Felt for papermaking and method for manufacturing felt for papermaking.

Description

1 / 35 Felt for papermaking and method for manufacturing felt for papermaking. CROSS-REFERENCE WITH RELATED ORDERS

[001] This application is based on and claims the benefit of priority of Japanese Patent Application No. 2024-042689, filed on March 18, 2024, the full content of which is incorporated herein by reference. BACKGROUND FIELD OF TECHNIQUE

[002] The present invention relates to a felt for papermaking and to a method for producing a felt for papermaking. BACKGROUND OF THE INVENTION

[003] A papermaking machine that removes water from a raw paper material is generally provided with a wire section, a press section and a dryer section. These wire section, press section and dryer section are arranged in this order along the direction of transfer of the wet paper roll.

[004] A wet paper roll is transferred and its moisture is removed as the wet paper roll is successively passed through papermaking devices provided in the wire section, the press section and the dryer section, and the wet paper roll is finally dried in the dryer section. In these sections, papermaking devices corresponding to a function of dewatering the wet paper roll (wire section), a function of squeezing water (press section) and a function of drying the wet paper roll (dryer section) are used.

[005] The press section generally comprises one or more press devices arranged in series along the direction of transfer of the wet paper roll. In each press device, a Petition 870250086614, dated 09 / 25 / 2025, p. 6 / 44 2 / 35 endless papermaking felt is placed, or finished papermaking felts are connected in the papermaking machine to form an endless papermaking felt that is placed in the press device. And, each press device has a roller press mechanism consisting of a pair of rollers opposite each other, or a shoe press mechanism having an endless shoe press belt placed between a roller and a concave-shaped shoe opposite the roller. The felt carrying a wet paper roll moves along the direction of transfer of the wet paper roll, passing through the roller press mechanism or the shoe press mechanism, where water is squeezed out of the wet paper roll by pressing the felt carrying the wet paper roll, so that the papermaking felt absorbs water continuously or the water passes through the felt to be drained to the outside.

[006] However, in the press device, in the center section for the pressurized section outlet, the pressure applied to the wet paper roll and papermaking felt is released rapidly, so that the volume of the papermaking felt and wet paper roll expands rapidly in this section. As a result, a negative pressure is generated in the papermaking felt and wet paper roll. In addition, a capillary phenomenon is also applied because the wet paper roll is made of fine fibers, resulting in the so-called rewetting phenomenon, in which the water that was absorbed by the papermaking felt is transferred back to the wet paper roll.

[007] Here, the amount of water (water content) in the wet paper roll at the exit of the press section is directly related to the energy consumption for drying in the dryer section in the subsequent stage. For example, if the water content of the wet paper roll Petition 870250086614, dated 09 / 25 / 2025, p. 7 / 44 3 / 35 increasing even slightly will considerably increase the energy required for drying (for example, if the water content of the wet paper roll increases by 1%, the energy increase will be about 4%). Therefore, it is preferable to reduce the water content of the wet paper roll as much as possible in the press section.

[008] Document JP 2007-100277 A proposes a transfer felt for paper manufacturing for shoe presses, characterized in that it comprises a base layer, a first layer of mat formed on the wet paper roll side surface of the base layer, a second layer of mat formed on the roll or shoe side surface of the base layer and a wet paper roll contact fiber layer comprising a hydrophilic fiber and formed on the wet paper roll side surface of the first layer of mat, so as to be in direct contact with the wet paper roll, wherein the hydrophilic fiber is fibrillated when pressed by the roll and the shoe.

[009] In addition, document JP 2004-143627 A proposes a press felt for papermaking, comprising a base body and web layers provided with a wet paper roll side layer and a press side layer, characterized in that a hydrophilic nonwoven fabric is placed within the wet paper roll side layer of the web layers. SUMMARY TECHNICAL PROBLEM

[010] As mentioned above, the amount of water (water content) in the wet paper roll at the exit of the press section is directly related to the energy consumption for drying in the dryer section in the subsequent stage. Therefore, it is preferable that the amount of water in the wet paper roll at the exit of the press section can be further reduced, further preventing the phenomenon of re-emergence. Petition 870250086614, dated 09 / 25 / 2025, page 8 / 44 4 / 35 wetting.

[011] Consequently, an objective of the present disclosure is to provide a felt for papermaking that can suppress the phenomenon of rewetting in the wet paper roll and sufficiently reduce the moisture content of the wet paper roll after it has been pressed, and a method for manufacturing it. SOLUTION TO THE PROBLEM

[012] The present inventors have made a diligent investigation to achieve the objective described above and have focused on a configuration in which a layer of blanket and a nonwoven fabric are arranged on a base fabric. Then, the present inventors discovered that there is a correlation between the phenomenon of new wetting and the resistance to needle penetration during the needle piercing treatment of the nonwoven fabric and, as a result of further diligent investigation, have arrived at the present invention.

[013] The essence of the present invention is as follows:

[014] (1) A felt for papermaking comprising a wet paper roll conveying surface for conveying wet paper rolls, comprising: a substrate; a layer of blanket that is placed on the transport surface side of the wet paper roll of the substrate and comprising a short fiber and a nonwoven fabric that is placed adjacent to the blanket layer on the transport surface side of the wet paper roll of the substrate; wherein the nonwoven fabric has a penetration resistance of 2.0 N / (100 g / m2 x number of needles) or less per needle when the basic weight of the fabric is 100 g / m2.

[015] (2)The felt for papermaking according to (1), wherein the nonwoven fabric comprises a continuous yarn. Petition 870250086614, dated 09 / 25 / 2025, p. 9 / 44 5 / 35

[016] (3) Felt for papermaking according to (1) or (2), wherein the nonwoven fabric comprises a hydrophilic fiber with an official moisture recovery of 10.0% or more.

[017] (4)The felt for papermaking according to (3), wherein the hydrophilic fiber comprises one or more types selected from the group consisting of cupra, rayon, lyocell, silk, hemp and wool.

[018] (5) A felt for papermaking according to any one of (1) to (4), wherein the fiber constituting the aforementioned nonwoven fabric has a fiber diameter equal to or greater than 5.0 μm and equal to or less than 30 μm.

[019] (6) Papermaking felt according to any one of (1) to (5), wherein the nonwoven fabric is a spun nonwoven fabric.

[020] (7) Papermaking felt according to any one of (1) to (6), wherein the web layer is in contact with the nonwoven fabric and is placed on the substrate side of the nonwoven fabric.

[021] (8) Papermaking felt according to any one of (1) to (6), further comprising a second web layer which is placed on the wet paper roll carrying surface side of the substrate and which comprises a second short fiber; where the batting layer and the second batting layer are arranged through the nonwoven fabrics.

[022] (9)The felt for papermaking according to any one of (1) to (8), wherein the difference between the official moisture recovery of the fiber constituting the nonwoven fabric and the official moisture recovery of the short fiber is equal to or greater than 2.0% and equal to or less than 12%.

