JP6043590B2 - Filter media and filter unit - Google Patents

Description

  The present invention relates to a filter medium that collects particles contained in a gas to be filtered and a filter unit that uses the filter medium, and particularly relates to a filter material that can collect the particles that is pleated.

  Conventionally, a filter medium 100 as shown in FIG. 6 is known as a filter medium used in a clean room of a factory for manufacturing semiconductors and liquid crystals. The filter medium 100 is formed by bending a filter medium original fabric 200 configured to collect particles contained in a gas to be filtered at a plurality of locations into a bowl shape.

  Such a filter medium 100 has a plurality of flat plate portions 100b formed so that a bent portion 100a formed by bending the filter medium original fabric 200 and an area other than the bent portion 100a in the filter medium original fabric 200 are opposed to each other. And a plurality of interval holding portions 300 that hold intervals between adjacent flat plate portions 100b, 100b.

  The interval holding part 300 is formed of a plurality of bead parts 300 a formed by applying an adhesive (hot melt or the like) at an interval to both surfaces of the filter medium original fabric 200. Specifically, the interval holding unit 300 is configured so that each of the bead portions 300a and 300a on one surface side and the other surface side is between the flat plate portions 100b on one surface side and the other surface side of the filter medium original fabric 200. Is formed by bonding. That is, the interval holding unit 300 is formed between the flat plate portions 100 b on one surface side and the other surface side of the filter medium original fabric 200.

  As shown in FIG. 7A, the filter medium 100 configured as described above is accommodated in a frame A configured to be able to accommodate the filter medium, and constitutes a filter unit 110. The frame A includes a pair of opposing walls A1 and A1 that are arranged to face each other with a space therebetween, and a connecting wall A2 that connects the outer peripheral portions of the pair of opposing walls A1 and A1. The filter medium 1 can be accommodated in a space AR (hereinafter also referred to as an internal space) AR surrounded by a pair of opposing walls A1, A1 and a connecting wall A2. The pair of opposed walls A1, A1 includes openings A3, A3 that communicate with the internal space AR. Thereby, the frame A is configured so that the gas to be filtered can pass through the internal space AR from the one opening A3 side toward the other opening A3 side.

  The filter medium 100 accommodated in the frame A is disposed on the one opposing wall A1 side in the internal space AR, and the outer peripheral portion is fixed to the frame A. Thereby, the space | interval is formed between the filter medium 100 and the other opposing wall A1.

  The filter unit 110 configured as described above is arranged so that the length L1 direction of the filter medium 100 intersects (specifically, substantially orthogonal) with the flow direction F of the gas to be filtered. That is, the filter unit 110 is arranged so that the gas to be filtered contacts the filter medium 100 from the height L3 direction of the filter medium 100. As a result, the gas to be filtered flowing into the filter unit 110 from one opening A3 of the frame A permeates the filter medium 100 in the internal space AR and is discharged from the other opening A3 of the frame A. become.

  For this reason, when the gas to be filtered is circulated through the filter unit 110, the central portion of the filter medium 100 is covered by the wind pressure of the gas to be filtered and the pressure loss of the filter medium 100 as shown in FIG. There is a possibility that the filter medium 100 bulges toward the downstream side in the flow direction F of the filtered gas and the filter medium 100 is curved.

  Such a curvature of the filter medium 100 increases the pressure loss of the filter unit or decreases the filtration efficiency. Moreover, if the curve of the filter medium 100 becomes too large, the filter unit 110 may be damaged.

  Various methods have been proposed as a method for preventing the filter medium from bending as described above. For example, by reducing the initial pressure loss of the filter medium raw material constituting the filter medium or by increasing the effective area of the filter medium, the increase in the pressure loss over time of the filter medium is reduced and is caused by wind pressure. A method for suppressing the curvature of the filter medium has been proposed (see Patent Document 1). Further, a method has been proposed in which a member having higher rigidity than the filter medium (hereinafter also referred to as a rigid member) is attached to the filter medium, and the curve of the filter medium is suppressed by the rigid member (see Patent Documents 2 and 3).

JP 2002-292215 A JP 11-42410 A International Publication No. 2005/077492 Pamphlet

  However, as described above, in the method of reducing the increase in the pressure loss of the filter medium over time, there is a possibility that the performance of collecting particles from the gas to be filtered is lowered. In addition, as described above, the method using a rigid member requires a cost for preparing the rigid member, and takes time when producing a filter medium and a filter unit, which causes a reduction in production efficiency.

  Then, this invention makes it a subject to provide the filter unit which can prevent that it deform | transforms unintentionally with the wind pressure of to-be-filtered gas, and the filter unit using this filter medium.

