Press cover, the use thereof, and the use of a thermoplastic elastomer in the form of a copolymer for a polymer layer of a press cover

Abstract

The invention relates to a press cover comprising at least one polymer layer, wherein the at least one polymer layer comprises or is produced from at least one thermoplastic elastomer in the form of a copolymer. Furthermore, the invention also relates to the use of a press cover of this type in a shoe press, to a shoe press of this type, and to a press roll, in each case comprising a press cover of this type. Finally, the invention also relates to the use of a thermoplastic elastomer in the form of a copolymer, for at least one polymer layer of a press cover for a shoe press for the treatment of a fibrous web.

Description

[0001] The invention relates to a press jacket for a press device for treating a fibrous web, e.g., for smoothing or dewatering it, as detailed in the independent claims. The invention also relates to a shoe press and the use of a press jacket in such a press, as well as a machine comprising such a shoe press, as detailed in the dependent claims.

[0002] Pressing devices such as shoe presses have long been an integral part of modern paper machines. They essentially comprise a stationary shoe (also called a press shoe) that extends transversely in one direction of the machine and a press sleeve that encircles the stationary shoe. The latter is deformable and, during operation, essentially assumes a tubular shape. The shoe is shaped so that it forms a press nip (press gap) with a counter roller. The press nip is defined by the contact surface of the counter roller within the shoe. The shoe is designed to be movable and can be moved against the counter roller.

[0003] The press sleeve is subjected to enormous demands regarding its stability, namely surface hardness, resistance to pressure, temperature, and hydrolysis. Furthermore, the press sleeve is exposed to severe alternating bending loads during operation. Upon entering the shoe edge – viewed in the direction of rotation of the press sleeve, before the press nip – it initially bends with a relatively small radius. This immediately transitions into a counter-bend as it passes through the press nip. Upon exiting the shoe edge – viewed in the direction of rotation of the press sleeve, after the press nip – another counter-bend occurs. This deformation of the press sleeve during entry and exit is also known as the alternating nip. It is readily apparent that the high mechanical stress makes the press sleeve particularly prone to breakage at this point.Accordingly, many measures are known from the state of the art that are intended to increase the stability of the press jacket.

[0004] The press-fit sleeve must therefore be sufficiently flexible to allow it to be guided around the shoe, sufficiently stiff to prevent excessive deformation or compression in the nip under the pressing load, and sufficiently wear-resistant. Press-fit sleeves thus consist of a single- or multi-layer polymer layer, preferably polyurethane, into which reinforcing threads in the form of non-woven or woven fabrics may be embedded.

[0005] A press jacket for a press device for treating a fibrous web, comprising at least one polymer layer, wherein the at least one polymer layer comprises or is made from at least one thermoplastic elastomer, as well as the use of the press jacket for a press for treating a fibrous web and the use of a thermoplastic elastomer for at least one polymer layer of a press jacket for a shoe press for treating a fibrous web, is known from European patent EP 1 507 042 A1. For the sake of completeness, reference should also be made to European patent WO 2019 / 011558 A1.

[0006] The present invention relates to such generic items mentioned at the outset.

[0007] Although press jackets known from the prior art exhibit sufficient flexibility and at the same time sufficient stiffness, their chemical resistance, especially to water and oil, their abrasion resistance, their resistance to cracking and crack growth, and their swelling behavior require improvement.

[0008] The object of the invention is therefore to provide a press jacket which avoids the disadvantages of the prior art.

[0009] The problem is solved by the features of the independent claims. Particularly preferred and advantageous embodiments of the invention are described in the dependent claims.

[0010] The inventor has recognized that the problem according to the invention is solved if a thermoplastic elastomer (TPE) in the form of a copolymer is used for a polymer layer of the press jacket.

[0011] Thermoplastic elastomers, according to the definition in the Wikipedia article of the same name (last edited on July 22, 2019 at 11:13 AM), are materials in which elastic polymer chains are embedded in a thermoplastic material. They can be processed in a purely physical process involving a combination of high shear forces, heat, and subsequent cooling. In contrast, conventional elastomers are chemically cross-linked, three-dimensional network molecules. These cross-links cannot be broken without decomposing the material. Although no chemical cross-linking, such as through the time- and temperature-intensive vulcanization process required for elastomers, is necessary, the manufactured parts nevertheless exhibit rubber-like elastic properties due to their unique molecular structure. Re-exposure to heat and shear forces leads to the re-melting and deformation of the material.

