Filter Media and Filters

Abstract

Filter media and filters, such as air filters, residential air filters, commercial air filters, face masks, gas turbine and compressor intake filters, and panel filters, are provided, each comprising a plurality of fibers coated with a silicone-based coating. The silicone-based coating comprises at least about 2% of a silicone compound by weight of the coating. The silicone-based coating may include a reactive silicone macroemulsion and a surfactant. The silicone-based coating improves the filter's capture efficiency of contaminants, particularly those in the E2 and E3 particle group ranges, without compromising other important filter properties, such as cost, lifespan, dust holding capacity, pressure drop, or filter breathability.

Description

[Technical Field]

[0001] Cross-Citation of Related Applications This application claims the benefit of U.S. Provisional Application No. 63 / 406,686, filed September 14, 2022, the entire disclosure of which is incorporated herein by reference for all purposes.

[0002] This disclosure relates generally to filter media with improved performance characteristics, and more particularly to gas filters incorporating a silicon-based coating that improves the efficiency of the filter in capturing contaminants. [Background technology]

[0003] Liquid and gas filters capture many different types of contaminants from air, water, etc. Air filters, for example, typically include a filter media comprising a fibrous or porous material that removes solid particulates such as dust, pollen, mold, and bacteria from the air.

[0004] Two main types of air filter devices include surface filters and depth filters. Surface filters, such as membranes or films, act as a barrier to capture contaminants 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 capacity. High pressure drop reduces airflow through the filter. Low dust loading capacity significantly reduces filter life. As a result, surface filters have been used in a limited number of applications in the air filtration industry.

[0005] Depth filters are commonly used in air filtration devices with medium to high efficiency, low pressure drop, and relatively high dust loading capacity. Depth filters generally use various types of fibers that can be formed into a web or other nonwoven structure with serpentine paths between the fibers through which a gas, such as air, flows. Particulate matter in the gas flowing through the paths in the web is retained on the upstream side of the web, or within the serpentine path of the web, due to the size of the particles relative to the diameter of the paths.

[0006] Traditional residential and commercial air filters, such as HVAC filters, are typically rated by the filter's ability to capture particles between approximately 0.3 μm and 10 μm (approximately 0.3 to 10 microns). This rating, called the Minimum Efficiency Reporting Value, or MERV, is established by the American Society of Heating, Refrigerating, and Air-Conditioning Engineers (ASHRAE). MERV ratings range from 1 to 16, with higher values ​​indicating greater efficiency at capturing specific particles. It is also common to compare efficiency values ​​according to the particle size in the airstream being tested. E3, E2, and E1 values ​​refer to particle efficiency at 3 μm to 10 μm (3 to 10 microns), 1 μm to 3 μm (1 to 3 microns), and 0.3 μm to 1 μm (0.3 to 1 micron), respectively.

[0007] To enhance the particulate contaminant capture efficiency of such air filters, the fibers may be subjected to chemical treatments, additives, or coatings before or after the formation of the filter media. Such coatings may be applied, for example, by spraying, dipping, foaming, or other known manufacturing techniques. For example, to enhance the efficiency of the filter media, silicone-based coatings may be applied to the fibers. Such coatings are described, for example, in U.S. Patent No. 10,279,290. In another example, silicone and / or wax additives are added to the outermost surface of the filter media after it is formed, as described in U.S. Patent No. 8,057,583. Summary of the Invention

[0008] The following presents a simplified summary of the claimed subject matter in order to provide a basic understanding of some aspects of the claimed subject matter. This summary is not an extensive overview of the claimed subject matter, and it is not intended to identify key elements or to limit 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.

[0009] Filtration media and filters, such as gas or liquid filters, face masks, CPAP filters, vacuum bags, cabin air filters, HVAC filters, residential air filters, industrial air filters, intake filters for gas turbines and compressors, panel filters, etc., are provided that include fibers with a silicone-based coating. Systems and methods for manufacturing such filtration media and filters are also provided.

[0010] In one embodiment, a filter medium comprises a layer including one or more fibers coated with a silicone-based coating. The silicone-based coating comprises at least about 2% of a silicone compound by weight of the total coating. Applicant has discovered that directly coating the fibers with the silicone-based coating described herein substantially improves the contaminant capture efficiency of such filters, particularly for contaminants in the E2 and E3 particle size ranges. Furthermore, the coating does not substantially compromise other important filter properties, such as the filter's cost, lifespan, dust holding capacity, pressure drop, or breathability.

[0011] The fibrous structure has a tortuous pore path due to the layered fibrous web. In other words, the pore shape of the nonwoven fabric is not cylindrical. Typically, airflow during filtration passes through the thickness of the filter medium. Therefore, when contaminants that have passed through the filter medium collide with the fiber surface, they are captured or bounced back by the fibers. The filter disclosed herein reduces the amount of particles that bounce back from the fiber surface, allowing more particles to continue contacting the fiber surface, thereby improving particle capture efficiency.

[0012] In embodiments, the silicone-based coating comprises a silicone compound diluted in water or other suitable fluid, the silicone compound comprising at least about 2% by weight of the coating, or at least about 5% by weight of the coating. In exemplary embodiments, the silicone compound comprises about 10% by weight of the coating.

[0013] In embodiments, the weight of the silicone-based coating is greater than about 0.1% of the total fiber weight. In embodiments, the weight of the coating is greater than about 5% of the total fiber weight, or between about 6% and about 10% of the total fiber weight. In other embodiments, the weight of the coating may be greater than 10% of the total fiber weight.

[0014] In an embodiment, the silicone-based coating comprises 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 comprises an amino-functional polydimethylsiloxane and / or a polyethylene glycol monotridecyl ether. In an exemplary embodiment, the amino-functional polydimethylsiloxane comprises about 30 to about 40 weight percent of the coating. In an embodiment, the polyethylene glycol monotridecyl ether comprises about 5 to about 10 weight percent of the coating.

[0015] The fibers can be staple fibers or continuous fibers. Prior to application of the coating, the fibers can be virgin (i.e., without a spin finish). Alternatively, prior to application of the coating, the fibers can be spin finished. In certain embodiments, the virgin continuous fibers are spunbond or meltblown fibers. In other embodiments, the staple fibers have less than about 2% conventional spin finishing.

[0016] In some embodiments, the silicone-based coating further comprises an antistatic agent. The antistatic agent may comprise a cationic antistatic agent, an anionic antistatic agent, a quaternary antistatic agent, or a surfactant. The surfactant may comprise a non-rewetting, thermally decomposable surfactant / foaming agent.

