FILTER MEDIUM WITH ANTI-ALLERGENIC SUBSTANCES

Description

[0001] The invention relates to a filter medium according to the preamble of claim 1. The invention also relates to a filter element with such a filter medium according to claim 7. State of the art

[0002] A multi-layered filter medium is already known from DE 10 2013 021 071 A1, which comprises an anti-allergenic filter layer, an antimicrobial filter layer, a particle filter layer, and an odor filter layer. The anti-allergenic filter layer is often located on the outer surface of the filter medium to ensure good release of the anti-allergenic substances. A disadvantage of this design is that the long-term effectiveness of the anti-allergenic filter layer is difficult to guarantee. US 2019 / 329171 A1 discloses a filter medium that exhibits low repulsion when folded, possesses excellent air and water permeation resistance and filtration performance, and exhibits low pressure drop even with a high adsorbent loading of the folded filter medium.

[0003] According to current technology, the anti-allergenic layer is created by impregnating, coating, fouling, slapping, or dipping filter layers with anti-allergenic substances. A disadvantage of this method is the complex process technology.

[0004] Another filter medium is described in EP 3 162 425 A1. Multilayer filter media with liquid-applied antiallergens are described in DE 10 2013 021 071 A1 and WO 2014 / 019660 A1. Multilayer filter media with a functional layer of activated carbon granules are described in DE 10 2005 037 671 B3 and EP 0 818 230 A1, respectively. Task

[0005] The object of the present invention is to create a filter medium which has improved anti-allergenic properties and is easier to manufacture and handle. Technical solution

[0006] This problem is solved by a filter medium having the features of claim 1.

[0007] According to the invention, it was found to be advantageous to provide the anti-allergenic substances in the form of a free-flowing or pourable solid: The filter medium according to the invention has a functional layer and two nonwoven layers, wherein the functional layer is arranged between the two nonwoven layers. A nonwoven is understood here to mean, in particular, a nonwoven as defined in DIN EN ISO 2019-08.

[0008] The functional layer of the filter medium contains anti-allergenic substances. These substances serve to modify, for example, the finest pollen particles and other allergens that cannot be completely retained by the nonwoven layers of the filter medium, rendering them harmless to the human immune system. According to the invention, the anti-allergenic substances are incorporated into the functional layer in the form of a free-flowing or pourable solid. This free-flowing or pourable solid can be sprinkled in dry during the manufacturing process of the filter medium. Such a filter medium thus offers the advantage of simple production, as the free-flowing or pourable solid is easy to handle. Furthermore, the structure of the filter medium protects the functional layer with its two outer layers of nonwoven fabric, providing good protection against mechanical stress.A further advantage of the filter medium according to the invention lies in its high degree of environmental and human compatibility, since components of the functional layer cannot escape over the product life cycle, including the disposal of the filter medium. A further advantage arises from the fact that the anti-allergenic substances, due to their central positioning in the functional layer, can be released slowly and evenly.

[0009] In the filter medium according to the invention, the solid is a granulate, also referred to as granular matter or granular medium. A granulate is understood to be a powder, sphere, particle, dust, or grain form, particularly with a granule diameter of 200–700 µm—also referred to as grain size. With coarser granules, a uniform distribution of the anti-allergenic substances across the surface of the filter medium would no longer be guaranteed. The anti-allergenic substances are present, in particular, at a concentration of 2–250 g / m², and especially preferably at a concentration of 20–25 g / m² when using citric acid. This ensures good anti-allergenic efficacy of the filter medium.

[0010] According to one variant, the anti-allergenic substances in the filter medium can contain polyphenols, such as catechins, flavonoids, and tannins, such as tannic acid. In another variant, the anti-allergenic substances in the filter medium can contain fruit acids, such as citric acid.

[0011] The functional layer contains adsorptive substances in the form of a free-flowing or pourable solid, particularly activated carbon. Surprisingly, it was found that the adsorption capacity of activated carbon mixed with citric acid granules in a functional layer is no worse than when using pure activated carbon. The inclusion of adsorptive substances also allows the filter medium to adsorb unwanted or toxic gases.

[0012] The functional layer may also contain substances for scenting the airflow passing through the filter medium. Such substances can include, for example, citronellal, citronellol, ethyl vanillin, and limonene.

[0013] While these substances are normally present in liquid form under the climatic operating conditions of the filter medium, they can be absorbed, for example, by solids based on silica gel, zeolites and superabsorbents, so that the odorant is present as a free-flowing or pourable solid.

[0014] The functional layer may also contain antimicrobial substances, such as metals or metal compounds, which prevent the filter medium from being attacked by microorganisms, such as fungi, mold, bacteria or algae.

[0015] Two alternatives are conceivable for setting up the functional location.

[0016] According to a first alternative, the functional layer consists of a layer of a mixture of antiallergens and adsorptive substances. That is, the free-flowing or pourable solids containing the antiallergenic and adsorptive substances are mixed together and form a layer that can also be described as a substrate layer. If additional fragrance and / or antimicrobial substances are included, these can also be incorporated into the mixture. In a second variant, the functional layer has at least two layers: one layer of antiallergenic substances and another layer of adsorptive substances. If fragrance and / or antimicrobial substances are also included, these can form part of the functional layer in further layers.

