Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B82—NANOTECHNOLOGY
  • B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
  • B82Y30/00—Nanotechnology for materials or surface science, e.g. nanocomposites
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D39/00—Filtering material for liquid or gaseous fluids
  • B01D39/02—Loose filtering material, e.g. loose fibres
• • 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
  • B01D69/00—Semi-permeable membranes for separation processes or apparatus characterised by their form, structure or properties; Manufacturing processes specially adapted therefor
  • B01D69/04—Tubular membranes
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D69/00—Semi-permeable membranes for separation processes or apparatus characterised by their form, structure or properties; Manufacturing processes specially adapted therefor
  • B01D69/10—Supported membranes; Membrane supports
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D69/00—Semi-permeable membranes for separation processes or apparatus characterised by their form, structure or properties; Manufacturing processes specially adapted therefor
  • B01D69/12—Composite membranes; Ultra-thin membranes
• • 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
  • B01D2239/02—Types of fibres, filaments or particles, self-supporting or supported materials
  • B01D2239/025—Types of fibres, filaments or particles, self-supporting or supported materials comprising nanofibres
• • 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
  • B01D2239/0604—Arrangement of the fibres in the filtering material
  • B01D2239/0631—Electro-spun
• • 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
  • B01D2239/0604—Arrangement of the fibres in the filtering material
  • B01D2239/064—The fibres being mixed
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D2239/00—Aspects relating to filtering material for liquid or gaseous fluids
  • B01D2239/06—Filter cloth, e.g. knitted, woven non-woven; self-supported material
  • B01D2239/065—More than one layer present in the filtering material
  • B01D2239/0668—The layers being joined by heat or melt-bonding
• • 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
  • B01D2239/069—Special geometry of layers
  • B01D2239/0695—Wound layers
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D2239/00—Aspects relating to filtering material for liquid or gaseous fluids
  • B01D2239/12—Special parameters characterising the filtering material
  • B01D2239/1233—Fibre diameter

Definitions

• This invention generally relates to a filter media, and in particular to a compressed composite media comprising a substrate and fine fibers, and method of making the same.
• Hydrocarbon fuels such as diesel fuel, jet fuel, and gasoline
• the water may be introduced in the hydrocarbon fuels, for example, by leakage, accidental contamination, or atmospheric condensation.
• the hydrocarbon fuels can dissolve about 75 to 150 parts per million (ppm) of water at room temperature. Water solubility can increase about 1 ppm per 1° F rise in temperature, and decrease about 1 ppm per 1° F fall in temperature. Excess water or undissolved water may accumulate in lower parts of a fuel handling system as a result of temperature changes over a period of time.
• Undissolved water can be harmful to engines. Diesel engine injectors may be damaged by steam formation, jet turbine engines may flame-out, and gasoline engines may suffer ignition problems. Many water separation devices and filters have been developed to remove undissolved or free water from the fuel and prevent such engine problems. Simple mechanical devices base on gravity or centrifugal force separation are sufficient if free water is present as a discrete second phase. However, free water is often emulsified by pumps and valves, may remain as a stable emulsion, especially in diesel or jet fuel. Two stage coalescer/separators are designed to remove water emulsions. The coalescer breaks the emulsion by preferential wetting of fibrous materials such as fiber glass.
• the water is accumulated into large droplets and is removed by gravity separation against a hydrophobic separator material such as PTFE coated wire cloth or silicone impregnated paper.
• a hydrophobic separator material such as PTFE coated wire cloth or silicone impregnated paper.
• wetting agents or surfactants may interfere with the coalescence of water emulsions, especially in diesel fuel or jet fuel.
• a coalescer including hydrophobic fluoropolymer fine fibers to capture and remove water from fuel emulsions is disclosed in Fluoropolymer Fine Fiber, U.S. Patent Application Publication No. 2009/0032475, to Ferrer et al.
• Filter media including fine fibers formed using an electrostatic spinning process is also known.
• Such prior art includes Filter Material Construction and Method, U.S. Patent No. 5,672,399; Cellulosic/Polyamide Composite, U.S. Patent Publication No.
• Nanofiber Layer U.S. Provisional Patent No. 61,047,455, the entire disclosures of which are incorporated herein by reference thereto. As shown in these references nano fibers are commonly laid upon a finished preformed filtration media substrate.
• the invention provides improved coalescing medias and method of making the coalescing media.
• a compressed nanofiber composite filter media according to various aspects
• the compressed filter media includes at least one substrate and fine fibers carried thereby.
• the compressed filter media includes multiple substrate layers, each of which carrying fine fibers.
• the multiple substrate and fine fiber layers are compressed together to form the compressed composite filter media.
• the compressed filter media according to various embodiments of the present invention is particularly well suited for a coalescing media to coalesce water in various hydrocarbon fuels.
• the compressed filter media can also be used in other filtration applications.
• the compressed filter media can make a very efficient water filter element.
• the substrate layers employed are relative open materials with coarse fibers to provide support while at the same time not being overly restrictive to fluid flow especially as layers are stacked and/or compressed.
• This structure spaces nano-fibers apart and affords the ability to provide for a much heavier total coverage of nano-fibers per square unit of area while at the same time not being overly restrictive.
• a relatively thin substrate may be used (and compression used), such that the fine fibers throughout the media is spaced relatively close and close enough to facilitate coalescing; and thickness of the media as a whole is suitable for coalescing filtration applications and filter element arrangement.
• Many embodiments also employ hydrophilic fine fibers that attract as opposed to repelling water. By using multiple layers of fine fibers at sufficient coverage, water molecules or fine droplets grow within this structure and are effectively coalesced out of a fluid stream.
• the multiple substrate layers and the fine fibers may and preferably are compressed together to form a coalescing filter media.
• the coalescing filter media is compacted and high in solidity and includes a sufficient fine fiber coverage to provide a sufficient fiber surface area to coalesce emulsified water in a hydrocarbon fuel stream.
• the fine fibers are preferably electrospun nanofibers formed of a hydrophilic material, such as polyamide-6. The hydrophilic fine fibers further facilitate formation and growth of water droplets.
• a method of forming a coalescing filter media comprises steps of
• the method further includes steps of generating sufficient fine fiber coverage and tightness through the compacting process to coalesce water droplets from a fluid stream, and structuring the coarse fibers and the fine fibers into a coalescing filter media that is operable to remove water from a fluid stream.
• the substrate comprise a fiber entanglement that is bonded together, wherein the fine fibers are deposited onto the substrate during the step of applying the fine fibers.
• the substrate can be a scrim formed of bi-component fibers comprising a high melt component and a low melt component, wherein the fine fibers are deposited on a surface of the scrim and carried by the scrim.
• the step of compacting can involve laminating multiple layers of the scrim carrying the fine fibers, and compressing the multiple layers of the scrim and the fine fibers using a set of calendering rollers.
• the multiple layers of the scrim and the fine fibers can be heated to or near a melting temperature of the low melt component, wherein the low melt component melts or softens to act as a bonding agent to bond layers together.
• the multiple layers are heated before being compressed.
• the multiple layers can be heated in an oven and compressed subsequently via a set of calendering rollers.
• a thickness of the laminated multiple layers may increase as the scrims expand and loft during heating.
• the subsequent compression of the lofted multiple layers reduces the lofted thickness, however, the final thickness of the compressed multiple layers may be less, equal, or greater than the original thickness of the laminated multiple layers before heating.
• the multiple layers are heated and compressed simultaneously.
• the multiple layers can be heated and compressed using a set of heated calendering rollers.
• the multiple layers can be compressed first then heated, wherein the thickness of the compressed multiple layers may increase during heating.
• some embodiments can including more than one heating steps.
• the multiple layers can be heated before compressing, and further heated during compressing via the set of heated calendering rollers.
