Washable filter media

Abstract

To provide: a cleanable filter medium which is robust enough to survive several cleaning cycles while maintaining excellent filtration properties, such as filter efficiency, dust holding capacity and energy efficiency; and a method for manufacturing the same.SOLUTION: The filter medium comprises at least one textile layer being a nonwoven fabric of synthetic, organic polymer fibers. The nonwoven fabric has an embossed pattern. The nonwoven fabric has a thickness D at the non-embossed area, and a thickness d at the embossed area. The ratio d / D is a compression factor CF, where the compression factor CF is in the range 0.2≤CF≤0.5.SELECTED DRAWING: Figure 2a

Description

[Technical Field]

[0001] The present invention relates to a washable three-dimensional filter medium, a method for manufacturing the filter, and a method for using the filter. [Background technology]

[0002] The use of filters has long been known for a variety of applications. Air filters are used, for example, in the automotive industry, air conditioning systems, vehicle cabins, pollen, cleanrooms, and households. Furthermore, filters have also been used for many years to filter liquid media. Examples of these include oil filters and hydraulic filters.

[0003] Filter media are described, for example, in Patent Documents 1, 2, 3, and 4.

[0004] Filters are adapted to achieve sufficient filtration efficiency and service life according to the application. Removing solids from liquid and / or gaseous fluids is the most common field of filtration. Here, typically, liquid and / or gaseous inflows containing such solid particles cannot pass through the filter's grid structure, leading to clogging of the filter media over time. Clogging causes a pressure drop, meaning that the pressure must be increased to allow the same volume to pass through the filter, resulting in higher energy consumption. Therefore, the filter needs to be cleaned by replacing it with a new one or by removing the filtered material from the filter. Since all such operations are time-consuming and costly, improved washable filter media are desired. Such washable filter media are typically cleaned by removing filtered solids from the filter using a typically pulsed pressurized filter fluid, by simply reversing the flow direction of the filtered fluid. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] European Patent Application Publication No. 0878226 [Patent Document 2] European Patent Application Publication No. 1134013 [Patent Document 3] German Patent Application Publication No. 2000139245 [Patent Document 4] European Patent Application Publication No. 0980700 [Overview of the project] [Problems that the invention aims to solve]

[0006] The inventors have found that a washable filter media can be provided that is robust enough to withstand several washing cycles while maintaining excellent filtration characteristics such as filtration efficiency, dust retention capacity, and energy efficiency. [Means for solving the problem]

[0007] Therefore, the subject of the present invention is a filter material, a) comprising at least one textile layer (layer 1) which is a nonwoven fabric of synthetic organic polymer fibers, a1) The nonwoven fabric is 50 g / m² 2 ~400g / m 2 It has a weight per unit area, a2) The fibers of the nonwoven fabric have a fineness in the range of 0.5 dtex to 15 dtex. a3) The nonwoven fabric is compacted by a thermoplastic binder and / or mechanical means, provided that the nonwoven fabric is not compacted by needling and / or water-jet needling. a4) The nonwoven fabric has an embossed pattern, and the nonwoven fabric has a density of at least 50 l / m 2 seconds, preferably 100 l / m 2 From seconds to 2000 l / m 2 It has breathability for seconds, a5) The non-woven fabric has an embossing pattern, and the surface area of the embossing pattern of the non-woven fabric is 7% to 30% of the total surface area of the non-woven fabric. a6) The surface area of each individual embossing pattern of the non-woven fabric is 0.4 mm 2 ~5.6 mm 2 and has a surface area of a7) The non-woven fabric has a thickness D in the unembossed area and a thickness d in the embossed area, and the ratio d / D is the compression coefficient CF. The compression coefficient CF is within the range of 0.2 ≤ CF ≤ 0.5, and it is a filter filter medium.

Brief Description of the Drawings

[0008] [Figure 1] It is a graph of the residual pressure drop according to the VDI 3926 test procedure for the filter of the present invention and the filter medium of the prior art. [Figure 2a] It is a schematic diagram of the relationship between the thickness D and the thickness d for an embodiment of the present invention. [Figure 2b] It is a schematic diagram of the flank angle for an embodiment of the present invention. [Figure 3] It is a schematic diagram of the embossing pattern for an embodiment of the present invention.

