fabric

Abstract

A seam felt for use in the press section of a machine for producing fabrics, in particular fibrous webs, comprising a fabric (1) having at least one base structure and at least one laminated fibrous layer arranged on the base structure, the at least one laminated fibrous layer being arranged on the side facing the fibrous web and / or on the side facing the machine, the fabric having at least one seam zone in which seam loops are connected to one another by at least one insert wire to make the fabric endless, the at least one laminated fibrous layer being divided in the region of the seam zone by at least one incision forming seam flaps and seam wedges, at least one connecting element (20) inserted between the seam flap and the seam wedge, the at least one connecting element being material-bonded, in particular welded, to the laminated fibers of the seam flap and / or seam wedge, and a method for using this type of fabric.

Description

[Technical field]

[0001] The invention relates to a seam felt for use in the press section of a machine for producing fabrics, in particular textile webs, according to the preamble of claim 1 and to a seam felt for use in the press section of a machine for producing fabrics, in particular textile webs, according to claim 2. 7 and a method for using such a fabric as described in the preamble of the present invention.

[0002] With regard to fabrics for paper machines, in particular press felts, the development has already shifted from endless fabrics to seamed fabrics. The advantage for the user is that the seamed fabrics can be easily installed on the machine. Furthermore, since it is not necessary to take measures for the slipping on of endless fabrics in new installations, considerable construction effort can be saved.

[0003] In particular, seam felts are produced by means of a plug-in wire seam which joins the felt ends in the region of the backing. A nonwoven layer is applied to the endless backing at least on the paper side (often also on the running side) and needled. Since this is advantageous from a production engineering perspective, the nonwoven layer is also needled on the plug-in wire seam.

[0004] To pull the felt into the paper machine, the seams of the felt must be reopened, which is possible without problems in the base fabric by removing the insert wires, but the nonwoven layer that has been needled across the seam must be unwound.

[0005] For this purpose, the paper-side nonwoven layer of one felt end is separated from the paper-side nonwoven layer of the other felt end in the region of the plug wire by an incision, which is made into the still-closed nonwoven after needling across the seam. This incision can be made vertically, but is preferably made slightly obliquely, i.e. preferably at an offset of 5-30° from the vertical.

[0006] After the felt is pulled in, the plug wire seam is closed again, for example by a plug wire in the form of a fiber bundle. The nonwoven layers of the two felt ends are in contact with each other or overlap, but the properties of the felt in this seam area, for example the porosity, differ from the properties of the rest of the felt.

[0007] To overcome this drawback, several possibilities for optimizing the seam area are known from the prior art. For example, WO 02 / 35000 proposes to introduce strips of flow-blocking material into the seam area of ​​the fabric. Alternatively, EP 1 918 453 as well as WO 2015 / 024718 describe the introduction of liquid materials or small particles into the seam area.

[0008] All these optimizations of the seam area work to modify the flow characteristics in this area, but do not overcome the fundamental drawback that the nonwoven support is permanently weakened at this point by the cut.

[0009] Thus, for example, with cuts, especially with inclined cuts, the fiber fixation in the seam area is smaller than in the remaining area of ​​the felt surface. Due to the geometry of the felt seam, which is generally unfavorable for fiber fixation based on seam loops, and due to the fact that the seam loops must be kept sufficiently free of fiber material so that the plug wire can be pushed in, improvements in the fiber fixation are possible, but these possibilities are limited.

[0010] Furthermore, the incision is easily damaged, since no fiber fixation occurs directly in the incision area to the fibers on the other side of the nonwoven support. Experience has shown that the felt also wears more strongly in the seam area, and damaged seam areas are often the cause for marks in the paper or for paper breakage during paper production. This incision therefore causes a shortening of the felt's service life, even though the felt is still good enough outside the seam and can still be used for several days.

[0011] Furthermore, when the felt is stretched, the gaps on the seams may widen and thus be exposed to increased action by contact elements or water jet nozzles which cause wear in the paper machine.

[0012] SUMMARY OF THE PRESENT EMBODIMENT An object of the present invention is to overcome the problems of the prior art.

