Compression sleeve having reinforcing yarns designed as twisted yarns

Abstract

The present invention relates to a pressure sleeve (200) comprising at least one polymer layer (240) in which a reinforcing structure (100) is embedded, wherein the reinforcing structure (100) is designed as a yarn layer comprising a first layer radially inward and a second layer radially outward, the first layer comprising a plurality of longitudinal yarns (220) extending axially along the pressure sleeve (200), and the second layer comprising at least one circumferential yarn (230) extending substantially circumferentially along the pressure sleeve (200), wherein the longitudinal yarns (220) of the first layer and preferably the at least one circumferential yarn of the second layer (230) are designed as reinforcing yarns (10), which are designed as twisted yarns by first twisting multiple single fibers or fiber bundles (30) together along a first twist direction and at a first twist rate to form a primary twisted strand (20), and then twisting multiple such primary twisted strands (20) together along a second twist direction opposite to the first twist direction and at a second twist rate, wherein the first twist rate is less than the second twist rate, and when viewed radially along the pressure sleeve (200), the longitudinal yarns (220) and the at least one circumferential yarn (230) are arranged to contact each other. The invention also relates to a pressure roller and a shoe press having such a pressure sleeve (200) for processing fiber webs, and the application of such a pressure sleeve (200) in presses for processing fiber webs, especially paper webs, paperboard webs or tissue webs, especially shoe presses.

Description

[0001] This invention relates to a press sleeve comprising at least one polymer layer in which a reinforcing structure is embedded, wherein the reinforcing structure is designed as a yarn layer comprising a first layer radially inward and a second layer radially outward. The first layer consists of a plurality of longitudinal yarns extending axially along the press sleeve, and the second layer consists of at least one circumferential yarn extending substantially circumferentially along the press sleeve. The longitudinal yarns of the first layer and preferably the at least one circumferential yarn of the second layer are respectively designed as reinforcing yarns, which are designed as twisted yarns by first twisting a plurality of individual fibers or fiber bundles together along a first twist direction and at a first twist rate to form initial twisted strands, and then twisting a plurality of such initial twisted strands together along a second twist direction opposite to the first twist direction and at a second twist rate. The invention also relates to a press roll and shoe press having such a press sleeve for processing fiber webs, and the application of such a press sleeve in presses, especially shoe presses, for processing fiber webs, particularly paper webs, paperboard webs, or tissue webs.

[0002] The inventors described such a pressure sleeve in document DE 10 2019 126 077 A1, the disclosure of which is therefore incorporated herein in its entirety. The inventors have recognized that using specially twisted yarns as reinforcing yarns has a beneficial effect on the pressure sleeve because the risk of failure due to (typically only localized) overload in the pressure gap is reduced. In other words, reinforcing yarns designed as twisted yarns can help extend the service life of the pressure sleeve.

[0003] However, when the radially inner longitudinal yarns are arranged in contact with at least one radially outer circumferential yarn when viewed radially from the presser sleeve, there remains a risk that the radially inner longitudinal yarns may fail during the wet covering process (Batzendurchgang). Simulation results by the inventors indicate that the failure is caused by significant stress concentration, which occurs when at least one circumferential yarn directly presses against the longitudinal yarn during the wet covering process. This stress concentration is localized at the intersection of the longitudinal yarn and the at least one circumferential yarn on the longitudinal yarn. Therefore, in the case of the presser sleeve described in the aforementioned document DE 10 2019 126 077 A1, the longitudinal yarns and at least one circumferential yarn are intentionally arranged not to contact each other. This prevents direct force transmission between these yarns, and the matrix material, such as polyurethane, placed between them can act as a damping agent. However, a disadvantage of this approach is that the relatively spaced arrangement of the longitudinal yarns and at least one circumferential yarn is relatively costly in terms of manufacturing technology.

