Paper making fabric and manufacturing method thereof

Abstract

To provide a paper making wire with further improved abrasion resistance while suppressing decrease in other performances such as dewaterability and a manufacturing method thereof.SOLUTION: A paper making wire 1 comprises one or a plurality of layers including a running surface side layer 2 arranged in the most running surface side. The running surface side layer 2 includes a warp 4 and a weft 5 interwoven with each other. The weft 5 includes a polyester yarn comprising polyethylene terephthalate as the main component. The polyethylene terephthalate has a crystallinity of 22-32%. A tensile storage modulus of the weft 5 at 180°C is 0.19-0.28 GPa. The polyester yarn may further include 20-32 wt.% of a polyester elastomer and 1-4 wt.% of a carbodiimide.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a papermaking fabric (wire) used to transport and dewater paper stock in the wire part of a papermaking machine, where the paper stock is first dewatered and then a paper layer is formed, and a method for manufacturing the same. [Background technology]

[0002] As papermaking wires travel over the suction box and suction rolls of a papermaking machine, they are sucked in to dehydrate the paper stock. This creates a large resistance on the wire, causing wear on the running surface. For this reason, papermaking wires reach the end of their life after a certain distance traveled and are replaced. Reducing the replacement cycle reduces workload and costs, so there is a demand for improved wear resistance in papermaking wires.

[0003] Polyamide yarns and polyester yarns are used as the warp and weft of papermaking wires. Papermaking wires using polyester yarns have better dimensional stability but poorer abrasion resistance than papermaking wires using polyamide yarns. Therefore, various methods have been proposed to improve the abrasion resistance of polyester yarns themselves and / or the abrasion resistance of papermaking wires using polyester yarns (e.g., Patent Documents 1 to 5). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Special Publication No. 2017-520691 [Patent Document 2] Japanese Patent Application Laid-Open No. 2007-247131 [Patent Document 3] Japanese Patent Application Laid-Open No. 2011-084596 [Patent Document 4] Japanese Patent Application Laid-Open No. 2013-119689 [Patent Document 5] Japanese Patent Application Laid-Open No. 2008-240228 Summary of the Invention [Problem to be solved by the invention]

[0005] However, further improvement in abrasion resistance is required. In view of the above background, an object of the present invention is to provide a papermaking wire having further improved abrasion resistance while suppressing deterioration in other performances such as dimensional stability and drainage ability, and a method for producing the same. [Means for solving the problem]

[0006] The terms used in this specification and claims are explained below. "Weave" refers to the way in which warp and weft threads intertwine. With respect to warp and weft threads, the papermaking side is referred to as "upper" and the running side as "lower." The "warp direction" is the direction in which the warp threads extend, roughly corresponding to the length direction (machine direction (MD)) of the papermaking wire, and the "weft direction" is the direction in which the weft threads extend, roughly corresponding to the width direction (cross-machine direction (CMD)) of the papermaking wire. The "warp cross section" is a cross section parallel to the thickness direction and warp direction of the papermaking wire, and the "weft cross section" is a cross section parallel to the thickness direction and weft direction of the papermaking wire.

[0007] In order to solve the above problems, one aspect of the present invention is a papermaking fabric (1) composed of one or more layers including a running surface side layer (2) arranged closest to the running surface, wherein the running surface side layer includes warp yarns (lower warp yarns 4) and weft yarns (lower weft yarns 5) woven together, the weft yarns of the running surface side layer including polyester yarns whose main component is polyethylene terephthalate, the degree of crystallinity of the polyethylene terephthalate being 22% to 32% relative to the total amount of the polyethylene terephthalate, and the storage modulus at 180°C of the polyester yarns being 0.19 GPa to 0.28 GPa.

[0008] According to this embodiment, since the weft yarn components, crystallinity, and 180°C storage modulus are within predetermined ranges, a papermaking fabric can be provided that has further improved abrasion resistance while suppressing deterioration of other performance such as dimensional stability and dewatering properties.

