Papermaking felt and method for manufacturing papermaking felt

Abstract

To provide a papermaking felt and a method for manufacturing the papermaking felt, capable of suppressing the re-wetting phenomenon of wet paper and sufficiently reducing the water content of the wet paper after pressing.SOLUTION: Disclosed is a papermaking felt having a wet paper carrying surface for carrying wet paper, which comprises a base material, a batt layer disposed on the wet paper carrying surface side of the base material and comprising short fibers, and a nonwoven fabric disposed on the wet paper carrying surface side of the base material adjacent to the batt layer, wherein the nonwoven fabric has a penetration resistance per needle per basis weight 100 g / m2 per 1 needle of 2.0 N / (100 g / m2*needle) or less.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a papermaking felt and a method for producing a papermaking felt. [Background technology]

[0002] A paper machine that removes moisture from paper stock generally includes a wire part, a press part, and a dryer part, which are arranged in this order along the direction in which the wet paper is transported.

[0003] The wet paper web is transferred to and transported through the papermaking tools provided in the wire part, press part, and dryer part, where moisture is removed, and finally dried in the dryer part. Each of these parts uses papermaking tools that correspond to the respective functions of dehydrating the wet paper web (wire part), squeezing water out (press part), and drying (dryer part).

[0004] The press part generally includes one or more press devices arranged in series along the wet paper web transport direction. Each press device is equipped with an endless papermaking felt, or an endless papermaking felt formed by connecting endless papermaking felts on a papermaking machine. Each press device has a roll press mechanism consisting of a pair of opposing rolls, or a shoe press mechanism in which an endless shoe press belt is interposed between a concave shoe facing the roll. The papermaking felt carrying the wet paper moves along the wet paper web transport direction, passing through the roll press mechanism or shoe press mechanism and being pressurized, thereby continuously absorbing moisture into the papermaking felt or passing the moisture through the papermaking felt and discharging it to the outside, thereby squeezing moisture out of the wet paper.

[0005] However, in the area from the center of the pressurizing section of the press machine to the outlet, the pressure applied to the wet paper and papermaking felt is suddenly released, causing the volume of the papermaking felt and wet paper to suddenly expand in this area. As a result, negative pressure is generated in the papermaking felt and wet paper, and because the wet paper is made of fine fibers, capillary action also occurs, causing the moisture absorbed in the papermaking felt to migrate back into the wet paper, a phenomenon known as rewetting.

[0006] Here, the moisture content of the wet paper web at the exit of the press part is directly related to the amount of energy consumed for drying in the subsequent dryer part. For example, even a slight increase in the moisture content of the wet paper web increases the energy required for drying by a significant amount (for example, if the moisture content of the wet paper web increases by 1%, the energy increase is approximately 4%). Therefore, it is preferable to reduce the moisture content of the wet paper web as much as possible in the press part.

[0007] Patent document 1 proposes a papermaking transport felt for a shoe press, comprising a base layer, a first batt layer formed on the wet paper web side surface of the base layer, a second batt layer formed on the roll or shoe side surface of the base layer, and a wet paper web contact fiber layer containing hydrophilic fibers and formed on the wet paper web side surface of the first batt layer so as to come into direct contact with the wet paper web, wherein the hydrophilic fibers are fibrillated by being pressed by the roll and the shoe.

[0008] Furthermore, Patent Document 2 proposes a papermaking press felt that is composed of a base body and a batt layer having a wet paper side layer and a press side layer, characterized in that a hydrophilic nonwoven fabric is arranged in the wet paper side layer of the batt layer. [Prior art documents] [Patent documents]

[0009] [Patent Document 1] Japanese Patent Application Laid-Open No. 2007-100277 [Patent Document 2] Japanese Patent Application Laid-Open No. 2004-143627 Summary of the Invention [Problem to be solved by the invention]

[0010] As mentioned above, the moisture content of the wet paper web at the press part outlet is directly related to the amount of energy consumed for drying in the subsequent dryer part. Therefore, it is preferable to further prevent rewetting and further reduce the moisture content of the wet paper web at the press part outlet.

[0011] SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a papermaking felt and a method for manufacturing the papermaking felt, which can suppress the rewetting phenomenon of wet paper and can sufficiently reduce the moisture content of wet paper after pressing. [Means for solving the problem]

[0012] The present inventors conducted extensive research to achieve the above object and focused on a configuration in which a batt layer and a nonwoven fabric are disposed on a base fabric. They then found that there is a correlation between rewetting and needle penetration resistance during needle punching of the nonwoven fabric. As a result of further extensive research, they arrived at the present invention.

[0013] The gist of the present invention is as follows. [1] A papermaking felt having a wet paper support surface that supports a wet paper, A substrate; a batt layer that is arranged on the wet paper support surface side of the substrate and that contains short fibers; a nonwoven fabric disposed adjacent to the batt layer on the wet paper web bearing surface side of the substrate, The nonwoven fabric has a basis weight of 100 g / m 2 -Penetration resistance per needle is 2.0N / (100g / m 2 -Papermaking felt (book) [2] The papermaking felt according to [1], wherein the nonwoven fabric contains continuous yarn. [3] The nonwoven fabric has a hydrophilic property with an official moisture regain of 10.0% or more. fiber The papermaking felt according to [1], comprising: [4] The papermaking felt according to [3], wherein the hydrophilic fibers include one or more selected from the group consisting of cupra, rayon, lyocell, silk, hemp, and wool. [5] The papermaking felt according to [1], wherein the diameter of the fibers constituting the nonwoven fabric is 5.0 μm or more and 30 μm or less. [6] The papermaking felt according to [1], wherein the nonwoven fabric is a spunbond nonwoven fabric. [7] The papermaking felt according to [1], wherein the batt layer is in contact with the nonwoven fabric and is positioned closer to the substrate than the nonwoven fabric. [8] Further, a second batt layer is arranged on the wet paper support surface side of the substrate and is composed of second short fibers, The papermaking felt according to [1], wherein the batt layer and the second batt layer are arranged with the nonwoven fabric sandwiched between them. [9] A papermaking felt according to [1], wherein the difference between the official moisture regain of the fibers constituting the nonwoven fabric and the official moisture regain of the short fibers is 2.0% or more and 12% or less.

