Filter medium for filtration devices, and method for manufacturing and using the same.

Abstract

A filter medium is presented comprising a first layer containing a first plurality of fibers. The first plurality of fibers are characterized by an average diameter of approximately 50 microns or less, a thickness of approximately 1.7 mm or more, and a base weight of approximately 90 gsm or more. The first layer has an initial NaCl efficiency of approximately 75% or less at a face velocity of 14 cm / s. The filter medium also comprises a second layer containing a second plurality of fibers, the second plurality of fibers being characterized by an average diameter of 8 microns or more. The second layer has an initial NaCl efficiency of approximately 75% or more at a face velocity of 14 cm / s.

Description

[Technical Field]

[0001] An improved gradient filter medium for filtration applications and a method for manufacturing the same are described. The filter medium has a high loading capacity, low pressure loss, and high efficiency for particle filtration. [Overview of the project]

[0002] It is desirable to identify filter media with improved loading and / or reduced pressure loss. Such filter media may be useful in a variety of applications, including respiratory protection devices, furnace filters, heating, ventilation and air conditioning (HVAC) filters, air conditioning filters, and / or portable air purifiers or fans.

[0003] A filter medium is presented comprising a first layer containing a first plurality of fibers. The first plurality of fibers are characterized by an average diameter of approximately 50 microns or less, a thickness of approximately 1.7 mm or more, and a base weight of approximately 90 gsm or more. The first layer has an initial NaCl efficiency of approximately 75% or less at a face velocity of 14 cm / s. The filter medium also comprises a second layer containing a second plurality of fibers, the second plurality of fibers being characterized by an average diameter of 8 microns or more. The second layer has an initial NaCl efficiency of approximately 75% or more at a face velocity of 14 cm / s.

[0004] The above summary is not intended to describe each embodiment. Details of one or more embodiments of the invention are also described below. Other features, purposes, and advantages are evident from the description and claims. [Brief explanation of the drawing]

[0005] [Figure 1A] Figure 1A shows a respiratory protection device that can benefit from the embodiments described herein. [Figure 1B] Figure 1B shows a respiratory protection device that can benefit from the embodiments described herein. [Figure 1C] Figures 1C-1 to 1C-6 show a respiratory protection device that can benefit from the embodiments of this specification.

[0006] [Figure 2] Figure 2 is a schematic view showing a shirred filter medium that can be used in the embodiments of this specification.

[0007] [Figure 3] Figure 3 is a schematic view showing a cross-section of a shirred filter medium and its structure.

[0008] [Figure 4] Figure 4 is a schematic view showing the manufacture of a shirred filter medium according to an embodiment of the present disclosure.

[0009] [Figure 5] Figures 5A to 5B are schematic views showing cutaway views of a filter for a respiratory protection device according to an embodiment of this specification.

[0010] [Figure 6A] Figures 6A-1 to 6A-2 show some exemplary embodiments of the present invention. [Figure 6B] Figures 6B-1 to 6B-2 show some exemplary embodiments of the present invention.

[0011] [Figure 7] Figure 7 shows a method for manufacturing a filter for a respiratory protection device according to some embodiments of this specification.

[0012] [Figure 8] Figures 8A to 8D show a filter cartridge according to some embodiments of this specification.

[0013] [Figure 9] Figure 9 shows an indoor air purification device according to some embodiments of this specification.

[0014] [Figure 10A] Figure 10A shows different furnace filter configurations according to some embodiments of the present specification. [Figure 10B] Figure 10B shows different furnace filter configurations according to some embodiments of the present specification. [Figure 10C] Figure 10C shows different furnace filter configurations according to some embodiments of the present specification. [Figure 10D] Figure 10D shows different furnace filter configurations according to some embodiments of the present specification.

[0015] [Figure 11] Figures 11A to 11B show cross-sectional views of filters according to some embodiments of the present specification.

Mode for Carrying Out the Invention

[0016] The terms used in this specification are as follows. "A", "an", and "the" are used interchangeably and mean one or more. Also, "and / or" is used to indicate that one or both states can occur. For example, A and / or B includes (A and B) and (A or B).

[0017] Also, in this specification, when a range is described with endpoints, it includes all numerical values within that range (e.g., 1 to 10 includes 1.4, 1.9, 2.33, 5.75, 9.98, etc.).

[0018] Also, in this specification, the description "at least one" includes all numbers greater than or equal to 1 (e.g., at least 2, at least 4, at least 6, at least 8, at least 10, at least 25, at least 50, at least 100, etc.).

[0019] As used herein, "containing at least one of A, B, and C" refers to element A alone, element B alone, element C alone, A and B, A and C, B and C, and any combination of all three.

[0020] Figures 1A–1C illustrate respiratory protection devices that can benefit from embodiments of this specification. As used herein, “respiratory protection devices” may include disposable devices (e.g., single-use disposable respirators (e.g., DRs)), reusable respirators (e.g., respirators (RRs) having a half- or full-face elastomer facepiece and / or a replaceable filter), hybrid DR-RR products (e.g., particulate matter respirators available from 3M, model numbers 8825+ or 8835+), and powered air purifying respirators (e.g., PAPRs), pre-filters or other components of the respirator, or other devices including the respirator. However, it is expressly considered that the filter media described herein may be used in all of the above types of respiratory protection devices. Furthermore, while respiratory devices are described herein as examples of useful embodiments, it is expressly considered that the filter media described herein may also be useful in other filter applications, including furnace filters, air conditioning filters, indoor air purifiers, or other suitable applications.

[0021] Depth-loading filters can typically be used in reusable respirators consisting of permanent or replaceable cartridges or elastomer facepieces with filters. These can be used for respiratory protection from particulate matter and gases and vapors. Filters for protection from particulate environments may be simple particle filters or particle filters placed before gas and vapor cartridges (if protection from gases and vapors is also desired). For these applications, products range from flat, pancake-style filters like the 3M® 2091 filter (currently available from 3M) to pleated packs such as the 3M® 7093 or 3M® 60926 filters (both available from 3M). Furthermore, in some applications such as spray painting, a prefilter can be added to the gas filter to provide replaceable particle filtration for the 6001 cartridge for gas and vapor only, for example, by placing a 3M® 5N11 in front of the 3M® 6001 filter using a 3M® 501 retainer (all available from 3M). Deep loading filters may be used in any of these applications, or in other suitable applications or respirator models, to increase loading capability, reduce pressure loss (i.e., breathing resistance) at a given load, and / or to simplify the filter structure.

[0022] Figure 1A shows PAPR10 being worn by user 14. PAPR10 includes a breathing headgear 16 positioned on user 14's face, which forms a breathing space 18 into which filtered air is supplied via a breathing tube 20 for the user to inhale and for the user to exhale. The breathing headgear 16 may be a breathing mask, hood, helmet, hard head top, or other suitable component having an inlet for filtered air and defining the breathing space 18 for the user. PAPR10 includes a blower / filter unit 22, which is typically attached to user 14 via a belt 26 secured to user 14's waist. The blower / filter unit 22 is designed to be worn by the user in an atmosphere containing undesirable respiratory (and potentially other) contaminants.

[0023] The blower / filter unit 22 contains a replaceable filter housing 50 which includes a filter medium 60. The filter medium 60 is designed to remove particulate matter, chemical gases, and / or vapors by filtration as air passes through it (e.g., using a blower). The filter medium 60 needs to be replaced periodically because its filter capacity is not unlimited.

[0024] Filters are desired that offer greater capacity and lower pressure loss for longer service life and / or user comfort, while also being highly efficient to meet regulatory standards.

[0025] One of the most common ways to balance these design aspects is to increase the surface area of ​​the filter medium in a pleated form. Figures 1C-1 to 1C-5 show pleated media packs in different examples used in respirators, and Figure 1C-6 shows a flush sheet filter for PAPR. Pleated media packs offer better filtration performance than flat media, but result in a thicker and bulkier configuration, occupying more space within the filter device for PAPR. Since the blower / filter 22 must be installed by the PAPR user, there are limits to the practically acceptable bulk and weight. Furthermore, pleated media require sealing the pleated pack to the filter frame, which presents a manufacturing challenge. In addition, pleated packs are difficult to conform to curved or irregular shapes, requiring a box-like and / or bulky design. Figures 1C-1 and 1C-6 are provided for illustrative purposes only, and it is explicitly considered that the filter media described herein may also be useful for other applications used in cartridges.

[0026] Another common method is to reduce pressure loss by increasing the surface area of ​​the flat-form medium. For example, 3M's Airstream electric air purifying respirator (PAPR) uses a large bag filter, as shown in Figure 1C-6. In a flat-form PAPR filter, the total surface area of ​​the medium is 600 cm². 2 More than 700cm 2 It is common for them to be larger or larger than this. Large, flat media are typically configured into curved or irregular shapes to obtain a better shape factor within the filter device, requiring clearance around them so that the entire surface area of ​​the media is exposed to the airflow and used. This leads to a bulky design. Furthermore, large, flat sheets lack the mechanical strength to stand on their own, so they are more likely to require a support structure, which also contributes to a "bulky" filter.

[0027] Therefore, there is a need for a high-performance particle deep loading medium that offers filtration performance equivalent to pleated packs and conventional large media, while having a more compact footprint.

[0028] It is desirable to improve filters to improve particle loading capacity and pressure drop with acceptable filtration efficiency while maintaining ease of use. Embodiments of this specification relate to high-performance particle deep loading filtration media. The filters in the embodiments of this specification are multilayer composite materials having at least two layers of different filter media, as described below. The filter media of the different layers may differ from each other in several different parameters. For example, the first layer may be composed of a different material from the second layer. Separately or additionally, the first layer may have different fiber sizes and / or base weights and / or solidities. Separately or additionally, the first layer may be of different types of nonwoven materials (e.g., spunbond vs. meltblown). Separately or additionally, the first layer may be composed of the same material but have a greater surface area per unit area (e.g., square inch or square centimeter) of the filter. The first and second layers may differ in other ways as well. Furthermore, in some embodiments, there is a third layer of filter media that differs from both the first and second layers with respect to any of the parameters described above.

[0029] The multilayer composite filters described in the embodiments herein enable high particle loading capacity, high filtration efficiency, and low pressure drop. High particle loading capacity, high filtration efficiency, and low pressure drop are highly desirable, but are difficult to achieve with conventional filter media due to the competing nature of these performance attributes. For example, while adding an additional layer of filter media can increase loading capacity, it generally increases pressure drop.

[0030] Each layer in the filter described herein can function as a different functional zone within the filter as a whole. For example, the upstream or inlet layer (e.g., the first layer encountered by the air passing through the filter) may consist of a single layer of a medium primarily designed for high particle loading. The inner layer may consist of a single medium primarily designed for high efficiency (e.g., capturing a high percentage of all particles passing through it). In some embodiments, there may be one or more transition layers designed for a combination of high loading capacity and high efficiency.

[0031] In embodiments of this specification, a pleated medium may be used in one or more layers of a composite filter. Figures 2–4 illustrate and describe a method for manufacturing a pleated filter medium. Additional details regarding the structure of the pleated medium are described in U.S. Provisional Patent Application 63 / 434365, filed December 21, 2022. The terms “pleated medium” and “wrinkled medium” are used herein to refer to a medium that has been wrinkled, as described, for example, in relation to Figures 3–4. However, it is expressly considered that wrinkled or pleated mediums may be manufactured by other suitable methods.

[0032] Figure 2 shows an example of a pleated or wrinkled filter medium of the present disclosure. The wrinkled filter medium 100 includes several spaced elastic filaments. The elastic filaments are sandwiched between two nonwoven porous fiber webs coated with adhesive. During the manufacture of the pleated filter medium (referred to here as the “medium”), the elastic filaments are stretched under tension, and when the tension is released, the nonwoven porous fiber webs become wrinkled. Figure 2 shows a side view of a first nonwoven porous fiber web 124 and a second nonwoven porous fiber web 126, with the elastic filaments 122 positioned between them. Figure 2 shows the first nonwoven porous fiber web 124 in direct contact with the second nonwoven porous fiber web 126. Images of actual wrinkled articles manufactured in accordance with this disclosure are shown in Figures 4–6 and 7A and 7B of U.S. Provisional Patent Application 63 / 434365, filed December 21, 2022. From the resulting articles, it is conceivable that, when an adhesive is used, the adhesive would bond the two nonwoven porous fiber webs to the filaments between them. The bonding of the first and second nonwoven porous fiber webs is discontinuous, and it is inferred that the nonwoven porous fiber webs may not be bonded to the filaments (e.g., by the adhesive) over the length of the filaments.

[0033] According to some embodiments of this specification, one or more nonwoven porous fiber webs are formed of fibers having discrete lengths. <Materials List - Adhesive, Elastic Filament, Test Aerosol> [Table 1] <Material list - Non-woven media> [Table 2] <Elastic filament>

[0034] The filaments of this application include polymers and are inherently elastic—meaning that the filaments can recover or at least partially recover their length after stretching. Examples of polymer materials that may be used in the filaments of this application include natural rubber, polyether-polyurethane, polyamide, polyisoprene, copolymers of isoprene and neoprene, polymers of 2-chloro-1,3-butadiene, polyether-polyurea copolymers (e.g., Lycra), and polyurethane (e.g., spandex).

[0035] In one embodiment, the average diameter of the filament is at least 1, 5, 10, or 20 micrometers, and at most 25, 50, 100, 200, 400, 600, 800, 1000, or 1200 micrometers. In one embodiment, the denier of the filament is at least 100, 150, 175, 200, 210, 220, 250, or 500. In one embodiment, the denier of the filament is at most 1200, 900, 800, 700, 600, 500, 400, 350, 300, 250, or 225 denier. <Nonwoven porous fiber web>

[0036] Multiple elastic filaments are arranged between two nonwoven porous fiber webs—referred to here as nonwoven webs. The nonwoven webs of this disclosure can be manufactured by wet molding, carding, airlaid, spunlace, spunbond, spunmelt, or melt-blown techniques, or a combination thereof. The nonwoven webs herein can also be formed from fibrillated films (USRE 32171 - Method for manufacturing electret fiber filters). In some embodiments, the nonwoven webs may undergo a relofting process after formation to increase their loftiness. The nonwoven webs may include or consist of scrim or net. The nonwoven webs may contain nanofibers produced by an electrospinning process or other suitable process. Spunbond fibers are formed by extruding a molten thermoplastic polymer as filaments from multiple fine, usually circular, capillaries of a spinneret, the diameter of the extruded fibers rapidly decreasing. Meltblown fibers are formed by extruding molten thermoplastic material as molten threads or filaments through multiple fine, usually circular or square die-capillaries into a high-speed, usually heated gas (e.g., air) stream—which thins the filaments of the molten thermoplastic material. The meltblown fibers are then carried by the high-speed gas stream and deposited on a collection surface as a web of randomly dispersed meltblown fibers. Any nonwoven web can be made from a single type of fiber or from two or more types of different thermoplastic polymers and / or fibers of different thicknesses.

