WO2015095732A1 - Fibres fibrillées pour milieux de filtration de liquides - Google Patents

Fibres fibrillées pour milieux de filtration de liquides Download PDF

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Publication number
WO2015095732A1
WO2015095732A1 PCT/US2014/071547 US2014071547W WO2015095732A1 WO 2015095732 A1 WO2015095732 A1 WO 2015095732A1 US 2014071547 W US2014071547 W US 2014071547W WO 2015095732 A1 WO2015095732 A1 WO 2015095732A1
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WO
WIPO (PCT)
Prior art keywords
equal
less
fibers
layer
filter media
Prior art date
Application number
PCT/US2014/071547
Other languages
English (en)
Inventor
Howard Yu
Sheha SWAMINATHAN
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 US14/135,187 external-priority patent/US9511330B2/en
Application filed by Hollingsworth & Vose Company filed Critical Hollingsworth & Vose Company
Priority to EP14871285.4A priority Critical patent/EP3083003A4/fr
Priority to CN201480068686.6A priority patent/CN105828904B/zh
Publication of WO2015095732A1 publication Critical patent/WO2015095732A1/fr

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Classifications

    • D—TEXTILES; PAPER
    • D04—BRAIDING; LACE-MAKING; KNITTING; TRIMMINGS; NON-WOVEN FABRICS
    • D04H—MAKING TEXTILE FABRICS, e.g. FROM FIBRES OR FILAMENTARY MATERIAL; FABRICS MADE BY SUCH PROCESSES OR APPARATUS, e.g. FELTS, NON-WOVEN FABRICS; COTTON-WOOL; WADDING ; NON-WOVEN FABRICS FROM STAPLE FIBRES, FILAMENTS OR YARNS, BONDED WITH AT LEAST ONE WEB-LIKE MATERIAL DURING THEIR CONSOLIDATION
    • D04H1/00—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres
    • D04H1/70—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres characterised by the method of forming fleeces or layers, e.g. reorientation of fibres
    • D04H1/72—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres characterised by the method of forming fleeces or layers, e.g. reorientation of fibres the fibres being randomly arranged
    • D04H1/732—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres characterised by the method of forming fleeces or layers, e.g. reorientation of fibres the fibres being randomly arranged by fluid current, e.g. air-lay
    • 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
    • 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
    • B01D39/18—Other self-supporting filtering material ; Other filtering material of organic material, e.g. synthetic fibres the material being cellulose or derivatives thereof
    • D—TEXTILES; PAPER
    • D04—BRAIDING; LACE-MAKING; KNITTING; TRIMMINGS; NON-WOVEN FABRICS
    • D04H—MAKING TEXTILE FABRICS, e.g. FROM FIBRES OR FILAMENTARY MATERIAL; FABRICS MADE BY SUCH PROCESSES OR APPARATUS, e.g. FELTS, NON-WOVEN FABRICS; COTTON-WOOL; WADDING ; NON-WOVEN FABRICS FROM STAPLE FIBRES, FILAMENTS OR YARNS, BONDED WITH AT LEAST ONE WEB-LIKE MATERIAL DURING THEIR CONSOLIDATION
    • D04H1/00—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres
    • D04H1/40—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres from fleeces or layers composed of fibres without existing or potential cohesive properties
    • D04H1/42—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres from fleeces or layers composed of fibres without existing or potential cohesive properties characterised by the use of certain kinds of fibres insofar as this use has no preponderant influence on the consolidation of the fleece
    • D04H1/4374—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres from fleeces or layers composed of fibres without existing or potential cohesive properties characterised by the use of certain kinds of fibres insofar as this use has no preponderant influence on the consolidation of the fleece using different kinds of webs, e.g. by layering webs
    • D—TEXTILES; PAPER
    • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
    • D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
    • D21H11/00—Pulp or paper, comprising cellulose or lignocellulose fibres of natural origin only
    • D21H11/16—Pulp or paper, comprising cellulose or lignocellulose fibres of natural origin only modified by a particular after-treatment
    • D21H11/18—Highly hydrated, swollen or fibrillatable fibres
    • D—TEXTILES; PAPER
    • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
    • D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
    • D21H13/00—Pulp or paper, comprising synthetic cellulose or non-cellulose fibres or web-forming material
    • D21H13/02—Synthetic cellulose fibres
    • D—TEXTILES; PAPER
    • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
    • D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
    • D21H13/00—Pulp or paper, comprising synthetic cellulose or non-cellulose fibres or web-forming material
    • D21H13/10—Organic non-cellulose fibres
    • D21H13/20—Organic non-cellulose fibres from macromolecular compounds obtained otherwise than by reactions only involving carbon-to-carbon unsaturated bonds
    • D21H13/26—Polyamides; Polyimides
    • D—TEXTILES; PAPER
    • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
    • D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
    • D21H27/00—Special paper not otherwise provided for, e.g. made by multi-step processes
    • D21H27/30—Multi-ply
    • 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
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B27—WORKING OR PRESERVING WOOD OR SIMILAR MATERIAL; NAILING OR STAPLING MACHINES IN GENERAL
    • B27N—MANUFACTURE BY DRY PROCESSES OF ARTICLES, WITH OR WITHOUT ORGANIC BINDING AGENTS, MADE FROM PARTICLES OR FIBRES CONSISTING OF WOOD OR OTHER LIGNOCELLULOSIC OR LIKE ORGANIC MATERIAL
    • B27N3/00—Manufacture of substantially flat articles, e.g. boards, from particles or fibres
    • B27N3/04—Manufacture of substantially flat articles, e.g. boards, from particles or fibres from fibres
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29L—INDEXING SCHEME ASSOCIATED WITH SUBCLASS B29C, RELATING TO PARTICULAR ARTICLES
    • B29L2031/00—Other particular articles
    • B29L2031/14—Filters

Definitions

  • aspects described herein relate generally to fiber webs that include fibrillated fibers that can be used in filter media.
  • Filter media can be used to remove contamination in a variety of applications.
  • filter media include one or more fiber webs.
  • the fiber web provides a porous structure that permits fluid (e.g., fuel, lube, hydraulic fluid, air) to flow through the web. Contaminant particles contained within the fluid may be trapped on the fiber web.
  • Fiber web characteristics e.g., fiber dimensions, fiber composition, basis weight, amongst others
  • mechanical properties e.g., elongation, strength, amongst others
  • filtration performance e.g., dust holding capacity, liquid filtration efficiency, amongst others).
  • Certain filter media include webs that comprise glass fibers. While often having desirable filtration performance, glass fiber webs may exhibit limited strength and brittle characteristics which can lead to fiber shedding during handling, further processing (e.g., pleating, slitting), installation, and use. The presence of glass fibers in filter media may also give rise to environmental concerns.
  • Fibers webs that include fibrillated fibers and can be used in filter media are described herein.
  • a series of filter media are provided.
  • a filter media comprises a wet laid fiber web comprising a plurality of synthetic fibers.
  • the wet laid fiber web has a [mean flow pore ⁇ m)/(permeability (cfm/sf)) 0'5 ] value of less than or equal to about 3.0.
  • the wet laid fiber web comprises between about 0 wt% to about 10 wt of glass fibers.
  • the filter media has an basis weight of greater than about 10 g/m 2 and less than or equal to about 1000 g/m 2 , and a thickness of between about 0.1 mm and about 10.0 mm.
  • a filter media comprises a fiber web comprising a plurality of synthetic fibers.
  • the fiber web has a [mean flow pore ⁇ m)/(permeability (cfm/sf)) 0'5 ] value of less than about 3.0.
  • the fiber web has a dust holding capacity of greater than or equal to about 80 g/m 2 , wherein the dust holding capacity is measured using a Multipass Filter Tests at a 25 mg/L base upstream gravimetric level (BUGL), a face velocity of 0.06 cm/s, and a 100 kPa terminal pressure following the ISO 16889/19438 procedure.
  • the wet laid fiber web comprises between about 0 wt% to about 10 wt% of glass fibers.
  • the filter media has an basis weight of greater than about 10 g/m 2 and less than or equal to about 1000 g/m 2 and a thickness of between about 0.1 mm and about 10 mm.
  • a filter media comprises a fiber web comprising a plurality of fibrillated fibers.
  • the fiber web comprises about 0 wt% to about 10 wt% of glass fibers.
  • the filter media has a liquid filtration efficiency of at least 98% for 4 microns or greater particles, wherein the efficiency is measured using a Multipass Filter Tests at a 25 mg/L base upstream gravimetric level (BUGL), a face velocity of 0.06 cm s, and a 100 kPa terminal pressure following the ISO 16889/19438 procedure.
  • BUGL base upstream gravimetric level
  • the filter media has a basis weight of greater than about 10 g/m 2 and less than or equal to about 1000 g/m 2 , and a thickness of between about 0.1 mm and about 10 mm.
  • a filter media comprises a first layer comprising a plurality of organic polymer fibers, and a second layer comprising greater than or equal to about 60 wt% fibrillated fibers.
  • the first layer has a first basis weight of greater than or equal to about 10 g/m 2 and less than about 300 g/m 2 .
  • the second layer has a second basis weight of greater than or equal to about 3 g/m 2 and less than about 200 g/m 2 .
  • the ratio of the first basis weight to the second basis weight is at least 3: 1 and less than 14: 1.
  • the filter media has a thickness of between about 0.3 mm and about 10 mm.
  • a filter media comprises a first layer and a second layer in combination with an additional layer (e.g., a third layer).
  • the first layer and/or second layer is a wet laid layer (e.g., a layer formed by a wet laid process).
  • the additional layer is a non-wet laid layer (e.g., a layer formed by a non-wet laid process) and may include meltblown fibers, meltspun fibers, centrifugal spun fibers, or fibers formed by other non-wet laid processes.
  • the first layer comprises a plurality of organic polymer fibers
  • the second layer comprises a plurality of synthetic fibers.
  • At least one of the first and second layers includes fibrillated fibers (e.g., between about 1 wt% and about 100 wt% of the first and/or second layers).
  • the first and/or second layers comprises between about 0 wt% to about 10 wt of glass fibers.
  • the additional layer includes synthetic polymer fibers.
  • the filter media can achieve a fuel- water separation efficiency of at least about 30% (e.g., between about 60% to about 99.9%).
  • the first and/or second layer may be a non-wet laid layer (e.g., formed of meltblown fibers, meltspun fibers, dry laid (carded) fibers, centrifugal spun fibers, spunbond fibers, and/or air laid fibers) as described herein.
  • a non-wet laid layer e.g., formed of meltblown fibers, meltspun fibers, dry laid (carded) fibers, centrifugal spun fibers, spunbond fibers, and/or air laid fibers
  • the additional layer may have a basis weight of between about 5 g/m 2 and about 800 g/m 2 , an air permeability of less than about 1300 cfm/sf, and an average fiber diameter of less than 100 microns.
  • the overall filter media may have a basis weight of greater than about 10 g/m 2 and less than or equal to about 1000 g/m 2 , a thickness of between about 0.1 mm and about 10.0 mm.
  • the filter media can achieve an efficiency at 4 microns of at least 99%, an initial efficiency of at least 99%, and a dust holding capacity of at least 150 gsm.
  • FIG. 1 is a schematic diagram showing a fiber web according to one set of embodiments.
  • Fiber webs which are used in filter media are described herein.
  • the fiber webs include fibrillated fibers and optionally non-fibrillated fibers, amongst other optional components (e.g., binder resin).
  • the fiber webs include limited amounts of, or no, glass fiber. The respective
  • characteristics and amounts of the fibrillated fibers are selected to impart desirable properties including mechanical properties and filtration properties (e.g., dust holding capacity and efficiency), amongst other benefits.
  • Filter media formed of the webs may be particularly well- suited for applications that involve filtering fuel, though the media may also be used in other applications (e.g., for filtering lube, hydraulic fluids, air).
  • the fiber webs described herein may include multiple layers, though other arrangements are possible.
  • the use of fibrillated fibers can increase the surface area of the fiber web, leading to an improvement in one or more properties of the media such as increased particle capture efficiency and/or dust holding capacity.
  • the use of fibrillated fibers may also lead to a decrease in the mean pore size of the fiber web compared to a fiber web having similar properties (e.g., basis weight, fiber type, etc.) but absent fibrillated fibers. Accordingly, a fiber web including such fibrillated fibers may have a relatively low pressure drop while achieving an increased efficiency per unit thickness.
  • the fiber webs described herein can achieve such improved properties with limited amounts of, or no, glass fibers.
  • the fiber webs described herein may have a single layer, or multiple layers. In some embodiments involving multiple layers, a clear demarcation of layers may not always be apparent, as described in more detail below.
  • An example of a fiber web is shown in FIG. 1.
  • a fiber web 10 includes a first layer 15 and a second layer 20 having a combined thickness 25.
  • the fiber web may include additional layers (not shown).
  • the first layer may be positioned upstream or downstream of the second layer in a filter element.
  • the first layer is a relatively open layer (e.g., having a relatively higher air permeability) compared to the second layer
  • the second layer is a relatively tight layer (e.g., having a relatively lower air permeability) compared to the first layer.
  • the first layer is a relatively tight layer compared to the first layer
  • the second layer is a relatively open layer compared to the second layer.
  • one or more fibrillated fibers may be present in at least one layer of the fiber web, such as in the first layer, in the second layer, in both layers, or in all layers.
  • the first layer may be constructed to have a relatively high dust holding capacity.
  • the first layer may also be constructed to have a relatively high filtration efficiency in some cases.
  • the first layer may include fibrillated fibers in some embodiments, but does not include fibrillated fibers in other
  • the first layer may be positioned upstream of the second layer in a filter element.
  • the second layer includes one or more fibrillated fibers and is constructed to achieve a relatively high filtration efficiency.
  • the second layer may also have good dust holding properties in some embodiments.
  • the second layer may be positioned downstream of the first layer in a filter element.
  • the properties of the fiber web may be tailored by varying the amount of fibrillated fibers, the type of fibrillated fibers, and/or the level of fibrillation of the fibers present in one or more layers of the fiber web. Examples of suitable types, amounts, and levels of fibrillation for fibrillated fibers in each of the layers are provided below.
  • a fiber web may include a third layer positioned directly adjacent the first layer (e.g., on the side opposite the second layer), directly adjacent the second layer (e.g., on the side opposite the first layer), or between the first and second layers. Additional layers are also possible.
  • an additional layer e.g., a third layer, a fourth layer, etc.
  • strength e.g., Mullen burst strength, tensile strength, elongation
  • any additional layers may have any of the features or properties described herein for the first or second layers.
  • fiber web 10 includes a clear demarcation between the first and second layers.
  • the fiber web may include an interface 40 between the two layers that is distinct.
  • the first and second layers may be formed separately, and combined by any suitable method such as lamination, collation, or by use of adhesives.
  • the first and second layers (and any additional layer(s)) may be formed using different processes, or the same process.
  • each of the first and second layers (and any additional layer(s)) may be independently formed by a wet laid process, a non-wet laid process (e.g., a dry laid process, a spinning process, a meltblown process), or any other suitable process.
  • fiber web 10 does not include a clear demarcation between the first and second layers.
  • a distinct interface between the two layers may not be apparent.
  • the layers forming a fiber web may be indistinguishable from one another across the thickness of the fiber web.
  • the first and second layers may be formed by the same process (e.g., a wet laid process, a non-wet laid process (e.g., a dry laid process, a spinning process, a meltblown process), or any other suitable process) or by different processes in such embodiments. In some instances, the first and second layers may be formed simultaneously.
  • fiber web 10 includes a gradient (i.e., a change) in one or more properties such as amount of fibrillated fiber, level of fibrillation of fibers, fiber diameter, fiber type, fiber composition, fiber length, fiber surface chemistry, pore size, material density, basis weight, solidity, a proportion of a component (e.g., a binder, resin, crosslinker), stiffness, tensile strength, wicking ability, hydrophilicity/hydrophobicity, and conductivity across a portion, or all of, the thickness of the fiber web.
