filter media included 5 continuous fiber samples (labeled CON) manufactured by spunbond technology. These fibers were bare, i.e., they did not include a filter coating or spin finish. The results in Tables 6 and 7 show the average of all 5 samples. As shown, with the addition of coating, the filter media's efficiency for the E2 particle population increased by 23% and the efficiency for the E3 particle population increased by 23.8 points, or more than 38%. This increased the overall MERV rating of the filter from MERV 7 to MERV 10. The increase in pressure drop was only 8.2%. The air permeability was reduced by only 1.6%. The basis weight change caused by the coating was 6.8%. Therefore, the coating significantly improved the filtration efficiency of the filter media for the E2 and E3 particle populations, but had minimal impact on pressure drop or air permeability.

[0105] Table 6

[0106]

[0107] Table 7

[0108]

[0109] The third test showed that the silicone-based coating was more effective on bare fibers that were not coated prior to application of the silicone-based coating.

[0110] Tables 8-11 show the results of the fourth test. This test tested two samples of each of the various bicomponent spunbond continuous fiber samples (each fiber is labeled with a name, such as 5-2, 4B3, etc.). The results show the average of the two samples of each fiber. Table 8 shows the sample weight, basis weight, thickness and air permeability of each fiber before applying the polysiloxane-based coating. All samples were about 12 inches in width and length and 144 inches in area. 2 .

[0111] Table 8

[0112]

[0113] Tables 9-11 show the filtration efficiency and pressure drop results for each fiber before and after coating with the polysiloxane-based compound. As shown, the coatings provided a modest improvement in filtering E2 particles and a significant improvement in filtering E3 particles. The average improvement in filtration efficiency for all samples (Table 11) was 6.4% for E2 particles and 41.9% (or 22.8 points) for E3 particles. The smallest change in efficiency for E3 particles across all samples was still an improvement of 32.83%.

[0114] The average pressure drop caused by the polysiloxane-based compound was only 4.9%, with the highest pressure drop being 12.9%. Thus, the coating significantly increased the filtration efficiency of the filter media in the E3 particle population without significantly increasing the pressure drop across the filter.

[0115] Table 9: Before treatment

[0116]

[0117] Table 10: After treatment

[0118]

[0119]

[0120] In an optional embodiment, the filter can also include nanoparticles incorporated into the fiber layer or filter medium. As used herein, the term "nanoparticle" refers to any particle having a size less than 1 micron on at least one axis or dimension. For example, fibers having a diameter or width less than 1 micron and a length greater than 1 micron are nanoparticles used herein. The length of the nanofiber can be continuous, or the length of the nanofiber can be discrete, for example 1-100,000 microns, preferably about 100-10,000 microns.

[0121] In certain embodiments, the nanoparticles are dispersed in the fiber layer "to a certain depth". As used herein, the term "to a certain depth" refers to that the nanoparticles are dispersed beyond the first surface of the fiber layer so that at least some of the nanoparticles are dispersed between the first surface and the second opposing surface in the internal structure of the fiber layer or fiber medium. In certain embodiments, the nanoparticles are substantially dispersed in the entire medium from the first surface to the relative second surface. In other embodiments, the nanoparticles are dispersed in a portion of the medium from the first surface to a position between the first surface and the second surface.

[0122] Nanoparticles can be selected to have different triboelectric properties relative to the first or second fibers in order to utilize the triboelectric effect to enhance particle removal. In this way, the generated nanoparticles are formed in an electric field and are not easily contaminated by chemicals that may mitigate the triboelectric effect. Nanoparticles having different adsorption properties 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 a local electric field gradient in the filter media to enhance particle removal. The nanoparticles and the coarse fibers can have different wetting properties.

[0123] The nanoparticles can comprise any suitable material, such as glass, biosoluble glass, ceramic materials, acrylic, carbon, metals (e.g., alumina), polymers (e.g., nylon, polyethylene terephthalate, etc.), polyvinyl chloride (PVC), polyolefins, polyacetals, polyesters, cellulose ethers, polyalkylene sulfides, poly(arylene oxides), polysulfones, modified polysulfone polymers and polyvinyl alcohol, polyamides, polystyrene, polyacrylonitrile, polyvinylidene chloride, polymethyl methacrylate, polyvinylidene fluoride, and any combination thereof.

