Filter media

Abstract

The present disclosure describes a filter medium that is preferably free of glass or substantially free of glass. In some embodiments, the filter medium preferably exhibits capacity and efficiency that is comparable to or better than similar glass-containing filter media. The filter medium includes bicomponent fibers, efficiency fibers (e.g., PET fibers), and microfibillated fibers. The efficiency fibers include fibers having a fiber diameter in the range of 1 micron to 5 microns and fibers having a fiber diameter of at least 0.1 micron and less than 1 micron.

Description

[0001] Cross-references to related applications

[0002] This application claims the benefit of U.S. Provisional Application No. 63 / 004,926, filed April 3, 2020, and U.S. Provisional Application No. 63 / 081,143, filed September 21, 2020, the disclosures of which are incorporated herein by reference in their entirety. Background Technology

[0003] Filter media, such as those used for fuel filtration, typically include glass microfibers. However, there are concerns that during certain types of filtration, glass microfibers may be released from the filter media, causing environmental pollution, or, in the case of fuel filtration, causing damage to the internal combustion engine. Summary of the Invention

[0004] This disclosure describes a filter medium that is preferably substantially glass-free or glass-free. In some embodiments, when the filter medium is substantially glass-free or glass-free, it preferably exhibits capacity and efficiency comparable to or better than similar glass-containing filter media.

[0005] In one aspect, this disclosure provides a nonwoven filter medium comprising: 25 wt% to 85 wt% of bicomponent fibers having a fiber diameter in the range of 5 micrometers to 25 micrometers and a fiber length in the range of 0.1 cm to 15 cm; 5 wt% to 50 wt% of low-efficiency fibers having a fiber diameter of at least 0.1 micrometers and less than 1 micrometer; 10 wt% to 50 wt% of high-efficiency fibers having a fiber diameter in the range of 1 micrometer to 5 micrometers; and 5 wt% to 25 wt% of microfibrillated fibers, wherein most of the microfibrillated fibers have a transverse dimension of up to 4 micrometers; wherein the nonwoven filter medium is substantially free of glass fibers.

[0006] In some embodiments, the bicomponent fiber includes a structural polymer portion and a thermoplastic binder polymer portion, wherein the structural polymer portion has a higher melting point than the binder polymer portion. 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.

[0007] In some embodiments, the low-efficiency fiber has a fiber diameter of at least 0.4 micrometers to less than 1 micrometer.

[0008] In some embodiments, the high-efficiency fiber has a fiber diameter in the range of 2 micrometers to 4 micrometers.

[0009] In some embodiments, the low-efficiency fiber includes PET or the high-efficiency fiber includes PET; or both the low-efficiency fiber and the high-efficiency fiber include PET.

[0010] In some embodiments, microfibrillated fibers include microfibrillated cellulose fibers.

[0011] In some embodiments, the nonwoven filter media has a solidity in the range of 5% to 15%. In some embodiments, the nonwoven filter media has a solidity of 24 g / m³. 2 Up to 100 g / m 2 The basis weight is within the range. In some embodiments, the nonwoven filter media has a pore size in the range of 0.5 micrometers to 20 micrometers. In some embodiments, the nonwoven filter media has a P95 / P50 ratio in the range of 1.5 to 3. In some embodiments, the nonwoven filter media has a thickness in the range of 0.12 mm to 1 mm. In some embodiments, the nonwoven filter media has a thickness of 1 ft in 0.5 inches of water. 3 / ft 2 / min to 100 ft at 0.5 inches underwater 3 / ft 2 Permeability within the range of / min.

[0012] In some embodiments, the nonwoven filter media is substantially resin-free.

[0013] In some embodiments, the nonwoven filter media does not contain glass fibers.

[0014] In another aspect, this disclosure describes a method for filtering a liquid stream, the method comprising passing a liquid stream containing contaminants through a nonwoven filter medium and removing 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 leaks, or combinations thereof.

[0015] As used in this article, micron is equivalent to micrometer (µm).

[0016] As used in this article, “fiber” has an average fiber diameter of up to 100 micrometers.

[0017] As used herein, a "fiber" has an aspect ratio (i.e., the ratio of length to transverse dimension) greater than 3:1, and preferably greater than 5:1. For example, glass fibers typically have an aspect ratio greater than 100:1. In this context, "transverse dimension" refers to the width (in two dimensions) or diameter (in three dimensions) of the fiber. The term "diameter" refers either to the diameter of a circular cross-section of the fiber or to the maximum cross-sectional dimension of a non-circular cross-section of the fiber. The fiber length can be finite or infinite, depending on the desired outcome.

[0018] As used herein, "β ratio" or "β" refers to the ratio of upstream particles to downstream particles under steady-flow conditions (ISO 16889:2008), as illustrated in the examples. A higher filter efficiency results in a higher β ratio. The β ratio is defined as follows:

[0019]

[0020] in N d,U It is the upstream particle count per unit fluid volume for particles with a diameter of d or larger, and N d,D This is the downstream particle count per unit fluid volume for particles with a diameter of d or larger. If present, append a subscript to β (e.g., d () Indicates the particle size of the ratio being reported.

[0021] As used herein, unless otherwise indicated, the capillary flow porosimetry is used to determine the pore size (e.g., P5, P50, and P95) and the ratio of pore sizes (e.g., P95 / P50). The capillary flow porosimetry can be performed using a continuous pressure scan mode. Using silicone oil with a surface tension of 20.1 dynes / cm and a wetting contact angle of 0 can be useful as the wetting fluid. Samples can be initially tested in a dry state (changing from low pressure to high pressure) and then in a wet state (again changing from low pressure to high pressure). This test is typically performed under ambient temperature conditions (e.g., 20°C to 25°C). 256 data points can be collected over the entire pressure scan range of both the dry and wet methods. Typically, tortuosity factors and / or shape factors are not used (i.e., factors equal to 1 can be used for comparison with other test methods that use adjustment factors).

[0022] As used in this article, the value P( x% ) is when the wet curve equals the dry curve (100 - x The aperture calculated at )% is as determined using the methods described herein. Although a calculated value, this can be understood as representing a percentage of the total flow through the layer. x% passes through the point where an orifice of equal or smaller size is located. For example, P50 (average flow orifice size) represents the point where the wet curve is equal to half the dry curve, and can be considered as an orifice size such that 50% of the total flow through the layer passes through an orifice of equal or smaller size.

[0023] As used herein, “pressure drop” (also referred to herein as “dP” or “ΔP”) refers to the pressure (applied by a pump) required to force fluid through a filter or filter medium (before the addition of contaminants) at a specific fluid velocity. Unless otherwise stated, the pressure drop is the clean pressure drop (measured as described in ISO 16889:2008). Samples can be tested using a test flow rate of 16 L / min. Tests can be performed up to a terminal element differential pressure of 320 kPa.

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

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

[0026] Unless otherwise stated, any reference to standard methods (e.g., ASTM, TAPPI, etc.) refers to the most recent available version of that method at the time of submission of this disclosure.

[0027] The terms "preferred" and "ideally" refer to embodiments of the invention that may provide certain benefits in certain circumstances. However, other embodiments may also be preferred in the same or other circumstances. Furthermore, the description of one or more preferred embodiments does not imply that other embodiments are not useful, and is not intended to exclude other embodiments from the scope of the invention.

[0028] Where the term "comprising" and its variations appear in the specification and claims, these terms are not restrictive. Such terms should be understood to imply inclusion of the stated steps or elements or a group of steps or elements, but not to exclude any other steps or elements or any other group of steps or elements.

[0029] "Comprising of..." means including and limited to anything contained in the phrase "comprising of...". Therefore, the phrase "comprising of..." indicates that the listed element is necessary or mandatory, and other elements may not be present. "Substantially comprising..." means including any element listed in the phrase, and limited to other elements that do not impede or contribute to the function or role specified in this disclosure for the listed element. Therefore, the phrase "substantially comprising..." indicates that the listed element is necessary or mandatory, but other elements are optional and may or may not be present, depending on whether they substantially affect the function or role of the listed element.

