Method for producing a filter element
Patent Information
- Application Number
- EP2023706004
- Authority / Receiving Office
- EP · EP
- Patent Type
- Applications
- Current Assignee / Owner
- Priority Date
- 2022-02-21
- Filing Date
- 2023-02-17
- Publication Date
- 2025-01-01
AI Technical Summary
The production of filter elements for electrostatic precipitators faces challenges in large-scale manufacturing due to issues like short circuits between conductive layers, mechanical stress, and reduced filtration efficiency over time, particularly when using thermoplastic nonwoven materials, which are prone to deformation and fusion during cutting processes.
A method involving the production of filter elements with two electrically conductive layers separated by an insulating material, where the layers are coated with conductive materials to maintain polarization and separation efficiency, and are merged and separated in a way that avoids direct contact during the manufacturing process, using techniques like selective coating and non-cutting separation methods to prevent short circuits.
This method enables the production of filter elements with improved separation efficiency and mechanical resilience, reducing waste and production costs, while maintaining performance over the filter's service life and ensuring high operational reliability with minimal delamination.
Smart Images
Figure 1.1
Abstract
Description
[0001] Method for producing a filter element
[0002] Description
[0003] The invention relates to a method for producing a filter element and a corresponding filter element, as well as a filter comprising the filter element. Furthermore, a device for carrying out the method is disclosed. Modern filtration technology today offers numerous efficient alternatives and further developments to the traditional methods for separating unwanted components from fluid streams. These methods are generally based on essentially mechanical separation, usually on a partially permeable filter element, which may, for example, be made of a porous material.
[0004] One of these developments, which is used particularly for gas purification, is so-called electrostatic precipitation, whereby the devices used are also known as electrostatic precipitators. In these electrostatic precipitators, the particles to be removed are first ionized by an electrode and then deposited on an oppositely charged collecting electrode. Such electrostatic precipitators are used primarily in industrial plants.
[0005] However, other requirements are placed on the performance characteristics of cabin air filters, particularly for use in vehicles, whereby, for example, the reliable separation of pollen and / or particulate matter and / or odors and / or exhaust gases is also desired.
[0006] To meet these requirements for cabin air filters, the concept of electrostatic separation, which in many cases is not strictly speaking filtration, was combined with mechanical separation processes to achieve high-performance filters. Due to the mostly intrinsic electrostatic charge of many filter materials used in filtration, for example typical nonwoven materials, especially so-called electret materials, the separation efficiency of filters can in many cases be significantly increased by combining them with an ionization device. However, with such filter arrangements, it has been observed that the separation efficiency can decrease over the service life of the filter arrangement, which is often attributed to a reduction in the electrostatic charge in the filter material over time.
[0007] To solve this problem, filter elements have been proposed that have two electrically conductive layers separated from each other by an insulating material within the layered material. These layers can be used to polarize the filter material by applying a voltage through the creation of an electric field. In combination with an ionization device, this polarization enables efficient separation, which can advantageously usually be maintained over the entire service life of the filter element. Examples of corresponding filter elements and further background information on the basic technology are disclosed, for example, in WO 2007 / 135232 A1 or EP 3 448 540 B1.
[0008] Despite the potentially advantageous properties, the production of corresponding polarizable filter elements for electrostatic precipitators proves to be very challenging in practice. To ensure proper function, contact between the two layers acting as electrodes in the filter element must be prevented. This is often made difficult by the fact that the layered filter elements usually have to be folded for use to create a so-called pleated filter element. The application of the necessary electrodes, via which the voltage can be applied to the two layers acting as electrodes in the filter element, also presents a challenge.
[0009] The problems described above are particularly serious in the area of large-scale production of such filter elements, i.e. in the area of mass production, as is particularly necessary for supplying the automotive industry. When attempting to implement this on a large scale, it is particularly disadvantageous that for the continuous production of filter elements from web-shaped starting materials, which, with regard to the achievable
[0010] Production capacities and process control would be preferred, inevitably a separation of the filter elements from the strand or web-shaped
[0011] layer structure. However, this so-called cutting of the web-like layer structure to length results in mechanical and / or thermal stress on the material in the cutting area due to the processes used, such as cutting, hot cutting or ultrasonic welding, which can lead, for example, to compression of the filter medium and / or to fusion of the layers. Due to this circumstance, there is a high probability that a short circuit will occur between the conductive layers during the large-scale production of such filter elements or that such a short circuit will occur as a result of the stress experienced later in use. However, a high level of rejects in production or a high failure rate in use are often exclusion criteria for applications in the automotive sector, for example, since vehicle manufacturers are typically very cost-sensitive and the industry is characterized by high quality expectations.To the best of the inventors’ knowledge, the state of the art also lacks solutions for the large-scale production of corresponding filter elements.
[0012] The problem of unwanted contacting of the conductive layers described above arises in particular when the conductive layers are to be formed using coated nonwovens made of, mostly thermoplastic, plastic, which, according to the inventors' findings, is particularly advantageous with regard to the weight of the filter element, the manufacturing costs and the achievable filter performance, since these materials are easily deformable mechanically and often comprise thermoplastic materials.
[0013] The primary object of the present invention was to eliminate or at least mitigate the disadvantages of the prior art described above.
[0014] In particular, it was an object of the present invention to provide a process for producing filter elements for use in electrostatic precipitators, with which corresponding filter elements can also be produced on an industrial scale, in particular in the context of continuous or at least semi-continuous processes.
[0015] In particular, however, it was also an object of the present invention to provide a filter element for use in electrostatic precipitators which is particularly efficient and at the same time mechanically very resilient and with which, in combination with an ionization device in filters, particularly good separation performance can be achieved.
[0016] In the interplay of the two objects described above, a particular object of the present invention was to optimally match the advantageous process to be specified with the advantageous filter elements to be specified, and vice versa. It was therefore an object of the present invention to resolve the conflicting objectives of purely optimizing the separation efficiency and manufacturability in large-scale industrial processes for the filter elements to be specified, while simultaneously designing the process to be specified in such a way that it is compatible with the technical specifications resulting from the specific design of the filter elements to be specified.
[0017] It was a further object of the present invention that the method to be specified should be as time- and cost-efficient as possible and should ideally ensure a high level of operational reliability, desirably while simultaneously producing little offcuts and other waste.
[0018] It was a supplementary object of the present invention that the filter elements to be specified should be particularly mechanically resilient and should not exhibit any undesirable delamination during production, in particular during folding, but also during subsequent operation in the vehicle. In this respect, it was a further object of the present invention that the filter elements to be specified should have an extended replacement interval compared to the prior art, wherein, in particular, the filter performance with regard to particles should ideally remain largely constant until the end of the replacement interval. Furthermore, it was a supplementary object that the filter elements to be specified should be particularly light and thin in order to thereby achieve space and weight savings.