[0012] Copolymers within the meaning of the invention are polymers composed of two or more different monomer units. According to the Wikipedia article mentioned at the beginning, thermoplastic elastomers are distinguished into copolymers and elastomer alloys. Copolymers are used either as statistical or block copolymers. The former consist of a crystallizing (and thus physically crosslinking) main polymer such as polyethylene, the degree of crystallinity of which is reduced by a comonomer such as vinyl acetate randomly incorporated along the chain to such an extent that the crystallites (= the hard phase) no longer have direct contact in the finished material (in the example, EVA). They then act as isolated crosslinking points, as in conventional elastomers. In block copolymers, the hard and soft segments are sharply separated within a molecule (e.g., SBS, SIS).In TPEs, below a certain temperature the material separates into a continuous and a discontinuous phase. As soon as the latter falls below its glass transition temperature Tg (the Tg of the continuous phase is significantly below the later application temperature), it acts as a crosslinking point. Elastomer alloys, on the other hand, are polyblends, i.e., mixtures of finished polymers; the plastic therefore consists of several types of molecules. Different mixing ratios and additives allow for the creation of customized materials (for example, polyolefin elastomers made from polypropylene (PP) and natural rubber (NR) – depending on the proportions, they cover a wide range of hardness).

[0013] Preferably, the thermoplastic elastomer is a segmented block copolymer. Such a copolymer can be a thermoplastic polyetherester block copolymer (COPE or TPE-E) and / or a thermoplastic copolyamide elastomer (COPA or TPE-A). These two polymers can be alternatives to conventional polyurethanes or thermoplastic polyurethanes (TPU). The soft segments are formed by the polyol. For the hard segments of COPE, polyesters, polybutylene tetetephthalates, polyethylene terephthalates, methyl terephthalates, poly(butylene 2,6-napthalene dicarboxylate), poly(butylene-co-isophthalate), or aromatic polycarbonates can be used. For COPA, polyamides can be used as the hard segments. Polyether polyols, such as polytetramethylene glycol, polycarbonate polyols, polyether-polycarbonate polyols, and polycaprolactone polyols are particularly suitable for the invention.

[0014] In principle, it would be conceivable to use a polyol blend, i.e., an elastomer alloy between the aforementioned thermoplastic copolymers and a urethane-based thermoplastic elastomer (TPU), for at least one polymer layer of the press jacket.

[0015] When the invention refers to something being made from a material, it means that it is made partly or completely from such a material.

[0016] The molded casing, or at least one polymer layer, can be made partially or completely from a polymer. A castable, curable, preferably elastomeric polymer such as polyurethane can be used as the polymer. The polymer can therefore be formulated as a cast elastomer.

[0017] A polymer layer is defined as a layer comprising or entirely composed of such a castable, curable, preferably elastomeric polymer. Preferably, the polymer layer can be a cured layer produced in one piece by primary forming. In other words, it is monolithically primary formed, i.e., produced by, for example, casting. The term "one piece" also includes cases in which the single layer was produced from several layers of the same material during the casting of the polymer. However, this only applies insofar as these layers are essentially no longer visible after curing, resulting in a single, preferably uniform, layer. The same applies accordingly to the finished press jacket.