• each scrim layer carries the fine fibers having a relatively heavy fine fiber coverage between about 0.075 g/m 2 and .225 g/m 2 .
• a total fine fiber coverage of the coalescing filter media can be between about 0.75 g/m 2 and 2.25 g/m 2 .
• the layers of the scrim and the fine fibers are compressed together to form a coalescing filter media having a thickness to between about 3/16" and 1 ⁇ 2".
• the scrim carrying the fine fibers is folded into multiple folds and compressed to form a coalescing filter media.
• the coalescing filter media can include a fine fiber to fine fiber laminated surface and a scrim to scrim laminated surface.
• the substrate is a web of coarse fibers comprising a loose entanglement of the coarse fibers, wherein the fine fibers are applied to the loose entanglement of the coarse fibers during the step of applying the fine fibers.
• the web of coarse fibers applied with the fine fibers can be folded into multiple folds and compressed together, wherein the fine fibers and the coarse fibers are integrated to form a single integrated coalescing media.
• a method of forming a coalescing filter media includes steps of electrostatically spinning a web of fine fibers having an average diameter of less than 1 micron, applying the fine fibers to a substrate formed of coarse fibers having an average fiber diameter greater than 1 micron that are bonded together, and lapping the combination of the fine fiber applied substrate such that the fine fibers overlap.
• the method can further include a step of unwinding a roll of substrate from an unwind station and transferring the substrate to an electrospinning station, wherein the substrate is kept afloat via a line tension.
• the substrate can be a scrim comprising bi-component fibers.
• the bi-component fibers can include a high melt polyester core and a low melt polyester sheath.
• the step of applying the fine fibers can provide a fine fiber coverage between about 0.03 g/m 2 and 0.25 g/m 2 , preferably between about 0.075 g/m 2 and .225 g/m 2 , wherein the fine fibers are carried by the scrim.
• the step of lapping can involve folding the scrim carrying the fine fibers into 2-20 folds, wherein the folding provides a fine fiber to fine fiber laminated surface and a scrim to scrim laminated surface, wherein the folded layers are heated and compressed to form a coalescing media.
• a thickness of the folded layers can be adjusted from the original thickness (thickness of each layer x number of layers) by about 50% to 300%, preferably about 70%) to 200%), and more preferably about 80%> to 150%.
• the thickness can increase after heating than reduced during compressing. In some cases, the increase in thickness during heating can be so great that the final thickness may be still greater than the original thickness even after compressing.
• Two or more folded or unfolded scrims may also be employed in a stacked combination to achieve heavy fine fiber coverage per area.
• the coalescing media is formed to have a total fine fiber coverage between about 0.09 g/m 2 and 5.25 g/m 2 , preferably between about 0.75 g/m 2 and 2.25 g/m 2 .
• the step of electrostatically spinning fine fibers preferably involves spinning fine fibers from a solution including a polyamide-6.
• a coalescing filter media in another embodiment, includes at least one substrate containing coarse fibers having an average fiber diameter of greater than 1 micron, and fine fibers carried by the substrate.
• the fine fibers are hydrophilic fibers having an average fiber diameter of less than 1 micron and provide a sufficient fiber surface area to coalesce emulsified water in a hydrocarbon fuel.
• the hydrophilic fibers facilitate formation and growth of water droplets.
• the coalescing filter media can further include a drainage layer arranged on a downstream surface of the coalescing filter media. Such drainage layer can facilitate growth of the water droplet size.
• the drainage layer is formed of a cellulous material or a fiber glass material.
• the fine fibers are preferably electrospun nanofibers formed of a hydrophilic polymer, such as polyamide-6.
• the coalescing filter media includes the fine fibers having a total fine fiber coverage between about 0.09 g/m 2 and 5.25 g/m 2 , preferably between about 0.75 g/m 2 and 2.25 g/m 2 .
• the substrate is preferably a scrim comprising bi-component fibers, which includes a high melt component and a low melt component.
• the bi-component fibers can include a high melt polyester core and a low melt polyester sheath.
• the substrate layers and the fine fibers are heated and compressed together to form a coalescing media, wherein the low melt polyester sheath melts or softens to bond the coarse fibers and the fine fibers.
• the coalescing filter media can include multiple layers of substrate, wherein each of the multiple substrate layers carry a layer of fine fibers having a fine fiber coverage between about 0.075 g/m 2 and .225 g/m 2 . In one embodiment, each of the fine fiber layer is sandwiched between the substrate layers and or a media layer. In other embodiment, the coalescing filter media can include a fine fiber to fine fiber laminated surface and a substrate to substrate laminated surface.
• the coalescing filter media includes 10 layers of substrate.
• Each of the substrate layer is formed of a scrim comprising bi-component fibers and carries fine fibers.
• the fine fibers on each substrate layer is formed of electrospun polyamide-6 nano fibers.
• the fine fibers carried by the 10 substrate layers provide a total fine fiber coverage between about 0.75 g/m 2 and 2.25 g/m 2 .
• the coalescing filter media can further including a drainage layer arranged on a downstream surface of the coalescing filter media formed of a fiber glass mat. In such embodiment, the coalescing filter media can have a total thickness between about 3/16" and 1 ⁇ 2".
• a coalescing filter media including at least one substrate containing coarser fibers having an average fiber diameter of greater than 1 micron and fine fibers carried by the substrate.
• the fine fibers have an average fiber diameter of less than 1 micron, and at least some of the fine fibers are embedded at least partially within the coarse fibers in a compressed state.
• at least some of the fine fibers can form a three dimensional matrix of fine fibers extending into the substrate as opposed to a planar layer. Further, at least some of the fine fibers can be generally sandwiched between layers of the substrate.
• the fine fibers have a melting point higher than a melting point of at least one component of the coarse fibers, and the fine fibers are permanently affixed and oriented. Further, the at least one substrate and the fine fibers are calendered together to form the compressed state.
• FIG. 1 is a schematic cross-sectional view (e.g. relative illustrated thickness not to scale) of a filter media including tightly compacted multiple scrim layers carrying fine fibers according to an embodiment of the present invention
• FIG. 2 is a schematic cross-sectional view of the coalescing filter media of FIG. 1 in a pre-compressed state, which is compressed to a compressed state;
• FIG. 3 is a schematic illustration of a concentric sheath/core type bi-component fiber of a substrate according to an embodiment of the present invention
• FIG. 4 is a schematic illustration of an eccentric sheath/core type bi-component fiber of a substrate according to an embodiment of the present invention
• FIG. 5 is a schematic illustration of a side-by- side type bi-component fiber of a substrate according to an embodiment of the present invention
• FIG. 6 is a schematic illustration of a pie wedge type bi-component fiber of a substrate according to an embodiment of the present invention.
• FIG. 7 is a schematic illustration of a hollow pie wedge type bi-component fiber of a substrate according to an embodiment of the present invention.
• FIG. 8 is a schematic illustration of an islands/sea type bi-component fiber of a substrate according to an embodiment of the present invention.
• FIG. 9 is a schematic illustration of a trilobal type bi-component fiber of a substrate according to an embodiment of the present invention.
• FIG. 10 is a schematic illustration of tipped typed bi-component fiber of a substrate according to an embodiment of the present invention.
• FIG. 1 1 is a schematic cross-sectional view of a coalescing filter media including tightly compressed multiple scrim layers and fine fibers and a downstream porous layer according to an embodiment of the present invention
• FIG. 12 is a schematic illustration of a system for making a coalescing filter media according to an embodiment of the present invention.
• FIG. 13 is a schematic illustration of a system for making a coalescing filter media according to a different embodiment of the present invention.
• FIG. 14 is a schematic illustration of a system for making a coalescing filter media according to yet another embodiment of the present invention.
