Multi-layer fiber composite filter media

Abstract

The composite media includes a laminate having 20 or more layers, each layer including a substrate having a first major surface and an opposite second major surface, and a fiber layer including polymer fibers having a diameter of 100 nm to 1.5 μm stacked on the first major surface of the substrate. Each fiber layer has an individual thickness of 5 μm to 100 μm, and each layer has an individual pore size of 0.1 μm to 10 μm. The filter can include a housing and the composite media described above disposed within the housing. The filter can be a syringe filter.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of U.S. Provisional Patent Application No. 63 / 292,724, filed December 22, 2021, the disclosure of which is incorporated herein by reference in its entirety. [Technical field]

[0002] The present disclosure relates to a filter medium containing fine fibers.The present disclosure further relates to a filter medium including multiple layers containing fine fibers. Summary of the Invention [Means for solving the problem]

[0003] The composite medium includes a laminate having 20 or more layers, each layer including a substrate having a first major surface and an opposing second major surface, and a fiber layer stacked on the first major surface of the substrate, the fiber layer including polymer fibers having a diameter between 100 nm and 1.5 μm. Each fiber layer individually has a thickness between 5 μm and 100 μm. Each layer individually has a P95 pore size between 0.1 μm and 10 μm. The substrate may be a nonwoven substrate. The substrate may be a membrane.

[0004] The laminate may include a layer having two or more fibrous layers. Each layer of the laminate may optionally include two or more fibrous layers. The laminate may include a layer with a second fibrous layer stacked on a second major surface of the substrate.

[0005] The P95 pore size of the fibrous layers may be 0.5 μm to 5.0 μm, 0.7 μm to 2.0 μm, or 0.8 μm to 1.5 μm. The pore sizes of the fibrous layers may form a pore size gradient across the laminate. The composite media may have an inlet side and an outlet side, and the pore size gradient may be from a maximum P95 pore size of 50 μm at the inlet side to a minimum P95 pore size of 0.1 μm at the outlet side.

[0006] The laminate may have a pore size of 0.01 μm to 2.5 μm.The laminate may include 100 to 3000, 300 to 2000, or 500 to 1000 layers.

[0007] The laminate may include a first fibrous layer having a first composition and a second fibrous layer having a second composition different from the first composition. The fibrous layers of the laminate may form a gradient of chemical composition throughout the laminate. Alternatively, each layer in the laminate may have the same composition and structure.

[0008] The stack may include a first plurality of layers having a first degree of compression and a second plurality of layers having a second degree of compression different from the first degree of compression, and the plurality of layers may have a gradient of compression across the stack.

[0009] The initial water flux of the composite medium is 150 mL / cm 2 / hour / kPa~300mL / cm 2 / time / kPa.

[0010] The surface area to volume ratio of the fiber layer is 1 μm -1 or more, and optionally 20 μm -1 It may be the following.

[0011] The filter may include a housing and a complex media disposed within the housing. The filter may be a syringe filter.

[0012] The filter housing may be configured to compress a first plurality of layers to a first degree and a second plurality of layers to a second degree, where the second degree of compression is different from the first degree of compression, and the plurality of layers may have a gradient of compression across the stack. [Brief description of the drawings]

[0013] [Figure 1A] FIG. 2 is a schematic diagram of a single layer in one embodiment. [Figure 1B]FIG. 13 is a schematic diagram of a single layer in another embodiment. [Diagram 2] FIG. 1B is a schematic diagram of a composite medium in one embodiment comprising a stack of twenty or more of the layers of FIG. 1A. [Diagram 3] 3 is a schematic cross-sectional view of a filter including the composite media of FIG. 2 in one embodiment. [Figure 4] FIG. 1 is a schematic cross-sectional view of a filter in one embodiment including a stack of multiple layers with varying degrees of compression. [Diagram 5] FIG. 2 is a schematic top view of a single layer in one embodiment. [Figure 6] FIG. 2 is a schematic top view of a single layer having two fine fiber layers in one embodiment. [Figure 7] FIG. 7 is a schematic diagram of an embodiment in which two layers of FIG. 6 are arranged in a stack. [Figure 8A-8D] 7A-7C are schematic top views of a stack of two of the layers of FIG. 6 in various arrangements. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] definition All scientific and technical terms used herein have meanings commonly used in the art unless otherwise specified. The definitions provided herein are intended to facilitate understanding of certain terms used frequently herein and are not intended to limit the scope of the present disclosure.

[0015] Unless otherwise specified, the terms "polymer" and "polymeric material" include, but are not limited to, organic homopolymers, copolymers (e.g., block, graft, random and alternating copolymers, etc.), terpolymers, and the like, as well as mixtures and modifications thereof. Furthermore, unless specifically limited, the term "polymer" is intended to include all possible geometric configurations of the material. These configurations include, but are not limited to, isotactic, syndiotactic, and atactic symmetries.

[0016] As used herein, "resin" or "resinous" refers to monomers, oligomers, and / or polymers, especially those capable of migrating to the surface of the fibrils during fiber formation.

[0017] In this disclosure, the term "aromatic ring" refers to a conjugated ring system of an organic compound. The aromatic ring may contain only carbon atoms or may contain one or more heteroatoms such as oxygen, nitrogen, or sulfur.

[0018] In this disclosure, the term "alkylated" is used to describe a compound in which a compound is reacted to replace a hydrogen atom or negative charge therewith with an alkyl group, thereby covalently bonding the alkyl group to the compound.

[0019] In this disclosure, the term "alkyl" is used to describe a monovalent radical of an alkane, including linear, branched, cyclic, and bicyclic alkyl groups, and combinations thereof, and includes both unsubstituted and substituted alkyl groups. Unless otherwise specified, alkyl groups typically contain 1 to 30 carbon atoms. In some embodiments, alkyl groups contain 1 to 20 carbon atoms, 1 to 10 carbon atoms, 1 to 6 carbon atoms, 1 to 4 carbon atoms, or 1 to 3 carbon atoms. Examples of alkyl groups include, but are not limited to, methyl, ethyl, n-propyl, n-butyl, n-pentyl, isobutyl, t-butyl, isopropyl, n-octyl, n-heptyl, ethylhexyl, cyclopentyl, cyclohexyl, cycloheptyl, and the like.

[0020] The term "fine fibers" is used herein to refer to fibers having an average fiber diameter of 10 μm or less, which typically means that a sample of multiple fibers of the present disclosure will have an average fiber diameter of less than 10 μm.

[0021] The term "fiber diameter" is used herein to refer to the average diameter of a fiber, with the average fiber diameter being indicated by the fiber diameter in a sample of multiple fibers. Fiber diameter can be measured using top-down SEM images. Samples may be sputter coated with a sputter coater with a mixture of gold and palladium, such as a 60:40 Au:Pd mixture. More accurate fiber diameter measurements can be obtained by measuring the fiber diameter at at least 30 locations in the sample. Software such as Trainable Weka Segmentation (ImageJ plugin) can be useful for analyzing fiber diameter.

[0022] The term "pore size" is used herein to refer to the average pore size of the stream.

[0023] As used herein, unless otherwise specified, pore sizes (e.g., P5, P50, and P95) are measured using capillary flow porometry. Capillary flow porometry can be performed using a continuous pressure scan mode. It can be useful to use silicone oil as the wetting liquid, with a surface tension of 20.1 dynes / cm and a wetting contact angle of 0. The sample may be tested first in the dry state, varying from low to high pressure, and then in the wet state, varying from low to high pressure again. Testing is typically performed at ambient temperature conditions (e.g., 20°C to 25°C). A large number of data points, e.g., 256 data points, can be collected over the range of the pressure scan for both the dry and wet curves. Typically, tortuosity and / or shape factors are not used (i.e., factors equal to 1 can be used for comparison with other test methods that use adjustment factors). As used herein, the value P(x) is the calculated pore size when the wet curve is equal to (100-x)% of the dry curve, as measured using the method described herein. Although a calculated value, it can be understood as representing the property that x% of the total flow rate through the layer passes through pores of that size or less. For example, P50 (mean pore size of flow) represents the property that the wet curve is equal to half the dry curve, and can be considered as the pore size such that 50% of the total flow rate through the layer passes through pores of that size or less. P95 represents the property that 95% of the total flow rate through the layer passes through pores of that size or less.

