Filtration media

Abstract

To provide a filtration medium and a method of filtering a liquid stream that eliminate a concern that glass microfibers may be released from the filtration media resulting in environmental contamination or, in the case of filtered fuel, resulting in damage to the internal combustion engine.SOLUTION: There is provided a nonwoven filtration medium including: 25 wt.% to 75 wt.% of a bicomponent fiber having a fiber diameter in a range of at least 1 microns to at maximum 30 microns; 5 wt.% to 50 wt.% of a small filtration efficiency fiber having a fiber diameter of at least 0.1 micron and less than 1 micron; 10 wt.% to 50 wt.% of a large filtration efficiency fiber having a fiber diameter in a range of 1 micron to 5 microns; and 5 wt.% to 25 wt.% of a microfibrillated cellulose fiber. Therein the nonwoven filtration medium is substantially free of resin.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims the benefit of U.S. Provisional Patent Application No. 63 / 004,926, filed April 3, 2020, and U.S. Provisional Patent Application No. 63 / 081,143, filed September 21, 2020, the disclosures of which are incorporated herein by reference in their entireties. [Background technology]

[0002] Filtration media, such as those used for filtering fuels, often contain glass microfibers. However, during certain types of filtration, the glass microfibers can become detached from the filtration media and cause environmental pollution or, in the case of filtered fuel, damage to the internal combustion engine. Summary of the Invention [Means for solving the problem]

[0003] The present disclosure describes filtration media that are preferably substantially glass-free or glass-free. In some embodiments, when the filtration media is substantially glass-free or glass-free, the filtration media preferably exhibits filtration capacity and efficiency that is equal to or greater than similar glass-containing filtration media.

[0004] In one aspect, the present disclosure provides a nonwoven filtration medium comprising: 25% to 85% by weight of bicomponent fibers having a fiber diameter in the range of 5 microns to 25 microns and a fiber length of 0.1 cm to 15 cm; 5% to 50% by weight of small filtration efficiency fibers having a fiber diameter of at least 0.1 micron and less than 1 micron; 10% to 50% by weight of high filtration efficiency fibers having a fiber diameter in the range of 1 micron to 5 microns; and 5% to 25% by weight of microfibrillated fibers, wherein a majority of the microfibrillated fibers have a transverse dimension of up to 4 microns; wherein the nonwoven filtration medium is substantially free of glass fibers.

[0005] In some embodiments, the bicomponent fiber includes a structural polymer portion and a thermoplastic binder polymer portion, the structural polymer portion having a melting point higher than the melting point of the binder polymer portion. In some embodiments, the structural polymer portion of the bicomponent fiber has a melting point of at least 240°C, and the binder polymer portion of the bicomponent fiber has a melting point in the range of 100°C to 190°C.

[0006] In some embodiments, the low filtration efficiency fibers have a fiber diameter of at least 0.4 microns to less than 1 micron.

[0007] In some embodiments, the high filtration efficiency fibers have a fiber diameter in the range of 2 microns to 4 microns.

[0008] In some embodiments, the low filtration efficiency fibers comprise PET or the high filtration efficiency fibers comprise PET; or both the low filtration efficiency fibers and the high filtration efficiency fibers comprise PET.

[0009] In some embodiments, the microfibrillated fibers comprise microfibrillated cellulose fibers.

[0010] In some embodiments, the nonwoven filtration media has a solidity in the range of 5% to 15%. In some embodiments, the nonwoven filtration media has a solidity of 24 g / m 2 ~100g / m 2 In some embodiments, the nonwoven filtration media has a basis weight in the range of 0.5 microns to 20 microns. In some embodiments, the nonwoven filtration media has a P95 / P50 ratio in the range of 1.5 to 3. In some embodiments, the nonwoven filtration media has a thickness in the range of 0.12 mm to 1 mm. In some embodiments, the nonwoven filtration media has a pore size ...1 ft 2 in 0.5 inches of water. 3 / ft 2 / min to 100ft in 0.5 inches of water 3 / ft 2 / min range.

[0011] In some embodiments, the nonwoven filtration media is substantially free of resin.

[0012] In some embodiments, the nonwoven filtration media does not include glass fibers.

[0013] In another aspect, the present disclosure describes a method for filtering a liquid stream, the method including passing the liquid stream containing contaminants through a nonwoven filtration medium to remove the contaminants from the liquid stream. In some embodiments, the liquid stream includes fuel, hydraulic oil, process water, air, diesel engine fluid (DEF), diesel engine lubricating oil, or blow-by gas, or a combination thereof.

[0014] As used herein, a micron is equivalent to a micrometer (μm).

[0015] As used herein, a "fiber" has an average fiber diameter of up to 100 micrometers.

[0016] As used herein, "fibers" have an aspect ratio (i.e., length to transverse dimension) of greater than 3:1, preferably greater than 5:1. For example, fiberglass typically has an aspect ratio of greater than 100:1. In this context, the "transverse dimension" is the width (two-dimensional) or diameter (three-dimensional) of the fiber. The term "diameter" refers to either the diameter of a circular cross-section of the fiber or the largest cross-sectional dimension of a non-circular cross-section of the fiber. Fiber length may be finite or infinite, depending on the desired result.

[0017] As used herein, the "β ratio" or "β" is the ratio of upstream particles to downstream particles under steady flow conditions (ISO 16889:2008), as explained in the Examples section. The more efficient the filter, the higher the β ratio. The β ratio is defined as:

number

[0018] As used herein, unless otherwise specified, pore sizes (e.g., P5, P50, and P95) and pore size ratios (e.g., P95 / P50) are determined using capillary flow porometry. Capillary flow porometry can be performed using a continuous pressure scan mode. It can be useful to use silicone oil, which has a surface tension of 20.1 dynes / cm and a wetting contact angle of 0, as the wetting liquid. The sample is first tested in a dry state, varying from low to high pressure, and then in a wet state, also varying from low to high pressure. Testing is typically performed at ambient temperature conditions (e.g., 20°C to 25°C). 256 data points can be collected across the entire pressure scan range for both the wetting and drying 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).

[0019] As used herein, the value P(x%) is the calculated pore size where the wetting curve is equal to (100-x)% of the drying curve, as determined using the methods described herein. Although a calculated value, it can be understood to represent the point where x% of the total flow through the bed passes through pores of that pore size or smaller. For example, P50 (mid-flow pore size) represents the point where the wetting curve is equal to half the drying curve and can be considered the pore size where 50% of the total flow through the bed passes through pores of that pore size or smaller.

[0020] As used herein, "pressure drop" (also referred to herein as "dP" or "ΔP") relates to the pressure (applied by a pump) required to force a fluid through a filter or filter media (before contaminants are added) at a specific fluid velocity. Unless otherwise specified, the pressure drop is the clean pressure drop measured as described in ISO 16889:2008. Samples should be tested using a test flow rate of 16 L / min. The test should be run until the differential pressure between the end elements is 320 kPa.

[0021] The term "substantially free," as used herein, indicates that the filtration medium does not contain the referenced component (e.g., glass fiber or resin) in an amount that would materially affect the activity or behavior of the filtration medium. The term is intended to mean containing an insignificant amount of the component that does not substantially contribute to the filtration performance of the filtration medium. For example, a substantially glass-free filtration medium may contain less than 1% glass fiber by weight. For example, a substantially resin-free filtration medium may contain less than 5% resin by weight. For example, a substantially glass-free filtration medium may contain less than 1% glass fiber by weight. For example, a substantially resin-free filtration medium may contain less than 5% resin by weight.

[0022] The term "free," as used herein, indicates that the filtration media does not contain any of the featured component (e.g., glass fiber or resin). For example, a "glass-free" filtration media would contain no glass, and a "resin-free" media would contain no resin.

[0023] Reference to a standard test method (eg, ASTM, TAPPI, etc.) is intended to refer to the most recent version of that method available at the time of filing this disclosure, unless otherwise specified.

[0024] The terms "preferred" or "preferably" refer to embodiments of the present invention that may offer certain benefits in certain circumstances. However, other embodiments may also be preferred, in the same or other circumstances. Furthermore, the mention 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 this specification.

[0025] The terms "comprises" and their derivatives do not have a limiting meaning where these terms appear in the description and claims. Such terms are understood to mean the inclusion of a stated step or element or group of steps or elements, but not the exclusion of other steps or elements or groups of steps or elements.

