JP5124069B2 - Air filter medium, air filter pack and air filter unit manufacturing method - Google Patents

Description

【００６７】
表１に示すように、湿度が４０％以上で濾材を作製した場合は、湿度が３０％の場合に比べ帯電量が大幅に抑えられるとともにリークの発生が抑えられていることが分かる。また、湿度の値が大きくなるほど、帯電量及びリークの発生量が抑えられており、湿度の上げることによるリーク発生の抑制効果が認められる。
［フィルタユニットの製造］
実施例１の雰囲気湿度８０％で製造したフィルタ濾材を、レシプロ折り機で高さ５.５ｃｍにプリーツ加工し、プリーツ後９０℃の温度をかけて折りくせをつけた。この後、プリーツされたフィルタ濾材を一旦開き（展開）、ポリアミドホットメルト樹脂製のスペーサーを塗布し、再度プリーツ状にレシプロ立ち上げ機で立ち上げ、大きさ５８ｃｍ×５８ｃｍに切断して、エアフィルタパックを得た。この時のプリーツ間隔は３.１２５ｍｍ／プリーツであった。
【００６８】
次に、外寸６１ｃｍ×６１ｃｍ、内寸５８ｃｍ×５８ｃｍ、厚さ６.５ｃｍのアルマイト加工アルミニウム製枠を用意し、この枠内にプリーツ加工されたエアフィルタパックを入れ、ウレタン接着剤でエアフィルタパック周囲とアルミニウム枠とをシールしてエアフィルタユニットを作製した。
＜実施例２＞
クリーンルーム内の雰囲気湿度を３０％、４０％、５０％、６０％、８０％にコントロールして、上記フィルタユニットの作製を行った。
【００６９】
上記実施例２のエアフィルタユニットについて測定した圧力損失、捕集効率、リークの有無について、表２に示す。
【００７０】
【表２】

【００７１】
表２に示すように、湿度が４０％以上で濾材を作製した場合はリークの発生が無く、湿度が３０％の場合に比べ捕集効率が高いことが分かる。また、湿度の値が大きくなるほど、リークの程度が小さくなり、この結果、捕集効率が高くなることが分かる。
【００７２】
【本発明の効果】
本発明によれば、所定の雰囲気湿度に管理されたクリーンルーム内でエアフィルタ濾材等の作製が行われるため、静電気が発生するのを抑えることができ、これにより、静電気放電の発生によるリーク等のダメージを抑えることができる。
【図面の簡単な説明】
【図１】本発明の一実施形態によるフィルタ濾材の製造方法の概要の一部を示す。
【図２】本発明の一実施形態によるフィルタ濾材の製造方法の概要の一部を示す。
【図３】本発明の一実施形態によるフィルタパックの製造方法の概要の一部を示す。
【図４】本発明の一実施形態によるフィルタパックの製造方法の概要の一部を示す。
【図５】本発明の一実施形態によるエアフィルタユニットの製造方法の概要の一部を示す。
【図６】エアフィルタユニットの圧力損失の測定装置を示す模式図。
【符号の説明】
１３ フィルタ濾材
２５ フィルタパック
２６ 枠体[0001]
BACKGROUND OF THE INVENTION
  The present invention relates to an air filter medium, an air filter pack, and an air filter unit manufacturing method.
[0002]
[Prior art]
  High cleanliness air filter units such as HEPA (: High Efficiency Particulate Air) filters and ULPA (: Ultra Low Penetration Air) filters are used in clean rooms and semiconductor manufacturing equipment that require high cleanliness. . These air filter units are provided with a filter medium for allowing air to pass therethrough and collecting suspended fine particles. As this type of conventional filter medium, a filter medium made of glass fiber has been used.
[0003]
  When producing filter media, static electricity may be generated when the filter media comes into contact with a roll or the like. However, in filter media made of glass fiber, static electricity itself is not generated much, and static electricity is generated and discharged. Even if this occurs, the thickness of the filter medium is usually as thick as 200 to 400 μm, so that damage such as leakage did not occur.
