Chemical filter

Abstract

To provide a chemical filter having a long service life.SOLUTION: A chemical filter includes: a filter material which has absorption action or decomposition action and is folded into a pleat shape such that crest portions and trough portions are formed; and a filter frame which is configured to accommodate the filter material and has open surfaces formed on an upstream side and a downstream side in a gas flow direction. The filter material is arranged in the filter frame so that a direction in which the crest portions and the trough portions extend is a direction along the gas flow direction. The filter frame has a high-speed region where gas flowing speed is high and a low-speed region where gas flowing speed is lower than in the high-speed region. A porosity of the filter material in the high-speed region is smaller than that of the filter material in the low-speed region.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a chemical filter that adsorbs or decomposes a predetermined component contained in a gas. [Background technology]

[0002] Patent Document 1 discloses an example of a chemical filter. This chemical filter is arranged, for example, in an outside air treatment system of a clean room. The chemical filter includes a pleated filter medium and a filter frame that houses the filter medium. The filter medium is arranged in the filter frame such that the extension direction of the peaks and valleys is aligned with the gas flow direction. (See, for example, FIG. 10 of Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 10-165730 Summary of the Invention [Problem to be solved by the invention]

[0004] When the above-mentioned chemical filter using activated carbon as an adsorbent adsorbs multiple components contained in gas, both low-boiling point substances and high-boiling point substances are adsorbed in the initial stage of adsorption, so the removal rate is maintained at a high level. However, as time passes, a substitution adsorption phenomenon occurs, and the adsorbed low-boiling point substances are replaced by high-boiling point substances and desorbed. In the final stage of adsorption, the high-boiling point substances reach an adsorption equilibrium state, so the removal rate of the low-boiling point substances contained in the gas decreases.

[0005] For example, in a semiconductor manufacturing process, gases containing low-boiling-point substances originating from the outside air and wafer cleaning liquids, etc., have a detrimental effect on the exposure process, so it is required to preferably remove the low-boiling-point substances contained in the gas for as long a period as possible. In addition, even in a chemical filter that decomposes a specific component contained in the gas using a catalyst, it is preferable to suppress the decrease in catalyst activity as much as possible, in other words, to have a long life.

[0006] An object of the present invention is to provide a chemical filter having a long life. [Means for solving the problem]

[0007] A chemical filter according to a first aspect of the present invention comprises a filter material having an adsorption or decomposition action and folded into pleats so as to form peaks and valleys, and a filter frame configured to be able to accommodate the filter material and having openings formed on the upstream and downstream sides in a gas flow direction, the filter material is arranged within the filter frame such that the extension direction of the peaks and valleys is along the gas flow direction, the filter frame has a high speed region where the gas flows at a high speed and a low speed region where the gas flows at a slower speed than the high speed region, and the porosity of the filter material in the high speed region is smaller than the porosity of the filter material in the low speed region.

[0008] The inventor of the present application found that within the filter frame of a chemical filter, there exists a high-speed region where the gas flows at a high speed and a low-speed region where the gas flows at a slower speed than the high-speed region. For example, when the porosity of the filter medium in the high-speed region is the same as the porosity of the filter medium in the low-speed region, the adsorbent of the filter medium in the high-speed region is consumed faster than that in the low-speed region. Also, the catalyst activity of the filter medium decreases more quickly in the high-speed region than in the low-speed region. Therefore, the adsorption or decomposition action of the filter medium in the high-speed region decreases more quickly.

[0009] According to the chemical filter of the first aspect, the porosity of the filter medium in the high-velocity region is smaller than the porosity of the filter medium in the low-velocity region, so that the gas flows suitably even in the low-velocity region. For example, in the case of a chemical filter including a filter medium having an adsorption function, the consumption of the adsorbent in the high-velocity region is suppressed, so that the bias of the consumption of the adsorbent in the entire filter medium is suppressed. As a result of the reduction in the adsorption of high-boiling point components to the filter medium in the high-velocity region, the replacement adsorption phenomenon of the filter medium in the high-velocity region is alleviated. Since the desorption of the adsorbed low-boiling point substances is suppressed, the life of the chemical filter is long. In addition, in the case of a chemical filter including a filter medium having a decomposition function, the decrease in the activity of the catalyst in the high-velocity region is suppressed, so that the bias of the decrease in the activity of the catalyst in the entire filter medium is suppressed. Therefore, the life of the chemical filter is long.

[0010] A chemical filter according to a second aspect of the present invention is the chemical filter according to the first aspect, wherein the porosity of the filter medium in the high velocity region is in the range of 65% or more and 90% or less of the porosity of the filter medium in the low velocity region.

[0011] According to the chemical filter of the second aspect, the porosity of the filter medium in the high velocity region falls within the above range, and therefore the service life is longer.

[0012] A chemical filter according to a third aspect of the present invention is the chemical filter according to the first or second aspect, wherein the filter medium contains an adsorbent.

