[go: up one dir, main page]

WO1999052619A1 - Composites ameliores de milieu de filtrage - Google Patents

Composites ameliores de milieu de filtrage Download PDF

Info

Publication number
WO1999052619A1
WO1999052619A1 PCT/US1998/007142 US9807142W WO9952619A1 WO 1999052619 A1 WO1999052619 A1 WO 1999052619A1 US 9807142 W US9807142 W US 9807142W WO 9952619 A1 WO9952619 A1 WO 9952619A1
Authority
WO
WIPO (PCT)
Prior art keywords
layer
media
fibers
composite
electret
Prior art date
Legal status (The legal status 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 status listed.)
Ceased
Application number
PCT/US1998/007142
Other languages
English (en)
Inventor
Scott H. Pryne
Ross D. West
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
All-Felt Filtration LLC
American Felt and Filter Co LLC
Original Assignee
All-Felt Filtration LLC
American Felt and Filter Co LLC
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
Application filed by All-Felt Filtration LLC, American Felt and Filter Co LLC filed Critical All-Felt Filtration LLC
Priority to PCT/US1998/007142 priority Critical patent/WO1999052619A1/fr
Publication of WO1999052619A1 publication Critical patent/WO1999052619A1/fr
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

Links

Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D39/00—Filtering material for liquid or gaseous fluids
    • B01D39/14—Other self-supporting filtering material ; Other filtering material
    • B01D39/16—Other self-supporting filtering material ; Other filtering material of organic material, e.g. synthetic fibres
    • B01D39/1607—Other self-supporting filtering material ; Other filtering material of organic material, e.g. synthetic fibres the material being fibrous
    • B01D39/1623—Other self-supporting filtering material ; Other filtering material of organic material, e.g. synthetic fibres the material being fibrous of synthetic origin
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2201/00—Details relating to filtering apparatus
    • B01D2201/50—Means for dissipating electrostatic charges
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2239/00—Aspects relating to filtering material for liquid or gaseous fluids
    • B01D2239/04—Additives and treatments of the filtering material
    • B01D2239/0435—Electret
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2239/00—Aspects relating to filtering material for liquid or gaseous fluids
    • B01D2239/06—Filter cloth, e.g. knitted, woven non-woven; self-supported material
    • B01D2239/0604—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
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2239/00—Aspects relating to filtering material for liquid or gaseous fluids
    • B01D2239/06—Filter cloth, e.g. knitted, woven non-woven; self-supported material
    • B01D2239/065—More than one layer present in the filtering material
    • B01D2239/0659—The layers being joined by needling
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2239/00—Aspects relating to filtering material for liquid or gaseous fluids
    • B01D2239/12—Special parameters characterising the filtering material
    • B01D2239/1291—Other parameters

