DE102007018937A1 - Filter material, useful as filter e.g. cabin air filter, circulating air filter and/or vacuum cleaner filter, comprises a carrier layer and an adsorption filter layer, which is formed by hot-melt fibers charged with adsorber particle - Google Patents

Abstract

Filter material comprises a carrier layer and an adsorption filter layer, which is formed by hot-melt fibers charged with adsorber particle, where the hot-melt fibers contains charge carrier and/or charge stabilizer and exhibits a charge and/or is rechargeable. An independent claim is included for preparing a filter material comprising spinning the hot-melt fibers that is charged with adsorber particle and applying on a carrier layer, where the hot-melt fibers are electrically charged during the spinning.

Description

The The present invention relates to a filter material having a carrier layer and an absorption filter layer, and a method of manufacturing the same, wherein the adsorption filter layer of adsorber particles loaded melt adhesive threads is formed and wherein further the melt adhesive threads charge carriers and / or Charge stabilizers include and the melt adhesive threads have a charge and / or are rechargeable. A preferred application for such filter materials is the use as Cabin air filter, circulating air filter, clean room filter, exhaust air filter, domestic filter and / or vacuum cleaner filters.

From the prior art, a number of different filters and processes for their preparation are known. These filters known from the prior art can be subdivided into those in which activated carbon particles are arranged on the fibers of an adsorber layer ( DE 198 45 526 A1 ). The cleaning effect of these filters is mainly due to adsorption. Furthermore, filters are known in which the fibers of a filter layer is electrically charged ( DE 101 09 474 C1 ). The cleaning effect comes about in these filters mainly by filtration. While activated carbon-based filters are suitable for binding gaseous substances by adsorption, electrically charged filters are suitable, in particular for the filtration of fine dust.

To be able to bind fine dust with activated carbon-based filters by filtration, very fine-meshed fiber layers are required, which cause a high pressure drop at the filters. Therefore, the use of activated carbon-based filters for filtration of fine dust is not known, since between the adsorber particles sufficiently large pores are necessary to keep the flow resistance low. By means of such open structures, however, sufficient particle filter effects can not be achieved by filtration effects. In order to achieve a good adsorptive effect together with a sufficient filtration effect, separate layers of adsorbers and particulate matter filters are used in the prior art ( DE 102 49 998 B3 ).

task The present invention is therefore an improved and To provide simplified filter, the fine dust at a low Pressure drop binds and also adsorbs gaseous pollutants.

These Task is solved by a filter material comprising a carrier layer and an adsorption filter layer, wherein the adsorption filter layer of loaded with adsorbent particles Melt adhesive threads is formed and further wherein the melt adhesive threads Charge carriers and / or charge stabilizers comprise and the melt adhesive threads have a charge and / or rechargeable are.

Surprisingly can extremely fine dust from the filter element according to the invention adsorbed efficiently over a longer period of time because the charge stabilizes on the melt adhesive threads is without causing a major pressure drop comes on the filter.

By the charge in and / or on the melt adhesive threads is Particulate matter attracted and bound by the filter, creating a filtration effect arises. Preferably, particles of less than 3 microns, more preferably in a range of 100 nm to 2 μm, bound. The adsorber particles preferably adsorb gaseous and / or liquid substances.

Surprisingly combines a filter with adsorbent particles and melt adhesive threads with charge carriers and / or charge stabilizers the cleaning effect of adsorption and filtration elements, resulting in a simplified Filter can be provided, wherein at the same time the Pressure drop is lower than when adsorber and melt adhesive threads with charge carriers and / or charge stabilizers in separate Filter elements are provided.

Amazingly, is achieved by combining a filter with adsorbent particles and Melt adhesive threads with charge carriers and / or Charge stabilizers also achieved improved separation efficiency.

Under an adsorption filter according to the invention is a Layer understood, both by adsorption and by filtration gaseous, liquid and / or particulate Retains substances.

Under Hotmelt adhesive threads that are rechargeable is within the meaning of Understand the present invention that in and / or on the melt adhesive threads by the action of an electric field, an ionic and / or a partial charge can be generated.

Under Hotmelt adhesive threads which have charge is in the sense the present invention to understand that the melt adhesive threads have an ionic charge and / or a partial charge.

charge carrier For the purposes of the invention are preferably substances which are a charge carry and / or on the one charge, z. B. by charge separation, can be applied.

charge stabilizers For the purposes of the present invention, substances are preferably the charges already present in the adsorption filter layer can stabilize.