In the filter medium according to the present invention, a plurality of bent parts formed by bending a filter medium raw material capable of collecting particles contained in a gas to be filtered in a bowl shape, and regions other than the bent parts in the filter medium raw material face each other. A plurality of flat plate portions that are arranged and formed, and a plurality of flat plate portions that are formed between the respective flat plate portions on one surface side and the other surface side of the filter medium original fabric and that maintain the spacing between adjacent bent portions. A filter medium comprising an interval holding unit,
The gap holding part is formed by applying an adhesive to one surface of the filter medium original fabric and the other surface side bead formed by applying an adhesive to the other surface of the filter medium original fabric. Each part is formed by joining between flat plate parts,
The one surface side bead portion and the other surface side bead portion are formed on the surface on the mountain side of the bent portion in the filter medium original fabric,
The filter medium original fabric is configured such that the thickness of the portion forming the interval holding portion in the other surface side bead portion is thinner than the thickness of the portion forming the interval holding portion in the one surface side bead portion. Of the interval holding portions formed on both sides of the filter medium, the other surface side interval formed on the other surface side of the filter medium original fabric rather than the thickness of the one surface side interval holding portion formed on one surface side of the filter media original fabric It is configured so that the thickness of the holding part is thinner ,
A curved radius is formed so as to be 290 mm or more and 1200 mm or less .

  According to such a structure, the space | interval of the flat plate parts in the other surface side of a filter-medium original fabric becomes narrower than the space | interval of the flat-plate parts in the one surface side of a filter-medium original fabric. For this reason, the area | region of the center side rather than the both ends of the length direction of a filter medium becomes easy to bulge to the one surface side of a filter medium original fabric, and it becomes easy to curve a filter medium. Thus, it can suppress that a filter medium is deform | transformed with the wind pressure of to-be-filtered gas by using a filter medium in the curved state.

  Specifically, when the filter medium is curved as described above, the rigidity of the filter medium increases with respect to the wind pressure applied to the filter medium from the side where the central region of the filter medium swells. For this reason, the deformation of the filter medium due to the wind pressure can be suppressed.

Moreover, it is preferable that the ratio of the mass of the said one surface side bead part with respect to the mass of the said other surface side bead part is 1.2 or more and 2.1 or less .

  Moreover, it is preferable that the thickness of the site | part which forms the space | interval holding | maintenance part in the said one surface side bead part is 20 to 80% of the thickness of the site | part which forms the space | interval holding part in the other surface side bead part.

  A filter unit according to the present invention is a filter unit in which the filter medium is accommodated in a frame body that accommodates the filter medium according to any one of the above, and the frame body allows a gas to be filtered to flow inside. The filter medium is provided with an opening, and the filter medium is curved and accommodated in the frame so that a region on the center side of both ends in the length direction is located on the opening side.

  As described above, according to the present invention, unintentional deformation due to the wind pressure of the gas to be filtered can be prevented.

The perspective view which showed the filter material which concerns on this embodiment. The perspective view which showed the filter-medium original fabric which concerns on the filter medium of the embodiment, and its partially expanded view. (A) is sectional drawing which cut | disconnected the filter medium of the same embodiment in the surface which cross | intersects a flat plate part along a height direction, (b) cut | disconnects the filter medium in the surface along the length direction and the width direction. FIG. Sectional drawing of the filter unit comprised using the filter medium which concerns on the embodiment. Sectional drawing which showed the space | interval holding | maintenance part of the filter material which concerns on other embodiment. The perspective view which showed the conventional filter medium. 6A is a cross-sectional view of a filter unit in which the filter medium of FIG. 6 is housed in a frame, and FIG. 6B is a state in which the filter medium is curved by applying the wind pressure of the gas to be filtered to the filter unit of FIG. FIG.

  Hereinafter, embodiments of the present invention will be described with reference to FIGS. In the following drawings, the same or corresponding parts are denoted by the same reference numerals, and description thereof will not be repeated.

  In the filter medium 1 according to the present embodiment, as shown in FIG. 1, a filter medium original fabric 2 configured to collect particles contained in a gas to be filtered is bent in a bowl shape (hereinafter also referred to as pleating). A plurality of bent portions 1a formed, a plurality of flat plate portions 1b formed so as to face areas other than the bent portion 1a in the filter medium original fabric 2, and one surface side of the filter media original fabric 2 and A plurality of interval holding portions 3A and 3B that are formed between the flat plate portions 1b on the other surface side and hold the interval between the adjacent bent portions 1a and 1a are provided.

  As shown in FIG. 2, the filter medium original fabric 2 is formed in a sheet shape in which one direction is a longitudinal direction before being bent into a bowl shape. In addition, the filter medium original fabric 2 may be configured to be formed into a sheet shape by being unwound from a state where it is formed in a long shape so that one direction is a longitudinal direction, and one direction is a longitudinal direction. The sheet body formed in the sheet form so that it may become.

  Moreover, the filter medium original fabric 2 includes a porous layer 2a that collects particles contained in the gas to be filtered, and a base material layer 2b that has air permeability and is laminated on the porous layer 2a. In the present embodiment, the filter medium original fabric 2 includes a plurality of (specifically, two) porous layers 2a, and the base material layer 2b is disposed between the porous layers 2a. Thus, by forming the filter medium original fabric 2 using a plurality of porous layers 2a, pressure loss and collection efficiency are higher than when the filter media original fabric 2 is formed from a single porous layer 2a. It is possible to suppress the occurrence of variations. Moreover, since it can suppress that a pinhole which penetrates the filter-medium original fabric 2 is formed, the filter-medium original fabric 2 of a leakless structure can be obtained.

