WO2010048709A1 - Filter bag, pleatable filtration material therefore, and process of making same - Google Patents

Filter bag, pleatable filtration material therefore, and process of making same Download PDF

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Publication number
WO2010048709A1
WO2010048709A1 PCT/CA2009/001539 CA2009001539W WO2010048709A1 WO 2010048709 A1 WO2010048709 A1 WO 2010048709A1 CA 2009001539 W CA2009001539 W CA 2009001539W WO 2010048709 A1 WO2010048709 A1 WO 2010048709A1
Authority
WO
WIPO (PCT)
Prior art keywords
scrim
pleatable
felt
permeability
ptfe
Prior art date
Application number
PCT/CA2009/001539
Other languages
French (fr)
Inventor
Luc Parent
Sylvain Vieuille
Original Assignee
Sefar Bdh Inc.
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 Sefar Bdh Inc. filed Critical Sefar Bdh Inc.
Priority to CN200980142559.5A priority Critical patent/CN102196851B/en
Priority to AU2009310577A priority patent/AU2009310577B2/en
Priority to EP09822935.4A priority patent/EP2361133B1/en
Priority to KR1020117012216A priority patent/KR101672309B1/en
Priority to US13/126,130 priority patent/US8728401B2/en
Priority to JP2011532472A priority patent/JP2012506764A/en
Publication of WO2010048709A1 publication Critical patent/WO2010048709A1/en

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D39/00—Filtering material for liquid or gaseous fluids
    • B01D39/14—Other self-supporting filtering material ; Other filtering material
    • B01D39/16—Other self-supporting filtering material ; Other filtering material of organic material, e.g. synthetic fibres
    • B01D39/1607—Other self-supporting filtering material ; Other filtering material of organic material, e.g. synthetic fibres the material being fibrous
    • 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
    • D04H1/54—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 by welding together the fibres, e.g. by partially melting or dissolving
    • D04H1/559—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 by welding together the fibres, e.g. by partially melting or dissolving the fibres being within layered webs
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D29/00—Filters with filtering elements stationary during filtration, e.g. pressure or suction filters, not covered by groups B01D24/00 - B01D27/00; Filtering elements therefor
    • B01D29/11—Filters with filtering elements stationary during filtration, e.g. pressure or suction filters, not covered by groups B01D24/00 - B01D27/00; Filtering elements therefor with bag, cage, hose, tube, sleeve or like filtering elements
    • 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
    • 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
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D39/00—Filtering material for liquid or gaseous fluids
    • B01D39/14—Other self-supporting filtering material ; Other filtering material
    • B01D39/16—Other self-supporting filtering material ; Other filtering material of organic material, e.g. synthetic fibres
    • B01D39/1607—Other self-supporting filtering material ; Other filtering material of organic material, e.g. synthetic fibres the material being fibrous
    • B01D39/1623—Other self-supporting filtering material ; Other filtering material of organic material, e.g. synthetic fibres the material being fibrous of synthetic origin
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D39/00—Filtering material for liquid or gaseous fluids
    • B01D39/14—Other self-supporting filtering material ; Other filtering material
    • B01D39/16—Other self-supporting filtering material ; Other filtering material of organic material, e.g. synthetic fibres
    • B01D39/1692—Other shaped material, e.g. perforated or porous sheets
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D43/00—Separating particles from liquids, or liquids from solids, otherwise than by sedimentation or filtration
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D61/00—Processes of separation using semi-permeable membranes, e.g. dialysis, osmosis or ultrafiltration; Apparatus, accessories or auxiliary operations specially adapted therefor
    • B01D61/14—Ultrafiltration; Microfiltration
    • B01D61/147—Microfiltration
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D63/00—Apparatus in general for separation processes using semi-permeable membranes
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D71/00—Semi-permeable membranes for separation processes or apparatus characterised by the material; Manufacturing processes specially adapted therefor
    • B01D71/06—Organic material
    • B01D71/30—Polyalkenyl halides
    • B01D71/32—Polyalkenyl halides containing fluorine atoms
    • B01D71/36—Polytetrafluoroethene
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J20/00—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
    • B01J20/02—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising inorganic material
    • B01J20/06—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising inorganic material comprising oxides or hydroxides of metals not provided for in group B01J20/04
    • B01J20/08—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising inorganic material comprising oxides or hydroxides of metals not provided for in group B01J20/04 comprising aluminium oxide or hydroxide; comprising bauxite
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B15/00—Layered products comprising a layer of metal
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    • B32B15/00—Layered products comprising a layer of metal
    • B32B15/18—Layered products comprising a layer of metal comprising iron or steel
    • B—PERFORMING OPERATIONS; TRANSPORTING
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    • B32B15/00—Layered products comprising a layer of metal
    • B32B15/20—Layered products comprising a layer of metal comprising aluminium or copper
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B27/00—Layered products comprising a layer of synthetic resin
    • B32B27/12—Layered products comprising a layer of synthetic resin next to a fibrous or filamentary layer
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B27/00—Layered products comprising a layer of synthetic resin
    • B32B27/32—Layered products comprising a layer of synthetic resin comprising polyolefins
    • B32B27/322—Layered products comprising a layer of synthetic resin comprising polyolefins comprising halogenated polyolefins, e.g. PTFE