Definitions

  • ENHANCED ELECTRET NEEDLED FILTRATION MEDIA COMPOSITES This invention pertains to filtration media composites, and pertains particularly to gas filtration media composites formed of an electret media layer attached uniformly to a second media layer by controlled needling so as to provide media composites having enhanced performance for gas filtration systems.
  • Layered filtration media for removing fine solid particulate matter from gases in which it is suspended are generally known, and may include either a layer of blended electrostatic fibers on an electret layer material and a conventional non- woven fibrous layer.
  • U.S. Patent No. 2,916,038 to Wade discloses a tobacco smoke filter formed either of organic fiber electrets or a mixture of such electret fibers with non-electret fibers, such as natural or synthetic fibers of non- uniform diameter. The fibers may be rolled together and also twisted to form a cylindrical-shaped mass which can be bonded together by use of a binder or by heat.
  • 4,257,791 to Wald discloses a filtering medium formed of non- woven needled textile material having a bulk density gradient such that the front or facing portion has a greater bulk density than the rear portion of the filter.
  • U.S. Patent No. 4,798,850 to Brown discloses a blended fibrous filter material in which two types of fibers each carrying opposite electric charges are needled together so as to attract and retain dust particles and provide high filtration efficiency.
  • U.S. Patent No. 4,880,448 to Scherrer discloses a double layer filter insert for an air cleaning apparatus, including a first pre-filter of polyester fibers as an upper or outer layer facing the inflow of dust laden air, and a second layer of an electrostatic nonwoven fabric loosely disposed behind as a lower or inner layer.
  • U.S. Patent No. 4,917,942 to Winters discloses a fibrous filtration laminate including a self-supporting non-woven fabric and an intertangled non- woven mat of electret containing micro fibers deposited on and adhering to the first layer.
  • U.S. Patent No. 5,1 12,677 to Tani et al discloses an electret sheet construction including a porous sheet made of a dielectric polymer and at least one solid material selected from organic, inorganic materials, and metallic materials, and includes material spaced at various intervals on the surface of the dielectric polymer.
  • 35,236 to Nolan discloses an air filter construction employing layers of woven media within a frame, increasing two layers of electrostatic polypropylene woven fabric in an "egg-crate" pattern, each separated by a centrally disposed polyester pad, and held together through a frame device.
  • these prior filtration media constructions have been found useful, further improvements are desirable to provide filtration media having increased durability and filtration efficiency for fine particle removal from flowing gas streams.
  • This invention provides an enhanced filtration media composite for removing particles from flowing gas streams.
  • the composites include a first media layer in the form of an electret fibers (electrostatic composition) that is formed of about 50 wt.% of polypropylene fibers and 50 wt.% of modacrylic fibers such as is disclosed in U.S. Patent No. 4,798,850 and available commercially.
  • the second media layer is formed of non- woven polyester fibers, and may include 80 wt.% of 3 denier x 7.6 cm long polyester staple and 20 wt.% 1.4 denier x 3.8 cm long polyester staple.
  • the second media layer (polyester staple) is applied or directed to the first media layer through a carding procedure by an apparatus which combs and orients such media prior to it being needle punched uniformly to the second media, resulting in each of these two media layers being uniformly intertwined with each other so as to form a single composite structure.
  • the bulk density of the resultant composite structure can be varied during the needling operation.
  • each of the individual media layers are generally known, the combination of these two media layers being uniformly needled together provides an unobvious synergistic effect and results in enhanced mechanical and physical properties not heretofore possible with non-woven air filtration media.
  • the fibers of either media layer can be beneficially needled into the other layers.
  • fibers of the first electret media layer are uniformly needled into the second non-woven fibrous layer to a selected needling depth and spacing. Accordingly, this invention advantageously provides enhanced filtration media composites for filtering flowing gas streams, and method for making the composites in which a first electret layer is uniformly joined to a second non- woven layer by utilizing a selective needling configuration and procedures.
  • Fig. 1 is an enlarged cross-sectional sketch showing the layered filter media composite constructed by selective needling according to this invention
  • Fig. 2 is a schematic cross-sectional drawing generally showing the needling apparatus and method for manufacture of the filter media composites of this invention
