WO2018017937A1 - Milieux de filtration multicouches contenant des électrets - Google Patents

Milieux de filtration multicouches contenant des électrets Download PDF

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Publication number
WO2018017937A1
WO2018017937A1 PCT/US2017/043249 US2017043249W WO2018017937A1 WO 2018017937 A1 WO2018017937 A1 WO 2018017937A1 US 2017043249 W US2017043249 W US 2017043249W WO 2018017937 A1 WO2018017937 A1 WO 2018017937A1
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WO
WIPO (PCT)
Prior art keywords
equal
layer
less
filter media
fibers
Prior art date
Application number
PCT/US2017/043249
Other languages
English (en)
Inventor
Sudheer Jinka
David T. Healey
Mark A. GALLIMORE
Original Assignee
Hollingsworth & Vose Company
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from US15/217,718 external-priority patent/US20180001247A1/en
Application filed by Hollingsworth & Vose Company filed Critical Hollingsworth & Vose Company
Priority to CN201780044830.6A priority Critical patent/CN109475798A/zh
Priority to EP17831940.6A priority patent/EP3487602A4/fr
Publication of WO2018017937A1 publication Critical patent/WO2018017937A1/fr

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D39/00—Filtering material for liquid or gaseous fluids
    • B01D39/14—Other self-supporting filtering material ; Other filtering material
    • B01D39/16—Other self-supporting filtering material ; Other filtering material of organic material, e.g. synthetic fibres
    • B01D39/1607—Other self-supporting filtering material ; Other filtering material of organic material, e.g. synthetic fibres the material being fibrous
    • B01D39/1623—Other self-supporting filtering material ; Other filtering material of organic material, e.g. synthetic fibres the material being fibrous of synthetic origin
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2239/00—Aspects relating to filtering material for liquid or gaseous fluids
    • B01D2239/04—Additives and treatments of the filtering material
    • B01D2239/0435—Electret
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2239/00—Aspects relating to filtering material for liquid or gaseous fluids
    • B01D2239/06—Filter cloth, e.g. knitted, woven non-woven; self-supported material
    • B01D2239/065—More than one layer present in the filtering material
    • B01D2239/0659—The layers being joined by needling
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2239/00—Aspects relating to filtering material for liquid or gaseous fluids
    • B01D2239/12—Special parameters characterising the filtering material
    • B01D2239/1258—Permeability

Definitions

  • the present embodiments relate generally to filter media and methods for filtering gas streams, and specifically, to filter media having efficiency stability and/or good performance characteristics such as low resistance.
  • Filter elements can be used to remove contamination in a variety of applications.
  • Such elements can include a filter media which may be formed of a web of fibers.
  • the fiber web provides a porous structure that permits gas (e.g., air) to flow through the media.
  • Contaminant particles e.g., dust particles, soot particles
  • the filter media may be designed to have different performance characteristics.
  • Filter media are generally provided.
  • the subject matter of this application involves, in some cases, interrelated products, alternative solutions to a particular problem, and/or a plurality of different uses of structures and compositions.
  • a series of filter media are provided.
  • a filter media comprises a first layer comprising a plurality of fibers, wherein the first layer comprises a fluorinated species, and a second layer adjacent the first layer.
  • the first layer has a first value of a thickness over instantaneous resistance of the first layer
  • the second layer has a second value of a thickness over instantaneous resistance of the second layer
  • the ratio of the second value to the first value is less than or equal to 20.
  • the filter media has an initial efficiency of greater than or equal to 95% .
  • a filter media comprises a first layer comprising a plurality of fibers, wherein the first layer comprises a fluorinated species, and a second layer adjacent the first layer.
  • the first layer has a value of thickness over instantaneous resistance of the first layer of greater than or equal to 2 mils/mmH 2 0 and less than or equal to 50 mils/mm H 2 0.
  • the second layer has a value of thickness over instantaneous resistance of the second layer of greater than or equal to 20 mils/mmH 2 0 and less than or equal to 150 mils/mm H 2 0.
  • a filter media comprises a first layer comprising a plurality of fibers and a second layer adjacent the first layer.
  • the first layer has a first value of a thickness over instantaneous resistance of the first layer
  • the second layer has a second value of a thickness over instantaneous resistance of the second layer
  • the ratio of the second value to the first value is less than or equal to 20.
  • the filter media has an initial efficiency of greater than or equal to 95%.
  • a filter media comprises a first layer comprising a plurality of fibers and a second layer.
  • the first layer has a first value of a basis weight over air permeability of the first layer
  • the second layer has a second value of a basis weight over air permeability of the second layer
  • the ratio of the first value to the second value is greater than or equal to 0.01 and less than or equal to 5 (e.g., greater than or equal to 0.01 and less than or equal to 4).
  • the first layer has a basis weight of less than or equal to 20 g/m and the plurality of fibers of the first layer have an average fiber diameter of greater than or equal to 1 micron and less than or equal to 8 microns.
  • the second layer is charged and the second layer has a basis weight of greater than or equal to 30 g/m 2 and less than or equal to 85 g/m 2.
  • FIG. 1 is a schematic diagram showing a cross-section of a filter media according to one set of embodiments
  • FIG. 2 is a schematic diagram showing a cross-section of a filter media according to one set of embodiments
  • FIG. 3 is a schematic diagram showing a cross-section of a filter media according to one set of embodiments
  • FIG. 4 is a schematic diagram showing a cross-section of a filter media according to one set of embodiments
  • FIG. 5 is a schematic diagram showing a cross-section of a filter media according to one set of embodiments
  • FIG. 6 is a plot of thickness over instantaneous resistance ratio of two layers of a filter media, according to one set of embodiments.
  • FIG. 7 is a plot of air permeability versus basis weight over air permeability ratio of a filter media, according to one set of embodiments.
  • Filter media such as multi-layered electret-containing filtration media for filtering gas streams (e.g., air) are described herein.
  • the filter media may be designed to have desirable properties such as stable filtration efficiency, high oil repellency, low resistance, and/or stable service life.
  • the filter media may be a composite of two or more types of fiber layers where each layer may be optimized to enhance its function without substantially negatively impacting the performance of another layer of the media. For example, one layer of the media may be designed to have a relatively high oil repellency, and another layer of the media may be designed to have stable filtration efficiency throughout the filter's lifetime.
  • One or more layers of the media may have a certain value of thickness over instantaneous resistance (and/or a ratio of thickness over instantaneous resistance between two layers), as described in more detail below.
  • the filter media described herein may be particularly well-suited for applications that involve filtering gas streams (e.g., face masks, cabin air filtration, vacuum filtration, room filtration, respirator equipment, as well as residential heating ventilation and air conditioning (HVAC) and industrial HVAC systems), though the media may also be used in other applications.
  • filtering gas streams e.g., face masks, cabin air filtration, vacuum filtration, room filtration, respirator equipment, as well as residential heating ventilation and air conditioning (HVAC) and industrial HVAC systems
  • one or more layers of the media may have a certain value of basis weight over air permeability (and/or a ratio of a value of basis weight over air permeability between two layers), as described in more detail below.
  • the filter media may optionally comprise a support layer with a relatively high air permeability (e.g., greater than or equal to 1100 CFM).
  • the filter may have a relatively low initial resistance and/or may have a particular final El efficiency according to the
  • the filter media may be needled together and in such embodiments does not comprise an adhesive or an adhesive layer, or is substantially free of adhesive.
  • the filter media described herein may include a first layer, optionally including a fluorinated species, and a second layer that is charged.
  • the first layer may be positioned upstream of the second layer (e.g., in a filter element) with respect to the direction of gas/fluid flow.
  • the first layer may remove at least a portion of an oil present in a gas stream being filtered such that reduced amounts of the oil penetrates into the second layer, thereby minimizing discharge of the second layer. Since the presence of charges in the second layer can improve the efficiency (e.g., initial efficiency) of the media, this configuration of layers can stabilize the filtration efficiency of the filter media throughout its lifetime.
  • the filter media described herein may advantageously have lower resistance leading to, for example, more breathability (e.g., for face mask applications) compared to certain existing filter media.
  • the second layer may be positioned upstream of the first layer (e.g., in a filter element) with respect to the direction of gas/fluid flow.
  • a filter media 100 may include a first layer 110 and a second layer 120 adjacent first layer 110.
  • first layer 110 may be directly adjacent (i.e., in direct contact with at least a portion of) second layer 120.
  • second layer 120 may be positioned upstream or downstream of, but not in contact with, first layer 110.
  • the first layer is a non-wet laid layer imparting, for example, good oleophobic properties (e.g., high oil repellency) to the filter media and the second layer may be a charged layer having, for example, high efficiency (e.g., initial efficiency) with a relatively open fibrous structure.
  • good oleophobic properties e.g., high oil repellency
  • the second layer may be a charged layer having, for example, high efficiency (e.g., initial efficiency) with a relatively open fibrous structure.
  • the filter media includes one or more support layers (e.g., spunbond layers), as described in more detail below.
  • first layer and second layer generally refer to different layers of a filter media and do not necessarily denote a particular order of the layers (e.g., within a filter element).
  • a first layer may be positioned upstream of the second layer with respect to the direction of fluid flow, in other embodiments the first layer may be positioned downstream of the second layer with respect to the direction of fluid flow.
  • first layer when a layer is referred to as being "adjacent" another layer, it can be directly adjacent to the layer, or one or more intervening layers also may be present.
  • a layer that is "directly adjacent" another layer means that no intervening layer is present.
  • each of the first layer and/or the second layer may include a single layer. In other embodiments, however, the first layer and/or the second layer may include more than one layer (i.e., sublayers) to form a multi-layered structure. Each sublayer within a layer may be formed by the same process as the other sublayers within the layer.
  • a first layer includes more than one sublayers formed by a non-wet laid process such as a meltblown process, a meltspun, a melt electro spinning, a solvent electrospinning, a centrifugal spinning process, or a spunbond process.
  • the plurality of sublayers may be the same or may differ based on certain features such as basis weight, efficiency (e.g., initial efficiency), and/or thickness.
  • each sublayer within a given layer comprises the same type of fibers as the other sublayer(s) within the given layer.
  • a first layer may include multiple sublayers, each sublayer including fibers formed by the same process (e.g., by a meltblown process).
  • the plurality of sublayers may be discrete and combined by any suitable method, such as lamination, point bonding, or collating.
  • the sublayers are substantially joined to one another (e.g., by lamination, point bonding, thermo-dot bonding, ultrasonic bonding, calendering, use of adhesives (e.g., glue-web), and/or co- pleating).
  • sublayers may be formed as a composite layer (e.g., by a non- wet laid process).
  • Each of the sublayers of the first layer and/or second layer may have any suitable basis weight and/or thickness, such as those basis weights and thicknesses described herein for the overall layer (e.g., the first layer, the second layer). Additionally, each of the sublayers of the first layer and/or second layer may have performance characteristics (e.g., resistance, efficiency) of those described herein for the overall layer.
  • a layer of the filter media may comprise two or more sublayers.
  • the first layer e.g., a non-wet laid layer
  • the first layer may comprise two or more non-wet laid sublayers.
  • filter media 102 shown in cross section, comprises a first layer 110 having a first non-wet laid sublayer 110a and a second non-wet laid sublayer 110b.
  • the filter media also includes a second layer 120 adjacent first layer 110.
  • the second layer e.g., an efficiency layer and/or a charged layer
  • filter media 104 comprises first layer 110 and second layer 120 adjacent first layer 110, and having a first sublayer 120a and a second sublayer 120b. While two sublayers in each layer are shown, those skilled in the would understand that more than two sublayers (e.g., three sublayers, four sublayers, five sublayers) are also possible.
  • a filter media 106 comprises first layer 110 having three non-wet laid sublayers 110a, 110b, and 110c, and second layer 120 adjacent first layer 110 having three charged sublayers 120a, 120b, and 120c. Other configurations are also possible.
  • the first layer comprises greater than or equal to 1, greater than or equal to 2, greater than or equal to 3, greater than or equal to 5, greater than or equal to 7, greater than or equal to 10, or greater than or equal to 12 sublayers (e.g., non-wet laid sublayers). In certain embodiments, the first layer comprises less than or equal to 15, less than or equal to 12, less than or equal to 10, less than or equal to 7, less than or equal to 5, less than or equal to 3, or less than or equal to 2 sublayers.
  • the second layer comprises greater than or equal to 1, greater than or equal to 2, greater than or equal to 3, greater than or equal to 5, greater than or equal to 7, greater than or equal to 10, or greater than or equal to 12 sublayers (e.g., charged sublayers). In certain embodiments, the second layer comprises less than or equal to 15, less than or equal to 12, less than or equal to 10, less than or equal to 7, less than or equal to 5, less than or equal to 3, or less than or equal to 2 sublayers.
  • the first layer is designed to have a particular value of basis weight over air permeability of the first layer.
