Air filter with ablative and sacrificial polymers

Abstract

A polymer comprising at least one pathogen inactivating component such that the pathogen inactivating component is released continuously over time by the ablation or sacrifice of the polymer. The polymer may be incorporated onto or into an air filter. The polymer may also be incorporated into the air filter in a gradient such that there is a higher concentration of the polymer and pathogen inactivating material or materials on the outer surface of the air filter and a lower concentration of the polymer and pathogen inactivating material or materials interior to the air filter matrix.

Description

[0001] Atty Dkt No.: IPAC-010WO AIR FILTER WITH ABLATIVE AND SACRIFICIAL POLYMERS CROSS-REFERENCE TO RELATED APPLICATIONS [1] This application claims the benefit of and priority to U.S. Provisional Patent Application No. 63 / 521,833 filed June 19, 2023, the entire disclosure of which is hereby incorporated by reference in its entirety for all purposes. BACKGROUND [2] Air filters for HVAC systems provide for the filtration of particles that are entrained in the impinging air. Depending upon the rating of the filter, smaller and smaller particles may be filtered out of the air. A specific type of filter, high efficiency particulate air (HEPA) filter, is utilized to filter micron and submicron particles from the air. [3] While very fine particle filters offer trapping of allergens and other problematic materials such as fine dust, all of these passive air filters do not allow for the inactivation of pathogens that may be borne by the air as it flows through the HVAC system. HEPA filters may also cause a high pressure drop across the filter, resulting in poor airflow through the HVAC system. [4] Thus, there is therefore a need for a long-lasting, pathogen inactivating, and high percentage capture air filter for HVAC systems. SUMMARY [5] The embodiment is the use of specialty polymers and pathogen inactivating materials where the specialty polymers are ablative or sacrificial. These specialty polymers incorporating pathogen inactivating materials may be utilized in air filters comprised of paper, woven fiberglass, nonwoven fiberglass, nonwoven polymers, electrospun polymer fibers and the like where the air filter or filters further comprise a method of inactivating pathogens through the use of a compound or compounds that are infused, coated or otherwise incorporated into or onto the air filters. [6] The air filter matrix is configured to have a loft or thickness in the Z direction of the filter. In one embodiment, the loft, lofted material, or thickness of the air filter is comprised of filaments or fibers that are either in a regular pattern, such as a weave, Page 1 of 25  Atty Dkt No.: IPAC-010WO or an entangled pattern, such as a nonwoven fabric. Filaments are typically comprised of a single strand of material while fibers are comprised of multiple strands of material. The air filter is configured such that air flows through the lofted air filter matrix, providing mechanical filtration of the incident air. The density of the air filter matrix will allow for the filtration of various particle sizes with a less dense air filter matrix filtering larger size particles and a more dense air filter matrix filtering larger and smaller size particles. This air filtration process provides for a mechanical filtration of the air. [7] The air filter matrix may also be configured to contain an ablative or sacrificial polymer and a pathogen inactivating material. With the incorporation of the ablative or sacrificial polymer and pathogen inactivating material, the air filter matrix is configured to also provide a biocidal filtration of the air where pathogens that impinge upon the air filter that is configured with an ablative or sacrificial polymer and a pathogen inactivating material are inactivated and rendered harmless for infection. [8] The embodiment is also a technique of applying the specialty ablative or sacrificial polymer and pathogen inactivating mixture or copolymerization in a manner configured to create a gradient of the specialty ablative or sacrificial polymer and pathogen inactivating materials from the exterior surface of the air filter matrix to the interior layers of the air filter matrix with the highest concentration of the ablative or sacrificial polymer and pathogen inactivating materials on the surface of the air filter matrix and lower concentrations of the ablative or sacrificial polymer and pathogen inactivating materials in the interior of the air filter matrix. [9] The embodiment is also the method of utilizing a finely atomized spray of the ablative or sacrificial polymer and pathogen inactivating material dispersed or dissolved in a solvent, such as water.

[0010] The air filter matrix may also be co-mingled with polymeric fibers or filaments that are ablative or sacrificial in nature and contain and / or are copolymerized with at least one pathogen inactivating material.

[0011] The air filter matrix may also be configured to contain both an ablative or sacrificial polymeric coating that is mixed with or copolymerized with at least one pathogen inactivating material and a co-mingled fiber or filament matrix where the co- mingled fiber or filament matrix is configured to be comprised of fibers or filaments of Page 2 of 25  Atty Dkt No.: IPAC-010WO an ablative or sacrificial polymer that is blended with and / or copolymerized with at least one pathogen inactivating material.

