Belt

Abstract

To provide a belt for a fiber web machine.SOLUTION: The present invention relates to a belt for a textile web machine, and the belt (10) has an inner surface (11) and an outer surface (12). The belt (10) includes a plurality of parallel dewatering grooves arranged in a first direction (D1) on the outer surface (11) of the belt (10), wherein each dewatering groove has a width, the first dewatering groove (21) includes a shallow portion (30) having a first depth (32) and a deep portion (40) having a second depth (42), the first and second depths (32,42) being determined from the outer surface (12) of the belt (10) in the depth direction, and the first depth (32) being smaller than the second depth (42).SELECTED DRAWING: Figure 3c

Description

Technical Field

[0001] The present invention relates to a belt for a fiber web machine.

Background Art

[0002] Fiber web machines such as paper machines, as well as board paper machines, pulp machines, and tissue paper machines typically comprise a forming section, a press section, and a drying section. In papermaking, pulp manufacturing, and board paper manufacturing, it is an issue how to increase the amount of water removed from a wet fiber web in order to improve production efficiency without degrading the physical properties of the fiber web.

[0003] Today, these machines typically have felts and wires to support water removal or conveyance of the fiber web. Further, the fiber web machine may have a finishing section for improving end product properties such as a calendar machine for improving the smoothness of the dried fiber web.

[0004] Fiber web machines are well known to include many types of rolls arranged in different sections having different functions. For example, a sleeve roll can be used in the forming section to improve the removal of free water from the wet fiber material. A shoe press can be used, for example, in the press section to improve the removal of residual water in the internal fiber web. Both the sleeve roll and the shoe press require that the belt can operate properly.

[0005] However, there is still a need for a new belt for fiber web machines.

Summary of the Invention

Problems to be Solved by the Invention

[0006] The object of the present specification is to provide a belt for a fiber web machine.

Means for Solving the Problem

[0007] Aspects of the invention are characterized by what is described in the independent claims. Various embodiments of the present invention are disclosed in the dependent claims.

[0008] The fiber web machine according to this specification can be a paper machine, or can be a board paper machine, a pulp machine, or a tissue paper machine.

[0009] The fiber web machine may include a sleeve roll. The sleeve roll is typically arranged in the wire section of the fiber web machine. Thanks to the sleeve roll, the water removal in the wire section can be improved. In one embodiment, the belt according to this specification is a sleeve roll belt.

[0010] The fiber web machine may include a shoe press. The shoe press is typically arranged in the press section of the fiber web machine. Thanks to the shoe press, the water removal in the press section can be improved. Advantageously, the belt according to this specification is a shoe press belt. The novel dehydration groove can be particularly advantageous when the belt is a shoe press belt.

[0011] The belt according to this specification has an inner surface and an outer surface. During use, the belt typically forms a closed loop. The belt can be an impermeable belt. The technical effects include that a dehydration groove can be used to remove water from the fiber web fabric, and an oil layer can be provided on the inner surface of the belt without affecting the characteristics of the outer surface of the belt.

[0012] The belt can include a body including a body material. Further, the belt can include a reinforcing structure.

[0013] The outer surface of the belt can include a plurality of parallel dewatering grooves in a first direction. Each dewatering groove can have a width determined in a second direction. The second direction is transverse to the first direction.

[0014] Preferably, the first direction does not deviate by more than 10° from the machine direction, and the second direction does not deviate by more than 10° from the cross direction. More preferably, the first direction does not deviate by more than 5° from the machine direction, and the second direction does not deviate by more than 5° from the cross direction. Most preferably, the first direction is the machine direction, and the second direction is the cross direction with respect to the first direction.

[0015] The belt includes a first dewatering groove having a deep portion and a shallow portion. The technical effect of the shallow portion between the deep portions is to enhance water removal, which can contribute to an increase in web speed and production efficiency in a machine having dewatering grooves including the shallow portion and the deep portion.