[0013] The chemical filter according to the third aspect can suitably adsorb a predetermined component contained in a gas.

[0014] A chemical filter according to a fourth aspect of the present invention is the chemical filter according to the third aspect, further comprising an agent attached to the adsorbent so as to adsorb at least one of acidic components, base components, ozone, and hydrogen peroxide contained in the gas.

[0015] The chemical filter according to the fourth aspect can suitably adsorb acidic components, basic components, ozone, and hydrogen peroxide.

[0016] A chemical filter according to a fifth aspect of the present invention is the chemical filter according to the third or fourth aspect, wherein the adsorbent is activated carbon, an ion exchange resin, a molecular sieve, activated alumina, silica gel, a zeolite, or a metal-organic framework.

[0017] A chemical filter according to a sixth aspect of the present invention is the chemical filter according to any one of the first to fifth aspects, wherein the filter medium includes a first filter medium and a second filter medium.

[0018] A chemical filter according to a seventh aspect of the present invention is the chemical filter according to the sixth aspect, further comprising a partition material disposed between the first filter medium and the second filter medium.

[0019] According to the chemical filter of the seventh aspect, the valley portions of one of the first filter medium and the second filter medium are prevented from entering between the peak portions of the other filter medium.

[0020] A chemical filter according to an eighth aspect of the present invention is the chemical filter according to the seventh aspect, wherein the material constituting the partition material is the same as the material constituting the filter medium.

[0021] According to the chemical filter of the eighth aspect, a predetermined component contained in a gas can be adsorbed or decomposed by the partition material.

[0022] A chemical filter according to a ninth aspect of the present invention is the chemical filter according to any one of the first to eighth aspects, wherein the filter medium and the filter frame are partially joined together.

[0023] According to the chemical filter of the ninth aspect, the position of the filter medium within the filter frame is stabilized. Effect of the Invention

[0024] The chemical filter of the present invention can achieve a long service life. [Brief description of the drawings]

[0025] [Figure 1] FIG. 2 is a front view of the chemical filter according to the embodiment. [Diagram 2] Rear view of the chemical filter in Figure 1. [Diagram 3] FIG. 2 is a side view of the chemical filter of FIG. 1. [Figure 4] FIG. 2 is a front view of a filter medium provided in the chemical filter of FIG. 1. [Diagram 5] FIG. 5 is a cross-sectional view showing an example of a layer structure of the filter medium in FIG. [Figure 6] FIG. 2 is a front view of the filter frame of FIG. 1 . [Figure 7] FIG. 4 is a cross-sectional view showing an example of a layer structure of a filter medium included in a chemical filter of a first modified example. [Figure 8] FIG. 11 is a cross-sectional view showing an example of a layer structure of a filter medium included in another example of the chemical filter according to the first modified example. [Figure 9] FIG. 13 is a front view of a chemical filter according to a second modified example. [Figure 10] 4 is a table showing specifications of chemical filters of examples and comparative examples. [Figure 11] 1 is a table showing test results of the chemical filters of Examples and Comparative Examples. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0026] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A chemical filter according to an embodiment of the present invention will now be described with reference to the drawings.

[0027] [Embodiment] <1. Chemical filter configuration> Fig. 1 is a front view of a chemical filter 10 (hereinafter referred to as "filter 10") of this embodiment. Fig. 2 is a rear view of filter 10. Fig. 3 is a side view of filter 10. Hereinafter, the up-down direction of filter 10 in Fig. 1 or Fig. 2 will be referred to as the height direction, and the direction perpendicular to the height direction in a front or rear view of filter 10 will be referred to as the width direction.

[0028] The filter 10 is disposed, for example, in an outside air processing system of a clean room, a circulating air conditioning system of a clean room, a duct connected to a clean booth for semiconductor manufacturing equipment, or in the semiconductor manufacturing equipment. The filter 10 is configured to reduce the load in the early stage of adsorption by allowing a portion of a gas (hereinafter referred to as "gas") containing the components to be adsorbed to pass through to some extent in the early stage of adsorption. The gas includes a high boiling point substance and a low boiling point substance. The filter 10 includes a filter frame 20, a filter medium 30, and a partition material 40.

[0029] The filter frame 20 houses the filter medium 30 and the partition material 40. The outer shape of the filter frame 20 can be selected arbitrarily. In this embodiment, the outer shape of the filter frame 20 is a rectangular parallelepiped extending in the gas flow direction XA. The outer shape of the filter frame 20 may be a cube. The material constituting the filter frame 20 can be selected arbitrarily. The material constituting the filter frame 20 is, for example, a stainless steel plate, an iron plate, an aluminum plate, or a resin.

[0030] The filter frame 20 has an upper plate 21, a lower plate 22, and a pair of side plates 23 connecting the upper plate 21 and the lower plate 22. The filter frame 20 may be formed such that the upper plate 21, the lower plate 22, and the pair of side plates 23 are integrally formed, or may be formed separately and joined together. The filter medium 30 and the partition material 40 are accommodated in a space 20A surrounded by the upper plate 21, the lower plate 22, and the pair of side plates 23.