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B5/00—Layered products characterised by the non- homogeneity or physical structure, i.e. comprising a fibrous, filamentary, particulate or foam layer; Layered products characterised by having a layer differing constitutionally or physically in different parts
    • B32B5/22—Layered products characterised by the non- homogeneity or physical structure, i.e. comprising a fibrous, filamentary, particulate or foam layer; Layered products characterised by having a layer differing constitutionally or physically in different parts characterised by the presence of two or more layers which are next to each other and are fibrous, filamentary, formed of particles or foamed
    • B32B5/30—Layered products characterised by the non- homogeneity or physical structure, i.e. comprising a fibrous, filamentary, particulate or foam layer; Layered products characterised by having a layer differing constitutionally or physically in different parts characterised by the presence of two or more layers which are next to each other and are fibrous, filamentary, formed of particles or foamed one layer being formed of particles, e.g. chips, granules, powder
    • 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
    • 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
    • D04H1/40—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
    • D04H1/492—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 by fluid jet
    • 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
    • D04H1/58—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 by applying, incorporating or activating chemical or thermoplastic bonding agents, e.g. adhesives
    • D04H1/64—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 by applying, incorporating or activating chemical or thermoplastic bonding agents, e.g. adhesives the bonding agent being applied in wet state, e.g. chemical agents in dispersions or solutions
    • 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
    • B01D2239/0407—Additives and treatments of the filtering material comprising particulate additives, e.g. adsorbents
    • 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
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B2255/00—Coating on the layer surface
    • B32B2255/02—Coating on the layer surface on fibrous or filamentary layer
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B2255/00—Coating on the layer surface
    • B32B2255/26—Polymeric coating
    • B—PERFORMING OPERATIONS; TRANSPORTING
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    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B2262/00—Composition or structural features of fibres which form a fibrous or filamentary layer or are present as additives
    • B32B2262/02—Synthetic macromolecular fibres
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    • B32B2264/02—Synthetic macromolecular particles
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    • B32B2307/30—Properties of the layers or laminate having particular thermal properties
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Definitions

  • the specification relates to pleatable materials, or fabrics, for use in filtration, and more particularly for use as pleated "filter bags” in baghouse-type dust collectors, for example.
  • a dust collector is an equipment to remove particles in an industrial fume.
  • the collector contains between hundreds to thousands of cylindrical elements referred to as bags.
  • the bags are made of a filtration fabric that is porous. As the gas flows through, the porous filtration fabric collects particles. The particles can form a cake on the surface after minutes of operation, and the bags are typically cleaned by a reversed jet.
  • the efficiency of filtration of bags is related to the total surface area. Typically, if the surface area is increased, then the velocity of gas and particles going through the fabric will be reduced, which decreases the probability of undesired particles going through the fabric and can consequently reduces the particle emissions. Moreover, a higher surface area can reduce the probability of particles getting embedded into the fabric in a manner where they resist the reversed jet, thereby increasing the lifespan of the filter. It is also possible, by increasing the surface area, to increase the capacity of a dust collector. It is thus generally sought to increase the surface area of the bags in dust collectors, where possible.
  • pleated bags have a greater surface area than non-pleated bags (i.e. simply cylindrical bags).
  • Using pleated bags instead of non-pleated bags is thus one way of increasing the surface area without necessarily increasing the overall size of the dust collector system.
  • replacement of non-pleated bags by pleated bags can increase the surface area by two to three times.
  • Pleated bags can be made using a pleatable material which keeps its shape after pleating. The pleating can be done with a pleating machine. Some pleating machines operate at room temperature.
  • pleating machines having heating blades are used to fold the fabric and keep pressure on the pleats until the fabric is cooled back to room temperature.
  • such processes have been used with polymers that can be thermally formed and have a relatively small density.
  • thermosetting resin Some materials that are not thermally formable per se can be made so by adding a thermosetting resin.
  • An example of this is fiberglass felt impregnated with phenolic resin. The temperature of blades allow setting of the phenolic resin which subsequently acts to maintain the shape of the pleats. The reaction being irreversible, the pleats subsequently keep their shape even at high temperature.
  • a filtration material such as a PTFE felt covered by an E-PTFE membrane, which was traditionally known as unpleatable, can now be made pleatable by felting with a pleatable scrim, more particularly a pleatable metallic scrim.
  • a pleatable scrim more particularly a pleatable metallic scrim.
  • metals which are pleatable when provided in apertured sheets, and the pleatability of a metallic scrim can take precedence on the pleatability of both the felted PTFE and the E-PTFE membrane.
  • Felting by hydro-entanglement (spunlacing) can be better suited than neddle-felting when using a metallic scrim.
