GB2190689A - Blended fibre filter material - Google Patents

Blended fibre filter material Download PDF

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Publication number
GB2190689A
GB2190689A GB08611365A GB8711365A GB2190689A GB 2190689 A GB2190689 A GB 2190689A GB 08611365 A GB08611365 A GB 08611365A GB 8711365 A GB8711365 A GB 8711365A GB 2190689 A GB2190689 A GB 2190689A
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United Kingdom
Prior art keywords
material according
filter material
fibres
fibre
afilter
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Granted
Application number
GB08611365A
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GB2190689B (en
GB8711365D0 (en
Inventor
Richard Colin Brown
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National Research Development Corp UK
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National Research Development Corp UK
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Publication of GB8711365D0 publication Critical patent/GB8711365D0/en
Publication of GB2190689A publication Critical patent/GB2190689A/en
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Publication of GB2190689B publication Critical patent/GB2190689B/en
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Classifications

    • D—TEXTILES; PAPER
    • D04—BRAIDING; LACE-MAKING; KNITTING; TRIMMINGS; NON-WOVEN FABRICS
    • D04H—MAKING TEXTILE FABRICS, e.g. FROM FIBRES OR FILAMENTARY MATERIAL; FABRICS MADE BY SUCH PROCESSES OR APPARATUS, e.g. FELTS, NON-WOVEN FABRICS; COTTON-WOOL; WADDING ; NON-WOVEN FABRICS FROM STAPLE FIBRES, FILAMENTS OR YARNS, BONDED WITH AT LEAST ONE WEB-LIKE MATERIAL DURING THEIR CONSOLIDATION
    • D04H1/00—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres
    • D04H1/40—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres from fleeces or layers composed of fibres without existing or potential cohesive properties
    • D04H1/42—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres from fleeces or layers composed of fibres without existing or potential cohesive properties characterised by the use of certain kinds of fibres insofar as this use has no preponderant influence on the consolidation of the fleece
    • D04H1/4282—Addition polymers
    • D04H1/4291—Olefin series
    • D—TEXTILES; PAPER
    • D04—BRAIDING; LACE-MAKING; KNITTING; TRIMMINGS; NON-WOVEN FABRICS
    • D04H—MAKING TEXTILE FABRICS, e.g. FROM FIBRES OR FILAMENTARY MATERIAL; FABRICS MADE BY SUCH PROCESSES OR APPARATUS, e.g. FELTS, NON-WOVEN FABRICS; COTTON-WOOL; WADDING ; NON-WOVEN FABRICS FROM STAPLE FIBRES, FILAMENTS OR YARNS, BONDED WITH AT LEAST ONE WEB-LIKE MATERIAL DURING THEIR CONSOLIDATION
    • D04H1/00—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres
    • D04H1/40—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres from fleeces or layers composed of fibres without existing or potential cohesive properties
    • D04H1/42—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres from fleeces or layers composed of fibres without existing or potential cohesive properties characterised by the use of certain kinds of fibres insofar as this use has no preponderant influence on the consolidation of the fleece
    • D04H1/425—Cellulose series
    • D—TEXTILES; PAPER
    • D04—BRAIDING; LACE-MAKING; KNITTING; TRIMMINGS; NON-WOVEN FABRICS
    • D04H—MAKING TEXTILE FABRICS, e.g. FROM FIBRES OR FILAMENTARY MATERIAL; FABRICS MADE BY SUCH PROCESSES OR APPARATUS, e.g. FELTS, NON-WOVEN FABRICS; COTTON-WOOL; WADDING ; NON-WOVEN FABRICS FROM STAPLE FIBRES, FILAMENTS OR YARNS, BONDED WITH AT LEAST ONE WEB-LIKE MATERIAL DURING THEIR CONSOLIDATION
    • D04H1/00—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres
    • D04H1/40—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres from fleeces or layers composed of fibres without existing or potential cohesive properties
    • D04H1/42—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres from fleeces or layers composed of fibres without existing or potential cohesive properties characterised by the use of certain kinds of fibres insofar as this use has no preponderant influence on the consolidation of the fleece
    • D04H1/4282—Addition polymers
    • D04H1/43—Acrylonitrile series
    • D—TEXTILES; PAPER
    • D04—BRAIDING; LACE-MAKING; KNITTING; TRIMMINGS; NON-WOVEN FABRICS
    • D04H—MAKING TEXTILE FABRICS, e.g. FROM FIBRES OR FILAMENTARY MATERIAL; FABRICS MADE BY SUCH PROCESSES OR APPARATUS, e.g. FELTS, NON-WOVEN FABRICS; COTTON-WOOL; WADDING ; NON-WOVEN FABRICS FROM STAPLE FIBRES, FILAMENTS OR YARNS, BONDED WITH AT LEAST ONE WEB-LIKE MATERIAL DURING THEIR CONSOLIDATION
    • D04H1/00—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres
