Filter and method of manufacturing the same

Abstract

To provide a filter that comprises a cylindrical pleat filter material which has its opposed end parts suitably bonded together.SOLUTION: It is found that opposed end parts of a filter material having nonwoven fabric layers and cloth layers are tightly bonded together at a part of a cylindrical pleat filter material that is formed of the filter material and has the opposed end parts bonded with an adhesion layer with cloth layers opposed to each other when the adhesion layer is present over the segment connecting both opposite nonwoven fabric layers at the shortest distance and / or when the adhesion layer is present over the segment parallel with the segment and connecting both the opposed nonwoven fabric layers together. Consequently, there is provided the cylindrical pleat filter material that has the opposed end parts bonded tightly with the adhesion layer.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a filter comprising a tubular pleated filter medium in which opposing ends of the filter medium are folded in a zigzag shape and then bonded together to form a hollow cylinder. [Background technology]

[0002] Filters are required to have low pressure loss and are less likely to become clogged due to dust capture. In order to produce filters that satisfy such demands with good productivity, as disclosed in Patent Document 1 (JP 2016-168519 A), for example, a filter is being considered that includes a cylindrical pleated filter material formed into a hollow cylindrical shape by bonding opposing ends of a filter material that has been folded into a zigzag shape between opposing ends.

[0003] The filter having this configuration can be provided with a filter medium having a large area by folding the opposing ends into a zigzag shape, thereby increasing the area available for filtering, thereby realizing a filter with low pressure loss and low clogging caused by dust capture.

[0004] It is disclosed that the cylindrical pleated filter medium disclosed in Patent Document 1 is formed by bonding the ends of the filter medium together with an adhesive layer derived from double-sided tape, etc. However, other than that, no details of the adhesive layer are disclosed, and no detailed consideration has been given to its configuration. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2016-168519 (0034, Fig. 3, etc.) Summary of the Invention [Problem to be solved by the invention]

[0006] In order to realize a filter with even lower pressure loss, the applicant of the present application tried to use a nonwoven fabric as the filter medium and reduce its basis weight. The filter medium thus prepared had a low pressure loss, but the strength was also reduced.

[0007] Therefore, the applicant of the present application attempted to use a laminate made by reinforcing a nonwoven fabric with a woven fabric as a filter medium. The filter medium prepared in this manner showed that the decrease in strength was suppressed.

[0008] However, when the opposing ends of the filter medium (a laminate formed by reinforcing nonwoven fabric with cloth) were folded into a zigzag shape, and then the cloth layers of the filter medium were placed facing each other and the ends were bonded together with an adhesive component to prepare a cylindrical pleated filter medium, it was found that the adhesion between the ends was unintentionally weak, such as interlayer delamination occurring between the cloth layers or between the cloth and the nonwoven fabric.

[0009] Therefore, when an external force is applied to the cylindrical pleated filter medium, delamination occurs between the fabrics or between the fabric and the nonwoven fabric, and the ends are easily separated from each other. As a result, there is a risk that leakage will occur in the filter, and the dust collection performance will decrease.

[0010] An object of the present invention is to provide a filter comprising a tubular pleated filter medium in which opposing ends of the filter medium are suitably bonded to each other. [Means for solving the problem]

[0011] The present invention relates to “(Claim 1) A filter comprising a cylindrical pleated filter medium, the opposing ends of which are folded in a zigzag shape, and the opposing ends are bonded together to form a hollow cylindrical shape, The filter medium comprises a nonwoven fabric layer and a fabric layer, The fabric layers are faced to each other, and the facing ends are bonded to each other by an adhesive layer, In a portion where the opposing ends are bonded to each other by an adhesive layer, the adhesive layer is present on a line segment that connects the nonwoven fabric layer of one of the opposing ends to the nonwoven fabric layer of the other of the opposing ends at the shortest distance, and / or on another line segment that is parallel to the line segment and connects the nonwoven fabric layer of one of the opposing ends to the nonwoven fabric layer of the other of the opposing ends. filter. (Claim 2) (Step 1) preparing a filter medium having a nonwoven fabric layer and a fabric layer; (Step 2) folding the opposing ends of the filter material into a zigzag shape; (Step 3) A step of overlapping the opposing ends of the filter material folded into the zigzag shape by providing a layer of an adhesive component capable of forming an adhesive layer between the fabric layers in a state in which the fabric layers face each other, (Step 4) applying pressure or heat and pressure to the overlapped portion of the ends; The method for manufacturing a filter includes a cylindrical pleated filter material formed into a hollow cylindrical shape by bonding the opposing ends of the filter material folded into a zigzag shape, The method for producing a filter, wherein in the step 3, the thickness of the adhesive layer is at least twice the thickness of the fabric layer. (Claim 3) The method for producing a filter according to claim 2, wherein the layer of adhesive component is a double-sided tape. It is. Effect of the Invention

[0012] As a result of the applicant's continued investigations, it was found that in a filter comprising a cylindrical pleated filter medium in which opposing ends of a filter medium are folded into a zigzag shape and the opposing ends are bonded together to form a hollow cylinder, the filter medium comprising a nonwoven fabric layer and a fabric layer, the opposing ends being bonded together by an adhesive layer with the fabric layers facing each other, When the adhesive layer is present on a line segment connecting a nonwoven fabric layer at one of the opposing ends and a nonwoven fabric layer at the other opposing end at the shortest distance, and / or When the adhesive layer is present on another line segment (hereinafter sometimes abbreviated as another line segment) that is parallel to the line segment and connects the nonwoven fabric layer of one of the opposing ends and the nonwoven fabric layer of the other of the opposing ends, It was found that the opposing ends of the filter media were firmly bonded to each other.

[0013] The reason why this effect is exerted has not been fully clarified, but it is thought to be due to the following effects.

[0014] In the portion where the opposing ends are bonded by the adhesive layer, the presence of the adhesive layer on the line segment connecting the nonwoven fabric layers at the shortest distance and / or on another line segment means that the adhesive layer is present from the nonwoven fabric layer side principal surface of one fabric layer to the nonwoven fabric layer side principal surface of the other fabric layer at the opposing ends. Therefore, the adhesive layer is present throughout the thickness direction of the fabric layers in the portion, so that the fabric layers are bonded reliably and firmly.

[0015] In addition, in this portion, not only are the fabric layers bonded to each other by the adhesive layer, but the fabric layers and nonwoven fabric layers, and the nonwoven fabric layers are also bonded to each other.

[0016] Therefore, in the cylindrical pleated filter medium according to the present invention, the opposing ends are firmly bonded to each other by the adhesive layer.