[0004] Therefore, there is still a need for improvement. The technical problem this invention aims to solve is to investigate further measures to make the pressure sleeve more resistant to overload conditions, such as the so-called wet material covering process, thereby further improving the service life of the pressure sleeve. At the same time, production costs should be kept as low as possible.

[0005] The technical problem is solved by the independent claims, wherein the technical solutions of the dependent claims are advantageous extensions of the invention.

[0006] Specifically, after in-depth analysis of the causes and numerous experiments, the inventors were pleasantly surprised to find that the aforementioned technical problem could be solved by selecting a first twist rate that is less than the second twist rate in the aforementioned type of press sleeve. Simultaneously, when viewed radially along the press sleeve, the longitudinal yarns and the at least one circumferential yarn are arranged in contact with each other, thereby maintaining lower production costs.

[0007] The choice of twist rate for twisted yarns is highly unusual. Those skilled in the art of textiles, particularly in the field of yarns, know that the characteristic properties of twisted yarns depend less on the twist rate, i.e., the number of twists per meter of yarn (or the number of turns), and more on the twist angle (also called the "twist angle") of the individual strands used to create the twisted yarn. This twist angle, in turn, depends to a large extent on the diameter of the twisted yarn. The relationship between the twisted yarn diameter and the twist angle is illustrated in... Figure 1 As shown, where d is the diameter of the twisted yarn, l is the length of the twisted yarn for a complete twist of one strand, and θ is the twist angle. The following formula applies here:

[0008]

[0009] This shows that the larger the diameter of the twisted yarn, the larger the twist angle. Furthermore, as previously known, the characteristic properties of twisted yarns depend on the twist angle. For example, it is generally accepted that the twist increases with increasing twist angle.

[0010] It is generally desirable to keep the twist of twisted yarns low, as this would cause them to curl. Therefore, in two-stage twisting yarn production—that is, the process of making twisted yarn from initial twisted ply yarns—the twisting directions are always opposite. For example, the initial twisted ply yarns can be twisted along the S direction, while the final twisted yarn made from multiple initial twisted ply yarns can be twisted along the Z direction, as exemplarily shown in… Figure 2As shown in the diagram. Since the diameter of the initial twisted ply is naturally much smaller than the diameter of the final twisted yarn made from it, the twist rate of the initial twisted ply must be significantly higher than that of the final twisted yarn. Only in this way can the initial twisted ply achieve a similar or identical twist angle, thereby obtaining similar or identical characteristic performance properties. This can especially compensate for the twist gained by the final twisted yarn in the second twisting stage by twisting the initial twisted ply. As a result, even without pretension, the final twisted yarn can lie straight on a flat pad without any tendency to curl. Therefore, in two-stage twisting yarns, the first twist rate is almost always chosen to be higher than the second twist rate.

[0011] In the field of automobile tire manufacturing, there are already reinforcing yarns composed of untwisted ply yarns with a first twist rate that is less than the twist rate of a final twisted yarn composed of multiple untwisted ply yarns. For example, see Bridgestone's document US 4,787,200 A. However, since the reinforcing structure in an automobile tire is fundamentally different from the reinforcing structure in the aforementioned bushing, the same problems do not occur, especially the problem of localized over-tension at the intersection of the longitudinal and circumferential yarns. In automobile tires, there are generally no longitudinal yarns that contact at least one circumferential yarn radially outward. The specific problems to be solved here are different in nature, even though these problems ultimately lead to a longer service life for automobile tires. Therefore, those skilled in the art have no incentive to seek prior art from a completely different technical field.

[0012] This also applies to the technical field of toothed belt manufacturing, as described in Nippon's document EP 3 770 309A1.

[0013] For technicians in the field of press sleeve manufacturing, there are at least no obvious prompts for them to choose or specially produce twisted reinforcing yarns that deviate from the usual basic principles.

[0014] Therefore, the inventors' contribution lies in recognizing that, for twisted reinforcing yarns, it is advantageous to select a first twist rate that is less than a second twist rate in terms of the pressure sleeve's resistance to overload. The tendency of the reinforcing yarn to curl can be resisted by a corresponding pretension, with which the reinforcing yarn is embedded in the polymer matrix.