    • D04H1/40—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres from fleeces or layers composed of fibres without existing or potential cohesive properties
    • D04H1/42—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres from fleeces or layers composed of fibres without existing or potential cohesive properties characterised by the use of certain kinds of fibres insofar as this use has no preponderant influence on the consolidation of the fleece
    • D04H1/4326—Condensation or reaction polymers
    • D04H1/435—Polyesters
    • D—TEXTILES; PAPER
    • D04—BRAIDING; LACE-MAKING; KNITTING; TRIMMINGS; NON-WOVEN FABRICS
    • D04H—MAKING TEXTILE FABRICS, e.g. FROM FIBRES OR FILAMENTARY MATERIAL; FABRICS MADE BY SUCH PROCESSES OR APPARATUS, e.g. FELTS, NON-WOVEN FABRICS; COTTON-WOOL; WADDING ; NON-WOVEN FABRICS FROM STAPLE FIBRES, FILAMENTS OR YARNS, BONDED WITH AT LEAST ONE WEB-LIKE MATERIAL DURING THEIR CONSOLIDATION
    • D04H1/00—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres
    • D04H1/40—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres from fleeces or layers composed of fibres without existing or potential cohesive properties
    • D04H1/42—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres from fleeces or layers composed of fibres without existing or potential cohesive properties characterised by the use of certain kinds of fibres insofar as this use has no preponderant influence on the consolidation of the fleece
    • D04H1/4382—Stretched reticular film fibres; Composite fibres; Mixed fibres; Ultrafine fibres; Fibres for artificial leather
    • D04H1/43835—Mixed fibres, e.g. at least two chemically different fibres or fibre blends
    • D—TEXTILES; PAPER
    • D04—BRAIDING; LACE-MAKING; KNITTING; TRIMMINGS; NON-WOVEN FABRICS
    • D04H—MAKING TEXTILE FABRICS, e.g. FROM FIBRES OR FILAMENTARY MATERIAL; FABRICS MADE BY SUCH PROCESSES OR APPARATUS, e.g. FELTS, NON-WOVEN FABRICS; COTTON-WOOL; WADDING ; NON-WOVEN FABRICS FROM STAPLE FIBRES, FILAMENTS OR YARNS, BONDED WITH AT LEAST ONE WEB-LIKE MATERIAL DURING THEIR CONSOLIDATION
    • D04H1/00—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres
    • D04H1/40—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres from fleeces or layers composed of fibres without existing or potential cohesive properties
    • D04H1/44—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres from fleeces or layers composed of fibres without existing or potential cohesive properties the fleeces or layers being consolidated by mechanical means, e.g. by rolling
    • D04H1/46—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres from fleeces or layers composed of fibres without existing or potential cohesive properties the fleeces or layers being consolidated by mechanical means, e.g. by rolling by needling or like operations to cause entanglement of fibres
    • D—TEXTILES; PAPER
    • D04—BRAIDING; LACE-MAKING; KNITTING; TRIMMINGS; NON-WOVEN FABRICS
    • D04H—MAKING TEXTILE FABRICS, e.g. FROM FIBRES OR FILAMENTARY MATERIAL; FABRICS MADE BY SUCH PROCESSES OR APPARATUS, e.g. FELTS, NON-WOVEN FABRICS; COTTON-WOOL; WADDING ; NON-WOVEN FABRICS FROM STAPLE FIBRES, FILAMENTS OR YARNS, BONDED WITH AT LEAST ONE WEB-LIKE MATERIAL DURING THEIR CONSOLIDATION
    • D04H1/00—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres
    • D04H1/70—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres characterised by the method of forming fleeces or layers, e.g. reorientation of fibres
    • D04H1/74—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres characterised by the method of forming fleeces or layers, e.g. reorientation of fibres the fibres being orientated, e.g. in parallel (anisotropic fleeces)
    • 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
    • B01D2239/12—Special parameters characterising the filtering material
    • B01D2239/1225—Fibre length
    • 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
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T428/00—Stock material or miscellaneous articles
    • Y10T428/29—Coated or structually defined flake, particle, cell, strand, strand portion, rod, filament, macroscopic fiber or mass thereof
    • Y10T428/2913—Rod, strand, filament or fiber
    • Y10T428/2933—Coated or with bond, impregnation or core
    • Y10T428/2964—Artificial fiber or filament
    • Y10T428/2967—Synthetic resin or polymer
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T428/00—Stock material or miscellaneous articles
    • Y10T428/29—Coated or structually defined flake, particle, cell, strand, strand portion, rod, filament, macroscopic fiber or mass thereof
    • Y10T428/2913—Rod, strand, filament or fiber
    • Y10T428/2973—Particular cross section
    • Y10T428/2975—Tubular or cellular

