Filter media, composite materials, and mask systems using the same

Abstract

The present disclosure describes filtration media and facemask filters and facemask systems including those filtration media. In one aspect, the filtration media includes a fibrous media including a multi-component binder fiber, a glass fiber, and a microfibrillated cellulose fiber. In some aspects, the fibrous media further includes a PET fiber. In another aspect, the filtration media includes an electrostatically charged filtration media, a fine fiber layer, and a scrim. In yet another aspect, the filtration media includes two fine fiber layers and two scrims. In further aspects, the filtration media includes a bicomponent fiber, a polyethylene terephthalate fiber, and a microfibrillated cellulose fiber. In another aspect, the filtration media includes a support layer, a continuous fine fiber layer, and an efficiency layer. Combinations and composites of filtration media are also contemplated.

Description

[0001] Cross-reference of related applications

[0002] This application claims U.S. Provisional Application No. 63 / 004,464, filed April 2, 2020; U.S. Provisional Application No. 63 / 004,621, filed April 3, 2020; U.S. Provisional Application No. 63 / 004,926, filed April 3, 2020; U.S. Provisional Application No. 63 / 004,939, filed April 3, 2020; and U.S. Provisional Application No. 63 / 004,954, filed April 3, 2020. The interests in U.S. Provisional Application No. 63 / 024,894, filed May 14, 2020; U.S. Provisional Application No. 63 / 042,943, filed June 23, 2020; U.S. Provisional Application No. 63 / 081,143, filed September 21, 2020; and U.S. Provisional Application No. 63 / 081,159, filed September 21, 2020, the disclosures of each of these applications are incorporated herein by reference in their entirety. Background Technology

[0003] Face mask filters, including those for face shields, are designed to significantly reduce or prevent the transmission of liquid and / or airborne contaminants from the ambient atmosphere to the wearer. In a medical setting, liquid sources may include respiratory droplets (e.g., mucus), bodily fluids (e.g., sweat), saline solutions, etc. Examples of potential airborne contaminants include, for example, biological contaminants such as bacteria, viruses, fungal spores, etc. Summary of the Invention

[0004] This disclosure describes filter media, composite materials including filter media, and face mask filters including those filter media.

[0005] As used herein, “fine fiber” refers to a fiber having a diameter of at most 10 micrometers (µm). In some embodiments, the diameter of the fine fiber is at least 50 nm or at least 100 nm.

[0006] As used in this article, micron is equivalent to micrometer (μm).

[0007] As used herein, a “fiber” has an average fiber diameter of up to 100 micrometers. As used herein, a fiber with an “average” diameter indicates, in a sample of multiple fibers, the average fiber diameter of a fiber group in that sample has the average fiber diameter shown. A fiber group includes fibers having a diameter within 25% of the average fiber diameter. For example, a fiber group with an average diameter of 1000 nm includes fibers with a diameter of at least 750 nm and up to 1250 nm. In another example, a fiber group with an average diameter of 250 nm includes fibers with a diameter of at least 188 nm and up to 313 nm. In another example, a fiber group with an average diameter of 500 nm includes fibers with a diameter of at least 375 nm and up to 625 nm. In yet another example, a fiber group with an average diameter of 1400 nm includes fibers with a diameter of at least 1050 nm and up to 1750 nm. Furthermore, as used herein, a “fiber” has an aspect ratio (i.e., the ratio of length to transverse dimension) greater than 3:1 and preferably greater than 5:1. For example, glass fibers can have an aspect ratio greater than 100:1. In this context, "transverse dimension" refers to the width (two-dimensional) or diameter (three-dimensional) of the fiber. The term "diameter" refers to the diameter of the circular cross-section of the fiber, or the maximum cross-sectional dimension of the non-circular cross-section of the fiber. Depending on the desired outcome, the fiber length can be finite or infinite.

[0008] Fiber diameter can be measured using top-down SEM images. The sample can be sputter-coated. A useful sputter coater can be a mixture of gold and palladium, including, for example, an Au:Pd 60:40 mixture. More accurate fiber diameter measurements can be obtained by measuring the fiber diameter at at least 30 locations in the sample. Software such as Trainable WekaSegmentation (an ImageJ plugin) can be used to analyze fiber diameter.

[0009] A “face mask filter” is defined as a filter element configured to filter air flowing toward a face container defined by a face mask. A face mask filter may form at least part of the face mask itself, or it may be a filter element that is separate from or away from the face mask and configured to be in fluid communication with the face container defined by the face mask.

[0010] "Face mask" is defined herein as a component configured to extend across at least a portion of a wearer's face. Face masks typically define a face container configured to receive at least a portion of the wearer's face.

[0011] A “mask system” is defined as a system incorporating a mask. A “mask system” can include a single mask or a mask combined with a mask filter, which is separate from the mask and configured to be in fluid communication with a face container defined by the mask. For example, the term “mask system” includes surgical masks, operating masks, isolation masks, laser masks, dental masks, patient care masks, filtering mask respirators, reusable respirators including one or more replaceable filter elements, and powered air-purifying respirators incorporating one or more filter elements designed to be replaced.

[0012] As used herein, the term “particle size” refers to the diameter of the particle, as determined as described in ISO 11171:2016.

[0013] As used herein, "continuous microfiber" refers to microfiber with an aspect ratio (i.e., length to transverse dimension) of at least 5,000, or more preferably at least 10,000. References to "continuous microfiber layer" herein refer to a layer comprising continuous microfibers (as opposed to chopped microfibers). While a continuous microfiber layer is preferably formed by a fiber-forming process that produces continuous microfibers, the resulting layer may comprise only one or more types of continuous microfibers. That is, a continuous microfiber layer may comprise one or more microfibers that have been planed to an aspect ratio of at least 5,000, or more preferably at least 10,000.

[0014] As used herein, “chopped strands” refers to strands with an aspect ratio (i.e., the ratio of length to width) of less than 5,000, less than 2,500, or less than 1,000. Typically, chopped strands have an aspect ratio of at least 10 and up to 5,000.

[0015] As used herein, "hybrid" fibers or "hybrid fiber structures" refer to fibers having at least two different diameters, wherein fibers with an average first diameter and fibers with an average second diameter are mixed, i.e., wherein the fibers are mixed within the same layer (or layer) of the medium structure due to the simultaneous formation or deposition of the fibers, or by using very short pulses (e.g., up to 10 seconds, up to 20 seconds, or up to 30 seconds) of each polymer solution. When visualized using top-down SEM images, fibers with the first average diameter can be observed located below and above fibers with the second average diameter.

[0016] As used herein, “layered” fibers or “layered fiber structure” refers to fibers having at least two different diameters, wherein the fiber having a first average diameter is substantially not entangled with the fiber having a second average diameter, as the fibers of different diameters are applied alternately to the substrate.

[0017] As used herein, unless otherwise indicated, capillary flow porosimetry is used to determine the pore size (e.g., P5, P50, and P95) and the ratio of pore sizes (e.g., P95 / P50). Capillary flow porosimetry can be performed using a continuous pressure scan mode. Using silicone oil with a surface tension of 20.1 dynes / cm and a wetting contact angle of 0 can be useful as the wetting fluid. Samples can be initially tested in a dry state (changing from low pressure to high pressure) and then in a wet state (again changing from low pressure to high pressure). This test is typically performed under ambient temperature conditions (e.g., 20°C to 25°C). 256 data points can be collected over the entire pressure scan range of both the dry and wet profiles. Typically, tortuosity factors and / or shape factors are not used (i.e., factors equal to 1 can be used for comparison with other test methods that use adjustment factors).

[0018] As used herein, the value P(x%) is the calculated orifice size when the wet curve is equal to (100-x)% of the dry curve, as determined using the methods described herein. Although a calculated value, this can be understood as representing the point where x% of the total flow through the layer passes through an orifice of that size or smaller. For example, P50 (average flow orifice size) represents the point where the wet curve is equal to half the dry curve and can be considered as an orifice size such that 50% of the total flow through the layer passes through an orifice of that size or smaller.

[0019] The average pore size (e.g., the average maximum pore size) can be calculated from the average of at least three measurements obtained from at least three different sample locations. A separate measurement of the maximum pore size (which may also be referred to as P100) can be detected at the bubbling point, which is found after the fluid begins to pass through the sample, and the three consecutive measurements increase by at least 1%, with 256 data points collected throughout the scan at a rate of approximately 17 data points per minute.

[0020] As used herein, the “β ratio” or “β” is the ratio of upstream particles to downstream particles under steady flow conditions (ISO 16889:2008), as illustrated in the examples. A higher filter efficiency results in a higher β ratio. The β ratio is defined as follows: , Where N d,U It is the upstream particle count per unit fluid volume for particles with a diameter of d or larger, and N d,D This is the downstream particle count per unit fluid volume for particles with a diameter of d or larger. If present, the subscript appended to β indicates the particle size at the reported ratio.

[0021] As used herein, the “total β ratio” or “total β” is the ratio of the sum of all upstream particles during the determination to the sum of all downstream particles during the test (where the test is run at a pressure of 25 psi (172 kPa): , Where N d,U It is the upstream particle count per unit fluid volume for particles with a diameter of d or larger, and N d,D This is the downstream particle count per unit fluid volume for particles with a diameter of d or larger. If present, the subscript appended to β indicates the particle size at the reported ratio.

[0022] As used in this article, "filtration efficiency" or "efficiency" refers to the percentage of contaminants removed by the filter, calculated as follows: , Where e is the filtration efficiency, and β is as defined above. Therefore, the efficiency mentioned in this article is the cumulative efficiency. If present, the subscript appended to e indicates the particle size at which the reported ratio is being calculated.

[0023] As used herein, “pressure drop” (also referred to herein as “dP” or “ΔP”) refers to the pressure (applied by a pump) required to force fluid through a filter or filter medium (before the addition of contaminants) at a specific fluid velocity. Unless otherwise specified, pressure drop is measured as described in ISO 3968:2017.

[0024] As used herein, the term "substantially free" indicates that the filter media does not contain any amount of the listed components (e.g., glass fibers or resins) that substantially contribute to the activity or function of the filter media. This term is intended to include trace amounts of components that do not substantially contribute to the filtration performance of the filter media. For example, a substantially glass-free filter media may include less than 1 wt% glass fibers. For example, a substantially resin-free filter media may include less than 5 wt% resin. For example, a substantially glass-free filter media may include less than 1 wt% glass fibers. For example, a substantially resin-free filter media may include less than 5 wt% resin.

[0025] As used herein, the term “free” indicates that the filter media does not contain a certain amount of the listed components (e.g., glass fiber or resin). For example, “glass-free” filter media does not contain any glass, and “resin-free” media does not contain any resin.

[0026] The terms "preferred" and "ideally" refer to embodiments of the invention that may provide certain benefits in certain circumstances. However, other embodiments may also be preferred in the same or other circumstances. Furthermore, the description of one or more preferred embodiments does not imply that other embodiments are not useful, and is not intended to exclude other embodiments from the scope of the invention.

[0027] Where the term "comprising" and its variations appear in the specification and claims, these terms are not restrictive. Such terms should be understood to imply inclusion of the stated steps or elements or a group of steps or elements, but not to exclude any other steps or elements or any other group of steps or elements.

[0028] "Comprising of..." means including and limited to anything contained in the phrase "comprising of...". Therefore, the phrase "comprising of..." indicates that the listed element is necessary or mandatory, and other elements may not be present. "Substantially comprising..." means including any element listed in the phrase, and limited to other elements that do not impede or contribute to the function or role specified in this disclosure for the listed element. Therefore, the phrase "substantially comprising..." indicates that the listed element is necessary or mandatory, but other elements are optional and may or may not be present, depending on whether they substantially affect the function or role of the listed element.

[0029] Unless otherwise stated, “a type”, “the” and “at least one type” are used interchangeably and mean one type or more than one type.

[0030] As used herein, the term “or” is generally used in its usual sense, which includes “and / or”, unless the context clearly indicates otherwise.

[0031] The term “and / or” means one or all of the listed elements or any combination of two or more of the listed elements.

[0032] Unless otherwise stated, any reference to standard methods (e.g., ASTM, TAPPI, AATCC, ISO, etc.) refers to the most recent available version of that method at the time of submission of this disclosure.

[0033] Furthermore, in this document, the numerical range described by endpoints includes all numbers falling within the range (e.g., 1 to 5 includes 1, 1.5, 2, 2.75, 3, 3.80, 4, 5, etc.).

[0034] In this article, “up to” a certain number (e.g., up to 50) includes that number (e.g., 50).

[0035] The terms “within the range” or “within a certain range” (and similar statements) include the endpoints of the range being stated.

[0036] For any method disclosed herein that includes discrete steps, the steps can be performed in any feasible order. Furthermore, any combination of two or more steps can be performed simultaneously, where appropriate.

[0037] All headings are for the reader's convenience and should not be used to limit the meaning of the text that follows the heading, unless otherwise specified.

[0038] Throughout this specification, the terms "one embodiment," "an embodiment," "some embodiments," or "a number of embodiments" refer to specific features, configurations, compositions, or characteristics described in connection with said embodiment, which are included in at least one embodiment of this disclosure. Therefore, the appearance of such phrases throughout this specification does not necessarily refer to the same embodiment of this disclosure. Furthermore, in one or more embodiments, specific features, configurations, compositions, or characteristics may be combined in any suitable manner.

[0039] Unless otherwise stated, all figures indicating the quantity of components, molecular weight, etc., used in the specification and claims should be understood to be modified by the term "about" in all cases. When used herein in conjunction with the quantity measured, the term "about" refers to a variation in the measured quantity as would be expected by a person skilled in the art to perform the measurement and to operate with a level of care commensurate with the purpose of the measurement and the accuracy of the measuring equipment used. Therefore, unless otherwise indicated to the contrary, the numerical parameters set forth in this specification and claims are approximations, which may vary depending on the desired characteristics sought to be obtained by the invention. At least, and not in an attempt to limit the scope of the claims, each numerical parameter should be interpreted at least according to the number of significant digits reported and by applying general rounding methods.

[0040] While the numerical ranges and parameters illustrating the broad scope of the invention are approximate, the values ​​described in the specific examples are reported as precisely as possible. However, all values ​​inherently contain ranges that are necessarily generated by the standard deviations found in their respective test measurements.

[0041] The above summary of the invention is not intended to describe every disclosed embodiment or implementation of the invention. The following description illustrates illustrative embodiments in more detail. Throughout this application, guidance is provided by a list of examples that can be used in various combinations. In each case, the enumerated list is intended only as a representative group and should not be construed as an exclusive list. Attached Figure Description

[0042] Figure 1A This is a schematic cross-sectional view of an exemplary filter media layer disclosed herein. Figure 1B This is a schematic cross-sectional view of an exemplary filter element comprising two layers of filter media disclosed herein.

[0043] Figures 2A to 2F This is a schematic cross-sectional view of an exemplary filter medium, which includes an electrostatically charged filter medium, a microfiber layer, and a loosely woven cloth. Figure 2G This is a schematic cross-sectional view of an exemplary filter medium comprising two layers of fine fibers and two loosely woven fabrics. Figures 2H to 2M This is a schematic cross-sectional view of an exemplary filter medium, which includes an electrostatically charged filter medium, a microfiber layer, and a loosely woven fabric, showing the flow direction (black arrow pointing from upstream to downstream).

[0044] Figure 3 This is a perspective view of an illustrative embodiment of a mask system in the form of a reusable respirator.

[0045] Figure 4 It depicts the appropriate position on the wearer's body. Figure 3 The respirator.

[0046] Figure 5 An illustrative embodiment of a mask system in the form of a surgical mask is depicted, which incorporates one or more filtering elements as described herein.

[0047] Figure 6 yes Figure 5 Surgical mask along Figure 5 The cross-sectional view taken by line 6-6 in the figure.

[0048] Figure 7 This is a perspective view of an illustrative embodiment of a mask system in the form of a filtering mask respirator, which includes a molded cup-shaped mask incorporating one or more filtering elements as described herein.

[0049] Figure 8 yes Figure 7 An exploded view of the face mask.

[0050] Figure 9 A schematic diagram of the exemplary medium further described in Example 1 is shown.

[0051] Figure 10 A schematic diagram of an exemplary medium, further described in Example 2, is shown.

[0052] Figure 11 A schematic diagram of an exemplary pleating of the medium, further described in Example 3, is shown.

[0053] Figure 12 A schematic diagram of another example of the mask system described herein is shown.

[0054] Figure 13 A schematic exemplary plate filter element conforming to the technology disclosed herein is depicted.

[0055] Figure 14 Depicting conformity Figure 13 An exemplary cross-sectional view of a plate-type filter element.

[0056] Figure 15 The grading efficiency and particle size of the filter element described in Example 4 are shown.

[0057] Figure 16 A graphical representation of a simulated glassless filter medium is shown, comprising 14 µm diameter bicomponent fibers, 0.7 µm diameter PET fibers, 2.5 µm diameter PET fibers, and 1 µm diameter fibrillated rayon fibers, as further described in Example 5. The simulation of the rayon fibers does not depict the full range of their bundle properties.

[0058] Figure 17 The following diagram illustrates the determination of β in hand-copied sheets prepared as described in Example 6. 4 µm = 10,000 and the measured test β value, and the hand-copied sheet comprises 24 g / m of 700 nm diameter PET fibers (round) with different amounts. 2 The dataset includes 14 µm diameter bicomponent fibers, or 14 µm diameter bicomponent fibers with varying amounts of 700 nm diameter PET fibers, 1 µm diameter fibrillated rayon fibers (lyocell fibers), and 2.5 µm diameter PET fibers (square fibers). Curve fitting was used in Excel to calculate the trend line for each dataset.

[0059] Figure 18 The β value measured for a medium prepared as described in Example 7 is shown. 4 µm .

[0060] Figure 19A The load capacity of the plate prepared as described in Example 8 is shown. Figure 19B The efficiency of the plate prepared as described in Example 8 is shown.

[0061] Figure 20A A schematic diagram of an exemplary flat plate that can be prepared as described in Example 4 in some embodiments is shown. Figure 20B A schematic diagram of an exemplary flat panel is shown. Figure 20C A schematic diagram of an exemplary flat plate that can be prepared as described in Example 9 in some embodiments is shown.

[0062] Figures 21A to 21D Exemplary filter media and filter element constructions are shown, as further described herein.

[0063] Figure 22A A schematic diagram illustrating an exemplary embodiment of a continuous fine fiber layer of the filter medium described herein is shown, wherein the continuous fine fiber layer comprises a mixture of fibers of different diameters in different layers of the continuous fine fiber layer. Figure 22B Exemplary images of a large microfiber layer deposited on a loosely woven nylon fabric are shown at 500x magnification (top view) and 2000x magnification (bottom view). Figure 22C An exemplary SEM image (magnified 1000x) of a sample prepared as described in Example 12 (fine fibers laid directly on a loosely woven fabric) is shown. Figure 22D An exemplary SEM image (magnified 1000x) of a sample prepared as described in Example 12 (small fine fibers covering large fine fibers) is shown. Figure 22E Exemplary SEM images (1000x magnification) of samples prepared using the following as described in Example 13 are shown: using solution 1 to obtain small fine fibers (left subplot), using solution 1 and solution 2 to obtain mixed fine fibers with mixed (small and large) diameters (center subplot), and using solution 2 to obtain large fine fibers (right subplot). Figure 22F A schematic diagram of a sample prepared as described in Example 12 (fine fibers laid directly on a loosely woven fabric) is shown. Figure 22G A schematic diagram is shown of a sample prepared as described in Example 12 (fine fibers covering macrofibers, with the macrofibers laid directly on a loosely woven fabric). Figures 22H to 22M A schematic diagram of an exemplary dielectric configuration is shown. In each configuration, a support layer is not shown, but it is typically located downstream of the dielectric. In each configuration, an efficiency layer is not shown but may be added; if included, this efficiency layer is typically located upstream of the dielectric.

[0064] Figure 23 The pressure drop (efficiency layer (Donaldson Synteq XP™ synthetic liquid media with a 10-micron efficiency rating), the continuous microfiber layer, and the support layer (sparse cloth)) of the filter media (XP / fine fiber / loose cloth) as described in Example 10 are shown.

[0065] Figure 24A An exemplary SEM image of the medium described in Example 13A at 2500x magnification is shown, the medium comprising fibers with a diameter of 200 nm to 300 nm in a continuous layer of fine fibers on a support layer. Figure 24BAn exemplary SEM image of the medium described in Example 13B at 2500x magnification is shown, the medium comprising fibers with a diameter of 350 nm to 450 nm in a continuous layer of fine fibers on a support layer.

[0066] Figure 25 The performance of a medium comprising a support layer and a continuous fiber layer, as described in Example 14, is compared (using factor of quality (FOM) indicators) as the solids content in the electrospinning precursor solution varies. The expected change in solids content alters the diameter of the continuous fibers.

[0067] Figures 26A to 26B The maximum pore size of the composite material is shown for a composite material comprising one or more continuous fine fiber layers and a support layer. Figure 26A ) or average flow orifice diameter of composite material ( Figure 26B The initial pressure drop is plotted as further described in Example 15. Triangles represent samples that maintained the integrity of the fine fiber structure throughout the test; squares represent samples that suffered fine fiber bursting during the test.

[0068] Figure 27 The cumulative flow orifice size distribution of the sample described in Example 16 is shown.

[0069] Figure 28A An exemplary cross-sectional image of a continuous fine fiber layer on a support layer is shown. Figures 28B to 28D Exemplary images of methods for measuring the thickness of continuous fine fiber layers are shown, as further described in these examples.

[0070] While the accompanying drawings (which may be drawn to scale or not) illustrate embodiments of the invention, other embodiments are contemplated as noted in the discussion. In all instances, this disclosure presents the invention by way of illustration and not limitation. It should be understood that those skilled in the art can devise many other modifications and embodiments that fall within the scope of this invention. Detailed Implementation

[0071] In one aspect, this disclosure describes a nonwoven filter medium comprising a fibrous medium, which includes bicomponent fibers, glass fibers, and microfibrillated cellulose fibers.

[0072] In another aspect, this disclosure describes a filter medium comprising an electrostatically charged filter medium, a fine fiber layer, and a loosely woven cloth.

[0073] On the other hand, this disclosure describes a filter medium comprising two layers of fine fibers and two loosely woven fabrics.

[0074] In another aspect, this disclosure describes a glass-free filter medium and a glass-free composite material comprising multiple layers of filter media. In some embodiments, the filter medium or composite material preferably exhibits capacity and efficiency comparable to or better than similar glass-containing filter media.

[0075] In another aspect, this disclosure describes a filter medium comprising a support layer and a continuous layer of fine fibers.

[0076] In some embodiments, the filter media is configured for air filtration.

[0077] In some embodiments, the filter medium is preferably incorporated into a face mask system having a mask. As defined above, a "face mask" is a component configured to extend across at least a portion of the wearer's face.

[0078] In some embodiments, a face shield as described herein can be used as a piece of protective clothing designed to protect portions of the wearer's face (including the mucous membrane areas of the wearer's nose or mouth) from contact with airborne contaminants such as bodily fluids. The face shield can act as a barrier to hazards for the wearer, and additionally or alternatively, it can also act as a barrier to prevent the wearer from becoming a source of contamination.

[0079] In the following description, reference is made to the accompanying drawings, which form a part of the description and in which specific embodiments are illustrated by way of illustration. It should be understood that other embodiments may be utilized and changes may be made without departing from the scope of the invention.

[0080] Part A. Filter media including microfibers

[0081] The nonwoven filter media disclosed herein include fibrous media, which include bicomponent fibers, glass fibers, and microfibrillated fibers. Such microfibrillated fibers are typically used to reinforce fibrous media (i.e., to improve at least one property of the fibrous media or to create at least one new property therein). These properties include, for example, strength (e.g., tensile strength or burst strength), efficiency, durability, processability, filtration efficiency, or combinations thereof.

[0082] In some embodiments, the fibrous medium may further include additional fibers that affect the properties or characteristics of the medium.

[0083] In some embodiments, the nonwoven filter media may further include a nanofiber layer.

[0084] The fibrous “base medium” forms the majority (i.e., greater than 50%) of the total weight of the nonwoven filter medium. The fibrous medium can include all components of the nonwoven filter medium except for the nanofiber layer. Glass fiber media and bicomponent fibrous media that can be used as fibrous media are disclosed, for example, in U.S. Patent Nos. 7,309,372, 7,314,497, and 2006 / 0096932. These fibers are thermally bonded into a nonwoven web. This medium has a useful pore size and filtration efficiency derived from the combined fibrous components.

[0085] In some embodiments, the microfibrillated cellulose fibers and bicomponent fibers are uniformly distributed throughout the thickness of the fiber medium. In some embodiments, including, for example, when the fiber medium is formed from two different feeds, although the microfibrillated cellulose fibers and bicomponent fibers are uniformly distributed in each feed and the microfibrillated cellulose fibers and bicomponent fibers will be distributed throughout the thickness of the fiber medium, the microfibrillated cellulose fibers and bicomponent fibers may not be uniformly distributed throughout the thickness of the resulting fiber medium.

[0086] As shown in Figure 1, typically and preferably, the glass fibers form a gradient throughout the thickness of the layer (i.e., the sheet), such that a high concentration of glass fibers is located on one main surface of the layer (the bottom surface shown in Figure 1) and little or no (typically less than 1 wt%) of glass fibers are located on the other main surface (the top surface shown in Figure 1). In some embodiments, the glass fibers form a continuous gradient (i.e., a continuous increase (or decrease) in the concentration of glass fibers may be observed). However, in some embodiments, the glass fibers are present in discrete layers.

[0087] Referring to Figure 2, the filter element of the mask system disclosed herein may include at least two layers or at least two media as described herein. Each layer includes two main surfaces. Typically and preferably, microfibrillated cellulose fibers and bicomponent fibers are uniformly distributed throughout the media layer, and glass fibers form a gradient from a high concentration at one main surface of the layer to few or no glass fibers at the other main surface. In some embodiments, the gradient may be a continuous gradient. The two main surfaces with high glass concentrations are oriented adjacent to each other. This orientation, in particular, restricts the escape of glass fibers from the filter element during use.

[0088] Here, in fibrous or nonwoven filter media, the total amount of components is 100 wt%.

[0089] Microfiber

[0090] Nonwoven filter media include microfibrillated fibers. As used herein, microfibrillated fibers are fibers that have been processed to form fibers with a higher surface area and branching structure than unprocessed fibers.

[0091] In some embodiments, the microfibrillated fiber may be a microfibrillated acrylic fiber, including, for example, fibrillated CFF fiber (available from Engineered Fiber Technology, Sheldon, Connecticut). In some embodiments, the microfibrillated fiber may be a microfibrillated cellulose fiber, including, for example, rayon, such as lyocell or Tencel. In some embodiments, the microfibrillated fiber may be a microfibrillated para-aramid fiber, including, for example, Twaron pulp (Teijin Aramid, BV, Netherlands). In some embodiments, the microfibrillated fiber may be a microfibrillated liquid crystal polymer (LCP) fiber, including, for example, microfibrillated Vectran fiber (available from Engineered Fiber Technology, Sheldon, Connecticut). In some embodiments, the microfibrillated fiber may be a microfibrillated poly(p-benzodioxazole) (PBO) fiber, including, for example, fibrillated Zylon fiber (available from Engineered Fiber Technology, Sheldon, Connecticut).

[0092] As used herein, microfibrillated cellulose (MFC) refers to a material as defined by G. Chinga-Carrasco in Nanoscale Research Letters, 2011, 6:417: “MFC materials may consist of (1) nanofibers, (2) fibrous particles, (3) fiber fragments, and (4) fibers. This implies that MFC is not necessarily synonymous with microfibers, nanofibers, or any other cellulose nanostructure. However, properly manufactured MFC materials contain nanostructures, i.e., nanofibers, as the main component.” The diameters of these components (or, for microfibrillated cellulose fibers, “lateral dimensions”) are reproduced in Table 1 of the same document and are as follows: (1) nanofibers (< 0.1 µm); (2) fibrous particles (< 1 µm); (3) fibers or fiber fragments (10 µm to 50 µm).

[0093] Furthermore, as used herein, the term “microfibrillated cellulose” does not include dry-milled cellulose (also known as micronized cellulose or fine cellulose) and does not include microcrystalline cellulose obtained by removing the amorphous portion through acid hydrolysis, as described in U.S. Patent No. 5,554,287.

[0094] In some embodiments, the microfibrillated cellulose fibers used do not have a "dendritic structure" (as described in U.S. Patent Publication No. 2012 / 0043038), wherein the described fibrillation process causes external and internal segments of the fiber surface to partially separate from the host fiber structure and become filaments attached to the host fiber structure via a segment. For example, such filaments provide additional structure on the fiber for attachment to other fibers in a paper structure. This is undesirable in some embodiments.

[0095] In some embodiments, most microfibrils have a lateral dimension (e.g., two-dimensional width) of up to 1 micrometer, up to 1.5 micrometers, up to 2 micrometers, up to 3 micrometers, or up to 4 micrometers. In some embodiments, most microfibrils have a lateral dimension of at least 0.5 micrometers or at least 0.7 micrometers. In an exemplary embodiment, most microfibrils have a lateral dimension in the range of 0.5 micrometers to 1.5 micrometers.

[0096] In some embodiments of the nonwoven filter media disclosed herein, the majority (i.e., greater than 50%) of the microfibrillated cellulose fibers have a transverse dimension of up to 4 micrometers. In some embodiments of the nonwoven filter media disclosed herein, the majority (i.e., greater than 50%) of the microfibrillated cellulose fibers have a transverse dimension of 700 nm to 4 micrometers.

[0097] While not intended to be limiting, microfibrillated cellulose fibers can increase the strength (including wet strength) and / or filtration efficiency of fibrous media. This occurs when resins known as certain filter media (e.g., synthetic resins such as phenolic resins, acrylic resins) are not used, or when reduced amounts of such resins are used. In some embodiments of this disclosure, the nonwoven filter media of this disclosure comprise less than 15 wt%, or less than 10 wt%, or less than 5 wt%, or less than 2 wt% of resin based on the total weight of the nonwoven filter media. Typically, resin is not used in the nonwoven filter media of this disclosure.

[0098] Microfibrillated cellulose fibers can be prepared using conventional techniques. For example, microfibrillated cellulose can be prepared using the process disclosed in U.S. Patent Publication No. 2009 / 0221812. In short, this involves treating cellulose pulp with a small amount of wood-degrading cellulase, followed by high-shear processing using a microfluidic. Processing in the microfluidic can be performed using the interacting chambers in microfluidic devices of 87 µm, 100 µm, and 200 µm at pressures ranging from 5000 psi to 30000 psi, with one to three passes through the device. Preferably, a single pass through a 200 µm chamber is performed at 5000 psi to 8000 psi.

[0099] In a preferred embodiment, southern cork cellulose microfibrils can be obtained by first enzymatically treating the cellulose, denaturing the enzymes with heat, and then processing it using a high-shear processing device. Fiber size can be controlled by processing conditions; that is, smaller interaction chamber sizes, more passage through the microfluidizer, and / or higher operating pressures produce smaller fibers.

[0100] Multiple microfibrils are combined within the fibrous medium (i.e., distributed throughout the fibrous medium) to form a filter medium (also referred to herein as a "filtration medium" or "filter medium").

[0101] In some embodiments, the use of microfibrillated cellulose fibers can effectively enhance at least one property of the fiber medium compared to a fiber medium without microfibrillated cellulose fibers. Typically, microfibrillated cellulose fibers are present in the fiber medium at a weight percentage (wt%), or at least 2 wt%, or at least 3 wt%, based on the total weight of the nonwoven fiber medium. Microfibrillated cellulose fibers are present in the fiber medium at a weight of up to 49 wt%, or up to 20 wt%, or up to 18 wt%, based on the total weight of the fiber medium.

[0102] Fiberglass

[0103] Glass fibers provide pore size control and work in conjunction with other fibers in the medium to obtain media with considerable flow rates, high capacity and high efficiency.

[0104] "Glass fiber" is a fiber made from various types of glass. Glass fibers used in this disclosure include glass types known by the following names: A, C, D, E, zero boron E, ECR, AR, R, S, S-2, N, etc., and generally include any glass that can be made into fibers by a drawing process used to manufacture reinforcing fibers or a spinning process used to manufacture insulating fibers.

[0105] In some embodiments, the glass fibers have an average transverse dimension (typically a diameter) of at least 0.5 micrometers (i.e., 500 nm) and typically at least 1 micrometer. In some embodiments, the glass fibers have an average transverse dimension (typically a diameter) of no more than 30 micrometers, no more than 20 micrometers, and typically no more than 15 micrometers. Typically, the glass fibers have a transverse dimension of at least 500 nm and typically no more than 20 micrometers. In some embodiments, the glass fibers are typically used as an aggregate of fibers with a diameter of about 0.1 to 10 micrometers and an aspect ratio (length divided by diameter) of about 10 to 10,000.

[0106] In some embodiments, glass fibers are present in the fiber medium in an amount of at least 10 wt% or at least 20 wt% based on the total weight of the fiber medium. In some embodiments, glass fibers are present in the fiber medium in an amount of up to 80 wt% or up to 50 wt% based on the total weight of the fiber medium.