[0016] The shallow portion has a first depth, which is determined as the minimum depth from the outer surface of the belt to the bottom of the shallow portion in the depth direction of the belt. The deep portion has a second depth, which is determined from the outer surface of the belt to the bottom of the deep portion in the depth direction of the belt. The first depth of the belt is smaller than the second depth.

[0017] The first depth can be in the range between 0 mm and 1.20 mm, preferably in the range between 0.02 mm and 0.40 mm. Further, the second depth can be in the range between 0.8 mm and 1.6 mm, preferably in the range between 1 mm and 1.4 mm. The technical effect is to achieve more effective transfer of water from the fiber web to the dewatering grooves and better removal of the water accumulated in the dewatering grooves from the dewatering grooves.

[0018] Preferably, the first depth is at least 1%, more preferably at least 2%, even more preferably at least 3%, and most preferably at least 5% with respect to the second depth determined from the outer surface of the belt in the depth direction. Further, the first depth is preferably less than 75%, more preferably less than 50%, even more preferably less than 25% with respect to the second depth determined from the outer surface of the belt in the depth direction. The technical effects include, inter alia, enhanced water removal from the fiber web to the dehydration grooves, thereby resulting in a higher dry content of the fiber web.

[0019] The first depth can be at least 0.2%, such as within the range between 0.2% and 20% with respect to the thickness of the belt. Alternatively or additionally, the second depth can be within the range between 6% and 30% with respect to the thickness of the belt. The technical effect is to achieve effective transmission of water from the fiber web to the dehydration grooves while maintaining the desired press capacity characteristics of the belt while using the dehydration grooves.

[0020] Preferably, the number of shallow portions is 1 / m to 50 / m determined from one first dehydration groove in the first direction, more preferably 20 / m to 40 / m, and most preferably 22 / m to 30 / m. The technical effect of said number is that the water flow rate in the dehydration groove is high and the removal of water from the dehydration groove is enhanced.

[0021] Each shallow portion has a center line determined as the location of the minimum depth of the shallow portion (or the center of the region having the minimum depth).

[0022] The distance between the center lines of the two closest shallow portions is less than 1000 mm measured from the first dehydration groove in the first direction, preferably at least 20 mm and 100 mm or less, more preferably at least 25 mm and 70 mm or less, and even more preferably at least 32 mm and 53 mm or less. The technical effect is to enhance the advantageous effects brought about by the shallow portions and achieve more controlled and better water removal from the dehydration grooves.

[0023] The shallow portion has a cross-sectional shape in a first direction that is determined from the bottom of the dewatering groove to the top of the shallow portion.

[0024] The cross-sectional shape can be tapered toward the outer surface of the belt. The technical effect is that the tapered shape provides a smooth transition without sharp edges, keeping the groove cleaner from fine fibers, filling additives, etc., and improving water removal from the dewatering groove.

[0025] In one embodiment, the shallow portions are arranged in such a way that each shallow portion extends from the bottom of the first dewatering groove in a direction forming an angle of at least 5° and 90° or less, preferably 80° or less, with respect to the bottom of the first dewatering groove. The technical effect is to improve the fine adjustment characteristics of the belt. The angle also has an effect on the amount of water to be removed.

[0026] The shallow portion can have a first length determined from the first dewatering groove in the first direction, and the deep portion can have a second length determined from the first dewatering groove in the first direction. The first length can be in the range of 5 mm to 35 mm, preferably in the range of 7 mm to 15 mm, measured from the first dewatering groove in the first direction. The second length can be in the range of 10 mm to 90 mm, preferably in the range of 20 mm to 45 mm, measured from the first dewatering groove in the first direction. The technical effect of this combination is to improve water removal from the fiber web to the dewatering groove and better removal of water from the dewatering groove.

[0027] The average length of the shallow part is preferably smaller than the average length of the deep part determined in the first direction. Preferably, each shallow part has a first length that is 60% or less, preferably 50% or less, of the average length of the deep part determined from the first dehydration groove in the first direction. The technical effect is to improve the removal of water from the fibrous web to the dehydration groove, and thus to obtain a higher dry content of the fibrous web to be dehydrated.