[023] (10)The felt for papermaking according to (8), wherein the difference between the official moisture recovery of the fiber constituting the nonwoven fabric and the official moisture recovery of the second short fiber is equal to or greater than 2.0% and equal to or less than 12%. Petition 870250086614, dated 09 / 25 / 2025, p. 10 / 44 6 / 35

[024] (11) Felt for papermaking according to any one of (1) to (10), wherein the fineness of the short fiber is equal to or greater than 2.0 dtex and equal to or less than 70 dtex.

[025] (12) The felt for papermaking according to (8) or (12), wherein the fineness of the second short fiber is equal to or greater than 2.0 dtex and equal to or less than 70 dtex.

[026] (13)A method for making a felt for papermaking, comprising a laminating step of a nonwoven fabric and a short fiber on one side of the substrate and performing a needle punching treatment to form the nonwoven fabric and a blanket layer consisting of the short fiber on one side of the substrate, wherein the nonwoven fabric has a penetration resistance of 2.0 N / (100 g / m2 x number of needles) or less per needle when the basic weight of the fabric is 100 g / m2. ADVANTAGEOUS EFFECTS OF THE INVENTION

[027] With the above configuration, it is possible to provide a felt for papermaking that can suppress the phenomenon of rewetting in a wet paper roll and sufficiently reduce the moisture content of the wet paper roll after it has been pressed, and a method for making it. BRIEF DESCRIPTION OF THE DRAWINGS

[028] FIG. 1 is a cross-sectional view in the transverse direction of the machine showing a felt for papermaking according to an embodiment of the present invention.

[029] FIG. 2 is a schematic diagram to illustrate a method for measuring the needle penetration resistance of a nonwoven fabric.

[030] FIG. 3 is a schematic diagram to illustrate the behavior of felt for papermaking and wet paper sheet. Petition 870250086614, dated 09 / 25 / 2025, page 11 / 44 7 / 35 before and after pressing in one embodiment of the present invention.

[031] FIG. 4 is a cross-sectional view in the machine direction showing a papermaking felt according to a modified embodiment of the present invention.

[032] FIG. 5 is a schematic diagram to illustrate a method for testing the compressibility property of water. DESCRIPTION OF THE MODALITIES

[033] Next, with reference to the drawings, preferred embodiments of a felt for papermaking and a method for manufacturing a felt for papermaking according to the present invention will be described in detail.

[034] 1. Felt for papermaking

[035] First, a felt for papermaking according to a preferred embodiment of the present invention will be described.

[036] FIG. 1 is a cross-sectional view in a transverse direction of the machine showing an example of a papermaking felt according to a preferred embodiment of the present invention. Note that in the drawings, each member has been emphasized in size as appropriate for ease of illustration and therefore does not indicate the actual proportion and size of each member. Herein, the aforementioned transverse direction of the machine may be referred to as CMD and the direction of the machine may be referred to as MD.

[037] The papermaking felt 1 shown in FIG. 1 is used to transport and transfer a wet paper roll and to squeeze the water from the wet paper roll in the press section of a papermaking machine. The papermaking felt 1 forms an endless strip-shaped body. That is, the papermaking felt 1 is an annular belt. Furthermore, the papermaking felt Petition 870250086614, dated 09 / 25 / 2025, page 12 / 44 8 / 35 paper 1 is normally placed so that its circumferential direction runs along a machine direction (MD) of the papermaking machine. Furthermore, in papermaking felt 1, one side of a surface is generally a wet paper roll conveying surface 41 that will be in contact with the wet paper roll, and the other side of a surface is a roll contact surface 51 that will support the papermaking felt 1.

[038] Felt for papermaking 1 comprises a substrate 10; a first layer of felt 20 and a nonwoven fabric 30 and a second layer of felt 40 are placed on the transport surface side of the wet paper roll 41 of the substrate 10; and a third layer of felt 50 is placed on the contact surface side of the roll. Furthermore, the first layer of felt 20 and the nonwoven fabric 30 and the second layer of felt 40 are arranged in this order from the substrate 10 towards the transport surface of the wet paper roll 41. Additionally, these layers of papermaking felt 1 are all joined together by needle-punching treatment.

[039] Substrate 10 is a fibrous reinforcing substrate that ensures the physical strength (such as tensile strength) of the papermaking felt 1.

[040] Substrate 10 is not particularly limited and, for example, a fabric consisting of warp yarns and weft yarns woven by a weaving machine, etc., can generally be used. A non-woven grid-like bobbin material in which warp rows and weft rows are superimposed on each other can also be used. Alternatively, the fabric, the grid-like material, etc., can be used in combination of two or more.

[041] As substrate materials 10, polyester (polyethylene terephthalate, polybutylene terephthalate, etc.), aliphatic polyamide (polyamide Petition 870250086614, dated 09 / 25 / 2025, p. 13 / 44 9 / 35 Polyamide 6, polyamide 11, polyamide 12, polyamide 612, etc.), aromatic polyamide (aramid), polyvinylidene fluoride, polypropylene, polyether ether ketone, polytetrafluoroethylene, polyethylene, sheep's wool, cotton, metal, etc., can be used alone or in combination of two or more.

[042] The fineness of the fiber that constitutes the substrate 10 is not particularly limited, and may be, for example, equal to or greater than 300 and equal to or less than 10,000 dtex, preferably equal to or greater than 500 and equal to or less than 6,000 dtex.

[043] Furthermore, the fineness of the fiber that constitutes the substrate 10 may vary depending on the part in which the fiber is used. For example, the warp yarns and the weft yarns of the substrate 10 may have different fineness.

[044] The thickness of the substrate 10 mentioned above is not particularly limited, and may be, for example, equal to or greater than 0.2 mm and equal to or less than 3.5 mm, preferably equal to or greater than 0.5 mm and equal to or less than 3.0 mm. The weight of 1 m2 of the substrate 10 is not particularly limited, and may be, for example, equal to or greater than 150 g / m2 and equal to or less than 1,200 g / m2, and preferably equal to or greater than 300 g / m2 and equal to or less than 1,000 g / m2.

[045] The first layer of blanket 20 is a short fiber layer provided adjacent to the substrate 10 on the transport surface side of the wet paper roll 41 of the substrate 10. On the transport surface side of the wet paper roll 41 of the first layer of blanket 20, a nonwoven fabric 30 is arranged adjacently.

[046] The short fiber material that constitutes the first layer of blanket 20 is not particularly limited, and a polyester (polyethylene terephthalate, polytrimethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, etc.), an aliphatic polyamide (polyamide 6, polyamide 66, polyamide 11, polyamide 12, polyamide 610, polyamide 612, Petition 870250086614, dated 09 / 25 / 2025, p. 14 / 44 10 / 35 etc.), an aromatic polyamide (aramid), polyvinylidene fluoride, polypropylene, polyether ether ketone, polytetrafluoroethylene, polyethylene, sheep wool, cotton, metals, etc., may be used alone or in combination of two or more types. Among those mentioned above, polyamide is preferred as the material for the short fiber from the points of view of abrasion resistance, compression recoverability, impact resistance, hydrophilicity, hydrolysis resistance, chemical resistance, etc.

[047] The fineness of the short fiber constituting the first layer of 20 blanket is not particularly limited, but is, for example, equal to or greater than 0.1 dtex and equal to or less than 200 dtex.