[0026] "Consisting of" means including and limited to everything that follows the phrase "consisting of." Thus, the phrase "consisting of" indicates that the listed elements are required or essential, and that no other elements may be present. "Consisting essentially of" means including the elements listed after this phrase, and is limited to other elements that do not interfere with or contribute to the activity or action specified in this disclosure for the listed elements. Thus, the phrase "consisting essentially of" indicates that the listed elements are required or essential, but that other elements are optional and may or may not be present depending on whether they materially affect the activity or action of the listed elements.

[0027] Unless otherwise specified, "a," "an," "the," and "at least one" are used interchangeably to mean one or more.

[0028] As used herein, the term "or" is generally used in its ordinary sense, including "and / or," unless the content clearly dictates otherwise.

[0029] The term "and / or" means one or all of the listed elements or a combination of any two or more of the listed elements.

[0030] As used herein, the recitations of numerical ranges by endpoints include all numbers subsumed within that range (e.g., 1 to 5 includes 1, 1.5, 2, 2.75, 3, 3.80, 4, 5, etc.).

[0031] As used herein, "up to a number" (eg, up to 50) includes the number (eg, 50).

[0032] The terms "in the range" or "within a range" (and similar descriptions) include the end points of the stated range.

[0033] In any method disclosed herein that includes separate steps, those steps may be performed in any convenient order possible, and where appropriate, two or more steps may be combined and performed simultaneously.

[0034] All headings are for the convenience of the reader and should not be construed as limiting the meaning of the text that follows the heading, unless specifically stated.

[0035] Throughout this specification, references to "one embodiment," "embodiment," "particular embodiment," or "some embodiments" mean that a particular feature, configuration, composition, or characteristic described in connection with an embodiment is included in at least one embodiment of the present disclosure. Thus, the appearances of such phrases in various places throughout this specification do not necessarily refer to the same embodiment of the present disclosure. Furthermore, particular features, configurations, compositions, or characteristics may be combined in any suitable manner in one or more embodiments.

[0036] Unless otherwise indicated, all numbers expressing quantities, molecular weights, and the like of ingredients used in the specification and claims should be understood in all instances to be modified by the term "about." The term "about," as used herein in connection with a measured quantity, refers to the variation in that measured quantity that is expected by one of ordinary skill in the art making the measurement and exercising a level of care commensurate with the purpose of the measurement and the precision of the measuring device used. Accordingly, unless specifically indicated to the contrary, the numerical parameters set forth in the specification and claims are approximations that may vary depending upon the desired properties sought to be obtained by the present invention. At the very least, and not as an attempt to limit the doctrine of equivalents to the scope of the claims, each numerical parameter should be construed in light of the number of reported significant digits and by applying ordinary rounding techniques.

[0037] Notwithstanding that the numerical ranges and parameters setting forth the broad scope of the invention are approximations, the numerical values ​​set forth in the specific examples are reported as precisely as possible, however, all numerical values ​​inherently contain a range necessarily resulting from the standard deviation found in their respective testing measurements.

[0038] The above summary of the present invention is not intended to describe each disclosed embodiment or every implementation of the present invention. The following description more particularly exemplifies exemplary embodiments. In several places throughout the specification, guidance is provided by lists of examples that can be used in various combinations. In each instance, the recited list serves only as a representative group and should not be interpreted as an exclusive list. [Brief explanation of the drawings]

[0039] [Figure 1]1 is a pictorial representation of a simulation of a glass-free filtration media containing 14 μm diameter bicomponent (Bico) fibers, 0.7 μm diameter polyethylene terephthalate (PET) fibers, 2.5 μm diameter PET fibers, and 1 μm diameter microfibrillated rayon fibers (described in more detail in Example 1). The simulation of the rayon fibers does not maximize their cohesion. [Figure 2] Figure 1 shows the test β values ​​measured to determine β = 10,000 for handsheets prepared as described in Example 2 and containing 24 g / m2 of 14 μm diameter bicomponent fiber and varying amounts of 700 nm diameter PET fiber (circles), or 14 μm diameter bicomponent fiber and varying amounts of 700 nm diameter PET fiber, 1 μm diameter microfibrillated rayon fiber (Lyocell), and 2.5 μm diameter PET fiber (squares). Trendlines for each data set were calculated using the built-in curves in Excel. [Figure 3] FIG. 1 shows β4 μm measured for media prepared as described in Example 3. [Figure 4] FIG. 1 shows β4 μm plotted against the weight percent of microfibrillated rayon and 700 nm PET fibers in the medium at varying amounts of each fiber type (as described in more detail in Example 4). [Figure 5A] FIG. 1 shows P95 / P50 plotted against fiber weight percent of microfibrillated rayon in a medium for varying amounts of microfibrillated rayon (as described in more detail in Example 4). [Figure 5B] FIG. 1 shows P95 / P50 plotted against fiber mass percent of 2.7 μm diameter PET fiber in a medium for varying amounts of 2.7 μm diameter PET fiber (as described in more detail in Example 4). [Figure 6A]FIG. 1 shows the Figure of Merit (FOM) plotted against the fiber weight percent of microfibrillated rayon in the medium for varying amounts of microfibrillated rayon (as described in more detail in Example 4). [Figure 6B] FIG. 1 shows the FOM plotted against the fiber mass percent of 0.7 μm diameter PET fiber in the medium for varying amounts of 0.7 μm diameter PET fiber (as described in more detail in Example 4). DETAILED DESCRIPTION OF THE INVENTION

[0040] The present disclosure describes filtration media that are preferably substantially glass-free or glass-free. In some embodiments, when the filtration media is substantially glass-free or glass-free, the filtration media preferably exhibits filtration capacity and efficiency that is equal to or greater than similar glass-containing filtration media.

[0041] filtration media In one aspect, the present disclosure describes a filtration medium. The filtration medium is a nonwoven filtration medium. The nonwoven filtration medium is substantially free of glass (including, for example, glass fibers). In some embodiments, the nonwoven filtration medium is glass-free.

[0042] In some embodiments, the nonwoven filtration media includes: bicomponent fibers; "low filtration efficiency fibers" ("low filtration efficiency fibers" as used herein are fibers having a fiber diameter of at least 0.1 microns and less than 1 micron); "high filtration efficiency fibers" ("high filtration efficiency fibers" as used herein are fibers having a fiber diameter in the range of 1 micron to 5 microns); and microfibrillated fibers.

[0043] In some embodiments, the low filtration efficiency fibers or the high filtration efficiency fibers, or both, preferably comprise polyethylene terephthalate (PET).

[0044] In one exemplary embodiment, the nonwoven filtration medium comprises: 25% to 85% by weight bicomponent fibers having a fiber diameter in the range of 5 microns to 25 microns and a fiber length in the range of 0.1 cm to 15 cm; 5% to 50% by weight low filtration efficiency fibers; 10% to 50% by weight high filtration efficiency fibers; and 5% to 25% by weight microfibrillated fibers, wherein a majority of the microfibrillated fibers have a transverse dimension of up to 4 microns.

[0045] One exemplary embodiment is shown in Example 2. As further described in Example 2, the inclusion of fibers having a fiber diameter of at least 0.1 micron and less than 1 micron (700 nm) and fibers having a fiber diameter in the range of 1 micron to 5 microns (2.5 μm) allowed for comparable efficiencies (β) to be achieved while providing a more open structure that would prevent undesirable pressure drop. As shown in Example 3, these efficiencies can be obtained without using fibers having a fiber diameter of at least 0.1 micron and less than 1 micron (see FIG. 3), although such media would be expected to be denser, resulting in undesirably higher pressure drop (dP).

[0046] As is well known to those skilled in the art, the use of smaller fiber sizes will produce filter media with higher filtration efficiency. However, nonwoven filtration media containing only bicomponent fibers and fibers with a fiber diameter of at least 0.1 micron and less than 1 micron will have very low strength, particularly in the fiber matrix of the 0.1-1 micron fibers that form the spaces between the larger bicomponent fibers, making them undesirable for many applications, especially those where the filter media is subject to dynamic forces. While strength can be increased by including a resin, the use of a resin is undesirable because it fills pores in the media that would otherwise be available to capture contaminants, increasing the pressure drop.

[0047] As shown in the results of Example 4, increasing the amount of microfibrillated fibers and fibers with a fiber diameter of at least 0.1 micron and less than 1 micron (700 nm) improves filtration efficiency (see Figure 4). Increasing the amount of microfibrillated fibers increases filter media performance, as reflected in the figure of merit (FOM), which is a measure of a filter media's performance and ability to impart a certain level of clarification to a stream using minimal energy (Figure 6A). In addition, increasing the amount of microfibrillated fibers increases fiber entanglement, thereby increasing the strength of the fiber matrix. Increased strength can also be achieved by using materials capable of forming hydrogen bonds, such as rayon and cellulose.