[0037] Re-expanded spunbond or ultra-high loft (UHL) filter nonwoven materials were prepared as follows. Bulkiness can be described in terms of solidity. "Solidity" is a property of the nonwoven web that is inversely correlated with density and indicates the permeability and porosity of the web (low solidity corresponds to high permeability and high porosity), and is defined by the following Equation 1.

number

[0038] Some embodiments of this specification have a solidity of less than 12%. Some embodiments have a solidity of less than 10%. Some embodiments have a solidity of less than 8%. Some embodiments have a solidity of less than 6%. Some embodiments have a solidity of less than 4%.

[0039] Continuously extruded melt-spun fibers were manufactured and collected in general accordance with the procedure described in the examples of U.S. Patent No. 8,240,484. The collected fibers were spontaneously bonded to form a self-supporting spunbond web in general accordance with the procedure described in U.S. Patent No. 9,976,771 (incorporated herein by reference) and area-bonded using the general method of calendering described in the '484 patent. Area bonding of the web was estimated to be present in about 1.5–1.6% of the web area. The web was hydrocharged in general accordance with the procedure disclosed in U.S. Patent No. 8,790,449 (incorporated herein by reference). Samples of the flat web were approximately 55 grams per square meter (g / m²). 2 The base weight of ) was shown.

[0040] Flat web samples were then re-inflated by needle punching. The needles were arranged in 32 rows (in a top-side punching configuration including upper and lower hole boards spaced approximately 50 mm vertically apart), with each row extending over a width of 85 cm (cross web), and the rows spaced 28.5 cm apart along the down web direction. Each row contained 104 needles (the needle spacing within the row was approximately 8 mm). The needles were of a common type available under trade name 609831 15X18X25X3 1 / 2 R333 G 3007, supplied by GROZ-BECKERT GmbH in Albstadt, Germany. The webs were passed through the needle puncher continuously at a speed of approximately 10 meters per minute. As the webs passed through the needle punching unit, they were needle-punched at a speed of approximately 350 strokes per minute. Based on these parameters, it was estimated that the web was punched at a density of approximately 25 punches per square centimeter of web material. Punching was performed from only one side (the top side).

[0041] The increase in web bulk was clearly visible even with a simple visual inspection. That is, the re-inflated web was noticeably thicker and "fluffier" than the web in its initial state, and most of the surface-bonded areas were not visible, but rather appeared to be covered by overlapping fibers. The re-inflated web exhibited a very uniform appearance, with an effective fiber diameter (EFD) of 28 μm and a solidity of 3.9%. Suitable thermoplastic polymer materials include, but are not limited to, polyolefins (e.g., polypropylene or polyethylene), poly(isoprene), poly(butadiene), fluorinated polymers, chlorinated polymers, polyamides, polyimides, polyethers, poly(ethersulfone), poly(sulfone), poly(vinyl acetate), polyesters (e.g., poly(lactic acid)), copolymers of vinyl acetate (e.g., poly(ethylene)-co-poly(vinyl alcohol)), poly(phosphazene), poly(vinyl ester), poly(vinyl ether), poly(vinyl alcohol), and poly(carbonate).

[0042] Suitable polyolefins include, but are not limited to, poly(ethylene), poly(propylene), poly(1-butene), poly-4-methyl-1-butene, copolymers of ethylene and propylene, α-olefin copolymers (e.g., copolymers of ethylene or propylene with 1-butene, 1-hexene, 1-octene, 1-decene), poly(ethylene-co-1-butene), poly(4-methyl-1-pentene), and poly(ethylene-co-1-butene-co-1-hexene).

[0043] Suitable polyamides include, but are not limited to, typical nylon polymers such as poly(iminoadipoyliminohexamethylene), poly(iminoadipoyliminodecamethylene), and polycaprolactam. Suitable polyimides include, but are not limited to, poly(pyromellithimide).

[0044] Suitable poly(ethersulfones) include, but are not limited to, poly(diphenyl ethersulfone) and poly(diphenylsulfone-co-diphenylene oxidesulfone).

[0045] Suitable vinyl acetate copolymers include, but are not limited to, poly(ethylene-co-vinyl acetate) and copolymers in which at least some of the acetate groups are hydrolyzed to provide a variety of poly(vinyl alcohols).

[0046] The fiber selected for a nonwoven web depends on the type of particles being filtered. Particularly useful fibers include meltblown fiber webs, for example, disclosed in Wente, Van A.'s "Superfine Thermoplastic Fibers" (48 Industrial Engineering Chemistry, 1342 et seq, 1956). Meltblown fiber webs provide a particularly excellent filtration layer when used in a persistently charged form (see U.S. Patent No. 4,215,682, Kubik et al.). Preferably, these meltblown fibers are microfibers having an effective diameter of at least 4, 6, 8, or 10 micrometers, and up to 12, 14, 16, or 20 micrometers. Other particularly useful filtration fibers are charged fibrillated film fibers, such as those disclosed in U.S. Patent No. RE 31,285, Van Turnhout. Rosin wool fiber webs and glass fiber webs are also useful, as are solution-spun or electrostatically sprayed fibers, particularly in microfiber form.

[0047] In some embodiments, larger fibers are used. For example, in some embodiments, fibers having an effective diameter of less than approximately 50 μm are used to form a wrinkled medium. In some embodiments, fibers having an effective diameter of less than approximately 40 μm are used to form a wrinkled medium. In some embodiments, fibers having an effective diameter of less than approximately 35 μm are used to form a wrinkled medium. In some embodiments, fibers having an effective diameter of less than approximately 30 μm are used to form a wrinkled medium. In some embodiments, fibers having an effective diameter of less than approximately 25 μm are used to form a wrinkled medium.

[0048] Nonwoven webs are porous, meaning that one outer surface of the nonwoven web is fluidly connected to the opposite outer surface of the same nonwoven web. This allows for the flow of vaporized fluid, air, or liquid through the nonwoven web. Nonwoven webs are coextensive, meaning that the web is a complete and continuous layer of nonwoven material without tears or ruptures.

[0049] In one embodiment, at least one of the nonwoven webs of the present disclosure comprises an electret fiber. An electret is a dielectric material having a quasi-permanent charge or dipole polarization. Electrets are typically improved by incorporating a charging additive into a polymer material and then inducing a charge in the polymer material using corona treatment, tribocharging treatment, hydrocharging treatment, or a combination thereof. In one embodiment, the electret fiber is a single-component fiber. In another embodiment, the electret fiber is a two-component fiber such as a sheath core or side-by-side. In one embodiment, the electret fiber is a sheath core fiber having a sheath layer extending equally on the core. In one embodiment, the core contains an additive that enhances the electrostatic charge. In one embodiment, the sheath contains an additive that enhances the electrostatic charge. In one embodiment, the electret fiber is side-by-side, and the fiber comprises two adjacent components along its length. In one embodiment, the electret fiber is a so-called “island in the sea” extrusion, where multiple fiber cores (i.e., one or more, two, four, or six or more cores) are distributed within a polymer matrix that also forms a sheath.

[0050] Many charge-enhancing additives for creating fiber webs containing electrets are known in the art. Exemplary charge-enhancing additives include pigments, light stabilizers, primary and secondary antioxidants, metal deactivators, hindered amines, hindered phenols, metal salts, triesters of phosphates, phosphates, fluorine-containing compounds, and combinations thereof. Preferably, the charge-enhancing additive is solid at room temperature to prevent migration within the resin and does not decompose at moderate temperatures. In one embodiment, the charge-enhancing additive is solid at temperatures of at least 25, 30, 40, 50, 60, 80, or 100°C. In one embodiment, the charge-enhancing additive does not decompose. For example, when heated to 235°C at a heating rate of 10°C / min using thermogravimetric analysis, there is no significant weight loss (i.e., less than 5%, 1%, or 0.1%) when measured under nitrogen.

[0051] Particularly preferred charge-enhancing additives include hindered amine-based additives, triazine-based additives, and hindered phenol-based additives.

[0052] Specific examples of hindered amine or triazine additives include (poly[[6-(1,1,3,3,-tetramethylbutyl)amino]-s-triazine-2,4-diyl][[(2,2,6,6-tetramethyl-4-piperidyl)imino]hexamethylene[(2,2,6,6-tetramethyl-4-piperidyl)imino]]) available from BASF (Ludwigshafen, Germany) under the trademark "CHIMASSORB 944", 1-(2-hydroxyethyl)-4-hydroxy-2,2,6,6-tetramethylpiperidine polycondensate dimethylsuccinate available from BASF under the trademark "TINUVIN 622", and "TINUVIN 622" Di-tert-butyl-4-hydroxybenzyl)-2-n-butylmalonate bis(1,2,2,6,6-pentamethyl-4-piperidyl), available from BASF under the trademark "CHIMASSORB 2020", polycondensate of dibutylamine-1,3,5-triazine-N,N'-bis(2,2,6,6-tetramethyl-4-piperidyl-1,6-hexamethylenediamine-N-(2,2,6,6-tetramethyl-4-piperidyl)butylamine, available from BASF under the trademark "TINUVIN 1577", and "UVINUL This includes N-substituted aminoaromatic compounds available under "T-150," particularly triamino-substituted compounds, such as 2,4,6-trianilino-p-(carbo-2'-ethylhexyl-1'-oxy)-1,3,5-triazine and 2,4,6-tris-(octadecylamino)triazine, also known as tristearylmelamine ("TSM").

[0053] A hindered phenol additive having a hydroxyl group as its terminal functional group. Hindered phenol additives are not particularly limited, and specific examples include pentaerythrityl-tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] (BASF Irganox 1010), octadecyl-3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate (BASF Irganox 1076), tris-(3,5-di-tert-butyl-4-hydroxybenzyl)-isocyanurate (BASF Irganox 3114), and 3,9-bis-{2-[3-(3-tert-butyl-4-hydroxy-5-methylphenyl)-propionyloxy]-1,1-dimethylethyl}-2,4,8,10-tetraoxaspiro-[5,5]undecane (Sumilizer-GA-80, Sumitomo Chemical Co., Ltd.).

[0054] Additional thermally stable organic triazine compounds or oligomers containing at least one nitrogen atom in addition to the nitrogen atom in the triazine ring are disclosed in U.S. Patents 6,268,495, 5,976,208, 5,968,635, 5,919,847, and 5,908,598 by Rousseau et al.

[0055] Further examples of charge-enhancing additives are provided in U.S. Patent Publication No. 2011 / 0137082 by Li et al., U.S. Patent No. 8,613795 by Li et al., U.S. Patent No. 7,390,351 by Leir et al., U.S. Patent No. 5,057,710 by Nishiura et al., and U.S. Patents No. 4,652,282 and 4,789,504 by Susumu et al., as well as U.S. Patent No. 8,790,449 B2 by Li et al.

[0056] The charge-enhancing additive can be added in any appropriate amount. The charge-enhancing additives of this disclosure may be effective even in relatively small amounts. Typically, the charge-enhancing additive is present in the blend of the thermoplastic resin and the charge-enhancing additive in amounts up to about 10% by weight, and more typically in the range of 0.02 to 5% by weight based on the total weight of the blend. In some embodiments, the charge-enhancing additive is present in the range of 0.1 to 3% by weight, 0.1 to 2% by weight, 0.2 to 1.0% by weight, or 0.25 to 0.5% by weight. <Nonwoven porous web containing membrane and adsorbent>

[0057] Alternatively or additionally, a porous membrane can be used instead of and / or in combination with a nonwoven fiber web. A wrinkled membrane can be wrinkled, for example, using the techniques described herein in relation to Figures 1-2. Multiple elastic filaments are placed between the membrane layer and one or more nonwoven porous webs. The membrane layer may be laminated or bonded with one or more nonwoven webs. Alternatively or additionally, the nonwoven porous web may contain an adsorbent material. Adsorbent particles may be placed on the surface of the nonwoven web or throughout its entire depth. An example of an adsorbent material is activated carbon. Other adsorbents that can be used include polymer adsorbents.

[0058] Table 2 shows the initial pressure drop (dP) and transmittance in NaCl and DO tests for nonwoven webs. At least two single sheets were measured for each flat nonwoven web.

[0059] In some embodiments of this specification, the initial pressure loss of the filter medium is less than 20 mmH2O at a face velocity of 14 cm / s. In some embodiments, the initial pressure loss of the filter medium is less than 10 mmH2O. In some embodiments, the initial pressure loss of the filter medium is less than 8 mmH2O. In some embodiments, the initial pressure loss of the filter medium is less than 6 mmH2O. In some embodiments, the initial pressure loss of the filter medium is less than 4 mmH2O. In some embodiments, the initial pressure loss of the filter medium is less than 2.0 mmH2O. In some embodiments, the initial pressure loss of the filter medium is less than 1.0 mmH2O. [Table 3] <Method for manufacturing wrinkled media>

[0060] In one embodiment, the wrinkled filter medium of the present application can be manufactured by stretching a plurality of elastic filaments 132. The filaments are generally not bonded to each other (e.g., the filaments of the present disclosure are not scrim). The plurality of elastic filaments 132 of the first series are held (e.g., using spacers 135, 137) and each filament is substantially parallel to each other and spaced at a predetermined distance apart. Generally, substantially parallel filaments should not come into contact with the nearest adjacent filament in the working part of the finished product. In one embodiment, the elastic filaments are held at intervals of at least 2, 4, 5, or 6 filaments per inch. In one embodiment, the elastic filaments are held at intervals of up to 8, 10, 12, 15, 20, or 25 filaments per inch. Generally, the filament spacing is chosen to achieve the desired shirring of the nonwoven web without causing large pressure changes.