[0018] When multiple polymer layers are used, these can be arranged one above the other in the radial direction – at least partially across the width of the mold. "At least partially across the width of the mold" means that the mold, for example, is only a single layer at its axial ends along its longitudinal axis, whereas it is two or more layers between the axial ends. However, the polymer layers can also extend across the entire width of the mold. Furthermore, the thickness of the mold – and thus the thickness of the individual polymer layers – can vary section by section along its longitudinal axis in a cross-section. For example, the outermost polymer layer radially can be thinner at the edges of the mold than in the center.In other words, in the region of the lateral edges, the radially outermost polymer layer can be thinner than a radially inner or radially innermost polymer layer. Preferably, exactly one, two, or three polymer layers are provided. These can be identical with respect to their polymer composition or vary with respect to the hardness or stoichiometry of the prepolymer. The total thickness of the finished press jacket, measured in a section through its longitudinal axis in the radial direction, can be 5 to 10 mm, preferably 5 to 7 mm, and particularly preferably 5 to 6 mm. According to the invention, if a single layer is provided, the press jacket can be produced in a single casting, i.e., monolithically, so that the single layer has the aforementioned thickness.

[0019] A finished press jacket within the meaning of the invention is one in which at least one polymer layer has been cured and possibly finished, i.e., is ready for use in, for example, a shoe press for the aforementioned purpose. Similarly, a finished polymer layer is defined as a layer that has been cured.

[0020] A reinforcing thread within the meaning of the invention is understood to be a flexible, textile linear structure that exhibits a dominant extent and uniformity in its longitudinal direction. When the term "fiber" is used, it refers to a single, continuous fiber such as a monofilament. However, when the term "fiber bundle" is used within the meaning of the invention, it does not refer to monofilaments but rather to a single thread, such as a twisted yarn or thread, i.e., a bundle of continuous fibers or monofilaments. The fiber bundles themselves may well be made of fibers twisted together.

[0021] The definition that at least the longitudinal threads are manufactured as reinforcing threads according to the invention means that only the longitudinal threads are designed in this way, or additionally the longitudinal threads and at least one further circumferential thread are manufactured in this way. If, for example, a fabric consisting of circumferential and longitudinal threads is preferably present, then this means that at least the longitudinal threads are designed according to the invention.

[0022] In the context of the invention, the term "reinforcing structure" refers to the reinforcement of at least one layer containing or consisting of the polymer—that is, the polymer layer. The reinforcing structure can be completely embedded within the polymer layer, such that it does not extend beyond the boundaries of the polymer layer. In other words, the polymer layer acts as a matrix that surrounds the reinforcing structure and binds it to the matrix through adhesion or cohesion. Such a reinforcing structure can comprise textile linear structures—e.g., yarns or threads—and / or textile sheet structures—such as woven, knitted, braided, or non-woven fabrics—and can be produced from a suitable starting material, e.g., by winding. In other words, a single reinforcing thread according to the invention is, in itself, a textile linear structure.Several such reinforcing threads can be configured, for example as longitudinal and / or circumferential threads, to form a textile surface structure. The at least one reinforcing thread embedded in the at least one polymer layer then constitutes the reinforcing structure of the press jacket or its polymer layer. The starting material is understood to be the material or semi-finished product used to manufacture the reinforcing structure of the finished press jacket according to the invention, i.e., in this case, the at least one reinforcing thread.

[0023] The reinforcing thread or structure can be made of or comprise a polymer. Suitable polymers include polyester, polyethylene naphthalate, or polyamides such as aramids. The materials of the at least one polymer layer and the at least one reinforcing thread or structure embedded within it differ accordingly.

[0024] For the purposes of the invention, a pressing device is, for example, a shoe press used for dewatering or treating, such as smoothing, a fibrous web. The shoe press comprises a press roller and a counter roller, which together form or define a press nip. The press roller further comprises a rotating press shell and a stationary press element, the so-called press shoe. The latter is supported on a load-bearing, also stationary, yoke – for example, via hydraulic press elements – and is pressed against the rotating press shell. The press shell rotates relative to the stationary press shoe and yoke and is thereby pressed against the counter roller in the press nip. The press shoe and yoke are arranged radially within the press shell.The term "pressing element" refers to the fact that the pressing element does not rotate relative to the shoe press roller or the counter roller, but can move translationally—towards and away from the counter roller, preferably in its radial direction—and thus relative to the counter roller. In addition to the fiber web and the press sleeve, one or more circumferentially circulating press felts and / or further circumferentially circulating press belts can be guided through the press nip of the shoe press. Such a shoe press can, of course, include more than one press nip.