[0024] The average pore size (e.g., average maximum pore size) can be calculated by averaging at least three measurements (obtained from at least three different sample locations). Individual measurements of maximum pore size (sometimes referred to as P100) can be found at the bubble point, where the bubble point is found after fluid begins to pass through the sample and there is an increase of at least 1% for three consecutive measurements, and 256 data points are collected across the scan at a rate of about 17 data points per minute.

[0025] The acronym "SAVR" is used herein to represent the ratio of surface area to volume of a material. SAVR may be either measured or estimated. SAVR may be estimated as SAVR=(4*c) / df, where c is the solidity of the material (e.g., fiber layer) and df is the average fiber diameter of the layer. SAVR may also be calculated as SAVR=(fiber length*fiber circumference) / layer volume. SAVR is typically calculated for a specific area of ​​material, such as a 1 inch (25 mm) diameter die cut piece of material.

[0026] As used herein, the term "substantially" has the same meaning as "significantly" and can be understood as modifying the following term with "at least about 90%", "at least about 95%", or "at least about 98%". As used herein, the term "substantially not" has the same meaning as "not significantly" and can be understood as the opposite of "substantially", i.e., modifying the following term with "25% or less", "10% or less", "5% or less", or "2% or less".

[0027] As used herein, the term "about" is used in conjunction with numerical values ​​to include normal variations in measurement as would be expected by one of ordinary skill in the art, and is understood to have the same meaning as "approximately," and encompasses a typical range of error, such as ±5% of the stated value.

[0028] Terms such as "a," "an," and "the" are not intended to refer to only a single thing or thing, but include the entire collection, specific instances of which may be used for illustration.

[0029] The terms "a," "an," and "the" are used synonymously with the term "at least one." The phrases "at least one of" and "including at least one of," followed by a list, refer to any one of the items in that list, and any combination of two or more items in that list.

[0030] As used herein, the term "or" is generally used in its ordinary sense, including "and / or," unless otherwise clear from the context. The term "and / or" means one or all of the listed elements or a combination of any two or more of the listed elements.

[0031] The recitation of numerical ranges by endpoints includes all numbers subsumed within that range (e.g., 1 to 5 includes 1, 1.5, 2, 2.75, 3, 3.80, 4, 5, etc.; or up to 10 includes 10, 9.4, 7.6, 5, 4.3, 2.9, 1.62, 0.3, etc.). When a range of values ​​is "up to" or "at least" a particular value, then that value is included in that range.

[0032] As used herein, "having," "including," "comprising," and the like are used in their open-ended sense and generally mean "including, but not limited to." "Consisting essentially of," "consisting of," and the like are understood to be encompassed by "comprising," "including," and the like. As used herein, "consisting essentially of," when referring to a composition, article, method, and the like, means that the components of the composition, article, method, and the like are limited to the recited components and any other components that do not materially affect one or more basic and novel characteristics of the composition, article, method, and the like.

[0033] The words "preferred" and "preferably" refer to embodiments that may provide certain benefits, under particular circumstances. However, other embodiments may also be preferred, under the same or other circumstances. Furthermore, the recitation of one or more preferred embodiments does not imply that other embodiments are not useful, and is not intended to exclude other embodiments from the scope of the present disclosure, including the claims.

[0034] Any directions referred to herein, such as "up," "down," "left," "right," "upper," "lower," and other directions and orientations, are described herein with reference to the drawings for clarity and are not intended to limit the actual device or system or the use of the device or system. The devices or systems described herein can be used in multiple directions and orientations.

[0035] The present disclosure relates to a filter medium containing fine fibers.The present disclosure further relates to a filter medium including multiple layers containing fine fibers.

[0036] In one embodiment, the composite media includes a laminate including layers, each layer including a substrate having a first major surface and an opposing second major surface, and a fiber layer stacked on the first major surface of the substrate. The fiber layer includes polymer fibers. The fibers may be microfibers or nanofibers. The fibers may have a diameter between 100 nm and 1.5 μm. The fiber layer may have a thickness between 5 μm and 100 μm. The layers may have a P95 pore size between 0.1 μm and 10 μm.

[0037] In one embodiment, the composite media (e.g., the fiber layer of the composite media) has a high surface area to volume ratio ("SAVR"). The composite media can be used in any filter that can benefit from a layered microfiber structure and a high SAVR. In some examples, the composite media is used in a syringe filter.

[0038] The number of layers in the stack can be varied to add depth to the composite media and, therefore, different properties. Composite media can have different stack layers. Composite media can include multiple stacks with different properties. Composite media can provide one or more different gradients, such as, for example, a gradient of pore size, or a gradient of chemical composition and chemical functionality.

[0039] The number of layers in the laminate may be 2 or more, 5 or more, 10 or more, 20 or more, 50 or more, 100 or more, 200 or more, 300 or more, or 500 or more. The laminate may include 3000 or less, 2500 or less, 2000 or less, 1500 or less, or 1000 or less layers. The number of layers in the laminate may be 100 to 3000, 300 to 2000, or 500 to 1000.

[0040] Each layer of the stack has at least one substrate and at least one fiber layer. Typically, each layer includes only one substrate. The layer may include a single substrate and a single fiber layer stacked on the substrate. Referring now to FIG. 1A, a schematic diagram of a single layer 10 including a substrate 21 and a fiber layer 22 stacked on the substrate 21 is shown. A schematic diagram of a composite media 50 including a stack 60 of 20 or more layers 10 is shown in FIG. 2.

[0041] In some embodiments, one or more of the layers may include a single substrate and two or more fiber layers stacked on the substrate. For example, one or more of the layers may include a single substrate, one fiber layer stacked on a first major surface of the substrate, and another fiber layer stacked on a second major surface of the substrate. Referring now to FIG. 1B, a schematic diagram of a single layer 12 is shown, including a substrate 21, a first fiber layer 22A stacked on a first major surface of the substrate 21, and a second fiber layer 22B stacked on a second major surface of the substrate 21.

[0042] The layer may also include a first fibrous layer stacked on the substrate and one or more additional fibrous layers stacked on the first fibrous layer. Such fibrous layers can be distinguished from one another, for example, by their structure or chemical composition.

[0043] In one embodiment, the fibrous layer comprises polymeric fibers, i.e., the fibers comprise or consist of a polymeric material. In some embodiments, the fibrous layer does not comprise glass fibers. In some embodiments, the polymeric material is selected to be suitable for electrospinning deposition. The composition of the polymeric fibers may also be selected to impart desirable properties, such as chemical affinity, to the fibrous layer based on the intended use of the composite medium.

[0044] The diameter of the fibers may be 100 nm or more, 200 nm or more, 300 nm or more, 400 nm or more, or 500 nm or more. The diameter of the fibers may be 3 μm or less, 2 μm or less, 1.5 μm or less, 1.2 μm or less, or 1.0 μm or less. In some embodiments, the fibers have a diameter in the range of 100 nm to 1.5 μm, 300 nm to 1.2 μm, or 500 nm to 1.0 μm. In some cases, the fibers may be characterized as fine fibers. The fiber diameter of each layer is not necessarily the same throughout the stack. The fiber diameter of each layer may be selected individually. The layers in the stack may form a fiber diameter gradient throughout the stack.

