Porous membranes for filter media

Abstract

Porous membranes comprising short or discrete fibers and nanoparticles dispersed throughout at least a portion of the membrane and methods of making such porous membranes are provided. The filter media comprises a porous membrane comprising staple fibers and having an average pore size of less than about 10 microns. The media also includes nanoparticles disposed within the porous membrane. The nanoparticles reduce the average pore size of the membrane while substantially maintaining the pressure drop (e.g., bubble point) across the membrane. The porous membranes may be configured for use as filter media and are particularly useful for gas or liquid filters, including but not limited to membrane filters, diesel filters, air filters, masks, gas turbine and compressor intake filters, plate filters, cartridge filters, bag filters, cleaning in situ (CIP) filters, and the like.

Description

Cross-references to related applications

[0001] This application claims the benefit of U.S. Provisional Application Serial No. 63 / 517,656, filed August 4, 2023, the entire disclosure of which is incorporated herein by reference for all purposes. Technical Field

[0002] This specification generally relates to filter media for gas or liquid filters, and more specifically to porous membranes for such filters, comprising fibers and nanoparticles or chopped fibers incorporated into the porous membrane. Background Technology

[0003] Porous membranes are widely used in a variety of applications, depending on their properties, such as the materials used to prepare the membranes, their morphology, and the size of the pores. For example, these membranes can be used as filter media, separation membranes, membrane adsorbers, and membrane catalysts.

[0004] One specific application of porous membranes is liquid filtration. Liquid filtration is the process of removing solid particles, impurities, and contaminants suspended in a fluid flow. It typically involves passing a process liquid (in the form of a slurry or suspension) through a permeable filter medium, and blocking and trapping the captured solids.

[0005] There are two main types of liquid filtration: surface and depth filtration. The main difference between the filtration methods lies in the structure of their filter media. In surface filtration, particle sieving occurs on the surface of the filter media. There are gaps between the fibers of the filter media called pores. Particles with a diameter larger than the pore width are blocked on the upstream side of the filter media and form a filter cake. Particles with a diameter smaller than the pore width are allowed to pass through the filter media. At the start of the filtration process, the filter efficiency is approximately 50-60%. As the filter cake accumulates, the filtration efficiency increases to up to 100% because the filter cake also provides resistance to particle flow.

[0006] Surface filters are economical for liquid filtration. However, this type of filter has a lower particle holding capacity and is more prone to clogging. They also require more frequent replacement, although they can be reused after cleaning.

[0007] Depth filtration is used to trap particles throughout the entire depth of the filter media. Depth filters typically use thick, multi-layered filter media, which increases their density in the direction of flow. Larger particles are trapped on the filter surface where the media density is lowest, while the particle size gradually decreases throughout the filter's depth. The high pore volume of the filter provides a tortuous and difficult flow path for solids. The significant resistance it provides effectively prevents solid particles from binding into the filtrate.

[0008] Depth filters are typically used when process fluids contain a wide range of particle sizes. Depth filters can filter particles smaller than the average pore size, and they have a higher particle holding capacity, trapping large amounts of solids before they become clogged. They can remove gel-like particles from process fluids. Finally, they have a long service life and require less frequent replacement, but they are generally single-use products.

[0009] When determining the required flow rate, key considerations are pore size and the desired liquid flux. The membrane pore size is selected based on the expected performance of the final device. Porosity determines the membrane's functional properties, including flow rate and flux. For example, using membranes with smaller pore sizes generally increases the filter's efficiency in capturing contaminants. On the other hand, these smaller pore sizes typically result in lower flow rates and reduced flux compared to membranes with larger pore sizes. Summary of the Invention

[0010] To provide a basic understanding of some aspects of the claimed subject matter, a simplified overview is presented below. This overview is not an exhaustive summary of the claimed subject matter. It is neither intended to identify the key elements of the claimed subject matter nor to define its scope. Its sole purpose is to present some ideas of the claimed subject matter in a simplified form as a prelude to a more detailed description that follows.

[0011] Various embodiments provide porous membranes comprising short or discrete fibers and nanoparticles dispersed throughout at least a portion of the membrane, as well as methods for preparing such porous membranes. These porous membranes can be configured for use as filter media and are particularly suitable for gas or liquid filters, including but not limited to filter presses, membrane bioreactor membranes, hydrocarbon filters, diesel filters, fluid filters, beverage filters, microfiltration membranes, downstream membrane filtration, air filters, face masks, gas turbine and compressor inlet filters, plate filters, cartridge filters, bag filters, clean-in-situ (CIP) filters, battery separators, etc.

[0012] In one aspect, the filter medium comprises a porous membrane with an average flow pore size of less than about 10 micrometers. This membrane comprises short fibers and nanoparticles disposed within the porous membrane. The nanoparticles reduce the average pore size of the membrane while substantially maintaining the flow rate and / or pressure drop through the membrane.

[0013] In the implementation scheme, the average flow pore size of the membrane is less than 5 micrometers, preferably less than 4 micrometers, more preferably less than 3 micrometers, and more preferably less than 1 micrometer.

[0014] In this embodiment, the short fibers are formed from a wet-laid medium containing chopped fibers and can be produced by any conventional method. The short fibers can have any suitable length, for example, from about 2 mm to about 80 mm.

[0015] The fibers can be man-made or natural. Suitable materials for fibers include, but are not limited to, polyester, polypropylene (PET), PEN polyester, PCT polyester, polypropylene, PBT polyester, copolyamide, polyethylene, high-density polyethylene (“HDPE”), LLDPE, cross-linked polyethylene, polycarbonate, polyacrylate, polyacrylonitrile, polyfuran, polystyrene, styrene-maleic anhydride, polymethylpentene, cyclic olefin copolymers or fluorinated polymers, polytetrafluoroethylene, perfluoroethylene and hexafluoropropylene or copolymers with PVDF (such as P(VDF-TrFE)) or terpolymers (such as P(VDF-TrFE-... CFE), propylene, polyimide, polyetherketone, cellulose esters, nylon and polyamide, polymethacrylic acid, poly(methyl methacrylate), polyoxymethylene, polysulfonate, acrylic acid, styrene-acrylic acid, pre-oxidized acrylic acid, fluorinated acrylic acid, vinyl acetate, vinyl acrylic acid, ethylene vinyl acetate, styrene-butadiene, ethylene / vinyl chloride, vinyl acetate copolymer, latex, polyester copolymer, carboxylated styrene acrylic acid or vinyl acetate, epoxy resin, acrylic multi-polymer, phenolic resin, polyurethane, cellulose, styrene, PVOH, PVA or any combination thereof. Other conventional fiber materials are also considered.

[0016] In some embodiments, the short fibers comprise polyolefins, polyesters, polyethylene (PE), polypropylene (PP), blends of PP and PE, PBT, PET, CoPET, PLA, PA, PHB, PVOH, PVA polyamide, and combinations thereof. In a preferred embodiment, the fibers comprise polyester.

[0017] The cross-section of the fiber under consideration can have many shapes, including but not limited to circular, bean-shaped, dogbone-shaped, trefoil-shaped, barbell-shaped, bowtie-shaped, star-shaped, Y-shaped, etc., with a range of fibers of different deniers within each section. The fiber can include biological component fibers, comprising two or more different fibers bonded together. The fiber can contain the same or different materials. The fiber can include biological component fibers having a core and a sheath. The core can be concentric or non-concentric with respect to the longitudinal axis of the sheath.

[0018] In some embodiments, the nanoparticles are dispersed "at a certain depth" within the porous membrane. As used herein, the term "at a certain depth" means that the nanoparticles are dispersed across a first surface of the membrane such that at least some nanoparticles are disposed between the first and second opposing surfaces within the internal structure of the membrane. In some embodiments, the nanoparticles are substantially dispersed throughout the entire membrane from the first surface to the opposing second surface. In other embodiments, the nanoparticles are dispersed within a portion of the membrane at a location between the first and second surfaces.

[0019] In some implementations, the nanoparticles are three-dimensionally distributed in space relative to the supporting fibers, which can increase the fiber surface area and the microvolume within the membrane. This three-dimensional distribution also prevents complete clogging of specific sections of the porous membrane, which is particularly useful in filter media as it allows liquids or gases to pass through the filter, thereby reducing the overall pressure drop across the filter.

[0020] Nanoparticles can be disposed on the first and second opposing surfaces of the membrane such that the areal density of the nanoparticles decreases from the first surface to the second surface, or that the areal density of the nanoparticles disposed on both surfaces is higher compared to the middle portion of the membrane. The density gradient formed by the nanoparticles within at least a portion of the membrane improves the performance characteristics of the filter. For example, the nanoparticles reduce the porosity of the membrane, which can increase its filtration efficiency, thereby allowing contaminants to be captured without significantly impairing other factors, such as the pressure drop across the filter (i.e., flow rate).

[0021] In some embodiments, the density of nanoparticles located on the first surface differs from the density of nanoparticles dispersed in the central portion or midpoint between the two surfaces of the substrate by less than 50%. In some embodiments, this difference is less than 25%, preferably less than 10%. In some embodiments, the amount or number of individual nanoparticles dispersed in the central portion of the film is at least about 50% of the amount of individual nanoparticles dispersed on or near the first surface, preferably at least about 75%, more preferably at least about 90%.

[0022] In some embodiments, nanoparticles can be added to the film from both the first and second surfaces. In these embodiments, the areal density, or "addition amount," at the first and second surfaces can be substantially equal to each other, or they can vary depending on the application. In these embodiments, the areal density, or "addition amount," present in the middle of the substrate is lower than that at the outer surface. For example, the areal density in the middle of the substrate can be about 75% of the areal density at the outer surface, or it can be about 50%, 40%, or 25%.

[0023] In some embodiments, the nanoparticles are isolated within a fluid and dispersed through a first surface of the substrate. The fluid may be a gaseous medium, such as air, helium, nitrogen, oxygen, carbon dioxide, etc. The nanoparticles may be dispersed from the gaseous medium via an airflow, aerosol, vaporizer, spray, or other suitable delivery mechanism.

[0024] Nanoparticles can include any suitable material, such as glass, biosoluble glass, fibrillated cellulose, ceramic materials, acrylic acid, carbon, metals (e.g., alumina), polymers (e.g., nylon, polyethylene terephthalate, etc.), polyvinyl chloride (PVC), polyolefins, polypropylene, polyacetal, polyester, cellulose ether, polyalkylene sulfide, poly(aryloxide), polysulfone, modified polysulfone polymers, and polyvinyl alcohol, polyamide, polystyrene, polyacrylonitrile, polyvinylidene chloride, polymethyl methacrylate, polyvinylidene fluoride, and any combination thereof.

[0025] In another aspect, the liquid filter comprises a porous membrane containing fibers and having an average flow pore size of less than about 10 micrometers. The filter has a bubble point (i.e., the maximum measurable pore size of the filter) of about 5 to about 50 micrometers, preferably less than about 30 micrometers, or less than about 20 micrometers, or less than about 10 micrometers, or about 5 micrometers.