[0019] A secondary object of the present invention was to provide a filter comprising the filter element to be specified. Furthermore, a secondary object of the present invention was to provide a device suitable for carrying out the method according to the invention.
[0020] The above-mentioned objects are achieved by the subject matter of the invention as defined in the claims. Preferred embodiments of the invention emerge from the subclaims and the following statements.
[0021] Such embodiments, which are referred to as preferred below, are combined in particularly preferred embodiments with features of other embodiments referred to as preferred. Combinations of two or more of the embodiments referred to as particularly preferred below are therefore very particularly preferred. Likewise preferred are embodiments in which a feature of an embodiment referred to as preferred to any extent is combined with one or more further features of other embodiments referred to as preferred to any extent. Features of preferred filter elements, filters and devices emerge from the features of preferred methods. The invention relates to a method for producing a filter element, in particular for use in electrostatic precipitators, comprising the method steps: a) producing or providing a flat, web-shaped first medium,containing a first carrier layer comprising a first nonwoven fabric coated at least in sections with an electrically conductive material, and producing or providing a flat, web-shaped second medium containing a second carrier layer comprising a second nonwoven fabric coated at least in sections with an electrically conductive material, wherein the first medium comprises a first filter layer arrangement connected to the first carrier layer, and / or wherein the second medium comprises a second filter layer arrangement connected to the second carrier layer, b) combining the first medium with the second medium to obtain a web-shaped layer composite, wherein the combining takes place such that the first filter layer arrangement and / or the second filter layer arrangement are arranged at least in sections between the first carrier layer and the second carrier layer,and c) separating a partial section of the web-shaped layer composite to obtain the filter element, comprising a part of the first carrier layer and the second carrier layer as well as the first filter layer arrangement and / or the second filter layer arrangement, wherein the joining in method step b) comprises one of the following steps: b1) applying the web-shaped second medium to the web-shaped first medium, wherein the second carrier layer comprises a plurality of coating regions spaced apart from one another along the web direction of the layer composite, in which the second nonwoven fabric is coated with the electrically conductive material, or b2) dividing the web-shaped second medium to obtain a plurality of partial regions, wherein the joining takes place such that the partial regions are spaced apart from one another along the web direction of the layer composite,wherein the second nonwoven fabric of the second carrier layer is coated at least in sections with the electrically conductive material in the partial regions, and wherein the separation of the partial section from the web-shaped layer composite in process step c) is carried out in such a way that the separation line runs between two adjacent coating regions or two adjacent partial regions.
[0022] The method according to the invention serves to produce filter elements whose design enables the application of an electrical voltage to cause a distribution of the electrical charge in the filter element (polarization) and which consequently have an improved separation effect on charged particles, such as those that can be generated, in particular, by an ionization device. In other words, the filter element is thus particularly designed to cause or promote the separation of electrically charged particles, in particular ionized particles, upon application of an electrical voltage to the first carrier layer and the second carrier layer, in particular to the electrically conductively coated region of the first carrier layer and the second carrier layer.
[0023] The performance of the filter elements produced using the method according to the invention is particularly evident in the field of automotive applications. Accordingly, a method according to the invention is also preferred, wherein the filter element is an air filter, preferably a cabin air filter, particularly preferably a cabin air filter for vehicles.
[0024] The method according to the invention is designed so that filter elements according to the invention can be produced in a substantially continuous process and / or in large quantities, while at the same time avoiding characteristic manufacturing defects. Accordingly, it is also preferred to operate the method according to the invention in this way. Preference is therefore given to a method according to the invention in which the method is a continuous or semi-continuous process, preferably a continuous process. With a view to the quantities that can be produced, it is advantageous to automate the process as much as possible. Against this background, preference is given to a method according to the invention in which the method is operated at a production rate of 2 or more, preferably 50 or more, particularly preferably 200 or more, filter elements per hour.
[0025] Continuous or semi-continuous process control can be particularly well implemented when the media used are provided via material rolls, from which the media can be continuously provided, apart from the occasional replacement of empty material rolls, and can be guided, for example, at a continuous feed rate through the devices used, for example, on a conveyor belt. Accordingly, a method according to the invention is preferred, wherein the first medium and / or the second medium, preferably both media in each case, are provided on a material roll.Additionally or alternatively, a method according to the invention is preferred, wherein the first medium is guided on a support, wherein the support is preferably a conveying device which particularly preferably conveys the first medium continuously through the device used, wherein the second medium is preferably arranged on the guided first medium during the merging.
[0026] In a first step, at least two flat, web-like media are provided. In accordance with expert understanding, flat elements have significantly larger dimensions in two spatial directions than in the third. Web-like flat elements have a significantly larger extension in one of the spatial directions than in the other. Examples of flat, web-like elements include, in particular, fabric webs or metal sheets, which can typically be stored on rollers.
[0027] The above definition of method step a) means that the first medium and the second medium must each have a carrier layer and that there is also at least one filter layer arrangement which comprises the further layers of the desired composite, whereby this can, however, be part of the first medium or part of the second medium, whereby it is also conceivable for both media to comprise a filter layer arrangement, i.e. to comprise further layers in addition to the carrier layer. However, in particular when carrying out the method with step b2), which, as described below, comprises cutting up the web-shaped second medium, the inventors believe it is advantageous if the filter layer arrangement is provided largely or even completely in the first medium, since this simplifies the processing of the second medium and minimizes the risk of damage to the filter layer arrangement which could occur during cutting up.Consequently, a method according to the invention is preferred, wherein the first medium comprises the first filter layer arrangement, and / or wherein the second medium consists of the second carrier layer.
[0028] The two carrier layers each comprise a nonwoven fabric and are therefore gas-permeable. As a result, the carrier layers in the manufactured filter element also serve synergistically as filter layers and contribute to the separation performance. In the manufactured filter elements, the two carrier layers also function, in particular, as conductive layers or electrodes, which determine the polarization of the filter layer arrangement(s) as a result of an applied electrical voltage.
[0029] For this purpose, the nonwovens used are coated with an electrically conductive material, at least in sections, and depending on the process and medium, preferably predominantly or even essentially over the entire surface. This increases the electrical conductivity of a mostly non-conductive nonwoven, thus enabling its functional use as an electrode. In addition to flat coatings, the required functionality can also be achieved through a patterned coating, as described further below.