[0045] The thickness of each fiber layer of the laminate may be individually 5 μm or more, 10 μm or more, 25 μm or more, or 50 μm or more. The thickness of each fiber layer may be individually 100 μm or less, 80 μm or less, or 60 μm or less. The thickness of the fiber layer may be in the range of 5 μm to 100 μm, 10 μm to 80 μm, or 20 μm to 60 μm. The thickness of each fiber layer is not necessarily the same throughout the laminate. Different fiber layers in the laminate may have different thicknesses. The fiber layers in the laminate may form a fiber layer thickness gradient throughout the laminate.

[0046] The thickness of the substrate may be 50 μm or more, 100 μm or more, or 500 μm or more. The thickness of the substrate may be 1000 μm or less, 750 μm or less, or 500 μm or less. The thickness of the substrate may be 50 μm to 1000 μm, or 100 μm to 500 μm. The total thickness of the layer (combination of substrate and fibrous layer) may be 55 μm to 1100 μm, or 150 μm to 600 μm. The filter media may include a stack of 100 to 3000 layers, so that the total thickness of the filter media may be 5500 μm (5.5 mm) or more.

[0047] The P95 pore size of each layer may be individually 0.05 μm or more, 0.1 μm or more, 0.3 μm or more, 0.5 μm or more, 0.7 μm or more, or 1.0 μm or more. The P95 pore size of each layer may be individually 20 μm or less, 10 μm or less, 7.5 μm or less, 5.0 μm or less, 3.0 μm or less, 2.0 μm or less, or 1.5 μm or less. The P95 pore size of a layer may be in the range of 0.1 μm to 10 μm, 0.5 μm to 5.0 μm, 0.7 μm to 2.0 μm, 0.8 μm to 1.5 μm, or 1.0 μm to 1.5 μm. The pore size of each layer need not necessarily be the same throughout the laminate. Different layers in the laminate may have different pore sizes. The layers in the laminate may form a gradient of layer pore sizes throughout the laminate. In one embodiment, the composite media has a high SAVR. The SAVR of the fiber layer is 1 μm -1 More than 2μm -1 or more than 5μm -1 The SAVR of the fiber layer may be 20 μm or more. -1 Less than or equal to 15μm -1 The SAVR of the fiber layer may be less than 1 μm. -1 ~20μm -1 , or 2 μm -1 ~15μm -1 may be in the range.

[0048] The substrate can be made of any suitable material. In some embodiments, the substrate is a nonwoven substrate. In some embodiments, the substrate comprises a membrane.

[0049] The P95 pore size of the entire laminate may be 0.01 μm or more, 0.05 μm or more, 0.1 μm or more, 0.3 μm or more, 0.5 μm or more, 0.75 μm or more, or 1.0 μm or more. The P95 pore size of the laminate may be 2.5 μm or less, 2.2 μm or less, 2.0 μm or less, 1.75 μm or less, 1.5 μm or less, or 1.0 μm or less. The P95 pore size of the laminate may be 0.01 μm to 2.5 μm, 0.1 μm to 2.0 μm, or 0.5 μm to 1.5 μm.

[0050] In one embodiment, the initial water flux of the composite media is 100 mL / cm 2 / hour / kPa or more, 120mL / cm 2 / hour / kPa or more, 150mL / cm 2 / hour / kPa or more, 175mL / cm 2 / hour / kPa or more, or 200mL / cm 2 / hr / kPa or more. The initial water flux is 350mL / cm 2 / hour / kPa or less, 300mL / cm 2 / hour / kPa or less, or 250mL / cm 2 / hour / kPa or less. Water flux is measured by applying water at 25°C and 1 bar to the composite medium and measuring the flow rate with a flow meter. Values ​​measured include water pressure, water temperature, and volumetric flow rate.

[0051] Any suitable polymer or combination of polymers can be used to prepare the polymer fibers of the fibrous layer. The composition of the fibrous layer may be selected individually. The material of a single fiber may be homogenous throughout the fiber (e.g., a polymer, copolymer, or blend of multiple polymers) or may include a core-sheath structure, where the core has a different composition than the sheath. Suitable polymer materials are described, for example, in WO 2013 / 043987, filed September 21, 2012, and WO 2014 / 164130, filed March 5, 2014, both of which are incorporated herein by reference in their entirety.

[0052] In some embodiments, the polymer fibers are formed by mixing or blending a polymeric material (e.g., a fiber-forming polymer) with a resinous aldehyde composition. In a particular embodiment, the aldehyde composition is a melamine-aldehyde composition. When formed into a fiber, the mixture or blend of the fiber-forming polymeric material and the resinous aldehyde composition in the appropriate ratio can form at least two (e.g., concentric or coaxial) phases. The first phase is an inner core comprising the fiber-forming polymeric material. The core is surrounded by a second phase (coating) comprising the resinous aldehyde composition. A proportion of the resinous aldehyde composition may crosslink with adjacent polymer chains present in the core. A transition layer or transition phase comprising a mixture or blend of the polymeric material and the resinous aldehyde composition may be formed between the core and the coating. The weight ratio of the resinous aldehyde composition to the polymer may be 20 parts by weight or more of the resinous aldehyde composition per 100 parts by weight of the polymer. The fiber-forming polymeric material may also contain reactive groups, such as functional groups (eg, active hydrogen groups) that are capable of crosslinking with the alkoxy groups of the resinous aldehyde composition.

[0053] The term "fiber-forming polymer" (eg, homopolymer or copolymer) is used to refer to a polymer that is capable of forming fine fibers without reactive additives.

[0054] The fiber-forming polymeric material and the resinous aldehyde composition can be combined in the form of a solution or melt. In certain embodiments, the polymeric fibers are electrospun from a solution or dispersion. Thus, the polymeric material and the resinous aldehyde (e.g., melamine-aldehyde) composition can be dispersed or dissolved in at least one common solvent or solvent mixture suitable for electrospinning.

[0055] Suitable resinous aldehyde compositions contain two or more alkoxy groups per molecule that can crosslink the polymers used to make the microfibers described herein. Exemplary resinous aldehyde compositions useful as crosslinkers include the condensation products of urea and aldehydes, phenols and aldehydes, or melamine and aldehydes. One useful class of crosslinked resins includes resins based on nitrogen compounds such as melamine, urea, benzoguanamine, glycoluril, and other similar resins made by reacting aldehydes with nitrogen compounds.

[0056] Useful resinous aldehyde compositions (e.g., melamine-aldehyde compositions) include highly methylated melamine, partially methylated melamine, methylated high imino melamine, highly alkylated mixed ether melamine, highly alkylated carboxylated high imino mixed ether melamine, highly n-butylated melamine, n-butylated high imino and partially n-butylated melamine, partially iso-butylated melamine, partially n-butylated urea, partially iso-butylated urea, glycoluril, highly alkylated mixed ether melamine-formaldehyde, highly alkylated mixed ether carboxylated melamine resins, hexabutoxide ... methoxymethyl melamine, butoxymethyl melamine, highly alkylated mixed ether melamine, methoxymethyl methylol melamine, highly methylated melamine resins, melamine-formaldehyde resins co-etherified with methanol and n-butoxyethanol / n-butanol blends, melamine-formaldehyde resins co-etherified with methanol and n-butanol in n-butanol, butylated melamine-formaldehyde resins dissolved in blends of n-butanol and butyl glycol, partially n-butylated melamine, highly methylated melamine resins with high solids, Allnex Examples of suitable resinous aldehyde compositions include those sold under the trade name CYMEL available from BASF AG (Ludwigshafen, Germany), those sold under the trade name LUWIPAL available from BASF AG (Ludwigshafen, Germany), and those sold under the trade names RESIMENE, MAPRENAL, and MADURIT available from Prefere Resins Holding GmbH (Erkner, Germany), and mixtures thereof. Various combinations of resinous aldehyde compositions can be used as desired. The term "high" in relation to the degree of substitution (e.g., "highly alkylated," "highly methylated," etc.) is understood to mean 50% or more. That is, 50% or more of the available substitution sites are substituted.