[0030] Unless otherwise stated, “a type”, “the” and “at least one type” are used interchangeably and mean one type or more than one type.

[0031] As used herein, the term “or” is generally used in its usual sense, which includes “and / or”, unless the context clearly indicates otherwise.

[0032] The term “and / or” means one or all of the listed elements or any combination of two or more of the listed elements.

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

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

[0035] The term "in the range" (and similar statements) includes the endpoints of the stated range.

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

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

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

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

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

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

[0042] Figure 1 A graphical representation simulating a glass-free filter medium is shown, as further described in Example 1, which comprises 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. The simulation of the rayon fibers does not fully depict their bundled characteristics.

[0043] Figure 2 The test β value is shown, which was measured to determine the β of the handwritten sheet.4µm = 10,000. The hand-copied sheet was prepared as described in Example 2 and comprised 24 g / m² of 14 µm diameter bicomponent fibers (with varying amounts of 700 nm diameter PET fibers (square data points)) or 14 µm diameter bicomponent fibers (with varying amounts of 700 nm diameter PET fibers), 1 µm diameter microfibrillated rayon fibers (Lyocell), and 2.5 µm diameter PET fibers (circular data points). A trend line was calculated for each dataset using curve fitting in Excel.

[0044] Figure 3 The β value measured for the medium prepared as described in Example 3 is shown. 4µm .

[0045] Figure 4 The β-values ​​for microfiberized rayon and 700 nm PET in media with varying amounts of each fiber type are shown. 4µm As further described in Example 4.

[0046] Figure 5A P95 / P50 plots are shown for the percentage of fiber mass of microfibrillated rayon in media with different amounts of microfibrillated rayon, as further described in Example 4. Figure 5B P95 / P50 plots are shown for the percentage of fiber mass in media with different amounts of 2.7 µm diameter PET fibers, as further described in Example 4.

[0047] Figure 6A The quality factor (FOM) plotted for the percentage of fiber mass of microfibrillated rayon in media with different amounts of microfibrillated rayon is shown, as further described in Example 4. Figure 6B The FOM (Form of Metrics) for 0.7 µm diameter PET fibers in media with different amounts of 0.7 µm diameter PET fibers is shown as a percentage of fiber mass, as further described in Example 4. Detailed Implementation

[0048] This disclosure describes a filter medium that is preferably substantially glass-free or glass-free. In some embodiments, when the filter medium is substantially glass-free or glass-free, it preferably exhibits capacity and efficiency comparable to or better than similar glass-containing filter media.

[0049] Filter media

[0050] In one aspect, this disclosure describes a filter medium. This filter medium is a nonwoven filter medium. This nonwoven filter medium is substantially free of glass (including, for example, glass fibers). In some embodiments, the nonwoven filter medium does not contain glass.

[0051] In some embodiments, the nonwoven filter media comprises: bicomponent fibers; “small efficiency fibers”, wherein “small efficiency fibers” as used herein are fibers having a fiber diameter of at least 0.1 micrometers and less than 1 micrometer; “large efficiency fibers”, wherein “large efficiency fibers” as used herein are fibers having a fiber diameter in the range of 1 micrometer to 5 micrometers; and microfibrillated fibers.

[0052] In some embodiments, low-efficiency fibers or high-efficiency fibers, or both, preferably include polyethylene terephthalate (PET).

[0053] In an exemplary embodiment, the nonwoven filter medium comprises: 25 wt% to 85 wt% of bicomponent fibers having a fiber diameter in the range of 5 micrometers to 25 micrometers and a fiber length in the range of 0.1 cm to 15 cm; 5 wt% to 50 wt% of low-efficiency fibers; 10 wt% to 50 wt% of high-efficiency fibers; and 5 wt% to 25 wt% of microfibrillated fibers, wherein most of the microfibrillated fibers have a transverse dimension of up to 4 micrometers.

[0054] An exemplary embodiment is shown in Example 2. As further described in Example 2, including fibers having a fiber diameter of at least 0.1 micrometers and less than 1 micrometer (700 nm) and fibers having a fiber diameter in the range of 1 micrometer to 5 micrometers (2.5 µm) allows similar efficiencies (β) to be achieved while providing a more open structure that will prevent undesirable pressure drops. As shown in Example 3, these efficiencies can also be obtained without using fibers having a fiber diameter of at least 0.1 micrometers and less than 1 micrometer (see Example 3). Figure 3 However, such media are expected to be denser, resulting in an undesirable higher pressure drop (dP).

[0055] It is well known in the art that using smaller-sized fibers results in more efficient filter media. However, nonwoven filter media containing only bicomponent fibers and fibers with a fiber diameter of at least 0.1 micrometers and less than 1 micrometer will have very low strength, especially the strength of the 0.1-micrometer to 1-micrometer fiber matrix formed in the spaces between the larger bicomponent fibers. This makes it unsuitable for many applications, particularly those where the filter media is subjected to dynamic forces. While strength can be increased by including resin, the use of resin is undesirable because it fills the pores in the media (which would otherwise be used to collect contaminants) and because it increases the pressure drop.

[0056] As the results of Example 4 show, including increased amounts of microfibrillated fibers and fibers with a diameter of at least 0.1 micrometers and less than 1 micrometer (700 nm) improves efficiency (see Example 4). Figure 4 The use of increased amounts of microfibers leads to improved filter media performance, as indicated by the quality factor (FOM). The quality factor is a measure of the performance of the filter media and its ability to provide a certain level of clarification of the flow with the lowest energy used. Figure 6A Furthermore, the use of increased amounts of microfibrillated fibers increases fiber entanglement and thus the strength of the fiber matrix. Increased strength can also be achieved by using materials that can form hydrogen bonds, such as rayon and cellulose.

[0057] However, the use of increased amounts of microfibrillated fibers also leads to an increased P95 / P50 ratio ( Figure 5A This indicates that the uniformity of the medium pore size decreases with increasing amounts of microfibrillated fibers. In contrast, adding an increased amount of high-efficiency fibers (i.e., fibers with a diameter in the range of 1 to 5 micrometers) results in a decreased P95 / P50 ratio. Figure 5B This indicates that the uniformity of the medium pore size increases with the increase of the amount of high-efficiency fibers.

[0058] Therefore, it is necessary to balance the proportions of bicomponent fibers, low-efficiency fibers, high-efficiency fibers, and microfibrillated fibers to obtain glass-free media with desired efficiency, strength, and uniformity. For example, to improve uniformity, it may be desirable to increase the proportion of high-efficiency fibers. To improve efficiency, it may be desirable to increase the proportion of low-efficiency fibers.

[0059] In some embodiments, one or more fibers are selected or treated to alter the electrostatic charge of the medium. Charge typically includes layers of positive or negative charges trapped at or near the polymer surface, or a charge cloud stored in the polymer bulk. Charge may also include polarization charges that are frozen when the dipoles of the molecules align. Methods for subjecting materials to charge are well known to those skilled in the art. These methods include, for example, thermal methods, liquid contact methods, electron beam methods, plasma methods, and corona discharge methods.

[0060] bicomponent fibers

[0061] The filter media contains bicomponent fibers. Any suitable bicomponent fiber can be used, and the bicomponent fiber can be selected according to the intended use of the media.

[0062] In some embodiments, the filter media comprises at least 25 wt%, at least 30 wt%, at least 35 wt%, at least 40 wt%, at least 45 wt%, at least 50 wt%, at least 55 wt%, at least 60 wt%, at least 65 wt%, or at least 70 wt% of bicomponent fibers. In some embodiments, the filter media comprises a maximum of 30 wt%, a maximum of 35 wt%, a maximum of 40 wt%, a maximum of 45 wt%, a maximum of 50 wt%, a maximum of 55 wt%, a maximum of 60 wt%, a maximum of 65 wt%, a maximum of 70 wt%, a maximum of 75 wt%, or a maximum of 85 wt% of bicomponent fibers. In an exemplary embodiment, the filter media comprises 25 wt% to 85 wt% of bicomponent fibers. In another exemplary embodiment, the filter media comprises 25 wt% to 75 wt% of bicomponent fibers. In yet another exemplary embodiment, the filter media comprises 25 wt% to 70 wt% of bicomponent fibers. In another exemplary embodiment, the filter medium comprises 50 wt% bicomponent fibers.