[0061] The filament 132 can preferably be stretched to a desired length before reaching its elastic limit or yield point. As used herein, the % of elongation is defined as the difference between the length of the stretched filament and the length of the relaxed filament, divided by the length of the relaxed filament, and converted to a percentage. In one embodiment, the elastic filament stretches beyond 50, 75, 100, 150, 200, 250, or 300%. The filament may stretch beyond 250% as long as it does not exceed its elastic limit of deformation or breakage during the manufacture of the pleated medium disclosed herein.

[0062] The first and second nonwoven webs 134 and 136 are positioned on both sides of the stretched filament. The first and second nonwoven webs may be the same or different. The nonwoven webs are selected based on desired performance characteristics. The nonwoven webs may differ in terms of composition, base weight, fiber diameter, thickness, porosity, etc.

[0063] The first and second nonwoven webs 134 and 136 are directly bonded together, optionally using an adhesive as illustrated below, so that the first nonwoven web 134 is in contact with the second nonwoven web 136. In some embodiments, an adhesive is used to directly bond (or adhere) the first and second nonwoven webs to each other. Such adhesives may include pressure-sensitive adhesives or hot-melt adhesives. Pressure-sensitive adhesives are known in the art and are generally adhesives that bond when pressure (e.g., finger pressure) is applied at room temperature. Exemplary pressure-sensitive adhesives include natural latex or synthetic polymers such as (meth)acrylate. A commercially available pressure-sensitive adhesive is a spray adhesive traded as "3M Super 77 Multipurpose Adhesive" from 3M Corporation (Maplewood, Minnesota, USA). Hot-melt adhesives are thermoplastic polymers that are heated above their softening point and, when applied to a surface in a softened state, penetrate the surface and solidify to ensure bonding. Exemplary hot-melt adhesives include Bostik HM-9041, available from Bostik Inc. (Wowwatosa, Wisconsin, USA), and Tailored HM011BA, available from Tailored Chemical Products Inc. (Hickory, North Carolina, USA). In embodiments of the present application, when the adhesive is applied, the weight of the adhesive per unit area is less than the weight of the nonwoven web per unit area. In one embodiment, the weight of the adhesive per unit area is less than 0.5, 0.4, 0.3, 0.2, or 0.1% of the weight of the nonwoven porous fiber web per unit area in the article. Ideally, the adhesive should not impair the performance of the article and should be shrinkable, so that the adhesive can maintain cohesion (or keep the two layers of the nonwoven web bonded together) when the stretched filaments during manufacturing slacken. In one embodiment, in a wrinkled article, the adhesive is at least 1, 2, 4, 5, or 6 gsm (grams per square meter). In one embodiment, for a wrinkled article, the adhesive is up to 8, 10, 15, 20, 40, 60, 80, or 100 gsm.In another embodiment, the first and second nonwoven webs are directly welded to each other, with the first nonwoven porous fiber web in close contact with the second nonwoven porous fiber web. Such welding techniques are known in the art and include thermal welding or ultrasonic welding.

[0064] After the first and second nonwoven porous fiber webs are joined (or bonded), the tension of the stretched elastic filaments is released, and the resulting article becomes puckered or pleated. Typically, after the tension of the stretched elastic filaments is released, it may take several hours to several days for the structure to reach equilibrium and for the puckered article to reach its final puckered state. In one embodiment, heat may be used to achieve this stable state more quickly.

[0065] In addition to the first and second nonwoven webs, an additional layer (e.g., a third layer) may be added to the pleated article to provide additional functionality. The third layer may be added before the tension of the filaments is released, resulting in the third layer also being wrinkled or pleated. In another embodiment, the third layer is added after the tension of the filaments is released, resulting in the third layer being a flat layer bonded to the wrinkled or pleated article. An exemplary third layer includes a cover web, which is a layer used to protect the article beneath it from abrasion, soiling, etc. The third layer may also provide cosmetic and visual functionality.

[0066] In another embodiment, in addition to the first series of elastic filaments, a second series of filaments may be used—the first and second series of elastic filaments arranged non-parallel to each other (e.g., offset by at least 45 or 90 degrees).

[0067] In yet another embodiment, the series of elastic filaments may be stretched at different rates, and as a result, when the tension is released, the resulting wrinkled material includes regions with more wrinkles and regions with less wrinkles.

[0068] The articles of this disclosure are elastically stretchable under tension, meaning that when a wrinkled article is pulled in the same direction as the length of the elastic filament, the wrinkled article stretches (or flattens), and when the tension is released, the stretched article returns to its wrinkled shape. In one embodiment, the wrinkled article is elastically stretchable to at least two or three times its relaxed length. In some embodiments, the wrinkled article includes at least one portion that is elastically stretchable under a first tension, and a second portion of the wrinkled filter medium is under a second tension.

[0069] Because the articles of this disclosure have a wrinkled (or pleated) appearance, the resulting articles have a higher base weight than the original flat or wrinkle-free nonwoven porous fiber web. In one embodiment, the pleated articles of this disclosure have a base weight of at least 10, 15, 20, 30, 40, 50, 75, or 100 grams (gsm) per square meter. In one embodiment, the pleated articles of this disclosure have a base weight of up to 100, 125, 150, 175, 180, 200, 225, 250, 300, 325, 350, 375, 400, 425, or 450 gsm.

[0070] The articles of this disclosure are self-supporting—meaning they do not require additional layers to support a nonwoven web / filament / nonwoven web structure, optionally containing adhesive.

[0071] The wrinkled or pleated articles of this disclosure are useful for filtering fluids such as air or vaporized fluids. Such articles may be used to filter and remove undesirable particles from fluids, such as dust, mold, oily mist aerosols, cigarette smoke, pet dander, viruses, and bacteria.

[0072] The filter media described herein can have a variety of suitable air permeability. In one embodiment, the filter media has an air permeability of 2, 5, 10, 15, 20, 25, 30, 40, 50, 75, 100, 120, 150, 170, 200, 275, 300, 350, 400, or 450 CFM / sqft or higher. In some embodiments, the filter media has an air permeability of 450, 400, 350, 325, 300, 275, 250, 225, 200, 170, 150, 120, 100, 75, 60, 50, 40, 35, 30, or 25 CFM / sqft or lower. Combinations of the above ranges are also possible (for example, 20 CFM / sqft or more and 350 CFM / sqft or less, 35 CFM / sqft or more and 170 CFM / sqft or less, or 20 CFM / sqft or more and 350 CFM / sqft or less). Other ranges are also possible. The air permeability of the filter medium can be determined according to ASTM test standard D737 (1996). In some embodiments of this specification, the air permeability is less than 1000 CFM / sqft.

[0073] In embodiments of this disclosure, the article can be used as a respirator. For respirator applications, a wrinkled or pleated article can be formed into the shape of a face mask worn by an individual.

[0074] In another embodiment, the articles of this disclosure can be used as filters for furnaces, air conditioning units, or indoor air purification units.

[0075] The media S1 through S6 shown in Table 4 are pleated or wrinkled media webs using the flat media webs listed in Table 3. These were prepared according to the procedures disclosed in U.S. Provisional Patent Application 63 / 434365, filed December 21, 2022. [Table 4] <Manufacturing method for composite depth media> [Method 1 (Manufacturing of Type 1 media)]

[0076] This section describes a method for producing Type 1 composite deep media samples for testing.

[0077] Each composite deep medium sample has an opening of 144 cm. 2 3M® Adflo® filter plastic frame, or opening 102cm 2 The media layers were bonded to the frame of a 3M® Air-Mate® filter. Each layer constituting the composite deep media configuration was cut to the correct dimensions to fit the selected filter frame. Care was taken to ensure that each layer was properly identified and assembled to the filter in the correct order and orientation. The media layers were assembled to the selected frame, ensuring that the media layers were positioned in the correct orientation from inlet to outlet when the filter frame was assembled to the silica dust testing apparatus. The edges of the media layers were bonded to the filter frame using hot melt adhesive. For samples produced using a 3M® Air-Mate® filter frame, the hot melt adhesive was first distributed to the flat edges within the frame. The adhesive was distributed to coincide with the frame edges forming the outlet opening. Next, the outlet media layer was placed in the hot melt and sealed to the filter frame. The hot melt adhesive was distributed in the same pattern to the inlet surface of the outlet media layer, and the next media layer was placed in the hot melt, sealing that layer to the layer below. This step was repeated until all layers were sealed to each other and the exit layer was sealed to the filter frame, assembling the target composite deep media configuration to prevent leakage.

[0078] Due to the orientation of the filter in the test apparatus, samples generated using the 3M® Adflo® filter frame were assembled with the media layers in the reverse order from inlet to outlet compared to the Air-Mate® sample.

[0079] Figures 8A–8D show assembled composite media samples. Figure 8A shows a schematic diagram 800 of a housing 810 containing multiple filter media layers 820. Figure 8B shows a downstream view 830 of the assembled filter cartridge, and Figure 8C shows a test top view 840 of the assembled filter cartridge (for example, air passes through the surface in Figure 8C and is discharged through the surface in Figure 8B). Figure 8D shows a side view 850 of the assembled cartridge. [Method 2 (Manufacturing of Type 2 media)]

[0080] This section describes a method for manufacturing Type 2 composite deep media samples for testing.

[0081] Each composite deep medium sample has an opening of 102 cm². 2 The media layers were bonded to the plastic frame of the 3M® Air-Mate® filter. The individual layers constituting the composite deep media configuration were cut to the correct dimensions to fit the selected filter frame. Care was taken to ensure that each face of each layer and pleated layer was properly identified and assembled to the filter in the correct order and orientation. The edges of the media layers were assembled to the selected frame so that the media layers were positioned in the correct orientation from inlet to outlet when the filter frame was assembled to the silica dust testing apparatus. The media layers were bonded to the filter frame using hot melt adhesive. For samples produced using the 3M® Air-Mate® filter frame, the hot melt adhesive was first distributed to the flat edges within the frame. The adhesive was distributed to coincide with the frame edges forming the outlet opening. Next, the outlet media layer was placed in the hot melt and sealed to the filter frame. The hot melt adhesive was distributed in the same pattern to the inlet surface of the outlet media layer, and the next media layer was placed in the hot melt, sealing that layer to the layer below. This step was repeated until all layers were sealed to each other and the exit layer was sealed to the filter frame, assembling the target composite deep media configuration to prevent leakage.

[0082] The pleated media layers were assembled in their relaxed state. [Method 3 (Manufacturing of Type 3 media)]

[0083] This section describes a method for manufacturing Type 3 composite deep media samples for testing.

[0084] Each composite deep medium sample has an opening of 102 cm². 2 The media layers were bonded to the plastic frame of the 3M® Air-Mate® filter. The individual layers constituting the composite deep media configuration were cut to the correct dimensions to fit the selected filter frame. Care was taken to ensure that each face of each layer and pleated layer was properly identified and assembled to the filter in the correct order and orientation. The media layers were assembled to the selected frame so that when the filter frame was assembled to the silica dust testing apparatus, the media layers were positioned in the correct orientation from inlet to outlet. The media layers were bonded to the filter frame using hot melt adhesive. For samples produced with the 3M® Air-Mate® filter frame, the hot melt adhesive was first distributed to the flat edges within the frame. The adhesive was distributed to coincide with the frame edges forming the outlet opening. Next, the outlet media layer was placed in the hot melt and sealed to the filter frame. The hot melt adhesive was distributed in the same pattern to the inlet surface of the outlet media layer, and the next media layer was placed in the hot melt, sealing that layer to the layer below. This step was repeated until all layers were sealed to each other and the exit layer was sealed to the filter frame, assembling the target composite deep media configuration to prevent leakage.

[0085] All the pleated media layers were assembled in their relaxed state. [Method 4 (Manufacturing of the respirator)]

[0086] This section describes a method for manufacturing a respirator using a composite deep-layer medium sample for testing.

[0087] The cup-shaped disposable respirator is initially manufactured by placing a specified medium on a pre-formed cup-shaped shell such that the wrinkles on the shell are generally perpendicular to the direction from the nose to the jaw. The cup-shaped shell has a volume of approximately 230 milliliters and is made of the same shell material as the respirator available under the product name "3M Particulate Respirator 8210" which is available from 3M (Maplewood, Minnesota, USA). To conform to the curvature of the cup shape, the wrinkled medium is arranged to form creases on both sides adjacent to the staple or weld area which is for the headband of the respirator. Next, the wrinkled medium and the shell are welded around the perimeter of the cup to form the cup-shaped respirator.

[0088] The pleated or wrinkled medium can be welded to the shell with the wrinkles oriented in any other direction. <Test Method>

[0089] To evaluate filtration performance, various filtration test protocols have been developed for different filters and applications.

[0090] Specific clogging tests are specified for devices conforming to EN standards. EN 143 standard is applicable to air-purifying respirators, and EN 12941 and EN 12942 standards are applicable to powered air-purifying respirators. In the EN RPD standard, dolomite is used as the test dust for the clogging test, and in the NIOSH RPD standard, silica dust is used as the test dust for the clogging test. Dolomite is defined in clause 8.8 of EN 143:2000 as DRB 4 / 15 dolomite with a particle size mass distribution of 95% < 22μm and 99.5% > 1.8μm. The allowable concentration of the test is 300 - 500 mg / m 3 In the APR, the dosage is a mass dosage of 263 mg*h / m 3Alternatively, it may be expressed as when the filter resistance exceeds a threshold. In PAPR, the dosage is based on the headtop type, filter type, and filter class, ranging from 100 to 400 mg*h / m². 3 This is the range. Many filter types are Tx3P or Tx3(Gas)P, with a range of 100-200 mg*h / m². 3 The total clog-blocking dose is required. According to the NIOSH RPD standard for PAPR clogging tests, it is 220 mg*h / m². 3 A certain dosage is required. There is no NIOSH RPD standard regarding APR clogging. For many filter types, the clogging dosage for silica dust is greater than that for dolomite. Furthermore, the silica dust used has a smaller geometric mean particle size than dolomite. Simply put, the silica dust test is a long-duration test using finer dust, while the dolomite test is a short-duration test using coarser dust. At PAPR flow rates, the silica dust test typically results in an increase of approximately 2 to 4 times in the airflow resistance of the filter compared to dolomite.