[0057] Preferred fiber-forming polymeric materials contain one or more active hydrogen groups capable of reacting with and crosslinking to the resinous aldehyde composition. Active hydrogen groups include, but are not limited to, thiol (-SH), hydroxyl (-OH), carboxylate (-COH), amide (-C(O)-NH- or C(O)-NH 2) , amino (-NH2), or imino (-NH-), and anhydride (-COO)2 R groups (upon hydrolysis). Polymeric materials suitable for use in the polymeric compositions of the present disclosure include both addition and condensation polymeric materials having active hydrogens. Suitable examples include poly(meth)acrylic acid, polyamides, cellulose ethers and esters, poly(maleic anhydride), polyamines such as chitosan, and mixtures, blends, alloys, and block, graft, or random copolymers thereof. Preferred materials within these general categories include poly(vinyl alcohol) of various degrees of hydrolysis (e.g., 87% to 99.5%) in crosslinked and non-crosslinked forms. Other preferred examples of useful polymeric materials include cellulose derivatives selected from the group consisting of ethyl cellulose, hydroxyl ethyl cellulose, cellulose acetate, cellulose acetate butyrate, cellulose acetate propionate, cellulose acetate phthalate, and mixtures thereof; poly(meth)acrylic acid homopolymers and copolymers, such as styrene-(meth)acrylic acid copolymers and ethylene-(meth)acrylic acid copolymers; polyvinyl alcohol homopolymers or copolymers, such as polyvinyl butyral and ethylene-vinyl alcohol copolymers; poly(maleic anhydride) homopolymers or copolymers, such as styrene-maleic anhydride copolymers; and polyurethanes. As used herein, "poly(meth)acrylic acid" refers to poly(acrylic acid) and poly(methacrylic acid) polymers.

[0058] Many types of polyamides are also useful as polymeric materials in the fibers of the present disclosure. One useful class of polyamide condensation polymers is nylon materials. The term "nylon" is a general term for all long-chain synthetic polyamides. Nylon nomenclature generally includes a series of numbers, such as nylon-6,6 (the first number indicates the C6 diamine and the second number indicates the C6 diacid compound), indicating that the starting materials are C6 diamine and C6 diacid. Another nylon can be made by polycondensing ε-caprolactam in the presence of a small amount of water. This reaction forms nylon-6 (made from a cyclic lactam also known as ε-aminocaproic acid), which is a linear polyamide. Additionally, nylon copolymers are also contemplated. Exemplary nylon materials include nylon-6, nylon-6,6, nylon-6,10, mixtures or copolymers thereof.

[0059] Copolymers can be made by combining various diamine compounds, various diacid compounds, and various cyclic lactam structures in a reaction mixture, then forming a nylon that contains the monomeric materials randomly arranged in a polyamide structure. For example, a nylon-6,6-6,10 material is a nylon made from hexamethylenediamine and a blend of C6 and C10 diacids. Nylon-6-6,6-6,10 is a nylon made by copolymerization of ε-aminocaproic acid, hexamethylenediamine diacid, and a blend of C6 and C10 diacid materials. As used herein, the term "copolymer" includes polymers made from two or more different monomers, including terpolymers, etc.

[0060] Block copolymers are also useful as the polymeric material in the fibers of the present disclosure. When electrospinning fibers with such copolymers, the choice of solvent or solvent mixture is important. The solvent or solvent mixture selected is chosen so that both blocks are soluble in the solvent. Examples of useful block copolymers include PEBAX ε-caprolactam-b-ethylene oxide available from Arkema Inc. (Philadelphia, PA), and polyurethanes of ethylene oxide and isocyanate.

[0061] Addition polymers such as polyvinyl alcohol and amorphous addition polymers such as poly(acrylonitrile) copolymers with acrylic acid are also useful. These can be dissolved or dispersed in a variety of solvents and solvent mixtures at low pressure and temperature, and thus can be solution spun relatively easily. For example, poly(vinyl alcohol) having a degree of hydrolysis of 87-99.9+% can be used as the polymeric material in the fibers of the present disclosure.

[0062] Preferred polymers include polyamides (especially nylons), polyesteramides, polyvinyl alcohol, ethylene-co-vinyl alcohol polymers, polyvinyl butyral, and poly(maleic anhydride). Preferred active hydrogen groups include hydroxy-1, amino, and amide groups. Various combinations of polymeric materials can be used as desired.

[0063] In some embodiments, the polymer fiber can be formed from a fiber-forming polymeric material and at least two reactive additives that can react with each other, for example, during the fiber-forming process or post-treatment process. The at least two reactive additives are optionally also reacted with the fiber-forming polymer. Typically, the amount of the one or more reactive additives to the one or more fiber-forming polymers is 0.5 parts by weight or more, 1 part by weight or more, 5 parts by weight or more, 10 parts by weight or more, or 20 parts by weight or more of the reactive additive per 100 parts by weight of the fiber-forming polymer. Typically, the amount of the one or more reactive additives to the one or more fiber-forming polymers is 200 parts by weight or less, or 50 parts by weight or less of the reactive additive per 100 parts by weight of the fiber-forming polymer.

[0064] The term "reactive additive" refers to monomers, oligomers, and / or polymers that contain functional groups capable of reacting with functional groups of other reactive additives and, optionally, with fiber-forming polymers.

[0065] The weight average molecular weight of the reactive additive may be less than 3000 Daltons. Preferred reactive additives are substantially non-volatile at room temperature and pressure. The reactive additive is selected to have a preferred solubility in the solvent selected for the polymeric material for processing such as electrospinning. The reactive additive may be a surface transfer agent that can migrate to the surface of the microfiber, usually during fiber formation. Exemplary suitable reactive additives are classified by functionality as follows: alkoxy-functional, hydroxyl-functional, acid-functional, glycidyl ether-functional, isocyanate-functional, amine-functional, and dichloro-functional. Various reactivity combinations (e.g., combinations of materials that are reactive with each other) can be used in making the microfibers of the present disclosure.

[0066] Suitable alkoxy-functional reactive additives include the exemplary resinous aldehyde compositions (eg, melamine-aldehyde compositions) described above.

[0067] Hydroxyl-functional reactive additives include bisphenol A; bisphenol AF; 4,4(1,4-phenylenediisopropylidene)bisphenol (PDPBPA); 4,4'(1-phenylethylidene)bisphenol (PEDBPA); hydroxyl-containing antioxidants commonly used in polymer processing, such as hindered aromatic phenols, such as those available under the trade names HOSTANOX O3 (Clariant), IRGANOX, etc.; fluorinated diols, such as POLYFOX reactive polymer intermediates from Omnova Chemicals; hydroxyl-containing compounds available under the trade names FOMBLIN PFPE FUNCTIONAL and FLUOROLINK from Solvay; aliphatic polycarbonate diols (such as those available under the trade name M112 from Perstop); phenoxy resins; phenolic resins; novolac resins; resorcinol; and polyols. When polyols are used, such polyols preferably contain at least two hydroxyl groups, and often up to 20 hydroxyl groups per polyol molecule. Hydroxyl-functional reactive additives include hydroxyl-functional unsaturated monomers such as (meth)acrylated pentaerythritol derivatives, (meth)acrylated glycerol, (meth)acrylated trimethylolpropane, (meth)acrylated DGEBA, unsaturated polyesters, hydroxyethyl methacrylate, hydroxyalkyl (meth)acrylate, allyl alcohol propoxylates, etc.; allyl ethers and esters of polyhydric alcohols such as trimethylolpropane (e.g., 1,1,1-trimethylolpropane) or pentaerythritol or allyl ethers of glycerol, erythritol, threitol, pentaerythritol, sorbitol, etc. Hydroxyl-functional reactive additives include cyclohexane dimethanol (e.g., diol UNOXOL available from Dow) or its ethoxylates, ethoxylated or propoxylated polyhydric alcohols (e.g., those available from Perstrop under the trade names BOLTRON polyols and ethoxylated pentaerythritol). These can include heterocyclic-based polyols.These can include copolymers of unsaturated aromatic monomers, such as styrene, and hydroxyl-containing unsaturated monomers, such as styrene-allyl alcohol copolymers available from Lyondell Corp. under the tradename SAA.