  • the first layer may have a value of basis weight over air permeability of less than or equal to 0.2 g/m /CFM and greater than or equal to 0.000125 g/m /CFM or another suitable range described herein.
  • a value of basis weight over air permeability for a particular layer, as used herein, is the ratio of the basis weight of the layer (including all sublayers of the layer) to the air permeability of the layer (including all sublayers of the layer). Measurements of basis weight and air permeability are described in more detail below.
  • the first layer has a value of basis weight over air permeability of the first layer of less than or equal to 0.2 g/m /CFM, less than or equal to 0.1 g/m 2 /CFM, less than or equal to 0.05 g/m 2 /CFM, less than or equal to 0.01 g/m 2 /CFM, less than or equal to 0.005 g/m 2 /CFM, less than or equal to 0.001 g/m 2 /CFM, less than or equal to 0.0005 g/m 2 /CFM, or less than or equal to 0.00025 g/m 2 /CFM.
  • the first layer has a value of basis weight over air permeability of the first layer of greater than or equal to 0.000125 g/m /CFM, greater than or equal to 0.00025 g/m 2 /CFM, greater than or equal to 0.0005 g/m 2 /CFM, greater than or equal to 0.001 g/m 2 /CFM, greater than or equal to 0.005 g/m 2 /CFM, greater than or equal to 0.01
  • g/m /CFM greater than or equal to 0.05 g/m /CFM, or greater than or equal to 0.1 g/m /CFM. Combinations of the above-referenced ranges are also possible (e.g., less than or equal to 0.2 g/m 2 /CFM and greater than or equal to 0.000125 g/m 2 /CFM). Other ranges are also possible.
  • the first layer (including one or more sublayers of the first layer) may be designed to have a particular air permeability (e.g., such that the value of basis weight over air permeability of the first layer is greater than or equal to 0.000125 g/m 2 /CFM and less than or equal to 0.2 g/m 2 /CFM).
  • a particular air permeability e.g., such that the value of basis weight over air permeability of the first layer is greater than or equal to 0.000125 g/m 2 /CFM and less than or equal to 0.2 g/m 2 /CFM).
  • the air permeability of the first layer is greater than or equal to 100 CFM, greater than or equal to 200 CFM, greater than or equal to 250 CFM, greater than or equal to 300 CFM, greater than or equal to 350 CFM, greater than or equal to 400 CFM, greater than or equal to 450 CFM, greater than or equal to 500 CFM, greater than or equal to 550 CFM, greater than or equal to 600 CFM, greater than or equal to 650 CFM, greater than or equal to 700 CFM, or greater than or equal to 750 CFM.
  • the air permeability of the first layer is less than or equal to 800 CFM, less than or equal to 750 CFM, less than or equal to 700 CFM, less than or equal to 650 CFM, less than or equal to 600 CFM, less than or equal to 550 CFM, less than or equal to 500 CFM, less than or equal to 450 CFM, less than or equal to 400 CFM, less than or equal to 350 CFM, less than or equal to 300 CFM, less than or equal to 250 CFM, or less than or equal to 200 CFM. Combinations of the above referenced ranges are also possible (e.g., greater than or equal to 100 CFM and less than or equal to 800 CFM, greater than or equal to 200 CFM and less than or equal to 650 CFM). Other ranges are also possible. Air permeability, as used herein, is measured according to the test standard ASTM D737 over 38 cm surface area of the media and using a pressure of 125 Pa.
  • the first layer is designed to have a particular value of thickness over instantaneous resistance of the layer (i.e., a thickness over instantaneous resistance factor).
  • filter media comprising a first layer have a particular value of thickness over instantaneous resistance of the first layer (e.g., greater than or equal to 2 mils/mm H 2 0 and less than or equal to 50 mils/mm H 2 0, or another suitable range described herein) which can increase the performance of filter media (e.g., lower resistance) as compared to certain existing filter media that do not have this feature.
  • a value of thickness over instantaneous resistance is the ratio of the uncompressed thickness of a layer (including all sublayers of the layer) to the instantaneous resistance of the layer (including all sublayers of the layer). Measurements of uncompressed thickness and instantaneous resistance are described in more detail below.
  • the first layer has a value of thickness over instantaneous resistance of the first layer of greater than or equal to 2 mils/mm H 2 0, greater than or equal to 3 mils/mm H 2 0, greater than or equal to 5 mils/mm H 2 0, greater than or equal to 10 mils/mm H 2 0, greater than or equal to 15 mils/mm H 2 0, greater than or equal to 20 mils/mm H 2 0, greater than or equal to 25 mils/mm H 2 0, greater than or equal to 30 mils/mm H 2 0, greater than or equal to 35 mils/mm H 2 0, greater than or equal to 40 mils/mm H 2 0, or greater than or equal to 45 mils/mm H 2 0.
  • the first layer has a value of thickness over instantaneous resistance of the first layer of less than or equal to 50 mils/mm H 2 0, less than or equal to 45 mils/mm H 2 0, less than or equal to 40 mils/mm H 2 0, less than or equal to 35 mils/mm H 2 0, less than or equal to 30 mils/mm H 2 0, less than or equal to 25 mils/mm H 2 0, less than or equal to 20 mils/mm H 2 0, less than or equal to 15 mils/mm H 2 0, less than or equal to 10 mils/mm H 2 0, less than or equal to 5 mils/mm H 2 0, or less than or equal to 3 mils/mm H 2 0.
  • the first layer (including one or more sublayers of the first layer) may be designed to have a particular uncompressed thickness (e.g., such that the thickness over instantaneous resistance factor of the first layer is greater than or equal to 2 mils/mm H 2 0 and less than or equal to 50 mils/mm H 2 0).
  • the uncompressed thickness of the first layer may be greater than or equal to 1 mil, greater than or equal to 2 mils, greater than or equal to 5 mils, greater than or equal to 10 mils, greater than or equal to 25 mils, greater than or equal to 50 mils, greater than or equal to 100 mils, greater than or equal to 200 mils, greater than or equal to 250 mils, greater than or equal to 300 mils, or greater than or equal to 400 mils.
  • the uncompressed thickness of the first layer may be less than or equal to 500 mils, less than or equal to 400 mils, less than or equal to 300 mils, less than or equal to 250 mils, less than or equal to 200 mils, less than or equal to 100 mils, less than or equal to 50 mils, less than or equal to 25 mils, less than or equal to 10 mils, less than or equal to 5 mils, or less than or equal to 2 mils.
  • Uncompressed thickness is determined using a Mitutoya uncompressed thickness measurement. Briefly, the fiber layer is compressed using a circular probe having a diameter of 1 mm under at least three different weights (e.g., 10 grams, 5 grams, 2 grams). The ordinary least squares linear regression is determined for each weight and corresponding thickness, and is used to calculated the thickness of the fiber layer corresponding to 0 grams of applied weight to determine the uncompressed thickness for that layer.
  • the first layer may be designed to have a particular instantaneous resistance.
  • the first layer may have an instantaneous resistance of less than or equal to 40 mm H 2 0, less than or equal to 35 mm H 2 0, less than or equal to 30 mm H 2 0, less than or equal to 25 mm H 2 0, less than or equal to 20 mm H 2 0, less than or equal to 15 mm H 2 0, less than or equal to 10 mm H 2 0, less than or equal to 5 mm H 2 0, or less than or equal to 2 mm H 2 0.
  • the first layer may have an instantaneous resistance of greater than or equal to 0.1 mm H 2 0, greater than or equal to 0.2 mm H 2 0, greater than or equal to 0.5 mm H 2 0, greater than or equal to 1 mm H 2 0, greater than or equal to 2 mm H 2 0, greater than or equal to 5 mm H 2 0, greater than or equal to 10 mm H 2 0, greater than or equal to 15 mm H 2 0, greater than or equal to 20 mm H 2 0, greater than or equal to 25 mm H 2 0, greater than or equal to 30 mm H 2 0, or greater than or equal to 35 mm H 2 0.
  • the first layer (or each sublayer of the first layer) has a particular instantaneous penetration.
  • the instantaneous penetration of the first layer is less than or equal to 15%, less than or equal to 10%, less than or equal to 5%, less than or equal to 3%, less than or equal to 2%, less than or equal to 1%, or less than or equal to 0.5%.
  • the instantaneous penetration of the first layer is greater than or equal to 0.01%, greater than or equal to 0.1%, greater than or equal to 0.5%, greater than or equal to 1%, greater than or equal to 2%, greater than or equal to 3%, greater than or equal to 5%, or greater than or equal to 10%. Combinations of the above-referenced ranges are also possible (e.g., less than or equal to 15% and greater than or equal to 0.01%). Other ranges are also possible. Measurements of instantaneous penetration are described below.
  • the first layer (or each sublayer of the first layer) comprises a plurality of fibers.
  • the fibers of the first layer (or each sublayer of the first layer) may be continuous or non-continuous.
  • Continuous fibers and are made by a "continuous" fiber-forming process, such as a meltblown process, a meltspun, a melt electro spinning, a solvent electrospinning, a centrifugal spinning process, or a spunbond process, and typically have longer lengths than non-continuous fibers as described in more detail below.
  • Non-continuous fibers are staple fibers that are generally cut (e.g., from a filament) or formed as non-continuous discrete fibers to have a particular length or a range of lengths as described in more detail below.
  • the plurality of fibers of the first layer include synthetic fibers (synthetic polymer fibers).
  • the synthetic fibers of the first layer may be continuous fibers or staple fibers.
  • suitable synthetic fibers include polyester, polyaramid, polyimide, polyolefin (e.g., polyethylene), polypropylene, Kevlar, Nomex, halogenated polymers (e.g., polyethylene terephthalate), acrylics, polyphenylene oxide,
  • Synthetic fibers may also include multi-component fibers (i.e., fibers having multiple compositions such as bicomponent fibers).
  • the synthetic fibers of the first layer are meltblown fibers, meltspun fibers, melt electrospun fibers, solvent electrospun fibers, centrifugal spun fibers, spunbond fibers, and/or combinations thereof, which may be formed of polymers described herein (e.g., polyester, polypropylene).
  • Synthetic fibers of the first layer may also include staple fibers.
  • the staple fibers may be multi-component fibers (i.e., fibers having multiple compositions such as bicomponent fibers).
  • the layer may also include a binder (e.g., binder resin).
  • a binder e.g., binder resin
  • the plurality of fibers (e.g., synthetic fibers, continuous fibers, staple fibers) in the first layer (or in each sublayer of the first layer) may have an average diameter of greater than or equal to 0.2 microns, greater than or equal to 0.5 microns, greater than or equal to 1 micron, greater than or equal to 2 microns, greater than or equal to 3 microns, greater than or equal to 4 microns, greater than or equal to 5 microns, greater than or equal to 6 microns, greater than or equal to 8 microns, greater than or equal to 10 microns, greater than or equal to 15 microns, or greater than or equal to 20 microns.
  • the plurality of fibers in the first layer may have an average diameter of less than or equal to 20 microns, less than or equal to 15 microns, less than or equal to 10 microns, less than or equal to 8 microns, less than or equal to 7 microns, less than or equal to 6 microns, less than or equal to 5 microns, less than or equal to 4 microns, less than or equal to 3 microns, less than or equal to 2 microns, less than or equal to 1 micron, or less than or equal to 0.5 microns.
  • Combinations of the above-referenced ranges are also possible (e.g., greater than or equal to 0.2 micron and less than or equal to 20 microns, greater than or equal to 1 micron and less than or equal to about 10 microns, greater than or equal to 1 micron and less than or equal to 8 microns).
  • Other values of average fiber diameter for the first layer (or each sublayer of the first layer) are also possible.
  • the first layer comprises a plurality of fibers (e.g., synthetic fibers, continuous fibers) having a continuous length.
  • the plurality of fibers in the first layer may have an average length of greater than about 5 inches, greater than or equal to about 10 inches, greater than or equal to about 25 inches, greater than or equal to about 50 inches, greater than or equal to about 100 inches, greater than or equal to about 300 inches, greater than or equal to about 500 inches, greater than or equal to about 700 inches, or greater than or equal to about 900 inches.
  • the fibers may have an average length of less than or equal to about 1000 inches, less than or equal to about 800 inches, less than or equal to about 600 inches, less than or equal to about 400 inches, or less than or equal to about 100 inches. Combinations of the above-referenced ranges are also possible (e.g., greater than or equal to about 50 inches and less than or equal to about 1000 inches). Other ranges are also possible.
  • the first layer comprises a plurality of fibers (e.g., synthetic fibers, staple fibers) having an average length of less than about 5 inches (127 mm).
  • the plurality of fibers in the first layer may have an average length of, for example, less than or equal to about 100 mm, less than or equal to about 80 mm, less than or equal to about 60 mm, less than or equal to about 40 mm, less than or equal to about 20 mm, less than or equal to about 10 mm, less than or equal to about 5 mm, less than or equal to about 1 mm, less than or equal to about 0.5 mm, or less than or equal to about 0.1 mm.