  The porous layer 2a is formed using a porous sheet material (hereinafter also referred to as a porous sheet) capable of collecting the particles. The porous sheet is not particularly limited, and can be appropriately selected depending on the use of the filter medium 1. For example, a PTFE sheet in which polytetrafluoroethylene (PTFE) is formed in a sheet shape, a melt blown nonwoven fabric, an electret filter, glass fiber, or the like can be used. In the present embodiment, a PTFE sheet is used as the porous sheet. As a method for forming the PTFE sheet, for example, the following method can be employed.

  Specifically, a liquid lubricant is added to the PTFE fine powder to form a paste-like mixture. The PTFE fine powder is not particularly limited. For example, Polyflon F-104 (manufactured by Daikin Industries), Fullon CD-123 (manufactured by Asahi ICI Fluoropolymers), Teflon 6J (Mitsui / Dupont Fluorochemical) Etc.) can be used. The liquid lubricant is not particularly limited as long as it can impart appropriate wettability to the surface of the mixture, and is particularly preferable if it can be removed by extraction treatment or heat treatment. For example, in addition to hydrocarbon oils such as liquid paraffin, naphtha, white oil, toluene, and xylene, alcohols, ketones, esters, and mixtures of two or more of these can be used as the liquid lubricant. The addition amount of the liquid lubricant is not particularly limited, but is appropriately adjusted according to the type of PTFE fine powder and liquid lubricant, and the molding method when obtaining the PTFE sheet. Specifically, the addition amount of the liquid lubricant is preferably 5 parts by mass or more and 50 parts by mass or less with respect to 100 parts by mass of the PTFE fine powder.

  And the said mixture which consists of PTFE fine powder and a liquid lubricant is preformed, and a preformed body is produced. Specifically, a preform is produced by extruding the mixture into a rod shape. Such preforming is preferably performed at a pressure that does not separate the liquid lubricant from the mixture.

  Next, the obtained preform is formed into a sheet by extrusion or rolling. Specifically, a preform is supplied between a pair of roller members and rolled to form a sheet, a method of extruding into a sheet, or a pair of extrudates formed into a sheet. Examples of the method include a method of forming a sheet by feeding between rollers and rolling. The thickness of the obtained sheet-like molded body is not particularly limited, and is preferably 0.05 mm or more and 0.5 mm or less, for example.

  Next, the obtained sheet-like molded body is made uniaxially stretched or biaxially stretched to obtain a PTFE sheet. In the present embodiment, the sheet-like molded body is stretched along the longitudinal direction and is also stretched along the width direction orthogonal to the longitudinal direction (biaxial stretching). In addition, before extending | stretching a sheet-like molded object, it is preferable to remove a liquid lubricant from this molded object. As a method of removing the liquid lubricant, a method of heating the molded body (heating method) or a method of extracting the liquid lubricant by immersing the molded body in a solvent (extraction method) can be employed.

  When the sheet-like molded body is stretched along the longitudinal direction, fibrillation of the molded body is easily promoted to become porous when the stretch ratio is large. For example, the stretch ratio is 10 times or more. It is preferably 30 times or less. Moreover, it does not specifically limit as temperature conditions at the time of extending | stretching this molded object, For example, it is preferable that it is 150 to 327 degreeC.

  By stretching the sheet-like molded body after being stretched along the longitudinal direction along the width direction, the molded body can be effectively fibrillated, and a PTFE sheet with less variation in pore diameter can be obtained. it can. The conditions for stretching the sheet-like molded body along the width direction are not particularly limited. For example, the stretching ratio is preferably 20 times or more and 100 times or less. Further, it is preferable to stretch the sheet-like molded body along the width direction so that the area stretch ratio represented by the product of the stretch ratio at the time of stretching in the longitudinal direction is 450 times or more. Fibrilization is further promoted as the area stretch ratio is larger, and a porous PTFE sheet having a large PF value can be obtained. Moreover, it does not specifically limit as extending | stretching temperature, For example, it is preferable that it is 40 to 100 degreeC.

The PTFE sheet formed as described above has excellent characteristics such that the pressure loss is 50 mmH ₂ O or less and the collection efficiency is 99.9% or more. In particular, when the area stretch ratio is 450 times or more, the pressure loss can be reduced to less than 20 mmH ₂ O without greatly reducing the collection efficiency, and the PF value is 22 or more, which is extremely excellent. It becomes a porous PTFE sheet of performance. Further, the variation in pressure loss for each obtained PTFE sheet is reduced. For this reason, it becomes a porous PTFE sheet which has low operating costs and exhibits extremely excellent dust removal performance.