[0107] In some embodiments, the fiber medium may have two main surfaces, and the glass fibers may form a gradient from a high concentration of glass fibers on one main surface to little or no glass fibers on the other main surface. For example, in an exemplary embodiment, the glass fibers are present on one main surface in an amount of 10 wt% to 80 wt% based on the total weight of the fiber medium, and on the other main surface in an amount of 0 wt% to 10 wt% based on the total weight of the fiber medium.

[0108] Bicomponent adhesive fiber

[0109] The filter media consists of bicomponent fibers. Any suitable bicomponent fiber can be used, and the bicomponent fiber can be selected based on the intended use of the media.

[0110] In some embodiments, the filter media comprises at least 25 wt%, at least 30 wt%, at least 35 wt%, at least 40 wt%, at least 45 wt%, at least 50 wt%, at least 55 wt%, at least 60 wt%, at least 65 wt%, or at least 70 wt% of bicomponent fibers. In some embodiments, the filter media comprises up to 30%, up to 35 wt%, up to 40 wt%, up to 45 wt%, up to 50 wt%, up to 55 wt%, up to 60 wt%, up to 65 wt%, up to 70 wt%, up to 75 wt%, or up to 85 wt% of bicomponent fibers. In an exemplary embodiment, the filter media comprises 25 wt% to 85 wt% of bicomponent fibers. In another exemplary embodiment, the filter media comprises 25 wt% to 75 wt% of bicomponent fibers. In yet another exemplary embodiment, the filter medium comprises 25 wt% to 70 wt% of bicomponent fibers. In yet another exemplary embodiment, the filter medium comprises 50 wt% of bicomponent fibers.

[0111] In some embodiments, the bicomponent fiber has a fiber diameter of at least 1 micrometer, at least 5 micrometers, at least 10 micrometers, at least 15 micrometers, or at least 20 micrometers. In some embodiments, the bicomponent fiber has a fiber diameter of up to 5 micrometers, up to 10 micrometers, up to 15 micrometers, up to 20 micrometers, up to 25 micrometers, or up to 30 micrometers. In an exemplary embodiment, the bicomponent fiber has a fiber diameter in the range of 5 micrometers to 25 micrometers. In another exemplary embodiment, the bicomponent fiber has a fiber diameter of 14 micrometers.

[0112] In some embodiments, the bicomponent fiber has a fiber length of at least 0.1 cm, at least 0.5 cm, or at least 1 cm. In some embodiments, the bicomponent fiber has a fiber length of up to 0.5 cm, up to 1 cm, up to 5 cm, up to 10 cm, or up to 15 cm. In an exemplary embodiment, the bicomponent fiber has a fiber length in the range of 0.1 cm to 15 cm. In another exemplary embodiment, the bicomponent fiber has a fiber length of 6 mm.

[0113] In some embodiments, the bicomponent fiber includes a structural polymer portion and a thermoplastic binder polymer portion, wherein the melting point of the structural polymer portion is higher than that of the binder polymer portion.

[0114] The structural polymer portion and the adhesive polymer portion can be made of any suitable material. For example, the structural polymer portion may include PET and the adhesive polymer portion may include copolymer PET (coPET). In another example, the structural polymer portion may include PET and the adhesive polymer portion may include polyethylene (PE), PET, nylon, polypropylene (PP), polytetrafluoroethylene (PTFE), polyethersulfone (PES), polyphenylene sulfide (PPS), meta-aramid, or para-aramid. In another example, the adhesive polymer portion may include polyethylene (PE), polylactic acid (PLA), nylon, ethylene vinyl alcohol (EVOH), polyvinyl chloride (PVC), polyvinylidene fluoride (PVDF) (e.g., Kynar), or any other polymer or modified polymer designed to have a lower melt temperature than the core structural polymer.

[0115] In some embodiments, the structural polymer portion is the core, and the thermoplastic adhesive polymer portion is the sheath of the bicomponent fibers.

[0116] In some embodiments, the structural polymer portion of the bicomponent fiber has a melting point of at least 240°C and the adhesive polymer portion of the bicomponent fiber has a melting point of up to 115°C. An exemplary bicomponent fiber in which the structural polymer portion has a melting point of at least 240°C and the adhesive polymer portion has a melting point of up to 115°C is 271P, i.e., a 14 µm diameter fiber available from Advansa (Halm, Germany).

[0117] In some embodiments, the structural polymer portion of the bicomponent fiber has a melting point of at least 240°C and the adhesive polymer portion of the bicomponent fiber has a melting point in the range of 100°C to 190°C. In one exemplary embodiment, the structural polymer portion of the bicomponent fiber has a melting point of at least 240°C and the adhesive polymer portion of the bicomponent fiber has a melting point in the range of 120°C to 170°C. In another exemplary embodiment, the structural polymer portion of the bicomponent fiber has a melting point of at least 240°C and the adhesive polymer portion of the bicomponent fiber has a melting point in the range of 140°C to 160°C.

[0118] Exemplary bicomponent fibers in which the structural polymer portion has a melting point of at least 240°C and the binder polymer portion has a melting point in the range of 100°C to 190°C are TJ04CN (with a binder polymer portion melting point of 110°C) and TJ04BN (with a binder polymer portion melting point of 150°C), both of which are available from Teijin Fibers Limited of Osaka, Japan; 271P (with a binder polymer portion melting point of 110°C), which is available from Advansa in Hamm, Germany; and T-202 or T-217 (each with a binder polymer portion melting point of 180°C), both of which are available from FiberInnovation Technology, Inc. in Johnson City, Tennessee.

[0119] In some embodiments, the bicomponent fiber may include a first bicomponent fiber and a second bicomponent fiber. In an exemplary embodiment, the bicomponent fiber may include a first bicomponent fiber, wherein the structural portion has a melting point of at least 240°C and the adhesive polymer portion has a melting point of up to 115°C; and a second bicomponent fiber, wherein the structural polymer portion has a melting point of at least 240°C and the adhesive polymer portion has a melting point in the range of 100°C to 190°C. For example, the bicomponent fiber may include both Advansa 271P and TJ04BN.

[0120] Optional additional fibers

[0121] In some embodiments, the fibrous medium may further include additional fibers that affect the properties or characteristics of the medium.

[0122] In some embodiments, the fibrous medium may further include PET fibers, dyed fibers, conductive fibers, or combinations thereof. Combinations may include mixtures (e.g., PET fibers and conductive fibers) or overlapping combinations (e.g., dyed PET fibers).

[0123] In some embodiments, PET fibers may have a diameter between that of glass fibers or microfibrillated cellulose fibers (both about 1 µm) and that of bicomponent fibers (about 14 µm). In some embodiments, PET fibers may have a diameter of at least 2 µm, at least 3 µm, at least 4 µm, at least 5 µm, at least 6 µm, or at least 7 µm. In some embodiments, PET fibers may have a diameter of up to 3 µm, up to 4 µm, up to 5 µm, up to 6 µm, up to 7 µm, or up to 8 µm. In an exemplary embodiment, PET fibers may have a diameter in the range of 2 µm to 3 µm. In another exemplary embodiment, PET fibers may include Teijin TP04N (0.06 dtex × 3 mm) (Teijin Fibers, Limited, Tokyo, Japan).

[0124] Without being bound by theory, it is believed that using fibers with a diameter between that of glass fibers and microfibrillated cellulose fibers and that of bicomponent fibers can help improve the stability of the structure, thereby preventing the smaller fibers from shifting during use in the medium.

[0125] In some embodiments, PET fibers may include crimped PET fibers. For example, in an exemplary embodiment, the crimped PET fibers include Teijin TA34A (2.2 dtex × 10 mm) (Teijin Fibers, Limited, Tokyo, Japan).

[0126] Not wanting to be bound by theory, it is believed that using crimped fibers can increase the bulkiness of the structure.

[0127] In some embodiments, the additional fiber may include dyed fiber, such as dyed PET fiber. For example, in an exemplary embodiment, the dyed PET fiber includes Minifiber blue PET fiber (5.0 denier × 6 mm) (MiniFIBERS, Inc., Johnson City, Tennessee).

[0128] Dyed fibers can be used to visualize the orientation of the media, including, for example, which surfaces comprise glass fibers. In some embodiments, a small amount of dyed fiber that does not significantly affect the performance of the filter media may be used.

[0129] In some embodiments, the additional fibers may include a conductive material. In an exemplary embodiment, the additional fibers may include carbon fibers and / or activated carbon fibers.

[0130] In some embodiments, the additional fibers may include absorbent material. In an exemplary embodiment, the additional fibers may include activated carbon fibers.

[0131] Fine fiber layer

[0132] If included, the fine fiber layer may include the continuous fine fiber layer as described in the continuous fine fiber portion of section F.

[0133] In some embodiments, the fiber layer may be an electrospun layer. When the fiber layer is an electrospun layer, the fibers can be deposited directly on the fiber medium. In embodiments where a gradient of glass fiber concentration is formed from one main surface of the layer to another main surface with little or no glass fiber, the fibers can be deposited directly on the side of the fiber medium with the high concentration of glass fiber.

[0134] In embodiments where fine fibers are deposited directly onto a fiber medium via electrospinning, it may be advantageous to include conductive fibers in the fiber medium. In exemplary embodiments, the conductive fibers may include carbon fibers and / or activated carbon fibers.

[0135] Without being bound by theory, it is believed that adding a microfiber layer can increase the strength of the fiber medium, reduce glass fiber migration, and / or provide additional means of capturing glass fibers and preventing them from migrating downstream.

[0136] In an exemplary embodiment, the fiber layer may include Ultra-Web, which is available from Donaldson Company, Inc. (Bloomington, Minnesota).

[0137] Preparation of filter media including microfibrillated cellulose

[0138] The filter media disclosed herein, comprising microfibrillated cellulose, is composed of a randomly oriented array of multi-component fibers, microfibrillated cellulose fibers, and glass fibers. This media can be prepared by methods such as wet web forming or air-laid web forming. Preferably, the process is a wet web forming process. The fibers are bonded together using a fusible (i.e., melt-bonded) polymer in the multi-component fibers.

[0139] In some embodiments of this disclosure, the nonwoven filter media of this disclosure comprises less than 15 wt%, or less than 10 wt%, or less than 5 wt%, or less than 2 wt%, of resin, based on the total weight of the nonwoven filter media. Typically, resin is not used in the nonwoven filter media of this disclosure.

[0140] A typical wet web-forming process for manufacturing the filter media disclosed herein includes producing a dispersion of multi-component fibers, glass fibers, and microfibrillated fibers, and optional additives in an aqueous liquid, draining the liquid from the resulting dispersion to produce a wet composition, and heating to form, bond, and dry the wet nonwoven composition to form the filter media.

[0141] In a preferred method of wet web forming, the filter medium is made from a diluted (0.05 wt% to 5 wt% solids in the feed) aqueous feed comprising a dispersion of fibrous material in an aqueous medium. The aqueous liquid of the dispersion is typically water, but may include various optional additives such as pH adjusters, surfactants, defoamers, flame retardants, viscosity modifiers, media treatment agents, colorants, etc. The aqueous liquid is typically removed from the dispersion by guiding it onto an inclined screen or other perforated support, thereby retaining the dispersed solids and allowing the liquid to pass through to produce a wet paper composition. Once a wet composition is formed on the support, it is typically further dehydrated by vacuum or other pressure, and further dried by evaporating the remaining liquid. After the liquid is removed, thermal bonding typically occurs by melting some portions of the thermoplastic fibers or other portions of the formed material. The molten material bonds the components into mechanically stable layers or sheets.

[0142] The media described herein can be manufactured on equipment of any scale, from laboratory hand-printing or hand-made sheet proportions to commercial-scale papermaking. For commercial-scale processes, filter media are typically processed using inclined screen papermaking machines, such as commercially available Fodorin paper machines, wire cylinders, Stevens vacuum cylinder formers, roto formers, inver formers, and delta formers. Preferably, a delta former is used.

[0143] To achieve the glass fiber gradient, a dual headbox wet web forming machine is typically used. In some embodiments, the headbox may preferably comprise an inclined headbox.

[0144] In some embodiments, when the fiber media is formed from two fiber mixtures (an upstream mixture and a downstream mixture), the fiber media may include each mixture in a mass ratio ranging from 20 / 80 to 80 / 20, from 25 / 75 to 75 / 25, from 30 / 70 to 70 / 30, or from 35 / 65 to 65 / 35. In an exemplary embodiment, the filter media exhibits a mass ratio in the range of 20 / 80 to 80 / 20. In another exemplary embodiment, the filter media exhibits a mass ratio in the range of 35 / 65 to 65 / 35.

[0145] Part B. Filter media including electrostatically charged filter media.

[0146] In some aspects, filter media include electrostatically charged filter media, microfiber layers, and loosely woven fabrics. (See also...) Figures 2A to 2F 。

[0147] The fine fiber layer is preferably in close contact with the loosely woven fabric. (See also...) Figures 2A to 2C In some embodiments, the fine fiber layer can be formed by deposition on a loosely woven fabric.

[0148] The electrostatically charged filter media has a first primary surface and a second primary surface. (See also...) Figure 2A In some embodiments, the first main surface is adjacent to the fiber layer. (See...) Figures 2A to 2B In some embodiments, the first primary surface is preferably in contact with the microfiber layer. Alternatively, the first primary surface of the electrostatically charged filter medium may be adjacent to the first primary surface of the sparsely woven fabric, and the microfiber layer may be adjacent to the second primary surface of the sparsely woven fabric. Figure 2C 。

[0149] In some embodiments, the filter medium may further comprise a second loosely woven cloth. Figures 2D to 2F 。

[0150] In some embodiments, when the first main surface of the electrostatically charged filter medium is in contact with the fine fiber layer, the second loosely woven fabric may be in contact with the second main surface of the electrostatically charged filter medium. Figure 2D 。

[0151] In some embodiments, where the microfiber layer is located between the first main surface of the electrostatically charged filter and the first sparse cloth, the second sparse cloth may be adjacent to (or in contact with) the second main surface of the electrostatically charged filter media. Figure 2E 。

[0152] In some embodiments, the microfiber layer may be located between two loosely woven fabrics. When the microfiber layer is located between two loosely woven fabrics, it may be adjacent to one or more loosely woven fabrics, or an additional layer may be located between the loosely woven fabric and the microfiber layer.

[0153] A loosely woven fabric layer in close contact with the fine fiber layer can be located upstream or downstream of the electrostatically charged filter medium. Figures 2H to 2M However, in some embodiments, the electrostatically charged filter media is located upstream of the fine fiber layer. Figure 2H This configuration may be beneficial because the electrostatically charged filter media can provide protection for the fine fiber layer during material processing.

[0154] In some embodiments, the electrostatically charged filter medium or loosely woven fabric is located upstream of the fine fiber layer. Figure 2H , Figure 2I , Figures 2K to 2M This configuration may be beneficial because the electrostatically charged filter media or loose cloth provides protection for the fine fiber layer during material processing.

[0155] While electrostatically charged filter media may exhibit high permeability or airflow even without a microfiber layer and loose fabric, adding a microfiber layer further enhances its efficiency, allowing the resulting filter media to meet certain criteria related to liquid particulate removal, as discussed further below. Furthermore, the microfiber layer improves efficiency without significantly reducing the flexibility of the electrostatically charged filter media (allowing for integration into filter elements and / or masks) and without significantly reducing permeability (allowing the mask wearer to breathe freely).

[0156] Electrostatically charged filter media

[0157] In some embodiments, the filter medium includes a filter medium carrying an electrostatic charge. In some embodiments, the electrostatically charged filter medium may include a meltblown layer.

[0158] Alternatively or alternatively, in some embodiments, the electrostatically charged filter medium comprises a non-meltblown layer. At the time of this invention, the supply of meltblown material was insufficient, making alternative materials particularly advantageous. An exemplary non-meltblown electrostatically charged filter medium is an electrostatic medium covering all or part of a loosely woven fabric material.

[0159] The term "electrostatic charging" refers to the process of placing an electric charge in and / or on a dielectric material such as polyolefins. The charge typically includes a layer of positive or negative charges trapped at or near the polymer surface, or a charge cloud stored within the polymer bulk. The charge may also include polarization charges, which are frozen when the dipoles of the molecules align. Methods for subjecting materials to charge are well known to those skilled in the art. These methods include, for example, thermal methods, liquid contact methods, electron beam methods, plasma methods, and corona discharge methods.

[0160] The electrostatic medium can be a triboelectric medium, an electret medium, or any other medium that is chargeable or relies on charging as the primary mechanism for particulate removal. In an exemplary embodiment, the electrostatic medium includes triboelectric fibers. Triboelectric fibers are known and can be formed, for example, using a mixture of: (1) polyolefin fibers such as polyethylene, polypropylene, or ethylene and propylene copolymers, and (2) fibers of another polymer, for example, fibers containing hydrocarbon functional groups substituted with halogen atoms (e.g., chlorine), or polyacrylonitrile fibers. Generally, the polyolefin fibers and other polymer fibers are included in the electrostatic medium in a weight ratio between about 60:40, about 20:80, or about 30:70.

[0161] meltblown

[0162] In some embodiments, the electrostatically charged filter medium includes an electrostatically charged meltblown filter layer.

[0163] In some embodiments, the meltblown filter layer is electrostatically charged. This charge can be induced by triboelectric charging or by applying a high-voltage charge. The former results from friction between the fiber and a grounded conductive surface, or from friction between two different fibers (one more positively charged and the other more negatively charged).

[0164] Alternatively, electrostatic charging can be performed using methods such as corona discharge or plasma discharge. These methods are known to those skilled in the art.

[0165] In some embodiments, the electrostatically charged meltblown filter layer of the filter medium disclosed herein is a high-efficiency filter layer. In some embodiments, the electrostatically charged meltblown filter layer exhibits at least 50% filtration efficiency at its rated velocity for 0.4-micron-sized DEHS (diethylhexyl sebacate) particles. Preferably, the filtration efficiency is at least 65%, or at least 85%, or at least 95%, or at least 99.5%, or at least 99.95% of particles with a size of 0.4 microns or the most penetrating particle size. In some embodiments, if not electrostatically charged, the meltblown filter layer exhibits at least 10% filtration efficiency at its rated velocity for 0.4-micron-sized DEHS (diethylhexyl sebacate) particles.

[0166] Electrostatic dielectric covering loose cloth

[0167] In some embodiments, the electrostatically charged filter medium may include an electrostatic material that covers all or part of a loosely woven fabric.

[0168] Electrostatic materials can contain a variety of fibers, including electrostatic fibers. Optionally, electrostatic materials are hybrid fibrous media comprising polypropylene and acrylic fibers. As used herein, the term "electrostatic fiber" refers to a fiber carrying an electrical charge. One advantage of incorporating electrostatic fibers is that the fibers not only mechanically capture contaminants but also apply electrostatic forces to the contaminants carrying the charge, thereby increasing the amount of contaminants removed from the airflow.

[0169] Electrostatic materials can have transmittance, for example, between approximately 250 ft. / min at 0.5 inches of water and approximately 750 ft. / min at 0.5 inches of water, or between approximately 280 ft. / min at 0.5 inches of water and approximately 750 ft. / min at 0.5 inches of water.

[0170] In some embodiments, the electrostatic material may have a filtration efficiency of about 20% to about 99.99% for particulate contaminants of 20 to 30 micrometers. For example, a suitable electrostatic material may have a filtration efficiency of greater than 20% for particulate contaminants of 20 to 30 micrometers; greater than 40% for particulate contaminants of 20 to 30 micrometers; or greater than 60% for particulate contaminants of 20 to 30 micrometers.

[0171] In some exemplary embodiments, the electrostatic material may have a filtration efficiency of less than 99.99% for particulate contaminants of 20 to 30 micrometers; less than 80% for particulate contaminants of 20 to 30 micrometers; or less than 60% for particulate contaminants of 20 to 30 micrometers.

[0172] A permeable sparse cloth can form at least a portion of a media structure, with the electrostatic material at least partially covering the permeable sparse cloth. In an exemplary embodiment, the electrostatic material will cover all or most of the permeable sparse cloth. In some embodiments, the electrostatic material and the sparse cloth are combined together (e.g., by lamination, thermal bonding, or photocalendering) prior to the production of the filter assembly and then formed into a media structure that produces at least a portion of the filter assembly.

[0173] In some embodiments, the permeable sparse cloth may be a polypropylene sparse cloth. An exemplary polypropylene sparse cloth has a permeability of approximately 500 feet per minute at a depth of 0.5 inches of water. Other exemplary sparse cloth materials are provided below.

[0174] In an exemplary embodiment, the electrostatically charged filter media may include Technostat (Hollingsworth & Vose, East Walpole, Massachusetts) or Technostat Plus (Hollingsworth & Vose, East Walpole, Massachusetts).

[0175] Fine fiber layer

[0176] Each fiber layer may include a continuous fiber layer, such as that described in the continuous fiber section of part F.

[0177] support layer

[0178] The filter media includes a support layer (also known as "sparse cloth").

[0179] Any suitable support layer can be used.

[0180] In some embodiments, the support layer preferably has a relatively high air permeability and / or a relatively low basis weight.

[0181] The support layer may comprise or be made of any suitable porous material. In some embodiments, the support layer may preferably be a polymer.

[0182] Examples of suitable materials for the support layer include spunbond, wet-laid, carded, or meltblown nonwoven materials or combinations thereof, including, for example, spunbond-meltblown-spunbond materials. The fibers can be in woven or nonwoven form. Examples of synthetic nonwovens include polyester nonwovens, nylon nonwovens, polyolefin (e.g., polypropylene) nonwovens, polycarbonate nonwovens, or blends or multicomponent nonwovens thereof. Sheet-like support layers (e.g., cellulose webs, synthetic webs, and / or glass webs or composite webs) are typical examples of filter support layers. Other examples of suitable support layers include polyester or bicomponent polyester fibers or polypropylene / polyethylene terephthalate, or polyethylene / polyethylene terephthalate bicomponent fibers in spunbond fabrics.

[0183] In some embodiments, the support layer comprises multiple fibers or strands. The fibers or strands of the support layer may be continuous or discontinuous. Continuous fibers (e.g., strands) are made by “continuous” fiber-forming processes, such as meltblown, melt spinning, extrusion, woven yarn, loosely woven fabric, and / or spunbond processes, and typically have a longer length than discontinuous fibers, as described in more detail below. Discontinuous fibers are, for example, short fibers that are typically cut (e.g., from filaments) or formed into discontinuous discrete fibers having a specific length or length range.

[0184] In some embodiments, the multiple fibers or strands of the support layer comprise synthetic fibers or strands (e.g., synthetic polymer fibers or strands). The synthetic fibers or strands of the support layer may be continuous fibers. Non-limiting examples of suitable synthetic fibers / strands include polyesters, polyaramids, polyimides, polyolefins (e.g., polyethylene, such as high-density polyethylene, low-density polyethylene, and / or linear low-density polyethylene), ethylene-vinyl acetate, polyacrylamide, polylactic acid, polypropylene, Kevlar, Nomex, halogenated polymers (e.g., polyethylene terephthalate), acrylic resins, polyphenylene ether, polyphenylene sulfide, thermoplastic elastomers (e.g., thermoplastic polyurethane), polymethylpentene, and combinations thereof.

[0185] In some embodiments, the average pore size of the support layer is 100 micrometers or less, and typically at least 0.5 micrometers.

[0186] In some embodiments, the porosity of the supporting loose fabric is 20% or greater, and typically does not exceed 90%.

[0187] Exemplary support layers include those available from Midwest Filtration, Cincinnati, Ohio, under the trademarks FINON C303NW and FINON C3019 NW, or those available under the trademark CEREX 23200 (Cerex Advanced Fabrics, Inc., Cantoment, Florida). CEREX 23200 comprises nylon 6,6 with a thickness of 8.4 mils (0.21 mm) and a density of 67.8 g / m². 2 Basis weight, 28% solidity, and transmittance / solidity of 615.1. The pore size of CEREX 23200 is shown in Table 8. Other exemplary loosely woven fabric materials are described, for example, in U.S. Patent Publication 2009 / 0120868.

[0188] Part C. Filter media consisting of two fine fiber layers and two loosely woven fabrics.

[0189] In other respects, this disclosure describes a filter medium comprising two fine fiber layers and two support layers. Figure 2G 。

[0190] In some embodiments, each sparse fabric includes a first main surface and a second main surface, and one main surface of each sparse fabric is adjacent to the microfiber layer. In some embodiments, one main surface of each support layer is preferably in contact with the microfiber layer.

[0191] The microfiber layer may include any microfiber layer or microfiber layer features described in Part B of this disclosure.

[0192] The support layer may include any of the support layers or features of the support layer described in Part B of this disclosure.

[0193] Part D. Glass-free filter media

[0194] In one aspect, this disclosure describes a preferably glass-free filter medium. The filter medium is a nonwoven filter medium.

[0195] In some embodiments, the filter medium may include the filter medium as described in the application filed on the same day entitled “FILTRATIONMEDIA [Filter Medium]” with Agent’s Case No. 0444.000118WO01.

[0196] In some embodiments, the nonwoven filter media includes: bicomponent fibers, a first fiber comprising polyethylene terephthalate (PET) and having a fiber diameter of 0.1 micrometer to 1 micrometer, a second fiber comprising PET and having a fiber diameter of 1 micrometer to 5 micrometers, and microfibrillated fibers.

[0197] In an exemplary embodiment, the nonwoven filter medium comprises: 25 wt% to 75 wt% of bicomponent fibers having a fiber diameter of 5 micrometers to 25 micrometers and a fiber length of 0.1 cm to 15 cm; 10 wt% to 50 wt% of a first fiber comprising polyethylene terephthalate (PET) and having a fiber diameter of 0.1 micrometers to 1 micrometer; and 10 wt% to 25 wt% of a second fiber comprising PET and having a fiber diameter of 1 micrometer to 5 micrometers; and 10 wt% to 25 wt% of microfibrillated fibers, wherein most of the microfibrillated fibers have a transverse dimension of up to 4 micrometers.

[0198] In some embodiments, one or more fibers are selected or treated to alter the electrostatic charge of the medium. Charge typically includes layers of positive or negative charges trapped at or near the polymer surface, or a charge cloud stored within the polymer bulk. Charge may also include polarization charges that are frozen when the dipoles of the molecules align. Methods for subjecting materials to charge are well known to those skilled in the art. These methods include, for example, thermal methods, liquid contact methods, electron beam methods, plasma methods, and corona discharge methods.

[0199] bicomponent fibers

[0200] The filter media comprises bicomponent fibers. Any suitable bicomponent fibers may be used, and the bicomponent fibers include any bicomponent fibers (or combinations thereof) described in the bicomponent fiber section of Part A of this disclosure.

[0201] Small efficiency fiber

[0202] The filter media includes “small efficiency fibers”, where “small efficiency fibers” as used herein are fibers having a fiber diameter of at least 0.1 micrometers and less than 1 micrometer.

[0203] In some embodiments, the low-efficiency fiber is preferably PET fiber. In some embodiments, the low-efficiency fiber may be composed substantially of PET. In some embodiments, the low-efficiency fiber may be composed of PET.

[0204] Alternatively or alternatively, low-efficiency fibers may include nylon, acrylic acid, rayon, polypropylene, polyethylene, ethylene vinyl alcohol (EVOH), polylactic acid (PLA), polyvinyl alcohol (PVA), polyvinyl chloride (PVC), polytetrafluoroethylene (PTFE) or other suitable meltable polymers.

[0205] In some embodiments, the filter media comprises at least 5 wt%, at least 10 wt%, at least 15 wt%, at least 20 wt%, at least 25 wt%, at least 30 wt%, at least 35 wt%, at least 40 wt%, or at least 45 wt% of low-efficiency fibers. In some embodiments, the filter media comprises up to 15 wt%, up to 20 wt%, up to 25 wt%, up to 30 wt%, up to 35 wt%, up to 40 wt%, up to 45 wt%, up to 50 wt%, or up to 55 wt% of low-efficiency fibers. In an exemplary embodiment, the filter media comprises 5 wt% to 50 wt% of low-efficiency fibers. In another exemplary embodiment, the filter media comprises 10 wt% to 50 wt% of low-efficiency fibers. In yet another exemplary embodiment, the filter media comprises 10 wt% to 40 wt% of low-efficiency fibers. In another exemplary embodiment, the filter medium comprises 10 wt% to 25 wt% low-efficiency fibers.

[0206] In some embodiments, the low-efficiency fiber has a fiber diameter of at least 0.1 micrometer, at least 0.2 micrometer, at least 0.3 micrometer, at least 0.4 micrometer, at least 0.5 micrometer, at least 0.6 micrometer, or at least 0.7 micrometer. In some embodiments, the low-efficiency fiber has a fiber diameter of up to 0.7 micrometer, up to 0.8 micrometer, up to 0.9 micrometer, or less than 1 micrometer. For example, in an exemplary embodiment, the low-efficiency fiber has a fiber diameter of at least 0.4 micrometer and less than 1 micrometer. In another exemplary embodiment, the low-efficiency fiber has a fiber diameter in the range of 0.6 micrometer to 0.8 micrometer. In another exemplary embodiment, the low-efficiency fiber has a fiber diameter of 0.7 micrometer.

[0207] In the example, the low-efficiency fiber is a PET fiber with a fiber diameter of 0.7 micrometers.

[0208] In some embodiments, the low-efficiency fiber has a length of at least 0.5 mm, at least 1 mm, or at least 1.5 mm. In some embodiments, the low-efficiency fiber has a length of up to 10 mm, up to 11 mm, up to 12 mm, or up to 15 mm. In an exemplary embodiment, the low-efficiency fiber has a length in the range of 1 mm to 15 mm. In another exemplary embodiment, the low-efficiency fiber has a length in the range of 1 mm to 12 mm.

[0209] In some embodiments, when the low-efficiency fiber comprises PET, the PET of the low-efficiency fiber preferably has a melting point of at least 250°C, more preferably at least 275°C, and even more preferably at least 290°C.

[0210] High-efficiency fibers

[0211] The filter media further includes “high-efficiency fibers”, wherein, as used herein, “high-efficiency fibers” are fibers with a diameter in the range of 1 to 5 micrometers.

[0212] In some embodiments, the high-efficiency fiber is preferably PET fiber. In some embodiments, the high-efficiency fiber may be substantially composed of PET. In some embodiments, the high-efficiency fiber may be composed of PET.

[0213] Alternatively or alternatively, high-efficiency fibers may include nylon, acrylic acid, rayon, polypropylene, polyethylene, ethylene vinyl alcohol (EVOH), polylactic acid (PLA), polyvinyl alcohol (PVA), polyvinyl chloride (PVC), polytetrafluoroethylene (PTFE) or other suitable meltable polymers.

[0214] In some embodiments, the filter media comprises at least 10 wt%, at least 15 wt%, at least 20 wt%, at least 25 wt%, or at least 30 wt%. In some embodiments, the filter media comprises up to 15 wt%, up to 20 wt%, up to 25 wt%, up to 30 wt%, up to 35 wt%, up to 40 wt%, up to 45 wt%, or up to 50 wt%. In an exemplary embodiment, the filter media comprises 10 wt% to 50 wt% of high-efficiency fibers. In another exemplary embodiment, the filter media comprises 10 wt% to 40 wt% of high-efficiency fibers. In yet another exemplary embodiment, the filter media comprises 10 wt% to 25 wt% of high-efficiency fibers.

[0215] In some embodiments, the high-efficiency fiber has a fiber diameter of at least 1 micrometer, at least 1.5 micrometers, at least 2 micrometers, at least 3 micrometers, or at least 4 micrometers. In some embodiments, the high-efficiency fiber has a fiber diameter of up to 1.5 micrometers, up to 2 micrometers, up to 3 micrometers, up to 4 micrometers, or up to 5 micrometers. For example, in an exemplary embodiment, the high-efficiency fiber has a fiber diameter in the range of 2 micrometers to 4 micrometers. In another exemplary embodiment, the high-efficiency fiber has a fiber diameter in the range of 2 micrometers to 3 micrometers. In yet another exemplary embodiment, the high-efficiency fiber has a fiber diameter of 2.5 micrometers. In yet another exemplary embodiment, the high-efficiency fiber has a fiber diameter of 2.7 micrometers.

[0216] In the example, the low-efficiency fiber is a PET fiber with a fiber diameter of 2.7 micrometers.

[0217] In some embodiments, the high-efficiency fiber has a length of at least 0.5 mm, at least 1 mm, or at least 1.5 mm. In some embodiments, the high-efficiency fiber has a length of up to 10 mm, up to 11 mm, up to 12 mm, or up to 15 mm. In an exemplary embodiment, the high-efficiency fiber has a length in the range of 1 mm to 15 mm. In another exemplary embodiment, the high-efficiency fiber has a length in the range of 1 mm to 12 mm.

[0218] In some embodiments, when the high-efficiency fiber includes PET, the PET of the high-efficiency fiber preferably has a melting point of at least 250°C, more preferably at least 275°C, and even more preferably at least 290°C.

[0219] Microfiber

[0220] Nonwoven filter media include microfibers. Any suitable microfiber can be used, and the microfiber can be any of those described in the microfiber section of Part A of this disclosure.