[0028] The average width of the shallow part can be at least 8% and 100% or less of the width of the first dehydration groove. Preferably, the average width of the shallow part is at least 35% and 100% or less, more preferably 50% or more, and most preferably 70% or more of the width of the first dehydration groove determined in the second direction. The technical effect is to avoid marking of the fibrous web to be dehydrated, especially when the shallow part has a substantially small depth.

[0029] The total amount of the first dehydration groove, i.e., the dehydration groove having the shallow part and the deep part, can be at least 50%, preferably at least 99%, and most preferably 100% determined from the total amount of all dehydration grooves. The technical effect is to achieve more effective transmission of water from the fibrous web to the dehydration groove and better controlled and better removal of water from the dehydration groove. Another technical effect is to improve the dehydration efficiency, thereby improving the production efficiency of the dehydration section of the fibrous web machine.

[0030] The dehydration grooves are arranged to form a total volume for water. Preferably, the total volume is 100 - 600 ml / m 2 and more preferably 200 - 500 ml / m 2 The technical effect is to provide such a total volume that can be used to achieve a higher dehydration and dry content of the fibrous web to be dehydrated, thereby improving the production efficiency of the fibrous web machine.

[0031] Therefore, the novel belt has many advantages. For example, thanks to the shallow portions between the deep portions, a higher dry content of the fiber web can be achieved by enhancing the removal of water from the dehydration grooves. This is because the deep portions can collect water, and the shallow portions can push the water away from the belt. In this way, the deep and shallow portions have a strong influence on the dehydration process to achieve a higher dry content of the fiber web.

[0032] Hereinafter, the present invention will be described with reference to the drawings.

Brief Description of the Drawings

[0033]

Figure 1a

Figure 1b

Figure 2a

Figure 2b

Figure 2c

Figure 3a

Figure 3b

Figure 3c

Figure 4a

Figure 4b

Modes for Carrying Out the Invention

[0034] The figures show some examples of the belt. The figures are illustrative and may not be to scale. Similar parts are indicated in the figures by the same reference numerals.

[0035] The solution will be described in more detail below with reference to several embodiments that should not be considered limiting.

[0036] (Description of reference signs) In this specification, reference is made to the figures with the following numbers and designations. D1 First direction of the belt D2 Second direction of the belt MD Travel direction of the belt CD Crossing direction of the belt C1 First curve of the sleeve roll C2 Second curve of the sleeve roll 1 Shoe press 2 Press shoe 3 Counter roll 4 Press zone 5, 5a, 5b Fibrous web, machine fabric, e.g. wire or felt 6 Fibrous web 7 Sleeve roll 8 Support shaft of the sleeve roll 9 Curve element of the sleeve roll 10 Belt 10a Thickness of the belt body 11 Inner surface of the belt 12 Outer surface of the belt 13a First end of the belt 13b Second end of the belt 14 Belt body 15 Attachment point of the belt 16 Outer edge of the belt 21 First dehydration groove 22 Width of the dehydration groove 23 Land between two adjacent dehydration grooves 24 Width of the land 30 Shallow part of the first dehydration groove 31 Center line of the shallow part 32 First depth, i.e. depth of the shallow part 33 Distance between the center lines of the two closest shallow parts in the first direction 34 Length of the shallow part in the first direction 40 Deep part of the dehydration groove 42 Depth of the deep part 44 Length of the deep part in the first direction

[0037] The embodiments and examples described in the claims and the specification can be freely combined with each other unless otherwise specified.

[0038] In this specification, the term "comprising" may be used as an open term, but this specification also includes the closed term "consisting of". Therefore, unless otherwise specified, the term "comprising" can be understood as "comprising or consisting of".

[0039] For the purposes of this specification and the claims, unless otherwise specified, all ranges include any combination of the disclosed maximum and minimum values, including any intermediate ranges therebetween, which may or may not be specifically listed herein.

[0040] Unless otherwise specified, all ranges and values are determined from the new belt. For example, the depth of the groove can decrease as the belt wears.