[0026] In the embodiments, the average pore size of the membrane is less than 5 micrometers, preferably less than 4 micrometers, more preferably about 3 micrometers, and more preferably less than 1 micrometer.

[0027] In this embodiment, the short fibers are wet-laid fibers and can be produced by any conventional method. The short fibers can have any suitable length, for example, from about 2 mm to about 80 mm.

[0028] Liquid filters can include, for example, clean-in-place (CIP) filters, bag filters, and cartridge filters. Such cartridge filters can include, for example, pleated cartridges, spunbond cartridges, activated carbon cartridges, reverse osmosis membrane cartridges, alkaline cartridges, and ultraviolet cartridges.

[0029] On the other hand, a method of manufacturing a filter medium includes providing a porous membrane comprising fibers and dispersing nanoparticles onto a first surface of the porous membrane such that the nanoparticles penetrate at least the first surface of the membrane.

[0030] In an embodiment, the method further includes calendering short fibers and nanoparticles to reduce the average pore size of the porous membrane to less than about 10 micrometers, preferably less than about 5 micrometers, and more preferably less than about 3 micrometers.

[0031] In the implementation plan, the fiber is a short fiber processed by a wet web forming process.

[0032] In some embodiments, the nanoparticles are isolated within a fluid and dispersed through a first surface of a porous membrane. The fluid may be a gaseous medium, such as air, helium, nitrogen, oxygen, carbon dioxide, etc. The nanoparticles may be dispersed from the gaseous medium via an airflow, aerosol, vaporizer, spray, or other suitable delivery mechanism.

[0033] In one embodiment, the method further includes advancing a porous membrane from an upstream end to a downstream end, and introducing a nanofiber assembly into a fluid medium. The nanofiber assembly is converted into nanoparticles within the fluid medium and then dispersed into the porous membrane between the upstream and downstream ends to form a fibrous material.

[0034] The method may also include applying an adhesive to fibers within a porous membrane. The adhesive may be sprayed onto the membrane, for example, before and / or after the nanoparticles are dispersed in the membrane. The adhesive inhibits the direct passage of nanoparticles through the membrane, and when the nanoparticles are bound to the adhesive, it can increase the uniformity and permeability of the nanoparticles within the membrane's internal structure.

[0035] The description of the desired objectives fulfilled by the various embodiments herein is not intended to imply or suggest that any one or all of these objectives are necessary features, either alone or collectively, present in the most generalized embodiments of this specification or in any of its more specific embodiments. Attached Figure Description

[0036] Figure 1 It is a side view of a porous membrane with nanoparticles dispersed in a portion of the material; Figure 2 It is a side view of a porous membrane with nanoparticles dispersed throughout the material; Figure 3 It is a side view of a porous membrane with nanoparticles dispersed in the material in a gradient. Figure 4 It is a side view of a dual-layer filter with nanoparticles dispersed in the material in a gradient. Figures 5A-5C Representative bio-component fibers are shown for inclusion in porous membranes; Figure 6 A liquid cartridge filter is shown; Figure 7 A liquid bag filter is shown; Figure 8 A system for fabricating porous membranes containing nanoparticles is illustrated schematically. Figure 9 A system for converting nanofiber clusters into individual nanoparticles is illustrated schematically. Figure 10-12 These are photographs of large nanofiber clusters, smaller nanofiber clusters, and individualized nanoparticles.

[0037] Figure 13 It shows Figure 8 The system's injectors; Figure 14 It shows Figure 8 The system's reactor; Figure 15Another embodiment of a system for converting nanofiber clusters into single nanoparticles is shown; Figure 16 A porous membrane with nanoparticles dispersed to a certain depth within the material is shown; Figure 17 A porous membrane with nanoparticles dispersed to a certain depth in the material and a loosely woven layer covering the nanoparticles is shown. Figure 18 A bilayer porous membrane with nanoparticles dispersed on the inner surfaces of two layers is shown; and Figures 19A-19C These are microscopic images of HDPE nanoparticles dispersed on the combing medium. Detailed Implementation

[0038] This specification and accompanying drawings illustrate exemplary embodiments and should not be construed as limiting. The scope of this specification is defined by the claims, including equivalents. Various mechanical, compositional, structural, and operational changes may be made without departing from the scope of this specification and the claims (including equivalents). In some cases, well-known structures and techniques have not been shown or described in detail to avoid obscurity. Identical numbers in two or more figures represent identical or similar elements. Furthermore, whenever practicable, elements and related aspects described in detail with reference to one embodiment may be included in other embodiments where they are not specifically shown or described. For example, if an element is described in detail with reference to one embodiment but not with reference to a second embodiment, that element may still be claimed to be included in the second embodiment. Moreover, the descriptions herein are for illustrative purposes only and do not necessarily reflect the actual shape, size, or dimensions of the system or illustrated components.

[0039] It should be noted that, as used in this specification and the appended claims, the singular forms “a,” “an,” and “the,” and any singular use of any word, include plural referents unless clearly and explicitly defined as a single referent. As used herein, the term “comprising” and its grammatical variations are intended to be non-limiting, such that the description of items in the list does not exclude other similar items that may be substituted for or added to the listed items.

[0040] Unless otherwise stated, all quantitative values ​​are approximate, whether or not words such as "about" or "approximately" are used. The materials, methods, and examples provided herein are illustrative only and are not intended to be limiting.

[0041] Various embodiments provide porous membranes comprising short or discrete fibers and nanoparticles dispersed throughout at least a portion of the membrane. Such porous membranes can be configured as filter media and are particularly suitable for gas or liquid filters, including but not limited to air filters, face masks, gas turbine and compressor inlet filters, plate filters, cartridge filters, bag filters, clean-in-place (CIP) filters, battery separators, etc.

[0042] Various embodiments also provide systems, apparatus, and methods for producing porous membranes and products containing porous membranes (e.g., gas or liquid filters). Such systems and methods may include: isolating individual nanoparticles in a gaseous medium (e.g., air, helium, nitrogen, oxygen, carbon dioxide, etc.) (instead of a liquid) and dispersing the nanoparticles into the porous membrane via an airflow, aerosol, vaporizer, spray, or other suitable delivery mechanism.

[0043] While the following description focuses primarily on porous membranes and filtration media, it should be understood that the apparatus and methods disclosed herein can be readily adapted to a wide range of other applications. For example, the porous membranes disclosed herein can be used in household cleaning products, roofing and flooring products, automotive interiors and roof linings, reusable bags, wall coverings, filtration devices, insulation materials, and more. Furthermore, the isolated and generated individual nanoparticles can be used in a variety of coatings, composites, and / or additives, such as polymers, food packaging, flame retardants, fuel cells, battery packs, capacitors, nanoceramics, lamps, materials manufacturing, manufacturing methods, reinforcements for composites, cement, and other materials, medical diagnostic applications, medical therapeutic devices or therapies, tissue engineering (e.g., scaffolds for bone or tissue repair), drinking water, industrial process fluids, food and beverage products, pharmaceuticals and biologics, tissue imaging, medical therapy delivery, environmental applications (e.g., biodegradable compounds), and more.

[0044] The porous membrane preferably has an average pore size of less than about 10 micrometers. In an embodiment, the average pore size of the membrane is less than 5 micrometers, preferably less than 4 micrometers, and more preferably about 3.8 micrometers. Nanoparticles reduce the average pore size of the membrane while substantially maintaining the transmembrane pressure drop (e.g., bubble point).

[0045] In an exemplary embodiment, the membrane has a porosity value of at least 50% or 40%, preferably at least 20% or 5%. The porosity value is defined as the non-solid or pore volume fraction of the total material volume.

[0046] In the implementation, the filter has a bubble point of about 5 micrometers to about 50 micrometers, preferably less than about 30 micrometers, or less than about 20 micrometers, or less than about 10 micrometers, or about 5 micrometers.

[0047] Porous membranes can have a thickness suitable for a specific application. In some embodiments, the membrane has a thickness of about 0.2 mm to about 5 mm, preferably about 0.5 mm to about 3 mm.

[0048] The fibers considered for the substrate are preferably manufactured by a wet web-forming process, which typically comprises short or discrete fibers with a length of about 2 mm to about 15 mm, preferably about 4 mm to about 8 mm. The fibers are suspended in a fluid, such as water, in a large tank. The fibers can be mixed with viscose or wood pulp. After mixing, the aqueous fiber or pulp dispersion is pumped and continuously deposited onto a frame or molded web. The water is then evacuated until the fibers are substantially dry.

[0049] The cross-section of the fibers under consideration can have many shapes, including but not limited to circular, bean-shaped, dogbone-shaped, trefoil-shaped, barbell-shaped, bowtie-shaped, star-shaped, Y-shaped, etc. These shapes and / or other conventional shapes can be used in various embodiments to obtain the desired performance characteristics. The fibers in the substrate are held together by thermal bonding, chemical bonding, entanglement, or by using adhesives (such as glues).

[0050] The fiber can be a man-made fiber or a natural fiber. Suitable materials for the fiber include, but are not limited to, polypropylene, polyester (PET), PEN polyester, PCT polyester, polypropylene, PBT polyester, copolyamide, polyethylene, high-density polyethylene (“HDPE”), LLDPE, cross-linked polyethylene, polycarbonate, polyacrylate, polyacrylonitrile, polyfuran, polystyrene, styrene-maleic anhydride, polymethylpentene, cyclic olefin copolymers or fluorinated polymers, polytetrafluoroethylene, perfluoroethylene and hexafluoropropylene or copolymers with PVDF (such as P(VDF-TrFE)) or terpolymers (such as P(VDF-TrFE-... CFE), propylene, polyimide, polyetherketone, cellulose esters, nylon and polyamide, polymethacrylic acid, poly(methyl methacrylate), polyoxymethylene, polysulfonate, acrylic acid, styrene-acrylic acid, pre-oxidized acrylic acid, fluorinated acrylic acid, vinyl acetate, vinyl acrylic acid, ethylene vinyl acetate, styrene-butadiene, ethylene / vinyl chloride, vinyl acetate copolymer, latex, polyester copolymer, carboxylated styrene acrylic acid or vinyl acetate, epoxy resin, acrylic multipolymers, phenolic resin, polyurethane, cellulose, PVOH, PVA, styrene or any combination thereof. Other conventional fiber materials are also considered.

[0051] In some embodiments, the short fibers comprise polyolefins, polyesters, polyethylene (PE), polypropylene (PP), blends of PP and PE, PBT, PET, CoPET, PLA, PA, PHB, polyamides, and combinations thereof. In a preferred embodiment, the fibers comprise polyesters.

[0052] The fibers can include fibers of varying sizes, typically having a diameter of about 1 to about 1000 micrometers. The fibers can be configured as a gradient density medium, where the pore size decreases from the upper surface (upstream) to the lower surface (downstream) of the filter to increase capture efficiency and dust holding capacity. This configuration also allows for the dispersion of different amounts of nanoparticles at different depths within the filter medium. For example, the upstream side of the filter medium can have the largest fiber size to allow for more void space and a higher nanoparticle density, while the downstream side of the filter medium has smaller fibers to provide a lower nanoparticle density. Alternatively, this structure can be inverted to provide a higher nanoparticle density in the downstream portion of the filter medium.