[0068] Hydroxyl-functional reactive additives include polymers containing hydroxyl groups, such as polyvinyl alcohol; ethylene vinyl alcohol, polyvinyl butyral, and polymers and copolymers containing hydroxyl groups, such as cellulose acetate, cellulose acetate butyrate, cellulose acetate propionate, and the like.

[0069] Acid-functional reactive additives include diacids, triacids, etc. These are typically carboxylic acids such as glutaric acid, succinic acid, adipic acid, malonic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, undecane diacid, dodecane diacid, phthalic acid, terephthalic acid, isophthalic acid, maleic acid, fumaric acid, glutaconic acid, traumatic acid, muconic acid, citric acid, ascorbic acid, dimethylolpropionic acid, etc.; fluorinated acids such as acid-containing compounds such as those available from Solvay under the tradenames FOMBLIN PFPE FUNCTIONAL and FLUOROLINK; polycarboxylic acids such as polyacrylic acid, styrene acrylic acid, polymethacrylic acid, styrene methacrylic acid, etc. Acid-functional reactive additives also include acyl halides such as adipoyl chloride. Acid-functional reactive additives may include weakly acidic oligomers or polymers. Examples include copolymers of (meth)acrylic acid (i.e. acrylic acid or methacrylic acid) with other unsaturated monomers such as styrene, copolymers of maleic acid or anhydride with other unsaturated monomers such as styrene (e.g. styrene-maleic anhydride copolymers), graft polymers in which the grafted group is a carboxylic acid or its anhydride, polymers containing phosphoric acid and its esters (e.g. additive available under the trade name ADDITOL XL-180 from Allnex GmbH), and unsaturated polycarboxylic acid resins characterized by dual functionality (e.g. available under the trade name SARBOX SB500E 50 from Sartomer).

[0070] Glycidyl ether functional reactive additives include diglycidyl ether-containing additives such as trimethylolpropane triglycidyl ether, and epoxy resins or low molecular weight reactive epoxy resins or resins sold under the diluent. Representative examples include epoxy resins, modified epoxy resins, brominated epoxy resins, and epoxy reactive diluents sold under the trade name DER by Dow Chemicals. These include bisphenol A diglycidyl ether, bisphenol A / F diglycidyl ether, bisphenol F diglycidyl ether, and modified bisphenol A diglycidyl ether, modified bisphenol A / F diglycidyl ether, modified bisphenol F diglycidyl ether, and the like. Other examples include epoxy novolac resins sold under the trade name DEN by Dow Chemicals, and epoxy resins such as those sold by Momentive. These include epoxy resins, and epoxy multifunctional resins, epoxy novolac resins, and epoxy polyacrylate resins sold under the trade name EPON, epoxy functional modifiers sold under the trade name HELOXY, and cycloaliphatic epoxy resins sold under the trade name EPO-NEX.

[0071] Isocyanate-functional reactive additives include aliphatic and aromatic polyisocyanates (e.g., triphenylmethane triisocyanate), preferably aromatic and aliphatic blocked polyisocyanates, such as those sold by Bayer under the trade names DESMODUR BL, BAYHYDUR BL, EVONIK, and VESTANAT.

[0072] Amine-functional reactive additives include polyethyleneimine, chitosan, lysine, polylysine, amino acids, and amines such as phenylenediamine (para, ortho, meta), dimethyl 4-phenylenediamine, triethylenetetramine, trimethylolpropane tris(poly(propylene glycol)amine terminated) ether, etc. Amine-functional reactive additives also include aliphatic and aromatic polyurethanes, fluorinated polyurethanes (prepolymer, oligomeric and polymeric).

[0073] An example of a dichloro-functional reactive additive is dichlorodiphenylsulfone.

[0074] In some embodiments, the individual fiber layers include variations in the structure, chemical composition, or properties of the fibers within those individual fiber layers. Characteristics that can be varied include, for example, fiber diameter, pore size, solidity, and chemical composition of the fibers. Variations in any one characteristic (e.g., fiber diameter) may be combined with variations in another characteristic (e.g., chemical composition). For example, a fiber layer may include first fibers having a first composition and second fibers having a second composition different from the first composition. The fiber diameters of the first and second fibers may be different.

[0075] In one embodiment, the fibers of the fibrous layer include a variation in fiber diameter. That is, the fibrous layer includes fibers having a first fiber diameter and fibers having a second fiber diameter. The fibrous layer may further include fibers having a third, fourth, and subsequent fiber diameters. The fibrous layer may include a mixture of fibers having different fiber diameters. In some embodiments, the fibrous layer includes a gradient of fiber diameters.

[0076] In one embodiment, the fibers of the fiber layer include a variation in chemical composition. That is, the fiber layer includes fibers having a first chemical composition and fibers having a second chemical composition. The fiber layer may further include fibers having a third, fourth, and subsequent chemical compositions. The fiber layer may include a mixture of fibers having different chemical compositions. In some embodiments, the fiber layer includes a gradient of chemical composition. Materials for functionalized or chemical filtration may include fibers made from polymers with selected functional groups or with other materials such as activated carbon or other adsorbents or absorbents included with the polymeric material. The fiber layer may include a mixture of fibers with different properties due to the different chemical compositions of the fibers.

[0077] In some embodiments, the individual fiber layers include variations in the structure, chemical composition, or properties of the fibers within those individual fiber layers. Characteristics that can be varied include, for example, fiber diameter, pore size, solidity, and chemical composition of the fibers. Variations in any one characteristic (e.g., fiber diameter) may be combined with variations in another characteristic (e.g., chemical composition). For example, a fiber layer may include first fibers having a first composition and second fibers having a second composition different from the first composition. The fiber diameters of the first and second fibers may be different.

[0078] In some embodiments, the variation of one or more characteristics within the fiber layer is arranged in a contiguous configuration. FIG. 5 is a schematic top view of a single layer 110 having a homogenous fiber layer 122. FIG. 6 is a schematic top view of a single layer 111 having a first type of fiber layer 122A and a second type of fiber layer 122B adjacent to each other. The first type of fiber layer 122A and the second type of fiber layer 122B together form a fiber layer. The first type of fiber layer 122A and the second type of fiber layer 122B may be arranged in a pattern or randomly distributed in the layer 111. The first type of fiber layer 122A and the second type of fiber layer 122B may be equal parts of the layer 111 or one type may be a larger part than the other. The fine fiber layer, including the first type of fiber layer 122A and the second type of fiber layer 122B, may be sandwiched between two substrate layers, thereby forming a substrate-fine fiber layer-fine fiber layer-substrate ("S-FF-FF-S") configuration.

[0079] As shown in FIG. 7, two or more layers 111 may be stacked together. The layers may be oriented such that the first type of fiber layer 122A and the second type of fiber layer 122B are not aligned. This results in an area where the first type of fiber layer 122A overlaps with the first type of fiber layer 122A of another layer to form an area 122AA, an area where the first type of fiber layer 122A overlaps with the second type of fiber layer 122B of another layer to form an area 122AB, and an area where the second type of fiber layer 122B overlaps with the second type of fiber layer 122B of another layer to form an area 122BB. FIGS. 8A-8D show several embodiments in which the size (area) of the areas 122AA, 122AB, and 122BB is changed by changing the orientation of the layers by an angle α.