  • plurality of fibers in the first layer may have an average length of greater than or equal to about 0.02 mm, greater than or equal to about 0.1 mm, greater than or equal to about 0.5 mm, greater than or equal to about 1 mm, greater than or equal to about 5 mm, greater than or equal to about 10 mm, greater than or equal to about 20 mm, greater than or equal to about 40 mm, greater than or equal to about 60 mm. Combinations of the above-referenced ranges are possible (e.g., greater than or equal to about 0.02 mm and less than or equal to about 80 mm, greater than or equal to about 0.03 mm and less than or equal to about 40 mm). Other ranges are also possible.
  • the first layer may have certain structural characteristics, such as basis weight and/or solidity.
  • the first layer (or each of the sub-layers of the first layer) may have a basis weight of greater than or equal to 0.1 g/m 2 , greater than or equal to 0.5 g/m 2 , greater than or equal to 1 g/m 2 , greater than or equal to 3 g/m 2 , greater than or equal to 10 g/m 2 , greater than or equal to
  • the first layer (or each of the sub-layers of the first layer) may have a basis weight of less than or equal to
  • 500 g/m 2 less than or equal to 400 g/m 2 , less than or equal to 300 g/m 2 , less than or equal to 200 g/m 2 , less than or equal to 100 g/m 2 , less than or equal to 90 g/m 2 , less than or equal to 85 g/m 2 , less than or equal to 80 g/m 2 , less than or equal to 70 g/m 2 , less than or equal to 60 g/m 2 , less than or equal to 50 g/m 2 , less than or equal to 40 g/m 2 , less than or equal to 30 g/m 2 , less than or equal to 25 g/m 2 , less than or equal to 10 g/m 2 , less than or equal to 3 g/m 2 , less than or equal to 1 g/m 2 , or less than or equal to 0.5 g/m 2.
  • a basis weight of greater than or equal to 0.1 g/m 2 and less than or equal to 500 g/m 2 e.g., a basis weight of greater than or equal to 10 g/m 2 and less than or equal to 250 g/m 2 , a basis weight of greater than or equal to 6 g/m 2 and less than or equal to 80 g/m 2 , a basis weight of greater than or equal to 0.1 g/m 2 and less than or equal to 20 g/m 2 ).
  • Other values of basis weight are also possible.
  • the basis weight may be determined according to the standard ISO 536.
  • the first layer has a basis weight of less than or equal to 20 g/m .
  • the first layer (or each of the sub-layers of the first layer) may have a solidity of greater than or equal to 0.1%, greater than or equal to 0.5%, greater than or equal to 1%, greater than or equal to 5%, greater than or equal to 10%, greater than or equal to 20%, or greater than or equal to 40%.
  • the first layer (or each of the sub-layers of the first layer) may have a solidity of less than or equal to 50%, less than or equal to 40%, less than or equal to 30%, less than or equal to 20%, less than or equal to 10%, less than or equal to 5%, less than or equal tol%, or less than or equal to 0.5%. Combinations of the above-referenced ranges are also possible (e.g., a solidity of greater than or equal to 0.1% and less than or equal to 50%, greater than or equal to 1% and less than or equal to 20%). Other ranges are also possible. Solidity generally refers to the percentage of volume of solids with respect to the total volume of the layer.
  • the first layer (or one or more sublayers of the first layer) comprises a fluorinated species.
  • each sublayer of the first layer comprises a fluorinated species.
  • the fluorinated species may impart a certain level of oil repellency to the media.
  • Non-limiting examples of fluorinated species include fluorocarbons such as those having the formula -C n F 2n+ i or -C n F m , where n is an integer greater than 1, and m is an integer greater than 1. In some embodiments, n is less than or equal to 8, less than or equal 6, less than or equal 5, or less than or equal to 4.
  • m is less than or equal to 14, less than or equal to 13, less than or equal to 12, less than or equal to 8, less than or equal 6, less than or equal 5, or less than or equal to 4.
  • fluorocarbons include CF 4 , C 2 F 4 , C 3 F 6 , C 3 F 8 , C 4 F 8 , C 5 F 12 , C 6 F 6 , C 6 Fi 2 , and C 6 Fi 3 .
  • fluorinated species include fluorocarbons such as those having the formula C n F m -(C x H y )-Z, where n is an integer equal or greater than 1, m is an integer equal or greater than 1, x is an integer greater than 0, y is an integer greater than 0, and Z is an end functional group that can be selected from the group consisting of acrylate, methacrylate, alcohol, aldehyde, carboxylic acid, olefins, silane, bromide, iodide, thiol, amine, phenol, isocyanate, sulfonate, epoxide, and ether.
  • fluorocarbons such as those having the formula C n F m -(C x H y )-Z, where n is an integer equal or greater than 1, m is an integer equal or greater than 1, x is an integer greater than 0, y is an integer greater than 0, and Z is an end functional group that can be selected from the group consisting of
  • n is less than or equal to 11, less than or equal to 8, less than or equal 6, less than or equal 5, or less than or equal to 4.
  • m is less than or equal to 14, less than or equal to 13, less than or equal to 12, less than or equal to 8, less than or equal 6, less than or equal 5, or less than or equal to 4.
  • x is less than or equal to 12, less than or equal to 8, less than or equal 6, less than or equal 5, or less than or equal to 4.
  • y is less than or equal to 25, less than or equal to 20, less than or equal to 15, less than or equal to 10, less than or equal to 8, less than or equal 6, less than or equal 5, or less than or equal to 4.
  • the value of m may vary depending on the value of n, and the value of y may depend on the value of x.
  • -(C x H y )- is a linear alkane or a branched alkane.
  • one or more fluorinated species are present in the first layer (e.g., as a coating) in an amount of greater than or equal to 0.01%, greater than or equal to 0.05%, greater than or equal to 0.1%, greater than or equal to 0.5%, greater than or equal to 0.75%, greater than or equal to 1%, greater than or equal to 2%, greater than or equal to 3%, or greater than or equal to 5% by weight of the total dry weight of the first layer.
  • one or more fluorinated species are present in the first layer (e.g., as a coating) in an amount of less than or equal to 10%, less than or equal to 5%, less than or equal to 3%, less than or equal to 2%, less than or equal to 1%, less than or equal to 0.75%, less than or equal to 0.5%, less than or equal to 0.1%, or less than or equal to 0.05% by weight of the total dry weight of the first layer.
  • Combinations of the above referenced ranges are also possible (e.g., greater than or equal to 0.01% and less than or equal to 10%, greater than or equal to 0.01% and less than or equal to 5%, greater than or equal to 0.05% and less than or equal to 3%, greater than or equal to 0.1% and less than or equal to 2%, greater than or equal to 0.2% and less than or equal to 0.75%).
  • Other ranges are also possible.
  • the first layer, or one or more sublayers of the first layer may be modified to comprise a fluorinated species using any suitable method.
  • the entire layer may be modified (e.g., through its thickness).
  • the interior and the surfaces of the layer (or one or more sublayers of the layer) may be modified with a fluorinated species.
  • the interior of the layer (or one or more sublayers of the layer) may be modified without one or more outer surfaces of the layer (or one or more sublayers of the layer) being modified.
  • any suitable method for modifying the surface and/or the interior of a layer (or one or more sublayers of the layer) may be used.
  • a coating method is used to coat a layer with a fluorinated species.
  • filter media may undergo a coating process (e.g., chemical vapor deposition), such that one or more outer surfaces of an interior layer and/or bottom layer is not coated, while the porous interior of the layer is coated.
  • the surface and/or interior of a layer (or one or more sublayers of the layer) may be modified by coating at least a portion of the surface and/or interior.
  • a coating process involves introducing resin or a material (e.g., a fluorinated species) dispersed in a solvent or solvent mixture into a pre-formed fiber layer (e.g., a pre-formed fiber layer formed by a meltblown process, etc.).
  • a material e.g., a fluorinated species
  • a pre-formed fiber layer e.g., a pre-formed fiber layer formed by a meltblown process, etc.
  • Non-limiting examples of coating methods include the use of vapor deposition (e.g., chemical vapor, physical vapor deposition), layer-by-layer deposition, wax- solidification, self-assembly, sol-gel processing, a slot die coater, gravure coating, screen coating, size press coating (e.g., a two roll-type or a metering blade type size press coater), film press coating, blade coating, roll-blade coating, air knife coating, roll coating, foam application, reverse roll coating, bar coating, curtain coating, champlex coating, brush coating, Bill-blade coating, short dwell-blade coating, lip coating, gate roll coating, gate roll size press coating, laboratory size press coating, melt coating, dip coating, knife roll coating, spin coating, spray coating (e.g., electro spraying), gapped roll coating, roll transfer coating, padding saturant coating, and saturation impregnation.
  • vapor deposition e.g., chemical vapor, physical vapor deposition
  • layer-by-layer deposition e.g
  • the first layer described herein may be modified using chemical vapor deposition (e.g., chemical vapor deposition of a fluorinated species).
  • chemical vapor deposition the fiber layer is exposed to gaseous reactants from gas or liquid vapor that are deposited onto the fiber layer under high energy level excitation such as thermal, microwave, UV, electron beam or plasma.
  • a carrier gas such as oxygen, helium, argon and/or nitrogen may be used.
  • vapor deposition methods include atmospheric pressure chemical vapor deposition (APCVD), low pressure chemical vapor deposition (LPCVD), metal-organic chemical vapor deposition (MOCVD), plasma assisted chemical vapor deposition (PACVD) or plasma enhanced chemical vapor deposition (PECVD), laser chemical vapor deposition (LCVD), photochemical vapor deposition (PCVD), chemical vapor infiltration (CVI) and chemical beam epitaxy (CBE).
  • APCVD atmospheric pressure chemical vapor deposition
  • LPCVD low pressure chemical vapor deposition
  • MOCVD metal-organic chemical vapor deposition
  • PCVD plasma assisted chemical vapor deposition
  • PECVD plasma enhanced chemical vapor deposition
  • LCVD laser chemical vapor deposition
  • PCVD photochemical vapor deposition
  • CVI chemical vapor infiltration
  • CBE chemical beam epitaxy
  • PVD physical vapor deposition
  • This method involves physical processes such as high-temperature vacuum evaporation with subsequent condensation, or plasma sputter bombardment rather than a chemical reaction.
  • the coating may be dried or cured by any suitable method.
  • drying or curing methods include the use of a photo dryer, infrared dryer, ultraviolet source, electron beam, hot air oven steam- heated cylinder, or any suitable type of dryer familiar to those of ordinary skill in the art.
  • the first layer (and any sublayers), the second layer, and/or the entire media does not include a fluorinated species (e.g., does not comprise a coating such as a chemical vapor deposition coating comprising a fluorinated species).
  • the first layer, or one or more sublayers of the first layer may be, in some cases, charged.
  • the first layer comprises a plurality of charged fibers.
  • the first layer (or one or more sublayers of the first layer) is/are not charged.
  • a filter media may include a second layer with optional sublayers.
  • the second layer is an efficiency layer (i.e., it increases the efficiency/initial efficiency of the overall media).
  • the second layer is a charged layer (an electret layer).
  • the second layer is designed to have a particular value of basis weight over air permeability of the second layer.
  • filter media comprising a second layer have a particular value of basis weight over air permeability of the second layer (e.g., greater than or equal to 0.03 g/m /CFM and less than or equal to 0.25 g/m /CFM, or another suitable range described herein).
  • a value of basis weight over air permeability is the ratio of the basis weight (including all sublayers of the layer) to the air permeability (including all sublayers of the layer). Measurements of basis weight and air permeability are described herein.
  • the second layer has a value of basis weight over air permeability of the second layer of less than or equal to 0.25 g/m /CFM, less than or
  • 0.2 g/m /CFM less than or equal to 0.175 g/m /CFM, less than or equal to 0.15 g/m 2 /CFM, less than or equal to 0.125 g/m 2 /CFM, less than or equal to 0.1 g/m 2 /CFM,
  • the second layer has a value of basis weight over air permeability of the second layer of greater than or equal to 0.03 g/m /CFM, greater than or equal to 0.04
  • g/m /CFM greater than or equal to 0.05 g/m /CFM, greater than or equal to 0.07 g/m 2 /CFM, greater than or equal to 0.09 g/m 2 /CFM, greater than or equal to 0.1 g/m 2 /CFM, greater than or equal to 0.125 g/m 2 /CFM, greater than or equal to 0.15 g/m 2 /CFM, greater than or equal to 0.175 g/m 2 /CFM, or greater than or equal to 0.2 g/m /CFM. Combinations of the above-referenced ranges are also possible (e.g., greater than or equal to 0.03 g/m 2 /CFM and less than or equal to 0.25 g/m 2 /CFM). Other ranges are also possible.
  • the second layer (including one or more sublayers of the second layer) may be designed to have a particular air permeability (e.g., such that the value of basis weight over air permeability of the second layer is greater than or equal to 0.03 g/m 2 /CFM and less than or equal to 0.25 g/m 2 /CFM).