[0025] A fibrous web within the meaning of the invention is understood to be a woven or tangled mass of fibers, such as wood fibers, plastic fibers, glass fibers, carbon fibers, additives, or the like. The fibrous web can, for example, be designed as a paper, cardboard, or tissue web. It can essentially comprise wood fibers, with small quantities of other fibers or additives also being present. This is left to the expert's discretion, depending on the application.

[0026] Preferably, several reinforcing threads are embedded as longitudinal threads and at least one reinforcing thread as a circumferential thread, which surrounds the longitudinal threads in the circumferential direction, in the polymer layer as a non-woven fabric, then the advantages of the invention are particularly well fulfilled. This is because a non-woven fabric is particularly well able to absorb local overloads.

[0027] The advantages of the invention are particularly well achieved when the press jacket is constructed from preferably several polymer layers arranged one above the other in the radial direction. If two polymer layers are provided, then the radially inner one is the one with the reinforcement structure according to the invention. This means that the reinforcement structure is arranged only in the radially innermost polymer layer. If three or more polymer layers are provided, then the reinforcement structure is preferably arranged in the second lowest polymer layer, i.e., in the one that lies radially above the radially innermost polymer layer.

[0028] Furthermore, the invention also relates to a press roller, such as a shoe press roller, for a shoe press for treating a fibrous web, characterized in that the press roller has at least one press jacket according to one of the preceding claims.

[0029] The invention also relates to a shoe press for treating a fibrous web, preferably a paper, cardboard, tissue or pulp web, comprising a press roller and a counter roller which together form or limit a nip, wherein the press roller comprises a circumferential press sleeve, characterized in that the press sleeve is designed according to the invention.

[0030] The invention further relates to the use of a press jacket according to the invention for a press, such as a shoe press, for the treatment of a fibrous web, preferably a paper, cardboard, tissue or cellulose web.

[0031] The invention also relates to the use of a thermoplastic elastomer in the form of a copolymer, preferably a segmented block copolymer, which is preferably a thermoplastic copolyester elastomer (COPE) and / or a thermoplastic copolyamide elastomer (COPA), for at least one polymer layer of a press jacket for a shoe press for treating a fibrous web.

[0032] The invention is explained in more detail below with reference to the drawings, without limitation of generality. The drawings show: Fig. 1 is a partially cutaway, schematic side view of a shoe press with a press jacket according to an embodiment of the present invention. Figs. 2a and 2b show embodiments of a press jacket, each seen in a section through its longitudinal axis; Fig. 3 is a highly schematic representation of a device for manufacturing the press jacket in a side view.

[0033] In the Fig. 1 A partially cutaway, schematic side view shows a shoe press 10, which in this case comprises a press roller according to the invention, such as shoe press roller 12, and a counter roller 14. Shoe press roller 12 and counter roller 14 are arranged parallel to each other with respect to their longitudinal axes. Together they form or define a nip 22. While the counter roller 14 consists of a cylindrically shaped roller rotating about its longitudinal axis, the shoe press roller 12 is composed of a shoe 16, a stationary yoke 18 supporting it, and a press shell 20. The shoe 16 and yoke 18 are fixed relative to the counter roller 14 and the press shell 20, respectively. This means they do not rotate. The shoe 16 is supported by the yoke 18 and pressed against the radially innermost surface of the press shell 20, which rotates relative to it, by means of hydraulic pressing elements (not shown).The press jacket 20, which surrounds the shoe 16 and yoke 18 circumferentially, rotates about its longitudinal axis in the opposite direction to the counter roller 14. Due to the concave design of the shoe 16 on its side facing the counter roller 14, a comparatively long nip 22 results.

[0034] The shoe press 10 is particularly suitable for dewatering fiber webs 24. During operation of the shoe press, a fiber web 24 is guided through the press gap 22 with one or two press felts 26, 26'. In this case, there are exactly two press felts 26, 26' that sandwich the fiber web 24 between them. As it passes through the nip 22, pressure is indirectly exerted on the fiber web 24 by the press felts 26, 26'. This occurs because the radially outermost surface of the counter roller 14 and the radially outermost surface of the press shell 20 come into direct contact with the corresponding press felts 26, 26'. The liquid emerging from the fiber web 24 is temporarily absorbed by the press felt(s) 26, 26' and any recesses (not shown) provided in the surface of the press shell.After exiting the nip 22, the liquid absorbed by the recesses of the press jacket 20 is flung off before the press jacket 20 re-enters the press gap 22. Additionally, the water absorbed by the press felt 26, 26' after exiting the press gap 22 can be removed by suction elements.