[0048] However, increasing the amount of microfibrillated fiber also resulted in an increase in the P95 / P50 ratio (Figure 5A), suggesting that the pore size uniformity of the media decreased with increasing amounts of microfibrillated fiber. In contrast, increasing the amount of high filtration efficiency fiber (i.e., fibers with fiber diameters in the 1-5 micron range) resulted in a decrease in the P95 / P50 ratio (Figure 5B), suggesting that the pore size uniformity of the media increased with increasing amounts of high filtration efficiency fiber.

[0049] Therefore, to obtain a glass-free media with the desired filtration efficiency, strength, and uniformity, it is necessary to balance the proportions of bicomponent fibers, low filtration efficiency fibers, high filtration efficiency fibers, and microfibrillated fibers. For example, to improve uniformity, one would want to increase the proportion of high filtration efficiency fibers. To improve filtration efficiency, one would want to increase the proportion of low filtration efficiency fibers.

[0050] In some embodiments, one or more fibers can be selected or treated to modify the electrostatic charge of the medium. The charge typically includes a layer of positive or negative charge trapped at or near the surface of the polymer or a charge cloud accumulated in the bulk of the polymer. The charge can also include polarization charges frozen in the alignment of molecular dipoles. Methods for exposing materials to electric charges are well known to those skilled in the art. These methods include, for example, thermal methods, liquid contact methods, electron beam methods, plasma methods, and corona discharge methods.

[0051] Bicomponent Fiber The filtration media includes bicomponent fibers. Any suitable bicomponent fiber can be used, and the bicomponent fiber can be selected depending on the intended use of the media.

[0052] In some embodiments, the filtration medium includes at least 25%, at least 30%, at least 35%, at least 40%, at least 45%, at least 50%, at least 55%, at least 60%, at least 65%, or at least 70% by weight of bicomponent fibers. In some embodiments, the filtration medium includes up to 30%, up to 35%, up to 40%, up to 45%, up to 50%, up to 55%, up to 60%, up to 65%, up to 70%, up to 75%, or up to 85% by weight of bicomponent fibers. In one exemplary embodiment, the filtration medium includes between 25% and 85% by weight of bicomponent fibers. In another exemplary embodiment, the filtration medium includes between 25% and 75% by weight of bicomponent fibers. In yet another exemplary embodiment, the filtration medium includes 25% to 70% by weight bicomponent fibers. In a further exemplary embodiment, the filtration medium includes 50% by weight bicomponent fibers.

[0053] In some embodiments, the bicomponent fibers have a fiber diameter of at least 1 micron, at least 5 microns, at least 10 microns, at least 15 microns, or at least 20 microns. In some embodiments, the bicomponent fibers have a fiber diameter of up to 5 microns, up to 10 microns, up to 15 microns, up to 20 microns, up to 25 microns, or up to 30 microns. In one exemplary embodiment, the bicomponent fibers have a fiber diameter in the range of 5 microns to 25 microns. In another exemplary embodiment, the bicomponent fibers have a fiber diameter of 14 microns.

[0054] In some embodiments, the bicomponent fibers have a fiber length of at least 0.1 cm, at least 0.5 cm, or at least 1 cm. In some embodiments, the bicomponent fibers have a fiber length of up to 0.5 cm, up to 1 cm, up to 5 cm, up to 10 cm, or up to 15 cm. In one exemplary embodiment, the bicomponent fibers have a fiber length in the range of 0.1 cm to 15 cm. In yet another exemplary embodiment, the bicomponent fibers have a fiber length of 6 mm.

[0055] In some embodiments, the bicomponent fibers include a structural polymer portion and a thermoplastic binder polymer portion, the structural polymer portion having a melting point higher than the melting point of the binder polymer portion.

[0056] The structural polymer portion and the binder polymer portion can be made of any suitable material. For example, the structural polymer portion can include PET, and the binder polymer portion can include copolymer PET (coPET). In an additional example, the structural polymer portion can include PET, and the binder polymer portion can include polyethylene (PE), PET, nylon, polypropylene (PP), polytetrafluoroethylene (PTFE), polyethersulfone (PES), polyphenylene sulfide (PPS), meta-aramid, or para-aramid. In a further example, the binder polymer portion can include polyethylene (PE), polylactic acid (PLA), nylon, ethylene vinyl alcohol (EVOH), polyvinyl chloride (PVC), polyvinylidene fluoride (PVDF) (e.g., KYNAR), or any other polymer or modified polymer designed to have a lower melting point than the core structural polymer.

[0057] In some embodiments, the structural polymer portion is the core and the thermoplastic binder polymer portion is the sheath of a bicomponent fiber.

[0058] In some embodiments, the structural polymer portion of the bicomponent fiber has a melting point of at least 240° C. and the binder polymer portion of the bicomponent fiber has a melting point of up to 115° C. An exemplary bicomponent fiber in which the structural polymer portion has a melting point of at least 240° C. and the binder polymer portion has a melting point of up to 115° C. is 271P, a 14 μm diameter fiber available from Advansa (Hamm, Germany).

[0059] In some embodiments, the structural polymer portion of the bicomponent fiber has a melting point of at least 240° C. and the binder polymer portion of the bicomponent fiber has a melting point in the range of 100° C. to 190° C. In one exemplary embodiment, the structural polymer portion of the bicomponent fiber has a melting point of at least 240° C. and the binder polymer portion of the bicomponent fiber has a melting point in the range of 120° C. to 170° C. In yet another exemplary embodiment, the structural polymer portion of the bicomponent fiber has a melting point of at least 240° C. and the binder polymer portion of the bicomponent fiber has a melting point in the range of 140° C. to 160° C.

[0060] Exemplary bicomponent fibers whose structural polymer portion has a melting point of at least 240°C and whose binder polymer portion has a melting point within the range of 100°C to 190°C include: TJ04CN (having a binder polymer portion with a melting point of 110°C), TJ04BN (having a binder polymer portion with a melting point of 150°C) (both available from Teijin Fibers Limited, Osaka, Japan); 271P (having a binder polymer portion with a melting point of 110°C) (available from Advansa, Hamm, Germany); and T-202 or T-217 (each having a binder polymer portion with a melting point of 180°C) (both available from Fiber Innovation Technology, Inc., Johnson City, Tenn.).

[0061] In some embodiments, the bicomponent fiber may include a first bicomponent fiber and a second bicomponent fiber. In one exemplary embodiment, the bicomponent fiber may include a first bicomponent fiber whose structural portion has a melting point of at least 240° C. and whose binder polymer portion has a melting point of up to 115° C., and a second bicomponent fiber whose structural polymer portion has a melting point of at least 240° C. and whose binder polymer portion has a melting point in the range of 100° C. to 190° C. For example, such bicomponent fibers include both Advansa 271P and TJ04BN.

[0062] Low filtration efficiency fiber The filtration media includes "low filtration efficiency fibers," which, as used herein, are fibers having a fiber diameter of at least 0.1 microns and less than 1 micron.

[0063] In some embodiments, the low filtration efficiency fibers are preferably PET fibers. In some embodiments, the low filtration efficiency fibers may consist essentially of PET. In some embodiments, the low filtration efficiency fibers may consist of PET.

[0064] Additionally or alternatively, the low filtration efficiency fibers may include nylon, acrylic, rayon, polypropylene, polyethylene, ethylene vinyl alcohol (EVOH), polylactic acid (PLA), polyvinyl alcohol (PVA), polyvinyl chloride (PVC), polytetrafluoroethylene (PTFE), or other suitable melt-soluble polymers.

[0065] In some embodiments, the filtration medium includes at least 5%, at least 10%, at least 15%, at least 20%, at least 25%, at least 30%, at least 35%, at least 40%, or at least 45% by weight of small filtration efficiency fibers. In some embodiments, the filtration medium includes up to 15%, up to 20%, up to 25%, up to 30%, up to 35%, up to 40%, up to 45%, up to 50%, or up to 55% by weight of small filtration efficiency fibers. In one exemplary embodiment, the filtration medium includes between 5% and 50% by weight of small filtration efficiency fibers. In yet another exemplary embodiment, the filtration medium includes between 10% and 50% by weight of small filtration efficiency fibers. In yet another exemplary embodiment, the filtration medium includes between 10% and 40% by weight of small filtration efficiency fibers. In a further exemplary embodiment, the filtration media includes 10% to 25% by weight of low filtration efficiency fibers.

