ITMI20111046A1 - METHOD FOR THE REALIZATION OF A FILTER FOR AIR, DIE-CUT FOR THE REALIZATION OF A FILTER FOR AIR, AND AIR FILTER - Google Patents

Description

Description

"Method for making an air filter, punched for making an air filter, and air filter"

The present invention relates to a method for making an air filter, a blank from which it is possible to make an air filter, and an air filter.

Numerous filters intended for air filtering are known, which have different filtering capacities, functional to the type of environment in which the filters are installed.

For example, in the home environment, a reduction of not excessively fine dust is generally sufficient and acceptable, while in environments such as hospitals or clean rooms, filtering must be more thorough and involve not only solid particles, but also pollutants or bacteria.

In known filters, in general, the filtering power is proportional to the pressure drops suffered by the air as it passes through the filter itself. This is mainly due to the fact that the filtering action is carried out by making the air travel a tortuous path inside the filter. Therefore, in environments where high air filtration is required, particularly powerful ventilation systems are required, which are not always available.

These two opposing needs, namely that of low pressure drops and high filtering power, have led to various compromise solutions.

One of these is described in the document US 2001/0052224 A1, relating to a honeycomb-shaped air filter, in which there are several layers of overlapping corrugated paper that delimit the channels through which the 'air. The high contact surface of the ducts, suitably treated, ensures good air filtration together with low pressure drops.

This type of filter, however, is of complex construction, since the layers of paper must be mutually glued one by one, being kept in the correct relative positioning. This involves the need for special machinery and rather high production costs.

The purpose of the present invention is therefore to make available an air filter that ensures a good filtering capacity, in particular of solid particles and bacteria, in the face of limited air pressure drops, which is simple to make and which ensures reduced production costs.

This and other objects are achieved by means of a method for manufacturing an air filter according to claim 1, a blank for manufacturing an air filter according to claim 7, and an air filter according to claim 14. The dependent claims define possible advantageous embodiments of the invention.

In order to better understand the invention and appreciate its advantages, some non-limiting exemplary embodiments thereof will be described below, with reference to the attached figures, in which:

Figure 1 is a plan view of a blank according to the invention;

Figure 2 is a perspective view of the blank in Figure 1 in a particular step of the method of producing an air filter according to the invention;

figure 3 is a perspective view of the blank in figure 1 in a further particular step of the production method of an air filter according to the invention;

figure 4 is a perspective illustration of an air filter according to the invention during a particular step of the method for its realization;

figure 5 is a perspective view of a filter according to the invention;

figure 6 is a plan view of a blank according to a further possible embodiment of the invention;

Figures la and 7b are partially cut-away perspective views of corrugated cardboard elements;

Figures 8a and 8b are perspective views of a filter containment element according to a possible embodiment;

Figure 9 is a perspective view of a filter partially received in a containment element in accordance with a further possible embodiment of the invention.

With reference to the figures, an air filter is indicated with the reference 1 and a blank for making this filter 1 is indicated with the reference 2. The filter 1 is made starting from the blank 2.

In accordance with the method according to the invention, for the purposes of making the filter, a corrugated cardboard element 3 is made available, which is suitably processed to obtain the blank 2.

The expression "corrugated cardboard" in the present description and in the annexed claims refers to a particular type of cardboard, such as for example the one used for making packaging. The corrugated cardboard according to the definition used here comprises at least one corrugated layer 4, i.e. a layer in which the paper has a wave pattern (for example an approximately sinusoidal pattern), and at least one support layer 5 for the corrugated layer 4 (figures 7a and 7b). The types of paper used are preferably those common for packaging cartons. For example, for the support layer 5 it is possible to use papers chosen from the group consisting of: Havana Kraft, White Kraft, Havana Liner, White Liner, Havana Test, White Test, Suede, White Suede. For the corrugated layer, for example, papers chosen from the group composed of: Scandinavian Semichimica, Semichimica, UsoSemichimica, Wellenstoff, Medium, Fluting can be used.