Note that the PTFE sheet obtained as described above may be further subjected to heat treatment (firing treatment) for the purpose of increasing strength and dimensional stability. The heat treatment of the PTFE sheet is generally performed with the dimensions fixed at a temperature equal to or higher than the melting point of the PTFE fired body. Moreover, it becomes possible to reduce a pressure loss by such heat processing. For this reason, when the PF value of the PTFE sheet is 22 or more and the pressure loss is 20 mmH ₂ O or more, the heat loss can be reduced to less than 20 mmH ₂ O by this heat treatment.

  The base material layer 2b is formed using a breathable sheet material (hereinafter also referred to as a breathable sheet). The breathable sheet is not particularly limited, and for example, a nonwoven fabric, a woven fabric, a mesh, a polymer fiber, or the like can be used. In particular, when the porous layer 2a (porous layer sheet) and the base material layer 2b (breathable sheet) are thermally welded (heat laminated), it is preferable to use a breathable sheet made of a thermoplastic material. .

  Examples of the material of the breathable sheet include polyolefins such as polyethylene and polypropylene, nylon, polyester, aramid (specifically, aromatic polyamide), or a composite of these (for example, core / sheath structure). And a non-woven fabric made of fibers and a two-layer non-woven fabric of a low melting point material and a high melting point material). In addition, examples of the material of the air-permeable sheet include fluorine such as PFA (tetrafluoroethylene / perfluoroalkyl vinyl ether copolymer), FEP (tetrafluoroethylene / hexafluoropropylene copolymer), and a porous film of PTFE. System porous membranes.

  In particular, a core-sheath composite fiber having a core component having a relatively higher melting point than the sheath component, a non-woven fabric composed of synthetic fibers, a non-woven fabric composed of two layers of a low melting point material and a high melting point material, and the like. Is preferably used. By using such a nonwoven fabric, when the porous layer 2a (porous layer sheet) and the base material layer 2b (breathable sheet) are heat-laminated, the shrinkage of the base material layer 2b is suppressed. Is possible. Moreover, by using such a nonwoven fabric, the workability at the time of pleating becomes favorable, and it becomes possible to increase the locations (folding pitch) where the filter medium raw fabric 2 is bent.

  The method of forming the filter medium raw fabric 2 as described above is not particularly limited, and for example, between the porous sheet that forms the porous layer 2a and the breathable sheet that forms the base material layer 2b. It is possible to employ a method in which a hot melt or pressure sensitive adhesive is disposed on the porous sheet and the porous sheet and the breathable sheet are pressure-bonded. Alternatively, it is possible to employ a method in which a breathable sheet is heated and softened to be pressure-bonded (thermally laminated) to the porous sheet.

  In the filter medium original fabric 2 configured as described above, bead portions 3a and 3b for forming the interval holding portions 3A and 3B are formed. The bead portions 3a and 3b are formed after the filter medium original fabric 2 is pleated. Specifically, after the filter medium original fabric 2 is bent and pleated at a plurality of locations along the width direction orthogonal to one direction (longitudinal direction), the filter medium original is stretched to a flat state before pleating. The bead portions 3a and 3b are formed by applying an adhesive on both sides of the opposite side. The shape of the bead portions 3a and 3b is not particularly limited, and in this embodiment, the bead portions 3a and 3b are formed linearly along one direction (longitudinal direction) of the filter medium original fabric 2.

  A bead portion (hereinafter also referred to as one surface side bead portion) 3a formed on one surface side of the filter medium original fabric 2 and a bead portion (hereinafter referred to as other surface side bead) formed on the other surface side of the filter media original fabric 2 3b is also formed at a plurality of locations on the filter medium raw fabric 2. Specifically, a plurality of one-side bead portions 3a and other-side bead portions 3b are formed at intervals along one direction (longitudinal direction) of the filter medium original fabric 2. And the one surface side bead portion 3a and the other surface side bead portion 3b are alternately arranged along one direction (longitudinal direction) of the filter medium original fabric 2 (and so as not to overlap with each other through the filter media original fabric 2). Arranged. Further, a plurality (three in the present embodiment) of the one surface side bead portion 3 a and the other surface side bead portion 3 b are arranged at intervals along the width direction of the filter medium original fabric 2.

  The one surface side bead portion 3a and the other surface side bead portion 3b cross (substantially orthogonal) to a region (hereinafter also referred to as a bending planned region) A1 that becomes the bent portion 1a when the filter medium raw fabric 2 is pleated. Formed. Specifically, among the adjacent planned bending regions A1 and A1, one of the planned bending regions A1 and the one surface side bead portion 3a intersect, and the other planned bending region A1 and the other surface side bead portion 3b include Configured to intersect. Moreover, the one surface side bead part 3a and the other surface side bead part 3b are formed on the surface which becomes the mountain side of the bending part 1a in each bending planned area | region A1.

  Further, the one-side bead portion 3a and the other-side bead portion 3b are formed on both sides of a region A2 that becomes the flat plate portion 1b when the filter medium raw fabric 2 is pleated (hereinafter also referred to as a flat plate portion planned region). The Specifically, the one-surface-side bead portion 3a and the other-surface-side bead portion 3b are formed from the intersecting position with the planned bending region A1 to the substantially central portion of the flat plate portion planned region A2.