[0004]
[Problems to be solved by the invention]
  However, when a porous film made of polytetrafluoroethylene (hereinafter referred to as PTFE) is used as a filter medium used in the above-mentioned HEPA and ULPA filters, static electricity is likely to be generated as shown in the charge train, When static electricity is accumulated and static electricity discharge occurs, the thickness of the PTFE porous film is small, and thus the inventors' research has revealed that damage such as leakage can occur.
[0005]
  The reason why such a difference occurs depending on the material of the filter medium is that the PTFE filter medium is composed of PTFE of the filter layer and polyolefin of the support material, but as shown in the charged column, PTFE, polyolefin, etc. are on the negative side. This is because the conventional glass filter medium is less likely to generate static electricity because the glass itself belongs to the central region of the charged column.
[0006]
  In addition, the generation of static electricity is greatly influenced by the atmospheric humidity in the room. The smaller the relative humidity, the higher the electrostatic voltage generated. This is because when the relative humidity increases, static electricity is easily neutralized with moisture in the air and easily released to the atmosphere.
[0007]
  An object of the present invention is to produce an air filter medium, an air filter pack, and an air filter unit in which leakage is suppressed.
[0008]
[Means for Solving the Problems]
  In the manufacturing method of the air filter medium of Claim 1,1 μm or more and 100 μm or less of film thicknessPolytetrafluoroethyleneThe filter medium has a trapping efficiency of 99.97% or more when the particle diameter is 0.3 μm or more when the filter medium permeating wind speed is 1.4 cm / sec. Used for an air filter unit having a pressure loss of 50 Pa or more and 500 Pa or less when the permeation wind speed is 1.4 cm / sec.Air filter media,Relative humidity60It is produced in a clean room controlled to be 80% to 80%.
[0009]
  As described above, when the air filter medium is produced, static electricity may be generated due to winding by a roll, contact with other members, etc., and electrostatic discharge may occur. The air filter medium is damaged, and air leaks from the damaged part without trapping airborne particulates.
[0010]
  Therefore, in this method of manufacturing an air filter medium, the relative humidity in the clean room where the air filter medium is produced is controlled within a predetermined range, and the air filter medium is produced in such a room, so that the air filter medium etc. In this way, static electricity is prevented from being accumulated in the air filter, and leakage in the air filter medium is suppressed.
[0011]
Also,As described above, the air filter medium is produced in a room where the relative humidity is controlled within a predetermined range, thereby preventing electrostatic discharge.SuppressionLeakage and other damage can be suppressed, but by managing this relative humidity within a more appropriate range, the air filter media can be prevented from leaking.One layerIt has been clarified by the present inventors that it can be effectively suppressed.
[0012]
  Therefore, in this manufacturing method, an air filter medium is produced in a room where the relative humidity is controlled within the above range, and an air filter medium in which damage such as leakage is suppressed is obtained.
[0013]
Also,As described above, the PTFE porous membrane is more likely to generate static electricity than the conventional filter material made of glass fiber, as shown in the charged column, and therefore has a property of being easily damaged by leakage due to electrostatic discharge. doing. In addition, the reinforcing material thermally laminated on the PTFE porous membrane is generally made of a polyolefin resin, and, like the PTFE porous membrane, is more likely to generate static electricity than the glass filter medium.
[0014]
  Therefore, here, particularly in the case of producing an air filter medium composed of a PTFE porous membrane and its reinforcing material, the occurrence of electrostatic discharge is suppressed and damage such as leakage is prevented.
[0015]
Also,As described above, an air filter medium having a small collection layer such as a PTFE porous film is more likely to be damaged by electrostatic discharge than a glass filter medium. However, in this case, since the air filter medium is produced in a room where the relative humidity is controlled within a predetermined range, it is possible to suppress the occurrence of electrostatic discharge, and therefore, the air having a PTFE porous film with a small film thickness. Also in the filter medium, the occurrence of leak can be effectively suppressed.
[0016]
Also,The air filter medium has a trapping efficiency of 99.97% or more of particles having a particle diameter of 0.3 μm or more when the filter medium permeation wind speed is 1.4 cm / sec and the filter medium permeation wind speed is 1.4 cm / sec. Is used for an air filter unit having a pressure loss of 50 Pa or more and 500 Pa or less.