According to a possible embodiment, the papers of the corrugated cardboard element are recycled papers.

The corrugated cardboard element 3 can be configured in various ways. Preferably, the corrugated cardboard element 3 comprises two support layers 5, which form as many covers for the corrugated cardboard element, respectively on a first and a second face (Figure 7a). Furthermore, the corrugated cardboard element 3 can include a plurality of overlapping corrugated layers 4, preferably with intermediate layers 6 between each corrugated layer (see for example Figure 7b, in which two overlapping corrugated layers are shown). In particular, the corrugated cardboard element 3 can be conformed according to the standards envisaged for corrugated cardboard. According to these standards, the wave of each corrugated layer can be chosen from the group composed of waves of the type: Wave K (minimum height 5 mm), Wave A (minimum height 4.5 mm), Wave B (minimum height 2 , 5 mm), Wave C (minimum height 3.5 mm), Wave E (minimum height 1.2 mm), Wave F (minimum height 0.8 mm). From the combination of corrugated layers with the aforementioned conformations, it is possible to obtain multiple-wave cartons with which to make the blank 2, such as for example cartons with Wave BC (minimum height 6 mm) or EB (minimum height 3.7 mm).

The corrugated layers 4 and the support layers 5, together with any intermediate layers 6, delimit a plurality of channels 7, preferably all parallel to each other, which develop according to directions of development of channels C, preferably straight. As will be explained in detail below, these channels are used for filtering the air by the filter 1 made starting from the cardboard element 3.

The corrugated cardboard element 3 can be made available in various shapes, depending on the shape that the filter 1 must have. In accordance with a possible embodiment, the corrugated cardboard element 3 is made available in a rectangular shape ( figure 1), preferably with the development directions of the channels C parallel to the longer sides of this rectangle and perpendicular to the shorter sides of the latter.

The method according to the invention comprises a step of making a plurality of cuts 8 in the corrugated cardboard element 3. These cuts 8 are transversal, preferably orthogonal, to the directions of development of the channels C. Due to the effect of the cuts 8, the element corrugated cardboard 3 is divided into a plurality of portions of corrugated cardboard 3 ', 3' '... adjacent. If the corrugated cardboard element 3 has the rectangular shape described above, the cuts 8 are preferably parallel to the shorter sides of this rectangle, so that also the corrugated cardboard portions 3 ', 3' '... are rectangular. Even more preferably, the cuts 8 are equidistant from each other, so that the portions of corrugated cardboard 3 ', 3' '... are of equal shape and size to each other.

As a result of the cuts 8, also the channels 7 of the corrugated cardboard element 3 are divided into the various portions of corrugated cardboard 3 ', 3' '... According to the embodiment described above, in the corrugated cardboard element 3 , following the execution of the cuts 8, each channel 7 is interrupted along the respective direction of development of the channels. Therefore, in each portion of corrugated cardboard 3 'there is a plurality of side-by-side channels (equal to the number of channels present in the corrugated cardboard element 3) aligned with the channels of the adjacent corrugated cardboard portions.

The cuts 3 are not continuous. In other words, the cuts 3 have one or more areas of discontinuity 9, ie areas in which the cut is interrupted. In this way the portions of corrugated cardboard 3 ', 3' '..., following the execution of the cuts 8, are not separated from each other, but remain connected to each other in correspondence with the discontinuity areas 9.

According to a possible embodiment, in correspondence with each cut 8 three such discontinuity areas 9 are provided, preferably in equal positions in each pair of adjacent corrugated cardboard portions. For example, it is possible to foresee a first discontinuity zone 9 'in the central position and two further discontinuity zones 9' 'and 9' '' in symmetrically opposite positions with respect to the first discontinuity zone. Of course, different arrangements of the discontinuity areas 9 can be provided with respect to what has been described above, as will be clear to the skilled person.

