CN114450447A

CN114450447A - Press jacket, use thereof and use of a thermoplastic elastomer in the form of a copolymer in a polymer layer of a press jacket

Info

Publication number: CN114450447A
Application number: CN202080067629.1A
Authority: CN
Inventors: D.德尔马斯
Original assignee: Voith Patent GmbH
Current assignee: Voith Patent GmbH
Priority date: 2019-09-26
Filing date: 2020-07-20
Publication date: 2022-05-06
Also published as: DE102019125908A1; JP2022550082A; US20220372701A1; WO2021058165A1; EP4034706A1

Abstract

The invention relates to a press jacket 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. The invention also relates to the use of such a press jacket in a shoe press, to such a shoe press and to a press roll, each comprising such a press jacket. 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 jacket of a shoe press for treating a fibrous web.

Description

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

The invention relates to a press jacket, in particular according to the independent claims, in particular for a press for treating, for example smoothing or dewatering, a fibrous web. The invention also relates to a shoe press and a use of a press shoe in a shoe press and a machine comprising such a shoe press, in particular according to the side-by-side claims.

Pressing devices such as shoe presses have long been an integral part of modern paper machines. They are essentially composed of a fixedly arranged shoe (also called press shoe) extending in the cross-machine direction and a press jacket running around the fixed shoe. The press jacket is deformable and has a substantially tubular shape during operation. The shoe is shaped so that it constitutes a nip (press nip) with a mating roll. The nip is defined by the contact surfaces of the mating rolls in the shoe. The shoe is designed to be movable and movable toward the mating roll.

The press sleeves have extremely high requirements with regard to their stability, namely with regard to surface hardness, resistance to pressure, temperature and hydrolysis. Furthermore, press sleeves are subjected to strong bending alternating loads during operation. When entering at the edge of the shoe (before the nip, viewed in the direction of rotation of the press jacket), the bending is first carried out with a relatively small radius. The transition to the reverse bend occurs immediately after the nip. On leaving at the edge of the other shoe (i.e. after the nip, viewed in the direction of rotation of the press jacket), the bending is again performed in the opposite direction. This deformation of the press jacket on entry and exit is also referred to as an alternating nip. It is readily apparent that the press jacket has a very high tendency to break, especially at this location, because of the high mechanical stresses. Accordingly, a number of measures for increasing the stability of press sleeves are known from the prior art.

The press jacket must therefore be flexible enough so that it can be guided around the shoe, must be rigid enough so that it does not deform too much or compress too much under the press load in the press nip, and must moreover be sufficiently wear-resistant. The press jacket thus consists of a single-layer or multi-layer polymer layer, preferably made of polyurethane, in which reinforcing yarns in the form of a scrim (german: Gelege) or a fabric (german: Gewebe) can be embedded.

The invention relates to the subject matter mentioned at the beginning.

Despite the sufficient flexibility and at the same time sufficient rigidity of the press sleeves known from the prior art, their chemical resistance, in particular with respect to water and oil, their abrasion resistance, their resistance to crack formation and crack growth, and their expansion behavior need to be improved.

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

The object is achieved by the features of the independent claims. Particularly preferred and advantageous embodiments of the invention are given in the dependent claims.

The inventors have realized that the above technical problem is solved if a thermoplastic elastomer (TPE) in the form of a copolymer is used for the polymer layer of the press jacket.

Thermoplastic elastomers are materials with an elastic polymer chain incorporated in the thermoplastic material, as defined by the wikipedia article, edited last in 2019, 7, 22, 11: 13. they can be processed in a purely physical process combining high shear, thermal action and subsequent cooling. In contrast, conventional elastomers are chemically large network crosslinked steric network molecules. This crosslinking cannot be released without destroying the material. Although no chemical crosslinking, which is time-consuming and complex at temperature, is required, as is the case for elastomers, the components produced have the property of rubber elasticity due to their special molecular structure. The re-application of heat and shear forces in turn causes the material to melt and deform.