[0017] Furthermore, the manufacturing method for a filter including a cylindrical pleated filter material according to the present invention is characterized in that in the process of providing a layer of an adhesive component capable of forming an adhesive layer between fabric layers and overlapping the ends of the fabric layers, the thickness of the layer of adhesive component capable of forming an adhesive layer is at least twice the thickness of the fabric layers.

[0018] By carrying out this step, in the portion where the opposing ends are bonded together by the adhesive layer, the adhesive layer can be present on the line segment that connects the nonwoven fabric layer of one of the opposing ends with the nonwoven fabric layer of the other of the opposing ends at the shortest distance and / or on another line segment. As a result, a filter having a cylindrical pleated filter medium having the configuration according to the present invention can be manufactured.

[0019] Furthermore, when the adhesive layer is a double-sided tape, that is, when a filter having a cylindrical pleated filter medium is manufactured by overlapping the ends using a double-sided tape having a thickness of at least two layers of the fabric layer, it was found that the opposing ends of the manufactured cylindrical pleated filter medium are firmly bonded to each other, and the elongation of the part where the ends are bonded to each other is improved. Therefore, even when an external force is applied to the cylindrical pleated filter medium, the part is easily stretched and can follow the external force, so that a filter having a cylindrical pleated filter medium in which the ends are not easily separated from each other can be manufactured.

[0020] As described above, the present invention can provide a filter including a cylindrical pleated filter medium in which opposing ends of the filter medium are more suitably bonded to each other. [Brief description of the drawings]

[0021] [Figure 1] FIG. 1A is a schematic front view of a filter material whose opposing ends are folded into a zigzag shape, as viewed from the fabric layer side; FIG. 1B is a schematic side view of a filter material whose opposing ends are folded into a zigzag shape, as viewed from the side. [Diagram 2] FIG. 2 is a schematic perspective view of a cylindrical pleated filter medium. [Diagram 3] 1 is a schematic enlarged view showing a portion of a cylindrical pleated filter medium where opposing ends are bonded to each other by an adhesive layer. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0022] In the present invention, various configurations, such as the following configurations, can be appropriately selected. Note that, unless otherwise specified, the various measurements described in the present invention are performed under atmospheric pressure. In addition, measurements are performed under a temperature condition of 25°C. And, unless otherwise specified, the various measurement results described in the present invention are measured to a value one digit smaller than the desired value, and the value is calculated by rounding off the value. As a specific example, when the desired value is to the first decimal place, the value is measured to the second decimal place, and the obtained value to the first decimal place is rounded off to calculate the value to the first decimal place, and this value is the desired value. And, each upper limit value and each lower limit value exemplified in the present invention can be arbitrarily combined.

[0023] The filter medium according to the present invention includes a nonwoven fabric layer and a cloth layer. As a specific example, a filter medium including a laminate in which a nonwoven fabric layer and a cloth layer are laminated, or a filter medium consisting of only the laminate can be used.

[0024] The nonwoven fabric layer here refers to a layer of fibers formed by entanglement of fibers, and can be, for example, a fiber layer derived from a dry nonwoven fabric or a fiber layer derived from a wet nonwoven fabric. In a filter medium, the nonwoven fabric layer is a layer that mainly plays a role of collecting the object to be filtered that passes through the filter, and contributes to providing a filter that has a lower initial pressure loss, is excellent in collection properties, and is easy to maintain filtration performance for a long period of time.

[0025] The fabric layer is a layer derived from a fabric having a plurality of voids, and can be, for example, a fiber layer formed by weaving together fibers (such as a fiber layer derived from a woven fabric), or a fiber layer formed by knitting together fibers (such as a fiber layer derived from a knitted fabric). The fabric layer may be a fiber layer derived from another nonwoven fabric, which has a higher rigidity than the nonwoven fabric layer described above. In the filter material, the fabric layer is a layer that mainly plays a role in reinforcing the nonwoven fabric layer described above, and it is preferable that the fabric layer is a fiber layer derived from a knitted fabric so that the nonwoven fabric layer can be efficiently reinforced.

[0026] The fabric layer has voids extending from one main surface to the other main surface, and the adhesive layer is held in the voids.

[0027] The fibers constituting the nonwoven fabric layer or the cloth layer may be inorganic fibers such as glass fibers, metal oxide fibers such as silica fibers or alumina fibers, or organic fibers such as polypropylene fibers. The organic fibers may be, for example, polyolefin resins (e.g., polyethylene, polypropylene, polymethylpentene, polyolefin resins having a structure in which a part of a hydrocarbon is substituted with a cyano group or a halogen such as fluorine or chlorine), styrene resins, polyvinyl alcohol resins, polyether resins (e.g., polyether ether ketone, polyacetal, modified polyphenylene ether, aromatic polyether ketone, etc.), polyester resins (e.g., polyethylene terephthalate, polytrimethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, polycarbonate, polyarylate, wholly aromatic polyester resins, etc.), polyimide resins, etc. It can be constructed using known resins such as polyamideimide resin, polyamide-based resin (e.g., aromatic polyamide resin, aromatic polyetheramide resin, nylon resin, etc.), resin having a nitrile group (e.g., polyacrylonitrile, etc.), urethane-based resin, epoxy-based resin, polysulfone-based resin (e.g., polysulfone, polyethersulfone, etc.), fluorine-based resin (e.g., polytetrafluoroethylene, polyvinylidene fluoride, etc.), cellulose-based resin, polybenzimidazole resin, acrylic resin (e.g., polyacrylonitrile-based resin copolymerized with acrylic acid ester or methacrylic acid ester, modacrylic resin copolymerized with acrylonitrile and vinyl chloride or vinylidene chloride, etc.).

[0028] The resin may be a linear polymer or a branched polymer, may be a block copolymer or a random copolymer, may have a three-dimensional structure, may have crystallinity, or may not have crystallinity. Furthermore, the organic fiber may be a fiber made of a mixture of multiple types of the resin.

[0029] The constituent fibers of the nonwoven fabric layer preferably contain glass fibers, and more preferably consist of only glass fibers, in order to provide a filter that has a lower initial pressure loss and excellent collection properties and that is easy to maintain its filtration performance for a long period of time.

[0030] On the other hand, the constituent fibers of the fabric layer preferably contain organic fibers in order to provide excellent adhesion to the nonwoven fabric layer and the adhesive layer described below, and it is more preferable that the constituent fibers are only organic fibers (for example, only polypropylene fibers).

[0031] The constituent fibers of the nonwoven fabric layer can be obtained by known methods such as melt spinning, dry spinning, wet spinning, direct spinning (melt blowing, spunbonding, electrostatic spinning, etc.), a method of extracting fibers having a small fiber diameter by removing one or more types of resin components from composite fibers, and a method of beating fibers to obtain split fibers.