[0091] The filters described herein can be configured to filter particles of various compositions and particle size distributions. RPD standards generally concern the breathable size range of 0.1 to 1.0 μm. For example, dust generated from wildfires consists of both fine, breathable dust and coarse, irritating dust. It is not uncommon for PM1.0, PM2.5, and PM10 sized dust particles (1.0 μm, 2.5 μm, and 10 μm) to be present in equivalent mass ratios. While RPD evaluation generally focuses on particles smaller than 1.0 μm, it is reasonable to adjust the deep media solution to prevent clogging for particles up to 10 μm. Particles larger than 10 μm are either not present far from the source, or if working close to the source, sacrificial pre-filters are used to capture these coarser particles.

[0092] The following test methods were used to evaluate examples of media and respirators. Unless otherwise specified, for each example (EX) and comparative example (CE), at least two samples were tested and averaged.

[0093] Unless otherwise noted, all initial and loaded NaCl permeation and pressure loss tests of the webs were performed at a face velocity of 13.9 cm / sec. The performance of the media webs described in Table 3 are actual measured values based on the described test methods. <NaCl and DOP Initial Tests and Quality Factor>

[0094] The pressure loss and permeability of the media web can be evaluated using a challenge containing NaCl or DOP (dioctyl phthalate) particles, supplied at a flow rate of 85 liters per minute (LPM), using a TSI (trademark) Model 8130 High Flow Automated Filter Tester available from TSI Inc. (Shoreview, Minnesota, USA). The pressure loss (dP, mmH2O) through the filter media or filter sample can be measured using an MKS pressure transducer available from MKS Instruments (Andover, Massachusetts, USA). <l

[0095] In the NaCl instantaneous testing using particles with a diameter of 0.075 μm at 85 liters per minute (LPM), particles are generated from a 2% NaCl solution to provide an aerosol containing particles at an airborne concentration of about 16 - 23 mg / m<l 3 . The automated filter tester is operated with both the heater and the particle neutralizer on. The initial NaCl permeation and pressure loss tests last about 19 seconds. <l

[0096] <l In the DOP test, the aerosol may contain particles with a nominal diameter of about 0.185 μm at a target concentration of about 100 mg / m<l 3 . The automated filter tester is operated with both the heater and the particle neutralizer off. The initial DOP permeation and pressure loss tests last about 21 seconds.

[0097] NaCl or DOP particles have a diameter of 11.4 cm or an opening of 102 cm. 2 The media sample is forced to pass through at a speed of 85 LPM.

[0098] The transmittance of DOP or NaCl is defined by Equation 2: Transmittance (%) = (Concentration downstream / Concentration upstream) × 100 Equation 2

[0099] Using the permeability and pressure drop of DOP or NaCl, the quality factor "QF" is calculated using Equation 3.

number

[0100] A higher initial QF value indicates better initial filtration performance. A decrease in QF value correlates effectively with a decrease in filtration performance. <Silica Loading Test>

[0101] The silica particles used in the load test followed the conditions described in NIOSH Silica Dust Test - 42CFR Part 84.179. The test flow rates varied for different composite deep media samples. The silica size distribution and challenge concentration, the face velocity of the test flow through the composite deep media, and the test time are summarized below. The silica particles have a geometric mean of 0.4 to 0.6 microns, with over 99% being less than 270 mesh (i.e., 53 microns), and a standard deviation of less than 2. Challenge: Average concentration of silica in the air: 50-60 mg / m³ 3 . Total exam time: 240 minutes unless otherwise specified. Test flow surface velocities: 8.6 cm / s, 7 cm / s, and 14 cm / s.

[0102] The silica concentration in the test chamber was measured by the gravimetric method at approximately one-hour intervals before and during the test and was measured until the end of the test. The measured concentrations were averaged to confirm that the requirements were met. To monitor the silica concentration more frequently during the loading process, a Casella CEL-712 aerosol monitor (available from Cole-Parmer, Vernon Hills, IL 60061, USA) were used. The volumetric flow rate is measured using a TSI 4040 mass flow meter (available from TSI Inc., Shoreview, Minnesota) and normalized to standard conditions of 101.3 Pa and 21.1 °C. A manometer such as an ExTech HD755 (1-800-Grainger by Grainger) was used downstream of the media sample to measure pressure loss during loading. A customized computer program automatically acquired flow and pressure loss data at pre-set time intervals from seconds to tens of seconds.

[0103] The silica transmission rate is defined by Equation 4: Transmission rate (%) = (weight downstream / weight upstream) × 100 Equation 4 <NaCl Loading Test>

[0104] The loading test was performed on a TSI® Model 8130 High-Speed Automated Filter Tester provided by TSI Incorporated (Shoreview, Minnesota, USA) according to the procedure described in the tester manual. The samples were subjected to a continuous NaCl challenge of 85 LPM with the particle ionization device operating. The flat samples tested had an exposed area of 100.2 cm at a nominal face velocity of 13.9 cm / second for flat and wrinkled media sheets. 2 of exposed area.

[0105] The samples can be loaded with NaCl particles until the pressure loss reaches at least twice the initial pressure loss, and a calibrated photometer is used at the inlet and outlet of the filter to measure the particle concentration and the particle transmission rate through the filter.

[0106] The initial NaCl efficiency of the filter medium according to the embodiments herein may be at least 40% in some embodiments. In some embodiments, the initial NaCl efficiency is at least 50%. In some embodiments, the initial NaCl efficiency is at least 60%. In some embodiments, the initial NaCl efficiency is at least 70%. In some embodiments, the initial NaCl efficiency is at least 75%. In some embodiments, the initial NaCl efficiency is at least 80%. In some embodiments, the initial NaCl efficiency is at least 90%. In some embodiments, the initial NaCl efficiency is at least 95%. In some embodiments, the initial NaCl efficiency is at least 98%. In some embodiments, the initial NaCl efficiency is at least 99%. <Welding fume load test>

[0107] Welding fumes are generated during the welding process when metal is heated and melted using an electric arc, gas torch, etc., and some of the heated metal evaporates and immediately condenses, forming very small particles in the air. These small particles can sometimes combine with each other to form longer aggregated chains. In this test, welding fumes were generated by flux-core arc welding (FCAW) using mild steel wire on a mild steel base metal.

[0108] FCAW was performed using CO2 gas. Mild steel base metal (SS400, Fe: 98%, C: 0.30%, Mn: 1.60%) was placed on a base turntable, and 1.2 mm flux core wire (SF-71, AWS E71T-1, Hyundai Welding Co., Korea) was fed to the torch at a speed of 13 cm / s. The welding machine (IB-350, Chowell Co., Korea) was set to produce an average current of 232 A and a voltage of 22 V. The welding machine was operated in a 3-second on, 60-second off cycle, and the average fume concentration was 86.0 mg / m³. 3 (Standard deviation (SD)25.4mg / m 3The welding parameters, such as welding time, wire feed rate, welding speed, torch angle, and the distance between the contact tube and the workpiece, were controllable.

[0109] The welding fumes were not neutralized. The welding fume particles had a CMD (median diameter) of 210-221 nm. The laboratory conditions were set to 23°C (21-24°C) and 20% (17-22%) RH.

[0110] The fume generation system used consisted of a welding chamber connected to a test chamber, into which welding fumes were drawn. Composite media samples were mounted in a test chamber with a 10 cm diameter opening. A filter efficiency tester (SIBATA, AP-634A, Japan) and a manometer (OKANO, DMP-202N, Japan) were used simultaneously to measure filter transmittance and pressure drop. A constant flow rate of 66 LPM, corresponding to a face velocity of 14 cm / s, was applied to the composite deep media samples. A constant flow rate of 85 LPM was applied to the respirator samples. At least two replicates were tested for each media or respirator sample. Flow rates were controlled using a Dwyer Series RMC-104-CPF Rate-Master Flowmeter connected to a GAST rotary vane pump (Model 0523-101Q-SG588DX). A computer program was developed using LabVIEW to acquire analog signals from the upstream and downstream photometers and manometers.

[0111] The load test was stopped when the cumulative load of welding fume particles reached approximately 200 mg. The permeability of silica is defined by Equation 5: Transmittance (%) = (Downstream weight / Upstream weight) × 100 Equation 5 <Load Quality Factor>

[0112] The Load Quality Factor (LQF) at specific face velocities for silica, welding fumes, and NaCl particles was calculated to compare composite deep medium samples based on particle capture capacity per unit surface area and pressure loss increase. This is defined by Equation 6.

number

[0113] "Area" is the actual surface area of ​​a flat media layer or a pleated or corrugated media structure. "Area" is the projected surface area for shirred or wrinkled media layers, as they are substantially flat sheets. "Pressure loss delta" is the increase in pressure loss at the end of the load, determined by the total load time or total load weight. The unit of LQF is [mg / cm²]. 2 [ / mmH2O]. At a given flow rate and surface velocity, a higher LQF indicates that the capture of aerosol particles by the medium sample is higher for the same increase in pressure loss per unit area.

[0114] Details on how to measure these values ​​are described in the Examples section.

[0115] Figures 5A to 5B are schematic diagrams showing cutaway views of filter media according to embodiments of this specification. Figure 5A shows a cutaway view of a filter medium 200 having an inlet or upstream surface 202 and an outlet or downstream surface 204. Air passing through the filter medium passes through the inlet surface 202, through the filter layer 210, then through the filter layer 230, and is discharged from the outlet surface 204. In some embodiments, layer 210 is a high-load capacity layer and layer 230 is a high-efficiency layer.

[0116] Layers 210 and 230 are shown as different parts of the filter medium 200. In some embodiments, each layer 210 and 230 is manufactured separately, and then the filter medium 200 is assembled. In some embodiments, a dividing material such as scrim, net, or other suitable material is present between layers 210 and 230. However, in some embodiments, the materials for both layers 210 and 230 are assembled so that layers 210 and 230 are formed simultaneously, and then the filter medium 200 is constructed. In some embodiments, the filter medium 200 is die-cut.

[0117] The filter medium 200 is depicted as having flat surfaces 202, 204. However, it is explicitly considered that layers 210, 230 may be composed of nonwoven material that can interleave each other. As used herein, “surface 202” and “surface 204” are intended to refer to contact surfaces located on the front (or back) side of the filter layers 210, 230 and in contact with the majority of the nonwoven web.

[0118] In some embodiments, the filter layer 230 is composed of at least one wrinkled media sheet. The increased surface area of ​​the wrinkled media sheet helps ensure that the filter layer 230 is sufficiently efficient for its intended application.

[0119] In some embodiments, the filter layer 210 is composed of at least one wrinkled media sheet. The increased surface area of ​​the wrinkled media sheet can increase the particle loading capacity of the filter layer 210. This can enable a higher loading capacity with fewer media sheets. Alternatively, a filter medium 200 having a wrinkled media layer 210 can have the same capacity as a filter medium 200 without a wrinkled media layer, while having lower pressure loss.

[0120] In some embodiments, both filter layers 210 and 230 are composed of a wrinkled medium. Filter layer 210 may be formed from one or more wrinkled medium sheets configured for high particle loading capacity. Filter layer 230 may be formed from one or more wrinkled medium sheets configured for high filtration efficiency.

[0121] Figure 5B shows a schematic cutaway of another embodiment of the filter medium 250. The filter medium 250 has three layers: an inlet or upstream layer 260 (having an inlet surface 252), an outlet or downstream layer 280 (having an outlet surface 254), and an intermediate layer 270. Air passes through the filter so that it first comes into contact with surface 252, then with layers 260, 270, and 280, and is discharged from surface 254.

[0122] The intermediate layer 270 is in contact with the exit layer 280 on one side and with the inlet layer 260 on a second side. In some embodiments, layers 260, 270, and 280 may be formed independently and then combined to form the filter 250. In another embodiment, two or more layers 260-280 may be formed simultaneously. For example, one or more sheets of nonwoven media layers 260-280 may be stacked together and then sealed together.

[0123] In some embodiments, one or more of layers 260-280 may be composed of a wrinkled medium. An inlet layer 260 formed of a wrinkled medium may have a higher particle loading capacity than a similarly constructed inlet layer formed of a flat nonwoven material. Alternatively, the inlet layer 260 may have the same loading capacity as an equivalent inlet layer formed of a flat nonwoven material, but with lower pressure drop. An outlet layer 280 formed of a wrinkled medium may provide similar efficiency to an equivalent outlet layer 280 with lower pressure drop, but with higher filtration efficiency due to increased surface area.

[0124] The intermediate layer 270 may consist of a material designed for high-load capacity loading, high-efficiency loading, or a combination of both. In some embodiments, the intermediate layer 270 may function as a second high-load capacity filter layer or a first high-efficiency layer. Generally, layers 260, 270, and 280 are designed to capture particles of different size ranges.

[0125] Figures 5A and 5B show filters 200 and 250 having layers of equal thickness. However, in some embodiments, it is explicitly considered that layers 210, 230 or 260-280 have different thicknesses.

[0126] Each wrinkled media layer may have a low height or thickness profile. In some embodiments, the wrinkled media layer has an average thickness of less than approximately 25 mm. In some embodiments, the wrinkled media layer has an average thickness of less than approximately 20 mm. In some embodiments, the wrinkled media layer has an average thickness of less than approximately 15 mm. In some embodiments, the wrinkled media layer has an average thickness of less than approximately 10 mm. In some embodiments, the wrinkled media layer has an average thickness of less than approximately 6 mm. In some embodiments, the wrinkled media layer has an average thickness of less than approximately 3 mm. In some embodiments, the wrinkled media layer has an average thickness of less than approximately 2 mm. In some embodiments, the wrinkled media layer has an average thickness of approximately 1 mm.

[0127] Generally, the high-load capacity layer of a filter medium captures particles by a deep filtration mechanism. The high-load capacity layer can be formed from a nonwoven sheet made from a fibrillated film, a spunbond or bulky spunbond sheet, staple fibers, or other suitable fibers depending on the particles to be removed. The high-load capacity layer of the filter medium is expected to capture most airborne particles with low pressure loss.

[0128] Respiratory filters are generally designed to remove various particles by filtration. High-load capacity layers are designed to remove most particles, but may be less efficient at capturing smaller particles. In some embodiments herein, high-load capacity layers are less effective for submicron-sized particles.

[0129] In some embodiments, the high-capacitance filter layer includes at least some charged fibers. In some embodiments, the high-capacitance filter layer includes one or more sheets of a nonwoven medium having charged fibers.

[0130] In some embodiments, the high-load capacity filter layer consists of one or more layers of wrinkled media, which significantly increases the surface area per square inch of the filter.