[0063] In some embodiments, the bicomponent fiber has a fiber diameter of at least 1 micrometer, at least 5 micrometers, at least 10 micrometers, at least 15 micrometers, or at least 20 micrometers. In some embodiments, the bicomponent fiber has a fiber diameter of a maximum of 5 micrometers, a maximum of 10 micrometers, a maximum of 15 micrometers, a maximum of 20 micrometers, a maximum of 25 micrometers, or a maximum of 30 micrometers. In an exemplary embodiment, the bicomponent fiber has a fiber diameter in the range of 5 micrometers to 25 micrometers. In another exemplary embodiment, the bicomponent fiber has a fiber diameter of 14 micrometers.

[0064] 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 a maximum of 0.5 cm, a maximum of 1 cm, a maximum of 5 cm, a maximum of 10 cm, or a maximum of 15 cm. In an exemplary embodiment, the bicomponent fibers have a fiber length in the range of 0.1 cm to 15 cm. In another exemplary embodiment, the bicomponent fibers have a fiber length of 6 mm.

[0065] In some embodiments, the bicomponent fiber includes a structural polymer portion and a thermoplastic binder polymer portion, the structural polymer portion having a higher melting point than the binder polymer portion.

[0066] The structural polymer portion and the adhesive polymer portion can be made of any suitable material. For example, the structural polymer portion may include PET, and the adhesive polymer portion may include copolymerized PET (coPET). In other examples, the structural polymer portion may include PET, and the adhesive polymer portion may include polyethylene (PE), PET, nylon, polypropylene (PP), polytetrafluoroethylene (PTFE), polyethersulfone (PES), polyphenylene sulfide (PPS), meta-aramid, or para-aramid. In other examples, the adhesive polymer portion may include polyethylene (PE), polylactic acid (PLA), nylon, ethylene-vinyl alcohol (EVOH), polyvinyl chloride (PVC), polyvinylidene fluoride (PVDF) (e.g., Kynar), or any other polymer or modified polymer designed to have a lower melting temperature than the core structural polymer.

[0067] In some embodiments, the structural polymer portion is the core of the bicomponent fiber, and the thermoplastic adhesive polymer portion is the sheath of the bicomponent fiber.

[0068] In some embodiments, the structural polymer portion of the bicomponent fiber has a melting point of at least 240°C, and the adhesive polymer portion of the bicomponent fiber has a melting point of at most 115°C. An exemplary bicomponent fiber (in which the structural polymer portion has a melting point of at least 240°C and the adhesive polymer portion has a melting point of at most 115°C) is 271P, a 14 µm diameter fiber available from Advansa (Hamm, Germany).

[0069] In some embodiments, the structural polymer portion of the bicomponent fiber has a melting point of at least 240°C, and the adhesive polymer portion of the bicomponent fiber has a melting point in the range of 100°C to 190°C. In one exemplary embodiment, the structural polymer portion of the bicomponent fiber has a melting point of at least 240°C, and the adhesive polymer portion of the bicomponent fiber has a melting point in the range of 120°C to 170°C. In another exemplary embodiment, the structural polymer portion of the bicomponent fiber has a melting point of at least 240°C, and the adhesive polymer portion of the bicomponent fiber has a melting point in the range of 140°C to 160°C.

[0070] Exemplary bicomponent fibers (wherein the structural polymer portion has a melting point of at least 240°C and the binder polymer portion has a melting point in the range of 100°C to 190°C) are TJ04CN (with a binder polymer portion melting point of 110°C) and TJ04BN (with a binder polymer portion melting point of 150°C), both available from Teijin Fibers Limited, Osaka, Japan; 271P (with a binder polymer portion melting point of 110°C), available from Advansa GmbH, Hamm, Germany; and T-202 or T-217 (each with a binder polymer portion melting point of 180°C), both available from Fiber Innovation Technology, Inc. of Johnson City, TN.

[0071] In some embodiments, the bicomponent fiber may include a first bicomponent fiber and a second bicomponent fiber. In an exemplary embodiment, the bicomponent fiber may include a first bicomponent fiber (wherein the structural portion has a melting point of at least 240°C and the adhesive polymer portion has a melting point of at most 115°C) and a second bicomponent fiber (wherein the structural polymer portion has a melting point of at least 240°C and the adhesive polymer portion has a melting point in the range of 100°C to 190°C). For example, the bicomponent fiber may include Advansa 271P and TJ04BN.

[0072] Small efficiency fiber

[0073] The filter media contains “small efficiency fibers”, where “small efficiency fibers” as used herein are fibers with a fiber diameter of at least 0.1 micrometers and less than 1 micrometer.

[0074] In some embodiments, the low-efficiency fiber is preferably PET fiber. In some embodiments, the low-efficiency fiber may be substantially composed of PET. In some embodiments, the low-efficiency fiber may be composed of PET.

[0075] Alternatively or alternatively, low-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 meltable polymers.

[0076] In some embodiments, the filter media comprises at least 5 wt%, at least 10 wt%, at least 15 wt%, at least 20 wt%, at least 25 wt%, at least 30 wt%, at least 35 wt%, at least 40 wt%, or at least 45 wt% low-efficiency fibers. In some embodiments, the filter media comprises a maximum of 15 wt%, a maximum of 20 wt%, a maximum of 25 wt%, a maximum of 30 wt%, a maximum of 35 wt%, a maximum of 40 wt%, a maximum of 45 wt%, a maximum of 50 wt%, or a maximum of 55 wt% low-efficiency fibers. In an exemplary embodiment, the filter media comprises 5 wt% to 50 wt% low-efficiency fibers. In another exemplary embodiment, the filter media comprises 10 wt% to 50 wt% low-efficiency fibers. In yet another exemplary embodiment, the filter media comprises 10 wt% to 40 wt% low-efficiency fibers. In yet another exemplary embodiment, the filter media comprises 10 wt% to 25 wt% low-efficiency fibers.

[0077] In some embodiments, the low-efficiency fiber has a fiber diameter of at least 0.1 micrometer, at least 0.2 micrometer, at least 0.3 micrometer, at least 0.4 micrometer, at least 0.5 micrometer, at least 0.6 micrometer, or at least 0.7 micrometer. In some embodiments, the low-efficiency fiber has a fiber diameter of at most 0.7 micrometer, at most 0.8 micrometer, at most 0.9 micrometer, or less than 1 micrometer. For example, in an exemplary embodiment, the low-efficiency fiber has a fiber diameter of at least 0.4 micrometer and less than 1 micrometer. In another exemplary embodiment, the low-efficiency fiber has a fiber diameter in the range of 0.6 micrometer to 0.8 micrometer. In yet another exemplary embodiment, the low-efficiency fiber has a fiber diameter of 0.7 micrometer.

[0078] In this example, the low-efficiency fiber is a PET fiber with a fiber diameter of 0.7 micrometers.

[0079] In some embodiments, the low-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-efficiency fibers have a length of at most 10 mm, at most 11 mm, at most 12 mm, or at most 15 mm. In an exemplary embodiment, the low-efficiency fibers have a length in the range of 1 mm to 15 mm. In another exemplary embodiment, the low-efficiency fibers have a length in the range of 1 mm to 12 mm.

[0080] In some embodiments, when the low-efficiency fiber includes PET, the PET of the low-efficiency fiber preferably has a melting point of at least 250°C, more preferably at least 275°C, and even more preferably at least 290°C.

[0081] High-efficiency fibers

[0082] The filter media further includes “high-efficiency fibers”, wherein “high-efficiency fibers” as used herein are fibers having a fiber diameter in the range of 1 micrometer to 5 micrometers.

[0083] In some embodiments, the high-efficiency fiber is preferably PET fiber. In some embodiments, the high-efficiency fiber may be substantially composed of PET. In some embodiments, the high-efficiency fiber may be composed of PET.