[0017] The fibres can be man-made or natural. Suitable materials for the fibres include 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, cycloolefin copolymers or fluorinated polymers, polytetrafluoroethylene, perfluoroethylene and hexafluoropropylene, or copolymers with PVDF (such as P(VDF-TrFE)) or terpolymers (such as P(VDF-TrF Examples of suitable fiber materials include, but are not limited to, polyethylene terephthalate (PE-CFE), propylene, polyimides, polyetherketones, cellulose esters, nylons and polyamides, polymethacrylates, polymethyl methacrylates, polyoxymethylene, polysulfonates, acrylics, styrenated acrylics, preoxide 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. In some embodiments, bicomponent staple fibers such as HDPE / PET, PP / PET, CoPET / PET, etc. are preferred. In some embodiments, finish-free bicomponent fibers can be produced using bicospunbond technology, followed by a coating.

[0018] The fibers may have a thickness appropriate for the application. In some embodiments, the fibers have at least one dimension ranging from about 1 μm to about 10,000 μm (about 1 to about 10,000 micrometers), or from about 1 μm to about 1,000 μm (about 1 to about 1,000 micrometers), or from about 10 μm to 100 μm (about 10 to 100 micrometers). Fiber thickness may also be measured in denier, which is a measure of the linear density of the fiber. In some embodiments, the fibers may have a linear density of about 9 tex to about 90 tex (about 1 denier to about 10 denier). The fibers may be configured as a gradient density medium, with pore size decreasing from the upper surface (upstream) to the lower surface (downstream) of the filter, or vice versa, to improve collection efficiency and dust holding capacity.

[0019] In some embodiments, the fibrous layer may be composed of a "high loft" nonwoven material, including spunbond or air-through bonded carded nonwoven fibers. As used herein, the term "high loft" means that the void volume is greater than the total solids volume. In air-through bonded carded nonwoven fibers, the loft of the fibrous layer may be controlled by various means known to those skilled in the art.

[0020] In certain embodiments, the fiber is a biocomponent fiber having a core and a sheath. In embodiments, the core is eccentric relative to the sheath. In other embodiments, the core is concentric with the sheath.

[0021] In certain embodiments, the filter media comprises a nonwoven material, including a substrate, sheet, layer, film, apertured film, mesh, or other medium, comprising fibers coated with a silicone-based coating.

[0022] In another aspect, an air filter, such as an HVAC filter, is provided having one or more fibers coated with a silicone-based coating comprising a silicone compound diluted in water or other suitable fluid, the silicone compound comprising at least about 2% by weight of the coating, or at least about 5% by weight of the coating. In an exemplary embodiment, the silicone compound comprises about 10% by weight of the coating.

[0023] Filter media comprising fibers coated with the silicone-based coating described herein can be used to manufacture supported, freestanding, pleated, or flat (non-pleated) air or HVAC filters having a minimum efficiency rating of at least MERV 6 per ASHRAE 52.2. In some embodiments, the MERV rating is MERV 7, MERV 8, MERV 9, or even MERV 10.

[0024] In embodiments, the filter media has an E3 filtration efficiency of about 30% or more compared to the E3 filtration efficiency value of fibers without the silicone-based coating, or has an E3 filtration efficiency of at least about 35% or more compared to the E3 filtration efficiency value of fibers without the silicone-based coating, or has an E3 filtration efficiency of at least about 40% or more compared to the E3 filtration efficiency value of fibers without the silicone-based coating.

[0025] In embodiments, the filter media has an E2 filtration efficiency2 improvement of about 20% or more compared to the E2 filtration efficiency value of a fiber without the silicone-based coating.

[0026] In embodiments, the filter has a pressure drop that is less than 10% greater than the pressure drop of a filter without the silicone-based coating. In embodiments, the pressure drop is less than 5%, less than 1%, or less than 0.5% of the pressure drop of a filter without the silicone-based coating.

[0027] In embodiments, the filter has an air permeability within 5% of the air permeability of a filter without the silicone-based coating. In embodiments, the air permeability is less than 1% of the air permeability of a filter without the silicone-based coating.

[0028] In certain embodiments, the MERV rating of the filter media can be improved simply by applying a silicone-based coating. In some of these embodiments, the filter media has an E3 particle removal 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.

[0029] The filter may further include a substantially rigid support layer adhered to the filter media. The fabric may comprise an extruded film having one or more openings for flow or passage of liquid. For example, the openings may be hexagonal, circular, square, or diamond shaped.

[0030] The filter may include pleats. For example, the fibrous layer may include at least one fold to form a pleat in the fibrous layer. In another example, the filter further includes a plurality of pleats extending across a surface of the fibrous layer. The fibrous layer may not be pleated.

[0031] In certain embodiments, the fibers in the filter media may be electrostatically charged, for example, to capture contaminants by both mechanical and electrostatic filtration. The electrostatic or electret fibers may be, for example, a high-loft triboelectric filter media produced by carding and needling.

[0032] In another aspect, a method for manufacturing a filter media includes providing a plurality of fibers and applying a silicone-based coating to the fibers. The coating comprises at least about 2% or at least 5% by weight of the coating of a silicone compound. In an exemplary embodiment, the silicone compound comprises about 10% by weight of the coating.

[0033] The coating is applied directly to the fibers after or before the formation of the fibrous web. Applicant has found that applying the coating directly to the fibers improves the overall efficiency of the filter media, particularly in capturing contaminants in the E2 or E3 particle groups.

[0034] In some embodiments, the weight add-on of the silicone-based coating is greater than about 1% based on the total fiber weight, and in certain embodiments, the weight add-on is greater than about 5% based on the total fiber weight, or between about 6% and about 10% based on the total fiber weight.

[0035] In embodiments, the silicone-based coating comprises 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, etc. In an exemplary embodiment, the reactive silicone macroemulsion comprises an amino-functional polydimethylsiloxane and / or polyethylene glycol monotridecyl ether.

[0036] The fibers may be produced by any suitable method, including, but not limited to, meltblown, spunbonded, spunlaced, bicomponent spunbonded, thermally bonded, carded, airlaid, wetlaid, extrusion, co-molded, needlepunched, stitched, hydroentangled, etc. In certain embodiments, bare continuous fibers are formed by a process selected from the group consisting of spunbonded and meltblown. In other embodiments, staple fibers incorporating the filter media are formed by carded, airlaid, wetlaid, or similar processes.