[048] Furthermore, the fineness of the first short fiber that constitutes the first layer of blanket 20 is not particularly limited, although it is, for example, equal to or greater than 0.1 dtex and equal to or less than 200 dtex, preferably equal to or greater than 2.0 dtex and equal to or less than 70 dtex, more preferably equal to or greater than 6.0 dtex and equal to or less than 70 dtex. By this configuration, the first layer of blanket 20 can have sufficient strength while sufficiently absorbing moisture from the wet paper roll through the capillary phenomenon caused by fine short fibers.

[049] The weight of 1 m2 of the first layer of blanket 20 is not particularly limited, and may be, for example, equal to or greater than 50 g / m2 and equal to or less than 800 g / m2, preferably equal to or greater than 50 g / m2 and equal to or less than 700 g / m2, and more preferably equal to or greater than 50 g / m2 and equal to or less than 600 g / m2. With this configuration, a moderate space for absorption of water under pressure can be maintained.

[050] The nonwoven fabric 30 is a layer provided adjacent to the first layer of web 20 on the wet paper conveying surface side 41 of the first layer of web 20. On the wet paper roll conveying surface side 41 of the nonwoven fabric 30, a Petition 870250086614, dated 09 / 25 / 2025, p. 15 / 44 11 / 35 The second layer of blanket 40 is laid adjacent.

[051] The nonwoven fabric 30 acts as a barrier layer to suppress moisture migration from the first layer of blanket 20 to the wet paper transport surface side when negative pressure is generated in the papermaking felt 1 and in the wet paper roll immediately after pressing, and thus suppresses the phenomenon of rewetting in the wet paper roll after pressing.

[052] Here, the present inventors focused on this function of the nonwoven fabric 30 as a barrier layer to suppress the rewetting phenomenon and investigated the conditions to improve the function. As a result, the present inventors found that there is a significant correlation between the needle penetration resistance of the nonwoven fabric 30 and the rewetting phenomenon, and arrived at the present invention. Specifically, the present inventors found that the rewetting phenomenon can be adequately suppressed and the moisture content of the wet paper roll after pressing can be sufficiently reduced when the nonwoven fabric 30 has a penetration resistance of 2.0 N / (100 g / m2 x number of needles) or less per needle when the basic weight of the fabric is 100 g / m2.

[053] Although the principle of such a correlation between resistance to needle penetration and the suppressive effect on the rewetting phenomenon is not clear, the present inventors consider the following. That is, when manufacturing felt for papermaking 1, it is necessary to perform a needle perforation treatment to join the layers to each other. In this case, a high resistance to needle penetration of the nonwoven fabric 30 means that many fibers in the nonwoven fabric 30 collide with the needle and become entangled with fibers in adjacent layers, for example, the first layer of Petition 870250086614, dated 09 / 25 / 2025, page 16 / 44 12 / 35 blanket 20 and the second layer of blanket 40.

[054] When many fibers in nonwoven fabric 30 become entangled with fibers from adjacent layers, the fibers in the nonwoven fabric 30 are dispersed in the thickness direction, thus substantially reducing the density of the nonwoven fabric 30 after needle perforation treatment. Therefore, it is considered that if the substantial density of the nonwoven fabric 30 is reduced, its function as a barrier layer, as described above, will be reduced. Consequently, it is considered that the substantial decrease in the density of the nonwoven fabric 30 will be suppressed by using nonwoven fabric 30 having a relatively low resistance to penetration against the needle and, as a result, the nonwoven fabric 30 will function sufficiently as a barrier layer.

[055] The penetration resistance of nonwoven fabric 30 for a basic weight of 100 g / m2 per needle may be within the range mentioned above, and is preferably equal to or less than 1.8 N / (100 g / m2 x number of needles), even more preferably equal to or less than 1.5 N / (100 g / m2 x number of needles) and particularly preferably equal to or less than 1.2 N / (100 g / m2 x number of needles). Thus, nonwoven fabric 30 can fully perform its function, and can further suppress the phenomenon of rewetting in the wet paper roll after pressing.

[056] The lower limit of the penetration resistance of the nonwoven fabric 30 for the basic weight of 100 g / m2 per needle is not particularly limited, although the penetration resistance is, for example, equal to or greater than 0.10 N / (100 g / m2 x number of needles), preferably equal to or greater than 0.30 N / (100 g / m2 x number of needles) and, even more preferably, equal to or greater than 0.50 N / (100 g / m2 x number of needles). This configuration allows the contact between the first layer of blanket 20 and the nonwoven fabric 30 created by the perforation. Petition 870250086614, dated 09 / 25 / 2025, page 17 / 44 13 / 35 with needle punching during manufacturing is maintained, makes the layering of the second layer of blanket 40 easy, can sufficiently increase the density of the nonwoven fabric itself 30 before needle punching treatment and can further suppress the phenomenon of rewetting in the wet paper roll after pressing.

[057] In addition, the penetration resistance of the nonwoven fabric described above for the basic weight of 100 g / m2 per needle can be measured as described below. FIG. 2 is a schematic diagram to illustrate a method for measuring the needle penetration resistance of a nonwoven fabric.

[058] The resistance to penetration of a nonwoven fabric against a needle can be measured using a tensile testing machine. First, the jigs 101A and 101B of the tensile testing machine shown in FIG. 2 are arranged in a vertical direction facing each other. To the upper jig 101A, a support 105 having a plurality of needles 103 is attached. The number of needles 103 is not particularly limited, although it may be, for example, equal to or greater than 10 and equal to or less than 100 needles. Furthermore, although the needle implantation density is not particularly limited, it may be, for example, equal to or greater than 0.030 needles / cm2 and equal to or less than 0.20 needles / cm2.

[059] The lower template 101B is a pedestal with a space in the center, in which a nonwoven fabric 30 compressed between two fixing plates 109 is arranged. Here, a plurality of nonwoven fabrics 30 are arranged in layers as needed, so that their total basic weight becomes approximately 100 g / m2. Note that the total basic weight of the layered nonwoven fabrics 30 does not need to be strictly 100 g / m2, and can be adjusted appropriately, for example, between 70 g / m2 and 150 g / m2. Petition 870250086614, dated 09 / 25 / 2025, page 18 / 44 14 / 35

[060] Furthermore, the fixing plate 109 is provided with a through hole 1091 corresponding to the position of the needle 103, and the fixing plate 109 is arranged in a relative position, so that the through hole 1091 and the needle 103 do not interfere with each other during measurement.

[061] In this way, while the nonwoven fabric 30 is being fixed, the needle 103 is moved to the side of the nonwoven fabric 30 using the tensile testing machine to penetrate the first tip of the needle 103 into the nonwoven fabric 30. The maximum value of the resistance force loaded on the needle 103 at this moment can be defined as the penetration resistance. Furthermore, the movement speed of the needle 103 can be, for example, equal to or greater than 50 mm / min and equal to or less than 400 mm / min.

[062] The penetration resistance obtained as above is converted, so as to be per 100 g / m2 of the basic weight of nonwoven fabric 30 and per needle 103 to obtain the penetration resistance per 100 g / m2 of the basic weight of nonwoven fabric 30 per needle as described above. Specifically, it is expressed as in the following Equation (1).