[0053] The porous membranes discussed herein can include structures of individual fibers or filaments interwoven, interlocked, or bonded together. Porous membranes can also include sheet or web structures bonded together by mechanical, thermal, or chemical entanglement of fibers or filaments (and by perforated membranes). They can be substantially flat porous sheets made directly from individual fibers or molten plastic or plastic films.

[0054] In some implementations, the porous membrane may comprise knitted and / or woven materials. Knitted materials may include any knitted pattern suitable for the desired application. Suitable knitted materials for filter applications include weft knitting, warp knitting, knitted mesh, compressed knitted mesh, etc. Suitable woven materials for filter applications include textile filter media, such as monofilament fabrics, multifilament fabrics, nylon mesh, polyester mesh, polypropylene mesh, etc. Woven textiles can be used for, for example, mesh filter press filter cloths, woven filter pads and other die-cut parts, centrifuge filter bags, liquid filter bags, dust collector filter bags, bed dryer filter bags, rotary drum filters, filter belts, leaf filters, spiral wound media, etc.

[0055] Fibers in the medium can be held together by thermal bonding, chemical bonding, or entanglement. Bicomponent fibers can be used, particularly in mechanical filtration, and these fibers are formed by extruding two polymers from the same spinneret, both polymers being contained within the same filament. Suitable materials for bicomponent fibers include, but are not limited to, polypropylene (PP) / polyethylene (PE), polyethylene terephthalate (PET) / polypropylene (PP), etc. Alternatively, fibers in the medium can be bonded to other fibers using adhesive fibers such as polyvinyl alcohol.

[0056] The fibers can have a thickness suitable for the application. In some embodiments, at least one size of the fiber is about 1 to about 10,000 micrometers, or about 1 to about 1,000 micrometers, or about 10 to 100 micrometers. The thickness of the fiber can also be measured in deniers, which is a unit of measurement for the linear mass density of the fiber. In some embodiments, the linear density of the fiber can be about 1 denier to about 10 deniers. The nanoparticles are at least one fiber with a size of about 1 to about 1,000 nanometers or about 1 to about 100 nanometers. The size of the aforementioned fibers and nanoparticles can be diameter or width, depending on the shape of the fiber or nanoparticle.

[0057] For gas filters, such as pleated or non-pleated air filters, the linear density of the fibers can be from about 1 denier to about 10 denier. The filter media can contain fibers with the same or different linear deniers. The linear density of fibers in air filters is typically about 3-6 denier or less to ensure that the fibers are small enough to capture contaminants passing through the filter. The applicant has unexpectedly discovered that fibers can have even greater linear deniers, for example, greater than 3 denier, by using nanoparticles dispersed in the filter media. This is because nanoparticles provide significant filtration capacity. In some cases, the linear density of the fibers can be greater than 3 denier, 5 denier or greater, 6 denier or greater, or even as large as 7-10 denier.

[0058] For liquid filters, the linear density of the fibers can be from about 3 denier to about 1 denier, preferably from about 0.1 to about 5 denier.

[0059] In some embodiments, the filter includes one or more support layers bonded to the filter medium. The support layers and / or the filter medium may include nanoparticles dispersed at a certain depth within the layers. In some embodiments, a polymer layer, membrane, or thin film is provided, including one or more pores for gas or liquid to flow through, wherein the nanoparticles are arranged at a certain depth within the polymer layer. In other embodiments, the material includes a flexible surface layer for use in finger bandage pads, face masks, etc.

[0060] In some embodiments, at least one size of the nanoparticle is less than about 20 micrometers. In some embodiments, at least one size of the nanoparticle is less than 1 micrometer (i.e., diameter, width, height, etc., depending on the cross-sectional shape of the fiber). In other embodiments, the nanoparticle comprises at least one microfiber or nanofiber with a size of about 1 micrometer to about 20 micrometers. For example, microfibers or nanofibers with a diameter or width less than 1 micrometer and a length greater than 1 micrometer are nanoparticles as used herein. In an exemplary embodiment, at least one size of the microfiber is about 5 micrometers. The nanoparticle may have a continuous length, or the nanoparticle may have a discrete length, for example, from 1 to 100,000 micrometers, preferably from about 5 to 10,000 micrometers, or from about 5 to about 1,000 micrometers, or from about 100 to about 600 micrometers.

[0061] In some embodiments, each individual nanoparticle can be a small particle with a size of about 1 to about 1000 nanometers, preferably about 100 to about 750 nanometers. In the number-size distribution, at least half of the particles can be measured to be 800 nanometers or less. As the size of nanoparticles approaches the nanoscale, the material properties change. This is due to the increased surface area to volume ratio, resulting in the surface atoms of the material dominating the material properties. Because of the extremely small size of nanoparticles, their surface area to volume ratio is very large when compared to bulk materials (e.g., powders, plates, sheets, or even larger fibers). This characteristic gives nanoparticles unexpected optical, physical, and chemical properties because they are small enough to confine their electrons and produce quantum effects.

[0062] In some embodiments, the nanoparticles are dispersed "at a certain depth" within the substrate. As used herein, the term "at a certain depth" means that the nanoparticles are dispersed across a first surface of the substrate such that at least some of the nanoparticles are disposed between the first and second opposing surfaces within the internal structure of the substrate or medium. In some embodiments, the nanoparticles are substantially dispersed throughout the entire medium from the first surface to the opposing second surface. In other embodiments, the nanoparticles are dispersed within a portion of the medium at a location from the first surface to the first and second surfaces.

[0063] In some implementations, the nanoparticles are three-dimensionally distributed in space relative to the supporting fibers, which can increase the surface area of ​​the fibers and the micro-volumes within the nonwoven material. This three-dimensional distribution also prevents complete clogging of specific sections of the nonwoven material, which is particularly useful in filter media as it allows fluids (e.g., air or other gases) to pass through the filter, thereby reducing the overall pressure drop across the filter.

[0064] In other embodiments, the nanoparticles are arranged with a density gradient across the thickness of the substrate, such that the density of nanoparticles disposed near a surface is higher than that of the opposite surface, or the density of nanoparticles disposed on the surface is higher compared to the middle portion of the substrate. The density gradient can be substantially linear, it can decrease in the form of a series of discrete steps, or the gradient can be random (i.e., the decrease in density is typically not linear or stepwise). Such a density gradient provides many advantageous features for certain applications (e.g., filters) (discussed below).

[0065] Nanoparticles can include any suitable material, such as glass, biosoluble glass, non-bio-durable glass fiber, ceramic materials, acrylic acid, carbon, metals (e.g., alumina), polymers (e.g., nylon, polyethylene terephthalate, etc.), polyvinyl chloride (PVC), polyolefins, polyacetals, polyesters, cellulose ethers, polyalkylene sulfides, poly(aryl oxides), polysulfones, modified polysulfone polymers, and polyvinyl alcohol, polyamides, polystyrene, polyacrylonitrile, polyvinylidene chloride, polymethyl methacrylate, polyvinylidene fluoride, fibrillated cellulose, and any combination thereof.

[0066] In some embodiments, the nanoparticles can be produced as bicomponent segmented discs and islands. The filaments are then stretched to obtain submicron filaments. The continuous filament nanofibers are cut to the desired length (preferably about 100 to about 10,000 micrometers).

[0067] In some embodiments, the nanoparticles are absorbents and adsorbents. In some embodiments, the nanoparticles are activated carbon fibers or activated carbon powder. In some embodiments, the nanoparticles are catalytic particles or catalytic fibers. In some embodiments, nanoparticles can be obtained by feeding submicron fiber nonwoven fabric into a pulverizer, crusher, or trimmer, wherein the bonded nonwoven fabric enters and yields chopped fibers. For example, submicron nanoparticles can be obtained by feeding low-weight bio-component meltblown or nano-meltblown fabric into a pulverizer.

[0068] In some implementations, different nanoparticles can be mixed. For example, nanofibers and nanobeads can be mixed. Two different nanofibers with different melting points can also be mixed, allowing the lower-melting-point nanoparticles to act as a binder for the higher-melting-point nanofibers. Nanoparticles with different diameters and lengths can also be mixed.

[0069] In some embodiments, the nanoparticles are selected from environmentally sustainable raw materials. Nanoparticles may include biosoluble glass nanofibers, biodegradable nanoparticles, compostable nanoparticles, fibrillated cellulose, cellulose, or recyclable compositions.

[0070] Different types of nanoparticles can be combined. Some nanoparticles can be functional nanoparticles. For example, functional nanoparticles may include activated carbon and / or antibacterial materials deposited on and / or attached to fibers in nonwoven materials. This can improve the gas absorption efficiency of the fibers and their effectiveness in killing bacteria. Furthermore, nonwoven products in which microfiber nonwovens with deposited glass nanoparticles and carbon nanoparticles can provide filtration and deodorization functions as filter media.

[0071] In some embodiments, nanoparticles are bonded to fibers via mechanical entanglement. This mechanical bonding can be supplemented with adhesives or binders, as discussed in more detail below. In some embodiments, the nanoparticles are not curled (i.e., they do not include the pronounced wavy, curved, coiled, serrated, or similar shapes associated with nanoparticles in a relaxed state). In other embodiments, the nanoparticles may have a curled structure with discrete lengths. For example, when these curled nanofibers with discrete lengths are attached to fibers, they become entangled with each other and are also firmly attached to, onto, and around the fibers, thereby forming modified fibers. In other embodiments, the attachment of nanofibers to microfibers is achieved via electrostatic attraction and / or van der Waals attraction between the fibers and nanoparticles.

[0072] Figure 1 A cross-sectional view of a porous membrane 10 is shown, the porous membrane comprising a plurality of fibers 12 and nanoparticles 14. The membrane 10 has a first surface 16 and a second surface 18 opposite to the first surface 16, defining a width or thickness between the first and second surfaces 16, 18. The nanoparticles 14 have been deposited into the membrane through the first surface 16. As shown, the nanoparticles 14 penetrate through the first surface 16 to a “certain depth” between the first and second surfaces 16, 18 of the membrane 10. In some embodiments, the nanoparticles 14 penetrate at least 25% of the width or thickness, or more preferably at least about 50% of the thickness, between the first and second surfaces 16, 18. In other embodiments, the nanoparticles 14 substantially penetrate the entire membrane from the first surface 16 to the second surface 18.

[0073] Nanoparticles 14 preferably comprise individual nanoparticles that have been broken up, separated, and isolated from each other before being dispersed into membrane 10. Therefore, nanoparticles 14 do not exist in the membrane as a layer, and there are no obvious clumps or bundles of nanofibers. This provides better dispersion of the nanoparticles throughout the membrane, which, in some applications (e.g., liquid filters), reduces the average pore size of the membrane. Furthermore, this provides a porous membrane with a higher areal density (in grams per square meter (gsm)) or “additional amount” of nanoparticles within the material. As used herein, the term “additional amount” refers to the areal density (gsm) of a material, fiber, or particle in a thin layer, sheet, or membrane of material.