[0031] The filter frame 20 has openings 20X and 20Y formed at the ends in the longitudinal direction. The opening 20X constitutes a gas inlet. The opening 20Y constitutes a gas outlet. The gas that has entered the space 20A of the filter frame 20 from the opening 20X has its components to be adsorbed by the filter medium 30. The gas from which the components to be adsorbed have been adsorbed by the filter medium 30 passes through the opening 20Y and flows into a clean room or the like.

[0032] In this embodiment, the filter medium 30 has an adsorption effect. The filter medium 30 is accommodated in the filter frame 20 in a pleated state. The number of filter media 30 accommodated in one filter frame 20 can be selected arbitrarily. In this embodiment, three filter media 30 are accommodated in one filter frame 20. One, two, or four or more filter media 30 may be accommodated in one filter frame 20.

[0033] The three filter media 30 are arranged side by side in the height direction of the filter frame 20. Hereinafter, the filter media 30 arranged at the top in the height direction of the filter frame 20 will be referred to as the first filter media 50, the filter media 30 adjacent to the first filter media 50 will be referred to as the second filter media 60, and the filter media arranged at the bottom will be referred to as the third filter media 70. When there is no particular distinction between the first filter media 50, the second filter media 60, and the third filter media 70, they will be simply referred to as the filter media 30. Note that when the filter 10 includes multiple filter media 30, the multiple filter media 30 may be placed flat so that gas flows in the vertical direction.

[0034] The filter medium 30 has a plurality of peaks 30X and a plurality of valleys 30Y. The filter medium 30 is disposed in the filter frame 20 such that the extension direction of the peaks 30X and the valleys 30Y is the gas flow direction XA. Therefore, the cross-sectional shape of the filter medium 30 appears at the opening faces 20X and 20Y of the filter frame 20. Hereinafter, a portion of the filter medium 30 that is bent to form one peak 30X and a portion that is bent to form one valley 30Y may be referred to as a unit pleat.

[0035] The curvature radius R of the peaks 30X and valleys 30Y can be selected arbitrarily. From the viewpoint of reducing the pressure loss of the gas and from the viewpoint of favorably adsorbing the components to be adsorbed contained in the gas, it is preferable that the curvature radius R is in the range of 0.7 to 4.0. When the curvature radius R is 0.7 or more, a certain area is secured in the gaps of the unit pleats, so that the increase in the pressure loss of the filter 10 can be suppressed. When the curvature radius R is 4.0 or less, the area of ​​the gaps of the unit pleats is narrowed, but the peaks 30X and valleys 30Y can be formed in large numbers. In addition, when the curvature radius R is 4.0 or less, the length in the width direction of the filter medium 30 before being folded into pleats (hereinafter, referred to as the "length of the filter medium 30 before pleat formation") can be made long. When the curvature radius R is 4.0 or less, the surface area of ​​the filter medium 30 is large, so that the components to be adsorbed contained in the gas can be favorably adsorbed. The radii of curvature R of the peaks 30X and the radii of curvature R of the valleys 30Y may be the same or at least some of them may be different.

[0036] FIG. 4 is a front view of the filter medium 30. In the width direction of the filter 10, the interval LA between the adjacent ridges 30X can be selected arbitrarily. From the viewpoint of reducing the pressure loss of the gas and from the viewpoint of favorably adsorbing the components to be adsorbed contained in the gas, the interval LA is preferably in the range of 1 mm to 5 mm, and more preferably in the range of 1 mm to 2 mm. When the interval LA is 1 mm or more, the interval between the adjacent ridges 30X is sufficiently wide, so that the increase in the pressure loss of the filter 10 can be suppressed. When the interval LA is 5 mm or less, the interval between the adjacent ridges 30X is narrow, but the ridges 30X and the valleys 30Y can be formed in large numbers. Therefore, the length of the filter medium 30 before pleating can be increased. When the interval LA is 5 mm or less, the surface area of ​​the filter medium 30 is large, so that the components to be adsorbed contained in the gas can be favorably adsorbed. The interval LA is the interval between the opposing roots of the adjacent ridges 30X in the width direction. The intervals LA may be the same for all of the peaks 30X, or may be different for at least some of them.

[0037] The height LB of the unit pleat of the filter medium 30 can be selected arbitrarily. The height LB is determined based on the number of peaks 30X and the number of valleys 30Y to be formed. The height LB of the unit pleat of the filter medium 30 may be constant or may vary partially. When the height LB of the unit pleat of the filter medium 30 varies partially, the average value of the height LB of the unit pleat may be set as the height LB of the unit pleat. When the filter medium 30 before being folded into pleats is in a roll shape, it is preferable to determine the length before pleat formation based on the height LB of the unit pleat, the number of peaks 30X, and the number of valleys 30Y.