Modes for Carrying Out the Invention

[0009] Non-woven fabric (layer 1) The textile layer used according to the present invention is preferably a non-woven fabric of synthetic organic polymer fibers that can be pleated.

[0010] The non-woven fabric may be composed of various synthetic organic polymer fibers from various polymers or various polymer classes. Furthermore, the non-woven fabric itself may be configured in a multi-layered manner. Here, the individual layers within the non-woven fabric may differ in terms of various selected synthetic polymer fibers and / or may have various fiber diameters, but such parameters are within the given range for the non-woven fabric.

[0011] The nonwoven fabric is a wet-laid nonwoven fabric, a dry-laid nonwoven fabric, or a spunbond nonwoven fabric, and the nonwoven fabric is compacted by a thermoplastic binder and / or mechanical means, provided that the nonwoven fabric is not compacted by needling and / or water-jet needling. Preferably, the nonwoven fabric is compacted by a thermoplastic binder alone. Preferably, the nonwoven fabric is a short-fiber nonwoven fabric and / or a spunbond nonwoven fabric. Spunbond nonwoven fabrics are generally simply called spunbond and are produced by randomly depositing freshly melt-spun filaments. The filaments are continuous synthetic fibers composed of melt-spun polymer material.

[0012] Suitable synthetic organic polymer materials include, for example, thermoplastic resins, preferably polyamides such as polyhexamethylene-diadipamide, polycaprolactam, aromatic polyamides or partially aromatic polyamides ("aramids"), aliphatic polyamides such as nylon, partially aromatic polyesters or fully aromatic polyesters, aliphatic polyesters, polycarbonate (PC), polyphenylene sulfide (PPS), polyphenylene oxide (PPO), polystyrene (PS), polyvinylcarbazole (PVK), polyacetal (POM), polymers containing ether and keto groups such as polyaryl ethers, polyaryl sulfones, polyethersulfones, polyether ketones (PEK) and polyether ether ketones (PEEK), polyolefins such as polyethylene or polypropylene, or polybenzimidazoles. Particularly preferred are polyesters, such as polyethylene or polypropylene, or aromatic polyamides or partially aromatic polyamides ("aramids"), such as nylon, or aliphatic polyamides.

[0013] Spunbond nonwoven fabrics are preferably composed of melt-spun polyester. The polyester material can, in principle, be any known type suitable for fiber production. Such polyesters consist mainly of components obtained from aliphatic dicarboxylic acids or aromatic dicarboxylic acids and aliphatic diols. Commonly used aromatic dicarboxylic acid components are the divalent residues of benzenedicarboxylic acids, particularly terephthalic acid and isophthalic acid, and commonly used diols have 2 to 4 carbon atoms, in which case ethylene glycol is particularly suitable. Spunbond fabrics consisting of at least 85 mol% polyethylene terephthalate are particularly advantageous. The remaining 15 mol% are formed by dicarboxylic acid and glycol portions that act as so-called modifiers, allowing those skilled in the art to have a special effect on the physical and chemical properties of the filaments produced. Examples of such dicarboxylic acid units include residues of isophthalic acid or aliphatic dicarboxylic acids such as glutaric acid, adipic acid, and sebacic acid. Examples of denaturing diol residues include long-chain diols such as propanediol or butanediol, diethylene glycol or triethylene glycol, or, if present, small amounts of polyglycol having a molecular weight of approximately 500 to 2000.

[0014] Polyesters containing at least 95 mol% polyethylene terephthalate (PET), particularly polyesters composed of unmodified PET, are especially preferred.

[0015] The polyester contained in the spunbond nonwoven fabric preferably has a molecular weight corresponding to an intrinsic viscosity (IV) of 0.6 to 1.4, as measured in a solution of 1 g of the polymer in 100 ml of dichloroacetic acid at 25°C.

[0016] In one embodiment of the present invention, a nonwoven fabric, particularly a spunbond nonwoven fabric, is compacted with a melt-fusing binder to obtain a nonwoven fabric compacted with a melt-fusing binder, i.e., compaction is carried out with a thermoplastic binder, preferably in fibrous form. Thus, the nonwoven fabric compacted with a melt-fusing binder contains carrier fibers and hot-melt adhesive fibers. The carrier fibers and hot-melt adhesive fibers can be obtained from any thermoplastic fiber-forming polymer, and the carrier fibers can further be obtained from a non-meltable fiber-forming polymer. Such spunbond fabrics compacted with a melt-fusing binder are basically described, for example, in European Patent Application Publication No. 0,446,822 and European Patent Application Publication No. 0,590,629.