[0221] Characteristics of nonwoven filter media

[0222] In some embodiments, the nonwoven filter media has a solidity of at least 2%, at least 3%, at least 4%, at least 5%, at least 6%, at least 7%, at least 8%, at least 9%, or at least 10%. In some embodiments, the nonwoven filter media has a solidity of up to 5%, up to 6%, up to 7%, up to 8%, up to 9%, up to 10%, up to 11%, up to 12%, up to 13%, up to 14%, up to 15%, up to 16%, up to 17%, up to 18%, up to 19%, or up to 20%. In exemplary embodiments, the nonwoven filter media has a solidity in the range of 5% to 15%. In some embodiments, the solidity is preferably measured as described in the examples.

[0223] In some embodiments, the nonwoven filter media has a density of at least 20 g / m². 2 ), at least 24 g / m 2 At least 25 g / m 2 At least 30 g / m 2 At least 35 g / m 2 At least 40 g / m 2 At least 50 g / m 2 At least 60 g / m 2 Or at least 70g / m 2 The basis weight. In some embodiments, the nonwoven filter media has a basis weight of up to 25 g / m³. 2 Up to 30 g / m 2 Up to 35 g / m 2 Up to 40 g / m 2 Up to 50 g / m 2 Up to 60 g / m 2 Up to 70 g / m 2 Up to 75 g / m 2 Up to 80 g / m 2 Up to 85 g / m 2 Up to 90 g / m 2 Up to 95 g / m 2 Up to 100 g / m 2 or up to 105 g / m 2 The basis weight. In an exemplary embodiment, the nonwoven filter media has a basis weight of 24 g / m³. 2 Up to 100 g / m 2 Basis weight within the range. In some embodiments, ASTM D646-13 is preferably used to measure the basis weight.

[0224] In some embodiments, the nonwoven filter medium has a pore size of at least 0.5 micrometers, at least 1 micrometer, at least 1.5 micrometers, at least 2 micrometers, at least 3 micrometers, at least 5 micrometers, or at least 10 micrometers. In some embodiments, the nonwoven filter medium has a pore size of up to 5 micrometers, up to 10 micrometers, up to 15 micrometers, or up to 20 micrometers. In an exemplary embodiment, the nonwoven filter medium has a pore size from 0.5 micrometers to 20 micrometers. In an exemplary embodiment, the nonwoven filter medium has a pore size from 2 micrometers to 15 micrometers. As used herein, pore size refers to the average flow pore size, calculated as described in ASTM F316-03.

[0225] In some embodiments, the nonwoven filter media has a P95 / P50 ratio of at least 1.5 or at least 2. In some embodiments, the nonwoven filter media has a P95 / P50 ratio of up to 3.

[0226] In some embodiments, the nonwoven filter media has a thickness of at least 0.1 mm, at least 0.12 mm, at least 0.15 mm, or at least 0.2 mm. In some embodiments, the nonwoven filter media has a thickness of up to 0.2 mm, up to 0.4 mm, up to 0.5 mm, up to 0.7 mm, or up to 1 mm. In some embodiments, the thickness of the filter media is preferably measured using a foot pressure of 1.5 psi according to the TAPPIT 411 om-15 test method.

[0227] In some embodiments, the nonwoven filter media has a minimum depth of 1 ft at 0.5 inches of water. 3 / ft 2 / min, at least 5 ft underwater at 0.5 inches. 3 / ft 2 / min, or at least 10 ft underwater at a depth of 0.5 inches. 3 / ft 2 / min transmittance. In some embodiments, the nonwoven filter media has a transmittance of up to 10 ft at 0.5 inches of water. 3 / ft 2 / min, up to 20 ft underwater at a depth of 0.5 inches. 3 / ft 2 / min, up to 50 ft at a depth of 0.5 inches. 3 / ft 2 / min, up to 75 ft underwater at a depth of 0.5 inches. 3 / ft 2 / min, or up to 100 ft at a depth of 0.5 inches underwater. 3 / ft 2The transmittance is / min. In an exemplary embodiment, the nonwoven filter media has a transmittance of 1 ft at 0.5 inches of water. 3 / ft 2 / min to 100 ft at 0.5 inches underwater 3 / ft 2 The transmittance is within the range of / min. In another exemplary embodiment, the nonwoven filter media has a transmittance of 10 ft at a depth of 0.5 inches underwater. 3 / ft 2 / min to 75 ft underwater at 0.5 inches 3 / ft 2 Transmittance within a range of / min. In some embodiments, air transmittance is preferably measured according to ASTM D737-18.

[0228] In some embodiments, the nonwoven filter media is substantially resin-free. In some embodiments, the nonwoven filter media does not include resin. In this invention, resin is typically used to maintain the spacing between the fibers in the filter media and to prevent media instability. However, resin can clog the pores in the filter media, thereby reducing the density of the filter media and thus shortening its lifespan.

[0229] Without being bound by theory, it is believed that combining microfibrillated fibers with high-efficiency fibers (with fiber diameters ranging from 1 to 5 micrometers) is particularly beneficial to allow for a substantially resin-free filter medium. Microfibrillated fibers are believed to provide greater tensile strength, thus helping to maintain fiber spacing. Furthermore, high-efficiency fibers are believed to provide a more uniform pore structure.

[0230] In some embodiments, the nonwoven filter media comprises bicomponent fibers ranging from 25 wt% to 85 wt%. Using less than 25 wt% bicomponent fibers is expected to result in insufficient strength of the media, as the adhesive portion of the bicomponent fibers helps to hold the media together during use. Using more than 85 wt% bicomponent fibers will result in the media not having enough other fibers to provide the required efficiency and uniform structure.

[0231] In some embodiments, the nonwoven filter media includes a small amount of low-efficiency fibers (having a fiber diameter of at least 0.1 micrometers and less than 1 micrometer) ranging from 5 wt% to 50 wt%. Using less than 5 wt% of low-efficiency fibers typically results in the media failing to provide the required efficiency (e.g., a β value greater than 10). 4µm Using more than 50 wt% of low-efficiency fibers will increase pressure drop and will generally result in a weaker medium because the fibers are not in contact with another fiber that will help keep them in the medium.

[0232] In some embodiments, the nonwoven filter media includes a quantity of high-efficiency fibers (with fiber diameters ranging from 1 micrometer to 5 micrometers) ranging from 10 wt% to 50 wt%. Using less than 10 wt% of high-efficiency fibers typically results in media with irregular pore sizes. Using more than 50 wt% of high-efficiency fibers typically results in media that does not contain enough low-efficiency fibers to achieve the desired efficiency or enough bicomponent fibers to provide the required strength during use.

[0233] In some embodiments, the nonwoven filter media includes microfibrillated fibers in an amount ranging from 5 wt% to 25 wt%. Using less than 5 wt% of microfibrillated fibers typically results in insufficient strength and inefficiency of the media during use. Using more than 25 wt% of microfibrillated fibers typically results in irregular pore sizes (as indicated by a high P95 / P50 ratio).

[0234] In the past, low-melting-point PET fibers were sometimes used as a substitute for resin. However, these fibers melt during the manufacturing process of nonwoven filter media and, like resin, clog the pores in the filter media, thus reducing density and therefore lifespan.

[0235] Part E. Glass-free composite materials

[0236] In another aspect, this disclosure describes a composite material comprising a variety of nonwoven filter media. Each nonwoven filter media is preferably substantially glass-free or glass-free.

[0237] In some embodiments, the composite material may include the composite material as described in the application filed on the same day entitled “FILTRATION COMPOSITES” with Agent’s File No. 0444.000136WO01.

[0238] The composite material includes a first nonwoven filter medium, an optional second nonwoven filter medium, and a third nonwoven filter medium. The first nonwoven filter medium includes a first bicomponent fiber; a first high-efficiency fiber having a fiber diameter in the range of 1 micrometer to 5 micrometers; and a first microfibrillated fiber. The second nonwoven filter medium (if present) includes a second bicomponent fiber; a second high-efficiency fiber having a fiber diameter in the range of 1 micrometer to 5 micrometers; and a second microfibrillated fiber. The third nonwoven filter medium includes small-efficiency fibers having a fiber diameter of at least 0.1 micrometers and less than 1 micrometer. As used herein, a "high-efficiency fiber" is a fiber with a fiber diameter in the range of 1 micrometer to 5 micrometers. As used herein, a "small-efficiency fiber" is a fiber with a fiber diameter of at least 0.1 micrometers and less than 1 micrometer.

[0239] In some embodiments, the low-efficiency fiber preferably comprises polyethylene terephthalate (PET). In some embodiments, the first high-efficiency fiber preferably comprises PET. In some embodiments, the second high-efficiency fiber preferably comprises PET.

[0240] In some embodiments, one or more fibers or layers of the composite material may be selected or treated to alter the electrostatic charge of the medium. Charge typically includes layers of positive or negative charges trapped at or near the polymer surface, or a charge cloud stored in the polymer bulk. Charge may also include polarization charges that are frozen when the dipoles of the molecules align. Methods for subjecting materials to charge are well known to those skilled in the art. These methods include, for example, thermal methods, liquid contact methods, electron beam methods, plasma methods, and corona discharge methods.

[0241] In some embodiments, the composite material further includes a support layer.

[0242] In some embodiments, the first nonwoven filter medium, an optional second nonwoven filter medium (if present), and a third nonwoven filter medium are discrete layers. That is, there is no gradient between the first and second nonwoven filter media or between the second and third nonwoven filter media. If the second nonwoven filter medium is absent, there is no gradient between the first and third nonwoven filter media.

[0243] In some embodiments, the first nonwoven filter medium is in contact with the second nonwoven filter medium, and the second nonwoven filter medium is in contact with the third nonwoven filter medium. When the composite material further includes a support layer, the third nonwoven filter medium may be in contact with the support layer.

[0244] In some embodiments, the composite material is configured to allow liquid to pass through a first nonwoven filter medium, then through a second nonwoven filter medium, and then through a third nonwoven filter medium.

[0245] In some embodiments, when the composite material includes a support layer, the composite material is configured to allow liquid to pass through a first nonwoven filter medium, then through a second nonwoven filter medium, then through a third nonwoven filter medium, and then through the support layer.

[0246] In some embodiments, the first nonwoven filter medium is in contact with a third nonwoven filter medium. When the composite material further includes a support layer, the third nonwoven filter medium may be in contact with the support layer.

[0247] In some embodiments, the composite material is configured to allow liquid to pass through a first nonwoven filter medium and then through a third nonwoven filter medium. When the composite material further includes a support layer, the composite material is configured to allow liquid to pass through the first nonwoven filter medium, then through the third nonwoven filter medium, and then through the support layer.

[0248] In some embodiments, the composite material is substantially resin-free. In some embodiments, the composite material does not include resin.

[0249] In some embodiments, the composite material is substantially free of glass and includes, for example, glass fibers. In some embodiments, the composite material does not include glass.

[0250] In an exemplary embodiment, the composite material includes a first nonwoven filter medium, an optional second nonwoven filter medium, and a third nonwoven filter medium. The first nonwoven filter medium includes: 40 wt% to 90 wt% of a first bicomponent fiber having a fiber diameter in the range of 5 micrometers to 50 micrometers and a fiber length of 0.1 cm to 15 cm; 0 wt% to 25 wt% of a first high-efficiency fiber; and 10 wt% to 60 wt% of a first microfibrillated fiber, wherein most of the microfibrillated fibers have a transverse dimension of up to 4 micrometers. The optional second nonwoven filter medium includes: 40 wt% to 90 wt% of a second bicomponent fiber having a fiber diameter in the range of 5 micrometers to 50 micrometers and a fiber length of 0.1 cm to 15 cm; 0 wt% to 25 wt% of a second high-efficiency fiber; and 10 wt% to 60 wt% of a second microfibrillated fiber, wherein most of the microfibrillated fibers have a transverse dimension of up to 4 micrometers. The third type of nonwoven filter media includes low-efficiency fibers.

[0251] As described in Example 8, adding a 1 µm diameter electrospun fiber layer to the filter media composite increases the composite's efficiency compared to the composite without the fiber layer. This is further described in Example 9 and as... Figure 20C As shown, the fine fiber layer can be replaced by a layer comprising low-efficiency fine fibers, and the resulting composite material is expected to have similar efficiency to the composite material comprising the fine fiber layer.

[0252] The result in Example 8 is unexpected, as it has been previously reported that forming interfaces between media layers is undesirable, and gradient structures should be used instead. (See, for example, U.S. Publication No. 2014 / 0360145.) Unwilling to be bound by the 30 theory, it is believed that forming interfaces between media layers (including, for example, a nonwoven filter media layer having layers containing low-efficiency fine fibers and a filter media layer acting as a load layer) can allow for higher efficiency than using a gradient structure, because the non-uniformity of each layer is misaligned across the entire depth of the media.

[0253] First nonwoven filter media and second nonwoven filter media

[0254] The first nonwoven filter medium and the optional second nonwoven filter medium (if present) each comprise bicomponent fibers, high-efficiency fibers with a fiber diameter in the range of 1 micrometer to 5 micrometers, and microfibrillated fibers.

[0255] In some embodiments, either or both of the first and second nonwoven filter media act as a load layer, i.e., a filter media that distributes the locations of collected contaminants across the entire depth of the medium. Figure 20C An exemplary embodiment is described herein in which both the first and second nonwoven filter media serve as load layers. Figure 20B An exemplary embodiment is shown that does not include a second nonwoven filter.

[0256] In some embodiments, either or both of the first and second nonwoven filter media have a solidity of at least 2%, at least 3%, at least 4%, at least 5%, at least 6%, at least 7%, at least 8%, at least 9%, or at least 10%. In some embodiments, the nonwoven filter media have a solidity of up to 5%, up to 6%, up to 7%, up to 8%, up to 9%, up to 10%, up to 11%, up to 12%, up to 13%, up to 14%, up to 15%, up to 16%, up to 17%, up to 18%, up to 19%, or up to 20%. In an exemplary embodiment, the first nonwoven filter media has a solidity in the range of 5% to 15%. In an exemplary embodiment, the second nonwoven filter media has a solidity in the range of 5% to 15%. In some embodiments, the solidity is preferably measured as described in the methods of Examples 5 to 9.

[0257] In some embodiments, either or both of the first nonwoven filter medium and the second nonwoven filter medium have a concentration of at least 20 g / m³. 2 At least 24 g / m 2 At least 25 g / m 2 At least 30 g / m 2At least 35 g / m 2 At least 40 g / m 2 At least 50 g / m 2 At least 60 g / m 2 Or at least 70 g / m 2 The basis weight. In some embodiments, the nonwoven filter media has a basis weight of up to 25 g / m³. 2 Up to 30 g / m 2 Up to 35 g / m 2 Up to 40 g / m 2 Up to 50 g / m 2 Up to 60 g / m 2 Up to 70 g / m 2 Up to 75 g / m 2 Up to 80 g / m 2 Up to 85 g / m 2 Up to 90 g / m 2 Up to 95 g / m 2 Up to 100 g / m 2 or up to 105 g / m 2 The basis weight. In an exemplary embodiment, the first nonwoven filter medium has a basis weight of 24 g / m³. 2 Up to 100 g / m 2 The basis weight is within the range. In an exemplary embodiment, the second nonwoven filter medium has a basis weight of 24 g / m³. 2 Up to 100 g / m 2 Basis weight within the range. In some embodiments, ASTM D646-13 is preferably used to measure the basis weight.

[0258] In some embodiments, either or both of the first and second nonwoven filter media have a pore size of at least 0.5 micrometers, at least 1 micrometer, at least 1.5 micrometers, at least 2 micrometers, at least 3 micrometers, at least 5 micrometers, or at least 10 micrometers. In some embodiments, the nonwoven filter media have a pore size of up to 5 micrometers, up to 10 micrometers, up to 15 micrometers, or up to 20 micrometers. In an exemplary embodiment, the first nonwoven filter media has a pore size of 0.5 micrometers to 20 micrometers. In an exemplary embodiment, the second nonwoven filter media has a pore size of 0.5 micrometers to 20 micrometers. In another exemplary embodiment, the first nonwoven filter media has a pore size of 2 micrometers to 15 micrometers. In another exemplary embodiment, the second nonwoven filter media has a pore size of 2 micrometers to 15 micrometers. As used herein, pore size refers to the average flow pore size, calculated as described in ASTM F316-03.

[0259] In some embodiments, either or both of the first and second nonwoven filter media have a thickness of at least 0.1 mm, at least 0.12 mm, at least 0.15 mm, or at least 0.2 mm. In some embodiments, the nonwoven filter media have a thickness of up to 0.2 mm, up to 0.4 mm, up to 0.5 mm, up to 0.7 mm, or up to 1 mm. In an exemplary embodiment, the first nonwoven filter media has a thickness in the range of 0.12 mm to 1 mm. In an exemplary embodiment, the second nonwoven filter media has a thickness in the range of 0.12 mm to 1 mm. In some embodiments, the thickness of the filter media is preferably measured using a foot pressure of 1.5 psi according to the TAPPI T411 om-15 test method.

[0260] In some embodiments, either or both of the first and second nonwoven filter media have a minimum depth of 1 ft at 0.5 inches of water. 3 / ft 2 / min, with at least 5 ft at 0.5 inches underwater. 3 / ft 2 / min, or at least 10 ft underwater at a depth of 0.5 inches. 3 / ft 2 / min transmittance. In some embodiments, the nonwoven filter media has a transmittance of up to 10 ft at 0.5 inches of water. 3 / ft 2 / min, up to 20 ft underwater at a depth of 0.5 inches. 3 / ft 2 / min, up to 50 ft at a depth of 0.5 inches. 3 / ft 2 / min, up to 75 ft underwater at a depth of 0.5 inches. 3 / ft 2 / min, or up to 100ft underwater at a depth of 0.5 inches. 3 / ft 2 The transmittance is / min. In an exemplary embodiment, the first nonwoven filter medium has a transmittance of 1 ft at 0.5 inches of water. 3 / ft 2 / min to 0.5 inches underwater at 100 ft 3 / ft 2 The transmittance is within the range of / min. In an exemplary embodiment, the second nonwoven filter medium has a transmittance of 1 ft at 0.5 inches of water. 3 / ft 2 / min to 0.5 inches underwater at 100 ft 3 / ft 2The transmittance is within the range of / min. In another exemplary embodiment, the first nonwoven filter medium has a transmittance of 10 ft at 0.5 inches of water. 3 / ft 2 / min to 0.5 inches underwater 75 ft 3 / ft 2 The transmittance is within the range of / min. In another exemplary embodiment, the second nonwoven filter media has a transmittance of 10 ft at 0.5 inches of water. 3 / ft 2 / min to 0.5 inches underwater 75 ft 3 / ft 2 Transmittance within a range of / min. In some embodiments, air transmittance is preferably measured according to ASTM D737-18.

[0261] In some embodiments, either or both of the first nonwoven filter medium and the second nonwoven filter medium are substantially resin-free. In some embodiments, either or both of the first nonwoven filter medium and the second nonwoven filter medium do not contain resin.

[0262] In some embodiments, either or both of the first nonwoven filter medium and the second nonwoven filter medium are substantially free of glass fibers. In some embodiments, either or both of the first nonwoven filter medium and the second nonwoven filter medium do not contain glass fibers.

[0263] bicomponent fibers

[0264] The first and second filter media each comprise bicomponent fibers. Any suitable bicomponent fiber can be used in each filter media, and the bicomponent fiber can be selected according to the intended use of the media. Each bicomponent fiber can be any of those described in the bicomponent fiber section of Part A of this disclosure.

[0265] High-efficiency fibers

[0266] The first and second filter media may each include "high-efficiency fibers," wherein, as used herein, "high-efficiency fibers" are fibers with a diameter in the range of 1 to 5 micrometers. In some embodiments, one or both of the first and second filter media may not include high-efficiency fibers.

[0267] In some embodiments, the high-efficiency fiber is preferably PET fiber. In some embodiments, the high-efficiency fiber may be substantially composed of PET. In some embodiments, the high-efficiency fiber may be composed of PET.

[0268] Alternatively or alternatively, low-efficiency fibers may include nylon, acrylic acid, rayon, polypropylene, polyethylene, ethylene vinyl alcohol (EVOH), polylactic acid (PLA), polyvinyl alcohol (PVA), polyvinyl chloride (PVC), polytetrafluoroethylene (PTFE) or other suitable meltable polymers.

[0269] In some embodiments, each of the first and second filter media comprises at least 0 wt%, at least 0.1 wt%, at least 1 wt%, at least 5 wt%, at least 10 wt%, at least 15 wt%, at least 20 wt%, or at least 25 wt% high-efficiency fibers. In some embodiments, each of the first and second filter media comprises up to 15 wt%, up to 20 wt%, or up to 25 wt% high-efficiency fibers. In an exemplary embodiment, the first filter media comprises 0 wt% to 25 wt% high-efficiency fibers. In an exemplary embodiment, the second filter media comprises 0 wt% to 25 wt% high-efficiency fibers. In another exemplary embodiment, the first filter media comprises 10 wt% to 25 wt% high-efficiency fibers. In another exemplary embodiment, the second filter media comprises 10 wt% to 25 wt% high-efficiency fibers.

[0270] In some embodiments, the high-efficiency fiber has a fiber diameter of at least 1 micrometer, at least 1.5 micrometers, at least 2 micrometers, at least 3 micrometers, or at least 4 micrometers. In some embodiments, the high-efficiency fiber has a fiber diameter of up to 1.5 micrometers, up to 2 micrometers, up to 3 micrometers, up to 4 micrometers, or up to 5 micrometers. For example, in an exemplary embodiment, the high-efficiency fiber has a fiber diameter in the range of 2 micrometers to 4 micrometers. In another exemplary embodiment, the high-efficiency fiber has a fiber diameter of 2.7 micrometers. In another exemplary embodiment, the high-efficiency fiber has a fiber diameter of 2.5 micrometers.

[0271] In the example, the high-efficiency fiber comprises PET and has a fiber diameter of 2.7 micrometers.

[0272] In some embodiments, the high-efficiency fiber has a length of at least 0.5 mm, at least 1 mm, or at least 1.5 mm. In some embodiments, the high-efficiency fiber has a length of up to 10 mm, up to 11 mm, up to 12 mm, or up to 15 mm. In an exemplary embodiment, the high-efficiency fiber has a length in the range of 1 mm to 15 mm. In another exemplary embodiment, the high-efficiency fiber has a length in the range of 1 mm to 12 mm.

[0273] In some embodiments, when the high-efficiency fiber comprises PET, the PET has a melting point of at least 250°C, more preferably at least 275°C, and even more preferably at least 290°C.

[0274] Microfiber

[0275] The first and second filter media each comprise microfibrils. Any suitable microfibrils may be used, and the microfibrils may be any of those described in the microfibrils section of Part A of this disclosure.

[0276] Third nonwoven filter media

[0277] The third nonwoven filter media includes “small efficiency fibers”, wherein, as used herein, “small efficiency fibers” are fibers having a fiber diameter of at least 0.1 micrometers and less than 1 micrometer.

[0278] In some embodiments, the low-efficiency fiber preferably comprises PET. In some embodiments, the low-efficiency fiber may be substantially composed of PET. In some embodiments, the low-efficiency fiber may be composed of PET.

[0279] Alternatively or alternatively, low-efficiency fibers may include nylon, acrylic acid, rayon, polypropylene, polyethylene, ethylene vinyl alcohol (EVOH), polylactic acid (PLA), polyvinyl alcohol (PVA), polyvinyl chloride (PVC), polytetrafluoroethylene (PTFE) or other suitable meltable polymers.

[0280] In some embodiments, the third nonwoven filter media may include fibers and components other than low-efficiency fibers. These additional fibers and components may include bicomponent fibers, monocomponent heat-fusible fibers, resins, etc.

[0281] When the third nonwoven filter media may include fibers and components other than low-efficiency fibers, the third nonwoven filter media preferably includes at least 10 wt%, at least 15 wt%, at least 20 wt%, at least 25 wt%, at least 30 wt%, at least 35 wt%, at least 40 wt%, or at least 45 wt% of low-efficiency fibers. In some embodiments, the third nonwoven filter media includes up to 15 wt%, up to 20 wt%, up to 25 wt%, up to 30 wt%, up to 35 wt%, up to 40 wt%, up to 45 wt%, or up to 50 wt% of low-efficiency fibers.

[0282] In some embodiments, the low-efficiency fiber has a fiber diameter of at least 0.1 micrometer, at least 0.2 micrometer, at least 0.3 micrometer, at least 0.4 micrometer, at least 0.5 micrometer, at least 0.6 micrometer, or at least 0.7 micrometer. In some embodiments, the low-efficiency fiber has a fiber diameter of up to 0.7 micrometer, up to 0.8 micrometer, up to 0.9 micrometer, or less than 1 micrometer. For example, in an exemplary embodiment, the low-efficiency fiber has a fiber diameter of at least 0.4 micrometer and less than 1 micrometer. In another exemplary embodiment, the low-efficiency fiber has a fiber diameter in the range of 0.6 micrometer to 0.8 micrometer. In another exemplary embodiment, the low-efficiency fiber has a fiber diameter of 0.7 micrometer (700 nm).

[0283] In some embodiments, the low-efficiency fiber has a length of at least 0.5 mm, at least 1 mm, or at least 1.5 mm. In some embodiments, the low-efficiency fiber has a length of up to 10 mm, up to 11 mm, up to 12 mm, or up to 15 mm. In an exemplary embodiment, the low-efficiency fiber has a length in the range of 1 mm to 15 mm. In another exemplary embodiment, the low-efficiency fiber has a length in the range of 1 mm to 12 mm.

[0284] In one exemplary embodiment, the low-efficiency fiber is a PET fiber with a fiber diameter of 0.7 micrometers.

[0285] In some embodiments, when the low-efficiency fiber comprises PET, the PET of the low-efficiency fiber has a melting point of at least 250°C, more preferably at least 275°C, and even more preferably at least 290°C.

[0286] support layer

[0287] In some embodiments, the composite material includes a support layer (also referred to as a loose fabric). Any suitable support layer can be used. In some embodiments, the support layer includes any of the support layers or features of support layers described in the support layer section of Part B of this disclosure.

[0288] Preparation of glass-free composite materials

[0289] On the other hand, this disclosure describes a method for manufacturing glass-free composite materials as described herein.

[0290] In some embodiments, the first nonwoven filter medium and the second nonwoven filter medium can be manufactured independently. In some embodiments, the first nonwoven filter medium and the third nonwoven filter medium can be manufactured independently. In some embodiments, the second nonwoven filter medium and the third nonwoven filter medium can be manufactured independently. In some embodiments, the first nonwoven filter medium, the second nonwoven filter medium, and the third nonwoven filter medium can be manufactured independently.

[0291] In some embodiments, at least one of the first nonwoven filter media, the second nonwoven filter media, and the third nonwoven filter media is formed using a wet web forming process.

[0292] In some embodiments, a method of manufacturing a composite material includes placing a first nonwoven filter medium in contact with a second nonwoven filter medium, or placing the second nonwoven filter medium in contact with a third nonwoven filter medium, or both placing the first nonwoven filter medium in contact with the second nonwoven filter medium and placing the second nonwoven filter medium in contact with the third nonwoven filter medium.

[0293] When the composite material includes a support layer, the method may further include placing a third nonwoven filter medium in contact with the support layer. In some embodiments, the method may include forming the third nonwoven filter medium on the support layer.

[0294] In some embodiments, a method of manufacturing the composite material includes bonding a first nonwoven filter medium to a second nonwoven filter medium, or bonding the second nonwoven filter medium to a third nonwoven filter medium, or both bonding the first nonwoven filter medium to the second nonwoven filter medium and bonding the second nonwoven filter medium to the third nonwoven filter medium. Any suitable bonding means can be used, including, for example, lamination.

[0295] F. Filter media including continuous fine fibers

[0296] In one aspect, this disclosure describes a filter medium comprising a support layer and a continuous layer of fine fibers. (See also...) Figure 21A In some embodiments, a continuous layer of fine fibers is located upstream of the support layer. The filter medium may further include an efficiency layer. (See...) Figure 21A and Figure 21C The filter media are further described below and in some embodiments may include the filter media described in co-pending application PCT / US2020 / 054837 or co-pending application PCT / US2020 / 054844.

[0297] In some embodiments, a continuous fine fiber layer is located between the efficiency layer and the support layer, and the efficiency layer is located upstream of the filter medium.

[0298] In some embodiments, the continuous fine fiber layer acts as a surface loading layer. In some embodiments, the efficiency layer acts as a depth loading layer.

[0299] On the other hand, this disclosure describes a filter medium comprising a continuous layer of fine fibers and two efficiency layers. (See also...) Figure 21D In some embodiments, the continuous fiber layer is located between two efficiency layers.

[0300] In some embodiments, the filter medium may include a plurality of continuous microfiber layers and / or a plurality of efficiency layers. For example, in one embodiment, the filter medium may include a first efficiency layer located upstream of the filter medium, a first continuous microfiber layer located downstream of the first efficiency layer, a second efficiency layer located downstream of the first continuous microfiber layer, and a second microfiber layer located downstream of the second efficiency layer. A support layer will typically be located downstream of the most downstream continuous microfiber layer. (See also...) Figure 21B (Left side diagram.)

[0301] For example, in another embodiment, the filter medium includes a first efficiency layer located upstream of the filter medium, a first continuous fiber layer located downstream of the first efficiency layer, a second efficiency layer located downstream of the first continuous fiber layer, a second fiber layer located downstream of the second efficiency layer, a third efficiency layer located downstream of the first continuous fiber layer, and a third fiber layer located downstream of the third efficiency layer. A support layer is typically located downstream of the most downstream continuous fiber layer. (See also...) Figure 21B (The image is divided into two parts.)

[0302] In some embodiments, the filter medium may include more than one efficiency layer located upstream of the filter medium and a continuous layer of fine fibers located downstream of the efficiency layers. (See also) Figure 21B (See right sub-figure.) One or more efficiency layers can be used, for example, to increase the capacity of the filter media (and thus its lifespan) or to improve pressure drop.

[0303] The filter media disclosed herein can minimize the adverse effects of flow rate changes on filter media efficiency without a corresponding increase in pressure drop, i.e., an increase in the pressure required to force the fluid through the filter media.

[0304] In some embodiments, the filter media described herein, comprising a support layer, an efficiency layer, and a continuous fiber layer, achieves improved efficiency without affecting the pressure drop compared to media comprising a support layer and an efficiency layer but without one or more continuous fiber layers. That is, the pressure drop of the filter media described herein is within 20%, more preferably within 15%, and most preferably within 10% of the pressure drop of media without one or more continuous fiber layers.

[0305] In some embodiments, the filter media described herein achieves equivalent efficiency but exhibits lower pressure drop compared to media without a continuous fiber layer.

[0306] The filter media described in this disclosure include a continuous fine fiber layer with high density (i.e., an efficiency layer acting as a deep loading layer) used in conjunction with a low-density medium. The continuous fine fiber layer can act as a surface loading layer, thereby preventing particles from passing through the medium. Additionally, because the continuous fine fiber layer is very thin, its pressure drop increases as much as that of a thicker medium.

[0307] In some embodiments, one or more fibers of the filter media may be selected or treated to alter the electrostatic charge of the filter media. Charge typically includes layers of positive or negative charges trapped at or near the polymer surface, or a charge cloud stored in the polymer bulk. Charge may also include polarization charges that are frozen when the dipoles of the molecules align. Methods for subjecting materials to charge are well known to those skilled in the art. These methods include, for example, thermal methods, liquid contact methods, electron beam methods, plasma methods, and corona discharge methods.

[0308] Average maximum pore size and average flow pore size of the composite material of support layer and continuous fine fiber layer

[0309] As described above, the filter media includes a support layer and a continuous fiber layer. In some embodiments, the continuous fiber layer may include multiple continuous fiber layers. These support layers and one or more continuous fiber layers may form a composite material. The composite material includes at least one continuous fiber layer.

[0310] In some embodiments, the filter media exhibits at least 1 ft of air permeability at 0.5 inches underwater, as measured according to ASTM D737-18, entitled "Test Method for Air Permeability of Textile Fabrics". 3 / ft 2 / min, at least 2 ft underwater at 0.5 inches. 3 / ft 2 / min, at least 5 ft underwater at 0.5 inches. 3 / ft 2 / min, at least 10 ft underwater at 0.5 inches. 3 / ft 2 / min, at least 15 ft underwater at 0.5 inches. 3 / ft 2 / min, or at least 20 ft underwater at a depth of 0.5 inches. 3 / ft 2 / min air transmittance (also known as Fraser air transmittance or airflow). In some embodiments, the nonwoven filter media exhibits up to 30 ft at 0.5 inches of water, as measured according to ASTM D737-18.3 / ft 2 / min, up to 50 ft at a depth of 0.5 inches. 3 / ft 2 / min, up to 100 ft at a depth of 0.5 inches. 3 / ft 2 / min, or up to 200 ft at 0.5 inches underwater. 3 / ft 2 / min air permeability. In an exemplary embodiment, the nonwoven filter media or composite material exhibits an air permeability of 1 ft at 0.5 inches of water. 3 / ft 2 / min to 100 ft at 0.5 inches underwater 3 / ft 2 Air permeability in the range of / min. In another exemplary embodiment, the nonwoven filter media or composite material exhibits air permeability in the range of 0.5 inches underwater at 2 ft. 3 / ft 2 / min to 30 ft underwater at 0.5 inches 3 / ft 2 Air permeability within the range of / min.