[0131] The high-load capacity layer of a filter medium is generally designed to trap particles within the depth of the layer, avoiding aggregation on the layer's surface, which increases pressure loss and necessitates premature replacement. In some embodiments, the high-load capacity layer of the filter medium is composed of a bulky nonwoven fabric, for example, with a solidity of less than 12%, allowing particles to move into the layer before becoming embedded.

[0132] The high-efficiency layer of a filter medium typically captures particles with one or more sheets of a nonwoven medium having smaller fibers. The high-efficiency layer can be formed from sheets of nonwoven material composed of meltblown fibers, microglass fibers, nanofibers, or other suitable fibers. In some embodiments, the high-efficiency layer may include a film.

[0133] In some embodiments, the high-efficiency filter layer includes at least some charged fibers. In some embodiments, the high-efficiency filter layer includes one or more sheets of a nonwoven medium having charged fibers.

[0134] In some embodiments of this specification, a high-load capacity layer captures the majority of particles in the air being filtered. In some embodiments, an efficiency layer has a lower capacity than the high-load capacity layer of the filter medium.

[0135] In some embodiments of this specification, a transition layer exists between a high-load capacity layer and an efficiency layer. The transition layer may consist of a nonwoven medium having higher efficiency than the high-load capacity layer. In some embodiments, the transition layer has lower efficiency than the high-efficiency layer. In some embodiments, the transition layer has higher capacity than the high-efficiency layer. The transition layer may consist of one or more bulky nonwoven fabrics. The transition layer may consist of one or more wrinkled media, providing a higher surface area and therefore higher capacity than a flat nonwoven media layer.

[0136] While depth loading and surface loading are generally described above, it is explicitly considered that filter media often possess aspects of both filtration techniques. For example, a high-efficiency layer may have multiple material sheets, so that some particles pass through the first layer and are captured within the second layer. Furthermore, it should be noted that some filter media may balance capacity and efficiency. In some embodiments, a transition layer between a high-load capacity layer and a high-efficiency layer may have both high-efficiency and high-load capacity properties to capture specific particle challenges.

[0137] In some embodiments, the filter layers are manufactured separately and then attached using sewing, bonding, heat bonding, welding, die cutting or other suitable mechanisms. In some embodiments, the media sheets forming each filter layer are assembled and formed into a filter medium in one step.

[0138] The filter layer in the embodiments herein consists of a sheet of charged split fiber medium, spunbond medium, blown microfiber, fibrillated film, or other suitable material. A fibrillated film and a method for producing the same are described in U.S. Patent RE32171, published June 3, 1986. Note that in embodiments using fibers formed from a fibrillated film, the fibers have a rectangular cross-section.

[0139] In some embodiments of this specification, fibrillated film fibers are available from 3M Company. The fibrillated film fibers described herein have a rectangular cross-section of 10 micrometers (μm) × 40 μm and, due to their excellent electrostatic maintenance ratio, provide these fibers with excellent particle capture properties. However, it is explicitly considered that other dimensions of fibrillated film fibers may be used according to the embodiments described herein.

[0140] In demanding filtration applications, it is highly desirable for the filter medium to provide high efficiency, high particle load, and low pressure loss. However, these properties are inherently competitive attributes. For example, high-efficiency media typically result in high pressure loss, and high-load capacity media can also lead to increased pressure loss.

[0141] The filter media described herein have two or three distinct layers. However, the possibility of additional layers is explicitly considered. For example, the filter media may have four, five, or six layers. The layers may transition from high-load capacity attributes to high-efficiency attributes as they move from the inlet to the outlet. The filter media according to the embodiments herein may have six or more layers. In some embodiments, each layer differs from adjacent layers in one or more parameters. Parameters that distinguish one layer from an adjacent layer may include fiber material, fiber size, fiber density, bulk, type of nonwoven or membrane, number of media sheets in the layer, or other parameters that affect capacity or efficiency.

[0142] The filters described herein may have one or more layers of wrinkled medium. The wrinkled medium layers may differ from each other by additional parameters specific to the wrinkle-forming process, such as the material of the elastic filaments, diameter, degree of density in the relaxed state, elongation ratio, adhesive, or other appropriate parameters.

[0143] Figures 6A-6B show schematic cross-sectional views of a filter medium manufactured according to embodiments of this specification. The filter medium 300 is shown having three layers between an inlet or upstream surface 306 and an outlet or downstream surface 304. Air passing through the filter medium 300 first comes into contact with surface 302, then passes through layers 306, 308, and 310, and is discharged from the projected outlet surface 304.

[0144] The filter 300 illustrates an embodiment in which layers 310 and 308 are formed from a wrinkled medium. Figure 6A-1 shows a schematic diagram in which a single sheet of wrinkled medium forms each of the layers 308, 310. However, it is explicitly considered that the filter layers, e.g., layer 308 or 310, may be formed from multiple sheets of wrinkled medium. Figure 6A-1 also shows a separation layer 312 between layers 308 and 310. In some embodiments, the separation layer 312 is a scrim, net, or other suitable separator. However, it is explicitly considered that not all embodiments of this specification include a separation layer.

[0145] Although the filter 300 is shown having a separator between layers 308 and 310, in some embodiments it is explicitly considered that the separation layer 312 is absent. In such embodiments, the lines representing the separation mechanism 312 in Figure 6A-2 may show how adjacent layers of the wrinkled medium interact due to how the wrinkled medium sheet is folded during the crumpling process. In some embodiments, the first layer of the wrinkled medium may at least partially overlap the second layer of the wrinkled medium along the thickness 314 of the filter 300.

[0146] As shown in Figure 6A-1, two different types of wrinkled media are used, one for layer 308 and the other for layer 310. The compositions of layers 308 and 310 may differ in terms of fiber type, fiber thickness, fiber density, type of elastic filament, spacing between adjacent elastic filaments, elongation of elastic filaments during the wrinkle processing, or other adjustable parameters.

[0147] Figure 6A-2 shows an example of a filter 320 formed by the layers shown in Figure 6A-1, which includes, for example, an outer layer of a flat nonwoven medium and transition and inner layers formed of a wrinkled medium.

[0148] Figures 6B-1 and 6B-2 show a filter having three wrinkled media layers according to an embodiment of this specification. Schematic diagram 350 of the filter shows the configuration of filter 370. Filter 350 includes three layers: an outer layer 356, a transition layer 358, and an inner layer 360. The outer surface is indicated by line 352.

[0149] It is explicitly considered that, for layers of wrinkled material, the surface does not necessarily have to be a flat surface. In the case of a wrinkled medium, surface 352 can be defined as a theoretical surface. Similarly, line 362 represents a theoretical surface. A theoretical surface can be defined as (1) the average height of individual wrinkles measured from the elastic filament, or (2) the surface that the majority of the surface of the wrinkled medium layer contacts during use. In some embodiments, it is explicitly considered that adjacent layers may overlap each other, for example, one or more wrinkles in the first layer extending into the second layer along the thickness 364 of filter 350. Also, in some embodiments, it is considered that there may be a physical separation 362 between any or both of layers 356, 358 or 358, 360.

[0150] Layers 356-360 are shown in Figure 6A-1 as having similar thicknesses measured along the filter thickness 314. However, in some embodiments, different layers have different thicknesses. For example, the high-load capacity layer may consist of more or thicker sheets of wrinkled media than the high-efficiency layer.

[0151] Figure 6B-2 shows an example of a filter 370 formed by the layers shown in Figure 6B-1, which includes, for example, an outer layer of a flat nonwoven medium and transition and inner layers formed of a wrinkled medium.

[0152] The filters described herein can be used in the manufacture of disposable respirators and in filter packs. The filters herein consist of one or more layers made of a wrinkled medium and provide a larger surface area for particle collection without the need to add more fabric layers.

[0153] The wrinkled layer here is composed of a wrinkled nonwoven medium, manufactured according to the method described in Figures 3-4, which is described in more detail in the Examples section of U.S. Provisional Patent Application 63 / 434365 filed December 21, 2022, and is incorporated herein by reference. Different fibers and different elastic filaments may be used depending on the required capacity and / or efficiency.

[0154] The fibers used in the embodiments herein may have an effective fiber diameter of 4 μm to 100 μm. In some embodiments, the fibers have an effective fiber diameter of 4 μm to 50 μm. In some embodiments, the fibers have an effective fiber diameter of 10 μm to 40 μm.

[0155] Figure 7 shows a method for forming a filter according to embodiments of this specification. Method 400 may be useful for filters for disposable respirators, PAPRs or other breathing devices, or for other filtration applications. A filter formed using Method 400 is a composite filter composed of at least two different materials.

[0156] In block 410, the high-load capacity zone of the filter is formed. The high-load capacity zone is formed of one or more layers, each of which may contain one or more nonwoven fabric sheets. In some embodiments, the nonwoven fabric is wrinkled (shown in 402). In some embodiments, the nonwoven fabric is flat (shown in block 404). Other media may be used, including glass fiber media, membranes, or other filtration or adsorption materials such as sorbent materials (shown in block 406).

[0157] In block 420, the high-efficiency zone of the filter is formed. The high-efficiency zone is formed of one or more layers, each of which may contain one or more nonwoven fabric sheets. In some embodiments, the high-efficiency zone is composed of a wrinkled nonwoven medium (shown in block 412). In some embodiments, the high-efficiency zone is composed of one or more flat nonwoven fabric sheets (shown in block 414). Other suitable filtration media, such as glass fiber media, membranes, or other filtration mechanisms can also be used (shown in block 416).

[0158] In block 430, the filter is assembled. The formation of the filter involves arranging the high-load capacity zone and the high-efficiency zone so that the air to be filtered first passes through the high-efficiency zone before passing through the high-efficiency zone. In some embodiments, the high-load capacity zone is formed within the high-load capacity layer, the high-efficiency zone is formed within the high-load capacity layer, and then the two layers are sealed together. In some embodiments, the nonwoven sheets of each zone are assembled as a stack of unsealed sheets and then sealed together in one step.

[0159] As shown in block 432, sealing includes die cutting, welding, joining, sewing, a combination thereof, or other suitable sealing mechanisms.

[0160] Filter assembly also includes forming the filter medium into the desired shape. For example, a cup shape for a cup-type disposable respirator, or sealing panels together for a vertically folding or horizontally folding disposable respirator. If the filter is used in a PAPR or other device with a replaceable filter cartridge, assembly includes forming the filter to fit into the cartridge or other housing. Filter assembly may also include other steps, as shown in block 436.

[0161] Using a wrinkled medium in one or more layers of a composite filter offers several advantages. As described herein, a wrinkled medium increases the surface area per square inch (or square centimeter) of the filter compared to a flat medium. This improves user comfort by providing a higher capacity without compromising comfort. Another advantage of using a wrinkled medium lies in the assembly stage, for example, block 430 of method 400. Conventional filters are often pleated before being placed in the filter cartridge or housing. The pleating process can be a bottleneck in the manufacturing process. Using a wrinkled medium provides more surface area with fewer sheets, eliminating the need for mechanical means (pleating or other folding techniques) to create surface area.

[0162] Because wrinkled media can provide the same volume with fewer sheets of nonwoven media, less physical media needs to be housed within the cartridge or housing. This means that using wrinkled media can enable smaller housings than those required for conventional pleated filter media.

[0163] In the embodiments described herein, filters comprising the composite media layers described herein exhibit high silica loading capacity that fully meets the silica testing requirements according to the NIOSH42CFR84 procedure, have a final pressure loss 20–60% lower than current pleated packs, and maintain an initial DOP photometric and CPC filtration efficiency of 99.95% or higher. Filters manufactured according to the embodiments described herein also exhibit high salt loading capacity.

[0164] Depending on the requirements of a particular filter application, it is explicitly considered that the composite medium may be modified to reduce the number of layers, or to have the same number of layers but with each layer having different properties of base weight, thickness, or solidity, as described herein.

[0165] Furthermore, non-pleated media sheets can be better adapted to curved or irregular shapes. Gas and vapor filter devices with circular, elliptical, or other curved housings can benefit from the filters described in the embodiments herein, which is generally not possible with pleated packs.

[0166] While much of the description in this specification focuses on the use of filter media for respiratory applications, it is explicitly considered that the filter media constructed herein may also be useful in other examples. Figures 9–11 illustrate other applications in which the embodiments of filter media described herein may be particularly useful.

[0167] Figure 9 shows an indoor air purifier according to several embodiments of this specification. Specifically, embodiments of the filter media described herein may be particularly useful as a pre-filter layer placed before the main pleated filter for use in an indoor air purifier (RAP). Typically, the main RAP filter has high-density pleats (e.g., about 3 to about 8 per inch), and the filter media used in RAP filters is usually HEPA grade, with an efficiency of at least 99.97% for a particle size of 0.3 μm. Such filters are often expensive, and consumers and manufacturers are looking for ways to extend the lifespan of the main pleated filter. Currently, several types of pre-filters exist on the market, including mesh screens (e.g., as shown in International Publication WO2017161530, published September 28, 2017, with Figure 3 and related explanations incorporated here by reference) and carbon pre-filters made of porous open-cell foam or low-density flat nonwoven fabric coated with activated carbon (a structure similar to Scotch-Brite® sold by 3M). The filtration media described herein are formed from media with lower airflow resistance compared to HEPA media, allowing for the creation of pre-filters with high dust retention capacity that help capture large amounts of dust during use and extend the life of the primary filter. Pre-filters may be replaced or cleaned at more frequent service intervals than primary filters. Wrinkled media pre-filters help maintain lower airflow resistance throughout the life of the air purifier compared to using pleated HEPA filters alone. Such pre-filters can be used with planar, cylindrical, or other shaped RAP filters. Various structures such as adhesives, clips, and hooks may be used to help attach the pre-filter to the main filter or the housing of the air purifier. In certain embodiments, the wrinkled medium may be formed from a medium suitable for functioning as the main filter of an indoor air purifier. Figure 9 shows an exploded view of the RAP, in which the air first passes through a pre-filter formed of a wrinkled filter medium before encountering the primary filter of the RAP.

[0168] Figures 10A–10D show different HVAC filter configurations according to several embodiments of this specification. The wrinkled filter medium can be used in a flat form as the filtration layer of the HVAC filter in both residential and commercial type HVAC filters. A residential filter with a nominal thickness of 1 inch may be particularly suitable for the embodiments of the wrinkled filter medium described herein. By using the wrinkled filter medium, the surface area of ​​the filter medium within the filter structure is effectively increased, and the larger medium surface area reduces the airflow resistance of the filter structure and improves the dust retention capacity of the filter medium.