[0074] In some implementations, the nanoparticles may contain approximately 0.1 g / m³. 2 Approximately 20 g / m 2 Preferably, it should be at least about 2.0 g / m 2 The specific amount added, or areal density, can vary depending on the application. For example, the applicant has found that higher areal density or addition amounts reduce the average pore size of the membrane. Therefore, the specific amount of nanoparticles added can depend on the desired efficiency of the filtration media.

[0075] Figure 2 A cross-sectional view of a porous membrane 20 is shown, which includes a plurality of fibers 12 and nanoparticles 14. As shown, the nanoparticles 14 penetrate the entire width of the membrane 20 from the first surface 16 to the second surface 18. In some embodiments, the nanoparticles 14 are substantially dispersed throughout the fibers 12 of the membrane, such as... Figure 2 As shown. In some embodiments, the density of nanoparticles located at the first surface 16 differs from the density of nanoparticles dispersed in the central portion of the film 20 between surfaces 16 and 18 by less than 50%. In some embodiments, this difference is less than 25%, preferably less than 10%. In some embodiments, the amount or number of individual nanoparticles dispersed in the central portion of the film 20 is at least about 50% of the amount of individual nanoparticles dispersed at or near the first surface 16, preferably at least about 75%, and more preferably at least about 90%.

[0076] In other embodiments, the nanoparticles 14 are arranged in a density gradient from the first surface 16 to the second surface 18. For example, Figure 3A cross-sectional view of the film 30 is shown, in which nanoparticles 14 form a density gradient, wherein the density of nanoparticles 14 disposed near the first surface 16 is higher than that of the second surface 18. In some embodiments, the density of nanoparticles located at the first surface 16 differs from the density of nanoparticles dispersed at the second surface 18 by more than about 75%. In some embodiments, this difference is greater than 50%. In some embodiments, this difference is greater than 25%. In some embodiments, the amount or number of individual nanoparticles dispersed at or near the second surface 18 is less than about 50% of the amount of individual nanoparticles dispersed at or near the first surface 16, preferably less than about 25%, and more preferably less than about 10%.

[0077] Figure 3 The density gradient shown from the first surface 16 to the second surface 18 can be substantially linear. Alternatively, the density of the nanoparticles 14 can decrease from the first surface 16 to the second surface 18 in the form of a series of discrete steps, or the gradient can be random (i.e., the decrease in density is generally not linear or stepwise).

[0078] In other embodiments, nanoparticles can be added to the film from both the first surface and the second surface 16, 18. In these embodiments, the areal density or "addition amount" at the first surface and the second surface 16 and 18 can be substantially equal to each other, or they can vary depending on the application. In these embodiments, the areal density or "addition amount" present in the middle of the substrate is lower than the areal density or "addition amount" at surfaces 16 and 18. For example, the areal density in the middle of the film can be about 75% of the areal density at surfaces 16 and 18, or it can be about 50%, 40%, or 25%.

[0079] Imaging techniques can be used, for example, to measure the distribution of nanoparticle thickness across the membrane. Using an electron microscope or other techniques, a magnified image of the membrane is taken at a horizontal cross-section of the product at the midpoint of its thickness. This image can be compared to images taken at the top or bottom surface of the product, or all three images can be compared to determine the degree of variation in the amount of deposited nanoparticles. Computer image analysis can be employed. For example, in... Figure 3In this process, cross-sections can be taken at point AA and at point BB. Top views of each cross-section can be obtained using electron microscopy, scanning electron microscopy, and other microscopes. For example, the top view of the cross-section taken at point AA can be compared with the top view taken at point BB. The number of microfibers, nanoparticles, or both in samples of the same two-dimensional size can be evaluated and compared. Furthermore, imaging techniques can be used on three-dimensional samples. These techniques can be used to evaluate fiber orientation and other properties. These techniques can be used to determine whether nanoparticles have been deposited to a certain depth in the substrate, substantially deposited in most of the substrate, substantially deposited throughout the entire depth of the substrate, or deposited at a certain depth in the substrate.

[0080] The applicant has also discovered that, in some applications, fibers with a greater linear density (e.g., greater than about 3 denier) than those used in conventional filters provide more open spaces or pores within the filter media, allowing nanoparticles to be dispersed therein at a greater density. While this may seem counterintuitive to those skilled in the art, the applicant has found that fibers with a greater linear density incorporating nanoparticles improve the overall efficiency of the filter.

[0081] In some embodiments, the filter medium may include at least two different fiber thicknesses or linear densities to provide at least two different filter layers within the same filter medium. For example, in some cases, a portion of the filter medium will include fibers with a linear density greater than 3 denier, 5 denier, or greater, or 6 denier, or greater. Another portion of the filter medium will include fibers with a more standard linear density of 3 denier or less. This dual-layer filter medium creates a first filter section and a second filter section, the first filter section primarily using high-density nanoparticles within the thicker fibers to filter contaminants, and the second filter section primarily using fibers with a lower linear density to filter contaminants, but both sections may include nanoparticles dispersed throughout the fibers. In some embodiments, the filter medium may include three or more separate sections or layers, each with a different denier fiber range.

[0082] Figure 4A cross-sectional view of a dual-layer filter medium is shown, comprising a first porous membrane 40 having a first surface 42 and a second surface 44 opposite to the first surface, and a second porous membrane 50 having a first surface 52 and a second surface 54 opposite to the first surface. The second surface 44 of the membrane 40 is bonded to the second surface 54 of the first membrane in any manner known to those skilled in the art. The first membrane 40 comprises fibers 46 with a relatively low linear density, for example, about 3 denier or less. The second membrane 50 comprises fibers 56 with a relatively high linear density, for example, about 3 denier or greater, such as 5 denier, 6 denier or greater. The second membrane 50 also comprises individual nanoparticles 58 dispersed throughout the fibers 56 and bonded to and / or retained by the second membrane 50. The first membrane 40 may or may not contain nanoparticles.

[0083] The first membrane 40 is configured to primarily use fibers 46 to filter contaminants, but as previously mentioned, the first membrane 40 may also contain nanoparticles. The second membrane 50 is configured to use both fibers 56 and nanoparticles 58 to filter contaminants.

[0084] In some embodiments, the porous membrane may contain additives, such as antibacterial and / or antiviral compositions, such as silver, zinc, copper, organosilicon, tributyltin, and organic compounds containing chlorine, bromine, or fluorine compounds.

[0085] Fibers can include biological component fibers, which consist of two or more different fibers bonded together. Fibers can contain the same material or different materials.

[0086] Figures 5A-5C Different examples of bio-component fibers that can be used with the porous membranes disclosed herein are shown. Figure 5A A fiber 60 having a core fiber 62 and surrounding sheath fibers 64 is shown. In this embodiment, the core 62 and the sheath are substantially concentric. Figure 5B A bio-component fiber 70 is shown having a first fiber and a second fiber 72 and 74 arranged side by side. Figure 5C A biocomponent fiber 80 with core fibers 82 and sheath fibers 84 is shown. In this embodiment, the core 82 is not concentric with respect to the longitudinal axis of the sheath 84, which increases the overall bulkiness of the biocomponent fiber. Of course, other configurations are also possible. For example, the core can contain shapes other than circular, such as dog bone shape, square, triangle, rhombus, etc. Alternatively, the fiber can contain multiple cores, or it can be divided into three, four or more quadrants.

[0087] In some embodiments, the fibers may include a silicone-based coating to improve the efficiency of the filter media in capturing contaminants, particularly those in the E2 and E3 particulate groups. The silicone-based coating may include a reactive silicone emulsion. Silicone emulsions may include, for example, dimethyl silicone emulsions, amino-based silicone emulsions, organofunctional silicone emulsions, resin-based silicone emulsions, film-forming silicone emulsions, etc. In one embodiment, the reactive silicone emulsion comprises an amino-functionalized polydimethylsiloxane and / or polyethylene glycol monotridecyl ether. Suitable silicone coatings are described in commonly assigned U.S. Provisional Patent Application Serial No. 63 / 406,686, filed September 14, 2022, the full disclosure of which is incorporated herein by reference.

[0088] In some embodiments, the filter media may be notched, pleated, or folded into a pleated filter. Pleats can be formed by a variety of conventional pleating operations, including but not limited to rod-type, rotary, and star-wheel-type pleating operations. The filter includes one or more support layers bonded to the filter media. In some embodiments, a polymer layer, membrane, or thin film is provided, which includes one or more pores for gas or liquid to flow through. In other embodiments, the material includes a flexible surface layer for use in finger bandage pads, face masks, etc.

[0089] In some embodiments, fibers may be included or incorporated into a film or layer comprising pores, voids, or perforations. The pores may be embossed into a pattern (e.g., circular, rhomboid, hexagonal, rectangular, triangular, or square), and then stretched until pores are formed in the thinned areas created by the embossing. Such porous substrates may be formed from a variety of polymers, such as polypropylene, polyethylene, high-density polyethylene (“HDPE”), etc. The polymer layer may, for example, comprise an extruded film. Porous films are commercially available and sold under the trademark Delnet®. The substrate is supplied in roll form, with the nanofibers deposited into the substrate during a roll-to-roll process.

[0090] In some embodiments, the porous membrane (i.e., fibers and / or nanoparticles) may be electrostatically charged, enabling the capture of contaminants, for example, by mechanical and electrostatic filtration. The bonding between the fibers and nanoparticles can also be enhanced by electrostatically charging the nanoparticles, fibers, or both. For example, in some embodiments, the fibers are electrostatically charged, allowing mechanical filtration through the nanoparticles while simultaneously enabling electrostatic filtration through an electret substrate. The electrostatic or electret substrate may be a highly porous triboelectric filter medium manufactured by combing and needle punching. In one embodiment, it is preferable to deposit the nanoparticles into the substrate prior to needle punching, and then needle the electrostatic fibers and nanoparticles together.

[0091] Electrostatic charging of membranes, nanoparticles, or both can be performed using triboelectric methods, corona discharge, electrostatic fiber spinning, hydrocharging, charging rods, or other known methods. Corona charging is suitable for charging single polymer fiber blends or fabrics. Triboelectric charging can be applied to charging fibers with different electronegativity. Electrostatic fiber spinning combines polymer charging and fiber spinning into a one-step process. Methods suitable for triboelectric charging are described in commonly assigned U.S. Provisional Patent Application No. 63 / 410,729 and U.S. Patent No. 9,074,301, filed September 28, 2022, the entire disclosure of which is incorporated herein by reference for all purposes.