[0012] The embodiment is also a method of analysis to determine the depth of penetration into a fiber matrix of a specialized polymer and pathogen inactivating material mixture or copolymerization. A scanning electron microscope (SEM) equipped with an energy dispersive x-ray spectroscopy (EDS) system and detector is configured to analyze both the qualitative and quantitative amount of pathogen inactivating material or materials in different layers of the air filter matrix.

[0013] The polymer with ablative or sacrificial characteristics is configured to allow the surface of the polymer or the bulk of the polymer to wear down with time, exposing a new fresh surface of the polymer where the ablative polymer is concerned or a bulk breakdown of the polymer where a sacrificial polymer is concerned. This breakdown of the ablative or sacrificial polymer will expose fresh pathogen inactivating material to the environment.

[0014] The ablative or sacrificial polymer may be an emulsion polymer comprised of a polyvinyl acetate and acrylate backbone, mixed with a socialistic material, such as hydroxy ethyl cellulose, where the outer surface of the polymer will be worn away over time, exposing a new surface to the environment.

[0015] The biocide infused polymer may also be compounded such that, when coated onto the filter substrate, provides a continuous supply of the virucide or virucide to the air that is flowing through the filter. This process may also be known as bioactive filtration.

[0016] Yet another method of supplying a continuous amount of pathogen inactivating material is for the ablative or sacrificial polymer matrix to wear away over time while continuously exposing  to the environment the pathogen inactivating material or materials that have been infused into the polymer matrix.

[0017] The biocide or fungicide may be a blend of virucides or biocides or fungicides, each having a different target area of pathogens. As a result, multiple pathogens, such as Legionella, the pathogen causing Legionnaires’ disease, and SARS-CoV-2, the Page 3 of 25  Atty Dkt No.: IPAC-010WO virus causing the Covid-19 pandemic and Candida auris, may be inactivated at the same time.

[0018] The coating of the filter substrate may be accomplished by a spray, dip, roll, print, or other transfer process whereby an ablative or sacrificial polymer is transferred to the surface of the air filter. The air filter may be comprised of fiberglass filaments or fibers, polyolefin filaments or fibers, or a specialty paper. The ablative or sacrificial polymer may contain pathogen inactivating material such as a biocide or virucide. The roll process may be a Mayer rod process or a gravure process.

[0019] A fiberglass base material may be utilized for the HVAC filter. Here, the ablative or sacrificial polymer with a biocide or a virucide, or any other material that would inactivate a pathogen, is transferred to the fiberglass substrate. The fiberglass substrate may be woven or nonwoven. The ablative or sacrificial polymer will wear over time and exposed a new surface to the environment while it is coated on the fiberglass substrate.

[0020] The rating of the air filter may be of various levels. The American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) utilizes the standard as prescribed by ANSI / ASHRAE 52.2 for the Minimum Efficiency Reporting Value (MERV). A standard of MERV 13 or higher has been prescribed by the Center for Disease Control (CDC).

[0021] There are various biocides and virucides and fungicides available in the marketplace for the inactivation of pathogens, including the SARS-CoV-2 virus that is causing the Covid–19 pandemic. The biocides and virucides and fungicides include materials that incorporate chlorinated molecules such as quaternary ammonium salts with a chlorine molecule attached. Benzalkonium chloride is an example of the material with a quaternary ammonium component and a chlorine component. Many other types of biocides and virucides are available such as sodium hypochlorite (commonly known as bleach), hydrogen peroxide, and isopropyl alcohol. Other molecules include boron, iodine, and other chlorine containing molecules. Materials containing hydrogen peroxide or that generate hydrogen peroxide are also effective biocides, virucides, and fungicides. Page 4 of 25  Atty Dkt No.: IPAC-010WO

[0022] The polymers that are utilized in this embodiment have special characteristics for the changes of the polymers over time. Both ablative polymers and sacrificial polymers may be utilized for the coating material on the air filters. Ablative polymers tend to break down from the surface as a result of external forces such as the flow of a fluid, such as air, over the surface of the ablative polymer. Sacrificial polymers tend to break down in a bulk manner where the entire sacrificial polymer begins to break down from external forces such as the flow of the fluid over the surface of the sacrificial polymer. Various polymeric properties may be manipulated to produce either an ablative polymer or a sacrificial polymer and the breakdown of each respectively. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The foregoing aspects and other features of the disclosed embodiments are explained in the following description, taken in connection with the accompanying drawings, wherein:

[0024] Figure 1 illustrates an exemplary embodiment of an HVAC filter with a virucide infused coated fiberglass component.