  Further, the one-surface-side bead portion 3a and the other-surface-side bead portion 3b formed as described above are on the other-surface side with respect to the thickness of the one-surface-side bead portion 3a (specifically, the portion that forms the interval holding portion 3A). The bead portion 3b (specifically, a portion where the interval holding portion 3B is formed) is configured to be thinner. Specifically, the amount of the adhesive applied to the other surface is smaller than the amount of the adhesive applied to the one surface of the filter medium 2, so that the one side bead The other side bead portion 3b is configured to be thinner than the thickness of the portion 3a. The ratio of the thickness of the other surface side bead portion 3b to the thickness of the first surface side bead portion 3a is preferably 20% or more and 80% or less, and more preferably 40% or more and 60% or less. In addition, the thickness of each bead part 3a, 3b means the thickness of the direction corresponded to the thickness direction of the filter-medium original fabric 2 in each bead part 3a, 3b arrange | positioned on both surfaces of the filter-medium original fabric 2. FIG.

  It does not specifically limit as an adhesive agent which comprises the one surface side bead part 3a and the other surface side bead part 3b, For example, a hot melt can be used. The temperature at which the hot melt is applied to the filter medium original fabric 2 varies depending on the components of the hot melt, but is preferably 100 ° C. or higher and 250 ° C. or lower, and more preferably 140 ° C. or higher and 230 ° C. or lower. .

  As described above, the filter medium original fabric 2 on which the bead portions 3a and 3b are formed is bent again at each of the planned bending regions A1 to form a bowl shape. Thereby, as shown to Fig.3 (a), the some bending part 1a and the some flat plate part 1b are formed. Moreover, each bead part 3a, 3b forms space | interval holding | maintenance part 3A, 3B because the site | part located between each flat plate part 1b in both surfaces of the filter-medium original fabric 2 joins. Thereby, the filter medium 1 is formed. When hot melt is used for the adhesive constituting the bead portions 3a and 3b, when the hot melt is softened to such a degree that it can be joined (within the open time), the filter medium raw fabric 2 is re-glazed. It is preferable to form in a shape.

  In the following description, a direction corresponding to one direction (longitudinal direction) of the filter medium original fabric 2 in the filter medium 1 is defined as a length L1 of the filter medium 1. A direction corresponding to the other direction (width direction) of the filter medium original fabric 2 in the filter medium 1 is defined as a width L2 of the filter medium 1. Moreover, the space | interval between the bending part 1a formed so that one surface side of the filter-medium original fabric 2 may become a peak side, and the bending part 1a formed so that the other surface side of the filter-medium original fabric 2 may become a peak side may be set. The height of the filter medium 1 is L3.

  In the filter medium 1 formed as described above, the interval holding portions 3A and 3B are formed on one surface side and the other surface side of the filter medium raw fabric 2, respectively. In addition, each of the interval holding portions 3A and 3B is formed linearly along the height L3 direction of the filter medium 1. Moreover, each space | interval holding | maintenance part (henceforth one surface side space | interval holding | maintenance part) 3A of filter filter medium 1 and each space | interval holding | maintenance part (henceforth the other surface side space | interval holding | maintenance part) 3B, as shown in FIGS. 3A and 3B, the filter media 1 are alternately arranged along the length L1 direction of the filter medium 1 (specifically, on a straight line along the length L1 direction).

  Further, the one surface side interval holding portion 3A and the other surface side interval holding portion 3B are formed to have different thicknesses. Specifically, it is formed so that the thickness of the other surface side interval holding portion 3B is thinner than the thickness of the one surface side interval holding portion 3A. More specifically, the portions located between the flat plate portions 1b of the other surface side bead portion 3b that is thinner than the first surface side bead portion 3a are joined together, so that the thickness is smaller than that of the first surface side interval holding portion 3A. A direction-side interval holding portion 3B is formed. The ratio of the thickness of the other surface side interval holding portion 3B to the thickness of the one surface side interval holding portion 3A is preferably 20% or more and 80% or less, and more preferably 40% or more and 60% or less. In addition, the thickness of each space | interval holding | maintenance part 3A, 3B means the thickness of the direction corresponded to the direction where adjacent flat plate parts oppose.

  As shown in FIGS. 3A and 3B, the thickness of the other surface side space holding portion 3B is thus made thinner than the thickness of the one surface side space holding portion 3A. The interval between the flat plate portions 1b on the other surface side of the filter medium original fabric 2 is narrower than the interval between the flat plate portions 1b on the one surface side of the filter media original fabric 2.

  As shown in FIG. 4, the filter medium 1 configured as described above is accommodated in a frame body X configured to accommodate the filter medium 1 and used as a filter unit 10. The frame body X includes a pair of opposing walls X1 and X1 disposed so as to face each other with a space therebetween, and a connecting wall X2 that connects the outer peripheral portions of the pair of opposing walls X1 and X1. And it is comprised so that the filter medium 1 can be accommodated in the space (henceforth internal space) XR enclosed by a pair of opposing wall X1, X1 and the connection wall X2. The pair of opposed walls X1, X1 includes openings X3, X3 that communicate with the internal space XR. Thus, the frame body X is configured such that the gas to be filtered can pass through the internal space XR from the one opening X3 side toward the other opening X3 side.