[0041] In this specification, the term "thickness" refers to the depth direction of the belt. On the other hand, the term "depth" refers to the thickness direction of the belt.

[0042] In this specification, the terms "travel direction" MD and "cross direction" CD are used. The running direction MD (i.e., the direction of running) refers to the rotation direction of the belt in use. The cross direction CD refers to the transverse direction with respect to the running direction MD of the belt. During use, the cross direction is substantially parallel to the rotation axis of the belt.

[0043] As used herein, the term "substantially parallel" means that one direction deviates from the substantially parallel direction by no more than 10 degrees, preferably no more than 3 degrees. Thus, for example, "substantially parallel to the direction of travel" means, as used herein, that a direction deviates from the direction of travel by no more than 10 degrees, preferably no more than 3 degrees.

[0044] A fiber web machine according to this specification may include at least one of a sleeve roll and a shoe press.

[0045] (Shoe press) Referring to FIG. 1a, a fiber web machine may include a shoe press 1.

[0046] Belt 10 can be a shoe press belt.

[0047] The shoe press with belt 10 can be used to dewater a fiber web. The shoe press typically includes a counter roll 4 and a press shoe 2, with a press zone formed therebetween. Thus, an extended press zone 4, i.e., a so-called long nip, is formed between press shoe 2 and counter roll 3. The function of the shoe press is typically to remove water from the fiber web.

[0048] The belt can be arranged or arranged in relation to the shoe press in such a way that during operation, the belt runs through the press zone between the counter roll and the press shoe.

[0049] Typically, the press shoe and the counter roll 1) a shoe press belt, 2) at least one papermaking fabric, and 3) a fiber web to be dewatered are pressed against each other within the press zone in such a way that they are compressed within the nip between the press shoe and the counter roll.

[0050] (Sleeve roll) Referring to FIG. 1b, the fiber web machine may include a sleeve roll 7.

[0051] The belt 10 can be a sleeve roll belt.

[0052] The sleeve roll 7 can be arranged within the forming section to improve water removal from the inside. The sleeve roll 7 with the belt 10 can be used to dewater the fiber web 6 on the wire 5.

[0053] The belt 10 can be arranged around the outer surface of the sleeve roll 7. The sleeve roll can include a support shaft 8. Thus, the belt 10 can be guided to go around the support shaft 8. Further, the sleeve roll 7 can include support elements that are spaced apart from each other on the support shaft 8. The belt 10 that can go around the outer surface of the sleeve roll can be supported by the support elements.

[0054] The belt 10 may be arranged in relation to the sleeve roll 7 in such a way that its outer surface 12 faces the fiber web 6 and its inner surface 11 faces the sleeve roll 7. Thus, the sleeve roll 7 can be surrounded by the belt 10 having a loop shape.

[0055] The sleeve roll 7 can further include a curved element 9. During operation, the belt typically runs through a dewatering zone on the curved element. Further, the wire 5 can be guided through curved dewatering zones C1, C2, which can be supported by the belt 10. The curved dewatering zones C1, C2 can include at least two partial curves C1, C2 such that the radius of curvature of the first partial curve C1 is greater than the radius of curvature of the second partial curve C2 following the first partial curve in the moving direction MD of the belt. This can improve water removal from the fiber web. The curved element 9 can be movable, i.e., the radius of curvature of the belt on the surface of the curved element can be controlled by moving the curved element.

[0056] (belt) The belt 10 according to the present specification can be configured to be a sleeve roll belt. Preferably, the belt according to the present specification is configured to be a shoe press belt.

[0057] The belt can have an inner surface 11 and an outer surface 12. The belt can form a closed loop, at least during operation, i.e., the belt 10 can be shaped like an endless loop.

[0058] The belt 10 has a circumference that is the length of one rotation and a thickness 10a. The thickness is the minimum dimension of the belt. The circumference can be selected to fit the belt to a sleeve roll or a shoe press. The circumference of the belt 10 is determined such that the inner diameter of the belt 10 is suitable for the purpose during operation. The circumference of the belt 10 is determined such that the inner diameter of the belt 10 is suitable for use during operation. The circumferences of the belts can be different. The inner diameter of the belt can be in the range between, for example, 700 mm and 2000 mm.