[0013] In particular, it is an object of the present invention to propose a fabric which is more wear-resistant than known fabrics.

[0014] Another object of the invention is to propose a fabric whose seams have a reduced tendency to mark compared to known seam fabrics.

[0015] In particular, it would be desirable to be offered the possibility of obtaining the advantageous effects without or with only a small change in the permeability of the seam area.

[0016] Additionally, it would be desirable to have a method for using such a fabric proposed.

[0017] These problems are solved by the fabric according to claim 1 and the 7 The problem is solved completely by the method for using the fabric, which is described in

[0018] Further advantageous features of the arrangement according to the invention are set forth in the dependent claims.

[0019] With regard to the fabric, this problem is solved by a fabric, in particular a seam felt for use in the press section of a machine for producing a fiber web, which has at least one base structure and at least one laminated fiber layer arranged on the base structure, the at least one laminated fiber layer being arranged on the side facing the fiber web and / or on the side facing the machine, the fabric having at least one seam zone, in which the seam loops are connected to one another by at least one insert wire to make the fabric endless, and the at least one laminated fiber layer is divided in the region of the seam zone by at least one cut, forming a seam flap and a seam wedge. According to the invention, at least one connecting element is inserted between the seam flap and the seam wedge, which is connected in a material-bonding manner, in particular welded, to the laminated fibers of the seam flap and / or the seam wedge.

[0020] Press felts usually have at least one laminated fiber layer on the side facing the fiber web and may additionally have a laminated fiber layer on the running side facing the machine.

[0021] The terms "seam flap" and "seam wedge" are taken from the common usage when using angled cuts. In the case of fabrics with vertical cuts, which are also expressly included by this invention, these two terms refer to one or the other cut end of the nonwoven layer, respectively.

[0022] In one particularly preferred configuration, the bonding of the at least one connecting element with the laminated fibres of the seam flap and / or seam wedge can be carried out by NIR transfusion welding. For this, it is of course highly advantageous if the at least one connecting element comprises or consists of a polymer material that at least largely absorbs light having a wavelength in the NIR range of 780 nm to 3 μm, preferably 780 nm to 1300 nm. It is understood that the polymer material does not necessarily have to be absorbent over the entire NIR range between 780 nm and 1300 nm (or 3000 nm). It is entirely sufficient if the polymer material is at least largely absorbent in one or more subranges of this NIR range. Light having a wavelength in this subrange can be used for the welding.

[0023] The laminating fibers of the nonwoven layers are most often made of polyamide, which is sufficiently transparent to light in this wavelength range.

[0024] Thus, the seam zone with at least one bonding element can be irradiated with light of the corresponding wavelength under a constant bonding pressure. A laser or another suitable source can be used as the light source. The bonding element absorbs the light, heats up and melts completely or partially, whereby a material-bonding bond is formed between the bonding element and the laminated fibers in contact with it. The laminated fibers are heated essentially only via contact with the bonding element. As a result, the laminated fibers of the nonwoven layer are largely unchanged by the bonding process. Thus, the bonding process does not cause any significant changes in the permeability or porosity of the seam area.

[0025] This advantageous property occurs automatically during transmission welding, whereas during equally possible bonding, for example by adhesive or ultrasonic welding, the joining process must be controlled very precisely.

[0026] The absorbing properties of the bonding element can be realized, for example, by adding an absorbing additive to the bonding element. Soot (carbon black), for example, is suitable for this purpose. However, absorbers with other colors or transparent absorbers are also available on the market, for example from the company Clearweld (www.clearweld.com).

[0027] The additives may be added to the polymeric material or used as a coating on the bonding elements.

[0028] The absorbing additive makes it possible to produce the connection elements from the same polymer material as the laminated fibers of the nonwoven layers, which is mostly polyamide, and yet use the advantageous technique of NIR transwelding. Due to the uniformity of the material, a particularly good and durable welded bond results.