[0084] Alternatively, high-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 meltable polymers.

[0085] In some embodiments, the filter medium comprises at least 10 wt%, at least 15 wt%, at least 20 wt%, at least 25 wt%, or at least 30 wt% high-efficiency fibers. In some embodiments, the filter medium comprises a maximum of 15 wt%, a maximum of 20 wt%, a maximum of 25 wt%, a maximum of 30 wt%, a maximum of 35 wt%, a maximum of 40 wt%, a maximum of 45 wt%, or a maximum of 50 wt% high-efficiency fibers. In an exemplary embodiment, the filter medium comprises 10 wt% to 50 wt% high-efficiency fibers. In another exemplary embodiment, the filter medium comprises 10 wt% to 40 wt% high-efficiency fibers. In yet another exemplary embodiment, the filter medium comprises 10 wt% to 25 wt% high-efficiency fibers.

[0086] In some embodiments, the high-efficiency fiber has a fiber diameter of at least 1 micrometer, at least 1.5 micrometers, at least 2 micrometers, at least 3 micrometers, or at least 4 micrometers. In some embodiments, the high-efficiency fiber has a fiber diameter of a maximum of 1.5 micrometers, a maximum of 2 micrometers, a maximum of 3 micrometers, a maximum of 4 micrometers, or a maximum of 5 micrometers. For example, in an exemplary embodiment, the high-efficiency fiber has a fiber diameter in the range of 2 micrometers to 4 micrometers. In another exemplary embodiment, the high-efficiency fiber has a fiber diameter in the range of 2 micrometers to 3 micrometers. In yet another exemplary embodiment, the high-efficiency fiber has a fiber diameter of 2.5 micrometers. In yet another exemplary embodiment, the high-efficiency fiber has a fiber diameter of 2.7 micrometers.

[0087] In this example, the high-efficiency fiber is PET fiber, which has a fiber diameter of 2.7 micrometers.

[0088] In some embodiments, the high-efficiency fiber has a length of at least 0.5 mm, at least 1 mm, or at least 1.5 mm. In some embodiments, the high-efficiency fiber has a length of at most 10 mm, at most 11 mm, at most 12 mm, or at most 15 mm. In an exemplary embodiment, the high-efficiency fiber has a length in the range of 1 mm to 15 mm. In another exemplary embodiment, the high-efficiency fiber has a length in the range of 1 mm to 12 mm.

[0089] In some embodiments, when the high-efficiency fiber includes PET, the PET of the high-efficiency fiber preferably has a melting point of at least 250°C, more preferably at least 275°C, and even more preferably at least 290°C.

[0090] Microfiber

[0091] Nonwoven filter media contain microfibrillated fibers. As used herein, microfibrillated fibers are fibers that have been processed to produce fibers with a higher surface area and branched structure than unprocessed fibers.

[0092] In some embodiments, the microfibrillated fiber may be a microfibrillated acrylic fiber, including, for example, fibrillated CFF fiber (available from Engineered Fiber Technology, Sheldon, Connecticut). In some embodiments, the microfibrillated fiber may be a microfibrillated cellulose fiber, including, for example, rayon such as Lyocell or Tencel. In some embodiments, the microfibrillated fiber may be a microfibrillated p-aramid fiber, including, for example, Twaron Pulp (Teijin Aramid, BV, Netherlands). In some embodiments, the microfibrillated fiber may be a microfibrillated liquid crystal polymer (LCP) fiber, including, for example, microfibrillated Vectran fiber (available from Engineered Fiber Technology, Sheldon, Connecticut). In some embodiments, the microfibrillated fiber may be a microfibrillated poly(p-phenylenebenzobisoxazole) (PBO) fiber, including, for example, fibrillated Zylon fiber (available from Engineered Fiber Technology, Sheldon, Connecticut).

[0093] In some embodiments, the filter medium comprises at least 5 wt%, at least 10 wt%, at least 15 wt%, at least 20 wt%, at least 25 wt%, or at least 30 wt% microfibrillated fibers. In some embodiments, the filter medium comprises a maximum of 15 wt%, a maximum of 20 wt%, a maximum of 25 wt%, a maximum of 30 wt%, a maximum of 35 wt% microfibrillated fibers, or a maximum of 40 wt% microfibrillated fibers. In an exemplary embodiment, the filter medium comprises 5 wt% to 40 wt% microfibrillated fibers. In another exemplary embodiment, the filter medium comprises 5 wt% to 25 wt% microfibrillated fibers. In another exemplary embodiment, the filter medium comprises 10 wt% to 40 wt% microfibrillated fibers. In yet another exemplary embodiment, the filter medium comprises 10 wt% to 25 wt% microfibrillated fibers. In yet another exemplary embodiment, the filter medium comprises 12.5 wt% or 25 wt% microfibrillated fibers.

[0094] In some embodiments, microfibrillated fibers comprise microfibrillated cellulose. As used herein, microfibrillated cellulose (MFC) refers to cellulose produced by G. Chinga-Carrasco. Nanoscale Research Letters [ Nano Research Fast Report The material defined in [ ], 2011; 6:417: "MFC materials may consist of: (1) nanofibers, (2) filamentous particles, (3) fiber fragments and (4) fibers. This implies that MFC is not necessarily synonymous with microfibers, nanofibers or any other cellulose nanostructures. However, properly manufactured MFC materials contain nanostructures, i.e., nanofibers, as the main component." The diameters of these components (or "lateral dimensions" for microfibrillated cellulose fibers) are reproduced in Table 1 of the same document and are as follows: (1) nanofibers (< 0.1 µm); (2) filamentous particles (< 1 µm); (3) fibers or fiber fragments (10 to 50 µm).

[0095] Furthermore, as used herein, the term “microfibrillated cellulose” does not include dry-milled cellulose (also known as micronized cellulose or fine cellulose) and does not include microcrystalline cellulose obtained by removing the amorphous portion through acid hydrolysis, as described in U.S. Patent No. 5,554,287.

[0096] In some embodiments, a majority (i.e., more than half) of the microfibrils have a lateral dimension (e.g., width in two dimensions) of up to 1 micrometer, up to 1.5 micrometers, up to 2 micrometers, up to 3 micrometers, or up to 4 micrometers. In some embodiments, a majority of the microfibrils have a lateral dimension of at least 0.5 micrometers or at least 0.7 micrometers. In an exemplary embodiment, a majority of the microfibrils have a lateral dimension in the range of 0.5 micrometers to 4 micrometers. In another exemplary embodiment, a majority of the microfibrils have a lateral dimension in the range of 0.5 micrometers to 1.5 micrometers. In yet another exemplary embodiment, a majority of the microfibrils have a lateral dimension of up to 2 micrometers.

[0097] In some embodiments, microfibrillated fibers are incorporated (i.e., distributed throughout) into a fiber medium to form filter media (also referred to herein as "filtration medium" or "filter medium").

[0098] Characteristics of nonwoven filter media

[0099] In some embodiments, the nonwoven filter media has a solidity of at least 2%, at least 3%, at least 4%, at least 5%, at least 6%, at least 7%, at least 8%, at least 9%, or at least 10%. In some embodiments, the nonwoven filter media has a solidity of a maximum of 5%, a maximum of 6%, a maximum of 7%, a maximum of 8%, a maximum of 9%, a maximum of 10%, a maximum of 11%, a maximum of 12%, a maximum of 13%, a maximum of 14%, a maximum of 15%, a maximum of 16%, a maximum of 17%, a maximum of 18%, a maximum of 19%, or a maximum of 20%. In exemplary embodiments, the nonwoven filter media has a solidity in the range of 5% to 15%. In some embodiments, the solidity is preferably measured as described in the examples.