[0092] Filter media may contain charge additives to alter the triboelectric charge on the fibers and increase the stability and / or duration of the triboelectric charge in the filter. This improves the overall filtration efficiency of the filter without compromising other important properties such as lifespan, dust holding capacity, and pressure drop or airflow through the filter. A description of charge additives suitable for triboelectric charging is given in commonly assigned U.S. Provisional Patent Application Serial No. 63 / 410,731, filed September 28, 2022, the entire disclosure of which is incorporated herein by reference for all purposes.

[0093] Nanoparticles with different triboelectric properties relative to fibers can be selected to enhance particle removal by utilizing the triboelectric effect. In this method, the generated nanoparticles are formed in an electric field and are less susceptible to contamination by chemicals that can mitigate the triboelectric effect. Nanoparticles with different adsorption properties or surface charge characteristics than coarse fibers can also be used, for example, for oil or water filtration. This difference can be used to enhance or create a local electric field gradient within the filter media to enhance particle removal. Nanoparticles and coarse fibers can have different wetting properties.

[0094] The membrane may contain adhesives or bonding materials, such as glues or binders, to promote adhesion between fibers and / or retention of nanoparticles in the membrane, allowing the nanoparticles to adhere to the fibers or otherwise be retained by the fibers within the substrate to form a stable matrix. The adhesives or bonding materials are preferably present in relatively small amounts to bond individual nanoparticles to the fibers throughout the substrate.

[0095] Adhesives can include a variety of conventional materials, including natural-based materials such as starch, dextrin, guar gum, etc., or synthetic resins such as EVA, PVA, PVOH, SBR, polyglycolic acid, etc. In some embodiments, solvent-based adhesives are used, wherein bonding occurs when the solvent evaporates.

[0096] In one preferred embodiment, the adhesive or bonding material comprises dextrin. In yet another embodiment, the adhesive comprises a composition of various substances (e.g., water, 2-hexyloxyethanol, isopropanolamine, sodium dodecylbenzenesulfonate, laurylamine oxide, and ammonium hydroxide). In yet another embodiment, the adhesive comprises at least PVOH. The adhesive can be a solution, emulsion, suspension, hot melt, curable, pure, and / or combination thereof.

[0097] In some embodiments, an adhesive resin is used, and the adhesive resin can be cross-linked after the adhesive is applied to the substrate. Adhesion (water resistance / solvent resistance) can be promoted by self-cross-linking during solvent evaporation in the adhesive formulation or by thermal activation during the drying process. In some adhesives, cross-linking can be achieved by high-energy wavelength electromagnetic radiation (including but not limited to RF, UV, or electron beams). The amount of adhesive can be controlled by adjusting the nozzle size of the spray gun 140 or by controlling the flow rate of the adhesive composition. The adhesive can be applied using a nozzle, dip coating, or other methods.

[0098] In some embodiments, the adhesive or bonding material may include a surfactant to reduce the surface or interfacial tension of the adhesive, thereby increasing its dispersibility and wetting properties, and making it easier for the adhesive to penetrate into a film to a certain depth. Suitable surfactants for use with the adhesives disclosed herein include nonionic, anionic, cationic, and amphoteric surfactants, such as sodium stearate, 4-(5-dodecyl)benzenesulfonate, sodium dodecylbenzenesulfonate wetting agents, docusate (sodium dioctyl sulfonate), alkyl ether phosphates, benzalkonium chloride (BAC), perfluorooctane sulfonate (PFOS), etc.

[0099] In some embodiments, the membrane comprises its own adhesive composition. In these embodiments, the adhesive or bonding material may or may not be added to the membrane. In one such embodiment, the substrate comprises bio-component fibers, wherein one of the components comprises an outer sheath at least partially surrounding an inner core (see...). Figure 5A and 5C ).

[0100] The sheath may contain a material that binds the nanoparticles. For example, the sheath may contain a material that becomes viscous and / or fluid upon heating and / or drying. During the heating / drying step (discussed below), the sheath portion of the fiber is heated to its melting point until it becomes viscous and / or fluid to bind the nanoparticles to the substrate. In a preferred embodiment, bonding and drying are performed simultaneously.

[0101] Figure 6A representative liquid filter 109 produced using porous membranes in various embodiments is shown. The porous membranes are rolled into cylinders, cones, or other suitable shapes and can be used in applications such as gas turbine and compressor inlet filters, and plate filters. The cartridge is a tubular filter medium encapsulated within a housing. The flow direction in the cartridge filter is from the outside to the inside of the cartridge. The cartridge is typically made of synthetic or natural fibers and small metal wires. A core made of stainless steel, tin-plated steel, or polypropylene is present along the axis of the tubular cartridge to support the media material. A purer filtrate is collected at the core.

[0102] Figure 7 A representative bag filter 110 manufactured using porous membranes in various embodiments is shown. The bag filter 110 includes a porous membrane having short fibers and nanoparticles dispersed at a certain depth within a substrate. Bag filters are among the most popular filtration devices. In this device, the liquid to be processed passes through a permeable bag with micropores that acts as the filter medium. Solid particles larger than the pores are trapped and accumulate inside the bag. Its end has a sealing ring, typically made of stainless steel or plastic, to secure the bag within the filter container.

[0103] Other types of filters that can be developed using the nonwoven materials disclosed herein include conical cartridges, pleated cartridges, wound cartridges, spunbond cartridges, square end cap cartridges, activated carbon cartridges, reverse osmosis membrane cartridges, alkaline cartridges, ultraviolet cartridges, bag filters, V-shaped compact filters, plate filters, pleated or non-pleated bag cartridges, clean-in-place (CIP) filters, etc.

[0104] In another embodiment, a porous membrane is incorporated into an air filter that removes particulate matter and contaminants from the air, such as a HEPA filter (i.e., a pleated mechanical air filter), a UV light filter, an electrostatic filter, a washable filter, a media filter, a rotating glass filter, a pleated or non-pleated air filter, an activated carbon filter, a pocket filter, a V-shaped compact filter, a filter disc, a flat wish filter, a cartridge filter, etc. The porous membrane may include the filter media used in the air filter and may be supported by a support layer, a loosely woven fabric layer, or may be included in other layers or materials. The applicant has discovered that incorporating nanoparticles to a certain depth into porous membranes as discussed herein significantly improves the efficiency of air filters without compromising other factors, such as the pressure drop across the filter (i.e., airflow). Furthermore, these materials increase the overall dust holding capacity, thereby increasing the filter's lifespan, particularly compared to filters that rely solely or primarily on electrostatic interactions to improve efficiency.

[0105] The porous membranes disclosed herein can also be used in medical face masks or other medical applications, such as filter cartridges in respirators. Medical face masks are designed to protect healthcare workers and / or patients from microorganisms and other materials. For example, medical masks can block bacteria (e.g., those approximately 3 micrometers in size) and viruses (e.g., those approximately 0.1 micrometers in size). The face mask is made of a multi-layered nonwoven material and has ear loops, straps, or other structures for attaching the mask to the face. Wires can be attached to at least the upper part of the mask so that at least that portion conforms to the face. The face mask may include a rigid polymer structure designed to hold the multi-layered nonwoven material in front of the face. In one example, the face mask has three layers. The outer and inner layers contain a nonwoven material (e.g., spunbond polypropylene) that provides breathability, but any material mentioned herein may also be used.

[0106] The porous membranes disclosed herein can also be used for solid-liquid separation, such as water purification. Water treatment systems can utilize membrane separation, in which any of the materials mentioned herein can be used.

[0107] In other embodiments, the filter includes a filter media and a substantially rigid support layer bonded to the filter media. The support layer comprises fibers and individual nanoparticles dispersed at a certain depth within the layer. The nanoparticles are configured to filter contaminants that pass through the support layer.

[0108] Figures 19A-19C These are microscopic images of high-density polyethylene (HDPE) nanoparticles dispersed on a substrate containing a carded fiber medium, as described herein. The substrate and nanoparticles were then calendered.

[0109] Figure 8 The entire system 110 for manufacturing the aforementioned nonwoven materials and other products is schematically illustrated. As shown, system 110 includes a feeder 120 for advancing a substrate 130 of nonwoven fibers or other materials during the manufacturing process. System 110 also includes a coating machine 140, a fiberizing system 150, and a heating and / or drying device 160. In some embodiments, system 110 further includes a vacuum or other negative pressure source 170 located below the substrate 130, opposite the fiberizing system 150.

[0110] In one embodiment, feeder 120 includes a winding machine 122 located downstream of the process and an unwinding machine 124 located upstream, which continuously winds the substrate 130 through system 100. In some embodiments, feeder 120 may also include a support surface (not shown) extending between the winding machines for supporting the substrate 130 as it moves downstream through system 100. In other embodiments, the substrate is unwound directly from unwinding machine 124 to winding machine 122 without the need for another support surface.

[0111] The coating machine 140 is configured to spray droplets of adhesive or bonding material (e.g., glue or adhesive) onto a substrate 130, allowing nanoparticles to adhere to fibers within the substrate 130 to form a stable matrix. The adhesive is preferably present in a relatively small amount to bind individual nanoparticles to the fibers throughout the substrate 130. In a preferred embodiment, the coating machine 140 includes a nozzle sized to generate adhesive droplets with a diameter of approximately 20 to 30 micrometers to increase the penetration depth of the adhesive through the substrate 130. Of course, droplet size can be affected by many other parameters, including air pressure, air volume, air temperature, humidity, spray nozzle design, the rheology / viscosity of the adhesive, carrier, etc.

[0112] Of course, it should be recognized that coating a substrate with an adhesive or bonding material can be achieved by other coating methods, including ultrasonic spraying, dip coating, spin coating, gravure coating, kiss roll coating, screen coating, powder coating, electrostatic coating, sputtering coating, or similar coating techniques.

[0113] As discussed above, adhesives can include a variety of conventional materials, including natural-based materials such as starch, dextrin, guar gum, etc., or synthetic resins such as EVA, PVA, PVOH, SBR, etc. In some embodiments, solvent-based adhesives are used, wherein bonding occurs when the solvent evaporates.

[0114] In one preferred embodiment, the adhesive comprises dextrin. In another embodiment, the adhesive comprises a composition of various substances, such as water, 2-hexyloxyethanol, isopropanolamine, sodium dodecylbenzenesulfonate, laurylamine oxide, and ammonium hydroxide. In yet another embodiment, the adhesive comprises PVOH. The adhesive can be a solution, emulsion, suspension, hot melt, curable, pure, and / or combination thereof.

[0115] In some embodiments, an adhesive resin is used, and the adhesive resin can be cross-linked after the adhesive is applied to the substrate 130. Adhesion (water resistance / solvent resistance) can be promoted by self-cross-linking during solvent evaporation in the adhesive formulation or by thermal activation during the drying process. In the case of some adhesives, cross-linking can be achieved by electromagnetic radiation of high-energy wavelengths (including but not limited to RF, UV, or electron beams). The amount of adhesive can be controlled by adjusting the nozzle size of the sprayer 140 or by controlling the flow rate of the adhesive composition.