  • a particular air permeability e.g., such that the value of basis weight over air permeability of the second layer is greater than or equal to 0.03 g/m 2 /CFM and less than or equal to 0.25 g/m 2 /CFM).
  • the air permeability of the second layer is greater than or equal to 200 CFM, greater than or equal to 250 CFM, greater than or equal to 300 CFM, greater than or equal to 330 CFM, greater than or equal to 350 CFM, greater than or equal to 400 CFM, greater than or equal to 500 CFM, greater than or equal to 600 CFM, greater than or equal to 650 CFM, greater than or equal to 700 CFM, greater than or equal to 800 CFM, or greater than or equal to 900 CFM.
  • the air permeability of the second layer is less than or equal to 1000 CFM, less than or equal to 900 CFM, less than or equal to 800 CFM, less than or equal to 700 CFM, less than or equal to 600 CFM, less than or equal to 500 CFM, less than or equal to 400 CFM, less than or equal to 350 CFM, less than or equal to 330 CFM, less than or equal to 300 CFM, or less than or equal to 250 CFM.
  • the second layer is designed to have a particular thickness over instantaneous resistance factor.
  • filter media comprising a second layer have a particular value of thickness over instantaneous resistance of the second layer (e.g., greater than or equal to 20 mils/mm H 2 0 and less than or equal to 150 mils/mm H 2 0, or another suitable range as described herein), which can increase the performance of filter media (e.g., lower resistance) as compared to certain existing filter media that do not have this feature.
  • the second layer has a value of thickness over instantaneous resistance of the second layer (i.e., a thickness over instantaneous resistance factor) of greater than or equal to 20 mils/mm H 2 0, greater than or equal to 30 mils/mm H 2 0, greater than or equal to 40 mils/mm H 2 0, greater than or equal to 50 mils/mm H 2 0 mils/mm H 2 0, greater than or equal to 75 mils/mm H 2 0, greater than or equal to 100 mils/mm H 2 0, or greater than or equal to 125 mils/mm H 2 0.
  • a thickness over instantaneous resistance factor of greater than or equal to 20 mils/mm H 2 0, greater than or equal to 30 mils/mm H 2 0, greater than or equal to 40 mils/mm H 2 0, greater than or equal to 50 mils/mm H 2 0 mils/mm H 2 0, greater than or equal to 75 mils/mm H 2 0, greater than or equal to 100 mils/mm H 2 0, or greater than or equal to 125 mils/mm H 2 0.
  • the second layer has a thickness over instantaneous resistance factor of less than or equal to 150 mils/mm H 2 0, less than or equal to 125 mils/mm H 2 0, less than or equal to 100 mils/mm H 2 0, less than or equal to 75 mils/mm H 2 0, less than or equal to 50 mils/mm H 2 0, less than or equal to 40 mils/mm H 2 0, or less than or equal to 30 mils/mm H 2 0.
  • Combinations of the above-referenced ranges are also possible (e.g., greater than or equal to 20 mils/mm H 2 0 and less than or equal to 150 mils/mm H 2 0, greater than or equal to 40 mils/mm H 2 0 and less than or equal to 125 mils/mm H 2 0).
  • Other ranges are also possible.
  • the second layer may be designed to have a particular uncompressed thickness (e.g., such that the thickness over instantaneous resistance factor of the second layer is greater than or equal to 20 mils/mm H 2 0 and less than or equal to 150 mils/mm H 2 0).
  • the uncompressed thickness of the second layer may be greater than or equal to 5 mils, greater than or equal to 10 mils, greater than or equal to 25 mils, greater than or equal to 30 mils, greater than or equal to 50 mils, greater than or equal to 100 mils, greater than or equal to 200 mils, greater than or equal to 250 mils, greater than or equal to 300 mils, greater than or equal to 350 mils, greater than or equal to 400 mils, or greater than or equal to 500 mils.
  • the uncompressed thickness of the second layer may be less than or equal to 600 mils, less than or equal to 500 mils, less than or equal to 400 mils, less than or equal to 350 mils, less than or equal to 300 mils, less than or equal to 250 mils, less than or equal to 200 mils, less than or equal to 100 mils, less than or equal to 50 mils, less than or equal to 30 mils, less than or equal to 25 mils, or less than or equal to 10 mils. Combinations of the above referenced ranges are also possible (e.g., greater than or equal to 5 mils and less than or equal to 600 mils, greater than or equal to 30 mils and less than or equal to 350 mils). Other ranges are also possible.
  • the second layer may be designed to have a particular
  • the second layer may have an instantaneous resistance of greater than or equal to 0.1 mm H 2 0, greater than or equal to 0.2 mm H 2 0, greater than or equal to 0.5 mm H 2 0, greater than or equal to 1 mm H 2 0, greater than or equal to 2 mm H 2 0, or greater than or equal to 5 mm H 2 0. In some embodiments, the second layer may have an instantaneous resistance of less than or equal to 10 mm H 2 0, less than or equal to 5 mm H 2 0, or less than or equal to 2 mm H 2 0.
  • the second layer (or each sublayer of the second layer) as a particular instantaneous penetration.
  • the instantaneous penetration of the second layer is less than or equal to 50%, less than or equal to 45%, less than or equal to 40%, less than or equal to 35%, less than or equal to 30%, less than or equal to 25%, less than or equal to 20%, less than or equal to 15%, less than or equal to 10%, less than or equal to 5%, less than or equal to 3%, less than or equal to 2%, less than or equal to 1%, or less than or equal to 0.5%.
  • the instantaneous penetration of the second layer is less than or equal to 50%, less than or equal to 45%, less than or equal to 40%, less than or equal to 35%, less than or equal to 30%, less than or equal to 25%, less than or equal to 20%, less than or equal to 15%, less than or equal to 10%, less than or equal to 5%, less than or equal to 3%, less than or equal to 2%, less than or equal to 1%, or less
  • instantaneous penetration of the second layer is greater than or equal to 0.01%, greater than or equal to 0.1%, greater than or equal to 0.5%, greater than or equal to 1%, greater than or equal to 2%, greater than or equal to 3%, greater than or equal to 5%, greater than or equal to 10%, greater than or equal to 20%, greater than or equal to 30%, or greater than or equal to 40%. Combinations of the above-referenced ranges are also possible (e.g., less than or equal to 15% and greater than or equal to 0.01%, less than or equal to 50% and greater than or equal to 0.01%). Other ranges are also possible. Measurements of instantaneous penetration are described below.
  • the second layer (or each sublayer of the second layer) comprises a plurality of fibers.
  • the fibers of the second layer (or each sublayer of the second layer) may be non-continuous (e.g., staple fibers) or continuous, and may be optionally charged. Accordingly, the second layer may be charged in some
  • the plurality of fibers of the second layer include synthetic fibers (synthetic polymer fibers).
  • the synthetic fibers of the second layer may be staple fibers or continuous fibers.
  • Non-limiting examples of suitable synthetic fibers include polypropylene, dry-spun acrylic (e.g., produced from a dry-spinning process), polyvinyl chloride, mod-acrylic, wet spun acrylic, polytetrafluoroethylene, polypropylene, polystyrene, polysulfone, polyethersulfone, polycarbonate, nylon (e.g., nylon 6/6), polyurethane, phenolic, polyvinylidene fluoride, polyester, polyaramid, polyimide, polyolefin (e.g., polyethylene), Kevlar, Nomex, halogenated polymers (e.g., polyethylene terephthalate), polyacrylics, polyphenylene oxide, polyphenylene sulfide, and
  • the synthetic fibers are halogen-free such that significant dioxins are not detectable when incinerated.
  • the fibers may be halogen-free acrylic fibers formed by dry spinning.
  • the second layer and/or the entire filter media is halogen-free such that significant dioxins are not detectable when incinerated.
  • the plurality of fibers in the second layer are staple fibers that are synthetic polymer fibers, and are carded.
  • the fibers of the second layer may be charged.
  • the plurality of fibers in the second layer include synthetic fibers (synthetic polymer fibers) formed by a continuous fiber-forming process such as a meltblown process, a meltspun, a melt electrospinning, a solvent electrospinning, a centrifugal spinning process, or a spunbond process.
  • synthetic fibers synthetic polymer fibers
  • a continuous fiber-forming process such as a meltblown process, a meltspun, a melt electrospinning, a solvent electrospinning, a centrifugal spinning process, or a spunbond process.
  • the synthetic fibers are meltblown fibers, meltspun fibers, melt electrospun fibers, solvent electrospun fibers, centrifugal spun fibers, spunbond fibers, and/or combinations thereof.
  • Synthetic fibers may also include multi-component fibers (i.e., fibers having multiple compositions such as bicomponent fibers).
  • synthetic fibers may include meltblown fibers, which may be formed of polymers described herein (e.g., polyester, polypropylene). Other processes and materials used to form the second layer are also possible. The fibers of the second layer may be charged.
  • the second layer comprises a mixture of two or more polymeric fibers.
  • the second layer may comprise at least a first plurality of fibers comprising a first polymer and a second plurality of fibers comprising a second polymer.
  • the first polymer and the second polymer are selected such that the first polymer and the second polymer have different dielectric constants.
  • the two polymers having different dielectric constants may facilitate charging of the layer (e.g., triboelectric charging).
  • two polymers with different dielectric constants in the layer may come into frictional contact during manufacture of the layer such that one polymer will lose electrons and give them away to the other polymer and, as a result, the polymer losing electrons is net positively charged, the other polymer receiving electrons is net negatively charged.
  • the charged layer may have one or more characteristics described in commonly-owned U.S. Patent No.
  • the second layer is an electrostatically charged layer formed by blending together polypropylene fibers with halogen free acrylic fibers, polypropylene with polyvinyl chloride (PVC) fibers, or a mixture of halogen free acrylic fibers and PVC fibers and, optionally, carding the blended fibers so as to form a non- woven fabric.
  • PVC polyvinyl chloride
  • the difference in dielectric constants between the first polymer and the second polymer may be selected to be greater than or equal to 0.8, greater than or equal to 1, greater than or equal to 1.2, greater than or equal to 1.5, greater than or equal to 2, greater than or equal to 3, greater than or equal to 5, or greater than or equal to 7.
  • the difference in dielectric constants between the first polymer and the second polymer may be selected to be less than or equal to 8, less than or equal to 7, less than or equal to 5, less than or equal to 3, less than or equal to 2, less than or equal to 1.5, less than or equal to 1.2, or less than or equal to 1.
  • Combinations of the above-referenced ranges are also possible (e.g., greater than or equal to 0.8 and less than or equal to 8, greater than or equal to 1.5 and less than or equal to 5). Other ranges are also possible.
  • Table 1 shows dielectric constants for several exemplary polymers.
  • the first polymer and the second polymer may be present in the second layer (or in each of the sublayers of the second layer) in any suitable amount.
  • the first polymer is present in the second layer (or in each of the sublayers of the second layer) in an amount of greater than or equal to 25 wt%, greater than or equal to 30 wt%, greater than or equal to 35 wt%, greater than or equal to 40 wt%, greater than or equal to 50 wt%, greater than or equal to 60 wt%, greater than or equal to 65 wt%, or greater than or equal to 70 wt% with respect to the total amount of fibers in the layer and/or the total weight of the layer.
  • the first polymer is present in the second layer in an amount of less than or equal to 75 wt%, less than or equal to 70 wt%, less than or equal to 65 wt%, less than or equal to 60 wt%, less than or equal to 50 wt%, less than or equal to 40 wt%, less than or equal to 35 wt%, or less than or equal to 30 wt% with respect to the total amount of fibers in the layer and/or the total weight of the layer. Combinations of the above referenced ranges are also possible (e.g., greater than or equal to 25 wt% and less than or equal to 75 wt%). Other ranges are also possible.
  • the second polymer is present in the second layer (or in each of the sublayers of the second layer) in an amount of less than or equal to 75 wt%, less than or equal to 70 wt%, less than or equal to 65 wt%, less than or equal to 60 wt%, less than or equal to 50 wt%, less than or equal to 40 wt%, less than or equal to 35 wt%, or less than or equal to 30 wt% with respect to the total amount of fibers in the layer and/or the total weight of the layer.
  • the second polymer is present in the second layer in an amount of greater than or equal to 25 wt%, greater than or equal to 30 wt%, greater than or equal to 35 wt%, greater than or equal to 40 wt%, greater than or equal to 50 wt%, greater than or equal to 60 wt%, greater than or equal to 65 wt%, or greater than or equal to 70 wt% with respect to the total amount of fibers in the layer and/or the total weight of the layer. Combinations of the above referenced ranges are also possible (e.g., greater than or equal to 25 wt% and less than or equal to 75 wt%). Other ranges are also possible.
  • the second layer comprises the first polymer in an amount of greater than or equal to about 25 wt% and less than or equal to 75 wt% and the second polymer in an amount of less than or equal to 75 wt% and greater than or equal to about 25 wt% with respect to the total amount of fibers in the layer.