[0100] In some embodiments, the nonwoven filter media has a density of at least 20 g / m². 2 ), at least 24 g / m 2 At least 25 g / m 2 At least 30 g / m 2 At least 35 g / m 2 At least 40 g / m 2 At least 50 g / m 2 At least 60 g / m 2 or at least 70g / m 2 The basis weight. In some embodiments, the nonwoven filter media has a maximum weight of 25 g / m³. 2 The maximum is 30 g / m 2The maximum is 35 g / m 2 The maximum is 40 g / m 2 The maximum is 50 g / m 2 The maximum is 60 g / m 2 The maximum is 70 g / m 2 The maximum is 75 g / m 2 The maximum is 80 g / m 2 The maximum is 85 g / m 2 The maximum is 90 g / m 2 The maximum is 95 g / m 2 The maximum is 100 g / m 2 or a maximum of 105 g / m 2 The basis weight. In an exemplary embodiment, the nonwoven filter media has a basis weight of 24 g / m³. 2 Up to 100 g / m 2 Basis weight within the range. In some embodiments, the basis weight is preferably measured using ASTM D646-13.

[0101] In some embodiments, the nonwoven filter medium has a pore size of at least 0.5 micrometers, at least 1 micrometer, at least 1.5 micrometers, at least 2 micrometers, at least 3 micrometers, at least 5 micrometers, or at least 10 micrometers. In some embodiments, the nonwoven filter medium has a pore size of a maximum of 5 micrometers, a maximum of 10 micrometers, a maximum of 15 micrometers, or a maximum of 20 micrometers. In an exemplary embodiment, the nonwoven filter medium has a pore size from 0.5 micrometers to 20 micrometers. In an exemplary embodiment, the nonwoven filter medium has a pore size from 2 micrometers to 15 micrometers. As used herein, pore size refers to the average flow pore size, calculated as described in ASTM F316-03.

[0102] In some embodiments, the nonwoven filter media has a P95 / P50 ratio of at least 1.5 or at least 2. In some embodiments, the nonwoven filter media has a P95 / P50 ratio of up to 3.

[0103] In some embodiments, the nonwoven filter media has a thickness of at least 0.1 mm, at least 0.12 mm, at least 0.15 mm, or at least 0.2 mm. In some embodiments, the nonwoven filter media has a thickness of a maximum of 0.2 mm, a maximum of 0.4 mm, a maximum of 0.5 mm, a maximum of 0.7 mm, or a maximum of 1 mm. In some embodiments, the thickness of the filter media is preferably measured using a foot pressure of 1.5 psi according to the TAPPI T411 om-15 test method.

[0104] In some embodiments, the nonwoven filter media has a minimum depth of 1 ft at 0.5 inches of water. 3 / ft2 / min, at least 5 ft underwater at 0.5 inches. 3 / ft 2 / min, or at least 10 ft underwater at 0.5 inches. 3 / ft 2 / min of permeability. In some embodiments, the nonwoven filter media has a maximum permeability of 10 ft at 0.5 inches of water. 3 / ft 2 / min, maximum 20ft at 0.5 inches underwater. 3 / ft 2 / min, maximum 50 ft at 0.5 inches underwater. 3 / ft 2 / min, maximum 75 ft at 0.5 inches underwater. 3 / ft 2 / min, or up to 100 ft at 0.5 inches of water. 3 / ft 2 The permeability is / min. In an exemplary embodiment, the nonwoven filter media has a permeability of 1 ft at 0.5 inches of water. 3 / ft 2 / min to 100 ft at 0.5 inches underwater 3 / ft 2 The permeability is within the range of / min. In another exemplary embodiment, the nonwoven filter media has a permeability of 10 ft at a depth of 0.5 inches underwater. 3 / ft 2 / min to 75 ft underwater at 0.5 inches 3 / ft 2 Permeability within the range of / min. In some embodiments, permeability is preferably measured according to ASTM D737-18.

[0105] In some embodiments, the nonwoven filter media is substantially resin-free. In some embodiments, the nonwoven filter media does not contain resin. At the time of the invention, resin was often used to maintain the spacing between fibers in the filter media and to prevent media instability. However, resin can clog the pores in the filter media, reducing the density of the filter media and thus its lifespan.

[0106] Without being bound by theory, it is believed that combining microfibrillated fibers with high-efficiency fibers (which have fiber diameters ranging from 1 to 5 micrometers) is particularly beneficial for making filter media virtually resin-free. Microfibrillated fibers are thought to provide greater tensile strength, which helps maintain fiber spacing. Furthermore, high-efficiency fibers are believed to provide a more uniform pore structure.

[0107] In some embodiments, the nonwoven filter media comprises bicomponent fibers ranging from 25 wt% to 85 wt%. Using less than 25 wt% bicomponent fibers is expected to produce media with insufficient strength, as the binder portion of the bicomponent fibers helps hold the media together during use. Using more than 85 wt% bicomponent fibers will result in media without sufficient additional fibers to provide the desired efficiency and uniform structure.

[0108] In some embodiments, the nonwoven filter media includes a small amount of low-efficiency fibers (having a fiber diameter of at least 0.1 micrometers and less than 1 micrometer) ranging from 5 wt% to 50 wt%. Using less than 5 wt% of low-efficiency fibers often results in unsatisfactory efficiencies (e.g., β-resistance). 4µm Medium greater than 10). Using low-efficiency fibers greater than 50 wt% will increase the pressure drop and often produce a weaker medium because the fibers do not come into contact with another type of fiber that will help keep them in the medium.

[0109] In some embodiments, the nonwoven filter media contains an amount of high-efficiency fibers (having a fiber diameter in the range of 1 to 5 micrometers) ranging from 10 wt% to 50 wt%. Using less than 10 wt% of high-efficiency fibers often results in media with irregular pore sizes. Using more than 50 wt% of high-efficiency fibers often results in media that do not contain enough low-efficiency fibers to achieve the desired efficiency, or do not contain enough bicomponent fibers to provide the strength required during use.

[0110] In some embodiments, the nonwoven filter media contains microfibrillated fibers in an amount ranging from 5 wt% to 25 wt%. Using less than 5 wt% of microfibrillated fibers often results in media with insufficient strength and low efficiency during use. Using more than 25 wt% of microfibrillated fibers often leads to irregular pore sizes (as indicated by a high P95 / P50 ratio).

[0111] In the past, low-melting-point PET fibers were sometimes used as a substitute for resin. However, these fibers melt during the manufacture of nonwoven filter media and, like resin, clog the pores in the filter media, reducing density and thus shortening its lifespan.

[0112] Method using filter media

[0113] The filter media described herein can be used in any method conceived by a person skilled in the art. In some embodiments, the filter media described herein are particularly well suited for filtering liquid streams.

[0114] Exemplary liquid flows may include, for example, fuel, hydraulic oil, process water, air, diesel engine fluid (DEF), diesel engine lubricating oil, leaks, and combinations thereof.

[0115] In some embodiments, a method of filtering a liquid stream may include passing a liquid stream containing contaminants through a nonwoven filter medium and removing the contaminants from the liquid stream.

[0116] Exemplary filter media

[0117] Aspect 1 is a nonwoven filter medium comprising: 25 wt% to 85 wt% of bicomponent fibers having a fiber diameter in the range of 5 micrometers to 25 micrometers and a fiber length in the range of 0.1 cm to 15 cm; 5 wt% to 50 wt% of low-efficiency fibers having a fiber diameter of at least 0.1 micrometers and less than 1 micrometer; 10 wt% to 50 wt% of high-efficiency fibers having a fiber diameter in the range of 1 micrometer to 5 micrometers; and 5 wt% to 25 wt% of microfibrillated fibers, wherein most of the microfibrillated fibers have a transverse dimension of a maximum of 4 micrometers; wherein the nonwoven filter medium is substantially free of glass fibers.

[0118] Aspect 2 is a nonwoven filter medium as described in aspect 1, comprising: 25 wt% to 75 wt% of the bicomponent fiber; 10 wt% to 50 wt% of the low-efficiency fiber; 10 wt% to 25 wt% of the high-efficiency fiber; or 10 wt% to 25 wt% of the microfibrillated fiber; or a combination thereof.

[0119] Aspect 3 is a nonwoven filter medium as described in aspect 1 or aspect 2, wherein the wt% is based on the total weight of the bicomponent fiber, the low-efficiency fiber, the high-efficiency fiber and the microfibrillated cellulose fiber.

