Mesh for sieving net

Abstract

Only reducing mesh opening of a mesh may make it difficult to sieve particles having smaller particle diameters. This mesh for a sieving net is composed of a woven fabric of n / m twilled dutch weave. Each of n and m is a positive integer of 3 or less. The average pore diameter measured by using the bubble point method (ASTM F316-86, JIS K3832) is 1.0-6.5 μm.

Description

Sieve mesh

[0001] The present invention relates to a mesh for a sieve used for sieving, and more particularly to a mesh for a sieve used for a micro sieve of about several μm.

[0002] Powder particles are widely used in various industries, but particles are usually not uniform in size or shape, and it is industrially important to classify particles with a wide particle size distribution to make the particle size uniform. For particles with particle sizes of several tens of μm or more, a method has been adopted in which particles with a particle size above a predetermined value and foreign matter are removed using a plain weave mesh with a mesh number of approximately 100 to 400.

[0003] The smaller the particle size, the smaller the mesh openings used (Patent Document 1).

[0004] Japanese Patent Application Laid-Open No. 2005-246212

[0005] Simply reducing the mesh size may make it difficult to sieve particles with smaller particle sizes.

[0006] An object of the present invention is to provide a mesh for a sieve screen for sieving particles having smaller particle sizes.

[0007] The gist of the present invention is as follows. [1] A mesh for a sieve screen, comprising an n / m twill wavy fabric, wherein n and m are each a positive integer of 3 or less, and wherein the average pore size measured by the bubble point method (ASTM F316-86, JIS K 3832) is 1.0 μm or more and 6.5 μm or less. [2] The mesh for a sieve screen according to [1], wherein the material of the threads constituting the fabric is nylon. [3] The mesh for a sieve screen according to [1], wherein the threads constituting the fabric have a diameter of 10 μm or more and 40 μm or less. [4] The mesh for a sieve screen according to [1], wherein the thickness of the fabric is 75 μm or less. [5] The mesh for a sieve screen according to [1], wherein the threads constituting the fabric are monofilaments. [6] The mesh for a sieve screen according to [1], wherein the mesh number of the fabric is 600 or more and 950 or less.

[0008] According to the present invention, in a twill woven fabric of n / m (n and m are each independent positive integers of 3 or less), by setting the average pore size to 1.0 μm or more and 6.5 μm or less, it is possible to sieve out particles with a smaller particle size (particle size of 1.0 μm or more and 6.5 μm or less).

[0009] 1 is a plan view of a mesh for a sieve screen according to an embodiment of the present invention; FIG. 2 is a diagram illustrating the bending angle of a thread; FIG. 3 is a diagram illustrating the angle of oblique movement of the mesh for a sieve screen; and FIG. 4 is a diagram illustrating a monofilament (a) and a multifilament (b).

[0010] A sieve mesh according to an embodiment of the present invention will be described below with reference to Fig. 1. Fig. 1 is a plan view of the sieve mesh.

[0011] The sieve mesh is made of an n / m twill weave fabric, where n and m are positive integers of 3 or less. Preferably, n and m are the same value. The sieve mesh has an average pore diameter (hereinafter simply referred to as "average pore diameter") measured by the bubble point method (ASTM F316-86, JIS K 3832) of 1.0 μm or more and 6.5 μm or less. The average pore diameter can be measured using a Perm-Porometer (manufactured by Porous Materials, Inc.).

[0012] Twill tatami weave is a weaving method that combines tatami weave and twill weave. Specifically, it is a weaving method in which adjacent warp threads 1 are closely intertwined with weft threads 2 and woven together, and the warp threads 1 pass over a predetermined number of weft threads 2, and then pass under a predetermined number of weft threads 2, repeatedly.

[0013] Tatami weave is a structure in which multiple warp threads 1 are woven closely together and intertwined with weft threads 2, which are arranged at regular intervals. In tatami weave, the multiple warp threads 1 are closely spaced from one another, so openings cannot be seen in a plan view of the mesh. However, when observed from the cross-sectional direction of the mesh, gaps exist at the portions where the warp threads 1 and weft threads 2 intersect three-dimensionally (intersections), and particles can pass through these gaps. Tatami weaves include plain tatami weave, twill tatami weave, and reverse twill tatami weave, and although these tatami weaves differ in the way the warp threads 1 intersect with the weft threads 2, gaps are formed at the intersections of the warp threads 1 and weft threads 2 in all tatami weaves.