Copolymers in the sense of the present invention are polymers composed of two or more different types of monomer units. According to the Wikipedia article mentioned at the outset, thermoplastic elastomers are divided into copolymers and elastomer alloys. The copolymer may be used as a random copolymer or a block copolymer. The former consists of a crystalline (and thus physically crosslinked) main polymer, such as polyethylene, the degree of crystallinity of which is reduced by monomers, such as vinyl acetate, added randomly along the chain, so that the crystallites (hard phase) in the finished material (such as EVA) are no longer in direct contact. They then act as isolated crosslinking points, as in conventional elastomers. In block copolymers, hard and soft segments separate sharply in one molecule (e.g., SBS, SIS). Below a certain temperature in TPE, the material separates into a continuous phase and a discontinuous phase. As soon as the latter is below its glass transition temperature Tg (the Tg of the continuous phase is significantly below the later application temperature), it will act again as a crosslinking point. In contrast, elastomeric alloys are multicomponent mixtures, i.e. mixtures (hybrids) of finished polymers, so that plastics are composed of many types of molecules. By different mixing ratios and additives, customized materials can be obtained (e.g. polyolefin elastomers made of polypropylene (PP) and Natural Rubber (NR), which cover a wide hardness range, depending on the quantitative ratio).

Preferably, the thermoplastic elastomer is a segmented block copolymer. Such thermoplastic elastomers may be thermoplastic polyetherester block copolymers (COPE or TPE-E) and/or thermoplastic copolyamide elastomers (COPA or TPE-A). Both polymers can be used as a substitute for conventional polyurethanes or Thermoplastic Polyurethanes (TPU). The soft segment is formed from a polyol. For the hard segment of the COPE, polyesters, polybutylene terephthalate (polybutylene terephthalate), polyethylene terephthalate (polyethylene terephthalate), methyl terephthalate (methyl terephthalate), poly (butylene 2, 6-naphthalate), polybutylene-co-isophthalic acid (polybutylene-co-isophthalate), or aromatic polycarbonates may be used.

In principle, it is conceivable to use a mixed polyol, i.e. an elastomer alloy between the above-mentioned thermoplastic copolymer and a polyurethane-based thermoplastic elastomer (TPU), for at least one of the polymer layers of the press jacket.

According to the invention, something is made of a material means that the item is partly or completely made of such a material.

The press jacket or the at least one polymer layer can be made partially or completely of a polymer. As polymers, use may be made here of pourable, curable, preferably elastomeric polymers, such as polyurethanes. The polymer can thus be provided as a cast elastomer.

By polymer layer is meant a layer comprising or entirely made of a pourable, hardenable, preferably elastomeric, polymer. Preferably, the polymer layer may be a hardened layer integrally formed by molding. In other words, it is integrally formed, i.e. made by e.g. casting. The term "monolithic" also includes the case where one layer is again made of multiple sheets of the same material as the polymer is cast. However, this is only to the extent that the sheets are substantially no longer visible after hardening, but rather a single, preferably uniform layer is produced. The same applies to the press jacket produced.

In the case of the provision of a plurality of polymer layers, these can be arranged at least partially one above the other, viewed in the radial direction, over the width of the press jacket. At least a partial section over the width of the press jacket means that the press jacket is constructed, for example, at its axial ends, as a single layer only, along the longitudinal axis of the press jacket, but rather as a double or multiple layer between the axial ends. However, the polymer layer can also extend over the entire width of the press jacket. The thickness of the press jacket, and thus also the thickness of the individual polymer layers, can vary along the longitudinal axis in partial sections in a section through its longitudinal axis. Thus, for example, the radially outermost polymer layer can be less in the region of the width edges of the press jacket than in the middle of the press jacket. In other words, in the region of the width edge, the radially outermost polymer layer may be of smaller thickness than the radially inner or radially innermost polymer layer. It is preferred to provide only one, two or three polymer layers. They can be of identical design in terms of their polymers or differ in terms of their hardness or the stoichiometry of the prepolymer. The total thickness of the press jacket produced, measured in the radial direction in a section through its longitudinal axis, may be 5mm to 10mm, preferably 5mm to 7mm, particularly preferably 5mm to 6 mm. According to the invention, in the case of the provision of only one layer, the press jacket can be produced from only one casting part, i.e. in one piece, so that the only layer has the thickness just mentioned.