The discontinuity areas can be made simply by failing to make the cut 8 on the corrugated cardboard element 3 in the areas where the discontinuity areas 9 will have to exist.

The cutting step is preferably carried out on only one side of the corrugated cardboard element 3. In other words, the cuts 8 are made by means of cutting means which pass through the corrugated cardboard element 3 from a first face 10 to a second face 11. For this purpose, cutting plotters or, preferably, die-cutting machines can be used, for example. These machines are known per se and will therefore not be described here.

In accordance with an embodiment, the method according to the invention comprises a step of creasing the corrugated cardboard element 3 in correspondence with at least some of the areas of discontinuity 9. The term "creasing" means a processing of the paper or of the cardboard per se known which comprises a pressing step by means of a punch having a rounded surface, in such a way as to locally push the paper or cardboard into a groove having a thickness not less than that of the paper itself. This processing is usually carried out in correspondence with areas in which the paper or cardboard must be subjected to folding (as in the present case, as will be seen below) and has the purpose of reducing the risk of breakage due to the folding itself.

The creasing is preferably performed on one side of the corrugated cardboard element 3 only, even more preferably on the same side from which the cutting step is performed, therefore exclusively on the first 10 or second 11 face of the corrugated cardboard element 3.

Preferably, the aforementioned creasing step involves all the discontinuity areas 9 of the cuts 8, but not all the cuts 8 made in the corrugated cardboard element 3. In particular, advantageously, the creasing is carried out only between alternate pairs of portions. corrugated cardboard adjacent. With reference for example to figure 1, the creasing can be carried out between the first 3 'and the second 3' 'portion of corrugated cardboard, between the third 3' '' and the fourth 3 '' '' portion of corrugated cardboard, It is so on alternately up to the last portion of corrugated cardboard, opposite to the first 3 '. Alternatively, creasing can be carried out starting from the second pair of adjacent corrugated cardboard portions, i.e. between the second 3 '' and the third 3 '' ', between the fourth 3' '' 'and the fifth 3' '' '' and so on alternately up to the last portion of corrugated cardboard, opposite to the first 3 '.

In accordance with a possible embodiment, the method according to the invention comprises a shaping cutting step of the corrugated cardboard element 3. This shaping cutting step is such as to cut the corrugated cardboard element 3 with shaped cuts 12 in a direction transverse to the directions of development of the channels C (Figure 6). These shaped cuts 12 are equal to one or more in number, so that the corrugated cardboard element 3 is in turn divided into two or more corrugated cardboard sub-elements, each of which, in turn, includes the portions of corrugated cardboard made in the cutting phase. The shaped cuts 12 are such as to allow the separation between the corrugated cardboard sub-elements. However, they have such shapes as to provide a shape connection between the corrugated cardboard sub-elements, even when these are folded. For example, the shaped cuts can be dovetail-shaped, so as to create complementary shapes in two adjacent corrugated cardboard sub-elements.

The steps described up to now allow to make the blank 2 starting from the corrugated cardboard element 3.

In order to produce the filter 1 for filtering the air, the method according to the invention comprises a step of folding the corrugated cardboard element processed in the manner previously described, i.e. the blank 2, along the cuts 8 (figure 2) . The provision of the discontinuity areas 9 facilitates the folding operation since it keeps the corrugated cardboard portions connected together, which are already in the correct relative position that they will assume in the filter 1.

The folding step is carried out in such a way that the first 10 or the second 11 face of each portion of corrugated cardboard faces respectively the first or second face of the adjacent corrugated cardboard portion.

Preferably, the cardboard element is folded "like an accordion". In other words, with reference to Figure 2, the corrugated cardboard element is folded in such a way that for example: the second face 11 of the first corrugated cardboard portion 3 'faces the second face 11 of the second corrugated cardboard portion 3 ''; the first face 10 of the second portion of corrugated cardboard 3 '' faces the first face 10 of the third portion of corrugated cardboard 3 '' '; the second face 11 of the third portion of corrugated cardboard 3 '' 'faces the second face 11 of the fourth portion of corrugated cardboard 3' '' ', and so on.