[0014] An n / m twill weave is a weave in which warp threads 1 pass over n weft threads 2 and then pass under m weft threads 2, or a weave in which weft threads 2 pass over n warp threads 1 and then pass under m warp threads 1, repeatedly. Twill weave is characterized by the fact that the portions where warp threads 1 pass over weft threads 2 (or weft threads 2 pass over warp threads 1) are offset by a predetermined distance in the warp direction (or the weft direction between adjacent weft threads) between adjacent warp threads 2, forming a linear (strip-like) pattern called a twill that is inclined relative to the warp threads 1 and weft threads 2. A twill weave with n=1 and m=1 is called a plain weave.

[0015] The loom for producing the sieve mesh (woven fabric) is not particularly limited, and for example, a shuttle loom, a gripper loom, a rapier loom, a water jet loom, or an air jet loom can be used. The woven fabric produced by the loom can be used as the sieve mesh, or the sieve mesh can be produced by subjecting the woven fabric produced by the loom to a heat setting treatment.

[0016] The diameters of the warp threads 1 and weft threads 2 used in the sieve mesh are not particularly limited, but are preferably 40 μm or less. Here, the cross-sectional shape of each thread (warp threads 1 and weft threads 2) before weaving the sieve mesh (woven fabric) using the above-mentioned loom is circular, so the diameter of each thread can be 40 μm or less. If the thread diameter exceeds 40 μm, the mesh thickness also increases. As a result, the gaps at the intersections increase, making it difficult to achieve an average pore size of 1.0 μm or more and 6.5 μm or less.

[0017] The bending angle mentioned above is the angle at which each thread (warp thread 1 and weft thread 2) bends at the intersection where the warp thread 1 and the weft thread 2 intersect, and will be specifically explained using FIG. 2 . The angle θ shown in FIG. 2 is the bending angle of the warp thread 1 at the intersection where the warp thread 1 and the weft thread 2a intersect. In FIG. 2 , one warp thread 1 extends in the left-right direction of FIG. 2 , and three weft threads 2a, 2b, and 2c are arranged in the left-right direction of FIG. 2 at a predetermined interval. The weft threads 2a, 2b, and 2c extend in a direction perpendicular to the plane of FIG. 2 . The bending angle θ is the angle (acute angle) formed by a line L1 connecting two reference points P1 and P2 and a line L2 connecting two reference points P1 and P3. Each of the reference points P1 to P3 is located at the radial center of the warp thread 1, with reference point P1 being at a position corresponding to the cross-sectional center of the weft thread 2a, reference point P2 being at a position corresponding to the cross-sectional center of the weft thread 2b, and reference point P3 being at a position corresponding to the cross-sectional center of the weft thread 2c.

[0018] In order to be used as a sieve mesh, a certain tension is applied to the sieve mesh, so the sieve mesh must have the strength to withstand this tension. In consideration of this, it is preferable that the thread diameter of each thread (warp thread 1 and weft thread 2) is 10 μm or more. Furthermore, if the thread diameter is less than 10 μm, it becomes difficult to weave the sieve mesh.

[0019] The thickness of the sieve mesh (woven fabric) is preferably 75 μm or less. If the thickness of the sieve mesh is thicker than 75 μm, the average pore size tends to increase, making it difficult to achieve an average pore size of 1.0 μm or more and 6.5 μm or less. On the other hand, if the thickness of the sieve mesh is too thin, the average pore size may become too small and the mesh may no longer function as a sieve. The thickness of the sieve mesh (woven fabric) depends on the diameter of each thread (warp thread 1 and weft thread 2), the bending angle θ described above, and the degree of oblique correction (angle δ) described below.

[0020] To reduce the thickness of the sieve mesh, the woven fabric manufactured by the above-mentioned loom can be heated and pressed at the same time using a calendering process or the like, thereby reducing the thickness of the sieve mesh and the average pore size. Alternatively, the thickness of the woven fabric may be reduced by heating it while stretching or shrinking it in the direction in which the warp yarns 1 or the weft yarns 2 extend. This also has the effect of reducing the variation in the average pore size.