[0025] Figure 2 is a chemical formula for benzalkonium chloride like materials with n = the alkyl component.

[0026] Figure 3 is a siphon feed spray gun with a fluid tip and a fluid atomizing air cap.

[0027] Figure 4 is chart of the particle sizes resulting from various spray equipment.

[0028] Figure 5 is a lofted or three-dimensional nonwoven fiberglass matrix with an ablative or sacrificial polymer combined with a pathogen inactivating material or materials on the outer surface.

[0029] Figure 6 is a SEM / EDS micrograph of a coated air filter matrix comprised of fiberglass filaments and an ablative or sacrificial polymer combined with a pathogen inactivating material where the different elements may be seen as different colors.

[0030] Figure 7 is a SEM micrograph of a coated air filter matrix comprised of fiberglass filaments and an ablative or sacrificial polymer combined with a pathogen inactivating material. Page 5 of 25  Atty Dkt No.: IPAC-010WO

[0031] Figure 8 is an SEM / EDS micrograph of an orthogonal cut through the lofted fiberglass matrix of an air filter coated with an ablative or sacrificial polymer containing a pathogen inactivating material containing chlorine.

[0032] Figure 9 is SEM / EDS spectrum of elements found in a fiber matrix containing an ablative or sacrificial polymer with a pathogen inactivating material.

[0033] Figure 10 is a diagram of the EDS process. DETAILED DESCRIPTION

[0034] The embodiments described herein disclose an air filter and a polymer where the polymer contains an agent, such as a pathogen inactivating material, for inactivating viruses, bacteria, and fungi. Specifically, the biocide in the polymer is used to inactivate the SARS–CoV–2 virus causing the Covid-19 pandemic. This process is known as bioactive filtration.

[0035] The polymer may be an ablative or sacrificial polymer that will wear away at the surface over time or degrade in a bulk manner, thus exposing new material to the environment. The polymer may also be a material that’s incompatible with the pathogen inactivating agent such that the pathogen inactivating agent, a biocide, will ooze out of the polymer for a long period of time and thus inactivate a pathogen, such as viral particles, when they impinge on an air filter.

[0036] An ablative or sacrificial polymer may also be known as a sacrificial material with the polymer subject to wear from environmental conditions. The ablation of a polymeric matrix may occur from thermal interaction, UV interaction, and other energetic, oxidating, or hydrogenating environmental interactions. The ablative or sacrificial polymer may also be comprised of nano composites. The sacrificial polymer may wear away and break down from environmental interactions.

[0037] The polymeric material, blended with a biocide, or any pathogen inactivating material, may be applied to the substrate by various means such as spraying, dipping, roll coating, and printing. Once the polymer is applied to the substrate, it may be cured or dried through various processes such as UV cure, drying in a heated oven, or air dried. Page 6 of 25  Atty Dkt No.: IPAC-010WO

[0038] In yet another process, filaments or fibers of an ablative or sacrificial polymer that are combined with a pathogen inactivating material or materials may be co- mingled with a secondary or tertiary polymer or other filaments or fibers such that the ablative or sacrificial pathogen inactivating polymer is part of a polymer or other filament or fiber filter matrix. Other filaments or fibers may be material such as fiberglass, cotton thread or similar materials. Other polymers, such as polyolefins, may be utilized to form the rest of the polymer filament for fiber filter matrix. This polymer fiber or filament filter matrix may also be subsequently coated with a secondary material to further enhance the filtration and pathogen inactivating capabilities.

[0039] The configuration of the multiple polymer filaments, in one embodiment, allows for electrostatic and pathogenic material interaction between the filaments, thus causing the spaces in the polymer fiber filter matrix to act in a pathogen inactivating manner as well. This process is akin to the use of mosquito repellent netting where the spaces in the netting, as well as the coated fibers in the netting structure itself, still acts to repel the malaria carrying mosquitoes and thus protect anyone inside of the netting structure.