[0311] In some embodiments, the filter medium has a composite material average maximum pore size of up to 20 µm, preferably up to 15 µm, and more preferably up to 14 µm. In some embodiments, the composite material maximum pore size of the filter medium is at least 0.1 µm. As used herein, “composite material average maximum pore size” refers to the average maximum pore size of a composite material comprising a support layer and any continuous fine fiber layers present in layers adjacent to the support layer.

[0312] In some embodiments, the filter medium has a composite average flow pore size or P50 of up to 11 µm, preferably up to 9 µm, and more preferably up to 6 µm. In some embodiments, the composite average flow pore size or P50 of the filter medium is at least 0.1 µm. As used herein, “composite average flow pore size” refers to the average flow pore size of a composite material comprising a support layer and any continuous fine fiber layer present in layers adjacent to the support layer.

[0313] In some embodiments, the average maximum pore size and / or the average flow pore size of the composite material are preferably determined using capillary flow porosity measurement.

[0314] Unwilling to be bound by theory, it is believed that the average maximum pore size and the average flow pore size of composite materials depend on the diameter of the fine fibers, the relative amounts of small and large fine fibers, the morphology of the composite material (such as layered or mixed), and other factors.

[0315] In some embodiments, the composite material may have an average flow orifice diameter similar to that of the efficiency layer. For example, in some embodiments, the average flow orifice diameter (P50) of the composite material may be within 1%, 2%, 3%, 5%, 10%, 20%, 30%, 50%, 100%, or 200% of the average flow orifice diameter (P50) of the adjacent efficiency layer.

[0316] As described in Example 15, the average maximum pore size of the composite filter media may be related to the filter media's ability to withstand a pressure drop of at least 20 psi during liquid filtration, indicating better filtration performance than filter media that cannot withstand the same conditions. Although the performance of this filter media was characterized using liquid as described in the example, it is believed that the observed excellent performance can also be observed when tested with air.

[0317] In some embodiments, the average maximum pore size of the composite material of the filter media may be related to the filter media’s ability to withstand a pressure drop of at least 20 psi during liquid filtration, which indicates better filtration performance than filter media that cannot withstand the same conditions.

[0318] While the average maximum pore size of a composite filter medium may be related to its ability to withstand a pressure drop of at least 20 psi during liquid filtration, the average maximum pore size of the composite can sometimes provide inconsistent values ​​if the medium includes defects or unusually large maximum pores. Therefore, additional values, as described below, were also examined to better understand the pore size range and pore size distribution of the composite.

[0319] The P95 / P50 ratio of composite materials including a support layer and a continuous fine fiber layer

[0320] In some embodiments, the composite material formed by the support layer and the continuous fine fiber layer has a P95 / P50 ratio of up to 1.8, up to 1.9, or up to 2.

[0321] Although the pore size of the fine fiber layer controls most of the P95 / P50 ratio values ​​of the composite, the interaction between the support layer and the continuous fine fiber layer also affects the properties. Without being bound by theory, it is believed that these interactions make pore size measurements of the composite more informative than measurements of the pore size of the fine fiber layer alone.

[0322] The value of P50 reflects pores with a diameter of 50% or less through which fluid flows. The value of P95 reflects pores with a diameter of 95% or less through which fluid flows. A larger P95 / P50 ratio generally reflects a larger range of pore sizes and the presence of relatively large pores.

[0323] In some embodiments, the P95 / P50 ratio of the composite material is at least 1.

[0324] The P95 / P50 ratio of the efficiency layer adjacent to the fine fiber layer

[0325] In some embodiments, the efficiency layer has a P95 / P50 ratio of at least 1.8, at least 1.9, or at least 2.

[0326] Unwilling to be bound by theory, composites with a P95 / P50 ratio of less than 1.8 are believed to exhibit a density within a range that would be expected to lead to undesirably high pressure drops. Furthermore, since density increases as P95 / P50 decreases, the number of particles that may be trapped by the composite also decreases.

[0327] In some embodiments, the efficiency layer has a P95 / P50 ratio of up to 2.5, up to 3, up to 4, up to 5, up to 10, up to 15, or up to 20.

[0328] Unwilling to be bound by theory, a P95 / P50 ratio greater than 20 is expected to result in a medium layer with a larger pore size, and therefore too little pore size to capture the desired particle size (e.g., in the range of 1 µm to 100 µm).

[0329] For example, the efficiency stratum has a P95 / P50 ratio in the range of 1.8 to 20, in the range of 2 to 10, or in the range of 2 to 5.

[0330] In some embodiments, preferably, the maximum value of the range of P95 / P50 ratios including the composite material is equal to or lower than the minimum value of the range of P95 / P50 ratios including the efficiency layer. In some embodiments, preferably, the P95 / P50 ratio of the composite material is equal to or lower than the P95 / P50 ratio of the efficiency layer.

[0331] For example, in an exemplary embodiment, the P95 / P50 ratio of the composite material is up to 1.8, while the P95 / P50 ratio of the efficiency layer is at least 1.8. In another exemplary embodiment, the P95 / P50 ratio of the composite material is up to 1.9, and the P95 / P50 ratio of the efficiency layer is at least 1.9. In yet another exemplary embodiment, the P95 / P50 ratio of the composite material is up to 2, and the P95 / P50 ratio of the efficiency layer is at least 2.

[0332] In some embodiments, preferably, the maximum P95 / P50 ratio of the composite material is lower than the minimum P95 / P50 ratio of the efficiency layer. For example, in an exemplary embodiment, the P95 / P50 ratio of the composite material is up to 1.8, while the P95 / P50 ratio of the efficiency layer is at least 2. In another exemplary embodiment, the P95 / P50 ratio of the composite material is up to 1.9, and the P95 / P50 ratio of the efficiency layer is at least 2.

[0333] For example, in some embodiments, the P95 / P50 ratio of the efficiency layer adjacent to the fine fiber layer can be up to 1.5 times, up to 2 times, up to 3 times, up to 4 times, up to 5 times, up to 6 times, up to 7 times, up to 8 times, up to 9 times, or up to 10 times greater than the P95 / P50 ratio of the composite material.

[0334] Overlapping aperture distribution

[0335] In some embodiments, the pore size distribution of the efficiency layer overlaps with that of the composite material (including the support layer and the fiber layer). If the filter media includes more than one efficiency layer, the pore size distribution of the efficiency layer adjacent to the fiber layer overlaps with that of the composite material (including the support layer and the fiber layer). It is not desirable to be bound by theory, but this overlap of pore size distributions is believed to increase filter life.

[0336] When the pore size distribution of the efficiency layer and the composite material does not overlap (because the pore size of the composite material is smaller than that of the efficiency layer), the fine fiber layer traps particles of a size not trapped by the efficiency layer. This trapping leads to an increase in pressure drop and thus a shorter media lifetime.

[0337] If the pore size of the efficiency layer does not overlap with that of the composite material (since the pore size of the composite material is larger than that of the efficiency layer), the fine fiber layer will not provide the desired efficiency improvement.

[0338] Similarly, if the pore size of the efficiency layer and the pore size of the composite material overlap across their entire range, the fine fiber layer may not provide the desired efficiency improvement.

[0339] Therefore, in some embodiments, the P95 of the composite material preferably falls within the range provided by the P5 and P50 values ​​of the efficiency layer.

[0340] As shown in Example 16, when the P95 of the composite material drops below the range provided by the P5 and P50 values ​​of the efficiency layer adjacent to the fiber layer, the resulting pressure drop of the filter medium is high (23.2 kPa), which is more than 150% of the pressure drop of the filter medium excluding the fiber layer and the support layer.

[0341] Continuous fine fiber layer

[0342] The continuous fiber layer comprises continuous fibers with a diameter up to 10 micrometers (µm). In some embodiments, the continuous fiber layer comprises a single layer. In some embodiments, the continuous fiber layer comprises multiple layers. In some embodiments, when the continuous fiber layer comprises multiple layers, each layer may comprise continuous fibers with different diameters, or each layer may comprise different combinations of continuous fibers with different diameters.

[0343] In some embodiments, one or more continuous fine fiber layers serve as surface load layers.

[0344] In some embodiments, the continuous fine fibers may include fibers with a diameter of at least 0.05 µm (50 nm), at least 0.1 µm (100 nm), at least 0.15 µm, at least 0.2 µm, at least 0.25 µm, at least 0.3 µm, at least 0.35 µm, at least 0.4 µm, at least 0.45 µm, at least 0.5 µm, or at least 1 µm.

[0345] In some embodiments, the continuous fine fibers may include fibers with diameters up to 0.1 µm, up to 0.2 µm, up to 0.3 µm, up to 0.4 µm, up to 0.5 µm, up to 1.0 µm, up to 1.5 µm, up to 2 µm, up to 3 µm, up to 4 µm, up to 5 µm, up to 6 µm, up to 7 µm, up to 8 µm, up to 9 µm, or up to 10 µm.

[0346] For example, in an exemplary embodiment, the continuous microfiber may include fibers with a diameter in the range of 0.1 µm to 5 µm or in the range of 0.5 µm to 5 µm. In some embodiments (including, for example, when the continuous microfiber has an elliptical shape), the continuous microfiber may preferably include fibers with a diameter in the range of 1 µm to 5 µm. In some embodiments (including, for example, when the continuous microfiber does not include a mixture of fibers of different diameters), the continuous microfiber may include fibers with a diameter in the range of 0.2 µm to 1.5 µm.

[0347] In another exemplary embodiment, the continuous fine fibers may include fibers with a diameter ranging from 0.1 µm (100 nm) to 0.5 µm (500 nm). In another exemplary embodiment, the continuous fine fibers may include fibers with a diameter ranging from 0.2 µm (200 nm) to 0.3 µm (300 nm). In yet another exemplary embodiment, the continuous fine fibers may include fibers with a diameter ranging from 0.35 µm (350 nm) to 0.45 µm (450 nm).

[0348] In some embodiments, the continuous fine fibers may have an elliptical (including circular) shape. For example, the ratio of the major axis (width) to the minor axis (height) of the cross-section of the continuous fine fibers may be at least 2:1 (like, for example, lasagna) and up to 1:1 (like, for example, spaghetti).

[0349] In some embodiments, the diameter dimension of the continuous fiber is preferably in the range of 1 µm to 5 µm and the ratio of the major axis (width) to the minor axis (height) of the cross section is at least 1.5 : 1 and at most 1 : 1.

[0350] In some embodiments, the continuous fiber layer has a solidity of at least 10%, at least 11%, at least 12%, at least 13%, at least 14%, at least 15%, at least 20%, or at least 25%. In some embodiments, the continuous fiber layer has a solidity of up to 15%, up to 20%, up to 25%, up to 30%, up to 35%, or up to 40%. In exemplary embodiments, the continuous fiber layer has a solidity in the range of 15% to 30%. In some embodiments, the solidity of the continuous fiber layer is preferably calculated as described in the methods provided in Examples 10 to 14.

[0351] Fine fibers of mixed diameter

[0352] In some embodiments, continuous fine fibers may comprise a mixture of fibers of different diameters.

[0353] In some embodiments, the continuous microfiber may include two fibers of different diameters. When the continuous microfiber includes two fibers of different diameters, the ratio of the diameter of the "smaller" diameter fiber to the diameter of the "larger" diameter fiber (smaller fiber diameter:layer fiber diameter) may be in the range of 1:3 to 1:5, including, for example, 1:4. For example, in an exemplary embodiment, the continuous microfiber may include a first microfiber with a diameter in the range of 0.2 µm to 0.3 µm and a second microfiber with a diameter in the range of 0.9 µm to 1.1 µm. In another example, the smaller fiber diameter may be 0.25 µm and the larger fiber diameter may be 1 µm.

[0354] In embodiments where the continuous microfibers comprise a mixture of fibers of different diameters, the fibers of different diameters may be mixed or blended together within a single layer of the continuous microfiber layer.

[0355] In embodiments where the continuous fine fibers comprise a mixture of fibers of different diameters, the fibers of different diameters can form different layers within the continuous fine fiber layer. When fibers of different diameters form different layers within the continuous fine fiber layer, larger fibers can be deposited on the support before smaller fibers are deposited, thereby creating a gradient (including, for example, in terms of pore size and density) within the continuous fine fiber layer. Alternatively or additionally, when fibers of different diameters form different layers within the continuous fine fiber layer, larger and smaller fibers can be deposited to form multiple layers with different characteristics. Exemplary embodiments of this structure are described in... Figure 22A and Figures 22H to 22M As shown in the image.

[0356] In some embodiments, the "large" fine fibers have an average diameter of at least 600 nm, more preferably greater than 600 nm. In some embodiments, the "large" fine fibers have an average diameter of at least 700 nm, at least 800 nm, or at least 900 nm. In some embodiments, the "large" fine fibers preferably have an average diameter of at least 1000 nm (1 µm) or greater than 1000 nm (1 µm). The "large" fine fibers have an average diameter of up to 1100 nm, up to 1200 nm, up to 1300 nm, up to 1400 nm, up to 1500 nm, up to 2000 nm, up to 3000 nm, up to 4000 nm, up to 5000 nm (5 µm), or up to 10 µm. Exemplary images of a continuous fine fiber layer including large fine fibers deposited on a support layer are shown in [the image]. Figure 22B As shown in the image.

[0357] In embodiments in which the continuous microfiber layer comprises “large” microfibers and “small” microfibers, and wherein the average diameter of the large microfibers is at least three times the average fiber diameter of the small microfibers, the small microfibers may have an average diameter of up to 300 nm, up to 400 nm, up to 500 nm, or up to 600 nm. In some embodiments, the average fiber diameter of the small microfibers in the continuous microfiber layer may be at least 200 nm.

[0358] Properties of continuous fine fiber layers

[0359] In some embodiments, the continuous microfiber layer has an average flow orifice diameter of at least 0.1 µm, at least 0.5 µm, at least 1 µm, at least 2 µm, at least 3 µm, at least 4 µm, at least 5 µm, at least 10 µm, at least 15 µm, or at least 20 µm. In some embodiments, the continuous microfiber layer has an average flow orifice diameter of up to 0.5 µm, up to 1 µm, up to 2 µm, up to 3 µm, up to 4 µm, up to 5 µm, up to 10 µm, up to 15 µm, up to 20 µm, up to 25 µm, up to 30 µm, or up to 35 µm. In an exemplary embodiment, the continuous microfiber layer has an average flow orifice diameter in the range of 10 µm to 25 µm. In another exemplary embodiment, the continuous microfiber layer has an average flow orifice diameter in the range of 1 µm to 3 µm. In some embodiments, the average flow orifice diameter is preferably an average flow orifice diameter determined using capillary flow porosity measurement, as illustrated in the examples.

[0360] In some embodiments, the average flow pore size of the continuous fiber layer and the support layer is at least 0.1 µm, at least 0.5 µm, at least 1 µm, at least 2 µm, at least 3 µm, at least 4 µm, at least 5 µm, at least 10 µm, at least 15 µm, or at least 20 µm. In some embodiments, the average flow pore size of the continuous fiber layer and the support layer is up to 0.5 µm, up to 1 µm, up to 2 µm, up to 3 µm, up to 4 µm, up to 5 µm, up to 10 µm, up to 15 µm, up to 20 µm, up to 25 µm, up to 30 µm, or up to 35 µm. In an exemplary embodiment, the average flow pore size of the continuous fiber layer and the support layer is in the range of 1 µm to 3 µm.

[0361] In some embodiments, the continuous fine fiber layer has a narrow pore size distribution.

[0362] In some embodiments, the pore size distribution can be quantified using the ratio of P95 to P50. "P50" is the average flow pore size calculated as described in the methods of Examples 10 to 14. "P95" is the pore size when 95% of the flow through the layer passes through pores having an effective diameter of that size or smaller, calculated as described in the methods of Examples 10 to 14. Therefore, the ratio of P95 to P50 of the layer (P95 / P50) is a measure of the breadth of the medium pore size distribution of the layer. In some embodiments, for example, a continuous fine fiber layer may have a P95 / P50 ratio of up to 1.2, up to 1.4, up to 1.6, up to 1.8, up to 2, up to 2.5, up to 3, or up to 4.

[0363] In some embodiments, the continuous fine fiber layer has a density of at least 0.005 g / m². 2 At least 0.01 g / m 2 At least 0.05g / m 2 At least 0.1 g / m 2 At least 0.5 g / m 2 At least 1 g / m 2 At least 1.5 g / m 2 At least 2 g / m 2 Or at least 2.5 g / m 2 The basis weight. In some embodiments, the continuous fiber layer has a basis weight of up to 1.5 g / m. 2 Up to 2 g / m 2 Up to 2.5 g / m 2 Up to 3 g / m 2 Up to 3.5 g / m 2 Up to 4 g / m 2 Up to 4.5 g / m 2 Up to 5 g / m 2 Up to 10 g / m 2 Up to 15 g / m 2 Up to 20 g / m 2 Up to 25 g / m 2 Up to 50 g / m 2 The basis weight. In an exemplary embodiment, the continuous fine fiber layer has a basis weight of at least 0.1 g / m. 2 And up to 20 g / m 2 The basis weight. In another exemplary embodiment, the continuous fine fiber layer has a basis weight of at least 0.1 g / m. 2 And up to 1 g / m 2 The basis weight. In a further exemplary embodiment, the continuous fine fiber layer has a basis weight of 0.43 g / m. 2 The basis weight. When fibers of different diameters are layered, the basis weight of the continuous fine fiber layer will be cumulative.

[0364] In some embodiments, the thickness of the continuous microfiber layer is the average diameter of at least the largest microfiber in the continuous microfiber layer. In some embodiments, the continuous microfiber layer has a thickness of at least 200 nm, at least 300 nm, at least 400 nm, at least 500 nm, at least 600 nm, at least 700 nm, at least 800 nm, at least 900 nm, or at least 1000 nm. In some embodiments, the continuous microfiber layer has a thickness of up to 600 nm, up to 1000 nm, up to 5000 nm (5 µm), or up to 10 µm.

[0365] Properties of continuous fine fibers

[0366] The fine fibers disclosed herein comprise fiber-forming polymer materials. In some embodiments, the fine fibers disclosed herein can be made by spinning the fiber-forming polymer material alone. In some embodiments, the fine fibers disclosed herein can be made by spinning a combination of the fiber-forming polymer material and another substance.

[0367] The following disclose microfiber techniques for polymer materials that can be mixed or blended with a variety of other substances: Chung et al., U.S. Patent No. 6,743,273; Chung et al., U.S. Patent No. 6,924,028; Chung et al., U.S. Patent No. 6,955,775; Chung et al., U.S. Patent No. 7,070,640; Chung et al., U.S. Patent No. 7,090,715; Chung et al., U.S. Patent Publication No. 2003 / 0106294; Barris et al., U.S. Patent No. 6,800,117; and Gillingham et al., U.S. Patent No. 6,673,136. Additionally, in Ferrer et al., U.S. Patent No. 7,641,055, a high-strength polymer material insoluble in water is produced by mixing or blending a polysulfone polymer with a polyvinylpyrrolidone polymer, thereby generating a single-phase polymer alloy for electrospinning microfiber materials.

[0368] Continuous fine fibers can comprise fibers made from any suitable polymer. In some embodiments, polyamides can be used as the polymeric material for continuous fine fibers. One class of useful polyamide condensates is nylon material. The term "nylon" is a generic name for all long-chain synthetic polyamides. Typically, nylon nomenclature includes a series of numbers, such as nylon-6,6, which indicates that the starting material is a C6 diamine and a C6 dicarboxylic acid (the first number indicates the C6 diamine, and the second number indicates the C6 dicarboxylic acid compound). Another type of nylon can be produced by polycondensation of ε-caprolactam in the presence of a small amount of water. This reaction forms nylon-6 as a linear polyamide (made from a cyclic lactam also known as ε-aminocaproic acid). Furthermore, nylon copolymers are also considered. Exemplary nylon materials include nylon-6, nylon-6,6, nylon-6,10, mixtures thereof, or copolymers thereof.

[0369] Copolymers can be manufactured by combining various diamine compounds, various diacid compounds, and various cyclic lactam structures in a reaction mixture, and then forming a nylon with a polyamide structure using randomly positioned monomer materials. For example, nylon-6, 6-6, 10 materials are nylons manufactured from hexamethylenediamine and blends of C6 and C10 diacids. Nylon-6-6, 6-6, 10 is produced by blending ε-aminohexanoic acid, hexamethylenediamine, and C6 diacid materials with C10 diacids. 10Nylon is manufactured by copolymerizing blends of diacid materials. In this document, the term "polymer" includes polymers made from two or more different monomers, and includes trimers, etc.

[0370] In some embodiments, the microfibers of the continuous microfiber layer may preferably comprise nylon. In some embodiments, the microfibers may comprise a nylon copolymer resin. In an exemplary embodiment, the microfibers comprise SVP 651 (Shakespeare Co., Columbia, South Carolina), a terpolymer with a number average molecular weight of 21,500-24,800, comprising 45% nylon-6, 20% nylon-6,6 and 25% nylon-6,10. Not wishing to be bound by theory, it is believed that the nylon in the microfibers of the continuous microfiber layer will not undergo significant swelling during use of the filter media (including, for example, in a face mask). Significant swelling would result in an observed increase in media pressure drop (and, in the case of a face mask, an increase in difficulty breathing through the filter media).

[0371] In some embodiments, one or more polymeric materials of fine fibers are selected to resist significant swelling during use of the filter media, including, for example, during use of the filter media in a face mask. Although those skilled in the art will understand that polymers may swell if immersed in liquid, for some polymers, less or no swelling can be expected even in a moisture-filled atmosphere, including, for example, the atmosphere formed in a face mask filter during use.

[0372] In some embodiments, the fibers of the continuous microfiber layer may not be cross-linked (including, for example, by a cross-linking agent such as melamine-formaldehyde resin). Without being bound by theory, it is believed that cross-linking of the continuous microfiber layer can lead to an increase in the density of the continuous microfiber layer due to the more compact packing of the fibers. This increased density results in an observed increase in media pressure drop (and, in the case of a mask, an increase in difficulty breathing through the filter media).

[0373] In some embodiments, polysulfone can be used as a polymer material for continuous fine fibers. Exemplary polysulfones include polysulfone (PS), polyethersulfone (PES), and polyphenylene sulfone (PPSF) and mixtures thereof.

[0374] In some embodiments, polymeric materials comprising cellulose derivatives can be used as polymeric materials for continuous fine fibers. Examples of such polymers include ethyl cellulose, hydroxyethyl cellulose, cellulose acetate (including cellulose diacetate (DAC) and cellulose triacetate (TAC)), cellulose acetate butyrate, cellulose acetate propionate, cellulose acetate phthalate, and mixtures thereof.

[0375] In some embodiments, the polymeric material of the continuous fine fibers may additionally or alternatively include polypropylene (PP), polyvinylpyrrolidone (PVP), poly(4-vinylpyridine) (P4VP), polyvinylidene fluoride (PVDF), or polytetrafluoroethylene (PTFE, also known as Teflon), or mixtures thereof.

[0376] In some embodiments, the polymer crosslinked with resinous aldehydes can be used as a polymer material for continuous fine fibers, as described, for example, in International Publication No. WO 2013 / 043987 A1.

[0377] In some embodiments, the continuous microfiber layer has a thickness of up to 50 µm, up to 20 µm, up to 12 µm, or up to 10 µm. In some embodiments, a thinner continuous microfiber layer may be preferred. In some embodiments, the continuous microfiber layer has a thickness of at least 0.5 µm, at least 1 µm, at least 3 µm, at least 5 µm, or at least 8 µm. For example, in an exemplary embodiment, the continuous microfiber layer has a thickness of 8 µm to 12 µm. In another exemplary embodiment, the continuous microfiber layer has a thickness in the range of 0.5 µm to 12 µm. In yet another exemplary embodiment, the continuous microfiber layer has a thickness in the range of 0.5 µm to 10 µm.

[0378] In some embodiments, the thickness of the continuous microfiber layer is the thickness of at least several (e.g., two, three, four or more) fibers having the average diameter of the largest microfiber in the continuous microfiber layer. For example, the continuous microfiber layer may have a thickness of at least 2 µm, at least 3 µm, at least 4 µm or at least 5 µm.

[0379] In some embodiments, the solidity of the continuous microfiber layer is greater than that of one or more other layers in the filter medium, including, for example, a support layer or an efficiency layer, or both. While not wishing to be bound by theory, although layers with high solidity typically result in increased pressure drop, it is believed that providing a very thin continuous microfiber layer can contribute to improved efficiency without the corresponding pressure drop typically observed.

[0380] In some embodiments, the continuous fine fiber layer has an average flow orifice diameter similar to that of the efficiency layer. In some embodiments, the continuous fine fiber layer has a narrower pore size distribution than that of the efficiency layer.

[0381] In some embodiments, as further described below, the microfibers can be manufactured by combining a fiber-forming polymer material with at least one material that reacts with and / or crosslinks the fiber-forming polymer material. While not wishing to be bound by theory, it may be advantageous to avoid including materials that react with and / or crosslink with the fiber-forming polymer material, as such polymers can produce more stacked or open morphologies, thereby increasing the overall air permeability of the resulting microfiber layer and filter media.

[0382] In some embodiments, the fine fibers disclosed herein can be manufactured by combining a fiber-forming polymer material and at least two reactive additives capable of reacting with each other, for example, during fiber formation or in a post-processing step, as further described in International Patent Publication No. WO 2014 / 164130. The at least two reactive additives may optionally react with the fiber-forming polymer.

[0383] In some embodiments, the fine fibers disclosed herein can be manufactured by combining fiber-forming polymer materials and resinous aldehyde compositions such as melamine-formaldehyde resin.

[0384] In some embodiments, the resinous aldehyde composition comprises a "polymer-reactive resinous aldehyde composition." The "polymer-reactive resinous aldehyde composition" comprises alkoxy groups, as further described in U.S. Patent No. 9,587,328. In the final fiber, at least a portion of the polymer-reactive resinous aldehyde composition will participate in the crosslinking of the polymer and optionally may participate in self-crosslinking. The fiber-forming polymer material also includes reactive groups. Herein, "reactive" means that the polymer contains one or more functional groups (e.g., active hydrogen groups) capable of crosslinking through the alkoxy groups of the polymer-reactive resinous aldehyde composition used to manufacture the fine fibers.

[0385] In some embodiments, the resinous aldehyde composition comprises a "polymer-nonreactive resinous aldehyde composition". The polymer-nonreactive resinous aldehyde composition includes reactive groups for self-crosslinking, as further described in U.S. Patent No. 9,435,056. In the final fiber, at least a portion of the polymer-nonreactive resinous aldehyde composition will participate in self-crosslinking.

[0386] As used herein, “resin” or “resinate” refers to monomers, oligomers, and / or polymers, particularly monomers, oligomers, and / or polymers having the property of migrating to the surface of the fine fibers during fiber formation. In this document, the term “resinate aldehyde composition” refers to both the starting material and the material in the final fiber.

[0387] These components can be combined in solution or melt form. In some embodiments, the fine fibers are electrospun from a solution or dispersion. Thus, the polymeric material and resinous aldehyde (e.g., melamine-aldehyde) composition can be dispersed or dissolved in at least one common solvent or solvent blend suitable for electrospinning.

[0388] In some embodiments, beaded fibers, such as those shown in Example 13, may be preferably used. Without being bound by theory, it is believed that beaded fibers can reduce the solidity of the fiber structure. (See also Zhao et al., DOI:10.5772 / intechopen.74661 (2018).)

[0389] Methods for forming continuous fine fiber layers

[0390] In another aspect, this disclosure describes a method for manufacturing a continuous layer of fine fibers.

[0391] Continuous layers of fine fibers can be formed by any suitable method. For example, the fine fibers disclosed herein can be made using a variety of techniques, including electrospinning, force spinning, wet spinning, dry spinning, melt spinning, extrusion spinning, direct spinning, gel spinning, and the use of the island-island method.

[0392] In some embodiments, the components of the continuous fine fiber layer may be combined in solution or melt form. In some embodiments, the fine fibers are electrospun from a solution or dispersion. For example, the polymer material and resinous aldehyde composition may be dispersed or dissolved in at least one common solvent or solvent blend suitable for electrospinning.

[0393] In some embodiments, a continuous fiber layer may be formed on a support layer. In some embodiments, a continuous fiber layer may be formed on an efficiency layer.

[0394] In some embodiments, where fibers of different diameters can form different layers in a continuous layer of fine fibers, larger fibers can be deposited on the support before smaller fibers are deposited. Depending on the number of layers, additionally or alternatively, smaller fibers can be deposited on the support before larger fibers are deposited.

[0395] In some embodiments, fibers of different diameters can be formed simultaneously when they can form the same layer in a continuous layer of fine fibers.

[0396] The fine fibers are collected on the support layer during formation, for example, electrostatic or melt spinning, and are typically heat-treated after fiber manufacturing. Preferably, a continuous layer of fine fibers is disposed on the first surface of a permeable coarse fiber medium layer (i.e., the support layer) that serves as the fiber layer.

[0397] Considering the desired size and other properties for a continuous layer of fine fibers, those skilled in the art can select suitable polymers and polymer concentrations. For example, in some embodiments, the fibers will preferably be compatible with the fluid they are used to filter (e.g., hydraulic fluid, fuel, lubricant). Fibers are considered compatible with the fluid if they do not react with the fluid or any other components and additives therein and are insoluble in the fluid (so that the fine fiber structure is not chemically or physically damaged when in contact with the fluid only). In an exemplary embodiment, the polymer solution includes solution 1, as described in the example. In an exemplary embodiment, the polymer solution includes solution 2, as described in the example.

[0398] In some embodiments, fibers of different diameters can be formed simultaneously when they are mixed. For example, when forming two (or more) fibers by electrospinning, fibers can be formed by simultaneous co-spinning, including, for example, by using two (or more) syringes, each containing a different polymer solution. Alternatively or alternatively, each syringe can use a different syringe pump feed rate. In some embodiments, when mixing fibers of different diameters, fibers can be formed by alternating but very short pulses of each polymer solution (e.g., a maximum of 10 seconds, a maximum of 20 seconds, or a maximum of 30 seconds).

[0399] In some embodiments, when fibers of different diameters are layered, these fibers can be formed by alternating fiber formation. For example, when forming two (or more) fibers by electrospinning, fibers can be formed by alternately spinning each fiber, including, for example, by using two (or more) syringes, each containing a different polymer solution. Alternatively or alternatively, each syringe can use a different syringe pump feed rate. In some embodiments, when fibers of different diameters are layered, fibers can be formed by alternating pulses of each polymer solution for at least 30 seconds.

[0400] Any suitable method that can be used to form a combination of small and large fiber layers can be used. Exemplary methods that can be used to form layered fiber structures include one or more of the methods in group A5, group B, group D5, group E, group I5, or group J of Table 5. Exemplary methods that can be used to form hybrid fiber structures include one or more of the methods in group A6, group D, group D6, group I, or group L of Table 5. In some embodiments, a layer combination comprising both layered fiber structures and hybrid fiber structures can be formed. Exemplary methods for forming such structures are described in the examples.

[0401] Efficiency layer

[0402] The efficiency layer (if included) is a wet-laid nonwoven filter medium.

[0403] In some embodiments, the efficiency layer comprises bicomponent fibers and efficiency fibers, wherein the diameter of the efficiency fibers is smaller than that of the bicomponent fibers. In some embodiments, the efficiency layer may further comprise microfibrillated cellulose.

[0404] In some embodiments, the efficiency layer acts as a deep load layer.

[0405] In some embodiments, the efficiency layer is preferably a wet-laid web forming medium.

[0406] In some embodiments, the solidity of the efficiency layer is less than that of the continuous fine fiber layer.

[0407] In some embodiments, the efficiency layer has a reality of at least 3%, at least 4%, at least 5%, at least 6%, at least 7%, at least 8%, at least 9%, or at least 10%. In some embodiments, the efficiency layer has a reality of up to 8%, up to 9%, up to 10%, up to 11%, up to 12%, up to 13%, up to 14%, or up to 15%. In an exemplary embodiment, the efficiency layer has a reality in the range of 7% to 12%. In some embodiments, the reality of the efficiency layer is preferably calculated as described in the methods of Examples 10 to 14.

[0408] In some embodiments, the efficiency layer has a thickness of at least 0.05 mm, at least 0.1 mm, at least 0.2 mm, or at least 0.3 mm. In some embodiments, the efficiency layer has a thickness of up to 0.5 mm, up to 1 mm, up to 5 mm, up to 10 mm, up to 25 mm, or up to 50 mm. In some embodiments, the efficiency layer has a thickness in the range of 0.2 mm to 50 mm. In some embodiments, the efficiency layer has a thickness in the range of 0.2 mm to 1 mm. In some embodiments, the efficiency layer has a thickness in the range of 0.2 mm to 0.5 mm.

[0409] As described above, in some embodiments, the continuous microfiber layer has an average flow aperture similar to that of the efficiency layer. It is undesirable to be bound by theory; it is believed that if the average flow aperture of the continuous microfiber layer is much smaller than that of the efficiency layer, a larger proportion of particles will be captured by the continuous microfiber layer, thereby reducing filter life. On the other hand, if the average flow aperture of the continuous microfiber layer is much larger than that of the efficiency layer, the efficiency layer must have high density, and the filter will again suffer a reduced life due to lower capacity.