[0021] The mesh count [counts per inch] of the sieve mesh (woven fabric) is not particularly limited, and can be determined appropriately depending on the average pore size. The mesh count refers to the number of threads per inch (2.54 cm) of the mesh fabric. The mesh count includes the number of meshes in the direction in which the warp threads 1 extend and the number of meshes in the direction in which the weft threads 2 extend. The smaller the mesh count, i.e., the fewer threads per inch, the wider the spacing between adjacent threads in the case of the warp threads 1, making it more difficult to weave a tatami weave. Furthermore, to bring adjacent threads closer together, the thread diameter must be increased, making it more difficult for the warp threads 1 to bend. In either case, the average pore size tends to increase. Furthermore, in the case of the weft threads 2, the spacing (distance) between two adjacent weft threads 2 becomes longer, which tends to increase the average pore size. In order to set the average pore size of the sieve mesh to 1.0 μm or more and 6.5 μm or less, it is preferable that the mesh number be 600 or more. Furthermore, as the mesh number increases, the average pore size becomes smaller, but weaving using the above-mentioned loom becomes difficult, so the mesh number is preferably 950 or less.

[0022] The threads (warp threads 1 and weft threads 2) constituting the sieve mesh (woven fabric) are preferably monofilaments. As shown in Figure 4, the thread width Wa when two monofilaments (a) are used tends to be more uniform than the thread widths Wb1 and Wb2 when a multifilament (b) made up of two monofilaments is used, and this reduces the variation in the average pore size formed in the sieve mesh.

[0023] The material of each thread (warp thread 1 and weft thread 2) is not particularly limited, but it is preferable to use flexible synthetic fibers. Examples of synthetic fiber materials that can be used include polyethylene terephthalate (PET), polypropylene, polyamides such as 6-nylon and 66-nylon, polyethylene (PE), ethylene-vinyl acetate copolymer, polycarbonate, polyphenylene sulfide (PPS), polyethylene naphthalate, polyether ether ketone (PEEK), modified polyphenylene ether (PPE), polyaryl ether ketone (PAEK), polystyrene (PS) including crystalline polystyrene such as syndiotactic polystyrene (SPS) and isotactic polystyrene, and polyimide (PI). In addition, examples of synthetic fiber materials include aramid, polyarylate, ultra-high molecular weight polyethylene, polyparaphenylene benzobisoxazole (PBO), polyparaphenylene benzobisthiazole (PBT), polyparaphenylene benzobisimidazole (PBI), polyacetal resin, polyarylate resin, polysulfone resin, polyvinylidene fluoride resin, thermoplastic resins such as ethylene tetrafluoroethylene (ETFE) and polytetrafluoroethylene (PTFE), polylactic acid resin, polyhydroxybutyrate resin, modified starch resin, polycaprolactone resin, polybutylene Examples of suitable materials include biodegradable resins such as poly(ethylene succinate), poly(butylene adipate terephthalate), poly(butylene succinate terephthalate), and polyethylene succinate; thermosetting resins such as phenolic resin, urea resin, melamine resin, unsaturated polyester resin, diallyl phthalate resin, epoxy resin, epoxy acrylate resin, silicon resin, acrylic urethane resin, and urethane resin; and elastomers such as silicone resin, polystyrene elastomer, polyethylene elastomer, polypropylene elastomer, and polyurethane elastomer. Furthermore, fibers made from fluorine-based fibers, carbon fibers, liquid crystal polymer (LCP) fibers, and natural resins such as lacquer can also be used. Considering the flexibility of the yarn, which facilitates a small bending angle, the strength of the yarn, and the ease of weaving using the loom described above, nylon is particularly preferred as the material for each yarn (warp yarn 1 and weft yarn 2).

[0024] As described above, the sieve mesh (woven fabric) is a twill weave fabric with a ratio of n / m, where n and m are integers of 3 or less. If n and m are greater than 3, the number of times the warp thread 1 passes from above to below the weft thread 2 (or from below to above the weft thread 2) decreases, resulting in a smaller total number of gaps generated at the intersections of the warp thread 1 and the weft thread 2. If the total number of gaps decreases, fewer gaps will pass through the sieve mesh when used as a sieve mesh, resulting in a lower sieving efficiency. Therefore, n and m are each an integer of 3 or less. On the other hand, if n and m are too small, the angle between the warp thread 1 and the weft thread 2 in the plane of the sieve mesh will likely deviate from 90°, resulting in a so-called skew. Since skew increases the average pore size, it is preferable to prevent skew.