[063] R = Rt + Wnwf x 100 + Nndl (Equation 1)

[064] In the equation, R is the resistance to penetration of the nonwoven fabric 30 for the basic weight of 100 g / m2 per needle [N / (100 g / m2 x number of needles)], Rt is the maximum resistance force (N) of the nonwoven fabric 30 at the moment of needle penetration 103, Wnwf is the total basic weight (g / m2) of the nonwoven fabric 30 and Nndl is the number of needles 103.

[065] The penetration resistance of nonwoven fabric 30, as mentioned above, can be altered as appropriate by changing the material and fineness of the fibers that constitute the nonwoven fabric, the density of the nonwoven fabric, the shape of the nonwoven fabric, the manufacturing method, etc. Petition 870250086614, dated 09 / 25 / 2025, page 19 / 44 15 / 35

[066] The fiber material that constitutes the nonwoven fabric 30 is not particularly limited and, in addition to the materials listed as the short fiber material of the first layer of blanket 20, includes hydrophilic fibers, such as cellulose-based fibers, such as rayon, polynosic, lyocell, cupra, cellulose nanofibers, cotton and linen, and silk and wool, which may be used alone or in combination of two or more.

[067] Among those mentioned above, the fiber that constitutes the nonwoven fabric 30 preferably includes a hydrophilic fiber. When the nonwoven fabric 30 comprises a hydrophilic fiber, the nonwoven fabric 30 can easily retain moisture and, as a result, can more adequately suppress the phenomenon of rewetting after pressing.

[068] A hydrophilic fiber may be a fiber that has an official moisture recovery, for example, equal to or greater than 4.0%, preferably equal to or greater than 5.0%. For example, an official moisture recovery is 4.5% for nylon, 11.0% for rayon, 11.0% for polynosic, 13.0% for lyocell, 11.0% for cupra, 8.5% for cotton, 12.0% for hemp, 12.0% for silk and 13.0% for wool.

[069] The official moisture recovery of the hydrophilic fiber is most preferably equal to or greater than 8.0%, and particularly preferably equal to or greater than 10.0%. Because of this configuration, the nonwoven fabric 30 can retain moisture more easily, and as a result can further suppress the phenomenon of rewetting after pressing.

[070] Furthermore, the difference between the official moisture recovery of the fiber constituting the nonwoven fabric 30 and that of the short fiber constituting the first layer of blanket 20 is not particularly limited, although it is, for example, equal to or greater than 2.0% and equal to or less than 12%, and preferably equal to or greater than 4.0% and equal to or less than Petition 870250086614, dated 09 / 25 / 2025, p. 20 / 44 16 / 35 that is 10%. Thus, as there is a moderate difference in the official moisture recovery between the fiber that constitutes the nonwoven fabric 30 and the short fiber that constitutes the first layer of web 20, the moisture transferred to the side of the first layer of web 20 through the nonwoven fabric 30 during pressing is adequately discharged to the substrate 10 and out of the papermaking felt 1.

[071] Furthermore, the difference between the official moisture recovery of the fiber constituting the nonwoven fabric 30 and that of the short fiber constituting the second layer of web 40 is not particularly limited, although it is, for example, equal to or greater than 2.0% and equal to or less than 12%, and preferably equal to or greater than 4.0% and equal to or less than 10%. Thus, as there is a moderate difference in the official moisture recovery between the fiber constituting the nonwoven fabric 30 and the short fiber constituting the second layer of web 40, the nonwoven fabric 30 can easily retain moisture when negative pressure is generated in the papermaking felt 1 and in the wet paper roll immediately after pressing, thus more certainly suppressing the phenomenon of rewetting.

[072] Among those mentioned above, the fiber constituting the nonwoven fabric 30 preferably comprises one or more selected fibers of nylon, cupra, rayon, lyocell, silk, hemp and wool, and more preferably one or more selected fibers of cupra, rayon, lyocell, silk, hemp and wool. Nylon has moderate hydrophilicity as well as excellent strength. Other preferred fibers also have moderate strength and, in addition, have excellent hydrophilicity.

[073] In addition, the fiber that constitutes the nonwoven fabric 30 may be a short fiber yarn (200 mm or less), a long fiber yarn (more than 200 mm and 15,000 mm or less) or a continuous yarn. Among those mentioned above, the fiber that constitutes the nonwoven fabric 30 comprises Petition 870250086614, dated 09 / 25 / 2025, page 21 / 44 17 / 35 preferably a long fiber yarn and / or a continuous yarn, and more preferably a continuous yarn. When the fiber constituting the nonwoven fabric 30 is relatively long and its resistance to penetration is small, there would be less movement of the fibers of the nonwoven fabric 30, and the density of the nonwoven fabric 30 can be maintained high. Furthermore, the continuous yarn as used here refers to a yarn that is continuously manufactured in the manufacturing process and ideally does not have an end portion, and is a so-called filament whose end portion is formed for a reason related to processes such as, for example, cutting the nonwoven fabric 30.

[074] Furthermore, the diameter of the fiber constituting the nonwoven fabric 30, especially the diameter of the continuous yarn fiber, is not particularly limited, although it is, for example, equal to or greater than 5.0 μm and equal to or less than 30 μm, preferably equal to or greater than 10 μm and equal to or less than 25 μm. When the fiber constituting the nonwoven fabric 30 has a fineness that is equal to or greater than the lower limit value described above, the nonwoven fabric 30 can have sufficient strength while ensuring moderate water permeability during pressing.When the fiber that constitutes the nonwoven fabric 30 has a fineness that is equal to or less than the upper limit value described above, the nonwoven fabric 30 can have sufficient water retention capacity through the capillary phenomenon, so that moisture can migrate smoothly from the second layer of mat 40 to the nonwoven fabric 30 during pressing and, at the same time, the migration of moisture from the nonwoven fabric 30 to the second layer of mat 40 immediately after pressing can be suppressed.

[075] In addition, nonwoven fabric 30 can be manufactured by, for example, a dry method, a wet method, a spun method, a meltblown method or similar. Among those mentioned above, is Petition 870250086614, dated 09 / 25 / 2025, page 22 / 44 18 / 35 It is preferable that nonwoven fabric 30 be a spun nonwoven fabric manufactured using the spun method. In the spun method, it is possible to manufacture nonwoven fabric 30 with continuous yarns.

[076] In addition, nonwoven fabric 30 can be processed by a processing method, such as a thermal bonding method, a chemical bonding method, a needle punching method or a hydroentanglement (spunlace) method. By being processed in these ways, the penetration resistance of nonwoven fabric 30 can be adjusted.

[077] The weight of 1 m2 (basic weight) of nonwoven fabric 30 is not particularly limited, and may be, for example, equal to or greater than 10 g / m2 and equal to or less than 100 g / m2, preferably equal to or greater than 15 g / m2 and equal to or less than 60 g / m2, and more preferably equal to or greater than 20 g / m2 and equal to or less than 50 g / m2. By this configuration, nonwoven fabric 30 can ensure appropriate air permeability while functioning sufficiently as a barrier layer to suppress the phenomenon of rewetting. It is also noted that, to adjust the basic weight of nonwoven fabric 30, a plurality of nonwoven fabrics may be prepared, so as to be a target basic weight, for example, which are arranged in layers to make a single-layer nonwoven fabric 30.