• FIG. 15(A) is a Scanning Electron Microscopic image showing bi-component fibers and the fine fibers of a composite media produced using the system of FIG. 12 taken at a magnification level x300;
• FIG. 15(B) is a Scanning Electron Microscopic image showing bi-component fibers and the fine fibers of a composite media produced using the system of FIG. 12 taken at a magnification level xl ,000;
• FIG. 15(C) is a Scanning Electron Microscopic image showing bonding between bi-component fibers and the fine fibers of a composite media produced using the system of FIG. 12 taken at a magnification level x2,000;
• FIG. 15(D) is a Scanning Electron Microscopic image showing bonding between bi-component fibers and the fine fibers of a composite media produced using the system of FIG. 12 at a magnification level ⁇ , ⁇ ;
• FIG. 16 is a schematic cross-sectional view (e.g. relative illustrated thickness not to scale) of a coalescing filter element including an expanded nanofiber composite media and a compressed nanofiber composite coalescing media according to an embodiment of the present invention.
• substrate is meant to be broad in nature and meant to include any structure upon which fine fibers are carried or deposited.
• Substrate may include conventional formed filter medias such as scrims and the like that may be unwound from media rolls. Such filter medias have a fiber
• Substrate may also include looser fiber
• a "scrim” used as herein refers to woven or non-woven fiber entanglement, wherein the fibers are bonded and compressed into a planar formed media.
• FIG. 1 is a schematic cross-sectional view of a filter media 100 according to an embodiment of the present invention. It is schematic in the sense that in reality the fine fiber layer has virtually no thickness, but for illustration and understanding, thickness is illustrated in FIG. 1 and other schematic illustrations.
• the filter media 100 is configured to coalesce water in hydrocarbon fuels, such as diesel fuel, jet fuel, and gasoline.
• the filter media 100 can also capture solids in a hydrocarbon fuel stream.
• the filter media 100 is also referred to as a coalescer, a coalescing media, a coalescing filter media, or other similar terms in the present application.
• the filter media 100 includes at least two different fibers, for example, electrospun nanofibers and a substrate of coarser fibers carrying the nano fibers.
• the filter media 100 is also referred to as a composite filter media, a composite media, or other like terms in this application.
• the filter media 100 is particularly well suited for coalescing applications, the filter media 100 may be used in other filtration applications.
• the filter media 100 comprises 10 layers of substrate 102, 104, 106, 108, 110, 112, 114, 116, 118, 120, each of which carrying fine fibers 124, 126, 128, 130, 132, 134, 136, 138, 140, 142, and a media 122 on top of the fine fibers 142.
• the substrate, 102, 104, 106, 108, 110, 112, 114, 116, 118, 120 and the media 122 are formed of fibers having an average fiber diameter typically larger than that of the fine fibers.
• the substrate layers 102, 104, 106, 108, 110, 112, 114, 116, 118, 120, the fine fibers 124, 126, 128, 130, 132, 134, 136, 138, 140, 142, and the media 122 are laminated and tightly compressed together to increase fiber surface area per volume to provide a sufficient fiber surface area for water emulsified in a hydrocarbon fuel, such as a diesel fuel, to coalesce.
• the fine fibers 124, 126, 128, 130, 132, 134, 136, 138, 140, 142 are formed of a hydrophilic material, for example nylon-6, to attract water and to enhance formation and growth of water droplets, facilitating separation of water from a hydrocarbon fuel stream.
• this media layer is optional, and thus, the filter media 100 according to other embodiments may not include this media layer 122.
• the filter media of FIG. 1 may be formed using the process shown in FIG. 2.
• FIG. 2 illustrates the filter media 100 in a pre-compressed state 144 and a compressed state 146.
• the filter media 100 in the pre-compressed state 144 has an initial thickness t' (also referred herein as an original thickness.)
• the filter media 100 in the pre-compressed state 144 is compressed into the compressed state 146 using a set of calendering rollers 148 (or progressive sets of rolls), 150, wherein the initial thickness t' is reduced to a final thickness t.
• the filter media 100 in the pre-compressed state 144 is heated before compressing.
• fibers of the substrate relax and reorient to increase an average distance between the fibers during heating (such as a scrim that has been at least partially compressed during the scrim production process.)
• the substrate layers expand and loft, wherein the thickness of each of the substrate layer increases.
• the fine fibers which are carried by these fibers move and reorient with the fibers.
• fine fibers are extended, pushed and pulled with the larger fibers.
• the initial thickness t' of the pre-compressed state 144 can increase by at least 1.5 times, 2 times, 3 times or even more via heating.
• the final thickness t of the filter media 100 after subsequent compression of the lofted filter media 100 can be either less than, or equal to, or greater than the initial thickness t', depending on the amount of expansion during heating and the amount of reduction during compression.
• the filter media 100 in the pre-compressed state 144 can be heated and compressed simultaneously via a set of heated calendering rollers. In such
• the compressed filter media 100 having the final thickness t can be heated post compression, wherein the thickness t' may be increased.
• the filter media 100 can be heated more than once. For example, the filter media 100 can be heated before compression, then heated again during compression.
• the final thickness t can be between about 50% and 300% of the initial thickness t', preferably between about 70% and 200% of the initial thickness t', and more preferably between 80% and 150% of the initial thickness t'.
• the filter media 100 in the pre-compressed state 144 is pressed down to the final compressed state 146, the fine fibers 124, 126, 128, 130, 132, 134, 136, 138, 140, 142 become more integrated with the coarse fibers of the adjacent substrate layers 102, 104, 106, 108, 110, 112, 114, 116, 118, 120 and form 3 dimensional fine fiber matrix within the filter media 100.
• the filter media 100 in the compressed state 146 has characteristics sufficient for a coalescing media.
• the filter media 100 in this embodiment includes 10 layers of substrate carrying fine fibers, other embodiments can include more or less substrate layers carrying fine fibers.
• the substrate layers 102, 104, 106, 108, 110, 112, 114, 116, 118, 120 can be formed of any suitable porous material.
• Each of the substrate layer can be formed of a same type of porous material or different types of porous material.
• each layer of the substrate 102, 104, 106, 108, 110, 112, 114, 116, 118, 120 comprises a formed filter media.
• the formed filter media comprises fibers that are bonded together.
• the fibers of the formed filter media may be bonded together by solvent bonding, thermal bonding, and/or pressure bonding.
• the formed filter media can carry fine fibers and provide a structural support.
• the formed filter media typically can be independently used as a filter media, such as an air filter media, without being laminated or supported by other media or structure.
• the formed filter media is also referred to as a substrate filter media, a filter media substrate, a substrate, a filter media, or other like terms in the present application.
• the substrate may comprise one or more webs of fibers which are loosely tangled together in a highly fluffed thick state and may not be bonded together as in the case of a formed filter media.
• the web of coarse fibers can easily be pulled apart with very little manual effort and has little structural integrity such that it is not considered a formed filter media in the conventional sense.
• the fibers of the web of fibers typically have a larger average fiber diameter than an average fiber diameter of the fine fibers.
• the web of fibers is also referred to as a web of coarse fibers or other like terms in this application.
• a composite filter media including fine fibers integrated with such web of coarse fibers is described in Integrated Nanofiber Filter Media, US Patent Application Publication No. 2009/0266759, which is assigned to the assignee of the present application, the entire disclosures of which are incorporated herein by reference thereto.
• the substrate 102, 104, 106, 108, 110, 112, 114, 116, 118, 120 is a multi-component filter media.
• multi-component filter media can comprise fibers formed of a first material and fibers formed of a second material, wherein the first material and the second material are different materials.
• a multi-component filter media can be formed of fibers including at least two different materials, such as fibers including a core formed of the first material and a sheath formed of the second material, as described in detail below.
• a multi- component filter media including two different materials is refer to herein as "bi-component filter media", "bi-component media”, and like terms.