[0032] The fibers constituting the nonwoven fabric layer may be composed of a resin capable of forming one type of inorganic component or organic fiber, or may be composed of resins capable of forming multiple types of inorganic components or organic fibers, such as composite fibers described below. Fibers comprising resins capable of forming multiple types of inorganic components or organic fibers may be in the form of what are generally called composite fibers, such as core-sheath type, sea-island type, side-by-side type, orange type, bimetal type, and the like.

[0033] The fibers constituting the nonwoven fabric layer may include irregular cross-sectional fibers other than those having a substantially circular or elliptical cross-sectional shape. The irregular cross-sectional fibers may have a fiber cross-section having a hollow shape, a polygonal shape such as a triangular shape, an alphabetic shape such as a Y-shape, an irregular shape, a multi-lobed shape, a symbolic shape such as an asterisk shape, or a shape in which a plurality of these shapes are combined.

[0034] When the nonwoven fabric layer or the cloth layer contains a heat-fusible composite fiber as a constituent fiber, the constituent fibers are heat-fusible to impart strength and shape stability to the filter medium, which is preferable. As such a heat-fusible composite fiber, a partially fused composite fiber can be used.

[0035] Nonwoven fabrics that can form the nonwoven fabric layer can be prepared, for example, by a dry method in which the above-mentioned fibers are fed into a carding device or an air-laying device to entangle the fibers; a wet method in which the fibers are dispersed in a dispersion medium and laid into a sheet to entangle the fibers; or a method in which the fibers are spun using a direct spinning method (such as a melt-blowing method, a spunbonding method, an electrostatic spinning method, or a method in which a spinning solution and a gas flow are discharged in parallel to spin the fibers (for example, the method disclosed in JP 2009-287138 A)) and the spun fibers are entangled and collected.

[0036] In addition, a nonwoven fabric layer derived from a nonwoven fabric formed from a mixture of fibers having a continuous length and fibers having a specific fiber length is preferable because it can provide a filter that has a lower initial pressure loss and excellent collection properties, and that is also likely to maintain its filtration performance for a long period of time.

[0037] In addition, the constituent fibers of the nonwoven fabric capable of forming the nonwoven fabric layer may be further integrated. In addition to integrating the constituent fibers by bonding them together with an adhesive component described below, examples of the method for integrating the constituent fibers include a method of entangling them with a needle or a water flow, and a method of fusing the constituent fibers together with fully fused fibers or partially fused composite fibers contained in the constituent fibers by subjecting them to a heat treatment or the like.

[0038] The heat treatment method can be appropriately selected, and examples of the method that can be used include heating or heating and pressurizing with a roll, heating by subjecting the material to a heater such as an oven dryer, a far-infrared heater, a dry heat dryer, or a hot air dryer, and heating the adhesive component contained therein by irradiating the material with infrared rays without pressure.

[0039] The average fiber diameter and fiber length of the fibers constituting the nonwoven fabric layer are not particularly limited, but can be appropriately adjusted to provide a filter that has a lower initial pressure loss, excellent collection properties, and is easy to maintain filtration performance for a long period of time. The average fiber diameter can be 0.1 to 50 μm, 0.2 to 30 μm, or 0.3 to 10 μm. The constituent fibers can be fibers having a continuous length without a specific length, such as directly spun fibers (melt-blown fibers and electrospun fibers). Alternatively, the constituent fibers can be fibers cut to have a specific fiber length, and the fiber length can be 10 to 120 mm, 20 to 100 mm, or 30 to 80 mm. The "fiber length" refers to a value measured in accordance with JIS L1015 (2010), 8.4.1c) direct method (C method).

[0040] The configurations of the nonwoven fabric layer, such as the thickness and basis weight, are not particularly limited, but can be appropriately adjusted so as to provide a filter that has a lower initial pressure loss, is excellent in collection ability, and is easy to maintain filtration performance for a long period of time. The thickness can be 0.1 to 50 mm, can be 0.2 to 40 mm, or can be 0.3 to 30 mm. The basis weight is 5 to 500 g / m 2 and can be 10 to 400 g / m 2 and can be 30 to 300 g / m 2 In the present invention, the thickness is 0.5 g / cm in the direction perpendicular to the main surface. 2 This refers to the length between the two principal surfaces in the perpendicular direction when a compressive load is applied, and the basis weight is the surface area per square meter of the surface (principal surface) with the widest area of ​​the object being measured. 2 This refers to the mass per unit.

[0041] The diameter and length of the fibers constituting the fabric layer, and the thickness and basis weight of the fabric layer are not particularly limited, but can be appropriately adjusted so as to efficiently reinforce the nonwoven fabric layer. The diameter of the fabric layer can be 0.02 to 7 mm, 0.03 to 5 mm, or 0.05 to 1 mm. By using a woven fabric or knitted fabric (knit) having the above diameter, a filter medium having a fabric layer having the above diameter can be prepared. When the fabric layer is a fiber layer derived from another nonwoven fabric, the average fiber diameter of the fabric layer can be 0.2 to 70 μm, 0.3 to 50 μm, or 0.5 to 10 μm.

[0042] The yarn constituting the fabric layer may be a fiber having a continuous length without a specific length. By using a woven fabric or knitted fabric including the yarn, a filter medium including a fabric layer including the constituent fiber can be prepared.

[0043] The thickness of the fabric layer may be 0.1 to 50 mm, may be 0.2 to 40 mm, or may be 0.3 to 30 mm. The basis weight of the fabric layer may be 5 to 500 g / m 2 and can be 10 to 400 g / m 2 and can be 30 to 300 g / m 2 It can be.

[0044] The mesh size of the woven or knitted fabric constituting the fabric layer can be 0.3 to 50 mm, 0.5 to 40 mm, or 0.6 to 30 mm. The "mesh size" here refers to the length of one side of a mesh-like opening formed by the constituent fibers. If the shape of the opening is not rectangular, a square having the area of ​​the opening is assumed, and the length of one side of the square is taken as the mesh size of the opening.

[0045] The lamination mode of the nonwoven fabric layer and the cloth layer can be adjusted appropriately. The filter material may be one in which the nonwoven fabric layer and the cloth layer are bonded together by providing a layer of binder or a layer of hot melt web between them. Alternatively, the filter material may be one in which the nonwoven fabric layer and the cloth layer are integrated together by melting or softening the thermoplastic resin fiber contained in the nonwoven fabric layer and / or the cloth layer and bonding them together. In particular, it is preferable that the filter material is one in which the nonwoven fabric layer and the cloth layer are integrated together by melting or softening the thermoplastic resin fiber contained in the cloth layer so that the nonwoven fabric layer and the cloth layer are firmly bonded together.