  • a pleatable filtration material comprising a felt having PTFE fibers felted onto a pleatable metallic scrim, a permeability of at least 20 l/dm 2 /minute at 12 mm of water gauge and a weight between 100 and 1000 g/m2, the felt having a density between 150 and 1000 g/m 2 and a permeability greater than that of the scrim and between 20 and 250 l/dm 2 /minute at 12 mm of water gauge; and a membrane laminated onto the felt, made of E-PTFE and having a permeability of between 3 and 75 l/dm 2 /minute at 12 mm of water gauge, preferably between 12 and 50 l/dm 2 /minute at 12 mm of water gauge; wherein the filtration material can be pleated using a traditional pleater at room temperature and thenceforth retain its pleats.
  • a process of making a pleatable filtration material comprising felting PTFE fibers onto a pleatable metallic scrim having resistance characteristics at least comparable to that of the PTFE fibers, a permeability of at least 20 l/dm 2 /minute at 12 mm of water gauge and a weight between 100 and 1000 g/m2, until a felt density between 150 and 1000 g/m 2 in addition to the density of the scrim and a permeability greater than that of the scrim and between 20 and 250 l/dm 2 /minute at 12 mm of water gauge are reached; and laminating an E-PTFE membrane having a permeability of between 3 and 75 l/dm 2 /minute at 12 mm of water gauge, preferably between 12 and 50 l/dm 2 /minute at 12 mm of water gauge onto a face of the felted PTFE fibers.
  • a pleated filter bag for use in a bag house dust collector, the filter bag being elongated and comprising a longitudinal hollow center with an open end, and a pleated filter wall transversally circumscribing the hollow center, the pleated filter wall having a felt felted onto an apertured and pleatable scrim and having a permeability lower than a permeability of the scrim and appropriate for filtration applications, and a membrane having a permeability substantially lower than the permeability of the felt and covering the felt on the outer side thereof facing the hollow center, wherein all of the scrim, the felt, and the membrane are resistant to a harsh filtration environment of the dust collector.
  • a filter fabric construction which incorporates a pleatable scrim to the base felt.
  • the pleatability of the scrim takes precedence on the pleatability of the remaining components of the filter fabric, thereby rendering the filter fabric pleatable.
  • This construction, or associated production method can make pleatable a material such as PTFE, which was traditionally known as non-pleatable.
  • a pleatable filtration fabric having an E- PTFE laminated PTFE felt.
  • This filtration fabric is made pleatable while at least substantially maintaining the thermal and chemical resistance characteristics of the PTFE by making the PTFE felt with a pleatable, heat-resistant and chemical-resistant scrim.
  • the pleatability of the metallic scrim takes precedence in the combination and makes the entire material pleatable.
  • pleatable is to be understood in the context of operability in filtration.
  • a pleatable filtration element will retain its pleats for a reasonable lifespan in the context of a normal or recommended use.
  • a felt of polyester with a polyester scrim can be viewed as a non-pleatable fabric, whereas spunbounded polyester, which is denser and suffer, can be viewed as pleatable.
  • Fig. 1 is a perspective view, fragmented, showing an example of a felt having a pleatable scrim.
  • PTFE polytetrafluoroethylene
  • An example of an application where unpleated PTFE-based bags were still used is dust collectors of waste incineration facilities. Incinerated wastes typically contain plastics which emit aggressive chemicals such as HCl, H2SO4, and HF during combustion.
  • PTFE was appreciated for resisting to the combination of high temperatures ( ⁇ 150 to 260 0 C) and aggressive chemicals present in such waste incineration gaseous by-products.
  • the PTFE fabric can be covered by a membrane to get a more efficient degree of filtration.
  • a porous expanded PTFE membrane (E-PTFE) can be used to this end, laminated on the PTFE felt.
  • a type of pleatable scrim which can be used in making a PTFE felt pleatable is a metallic scrim.
  • Fig. 1 shows an exemplary sample of a PTFE felt spunlaced onto a metallic scrim.
  • the metallic scrim is a square steel screen.
  • the metallic scrim is sandwiched between two layers of PTFE felt.
  • the fibers are placed on one side of the scrim, and partially pass through it, to the other side.
  • the right- hand side of the sample is shown pleated.
  • the E-PTFE membrane (not shown in the illustration), can later be laminated onto one face of the PTFE felt with metallic scrim.
  • the PTFE felt can act as a support layer for the E-PTFE membrane which has a permeability substantially lower than the permeability of the felt, hi use, the E-PTFE membrane faces the outside of the filtration bag and determines the relatively low permeability of the filtration material.
  • the felt can thus be used to provide a cushioned support to the membrane, and, in combination with the metallic scrim, gives mechanical resistance to the membrane which acts as the actual "filter” during use but which is not practically usable alone.
  • the metallic scrim additionally provides pleatability to the filtration material because its higher pleatability takes precedence in the assembly.
  • the felt can be made of expanded porous or non-expanded PTFE fibers.