[0410] It will be recognized that the average flow orifice size can be selected based on the desired efficiency of the filter media and the size of the particles being filtered.

[0411] In exemplary embodiments, the efficiency layer has an average flow orifice diameter of at least 1 µm, at least 5 µm, at least 10 µm, at least 15 µm, or at least 20 µm. In exemplary embodiments, the efficiency layer has an average flow orifice diameter of up to 5 µm, up to 10 µm, up to 15 µm, up to 20 µm, up to 25 µm, up to 30 µm, or up to 35 µm. In certain exemplary embodiments, the efficiency layer fibers have an average flow orifice diameter range of 10 µm to 25 µm. In some embodiments, the average flow orifice diameter is preferably an average flow orifice diameter determined using capillary flow porosity measurement, as described in the methods of Examples 10 to 14.

[0412] In some embodiments, the efficiency layer has a wider pore size distribution than the adjacent continuous fiber layers. In some embodiments, the pore size distribution can be quantified using a P95 to P50 ratio. In some embodiments, for example, the efficiency layer may have a P95 / P50 ratio of up to 2, up to 2.5, up to 3, up to 4, up to 5, up to 10, or up to 20.

[0413] In some embodiments, the average flow orifice diameter of the efficiency layer is preferably similar to that of the continuous microfiber layer. For example, if the continuous microfiber layer has an average flow orifice diameter range of 10 µm to 25 µm, then the efficiency layer also has an average flow orifice diameter range of 10 µm to 25 µm. In another exemplary embodiment, if the continuous microfiber layer has an average flow orifice diameter range of 15 µm to 20 µm, then the efficiency layer also has an average flow orifice diameter range of 15 µm to 20 µm.

[0414] In some embodiments, the average flow orifice diameter (P50) of the fine fiber layer can be within 1%, 2%, 3%, 5%, 10%, 20%, 30%, 50%, 100%, or 200% of the average flow orifice diameter (P50) of the adjacent efficiency layer.

[0415] As described above, in some embodiments, the continuous fiber layer has a narrower pore size distribution than the adjacent efficiency layer.

[0416] For example, in some embodiments, the P95 / P50 ratio of the efficiency layer adjacent to the fiber layer can be up to 1.5 times, up to 2 times, up to 3 times, up to 4 times, up to 5 times, up to 6 times, up to 7 times, up to 8 times, up to 9 times, or up to 10 times greater than the P95 / P50 ratio of the fiber layer.

[0417] In some embodiments, the resinous binder component is not necessary to achieve sufficient strength for the efficiency layer. In some embodiments, the resinous binder component is not included in the efficiency layer.

[0418] In some embodiments, the efficiency layer includes Synteq XP™ synthetic liquid media (Donaldson Company, Inc) with a 10-micron efficiency rating or Synteq XP™ synthetic liquid media (Donaldson Company, Inc) with a 5-micron efficiency rating.

[0419] bicomponent fibers

[0420] The efficiency layer comprises bicomponent fibers. Any suitable bicomponent fibers may be used, and the bicomponent fibers include any bicomponent fibers (or combinations thereof) described in the bicomponent fiber section of Part A of this disclosure.

[0421] High-efficiency fine fibers

[0422] Efficient fibers can be made from any suitable material. For example, efficient fibers may include glass, metal, silica, polymer fibers, or other related fibers, or mixtures thereof. Efficient fibers are typically monocomponent fibers with a diameter ranging from 0.1 µm to 50 µm, or more preferably from 0.1 µm to 10 µm.

[0423] In some embodiments, the efficiency fiber includes glass fiber.

[0424] In some embodiments, the efficiency fiber comprises short-cut fine fibers of materials other than glass. In some embodiments, the efficiency fiber preferably does not include glass fibers.

[0425] Short-cut fine fibers can include, for example, hydrophilic, hydrophobic, oleophilic, or oleophobic fibers.

[0426] Short-cut fine fibers can include one or more of a variety of materials, including naturally occurring cotton, flax, wool, various cellulose and protein natural fibers, or synthetic fibers (including, for example, rayon, acrylic fibers, aramid fibers, nylon, polyolefins, and polyester fibers).

[0427] Microfiber

[0428] The first and second filter media each comprise microfibrils. Any suitable microfibrils may be used, and the microfibrils may be any of those described in the microfibrils section of Part A of this disclosure.

[0429] support layer

[0430] An optional support layer for the filter media (also referred to herein as a “substrate” or “sparse cloth”) may comprise any material suitable for providing support for the continuous microfiber layer during its manufacture, use, or both. When the filter media does not include a support layer, the continuous microfiber layer may be formed directly on the efficiency layer.

[0431] In some embodiments, the support layer includes any of the support layers or features of the support layer described in the support layer section of Part B of this disclosure.

[0432] Alternatively or additionally, the support layer may include any of the features described below.

[0433] The support layer may include or be made of any suitable porous material.

[0434] Typically, fibrous materials are used for the support layer. The fibers of the support layer can be made of natural fibers and / or synthetic fibers. Suitable fibers may include cellulose fibers, glass fibers, metal fibers, or synthetic polymer fibers, or combinations or mixtures thereof.

[0435] In some embodiments, the support layer comprises fibers having an average diameter of at least 5 micrometers or at least 10 micrometers. In some embodiments, the support layer comprises fibers with an average diameter of up to 250 micrometers.

[0436] In some embodiments, the thickness of the support layer is at least 0.005 inches (125 micrometers), and typically at least 0.01 inches (250 micrometers). In some embodiments, the thickness of the support layer is up to 0.03 inches (750 micrometers).

[0437] In some embodiments, the support layer has a strength of at least 8 g / m². 2 At least 10 g / m 2 At least 15 g / m 2 or at least 20g / m 2 The base weight. In some embodiments, the support layer has a maximum weight of 70 g / m². 2 Up to 100 g / m 2 or up to 150g / m 2 The base weight. In an exemplary embodiment, the support layer has a base weight of 8 g / m. 2 Up to 150 g / m 2 The base weight is within the range. In another exemplary embodiment, the support layer has a base weight of 15 g / m³. 2 Up to 100 g / m 2 Basis weight within the range.

[0438] In some embodiments, the support layer has a solidity of at least 5%, at least 10%, at least 20%, at least 25%, at least 30%, or at least 40%. In some embodiments, the support layer has a solidity of up to 10%, up to 20%, up to 25%, up to 30%, up to 40%, or up to 50%. In an exemplary embodiment, the support layer has a solidity in the range of 10% to 40%. In another exemplary embodiment, the support layer has a solidity in the range of 20% to 30%.

[0439] In some embodiments, the support layer has an average flow orifice diameter of at least 5 µm, at least 10 µm, at least 15 µm, at least 20 µm, at least 25 µm, at least 30 µm, at least 35 µm, at least 40 µm, or at least 45 µm. In some embodiments, the support layer has an average flow orifice diameter of up to 10 µm, up to 15 µm, up to 20 µm, up to 25 µm, up to 30 µm, up to 35 µm, up to 40 µm, up to 50 µm, up to 60 µm, up to 70 µm, up to 80 µm, up to 90 µm, or up to 100 µm. In an exemplary embodiment, the support layer has an average flow orifice diameter in the range of 10 µm to 25 µm. In another exemplary embodiment, the support layer has an average flow orifice diameter in the range of 40 µm to 60 µm. In some embodiments, the average flow orifice diameter is preferably an average flow orifice diameter determined using capillary flow porosity measurement, as illustrated in the examples.

[0440] In some embodiments, the support layer has a maximum pore size of up to 10 µm, up to 15 µm, up to 20 µm, up to 25 µm, up to 30 µm, up to 35 µm, up to 40 µm, up to 50 µm, up to 60 µm, up to 70 µm, up to 80 µm, up to 90 µm, up to 100 µm, or up to 150 µm. In an exemplary embodiment, the support layer has a maximum pore size of up to 90 µm. In another exemplary embodiment, the support layer has a maximum pore size of up to 70 µm.

[0441] In some embodiments, the maximum pore size of the support layer (e.g., nylon sparse fabric) can be determined according to one of the following methods.

[0442] In some embodiments, the maximum pore size is the average maximum pore size determined using capillary flow porosity measurement, as illustrated in the examples.

[0443] Alternatively, in some embodiments, a 10-inch by 10-inch sparse cloth is divided into nine equal parts, and three samples are taken from each part. The maximum pore size is taken as the average of three maximum measurements from twenty-seven different tests.

[0444] In an alternative approach, the maximum pore size is determined by imaging the fibers using SEM and measuring the area between the fibers in the resulting micrographs. Image processing software, such as ImageJ and / or (FIJI Is Just ImageJ (FIJI), or newer versions of ImageJ), can then be used for pore size determination.

[0445] In some embodiments, the support layer has a minimum pore size of at least 5 µm, at least 10 µm, at least 15 µm, at least 20 µm, at least 25 µm, at least 30 µm, at least 35 µm, at least 40 µm, or at least 50 µm. In an exemplary embodiment, the support layer has a minimum pore size of at least 20 µm.

[0446] In some embodiments, the minimum pore size is preferably the average minimum pore size determined using capillary flow porosity measurement, as illustrated in the examples.

[0447] In some embodiments, the support layer preferably comprises a consistent media structure, meaning that the characteristics of the media (including, for example, the pore size, solidity, basis weight, or thickness of the media, or combinations of these characteristics, or each of these characteristics) are consistent across the entire length and width of the media. For example, in an exemplary embodiment, the average flow pore size varies by no more than 30%, more preferably no more than 25%, and even more preferably no more than 15% across the length and width of the media.

[0448] Unwilling to be constrained by theory, it is believed that the interaction between the fiber diameter of the continuous microfiber layer, the thickness of one or more continuous microfiber layers, and the maximum pore size of the support layer is crucial for achieving structurally robust and efficient media. For example, using only high basis weights (e.g., greater than 60 g / m³) 2The support layer does not produce a structurally robust medium because if the maximum pore size of the support layer exceeds a certain size (e.g., 90 µm), if the fiber diameter is below a certain size, and / or if the fiber thickness is small, the continuous fiber layer will be structurally compromised during filtration at sufficiently high pressure drops. For example, when smaller fibers (e.g., average diameter up to 500 nm) are used for the continuous fiber layer on a support layer with a maximum pore size of 88 µm, it has been found that increasing the basis weight of the continuous fiber layer requires unsustainable high pressures to allow fluid to pass through the medium; in contrast, decreasing the basis weight of the continuous fiber layer causes the layer to become structurally compromised during filtration. Although increasing the fiber size (e.g., average diameter at least 600 nm, more preferably at least 900 nm) of at least one fiber deposited in the continuous fiber layer on the support layer with a maximum pore size of 88 µm reduces the efficiency of the medium, increasing the fiber size also reduces the pressure drop and produces a structurally robust medium that does not become structurally compromised during use.

[0449] The support layer can be formed of any suitable material. Examples of suitable materials for the support layer include spunbond, wet-laid, carded, or meltblown nonwoven materials or combinations thereof, including, for example, spunbond-meltblown-spunbond materials. The fibers can be in the form of a woven or nonwoven fabric. Examples of synthetic nonwovens include polyester nonwovens, nylon nonwovens, polyolefin (e.g., polypropylene) nonwovens, polycarbonate nonwovens, or blends or multicomponent nonwovens thereof. Sheet-like support layers (e.g., cellulose webs, synthetic webs, and / or glass webs or composite webs) are typical examples of filter support layers. Other examples of suitable support layers include polyester or bicomponent polyester fibers or polypropylene / polyethylene terephthalate, or polyethylene / polyethylene terephthalate bicomponent fibers in spunbond fabrics.

[0450] In some embodiments, the support layer may preferably comprise polymer fibers. One or more polymers may be selected for the polymer fibers to adhere to the polymer of the continuous microfiber layer. In some embodiments, the polymer fibers may comprise nylon fibers or polyester fibers. For example, if the continuous microfiber layer comprises nylon microfibers, the support layer may preferably comprise nylon.

[0451] In some embodiments, the support layer may preferably comprise spunbond fibers.

[0452] In some embodiments, the support layer is a thin medium (e.g., less than 0.5 mm) that exhibits high transmittance, high tensile strength, and small, uniform pore size.

[0453] In an exemplary embodiment, the support layer comprises CEREX 23200 (Cerex Advanced Fabrics, Inc., Candenman, Florida). CEREX 23200 comprises nylon 6,6 with a thickness of 8.4 mils (0.21 mm) and a density of 67.8 g / m². 2 Basis weight, 28% solidity, and transmittance / solidity of 615.1.

[0454] As illustrated in the example, using capillary flow porosity measurement, the average maximum pore size of the CEREX 23200 was found to be 66.4 µm ± 21.9 µm, the average flow pore size was 51.4 µm ± 12.1 µm, and the average minimum pore size was 29.1 µm ± 9.7 µm.

[0455] Characteristics and Application Methods of Nonwoven Filter Media and Composite Materials

[0456] The filter media or composite materials described herein can be used in any method conceived by those skilled in the art.

[0457] In some embodiments, the filter media or composite materials described herein may be incorporated into the filter element.

[0458] In some embodiments, one or more filter media or composite materials comprising portions A through F above are suitable for incorporation into medical face masks or face mask systems, as further described below.

[0459] In some embodiments, the filter media exhibits strength and durability when folded, stitched, and / or thermally welded during processing, while still achieving the desired filtration performance.

[0460] In some embodiments, the nonwoven filter media or composite materials conform to the National Institute for Occupational Safety and Health (NIOSH) standards, such as NIOSH P95, NIOSH P99, NIOSH P100, NIOSH N95, NIOSH N99 and / or NIOSH 95 classifications, as compiled in 42 CFR § 84.

[0461] In some embodiments, the nonwoven filter media or composite material exhibits a submicron-specific efficiency for Class 1, Class 2 and / or Class 3 barriers as defined by ASTM F2100-19 (the efficiency of the filter media in capturing atomized particles smaller than one micrometer, expressed as the percentage of a known number of particles that do not pass through the medical mask material at a given flow rate).

[0462] In an exemplary embodiment, for particles of 0.3 micrometers, the nonwoven filter media or composite material exhibits an efficiency of at least 80%, at least 85%, at least 90%, at least 95%, at least 97%, at least 98%, or at least 99% at a flow rate of 10 feet per minute (FPM). In an exemplary embodiment, the nonwoven filter media preferably exhibits an efficiency of at least 95%. In another exemplary embodiment, the nonwoven filter media or composite material preferably exhibits an efficiency of at least 99%.

[0463] In an exemplary embodiment, the filter media or composite material exhibits an efficiency of at least 80%, at least 85%, at least 90%, at least 95%, at least 97%, at least 98%, or at least 99% for 0.3 micrometer particles at a flow rate of 10 feet per minute (FPM). In an exemplary embodiment, the filter media or composite material preferably exhibits an efficiency of at least 95%. In another exemplary embodiment, the filter media or composite material preferably exhibits an efficiency of at least 98%.

[0464] In some embodiments, the nonwoven filter media or composite material exhibits high air permeability or airflow. Efficiency can be increased to the point where permeability or airflow is reduced to maintain the wearer's ability to breathe freely.

[0465] In some embodiments, the nonwoven filter media or composite material exhibits at least 1 ft of air permeability at 0.5 inches underwater, as measured by ASTM D737-18 entitled "Test Method for Air Permeability of Textile Fabrics". 3 / ft 2 / min, at least 2 ft underwater at 0.5 inches. 3 / ft 2 / min, at least 5 ft underwater at 0.5 inches. 3 / ft 2 / min, at least 10 ft underwater at 0.5 inches. 3 / ft 2 / min, at least 15 ft underwater at 0.5 inches. 3 / ft 2 / min or at least 20 ft underwater at 0.5 inches. 3 / ft 2 / min air transmittance (also known as Fraser air transmittance or airflow). In some embodiments, the nonwoven filter media exhibits up to 30 ft at 0.5 inches of water, as measured according to ASTM D737-18. 3 / ft 2 / min, up to 50 ft at a depth of 0.5 inches. 3 / ft 2 / min, or up to 100 ft at a depth of 0.5 inches underwater. 3 / ft 2 / min air permeability. In an exemplary embodiment, the nonwoven filter media or composite material exhibits an air permeability of 1 ft at 0.5 inches of water. 3 / ft 2 / min to 100 ft at 0.5 inches underwater 3 / ft 2 Air permeability in the range of / min ft. In another exemplary embodiment, the nonwoven filter media or composite material exhibits air permeability in the range of 2 ft at 0.5 inches of water. 3 / ft 2 / min to 30 ft underwater at 0.5 inches 3 / ft 2 Air permeability within the range of / min.

[0466] In some embodiments, the fibrous medium exhibits at least 1 ft of air permeability at 0.5 inches underwater, as measured by ASTM D737-18 entitled "Test Method for Air Permeability of Textile Fabrics". 3 / ft 2 / min, at least 2 ft underwater at 0.5 inches. 3 / ft 2 / min, at least 5 ft underwater at 0.5 inches. 3 / ft 2 / min, at least 10 ft underwater at 0.5 inches. 3 / ft 2 / min, at least 15 ft underwater at 0.5 inches. 3 / ft 2 / min or at least 20 ft underwater at 0.5 inches. 3 / ft 2 / min air transmittance (also known as Fraser air transmittance or airflow). In some embodiments, the fiber medium exhibits up to 30 ft underwater at 0.5 inches, as measured according to ASTM D737-18. 3 / ft 2 / minute, up to 50 ft at a depth of 0.5 inches. 3 / ft 2 / min, or up to 100 ft at a depth of 0.5 inches underwater. 3 / ft 2 / min air transmittance. In an exemplary embodiment, the fiber medium exhibits an air transmittance of 1 ft at 0.5 inches of water. 3 / ft 2 / min to 100 ft at 0.5 inches underwater 3 / ft 2 Air permeability in the range of / min ft. In another exemplary embodiment, the fiber medium exhibits air permeability in the range of 2 ft at 0.5 inches of water. 3 / ft 2 / min to 30 ft underwater at 0.5 inches 3 / ft 2 Air permeability within the range of / min.

[0467] In some embodiments, the nonwoven filter media exhibits at least 10 g / m 2 At least 20 g / m 2 At least 25 g / m 2 At least 30 g / m 2 At least 35 g / m 2 At least 40 g / m 2 At least 50 g / m 2 At least 60 g / m 2 Or at least 70 g / m 2 The dry basis weight. In some embodiments, the nonwoven filter media exhibits up to 100 g / m³. 2 Up to 120 g / m 2 Up to 140 g / m 2 Up to 150 g / m 2 Up to 160 g / m 2 Up to 180 g / m 2 Up to 200 g / m 2 Up to 300g / m 2 or up to 400 g / m 2 The dry basis weight. In some embodiments, the nonwoven filter media disclosed herein has a dry basis weight of 25 g / m³. 2 Up to 300 g / m 2 The dry basis weight is within the range. In some embodiments, the nonwoven filter media disclosed herein has a dry basis weight of 35 g / m³. 2 Up to 150 g / m 2 The dry basis weight range. In an exemplary embodiment, the nonwoven filter media exhibits a dry basis weight of 40 g / m³. 2 Up to 200 g / m 2 The dry basis weight range. In another exemplary embodiment, the nonwoven filter media exhibits a dry basis weight of 60 g / m³. 2 Up to 120 g / m2 Dry basis weight within the range.

[0468] In some embodiments, the fiber medium exhibits at least 10 g / m 2 At least 20 g / m 2 At least 25 g / m 2 At least 30 g / m 2 At least 35 g / m 2 At least 40 g / m 2 At least 50 g / m 2 At least 60 g / m 2 Or at least 70 g / m 2 The dry basis weight. In some embodiments, the fiber media exhibits a maximum of 100 g / m³. 2 Up to 120 g / m 2 Up to 140 g / m 2 Up to 150 g / m 2 Up to 160 g / m 2 Up to 180 g / m 2 Up to 200 g / m 2 Up to 300 g / m 2 or up to 400g / m 2 The dry basis weight. In some embodiments, the fiber medium disclosed herein has a dry basis weight of 25 g / m³. 2 Up to 300 g / m 2 The dry basis weight is within the range. In some embodiments, the fiber medium disclosed herein has a dry basis weight of 35 g / m³. 2 Up to 150 g / m 2 The dry basis weight range. In an exemplary embodiment, the fibrous medium exhibits a dry basis weight of 40 g / m³. 2 Up to 200 g / m 2 The dry basis weight range. In another exemplary embodiment, the fibrous medium exhibits a dry basis weight of 60 g / m³. 2 Up to 120 g / m 2 Dry basis weight within the range.

[0469] In some embodiments, the nonwoven filter media exhibits a thickness of at least 100 micrometers, at least 150 micrometers, at least 0.2 mm, at least 0.25 mm, at least 0.3 mm, at least 0.35 mm, or at least 0.4 mm. In some embodiments, the nonwoven filter media exhibits a thickness of up to 1 mm, up to 1.1 mm, up to 1.2 mm, up to 1.3 mm, up to 1.4 mm, or up to 1.5 mm, up to 4 inches (10.2 cm), or up to 5 mm. In an exemplary embodiment, the nonwoven filter media exhibits a thickness in the range of 0.25 mm to 1.5 mm. In another exemplary embodiment, the nonwoven filter media exhibits a thickness in the range of 0.4 mm to 1.0 mm.

[0470] In some embodiments, the fiber medium exhibits a thickness of at least 100 micrometers, at least 150 micrometers, at least 0.2 mm, at least 0.25 mm, at least 0.3 mm, at least 0.35 mm, or at least 0.4 mm. In some embodiments, the fiber medium exhibits a thickness of up to 1 mm, up to 1.1 mm, up to 1.2 mm, up to 1.3 mm, up to 1.4 mm, or up to 1.5 mm, up to 4 inches (10.2 cm), or up to 5 mm. In an exemplary embodiment, the fiber medium exhibits a thickness in the range of 0.25 mm to 1.5 mm. In another exemplary embodiment, the fiber medium exhibits a thickness in the range of 0.4 mm to 1.0 mm.

[0471] In some embodiments, the stiffness of the nonwoven filter media or composite material can be quantified using the Gurley stiffness, which in some cases can be at least 2000 mg. However, in other cases, the Gurley stiffness can be less than 2000 mg. The Gurley stiffness can be calculated using a Gurley stiffness tester conforming to industry standards TAPPI #T543 OM-16 (2016) and ASTM D6125-97 (2007).

[0472] Face mask system

[0473] In some embodiments, the filter media or composite materials described herein may be incorporated into the filter element. In some embodiments, a combination of the filter media and composite materials described herein may be incorporated into the filter element.

[0474] In some embodiments, the filter element may preferably be incorporated into the mask system. In some embodiments, one or more filter media or composite materials comprising portions A through F above may be incorporated into the mask system.

[0475] Figures 3 to 4 An illustrative embodiment of a mask system in the form of a reusable respirator with a face mask 30 having a pair of filter elements attached thereto is depicted. The depicted mask system 20 includes a face mask 30 defining a face container 34 and filter elements 40 coupled to the face mask 30. The filter elements 40 are generally consistent with the filter elements described herein. The mask system 20 defines an intake airflow path 26 extending from the surrounding environment to the face container 34. The filter elements 40 are disposed across the intake airflow path 26.

[0476] The face container 34 is configured to receive a portion of the wearer's face. Specifically, the face container 34 is configured to receive the wearer's nose and mouth when the mask system 20 is positioned appropriately above the wearer's nose and mouth, for example... Figure 4 As depicted herein, the mask 30 can be made of a variety of different materials, such as flexible elastomers, foams, polymers, etc. In various embodiments, the mask 30 is made of a material that is substantially impermeable to airflow passing through it. The construction of the mask is well known and will not be described further herein.

[0477] refer to Figure 4 The depicted embodiment of the face mask system 20 includes a retaining feature configured to hold the face container 34 of the face mask system 20 on the wearer's face. The retaining feature includes a headband 22 configured to receive the wearer's head. The retaining feature also includes a strap 24 configured to extend around the wearer's head or neck.

[0478] The depicted embodiment of the face mask system 20 includes an exhalation valve 32 that defines an exhaust airflow path 28 from the face container 34 to the surrounding environment. The exhalation valve 32 is generally configured to allow exhaled air emitted by the wearer to flow out of the face container 34 defined by the face mask 30. In various embodiments, the exhalation valve 32 is configured as a one-way valve. Therefore, while the exhalation valve 32 allows exhaled air to leave the face container 34, it also prevents ambient air from entering the face container 34.

[0479] Air enters the face container 34 defined by the mask 30 through an opening formed in the mask 30. A filter element 40 is attached to the mask 30 above the opening formed in the mask 30. An intake airflow path 26 extends through the opening. The filter element 40 is positioned upstream of the face container 34 such that air entering the face container 34 from the ambient environment passes first through the filter element 40. In some embodiments, each filter element 40 is incorporated into a replaceable filter cartridge. Although the depicted embodiments include two filter elements 40, it should be understood that as few as one filter element 40 or three or more filter elements 40 may be used in one or more alternative embodiments of the reusable respirator described herein.

[0480] Furthermore, although the filter element 40 is depicted herein as being located on the outer surface of the mask 30, it should be understood that in one or more alternative embodiments, the filter element 40 may be contained within a housing or other protective structure. Such a housing or protective structure may be configured to prevent physical damage to the filter element 40 during use.

[0481] Figures 5 to 6 Another illustrative embodiment of a face shield system in the form of a surgical mask is depicted, which incorporates one or more filter elements 131 as described herein. Face shield system 120 includes a face shield 130 incorporating one or more filter elements 131 as described herein. Face shield 130 defines a face container 134 configured to receive a portion of a wearer's face. In this example, face container 134 is configured to extend above the wearer's nose and mouth. Face shield system 120 defines an airflow path 126 extending from the surrounding environment to face container 134, which is an intake airflow path. One or more filter elements 131 are disposed across airflow path 126. In this example, airflow path 126 is both an intake airflow path and an exhaust airflow path (extending from face container 134 to the surrounding environment).

[0482] The mask system 120 has a holding feature configured to hold the face container 134 in position on the wearer's face. The holding feature includes an upper strap 122 and a lower strap 124. In the current example, each of the upper strap 122 and the lower strap 124 is configured to be fastened together or otherwise attached behind the wearer's head. In some alternative embodiments, one or both of the upper strap 122 and the lower strap 124 may be a single elastic strap, for example, forming a loop with the mask 130 that is configured to extend around the wearer's head. In some alternative embodiments, each upper strap 122 corresponding to the lower strap 124 may be connected together to form a single elastic strap, for example, forming a loop with the mask 130 that is configured to extend around the wearer's ear. Other configurations are, of course, possible.

[0483] One or more filter elements 131 described herein may form at least a portion of a face mask 130. The filter element 131 may be positioned upstream of a face container 134 such that air entering the face container 134 from the surrounding environment first passes through the filter element 131. The filter element 131 of the face mask system 120 may define folds, such as an outer fold 136 and an inner fold 138 (see [link to documentation]). Figure 6The folds 136, 138 in filter element 131 can be configured to increase the surface area of ​​the filter medium available for filtration. The folds 136, 138 in filter element 131 can allow the mask 130 and thus the face container 134 to expand to accommodate the wearer's face. In the current example, mask 130 includes a rim 132 on the opposite side of mask 130. Although the depicted embodiments of surgical masks include a mask 130 defining folds, it should be understood that one or more alternative embodiments of masks incorporating one or more filter elements as described herein may or may not include folds. Furthermore, the number of folds and the placement of any such folds may also differ. The rim may be used to hold the folds formed in mask 130 of mask system 120.

[0484] In surgical masks, such as Figures 5 to 6 The mask system 120 depicted herein may incorporate the filter elements described herein into the mask 130 of the mask system 120. In one or more embodiments, the filter elements described herein may constitute substantially all of the mask 130 of the mask system 120.

[0485] Figures 7 to 8 Another illustrative embodiment of a mask system 220 in the form of a filtering mask respirator is depicted, comprising a molded cup-shaped mask 240 incorporating one or more filtering elements as described herein. The filtering elements are coupled to at least a portion of the mask 240 or define the shape of at least a portion of the mask. The mask 240 defines a face container 234 configured to receive a portion of the wearer's face, such as the wearer's nose and mouth. The mask system 220 defines an airflow path 228 extending from the surrounding environment to the face container 234, which may be referred to as an intake airflow path. The filtering elements are disposed across the airflow path 228. The filtering elements are positioned upstream of the face container such that air entering the face container 234 from the surrounding environment first passes through the filtering elements. In this example, the airflow path 228 also defines an exhaust airflow path extending from the face container 234 to the surrounding environment.

[0486] The depicted mask system 220 includes one or more retaining features 222 configured to hold the mask in place above the wearer's nose and mouth. Specifically, the retaining feature 222 may be an elastic strap configured to wrap around the wearer's head. In one or more embodiments, the face container 234 of the mask system 220 may include a deformable nose clip 226 configured to facilitate a seal of the mask over the wearer's nose.

[0487] The mask system 220 includes a mask 240 having a molded cup shape similar to that of a known filtering respirator. When the mask system 220 is in place above the wearer's nose and mouth, the mask 240 defines a face container 234 having a downstream air space that accommodates the wearer's nose and mouth. The downstream air space is configured downstream of the filtering element.

[0488] refer to Figure 8 The face mask 240 may be composed of one or more different layers / components 250, 252, and 254, at least one of which may be the filter element described herein. In one or more embodiments, one or more different layers / components may be provided to help the face mask 240 maintain its cup shape, wherein, for example, the filter element layer / component may not have sufficient rigidity to maintain that shape. Any such layer / component preferably does not significantly increase the flow resistance through the face mask 240. The different layers / components may be attached to each other by any suitable technique or combination of techniques, including but not limited to thermal bonding, chemical bonding, adhesives, stitching, welding, etc.

[0489] Figure 12 Another illustrative embodiment of a mask system in a powered air-purifying respirator 300 is depicted. The powered air-purifying respirator 300 has a mask 310 that is in fluid communication with the surrounding environment 350 via a filter element 330. The powered air-purifying respirator 300 defines an intake airflow path 316 from the surrounding environment 350 to a face container 314 defined by the mask 310. Specifically, the powered air-purifying respirator 300 defines an air inlet 322 in the surrounding environment and an air outlet 312 as an orifice defined by the mask 310. The filter element 330 is disposed across the intake airflow path 316. Thus, the intake airflow path 316 extends from the air inlet 322 through the filter element 330 to the mask body.

[0490] A face mask 310 defines a face container configured to receive a portion of the wearer's face. The face mask 310 is generally configured to isolate at least a portion of the wearer's face from the surrounding environment 350. Therefore, the face mask 310 is generally made of a substantially impermeable material. When the face mask 310 is in place above the wearer's nose and mouth, the face container 314 defines a relatively clean air space to accommodate the wearer's nose and mouth.

[0491] The face shield 310 typically has retaining features configured to maintain its position relative to the wearer. Specifically, in the present example, the face shield 310 is a helmet configured to receive the entire head of the wearer. The retaining feature may be a headband within the helmet configured to be secured to the wearer's head, or it may be an upper portion of the helmet configured to rest on and extend above the wearer's head. In some other embodiments, the face shield 310 may be configured to receive only a portion of the wearer's face, such as the user's nose and mouth. In still other embodiments, the face shield 310 is a component of clothing configured to receive the user's entire body. In some embodiments, the face shield 310 is configured to be at least partially optically transparent. The face shield 310 may be constructed from a variety of different materials and combinations thereof. In various embodiments, the face shield 310 is constructed from a substantially impermeable material. Various configurations are contemplated and are generally known in the art.

[0492] Similar to the above references Figures 3 to 4 As an example discussed, the mask may include an exhalation valve, which is a one-way valve defining a path for exhaust airflow from the face container to the surrounding environment. The exhalation valve may be configured to allow exhaled air emitted by the wearer to flow out through the face container 314. This exhalation valve will typically be configured to prevent ambient air from entering the face container 314.

[0493] Air enters from the outlet 312 of an airflow duct 318 through an opening leading to a face container 314 defined by a mask 310, the airflow duct defining at least a portion of an intake airflow path 316. An air generator 340 is configured to generate airflow along the intake airflow path 316 and through a filter element 330. In various embodiments, the air generator 304 may be a blower, such as a motorized blower. In some embodiments, the air generator 304 may be an air pump. A power source 342 may be operationally connected to the air generator 304. For example, the power source 342 may be a power source such as a battery pack.

[0494] The filter element 330 is typically in fluid communication with the face container 314. More specifically, the filter element 330 is typically upstream of the face container 314 along an intake airflow path 316. In this exemplary system, the filter element 330 is located away from the face mask 310, meaning that the filter element 330 is separated from the face mask 310 by a portion of the intake airflow path 316. In some embodiments, the filter element 330 and the air generator 340 are housed within a housing 320. The housing 320 may define a filter access point 324 through which a user can replace the filter element 330. Although in the current embodiment the air generator 340 is depicted downstream of the filter element 330, in some embodiments the air generator 340 may be upstream of the filter element 330. While a single filter element 330 is currently depicted, in some embodiments multiple filter elements may be combined in the face mask system.

[0495] Filter element

[0496] In some embodiments, the filter media disclosed herein may be included in a filter element. In some embodiments, the filter element may include a wire support member. The wire support member may be located downstream of a support layer.