[10] A papermaking felt according to [8], wherein the difference between the official moisture regain of the fibers constituting the nonwoven fabric and the official moisture regain of the second short fibers is 2.0% or more and 12% or less.

[11] The papermaking felt according to [1], wherein the fineness of the short fibers is 2.0 dtex or more and 70 dtex or less.

[12] The papermaking felt according to [8], wherein the fineness of the second short fibers is 2.0 dtex or more and 70 dtex or less.

[13] A method of manufacturing a laminated laminated laminated sheet, comprising: laminating a nonwoven fabric and staple fibers on one surface of a substrate and performing a needle punching process to form a batt layer made of the nonwoven fabric and the staple fibers on the one surface of the substrate; The nonwoven fabric has a basis weight of 100 g / m 2 -Penetration resistance per needle is 2.0N / (100g / m 2 - A method for manufacturing papermaking felt, which is as follows: [Effects of the Invention]

[0014] With the above-described configuration, it is possible to provide a papermaking felt and a method for manufacturing a papermaking felt that can suppress the rewetting phenomenon of wet paper and sufficiently reduce the moisture content of wet paper after pressing. [Brief explanation of the drawings]

[0015] [Figure 1] FIG. 1 is a cross-machine direction cross-sectional view showing a papermaking felt according to one embodiment of the present invention. [Figure 2] FIG. 2 is a schematic diagram for explaining a method for measuring needle penetration resistance of a nonwoven fabric. [Figure 3] FIG. 3 is a schematic diagram for explaining the behavior of the papermaking felt and the wet paper before and after pressing in one embodiment of the present invention. [Figure 4] FIG. 4 is a machine-direction cross-sectional view showing a papermaking felt according to a modified example of the present invention. [Figure 5] FIG. 5 is a schematic diagram for explaining the method of the water squeezing test. DETAILED DESCRIPTION OF THE INVENTION

[0016] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of a papermaking felt and a method for manufacturing a papermaking felt according to the present invention will be described in detail below with reference to the drawings.

[0017] <1. Papermaking felt> First, a papermaking felt according to a preferred embodiment of the present invention will be described. Fig. 1 is a cross-machine direction cross-sectional view showing an example of a papermaking felt according to a preferred embodiment of the present invention. In the drawing, the size of each component is appropriately exaggerated for ease of explanation, and the actual proportions and sizes of each component are not shown. Here, the cross-machine direction is also referred to as "CMD," and the machine direction is also referred to as "MD."

[0018] The papermaking felt 1 shown in Figure 1 is used in the press part of a papermaking machine to support and transport a wet paper and to squeeze water out of the wet paper. The papermaking felt 1 is an endless belt. That is, the papermaking felt 1 is a circular belt. The papermaking felt 1 is usually arranged so that its circumferential direction is along the machine direction (MD) of the papermaking machine. One side of the papermaking felt 1 usually serves as a wet paper support surface 41 that comes into contact with the wet paper, and the other side serves as a roll contact surface 51 that supports the papermaking felt 1.

[0019] The papermaking felt 1 includes a substrate 10, a first batt layer 20, a nonwoven fabric 30, and a second batt layer 40 arranged on the wet paper web support surface 41 side of the substrate 10, and a third batt layer 50 arranged on the roll contact surface side. The first batt layer 20, the nonwoven fabric 30, and the second batt layer 40 are arranged in this order from the substrate 10 toward the wet paper web support surface 41 side. All of these layers of the papermaking felt 1 are bonded to each other by needle punching.

[0020] The substrate 10 is a reinforcing fiber substrate that ensures the physical strength of the papermaking felt 1, such as tensile strength. The substrate 10 is not particularly limited, but for example, a woven fabric made by weaving warp and weft threads on a loom or the like is commonly used. Alternatively, a lattice-like material made by overlapping rows of warp and weft threads without weaving can also be used. Alternatively, two or more types of woven fabrics and lattice-like materials may be used in combination.

[0021] The material of the substrate 10 can be one or a combination of two or more of polyester (polyethylene terephthalate, polybutylene terephthalate, etc.), aliphatic polyamide (polyamide 6, polyamide 11, polyamide 12, polyamide 612, etc.), aromatic polyamide (aramid), polyvinylidene fluoride, polypropylene, polyether ether ketone, polytetrafluoroethylene, polyethylene, wool, cotton, metal, etc.

[0022] The fineness of the fibers constituting the substrate 10 is not particularly limited, but can be, for example, 300 to 10,000 dtex, and preferably 500 to 6,000 dtex. Furthermore, the fineness of the fibers that make up the base material 10 may differ depending on the part where the fibers are used. For example, the fineness of the warp and weft threads of the base material 10 may differ.

[0023] The thickness of the substrate 10 is not particularly limited, and can be, for example, 0.2 mm to 3.5 mm, preferably 0.5 mm to 3.0 mm. The basis weight of the substrate 10 is not particularly limited, and can be, for example, 150 g / m 2 More than 1,200g / m 2 or less, preferably 300 g / m 2 More than 1,000g / m 2 It can be as follows:

[0024] The first batt layer 20 is a short fiber layer provided adjacent to the substrate 10 on the wet paper web support surface 41 side of the substrate 10. A nonwoven fabric 30 is arranged adjacent to the wet paper web support surface 41 side of the first batt layer 20.