[0017] In further development of the filter medium, the substances of the functional layer are bonded to each other and to the nonwoven layers using an adhesive. The adhesive can be, for example, in the form of hot melt adhesive beads or as fine adhesive threads applied by spraying.

[0018] In a particularly advantageous and therefore preferred embodiment of the filter medium according to the invention, at least one nonwoven layer possesses hydrophilic properties and / or at least one nonwoven layer possesses hydrophobic properties. This allows control over how much moisture penetrates the functional layer and releases the anti-allergenic substances, and how quickly. A corresponding hydrophilic or hydrophobic property of the nonwoven layers ensures a slow and uniform release of the anti-allergenic substances. The hydrophilic or hydrophobic properties of the nonwoven layers can be achieved, among other things, by the type of bonding, by impregnation, and by selecting a suitable material. For example, nonwovens made of polycarbonate (PC) have hydrophilic properties, and those made of polypropylene (PP) have hydrophobic properties, depending particularly on the water absorption capacity of the base material.

[0019] The invention also relates to a filter element with a filter medium as described above, which serves for air filtration in a ventilation system of a mobile device, in particular of a vehicle, a ship or an aircraft.

[0020] The described invention and the described advantageous embodiments of the invention, even when combined with one another, represent advantageous developments of the invention, insofar as this is technically feasible. For further advantages and structurally and functionally advantageous embodiments of the invention, reference is made to the dependent claims and the description of exemplary embodiments with reference to the accompanying figures. Example of implementation

[0021] The invention will be explained in more detail with reference to the attached figures. Corresponding elements and components are identified by the same reference numerals in the figures. For the sake of clarity, the figures are not drawn to scale.

[0022] They show in schematic representation Fig. 1 a filter medium not according to the invention with a functional layer containing anti-allergenic substances and two nonwoven layers. Fig. 2 a filter medium with a functional layer containing anti-allergenic and adsorptive substances and two nonwoven layers. Fig. 3 a further embodiment of a filter medium with a functional layer containing anti-allergenic and adsorptive substances and two nonwoven layers. Fig. 4 a filter element with a pleated filter medium.

[0023] Fig. 1 Figure 1 shows a first embodiment of a filter medium 10, which is not according to the invention and serves to filter an airflow L. The filter medium 10 has two nonwoven layers 1 and a functional layer 2 arranged between them. The functional layer 2 contains an anti-allergenic substance 3, which is in the form of a free-flowing solid, namely a granulate.

[0024] In the embodiment of the filter medium 10 according to Fig. 2 Functional layer 2 has two layers: a first layer containing anti-allergenic substances 3 and a second layer containing adsorptive substances 4. These adsorptive substances can be, for example, activated carbon. The adsorptive substances are also in the form of a free-flowing or pourable solid, particularly in the form of granules. The substances in functional layer 2 are bonded to each other and to the nonwoven layers 1 by means of adhesive 5.

[0025] As in Fig. 3 As shown, the functional layer 2 of the filter medium 10 can have a layer of a mixture of anti-allergenic and adsorptive substances 3, 4. The anti-allergenic substances 3 and the adsorptive substances 4 together form a substrate layer which is arranged between the nonwoven layers 1.

[0026] In Fig. 4 Figure 1 shows a section of a filter element 100. The filter medium 10 has been pleated and provided with folded edges 20, so that it has a larger filtration area. Such a filter element 100 can additionally be provided with edge bands or frames (not shown) and can be used in ventilation systems of mobile equipment, for example in vehicles, ships or aircraft. Reference symbol list

[0027] 1 Non-woven layer 2 Functional layer 3 Anti-allergenic substance as granules 4 Adsorptive substance as granules 5 Adhesive 10Filter medium 20Folded edge 100Filter element Airflow

Claims

1. Filter medium (10) having a functional ply (2) and two nonwoven fabric plies (1), the functional ply (2) being arranged between the nonwoven fabric plies (1) and the functional ply (2) containing antiallergenic substances, characterized in that the antiallergenic substances are in the form of a pourable or free-flowing solid (3) and the solid is a granular material (3), and the functional ply (2) contains adsorptive substances (4) in pourable or free-flowing form, in particular activated carbon, the functional ply (2) - having a layer of a mixture of antiallergenic and adsorptive substances (3, 4), or - having two layers, with a first layer of antiallergenic substances (3) and a second layer of adsorptive substances (4).

2. Filter medium according to one of the preceding claims, characterized in that the antiallergenic substances (3) contain polyphenols or fruit acids.

3. Filter element according to one of the preceding claims, characterized in that the functional ply (2) contains substances for scenting.

4. Filter medium according to one of the preceding claims, characterized in that the functional ply (2) contains antimicrobial substances.

5. Filter medium according to one of the preceding claims, characterized in that the substances of the functional ply (2) are bonded to each other and to the nonwoven fabric plies (1) by means of an adhesive (5).

6. Filter medium according to one of the preceding claims, characterized in that at least one nonwoven fabric ply (1) has a hydrophilic property and / or at least one nonwoven fabric ply (1) has a hydrophobic property.

7. Filter element (100) having a filter medium (10) according to one of the preceding claims for air filtration in a ventilation system of a mobile machine, in particular a vehicle, ship or aircraft.