• each of the substrate layers 102, 104, 106, 108, 110, 112, 114, 116, 118, 120 comprises a scrim formed of bi-component fibers including two different materials having different melting points.
• a composite filter media comprising fine fibers and a substrate formed of such multi-component fibers are described in Multi-Component Filter Media with Nano fiber Attachment, PCT Patent Application No. PCT/US09/50392, which is assigned to the assignee of the present application, the entire disclosure of which are incorporated herein by reference thereto.
• one component of the bi-component fibers of the scrim has a lower melting point than the other component.
• the low melt component can be any suitable polymer such as polypropylene, polyethylene, or polyester.
• the other component may be a polymer having a higher melting point than the low melt component, or other suitable fiber materials such as glass and/or cellulose.
• the bi-component fibers are bonded together and/or compressed together to form a scrim or a substrate filter media having a certain thickness.
• the bi-component fibers of the scrim used as the substrate 102, 104, 106, 108, 110, 112, 114, 116, 118, 120 can include a high melt polymer component and a low melt polymer component.
• the bi-component may comprise a high-melt polyester and a low-melt polyester, in which one has a higher melting temperature than the other.
• FIG. 3 schematically illustrates a bi-component fiber 22 according to one embodiment. As shown, the bi-component 22 is a concentric sheath/core type, wherein a core 24 is formed of a high melt polymeric component and a sheath 26 is formed of a low melt polymeric component.
• the high melt polymer component is formed of a polymer having a higher melting temperature than the low melt polymer component.
• Suitable high melt polymers include, but are not limited to, polyester and polyamide.
• Suitable low polymers include polypropylene, polyethylene, co-polyester, or any other suitable polymers having a lower melting temperature than the selected high melt polymer.
• bi-component fibers may be formed of a polyester core and a polypropylene sheath. In this embodiment, the bi- component fibers are formed of two different types of polyesters, one having a higher melting point than the other.
• bi-component fibers may be used to form the substrate 102, 104, 106, 108, 110, 112, 114, 116, 118, 120 in other embodiments.
• FIGS. 4-10 Some examples of different types of bi-component fibers are schematically illustrated in FIGS. 4-10.
• the different shrinkage rates of the two polymer components can cause the fiber to curl into a helix when heated. This allows an otherwise flat fiber to develop crimp and bulk, and can result in different fiber reorientation, expansion and/or undulation of surface under heat.
• FIG. 5 schematically illustrates a side -by-side type bi-component fiber 34 including a first polymer component 36 and a second polymer component 38.
• the first polymer component may be a higher or lower melt polymer than the second polymer component.
• a pie wedge type bi-component fiber 40 is schematically illustrated in FIG. 6.
• the pie wedge fiber 40 comprises a plurality of adjacent wedges formed of a first polymer component 42 and a second polymer component 44.
• Each of the first polymer component 42 has a second polymer component 44 on either side.
• the first polymer component 42 may be a higher or lower melt polymer than the second polymer component 44.
• These fibers are designed to be split into the component wedges by mechanical agitation (typically hydroentangling), yielding microfibers of 0.1 to 0.2 denier in the filter media.
• FIG. 7 is a schematic illustration of a hollow pie wedge type bi-component fiber 46 comprising first polymer wedges 48 and second polymer wedges 50.
• the first polymer wedges 48 may be formed of a higher or lower melt polymer than the second polymer wedges 50.
• the hollow pie wedge fiber 46 is similar to the pie wedge fiber 40 but with a hollow center 52 core that prevents the inner tips of the wedges from joining, thus making splitting easier.
• FIG. 8 is a schematic illustration of a islands/sea type bi-component fiber 54. This fiber is also known as the "pepperoni pizza" configuration where a first polymer component 56 is the pepperoni and a second polymer component 58 is the cheese.
• the first polymer component 56 is formed of a higher melt polymer than the second polymer component 58, or the second polymer component 58 is formed of a soluble polymer.
• this fiber allows the placement of many fine strands of high melt polymer 56 within a matrix of low melt or soluble polymer 58 that is subsequently melted or dissolved away. This allows the production of a media made of fine microfiber because the fibers are easier to process in the "pizza" form rather than as individual “pepperonis.” Staple fibers can be made of 37 pepperonis on each pizza, producing fibers about 0.04 denier (about 2 microns diameter), or even finer.
• the bi-component fibers may be formed into different shapes. For example, some bi-component fibers may not have a cylindrical shape with a circular cross section as the bi-component fibers described above.
• FIGS. 9 and 10 illustrate some examples of bi- component fibers with irregular shapes. Although, these fibers do not have a circular cross section, each has a diameter in context of the present invention. The diameter of the fibers having a non-circular cross section is measured from the outer perimeter of the fiber.
• FIG. 9 is a schematic illustration of a trilobal type bi-component fibers 60, 62. Each of the trilobal fibers 60, 62 comprises a first polymer component 64, 66 and a second polymer component 68, 70. Each of the trilobal fibers 60, 62 are measured by its diameter 72, 74.
• the first polymer component 64, 66 is formed of a higher melt or lower melt polymer than the second polymer component 68, 70.
• FIG. 10 is a schematic illustration of a tipped type bi-component fibers 78, 80.
• the fiber 78 is a tipped trilobal bi-component fiber with a first polymer center 82 and second polymer tips 84.
• the fiber 80 is a tipped cross bi-component fiber with a first polymer center 86 and second polymer tips 88.
• the first polymer center 82, 86 is formed of a higher melt polymer than the second polymer tips 84, 88.
• the fibers of the substrate 102, 104, 106, 108, 110, 112, 114, 116, 118, 120 are formed to have a larger average fiber diameter than that of the fine fibers 124, 126, 128, 130, 132, 134, 136, 138, 140, 142.
• the fibers of the substrate 102, 104, 106, 108, 110, 112, 114, 116, 118, 120 can have an average fiber diameter of greater than about 1 micron, preferably greater than about 2 micron, and more preferably, greater than 5 micron.
• an average diameter of the bi-component fibers of the substrate 102, 104, 106, 108, 110, 112, 114, 116, 118, 120 are between about 1 micron and about 40 micron.
• the coarse fibers are compressed and/or heated, for example via a set of calendering rollers and/or an oven, to form the substrate 102, 104, 106, 108, 110, 112, 114, 116, 118, 120, wherein any of the substrate layers has a thickness between about 0.05 and 1.0 mm, preferably between about 0.1 and 0.5 mm.
• Such substrate can provide a structural support necessary for the fine fibers.
• Bi-component scrims of various thicknesses suitable for use as any of the substrate layers 102, 104, 106, 108, 110, 112, 114, 116, 118, 120 are commercially available through various suppliers, such as HDK Industries, Inc. of
• the substrate can be selected from such off the shelf bi-component medias.
• each layer of the substrate 102, 104, 106, 108, 110, 112, 114, 116, 118, 120 and the media 122 comprise a scrim formed of bi-component staple fibers having a high melt polyester core and a low melt polyester sheath.
• the bi-component staple fibers are compressed together to form the scrim, wherein the bi-component staple fibers are bonded together chemically, mechanically and/or thermally.
• the bi- component staple fibers are heated to or near the melting temperature of the low melt polyester and compressed together, wherein the sheath formed of the low melt polyester melts or softens and acts as a bonding agent to bond fibers together.
• the fine fibers 124, 126, 128, 130, 132, 134, 136, 138, 140, 142 can be deposited directly on the corresponding substrate 102, 104, 106, 108, 110, 112, 114, 116, 118, 120 as they are formed.
• the fine fibers 124, 126, 128, 130, 132, 134, 136, 138, 140, 142 may be separately prepared as a web of fine fibers, then laminated with the substrate 102, 104, 106, 108, 110, 112, 114, 116, 118, 120.