In one embodiment of the filter element according to the invention, the melt adhesive threads have a surface charge density of 10 ^-8 to 10 ^-6 C / cm ² . Preferably, the melt adhesive threads have a surface charge density of 10 ^-7 to 5 × 10 ^-7 C / cm ² .

at an embodiment of the invention Filter element, the adsorber filter layer has a thickness in one Range of 50 microns to 500 microns, preferably 100 microns up to 250 μm, on.

at an embodiment of the invention Filter material, the adsorbent particles are powdery and / or granular and preferably selected from the group consisting of zeolites, Silica gels, activated charcoal, alumina, calcium chloride and mixtures of which exists.

The Charge stabilizers and / or charge carriers in the sense of present invention have a decomposition temperature over the softening point of the melt adhesive threads lies.

at In one embodiment, the charge carriers and / or Charge stabilizers organic and / or inorganic salts and / or Substances which displaceable charges, z. B is a Π-electron system. It can be used polar substances that are align in the electric field. In the electric field align the polar substances in the melt adhesive threads and generate and / or stabilize thereby the charge in the melt adhesive threads.

at a preferred embodiment of the invention Filter material are the charge carriers and / or charge stabilizers from the group consisting of organic and inorganic salts, salt-like Compounds, ionic polymers, halogenated, especially fluorinated Hydrocarbons, organometallic complex compounds, in particular Metallocenes, half-sandwich complexes, dyes, in particular azo dyes, Compounds with a conjugated Π-electron system and mixtures thereof. Preferably, the organic and inorganic salts and / or salt-like compounds large anions with a molecular weight of preferably over 70 g / mol, more preferably over 300, most preferably over 1000 g / mol.

For example can be used as a charge carrier and / or charge stabilizer Sulfonic acid esters, such as, for example, toluenesulfonic acid esters, be used.

at an embodiment of the invention Filter element are called charge carriers and / or charge stabilizer Ammonium salts with carbon water residues, preferably with 8 to 20 carbon atoms, more preferably 10 to 16 carbon atoms, such as tetrakis (decyl) ammonium bromide and / or tetradecyltrimethylammonium bromide, used.

In one embodiment of the filter element according to the invention, fatty acid salts, for example alkali metal and / or alkaline earth fatty acid salts, which are preferably linear, are used as charge carriers and / or charge stabilizers. It is further preferred that the fatty acids are selected from fatty acids having a chain length of C ₁₀ to C ₂₀ , preferably C ₁₈ to C ₂₀ . As a very suitable charge carrier and / or charge stabilizer, sodium oleate and / or potassium stearate have been found.

at an embodiment of the invention Filter element are called charge carriers and / or charge stabilizer Azo dyes used. For example, as charge carriers and / or charge stabilizer methyl red, fuchsin red, methyl orange, Sudan red and / or real violet used.

at an embodiment of the invention Filter element are called charge carriers and / or charge stabilizer Salts, such as barium titanate, sodium citrate and / or mixtures thereof, used.

In a particularly preferred embodiment of the filter material according to the invention the melt adhesive threads as charge carriers and / or charge stabilizers sodium oleate and / or polyacrylic acid sodium salt. In a further particularly preferred embodiment of the filter material according to the invention, the melt adhesive threads as charge carriers and / or charge stabilizers comprise ferrocene and / or zirconocene.

at an embodiment of the invention Filter element is the hot melt adhesive from the group consisting of a polyolefin, polyester, polyamide and mixtures thereof, and the charge stabilizer comprises sodium oleate and / or barium titanate.

The Adsorberpartikel preferably adhere firmly to the melt adhesive threads.

at an embodiment of the invention Filter material adhere the Adsorberpartikel a small area at the melt adhesive threads. Under a small area For the purposes of the invention is preferably to be understood that at most 30%, preferably at most 10%, of the outer Surface of the adsorber particles on the melt adhesive threads adhere and / or covered with the hot melt adhesive. This will the adsorption of Adsorberpartikel not and / or only insignificantly impaired. Under outer surface within the meaning of the invention is preferably the surface to understand the externally directly accessible is.