[0046] The filter material prepared as described above is folded into a zigzag shape, but the filter material prepared by providing a separately prepared cloth (nonwoven fabric, woven fabric, knitted fabric, etc.) or a porous film on the nonwoven fabric layer side can also be folded into a zigzag shape.At this time, the lamination state of the nonwoven fabric layer and the separately prepared cloth or porous film can be appropriately adjusted in the same manner as the lamination state of the nonwoven fabric layer and the cloth layer.

[0047] The thickness and basis weight of the filter material are not particularly limited, but can be appropriately adjusted to provide a filter that has a lower initial pressure loss, is excellent in collection ability, and is easy to maintain its filtering performance for a long period of time. The thickness can be 0.2 to 100 mm, 0.3 to 50 mm, or 0.6 to 30 mm. The basis weight is 10 to 1000 g / m 2 and can be 50-500g / m 2 and can be 80 to 300 g / m 2 It can be.

[0048] The filter material according to the present invention, in which opposing ends are folded into a zigzag shape, will be described with reference to FIG. 1(a), which is a schematic front view of the filter material as viewed from the fabric layer side, and FIG. 1(b), which is a schematic side view of the filter material as viewed from the side.

[0049] The filter medium shown in Fig. 1 is, for example, a laminate of a rectangular nonwoven fabric layer (1) and a fabric layer (2), and the opposing ends (12) having opposing sides (11) are folded in a zigzag shape between them. In other words, mountain folds and valley folds are alternately made between the opposing ends (12) to fold them in a zigzag shape, forming a pleated filter medium (100).

[0050] Here, as shown in Fig. 1(b), when the pleated filter medium (100) is placed on a plate (3) having a flat main surface, the folded portion of the pleated filter medium (100) on the upper side of the paper in the direction perpendicular to the main surface of the plate (the vertical direction on the paper) is called the pleat peak (A), and the folded portion of the pleated filter medium (100) on the lower side of the paper is called the pleat valley (B). Note that the upper end of the pleat peak (A) on the paper and / or the lower end of the pleat valley (B) on the paper may have a curved structure.

[0051] The pleat height (C) is the shortest distance connecting the main surface of the plate (3) and the pleat peak (A) in the direction perpendicular to the main surface of the plate (3) (the vertical direction on the paper). The pleat height (C) of the pleated filter medium (100) is appropriately adjusted so as to provide a filter that has lower initial pressure loss, excellent collection properties, and is easy to maintain filtration performance for a long period of time, and can be 3 to 100 mm, 4 to 50 mm, or 5 to 30 mm.

[0052] In addition, the length (D1) of the shortest distance between adjacent pleat peaks (A) or the length (D2) of the shortest distance between adjacent pleat valleys (B) of the pleated filter medium (100) is appropriately adjusted so as to provide a filter that has lower initial pressure loss and excellent collection properties and is easy to maintain its filtration performance for a long period of time, and can be 1 to 100 mm, 2 to 50 mm, or 3 to 25 mm.

[0053] The cylindrical pleated filter medium (200) according to the present invention will be described with reference to FIG. 2, which is a schematic perspective view of the cylindrical pleated filter medium, and FIG. 3, which is a schematic enlarged view of a portion of the cylindrical pleated filter medium where opposing ends are bonded to each other by an adhesive layer.

[0054] In the cylindrical pleated filter medium (200) of the present invention, the fabric layers (2a, 2b) face each other, and the ends (12) of the filter medium are bonded to each other by an adhesive layer (21). This forms a portion (20) where the opposing ends (12) are bonded to each other by the adhesive layer (21), and the filter medium (100) that has been folded into a zigzag shape has a cylindrical form.

[0055] Here, when the fabric layers (2a, 2b) face each other, the opposing ends (12) are bonded to each other by the adhesive layer (21) means that the fabric layers (2a, 2b) are bonded to each other only via the adhesive layer (21) therebetween.

[0056] The adhesive layer (21) used in the present invention plays a role of bonding the ends (12) of the filter medium together. The adhesive layer (21) is also present in the gaps of the fabric layers (2a, 2b), so that the adhesive layer (21) not only bonds the fabric layers (2a, 2b) together, but also bonds the fabric layers and the nonwoven fabric layers (2a and 1a and 2b and 1b), and also bonds the nonwoven fabric layers (1a and 1b). The adhesive layer (21) is in contact with the nonwoven fabric layers (1a, 1b), and may also penetrate into the gaps of the nonwoven fabric layers (1a, 1b).

[0057] The composition of the adhesive layer (21) can be adjusted as appropriate so long as it can fulfill the above-mentioned role. For example, it can be a layer containing an adhesive component such as a urethane resin, an acrylic resin, or a silicone resin.

[0058] The cylindrical pleated filter material (200) of the present invention is characterized in that, in a portion (20) where opposing ends (12) are adhered to each other by an adhesive layer (21), the adhesive layer (21) is present along a line segment (E) that connects, at the shortest distance, the nonwoven fabric layer (1a) at one of the opposing ends (12) and the nonwoven fabric layer (1b) at the other opposing end (12).

