ZIGZAG-FOLDED NONWOVEN MATERIAL

Abstract

The invention relates to a method for producing a zigzag-folded nonwoven material for a filter, wherein the nonwoven material is produced by a melt-spinning process, comprising the following work steps: folding the nonwoven material by means of a folding device, whereby a plurality of folds results, wherein the folds divide the nonwoven material into first limbs and second limbs such that the nonwoven material is folded in zigzag form; and subsequently welding a weld region of the first limb of a fold to at least one weld region of the second limb of a fold by means of a thermal-contact welding process, wherein a welded joint is formed between the two facing sides of the limbs of a fold. The invention furthermore relates to a corresponding apparatus and a corresponding nonwoven material.

Claims

1. A method for producing a zigzag-folded nonwoven material for a filter, wherein the nonwoven material is produced by a melt-spinning process, comprising the following work steps: folding the nonwoven material by means of a folding device, whereby a plurality of folds results, wherein the folds divide the nonwoven material into first limbs and second limbs such that the nonwoven material is folded in zigzag form; and subsequently welding a weld region of the first limb of a fold to at least one weld region of the second limb of a fold in a plastic welding process, wherein a welded joint is formed between the two facing sides of the limbs of a fold.

2. The method according to claim 1, wherein during the welding a heating element or a plurality of heating elements enter(s) between the limbs of a fold and heats the weld regions whereby the weld regions come into contact or are brought into contact as the heating element exits and form at least one welded joint, in particular a weld seam.

3. The method according to claim 1, wherein folds are welded on both sides of the nonwoven material.

4. The method according to claim 1 further comprising the following work step: embossing at least one bulge in the first limb and/or at least one bulge in the second limb of a fold such that the bulges face one another.

5. The method according to claim 1, wherein the heating element enters between the limbs at least substantially in a direction perpendicular to the direction of manufacture of the nonwoven material and wherein an average travel speed value of the heating element is greater, preferably 10 to 100 times greater, than a travel speed of the already folded nonwoven material in the direction of manufacture.

6. The method according to claim 5, wherein the heating element additionally moves in the direction of manufacture of the nonwoven material.

7. An apparatus for producing a zigzag-folded nonwoven material for a filter, and/or for realizing a method according to claim 1, which comprises: at least one folding device configured to form a plurality of folds which divide the nonwoven material into first limbs and second limbs such that the nonwoven material is folded in zigzag form; and at least one welding device configured to weld a weld region of the first limb of a fold to at least one weld region of the second limb of a fold between the limbs of a fold in the folded state by means of a plastic welding process, wherein a welded joint is formed between the two facing sides of the limbs of a fold.

8. The apparatus according to claim 7, wherein the welding device comprises a heating element configured to be inserted between the limbs and to heat the weld regions, wherein the regions come into contact as the heating element exits and form a weld region.

9. The apparatus according to claim 7, wherein the welding device additionally comprises a counter-welding element, in particular a welding anvil, which is configured to be inserted between the limbs of an adjacent fold such that the heating element and the counter-welding element enclose the at least one weld region.

10. The apparatus according to claim 8, wherein the apparatus comprises a second welding device and is designed such that the heating elements of the two welding devices are inserted between the limbs from opposite sides of the nonwoven material.

11. The apparatus according to claim 7, further comprising: at least one embossing device configured to emboss at least one bulge in the first limb and/or at least one bulge in the second limb of a fold such that the bulges face one another.

12. The apparatus according to claim 7, wherein the at least one welding device is further configured to move the heating element in the direction of manufacture of the nonwoven material.

13. A zigzag-folded nonwoven material for a filter produced by means of a method according to claim 1 and having a plurality of folds which divide the nonwoven material into first limbs and second limbs, wherein a materially bonded welded joint connecting the first limb to the second limb is in each case arranged between a first limb and a second limb of a fold in at least one weld region, whereby weld regions which connect two limbs of a fold are only formed on facing sides of the limbs of the fold, wherein the surface at least in the weld region of facing sides of the limbs of a fold is changed by the welded joint and the surface of the side of the limbs of a fold opposite from the weld region is not changed by the welded joint.

14. The nonwoven material according to claim 13, wherein at least the sides of the limbs of the nonwoven material opposite the surface of the weld regions exhibit a structuring of in particular diamond-shaped and/or honeycombed form.

15. The nonwoven material according to claim 13, wherein a plurality of weld regions are formed between the limbs of a fold at least substantially perpendicular to the longitudinal direction (L) of the fold.

16. The nonwoven material according to claim 13, wherein the weld regions are arranged on at least one bulge in the first limb and/or on at least one bulge in the second limb of a fold, whereby the bulges face one another.