[078] The second layer of mat 40 is a layer consisting of short fibers, provided adjacent to the nonwoven fabric 30 on the wet paper roll conveying surface side 41 of the nonwoven fabric 30. The second layer of mat 40 is arranged with the first layer of mat 20 through the nonwoven fabric 30. Furthermore, the second layer of mat 40 is located on the outermost layer of the papermaking felt 1, forming the wet paper roll conveying surface 41 for conveying the wet paper roll.

[079] The material for the short fiber constituting the second layer Petition 870250086614, dated 09 / 25 / 2025, page 23 / 44 19 / 35 of mat 40 (the second short fiber) is not particularly limited, and includes the materials that constitute the first layer of mat 20, which can be used alone or in combination of two or more types. Polyamide is preferred as the material for the short fiber from the points of view of abrasion resistance, compression recoverability, impact resistance, hydrophilicity, hydrolysis resistance, chemical resistance, etc.

[080] The fineness of the second short fiber that constitutes the second layer of mat 40 is not particularly limited, and is, for example, equal to or greater than 0.1 dtex and equal to or less than 200 dtex, preferably equal to or greater than 2.0 dtex and equal to or less than 70 dtex, and more preferably equal to or greater than 2.0 dtex and equal to or less than 30 dtex.

[081] Through this configuration, the second blanket layer can have sufficient strength, while at the same time providing the wet paper roll transport surface 41 with sufficient smoothness and, at the same time, sufficiently absorbing moisture from the wet paper roll through the capillary phenomenon caused by the second short fine fibers.

[082] The weight of 1 m2 of the second layer of membrane 40 is not particularly limited, and may be, for example, equal to or greater than 50 g / m2 and equal to or less than 800 g / m2, preferably equal to or greater than 50 g / m2 and equal to or less than 700 g / m2, and more preferably equal to or greater than 50 g / m2 and equal to or less than 600 g / m2. With this configuration, a moderate space for absorption of water under pressure can be maintained.

[083] The total basic weight of the first layer of blanket 20 and the second layer of blanket 40 may be equal to or greater than 100 g / m2 and equal to or less than 1,600 g / m2, preferably equal to or greater than 100 g / m2 and equal to or less than 1,400 g / m2, and more preferably Petition 870250086614, dated 09 / 25 / 2025, p. 24 / 44 20 / 35 100 g / m2 and equal to or less than 1,200 g / m2. The total basic weight of the first layer of mat 20 and the second layer of mat 40 is appropriately defined according to the intended characteristics, such as strength, porosity and air permeability of the papermaking felt 1.

[084] A third layer of mat 50 is a layer made up of short fibers, provided adjacent to the substrate 10 on the contact surface side of the roller 51 of the substrate 10. Furthermore, the third layer of mat 50 is located in the outermost layer of the papermaking felt 1, forming the contact surface of the roller 51 that comes into contact with the roller. Note that, without being limited to the embodiments illustrated, the papermaking felt 1 can also be constructed without a third layer of mat 50.

[085] The material for the short fiber that constitutes the third layer of mat 50 (the third short fiber) is not particularly limited, and includes the materials that constitute the first layer of mat 20, which may be used alone or in combination of two or more types. Polyamide is preferred as the material for the short fiber from the points of view of abrasion resistance, compression recoverability, impact resistance, hydrophilicity, hydrolysis resistance, chemical resistance, etc.

[086] The fineness of the third short fiber that constitutes the third layer of mat 50 is not particularly limited, and is, for example, equal to or greater than 3.0 dtex and equal to or less than 150 dtex, preferably equal to or greater than 6.0 dtex and equal to or less than 100 dtex, and more preferably equal to or greater than 10 dtex and equal to or less than 70 dtex. By this configuration, the third layer of mat 50 can have sufficient strength and abrasion resistance.

[087] The weight of 1 m2 of the third layer of membrane 50 is not particularly limited, and may be, for example, equal to or greater than 50 Petition 870250086614, dated 09 / 25 / 2025, p. 25 / 44 21 / 35 g / m2 and equal to or less than 200 g / m2. With this configuration, a moderate space for water absorption under pressure can be maintained.

[088] The weight of 1 m2 of felt for papermaking 1 is not particularly limited, and is, for example, in its entirety, equal to or greater than 250 g / m2 and equal to or less than 3,000 g / m2, and preferably equal to or greater than 400 g / m2 and equal to or less than 2,000 g / m2. Furthermore, the thickness of felt for papermaking 1 is not particularly limited, and is, for example, equal to or greater than 1.0 mm and equal to or less than 6.0 mm, and preferably equal to or greater than 2.0 mm and equal to or less than 4.0 mm.

[089] Above, the configuration of the papermaking felt 1 was described. As above, the papermaking felt 1 of the present embodiment can suppress the phenomenon of rewetting in the wet paper roll and sufficiently reduce the water content of the wet paper roll after being pressed. Specifically, with reference to FIG. 3, it can be explained as follows. FIG. 3 is a schematic diagram to illustrate the behavior of the papermaking felt and the wet paper roll before and after pressing according to the present embodiment. Note that although a single felt press roll mechanism has been exemplified as a press device in the figure, a similar explanation can be made for a single or double felt shoe press mechanism, or for a double felt press roll mechanism.

[090] As shown in FIG. 3, in the press section, the papermaking felt 1 carries the wet paper roll W on its wet paper roll conveying surface 41 and runs along the machine direction MD and passes through the press mechanism comprising press rollers 200A and 200B. At this point, in region 201, the wet paper roll W and the papermaking felt 1 have not yet entered the press mechanism and are not under Petition 870250086614, dated 09 / 25 / 2025, page 26 / 44 22 / 35 pressure in the thickness direction.

[091] Next, in the press region 203, which is the region where the wet paper roll W and the papermaking felt 1 entered the press mechanism, the wet paper roll W and the papermaking felt 1 are subjected to pressure in the thickness direction by the press rolls 200A and 200B and are compressed in the direction of the black arrow in the figure. Here, a portion of the moisture contained in the wet paper roll W is transferred from the transport surface of the wet paper roll 41 to the papermaking felt 1 due to the compression of the wet paper roll W in its thickness direction, and most of it is discharged from the papermaking felt 1, by the press roll 200B when 200B is a suction roll, or as a splash SP from the contact surface side of the roll 51 on the side of region 205 when 200B is a simple roll. Alternatively, it is discharged from the contact surface side of roller 51 on the side of region 201.On the other hand, the portion of moisture that was transferred to the papermaking felt 1, but not discharged, remains in the papermaking felt 1.

[092] Next, in the press region 205, which is the region where the wet paper roll W and the papermaking felt 1 exited the press mechanism, the wet paper roll W and the papermaking felt 1 are released from the pressure by the press rolls 200A and 200B and therefore expand rapidly. As a result, a negative pressure is generated in the wet paper roll W and the papermaking felt 1, and they begin to absorb ambient air and moisture.