Under Melt adhesive threads in the sense of the present invention are preferably threads from at room temperature, d. H. at 25 ° C, solid, to understand polymer adhesives, preferably less than 5% by weight, more preferably less than 1% by weight, on most preferably no water and / or solvent based on the total weight of the hot melt, contained in the hot Condition, preferably above 50 ° C, no adhesive effect and after cooling to room temperature their Unfold adhesive effect.

melt adhesive are usually at elevated temperatures, d. H. at over 50 ° C, to be bonded together Apply melted objects and harden after assembly, upon cooling to room temperature with solidification preferably without a chemical reaction.

The Adsorber particles are preferably uniform, in particular along and around the entire circumference of the melt adhesive threads, distributed on the melt adhesive threads. Preferably have Melt adhesive threads in the context of the invention in the unmelted Condition no stickiness among each other and bind the Adsorberpartikel. Preferably, the melt adhesive threads form a three-dimensional Network off. Preferably, the melt adhesive threads are suitable to bind adsorber particles in the molten state.

In one embodiment of the filter material according to the invention, the hot-melt adhesive is formed from a material based on polyester, polyolefin, polycarbonate, polyurethane and / or polyamide, wherein preferably the hot melt adhesive is polymer-uniform to the carrier layer. Particularly preferably, the hot melt adhesive consists of a material based on polyester and polyolefin. In one embodiment, the weight per unit area of adsorbent particles is 100 to 1500 g / m ² , preferably 400 to 1200 g / m ² .

By the firm adhesion of the adsorber particles to the melt adhesive threads the adsorption filter layer consists of a random, three-dimensional Net from which the adsorber particles do not dissolve. hereby at the same time a high air permeability at a high adsorption capacity and high spontaneity allows. Spontaneity is the initial one Adsorption capacity, d. H. the adsorption in the initial state to understand without loading. Due to the electrostatic charge the filter also effectively retains the particulate matter without the need for a close-meshed three-dimensional network, which lead to a reduced air permeability would.

at an embodiment of the invention Filter material is the carrier layer of a nonwoven Polyester, polyolefin, polycarbonate, polyurethane, polyamide base, made of reticulated PUR foam and / or mixtures thereof.

In one embodiment of the filter material according to the invention, for example when the filter is subject to a particularly strong mechanical load, a cover layer is arranged on the side of the adsorber layer facing away from the carrier layer. This cover layer may consist of a nonwoven, scrim, knitted or knitted fabric and is preferably made of a material which is polymer-uniform to the material of the support layer and / or the hot melt adhesive. Preferably, the cover layer absorbs particles having a mean particle size of greater than 3 microns, preferably from 3 microns to 500 microns. More preferably, the cover layer adsorbs particles having an average particle size of 3 microns to 20 microns, most The cover layer preferably adsorbs particles having an average particle size of 3 μm to 10 μm.

at an embodiment of the invention Filter material, the adsorbent particles have a mean diameter in a range of 50 μm to 5 mm, preferably in one Range of 50 microns to 500 microns.

The Hot melt adhesive threads comprise a hot melt adhesive, which is preferably has a melting point between 75 and 200 ° C, in particular between 100 and 150 ° C. Preferably, the melting point is of the hot melt adhesive at least 50 ° C below the melting point the material of the carrier layer.

at In one embodiment, the hot melt adhesive can be retrofitted to be postcrosslinked. This is especially advantageous if the filter material used in a high temperature environment shall be. Preferably, the melt adhesive threads after curing thermosetting properties.

at an embodiment of the invention Filter material, the melt adhesive threads have a diameter on, which is at least a factor of 10 smaller than the diameter the Adsorberpartikel. This will allow the Melt adhesive threads only with a small part of the outer Surface of the adsorbent particles in contact. This also allows a very low proportion of hot melt adhesive. In one embodiment, the proportion of melt adhesive threads is at 2 to 10 wt .-%, preferably 5 to 8 wt .-%, based on the Total weight of the adsorber layer.

at an embodiment of the invention Filter material, the melt adhesive threads have a thickness in a range of 5 to 50 μm, preferably 10 to 20 μm, on.

at an embodiment of the invention Filter material are the charge stabilizers and / or charge carriers in an amount of 0.1 to 10% by weight, preferably 3 to 5% by weight, based on the weight of the hot melt adhesive, distributed in the hot melt adhesive.