[0038] FIG. 5 is a cross-sectional view showing an example of the layer structure of the filter medium 30. The thickness of the filter medium 30 is preferably in the range of 0.5 mm to 2.5 mm in terms of strength, formability of pleats, and the amount of adsorbent and binder. When the thickness of the filter medium 30 is 0.5 mm or more, the strength of the filter medium 30 is high and it is difficult to break. When the thickness of the filter medium 30 is 2.5 mm or less, many peaks 30X and valleys 30Y of the filter medium 30 can be formed. The filter medium 30 includes a pair of nonwoven fabrics 31, 32 and an adsorption layer 33 sandwiched between the pair of nonwoven fabrics 31, 32.

[0039] The material constituting the pair of nonwoven fabrics 31, 32 can be selected arbitrarily as long as it is a material capable of holding the adsorption layer 33. The material constituting the pair of nonwoven fabrics 31, 32 is, for example, a polyester-based nonwoven fabric.

[0040] The adsorption layer 33 is a layer in which an adsorbent 33A and a binder 33B are mixed in a predetermined ratio. A material capable of adsorbing at least an organic substance is selected as the adsorbent 33A. The organic substance includes at least one of alcohol, halogenated hydrocarbon, hydrocarbon, fatty acid, fatty acid ester, silanol, siloxane, and organic phosphorus compound, for example.

[0041] The adsorbent 33A is, for example, activated carbon, ion exchange resin, molecular sieve (synthetic zeolite, carbon molecular sieve, etc.), activated alumina, silica gel, zeolite, or metal organic structure. In this embodiment, granular activated carbon (coconut shell) is used as the adsorbent 33A so as to suitably adsorb isopropyl alcohol as a low boiling point substance. Instead of the adsorbent 33A, a catalyst that decomposes the components to be decomposed contained in the gas may be disposed. That is, the filter medium 30 may have a decomposition function.

[0042] The adsorbent 33A is preferably impregnated with a chemical agent so as to adsorb at least one of an acidic component, a basic component, ozone, and hydrogen peroxide. The acidic component is, for example, hydrogen sulfide, SOx, NOx, hydrogen chloride, hydrogen fluoride, acetic acid, formic acid, nitric acid, or sulfuric acid. The basic component is ammonia or an amine-based substance. The chemical agent is, for example, potassium carbonate or phosphoric acid.

[0043] The binder 33B bonds the pair of nonwoven fabrics 31, 32 and the adsorbent 33A. The binder 33B is, for example, additive-free polyethylene. A mixture of the adsorbent 33A and the binder 33B in a predetermined ratio is applied, for example, to the surface of the nonwoven fabric 31. The nonwoven fabric 32 is placed on the nonwoven fabric 31 to which the mixture has been applied, and the pair of nonwoven fabrics 31, 32 and the mixture are hot-pressed with a roll to a desired thickness. The filter medium 30 is completed by hardening the binder 33B.

[0044] The first filter medium 50 preferably has side surfaces of unit pleats at both ends in the width direction and at least some of the apexes of the multiple ridges 30X bonded to the filter frame 20 with an adhesive 80 (see FIG. 1). The adhesive 80 is, for example, a low outgassing urethane adhesive. In this embodiment, the side surfaces of unit pleats at both ends in the width direction of the first filter medium 50 are bonded to the inner surfaces of the pair of side plates 23 with the adhesive 80. The apexes of all of the ridges 30X of the first filter medium 50 are bonded to the inner surface of the upper plate 21 with the adhesive 80.

[0045] It is preferable that at least a portion of the side surfaces of the unit pleats at both ends in the width direction of the second filter medium 60 are joined to the filter frame 20 with an adhesive 80. In this embodiment, the side surfaces of the unit pleats at both ends in the width direction of the second filter medium 60 are joined to the inner surfaces of the pair of side plates 23 with the adhesive 80.

[0046] It is preferable that the side surfaces of the unit pleats at both ends in the width direction of the third filter medium 70 and at least some of the apexes of the multiple valley portions 30Y are joined to the filter frame 20 with an adhesive 80 (see FIG. 1). In this embodiment, the side surfaces of the unit pleats at both ends in the width direction of the third filter medium 70 are joined to the inner surfaces of the pair of side plates 23 with the adhesive 80. The apexes of all of the valley portions 30Y of the second filter medium 60 are joined to the inner surface of the lower plate 22 with the adhesive 80.

[0047] The partition material 40 is disposed in the filter frame 20, for example, between the first filter medium 50 and the second filter medium 60 and between the second filter medium 60 and the third filter medium 70. The apexes of the valleys 30Y of the first filter medium 50, the apexes of the peaks 30X and the valleys 30Y of the second filter medium 60, and the apexes of the peaks 30X of the third filter medium 70 are in contact with the partition material 40.