In the context of the present invention, a press jacket is produced in which at least one polymer layer has hardened and, if appropriate, finished, and can be used, for example, for the purposes mentioned at the outset in shoe presses. Similarly, a manufactured polymer layer refers to a layer that has been hardened.

Within the scope of the present invention, a reinforcing yarn is understood to be a soft, woven, linear fabric having a predominant or predominant extent and consistency in its longitudinal direction. The fibers are fibers in the form of single, endless or continuous filaments. In contrast, within the scope of the invention, a fiber bundle is not a monofilament but is a single wire per se, for example a twisted or twisted wire, i.e. a bundle of continuous fibers or monofilaments. The fiber bundle itself can be made entirely of fibers twisted around one another.

At least the longitudinal yarns as a representation of the production of the reinforcement yarn according to the invention means that only the longitudinal yarns are so designed or that additionally the longitudinal yarns and at least one further circumferential yarn are so produced. If, for example, a scrim consisting of circumferential yarns and longitudinal yarns is preferably present, it is to say that at least the longitudinal yarns are designed according to the invention.

In the context of the present invention, the term "reinforcing structure" means the reinforcement of at least one layer comprising or consisting of a polymer, i.e. the reinforcement of a polymer layer. The reinforcing structure can be completely embedded in the polymer layer, so that the reinforcing structure does not extend beyond the boundary of the polymer layer. In other words, the polymer layer assumes the function of a matrix which surrounds the reinforcing structure and is bonded to the matrix by adhesion or cohesion. Such a reinforcing structure may comprise a linear fabric, such as a twisted or twined thread, and/or a flat fabric, such as a woven, knitted, interwoven or scrims, and may be made from a corresponding starting material, for example by winding. In other words, the individual reinforcement yarns according to the invention are themselves linear fabrics. A plurality of such reinforcing threads can be designed, for example, as longitudinal threads and/or circumferential threads, so that they together form a flat fabric. The at least one reinforcing yarn embedded in the at least one polymer layer is the reinforcing structure of the press jacket or its polymer layer.

The term "starting material" refers to the material or semi-finished product, here the at least one reinforcing yarn, from which the reinforcing structure of the press jacket manufactured according to the invention is manufactured.

The reinforcing yarns or reinforcing structures may be made of or comprise a polymer. Suitable polymers are polyesters, polyethylene naphthalates or polyamides such as aramids. The material of the at least one polymer layer is thereby distinguished from the material of the at least one reinforcing yarn or reinforcing structure embedded therein.

In the context of the present invention, a press device is understood to mean, for example, a shoe press, which is used, for example, for dewatering or treating, for example, smoothing, a fibrous web. The shoe press includes a shoe press roll and a mating roll that together form or bound the nip. The shoe press roll also comprises a press jacket running around and a fixed press element, a so-called press shoe. The press shoe is supported, for example, by means of a hydraulic press element on a supporting, likewise fixed yoke and presses against a revolving press jacket. The press jacket encircles with respect to the stationary press shoe and the yoke and thereby presses against the mating roll in the nip. The press shoe and the yoke are arranged radially inside the press jacket. The term "fixed" is understood to mean that the press element does not run around relative to the shoe press roll or the counter roll, but rather is moved translationally, preferably in its radial direction, towards and away from the counter roll and can thus be moved relative to the counter roll. In addition to the fibrous web and the press jacket, one or more press felts running continuously in the circumferential direction and/or further press belts running endlessly can be guided through the press nip of the shoe press. Such a shoe press may of course also comprise more than one nip.