[0009] In the above aspect, the tensile modulus of the polyester yarn at 20°C is preferably 4.8 GPa to 5.3 GPa.

[0010] According to this embodiment, the polyester weft yarn has an appropriate hardness, so that wear during travel through the suction box is suppressed, and a papermaking fabric having an appropriate rigidity can be obtained.

[0011] In the above embodiment, the polyester yarn of the weft yarn (5) of the running surface side layer (2) preferably further contains a polyester elastomer in an amount of 20% to 32% by weight.

[0012] According to this embodiment, the polyester elastomer prevents the weft yarn from being excessively flattened, thereby suppressing a decrease in drainage, and further improving abrasion resistance. In addition, the carbodiimide suppresses hydrolysis of the polyester yarn and improves the compatibility between polyethylene terephthalate and the polyester-based thermoplastic elastomer, thereby enabling the production of weft yarns with high abrasion resistance and uniform diameter.

[0013] In the above embodiment, the polyester yarn of the weft yarn (5) of the running surface side layer (2) preferably further contains 1% by weight to 4% by weight of carbodiimide.

[0014] According to this embodiment, the hydrolysis of the polyester yarn is suppressed by the carbodiimide, and the compatibility between the polyethylene terephthalate and the polyester-based thermoplastic elastomer is improved, so that a weft yarn having high abrasion resistance and a uniform diameter can be obtained.

[0015] In the above embodiment, the 180°C tensile storage modulus of the polyester yarn of the weft yarn (5) of the running surface side layer (2) is preferably smaller than the 180°C tensile storage modulus of the warp yarn (4) of the running surface side layer (2).

[0016] According to this aspect, during heat setting, the warp yarns that are lifting the weft yarns can be prevented from being pushed down toward the thickness direction running surface by the weft yarns, thereby preventing a decrease in the abrasion resistance of the papermaking fabric.

[0017] One aspect of the present invention is a method for producing a papermaking fabric (1) having one or more layers in which warp and weft yarns are woven together and which includes a running surface side layer (2) arranged closest to the running surface, the method comprising the steps of weaving the one or more layers using polyester yarn having a crystallinity of 22% to 32% for the weft yarn (5) of the running surface side layer (2), and applying tension to the woven one or more layers while heating the one or more woven layers at a temperature at which the tensile storage modulus of the polyester yarn is 0.19 to 0.28 GPa.

[0018] According to this embodiment, the components, crystallinity, and tensile storage modulus of the weft yarn exposed to the running surface are within predetermined ranges, so that a method for producing a papermaking fabric with improved abrasion resistance can be provided while suppressing deterioration in other performance such as dimensional stability and drainage. [Effects of the Invention]

[0019] According to the above-described aspects, it is possible to provide a papermaking fabric and a method for producing the same that have improved abrasion resistance while suppressing deterioration in other performances such as drainage. [Brief explanation of the drawings]

[0020] [Figure 1] Photograph of the weft cross section (cross section parallel to the weft and thickness directions) of the papermaking wire according to the embodiment [Figure 2] Schematic diagram of the weft cross section (A: Papermaking wire according to the embodiment, B: Conventional papermaking wire) [Figure 3] Graph showing the relationship between polyester elastomer ratio, wear rate, and breathability [Figure 4] Graph comparing the crystallinity, wear rate, 180°C storage modulus, and tensile modulus of the examples and comparative examples. DETAILED DESCRIPTION OF THE INVENTION

[0021] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. Fig. 1 shows a papermaking wire 1 according to the embodiment. The papermaking wire 1 is used in the wire part of a papermaking machine. The papermaking wire 1 comprises a running surface side layer 2 arranged on the running surface side and a papermaking surface side layer 3 arranged on the papermaking surface side.

[0022] The running surface side layer 2 includes lower warp yarns 4 and lower weft yarns 5 woven together, and the papermaking surface side layer 3 includes upper warp yarns 6 and upper weft yarns 7 woven together. The running surface side layer 2 and the papermaking surface side layer 3 are bound together by weft self-binding yarns 8, which are woven into the lower warp yarns 4 to form the design of the running surface side layer 2 and which are woven into the upper warp yarns 6 to form the design of the papermaking surface side layer 3.