  • the felt can be made by spunlacing the fibers onto the metallic scrim by a water jet - a process commonly referred to as hydro-entanglement. Hydro-entanglement can allow to avoid or reduce damage to the metallic scrim which could result if using conventional needle felting instead.
  • the felt can have a density between 150 and 1000 g/m 2 , preferably between 250 and 700 g/m 2 , and a permeability between 20 and 250 l/dm 2 /minute at 12 mm of water gauge, preferably above 100 l/dm 2 /minute, for example.
  • the metallic scrim can be made of galvanized steel, stainless steel, aluminum, aluminium alloy, bronze, brass, copper, copper-based alloy, nickel, nickel-based alloy, or any suitable metal or alloy, provided it has suitable pleatibility and resistance, and that it is ductile enough to be pleated without breaking.
  • the metal can be a woven mesh, a punched metal sheet or any method that will create a metal sheet with suitable apertures in it.
  • the permeability of the material should be greater than the permeability which is desired of the felt, preferably at least 20 l/dm 2 /minute at 12 mm of water gauge.
  • the weight of the metal scrim can be between 100 and 1000 g/m , preferably between 300 and 700 g/m for example.
  • the felted support layer can be treated with a binder prior to lamination of the membrane, or the binder can be omitted.
  • the fibers of the felt can act in a binding manner in certain applications.
  • the binder can be a fluorinated ethylene propylene copolymer (FEP) or a hexafluoropropylene-tetrafluorethylene copolymer, for example, or any other suitable binder.
  • FEP fluorinated ethylene propylene copolymer
  • the binder can be provided at a concentration of between 25-50 % by weight in a liquid suspension, and be either sprayed on a selected side of the support layer or transferred thereon using a roll.
  • the material can then be heated in an oven at -120 to 240 °C, to evaporate the solvent. After evaporation, the weight of transferred solid binder can represent a relative weight of between 1% and 10 % (relative to the weight of the fabric).
  • the membrane which can be made of commercially available E-PTFE, preferably has a permeability between 3 and 75 l/dm 2 /minute at 12 mm of water gauge, more preferably between 12 and 50 l/dm 2 /minute at 12 mm of water gauge.
  • the membrane can be laminated on the side having the binder at a temperature of 270 °C.
  • PTFE felt for use in applications such as incinerators can have particles of catalyst deposited on the surface or embedded into the PTFE fibers. This can be desirable in a pleatable fabric and typically does not affect pleatability. For example, some catalysts help reducing emissions of dioxin, furan or nitrous oxide from waste incineration.
  • the catalyst typically is typically provided a volume less than 20 % of the volume of the PTFE fibers.
  • examples of catalysts include titanium dioxide (TiO 2 ), iron and cobalt (provided in the form of oxides), nickel, platinum and palladium.
  • Other examples of catalysts include zeolith, copper oxide, tungsten oxide, aluminum oxide, chromium oxide, gold, silver, rhodium etc. If used, the catalyst should be provided in a particles size of less than 10 microns, but can be of any suitable shape, such as spheres, whiskers, plates, flakes, etc.
  • a resulting pleatable filtration material, or fabric can include PTFE fibers spunlaced to a steel scrim, covered by a membrane.
  • a fabric can be pleated using a traditional pleater operating at room temperature.
  • the use of a pleatable metallic scrim can render the use of heated pleater blades unnecessary.
  • PTFE fibers are spunlaced onto a 400 g/m 2 stainless steel scrim by hydro-entanglement. After entangling the total weight is 800 g/m 2 . The permeability of the material at this step is about 200 l/dm 2 /minute. The resulting felted support material is then sprayed with a suspension of FEP particles to add about 25g/m of FEP particles after drying at 150 0 C.
  • the resulting filtration material has a weight of 825 g/m 2 , and a permeability between 15 and 30 l/dm 2 /minute at 12 mm of water gauge, and is pleatable at room temperature.
  • Titanium dioxide particles of less than 10 microns in size are mixed with a PTFE dispersion.
  • the titanium dioxide can correspond to 1-90 % by volume, preferably 25-85 % by volume, for example.
  • the paste is extruded and calendered to form a tape.
  • the tape is slitted along the length, expanded and processed over a rotating pinwheel to form fibers.
  • These fibers with catalyst on the surface are spunlaced onto a 500 g/m2 stainless steel 316 scrim by hydroentanglement. After entangling the total weight is 900 g/m2.
  • the E-PTFE membrane is laminated directly on the surface of the catalytic felt, the fibers acting as the binding agent.
  • the resulting material has a weight of 900 g/m2, a permeability between 15 and 30 l/dni2/min at 12 mm of water gauge and is pleatable at room temperature.

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Abstract

The pleated filter bag, which can be used in a bag-house type dust collector, is elongated and has a longitudinal hollow center with an open end, and a pleated filter wall circumscribing the hollow center. The pleated filter wall has a felt such as PTFE fibers felted onto an apertured and pleatable scrim which can be made of metal, and having a permeability lower than a permeability of the scrim. A membrane of lower-permeability material, such as an E- PTFE membrane, covers the support felt on the outer side of the bag.