In the context of the present invention, the term "fibrous web" is understood to mean a scrim or entanglement of fibers, for example wood fibers, plastic fibers, glass fibers, carbon fibers, additives or the like. The fibrous web can thus be configured, for example, as a paper, cardboard or tissue web. It may essentially comprise wood fibres, wherein small amounts of other fibres or even additives and additives may be present. This can be determined by the skilled person depending on the application.

The advantages according to the invention are achieved particularly well if a plurality of reinforcing threads are preferably used as longitudinal threads and at least one reinforcing thread is used as a circumferential thread which circumferentially surrounds the longitudinal threads, and is embedded in the polymer layer as a scrim. Since the scrim can particularly well withstand locally excessive loads.

The advantages according to the invention are achieved particularly well if the press jacket is formed from preferably a plurality of polymer layers arranged radially one above the other. If two polymer layers are provided, the radially inner polymer layer is provided with a reinforcing structure according to the invention. This means that the reinforcing structure is arranged only in the radially innermost polymer layer. If three or more polymer layers are provided, the reinforcing structure is preferably arranged in the second lowest polymer layer, i.e. in the polymer layer radially above the radially innermost polymer layer.

The invention further relates to a press roll, for example a shoe press, for a shoe press for treating a fibrous web, characterized in that the press roll has at least one press jacket according to one of the preceding claims.

The invention also relates to a shoe press for treating a fibrous web, preferably a paper, cardboard, paper towel or pulp web, comprising a press roll and a counter roll which together form a nip or delimit a nip, wherein the press roll comprises a press jacket running around it, characterized in that the press jacket is constructed according to the invention.

The invention also relates to the use of a press jacket according to the invention in a press, such as a shoe press for treating a fibrous web, preferably a paper, cardboard, tissue or pulp web.

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

The invention is further elucidated below without limiting the generality with reference to the accompanying drawings. In the drawings:

fig. 1 shows a schematic side view, partly in section, of a shoe press with a press jacket according to an embodiment of the invention.

Fig. 2a and 2b each show an embodiment of a press jacket in a section through its longitudinal axis;

fig. 3 shows a schematic representation of an apparatus for producing a press jacket in a side view.

In fig. 1 a schematic side view is shown in partial cross-section of a shoe press 10, which here comprises a press roll according to the invention, such as a shoe press roll 12, and a counter roll 14. The shoe press roll 12 and the mating roll 14 are arranged parallel to each other with respect to their longitudinal axes. Which together constitute the nip 22 or define the boundaries of the nip.

The mating roll 14 is here constituted by a cylindrically designed roll rotating about its longitudinal axis, while the shoe press roll 12 is constituted by a shoe 16, a fixed yoke 18 supporting the shoe 16 and a press jacket 20. The shoe 16 and yoke 18 are fixedly disposed relative to the mating roll 14 or press jacket 20. Meaning that they do not rotate. The shoe 16 is supported by a yoke 18 and is pressed by a hydraulic press element, not shown, against the radially innermost surface of a press jacket 20 running around it. The press jacket 20 circumferentially surrounds the shoe 16 and yoke 18 and rotates therein about the longitudinal axis of the press jacket in a direction opposite to the direction of rotation of the mating roll 14. Due to the concave design of the shoe 16 on its side facing the mating roll 14, a relatively long nip 22 is formed.

The shoe press 10 is particularly suitable for dewatering a fibrous web 24. During operation of the shoe press, the fibrous web 24 is guided through the press nip 22 together with one or two press felts 26, 26'. In this case exactly two press felts 26, 26' sandwich the fibrous web 24 between them. Pressure is applied indirectly to fibrous web 24 in nip 22 by press felts 26, 26' as it passes through nip 22. This is due to the fact that the radially outermost surface of mating roll 14 and the radially outermost surface of press jacket 20 are in direct contact with the respective press felts 26, 26' on the one hand. The liquid drained from the fibrous web 24 is mainly contained by one or two press felts 26, 26' and possibly grooves (not shown) provided in the surface of the press jacket. After leaving the press jacket 22, the liquid contained by the grooves of the press jacket 20 is thrown away before the press jacket 20 re-enters the press nip 22. Furthermore, the water contained by the press felts 26, 26' may be removed by the suction elements after leaving the press gap 22.