[0059] The belt 1 can be an impermeable belt. Thus, it is possible to use, for example, an oil layer on the inner surface 11 of the belt without affecting the properties of the outer surface 12 of the belt.

[0060] The thickness 10a of the belt can be at least 2 mm, more preferably at least 3 mm, and most preferably 3.5 mm or more. The thickness 10a of the belt can be 8 mm or less, more preferably 7 mm or less, and most preferably 6 mm or less. The technical effect is to provide a structure in which the belt having drainage grooves has good strength characteristics, particularly for sleeve roll belts and shoe press belts.

[0061] The belt includes a plurality of parallel drainage grooves on the outer surface of the belt arranged in a first direction D1. Each drainage groove has a width determined in a second direction D2.

[0062] Preferably, the drainage grooves extend in the machine direction MD, i.e., the rotation direction of the belt 10 during use, or at least substantially in the rotation direction of the belt 10 during use.

[0063] A land 23 is provided between two adjacent drainage grooves. Thus, the belt has a plurality of parallel lands 23 between adjacent drainage grooves. The land 23 can have a width within the range of 0.8 mm to 5 mm, preferably within the range of 1 mm to 3 mm, and most preferably within the range of 1.1 mm to 2.5 mm. Alternatively or additionally, the distance between the centerlines of two parallel and adjacent drainage grooves can be within the range of 1.5 mm to 7 mm, preferably within the range of 1.8 mm to 5.5 mm, and most preferably within the range of 2.0 mm to 4.5 mm. Alternatively or additionally, the width 22 of the drainage groove can be within the range of 0.5 mm to 2 mm, preferably within the range of 0.7 mm to 1.8 mm, and most preferably within the range of 0.8 mm to 1.6 mm. The technical effect of the above width and distance is to optimize the water removal from the fiber web to be dehydrated without causing undesirable markings on the fiber web together with the shallow and deep portions.

[0064] The first drainage groove 21 has a shallow portion and a deep portion arranged along the first drainage groove in the first direction. The shallow portion has a first depth, and the deep portion has a second depth. The first depth is smaller than the second depth. The technical effect is that water can be effectively removed from the web to the drainage groove.

[0065] The first depth of the shallow portion 30 is determined as the smallest depth of the shallow portion from the outer surface of the belt to the bottom of the shallow portion, within the range of 0 to 1.20 mm, preferably within the range of 0.01 mm to 1.0 mm, more preferably within the range of 0.02 mm to 0.8 mm, even more preferably within the range of 0.04 mm to 0.6 mm, even more preferably within the range of 0.05 mm to 0.4 mm, and most preferably 0.2 mm or less, and can be 0 mm or more. The technical effect is that less rewetting can occur with respect to the fiber web. Another technical effect is to avoid both the back splash phenomenon and the marking of the fiber web to be dehydrated.

[0066] The second depth of the deep portion 30 is determined from the bottom of the deep portion to the outer surface of the belt, 0.8 mm or more, preferably within the range of 0.9 mm to 1.6 mm, more preferably within the range of 1 mm to 1.5 mm, and most preferably within the range of 1.1 mm to 1.4 mm. The technical effect of the combination of the second depth and the first depth is to avoid the back splash phenomenon and rewetting. Preferably, the second depth is substantially the same throughout the depth portion.

[0067] The first depth can be at least 1%, more preferably at least 2%, even more preferably at least 3%, and most preferably at least 5% relative to the second depth. Additionally or alternatively, the first depth can be less than 75%, preferably less than 50%, and even more preferably less than 25% relative to the second depth, determined from the outer surface of the belt in the depth direction. The technical effect is to reduce the marking caused by the belt, and thus improve the surface properties of the fiber web to be manufactured.

[0068] A further technical effect of the reduction in the marking level is to achieve better properties of the final product, such as a coated and / or calendered fiber web.