• the fine fibers 124, 126, 128, 130, 132, 134, 136, 138, 140, 142 may comprise fibers having various fiber diameters, preferably, the fine fibers 124, 126, 128, 130, 132, 134, 136, 138, 140, 142 are nanofibers having very fine fiber diameter.
• Such fine fibers 124, 126, 128, 130, 132, 134, 136, 138, 140, 142 can be formed by electrospinning or other suitable processes.
• the fine fibers 124, 126, 128, 130, 132, 134, 136, 138, 140, 142 are examples of the fine fibers 124, 126, 128, 130, 132, 134, 136, 138, 140, 142.
• electrospun nanofibers having an average fiber diameter less than about 1 micron, preferably less than 0.5 micron, and more preferably between 0.01 and 0.3 microns.
• Such small diameter fine fibers can pack more fibers together in a given volume to provide an increased fiber surface area in a coalescing filter media for formation of water droplets.
• the fine fibers 124, 126, 128, 130, 132, 134, 136, 138, 140, 142 may be formed by various suitable polymeric materials.
• the fine fibers 124, 126, 128, 130, 132, 134, 136, 138, 140, 142 are typically formed of a material having a higher melt temperature than at least the low-melt component of the bi-component fibers of the substrate.
• the fine fibers are formed of a hydrophilic material such as polyamides.
• hydrophilic polymers include, but not limited to, poly(acrylic acid), polyalkylene glycols, polyvinyl alcohol, polyvinyl acetate, polyalkylene glycols, copolymers of methylvinyl ether and maleic acid, maleic anhydride polymers, polylkylene oxides, poly(meth)acrylamides, hydrophilic polyurethanes, polyethyleneimines, methyl cellulose, hydroxylmethyl cellulose, hydroxyethyl cellulose, polyvinylsulfonic acid, poly(saccharides) such as chitosan and many other polymers or copolymers with enough -OH, -COOH, and/or -NH2 groups.
• poly(acrylic acid) polyalkylene glycols
• polyvinyl alcohol polyvinyl acetate
• polyalkylene glycols copolymers of methylvinyl ether and maleic acid
• maleic anhydride polymers polylkylene oxides
• the fine fibers 124, 126, 128, 130, 132, 134, 136, 138, 140, 142 are formed of nylon-6 (polyamide-6, also referred to as "PA-6" herein) via
• the electrospun fine fibers 124, 126, 128, 130, 132, 134, 136, 138, 140, 142 are deposited directly on the substrate 102, 104, 106, 108, 110, 112, 114, 116, 118, 120.
• the fine fibers 124 are generated electrostatically from a solution containing nylon-6 and deposited on a surface of the substrate 102.
• the fine fibers 126 can be similarly generated and deposited on the substrate layer 104, and so on.
• the substrate layers 102, 104, 106, 108, 110, 112, 114, 116, 118, 120 coated with the electrospun nanofibers 124, 126, 128, 130, 132, 134, 136, 138, 140, 142 are then laminated together with the media 122, such that each layer of the fine fibers 124, 126, 128, 130, 132, 134, 136, 138, 140, 142 is sandwiched between the adjacent substrate 102, 104, 106, 108, 110, 112, 114, 116, 118, 120 and/or the media 122 to create the filter media 100 in the pre- compressed state 144 as shown in FIG. 2.
• the filter media 100 in the pre-compressed state 144 is then compressed to form the coalescing filter media 100 in its final compressed state 146 as shown in FIGS. 1 and 2.
• the coalescing filter media 100 is heated before, during, and/or after the compression.
• the filter media 100 in the pre-compressed state 144 is heated prior to passing through the set of calendering rollers 148, 150.
• the set of calendering rollers 148, 150 can be heated to further heat the filter media 100 during the compression.
• the bonding between the fine fibers 124, 126, 128, 130, 132, 134, 136, 138, 140, 142 and the adjacent coarser fibers of substrate 102, 104, 106, 108, 110, 112, 114, 116, 118, 120 and/or media 122 may involve solvent bonding, pressure bonding, and/or thermal bonding.
• the fine fibers are electrostatically generated from a polymer solution containing a solvent, the solvent remaining on the surface of the fine fibers can effectuate a solvent bonding as the fiber fibers come in contact with the coarse fibers of the substrate.
• the low melt component of the bi-component fibers of the substrate can be used to enhance bonding between the fine fibers and the adjacent coarse fibers of the substrate.
• the filter media 100 is heated to or near the melting point of the low melt component and compressed, wherein the low melt component of the bi- component coarse fibers melts or softens, which allows the adjacent fine fibers to embed into the low melt component as they are compressed together, thereby enhancing the bonding between the coarse fibers and the fine fibers (via pressure bonding and thermal bonding.)
• the coalescing filter media 500 includes 10 layers of substrate 502, 504, 506, 508, 510, 512, 514, 516, 518, 520, each of which carrying fine fibers 524, 526, 528, 530, 532, 534, 536, 538, 540, 542, and a media 522, all of which are tightly compressed together similar to the filter media 100.
• the coalescing filter media 500 includes a porous layer 544 on the downstream surface 548.
• the porous layer 544 is also referred herein as a "drainage layer".
• the filter media 500 may not include the media layer 522 and the porous layer 544.
• the media 522 and each layer of the substrate 502, 504, 506, 508, 510, 512, 514, 516, 518, 520 are formed of a bi-component fiber scrim having an average fiber diameter between about 1 and 40 microns and a base weight between about 0.5 and 15 oz/yd 2 .
• the bi-component fibers comprise a high-melt polyester core and a low melt polyester sheath.
• the fine fibers 524, 526, 528, 530, 532, 534, 536, 538, 540, 542 are electrospun nanofibers formed of nylon-6.
• the fine fibers have an average fiber diameter between about 0.01 and 0.5 microns, wherein each layer of the fine fibers 524, 526, 528, 530, 532, 534, 536, 538, 540, 542 has fine fiber coverage between about 0.075 g/m 2 and .225 g/m 2 , providing total fine fiber coverage between 0.75 g/m 2 and 2.25 g/m 2 .
• the porous layer 544 (also referred herein as a drainage layer) can be formed of various materials such as a cellulous material or fiber glass.
• the porous layer 544 is formed of a fiber glass, and has a pore size greater than or equal the bi- component fiber scrim.
• the porous layer 544 allows continual growth of water droplet that are coalesced through the compacted substrate layers and fine fiber layers, and allows the water droplets to pass through the porous layer 544 for subsequent collection of water droplets. Further, the porous layer 544 can provide additional structural support for the compacted substrate and fine fiber layers.
• the media 522, the substrate layers 502, 504, 506, 508, 510, 512, 514, 516, 518, 520, the fine fibers 524, 526, 528, 530, 532, 534, 536, 538, 540, 542, and the porous layer 544 are laminated and compressed together to form the tightly packed coalescing filter media 500 having a total thickness between about 3/16" to 1 ⁇ 2".
• the drainage layer 544 is formed of a siliconized cellulous material.
• the drainage layer 544 is not continuously bonded to the substrate layer 502, but may be partially secured to the substrate layer 502 to prevent sliding movements when the coalescing filter media 500 is subsequently pleated or formed into various filter elements.
• the compacted substrate and fine fiber layers coalesce water droplets into a size sufficient to be captured by the drainage layer 544 that is formed of the hydrophobic siliconized cellulous material.
• the hydrophobic drainage layer 544 acts as a water barrier preventing the water droplets from flowing through the pore of the hydrophobic drainage layer 544. Instead, the water droplets flow along the hydrophobic inner surface of the drainage layer 544 and run down between the substrate layer 502 and the drainage layer 544. The water droplets are then collected off line, allowing only fuel to enter the engine.
• a hydrocarbon fuel stream enters the coalescing filter media 500 from the upstream surface 546, flows through the layers of substrate and fine fibers, and exits through the porous layer 544 on the downstream surface 548.