[0120] Aspect 4 is a nonwoven filter medium as described in any one of aspects 1 to 3, wherein the bicomponent fiber comprises a structural polymer portion and a thermoplastic binder polymer portion, wherein the structural polymer portion has a higher melting point than the binder polymer portion.

[0121] Aspect 5 is a nonwoven filter medium as described in aspect 4, wherein the structural polymer portion of the bicomponent fiber has a melting point of at least 240°C, and the adhesive polymer portion of the bicomponent fiber has a melting point of at most 115°C.

[0122] Aspect 6 is a nonwoven filter medium as described in aspect 4, wherein the structural polymer portion of the bicomponent fiber has a melting point of at least 240°C, and the adhesive polymer portion of the bicomponent fiber has a melting point in the range of 100°C to 190°C.

[0123] Aspect 7 is a nonwoven filter medium as described in aspect 6, wherein the binder polymer portion of the bicomponent fiber has a melting point in the range of 140°C to 160°C.

[0124] Aspect 8 is a nonwoven filter medium as described in any one of aspects 4 to 7, wherein the structural polymer portion is the core of the bicomponent fiber and the sheath is the thermoplastic adhesive polymer portion of the bicomponent fiber.

[0125] Aspect 9 is a nonwoven filter medium as described in any one of aspects 4 to 8, wherein the structural polymer portion comprises polyethylene terephthalate (PET) and the thermoplastic adhesive polymer portion comprises coPET.

[0126] Aspect 10 is a nonwoven filter medium as described in any of the preceding aspects, wherein the bicomponent fiber comprises a first bicomponent fiber and a second bicomponent fiber.

[0127] Aspect 11 is a nonwoven filter medium as described in any of the preceding aspects, wherein the low-efficiency fibers have a fiber diameter of at least 0.4 micrometers and less than 1 micrometer.

[0128] Aspect 12 is a nonwoven filter medium as described in any of the preceding aspects, wherein the low-efficiency fiber has a fiber diameter in the range of 0.6 micrometers to 0.8 micrometers.

[0129] Aspect 13 is a nonwoven filter medium as described in any of the preceding aspects, wherein the low-efficiency fiber has a fiber diameter of 0.7 micrometers.

[0130] Aspect 14 is a nonwoven filter medium as described in any of the preceding aspects, wherein the low-efficiency fiber has a length in the range of 1 mm to 15 mm.

[0131] Aspect 15 is a nonwoven filter medium as described in any of the preceding aspects, wherein the low-efficiency fiber comprises polyethylene terephthalate (PET).

[0132] Aspect 16 is a nonwoven filter medium as described in any of the preceding aspects, wherein the high-efficiency fiber has a fiber diameter in the range of 2 micrometers to 4 micrometers.

[0133] Aspect 17 is a nonwoven filter medium as described in any of the preceding aspects, wherein the high-efficiency fiber comprises polyethylene terephthalate (PET).

[0134] Aspect 18 is a nonwoven filter medium as described in any of the preceding aspects, wherein most of the microfibrils have a transverse dimension of up to 2 micrometers.

[0135] Aspect 19 is a nonwoven filter medium as described in any of the preceding aspects, wherein most of the microfibrillated fibers have a transverse dimension in the range of 0.5 micrometers to 1.5 micrometers.

[0136] Aspect 20 is a nonwoven filter medium as described in any of the preceding aspects, wherein the microfibrillated fiber comprises microfibrillated cellulose fiber.

[0137] Aspect 21 is a nonwoven filter medium as described in any of the preceding aspects, wherein the nonwoven filter medium has a solidity in the range of 5% to 15%.

[0138] Aspect 22 is a nonwoven filter medium as described in any of the preceding aspects, wherein the nonwoven filter medium has a concentration of 24 g / m³. 2 Up to 100 g / m 2 Basis weight within the range.

[0139] Aspect 23 is a nonwoven filter medium as described in any of the preceding aspects, wherein the nonwoven filter medium has a pore size in the range of 0.5 micrometers to 20 micrometers.

[0140] Aspect 24 is a nonwoven filter medium as described in any of the preceding aspects, wherein the nonwoven filter medium has a P95 / P50 ratio of at least 1.5 or at least 2.

[0141] Aspect 25 is a nonwoven filter medium as described in any of the preceding aspects, wherein the nonwoven filter medium has a P95 / P50 ratio of up to 3.

[0142] Aspect 26 is a nonwoven filter medium as described in any of the preceding aspects, wherein the nonwoven filter medium has a thickness in the range of 0.12 mm to 1 mm.

[0143] Aspect 27 is a nonwoven filter medium as described in any of the preceding aspects, wherein the nonwoven filter medium has a filtration efficiency of 1 ft underwater at a depth of 0.5 inches. 3 / ft 2 / min to 100 ft at 0.5 inches underwater 3 / ft 2 Permeability within the range of / min.

[0144] Aspect 28 is a nonwoven filter medium as described in any of the preceding aspects, wherein the nonwoven filter medium is substantially resin-free.

[0145] Aspect 29 is a nonwoven filter medium as described in any of the preceding aspects, wherein the nonwoven filter medium is substantially free of glass fibers.

[0146] Aspect 30 is a nonwoven filter medium as described in any of the preceding aspects, wherein the low-efficiency fiber comprises polyethylene terephthalate (PET), and wherein the PET of the low-efficiency fiber has a melting point of at least 250°C, at least 275°C, or at least 290°C.

[0147] Aspect 31 is a nonwoven filter medium as described in any of the preceding aspects, wherein the high-efficiency fiber comprises polyethylene terephthalate (PET), and wherein the PET of the high-efficiency fiber has a melting point of at least 250°C, at least 275°C, or at least 290°C.

[0148] Aspect 32 is a method for filtering a liquid stream, the method comprising passing a liquid stream containing a contaminant through a nonwoven filter medium comprising any of the preceding aspects, and removing the contaminant from the liquid stream.

[0149] Aspect 33 is the method as described in aspect 32, wherein the liquid flow includes fuel, hydraulic oil, process water, air, diesel engine fluid (DEF), diesel engine lubricating oil, or leaks, or combinations thereof.

[0150] The present invention is illustrated by the following examples. It should be understood that specific examples, materials, quantities, and procedures should be interpreted broadly in accordance with the scope and spirit of the invention as set forth herein.

[0151] Example

[0152] All reagents, starting materials, and solvents used in the following examples were purchased from commercial suppliers (e.g., Sigma-Aldrich, St. Louis, Missouri) and, unless otherwise specified, can be used without further purification.

[0153] Preparation of media hand-made sheets

[0154] Hand-formed sheets were prepared by weighing the bulk fibers to achieve the target basis weight required for forming 30 cm x 30 cm sheets. A FORMAX 12" x 12" stainless steel sheet mold (catalog number G-100, Adirondack Machine Corporation, Hudson-Forth, NY) was used as the hand-formed sheet molder, and preparation was achieved by placing a uniform, loosely woven nonwoven fabric layer with pores less than 100 µm at the bottom of the molder (without using removable forming lines). The molder was then filled almost to full with cold tap water, leaving room for the addition of an additional 1.5 L of water. 1 mL of Tide HE laundry soap (Procter & Gamble, Cincinnati, OH) was added to the water in the hand-formed sheet molder. To prepare the fibers, 1 L of cold tap water was added to a Vitamix mixer along with 200 mL of a 5% acetic acid aqueous solution. The weighed fibers were added to the mixer and mixed at a medium-low speed for 180 seconds. The contents of the mixer are then added to the hand-forming sheet former, and the contents of the hand-forming sheet former are mixed to ensure uniform fiber distribution. Water is drained from the bottom of the hand-forming sheet former, allowing the fibers to form a sheet as they are collected on the nonwoven sparse fabric. Water is removed from the sheet using vacuum suction on the line side, and the hand-formed sheet (still on the sparse fabric) is dried for 10 minutes at 120°C in a single-sided hot plate rapid dryer (Type 135 rapid dryer, Emerson Apparatus, Golham, Maine). The sheet (from the sparse fabric) is removed and allowed to cool to ambient conditions before use.