[0029] It is particularly advantageous if after joining, i.e. especially after welding, at least one connecting element is connected in a material-bonding manner to the laminated fibres of the seam flap and the seam wedge, which results in a firm connection of the two cut edges to one another, which improves the fibre fastening and makes the seam more abrasion-resistant. In addition, this prevents the nonwoven layers from stretching under tensile loads and reduces the tendency of the seam to mark.

[0030] In the applicant's attempts to improve the seam, it has surprisingly been found that the use of connecting elements allows for significantly improved results to be obtained than would be possible by simple bonding, such as, for example, welding both cutting edges to one another.

[0031] This is to be understood in that, if no connecting element is provided, contact points and thus bonding sites only occur between the two cutting edges if the laminate fibers of one edge happen to come into contact with the laminate fibers of the other edge, so that the joint that can be achieved in this way is usually only very weak.

[0032] The joining elements inserted in the seams act as bridges between the contact points of both edges in the fabric proposed herein, each of which has multiple contact points with the joining elements, which significantly increases the probability of a solid joint being created compared to when no joining elements are used.

[0033] As will be explained in more detail below, the user has a relatively large degree of freedom when selecting the joining element, or possibly multiple joining elements, in a seam: it is possible to select joining elements such that they have little effect on the permeability of the seam, yet still produce a robust bond.

[0034] On the other hand, if it is desired to influence exactly such properties of the seam, this is possible by the selection of further connecting elements.

[0035] Fabrics according to various aspects of the present concept also allow the user great flexibility in designing seam areas.

[0036] The method for using the fabric according to the invention consists first of drawing the fabric into the press section of a machine for producing a fiber web and then making the fabric endless by closing the interleaved wire seam. In the case of known seam fabrics, this is where the process ends. In the case of the fabric proposed here, it is then possible to connect, in particular weld, at least one connecting element to the laminated fibers of the seam flap and / or seam wedge.

[0037] Such a method can be implemented in many different variations.

[0038] In one variation, at least one connecting element is inserted between the seam flap and the seam wedge only after the fabric has been drawn into the machine, in particular after it has been made endless by means of an insert wire, and then connected in a material-bonding manner.

[0039] In another variant, at least one fastening element may be provisionally connected to the seam wedge or seam flap before the fabric is drawn into the machine. "Provisional" in this variant means that in this configuration the fastening element has a connection with the seam flap or seam wedge before the drawing. However, this connection is not yet a material-bonding type connection afterwards. Such a provisional connection may be, for example, a form-locking connection (for example light needling or spot stitching) or an adhesive connection, in particular with a water-soluble adhesive, which can be washed again during a later operation of the machine. This has the advantage that the fastening element is positioned in the correct position, since the operator who draws in the fabric usually does not have the necessary knowledge and technical competence for this.

[0040] Alternatively, in another variant, at least one connecting element can already be connected to the seam wedge or seam flap in a material-bonded manner before pulling into the machine. The advantage here is that this permanent connection can almost completely eliminate slippage of the connecting element during pulling. On the other hand, this method requires two joining steps, for example a welding step, which can be a disadvantage. Depending on the application, the advantages or disadvantages can outweigh each other.

[0041] In one advantageous configuration it may be provided that at least one connecting element is configured as a thread-like or strip-like connecting element.

[0042] A joining element having a similar thickness and width, but a significantly greater longitudinal extension, is said to be thread-like.

[0043] In a thread-like configuration, the connecting element may in particular be configured as a monofilament, a multifilament bundle or a twisted thread.

[0044] A connecting element whose width is significantly greater than its thickness and whose longitudinal extension is significantly greater than its width is said to be strip-like.

[0045] In a strip-like configuration, the at least one connecting element may in particular be configured as a textile strip, a nonwoven, a film or a foam.

[0046] The textile strips may for example be woven, knitted or woven, and the nonwovens may for example be so-called melt-sprayed or melt-blown nonwovens.

[0047] Advantageously, the thread- or strip-like connecting elements may have a length in the longitudinal direction of at least 10 mm, in particular at least 20 mm. A larger length of the connecting elements improves the above-mentioned bridging effect of the connecting elements.