  The shape of the frame body X is not particularly limited as long as the filter medium 1 can be accommodated, for example, a rectangular parallelepiped shape having an inner dimension of 1180 mm × 1180 mm, an outer dimension of 1220 mm × 1220 mm, and a thickness of 75 mm, or a predetermined shape The circular thing etc. which have an internal diameter are mentioned. Further, the material of the frame body X is not particularly limited, and an aluminum material can be used.

  The filter medium 1 is adjusted so that the length L1 becomes a predetermined length, and is accommodated in the frame X. Specifically, the filter medium is more than the distance XL1 between the inner surfaces of the connecting wall X2 in the direction in which the filter medium 1 is accommodated in the frame body X (specifically, the direction along the length L1 direction of the filter medium 1). The length L1 of 1 is adjusted (cut) so as to be longer.

  The filter medium 1 is curved in the frame X while being accommodated in the frame X. Specifically, the filter medium 1 is accommodated in the frame body X, and both end portions in the length L1 direction are in contact with the inner surface of the frame body X (more specifically, the inner surface of the connecting wall X2). It will be in the state curved along the width L2 direction so that the area | region of the center side from the both ends of the length L1 direction may be located in the one opening X3 side rather than this both ends.

  In addition, the vertex parts of each bending part 1a (in other words, each bending part 1a formed in the side where the space | interval of each flat plate part 1b becomes wide) formed so that the one surface side of the filter medium 1 may become a peak side are mutually. The radius (curved radius) of the arc formed by connecting the two is not particularly limited, and is preferably, for example, 250 mm or more and 1500 mm or less, and more preferably 290 mm or more and 1200 mm or less.

  Between the filter medium 1 and the frame X, a caulking agent is filled. As the caulking agent, for example, a two-component epoxy caulking agent (specifically, a mixture of Macroplast 8104MC-18 manufactured by Henkel and Macroplast UK5400 in a ratio of 3: 1) can be used.

  Such a filter unit 10 is preferably used as a high efficiency particulate air (HEPA) filter such as a clean room, and an ultra low penetration air (ULPA) filter.

  The filter unit 10 configured as described above is arranged so that the length L1 direction of the filter medium 1 intersects (specifically, substantially orthogonal) with the flow direction F of the gas to be filtered. That is, the filter unit 10 is arranged so that the gas to be filtered contacts the filter medium 1 from the direction of the height L3 of the filter medium 1. Further, the filter unit 10 is arranged so that the region on the center side of both ends in the length L1 direction of the filter medium 1 is located on the upstream side in the flow direction F of the gas to be filtered from the both ends. Thus, the gas to be filtered that has flowed into the filter unit 10 from one opening X3 of the frame X passes through the filter medium 1 in the internal space XR and is discharged from the other opening X3 of the frame X. Configured.

  As described above, the filter medium and the filter unit according to the present invention can prevent unintentional deformation due to the wind pressure of the gas to be filtered.

  That is, the filter medium 1 is configured such that the thickness of the other surface side interval holding portion 3B is thinner than the thickness of the one surface side interval holding portion 3A, so that the other surface side of the filter material original fabric 2 is formed. The distance between the flat plate portions 1b is narrower than the distance between the flat plate portions 1b on one surface side of the filter medium raw fabric 2. For this reason, the region on the center side of both ends in the length direction of the filter medium 1 is more likely to bulge toward one surface side of the filter medium original fabric 2 than the both ends, and the filter medium 1 is easily curved. Thus, by using the filter medium 1 in a curved state, it is possible to suppress the filter medium 1 from being deformed by the wind pressure of the gas to be filtered.

  Specifically, when the filter medium 1 is curved as described above, the rigidity of the filter medium 1 is increased with respect to the wind pressure applied to the filter medium 1 from the side where the central region of the filter medium 1 swells. . For this reason, deformation of the filter medium 1 due to wind pressure can be suppressed.

  According to such a configuration, the thickness of the portion forming the other surface side interval holding portion 3B in the other surface side bead portion 3b is larger than the thickness of the portion forming the one surface side interval holding portion 3A in the one surface side bead portion 3a. By being configured to be thinner, it is formed so that the thickness of the other surface side interval holding portion 3B is thinner than the thickness of the one surface side interval holding portion 3A. As a result, the filter medium 1 can be easily bent and used as described above, and deformation of the filter medium 1 due to wind pressure can be suppressed.

  The filter medium and the filter unit according to the present invention are not limited to the above-described embodiment, and various modifications can be made without departing from the gist of the present invention. Further, the configurations and methods of the plurality of embodiments described above may be arbitrarily adopted and combined (even if the configurations and methods according to one embodiment are applied to the configurations and methods according to other embodiments). Of course, it is of course possible to arbitrarily select configurations, methods, and the like according to various modifications described below and employ them in the configurations, methods, and the like according to the above-described embodiments.