  • a gradient i.e., a change in one or more properties such as amount of fibrillated fiber, level of fibrillation of fibers, fiber diameter, fiber type, fiber composition, fiber length, fiber surface chemistry, pore size, material density, basis weight, solidity, a proportion of a component (e.g., a binder, resin, crosslinker), stiffness, tensile strength, wicking ability, hydrophilicity/hydrophobicity, and conduct
  • Fiber webs suitable for use as filter media may optionally include a gradient in one or more performance characteristics such as efficiency, dust holding capacity, pressure drop, permeability, and porosity across the thickness of the fiber web.
  • a gradient in one or more such properties may be present in the fiber web between a top surface 30 and a bottom surface 35 of the fiber web.
  • a gradient in one or more properties is gradual (e.g., linear, curvilinear) between a top surface and a bottom surface of the fiber web.
  • the fiber web may have an increasing amount of fibrillated fiber from the top surface to the bottom surface of the fiber web.
  • a fiber web may include a step gradient in one more properties across the thickness of the fiber web.
  • the transition in the property may occur primarily at interface 40 between the two layers.
  • a fiber web e.g., having a first layer including a first fiber type and a second layer including a second fiber type, may have an abrupt transition between fiber types across the interface. In other words, each of the layers of the fiber web may be relatively distinct.
  • Other types of gradients are also possible.
  • a fiber web may include a gradient in one or more properties through portions of the thickness of the fiber web. In the portions of the fiber web where the gradient in the property is not present, the property may be substantially constant through that portion of the web. As described herein, in some instances a gradient in a property involves different proportions of a component (e.g., a type of fiber such as a fibrillated fiber, hardwood fibers, softwood fibers, an additive, a binder) across the thickness of a fiber web. In some embodiments, a component may be present at an amount or a concentration that is different than another portion of the fiber web. In other embodiments, a component is present in one portion of the fiber web, but is absent in another portion of the fiber web. Other configurations are also possible.
  • a component e.g., a type of fiber such as a fibrillated fiber, hardwood fibers, softwood fibers, an additive, a binder
  • a fiber web has a gradient in one or more properties in two or more regions of the fiber web.
  • a fiber web including three layers may have a first gradient in one property across the first and second layer, and a second gradient in another property across the second and third layers.
  • the first and second gradients may be the same in some embodiments, or different in other embodiments (e.g., characterized by a gradual vs. an abrupt change in a property across the thickness of the fiber web). Other configurations are also possible.
  • a fiber web may include any suitable number of layers, e.g., at least 2, 3, 4, 5, 6, 7, 8, or 9 layers depending on the particular application and performance characteristics desired. It should be appreciated that in some embodiments, the layers forming a fiber web may be indistinguishable from one another across the thickness of the fiber web. As such, a fiber web formed from, for example, two “layers” or two “fiber mixtures” can also be characterized as having a single "layer” (or a "composite” layer) having a gradient in a property across the fiber web in some instances. Such composite layers may optionally be combined with additional layers in the fiber web to form, for example, fiber webs having a gradient in one or more properties in certain portions of the fiber web, but not in other portions of the fiber web.
  • the first layer of fiber web 10 of FIG. 1 does not include a gradient of a property across the thickness of the first layer, but the second layer does include a gradient of a property across the thickness of the second layer.
  • the first layer of fiber web 10 of FIG. 1 includes a gradient of a property across the thickness of the first layer, but the second layer does not include a gradient of a property across the thickness of the second layer.
  • both the first layer and the second layer includes a gradient of one or more properties across the thicknesses of the layers. Other configurations are also possible.
  • the one or more properties varying across the thickness of a layer may include, for example, a concentration of a fibrillated fiber, level of fibrillation of fibers, fiber type (e.g., type of fibrillated fiber), fiber diameter, fiber composition, fiber length, fiber surface chemistry, pore size, material density, basis weight, solidity, a proportion of a component (e.g., a binder, resin, crosslinker), stiffness, tensile strength, wicking ability, hydrophilicity/hydrophobicity, and/or conductivity.
  • a concentration of a fibrillated fiber e.g., level of fibrillation of fibers
  • fiber type e.g., type of fibrillated fiber
  • fiber diameter fiber composition
  • fiber length fiber length
  • fiber surface chemistry e.g., pore size
  • material density e.g., basis weight
  • solidity e.g., a proportion of a component
  • a component e.g., a binder, resin, crosslink
  • the fiber webs described herein include one or more fibrillated fibers.
  • a fibrillated fiber includes a parent fiber that branches into smaller diameter fibrils which can, in some instances, branch further out into even smaller diameter fibrils with further branching also being possible.
  • the branched nature of the fibrils leads to a fiber web having a high surface area and can increase the number of contact points between the fibrillated fibers and other fibers in the web. Such an increase in points of contact between the fibrillated fibers and other fibers and/or components of the web may contribute to enhancing mechanical properties (e.g., flexibility, strength) and/or filtration performance properties of the fiber web.
  • the fibrillated fibers included in a fiber web may have any suitable level of fibrillation.
  • the level of fibrillation relates to the extent of branching in the fiber.
  • the average level of fibrillation of fibers may vary between different layers in a multi-layered fiber web.
  • a first layer may include fibers having a relatively low level of fibrillation compared to the fibers of a second layer.
  • a first layer may include fibers having a relatively high level of fibrillation compared to the fibers of a second layer.
  • the average level of fibrillation may vary in a layer (or vary in the entire web) depending on whether the layer (or web) includes a single type of fibrillated fiber or more than one type of fibrillated fiber. The same fiber type, but fibers fibrillated to different extents, may also be used in one or more layers of the fiber web.
  • the level of fibrillation may be measured according to any number of suitable methods.
  • the level of fibrillation of the fibrillated fibers can be measured according to a Canadian Standard Freeness (CSF) test, specified by TAPPI test method T 227 om 09 Freeness of pulp.
  • CSF Canadian Standard Freeness
  • the test can provide an average CSF value.
  • the average CSF value of the fibrillated fibers used in a fiber web may vary between about 10 mL and about 750 mL.
  • the average CSF value of the fibrillated fibers used in a fiber web may be greater than or equal to 1 mL, greater than or equal to about 10 mL, greater than or equal to about 20 mL, greater than or equal to about 35 mL, greater than or equal to about 45 mL, greater than or equal to about 50 mL, greater than or equal to about 65 mL, greater than or equal to about 70 mL, greater than or equal to about 75 mL, greater than or equal to about 80 mL, greater than or equal to about 100 mL, greater than or equal to about 150 mL, greater than or equal to about 175 mL, greater than or equal to about 200 mL, greater than or equal to about 250 mL, greater than or equal to about 300 mL, greater than or equal to about 350 mL, greater than or equal to about 500 mL, greater than or equal to about 600 mL, greater than or equal to about 650 mL, greater than or equal to about 700 m
  • the average CSF value of the fibrillated fibers used in a fiber web may be less than or equal to about 800 mL, less than or equal to about 750 mL, less than or equal to about 700 mL, less than or equal to about 650 mL, less than or equal to about 600 mL, less than or equal to about 550 mL, less than or equal to about 500 mL, less than or equal to about 450 mL, less than or equal to about 400 mL, less than or equal to about 350 mL, less than or equal to about 300 mL, less than or equal to about 250 mL, less than or equal to about 225 mL, less than or equal to about 200 mL, less than or equal to about 150 mL, less than or equal to about 100 mL, less than or equal to about 90 mL, less than or equal to about 85 mL, less than or equal to about 70 mL, less than or equal to about 50 mL, less than or equal to
  • an average CSF value of fibrillated fibers of greater than or equal to about 10 mL and less than or equal to about 300 mL are also possible.
  • the average CSF value of the fibrillated fibers used in a fiber web may be based on one type of fibrillated fiber or more than one type of fibrillated fiber.
  • the level of fibrillation of the fibrillated fibers can be measured according to a Schopper Riegler (SR) test.
  • the average SR value of the fibrillated fibers may be greater than about 20 ° SR, greater than about 30 ° SR, greater than about 40°SR, greater than about 50°SR, or greater than about 60° SR.
  • the average SR value of the fibrillated fibers may be less than about 80 °SR, less than about 70°SR, less than about 60 °SR, less than about 50°SR, or less than about 40 ° SR. It can be appreciated that the average SR values may be between any of the above-noted lower limits and upper limits.
  • the average SR value of the fibrillated fibers may be between about 20 ° SR and about 70 ° SR, between about 20°SR and about 60°SR, or between about 30°SR and about 50°SR, between about 32 0 SR and about 52 ° SR, or between about 40 ° SR and about 50 0 SR.
  • the fibers may have fibrillation levels outside the above-noted ranges.
  • the average CSF value of fibrillated fibers (if present) in each of the layers may vary.
  • the average CSF value of the fibrillated fibers in the first layer may vary between about 10 mL and about 750 mL.
  • the average CSF value of the fibrillated fibers used in a first layer may be greater than or equal to 1 mL, greater than or equal to about 10 mL, greater than or equal to about 20 mL, greater than or equal to about 35 mL, greater than or equal to about 45 mL, greater than or equal to about 50 mL, greater than or equal to about 65 mL, greater than or equal to about 70 mL, greater than or equal to about 75 mL, greater than or equal to about 80 mL, greater than or equal to about 100 mL, greater than or equal to about 150 mL, greater than or equal to about 175 mL, greater than or equal to about 200 mL, greater than or equal to about 250 mL, greater than or equal to about 300 mL, greater than or equal to about 350 mL, greater than or equal to about 500 mL, greater than or equal to about 600 mL, greater than or equal to about 650 mL, greater than or equal to about 700 m
  • the average CSF value of the fibrillated fibers used in a first layer may be less than or equal to about 750 mL, less than or equal to about 700 mL, less than or equal to about 650 mL, less than or equal to about 600 mL, less than or equal to about 550 mL, less than or equal to about 500 mL, less than or equal to about 450 mL, less than or equal to about 400 mL, less than or equal to about 350 mL, less than or equal to about 300 mL, less than or equal to about 250 mL, less than or equal to about 225 mL, less than or equal to about 200 mL, less than or equal to about 150 mL, less than or equal to about 100 mL, less than or equal to about 90 mL, less than or equal to about 85 mL, less than or equal to about 70 mL, less than or equal to about 50 mL, less than or equal to about 40 mL, or less than or equal to about 750
  • an average CSF value of fibrillated fibers of greater than or equal to about 10 mL and less than or equal to about 300 mL are also possible.
  • the average CSF value of the fibrillated fibers used in a first layer may be based on one type of fibrillated fiber or more than one type fibrillated fiber.
  • the average CSF value of the fibrillated fibers in the second layer may vary between about 10 mL and about 750 mL.
  • the average CSF value of the fibrillated fibers used in a second layer may be greater than or equal to 1 mL, greater than or equal to about 10 mL, greater than or equal to about 20 mL, greater than or equal to about 35 mL, greater than or equal to about 45 mL, greater than or equal to about 50 mL, greater than or equal to about 65 mL, greater than or equal to about 70 mL, greater than or equal to about 75 mL, greater than or equal to about 80 mL, greater than or equal to about 100 mL, greater than or equal to about 150 mL, greater than or equal to about 175 mL, greater than or equal to about 200 mL, greater than or equal to about 250 mL, greater than or equal to about 300 mL, greater than or equal to about 350 mL, greater than or equal to about 150 mL, greater than
  • the average CSF value of the fibrillated fibers used in a second layer may be less than or equal to about 750 mL, less than or equal to about 700 mL, less than or equal to about 650 mL, less than or equal to about 600 mL, less than or equal to about 550 mL, less than or equal to about 500 mL, less than or equal to about 450 mL, less than or equal to about 400 mL, less than or equal to about 350 mL, less than or equal to about 300 mL, less than or equal to about 250 mL, less than or equal to about 225 mL, less than or equal to about 200 mL, less than or equal to about 150 mL, less than or equal to about 100 mL, less than or equal to about 90 mL, less than or equal to about 85 mL, less than or equal to about 70 mL, less than or equal to about 50 mL, less than or equal to about 40 mL, or less than or equal to about 750
  • an average CSF value of fibrillated fibers of greater than or equal to about 10 mL and less than or equal to about 300 mL are also possible.
  • the average CSF value of the fibrillated fibers used in a second layer may be based on one type of fibrillated fiber or more than one type fibrillated fiber.
  • a fibrillated fiber may be formed of any suitable materials such as synthetic materials (e.g., synthetic polymers such as polyester, polyamide, polyaramid, para- aramid, meta-aramid, polyimide, polyethylene, polypropylene, polyether ether ketone, polyethylene terephthalate, polyolefin, nylon, acrylics, regenerated cellulose (e.g., lyocell, rayon), liquid crystal polymers (e.g., poly p-phenylene-2,6-bezobisoxazole (PBO), polyester-based liquid crystal polymers such as polyesters produced by the polycondensation of 4-hydroxybenzoic acid and 6-hydroxynaphthalene-2-carboxylic acid), and natural materials (e.g., natural polymers such as cellulose (e.g., non- regenerated cellulose), organic fibers such as wool).
  • synthetic materials e.g., synthetic polymers such as polyester, polyamide, polyaramid, para- aramid, meta-aramid, polyimide
  • fibrillated fibers may be synthetic fibers.
  • Synthetic fibers as used herein, are non-naturally occurring fibers formed of polymeric material.
  • Fibrillated fibers may also be non-synthetic fibers, for example, cellulose fibers that are naturally occurring.
  • Cellulose fibers may include, for example, wood cellulose fibers and non-wood cellulose fibers. It can be appreciated that fibrillated fibers may include any suitable combination of synthetic and/or non- synthetic fibers.
  • the fibrillated fibers are formed of lyocell.
  • Lyocell fibers are known to those of skill in the art as a type of synthetic fiber and may be produced from regenerated cellulose by solvent spinning.
  • the fibrillated fibers are formed of rayon.
  • Rayon fibers are known to those of ordinary skill in the art. They are also produced from regenerated cellulose and may be produced using an acetate method, a cuprammonium method, or a viscose process. In these methods, the cellulose or cellulose solution may be spun to form fibers. Fibers may be fibrillated through any appropriate fibrillation refinement process. In some embodiments, fibers are fibrillated using a disc refiner, a stock beater or any other suitable fibrillating equipment.
  • the fibrillated fibers may have compositions other than those described above.
  • suitable compositions may include acrylic, liquid crystalline polymers, polyoxazole (e.g., poly(p-phenylene- 2,6-benzobisoxazole), aramid, paramid, cellulose wood, cellulose non-wood, cotton, polyethylene, polyolefin and olefin, amongst others.
  • the fibrillated fibers may have any suitable dimensions (e.g., dimensions measured via a microscope).
  • fibrillated fibers include parent fibers and fibrils.
  • the parent fibers may have an average diameter of, for example, between about 1 micron about 75 microns. In some embodiments, the parent fibers may have an average diameter of less than or equal to about 75 microns, less than or equal to about 60 microns, less than or equal to about 50 microns, less than or equal to about 40 microns, less than or equal to about 30 microns, less than or equal to about 20 microns, or less than or equal to about 15 microns.
  • the parent fibers may have an average diameter of greater than or equal to about 10 microns, greater than or equal to about 15 microns, greater than or equal to about 20 microns, greater than or equal to about 30 microns, greater than or equal to about 40 microns, greater than or equal to about 50 microns, greater than or equal to about 60 microns, or greater than or equal to about 75 microns. Combinations of the above referenced ranges are also possible (e.g., parent fibers having an average diameter of greater than or equal to about 15 microns and less than about 75 microns). Other ranges are also possible.
  • the fibrils may have an average diameter of, for example, between about 0.2 micron about 15 microns. In some embodiments, the fibrils may have an average diameter of less than or equal to about 15 microns, less than or equal to about 10 microns, less than or equal to about 8 microns, less than or equal to about 6 microns, less than or equal to about 4 microns, less than or equal to about 3 microns, less than or equal to about 2 microns, or less than or equal to about 1 micron.