[0035] In a further embodiment of the invention, not shown in the figures, the press felts 26, 26' can be omitted. In such a case, the fiber web 24 is in direct contact on the one hand with the press jacket 20 and on the other hand with the counter roller 14, which together form a press nip. The latter can then be designed as a heated drying cylinder.

[0036] The in Fig. 1 The press jacket shown can be designed according to the invention, as shown in the following figures.

[0037] In the Fig. 2a und 2b Different embodiments of the invention are shown in a partially drawn cross-section through the longitudinal axis 20' of the finished press jacket 20, which is not to scale. The distance of the longitudinal axis 20' to the radially innermost surface of the corresponding polymer layer of the press jacket 20 is also not to scale.

[0038] According to the Fig. 2a Exactly two polymer layers are provided, namely a first 20.1 and a second 20.2. In the present case, the first polymer layer 20.1 is also the radially outermost polymer layer of the press jacket 20. In contrast, the second polymer layer 20.2 is also the radially innermost polymer layer of the press jacket 20.

[0039] As shown, a reinforcing structure 20" can be provided in the second polymer layer 20.2. In this case, it is completely embedded in the polymer layer 20.2. This is indicated by the hatched circles, which can be textile surface or line structures such as fibers. This means that the reinforcing structure 20" does not extend beyond the boundaries of the polymer layer 20.2.

[0040] The reinforcing structure 20" comprises a plurality of reinforcing threads 21 serving as longitudinal threads 21.1. These are arranged longitudinally around the circumference of the press jacket 20, spaced apart and running parallel to one another. Additionally, at least one further reinforcing thread 21 is provided as a circumferential thread 21.2, which preferably runs helically around the circumference of the press jacket within the same polymer layer 20.1, 20.2, 20.3 in which the longitudinal threads 21.1 are also arranged. The longitudinal threads 21.1 and the circumferential thread 21.2 form a fabric together, such that the longitudinal threads 21.1 are arranged radially within the at least one circumferential thread 21.2 – viewed with respect to the longitudinal axis 20' of the press jacket 20.

[0041] Figur 2b shows in a variation to Fig. 2a a three-layer press-molded casing. This comprises a first polymer layer 20.1 (here radially outermost), a third polymer layer 20.3 (radially innermost), and a second polymer layer 20.2 sandwiched between these two. The arrangement refers – as also shown in the illustration of the Fig. 2a - starting from the longitudinal axis 20' of the press shell 20, viewed in its radial direction. In this case, only a (single) reinforcing structure 20" is provided in the second polymer layer 20.2. Of course, this could also be different, so that alternatively or additionally such a reinforcing structure 20" could also be arranged in the first polymer layer 20.1 and / or the third polymer layer 20.3.

[0042] In the present case, one of the [unclear] can be [unclear] in the Fig. 2a und 2b The polymer layers 20.1, 20.2, or 20.3 shown are made of, or comprise, a thermoplastic elastomer according to the invention in the form of a copolymer. This could be the case, for example, for the radially innermost and / or the radially outermost polymer layer. The remaining polymer layers could then be made of a polyurethane. This is obtainable, for example, from a prepolymer and a crosslinker. The respective prepolymer itself is obtainable by reacting an isocyanate with a polyol.

[0043] Fig. 3 Figure 1 shows a highly schematic side view of a device for producing a press jacket 20 according to the invention. The device comprises exactly one cylindrical winding mandrel 4, onto whose radially outermost surface, for example, a starting material 20‴ is spirally applied. After being embedded in the polymer, the starting material 20‴′ forms the reinforcing structure 20" of the finished press jacket 20 according to the invention.