Description

FILTER BAG, PLEATABLE FILTRATION MATERIAL THEREFORE, AND PROCESS OF MAKING SAME
FIELD
The specification relates to pleatable materials, or fabrics, for use in filtration, and more particularly for use as pleated "filter bags" in baghouse-type dust collectors, for example.
BACKGROUND
A dust collector is an equipment to remove particles in an industrial fume. Typically the collector contains between hundreds to thousands of cylindrical elements referred to as bags. The bags are made of a filtration fabric that is porous. As the gas flows through, the porous filtration fabric collects particles. The particles can form a cake on the surface after minutes of operation, and the bags are typically cleaned by a reversed jet.
One of the important parameters of the filtration fabric is the filtration efficiency. The efficiency of filtration of bags is related to the total surface area. Typically, if the surface area is increased, then the velocity of gas and particles going through the fabric will be reduced, which decreases the probability of undesired particles going through the fabric and can consequently reduces the particle emissions. Moreover, a higher surface area can reduce the probability of particles getting embedded into the fabric in a manner where they resist the reversed jet, thereby increasing the lifespan of the filter. It is also possible, by increasing the surface area, to increase the capacity of a dust collector. It is thus generally sought to increase the surface area of the bags in dust collectors, where possible.
Typically, pleated bags have a greater surface area than non-pleated bags (i.e. simply cylindrical bags). Using pleated bags instead of non-pleated bags is thus one way of increasing the surface area without necessarily increasing the overall size of the dust collector system. In many cases, replacement of non-pleated bags by pleated bags can increase the surface area by two to three times. Pleated bags can be made using a pleatable material which keeps its shape after pleating. The pleating can be done with a pleating machine. Some pleating machines operate at room temperature.
Alternately, for some materials which require thermosetting to retain their pleats, pleating machines having heating blades are used to fold the fabric and keep pressure on the pleats until the fabric is cooled back to room temperature. Heretofore, such processes have been used with polymers that can be thermally formed and have a relatively small density.
Some materials that are not thermally formable per se can be made so by adding a thermosetting resin. An example of this is fiberglass felt impregnated with phenolic resin. The temperature of blades allow setting of the phenolic resin which subsequently acts to maintain the shape of the pleats. The reaction being irreversible, the pleats subsequently keep their shape even at high temperature.
However, even given the state of the art, some filtration materials could not be pleated by the known means and therefore remained known as being unpleatable. Nevertheless, given some desired characteristics, at least one of these 'unpleatable' filtration materials remained a popular choice for some specific applications despite the fact that it was not available in pleated form. There thus remained a strong need for an equivalent to such 'unpleatable' materials in pleated form due to the many advantages of pleats in filtration. This called for improvement.
SUMMARY
As it will appear from the description below, a filtration material such as a PTFE felt covered by an E-PTFE membrane, which was traditionally known as unpleatable, can now be made pleatable by felting with a pleatable scrim, more particularly a pleatable metallic scrim. There are many metals which are pleatable when provided in apertured sheets, and the pleatability of a metallic scrim can take precedence on the pleatability of both the felted PTFE and the E-PTFE membrane. Felting by hydro-entanglement (spunlacing) can be better suited than neddle-felting when using a metallic scrim.
In accordance with one aspect, there is provided a pleatable filtration material comprising a felt having PTFE fibers felted onto a pleatable metallic scrim, a permeability of at least 20 l/dm2/minute at 12 mm of water gauge and a weight between 100 and 1000 g/m2, the felt having a density between 150 and 1000 g/m2 and a permeability greater than that of the scrim and between 20 and 250 l/dm2/minute at 12 mm of water gauge; and a membrane laminated onto the felt, made of E-PTFE and having a permeability of between 3 and 75 l/dm2/minute at 12 mm of water gauge, preferably between 12 and 50 l/dm2/minute at 12 mm of water gauge; wherein the filtration material can be pleated using a traditional pleater at room temperature and thenceforth retain its pleats.
In accordance with one aspect, there is provided a process of making a pleatable filtration material comprising felting PTFE fibers onto a pleatable metallic scrim having resistance characteristics at least comparable to that of the PTFE fibers, a permeability of at least 20 l/dm2/minute at 12 mm of water gauge and a weight between 100 and 1000 g/m2, until a felt density between 150 and 1000 g/m2 in addition to the density of the scrim and a permeability greater than that of the scrim and between 20 and 250 l/dm2/minute at 12 mm of water gauge are reached; and laminating an E-PTFE membrane having a permeability of between 3 and 75 l/dm2/minute at 12 mm of water gauge, preferably between 12 and 50 l/dm2/minute at 12 mm of water gauge onto a face of the felted PTFE fibers.