  • the fibrils may have an average diameter of greater than or equal to about 0.2 microns, greater than or equal to about 1 micron, greater than or equal to about 2 microns, greater than or equal to about 3 microns, greater than or equal to about 4 microns, greater than or equal to about 6 microns, greater than or equal to about 8 microns, or greater than or equal to about 10 microns. Combinations of the above referenced ranges are also possible (e.g., fibrils having an average diameter of greater than or equal to about 3 microns and less than about 6 microns). Other ranges are also possible.
  • the fibrillated fibers described may have an average length of, for example, between about 1 mm and about 15 mm (e.g., between about 0.2 and about 12 mm, or between about 2 mm and about 4 mm). In some embodiments, the average length of a fibrillated fiber may be less than or equal to about 15 mm, less than or equal to about 12 mm, less than or equal to about 10 mm, less than or equal to about 8 mm, less than or equal to about 6 mm, less than or equal to about 4 mm, or less than or equal to about 2 mm.
  • the average length of a fibrillated fiber may be greater than or equal to about 2 mm, greater than or equal to about 4 mm, greater than or equal to about 6 mm, greater than or equal to about 8 mm, greater than equal to about 10 mm, or greater than or equal to about 12 mm. Combinations of the above referenced ranges are also possible (e.g., fibrillated fibers having an average length of greater than or equal to about 2 mm and less than about 12 mm). Other ranges are also possible.
  • the average length of the fibrillated fibers refers to the average length of parent fibers from one end to an opposite end of the parent fibers. In some embodiments, the maximum average length of the fibrillated fibers fall within the above-noted ranges.
  • the maximum average length refers to the average of the maximum dimension along one axis of the fibrillated fibers (including parent fibers and fibrils).
  • the above-noted dimensions may be, for example, when the fibrillated fibers are lyocell or when the fibrillated fibers are a material other than lyocell. It should be understood that, in certain embodiments, the fibers and fibrils may have dimensions outside the above-noted ranges.
  • the fiber web may include any suitable weight percentage of fibrillated fibers to achieve the desired balance of properties.
  • the weight percentage of the fibrillated fibers in the fiber web is between about 1 wt% and about 100 wt (e.g., between about 2 wt% and about 60 wt ).
  • the weight percentage of fibrillated fibers in the fiber web may be greater than or equal to about 2 wt , greater than or equal to about 5 wt%, greater than or equal to about 10 wt%, greater than or equal to about 15 wt , greater than or equal to about 20 wt , greater than or equal to about 25 wt , greater than or equal to about 30 wt , greater than or equal to about 35 wt%, greater than or equal to about 40 wt%, greater than or equal to about 45 wt%, greater than or equal to about 50 wt%, or greater than or equal to about 60 wt%.
  • the weight percentage of the fibrillated fibers in the web is less than or equal to about 100 wt%, less than or equal to about 90 wt%, less than or equal to about 80 wt%, less than or equal to about 70 wt%, less than or equal to about 60 wt%, less than or equal to about 55 wt%, less than or equal to about 50 wt%, less than or equal to about 45 wt%, less than or equal to about 40 wt%, less than or equal to about 35 wt%, less than or equal to about 30 wt%, less than or equal to about 25 wt%, less than or equal to about 20 wt , less than or equal to about 15 wt%, less than or equal to about 10 wt%, or less than or equal to about 5 wt%. Combinations of the above -referenced ranges are also possible (e.g., a weight percentage of greater than about 2 wt% and less than or equal to about 25 wt%,
  • fiber webs having an amount of fibrillated fibers that is greater than that of other fiber webs may exhibit a comparatively greater degree of flexibility and strength, for example, an increased elongation, tensile strength and/or burst strength than the other fiber webs.
  • a fiber web or a layer within a fiber web includes fibrillated fibers having a relatively high degree of fibrillation.
  • lower amounts of fibrillated fiber may be needed in order to achieve the same structural and/or performance characteristics as a fiber web including fibrillated fibers having a relatively lower degree of fibrillation but larger amounts of such fibers.
  • a fiber web or a layer within a fiber web includes fibrillated fibers having an average CSF value of greater than or equal to about 10 mL and less than or equal to about 300 mL, less than or equal to about 250 mL, less than or equal to about 225 mL, less than or equal to about 200 mL, less than or equal to about 150 mL, less than or equal to about 100 mL, less than or equal to about 90 mL, less than or equal to about 85 mL, less than or equal to about 70 mL, less than or equal to about 50 mL, less than or equal to about 40 mL, or less than or equal to about 25 mL.
  • the weight percentage of fibrillated fibers in such a fiber web or layer within the fiber web may be, for example, greater than or equal to about 2 wt% (e.g., greater than or equal to about 5 wt%, greater than or equal to about 10 wt%, greater than or equal to about 15 wt%, greater than or equal to about 20 wt , greater than or equal to about 25 wt , greater than or equal to about 30 wt , greater than or equal to about 35 wt%, greater than or equal to about 40 wt%, greater than or equal to about 45 wt%, greater than or equal to about 50 wt%, greater than or equal to about 60 wt .
  • a fiber web includes at least first and second layers, such as in the embodiment shown illustratively in FIG. 1, the weight percentage of fibrillated fibers in each of the layers may also vary. For example, in some
  • the weight percentage of fibrillated fibers in the first layer may be between about 0 wt% and about 100 wt%. In some embodiments, the weight percentage of fibrillated fibers in the first layer of the fiber web may be greater than or equal to about 2 wt , greater than or equal to about 10 wt , greater than or equal to about 20 wt , greater than or equal to about 40 wt%, greater than or equal to about 60 wt%, or greater than or equal to about 80 wt%.
  • the weight percentage of the fibrillated fibers in the first layer may be less than or equal to about 100 wt%, less than or equal to about 80 wt%, less than or equal to about 40 wt%, less than or equal to about 20 wt%, less than or equal to about 10 wt%, or less than or equal to about 5 wt%.
  • Combinations of the above-referenced ranges are also possible (e.g., a weight percentage of greater than about 2 wt% and less than or equal to about 100 wt ). Other ranges are also possible.
  • the weight percentage of fibrillated fibers in the second layer may be between about 0 wt% and about 100 wt%. In some embodiments, the weight percentage of fibrillated fibers in the second layer of the fiber web may be greater than or equal to about 1 wt%, greater than or equal to about 2 wt%, greater than or equal to about 5 wt%, greater than or equal to about 10 wt%, greater than or equal to about 20 wt , greater than or equal to about 30 wt , greater than or equal to about 40 wt , greater than or equal to about 50 wt%, greater than or equal to about 60 wt%, greater than or equal to about 70 wt%, greater than or equal to about 80 wt%, or greater than or equal to about 90 wt%,.
  • the weight percentage of the fibrillated fibers in the second layer may be less than or equal to about 100 wt%, less than or equal to about 90 wt%, less than or equal to about 80 wt%, less than or equal to about 70 wt%, less than or equal to about 60 wt%, less than or equal to about 50 wt%, less than or equal to about 40 wt%, less than or equal to about 30 wt%, less than or equal to about 20 wt%, less than or equal to about 15 wt%, less than or equal to about 10 wt%, or less than or equal to about 5 wt%. Combinations of the above-referenced ranges are also possible (e.g., a weight percentage of greater than about 5 wt% and less than or equal to about 100 wt%). Other ranges are also possible.
  • the amount of fibrillated fibers and the level of fibrillation may vary between fiber web layers of the filter media.
  • the relative amount of fibrillated fibers and the level of fibrillation may vary when a first layer of a filter media is an upstream layer and a second layer of the filter media is a downstream layer.
  • an upstream layer has a lesser degree of fibrillation (i.e., greater average CSF) than a downstream layer.
  • an upstream layer has a greater degree of fibrillation than a downstream layer.
  • the percentage of fibrillated fibers in an upstream layer is comparatively smaller than the percentage of fibrillated fibers in a downstream layer.
  • the percentage of fibrillated fibers in an upstream layer is greater than the percentage of fibrillated fibers in a downstream layer.
  • the second layer may include more fibrillated fibers than the first layer (e.g., at least 10%, at least 20%, at least 40%, at least 60%, at least 80%, at least 100%, at least 150%, at least 200%, at least 300%, at least 400%, at least 500%, or at least 1000% more fibrillated fibers than the first layer).
  • the first layer may include more fibrillated fibers than the second layer (e.g., at least 10%, at least 20%, at least 40%, at least 60%, at least 80%, at least 100%, at least 150%, at least 200%, at least 300%, at least 400%, at least 500%, or at least 1000% more fibrillated fibers than the second layer).
  • fibrillated fibers e.g., at least 10%, at least 20%, at least 40%, at least 60%, at least 80%, at least 100%, at least 150%, at least 200%, at least 300%, at least 400%, at least 500%, or at least 1000% more fibrillated fibers than the second layer.
  • Other ranges are also possible.
  • the same amount of fibrillated fibers are present in each of the layers. Gradients of amounts of fibrillated fibers may also be present across the thickness of the fiber web.
  • the second layer may include fibrillated fibers having a higher average level of fibrillation than the fibrillated fibers of the first layer.
  • the average CSF value of the fibrillated fibers of the second layer may be at least 10%, at least 20%, at least 40%, at least 60%, at least 80%, at least 100%, at least 150%, at least 200%, at least 300%, at least 400%, or at least 500% greater than the average CSF value of the fibrillated fibers of the first layer.
  • the first layer may include fibrillated fibers having a higher average level of fibrillation than the fibrillated fibers of the second layer.
  • the average CSF value of the fibrillated fibers of the first layer may be at least 10%, at least 20%, at least 40%, at least 60%, at least 80%, at least 100%, at least 150%, at least 200%, at least 300%, at least 400%, or at least 500% greater than the average CSF value of the fibrillated fibers of the second layer.
  • Other ranges are also possible.
  • the fibrillated fibers in each of the layers has the same level of fibrillation. Gradients of average levels of fibrillation may also be present across the thickness of the fiber web.
  • the fibrillated fibers may be aligned in the machine direction of the web (i.e., when a fiber's length extends substantially in the machine direction) and/or in the cross-machine direction of the web (i.e., when a fiber's length extends substantially in the cross-machine direction).
  • machine direction refers to the direction in which the fiber web moves along the processing machine during processing
  • cross-machine direction refers to a direction perpendicular to the machine direction.
  • the fiber webs described herein may include cellulose fibers.
  • the cellulose fibers may be fibrillated or non-fibrillated. Mixtures of fibrillated and non-fibrillated cellulose fibers are also possible.
  • the cellulose fibers may include any suitable type of cellulose fibers such as softwood fibers, hardwood fibers, and mixtures thereof.
  • the cellulose fibers may include natural cellulose fibers, synthetic cellulose fibers (e.g., regenerated cellulose), or mixtures thereof.
  • the fiber web may include a suitable percentage of cellulose fibers.
  • the weight percentage of cellulose fibers in the fiber web may be between about 0 wt% and about 100 wt%.
  • the weight percentage of cellulose fibers in the fiber web may be greater than or equal to about 5 wt% , greater than or equal to about 10 wt%, greater than or equal to about 30 wt%, greater than or equal to about 50 wt%, greater than or equal to about 70 wt%, greater than or equal to about 80 wt%, greater than or equal to about 90 wt%, greater than or equal to about 95 wt%, or greater than or equal to about 98 wt%.
  • the weight percentage of the cellulose fibers in the fiber web may be less than or equal to about 100 wt%, less than or equal to about 98 wt%, less than or equal to about 95 wt%, less than or equal to about 90 wt%, less than or equal to about 80 wt , less than or equal to about 70 wt%, less than or equal to about 50 wt%, less than or equal to about 40 wt%, less than or equal to about 20 wt%, less than or equal to about 10 wt%, or less than or equal to about 5 wt%.
  • a fiber web includes 0 wt% of cellulose fibers. In other embodiments, a fiber web includes 100 wt% of cellulose fibers.
  • the weight percentage of cellulose fibers in each of the layers may also vary.
  • the weight percentage of cellulose fibers in the first layer of the fiber web may be between about 0 wt% and about 100 wt%.
  • the weight percentage of cellulose fibers in the first layer of the fiber web may be greater than or equal to about 10 wt%, greater than or equal to about 30 wt%, greater than or equal to about 50 wt%, greater than or equal to about 70 wt%, greater than or equal to about 80 wt%, greater than or equal to about 90 wt%, or greater than or equal to about 95 wt%.
  • the weight percentage of cellulose fibers in the first layer of the fiber web may be less than or equal to about 100 wt%, less than or equal to about 95 wt%, less than or equal to about 90 wt%, less than or equal to about 80 wt , less than or equal to about 70 wt%, less than or equal to about 50 wt%, or less than or equal to about 40 wt , less than or equal to about 20 wt , or less than or equal to about 10 wt%. Combinations of the above-referenced ranges are also possible (e.g., a weight percentage of greater than about 5 wt% and less than or equal to about 80 wt ). Other ranges are also possible.
  • the first layer of the fiber web includes 0 wt of cellulose fibers. In other embodiments, the first layer of the fiber web includes 100 wt% of cellulose fibers.
  • the weight percentage of cellulose fibers in the second layer of the fiber web may be between about 0 wt% and about 100 wt%. In some embodiments, the weight percentage of cellulose fibers in the second layer of the fiber web may be greater than or equal to about 5 wt%, greater than or equal to about 10 wt%, greater than or equal to about 30 wt%, greater than or equal to about 50 wt%, greater than or equal to about 70 wt%, greater than or equal to about 80 wt%, greater than or equal to about 90 wt%, or greater than or equal to about 95 wt%.
  • the weight percentage of cellulose fibers in the second layer of the fiber web may be less than or equal to about 100 wt%, less than or equal to about 95 wt%, less than or equal to about 90 wt%, less than or equal to about 80 wt%, less than or equal to about 70 wt , less than or equal to about 50 wt%, or less than or equal to about 40 wt%, less than or equal to about 20 wt%, or less than or equal to about 10 wt%. Combinations of the above-referenced ranges are also possible (e.g., a weight percentage of greater than about 5 wt and less than or equal to about 80 wt%). Other ranges are also possible.
  • the second layer of the fiber web includes 0 wt% of cellulose fibers. In other embodiments, the second layer of the fiber web includes 100 wt% of cellulose fibers.
  • a fiber web may include any suitable amount of hardwood and/or softwood fibers, which may be fibrillated or non-fibrillated. Mixtures of fibrillated and non- fibrillated hardwood and/or softwood fibers are also possible.
  • the weight percentage of hardwood fibers in the fiber web may be between about 0 wt% and about 98 wt%. In some embodiments, the weight percentage of hardwood fibers in the fiber web may be greater than or equal to about 5 wt% , greater than or equal to about 10 wt%, greater than or equal to about 30 wt%, greater than or equal to about 50 wt%, greater than or equal to about 70 wt%, greater than or equal to about 80 wt%, greater than or equal to about 90 wt%, or greater than or equal to about 98 wt%.
  • the weight percentage of the hardwood fibers in the fiber web may be less than or equal to about 98 wt%, less than or equal to about 90 wt%, less than or equal to about 80 wt%, less than or equal to about 70 wt , less than or equal to about 50 wt%, less than or equal to about 40 wt%, less than or equal to about 20 wt%, less than or equal to about 10 wt%, or less than or equal to about 5 wt . Combinations of the above-referenced ranges are also possible (e.g., a weight percentage of greater than about 5 wt% and less than or equal to about 90 wt%). Other ranges are also possible.
  • a fiber web includes 0 wt% of hardwood fibers.
  • the weight percentage of hardwood fibers in each of the layers may also vary. For example, in some
  • the weight percentage of hardwood fibers in the first layer of the fiber web may be between about 0 wt% and about 100 wt%. In some embodiments, the weight percentage of hardwood fibers in the first layer of the fiber web may be greater than or equal to about 10 wt%, greater than or equal to about 30 wt%, greater than or equal to about 50 wt%, greater than or equal to about 70 wt%, or greater than or equal to about 80 wt%.
