JP2006130369A - Filter unit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a small size, thin and high density filter unit using a filter medium with a high filling density. <P>SOLUTION: A separator 2 used for retaining a space between crests has a slope of wedge-like width by bending and/or joining a rod material and/or a plate material and the filter medium 1 having a bending resistance of 0.1-10 N×cm and a bulk density of 0.2-0.6 g/cc is pleated and the separator is clamped to unitize it. Thereby, the filter unit having a clearance of the space between the crests of the pleats of 0.25 mm to 2.5 mm can be created. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention is used in clean rooms in manufacturing plants for semiconductors, liquid crystals, foods, pharmaceuticals, etc., museums, art galleries, other general office buildings, etc., and removes and deodorizes fine dust, chemical pollutants and harmful substances present in the air. The present invention relates to a filter unit suitable for the purpose of removing substances, and more particularly to a chemical filter unit that adsorbs and removes chemical contaminants with an adsorbent.

  Traditionally, medium performance filters have been used in office buildings to remove dust in the air. In semiconductor and liquid crystal factories and the like, more advanced functions are required due to the problem of contamination with particulate matter, and higher performance dust filter units such as HEPA filters and ULPA filters are used. On the other hand, in recent years, as device integration and refinement progress in these fields, the influence of not only particulate substances but also molecular chemical pollutants is emerging as a problem, and these molecular contaminants are removed. Therefore, a unit such as a chemical filter has come to be used. The same unit is used to prevent contamination of products in factories such as food and pharmaceuticals, to prevent deterioration of exhibits and stored items in museums and museums, and to purify the office environment by increasing health-consciousness in general office buildings. Has also been deployed.

  The dust removal unit is made of nonwoven fabric mainly composed of glass fiber or synthetic fiber, whereas the chemical filter unit adsorbs and removes chemical contaminants by an adsorbent typified by activated carbon.

  Here, in general, a filter unit in which a sheet-shaped filter medium is folded in pleats is often used. The pleat folding type filter medium is housed in a frame with the pleat oriented vertically, and in order to secure an effective filtration area of the filter medium, a separating means for forming a predetermined interval between the pleat folds is provided. Typical separator means include a bead method in which resin beads orthogonal to the pleats are attached to the front and back surfaces of the sheet-like filter medium, a stabilizer method in which a comb-like cardboard stabilizer is inserted perpendicularly to the pleats, and a wavy shape is formed. There is a separator system in which an aluminum foil separator is inserted between folds of pleats (see, for example, Patent Document 1).

  Typical chemical filter units include granular activated carbon filled in a punching metal box and arranged in a W shape in the casing, or fibrous activated carbon felt pleated and fixed using a corrugated separator. It is an example (for example, refer to Patent Document 2).

  Recently, there is a demand for thinner filters due to the downsizing of air conditioners. Fan filter units (FFU) installed on the ceiling of clean rooms and chemical filter units attached to semiconductor manufacturing equipment are being made smaller and thinner. The demand for is becoming prominent. Some small and thin units are conventionally molded into a honeycomb shape using an extremely thin sheet containing activated carbon, but there is a problem that the amount of activated carbon to be filled is small and the life is short. If the amount of activated carbon contained in the sheet is increased, the amount of activated carbon per filter also increases, but at the same time, the sheet becomes thicker, and the opening of the honeycomb, that is, the flow path becomes narrower. Further, in the method of filling a large amount of sheets by reducing the honeycomb pitch, the flow path is similarly narrowed and the pressure loss is increased (for example, see Patent Document 3).

  Thus, a filter medium in which granular activated carbon is fixed in a synthetic fiber nonwoven fabric with a thermoplastic resin adhesive and formed into a sheet has been proposed (see, for example, Patent Document 4).