  • Fig. 3 is a graph showing filter composite pressure differential (millimeter of water gauge) plotted vs. gas flow velocity at the media face (cm/sec.) for various filter media and composites
  • Fig. 4 is a graph showing filter particle removal efficiency percentages plotted vs. particle size (in microns) for various filter media and composites
  • Fig. 1 is an enlarged cross-sectional sketch showing the layered filter media composite constructed by selective needling according to this invention
  • Fig. 2 is a schematic cross-sectional drawing generally showing the needling apparatus and method for manufacture of the filter media composites of this invention
  • Fig. 3 is a graph showing filter composite pressure differential (millimeter of water gauge) plotted vs. gas flow velocity at the media face (c
  • a layered composite filter media 10 is characterized by a first electret fibrous layer 12 being uniformly attached by being needled at 13 onto a second non-woven fibrous layer 14.
  • This idealized cross- sectional sketch of the layered media composite 10 has the electret layer 12 depicted with an equal number of positively and negatively charged fibers.
  • the mechanical layer 14 is depicted by non-charged fibers in the lower layer.
  • the term electret used for the first media layer 12 describes a fibrous gas filtration media in which individual fibers carry an electrostatic charge, while the media, as a whole has essentially a neutral charge.
  • Such electret fibers may behave like a mini capacitor, with one side of the fiber having a negative charge and other side having a positive charge.
  • the addition of an electrostatic charge to the fibers results in increased particle retention and removal efficiency, while the gas flow pressure drop through the media remains essentially unchanged.
  • the increase in filtration efficiency is primarily attributed to the charged fibers attracting particles having an opposite charge, and the attraction of neutral particles when a dipole is induced by the charges on the fibers.
  • the first electret media layer is generally described in U.S. Patent No.
  • the second media layer 14 is made from staple polyester fibers having two different denier sizes and lengths.
  • the fibers are carded, needlepunched on one side using barbed needles that intertwine the fibers with those of the adjacent layer, thereby creating a uniform mechanically bonded composite which has a tortuous gas flow path for particle capture in the composite media 10.
  • the needle bonding apparatus and method for manufacture of the filter media composite 10 as generally shown by Fig. 2 has the upper fiber web 12 formed of electret and the lower polyester fiber web 14 are both advanced to the needle zone 20.
  • the webs 12 and 14 are both pushed and pressed into position through draw-in rollers and belt units 15 and 16. such that both webs are moved into the needle zone 20.
  • the needling zone 20 includes an upper hole plate 17 and a lower hole plate 18 and it is at this location where the media needling media operation occurs.
  • a needle beam 20 holds a needle board 23 containing multiple needles 24 equally spaced apart. The needle beam is driven by a rotary drive mechanism 26 which causes the plurality of needles 24 affixed to the needle beam 22 through needle board 23 to act on the respective layers 12 and 14 of media which are properly positioned during needling through lower and upper hole plates 17, 18.
  • the method necessary for manufacturing the composite filter products according to this invention include the following basic steps: 1. Blending the fibers, e.g. 80%-20% polyester fibers together to provide desired weight per unit area of media. 2. Carding, in which the blending step No.1 is advanced to where the staple is opened, cleaned, aligned and formed into a continuous web of entwined strands of fibrous material. 3. Cross-lapping in which adjacent multiple layers of web fibers are deposited one with respect to another. 4.
  • Needling by which procedure loose fibers are converted into a coherent non-woven fabric on a needle loom by punching fibers from one layer to interconnect with fibers of the adjacent layer, e.g. electret fiber into the polyester substrate and withdrawing the needles, thereby leaving the media fibers entangled so as to form a unitary composite structure.
  • This needling step is accomplished by utilizing a needle density or spacing of 645-1290 cm 2 , a needle penetration from one layer into the adjacent layer of 0.127-2.54 cm depending on layer thickness.
  • the needling penetrations from the first media layer into the second media layer should be at least 20% and need not exceed about 60% of the second layer thickness and is preferably about 30-50% penetration.
  • a useful needling rate is 300-1500 repetitions/minute.
  • the needles preferably are driven to a depth of 0.15 to 2.03 cm with the needling density of 120-180 penetrations/2.54 cm at a speed of 500 to 1200 revolutions/minute.
  • the two media layers are bonded into one composite 10 by action of the many barbed needles 24 which entangles the fiber of the electret media with the fibers of the polyester media.