[0025] The material of the staple fibers constituting the first batt layer 20 is not particularly limited, and may be selected from the following: polyester (polyethylene terephthalate, polytrimethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, etc.), aliphatic polyamide (polyamide 6, polyamide 66, polyamide 11, polyamide 12, polyamide 610, polyamide 612, etc.), aromatic polyamide (aramid), polyvinylidene fluoride, polypropylene, polyether ether ketone, polytetrafluoroethylene, polyethylene, wool, cotton, metal, etc., either alone or in combination. Of the above, polyamide is preferred as the staple fiber material from the viewpoints of abrasion resistance, compression recovery, impact resistance, hydrophilicity, hydrolysis resistance, chemical resistance, etc.

[0026] The fineness of the short fibers constituting the first batt layer 20 is not particularly limited, but is, for example, 0.1 dtex or more and 200 dtex or less.

[0027] The fineness of the first short fibers constituting the first batt layer 20 is not particularly limited, but is, for example, 0.1 dtex to 200 dtex, preferably 2.0 dtex to 70 dtex, and more preferably 6.0 dtex to 70 dtex. This ensures that the first batt layer 20 has sufficient strength and can absorb sufficient moisture from the wet paper web by capillary action caused by the fine short fibers.

[0028] The basis weight of the first batt layer 20 is not particularly limited, but is, for example, 50 g / m 2 More than 800g / m 2 Less than 50 g / m 2 More than 700g / m 2 Less than 50 g / m 2 More than 600g / m 2 This allows an appropriate amount of space to be maintained for absorbing water under pressure.

[0029] The nonwoven fabric 30 is a layer provided adjacent to the first batt layer 20 on the wet paper web support surface 41 side of the first batt layer 20. The second batt layer 40 is arranged adjacent to the wet paper web support surface 41 side of the nonwoven fabric 30.

[0030] When negative pressure is generated in the papermaking felt 1 and the wet paper immediately after pressing, the nonwoven fabric 30 functions as a barrier layer that suppresses the migration of moisture from the first batt layer 20 side to the wet paper support surface side, thereby suppressing the rewetting of the wet paper after pressing.

[0031] The inventors of the present invention focused on the rewetting suppression function of the nonwoven fabric 30 as a barrier layer and investigated the conditions for improving this function. As a result, they found that there is a strong correlation between the needle penetration resistance of the nonwoven fabric 30 and the rewetting phenomenon, leading to the present invention. Specifically, for the nonwoven fabric 30, a basis weight of 100 g / m 2 -Penetration resistance per needle is 2.0N / (100g / m 2 The present inventors have found that if the temperature is 100°C or less, the rewetting phenomenon can be suitably suppressed and the moisture content of the wet paper after pressing can be sufficiently reduced.

[0032] Although the principle behind the correlation between the needle penetration resistance and the rewetting suppression effect is not clear, the present inventors believe as follows: When manufacturing papermaking felt 1, needle punching is required to bond each layer. In this case, a high needle penetration resistance of nonwoven fabric 30 means that many fibers in nonwoven fabric 30 collide with the needles and become entangled with fibers in adjacent layers, for example, first batt layer 20 and second batt layer 40.

[0033] If many of the fibers in the nonwoven fabric 30 become entangled with the fibers of adjacent layers, the fibers will be dispersed in the thickness direction of the nonwoven fabric 30, and the effective density of the nonwoven fabric 30 after needle punching will decrease accordingly. For this reason, it is believed that a decrease in the effective density of the nonwoven fabric 30 will reduce its function as a barrier layer as described above. Therefore, by using a nonwoven fabric 30 with a relatively low needle penetration resistance, it is believed that the decrease in the effective density of the nonwoven fabric 30 can be suppressed, and as a result, the nonwoven fabric 30 will function satisfactorily as a barrier layer.

[0034] Nonwoven part 30 basis weight 100g / m 2 The penetration resistance per needle should be within the above range, but is preferably 1.8 N / (100 g / m 2 1.5N / (100g / m 2 1.2N / (100g / m 2 This allows the nonwoven fabric 30 to fully exert its functions, and the rewetting phenomenon of the wet paper after pressing can be further suppressed.

[0035] In addition, the basis weight of the nonwoven fabric 30 is 100 g / m 2 The lower limit of the penetration resistance per needle is not particularly limited, but the penetration resistance is, for example, 0.10 N / (100 g / m 2 100g / m or more, preferably 0.30N / (100g / m 2 100g / m or more, more preferably 0.50N / (100g / m2 This maintains contact between the first batt layer 20 and the nonwoven fabric 30 due to needle punching during manufacturing, facilitating lamination of the second batt layer 40, and also allows the density of the nonwoven fabric 30 itself before needle punching to be sufficiently increased, further suppressing the rewetting of the wet paper after pressing.

[0036] The nonwoven fabric 30 has a basis weight of 100 g / m 2 The penetration resistance of each needle can be measured as follows: Figure 2 is a schematic diagram illustrating a method for measuring the penetration resistance of a needle of a nonwoven fabric.

[0037] The needle penetration resistance of a nonwoven fabric can be measured using a tensile tester. First, jigs 101A and 101B of the tensile tester shown in FIG. 2 are arranged so as to face each other in the vertical direction. A holder 105 having a plurality of needles 103 arranged thereon is attached to the upper jig 101A. The number of needles 103 is not particularly limited, but can be, for example, 10 to 100. The needle density is also not particularly limited, but can be, for example, 0.030 needles / cm. 2 Over 0.20 strands / cm 2 It can be:

[0038] The lower jig 101B is a base with a space in the center, and the nonwoven fabric 30 sandwiched between two fixing plates 109 is placed on top of it. Here, the nonwoven fabric 30 has a basis weight of 100 g / m 2 The nonwoven fabric 30 is stacked in multiple layers as needed so that the nonwoven fabric 30 is close to the surface. The basis weight of the stacked nonwoven fabrics 30 is strictly 100 g / m 2 It does not have to be, for example, 70 g / m 2 More than 150g / m 2 The following may be adjusted as appropriate:

[0039] Furthermore, fixed plate 109 is provided with through-hole 1091 corresponding to the position of needle 103, and fixed plate 109 is positioned relative to needle 103 so that through-hole 1091 and needle 103 do not interfere with each other during measurement.