[0124] In some embodiments, nanoparticles are attached to fibers via mechanical winding. This mechanical bonding can be supplemented with adhesives or tackiness agents. In certain embodiments, nanoparticles are not curled (i.e., they do not include the obvious wavy shape, curved shape, curled shape, coiled sawtooth shape or similar shape associated with relaxed state nanoparticles). In other embodiments, nanoparticles can have a curled body structure with discrete lengths. For example, when these curled nanofibers with discrete lengths are attached to fibers, they can be entangled with each other, and are entangled with the fibers by firmly attaching, entangled on the fibers and around the fibers, forming modified fibers. In other embodiments, the attachment of nanofibers to microfibers is realized via static charge attraction and / or van der Waals attraction between fibers and nanoparticles. A more complete description of the filter medium incorporating nanoparticles can be found in co-assigned, co-pending international patent application serial number PCT / US2023 / 17967 filed on April 7, 2023, for all purposes, the entire disclosure of which is incorporated herein by reference as a whole.

[0125] Although the apparatus, system and method have been described in detail according to certain preferred embodiments, many modifications and changes may be made thereto by those skilled in the art. Therefore, the above description should not be interpreted as being limited thereto, but should be interpreted as including the above obvious changes and being limited only by the spirit and scope of the following claims.

[0126] For example, in a first aspect, a first embodiment is a filter medium comprising a layer comprising one or more fibers. The fibers are coated with a polysiloxane-based coating comprising at least about 2% polysiloxane compound by weight of the coating.

[0127] A second embodiment is the first embodiment wherein the polysiloxane compound is at least about 5% by weight of the coating.

[0128] A third embodiment is any combination of the first two embodiments, wherein the polysilicone compound is at least about 10% by weight of the coating.

[0129] A fourth embodiment is any combination of the first three embodiments, wherein the add-on weight of the polysiloxane-based coating is greater than about 1%, based on the total weight of the fiber.

[0130] A fifth embodiment is any combination of the first four embodiments, wherein the add-on weight is greater than about 5% based on the total weight of the fiber.

[0131] A sixth embodiment is any combination of the first five embodiments, wherein the add-on weight is from about 6% to about 10% based on the total weight of the fiber.

[0132] The seventh embodiment is any combination of the first six embodiments, wherein the fibers are staple fibers.

[0133] An eighth embodiment is any combination of the previous seven embodiments, wherein the fibers are continuous fibers.

[0134] The ninth embodiment is any combination of the first eight embodiments, wherein the continuous fibers are release fibers or meltblown fibers.

[0135] The tenth embodiment is any combination of the previous nine embodiments, wherein the silicone-based coating comprises a reactive silicone macroemulsion.

[0136] An eleventh embodiment is any combination of the previous ten embodiments, wherein the polysiloxane-based coating comprises an amino-functional polydimethylsiloxane.

[0137] A twelfth embodiment is any combination of the previous eleven embodiments, wherein the silicone-based coating comprises polyethylene glycol monotridecyl ether.

[0138] A thirteenth embodiment is any combination of the previous twelve embodiments, wherein the amino-functional polydimethylsiloxane comprises from about 30% to about 40% by weight of the coating.

[0139] A fourteenth embodiment is any combination of the previous thirteen embodiments, wherein the polyethylene glycol monotridecyl ether comprises from about 5% to about 10% by weight of the coating.

[0140] The fifteenth embodiment is any combination of the previous fourteen embodiments, wherein the polysiloxane-based coating further comprises an antistatic agent.

[0141] The sixteenth embodiment is any combination of the preceding fifteen embodiments, wherein the antistatic agent comprises a surfactant.

[0142] The seventeenth embodiment is any combination of the previous sixteen embodiments, wherein the surfactant comprises a non-remoisturizing thermally degradable surfactant / foaming agent.