[0015] Figure 3 The experimental apparatus for determining the radial stiffness of a reinforcing yarn designed as a twisted yarn is schematically shown. The greater the radial deformation L of the reinforcing yarn under a preset force (9.8 N in this case), the softer the reinforcing yarn is in its radial direction.

[0016] The inventors have recognized that twisted yarns with a first twist rate selected to be less than the second twist rate exhibit significantly softer radially at lower pretension than the same twisted yarns at higher pretension. This difference in stiffness is much greater than in conventionally used twisted yarns, where the first twist rate is greater than the second twist rate. This property can be advantageously utilized in press sleeves. In a press sleeve, the reinforcing yarns arranged radially more inner, particularly the longitudinal yarns forming the first fabric layer extending axially along the press sleeve, are provided with greater pretension compared to at least one reinforcing yarn arranged radially more outer, particularly at least one circumferentially extending yarn. Therefore, when using the same twisted yarn material, it is possible to achieve at least one reinforcing yarn arranged radially more outer than the reinforcing yarn arranged radially more inner.

[0017] This is advantageous because the relatively soft design of at least one radially outer reinforcing yarn reduces the risk of cracks initiating on the outer surface of the pressure sleeve under overload conditions. The inventors have observed that such cracks typically begin at the bottom of grooves usually formed on the outer surface of the pressure sleeve. However, if at least one radially outer reinforcing yarn is designed to be relatively soft, the stress peaks in the polymer material of the pressure sleeve, particularly at the bottom of the grooves, can be reduced.

[0018] It is also recognized that it is advantageous to design the radially inner reinforcing yarns as stiff as possible. That is, these yarns tend to be the first to break during wet covering, and this risk can be mitigated if these yarns are designed to be correspondingly stiff.

[0019] It has been proven advantageous in experiments that the first twist rate is equivalent to 70% to 90% of the second twist rate, wherein the first twist rate is preferably between 70 and 90 revolutions per meter, more preferably between 75 and 85 revolutions per meter, and even more preferably between 80 revolutions per meter.

[0020] Similar to the usual case in sewing thread, the first twist direction can be the S direction, and the second twist direction can be the Z direction. Figure 2 This typical sewing thread is shown as an example.

[0021] and Figure 2 Unlike typical sewing threads, the reinforcing yarn according to the invention preferably consists of two single fibers or fiber bundles per initial twist, and the resulting twisted yarn consists of three initial twists. This results in a particularly stable reinforcing yarn. The reinforcing yarn should also be able to withstand tension along its longitudinal direction.

[0022] As described above, a significant advantage in manufacturing technology is that the reinforcing structure according to the invention is designed as a yarn layer comprising a first layer and a second layer. The first layer consists of a plurality of longitudinal yarns extending axially along the pressure sleeve, and the second layer consists of at least one circumferential yarn extending substantially circumferentially along the pressure sleeve, wherein, viewed radially along the pressure sleeve, the longitudinal yarns and the at least one circumferential yarn are arranged relative to each other in contact. "Substantially circumferentially" can be understood in particular as the at least one circumferential yarn extending helically around the longitudinal axis of the pressure sleeve. More than one circumferential yarn may also be included in the second layer, and these circumferential yarns may be arranged relative to each other in a manner similar to that of a threaded component with multiple pitches. Preferably, the longitudinal yarns of the first layer and / or at least one circumferential yarn of the second layer correspond to the at least one reinforcing yarn designed as a twisted yarn.

[0023] In an extended design of this concept, it is proposed that, within the compression fitting, the longitudinal yarns of the first layer have a first pretension, while at least one circumferential yarn of the second layer has a second pretension, wherein the first pretension is greater than the second pretension, and preferably, the first pretension is equivalent to at least 7 times and / or at most 13 times the second pretension. Thus, even using the same yarn material in both layers, the aforementioned advantageous difference in stiffness of the reinforcing yarns in the two layers can be achieved.