• water emulsified in the hydrocarbon fuel stream coalesces due to the large fiber surface area provides by the fine fibers.
• the hydrophilic fine fibers attract water, enhancing formation of water droplets.
• the coalesced water droplets further grow in size as they pass through large pores of the porous layer 544 and are separated from the hydrocarbon fuel. Further, solids and/or contaminants in the hydrocarbon fuel system can be captured within pores of the coalescing filter media 500, thereby providing added filtration capacity.
• the substrate layers 502, 504, 506, 508, 510, 512, 514, 516, 518, 520 comprise different medias.
• some of the substrate layers may be formed of a thicker scrim or filter media than other layers, or may have different pore sizes than other layers.
• the fine fiber layers 524, 526, 528, 530, 532, 534, 536, 538, 540, 542 may have a same fine fiber coverage or different fine fiber coverage.
• some of the fine fiber layers can have a fine fiber coverage of about 0.08 g/m 2
• other fine fiber layers have a fine fiber coverage of about 0.2 g/m 2 .
• the fine fiber coverage of each layer can be configured according to characteristics of a hydrocarbon fuel stream and water content to optimize the coalescing process.
• FIG. 12 schematically illustrates a representative process of making a coalescing filter media according to a processing embodiment of the present invention.
• this embodiment includes downstream process steps for making the coalescing filter media 500 of FIG. 11, the process can produce filter medias according to other embodiments of the present invention with minor modifications.
• a system 200 shown in FIG. 12 includes an upstream system 201 for making a composite media including a substrate and fine fibers deposited thereon, and a downstream system 203 for laminating and compressing multiple layers of composite media and other additional layers to make a coalescing filter media.
• the upstream system 201 includes an unwinding station 202, an electrospinning station 204, an optional oven 206, an optional set of calendering rollers 207 and a rewinding station 208.
• a roll of scrim 210 which is used here as a substrate layer, is unwound from the unwinding station 202.
• the scrim 212 unwound from the roll of scrim 210 travels in a machine direction 214 toward the electrospinning station 204.
• fine fibers 216 are formed and deposited on one surface of the scrim 212 to form a composite media 218 comprising the scrim carrying the fine fibers 216.
• the composite media 218 may be heated and compressed in the optional oven 206 and the optional set of calendering rollers 207 before being wound into a roll of composite media 230 on the rewound station 208.
• the scrim may be formed in an upstream process of the system 200 (either part of a continuous line process or interrupted line process) or may be purchased in a roll form from a supplier such as HDK or other suitable media supplier such as H&V or Ahlstrom or the like.
• the scrim can be formed of various suitable materials, such as bi-component fibers of FIGS. 3-10 as discussed above.
• the scrim can be formed of high melt polyester core/low melt polyester sheath bi-component staple fibers, which are compressed and/or heated to form the roll of scrim 210 having a desired thickness and solidity.
• the substrate layer may be other single component media that may be compressed and held in place via a solvent bond, heat bond or the like.
• the concentric sheath/core type bi- component fibers may be coextruded using a high melt polyester as the core and a low melt polyester as the sheath. Such bi-component fibers can then be used to form a scrim or a filter media.
• the bi-component fibers are used as staple fibers to form a multi-component filter media or a scrim via conventional dry laying or air laying process. The staple fibers used in this process are relatively short and discontinuous but long enough to be handled by conventional equipment.
• Bales of the bi-component fibers can be fed through a chute feed and separated into individual fibers in a carding device, which are then air laid into a web of fibers (which itself for purposes of the present disclosure may be used as a substrate.)
• the web of fibers is then compressed using a set of calendering rollers to form the roll of scrim 210 (which can also be used as a substrate.)
• the web of the fibers may optionally be heated before entering the set of calendering rollers.
• the scrim 210 of this embodiment comprises bi-component fibers, including a high melt component and a low melt component, it is also referred to as a bi-component filter media.
• the web of fibers are folded before being calendered to form a thicker bi- component filter media.
• a web comprising high melt polymer fibers such as polyester fibers and a web comprising low melt polymer fibers such as polypropylene fibers can be formed, separated and laminated together to form the roll of bi-component filter media or scrim.
• the fine fibers 216 are deposited on the low melt side of the scrim 212.
• the low melt web is substantially thinner than the high melt web, such that the low melt component does not clog the surface of the high melt web when heated and melted.
• the bi-component fiber scrim can be formed via a melt blowing process.
• molten polyester and molten polypropylene can be extruded and drawn with heated, high velocity air to form coarse fibers.
• the fibers can be collected as a web on a moving screen to form a bi-component scrim 210.
• the multi-component fiber filter media or scrim may also be spun-bounded using at least two different polymeric materials.
• a molten polymeric material passes through a plurality of extrusion orifices to form a multifilamentary spinline.
• the multifilamentary spinline is drawn in order to increase its tenacity and passed through a quench zone wherein solidification occurs which is collected on a support such as a moving screen.
• the spun-bounding process is similar to the melt blowing process, but melt blown fibers are usually finer than spun-bounded fibers.
• the multi-component filter media is wet-laid.
• high melt fibers and low melt fibers are dispersed on a conveying belt, and the fibers are spread in a uniform web while still wet.
• Wet-laid operations typically use 1 ⁇ 4" to 3 ⁇ 4" long fibers, but sometimes longer if the fiber is stiff or thick.
• the above discussed fibers are compressed to form a scrim 210 or a filter media having a desired thickness.
• the scrim 212 enters the electrospinning station 204, wherein the fine fibers 216 are formed and deposited on one surface of the scrim 212.
• the fine fibers 216 are electrospun from eletrospinning cells 222 and deposited on the web of scrim 212.
• the electrospinning process of the system 200 can be substantially similar to the electrospinning process disclosed in Fine Fibers Under 100 Nanometers, And Methods, U.S. Patent Application Publication No. U.S.
• nozzle banks or other electrospinning equipment can be utilized to form the fine fibers.
• Such alternative electrospinning devices or rerouting of chain electrodes of the cells 222 can permit the fibers to be deposited in any orientation desired (e.g. upwardly is shown although fibers can also be spun downwardly, horizontally or diagonally onto a conveyor carrying coarser fibers).
• the electrospinning process produces synthetic fibers of small diameter, which are also known as nano fibers.
• the basic process of electrostatic spinning involves the introduction or electrostatic charge to a stream of polymer melt or solution in the presence of a strong electric field, such as a high voltage gradient.
• Introduction of electrostatic charge to polymeric fluid in the electrospinning cells 222 results in formation of a jet of charged fluid.
• the charged jet accelerates and thins in the electrostatic field, attracted toward a ground collector. In such process, viscoelastic forces of polymeric fiuids stabilize the jet, forming small diameter filaments.
• An average diameter of fibers may be controlled by the design of eletrospinning cells 222 and formulation of polymeric solutions.
• the polymeric solutions used to form the fine fibers can comprise various polymeric materials and solvents.
• polymeric materials include polyvinyl chloride (PVC), polyolefin, polyacetal, polyester, cellulous ether, polyalkylene sulfide, polyarylene oxide, polysulfone, modified polysulfone polymers and polyvinyl alcohol, polyamide, polystyrene, polyacrylonitrile, polyvinylidene chloride, polymethyl
• Solvents for making polymeric solution for electrostatic spinning may include acetic acid, formic acid, m-cresol, tri-fluoro ethanol, hexafiuoro isopropanol chlorinated solvents, alcohols, water, ethanol, isopropanol, acetone, and N-methyl pyrrolidone, and methanol.
• the solvent and the polymer can be matched for appropriated use based on sufficient solubility of the polymer in a given solvent and/or solvent mixture (both of which may be referred to as "solvent".)
