Filter medium

Abstract

The invention describes a filter medium (10), in particular for an air filter, in particular an interior air filter or for a fuel cell, including at least three active layers: a catalytic active layer (12) comprising catalytic activated carbon particles (12a), a second active layer (14) comprising impregnated or catalytic activated carbon particles (14a), a third active layer (16) comprising impregnated or catalytic activated carbon particles (16a), wherein at least one active layer comprises impregnated activated carbon particles and the three active layers (12, 14, 16) differ from one another.

The invention further discloses a filter media body including the filter medium; a filter element including the filter media body or the filter medium; an air filter including the filter element or the filter media body or the filter medium, and a production method for producing the filter medium.

Claims

1. A filter medium for an air filter, comprising at least three active layers: a catalytic active layer comprising catalytic activated carbon particles; a second active layer comprising impregnated or catalytic activated carbon particles; and a third active layer comprising impregnated or catalytic activated carbon particles, wherein at least one active layer comprises activated carbon particles, and wherein the at least three active layers differ from one another.

2. The filter medium according to claim 1, wherein the second active layer comprises impregnated activated carbon particles.

3. The filter medium according to claim 2, wherein the catalytic active layer comprises activated carbon particles for removing acidic (pH<7) and/or hydrophilic gases.

4. The filter medium according to claim 3, wherein the catalytic activated carbon particles are adhesively cross-linked and bonded together by an adhesive.

5. The filter medium according to claim 2, wherein the second active layer comprises impregnated activated carbon particles for removing ammonia.

6. The filter medium according to claim 2, wherein the second active layer comprises phosphoric-acid-impregnated activated carbon particles.

7. The filter medium according to claim 6, wherein the phosphoric-acid-impregnated activated carbon particles are adhesively cross-linked and bonded together by an adhesive.

8. The filter medium according to claim 2, wherein the third active layer comprises impregnated activated carbon particles for removing ammonia and formaldehyde.

9. The filter medium according to claim 2, wherein at least some of the impregnated activated carbon particles of the third active layer are impregnated with ethylene urea and phosphoric acid.

10. The filter medium according to claim 9, wherein the impregnated activated carbon particles are adhesively cross-linked and bonded together by an adhesive.

11. The filter medium according to claim 1, wherein the filter medium comprises at least one support layer.

12. The filter medium according to claim 11, wherein the filter medium comprises at least one filtration layer.

13. A filter media body comprising: a filter medium according to claim 12; and at least one lateral band and/or at least one top band.

14. A filter element comprising: a filter media body according to claim 1; a frame; at least one retaining element and/or at least one seal.

15. An air filter comprising: a filter element according to claim 14; and a housing.

16. A method for producing a filter medium according to any of claim 11, including the following steps: providing a support layer; applying a catalytic, first active layer comprising catalytic activated carbon particles onto the support layer; applying a second active layer comprising impregnated or catalytic activated carbon particles to the first active layer; applying a third active layer comprising impregnated or catalytic activated carbon particles to the second active layer, wherein a sequence of the applying steps of the first, second and third active layer is selected so as to be interchangeable; and applying a further support layer onto a last-applied activated carbon layer.

17. The method according to claim 16, wherein at least one of the active layers comprises impregnated activated carbon particles.

18. The method according to claim 16, wherein, in sequence, the catalytic, first active layer having catalytic activated carbon particles is applied onto the support layer; then the second active layer comprising impregnated or catalytic activated carbon particles is applied to the first active layer; and finally the third active layer comprising impregnated or catalytic activated carbon particles is applied to the second active layer.

19. The method according to claim 18, further comprising the step of: applying an adhesive before each active layer is applied.

20. The method according to claim 19, further comprising the step of: applying at least one further at least one further support layer.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0067] In the drawings:

[0068] FIG. 1 is a highly simplified sectional view of a filter medium according to one embodiment.