[0024] It is sufficient for the entire reinforcing structure of the pressure sleeve to consist of only the first and second layers.

[0025] Furthermore, it has proven advantageous that at least one reinforcing yarn designed as a twisted yarn has a coating. This coating can support the bonding of the twisted yarn to its surrounding polymer matrix.

[0026] Advantageously, at least one reinforcing yarn designed as a twisted yarn has a fineness between 800 dtex and 1500 dtex, preferably between 1000 dtex and 1200 dtex, and more preferably 1100 dtex. The unit dtex is an abbreviation for decitex, which stands for 1 / 10 tex. The formal tex system represents linear density, i.e., the fineness of the yarn. Fineness is defined by the weight of a given length of yarn. tex indicates how many grams 1 km of yarn weighs (e.g., 1 dtex = 1 / 10 tex: 1 km of yarn weighs 10 grams). If the reinforcing yarn is too fine, it cannot absorb the tension in the compression fitting at the required scale. If the reinforcing yarn is too thick, it leads to problems with bonding to the polymer matrix.

[0027] It has proven advantageous that the initial twisted strands are composed of multiple fiber bundles, each fiber bundle having 180 to 230 monofilaments.

[0028] Preferably, all the yarns of the reinforcing structure of the pressure sleeve are consistent with at least one reinforcing yarn designed as a twisted yarn. This applies particularly to the first and second twist rates.

[0029] It is particularly preferred that all the yarns of the reinforcing structure of the bladder are constructed identically. This allows for the purchase and use of large quantities of the same yarn material, thereby keeping the manufacturing cost of the bladder low.

[0030] Another aspect of the invention relates to a pressure roller for a boot press for processing fiber webs, wherein the pressure roller has at least one of the aforementioned pressure sleeves according to the invention.

[0031] Another aspect of the invention relates to a shoe press for processing fiber webs, particularly paper webs, paperboard webs, or tissue webs, the shoe press comprising a pressure roll and a mating roll that together form or define an elongated pressure gap, wherein the pressure roll includes a surrounding pressure sleeve constructed according to the invention.

[0032] The present invention also relates to the application of the aforementioned pressure sleeve according to the invention in a press, particularly a shoe press, for processing fiber webs, particularly paper webs, paperboard webs or tissue webs.

[0033] The invention is explained below with the aid of illustrative and non-to-scale drawings. In the drawings:

[0034] Figure 1 A schematic diagram illustrating the general relationship between the diameter of twisted yarn and the twist angle is shown.

[0035] Figure 2 An example of a typical twisted yarn, such as sewing thread, is shown, in which three initial twisted strands twisted in the S direction twisted together in the Z direction;

[0036] Figure 3 A schematic diagram illustrating the principle of how the radial stiffness of reinforcing yarn can be determined is shown.

[0037] Figure 4 The comparison of radial stiffness of different reinforcing yarns under different pretensions is shown;

[0038] Figure 5 The reinforcing yarn for the pressure sleeve according to the invention is shown;

[0039] Figure 6 A boot press with a pressure sleeve according to the invention is shown; and

[0040] Figure 7 A schematic diagram illustrating the manufacturing method of the pressure sleeve according to the present invention is shown.

[0041] Figure 5An exemplary illustration shows a reinforcing yarn 10, designed according to the invention, so as to be mounted as part of a reinforcing structure 100 in a pressure sleeve 200 according to the invention (see [reference]). Figure 6 The reinforcing yarn 10 is designed as a twisted yarn, wherein two fiber bundles 30 are first twisted together in the S-twist direction to form a primary twisted ply 20, and then three such identically manufactured primary twisted ply 20s are twisted together in the Z-direction at a second twist rate to form the final twisted yarn or reinforcing yarn 10. The reinforcing yarn 10 can then be coated.