[0017]
  The air filter unit having such performance generally has a standard as a HEPA filter, and the needs thereof are increasing as an air filter unit suitable for use in a space where high cleanliness is required in recent years. However, since the air filter medium used as such an air filter has a fine fiber structure with a small fiber diameter, damage to the air filter medium due to electrostatic discharge is particularly large.
[0018]
  Here, when an air filter medium that can be used as such a HEPA filter is produced in a room controlled at a predetermined relative humidity, the occurrence of damage such as leakage is suppressed.
[0019]
  Claim2The manufacturing method described in claimDescribed in 1In the production method, the air filter medium has a trapping efficiency of 99.9999% or more of particles having a particle diameter of 0.1 μm or more when the filter medium permeation wind speed is 1.4 cm / sec and a filter medium permeation wind speed of 1.4 cm. Used for an air filter unit having a pressure loss of 50 Pa or more and 500 Pa or less.
[0020]
  The air filter unit having such properties generally has a standard as a ULPA filter, and is suitable for use in a space where higher cleanliness is required than the HEPA filter. However, since the air filter medium used as such an air filter has a fine fiber structure with a smaller fiber diameter, damage to the air filter medium due to electrostatic discharge is further increased.
[0021]
  Here, when an air filter medium that can be used as such a ULPA filter is manufactured in a room controlled at a predetermined relative humidity, the occurrence of damage such as leakage is suppressed.
[0022]
  Claim3In the manufacturing method of the air filter pack described in 4, the relative humidity is6Claims in a clean room managed between 0% and 80%1 or 2An air filter pack is produced using the air filter medium obtained by the production method described in 1. above.
[0023]
  In air filter pack manufacturing, static electricity can be generated due to contact with other members, etc., but here too, since air filter packs are manufactured in a room controlled at a specified relative humidity, the occurrence of electrostatic discharge is suppressed. Damage can be suppressed.
[0024]
Also,In this manufacturing method, the air filter pack is manufactured in a room where the relative humidity is controlled within a more appropriate range, thereby suppressing the occurrence of electrostatic discharge and more effectively suppressing damage such as leakage.
[0025]
Also,In this manufacturing method, in particular, when an air filter pack is produced from an air filter medium composed of a PTFE porous membrane and its reinforcing material, the occurrence of electrostatic discharge is suppressed and damage such as leakage is prevented.
[0026]
Also,In this manufacturing method, particularly when an air filter pack is produced from an air filter medium using a PTFE porous film having a small film thickness, the occurrence of electrostatic discharge is suppressed and damage such as leakage is prevented.
[0027]
  Claim4The manufacturing method of the air filter pack according to claim3In the manufacturing method described in the manufacturing method, the air filter pack has a trapping efficiency of 99.97% or more of particles having a particle diameter of 0.3 μm or more when the filter medium permeation wind speed is 1.4 cm / second. And it is used for the air filter unit whose pressure loss is 50 Pa or more and 500 Pa or less when the filter medium permeation wind speed is 1.4 cm / sec.
[0028]
  In this manufacturing method, particularly when an air filter pack that can be used as a HEPA filter is manufactured, the occurrence of electrostatic discharge is suppressed and damage such as leakage is prevented.
[0029]
  Claim5The manufacturing method of the air filter pack according to claimDescribed in 3In the manufacturing method, the air filter pack has a trapping efficiency of 99.9999% or more of particles having a particle diameter of 0.1 μm or more when the filter medium permeation wind speed is 1.4 cm / second and a filter medium permeation wind speed of 1. It is used for an air filter unit having a pressure loss of 50 Pa or more and 500 Pa or less in the case of 4 cm / second.
[0030]
  In this manufacturing method, particularly when an air filter pack that can be used as a ULPA filter is manufactured, the occurrence of electrostatic discharge is suppressed and damage such as leakage is prevented.
[0031]
  Claim6In the manufacturing method of the air filter unit described in 2, the relative humidity is6An air filter unit is manufactured using the air filter pack obtained by the manufacturing method according to any one of claims 8 to 14 in a clean room managed at 0% or more and 80% or less.
[0032]
  In air filter unit manufacturing, static electricity can be generated due to contact with other members, etc., but here too, the air filter unit is manufactured in a room controlled at a specified relative humidity, so that the occurrence of electrostatic discharge is suppressed. It is possible to suppress damage such as leakage.