[0080] The first type of fiber layer 122A and the second type of fiber layer 122B may differ in solidity, fiber size, pore size, chemical composition, or other properties. In one exemplary embodiment, the fine fiber layer includes a first type of fiber layer 122A and a second type of fiber layer 122B having different solidities. The fine fiber layers are arranged in an S-FF-FF-S configuration. In the area where the two different solidities overlap, the solidity of the composite layer is dominated by the high solidity portion, but has a theoretically lower differential pressure than the area where the two high solidity portion layers overlap. Multiple such layers with different angle α orientations can be stacked to create a composite medium with a gradient structure. Such an arrangement can provide the ability to capture smaller particle sizes at higher positions in the stack, thereby increasing the particle capture capacity (DHC) and life of the filter. Such an arrangement can also improve flow control within this configuration by increasing the residence time of the fluid being filtered.

[0081] In one embodiment, the composite media is included in a filter. Such a filter may include a housing and the composite media disposed within the housing. Referring now to FIG. 3, a schematic diagram of a filter 1 is shown including a housing 3 and a composite media 50 disposed therein. The filter housing defines an inlet 31 and an outlet 32. The composite media 50 may be oriented within the filter housing 3 as shown, either with the fiber layer 22 oriented toward the inlet 31 and the substrate 21 oriented toward the outlet, or conversely, with the fiber layer 22 oriented toward the outlet 32 ​​and the substrate 21 oriented toward the inlet 31. In some instances, some layers are oriented in one direction (e.g., the fiber layer 22 oriented toward the inlet 31) and other layers are oriented in another direction (e.g., the substrate 21 oriented toward the inlet 31). Optionally, additional layers may be included. Any suitable filter housing may be used. The composite media may be suitable for use in filtering a variety of liquids, such as aqueous or non-aqueous liquids. In some embodiments, the filter is a syringe filter. A typical syringe filter is a small disk-like filter that can be attached to the end of a syringe, for example, by a LUER-LOK connection. In some embodiments, the filter is a 25 mm or 47 mm inner diameter syringe filter. In some preferred embodiments, the filter is sterilizable, for example, by gamma radiation.

[0082] In some embodiments, the composite media includes variations in the structure, chemical composition, or properties of the layers throughout the stack. In some embodiments, these variations form a gradient in the stack. Characteristics that can vary include, for example, fiber diameter, pore size, thickness of the fiber layers, chemical composition of the fibers, and compression of the layers in the stack. Variations in any one characteristic may be combined with variations in one or more other characteristics throughout the stack. For example, variations in chemical composition may be combined with variations in pore size and thickness of the fiber layers.

[0083] In one embodiment, the layers of the composite media include a variation in fiber diameter. That is, the composite media includes one or more layers having a first fiber diameter and one or more layers having a second fiber diameter. The composite media may further include one or more layers having a third, fourth, and subsequent fiber diameters. The layers having a given fiber diameter can be grouped together. The composite media may include a first group of layers having a first fiber diameter and a second group of layers having a second fiber diameter. In some embodiments, the composite media includes a gradient of fiber diameters.

[0084] In one embodiment, the layers of the composite media include a variation in pore size from layer to layer. That is, the composite media includes one or more layers with a first pore size and one or more layers with a second pore size. The composite media may further include one or more layers with a third, fourth, and subsequent pore sizes. The layers with a given pore size can be grouped together. The composite media may include a first group of layers with a first pore size and a second group of layers with a second pore size. In some embodiments, the composite media includes a pore size gradient. The composite media may have an inlet side (upstream side) and an outlet side (downstream side). For example, the composite media may be disposed in a filter having an inlet and an outlet. The composite media may include a layer with a relatively large pore size at the inlet side and a layer with a relatively small pore size at the outlet side. In one embodiment, the composite media has one or more layers on the inlet side with a P95 pore size of 1 μm or more, 2 μm or more, 5 μm or more, 10 μm or more, or 25 μm or more. The P95 pore size of the inlet side one or more layers may be 50 μm or less, 40 μm or less, 30 μm or less, 25 μm or less, 20 μm or less, 15 μm or less, 10 μm or less, or 5 μm or less. The P95 pore size of the inlet side one or more layers may be in the range of 1 μm to 50 μm, or 5 μm to 40 μm. In one embodiment, the composite media has one or more layers on the outlet side with a P95 pore size of 0.1 μm or more, 0.3 μm or more, 0.5 μm or more, 0.75 μm or more, or 1.0 μm or more. The P95 pore size of the one or more layers on the outlet side may be 3.0 μm or less, 2.0 μm or less, 1.5 μm or less, 1.2 μm or less, 1.0 μm or less, 0.75 μm or less, or 0.5 μm or less. The P95 pore size of the one or more layers on the outlet side may be in the range of 0.1 μm to 10 μm, 0.5 μm to 5.0 μm, 0.75 μm to 2.0 μm, 0.8 μm to 1.5 μm, or 1.0 μm to 1.5 μm. In one embodiment, the composite media has a pore size gradient ranging from a maximum P95 pore size of 10 μm to 50 μm on the inlet side to a minimum P95 pore size of 0.1 μm to 1 μm on the outlet side. In some embodiments, layers having different pore sizes are arranged to form a sieve layer (e.g., a stack of multiple layers) on an inlet side of the composite media and a filtration layer (e.g., a stack of multiple layers) on an outlet side of the composite media.The filtration layer may further include fibers made of materials for functionalized filtration or chemical filtration. Materials for functionalized filtration or chemical filtration may include polymers with selected functional groups or other materials such as activated carbon or other adsorbents or absorbents included with the polymeric material. Alternatively or additionally, the sieve layer, filtration layer, or both, may be made of materials that render one or more of the layers hydrophobic or hydrophilic, as desired.

[0085] In one embodiment, the layers of the composite media include a variation in fiber layer thickness. That is, the composite media includes one or more layers having a first fiber layer thickness and one or more layers having a second fiber layer thickness. The composite media may further include one or more layers having a third, fourth, and subsequent fiber layer thicknesses. The fiber layers having a given fiber layer thickness can be grouped together. The composite media may include a first group of layers having a first fiber layer thickness and a second group of layers having a second fiber layer thickness. In some embodiments, the composite media includes a gradient of fiber layer thickness. In general, fiber layers having larger pore sizes can be constructed thicker to accommodate a larger amount of captured contaminants, while fiber layers having smaller pore sizes can be constructed thinner to limit the pressure drop across these layers.

[0086] In one embodiment, the layers of the composite media include a change in the chemical composition of the fibers from layer to layer. That is, the composite media includes one or more layers having a first chemical composition and one or more layers having a second chemical composition. The composite media may further include one or more layers having a third, fourth, and subsequent chemical compositions. The layers having a given chemical composition can be grouped together. The composite media may include a first group of layers having a first chemical composition and a second group of layers having a second chemical composition. In some embodiments, the composite media includes a gradient of chemical composition. The composite media may have an inlet side and an outlet side. For example, the composite media may be disposed in a filter having an inlet side and an outlet side. The composite media may include a layer having a given chemical composition at the inlet side and a layer having another chemical composition at the outlet side. In some embodiments, the layer at the outlet side is made or coated with a composition suitable for functionalized or chemical filtration. Materials for functionalized filtration or chemical filtration may include polymers with selected functional groups or other materials such as activated carbon or other adsorbents or absorbents included with the polymeric material. Alternatively or additionally, in some embodiments, some layers may be made of materials that render them hydrophobic or hydrophilic as desired. Composite media may include a hydrophobic or hydrophilic gradient throughout the stack.