In one embodiment of the filter material according to the invention, the charge stabilizers and / or charge carriers are compatible with the hotmelt adhesive. Compatible within the meaning of the invention means that the hotmelt adhesive and the charge carrier and / or the charge stabilizer form a homogeneous mixture. Preferably, a polar hot melt adhesive and a polar charge carrier and / or polar charge stabilizer are used, or a nonpolar hot melt adhesive and a nonpolar charge carrier and / or nonpolar charge stabilizer are used. For example, ammonium salts with long, nonpolar alkyl substituents, such as C ₁₀ to C ₂₀ alkyl, can be well dispersed in nonpolar polyolefin-based hot melt adhesives. Polar polyacrylic salts can be used, for example, in combination with polyurethanes.

The This object is further achieved by a method for the production solved the filter described above, wherein melt adhesive threads be spun and loaded with adsorber particles and on a carrier layer are deposited, wherein the hot melt adhesive at least one charge carrier and / or charge stabilizer and wherein the melt adhesive threads during the spinning and / or in a subsequent step electrically to be charged.

at an embodiment of the invention Method are the melt adhesive threads in a melt spinning process spun.

In one embodiment, the hotmelt adhesive is sprayed from the melt from nozzles in the direction of the support layer guided at a distance past the nozzles, wherein the hotmelt adhesive threads are loaded with adsorbent particles in the area between the nozzles and the carrier web and then the melt adhesive threads loaded with adsorbent particles are deposited on the carrier layer become. Such a method is for example in the DE 198 45526 A1 , the disclosure of which is hereby incorporated by reference. Alternatively, the hot melt adhesive can also be sprayed from the solution to form melt adhesive threads.

simultaneously with spinning or directly afterwards, the charge separation done on the spun threads.

The charge separation can also be carried out on the finished filter. In this case, the melt-adhesive threads before and / or during an electric field, of preferably 0.01-100 kV / m, more preferred from 0.5 to 50 kV / m, are heated to a temperature which allows charge separation in the melt adhesive filaments, for example by dissociation of charges, and is then cooled to a temperature at which the separated charges in the melt adhesive filaments is stabilized. Charge separation is allowed at temperatures above the softening range, preferably above the softening point of the melt adhesive threads. A stabilization of the charge separation in the melt adhesive threads is allowed at temperatures below the softening point of the melt adhesive threads, since the separate charges are fixed at temperatures below the softening point.

In one embodiment of the method according to the invention, the melt adhesive threads are spun in an electrospinning process. For this purpose, a web-shaped material is passed between two electrodes and thereby charged electrostatically, wherein the spray-off electrode and / or the receiving electrode are electrically charged. Such Elektrospinnverfahren is for example in the DE 2328015 A1 described which is incorporated by reference.

at an embodiment of the invention Process become the adsorbent loaded with adhesive melt adhesive threads on the substrate to a random three-dimensional Network filed.

The Carrier layer, the melt adhesive threads and / or the adsorbent particles of the process according to the invention will be in accordance with the above for the filter material selected definitions and / or manufactured.

at One embodiment, the melt adhesive threads sprayed from a nozzle and between the nozzle and carrier fleece on which the melt adhesive threads be stored loaded with adsorbent particles. The distance is chosen so that the melt adhesive threads still a have some stickiness. Preferably, the Distance between the nozzles and the supply of Adsorberpartikel 1 to 20 cm, preferably 3 to 10 cm, more preferably 2 to 5 cm. Preferably, the spray forms with the surface the carrier layer an acute angle of preferably 20 to 45 °. The supply of Adsorberpartikel preferably takes place via a shaker.

at one embodiment is to stretch the fibers Compressed air used. This creates a stream of air, so that trickling Adsorberpartikel along the sprayed melt adhesive threads stick to it. Subsequently, the with adsorbent particles laden melt adhesive threads on the past Deposited carrier layer, wherein preferably the melt adhesive threads on a cushion created by air on the carrier layer be filed. This air cushion prevents there is no tight bond between fibers and adsorbers. The Adsorberpartikel remain rather in a kind of loose three-dimensional Fiber network suspended.

characters

1 shows a diagram of the NaCl removal efficiency for polyester filter material with a polyamide coating (Colback ^®, Colbond, The Netherlands) with various carriers and / or charge stabilizers and various Adsorberpartikelgrößen, wherein the melt adhesive threads during spinning by applying a negative voltage of -7.5 kV to the Aufsprühelektrode were charged.