[0040] Test procedures, such as ISO-18184:2019, may be utilized to demonstrate the anti-viral capacity of porous substrates. In accordance with ISO-18184:2019, samples of a non-woven fiberglass with a MERV rating of 13 treated with a polyvinyl acetate / acrylate copolymer infused with Stepan BTC-885, a benzalkonium chloride containing mixture, were tested. A material containing essentially 99.9% benzalkonium chloride was also tested. The pathogen that was tested utilizing the ISO-18184:2019 standard was the SARS-CoV-2 virus, WA1 strain. The results of the testing show that the polymer and virucide infused non-woven fiberglass MERV 13 filter inactivated all of the SARS-CoV-2 WA1 virus in 15 minutes. The test results are listed below in Table 1. Page 7 of 25  Atty Dkt No.: IPAC-010WO Table 1  Protocol #  ProjectTest Contact No.   Lot No.   Dilution  Virus  time  Log10 Reduction  Severe Acute Respirator Syndrome- IPAC.V.21.001  1123-Test N / Related 15 101   Material  A  CoronavirusMinutes  ≥ 3.39  2 (SARS- CoV-2) (COVID-19 Virus)

[0041] When a coating is used to apply the ablative or sacrificial polymer containing the pathogen inactivating material to an air filter, the substrate that the polymer is coated onto may be composed of various materials. The materials include both woven and nonwoven fiberglass, paper, nonwoven polymeric matrices, woven polymeric matrices, and similar support materials.

[0042] In one example, the spray equipment that is utilized to apply the ablative or sacrificial polymer containing a pathogen inactivating material is configured to form a very fine spray pattern with small droplet size so that the penetration of the spray into the air filter matrix produces a layered gradient in the air filter matrix of the ablative or sacrificial polymer containing the pathogen inactivating material. An example of the spray equipment is a Spectrum 32 ounce high transfer efficiency (HTE) compliant-air spray gun. The droplet size from this type of spray equipment is typically 300 to 4000 µm in diameter.

[0043] Spray equipment with piezoelectric or other specialty mechanical fluid atomizing configurations may also be utilized to spray the ablative or sacrificial polymer containing a pathogen inactivating material. This type of spray equipment may also be called an ultrasonic nebulizer. Here, the droplet size may range from 20 µm to 100 µm in diameter.

[0044] A lower than ambient pressure may be utilized on the backside of the filter, i.e. the side of the filter that is not being sprayed, so as to enhance the penetration of the Page 8 of 25  Atty Dkt No.: IPAC-010WO droplets from the atomized spray into the fiber and filament matrix of the air filter. This process may be accomplished by drawing air through the filter at a rate to improve the penetration of the sprayed droplets from the atomized ablative and / or sacrificial polymer and pathogen inactivating material, such as benzalkonium chloride.

[0045] The air filter may also be pretreated so as to change the surface tension on the fibers and filaments of the filter matrix to improve the flow of the ablative and / or sacrificial polymer containing the pathogen inactivating material when the polymer mixture or solution impinges on the fiber matrix as finely atomized droplets. The change in the surface tension will allow for differential flow of the polymer mixture or solution as the droplets from the atomized material contact the fibers and / or filaments of the air filter fiber and filament matrix.

[0046] The ablative and / or sacrificial polymer containing the pathogen inactivating material may also be added to the air filter matrix through the use of a powder coating. Here, the powder coatings are based on polymer resin systems and are combined with curatives, pigments, leveling agents, flow modifiers, antimicrobials, biocides, and other additives. These ingredients are melt mixed, cooled, and ground into a uniform powder that is 0.1 µm to 2000 µm in size. A process called electrostatic spray deposition (ESD) is typically used to achieve the application of the powder coating to a conductive substrate. This application method uses a spray gun, which applies an electrostatic charge to the powder particles, which are then attracted to the grounded part. Quaternary ammonium salts may be utilized as one method to charge nonconductive substrates and allow them to be grounded and received the electrostatically charged particles from the powder coating. The powder coating may then be cured using various methods such as heat, ultraviolet light, and free radical polymerization. The degree of cure may be modified so as to change the ablative and / or sacrificial nature of the polymer. The polymer backbone itself may also be modified so as to allow for faster ablation and / or sacrifice of the polymer and release of the antimicrobial, pathogen inactivating material such as benzalkonium chloride.