[0044] The illustration shows an initial stage of the manufacturing process. In this case, one end of the starting material 20‴ is attached to a polymer arranged on the outer circumference of the winding mandrel 4. Apart from the schematic representation shown, one end of the starting material 20‴ could also rest directly on or be applied to the winding mandrel 4 without an initial polymer layer between the starting material 20‴ and the winding mandrel 4. The starting material 20‴ can be a textile sheet or a linear structure.

[0045] The winding mandrel 4 is rotatably mounted about its longitudinal axis 20', which corresponds to the longitudinal axis of the press jacket to be produced. Longitudinal axis 20' runs perpendicularly into the plane of the drawing. A casting material, such as a pourable, curable elastomeric polymer, here e.g., polyurethane, is injected from above via a line 5 and a casting nozzle 6 onto the radially outermost surface of the winding mandrel 4, i.e., onto the starting material 20'. Such a casting material can be selected, for example, with regard to its pot life and viscosity, so that it does not drip off the winding mandrel 4 during casting. Meanwhile, the winding mandrel 4 is rotated about its longitudinal axis in the direction of the arrow. Simultaneously with this rotation, the casting nozzle 6 is opened via a suitable, in Fig. 3 The guide (not shown) runs parallel to the longitudinal axis 20' along this axis relative to the winding mandrel 4. Simultaneously with the pouring of the casting material, the starting material 20‴ is unwound and wound into coils on the rotating winding mandrel 4. The casting material can pass through the starting material 20‴ and onto the winding mandrel 4. In this example, after the curing step, the polymer forms a radially innermost and preferably elastomeric polymer layer, which corresponds to the polymer layer 20.2 of the press jacket. Fig. 2a corresponds to which in Fig. 3 Only a part is shown.

[0046] The casting material emerging from the casting nozzle 6 is a mixture of a prepolymer and a crosslinker. The prepolymer is supplied from a prepolymer container (not shown), in which it is stored or mixed. The prepolymer is the reaction product of an isocyanate and a polyol. In the prepolymer container, it can, for example, be present as a prepolymer made from the aforementioned substances.

[0047] The crosslinker can be provided in a crosslinker container.

[0048] Prepolymer containers and crosslinker containers are associated with the device for producing a press jacket 20. They are connected via flow-conducting lines (not shown) to a mixing chamber (not shown) located upstream of the casting nozzle 6 in the flow direction. The prepolymer-crosslinker mixture is thus produced upstream and outside the casting nozzle 6, i.e., mixed in the mixing chamber. Independently of the production of the mixture, it is then applied to the surface of the winding mandrel 4 to form at least one polymer layer of the press jacket 20.

[0049] In principle, it would be conceivable to provide two or more casting nozzles 6. These could be connected via appropriate lines to separate prepolymer and crosslinker containers in order to supply different polymers independently to the majority of the casting nozzles 6. The casting nozzles 6 could then be arranged at a distance from each other along the longitudinal axis of the press jacket 20 in order to produce several polymer layers 20.1, 20.2, 20.3 simultaneously in a single casting by simultaneously dispensing the polymer from the casting nozzles 6.

[0050] By means of such a continuous casting process, also known as rotational casting, an endless, self-contained cylindrical-tube-shaped press jacket 20 is gradually produced over the width of the winding mandrel 4, the inner circumference of which essentially corresponds to the outer circumference of the winding mandrel 4.

[0051] In principle, it would be conceivable to apply the source material 20‴ to more than one in Fig. 3 to wind the shown winding mandrel 4. For example, two winding mandrels could be provided, arranged parallel to each other with respect to their longitudinal axes and spaced apart. Alternatively, it would also be conceivable to apply the polymer to the radially inner surface of the winding mandrel 4, e.g., by centrifugal casting. Regardless of the embodiment described, the finished press jacket 20 is finally removed from the at least one winding mandrel 4.

[0052] Although this is not shown in the figures, the reinforcement structure 20" of the at least one polymer layer 20.1, 20.2 could also be composed of several starting materials 20‴ laid on top of each other in the radial direction, each running in the longitudinal axis direction and in the circumferential direction of the press jacket 20.