It should be noted that, due to the folding effect, part of the paper or cardboard forming the corrugated cardboard element 3 is torn in correspondence with the discontinuity areas 9 on the opposite side with respect to the side on which the faces of the adjacent corrugated cardboard portions are face each other. For example, with reference to the figures, due to the effect of the folding step between the first 3 'and the second 3' 'portion of corrugated cardboard, the paper of the support layer 5 will tear on the first face 9 and on any intermediate layers 6 provided. , but not of the paper of the support layer 5 on the second face 11. Similarly, between the second 3 '' and the third 3 '' 'portion of corrugated cardboard there will be a tear of the paper of the support layer 5 on the second face 11 and on the any intermediate layers 6 provided, but not of the paper of the support layer 5 on the first face 10.

The described folding step allows to bring the blank 2 from an extended condition (Figure 1) to a packed condition (Figure 3), in which a plurality of side-by-side layers have channels for the passage and filtering of the air. The aforementioned side-by-side layers are made from the portions of corrugated cardboard, in which the channels 7 form the channels for the passage and filtering of the air. From the folding of the corrugated cardboard element 3, a filtering body is obtained, capable of filtering the air by passing it through its own channels 7.

Advantageously, the method according to the invention comprises a relative fixing step of the corrugated cardboard portions in the filtering body. In this way it is avoided that the filtering body can reopen, ie that the corrugated cardboard portions can move away from each other thus making the filter unusable. This fixing step can be carried out according to various methods by means of relative fixing means of different nature.

By way of example, it is possible to make available a fastening element 13 (figure 4), which is preferably also made of corrugated cardboard, having such dimensions as to wrap laterally (i.e. not on the faces at which the channels 7). For example, the fixing element 13 can be made available in an extended form and folded in correspondence with the corners of the filtering body. This fixing element 13 is preferably glued laterally to the filtering body. Even more preferably, the fastening element 13 is fixed by overlapping its two ends and gluing them together. Alternatively, these two ends can be shaped for example by means of suitable cuts in such a way that they can be coupled by means of a shape connection.

According to a possible embodiment, the method further comprises a step of making available a containment element 14 of the filtering body. The containment element 14 defines a housing compartment 15 inside which the filtering body can be inserted in a corresponding insertion step. The housing element 15 further comprises a first 16 and a second 17 opening for the passage of air. The filtering body is inserted in the housing compartment 15 in such a way that the air to be filtered can access the channels 7 and exit them once filtered through the above mentioned first 16 and second 17 outlets, put in communication with each other through the channels themselves (Figure 5).

Preferably, the containment element 14 is also made of corrugated cardboard. For example, it can be made starting from a suitably made blank. With reference to figure 8b, the containment element 14 can for example comprise a first 14 'and a second 14' 'portion connected to each other by means of a rectangular or square connecting element 18, having a thickness equal to the thickness of the filtering body. . In the first 14 'and in the second 14' 'portion of the containment element 14 the first 16 and the second 17 openings are made respectively. The filtering body is placed between the first 14 'and the second 14' 'portion of the containment element and then wrapped by the latter. It is possible to achieve a permanent closure of the containment element by means of lateral closing wings 19 arranged laterally on both the first 14 'and the second 14' 'portion of the containment element 14. These lateral closing wings 19 can be for example glued together. It should be noted that, in accordance with an embodiment, the containment element 14 can make a container for the filtering body before its use. According to this embodiment (figure 8a), the first 14 'and the second 14' 'portion of the containment element 14 are originally devoid of the first 16 and the second 17 opening, but are equipped with tear lines 20 having a corresponding to the contour of these openings, which allow material to be removed only when the filter is used.