2 shows a diagram of the NaCl removal efficiency for polyester filter material (Colback ^®, Colbond, The Netherlands) with various carriers and / or charge stabilizers and various Adsorberpartikelgrößen, wherein the melt adhesive threads during spinning by applying a negative voltage of -5.0 kV to the Aufsprühelektrode and a positive Voltage of + 5.0 kV were charged to the spray head.

3 shows a diagram of the NaCl removal efficiency for polyester filter material (Colback ^®, Colbond, The Netherlands) with various carriers and / or charge stabilizers and various Adsorberpartikelgrößen, wherein the melt adhesive threads by applying a negative voltage of -5.0 kV to the Aufsprühelektrode and a positive voltage of + 5.0 kV were charged to the spray head, and the measured samples were stored in an oven at 60 ° C overnight prior to measurement.

By The following example is intended to further illustrate the present invention explained, but in no way be limited.

Example:

Each 50 g of polyolefin-based melt adhesive was melted in a beaker on a hot plate and with vigorous stirring, the amounts of the respective charge carriers or charge stabilizers specified below were added. Charge stabilizer or charge carrier Addition I [g] Addition II [g] Addition III [g] tetrabutylammonium 2.11 1.06 0.53 tetradecyl 2.21 1.10 0.55 Tetra kis (decyl) ammonium bromide 4.32 2.16 1.08 sodium 2.00 1.00 0.50 barium titanate 0.76 0.38 0.19 Polyacrylic Acid Sodium Salt 5 '100 (19% Na) (Fluka) 0.50 0.25 0.12

There were measured for each charge carriers or charge stabilizer and at each concentration produced in each case two approximately DIN A4 wide spray pattern on the polyester carrier medium (Colback ^®, Colbond, The Netherlands) with the addition of activated charcoal granules having a grain size distribution of 30 x 70 mesh by even a negative voltage of -7.5 kV applied to the Aufsprühelektrode ( 1 ) and in the second experiment the spray electrode at -5 kV and the spray head at +5 kV ( 2 ) was loaded. Adsorption filter layers having an approximate basis weight laydown of 150 g / m ^{2 were} produced.

From the spray patterns, two punched pieces each with a diameter of 12 cm were taken and measured in the flow channel, the Natriumchloridabscheideleistung at a media speed of 16.6 cm / s with NaCl particles in the size range of 0.3 to 5 microns. The medium used was air. The measurement was made according to DIN 71460-1 carried out.

One punched product was stored at about 60 ° C overnight in the oven, the other was stored at room temperature. The separation efficiency determination was repeated the next day and the increase and decrease in the filtration efficiency of the aged samples was determined ( 3 ).

Result:

FAG

= (Fraktionsabscheidegrad)

C_Rein(x)

= Partikelkonzentration (Teilchen/m³) im gereinigten Meßgas nach dem Durchströmen des Filters in Abhängigkeit von der Partikelgröße.

C_Roh(x)

= Partikelkonzentration (Teilchen/m³) im Meßgas vor dem Durchströmen des Filters in Abhängigkeit von der Partikelgröße.

In the case of a negative charge of the sputtering electrode at -7.5 kV, in particular with NaCl particle sizes in the range of 1 to 5 .mu.m and with the use of sodium oleate, 0.5 g as charge stabilizer or charge carrier per 50 g hotmelt adhesive a significantly improved filtration effect was obtained. The fractional efficiency is indicated on the Y-axis.

FAG

= (Fraction separation efficiency)

C _{pure (x)}

= Particle concentration (particles / m ³ ) in the purified measuring gas after flowing through the filter as a function of the particle size.

C _{raw (x)}

= Particle concentration (particles / m ³ ) in the measuring gas before flowing through the filter as a function of the particle size.

In Another experiment was the Aufsprühelektrode with -5 kV and the spray head charged with + 5 kV. Again, pointed Filter materials with sodium oleate containing fibers (0.5 g) significantly improved separation efficiency. Even after aging at 60 ° C overnight were at particle sizes from 1 to 5 μm in combination with sodium oleate 0.5 g per 50 g melt adhesive significantly improved deposition values for obtained the filter materials.

Regarding the aging behavior had filter materials with polyacrylic acid sodium salt 0.25 g as charge stabilizer or charge carrier per 50 g melt adhesive after aging particularly advantageous values.

QUOTES INCLUDE IN THE DESCRIPTION

This list The documents listed by the applicant have been automated generated and is solely for better information recorded by the reader. The list is not part of the German Patent or utility model application. The DPMA takes over no liability for any errors or omissions.