[0143] An eighteenth embodiment is any combination of the previous seventeen embodiments, wherein the silicone-based coating is applied to the fiber by dipping the fiber into a container containing the silicone-based coating.

[0144] In a second aspect, a gas filter product comprises a filter medium of any combination of the preceding eighteen embodiments.

[0145] In a third aspect, an air filter product for a heating, ventilation, and air conditioning (HVAC) system comprises the filter media of any combination of the preceding eighteen embodiments.

[0146] In a fourth aspect, a filter media includes a layer comprising continuous fibers having less than about 1% spin finish and a silicone-based coating on the fibers, wherein the silicone-based coating has an add-on weight greater than about 1% based on the total weight of the fibers.

[0147] A second embodiment is the first embodiment, wherein the spin finish is about 0%.

[0148] A third embodiment is any combination of the first two embodiments, wherein the add-on weight is at least about 5%, based on the total weight of the fiber.

[0149] A fourth embodiment is any combination of the first three embodiments, wherein the add-on weight is at least about 8% to about 10% based on the total weight of the fiber.

[0150] A fifth embodiment is any combination of the first four embodiments, wherein the filter media has an E3 filtration efficiency increased by at least about 30% compared to the E3 filtration efficiency value of the fiber without the polysiloxane-based coating.

[0151] A sixth embodiment is any combination of the first five embodiments, wherein the E3 filtration efficiency of the filter media is increased by about 35% or more compared to the E3 filtration efficiency value of the fiber without the polysiloxane-based coating.

[0152] A seventh embodiment is any combination of the first six embodiments, wherein the filter media has an E3 filtration efficiency increased by about 40% or more compared to the E3 filtration efficiency value of the fiber without the polysiloxane-based coating.

[0153] An eighth embodiment is any combination of the first seven embodiments, wherein the E2 filtration efficiency of the filter media is increased by about 20% or more compared to the E2 filtration efficiency value of the fiber without the polysiloxane-based coating.

[0154] A ninth embodiment is any combination of the first eight embodiments, wherein the silicone-based coating comprises at least about 2% silicone compound by weight of the coating.

[0155] The tenth embodiment is any combination of the previous nine embodiments, wherein the silicone-based coating comprises at least about 5% silicone compound by weight of the coating.

[0156] An eleventh embodiment is any combination of the previous ten embodiments, wherein the polysilicone compound is at least about 10% by weight of the coating.

[0157] A twelfth embodiment is any combination of the previous eleven embodiments, wherein the silicone-based coating comprises a reactive silicone macroemulsion.

[0158] The thirteenth embodiment is any combination of the previous twelve embodiments, wherein the polysiloxane-based coating comprises an amino-functional polydimethylsiloxane.

[0159] The fourteenth embodiment is any combination of the previous thirteen embodiments, wherein the silicone-based coating comprises polyethylene glycol monotridecyl ether.

[0160] A fifteenth embodiment is any combination of the fourteen previous embodiments, wherein the amino-functional polydimethylsiloxane comprises from about 30% to about 40% by weight of the coating.

[0161] A sixteenth embodiment is any combination of the fifteen preceding embodiments, wherein the polyethylene glycol monotridecyl ether comprises from about 5% to about 10% by weight of the coating.

[0162] The seventeenth embodiment is any combination of the previous sixteen embodiments, wherein the continuous fibers are spunbond fibers or meltblown fibers.

[0163] The eighteenth embodiment is any combination of the previous seventeen embodiments, wherein the polysiloxane-based coating further comprises an antistatic agent.

[0164] The nineteenth embodiment is any combination of the previous eighteen embodiments, wherein the antistatic agent comprises a surfactant.

[0165] The twentieth embodiment is any combination of the previous nineteen embodiments, wherein the surfactant comprises a non-remoisturizing thermally degradable surfactant / foaming agent.

[0166] The twenty-first embodiment is any combination of the previous twenty embodiments, wherein the silicone-based coating is applied to the fiber by dipping the fiber into a container containing the silicone-based coating.

[0167] In a fifth aspect, an air filter product comprises filter media of any combination of the first twenty-one embodiments.