[0033]
Also,In this manufacturing method, damage such as leakage is more effectively suppressed by manufacturing the air filter pack in a room in which the relative humidity is controlled within a more appropriate range.
[0034]
Also,In this manufacturing method, in particular, when an air filter pack is produced from an air filter medium composed of a PTFE porous membrane and its reinforcing material, the occurrence of electrostatic discharge is suppressed and damage such as leakage is prevented.
[0035]
Also,In this manufacturing method, particularly when an air filter pack is produced from an air filter medium using a PTFE porous film having a small film thickness, the occurrence of electrostatic discharge is suppressed and damage such as leakage is prevented.
[0036]
  Claim7The manufacturing method of the air filter unit according to claimDescribed in 6In the production method of the above, when the filter medium permeating air speed is 1.4 cm / second, the collection efficiency of particles having a particle diameter of 0.3 μm or more is 99.97% or more and the filter medium permeating air speed is 1.4 cm / second Is used as an air filter unit having a pressure loss of 50 Pa or more and 500 Pa or less.
[0037]
  In this manufacturing method, particularly when an air filter pack that can be used as a HEPA filter is manufactured, the occurrence of electrostatic discharge is suppressed and damage such as leakage is prevented.
[0038]
  Claim8The manufacturing method of the air filter unit according to claimDescribed in 6In the production method of the above, when the filter medium permeating wind speed is 1.4 cm / second, the collection efficiency of particles having a particle diameter of 0.1 μm or more is 99.9999% or more and the filter medium permeating wind speed is 1.4 cm / second Is used as an air filter unit having a pressure loss of 50 Pa or more and 500 Pa or less.
[0039]
  In this manufacturing method, particularly when an air filter pack that can be used as a ULPA filter is manufactured, the occurrence of electrostatic discharge is suppressed and damage such as leakage is prevented.
[0040]
DETAILED DESCRIPTION OF THE INVENTION
[Method for producing filter medium]
   1 and 2 show an outline of a method for producing a filter medium in which an embodiment of the present invention is employed. In FIG. 1, 1 is an unwinding roll, 2 is a winding roll, 3-5 is a roll, 6 and 7 are heat rolls, and 8-12 are rolls. In FIG. 2, reference numeral 14 denotes an unwinding roll, 15 denotes a preheating zone, 16 denotes a stretching zone, 17 denotes a heat setting zone, 19 denotes a laminating roll, and 21 denotes a winding roll.
[0041]
  This method for producing a filter medium is performed in a clean room managed so that the atmospheric humidity is within a predetermined range. Specifically, the atmospheric humidity is 40 to 80%, but it is preferably 50 to 80% and more preferably 60 to 80% from the viewpoint that even a slight leak can be suppressed. When the humidity exceeds 80%, dew condensation occurs in the equipment, devices, etc. used in the filter medium production process, and problems particularly in the electrical system are likely to occur.
[0042]
  In the clean room in which the atmospheric humidity is controlled in this way, the porous film manufacturing process, the thermal laminating process, and the winding process are performed. In the porous film production process, the PTFE green film is biaxially stretched to produce a PTFE porous film by the process shown in FIG. 1 and the process shown in the left half of FIG. The film thickness of the PTFE porous membrane is 1 to 100 μm, but 1 to 50 μm is preferable and 1 to 30 μm is more preferable in terms of reducing pressure loss.
[0043]
  In the heat laminating step, the filter medium 13 is obtained by heat laminating the breathable support material 18 made of a nonwoven fabric on both sides of the PTFE porous membrane in the step shown in the right half of FIG.
[0044]
  In the winding process, the filter medium 13 is wound around the winding roll 21. When the filter medium 13 is manufactured by such a method, static electricity is generated even if the filter medium 13, the nonwoven fabric 18, etc. come into contact with a roll or other member because the room is controlled at a relatively high atmospheric humidity. Therefore, static electricity does not accumulate and electrostatic discharge does not occur, and the filter medium 13 and the like can be prevented from receiving damage such as leakage.