• formic acid may be chosen for nylon-6. Reference can be had to the aforementioned patents for further details on electrospinning of fine fibers.
• an electrostatic field is generated between electrodes in the electrospinning cells 222 and a vacuum collector conveyor 224, provided by a high voltage supply generating a high voltage differential.
• a vacuum collector conveyor 224 provides a high voltage supply generating a high voltage differential.
• the vacuum collector conveyor 224 also holds and transfers the scrim 212 in the machine direction 214. As configured, the scrim 212 is positioned between the electrospinning cells 222 and the vacuum collector conveyor 224, such that the fine fibers 216 are deposited on the scrim 212.
• the multi-component scrim 212 is positioned between the electrospinning cells 222 and the vacuum collector conveyor 224, such that the low melt component surface of the multi-component scrim faces the electrospinning cells 222.
• the electrospinning cells 222 contain a polymeric solution comprising polyamide-6 (PA-6) and a suitable solvent consisting of 2/3 acetic acid and 1/3 formic acid. In such a solvent, both acetic acid and formic acid act as a dissolving agent to dissolve PA-6, and acetic acid controls conductivity and surface tension of the polymeric solution.
• the electrospinning cells 222 generate fine fibers formed of PA-6, which are deposited onto a surface of the scrim 212. As the fine fibers 216 are deposited on the surface of the scrim 212, some fine fibers 216 entangle with coarse fibers of the scrim proximate the surface facing the electrospinning cells 222.
• the bonding between bi-component fibers of the scrim 212 and the fine fibers 216 may be enhanced via thermal bonding and pressure bonding by the optional oven 206 and the optional set of calendering rollers 207. As the composite media 218 is heated in the oven 206, the low melt polymer component of the bi-component fibers softens or melts and allowing the fine fibers 216 to embed into the low melt polymer component.
• the composite filter media 218 is heated to at least above the glass transition temperature of the low melt component, and more preferably to or near the melting temperature of the low melt component.
• the composite media 218 is heated to or near the melt point of low melt polyester, such that the outer low melt polyester layer of the bi-component fibers melts and bonds with the fine fibers 216 formed of PA-6.
• PA-6 fine fibers 216 and the high melt polyester core of the bi- component fibers do not melt, since PA-6 and the high melt polyester have a significantly higher melting temperature than that of the low melt polyester.
• the low melt polyester which has the lowest melting temperature, melts or softens, and adjacent PA-6 fine fibers 216 are embedded in the softened or melted low melt polyester, thereby bonding the fine fibers 216 and the scrim 212 together.
• the low melt polyester acts as a bonding agent between the bi-component fiber scrim 212 and the fine fibers 216.
• the bonding between the fine fibers 216 and the scrim 212 can further be enhanced through pressure bonding via the set of calendering rollers 207.
• the fine fibers 216 and the scrim 212 are compressed together, wherein the fine fibers are further embedded into the fibers of the scrim 212. Further, the compression reduces voids in the composite media to form a composite media 220 with an increased solidity.
• FIGS. 15(A)- 15(D) are Scanning Electron Microscopic (SEM) images of the bi- component fibers of the scrim 212 and the fine fibers 216 proximate the surface of the scrim 212 taken at various magnification levels.
• SEM Scanning Electron Microscopic
• the roll of composite media 230 including the bi-component scrim 212 and the fine fibers 216 is laminated with other composite medias 232, 234, 236, 238, 240, 242, 244, 246, 248, and a media 250 in the downstream system 203.
• Each of the composite media rolls 230, 232, 234, 236, 238, 240, 242, 244, 246, 248, and a roll of the media 250 are unwound from unwind stations 252, 254, 256, 258, 260, 262, 264, 266, 268, 270, 272, and laminated together by a set of rollers 274.
• the set of rollers may be a calendering rollers to apply a significant pressure to laminate and significantly reduce a thickness of the layers of composite medias.
• the set of rollers 274 may apply a small pressure to laminate and reduce the thickness of the laminated layers just enough to fit through an oven 276.
• the laminated layers 280 is heated in the oven 276 and compressed via a set of calendering rollers, wherein the laminated layers 280 is compressed together into a compressed state having a desired thickness and solidity.
• each roll of the composite media 232, 234, 236, 238, 240, 242, 244, 246, 248 is prepared similarly as the roll of the composite media 230. Therefore, each of the roll of the composite media 232, 234, 236, 238, 240, 242, 244, 246, 248 includes a substrate formed of a bi-component fiber scrim 284, 286, 288, 290, 292, 294, 296, 298, 300, and electrospun nanofibers 302, 304, 306, 308, 310, 312, 314, 316, 318, carried by the bi-component fiber scrim 284, 286, 288, 290, 292, 294, 296, 298, 300.
• each of the substrates 212, 284, 286, 288, 290, 292, 294, 296, 298, 300 and the media 250 are formed of a same bi-component fiber scrim having a thickness between about 0.05 mm and 1.0 mm.
• Each layer of the fine fibers 216, 302, 304, 306, 308, 310, 312, 314, 316, 318, is formed by electrospinning PA-6 polymer solution to produce a fine fiber coverage between about 0.075 g/m 2 and .225 g/m 2 .
• the substrates may be formed of different types of filter media or scrim, and each of the fine fibers layer may have different fine fiber coverage.
• the composite media 280 is heated in the oven 276 to or near a melting temperature of the low melt polyester component of the bi-component fiber scrim. During heating the substrates can relax and expand in thicknesses. Thus, the lofted composite media 281 can have a thickness that is at least 1.5 times, 2 times, 3 times or even greater than the thickness of the composite media 280 before being heated in the oven 276. The lofted composite media 281 is then compressed via the set of calendering rollers 282 into the compressed state 320.
• the composite media is compressed, such that the thickness of the composite media 280 is reduced between about 50% and 300%, preferably between about 70%) and 200%>, and more preferably between about 80%> and 150% of the original thickness of the composite media 280 prior to heating ((total thickness of 10 scrim layers carrying 10 fine fiber layers + thickness of media - thickness of the composite media in the compressed state 320)/(total thickness of 10 scrim layers carrying 10 fine fiber layers + thickness of media).)
• the thickness reduction will depend on the amount of lofting during heating. Thus, when the lofting from heating is large, the final thickness of the composite media after compression may be greater than the initial thickness of the composite media before heating.
• the composite media in the compressed state 320 is then laminated with a drainage layer 322 and wound into a roll of coalescing media 324.
• the rolls of the composite media 230, 232, 234, 236, 238, 240, 242, 244, 246, 248. and the media 250 are laminated together, such that each of the fine fiber layers 216, 302, 304, 306, 308, 310, 312, 314, 316, 318 is sandwiched between adjacent substrate layer and/or media.
• the composite media layers may be laminated such that some of the fine fiber layers face each other to form fine fiber to fine fiber or substrate to substrate bonding within the final composite media 320.
• FIG. 13 schematically illustrates a system and a process of making a coalescing filter media according to a different embodiment of the present invention.
• a system 400 generally includes an unwinding station 402, an electrospinning station 404, a folding station 406, a set of rollers 408, an oven 410, and a set of calendering rollers 412 and a rewinding station 414.
• a roll of substrate 416 is unwound from the unwinding station 402 and transferred to the electrospinning station 404, wherein fine fibers are formed and deposited on a surface of the substrate 416.
• the electrospinning station 404 and the process are similar to the electrospinning station 204 and the process described above.
• the substrate 416 is a scrim formed of bi-component fibers including a high melt polyester core and a low melt polyester sheath.
• the fine fibers 418 are formed of PA-6.
• the composite media 420 comprising the substrate 416 and fine fibers 418 is folded in the folding station 406.
• the composite media 420 can be folded to 2-20 folds thick depending on desired characteristics of the final coalescing media. As shown, the folding creates fine fiber to fine fiber laminated surfaces and substrate to substrate laminated surfaces.