[0017] Examples of polymers from which carrier fibers can be obtained include polyolefins such as polyacrylonitrile, polyethylene, or polypropylene; polyamides that are primarily (primarily) aliphatic, such as nylon 6.6; copolymers containing aromatic m-diamine moieties to improve solubility; or polyamides (aramids) such as poly-(m-phenylene isophthalate); primarily aromatic polyesters such as poly-(p-hydroxybenzoate); or preferably primarily aliphatic polyesters such as polyethylene terephthalate.

[0018] The relative proportion of the two types of fibers can be selected within a wide range, as long as the proportion of hot-melt adhesive fibers is sufficient to bond the carrier fibers to the hot-melt adhesive fibers, thereby giving the nonwoven fabric sufficient strength for its intended application, while ensuring the required breathability. The proportion of hot-melt derived from hot-melt fibers in the nonwoven fabric is typically less than 50% by weight (based on the weight of the nonwoven fabric).

[0019] Modified polyesters having a melting point 10°C to 50°C, preferably 30°C to 50°C lower than that of the raw materials for nonwoven fabrics, are particularly suitable as hot-melt adhesives. Examples of such hot-melt adhesives are polypropylene, polybutylene terephthalate, or polyethylene terephthalate modified by condensation of long-chain diols and / or isophthalic acid or aliphatic dicarboxylic acid.

[0020] The hot-melt adhesive is preferably incorporated into the nonwoven fabric in a fibrous form.

[0021] The carrier fibers and hot-melt adhesive fibers are preferably composed of one polymer class. This means that all the fibers used are selected from one material class, so these materials can be easily recycled after the nonwoven fabric has been used. If the carrier fibers are, for example, polyester, the selected hot-melt adhesive fibers are similarly polyester or a mixture of polyesters in the form of a binary fiber having, for example, PET as the core and a low-melting-point polyethylene terephthalate copolymer as the sheath. However, binary fibers composed of different polymers are also possible. Examples of these are binary fibers of polyester and polyamide (core / sheath).

[0022] The filament fineness of the carrier fiber and the hot melt adhesive fiber can be selected within the above limits.

[0023] The filaments or short fibers constituting the nonwoven fabric may have a substantially circular cross-section or other shapes such as dumbbell-shaped, kidney-shaped, triangular, trefoil, or compound-lobed cross-sections. Hollow fibers and two-component or multi-component fibers may also be used. Furthermore, hot-melt adhesive fibers may be used in the form of two-component or multi-component fibers.

[0024] The fibers forming the nonwoven fabric may be modified with conventional additives, such as antistatic agents like carbon black or additives that enable static charge. Furthermore, the fibers may contain antimicrobial materials.

[0025] The weight per unit area of the nonwoven fabric is 50 g / m 2 to 400 g / m 2 and preferably 80 g / m 2 to 300 g / m 2 and particularly 100 g / m 2 to 250 g / m 2 The weight per unit area is measured in accordance with DIN EN ISO 29073-1 (1992-08).

[0026] In another embodiment of the present invention, the nonwoven fabric is pre-compacted by mechanical means such as hot rollers or calendering, provided that the nonwoven fabric is not compacted by needle punching and / or hydraulic needle punching (water jet needle punching).

[0027] For pre-compaction, a fusible binder-containing nonwoven fabric containing binder fibers in addition to carrier fibers is thermally pre-compacted by hot rollers, calendering or in a furnace as is known per se. The fibers may have a two-component structure (e.g., core / shell) where the sheath is the binder polymer.

[0028] The nonwoven fabric compacted by a thermoplastic binder and / or mechanical means such as calendering may further contain a chemical binder, and such a chemical binder cures by a curing reaction and typically such a chemical binder is an acrylate-based binder and / or a styrene-based binder and / or a starch-based binder and / or a phenol-based binder and / or a latex-based binder. When present, such a chemical binder is present in an amount of 0.1% to 30% by weight (based on the total weight of the nonwoven fabric).

[0029] The fineness of individual fibers of the synthetic organic polymer forming the nonwoven fabric is between 0.5 dtex and 15 dtex, preferably between 1 dtex and 10 dtex. The fineness is typically determined during the manufacturing of the fibers. The fineness of the fibers can be measured according to DIN EN ISO 1973:1995-12 (vibroscope method).