[0048] Generally, it is generally advantageous if the one or more joining elements are distributed over the entire length (in CD) of the incision.

[0049] This is achieved on the one hand in that the connecting element or elements extend over a large portion of the length of the cut.

[0050] If multiple connecting elements are used, all of these connecting elements may be identical, alternatively it is also conceivable that connecting elements of different types are inserted into the cutouts.

[0051] In particular, it may be provided that the thread-like or strip-like joining elements extend over at least half the width, preferably the entire width, of the fabric in the cross machine direction. In order to avoid confusion, it should be clarified once again that the longitudinal or length direction of the joining elements in this case extends in this case substantially along the cut, i.e. in the cross direction (CD) of the fabric.

[0052] Modern fabrics may have widths of 10 m or more, in which case the length of the thread-like or strip-like connecting elements is significantly greater than the abovementioned 10 mm or 20 mm. The length of the connecting elements is in the range of several meters (for example, 2 meters or even more than 5 meters).

[0053] Alternatively or additionally, a number of connecting elements may be provided which are configured, for example, in the form of laminated fibres and are introduced into the incisions.

[0054] Advantageously, the fibres may be configured such that they at least largely absorb light having wavelengths in the NIR (near infrared) range of 780 nm to 3 μm.

[0055] Particularly preferably, these fibers may be configured to at least largely absorb light having wavelengths in the NIR range of 780 nm to 1300 μm, since above 1300 nm there is an increased risk that the laminated fiber or the material of the basic structure will absorb this light to some extent, which may be undesirable.

[0056] Further advantageous embodiments of the invention will now be described, by way of example only, with reference to the drawings, in which the features mentioned can not only be advantageously implemented in the combinations presented, but can also be combined with one another individually. [Brief description of the drawings]

[0057] [Figure 1] FIG. 1 illustrates a portion of a fabric according to one embodiment of the present invention. [Diagram 2] FIG. 13 shows a portion of a fabric according to another embodiment of the present invention. [Diagram 3] FIG. 13 shows a portion of a fabric according to another embodiment of the present invention. [Figure 4] FIG. 13 shows a portion of a fabric according to another embodiment of the present invention.

[0058] The drawings are explained in detail below.

[0059] FIG. 1 shows a part of a fabric 1 according to one embodiment of the invention. In particular, a seam zone 2 is also shown in FIG. 1. The fabric comprises a base structure 3, which is configured as a backing 3. Each end of the base structure has one seam loop 4 in each case. Such seam loop 4 may be formed, for example, by folding and overlapping the base structure 3. The seam loop 4 is formed by warp threads (MD yarns) 6 of the backing 3. In addition, separate weft threads (CD yarns) of the backing may be removed to form the seam loop 4. The fabric 1 is made endless by both seam loops 4 being interlocked with one another and connected by the introduction of an insert wire 5. The insert wire 5 may be a separate filament. The fabric 1 shown in FIG. 1 shows, as an alternative, one insert wire 5 formed from a number of filaments. The skilled person is usually completely free to choose a suitable insert wire 5. The advantages of the invention can be achieved regardless of the choice of the insert wire 5.

[0060] The fabric 1 further comprises two laminated fibre layers 8, 8b. The laminated fibre layer 8b on the running side can possibly be omitted. The laminated fibre layer 8 on the paper side is consistently applied onto the base structure 3, in particular by needling. In order to be able to open the fabric 1 for pulling into the machine, the laminated fibre layer 8 is opened by an incision 9 across the seam. This incision 9 can in principle also be made vertically. However, as shown in FIG. 1, the incision 9 can also usually be made obliquely, i.e. at an angle to the vertical. This angle is preferably between 5° and 30°. This results in the formation of a seam flap 10 and a seam wedge 11. In this case, the seam flap 10 overlaps the seam wedge 11 in the closed fabric 1.

[0061] In cross section, the arrangement shown in Fig. 1 has three exemplarily inserted connecting elements 20, which are each configured as threads extending across the entire transverse direction of the fabric 1 or the incision 9. As threads 20, for example, monofilaments, multifilament bundles or twisted threads can be used. Also, more or less than the three threads 20 shown can be used.