[0116] In some embodiments, the adhesive may include a surfactant to reduce the surface or interfacial tension of the adhesive, thereby increasing its dispersibility and wetting properties, and making it easier for the adhesive to penetrate into a substrate to a certain depth. Suitable surfactants for use with the adhesives disclosed herein include nonionic, anionic, cationic, and amphoteric surfactants, such as sodium stearate, 4-(5-dodecyl)benzenesulfonate, sodium dodecylbenzenesulfonate wetting agents, docusate (sodium dioctyl sulfonate), alkyl ether phosphates, benzalkonium chloride (BAC), perfluorooctane sulfonate (PFOS), etc.

[0117] In some embodiments, the sprayer 140 is located upstream of the fiberization system 150 to spray the adhesive before the nanoparticles are deposited. In other embodiments, the sprayer 140 is located downstream of the fiberization system 150 so that the adhesive can be sprayed after the nanoparticles are deposited. In other embodiments, the system 100 includes two sprayers; one is located upstream of the fiberization system 150, and a second sprayer (not shown) is located downstream of the fiberization system 150 to coat the substrate 130 with a second adhesive after the nanoparticles are deposited.

[0118] In some implementations, each sprayer 140 has more than one nozzle head. For example, the nozzle heads may be arranged in series to achieve better uniformity or increase the fiber spraying width. Alternatively, the nozzle heads may be placed parallel (i.e., across the width of the substrate) to ensure that the adhesive is applied across the entire width of the substrate.

[0119] In a preferred embodiment, a negative pressure source or vacuum source (not shown) is arranged below the substrate 130, opposite the sprayer 140, to increase the penetration depth and uniformity of the adhesive. The negative pressure source can be any suitable suction device that draws the adhesive through the substrate, such as a suction pump.

[0120] In some embodiments, the substrate comprises its own adhesive composition. In these embodiments, the adhesive may or may not be added to the substrate. In one such embodiment, the substrate comprises bio-component fibers 600, wherein one of the components comprises an outer sheath 64 at least partially surrounding an inner core 62. In some embodiments, the sheath 64 and the core 62 may be substantially concentric with each other. Figure 5A In other embodiments, the core 84 may not be concentric with the sheath 82. Figure 5C In other embodiments, the core 72 and the sheath 74 can be placed side by side with each other. Figure 5B Of course, other configurations are also possible. For example, core 184 can contain shapes other than circular, such as dogbone, square, triangle, rhombus, etc. Alternatively, fiber 180 can contain multiple cores, or it can be divided into three, four or more quadrants.

[0121] The sheath 64 may contain a material that binds the nanoparticles. For example, the sheath 64 may contain a material that becomes viscous and / or fluid upon heating and / or drying. During the heating / drying step, a portion of the sheath 64 of the fiber is heated to its melting point until it becomes viscous and / or fluid to bind the nanoparticles to the substrate. In a preferred embodiment, bonding and drying are performed simultaneously within the drying apparatus 160.

[0122] Figure 9 A fibrillation system 150 for converting nanofiber groups into individual nanoparticles is schematically illustrated. As used herein, the term "fibrillation" means converting (e.g., opening, separating, isolating, and / or individualizing) clusters, clumps, or other groups of nanoparticles that may or may not be entangled into each other into at least one individual nanoparticle with a size less than 1 micrometer. Figure 10-12 Large tangled nanofiber clusters were shown. Figure 10 Smaller tangled nanofiber clusters Figure 11 ) and individual nanoparticles ( Figure 12 Examples of ).

[0123] As shown, the fiberization system 150 includes a feeder 200, such as a hopper, for feeding larger or larger clusters / agglomerates of nanoparticles (see [reference]). Figure 10 The feeder 200 can comprise any suitable hopper device known to those skilled in the art and is preferably configured to introduce large particle clusters into the process at a specified rate, which will depend on the rate of downstream fibrosis. The nanoparticles can be introduced continuously at the specified rate or at intervals at a specific rate. Bundles of large nanoparticle clusters can be broken up before being introduced into the feeder 200.

[0124] It should be recognized that nanoparticles can be introduced into the fibrosis device 150 in a variety of different forms. For example, pristine nanofibers can be produced as long, separated fibers. In this form, the nanofibers can be cut to obtain the desired length-to-diameter ratio.

[0125] System 150 also includes a separator 210, such as a mixer, for separating or breaking down large nanoparticle clusters / agglomerates into smaller nanoparticle clusters / agglomerates (see [link to documentation]). Figure 11 The feeder 200 conveys nanofibers into the separator 210 in a stable and continuous manner by any mechanical means. The conveying speed will depend on various factors, such as the speed of the substrate 130 along the feeder 120, the fiberization rate of the nanoparticles, etc. By controlling the amount of nanoparticles falling into the separator 210, the amount of nanoparticles dispersed in the substrate can be controlled, thereby achieving a continuous manufacturing process.

[0126] In one embodiment, the separator 210 includes a housing 212 having a first opening 214 coupled to a feeder 200 and a second opening 216 coupled to a downstream process. The second opening 216 is preferably sized to allow only nanofiber clusters of a given size to pass through. The separator 210 may include a plurality of rotatable blades (not shown) designed to rotate about a vertical axis within the housing 212 to separate and open coarse nanofiber clusters. The blades may have the same or different pitch and camber to allow entangled fibers to sequentially break down or “open” as they are conveyed from the first opening 214 to the second opening 216.

[0127] The fiberization system 150 also includes an airflow extending throughout the system from the separator 210 to the nozzle 220 (discussed in more detail below). The airflow (along with a series of pumps discussed below) provides the power to move the nanofibers through the system 150. In one embodiment, the airflow is generated by an air compressor 230 configured to supply compressed air to the system, but it should be recognized that other forms of gas can be used to deliver the nanofibers through the system 150.

[0128] System 150 includes one or more pumps for moving nanofiber clusters and ultimately individual nanoparticles throughout the system. The pumps can include any suitable pump, such as a positive displacement pump, centrifugal pump, axial flow pump, etc. In one embodiment, a first pump 240 includes a first inlet fluidly coupled to an air compressor 230 via a first channel 242 and a second inlet fluidly coupled to a separator 210 via a second channel 244. Compressed air is drawn into the first pump 240, which creates a negative pressure (e.g., a vacuum) to draw the nanofiber clusters from the separator 210 into the pump (discussed in more detail below). System 150 may also include a second pump and a third pump 250, 260, each fluidly coupled to the outlet of the first pump 240. Similarly, the second and third pumps 250, 260 create a negative pressure to draw the nanofiber clusters through a third channel 252.

[0129] In some embodiments, pump 240 includes injector 300. For example... Figure 13 As shown, each ejector 300 includes a power fluid inlet 302 and a nanofiber inlet 304, which are coupled to an outlet 306 via a fluid channel 308. The fluid channel 308 includes a converging inlet nozzle 310, a diffuser throat 312, and a diverging outlet diffuser 314. High-pressure, low-velocity air is converted into low-pressure, high-velocity air, thereby generating the pressure difference required for suction. Based on the Venturi effect and Bernoulli's principle, a primary fluid medium (e.g., compressed air) is used to create a vacuum to draw the nanofibers into the ejector 300 and discharge them through the outlet 306. The diameter of the ejector 300 depends on the volumetric velocity of the compressed air, the suction requirement, the pressure drop, and the fluid pressure of the compressed air.

[0130] review Figure 9 The third channel 252 includes a connector 254 that divides the third channel 252 into two independent channels, each leading to a second pump and a third pump 250, 260. The connector 254 preferably includes a surface or wall arranged substantially perpendicular to the third channel 252, thereby forming a T-shaped intersection. This surface can be any surface that obstructs the flow of nanofibers through the channel, such as the inner wall of the channel at the junction, or other inner walls that change direction, such as curved surfaces, vertical surfaces, etc. Alternatively, the channel can include a wall or other surface arranged within the channel or protruding into the channel in the fluid path. In one embodiment, the channel extends to a substantially T-shaped connector comprising two independent channels extending from the connector. The second injector is configured to draw nanofibers into the T-shaped connector at a speed sufficient to disperse at least some of the nanofibers.

[0131] As the nanofiber clusters move through the third channel 252, they are propelled toward the surface or wall by the negative pressure applied by the second and third pumps 250, 260. The velocity of the nanofibers relative to the connector 254 generates collisions with sufficient kinetic energy, causing at least some nanofiber clusters to break down into smaller nanofiber clusters and / or into at least one individual nanoparticle with a size less than 1 micrometer.

[0132] To generate the kinetic energy required to decompose the nanofiber clusters, air is propelled throughout the system 150 at a speed of approximately 500 feet per minute (fpm) to approximately 10,000 feet per minute, preferably approximately 2,000 fpm to approximately 6,000 fpm. System 150 includes a sufficient amount of suction pressure, preferably at least approximately 20 psi. This suction pressure generates a total pressure of at least approximately 100 psi throughout the system.

[0133] In some embodiments, system 150 further includes fourth and fifth fluid channels 262, 264, which couple the outlets of the second and third pumps 250, 260 to reactor 270. For example... Figure 14 As shown, reactor 270 includes a top surface 272, a bottom surface 274, and an internal annular chamber 276 extending from the top surface 272 to the bottom surface 274. Reactor 270 also includes a central tube 275 having an open upper inlet 278 and an outlet 280. Reactor 270 may also include one or more upper outlets 282. Reactor 270 may be coupled to an energy source (not shown) configured to generate a vortex of swirling gas within the annular chamber 276. The energy source may include any suitable energy source, such as a pump, compressor, generator, etc. The swirling gas preferably flows from the bottom of reactor 270 around the central tube 275 to the top, causing nanofiber clusters and individual nanoparticles to move upwards from the bottom surface 275 toward the top surface 272.

[0134] In another embodiment, the generation of vortices does not require a separate energy source. In this embodiment, nanofiber clusters 290 and individual nanoparticles 292 enter reactor 270 through bottom inlets 284, 285, 286, and 287. Inlets 284, 285, 286, and 287 are inclined upwards to facilitate the movement of nanofibers and nanoparticles around a central tube 275. In a preferred embodiment, at least one or more of inlets 284, 285, 286, and 287 are inclined such that the nanofibers and nanoparticles are substantially tangential to the central tube 275 when they enter reactor 270. Once they enter an annular chamber 276, the velocity vectors (velocity and direction) of the nanofibers and nanoparticles generate vortices within reactor 270, causing them to swirl around the central tube 275 and rise upwards to the upper part of chamber 276. The swirling gas preferably flows from the bottom of reactor 270 around the central tube 275 to the top, causing the nanofiber clusters and individual nanoparticles to move upwards from the bottom surface 275 toward the top surface 272. Nanofibers 290 and nanoparticles 292 are blown from the bottom to the top of the reactor undisturbed. The vortex within chamber 276 can further break down (e.g., open, separate, and / or individualize) the nanofiber clusters 290 as they pass through reactor 270.