[0037] In embodiments, the silicone-based coating is applied by any suitable process, including, but not limited to, spraying the silicone-based coating onto the fiber, dipping the fiber into a container containing the silicone-based coating, and applying the silicone-based coating to the fiber as a foam.

[0038] The coating can be applied as a spin finish, can be applied after the spin finish has been applied, can be applied to bare fibers without a spin finish, or can be applied to staple fibers that have already been applied with a common spin finish.

[0039] The enumeration herein of desirable objectives met by various embodiments of the present specification is not intended to imply or suggest that any or all of these objectives, individually or collectively, are present as essential features of either the most general embodiment of the present specification or its more specific embodiments. DETAILED DESCRIPTION OF THE INVENTION

[0040] This description illustrates exemplary embodiments and should not be construed as limiting, with the claims, including equivalents, defining the scope of this specification. Various mechanical, configurational, structural, and operational changes may be made without departing from the scope of this specification and the claims, including equivalents. In some instances, well-known structures and techniques have not been shown or described in detail to avoid obscuring the description. The same numbers in two or more figures represent the same or similar elements. Furthermore, elements and related aspects described in detail with reference to one embodiment may, to the extent practical, be included in other embodiments not specifically shown or described. For example, an element may be described in detail with reference to a first embodiment but not with reference to a second embodiment, and yet the element may be claimed as included in the second embodiment. Furthermore, illustrations herein are for illustrative purposes only and do not necessarily reflect the actual shape, size, or dimensions of the system or illustrated components.

[0041] It should be noted that, as used in this specification and the appended claims, the singular forms "a," "an," "the," and the use of words in the singular include plural referents unless expressly and clearly limited to one referent. As used herein, the term "include" and its grammatical variations are intended to be non-limiting, and the enumeration of items in a list does not exclude other similar items that may be substituted for or added to the listed items.

[0042] Unless otherwise indicated, any quantitative value is approximate, whether or not preceded by terms such as "about" or "approximately." The materials, methods, and examples described herein are illustrative only and are not intended to be limiting.

[0043] Filter media and filters, such as gas or liquid filters, face masks, CPAP filters, vacuum bags, cabin air filters, HVAC furnace filters, residential air filters, commercial air filters, gas turbine and compressor intake filters, panel filters, etc., are provided that include fibers with a silicone-based coating. Systems and methods for manufacturing such filters are also provided.

[0044] The silicone-based coating comprises a silicone compound diluted in water or other suitable fluid, with the silicone compound comprising at least about 2% by weight, or at least about 5% by weight, of the coating. In an exemplary embodiment, the silicone compound comprises about 10% by weight of the coating. In an exemplary embodiment, the silicone compound comprises a silicone material, a surfactant, and water. The silicone and surfactant together may comprise about 10% by weight of the total coating.

[0045] Applicants have discovered that by applying the silicone-based coating described herein directly to the fibers (rather than applying a coating to the outer surface of an already formed filter media), the contaminant capture efficiency of such filters, particularly those in the E2 and E3 particle size ranges, is significantly improved. Moreover, the coating does not substantially compromise other important filter properties, such as the filter's cost, lifespan, dust holding capacity, pressure drop, or breathability.

[0046] The weight of the silicone-based coating can be greater than about 0.1% by weight of the total fiber. In exemplary embodiments, the weight of the coating is greater than about 5% by weight of the total fiber, or between about 6% and about 10% by weight of the total fiber.

[0047] In an embodiment, the silicone-based coating comprises a reactive silicone macroemulsion. Silicone emulsions are insoluble silicones dispersed substantially uniformly in water with the aid of surfactants. Silicone emulsions may include, for example, dimethylsilicone emulsions, amino-type silicone emulsions, organofunctional silicone emulsions, resin-type silicone emulsions, film-forming silicone emulsions, and the like. In an exemplary embodiment, the reactive silicone macroemulsion comprises an amino-functional polydimethylsiloxane and / or polyethylene glycol monotridecyl ether. In an embodiment, the amino-functional polydimethylsiloxane comprises about 30 to about 40 weight percent of the coating. In an embodiment, the polyethylene glycol monotridecyl ether comprises about 5 to about 10 weight percent of the coating.

[0048] The fibers may be staple or continuous fibers. Prior to coating, the fibers may be in an untreated state (i.e., without a spin finish). Prior to coating, the fibers may include a spin finish. The spin finish may include, but is not limited to, lubricants, emulsifiers, antistatic agents, antibacterial agents, tackifiers, wetting agents, etc. Other organic liquids, such as alcohols or mixtures of organic liquids, may be added to the spin finish. The spin finish may be applied, for example, during fiber carding, during the melt spinning process, or during fiber drawing, crimping, or cutting.

[0049] In embodiments, the silicone-based coating further comprises an antistatic agent, which may comprise a surfactant, which may comprise a non-rewetting thermally decomposable surfactant / foaming agent.

[0050] In certain embodiments, the filter media comprises a nonwoven material, including a substrate, sheet, layer, film, apertured film, mesh, or other media containing fibers.

[0051] The nonwoven layers described herein may include structures in which individual fibers or threads are interlaid, interlocked, or bonded to one another. Nonwovens may include sheet or web structures bonded by mechanically, thermally, or chemically entangling fibers or filaments (and perforating films). They may be substantially flat, porous sheets made directly from discrete fibers, 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, needlepunched, stitched, hydroentangled, and other fibers, layers, or webs.

[0052] In certain embodiments, the fibrous layer may comprise a knitted material and / or a woven material. The knitted material may comprise any knit pattern suitable for the desired application. Knitted materials suitable for filter applications include weft knits, warp knits, knitted mesh panels, compressed knit mesh, etc. Woven textiles suitable for filter applications include fibrous filter media such as monofilament woven fabrics, multifilament woven fabrics, nylon mesh, polyester mesh, polypropylene mesh, etc. Woven textiles may be used, for example, in mesh filter press cloths, woven filter pads and other die-cut pieces, centrifuge filter bags, liquid filter bags, dust collection bags, bed dryer bags, rotary drum filters, filter belts, leaf filters, roll media, etc.