[0047] A second set of results show the data in table 2 where different levels of benzalkonium chloride were infused into the polyvinyl acetate / acrylate polymer. The parts by weight (pbw) of the benzalkonium chloride was incorporated at various levels. Page 9 of 25  Atty Dkt No.: IPAC-010WO The benzalkonium chloride in this test was a 99.5% material while the BTC – 885 material is 50% active with the other 50% being surfactant materials. Table 2   Number  Polymer IPAC‐08222022‐ 1  001  JM  None  IPAC‐08222022‐ 2  002  Polymer control  SC‐6125  IPAC‐08222022‐ 3  003  Polymer + 1.25 pbw BAC  SC‐6125  IPAC‐08222022‐ 4  004  Polymer + 2.5 pbw BAC  SC‐6125  IPAC‐08222022‐ 5  005  Polymer + 5.0 pbw BAC  SC‐6125  IPAC‐08222022‐ 6  006  Polymer + 10.0 pbw BAC  SC‐6125

[0048] Table 3 shows the results of the testing of the materials in table 2. Table 3

[0049] This test is designed to evaluate the virucidal effectiveness of the polymer matrix consisting of at least a base ablative or sacrificial polymer and a pathogen inactivating material infused into the polymer matrix against SARS-associated Coronavirus Type 2 (SARS-CoV-2). The test determined the potential of the pathogen Page 10 of 25  Atty Dkt No.: IPAC-010WO inactivating infused polymer matrix to inactivate the test virus via direct contact. The test is designed to simulate consumer use; and is based on the International Standard ISO 18184 method, "Textiles - Determination of Antiviral Activity of Textile Products".

[0050] The results show the complete inactivation of the SARS-CoV-2 virus at a 10 pbw level of the pathogen inactivating material and a complete inactivation to a 4.03 log reduction of the SARS-CoV-2 virus at a 5 pbw level of the pathogen inactivating material.

[0051] The depth of penetration of a sprayed amount of ablative or sacrificial polymer containing the pathogen inactivating material into an air filter matrix, as well as any motility of the ablative or sacrificial polymer and / or the pathogen inactivating material incorporated into the ablative or sacrificial polymer either as a mixture or as a copolymerization is of interest to form both a gradient on the surface of the air filter matrix and to track any motility of the pathogen inactivating material through the air filter matrix, both initially and over time.

[0052] The depth and amount of the gradient applied to an air filter matrix may be measured by a scanning electron microscope (SEM) equipped with an energy dispersive x-ray spectroscopy (EDS) system and detector where the SEM / EDS system is configured to show both the qualitative and quantitative characteristics of the applied ablative or sacrificial polymer combined with the pathogen inactivating material or materials.

[0053] The SEM / EDS technique may be utilized to identify most of the elements in the periodic chart through the characteristic x-ray emission of the elements

[0054] The polymeric coated substrate may then be fitted into a frame such that it may easily be inserted into an HVAC system that currently accepts regular types of filtration media.

[0055] Figure 1 is a depiction of an air filter 100. The cross members 101 of the air filter frame 102 retain the filtration substrate 103. The filtration substrate 103 may be a woven or non-woven substrate. The material of the filter substrate 103 may be paper, fiberglass, or another suitable material. The filtration substrate 103 may be coated with Page 11 of 25  Atty Dkt No.: IPAC-010WO a polymer where the polymer is infused with a virucide. The filtration substrate 103 may also be a co-mingled fiber matt that forms of polymer filter fiber matrix comprised of ablative polymer filaments that are woven with other polymer filaments such as polyolefins or polyurethanes.

[0056] The molecule is shown in Figure 2 is a depiction of the benzalkonium chloride molecule with the alkyl group defined by “n” which is typically equal to 8, 10, 12, 14, 16, and 18. This material is also known as a quaternary ammonium salt.

[0057] The spray gun that is shown in Figure 3 is a siphon type spray gun with a fluid tip and a fluid atomizing air cap. Various models of spray guns may be utilized to apply the ablative or sacrificial polymer and pathogen inactivating material. In this particular depiction, the fluid to be sprayed is siphoned from the paint cup into a fluid nozzle when the trigger of the gun is activated, allowing pressurized air to flow through the spray gun and siphon fluid into the fluid tip. This fluid is then atomized into fine droplets utilizing an air cap that impinges compressed air onto the fluid stream, causing the fluid stream to break into the fine droplets. The fluid nozzle and the air cap combination may be modified to deliver more or less fluid through the fluid nozzle and more or less compressed air, in different patterns, through the air cap. When the trigger of the spray gun is pulled, a needle that is blocking the fluid nozzle is pulled back, allowing fluid to flow through the fluid nozzle from the paint cup by a siphon action.