[0042] According to the present invention, the first twist rate is less than the second twist rate. In this embodiment, the first twist rate is 80 revolutions per meter, and the second twist rate is 100 revolutions per meter. Furthermore, the yarn has a fineness of 1100 dtex. Therefore, the reinforcing yarn 10 according to the present invention can be characterized by the following shorthand notation:

[0043] dtex1100 x 2x 3S80 / Z100.

[0044] At this point, the embodiment referred to below as AB-1, for the reinforcing yarn 10 used in the pressure sleeve according to the invention, conforms to the above-mentioned requirements regarding its radial hardness. Figure 3 The test apparatus was investigated and compared with two embodiments, AB-2 and AB-3, of corresponding reinforcing yarns in the prior art. Although the reinforcing yarns according to AB-2 and AB-3 have the same characteristics as those in embodiment AB-1 (e.g., ... Figure 5 The basic structure is shown, but in the case of these reinforcing yarns, the first twist rate is greater than the second twist rate. According to AB-2 reinforcing yarns, they can be characterized using the following shorthand notation:

[0045] dtex1100 x 2x 3S165 / Z150.

[0046] Furthermore, AB-3 reinforced yarn can be characterized using the following shorthand notation:

[0047] dtex1100 x 2x 3S100 / Z80.

[0048] Therefore, in case AB-2, the first twist rate is 165 revolutions per meter and the second twist rate is 150 revolutions per meter, while in case AB-3, the first twist rate is 100 revolutions per meter and the second twist rate is 80 revolutions per meter.

[0049] Figure 4 The results of this comparison are shown, where the pretension experienced by the reinforcing yarn during the test is recorded on the X-axis in Newtons (N). Stiffness is recorded on the Y-axis in Pussey & Jones (P&J). It should be noted that a smaller P&J value indicates greater stiffness than a larger P&J value.

[0050] from Figure 4 As can be seen, at a low pretension of 4N, the P&J hardness of embodiment AB-1 according to the present invention is 34, significantly higher than AB-2 (only 21) and slightly higher than AB-3 (32). In other words, compared with reinforcing yarns in the prior art, the reinforcing yarn 10 according to the present invention is relatively softer radially at low pretension. However, at a significantly higher pretension of 50N, the P&J hardness of embodiment AB-1 according to the present invention is only 20. This hardness is lower than the P&J hardness of AB-3 (24) and only slightly higher than the P&J hardness of AB2 (18). In other words, the reinforcing yarn 10 according to the present invention is harder radially at higher pretension or at least similar to the hardness of reinforcing yarns in the prior art.

[0051] The compression sleeve 200 according to the invention advantageously utilizes the significant difference in radial stiffness of the reinforcing yarns 10 according to the invention. That is, in the compression sleeve according to the invention, a plurality of reinforcing yarns 10, which are longitudinal yarns 220 extending parallel to the axis 1 of the compression sleeve 200, constitute the first layer of the reinforcing structure 100. Furthermore, the circumferential yarns 230 of these reinforcing yarns 10 are spirally wound radially outward around axis A relative to the first layer (see...). Figure 7 Multiple reinforcing yarns constitute the second layer of the reinforcing structure 100. Preferably, the entire reinforcing structure 100 of the pressure sleeve 200 according to the invention consists of only these two layers.

[0052] Pressure sleeve 200 can be like Figure 7 It is manufactured as illustrated. Figure 7 A simplified schematic side view shows an apparatus for manufacturing a pressure sleeve 200 according to the invention. In this example, the apparatus has exactly one cylindrical winding mandrel. A plurality of reinforcing yarns 10, designed as longitudinal yarns 220, are spaced apart from each other on the periphery. A polymer is applied to the radially outermost cover surface of the winding mandrel to lay a polymer layer 240. Furthermore, for example, circumferential yarns 230 are helically embedded in the polymer of the polymer layer 240. After being embedded in the polymer, the circumferential yarns 230, together with the longitudinal yarns 220, constitute the reinforcing structure 100 of the completed pressure sleeve 200 according to the invention. According to the invention, the circumferential yarns 230 are in contact with the longitudinal yarns 220, i.e., when viewed radially along the pressure sleeve 200, there is no distance between the circumferential yarns and the longitudinal yarns.