  • the second layer may comprise the first polymer in an amount of greater than or equal to about 45 wt% and less than or equal to 55 wt%, and the second polymer in an amount of less than or equal to 55 wt% and greater than or equal to about 45 wt%, with respect to the total amount of fibers in the layer.
  • the second layer comprises each of the first polymer and the second polymer in an amount of about 50 wt% with respect to the total amount of fibers in the layer.
  • the second layer comprises a plurality of fibers (e.g., synthetic fibers, staple fibers) having an average length of less than about 5 inches (127 mm).
  • the plurality of fibers in the second layer may have an average length of, for example, less than or equal to about 100 mm, less than or equal to about 80 mm, less than or equal to about 60 mm, less than or equal to about 40 mm, less than or equal to about 20 mm, less than or equal to about 10 mm, less than or equal to about 5 mm, less than or equal to about 1 mm, less than or equal to about 0.5 mm, or less than or equal to about 0.1 mm.
  • plurality of fibers in the second layer may have an average length of greater than or equal to about 0.02 mm, greater than or equal to about 0.1 mm, greater than or equal to about 0.5 mm, greater than or equal to about 1 mm, greater than or equal to about 5 mm, greater than or equal to about 10 mm, greater than or equal to about 20 mm, greater than or equal to about 40 mm, greater than or equal to about 60 mm. Combinations of the above-referenced ranges are possible (e.g., greater than or equal to about 1 mm and less than or equal to about 80 mm, greater than or equal to about 1 mm and less than or equal to about 60 mm). Other ranges are also possible.
  • the second layer comprises a plurality of fibers (e.g., synthetic fibers, continuous fibers) having a continuous length.
  • the plurality of fibers in the second layer may have an average length of greater than about 5 inches, greater than or equal to about 10 inches, greater than or equal to about 25 inches, greater than or equal to about 50 inches, greater than or equal to about 100 inches, greater than or equal to about 300 inches, greater than or equal to about 500 inches, greater than or equal to about 700 inches, or greater than or equal to about 900 inches.
  • the fibers may have an average length of less than or equal to about 1000 inches, less than or equal to about 800 inches, less than or equal to about 600 inches, less than or equal to about 400 inches, or less than or equal to about 100 inches. Combinations of the above-referenced ranges are also possible (e.g., greater than or equal to about 50 inches and less than or equal to about 1000 inches).
  • the second layer may have certain structural characteristics, such as basis weight and/or solidity.
  • the second layer (or each of the sub-layers of the second layer) may have a basis weight of greater than or equal to 20 g/m 2 , greater than or equal to 25 g/m 2 , greater than or equal to 30 g/m 2 , greater than or equal to 40 g/m 2 , greater than or equal to 50 g/m 2 , greater than or equal to 60 g/m 2 , greater than or equal to 70 g/m 2 , greater than or equal to 80 g/m 2 , greater than or equal to 85 g/m 2 , greater than or equal to 90 g/m 2 , greater than or equal to 100 g/m 2 , greater than or equal to 200 g/m 2 , greater than or equal to 300 g/m 2 , greater than or equal to 400 g/m 2 , or greater than or equal to 500 g/m 2.
  • the second layer (or each of the sub-layers of the second layer) may have a basis weight of less than or equal to 600 g/m 2 , less than or equal to 500 g/m 2 , less than or equal to 400 g/m 2 , less than or equal to 300 g/m 2 , less than or equal to 200 g/m 2 , less than or equal to 100 g/m 2 , less than or equal to 90 g/m 2 , less than or equal to 85 g/m 2 , less than or equal to 80 g/m 2 , less than or equal to 70 g/m 2 , less than or equal to 60 g/m 2 , less than or equal to 50 g/m 2 , less than or equal to 40 g/m 2 , or less than or equal to 30 g/m 2.
  • the basis weight may be determined as described above.
  • the second layer has a basis weight of greater than or equal to 30 g/m and less than or equal to 85 g/m .
  • the second layer (or each of the sub-layers of the second layer) may have a solidity of greater than or equal to 0.1%, greater than or equal to 0.5%, greater than or equal to 1.0%, greater than or equal to 5.0%, greater than or equal to 10%, greater than or equal to 20%, or greater than or equal to 40%. In certain embodiments, the second layer (or each of the sub-layers of the second layer) may have a solidity of less than or equal to 50%, less than or equal to 40%, less than or equal to 20%, less than or equal to 10%, less than or equal to 5%, less than or equal tol%, or less than or equal to 0.5%. Combinations of the above-referenced ranges are also possible (e.g., a solidity of greater than or equal to 0.1% and less than or equal to 50%, greater than or equal to 1% and less than or equal to 20%). Other ranges are also possible.
  • the filter media may be a multi- layered electret-containing media.
  • a layer e.g., a second layer
  • the net charge of the layer may be negative or positive.
  • at least a surface of the second layer may comprise a negatively charged material and/or a positively charged material.
  • the polymers in the second layer may be selected based on their dielectric constant and/or position on the triboelectric series, as described herein.
  • the second layer is formed via a carding process (e.g., where the fibers are manipulated by rollers and extensions (e.g., hooks, needles)).
  • the polymer fibers within the second layer with a significant difference in dielectric constant and/or that are relatively far apart on the triboelectric series may undergo contact electrification as a result of the carding process to produce a charged non- woven web.
  • Charged non- woven webs may have enhanced performance properties, including an increased efficiency, compared to a similar non-woven web that is uncharged, all other factors being equal.
  • a layer may be neutral (e.g., have no net charge).
  • the filter media described herein may have a relatively low pressure drop (i.e., resistance) and/or a relatively long lifetime as compared to certain existing filter media.
  • the filter media may have a decrease in resistance (e.g., initial resistance) when the media includes at least two layers, wherein the ratio of the value of thickness over instantaneous resistance of the second layer to the value of thickness over instantaneous resistance of the first layer (i.e., a TRF ratio) is less than or equal 20.
  • the media passes a P95 filter media test as described in more detail below.
  • the filter media described herein may have a relatively low pressure drop (i.e., resistance) as compared to certain existing filter media when the media includes at least two layers and the ratio of the value of basis weight over air permeability of the first layer to the value of the basis weight over air permeability of the second layer less than or equal to 5 (e.g., less than or equal to 4).
  • the filter media may have a ratio of the value of basis weight over air permeability of the first layer to the value of basis weight over air permeability of the second layer (WO A ratio) of less than or equal to 5, less than or equal to 4, less than or equal to 3, less than or equal to 2, less than or equal to 1, less than or equal to 0.5, less than or equal to 0.25, less than or equal to 0.2, less than or equal to 0.1, less than or equal to 0.05, or less than or equal to 0.02.
  • the filter media may have a ratio of the value of basis weight over air permeability of the first layer to the value of basis weight over air permeability of the second layer of greater than or equal to 0.01, greater than or equal to 0.02, greater than or equal to 0.05, greater than or equal to 0.1, greater than or equal to 0.2, greater than or equal to 0.25, greater than or equal to 0.5, greater than or equal to 1, greater than or equal to 2, greater than or equal to 3, or greater than or equal to 4. Combinations of the above referenced ranges are also possible (e.g., greater than or equal to 0.01 and less than or equal to 5, greater than or equal to 0.02 and less than or equal to 3). Other ranges are also possible.
  • the filter media may have a particular composite air permeability.
  • Composite air permeability refers to the total air permeability of a filter media comprising at least a first layer and a second layer, and is measured according to the ASTM D737 test described herein.
  • the composite air permeability of the filter media is greater than or equal to 200 CFM, greater than or equal to 250 CFM, greater than or equal to 300 CFM, greater than or equal to 350 CFM, greater than or equal to 400 CFM, greater than or equal to 450 CFM, greater than or equal to 500 CFM, or greater than or equal to 550 CFM.
  • the composite air permeability of the filter media is less than or equal to 600 CFM, less than or equal to 550 CFM, less than or equal to 500 CFM, less than or equal to 450 CFM, less than or equal to 400 CFM, less than or equal to 350 CFM, less than or equal to 300 CFM, or less than or equal to 250 CFM. Combinations of the above referenced ranges are also possible (e.g., greater than or equal to 200 CFM and less than or equal to 600 CFM). Other ranges are also possible.
  • a filter media described herein may have a particular final El efficiency (e.g., a final El efficiency of greater than or equal to 36%), according to the ASHRAE 52.2 standard.
  • the final El efficiency of the filter media is greater than or equal to 36%, greater than or equal to 40%, greater than or equal to 50%, greater than or equal to 60%, greater than or equal to 70%, greater than or equal to 80%, greater than or equal to 90%, greater than or equal to 95%, greater than or equal to 98%, greater than or equal to 99%, greater than or equal to 99.5%, greater than or equal to 99.8%, greater than or equal to 99.9%, or greater than or equal to 99.99%.
  • the final El efficiency of the filter media is less than or equal to 100%, less than or equal to 99.99%, less than or equal to 99.9%, less than or equal to 99.8%, less than or equal to 99.5%, less than or equal to 99%, less than or equal to 98%, less than or equal to 95%, less than or equal to 90%, less than or equal to 80%, less than or equal to 70%, less than or equal to 60%, less than or equal to 50%, or less than or equal to 40%. Combinations of the above-referenced ranges are also possible (e.g., a final El efficiency of greater than or equal to 36% and less than or equal to 100%, greater than or equal to 36% and less than or equal to 90%). Other ranges are also possible.
  • the ASHRAE 52.2 test used herein involves a test air flow rate of 295 feet per minute (FPM) where the final pressure drop when the efficiency is measured is 1.5 inches of H 2 0 on a column.
  • the test is run at an air temperature of 20°C, a relative humidity of 40%, and a barometric pressure of 29.30 in Hg.
  • Test conditions needs to be modified slightly as below.
  • the testing uses a challenge aerosol of atomized KC1 particles having a range of particle sizes between 0.3-1.0 microns (for determining El final efficiency), 1.0-3.0 microns (for determining E2 final efficiency), and/or 3.0-10.0 microns (for determining E3 final efficiency).
  • the final El efficiency is determined by calculating the average minimum particle size efficiency for four ranges of particle sizes within the 0.3-1.0 micron particle size range: 0.3-0.4 micron particle size, 0.4-0.55 micron particle size, 0.55-0.7 micron particle size, 0.7-1.0 micron particle size, i.e., according to the following equation:
  • minPSE@(x-y micron particle size) is the minimum particle size efficiency for particles having a given x-y micron particle size range (e.g., 0.3-0.4 micron particle size particles).
  • Particle size efficiency is determined by the following equation:
  • a filter media described herein may have a particular final E2 efficiency (e.g., a final E2 efficiency of greater than or equal to 80%), according to the ASHRAE 52.2 standard.
  • the final E2 efficiency of the filter media is greater than or equal to 80%, greater than or equal to 90%, greater than or equal to 95%, greater than or equal to 98%, greater than or equal to 99%, greater than or equal to 99.5%, or greater than or equal to 99.8%.
  • the final E2 efficiency of the filter media is less than or equal to 99.9%, less than or equal to 99.8%, less than or equal to 99.5%, less than or equal to 99%, less than or equal to 98%, less than or equal to 95%, or less than or equal to 90%. Combinations of the above- referenced ranges are also possible (e.g., a final E2 efficiency of greater than or equal to 80% and less than or equal to 100%, greater than or equal to 80% and less than or equal to 90%). Other ranges are also possible.
  • the final E2 efficiency is determined by calculating the average minimum particle size removal efficiency for four ranges of particle sizes within the 1.0-3.0 micron particle size range: 1.0-1.3 micron particle size, 1.3-1.6 micron particle size, 1.6-2.2 micron particle size, 2.2-3.0 micron particle size, i.e., according to the following equation:
  • minPSE@(x-y micron particle size) is the minimum particle size efficiency for particles having a given x-y micron particle size range (e.g., 1.0-3.0 micron particle size particles).
  • a filter media described herein may have a particular final E3 efficiency (e.g., a final E3 efficiency of greater than or equal to 90%), according to the ASHRAE 52.2 standard.
  • the final E3 efficiency of the filter media is greater than or equal to 90%, greater than or equal to 95%, greater than or equal to 98%, greater than or equal to 99%, greater than or equal to 99.5%, or greater than or equal to 99.8%.
  • the final E3 efficiency of the filter media is less than or equal to 99.9%, less than or equal to 99.8%, less than or equal to 99.5%, less than or equal to 99%, less than or equal to 98%, or less than or equal to 95%. Combinations of the above-referenced ranges are also possible (e.g., a final E3 efficiency of greater than or equal to 90% and less than or equal to 100%). Other ranges are also possible.