[0058] The chart that shown in Figure 4 lists various droplet diameters for different particle sizes. A course spray pattern may be greater than 400 µm in diameter for the droplets while a fine aerosol pattern may be less than 25 µm for the droplets diameter.

[0059] The material depicted in Figure 5 is an orthogonal view 500 of a fiberglass matrix 501 with a coating 502 on the top surface comprised of an ablative or sacrificial polymer containing a pathogen inactivating material.

[0060] The material that is shown in Figure 6 is also an orthogonal view 600 of a fiberglass matrix 601 with a coating 602. The image in Figure 6 is generated through the use of the SEM / EDS analytical technique. The different shades or colors in the image are indicative of assigned values, by the SEM / EDS software, for different elements. The colors are subjective and are at the discretion of the SEM / EDS operator. The assignments for the elements 603 may be seen in the lower left corner Page 12 of 25  Atty Dkt No.: IPAC-010WO of Figure 6. Chlorine, carbon, silicon, sodium, and oxygen are all imaged. The coating on the top surface 601 of the fiberglass matrix 602 shows combinations of carbon and chlorine which is indicative of the ablative or sacrificial polymer (associated carbon atoms) and the pathogen inactivating material (associated chlorine atoms).

[0061] A fiberglass matrix that has been sprayed with a ablative or sacrificial polymer complied with a pathogen inactivating material is depicted in Figure 7. The SEM micrograph 700 shows sprayed particles 701 that are adhered to the fiberglass fibrils 702 on the surface of the fiberglass matrix 703. The SEM micrograph 700 indicates a gradient from left to right with the left side of the SEM micrograph showing coating of the fiberglass fibrils 701 while the right side of the SEM micrograph shows no coating penetrating into the fiberglass matrix 703 beyond a certain distance. The left side of the SEM micrograph is the top of the air filter matrix while the right side is a depth of the air filter matrix below or distal from the top or proximal layer of the air filter matrix.

[0062] A gradient is also shown in Figure 8 where a SEM / EDS image 800 of a coated fiberglass matrix is shown. Here, chlorine, silicon, oxygen, and carbon are analyzed using the SEM / EDS analytical process. The different shaded areas or color differences indicate the different elements in the different locations of the SEM / EDS micrographs. A carbon containing area 801 is different from a carbon and chlorine containing area 802. These areas are both different from a silicon oxide area 803. The carbon and carbon / chlorine areas are the ablative or sacrificial polymer (indicated by carbon atoms) containing the pathogen inactivating material (indicated by the chlorine atoms). This differential and shading or color shows the gradient from the left side of the SEM / EDS micrographs to the right side of the SEM / EDS micrographs where there is the ablative or sacrificial polymer along with the pathogen inactivating material on the left side, the top or proximal layer of the fiberglass matrix (carbon and chlorine atoms), and only the fiberglass matrix (and oxygen atoms) on the right side, distal from the top or proximal layer, of the SEM / EDS micrograph. The left side of the SEM / EDS micrograph is the top of the fiberglass matrix depicted in Figure 6 while the right side of the SEM / EDS micrograph is the middle part of the polymer matrix 602, distal from the top layer, in Figure 6.

[0063] The graph 900 shown in Figure 9 indicates the abundance of the various elements in the SEM / EDS scan of the fiberglass matrix that is coated with an ablative Page 13 of 25  Atty Dkt No.: IPAC-010WO or sacrificial polymer containing a pathogen inactivating material. Here, the higher abundance of oxygen 901 and silicon 903 are indicative of the fiberglass filaments while the carbon atoms 802 and chlorine atoms 904 are indicative of the ablative or sacrificial polymer (carbon) containing the pathogen inactivating material (chlorine). The chlorine atom 905 is also indicated on the graph along with other elements. The platinum and palladium atoms that are shown in the analysis are due to the metal coating that was sputter coated onto the surface of the coated fiberglass matrix. The platinum and palladium coating is utilized to improve the fidelity of the SEM / EDS analysis and the clarity of the SEM micrograph.