A filter medium having a high packing density represented by such an activated carbon filter has a high density, and thus enables the realization of a small and high removal rate filter unit. For example, the bead method is well known as a method of manufacturing a thin unit with a small depth. However, in the case of filter media solidified with high-density activated carbon and thermoplastic resin, it is very difficult to fold because it has high bending resistance and is difficult to fold, so it is very difficult to manufacture by bead molding. Met. In addition, when a normal corrugated separator is used, if the folding width is 3 mm or less, the pressure loss due to the structure of the separator is actually increased, and as a result, the ventilation resistance is increased. Furthermore, when the comb separator has a narrow folding width, an improvement in comb processing accuracy is required, resulting in an extreme increase in cost and difficulty in miniaturization.
JP 2002-361016 A JP-A-6-47232 Japanese Examined Patent Publication No.59-51423 JP 2002-273123 A

  An object of the present invention is to solve the above problems and to provide a small, thin, high-density filter unit using a filter medium having a high packing density.

  The present invention has been obtained as a result of intensive studies in view of such problems. That is, the present invention provides: (1) In a filter unit comprising a separator used as a means for holding a space between ridges and a pleated filter medium, the space between the pleat peaks Is a filter unit characterized in that the separator has a wedge-shaped width gradient by bending and / or joining the bar and / or plate. Yes, (2) The bending resistance measured in accordance with the slide method described in JIS L1096 “General Textile Testing Method” is 0.1 to 10 N · cm, and the bulk density is 0.2 to 0.6 g / cc. (3) Activated carbon between at least two layers of synthetic fiber sheets. A filter unit is a structure that is bonded by a thermoplastic resin.

  According to the present invention, it is possible to fold a high-filled sheet of activated carbon, which has a high density but is difficult to handle, into a unit by accurately pleating at a very low pitch. This contributes to higher efficiency and longer life of the chemical unit, and has the advantage of providing a compact, high-density filter unit that can effectively make a stiff and hard filter medium into a unit. .

This will be described in detail below.
FIG. 1 shows an overall schematic view of the filter unit of the present invention. The filter unit includes a pleated filter material 1 and a separator 2, and a frame 3 surrounding them. The filter unit of the present invention uses a pleated filter medium, and the space between the pleat mountain is preferably 0.25 mm or more and 2.5 mm or less. At this time, as shown in (FIG. 2) or (FIG. 3), the separator that holds the space between the peaks is bent and / or joined to the wedge-shaped width gradient by bending and / or joining the bars and / or plates. It is made up of things that have The space between the pleat peaks and the ridges, as indicated by (t) in FIG. 4, means the space between the pleat spaces formed by the separator, and the space (t) is 0.25 mm or more. 5 mm or less is preferable in view of a balance between an appropriate pressure loss and collection efficiency. More preferably, it is 0.28-2.3 mm, More preferably, it is 0.3-2.0 mm. When the space interval is smaller than 0.25 mm, the influence of minute fluff existing on the surface of the filter medium is greatly increased and the pressure loss increases, which is not preferable. On the contrary, when it is larger than 2.5 mm, the filter medium is used per unit volume. Since the amount decreases, the wind speed passing through the filter medium becomes high, which is not preferable because the pressure loss increases and the collection efficiency decreases.

  The separator used here is preferably a separator having a wedge-shaped width gradient by bending and / or joining a bar and / or a plate. Specifically, as shown in (FIG. 2), a flat plate is bent into a wedge shape and sandwiched between pleated filter media, or a predetermined thickness as shown in (FIG. 3). The wire is cut and bent in accordance with the height of the filter, and the bent portion is twisted at 90 degrees, and the twisted head portion is used so as to enter the space between the pleats. Further, as shown in FIG. 4, a wire having a predetermined thickness is folded into an E shape having a predetermined interval (corresponding to L in FIG. 4), and this is placed between pleated filter media. It can also be realized by pinching and twisting the portion that appears at the tip of the pleat at 90 degrees and supporting the spacing of the pleat at the twisted portion.

