Laminated paper machine clothing

Abstract

The invention relates to a clothing (10) for a machine for producing or finishing a fibrous material web, in particular a paper, card or tissue web, comprising a substrate (40) and a lattice structure (20') applied to the substrate (40), on which lattice structure the fibrous material web is transported when the clothing (10) is used as intended, the lattice structure (20') comprising a plurality of first elements (24'), which are all oriented in a first direction, and a plurality of second elements (26'), which are all oriented in a second direction, which is different from the first direction, the first elements (24') passing through the second elements (26') so as to form the lattice structure (20') in such a way that an underside of the first elements (24') facing the substrate (40) and an underside of the second elements (26') facing the substrate (40) lie in a common plane. The present invention further relates to a method for producing such a clothing.

Description

[0001] The invention relates to a covering for a machine for the production or finishing of a fibrous web, in particular a paper, cardboard or tissue web, comprising a substrate and a grid structure applied to the substrate, on which the fibrous web is transported when the covering is used as intended, wherein the grid structure comprises a plurality of first elements, all of which are oriented in a first direction, and a plurality of second elements, all of which are oriented in a second direction that differs from the first direction.

[0002] Such a covering is known, for example, from WO 2017 / 139786 A1. In the covering described in WO 2017 / 139786 A1, the substrate formed from a fabric and the applied grid structure are connected in such a way that air channels are formed in the plane between the substrate and the grid structure. Structuring coverings are also known, for example, from US 2005 / 167062 A1 and US 2018 / 119347 A1.

[0003] A disadvantage of the covering known from the prior art is that the connection of the grid structure to the substrate is not optimal, or a correspondingly stable connection must be achieved using complex joining processes.

[0004] The object of the present invention is to provide a covering in which a reliable connection between the substrate and the grid structure can be achieved in a simple manner.

[0005] The problem is solved according to the invention by an embodiment according to claim 1, and by a manufacturing method for such a covering according to claim 9. Further advantageous features of the embodiment according to the invention are found in the dependent claims. According to the invention, the covering of the generic type and described at the outset is characterized in that the first elements penetrate the second elements to form the grid structure in such a way that an underside of the first elements facing the substrate and an underside of the second elements facing the substrate lie in a common plane. In contrast to the prior art described at the outset, both the first elements and the second elements thus provide a contact surface on their respective undersides, via which the grid structure can be attached to the substrate.A sufficiently large contact area makes it possible to achieve a reliable bond between the grid structure and the substrate even with relatively simple means, such as an adhesive. A reliable bond is of great importance to prevent premature failure, particularly delamination, of the covering during normal machine operation, where it is subjected to high and fluctuating loads.

[0006] Since all surfaces naturally exhibit a certain roughness and the lattice structure is also subject to manufacturing tolerances, the term "common plane" within the meaning of the present invention is to be understood as meaning that the underside of the first elements and the underside of the second elements should lie within a tolerance band that deviates from an ideal plane by no more than 10%, preferably no more than 5%, of the thickness of the lattice structure. This is intended to ensure that, for example, when the lattice structure is laid flat on a level surface, both the undersides of the first elements and the undersides of the second elements contact the surface, requiring no or only a minimal, evenly distributed compressive force of a maximum of 10 N / m² to be applied to the lattice structure.

[0007] In the context of the present invention, the term "penetrating" is to be understood broadly. Essentially, it is important that the lattice structure comprises elongated elements that intersect each other. Preferably, the elongated elements are bonded together at the intersections, in particular fused together. However, the lattice structure can also be manufactured in another way, for example, integrally in one piece by a casting process.

[0008] In a further development of the present invention, it is proposed that an adhesive layer be arranged between the substrate and the grid structure, bonding the substrate to the grid structure, wherein the adhesive layer preferably comprises a moisture-curing thermoplastic material. Good results were also achieved in tests with a reactive hot melt adhesive based on polyurethane. Such an adhesive is offered commercially, for example, by Kleiberit under number 716.8. In particular, the reactive hot melt adhesive based on polyurethane offered by Kleiberit under number 704.6 has yielded very good results.