[0059] Whether or not the cylindrical pleated filter medium (200) satisfies the above configuration can be confirmed by the following method. (1) A dye solution (such as Kayastain Q (manufactured by Nippon Kayaku Co., Ltd.)) capable of dyeing the adhesive layer (21) and the fabric layer (2) and / or the nonwoven fabric layer (1) is prepared. (2) Using a dye solution, the adhesive layer (21) and the fabric layer (2) and / or nonwoven fabric layer (1) present in the portion (20) where the ends (12) of the tubular pleated filter medium (200) are bonded together are dyed. (3) The portion (20) where the ends (12) of the filter medium (100) are bonded to each other, which constitutes the cylindrical pleated filter medium (200) after dyeing, is cut in the thickness direction of the filter medium (100), and both main surfaces of the cut portion (20) are sandwiched between glass plates, held, and fixed (pressure applied in the thickness direction by the glass plates: 20 g / cm 2 )do. (4) Next, a micrograph of the cut surface is taken in this state. The photograph is taken so that the entire thickness of the filter medium (100) is included within the vertical range of the micrograph. In other words, the photograph is taken so that the entire laminated configuration of the nonwoven fabric layer-two woven fabric layers and the layer including the adhesive layer-nonwoven fabric layer sandwiched between the glass plates is visible in the micrograph. (5) On the micrograph obtained by photographing, a line segment (E) is drawn that connects, over the shortest distance, the nonwoven fabric layer (1a) at one of the opposing ends (12) to the nonwoven fabric layer (1b) at the other of the opposing ends (12). Next, on the micrograph obtained by photographing, 100 other line segments (a line segment different from line segment (E) (another line segment), not shown) that are parallel to line segment (E) and connect the nonwoven fabric layer (1a) at one of the opposing ends (12) to the nonwoven fabric layer (1b) at the other of the opposing ends (12) are randomly drawn. The drawn line segment passes through one or more voids in the fabric other than the constituent components (constituent fibers, etc.) of the fabric. In addition, when another void exists between the fabric layers (2a, 2b), for example when the fabric layers (2a, 2b) are separated from each other, the drawn line segment passes through one or more of the other voids. (6) In the micrograph in which each line segment (not shown except for line segment (E)) is drawn, first, check whether the adhesive component constituting the adhesive layer (21) is present at all the places where line segment (E) overlaps with the void, or where line segment (E) overlaps with the void and the other void. Next, check the remaining other line segments in the same way. (7) If, as a result of the check in (6) above, the adhesive component that constitutes the adhesive layer (21) is present in all of the locations where the void or the void and the other void overlap in at least one of the line segments (not shown other than line segment (E)), it is determined that, in the portion (20) where the opposing ends (12) are bonded to each other by the adhesive layer (21), the adhesive layer (21) is present along line segment (E) and / or along another line segment (not shown) that connects, at the shortest distance, the nonwoven fabric layer (1a) at one of the opposing ends and the nonwoven fabric layer (1b) at the other of the opposing ends. (8) On the other hand, if, as a result of the check in (6) above, the adhesive component constituting the adhesive layer (21) is not present in any of the lines (not shown except for line (E)) at any of the points where the void or the void overlaps with another void, it is determined that, in the portion (20) where the opposing ends (12) are bonded to each other by the adhesive layer (21), the adhesive layer (21) is not present on line (E) or on another line (not shown) that connects, at the shortest distance, the nonwoven fabric layer (1a) at one of the opposing ends and the nonwoven fabric layer (1b) at the other of the opposing ends.

[0060] In the cylindrical pleated filter medium (200) having the configuration of the present invention described above, the thickness of the adhesive layer (21) on the line (E) drawn on the micrograph and / or on another line (not shown) is at least twice the thickness of the fabric layer (2). Therefore, for example, the length of the line (E) is at least the sum of the length from one end of the line (E) to the main surface of the fabric layer (2a) (Fa, the thickness of one fabric layer) and the length from the other end of the line (E) to the main surface of the fabric layer (2b) (Fb, the thickness of the other fabric layer).

[0061] By providing this configuration, it is possible to provide a filter including a cylindrical pleated filter medium (200) in which opposing ends (12) of the filter medium are appropriately bonded to each other.

[0062] The reason why this effect is exerted has not been fully clarified, but it is thought to be due to the following effects.

[0063] In the portion (20) where the opposing ends (12) are bonded together by the adhesive layer (21), if the adhesive layer (21) exists on the line segment (E) connecting the nonwoven fabric layers (1a, 1b) at the shortest distance and / or on another line segment (not shown), the adhesive layer (21) exists from the nonwoven fabric layer (1a) side main surface of one fabric layer (2a) to the nonwoven fabric layer (1b) side main surface of the other fabric layer (2b) between the opposing ends (12). Therefore, the adhesive layer (21) exists over the entire thickness direction of the fabric layers (2a, 2b) in the portion (20), thereby ensuring a secure and strong bond between the fabric layers (2a, 2b).

[0064] In addition, in this portion (20), not only is the adhesive layer (21) bonding the fabric layers (2a, 2b) together, but the adhesive layer (21) also bonds the fabric layers to the nonwoven fabric layers (2a and 1a, and 2b and 1b), and also bonds the nonwoven fabric layers to each other (1a and 1b).

[0065] Therefore, in the cylindrical pleated filter medium (200) according to the present invention, the opposing ends (12) are firmly bonded to each other by the adhesive layer (21).

[0066] As a result, it is believed that in the cylindrical pleated filter medium (200) of the present invention, the ends (12) are less likely to come apart even when an external force is applied to the cylindrical pleated filter medium (200).

[0067] In particular, when a straight line (not shown) formed by extending the line segment (E) and another line segment is drawn on a micrograph in which the line segment (E) and another line segment are drawn, it is preferable that the adhesive component constituting the adhesive layer (21) is also present in the gaps of the nonwoven fabric layer (1a or 1b, more preferably 1a and 1b) that overlaps with the straight line. In the cylindrical pleated filter medium (200) of this embodiment, the adhesive component constituting the adhesive layer (21) penetrates into the inside of the nonwoven fabric layer (1a and / or 1b). Therefore, the fabric layer and the nonwoven fabric layer (2a and 1a and / or 2b and 1b) and the nonwoven fabric layers (1a and 1b) are more firmly bonded to each other, and therefore it is preferable to provide a cylindrical pleated filter medium (200) in which the opposing ends (12) are firmly bonded to each other by the adhesive layer (21).

[0068] In the cylindrical pleated filter medium (200) of the present invention, when the adhesive layer (21) bonds the fabric layers (2a, 2b) to each other in the entire portion where the fabric layers (2a, 2b) face each other in the portion (20) where the opposing ends (12) are bonded to each other by the adhesive layer, it is preferable because this provides a cylindrical pleated filter medium (200) in which the opposing ends (12) are most firmly bonded to each other by the adhesive layer (21).

[0069] The thickness of the adhesive layer (21) can be appropriately adjusted as long as the configuration of the present invention is satisfied, and can be 0.5 to 5 mm, 0.6 to 4 mm, or 0.7 to 3 mm.

[0070] The shape of the cylindrical pleated filter medium (200) can be adjusted appropriately depending on the intended use and function of the filter.

[0071] The length in the direction parallel to a line formed by continuously connecting the apexes of the pleat peaks (A) in the cylindrical pleated filter medium (200) (i.e., the height of the cylindrical pleated filter medium (200)) can be 20 to 500 mm, 30 to 400 mm, or 40 to 300 mm.

[0072] In addition, when the cylindrical shape of the cylindrical pleated filter medium (200) is viewed in a direction parallel to a line that can be formed by continuously connecting the apexes of the pleat peaks (A), the diameter of the largest circle that touches the inner circumference of the cylindrical pleated filter medium (200) can be 8 to 500 mm, 15 to 400 mm, or 30 to 500 mm. In addition, the diameter of the circle that touches the outer circumference of the cylindrical pleated filter medium (200) can be 10 to 700 mm, 32 to 600 mm, or 48 to 500 mm. The length obtained by subtracting the diameter of the largest circle that touches the inner circumference from the diameter of the circle that touches the outer circumference and dividing the result by 2 is the pleat peak height of the cylindrical pleated filter medium (200). The pleat peak height can be 1 to 100 mm, 3 to 50 mm, or 5 to 30 mm.