  Further, as shown in FIG. 5, a sheet metal punched into an E shape may be used, and a portion protruding from the pleat may be similarly folded into a wedge shape, and the folded portion may support the pleat interval. Furthermore, it is also possible to use a plate-like object or sheet in a wedge shape by stacking a plurality of sheets. The interval at which the plate material bent into a wedge shape is arranged, or the interval at which the wire whose head is bent 90 degrees (L in FIG. 4) is appropriately set depending on the size of the filter unit and the bending resistance of the filter medium. For this reason, there is no limitation, but when t is 2 mm, it is preferable to install them in the width direction at intervals of approximately 5 to 50 mm. The material of the separator includes plastics, wood, ceramics, paper, and fiber materials in addition to those made of metals such as aluminum, steel, stainless steel, copper, and silver, but is not limited to this as long as the material can hold the wedge. The filter unit obtained in this way has a unique inclination in the pleats, and the pleats are firmly fixed, so that the gas flow into the filter is good at high wind speeds, and is small and thin, and also in the high wind speed region. The pressure loss at is low.

  Further, the filter unit has a bending resistance of 0.1 to 10 N · cm measured according to the slide method described in JIS L1096 “General Textile Testing Method” and a bulk density of 0.2 to 0.6 g / It is desirable to use a filter medium that is cc. When the bending resistance of the filter medium is 0.1 to 10 N · cm, the workability at the time of pleating and the handling at the time of assembly are good, and the interval between the pleats at the time of unit formation is sufficiently formed. In this case, 0.15 to 9 N · cm is preferable, and 0.2 to 8 N · m is more preferable. When the bending resistance is less than 0.1 N · cm, the filter medium is not flexible, so there is a problem in handling, and when the separator is sandwiched and unitized, it is deformed and the voids formed by the separator are crushed. As a result, the pressure loss increases, which is not preferable. On the other hand, if it exceeds 10 N · cm, there is a problem that the rigidity is too large to be pleated, which is also not preferable. The bulk density of the filter medium is preferably 0.2 to 0.6 g / cc for obtaining an appropriate pressure loss and workability, preferably 0.25 to 0.55 g / cc, more preferably 0.3 to 0. 0.5 g / cc is more preferred. When the bulk density of the filter medium is less than 0.2 cc / g, the filter medium becomes soft, so when the separator is sandwiched and unitized, the filter medium is deformed, and the voids formed by the separator are crushed and pressure loss increases. It is not preferable. On the other hand, if it is larger than 0.6 cc / g, the pressure loss increases, which is not preferable. The thickness is not particularly limited, but a filter medium of 0.5 mm to 5 mm is suitable for making a unit.

  Such a filter medium has a structure in which activated carbon is bonded and fixed with a thermoplastic resin between at least two layers of fiber sheets, and the fiber sheet constituting the filter medium is composed of woven fabric and / or nonwoven fabric and / or knitted fabric. Is most preferred for use as a chemical unit. As the activated carbon, granular activated carbon is preferable, and the average particle size is preferably 100 to 600 μm, more preferably 200 to 500 μm on the average according to JIS standard sieve (JIS Z8801) in consideration of air permeability and workability. . When the average particle size is less than 100 μm, the pressure loss becomes too large to obtain a certain adsorption capacity, and when the average particle size exceeds 600 μm, the removal rate of chemical contaminants becomes extremely worse, Workability at the time of pleating deteriorates. In addition, this granular activated carbon is obtained by performing a predetermined particle size adjustment using a normal classifier. The kind of granular activated carbon is not specifically limited, For example, coconut shell type | system | group, wood type | system | group, coal type | system | group, a pitch type | system | group etc. are used suitably. In terms of shape, crushed charcoal, granulated charcoal, bead charcoal and the like are preferably used. In addition, 20 weight% or more of toluene adsorption amount when measuring based on JISK1474 of this granular activated carbon is preferable. This is because high adsorption performance is required for a small amount of chemical pollutants. Normally, activated carbon exhibits particularly good adsorption characteristics for nonpolar molecular substances, but granular activated carbon on which various chemical adsorbents are previously supported or attached can be used in order to improve the adsorption characteristics for polar substances. For example, for aldehyde gases and nitrogen compounds such as nitrogen dioxide, sulfur compounds such as sulfur dioxide and hydrogen sulfide, and acidic polar substances such as acetic acid, amine compounds such as ethanolamine, polyethyleneimine, aniline and anisidine Sodium hydroxide, potassium hydroxide, guanidine phosphate, potassium carbonate, sodium hydrogen carbonate, etc. are preferably used. For basic polar substances such as ammonia, methylamine, trimethylamine, pyridine, phosphoric acid, Acid, malic acid, ascorbic acid and the like are preferably used.