[0009] To ensure reliable bonding of the lattice structure to the substrate even using simple means, such as an adhesive, it is further proposed that the first and second elements provide a contact area in the common plane defined by the underside of the first and second elements, comprising at least 40%, preferably at least 50%, and more preferably at least 60%, of the total planar dimension of the lattice structure. The contact area preferably lies in the common plane.

[0010] According to the invention, the upper surface of the first elements facing away from the substrate and the upper surface of the second elements facing away from the substrate do not lie in a common plane. This results in a structuring surface on the side of the grid structure facing away from the substrate, on which the fiber web to be produced or finished is transported when the covering is used as intended in the machine. This surface allows structures to be transferred onto the fiber web, which is particularly important for tissue.

[0011] Preferably, the first elements and / or the second elements have essentially the same cross-section along their longitudinal direction, perpendicular to that direction. This cross-section can, for example, be essentially rectangular, round, or oval, or a combination of these shapes. This makes the lattice structure particularly easy to manufacture. For example, the first elements and the second elements can be extruded and then joined together to form the structure described above.

[0012] Preferably, the first and second elements have different heights. The distance between the underside and an upper surface of the first elements can differ by at least 20%, preferably by at least 30%, from the distance between the underside and an upper surface of the second elements. In particular, the difference can be between 20% and 40%.

[0013] In principle, the grid structure can be formed solely from the first and second elements. If the first and second directions form an angle of 90°, a rectangular grid structure results. If this angle deviates from 90°, a rhomboid grid structure results.

[0014] In a modification of the present invention, the lattice structure may also comprise at least a plurality of further elements, all of which are oriented in a further direction that differs from the first and second directions, preferably with a substrate-facing underside of the further elements lying in the common plane defined by the underside of the first elements and the underside of the second elements. If the lattice structure is formed, for example, from first elements, second elements, and third elements, the lattice structure may be honeycomb-shaped.

[0015] The substrate is preferably a fabric consisting of warp and weft threads, in particular a single-layer fabric. However, the substrate may alternatively or additionally comprise at least one layer or ply formed from a perforated film, in particular a die-cut or laser-drilled film, a woven fabric, a felt, a spiral screen, or combinations thereof. The substrate may consist predominantly or entirely of PEZ and / or PPS and / or PA and / or PCTA.

[0016] The lattice structure can comprise, and preferably be formed from, a TPU material. TPU stands for thermoplastic elastomers based on urethane. Alternatively or additionally, the lattice structure can also comprise, or be formed from, for example, TPE, PET, PP, and / or PA. Preferably, the material from which the lattice structure is made is easy to extrude in order to facilitate its production.

[0017] The present invention further relates to a machine for producing or finishing a fibrous web, in particular a paper, cardboard or tissue web, comprising a screen according to one of the preceding claims, wherein the screen is preferably used in the machine as a structured TAD screen. TAD stands for Through-Air-Dryer and such screens are used in particular in the production of tissue, which is used, for example, for toilet paper, facial tissues, etc.

[0018] Alternatively, the fabric according to the invention can be used as a so-called molding screen in an Atmos machine from Voith. Currently, woven, structured forming screens are used as molding screens for this application. Depending on the design of the grid structure, the fabric according to the invention makes it possible to increase the contact area of ​​the molding screen with the Yankee cylinder. Furthermore, with a suitable choice of material, the grid structure can exhibit significantly more elastic properties than the previously used woven, structured forming screens. This allows the contact area in the press nip to be significantly increased due to its compressibility and elasticity, resulting in greater dewatering during the press nip pass. Consequently, higher dry contents can be achieved, the machine speed increased, and the production capacity and efficiency of the system improved.

[0019] The fabrication according to the invention can also be used in an NTT machine from Valmet, in particular as a structured NTT belt for such a machine. The structuring of the paper web is essentially determined by the design of the grid structure. If a defined permeability of the finished fabrication is to be achieved in the final application, this can be specifically adjusted not only by the design of the grid structure and the selection of the substrate, but also, or alternatively, by the quantity and type of adhesive.