[0040] With nonwoven fabric 30 fixed in this manner, needle 103 is moved toward nonwoven fabric 30 using a tensile tester, causing the first barb of needle 103 to penetrate nonwoven fabric 30. The maximum value of the resistance force applied to needle 103 at this time can be taken as the penetration resistance. The moving speed of needle 103 can be, for example, 50 mm / min or more and 400 mm / min or less.

[0041] The penetration resistance obtained as described above was measured for a nonwoven fabric 30 having a basis weight of 100 g / m 2 The weight of the nonwoven fabric 30 is calculated so that the number of needles 103 is one. 2 The penetration resistance per needle is calculated. Specifically, it is expressed as the following formula (1).

[0042] R=R T ÷W NWF ×100÷N NDL (Formula 1) Here, R is the basis weight of the nonwoven fabric 30 (100 g / m 2 -Penetration resistance per needle [N / (100g / m 2 ·Book)], R T is the maximum resistance force [N] when the needle 103 penetrates the nonwoven fabric 30, W NWF is the total basis weight of nonwoven fabric 30 (g / m 2 ), N NDL is the number of needles 103.

[0043] The penetration resistance of the nonwoven fabric 30 as described above can be appropriately changed by changing the material and fineness of the fibers constituting the nonwoven fabric, the density of the nonwoven fabric, the form of the nonwoven fabric, the manufacturing method, and the like.

[0044] The fiber material constituting the nonwoven fabric 30 is not particularly limited, and in addition to the materials listed as the short fiber materials of the first batt layer 20, examples include cellulosic fibers such as rayon, polynosic, lyocell, cupra, cellulose nanofiber, cotton, and hemp, and hydrophilic fibers such as silk and wool, and one of these can be used alone or two or more can be used in combination.

[0045] Among the above, it is preferable that the fibers constituting the nonwoven fabric 30 contain hydrophilic fibers. When the nonwoven fabric 30 contains hydrophilic fibers, the nonwoven fabric 30 can easily retain moisture, and as a result, the rewetting phenomenon after pressing can be more suitably suppressed.

[0046] The hydrophilic fibers may be fibers with an official moisture regain of 4.0% or more, preferably 5.0% or more, such as nylon 4.5%, rayon 11.0%, polynosic 11.0%, lyocell 13.0%, cupra 11.0%, cotton 8.5%, linen 12.0%, silk 12.0%, and wool 13.0%.

[0047] The official moisture regain of the hydrophilic fibers is more preferably 8.0% or more, and particularly preferably 10.0% or more, which allows the nonwoven fabric 30 to retain moisture more easily, thereby further suppressing rewetting after pressing.

[0048] Furthermore, the difference between the official moisture regain of the fibers constituting nonwoven fabric 30 and the official moisture regain of the short fibers constituting first batt layer 20 is not particularly limited, but is, for example, 2.0% to 12%, preferably 4.0% to 10%. In this way, by having an appropriate difference in official moisture regain between the fibers constituting nonwoven fabric 30 and the short fibers constituting first batt layer 20, moisture transferred to first batt layer 20 through nonwoven fabric 30 during pressing is efficiently discharged to substrate 10 and then to the outside of papermaking felt 1.

[0049] Furthermore, the difference between the official moisture regain of the fibers constituting the nonwoven fabric 30 and the official moisture regain of the short fibers constituting the second batt layer 40 is not particularly limited, but is, for example, 2.0% to 12%, preferably 4.0% to 10%. In this way, if there is an appropriate difference in the official moisture regain between the fibers constituting the nonwoven fabric 30 and the short fibers constituting the second batt layer 40, the nonwoven fabric 30 will be able to retain moisture more easily when negative pressure is generated in the papermaking felt 1 immediately after pressing, and rewetting will be more reliably suppressed.

[0050] Among the above-mentioned fibers, the fibers constituting the nonwoven fabric 30 preferably include one or more fibers selected from nylon, cupra, rayon, lyocell, silk, linen, and wool, and more preferably one or more fibers selected from cupra, rayon, lyocell, silk, linen, and wool. Nylon has moderate hydrophilicity and excellent strength. Other preferred fibers have moderate strength and excellent hydrophilicity.

[0051] The fibers constituting the nonwoven fabric 30 can be short fiber yarns (200 mm or less), long fiber yarns (more than 200 mm and less than 15,000 mm), or continuous yarns. Of the above, the fibers constituting the nonwoven fabric 30 preferably include long fiber yarns and / or continuous yarns, and more preferably continuous yarns. When the fibers constituting the nonwoven fabric 30 are relatively long and have low penetration resistance, there is little fiber movement in the nonwoven fabric 30 during needle punching, allowing the density of the nonwoven fabric 30 to be maintained at a high level. The continuous yarn referred to here refers to a yarn that is continuously produced in the manufacturing process and ideally has no ends; for example, it is a so-called filament that has ends formed due to process reasons such as cutting the nonwoven fabric 30.

[0052] Furthermore, the fiber diameter of the fibers constituting nonwoven fabric 30, particularly the fiber diameter of the continuous threads, is not particularly limited, but is, for example, 5.0 μm to 30 μm, preferably 10 μm to 25 μm. When the fineness of the fibers constituting nonwoven fabric 30 is equal to or greater than the above-mentioned lower limit, the strength of nonwoven fabric 30 can be ensured while ensuring appropriate water permeability during pressing. When the fineness of the fibers constituting nonwoven fabric 30 is equal to or less than the above-mentioned upper limit, the water retention capacity of nonwoven fabric 30 due to capillary action can be sufficient, allowing smooth transfer of moisture from second batt layer 40 to nonwoven fabric 30 during pressing and suppressing transfer of moisture from nonwoven fabric 30 to second batt layer 40 immediately after pressing.