[0497] The combinations of filter media and composite materials disclosed herein can also be included in filter elements. For example, in an exemplary embodiment, a filter media comprising microfibrillated fibers (Part A of this disclosure) can be combined with a filter media comprising continuous fine fibers (Part F of this disclosure). In another exemplary embodiment, a glass-free filter media (Part D of this disclosure) can be combined with a filter media comprising continuous fine fibers (Part F of this disclosure). In yet another exemplary embodiment, a glass-free composite material (Part E of this disclosure) can be combined with a filter media comprising continuous fine fibers (Part F of this disclosure). In yet another exemplary embodiment, a filter media comprising an electrostatically charged filter media (Part B of this disclosure) can be combined with a glass-free filter media (Part D of this disclosure).

[0498] In some embodiments, the filter media (including, for example, the filter media contained in a filter element) is pleated.

[0499] Exemplary filter elements include flat-plate filters, cartridge filters, or other filter components. Examples of such filter elements are described in U.S. Patent Nos. 6,746,517; 6,673,136; 6,800,117; 6,875,256; 6,716,274; and 7,316,723.

[0500] Other exemplary filter elements include those that can be incorporated into the face shield of a surgical mask, a filtering respirator, a reusable respirator, or a powered air-purifying respirator. In some embodiments, the filter element includes a filter medium that has been folded, sewn, and / or thermally welded.

[0501] Plate filter

[0502] In various embodiments, the filter media described herein can be incorporated into filter elements used in a filtration system. For example, the filter media can be used to form a plate filter element. Figure 13 A perspective view of an exemplary plate filter element 80 is depicted, and Figure 14 An exemplary cross-sectional view of a plate filter element 80 is depicted. The plate filter element 80 may be constituted by a filter medium 82 consistent with the technology disclosed herein. The filter medium 82 has an upstream side 86 and a downstream side 88 of the plate filter element 80. A frame member 84 is generally fixed to the periphery of the filter medium 82. The frame member 84 is generally hermetically coupled to the filter medium 82 around its periphery. In various embodiments, the periphery of the filter medium is fixed in the frame member 84 with epoxy resin or other adhesive.

[0503] In the current example, the filter medium 82 is pleated. Specifically, the filter medium 82 defines a first set of pleated folds 85 forming a first surface of the plate filter element 80. The filter medium 82 defines a second set of pleated folds 87 forming a second surface of the plate filter element 80. The filter medium 82 extends back and forth between the first set of pleated folds 85 and the second set of pleated folds 87. Fluid flows into the plate filter element 80 through one surface and then flows out from the opposite surface.

[0504] Although plate filters have been described, it should be understood that filter media manufactured according to the currently disclosed technology can be assembled into various shapes and configurations, including cylindrical and conical filters. In cylindrical or conical filters, the filter media can be pleated and is typically formed as a tube or cone (or a section of a tube or cone), wherein a first side of the pleated media (defined by a first set of pleats) forms the inner side, and a second side of the pleated media (defined by a second set of pleats) forms the outer side. In the case of cylindrical and conical filters used for air filtration, air typically flows into the filter element from the outside to the inside or from the inside to the outside.

[0505] Intake airflow and cabin air filtration

[0506] In some embodiments, the filter media described herein may be incorporated into filter elements to remove some or all particulate material from an airflow. For example, airflow entering a motor vehicle cabin, air from a computer disk drive, HVAC air, portable air purifiers (also known as personal air purifiers), cleanroom ventilation, and applications using filter bags, barrier fabrics, woven materials, airflow entering a motor vehicle's engine or generator, and airflow entering various combustion chambers typically contain particulate material. In the case of cabin air filters, it is desirable to remove particulate matter for passenger comfort and / or for aesthetic purposes. For airflow entering engines and combustion chambers, it is desirable to remove particulate material because particulates can cause substantial damage to the internal operation of the various mechanisms involved.

[0507] In some embodiments, the filter media incorporated into the filter element to remove some or all of the particulate material from an airflow may preferably comprise a layer of fine fibers. It is not desirable to be bound by theory, but it is believed that adding a layer of fine fibers can result in increased filter efficiency or extended lifespan when subjected to pulsed conditions.

[0508] Filtration of other liquids

[0509] Other (non-air) fluid flows may also carry particulate materials. Non-air fluid flows may include, for example, fuel, hydraulic oil, process water, air, diesel engine fluid (DEF), diesel engine lubricating oil, blow-by gas, and combinations thereof. For example, methods using filter media or composite materials as described herein may include passing a liquid flow containing contaminants through the filter media or composite material and removing the contaminants from the liquid flow.

[0510] In some embodiments, the filter media described herein may be incorporated into a filter element to remove some or all particulate material from a fluid flow.

[0511] Without being bound by theory, it is believed that the media described herein, particularly those containing at least one PET fiber with a diameter between that of glass fiber and microfibrillated cellulose fiber and that of bicomponent fiber, will exhibit increased end-of-life performance due to increased structural stability.

[0512] In some filter media that include glass fibers and bicomponent fibers but without resin, fiber migration has been observed during use, resulting in changes in pore size and, in some cases, reduced efficiency over the filter's lifespan. As mentioned above, it is believed that using fibers with diameters between those of glass fibers and microfibrillated cellulose fibers and those of bicomponent fibers can help prevent fiber migration during media use, thereby improving end-of-life performance.

[0513] Pleats

[0514] In some embodiments, the filter medium or filter element as described herein may be pleated.

[0515] Surprisingly, the media described herein, particularly those containing at least one PET fiber with a diameter between that of glass fiber and microfibrillated cellulose fiber and that of bicomponent fiber, have been found to exhibit sufficient tensile strength for pleating without the use of additional sparse cloth or support layers or resin.

[0516] In various embodiments, the filter media disclosed herein are self-supporting, meaning that when subjected to pleating, the filter media exhibits stiffness that allows it to maintain its pleated configuration under gravity and / or forces experienced during filtration operation. In various embodiments, the filter media can advantageously be self-supporting without any loose fabric layers. For example, as described above, in some embodiments, the stiffness of the filter media can be quantified using Gurley stiffness, which can be at least 2000 mg. In some embodiments, the filter media can be sufficiently flexible that it can pleat without breaking or cracking.

[0517] Pleating is a commonly known operation. In various embodiments, the filter medium is fed from a roller to a pleating machine, where it is folded to define a first set of pleats defining a first side and a second set of pleats defining a second side. The pleating machine can be a knife-type pleating machine, but other devices may also be used. In some embodiments, heating is not necessary when folding the filter medium, while in some other embodiments, heating the filter medium may be necessary during pleating. After folding, the filter medium is fed out of the pleating machine. The filter medium may be cut at a cutting station, where it is cut into segments of desired length, typically corresponding to the desired size of the filter element obtained at a particular pleat density.

[0518] Exemplary filter media include filter media made of microfibrillated cellulose.

[0519] A1 is a filter medium comprising a fiber layer including: microfibrillated cellulose fibers; glass fibers; and multi-component adhesive fibers.

[0520] Aspect A2 is the filter medium of aspect A1, wherein glass fibers form a gradient from a high concentration at one main surface of the fiber layer to few or no glass fibers at the other main surface of the fiber layer.

[0521] Aspect A3 is the filter medium of aspect A2, wherein the filter medium comprises two fiber layers, each fiber layer comprising microfibrillated cellulose fibers, glass fibers and multi-component adhesive fibers; and further wherein the two layers are oriented such that the main surfaces having a high glass concentration are adjacent to each other.

[0522] Aspect A4 is the filter medium of any one of aspects A1 to A3, wherein microfibrillated cellulose fibers and multi-component fibers are uniformly distributed throughout the fiber medium.

[0523] Aspect A5 is a filter medium of any one of aspects A1 to A4, wherein the multi-component fiber comprises at least one component, which is a thermoplastic polymer for thermal bonding with other fibers in the medium.

[0524] Aspect A6 is the filter medium of any one of aspects A1 to A5, wherein the multi-component fibers include bi-component fibers.

[0525] Aspect A7 is the filter medium of any one of aspects A1 to A6, wherein the filter medium further includes PET fibers, dyed fibers, conductive fibers or combinations thereof.

[0526] Aspect A8 is the filter media of aspect A7, wherein the PET fibers include PET fibers with a diameter in the range of 2 µm to 3 µm; crimped PET fibers; and / or dyed PET fibers.

[0527] Aspect A9 is the filter medium of any one of aspects A1 to A8, wherein the nonwoven filter medium further includes a layer of fine fibers.

[0528] Aspect A10 is the filter medium of aspect A9, wherein the fine fiber layer includes an electrospun layer, and the fine fibers have been directly deposited on the fiber medium by electrospinning.

[0529] Aspect A11 is a filter medium of any one of aspects A1 to A10, wherein microfibrillated cellulose fibers are present in an amount of 1 wt% to 49 wt% based on the total weight of the fiber medium; glass fibers are present in an amount of 10 wt% to 80 wt% based on the total weight of the fiber medium; and / or multi-component fibers are present in an amount of 10 wt% to 80 wt% based on the total weight of the fiber medium.

[0530] Aspect A12 is a filter medium of any one of aspects A1 to A11, wherein microfibrillated cellulose fibers are present in an amount of 1 wt-% to 49 wt-% based on the total weight of the fiber medium; wherein multi-component fibers are present in an amount of 10 wt-% to 80 wt-% based on the total weight of the fiber medium; and wherein the fiber medium comprises two main surfaces and glass fibers are present on one main surface in an amount of 10 wt-% to 80 wt-% based on the total weight of the fiber medium, and on the other main surface in an amount of 0 wt-% to 10 wt-% based on the total weight of the fiber medium.

[0531] Aspect A13 is the filter media of any of Aspects A1 to A12, wherein the filter media exhibits an efficiency of at least 80%, at least 85%, at least 90%, at least 95%, at least 97%, at least 98%, or at least 99% for 0.3 micron particles at a flow rate of 10 feet per minute (FPM).

[0532] Aspect A14 is the filter media of any one of Aspects A1 to A13, wherein the filter media exhibits performance of at least 1 ft in 0.5 inches of water. 3 / ft 2 / min, at least 2 ft underwater at 0.5 inches. 3 / ft 2 / min, at least 5 ft underwater at 0.5 inches. 3 / ft 2 / min, at least 10 ft underwater at 0.5 inches. 3 / ft 2 / min, at least 15 ft underwater at 0.5 inches. 3 / ft 2 / min or at least 20 ft underwater at 0.5 inches. 3 / ft 2 / min air transmittance; and / or up to 30 ft underwater at 0.5 inches. 3 / ft 2 / min, up to 50 ft at a depth of 0.5 inches. 3 / ft 2 / min, or up to 100 ft at a depth of 0.5 inches underwater. 3 / ft 2 / min air transmittance. This air transmittance is measured according to ASTM D737-18, entitled "Test Method for Air Permeability of Textile Fabrics".

[0533] A15 is the filter medium of any one of A1 to A14, wherein the filter medium exhibits a value of at least 10 g / m³. 2 At least 20 g / m 2 At least 25 g / m 2 At least 30 g / m 2 At least 35 g / m 2 At least 40 g / m 2 At least 50 g / m 2 At least 60 g / m 2 Or at least 70 g / m 2 Dry basis weight; and / or up to 100 g / m 2 Up to 120 g / m 2 Up to 140 g / m 2 Up to 150 g / m 2 Up to 160 g / m 2 Up to 180 g / m 2 Up to 200 g / m 2 Up to 300 g / m 2 or up to 400 g / m 2 Dry basis weight.

[0534] Aspect A16 is a filter medium of any one of aspects A1 to A15, wherein the filter medium exhibits a thickness of at least 100 micrometers, at least 150 micrometers, at least 0.2 mm, at least 0.25 mm, at least 0.3 mm, at least 0.35 mm, or at least 0.4 mm; and / or a thickness of up to 1 mm, up to 1.1 mm, up to 1.2 mm, up to 1.3 mm, up to 1.4 mm, or up to 1.5 mm, up to 4 inches (10.2 cm), or up to 5 mm.

[0535] Aspect A17 is the filter medium of any one of aspects A1 to A16, wherein the filter medium exhibits a Gurley stiffness of at least 2000 mg.

[0536] Aspect A18 is a filter medium according to any one of aspects A1 to A17, wherein the filter medium conforms to the NIOSH P95, NIOSH P99, NIOSH P100, NIOSH N95, NIOSH N99 and / or NIOSH N95 classification, as compiled in 42 CFR §84.

[0537] Aspect A19 is a filter medium according to any one of A1 to A18, wherein the filter medium exhibits a submicron-specific efficiency as defined by ASTM F2100-19 for Class 1, Class 2 and / or Class 3 barriers.

[0538] Aspect A20 is a method for filtering a liquid stream, the method comprising: passing a liquid stream containing contaminants through a filter medium, the filter medium comprising any one of aspects A1 to A19; and removing contaminants from the liquid stream.

[0539] Aspect A21 is the method of aspect A20, wherein the liquid flow includes air.

[0540] Exemplary filter media include filter media with electrostatic charges.

[0541] Aspect B1 is a filter medium comprising a support layer, a fine fiber layer in contact with the support layer, and a filter medium carrying an electrostatic charge.

[0542] Aspect B2 is the filter medium of aspect B1, wherein the electrostatically charged filter medium has a first main surface and a second main surface, and wherein the first main surface is in contact with the fine fiber layer.

[0543] Aspect B3 is the filter medium of aspect B1 or B2, wherein the filter medium is configured to allow air to pass through an electrostatically charged filter medium, then through a fine fiber layer, and then through a support layer.

[0544] Aspect B4 is the filter medium of any one of aspects B1 to B3, and the filter medium further includes a second support layer.

[0545] Aspect B5 is the filter medium of aspect B4, wherein the second support layer is in contact with the second main surface of the filter medium carrying electrostatic charge.

[0546] Aspect B6 is the filter medium of any one of aspects B1 to B5, wherein the electrostatically charged filter media includes polypropylene and acrylic fiber.

[0547] Aspect B7 is the filter medium of any one of aspects B4 to B6, wherein the electrostatically charged filter medium covers all or part of the second support layer.

[0548] Aspect B8 is a filter medium of any one of aspects B1 to B7, wherein the fine fiber layer includes fine fibers, including nanofibers.

[0549] Aspect B9 is a filter medium of any one of aspects B1 to B8, wherein the fine fiber layer includes fine fibers comprising a fiber-forming polymer material.

[0550] Aspect B10. A filter medium comprising a first support layer and a second support layer, a first fine fiber layer in contact with the first support layer, and a second fine fiber layer in contact with the second support layer, wherein the first fine fiber layer and the second fine fiber layer are adjacent to each other.

[0551] Aspect B11 is a filter medium comprising a support layer, a fiber layer in contact with the support layer, and an electrostatically charged filter medium having a first main surface and a second main surface, the first main surface being in contact with the fiber layer.

[0552] Aspect B12 is a filter medium of any of aspects B1 to B11, wherein the filter medium conforms to the NIOSH P95, NIOSH P99, NIOSH P100, NIOSH N95, NIOSH N99 and / or NIOSH N95 classifications, as compiled in 42 CFR § 84.

[0553] Aspect B13 is the filter medium of any of Aspects B1 to B12, wherein the filter medium exhibits a submicron-specific efficiency as defined by ASTM F2100-19 for Class 1, Class 2 and / or Class 3 barriers.

[0554] Aspect B14 is a method for filtering a liquid stream, the method comprising: passing a liquid stream containing contaminants through a filter medium, the filter medium comprising any one of aspects B1 to B13; and removing contaminants from the liquid stream.

[0555] Aspect B15 is a method of aspect B14, wherein the liquid flow includes air.

[0556] Regarding exemplary filter media ~ Regarding glass-free filter media

[0557] C1 is a nonwoven filter medium comprising: 25 wt% to 85 wt% of bicomponent fibers having a fiber diameter in the range of 5 micrometers to 25 micrometers and a fiber length in the range of 0.1 cm to 15 cm; 5 wt% to 50 wt% of low-efficiency fibers having a fiber diameter of at least 0.1 micrometers and less than 1 micrometer; 10 wt% to 50 wt% of high-efficiency fibers having a fiber diameter in the range of 1 micrometer to 5 micrometers; and 5 wt% to 25 wt% of microfibrillated fibers, wherein most of the microfibrillated fibers have a transverse dimension of up to 4 micrometers; wherein the nonwoven filter medium is substantially free of glass fibers.

[0558] Aspect C2 is the nonwoven filter media of aspect C1, comprising: 25 wt% to 75 wt% of bicomponent fibers; 10 wt% to 50 wt% of low-efficiency fibers; 10 wt% to 25 wt% of high-efficiency fibers; or 10 wt% to 25 wt% of microfibrillated fibers; or combinations thereof.

[0559] Aspect 3 is the nonwoven filter medium of aspect C1 or aspect C2, where wt% is based on the total weight of bicomponent fibers, low-efficiency fibers, high-efficiency fibers and microfibrillated cellulose fibers.

[0560] Aspect C4 is a nonwoven filter medium of any one of aspects C1 to C3, wherein the bicomponent fiber comprises a structural polymer portion and a thermoplastic binder polymer portion, wherein the melting point of the structural polymer portion is higher than the melting point of the binder polymer portion.

[0561] Aspect C5 is a nonwoven filter medium of aspect C4, wherein the structural polymer portion of the bicomponent fiber has a melting point of at least 240°C and the binder polymer portion of the bicomponent fiber has a melting point of up to 115°C.

[0562] Aspect C6 is a nonwoven filter medium of aspect C4, wherein the structural polymer portion of the bicomponent fiber has a melting point of at least 240°C and the adhesive polymer portion of the bicomponent fiber has a melting point in the range of 100°C to 190°C.

[0563] Aspect C7 is a nonwoven filter medium of aspect C6, wherein the binder polymer portion of the bicomponent fibers has a melting point in the range of 140°C to 160°C.

[0564] Aspect C8 is a nonwoven filter medium of any one of aspects C4 to C7, wherein the structural polymer portion is the core of a bicomponent fiber and the sheath is the thermoplastic binder polymer portion of the bicomponent fiber.

[0565] Aspect C9 is a nonwoven filter media of any one of aspects C4 to C8, wherein the structural polymer portion comprises polyethylene terephthalate (PET) and the thermoplastic adhesive polymer portion comprises coPET.

[0566] Aspect C10 is a nonwoven filter medium of any one of aspects C1 to C9, wherein the bicomponent fibers include a first bicomponent fiber and a second bicomponent fiber.

[0567] Aspect C11 is a nonwoven filter medium of any one of aspects C1 to C10, wherein the low-efficiency fibers have a fiber diameter of at least 0.4 micrometers and less than 1 micrometer.

[0568] Aspect C12 is a nonwoven filter medium of any one of aspects C1 to C11, wherein the low-efficiency fibers have a fiber diameter in the range of 0.6 micrometers to 0.8 micrometers.

[0569] Aspect C13 is a nonwoven filter medium of any one of aspects C1 to C12, wherein the low-efficiency fibers have a fiber diameter of 0.7 micrometers.

[0570] Aspect C14 is a nonwoven filter medium of any one of aspects C1 to C13, wherein the low-efficiency fibers have a length in the range of 1 mm to 15 mm.

[0571] Aspect C15 is a nonwoven filter medium of any one of aspects C1 to C14, wherein the low-efficiency fibers include polyethylene terephthalate (PET).

[0572] Aspect C16 is a nonwoven filter medium of any one of aspects C1 to C15, wherein the high-efficiency fibers have a fiber diameter in the range of 2 micrometers to 4 micrometers.

[0573] Aspect C17 is a nonwoven filter medium of any one of aspects C1 to C16, wherein the high-efficiency fibers include polyethylene terephthalate (PET).

[0574] Aspect C18 is a nonwoven filter medium of any of aspects C1 to C17, wherein most of the microfibrils have a transverse dimension of up to 2 micrometers.

[0575] Aspect C19 is a nonwoven filter medium of any of aspects C1 to C18, wherein most of the microfibrils have a transverse dimension in the range of 0.5 micrometers to 1.5 micrometers.

[0576] Aspect C20 is a nonwoven filter medium of any one of aspects C1 to C19, wherein microfibrillated fibers include microfibrillated cellulose fibers.

[0577] Aspect C21 is a nonwoven filter medium of any one of aspects C1 to C20, wherein the nonwoven filter medium has a solidity in the range of 5% to 15%.

[0578] Aspect C22 is a nonwoven filter medium of any one of aspects C1 to C21, wherein the nonwoven filter medium has a density of 24 g / m³. 2 Up to 100 g / m 2 Basis weight within the range.

[0579] Aspect C23 is a nonwoven filter medium of any one of aspects C1 to C22, wherein the nonwoven filter medium has a pore size in the range of 0.5 micrometers to 20 micrometers.

[0580] Aspect C24 is a nonwoven filter medium of any one of aspects C1 to C23, wherein the nonwoven filter medium has a P95 / P50 ratio of at least 1.5 or at least 2.

[0581] Aspect C25 is a nonwoven filter medium of any one of aspects C1 to C24, wherein the nonwoven filter medium has a P95 / P50 ratio of up to 3.

[0582] Aspect C26 is a nonwoven filter medium of any one of aspects C1 to C25, wherein the nonwoven filter medium has a thickness in the range of 0.12 mm to 1 mm.

[0583] Aspect C27 is a nonwoven filter medium of any one of aspects C1 to C26, wherein the nonwoven filter medium has a filtration efficiency of 1 ft underwater at a depth of 0.5 inches. 3 / ft 2 / min to 100 ft at 0.5 inches underwater 3 / ft 2 Transmittance within a range of / min.

[0584] Aspect C28 is a nonwoven filter medium of any one of aspects C1 to C27, wherein the nonwoven filter medium is substantially free of resin.

[0585] Aspect C29 is a nonwoven filter medium of any one of aspects C1 to C28, wherein the nonwoven filter medium does not contain glass fibers.

[0586] Aspect C30 is a nonwoven filter medium of any one of aspects C1 to C29, wherein the low-efficiency fiber comprises polyethylene terephthalate (PET), and wherein the PET of the low-efficiency fiber has a melting point of at least 250°C, at least 275°C, or at least 290°C.

[0587] Aspect C31 is a nonwoven filter medium of any one of aspects C1 to C30, wherein the high-efficiency fiber comprises polyethylene terephthalate (PET), and wherein the PET of the high-efficiency fiber has a melting point of at least 250°C, at least 275°C, or at least 290°C.

[0588] Aspect C32 is a method for filtering a liquid stream, the method comprising: passing a liquid stream containing contaminants through a nonwoven filter medium, the nonwoven filter medium comprising any one of aspects C1 to C31; and removing contaminants from the liquid stream.

[0589] Aspect C33 is a method of aspect C32, wherein the liquid flow includes fuel, hydraulic oil, process water, air, diesel engine fluid (DEF), diesel engine lubricating oil or blow-by gas, or a combination thereof.

[0590] Aspect C34 is a method of aspect C32, wherein the liquid flow includes air.

[0591] Exemplary composite materials

[0592] Aspect D1 is a composite material comprising: a first nonwoven filter medium comprising: 40 wt-% to 90 wt-% of a first bicomponent fiber having a fiber diameter in the range of 5 micrometers to 50 micrometers and a fiber length of 0.1 cm to 15 cm; 0 wt-% to 25 wt-% of a first high-efficiency fiber having a fiber diameter in the range of 1 micrometer to 5 micrometers; and 10 wt-% to 60 wt-% of a first microfibrillated fiber, wherein most of the microfibrillated fibers have a transverse dimension of up to 4 micrometers; optionally, a second nonwoven filter medium comprising: 40 wt-% to 90 wt-% of a second bicomponent fiber having a fiber diameter in the range of 5 micrometers to 50 micrometers and a fiber length of 0.1 cm to 15 cm; 0 wt-% to 25 wt-% of a second high-efficiency fiber; and 10 wt-% to 60 wt-% of a first microfibrillated fiber. The composite material comprises wt% of a second microfibrillated fiber, wherein most of the microfibrillated fibers have a transverse dimension of up to 4 micrometers; and a third nonwoven filter medium comprising small efficiency fibers having a fiber diameter of at least 0.1 micrometers and less than 1 micrometer; wherein the composite material is substantially free of glass fibers.

[0593] Aspect D2 is a composite material of aspect D1, wherein the first bicomponent fiber comprises a structural polymer portion and a thermoplastic binder polymer portion, wherein the structural polymer portion has a higher melting point than the binder polymer portion.

[0594] Aspect D3 is a composite material of aspect D1 or D2, wherein the second bicomponent fiber comprises a structural polymer portion and a thermoplastic binder polymer portion, wherein the structural polymer portion has a higher melting point than the binder polymer portion.

[0595] Aspect D4 is a composite of aspect D2 or D3, wherein the structural polymer portion of the bicomponent fiber has a melting point of at least 240°C and the binder polymer portion of the bicomponent fiber has a melting point of up to 115°C.

[0596] Aspect D5 is a composite material of aspect D2 or D3, wherein the structural polymer portion of the bicomponent fiber has a melting point of at least 240°C and the binder polymer portion of the bicomponent fiber has a melting point in the range of 110°C to 190°C.

[0597] Aspect D6 is a composite material of any one of aspects D1 to D5, wherein the first bicomponent fiber or the second bicomponent fiber comprises at least two different bicomponent fibers.

[0598] Aspect D7 is a composite material of any one of aspects D1 to D6, wherein the first nonwoven filter medium comprises 40 wt% to 60 wt% of a first bicomponent fiber.

[0599] Aspect D8 is a composite material according to any one of aspects D1 to D7, wherein the second nonwoven filter medium comprises 40 wt% to 60 t% of a second bicomponent fiber.

[0600] Aspect D9 is a composite material of any one of aspects D1 to D8, wherein the first high-efficiency fiber has a fiber diameter of 2.7 micrometers.

[0601] Aspect D10 is a composite material of any one of aspects D1 to D9, wherein the most efficient fiber includes PET.

[0602] Aspect D11 is a composite material of any one of aspects D1 to D10, wherein the second most efficient fiber has a fiber diameter of 2.7 micrometers.

[0603] Aspect D12 is a composite material of any one of aspects D1 to D11, wherein the second most efficient fiber includes PET.

[0604] Aspect D13 is a composite material of any one of aspects D1 to D12, wherein most of the microfibrillated fibers of the first nonwoven filter medium have a transverse dimension of up to 2 micrometers.

[0605] Aspect D14 is a composite material of any one of aspects D1 to D13, wherein most of the microfibrils of the second nonwoven filter media have a transverse dimension of up to 2 micrometers.

[0606] Aspect D15 is a composite material of any one of aspects D1 to D14, wherein most of the microfibrillated fibers of the first nonwoven filter medium have a transverse dimension in the range of 0.5 micrometers to 1.5 micrometers.

[0607] Aspect D16 is a composite material of any one of aspects D1 to D15, wherein most of the microfibrillated fibers of the second nonwoven filter media have a transverse dimension in the range of 0.5 micrometers to 1.5 micrometers.

[0608] Aspect D17 is a composite material of any one of aspects D1 to D16, wherein the first nonwoven filter medium comprises 10 wt% to 40 wt% of the first microfibrillated fiber, or wherein the second nonwoven filter medium comprises 10 wt% to 40 wt% of the second microfibrillated fiber.

[0609] Aspect D18 is a composite material of any one of aspects D1 to D17, wherein the first microfibrillated fiber comprises microfibrillated cellulose fiber, or wherein the second microfibrillated fiber comprises microfibrillated cellulose fiber, or the first microfibrillated fiber comprises microfibrillated cellulose fiber and the second microfibrillated fiber comprises microfibrillated cellulose fiber.

[0610] Aspect D19 is a composite material of any one of aspects D1 to D18, wherein the first nonwoven filter medium has a solidity in the range of 5% to 15%.

[0611] Aspect D20. A composite material of any one of aspects D1 to D19, wherein the first nonwoven filter medium has a density of 24 g / m³. 2 Up to 100 g / m 2 Basis weight within the range.

[0612] Aspect D21 is a composite material of any one of aspects D1 to D20, wherein the first nonwoven filter medium has a pore size of 0.5 micrometers to 20 micrometers.

[0613] Aspect D22 is a composite material of any one of aspects D1 to D21, wherein the first nonwoven filter medium has a thickness in the range of 0.12 mm to 1 mm.

[0614] Aspect D23 is a composite material of any one of aspects D1 to D22, wherein the first nonwoven filter medium has a filtration efficiency of 1 ft underwater at 0.5 inches. 3 / ft 2 / min to 100 ft at 0.5 inches underwater 3 / ft 2 Transmittance within a range of / min.

[0615] Aspect D24 is a composite material of any one of aspects D1 to D23, wherein the second nonwoven filter medium has a solidity in the range of 5% to 15%.

[0616] Aspect D25 is a composite material of any one of aspects D1 to D24, wherein the second nonwoven filter medium has a content of 24 g / m 2 Up to 100 g / m 2 Basis weight within the range.

[0617] Aspect D26 is a composite material of any one of aspects D1 to D25, wherein the second nonwoven filter medium has a pore size of 0.5 micrometers to 20 micrometers.

[0618] Aspect D27 is a composite material of any one of aspects D1 to D26, wherein the second nonwoven filter medium has a thickness in the range of 0.12 mm to 1 mm.

[0619] Aspect D28 is a composite material of any one of aspects D1 to D27, wherein the second nonwoven filter media has a filtration efficiency of 1 ft underwater at 0.5 inches. 3 / ft 2 / min to 100 ft at 0.5 inches underwater 3 / ft 2 Transmittance within a range of / min.

[0620] Aspect D29 is a composite material of any one of aspects D1 to D28, wherein the low-efficiency fiber has a fiber diameter of at least 0.4 micrometers and less than 1 micrometer or in the range of 0.6 micrometers to 0.8 micrometers.

[0621] Aspect D30 is a composite material of any one of aspects D1 to D29, wherein the low-efficiency fiber has a fiber diameter of 0.7 micrometers.

[0622] Aspect D31 is a composite material of any one of aspects D1 to D30, wherein the low-efficiency fiber includes polyethylene terephthalate (PET).

[0623] Aspect D32 is a composite material of any one of aspects D1 to D31, wherein the composite material is substantially resin-free.

[0624] Aspect D33 is a composite material of any one of aspects D1 to D32, wherein the composite material does not contain glass fiber.

[0625] Aspect D34 is a composite material of any one of aspects D1 to D33, wherein the first nonwoven filter medium, the second nonwoven filter medium and the third nonwoven filter medium are discrete layers.

[0626] Aspect D35 is a composite material of any one of aspects D1 to D34, wherein a nonwoven filter medium is configured to allow liquid to pass through a first nonwoven filter medium, then through a second nonwoven filter medium, and then through a third nonwoven filter medium.

[0627] Aspect D36 is a composite material of any one of aspects D1 to D35, and the nonwoven filter media further includes a support layer.

[0628] Aspect D37 is a composite material of aspect D36, and the support layer includes a porous polymer material.

[0629] Aspect D38 is a composite material of aspect D36 or D37, wherein a nonwoven filter medium is configured to allow liquid to pass through a first nonwoven filter medium, then through a second nonwoven filter medium, then through a third nonwoven filter medium, and then through a support layer.

[0630] Aspect D39 is a composite material of any one of aspects D1 to D38, wherein a first nonwoven filter medium is in contact with a second nonwoven filter medium, and the second nonwoven filter medium is in contact with a third nonwoven filter medium.

[0631] Aspect D40 is a composite material of any one of aspects D36 to D39, wherein the third nonwoven filter medium is in contact with the support layer.

[0632] Aspect D41 is a composite material of any one of aspects D1 to D40, wherein the first high-efficiency fiber comprises PET and the PET has a melting point of at least 250°C, at least 275°C or at least 290°C; or wherein the second high-efficiency fiber comprises PET and the PET has a melting point of at least 250°C, at least 275°C or at least 290°C; or both.

[0633] Aspect D42 is a composite material of any one of aspects D1 to D41, wherein the composite material conforms to the NIOSH P95, NIOSH P99, NIOSH P100, NIOSH N95, NIOSH N99 and / or NIOSH N95 classifications, as compiled in 42 CFR § 84.

[0634] Aspect D43 is a composite material according to any one of aspects D1 to D42, wherein the composite material exhibits submicron-specific efficiency as defined by ASTM F2100-19 for Class 1, Class 2 and / or Class 3 barriers.

[0635] Exemplary methods for manufacturing and using composite materials

[0636] Aspect E1 is a method for filtering a liquid stream, the method comprising: passing a liquid stream containing contaminants through a composite material comprising any one of aspects D1 to D43; and removing the contaminants from the liquid stream.

[0637] Aspect E2 is a method of aspect E1, wherein the liquid flow includes fuel, hydraulic oil, process water, air, diesel engine fluid (DEF), diesel engine lubricating oil or blow-by gas, or a combination thereof.

[0638] Aspect E3 is a method of aspect E1, wherein the liquid flow includes air.

[0639] Aspect E4 is the method of any one of aspects E1 to E3, wherein the liquid flow passes through a first nonwoven filter medium, then through a second nonwoven filter medium, and then through a third nonwoven filter medium.