[0064] Figure 10 is a depiction of the process of energy dispersive x-ray spectroscopy. The emission of characteristic x-rays of various elements in a specimen are stimulated by a beam of electrons focused on a specimen. The beam of electrons dislodges an inner shell orbital electron from an atom which is replaced by an outer shell electron to stabilize the atom. During this process, the outer shell electron, which is higher in energy than the inner shell electron, emits energy in the form of x-rays when it returns to ground state which are characteristic of the element and have a specific energy value for each element. Thus, the presence of the elements and a qualitative analysis may be accomplished. The intensity of the characteristic x-rays of the element may also be used to determine the amount of each element (quantitative analysis) as well as the location of the elements, also known as x-ray mapping. For instance, if the initial vacancy occurs in the K shell and the vacancy filling electron drops from the adjacent (L) shell, a Kαx-ray is emitted. If the electron drops from the M shell (two shells away), the emitted x-ray is a Kβ x-ray. Similarly, if an L-shell electron is ejected and an electron from the M-shell fills the vacancy, Lαradiation will be emitted. As an example, a chlorine atom has a principle line keV of Kα = 2.6219.

[0065] The air filter embodiment, in one example, is configured to contain multiple biocides so as to inactivate multiple pathogens that pass through or are collected by the air filter. It is important to understand the efficacy of each of the biocides over time as well as the motility of the biocides and any biocide degradation products. In this case, the SEM / EDS technique may be utilized to not only determine the initial location of the various biocides in the air filter but also the motility of the biocides and biocide degradation products over time. Page 14 of 25  Atty Dkt No.: IPAC-010WO

[0066] The recent spread of Candida auris points out the need for fungicidal as well as biocidal activity in air filtration. In several studies, it was shown that hydrogen peroxide, H2O2, is highly effective at the destruction of C. auris infections. It is somewhat impractical to include hydrogen peroxide as a liquid in air filters without any protection of the hydrogen peroxide from natural break down into water and oxygen gas. However, compounds such as calcium peroxide, CaO2, and sodium percarbonate, Na2H3CO6, will decompose to release hydrogen peroxide under certain environmental conditions. Typically, calcium peroxide requires an acidic condition to release hydrogen peroxide while sodium percarbonate will decompose into hydrogen peroxide and sodium carbonate when exposed to or dissolved in water. Thus, even when exposed to moderate humidity, sodium percarbonate will release hydrogen peroxide into the air filter matrix.

[0067] Through the incorporation of materials such as calcium peroxide and sodium percarbonate into an ablative or sacrificial polymer, the resultant hydrogen peroxide decomposition material from the material such as calcium peroxide and sodium percarbonate may occur over time depending upon the ablation or sacrifice of the polymer matrix surrounding the calcium peroxide or sodium percarbonate. Thus, a slow breakdown of the ablative or sacrificial polymer will allow for a continued exposure of hydrogen peroxide to the environment of the air filter over time. Secondary agents, such as peracetic acid, CH3CO3H, may be utilized to activate materials such as calcium peroxide to release hydrogen peroxide. The secondary agents may be utilized as an admixture with an ablative or sacrificial polymer where the secondary agents and ablative or sacrificial polymers are separate from the hydrogen peroxide producing material, such as calcium peroxide. As such there may be a primary ablative or sacrificial polymer and a secondary ablative or sacrificial polymer where one ablative or sacrificial polymer with a secondary agent may be utilized in the same matrix as an ablative or sacrificial polymer with the hydrogen peroxide producing material, thus keeping the secondary agent and the hydrogen peroxide producing material separate until the primary and secondary ablative or sacrificial polymer begins to break down and cause the release of hydrogen peroxide.

[0068] In one aspect of the ablative or sacrificial polymer matrix with the pathogen inactivating material, an indicator dye or colorants may be configured to indicate the Page 15 of 25  Atty Dkt No.: IPAC-010WO coverage of the sprayed material onto a substrate or the color of co-mingled fibers of the polymer matrix with the pathogen inactivating material in a filamentous substrate. An indicator dye or colorants may be utilized also to indicate the lifespan of the filter system and when a replacement is necessary. For instance, a blue dye may be added to the polymer matrix and pathogen inactivating solution such that, after the solution is sprayed and dried onto a substrate, the die will fade over time, such as 30 days, the indicate the need for the replacement of the air filter.