[0053] In some embodiments, the nonwoven material may comprise short-cut fibers and / or intertwined or entangled filaments. As used herein, short-cut fibers refer to fibers having a finite length. As used herein, filaments refer to fibers having a substantially continuous length. In some embodiments, the fibers may comprise short-cut coarse fibers, microfibers, and / or ultrafine fibers. As used herein, "ultrafine fibers" refers to fibers having a diameter of less than 1 μm (1 micron), "coarse fibers" refers to fibers having a diameter of more than 10 μm (10 microns), and microfibers refers to synthetic fibers having a diameter of less than 10 μm (10 microns).

[0054] Contemplated fibers may be made by any method including, but not limited to, air-laid or dry-laid, carded, spinneret, gel-spinning, melt-spinning, wet-spinning, dry-spinning, islands-in-the-sea staple or spunbond, segment-pie staple or spunbond, and other methods. 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 complete disclosures of which are incorporated herein by reference for all purposes.

[0055] Fibers contemplated by the present invention may have a variety of cross-sectional shapes, including, but not limited to, round, kidney bean, dogbone, trilobal, barbell, bow tie, star, Y-shaped, etc. These and / or other conventional shapes may be used in embodiments to achieve desired performance characteristics. The fibers remain bonded to one another through thermal and chemical bonding, intertwining, and through the use of bonding agents such as adhesives.

[0056] The fibers may be man-made or natural. Suitable materials for the fibers include 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, cycloolefin copolymers or fluorinated polymers, polytetrafluoroethylene, perfluoroethylene and hexafluoropropylene, or copolymers with PVDF such as P(VDF)-TrFE or P(VDF-TrFE-CFE). Examples of suitable fiber materials include, but are not limited to, terpolymers such as propylene, polyimides, polyetherketones, cellulose esters, nylons and polyamides, polymethacrylates, polymethyl methacrylates, polyoxymethylene, polysulfonates, acrylics, styrenated acrylics, preoxide acrylics, fluorinated acrylics, vinyl acetates, vinyl acrylics, ethylene vinyl acetate, styrene butadiene, ethylene / vinyl chloride, vinyl acetate copolymers, latex, polyester copolymers, carboxylated styrene acrylics or vinyl acetates, epoxies, acrylic multipolymers, phenolics, polyurethanes, cellulose, styrenes, or any combination thereof. Other conventional fiber materials are also contemplated. In some embodiments, the coating is applied to bicomponent fibers. Such bicomponent fibers may be produced by melt-spinning, spunbonding, or melt-blowing processes.

[0057] Fibers can be found in a variety of sizes, typically ranging from about 1 μm to about 1000 μm (about 1 to about 1000 microns) in diameter and about 1.27 cm to 7.62 cm (about 0.5 to 3 inches) in length. Fibers can be configured as a gradient density media, with pore size decreasing from the top (upstream) to the bottom (downstream) surface of the filter, to improve collection efficiency and dust holding capacity. Alternatively, this configuration can be reversed.

[0058] Fibers in the media may remain bonded to other fibers through thermal bonding, chemical bonding, or entanglement. Especially in mechanical filtration, bicomponent fibers may be used, which are formed by extruding two polymers through 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), HDPE / PET, PP / PET, CoPET / PET, etc.

[0059] In some embodiments, the fibrous layer may comprise a "high loft" nonwoven material, including spunbond or air-through-bond carded nonwoven fibers. As used herein, the term "high loft" refers to a void volume greater than the total solids volume. In air-through-bond carded nonwoven fibers, the loft of the fibrous layer may be controlled by various means known to those skilled in the art. For example, loft may be increased by applying less compressive force to the medium during bonding. In another example, high loft nonwoven materials may be produced using fibers having a thickness greater than 27 tex (3 denier), e.g., 45 tex (5 denier) or greater, 54 tex (6 denier) or greater (discussed in more detail below). In other embodiments, loft may be increased by using eccentric biocomponent fibers.

[0060] The fibers may have a thickness suitable for the application. In some embodiments, the fibers have at least one dimension ranging from about 1 to about 10,000 μm (about 1 to about 10,000 micrometers), about 1 μm to about 1,000 μm (about 1 to about 1,000 micrometers), or about 10 μm to 100 μm (about 10 to 100 micrometers). Fiber thickness may be measured in denier, which is a measure of the linear density of a fiber. In some embodiments, the linear density of a fiber may be about 9 tex to about 90 tex (about 1 denier to about 10 denier).

[0061] In certain embodiments, the filter media may include at least two different fiber thicknesses or linear densities, providing at least two different filter layers within the same filter media. In certain embodiments, the filter media may include three or more separate sections or layers with different denier fiber ranges within each section.

[0062] In some embodiments, the fibrous layer may include additives such as antibacterial and / or antiviral compositions, such as organic compounds containing silver, zinc, copper, organosilicon, tributyltin, chlorine, bromine, or fluorine compounds.

[0063] The fibers may include biocomponent fibers, which are two or more different fibers bonded together. The fibers may be comprised of the same or different materials.

[0064] In certain embodiments, the fibers can be electrostatically charged, e.g., contaminants are captured by both mechanical and electrostatic filtration. Fibers can be electrostatically charged using triboelectric methods, corona discharge, electrospinning, hydrocharging, charging bars, or other known methods. Corona charging is suitable for charging monopolymer fibers, fiber blends, or woven fabrics. Tribocharging may be suitable for charging fibers with different electronegativities. Electrostatic or electret fibers can include high-loft triboelectric filter media produced by carding and needling. Electrospinning combines polymer charging and fiber spinning in a single process. One suitable method for triboelectric charging is described in U.S. Pat. No. 9,074,301, the disclosure of which is incorporated herein by reference for all purposes.

[0065] In certain embodiments, the nonwoven materials discussed herein may be incorporated as part of a filter device that captures or absorbs contaminants, such as liquid filters, gas filters for home and commercial air filtration (e.g., HVAC), surgical masks, or other face coverings. The filter 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 may be designed to remove many different types of contaminants from air, water, etc.

[0066] In some embodiments, the filter media may be creased, pleated, or folded into a pleated filter. The pleats may be formed by various conventional pleating processes, including, but not limited to, bar pleating, rotary pleating, and star gear pleating. The filter includes one or more support layers adhered to the filter media. In some embodiments, a polymer layer, membrane, or film is provided with one or more openings for gas or liquid passage therethrough. In other embodiments, the material constitutes a flexible surface layer for a finger bandage pad, face mask, or the like.