[093] Here, focusing on the relationship between the wet paper roll W and the papermaking felt 1, when a negative pressure is generated in the wet paper roll W, the wet paper roll W begins to absorb air and moisture from the papermaking felt 1 (phenomenon Petition 870250086614, dated 09 / 25 / 2025, page 27 / 44 23 / 35 of rewetting). However, in the papermaking felt 1 according to the present embodiment, the nonwoven fabric 30 is placed between the first layer of mat 20 and the second layer of mat 40. The nonwoven fabric 30 has a sufficiently low resistance to penetration against needles so that the fibers are not dispersed in the thickness direction and the density of the nonwoven fabric 30 itself is high. As a result, the moisture transfer M on the contact surface side of the roll 51 of the nonwoven fabric 30 of the papermaking felt 1 to the transport surface side of the wet paper roll 41 is suppressed by the nonwoven fabric 30, and only a portion of the moisture, m, is transferred to the second layer of mat 40. In this way, the migration of moisture M is suppressed by the nonwoven fabric 30 and the rewetting phenomenon in the wet paper roll W is suppressed.

[094] In particular, as the nonwoven fabric 30 comprises a hydrophilic fiber, it has a greater capacity to retain moisture M and further suppress the migration of moisture M to the side of the second layer of blanket 40.

[095] Furthermore, in the present embodiment, the second layer of blanket 40 is arranged on the transport surface side of the wet paper roll 41 of the nonwoven fabric 30. This can give the second layer of blanket 40 functions such as providing the transport surface of the wet paper roll 41 with smoothness and adhesion to the wet paper roll W, while allowing the nonwoven fabric 30 to have a configuration specialized in suppressing moisture migration M. As a result, each function of the papermaking felt 1 is fully exercised, and the effect of suppressing the rewetting phenomenon in the papermaking felt 1 is further enhanced.

[096] Furthermore, in the present embodiment, the nonwoven fabric 30 is placed between the first layer of blanket 20 and the second layer Petition 870250086614, dated 09 / 25 / 2025, page 28 / 44 24 / 35 of blanket 40 on the transport surface side of the wet paper roll 41 of the substrate 10, i.e., between the blanket layers on the transport surface side of the wet paper roll 41 of the substrate 10. By this configuration, the volume of a portion of the papermaking felt 1 that is on the contact surface side of the roll 51 of the nonwoven fabric 30 can be relatively large, and the nonwoven fabric 30 can function as a barrier layer against further moisture present in that portion. As a result, the effect of suppressing the phenomenon of rewetting in the papermaking felt 1 is further enhanced.

[097] As above, papermaking felt 1 can suppress the phenomenon of rewetting in the wet paper roll and sufficiently reduce the water content of the wet paper roll after it has been pressed.

[098] 3. Modified examples

[099] Next, some modified examples of felt for papermaking according to the aforementioned embodiments should be explained. Below, the differences from the aforementioned embodiments are mainly explained, and descriptions of similar subjects are omitted. The characteristics of the modified examples described below and of the embodiments mentioned above can be applied individually, although two or more may be applied in combination, provided it is technically acceptable.

[100] 3.1. The First Modified Example

[101] FIG. 4 is a cross-sectional view in a machine direction showing a papermaking felt according to a modified embodiment of the present invention. The papermaking felt 1A shown in FIG. 4 has a substrate 10, a first layer of web 20A, a nonwoven fabric 30A and a third layer of web 50, and the second layer of web 40 is omitted. In addition Petition 870250086614, dated 09 / 25 / 2025, page 29 / 44 25 / 35 of this, the non-woven fabric 30A is placed between the first layer of mat 20A and the substrate 10. Such paper-making felt 1A can also adequately suppress the phenomenon of rewetting.

[102] 3.2 Second Modified Example

[103] In the embodiments described above, the papermaking felt 1 was described as having an endless shape, although the present invention is not limited to this. The papermaking felt according to the present invention may be a strip-shaped felt. In this case, at both ends of the papermaking felt machine, sewing loops are provided. Then, the sewing loops at both ends are engaged with each other, and a pin thread is inserted into the sewing loops to form an annular (endless) papermaking felt, which is then installed in the papermaking machine.

[104] 4. Method of making felt for papermaking

[105] Finally, methods for manufacturing a felt for papermaking according to the preferred embodiments of the present invention will be described. The method for manufacturing a felt for papermaking according to the present invention comprises a lamination step of a nonwoven fabric and a short fiber on one side of the substrate and performing a needle-punching treatment to form the nonwoven fabric and a mat layer consisting of the short fiber on one side of the substrate, wherein the penetration resistance of the nonwoven fabric for a basic weight of 100 g / m2 per needle is 2.0 N / (100 g / m2 x number of needles) or less. The method for manufacturing the felt for papermaking described in FIG. 1 is explained herein as an example.

[106] First, substrate 10 is prepared. Then, a short fiber card that will become the first layer of mat 20, the Petition 870250086614, dated 09 / 25 / 2025, pages 30 / 44 26 / 35 nonwoven fabric 30, a carding belt of second short fibers that will become the second layer of web 40, and a carding belt of short fibers that will become the third layer of web 50 are prepared. Then, these carding belts and the nonwoven fabric 30 are laminated together with the substrate 10. In this case, the carding belts, the substrate 10, and the nonwoven fabric 30 are laminated so that each layer of the papermaking felt 1 is formed in the order of the third layer of web 50, the substrate 10, the first layer of web 20, the nonwoven fabric 30, and the second layer of web 40. Furthermore, in this case, the number of carding belts and nonwoven fabrics 30 can be adjusted to provide the necessary basic weight.

[107] Next, needle punching treatment is carried out so that the cards, the nonwoven fabric 30 and the substrate 10 are entangled and integrated to give a paper felt precursor 1. It should be noted that, in the present embodiment, it has been explained that all between the cards, the nonwoven fabric 30 and the substrate 10 are laminated at once and collectively processed by needle punching treatment, but it is also possible that the cards are laminated one by one per layer onto the substrate 10 and subjected to needle punching treatment, and this process is repeated so that all layers are laminated and integrated.

[108] Here, the nonwoven fabric 30 has a relatively small resistance to penetration, as mentioned above. Therefore, the dispersion of fibers of the nonwoven fabric 30 in the thickness direction in the needle perforation treatment is suppressed, and the density of the nonwoven fabric 30 is maintained at a relatively high state. As a result, in felt for papermaking 1, also, the nonwoven fabric 30 can adequately suppress the phenomenon of rewetting in the wet paper roll.

[109] Finally, the precursor of felt for papermaking 1 is Petition 870250086614, dated 09 / 25 / 2025, page 31 / 44 27 / 35 subjected to chemical treatment, heat fixing, pressing work, etc., as necessary, to produce felt for papermaking 1.

[110] As above, the present invention has been described in detail based on preferred embodiments, although the present invention is not limited to them, and each component can be replaced by any that is capable of performing an equal function, or an optional component can be added.

[111] Examples

[112] The present invention will now be described more specifically with examples, although the present invention should not be limited to these examples.