In other embodiments of the invention, not shown in the figures, press felts 26, 26' may be omitted. In this case, the fibrous web 24 is in direct contact with the press jacket 20 on the one hand and the counter roll 14 on the other hand, which together form a nip. The counter roller 14 can then be designed as a heated drying cylinder.

The press jacket shown in fig. 1 can be designed according to the invention as shown in the following figures.

In fig. 2a and 2b, various embodiments of the invention are shown in a cross-section, not to scale, partially shown, through the longitudinal axis 20' of the manufactured press jacket 20. The distance of the longitudinal axis 20' from the radially innermost surface of the respective polymer layer of the press sleeve 20 is also not shown to scale.

According to fig. 2a, exactly two polymer layers, namely a first polymer layer 20.1 and a second polymer layer 20.2, are provided. In the present case, the first polymer layer 20.1 is at the same time also the radially outermost polymer layer of the press jacket 20. The second polymer layer 20.2, in contrast, is at the same time the radially innermost polymer layer of the press jacket 20.

As shown, a reinforcing structure 20 "may be provided in the second polymer layer 20.2. Here, it is completely embedded in the polymer layer 20.2. This is indicated by the shaded circles, which may be a flat fabric such as a fiber or a linear fabric. This means that the reinforcing structure 20 "does not extend beyond the boundary of the polymer layer 20.2.

Here, the reinforcing structure 20 "comprises a plurality of reinforcing yarns 21 serving as longitudinal yarns 21.1. They are arranged spaced apart from one another and extend parallel to one another on their circumference in the longitudinal direction of the press jacket 20.

At least one further reinforcing thread 21 is additionally provided as a circumferential thread 21.2, which preferably runs helically in the circumferential direction of the press jacket within the same polymer layer 20.1, 20.2, 20.3, in which the longitudinal thread 21.1 is also arranged. The longitudinal yarns 21.1 and the circumferential yarns 21.2 form a scrim structure with respect to one another, i.e. the longitudinal yarns 21.1 are arranged radially inside at least one circumferential yarn 21.2, viewed in relation to the longitudinal axis 20' of the press jacket 20.

Fig. 2b shows a three-layer press jacket in a variant design with respect to fig. 2 a. It comprises here a radially outermost first polymer layer 20.1, a radially innermost third polymer layer 20.3 and a second polymer layer 20.2 arranged in sandwich manner between the two. This arrangement involves looking in its radial direction from the longitudinal axis 20' of the press jacket 20, as shown in the view of fig. 2 a. In this case, only the second polymer layer 20.2 is provided with (single) reinforcing structures 20 ″. This may of course also be different, so that alternatively or additionally such a reinforcing structure 20 "may also be arranged in the first polymer layer 20.1 and/or the third polymer layer 20.3.

In this case, one of the polymer layers 20.1, 20.2 or 20.3 shown in fig. 2a and 2b can be made of or comprise a thermoplastic elastomer in the form of a copolymer according to the invention. This is the case, for example, for the radially innermost and/or the radially outermost polymer layers. The remaining polymer layer may be made of polyurethane. This is obtained, for example, from a prepolymer and a crosslinking agent. The corresponding prepolymers are themselves obtained by reaction of isocyanates with polyols.

Fig. 3 shows a very schematic side view of an apparatus for producing a press jacket 20 according to the invention. The device has exactly one cylindrical winding mandrel 4, wherein the starting material 20' "is applied, for example, in a spiral shape, on its radially outermost circumferential surface. The starting material 20' ″ after embedding in the polymer constitutes the reinforcing structure 20 ″ of the press jacket 20 produced according to the invention.