[0073] Next, an example of a method for manufacturing a filter including a cylindrical pleated filter medium according to the present invention will be described below, with the description of the configuration already described being omitted.

[0074] The method for producing a filter including a cylindrical pleated filter medium according to the present invention can be appropriately selected. For example, (Step 1) preparing a filter medium having a nonwoven fabric layer and a fabric layer; (Step 2) folding the opposing ends of the filter material into a zigzag shape; (Step 3) A step of overlapping the opposing ends of the filter material folded into the zigzag shape by providing a layer of an adhesive component capable of forming an adhesive layer between the fabric layers in a state in which the fabric layers face each other, (Step 4) applying pressure or heat and pressure to the overlapped portion of the ends; (Step 5) cooling the part to which heat or heat and pressure has been applied; The method for manufacturing a filter includes a cylindrical pleated filter material formed into a hollow cylindrical shape by bonding the opposing ends of the filter material folded into a zigzag shape, In the step 3, the thickness of the adhesive layer is at least twice the thickness of the fabric layer. It can be.

[0075] In (Step 1), the lamination state of the nonwoven fabric layer and the cloth layer in the prepared filter medium can be appropriately adjusted. The filter medium may be a filter medium in which both layers are simply laminated, a filter medium in which both layers are bonded together with a binder, or a filter medium in which both layers are bonded together by welding the constituent fibers of the nonwoven fabric layer and / or the cloth layer.

[0076] The filter medium may also be subjected to secondary processing such as punching or cutting into a desired shape such as a rectangle, adjusting the thickness, or embossing.

[0077] In (Step 3), the method of forming the adhesive layer (21) can be adjusted as appropriate, but it can be formed by providing a layer of an adhesive component capable of forming the adhesive layer (21) on the exposed main surface of the fabric layer (2) at the end (12) of the filter medium. Specific examples of providing a layer of an adhesive component include a method of applying a solution or dispersion containing an adhesive component to the exposed main surface of the fabric layer (2), a method of applying a molten adhesive component to the exposed main surface of the fabric layer (2) at the end (12) of the filter medium, a method of placing a hot melt web composed of an adhesive component on the exposed main surface of the fabric layer (2) at the end (12) of the filter medium, and a method of placing a double-sided tape containing an adhesive component on the main surface of the fabric layer (2) at the end (12) of the filter medium.

[0078] In addition, as the layer of adhesive component to be provided on the exposed main surface of the fabric layer (2) at the end (12) of the filter material, a method of applying molten adhesive component or a solution or dispersion of the adhesive component so as to form a layer of adhesive component having a thickness of at least twice the thickness of the fabric layer (2), or preferably a method of providing a double-sided tape having a thickness of at least twice the thickness of the fabric layer (2), can be used.

[0079] In particular, by adopting a method of providing double-sided tape having a thickness equal to or greater than twice the thickness of the fabric layer (2), the opposing ends (12) of the tubular pleated filter material (200) are firmly bonded to each other, and the elongation of the portion (20) where the ends (12) are bonded to each other can be improved.

[0080] Therefore, even if an external force acts on the cylindrical pleated filter material (200), the portion (20) can easily stretch and follow the external force, so that a filter can be manufactured that includes a cylindrical pleated filter material (200) whose ends (12) are unlikely to come apart.

[0081] In addition, by using a double-sided tape to form the adhesive layer (21), a filter including a cylindrical pleated filter medium (200) can be manufactured with good productivity. As such a double-sided tape, a double-sided tape having layers of adhesive components on both main surfaces of a substrate such as paper, film, or fabric, or a double-sided tape consisting only of adhesive components can be used. In particular, it is preferable to use a double-sided tape consisting only of adhesive components, since it is possible to provide a filter including a cylindrical pleated filter medium (200) in which the portion (20) is easily stretched and can follow the external force even when an external force is applied, and the ends (12) are unlikely to come apart from each other.

[0082] In (step 4), pressure or heat and pressure are applied to the overlapping portion of the ends. The method can be adjusted as appropriate, and for example, a method of applying pressure using a clip, a method of applying pressure using a press machine, a method of applying heat and pressure by using a heat sealer, a method of applying heat and pressure by using an ultrasonic welder, etc. can be used. In this step, by applying heat to the overlapping portion of the ends, the solvent or dispersion medium contained in the solution or dispersion liquid containing the adhesive component can be removed, and / or the adhesive component can be melted.

[0083] After this step, a step of cooling the part to which pressure or heat and pressure have been applied may be performed. The cooling method can be appropriately adjusted, and may include a method of leaving the part to cool at room temperature, a method of cooling in a refrigerator, a method of applying cold air, a method of applying a member such as a cooled plate or roller, or the like.

[0084] The cylindrical pleated filter medium (200) prepared as described above may be used as a filter as it is, or a filter may be prepared by providing end plates (not shown) at both ends of the cylindrical pleated filter medium (200), inserting a cylindrical support having holes into the cylindrical interior of the cylindrical pleated filter medium (200), and / or providing a cylindrical support having holes that covers the outer peripheral surface of the cylindrical pleated filter medium (200). The method for bonding the cylindrical pleated filter medium (200) to the end plates or support can be appropriately selected from general bonding methods, such as using an adhesive component having the above-mentioned adhesive component or bonding using double-sided tape. EXAMPLES

[0085] The present invention will be specifically described below with reference to examples, but the scope of the present invention is not limited thereto.

[0086] (Preparing filter media) Glass fiber nonwoven fabric (average fiber diameter: 1.6 μm, basis weight: 70 g / m) prepared by wet papermaking of glass fibers. 2 , thickness: 0.38 mm) was prepared. In addition, a polypropylene fiber net (wire diameter: 0.2 mm, opening shape: rectangular with a mesh size of 0.6 mm on the short side and 0.8 mm on the long side, basis weight: 50 g / m 2 , thickness: 0.3 mm) was prepared. Then, a polypropylene fiber net was simply laminated on one main surface of the glass fiber nonwoven fabric to create a filter medium (weight: 120 g / m 2 , thickness: 0.68 mm, thickness of the net-derived fabric layer: 0.3 mm) were prepared.

[0087] (Method of preparing filter media folded in a zigzag shape) A rectangular sample (long side: 240 mm, short side: 120 mm) was taken from the filter material. The ends of the collected sample having opposing short sides were folded into a zigzag shape. The zigzag folded filter medium had a pleat height of 6 mm.