[0020] Furthermore, the fabric according to the invention can be used in the forming section of a conventional paper machine as a so-called forming wire. The fabric according to the invention offers several advantages over conventional forming wire, which is only woven. For example, the fabric according to the invention can be manufactured more economically because its production is less complex, generally requires fewer work steps, and can be standardized more effectively. Conventional forming wire, on the other hand, typically has relatively complex weave patterns. Moreover, the fabric according to the invention allows for faster dewatering with consistent paper properties compared to conventional forming wire, as well as improved runnability due to a cleaner run, since there are fewer cavities for fiber adhesion and / or contamination.

[0021] The use of the covering according to the invention as so-called marking tapes in various industrial applications is also conceivable.

[0022] According to the present invention, a method for producing the previously described covering is further proposed, in which the substrate and the grid structure are produced separately and then glued together.

[0023] First, adhesive can be applied to the grid structure, preferably to the underside of the first elements facing the substrate and to the underside of the second elements of the grid structure facing the substrate, before the grid structure is laminated onto the substrate.

[0024] To achieve an adhesive viscosity that allows for reliable wetting of the underside of the first elements and the underside of the second elements, while leaving the openings in the grid structure clear, it is proposed that the adhesive be heated to a temperature above 100°C, preferably between 110°C and 130°C, before application to the grid structure. Particularly when using a reactive polyurethane-based hot melt adhesive, as described above, good results have been achieved by heating to these temperatures.

[0025] Furthermore, to achieve good results, it is proposed that between 40g / m²< and 80g / m²< of the adhesive be applied to the grid structure, preferably between 45g / m²< and 55g / m²<. This ensures, on the one hand, a reliable bond between the grid structure and the substrate and, on the other hand, prevents excess adhesive from flowing into the openings of the grid structure.

[0026] The adhesive can first be applied to a roller, which together with a counter roller forms a nip through which the grid structure is passed for wetting with the adhesive.

[0027] Alternatively, the adhesive can also be sprayed onto the grid structure to wet it. Good results were also achieved here with a polyurethane-based hot melt adhesive, such as those commercially available from Kleiberit under numbers 704.6 or 716.8. Spraying this adhesive also resulted in complete wetting of the underside of the first elements and the underside of the second elements, without the adhesive reducing the size of or even blocking the openings in the grid structure.

[0028] The coated grid structure can then be laminated onto the substrate, to which preferably no adhesive has been applied beforehand, for example by passing the adhesive-coated grid structure together with the substrate through a roller nip. In principle, the grid structure can have essentially the same width as the substrate, or it can be narrower. In the latter case, several separate webs of the grid structure can be arranged side by side on the substrate, or a continuous web can be spiraled onto the substrate.

[0029] Further advantageous embodiments of the invention are explained using exemplary embodiments with reference to the drawings. The features mentioned can be advantageously implemented not only in the combination shown, but also individually combined with one another. The figures, not to scale, show in detail: Fig.1 a section of a lattice structure according to a first embodiment, Fig. 2 section through plane II-II in Figure 1 , Fig.3 Section through plane III-III in Figure 1 , Fig. 4 a section of a lattice structure according to a second embodiment, Fig. 5 a section through plane VV in Figure 4 , supplemented by an adhesive layer and a substrate.

[0030] The characters are described in more detail below. Figure 1 Figure 20 shows a small section of a grid structure enclosed by a dashed line. The viewing direction is in Figure 1directed towards the underside 22 of the grid structure, i.e. the side which, in the finished covering, faces the substrate 40 (see Figure 5 ) is facing. The grid structure 20 consists of a multitude of first elements 24, all of which are aligned parallel to each other and in Figure 1 running in a vertical direction, and a multitude of second elements 26, which are also all formed parallel to each other and in Figure 2The first elements 24 and the second elements 26 extend in a horizontal direction. They interpenetrate to form the lattice structure 20. The first elements 24 and the second elements 26 can be made of an extrudable plastic, such as TPU, and then fused together to form the lattice. In the present embodiment, the distance between the first elements 24 is constant and corresponds to the distance between the second elements 26, which is also constant. This results in a regular arrangement of essentially rectangular, in particular square, openings 28 in the lattice structure 20. Due to the manufacturing process, in which the first elements 24 and the second elements 26 are fused together, the openings 28 do not necessarily have to be sharp-edged, but can have somewhat rounded corners, as illustrated in the present embodiment.The surface formed by a bottom surface 30 of the first elements 24 and a bottom surface 32 of the second elements 26 is essentially planar and makes in . Figure 1 at least 60% of the total area, i.e. the area enclosed by the dashed frame in Figure 1 is surrounded. Thus, a sufficiently large contact area is provided for a reliable bonding of the grid structure 20 to the substrate 40, even with simple means such as an adhesive.