[0135] In some embodiments, reactor 270 may also be coupled to an energy source (not shown) configured to generate vortices of swirling gas within annular chamber 276. The energy source may include any suitable energy source, such as a pump, compressor, generator, etc.

[0136] System 100 may also include another pump or negative pressure source coupled to the upper outlet 282 (e.g., see...). Figure 14 The negative pressure draws the fibers out of outlet 282, causing fibers 290 to exit reactor 270. Since individual nanoparticles 292 are significantly lighter than the still-aggregated tangled nanofibers 290, these individual nanoparticles 292 are drawn into the upper inlet 278 of the central tube 275. Simultaneously, larger and heavier clusters of nanofibers 290 that have not yet been decomposed are drawn out through upper outlet 284. Upper outlet 284 can be coupled to other pumps (not shown) or to the first pump 240. In this way, the nanofiber clusters 290 are reintroduced into the process for further decomposition, thus forming a refeed system to further decompose the remaining nanofiber clusters.

[0137] The outlet 280 of the central tube 275 is coupled to the nozzle 220 (see...). Figure 9Individual nanoparticles 292 are drawn into nozzle 220, where they are dispersed onto the substrate surface or into the fiber stream (discussed below). Nozzle 220 may comprise any suitable nozzle known to those skilled in the art. In one embodiment, nozzle 220 has multiple outlets whose external dimensions are customized according to the dimensions (i.e., area) of the substrate beneath nozzle 220. Nozzle 220 disperses the nanoparticles onto the substrate at a rate driven by the pressure of the entire system.

[0138] In some embodiments, system 100 includes more than one nozzle coupled to outlet 280 of reactor 270. The nozzles may be arranged on the substrate in any suitable manner (e.g., side-by-side, in series, in parallel, etc.).

[0139] It should be recognized that pump 240 or pumps 250, 260 can directly feed the nanofiber / air mixture into nozzle 220 (i.e., bypassing reactor 270). In this embodiment, the pressure within the system is designed to generate sufficient kinetic energy to break down or open substantially all of the nanofibers into individual nanoparticles, thus eliminating the need for reactor 270 to separate nanoparticles from larger fiber clusters.

[0140] For reference Figure 15 Another embodiment of the fiberization system 320 will now be described. As shown, the fiberization system 320 includes a separator 325 for separating larger or larger clusters of nanofibers into smaller clusters that will pass through the system 320. A first ejector 326 is coupled to the outlet of the separator 325 for drawing nanofibers from the separator 325 into the system 320. An air compressor (not shown) is also coupled to the ejector 326 to provide motive fluid, as discussed above.

[0141] Similar to previous embodiments, the second and third ejectors 330, 340 are coupled to the outlet of the first ejector 326. Nanofibers are extracted from the first ejector 320 and pushed toward the surface of the T-shaped intersection 350 to break at least some of the nanofibers into smaller clusters or individual nanoparticles.

[0142] Each of the second and third ejectors 330, 340 has an outlet coupled to additional T-shaped intersections 360, 370. As before, the nanofibers are pushed towards the surfaces of the T-shaped intersections 360, 370 for further decomposition. The T-shaped intersections 360, 370 are each coupled to two fluid channels leading into the bottom 380 of the reactor. Therefore, the bottom 380 of the reactor has four separate inlets 382, ​​384, 386, 388 for the passage of the nanofibers. Each of these inlets is preferably inclined upwards and located at an opposite corner of the reactor. This allows the nanofibers to enter the vortex of the reactor and then vortex upwards to the upper part 390 of the reactor.

[0143] As previously referenced Figure 14 The reactor discussed comprises an annular chamber, wherein a central tube has an open upper end and a lower end coupled to a nozzle. Nanofibers, sufficiently decomposed into individual nanoparticles, flow through the open upper end and into the central tube for dispersion via the nozzle. Heavier clusters of nanoparticles that have not yet decomposed exit the reactor through one of four independent outlets 392, 394, 396, and 398. Ejectors 410 and 420 provide the power to extract the nanofibers from the reactor 400, as discussed above. Outlets 392 and 394 are each coupled to ejector 410 via a T-junction 412, and outlets 396 and 398 are each coupled to ejector 420 via a T-junction 422. In this configuration, the nanofibers flow from two channels into one channel as they pass through junctions 412 and 422.

[0144] Injectors 410 and 420 are each coupled to T-junctions 430 and 440, respectively. As previously discussed, nanofibers are pushed into T-junctions 430 and 440 to further break them down into individual nanoparticles. T-junctions 430 and 440 are then coupled to the bottom 380 of reactor 400 (via inlets 432, 434, 442, and 444). This allows the nanofibers to return to reactor 400 for further processing. This process is repeated continuously for each nanofiber cluster until it is completely broken down into nanoparticles and enters the nozzle through the central tube. As a final step, the individualized nanofibers are sprayed from the nozzle onto any substrate or mixed with any fiber spun stream. During this process, suction power reaches up to 20 psi and pressure reaches up to 100 psi.

[0145] In some embodiments, the fiberization system 150 may include a separate control system that monitors the nanofibers to determine when they break down into individual nanoparticles suitable for passage through a nozzle. The control system may, for example, simply monitor the pressure throughout the system to ensure sufficient pressure is applied to the nanofibers to break them down into nanoparticles. Alternatively, the control system may include various sensors arranged within the system to detect characteristics of the nanoparticles, such as weight or size. The sensors may be arranged, for example, within reactor 400, such that the control system can control various parameters of reactor 400, such as negative pressure applied to outlets 392, 394, 396, 398, the velocity of the vortex passing around the annular chamber, or the pressure applied to the central tube to draw the nanoparticles into the nozzle.

[0146] Figure 16A filter product 700 is shown, comprising a filter medium 710 including a porous membrane comprising fibers 722 and nanoparticles 720 dispersed in at least a portion of the filter medium 710. As shown, the filter medium 710 has a first upper surface 712 and a second lower surface 714. The nanoparticles are dispersed through the upper surface 712 such that they extend beyond the upper surface 712 and penetrate to a certain depth into the filter medium 710, as discussed above. The filter product 700 also includes a support layer 730, which can be any suitable support layer known in the art, such as a substantially rigid polymer providing support for the filter medium 710, or an open-pore membrane having multiple pores for gas or fluid to pass through (as discussed above).

[0147] Figure 17 Another filtration product 740 is shown, which includes a filter medium 710 comprising a porous membrane containing fibers 722 and nanoparticles 720 dispersed in a portion of the filter medium 710. In this embodiment, product 740 includes a loosely woven fabric layer 750 bonded to a support layer 730.

[0148] Figure 18 A dual-layer filtration product 760 is shown, comprising a first filter medium and second filter media 762, 764 bonded together. As shown, nanoparticles 720 are dispersed throughout a certain depth in each filter medium 762, 764. In this embodiment, the nanoparticles 720 are dispersed via the inner surfaces 766, 768 of the filter media 762, 764. In another embodiment (not shown), the nanoparticles are dispersed via the outer surfaces 770, 772 of the filter media 762, 764. In yet another embodiment, the nanoparticles 720 may be deposited on the inner surface 766 of medium 762 and the outer surface 772 of medium 764.

[0149] A more complete description of the filter media containing nanoparticles can be found in the co-assigned, co-pending U.S. Provisional Patent Application Serial Nos. 63 / 328,970, 63 / 328,959, 63 / 328,983, 63 / 328,998, 63 / 329,009, 63 / 329,018, 63 / 329,137, 63 / 329,146, 63 / 329,155, 63 / 329,158, 63 / 329,161, and 63 / 329,162, all of which were filed on April 8, 2022, the entire disclosure of which is incorporated herein by reference in its entirety for all purposes.

[0150] While the apparatus, system, and method have been described in detail herein with respect to certain preferred embodiments, many modifications and variations can be made therein by those skilled in the art. Therefore, the above description should not be construed as limiting, but rather as including such obvious variations as described above, and is limited only by the spirit and scope of the appended claims.

[0151] In some implementations, nanoparticles are dispersed between continuous fibers, such as spunbond fibers and meltblown fibers. The spunbond medium can be made of monocomponent or bicomponent fibers.

[0152] For example, in a first aspect, a first embodiment is a filter medium comprising a porous membrane and nanoparticles disposed within the porous membrane, the porous membrane comprising fibers and having an average flow pore size of less than about 10 micrometers.

[0153] The second implementation scheme is the first implementation scheme, and the fibers include short fibers.

[0154] The third implementation scheme is any combination of the first two implementation schemes, wherein the fiber is a wet-laid web fiber.

[0155] The fourth implementation scheme is any combination of the first three implementation schemes, wherein the fiber is a nonwoven fiber.

[0156] The fifth embodiment is any combination of the first four embodiments, wherein the short fibers have a length of about 2 mm to about 10 mm.

[0157] The sixth embodiment is any combination of the first five embodiments, wherein the fiber comprises polyolefins, polyesters, polyethylene (PE), polypropylene (PP), blends of PP and PE, PBT, PET, CoPET, PLA, PA, PHB, PVOH, polyamides, and combinations thereof.

[0158] The seventh embodiment is any combination of the first six embodiments, wherein the fiber includes polyester.

[0159] The eighth embodiment is any combination of the first seven embodiments, wherein the average pore size is less than about 5 micrometers.

[0160] The ninth embodiment is any combination of the first eight embodiments, wherein the average pore size is less than about 4 micrometers.

[0161] The tenth embodiment is any combination of the first nine embodiments, wherein the filter medium has a bubble point of about 5 micrometers to about 50 micrometers.

[0162] The eleventh implementation is any combination of the first ten implementations, wherein the filter medium has a bubble point of less than about 20 micrometers.

[0163] The twelfth embodiment is any combination of the first eleven embodiments, wherein the filter medium has a bubble point of less than about 10 micrometers.

[0164] The thirteenth implementation is any combination of the first twelve implementations, wherein the filter medium has a bubble point of approximately 5 micrometers.

[0165] The 14th embodiment is any combination of the first 13 embodiments, wherein the filter medium is configured to be used as a liquid filter.

[0166] The 56th embodiment is any combination of the first 14 embodiments, wherein the porous membrane has a thickness from the first surface to the second surface, and wherein the nanoparticles are arranged within the porous membrane at a thickness of at least 25% of the thickness from the first surface to the second surface.

[0167] The 16th embodiment is any combination of the first 15 embodiments, wherein the nanoparticles are arranged within the porous membrane at a thickness of at least 50% from the first surface to the second surface.

[0168] The 17th embodiment is any combination of the first 16 embodiments, wherein the fiber is a biological component fiber.

[0169] The 18th embodiment is any combination of the first 17 embodiments, wherein the nanoparticles are substantially uniformly dispersed throughout the porous membrane.

[0170] The 19th embodiment is any combination of the first 18 embodiments, wherein the nanoparticles are generated in the gas and dispersed through the first surface of the porous membrane.

[0171] The 20th embodiment is any combination of the first 19 embodiments and also includes an adhesive within the porous membrane that retains the nanoparticles within the porous membrane.