DETAILED DESCRIPTION

[0069] FIG. 1 shows a filter medium 10, in particular for an air filter, in particular an interior air filter or for a fuel cell, the filter medium comprising a catalytic outer active layer 12 comprising catalytic activated carbon particles 12a, a second, middle active layer 14 comprising impregnated activated carbon particles 14a and a third, outer active layer 16 comprising impregnated or catalytic activated carbon particles 16a, wherein at least one active layer, for example the third active layer 16, comprises impregnated activated carbon particles 16a. The catalytic activated carbon particles 12a of the catalytic active layer 12, which is an outer layer in FIG. 1, of the filter medium 10 can, as shown schematically in FIG. 1, also be bonded, in particular cross-linked, by the addition of adhesive 18. The adhesive 18 can advantageously be a reactive hot-melt adhesive, for example based on polyurethane. The adhesive 18 can also advantageously connect a filtration layer 20, in particular a particle filtration layer 20, to the catalytic active layer 12. The catalytic activated carbon particles 12a of the catalytic active layer 12 can have an area density of from 50 to 300 g/m.sup.2, in particular 150 to 300 g/m.sup.2. The catalytic active layer 12 advantageously comprises catalytic activated carbon particles 12a for removing acidic (pH<7) and/or hydrophilic gases, and thus removes hydrophilic gases and additionally adsorbs some of the water found in the gas stream. This allows the gas stream to be easily dried before passing through an active layer, for example the second active layer 14, designed for basic and/or organic, in particular hydrophobic gases and odorants, in particular hazardous or reactive gaseous substances, as a result of which the adsorption power is additionally optimized for basic and/or organic, in particular hydrophobic gases and odorants hazardous or reactive gaseous substances.

[0070] The impregnated activated carbon particles 14a of the second active layer 14 of the filter medium 10 can, as shown schematically in FIG. 1, also be bonded, in particular cross-linked, by the addition of adhesive 18. The adhesive 18 can advantageously be a reactive hot-melt adhesive, for example based on polyurethane. Advantageously, the second active layer 14 comprises impregnated activated carbon particles 14a for removing ammonia, in particular phosphoric-acid-containing particles 14a. The phosphoric acid impregnation induces chemisorption of ammonia from the gas stream to be purified. For example, the impregnation can consist of 2 to 15 wt. %, in particular 3.5 to 15 wt. %, in particular 2 to 6 wt. % phosphoric acid.

[0071] The chemisorption allows for more tightly bonded chemical bonds to the adsorbent compared with physisorption, as a result of which the ammonia is particularly advantageously bonded. Particularly advantageously, the impregnated activated carbon particles 14a of the second active layer 14 have an area density of from 50 to 300 g/m.sup.2, in particular 50 to 150 g/m.sup.2. The area density can easily be adapted to the moisture content of the active layer and the environment of the gas stream, which means a smaller amount of adhesive is required in order to bond, in particular to cross-link, the impregnated activated carbon particles 14a. By adapting the area density, a favorable carbon-to-adhesive ratio is thus additionally achieved. The second active layer 14 is particularly advantageously arranged as the middle layer between the catalytic outer active layer 12 and the third, outer active layer 16.

[0072] The impregnated activated carbon particles 16a of the second active layer 16 of the filter medium 10 can, as shown schematically in FIG. 1, also be bonded, in particular cross-linked, by the addition of adhesive 18. The adhesive 18 can advantageously be a reactive hot-melt adhesive, for example based on polyurethane. The adhesive 18 can also advantageously connect a particle filtration layer 20 to the first active layer 12. The third active layer 16 can in particular comprise impregnated activated carbon particles 16a for removing ammonia and formaldehyde. The third active layer 16 can comprise activated carbon particles 16a impregnated with ethylene urea and phosphoric acid, for example. The impregnated activated carbon particles 16a of the third active layer 16 can have an area density of from 50 to 300 g/m.sup.2, in particular 50 to 150 g/m.sup.2. The impregnation can consist of 2 to 15 wt. %, in particular 3.5 to 15 wt. %, in particular 2 to 6 wt. % phosphoric acid and 10 to 20 wt. % ethylene urea, for example.

[0073] The filter medium 10 can additionally comprise a support layer 22, in particular a textile support layer 22, in particular a support layer 22 formed as a non-woven fabric.

[0074] The filter medium 10 can additionally comprise a filtration layer 20, in particular formed as a textile particle filter layer 20, in particular formed as a non-woven fabric.