JP6028217B2 - AIR FILTER, ITS MANUFACTURING METHOD, AND AIR CLEANING DEVICE EQUIPPED WITH THE AIR FILTER - Google Patents

Description

  The present invention relates to an air filter incorporated in an air conditioner and the like, a method for manufacturing the air filter, and an air purifier equipped with the air filter.

  As a conventional air filter, an air filter is configured by processing an air filter nonwoven fabric, which is a filter medium, alternately and repeatedly in a mountain fold and a valley fold and processing it into a pleated shape. As this air filter non-woven filter medium, one having the same basis weight on a plane where the non-woven filter medium is developed is known (for example, see Patent Document 1).

Hereinafter, the nonwoven fabric filter medium for air filters will be described. The nonwoven fabric for air filter of Patent Document 1 is a melt blown nonwoven fabric composed of a single layer mainly composed of polyolefin and / or polyester, and has a basis weight of 80 to 140 g / m ² and a thickness of 0.5 to 1.5 mm. , And the single layer has a fill factor gradient.

JP 2009-106824 A

  In an air filter composed of such a conventional non-woven filter medium for an air filter, the air volume passing through the filter differs depending on the distance from the air blowing means, that is, the air volume is large in the vicinity of the air blowing means and decreases in the distance. There is a problem that the entire filter cannot be used efficiently, leading to an increase in pressure loss and a decrease in dust collection efficiency.

  Therefore, the present invention solves the above-mentioned conventional problems, and makes the air volume passing through the air filter uniform regardless of the distance of the air blowing means to efficiently use the entire filter, increasing pressure loss and collecting efficiency. The purpose is to prevent the deterioration of

In order to achieve the above object, a square plate-shaped filter medium part and a shape holding part for holding the filter medium part in a pleated shape are provided, and the filter medium part is blown to the base material part and the base material part. It is formed from a fine fiber layer provided on the upstream surface of the air flow and a protective layer covering the fine fiber layer, and the basis weight of the fine fiber layer is at least in the center from a pair of opposite ends of the filter medium part. a multi-home air filter, much in the central portion along the mass per unit area of the fine fiber layer in the fold line direction of the pleats, to provide an air filter that is less at the end.

  According to the air filter of the present invention, the basis weight of the fine fiber layer is larger in the central part than at least one pair of opposite ends of the filter medium part, so that the air volume passing through the air filter is made uniform, Since the entire filter can be used efficiently, a pleated air filter with low pressure loss and high dust collection efficiency can be realized.

  In addition, since the present invention uses the low pressure loss air filter of the present invention, it is possible to reduce the number of rotations of the motors and blades that are the blowing means, so that the operation sound is quiet and the power consumption is low. A low and high dust collection efficiency air purifier can be realized.

Sectional drawing which shows Embodiment 1 of this invention Perspective view of the air filter Cross section of the air filter Schematic showing a side view of the air filter manufacturing method Schematic showing a front view of the manufacturing method of the same air filter Cross-sectional view of the air filter medium Schematic sectional view showing a main body configuration of an air cleaning device with a humidifying function in Embodiment 2 of the present invention.

An air filter according to claim 1 of the present invention is provided with a square plate-shaped filter medium part and a shape holding part for holding the filter medium part in a pleat shape, and the filter medium part includes a base material part and the base material part. A pair of both end portions of the fine fiber layer formed on a surface on the upstream side of the air flow blown to the air flow and a protective layer covering the fine fiber layer, the basis weight of the fine fiber layer facing at least the filter medium portion a multi-home air filter more central, often in the middle portion along the mass per unit area of the fine fiber layer in the fold line direction of the pleats, having the features that are less at the end. By having such a feature, the amount of air passing through the air filter can be made uniform and the entire filter can be used efficiently, so that the pressure loss can be reduced and the dust collection efficiency can be improved.

In particular, the fabric weight of the fine fiber layer is large at the central portion along the pleated crease line direction and small at the end portion, or large at the central portion along the direction substantially perpendicular to the crease line, and small at the end portion. By adopting a configuration , when only one direction of the air filter is away from the air blowing means, the weight per unit area near the air blowing means can be increased, and the amount per unit area at the far end can be reduced. Can be used efficiently.

In the air filter according to claim 2 of the present invention, the basis weight of the fine fiber layer is preferably 0.1 to 10.0 g / m ² . A basis weight of less than 0.1 g / m ² is not preferable because the amount of fibers is small and the dust collection efficiency becomes low. On the other hand, if the basis weight is 10.0 g / m ² or more, the amount of fibers is large and the pressure loss becomes large.