The filter made with the methods described can be advantageously used for air filtering. For example, it can be inserted into air ducts.

In accordance with a further possible embodiment, the containment element 14 is shaped in such a way that the filtering body can be inserted inside it like a drawer, ie by sliding (figure 9). For this purpose, the containment element can have a shape substantially equal to the shape of the filtering body and delimit a space inside which it can be inserted. For example, the containment element can be shaped as a parallelepiped without one or more faces (preferably two faces), inside which the filtering body can be inserted. According to this embodiment, the filter is removed from the containment element when the filter is inserted into the air ducts.

Examples

Loss of range tests

Flow loss tests were carried out on filters made according to the invention having dimensions 503x503x50 mm (in which 50 mm represents the thickness of the filter, i.e. the length of the air path in the channels), made of corrugated cardboard with different types of wave (in particular BC, B, EB, E), using for the tests a fan with a diameter of 26 cm, flow rate 206 l / s and thrust pressure 20 Pa.

To evaluate the flow rate decrease values, measurements were carried out by means of an anemometer on the air coming out of the fan, respectively with and without filter mounted.

Compared to the situation of the fan only (206 l / s), the insertion of a filter determined the following decrease in flow rate:

- BC wave filter: 41%

- B wave filter: 50%

- EB wave filter: 55%

- E wave filter: 72%

Tests of bacterial abatement after recirculation Tests of abatement of the gaseous bacterial load were also carried out by counting the CFU (i.e. of bacterial strains forming colonies), carried out by aspirating and fluxing 0.27 m <3> of air on Petri dishes with a special sampler , keeping the plates in culture for 24 hours and finally counting the colonies present on the plates (CFU).

The values of the CFUs present were expressed as a percentage of the value measured at time 0.

The CFU reduction percentage was evaluated both after 60 minutes and after 50 air recycles (values obtained by interpolating to the average value of the previous data for a time corresponding to 50 recycles).

The results are reported below.

Percentage reduction of bacteria after 60 minutes of testing:

- fan without filter: 41.0 ± 19.5% (4 tests) - BC wave filter: 79.8% ± 10.6% (9 tests)

- B wave filter: 79.6 ± 3.8% (2 tests)

- EB wave filter: 79.8% ± 3.1% (2 tests)

- E wave filter: 76.9% ± 0.1% (2 tests) Percentage abatement of bacteria after 50 recycles:

- fan without filter: 12.8%

- BC wave filter: 59.5%

- B wave filter: 56.7%

- EB wave filter: 71.2%

- E wave filter: 74.8%

From the description provided above, the skilled person will be able to appreciate how the filter according to the invention can be made in a simple way starting from commonly used and low-cost material, ie cardboard for packaging or a similar material. The cost of making the filter is therefore low. The possibility of using recycled paper makes the filter even more economical and has a low environmental impact.

The skilled person will also be able to appreciate how the method according to the invention allows to realize filters of different dimensions, which therefore can be adapted to air ducts of various types, in a simple way. In fact, the useful filtering surface (ie the surface that in use will be oriented transversely to the direction of the air) can be increased or reduced simply by increasing or reducing the number of adjacent corrugated cardboard portions. Similarly, the thickness of the filter (proportional to or equal to the length of the path followed by the air inside the channels) can be increased or decreased simply by increasing or reducing the size of each portion of corrugated cardboard, i.e. by increasing or reducing the distance. between the cuts made on the corrugated cardboard element during the cutting phase.

Furthermore, the skilled person will be able to appreciate how the filter according to the invention has such a conformation as to guarantee a high capacity to reduce the bacterial load and low pressure drops (thanks to the linear or in any case not tortuous path that is imposed on the channels).

The skilled person, in order to satisfy specific contingent needs, can make numerous additions, modifications, or replacements of elements with other functionally equivalent to the embodiments described, without however departing from the scope of the attached claims.