[0066] In some embodiments, the low filtration efficiency fibers have a fiber diameter of at least 0.1 microns, at least 0.2 microns, at least 0.3 microns, at least 0.4 microns, at least 0.5 microns, at least 0.6 microns, or at least 0.7 microns. In some embodiments, the low filtration efficiency fibers have a fiber diameter of up to 0.7 microns, up to 0.8 microns, up to 0.9 microns, or less than 1 micron. For example, in one exemplary embodiment, the low filtration efficiency fibers have a fiber diameter of at least 0.4 microns and less than 1 micron. In yet another exemplary embodiment, the low filtration efficiency fibers have a fiber diameter in the range of 0.6 microns to 0.8 microns. In a further exemplary embodiment, the low filtration efficiency fibers have a fiber diameter of 0.7 microns.

[0067] In some examples, the low filtration efficiency fibers are PET fibers having a fiber diameter of 0.7 microns.

[0068] In some embodiments, the low filtration efficiency fibers have a length of at least 0.5 mm, at least 1 mm, or at least 1.5 mm. In some embodiments, the low filtration efficiency fibers have a length of up to 10 mm, up to 11 mm, up to 12 mm, or up to 15 mm. In one exemplary embodiment, the low filtration efficiency fibers have a length in the range of 1 mm to 15 mm. In a further exemplary embodiment, the low filtration efficiency fibers have a length in the range of 1 mm to 12 mm.

[0069] In some embodiments, when the low filtration efficiency fibers comprise PET, the PET of the low filtration efficiency fibers preferably has a melting point of at least 250°C, more preferably at least 275°C, and even more preferably at least 290°C.

[0070] High filtration efficiency fiber The filtration media further comprises "high filtration efficiency fibers," where "high filtration efficiency fibers," as used herein, are fibers having a fiber diameter in the range of 1 micron to 5 microns.

[0071] In some embodiments, the high filtration efficiency fibers are preferably PET fibers. In some embodiments, the high filtration efficiency fibers may consist essentially of PET. In some embodiments, the high filtration efficiency fibers may consist of PET.

[0072] Additionally or alternatively, the high filtration efficiency fibers may include nylon, acrylic, rayon, polypropylene, polyethylene, ethylene vinyl alcohol (EVOH), polylactic acid (PLA), polyvinyl alcohol (PVA), polyvinyl chloride (PVC), polytetrafluoroethylene (PTFE), or other suitable melt-soluble polymers.

[0073] In some embodiments, the filtration medium comprises at least 10%, at least 15%, at least 20%, at least 25%, or at least 30% by weight of high filtration efficiency fibers. In some embodiments, the filtration medium comprises up to 15%, up to 20%, up to 25%, up to 30%, up to 35%, up to 40%, up to 45%, or up to 50% by weight of high filtration efficiency fibers. In one exemplary embodiment, the filtration medium comprises between 10% and 50% by weight of high filtration efficiency fibers. In yet another exemplary embodiment, the filtration medium comprises between 10% and 40% by weight of high filtration efficiency fibers. In yet another exemplary embodiment, the filtration medium comprises between 10% and 25% by weight of high filtration efficiency fibers.

[0074] In some embodiments, the high filtration efficiency fibers have a fiber diameter of at least 1 micron, at least 1.5 microns, at least 2 microns, at least 3 microns, or at least 4 microns. In some embodiments, the high filtration efficiency fibers have a fiber diameter of up to 1.5 microns, up to 2 microns, up to 3 microns, up to 4 microns, or up to 5 microns. For example, in one exemplary embodiment, the high filtration efficiency fibers have a fiber diameter in the range of 2 microns to 4 microns. In yet another exemplary embodiment, the high filtration efficiency fibers have a fiber diameter in the range of 2 microns to 3 microns. In yet another exemplary embodiment, the high filtration efficiency fibers have a fiber diameter of 2.5 microns. In a further exemplary embodiment, the high filtration efficiency fibers have a fiber diameter of 2.7 microns.

[0075] In some examples, the low filtration efficiency fibers are PET fibers having a fiber diameter of 2.7 microns.

[0076] In some embodiments, the high filtration efficiency fibers have a length of at least 0.5 mm, at least 1 mm, or at least 1.5 mm. In some embodiments, the high filtration efficiency fibers have a length of up to 10 mm, up to 11 mm, up to 12 mm, or up to 15 mm. In one exemplary embodiment, the high filtration efficiency fibers have a length in the range of 1 mm to 15 mm. In a further exemplary embodiment, the high filtration efficiency fibers have a length in the range of 1 mm to 12 mm.

[0077] In some embodiments, when the high filtration efficiency fibers comprise PET, the PET of the high filtration efficiency fibers preferably has a melting point of at least 250°C, more preferably at least 275°C, and even more preferably at least 290°C.

[0078] Microfibrillated Fiber The nonwoven filtration media includes microfibrillated fibers, which, as used herein, are fibers that have been processed to produce fibers with a higher surface area and a more branched structure than unprocessed fibers.

[0079] In some embodiments, the microfibrillated fibers may be microfibrillated acrylic fibers, including, for example, fibrillated CFF fibers (available from Engineered Fiber Technology, Shelton, CT). In some embodiments, the microfibrillated fibers may be microfibrillated cellulose fibers, including, for example, rayons such as Lyocell or TENCEL. In some embodiments, the microfibrillated fibers may be microfibrillated para-aramid fibers, including, for example, TWARON Pulp (Teijin Aramid, BV, The Netherlands). In some embodiments, the microfibrillated fibers may be microfibrillated liquid crystal polymers (LCPs), including, for example, microfibrillated VECTRAN fibers (available from Engineered Fiber Technology, Shelton, CT). In some embodiments, the microfibrillated fibers may be microfibrillated poly-p-phenylene benzobisoxazole (PBO) fibers, including, for example, fibrillated ZYLON fibers (available from Engineered Fiber Technology, Shelton, CT).

[0080] In some embodiments, the filtration medium comprises at least 5%, at least 10%, at least 15%, at least 20%, at least 25%, or at least 30% by weight of microfibrillated fibers. In some embodiments, the filtration medium comprises up to 15%, up to 20%, up to 25%, up to 30%, up to 35%, or up to 40% by weight of microfibrillated fibers. In one exemplary embodiment, the filtration medium comprises between 5% and 40% by weight of microfibrillated fibers. In yet another exemplary embodiment, the filtration medium comprises between 5% and 25% by weight of microfibrillated fibers. In a further exemplary embodiment, the filtration medium comprises between 10% and 40% by weight of microfibrillated fibers. In yet another exemplary embodiment, the filtration medium comprises between 10% and 25% by weight of microfibrillated fibers. In additional exemplary embodiments, the filtration media includes 12.5% ​​or 25% by weight microfibrillated fibers.

[0081] In some embodiments, the microfibrillated fibers include microfibrillated cellulose. Microfibrillated cellulose (MFC) in this specification refers to the material defined by G. Chinga-Carrasco in Nanoscale Research Letters, 2011, 6:417: "MFC materials can consist of (1) nanofibrils, (2) fine fibers, (3) fiber fragments, and (4) fibers. This means that MFC is not necessarily synonymous with microfibrils, nanofibrils, or any other cellulose nanostructure. However, properly formed MFC materials contain nanostructures, i.e., nanofibrils, as the primary component." The diameters (or "lateral dimensions" in the case of microfibrillated cellulose fibers) of these components are reproduced in Table 1 of the same reference and are as follows: (1) nanofibrils (<0.1 μm); (2) fine fibers (<1 μm); and (3) fibers or fiber fragments (10 μm to 50 μm).

[0082] Furthermore, the term "microfibrillated cellulose" as used herein does not include dry-ground cellulose (also called micronized or ultrafine cellulose) or microcrystalline cellulose obtained by removing the amorphous portion by acid hydrolysis as described in U.S. Pat. No. 5,554,287.

[0083] In some embodiments, a majority (i.e., more than half) of the microfibrillated fibers have a transverse dimension (e.g., width in two dimensions) of at most 1 micron, at most 1.5 microns, at most 2 microns, at most 3 microns, or at most 4 microns. In some embodiments, a majority of the microfibrillated fibers have a transverse dimension of at least 0.5 microns, or at least 0.7 microns. In one exemplary embodiment, a majority of the microfibrillated fibers have a transverse dimension in the range of 0.5 microns to 4 microns. In yet another exemplary embodiment, a majority of the microfibrillated fibers have a transverse dimension in the range of 0.5 microns to 1.5 microns. In a further exemplary embodiment, a majority of the microfibrillated fibers have a transverse dimension of at most 2 microns.