[0172] The 21st embodiment is any combination of the first 20 embodiments, wherein the nanoparticles are selected from carbon fiber, glass fiber, polypropylene fiber, nylon fiber, polylactide fiber, polyester fiber, fibrillated cellulose, polyethylene fiber, and combinations thereof.

[0173] In a second aspect, the first embodiment is a liquid filter comprising a porous membrane, the porous membrane comprising fibers and having an average pore size of less than about 10 micrometers, wherein the filter has a bubble point of about 5 to about 50 micrometers.

[0174] The second implementation scheme is the first implementation scheme, wherein the bubble point is less than about 20 micrometers.

[0175] The third implementation scheme is any combination of the first two implementation schemes, wherein the bubble point is less than about 10 micrometers.

[0176] The fourth implementation scheme is any combination of the first three implementation schemes, wherein the bubble point is approximately 5 micrometers.

[0177] The fifth embodiment is any combination of the first four embodiments, wherein the average pore size is less than about 5 micrometers.

[0178] The sixth embodiment is any combination of the first five embodiments, wherein the average pore size is less than about 4 micrometers.

[0179] The seventh embodiment is any combination of the first six embodiments, wherein the porous membrane comprises short fibers.

[0180] The eighth embodiment is any combination of the first seven embodiments, wherein the fiber comprises short fibers having a length of about 2 to about 10 mm.

[0181] The ninth embodiment is any combination of the first eight embodiments, wherein the short fibers comprise polyolefins, polyethylene (PE), polypropylene (PP), blends of PP and PE, PBT, PET, CoPET, PLA, PA, PHB, polyamides, and combinations thereof.

[0182] The 10th embodiment is any combination of the first nine embodiments and also includes nanoparticles arranged within the porous membrane, wherein at least one of the nanoparticles has a size of less than 1 micrometer.

[0183] The 11th embodiment is any combination of the first 10 embodiments, wherein the nanoparticles are generated in the gas and dispersed through the first surface of the porous membrane.

[0184] In a third aspect, the first embodiment is a method for manufacturing a filter medium, the method comprising providing a porous membrane comprising short fibers, and dispersing nanoparticles into a first surface of the porous membrane such that the nanoparticles penetrate at least the first surface, wherein the nanoparticles reduce the average flow pore size of the porous membrane to less than about 10 micrometers.

[0185] The second implementation scheme is the first implementation scheme, in which the nanoparticles reduce the average flow pore size to less than about 5 micrometers.

[0186] The third embodiment is any combination of the first two embodiments, wherein the nanoparticles reduce the average flow pore size to less than about 4 micrometers.

[0187] The fourth embodiment is any combination of the first three embodiments, wherein the nanoparticles reduce the average flow pore size to about 3 micrometers.

[0188] The fifth implementation scheme is any combination of the first four implementation schemes, and also includes generating short fibers through a wet web forming process.

[0189] The sixth implementation scheme is any combination of the first five implementation schemes, and also includes calendered short fibers and nanoparticles.

[0190] The seventh embodiment is any combination of the first six embodiments, and also includes spraying individual nanoparticles onto the first surface of the porous membrane.

[0191] The eighth embodiment is any combination of the first seven embodiments, and also includes applying suction to a second surface of the first layer opposite the first surface to draw individual nanoparticles through the first layer.

[0192] The ninth embodiment is any combination of the first eight embodiments and also includes applying an adhesive to fibers within the porous membrane.

[0193] The 10th embodiment is any combination of the first 9 embodiments, wherein the porous membrane has a bubble point of about 5 micrometers to about 50 micrometers.

[0194] The 11th embodiment is any combination of the first 10 embodiments, wherein the porous membrane has a bubble point of less than about 20 micrometers.

[0195] The 12th embodiment is any combination of the first 11 embodiments, wherein the porous membrane has a bubble point of less than about 10 micrometers.

[0196] The 13th embodiment is any combination of the first 12 embodiments, wherein the porous membrane has a bubble point of about 5 micrometers.

[0197] The 14th embodiment is a liquid filter produced by any one of the methods in the preceding 13 embodiments.

Claims

1. A filter medium, comprising: A porous membrane comprising fibers and having an average flow pore size of less than about 10 micrometers; as well as Nanoparticles arranged within the porous membrane.

2. The filter medium according to claim 1, wherein the fiber comprises short fibers.

3. The filter medium according to claim 2, wherein the fibers are combed.

4. The filter medium according to claim 1, wherein the fiber is a wet-laid fiber.

5. The filter medium according to claim 1, wherein the fiber is a nonwoven fiber.

6. The filter medium according to claim 1, wherein the fibers have a length of about 2 mm to about 10 mm.

7. The filter medium according to claim 1, wherein the fibers have a length of about 40 mm to about 100 mm.

8. The filter medium according to claim 1, wherein the fibers are continuous fibers.

9. The filter medium according to claim 8, wherein the fibers are spunbond.

10. The filter medium according to claim 8, wherein the fiber is melt-blown.

11. The filter medium according to claim 1, wherein the fiber comprises polyolefin, polyester, polyethylene (PE), polypropylene (PP), blends of PP and PE, PBT, PET, CoPET, PLA, PA, PHB, PVOH, polyamide, and combinations thereof.

12. The filter medium according to claim 1, wherein the fiber comprises polyester.

13. The filter medium according to claim 1, wherein the average pore size is less than about 5 micrometers.

14. The filter medium according to claim 1, wherein the average pore size is less than about 4 micrometers.

15. The filter medium according to claim 1, wherein the filter medium has a bubble point of about 5 micrometers to about 50 micrometers.

16. The filter medium according to claim 1, wherein the filter medium has a bubble point of less than about 20 micrometers.

17. The filter medium according to claim 1, wherein the filter medium has a bubble point of less than about 10 micrometers.

18. The filter medium according to claim 1, wherein the filter medium has a bubble point of about 5 micrometers.

19. The filter medium according to claim 1, wherein the filter medium is configured to function as a liquid filter.

20. The filter medium of claim 1, wherein the porous membrane has a thickness from a first surface to a second surface, wherein the nanoparticles are arranged within the porous membrane at a thickness of at least 25% of the thickness from the first surface to the second surface.

21. The filter medium of claim 16, wherein the nanoparticles are arranged within the porous membrane at a thickness of at least 50% from the first surface to the second surface.

22. The filter medium according to claim 1, wherein the fiber is a biological component fiber.

23. The filter medium according to claim 1, wherein the nanoparticles are substantially uniformly dispersed throughout the porous membrane.

24. The filter medium according to claim 1, wherein the nanoparticles are generated in the gas and dispersed through the first surface of the porous membrane.

25. The filter medium according to claim 1, further comprising an adhesive within the porous membrane, the adhesive retaining the nanoparticles within the porous membrane.

26. The filter medium according to claim 1, wherein the nanoparticles are selected from carbon fiber, glass fiber, polypropylene fiber, nylon fiber, polylactide fiber, polyester fiber, fibrillated cellulose, polyethylene fiber, and combinations thereof.

27. The filter medium of claim 1, wherein at least one of the nanoparticles has a size of less than about 20 micrometers.

28. The filter medium of claim 1, wherein at least one size of the nanoparticles is from about 1 micrometer to about 20 micrometers.

29. The filter medium according to claim 1, wherein at least one of the nanoparticles has a size of less than about 1 micrometer.

30. A liquid filter comprising the filter medium of claim 1.

31. A liquid filter, comprising: A porous membrane comprising fibers and having an average pore size of less than approximately 10 micrometers; and The filter described therein has a bubble point of about 5 micrometers to about 50 micrometers.

32. The liquid filter of claim 31, wherein the bubble point is less than about 20 micrometers.

33. The liquid filter of claim 31, wherein the bubble point is less than about 10 micrometers.

34. The liquid filter of claim 31, wherein the bubble point is about 5 micrometers.

35. The liquid filter of claim 31, wherein the average pore size is less than about 5 micrometers.

36. The liquid filter of claim 31, wherein the average pore size is less than about 4 micrometers.

37. The liquid filter of claim 31, wherein the porous membrane comprises short fibers.

38. The liquid filter of claim 31, wherein the fiber comprises short fibers having a length of about 2 mm to about 10 mm.

39. The liquid filter of claim 38, wherein the short fibers comprise polyolefins, polyethylene (PE), polypropylene (PP), blends of PP and PE, PBT, PET, CoPET, PLA, PA, PHB, polyamides, and combinations thereof.

40. The liquid filter of claim 37 further comprises nanoparticles disposed within the porous membrane.

41. The liquid filter of claim 40, wherein at least some of the nanoparticles are combined with at least some of the short fibers.

42. The liquid filter of claim 40, wherein the nanoparticles are generated in the gas and dispersed through the first surface of the porous membrane.

43. The liquid filter of claim 40, wherein at least one of the nanoparticles has a size of less than about 20 micrometers.

44. The liquid filter of claim 40, wherein at least one size of the nanoparticles is from about 1 micrometer to about 20 micrometers.

45. The liquid filter of claim 40, wherein at least one of the nanoparticles has a size of less than about 1 micrometer.

46. ​​The liquid filter of claim 31, further comprising a housing including an inlet for receiving liquid and an outlet for discharging liquid, wherein the filter medium is disposed within the housing between the inlet and the outlet.

47. The liquid filter of claim 46, wherein the housing comprises a cylinder.

48. The liquid filter of claim 46, wherein the housing comprises a bag.

49. A method for manufacturing a filter medium, the method comprising: Provide porous membranes containing short fibers; as well as Nanoparticles are dispersed into a first surface of the porous membrane such that the nanoparticles penetrate at least the first surface, wherein the nanoparticles reduce the average flow pore size of the porous membrane to less than about 10 micrometers.

50. The method of claim 49, wherein the nanoparticles reduce the average flow pore size to less than about 5 micrometers.

51. The method of claim 49, wherein the nanoparticles reduce the average flow pore size to less than about 4 micrometers.

52. The method of claim 49, wherein the nanoparticles reduce the average flow pore size to about 3 micrometers.

53. The method of claim 49 further comprises forming a web by a wet web forming process, wherein the web comprises short fibers.

54. The method of claim 53, further comprising thermally bonding the short fibers and the nanoparticles.

55. The method of claim 49, further comprising spraying individual nanoparticles onto a first surface of the porous membrane.

56. The method of claim 55, further comprising applying suction to a second surface of the first layer opposite the first surface to draw the individual nanoparticle through the first layer.

57. The method of claim 49, further comprising applying an adhesive to the fibers within the porous membrane.

58. The method of claim 49, wherein the porous membrane has a bubble point of about 5 micrometers to about 50 micrometers.

59. The method of claim 49, wherein the porous membrane has a bubble point of less than about 20 micrometers.

60. The method of claim 49, wherein the porous membrane has a bubble point of less than about 10 micrometers.

61. The method of claim 49, wherein the porous membrane has a bubble point of about 5 micrometers.

62. A liquid filter produced by the method of claim 49.

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