Cited patent literature

• - DE 19845526 A1 [0002, 0046]
• - DE 10109474 C1 [0002]
• - DE 10249998 B3 [0003]
• DE 2328015 A1 [0049]

Cited non-patent literature

• - DIN 71460-1 [0060]

Claims (23)

Filter material comprising a carrier layer and an adsorption filter layer, wherein the adsorption filter layer of adsorbent loaded with hot melt adhesive threads is formed, further wherein the melt adhesive threads charge carriers and / or charge stabilizers and the melt adhesive threads have a charge and / or are rechargeable. Filter material according to claim 1, wherein the adsorbent particles with no more than 30% of the outer surface adhere to the melt adhesive threads. Filter material according to one of the preceding claims, wherein the adsorbent loaded with adhesive melt adhesive threads form a regular, three-dimensional network. Filter material according to one of the preceding claims, wherein the carrier layer consists of a nonwoven on polyester, Polyolefin, polycarbonate, polyurethane, polyamide base, from reticulated PUR foam and / or mixtures thereof is formed. Filter material according to one of the preceding claims, wherein the melt adhesive threads are made of materials of the group, consisting of polyester, polyolefin, polycarbonate, polyurethane, Polyamide-based and mixtures thereof is selected. Filter material according to one of the preceding claims, wherein the hot melt adhesive components are polymer-uniform to the carrier layer are. Filter material according to one of the preceding claims, the adsorbent particles being selected from the group consisting of zeolites, Silica gels, activated charcoal, alumina, calcium chloride and mixtures thereof are selected. Filter material according to one of the preceding claims, wherein the adsorber particles are contained in an amount of 100 to 1500 g / m ² in the adsorbent layer. Filter material according to one of the preceding claims, wherein the adsorbent particles have an average particle diameter in the Range of 50 microns to 5 mm, preferably 100 microns to 1 mm. Filter material according to one of the preceding claims, wherein the melt adhesive threads have a thickness in a range from 5 μm to 50 μm. Filter material according to one of the preceding claims, wherein the diameter of the melt adhesive threads at least by a factor of 10 smaller than the diameter of the adsorber particles. Filter material according to one of the preceding claims, the proportion of hotmelt adhesive components being 2 to 10% by weight, based on the total weight of adsorber, is. Filter material according to one of the preceding claims, wherein the charge stabilizers and / or charge carriers from the group consisting of organic and inorganic salts, salt-like compounds, ionic polymers, halogenated, in particular fluorinated hydrocarbons, organometallic complex compounds, in particular metallocenes, half-sandwich complexes, dyes, in particular Azo dyes, compounds with an extended H-electron system and mixtures thereof are selected. Filter material according to one of the preceding claims, wherein the charge stabilizers and / or charge carriers in an amount of 0.1 to 10 wt .-%, based on the weight of Melt adhesive threads, in the melt adhesive threads are distributed. Filter material according to one of the preceding claims, wherein the charge stabilizer and / or the charge carrier to the melt adhesive threads is compatible. Filter according to one of the preceding claims, a cover layer which faces away from the carrier layer Side of the adsorbent layer is arranged, wherein the cover layer a filter effect for dust particles larger than 3 μm. Filter comprising a filter material after a of the preceding claims. Method for producing a filter material, wherein melt adhesive threads are spun with Adsorberpartikel be loaded and stored on a carrier layer, wherein the hotmelt adhesive comprises at least one charge stabilizer and / or charge carrier contains and wherein the melt adhesive threads during spinning and / or in a subsequent step electrically to be charged. The method of claim 18, wherein the melt adhesive threads be spun in an electrospinning process, wherein the spray-off electrode and / or the receiving electrode are electrically charged. The method of claim 18, wherein the melt adhesive threads after depositing the melt adhesive threads in an electric Field to be charged. The method of claim 20, wherein the melt adhesive threads, before and / or while an electric field is applied, be heated to a temperature which is a charge separation allowed in the melt adhesive threads, and subsequently be cooled to a temperature at which the separated Charge is stabilized in the melt adhesive threads. Method according to one of claims 18 to 21 for producing a filter material according to a of claims 1 to 17. Use of the filter material according to one of the claims 1 to 17 as cabin air filter, circulating air filter, clean room filter, exhaust air filter, Housing filter and / or vacuum cleaner filter.