[0023] In the running surface side layer 2, the lower weft 5 is woven into the lower warp 4 so that it passes over one lower warp 4 and then under five consecutive lower warps 4, repeatedly. Two adjacent lower wefts 5 pass over the lower warp 4 with a shift of three lower warps 4 from each other. When looking at the weft cross section in a predetermined section in the weft direction, the underside of the lowest lower weft 5 in that section is located below the underside of the lowest lower warp 4 in that section, so that the lower weft 5 wears out before the lower warp 4. The papermaking surface side layer 3 forms a plain weave. The weave of the papermaking wire 1 is not limited to that formed by such a weave. For example, the lower weft 5 may pass under six or more or four or fewer consecutive lower warps 4, and the papermaking surface side layer 3 may be formed with a twill weave.

[0024] The materials constituting the lower warp 4, upper warp 6, and upper weft 7 are not particularly limited, but polyamide-based resins and polyester-based resins are preferred. The polyamide-based resin is preferably an aliphatic polyamide resin, and nylon is more preferred. Examples of nylon include nylon 66, nylon 6, nylon 12, nylon 11, nylon 610, and nylon 612. These may be used alone or in combination of two or more. The polyester-based resin is not particularly limited as long as it is a polyester composed of a dicarboxylic acid and a glycol, and may be polyethylene terephthalate (PET), polypropylene terephthalate, polybutylene terephthalate (PBT), polyethylene naphthalate, etc. These may be used alone or in combination of two or more. The lower warp 4, upper warp 6, and upper weft 7 may be made of the same material or different materials. Each thread may be made of a single material or two or more different materials. Furthermore, each thread may contain an inorganic filler and / or an organic filler. The material constituting the weft self-binding yarn 8 is not particularly limited, but it is preferably the same as the lower weft yarn 5 described below.

[0025] The lower weft 5 of the running side layer 2 (the weft at least a portion of which is exposed on the running side surface of the papermaking wire 1) has the following characteristics in terms of tensile storage modulus and crystallinity. The lower weft 5 is a polyester yarn whose main component is polyethylene terephthalate. The 180°C tensile storage modulus of the lower weft 5, i.e., the modulus of elasticity in a tensile storage state at approximately 180°C, is 0.19 GPa to 0.28 GPa (X to Y are referred to as "X to Y"; the same applies hereinafter). The crystallinity of the polyethylene terephthalate in the lower weft 5 is 22% to 32% of the total amount of polyethylene terephthalate in the lower weft 5.

[0026] The manufacturing process of the papermaking wire 1 includes a step (heat setting) for stabilizing the dimensions of the papermaking wire 1. In heat setting, the endless woven fabric is placed between two tension rolls, and the distance between the two tension rolls is increased to apply tension in the warp and weft directions to the fabric, while the fabric is heated by, for example, blowing hot air onto the fabric. The heating temperature is, for example, 130°C to 200°C, and in this embodiment, the fabric is heated to 180°C. Note that, instead of the lower weft 5 having a 180°C tensile storage modulus of 0.19 GPa to 0.28 GPa, tension may be applied to the lower weft 5 while heating it at a temperature at which the tensile storage modulus is 0.19 to 0.28 GPa during heat setting.

[0027] Furthermore, when wires are used in a paper machine, a large tension is applied in the warp direction, and damage to the warp threads can lead to wire breakage (ring breakage), so it is necessary to prevent damage to the warp threads.

[0028] Here, by having a tensile storage modulus of 0.19 GPa to 0.28 GPa during heat setting, the lower weft 5 of the running surface side layer 2 becomes moderately easy to deform, and the shape of the lower weft 5 (the weft in contact with the tension roll) exposed to the running surface can be shaped so that it extends more parallel to the running surface without forming a large angle with respect to the running surface (see Figure 2(A)). In other words, the volume of the lower weft 5 located closer to the running surface in the thickness direction than the underside of the lower warp 4 exposed to the running surface (which wears before the lower warp 4) can be increased, thereby increasing the contact area between the lower weft 5 and the running surface. By shaping the lower weft 5 in this way, stress on the lower weft 5 is dispersed, further slowing the wear rate of the lower weft 5 and extending the life of the papermaking wire 1 (improving the wear resistance of the papermaking wire 1).