  • the final E3 efficiency is determined by calculating the average minimum particle size removal efficiency for four ranges of particle sizes within the 3.0-10.0 micron particle size range: 3.0-4.0 micron particle size, 4.0-5.5 micron particle size, 5.5- 7.0 micron particle size, 7.0-10.0 micron particle size, i.e., according to the following equation:
  • minPSE@(x-y micron particle size) is the minimum particle size efficiency for particles having a given x-y micron particle size range (e.g., 3.0-10.0 micron particle size particles).
  • the filter media may have a ratio of the value of thickness over instantaneous resistance of the second layer to the value of thickness over instantaneous resistance of the first layer of less than or equal to 20, less than or equal to 15, less than or equal to 10, less than or equal to 5, less than or equal to 3, less than or equal to 2, or less than or equal to 1.
  • the filter media may have a ratio of the value of thickness over instantaneous resistance of the second layer to the value of thickness over instantaneous resistance of the first layer of greater than or equal to 0.5, greater than or equal to 1, greater than or equal to 2, greater than or equal to 3, greater than or equal to 5, greater than or equal to 10, or greater than or equal to 15.
  • the value of the thickness over instantaneous resistance of the second layer is greater than the value of the thickness over instantaneous resistance of the first layer (e.g., such that the ratio of the value of thickness over instantaneous resistance of the second layer to the value of thickness over instantaneous resistance of the first layer is greater than 1).
  • Combinations of the above-referenced ranges are also possible (e.g., greater than or equal to 0.5 and less than or equal to 20, greater than or equal to 1 and less than or equal to 10). Other ranges are also possible.
  • a filter media described herein passes a P95 filter media test performed according to the NIOSH P-95 standard (NIOSH TEB-APR-STP-0053 (Revision 2.0)). Briefly, for a filter media to pass a P95 test, the maximum penetration during 200 mg loading of DOP should not exceed 5%, and the bandwidth of the filter media, defined as the penetration difference at 26 minutes and 30 minutes of the penetration test, should not exceed 0.1%. Maximum penetration and bandwidth are described in more detail below.
  • the filter media having a TRF ratio within one or more ranges described above may pass a P95 test.
  • the filter media having a TRF ratio within one or more ranges described above may pass a P99 test or a P100 test as described herein.
  • a filter media described herein passes a P99 filter media test performed according to the
  • NIOSH P-99 standard (NIOSH TEB-APR-STP-0052 (Revision 2.0)). Briefly, for a filter media to pass a P99 test, the maximum penetration during 200 mg loading of DOP should not exceed 1% and the bandwidth of the filter media, defined as the penetration difference at 26 minutes and 30 minutes of the penetration test, should not exceed 0.023%.
  • the filter media comprising a first layer and a second layer passes a P100 filter media test performed according to the NIOSH P-100 standard (NIOSH TEB-APR-STP-0051 (Revision 2.0)). Briefly, for a filter media to pass a P100 test, the maximum penetration during 200 mg loading of DOP should not exceed 0.03% and the bandwidth of the filter media, defined as the penetration difference at 26 minutes and 30 minutes, should not exceed 0.004%.
  • a filter media may have a ratio of the value of thickness over instantaneous resistance of the second layer to the value of thickness over instantaneous resistance of the first layer of less than or equal to 50, less than or equal to 40, less than or equal to 30, less than or equal to 20, less than or equal to 15, less than or equal to 10, less than or equal to 5, less than or equal to 3, less than or equal to 2, or less than or equal to 1.
  • the filter media may have a ratio of the value of thickness over instantaneous resistance of the second layer to the value of thickness over instantaneous resistance of the first layer of greater than or equal to 0.5, greater than or equal to 1, greater than or equal to 2, greater than or equal to 3, greater than or equal to 5, greater than or equal to 10, greater than or equal to 15, greater than or equal to 20, greater than or equal to 30, or greater than or equal to 40. Combinations of the above- referenced ranges are also possible (e.g., greater than or equal to 0.5 and less than or equal to 50, greater than or equal to 1 and less than or equal to 30). Other ranges are also possible.
  • a filter media comprises a first layer comprising a plurality of fibers and a second layer adjacent the first layer.
  • the first layer comprises a fluorinated species.
  • the first layer has a first value of a thickness over instantaneous resistance of the first layer
  • the second layer has a second value of a thickness over instantaneous resistance of the second layer
  • the ratio of the second value to the first value is less than or equal to 20.
  • the filter media has an initial efficiency of greater than or equal to 95%.
  • a filter media comprises a first layer (e.g., a meltblown layer) comprising a plurality of meltblown fibers and a fluorinated species (e.g., a fluorinated species having the formula -C n F2 n+1 , -C n F m , or C n F m -(C x H y )-Z, where n is an integer equal or greater than 1 and less than or equal to 11, m is an integer equal or greater than 1 and less than or equal to 14, x is an integer greater than 0 and less than or equal to 12, y is an integer greater than 0 and less than or equal to 25, and Z is an end functional group that can be selected from the group consisting of acrylate, methacrylate, alcohol, aldehyde, carboxylic acid, olefins, silane, bromide, iodide, thiol, amine, phenol, isocyanate, sulfonate, a fluorinated
  • the fluorinated species may be deposited onto/into the first layer by a CVD deposition process or another suitable process.
  • the filter media also includes a second layer directly adjacent the first layer.
  • the second layer comprises a first plurality of fibers (e.g., synthetic fibers such as dry spun acrylic fibers) and a second plurality fibers (e.g., synthetic fibers such as polypropylene fibers).
  • the second layer is a charged layer.
  • Other materials for the first and/or second plurality of fibers may also be used (e.g., two fibers that have a certain difference in dielectric constant as described herein).
  • the first polymer and the second polymer have a difference in dielectric constants of at least about 0.8.
  • a filter media comprises a first layer comprising at least three meltblown sublayers, each sublayer comprising a plurality of meltblown fibers and a fluorinated species (e.g., a fluorinated species having the formula -C n F2n + i, -C n F m , or C n F m -(C x H y )-Z, where n is an integer equal or greater than 1 and less than or equal to 11, m is an integer equal or greater than 1 and less than or equal to 14, x is an integer greater than 0 and less than or equal to 12, y is an integer greater than 0 and less than or equal to 25, and Z is an end functional group that can be selected from the group consisting of acrylate, methacrylate, alcohol, aldehyde, carboxylic acid, olefins, silane, bromide, iodide, thiol, amine, phenol, isocyanate, sulfonate
  • the filter media also includes a second layer directly adjacent the first layer, the second layer comprising at least two sublayers.
  • Each sublayer may comprise a first plurality of fibers (e.g., synthetic fibers such as dry spun acrylic fibers) and a second plurality of fibers (e.g., synthetic fibers such as polypropylene fibers).
  • Other materials for the first and/or second plurality of fibers may also be used (e.g., two fibers that have a certain difference in dielectric constant as described herein).
  • the first polymer and the second polymer have a difference in dielectric constants of at least about 0.8.
  • the second layer may be charged.
  • a filter media comprises a first layer comprises at least two meltblown sublayers, each sublayer comprising a plurality of meltblown fibers and a fluorinated species (e.g., a fluorinated species having the formula -C n F2n+i, -C n F m , or C n F m -(C x H y )-Z, where n is an integer equal or greater than 1 and less than or equal to 11, m is an integer equal or greater than 1 and less than or equal to 14, x is an integer greater than 0 and less than or equal to 12, y is an integer greater than 0 and less than or equal to 25, and Z is an end functional group that can be selected from the group consisting of acrylate, methacrylate, alcohol, aldehyde, carboxylic acid, olefins, silane, bromide, iodide, thiol, amine, phenol, isocyanate, sulfonate,
  • the second layer may comprise a first plurality of fibers
  • first polymer and the second polymer have a difference in dielectric constants of at least about 0.8.
  • the second layer may be charged.
  • the filter media further comprises one or more support layers (e.g., a meltblown layer, a spunbond layer, a wet-laid layer, a dry-laid layer).
  • filter media 100 comprises a first layer 110, a second layer 120 , and a support layer 130 (e.g., a third layer).
  • the first layer may be adjacent the second layer, although other configurations are also possible.
  • the support layer e.g., the third layer
  • the support layer may be adjacent the second layer or disposed between the first layer and the second layer.
  • the support layer may be attached to the first layer to provide support for the first layer, and/or may be attached to the second layer to provide support for the second layer.
  • a support layer is positioned between the first layer and the second layer.
  • the second layer e.g., a charged layer
  • the support layer e.g., a third layer
  • the second layer e.g., a charged layer
  • the support layer e.g., a third layer
  • the second layer (e.g., a charged layer) is upstream of the first layer (e.g., a non-wet laid layer) and the support layer (e.g., a third layer) is adjacent to and upstream of the second layer.
  • the second layer e.g., a charged layer
  • the first layer e.g., a non-wet laid layer
  • the support layer e.g., a third layer
  • the second layer e.g., a charged layer
  • the first layer e.g., a third layer
  • the support layer e.g., a third layer
  • Such a support layer is a separate layer and is not included in the calculation of the value of thickness over instantaneous resistance for the first layer or the second layer, nor included into the calculation of the values of basis weight over air permeability for the first layer or the second layer.
  • the support layer(s) may be formed of a different fiber type (including a different fiber composition/materials) than fibers of the first layer and/or fibers of second layer.
  • the one or more support layers comprise a plurality of spunbond fibers, wetlaid fibers, drylaid fibers and/or meltblown fibers.
  • the support layer e.g., spunbond layer
  • the support layer may be coated (e.g., with a fluorinated species) as described herein.
  • the support layer e.g., spunbond layer
  • the support layer may be needled to the second layer.
  • the support layer aids in fabrication and/or manipulation of the layer(s), but is removed from the first and/or second layer prior to incorporation of the layer(s) into a filter media and/or a filter element.
  • the support layer(s) may be present in the final filter media and/or a filter element.
  • the support layer comprises a plurality of fibers comprising a polymer.
  • suitable polymers for the support layer include polypropylene, high density polyethylene, low density polyethylene, linear low density polyethylene, ethylene- vinyl acetate, polyamide, polyurethane, polyethylene terephthalate, polylactic acid, and copolymers thereof.
  • a single fiber composition is used to form the support layer.
  • the support layer may be designed to have a particular air permeability.
  • the air permeability of the support layer is greater than or equal to 1100 CFM, greater than or equal to 1500 CFM, greater than or equal to 2000 CFM, greater than or equal to 3000 CFM, greater than or equal to 4000 CFM, greater than or equal to 5000 CFM, greater than or equal to 6000 CFM, greater than or equal to 7000 CFM, greater than or equal to 8000 CFM, or greater than or equal to 9000 CFM.
  • the air permeability of the support layer is less than or equal to 10000 CFM, less than or equal to 9000 CFM, less than or equal to 8000 CFM, less than or equal to 7000 CFM, less than or equal to 6000 CFM, less than or equal to 5000 CFM, less than or equal to 4000 CFM, less than or equal to 3000 CFM, less than or equal to 2000, or less than or equal to 1500 CFM. Combinations of the above referenced ranges are also possible (e.g., greater than or equal to 1100 CFM and less than or equal to 10000 CFM). Other ranges are also possible.
  • the support layer may have a particular basis weight.
  • the basis weight of the support layer may be greater than or equal to 0.5 g/m 2 , greater than or equal to 1 g/m 2 , greater than or equal to 2 g/m 2 , greater than or equal to 5 g/m 2 , greater than or equal to
  • the basis weight of the support layer is less than or equal to 150 g/m 2 , less than or equal to 100 g/m 2 , less than or equal to 50 g/m 2 , less than or equal to 20 g/m 2 , less than or equal to 10 g/m 2 , less than or equal to 5 g/m 2 , less than or equal to 2 g/m 2 , or less than or equal to 1 g/m 2.
  • a filter media comprises a first layer comprising a plurality of fibers and a second layer adjacent the first layer.
  • the first layer and the second layer may be mated to one another using various techniques in the art.
  • the first layer and the second layer may be mated by needling.
  • the filter media further comprises a support layer (e.g., a third layer)
  • the first layer, second layer, and support layer may be mated to one another by needling.
  • the filter media does not comprise an adhesive and/or an adhesive layer, or is substantially free of adhesive.
  • the filter media may have a particular needle density
  • the needle density of the filter media is between 10 PPSI and 30 PPSI.
  • the needle density of the filter media is greater than or equal to 10 PPSI, greater than or equal to 12 PPSI, greater than or equal to 15 PPSI, greater than or equal to 17 PPSI, greater than or equal to 20 PPSI, or greater than or equal to 25 PPSI.
  • the needle density of the filter media is less than or equal to 30 PPSI, less than or equal to 25 PPSI, less than or equal to 20 PPSI, less than or equal to 17 PPSI, less than or equal to 15 PPSI, or less than or equal to 12 PPSI. Combinations of the above referenced ranges are also possible (e.g., greater than or equal to 10 PPSI and less than or equal to 30 PPSI). Other ranges are also possible.
  • a filter media comprises a first layer comprising a plurality of fibers and a second layer adjacent the first layer.