Description

1 GB 2 190 689 A 1
SPECIFICATION most preferably at least 50weight % acrylonitrile.
The ratio of fibre (i) to fibre (ii) is preferably from Blended-fibre filter material 30:70 to 80:20 by surface area, more preferably from 40:60 to 70:30.
This invention is a f ilter material of blended fibres. 70 The f ibres are preferably finer than 100 The f ilter material may f ind a pplication i n dust micrometres, preferably from 10 to 25 micrometres helmets, respirators, suction cleaners and and preferably the fibre (i) cross-sectional area does air-conditioning systems as a clisposablefilter not differfrom thefibre (ii) crosssectional area by element, and even as a duster. more than a factor of 3. Staple length is preferably In airfilters, a low resistance to airflow is 75 from 30 to 200 mm, more preferably 40 to 100 mm.
desirable, coupled with, of course, a high filtration Thefibres (i) or (H) or both are preferably crimped.
efficiency (= a high probabilitythat a particle borne Preferablythe material is a felt, preferably made by in the airflowthrough thefilterwill be captured by carding thefibres into a fleece and needling them.
thefilter). These properties can be met by a filter The carding is preferably performed by passing the material having an open structure by carrying 80 material over a conventional two-swift card, orto electric charge, to attract dust particles. Such a filter substantially the equivalent extent by any alternative material is described in British Patent Specification means. (The carding is likely to impose a practical
384052, wherein wool fibres are carded with resin limit on the fine-ness of usable fibres. The finerthe particles. In this filter material, the action during fibres, the more efficientthe filter butthe higherthe manufacture of rubbing the wool againstthe resin 85 resistance to airflow). The carding step must not be imparts a persistent negative charge to the resin and allowed to contaminate the fibres with anti-static an induced positive charge to the wool. These agent or lubricant.
charges attract dust particles. The invention will now be described by way of Itwould be desirable to find an airfilterwith a high example.
filtration efficiency, which is reasonably priced, 90 The filter material is a mixture of two different which has a low resistance to airflow and which is crimped synthetic polymerfibres carded into a fleece non-flammable. and then needled to form a felt. The fibres are well According to the present invention, a filter material mixed, and they became electrical ly charged during comprises a blend of (i) clean polyolefine fibres and carding. The electric charge that they hold is critical (H) clean fibres of a substituted addition polymer, 95 in effecting the capture of small dust particles bythe preferably a polymer comprising one or more material.
substituted hydrocarbons; the substituent may be The firstfibre is polypropylene 20 micrometres -M or a halogen (preferably f 1 uorine orchlorine), thick,which in commerce is 2.8 decitex (n tex = n and the hydrocarbon may be a polyolefine, 9/km). This may be e.g. round ortrilobal.
preferably polyethylene or polypropylene. Thefibres 100 Polypropylene from various manufacturers has been (H) couldthus contain forexample one or moreof tried, andfoundto befairly consistent. Pigmented chloroethylene units, for example -CHCl-CH2-or polypropylene is acceptable. Commercially -CC12-CH2-, oracrylonitrile units -CH2-C(CN)H-, or produced polypropylene fibres normally haveon tetrafluoroethylene units -CF2-CF2-, and couldthus them a "spin finish", which is a mixture of lubricant beforexample acrylic, polyvinyl chloride, 105 and anti-static agent. Polypropylene can be made polyvinylidene chloride, vinyl chloride -vinylidene finish-free quite easily, but usually it is not. This chloride copolymer, chlorinated polyvinyl chloride, finish is removed before thefibres are carded. Any of polytetrafluorethylene or (preferably) modacrylic. By the usual processes of textile scouring could be clean"we mean thatthefibre has no coating of used, such as detergent, alkali or solvent scouring; lubricant or anti-static agent, orthat any such coating 110 scouring with a non-ionic detergent is quite effective was removed before blending,for example by provided it isthorough. If thefibres are moderately scouring with a non-ionic detergent. By clean thefilterwill be moderately good. Then the modacrylic" we mean a copolymer comprising fibre is well rinsed.