[0053] The nonwoven fabric 30 can be manufactured by, for example, a dry method, a wet method, a spunbond method, a meltblown method, etc. Among the above methods, the nonwoven fabric 30 is preferably a spunbond nonwoven fabric manufactured by the spunbond method. The spunbond method allows the nonwoven fabric 30 to be manufactured using continuous yarns.

[0054] Furthermore, the nonwoven fabric 30 may be processed by a processing method such as a thermal bonding method, a chemical bonding method, a needle punching method, a hydroentanglement method (spunlace), etc. By processing by these methods, the penetration resistance of the nonwoven fabric 30 can be adjusted.

[0055] The basis weight of the nonwoven fabric 30 is not particularly limited, but is, for example, 10 g / m 2 More than 100g / m 2 Less than 15 g / m 2 More than 60g / m 2 Less than 20 g / m, more preferably 2 More than 50g / m 2 This allows the nonwoven fabric 30 to function adequately as a barrier layer for suppressing rewetting while ensuring appropriate air permeability. Note that, in order to adjust the basis weight of the nonwoven fabric 30, for example, multiple nonwoven fabrics may be prepared and stacked to form a single layer of nonwoven fabric 30 so as to achieve the desired basis weight.

[0056] The second batt layer 40 is a layer made of short fibers and provided adjacent to the nonwoven fabric 30 on the wet paper web support surface 41 side of the nonwoven fabric 30. The second batt layer 40 is arranged together with the first batt layer 20, sandwiching the nonwoven fabric 30. The second batt layer 40 is also located as the outermost layer of the papermaking felt 1, and forms the wet paper web support surface 41 for supporting the wet paper web.

[0057] The material of the staple fibers (second staple fibers) constituting the second batt layer 40 is not particularly limited, and may be the same as the materials constituting the first batt layer 40, and one of these may be used alone or two or more may be used in combination. From the viewpoints of abrasion resistance, compression recovery, impact resistance, hydrophilicity, hydrolysis resistance, chemical resistance, etc., polyamide is preferred as the material of the staple fibers.

[0058] The fineness of the second short fibers constituting the second batt layer 40 is not particularly limited, but may be, for example, The dtex is 0.1 dtex or more and 200 dtex or less, preferably 2.0 dtex or more and 70 dtex or less, and more preferably 2.0 dtex or more and 30 dtex or less. This ensures sufficient strength of the second batt layer 40, sufficient smoothness of the wet paper web support surface 41, and sufficient moisture absorption from the wet paper web by capillary action due to the fine second short fibers.

[0059] The basis weight of the second batt layer 40 is not particularly limited, but is, for example, 50 g / m 2 More than 800g / m 2 Less than 50 g / m 2 More than 700g / m 2 Less than 50 g / m 2 More than 600g / m 2 This allows an appropriate amount of space to be maintained for absorbing water under pressure.

[0060] The total weight of the first batt layer 20 and the second batt layer 40 is 100 g / m 2 More than 1,600g / m 2 Preferably 100 g / m or less 2 More than 1,400g / m 2 or less, more preferably 100 g / m 2 More than 1,200g / m 2 The total basis weight of the first batt layer 20 and the second batt layer 40 is appropriately set depending on the desired properties of the papermaking felt 1, such as strength, porosity, and breathability.

[0061] The third batt layer 50 is a layer made of short fibers and provided adjacent to the substrate 10 on the roll contact surface 51 side of the substrate 10. The third batt layer 50 is located as the outermost layer of the papermaking felt 1 and forms the roll contact surface 51 that comes into contact with the roll. The papermaking felt 1 is not limited to the embodiment shown in the drawings, and may also be configured without the third batt layer 50.

[0062] The material of the staple fibers (third staple fibers) constituting the third batt layer 50 is not particularly limited, and may be the same as the materials constituting the first batt layer 20. One of these may be used alone or two or more may be used in combination. From the viewpoints of abrasion resistance, compression recovery, impact resistance, hydrophilicity, hydrolysis resistance, chemical resistance, etc., polyamide is preferred as the material of the staple fibers.

[0063] The fineness of the third staple fibers constituting the third batt layer 50 is not particularly limited, but may be, for example, 3.0 dtex to 150 dtex, preferably 6.0 dtex to 100 dtex, and more preferably 10 dtex to 70 dtex, which allows the third batt layer 50 to have sufficient strength and abrasion resistance.

[0064] The basis weight of the third batt layer 50 is not particularly limited, but is, for example, 50 g / m 2 More than 200g / m 2 This allows an appropriate amount of space to be maintained for absorbing water under pressure.

[0065] The weight of the papermaking felt 1 is not particularly limited, but for example, it is 250 g / m 2 More than 3000g / m 2 Preferably, 400 g / m or less 2 More than 2000g / m 2 The thickness of the papermaking felt 1 is not particularly limited, but is, for example, 1.0 mm or more and 6.0 mm or less, and preferably 2.0 mm or more and 4.0 mm or less.

[0066] The configuration of the papermaking felt 1 has been described above. As described above, the papermaking felt 1 according to this embodiment can suppress the rewetting phenomenon of a wet paper web and sufficiently reduce the moisture content of the wet paper web after pressing. Specifically, this can be explained as follows with reference to FIG. 3. FIG. 3 is a schematic diagram for explaining the behavior of the papermaking felt and wet paper web before and after pressing according to this embodiment. Note that, although the figure illustrates a single-felt press roll mechanism as an example of the press device, the same explanation can be applied to a single-felt or double-felt shoe press mechanism, or a double-felt press roll mechanism.