In accordance with one aspect, there is provided a pleated filter bag for use in a bag house dust collector, the filter bag being elongated and comprising a longitudinal hollow center with an open end, and a pleated filter wall transversally circumscribing the hollow center, the pleated filter wall having a felt felted onto an apertured and pleatable scrim and having a permeability lower than a permeability of the scrim and appropriate for filtration applications, and a membrane having a permeability substantially lower than the permeability of the felt and covering the felt on the outer side thereof facing the hollow center, wherein all of the scrim, the felt, and the membrane are resistant to a harsh filtration environment of the dust collector.
In accordance with another aspect, there is provided a filter fabric construction which incorporates a pleatable scrim to the base felt. The pleatability of the scrim takes precedence on the pleatability of the remaining components of the filter fabric, thereby rendering the filter fabric pleatable. This construction, or associated production method, can make pleatable a material such as PTFE, which was traditionally known as non-pleatable.
In accordance with another aspect, there is provided a pleatable filtration fabric having an E- PTFE laminated PTFE felt. This filtration fabric is made pleatable while at least substantially maintaining the thermal and chemical resistance characteristics of the PTFE by making the PTFE felt with a pleatable, heat-resistant and chemical-resistant scrim. The pleatability of the metallic scrim takes precedence in the combination and makes the entire material pleatable.
It will be understood that in the instant specification, the expression "pleatable" is to be understood in the context of operability in filtration. A pleatable filtration element will retain its pleats for a reasonable lifespan in the context of a normal or recommended use. For instance, a felt of polyester with a polyester scrim can be viewed as a non-pleatable fabric, whereas spunbounded polyester, which is denser and suffer, can be viewed as pleatable.
DESCRIPTION OF THE FIGURES In the appended figures,
Fig. 1 is a perspective view, fragmented, showing an example of a felt having a pleatable scrim.
DETAILED DESCRIPTION
One example of a material which was still used in unpleated form is polytetrafluoroethylene (PTFE), at least partly because of its exceptional thermal and chemical resistance characteristics which made the only viable choice for some harsh environments. An example of an application where unpleated PTFE-based bags were still used is dust collectors of waste incineration facilities. Incinerated wastes typically contain plastics which emit aggressive chemicals such as HCl, H2SO4, and HF during combustion. PTFE was appreciated for resisting to the combination of high temperatures (~ 150 to 260 0C) and aggressive chemicals present in such waste incineration gaseous by-products. In applications such as waste incineration where tolerated emission levels were quite low, the PTFE fabric can be covered by a membrane to get a more efficient degree of filtration. A porous expanded PTFE membrane (E-PTFE) can be used to this end, laminated on the PTFE felt.
Tests attempting to pleat a PTFE felt (with or without catalyst) with a PTFE scrim failed. After pleating, the shape was not kept in a satisfactory way. Further, adding resins to the PTFE was found inefficient, at least partly due to the lack of adhesion and wetting by many of the tested resins on PTFE fibers.
The mere continued use of non-pleated PTFE filtration bags in dust collectors of applications such as waste incineration facilities, in itself demonstrates the former unavailability of this material in pleated form, considering the strong incentives for using pleated bags instead of cylindrical bags.
As will be detailed below, it will be understood how such materials and others can now be pleatable by felting the fabric onto a pleatable scrim. A type of pleatable scrim which can be used in making a PTFE felt pleatable is a metallic scrim.
Fig. 1 shows an exemplary sample of a PTFE felt spunlaced onto a metallic scrim. In this example, the metallic scrim is a square steel screen. As shown in the cut-out portion on the bottom and left-hand side corner of the sample, the metallic scrim is sandwiched between two layers of PTFE felt. In fact, during hydro-entanglement of the PTFE fibers, the fibers are placed on one side of the scrim, and partially pass through it, to the other side. The right- hand side of the sample is shown pleated. The E-PTFE membrane (not shown in the illustration), can later be laminated onto one face of the PTFE felt with metallic scrim. The PTFE felt can act as a support layer for the E-PTFE membrane which has a permeability substantially lower than the permeability of the felt, hi use, the E-PTFE membrane faces the outside of the filtration bag and determines the relatively low permeability of the filtration material. The felt can thus be used to provide a cushioned support to the membrane, and, in combination with the metallic scrim, gives mechanical resistance to the membrane which acts as the actual "filter" during use but which is not practically usable alone. In fact, in many applications, the stresses which would be imparted to the E-PTFE membrane by the scrim during use if it was adhered directly thereto instead of being supported via felt, would result in an E-PTFE membrane having a very short useful life. The metallic scrim additionally provides pleatability to the filtration material because its higher pleatability takes precedence in the assembly.
The felt can be made of expanded porous or non-expanded PTFE fibers. The felt can be made by spunlacing the fibers onto the metallic scrim by a water jet - a process commonly referred to as hydro-entanglement. Hydro-entanglement can allow to avoid or reduce damage to the metallic scrim which could result if using conventional needle felting instead. The felt can have a density between 150 and 1000 g/m2, preferably between 250 and 700 g/m2, and a permeability between 20 and 250 l/dm2/minute at 12 mm of water gauge, preferably above 100 l/dm2/minute, for example.