[0088] Comparative Example 1 A double-sided tape (thickness: 0.4 mm) made only of acrylic resin was prepared. Of the opposing ends of the filter medium folded into a zigzag shape, double-sided tape was applied to the entire exposed surface of the net constituting one end. Then, the exposed net was placed on the other end of the zigzag-folded filter medium, with the double-sided tape between them. As a result, as shown in FIG. 3, the net-derived fabric layers were placed on top of each other with the double-sided tape between them. By applying pressure to the overlapping portions, i.e., portions having a layered configuration of nonwoven fabric layer derived from glass fiber nonwoven fabric-fabric layer derived from net-double-sided tape-fabric layer derived from net-nonwoven fabric layer derived from glass fiber nonwoven fabric, the ends were adhered together with double-sided tape to prepare a cylindrical pleated filter medium (height: 120 mm, diameter of largest circle touching inner circumference: 15 mm, diameter of circle touching outer circumference: 27 mm, pleat peak height: 6 mm). In the cylindrical pleated filter medium thus prepared, in the portion where the opposing ends are bonded together by the adhesive layer, the adhesive layer does not exist on the line segment that connects the nonwoven fabric layer of one of the opposing ends with the nonwoven fabric layer of the other of the opposing ends at the shortest distance, and the adhesive layer does not exist on another line segment.In addition, in this portion, the thickness of the two layers of fabric was 0.6 mm, while the thickness of the adhesive layer derived from the double-sided tape was thinner (thicker than 0.4 mm and thinner than 0.6 mm).

[0089] Example 1 A double-sided tape (thickness: 0.8 mm) made only of acrylic resin was prepared. A cylindrical pleated filter medium was prepared in the same manner as in Comparative Example 1, except that the double-sided tape thus prepared was used. In the cylindrical pleated filter medium thus prepared, in the portion where the opposing ends are bonded together by the adhesive layer, the adhesive layer exists on the line segment that connects the nonwoven fabric layer of one of the opposing ends with the nonwoven fabric layer of the other of the opposing ends at the shortest distance and on another line segment. In addition, in this portion, the thickness of the two fabric layers was 0.6 mm, while the thickness of the adhesive layer derived from the double-sided tape was thicker (thicker than 0.8 mm).

[0090] Example 2 A polyurethane emulsion adhesive was applied to the entire exposed surface of the net constituting one of the opposing ends of the filter medium that had been folded into a zigzag shape. Then, the exposed net was overlapped with the exposed net constituting the other end of the opposing ends of the filter medium folded into a zigzag shape. As a result, as shown in Figure 3, the fabric layers derived from the net were overlapped so that they faced each other with the polyurethane emulsion adhesive between them, which was made by dispersing polyurethane resin in a dispersion medium. Pressure was applied to the overlapping portions, i.e., the portions having a laminated configuration of two layers of nonwoven fabric layer-woven fabric layer and a layer containing polyurethane emulsion adhesive-nonwoven fabric layer, and then the portions were dried to bond the ends together with the polyurethane emulsion adhesive, thereby preparing a cylindrical pleated filter medium (height: 120 mm, diameter of largest circle touching the inner circumference: 15 mm, diameter of circle touching the outer circumference: 27 mm, pleat height: 6 mm). In the cylindrical pleated filter medium thus prepared, in the portion where the opposing ends are bonded together by the adhesive layer, the adhesive layer exists on the line segment that connects the nonwoven fabric layer of one of the opposing ends with the nonwoven fabric layer of the other of the opposing ends at the shortest distance and on another line segment. In addition, in this portion, the thickness of the two fabric layers was 0.6 mm, while the thickness of the adhesive layer derived from the polyurethane emulsion adhesive was thicker (thicker than 1.0 mm).

[0091] Example 3 A double-sided tape (thickness: 1.2 mm) made only of acrylic resin was prepared. A cylindrical pleated filter medium was prepared in the same manner as in Comparative Example 1, except that the double-sided tape thus prepared was used. In the cylindrical pleated filter medium thus prepared, in the portion where the opposing ends are bonded together by the adhesive layer, the adhesive layer exists on the line segment that connects the nonwoven fabric layer of one of the opposing ends with the nonwoven fabric layer of the other of the opposing ends at the shortest distance and on another line segment. In addition, in this portion, the thickness of the two fabric layers was 0.6 mm, while the thickness of the adhesive layer derived from the double-sided tape was thicker (thicker than 1.2 mm).

[0092] In the cylindrical pleated filter media prepared in Examples 1 to 3, the acrylic resin (Examples 1 and 3) or polyurethane resin (Example 2) was present between the nonwoven fabric layers in all the areas where the fabric layers faced each other, and penetrated into the insides of both nonwoven fabric layers. As a result, the adhesive layer made of the acrylic resin or polyurethane resin not only bonded the fabric layers together, but also bonded the fabric layers to the nonwoven fabric layers and the nonwoven fabric layers together.

[0093] The physical properties of each cylindrical pleated filter medium prepared as described above were measured by the following methods. The measurement results are summarized in Table 1.

[0094] (Method of measuring collection efficiency) A cylindrical pleated filter medium was cut along a line that could connect the apexes of one pleat mountain to form a continuous filter medium, and a filter medium folded into a zigzag shape was prepared. At this time, the pleat mountain was selected to be cut along the line so that the part where the ends were bonded together by the adhesive layer was located in the center of the filter medium folded into a zigzag shape. The mountain folds and valley folds were then straightened out to prepare a flat filter medium having a rectangular shape when viewed from above the main surface. Note that the short side direction of the flat filter medium is parallel to the lines. Next, a test duct with a circular opening (effective opening area: 0.01 m) was 2 A flat filter medium was placed on the test duct so as to cover the entire opening. At this time, the fabric layer side was in contact with the test duct, and the part where the ends were bonded to each other by the adhesive layer was folded so as to overlap the main surface of the flat filter medium, and the overlapping part was placed at the center of the duct. Then, calculate the collection efficiency (%) by counting method. That is, after setting the flat filter medium in the holder of the test duct with an effective opening area of ​​0.01m2, supply NaCl (NaCl number: U) with particle diameter of 0.3μm to the upstream side (non-woven fabric layer side of the flat filter medium) of the flat filter medium, and when air is passed through at a surface velocity of 5.3cm / s, measure the number (D) of NaCl with particle diameter of 0.3μm on the downstream side (fabric layer side of the flat filter medium) with a particle counter (RION Co., Ltd.: Model KC-22B), and calculate the value according to the following formula as the initial NaCl efficiency (unit:%). NaCl initial efficiency = [1-(D / U)] x 100 Furthermore, cylindrical pleated filter media with high calculated values ​​are less likely to peel off at the parts where the ends are bonded together by the adhesive layer, even when exposed to wind force (external force) during the measurement, meaning that leakage of the NaCl to be filtered is less likely to occur.