Claims (21)

CLAIMS 1. Method for making an air filter (1), comprising the steps of: making available a corrugated cardboard element (3) having a first (10) and a second (11) face, comprising at least one corrugated layer (4) and at least one support layer (5) of said at least one corrugated layer (4) , such as to form in the corrugated cardboard element (3) a plurality of channels (7) which extend in a direction of development of the channels (C); - making in said corrugated cardboard element (3) a plurality of cuts (8) transversal to said direction of development of the channels (C), in such a way as to divide said corrugated cardboard element (3) into a plurality of cardboard portions corrugated (3 ', 3', 3 '' ...) and said plurality of channels (7) in a plurality of sections of channels in each of said portions of corrugated cardboard (3 ', 3', 3 '', in in which said cuts (8) have one or more areas of discontinuity (9) in which the cuts (8) are interrupted, such that adjacent corrugated cardboard portions of said plurality of corrugated cardboard portions (3 ', 3' remain between them connected; folding said corrugated cardboard element (3) along the plurality of cuts (8) so that the first (10) or the second (11) faces each of said corrugated cardboard portions (3 ', 3', 3 ' '...) faces respectively the first (10) or the second (11) face of the adjacent corrugated cardboard portion, so as to create a filtering body comprising a plurality of side-by-side layers with channels for the passage and filtering of the 'air through the filtering body itself, in which each of said portions of corrugated cardboard (3', 3 ', 3' '...) creates one of said layers and the plurality of portions of channels of each portion of corrugated cardboard ( 3 ', 3', 3 '' ...) realizes said channels for passing and filtering the air of each layer of the filtering body. 2. Method for making a filter (1) according to claim 1, comprising a step of creasing the corrugated cardboard element (3) in correspondence with one or more of said discontinuity areas (9) of the cuts (8) between said adjacent corrugated cardboard portions. Method for manufacturing a filter (1) according to claim 2, in which said creasing step is carried out exclusively on the first (10) or on the second (11) face of the corrugated cardboard element. 4. Method for making a filter (1) according to claim 2 or 3, wherein said creasing is made between alternating pairs of adjacent corrugated cardboard portions. 5. Method for making a filter (1) according to any one of the preceding claims, in which in said step of making a plurality of cuts in the corrugated cardboard element (3), the cuts (8) are made exclusively starting from the first face (10) towards the second face (10) or exclusively starting from the second face (11) towards the first face (10). 6. Method for manufacturing a filter (1) according to any one of the preceding claims, further comprising a cutting step for shaping the corrugated cardboard element (3) transversely to said direction of development of the channels (C), such to divide the corrugated cardboard element into at least a first and a second corrugated cardboard sub-element, said shaping cutting step being such as to shape said at least one first and second corrugated cardboard sub-element so as to allow them to be connected in form. 7. Blank (2) for making an air filter (1), comprising a corrugated cardboard element (3) with a first (10) and a second (11) face, having at least one corrugated layer (4 ) and at least one support layer (5) of said at least one corrugated layer (4), such as to form in the corrugated cardboard element (3) a plurality of channels (7) which extend according to a direction of development of the channels ( C), wherein said corrugated cardboard element (3) comprises a plurality of cuts (8) transversal to said direction of development of the channels (C), such as to divide the corrugated cardboard element (3) into a plurality of portions of corrugated cardboard (3 ', 3' ', 3' '' ...) and said plurality of channels (7) in a plurality of sections of channels in each of said portions of corrugated cardboard (3 ', 3' ', 3 '' '...), in which said cuts (8) have one or more areas of discontinuity (9) in which the cuts (8) are interrupted, such that adjacent portions of corrugated cardboard of said multiple portions of corrugated cardboard (3 ', 3' ', 3' '' ...) remain connected, in which said corrugated cardboard element (3) can be folded along the multiple cuts ( 8) in such a way that the first (10) or the second (11) face of each of said corrugated cardboard portions can face respectively the first (10) or the second (11) face of the adjacent corrugated cardboard portion. 