The metallic scrim can be made of galvanized steel, stainless steel, aluminum, aluminium alloy, bronze, brass, copper, copper-based alloy, nickel, nickel-based alloy, or any suitable metal or alloy, provided it has suitable pleatibility and resistance, and that it is ductile enough to be pleated without breaking. The metal can be a woven mesh, a punched metal sheet or any method that will create a metal sheet with suitable apertures in it. The permeability of the material should be greater than the permeability which is desired of the felt, preferably at least 20 l/dm2/minute at 12 mm of water gauge. The weight of the metal scrim can be between 100 and 1000 g/m , preferably between 300 and 700 g/m for example. Metallic scrims of various known types of metals can have chemical and temperature resistance characteristics suitable for harsh applications. The felted support layer can be treated with a binder prior to lamination of the membrane, or the binder can be omitted. The fibers of the felt can act in a binding manner in certain applications. If used, the binder can be a fluorinated ethylene propylene copolymer (FEP) or a hexafluoropropylene-tetrafluorethylene copolymer, for example, or any other suitable binder. The binder can be provided at a concentration of between 25-50 % by weight in a liquid suspension, and be either sprayed on a selected side of the support layer or transferred thereon using a roll. The material can then be heated in an oven at -120 to 240 °C, to evaporate the solvent. After evaporation, the weight of transferred solid binder can represent a relative weight of between 1% and 10 % (relative to the weight of the fabric).
The membrane, which can be made of commercially available E-PTFE, preferably has a permeability between 3 and 75 l/dm2/minute at 12 mm of water gauge, more preferably between 12 and 50 l/dm2/minute at 12 mm of water gauge. The membrane can be laminated on the side having the binder at a temperature of 270 °C.
Il will be noted that in some instances, PTFE felt for use in applications such as incinerators can have particles of catalyst deposited on the surface or embedded into the PTFE fibers. This can be desirable in a pleatable fabric and typically does not affect pleatability. For example, some catalysts help reducing emissions of dioxin, furan or nitrous oxide from waste incineration. The catalyst typically is typically provided a volume less than 20 % of the volume of the PTFE fibers. Examples of catalysts include titanium dioxide (TiO2), iron and cobalt (provided in the form of oxides), nickel, platinum and palladium. Other examples of catalysts include zeolith, copper oxide, tungsten oxide, aluminum oxide, chromium oxide, gold, silver, rhodium etc. If used, the catalyst should be provided in a particles size of less than 10 microns, but can be of any suitable shape, such as spheres, whiskers, plates, flakes, etc.
A resulting pleatable filtration material, or fabric, can include PTFE fibers spunlaced to a steel scrim, covered by a membrane. Such a fabric can be pleated using a traditional pleater operating at room temperature. The use of a pleatable metallic scrim can render the use of heated pleater blades unnecessary. An exemplary embodiment thereof is provided below :
Example 1
PTFE fibers are spunlaced onto a 400 g/m2 stainless steel scrim by hydro-entanglement. After entangling the total weight is 800 g/m2. The permeability of the material at this step is about 200 l/dm2/minute. The resulting felted support material is then sprayed with a suspension of FEP particles to add about 25g/m of FEP particles after drying at 150 0C.
Then, an E-PTFE membrane is laminated thereon with the temperature of the FEP particles raised to 270 °C. The resulting filtration material has a weight of 825 g/m2, and a permeability between 15 and 30 l/dm2/minute at 12 mm of water gauge, and is pleatable at room temperature.
Example 2
Titanium dioxide particles of less than 10 microns in size are mixed with a PTFE dispersion. The titanium dioxide can correspond to 1-90 % by volume, preferably 25-85 % by volume, for example. The paste is extruded and calendered to form a tape. The tape is slitted along the length, expanded and processed over a rotating pinwheel to form fibers. These fibers with catalyst on the surface are spunlaced onto a 500 g/m2 stainless steel 316 scrim by hydroentanglement. After entangling the total weight is 900 g/m2. The E-PTFE membrane is laminated directly on the surface of the catalytic felt, the fibers acting as the binding agent. The resulting material has a weight of 900 g/m2, a permeability between 15 and 30 l/dni2/min at 12 mm of water gauge and is pleatable at room temperature.
It is to be understood that above example is given for illustrative purposes only. Alternate embodiments can be realized. For instance, thicker or thinner fabrics can be realized using more or less spunlaced PTFE, and different E-PTFE membranes. The pleatable metallic scrim can be applied to materials other than PTFE. Further, other scrim materials than metals can have similar pleatability and resistance characteristics. The use of a catalyst is optional. Given the above, the scope is indicated by the appended claims.