[0053] The mandrel is rotatably supported about its longitudinal axis, which coincides with the longitudinal axis A of the pressure sleeve 200 to be manufactured. This longitudinal axis extends orthogonally into the drawing plane. A casting material, such as a castable, curable elastomeric polymer, like polyurethane, is supplied from above via conduit 300 through casting nozzle 310 onto the radially outermost cover surface of the mandrel or onto the longitudinal yarn 220. This casting material can be selected, for example, in terms of its pot life and viscosity, such that it does not drip from the mandrel during casting. During this time, the mandrel rotates about its longitudinal axis in the direction of the arrow. Simultaneously with this rotation, the casting nozzle 310, through a suitable... Figure 7 The guiding device, not further shown, guides the material relative to the winding mandrel along the longitudinal axis A, parallel to the longitudinal axis. Simultaneously with the pouring of the material, at least one circumferential yarn 230 is unwound and spirally wound onto the rotating winding mandrel to form a helix. During this process, the pouring material can pass through the longitudinal yarn 220 to reach the winding mandrel. In this example, the polymer forms the innermost radially concentric polymer layer, preferably an elastomer, such as polymer layer 240, after the curing step. Furthermore, additional polymer layers can be laid radially outward if necessary. Preferably, however, the entire reinforcing structure 100 is completely embedded within the innermost radially concentric polymer layer 240.

[0054] The casting material exiting from the casting nozzle 6 is a mixture of a prepolymer and a crosslinking agent. The prepolymer is prepared from a prepolymer container (not shown), in which it is stored or stirred. The prepolymer may include isocyanates and polyols according to the invention. The isocyanates and polyols can be present in the prepolymer container, for example, in the form of a prepolymer composed of the aforementioned substances. The crosslinking agent can be prepared in a crosslinking agent container. The prepolymer container and the crosslinking agent container are associated with equipment for manufacturing the press sleeve 200. The prepolymer container and the crosslinking agent container are fluidly connected via pipelines (not shown) to a mixing chamber (not shown) connected upstream of the casting nozzle 310 in the flow direction. That is, the prepolymer-crosslinking agent mixture is prepared upstream and outside of the casting nozzle 310, i.e., the prepolymer-crosslinking agent mixture is formed by mixing in the mixing chamber. Independent of the preparation of the mixture, the mixture is then laid on the surface of a mandrel to form at least one polymer layer of the press sleeve 200.

[0055] Through this continuous casting process, also known as centrifugal casting, an endless, closed sleeve-shaped pressure sleeve 200 is gradually created on the width of the mandrel, which is closed around the longitudinal axis a of the mandrel. The inner circumference of the pressure sleeve is substantially equivalent to the outer circumference of the mandrel 4.

[0056] Preferably, the longitudinal yarn 220 is pre-tensioned with a greater pretension, for example, 50 N, compared to at least one circumferential yarn 230, whereas at least one circumferential yarn can be pre-tensioned with only 4 N when the reinforcing structure 100 is embedded in the polymer layer 240. Therefore, the stiffness of the reinforcing yarn 10 constituting the first layer of the reinforcing structure 100 as longitudinal yarn 220 according to the invention is significantly higher than that of at least one reinforcing yarn 10 constituting the second layer of the reinforcing structure 100 as circumferential yarn 230 according to the invention. This has a favorable effect on the resistance of the pressure sleeve 200 according to the invention during wet covering processes.

[0057] exist Figure 6 The diagram shows a schematic side view of a partially sectional section of a shoe press 500, which includes, according to the invention, a pressure roller 400, such as a shoe roller and a mating roller 450. The shoe roller 400 and the mating roller 450 are arranged parallel to each other about their longitudinal axes. The shoe roller and the mating roller together form or define an elongated pressure gap 510.