The air filter according to claim 3 of the present invention, the average and the fiber diameter 50~1000nm of fine fiber layer, since thinner than normal fiber diameter (about 2 to 20 [mu] m), low pressure loss and high dust collecting efficiency It can be used as a filter medium.

The air filter according to claim 4 of the present invention, the substrate unit and the spun bond method is the protective layer, dry or wet method, melt blown method, spun bond method, pulp fibers produced by such air-laid process, resin fibers It is preferable to use a non-woven fabric containing carbon fiber and inorganic fiber, or at least one of them. In particular, a non-woven fabric having a low pressure loss is preferable, and the pressure loss of the air filter can be reduced by using this non-woven fabric.

In the air filter according to claim 5 of the present invention, the protective layer may include a low melting point resin material. Thereby, a protective layer fuse | melts by low-temperature heating, and can bond 3 layers, a base material, a fine fiber, and a protective layer.

According to a sixth aspect of the present invention, there is provided an air cleaning device comprising: a main body case having an air inlet and an exhaust port; an air blowing means provided in the main body case; and an air filter at the air inlet of the main body case. It is attached. As a result, it is possible to provide an air purifier that has quiet operation noise , low power consumption, and high dust collection efficiency .

Further, humidifying function with air cleaning equipment according to claim 7 of the present invention is provided with a humidifying unit in the air cleaning path of the air cleaning device. Since a sufficient air volume can be secured at the lower part of the filter near the humidifying filter, the humidifying ability can be improved.

In the air filter manufacturing method according to claim 8 of the present invention, the fine fiber layer is preferably formed by an electrospinning method. This method is a method of forming a fine fiber layer by spraying a solution by applying a high voltage to a polymer solution, and the fiber diameter of the obtained fine fiber depends on the applied voltage, the solution concentration, etc. Any fiber diameter can be obtained by adjusting these conditions.

In the air filter manufacturing method according to claim 9 of the present invention, a nozzle that discharges fine fibers is arranged on the surface side of the plate-like base material portion in the conveying direction of the base material portion, and an electrode plate is provided on the back surface side. The fine fiber layer is formed by opposingly arranging, changing the potential of the electrode plate stepwise in a direction substantially perpendicular to the conveying direction of the base material portion, and forming a fine fiber layer on the entire surface of the base material portion with a nozzle. A method of manufacturing an air filter that forms a fine fiber layer that is larger in the center than at a pair of opposite ends at least in a set, and the basis weight can be reduced by simply applying a voltage without changing the conveyance speed of the substrate. Since the changed fine fiber layer can be formed, high mass productivity can be obtained.

Hereinafter, preferred embodiments of an air filter and an air cleaning device of the present invention will be described in detail with reference to the drawings.

( Embodiment 1 )
As shown in FIG. 1, the air purifier equipped with the air filter of the first embodiment includes a blower 2 and an air filter 3 in a main body case 1.

  The main body case 1 has a substantially vertically long box shape. The main body case 1 is provided with a substantially square-shaped intake port 4 on the front side surface portion thereof, and the main body case 1 is provided with a substantially square-shaped exhaust port 5. Yes. The exhaust port 5 is provided with a wind direction louver 6.

  The air blowing means 2 is provided in an air passage between the air inlet 4 and the air outlet 5 of the main body case 1, and has a scroll-shaped casing 7 and a blade 8 which is a centrifugal air fan provided in the casing 7. And the electric motor 9 that rotates the blade 8. The air filter 3 is located at the air inlet 4 of the main body case 1. Air blown into the body case 1 from the air inlet 4 by the air blowing means 2 is sent to the air outlet 5 via the air filter 3. That is, the indoor air is cleaned by the air filter 3 and blown into the room.

  As shown in FIGS. 2 and 3, the air filter 3 is formed of a pleated filter medium part 10 and a shape holding part 11 for holding the filter medium part 10 in a pleat shape.

  The air filter 3 is obtained by bending a flat plate-shaped filter medium portion 10 into a pleated shape, that is, a waveform. The shape holding part 11 is formed from a square-shaped frame part 12 and an adhesive member 13 provided between the frame part 12 and the filter medium part 10. That is, the frame portion 12 is positioned on the periphery of the pleated filter medium portion 10, and the pleated filter medium portion 10 is fixed to the frame portion 12 by the adhesive member 13.

  The filter medium part 10 includes a base material part 15, a fine fiber layer 16 provided on the upstream side surface of the air flow blown to the base material part 15, and a protective layer 17 that protects the fine fiber layer 16.

  Next, the fine fiber layer 16 will be described.