[0069] The first depth is preferably at least 0.2%, such as within the range between 0.2% and 29%, preferably within the range between 2% and 15% relative to the thickness of the belt. Further, the second depth can be within the range between 6% and 30%, preferably within the range between 10% and 25% relative to the thickness of the belt. The technical effect is to achieve effective dehydration of the fiber web to be dehydrated.

[0070] With the above-mentioned depths of the shallow part and the deep part, water can be removed more efficiently from the web through the first dehydration groove. These benefits are typically well realized, and more of the above-described configurations are implemented on the belt.

[0071] The distance 33 between the centerlines 31 of the two closest shallow parts is preferably less than 1000 mm, more preferably less than 500 mm. To enhance the advantageous effect, the distance 33 between the centerlines 31 of the two closest shallow parts can be at least 20 mm and 100 mm or less, preferably at least 25 mm and 70 mm or less, and most preferably at least 30 mm and 50 mm or less, determined from the first dehydration groove in the first direction.

[0072] The shallow portions in the first drainage groove enhance the removal of water from the web, and their effectiveness can be improved as the number of shallow portions is maintained within the range of 1 / m to 50 / m, preferably between 20 / m and 40 / m. In that case, the best results can be achieved when the number of said shallow portions is 22 / m to 30 / m measured from the first drainage groove 21 in the first direction D1. Another technical effect of said number of shallow portions is that water can be effectively removed from the web to the drainage groove, and furthermore, less rewetting can occur with respect to the fiber web.

[0073] To further enhance the advantageous effect, the outer surface of the belt can include 5000 to 15000 shallow portions per square meter (m 2 ).

[0074] The shallow portion 30 can have an average length 34 in the range of 8 mm to 25 mm measured from the first drainage groove 21 in the first direction. Alternatively or additionally, the deep portion 40 can have an average length 44 within the range of 20 mm to 60 mm measured from the first drainage groove in the first direction. The technical effect is to substantially improve the drainage characteristics of the belt. Another technical effect is to achieve a good moisture profile for the fiber web to be manufactured.

[0075] The shallow portions can be arranged in such a way that each shallow portion extends from the bottom of the first drainage groove in a direction forming an angle of at least 5° and not more than 90° with respect to the bottom of the first drainage groove. Preferably, the shallow portions extend from the bottom of the first drainage groove in a direction forming an angle of 10° to 80° with respect to the bottom of the first drainage groove. The angle has an influence on the amount of water to be removed. The technical effect is to improve the fine-tuning characteristics of the belt.

[0076] As shown in FIG. 2b, the shallow portions can be positioned at least partially obliquely. The technical effect is that the influence of the shallow portions on drainage can be maintained at any position of the belt.

[0077] In one embodiment, the shallow portion, in the first direction, - a quadrilateral, - a rectangle, - a rectangle having at least one curved side and / or at least one curved edge, - a triangle, - a triangle having at least one curved side and / or at least one curved edge, - a trapezium, and - a trapezium having at least one curved side and / or at least one curved edge has at least one cross-sectional shape among them.

[0078] The technical effect of such a shape of the shallow portion is to improve its dehydration characteristics.

[0079] The shallow portion can include at least one curved side in the first direction. The shallow portion can include one or more concave sides in the first direction. The technical effect is to enhance the removal of water from the dehydration groove. Another technical effect is to improve the durability of the shallow portion during use.

[0080] The shallow portion can be shaped to have a downward opening, such as a substantially upside-down U-shaped or V-shaped cross-section in the first direction. The technical effect is to improve the dehydration characteristics because such a shaped shallow portion acts particularly well with the deep portion to remove water from the first dehydration groove.

[0081] The shallow portion can be arranged in a tapered shape such that the cross-sectional area determined in the first direction decreases towards the outer surface. Thus, the shape of the shallow portion may be tapered from the bottom to the top of the shallow portion. The technical effect is to keep the groove clean from small fibers, filling additives, etc. and improve the removal of water from the dehydration groove.

