Fabric And Method For Producing A Fabric

Abstract

A functional belt has a foam layer and at least one further functional layer. The foam layer and the further functional layer are joined to one another by laser transmission welding, in particular by NIR laser transmission welding. A method for producing a functional belt includes the following method steps: providing a compressible foam layer; providing a further functional layer bringing together the foam layer and the further functional layer and joining the compressible foam layer to the further functional layer by laser transmission welding, in particular by means of NIR laser transmission welding. A technical textile, in particular a fabric for use in a machine for the production or processing of a fibrous material web, preferably press felt of a paper machine, a sealing band or a textile-reinforced insulation material, includes, or is made of, such a functional belt.

Claims

1-15. (canceled)

16. A functional belt having a direction in length and a direction in width, the functional belt comprising: a foam layer and at least one functional layer joined to said foam layer by laser transmission welding.

17. The functional belt according to claim 16, wherein said foam layer and said at least one functional layer are interconnected by near infrared laser transmission welding.

18. The functional belt according to claim 16, wherein said foam layer comprises or consists of a polymer foam.

19. The functional belt according to claim 18, wherein said polymer foam comprises an elastomer.

20. The functional belt according to claim 18, wherein said polymer foam comprises a polyurethane.

21. The functional belt according to claim 16, wherein said foam layer comprises one or both of an open-cell polymer foam or a closed-cell polymer foam.

22. The functional belt according to claim 16, wherein said at least one functional layer consists of or comprises a material selected from the group consisting of a woven fabric, a warp/weft-knitted fabric, a cross-laid scrim, a non-woven fabric, a film, a foil, and a polymer foam.

23. The functional belt according to claim 16, wherein either said foam layer or said at least one functional layer is a layer that is largely transparent to light in a range of a laser wavelength, while the respective other said layer has at least a surface with an absorbent layer that is largely absorbent to light in the range of the laser wavelength.

24. The functional belt according to claim 23, wherein the absorbent layer comprises an absorber which absorbs light in the range of the laser wavelength.

25. The functional belt according to claim 24, wherein said absorber is selected form the group consisting of a dye, an ink, and carbon black.

26. The functional belt according to claim 24, wherein said absorber is incorporated in a volume of the absorbent layer, or said absorber is applied to at least one surface of the absorbent layer.

27. The functional belt according to claim 16, wherein the functional belt is embodied as roll goods, as an endless loop, or a belt with a closable seam.

28. The functional belt according to claim 16, wherein said foam layer is composed of, or comprises, a plurality of individual foam elements disposed in one or both of the direction of length or the direction of width in a mutually abutting relationship.

29. A method for producing a functional belt, the method comprising the following process steps: i. providing a compressible foam layer; ii. providing a further functional layer; iii. converging the foam layer and the further functional layer; and iv. connecting the compressible foam layer to the further functional layer by laser transmission welding.

30. The method according to claim 29, wherein the connecting step comprises near-infrared laser transmission welding.

31. The method according to claim 29, which comprises placing the foam layer and the functional layer on top of one another and welding the layers under a joining pressure.

32. The method according to claim 29, which further comprises at least one further process step, to be performed prior to and/or after welding, of at least partially compacting the foam layer under the influence of elevated pressure and elevated temperature.

33. The method according to claim 32, which comprises cooling the foam layer under pressure after the compacting step.

34. A technical textile, comprising a functional belt according to claim 16 configured for use in a machine for producing or processing a fibrous web.

35. The technical textile according to claim 34, configured as a fabric clothing in a paper-making machine, as a press felt of a paper machine, as a sealing belt, as a textile-armored insulation material, or as a component part of such a technical textile.

Description

[0051] The invention will be described in more detail hereunder by way of example by means of schematic figures which are not to scale.

[0052] FIG. 1 shows a fragment of an embodiment of the method according to the invention.

[0053] FIG. 2 shows a fragment of a further embodiment of the method according to the invention.

[0054] FIG. 2b schematically shows the tailoring of a foam layer at an abutment point.

[0055] FIGS. 3a and 3b show two embodiments of the use of a functional belt according to the invention as a press felt.

[0056] FIG. 1 shows a foam layer 2 and a further functional layer 1. The further functional layer 1 can be a woven fabric, for example. This woven fabric in the functional belt later provides inter alia the desired dimensional stability and tensile strength. This woven fabric in one advantageous embodiment is composed of a woven multifilament fabric or of a woven monofilament fabric.