[0029] On the other hand, the lower weft 5 of the running surface side layer 2 has the above-mentioned tensile storage modulus, so that it is not easily deformed during heat setting, and the intersection points between the lower warp 4 and the lower weft 5 on the running surface side are not excessively flattened. As a result, the mesh of the papermaking wire 1 is prevented from being blocked, and the drainage properties of the wire are maintained.

[0030] If the 180°C tensile storage modulus of the lower weft 5 is less than 0.19 GPa, the lower weft 5 will be excessively flattened at the intersection of the lower warp 4 and the lower weft 5, resulting in smaller mesh and reduced drainage of the papermaking wire 1. If the 180°C tensile storage modulus of the lower weft 5 is greater than 0.28 GPa, the bends of the lower weft 5 passing under the lower warp 4 will be less flattened, reducing the volume of the portion of the lower weft 5 that wears before the lower warp 4, reducing the wear resistance of the papermaking wire 1. If the 180°C tensile storage modulus of the lower weft 5 is 0.19 GPa to 0.28 GPa, the wear resistance of the papermaking wire 1 can be improved while preventing a decrease in drainage of the papermaking wire 1.

[0031] Furthermore, the crystallinity of the polyethylene terephthalate in the lower weft 5 after heat setting is 22% to 32% of the total amount of polyethylene terephthalate in the lower weft 5. By setting the crystallinity of the polyethylene terephthalate in the lower weft 5 of the running surface side layer 2 within this range, the texture does not develop too much in the extending direction of the lower weft 5, so that even if frictional force is applied in a direction perpendicular to the extending direction of the lower weft 5 during use (running) of the papermaking wire 1, the lower weft 5 is less likely to fibrillate, and the abrasion resistance of the lower weft 5 can be improved.

[0032] If the crystallinity of the polyethylene terephthalate in the lower weft 5 is greater than 32%, the fibers in the lower weft 5 will be too fibrillated (the fibers will become fluffy due to friction), making the lower weft 5 vulnerable to abrasion perpendicular to the fiber axis. If the crystallinity of the polyethylene terephthalate in the lower weft 5 is less than 22%, the density of the fiber surface of the lower weft 5 will decrease, making the lower weft 5 vulnerable to abrasion. (In crystals, the molecules are regularly and densely arranged, resulting in strong bonds between them and high abrasion resistance. In amorphous materials, the molecules are irregular and less dense, resulting in weak intermolecular forces and poor abrasion resistance.) By setting the crystallinity of the polyethylene terephthalate to 22% to 32%, the abrasion resistance of the lower weft 5 is improved.

[0033] The lower weft yarn 5 of the running surface side layer 2 has a tensile storage modulus and crystallinity within the above-mentioned ranges, which have a synergistic effect between the shape and surface morphology of the lower weft yarn 5 on the running surface side, thereby improving the abrasion resistance of the papermaking wire 1 without reducing the drainage property or dimensional stability of the papermaking wire 1.

[0034] The tensile modulus of the lower weft 5 at 20°C is preferably 4.8 GPa to 5.3 GPa. If the tensile modulus of the lower weft 5 at 20°C is greater than 5.3 GPa, the yarn becomes stiff, increasing the resistance to snagging when traveling through the suction box and promoting wear. If the tensile modulus of the lower weft 5 at 20°C is less than 4.8 GPa, the lower weft 5 is too soft and the papermaking wire 1 loses the rigidity required as a wire, significantly reducing its performance as a wire. By making the tensile modulus of the lower weft 5 at 20°C 4.8 GPa to 5.3 GPa, the papermaking wire 1 maintains its performance as a wire while improving its wear resistance.