[0084] In some embodiments, the microfibrillated fibers are incorporated within (i.e., dispersed throughout) the fibrous media, thereby forming a filter media (also referred to herein as "filtration media" or "filter media").

[0085] Characteristics of nonwoven filtration media In some embodiments, the nonwoven filtration medium has a solidity of at least 2%, at least 3%, at least 4%, at least 5%, at least 6%, at least 7%, at least 8%, at least 9%, or at least 10%. In some embodiments, the nonwoven filtration medium has a solidity of up to 5%, up to 6%, up to 7%, up to 8%, up to 9%, up to 10%, up to 11%, up to 12%, up to 13%, up to 14%, up to 15%, up to 16%, up to 17%, up to 18%, up to 19%, or up to 20%. In one exemplary embodiment, the nonwoven filtration medium has a solidity in the range of 5% to 15%. In some embodiments, solidity is preferably measured as described in the Examples.

[0086] In some embodiments, the nonwoven filtration media has a tensile strength of at least 20 grams per square meter (g / m 2 ), at least 24g / m 2 , at least 25g / m 2 , at least 30g / m 2 , at least 35g / m 2 , at least 40 g / m 2 , at least 50g / m 2 , at least 60g / m 2 , or at least 70 g / m 2 In some embodiments, the nonwoven filtration media has a basis weight of at most 25 g / m 2 up to a maximum of 30 g / m 2 up to a maximum of 35 g / m 2 up to a maximum of 40 g / m 2 up to a maximum of 50 g / m 2 up to a maximum of 60 g / m 2 up to a maximum of 70 g / m 2 up to a maximum of 75 g / m 2 up to a maximum of 80 g / m 2 up to a maximum of 85 g / m 2 up to a maximum of 90 g / m 2 up to a maximum of 95 g / m 2up to a maximum of 100 g / m 2 or up to 105 g / m 2 In one exemplary embodiment, the nonwoven filtration media has a basis weight of up to 24 g / m 2 ~100g / m 2 In some embodiments, the basis weight is preferably measured using ASTM D646-13.

[0087] In some embodiments, the nonwoven filtration medium has a pore size of at least 0.5 microns, at least 1 micron, at least 1.5 microns, at least 2 microns, at least 3 microns, at least 5 microns, or at least 10 microns. In some embodiments, the nonwoven filtration medium has a pore size of up to 5 microns, up to 10 microns, up to 15 microns, or up to 20 microns. In one exemplary embodiment, the nonwoven filtration medium has a pore size of 0.5 microns to 20 microns. In one exemplary embodiment, the nonwoven filtration medium has a pore size of 2 microns to 15 microns. Pore size, as used herein, refers to the flow pore size calculated as described in ASTM F316-03.

[0088] In some embodiments, the nonwoven filtration medium has a P95 / P50 ratio of at least 1.5 or at least 2. In some embodiments, the nonwoven filtration medium has a P95 / P50 ratio of up to 3.

[0089] In some embodiments, the nonwoven filtration medium has a thickness of at least 0.1 mm, at least 0.12 mm, at least 0.15 mm, or at least 0.2 mm. In some embodiments, the nonwoven filtration medium has a thickness of up to 0.2 mm, up to 0.4 mm, up to 0.5 mm, up to 0.7 mm, or up to 1 mm. In some embodiments, the thickness of the filtration medium is preferably measured according to TAPPI T411 om-15 test method using a foot pressure of 1.5 psi.

[0090] In some embodiments, the nonwoven filtration media has a resistance to at least 1 ft of 0.5 inches of water. 3 / ft 2 / min, at least 5ft in 0.5 inches of water 3 / ft 2 / min or at least 10 ft in 0.5 in. of water 3 / ft 2 / min. In some embodiments, the nonwoven filtration media has a permeability of up to 10 ft / min. in 0.5 inches of water. 3 / ft 2 / min, up to 20ft in 0.5 inches of water 3 / ft 2 / min, up to 50ft in 0.5 inches of water 3 / ft 2 / min, up to 75ft in 0.5 inches of water 3 / ft 2 / min or up to 100ft in 0.5 inches of water 3 / ft 2 / min. In one exemplary embodiment, the nonwoven filtration media has a permeability of up to 1 ft / min in 0.5 inches of water. 3 / ft 2 / min to 100ft in 0.5 inches of water 3 / ft 2 In yet another exemplary embodiment, the nonwoven filtration media has a permeability in the range of up to 10 ft / min with 0.5 inches of water. 3 / ft 2 / min to 75ft in 0.5 inches of water 3 / ft2 / min. In some embodiments, air permeability is preferably measured according to ASTM D737-18.

[0091] In some embodiments, the nonwoven filtration media is substantially free of resin. In some embodiments, the nonwoven filtration media is resin-free. At the time of this invention, resins were often used to maintain fiber spacing in the filter media and to prevent media instability. However, resins clog the pores in the filter media, reducing the solidity and therefore the lifespan of the filtration media.

[0092] Without being bound by theory, it is believed that the use of microfibrillated fibers in combination with high filtration efficiency fibers (fiber diameters in the range of 1 micron to 5 microns) is particularly beneficial in enabling a substantially resin-free filtration medium. It is believed that the microfibrillated fibers provide higher tensile strength, which helps maintain fiber spacing. Furthermore, it is believed that the high filtration efficiency fibers provide a more uniform pore structure.

[0093] In some embodiments, the nonwoven filtration media comprises between 25% and 85% by weight of bicomponent fibers. Using less than 25% by weight of bicomponent fibers is expected to result in a media with insufficient strength, since the binder portion of the bicomponent fibers helps hold the media together during use. Using more than 85% by weight of bicomponent fibers will result in insufficient other fibers in the media to provide the desired filtration efficiency and uniform structure.

[0094] In some embodiments, the nonwoven filtration media comprises low filtration efficiency fibers (fiber diameters of at least 0.1 microns and less than 1 micron) in an amount ranging from 5% to 50% by weight. Using less than 5% by weight of low filtration efficiency fibers often results in a lower filtration efficiency than desired (e.g., a β value greater than 10). 4μmUsing more than 50% by weight of low filtration efficiency fibers will increase the pressure drop and often result in a weaker media because the fibers will not be in contact with other fibers to help hold them in the media.

[0095] In some embodiments, the nonwoven filtration media contains high filtration efficiency fibers (fiber diameters in the range of 1 micron to 5 microns) in an amount in the range of 10% to 50% by weight. Using less than 10% by weight of high filtration efficiency fibers often results in a media with irregular pore sizes. Using more than 50% by weight of high filtration efficiency fibers often results in a media that does not contain enough low filtration efficiency fibers to achieve the desired filtration efficiency or enough bicomponent fibers to provide the necessary strength in use.

[0096] In some embodiments, the nonwoven filtration media comprises microfibrillated fibers in an amount ranging from 5% to 25% by weight. Using less than 5% by weight of microfibrillated fibers often results in a media that lacks sufficient strength and filtration efficiency in use. Using more than 25% by weight of microfibrillated fibers often results in irregular pore sizes (as indicated by a high P95 / P50 ratio).

[0097] In the past, low-melt PET fibers have sometimes been used as a resin replacement, but these fibers melt during the manufacture of nonwoven filtration media and, like resin, clog the pores in the filter media, reducing solidity and therefore lifespan.

[0098] How to use filtration media The filtration media described herein can be used in any manner conceivable to one of ordinary skill in the art, and in some embodiments, the filtration media described herein are particularly suited for filtering liquid streams.

[0099] Exemplary liquid streams include, for example, the following: fuel, hydraulic oil, process water, air, diesel engine fluid (DEF), diesel engine lubricating oil, blow-by gas, and the like, and combinations thereof.

[0100] In some embodiments, a method of filtering a liquid stream may include passing a liquid stream containing contaminants through a nonwoven filtration medium and removing the contaminants from the liquid stream.