17. The nonwoven material according to claim 16, wherein the at least one bulge of the first limb and/or second limb of a fold is formed at least substantially perpendicular to the longitudinal direction (L) of the fold.

18. The nonwoven material according to claim 16, wherein a bulge of the first limb and a bulge of the second limb of a fold are arranged substantially opposite one another.

19. The nonwoven material according to claim 13, wherein the bulge of the first limb and/or the bulge of the second limb of a fold rises, in particular continuously or gradually, starting from the fold, whereby preferably the rise of the bulge of the first limb and/or the second limb is substantially lowest at the fold.

20. The nonwoven material according to claim 13, wherein the nonwoven material is formed from at least two layers.

21. The nonwoven material according to claim 13 having a plurality of layers, wherein a first layer comprises a different polymer or a different polymer mixture having a lower melting point on a surface of the nonwoven material to be welded than a second layer.

22. The nonwoven material according to claim 21, wherein the first layer exhibits a plateau for applying the weld, particularly of about 1 mm to 5 mm in thickness.

23. A filter having a nonwoven material according to claim 13.

Description

[0063] Further features, advantages and possible applications of the invention derive from the following description of exemplary embodiments in conjunction with the figures in which the same reference numerals are used for the same or corresponding elements of the invention. Shown therein at least partly schematically:

[0064] FIG. 1 an exemplary embodiment of a zigzag-folded nonwoven material for a filter in side view;

[0065] FIG. 2 a further exemplary embodiment of a zigzag-folded nonwoven material for a filter in side view;

[0066] FIG. 3 an exemplary embodiment of a zigzag-folded nonwoven material for a filter in top plan view;

[0067] FIG. 4 an exemplary embodiment of an apparatus for producing a zigzag-folded nonwoven material; and

[0068] FIG. 5 an exemplary embodiment of a method for producing a zigzag-folded nonwoven material.

[0069] FIG. 1 shows an exemplary embodiment of a zigzag-folded nonwoven material 1 for a filter in side view. The nonwoven material 1, which has preferably been produced by means of a so-called melt-spinning process such as a spun-bond process or a melt-blown process, exhibits a plurality of folds 2a, 2b, 2c which divide the nonwoven material 1 into first limbs 3a, 3b and second limbs 4a, 4b.

[0070] The folds 2a, 2b, 2c preferably run at least substantially parallel to each other. In order to obtain a zigzag-folded configuration of the nonwoven material 1, the folds 2a, 2b, 2c are thereby alternatingly folded in oppositely disposed folding edges. So doing thus achieves an accordion-shaped or zigzagged configuration of the nonwoven material 1.

[0071] A respective materially bonded connection is arranged in at least one weld region 5a, 5b between each first limb 3a, 3b and second limb 4a, 4b of a fold 2a, 2b, 2c. The weld regions 5a, 5b are thereby only formed between the limbs 3a, 3b, 4a, 4b of a fold 2a, 2b, 2c of facing sides of the limbs 3a, 3b, 4a, 4b of a fold 2a, 2b, 2c.

[0072] In particular, the surface of facing sides of the limbs 3a, 3b, 4a, 4b of a fold 2a, 2b, 2c is locally welded by the materially bonded connection, whereby the welding does not affect the regions on the respective far side from the weld region 5a, 5b.

[0073] As shown in this exemplary embodiment, bulges 8a, 9a are formed on the fold 2c or the weld region 5a respectively in the upper region. One respective bulge 8a is thereby formed in the first limb 3a and one respective bulge 9a in the second limb 4a of the fold 2c, wherein the bulges 8a, 9a are formed facing or in the direction of each other.

[0074] Preferably, the bulge 8a of the first limb 3a und and/or the bulge 9a of the second limb 4a of the fold 2c thereby rises starting from the fold 2c. Further preferably, this ensues continuously or gradually. In addition, the rise of the bulge 8a, 9a of the first limb 3a and/or the second limb 4a is substantially lowest/smallest at the fold 2c.

[0075] Further preferably, the bulges 8a, 9a can be designed as plateaus formed from a layer of the nonwoven material 1. Preferably, this layer can comprise a polymer or a polymer mixture having a lower melting point than other layers of the nonwoven material 1. Further preferably, such a layer can cover the entire surface of one or both sides of the nonwoven material.

[0076] FIG. 2 shows a further exemplary embodiment of a zigzag-folded nonwoven material 1 for a filter in side view. This exemplary embodiment differs in comparison to the exemplary embodiment of FIG. 1 in that bulges 8b, 9b are also arranged on the folds 2b, 2c arranged at the bottom in order to permanently connect the first limbs 3a, 3b and second limbs 4a, 4b of a fold 2b, 2c via welding.