  • the weight percentage of hardwood fibers in the first layer of the fiber web may be less than or equal to about 95 wt%, less than or equal to about 90 wt%, less than or equal to about 80 wt%, less than or equal to about 70 wt%, less than or equal to about 50 wt%, or less than or equal to about 40 wt%, less than or equal to about 20 wt%, or less than or equal to about 10 wt%. Combinations of the above- referenced ranges are also possible (e.g., a weight percentage of greater than about 5 wt% and less than or equal to about 80 wt%). Other ranges are also possible.
  • the weight percentage of hardwood fibers in the second layer of the fiber web may be between about 0 wt and about 100 wt%. In some embodiments, the weight percentage of hardwood fibers in the second layer of the fiber web may be greater than or equal to about 5 wt%, greater than or equal to about 10 wt%, greater than or equal to about 30 wt%, greater than or equal to about 50 wt%, greater than or equal to about 70 wt%, or greater than or equal to about 80 wt%.
  • the weight percentage of hardwood fibers in the second layer of the fiber web may be less than or equal to about 95 wt%, less than or equal to about 90 wt%, less than or equal to about 80 wt%, less than or equal to about 70 wt%, less than or equal to about 50 wt%, or less than or equal to about 40 wt%, less than or equal to about 20 wt%, or less than or equal to about 10 wt%. Combinations of the above -referenced ranges are also possible (e.g., a weight percentage of greater than about 5 wt% and less than or equal to about 80 wt%). Other ranges are also possible.
  • the weight percentage of softwood fibers in the fiber web may also vary.
  • the weight percentage of softwood fibers in the fiber web may be between about 0 wt% and about 98 wt%.
  • the weight percentage of softwood fibers in the fiber web may be greater than or equal to about 5 wt% , greater than or equal to about 10 wt%, greater than or equal to about 30 wt%, greater than or equal to about 50 wt%, greater than or equal to about 70 wt%, greater than or equal to about 80 wt%, greater than or equal to about 90 wt%, or greater than or equal to about 98 wt .
  • the weight percentage of the softwood fibers in the fiber web may be less than or equal to about 98 wt%, less than or equal to about 90 wt%, less than or equal to about 80 wt%, less than or equal to about 70 wt%, less than or equal to about 50 wt%, less than or equal to about 40 wt%, less than or equal to about 20 wt , less than or equal to about 10 wt%, or less than or equal to about 5 wt%. Combinations of the above -referenced ranges are also possible (e.g., a weight percentage of greater than about 5 wt% and less than or equal to about 80 wt%). Other ranges are also possible.
  • a fiber web includes 0 wt% of softwood fibers.
  • the weight percentage of softwood fibers in each of the layers may also vary.
  • the weight percentage of softwood fibers in the first layer of the fiber web may be between about 0 wt% and about 100 wt%.
  • the weight percentage of softwood fibers in the first layer of the fiber web may be greater than or equal to about 10 wt%, greater than or equal to about 30 wt , greater than or equal to about 50 wt%, greater than or equal to about 70 wt%, or greater than or equal to about 80 wt%.
  • the weight percentage of softwood fibers in the first layer of the fiber web may be less than or equal to about 95 wt%, less than or equal to about 90 wt , less than or equal to about 80 wt%, less than or equal to about 70 wt%, less than or equal to about 50 wt%, or less than or equal to about 40 wt%, less than or equal to about 20 wt , or less than or equal to about 10 wt%. Combinations of the above-referenced ranges are also possible (e.g., a weight percentage of greater than about 5 wt% and less than or equal to about 80 wt%). Other ranges are also possible.
  • the weight percentage of softwood fibers in the second layer of the fiber web may be between about 0 wt% and about 100 wt%. In some embodiments, the weight percentage of softwood fibers in the second layer of the fiber web may be greater than or equal to about 5 wt , greater than or equal to about 10 wt , greater than or equal to about 30 wt%, greater than or equal to about 50 wt%, greater than or equal to about 70 wt%, or greater than or equal to about 80 wt%.
  • the weight percentage of softwood fibers in the second layer of the fiber web may be less than or equal to about 95 wt%, less than or equal to about 90 wt%, less than or equal to about 80 wt%, less than or equal to about 70 wt%, less than or equal to about 50 wt%, or less than or equal to about 40 wt%, less than or equal to about 20 wt%, or less than or equal to about 10 wt%. Combinations of the above -referenced ranges are also possible (e.g., a weight percentage of greater than about 5 wt% and less than or equal to about 80 wt%). Other ranges are also possible.
  • the fiber webs described herein include one or more synthetic fibers.
  • the synthetic fibers may be fibrillated or non- fibrillated.
  • Synthetic fibers may include any suitable type of synthetic polymer.
  • non-fibrillated synthetic fibers include polyesters (e.g., polyethylene terephthalate, polybutylene terephthalate), polyamide, polyaramid, para- aramid, meta-aramid, polyaniline, polyimide, polyethylene, polypropylene, polyether ether ketone, polyolefin, nylon, acrylics, polyvinyl alcohol, regenerated cellulose (e.g., lyocell, rayon), cellulose acetate, polyvinylidene fluoride, poly(vinylidene fluoride-co- hexafluoropropylene), polyacrylonitriles, polysulfones (e.g., polyether sulfones, poly(phenylene ether sulfone)), polystyrene, polybutadiene, polyurethane, polyphenylene oxide, polycarbonate, poly(methyl methacrylate), polyhydroxyethylmethacrylate, poly(lactic acid) or polylact
  • Synthetic fibers may also include multi-component fibers (i.e., fibers having multiple compositions such as bi-component fibers) including one or more of the polymers described above. For example, islands in the sea fibers may be used.
  • synthetic fibers may include meltblown fibers, which may be formed of fibers described herein (e.g., polyester, polypropylene).
  • synthetic fibers may be electrospun fibers.
  • the synthetic fibers may be centrifugal spun fibers or melt- spun fibers.
  • the fiber web may also include combinations of more than one type of synthetic fiber. It should be understood that other types of synthetic fiber types may also be used.
  • a fiber web may include a suitable percentage of synthetic fibers.
  • the weight percentage of synthetic fibers in the fiber web may be between about 0 wt and about 100 wt .
  • the weight percentage of synthetic fibers in the fiber web may be greater than or equal to about 5 wt% , greater than or equal to about 10 wt%, greater than or equal to about 30 wt%, greater than or equal to about 50 wt , greater than or equal to about 70 wt , greater than or equal to about 80 wt%, greater than or equal to about 90 wt%, or greater than or equal to about 95 wt%.
  • the weight percentage of the synthetic fibers in the fiber web may be less than or equal to about 100 wt , less than or equal to about 95 wt%, less than or equal to about 90 wt%, less than or equal to about 80 wt%, less than or equal to about 70 wt%, less than or equal to about 50 wt%, less than or equal to about 40 wt%, less than or equal to about 20 wt%, or less than or equal to about 10 wt%. Combinations of the above -referenced ranges are also possible (e.g., a weight percentage of greater than about 50 wt% and less than or equal to about 100 wt%). Other ranges are also possible.
  • a fiber web includes 100 wt% of synthetic fibers. In other embodiments, a fiber web includes 0 wt% of synthetic fibers.
  • the fiber web includes one or more inorganic fibers.
  • Inorganic fibers may include, for example, ceramic fibers such as oxides (e.g., alumina, titania, tin oxide, zinc oxide). Mineral fibers can also be included in the fiber web.
  • Inorganic fibers may also include metal fibers such as stainless steel fibers, nickel-coated fibers, and copper-coated fibers.
  • the weight percentage of synthetic fibers in each of the layers may also vary.
  • the weight percentage of synthetic fibers in the first layer of the fiber web may be between about 0 wt% and about 100 wt%.
  • the weight percentage of synthetic fibers in the first layer of the fiber web may be greater than or equal to about 10 wt%, greater than or equal to about 30 wt%, greater than or equal to about 50 wt%, greater than or equal to about 70 wt%, or greater than or equal to about 80 wt%, greater than or equal to about 90 wt%, or greater than or equal to about 95 wt%.
  • the weight percentage of synthetic fibers in the first layer of the fiber web may be less than or equal to about 100 wt%, less than or equal to about 95 wt , less than or equal to about 90 wt%, less than or equal to about 80 wt%, less than or equal to about 70 wt%, less than or equal to about 50 wt%, or less than or equal to about 40 wt%, less than or equal to about 20 wt%, or less than or equal to about 10 wt%. Combinations of the above -referenced ranges are also possible (e.g., a weight percentage of greater than about 50 wt% and less than or equal to about 100 wt%). Other ranges are also possible.
  • the first layer of the fiber web includes 0 wt% of synthetic fibers. In other embodiments, the first layer of the fiber web includes 100 wt of synthetic fibers.
  • the weight percentage of synthetic fibers in the second layer of the fiber web may be between about 0 wt% and about 100 wt%. In some embodiments, the weight percentage of synthetic fibers in the second layer of the fiber web may be greater than or equal to about 10 wt%, greater than or equal to about 30 wt%, greater than or equal to about 50 wt%, greater than or equal to about 70 wt%, or greater than or equal to about 80 wt%, greater than or equal to about 90 wt%, or greater than or equal to about 95 wt%.
  • the weight percentage of synthetic fibers in the second layer of the fiber web may be less than or equal to about 100 wt%, less than or equal to about 95 wt%, less than or equal to about 90 wt%, less than or equal to about 80 wt , less than or equal to about 70 wt%, less than or equal to about 50 wt%, or less than or equal to about 40 wt%, less than or equal to about 20 wt%, or less than or equal to about 10 wt%. Combinations of the above -referenced ranges are also possible (e.g., a weight percentage of greater than about 50 wt% and less than or equal to about 100 wt%). Other ranges are also possible.
  • the second layer of the fiber web includes 100 wt% of synthetic fibers.
  • the fiber webs described herein may also include non-fibrillated synthetic fibers
  • Non- fibrillated synthetic fibers include any suitable type of synthetic polymer including thermoplastic polymers and those polymers described herein for synthetic fibers generally.
  • suitable non-fibrillated synthetic fibers include polyester, polyamide, polyaramid, polyimide, polyethylene, polypropylene, polyether ether ketone, polyethylene terephthalate, polyolefin, nylon, and combinations thereof. It should be understood that other types of non-fibrillated synthetic fiber types may also be used.
  • non-fibrillated synthetic fibers may have any suitable dimensions.
  • non-fibrillated synthetic fibers may have an average diameter of between about 2 microns and about 50 microns, between about 2 microns and about 20 microns, between about 4 microns and about 7 microns, or between about 3 microns and about 7 microns.
  • the non-fibrillated synthetic fibers may have an average diameter of greater than or equal to about 1 micron, greater than or equal to about 2 microns, greater than or equal to about 4 microns, greater than or equal to about 6 microns, greater than or equal to about 8 microns, greater than or equal to about 10 microns, greater than or equal to about 12 microns, greater than or equal to about 15 microns, greater than or equal to about 20 microns, greater than or equal to about 30 microns, or greater than or equal to about 40 microns.
  • the non-fibrillated synthetic fibers may have an average diameter of less than or equal to about 50 microns, less than or equal to about 40 microns, less than or equal to about 30 microns, less than or equal to about 20 microns, less than or equal to about 15 microns, less than or equal to about 12 microns, less than or equal to about 10 microns, than or equal to about 8 microns, less than or equal to about 6 microns, less than equal to about 4 microns, or less than or equal to about 2 microns. Combinations of the above referenced ranges are also possible (e.g., an average diameter of greater than or equal to about 2 microns and less than about 10 microns). Other ranges are also possible.
  • fiber webs having non-fibrillated synthetic fibers with a greater average diameter may exhibit a higher degree of permeability than fiber webs having non-fibrillated synthetic fibers with a comparatively smaller average diameter.
  • the non-fibrillated synthetic fibers described may have an average length of between about 3 mm and about 12 mm, between about 4 mm and about 6 mm, or between about 5 mm and about 7 mm.
  • fiber webs having non-fibrillated synthetic fibers with a greater average length may exhibit a higher degree of tensile strength than fiber webs having non-fibrillated synthetic fibers with a comparatively smaller average length. It should be understood that, in certain embodiments, non-fibrillated synthetic fibers may have dimensions outside the above-noted ranges.
  • non-fibrillated synthetic fibers may be staple fibers, which may be synthetic fibers that are cut or formed as non-continuous discrete fibers to have a suitable average length and are appropriate for incorporation into a wet-laid or non-wet laid (e.g., dry-laid, air laid) process for forming a fiber web.
  • groups of staple fibers may be cut to have a particular length with only slight variations in length between individual fibers.
  • non-fibrillated synthetic fibers may be binder fibers.
  • Non- fibrillated synthetic fibers may be mono -component (i.e., having a single composition, such a polyvinyl alcohol or other polymers described herein) or multi-component (i.e., having multiple compositions such as bi-component fiber). Combinations of different non-fibrillated synthetic fibers are also possible.
  • the fiber web may include a suitable percentage of mono- component fibers and/or multi-component fibers. In some embodiments, all of the non- fibrillated synthetic fibers are mono-component fibers. In some embodiments, at least a portion of the non-fibrillated synthetic fibers are multi-component fibers.
  • An example of a multi-component fiber is a bi-component fiber which includes a first material and a second material that is different from the first material.
  • the different components of a multi-component fiber may exhibit a variety of spatial arrangements.
  • multi-component fibers may be arranged in a core- sheath configuration
  • a first material may be a sheath material that surrounds a second material which is a core material
  • a side by side configuration e.g., a first material may be arranged adjacent to a second material
  • a segmented pie arrangement e.g., different materials may be arranged adjacent to one another in a wedged configuration
  • a tri-lobal arrangement e.g., a tip of a lobe may have a material different from the lobe
  • an arrangement of localized regions of one component in a different component e.g., "islands in sea"
  • a multi-component fiber such as a bi-component fiber, may include a sheath of a first material that surrounds a core comprising a second material.
  • the melting point of the first material may be lower than the melting point of the second material. Accordingly, at a suitable step during manufacture of a fiber web (e.g., drying), the first material comprising the sheath may be melted (e.g., may exhibit a phase change) while the second material comprising the core remains unaltered (e.g., may exhibit no phase change).
  • an outer sheath portion of a multi-component fiber may have a melting temperature between about 50 °C and about 200 °C (e.g., 180 °C) and an inner core of the multi-component fiber may have a melting temperature above 200 °C.
  • a temperature during drying e.g., at 180 °C
  • the outer sheath of the fiber may melt while the core of the fiber does not melt.
  • a fiber web may include a suitable percentage of non-fibrillated synthetic fibers.
  • the weight percentage of non-fibrillated synthetic fibers in the fiber web may be between about 0 wt% and about 98 wt%. In some embodiments, the weight percentage of non-fibrillated synthetic fibers in the fiber web may be greater than or equal to about 5 wt% , greater than or equal to about 10 wt%, greater than or equal to about 30 wt%, greater than or equal to about 50 wt%, greater than or equal to about 70 wt%, or greater than or equal to about 80 wt%.
  • the weight percentage of the non-fibrillated synthetic fibers in the fiber web may be less than or equal to about 95 wt%, less than or equal to about 90 wt%, less than or equal to about 80 wt%, less than or equal to about 70 wt%, less than or equal to about 50 wt%, less than or equal to about 40 wt%, less than or equal to about 20 wt%, or less than or equal to about 10 wt%. Combinations of the above-referenced ranges are also possible (e.g., a weight percentage of greater than about 5 wt% and less than or equal to about 80 wt%). Other ranges are also possible.
  • a fiber web includes 0 wt% of non-fibrillated synthetic fibers.
  • the weight percentage of non- fibrillated synthetic fibers (e.g., staple fibers) in each of the layers may also vary.
  • the weight percentage of non-fibrillated synthetic fibers in the first layer of the fiber web may be between about 0 wt% and about 100 wt%.
  • the weight percentage of non-fibrillated synthetic fibers in the first layer of the fiber web may be greater than or equal to about 10 wt%, greater than or equal to about 30 wt%, greater than or equal to about 50 wt%, greater than or equal to about 70 wt , or greater than or equal to about 80 wt%.