[0101] Exemplary Filtration Media Embodiments [Aspect 1] 1. A nonwoven filtration medium comprising: 25% to 85% by weight of bicomponent fibers having a fiber diameter in the range of 5 microns to 25 microns and a fiber length of 0.1 cm to 15 cm; 5% to 50% by weight of small filtration efficiency fibers having a fiber diameter of at least 0.1 micron and less than 1 micron; 10% to 50% by weight of high filtration efficiency fibers having a fiber diameter in the range of 1 micron to 5 microns; and 5% to 25% by weight of microfibrillated fibers, wherein a majority of the microfibrillated fibers comprise microfibrillated fibers having a transverse dimension of up to 4 microns, and the nonwoven filtration medium is substantially free of glass fibers. [Aspect 2] 2. The nonwoven filtration medium of claim 1, comprising: 25% to 75% by weight of the bicomponent fibers; 10% to 50% by weight of the low filtration efficiency fibers; 10% to 25% by weight of the high filtration efficiency fibers; or 10% to 25% by weight of the microfibrillated fibers; or a combination thereof. [Aspect 3]

[0023] Aspect 3. The nonwoven filtration media of aspect 1 or aspect 2, wherein the weight percentages are based on the bicomponent fibers, the low filtration efficiency fibers, the high filtration efficiency fibers, and the microfibrillated cellulose fibers. [Aspect 4] 4. The nonwoven fabric filtration medium of any one of claims 1-3, wherein the bicomponent fibers comprise a structural polymer portion and a thermoplastic binder polymer portion, the structural polymer portion having a melting point greater than the melting point of the binder polymer portion. [Aspect 5] 5. The nonwoven filtration media of embodiment 4, wherein the structural polymer portion of the bicomponent fibers has a melting point of at least 240°C and the binder polymer portion of the bicomponent fibers has a melting point of up to 115°C. [Aspect 6] 5. The nonwoven filtration medium of claim 4, wherein the structural polymer portion of the bicomponent fibers has a melting point of at least 240°C and the binder polymer portion of the bicomponent fibers has a melting point in the range of 100°C to 190°C. [Aspect 7] 7. The nonwoven fabric filtration medium of claim 6, wherein the binder polymer portion of the bicomponent fibers has a melting point in the range of 140°C to 160°C. [Aspect 8] Aspect 8. The nonwoven fabric filtration medium of any one of aspects 4-7, wherein the structural polymer portion is the core of the bicomponent fiber and the sheath is the thermoplastic binder polymer portion of the bicomponent fiber. [Aspect 9]

[0023] Aspect 9. The nonwoven filtration media of any of aspects 4-8, wherein the structural polymer portion comprises polyethylene terephthalate (PET) and the thermoplastic binder polymer portion comprises coPET. [Aspect 10] 10. The nonwoven fabric filtration medium of any one of embodiments 1-9, wherein the bicomponent fibers comprise first bicomponent fibers and second bicomponent fibers. [Aspect 11] 11. The nonwoven filtration medium of any one of embodiments 1-10, wherein the low filtration efficiency fibers have a fiber diameter of at least 0.4 microns and less than 1 micron. [Aspect 12] 12. The nonwoven fabric filtration medium of any one of the preceding aspects, wherein the low filtration efficiency fibers have a fiber diameter in the range of 0.6 microns to 0.8 microns. [Aspect 13] 13. The nonwoven filtration medium of any one of the preceding aspects, wherein the low filtration efficiency fibers have a fiber diameter of 0.7 microns. [Aspect 14] 14. The nonwoven fabric filtration medium of any one of aspects 1 to 13, wherein the low filtration efficiency fibers have a length in the range of 1 mm to 15 mm. [Aspect 15] 15. The nonwoven fabric filtration medium of any one of aspects 1-14, wherein the low filtration efficiency fibers comprise polyethylene terephthalate (PET). [Aspect 16] 16. The nonwoven fabric filtration medium of any one of aspects 1 to 15, wherein the high filtration efficiency fibers have a fiber diameter in the range of 2 microns to 4 microns. [Aspect 17] 17. The nonwoven fabric filtration medium of any one of aspects 1 to 16, wherein the high filtration efficiency fibers comprise polyethylene terephthalate (PET). [Aspect 18] 18. The nonwoven filtration medium of any one of embodiments 1-17, wherein a majority of the microfibrillated fibers have a lateral dimension of up to 2 microns. [Aspect 19] 19. The nonwoven fabric filtration medium of any one of the preceding aspects, wherein a majority of the microfibrillated fibers have transverse dimensions within the range of 0.5 microns to 1.5 microns. [Aspect 20] Aspect 20. The nonwoven fabric filtration medium of any one of aspects 1 to 19, wherein the microfibrillated fibers comprise microfibrillated cellulose fibers. [Aspect 21] 21. The nonwoven fabric filtration medium of any one of aspects 1 to 20, wherein the nonwoven fabric filtration medium has a solidity in the range of 5% to 15%. [Aspect 22] The nonwoven filtration medium is 24 g / m 2 ~100g / m 2 22. The nonwoven fabric filtration medium of any one of embodiments 1 to 21, having a basis weight in the range: [Aspect 23] 23. The nonwoven fabric filtration medium of any one of aspects 1 to 22, wherein the nonwoven fabric filtration medium has a pore size in the range of 0.5 microns to 20 microns. [Aspect 24] 24. The nonwoven filtration medium of any one of aspects 1-23, wherein the nonwoven filtration medium has a P95 / P50 ratio of at least 1.5 or at least 2. [Aspect 25] 25. The nonwoven filtration medium of any one of aspects 1-24, wherein the nonwoven filtration medium has a P95 / P50 ratio of up to 3. [Aspect 26] 26. The nonwoven fabric filtration medium according to any one of aspects 1 to 25, wherein the nonwoven fabric filtration medium has a thickness in the range of 0.12 mm to 1 mm. [Aspect 27] The nonwoven filtration media is resistant to filtration in 1 ft of water with 0.5 inches of water. 3 / ft 2 / min to 100ft in 0.5 inches of water 3 / ft 2 27. The nonwoven fabric filtration medium of any one of embodiments 1 to 26, having a permeability in the range of up to 1 / min. [Aspect 28] Aspect 28. The nonwoven fabric filtration medium of any one of aspects 1 to 27, wherein the nonwoven fabric filtration medium is substantially free of resin. [Aspect 29] 29. The nonwoven fabric filtration medium of any one of aspects 1 to 28, wherein the nonwoven fabric filtration medium is substantially free of glass fibers. [Aspect 30] 30. The nonwoven filtration medium of any one of the preceding aspects, wherein the low filtration efficiency fibers comprise polyethylene terephthalate (PET), and the PET of the low filtration efficiency fibers has a melting point of at least 250°C, at least 275°C, or at least 290°C. [Aspect 31] 31. The nonwoven filtration medium of any one of the preceding aspects, wherein the high filtration efficiency fibers comprise polyethylene terephthalate (PET), and the PET of the high filtration efficiency fibers has a melting point of at least 250°C, at least 275°C, or at least 290°C. [Aspect 32] 32. A method of filtering a liquid stream, the method comprising: passing a liquid stream containing contaminants through a nonwoven filtration medium, the nonwoven filtration medium comprising the nonwoven filtration medium of any one of Aspects 1-31; and removing the contaminants from the liquid stream. [Aspect 33] 33. The method of embodiment 32, wherein the liquid stream comprises fuel, hydraulic oil, process water, air, diesel engine fluid (DEF), diesel engine lubricating oil, or blow-by gas, or a combination thereof.

[0102] The following examples illustrate the present invention, with the understanding that the specific examples, materials, amounts, and procedures are to be interpreted broadly in accordance with the scope and spirit of the invention as set forth herein. [Example]

[0103] All reactants, starting materials, and solvents used in the following examples were purchased from commercial suppliers (e.g., Sigma Aldrich, St. Louis, MO) and used without further purification unless otherwise noted.

[0104] Preparation of media handsheets Handsheets were prepared by weighing the component fibers to achieve the required basis weight when formed into a 30 cm x 30 cm sheet. A FORMAX 12" x 12" stainless steel sheet mold (catalog number G-100, Adirondack Machine Corporation, Hudson Falls, NY) was used as the handsheet former, and a uniform nonwoven scrim layer with pores less than 100 μm was placed at the bottom of the former (a removable forming wire was not used). The former was then nearly filled with cold tap water, leaving room for adding 1.5 L of additional water. 1 mL of Tide HE laundry soap (Procter & Gamble, Cincinnati, OH) was added to the water in the handsheet former. To prepare the fibers, 1 L of cold tap water was added to a Vitamix blender along with 200 mL of 5% acetic acid in water. The weighed fibers were added to the blender and mixed at medium-low speed for 180 seconds. The contents of the blender were then added to a handsheet former, and the contents of the handsheet former were mixed to ensure uniform fiber distribution. Water was drained from the bottom of the handsheet former, allowing the fibers to form a sheet as they were collected on the nonwoven scrim. Water was removed from the sheet using vacuum suction on the wire side, and the handsheet (still on the scrim) was dried at 120°C for 10 minutes in a single-sided hotplate speed dryer (Model 135 Speed ​​Dryer, Emerson Apparatus, Gorham, ME). The sheet was removed (from the scrim) and allowed to cool to ambient conditions before use.