[0640] Aspect E5. A method for manufacturing a composite material according to any one of aspects D1 to D43, the method comprising independently manufacturing a first nonwoven filter medium, a second nonwoven filter medium and a third nonwoven filter medium.

[0641] Aspect E6 is the method of aspect E5, wherein the first nonwoven filter medium, the second nonwoven filter medium and the third nonwoven filter medium are formed using a wet web forming process.

[0642] Aspect E7 is a method of aspect E5 or E6, which further includes placing a first nonwoven filter medium in contact with a second nonwoven filter medium and placing the second nonwoven filter medium in contact with a third nonwoven filter medium.

[0643] Aspect E8 is a method of aspect E7, which further includes bonding a first nonwoven filter medium to a second nonwoven filter medium, or bonding a second nonwoven filter medium to a third nonwoven filter medium, or both.

[0644] Aspect E9 is a method of aspect E8, wherein adhesion includes lamination.

[0645] Aspect E10 is a method of any one of aspects E5 to E9, the method further comprising placing a third nonwoven filter medium in contact with the support layer.

[0646] Exemplary filter media embodiment ~ Filter media including a continuous fine fiber layer

[0647] F1. A filter medium comprising a support layer, a continuous layer of fine fibers, and an optional efficiency layer.

[0648] Aspect F2 is the filter medium of aspect F1, wherein the continuous fine fiber layer has a thickness of up to 50 µm.

[0649] Aspect F3 is a filter medium of aspect F1 or F2, wherein the composite material comprising a support layer and a continuous fine fiber layer has a P95 / P50 ratio of up to 1.8, up to 1.9 or up to 2; wherein the efficiency layer has a P95 / P50 ratio of at least 1.8, at least 1.9 or at least 2; and wherein the P95 value of the composite material falls within the range provided by the P5 and P50 values ​​of the efficiency layer.

[0650] Aspect F4 is a filter medium of any one of aspects F1 to F3, wherein the complex has a P95 / P50 ratio greater than 1.

[0651] Aspect F5 is any of the filter media in aspects F1 to F4, wherein the efficiency layer has a P95 / P50 ratio of up to 10, up to 15 or up to 20.

[0652] Aspect F6 is the filter medium of any one of aspects F1 to F5, wherein the continuous fine fiber layer has a thickness of at least 2 µm.

[0653] Aspect F7 is the filter medium of any one of aspects F1 to F6, wherein the thickness of the continuous fine fiber layer is measured by scanning electron microscopy (SEM).

[0654] Aspect F8 is the filter medium of any one of aspects F1 to F7, wherein a continuous fine fiber layer is located between the efficiency layer and the support layer.

[0655] Aspect F9 is the filter medium of any one of aspects F1 to F8, wherein the efficiency layer is located on the upstream side of the filter medium.

[0656] Aspect F10 is the filter medium of any one of aspects F1 to F9, wherein the filter medium further includes a second efficiency layer.

[0657] Aspect F11 is the filter medium of any of Aspect F10, wherein the second efficiency layer is adjacent to and upstream of the efficiency layer.

[0658] Aspect F12 is the filter medium of any one of aspects F1 to F11, wherein the efficiency layer includes wet-laid resin-free media, wet-laid resin-bonded glass media, melt-blown media, wet-laid cellulose media, or air-laid glass media.

[0659] Aspect F13 is the filter medium of any one of aspects F1 to F12, wherein the efficiency layer includes wet-laid media.

[0660] Aspect F14 is a filter medium of any one of aspects F1 to F13, wherein the efficiency layer comprises bicomponent fibers and efficiency fibers, wherein the diameter of the efficiency fibers is smaller than that of the bicomponent fibers.

[0661] Aspect F15 is any of the filter media in aspects F1 to F14, and the efficiency fiber includes glass fiber.

[0662] Aspect F16 is the filter media of any one of aspects F1 to F15, and the efficiency fibers include short-cut fine fibers.

[0663] Aspect F17 is the filter media of any one of aspects F1 to F16, wherein the efficiency layer includes microfibers.

[0664] Aspect F18 is a filter medium of any of aspects F1 to F17, wherein the continuous fine fibers have a diameter of up to 10 micrometers (µm).

[0665] Aspect F19 is a filter medium of any one of aspects F1 to F18, wherein the continuous fine fibers comprise fibers having a diameter of at least 1 micrometer.

[0666] Aspect F20 is a filter medium of any one of aspects F1 to F19, wherein the continuous fine fibers include fibers having an elliptical shape.

[0667] Aspect F21 is the filter medium of any one of aspects F1 to F20, wherein the continuous fine fibers comprise a mixture of fibers of different diameters.

[0668] Aspect F22 is the filter medium of aspect F21, in which fibers of different diameters are mixed in a single layer of continuous fine fiber layer.

[0669] Aspect F23 is a filter medium of aspect F21 or aspect F22, wherein fibers of different diameters form different layers in a continuous fine fiber layer.

[0670] Aspect F24 is the filter medium of any one of aspects F21 to F23, wherein the fibers of different diameters include large and small fibers, wherein the average diameter of the large fibers is at least 3 times the average fiber diameter of the small fibers.

[0671] Aspect F25 is the filter medium of aspect F24, wherein the continuous fine fiber layer includes: a first fine fiber layer comprising large fine fibers; and a second fine fiber layer comprising small fine fibers.

[0672] F26 is a filter medium for F24 or F25, wherein the fine fibers have an average diameter of at least 1 µm.

[0673] Aspect F27 is a filter medium of any one of aspects F24 to F26, wherein the diameter of the large fine fiber is at least 0.2 µm, at least 0.3 µm, or at least 0.4 µm larger than the diameter of the small fine fiber.

[0674] Aspect F28 is the filter media of any one of aspects F1 to F27, wherein the continuous fine fibers include polyamide.

[0675] Aspect F29 is a filter medium of any one of aspects F1 to F28, wherein the support layer includes a spunbond layer.

[0676] Aspect F30 is a filter medium of any one of aspects F1 to F29, wherein the fine fibers of the continuous fine fiber layer include nylon.

[0677] Aspect F31 is the filter medium of any one of aspects F1 to F30, wherein the fine fibers include a terpolymer comprising nylon-6, nylon-6,6 and nylon-6,10.

[0678] Aspect F32 is a filter media of any one of aspects F1 to F31, wherein the fine fibers comprise a terpolymer having a number average molecular weight of 21,500 to 24,800 and comprising 45% nylon-6, 20% nylon-6,6 and 25% nylon-6,10.

[0679] Aspect F33 is a filter medium of any one of aspects F1 to F32, wherein the fine fibers of the continuous fine fiber layer are not cross-linked.

[0680] Aspect F34 is a filter medium of any of aspects F1 to F33, wherein the filter medium conforms to the NIOSH P95, NIOSH P99, NIOSH P100, NIOSH N95, NIOSH N99 and / or NIOSH N95 classifications, as compiled in 42 CFR § 84.

[0681] Aspect F35 is a filter medium of any of aspects F1 to F34, wherein the filter medium exhibits a submicron-specific efficiency as defined by ASTM F2100-19 for Class 1, Class 2 and / or Class 3 barriers.

[0682] Aspect F36 is a filter element comprising a filter medium of any one of aspects F1 to F35.

[0683] Aspect F37 is a filter element of aspect F36, wherein the wire support is located downstream of the support layer.

[0684] Aspect F38 is a method for filtering a liquid stream, the method comprising: passing a liquid stream containing contaminants through a nonwoven filter medium, the nonwoven filter medium comprising any one of aspects F1 to F35; and removing contaminants from the liquid stream.

[0685] Aspect F39 is a method of aspect F38, wherein the liquid flow includes air.

[0686] Exemplary face mask system aspects

[0687] Aspect G1. A face mask system comprising a face mask defining a face container configured to receive a wearer's nose and mouth; a retaining feature configured to retain the face mask in position relative to the wearer; an air intake airflow path extending from the surrounding environment to the face container; and a filter element disposed across the air intake airflow path, wherein the filter element comprises a filter medium of any one of aspects A1 to A19, B1 to B13, C1 to C22, F1 to F37 or a composite material or combination thereof of any one of aspects D1 to D43.

[0688] Aspect G2. The mask system according to aspect G1, wherein the filter element includes one or more folds formed therein.

[0689] Aspect G3. The mask system according to aspect G1 or G2, wherein the retaining feature includes straps.

[0690] Aspect G4. A mask system according to any one of aspects G1 to G3, wherein the retaining feature includes a headband.

[0691] Aspect G5 is a mask system according to any one of aspects G1 to G3, wherein the mask includes a filter element.

[0692] Aspect G6 is a mask system according to any one of aspects G1 to G3, wherein the filter element is located away from the mask.

[0693] Aspect G7 is a mask system according to any one of aspects G1 to G4, wherein the mask is made of an airtight material defining an opening, wherein a filter element is positioned above the opening, and the mask system further includes an exhalation valve that defines an exhaust airflow path from the face container to the surrounding environment.

[0694] Aspect G8 is a mask system according to any one of aspects G1 to G4, wherein the mask system includes a filtering mask respirator, and wherein the filtering element forms at least a portion of the mask of the filtering mask respirator.

[0695] Aspect G9 is a mask system according to any one of aspects G1 to G4, wherein the mask system includes a surgical mask.

[0696] Aspect G10 is a mask system according to any one of aspects G1 to G3 and G5, wherein the mask system includes a powered air-purifying respirator, the powered air-purifying respirator including an airflow duct extending to the mask, wherein the airflow duct defines a portion of an intake airflow path.

[0697] The present invention 39 is illustrated by the following examples. It should be understood that specific examples, materials, quantities, and procedures should be interpreted broadly in accordance with the scope and spirit of the invention as set forth herein.

[0698] Example

[0699] All reagents, starting materials, and solvents used in the following examples were purchased from commercial suppliers (e.g., Sigma-Aldrich, St. Louis, Missouri) and, unless otherwise specified, can be used without further purification.

[0700] Sample preparation in Examples 1 to 4

[0701] 24-inch-wide fiber media samples are prepared by forming two feeds (see Tables 1A, 1B, 2A, and 2B), which are fed into a skewed double headbox. A method for forming such fiber media samples is described in U.S. Patent No. 9,885,154. An exemplary headbox is shown in Figure 1 of Patent No. 9,885,154.

[0702] The samples were dried in a float-type air oven (Advanced Systems, Inc., Green Bay, Wisconsin).

[0703] Test methods in Examples 1 to 4

[0704] Basis weight

[0705] Basis weight is measured according to ASTM D646-13, entitled "Standard Test Method for Mass Per Unit Area of ​​Paper and Paperboard of Aramid Papers (Basis Weight)".

[0706] Airflow / Air Transmission Rate Test

[0707] Air permeability (also known as Fraser air permeability or airflow) is measured according to ASTM D737-18, entitled "Test Method for Air Permeability of Textile Fabrics".

[0708] efficiency

[0709] Air filtration performance was evaluated using the High Efficiency Flat Plate (HEFS) TSI Automated Filter Tester, Model 8127, test bench (TSI Incorporated, Shoreview, Minnesota). Particle capture efficiency was measured by testing 4-inch diameter media samples with 0.3 µm oil (bis(2-ethylhexyl) sebacic acid ester (DEHS), Sigma-Aldrich) droplets (aerosol) at a flow rate of 14.7 L / min. The TSI CertiTest 8127 Automated Filter Tester is designed to test filters, respirator cartridges, and filter media according to the latest American government and industry-wide specification and conforms to 42 CFR § 84 (June 8, 1995).

[0710] Thickness test

[0711] In addition to using a foot pressure of 0.5 psi, the thickness is measured according to TAPPI T 411 om-15, under the name "Thickness (caliper) of paper, paperboard, and combined board".

[0712] Classification efficiency

[0713] Calculate the tiered efficiency using the following formula: , Where Feff = tiered efficiency; C 上 = Particle concentration upstream of the filter, and C 下 = Particle concentration downstream of the filter.

[0714] Medium characterization in Examples 5 to 9

[0715] Liquid filtration performance test

[0716] Calculate the effective pressure drop, medium velocity, capacity, and 4 µm Beta (β) using a circular plate as described below. 4µm ).

[0717] For examples 6 and 7

[0718] In addition to the hydraulic fluid load, which can replace ISO media test dust (ISO 12103-1, A2 fine test dust, Powder Technology, Inc., Ardennes, Minnesota), other test media can be used as described in ISO 16889:2008 (Hydraulic fluid power — Filters — Multi-pass method for evaluating filtration performance of a filter element). The media area is 0.0507 m². 2 The test flow rate was 2 L / min, and the test was conducted with a terminal element pressure differential of 200 kPa.

[0719] For examples 8 and 9

[0720] The test medium is as described in ISO 16889:2008 (Hydraulic fluid dynamics—Filters—Multiple-pass methods for evaluating the performance of filter elements). The medium area is 0.0507 m². 2 The test flow rate was 16 L / min, and the test was conducted with a terminal element pressure differential of 320 kPa.

[0721] Reality

[0722] The solidity (c) of a nonwoven layer (including, for example, a non-fiber layer or a composite material comprising both a fiber layer and a non-fiber layer) is calculated using the following equation: c = BW / ρZ, where BW is the basis weight, ρ is the fiber density, and Z is the thickness of the medium.

[0723] Measure thickness using the TAPPI T411 om-15, labeled "Thickness (caliper) of paper, paperboard, and combined board"; apply foot pressure of 1.5 psi. Measure basis weight using the TAPPI T410 om-08.

[0724] Materials and methods in Examples 10 to 17

[0725] Preparation of polymer solutions

[0726] To prepare solution 1, a nylon copolymer resin (SVP 651 (Shakespeare Co., Columbia, South Carolina), a terpolymer with a number-average molecular weight of 21,500 to 24,800 comprising 45% nylon-6, 20% nylon-6,6 and 25% nylon-6,10, also see Table 3) was dissolved in alcohol (ethanol, 190°C) and heated to 60°C to produce a 9% nylon solids solution. After cooling, a melamine-formaldehyde resin (CYMEL 1133, Cytec Industries, West Paterson, NJ) was added to the solution to achieve a 20:100 melamine-formaldehyde resin to nylon weight ratio. The melamine-formaldehyde resin acts as a crosslinking agent. Additionally, p-toluenesulfonic acid (7%, based on polymer solids) was added to the solution. The solution was stirred until homogeneous. Solution 1 was used to prepare 0.25 µm fibers.

[0727] Except for using a 17% nylon solid solution, solution 2 was prepared as described for solution 1 (and also resulted in a 20:100 weight ratio of melamine-formaldehyde resin to nylon). Solution 2 was used to prepare 1 µm fibers.

[0728] The viscosities of solutions 1 and 2, at 30 ± 5 cP and 300 ± 5 cP respectively, were measured using a Brookfield LV DV-IPrime viscometer with a Fisher Scientific 8005 temperature-controlled water bath at 25°C.

[0729] To prepare solution 3, the copolyamide (Griltex D 1523A, EMS-Griltech, Switzerland) was dissolved in a solvent mixture of ethanol, benzyl alcohol, and water (ethanol:benzyl alcohol:water, 16:1:1 by weight) and heated to 60°C to produce a 21% (w / w) solution. Solution 3 has a viscosity of 473 ± 10 cP (measured using a Brookfield LV DV-I Prime viscometer with a Fisher Scientific 8005 temperature-controlled water bath at 25°C). Solution 3 was used to prepare 1.4 µm fibers.

[0730] Sample preparation by hanging drop in Examples 10 to 14

[0731] Samples are prepared using a pendant drop device (i.e., a syringe filled with a polymer solution). A high voltage is applied to a needle attached to the syringe, and the polymer solution is pumped at a specified pump rate. As droplets of the polymer solution emerge from the needle, they form Taylor cones under the influence of an electrostatic field. At a sufficiently high voltage, a jet is emitted from the stretched Taylor cone and fine fibers are formed, which are deposited on a medium attached to a rotating mandrel that acts as a collector.

[0732] Fibers were formed on a support layer wound around a cylinder (with a diameter of 4 inches and rotating at 300 rpm) by electrospinning at 24 kV and 4 inches away from one or more syringes (delivering one or more polymer solutions at a pump rate of 0.075 mL / min). After electrospinning, the resulting fine fibers were heat-treated at 140°C for 10 minutes.

[0733] Method 1:

[0734] A mixed fiber layer was deposited on a substrate with a concentration of 70 g / m² by co-spinning two different electrospinning precursor solutions (solution 1 and solution 2) delivered from two different syringes at the same pump rate (0.075 mL / min) and for the same duration (5 min). 2 Two control samples were prepared separately using the same pump rate and duration to spin-dry solution 1 or solution 2 from a single syringe to produce layers containing only small or large fine fibers, respectively. The 0.2 mm thick spunbond nylon loose fabric (media grade 23200, Cerex Advanced Fibers, Cantonment, Florida) was spun on a basis weight and 28% solidity.

[0735] All samples underwent post-synthesis treatment to improve robustness through cross-linking. After electrospinning, the resulting fibers were heat-treated at 140°C for 10 minutes.

[0736] Method 2:

[0737] A series of mixed fiber layers were deposited on a substrate with 70 g / m² by co-spinning solutions 1 and 2 delivered from two different syringes at the same pump rate (0.075 mL / min) and for the same duration. 2The samples were prepared separately using a 0.2 mm thick spunbond nylon loose fabric (media grade 23200, Cyrex Advanced Fibers, Cantonmont, Florida) with a basis weight and 28% solidity. Two control samples were prepared separately by co-spinning solutions 1 or 2 from two different syringes to produce layers containing only fine or large fibers, respectively, using the same pump speed and duration. Co-spinning solutions 1 or 2 from two syringes (instead of one syringe) resulted in a more similar basis weight between the control samples and the samples containing mixed fiber layers, compared to Method 1.

[0738] All samples underwent post-synthesis treatment to improve robustness through cross-linking. After electrospinning, the resulting fibers were heat-treated at 140°C for 10 minutes.

[0739] Method 3:

[0740] A series of fiber layers with different diameters are deposited on a 0.2 mm thick spunbond nylon fabric with a basis weight of 70 g / m² by alternating (“pulsed”) spinning from one of two syringes containing solution 1 or solution 2. 2 The solidity was 28% (Media Grade 23200, Cyrex Advanced Fibers, Cantonmont, Florida), and the two syringes delivered at the same pump rate (0.075 mL / min) and alternated according to the timing sequence in Table 5.

[0741] All samples underwent post-synthesis treatment to improve robustness through cross-linking. After electrospinning, the resulting fibers were heat-treated at 140°C for 10 minutes.

[0742] Method 4:

[0743] A series of hybrid fiber structures were deposited using a two-step procedure on a substrate with a density of 70 g / m². 2 On a 0.2 mm thick spunbond nylon loose fabric with a basis weight and 28% density (medium grade 23200, Cyrex Advanced Fibers, Cantonmont, Florida).

[0744] In the first step, solution 2 was delivered continuously for 2 minutes at a pump rate of (0.075 mL / min) to transport the macrofibers (equivalent to 0.43 g / m²). 2 The coverage is deposited onto the loose fabric to act as a support layer for subsequent fibers.

[0745] In the second step, a layer of fine fibers of mixed diameter is deposited by spinning alternately (“pulsed”) from either of two syringes containing solution 1 or solution 2 (for small and large fine fibers, respectively), with the two syringes delivering at the same pump rate (0.075 mL / min) and alternating according to the timing sequence in Table 5.

[0746] All samples (with a concentration ranging from approximately 0.65 to 0.86 g / m³) 2 The total basis weight of the fibers is subjected to post-synthetic treatment to improve robustness through crosslinking. After electrospinning, the resulting fibers are heat-treated at 140°C for 10 minutes.

[0747] Method 5

[0748] A two-step procedure was used to deposit a series of structures with different basis weight contributions from the fine fiber component onto a substrate with a density of 70 g / m². 2 On a 0.2 mm thick spunbond nylon loose fabric with a basis weight and 28% density (medium grade 23200, Cyrex Advanced Fibers, Cantonmont, Florida).

[0749] In the first step, solution 2 was delivered continuously for 2 minutes at a pump rate of (0.075 mL / min) to transport the macrofibers (equivalent to 0.43 g / m²). 2 The coverage is deposited onto the loose fabric to act as a support layer for subsequent fibers.

[0750] In the second step, a layer of fine fibers was deposited by delivering solution 1 at a pump rate of 0.075 mL / min. The basis weight of the fine fiber layer was 0.09 g / m³. 2 0.10 g / m 2 0.22 g / m 2 0.31 g / m 2 0.45 g / m 2 or 0.56 g / m 2 This is achieved by using electrospinning durations of 48 seconds, 60 seconds, 120 seconds, 168 seconds, 240 seconds, or 300 seconds, respectively. After electrospinning, the resulting fibers are heat-treated at 140°C for 10 minutes.

[0751] Method 6

[0752] A series of media samples are fabricated, comprising multiple layers with various fine fiber sizes. The samples consist of a large fine fiber base layer, followed by a small fine fiber layer, and topped with a large fine fiber layer (large / small / large, or L / S / L). Alternatively, the samples consist of a large fine fiber base layer, followed by a small fine fiber layer, then a mixture of small and large fine fiber layers, and topped with a large fine fiber layer (large / small / mixed / large, or L / S / mixed / L).

[0753] By spinning solution 2 for 2 minutes, large and small fibers (equivalent to 0.43 g / m) are produced. 2 Coverage) was deposited onto the loosely woven fabric. Not wanting to be bound by theory, it is believed that the large microfibers act as a support layer beneath the subsequent fiber layers. Next, a second layer of small microfibers (equivalent to 0.22 g / m²) was deposited by spinning solution 1 for 2 minutes. 2 Coverage). If included, an intermediate (hybrid) layer comprising both fine and macrofibers is added by alternating (“pulsed”) spinning from a syringe containing either solution 5 or solution 2 (for microfibers and macrofibers, respectively) according to the timing sequence in Table 1. Finally, a top layer of macrofibers (equivalent to 0.43 g / m²) is deposited by spinning solution 2 for 2 minutes. 2 (Coverage). All solutions were delivered at a pump rate of 0.075 mL / min.

[0754] All samples (with a range of approximately 1.31 to 1.52 g / m³) 2 The total basis weight of the fibers is subjected to post-synthetic treatment to improve robustness through crosslinking. After electrospinning, the resulting fibers are heat-treated at 140°C for 10 minutes.

[0755] Method 7

[0756] A series of media samples were also prepared, including a base layer of macrofibers and a mixed layer of microfibers and macrofibers.

[0757] First, the solution containing macrofibers (equivalent to 0.43 g / m²) was spun for 2 minutes at a pump rate of 0.075 mL / min. 2 The first fine fiber layer (coverage) is deposited on a substrate with a density of 70 g / m². 2 The substrate was coated with a 0.2 mm thick spunbond nylon loose fabric (media grade 23200, Cyrex Advanced Fibers, Cantonmont, Florida) with a basis weight and 28% solidity. Next, a second microfiber layer containing a mixture of micro and macrofibers was deposited by co-spinning two different electrospinning precursor solutions (solution 1 and solution 2) delivered from two different syringes at the same pump rate (0.075 mL / min) and for the same duration (2.5 min or 4.5 min).

[0758] All samples underwent post-synthesis treatment to improve robustness through cross-linking. After electrospinning, the resulting fibers were heat-treated at 140°C for 10 minutes.

[0759] Method 8A

[0760] Single-sized fiber structures (nominal fiber diameter 1.4 µm, basis weight 0.67 g / m³) were produced by spinning at a 4-inch needle-to-collector distance under a 24 kV bias for 2.5 minutes from a polymer solution (ethanol: benzyl alcohol: water in a weight ratio of 16:1:1) of 21% w / w Griltex D 1523A (EMS-Griltech AG, Switzerland) (solution 3) delivered at a pump rate of 0.075 mL / min. 2 The coating (coverage) was deposited on a 0.2 mm thick spunbond nylon fabric with a basis weight of 70 g / m². 2 And the density is 28% (Media Grade 23200, Cyrex Advanced Fibers, Cantonmont, Florida).

[0761] Method 8B

[0762] Single-sized fiber structures (nominal fiber diameter 1 µm, basis weight 2.59 g / m²) were produced from a polymer solution (17% w / w SVP 651 in ethanol (see Table 3)) delivered at a pump rate of 0.075 mL / min for 12 minutes at a bias of 24 kV and a needle-to-collector distance. 2 The coating (coverage) was deposited on a 0.2 mm thick spunbond nylon fabric with a basis weight of 70 g / m². 2 And the density is 28% (Media Grade 23200, Cyrex Advanced Fibers, Cantonmont, Florida).

[0763] Method 8C

[0764] Single-sized fiber structures (nominal fiber diameter 1.4 μm, basis weight 4.02 g / m²) were produced by spinning at a 4-inch needle-to-collector distance under a 24 kV bias for 15 minutes from a polymer solution (ethanol:benzyl alcohol:water in a weight ratio of 16:1:1) of 21% w / w Griltex D 1523A (EMS-Griltech, Switzerland) (solution 3) delivered at a pump rate of 0.075 mL / min. 2 Coverage) deposited on nylon sparse fabric (Cerex, 70 g / m²) 2 )superior.

[0765] Method 9:

[0766] Large and fine fibers (equivalent to 0.54 g / m²) were produced by spinning solution 3 at a 4-inch needle-to-collector distance under a 24 kV bias for 2 minutes. 2 (Coverage) is deposited onto the sparse cloth.

[0767] Next, a second layer of fine fibers (equivalent to 0.22 g / m²) was deposited by spinning solution 1 at a 4-inch needle-to-collector distance under a 24 kV bias for 2 minutes. 2 (Coverage).

[0768] Next, a third large fine fiber layer (equivalent to 0.54 g / m²) was deposited by spinning solution 3 at a 4-inch needle-to-collector distance under a 24 kV bias for 2 minutes. 2 (Coverage).

[0769] Finally, a top layer of large fine fibers (equivalent to 0.54 g / m²) was deposited by spinning solution 3 at a 4-inch needle-to-collector distance under a 24 kV bias for 2 minutes. 2 (Coverage).

[0770] Table 5. Pulse electrospinning sequence

[0771]

[0772] *The proportion of larger fine fibers (based on fiber count) is estimated from the diameters of the small (solution 1) and large (solution 2) fine fibers, the percentage of solids in the precursor spinning solution, the syringe pump feed rate, and the spinning time, as described in the fiber proportion calculation section below.

[0773] Preparation of media hand-made sheets

[0774] Hand-formed sheets were prepared by weighing the bulk fibers to achieve the target basis weight required for forming 30 cm × 30 cm sheets. A FORMAX 12" × 12" stainless steel sheet mold (catalog number G-100, Adirondack Machine Corporation, Hudson-Forth, NY) was used as the hand-formed sheet molder, and preparation was achieved by placing a uniform, loosely woven nonwoven fabric layer with a pore size of less than 100 µm at the bottom of the molder (without using removable forming lines). The molder was then filled almost to full with cold tap water, leaving room for the addition of an additional 1.5 L of water. 1 mL of Tide HE laundry soap (Procter & Gamble, Cincinnati, OH) was added to the water in the hand-formed sheet molder. To prepare the fibers, 1 L of cold tap water was added to a Vitamix mixer along with 200 mL of a 5% acetic acid aqueous solution. The weighed fibers were added to the mixer and mixed at a medium-low speed for 180 seconds. The contents of the mixer are then added to the hand-formed sheet former, and the contents of the hand-formed sheet former are mixed to ensure uniform fiber distribution. Water is drained from the bottom of the hand-formed sheet former, allowing the fibers to form a sheet as they are collected on the nonwoven fabric. Water is removed from the sheet using vacuum suction on the line side, and the hand-formed sheet (still on the fabric) is dried for 10 minutes at 120°C on a single-sided hot plate rapid dryer (Model 135 rapid dryer, Emerson Apparatus, Golham, Maine). The sheet (from the fabric) is removed and allowed to cool to ambient conditions before use.

[0775] Medium characterization

[0776] Steady flow condition test

[0777] The Beta (β) ratio was evaluated under steady flow conditions using ISO 16889:2008 (Hydraulic fluid dynamics—Filters—Multiple-pass method for evaluating the filtration performance of filter elements), except when testing plate performance (running the test in single-pass mode instead of the multiple-pass mode required by the test standard). The test was run at 25°C instead of the 40°C required by the test standard. The flow rate through the medium was 5 mm / sec. An upstream particle concentration of 10 mg / L was provided using intermediate test dust (Powder Technology, Inc., Ardennes, Minnesota) according to ISO 12103-1. Continuous particle concentration measurements were collected every 6 seconds.

[0778] Circulating flow condition test

[0779] The β ratio was evaluated using ISO / CD 23369, Edition 1 (Hydraulic hydrodynamics—Multi-pass method for evaluating the filtration performance of filter elements under circulating flow conditions), except when testing plate performance (running the test in single-pass mode instead of the multi-pass mode required by the test standard). The test was run at 25°C instead of the 40°C required by the test standard. The flow rate through the medium was circulated between 5 mm / sec and 1.25 mm / sec in 10-second cycles (approximately 5 seconds at each speed). An upstream particle concentration of 10 mg / L was provided using intermediate test dust according to ISO 12103-1 (Powder Technology, Inc., Ardennes, Minnesota). Continuous particle concentration measurements were collected every 6 seconds. The fluid conductivity was controlled to the range of 1000 to 1500 pS / m.

[0780] Calibration of particle counter

[0781] The particle counter is calibrated according to ISO 11171:2016 (Hydraulic fluid power—Calibration of automatic particle counters for use in ISO test procedures).

[0782] pressure drop

[0783] Use the test conditions shown in Table 6, as described in ISO 3968:2017, to measure the pressure drop.

[0784] Table 6 - Pressure Drop Test Conditions

[0785] Dielectric area 0.0507 m² fluid viscosity 15 cSt fluid temperature 40°C

[0786] Scanning electron microscopy (SEM)

[0787] Samples for top-down SEM imaging are prepared by sputtering a gold and palladium mixture comprising an Au:Pd 60:40 mixture onto the surface. Typically, accelerating voltages of 5 kV or 10 kV are used, and images are acquired at magnifications of x500, x1000, and x2500 using a secondary electron detector or a backscattered electron detector.

[0788] The sample was prepared for cross-sectional SEM imaging using the following steps: a 3 mm × 20 mm sample comprising fine fibers on a support layer was prepared; the sample was placed fiber-side down in a weighing vessel on a hard surface; the vessel was filled with liquid nitrogen to immerse the sample. After at least 30 seconds, the sample was cut with a razor blade (while still immersed in liquid nitrogen) to expose the cross-section. After cutting and another 10 to 20 seconds, the sample was removed from the liquid nitrogen and mounted for SEM imaging. The sample was then coated with 60:40 Au:Pd sputtering. Typically, an accelerating voltage of 5 kV was used, and images were acquired at x1000 magnification using a secondary electron detector.

[0789] Fiber diameter

[0790] The fine fiber samples produced in Examples 1 through 7 have an average fiber diameter of no more than 10 micrometers. Typically, small fine fibers have an average fiber diameter ranging from 200 nm to 600 nm, as measured by scanning electron microscopy (SEM). Typically, large fine fibers have an average fiber diameter of at least 700 nm, as measured by scanning electron microscopy (SEM). Fiber size is determined by imaging the fibers via SEM and measuring the fiber diameter (or other dimensions of interest) in the resulting micrographs. Image processing software such as ImageJ and / or (FIJI Is Just ImageJ (FIJI), or updated versions of ImageJ) is used for fiber size determination.

[0791] Fine fiber layer thickness

[0792] The thickness of the fine fiber sample (prepared as described above) was measured by scanning electron microscopy (SEM) through cross-sectional analysis of the SEM. The thickness of the fine fiber layer was determined using FIJI from at least five images of different portions of the sample. Specifically, the top and bottom of the fine fiber layer were marked using a polygon tool, areas outside the selected fine fiber cross-section were cleared, the selected area of ​​the fine fiber cross-section was recolored white using a threshold level tool to compensate for fibers at the boundaries of the selected section, and the maximum thickness in the images was measured and recorded. Five of these maximum values ​​were rounded to the nearest tenth of a micrometer and then averaged to provide the thickness of the fine fiber sample.

[0793] Fiber ratio calculation based on spinning time

[0794] The relative amounts of microfibers and macrofibers (based on the total fiber count) are determined using the following equation: , Among them, D L and D S These are the diameters of the large and small fibers, respectively; and V Land V S These are the volumes of the polymers that make up the large and small fibers, respectively. Volume V is calculated based on the following for small or large fibers: , Where ρ is the density of the polymer that makes up the microfibers or macrofibers, and %w / v refers to the solid content based on the mass / volume of the polymer solution.

[0795] Fiber ratio calculation based on microscopy

[0796] Sample images are obtained via SEM at appropriate magnification (e.g., 500x, 1000x, or 2500x). The presence of one or more fiber groups is determined by counting all fibers within the image and then classifying them into fine and large fibers based on group diameters within a 25% variation. Fiber size is measured using image processing software such as ImageJ. The proportion of fine fibers is calculated by obtaining the ratio of the number of fine fibers to the total number of fibers (both fine and large fibers) within the image.

[0797] Reality

[0798] The solidity (c) of a nonwoven layer (including, for example, a non-fiber layer or a composite material comprising both a fiber layer and a non-fiber layer) is calculated using the following equation: c = BW / ρZ, where BW is the basis weight, ρ is the fiber density, and Z is the thickness of the medium.