  • the weight percentage of non-fibrillated synthetic fibers in the first layer of the fiber web may be less than or equal to about 95 wt%, less than or equal to about 90 wt%, less than or equal to about 80 wt%, less than or equal to about 70 wt%, less than or equal to about 50 wt%, or less than or equal to about 40 wt%, less than or equal to about 20 wt%, or less than or equal to about 10 wt%. Combinations of the above-referenced ranges are also possible (e.g., a weight percentage of greater than about 5 wt% and less than or equal to about 80 wt ). Other ranges are also possible.
  • the first layer of the fiber web includes 0 wt% of non-fibrillated synthetic fibers. In other embodiments, the first layer of the fiber web includes 100 wt of non-fibrillated synthetic fibers.
  • the weight percentage of non-fibrillated synthetic fibers in the second layer of the fiber web may be between about 0 wt% and about 98 wt%. In some embodiments, the weight percentage of non-fibrillated synthetic fibers in the second layer of the fiber web may be greater than or equal to about 10 wt%, greater than or equal to about 30 wt%, greater than or equal to about 50 wt%, greater than or equal to about 70 wt%, or greater than or equal to about 80 wt .
  • the weight percentage of non-fibrillated synthetic fibers in the second layer of the fiber web may be less than or equal to about 95 wt , less than or equal to about 90 wt%, less than or equal to about 80 wt%, less than or equal to about 70 wt%, less than or equal to about 50 wt%, or less than or equal to about 40 wt%, less than or equal to about 20 wt%, or less than or equal to about 10 wt%. Combinations of the above-referenced ranges are also possible (e.g., a weight percentage of greater than about 5 wt% and less than or equal to about 80 wt%). Other ranges are also possible.
  • the second layer of the fiber web includes 0 wt% of non-fibrillated synthetic fibers.
  • the fiber web may include multiple types of non- fibrillated synthetic fibers.
  • the fiber web may include limited amounts of, if any, glass fibers.
  • the weight percentage of glass fiber in the fiber web may be between about 0 wt% and about 20 wt% (e.g., between about 0 wt% and about 10 wt%, between 0 wt% and about 5 wt , between 0 wt% and about 2 wt%, or between 0 wt and about 1 wt ).
  • the weight percentage of glass fibers in the fiber web may be less than or equal to about 20 wt%, less than or equal to about 15 wt%, less than or equal to about 10 wt%, less than or equal to about 8 wt , less than or equal to about 6 wt%, less than or equal to about 5 wt%, less than or equal to about 4 wt%, less than or equal to about 2 wt%, or less than or equal to about 1 wt%. Other ranges are also possible. When the fiber web includes less than 1 wt% of glass fiber, it is considered that the fiber web is substantially free of glass fiber.
  • the weight percentage of glass fibers in each of the layers may also vary.
  • the weight percentage of glass fibers in the first layer of the fiber web may be between about 0 wt% and about 20 wt% (e.g., between about 0 wt to about 10 wt%, between 0 wt% to about 5 wt%, between 0 wt% to about 2 wt%, or between 0 wt to about 1 wt%).
  • the weight percentage of glass fibers in the first layer of the fiber web may be less than or equal to about 20 wt%, less than or equal to about 15 wt%, less than or equal to about 10 wt%, less than or equal to about 8 wt%, less than or equal to about 6 wt%, less than or equal to about 5 wt%, less than or equal to about 4 wt%, less than or equal to about 2 wt%, or less than or equal to about 1 wt%.
  • the first layer includes 0 wt% of glass fibers. Other ranges are also possible.
  • the weight percentage of glass fibers in the second layer of the fiber web may be between about 0 wt% and about 20 wt% (e.g., between about 0 wt% to about 10 wt%, between 0 wt% to about 5 wt%, between 0 wt% to about 2 wt%, or between 0 wt% to about 1 wt%).
  • the weight percentage of glass fibers in the second layer of the fiber web may be less than or equal to about 20 wt%, less than or equal to about 15 wt%, less than or equal to about 10 wt%, less than or equal to about 8 wt%, less than or equal to about 6 wt%, less than or equal to about 5 wt%, less than or equal to about 4 wt%, less than or equal to about 2 wt%, or less than or equal to about 1 wt%.
  • the second layer includes 0 wt% of glass fibers. Other ranges are also possible.
  • a fiber web having limited amounts of, if any, glass fibers when used with various machine or engine parts may result in a marked decrease in abrasion and wear as compared to a fiber web having substantially more glass fibers incorporated therein.
  • Limited amounts or absence of glass fibers may also reduce the amount of fiber shedding from the fiber media during installation or use. Accordingly, using fiber webs that include little to no glass fibers therein may alleviate the necessity of having a protective scrim that may be otherwise be installed downstream from the filter media.
  • a fiber web may include an additional layer (e.g., a third layer, a fourth layer, ... a tenth layer, etc.).
  • the additional layer may be positioned upstream or downstream of the first layer, or upstream or downstream of the second layer.
  • an additional layer may be positioned between a first layer and a second layer.
  • more than one additional layers e.g., up to 10 layers, which may be the same or different from one another, may be included in a fiber web at various positions with respect to the first or second layers.
  • the additional layer may have a basis weight of between about 5 g/m 2 and about 800 g/m 2 , an air
  • the additional layer may be used to enhance one or more of dust holding capacity, lifetime, liquid filtration efficiency, water separation efficiency, and/or strength (e.g., Mullen burst strength, tensile strength, elongation) of the fiber web, although other uses for the additional layer are possible.
  • an additional layer that may be used to enhance dust holding capacity of the fiber web may have, for example, a basis weight of less than or equal to 300 g/m 2 , an air permeability of less than or equal to 700 cfm/sf, and an average fiber diameter of less than or equal to 20 microns, although other ranges are also possible.
  • an additional layer that may be used to enhance efficiency of the fiber web may have, for example, a basis weight of less than or equal to 100 g/m 2 , an air permeability of less than or equal to 700 cfm/sf, and an average fiber diameter of less than or equal to 4 microns, although other ranges are also possible.
  • an additional layer that may be used to enhance water separation efficiency (e.g., fuel- water separation efficiency) of the fiber web may have, for example, a basis weight of less than or equal to 800 g/m 2 , an air permeability of less than or equal to 1300 cfm/sf, and an average fiber diameter of less than or equal to 50 microns, although other ranges are also possible.
  • the additional layer may be formed of any suitable fibers and the layer may be non-woven or woven.
  • the additional layer is non-wet laid and includes non-wet laid fibers, e.g., meltblown fibers, meltspun fibers, dry laid (carded) fibers, centrifugal spun fibers, spunbond fibers, and/or air laid fibers.
  • the additional layer includes continuous fibers.
  • the additional layer includes staple fibers (e.g., fibers having a length of between about 1 mm and about 55 mm).
  • the additional layer does not include any fibrillated fibers, although fibrillated fibers may be included in other embodiments.
  • the materials used to form the fibers of the additional layer may include the ones described herein (e.g., synthetic, organic, and/or inorganic materials).
  • An additional layer may be in the form of a mesh in some cases.
  • the mesh may be formed of any suitable materials such as the ones described herein (e.g., synthetic, organic, and/or inorganic materials). Additionally, metals such as stainless steel may be used.
  • the mesh may have an suitable average opening size, such as between about 0.001 mm and about 7 mm (e.g., at least about 0.001 mm, at least about 0.01 mm, at least about 0.1 mm, at least about 1 mm, at least about 3 mm, or at least about 5 mm and/or less than or equal to about 7 mm, less than or equal to about 4 mm, less than or equal to about 2 mm, less than or equal to about 1 mm). Other ranges are also possible.
  • the fibers of an additional layer may have any suitable dimensions.
  • fibers of an additional layer may have an average diameter of between about 100 nm and about 100 microns (e.g., between about 100 nm and about 50 microns, between about 100 nm and about 4 microns, between about 1 micron and about 20 microns, or between about 1 micron and about 50 microns).
  • the additional layer may have an average diameter of greater than or equal to about 100 nm, greater than or equal to about 1 micron, greater than or equal to about 2 microns, greater than or equal to about 4 microns, greater than or equal to about 10 microns, greater than or equal to about 15 microns, greater than or equal to about 20 microns, greater than or equal to about 30 microns, or greater than or equal to about 40 microns.
  • the fibers of an additional layer may have an average diameter of less than or equal to about 50 microns, less than or equal to about 40 microns, less than or equal to about 30 microns, less than or equal to about 20 microns, less than or equal to about 15 microns, less than or equal to about 10 microns, less than or equal to about 8 microns, less than or equal to about 6 microns, less than equal to about 4 microns, or less than or equal to about 2 microns, or less than or equal to about 1 micron. Combinations of the above referenced ranges are also possible. Other ranges are also possible.
  • the length of the fibers in an additional layer may vary between about 1 mm and about 20 cm (e.g., at least about 1 mm, at least about 5 mm, at least about 10 mm, at least about 50 mm, at least about 1 cm, at least about 5 cm, at least about 10 cm and/or less than or equal to about 20 cm, less than or equal to about 15 cm, less than or equal to about 10 cm, less than or equal to about 5 cm, less than or equal to about 1 cm, less than or equal to about 50 mm, less than or equal to about 20 mm, or less than or equal to about 10 mm). Other ranges are also possible. Continuous fibers may also be included.
  • a filter media includes a first layer and/or a second layer in combination with an additional layer described herein.
  • the first layer and/or second layer may be a wet laid layer (e.g., a layer formed by a wet laid process).
  • the additional layer may be a non-wet laid layer (e.g., it may include meltblown fibers, meltspun fibers, centrifugal spun fibers, electrospun fibers, or fibers formed by other non-wet laid processes).
  • the first and/or second layer includes a plurality of synthetic fibers and/or organic polymer fibers.
  • a filter media includes a first layer that comprises a plurality of organic polymer fibers, and a second layer that comprises a plurality of synthetic fibers.
  • at least one of the first and/or second layers includes fibrillated fibers in an amount described herein (e.g., between about 1 wt% and about 100 wt% of the first and/or second layers).
  • the first and/or second layers may comprise between about 0 wt% to about 10 wt% of glass fibers (e.g., the first and/or second layers may be substantially free of glass fibers).
  • the first and/or second layers may be configured, in some embodiments, to have one or more of the following: a [mean flow pore
  • the additional layer which may be used to enhance one or more of dust holding capacity, lifetime, liquid filtration efficiency, water separation efficiency, and/or strength (e.g., Mullen burst strength, tensile strength, elongation) of the fiber web, may include synthetic polymer fibers.
  • the additional layer may have, for example, a basis weight of between about 5 g/m 2 and about 800 g/m 2 , an air permeability of less than about 100 cfm/sf, and an average fiber diameter of less than 100 microns.
  • the overall filter media may have an basis weight of greater than about 10 g/m 2 and less than or equal to about 1000 g/m 2 , a thickness of between about 0.1 mm and about 10.0 mm.
  • the filter media can achieve an efficiency at 4 microns of at least 99%, an initial efficiency of at least 99%, and a dust holding capacity of at least 150 gsm.
  • the filter media can achieve a fuel-water separation efficiency of at least about 30% (e.g., between about 60% to about 99.9%, between about 80% to about 99.9%, or between about 90% to about 99.9%).
  • the fiber web may include a binder resin.
  • the binder resin is not in fiber form and is to be distinguished from binder fiber (e.g., multi-component fiber) described above.
  • the binder resin may have any suitable composition.
  • the binder resin may comprise a thermoplastic (e.g., acrylic,
  • a binder resin includes one or more of a vinyl acetate resin, an epoxy resin, a polyester resin, a copolyester resin, a polyvinyl alcohol resin, an acrylic resin such as a styrene acrylic resin, and a phenolic resin. Other resins are also possible.
  • the amount of binder resin in a fiber web may vary.
  • the weight percentage of binder resin in the fiber web may be between 0 wt% and 45 wt%.
  • the weight percentage of binder resin in the fiber web may be greater than or equal to about 2 wt%, greater than or equal to about 5 wt%, greater than or equal to about 10 wt%, greater than or equal to about 15 wt%, greater than or equal to about 20 wt%, greater than or equal to about 25 wt%, greater than or equal to about 30 wt%, greater than or equal to about 35 wt%, or greater than or equal to about 40 wt%
  • the weight percentage of binder resin in the fiber web may be less than or equal to about 45 wt%, less than or equal to about 40 wt%, less than or equal to about 35 wt%, less than or equal to about 30 wt%, less than or equal to about 25 wt%, less than or equal to about 20
  • the binder resin may be added to the fibers in any suitable manner including, for example, in the wet fiber web state.
  • the binder coats the fibers and is used to adhere fibers to each other to facilitate adhesion between the fibers. Any suitable method and equipment may be used to coat the fibers, for example, using curtain coating, gravure coating, melt coating, dip coating, knife roll coating, or spin coating, amongst others.
  • the binder is precipitated when added to the fiber blend.
  • any suitable precipitating agent e.g., Epichlorhydrin, fluorocarbon
  • the binder resin upon addition to the fiber blend, the binder resin is added in a manner such that the fiber web is impregnated with the binder resin (e.g., the binder resin permeates throughout the fiber web).
  • a binder resin may be added to one side or both sides of a layer or web after the layer or web has been dried (e.g., after being formed using a wet laid process).
  • a binder resin may be added to one or more, or each of the layers separately prior to combining the layers, or the binder resin may be added to the fiber web after combining the layers.
  • binder resin is added to the first and/or second layers, for example, by spraying or saturation impregnation (e.g., a solvent saturation process), or any of the above methods.
  • a binder resin or binder mixture may be added to the first and/or second layers of a fiber web by a solvent saturation process.
  • a polymeric material can be impregnated into the first and/or second layers either during or after the layers are being manufactured on a papermaking machine. For example, during a manufacturing process described herein, after the article containing first layer and second layer is formed and dried, a polymeric material in a water based emulsion or an organic solvent based solution can be adhered to an application roll and then applied to the article under a controlled pressure by using a size press or gravure saturator. The amount of the polymeric material impregnated into the article typically depends on the viscosity, solids content, and absorption rate of article.
  • a fiber web after a fiber web is formed, it can be impregnated with a polymeric material by using a reverse roll applicator following the just-mentioned method and/or by using a dip and squeeze method (e.g., by dipping a dried filter media into a polymer emulsion or solution and then squeezing out the excess polymer by using a nip).
  • a polymeric material can also be applied to a fiber web by other methods known in the art, such as spraying or foaming.
  • the fiber web may, or may not, include other components in addition to those described above. Typically, any additional components, are present in limited amounts, e.g., less than 5 % by weight.
  • the fiber web may include wet and dry strength additives or resins that include natural polymers (starches, gums), cellulose derivatives, such as carboxymefhyl cellulose, methylcellulose, hemicelluloses, synthetic polymers such as phenolics, latexes, polyamides, polyacrylamides, urea-formaldehyde, melamine-formaldehyde,
  • polyamides polyamides
  • surfactants coupling agents, crosslinking agents, and/or conductive additives, amongst others.
  • Fiber webs described herein may be used in an overall filtration arrangement or filter element.
  • a fiber web includes at least a first layer and a second layer, with at least one of the layers including a fibrillated fiber.
  • one or more additional layers or components are included with the fiber web (e.g., disposed adjacent to the fiber web, contacting one or both sides of the fiber web).
  • the one or more additional layers may be formed predominantly of or entirely of non-fibrillated fibers, although in other embodiments, fibrillated fibers may be included.
  • additional layers include a meltblown layer, a wet laid layer, a coarse fiber electret media, a spunbond layer, or an electrospun layer.
  • multiple fiber webs comprising predominantly fibrillated fibers and non-fibrillated fibers in accordance with embodiments described herein may be layered together in forming a multi-layer sheet for use in a filter media or element.
  • two or more layers of a web may be formed separately, and combined by any suitable method such as lamination, collation, or by use of adhesives.
  • the two or more layers may be formed using different processes, or the same process.
  • each of the layers may be independently formed by a wet laid process, a non-wet laid process (e.g., a dry laid process, a spinning process, a meltblown process), or any other suitable process.