[0105] Media characterization Liquid filtration performance test (multi-pass) Using a circular flat sheet, the pressure drop at clean, media velocity, filtration capacity, and 4 μm Beta (β 4μm ) was calculated.

[0106] In the cases of Examples 2 and 3 The media was tested as described in ISO 16889:2008 (Hydraulic fluid power - Filters - Multi-pass method for evaluating filtration performance of a filter element), except that the hydraulic fluid was loaded using ISO Fine Test Dust instead of ISO Medium Test Dust. The media area was 0.0507 m 2 , the test flow rate was 2 L / min, and the test was carried out until the differential pressure at the end element was 200 kPa.

[0107] In the case of Example 4 The media was tested as described in ISO 16889:2008 (Hydraulic fluid power - Filters - Multi-pass method for evaluating the filtration performance of a filter element). The media area was 0.0507 m 2 The test flow rate was 16 L / min, and the test was run until the differential pressure at the end element was 320 kPa.

[0108] figure of merit Figure of Merit (FOM) is a measure of a filter media's performance and ability to impart a certain level of clarification to a stream using minimal energy.

[0109] FOM (unit: kPa -1 ) is calculated using the following formula: FOM=-ln(1 / β 4μm ) / (ΔP / media speed) ln(1 / β 4μm ) is β 4μm is the natural logarithm of the reciprocal of β 4μm(dimensionless), pressure drop (ΔP or dP) (units, kPa), and media velocity (units, mm / sec) are determined as described in the Liquid Filtration Performance Test section above.

[0110] Basis Weight, Basis Volume, Thickness, and Solidity The solidity (c) of a nonwoven layer (e.g., including a non-fine fiber layer or a composite layer including a fine fiber layer and a non-fine fiber layer) is calculated using the following formula: c=BW / ρZ where BW is the basis weight, ρ is the fiber density, and Z is the thickness of the media.

[0111] Caliper was measured according to TAPPI T411 om-15, entitled "Thickness (caliper) of paper, paperboard, and combined board;" using a foot pressure of 1.5 psi. Basis weight was measured using TAPPI T410 om-08, and the mass of the dry media (fiber and scrim) was measured using a 30 cm x 30 cm sample on the scrim.

[0112] Calculate the basis volume (BV=BW / Z), i.e., the basis weight divided by the thickness.

[0113] transparency At least 38 cm from the medium being tested 2 A sample of 1000 mm was cut out. The sample was mounted in a TEXTEST® FX 3310 (obtained from Textest AG, Schwerzenbach, Switzerland). Air was used to measure the permeability through the media, measured in cubic feet of air per square foot of media per minute (ft ). 3 air / ft 2 medium / minute), or cubic meters of air per square meter of medium per minute (m 3 air / m 2 media / min) was measured at a pressure drop of 0.5 inches of water (125 Pa).

[0114] Capillary flow porometry (pore size measurement) Pore ​​size measurements were performed by capillary flow porometry using continuous pressure scans on a Porometer 3G (Quanachrome Instruments, Boynton Beach, CA).

[0115] The method used silicone oil with a surface tension of 20.1 dynes / cm and a wetting contact angle of 0, and samples were tested in both wet and dry states (first dry, then wet). Samples with a 6 mm diameter were subjected to successive pressure scans selected to measure the majority of the cumulative pore size distribution, ranging from 2% to 98%.

[0116] Samples were tested under wet and dry conditions from low to high pressures. The airflow and sample pressure during the saturated portion of the test are commonly referred to as the wetting curve. 256 data points were collected across the pressure scan range for both the dry and wetting curves. Data points were collected at a rate of approximately 17 data points per minute across the entire scan. Tests were conducted at ambient conditions (e.g., 20°C to 25°C). No adjustments were made to the pore size refinement by applying empirical tortuosity and / or shape factors.

[0117] In a flow porometry test procedure, a series of pressure (typically plotted on the x-axis) and airflow (typically plotted on the y-axis) data for a dry sample and a set of pressure and airflow data for a saturated (wet) sample are collected. These two data sets are commonly referred to as the dry curve and the wet curve. That is, Drying curve=V dry = airflow through the dry sample as a function of pressure, Wetting curve = V wet = airflow through a saturated sample as a function of pressure.

[0118] Based on capillary theory, the pressure difference (ΔP) across the sample can be converted to pore diameter (d) using the Young-Laplace equation.

number

[0119] This transformation allows the definition of the drying and wetting curves as a function of pore size: Drying curve=V' dry = airflow through the dry sample as a function of diameter, Wetting curve = V' wet = airflow through a saturated sample as a function of diameter.

[0120] The cumulative flow pore size distribution (Q) is defined as the ratio of the wet curve to the dry curve as a function of pore size, where:

number

[0121] The cumulative distribution can be expressed as the increase in cumulative distribution from 0% to 100% or as the decrease in cumulative distribution from 100% to 0%. Pore size herein is defined from the increase in cumulative flow pore size distribution, where: Cumulative flow pore distribution increase = 1-Q(d) is.

[0122] To better define the points along this curve, we define various P(x%) values ​​that are equivalent to the corresponding pore diameter (d). P(x%)=d, where x%=1-Q(d).

[0123] Examples include, but are not limited to: P5 is the pore size with an increase in cumulative flow pore distribution of 5%. P10 is the pore size with an increase in cumulative flow pore distribution of 10%. P50 is the pore size with an increase in cumulative flow pore distribution of 50%. P90 is the pore size with an increase in cumulative flow pore distribution of 90%. P95 is the pore size with an increase of 95% of the cumulative flow pore distribution.

[0124] Where maximum pore size is reported, it was determined by detecting the bubble point using the automated bubble point (BP Auto Tolerance) method with a Porometer 3G (Quanachrome Instruments, Boynton Beach, CA). According to this method, the bubble point is detected after fluid begins to pass through the sample and three consecutive measurements show an increase of at least 1%. The bubble point is the value at the start of these three consecutive points.

[0125] Example 1 A glass-free filter medium containing 40 wt.% 14 μm diameter bicomponent fibers, 20 wt.% 0.7 μm diameter PET fibers, 20 wt.% 2.5 μm diameter PET fibers, and 20 wt.% 1 μm diameter microfibrillated rayon fibers was simulated using Geodict (Math2Market). A pictorial representation of the resulting medium is shown in Figure 1.

[0126] Example 2 The handsheets were then coated as described above with a 24 g / m 2 The 14 μm diameter bicomponent fiber (Advansa 271P) was mixed with varying amounts of 700 nm diameter PET fiber (TJ04BN, Teijin Fibers Limited, Osaka, Japan) (Figure 2, blue data points, blue trend line) or 24 g / m 2 14 μm diameter bicomponent fibers were prepared by mixing varying amounts of 700 nm diameter PET fiber, 1 μm diameter microfibrillated rayon fiber (Lyocell), and 2.5 μm diameter PET fiber (Teijin Fibers Ltd., Osaka, Japan) (Figure 2, pink data points, pink trend line), and β was measured to obtain β 4μm= 10,000. The results are shown in Figure 2. Varying amounts of 700 nm diameter PET fiber only were used to vary the basis weight. The amount of each fiber added is shown in Table 1.

[0127] [Table 1]

[0128] Extrapolating the collected data, we found that 24 g / m 2 From a medium containing bicomponent fibers of 14 μm diameter, 4μm To achieve =10,000, approximately 20 g / m 2 However, the addition of a 1 μm diameter microfibrillated rayon fiber and a 2.5 μm diameter PET fiber to the 700 nm diameter PET fiber and the 14 μm diameter bicomponent fiber results in a β 4μm To achieve 10,000, only about 12 g / m 2 PET fibers with a diameter of 700 nm would be sufficient.