[0031] In Figure 2 is a section through plane II - II in Figure 1 shown. Here it can be seen that the first element 24 has a greater thickness, i.e., dimension in the vertical direction. Figure 2, exhibits a larger dimension than the second element 26. In other words, the dimension of the underside 30 relative to a top surface 34 of the first element 24 is larger than the dimension of the underside 32 relative to a top surface 36 of the second element 26. Since the underside 30 of the first element 24 and the underside 32 of the second element 26 lie in the same plane, this results in a profile of the top surface of the grid structure 20, i.e., the side which, in the intended use of the covering 10 (see Figure 5 ) facing the fiber web to be produced or refined. This profiling is advantageously imprinted on the fiber web, which thus exhibits not only the pattern of openings 28, but also the pattern of parallel grooves achieved by the different heights of the first elements 24 and second elements 26. As in Figure 2Furthermore, as can be seen, the first elements 24 can have a cross-section orthogonal to their longitudinal direction, which is rounded at the top, so that the upper surface 24 of the first element 24 is essentially formed only by a line running in the longitudinal direction of the first element 24. The second element 26 can be configured similarly, but with a lower height. Preferably, both the first elements 24 and the second elements 26 have essentially the same cross-section along their entire length, orthogonal to their longitudinal direction. Due to the manufacturing process, the material may overlap at the intersection points of the first elements 24 and the second elements 26, which can lead to rounded corners of the openings 28, as previously described.

[0032] Figure 3 shows a section through plane III - III in Figure 1For the sake of simplicity, only the first element 24 is shown in this figure and not the second elements 26, which are completely merged with the first element 24 in this sectional view.

[0033] Figure 4 shows a view identical to that in Figure 1 , however, from a second embodiment of a lattice structure 20'. Identical features of the second embodiment are provided with identical reference numerals as in the first embodiment, but with an additional line. In this respect, reference is made to the description above.

[0034] The second embodiment differs from the first embodiment only in that the distance between the second elements 26' is greater than the distance between the first elements 24'. Thus, the resulting openings 28' are not substantially square, but substantially rectangular with an elongated shape.

[0035] In Figure 5is a section through plane V - V in Figure 4 This section view essentially corresponds to the section view in Figure 2 to the first embodiment. However, in Figure 5 In addition to the grid structure 20', the substrate 40 is also shown, which in this embodiment consists of a single-layer fabric with warp and weft threads, and an adhesive layer 38 arranged between the grid structure 20' and the substrate 40. Thus, Figure 5 a section of the finished covering bounded by a dashed frame 10.

[0036] The covering 10 is produced by first manufacturing the grid structure 20' and the substrate 40 separately. Then the grid structure 20' is coated with the adhesive layer 38 and subsequently laminated onto the substrate.

[0037] Both in the first embodiment according to the Figures 1-3 , as well as in the second embodiment according to the Figures 4 and 5Preferably, when the covering 10 is used as intended, the first elements 24, 24' extend in the machine direction and the second elements 26, 26' extend in the machine transverse direction. Alternatively, however, the first elements 24, 24' can also extend in the machine transverse direction and the second elements 26, 26' in the machine direction. List of reference symbols

[0038] 10 Covering 20, 20' Grid structure 22 Underside of grid structure 24, 24' First elements 26, 26' Second elements 28, 28' Openings 30 Underside of first elements 32 Underside of second elements 34 Top of first element 36 Top of second element 38 Adhesive layer 40 Substrate