  • the first layer has a first value of a thickness over instantaneous resistance of the first layer
  • the second layer has a second value of a thickness over instantaneous resistance of the second layer
  • the ratio of the second value to the first value is less than or equal to 20.
  • the filter media has an initial efficiency of greater than or equal to 95%.
  • a filter media comprises a first layer comprising a plurality of fibers and a second layer.
  • the first layer is adjacent the second layer.
  • the second layer is charged.
  • the first layer has a first value of a basis weight over air permeability of the first layer
  • the second layer has a second value of a basis weight over air permeability of the second layer
  • the ratio of the first value to the second value is less than or equal to 5 (e.g., less than or equal to 4).
  • the filter media has an final El efficiency of greater than or equal to 36%.
  • such a media has a first layer having a basis weight of less than or equal to 20 g/m and a plurality of fibers having an average fiber diameter of greater than or equal to 1 micron and less than or equal to 8 microns.
  • the second layer has a basis weight of greater than or equal to 30 g/m and less than or equal to 85 g/m 2 .
  • the filter media having the WOA ratio of less than or equal to 5 (e.g., less than or equal to 4) has an initial resistance of less than or equal to 1.6 mm H 2 0 (or another suitable range described herein).
  • the first layer may have air permeability of greater than or equal to 200 CFM and less than or equal to 650 CFM.
  • the first layer may comprise two or more sublayers and/or may be a non-wet laid layer.
  • the first layer comprises a plurality of meltblown fibers, meltspun fibers, melt electrospun fibers, solvent electrospun fibers, centrifugal spun fibers, spunbond fibers, and/or combinations thereof.
  • the second layer has an air permeability of greater than or equal to 330 CFM and less than or equal to 1000 CFM.
  • the second layer may comprise two or more sublayers and/or may comprise a first plurality of fibers comprising a first polymer and a second plurality of fibers comprising a second polymer (wherein the first and second polymers are different).
  • the first polymer may comprise acrylic (e.g., dry spun acrylic) and the second polymer may comprise polypropylene.
  • the second layer may be positioned upstream relative to the first layer or in any other suitable configuration described herein.
  • the filter media comprises a support layer having an air permeability of greater than or equal to 1100 CFM and less than or equal to 10000 CFM.
  • the filter media may be needled and/or does not comprise an adhesive or adhesive layer, or is substantially free of adhesive.
  • the filter media may have a final El efficiency of greater than or equal to 36%, according to the ASHRAE 52.2 standard described herein.
  • a filter element comprises a filter media described herein.
  • Such filter elements may be used, for example, in an HVAC filter.
  • the first layer does not include a fluorinated species and is not charged.
  • the first layer may include a fluorinated species as described herein.
  • the first layer has a value of basis weight over air permeability of the first layer of greater than or equal to 0.000125 g/m 2 CFM and less than or equal to 0.2 g/m 2 CFM (or another suitable range described herein), and the second layer has a value of basis weight over air permeability of the second layer of greater than or equal to 0.03 g/m CFM and less than or equal to 0.25 g/m CFM (or another suitable range described herein).
  • the first layer has a first value of a basis weight over air permeability of the first layer and the second layer has a second value of a basis weight over air permeability of the second layer, such that the ratio of the first value to the second value is less than or equal to 5 (or another suitable range described herein, e.g., less than or equal to 4).
  • the first layer has a value of thickness over instantaneous resistance of the first layer of greater than or equal to 2 mils/mmH 2 0 and less than or equal to 50 mils/mm H 2 0 (or another suitable range described herein), and the second layer has a value of thickness over instantaneous resistance of the second layer of greater than or equal to 20 mils/mmH 2 0 and less than or equal to 150 mils/mm H 2 0 (or another suitable range described herein).
  • the first layer has a first value of a thickness over instantaneous resistance of the first layer and the second layer has a second value of a thickness over instantaneous resistance of the second layer, such that the ratio of the second value to the first value is less than or equal to 20 (or another suitable range described herein).
  • the basis weight of the first layer is greater than or equal to 0.1 g/m and less than or
  • the basis weight of the second layer is greater than or equal to 20 g/m and less than or equal to 600 g/m 2 (e.g., greater than or equal to 50 g/m 2 and less than or equal to 200 g/m 2 ).
  • the basis weight of the first layer is less than or equal to 20 g/m and/or the basis weight of the second layer is greater than or equal to 30 g/m 2 and less than or equal to 85 g/m 2.
  • the first plurality of fibers comprises a first polymer and the second plurality of fibers comprises a second polymer where the first polymer and the second polymer have a difference in dielectric constants of at least about 0.8.
  • the filter media may be designed to have a particular ratio of the solidity of the first layer to the solidity of the second layer.
  • the ratio of the solidity of the first layer to the solidity of the second layer is greater than or equal to 0.1, greater than or equal to 0.5, greater than or equal to 1, greater than or equal to 2, greater than or equal to 5, greater than or equal to 10, or greater than or equal to 20.
  • the ratio of the solidity of the first layer to the solidity of the second layer may be less than or equal to 25, less than or equal to 20, less than or equal to 10, less than or equal to 5, less than or equal to 2, less than or equal to 1, or less than or equal to 0.5. Combinations of the above-referenced ranges are also possible (e.g., greater than or equal to 0.1 and less than or equal to 25, greater than or equal to 1 and less than or equal to 5). Other ranges are also possible.
  • the total thickness of the filter media may be greater than or equal to 30 mils, greater than or equal to 40 mils, greater than or equal to 50 mils, greater than or equal to 75 mils, greater than or equal to 100 mils, greater than or equal to 150 mils, greater than or equal to 200 mils, greater than or equal to 250 mils, greater than or equal to 300 mils, greater than or equal to 500 mils, or greater than or equal to 750 mils.
  • the total thickness of the filter media is less than or equal to 1000 mils, less than or equal to 750 mils, less than or equal to 500 mils, less than or equal to 300 mils, less than or equal to 250 mils, less than or equal to 200 mils, less than or equal to 150 mils, less than or equal to 100 mils, less than or equal to 75 mils, less than or equal to 50 mils, or less than or equal to 40 mils. Combinations of the above-referenced ranges are also possible (e.g., greater than or equal to 30 mils and less than or equal to 1000 mils, greater than or equal to 30 mils and less than or equal to 300 mils, greater than or equal to 50 mils and less than or equal to 200 mils).
  • Total thickness is measured using a Federal C&R thickness gauge according to the standard ASTM D1778. Briefly, the gauge has 1 square inch area in contact with the filter media and uses a 2 ounce load to lightly compress the sample as follows: the gauge is zeroed first without the filter media, then raised to allow enough space to insert the filter media, then lowered again to rest on the filter media without impact. The total thickness is noted on the dial.
  • a filter media and/or a layer may be designed to have a particular resistance (e.g., instantaneous resistance, initial resistance), penetration (e.g., instantaneous penetration, initial penetration, maximum penetration, bandwidth) or efficiency (e.g., instantaneous efficiency, initial efficiency). Resistance, penetration and efficiency are measured using a 8130
  • DOP DiOctyl Phthalate
  • the particle size created by the DOP particle generator is 0.3 microns (mass mean diameter).
  • the test involves using a DOP particle concentration in an air stream of about 125 mg/m , for a continuous 30 minute challenge to accumulate 200 mg loading at a face velocity 16.4 FPM over a 100 cm face area of the filter media/layer.
  • Initial resistance, initial penetration, and initial efficiency are determined at 1 minute after starting the test.
  • Maximum penetration corresponds to the maximum penetration measurement during the 30 minute test.
  • Bandwidth is calculated by taking the percentage difference in penetration between measurements obtained at 26 minutes and 30 minutes of the test.
  • the filter media comprising a first layer and a second layer as described herein may have lower initial resistance compared to certain existing filter media.
  • the initial resistance of a filter media described herein is less than or equal to 35 mm H 2 0, less than or equal to 30 mm H 2 0, less than or equal to 25 mm H 2 0, less than or equal to 20 mm H 2 0, less than or equal to 15 mm H 2 0, less than or equal to 10 mm H 2 0, less than or equal to 9, less than or equal to 8 mm H 2 0, less than or equal to 5 mm H 2 0, less than or equal to 4 mm H 2 0, less than or equal to 3 mmH 2 0, less than or equal to 2 mm H 2 0, less than or equal to 1.6 mm H 2 0, less than or equal to 1 mm H 2 0, less than or equal to 0.5 mm H 2 0, less than or equal to 0.1 mm H 2 0, or less than or equal to 0.05 mm H O.
  • the initial resistance of the filter media is greater than or equal to 0.01 mm H 2 0, greater than or equal to 0.05 mm H 2 0 , greater than or equal to 0.1 mm H 2 0, greater than or equal to 0.5 mm H 2 0 , greater than or equal to 1 mm H 2 0, greater than or equal to 1.6 mm H 2 0, greater than or equal to 2 mm H 2 0, greater than or equal to 4 mm H 2 0, greater than or equal to 5 mm H 2 0, greater than or equal to 10 mm H 2 0, greater than or equal to 15 mm H 2 0, greater than or equal to 20 mm H 2 0, greater than or equal to 25 mm H 2 0, or greater than or equal to 30 mm H 2 0.
  • the filter media (e.g., a filter media that passes a P95 test as described herein) comprising a first layer and a second layer as described herein has an initial resistance of less than 1.6 mm H 2 0.
  • the filter media and/or layer may have a particular efficiency and/or penetration.
  • efficiency is determined as 100-% Penetration. Penetration, expressed as a percentage, is defined as
  • Pen (C/Co)* 100, where C is the particle concentration after passage through the filter media and Co is the particle concentration before passage through the filter media.
  • the instantaneous efficiency of the filter media is greater than or equal to 90%, greater than or equal to 92%, greater than or equal to 95%, greater than or equal to 96%, greater than or equal to 97%, greater than or equal to 98%, greater than or equal to 99%, greater than or equal to 99.5%, greater than or equal to 99.8%, greater than or equal to 99.9%, or greater than or equal to 99.99%.
  • the instantaneous efficiency of the filter media is less than or equal to 100%, less than or equal to 99.99%, less than or equal to 99.9%, less than or equal to 99.8%, less than or equal to 99.5%, less than or equal to 99%, less than or equal to 98%, less than or equal to 97%, less than or equal to 96%, less than or equal to 95%, or less than or equal to 92%. Combinations of the above-referenced ranges are also possible (e.g., an instantaneous efficiency of greater than or equal to 90% and less than or equal to 100%, greater than or equal to 95% and less than or equal to 100%). Other ranges are also possible.
  • the initial efficiency of the filter media is greater than or equal to 90%, greater than or equal to 92%, greater than or equal to 95%, greater than or equal to 96%, greater than or equal to 97%, greater than or equal to 98%, greater than or equal to 99%, greater than or equal to 99.5%, greater than or equal to 99.8%, greater than or equal to 99.9%, or greater than or equal to 99.99%.
  • the initial efficiency of the filter media is less than or equal to 100%, less than or equal to 99.99%, less than or equal to 99.9%, less than or equal to 99.8%, less than or equal to 99.5%, less than or equal to 99%, less than or equal to 98%, less than or equal to 97%, less than or equal to 96%, less than or equal to 95%, or less than or equal to 92%. Combinations of the above-referenced ranges are also possible (e.g., an initial efficiency of greater than or equal to 90% and less than or equal to 100%, greater than or equal to 95% and less than or equal to 100%). Other ranges are also possible.
  • the filter media described herein may be designed to have a particular range of maximum penetration.
  • the filter media described herein has a maximum penetration of less than or equal to 10%, less than or equal to 5%, less than or equal to 2%, less than or equal to 1%, less than or equal to 0.5%, or less than or equal to 0.1%.
  • the filter media has a maximum penetration of greater than or equal to 0%, greater than or equal to 0.1%, greater than or equal to 0.5%, greater than or equal to 1%, greater than or equal to 2%, or greater than or equal to 5%.
  • Combinations of the above-referenced ranges are also possible (e.g., greater than or equal to 0% and less than or equal to 10%, greater than or equal to 0% and less than or equal to 2%).
  • the filter media described herein may have a bandwidth.
  • the bandwidth gives an indication of stability of a filter media's efficiency during extended usage, wherein lower values of bandwidth indicate greater stability of the filter media's efficiency compared to higher values.
  • the bandwidth of the filter media is less than or equal to 3%, less than or equal to 2%, less than or equal to 1%, less than or equal to 0.5%, less than or equal to 0.1%, less than or equal to 0.05%, less than or equal to 0.023%, less than or equal to 0.005%, or less than or equal to 0.004%.
  • the bandwidth of the filter media is greater than or equal to 0%, greater than or equal to 0.004%, greater than or equal to 0.005%, greater than or equal to 0.023%, greater than or equal to 0.05%, greater than or equal to 0.1%, greater than or equal to 0.5%, greater than or equal to 1%, or greater than or equal to 2%. Combinations of the above-referenced ranges are also possible (e.g., less than or equal to 3% and greater than or equal to 0%, less than or equal to 0.1% and greater than or equal to 0.1%). Other ranges are also possible.