  • the upper electret layer 12 has a thickness range from 0.02 to 1.9 cm and the lower polyester layer has a thickness range of 0.02 to 1.9 cm.
  • the resulting needled composite media will have a thickness range of 0.02 to 1.9 cm.
  • the polarization of particles as they approach the charged fibers is capable of polarizing sites on the downstream needlepunch fibers which in turn attract and retain particles.
  • the electret layer is located upstream of the needlepunch media.
  • the first electret layer 12 located downstream of the second needlepunch media 14.
  • the surface finish on the needlepunch second layer 14 may be utilized for cake buildup and release and, in this case, it would be facing the gas flow stream.
  • the first electret layer 12 is preferably filtration needled into the second polyester layer or substrate 14. It is important to control the needle spacing and depth of needle penetration as well as the needle stroke rate into the polyester substrate within the specified ranges during the needling operation. By such control, it is possible to provide desired density of the media composite end product which contributes to the improved characteristics provided by the product.
  • the two polyester staple fibers be needled, namely, the 80 wt.% polyester staple being needled with the 20 wt.% polyester staple to form a polyester substrate.
  • both the 50 wt.% polypropylene and 50 wt % modacrylic electrets are both simultaneously needled into the polyester substrate.
  • the depth of needle penetration by the needles with electret penetrating into the polyester second layer substrate is carefully controlled. A range of penetration is 1.57 to 2.54 cm (as measured from the top surface of the polyester substrate) has been found to be useful
  • NP 400 g/m 2 polyester needlepunch media material * composed of 80 wt.% 3 denier x 7.62 cm polyester staple and 20 wt.% 1.4 denier by 3.81 cm polyester staple.
  • 30 30 g/m 2 electret media** composed of 50 wt.% 2.8 decitex x 50 mm polypropylene staple and 50 wt.% 3.3 decitex x 51 mm monocrylic staple.
  • 70 70 g/m 2 electret media composed of same 50:50 composition of polypropylene and monocrylic fibers as (b), and 400 gram basis weight polyester substrate compared of same composition as (a).
  • Feed Particles utilized neutralized PTI Fine (International Standards Organization fine sized particles) with a mass concentration of 200 mg/m 3 .
  • Efficiency testing utilized neutralized polydispersed potassium chloride (KG).
  • the filter media designed a, c and e were tested for particle loading at a media face velocity of 15 cm/s
  • the terminal pressure drop across the filter was 22-23 mm water gauge
  • An absolute filter was placed downstream from the test media to capture any particles passing through the test media.
  • Particle Removal Efficiency Filter media designated a, b, c, d, and c were tested for particle removal efficiency by particle size at a media face gas velocity of 15 cm s. Their pressure air flow rates of drops were determined at 5, 10, 15, 20, 25 and 30 m 3 /s.
  • the effective filtration area of the tested media was 1858 cm 2 .
  • composite filter structures produced according to this invention exhibit much better particle removal efficiencies than for the sum of the individual component layers, particularly for the smaller size particles being filtered.
  • This improvement indicates that the mechanisms of particle removal operating in the media composites are synergistic in effect and unobvious, and substantially exceed what would be expected from merely observing the filtration performance of the individual component layers.
  • the sample testing established conclusively that the composite (c) produced unexpected results substantially in excess of what would normally be expected when combining (a) and (b), and established improved results by a magnitude of twice to what would normally be expected from the combined filter composites.
  • the filter media composite testing was conducted under controlled conditions with: dust particle sizes in range of 0.3 to 0.5 microns and 0.7 to 1.0 microns. The dust particles were introduced using a potassium chloride KC1 aerosol flowing at 15 cm sec through 1858 cm 2 of composite media formed of needle punched
  • Particle removal efficiency refers to measurement of upstream particle flow vs. downstream particle flow.
  • Test media weight gain (gm) 9.5 14.3 24.6
  • the new filter media composites provide improved performance because they provide an increased tortuous path for particle capture.
  • the flow of air or other gases through the media composite is interrupted and diverted from a straight path by the random orientation of media fibers due to the needling method and composite construction, and results in substantial particle capture and retention in the filter composite.
  • the filter media composites of this invention should be useful in industrial dust collection installations, including pulse-jet bag houses, equipment protection, and at the point-of-emission in the workplace
  • lower basis weight components should extend their use to other applications, including HVAC, room air purifiers, cabin air filters, and vacuum cleaner filters.