[0030] Preferably, when the nonwoven fabric is made of short fibers of a synthetic organic polymer, such short fibers have a length between 5 mm and 100 mm, preferably between 10 mm and 80 mm.

[0031] The nonwoven fabric in the filter according to the present invention has a density of at least 50 l / m², measured in accordance with DIN EN ISO 9237:1995-12. 2 seconds, preferably 100 l / m 2 From seconds to 2000 l / m 2 For seconds, a comfortable 150 l / m² 2 sec~1000l / m 2 It has breathability within a range of seconds. Such a nonwoven fabric in a filter has an embossed pattern having a compression coefficient according to the present invention.

[0032] As described above, the nonwoven fabric may itself be constructed in a multilayer structure. Here, the individual layers within the nonwoven fabric may differ in terms of various selected synthetic polymer fibers and / or may have various fiber diameters, but such parameters are within a given range for the nonwoven fabric. Thus, in the case of a nonwoven fabric having a multilayer structure, there are at least 2 to 10 layers, preferably 2 to 4 layers. Preferably, the fineness of the fibers increases in one direction in the thickness direction of the nonwoven fabric, so that a fineness gradient is formed within the fineness range described above.

[0033] The nonwoven fabric, particularly the spunbond nonwoven fabric, in the filter material according to the present invention has a thickness D of 0.4 mm to 0.95 mm, preferably 0.45 mm to 0.8 mm, in the unembossed area. The above-mentioned thickness D also includes nonwoven fabrics having a multilayer structure.

[0034] The nonwoven fabric, particularly the spunbond nonwoven fabric, in the filter material according to the present invention has a thickness D in the unembossed region and a thickness d in the embossed region, where the ratio d / D is the compression coefficient CF, and the compression coefficient CF is in the range of 0.2 ≤ CF ≤ 0.5, preferably in the range of 0.25 ≤ CF ≤ 0.4. The thicknesses D and d are measured by microscopic optical methods focusing on the cross-sections of both the embossed and unembossed regions.

[0035] The nonwoven fabric in the filter material according to the present invention, particularly the spunbond nonwoven fabric, has a surface area of ​​an embossed pattern that is 7% to 30% of the total surface area of ​​the nonwoven fabric.

[0036] According to the present invention, the surface area of ​​each individual embossed pattern of the nonwoven fabric is 0.4 mm². 2 ~5.6mm 2 It has a surface area of

[0037] Generally, the shape of individual embossed patterns is not limited, but for practical reasons, individual embossed patterns are angular and / or circular and / or elliptical, with a length-to-width ratio of 1:1 to 1:8.

[0038] Embossed patterns are created by one or more embossing rolls having the desired pattern on their surface. Typically, the embossing rolls are heated to a temperature between 80°C and 250°C.

[0039] The embossed pattern is created by one or more embossing rolls that compress the nonwoven fabric with a linear pressure of at least 13 daN / cm. Suitable embossing rolls are provided within the calendering apparatus.

[0040] The mechanism for producing a nonwoven fabric having an embossed pattern according to the present invention can be achieved by a calendering apparatus with at least two rollers, in which two opposing rolls are pressed against each other with a linear pressure of at least 13 daN / cm, and one roll of the calendering apparatus has a smooth surface, while the other roll of the calendering apparatus has a structured surface corresponding to the desired embossed pattern. Typically, the two opposing rolls are heated to a temperature between 80°C and 250°C.

[0041] The structured areas of the roller that protrude from the surface compress the nonwoven fabric to a thickness d, while the areas of the roller that do not protrude compress the nonwoven fabric to a thickness D, thus resulting in a compression coefficient CF, which is a ratio d / D, where the compression coefficient CF is in the range of 0.2 ≤ CF ≤ 0.5, and preferably in the range of 0.25 ≤ CF ≤ 0.4. This embodiment is shown in Figure 2a.

[0042] In one embodiment of the present invention, the structured roll region protruding from the surface of the roller preferably has a flank angle of 18 to 30 degrees, such a flank angle resulting in an embossed pattern, while the mechanical properties of the nonwoven fabric remain robust, taking into account the filter material which may be washed between wash cycles. This embodiment is shown by Figure 2b.