[0030] In principle, the carrier layers can also comprise other components in addition to the nonwoven fabric, for example, reinforcing elements. However, with a view to cost-efficient production and the desired weight reduction, it is preferred for the carrier layers to consist essentially of the respective nonwoven fabric. Therefore, a method according to the invention is preferred, wherein the first carrier layer consists of the first nonwoven fabric coated at least in sections with an electrically conductive material, and / or wherein the second carrier layer consists of the second nonwoven fabric coated at least in sections with an electrically conductive material.
[0031] The term "coated" is to be interpreted broadly within the scope of expert understanding and encompasses all forms of coating the nonwoven fabric with the conductive material, even if this coating may include inclusions of electrically conductive material that are mechanically immobilized in the open-pore structure of the nonwoven fabric. The skilled person understands that, functionally, the increased electrical conductivity achieved by the coating, which is achieved through treatment with the conductive material, is important, and thus it is not necessary to characterize the exact nature of the interaction between the nonwoven fabric acting as a substrate and the electrically conductive material.However, a method according to the invention is generally preferred, wherein the first nonwoven fabric and / or the second nonwoven fabric, preferably the first nonwoven fabric and the second nonwoven fabric, are coated with the electrically conductive material in a method which is selected from the group consisting of impregnation, dip coating, spray coating or pressure coating.
[0032] In practice, the person skilled in the art readily distinguishes between an electrically conductive material and an electrically insulating material based on his or her expert and clear technical understanding of these terms. In this respect, a material is considered to be electrically conductive within the scope of the present invention in particular if its specific electrical resistance at 20 °C is 1000 Ω mm 2 / m or less, preferably at 100 Q mm 2 / m or less, particularly preferably 10 Q mm 2 / m or less. Conversely, a material is considered to be an electrically insulating material within the scope of the present invention if its specific electrical resistance at 20 °C is 10 8 Q mm 2 / m or more, preferably at 10 10 Q mm 2 / m or more, particularly preferably at 10 12 Q mm 2 / m or more. Accordingly, metals and alloys, but also carbon blacks and plastics made conductive by additives, such as in particular conductive carbon black, are electrically conductive materials, whereas typical plastics such as PET or PE are also electrically insulating materials, as are glasses and ceramics. In the opinion of the inventors, a method according to the invention is preferred, wherein the electrically conductive material of the first nonwoven fabric and / or the second nonwoven fabric, preferably both nonwoven fabrics, is selected from the group consisting of metals, conductive plastics and carbon, preferably carbon, in particular carbon black, wherein the electrically conductive material is particularly preferably identical for all nonwoven fabrics.
[0033] In practice, the extent of the coating of the second carrier layer depends primarily on the design of process step b). However, for the first carrier layer, it is particularly preferred, in view of ease of production, if it is comprehensively coated. Therefore, a method according to the invention is preferred, wherein the first nonwoven fabric of the first carrier layer is coated with the electrically conductive material over 80% or more of its surface, preferably over 90% or more, particularly preferably over 95% or more, very particularly preferably over 98% or more, particularly preferably substantially over its entire surface.In other words, a method according to the invention is preferred, wherein the first carrier layer, as a result of the coating of the first nonwoven fabric, is electrically conductive over at least 80% or more of the area, preferably over 90% or more, particularly preferably over 95% or more, very particularly preferably over 98% or more, and particularly preferably substantially over the entire area. A particularly relevant alternative embodiment of the first nonwoven fabric of the first carrier layer, which does not employ a planar coating, is considered to be the coating with a coating pattern, as further disclosed below.
[0034] The first and / or the second filter layer arrangement provide the layer by which the two carrier layers in the filter element are separated. With regard to the achievable filter performance and the low weight, it is considered particularly advantageous if the filter layer arrangement comprises or consists of an electrically insulating nonwoven fabric. A method according to the invention is preferred, wherein the first filter layer arrangement and / or the second filter layer arrangement, preferably the first filter layer arrangement, comprises a first filter layer, wherein the first filter layer comprises an electrically insulating third nonwoven fabric. A structure in which the produced filter element comprises such a first filter layer between the carrier layers is preferred for all embodiments.
[0035] The inventors have found that particularly high-performance filter elements can be obtained if the filter layer arrangement(s) includes at least one layer consisting predominantly of activated carbon, which enables excellent performance in the filtration of gas phases. With regard to mechanical strength and, in particular, mass-related separation efficiency, it was identified as advantageous if this activated carbon layer contains no fibrous components or other fillers that do not contribute to the adsorption properties of the activated carbon layer.By means of the method according to the invention and in filter elements according to the invention, it is advantageously not necessary, unlike in some filter elements of the prior art, for the activated carbon layer to contribute to the conductivity of the outer layers, which, in the opinion of the inventors, often only functions inadequately anyway. This advantageously allows the adsorption properties of the activated carbon layer to be in the foreground. Against this background, a method according to the invention is particularly preferred, wherein the first filter layer arrangement and / or the second filter layer arrangement, preferably the first filter layer arrangement, comprises a second filter layer, wherein the second filter layer comprises activated carbon, preferably particulate activated carbon, in a mass fraction of 70% or more, preferably 80% or more, particularly preferably 90% or more, especially preferably 95% or more, based on the mass of the second filter layer.Additionally or alternatively, a method according to the invention is preferred, wherein the second filter layer comprises a mass fraction of less than 1%, preferably less than 0.1%, particularly preferably less than 0.01% of fibrous materials. With regard to the selection of the activated carbon, a method according to the invention is preferred, wherein the activated carbon has a specific surface area of 500 m². 2 / g or more, preferably 1000 m 2 / g or more, particularly preferably 2000 m 2 / g or more. A structure in which the manufactured filter element comprises such a second filter layer between the carrier layers is preferred for all embodiments, with the combination with a first and a second filter layer being considered particularly favorable.
[0036] It can be considered an advantage of the method according to the invention and of the filter elements according to the invention that they are very flexible with regard to the presence of further layers in the filter layer arrangements and their arrangement in the composite. With the method according to the invention, additional layers and protective layers that support the filtration effect and / or capture certain health-relevant substances can advantageously also be provided in the filter element. In this respect, a method according to the invention is preferred, wherein the first filter layer arrangement and / or the second filter layer arrangement, preferably the first filter layer arrangement, comprises a first additional layer, wherein the first additional layer comprises an electrically insulating fourth nonwoven fabric, wherein the first additional layer is preferably arranged between the first filter layer and the second filter layer.In this respect, a method according to the invention is also preferred, wherein the first filter layer arrangement and / or the second filter layer arrangement, preferably the first filter layer arrangement, comprises a second additional layer, wherein the second additional layer comprises an electrically insulating fifth nonwoven fabric, wherein the second additional layer is preferably arranged between the second filter layer and a carrier layer, particularly preferably the first carrier layer. Additionally or alternatively, a method according to the invention is preferred, wherein the first filter layer arrangement and / or the second filter layer arrangement, preferably the first filter layer arrangement, comprises at least one first protective layer, wherein the first protective layer comprises one or more active ingredients selected from the group consisting of anti-allergenic active ingredients and biocidal active ingredients.