The figure shows an initial stage of the manufacturing process. In this case, the end of the starting material 20' ″ is fixed to the polymer arranged on the outer circumference of the winding mandrel 4 for this purpose. In addition to the schematic illustration shown, the end of the starting material 20 '″ can also be laid directly, i.e., straight or applied to the winding mandrel 4, initially without a polymer being arranged between the starting material 20' ″ and the winding mandrel 4. The starting material 20' ″ may be a flat fabric or a linear fabric.

The winding mandrel 4 is rotatably mounted about its longitudinal axis 20 ', the longitudinal axis 20' corresponding to the longitudinal axis of the press jacket to be produced. The longitudinal axis 20' extends here perpendicularly into the paper. The casting compound, for example a castable, hardenable elastomer polymer, for example polyurethane, is fed through a pipe 5 from above through a casting nozzle 6 onto the radially outermost circumferential surface of the winding mandrel 4 or onto the starting material 20' ″. The casting material is selected, for example, in terms of its pot life and viscosity, such that it does not drip off the winding mandrel 4 during casting. During this, the winding mandrel 4 is rotated about its longitudinal axis in the direction of the arrow. Simultaneously with this rotation, the pouring nozzle 6 is guided along the winding mandrel 4 by suitable guide means, not shown in detail in fig. 3, parallel to the longitudinal axis 20' on the winding mandrel 4. At the same time as the casting material is being cast, the starting material 20' ″ is unwound or unwound and wound onto the rotating winding mandrel 4. In this case, the casting compound can be passed through the starting material 20' ″ until it reaches the winding mandrel 4. In this example, after the hardening step, the polymer constitutes the radially innermost, preferably elastomeric, polymer layer, which corresponds to the polymer layer 20.2 of the press jacket of fig. 2a, only a part of which is shown in fig. 3.

The casting compound emerging from the casting nozzle 6 is a mixture of prepolymer and crosslinking agent. The prepolymer is supplied from a prepolymer container, not shown, in which the prepolymer is stored or stirred. The prepolymer is the reaction product of an isocyanate and a polyol. The prepolymer can be present in the prepolymer container, for example, in the form of a prepolymer composed of the above-mentioned materials.

The crosslinking agent may be provided in a crosslinking agent container.

The prepolymer container and the crosslinking agent container are associated with an apparatus for producing the press jacket 20. They are connected in a fluid-conducting manner via a line, also not shown, to a mixing chamber (not shown) arranged upstream of the pouring nozzle 6 in the flow direction. The prepolymer-crosslinker mixture is thus produced upstream of the pouring nozzle 6 and externally, i.e. mixed in a mixing chamber. Independently of the production of the mixture, this mixture is then applied to the surface of the winding mandrel 4 in order to form at least one polymer layer of the press jacket 20.

In principle, it is conceivable to provide two or more pouring nozzles 6. They can be connected to the individual prepolymer containers and crosslinker containers by corresponding lines in order to feed even different polymers independently of one another to a plurality of pouring nozzles 6. The casting nozzles 6 can be arranged at a distance from one another along the longitudinal axis of the press jacket 20, so that a plurality of polymer layers 20.1, 20.2, 20.3 are simultaneously applied by means of the polymer from the casting nozzles 6 to form a casting.

By means of this continuous casting process, which is also referred to as spin casting, a continuous cylindrical tubular press jacket 20 is gradually produced over the width of the winding mandrel 4, which is closed on itself about its longitudinal axis 20', the inner circumference of which essentially coincides with the outer circumference of the winding mandrel 4.

It is basically conceivable that the starting material 20' ″ is wound onto more winding mandrels than the one winding mandrel 4 shown in fig. 3. For example, two winding mandrels can be provided, which can be arranged at a parallel distance from their longitudinal axis. Alternatively, it is also conceivable for the polymer to be applied to the radially inner circumferential surface of the winding mandrel 4, for example, in a centrifugal manner. Regardless of the embodiment described, the finished press jacket 20 is finally removed from the at least one winding mandrel 4.

Although not shown in the figures, the reinforcing structure 20 ″ of the at least one polymer layer 20.1, 20.2 can also be formed from a plurality of starting materials 20' ″ arranged radially one above the other and extending in the longitudinal direction and in the circumferential direction of the press jacket 20, respectively.