Landscapes

  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Filtering Materials (AREA)

Abstract

L'invention concerne un composite de milieu de filtrage amélioré, comprenant une première couche (12) d'un milieu électret, fixée uniformément sur une seconde couche (14) d'un milieu fibreux non tissé, à l'aide d'une procédure et d'une structure spéciales, de manière à obtenir une résistance mécanique et une capacité de rétention de particules accrues. La première couche (12) du milieu électret renferme 50 % en poids d'un mélange de polypropylène et de fibres modacryliques, et la seconde couche (14) du milieu fibreux non tissé est composée de 80 % de fibres discontinues de polyester 3 deniers x 7,6 cm et de fibres discontinues de polyester 1,4 denier x 3,8 cm, les fibres d'une couche étant sélectivement aiguilletées dans l'autre couche, de façon à ce que la profondeur et les répétitions de pénétration des aiguilles soient contrôlées, afin d'obtenir un composite à résistance mécanique et à performance de filtrage améliorées.
PCT/US1998/007142 1998-04-08 1998-04-08 Composites ameliores de milieu de filtrage Ceased WO1999052619A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
PCT/US1998/007142 WO1999052619A1 (fr) 1998-04-08 1998-04-08 Composites ameliores de milieu de filtrage

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
PCT/US1998/007142 WO1999052619A1 (fr) 1998-04-08 1998-04-08 Composites ameliores de milieu de filtrage

Publications (1)

Publication Number Publication Date
WO1999052619A1 true WO1999052619A1 (fr) 1999-10-21

Family

ID=22266808

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/US1998/007142 Ceased WO1999052619A1 (fr) 1998-04-08 1998-04-08 Composites ameliores de milieu de filtrage

Country Status (1)

Country Link
WO (1) WO1999052619A1 (fr)

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
RU2157274C1 (ru) * 2000-03-06 2000-10-10 Открытое акционерное общество "Залесье" Фильтрующий материал
EP1208900A1 (fr) * 2000-11-28 2002-05-29 Carl Freudenberg KG Procédé de fabrication d'un nontissé triboélectriquement chargé
WO2009089891A3 (fr) * 2008-01-15 2010-03-18 Hydac Filtertechnik Gmbh Filtre
CN106536017A (zh) * 2014-07-30 2017-03-22 日本宝翎株式会社 过滤材料、使用该过滤材料的滤芯、及过滤材料的制备方法
EP1447121B2 (fr) † 2001-11-21 2017-11-01 Mitsubishi Heavy Industries, Ltd. Filtre et dispositif de collecte de poussiere et dispositif d'admission de turbine a gaz
WO2018156561A1 (fr) 2017-02-21 2018-08-30 Hollingsworth & Vose Company Milieu filtrant contenant un électret
US12220659B2 (en) 2017-02-21 2025-02-11 Hollingsworth & Vose Company Electret-containing filter media

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS6283016A (ja) * 1985-10-08 1987-04-16 Toyobo Co Ltd 濾材
US4798850A (en) * 1986-05-19 1989-01-17 National Research Development Corporation Blended-fibre filter material
US5230800A (en) * 1992-02-20 1993-07-27 Minnesota Mining And Manufacturing Company Scrim inserted electrostatic fibrous filter web

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS6283016A (ja) * 1985-10-08 1987-04-16 Toyobo Co Ltd 濾材
US4798850A (en) * 1986-05-19 1989-01-17 National Research Development Corporation Blended-fibre filter material
US5230800A (en) * 1992-02-20 1993-07-27 Minnesota Mining And Manufacturing Company Scrim inserted electrostatic fibrous filter web

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
DATABASE WPI Section Ch Week 8721, Derwent World Patents Index; Class A88, AN 87-146400, XP002085195 *