[113] 1. Felt manufacturing for papermaking

[114] First, a fabric with the following configuration was prepared as the substrate:

[115] -Warp yarns: A twisted yarn composed of two fibers twisted together, each fiber consisting of two 330 dtex nylon monofilaments twisted together.

[116] - Weft yarns: A twisted yarn composed of three fibers twisted together, each fiber consisting of two 330 dtex nylon monofilaments twisted together.

[117] -Weaving pattern: 31 twill stitches (four twill stitches (3 / 1)), 44 warp threads / 5 cm, 40 weft threads / 5 cm.

[118] -Weight of 1 m2: 400 g / m2.

[119] Next, short fiber cards were prepared corresponding to each of the following layers and nonwoven fabrics.

[120] First layer of batting: nylon 6 fibers; fineness: 22 dtex; Weight per m2: 400 g / m2; official moisture recovery: 4.5%.

[121] Second layer of blanket: nylon 6 fibers; fineness: 22 dtex; weight of 1 m2: 100 g / m2; official moisture recovery: 4.5%. Petition 870250086614, dated 09 / 25 / 2025, pp. 32-44 28 / 35

[122] Third layer of blanket: nylon 6 fibers; fineness: 22 dtex; Weight per m2: 100 g / m2; official moisture recovery: 4.5%.

[123] In Examples 1 to 4, a cupra nonwoven fabric (official moisture recovery: 11%; 1 m2 weight: 20 g / m2; fiber diameter: 20 μm; a water jet processed spun nonwoven fabric (hydroentanglement method)) was used and the number of sheets was adjusted according to the required 1 m2 weight.

[124] In Examples 4 to 8, a rayon nonwoven fabric (official moisture recovery: 11%; 1 m2 weight: 20 g / m2; fiber diameter: 20 μm; a spun nonwoven fabric) was used, and the number of sheets was adjusted according to the required 1 m2 weight.

[125] In Examples 9 to 12, a lyocell nonwoven fabric was used (official moisture recovery: 13%; 1 m2 weight: 20 g / m2; fiber diameter: 16 μm; a spunlace nonwoven fabric), and the number of sheets was adjusted according to the required 1 m2 weight.

[126] In Examples 13 to 15, a nylon nonwoven fabric was used (official moisture recovery: 4.5%; 1 m2 weight: 20 g / m2; fiber diameter: 18 μm; a spun nonwoven fabric), and the number of sheets was adjusted according to the required 1 m2 weight.

[127] Next, the cards from the third layer of mat, the substrate, the first layer of mat and the second layer of mat were laminated in this order, and needle punch treatment was performed on them to produce papermaking felts of Examples 1 to 15 and comparative examples. Note that the needle punch density was 4000 times / inch2 (3000 times / inch2 on the front surface and 1000 times / inch2 on the back surface).

[128] 2. Evaluation

[129] (1) Resistance to penetration of nonwoven fabric

[130] Resistance to needle penetration was measured for each of the nonwoven fabrics used in Examples 1 to 15. Resistance Petition 870250086614, dated 09 / 25 / 2025, pp. 33 / 44 29 / 35 penetration was measured by performing a compression test using the tensile testing machine shown in FIG. 2. Specifically, several nonwoven fabrics 30 compressed by clamping plates 109 were fixed to a jig 101B. Here, the number of nonwoven fabrics 30 to be laminated was adjusted so that their weight of 1 m2 became approximately 100 g / m2.

[131] Thus, while the nonwoven fabric 30 was fixed, the needles 103 were moved to the side of the nonwoven fabric 30 using the tensile testing machine to penetrate the first needle tip into the nonwoven fabric 30. The maximum value of the resistance force loaded on the needles 103 at that moment was defined as the penetration resistance. In addition, the number of needles was 54, the area in which the needles are implanted was 602 cm2, the density of implanted needles was 0.090 cm / cm2 and the movement speed of the needles 103 was 200 mm / min. Furthermore, the needles used had a needle count of 32°, a point diameter of 0.08 mm, a point-to-first-tip distance of 6.35 mm, a point depth of 0.09 mm, an impulse of 0.01 mm and a point length of 0.5 mm.

[132] The penetration resistance obtained as above was converted to be per 100 g / m2 of the basic weight of nonwoven fabric 30 and per needle 103 to obtain the penetration resistance per 100 g / m2 of the basic weight of nonwoven fabric 30 per needle. Specifically, it was calculated based on the following Equation (1):

[133] R = Rt + Wnwf x 100 + Nndl (Equation 1)

[134] In the equation, R is the resistance to penetration of the nonwoven fabric 30 for the basic weight of 100 g / m2 per needle [N / (100 g / m2 x number of needles)], Rt is the maximum resistance force (N) of the nonwoven fabric 30 at the moment of needle penetration 103, Wnwf is the total basic weight (g / m2) of the nonwoven fabric 30 and Nndl is the number of needles 103. Petition 870250086614, dated 09 / 25 / 2025, pages 34 / 44 30 / 35

[135] (2) Water compression properties

[136] Felts for papermaking according to Examples 15 and Comparative Example were evaluated for their water compression property by the method shown below. FIG. 5 is a schematic diagram to illustrate the method for testing the water compression property.

[137] As shown in FIG. 5, first, on a metal pedestal 301, a papermaking felt F according to any of Examples 1 to 15 and Comparative Example that was cut to have a diameter of 7 cm was placed, and the moisture content of the papermaking felt F was adjusted to 30%. Here, the moisture content is the mass of water divided by the sum of the mass of the papermaking felt and the water.

[138] Next, three sheets of toilet paper were stacked as a model of a wet paper roll, which was moistened with water to adjust the moisture content to 80%. The moisture content is the mass of water divided by the sum of the mass of the toilet paper and the water. This was cut to have a diameter of 6 cm to form a wet paper roll W and placed on the felt for papermaking F. At this point, the dry weight of the wet paper roll W was 0.136 g and the moisture content of the wet paper roll W was 0.544 g.

[139] Next, a metal top plate 302 (6 kg) was allowed to fall freely from 20 cm above the wet paper roll W to press it. The pressing pressure at this point was set to 50 kg / cm2. Note that the top plate 302, which was made to fall freely, rebounds and moves upwards upon hitting the wet paper roll W. Therefore, the test was conducted by fixing the top plate 302 at the moment when the top plate 302 moves upwards after the first pressing so that the second pressing is not performed. Petition 870250086614, dated 09 / 25 / 2025, pp. 35 / 44 31 / 35

[140] The water content of the wet paper roll W after pressing was calculated from the mass of the wet paper roll W after pressing, the amount of water in the wet paper roll W (the dry weight of the wet paper roll W being subtracted from the weight of the wet paper roll W) and the dry weight of the wet paper roll W, and the dryness ΔK (%) was calculated as a value obtained by subtracting the water content of the wet paper roll W after pressing from 100. In this evaluation, the dryness ΔK (%) represents the degree of moisture content reduction by pressing. Generally, it is known that a 1% reduction in the moisture content of the wet paper roll in the press section can reduce the energy required for drying in the dryer section in the later stage by about 4%. The dryness ΔK (%) obtained and the estimated reducible energy for drying the Comparative Example calculated based on it are shown in Table 1.