The fiber sheet, which is a constituent material of the filter medium, is preferably a non-woven fabric made of synthetic fibers. However, the form is not particularly limited as long as processability during processing, tearing, pressure loss, and scattering of activated carbon are taken into consideration. For example, when using a non-woven fabric, long fibers made of synthetic fibers having a fiber diameter of 15 to 30 μm are used, and the basis weight per layer is 20 to 50 g / m ² , which is measured according to the strip method described in JIS L1096 “General Textile Testing Method”. It is desirable that the tensile strength in the longitudinal direction is 40 N / 5 cm width or more and the elongation is 15% or more. The range of the fiber diameter and the basis weight are important in order to prevent the activated carbon from falling off and scattering. When the fiber diameter is less than 15 μm or when the basis weight is 50 g / m ² or more, the pressure loss becomes high, which is not preferable. Further, the region of tensile strength and elongation in the longitudinal direction is important in order to prevent the synthetic fiber nonwoven fabric from being broken at the apex of the pleat because the workability during pleating is good. In addition to non-woven fabrics, woven fabrics and knitted fabrics are used.

  The weight ratio of the thermoplastic resin joining the activated carbon and the fiber sheet to the granular activated carbon is preferably 15 to 50%, more preferably 20 to 40%. The fiber sheet, the thermoplastic resin, and the granular activated carbon are integrated by arranging a mixture of the granular activated carbon and the thermoplastic resin (which becomes an adsorption layer) between the two layers of fiber sheets and press-bonding them while heating. If it is less than 15%, the granular activated carbons are not sufficiently bonded to each other, and the activated carbon may drop off or the pleat shape of the filter material may be destroyed. When it exceeds 50%, the adsorbing layer becomes harder than necessary, which causes deterioration of workability during pleating.

  The shape of the thermoplastic resin is preferably powder or granular, and the average particle size is preferably 10 to 120 μm on average as measured by JIS standard sieve (JIS Z8801). In the case of less than 10 μm, when mixed with granular activated carbon and sprayed on a synthetic fiber nonwoven fabric, the resin powder rises and uniform spraying becomes difficult. If it exceeds 120 μm, mixing with granular activated carbon tends to be non-uniform, and the number of particles decreases, so a very large amount of resin is required to select a desired adhesion state, which is not preferable.

  In addition, the adhesive used to bond and seal the thermoplastic resin, fiber sheet, adhesive sheet made of thermoplastic fiber, and pleated filter media and the filter frame all generate gaseous organic matter. It is important that the amount is small, and it is preferable that the total amount of gaseous organic substances generated during heating at 100 ° C. is 1 μg / g or less. A method called “P & T (Purge & Trap) -GC / MS (Gas Chromatograph / Mass Spectrum) Method” or “Dynamic Headspace Method” is generally used as a method for analyzing the heat generated gas. In this method, a predetermined amount of sample is collected, heated for a predetermined time while flowing helium gas, volatile components are collected and concentrated in a cooled adsorption tube, and then heated and desorbed again with a carrier gas, and introduced into GC / MS for analysis. It is a method. Since this method usually vaporizes gaseous organic matter by heating, the amount generated in a space controlled at room temperature such as a clean room is extremely small due to the relationship between temperature and vapor pressure, and the total amount generated under heating at 100 ° C. By using a material having a particle size of 1 μg / g or less, the risk of causing problems in actual use becomes extremely low. The thermoplastic resin, the synthetic fiber nonwoven fabric, the adhesive sheet made of thermoplastic fibers, the material of the adhesive for adhering and sealing the filter filter medium and the filter frame is not particularly limited, thermoplastic ones, For example, polyolefins, polyesters, polyamides, EVAs, etc. can be used, but they do not contain or contain additives such as tackifiers, antioxidants, plasticizers, mold release agents, etc. It is preferable.