[0037] In process step b), the first medium and the second medium are connected to each other. This advantageously involves contacting the two media, which can be achieved, for example, by a suitable guide arrangement for one or both of the media. One of the two alternative process configurations described below should be considered. The joining and thus the creation of the web-like layer composite can, in principle, be carried out using conventional methods and, in the simplest case, can even be achieved by mechanical interlocking between the nonwovens of the contacted media.However, due to the simple handling and the advantageous adjustable bond strength, a method according to the invention is preferred, wherein the combining of the first medium with the second medium comprises connecting the first medium with the second medium by a material-to-material connection, preferably by means of an adhesive, for example in the edge regions of the web-shaped layer composite.
[0038] According to the invention, the joining takes place such that at least one of the filter layer arrangements is arranged at least in sections between the two carrier layers, so that it is also conceivable for only the first filter layer arrangement to be arranged between the carrier layers, whereas a second filter layer arrangement made of the second medium lies on the outside of the composite. However, a method according to the invention is preferred, wherein the joining takes place such that the first filter layer arrangement and the second filter layer arrangement are arranged at least in sections, preferably in the case of step b1) over the entire length of the web-shaped layer composite, between the first carrier layer and the second carrier layer, so that the first filter layer arrangement and the second filter layer arrangement are in contact with one another.In this case, the first filter layer arrangement and the second filter layer arrangement together form a so-called overall layer arrangement, which comprises the entirety of the layers arranged between the carrier layers and which is further described below with reference to the filter elements according to the invention.
[0039] The extent to which the filter layer arrangement(s) are arranged between the carrier layers depends in particular on the process control described below, wherein in particular in the variant with step b2) regions are formed between the partial regions of the second medium in which the filter layer arrangement(s) are arranged above the first carrier layer, but are not covered by the second carrier layer. In process step c), the filter elements are then produced, namely by singling out partial sections from the web-shaped layer composite, so that the filter element is obtained which comprises the two carrier layers and at least one of the filter layer arrangements between them, wherein this singling out takes place with a specific requirement which is described below.According to the inventors' findings, a method according to the invention is preferred, wherein the separation of the partial section of the web-shaped layer composite is carried out using a method selected from the group consisting of cutting, punching, and welding methods, preferably shear cutting, laser cutting, and ultrasonic welding. In other words, a method according to the invention is preferred, wherein the separation of the partial section of the web-shaped layer composite is carried out using a separation device, wherein the separation device is selected from the group consisting of flying knives, punching tools, laser beam cutters, and ultrasonic welding devices.
[0040] If a pleated filter is to be produced, the folding step can take place before, during, or after process step c). Thus, a method according to the invention is preferred, wherein the filter element is produced as a pleated filter element, wherein the web-shaped layer composite is folded at least in sections, preferably over the entire length of the section to be separated, before the sections are separated, or wherein the separated section of the web-shaped layer composite is folded at least in sections, preferably over the entire length of the separated section, after the separation, wherein the folding is particularly preferably carried out using a folding device.
[0041] In addition, additional electrodes can be applied before, during or after the separation, via which a voltage can be applied to the carrier layers. A method according to the invention is preferred, wherein one or more electrodes are arranged on the first carrier layer and / or on the second carrier layer, preferably on both carrier layers, before the separation in method step c), preferably before folding the web-shaped layer composite. Building on the method as described above, the design of method step b) is of particular importance for the method according to the invention. During the development of the invention, two basic alternative solutions for the design of method step b) have emerged, which the person skilled in the art can use to solve the problem.However, in the inventors' opinion, these alternative solutions each have additional advantages which, in practice, together with the question of the equipment available to the person skilled in the art, will determine the choice of process design.
[0042] In a first embodiment, process step b) may comprise step b1). A specifically designed second medium is used, namely a second medium whose carrier layers are coated with the electrically conductive material only in sections, the so-called coating regions. These coating regions are spaced apart from one another along the web direction, i.e., along the longitudinal direction of the flat, web-shaped second medium, so that there are intermediate regions arranged between the coating regions that are not electrically conductive.
[0043] The shape of the coating areas is expediently matched to the shape of the subsequent filter elements, so that, for example, even oblique contours and edges in the filter element can be anticipated via the coating areas. Therefore, a method according to the invention is preferred, wherein the shape of the coating areas in the second carrier layer essentially corresponds to the shape of the filter element to be produced. The selective coating of the second carrier layer in the coating areas can be achieved by spatially resolved coating, preferably by local printing, of the second nonwoven fabric. Particularly during printing, even complex shapes can be reproduced very efficiently.
[0044] In the inventors' opinion, it is expedient to provide a pronounced coating in each of the coating regions, thereby ensuring excellent conductivity, as also disclosed above for the first carrier layer as a whole. Therefore, a method according to the invention is preferred, wherein in step b1), the second nonwoven fabric of the second carrier layer is coated with the electrically conductive material in the coating regions over 80% or more of the area of the coating region, preferably over 90% or more, particularly preferably over 95% or more, very particularly preferably over 98% or more, and particularly preferably substantially over the entire area.In other words, a method according to the invention is preferred, wherein in step b1), as a result of the coating of the second nonwoven fabric, the second carrier layer is electrically conductive over at least 80% or more of the surface of the coating region, preferably over 90% or more, particularly preferably over 95% or more, very particularly preferably over 98% or more, particularly preferably substantially over the entire surface. In this respect, the coating regions can in particular also be coated with a coating pattern, wherein the above-defined areas are covered by the coating pattern, but the actual surface coverage with the electrically conductive material is lower, in particular 60% or less, preferably 40% or less, particularly preferably 30% or less.
[0045] Useful distances between the coating regions can be specified both absolutely and relative to the dimensions of the coating regions. A method according to the invention is preferred, wherein, in step b1), the coating regions in the second carrier layer along the web direction of the layer composite each have a distance in the range of 1 to 50 mm, preferably in the range of 3 to 20 mm, from adjacent coating regions, and / or wherein, in step b1), the coating regions in the second carrier layer along the web direction of the layer composite each have a distance in the range of 0.01*L to 0.1*L, preferably in the range of 0.02*L to 0.05*L, from adjacent coating regions, where L is the average length of the adjacent coating regions along the web direction of the layer composite.