[141] Table 1 Petition 870250086614, dated 09 / 25 / 2025, pages 36 / 44 32 / 35 Nonwoven Fabric Configuration Water Compression Property Evaluation Type Fiber Diameter (mm) Fiber Shape Manufacturing Method Weight of 1 m2 (g / m2) Penetration Resistance per 100g / m2 per 1 needle [N / (100g / m2 x number of needles)] ΔK (%) Estimated Energy Reduction for Drying (%) Example 1 Cupra 20 Continuous Yarns Spun 20 0.96 40.9 12.0 Example 2 Cupra 20 Continuous Yarns Spun 40 0.96 42.8 19.6 Example 3 Cupra 20 Continuous Yarns Spun 60 0.96 43.6 22.8 Example 4 Cupra 20 Continuous Yarns Spun 80 0.96 44.3 25.6 Example 5 Rayon 20 Continuous Yarns Spun 20 1.74 Example 6 Rayon 20 Continuous yarns Spun 40 1.74 40.2 9.2 Example 7 Rayon 20 Continuous yarns Spun 60 1.74 40.8 11.6 Example 8 Rayon 20 Continuous yarns Spun 80 1.74 41.2 13.2 Example 9 Lyocell 16 Short fibers Spunlace 20 1.78 39.1 4.8 Petition 870250086614, dated 09 / 25 / 2025, pages 37 / 44 33 / 35 Example 10 Lyocell 16 Short Fibers Spunlace 40 1.78 40.2 9.2 Example 11 Lyocell 16 Short Fibers Spunlace 60 1.78 40.9 12.0 Example 12 Lyocell 16 Short Fibers Spunlace 80 1.78 41.4 14.0 Example 13 Nylon 18 Continuous Yarns Spun 20 1.71 38.5 2.4 Example 14 Nylon 18 Continuous Yarns Spun 40 1.71 39.5 6.4 Example 15 Nylon 18 Continuous Yarns Spun 60 1.71 40.3 9.6 Comparative Example - - - - - - 37.9 - Petition 870250086614, dated 09 / 25 / 2025, pages 38 / 44 34 / 35

[142] As shown in Table 1, it has been demonstrated that the papermaking felts according to Examples 1 to 15 had a much better water compression property during pressing compared with the papermaking felt according to the Comparative Example, and that the rewetting phenomenon was adequately suppressed when using the papermaking felt according to Examples 1 to 15. Furthermore, it has been suggested that it is possible to greatly reduce the energy for drying in the dryer section after the press section by using the papermaking felts according to Examples 1 to 15.

[143] Furthermore, comparing Examples 13 to 15 and Examples 5 to 8, although the penetration resistance of the nonwoven fabrics used for this purpose was almost the same, the papermaking felts of Examples 5 to 8 were much better in water compression property when compared for a similar level of basic weight. This is considered to be because the official moisture recovery of the fibers constituting the nonwoven fabric is much greater for the rayon fibers of Examples 5 to 8, so that the nonwoven fabric in the papermaking felt retains moisture and suppresses the phenomenon of rewetting.

[144] Note that it has been observed that there is a tendency for the safety to be improved when the basic weight of the nonwoven fabric is increased. On the other hand, if the weight of 1 m2 of nonwoven fabric is set too large, the wet paper roll may break depending on the type or basic weight of the wet paper roll. Therefore, in the actual papermaking machine, it is necessary to select a nonwoven fabric with an appropriate basic weight. LIST OF REFERENCE SIGNS 1, 1A, 1B: Felt for papermaking 10: Substrate Petition 870250086614, dated 09 / 25 / 2025, pages 39 / 44 35 / 35 20, 20A, 20B: The first layer of blanket 30, 30A, 30B: Nonwoven fabric 40: Second layer of blanket 41: Transport surface of the wet paper roll 50: Third layer of blanket 51: Roller contact surface Petition 870250086614, dated 09 / 25 / 2025, pages 40 / 44

Claims

1 / 3 CLAIMS 1. Felt for papermaking comprising a wet paper roll conveying surface for conveying wet paper rolls, characterized in that it comprises: a substrate; a blanket layer that is placed on the wet paper roll conveying surface side of the substrate and comprising a short fiber and a nonwoven fabric that is placed adjacent to the blanket layer on the wet paper roll conveying surface side of the substrate; wherein the nonwoven fabric has a penetration resistance of 2.0 N / (100 g / m2 x number of needles) or less per needle when the basic weight of the fabric is 100 g / m2.

2. Felt for papermaking, according to claim 1, characterized in that the nonwoven fabric comprises a continuous yarn.

3. Felt for papermaking, according to claim 1 or 2, characterized in that the nonwoven fabric comprises a hydrophilic fiber with an official moisture recovery of 10.0% or more.

4. Felt for papermaking, according to claim 3, characterized in that said hydrophilic fiber comprises one or more types selected from the group consisting of cupra, rayon, lyocell, silk, hemp and wool.

5. Felt for papermaking, according to any one of claims 1 to 4, characterized in that the fiber constituting the nonwoven fabric has a fiber diameter equal to or greater than 5.0 μm and equal to or less than 30 μm.

6. Felt for papermaking, according to any Petition 870250018805, dated 11 / 03 / 2025, page 42 / 92 2 / 3 one of claims 1 to 5, characterized in that the nonwoven fabric is a spun nonwoven fabric.

7. Felt for papermaking, according to any one of claims 1 to 6, characterized in that the blanket layer is in contact with the nonwoven fabric and is placed on the substrate side of the nonwoven fabric.

8. Felt for papermaking, according to any one of claims 1 to 6, characterized in that it further comprises a second layer of mat which is placed on the transport surface side of the wet paper roll substrate and which comprises a second short fiber; wherein the mat layer and the second mat layer are arranged over nonwoven fabrics.

9. Felt for papermaking, according to any one of claims 1 to 8, characterized in that the difference between the official moisture recovery of the fiber constituting the nonwoven fabric and the official moisture recovery of the short fiber is equal to or greater than 2.0% and equal to or less than 12%.

10. Felt for papermaking, according to claim 8, characterized in that the difference between the official moisture recovery of the fiber constituting the nonwoven fabric and the official moisture recovery of the second short fiber is equal to or greater than 2.0% and equal to or less than 12%.

11. Felt for papermaking, according to any one of claims 1 to 10, characterized in that the fineness of the short fiber is equal to or greater than 2.0 dtex and equal to or less than 70 dtex.

12. Felt for papermaking, according to claims 8 or 10, characterized in that the fineness of the second short fiber is equal to or greater than 2.0 dtex and equal to or less than 70 dtex.

13. Method for manufacturing a felt for papermaking, characterized in that it comprises a lamination step of a nonwoven fabric and a short fiber on one side of the substrate and performing a needle-punching treatment to form the nonwoven fabric and a mat layer consisting of the short fiber on one side of the substrate, wherein the nonwoven fabric has a penetration resistance of 2.0 N / (100 g / m2 x number of needles) or less per needle when the basic weight of the fabric is 100 g / m2.

Images