[0169] The wrinkled filter media according to the embodiments of this specification may be suitable for replacing several existing filter media structures commonly found in HVAC filters, such as flat sheet media as shown in Figure 10A, sinusoidal pleats as shown in Figure 10B, and triangular pleats as shown in Figure 10C.

[0170] The wrinkled filter medium according to the embodiments of this specification can be used in expandable or refillable filters, as shown in Figure 10D, and by utilizing the inherent elasticity of the medium, the medium or filter elements can be shipped in a compressed or folded state, thereby reducing shipping costs and package size. Furthermore, by using the wrinkled filter medium in expandable / refillable filters, it is also possible to provide filters that are sized in one or more major dimensions. For example, the filter medium here can be stretched from a 20 x 20 inch filter element to function as a 20 x 25 inch filter element.

[0171] Wrinkled media can be incorporated into filters in frameless or framed structures. Suitable filter frame types for HVAC filters include box frames (e.g., Figure 1 and related description in US2012 / 0272829, incorporated here by reference), channel frames (e.g., Figure 6 and related description in International Publication WO2015 / 034799, incorporated here by reference), other strip frames (optionally nestable, e.g., Figure 1 and related description in US2015 / 0265957, incorporated here by reference), and refillable frames or housings (e.g., Figure 9 and related description in US2017 / 0182445, incorporated here by reference).

[0172] HVAC filters with performance exceeding entry-level levels almost universally incorporate pleated filter media to increase the surface area of ​​the filter medium, thereby reducing the airflow resistance of the filter, increasing the available area on the filter for capturing dust and other contaminants, and extending the filter's useful life. Filter pleats are also used to maintain a certain level of airflow resistance while incorporating a high-efficiency filter medium into the filter, as high-efficiency media generally tend to have high airflow resistance.

[0173] A wrinkled medium that itself has a three-dimensional shape may be further pleated and incorporated into an air filter. This expanded surface area structure may offer further advantages in the filter's airflow resistance, dust retention capacity, and / or efficiency. A suitable pleat density may range, for example, from 0.3 to 5 pleats per inch.

[0174] Figures 11A-11B show cross-sectional views of filters according to some embodiments of this specification. Figure 11A shows an example of a prior art filter medium relating to a filter medium assembly that includes a highly open wire mesh or screen, one or more adhesive strands, etc., which is bonded to the wrinkled filter medium and pleated together with the wrinkled filter medium itself in order to improve the pleatability of the wrinkled filter medium. The wire mesh or screen (or other additional component) may prevent the pleated version of the filter medium assembly from being folded again from an expanded state.

[0175] Figure 11B shows a highly open wire mesh in which pleated, wrinkled filter media are bonded or otherwise connected. Such a configuration provides two different three-dimensional compression techniques for nonwoven articles—first by creasing, and then by pleating the wrinkled media.

[0176] Pleated, wrinkled media may be suitable for use in any of the frame configurations described for "flat-shaped" HVAC filters—including frameless, rigid frame, refillable, and expandable configurations.

[0177] In some embodiments, the filter media described herein may comprise a nonwoven web with a random fiber arrangement and generally isotropic in-plane physical properties (e.g., tensile strength). Alternatively, as needed, it may have an aligned fiber structure (e.g., where the fibers are aligned in the mechanical direction, as described in U.S. Patent No. 6,858,297 by Shah et al.) and anisotropic in-plane physical properties. Some or all of the fibers constituting the nonwoven web useful for embodiments of the filter media described herein are multicomponent fibers having at least a first region and a second region, the first region may have a lower melting point than the second region. Some suitable multicomponent fibers are described, for example, in U.S. Patents No. 7,695,660, 6,057,256, 5,597,645, 5,972,808, 5,662,728 and 5,486,410, the teachings of which are incorporated herein by reference in their entirety.

[0178] Other nonwoven webs useful for the embodiments of the filter media described herein are bulky spunbond webs, such as those described in U.S. Patent No. 8,162,153 by Fox et al., the entire teachings of which are incorporated herein by reference. In other embodiments, the filter medium 60 is a low-bulk spunbond web, such as those described in U.S. Patent No. 7,947,142 by Fox et al., the entire teachings of which are incorporated herein by reference. In yet another embodiment, nonwoven webs useful for the embodiments of the filter media described herein are produced by other art or have other properties, such as the meltblown nonwoven web disclosed in U.S. Patent No. 6,858,297 by Shah et al. Other non-limiting examples of useful nonwoven web forms include bimodal fiber diameter meltblown media, such as those described in U.S. Patent No. 7,858,163, the entire teachings of which are incorporated herein by reference. Other potentially suitable media types include staple fibers, membranes, wet nonwovens, and webs manufactured from various forms of meltblown nonwovens.

[0179] The wrinkled filter media in the embodiments herein may also be useful in providing filtration for many other air movement applications, such as air conditioners, dehumidifiers, fans, circulating kitchen exhaust fans (commonly found in microwave ovens), cooling fans for electronic equipment, air supply registers, air returns, vents, and intakes. This list is not exhaustive, and it is explicitly considered that other devices providing air filtration may also benefit from the embodiments described herein.

[0180] It should also be noted that the filter media according to the embodiments herein can meet particle loading requirements with fewer sheets of filter media. In the PAPR class, this flat sheet composite media can be reduced to meet loading requirements with lower pressure loss, which can lead to smaller, lighter, and quieter units. Described herein are various filter configurations that may be used to meet capacity and pressure loss without using wrinkled media in any layer.

[0181] Predictable modifications and changes to the present invention, made without departing from the scope and spirit of the invention, will be obvious to those skilled in the art. The invention should not be limited to the embodiments described herein for illustrative purposes. In the event of any inconsistency or conflict between the description herein and any disclosure of documents incorporated herein by reference or reference, the specifications described herein shall prevail.

[0182] A filter medium is presented comprising a first layer containing a first plurality of fibers. The first plurality of fibers are characterized by an average diameter of approximately 50 microns or less, a thickness of approximately 1.7 mm or more, and a base weight of approximately 90 gsm or more. The first layer has an initial NaCl efficiency of approximately 75% or less at a face velocity of 14 cm / s. The filter medium also comprises a second layer containing a second plurality of fibers, the second plurality of fibers being characterized by an average diameter of 8 microns or more. The second layer has an initial NaCl efficiency of approximately 75% or more at a face velocity of 14 cm / s.

[0183] The filter medium may also include a third layer comprising a third set of fibers, the third set of fibers having an average diameter of approximately 8 microns or less and an initial NaCl efficiency of approximately 90% or more at a face velocity of 14 cm / s. The NaCl efficiency of the third layer is greater than that of the initial NaCl efficiency of the second layer.

[0184] The filter medium may also be characterized in that at least a portion of the third plurality of fibers is in contact with a portion of the second plurality of layers.

[0185] The filter medium may also be characterized by an initial NaCl efficiency of approximately 99% or more at a face velocity of 14 cm / s.

[0186] The filter medium may also be characterized by having an initial NaCl efficiency of approximately 98% or more at a face velocity of 14 cm / s.

[0187] The filter medium may also be characterized by having an initial NaCl efficiency of approximately 95% or more at a face velocity of 14 cm / s.

[0188] The filter medium may also be characterized by having an initial NaCl efficiency of approximately 90% or more at a face velocity of 14 cm / s.

[0189] The filter medium may also be characterized by having an initial pressure loss of approximately 9 mmH2O or less at a face velocity of 8.6 cm / s.

[0190] The filter medium may also be characterized by having an initial pressure loss of approximately 10 mmH2O or less at a face velocity of 7 cm / s.

[0191] The filter medium may also be characterized by having an initial pressure loss of approximately 20 mmH2O or less at a face velocity of 14 cm / s.

[0192] The filter medium also has a silica loading capacity of approximately 0.24 mg / (mmH2O·cm) at a face velocity of 8.6 cm / s, according to the NIOSH test method. 2 It may also be characterized as being greater than or equal to )

[0193] The filter medium also has a silica loading capacity of approximately 0.5 mg / (mmH2O·cm) at a face velocity of 7 cm / s, according to the NIOSH test method. 2 It may also be characterized as being greater than or equal to )

[0194] The filter medium also has a silica loading capacity of approximately 0.3 mg / (mmH2O·cm) at a face velocity of 14 cm / s, according to the NIOSH test method. 2 It may also be characterized as being greater than or equal to )

[0195] The filter medium may also be characterized in that the first layer includes a wrinkled medium.

[0196] The filter medium may also be characterized in that the first layer includes a film.

[0197] The filter medium may also be characterized in that the first layer contains an adsorbent.

[0198] The filter medium may also be characterized in that the first layer contains meltblown fibers.

[0199] The filter medium may also be characterized by having a layer that includes a fibrillated film.

[0200] The filter medium may also be characterized in that the first layer contains spunbond fibers.

[0201] The filter medium may also be characterized in that the first layer includes fibers having an effective diameter of less than 40 μm.

[0202] The filter medium may also be characterized in that the first layer contains fibers having an effective diameter of less than 20 μm.

[0203] The filter medium may also be characterized in that the first layer includes fibers having an effective diameter of less than 15 μm.

[0204] The filter medium may also be characterized in that the first layer includes fibers having an effective diameter of less than 10 μm.

[0205] The filter medium may also be characterized in that the first layer includes fibers having a non-circular cross-sectional area.

[0206] The filter medium may also be characterized in that the first layer comprises a bulky nonwoven porous fiber web.

[0207] The filter medium may also be characterized in that the first layer includes a film.

[0208] The filter medium may also be characterized by being formed in a respirator.

[0209] The filter medium may also be characterized by the respirator being a disposable respirator, a reusable respirator, a disposable-reusable hybrid respirator, or a PAPR.

[0210] The filter medium may also be characterized in that one of the first and second layers includes a wrinkled medium.

[0211] The filter medium may also be characterized by the first or second layer comprising a film.

[0212] The filter medium may also be characterized by having a wrinkled film.

[0213] The filter medium may also be characterized by being formed for use as an air conditioning filter.

[0214] The filter medium may also be characterized by being formed for use as a furnace filter.

[0215] The filter medium may also be characterized by being formed for personal air purifiers.

[0216] A filter medium is presented comprising a first layer containing a first nonwoven material and a second layer containing a second nonwoven material. One of the first or second layers comprises a wrinkled medium. The wrinkled medium comprises a nonwoven sheet comprising a first series of elastic filaments substantially parallel and not bonded between the first and second nonwoven porous fiber webs. The first nonwoven porous fiber web is directly bonded to the second nonwoven porous fiber web. At least a portion of the pleated filter medium is elastically stretchable under tension.

[0217] The filter medium may also include a third layer adjacent to the first layer on the first side and adjacent to the second layer on the second side, characterized in that the air passing through the filter passes through the first layer, then the third layer, and then the second layer.

[0218] The filter medium may also be characterized in that the first layer is a high-load capacitance layer.

[0219] The filter medium may also be characterized by having a second layer that is a high-efficiency layer.

[0220] The filter medium may also be characterized in that the first layer includes a wrinkled medium.

[0221] The filter medium may also be characterized in that the wrinkled medium is a first wrinkled medium. The second layer includes a second wrinkled medium, the first wrinkled medium differing from the second wrinkled medium in any of the following: fiber type, fiber thickness, elastic filament type, or spacing between adjacent elastic filaments.

[0222] The filter medium may also be characterized in that the first nonwoven porous fiber web contains meltblown fibers.

[0223] The filter medium may also be characterized in that the first nonwoven porous fiber web includes a fibrillated film.

[0224] The filter medium may also be characterized in that the first nonwoven porous fiber web contains spunbond fibers.

[0225] The filter medium may also be characterized in that the first nonwoven porous fiber web contains fibers having a diameter of less than 40 μm.

[0226] The filter medium may also be characterized in that the first nonwoven porous fiber web contains fibers having a diameter of less than 20 μm.

[0227] The filter medium may also be characterized in that the first nonwoven porous fiber web contains fibers having a diameter of less than 15 μm.

[0228] The filter medium may also be characterized in that the first nonwoven porous fiber web contains fibers having a diameter of less than 10 μm.

[0229] The filter medium may also be characterized in that the first nonwoven porous fiber web is a bulky nonwoven porous fiber web.

[0230] The filter medium may also be characterized in that the nonwoven sheet is a first nonwoven sheet. The first layer includes a second nonwoven sheet.

[0231] The filter medium may also be characterized in that the second nonwoven sheet and the first nonwoven sheet contain the same medium.

[0232] The filter medium may also be characterized in that the filter is formed on a disposable respirator.

[0233] The filter medium may also be characterized by the fact that the filter is formed for use in PAPR.

[0234] A filter for a breathing device is presented, comprising a high-load capacity layer configured to adsorb the majority of particles to be filtered by the filter. The filter also comprises a high-efficiency layer configured to adsorb a high proportion of particles in the airflow passing through the high-efficiency layer. The filter is configured such that, when worn by a user, air passes through the high-load capacity layer before passing through the high-efficiency layer. Either the high-load capacity layer or the high-efficiency layer comprises a wrinkled medium.

[0235] The filter may also be characterized by including a film in the high-load capacity layer or the high-efficiency layer.

[0236] The filter may also be characterized by having a wrinkled film.

[0237] The filter may also be characterized in that the high-load capacity layer includes a wrinkled medium. The wrinkled medium includes a bulky nonwoven medium.

[0238] The filter may also be characterized in that the high-efficiency layer contains a wrinkled medium.

[0239] The filter may also be characterized in that the high-load capacity layer includes a first wrinkled medium, and the high-efficiency layer includes a second wrinkled medium, wherein the first wrinkled medium is different from the second wrinkled medium.

[0240] The filter may also be characterized in that the high-load capacity layer includes a deep-load medium.

[0241] The filter may also be characterized in that the high-efficiency layer contains a surface loading medium.

[0242] The filter may also be characterized by the inclusion of melt-blown fibers in the high-load capacity layer or high-efficiency layer.

[0243] The filter may also be characterized by including a high-load capacity layer or a high-efficiency layer.

[0244] The filter may also be characterized by the inclusion of spunbond fibers in the high-load capacity layer or high-efficiency layer.

[0245] The filter may also be characterized in that the high-load capacity layer or high-efficiency layer contains fibers having a diameter of less than 40 μm.