[0077] Alternatively, the nonwoven material 1 can be designed such that a bulge 8a, 8b, 9a, 9b is only arranged on one of the two limbs 3a, 3b, 4a, 4b of a fold 2a, 2b, 2c. Doing so substantially reduces the manufacturing expenditure involved in producing the bulges 8a, 8b, 9a, 9b.

[0078] At least the surface of mutually facing sides of the limbs 3a, 3b, 4a, 4b of a fold 2a, 2b, 2c in the weld region 5a, 5b and at least the region of the surface of the side of the limbs 3a, 3b, 4a, 4b of a fold 2a, 2b, 2c opposite from the weld region 5a, 5b can thereby exhibit a different structure.

[0079] Furthermore, at least the side region of the limbs 3a, 3b, 4a, 4b of a fold 2a, 2b, 2c opposite from the weld region 5a, 5b comprises a grid. This is preferably of polygonal configuration. A diamond shape, and in particular a honeycomb configuration, to the grid has proven particularly suitable.

[0080] Particularly in order to form a first surface 6, which is preferably of grid-shaped design and different from the second surface 7 opposite from the first surface 6, the nonwoven material 1 comprises at least two layers. Particularly a first layer thereby forms the first surface 6 and a second layer forms the second surface 7 of the nonwoven material 1 opposite from the first surface 6.

[0081] Preferably, two adjacent folds 2a, 2b, 2c are distanced by at least approximately 10 mm, preferentially by at least approximately 14 mm, particularly preferentially by at least approximately 17 mm, and most preferentially by at least approximately 20 mm. Alternatively, the distance can also be larger, approximately 30 mm or more. Furthermore, the distances between two adjacent folds 2a, 2b, 2c can also be irregular to one another.

[0082] To produce a flat filter, the surfaces of the weld regions 5a on the one side of the nonwoven material 1 as well as the surfaces of the weld regions 5b on the other side of the nonwoven material 1 are preferably welded together. Depending on the individual application, however, forming only one weld region type, 5a or 5b, may also suffice with respect to the strength of such a filter. To produce a drum filter, in which the folded nonwoven material 1 is in an annular arrangement, generally only one type of welding region, 5a or 5b, is even ever formed.

[0083] FIG. 3 shows an exemplary embodiment of a zigzag-folded nonwoven material 1 for a filter in top plan view. The bulges 8a, 8b, 9a, 9b are formed such that the weld regions 5a, 5b, particularly the welded joints, are located in the region of the bulges 8a, 8b, 9a, 9b. This preferably reduces tensile and compressive loads on the welded joints since the first and second limb 3a, 3b, 4a, 4b of a fold 2a, 2b, 2c do not have to be additionally deformed to each other.

[0084] In this exemplary embodiment, the bulges 8a, 8b, 9a, 9b, the weld regions 5a, 5b or respectively folds 2a, 2b, 2c are formed in substantially uniform distribution. There can, however, also be an irregular distribution to the bulges 8a, 8b, 9a, 9b and/or weld regions 5a, 5b and/or folds 2a, 2b, 2c. In particular, an asymmetrical arrangement of the folds 2a, 2b, 2c relative to each other is also possible.

[0085] Illustratively, a first bulge 8a is formed below the depicted uppermost first fold 2a, same being substantially opposite from a bulge 9a above the depicted third fold 2c. The first bulge 8a is formed on a first limb 3a of the first fold 2a and the second bulge 9a is formed on a second limb 4a of the third fold 2c. A weld region 5a is thereby arranged at the contact area of the first bulge 8a and the second bulge 9a in which a welded joint materially bonds the first bulge 8a to the second bulge 9a.

[0086] A second fold 2b is arranged between the first fold 2a and the third fold 2c which is illustrated by a dashed line and folded or respectively creased in the opposite direction to the first fold 2a and the third fold 2c. Only a first side or respectively surface of the nonwoven material 1 is visible in this top plan view of the nonwoven material 1. It would thus in principle also be possible for a similar configuration of two adjacent folds 2a, 2b, 2c to be formed on the other side/surface of the nonwoven material 1 as is found between the first fold 2a and the third fold 2c.

[0087] A plurality of weld regions 5a, 5b of a defined length and at least substantially perpendicular to the longitudinal direction L of the folds 2a, 2b, 2c is preferably furthermore formed between the limbs 3a, 3b, 4a, 4b of a fold 2a, 2b, 2c, whereby such a configuration is not visible in this top plan view. Further preferably, the bulges 8a, 8b, 9a, 9b of the first limb 3a, 3b and/or of the second limb 4a, 4b of a fold 2a, 2b, 2c are likewise formed at a defined length and at least substantially perpendicular to the longitudinal direction L of the folds 2a, 2b, 2c.