from 35to 85weight percent acrylonitrile units and The second fibre is modacrylic 18 micrometres preferably having the balance made up substantially 115 thick, in particularTeklan (described above) of 3.5 of other addition-polymer-forming units, preferably decitex. Dyed modacrylicfibre is acceptable but vinyl ester or halogenated hydrocarbon such asvinyl undyed modacrylicfibre is preferred. Commercial chloride orvinylidene chloride. modacryliefibre cannot in practice be madewithout The polyolefine fibres (i) may be polyethylene, a "spin finish", which (as with polypropylene) is a ethyl ene-propyl ene copolymer, or (preferably) 120 mixture of lubricant and antistatic agent. This finish polypropylene. is removed before the fibres are carded. Any of the The modacrylic is preferably Kanekalon (trade usual processes of textile scouring could be used, mark) by Kanegafuchi Chem. Co. and Kariekalon Co. such as detergent, alkali or solvent scouring; of Japan orTeklan (trade mark) by Courtaulds. scouring with a non-ionic detergent is quite effective Kanekalon comprises 55 weight % vinyl chloride. 125 provided it is thorough. If the fibres are moderately Teklan comprises 50 weight % of vinylidene chloride clean the filterwill be moderately good:Some and under 2 weight % of a third monomerfor benefit may be obtained from an alkali scour or providing dye sites. The balance in both cases is chemical leaching. Acid scouring is not substantially aerylonitrile. The modacrylic preferably recommended.
comprises at least 40, more preferably at least 44, 130 These fibres are carded using a two-swift card, 2 GB 2 190 689 A 2 each swift having four worker-stripper units, in In a furthertest, the filter of the inventionwas weight proportions 60 polypropylene: 40 encapsulated in a plastic filter cartridge of atype modacrylic, Le.to givesurface areas roughlyinthe normally used in approved respirators.The cartridge ratio 2: 1, polypropylene: modacrylic, into a fleece. was a short cylinder of approximately 13mm depth The carding causes both fibres to acquire electric 70 and 70 mm diameter. The filterwas subjected to a charge,which, afterfalling during the next day, test conforming in all essential features to that part of thereafter remains at a fairly constant level for the British Standard BS 2091 testfor respirators several months. Thefleece has a mass of 1.5 kg per which comprises measurement of'standard'aerosol square metre. penetration at a volume flow rate of 30 litres/minute The fleeces are lightly needled, using a 75 through the filters, and measurement of the pressure needle-punching loom, at 8mm penetration, 25 drop across thefilter at a flow rate of 85 litres/minute need] i ngs/cm', to form a felt. Depending on the end through the filter.
use, where a stiffer or denserfelt is wanted, heavier According to the Standard, a filter is rated as Class needling may be preferable. A if the aerosol penetration is no greaterthan 10% The fibre processing machines (i.e. card and 80 and the pressure drop is no greaterthan 200 Pa, and needle-loom) are kept clean to avoid contaminating it is rated as Class B if the penetration is no greater the fibres, especiallywith spin finish from previous than 2% (different criteria are applied to filters of batches. Although not strictly essential, preferably differenttypes; 2% penetration is applied to resin all-metal card clothing is used, and if the wool filters; it is the most rigorous and the most needle-loom has boards with wooden backs, a new 85 appropriate forthe filter of the invention) and the board should be used. Card clothing is usually pressure drop no greaterthan 320 Pa.
contaminated with oil, and this must be removed. 1.5 g of the material of the invention encapsulated The fibres may be (coarsely) mixed using a blender in this way gave a penetration of 0.9% and a pressure beforethe carding. The blender should likewise be drop of 63 Pa, and 3.0 g of the material of the kept clean. The carding completes the mixing, butif 90 invention so encapsulated gave a penetration of this is inadequate laterally across thefleece, a 0.3% and a pressure drop of 190 Pa. Both f ilters thus cross-laying stage can be interposed between the satisfied each class of the Standard.
swifts, as is known practice. Sufficienttime has not elapsed for the stability of The resulting filter material has low flammability, the charge on the f ilters described above to be and mayfind use in dust helmets, disposable 95 conclusively established, butfrom previous respirators and elsewhere. experience it is considered that a substantial The performance of the filter depends on its increase in aerosol penetration is likely in thefirst24 packing fraction (proportion of itsvolume occupied hours after manufacture, followed by a much slower byfibres). Thus,the penetration of aerosols in increase. Penetration may double in thefirst 24 general decreases (i.e. the filteris more effective) 100 hours; from the 24 hourvalue it may increase by a and the pressure drop increases (i.e. airflow is more factor of 1.5 in one month and 1.7 in one year.The impeded) asthe packing fraction is increased at filters used in the previous comparison testswere all constantfilter mass per unit area. therefore at least one day old.
At a given packing fraction and mass per unit area,