[0057] The filaments herein can be composed of a multiplicity of polymers. The further functional layer 1 in one advantageous embodiment is composed of a woven monofilament fabric from polyamide 6 having yarn diameters of 0.3 mm to 0.5 mm, preferably of 0.4 mm. An open-cell polyurethane foam can be used as the foam layer 2. In the embodiment shown in FIG. 1, the further functional layer 1 is transparent to the light of the laser 4. By contrast, the foam layer 2 is absorbent in the range of the laser wavelength. This is often evident in the coloration of the foam layer. Foam layers 2 of this type are thus usually anthracite, black, or grey in color. The foam layer 2 has optionally already been compacted in a further process step. Should the functional belt be provided for employment in a press felt for a paper machine, the foam belt 2 when provided often has a thickness in the range of 3 mm to 15 mm.

[0058] The foam layer 2 and the further functional layer 1 are converged and conjointly guided over a roller 3. Contact pressure onto the roller 3 results from applying a web tension and by wrapping of the roller 3, on account of which the desired joining pressure is created. The joining pressure in many applications is between 1 N/cm.sup.2 and 5 N/cm.sup.2. A laser 4 is attached above the roller 3. Said laser in an advantageous embodiment emits light in the NIR range. The usual output of such laser 4 is in the range of 100 W to 600 W (linear). In principle, however, lasers which illuminate an area can also be provided. The laser 4 in FIG. 1 has a linear width of 30 mm. The light penetrates the further functional layer 1 up to the interface to the foam layer 2. Said light there is absorbed by the foam layer, on account of which heating and welding of the two layers takes place. However, the use of planar laser fields which can be generated by respective optics is also conceivable.

[0059] In the embodiment of FIG. 1, the foam layer 2 and the further functional layer 1 are guided past below the laser light. The speeds used therein are relatively minor, in the range between 20 mm/s and 100 mm/s, but can also be higher or lower, depending on the material and the laser. A functional belt 7 having a width of 30 mm is created after welding. Wider belts can be produced in that a plurality of lasers which are disposed beside one another, or lasers having wide lines are used, for example. Moreover, the foam layer 2 and the further functional layer can be run under the laser 2 multiple times in an offset manner.

[0060] FIG. 2 shows an embodiment of the method according to the invention in which the laser 4 is positioned above the further functional layer 1 and the foam layer 2. In the embodiment illustrated, an endless further functional layer 1 is set up on two rollers 3. The tensile stress herein is usually less than 2 kN/m, especially less than 1 kN/m. A foam layer 2, especially an open-cell soft polyurethane foam, is incorporated between the further functional layer 1 and a fixed element 6. The foam layer is usually embodied so as to be absorbent to NIR light. When viewed, such foam layers 2 often appear to be dark, for example of anthracite color. The thickness of the foam layer 2 is preferably in the range of 3 mm and 15 mm. The required joining pressure in this embodiment is generated in that a fixed element 6, preferably a polyamide sheet, is attached below the foam layer. The joining pressure by means of optics 5, especially roller optics 5 which are attached to the laser 4 is generated on the layers 1, 2 lying below said optics 5. The joining pressures generated in such a manner, in the context of roller optics having a width of 30 mm, in preferred embodiments are between 2 N and 10 N, wherein pressures of 40 N are also possible, however. In particularly preferred embodiments, the joining pressures are between 10 N and 20 N, but in individual cases can also be thereabove or therebelow, for example between 4 N and 6 N. Should other optics be used, for example wider roller optics, these pressure values can be adapted in a corresponding manner. The output that is generated by the laser 4 in preferred embodiments is between 100 W and 500 W, but can also be up to 600 W or more. The laser output is particularly preferably between 200 W and 300 W. However, a higher or lower laser output can also be provided in special applications. These output figures are again related to roller optics having a width of 30 mm, and can be adapted in a corresponding manner when other optics are used. In the case of roller optics having a width of 60 mm, double these output values can be applied, for example.

[0061] In the case of the embodiment shown in FIG. 2, means by means of which the laser 4 can be moved transversely to the running direction of the layers are provided. The laser 4 can thus be fastened so as to be movable on a traversing unit. The laser 4 is usually moved at a speed of less than 200 mm/s, preferably less than 100 mm/s, particularly preferably at 40 mm/s to 60 mm/s. The further functional layer 1 and the foam layer 2 can rest or else move along the web running direction of said layers during this movement of the laser. The further functional layer 1 by way of the movement of the laser 4 is welded to the further functional layer in a strip having the width of the optics 5. In the case in which the further functional layer 1 and the foam layer 2 are resting, a welded strip which is oriented transversely to the running direction of the layers is thus created. When usual optics are used, the strips thus generated are between 20 mm and 100 mm, especially between 25 mm and 40 mm, wide. After welding, the belt 7 from the further functional layer that is welded to the foam layer 2 is moved forward in the running direction of the belt by the width of the welded strip. The process of welding can thereafter be continued as has been described above. The laser 4 in the case of the subsequent welding procedure is expediently moved across the layer in the opposite direction. The entire functional belt can be welded in this way, if desirable.