[0062] The connecting elements 20 may be evenly distributed over the height of the incision 9. Alternatively, a non-uniform distribution may also be advantageous, e.g. more connecting elements 20 being arranged near the base structure 3 than towards the paper side, or vice versa.

[0063] If several connecting elements 20 are used, all these connecting elements 20 may be identical. Alternatively, it is also conceivable to insert connecting elements 20 of different types into the incisions 9.

[0064] These threads 20 are material-bonded to the seam flap 10 and to the seam wedge 11. This material-bonded bond can be, for example, a welded bond. It is therefore highly advantageous if the connecting elements 20, in this case the threads 20, are made of a polymer that at least largely absorbs light in the relevant NIR wavelength range of 780 [nm] to 1300 [nm]. For example, the material from which the press felt in the seam area is made (usually PA6 or PA66) is sufficiently transparent in this wavelength range. A welded bond can therefore be produced very simply by NIR-transmitting welding. It is particularly highly advantageous if the same polymer (for example PA6 or PA66) is used for the connecting elements 20 as the laying fibers 8, which polymer has advantageous absorption properties due primarily to the added absorbing additives. Due to such a material match between the connecting elements 20 and the laying fibers 8, a particularly durable welded bond is achieved. Alternatively, however, any suitable thermoplastic resin having good compatibility with the material of the laminated fibre layers 8, 8b can be used for the connecting element 20, such as copolyamide, PEBA or thermoplastic polyurethane.

[0065] As shown in Fig. 1, the laminated fibre layer 8b on the running side has a larger gap in the seam area 2. This facilitates, for example, the introduction of the insert wire 5 and may only have a minimal effect on the quality of the paper produced. However, within the scope of the invention, it is also possible to treat the laminated fibre layer 8b on this side in the same way as the paper side, i.e. also on the running side the laminated fibre layer 8b may be joined by the insertion of a joining element 20 across the seam.

[0066] The fabric 1 shown in FIG. 2 differs from the configuration shown in FIG. 1 solely by the choice of the connecting element 20. In FIG. 2, a single strip-shaped connecting element 20 is provided. The strip-shaped connecting element 20 may be, for example, a nonwoven, foam, film or woven strip and may in particular also extend over the entire width of the felt 1 or of the incision 9. In the case of a strip-shaped connecting element 20, in particular a film 20, it is appropriate to choose a very thin film which does not affect or only affects very little the permeability of the seam zone 20. The film can be cut, for example, so that its length corresponds to the width of the felt and its width corresponds to the height of the incision 9. This improves the nonwoven fixation by the film, while the dewatering in the depth direction of the felt 1 is hardly affected by the small film thickness. Preferably, a film or foil with a thickness of up to 50 μm can be chosen. In particular, permeable or perforated films are advantageous. The film or foil may be unoriented or uniaxially or biaxially oriented.

[0067] It may also be provided that the film or foil is fully or fully inserted into the incision 9 and that the permeability of this film only occurs when the welding process dissolves (for example by melting) the closed film structure.

[0068] FIG. 3 shows a fabric 1 in which the connecting element 20 is realized by flocking of the seam wedge 11. Alternatively or additionally, flocking of the seam flap 10 can also be performed. The flocking fibers 20 are preferably designed to be absorbent in the NIR wavelength range. The flocking brings about a connection between the connecting element and the seam wedge 11. However, this connection is usually only temporary. When the incisions 9, which are shown still open in FIG. 3, are closed, possibly with a joining pressure, a material-bonding connection with the seam wedge 11 and / or the seam flap 10 can be realized by a welding process, preferably by transmission welding.