[0067] 3, in the press part, the papermaking felt 1 carries the wet paper W on its wet paper support surface 41, travels along the machine direction MD, and passes through a press mechanism consisting of press rolls 200A and 200B. At this time, in a region 201 before entering the press mechanism, the wet paper W and the papermaking felt 1 are not subjected to pressure in the thickness direction.

[0068] Next, in the press region 203 where the wet paper web W and papermaking felt 1 enter the press mechanism, the wet paper web W and papermaking felt 1 are pressured 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, as the wet paper web W is compressed in the thickness direction, some of the moisture contained in the wet paper web W migrates from the wet paper support surface 41 to the papermaking felt 1, and most of this is discharged from the papermaking felt 1 by the press roll 200B if 202B is a suction roll, or discharged as splash SP from the roll contact surface 51 on the region 205 side if 202B is a plain roll. Alternatively, it is discharged from the roll contact surface 51 on the region 201 side. On the other hand, the portion of the moisture that has migrated to the papermaking felt 1 and is not discharged remains in the papermaking felt 1.

[0069] Next, in region 205 where the wet paper W and the papermaking felt 1 have left the press mechanism, the wet paper W and the papermaking felt 1 are released from the pressure of the press rolls 200A and 200B and suddenly expand. At this time, negative pressure is generated in the wet paper W and the papermaking felt 1, and they begin to absorb the surrounding air and moisture.

[0070] Here, focusing on the relationship between the wet paper web W and the papermaking felt 1, when negative pressure is generated in the wet paper web W, the wet paper web W begins to absorb air and moisture in the papermaking felt 1 (rewetting phenomenon). However, in the papermaking felt 1 according to this embodiment, the nonwoven fabric 30 is disposed between the first batt layer 20 and the second batt layer 40. The nonwoven fabric 30 has a sufficiently low needle penetration resistance, 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 nonwoven fabric 30 prevents the moisture M present on the roll contact surface 51 side of the nonwoven fabric 30 of the papermaking felt 1 from migrating toward the wet paper web support surface 41 side, and only a portion of the moisture M moves to the second batt layer 40. In this way, the nonwoven fabric 30 prevents the migration of moisture M, thereby suppressing the rewetting phenomenon of the wet paper web W.

[0071] In particular, since the nonwoven fabric 30 contains hydrophilic fibers, the nonwoven fabric 30 has a greater ability to retain moisture M, and the migration of moisture M to the second batt layer 40 side is further suppressed. Furthermore, in this embodiment, the second batt layer 40 is arranged closer to the wet paper web support surface 41 than the nonwoven fabric 30. This allows the second batt layer 40 to have functions such as smoothness of the wet paper web support surface 41 and adhesion to the wet paper web W, while the nonwoven fabric 30 can be configured specifically for the function of suppressing the migration of moisture M. This allows each function of the papermaking felt 1 to be fully exerted, and the papermaking felt 1's effect of suppressing the rewetting phenomenon is further enhanced.

[0072] Furthermore, in this embodiment, the nonwoven fabric 30 is disposed between the first batt layer 20 and the second batt layer 40 on the wet paper web support surface 41 side of the substrate 10, i.e., between the batt layers on the wet paper web support surface 41 side of the substrate 10. This allows the volume of the papermaking felt 1 on the roll contact surface 51 side to be relatively larger than that of the nonwoven fabric 30, and the nonwoven fabric 30 can function as a barrier layer for the larger amount of moisture in that portion. As a result, the rewetting suppression effect of the papermaking felt 1 is further enhanced. As described above, the papermaking felt 1 can suppress the rewetting phenomenon of the wet paper and can sufficiently reduce the moisture content of the wet paper after pressing.

[0073] <3. Modifications> Next, several modified examples of the papermaking felt according to the above-described embodiment will be described. Below, differences from the above-described embodiment will be mainly described, and similar points will not be described. Furthermore, the modified examples described below and the features of the above-described embodiment may be applied independently, or two or more of them may be applied in combination as long as it is technically permissible.

[0074] (3.1. First Modification)

[0075] Fig. 4 is a machine direction cross-sectional view showing a papermaking felt according to a modified example of the present invention. The papermaking felt 1A shown in Fig. 4 has a substrate 10, a first batt layer 20A, a nonwoven fabric 30A, and a third batt layer 50, and the second batt layer 40 is omitted. Furthermore, the nonwoven fabric 30A is disposed between the first batt layer 20A and the substrate 10. This papermaking felt 1A can also effectively suppress rewetting.

[0076] (3.2. Second Variation)

[0077] In the above-described embodiment, the papermaking felt 1 has been described as having an endless shape, but the present invention is not limited to this. The papermaking felt according to the present invention may be a belt-shaped felt with an endless shape. In this case, seam loops are provided at both ends of the papermaking felt in the machine direction. The seam loops at both ends are then interlocked with each other and a core wire is inserted into the seam loops to form a ring-shaped (endless) papermaking felt, which is then mounted on a papermaking machine.

[0078] <4. Manufacturing method of papermaking felt> Finally, a method for manufacturing a papermaking felt according to a preferred embodiment of the present invention will be described. The method for manufacturing a papermaking felt according to the present invention comprises the steps of laminating a nonwoven fabric and staple fibers on one surface of a substrate, and then needle-punching the laminate to form a batt layer made of the nonwoven fabric and the staple fibers on the one surface of the substrate, and the nonwoven fabric has a basis weight of 100 g / m. 2 -Penetration resistance per needle is 2.0N / (100g / m 2 The following describes an example of a method for producing the papermaking felt 1 shown in FIG.

[0079] First, the substrate 10 is prepared. Next, short fiber cards for the first batt layer 20, nonwoven fabric 30, second short fiber cards for the second batt layer 40, and short fiber cards for the third batt layer 50 are prepared. Next, these cards and nonwoven fabric 30 are layered together with the substrate 10. In this case, the cards, substrate 10, and nonwoven fabric 30 are layered so that the layers of the papermaking felt 1 are formed in the following order: third batt layer 50, substrate 10, first batt layer 20, nonwoven fabric 30, and second batt layer 40. In this case, the number of cards and nonwoven fabric 30 may be adjusted to achieve the required basis weight.