Claims

WHAT IS CLAIMED IS:
1. A pleatable filtration material comprising a felt having PTFE fibers felted onto a pleatable metallic scrim, a permeability of at least 20 l/dm2/minute at 12 mm of water gauge and a weight between 100 and 1000 g/m2, the felt having a density between 150 and 1000 g/m2 and a permeability suitably greater than that of the scrim and between 20 and 250 l/dm2/minute at 12 mm of water gauge; and a membrane laminated onto the felt, made of E- PTFE and having a permeability of between 3 and 75 l/dm2/minute at 12 mm of water gauge; wherein the filtration material can be pleated at room temperature and thenceforth operably retain its pleats.
2. The pleatable filtration material of claim 1 wherein the PTFE fibers are spunlaced onto the metallic scrim.
3. The pleatable filtration material of claim 1 further comprising particles of catalyst having a size of less than 10 microns, at least one of present on the surface of the PTFE fibers and embedded into the PTFE fibers.
4. The pleatable filtration material of claim 3 wherein the particles of catalyst are selected from the group consisting of titanium dioxide, iron oxide, zeolith, copper oxide, tungsten oxide, aluminum oxide, cobalt oxide, nickel oxide, chromium oxide, palladium, nickel, gold, platinum, silver and rhodium.
5. The pleatable filtration material of claim 1 wherein the membrane has a permeability of between 12 and 50 l/dm2/minute at 12 mm of water gauge.
6. The pleatable filtration material of claim 1 wherein the membrane is laminated directly onto the felt.
7. The pleatable filtration material of claim 1 wherein the membrane is laminated onto the felt via a binder which has resistance characteristics at least comparable to that of the PTFE fibers.
8. The pleatable filtration material of claim 7 wherein the binder is fluorinated ethylene propylene copolymer (FEP) or a hexafiuoropropylene-tetrafluorethylene copolymer.
9. The pleatable filtration material of claim 1 wherein the metal scrim has chemical and thermal resistance characteristics at least comparable to PTFE fibers.
10. A process of making a pleatable filtration material comprising felting PTFE fibers onto a pleatable metallic scrim, a permeability of at least 20 l/dm2/minute at 12 mm of water gauge and a weight between 100 and 1000 g/m2 , until a felt density between 150 and 1000 g/m2 in addition to the density of the scrim and a permeability greater than that of the scrim and between 20 and 250 l/dm2/minute at 12 mm of water gauge are reached; and laminating an E-PTFE membrane having a permeability of between 3 and 75 l/dm2/minute at 12 mm of water gauge onto a face of the felted PTFE fibers.
11. The process of claim 10 wherein the step of felting is done by hydro-entanglement.
12. The process of claim 10, wherein the laminating further comprises applying a binder in liquid suspension in a solvent onto the face of the felted PTFE fibers, and subsequently evaporating the solvent, the relative weight of transferred solid binder being between about 1% and 10%.
13. The process of claim 10, wherein the laminating is done directly onto the face of the felted PTFE fibers.
14. The process of claim 10 further comprising pleating the filtration material at room temperature.
15. A pleated filter bag for use in a bag house dust collector, the filter bag being elongated and comprising a longitudinal hollow center with an open end, and a pleated filter wall circumscribing the hollow center, the pleated filter wall having a felt felted onto an apertured and pleatable scrim and having a permeability lower than a permeability of the scrim and appropriate for filtration, and a membrane having a permeability substantially lower than the permeability of the felt and covering the felt on the outer side thereof facing - l i ¬
the hollow center, wherein all of the scrim, the felt, and the membrane are resistant to a harsh filtration environment of the dust collector.
16. The filter bag of claim 15 wherein the scrim is made of metal.
17. The filter bag of claim 15 or 16 the felt has PTFE fibers and the membrane is made of E- PTFE.
18. The pleatable filtration material of claim 17 wherein particles of catalyst are at least one of present on the surface of the PTFE fibers and embedded into the PTFE fibers.
19. The filter bag of any one of claims 15 to 18 wherein the felt is spunlaced onto the scrim by water jets.
PCT/CA2009/001539 2008-10-27 2009-10-26 Filter bag, pleatable filtration material therefore, and process of making same WO2010048709A1 (en)

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AU2009310577A AU2009310577B2 (en) 2008-10-27 2009-10-26 Filter bag, pleatable filtration material therefore, and process of making same
EP09822935.4A EP2361133B1 (en) 2008-10-27 2009-10-26 Filter bag, pleatable filtration material therefore, and process of making same
KR1020117012216A KR101672309B1 (en) 2008-10-27 2009-10-26 Filter bag, pleatable filtration material therefore, and process of making same
US13/126,130 US8728401B2 (en) 2008-10-27 2009-10-26 Filter bag, pleatable filtration material therefore, and process of making same
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US20110206564A1 (en) 2011-08-25
KR101672309B1 (en) 2016-11-03
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EP2361133A4 (en) 2014-04-23
US8728401B2 (en) 2014-05-20
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AU2009310577B2 (en) 2016-03-10
US20120034134A2 (en) 2012-02-09

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