  For example, in the above embodiment, the bead portions 3a and 3b are formed so as to intersect with the bent portion 1a. However, the present invention is not limited to this, and as shown in FIG. Bead part 3a ', 3b' may be formed only from the part to form.

  Moreover, in the said embodiment, although the space | interval holding | maintenance part 3 is formed in multiple numbers at intervals along the bending part 1a, it is not limited to this, It forms integrally along the bending part 1a. Also good.

  Moreover, in the said embodiment, although the filter medium 1 is comprised using the filter medium raw fabric 2 which consists of the porous layer 2a and the base material layer 2b, it is not limited to this, For example, a porous layer You may use the filter-medium original fabric formed only from 2a. Moreover, in the said embodiment, although the filter-medium original fabric 2 is formed using the several porous layer 2a, it is not limited to this, From the single porous layer 2a and the base material layer 2b A filter medium original fabric may be formed.

  Examples of the present invention will be described below.

<Preparation of filter media>
1. Porous sheet A PTFE sheet was used as the porous sheet. Specifically, 20 parts by weight of a liquid lubricant (dodecane) was added to 100 parts by weight of PTFE fine powder (Fullon CD-123 manufactured by Asahi ICI Fluoropolymers) to obtain a paste-like mixture. Then, after the mixture was preformed into a rod shape, the preform was supplied between a pair of roller members and rolled as in the above embodiment to produce a long sheet (thickness: 200 μm). Thereafter, the long sheet is stretched 11 times along the longitudinal direction in an environment of 200 ° C., and is unfired by stretching 25 times along the width direction perpendicular to the longitudinal direction in an environment of 80 ° C. A PTFE sheet was obtained.
The obtained PTFE sheet was fired at 400 ° C. using a hot air generator. The PTFE sheet after firing had an average pore diameter of 0.6 μm, a thickness of 16 μm, an average fiber diameter of 0.08 μm, a collection efficiency of 99.999%, and a pressure loss of 160 Pa. The pressure loss and collection efficiency were determined by the following methods.

2. Breathable sheet Breathable sheet (Elves S030WDO manufactured by Unitika Co., Ltd.) formed so that one direction is the longitudinal direction was used.

3. Fabrication of the filter medium raw material A pair of roller members (the heat roller and the support roller) while laminating the porous sheet on both sides of the air permeable sheet so that the longitudinal directions of the porous sheet and the air permeable sheet are substantially parallel to each other ), And the porous sheet and the breathable sheet were heat-sealed and bonded together to prepare a filter medium original fabric 2 (width L2: 580 mm) as shown in FIG. The original filter medium 2 had a pressure loss of 170 Pa, a collection efficiency of 99.999%, and a thickness of 0.32 mm.

<Pressure loss>
Set the test sample (obtained porous sheet or filter medium original fabric 2) in an annular holder (effective area: 100 cm ² ), allow gas to pass through the test sample, and test the one side and the other side of the test sample. The pressure difference from the surface side was measured using a pressure gauge (manometer). In addition, the permeation | transmission flow rate was 5.3 cm / sec and it measured in eight places of a test sample. And the arithmetic mean of the obtained measurement result was made into pressure loss.

<Collection efficiency>
Set the test sample (the obtained porous sheet or filter medium raw fabric 2) in an annular holder (effective area: 100 cm ² ), and a gas containing about 10 ⁹ / L or more of polydispersed dioctyl phthalate (DOP). Permeated through the test sample. And the DOP density | concentration of the gas which permeate | transmitted the test sample was measured with the particle counter, and the collection efficiency (%) was computed using the following (1) Formula. The permeation flow rate was 5.3 cm / sec. The DOP particles were in the range of 0.1 to 0.2 μm.

Collection efficiency (%) = {1− (downstream concentration / upstream concentration)} × 100 (1)

<Examples 1 and 2>
= Filter media =
After the obtained filter medium 2 was pleated, as shown in FIG. 3, one side bead part 3a and the other side bead part 3b were formed to produce a filter medium 1. The obtained filter medium 1 had a length L1 of 580 mm, a width L2 of 580 mm, a height L3 of 35 mm, and 8 hooks per inch. As an adhesive (hot melt) for forming the bead portions 3a and 3b, Macromelt 6202 (polyamide type) manufactured by Henkel was used. In addition, it shows in following Table 1 about the ratio (bead front-back ratio) of the mass of the one surface side bead part 3a with respect to the mass of the other surface side bead part 3b. The bead front / back ratio was calculated using the following equation (2).

Bead front / back ratio = mass of one-side bead portion 3a / mass of other-side bead portion 3b (2)

In addition, the mass of the one surface side bead part 3a and the other surface side bead part 3b was measured as follows. Specifically, first, a test piece (1.0 m ² ) was collected from the filter medium 1 and its mass was measured. And the mass of the test piece when the test piece was heated and the one side bead part 3a (or the other side bead part 3b) was removed was measured. And the mass of one side bead part 3a (or other side bead part 3b) was computed from the mass difference before and behind heating of a test piece.