[0246] The filter may also be characterized by the inclusion of a high-load capacity layer or a high-efficiency layer containing fibers having a diameter of less than 20 μm.

[0247] The filter may also be characterized by the inclusion of a high-load capacity layer or a high-efficiency layer containing fibers having a diameter of less than 15 μm.

[0248] The filter may also be characterized in that the high-load capacity layer or high-efficiency layer contains fibers having a diameter of less than 10 μm.

[0249] The filter may also be characterized by the respirator being a disposable respirator.

[0250] The filter may also be characterized by being molded into a cup shape.

[0251] The filter may also be characterized by being formed in a vertically folding or horizontally folding disposable respirator.

[0252] The filter may also be characterized by the respirator being an electrically operated air-purifying respirator (PAPR).

[0253] The filter may also be characterized by being shaped so that the respirator fits within the PAPR housing.

[0254] The filter may also be characterized in that the high load capacity layer has a first thickness and the high efficiency layer has a second thickness. The first and second thicknesses are different.

[0255] The filter may also be characterized in that the high load capacity layer is composed of a first wrinkled media sheet and a second wrinkled media sheet.

[0256] The filter may also be characterized in that the high efficiency layer is composed of a first wrinkled media sheet and a second wrinkled media sheet.

[0257] The filter may also include a transition layer between the first layer and the second layer, and the air passing through the filter passes through the first layer before passing through the transition layer.

[0258] A method of forming a respiratory filter medium is presented. The method includes forming a high load capacity zone, where the high load capacity zone includes a first non-woven medium, forming a high efficiency zone, where the high efficiency zone includes a second non-woven medium, and sealing the high load capacity zone and the high efficiency zone to form a respiratory filter. Either the first or the second non-woven medium includes a wrinkled medium.

[0259] This method may further be implemented such that the high load capacity zone or the high efficiency zone includes a membrane.

[0260] This method may further be implemented such that the membrane is wrinkled.

[0261] This method may further be implemented such that the first non-woven medium includes a first sheet of wrinkled medium and a second sheet of wrinkled medium.

[0262] This method may further be implemented such that the second non-woven medium includes a third sheet of wrinkled medium and a fourth sheet of wrinkled medium.

[0263] This method may further be carried out such that the first nonwoven medium is selected for deep loading of particles.

[0264] This method may further be carried out such that a second nonwoven medium is selected for surface loading of the particles.

[0265] This method may further be implemented such that sealing includes sealing high-load capacity zones separately from high-efficiency zones.

[0266] This method may further be carried out such that sealing involves simultaneously sealing the second nonwoven material and the first nonwoven material.

[0267] This method may further be carried out so that sealing also involves die-cutting.

[0268] This method may further be carried out so that sealing includes the application of adhesive.

[0269] This method may further be carried out so that sealing includes welding.

[0270] This method may also be implemented so that sealing includes sewing.

[0271] This method may further be implemented to include placing the filter medium in the housing.

[0272] This method may further be carried out such that the first nonwoven medium includes a first wrinkled medium and the second nonwoven medium includes a second wrinkled medium. The first wrinkled medium differs from the second wrinkled medium in one of the following: fiber type, fiber thickness, elastic filament type, or spacing between adjacent elastic filaments.

[0273] This method may further be implemented to include forming a transition zone. The transition zone includes a third non-woven medium. Sealing includes sealing the high load capacity zone and the high efficiency zone such that when air flows through the breathing filter, air passes through the high load capacity zone before the transition zone and the high efficiency zone.

[0274] This method may further be implemented such that at least two of the high efficiency zone, the high load capacity zone, and the transition zone include a wrinkled medium.

[0275] This method may further be implemented such that each of the high efficiency zone, the high load capacity zone, and the transition zone includes a wrinkled medium.

[0276] This method may further be implemented such that the high load capacity layer includes a deep load medium.

[0277] This method may further be implemented such that the high efficiency layer includes a surface load medium.

[0278] This method may further be implemented such that the high load capacity layer or the high efficiency layer includes melt blown fibers.

[0279] This method may further be implemented such that the high load capacity layer or the high efficiency layer includes fibrillated film fibers.

[0280] This method may further be implemented such that the high load capacity layer or the high efficiency layer includes spunbond fibers.

[0281] This method may further be implemented such that the high load capacity layer or the high efficiency layer includes fibers having a diameter of less than 40 μm.

[0282] This method may further be implemented such that the high load capacity layer or the high efficiency layer includes fibers having a diameter of less than 20 μm.

[0283] This method may further be carried out so that the high-load capacity layer or high-efficiency layer includes fibers having a diameter of less than 15 μm.

[0284] This method may further be carried out so that the high-load capacity layer or high-efficiency layer includes fibers having a diameter of less than 10 μm.

[0285] This method may also be implemented so that the respirator is a disposable respirator.

[0286] This method may also be carried out so that the filter is formed into a cup shape.

[0287] This method may further be implemented so that the filter is formed into a vertically folding or horizontally folding disposable respirator.

[0288] This method may also be implemented such that the respirator is an electrically operated air-purifying respirator (PAPR).

[0289] A filter medium is presented that includes a first layer containing a first plurality of fibers. The first plurality of fibers have an average diameter of approximately 50 microns or less, a thickness of approximately 1.0 mm or more, and a base weight of approximately 30 gsm or more. The first layer has an initial NaCl efficiency of approximately 50% or less at a face velocity of 14 cm / s. The second layer includes a second plurality of fibers, the second plurality of fibers having an average diameter of 8 microns or more. The second layer has an initial NaCl efficiency of approximately 50% or more at a face velocity of 14 cm / s.

[0290] The filter medium may be implemented to include a third layer containing a third plurality of fibers, the third plurality of fibers having an average diameter of about 8 microns or less, a face velocity of 14 cm / s, and an initial NaCl efficiency of about 65% or more, and the NaCl efficiency of the third layer is greater than the initial NaCl efficiency of the second layer.

[0291] The filter medium may be implemented such that at least a portion of the third plurality of fibers is in contact with a portion of the second plurality of layers.

[0292] The filter medium may be prepared such that the initial NaCl efficiency is approximately 95% or higher at a face velocity of 14 cm / s.

[0293] The filter medium may be prepared at a face velocity of 14 cm / s such that the initial NaCl efficiency of the filter medium is approximately 90% or higher.

[0294] The filter medium may be prepared at a face velocity of 14 cm / s such that the initial NaCl efficiency of the filter medium is approximately 75% or higher.

[0295] The filter medium may be prepared so that the initial NaCl efficiency of the filter medium is approximately 50% or more at a face velocity of 14 cm / s.

[0296] The filter medium may be prepared such that the initial pressure loss of the filter medium is approximately 2.0 mmH2O or less at a face velocity of 14 cm / s.

[0297] The filter medium may be constructed such that the first layer includes a wrinkled medium.

[0298] The filter medium may be constructed such that the first layer contains an adsorbent.

[0299] The filter medium may be constructed such that the first layer contains meltblown fibers.

[0300] The filter medium may be constructed such that the layer includes a fibrillated film.

[0301] The filter medium may be constructed such that the first layer contains spunbond fibers.

[0302] The filter medium may be implemented such that the first layer contains fibers of discrete lengths.

[0303] The filter medium may be constructed such that the first layer includes fibers having an effective diameter of less than 50 μm.

[0304] The filter medium may be constructed such that the fibers in the first layer have an effective diameter of less than 35 μm.

[0305] The filter medium may be constructed such that the first layer includes fibers having an effective diameter of less than 25 μm.

[0306] The filter medium may be constructed such that the first layer includes fibers having an effective diameter of less than 20 μm.

[0307] The filter medium may be implemented such that the first layer includes fibers having a non-circular cross-sectional area.

[0308] The filter medium may be constructed such that the first layer includes a bulky nonwoven porous fiber web.

[0309] The filter medium may be constructed such that one of the first and second layers includes a wrinkled medium.

[0310] The filter medium may be constructed to be formed for use in an air conditioning system.

[0311] The filter medium may be constructed to be formed for use in heating, ventilation, and / or air conditioning systems.

[0312] The filter medium may be manufactured to be formed for use in a portable air purifier.

[0313] The filter medium may be manufactured to be formed for use in a portable fan.

[0314] A filter medium is presented comprising a first layer containing a first nonwoven material and a second layer containing a second nonwoven material. One of the first or second layers comprises a wrinkled medium. The wrinkled medium comprises a nonwoven sheet comprising a first series of elastic filaments substantially parallel and not bonded between the first and second nonwoven porous fiber webs. The first nonwoven porous fiber web is directly bonded to the second nonwoven porous fiber web. At least a portion of the pleated filter medium is elastically stretchable under tension.

[0315] The filter medium may include a third layer adjacent to the first layer on the first side and adjacent to the second layer on the second side, and the air flowing through the filter may flow through the first layer, then the third layer, and then the second layer.

[0316] The filter medium may be configured such that the first layer is a high-load capacity layer.

[0317] The filter medium may be configured such that the second layer is a high-efficiency layer.

[0318] The filter medium may be constructed such that the first layer includes a wrinkled medium.

[0319] The filter medium may be configured such that the wrinkled medium is a first wrinkled medium, and the second layer includes a second wrinkled medium, wherein the first wrinkled medium differs from the second wrinkled medium in one of the following: fiber type, fiber thickness, elastic filament type, or spacing between adjacent elastic filaments.

[0320] The filter medium may be constructed such that the first nonwoven porous fiber web contains meltblown fibers.

[0321] The filter medium may be constructed such that the first nonwoven porous fiber web includes a fibrillated film.

[0322] The filter medium may be constructed such that the first nonwoven porous fiber web contains spunbond fibers.

[0323] The filter medium may be constructed such that the first nonwoven porous fiber web contains fibers of discrete lengths.

[0324] The filter medium may be constructed such that the first nonwoven porous fiber web contains fibers having a diameter of less than 50 μm.

[0325] The filter medium may be constructed such that the first nonwoven porous fiber web contains fibers having a diameter of less than 35 μm.

[0326] The filter medium may be constructed such that the first nonwoven porous fiber web contains fibers having a diameter of less than 25 μm.

[0327] The filter medium may be constructed such that the first nonwoven porous fiber web contains fibers having a diameter of less than 20 μm.

[0328] The filter medium may be implemented such that the first nonwoven porous fiber web is a bulky nonwoven porous fiber web.

[0329] The filter medium may be constructed such that the nonwoven sheet is a first nonwoven sheet, and the first layer includes a second nonwoven sheet.

[0330] The filter medium may be constructed such that the second nonwoven sheet and the first nonwoven sheet contain the same medium.

[0331] The filter medium may be constructed to be formed for use in heating, ventilation, and / or air conditioning systems.

[0332] The filter medium may be constructed to be formed for use in an air conditioning system.

[0333] The filter medium may be manufactured to be formed for use in a portable air purifier.

[0334] The filter medium may be manufactured to be formed for use in a portable fan.

[0335] A filter for an air treatment device is presented, comprising a high-load capacity layer configured to adsorb the majority of particles to be filtered by the filter, and a high-efficiency layer configured to adsorb a high proportion of particles in the airflow passing through the high-efficiency layer. The filter is configured, in use, so that air passes through the high-load capacity layer before passing through the high-efficiency layer. Either the high-load capacity layer or the high-efficiency layer contains a wrinkled medium.

[0336] The filter may be constructed such that the high-load capacity layer contains a wrinkled medium, and the wrinkled medium contains a bulky nonwoven medium.

[0337] The filter may be implemented such that the high-efficiency layer includes a wrinkled medium.

[0338] The filter may be constructed such that the high-load capacity layer includes a first wrinkled medium, and the high-efficiency layer includes a second wrinkled medium, and the first wrinkled medium is different from the second wrinkled medium.

[0339] The filter may be implemented such that the high-load capacity layer includes a deep-load medium.

[0340] The filter may be constructed such that the high-efficiency layer includes a surface loading medium.

[0341] The filter may be constructed such that the high-load capacity layer or high-efficiency layer contains melt-blown fibers.

[0342] The filter may be implemented to include a high-load capacity layer or a high-efficiency layer.

[0343] The filter may be constructed such that the high-load capacity layer or the high-efficiency layer contains spunbond fibers.

[0344] The filter may be implemented such that the high-load capacity layer or the high-efficiency layer includes fibers of discrete lengths.

[0345] The filter may be constructed such that the high-load capacity layer or the high-efficiency layer includes fibers having a diameter of less than 50 μm.

[0346] The filter may be constructed such that the high-load capacity layer or the high-efficiency layer includes fibers having a diameter of less than 35 μm.

[0347] The filter may be constructed such that the high-load capacity layer or the high-efficiency layer includes fibers with a diameter of less than 25 μm.

[0348] The filter may be constructed such that the high-load capacity layer or the high-efficiency layer includes fibers having a diameter of less than 20 μm.

[0349] The filter may be constructed such that the high-load capacity layer has a first thickness, the high-efficiency layer has a second thickness, and the first and second thicknesses are different.

[0350] The filter may be implemented such that the high-load capacity layer consists of a first sheet of wrinkled media and a second sheet of wrinkled media.

[0351] The filter may be implemented such that the high-efficiency layer consists of a first sheet of wrinkled media and a second sheet of wrinkled media.

[0352] The filter may include a transition layer between the first and second layers, such that the air passing through the filter passes through the first layer before passing through the transition layer.

[0353] This method may be implemented such that the filter is a filter for heating, ventilation, and / or air conditioning equipment.

[0354] This method may be implemented such that the filter is a filter for an air conditioning system.

[0355] This method may be implemented such that the filter is the filter of a portable air purifier.

[0356] This method may be implemented such that the filter is a filter for a portable fan.

[0357] A method for forming a filter medium is presented, which includes forming a high-load capacity zone, the high-load capacity zone comprising a first nonwoven medium, forming a high-efficiency zone, the high-efficiency zone comprising a second nonwoven medium, and combining the high-load capacity zone and the high-efficiency zone to form a filter medium. One of the first and second nonwoven mediums comprises a wrinkled medium.

[0358] This method may be carried out such that the first nonwoven medium includes a first sheet of wrinkled medium and a second sheet of wrinkled medium.

[0359] This method may be carried out such that the second nonwoven medium includes a third sheet of wrinkled medium and a fourth sheet of wrinkled medium.

[0360] This method may be carried out such that the first nonwoven medium is selected for deep loading of particles.