  • the filter media described herein may be tailored to have a particular oil repellency level.
  • Such filter media may be used, for example, to remove or coalesce oil, lubricants, and/or cooling agents from a gas stream that passes through the filter media.
  • the oil repellency level of the filter media or layer or sublayer is between 1 and 7 (e.g., 1-4, 2-5, 3-6, 4-7). In certain embodiments, the oil repellency level of the filter media or layer or sublayer is 1, 2, 3, 4, 5, 6, or 7.
  • Oil repellency level as described herein is determined according to AATCC TM 118 (1997) measured at 23 °C and 50% relative humidity (RH). Briefly, 5 drops of each test oil (having an average droplet diameter of about 2 mm) are placed on five different locations on the surface of the filter media or layer or sublayer. The test oil with the greatest oil surface tension that does not wet (e.g., has a contact angle greater than or equal to 90 degrees with the surface) the surface of the filter media or layer or sublayer after 30 seconds of contact with the filter media at 23 °C and 50% RH, corresponds to the oil repellency level (listed in Table 2).
  • the filter media or layer or sublayer has an oil repellency level of
  • the filter media or layer or sublayer has an oil repellency level of
  • the filter media or layer or sublayer has an oil repellency level of 6.
  • the oil repellency level is expressed to the nearest 0.5 value determined by subtracting 0.5 from the number of the test liquid.
  • the filter media or layer or sublayer has an oil repellency level of 5.5.
  • Oil Repellency Level Test Oil Surface tension (in mN/m)
  • a layer of the filter media may be a non-wet laid layer formed using a non-wet laid process (e.g., an air laid process, a carding process, a meltblown process).
  • a non-wet laid process e.g., an air laid process, a carding process, a meltblown process.
  • an air laid process or a carding process may be used.
  • fibers may be mixed while air is blown onto a conveyor.
  • the fibers are manipulated by rollers and extensions (e.g., hooks, needles) associated with the rollers.
  • a layer of the filter media may include fibers formed from a meltblown process.
  • the meltblown layer may have one or more characteristics described in commonly-owned U.S. Patent No. 8,608,817, entitled “Meltblown Filter Medium", issued on December 17, 2013, which is based on U.S. Patent Application Serial No. 12/266,892 filed on May 14,
  • 2012/0152824 entitled “Fine Fiber Milter Media and Processes”, which is based on Patent Application No. 12/971,539 filed on December 17, 2010, and commonly-owned U.S. Patent Publication No. 2012/0152821, entitled “Fine Fiber Milter Media and Processes", which is based on Patent Application No. 12/971,594 filed on December 17,
  • the filter media may be used for a number of applications, such as respirator and face mask applications, cabin air filtration, military garments, HVAC systems (e.g., for industrial areas and buildings), clean rooms, vacuum filtration, room air cleaning, and respirator protection equipment (e.g., industrial respirators).
  • the filter media may be incorporated into a face mask.
  • the filter media can be, for example, folded, edge sealed, collated, or molded, with or without a supporting structure, within the face mask.
  • the face mask may be a full face piece or a half face piece, and may be disposable or reusable. In general, face masks are used to protect the respiratory system when the air contains hazardous amounts of particulate contaminants in the form of solid particles or liquid droplets that can cause impairment through inhalation.
  • a face mask generally needs to provide adequate protection with good breathability (e.g., low resistance).
  • the face mask may be designed to filter dust, fog, fumes, vapors, smoke, sprays or mists.
  • face masks may be worn in areas where activities such as grinding, welding, road paving (e.g., where hot asphalt fumes are present), coal mining, transferring diesel fuel, or pesticide spraying are performed.
  • the face mask may also be designed for wearing in hospitals (e.g., performing surgery), distillers and refineries in chemical industries, painting facilities, or oil fields.
  • the face mask may be a surgical face mask or an industrial face mask.
  • the filter media may be incorporated into a variety of other suitable filter elements for use in various applications including gas filtration.
  • the filter media may be used in heating and air conditioning ducts.
  • Filter elements may have any suitable configuration as known in the art including bag filters and panel filters.
  • Filter assemblies for filtration applications can include any of a variety of filter media and/or filter elements.
  • the filter elements can include the above-described filter media and/or layers (e.g., first layer, second layer). Examples of filter elements include gas turbine filter elements, dust collector elements, heavy duty air filter elements, automotive air filter elements, air filter elements for large displacement gasoline engines (e.g., SUVs, pickup trucks, trucks), HVAC air filter elements, HEPA filter elements, ULPA filter elements, and vacuum bag filter elements.
  • Filter elements can be incorporated into corresponding filter systems (gas turbine filter systems, heavy duty air filter systems, automotive air filter systems, HVAC air filter systems (including residential and industrial HVAC air filter systems), HEPA filter systems, ULPA filter system, and vacuum bag filter systems).
  • the filter media can optionally be pleated into any of a variety of configurations (e.g., panel, cylindrical).
  • Filter elements can also be in any suitable form, such as radial filter elements, panel filter elements, or channel flow elements.
  • a radial filter element can include pleated filter media that are constrained within two open wire support materials in a cylindrical shape.
  • the filter element includes a housing that may be disposed around the filter media.
  • the housing can have various configurations, with the configurations varying based on the intended application.
  • the housing may be formed of a frame that is disposed around the perimeter of the filter media.
  • the frame may be thermally sealed around the perimeter.
  • the frame has a generally rectangular configuration surrounding all four sides of a generally rectangular filter media.
  • the frame may be formed from various materials, including for example, cardboard, metal, polymers, or any combination of suitable materials.
  • the filter elements may also include a variety of other features known in the art, such as stabilizing features for stabilizing the filter media relative to the frame, spacers, or any other appropriate feature.
  • the filter media can be incorporated into a bag (or pocket) filter element.
  • a bag filter element may be formed by any suitable method, e.g., by placing two filter media together (or folding a single filter media in half), and mating three sides (or two if folded) to one another such that only one side remains open, thereby forming a pocket inside the filter.
  • multiple filter pockets may be attached to a frame to form a filter element.
  • the filter media and filter elements may have a variety of different constructions and the particular construction depends on the application in which the filter media and elements are used.
  • a substrate may be added to the filter media.
  • the filter elements may have the same property values as those noted above in connection with the filter media and/or layers. For example, the above-noted
  • filter media mechanically trap contaminant particles on the filter media as fluid (e.g., air) flows through the filter media.
  • This example demonstrates the effects of the ratio of a value of thickness over instantaneous resistance of second layer to a value of thickness over instantaneous resistance of first layer on filter media performance.
  • Filter media includes fluorinated SB intervening layer between 1 st and 2" layers
  • SB spunbond, light weight nonwoven polypropylene fiber material as structure reinforcement
  • C50, CI 00, C200 a charged layer made of polypropylene and acrylic fibers of 50, 100, 200 g/m 2 basis weight, respectively
  • Tables 4-5 summarize the various properties of the filter media listed in Table 3.
  • Table 4 summarizes the instantaneous resistance, instantaneous penetration, basis weight, uncompressed thickness, and solidity for the first layer of each filter media listed in Table 3. Table 4.
  • Thickness, resistance ratio of the mil 1 st layer TRF
  • Table 5 summarizes the instantaneous resistance, instantaneous penetration, basis weight, uncompressed thickness, and solidity for the second layer of each filter media listed in Table 3.
  • Table 6 summarizes the total thickness, initial resistance, initial penetration, and the ratio of a value of thickness over instantaneous resistance of the second layer to a value of thickness over instantaneous resistance of first layer (TRF ratio), of the filter media listed in Table 3.
  • TRF ratio the ratio of a value of thickness over instantaneous resistance of the second layer to a value of thickness over instantaneous resistance of first layer
  • This example compares, for different filter media, the effects of a ratio of a value of a basis weight over air permeability of a first layer to a value of a basis weight over air permeability of a second layer and shows the resulting composite air permeability for the filter media.
  • Samples were prepared as listed in Table 7:
  • a first layer comprising a plurality of meltblown fibers (having a range of fiber diameters between 1 and 8 microns) was hand laid on a second, charged layer comprising 50 wt% dry spun acrylic and 50 wt% polypropylene polymer fibers, along with a support layer having an air permeability of greater than 1100 CFM.
  • the first layer had a basis weight of less than 20 g/m and the second layer had a basis weight between
  • filter media 1-6 All three layers of filter media 1-6 were needled together in a single step, with a needle density of at least 10 needle punches per square inch. Filter media 7-10 were not needled together.
  • the composite air permeability values listed in Table 7 for media 7-10 are the equivalent composite air permeability values for each filter media if media 7-10 were needled.
  • the composite air permeability values for media 7-10 were calculated by first measuring the composite air permeability of the unneedled filter media, and then increasing the unneedled composite air permeability value by a calibration factor (in percent) derived from reference needled filter media of varying air permeabilities and basis weights.
  • Filter media 1-10 did not include any adhesive nor any coating of a fluorinated species.
  • Each of filter media 1-6 had a final El efficiency of greater than 36%, an initial resistance of less than 3 mm H 2 0, and a composite air permeability of greater than 200 CFM.
  • Each of filter media 7-10 had a final El efficiency of greater than 36%, an initial resistance of greater than 5 mm H 2 0, and a composite air permeability of less than 200 CFM. Testing for El final efficiency of the filter media was performed according to the ASHRAE 52.2 standard described herein.
  • FIG. 7 shows, for filter media 1-10, the air permeability of the filter media versus the ratio of the value of basis weight over air permeability of the first layer to the value of basis weight over air permeability of the second layer.
  • a reference to "A and/or B,” when used in conjunction with open-ended language such as “comprising” can refer, in some embodiments, to A without B (optionally including elements other than B); in another embodiment, to B without A (optionally including elements other than A); in yet another embodiment, to both A and B (optionally including other elements); etc.
  • the phrase "at least one,” in reference to a list of one or more elements, should be understood to mean at least one element selected from any one or more of the elements in the list of elements, but not necessarily including at least one of each and every element specifically listed within the list of elements and not excluding any combinations of elements in the list of elements.
  • This definition also allows that elements may optionally be present other than the elements specifically identified within the list of elements to which the phrase "at least one" refers, whether related or unrelated to those elements specifically identified.
  • At least one of A and B can refer, in some embodiments, to at least one, optionally including more than one, A, with no B present (and optionally including elements other than B); in another embodiment, to at least one, optionally including more than one, B, with no A present (and optionally including elements other than A); in yet another embodiment, to at least one, optionally including more than one, A, and at least one, optionally including more than one, B (and optionally including other elements); etc.
  • alkane is given its ordinary meaning in the art and refers to a saturated hydrocarbon molecule.
  • amine is given its ordinary meaning in the art and refers to a primary (-NH 2 ), secondary (-NHR X ), tertiary (-NR x R y ), or quaternary (-N + R x R y R z ) amine (e.g., where R x , R y , and R z are independently an aliphatic, alicyclic, alkyl, aryl, or other moieties, as defined herein).

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  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
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Abstract

L'invention concerne également des milieux filtrants pour filtrer des flux gazeux (par exemple, l'air). Dans certains modes de réalisation, les milieux filtrants peuvent être conçus pour présenter des propriétés souhaitables, telles qu'une efficacité de filtration stable, une oléophobie élevée, une faible résistance instantanée et/ou une durée de vie stable. Dans certains modes de réalisation, une ou plusieurs couches du support peuvent avoir une certaine valeur du poids de base sur la perméabilité à l'air (et/ou un rapport d'une valeur du poids de base sur la perméabilité à l'air entre deux couches). Le milieu filtrant peut éventuellement comprendre une couche de support présentant une perméabilité à l'air relativement élevée (par exemple, supérieure ou égale à 1100 CFM). Dans certains cas, le milieu filtrant peut avoir une résistance initiale relativement faible et/ou peut avoir une efficacité El finale particulière. Les milieux filtrants décrits ici peuvent être particulièrement bien appropriés pour des applications qui impliquent la filtration de flux gazeux (par exemple, des masques faciaux, filtration de l'air de la cabine, filtration sous vide, équipement respiratoire, ainsi que les systèmes de chauffage et de climatisation(HVAC) résidentiels et les systèmes HVAC industriels), bien que les milieux puissent également être utilisés dans d'autres applications.
PCT/US2017/043249 2016-07-22 2017-07-21 Milieux de filtration multicouches contenant des électrets WO2018017937A1 (fr)

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WO2018156561A1 (fr) * 2017-02-21 2018-08-30 Hollingsworth & Vose Company Milieu filtrant contenant un électret
EP4194041A1 (fr) 2021-12-08 2023-06-14 Ambu A/S Dispositif médical pour voies respiratoires

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EP4194041A1 (fr) 2021-12-08 2023-06-14 Ambu A/S Dispositif médical pour voies respiratoires

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