[0058] The mating roller 450 is composed of a cylindrical roller that rotates about its longitudinal axis, while the shoe-type pressure roller 400 consists of a pressure shoe 410, a fixed frame supporting the pressure shoe, and a pressure sleeve 200 according to the invention. The pressure shoe 410 and the frame are fixedly arranged relative to the mating roller 450 or the pressure sleeve 200. This means that the pressure shoe and the frame do not rotate. Here, the pressure shoe 410 is supported by the frame and is pressed against the radially innermost surface of the pressure sleeve 200 surrounding the pressure shoe or frame by a hydraulically pressed element (not shown). The pressure sleeve 200, which circumferentially surrounds the pressure shoe 410 and the frame, rotates about its longitudinal axis A in the opposite direction of rotation to the mating roller 450. The relatively long pressure gap 510 is created by the concave design of the pressure shoe 410 on its side facing the mating roller 450.

[0059] The shoe press 500 is particularly suitable for dewatering fiber webs FB. During operation of the shoe press 500, the fiber web FB, along with one or two pressure felts 520, is guided through a pressure gap 510. In the current case, exactly two pressure felts 520 clamp the fiber web FB between them. As it passes through the extended pressure gap 510, pressure is indirectly applied to the fiber web FB within the extended pressure gap 510 via the pressure felts 520. This is achieved by the outermost radial surfaces of the mating rollers 450 and the outermost radial surfaces of the pressure sleeve 200 directly contacting the corresponding pressure felts 520. Liquid exiting the fiber web FB is temporarily contained by one or two pressure felts 520 and, possibly, recesses, particularly grooves (not shown), provided in the surface of the pressure sleeve. After exiting the extended pressure gap 510, the liquid contained in the recesses of the pressure sleeve 200 is ejected, after which the pressure sleeve 200 re-enters the pressure gap 510. Furthermore, after leaving the pressure gap 510, the water contained in the pressure felt 520 is removed by the suction element.

[0060] In another embodiment of the invention, not shown in the figures, the pressure felt 520 is omitted. In this case, the fiber web FB is in direct contact with the pressure sleeve 200 on one side and with the mating roller 450 on the other side, the pressure sleeve and the mating roller together forming a pressure gap 510. The latter can be implemented as a heated drying cylinder.

[0061] List of reference numerals

[0062] 10 Reinforced Yarn

[0063] 20 Initial twisted strands

[0064] 30 fiber bundles

[0065] 100 Reinforced Structure

[0066] 200 compression sleeve

[0067] 220 longitudinal yarns

[0068] 230 circumferential yarn

[0069] 240 polymer layers

[0070] 300 pipeline

[0071] 310 Pouring nozzle

[0072] 400 (boot-type) pressure roller

[0073] 410 Boots

[0074] 450 Pairing Rollers

[0075] 500 Shoe Press

[0076] 510 (extended) pressure gap

[0077] 520 Pressed Felt

[0078] A (compression sleeve) axis

[0079] AB-1 (According to the present invention) Example 1

[0080] AB-2 (According to the prior art) Example 2

[0081] AB-3 (According to the prior art) Example 3

[0082] FB fiber width

Claims

1. A pressure sleeve (200) comprising at least one polymer layer (240) in which a reinforcing structure (100) is embedded, wherein, The reinforcing structure (100) is designed as a yarn layer comprising a first layer radially inward and a second layer radially outward. The first layer consists of a plurality of longitudinal yarns (220) extending axially along the pressure sleeve (200), and the second layer consists of at least one circumferential yarn (230) extending circumferentially along the pressure sleeve (200). The longitudinal yarns (220) of the first layer are designed as reinforcing yarns (10), which are designed as twisted yarns by first twisting a plurality of single fibers or fiber bundles (30) together along a first twist direction and at a first twist rate to form a ply (20), and then twisting a plurality of such ply (20) together along a second twist direction opposite to the first twist direction and at a second twist rate. The first twist rate is less than the second twist rate, and when viewed radially along the pressure sleeve (200), the longitudinal yarns (220) and the at least one circumferential yarn (230) are arranged to contact each other.