The present invention will be described in further detail with reference to the following examples. However, the following examples are not intended to limit the present invention, and all modifications that do not depart from the spirit of the present invention are included in the technical scope of the present invention. .

Example 1
A PET long fiber with an average fiber diameter of 17 μm is obtained by adding 20% of a powdered polyethylene adhesive with an average particle diameter of 12 μm to a coal-based granular activated carbon with an average particle diameter of 300 μm and stirring and mixing until uniform. An adhesive composed of a spunbond nonwoven fabric having a basis weight of 40 g / m ² , a tensile strength in the longitudinal direction of 120 N / 5 cm and an elongation of 25% measured in accordance with the strip method described in JIS L1096, and a polyamide fiber After spraying on the stacked sheets so that the granular activated carbon filling amount is 600 g / m ² (including the powdered polyethylene adhesive filling amount is 120 g / m ² ), the adhesive sheet and the spunbond nonwoven fabric With the same material stacked and sandwiched, it was heated and pressure-bonded for 30 seconds under the conditions of a temperature of 140 ° C. and a pressure of 5 N / cm ^2. A filter medium of mm was obtained. At this time, the bending resistance of the filter medium was 5.3 N · cm, and the density was 0.4 g / cc. This was pleated by 28 pleats at a height of 50 mm and slit at a width of 180 mm. Further, a stainless steel plate having a thickness of 80 μm was punched out at 38 mm × 3 mm and bent at the center to form a separator having a wedge shape with a width of 1 mm. This was sandwiched between each pleat with a total of 4 sheets between the width of 180 mm and 2 sheets at both ends and the center. The interval between each wedge-shaped separator was 56 mm. A pleated folded filter medium sandwiching the wedge-shaped separator was surrounded by an aluminum plate frame having a thickness of 1 mm, and bonded and sealed with a polyamide adhesive to form a unit. The amount of activated carbon of this unit was 223 g / unit, and the pressure loss was 39 Pa at an air volume of 1.5 m ³ / min.

(Example 2)
A 20-% powdered polyethylene adhesive with an average particle size of 12 μm is added to coal-based granular activated carbon with an average particle size of 300 μm, and the mixture is stirred and mixed until substantially uniform. A spunbonded non-woven fabric having a basis weight of 40 g / m ² , measured in accordance with the strip method described in JIS L1096, having a tensile strength in the longitudinal direction of 120 N / 5 cm, an elongation of 25%, and a polyamide fiber After spraying the adhesive sheet so that the granular activated carbon filling amount is 350 g / m ² (of which the powdered polyethylene adhesive filling amount is 70 g / m ² ), the adhesive sheet and the spunbond nonwoven fabric while sandwiched overlay the same, temperature 140 ° C., heated and pressure-bonded for 30 seconds under a pressure of 5N / cm ^2, thickness 1 It was obtained 0mm of the filter media. At this time, the bending resistance of the filter medium was 0.5 N · cm, and the density was 0.4 g / cc. This was processed into pleats for 39 mountains at a height of 50 mm and slit at a width of 180 mm. Also, a 0.5 mm thick stainless steel wire is bent at a length of 55 mm, the 5 mm portion of the bent portion is twisted to 90 degrees, the width of the twisted head portion is 1 mm, and the bent portion and the portion A separator having an interval (“L” in FIG. 4) of 40 mm was prepared. The separator was sandwiched between the pleats and the pleat piles. The processed pleated filter medium sandwiched with the processed stainless steel wire was surrounded by an aluminum plate frame having a thickness of 1 mm, and bonded and sealed with a polyamide adhesive to form a unit. The amount of activated carbon of this unit was 181 g / unit, and the pressure loss was 24 Pa at an air volume of 1.5 m ³ / min.