[0168] In a sixth aspect, a first embodiment is a method of making a filter media comprising providing a plurality of fibers and applying a polysiloxane-based coating to the fibers, wherein the polysiloxane-based coating comprises at least about 2% polysiloxane compound by weight of the coating.

[0169] A second embodiment is the first embodiment wherein the polysiloxane compound is at least about 5% by weight of the coating.

[0170] A third embodiment is any combination of the first two embodiments, wherein the polysiloxane compound is at least about 10% by weight of the coating.

[0171] A fourth embodiment is any combination of the first three embodiments, wherein the add-on weight of the polysiloxane-based coating is greater than about 1%, based on the total weight of the fiber.

[0172] A fifth embodiment is any combination of the first four embodiments, wherein the add-on weight is greater than about 5% based on the total weight of the fiber.

[0173] A sixth embodiment is any combination of the first five embodiments, wherein the add-on weight is from about 6% to about 10% based on the total weight of the fiber.

[0174] The seventh embodiment is any combination of the first six embodiments, wherein the polysiloxane-based coating is applied by a process selected from the group consisting of spraying the fiber with the polysiloxane-based coating, dipping the fiber into a container containing the polysiloxane-based coating, and applying the polysiloxane-based coating to the fiber in the form of a foam.

[0175] The eighth embodiment is any combination of the first seven embodiments, further comprising forming the fibers by a process selected from spunbonding and meltblowing.

[0176] The ninth embodiment is any combination of the first eight embodiments, wherein a silicone-based coating is applied as a spin finish.

[0177] The tenth embodiment is any combination of the previous nine embodiments, wherein the silicone-based coating is applied to the fibers prior to forming the filter media.

[0178] In a seventh aspect, an air filter is made by the method of any combination of the first ten embodiments.

Claims

1. Filter media, including: a layer containing one or more fibers; and wherein the fibers are coated with a polysiloxane-based coating, the polysiloxane-based coating comprising at least about 2% of a polysiloxane compound, based on the weight of the coating.

2. The filter medium of claim 1, wherein the polysiloxane compound is at least about 5% by weight of the coating.

3. The filter medium of claim 1, wherein the polysiloxane compound is at least about 10% by weight of the coating.

4. The filter media of claim 1, wherein the add-on weight of the polysiloxane-based coating is greater than about 1% based on the total weight of the fibers.

5. The filter media of claim 4, wherein the added weight is greater than about 5% based on the total weight of the fibers.

6. The filter media of claim 4, wherein the add-on weight is from about 6% to about 10% based on the total weight of the fibers.

7. The filter media of claim 1, wherein the fibers are staple fibers.

8. The filter media of claim 1, wherein the fibers are continuous fibers.

9. The filter medium of claim 8, wherein the continuous fibers are spunbond fibers or meltblown fibers.

10. The filter media of claim 1, wherein the silicone-based coating comprises a reactive silicone macroemulsion.

11. The filter media of claim 1 , wherein the polysiloxane-based coating comprises an amino-functional polydimethylsiloxane.

12. The filter media of claim 1, wherein the silicone-based coating comprises polyethylene glycol monotridecyl ether.

13. The filter media of claim 11, wherein the amino-functional polydimethylsiloxane comprises from about 30% to about 40% by weight of the coating.

14. The filter medium of claim 12, wherein the polyethylene glycol monotridecyl ether comprises from about 5% to about 10% by weight of the coating.

15. The filter media of claim 1, wherein the polysiloxane-based coating further comprises an antistatic agent.

16. The filter medium of claim 15, wherein the antistatic agent comprises a surfactant.

17. The filter media of claim 16, wherein the surfactant comprises a non-rewetting thermally degradable surfactant / foaming agent.

18. The filter media of claim 1, wherein the silicone-based coating is applied to the fibers by dipping the fibers into a container containing a silicone-based coating.

19. A gas filter product comprising the filter medium of claim 1.

20. An air filter product for use in a heating, ventilation, and air conditioning (HVAC) system comprising the filter media of claim 1.