[0043] Nonwoven fabrics according to the present invention, particularly spunbond nonwoven fabrics, having an embossed pattern surface area of ​​7% to 30% of the total surface area of ​​the nonwoven fabric, provide a larger active area for filtration compared to nonwoven fabrics without such an embossed surface area.

[0044] Embossed patterns can be produced by embossing in one direction (x-direction) or in both directions (x-direction and y-direction). Embossed patterns may be randomly distributed or regular. An example of an embossed pattern is shown in Figure 3.

[0045] As explained above, the embossed pattern present in the nonwoven fabric of the present invention can be produced by one or more calender rolls, in which case the one or more rolls produce the embossed pattern.

[0046] The embossing on the nonwoven filter media provides a more active filter surface for a given volumetric gas / airflow, reducing local flow velocities within the filter media. This increases filtration efficiency and improves dust retention capacity.

[0047] The filter media according to the present invention is a so-called washable filter media that can be cleaned by simply reversing the flow direction of the filter fluid, typically by removing filtered solids from the filter using a pulsed pressurized filter fluid. Surprisingly, the filter media according to the present invention exhibits excellent washing behavior.

[0048] During a cleaning cycle, most of the material filtered from the filter media is removed, primarily from the surface of the filter media. However, it is impossible to completely remove the filtered material. Filter media with a large dust-holding capacity, in particular, suffer from incomplete removal of filtered material from the body / volume of the filter media. This results in a gradual increase in pressure drop at the start of each cleaning cycle, limiting the number of such cleaning cycles. The filter media of the present invention significantly improves the number of possible cleaning cycles.

[0049] Figure 1 shows the residual pressure drop according to the VDI 3926 test procedure for three filter media fabricated according to the present invention (FI180036, FI180040, and FI180044) and one prior art filter media for comparison (778 / 250 standard). Table 1 contains further information on the filter media described above. As can be seen, the filter media of the present invention already show a reduction in pressure drop during the first 30 wash cycles. Even after 10,000 wash cycles ("aging", not shown), the performance improvement of the filter media of the present invention continues.

[0050] ISO 12103-1 A2 fine test dust at 5 g / m² 3 The filter media was tested using the specified concentration. The air-to-fabric ratio was 120 m 3 / (m 2 h) was the result. The first 30 cycles and the last 30 cycles were performed with cleaning after the pressure drop reached 10 mbar. Aging (10,000 cycles) was performed with cleaning every 5 seconds. Cleaning was performed using pressurized air (tank pressure: 5 bar) with a valve open time of 60 milliseconds.

[0051] [Table 1]

[0052] FI180036, FI180040, and FI180044 are spunbond nonwoven fabrics using core-sheath fibers. The core polymer is PET (polyethylene terephthalate), and the sheath is modified PET with a lower melting point than the core PET.

[0053] FI180036, FI180040, and FI180044 are heat-bonded spunbond nonwoven fabrics that are not needled and do not contain chemical binders.

[0054] The reference material is a heat-bonded spunbond nonwoven fabric.

[0055] Manufacturing of filter media The nonwoven fabric layer according to the present invention is manufactured by known methods available to those skilled in the art. Suitable methods are shown, for example, in Handbook of Nonwovens, CRC Press, 2007, and the formation of nonwoven fabrics such as spunbond nonwovens would likewise be common knowledge to those skilled in the art.

[0056] The nonwoven fabric is either formed linearly or supplied in a roll. In the linear method, the nonwoven fabric may be pre-compacted. Pre-compacting is performed by using a hot roller or calender, as known to those skilled in the art. The nonwoven fabric, whether formed linearly or supplied in a roll, is fed into an embossing calender to give the embossed pattern according to the present invention. Embossing of nonwoven materials is also known in itself, but the special embossing of the present invention brings advantages to the present invention.

[0057] As already mentioned above, the embossed pattern is produced at atmospheric pressure using the heated rollers of the calender, but the method may be carried out with or without heat and / or pressure. The embossed pattern may be a continuous pattern across the entire filter medium (Figure 3), or a repeating pattern of discrete indentations such as rectangles, circles, other regular polygons, depressions, or other unconventional shapes (Figure 3).

[0058] The filter media according to the present invention is used in filter systems for air / gas filtration and liquid filtration, particularly in the automotive industry, air conditioning systems, vehicle interior filters, pollen filters, cleanroom filters, household filters, and oil filters and hydraulic filters, to remove solids from air / gas and liquids.