[0035] As long as the tensile storage modulus and crystallinity are within the above-mentioned ranges, the additive components and their ratios of the lower weft 5 are not particularly limited. For example, the lower weft 5 contains 20 to 32% by weight of polyester elastomer and 1 to 4% by weight of carbodiimide. Preferably, the carbodiimide content is 1 to 1.1% by weight. The polyethylene terephthalate content of the lower weft 5 is 64 to 79% by weight.

[0036] Known polyester thermoplastic elastomers can be used as the polyester elastomer. Polyester elastomers are block copolymers, for example, with polyester structures as hard segments in the polymer molecule and polyether or polyester as soft segments. More specifically, they contain a structure comprising structural repeating units derived from, for example, terephthalic acid, ethylene glycol, and polyethylene glycol; from terephthalic acid, butylene glycol, and polyethylene glycol; from terephthalic acid, butylene glycol, and polybutylene glycol; from naphthalenedicarboxylic acid, ethylene glycol, and polyethylene glycol; from naphthalenedicarboxylic acid, butylene glycol, and polyethylene glycol; from naphthalenedicarboxylic acid, butylene glycol, and polybutylene glycol; from terephthalic acid, isophthalic acid, ethylene glycol, and polyethylene glycol; from terephthalic acid, isophthalic acid, butylene glycol, and polyethylene glycol; or from terephthalic acid, isophthalic acid, butylene glycol, and polybutylene glycol. Particularly preferred are those using PBT for the hard segments and polytetramethylene glycol for the soft segments.

[0037] Carbodiimides are added to PET or polyester elastomers by reacting the carbodiimide groups with the terminal ester groups to inhibit hydrolysis and improve compatibility. Therefore, any carbodiimide may be used as long as it has a carbodiimide group, such as a polymer having a carbodiimide group. The monomer of the carbodiimide polymer contains a carbodiimide group and, for example, an aliphatic compound such as a linear alkylene group or an aromatic compound such as an aryl group.

[0038] The 180°C tensile storage modulus of the lower weft 5 is preferably smaller than the 180°C storage modulus of the lower warp 4. By doing so, during heat setting, the lower warp 4, which is lifting the lower weft 5, can be prevented from being pressed down toward the running surface in the thickness direction by the lower weft 5, and a decrease in the abrasion resistance of the papermaking wire 1 can be prevented.

[0039] The papermaking wire 1 is manufactured by an operator performing the following operations. First, the lower warp 4, lower weft 5, upper warp 6, upper weft 7, and weft self-binding yarn 8 are prepared. For the lower weft 5, a polyester yarn having a polyethylene terephthalate crystallinity and a storage modulus at 180°C within the above-mentioned ranges is prepared. Next, these yarns are used to weave a fabric that will become the papermaking wire 1. Next, the fabric is heat-set. In heat-setting, the fabric is heated to 130°C to 200°C, preferably about 180°C, and tension is applied in the warp and weft directions. Heat-setting may be performed at a constant temperature, or the temperature may be increased in stages. In this embodiment, the temperature is increased in stages until it reaches 180°C. In this case, by using polyester yarn with a storage modulus at 180°C of 0.19 GPa to 0.28 GPa as the lower weft 5, the lower weft 5 becomes appropriately soft during heat setting. As a result, the portion of the lower weft 5 located below the lower warp 4 (the portion exposed to the running surface) deforms from the arc shape shown in Figure 2(B) to approach the linear shape shown in Figure 2(A), and remains in this deformed state after heat setting. This increases the contact area between the lower weft 5, which is located closer to the running surface (wears first) than the lower warp 4, which is located closest to the running surface in the thickness direction. As a result, stress on the lower weft 5 during use of the papermaking wire 1 is dispersed, further slowing the wear rate of the lower weft 5 and extending the life of the papermaking wire 1 (improving the wear resistance of the papermaking wire 1).