[0048] Any material can be selected for the partitioning material 40. From the viewpoint of suitably adsorbing the components to be adsorbed contained in the gas, the material for the partitioning material 40 is preferably the same as the material for the filter medium 30. The material for the partitioning material 40 may be a lath net or a metal plate.

[0049] 6 is a front view of the filter frame 20 in a state where the filter medium 30 and the partition material 40 are not arranged. In FIG. 6, the position where the filter medium 30 can be arranged is indicated by a two-dot chain line in order to easily grasp the position of the filter medium 30. The inventors of the present application found that the filter frame 20 has a high-speed region RA where the gas flows at a high speed and a low-speed region RB where the gas flows at a slower speed than the high-speed region RA. In this embodiment, in order to suppress the desorption of the adsorbed low-boiling point substance, the filter 10 is configured so that the porosity of the filter medium 30 in the high-speed region RA is smaller than the porosity of the filter medium 30 in the low-speed region RB.

[0050] In the filter frame 20, the positions where the high-speed region RA and the low-speed region RB exist vary depending on the environment in which the filter 10 is installed. In a typical example, in a front view or a back view of the filter frame 20, the high-speed region RA exists in a portion including approximately the center of the filter frame 20. The low-speed region RB exists around the high-speed region RA. In this embodiment, the second filter medium 60 is arranged so as to mainly include the high-speed region RA. The second filter medium 60 is arranged so as to mainly include the high-speed region RA, for example, when the second filter medium 60 is arranged so as to include 50% or more of the high-speed region RA. The first filter medium 50 and the third filter medium 70 are arranged so as to mainly include the low-speed region RB. The first filter medium 50 and the third filter medium 70 are arranged so as to mainly include the low-speed region RB, for example, when the first filter medium 50 and the third filter medium 70 are arranged so as to include 50% or more of the low-speed region RB. The filter 10 is configured such that the porosity of the second filter medium 60 arranged mainly in the high-speed region RA is smaller than the porosity of the first filter medium 50 and the second filter medium 70 arranged in the low-speed region RB. In this embodiment, the porosity of the first filter medium 50, the second filter medium 60, and the third filter medium 70 is generally constant. The porosity of the first filter medium 50, the second filter medium 60, and the third filter medium 70 may be partially different. When the porosity of the first filter medium 50, the second filter medium 60, and the third filter medium 70 is partially different, the porosity of the first filter medium 50, the second filter medium 60, and the third filter medium 70 is the average value of the respective porosities.

[0051] In this embodiment, the porosity is defined by the following formula (1). Porosity (%) = (1 - {thickness of filter medium 30 (mm) × number of ridges 30X × 2 / inner dimension of filter frame 20 in the width direction (mm)}) × 100 (1)

[0052] From the viewpoint of suitably suppressing the desorption of the adsorbed low boiling point substance, the porosity of the second filter medium 60 arranged mainly including the high speed region RA is preferably in the range of 65% to 90% of the porosity of at least one of the first filter medium 50 and the third filter medium 70 arranged mainly including the low speed region RB. In this embodiment, the porosity of the second filter medium 60 is in the range of 65% to 90% of the porosity of each of the first filter medium 50 and the third filter medium 70. When the porosity of the second filter medium 60 is 65% or more of the porosity of at least one of the first filter medium 50 and the third filter medium 70, the pressure loss of the filter 10 can be suppressed from increasing. When the porosity of the second filter medium 60 is 90% or less of the porosity of at least one of the first filter medium 50 and the third filter medium 70, the rate of decrease in the adsorption action of the second filter medium 60 becomes gentle.

[0053] When the height LB of the unit pleats of the first filter medium 50, the second filter medium 60, and the third filter medium 70 is the same, the longer the length before pleating, the more the number of peaks 30X and valleys 30Y that can be formed, and therefore the smaller the porosity of the filter medium 30. In other words, when the height LB of the unit pleats of the first filter medium 50, the second filter medium 60, and the third filter medium 70 is the same, the shorter the length before pleating, the fewer the number of peaks 30X and valleys 30Y, and therefore the larger the porosity of the filter medium 30.

[0054] In this embodiment, the pre-pleat length of the second filter medium 60 is longer than the pre-pleat length of the first filter medium 50 and the pre-pleat length of the third filter medium 70. In this embodiment, the pre-pleat length of the first filter medium 50 and the pre-pleat length of the third filter medium 70 are equal. In this embodiment, the heights LB of the unit pleats of the first filter medium 50, the second filter medium 60, and the third filter medium 70 are the same. Therefore, the number of peaks 30X and valleys 30Y of the second filter medium 60 is greater than the number of peaks 30X and valleys 30Y of the first filter medium 50 and the number of peaks 30X and valleys 30Y of the third filter medium 70.