[0046] In a second embodiment, method step b) may include step b2). Here, so-called partial regions are separated from a web-shaped second medium having a second carrier layer, for example, coated over its entire surface with the electrically conductive material, and arranged at a distance from one another on the web-shaped first medium, so that in this construction, too, a layered composite is obtained which has no electrically conductive connection between sections of the second medium spatially separated along the web direction.
[0047] In principle, the cutting can be carried out without waste or with waste, with the removal of a waste area between the sub-sections. In the former case, the spaced arrangement of the sub-sections can be conveniently achieved by different feed speeds of the web-like media, whereas the latter process creates a distance between the sub-sections by removing the waste area, even at the same feed speed.In this respect, on the one hand, a method according to the invention is preferred, wherein in step b2) the division of the partial regions of the second medium is carried out in such a way that, when dividing between the partial regions, substantially no waste region of the second medium is removed, wherein the division is preferably carried out by a non-cutting separation process, in particular a cutting process, wherein the spacing of the partial regions on the web-shaped first medium is preferably achieved at least partially, particularly preferably substantially completely, by the second medium being guided at a reduced speed and / or at a discontinuous timing, preferably at a reduced speed, relative to the first medium.On the other hand, a method according to the invention is preferred, wherein in step b2) the sub-regions of the second medium are divided such that a waste region of the second medium is removed during the division between the sub-regions, wherein the spacing of the sub-regions on the web-shaped first medium is created at least partially, preferably essentially completely, by the waste regions, wherein the second medium is preferably guided at essentially the same speed relative to the first medium. In the embodiment of step b2), a selective coating of the second carrier layer can advantageously be dispensed with. Even if, at least theoretically, a second carrier layer with coating regions could be used, as is necessary for step b1), with a view to simple process control and reduced manufacturing and / orIn order to reduce storage costs, it is advantageous to use fully coated second carrier layers when using step b2), which, in particularly preferred cases, can in particular also consist of the same materials as the first carrier layers. Accordingly, a method according to the invention is preferred, wherein in step b2), the second nonwoven fabric of the second carrier layer is coated with the electrically conductive material over 80% or more of its area, preferably over 90% or more, particularly preferably over 95% or more, very particularly preferably over 98% or more, particularly preferably essentially over its entire area.In other words, a method according to the invention is preferred in this respect, wherein the second carrier layer, as a result of the coating of the second nonwoven fabric, is electrically conductive over at least 80% or more of the area, preferably over 90% or more, particularly preferably over 95% or more, very particularly preferably over 98% or more, particularly preferably substantially over the entire area.
[0048] Additionally or alternatively, a method according to the invention is preferred, wherein the first nonwoven fabric and / or the second nonwoven fabric, preferably the first nonwoven fabric and the second nonwoven fabric, is coated with the conductive material in such a way that the first carrier layer and / or the second carrier layer has a pattern made of the conductive material, for example a grid pattern, wherein this pattern is designed in particular such that the first carrier layer and / or the second carrier layer have a continuous conductivity sufficient for the application.
[0049] In this respect, a method according to the invention is particularly preferred, wherein the pattern of the conductive material extends over 80% or more of the area, preferably over 90% or more, particularly preferably over 95% or more, very particularly preferably over 98% or more, of the area of the first nonwoven fabric and / or second nonwoven fabric. It is advantageous, by choosing the pattern, to keep the area coverage of the first carrier layer and / or the second carrier layer with the conductive material comparatively low, so that when using a coating pattern, a method according to the invention is preferred, wherein the first nonwoven fabric and / or the second nonwoven fabric is coated with the electrically conductive material over 60% or less of the area, preferably over 40% or less, particularly preferably over 30% or less.The above statements regarding the coating pattern apply accordingly to the design of the coating areas in step b1) if a coating pattern is used in these areas instead of a flat coating.
[0050] The separation of the subsections in method step c) is carried out with the proviso that the separation line, i.e. the cutting edge produced, for example, by scissor cutting, runs between two spaced-apart sections of the web-shaped layer composite in which the second carrier layer is conductive and thus in an intermediate region in which there is no second carrier layer or in which at least no coating ensures the electrical conductivity of the second carrier layer. Accordingly, the separation cut is set during separation in such a way that the separation line for step b1) runs between two adjacent coating regions or for step b2) between two adjacent subsections. In other words, the separation is carried out in such a way that the separation tool does not touch the coating regions in step b1) or the subsections in step b2).
[0051] This advantageously ensures that the separation and the associated mechanical and / or thermal stress occur exclusively in an area where the second carrier layer acting as an electrode is not present or at least is not coated with a conductive material. This reliably prevents unwanted contact and / or fusion of the electrically conductive layers, even at high production speeds. Accordingly, for the inherently preferred construction of the filter elements according to the invention, which rely on the advantageous use of conductive layers made of coated nonwoven fabric and are therefore particularly light and thin while providing excellent filter performance, continuous manufacturing processes with separation from a web-like layer composite can be realized, thus providing a particularly time- and cost-efficient manufacturing process.The specific design of the web-shaped layer composite and the positioning of the cutting areas ensure such a favorable spatial separation of the carrier layers separated by the filter layer arrangement(s) that even under the loads occurring during use in the vehicle, unwanted contact and the associated short circuit can be reliably excluded, even and especially in the case of folded, i.e. pleated filters.
[0052] In order to support this effect in a synergistic manner, the inventors believe it is extremely preferable if the nonwovens used themselves consist of an electrically insulating material and thus only become sufficiently electrically conductive through the coating. In particular, when carrying out the process with step b1), in which contact can occur between the coated first carrier layer and the uncoated parts of the second carrier layer in the intersection area in the edge region of the filter elements, a short circuit can be effectively avoided even at high voltages. For all embodiments, a process according to the invention is preferred, wherein the first nonwoven fabric and / or the second nonwoven fabric and / or the third nonwoven fabric, preferably all nonwoven fabrics, are made of plastic, in particular electrically insulating plastic, wherein the plastic is preferably a polyester, particularly preferably polyethylene terephthalate (PET).