(Comparative Example 1)
The filter medium prepared in Example 1 was folded in 20 pleats, and an 80 μm thick aluminum wave separator having a height of 50 mm × 180 mm and a wave height of 3 mm was sandwiched between the pleats. A pleated folded filter medium sandwiched between plates was surrounded by an aluminum plate frame having a thickness of 1 mm, and bonded and sealed with a polyamide adhesive to form a unit. The amount of activated carbon in this unit was 168 g / unit, and the pressure loss was 55 Pa at an air volume of 1.5 m ³ / min.

(Comparative Example 2)
Nine pleats are folded at a peak height of 50 mm and a felt of 600 g / m ² , 10 mm thick felt (density 0.06 g / cc, bending resistance 1.0 N · cm) made of fibrous activated carbon with a fiber diameter of 17 μm, 180 mm wide Slit. The 1 mm wedge-shaped separator used in Example 1 was sandwiched between each pleat, with a total of 4 sheets between the width of 180 mm and two at both ends and the center. The distance between each stainless steel plate was 56 mm. The pleated folded filter medium sandwiched with the stainless steel plate was surrounded by an aluminum plate frame having a thickness of 1 mm, and bonded and sealed with a polyamide adhesive to form a unit. The amount of activated carbon in this unit was 98 g / unit, and the pressure loss was 140 Pa at an air volume of 1.5 m ³ / min.

  The filter unit of the present invention makes it possible to form a pleated folded high-density filter medium at a fine pitch. This greatly contributes to a thin, small and high density filter unit, particularly a chemical filter unit for removing a small amount of chemical substances generated in a small space such as a clean bench used in a semiconductor manufacturing factory.

It is the whole filter unit perspective view in the present invention. It is a perspective view which shows the detail of a structure with the filter medium and the plate-shaped separator by which the pleat folding in the filter unit in this invention was carried out. It is a perspective view which shows the detail of the structure of the filter medium and the rod-shaped separator which were pleat-folded in the filter unit in this invention. It is the schematic of the structure of the filter medium which carried out the pleat folding in the filter unit in this invention, and the E-shaped separator obtained by bending of a wire, and sectional drawing of a pleat. It is the schematic of the structure of the filter filter medium by which the pleat folding in the filter unit in this invention was carried out, and the E-shaped separator obtained by punching a board | plate material, and sectional drawing of a pleat.

Explanation of symbols

1: Filter media 2: Separator 2a: Wedge-shaped separator 2b: Torsion separator 3: Frame 4a: Separator 4b in which a wire is bent 4b: Separator with punched plate material and a wedge at the tip

Claims (3)

  In the filter unit composed of the filter medium that is a separator and the means used for holding the space between the ridges is a separator, the space between the pleats and the ridges is 0.25 mm to 2.5 mm. A filter unit, wherein the separator has a wedge-like width gradient by bending and / or joining a bar and / or a plate.   From a filter medium having a bending resistance of 0.1 to 10 N · cm and a bulk density of 0.2 to 0.6 g / cc measured according to the slide method described in JIS L1096 “General Textile Testing Method” The filter unit according to claim 1, wherein the filter unit is configured.   The filter unit according to any one of claims 1 to 2, wherein the filter medium has a structure in which activated carbon is bonded and fixed by a thermoplastic resin between at least two fiber sheets.