Claims

1. Structured covering (10) for a machine for producing or refining a fibrous web, in particular a paper, cardboard or tissue web, including a substrate (40) and a grid structure (20, 20'), applied on the substrate (40), on which grid structure the fibrous web is transported in case of intended use of the structured covering (10), whereby the grid structure (20, 20') includes a plurality of first elements (24, 24'), which are all oriented in a first direction, and a plurality of second elements (26, 26'), which are all oriented in a second direction, which differs from the first direction, characterised in that the first elements (24, 24') run through the second elements (26, 26') while forming the grid structure (20, 20') such that a bottom side (30) of the first elements (24, 24') facing the substrate (40) and a bottom side (32) of the second elements (26, 26') facing the substrate (40) lie on a common plane; wherein the plurality of first elements (24, 24') extends continuously through the structured covering in the first direction and the plurality of second elements (26, 26') extends continuously through the structured covering in the second direction, and the whole top side (34) of each first element (24, 24') turned away from the substrate (40) does not lie on a common plane with the whole top side (36) of each second element (26, 26') turned away from the substrate (40).

2. Structured covering (10) according to claim 1, characterised in that between the substrate (40) and the grid structure (20, 20') an adhesive layer (38) is arranged which joins the substrate (40) with the grid structure (20, 20'), whereby the adhesive layer (38) preferably includes, or is composed of, a thermoplastic material hardening under humidity or a reactive hot-melt adhesive based on polyurethane.

3. Structured covering (10) according to claim 1 or 2, characterised in that the first elements (24, 24') and the second elements (26, 26') provide on the common plane, which is defined by the bottom side (30) of the first elements (24, 24') and the bottom side (32) of the second elements (26, 26'), a contact surface which constitutes at least 40%, preferably at least 50%, more preferably at least 60%, of the planar overall dimension of the grid structure (20, 20').

4. Structured covering (10) according to any of the preceding claims, characterised in that a distance between the bottom side (30) and a top side (34) of the first elements (24, 24') differs by at least 20%, preferably by at least 30%, from a distance between the bottom side (32) and a top side (36) of the second elements (26, 26').

5. Structured covering (10) according to any of the preceding claims, characterised in that the grid structure (20, 20') further includes at least a plurality of further elements which are all oriented in a further direction which differs from the first direction and from the second direction, whereby preferably also a bottom side of the further elements facing the substrate (40) lies on the common plane which is defined by the bottom side (30) of the first elements (24, 24') and the bottom side (32) of the second elements (26, 26').

6. Structured covering (10) according to any of the preceding claims, characterised in that the substrate (40) is a fabric, preferably a one-layer fabric, made up of warp threads and weft threads.

7. Structured covering (10) according to any of the preceding claims, characterised in that the grid structure (20, 20') includes, preferably is composed of, TPU-material.

8. Machine for producing or refining a fibrous web, in particular a paper, cardboard or tissue web, including a structured covering (10) according to any of the preceding claims, whereby the structured covering (10) is preferably used as structured TAD sieve in the machine.

9. Method for the production of a structured covering (10) according to any of the claims from 1 to 7, whereby the substrate (40) and the grid structure (20, 20') are produced separately and subsequently are adhered to each other.

10. Method according to claim 9, whereby firstly adhesive is applied onto the grid structure (20, 20'), preferably onto the bottom side (30) of the first elements (24, 24') facing the substrate (40) and onto the bottom side (32) of the second elements (26, 26') of the grid structure (20, 20') facing the substrate (40), before the grid structure (20, 20') is laminated on the substrate (40).

11. Method according to claim 10, whereby the adhesive before the application onto the grid structure (20, 20') is heated up to a temperature over 100°C, preferably up to a temperature between 110°C and 130°C.

12. Method according to claim 10 or 11, whereby between 40 g / m2 and 80 g / m2, preferably between 45 g / m2 and 55 g / m2, of the adhesive are applied onto the grid structure (20, 20').

13. Method according to any of the claims from 10 to 12, whereby the adhesive is firstly applied on a roll, which together with a counter roll forms a nip through which the grid structure (20, 20') is passed through for wetting with the adhesive.

14. Method according to any of the claims from 10 to 12, whereby the adhesive is sprayed on the grid structure (20, 20') for wetting.

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