[0067] In one embodiment, the nonwoven material is incorporated into air filters that remove airborne particles and contaminants, such as HEPA filters (i.e., pleated mechanical air filters), ultraviolet filters, electrostatic filters, washable filter media filters, spun glass filters, pleated and non-pleated air filters, activated carbon filters, pocket filters, V-bank compact filters, filter sheets, flat cell filters, filter cartridges, etc. These fibers can comprise the filter media of the air filter and can be supported by a support or scrim layer or can be included in other layers or materials.

[0068] Traditional residential and commercial air filters, such as HEPA filters and pleated filters, are typically rated by the filter's ability to capture particles between approximately 0.3 μm and 10 μm (approximately 0.3 to 10 microns). This rating, called the Minimum Efficiency Reporting Value (MERV), is established by the American Society of Heating, Refrigerating, and Air-Conditioning Engineers (ASHRAE). MERV ratings range from 1 to 16, with higher values ​​indicating greater efficiency at capturing specific particles. It is also common to compare efficiency values ​​according to the particle size in the airstream being tested. E3, E2, and E1 values ​​represent particle efficiency at 3 μm to 10 μm (3 to 10 microns), 1 μm to 3 μm (1 to 3 microns), and 0.3 μm to 1 μm (0.3 to 1 micron).

[0069] The MERV ratings of the filter media discussed herein depend 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 the pleats (if any), etc. Similarly, the pressure drop across the filter media also depends on many factors, including those mentioned above.

[0070] In certain embodiments, filter media comprising fibers coated with the silicone-based coatings described herein may be used to manufacture supported, freestanding, or flat-sheet (non-pleated) air or HVAC filters having a minimum efficiency rating (MERV) under ASHRAE 52.2 of at least MERV 6. In some embodiments, the MERV rating is MERV 7, MERV 8, MERV 9, or MERV 10.

[0071] In certain embodiments, the silicone-based coating improves the efficiency of the filter media in capturing E2 and / or E3 particle group contaminants compared to filter media without the silicone-based coating. In these embodiments, the MERV rating of the filter media may be improved solely by the application of the silicone-based coating. In some of these embodiments, the filter media's E3 particle removal efficiency is at least about 5 points, at least about 10 points, at least 18 points, or at least about 30 points. The MERV rating can increase from MERV 7 to MERV 8, or from MERV 8 to MERV 9, or from MERV 7 to MERV 9, or even to MERV 10.

[0072] In certain embodiments, the fibrous layer is a filter media for a gas filter, such as an HVAC filter. In embodiments, the filter media exhibits an improvement in E3 filtration efficiency of about 30% or more compared to the E3 filtration efficiency value of fibers without the silicone-based coating, or about 35% or more compared to the E3 filtration efficiency value of fibers without the silicone-based coating, or about 40% or more compared to the E3 filtration efficiency value of fibers without the silicone-based coating.

[0073] In embodiments, the filter media exhibits an E2 filtration efficiency improvement of about 20% or more compared to the E2 filtration efficiency value of a fiber without the silicone-based coating.

[0074] In embodiments, the filter has a tested pressure drop that is less than 10% of the pressure drop of a filter without the silicone-based coating. In embodiments, the pressure drop is less than 5%, less than 1%, or less than 0.5% of the pressure drop of a filter without the silicone-based coating.

[0075] In embodiments, the air permeability of the filter is within 5% of the air permeability of a filter without the silicone-based coating. In embodiments, the air permeability is less than 1% of the air permeability of a filter without the silicone-based coating.

[0076] Other types of filters that can be developed using the nonwoven materials disclosed herein include conical filter cartridges, square end cap filter cartridges, pocket filters, V-bank compact filters, panel filters, flat cell filters, pleated or non-pleated bag cartridge filters, and the like.

[0077] In certain embodiments, the nonwoven material may be included in a thin film or layer containing apertures, pores, or perforations. The apertures may be embossed into a pattern (e.g., circles, diamonds, hexagons, rectangles, triangles, rectangles, etc.) and then stretched until apertures form in the thinned areas formed by the embossing. Such apertured substrates may be formed from many polymers, such as polypropylene, polyethylene, high-density polyethylene ("HDPE"), etc. The polymer layer may 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 onto the substrate in a roll-to-roll process.

[0078] The fibers may be made by any suitable process, including, but not limited to, meltblown, spunbonded or spunlaced, thermally bonded, carded, airlaid, wetlaid, extruded, co-molded, needlepunched, stitched, hydroentangled, and the like.

[0079] In certain embodiments, bare continuous fibers are formed by a process selected from the group consisting of spunbonding and meltblown processes. In one example, the system includes a spunbonding line, where molten polymer is spun and the molten filaments are drawn to form filaments. The filament fiber bundles are separated, spread, and then stacked on a net to form a web. The fibers are bundled into a sheet by thermal bonding and embossing. The fiber stream can be introduced, for example, before the attenuation zone or before the bonding (consolidation) process.

[0080] As another example, the fibers may be formed using a meltblowing die. Examples of suitable meltblowing dies that can be used to produce nonwoven fabrics are described in detail in U.S. Patent Nos. 6,972,104, 8,017,534, 7,772,456, and U.S. Patent Application No. 20200216979A1, the entire disclosures of which are incorporated herein by reference for all purposes.

[0081] In other embodiments, the staple fibers are formed by carding, air laying, wet laying, or similar processes. In one example, a system may include one carding machine or two carding machines arranged in series with one another. The staple fibers are processed into a continuous fibrous web by opening, blending, and consolidation. After the fibrous web is formed by carding, a secondary bonding process may be used to increase the integrity and strength of the fibrous web. This bonding process may be achieved by chemical, thermal, or mechanical methods.

[0082] Preferably, the coating is applied directly to the fibers prior to forming the fibrous web. Applicants have found that applying the coating directly to the fibers (rather than to the surface of an already formed filter media) improves the overall efficiency of the filter media, particularly the capture efficiency of contaminants in the E2 or E3 particle groups.

[0083] In embodiments, the silicone-based coating is applied by any suitable process, including, but not limited to, spraying the silicone-based coating onto the fiber, dipping the fiber into a container containing the silicone-based coating, and applying the silicone-based coating to the fiber as a foam.