[0053] The formation of a corresponding polymer layer comprising or containing a thermoplastic elastomer in the form of a copolymer can be carried out analogously using such a device. The thermoplastic elastomer is applied over the circumference of the winding mandrel 4 if it is the radially innermost polymer layer of the press jacket. Alternatively or additionally, it can be applied to a polymer layer already produced from polyurethane to then form the radially outermost polymer layer of the press jacket. The thermoplastic elastomer according to the invention can, for example, be applied as a polymer layer by an extrusion process.

Claims

1. Press cover for a press apparatus for the treatment of a fibrous material web, comprising at least one polymer layer (20.1, 20.2, 20.3), the at least one polymer layer (20.1, 20.2, 20.3) being made of or comprising at least one thermoplastic elastomer in the form of a copolymer.

2. Press cover according to Claim 1, characterized in that the thermoplastic elastomer is a segmented block copolymer.

3. Press cover according to Claim 1 or 2, characterized in that the thermoplastic elastomer is a thermoplastic copolyester elastomer (COPE).

4. Press cover according to any of Claims 1 to 3, characterized in that the thermoplastic elastomer is a thermoplastic copolyamide elastomer (COPA).

5. Press cover according to any of Claims 1 to 4, characterized in that the at least one polymer layer (20.1, 20.2, 20.3) comprises an embedded reinforcing structure (20"), the reinforcing structure (20") comprising at least one reinforcing thread (21).

6. Press cover according to Claim 5, characterized in that the at least one reinforcing thread (21) is made of or comprises a polymer, the polymer selected being a polyester, polyethylene naphthalate or polyamide, such as aramid.

7. Press cover according to Claim 5 or 6, characterized in that one or more reinforcing threads (21) are provided as longitudinal threads (21.1) which, running in the longitudinal direction of the press cover (20), are arranged with distance and parallel to one another over the circumference of the press cover (20).

8. Press cover according to Claim 7, characterized in that at least one further reinforcing thread (21) is provided as a circumferential thread (21.2) which runs preferably within the polymer layer (20.1, 20.2, 20.3) in the form of a helical line in the circumferential direction of the press cover, and preferably the reinforcing threads (21) configured as longitudinal thread (21.1) and the at least one further reinforcing thread (21) configured as circumferential thread (21.2) form a scrim with one another, preferably such that the longitudinal threads (21.1) are arranged radially within the at least one circumferential thread (21.2) - as viewed in relation to the longitudinal axis (20') of the press cover.

9. Press cover according to any of the preceding claims, characterized in that a plurality of polymer layers are provided and the at least one polymer layer (20.1, 20.2, 20.3), viewed in relation to the longitudinal axis (20') of the press cover (20), is the radially inner or innermost polymer layer (20.1), and additionally a further polymer layer (20.2), radially outermost as viewed in relation to the longitudinal axis (20') of the press cover (20), is provided.

10. Press cover according to Claim 9, characterized in that exactly two polymer layers (20.1, 20.2) are provided and the radially inner polymer layer (20.2) is likewise the radially innermost polymer layer of the press cover (20) .

11. Press roll, such as shoe press roll (12), for a shoe press (10) for treating a fibrous material web (24), characterized in that the press roll has at least one press cover (20) according to any of the preceding claims.

12. Shoe press (10) for treating a fibrous material web (24), preferably a paper, cardboard, tissue or pulp web, comprising a press roll and an opposing roll (14), which together form or delimit a nip (22), the press roll comprising a circulating press cover, characterized in that the press cover (20) is configured according to any of Claims 1 to 10.

13. Use of a press cover (20) according to any of Claims 1 to 10 for a press, such as shoe press (10) for treating a fibrous material web (24), preferably a paper, cardboard, tissue or pulp web.

14. Use of a thermoplastic elastomer in the form of a copolymer, preferably a segmented block copolymer, which is preferably a thermoplastic copolyester elastomer (COPE) and / or a thermoplastic copolyamide elastomer (COPA), for at least one polymer layer (20.1, 20.2, 20.3) of a press cover for a shoe press (10) for treating a fibrous material web (24).

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