[0045]
  In particular, in the winding process, static electricity is likely to be accumulated in the wound filter medium 13, but this method can effectively suppress the occurrence of electrostatic discharge even during drying in winter.
[0046]
  The filter medium 13 manufactured by the method of the present embodiment can be used for a HEPA filter or a ULPA filter. However, these filters using a PTFE porous membrane have a very fine fiber diameter and are fine. Since it has a fiber structure and a small film thickness, it is greatly affected by electrostatic discharge.
[0047]
  However, as described above, since the filter medium 13 is produced in a clean room in which the humidity is controlled within a predetermined range, leakage due to electrostatic discharge does not occur, and therefore, its high collection function is impaired. Can be suppressed.
[Method for manufacturing filter pack]
   3 and 4 show an outline of a method for manufacturing a filter pack in which an embodiment of the present invention is adopted.
[0048]
  The method for manufacturing the filter pack is performed in a clean room in which the atmospheric humidity is controlled as in the above embodiment. In such a room, an unwinding process, a pleating process, a developing process, a spacer applying process, and a repleating process are performed.
[0049]
  In the unwinding step, the filter medium 13 wound in the winding step of the above embodiment is unwound. In the pleating process, as shown in FIG. 3, the filter media 13 are alternately folded and processed into a corrugated shape (pleated), thereby forming a corrugated fold.
[0050]
  In the unfolding step, the pleated filter medium 13 is unfolded into a sheet shape. In the spacer application process, as shown in FIG. 4, the spacer 24 is applied to the developed filter medium 13.
[0051]
  In the pleating process, the filter medium 13 coated with the spacer 24 is pleated again to obtain the filter pack 25. Since the filter pack 25 obtained by such a method is manufactured in a clean room controlled to a predetermined atmospheric humidity, as in the above embodiment, it is possible to suppress the generation of static electricity, and thus electrostatic discharge. Can be suppressed, and damage such as leakage can be suppressed in the filter medium 13 and the filter pack 25.
[0052]
  In addition, the filter pack 25 can be used for HEPA and ULPA filters in the same manner as the filter medium 13, but is manufactured by this method to obtain a leak-free filter pack while maintaining a high collection function. be able to.
[Method of manufacturing air filter unit]
   In FIG. 5, the outline | summary of the manufacturing method of the air filter unit by which one Embodiment of this invention was carried out is shown.
[0053]
  The manufacturing method of the air filter unit is performed in a clean room in which the atmospheric humidity is controlled as in the above embodiment. In such a room, a packing process, a removing process, and an assembling process are performed.
[0054]
  In the packing process, the filter pack 25 obtained in the above embodiment is once packed in a bag until the subsequent assembly process is performed in order to prevent adhesion of organic substances and the like.
[0055]
  In the take-out step, the packed filter pack 25 is taken out from the bag in order to perform the next assembly step. In the assembly process, as shown in FIG. 5, the taken out filter pack 25 is incorporated into a frame body 26 to obtain an air filter unit.
[0056]
  Since the air filter unit obtained by such a method is manufactured in a room in which the atmospheric humidity is controlled within a predetermined range, as in the above embodiment, it is possible to suppress the generation of static electricity, and thus electrostatic discharge. It is possible to suppress the occurrence of damage such as leakage in the filter pack 25 and the air filter unit.
[0057]
  Moreover, although the air filter unit obtained here can be used as a HEPA and ULPA filter, the thing without a leak is obtained by manufacturing by this method, maintaining a high collection function.
[0058]
【Example】
[Presence of filter medium leakage]
  A measurement sample of the filter medium was set in a filter holder having a diameter of 100 mm, the inlet side was pressurized with a compressor, and the flow rate of air permeated with a flow meter was adjusted to 5.3 cm / second. In this state, the polydisperse DOP from the upstream side has a particle concentration of 10⁸Per particle / 300 ml, and the number of transmitted particles by particle size is obtained by a particle counter installed on the downstream side. From the ratio of the number of upstream and downstream particles, the particle size is 0.10 to 0.12 μm and 0.25 to 0.5. If the collection efficiency of DOP particles with a particle size of 0.25 to 0.35 μm is 100 times higher than the collection efficiency of DOP particles with a particle size of 0.10 to 0.12 μm, there will be no leakage. It was determined.