[0155] Medium characterization

[0156] Liquid filtration performance test (passed multiple times)

[0157] Cleaning pressure drop, medium velocity, capacity, and 4 µm β (β 4µm The calculation is performed using a circular flat plate as described below.

[0158] For examples 2 and 3

[0159] The test medium is 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 is loaded with ISO fine test dust instead of ISO medium test dust. The medium area is 0.0507 m². 2The test flow rate was 2 L / min, and the test was conducted up to a terminal element pressure difference of 200 kPa.

[0160] For example 4

[0161] The test medium is as described in ISO 16889:2008 (Hydraulic filters - Multiple-pass method for evaluating the filtration performance of filter elements). The medium area is 0.0507 m². 2 The test flow rate was 16 L / min, and the test was conducted up to a terminal element pressure differential of 320 kPa.

[0162] Quality Factor

[0163] The quality factor (FOM) is a measure of the performance of the filter media and its ability to provide a certain level of clarification of the flow with the lowest energy required.

[0164] Calculate FOM (in kPa) using the following formula. -1 count):

[0165] FOM = -ln(1 / β 4µm ) / (ΔP / medium velocity).

[0166] ln(1 / β 4µm ) is 1 divided by β 4µm The natural logarithm of β. β was determined as described in the liquid filtration performance testing section above. 4µm (Unitless), pressure drop (ΔP or dP) (in kPa) and medium velocity (in (mm / sec)).

[0167] Basis weight, reference volume, thickness and solidity

[0168] The solidity (c) of nonwoven layers (including, for example, non-fiber layers or composites comprising both fiber and non-fiber layers) is calculated using the following equation:

[0169] c = BW / ρZ.

[0170] Where BW is the basis weight, ρ is the fiber density, and Z is the thickness of the medium.

[0171] Thickness was measured according to TAPPI T411 om-15, titled "Thickness (caliper) of paper, paperboard, and combined board"; foot pressure of 1.5 psi was used. Basis weight was measured using TAPPI T410 om-08, where the mass of dry media (fiber and sparse cloth) was measured using a 30 cm × 30 cm sample on sparse cloth.

[0172] The base volume (BV = BW / Z) is calculated by dividing the base weight by the thickness.

[0173] Permeability

[0174] Cut at least 38 cm from the medium to be tested. 2 The sample was mounted on a Textest® FX 3310 (obtained from Textest AG, Schwerzenbach, Switzerland). The permeability through the medium was measured using air, specifically cubic feet of air per minute per square foot of medium. 3 air / ft 2 Medium / min) or cubic meters of air per minute per square meter of medium (m³) 3 air / m 2 The medium (min) was measured at a pressure drop of 0.5 inches (125 Pa) of water.

[0175] Capillary flow porosity method (pore size measurement)

[0176] Pore ​​size measurements were performed using a continuous pressure scan on a Porometer 3G (Quanachrome Instruments, Boynton Beach, CA) via capillary flow porosity method. This method used silicone oil with a surface tension of 20.1 dynes / cm and a wetting contact angle of 0°, and tested samples in both wet and dry states (dry first, then wet). Samples with a diameter of 6 mm were subjected to the selected continuous pressure scan to measure most of the cumulative pore size distribution within the range of 2% to 98%.

[0177] The sample was tested from low to high pressure in both wet and dry conditions. The airflow rate and sample pressure from the test saturation section are commonly referred to as the wet profile. 256 data points were collected over the pressure scan range of both the dry and wet profiles. Data points were collected throughout the scan at a rate of approximately 17 data points per minute. The test was conducted under ambient conditions (e.g., 20°C to 25°C). No empirical tortuosity factor and / or shape factor were applied to adjust the orifice diameter definition.

[0178] The flow porosity method testing procedure collects a set of pressure (typically plotted on the x-axis) and airflow rate (typically plotted on the y-axis) data for a dry sample, and a set of pressure and airflow rate data for a saturated (wet) sample. These two sets of data are commonly referred to as the dry profile and the wet profile. That is:

[0179]

[0180] Based on capillary theory, the pressure (ΔP) of the entire sample can be converted into the pore size (d) using the Young-Laplace formula.

[0181]

[0182] This conversion allows the dry and wet curves to be defined as functions of the aperture. That is:

[0183]

[0184] 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.

[0185]

[0186] The cumulative distribution can be represented as an increasing cumulative distribution from 0% to 100%, or as a decreasing cumulative distribution from 100% to 0%. The orifice size in this document is defined by the increasing cumulative flow orifice size distribution.

[0187]

[0188] To better identify points along the curve, this document defines various P(x%) values ​​equal to the corresponding aperture (d).

[0189] P(x%) = d, where x% = 1 - Q(d).

[0190] Examples include, but are not limited to, the following.

[0191] P5 is the orifice diameter with an increasing cumulative flow distribution of 5%.

[0192] P10 is the orifice diameter with an increasing cumulative flow rate distribution of 10%.

[0193] P50 is the orifice diameter with an incremental cumulative flow distribution of 50%.

[0194] P90 is an orifice diameter with an increasing cumulative flow rate distribution of 90%.

[0195] P95 is an orifice diameter with an incremental cumulative flow orifice distribution of 95%.

[0196] When reporting the maximum pore size, it was determined using an automated bubble point (BP Automated Tolerance) method, detected by using a Porometer 3G (Kunta Instruments, Boynton Beach, CA). According to this method, the bubble point is detected after the fluid begins to flow through the sample, and increases by at least 1% after three consecutive measurements. The bubble point is the value at the beginning of this three-point sequence.

[0197] Example 1

[0198] Geodict (Math2Market) was used to simulate a glass-free filter medium comprising 40 wt% bicomponent fibers with a diameter of 14 µm, 20 wt% PET fibers with a diameter of 0.7 µm, 20 wt% PET fibers with a diameter of 2.5 µm, and 20 wt% microfibrillated rayon fibers with a diameter of 1 µm. A graphical representation of the resulting medium is shown below. Figure 1 middle.

[0199] Example 2

[0200] As described above, by mixing 24 g / m² of 14 µm diameter bicomponent fiber (Advansa 271P) with varying amounts of 700 nm diameter PET fiber (TJ04BN, Teijin Fibers Co., Ltd., Osaka, Japan) Figure 2 (Blue data points, blue trend lines) or by mixing 24 g / m² bicomponent fibers with 14 µm diameter bicomponent fibers with varying amounts of 700 nm diameter PET fibers, 1 µm diameter microfibrillated rayon fibers (lyocell), and 2.5 µm diameter PET fibers (Teijin Fibers Co., Ltd., Osaka, Japan). Figure 2 (Pink data points, pink trend line) were used to prepare handwritten sheets, and β was measured to determine β. 4µm = 10,000. The results are shown in Table 2. Different amounts of 700 nm diameter PET fibers were used alone to provide different basis weights. The amount of each fiber added is shown in Table 1.

[0201] Table 1

[0202]

[0203] Extrapolating from the collected data, it is expected that β will be achieved from a medium containing bicomponent fibers with a diameter of 24 g / m² and 14 µm. 4µm = 10,000 would require approximately 20 g / m² of 700 nm diameter PET fibers. However, when microfibrillated rayon fibers with a diameter of 1 µm and PET fibers with a diameter of 2.5 µm are added to 700 nm diameter PET fibers and 14 µm diameter bicomponent fibers, only approximately 12 g / m² of 700 nm diameter PET fibers would be needed to achieve β. 4µm = 10,000.

[0204] These results were unexpected, as typically, adding smaller fibers is necessary to create high-efficiency media for liquid filtration. However, as this example demonstrates, the same efficiency achieved by adding 700 nm diameter PET fibers to a 14 µm diameter bicomponent fiber was accomplished by removing some of these smaller fibers and replacing them with larger (1 µm (1000 nm)) diameter microfibrillated rayon fibers and 2.5 µm (2500 nm) diameter PET fibers.