[0095] (Method for measuring adhesive strength between opposing ends) A sample (long side: 228 mm (parallel to the long side of the flat filter material), short side: 50 mm (parallel to the short side of the flat filter material)) was taken from the flat filter material (long side: 228 mm, short side: 120 mm rectangular shape) prepared by the above-mentioned (method of measuring collection efficiency). The flat filter material was fixed to the chuck of a constant-speed extension tensile tester (Tensilon, manufactured by Orientec Co., Ltd.) so that the part where the ends are bonded to each other by the adhesive layer is between the chucks (distance between chucks: 100 mm). Then, the long side direction of the flat filter material and the pulling direction by the constant-speed extension tensile tester were parallel, and the ends were pulled at a speed of 100 mm / min until they came off. Then, the maximum stress (unit: N / 50 mm) measured until the ends came off was obtained, and was taken as the adhesive strength (unit: N / 50 mm). In addition, a cylindrical pleated filter medium with a high adhesive strength (unit: N / 50 mm) means that even when an external force is applied, peeling is unlikely to occur at the parts where the ends are bonded together by the adhesive layer.

[0096] (Method for measuring elongation at the part where opposing ends are bonded) In the above (method of measuring the adhesive strength between opposing ends), the length (unit: mm) of the flat filter medium stretched is calculated by subtracting the length (100 mm) between the chucks at the beginning of the measurement from the distance (unit: mm) between the chucks when the ends are separated.Then, the calculated length of the flat filter medium stretched is divided by the length (100 mm) between the chucks at the beginning of the measurement and multiplied by 100 to obtain the elongation (unit: %).

[0097] [Table 1]

[0098] From the results of comparing Comparative Example 1 with Examples 1 to 3, it was found that in the portion where the opposing ends are bonded together by the adhesive layer, the adhesive layer is present on the line segment connecting the nonwoven fabric layer at one of the opposing ends and the nonwoven fabric layer at the other opposing end by the shortest distance and / or on another line segment, thereby making it possible to provide a filter in which the ends are firmly bonded together.

[0099] In particular, the results of comparing Example 1 and Example 3 with Example 2 reveal that a filter having improved elongation at the portion where the ends are bonded together can be provided by manufacturing a filter having a cylindrical pleated filter medium by overlapping the ends together using a double-sided tape having a thickness of at least two layers of fabric. As a result, by using the cylindrical pleated filter medium according to the present invention, a filter having a cylindrical pleated filter medium whose ends are difficult to come apart can be provided.

[0100] From the above, it has been found that the present invention can provide a filter including a cylindrical pleated filter medium in which opposing ends of the filter medium are preferably bonded to each other. [Industrial Applicability]

[0101] The filter of the present invention can be suitably used as a gas filter or liquid filter in, for example, food or medical product production factories, precision equipment manufacturing factories for batteries or other such equipment, indoor cultivation facilities for agricultural crops, general households or industrial facilities such as hospitals and office buildings, electrical appliances such as air purifiers and office automation equipment, and various vehicles such as automobiles and aircraft. Another method of utilizing the filter material used in the present invention, in which the opposing ends are folded into a zigzag shape, is to place the filter material in, for example, a rectangular filter frame and bond the contact points between the filter material and the filter frame together with an adhesive layer made of double-sided tape or the like, thereby preparing a flat filter unit. When a filter frame having a fabric layer on one main surface (a filter frame that is breathable in the thickness direction, or a filter frame that is not breathable in the thickness direction) is used, a flat filter unit can be prepared in which the fabric layer side at the end of the filter material is bonded to the fabric layer side present on the main surface of the filter frame with an adhesive layer made of double-sided tape or the like. At this time, the fabric layer of the filter medium, the opposing ends of which are folded into a zigzag shape, and the fabric layer provided on one of the main surfaces of the filter frame face each other, and the two fabric layers are bonded to each other by an adhesive layer. On a line segment that connects, at the shortest distance, the nonwoven fabric layer of the filter medium and a component on the opposite side of the fabric layer to the side facing the filter medium, such as a metal frame of the filter frame, and / or - On another line segment that is parallel to the line segment and connects a nonwoven fabric layer of the filter medium and a component member, such as a metal frame of the filter frame, on the opposite side of the fabric layer facing the filter medium, The adhesive layer is present throughout the entire area. As a result, a flat filter unit can be easily prepared in which the fabric layer of the filter medium and the fabric layer of the filter frame are firmly bonded to each other by the adhesive layer at the contact points between the filter medium and the filter frame. [Explanation of symbols]

[0102] 100: Pleated filter media 1: Non-woven layer 2:Fabric layer 11: Opposite sides 12: Opposite ends 3: Plate with a flat main surface A: Pleated mountain B: Pleated Valley C: Pleats height D1: The shortest distance between adjacent pleats D2: The shortest distance between adjacent pleat valleys 200: Cylindrical pleated filter media 20: The part where the opposing ends are bonded together by an adhesive layer 21: Adhesive layer 1a: Nonwoven fabric layer provided at one of the opposing ends 1b: Nonwoven fabric layer provided at the other of the opposing ends 2a: Fabric layer provided at one of the opposing ends 2b: Fabric layer provided at the other of the opposing ends E: Line segment Fa: Thickness of one fabric layer Fb: thickness of the other fabric layer

Claims

1. A filter comprising a cylindrical pleated filter medium, the opposing ends of which are folded in a zigzag shape, and the opposing ends are bonded together to form a hollow cylindrical shape, The filter medium comprises a nonwoven fabric layer and a fabric layer, The fabric layers are faced to each other, and the facing ends are bonded to each other by an adhesive layer, In a portion where the opposing ends are bonded to each other by an adhesive layer, the adhesive layer is present on a line segment that connects the nonwoven fabric layer of one of the opposing ends to the nonwoven fabric layer of the other of the opposing ends at the shortest distance, and / or on another line segment that is parallel to the line segment and connects the nonwoven fabric layer of one of the opposing ends to the nonwoven fabric layer of the other of the opposing ends. filter.

2. (Step 1) preparing a filter medium having a nonwoven fabric layer and a fabric layer; (Step 2) folding the opposing ends of the filter material into a zigzag shape; (Step 3) A step of overlapping the ends of the filter material folded into the zigzag shape by providing a layer of an adhesive component capable of forming an adhesive layer between the fabric layers in a state in which the fabric layers face each other; (Step 4) applying pressure or heat and pressure to the overlapped portion of the ends; The method for manufacturing a filter includes a cylindrical pleated filter material formed into a hollow cylindrical shape by bonding the opposing ends of the filter material folded into a zigzag shape, The method for producing a filter, wherein in the step (3), the thickness of the layer of the adhesive component is at least twice the thickness of the fabric layer.

3. The method for producing a filter according to claim 2, wherein the layer of adhesive component is a double-sided tape.

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