[0040] As long as the tensile storage modulus and crystallinity are within the above-mentioned predetermined ranges, there are no particular limitations on the additive components and their component ratios of the lower weft 5. For example, by having the polyester elastomer content in the lower weft 5 be 20% by weight to 32% by weight, the lower weft 5 can be prevented from being excessively flattened, thereby suppressing a decrease in drainage, and improving the abrasion resistance of the lower weft 5.

[0041] For example, by setting the carbodiimide content in the lower weft 5 to 1% by weight to 4% by weight, the hydrolysis of PET, which is the main component of the lower weft 5, is further suppressed, and the compatibility between polyethylene terephthalate (PET) and polyester-based thermoplastic elastomer is improved, resulting in a lower weft 5 with high abrasion resistance and a uniform diameter. [Example]

[0042] <Test 1> The crystallinity, abrasion rate, 180°C tensile storage modulus, and 20°C tensile modulus were measured for five samples of wires having the same structure as the papermaking wire 1 of the above embodiment or their bottom wefts. The configurations of the bottom wefts of Comparative Examples 1 and 2 do not correspond to the configuration of the bottom weft 5 of the above embodiment, while the configurations of the bottom wefts of Examples 1 to 3 correspond to the configuration of the bottom weft 5 of the above embodiment. In all samples, the bottom warp was a polyester monofilament single yarn, the top warp was a polyester monofilament single yarn, and the top weft was a nylon and polyester monofilament single yarn. The composition of the bottom wefts used in the tests is shown in Table 1.

[0043] The crystallinity was measured using a differential scanning calorimeter (DSC) and calculated according to the following formula. Crystallinity (%) = Heat of fusion of polyethylene terephthalate (J / g) ÷ Heat of crystallization for complete melting (J / g) The heat of fusion of polyethylene terephthalate was calculated by measuring the heat of fusion near the melting point (250°C) of polyethylene terephthalate and taking into account the blend ratio. The heat of fusion of completely crystalline polyethylene terephthalate was calculated using a literature value of 140 J / g. The test conditions were as follows: Equipment: Shimadzu DSC60-Plus Heating rate: 20℃ / min, under nitrogen atmosphere

[0044] The test equipment used in the wear test was the same as Einlehner AT 2000. The test conditions were as follows: Suspension: 2.2% calcium carbonate (CaCO3) aqueous solution Friction element: ceramic Winding angle: 180° Total test distance: 94.3km · Weight: 1kg ·Water temperature: constant 30℃

[0045] The wire thickness was measured before and after the test, and the abrasion rate was determined as the lower weft abrasion rate, which was the ratio (%) of the wire thickness before the test minus the wire thickness after the test divided by the diameter of the lower weft.

[0046] Measurement of the 180°C tensile storage modulus was carried out using a DVA-225 manufactured by IT Measurement & Control Co., Ltd. The yarn sample was cut into 1 cm pieces, and after measuring the cross-sectional area, it was placed in a device equipped with a tensioning jig and pre-tensioned to prevent slack before measurement. The tensile storage modulus value at 180°C was extracted when measurements were taken from 20°C to 250°C. The test conditions were as follows: ·Test length: 1cm Deformation mode: tension Distortion: 0.05% Heating rate: 10℃ / min Frequency: 10Hz

[0047] Measurement of the tensile modulus at 20°C was carried out using a Toyo Seiki Seisakusho universal testing machine, Strograph E3-L. The slope of the initial linear portion of the tensile test results was taken as the modulus of elasticity. The test conditions were as follows: ·Trial length: 20cm ·Speed: 300m / min Load: 100N

[0048] Tables 1 and 2 show the configuration of the bottom weft and the test results. Pelprene (registered trademark) E-450B was used as the polyester elastomer. Carbodilite (registered trademark) HMV-5CA-LC or HMV15-CA was used as the carbodiimide. [Table 1] [Table 2]

[0049] The abrasion resistance of Examples 1 to 3 was better than that of Comparative Examples 1 and 2. Furthermore, the drainage properties of Examples 1 to 3 were also better than that of Comparative Example 2.