Claims (1)

  1. filters made from finerfibres are more effective than 105 CLAIMS those
    made from coarser, butthey also have a higher resistance to airflow. The choice of fibre diameter is 1. A filter material which comprises a blend of (i) finally governed by the purpose for which the filter is clean polyolefine fibres and (ii) clean fibres of a intended, but it is likely that the most useful will be substituted addition polymer.
    made from the finest fibres that can be carded 110 2. Afilter material according to Claim 1, wherein without any difficulty. the addition polymer comprises one or more A'standard'aerosol (to B.S. 4400 of 1969) at a fixed substituted hydrocarbons.
    filtration velocity (0.28 m T1) was used on filters 3. Afilter material according to Claim 2, wherein according to the invention, on polypropylene/wool the substituent is -CN or a halogen.
    filters, and on filters made entirelyfrom 115 4. A filter material according to Claim 2 or 3, polypropylene, the respective filters being matched wherein the hydrocarbon is a polyolefine.
    in a first series of comparative tests as regards 5. A filter material according to Claim 4, wherein pressure drop across them (100 Pa atthefiltration the polyolefineof (H) is polyethyleneor velocity), and being matched in a second series asto polypropylene.
    mass per unit area (1.5 kg M-2). 120 6. A filter material according to Claim 4, wherein In the first series of tests (constant pressure drop), the fibres 00 contain one or more of chloroethylene the penetration of the'standard'aerosol was 0.07% units or acrylonitrile units ortetrafluoroethylene through thefilter of the invention, 0.40%through the units.
    polypropylenelwool filters, and 10.2% through the 7. A filter material according to Claim 6, wherein pure polypropylenefilter. In the second series of 125 thefibres (ii) are acrylic, polyvinyl chloride, tests (constantfilter mass per unit area),the polyvinylidene chloride, vinyl chloride -vinylidene penetration of the'standard'aerosol through the chloride copolymer, chlorinated polyvinyl chloride filter of the invention was 0.032%, through the or polytetrafluorethylene.
    polypropylenelwool filterwas 0.31% and through 8. Affiter material according to Claim 6, wherein the pure polypropylene filters was 7.0%. 130thefibres (ii) are modacrylic.
    3 GB 2 190 689 A 3 9. Afilter material according to Claim 8 wherein the modacrylic is a copolymer comprising from 35to 85 weight percent acrylonitrile units and having the balance made up substantially of other 5 addition-polymer- forming units.
    10. Afilter material according to Claim 9, wherein the other additionpolymer-forming units are vinyl ester or halogenated hydrocarbon.
    11. Afilter material according to Claim 8,9 or 10, wherein the modacrylic comprises at least 40% aerylonitrile.
    12. A filter material according to Claim 11, wherein the modacrylic comprises at least44% acrylonitrile.
    13. Afilter material according to Claim 12, wherein the modacrylic comprises at least 50% acrylonitrile.
    14. Afilter material according to any preceding claim, wherein the polyolef ine fibres (i) are polyethylene or ethylene-propylene copolymer.
    15. A filter material according to any of Claims 1 to 13, wherein the polyolefine fibres (i) are polypropylene.
    16. A filter material according to any preceding claim, wherein the ratio of fibre (l) to fibre (ii) is from 30:70to 80:20 by surface area.
    17. A filter material according to Claim 16, wherein the ratio of fibre (i) to fibre (ii) from 40:60to 70:30 by surface area.
    18. Afilter material according to any preceding claim, wherein the fibres arefinerthan 100 micrometres.
    19. A filter material according to Claim 18, wherein the fibre diameters are from 10 to 25 micrometres.
    20. A filter material according to any preceding claim, wherein the fibre (i) cross-sectional area does not differfrom the fibre (ii) crosssectional area by morethan a factor of 3.
    21. Afilter material according to any preceding claim, wherein the fibre staple length is from 30 to 20Omm.
    22. A filter material according to Claim 21 wherein the fibre staple length is from 40 to 100 mm.
    23. A filter material according to any preceding claim, wherein the fibres (i) or (ii) or both are crimped.
    24. Afilter material according to any preceding claim, in theform of a felt.
    25. A filter material according to claim 24, wherein the felt is made by carding the fibres into a fleece and needling them.
    Printed for Her Majesty's Stationery Office by Croydon Printing Company (UK) Ltd, 10187, D8991685. Published by The Patent Office, 25 Southampton Buildings, London, WC2A l AY, from which copies maybe obtained.
GB8711365A 1986-05-19 1987-05-14 Blended-fibre filter material Expired GB2190689B (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB868612070A GB8612070D0 (en) 1986-05-19 1986-05-19 Blended-fibre filter material