[0361] This method may be carried out such that a second nonwoven medium is selected for surface loading of particles.

[0362] This method may be implemented such that the coupling includes coupling high-load capacity zones separately from high-efficiency zones.

[0363] This method may be carried out such that the bonding involves simultaneously bonding the second nonwoven medium and the first nonwoven medium.

[0364] This method may be carried out such that joining includes die-cutting.

[0365] This method may be carried out such that the bonding involves the application of an adhesive.

[0366] This method may be carried out such that joining includes welding.

[0367] This method may be carried out so that the joining includes sewing.

[0368] This method may be implemented to include placing the filter medium within a housing or frame.

[0369] This method may be carried out such that the first nonwoven medium includes a first wrinkled medium, the second nonwoven medium includes a second wrinkled medium, and the first wrinkled medium differs from the second wrinkled medium in one of the following: fiber type, fiber thickness, elastic filament type, or spacing between adjacent elastic filaments.

[0370] This method may be implemented by including forming a transition zone, the transition zone comprising a third nonwoven medium, and the bonding of a high-load capacity zone and a high-efficiency zone, so that when air flows through the breathing filter, it passes through the high-load capacity zone before the transition zone and the high-efficiency zone.

[0371] This method may be implemented such that at least two of the high-efficiency zone, high-load capacity zone, and transition zone include wrinkled media.

[0372] This method may be implemented such that the high-efficiency zone, the high-load capacity zone, and the transition zone each contain a wrinkled medium.

[0373] This method may be implemented such that the high-load capacity layer includes a deep-load medium.

[0374] This method may be carried out such that the high-efficiency layer includes a surface loading medium.

[0375] This method may be carried out such that the high-load capacity layer or high-efficiency layer contains meltblown fibers.

[0376] This method may be carried out such that the high-load capacity layer or high-efficiency layer includes fibrillated film fibers.

[0377] This method may be carried out such that the high-load capacity layer or high-efficiency layer includes spunbond fibers.

[0378] This method may be carried out such that the high-load capacity layer or high-efficiency layer includes fibers of discrete lengths.

[0379] This method may be carried out such that the high-load capacity layer or high-efficiency layer includes fibers having a diameter of less than 50 μm.

[0380] This method may be carried out such that the high-load capacity layer or high-efficiency layer includes fibers having a diameter of less than 35 μm.

[0381] This method may be carried out such that the high-load capacity layer or high-efficiency layer includes fibers having a diameter of less than 25 μm.

[0382] This method may be carried out such that the high-load capacity layer or high-efficiency layer includes fibers having a diameter of less than 20 μm.

[0383] This method may be implemented so that the filter medium is formed for use in heating, ventilation, and / or air conditioning systems.

[0384] This method may be carried out so that the filter medium is formed for use in an air conditioning system.

[0385] This method may be carried out so that the filter medium is formed for use in a portable air purifier.

[0386] This method may be implemented so that the filter medium is formed for use in a portable fan. <Comparative Examples 1-4 (CE1 to CE4) and Example 1 (EX1)>

[0387] Sample creation method 1 was used to create CE1-4 and EX1, which consist of various web layers listed in Table 3.

[0388] Table 5 shows the silica loading test at a flow rate of 74 LPM, i.e., a face velocity of approximately 8.6 cm / s, at 144 cm². 2 The test results for the media samples are shown. The initial pressure drop (or dP) was measured before silica loading, and the final pressure drop was measured after silica loading. The silica LQF of EX1 is significantly higher than that of CE1 to CE4. [Table 5] <Comparative Examples 5-6 (CE5 to CE6) and Examples 2-4 (EX2 to EX4)>

[0389] Sample creation method 1 was used to create CE5-6 and EX2-4, which consist of various web layers listed in Table 3.

[0390] Table 6 shows the silica loading test at a flow rate of 43 LPM, i.e., a face velocity of approximately 7 cm / s, at 102 cm². 2 The test results for the media samples are shown. The initial pressure drop of the media was measured before silica loading, and the final pressure drop was measured after silica loading. The silica LQF of EX2 to EX4 is significantly higher than that of CE5 and CE6. [Table 6]

[0391] Two pleated media packs used in PAPR were subjected to silica load testing as comparative examples CE7 and CE8. The pleated packs were made with glass fiber media HB6643, available from Hollingsworth & Vose (112 Washington Street East Walpole, MA 02032 USA). The dimensions of the pleated packs, test conditions, and test results are listed in Table 7. Even though the test surface velocity of the pleated packs was much lower than that of the media samples mentioned above, the LQF of CE7 and CE8 was much lower than that of EX2-4. [Table 7] <Comparative Example 9 (CE9) and Examples 5-9 (EX5 to EX9)>

[0392] Sample creation methods 1, 2, and 3 were used to create CE9 and EX5-9, which consist of the various web layers listed in Tables 3 and 4.

[0393] Table 8 shows the silica loading test at a flow rate of 85 LPM, i.e., a face velocity of approximately 14 cm / s on a flat sheet, at 102 cm². 2 The test results for the media samples are shown. The initial pressure drop of the media was measured before silica loading, and the final pressure drop was measured after silica loading. The LQF of EX5 and EX6, using wrinkled media, was much higher. [Table 8] <Comparative Examples 10-12 (CE10 to CE12) and Examples 10-11 (EX10 to EX12)>

[0394] Sample creation methods 1 and 2 were used to create CE10 and EX4-8, which consist of various web layers listed in Table 3.

[0395] Table 9 shows the results of a welding fume particle loading test at a flow rate of 66 LPM, i.e., a face velocity of approximately 14 cm / s, for a total of 78.5 cm 2The test results for the medium sample are shown. Pressure drop delta is the increase in pressure drop after loading the medium with approximately 150 mg of welding fume particles. [Table 9] <Comparative Examples 13-14 (CE13 to CE14) and Examples 13-14 (EX13 to EX14)>

[0396] Sample creation methods 1 and 3 were used to create CE13-14 and EX13-14, which consist of the various web layers listed in Tables 3 and 4.

[0397] Table 10 shows the results of the NaCl loading test at a flow rate of 85 LPM, i.e., a face velocity of approximately 13.9 cm / s, at 102 cm². 2 The test results for the medium sample are shown. The initial pressure drop of the medium was measured before NaCl loading, and the final pressure drop was measured after loading. [Table 10] <Comparative Example 15 (CE15) and Example 15 (EX15)>

[0398] Sample creation method 4 was used to create CE15 and EX15, which consist of the various web layers listed in Tables 3 and 4.

[0399] Table 11 shows the test results for respirator samples in an NaCl loading test at a flow rate of 85 LPM, i.e., a face velocity of approximately 13.9 cm / s. The initial pressure drop was measured before NaCl loading, and the final pressure drop was measured after loading.

[0400] Note: For ease of comparison, the LQF of NaCl here is based on the total area of ​​the respirator, not per unit surface area. [Table 11]

Claims

1. A filter medium comprising a first layer and a second layer, The first layer comprises a first plurality of fibers, The first plurality of fibers, An average diameter of approximately 50 microns or less, A thickness of approximately 1.7 mm or more, Having a base weight of approximately 90 gsm or more, The first layer has an initial NaCl efficiency of approximately 75% or less at a surface velocity of 14 cm / s. The second layer comprises a second plurality of fibers, The aforementioned second plurality of fibers, Having an average diameter of 8 microns or more, The second layer has an initial NaCl efficiency of approximately 75% or more at a surface velocity of 14 cm / s. Filter medium.

2. Further comprising a third layer, wherein the third layer comprises a third plurality of fibers, The aforementioned third plurality of fibers, Having an average diameter of approximately 8 microns or less, It has an initial NaCl efficiency of over 90% at a surface velocity of 14 cm / s. The NaCl efficiency of the third layer is greater than the initial NaCl efficiency of the second layer. At least a portion of the third plurality of fibers is in contact with a portion of the second plurality of layers. The filter medium according to claim 1.

3. The filter medium according to claim 1 or 2, wherein the initial NaCl efficiency of the filter medium is about 90% or more at a face velocity of 14 cm / s.

4. The filter medium according to any one of claims 1 to 3, wherein the silica loading capacity of the filter medium according to the NIOSH test method is approximately 0.24 mg / (mmH2O・cm2) or more at a face velocity of 8.6 cm / s.

5. The filter medium according to any one of claims 1 to 4, wherein the first layer comprises fibers having an effective diameter of less than 40 μm.

6. The filter medium according to any one of claims 1 to 5, wherein the first layer includes fibers having a non-circular cross-sectional area.

7. The filter medium according to any one of claims 1 to 6, wherein the filter medium is formed in the respiratory tract.

8. The filter medium according to any one of claims 1 to 7, wherein one of the first layer and the second layer includes a wrinkled medium.

9. The filter medium according to any one of claims 1 to 8, wherein the first layer or the second layer includes a film.

10. The filter medium according to claim 9, wherein the aforementioned membrane is a wrinkled membrane.

11. The filter medium according to any one of claims 1 to 10, wherein the filter medium is formed for use as an air conditioning filter, a furnace filter, or a personal air purifier.

12. A filter medium comprising a first layer containing a first nonwoven fabric material and a second layer containing a second nonwoven fabric material, wherein either the first layer or the second layer contains a wrinkled medium. The aforementioned wrinkled medium The nonwoven fabric sheet includes a first series of elastic filaments that are substantially parallel and not bonded between a first nonwoven porous fiber web and a second nonwoven porous fiber web, The first nonwoven porous fiber web is directly bonded to the second nonwoven porous fiber web, A filter medium in which at least a portion of the pleated filter medium is elastically stretchable under tension.

13. The filter medium according to claim 12, further comprising a third layer adjacent to the first layer on a first side and adjacent to the second layer on a second side, wherein the air passing through the filter passes through the first layer, then the third layer, then the second layer.

14. The filter medium according to claim 12 or 13, wherein the first layer is a high-load capacity layer.

15. The filter medium according to claim 13 or 14, wherein the second layer is a high-efficiency layer.

16. The filter medium according to claim 13, wherein the wrinkled medium is a first wrinkled medium, the second layer comprises a second wrinkled medium, and the first wrinkled medium differs from the second wrinkled medium in any of the following: the type of fiber, the thickness of the fiber, the type of elastic filament, or the spacing between adjacent elastic filaments.

17. The filter medium according to any one of claims 12 to 16, wherein the first nonwoven porous fiber web includes fibers having a diameter of less than 40 μm.

18. The filter medium according to any one of claims 12 to 17, wherein the filter is formed for use in PAPR.

19. A filter for a respiratory device, wherein the filter is A high-load capacity layer configured to adsorb most of the particles filtered by the aforementioned filter, It includes a high-efficiency layer configured to adsorb a high proportion of particles in the airflow passing through the high-efficiency layer, The filter is configured such that when worn by the user, air passes through the high-capacity layer before passing through the high-efficiency layer. One of the high-load capacity layer or the high-efficiency layer includes a wrinkled medium, filter.

20. The filter according to claim 19, wherein the high load capacity layer or the high efficiency layer includes a film.

21. The filter according to claim 20, wherein the aforementioned membrane is wrinkled.

22. The filter according to any one of claims 19 to 21, wherein the high load capacity layer includes a wrinkled medium, and the wrinkled medium includes a bulky nonwoven fabric medium.

23. The filter according to any one of claims 20 to 22, wherein the high load capacity layer includes a first wrinkled medium, and the high efficiency layer includes a second wrinkled medium, and the first wrinkled medium is different from the second wrinkled medium.

24. The filter according to any one of claims 19 to 23, wherein the high load capacity layer or the high efficiency layer includes fibers having a diameter of less than 40 μm.

25. The filter according to any one of claims 19 to 24, wherein the respirator is a disposable respirator and the filter is molded into a cup shape.

26. The filter according to any one of claims 19 to 25, wherein the respirator is a disposable respirator and the filter is formed in a vertically foldable or horizontally foldable disposable respirator.

27. The filter according to any one of claims 19 to 26, wherein the high-load capacity layer has a first thickness, and the high-efficiency layer has a second thickness, and the first thickness and the second thickness are different.

28. The filter according to any one of claims 19 to 27, further comprising a transition layer between the first layer and the second layer, wherein the air passing through the filter passes through the first layer before passing through the transition layer.

29. A method for forming a respiratory filter medium, wherein the method is To form a high-load capacity zone containing a first nonwoven fabric medium, To form a high-efficiency zone containing a second nonwoven fabric medium, This includes sealing the high-load capacity zone and the high-efficiency zone to form a respiratory filter, The first nonwoven fabric medium and the second nonwoven fabric medium include a wrinkled medium, method.

30. The method according to claim 29, wherein the first nonwoven medium comprises a first sheet of a wrinkled medium and a second sheet of a wrinkled medium.

31. The method according to claim 29 or 30, wherein the second nonwoven medium includes a third sheet of wrinkled medium and a fourth sheet of wrinkled medium.

32. The method according to any one of claims 29 to 31, wherein sealing includes sealing the high-load capacity zone separately from the high-efficiency zone.

33. The method according to any one of claims 29 to 32, wherein sealing includes simultaneously sealing a second nonwoven fabric medium and a first nonwoven fabric medium.

34. The method according to any one of claims 29 to 33, wherein sealing includes die-cutting, adhesive application, welding, or sewing.

35. The method according to any one of claims 29 to 34, further comprising placing a filter medium in a housing.

36. The method according to any one of claims 29 to 35, wherein the first nonwoven medium comprises a first wrinkled medium, the second nonwoven medium comprises a second wrinkled medium, and the first wrinkled medium differs from the second wrinkled medium in any of the following: the type of fiber, the thickness of the fiber, the type of elastic filament, or the spacing between adjacent elastic filaments.

37. The method according to any one of claims 29 to 36, further comprising forming a transition zone, the transition zone comprising a third nonwoven fabric medium, and sealing the high load capacity zone and the high efficiency zone such that air passing through the breathing filter passes through the high load capacity zone before the transition zone and the high efficiency zone.

38. The method according to claim 37, wherein at least two of the high-efficiency zone, the high-load capacity zone, and the transition zone include a wrinkled medium.

39. The method according to claim 37, wherein each of the high-efficiency zone, the high-load capacity zone, and the transition zone includes a wrinkled medium.

40. The method according to any one of claims 29 to 39, wherein the high load capacity layer or the high efficiency layer includes fibers having a diameter of less than 20 μm.

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