21. Filter media, including: a layer comprising continuous fibers having less than about 1% spin finish; and A polysiloxane-based coating on the fiber, wherein the polysiloxane-based coating has an add-on weight of greater than about 1% based on the total weight of the fiber.

22. The filter media of claim 21, wherein the spin finish is about 0%.

23. The filter media of claim 21, wherein the added weight is at least about 5% based on the total weight of the fibers.

24. The filter media of claim 21, wherein the add-on weight is from about 8% to about 10% based on the total weight of the fibers.

25. The filter media of claim 21, wherein the filter media has an E3 filtration efficiency increased by at least about 30% as compared to the E3 filtration efficiency value of the fiber without the polysiloxane-based coating.

26. The filter media of claim 21, wherein the filter media has an E3 filtration efficiency increased by about 35% or more compared to the E3 filtration efficiency value of fibers without the polysiloxane-based coating.

27. The filter media of claim 21, wherein the filter media has an E3 filtration efficiency increased by about 40% or more compared to the E3 filtration efficiency value of fibers without the polysiloxane-based coating.

28. The filter media of claim 21, wherein the filter media has an E2 filtration efficiency increased by about 20% or more compared to an E2 filtration efficiency value of a fiber without the polysiloxane-based coating.

29. The filter media of claim 21, wherein the silicone-based coating comprises at least about 2% silicone compound by weight of the coating.

30. The filter media of claim 21, wherein the silicone-based coating comprises at least about 5% silicone compound by weight of the coating.

31. The filter media of claim 30, wherein the polysiloxane compound is at least about 10% by weight of the coating.

32. The filter media of claim 21, wherein the silicone-based coating comprises a reactive silicone macroemulsion.

33. The filter media of claim 21, wherein the polysiloxane-based coating comprises an amino-functional polydimethylsiloxane.

34. The filter medium of claim 33, wherein the polysiloxane-based coating comprises polyethylene glycol monotridecyl ether.

35. The filter media of claim 34, wherein the amino-functional polydimethylsiloxane comprises from about 30% to about 40% by weight of the coating.

36. The filter medium of claim 34, wherein the polyethylene glycol monotridecyl ether comprises from about 5% to about 10% by weight of the coating.

37. The filter media of claim 21, wherein the continuous fibers are spunbond fibers or meltblown fibers.

38. The filter media of claim 21, wherein the polysiloxane-based coating further comprises an antistatic agent.

39. The filter medium of claim 38, wherein the antistatic agent comprises a surfactant.

40. The filter media of claim 39, wherein the surfactant comprises a non-rewetting thermally degradable surfactant / foaming agent.

41. The filter media of claim 21, wherein the polysiloxane-based coating is applied to the fibers by dipping the fibers into a container containing the polysiloxane-based coating.

42. An air filter product comprising the filter medium of claim 21.

43. A method of preparing a filter medium, the method comprising: Providing multiple fibers; as well as A polysiloxane-based coating is applied to the fibers, wherein the polysiloxane-based coating comprises at least about 2% of a polysiloxane compound, based on the weight of the coating.

44. The method of claim 43, wherein the polysiloxane compound is at least about 5% by weight of the coating.

45. The method of claim 43, wherein the polysiloxane compound is at least about 10% by weight of the coating.

46. ​​The method of claim 43, wherein the add-on weight of the polysiloxane-based coating is greater than about 1% based on the total weight of the fiber.

47. The method of claim 46, wherein the added weight is greater than about 5% based on the total weight of the fibers.

48. The method of claim 46, wherein the added weight is from about 6% to about 10% based on the total weight of the fibers.

49. The method of claim 43, wherein the silicone-based coating is applied by a process selected from the group consisting of spraying the fibers with a silicone-based coating, dipping the fibers into a container containing a silicone-based coating, and applying the silicone-based coating to the fibers in the form of a foam.

50. The method of claim 43, further comprising forming the fibers using a process selected from the group consisting of spunbonding and meltblowing.

51. The method of claim 43, wherein the silicone-based coating is applied as a spin finish.

52. The method of claim 43, wherein the silicone-based coating is applied to the fibers prior to forming the filter media.

53. An air filter made by the method of claim 43.

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