8. Blank (2) according to claim 7, wherein said corrugated cardboard element (3) is creased in correspondence with one or more of said discontinuity areas (9) of said cut between at least some of said corrugated cardboard portions adjacent. 9. Blank (2) according to claim 8, wherein said corrugated cardboard element (3) is creased between alternating pairs of adjacent corrugated cardboard portions. Blank (2) according to any one of claims 7 to 9, comprising at least one shaped end such as to allow a shaped connection of the blank (2) with a further corrugated cardboard element having a complementarily shaped end. 11. Blank (2) according to any one of claims 7 to 10, wherein said corrugated cardboard element (3) comprises a plurality of overlapping corrugated layers (4). Blank (2) according to claim 11, wherein the corrugated layers of said plurality of superimposed corrugated layers have waves with different amplitudes. 13. Blank (2) according to any one of claims 7 to 12, wherein said corrugated cardboard element (3) is made of recycled paper. 14. Air filter (1) comprising a corrugated cardboard element (3) with a first (10) and a second (11) face, having at least one corrugated layer (4) and at least one support layer (5) of said at least one corrugated layer (4), such as to form in the corrugated cardboard element (3) a plurality of channels (7) which extend according to a direction of development of the channels (C), in which said corrugated cardboard element (3) comprises a plurality of cuts (8) transversal to said direction of development of the channels (C), such as to divide the corrugated cardboard element (3) into a plurality of portions of corrugated cardboard (3 ', 3 '', 3 '' '...) and said plurality of channels (7) in a plurality of sections of channels in each of said portions of corrugated cardboard (3', 3 '', 3 '' '... ), in which said cuts (8) have one or more areas of discontinuity (9) in which the cuts (8) are interrupted, such that adjacent corrugated cardboard portions of said plurality of corrugated cardboard portions to (3 ', 3' ', 3' '' ...) remain connected, in which said corrugated cardboard element (3) is folded along the plurality of cuts (8) so that the first ( 10) or the second (11) face of each of said portions of corrugated cardboard (3 ', 3' ', 3' '' ...) faces respectively the first (10) or the second (11) face of the adjacent corrugated cardboard portion, so as to create a filtering body comprising a plurality of side-by-side layers with channels for the passage and filtering of the air through the filtering body itself, in which each of said corrugated cardboard portions (3 ', 3 '', 3 '' 'realizes one of said layers and the plurality of sections of channels of each of said portions of corrugated cardboard (3', 3 '', 3 '' '...) realizes said passage and filtering channels of each layer of the filter body. 15. Air filter (1) according to claim 14, wherein said corrugated cardboard element (3) is creased in correspondence with one or more of said discontinuity areas (9) between at least some of said cardboard portions corrugated adjacent. Air filter (1) according to claim 14 or 15, wherein said corrugated cardboard element (3) is creased between alternating pairs of said adjacent corrugated cardboard portions. 17. Air filter (1) according to any one of claims 14 to 16, comprising at least a first and a second corrugated cardboard sub-element adjacent at their ends, each comprising said plurality of corrugated cardboard portions {3 ' , 3 '', 3 '' ', said first and second corrugated cardboard sub-element being interconnected by means of a shape coupling. 18. Air filter (1) according to any one of claims 14 to 17, comprising means for the relative fixing of said portions of corrugated cardboard (3 ', 3' ', 3' '' ...) in said filter body . 19. Air filter (1) according to any one of claims 14 to 42- 48, wherein said corrugated cardboard element (3) comprises a plurality of overlapping corrugated layers (4). 20, Air filter (1) according to claim 1_9, wherein the corrugated layers of said plurality of overlapping corrugated layers have waves with different amplitudes. 21. Air filter (1) according to any one of claims 14 to 20, wherein said corrugated cardboard element is made of recycled paper.