[0088] The arrow H indicates a common direction of manufacture of a folded nonwoven material. The nonwoven material, which is generally stored as a rolled product, is folded substantially transverse to its two edges along a production line dictating the direction of manufacture H.

[0089] FIG. 4 shows an exemplary embodiment of an apparatus 10 for producing a zigzag-folded nonwoven material 1 for a filter.

[0090] This apparatus 10 as well as the block diagram according to FIG. 5 is used in explaining an exemplary embodiment of a method 100 for producing a zigzag-folded nonwoven material, wherein the limbs of the folds are fixed to one another by means of a materially bonded welded joint.

[0091] During the production method 100, the nonwoven material 1 successively passes through the individual stations of the apparatus 10 in the direction of manufacture H. The method 100 thereby comprises at least the successive working steps of folding 102 and welding/joining 103. Preferably, the method 100 also has a work step of embossing 101 the nonwoven material 1 prior to folding.

[0092] The apparatus 10 preferably comprises an embossing device 11 which is configured to emboss 101 at least one bulge 8a, 8b in a first limb 3a, 3b and/or at least one bulge 9a, 9b in a second limb 4a, 4b of a fold 2a, 2b, 2c, in particular prior to the folding, wherein the first limb 3a, 3b is faced toward the second limb 4a, 4b. In order to form one or more bulges 8a, 8b, 9a, 9b in the nonwoven material 1, the nonwoven material 1 is to that end preferably introduced into the embossing device 11 in flat state.

[0093] The nonwoven material 1 is folded in work step 102. To that end, the apparatus 10 comprises at least one folding device 12 configured to form a plurality of folds 2a, 2b, 2c in the nonwoven material 1, these running preferably substantially parallel to one another. The folds 2a, 2b, 2c thereby divide the nonwoven material 1 into first limbs 3a, 3b and second limbs 4a, 4b, whereby the nonwoven material 1 is folded so as to produce a zigzagged configuration of the nonwoven material 1.

[0094] In a final work step 103, at least one area of the first limb 3a, 3b is materially bonded to at least one area of the second limb 4a, 4b of a fold 2a, 2b, 2c by the formation of weld regions 5a, 5b. This ensues in the apparatus 10 by means of a welding device 13, wherein the welding device 13 is designed such that the weld regions 5a, 5b are only formed on facing sides of the limbs 3a, 3b, 4a, 4b of a fold 2a, 2b, 2c; i.e. there is substantially no structural change to the surface of the sides of the limbs 3a, 3b, 4a, 4b of a fold 2a, 2b, 2c faced away from one another resulting from the welding. Preferably, substantially all the weld regions are at least partially formed at or on the bulges. Preferably, the welding device 13 comprises a heating element 14 which enters between the limbs 3a, 4a; 3b, 4b for welding and heats the surfaces of the nonwoven material 1 in the weld regions 5a, 5b, whereby the weld regions 5a, 5b come into contact or are brought into contact as the heating element 14 exits and form at least one welded joint, in particular a weld seam. The heating element 14 serves to apply thermal energy in order to be able to plasticize the surfaces of the nonwoven material 1. Preferably, the heating element 14 is configured for thermal-contact welding, ultrasonic welding, infrared welding and/or laser welding. In the case of thermal-contact welding, the heating element can be designed as a heating rod or heating wire. In any case, however, the heating element 14 is designed so as to form spot or elongated joints between the limbs.

[0095] To join the weld regions 5a, 5b, the heating element 14 is preferably inserted between adjacent limbs 3a, 4a; 3b, 4b, or into the fold 2a, 2b, 2c they form respectively, and then extracted again, whereby the weld regions 5a, 5b in the folds can be heated. The direction of movement B of the heating element 14 is thereby oriented at least substantially perpendicular, preferably vertically, to the direction of manufacture H. Further preferably, the direction of movement B additionally comprises a component aligned at least substantially parallel to the direction of manufacture H. This can thereby comparatively increase the production speed; i.e. the speed at which the nonwoven material 1 moves in the direction of manufacture H, in the area of the welding device 13.

[0096] Additionally to be noted is that the exemplary embodiments are only examples which are not intended to limit the scope of protection, the applications and configuration in any way. Rather, the foregoing description is to provide the person skilled in the art with a guideline for implementing at least one exemplary embodiment, whereby various modifications can be made, particularly as regards the function and arrangement of the described components, without departing from the scope of protection resulting from the claims and equivalent combinations of features.

TABLE-US-00001 List of reference numerals 1 nonwoven material 2a, 2b, 2c fold 3a, 3b first limb 4a, 4b second limb 5a, 5b weld region 6 first surface 7 second surface 8a, 8b first bulge 9a, 9b second bulge 10 apparatus 11 embossing device 12 folding device 13 welding device 14 heating element L longitudinal direction of fold H direction of manufacture B direction of movement