[0053] In order to further enhance the short-circuit protection achieved in view of the optimized nature of the filter elements according to the invention at the separating edge, the inventors propose that the second carrier layer, regardless of the process control selected in process step b), ideally be designed with a smaller width than the filter layer arrangement(s) or even than the entire first medium, so that the first carrier layer can be arranged centrally on the first medium or the entire layer arrangement. Accordingly, a method according to the invention is preferred, wherein the width of the first medium and / or the second filter layer arrangement, preferably of the first medium and the second filter layer arrangement, transversely to the web direction is greater than the width of the second carrier layer, preferably by 1% or more, particularly preferably by 2% or more, particularly preferably by 5% or more.At the same time, however, with a view to manufacturing efficiency and the fitting of the filter elements into filters, it is preferable not to make the overhang too pronounced. Accordingly, a method according to the invention is preferred, wherein the width of the first medium and / or the second filter layer arrangement, preferably of the first medium and the second filter layer arrangement, transversely to the web direction is greater than the width of the second carrier layer, preferably by 30% or less, particularly preferably by 15% or less, particularly preferably by 5% or less. In this case, the above-defined limits are particularly preferably combined into ranges.Accordingly, a method according to the invention is also preferred, wherein the second medium is arranged on the first medium during the merging in method step b) in such a way that the first medium, preferably at least the first filter layer arrangement of the first medium, projects beyond the second medium on both sides along the web direction.
[0054] Finally, the inventors have succeeded in identifying particularly favorable material parameters for the components identified above, which allow for the production of particularly efficient filter elements. In particularly preferred embodiments, the following illustrations combine equally preferred features.
[0055] With regard to the desired electrical conductivity of the components, a method according to the invention is preferred, wherein the first carrier layer, at least in sections, preferably over its entire surface, has an average electrical conductivity in the range of 10' 2 up to 10' 11 1 / (Q m), preferably in the range of 10' 4 up to 10' 7 1 / (Q m), and / or wherein the second carrier layer in step b1) has an average electrical conductivity in the range of 10' 2 up to 10' 11 1 / (Q m), preferably in the range of 10' 4 up to 10' 7 1 / (Q m), and / or wherein the second carrier layer in step b2) at least partially, preferably over the entire surface, has an average electrical conductivity in the range of 10' 2 up to 10' 11 1 / (Q m), preferably in the range of 10 -4 up to 10 -71 / (Q m). To ensure a sufficient volume flow rate and an advantageously low pressure drop, a method according to the invention is preferred, wherein the first nonwoven fabric has an air flow rate in the range of 300 to 30,000 L / (m 2 s), preferably in the range of 2000 to 20000 L / (m 2 s), and / or wherein the second nonwoven fabric has an air permeability in the range of 300 to 30,000 L / (m 2 s), preferably in the range of 2000 to 20000 L / (m 2 s), and / or wherein the third nonwoven fabric has an air permeability in the range of 400 to 8000 L / (m 2 s), preferably in the range of 500 to 6000 L / (m 2 s), and / or wherein the fourth nonwoven fabric has an air permeability in the range of 300 to 30,000 L / (m 2 s), preferably in the range of 2000 to 20000 L / (m 2 s).
[0056] Finally, the inventors were also able to identify suitable values for the density of the nonwovens. A preferred method according to the invention is one in which the first nonwoven has a basis weight in the range of 5 to 500 g / m 2 , preferably in the range of 10 to 150 g / m 2 , and / or wherein the second nonwoven fabric has a basis weight in the range of 5 to 500 g / m 2 , preferably in the range of 10 to 150 g / m 2 , and / or wherein the third nonwoven fabric has a basis weight in the range of 15 to 300 g / m 2 , preferably in the range of 50 to 100 g / m 2 , has.
[0057] The person skilled in the art understands that the invention also relates to a filter element which is produced or can be produced using the method according to the invention, comprising: x) a first carrier layer made of a first nonwoven fabric coated at least in sections with an electrically conductive material, y) a second carrier layer made of a second nonwoven fabric coated at least in sections with an electrically conductive material, and z) an overall layer arrangement arranged between the first carrier layer and the second carrier layer.The person skilled in the art will further understand that the invention also relates to a particularly preferred specific filter element, preferably produced or producible using the method according to the invention, comprising: x) a first carrier layer made of a first nonwoven fabric coated at least in sections with an electrically conductive material, y) a second carrier layer made of a second nonwoven fabric coated at least in sections with an electrically conductive material, z) an overall layer arrangement arranged between the first carrier layer and the second carrier layer, wherein the overall filter layer arrangement comprises a first filter layer, wherein the first filter layer comprises an electrically insulating third nonwoven fabric, and wherein the overall filter layer arrangement comprises a second filter layer, wherein the second filter layer comprises activated carbon in a mass fraction of 70% or more, based on the mass of the second filter layer.
[0058] Corresponding preferred filter elements according to the invention are characterized by very good filter performance combined with low weight and very good mechanical stability and can also be produced particularly time- and cost-efficiently.
[0059] A filter element according to the invention is preferred, wherein the second carrier layer or a coating region of the second carrier layer, in which the second nonwoven fabric is coated with an electrically conductive material, has a smaller area than the first filter layer, and / or wherein at least one edge of the second carrier layer or an edge of the coating region of the second carrier layer is spaced from the nearest edge of the filter layer in the plan view of the filter element.
[0060] Based on this, the invention also relates to a filter comprising an air inlet and an air outlet as well as a filter element according to the invention, wherein the filter element is arranged between the air inlet and the air outlet, wherein the filter preferably comprises an integrated ionization device for ionizing particles.
[0061] Also disclosed is a device for carrying out the method according to the invention, comprising: o) an electronic control and regulation unit for controlling the method, p) a first roller for providing the first medium and a second roller for providing the second medium, q) a guide arrangement for contacting the first medium and the second medium, and r) a separating device for separating a partial section of the web-shaped layer composite to obtain filter elements, and optionally: s) a folding device for folding the web-shaped layer composite.
[0062] The invention and preferred embodiments of the invention are explained and described in more detail below with reference to the accompanying figures. The figures show:
[0063] Fig. 1 is a schematic representation of a method according to the invention in a first preferred embodiment;
[0064] Fig. 2 is a schematic representation of a layered composite that can be produced using the method shown in Fig. 1 in a first preferred embodiment in plan view and in cross-sectional view;
[0065] Fig. 3 is a schematic representation of a layered composite that can be produced using the method shown in Fig. 1 in a second preferred embodiment, in plan view; Fig. 4 is a schematic representation of the method according to the invention in a second preferred embodiment;
[0066] Fig. 5 is a schematic representation of the method according to the invention in a third preferred embodiment;
[0067] Fig. 6 is a schematic representation of the method according to the invention in a fourth preferred embodiment; and
[0068] Fig. 7 is a schematic representation of a selection of preferred arrangements of layers to be used in filter elements of the method according to the invention or in filter elements according to the invention.
[0069] Fig. 1 shows a schematic representation of a method according to the invention for producing filter elements 12 in a preferred embodiment, including step b1). The filter elements 12 produced by the method shown are interior air filters for vehicles.