[0082] The effect of the shallow portion is typically enhanced when the number of drainage grooves including the shallow portion increases. Preferably, the number of the first drainage grooves is at least 140 / m, determined as the number of the first drainage grooves in the second direction, more preferably at least 200 / m, preferably at least 230 / m, preferably at most 670 / m, more preferably at most 560 / m, and preferably at most 500 / m.

[0083] The total amount of water in the drainage grooves is between 100 and 800 ml / m 2 , preferably between 200 ml / m 2 and 600 ml / m 2 , more preferably between 300 ml / m 2 and 500 ml / m 2 and can be between. The technical effect is to enhance the dewatering of the fiber web to be dewatered.

[0084] The belt is typically intended to be mounted on a pulp dryer, a paperboard machine, or a paper machine.

[0085] The belt can be intended to be mounted on a shoe press or a sleeve roll of a fiber web machine.

[0086] The belt can be manufactured by methods known to those skilled in the art.

[0087] Referring to FIG. 2a, in one example, the belt can have an outer edge 16 and / or a plurality of attachment points 15 for improved attachment of the belt. The belt can further include a reinforcing structure (not shown), for example, to improve the strength characteristics of the belt. The reinforcing structure, if used, can include, for example, yarn. In one example, the body 14 can include polyurethane, such as at least 50% by weight of polyurethane calculated from the total weight of the belt.

[0088] The present invention has been described with illustrations and examples. The present invention is not limited only to the above-described embodiments and may be modified within the scope of the appended claims.

Claims

1. A belt for a fiber web machine, the belt having an inner surface and an outer surface, the belt including a plurality of parallel dehydration grooves disposed in a first direction on the outer surface of the belt, each dehydration groove having a width, a first dehydration groove - having a shallow portion with a first depth, and - having a deep portion with a second depth, the first depth and the second depth being determined from the outer surface of the belt in a depth direction, the first depth being smaller than the second depth, the deep portion having an average length within a range of 20 mm to 60 mm measured from the first dehydration groove in the first direction, belt.

2. The belt according to claim 1, wherein the number of the shallow portions is 1 / m to 50 / m, or 20 / m to 40 / m, measured from the first dehydration groove in the first direction.

3. The belt according to claim 1, wherein the second depth is within a range of 0.8 mm to 1.6 mm, or within a range of 1 mm to 1.4 mm.

4. The first depth is - at least 1%, at least 2%, at least 3%, or at least 5% with respect to the second depth, and / or - less than 75% with respect to the second depth determined from the outer surface of the belt in the depth direction, the belt according to claim 1.

5. The belt according to claim 1, wherein the first depth is within a range of 0.01 mm to 1.2 mm, or within a range of 0.02 mm to 0.4 mm.

6. The belt according to claim 1, wherein the first depth is at least 0.2% with respect to the thickness of the belt.

7. The second depth is with respect to the thickness of the belt - within a range of 6% or more to 30% or less is the belt according to claim 1.

8. The belt according to claim 1, wherein the distance between the center lines of two closest shallow portions is at least 20 mm and 100 mm or less, or at least 25 mm and 70 mm or less, measured from the first dehydration groove in the first direction.

9. - the shallow portion is configured to be tapered such that the cross-sectional area in the first direction decreases toward the outer surface, and / or - the shallow portion includes one or more curved side surfaces, the belt according to claim 1.

10. The belt according to claim 1, wherein the shallow portion has an average length within a range of 8 mm to 25 mm, measured from the first dehydration groove in the first direction. **Claim 11** The belt according to claim 1, wherein the shallow portions are configured in such a way that each shallow portion extends from the bottom of the first dehydration groove in a direction forming an angle of at least 5° and 90° or less with respect to the bottom of the first dehydration groove. **Claim 12** The belt according to claim 1, wherein the width of the shallow portion is at least 8% of the width of the first dehydration groove, or at least 35% of the width of the first dehydration groove. **Claim 13** The belt according to claim 1, wherein at least 99% or all of the dehydration grooves include the shallow portion and the deep portion. **Claim 14** The belt according to claim 1, wherein the dehydration grooves are configured to form a total volume of 100 to 600 ml per square meter of water.

Images