[0025] The angle δ shown in Figure 3 is the angle (acute angle) formed by a line extending in the direction of the warp yarns 1 and a line extending in the direction of the weft yarns 2 within the plane of the sieve mesh. The angle (acute angle) δ formed by the line extending in the direction of the warp yarns 1 and the line extending in the direction of the weft yarns 2 can be measured by observation with a microscope. The angle δ is preferably within the range of 90±7° (i.e., 83 to 97°), more preferably within the range of 90±3.5°, and even more preferably within the range of 90±1°.

[0026] If skew occurs, it can be corrected using a skew correction device or the like. The mesh in the skew-corrected state can be maintained by further heating. By correcting the skew, it is possible to reduce the average pore diameter. This allows the average pore diameter to be within the range of 1.0 μm or more and 6.5 μm or less.

[0027] As described above, the average pore diameter formed in the sieve mesh is 1.0 μm or more and 6.5 μm or less. If the average pore diameter is less than 1.0 μm, weaving is difficult and pressure loss during sieving increases. If the average pore diameter exceeds 6.5 μm, adjusting the opening of the sieve mesh makes it easier to improve classification performance and sieving efficiency. In the present invention, by focusing on the average pore diameter measured by the bubble point method, particles with a particle diameter of 1.0 μm or more and 6.5 μm or less can be suitably sieved.

[0028] In the sieve mesh of this embodiment, as described above, there are suitable ranges for n / m, thickness, number of meshes, thread (material, thread diameter, filament configuration), and angle δ, but the present invention includes any combination of these.

[0029] (Example 1) A 3 / 3 twill woven sieve mesh was woven using nylon monofilaments, with warp yarns 1 having a diameter of 35 μm and weft yarns 2 having a diameter of 30 μm, and the number of meshes in the direction in which warp yarns 1 extend (hereinafter referred to as warp mesh number) being 680 and the number of meshes in the direction in which weft yarns 2 extend (hereinafter referred to as weft mesh number) being 640. The sieve mesh had a thickness of 64.0 μm and an angle δ of 89.6°. This angle δ (89.6°) was the average value of the three angles δ measured at three intersections, and all three angles δ were within the range of 90±7°.

[0030] The average pore diameter was measured at five measurement points in the width direction of the sieve mesh (the width of the sieve mesh was approximately 100 cm, and the measurement points were spaced 20 cm apart), and the average value of the average pore diameters at the five measurement points was calculated.

[0031] The average pore diameter was measured by a pore size distribution measurement method (ASTM F316-86, JIS K 3832) using a perm porometer tester (Capillary Flow Porometer CFP1100-AX; manufactured by Porous Materials, Inc.). The sieve mesh was immersed in a fluorine-based inert liquid (3M Fluorinert FC-40, 3M Japan, surface tension 15.9 dyn / cm) as the test liquid, and attached to a 20 mm diameter adapter for measurement. The adapter determines the sample area when measuring the average pore diameter; in this example, a sample area of ​​20 mm diameter was used. The measurement results are shown in Table 1 below.

[0032] (Example 2) A sieve mesh was woven by the same method as in Example 1, except that the number of warp meshes was changed to 670 and the number of weft meshes was changed to 670. This sieve mesh had a thickness of 72.0 μm and an angle δ of 93.3°. This angle δ (93.3°) is the average value of the angles δ (three) measured at three intersections, and all three angles δ were within the range of 90±7°. The method for measuring the average pore diameter was the same as in Example 1. The measurement results of the average pore diameter in Example 2 (the average value of the average pore diameters at five measurement points) are shown in Table 1 below.

[0033] (Example 3) A sieve mesh was woven by the same method as in Example 1, except that the number of warp meshes was changed to 683 and the number of weft meshes was changed to 659. This sieve mesh had a thickness of 52.0 μm and an angle δ of 93.8°. This angle δ (93.8°) is the average value of the angles δ (three) measured at three intersections, and all three angles δ were within the range of 90±7°. The method for measuring the average pore diameter was the same as in Example 1. The measurement results of the average pore diameter in Example 3 (the average value of the average pore diameters at five measurement points) are shown in Table 1 below.