[0080] Next, needle-punching is carried out to entangle and integrate the cards, nonwoven fabric 30, and substrate 10, thereby obtaining a precursor of the papermaking felt 1. In the present embodiment, it has been described that all of the cards, nonwoven fabric 30, and substrate 10 are simultaneously stacked and needle-punched all at once, but it is also possible to stack cards layer by layer on the substrate 10 and then needle-punch them, and repeat this process to stack and integrate the layers.

[0081] As described above, the nonwoven fabric 30 has a relatively small penetration resistance. Therefore, the fibers of the nonwoven fabric 30 are prevented from dispersing in the thickness direction during needle punching, and the density of the nonwoven fabric 30 is maintained at a relatively high level. As a result, the nonwoven fabric 30 can effectively prevent the rewetting of wet paper even in the papermaking felt 1.

[0082] Finally, the precursor of the papermaking felt 1 is subjected to chemical treatment, heat setting, press processing, etc. as required to obtain the papermaking felt 1.

[0083] Although the present invention has been described in detail above based on the preferred embodiment, the present invention is not limited to this. Each component may be replaced with any other component that can perform a similar function, or , any configuration can be added. [Example]

[0084] The present invention will be explained in more detail below with reference to examples, but the present invention is not limited to these examples.

[0085] <1. Manufacturing of papermaking felt> First, a woven fabric having the following structure was prepared as a substrate. Warp: Two 330dtex nylon monofilaments twisted together Two more twisted strands Weft: Two 330dtex nylon monofilaments twisted together Three more twisted strands Weave: 31 twill (twill, four-way twill (3 / 1)), warp threads 44 / 5cm, weft threads 40 / 5cm Weight: 400g / m 2

[0086] Next, short fiber cards and nonwoven fabrics corresponding to the following layers were prepared. First batt layer: Nylon 6 staple fiber, fineness 22 dtex, basis weight 400 g / m 2 , Official moisture content 4.5% Second batt layer: Nylon 6 staple fiber, fineness 22 dtex, basis weight 100 g / m 2 , Official moisture content 4.5% Third batt layer: Nylon 6 staple fiber, fineness 22 dtex, basis weight 100 g / m 2 , Official moisture content 4.5%

[0087] In Examples 1 to 4, a cupra nonwoven fabric (official moisture regain 11%, basis weight 20 g / m 2 The number of sheets was adjusted according to the required basis weight using a spunbond nonwoven fabric (fiber diameter 20 μm, processed by water jet (hydroentanglement method)). In Examples 4 to 8, a rayon nonwoven fabric (official moisture regain 11%, basis weight 20 g / m 2 The number of sheets was adjusted according to the required basis weight. In Examples 9 to 12, a lyocell nonwoven fabric (official moisture regain 13%, basis weight 20 g / m 2 The number of sheets was adjusted according to the required basis weight. In Examples 13 to 15, nylon nonwoven fabric (official moisture regain 4.5%, basis weight 20 g / m 2 The number of sheets was adjusted according to the required basis weight.

[0088] Next, the card for the third batt layer, the substrate, the first batt layer, and the second batt layer were laminated in this order, and then needle-punched to produce the papermaking felts of Examples 1 to 15 and Comparative Example. The needle punch density was 4000 times / inch. 2(surface 3000 times / inch 2 , rear surface 1000 times / inch 2 ).

[0089] <2. Evaluation> (1) Penetration resistance of nonwoven fabric The needle penetration resistance was measured for each of the nonwoven fabrics used in Examples 1 to 15. The penetration resistance was measured by a compression test using a tensile tester shown in Fig. 2. Specifically, several sheets of nonwoven fabric 30 sandwiched between fixing plates 109 were fixed to a jig 101B. Here, the nonwoven fabric 30 had a basis weight of 100 g / m 2 The number of layers was adjusted so that the thickness was approximately 1 / 2.

[0090] With the nonwoven fabric 30 fixed in this manner, the needle 103 was moved toward the nonwoven fabric 30 using a tensile tester, and the first barb of the needle was penetrated into the nonwoven fabric 30. The maximum value of the resistance force applied to the needle 103 at this time was defined as the penetration resistance. The number of needles was 54, and the needle-planted area was 602 cm. 2 , needle density is 0.090 / cm 2 The moving speed of the needle 103 was 200 mm / min. The needle used had a needle count of 32, a point diameter of 0.08 mm, a point-to-first barb distance of 6.35 mm, a barb depth of 0.09 mm, a kick-up of 0.01 mm, and a barb length of 0.5 mm.

[0091] The penetration resistance obtained as described above was measured for a nonwoven fabric 30 having a basis weight of 100 g / m 2 The weight of the nonwoven fabric 30 is calculated so that the number of needles 103 is one. 2 The penetration resistance per needle was calculated using the following formula (1).

[0092] R=R T ÷W NWF ×100÷N NDL (Formula 1) Here, R is the basis weight of the nonwoven fabric 30 (100 g / m 2 -Penetration resistance per needle [N / (100g / m2 ·Book)], R T is the maximum resistance force [N] when the needle 103 penetrates the nonwoven fabric 30, W NWF is the total basis weight of nonwoven fabric 30 (g / m 2 ), N NDL is the number of needles 103.

[0093] (2) Water squeezeability The papermaking felts according to Examples 1 to 15 and Comparative Example were evaluated for water squeezing ability by the following method: Figure 5 is a schematic diagram for explaining the method of the water squeezing test.