2. The pressure sleeve (200) according to claim 1, characterized in that, At least one circumferential yarn (230) of the second layer is designed as the reinforcing yarn (10).

3. The pressure sleeve (200) according to claim 1, characterized in that, The first twist rate is equivalent to 70% to 90% of the second twist rate, wherein the first twist rate is between 70 and 90 revolutions per meter.

4. The pressure sleeve (200) according to claim 3, characterized in that, The first twist rate is between 75 and 85 revolutions per meter.

5. The pressure sleeve (200) according to claim 3, characterized in that, The first twist rate is 80 revolutions per meter.

6. The pressure sleeve (200) according to claim 1, characterized in that, The first twisting direction is the S direction, and the second twisting direction is the Z direction.

7. The pressure sleeve (200) according to claim 1, characterized in that, Each initial twisted strand (20) consists of two single fibers or fiber bundles (30), and the resulting twisted yarn consists of three initial twisted strands (20).

8. The pressure sleeve (200) according to claim 1, characterized in that, In the pressure sleeve (200), the longitudinal yarn (220) of the first layer has a first pretension, and at least one circumferential yarn (230) of the second layer has a second pretension, wherein the first pretension is greater than the second pretension.

9. The pressure sleeve (200) according to claim 8, characterized in that, The first pretension is equivalent to at least 7 times and / or at most 13 times the second pretension.

10. The pressure sleeve (200) according to claim 1, characterized in that, The entire reinforcing structure (100) of the pressure sleeve (200) consists only of the first layer and the second layer.

11. The pressure sleeve (200) according to claim 1, characterized in that, At least one reinforcing yarn (10) designed as a twisted yarn has a coating.

12. The pressure sleeve (200) according to claim 1, characterized in that, At least one reinforcing yarn (10) designed as a twisted yarn has a fineness between 800 dtex and 1500 dtex.

13. The pressure sleeve (200) according to claim 12, characterized in that, The fineness is between 1000 dtex and 1200 dtex.

14. The pressure sleeve (200) according to claim 12, characterized in that, The fineness is 1100 dtex.

15. The pressure sleeve (200) according to claim 1, characterized in that, The initial twisted strands (20) are each composed of multiple fiber bundles (30), wherein each fiber bundle (30) has 180 to 230 monofilaments.

16. The pressure sleeve (200) according to claim 1, characterized in that, All yarns of the reinforcing structure (100) of the pressure sleeve (200) are consistent with at least one reinforcing yarn (10) designed as a twisted yarn.

17. The pressure sleeve (200) according to claim 1, characterized in that, All the yarns of the reinforcing structure (100) of the pressure sleeve (200) are constructed identically to each other.

18. A pressure roller (400) of a shoe press (500) for processing fiber web (FB), characterized in that, The pressure roller (400) has at least one pressure sleeve (200) according to any one of claims 1 to 17.

19. A shoe press (500) for processing fiber width (FB), the shoe press comprising a pressure roller (400) and a mating roller (450), the pressure roller and the mating roller together forming or defining an elongated pressure gap (510), wherein, The pressure roller (400) includes a surrounding pressure sleeve (200), characterized in that the pressure sleeve (200) is constructed according to any one of claims 1 to 17.

20. The shoe press (500) according to claim 19, characterized in that, The fiber web (FB) is a paper web, paperboard web, or tissue web.

21. An application of a compression sleeve (200) according to any one of claims 1 to 17 in a press for processing fiber webs (FB).

22. The application according to claim 21, characterized in that, The press is a shoe press (500).

23. The application according to claim 21, characterized in that, The fiber web (FB) is a paper web, paperboard web, or tissue web.

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