  • the wet laid layers or non-wet laid layers can be formed on a scrim or other suitable substrate directly.
  • two or more layers may be formed by the same process
  • the two or more layers may be formed simultaneously.
  • a gradient in at least one property may be present across the thickness of the two or more layers.
  • the meltblown layer may have one or more characteristics described in commonly-owned U.S. Patent Publication No. 2009/0120048, entitled “Meltblown Filter Medium", which is based on U.S. Patent Application Serial No. 12/266,892, filed on May 14, 2009, and commonly- owned U.S. Apl. No. 12/971,539, entitled “Fine Fiber Filter Media and Processes", filed on December 17, 2010, each of which is incorporated herein by reference in its entirety for all purposes.
  • layers may be adhered together by any suitable method. For instance, layers may be adhered by an adhesive and/or melt-bonded to one another on either side. Lamination and calendering processes may also be used. In some embodiments, an additional layer may be formed from any type of fiber or blend of fibers via an added headbox or a coater and appropriately adhered to another layer.
  • the fiber webs may have a variety of desirable properties and characteristics which are described in the following paragraphs.
  • the basis weight of the fiber web can vary depending on factors such as the strength requirements of a given filtering application, the materials used to form the filter media, as well as the desired level of filter efficiency and permissible levels of resistance or pressure drop.
  • some fiber webs may have a low basis weight while achieving advantageous filtration performance or mechanical characteristics.
  • a fiber web incorporating fibrillated fibers which provides for an enhanced surface area of the fiber web may have a lower basis weight without sacrificing strength.
  • the basis weight of the fiber web can typically be selected as desired.
  • the basis weight of the fiber web may range from between about 5 and about 1000 g/m 2 .
  • the basis weight of the fiber web may be between about 15 and about 400 g/m 2 , between about 30 and about 300 g/m 2 , between about 50 and about 200 g/m 2 , between about 90 g/m 2 and about 200 g/m 2 , between about 90 g/m 2 and about 150 g/m 2 .
  • the basis weight of the fiber web may be greater than or equal to about 5 g/m 2 (e.g., greater than or equal to about 10 g/m 2 , greater than or equal to about 40 g/m 2 , greater than or equal to about 75 g/m 2 , greater than or equal to about 100 g/m 2 , greater than or equal to about 150 g/m 2 , greater than or equal to about 200 g/m 2 , greater than or equal to about 250 g/m 2 , greater than or equal to about 300 g/m 2 , greater than or equal to about 350 g/m 2 , or greater than or equal to about 400 g/m 2 ).
  • the basis weight of the fiber web may be less than or equal to about 1000 g/m 2 (e.g., less than or equal to about 700 g/m 2 , less than or equal to about 500 g/m 2 , less than or equal to about 400 g/m 2 , less than or equal to about 350 g/m 2 , less than or equal to about 300 g/m 2 , less than or equal to about 250 g/m 2 , less than or equal to about 200 g/m 2 , less than or equal to about 150 g/m 2 , less than or equal to about 100 g/m 2 , less than or equal to about 75 g/m 2 , or less than or equal to about 50 g/m 2 ).
  • a fiber web includes at least first and second layers, as shown illustratively in FIG. 1.
  • the first layer may have a basis weight that ranges between about 5 and about 1000 g/m 2 .
  • the basis weight of the first layer may be greater than or equal to about 8 g/m 2 (e.g., greater than or equal to about 10 g/m 2 , greater than or equal to about 40 g/m 2 , greater than or equal to about 65 g/m 2 , greater than or equal to about 75 g/m 2 , greater than or equal to about 100 g/m 2 , greater than or equal to about 150 g/m 2 , greater than or equal to about 200 g/m 2 , greater than or equal to about 250 g/m 2 , greater than or equal to about 300 g/m 2 , greater than or equal to about 350 g/m 2 , greater than or equal to about 400 g/m 2 , greater than or equal to about 500
  • the basis weight of the first layer is less than or equal to about 1000 g/m 2 (e.g., less than or equal to about 1000 g/m 2 , less than or equal to about 900 g/m 2 , less than or equal to about 800 g/m 2 , less than or equal to about 700 g/m 2 , less than or equal to about 600 g/m 2 , less than or equal to about 500 g/m 2 , less than or equal to about 400 g/m 2 , less than or equal to about 350 g/m 2 , less than or equal to about 300 g/m 2 , less than or equal to about 250 g/m 2 , less than or equal to about 200 g/m 2 , less than or equal to about 165 g/m 2 , less than or equal to about 150 g/m 2 , less than or equal to about 100 g/m 2 , less than or equal to about 75 g/m 2 , less than or equal to about 50 g/m 2
  • the second layer may have a basis weight that ranges between about 3 and about 1000 g/m 2 .
  • the basis weight of the second layer may be greater than or equal to about 3 g/m 2 (e.g., greater than or equal to about 8 g/m 2 , greater than or equal to about 10 g/m 2 , greater than or equal to about 15 g/m 2 , greater than or equal to about 20 g/m 2 , greater than or equal to about 30 g/m 2 , greater than or equal to about 40 g/m 2 , greater than or equal to about 45 g/m 2 , greater than or equal to about 50 g/m 2 , greater than or equal to about 75 g/m 2 , greater than or equal to about 100 g/m 2 , greater than or equal to about 150 g/m 2 , greater than or equal to about 200 g/m 2 , greater than or equal to about 250 g/m 2 , greater than or equal to about 300 g/m 2 , greater than or equal
  • the basis weight of the second layer is less than or equal to about 1000 g/m 2 , less than or equal to about 900 g/m 2 , less than or equal to about 800 g/m 2 , less than or equal to about 700 g/m 2 , less than or equal to about 600 g/m 2 , less than or equal to about 500 g/m 2 , less than or equal to about 400 g/m 2 , less than or equal to about 350 g/m 2 , less than or equal to about 300 g/m 2 , less than or equal to about 250 g/m 2 , less than or equal to about 200 g/m 2 , less than or equal to about 165 g/m 2 , less than or equal to about 150 g/m 2 , less than or equal to about 100 g/m 2 , less than or equal to about 75 g/m 2 (e.g., less than or equal to about 50 g/m 2 , less than or equal to about 45 g/m 2
  • the basis weights of the first and second layers may be chosen to achieve a particular basis weight ratio.
  • the basis weight ratio between the first and second layers e.g., basis weight of first layer: basis weight of second layer
  • the basis weight ratio between the first and second layers may be at least 1:1, at least 2:1, at least 3: 1, at least 5: 1, at least 6: 1, at least 10:1, at least 15:1, or at least 20:1.
  • the basis weight ratio between the first and second layers is less than 20:1, less than 15:1, less than 14:1, less than 10:1, less than 6:1, less than 5: 1, less than 4: 1, less than 3:1, less than 2:1.
  • Combinations of the above-referenced ranges are also possible (e.g., a basis weight ratio of at least 3: 1 and less than 5:1). Other ranges are also possible.
  • the basis weight ratio between the second and first layers may be at least 1: 1, at least 2: 1, at least 3: 1, at least 5: 1, at least 6: 1, at least 10:1, at least 15: 1, or at least 20: 1.
  • the basis weight ratio between the first and second layers is less than 20:1, less than 15:1, less than 14:1, less than 10:1, less than 6: 1, less than 5: 1, less than 4: 1, less than 3: 1, less than 2:1. Combinations of the above-referenced ranges are also possible (e.g., a basis weight ratio of at least 3: 1 and less than 5:1).
  • the additional layer may have a basis weight that ranges between about 5 and about 800 g/m 2 .
  • the basis weight of the additional layer may be greater than or equal to about 5 g/m 2 (e.g., greater than or equal to about 10 g/m 2 , greater than or equal to about 40 g/m 2 , greater than or equal to about 65 g/m 2 , greater than or equal to about 75 g/m 2 , greater than or equal to about 100 g/m 2 , greater than or equal to about 150 g/m 2 , greater than or equal to about 200 g/m 2 , greater than or equal to about 250 g/m 2 , greater than or equal to about 300 g/m 2 , greater than or equal to about 400 g/m 2 , greater than or equal to about 500 g/m 2 , greater than or equal to about 600 g/m
  • the basis weight of the additional layer is less than or equal to about 800 g/m 2 (e.g., less than or equal to about 700 g/m 2 , less than or equal to about 600 g/m 2 , less than or equal to about 500 g/m 2 , less than or equal to about 400 g/m 2 , less than or equal to about 300 g/m 2 , less than or equal to about 250 g/m 2 , less than or equal to about 200 g/m 2 , less than or equal to about 165 g/m 2 , less than or equal to about 150 g/m 2 , less than or equal to about 100 g/m 2 , less than or equal to about 75 g/m 2 , less than or equal to about 50 g/m 2 ).
  • 800 g/m 2 e.g., less than or equal to about 700 g/m 2 , less than or equal to about 600 g/m 2 , less than or equal to about 500 g/m 2 , less than or
  • the fiber webs described herein may have a relatively high surface area.
  • a fiber web may have a surface area between about 0.1 m 2 /g and about 100 m 2 /g.
  • a fiber web has a surface area of about 0.1 m 2 /g or greater, about 1 m 2 /g or greater, about 1.5 m 2 /g or greater, about 2.0 m 2 /g or greater, about 2.5 m 2 /g or greater, about 3 m 2 /g or greater, about 5 m 2 /g or greater, about 10 m 2 /g or greater, about 20 m 2 /g or greater, about 30 m 2 /g or greater, about 40 m 2 /g or greater, about 50 m 2 /g or greater, about 60 m 2 /g or greater, about 70 m 2 /g or greater, about 80 m 2 /g or greater, or about 90 m 2 /g or greater.
  • a fiber web has a surface area of about 100 m 2 /g or less, about 90 m 2 /g or less, about 80 m 2 /g or less, about 70 m 2 /g or less, about 60 m 2 /g or less, about 50 m 2 /g or less, about 40 m 2 /g or less, about 30 m 2 /g or less, about 20 m 2 /g or less, about 10 m 2 /g or less, about 5 m 2 /g or less, or about 2 m 2 /g or less. Combinations of the above-referenced ranges are also possible (e.g., a surface area of between about 100 m 2 /g or less and about 10 m 2 /g or greater). Other ranges are also possible.
  • a layer e.g., a first layer and/or a second layer
  • surface area is measured through use of a standard BET surface area measurement technique.
  • the BET surface area is measured according to section 10 of Battery Council International Standard BCIS-03A, "Recommended Battery Materials Specifications Valve Regulated Recombinant Batteries", section 10 being "Standard Test Method for Surface Area of Recombinant Battery Separator Mat”.
  • the BET surface area is measured via adsorption analysis using a BET surface analyzer (e.g., Micromeritics Gemini ⁇ 2375 Surface Area Analyzer) with nitrogen gas; the sample amount is between 0.5 and 0.6 grams in a 3/4" tube; and, the sample is allowed to degas at 75 degrees C for a minimum of 3 hours.
  • a BET surface analyzer e.g., Micromeritics Gemini ⁇ 2375 Surface Area Analyzer
  • Thickness is determined according to the Standard TAPPI T411.
  • the thickness of the fiber web may be between about 0.3 mm and about 10 mm. In some embodiments, the thickness of the fiber web may be greater than or equal to about 0.3 mm, greater than or equal to about 0.5 mm, greater than or equal to about 0.6 mm, greater than or equal to about 0.8 mm, greater than or equal to about 1.0 mm, greater than or equal to about 1.2 mm, greater than or equal to about 1.5 mm, greater than or equal to about 2 mm, greater than or equal to about 3 mm, greater than or equal to about 4 mm, greater than or equal to about 5 mm, or greater than or equal to about 7 mm.
  • the thickness of the fiber web may be less than or equal to about 10 mm, less than or equal to about 7 mm, less than or equal to about 5 mm, less than or equal to about 4 mm, less than or equal to about 2 mm, less than or equal to about 1.2 mm, less than or equal to about 1.0 mm, less than or equal to about 0.8 mm, less than or equal to about 0.6 mm, or less than or equal to about 0.4 mm, less than or equal to about 0.2 mm. Combinations of the above-referenced ranges are also possible (e.g., a thickness of greater than about 0.3 mm and less than or equal to about 1.0 mm). Other ranges are also possible.
  • a layer e.g., a first layer and/or a second layer
  • the fiber web may exhibit a suitable mean flow pore size.
  • Mean flow pore size as determined herein, is measured according to Standard ASTM F316.
  • the mean flow pore size may range between about 0.1 microns and about 50 microns (e.g., between about 0.1 microns and about 5 microns, between about 5 microns and about 40 microns, between about 15 microns and about 40 microns, or between about 25 microns and about 40 microns).
  • the mean flow pore size of the fiber web may be less than or equal to about 50 microns, less than or equal to about 45 microns, less than or equal to about 40 microns, less than or equal to about 30 microns, less than or equal to about 25 microns, less than or equal to about 20 microns, less than or equal to about 15 microns, less than or equal to about 10 microns, or less than or equal to about 5 microns, less than or equal to about 3 microns, less than or equal to about 2 microns, less than or equal to about 1 micron, less than or equal to about 0.8 microns, less than or equal to about 0.5 microns, or less than or equal to about 0.2 microns.
  • the mean flow pore size may be greater than or equal to about 0.1 microns, greater than or equal to about 0.2 microns, greater than or equal to about 0.5 microns, greater than or equal to about 0.8 microns, greater than or equal to about 1 micron, greater than or equal to about 2 microns, greater than or equal to about 5 microns, greater than or equal to about 10 microns, greater than or equal to about 15 microns, greater than or equal to about 20 microns, greater than or equal to about 25 microns, greater than or equal to about 30 microns, greater than or equal to about 35 microns, greater than or equal to about 45 microns or greater than or equal to about 50 microns.
  • the fiber web may exhibit certain mechanical properties.
  • a fiber web comprised primarily of fibrillated synthetic fibers and non-fibrillated synthetic fibers e.g., a fiber web having limited amounts of, or no, glass fiber
  • fiber webs described herein that have little to no glass fibers may exhibit a greater degree of elongation, burst strength and/or tensile strength relative to fiber webs having comparatively more glass fibers incorporated therein.
  • the tensile elongation in the machine direction of the fiber web may be greater than about 0.2%, greater than about 0.5%, greater than about 0.8%, greater than about 2%, greater than about 5%, greater than about 8%, greater than about 10%, and/or less than or equal to about 12%.
  • the tensile elongation in the machine direction of the fiber web may be between about 0.2% and about 4.0%, between about 0.2% and about 3.0%, between about 0.5% and about 3.5%, between about 0.5% and about 2.0%, between about 1.0% and about 3.0%, between about 1.5% and about 2.5%, or between about 0.2% and about 12%.
  • the tensile elongation in the cross-machine direction of the fiber web may be greater than about 0.2%, greater than about 0.5%, greater than about 0.8%, or greater than about 1.0%, greater than about 2%, greater than about 5%, greater than about 8%, greater than about 10%, and/or less than or equal to about 12%.
  • the tensile elongation in the cross-machine direction of the fiber web may be between about 0.2% and about 6.0%, between about 0.2% and about 5.0%, between about 0.2% and about 4.0%, between about 0.5% and about 4.5%, between about 1.0% and about 3.5%, between about 1.0% and about 3.0%, between about 2.0% and about 3.5%, or between about 0.2% and about 12%.
  • fiber webs that exhibit an increased degree of elongation may also be more pleatable, for example, by exhibiting an overall reduction in potential damage that may arise at the edges of the filter media.
  • the tensile strength in the machine direction of the filter media may be greater than about 2 N/15mm, greater than about 4 N/15mm, greater than about 6 N/15mm, greater than about 10 N/15mm, greater than about 20 N/15mm, greater than about 50 N/15mm, greater than about 75 N/15mm, greater than about 100 N/15mm, greater than about 125 N/15mm, greater than about 150 N/15mm, or greater than about 175 N/15mm, and/or less than or equal to about 200 N/15mm.