[0087] In some embodiments, the stack includes one or more layers suitable to act as a packing layer. The packing layer may be disposed on the inlet (upstream) side of the composite media. The packing layer may include one or more fine fiber layers, each of which may be supported by a substrate. In general, the packing layer exhibits properties suitable for packing the layer with the pollutant of interest. For example, the packing layer may have a larger pore size than the rest of the stack. Such a packing layer may be suitable for sieving. The packing layer may have a chemical composition that has an affinity for the pollutant of interest. The P95 pore size of one or more layers used as a packing layer may be 2 μm or more, 3 μm or more, 4 μm or more, or 5 μm or more. The P95 pore size may be 20 μm or less, 15 μm or less, 12 μm or less, 10 μm or less, or 8 μm or less. The P95 pore size may range from 2 μm to 20 μm, 3 μm to 15 μm, 4 μm to 10 μm, or 5 μm to 8 μm. The pore size can be selected based on the contaminant of interest. The fiber diameter of one or more layers used as a packing layer may be 500 nm or more, 750 nm or more, or 1 μm or more. The fiber diameter may be 3 μm or less, 2 μm or less, 1.5 μm or less, or 1.2 μm or less. In some embodiments, the fibers have diameters in the range of 500 nm to 3 μm or 1.0 μm to 2 μm. Some larger fibers may be present in the layer to act as a scaffold. Such scaffold fibers may be 15 μm or up to 20 μm in size. The portion of the laminate intended to act as a packing layer may include a combination of features, which may be present in each fiber layer in the packing layer or in multiple separate fiber layers in the packing layer. For example, the packed bed may include one or more layers constructed based on the sieving capacity of contaminants and one or more other layers constructed based on the affinity or sieving capacity of different sizes or types of contaminants.

[0088] In one embodiment, the layers of the composite media are compressed to different degrees. That is, the composite media includes a first plurality of fibrous layers with a first degree of compression and a second plurality of fibrous layers with a second degree of compression different from the first degree of compression. The composite media may further include one or more fibrous layers with third, fourth, and subsequent degrees of compression. The layers may be compressed together during the manufacture of the stack or by using a housing (e.g., a filter housing) that compresses the stack to different degrees of compression. Referring now to FIG. 4, a schematic cross-sectional view of a filter 1′ is shown using a housing 4 that applies different degrees of compression to the stack of layers 61, 62, 63. The number of stacks and the number of layers shown in each stack 61, 62, 63 are for illustrative purposes only and do not represent the actual number of layers. Each stack 61, 62, 63 may include 20 or more layers. The first laminate 61 can be at a first degree of compression, the second laminate 62 can be at a second degree of compression, and the third laminate 63 can be at a third degree of compression. The degree of compression may increase continuously from the inlet end 41 to the outlet end 42 of the filter 1'. In some embodiments, a composite media, or a filter including multiple composite media, includes a gradient of compression degrees. The higher the degree of compression, the smaller the effective pore size of the laminate may be. By applying different degrees of compression, different effective pore sizes of the various laminates can be achieved. In some embodiments, a gradient of compression degrees is used to achieve a gradient of effective pore size.

[0089] Below is a list of example embodiments according to the present disclosure.

[0090] According to embodiment 1, the composite medium comprises a laminate having 20 or more layers, each layer comprising: a substrate having a first major surface and an opposing second major surface; a fiber layer including polymer fibers having a diameter of 100 nm to 1.5 μm stacked on a first main surface of the substrate; each fiber layer individually having a thickness of 5 μm to 100 μm, and each layer individually having a P95 pore size of 0.1 μm to 10 μm.

[0091] Embodiment 2 is the composite media of embodiment 1, wherein the substrate comprises a nonwoven substrate.

[0092] Embodiment 3 is the composite medium of embodiment 1 or 2, wherein the substrate comprises a membrane.

[0093] Embodiment 4 is the composite medium of any one of embodiments 1-3, wherein the laminate comprises a layer that includes two or more fibrous layers, and optionally each layer of the laminate includes two or more fibrous layers.

[0094] Example 5 is the composite media of Example 4, wherein the laminate includes a layer with a second fibrous layer stacked on the second major surface of the substrate.

[0095] Embodiment 6 is the composite medium of any one of embodiments 1-5, wherein the P95 pore size of each layer is individually 0.1 μm or more, 0.3 μm or more, 0.5 μm or more, 0.7 μm or more, or 1.0 μm or more. The P95 pore size of each layer may be individually 10 μm or less, 7.5 μm or less, 5.0 μm or less, 3.0 μm or less, 2.0 μm or less, or 1.5 μm or less. The P95 pore size of the layers may be in the range of 0.1 μm to 10 μm, 0.5 μm to 5.0 μm, 0.7 μm to 2.0 μm, 0.8 μm to 1.5 μm, or 1.0 μm to 1.5 μm.

[0096] Embodiment 7 is the composite medium of any one of embodiments 1-6, wherein the pore sizes of the fibrous layers form a pore size gradient across the laminate.

[0097] Embodiment 8 is the composite media of embodiment 7, wherein the composite media has an inlet side and an outlet side, with a pore size gradient from a maximum pore size of 50 μm at the inlet side to a minimum pore size of 0.1 μm at the outlet side.

[0098] A ninth embodiment is the composite medium of any one of the first to eighth embodiments, wherein the P95 pore size of the laminate is 0.01 μm or more, 0.05 μm or more, 0.1 μm or more, 0.3 μm or more, 0.5 μm or more, 0.75 μm or more, or 1.0 μm or more. The P95 pore size of the laminate may be 2.5 μm or less, 2.2 μm or less, 2.0 μm or less, 1.75 μm or less, 1.5 μm or less, or 1.0 μm or less. The P95 pore size of the laminate may be 0.01 μm to 2.5 μm, 0.1 μm to 2.0 μm, or 0.5 μm to 1.5 μm.

[0099] Embodiment 10 is the composite medium of any one of embodiments 1-9, wherein the laminate comprises 50 or more, 100 or more, 200 or more, 300 or more, or 500 or more layers. The laminate may include 3000 or less, 2500 or less, 2000 or less, 1500 or less, or 1000 or less layers. The number of layers in the laminate may be 100-3000, 300-2000, or 500-1000.

[0100] Embodiment 11 is the composite medium of any one of embodiments 1 to 10, wherein the laminate includes a first fiber layer having a first composition and a second fiber layer having a second composition different from the first composition.

[0101] Example 12 is the composite media of Example 11, wherein the fibrous layers of the laminate form a chemical composition gradient across the laminate.

[0102] Embodiment 13 is the composite medium of any one of Embodiments 1 to 10, in which each layer in the laminate has the same composition and structure.

[0103] Embodiment 14 is any one of the composite media of embodiments 1 to 13, wherein the laminate includes a first plurality of layers having a first degree of compression and a second plurality of layers having a second degree of compression different from the first degree of compression.

[0104] Example 15 is the composite media of Example 14, wherein the layers have a gradient of compression across the stack.

[0105] Embodiment 16 is a method for preparing a composite medium having an initial water flux of 100 mL / cm 2 / hour / kPa or more, 120mL / cm 2 / hour / kPa or more, 150mL / cm 2 / hour / kPa or more, 175mL / cm 2 / hour / kPa or more, or 200mL / cm 2 16. The composite medium of any one of embodiments 1 to 15, wherein the initial water flux is 350 mL / cm 2 / hr / kPa or more. 2 / hour / kPa or less, 300mL / cm 2 / hour / kPa or less, or 250mL / cm 2 / hour / kPa or less. The initial water flux may be 100 mL / cm 2 / hour / kPa~350mL / cm 2 / hour / kPa, or 120mL / cm 2 / hour / kPa~300mL / cm 2 / time / kPa.