[0055] <2. Function of chemical filters> Gas that has entered the space 20A of the filter frame 20 from the opening surface 20X passes through the unit pleats that make up the peaks 30X and the unit pleats that make up the valleys 30Y. Due to the pleat shape of the filter medium 30, a very small portion of the gas components to be adsorbed pass through the filter 10 without being adsorbed by the filter medium 30. The adsorption of high boiling point components to the filter medium 30 is reduced, and the substitution adsorption phenomenon is alleviated, so that the desorption of the adsorbed low boiling point substances is suppressed. The gas to which the components to be adsorbed have been adsorbed by the filter medium 30 passes through the opening surface 20Y and flows into a clean room or the like.

[0056] <3. Effects of chemical filters> <3-1> According to the chemical filter 10, the porosity of the second filter medium 60 in the high-speed region RA is smaller than the porosity of the first filter medium 50 and the third filter medium 70 in the low-speed region RB, so that the gas flows suitably even in the low-speed region RB. When the chemical filter 10 includes the filter medium 30 having an adsorption function, the consumption of the adsorbent 33A in the high-speed region RA is suppressed, so that the bias of the consumption of the adsorbent 33A in the filter medium 30 as a whole is suppressed. As a result of the reduction in the adsorption of the high-boiling point component to the second filter medium 60 in the high-speed region RA, the substitution adsorption phenomenon is alleviated, and the desorption of the adsorbed low-boiling point substance is suppressed. Therefore, the life of the chemical filter 10 is long.

[0057] <3-2> The filter medium 30 has the adsorbent 33A impregnated with a chemical, and therefore can suitably adsorb acidic components, basic components, ozone, and hydrogen peroxide.

[0058] <3-3> Since the filter 10 includes the partition material 40, the valley portions 30Y of the first filter medium 50 are prevented from entering between adjacent peak portions 30X of the second filter medium 60.

[0059] <3-4> When the material constituting the partitioning material 40 is the same as the material constituting the filter medium 30, the partitioning material 40 can also adsorb low boiling point substances contained in the gas.

[0060] <3-5> Since the filter medium 30 and the filter frame 20 are partially joined by the adhesive 80, the position of the filter medium 30 within the filter frame 20 is stable.

[0061] <3-6> Since the gaps between the unit pleats of the filter medium 30 face the opening faces 20X and 20Y of the filter frame 20, gas that has entered the filter frame 20 from the opening faces 20X can easily pass through the pleats. This reduces the pressure loss of the filter 10. The filter 10 can be suitably applied to a fan filter unit.

[0062] <3-7> In a mat-type filter, which is another conventional low-pressure-loss chemical filter, in other words a filter that uses a foam as a base material and has an adsorbent such as activated carbon beads attached thereto, it is difficult to increase the amount of adsorbent. In the filter 10 of the present embodiment, the adsorbent 33A is sandwiched between a pair of nonwoven fabrics 31 and 32, so that the amount of adsorbent 33A can be designed to be large.

[0063] <3-8> Filter 10 can be formed by folding filter media 30 into pleats, and is therefore easier to manufacture than other conventional honeycomb-type filters.

[0064] <3-9> In the filter medium 30, the adsorbent 33A is sandwiched between the pair of nonwoven fabrics 31 and 32, so that the adsorbent 33A is prevented from being desorbed. Therefore, the dust generation is low.

[0065] <3-10> The filter medium 30 may deform so that the intervals LA between adjacent ridges 30X become non-uniform, narrowing the gaps between the unit pleats. In the filter medium 30 of the filter 10 of this embodiment, the gaps between the unit pleats face the opening faces 20X and 20Y of the filter frame 20. For this reason, even if the filter medium 30 is deformed, the narrowed gaps between the unit pleats can be easily widened by, for example, inserting a comb-shaped member into the gaps between the unit pleats.

[0066] [4. Modifications] The above-mentioned embodiment is an example of a form that the chemical filter according to the present invention can take, and is not intended to limit the form. The chemical filter according to the present invention can take a form different from the form exemplified in the embodiment. One example is a form in which a part of the configuration of the embodiment is replaced, changed, or omitted, or a form in which a new configuration is added to the embodiment. Some examples of modified embodiments are shown below. Note that the following modified embodiments can be combined with each other as long as they are not technically inconsistent.

[0067] <4-1. First modified example> In the above embodiment, the configuration of the filter medium 30 can be changed arbitrarily. As shown in FIG. 7, for example, the filter medium 30 may be composed of only the adsorbent 33A. In this modification, the adsorbent 33A is, for example, activated carbon fiber. In another example, the filter medium 30 may not have a layered structure, but may be a support sheet formed in a state in which powder such as activated carbon is entangled and integrated with a sheet during the papermaking process. In yet another example, as shown in FIG. 8, the filter medium 30 may be a support sheet in which a powdered adsorbent 33A or catalyst 33C is supported on a sheet 100. From the viewpoint of formability, it is preferable that the support sheet is laminated with a stiff sheet that serves as a bone.