[0129] These results were unexpected because, typically, smaller fibers are added to create high filtration efficiency media for liquid filtration. However, as seen in this example, the same filtration efficiency achieved by adding 700 nm diameter PET fibers to 14 μm diameter bicomponent fibers was achieved by removing some of these smaller fibers and replacing them with larger fibers (1 μm (1000 nm)-diameter microfibrillated rayon fibers and 2.5 μm (2500 nm)-diameter PET fibers).

[0130] Without being bound by theory, it is believed that the use of 1 μm diameter microfibrillated rayon fibers in combination with 2.5 μm diameter PET fibers is particularly beneficial. The 1 μm diameter microfibrillated rayon fibers are believed to provide higher tensile strength than the 2.5 μm diameter PET fibers without the microfibrillated rayon fibers. The 2.5 μm diameter PET fibers are believed to provide a more uniform pore structure than the microfibrillated rayon fibers without the 2.5 μm diameter PET fibers.

[0131] Example 3 For Captimax 190 SC (Ahlstrom) (Figure 3, "Base Layer") and for a combination of polyester meltblown (FF40 / 240 PBT, Ahlstrom) and Captimax 190 SC (Ahlstrom) (Figure 3, "Polyester Meltblown on Base Layer"), β was measured using ISO Fine test dust at a concentration of 40 mg / L. 4μm was measured.

[0132] Handsheets were prepared by blending 50 wt% of 14 μm diameter bicomponent fibers with 1 μm diameter microfibrillated rayon fibers (Lyocell) and 2.7 μm diameter PET fibers (TJ04BN, Teijin) in a wet-laid process (Figure 3, "DCI Glass-Free / Base Layer"). ISO Fine test dust was used at a concentration of 40 mg / L to measure the β 4μm The results are shown in Figure 3.

[0133] About Captimax Media β 4μm When measuring the filtration efficiency, variations in filtration efficiency were observed. Without being bound by theory, this is likely due to a lack of pore size uniformity. The presence of larger pores will result in a decrease in the observed filtration efficiency, but larger particles can be added until they fill the larger pores, at which point filtration efficiency increases again.

[0134] Example 4 As described above, handsheets were prepared by mixing co-PET / PET bicomponent fiber (TJ04CN, Teijin Limited, Tokyo, Japan), 2.7 μm diameter PET fiber (Teijin Limited, Tokyo, Japan), microfibrillated cellulose fiber (L-10-4, Engineered Fibers Technology, LLC, Shelton, CT), and 700 nm diameter PET fiber (Teijin Limited, Tokyo, Japan) in the ratios shown in Table 2A.

[0135] The physical properties (mass, thickness, permeability, basis weight, basis volume, and solidity) of the media so obtained were tested as described above, and the results are shown in Table 2B.

[0136] The pore size of the media so obtained was tested as described above, and the results are shown in Table 2C. Clean pressure drop, media velocity, filtration capacity, and 4 μm Beta (β 4μm ) were calculated as described above, and the results are shown in Table 2C.

[0137] Filtration efficiency (β 4μm ) was compared using the combined fiber mass percent (wt%) of microfibrillated rayon and 700 nm diameter PET fibers in each handsheet (Figure 5). These results suggest that increasing the combined fiber mass percent of these two fibers increases the filtration efficiency of the resulting filter media.

[0138] The P95 / P50 ratios of the resulting media were compared to the fiber weight percent (wt%) of microfibrillated rayon in each handsheet (Figure 5A) or the fiber weight percent (wt%) of 2.7 μm diameter PET fiber in each handsheet (Figure 5B). These results suggest that increasing the loading of microfibrillated rayon fiber results in more heterogeneous pore sizes (indicated by the higher P95 / P50 ratio with increasing fiber weight percent in Figure 5A), whereas increasing the loading of 2.7 μm diameter PET fiber results in more homogeneous pore sizes (indicated by the lower P95 / P50 ratio with increasing fiber weight percent in Figure 5B).

[0139] The figure of merit (FOM) of the resulting media was compared to the fiber weight percent (wt%) of microfibrillated rayon in each handsheet (FIG. 6A) or the fiber weight percent (wt%) of 2.7 μm diameter PET fiber in each handsheet (FIG. 6B). Increasing the fiber weight percent of 2.7 μm diameter PET fiber did not improve the FOM (because improved filtration efficiency would result in higher pressure drop) (FIG. 6B), whereas increasing the fiber weight percent of microfibrillated rayon resulted in a higher FOM (FIG. 6A), suggesting improved filtration efficiency without significantly increasing pressure drop.

[0140] [Table 2]

[0141] [Table 3]

[0142] [Table 4]

[0143] The complete disclosures of all patents, patent applications, and publications, as well as electronically available materials, cited herein are incorporated by reference. In the event of any inconsistency between the disclosure of this application and the disclosure of a document incorporated herein by reference, the disclosure of this application shall control. The foregoing detailed description and examples have been provided for clarity of understanding only. No unnecessary limitations should be construed therefrom. The invention is not limited to the exact details shown and described, for variations obvious to those skilled in the art will be encompassed within the invention defined by the claims.

Claims

1. 1. A nonwoven filtration medium comprising: 25% to 85% by weight of bicomponent fibers having a fiber diameter in the range of 5 microns to 25 microns and a fiber length of 0.1 cm to 15 cm; 5% to 50% by weight of low filtration efficiency fibers having a fiber diameter of at least 0.1 microns and less than 1 micron; 10% to 50% by weight of high filtration efficiency fibers having a fiber diameter in the range of 1 micron to 5 microns; and 5% to 25% by weight of microfibrillated fibers, the majority of which have a transverse dimension of up to 4 microns. Including, Substantially free of glass fibers, Non-woven filtration media.

2. 10. The nonwoven filtration media of claim 1, wherein the bicomponent fibers comprise a structural polymer portion and a thermoplastic binder polymer portion, the structural polymer portion having a melting point higher than the melting point of the binder polymer portion.

3. 3. The nonwoven filtration media of claim 2, wherein the structural polymer portion of the bicomponent fibers has a melting point of at least 240°C and the binder polymer portion of the bicomponent fibers has a melting point in the range of 100°C to 190°C.

4. The nonwoven filtration medium of any one of claims 1 to 3, wherein the low filtration efficiency fibers have a fiber diameter of at least 0.4 microns to less than 1 micron.

5. The nonwoven filtration medium of any one of claims 1 to 4, wherein the high filtration efficiency fibers have a fiber diameter in the range of 2 microns to 4 microns.

6. the low filtration efficiency fibers comprise PET; or the high filtration efficiency fibers comprise PET; or It's both. The nonwoven fabric filtration medium of any one of claims 1 to 5.

7. The nonwoven filtration medium of any one of claims 1 to 6, wherein the microfibrillated fibers comprise microfibrillated cellulose fibers.

8. The nonwoven filtration medium of any one of claims 1 to 7, wherein the nonwoven filtration medium has a solidity in the range of 5% to 15%.

9. The nonwoven fabric filtration medium has a thickness of 24 g / m ２ ~100g / m ２ The nonwoven filtration media of any one of claims 1 to 8, having a basis weight in the range of:

10. The nonwoven filtration medium of any one of claims 1 to 9, wherein the nonwoven filtration medium has a pore size in the range of 0.5 microns to 20 microns.

11. The nonwoven filtration medium of any one of claims 1 to 10, wherein the nonwoven filtration medium has a P95 / P50 ratio in the range of 1.5 to 3.

12. The nonwoven filtration medium of any one of claims 1 to 11, wherein the nonwoven filtration medium has a thickness in the range of 0.12 mm to 1 mm.

13. The nonwoven filtration media is resistant to filtration by 1 ft 2 with 0.5 inches of water. ３ / ft ２ / min to 100 ft in 0.5 in. of water ３ / ft ２ The nonwoven filtration medium of any one of claims 1 to 12, having a permeability in the range of up to 1000 / min.

14. The nonwoven fabric filtration medium of any one of claims 1 to 13, wherein the nonwoven fabric filtration medium is substantially free of resin.

15. The nonwoven fabric filtration medium of any one of claims 1 to 14, wherein the nonwoven fabric filtration medium does not contain glass fibers.

16. 1. A method for filtering a liquid stream, comprising: Passing a contaminant-laden liquid stream through a nonwoven filtration medium, wherein the nonwoven filtration medium comprises the nonwoven filtration medium of any one of claims 1 to 15; and removing said contaminants from said liquid stream. A method comprising:

17. 17. The method of claim 16, wherein the liquid stream comprises fuel, hydraulic oil, process water, air, diesel engine fluid (DEF), diesel engine lubricating oil, or blow-by gas, or a combination thereof.

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