[0084] The coating can be applied as a spin finish, applied after the spin finish is applied, or the coating can be applied to bare fibers without the spin finish. [Example]

[0085] Applicant conducted four separate experiments using various fibers in filter media. The fibers were tested before and after applying a silicone-based coating to the fibers. The tests measured the pressure drop across each filter media and the initial fractional efficiency of the filter media for three separate particle groups: (1) E1 particles, which have a particle size of approximately 0.3 μm to 1 μm (approximately 0.3 to 1 micron); (2) E2 particles, which have a particle size of approximately 1 μm to 3 μm (approximately 1 to 3 microns); and (3) E3 particles, which have a particle size of approximately 3 μm to approximately 10 μm (approximately 3 to 10 microns). Tests were conducted at a filtration rate of 54.864 m (180 ft) per minute. All MERV ratings reported herein (based on flat plate fractional efficiency tests) are predicted MERV ratings.

[0086] The coatings included a silicone compound in a reactive silicone macroemulsion, a non-wetting, thermally decomposable surfactant / blowing agent, and water. The fabric was pad-finished (or in some cases, no finish was applied), and the coating was applied to the fabric and then dried at 240°F for 3 minutes. In the first test, the coating contained only 10 g of silicone compound, 1 g of surfactant, and 989 g of water. Thus, the coating contained approximately 1% silicone compound by weight. In the second, third, and fourth tests, the ratio of silicone compound to surfactant was increased to 100 g of silicone compound and 10 g of surfactant per 890 g of water (i.e., approximately 10% silicone compound by weight).

[0087] Tables 1 and 2 below show the results of the first test. This test was performed on three different samples, and the average values ​​are shown. Note that G6 spin finish is Fibervisions' standard spin finish, while G8 is a specialized finish for filtration applications. Both spin finishes are applied during fiber manufacturing. Fibers coated with G8 spin finish exhibit higher efficiency compared to fibers coated with G6 spin finish. Staple fiber is defined as a relatively short, non-continuous fiber. Filter media were tested both before and after coating. The filter media was made from bicomponent fibers coated with G6 spin finish. The fibers were carded and then thermally bonded. The coating formulation included 1% silicone compound, 0.1% surfactant, and 98.9% water. As shown in Table 2, the coating improved the filter media efficiency for all three particle sizes, with the E3 particle size exhibiting the greatest increase of over 12% (from 55.5 to 62.4). However, this increase was insufficient to change the MERV rating of the filter media, and the change in pressure drop was negligible. Table 1 TIFF2025532042000001.tif26116 Table 2 TIFF2025532042000002.tif21138

[0088] Tables 3-5 show the results of the second test. This test was conducted on five different staple fiber samples with a G6 finish on MERV 7 filter media. The results in Tables 3-5 are averages for all five samples. The coating was increased to 10% silicone compound, 1% surfactant, and 89% water. As shown, the efficiency of the filter media increased with the coating in all three particle sizes, with an increase of 18.8 points, or over 35%, observed for the E3 particle size. This increased the overall MERV rating of the filter from MERV 7 to MERV 8. There was only a slight increase in pressure drop. Air permeability decreased by only 0.9%. The basis weight change due to the coating was 8.3%. Thus, the coating significantly improved the filtration efficiency of the filter media in the E3 zone without significantly increasing pressure drop or air permeability. Furthermore, 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). Table 3 TIFF2025532042000003.tif31140 Table 4 TIFF2025532042000004.tif21138 Table 5 TIFF2025532042000005.tif21137

[0089] Comparing the results of the first and second tests shows that increasing the weight percent of silicone compound in the coating significantly increases the efficiency of the filter media.

[0090] Tables 6 and 7 show the results of the third test. In this test, two types of filter media were tested. The first filter media contained five discontinuous or staple fiber samples, half of which had already been coated with G8 spin finish (labeled "Staple"). The results in Tables 6 and 7 represent the average values ​​for all five samples. As shown, the coating did not improve the efficiency of the filter media for particle sizes E1 or E2, but it did slightly increase the efficiency of the E3 particle size by 6.2%, improving the filter's overall MERV rating from MERV 8 to MERV 9.

[0091] The second filter media included five continuous fiber samples (labeled CON) manufactured using a spunbond process. These fibers were bare fibers without any filtration coating or spin finish. The results in Tables 6 and 7 represent the average values ​​for all five samples. As shown, the coating significantly increased the filter media efficiency by 23% for the E2 particle group and 23.8 points for the E3 particle group, 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 decreased by only 1.6%. The basis weight change due to the coating was 6.8%. Thus, the coating significantly improved the filtration efficiency of the E2 and E3 particle group filter media with minimal impact on pressure drop or air permeability. Table 6 TIFF2025532042000006.tif41140 Table 7 TIFF2025532042000007.tif26116

[0092] A third test showed that the silicone-based coating was more effective than bare fibers that had not been coated before the silicone-based coating was applied.

[0093] Tables 8-11 show the results of the fourth test. In this test, two samples of each of several bicomponent spunbond continuous fibers (each fiber was labeled 5-2, 4B3, etc.) were tested. Results are the average of the two samples for each fiber. Table 8 shows the sample weight, basis weight, thickness, and air permeability for each fiber before the silicone-based coating was applied. All samples were approximately 12 inches (30.48 cm) wide and long, with an area of ​​929.03 cm. 2 (144 square inches (in 2 )) was. Table 8 TIFF2025532042000008.tif73140

[0094] Tables 9-11 show the filtration efficiency and pressure drop results for each fiber before and after coating the fiber with a silicone-based compound. As shown, the coating slightly improved filtration of E2 particles and significantly improved filtration of E3 particles. The average increase across all samples (Table 11) was 6.4% for E2 particle filtration and 41.9% (or 22.8 percentage points) for E3 particle filtration. Of all samples, E3 particles showed the smallest change in efficiency, but still had a 32.83% increase.

[0095] The silicone-based compound reduced the average pressure drop by only 4.9%, and the maximum pressure drop reduction was 12.9%. Thus, the coating significantly improved the filtration efficiency of the E3 particle group filter media without significantly increasing the overall filter pressure drop. Table 9: Before treatment TIFF2025532042000009.tif73148 Table 10: After treatment TIFF2025532042000010.tif67138 Table 11 TIFF2025532042000011.tif78139

[0096] In another embodiment, the filter may include nanoparticles incorporated into the fiber layer or filter media. As used herein, the term "nanoparticle" refers to any particle having a dimension of less than 1 μm (1 micron) in at least one axis or dimension. For example, a fiber having a diameter or width of less than 1 μm (1 micrometer) and a length of more than 1 μm (1 micrometer) is a nanoparticle herein. Nanofibers can have a continuous length or can have discrete lengths, such as from 1 μm to 100,000 μm (1 to 100,000 microns), preferably from about 100 μm to 100,000 μm (about 100 to 100,000 microns).