[Pressure loss of filter media (Pa)]
  The measurement sample of the PTFE porous membrane and the filter medium was set in a filter holder having a diameter of 100 mm, the inlet side was pressurized with a compressor, and the flow rate of air permeated with a flow meter was adjusted to 5.3 cm / second. And the pressure loss at this time was measured with the manometer.
[Filtering filter collection efficiency (%)]
  The measurement sample of the PTFE porous membrane and the filter medium was set in a filter holder having a diameter of 100 mm, the inlet side was pressurized with a compressor, and the flow rate of air permeated with a flow meter was adjusted to 5.3 cm / second. In this state, a polydisperse DOP having a particle diameter of 0.1 to 0.12 μm from the upstream side is added to a particle concentration of 10⁸Per particle / 300 ml, and the number of transmitted particles of DOP having a particle diameter of 0.1 to 0.12 μm by a particle counter (PMS LAS-X-CRT PARTLEMEEASURING SYSTEM INC. (PMS), the same applies hereinafter) installed downstream. Then, the upstream particle concentration was Ci and the downstream particle concentration was Co, and the collection efficiency of the measurement sample was calculated by the following formula.
[Equation 1]
Collection efficiency (%) = (1-Co / Ci) × 100
  For filter media with very high collection efficiency, measurement was performed with a longer suction time and a larger amount of sampling air. For example, if the suction time is 10 times, the number of counted particles on the downstream side is 10 times, that is, the measurement sensitivity is 10 times.
[Air filter unit leaks]
  For the measurement of the leak location of the air filter unit, JACA No. The test was conducted in accordance with 10C 4.5.4 (published by the Japan Air Cleaners Association, 1979 "Air Cleaner Performance Test Method Standard").
[0059]
   Using the apparatus shown in FIG. 6, silica particles generated from the Ruskin nozzle are mixed with clean air, and particles having a particle size of 0.1 μm or more have a concentration of 10⁸Pieces / ft^ThreeThe test fluid contained above is prepared. Next, the inspection fluid is passed through the air filter unit from the upstream side of the air filter unit so that the wind speed on the surface of the air filter unit is 0.5 m / sec. Then, while the scanning probe is scanned at a speed of 5 cm per second at a position 25 mm downstream of the air filter unit, the downstream air is sucked at 28.3 l / min, and the downstream silica particle concentration is measured by the particle counter. taking measurement. However, this scanning is performed over the entire surface of the filter medium of the air filter unit and the joint between the filter medium and the frame, and the strokes are slightly overlapped. The air filter unit leak criterion is that the collection efficiency is less than 99.999% as the first criterion, and if it exceeds that, the downstream silica particle size distribution is the upstream particle size distribution. The case where it became the same as that was judged as a leak.
[Pressure loss of air filter unit (Pa)]
   The apparatus shown in FIG. 6 was used to adjust the wind speed to pass through the filter medium after mounting the air filter unit to 1.4 cm / second, and the pressure loss before and after the air filter unit at that time was measured with a manometer.
[Air filter unit collection efficiency (%)]
   Using the apparatus shown in FIG. 6, after the air filter unit is mounted, the wind speed permeating the filter medium is adjusted to be 1.4 cm / second, and in this state, the particle diameter is 0.1 to 0.12 μm on the upstream side. Concentration of DOP particles 1 × 10⁹/ Ft^ThreeThen, the number of particles having a particle size of 0.1 to 0.12 μm on the downstream side was measured with a particle counter, and the collection efficiency of the measurement sample was calculated by the following formula, where the upstream particle concentration was Ci and the downstream particle concentration was Co. .
Collection efficiency (%) = (1-Co / Ci) × 100
  In addition, description of the code | symbol in FIG. 6 is as follows.
[0060]
  31: Blower, 32, 32 ': HEPA filter, 33: Test particle introduction tube, 34, 34': Rectifying plate, 35: Upstream test particle sampling tube, 36: Static pressure measurement hole, 37: Test filter Unit, 38: Particle collection tube for downstream test, 39: Laminar flow meter
[Measurement method of charge amount]
  The electrostatic charge amount was measured using a vibrating electrostatic potential measuring device “KSD-0103” manufactured by Kasuga Electric Co., Ltd.