• the folding station 406 in this embodiment is shown as folding the composite media 420 in a line direction, such that the folds are pointing toward the set of the rollers 408. However, in other embodiments, the composite media 402 may be folded such that the folds are pointing toward the electrospinning station 404, or folded in cross- line directions.
• the folded composite media 422 is then compressed to a thickness appropriate to pass through an oven 410.
• the low melt polyester sheath melts or softens to effectuate thermal bonding between layers.
• the composite media 424 passes through the set of calendering rollers 412.
• the calendering rollers 412 are spaced apart from each other according to a desired final thickness of the coalescing media.
• the composite media 424 is pressed down into a compressed state having a desired thickness as it passes through the set of calendering rollers 412.
• a media layer 426 and a porous layer 428 are laminated on each surface of the coalescing media 430 and wound into a roll in the rewinding station 414.
• a expanded cross sectional view of a coalescing filter media 432 including the coalescing media 430, the media layer 426, and the porous layer 428 is shown in FIG. 13.
• the coalescing media 430 includes multiple layers of substrate 416 and multiple layers of fine fibers 418 in a slanted orientation from the folding process.
• the media layer 426 can be formed of any suitable media, but in this embodiment, the media layer 426 is formed of the same bi-component fiber scrim used for the substrate 416.
• FIG. 14 shows yet a different embodiment of a system and a process of making a coalescing media.
• a system 600 is similar to the system 400 but the fine fibers in this embodiment are not deposited on a substrate. Rather, the fine fibers are formed and deposited onto a web of loosely entangled coarse fibers.
• the system 600 generally includes a chute 602, a carding device 603, an electrospinning station 604, a folding station 606, a set of rollers 608, an oven 610, and a set of calendering rollers 612 and a rewinding station 614.
• the web of coarse fibers 616 is formed from staple fibers using a dry laying or air laying process.
• the staple fibers of this embodiment are bi- component fibers comprising a high melt polyester core and a low-melt polyester sheath.
• the bi-component staple fibers are relatively short and discontinuous, but long enough to be handled by conventional equipment. Bales of staple fibers are fed through the chute feed 602.
• the bi-component staple fibers are separated into individual fibers and air laid to form the web of coarse fiber 616.
• the web of coarse fiber 616 can be loosely tangled together in a highly fluffed thick state and may not be bonded together.
• the web of coarse fiber 616 can be easily pulled apart with very little manual effort and has little structural integrity at this point such that it is not considered a filter media or substrate in the conventional sense.
• the web of coarse fiber 616 is transferred via a conveyor belt 617 toward the electrospinning station 604, wherein the fine fibers 618 are formed and deposited on a surface of the web of coarse fiber 616.
• the fibers 618 are integrated with the coarse fibers of the web of coarse fiber 616 much more than in the previous embodiment with the substrate 416, as the web of coarse fiber 616 are much more porous and less dense to allow deeper integration of the fine fibers 616.
• the web of coarse fiber 616 integrated with the fine fibers 618 are then folded into 10-30 folds in the folding station 606 and compressed via the set of rollers 608, which is heated in the oven 610 and compressed again via the set of calendering rollers 612 as it was with the system 400.
• the coalescing media 630 is then laminated with a media layer 626 and a porous layer 628 to from a coalescing filter media 632.
• the coarse bi-component fibers and the fine fibers of the coalescing media 630 of this embodiment are much more integrated.
• a cross sectional view of the coalescing media 630 does not show multiple layers, but rather appears more like a single integrated media 630.
• the coalescing media 630 has a sufficient fine fiber coverage and tightness to provide coalescing of water droplets from a fluid stream, such as a hydrocarbon fuel stream. Further, the coalescing filter media 632 is configured to remove water from such fluid stream.
• the coalescing media can be configured into various shapes and sizes for various applications.
• the coalescing media can be used in spin-on filter applications, large fuel filtration vessels, aviation filter systems, hydraulic filter elements, and bio-fuel systems.
• the coalescing media can be pleated or gathered into a fluted filter, a pleated filter, or other such typical filter element arrangements.
• the coalescing media works particularly well in coalescing applications, the coalescing media can also work effectively in other filtration applications such as filtering particulates from water.
• a typical coalescing filter element may include a pre-filter element and a coalescing element.
• the pre-filter media is typically a separate structure from the coalescing element and configured to filter out particulates from a fuel stream before the fuel stream enters the coalescing element to prevent particulates from blocking coalescing media pores.
• the coalescing filter element is constructed to include an expanded nanofiber composite media and a compressed coalescing filter media. Such coalescing filter element can filter particulates and coalesce water to eliminate the need of the pre-filter element.
• FIG. 16 shows a coalescing filter element 700 that includes an expanded nanofiber composite media 702, a compressed coalescing media 704, and a drainage layer 706.
• a fuel stream 708 enters the coalescing filter media 700 via the expanded nanofiber composite media 702 and flows though the compressed coalescing media 704 and exits out through the drainage layer 706.
• expanded nanofiber composite media is disclosed in US Provisional Patent Application No. 61/308,488, Expanded Composite Filter Media Including Nanofiber Matrix and Method, assigned to the assignee of the present application, entire disclosure of which is incorporated herein by reference thereto.
• the expanded nanofiber composite media 702 includes three layers of substrate 710, 712, 714, wherein the substrate layers 712 and 714 carry nano fibers 726, 728.
• the compressed nanofiber composite media 704 includes five layers of substrate 716, 718, 720, 722, 724, each of which carries nanofibers 730, 732, 734, 736, 738.
• Each of the substrate layers 710, 712, 714, 716, 718, 720, 722, 724 can be formed of a same or different porous material.
• each of the substrate layers are formed of a scrim comprising bi-component fibers as described above with regard to other embodiments of the coalescing media.
• the nanofibers 726, 728, 730, 732, 734, 736, 738 are deposited on the corresponding substrate layers via electrospinning similar to other embodiments described above.
• the expanded nanofiber composite media 702 is constructed by laminating the nanofiber 726, 728 deposited scrim layers 712, 714 with the scrim layer 710 and heating the laminated layers in an oven to reorient and loft fibers of scrim layers. As the scrim layers 710, 712, 714 reorient and loft, nanofibers 726, 728 also reorient and extend with the fibers of scrim layers. As a result, a volumetric coverage of nanofibers can increase (more volumetric coverage for a same basis weight application - as the expansion can open up and expand the nanofibers into a 3D matrix); a pressure drop can be reduced due to expansion; and/or a pressure drop increase with dust loading can be slowed. Thus, the expanded nanofiber composite media 702 layer can effectively filter out particulates in the fuel stream before it enters the subsequent compressed coalescing media layer 704.
• the compressed coalescing media 704 can be constructed similarly as the coalescing filter media 100 or 500 as described in detail above.
• the nanofiber deposited scrim layers are laminated, heated and compressed to form the compressed coalescing media to coalesce water in the fuel stream.
• the drainage layer 706 can be any porous media described above.
• the drainage layer 706 is a hydrophobic siliconized cellulous material. This drainage layer 706 is not continuously attached to the substrate layer 738, but secured to the substrate layer in several spots along sides. The hydrophobic drainage layer 706 prevents coalesced water droplets from passing through its pores.
• coalesced water droplets flow along the inner surface 725 of the drainage layer 706 and are collected. As such, only the fuel stream without the coalesced water droplets are allowed to pass through the drainage layer to enter an engine system.

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• Chemical & Material Sciences (AREA)
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• Chemical Kinetics & Catalysis (AREA)
• Nanotechnology (AREA)
• Crystallography & Structural Chemistry (AREA)
• Condensed Matter Physics & Semiconductors (AREA)
• General Physics & Mathematics (AREA)
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• Nonwoven Fabrics (AREA)
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