[0034] (Example 4) A sieve mesh was woven by the same method as in Example 1, except that the number of warp meshes was changed to 701, the weft 2 was made of a nylon monofilament having a thread diameter of 25 μm, and the number of weft meshes was changed to 904. The sieve mesh had a thickness of 65.0 μm and an angle δ of 89.6°. This angle δ (89.6°) is the average value of the angles δ (three) measured at three intersections, and all three angles δ were within the range of 90±7°. The method for measuring the average pore diameter was the same as in Example 1. The measurement results of the average pore diameter in Example 4 (the average value of the average pore diameters at five measurement points) are shown in Table 1 below.

[0035] (Example 5) The mesh woven in Example 4 was subjected to calendering to make the thickness of the sieve mesh 52.0 μm. After calendering, the number of warp meshes was 712, the number of weft meshes was 912, and the angle δ was 86.9°. This angle δ (86.9°) is the average value of the angles δ (three) measured at three intersections, and all three angles δ were within the range of 90±7°. The method for measuring the average pore diameter was the same as in Example 1. The measurement results of the average pore diameter in Example 5 (the average value of the average pore diameters at five measurement points) are shown in Table 1 below.

[0036] (Example 6) A sieve mesh was woven by the same method as in Example 1, except that the number of warp meshes was changed to 660 and the number of weft meshes was changed to 670. This sieve mesh had a thickness of 70.1 μm and an angle δ of 94.4°. This angle δ (94.4°) is the average value of the angles δ (three) measured at three intersections, and all three angles δ were within the range of 90±7°. The method for measuring the average pore diameter was the same as in Example 1. The measurement results of the average pore diameter in Example 6 (the average value of the average pore diameters at five measurement points) are shown in Table 1 below.

[0037] (Comparative Example 1) A sieve mesh having a 2 / 2 twill weave was woven using nylon monofilaments as warp yarns 1 and weft yarns 2, each having a diameter of 30 μm, with a warp mesh count of 560 and a weft mesh count of 530. The sieve mesh had a thickness of 47.2 μm and an angle δ of 90.1°. This angle δ (90.1°) was the average value of the three angles δ measured at three intersections, and all three angles δ were within the range of 90±7°. The average pore diameter was measured using the same method as in Example 1. The measurement results of the average pore diameter in Comparative Example 1 (the average value of the average pore diameters at five measurement points) are shown in Table 1 below.

[0038] (Comparative Example 2) A sieve mesh having a 4 / 4 twill weave was woven using nylon monofilaments as warp yarns 1 and weft yarns 2, each having a diameter of 37 μm, with a warp mesh count of 680 and a weft mesh count of 470. The sieve mesh had a thickness of 84.4 μm and an angle δ of 90.3°. This angle δ (90.3°) was the average value of the three angles δ measured at three intersections, and all three angles δ were within the range of 90±7°. The average pore diameter was measured using the same method as in Example 1. The measurement results of the average pore diameter in Comparative Example 2 (the average value of the average pore diameters at five measurement points) are shown in Table 1 below.

[0039]

[0040] In Examples 1 to 6, sieve meshes having an average pore diameter of 6.5 μm or less were obtained, but in Comparative Examples 1 and 2, the average pore diameter was larger than 6.5 μm. In Comparative Example 1, the number of warp meshes and the number of weft meshes were small, less than 600, and the twill weave was 2 / 2, so the average pore diameter was 9.2 μm (6.5 μm or more). In Comparative Example 2, the number of weft meshes was small, less than 600, and the twill weave was 4 / 4, so the average pore diameter was 7.9 μm (6.5 μm or more).

[0041] 1: warp thread, 2, 2a, 2b, 2c: weft thread, P1 to P3: reference points, L1, L2: straight lines, θ: bending angle

Claims

1. A mesh for a sieve, comprising an n / m twill woven fabric, wherein each of n and m is a positive integer of 3 or less, and the average pore size measured by the bubble point method (ASTM F316-86, JIS K 3832) is 1.0 μm or more and 6.5 μm or less.

2. The sieve mesh according to claim 1, wherein the material of the threads constituting the woven fabric is nylon.

3. A mesh for a sieve screen according to claim 1, characterized in that the diameter of the threads constituting the woven fabric is 10 μm or more and 40 μm or less.

4. The mesh for a sieve screen according to claim 1, characterized in that the thickness of the woven fabric is 75 μm or less.

5. The mesh for a sieve screen according to claim 1, characterized in that the threads constituting the woven fabric are monofilaments.

6. A mesh for a sieve screen according to claim 1, characterized in that the mesh number of the woven fabric is 600 or more and 950 or less.

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