[0059] Therefore, the subject matter of the present invention is also a filter system and filter cartridge including a filter material according to the present invention.

[0060] The filter material according to the present invention can be formed into any number of filter configurations.

[0061] Further applications of the filter according to the present invention include mounting panels and sound-absorbing panels.

Claims

1. It is a filter material, a) comprising at least one textile layer (layer 1) which is a nonwoven fabric having a multilayer structure of synthetic organic polymer fibers, a1) The nonwoven fabric has a density of 50 g / m². ２ ~400g / m ２ It has a weight per unit area, a2) The individual fiber thickness of the fibers forming the nonwoven fabric is between 0.5 dtex and 15 dtex. a3) The nonwoven fabric is compacted by a thermoplastic binder and / or mechanical means, provided that the nonwoven fabric is not compacted by needling and / or water-jet needling. a4) The nonwoven fabric has an embossed pattern, and the nonwoven fabric has a density of at least 50 l / m ２ It has breathability in seconds, a5) The nonwoven fabric has an embossed pattern, and the surface area of ​​the embossed pattern of the nonwoven fabric is 7% to 30% of the total surface area of ​​the nonwoven fabric. a6) The surface area of ​​each individual embossed pattern of the nonwoven fabric is 0.4 mm². ２ ~5.6mm ２ It has a surface area, a7) The nonwoven fabric has a thickness D in the unembossed region and a thickness d in the embossed region, and the ratio d / D is the compression coefficient CF, and the compression coefficient CF is in the range of 0.2 ≤ CF ≤ 0.

5. a8) The multilayer structure of the nonwoven fabric is such that the fineness of the fibers within each layer increases in one direction relative to the thickness of the nonwoven fabric. Filter media.

2. The filter material according to claim 1, wherein the individual layers within the nonwoven fabric differ in terms of synthetic organic polymer fibers and / or fiber diameter.

3. The filter material according to claim 1 or 2, wherein the nonwoven fabric is a wet-laid nonwoven fabric, a dry-laid nonwoven fabric, or a spunbond nonwoven fabric, and the nonwoven fabric is compacted by a thermoplastic binder and / or mechanical means, provided that the nonwoven fabric is not compacted by needling and / or water-jet needling.

4. The filter material according to claim 1, wherein the nonwoven fabric is a spunbond nonwoven fabric, and the spunbond nonwoven fabric is compacted with a melt-bondable binder to obtain a nonwoven fabric compacted with a melt-bondable binder.

5. The weight per unit area of ​​the nonwoven fabric is 80 g / m². ２ From 300g / m ２ The filter material according to claim 1, which is between [a certain range].

6. The weight per unit area of the non-woven fabric is from 100 g / m ２ to 250 g / m ２ The filter medium according to claim 1, wherein the filter medium is in this range.

7. The filter material according to claim 1, wherein the fineness of each synthetic organic polymer fiber forming the nonwoven fabric is between 1 dtex and 10 dtex.

8. The nonwoven fabric in the filter media is 100 l / m ２ From seconds to 2000 l / min ２ The filter material according to claim 1, having air permeability within a range of seconds.

9. The nonwoven fabric in the filter material is 150 l / m ２ From seconds to 1000 l / min ２ The filter material according to claim 1, having air permeability within a range of seconds.

10. The filter material according to claim 1, wherein the nonwoven fabric in the filter material has a thickness D of 0.4 mm to 0.95 mm in the area that is not embossed.

11. The filter material according to claim 10, wherein the nonwoven fabric is a spunbond nonwoven fabric.

12. The filter material according to claim 1, wherein the compression coefficient CF is within the range of 0.25 ≤ CF ≤ 0.

4.

13. The filter material according to claim 1, wherein the nonwoven fabric in the filter material having a surface area of ​​an embossed pattern that is 7% to 30% of the total surface area of ​​the nonwoven fabric is a spunbond nonwoven fabric.

14. The surface area of ​​each individual embossed pattern of the nonwoven fabric is 0.4 mm². ２ ~5.6mm ２ A filter material according to claim 1, having a surface area.

15. Use of the filter material according to claim 1 in the filtration of gas or liquid.

16. A filter module comprising a housing and at least one filter medium as described in claim 1.

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