[Manufacture of PTFE filter media]
  First, 100 parts by weight of PTFE fine powder having a number average molecular weight of 6,200,000 (“Polyflon Fine Powder F-104U” manufactured by Daikin Industries, Ltd.) and hydrocarbon oil as an extrusion aid (“Isopar” manufactured by Esso Oil Co., Ltd.) 25 parts by weight was added and mixed.
[0061]
  Next, this mixture was formed into a round bar shape by paste extrusion. And this round bar-shaped molded object was shape | molded by the calender roll heated at 70 degreeC, and the PTFE film was obtained. The film was passed through a hot air drying oven at 250 ° C. to evaporate and remove the extrusion aid, and an unfired film having an average thickness of 200 μm and an average width of 150 mm was obtained.
[0062]
  Next, this unsintered PTFE film was stretched at a stretch ratio of 5 in the longitudinal direction using the apparatus shown in FIG. The unsintered film was set on roll 1, and the stretched film was wound on take-up roll 2.
[0063]
  Next, the obtained stretched film in the longitudinal direction was stretched at a stretching ratio of 30 times in the width direction using a device (tenter) shown in the left half of FIG. The stretching temperature at this time was 290 ° C., the heat setting temperature was 360 ° C., and the stretching speed was 330% / second. A filter medium was obtained by thermally fusing the both sides of the PTFE porous membrane with the apparatus shown in the right half of FIG. 2 using the following nonwoven fabrics A and B.
Nonwoven fabric A: “Elves S0403WDO” PET / PE core / sheath nonwoven fabric, unit weight 40 g / m, manufactured by Unitika Ltd.²Nonwoven fabric B: “Elves T0403WDO” PET / PE core / sheath nonwoven fabric manufactured by Unitika Ltd., 40 g / m per unit area²
<Example 1>
  The filter medium was prepared by controlling the atmospheric humidity in the clean room to 30%, 40%, 50%, 60%, and 80%.
[0064]
  Table 1 shows the pressure loss, the collection efficiency, the charge amount, and the presence / absence of leaks measured for the filter media prepared at these atmospheric humidity. Regarding the charge amount, the charge amount on the roll surface 10 minutes after winding the filter medium was measured. Further, the presence or absence of leak was sampled from 20 filter media rolls, and the presence or absence of leak was measured.
[0065]
  Since the samples with a humidity of 40% and 50% had both leaked and non-leaked samples, the collection efficiency was not measured. This is because the values differ greatly between those with and without leaks.
[0066]
[Table 1]

[0067]
  As shown in Table 1, it can be seen that when the filter medium is manufactured at a humidity of 40% or more, the amount of charge is greatly suppressed and the occurrence of leakage is suppressed as compared with the case where the humidity is 30%. Further, as the humidity value increases, the amount of charge and the amount of leakage are suppressed, and the effect of suppressing the occurrence of leakage due to an increase in humidity is recognized.
[Manufacture of filter units]
  The filter medium produced in Example 1 at an atmospheric humidity of 80% was pleated to a height of 5.5 cm with a reciprocating fold, and after pleating, it was folded at a temperature of 90 ° C. After this, the pleated filter medium is once opened (developed), a spacer made of polyamide hot melt resin is applied, it is started up again with a reciprocating starter in a pleated form, cut into a size of 58 cm x 58 cm, Got a pack. The pleat interval at this time was 3.125 mm / pleat.
[0068]
  Next, an anodized aluminum frame having an outer dimension of 61 cm × 61 cm, an inner dimension of 58 cm × 58 cm, and a thickness of 6.5 cm is prepared, and a pleated air filter pack is placed in the frame, and an air filter is formed with urethane adhesive. The air filter unit was produced by sealing the periphery of the pack and the aluminum frame.
<Example 2>
  The filter unit was manufactured by controlling the atmospheric humidity in the clean room to 30%, 40%, 50%, 60%, and 80%.
[0069]
  Table 2 shows the pressure loss, the collection efficiency, and the presence or absence of leakage measured for the air filter unit of Example 2.