[0069] FIG. 4 finally shows a configuration in which laminate fibers absorbent in the NIR wavelength range are deliberately introduced as bonding elements 20 into the laminate fiber layer 8 in the region of the incisions 9. The material-bonding type of bonding can also be achieved by welding. The absorbent laminate fibers can also be introduced already during the production of the nonwoven layer 8. Alternatively, the laminate fibers can also be added later, i.e. after the formation of the incisions 9, to the seam wedge 11 and / or the seam flap 10. Advantageously, these absorbent laminate fibers can be distributed in the seam flap 10 and / or the seam wedge 11 over the entire width of the fabric 1 and in the longitudinal direction of the fabric 1 in the range of 1 mm to 20 mm, in particular 2 mm to 10 mm. The absorbent fibers can also be provided in a larger range of the laminate fiber layer 8, 8b. In particular, it can be provided that the absorbent fibers are distributed over the entire laminate fiber layer 8, in particular on the paper side.

[0070] The drawings shown suggest various possibilities of the invention, but the invention is not limited to these embodiments. [Explanation of symbols]

[0071] 1. Fabric 2. Seam Zone 3 Basic structure 4. Seam Loop 5 Plug-in Wires 6 Longitudinal (MD) yarns 7 Cross-machine direction (CD) yarns 8,8b Laminated fiber layer 9 Cutting 10 Seam flap 11 Seam Wedge 20 Connecting Elements

Claims

1. A fabric (1), in particular a seam felt for use in the press section of a machine for producing a fibrous web, said fabric (1) having at least one base structure (3) and at least one laminated fibrous layer (8) arranged on said base structure (3), said at least one laminated fibrous layer (8) being arranged on the side facing the fibrous web and / or on the side facing the machine, said fabric (1) having at least one seam zone (2) in which seam loops (4) are connected to one another by at least one insert wire (5) in order to make said fabric (1) endless, said at least one laminated fibrous layer (8) being divided in the region of said seam zone (2) by at least one incision (9) forming seam flaps (10) and seam wedges (11), At least one connecting element (20) is inserted between the seam flap (10) and the seam wedge (11), the at least one connecting element (20) being fused to the laminated fabric of the seam flap (10) and / or the seam wedge (11); and the at least one coupling element comprises a polymer material that at least largely absorbs light having a wavelength in the NIR range of 780 nm to 3 μm, in particular 780 nm to 1300 nm, The laminated fiber layer (8) comprises polyamide, A fabric (1), characterized in that the unitizing elements (20) are loaded with an absorbent additive.

2. The fabric of claim 1 , wherein the at least one uniting element is configured as a thread-like or strip-like uniting element.

3. 3. The fabric according to claim 2, wherein the thread- or strip-like connecting elements have a length in the longitudinal direction of at least 10 mm, in particular at least 20 mm, preferably more than 2 m.

4. 4. The fabric according to claim 1, wherein a number of connecting elements are inserted between the seam flap (10) and the seam wedge (11), said connecting elements being material-bonded to the laminated fabric of the seam flap (10) and / or the seam wedge (11), in particular being welded to said laminated fabric.

5. 5. The fabric according to claim 1, wherein the at least one connecting element is configured as a thread, in particular as a monofilament, multifilament bundle or twisted yarn, and the thread-like connecting element extends in the cross machine direction over at least half the width, preferably over the entire width, of the fabric.

6. 5. The fabric according to claim 1 , wherein the at least one bonding element is in the form of a strip, in particular as a textile strip, nonwoven, film or foam, and the strip-shaped bonding element extends in the cross machine direction over at least half the width, preferably over the entire width, of the fabric.

7. A fabric described in any one of claims 1 to 4, wherein the absorption additive is used as a coating on the bonding element (20).

8. 8. A method for using a fabric (1) according to any one of claims 1 to 7, comprising the steps of first drawing the fabric (1) into a press section of a machine for producing a fibrous web, thereafter rendering the fabric endless by closing an interleaved wire seam, and then welding at least one joining element (20) to the laminated fibres of the seam flap (10) and / or seam wedge (11), and The method of claim 1, wherein the at least one coupling element is configured to be absorbent for light having a NIR wavelength range of 780 nm to 3 μm, in particular 780 nm to 1300 nm, and the coupling is performed by NIR transmembrane welding.

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