[0097] In some embodiments, the nanoparticles are dispersed "depth-wise" within the fiber layer. As used herein, the term "depth-wise" means that the nanoparticles are dispersed beyond a first surface of the fiber layer, with at least some of the nanoparticles being disposed within the internal structure of the fiber layer or medium between the first and second opposing surfaces. In some 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 through a portion of the medium, from the first surface to a location between the first and second surfaces.

[0098] To utilize the triboelectric effect to enhance particle removal, nanoparticles can be selected that have different triboelectric properties than the first or second fibers. In this manner, the nanoparticles are formed in an electric field, making them less susceptible to chemical contamination that can suppress triboelectric properties. Nanoparticles with different adsorption or surface charge characteristics than the coarse fibers can also be used, for example, in oil and water filtration. This difference can be used to enhance or create local electric field gradients within the filter media, enhancing particle removal. The nanoparticles and the coarse fibers can have different wetting characteristics.

[0099] The nanoparticles may comprise any suitable material, such as glass, biosoluble glass, ceramic materials, acrylics, carbon, metals such as alumina, polymers (such as nylon and polyethylene terephthalate), polyvinyl chloride (PVC), polyolefins, polyacetals, polyesters, cellulose ethers, polyalkylene sulfides, poly(arylene oxides), polysulfones, modified polysulfone polymers and polyvinyl alcohols, polyamides, polystyrenes, polyacrylonitriles, polyvinylidene chloride, polymethyl methacrylates, polyvinylidene fluorides, and any combination thereof.

[0100] In some embodiments, the nanoparticles are bonded to the fibers by mechanical entanglement. This mechanical bond may be reinforced by an adhesive or binder. In certain embodiments, the nanoparticles are not crimped (i.e., they do not contain the pronounced wavy, bent, curled, coiled, sawtooth, or similar shapes associated with nanoparticles in their relaxed state). In other embodiments, the nanoparticles may have a crimped body structure with discrete lengths. For example, when these crimped nanofibers with discrete lengths are attached to fibers, the nanofibers entangle with each other and also firmly adhere to and around the fibers to form the modified fibers. In other embodiments, attachment of the nanofibers to the microfibers is achieved by electrostatic attraction and / or van der Waals forces between the fibers and the nanoparticles. A more complete description of filter media incorporating nanoparticles is provided in commonly assigned, co-pending International Patent Application No. PCT / US2023 / 17967, filed April 7, 2023, the complete disclosure of which is incorporated herein by reference for all purposes.

[0101] While the devices, systems, and methods have been described in detail herein according to certain preferred embodiments thereof, many modifications and variations thereon may be made by those skilled in the art. Accordingly, the above description is not intended to be limiting, but should be construed to include such obvious variations as may be apparent, and is limited only by the spirit and scope of the appended claims.

[0102] For example, in a first aspect, a first embodiment is a filter media comprising a layer including one or more fibers, the fibers coated with a silicone-based coating including at least about 2% by weight of the coating of a silicone compound.

[0103] A second embodiment is the first embodiment, wherein the silicone compound is at least about 5% by weight of the coating.

[0104] A third embodiment is a combination of any of the first two embodiments, wherein the silicone compound is at least about 10% by weight of the coating.

[0105] A fourth embodiment is a combination of any of the first three embodiments, wherein the weight add-on of the silicone-based coating is greater than about 1% based on the weight of the total fiber.

[0106] A fifth embodiment is any combination of the first four embodiments, wherein the weight add-on is greater than about 5% based on the total fiber weight.

[0107] A sixth embodiment is any combination of the first five embodiments, wherein the weight add-on is from about 6% to about 10% based on the total fiber weight.

[0108] A seventh embodiment is any combination of the first six embodiments, wherein the fibers are staple fibers.

[0109] An eighth embodiment is any combination of the first seven embodiments, wherein the fibers are continuous fibers.

[0110] A ninth embodiment is any combination of the first eight embodiments, wherein the continuous fibers are spunbond fibers or meltblown fibers.

[0111] A tenth embodiment is any combination of the first nine embodiments, wherein the silicone-based coating comprises a reactive silicone macroemulsion.

[0112] An eleventh embodiment is a combination of any of the first ten embodiments, wherein the silicone-based coating comprises an amino-functional polydimethylsiloxane.

[0113] A twelfth embodiment is a combination of any of the first eleven embodiments, wherein the silicone-based coating comprises polyethylene glycol monotridecyl ether.

[0114] A thirteenth embodiment is any combination of the first twelve embodiments wherein the amino-functional polydimethylsiloxane comprises about 30 to about 40 weight percent of the coating.

[0115] A fourteenth embodiment is any combination of the first thirteen embodiments wherein the polyethylene glycol monotridecyl ether comprises about 5 to about 10 weight percent of the coating.

[0116] A fifteenth embodiment is a combination of any of the first fourteen embodiments, wherein the silicone-based coating further comprises an antistatic agent.

[0117] A sixteenth embodiment is a combination of any of the first fifteen embodiments, wherein the antistatic agent comprises a surfactant.

[0118] A seventeenth embodiment is a combination of any of the first sixteen embodiments wherein the surfactant comprises a non-rewetting thermally decomposable surfactant / foaming agent.

[0119] An eighteenth embodiment is a combination of any of the first seventeen embodiments, wherein the silicone-based coating is applied to the fiber by dipping the fiber into a container containing the silicone-based coating.

[0120] In a second aspect, a gas filter product comprises the filter media of any combination of the first 18 embodiments.

[0121] In a third aspect, an air filter product for use in a heating, ventilation, and air conditioning (HVAC) system comprising the filter media of any combination of the first 18 embodiments.

[0122] In a fourth embodiment, the filter media comprises a layer comprising continuous fibers having a spin finish of less than about 1% and a silicone-based coating on the fibers, wherein the weight add-on of the silicone-based coating is greater than about 1% based on the weight of the total fibers.

[0123] The second embodiment is the first embodiment, with a spin finish of about 0%.

[0124] A third embodiment is any combination of the first two embodiments, wherein the weight add-on is at least about 5% based on the total fiber weight.

[0125] A fourth embodiment is any combination of the first three embodiments, with the weight add-on being from about 8% to about 10% based on the total fiber weight.

[0126] A fifth embodiment is any combination of the first four embodiments, wherein the filter media has an E3 filtration efficiency improvement of at least about 30% compared to the E3 filtration efficiency value of the fiber without the silicone-based coating.