[0069] While various aspects and embodiments have been disclosed herein, other aspects and embodiments will be apparent to those skilled in the art. The various aspects and embodiments disclosed herein are for purposes of illustration and are not intended to be limiting, with the true scope and spirit being indicated by the following claims. Page 16 of 25

Claims

Atty Dkt No.: IPAC-010WO What is claimed is:

1. An air filter comprising: a filter matrix comprised of filaments or fibers where the filaments or fibers form a three-dimensional structure with an upper surface and an inner filament or fiber matrix and; where the upper surface of the three-dimensional structure of the filter matrix is comprised of an ablative or sacrificial polymer combined with at least one pathogen inactivating material and; where the ablative or sacrificial polymer combined with the at least one pathogen inactivating material forms a gradient from high concentration on the upper surface of the three-dimensional structure of the filter matrix to a lower concentration of the ablative or sacrificial polymer combined with the at least one pathogen inactivating material further into the inner fiber matrix of the three-dimensional structure of fibers.

2. The filament or fiber matrix of claim 1 where elemental analysis indicates the depth and composition of the gradient of the ablative or sacrificial polymer combined with the at least one pathogen inactivating material.

3. The elemental analysis of claim 2 where the elemental analysis is a result of a scanning electron microscope equipped with an energy dispersive x- ray spectroscopy system.

4. The at least one pathogen inactivating material in claim 2 where the at least one pathogen inactivating material has a Kα of > 2.

0.

5. The at least one pathogen inactivating material of claim 1 where the at least one pathogen inactivating material is benzalkonium chloride.

6. The benzalkonium chloride of claim 5 where the alkyl group is greater than or equal to 8 and less than or equal to 18.

7. The at least one pathogen inactivating material of claim 1 where the at least one pathogen inactivating material is sodium percarbonate.

8. The at least one pathogen inactivating material of claim 1 where the at least one pathogen inactivating material is calcium peroxide.

9. The at least one pathogen inactivating material of claim 1 where the at least one pathogen inactivating material is hydrogen peroxide. Page 17 of 25 Atty Dkt No.: IPAC-010WO 10. The filter matrix of claim 1 where the filter matrix is pretreated before the addition of the ablative or sacrificial polymer with at least one pathogen inactivating material.

11. An air filter comprising: a filter matrix comprised of filaments or fibers where the filaments or fibers form a three-dimensional structure with an upper surface and an inner filament or fiber matrix and; where the upper surface of the three-dimensional structure of the filter matrix is comprised of an ablative or sacrificial polymer combined with at least one pathogen inactivating material and; where the ablative or sacrificial polymer combined with the at least one pathogen inactivating material forms a gradient from high concentration on the upper surface of the three-dimensional structure of the filter matrix to a lower concentration of the ablative or sacrificial polymer combined with the at least one pathogen inactivating material further into the inner fiber matrix of the three-dimensional structure of fibers and; where the filter matrix of filaments or fibers is co-mingled with polymeric fibers containing at least one pathogen inactivating material and; where the co-mingled polymeric fibers are ablative or sacrificial.

12. The at least one pathogen inactivating material in claim 10 where the at least one pathogen inactivating material has a Kα of > 2.

0.

13. The at least one pathogen inactivating material of claim 10 where the at least one pathogen inactivating material is benzalkonium chloride.

14. The benzalkonium chloride of claim 12 where the alkyl group is greater than or equal to 8 and less than or equal to 18.

15. The at least one pathogen inactivating material of claim 10 where the at least one pathogen inactivating material is sodium percarbonate.

16. The at least one pathogen inactivating material of claim 10 where the at least one pathogen inactivating material is calcium peroxide.

17. The at least one pathogen inactivating material of claim 10 where the at least one pathogen inactivating material is hydrogen peroxide.

18. The filter matrix of claim 11 where the filter matrix is pretreated before the addition of the ablative or sacrificial polymer with at least one pathogen inactivating material. Page 18 of 25 Atty Dkt No.: IPAC-010WO 19. A method of modifying an air filter comprising: impinging a filter matrix comprised of filaments or fibers with an ablative or sacrificial polymer containing at least one pathogen inactivating material and; where the droplet or particle diameter of the impinging spray is less than or equal to 500 microns.

20. The method of claim 11 where the droplet or particle diameter is less than 25 microns.

21. The method of claim 17 where the impinging spray is applied via piezoelectric spray device.

22. The method of claim 17 where the impinging spray is applied via a siphon spray device. Page 19 of 25

Images