[0205] Without being bound by theory, it is believed that combining 1 µm diameter microfibrillated rayon fibers with 2.5 µm diameter PET fibers is particularly beneficial. The 1 µm diameter microfibrillated rayon fibers are thought to offer greater tensile strength compared to using 2.5 µm diameter PET fibers without microfibrillated rayon fibers. The 2.5 µm diameter PET fibers are thought to offer a more uniform pore structure compared to using microfibrillated rayon fibers without 2.5 µm diameter PET fibers.

[0206] Example 3

[0207] For Captimax 190 SC (Ahlstrom) ( Figure 3 "Base layer", and for combinations of meltblown polyester (FF40 / 240 PBT, Auslon) and Captimax 190 SC (Auslon) Figure 3 "Meltblown polyester on a base layer", β was measured using ISO fine test dust at a concentration of 40 mg / L. 4µm .

[0208] In the wet web forming process, hand-made sheets are prepared by mixing 50 wt% bicomponent fibers with a diameter of 14 µm, microfibrillated rayon fibers (lyocell) with a diameter of 1 µm, and PET fibers (TJ04BN, Teijin) with a diameter of 2.7 µm. Figure 3 "Does not contain DCI glass on the substrate"; β was measured using ISO fine test dust at a concentration of 40 mg / L. 4µm The results are shown in Table 3.

[0209] When measuring the β of Captimax medium 4µm Variable efficiency was observed. Not wanting to be bound by theory, this could be due to the lack of uniform pore size. The presence of larger pores caused a decrease in efficiency observed when larger particles were added, until those larger particles filled the larger pores, at which point the efficiency increased again.

[0210] Example 4

[0211] As described above, hand-made sheets were prepared by mixing co-PET / PET bicomponent fibers (TJ04CN, Teijin Ltd., Tokyo, Japan), PET fibers with a diameter of 2.7 µm (Teijin Ltd., Tokyo, Japan), microfibrillated cellulose fibers (L-10-4, Engineered Fibers Technology LLC, Shelton, CT, Connecticut) and PET fibers with a diameter of 700 nm (Teijin Ltd., Tokyo, Japan) in the proportions shown in Table 2A.

[0212] The physical properties of the medium obtained by testing as described above (mass, thickness, permeability, basis weight, reference volume and solidity) are shown in Table 2B.

[0213] The pore size of the medium was tested as described above, and the results are shown in Table 2C. The cleaning pressure drop, medium velocity, capacity, and 4 µm β (β) were calculated as described above. 4µm The results are shown in Table 2C.

[0214] Efficiency (β) 4µm The combined fiber mass percentage (wt%) of microfiberized rayon and 700 nm diameter PET fibers in each hand-coated sheet was compared (Figure 5). These results indicate that increasing the combined fiber mass percentage of these two fibers improves the efficiency of the resulting filter media.

[0215] The P95 / P50 ratio of the resulting medium was compared with the percentage of microfibrillated rayon fibers (wt%) in each hand-coated sheet. Figure 5A ), or compare with the fiber mass percentage (wt%) of PET fibers with a diameter of 2.7 µm in each hand-coated sheet ( Figure 5B These results indicate that adding more microfibrillated rayon fibers leads to more uneven pore sizes (e.g., Figure 5A As the fiber mass percentage increases, the P95 / P50 ratio increases (as shown in the figure), while adding more 2.7 µm diameter PET fibers results in a more uniform pore size (e.g., Figure 5B As the percentage of fiber mass increases, the P95 / P50 ratio decreases (as shown in the figure).

[0216] The quality factor (FOM) of the resulting medium was compared with the percentage of microfibrillated rayon fibers (wt%) in each hand-made sheet. Figure 6A ), or compare with the fiber mass percentage (wt%) of PET fibers with a diameter of 2.7 µm in each hand-coated sheet ( Figure 6B Although increasing the fiber mass percentage of PET fibers with a diameter of 2.7 µm does not improve FOM ( Figure 6B), because increased efficiency leads to higher pressure drop, but increasing the fiber mass percentage of microfiber rayon increases FOM (Flat Form Factor). Figure 6A This indicates that efficiency was improved without a corresponding increase in pressure drop.

[0217]

[0218]

[0219]

[0220] All disclosures of patents, patent applications, publications, and materials available electronically in connection with this application are incorporated herein by reference. In the event of any discrepancy between the disclosures in this application and those in any other document incorporated herein by reference, the disclosures in this application shall prevail. The detailed descriptions and examples above are provided for clarity only and should not be construed as unnecessarily limiting. The invention is not limited to the precise details shown and described, and variations that will be apparent to those skilled in the art will be included within the scope of the invention as defined by the claims.

Claims

1. A nonwoven filter medium comprising: 25 wt% to 75 wt% of bicomponent fibers, the bicomponent fibers having a fiber diameter in the range of 5 micrometers to 25 micrometers and a fiber length in the range of 0.1 cm to 15 cm; 5 wt% to 50 wt% of low-efficiency fibers, wherein the low-efficiency fibers have a fiber diameter of at least 0.1 micrometer and less than 1 micrometer; 10 wt% to 50 wt% high-efficiency fibers, wherein the high-efficiency fibers have a fiber diameter in the range of 1 micrometer to 5 micrometers; as well as 5 wt% to 25 wt% of microfibrils, wherein most of the microfibrils have a transverse dimension of up to 4 micrometers; The nonwoven filter media described therein is substantially free of glass fibers.

2. The nonwoven filter medium as described in claim 1, wherein, The bicomponent fiber comprises a structural polymer portion and a thermoplastic binder polymer portion, wherein the structural polymer portion has a higher melting point than the binder polymer portion.

3. The nonwoven filter medium as described in claim 2, wherein, The structural polymer portion of the bicomponent fiber has a melting point of at least 240°C, and the adhesive polymer portion of the bicomponent fiber has a melting point in the range of 100°C to 190°C.

4. The nonwoven filter medium as described in claim 1, wherein, The low-efficiency fiber has a fiber diameter of at least 0.4 micrometers to less than 1 micrometer.

5. The nonwoven filter medium as described in claim 1, wherein, The high-efficiency fiber has a fiber diameter in the range of 2 micrometers to 4 micrometers.

6. The nonwoven filter medium as described in claim 1, in, The low-efficiency fiber includes PET; or The high-efficiency fiber includes PET; or Both.

7. The nonwoven filter medium as described in claim 1, wherein, The microfibrillated fibers include microfibrillated cellulose fibers.

8. The nonwoven filter medium as described in claim 1, wherein, The nonwoven filter medium has a solidity in the range of 5% to 15%.

9. The nonwoven filter medium as described in claim 1, wherein, The nonwoven filter medium has a concentration of 24 g / m³. 2 Up to 100 g / m 2 Basis weight within the range.

10. The nonwoven filter medium as described in claim 1, wherein, The nonwoven filter medium has a pore size in the range of 0.5 micrometers to 20 micrometers.

11. The nonwoven filter medium as described in claim 1, wherein, The nonwoven filter media has a P95 / P50 ratio in the range of 1.5 to 3.

12. The nonwoven filter medium as described in claim 1, wherein, The nonwoven filter medium has a thickness in the range of 0.12 mm to 1 mm.

13. The nonwoven filter medium as described in claim 1, wherein, The nonwoven filter media has a filtration efficiency of 1 ft underwater at a depth of 0.5 inches. 3 / ft 2 / min to 100 ft at 0.5 inches underwater 3 / ft 2 Permeability within the range of / min.

14. The nonwoven filter medium as described in claim 1, wherein, The nonwoven filter media is essentially resin-free.

15. The nonwoven filter medium as described in claim 1, wherein, The nonwoven filter media does not contain glass fibers.

16. A method for filtering a liquid stream, the method comprising: A liquid containing contaminants is passed through a nonwoven filter medium, said nonwoven filter medium comprising any one of claims 1 to 15, and Remove the contaminants from the liquid stream.

17. The method of claim 16, wherein, The liquid flow includes fuel, hydraulic oil, process water, air, diesel engine fluid (DEF), diesel engine lubricating oil, or leaks, or combinations thereof.

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