Structures comprising or containing respective polymer layers of thermoplastic elastomers in the form of copolymers can be similarly made by such devices. If the thermoplastic elastomer is the radially innermost polymer layer of the press jacket, it is applied to the circumference of the winding mandrel 4. Alternatively or additionally, it can also be applied to a polymer layer which has been produced from polyurethane, in order then to form the radially outermost polymer layer of the press jacket. The thermoplastic elastomer according to the invention can be applied as a polymer layer, for example by an extrusion process.

Claims

1. A press jacket comprising at least one polymer layer (20.1, 20.2, 20.3), wherein the at least one polymer layer (20.1, 20.2, 20.3) comprises or is made of at least one thermoplastic elastomer in copolymer form.

2. The press jacket according to claim 1, wherein said thermoplastic elastomer is a segmented block copolymer.

3. A press jacket as set forth in claim 1 or 2, characterized in that said thermoplastic elastomer is a thermoplastic copolyester elastomer (COPE).

4. A press jacket according to any of the claims 1 to 3, characterised in that said thermoplastic elastomer is a thermoplastic copolyamide elastomer (COPA).

5. Press jacket according to one of the claims 1 to 4, characterized in that a reinforcing structure (20 ") is embedded in the at least one polymer layer (20.1, 20.2, 20.3), wherein the reinforcing structure (20") comprises at least one reinforcing yarn (21).

6. Press jacket according to claim 1 or 5, characterized in that a plurality of polymer layers (20.1, 20.2, 20.3) are provided and that said at least one polymer layer is the radially inner or innermost polymer layer (20.1) viewed in relation to the longitudinal axis (20 ') of the press jacket (20) and that a further, radially outermost polymer layer (20.2) viewed in relation to the longitudinal axis (20') of the press jacket (20) is additionally provided.

7. Press jacket according to claim 6, characterized in that exactly two polymer layers (20.1, 20.2) are provided and that the radially inner polymer layer (20.2) is at the same time also the radially innermost polymer layer of the press jacket (20).

8. Press jacket according to one of the claims 1 to 7, characterized in that the at least one reinforcing yarn (21) is made of or comprises a polymer, wherein polyester, polyethylene naphthalate or polyamide, such as aramid, is selected as polymer.

9. Press jacket according to one of the claims 1 to 8, characterised in that one or more reinforcing yarns (21) are provided as longitudinal yarns (21.1) which are arranged parallel to one another at a distance on the circumference of the press jacket (20) extending in the longitudinal direction of the press jacket (20).

10. Press jacket according to one of claims 1 to 9, characterised in that the at least one further reinforcing yarn (21) is provided as a circumferential yarn (21.2) which extends preferably in a spiral-like manner in the polymer layer (20.1, 20.2, 20.3) in the circumferential direction of the press jacket, and that the reinforcing yarn (21) which is preferably designed as a longitudinal yarn (21.1) and the at least one further reinforcing yarn (21) which is designed as a circumferential yarn (21.2) form a loose plain weave with one another, preferably such that the longitudinal yarn (21.1) is arranged radially inside the at least one circumferential yarn (21.2) viewed in relation to the longitudinal axis (20') of the press jacket.

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

12. Shoe press (10) for treating a fibrous web (24), preferably a paper, cardboard, paper towel or pulp web, the shoe press (10) comprising a press roll and a counter roll (14) which together form a nip or a boundary limiting the nip, wherein the press roll comprises a press jacket running around it, characterized in that the press jacket (20) is constructed according to one of claims 1 to 10.

13. Use of a press jacket (20) according to one of claims 1 to 10 in a press, such as a shoe press (10) for treating a fibrous web (24), preferably a paper, board, tissue or pulp web.

14. Use of a thermoplastic elastomer in at least one polymer layer (20.1, 20.2, 20.3) of a press jacket for a shoe press (10) for treating a fibrous web (24), said thermoplastic elastomer being 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).