[0062] As is shown in FIG. 2b, the foam layer 2 prior to final welding, that is to say prior to final traversing of the laser 4, at the abutment points can be tailored such by means of a cutting device 9 that a clean abutment is created. The region B of the abutment point has not yet been welded here, while the other regions A have already been welded as has been described above. The non-welded region B herein can have the width of the optics 5 of the laser 4, or else be narrower or wider.

[0063] FIG. 3a shows a potential example of the the use of a functional belt 7 according to the invention as a technical textile, especially as a press felt 7 for a paper machine. The felt 7 comprises a plurality of further functional layers 1a, 1b, 1c, specifically a carrier structure 1a and non-woven layers 1b, 1c that are needled to both sides. The carrier structure 1a can for example be composed of a woven fabric, a warp/weft-knitted fabric, a cross-laid scrim, or can comprise the latter.

[0064] A foam layer 2, in particular an elastic open-cell foam layer 2, is furthermore provided on the paper side in FIG. 3a, said foam layer 2 according to the invention being connected to the non-woven layer 1b on the paper side by laser transmission welding. To this end, the foam is advantageously embodied as a layer that at least on the surface thereof is largely absorbent to light in the range of the laser wavelength. During production, the laser light under the joining pressure can be directed from the direction of the running side through the felt structure, for example. In this case, the carrier structure 1a and the non-woven layer or non-woven layers 1b, 1c, respectively, can be embodied so as to be largely transparent to light in the range of the laser wavelength.

[0065] Such a press felt 7 on the paper-contacting surface thereof has a foam layer 2. In general, felts 7 having such a foam layer 2 as a paper-contacting surface can be advantageous since said surface has a minor tendency toward marking since, by contrast to paper-contacting non-woven layers, no non-woven fibers can be pressed into the paper surface. Moreover, despite the comparatively smooth surface of the foam layers, high rates of permeability can be achieved when using respective foams. This can be highly advantageous for dewatering the paper web.

[0066] In order for the foam layer 2 to be compacted and solidified, it can be provided that a press felt such as the one that has been described above, in particular, after welding of the foam layer 2 to the paper-side non-woven layer 1b, is guided over a hot roller. Such a roller is preferably operated at temperatures between 100° C. and 250° C., particularly preferably between 160° C. and 210° C. The surface of the foam layer 2 is also smoothed by this treatment.

[0067] Open-cell soft polyurethane foams or filter foams, respectively, having a porosity of 30-60 PPI, for example, and a thickness of 2 to 12 mm, in particular 3-8 mm, can preferably be used as a foam for a felt of this type or else for other functional belts according to the invention. This thickness can optionally be further reduced by a compacting process such that the foam layer in the finished product has a lesser thickness.

[0068] FIG. 3b shows a further advantageous use of the one functional belt 7 having a plurality of further functional layers 1a, 1b, 1c, 1d as a press felt 7. A carrier structure 2 is provided herein, one or a plurality of non-woven layers 1b being attached to the surface on the paper side of said carrier structure preferably by needling. In turn, a foam layer 2 can be fastened to the surface of the topmost non-woven layer 1b by transmission welding. The foam layer 2 herein is preferably embodied so as to be largely absorbent to light in the range of the laser wavelength. A non-woven layer 1d as a further functional layer which in this instance provides the paper-contacting upper side of the felt 7 is provided on the paper-side surface of the foam layer 2 in FIG. 3b. This non-woven layer 1d can either be fastened in a conventional manner by needling. However, in particularly advantageous embodiments, this paper-contacting non-woven layer 1d can again be fastened to the foam layer 2 by means of laser transmission welding. Non-woven layers 1b, 1d are thus fastened by means of welding to both sides of the foam layer 2 in this embodiment. This is possible when the further functional layers 1a, 1b, 1c, 1d are embodied so as to be largely transparent to light in the range of the laser wavelength, while the foam layer 2 is embodied so as to be absorbent in this range.

[0069] The foam layer 2 can again be compacted and solidified by heat and pressure also in the case of this embodiment, wherein this compacting can take place prior to and/or after the first and/or second welding.

[0070] The functional belt in FIG. 3b on that side of the carrier structure la that faces away from the paper has a further non-woven layer 1c. Depending on the specific application, this non-woven layer 1c can also be dispensed with. Alternatively, however, even further non-woven layer can be provided.

LIST OF REFERENCE SIGNS

[0071] 1, 1a, 1b, 1c, 1d Further functional layer

[0072] 2 Foam layer

[0073] 3 Roller

[0074] 4 Laser

[0075] 5 Optics

[0076] 6 Fixed element

[0077] 7 Functional belt

[0078] 9 Cut

[0079] A Welded region

[0080] B Non-welded region