[0068] <4-2. Second modified example> In the above embodiment, as shown in Fig. 9, the filter 10 may omit the third filter medium 70. In this modification, for example, a portion including the center of the first filter medium 50 and the second filter medium 60 in the width direction is included in the high speed region RA. A portion including the end of the first filter medium 50 and the second filter medium 60 in the width direction is included in the low speed region RB.

[0069] In the second modified example, the porosity in the high-velocity region RA of the first filter material 50 is defined by replacing the "thickness (mm) of the filter material 30" in the above formula (1) with the "thickness (mm) of the portion of the first filter material 50 included in the high-velocity region RA", replacing the "number of ridge portions 30X" with the "number of ridge portions 30X in the high-velocity region RA", and replacing the "inner width dimension (mm) of the filter frame 20" with the "inner width dimension (mm) of the filter frame 20 in the high-velocity region RA".

[0070] In the second modified example, the porosity in the low-speed region RB of the first filter material 50 is defined by replacing the "thickness (mm) of the filter material 30" in the above formula (1) with the "thickness (mm) of the portion of the first filter material 50 included in the low-speed region RB", replacing the "number of ridge portions 30X" with the "number of ridge portions 30X in the low-speed region RB", and replacing the "inner width dimension (mm) of the filter frame 20" with the "inner width dimension (mm) of the filter frame 20 in the low-speed region RB".

[0071] In the second modified example, the porosity in the high-velocity region RA of the second filter material 60 is defined by replacing the "thickness (mm) of the filter material 30" in the above formula (1) with the "thickness (mm) of the portion of the second filter material 60 included in the high-velocity region RA", replacing the "number of ridge portions 30X" with the "number of ridge portions 30X in the high-velocity region RA", and replacing the "inner width dimension (mm) of the filter frame 20" with the "inner width dimension (mm) of the filter frame 20 in the high-velocity region RA".

[0072] In the second modified example, the porosity in the low-speed region RB of the second filter material 60 is defined by replacing the "thickness (mm) of the filter material 30" in the above formula (1) with the "thickness (mm) of the portion of the second filter material 60 included in the low-speed region RB", replacing the "number of ridge portions 30X" with the "number of ridge portions 30X in the low-speed region RB", and replacing the "inner width dimension (mm) of the filter frame 20" with the "inner width dimension (mm) of the filter frame 20 in the low-speed region RB".

[0073] <4-3.Third modified example> In the above embodiment, the filter 10 may omit the second filter medium 60 and the third filter medium 70. In the third modified example, for example, a portion including the center of the first filter medium 50 in the width direction is included in the high speed region RA. A portion including the end of the first filter medium 50 in the width direction is included in the low speed region RB. In the third modified example, the definitions of the porosity of the first filter medium 50 in the high speed region RA and the porosity of the first filter medium 50 in the low speed region RB are the same as those in the second modified example.

[0074] <4-4. Fourth modified example> In the above embodiment, it is also possible to combine a plurality of filters 10. For example, a filter 10 having a first porosity may be arranged so as to mainly include a high-speed region RA, and a filter 10 having a second porosity higher than the first porosity may be arranged so as to mainly include a low-speed region RB.

[0075] <4-5. Fifth modified example> In the above embodiment, the filter material 30 and the filter frame 20 were partially joined by adhesive 80, but the filter material 30 and the filter frame 20 may also be partially joined by other joining means such as double-sided tape.

[0076] <4-6. Sixth Variation> In the above embodiment, the partition material 40 extends over substantially the entire length of the filter frame 20 in the longitudinal direction, but the length of the partition material 40 may be shorter than the length of the filter frame 20 in the longitudinal direction.

[0077] 5. Working Examples The inventor(s) of the present application manufactured chemical filters (hereinafter referred to as "filters") of Examples 1 and 2 and Comparative Examples 1, 2, and 3, and conducted tests to confirm the removal rate of low boiling point substances contained in gas. For the sake of convenience, the following description will be given by assigning the same reference numerals as in the embodiment to the elements constituting the filters of Examples 1 and 2 and Comparative Examples 1, 2, and 3 that are the same as in the embodiment.

[0078] The specifications of the filter medium 30 included in the filters of Examples 1 and 2 and Comparative Examples 1, 2, and 3 are as follows.

[0079] The material constituting the pair of nonwoven fabrics 31 and 32 is a polyester-based nonwoven fabric. The adsorbent 33A is granular activated carbon (coconut shell). The particle size of the granular activated carbon is in the range of 0.25 mm to 0.85 mm. The amount of the granular activated carbon enclosed is 600 g / m 2 The binder 33B is additive-free polyethylene. The weight ratio of the adsorbent 33A to the binder 33B in the adsorption layer 33 is 100 parts by weight of the adsorbent 33A and 18 parts by weight of the binder 33B. The overall thickness of the filter medium 30 is within the range of 1.9 mm to 2.1 mm.