  • the tensile strength in the machine direction of the fiber web may be between about 3 N/15mm and about 20 N/15mm, between about 1 N/15mm and about 6 N/15mm, between about 10 N/15mm and about 20 N/15mm, between about 1 N/15mm and about 200 N/15mm, or between about 100 N/15mm and about 200 N/15mm.
  • the tensile strength of the fiber web in the cross-machine direction may be greater than about 1 N/15mm, greater than about 3 N/15mm, greater than about 4 N/15mm, greater than about 6 N/15mm, greater than about 10 N/15mm, greater than about 20 N/15mm, greater than about 50 N/15mm, greater than about 75 N/15mm, greater than about 100 N/15mm, greater than about 125 N/15mm, greater than about 150 N/15mm, or greater than about 175 N/15mm, and/or less than or equal to about 200 N/15mm.
  • the tensile strength of the fiber web in the cross-machine direction may be between about 1 N/15mm and about 6 N/15mm, between about 2 N/15mm and about 10 N/15mm, or between about 3 N/15mm and about 9 N/15mm, between about 1 N/15mm and about 200 N/15mm, or between about 100 N/15mm and about 200 N/15mm.
  • the cross machine direction tensile strength may be greater or less than the machine direction tensile strength.
  • the Mullen burst strength for the fiber web may be greater than 10 psi, greater than 15 psi, greater than 30 psi, greater than 40 psi, greater than 60 psi, greater than 75 psi, or between about 5 psi and about 120 psi, between about 5 psi and about 50 psi, or between about 30 psi and about 100 psi.
  • the fiber web described herein may also exhibit advantageous filtration performance characteristics, such as dust holding capacity (DHC), efficiency, air permeability, amongst others.
  • DHC dust holding capacity
  • efficiency efficiency
  • air permeability amongst others.
  • the fiber web may have a DHC of between about 80 g/m 2 and about 300 g/m 2 .
  • the DHC may be greater than or equal to about 80 g/m 2 , greater than or equal to about 100 g/m 2 , greater than or equal to about 125 g/m 2 , greater than or equal to about 150 g/m 2 , greater than or equal to about 175 g/m 2 , greater than or equal to about 200 g/m 2 , greater than or equal to about 225 g/m 2 , greater than or equal to about 250 g/m 2 , greater than or equal to about 275 g/m 2 , greater than or equal to about 300 g/m 2 , or greater than or equal to about 350 g/m 2 .
  • the DHC may be less than or equal to about 400 g/m 2 , less than or equal to about 350 g/m 2 , less than or equal to about 300 g/m 2 , less than or equal to about 275 g/m 2 , less than or equal to about 250 g/m 2 , less than or equal to about 225 g/m 2 , less than or equal to about 200 g/m 2 , less than or equal to about 175 g/m 2 , less than or equal to about 150 g/m 2 , less than or equal to about 125 g/m 2 , or less than or equal to about 100 g/m 2 . Combinations of the above-referenced ranges are also possible (e.g., a DHC of greater than about 150 g/m 2 and less than or equal to about 300 g/m 2 ). Other ranges are also possible.
  • the dust holding capacity is tested based on a Multipass Filter Test following the ISO 16889/19438 procedure (modified by testing a flat sheet sample) on a Multipass Filter Test Stand manufactured by FTI.
  • the test may be run under different conditions.
  • the testing uses ISO A3 Medium test dust manufactured by PTI, Inc. at a base upstream gravimetric dust level (BUGL) of 10 to 50 mg/liter.
  • the test fluid is Aviation Hydraulic Fluid AERO HFA MIL H-5606A manufactured by
  • the dust holding capacity values (and/or efficiency values) described herein are determined at a BUGL of 25 mg/L, a face velocity of 0.06 cm/s, and a terminal pressure of 100 kPa.
  • Suitable fiber webs may be used for the filtration of particles having a size, for example, of greater than or equal to about 50 microns, greater than or equal to about 30 microns, greater than or equal to about 20 microns, greater than or equal to about 15 microns, greater than or equal to about 10 microns, greater than or equal to about 5 microns, greater than or equal to about 4 microns, greater than or equal to about 3 microns, or greater than or equal to about 1 micron.
  • Particle counts (particles per milliliter) at the minimum particle size, x, selected (e.g., where x is 1, 2, 3, 4, 5, 7, 10, 15, 20, 25, 30, 40 or 50 microns) upstream and downstream of the media can be taken at ten points equally divided over the time of the test.
  • a particle size of x means that x micron or greater particles will be captured by the layer or media.
  • the average of upstream and downstream particle counts can be taken at each selected minimum particle size and particles greater than that size.
  • the liquid filtration efficiency test value for each minimum particle size selected can be determined by the relationship [(l-[C/Co])*100%] .
  • efficiency can be measured according to standard ISO 16889/19438 procedure.
  • a similar protocol can be used for measuring initial efficiency, which refers to the average efficiency measurements of the media at 4, 5, and 6 minutes after running the test.
  • a fiber web may have a wide range of efficiencies (e.g., liquid filtration efficiencies).
  • a fiber web has an efficiency of between about 90% and about 100%.
  • the efficiency may be, for example, greater than or equal to about 90%, greater than or equal to about 92%, greater than or equal to about 94%, greater than or equal to about 96%, greater than or equal to about 98%, greater than or equal to about 99%, greater than or equal to about 99.4%, greater than or equal to about 99.5%, greater than or equal to about 99.7%, greater than or equal to about 99.8%, greater than or equal to about 99.9%, or greater than or equal to about 99.99%.
  • Such efficiencies may be achieved for filtering particles of different sizes such as particles of 10 microns or greater, particles of 8 microns or greater, particles of 6 microns or greater, particles of 5 microns or greater, particles of 4 microns or greater, particles of 3 microns or greater, particles of 2 microns or greater, or particles of 1 micron or greater.
  • Other particle sizes and efficiencies are also possible.
  • the combined filtration arrangement including a first layer and a second layer, wherein one of the layers includes at least one fibrillated fiber may exhibit an efficiency of greater than or equal to about 90%, greater than or equal to about 92%, greater than or equal to about 94%, greater than or equal to about 96%, greater than or equal to about 98%, greater than or equal to about 99%, greater than or equal to about 99.4%, greater than or equal to about 99.5%, greater than or equal to about 99.7%, greater than or equal to about 99.8%, greater than or equal to about 99.9%, or greater than or equal to about 99.99% for particles of 4 microns or greater in some embodiments, particles of 3 microns or greater in other embodiments, particles of 2 microns or greater in yet other embodiments, or particles of 1 micron or greater in further embodiments.
  • a layer e.g., a first layer, a second layer, and/or an additional layer
  • a layer may have an efficiency within one or more of the ranges described above.
  • a fiber web may have a suitable initial efficiency.
  • the initial efficiency may range from about 30% to about 99.999% (e.g., between about 60% to about 99.9%).
  • the initial efficiency may be at least about 30%, at least about 40%, at least about 50%, at least about 60%, at least about 70%, at least about 80%, at least about 90%, at least about
  • a layer e.g., a first layer, a second layer and/or an additional layer
  • a layer may have an initial efficiency within one or more of the ranges described above.
  • a fiber web may be configured to achieve a high fuel- water separation efficiency, e.g., for separating out water from a fuel-water emulsion.
  • the fuel- water separation efficiency may range from about 30% to about 99.999% (e.g., between about 60% to about 99.9%).
  • the fuel- water separation efficiency may be at least about 30%, at least about 40%, at least about 50%, at least about 60%, at least about 70%, at least about 80%, at least about 90%, at least about 95%, at least about 98%, at least about 99%, at least about 99.9%. Other ranges are also possible.
  • the test involves sending a fuel (ultra-low sulfur diesel fuel) with a controlled water content (2500 ppm) through a pump across the media at a face velocity of 0.069cm/sec.
  • the water is emulsified into fine droplets and sent to challenge the media.
  • the water is either coalesced, or shed or both, and collects at the bottom of the housing.
  • the water content is measured both upstream and downstream of the media, via Karl Fischer titration.
  • the efficiency is the amount of water removed from the fuel- water mixture.
  • the fuel- water separation efficiency is calculated as (1 - C/2500)*100, where C is the downstream concentration of water.
  • the media can be classified as coalescing or shedding based on the amount of water collected. If the water collection is more upstream, then the media is primarily shedding. If the water collecting is more down-stream, then the media is primarily coalescing. Combinations can also occur where the media can be both coalescing and shedding.
  • the fiber webs may exhibit suitable air permeability characteristics.
  • the air permeability may range from between about 0.1 cubic feet per minute per square foot (cfm/sf) and about 250 cfm/sf (e.g., between about 0.5 cfm/sf and about 50 cfm/sf, between about 50 cfm/sf and about 125 cfm/sf, between about 5 cfm/sf and about 150 cfm/sf, between about 10 cfm/sf and about 150 cfm/sf, or between about 50 cfm/sf and about 150 cfm/sf).
  • the air permeability may be greater than or equal to about 0.5 cfm/sf, greater than or equal to about 2 cfm/sf, greater than or equal to about 5 cfm/sf, greater than or equal to about 10 cfm/sf, greater than or equal to about 25 cfm/sf, greater than or equal to about 50 cfm/sf, greater than or equal to about 75 cfm/sf, greater than or equal to about 100 cfm/sf, greater than or equal to about 150 cfm/sf, greater than or equal to about 200 cfm/sf, or greater than or equal to about 250 cfm/sf.
  • the air permeability may be less than or equal to about 250 cfm/sf, less than or equal to about 200 cfm/sf, less than or equal to about 175 cfm/sf, less than or equal to about 150 cfm/sf, less than or equal to about 125 cfm/sf, less than or equal to about 100 cfm/sf, less than or equal to about 75 cfm/sf, less than or equal to about 50 cfm/sf, less than or equal to about 25 cfm/sf, or less than or equal to about 5 cfm/sf. Combinations of the above-referenced ranges are also possible (e.g., an air permeability of greater than or equal to 5 cfm/sf and less than or equal to about 200 cfm/sf). Other ranges are also possible.
  • the permeability is measured according to the Standard TAPPI T-251.
  • the permeability is an inverse function of flow resistance and can be measured with a Frazier Permeability Tester (e.g., TexTest Instrument, FX 3300).
  • the Frazier Permeability Tester measures the volume of air per unit of time that passes through a unit area of sample at a fixed differential pressure across the sample.
  • Permeability can be expressed in cubic feet per minute per square foot at a 0.5 inch water differential.
  • a layer e.g., a first layer and/or a second layer
  • an additional layer e.g., a third layer, a fourth layer, etc.
  • the fiber web may have an air permeability between about 0.5 cubic feet per minute per square foot (cfm/sf) and about 1500 cfm/sf (e.g., between about 0.5 cfm/sf and about 70 cfm/sf, between about 5 cfm/sf and about 700 cfm/sf, or between about 5 cfm/sf and about 1300 cfm/sf).
  • the air permeability may be greater than or equal to about 0.5 cfm/sf, greater than or equal to about 5 cfm/sf, greater than or equal to about 10 cfm/sf, greater than or equal to about 50 cfm/sf, greater than or equal to about 70 cfm/sf, greater than or equal to about 100 cfm/sf, greater than or equal to about 300 cfm/sf, greater than or equal to about 500 cfm/sf, greater than or equal to about 700 cfm/sf, or greater than or equal to about 1000 cfm/sf.
  • the air permeability may be less than or equal to about 1500 cfm/sf, less than or equal to about 1300 cfm/sf, less than or equal to about 1000 cfm/sf, less than or equal to about 800 cfm/sf, less than or equal to about 400 cfm/sf, less than or equal to about 100 cfm/sf, or less than or equal to about 50 cfm/sf. Combinations of the above-referenced ranges are also possible. Other ranges are also possible.
  • the fiber webs described herein may have a certain relationship between mean flow pore size to permeability.
  • the relationship between mean flow pore size and permeability may be expressed as [mean flow pore
  • the mean flow pore size of the fiber media may be divided by the square root of the permeability of the media.
  • a fiber web having a higher efficiency may have a lower [mean flow pore ⁇ m)/(permeability (cfm/sf)) 0'5 ] value if all other factors are equal.
  • the fiber webs described herein have a [mean flow pore
  • a fiber web has a [mean flow pore ⁇ m)/(permeability (cfm/sf)) 0'5 ] value of between about 0.5 and about 3.0.
  • a fiber web has a [mean flow pore ⁇ m)/(permeability (cfm/sf)) 0'5 ] value of less than or equal to about 3, less than or equal to about 2.5, less than or equal to about 2, less than or equal to about 1.8, less than or equal to about 1.6, less than or equal to about 1.5, less than or equal to about 1.4, less than or equal to about 1.2, less than or equal to about 1.0, less than or equal to about 0.9, less than or equal to about 0.8, less than or equal to about 0.7, or less than or equal to about 0.6.
  • a fiber web has a [mean flow pore ⁇ m)/(permeability (cfm/sf)) 0'5 ] value of greater than or equal to about 0.5, greater than or equal to about 0.6, greater than or equal to about 0.8, greater than or equal to about 1.0, greater than or equal to about 1.2, greater than or equal to about 1.5, or greater than or equal to about 2.0. Combinations of the above-referenced ranges are also possible (e.g., a [mean flow pore ⁇ m)/(permeability (cfm/sf)) 0'5 ] value of greater than about 0.5 and less than or equal to about 1.5). Other values are also possible.
  • a layer e.g., a first layer and/or a second layer
  • Fiber webs described herein may be produced using suitable processes, such as using a wet laid process or a non-wet laid process (e.g., a dry laid process, a spinning process, a meltblown process, or any other suitable process).
  • a wet laid process involves mixing together of fibers of one or more type; for example, non- fibrillated fibers (e.g., mono-component and/or bi-component fibers) may be mixed together with fibrillated fibers, or any other components (e.g., other types of synthetic fibers), to provide a fiber slurry.
  • non- fibrillated fibers e.g., mono-component and/or bi-component fibers
  • fibrillated fibers e.g., mono-component and/or bi-component fibers
  • fibrillated fibers e.g., mono-component and/or bi-component fibers
  • fibrillated fibers e.g., mono-component and/or bi-component fibers
  • the slurry may be, for example, an aqueous-based slurry.
  • fibrillated fibers, optional non-fibrillated fibers, and any other appropriate fibers are optionally stored separately, or in combination, in various holding tanks prior to being mixed together (e.g., to achieve a greater degree of uniformity in the mixture).
  • a first fiber e.g., fibrillated fibers or non-fibrillated fibers
  • a second fiber e.g., fibrillated fibers
  • the first fibers and the second fibers may subsequently be combined together into a single fibrous mixture.
  • Appropriate fibers may be processed through a pulper before and/or after being mixed together.
  • combinations of fibers such as non-fibrillated fibers, fibrillated fibers and/or other synthetic fibers, are processed through a pulper and/or a holding tank prior to being mixed together. It can be appreciated that other components may also be introduced into the mixture.
  • other components may also be introduced into the mixture.
  • fibers types may be used in fiber mixtures, such as the fiber types described herein.
  • two or more layers are formed by a wet laid process.
  • a first dispersion e.g., a pulp
  • a solvent e.g., an aqueous solvent such as water
  • a second dispersion e.g., another pulp
  • a solvent e.g., an aqueous solvent such as water
  • Vacuum is continuously applied to the first and second dispersions of fibers during the above process to remove the solvent from the fibers, thereby resulting in an article containing first and second layers.
  • the article thus formed is then dried and, if necessary, further processed (e.g., calendered) by using known methods to form multi-layered fiber webs.
  • such a process may result in a gradient in at least one property across the thickness of the two or more layers.
  • Any suitable method for creating a fiber slurry may be used. In some embodiments, any suitable method for creating a fiber slurry may be used.
  • further additives are added to the slurry to facilitate processing.
  • the temperature may also be adjusted to a suitable range, for example, between 33 °F and 100 °F (e.g., between 50 °F and 85 °F). In some cases, the temperature of the slurry is maintained. In some instances, the temperature is not actively adjusted.