[0106] In a seventeenth embodiment, the surface area to volume ratio of the fiber layer is less than 1 μm -1 More than 2μm -1 or more than 5μm -1 The composite medium according to any one of the first to sixth embodiments, wherein the SAVR of the fiber layer is 20 μm or less. -1 Less than or equal to 15μm -1 The SAVR of the fiber layer may be less than 1 μm. -1 ~20μm -1 , or 2 μm -1 ~15μm -1 may be also possible.

[0107] Embodiment 18 is the composite medium of any one of embodiments 1-17, wherein the diameter of the polymer fibers is 100 nm or more, 200 nm or more, 300 nm or more, 400 nm or more, or 500 nm or more. The diameter of the polymer fibers may be 1.5 μm or less, 1.2 μm or less, or 1.0 μm or less. The polymer fibers may have a diameter in the range of 100 nm to 1.5 μm, 300 nm to 1.2 μm, or 500 nm to 1.0 μm.

[0108] Embodiment 19 is the composite medium of any one of embodiments 1-18, wherein the thickness of each fiber layer of the laminate may be individually 5 μm or more, 10 μm or more, 25 μm or more, or 50 μm or more. The thickness of each fiber layer may be individually 100 μm or less, 80 μm or less, or 60 μm or less. The thickness of the fiber layer may be 5 μm to 100 μm, 10 μm to 80 μm, or 20 μm to 60 μm. The thickness of each fiber layer is not necessarily the same throughout the laminate. Different fiber layers in the laminate may have different thicknesses. The fiber layers in the laminate may form a fiber layer thickness gradient throughout the laminate.

[0109] Embodiment 20 is the composite medium of any one of embodiments 1 to 19, wherein the thickness of the substrate is 50 μm or more, 100 μm or more, or 500 μm or more. The thickness of the substrate may be 1000 μm or less, 750 μm or less, or 500 μm or less. The thickness of the substrate may be 50 μm to 1000 μm, or 100 μm to 500 μm. The total thickness of the layer (combination of substrate and fiber layer) may be 55 μm to 1100 μm, or 150 μm to 600 μm.

[0110] Embodiment 21 is the composite medium of any one of embodiments 1-20, wherein the composite medium is configured for filtration of a liquid. The liquid may be an aqueous liquid. The liquid may be a non-aqueous liquid.

[0111] A twenty-second embodiment is a filter including a housing and the composite medium of any one of the first to twenty-first embodiments disposed within the housing.

[0112] Embodiment 23 is the filter of embodiment 22, wherein the filter is a syringe filter.

[0113] Embodiment 24 is the filter of embodiment 22 or 23, wherein the filter housing is configured to compress the first plurality of layers to a first degree and compress the second plurality of layers to a second degree, the second degree of compression being different from the first degree of compression.

[0114] Embodiment 25 is the filter of embodiment 24, wherein the layers have a gradient of compression across the stack.

[0115] Embodiment 26 is a composite medium comprising layers of a laminate, each layer comprising a fiber layer, the fiber layer being stacked on a surface of a substrate and comprising polymer fibers having a diameter of 100 nm to 1.5 μm, each fiber layer having an individual thickness of 5 μm to 100 μm, and each layer having an individual P95 pore size of 0.1 μm to 10 μm; At least two of the layers are composite media including a first type of fiber layer adjacent to a second type of fiber layer, where the first type of fiber layer of the first layer is not perfectly aligned with the first type of fiber layer of the second layer.

[0116] Embodiment 27 is the composite media of embodiment 26, wherein the first type of fibrous layer and the second type of fibrous layer differ in solidity, fiber size, pore size, chemical composition, or a combination thereof.

[0117] Embodiment 28 is the composite medium of embodiment 26 or 27, further comprising one or more of the features of embodiments 1-21.

[0118] Embodiment 29 is the composite media of any one of embodiments 26-28 disposed within a filter housing, optionally wherein the filter is a syringe filter.

[0119] Embodiment 30 is the composite media of embodiment 29, wherein the filter housing is configured to compress the first plurality of layers to a first degree and compress the second plurality of layers to a second degree, the second degree of compression being different than the first degree of compression, and optionally the plurality of layers having a gradient of compression across the stack.

[0120] All references and publications cited herein are expressly incorporated by reference in their entirety into this disclosure, except where they directly contradict this disclosure. Although specific embodiments are illustrated and described herein, those skilled in the art will understand that the specific embodiments illustrated and described may be substituted with various alternative and / or equivalent implementations without departing from the scope of the present disclosure. It is not intended that the disclosure be unduly limited by the exemplary embodiments and examples described herein, which examples and embodiments are presented merely as examples, and the scope of the present disclosure is intended to be limited only by the claims.

Claims

1. and a laminate having 20 or more layers, each layer comprising: a substrate having a first major surface and an opposite second major surface; and fiber layers comprising polymer fibers having diameters of 100 nm to 1.5 μm stacked on the first major surface of the substrate, each fiber layer having an individual thickness of 5 μm to 100 μm, and each layer having an individual P95 pore size of 0.1 μm to 10 μm.

2. The composite media of claim 1 , wherein the substrate comprises a nonwoven substrate.

3. The composite media of claim 1 or 2, wherein the substrate comprises a membrane.

4. 3. The composite medium of claim 1 or 2, wherein the laminate comprises a layer comprising two or more fibrous layers, optionally each layer of the laminate comprising two or more fibrous layers, and optionally the laminate comprises a layer comprising a second fibrous layer stacked on the second major surface of the substrate.

5. 3. The composite media of claim 1 or 2, wherein the pore size of the layer is between 0.5 μm and 5.0 μm, between 0.7 μm and 2.0 μm, or between 0.8 μm and 1.5 μm.

6. 3. The composite medium of claim 1 or 2, wherein the pore sizes of the fibrous layers form a pore size gradient throughout the laminate, and optionally the composite medium has an inlet side and an outlet side, the pore size gradient ranging from a maximum pore size of 50 μm at the inlet side to a minimum pore size of 0.1 μm at the outlet side.

7. 3. The composite medium according to claim 1, wherein the laminate has a pore size of 0.01 μm to 2.5 μm.

8. 3. The composite media of claim 1 or 2, wherein the stack has 100 to 3000, 300 to 2000, or 500 to 1000 layers.

9. 3. The composite medium of claim 1 or 2, wherein the laminate comprises a first fibrous layer having a first composition and a second fibrous layer having a second composition different from the first composition, and optionally the fibrous layers of the laminate form a chemical composition gradient throughout the laminate.

10. 3. A composite medium according to claim 1 or 2, wherein each layer in the stack has the same composition and structure.

11. 3. The composite medium of claim 1, wherein the laminate comprises a first plurality of layers having a first degree of compression and a second plurality of layers having a second degree of compression different from the first degree of compression.

12. 12. The composite media of claim 11, wherein the layers have a gradient of compression across the stack.

13. The initial water flux of the composite medium is 150 mL / cm ２ / hour / kPa or more ~300mL / cm ２ 3. The composite medium according to claim 1, wherein the thermal expansion coefficient is 1 / hour / kPa.

14. The fiber layer is 1 μm －１ and optionally the fiber layer has a surface area to volume ratio of 20 μm or more. －１ 3. A composite medium according to claim 1 or 2, having the following surface area to volume ratio:

15. Housing and and a composite media according to claim 1 or 2 disposed within said housing, said filter optionally being a syringe filter.

16. 16. The filter of claim 15, wherein the filter housing is configured to compress a first plurality of layers to a first degree and a second plurality of layers to a second degree, the second degree of compression being different from the first degree of compression, and optionally the plurality of layers having a gradient of compression across the stack.

Images