[0070] In the example shown, a first web-shaped medium 14 and a second web-shaped medium 18 are each provided on a roll of material. The process is operated continuously and controlled and regulated by an electronic control and regulation unit (not shown).
[0071] In the example shown, the second web-shaped medium 18 consists of a second carrier layer 20 designed as a nonwoven fabric, which has an air permeability of approximately 3000 L / (m 2 *s).
[0072] The first web-shaped medium 14 contains a first carrier layer 16, which is also made of an electrically insulating first nonwoven fabric, which at 200 Pa also has an air permeability of approximately 3000 L / (m 2*s). In addition, the first web-shaped medium 14 contains a first filter layer arrangement, which comprises the further layers of the desired composite and accordingly has different filter layers and / or additional layers, which, given the absence of a second filter layer arrangement in the second medium 18, will form the overall filter layer arrangement 34 in the filter element 12. This overall filter layer arrangement 34 as well as the basic structure of preferred filter elements 12 comprising different layers are also shown in particular in Fig. 7 ad.
[0073] In the example shown, both the first carrier layer 16 and the second carrier layer 20 are coated with an electrically conductive material, which in this case is carbon black. The first carrier layer 16 is coated essentially over its entire surface, whereas the second carrier layer 20, in order to implement the method according to Fig. 1, only has a coating in sections in the so-called coating regions 24, which are spaced apart from one another along the web direction. In the coating regions 24, the second carrier layer 20 is coated over its entire surface with carbon black, for example by spatially resolved coating, in particular printing. The spacing of the coating regions 24 from one another along the web direction of the layer composite 22 results in intermediate regions in which the second carrier layer 20 is not electrically conductive.
[0074] In the example shown, the first medium 14 and the second medium 18 are bonded together with an adhesive after being unrolled from the respective material roll. In the embodiment shown, the first medium 14 and the second medium 18 are joined together by the two material rolls running essentially synchronously, so that the arrangement of the first medium 14 over the second medium 18 results in a layered composite 22, as shown in Figs. 2 and 3.
[0075] By separating sections along the uncoated intermediate regions, the layered composite 22 can be cut to length to obtain the filter element 12. This advantageously ensures that the separation and the associated mechanical and / or thermal stress occur exclusively in an area in which the second carrier layer 20, which functions as an electrode, is not coated with a conductive coating.
[0076] Fig. 2 shows a layer composite 22 produced by the method shown in Fig. 1 in a plan view, as well as a cross-sectional view of this layer composite 22 from the viewing direction of the arrow shown, which visualizes its structure transverse to the web direction.
[0077] In the example shown, the overall filter layer arrangement 34 consists of a first filter layer 30 and a second filter layer 32 and not only spatially separates the first carrier layer 16 and the second carrier layer 20, but also acts as electrical insulation between the carrier layers, see also Fig. 7a-d. In order to further reduce the risk of a short circuit between the conductive regions of the first carrier layer 16 and the second carrier layer 20, the second carrier layer 20 is designed with a reduced width compared to the layers of the first medium 14, i.e. compared to the first carrier layer 14, the first filter layer 30 and the second filter layer 32.
[0078] As described above, filter elements 12 can be obtained from the web-shaped layer composite 22 by dividing the layer composite 22 along the dividing line 28 into individual filter elements 12, wherein the dividing lines 28 are arranged in the intermediate regions, i.e., between the coating regions 24. As shown in Fig. 3, different geometric shapes of the filter element 12 can also be produced using the method by matching the shape of the coating regions 24 to the shape of the subsequent filter elements 12. In this respect, for example, oblique contours and edges in the filter element 12 can already be anticipated via the coating regions 24.
[0079] 4 to 6 each show schematic representations of the method according to the invention in further preferred embodiments with step b2). The methods shown differ in particular from the method of Fig. 1 in that the second medium 18 or its second carrier layer 20 and the second nonwoven fabric encompassed by this second carrier layer 20 does not comprise any coating regions 24 in the method shown, and is separated in the method into partial regions 26 which are arranged at a distance from one another on the web-shaped first medium 14 such that, in this structure too, a layer composite 22 is obtained which has no electrically conductive connection between sections of the second medium 18 which are spatially separated along the web direction. In this respect, it is advantageously possible in this method to form the second medium 18 from a fully coated second carrier layer 20.
[0080] The division of the second medium 18 into sub-regions 26 can, as shown in Figs. 5 and 6, in principle be carried out without waste using a non-cutting separation process. The spaced arrangement of the sub-regions 26 can be achieved by different feed speeds of the web-shaped media, for example, by a reduced speed and / or a discontinuous timing of the second medium 18 relative to the first medium 14.
[0081] The division of the partial areas 26 can also be carried out, as shown in Fig. 7, by removing a waste area between the partial areas 26. In this case, the process control can create a distance between the partial areas 26 through the removed waste area at the same feed rate of the material rolls of the first medium 14 and the second medium 18. In the example shown in Fig. 7, this waste area is realized by a circularly rotating carriage arrangement and a cutting tool, wherein the carriage locally lifts the second medium 18 at predetermined intervals and guides it against the cutting tool in order to cut out the waste area.
[0082] In principle, the second medium 18 can be divided into subregions 26, as shown in Figs. 4 and 6, before the first medium 14 and the second medium 18 are combined. However, as shown in Fig. 5, it is also possible to separate the subregions 26 only after the combination has taken place.
[0083] As already described above for the method shown in Fig. 1, the final production of the filter elements 12 takes place by separating sections from the web-shaped layer composite 22 using a separating device. During separation, the separating cut is made in such a way that the separating line 28 between two adjacent partial regions 26 runs in such a way that the separation takes place in an area in which the second carrier layer 20 acting as an electrode is not present. If a pleated filter element 12 is to be produced, as indicated in Fig. 5 and as is explicitly preferred for each of the methods shown here, the folding step can take place before, during, or after the separation.
[0084] In Fig. 7, arrangements of filter elements 12 produced by the method according to the invention or of preferred filter elements 12 according to the invention are shown. The overall filter layer arrangement 34 comprises in all embodiments a) to d) at least the first filter layer 30 consisting of a third nonwoven fabric and the second filter layer 32 containing granular activated carbon, wherein the activated carbon has, for example, a specific surface area of 2000 m 2 / g or more and essentially contains no fibrous materials. The activated carbon layer in the example shown consists of approximately 200 g / m 2 Activated carbon, which contains about 15 g / m 2 Binder is added.