  • the wet laid process uses similar equipment as in a conventional papermaking process, for example, a hydropulper, a former or a headbox, a dryer, and an optional converter.
  • a fiber web can also be made with a laboratory handsheet mold in some instances.
  • the slurry may be prepared in one or more pulpers. After appropriately mixing the slurry in a pulper, the slurry may be pumped into a headbox where the slurry may or may not be combined with other slurries. Other additives may or may not be added.
  • the slurry may also be diluted with additional water such that the final concentration of fiber is in a suitable range, such as for example, between about 0.1% to 0.5% by weight.
  • Wet laid processes may be particularly suitable for forming gradients of one or more properties in a fiber web, such as those described herein.
  • the same slurry is pumped into separate headboxes to form different layers and/or a gradient in a fiber web.
  • two or more different slurries may be pumped into separate headboxes to form different layers and/or a gradient in a fiber web.
  • a first layer can be formed from a fiber slurry, drained and dried and then a second layer can be formed on top from a fiber slurry.
  • a first layer can be formed and a second layer can be formed on top, drained and dried.
  • the pH of the fiber slurry may be adjusted as desired.
  • fibers of the slurry may be dispersed under generally neutral conditions.
  • the slurry Before the slurry is sent to a headbox, the slurry may optionally be passed through centrifugal cleaners and/or pressure screens for removing unfiberized material.
  • the slurry may or may not be passed through additional equipment such as refiners or deflakers to further enhance the dispersion or fibrillation of the fibers.
  • deflakers may be useful to smooth out or remove lumps or protrusions that may arise at any point during formation of the fiber slurry. Fibers may then be collected on to a screen or wire at an appropriate rate using any suitable equipment, e.g., a fourdrinier, a rotoformer, a cylinder, or an inclined wire fourdrinier.
  • the process involves introducing binder (and/or other components) into a pre-formed fiber layer (e.g., including a fibrillated fiber with a non- fibrillated fiber).
  • a pre-formed fiber layer e.g., including a fibrillated fiber with a non- fibrillated fiber.
  • different components included in the binder which may be in the form of separate emulsions, are added to the fiber layer using a suitable technique.
  • each component of the binder resin is mixed as an emulsion prior to being combined with the other components and/or fiber layer.
  • the components included in the binder may be pulled through the fiber layer using, for example, gravity and/or vacuum.
  • one or more of the components included in the binder resin may be diluted with softened water and pumped into the fiber layer.
  • a binder may be introduced to the fiber layer by spraying onto the formed media, or by any other suitable method, such as for example, size press application, foam saturation, curtain coating, rod coating, amongst others.
  • a binder material may be applied to a fiber slurry prior to introducing the slurry into a headbox.
  • the binder material may be introduced (e.g., injected) into the fiber slurry and impregnated with and/or precipitated on to the fibers.
  • a binder resin may be added to a fiber web by a solvent saturation process, as described in more detail herein.
  • a non-wet laid process is used to form one or more layers of a fiber web.
  • a non-wet laid process involves a dry laid process, such as a carding process.
  • an air laid process is used.
  • non-fibrillated synthetic fibers may be mixed along with fibrillated fibers (e.g., lyocell) while air is blown onto a conveyor, and a binder is then applied.
  • the fibers are manipulated by rollers and extensions (e.g., hooks, needles) associated with the rollers prior to application of the binder.
  • forming the fiber webs through a non-wet laid process may be more suitable for the production of a highly porous media.
  • a first and/or second layer of a fiber web may be formed by a non-wet laid process.
  • the first and/or second layer may be impregnated (e.g., via saturation, spraying, etc.) with any suitable binder resin, as discussed above.
  • the fiber web may be further processed according to a variety of known techniques.
  • additional layers can be formed and/or added to a fiber web using processes such as lamination, co-pleating, or collation.
  • two layers are formed into a composite article by a wet laid process as described above, and the composite article is then combined with a third layer by any suitable process (e.g., lamination, co-pleating, or collation).
  • a fiber web or a composite article formed by the processes described herein may be suitably tailored not only based on the components of each fiber layer, but also according to the effect of using multiple fiber layers of varying properties in appropriate combination to form fiber webs having the characteristics described herein.
  • further processing may involve pleating the fiber web.
  • the fiber web may be suitably pleated by forming score lines at appropriately spaced distances apart from one another, allowing the fiber web to be folded. It should be appreciated that any suitable pleating technique may be used.
  • a fiber web can be post-processed such as subjected to a corrugation process to increase surface area within the web.
  • the depth of the pleats or corrugations may vary from about 0.01 mm to about 7 mm.
  • the depth of the pleats or corrugations may be at least about 0.01 mm, at least about 0.1 mm, at least about 1 mm, at least about 2 mm, or at least about 5 mm, and/or less than or equal to about 7 mm, less than or equal to about 5 mm, less than or equal to about 3 mm, or less than or equal to about 1 mm. Combinations of the above-referenced ranges are possible. Other ranges are also possible.
  • the periodicity of the pleats or corrugations may also vary, e.g., from about 2 cycles/inch to about 8 cycles per inch.
  • a fiber web may be embossed or subject to a dimpling process to produce protrusions and/or indentations in the fiber web.
  • the depth of the protrusions or indentations may vary from about 0.01 mm to about 7 mm.
  • the depth of the protrusions or indentations may be at least about 0.01 mm, at least about 0.1 mm, at least about 1 mm, at least about 2 mm, or at least about 5 mm, and/or less than or equal to about 7 mm, less than or equal to about 5 mm, less than or equal to about 3 mm, or less than or equal to about 1 mm.
  • the fiber web may include other parts in addition to the one or more layers described herein.
  • further processing includes incorporation of one or more structural features and/or stiffening elements.
  • the fiber web may be combined with additional structural features such as polymeric and/or metallic meshes.
  • a screen backing may be disposed on the fiber web, providing for further stiffness.
  • a screen backing may aid in retaining the pleated configuration.
  • a screen backing may be an expanded metal wire or an extruded plastic mesh.
  • fiber webs used as filter media can be incorporated into a variety of filter elements for use in various filtering applications.
  • Exemplary types of filters include hydraulic mobile filters, hydraulic industrial filters, fuel filters (e.g., automotive fuel filters), oil filters (e.g., lube oil filters or heavy duty lube oil filters), chemical processing filters, industrial processing filters, medical filters (e.g., filters for blood), air filters, and water filters.
  • filter media described herein can be used as coalescer filter media.
  • the filter media may be suitable for filtering gases or liquids.
  • the fiber webs and filter media disclosed herein can be incorporated into a variety of filter elements for use in various applications including hydraulic and non- hydraulic filtration applications including fuel applications, lube applications, air applications, amongst others.
  • hydraulic filters e.g., high-, medium-, and low-pressure filters
  • Exemplary uses of hydraulic filters include mobile and industrial filters.
  • the fiber webs mechanically trap particles on or in the layers as fluid flows through the filter media.
  • the fiber webs need not be electrically charged to enhance trapping of contamination.
  • the filter media are not electrically charged.
  • the filter media may be electrically charged.
  • This example demonstrates a method of fabricating dual layer fiber webs including a first layer comprising cellulose pulp fibers and a second layer comprising fibrillated aramid fibers.
  • Dual layer handsheets were made using a laboratory handsheet mold. The fibers for the first layer were mixed in a blender with 1000 mL of water for 2 minutes. The slurry was placed in a handsheet mold and the fiber web was formed on a wire. The fiber web was drained and dried. Then the fiber web was placed back into the handsheet mold, and the second slurry was placed into the handsheet mold and formed on top of the first layer. The resulting fiber web was drained and dried.
  • the resulting fiber webs included a first layer comprising cellulose pulp and a second layer comprising fibrillated aramid fibers.
  • the amount of material added for the first layer was 18.9 g (HP-11 softwood pulp, HBA softwood pulp, and Kuralon SPG-056 polyvinyl alcohol fiber in the ratio of [56.5:42.5: 1]) and the amount of material (100% aramid pulp) added for the second layer was 3.8g.
  • the Canadian Standard Freeness for the fibrillated aramid fibers was an average of 80 mL.
  • the sample had a permeability of 2.5 CFM, a mean flow pore of 1.1 microns, an average Multipass efficiency of 99.7% at 4 micron or greater particles, a dust hold capacity of 115 g/m 2 , and a basis weight of 137.5 lb/ream (with the second layer having a basis weight of 12.5 lb/ream and the first layer having a basis weight of 125 lb/ream).
  • Multipass Filter Tests for determining efficiency and dust holding capacity were performed at 10 mg/L base upstream gravimetric level (BUGL), a face velocity of 0.16 cm/s, a 200 kPa terminal pressure and a flow rate of 1 L/min following the ISO
  • This example shows that relatively high efficiencies at 4 microns can be obtained in fiber media including fibrillated fibers in one layer. This example also shows that a relatively low Perm. Pore Index and a relatively high dust holding capacity can be obtained in such media. This example also shows that such efficiencies and dust holding capacities can be obtained in fiber webs that do not include any glass fibers.
  • This example shows the fabrication of a wet laid fiber web including a first layer comprising a mixture of Robur Flash (cellulose) fibers: HP- 11 softwood fibers: PET (0.6dx5mm) fibers, and a second layer comprising fibrillated lyocell fibers.
  • cellulose cellulose
  • HP- 11 softwood fibers HP- 11 softwood fibers: PET (0.6dx5mm) fibers
  • fibrillated lyocell fibers Several samples were made varying the level of fibrillation of the fibers in the first layer.
  • a wet laid papermaking process was used to fabricate dual layer fiber webs.
  • the first layer was formed on a Fourdrinier machine and drained, and the second layer was formed on top using another headbox.
  • the resulting fiber webs included a first layer comprising a mixture of Robur Flash (cellulose) fibers: HP- 11 softwood fibers: PET (0.6dx5mm) fibers, and a second layer comprising fibrillated lyocell fibers.
  • the lyocell fibers in the second layer had an average Canadian Standard Freeness of 40 mL.
  • the weight ratios of the fibers in the first layer were 1:1:0.46 by weight.
  • the basis weight ratios of the second layer to first layer were varied, as were the conditions for refining (fibrillating) the fibers in the first layer.
  • the target basis weight for the combined layers was 60 lb/ream for each sample. The following conditions were tested: a. Sample 1: Second layenfirst layer basis weight ratio of 1:2, with no fibrillation of fibers in the first layer.
  • Sample 2 Second layenfirst layer basis weight ratio of 1:2 with some fibrillation of fibers in the first layer.
  • the Perm. Pore Index value was 2.33.
  • Fiber webs were made using a combination of lyocell and eucalyptus fibers as a first, top layer.
  • the first layer was formed on a second, bottom layer that did not include fibrillated fibers.
  • Eucalyptus is a hardwood pulp with very small diameter and can help in obtaining a tight top layer.
  • the lyocell fibers in the first, top layer had an average CSF value of about 40 mL.
  • the amounts of lyocell and eucalyptus fibers in the first layer were varied.
  • the basis weight of the first layer was also varied.
  • the basis weight of the second, bottom layer was 55 lb/ream layer and was formed of Robur Flash (cellulose) fibers: HP- 11 fibers: PET (0.6dx5mm) fibers in the ratio 1: 1:0.46 by weight.
  • Table 1 shows the fraction of lyocell and eucalyptus fibers in the first, top layer, the basis weight of the first, top layer, and the resulting Perm. Pore Index measured for each of the samples.
  • the first, top layer included lyocell fibers and the basis weight of the layer was varied between 10 lb/ream and 20 lb/ream in different samples.
  • the second, bottom layer was made from HPZ, softwood kraft pulp and eucalyptus fibers in the weight ratio of 0.34:0.15:0.52 and remained the same for all samples.
  • the Canadian Standard Freeness (CSF) of the lyocell fibers in the top layer was varied and was 40 mL, 60 mL 200 mL, or 250 mL.
  • the Perm. Pore Index values for each of the samples were measured as shown in Table 2.
  • the fiber webs have Perm. Pore Index values of less than 3. Furthermore, the fibers webs achieve high efficiency values. This example also shows that such values can be obtained in fiber webs that do not include any glass fibers.
  • This example demonstrates a method of fabricating a dual layer fiber web including a first layer comprising cellulose pulp fibers and a second layer comprising fibrillated lyocell fibers, which was then collated with a meltblown layer positioned downstream of the second layer.
  • Dual layer handsheets were made using a laboratory handsheet mold.
  • the fibers for the first layer (10.8 g of cellulose fibers including 15% Prince George Pulp, 51% Eucalyptus fiber, 33% porosanier fiber) were mixed in a blender with 1000 mL of water for 2 minutes to form a first slurry.
  • the first slurry was placed in a handsheet mold and the fiber web (i.e., the first layer) was formed on a wire.
  • the fiber web was drained and dried.
  • the fiber web was then placed back into the handsheet mold to act as a substrate for the second layer.
  • the second slurry contained 7.57 g of fibrillated lyocell pulp with 21% solids in
  • the second slurry was placed into the handsheet mold to form a second layer on top of the first layer.
  • the resulting dual layer fiber web was drained and dried.
  • the resulting dual layer web had a basis weight of 107.4 gsm and an air permeability of 15.4 cfm/sf.
  • a layer of meltblown fibers on a scrim having a basis weight of 36.8 gsm and an air permeability of 10 cfm/sf was collated with the dual layer web to form an overall composite.
  • the meltblown layer was positioned downstream of the second layer of dual layer web in the composite.
  • the average fiber diameter of the meltblown fibers was 1 micron.
  • the composite had an air permeability of 6 cfm/sf, a dust holding capacity of 156 gsm, and a basis weight of 143.6 gsm.
  • the initial efficiency of the composite was 99.47% at 4 micron or greater particles.
  • the liquid filtration efficiency of the composite was 99.81% at 4 micron or greater particles.
  • Multipass Filter Tests for determining initial efficiency, liquid filtration efficiency, and dust holding capacity were performed at 50 mg/L base upstream gravimetric level (BUGL), a face velocity of 0.06 cm/s, and a flow rate of 1 L/min following the ISO 16889/19438 procedure.
  • the initial efficiency is the efficiency at 4, 5 and 6 minutes after running the test.
  • the liquid filtration efficiency is the efficiency of the media after reaching a 100 kPa terminal pressure.
  • CSF 200 mL
  • filter media including a meltblown layer can improve fuel- water separation efficiency of the media.
  • the procedure described in Example 5 was used to form a composite media.
  • the composite media included a dual layer fiber web including a first layer comprising cellulose pulp fibers and a second layer comprising fibrillated lyocell fibers, which was then collated with a meltblown layer positioned downstream of the second layer.
  • the dual layer fiber web of this example had similar characteristics as the dual layer fiber web described in Example 5, except the fibrillated lyocell fibers had an average Canadian Standard Freeness of 100 mL.
  • the meltblown layer did not include a scrim, and had a basis weight of 106 gsm, an air permeability of 25.8 cfm/sf, and an average fiber diameter of 4-8 microns.
  • the composite including the dual layer fiber web and meltblown layer had an initial liquid filtration efficiency of 99.5%, a liquid filtration efficiency of 99.7%, and a fuel- water separation efficiency of 63.2%. Without the meltblown layer, the dual layer fiber web had a fuel-water separation efficiency of 32.5%.

Abstract

La présente invention a trait à des bandes de fibres qui sont utilisées dans des milieux filtrants. Selon certains modes de réalisation, les bandes de fibres incluent des fibres fibrillées et éventuellement des fibres non fibrillées, parmi d'autres constituants facultatifs (par exemple une résine liante). Selon certains modes de réalisation, les bandes de fibres contiennent des quantités limitées de fibres de verre ou aucune fibre de verre. Les caractéristiques et quantités respectives des fibres fibrillées sont sélectionnées de manière à conférer des propriétés souhaitées, y compris, parmi d'autres avantages, des propriétés mécaniques et des propriétés de filtration (par exemple une capacité et une efficacité de colmatage).
PCT/US2014/071547 2013-12-19 2014-12-19 Fibres fibrillées pour milieux de filtration de liquides WO2015095732A1 (fr)

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