[0070]
[Table 2]

[0071]
  As shown in Table 2, it can be seen that when the filter medium was produced at a humidity of 40% or higher, no leakage occurred, and the collection efficiency was higher than when the humidity was 30%. It can also be seen that the greater the humidity value, the smaller the degree of leakage, resulting in higher collection efficiency.
[0072]
[Effect of the present invention]
  According to the present invention, since the air filter medium and the like are produced in a clean room controlled to a predetermined atmospheric humidity, it is possible to suppress the generation of static electricity, thereby preventing leakage due to the occurrence of electrostatic discharge. Damage can be suppressed.
[Brief description of the drawings]
FIG. 1 shows a part of an outline of a method for producing a filter medium according to an embodiment of the present invention.
FIG. 2 shows a part of an outline of a method for producing a filter medium according to an embodiment of the present invention.
FIG. 3 shows a part of an outline of a method for manufacturing a filter pack according to an embodiment of the present invention.
FIG. 4 shows a part of an outline of a method for manufacturing a filter pack according to an embodiment of the present invention.
FIG. 5 shows a part of an outline of a method for manufacturing an air filter unit according to an embodiment of the present invention.
FIG. 6 is a schematic diagram showing a pressure loss measuring device for an air filter unit.
[Explanation of symbols]
13 Filter media
25 filter pack
26 Frame

Claims (8)

Obtained by thermally laminating a reinforcing material to a porous film made of polytetrafluoroethylene having a thickness of 1 μm or more and 100 μm or less ,
The pressure loss is 50 Pa when the trapping efficiency of particles having a particle diameter of 0.3 μm or more is 99.97% or more when the filter medium permeation wind speed is 1.4 cm / sec and the filter medium permeation wind speed is 1.4 cm / sec. An air filter medium used for an air filter unit having a pressure of 500 Pa or less ,
Produced in a clean room where the relative humidity is controlled between 60 % and 80%.
Manufacturing method of air filter medium. The air filter medium has a trapping efficiency of 99.9999% or more of particles having a particle diameter of 0.1 μm or more when the filter medium permeation wind speed is 1.4 cm / sec and a filter medium permeation wind speed of 1.4 cm / sec. Used in an air filter unit in which the pressure loss in the case is 50 Pa or more and 500 Pa or less,
The method for producing an air filter medium according to claim 1 . In a clean room where the relative humidity is controlled to be 60 % or more and 80% or less, an air filter pack is produced using the air filter medium obtained by the production method according to claim 1 or 2 .
Manufacturing method of air filter pack. The air filter pack has a trapping efficiency of 99.97% or more of particles having a particle diameter of 0.3 μm or more when the filter medium permeation wind speed is 1.4 cm / sec and a filter medium permeation wind speed of 1.4 cm / sec. Used in an air filter unit in which the pressure loss in the case is 50 Pa or more and 500 Pa or less,
The manufacturing method of the air filter pack of Claim 3 . The air filter pack has a trapping efficiency of 99.9999% or more of particles having a particle diameter of 0.1 μm or more when a filter medium permeation wind speed is 1.4 cm / sec and a filter medium permeation wind speed of 1.4 cm / sec. Used in an air filter unit in which the pressure loss in the case is 50 Pa or more and 500 Pa or less,
The manufacturing method of the air filter pack of Claim 3 . In a clean room where the relative humidity is controlled to be 60 % or more and 80% or less, an air filter unit is manufactured using the air filter pack obtained by the manufacturing method according to any one of claims 3 to 5 .
Manufacturing method of air filter unit. The pressure loss is 50 Pa when the trapping efficiency of particles having a particle diameter of 0.3 μm or more is 99.97% or more when the filter medium permeation wind speed is 1.4 cm / sec and the filter medium permeation wind speed is 1.4 cm / sec. Used as an air filter unit of 500 Pa or less,
The manufacturing method of the air filter unit of Claim 6 . When the filtration medium permeation wind speed is 1.4 cm / second, the collection efficiency of particles having a particle diameter of 0.1 μm or more is 99.9999% or more and when the filtration medium permeation wind speed is 1.4 cm / second, the pressure loss is 50 Pa. Used as an air filter unit of 500 Pa or less,
The manufacturing method of the air filter unit of Claim 6 .

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