[0050] <Test 2> For wires having the same structure as the papermaking wire 1 of the above embodiment, the abrasion rate and air permeability were measured by changing the ratio of polyethylene terephthalate to polyester elastomer in the bottom weft. Air permeability is an index of the drainage property of the wire. The bottom weft was a monofilament single yarn with a different ratio of polyethylene terephthalate to polyester elastomer. In all samples, the bottom warp was a polyester monofilament single yarn, the top warp was a polyester monofilament single yarn, and the top weft was a nylon and polyester monofilament single yarn.

[0051] The wear test was carried out in the same manner as in the wear test of Test 1, except that the total test distance was 47.1 km, and the wear rate was calculated in the same manner as in Test 1.

[0052] Table 3 shows the elastomer ratio (wt%) used in the test and the measurement results of the wear rate and air permeability. Figure 3 is a graph showing the relationship between the elastomer ratio and the wear rate and air permeability. [Table 3]

[0053] The air permeability of a known wire with the same type of weave as the wire used in the test is 200 mL / m 2 ~250mL / m 2 That's about it.

[0054] When the elastomer ratio is greater than 30%, the air permeability is 190 mL / m 2 It is thought that the elastomer content will be smaller than the original value, and increasing the elastomer content will result in a significant decrease in breathability. For this reason, it is necessary to reduce the thread count of the fabric to increase breathability, but this will deteriorate the surface properties of the wire, and will not meet the surface properties requirements of users. Therefore, it was shown that the elastomer content should be kept below 30%.

[0055] Although the description of specific embodiments has been completed above, the present invention is not limited to the above-described embodiments and modifications, and can be implemented in a wide variety of modifications. Instead of weft-self-binding yarns, warp-self-binding yarns or binding yarns that bind the running surface side layer and the papermaking surface side layer without forming a structure of both layers may be used. As long as the layer closest to the running surface has a structure similar to that of the running surface side layer in the above-described embodiments, the papermaking wire may be composed of one layer, or three or more layers. Papermaking wires may also be used in the wire parts of papermaking machines other than paper machines. [Explanation of symbols]

[0056] 1: Papermaking wire (papermaking fabric) 2: Running surface side layer 3: Papermaking surface layer 4: Lower warp (warp) 5: Lower weft (weft) 6: Upper warp 7: Upper weft 8: Weft self-binding yarn

Claims

1. A papermaking fabric comprising one or more layers including a running surface side layer arranged closest to the running surface, the running side layer includes warp yarns and weft yarns woven together, the weft yarn of the running surface side layer contains polyester yarn whose main component is polyethylene terephthalate, The crystallinity of the polyethylene terephthalate is 22% to 32% based on the total amount of the polyethylene terephthalate; The polyester yarn has a storage modulus at 180°C of 0.19 GPa to 0.28 GPa.

2. 2. The papermaking fabric according to claim 1, wherein the polyester yarn has a tensile modulus at 20°C of 4.8 GPa to 5.3 GPa.

3. 2. The papermaking fabric according to claim 1, wherein the polyester yarns of the weft yarns of the running side layer further contain a polyester elastomer in an amount of 20% by weight to 32% by weight.

4. 4. The papermaking fabric according to claim 3, wherein the polyester yarns of the weft yarns of the running side layer further contain 1% to 4% by weight of carbodiimide.

5. 5. The papermaking fabric according to claim 1, wherein the polyester yarns of the weft yarns of the running surface side layer have a tensile storage modulus at 180°C that is smaller than the tensile storage modulus at 180°C of the warp yarns of the running surface side layer.

6. A method for producing a papermaking fabric in which warp yarns and weft yarns are woven together and the fabric has one or more layers including a running surface side layer disposed closest to the running surface, weaving the one or more layers using polyester yarns, the main component of which is polyethylene terephthalate and has a crystallinity of 22% to 32%, as the weft yarns of the running surface side layer; and applying tension to the woven layer or layers while heating the woven layer or layers at a temperature at which the tensile storage modulus of the polyester yarn is 0.19 to 0.28 GPa.

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