[0085] It is also preferred to provide a first additional layer 36 containing a third nonwoven fabric, which is arranged, for example, between the first filter layer 30 and the second filter layer 32, as shown in Fig. 7b), but which can alternatively also be placed at other locations, for example between the second carrier layer 20 and the first filter layer 30. Additionally or alternatively, a second additional layer 38 can be provided, which comprises a fourth nonwoven fabric and is arranged between the first carrier layer 16 and the second filter layer 32, as shown in Fig. 7c) or Fig. 7d). In each of the above-described embodiments of the filter element 12, it is also explicitly preferred if the overall filter layer arrangement 34 comprises at least one first protective layer (not shown) containing antiallergenic active ingredients and / or biocidal active ingredients. Reference numerals
[0086] 12 filter element
[0087] 14 first medium
[0088] 16 first carrier layer 18 second medium
[0089] 20 second carrier layer
[0090] 22 layer composite
[0091] 24 Coating area
[0092] 26 Sub-area 28 Dividing line
[0093] 30 first filter layer
[0094] 32 second filter layer
[0095] 34 Total filter layer arrangement
[0096] 36 first additional layer 38 second additional layer
Claims
Claims: A method for manufacturing a filter element (12), in particular for use in electrostatic precipitators, comprising the process steps of: a) manufacturing or providing a planar, web-shaped first medium (14) comprising a first support layer (16) comprising a first nonwoven fabric coated at least partially with an electrically conductive material, and manufacturing or providing a planar, web-shaped second medium (18) comprising a second support layer (20) comprising a second nonwoven fabric coated at least partially with an electrically conductive material, wherein the first medium (14) comprises a first filter layer arrangement connected to the first support layer (16), and / or wherein the second medium (18) comprises a second filter layer arrangement connected to the second support layer (20), b) combining the first medium (14) with the second medium (18) to obtain a web-shaped layer composite (22),wherein the merging is carried out such that the first filter layer arrangement and / or the second filter layer arrangement are arranged at least sectionally between the first support layer (16) and the second support layer (20), and c) separating a partial section of the web-shaped layer composite (22) to obtain the filter element (12), comprising a part of the first support layer (16) and the second support layer (20) as well as the first filter layer arrangement and / or the second filter layer arrangement, wherein the merging in process step b) comprises one of the following steps: b1) applying the web-shaped second medium (18) to the web-shaped first medium (14), wherein the second support layer (20) comprises a plurality of separate elements along the web direction of the, a) The process comprises the layered composite (22) and spaced-apart coating areas (24) in which the second nonwoven fabric is coated with the electrically conductive material, or b2) the web-shaped second medium (18) is divided to obtain a plurality of sub-areas (26), wherein the merging is carried out such that the sub-areas (26) are spaced apart from one another along the web direction of the layered composite (22), wherein the second nonwoven fabric of the second carrier layer (20) is coated at least sectionally with the electrically conductive material in the sub-areas (26), and wherein the separation of the sub-section from the web-shaped layered composite (22) in process step c) is carried out such that the separation line (28) runs between two adjacent coating areas (24) or two adjacent sub-areas (26). The process according to claim 1, wherein the process is a continuous or semi-continuous process, preferably a continuous process.A method according to claim 1 or 2, wherein the first filter layer arrangement and / or the second filter layer arrangement comprises a first filter layer (30), wherein the first filter layer (30) comprises an electrically insulating third nonwoven fabric. A method according to any one of claims 1 to 3, wherein the first filter layer arrangement and / or the second filter layer arrangement comprises a second filter layer (32), wherein the second filter layer (32) comprises activated carbon in a mass fraction of 70% or more, based on the mass of the second filter layer (32).
5. Method according to one of claims 1 to 4, wherein the filter element (12) is produced as a pleated filter element, wherein the web-shaped layered composite (22) is folded at least section by section, preferably over the entire length of the section to be separated, before the partial sections are separated, or wherein the separated partial section of the web-shaped layered composite (22) is folded at least section by section, preferably over the entire length of the separated partial section after separation.
6. Method according to any one of claims 1 to 5, wherein the separation of the partial section of the web-shaped layer composite (22) is carried out by a method selected from the group consisting of cutting, punching and welding methods, preferably shear cutting, laser cutting and ultrasonic welding.
7. Method according to any one of claims 1 to 6, wherein the width of the first medium (14) transverse to the web direction is greater than the width of the second medium (18), preferably by 1% or more.
8. Method according to any one of claims 1 to 7, wherein in step b1) the coating areas (24) are produced by spatially resolved coating, preferably by local printing, of the second nonwoven fabric.
9. Method according to any one of claims 1 to 8, wherein in step b1) the coating areas (24) in the second carrier layer (20) along the web direction of the layer composite (22) to adjacent coating areas (24) each have a distance in the range of 0.01*L up to 0.1*L, preferably in the range of 0.02*L to 0.05*L, wherein L is the mean length of the adjacent coating areas (24) along the web direction of the layer composite (22).
10. Method according to any one of claims 1 to 9, wherein in step b2) the second nonwoven fabric of the second carrier layer (20) is coated with the electrically conductive material over 80% or more of the area.
11. Method according to any one of claims 1 to 10, wherein in step b2) at There is essentially no division between the sub-areas The cut area of the second medium (18) is removed, wherein the cutting is preferably carried out by a chipless cutting process, in particular a cutting process, wherein the spacing of the partial areas (26) on the web-shaped first medium (14) is preferably achieved at least partially by guiding the second medium (18) at a reduced speed and / or with a discontinuous timing, preferably at a reduced speed, relative to the first medium (14).
12. Method according to any one of claims 1 to 10, wherein in step b2) the dividing of the second medium (18) is carried out such that, during dividing, a cutting area of the second medium is removed between the partial areas (26), wherein the spacing of the partial areas (26) on the web-shaped first medium (14) is at least partially generated by the cutting areas, wherein the second medium (18) is preferably guided at substantially the same speed relative to the first medium (14). Filter element (12), preferably manufactured or manufacturable by the method according to one of claims 1 to 12, comprising: x) a first support layer (16) made of a first nonwoven fabric coated at least partially with an electrically conductive material, y) a second support layer (20) made of a second nonwoven fabric coated at least partially with an electrically conductive material, z) a total filter layer arrangement (34) arranged between the first support layer (16) and the second support layer (20), wherein the total filter layer arrangement (34) comprises a first filter layer (30), wherein the first filter layer (30) comprises an electrically insulating third nonwoven fabric, and wherein the total filter layer arrangement (34) comprises a second filter layer (32), wherein the second filter layer (32) comprises activated carbon in a mass fraction of 70% or more, based on the mass of the second filter layer.Filter comprising an air inlet and an air outlet as well as a filter element (12) according to claim 13, wherein the filter element (12) is arranged between the air inlet and the air outlet, wherein the filter preferably comprises an integrated ionization device for ionizing particles.