[0094] As shown in Fig. 5, first, the papermaking felts F according to Examples 1 to 15 and Comparative Example, cut to a diameter of 7 cm, were placed on a metal base 301, and the moisture content of the papermaking felts F was adjusted to 30%. Here, the moisture content refers to the total mass of the papermaking felt and water divided by the mass of the water.

[0095] Next, three sheets of toilet paper were stacked as a model of wet paper and wetted with water to adjust the moisture content to 80%. The moisture content is calculated by dividing the mass of the water by the total mass of the toilet paper and water. This was cut into a piece with a diameter of 6 cm to form wet paper W, which was placed on papermaking felt F. The dry weight of the wet paper W was 0.136 g, and the moisture content of the wet paper W was 0.544 g.

[0096] Next, a metal top plate 302 (6 kg) was dropped from 20 cm above the wet paper W to press it. The pressure at this time was 50 kg / cm. 2 The top plate 302 was adjusted so that it would bounce back and move upward after colliding with the wet paper web W. Therefore, the test was carried out so that the top plate 302 was fixed at the point when the top plate 302 moved upward after the first press to prevent a second press from being performed.

[0097] The mass of the wet paper W after pressing, the moisture content in the wet paper W obtained by subtracting the dry weight of the wet paper W from the weight of the wet paper W, and the moisture content of the wet paper W after pressing were calculated from the dry weight of the wet paper W, and the value obtained by subtracting the moisture content of the wet paper W after pressing from 100 was calculated as the dryness ΔK (%). In this evaluation, dryness ΔK (%) represents the degree of moisture content reduction due to pressing. It is generally known that a 1% reduction in the moisture content of the wet paper in the press part can reduce the energy required for drying in the subsequent dryer part by approximately 4%. The obtained dryness ΔK (%) and the estimated possible drying energy reduction from comparative examples based on this are shown in Table 1.

[0098] [Table 1]

[0099] As shown in Table 1, the papermaking felts according to Examples 1 to 15 are significantly better at squeezing water during pressing than the papermaking felts according to the comparative examples, and it was shown that rewetting is effectively suppressed when the papermaking felts according to Examples 1 to 15 are used. It was also suggested that the use of the papermaking felts according to Examples 1 to 15 makes it possible to significantly reduce the drying energy required in the dryer part subsequent to the press part.

[0100] Furthermore, when Examples 13 to 15 are compared with Examples 5 to 8, the penetration resistance of the nonwoven fabrics used therein is about the same, but when compared at the same basis weight, the papermaking felts of Examples 5 to 8 have significantly better water-squeezing ability. This is thought to be because the official moisture regain of the fibers constituting the nonwoven fabric is significantly higher in the rayon fibers of Examples 5 to 8, and therefore the nonwoven fabric in the papermaking felt retains moisture and suppresses rewetting.

[0101] It has been observed that the dryness tends to improve as the basis weight of the nonwoven fabric increases. However, if the basis weight of the nonwoven fabric is too high, the wet paper may break depending on the type and basis weight of the wet paper. Therefore, it is necessary to select a nonwoven fabric with an appropriate basis weight for an actual papermaking machine. [Explanation of symbols]

[0102] 1, 1A, 1B Papermaking felt 10 Base material 20, 20A, 20B First batt layer 30, 30A, 30B non-woven fabric 40 Second Bat Layer 41 Wet paper support surface 50 Third Bat Layer 51 Roll contact surface

Claims

1. A papermaking felt having a wet paper support surface for supporting a wet paper, A substrate; a batt layer that is arranged on the wet paper support surface side of the substrate and that contains short fibers; a nonwoven fabric disposed adjacent to the batt layer on the wet paper web bearing surface side of the substrate, The nonwoven fabric has a basis weight of 100 g / m ２ -Penetration resistance per needle is 2.0 N / (100 g / m ２ ・Book) Papermaking felt.

2. 2. The papermaking felt of claim 1, wherein the nonwoven fabric comprises continuous yarns.

3. 2. The papermaking felt according to claim 1, wherein the nonwoven fabric contains hydrophilic fibers having an official moisture regain of 10.0% or more.

4. 4. The papermaking felt according to claim 3, wherein the hydrophilic fibers include one or more selected from the group consisting of cupro, rayon, lyocell, silk, hemp, and wool.

5. 2. The papermaking felt according to claim 1, wherein the fiber diameter of the fibers constituting the nonwoven fabric is 5.0 μm or more and 30 μm or less.

6. 2. The papermaking felt according to claim 1, wherein the nonwoven fabric is a spunbond nonwoven fabric.

7. The papermaking felt according to claim 1, wherein the batt layer is in contact with the nonwoven fabric and is disposed closer to the substrate than the nonwoven fabric.

8. Further, the second batt layer is disposed on the wet paper support surface side of the substrate and is configured to contain second short fibers, The papermaking felt according to claim 1 , wherein the batt layer and the second batt layer are arranged with the nonwoven fabric sandwiched between them.

9. 2. The papermaking felt according to claim 1, wherein the difference between the official moisture regain of the fibers constituting said nonwoven fabric and the official moisture regain of said short fibers is 2.0% or more and 12% or less.

10. 9. The papermaking felt according to claim 8, wherein the difference between the official moisture regain of the fibers constituting the nonwoven fabric and the official moisture regain of the second short fibers is 2.0% or more and 12% or less.

11. 2. The papermaking felt according to claim 1, wherein the fineness of the short fibers is 2.0 dtex or more and 70 dtex or less.

12. 9. The papermaking felt according to claim 8, wherein the fineness of the second short fibers is 2.0 dtex or more and 70 dtex or less.

13. a step of laminating a nonwoven fabric and staple fibers on one surface of a substrate and performing a needle punching process to form a batt layer made of the nonwoven fabric and the staple fibers on the one surface of the substrate, The nonwoven fabric has a basis weight of 100 g / m ２ -Penetration resistance per needle is 2.0 N / (100 g / m ２ ・This) A method for manufacturing papermaking felt.

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