[0080] Other specifications of the filters of Examples 1 and 2 and Comparative Examples 1, 2, and 3 are as shown in FIG. 10. The filters of Examples 1 and 2 are filters of the embodiment, and are configured so that the porosity of the second filter medium 60 is lower than the porosity of the first filter medium 50 and the porosity of the third filter medium 70. The filters of Comparative Examples 1 and 2 are configured so that the porosity of the first filter medium 50, the porosity of the second filter medium 60, and the porosity of the third filter medium 70 are the same. The filter of Comparative Example 3 is configured so that the porosity of the second filter medium 60 is higher than the porosity of the first filter medium 50 and the porosity of the third filter medium 70. The filters of Examples 1 and 2 and Comparative Examples 1, 2, and 3 do not have a partition material 40. The dimensions of the filter frames 20 in Examples 1 and 2 and Comparative Examples 1, 2, and 3 are 170 mm in height, 170 mm in width, and 270 mm in depth.

[0081] In the test, gas containing high boiling point substances and low boiling point substances was passed through the filters of Examples 1 and 2 and Comparative Examples 1, 2, and 3, and the removal rate of the low boiling point substances was calculated. The high boiling point substances were hexane and benzene. The low boiling point substance was isopropyl alcohol. The gas contained hexane, benzene, and isopropyl alcohol as well as any other volatile organic compounds.

[0082] The removal rate RX (%) is calculated based on the upstream average concentration CA and the downstream average concentration CB by the following formula (2). RA(%)={(CA-CB) / CA}×100···(2)

[0083] The upstream average concentration CA is the concentration of high boiling point substances or low boiling point substances contained in the gas before passing through the filters of Examples 1 and 2 and the filters of Comparative Examples 1, 2, and 3. The downstream average concentration CB is the concentration of high boiling point substances or low boiling point substances contained in the gas after passing through the filters of Examples 1 and 2 and the filters of Comparative Examples 1, 2, and 3.

[0084] The average upstream concentration CA of isopropyl alcohol in the filters of Examples 1 and 2 and Comparative Examples 1, 2, and 3 was 50 to 75 μg / m 3 The average upstream concentration of hexane, CA, is in the range of 75 to 140 μg / m 3 The average upstream concentration of benzene, CA, is in the range of 25 to 50 μg / m 3 is included in the range.

[0085] FIG. 11 shows the test results. As shown in FIG. 11, it was confirmed that the filters of Examples 1 and 2 had a high removal rate of isopropyl alcohol of 60% or more until about the 8th day. It was confirmed that the filters of Comparative Examples 1 and 2 had a removal rate of isopropyl alcohol of less than 60% from about the 4th day. It was confirmed that the filter of Comparative Example 3 had a removal rate of isopropyl alcohol of less than 60% from about the 2nd day. This is because the filters of Examples 1 and 2 reduced the adsorption of high boiling point components to the second filter medium 60 in the high speed region RA, which resulted in the substitution adsorption phenomenon being alleviated and the desorption of the adsorbed low boiling point substances being suppressed. For this reason, it was confirmed that the filters of Examples 1 and 2 had a longer life than the filters of Comparative Examples 1, 2, and 3. [Explanation of symbols]

[0086] 10: Chemical filter 20: Filter frame 20X: Opening surface 20Y: Opening surface 30: Filter media 30X: Mountain 30Y: Tanibe 33A: Adsorbent 40: Partition material 50: First filter material 60: Second filter media

Claims

1. A filter medium having an adsorption or decomposition function and folded in a pleated shape so as to form peaks and valleys; a filter frame configured to be able to accommodate the filter medium and having openings formed on the upstream side and the downstream side in the gas flow direction; The filter medium is disposed within the filter frame such that the extension direction of the peaks and the valleys is aligned with the gas flow direction, the filter frame has a high-velocity region in which the gas flows at a high velocity and a low-velocity region in which the gas flows at a slower velocity than the high-velocity region, The porosity of the filter medium in the high velocity region is smaller than the porosity of the filter medium in the low velocity region. Chemical filters.

2. The porosity of the filter medium in the high-velocity region is in the range of 65% to 90% of the porosity of the filter medium in the low-velocity region. The chemical filter according to claim 1 .

3. The filter medium includes an adsorbent. The chemical filter according to claim 1 or 2.

4. The method further includes a chemical attached to the adsorbent so as to adsorb at least one of an acid component, a base component, ozone, and hydrogen peroxide contained in the gas. The chemical filter according to claim 3 .

5. The adsorbent is activated carbon, an ion exchange resin, a molecular sieve, an activated alumina, a silica gel, a zeolite, or a metal organic framework. The chemical filter according to claim 3 .

6. The filter medium includes a first filter medium and a second filter medium. The chemical filter according to claim 1 or 2.

7. The filter further includes a partition material disposed between the first filter medium and the second filter medium. The chemical filter according to claim 6.

8. The material constituting the partition material is the same as the material constituting the filter medium. The chemical filter according to claim 7.

9. The filter medium and the filter frame are partially joined together. The chemical filter according to claim 1 or 2.

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