= Filter unit =
The filter medium 1 is housed inside the frame body X (inner dimensions are 580 mm x 580 mm, outer dimensions are 610 mm x 610 mm, and the thickness is 80 mm), and the frame X and filter medium are made using a two-pack epoxy caulking material. The filter unit 10 as shown in FIG. In addition, what mixed Henkel macroplast 8104MC-18 and macroplast UK5400 by the ratio of 3: 1 was used for 2 liquid epoxy caulking material.

  The filter medium 1 accommodated in the frame body X is in a curved state such that a region on the center side with respect to both ends in the length L1 direction is located on the one opening X3 side with respect to the both ends. In addition, the radius (curvature radius) of the circular arc formed by connecting the apexes of the respective bent portions 1a formed so that one surface side of the filter medium 1 becomes the mountain side is shown in Table 1 below.

= Pressure resistance test =
A load is applied to the central part of the filter medium 1 in the obtained filter unit from the side bulging from both ends in the length L1 direction, and the displacement amount of the central part of the filter medium 1 (displacement quantity in the load direction) Was measured. As a method of applying a load, a method of placing one or more weights (φ137 mm, 10 kg) in the center of the filter medium 1 was used.

<Comparative Example 1>
The deformation amount was measured under the same conditions as in Example 1 except that the bead front / back ratio was set to 0 and the filter medium 1 was accommodated in the frame body X without being bent. The amount of deformation is shown in Table 1 below.

<Summary>
When each example is compared with comparative example 1, it is recognized that each example has a smaller amount of deformation with respect to the load. That is, since the filter medium 1 is in a curved state as in each embodiment, the rigidity of the filter medium 1 is improved with respect to the load from the side where the center side of the filter medium 1 bulges. It can be seen that the deformation of 1 is suppressed.

  Moreover, when Example 1 and Example 2 are compared, it will be recognized that the bend radius decreases as the bead front / back ratio increases. That is, when the bead front / back ratio increases, the difference between the distance between the flat plate portions 1b on one side of the filter medium original fabric 2 and the distance between the flat plate portions 1b on the other surface side of the filter medium original fabric 2 increases. Therefore, the filter medium 1 can be bent more easily, and the bending radius can be reduced. Thereby, since the rigidity of the filter medium 1 as described above can be improved, it is recognized that the deformation of the filter medium 1 is more effectively suppressed.

  DESCRIPTION OF SYMBOLS 1 ... Filter medium, 1a ... Bending part, 1b ... Flat plate part, 2 ... Filter medium original fabric, 2a ... Porous layer, 2b ... Base material layer, 3A ... One surface side space | interval holding | maintenance part, 3B ... Other surface side space | interval holding | maintenance part DESCRIPTION OF SYMBOLS 3a ... One surface side bead part, 3b ... Other surface side bead part, 10 ... Filter unit, A1 ... Plane bending area, A2 ... Flat plate part planned area, X ... Frame body, X1 ... Opposite wall, X2 ... Connection wall, X3 ... opening, XR ... internal space, F ... distribution direction

Claims (4)

A plurality of bent portions formed by bending a filter medium original fabric capable of collecting particles contained in the gas to be filtered in a bowl shape and an area other than the bent portions in the filter medium original fabric are arranged so as to face each other. Filter medium comprising a plurality of flat plate portions and a plurality of gap holding portions formed between the flat plate portions on one surface side and the other surface side of the filter medium original fabric to hold the intervals between adjacent bent portions. Because
The gap holding part is formed by applying an adhesive to one surface of the filter medium original fabric and the other surface side bead formed by applying an adhesive to the other surface of the filter medium original fabric. Each part is formed by joining between flat plate parts,
The one surface side bead portion and the other surface side bead portion are formed on the surface on the mountain side of the bent portion in the filter medium original fabric,
The filter medium original fabric is configured such that the thickness of the portion forming the interval holding portion in the other surface side bead portion is thinner than the thickness of the portion forming the interval holding portion in the one surface side bead portion. Of the interval holding portions formed on both sides of the filter medium, the other surface side interval formed on the other surface side of the filter medium original fabric rather than the thickness of the one surface side interval holding portion formed on one surface side of the filter media original fabric It is configured so that the thickness of the holding part is thinner ,
A filter medium characterized by being curved so that the radius of curvature is 290 mm or more and 1200 mm or less . 2. The filter medium according to claim 1, wherein a ratio of a mass of the one-side bead portion to a mass of the other-side bead portion is 1.2 or more and 2.1 or less . Claim 1 or, wherein the 80% or less than 20% of the thickness of the portion where the thickness of the part forming the space holding portion to form a space holding portion in the other side bead portion of the one side bead portion 2. The filter medium according to 2. A filter unit in which the filter medium is accommodated in a frame that accommodates the filter medium according to any one of claims 1 to 3,
The frame body includes an opening for allowing the gas to be filtered to flow inside, and the filter medium is curved so that a region on the center side of both ends in the length direction is located on the opening side. A filter unit housed in a frame.

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