Publications (3)

Publication Number Publication Date
GB8711365D0 GB8711365D0 (en) 1987-06-17
GB2190689A true GB2190689A (en) 1987-11-25
GB2190689B GB2190689B (en) 1989-12-06

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GB868612070A Pending GB8612070D0 (en) 1986-05-19 1986-05-19 Blended-fibre filter material
GB8711365A Expired GB2190689B (en) 1986-05-19 1987-05-14 Blended-fibre filter material

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GB868612070A Pending GB8612070D0 (en) 1986-05-19 1986-05-19 Blended-fibre filter material

Country Status (5)

Country Link
US (1) US4798850A (en)
EP (1) EP0246811B1 (en)
DE (1) DE3782764T2 (en)
GB (2) GB8612070D0 (en)
HK (1) HK38195A (en)

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1994012262A1 (en) * 1992-11-23 1994-06-09 W.L. Gore & Associates, Inc. Triboelectric filtration material
DE4241517A1 (en) * 1992-12-10 1994-06-16 Freudenberg Carl Fa Method and device for producing a spunbonded nonwoven
US5540756A (en) * 1990-03-19 1996-07-30 Hoppitt; Bernard Electrostatic filter and method of filtering dust
US5874373A (en) * 1997-03-14 1999-02-23 American Felt & Filter Company Enhanced electret needled filtration media and composites
WO1999058224A1 (en) * 1998-05-13 1999-11-18 Texel Inc. Triboelectric air filter
GB2355215A (en) * 1999-09-14 2001-04-18 Intersurgical Ltd Manufacture of filtration media

Families Citing this family (129)

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Publication number Priority date Publication date Assignee Title
CA1327945C (en) * 1988-05-13 1994-03-22 David L. Braun Elastomeric filtration materials
CA2037942A1 (en) * 1990-03-12 1991-09-13 Satoshi Matsuura Process for producing an electret, a film electret, and an electret filter
JP2849291B2 (en) * 1992-10-19 1999-01-20 三井化学株式会社 Electretized nonwoven fabric and method for producing the same
US5419953A (en) * 1993-05-20 1995-05-30 Chapman; Rick L. Multilayer composite air filtration media
DE4407344C1 (en) * 1994-03-05 1995-05-11 Freudenberg Carl Fa Air filter material, use and production thereof
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DE3782764D1 (en) 1993-01-07
GB8612070D0 (en) 1986-06-25
US4798850A (en) 1989-01-17
EP0246811A2 (en) 1987-11-25
DE3782764T2 (en) 1993-04-01
GB2190689B (en) 1989-12-06
EP0246811A3 (en) 1990-05-16
EP0246811B1 (en) 1992-11-25
GB8711365D0 (en) 1987-06-17

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