[0127] A sixth embodiment is any combination of the first five embodiments, wherein the filter media has an E3 filtration efficiency improvement of at least about 35% compared to the E3 filtration efficiency value of the fiber without the silicone-based coating.

[0128] A seventh embodiment is any combination of the first six embodiments, wherein the filter media has an E3 filtration efficiency improvement of at least about 40% compared to the E3 filtration efficiency value of the fiber without the silicone-based coating.

[0129] An eighth embodiment is any combination of the first seven embodiments, wherein the filter media has an E2 filtration efficiency increase of about 20% or more compared to the E2 filtration efficiency value of the fiber without the silicone-based coating.

[0130] 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.

[0131] A tenth embodiment is a combination of any of the first nine embodiments, wherein the silicone-based coating comprises at least about 5% silicone compound by weight of the coating.

[0132] An eleventh embodiment is a combination of any of the first ten embodiments, wherein the silicone compound is at least about 10% by weight of the coating.

[0133] A twelfth embodiment is any combination of the first eleven embodiments, wherein the silicone-based coating comprises a reactive silicone macroemulsion.

[0134] A thirteenth embodiment is a combination of any of the first twelve embodiments, wherein the silicone-based coating comprises an amino-functional polydimethylsiloxane.

[0135] A fourteenth embodiment is a combination of any of the first thirteen embodiments, wherein the silicone-based coating comprises polyethylene glycol monotridecyl ether.

[0136] A fifteenth embodiment is a combination of any of the first fourteen embodiments wherein the amino-functional polydimethylsiloxane comprises about 30 to about 40 weight percent of the coating.

[0137] A sixteenth embodiment is a combination of any of the first fifteen embodiments wherein the polyethylene glycol monotridecyl ether comprises about 5 to about 10 weight percent of the coating.

[0138] A seventeenth embodiment is any combination of the first sixteen embodiments, wherein the continuous fibers are spunbond fibers or meltblown fibers.

[0139] An eighteenth embodiment is a combination of any of the first seventeen embodiments, wherein the silicone-based coating further comprises an antistatic agent.

[0140] A nineteenth embodiment is any combination of the first eighteen embodiments, wherein the antistatic agent comprises a surfactant.

[0141] A twentieth embodiment is a combination of any of the first nineteen embodiments wherein the surfactant comprises a non-rewetting thermally decomposable surfactant / foaming agent.

[0142] A twenty-first embodiment is a combination of any of the first twenty embodiments, wherein the silicone-based coating is applied to the fiber by dipping the fiber into a container containing the silicone-based coating.

[0143] In a fifth aspect, an air filter product comprises the filter media of any combination of the first 21 embodiments.

[0144] In a sixth aspect, the first embodiment comprises providing a plurality of fibers and applying a silicone-based coating to the fibers, the silicone-based coating comprising at least about 2% by weight of the coating of a silicone compound.

[0145] A second embodiment is the first embodiment, wherein the silicone compound is at least about 5% by weight of the coating.

[0146] A third embodiment is a combination of any of the first two embodiments, wherein the silicone compound is at least about 10% by weight of the coating.

[0147] A fourth embodiment is a combination of any of the first three embodiments, wherein the weight add-on of the silicone-based coating is greater than about 1% based on the weight of the total fiber.

[0148] A fifth embodiment is any combination of the first four embodiments, wherein the weight add-on is greater than about 5% based on the total fiber weight.

[0149] A sixth embodiment is any combination of the first five embodiments, wherein the weight add-on is from about 6% to about 10% based on the total fiber weight.

[0150] A seventh embodiment is any combination of the first six embodiments, wherein the silicone-based coating is applied by a process selected from the group consisting of spraying the silicone-based coating onto the fiber, dipping the fiber into a container containing the silicone-based coating, and applying the silicone-based coating to the fiber as a foam.

[0151] An eighth embodiment is a combination of any of the first seven embodiments, further comprising forming the fibers by a process selected from the group consisting of spunbond and meltblown processes.

[0152] A ninth embodiment is any combination of the first eight embodiments, wherein a silicone-based coating is applied as a spin finish.

[0153] A tenth embodiment is any combination of the first nine embodiments, wherein a silicone-based coating is applied to the fibers prior to forming the filter media.

[0154] In a seventh aspect, an air filter is manufactured by the process of any combination of the first ten embodiments.

Claims

1. one or more fiber-containing layers; The filter media wherein the fibers are coated with a silicone-based coating comprising at least about 2% by weight of the coating of a silicone compound.

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

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

4. 10. The filter media of claim 1, wherein the silicone-based coating has an add-on weight of greater than about 1% based on the total weight of the fibers.

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

6. 5. 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. 10. The filter media of claim 1, wherein the fibers are staple fibers.

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

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

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

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

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

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

14. 13. The filter media of claim 12, wherein the polyethylene glycol monotridecyl ether comprises about 5 to about 10 weight percent of the coating.

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

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

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

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

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

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

21. a layer comprising continuous fibers having a spin finish of less than about 1%; a silicone-based coating on the fibers, wherein the weight add-on of the silicone-based coating is greater than about 1% based on the total weight of the fibers.

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

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

24. 22. 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. 22. The filter media of claim 21, wherein the filter media has an E3 filtration efficiency improvement of at least about 30% compared to the E3 filtration efficiency value of a fiber without the silicone-based coating.

26. 22. The filter media of claim 21, wherein the filter media has an E3 filtration efficiency improvement of about 35% or greater compared to the E3 filtration efficiency value of a fiber without the silicone-based coating.

27. 22. The filter media of claim 21, wherein the filter media has an E3 filtration efficiency improvement of about 40% or more compared to the E3 filtration efficiency value of a fiber without the silicone-based coating.

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

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

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

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

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

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

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

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

36. 35. The filter media of claim 34, wherein the polyethylene glycol monotridecyl ether comprises about 5 to about 10 weight percent of the coating.

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

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

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

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

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

42. 22. An air filter product comprising the filter media of claim 21.

43. providing a plurality of fibers; applying a silicone-based coating to the fibers, wherein the silicone-based coating comprises at least about 2% by weight of the coating of a silicone compound.

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

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

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

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

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

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

50. 44. The method of claim 43, further comprising forming the fibers in a process selected from the group consisting of spunbond and meltblown processes.

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

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

53. 44. An air filter made by the process of claim 43.

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