[0799] The thickness is measured using the TAPPI T411 om-15, entitled "Thickness (caliper) of paper, paperboard, and combined board," with a foot pressure of 1.5 psi. The basis weight is measured using the TAPPI T410.

[0800] Because the thickness of the fiber layer is difficult to measure, the density of the fiber layer is calculated using an adapted version of the Kirsch-Fuchs equation based on experimentally measured pressure drop values ​​(see Kirsch et al., “Studies on Fibrous Aerosol Filters - III Diffusional Deposition of Aerosol in Fibrous Filter,” Ann. Occup. Hyg. 1968; 11:299-304). Pressure drop (ΔP or dP) is determined using a FHAST bench, as described in the Liquid Filtration Performance Testing section below.

[0801] First, the dimensionless fiber resistance parameter F* 1.0 Calculated by the following modified Kirsch-Fuchs equation: , Where BW is the basis weight, ρ is the fiber density, μ is the liquid viscosity (used for pressure drop testing), and U... ∞ It is the velocity of the liquid through the medium during the pressure drop test, and D f This is the effective fiber diameter. ΔP is determined by the FHAST stage, as described in the Liquid Filtration Performance Test section below.

[0802] Secondly, use the following equation from F* 1.0 Calculate realism (c): F* 1.0 = 4.3548e 8.8822c .

[0803] For mixed fiber media, the effective fiber diameter indicates the relative amount of small and large fibers and is calculated by the following equation: , Where r eff It is the effective fiber radius, r i Let l be the radius of fiber i, and l i This is the fraction or relative amount of fiber i. Effective fiber diameter = 2r eff .

[0804] The basis weight of one or more microfiber layers is calculated as follows: Total basis weight of microfiber layers = (mass of microfibers) / (area of ​​loose fabric).

[0805] The mass of the fine fiber is calculated as follows: Mass of fine fiber = (%w / v polymer in solution) × (pump speed) × (spinning time).

[0806] When the method for manufacturing the fine fibers is unknown, the mass of the fine fibers can be calculated as follows after separating them from the loose fabric or support (e.g., by peeling or delamination): Mass of fine fibers = (Total mass of the medium sample) - (Mass of bare loose cloth or support) Capillary flow porosity measurement (pore size measurement).

[0807] Aperture measurements were performed using a continuous pressure scan on a Porometer 3G (Quanachrome Instruments, Boynton Beach, California) via a capillary flow porosity measurement method.

[0808] Method A for measuring flow porosity

[0809] This method uses Porofil wetting solution (Quantachrome Instruments, Boynton Beach, Florida; Anton Paar) as the wetting fluid and tests samples in both wet and dry states (wet first, then dry). Samples with a diameter of 25 mm are subjected to continuous pressure scans from 0.0256 bar to 1.275 bar to determine pore sizes ranging from 1 µm to 100 µm.

[0810] Method B for measuring flow porosity

[0811] This method uses a silicone oil with a surface tension of 20.1 dynes / cm and a wetting contact angle of 0, and tests samples in both wet and dry states (dry first, then wet). Samples with a diameter of 6 mm are subjected to selected continuous pressure scans to measure most of the cumulative pore size distribution within the range of 2% to 98%.

[0812] For both methods, samples were tested from low to high pressure in both wet and dry conditions. The airflow from the test saturation section and the sample pressure are commonly referred to as the wet profile. 256 data points were collected over the pressure scan range of both the dry and wet profiles. Data points were collected throughout the scan at a rate of approximately 17 data points per minute. The test was conducted under ambient conditions (e.g., 20°C to 25°C). No empirical tortuosity factor and / or shape factor were applied to adjust the pore diameter definition.

[0813] The flow porosity measurement test procedure collects a set of pressure (typically plotted on the x-axis) and airflow (typically plotted on the y-axis) data for a dry sample, and a set of pressure and airflow data for a saturated (wet) sample. These two sets of data are commonly referred to as the dry profile and the wet profile. That is: .

[0814] Based on capillary theory, the pressure (ΔP) of the entire sample can be converted into the pore size (d) using the Young-Laplace formula. .

[0815] This conversion allows the dry and wet curves to be defined as functions of the aperture. That is: .

[0816] The cumulative flow orifice size distribution (Q) is defined as the ratio of the wet curve to the dry curve as a function of orifice size. .

[0817] The cumulative distribution can be represented as an increasing cumulative distribution from 0% to 100%, or as a decreasing cumulative distribution from 100% to 0%. The orifice size in this document is defined based on the increasing cumulative flow orifice size distribution. .

[0818] To better identify points along this curve, this document defines various P(x%) values ​​equal to the corresponding pore diameter (d). P(x%) = d, where x% = 1 - Q(d).

[0819] Examples include, but are not limited to, the following:

[0820] P5 is the pore diameter at which the incremental cumulative flow pore distribution is 5%.

[0821] P10 is the pore diameter at which the incremental cumulative flow pore distribution is 10%.

[0822] P50 is the pore diameter at which the incremental cumulative flow pore distribution is 50%.

[0823] P90 is the pore diameter at which 90% of the incremental cumulative flow pore distribution is located.

[0824] P95 is the pore diameter at which the incremental cumulative flow rate distribution is 95%.

[0825] When reporting the maximum pore size, it was determined using a Porometer 3G (Quanachrome Instruments, Boynton Beach, California) and the automatic bubble point (BP automatic tolerance) method. According to this method, the bubble point is detected after the fluid begins to flow through the sample, and increases by at least 1% after three consecutive measurements. The bubble point is the value at the beginning of this three-point sequence.

[0826] Air filtration performance

[0827] Air filtration performance was evaluated using the High Efficiency Flat Plate (HEFS) TSI Automated Filter Tester, Model 8127, test bench (TSI Incorporated, Shoreview, Minnesota). Particulate capture efficiency was measured by testing 4-inch diameter media samples with 0.3 µm oil (bis(2-ethylhexyl) sebacic acid, Sigma-Aldrich) droplets (aerosol) at a flow rate of 14.7 L / min. The TSI CertiTest 8127 Automated Filter Tester is designed to test filters, respirator cartridges, and filter media according to the latest American government and industry-wide specifications and conforms to 42 CFR § 84 (June 8, 1995).

[0828] Liquid filtration performance test

[0829] Liquid filtration performance was evaluated using a flat, high-precision, single-pass dual-fluid (FHAST) stage with the following characteristics: flow rate control: 57 mL / min to 580 mL / min, with an error of ±2%; temperature control: 25°C to 40°C, with an error of ±0.25°C; dP measurement: 0 psi to 25 psi, with an error of ±0.065%; particle size: 1.7 µm to 20 µm; maximum particle concentration: 1,000,000 / mL; dilution capacity: 5:1 to 100:1. A 2-inch diameter media sample was challenged using the FHAST stage in static mode with ISO intermediate test dust (concentration of 10 mg / L in hydraulic fluid and flow rate of 0.347 L / min) according to ISO 11171:2016. The media dP and efficiency values ​​for specific contaminant particle sizes (measured using commercially available particle counters, particularly the PAMAS 4132 liquid particle counting system, calibrated according to ISO 11171:2016 using ISO intermediate test dust calibration, Hydraulic fluid power - Calibration of automatic particle counters for liquids) were collected at fixed time intervals (approximately every 7 seconds) throughout the test duration, terminating the test when a preset maximum media dP of 20 psi was reached (measured using two test media dP sensors: (A) a differential pressure sensor with ±0.025% accuracy from 0 psi to 5 psi; a high-accuracy, low-range dP sensor, and (B) a differential pressure sensor with ±0.065% accuracy from 0 psi to 25 psi; a low-accuracy, high-range dP sensor).

[0830] The β ratio was evaluated using ISO 16889:2008 (Hydraulic fluid power — Filters — Multi-pass method for evaluating the filtration performance of a filter element) under steady flow conditions (347 mL / min through a 2-inch diameter sample). (Except when testing plate performance, this test was run in single-pass mode, not the multi-pass mode required by the standard.) The hydraulic fluid (Mobil Aero HF, MIL-PRF-5606) was loaded with 10 mg / L of ISO 12103-1 A3 intermediate test dust (Powder Technology, Inc., Ardennes, Minnesota). Instantaneous β values ​​were recorded every 7 seconds throughout the test duration. The test ended when a final dP of 20 psi was reached.

[0831] Quality Factor

[0832] The quality factor is a measure of the performance of filter media and its ability to provide a certain level of clarification of the flow with minimal energy usage. A higher quality factor value is generally better than a lower one.

[0833] The quality factor (FOM) value is calculated from the penetration fraction (P, the ratio of upstream to downstream counts), pressure drop (dP, inch H2O), and face velocity (u, fpm): FOM = (-log 10 P) / (dP / u), As described above, the penetration fraction (P), pressure drop (dP), and surface velocity (u) were measured using the HEFS TSI Automatic Filter Tester, Model 8127.

[0834] Scanning electron microscopy (SEM)

[0835] Samples are prepared for SEM imaging by sputter coating with gold. Typically, an accelerating voltage of 5 kV or 10 kV is used, and images are collected at magnifications of x500, x1000, and x2500 using a secondary electron detector or a backscattered electron detector.

[0836] Example 1

[0837] As described above, a medium is prepared using a dual-flow headbox by forming feeds of Table 1A and Table 1B and forming a medium having 55% to 60% by weight of the fibers of Table 1A (for the felt side of forming the medium) and 40% to 45% by weight of the fibers of Table 1B (for the line side of forming the medium).

[0838] The resulting properties of the medium are shown in Figure 1C. A schematic diagram of the medium is shown in... Figure 9 As shown in the image.

[0839] Table 1A - Fiber Quality Felt Side

[0840]

[0841] Table 1B - Fiber Quality Line Side

[0842]

[0843] Table 1C - Properties of the Medium

[0844] air transmittance At @125 Pa, 4.8 to 5.0 ft / min thickness 0.47 to 0.54 mm at @1.5 psi TSI8127 0.3 µm efficiency @ 10.5 ft / min 99.98%

[0845] Example 2

[0846] As described above, a medium is prepared using a dual-flow headbox by forming feeds of Tables 2A and 2B and forming a medium having 40% to 50% by weight of the fibers of Table 2A (for the felt side of forming the medium) and 50% to 60% by weight of the fibers of Table 2B (for the line side of forming the medium).

[0847] The properties obtained by the medium are in Figure 2C The schematic diagram of the medium is shown in [the diagram]. Figure 10 As shown in the image.

[0848] Table 2A - Fiber Quality Felt Side

[0849]

[0850] Table 2B - Fiber Quality Line Side

[0851]

[0852] Table 2C - Properties of the Medium

[0853] air transmittance <![CDATA[20 to 23 ft 3 / ft 2 / min @ 125Pa]]> thickness 0.40 mm to 0.42 mm at @ 1.5 psi TSI8127 0.3 µm efficiency @ 10.5 ft / min 95.3%

[0854] Example 3

[0855] The media in Example 1 was pleated to 8 pleats per inch using a knife-type pleating machine. A schematic diagram of the resulting media is shown in [image / description]. Figure 11 As shown in the image.

[0856] Table 3

[0857]

[0858] Example 4

[0859] As described in Example 3, the medium in Example 1 is pleated and incorporated into the filter element. The resulting filter element was tested. The results are shown in Table 3 and... Figure 15 As shown in the image.

[0860] - Excellent pressure drop was observed even at flow rates higher than typical (typical flow rate was 3 cfm; filter element was tested at 8 cfm). A pressure drop of 0.21 was observed.

[0861] Example 5

[0862] Geodict (Math2Market) was used to simulate a glass-free filter medium comprising 40 wt% of 14 µm diameter bicomponent fibers, 20 wt% of 0.7 µm diameter PET fibers, 20 wt% of 2.5 µm diameter PET fibers, and 20 wt% of 1 µm diameter fibrillated rayon fibers. The resulting medium is graphically represented in... Figure 16 As shown in the image.

[0863] Example 6

[0864] By 24 g / m 2 A blend of 14 µm diameter bicomponent fibers (Advansa 271P) and varying amounts of 700 nm diameter PET fibers (TJ04BN, Teijin Fibers Limited, Osaka, Japan) Figure 17 (circle) or by using 24 g / m 2 14 µm diameter bicomponent fibers with varying amounts of 700 nm diameter PET fibers, 1 µm diameter fibrillated rayon fibers (lyocell fibers), and 2.5 µm diameter PET fibers (Osaka Teijin Fibers Co., Ltd., Japan) Figure 17 (Square) mixtures were used to prepare hand-coated sheets in a wet web-forming process, and β was measured to determine β. 4 µm = 10,000. The result is in Figure 17 As shown in Table 4, different amounts of 700 nm diameter PET fibers were used to provide different basis weights. The amount of each fiber added is shown in Table 4.

[0865] Table 4

[0866]

[0867] Based on the collected data, it is estimated that the content of 24 g / m 2Achieving β in a medium with 14 µm diameter bicomponent fibers 4 µm = 10,000 will require approximately 20g / m³ 2 The 700 nm diameter PET fibers. However, when adding 1 µm diameter fibrillated rayon fiber and 2.5 µm diameter PET fiber to 700 nm diameter PET fibers and 14 µm diameter bicomponent fibers, only about 12 g / m² is needed. 2 700 nm diameter PET fibers to achieve β 4 µm = 10,000.

[0868] These results are unexpected, as smaller fibers are typically added to create efficient media for liquid filtration. However, as this example shows, the same efficiency achieved by adding 700 nm diameter PET fibers to a 14 µm diameter bicomponent fiber is achieved by removing some of these smaller fibers and replacing them with larger fibrillated rayon fibers (1 µm (1000 nm) diameter) and PET fibers (2.5 µm (2500 nm) diameter).

[0869] Without being bound by theory, it is believed that combining 1 µm diameter fibrillated rayon fibers with 2.5 µm diameter PET fibers is particularly beneficial. The 1 µm diameter fibrillated rayon fibers are believed to provide higher tensile strength compared to using 2.5 µm diameter PET fibers without fibrillated rayon fibers. The 2.5 µm diameter PET fibers are believed to provide a more uniform pore structure compared to using fibrillated rayon fibers without 2.5 µm diameter PET fibers.

[0870] Example 7

[0871] For Captimax 190 SC (Ahlstrom) Figure 18 "Base layer") and for polyester meltblown (FF40 / 240PBT, Ahlstrom) and Captimax 190 SC (Ahlstrom) Figure 18 The combination of "polyester meltblown on the base layer" was used to measure β using ISO fine test dust at a concentration of 40 mg / L. 4 µm .

[0872] Hand-made sheets were prepared in a wet web-forming process by mixing 50 wt% of 14 µm diameter bicomponent fibers with 1 µm diameter fibrillated rayon fibers (lyocell fibers) and 2.6 µm diameter PET fibers (TJ04BN, Teijin). Figure 18 "DCI without glass on the base layer"); β was measured using ISO fine test dust at a concentration of 40 mg / L. 4 µmThe result was... Figure 18 As shown in the image.

[0873] When measuring the β of Captimax medium 4 µm Different efficiencies were observed at different times. Not wanting to be bound by theory, this could be due to a lack of uniform pore size. The presence of larger pores leads to a decrease in efficiency observed when adding larger particles, until those larger particles fill the larger pores, at which point the efficiency increases again.

[0874] Example 8

[0875] This example illustrates the increased efficiency and lifespan achieved by using composite materials that include a layer of fine fibers.

[0876] Preparation of the plate includes applying a loosely woven cloth (1 oz / yd) 2 Polyester (sold under the trade name Reemay) and Synteq® 10XP (Donaldson Ltd., Minneapolis, Minnesota) are coated on a loosely woven fabric. Figure 20A (left image), or use 1 µm diameter fine fibers electrospun to form a layer on it and then cover the fine fiber layer with Synteq® 10XP ( Figure 20A (Right side diagram).

[0877] like Figure 19A As shown, adding a microfiber layer increases the load-bearing capacity (i.e., lifespan) of the plate compared to a plate without a microfiber layer. Figure 10 As shown in Figure B, adding a fiber layer increases the efficiency of the plate compared to a plate without a fiber layer.

[0878] These results were unexpected, as it had been previously reported that forming interfaces between dielectric layers was undesirable, and that gradient structures should be used instead. (See, for example, US Publication No. 2014 / 0360145.)

[0879] Not wanting to be bound by theory, it is believed that forming interfaces between dielectric layers can allow for higher efficiency because the non-uniformity of each layer is misaligned throughout the dielectric depth.

[0880] Example 9

[0881] The fabric comprises a sheet consisting of a loosely woven fabric, a 700 nm diameter PET fiber layer, and a mixture of 40% to 60% bicomponent fibers with a diameter of 14 µm, 0% to 25% PET fibers with a diameter of 2.5 µm, and 10% to 40% fibrillated rayon fibers with a diameter of 1 µm, as described in Example 6 or Example 7. Figure 20B The same increase in load capacity and efficiency is expected in the handwritten sheet as reported in Example 4.

[0882] To avoid being bound by theory, it is believed that the 700 nm diameter PET fiber layer will act as the efficiency layer, and the hand-copied sheet will act as the load layer. It is anticipated that the variable efficiency that would have been observed when using the hand-copied sheet alone will be eliminated by combining it with the 700 nm diameter PET fiber (which acts as the efficiency layer).

[0883] Example 10

[0884] The XP / fiber / sparse fabric medium is constructed by combining the following components: a Synteq XP™ synthetic liquid medium with a 10-micron efficiency rating (Donaldson Ltd., Minneapolis, Minnesota) as the efficiency layer, a support layer (CEREX 23200, Cyrex Advanced Fabrics, Candenmen, Florida), and a continuous fiber layer deposited on the support layer using electrospinning. The continuous fiber layer is formed from SVP 651 (see Table 7). The efficiency layer is the upstream layer; the continuous fiber layer is placed downstream of the efficiency layer; and the support layer (sparse fabric) is placed downstream of the continuous fiber layer.

[0885] These layers are placed on top of each other and housed within the filter housing.

[0886] Although the Synteq XP™ synthetic liquid media and XP / fine fiber / sparse cloth media, both with a 5-micron efficiency rating, were observed to have comparable efficiencies, the XP / fine fiber / sparse cloth media exhibited improved pressure drop, such as... Figure 23 As shown in the image.

[0887] Table 7

[0888]

[0889] Example 11

[0890] The media were prepared according to the following methods: Method 3 of the suspended drop sample preparation, Table 5 Group A (small fine fibers directly deposited on loose cloth) and Method 4 of the suspended drop sample preparation, Table 5 Group A (small fine fibers deposited on a layer of large fine fibers deposited on loose cloth).

[0891] An exemplary image of a large microfiber layer deposited on a loosely woven fabric. Figure 22B As shown in the image.

[0892] An exemplary image of fine fibers directly deposited on a loosely woven fabric. Figure 22C An exemplary image shown in the figure illustrates the deposition of fine fibers on a layer of large fibers deposited on a loosely woven fabric. Figure 22D (Small fibers deposited on a layer of large fibers deposited on a loosely woven fabric) is shown in the figure.

[0893] Example 12

[0894] The medium was prepared according to method 1 for preparing hanging drop samples. The resulting nonwoven fabric had a density of 1.64 g / m³. 2 The theoretical foundation.

[0895] The control nonwoven media prepared by co-spinning each single electrospinning precursor solution from two different syringes had a concentration of 0.56 g / m³ for solutions 1 and 2, respectively. 2 Or 1.08 g / m 2 The theoretical foundation.

[0896] The obtained SEM image of the medium in Figure 22E As shown in the image.

[0897] Example 13

[0898] This example describes a filter media comprising a support layer (Cerex 23200) and a continuous layer of fine fibers formed from a nylon copolymer resin dissolved in alcohol (ethanol, 190 degrees Celsius) (SVP 651, obtained from Shakespeare Co., Columbia, South Carolina, a terpolymer containing 45% nylon-6, 20% nylon-6,6 and 25% nylon-6,10 with a number-average molecular weight of 21,500 to 24,800). The nylon copolymer resin is heated to 60°C to produce a 9% (w / w) nylon solid solution (Example 13A) or an 11% (w / w) nylon solid solution (Example 13B). The solution is stirred until homogeneous and then electrospinned.

[0899] In Example 13A, the continuous fine fiber layer comprises fine fibers with an average diameter of 200 nm to 300 nm. Exemplary SEM images are shown in... Figure 24A As shown in the figure, the filter media exhibits an efficiency of >95% at 0.3 µm and a pressure drop (dP) < 29 mmH2O.

[0900] In Example 4B, the continuous fine fiber layer comprises fine fibers with an average diameter of 350 nm to 450 nm. Exemplary SEM images are shown in... Figure 24B As shown in the figure, the filter media exhibits an efficiency of >95% at 0.3 µm and dP < 29 mm H2O.

[0901] Table 8 provides a comparison of the properties of the media in Examples 13A and 13B.

[0902] Table 8

[0903] Cerex 23200 (naked loose cloth) 65.1 ± 15.6 48.5 ± 10.0 23.6 ± 11.7 Fibers with diameters ranging from 200 nm to 300 nm (Example 13A) 8.3 ± 5.8 2.2 ± 0.2 2.1 ± 0.2 Fibers with diameters ranging from 350 nm to 450 nm (Example 13B) 2.9 ± 0.1 2.3 ± 0.1 2.15 ± 0.05

[0904] Example 14

[0905] Large and small fibers can be deposited to form multiple (e.g., > 3) layers with various arrangements of single fiber diameter and / or mixed fiber diameter. Figure 25 The figure shows the performance metrics (quality factor, which takes into account both efficiency and pressure drop) for the pressure drop across the 0.3 µm contaminant particles and the air filter media.

[0906] Example 15

[0907] The sample integrity of the composite samples was evaluated during FHAST stage testing at up to 20 psi (at a face wind speed of 0.56 ft / min, as further described in the Liquid Filtration Performance Test Methods), and the initial pressure drop of each composite was plotted against the maximum pore size of the composite. As used in this example, "composite" refers to any fiber layer (including, for example, a first fiber layer, a second fiber layer, etc.) and a support layer. The composite includes at least one fiber layer.

[0908] According to flow porosity measurement method A, the average maximum pore size (P100) and average flow pore size (P50) of the composite material for each sample are measured by flow porosity measurement technique.

[0909] Each sample comprises fine fibers of mixed diameters and a substrate. Some samples comprise a layer of fine fibers, which includes “large” and “small” fine fibers, prepared as described in method 1, 2, or 3. Some samples comprise a first continuous layer of fine fibers and a second continuous layer of fine fibers, wherein the first continuous layer comprises fine fibers whose average diameter is at least three times the average fiber diameter of the smallest fiber in the second continuous layer of fine fibers, prepared as described in method 4, 5, 6, or 7.

[0910] The results are shown in Figure 26. Triangles represent samples that maintained the integrity of the fine fiber structure throughout the FHAST stage test; squares represent samples that suffered fine fiber bursting during the FHAST stage test (indicated by β reduction). Samples comprising two layers of fine fibers (the first layer consisting of fine fibers with an average diameter at least three times the average fiber diameter of the smallest fiber in the second layer) are indicated by the filled shape. Samples containing a single layer of fine fibers comprising fibers of mixed diameters are indicated by the unfilled shape.

[0911] Most media samples with only one layer of fine fibers (i.e., those prepared using methods 1, 2 or 3) exhibit fine fiber damage (represented by hollow cubes).

[0912] During the FHAST stage test layers (represented by hollow triangles), some media samples with only one layer of fine fibers survived at a maximum of 20 psi. Not wanting to be bound by theory, it is believed that these fiber layers withstood the test due to their very high coverage (basis weight)—but such a high basis weight comes at the cost of a high initial pressure drop.

[0913] In contrast, all media samples prepared using methods 4, 5, 6, or 7 and including two fine fiber layers maintained the integrity of the fine fiber structure (represented by solid triangles).

[0914] The results show that the average maximum pore size of the composite material ( Figure 26A ) and average flow pore size of composite materials ( Figure 6 B) Both are related to the ability of the composite material to withstand the FHAST bench test—a laboratory test that is highly correlated with the composite material’s ability to withstand a pressure drop of at least 20 psi during liquid filtration—indicating that the filtration performance is superior to that of filter media that cannot withstand the same conditions.

[0915] While some media samples with an average maximum pore size (P100) of up to 20 µm withstood the FHAST test, a transition zone was observed for media samples with an average maximum pore size between 14 µm and 20 µm, where some media samples began to fail the test.

[0916] Similarly, while some media with an average flow pore size (P50) of up to 11 µm withstood the FHAST test, a transition zone was observed for media samples with an average maximum pore size between 6 µm and 11 µm, where some media samples began to fail the test.

[0917] For example, a composite material sample with an average maximum pore size of 11 µm without large fine fiber supports cannot pass the FHAST stage test, while a composite material sample with an average maximum pore size of 11 µm and large fine fiber supports can pass the FHAST stage test. The ability to use fine fiber samples with larger pore sizes allows for fine-tuning of efficiency without causing adverse pressure drops in the resulting composite.

[0918] Example 16

[0919] Composite materials comprising a fine fiber layer and a support layer are prepared according to pendant drop sample preparation methods 8A to 8C to form fine fiber sample A, fine fiber sample B and fine fiber sample C (each of these fine fiber samples also includes a support layer, as described above).

[0920] The efficiency layer is prepared as described in the section on the preparation of the media hand-copied sheet. The efficiency layer comprises 40 wt-% glass fiber (Lauscha B-10-F, nominal fiber diameter of 1 µm, Lauscha Fiber International (Lauscha, Germany)) and 60 wt-% bicomponent fiber (Teijin TJ04CN, Teijin Limited (Tokyo, Japan)) to form efficiency layer A.

[0921] Capillary flow porosity measurements were performed on fine fiber sample A, fine fiber sample B, fine fiber sample C, and efficiency layer A according to flow porosity measurement method B. The results are shown in Table 9 and... Figure 27 As shown in the image.

[0922] Table 9.

[0923] Efficiency Layer A 17.81 µm 15.73 µm 8.82 µm 5.40 µm 4.70 µm 2.02 µm 3.30 µm Fine fiber sample A 8.59 µm 7.69 µm 5.07 µm 3.89 µm 3.62 µm 1.70 µm 2.21 µm Fine fiber sample B 5.85 µm 5.54 µm 3.48 µm 2.29 µm 2.12 µm 1.68 µm 2.55 µm Fine fiber sample C 4.39 µm 4.06 µm 2.88 µm 1.70 µm 1.45 µm 1.52 µm 2.58 µm

[0924] The medium is prepared as described in the section on the preparation of the medium hand-copied sheet. The medium comprises 40 wt-% glass fiber (Lauscha B-26-R, nominal fiber diameter 2.4 µm, Lauscha Fiber International (Lauscha, Germany)) and 60 wt-% bicomponent fiber (Teijin TJ04CN, Teijin Limited (Tokyo, Japan)) to form the load layer A.

[0925] The performance of the filter media, including both the load layer A and the efficiency layer A, was evaluated under both steady-flow and circulating flow conditions. The results are shown in Table 10A. As can be seen from the results in Table 10A, although the load layer and efficiency layer exhibit good performance under steady-flow conditions (as indicated by the low pressure drop (ΔP)) and high efficiency under circulating flow conditions without the fine fiber layer, the efficiency drops sharply. While the media can efficiently filter particles with a diameter of 10 µm under steady-flow conditions, the efficiency for particles of the same diameter is more than 50 times lower under circulating flow conditions. Similarly, while the media can filter 99% of particles with a diameter of 9.3 µm under steady-flow conditions, the same 99% filtration cannot be achieved under circulating flow conditions unless the particle diameter is 27 µm.

[0926] As shown in Table 10B, the addition of certain fiber layers (fiber sample A, fiber sample B) can "rescue" this efficiency loss while maintaining an acceptable voltage drop. In contrast, the addition of fiber sample C results in an undesirably high voltage drop (three times larger than that exhibited by the load layer A and efficiency layer A alone). The porosity of fiber sample C is smaller than that of efficiency layer A, therefore the P95 of fiber sample C (4.39 µm) does not fall within the P5 to P50 range (4.70 µm to 8.82 µm) of efficiency layer A. In contrast, both fiber samples A and B have a P95 that falls within the P5 to P50 range (4.70 µm to 8.82 µm) of efficiency layer A.

[0927] Having very small pore sizes in the fiber layer (as in, for example, the fiber sample C) leads to an increased pressure drop because the fibers impede airflow through the filter medium. Furthermore, it is undesirable to be bound by theory; it is believed that having pore sizes in the fiber layer much smaller than those in the efficiency layer also results in lower efficiency because the fiber layer traps particles of a size that the efficiency layer cannot capture. Conversely, when the pore sizes of the fiber layer and the efficiency layer overlap, particles of a size that are trapped in the fiber layer may also be trapped in the efficiency layer.

[0928] Table 10A.

[0929] steady flow Load layer A / Efficiency layer A 7.6 kPa 152 9.3 µm Circulation Load layer A / Efficiency layer A 7.2 kPa 2.39 27 µm

[0930] Table 10B

[0931] Circulation Load layer A / Efficiency layer A / Fine fiber sample A 10.3 kPa 8.53 17 µm Circulation Load layer A / Efficiency layer A / Fine fiber sample B 15.8 kPa 129 9.5 µm Circulation Load layer A / Efficiency layer A / Fine fiber sample C 23.2 kPa 2470 4.1 µm

[0932] Example 17

[0933] The sample prepared according to method 9 was analyzed using the "fine fiber layer thickness" method. Exemplary images are shown in... Figure 28A As shown, the entire depth of the fine fiber layer is visible in the cross-section, and the fibers of the support layer are visible in the bottom portion of the image.

[0934] Figure 28B The diagram shows how to depict a fine fiber cross-section using a polygon tool. Figure 28C The image shows the area outside the selected fine fiber section after it has been cleared. Figure 28D The image shows the selected area of ​​the fine fiber section after it was recolored white using a threshold level tool (to compensate for the fibers at the boundaries of the selected section), and the dashed line indicates the maximum thickness measured and recorded in the image (5.97 µm). Five of these maximum values ​​were rounded to the nearest tenth of a micrometer, and then these rounded values ​​were averaged. The results are shown in Table 11.

[0935] Table 11

[0936] Sample 1 5.97 6 Sample 2 8.17 8.2 Sample 3 7.203 7.2 Sample 4 6.941 6.9 Sample 5 4.702 4.7 Average thickness of the fine fiber layer 6.6

[0937] All disclosures of patents, patent applications, publications, and materials available electronically herein are incorporated herein by reference. In the event of any inconsistency between the disclosures of this application and those of any other document incorporated herein by reference, the disclosures of this application shall prevail. The detailed descriptions and examples above are provided for clarity only and should not be construed as unnecessary limitations. The invention is not limited to the precise details shown and described, and variations that will be apparent to those skilled in the art will be included within the scope of the invention as defined by the claims.

Claims

1. A filter medium comprising a fiber layer, the fiber layer comprising: Microfibrillated cellulose fibers, wherein the microfibrillated cellulose fibers have an average diameter; Glass fibers having an average diameter, wherein the glass fibers form a gradient from a high concentration at one main surface of the fiber layer to few or no glass fibers at the other main surface of the fiber layer; Multicomponent adhesive fibers, the multicomponent adhesive fibers having an average fiber diameter; and Additional fibers, wherein the average diameter of the additional fibers is between the average diameter of the glass fibers and the average fiber diameter of the multicomponent adhesive fibers, or between the average diameter of the microfibrillated cellulose fibers and the average fiber diameter of the multicomponent adhesive fibers.

2. The filter medium according to claim 1 further includes a fine fiber layer, wherein the fine fiber layer is directly deposited on the fiber layer by electrospinning.

3. A face mask system, comprising: A face mask, the face mask being defined as a facial container configured to receive the wearer's nose and mouth; A retaining feature, the retaining feature being configured to retain the position of the mask relative to the wearer; An air intake airflow path extends from the surrounding environment to the face container; and A filter element is disposed across the intake airflow path, wherein the filter element includes the filter medium as described in claim 1.

4. The mask system of claim 3, wherein, The filter element includes one or more folds formed therein.

5. The mask system of claim 3 or 4, wherein, The retaining feature includes straps.

6. The mask system according to any one of claims 3 to 4, wherein, The retaining feature includes a headband.

7. The mask system according to any one of claims 3 to 4, wherein, The face mask includes the filter element.

8. The mask system according to any one of claims 3 to 4, wherein, The filter element is located away from the face mask.

9. The mask system according to any one of claims 3 to 4, wherein, The face mask is made of an airtight material defining an opening, wherein the filter element is positioned above the opening, and the face mask system further includes: An exhalation valve that defines an exhaust airflow path from the face container to the surrounding environment.

10. The mask system according to any one of claims 3 to 4, in, The mask system includes a filtering face mask respirator, and The filter element forms at least a portion of the mask of the filter-type face mask respirator.

11. The mask system according to any one of claims 3 to 4, wherein, The mask system includes surgical masks.

12. The mask system according to any one of claims 3 to 4, wherein, The mask system includes a powered air-purifying respirator, the powered air-purifying respirator including an airflow duct extending into the mask, wherein the airflow duct defines a portion of the intake airflow path.

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