Cited By (18)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
RU2157274C1 (ru) * 2000-03-06 2000-10-10 Открытое акционерное общество "Залесье" Фильтрующий материал
EP1208900A1 (fr) * 2000-11-28 2002-05-29 Carl Freudenberg KG Procédé de fabrication d'un nontissé triboélectriquement chargé
TR200103364A3 (tr) * 2000-11-28 2002-06-21 Carl Freudenberg Triboelektrik yüklü bir yapagi maddesinin üretim yöntemi.
EP1447121B2 (fr) † 2001-11-21 2017-11-01 Mitsubishi Heavy Industries, Ltd. Filtre et dispositif de collecte de poussiere et dispositif d'admission de turbine a gaz
EP2985066A1 (fr) * 2008-01-15 2016-02-17 Hydac Filtertechnik Gmbh Filtre avec un media de filtration adapté contre la création de charges électriques
WO2009089891A3 (fr) * 2008-01-15 2010-03-18 Hydac Filtertechnik Gmbh Filtre
US9108128B2 (en) 2008-01-15 2015-08-18 Hydac Filtertechnik Gmbh Filter
EP2977090A1 (fr) * 2008-01-15 2016-01-27 Hydac Filtertechnik Gmbh Filtre avec un media de filtration adapté contre la création de charges électriques
JP2013188745A (ja) * 2008-01-15 2013-09-26 Hydac Filtertechnik Gmbh フィルタ
EP2987545A1 (fr) * 2008-01-15 2016-02-24 Hydac Filtertechnik Gmbh Filtre avec un media de filtration adapté contre la création de charges électriques
US8709249B2 (en) 2008-01-15 2014-04-29 Hydac Filtertechnik Gmbh Filter
CN106536017A (zh) * 2014-07-30 2017-03-22 日本宝翎株式会社 过滤材料、使用该过滤材料的滤芯、及过滤材料的制备方法
EP3175902A4 (fr) * 2014-07-30 2018-03-14 Japan Vilene Company, Ltd. Matériau de filtration, élément de filtre l'utilisant, et procédé de fabrication de matériau de filtration
US10525392B2 (en) 2014-07-30 2020-01-07 Japan Vilene Company, Ltd. Filtration material, filter element using same, and manufacturing method of filtration material
CN106536017B (zh) * 2014-07-30 2020-03-13 日本宝翎株式会社 过滤材料、使用该过滤材料的滤芯、及过滤材料的制备方法
WO2018156561A1 (fr) 2017-02-21 2018-08-30 Hollingsworth & Vose Company Milieu filtrant contenant un électret
EP3585499A4 (fr) * 2017-02-21 2020-12-23 Hollingsworth & Vose Company Milieu filtrant contenant un électret
US12220659B2 (en) 2017-02-21 2025-02-11 Hollingsworth & Vose Company Electret-containing filter media

Similar Documents

Publication Publication Date Title
CA2027687C (fr) Materiau de filtration et methode de fabrication connexe
EP0375234B1 (fr) Matériau de filtration non tissé
EP0714463B1 (fr) Procede de charge d'un filtre a electret
EP2212006B1 (fr) Sacs filtres et milieux intérieurs thermiquement stabilisés
EP2142275B1 (fr) Dépoussiéreurs à sacs filtrants
US6197709B1 (en) Meltblown composites and uses thereof
HK1009316B (en) Filtration media and method of manufacture
US5874373A (en) Enhanced electret needled filtration media and composites
JP4923353B2 (ja) エレクトレット濾材およびその製造方法
EP2122030A1 (fr) Feutre filtre sous forme de film scindé de microfibres et procédé de fabrication
JP4009514B2 (ja) 生分解性空気清浄用フィルター
AU641744B2 (en) Filter
WO1999052619A1 (fr) Composites ameliores de milieu de filtrage
US5540756A (en) Electrostatic filter and method of filtering dust
EP4593983A1 (fr) Filtres à capacités de filtrage électrostatique
JP4882985B2 (ja) エレクトレット濾材およびフィルタユニット
EP1214134A1 (fr) Moyens de filtration et fabrication correspondante
Dugan et al. Synthetic Split Microfiber Technology for Filtration
GB2382537A (en) Filtration medium
CA2474282C (fr) Media filtrant electretes
JP2025532042A (ja) フィルタ媒体及びフィルタ
JPS5910320A (ja) 「ろ」材

Legal Events

Date Code Title Description
AK Designated states

Kind code of ref document: A1

Designated state(s): CA JP

AL Designated countries for regional patents

Kind code of ref document: A1

Designated state(s): AT BE CH CY DE DK ES FI FR GB GR IE IT LU MC NL PT SE

NENP Non-entry into the national phase

Ref country code: CA

121 Ep: the epo has been informed by wipo that ep was designated in this application
NENP Non-entry into the national phase

Ref country code: CA

122 Ep: pct application non-entry in european phase