The feature in the first embodiment resides in the fine fiber layer 16 of the air filter 3. That is, the basis weight of the fine fiber layer 16 covered with the protective layer 17 on the upstream side of the air flow of the base material portion 15 is large in the central portion in the vicinity of the blade 8 and is small in the upper and lower end portions in the distance. This is a feature.

  That is, a pleat-shaped filter medium part 10 and a shape holding part 11 for holding the filter medium part 10 in a pleat shape are provided. The filter medium part 10 includes a base material part 15 and an air flow blown to the base material part 15. Are formed from the fine fiber layer 16 provided on the upstream side of the filter and the protective layer 17 that protects the fine fiber layer 16, so that the fine fiber layer 16 reduces the pores and improves the collection efficiency, and the filter medium portion 10 is pleated. By making the shape, the surface area of the fine fiber layer 16 is increased, so that an increase in pressure loss can be suppressed.

  However, if the basis weight of the fine fiber layer 16 is constant, the pressure loss of the air filter 3 held in a pleated shape becomes uniform, and the upper and lower ends of the air filter 3 at a position away from the blades 8 that are centrifugal blower fans. Then, the air volume is smaller than that at the center, and the air filter 3 cannot be used effectively. As a result, the pressure loss of the air filter 3 increases and the dust collection efficiency decreases.

  Therefore, by increasing the weight per unit area of the fine fiber layer at the central portion rather than at the upper and lower ends that are at least a pair of opposite ends, the pressure loss at the upper and lower ends of the air filter 3 is reduced, and the air volume is increased. As a result, the pressure loss of the air filter 3 is reduced and the dust collection efficiency is improved, so that the entire filter can be used efficiently.

  The fine fiber layer 16 is made of fibers having an average fiber diameter of 50 to 1000 nm obtained by processing a known polymer using a processing technique such as an electrospinning method or a melt spinning method described later. Fibers having an average fiber diameter of 50 to 1000 nm are generally referred to as nanofibers, and since the fiber diameter is thin, the gap between the fibers is reduced and dust collection efficiency is improved. Furthermore, although the gap between the fibers is small, an increase in pressure loss can be prevented by an effect called a slip flow effect. That is, when the pressure loss of a filter medium made of nanofibers having the same dust collection efficiency is compared with that of a filter medium made of fibers exceeding 1000 nm, the pressure loss of the filter medium made of nanofibers is smaller.

  With known processing techniques such as electrospinning and melt spinning, spinning with an average fiber diameter of less than 10 nm is difficult, and fibers with an average fiber diameter of more than 1000 nm have a large gap between the fibers. In order to improve the efficiency, it is necessary to increase the weight per unit area or increase the thickness, thereby increasing the pressure loss, which is not suitable for the present invention. Further, the shape of the fibers forming the fine fiber layer 16 is not particularly limited. However, when a known processing method such as an electrospinning method is used, the cross section is substantially circular or elliptical.

  When the fine fiber layer 16 is produced by a known electrospinning method, it is necessary to use a polymer solution in which a polymer is dissolved in a solvent. Known polymer polymers include polyacrylonitrile, polyethylene, polypropylene, polyethylene oxide, polyethylene glycol, polyethylene terephthalate, polyethylene naphthalate, poly-m-phenylene terephthalate, poly-p-phenylene isophthalate, polymethacrylic acid, polymethyl methacrylate. , Polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropyrene copolymer, polyvinyl chloride, polyvinylidene chloride-acrylate copolymer, polytetrafluoroethylene, polyvinyl alcohol, polyarylate, polyacetal, polycarbonate, polystyrene, polyphenylene sulfide, polyamide , Polyimide, polyamideimide, aramid, polyimidebenzazole, polybenzimidazole , Polyglycolic acid, polylactic acid, polyurethane, cellulose compounds, polypeptides, nucleosides, polynucleotides, proteins, and enzymes, can be used mixtures thereof.

  Here, as a high molecular polymer, polyacrylonitrile is preferable from the viewpoint of easy availability and handling.

  The solvent for dissolving the polymer is not particularly limited as long as it is compatible with the polymer and can be dissolved. Examples of these solvents include water, alcohols, organic solvents, etc. Specific alcohols and organic solvents include acetone, chloroform, ethanol, isopropanol, methanol, toluene, tetrahydrofuran, benzene, benzyl alcohol, 1, Highly volatile solvents such as 4-dioxane, propanol, carbon tetrachloride, cyclohexane, cyclohexanone, methylene chloride, phenol, pyridine, trichloroethane, acetic acid, N, N-dimethylformamide (DMF), dimethyl sulfoxide (DMSO), N , N-dimethylacetamide (DMAc), 1-methyl-2-pyrrolidone (NMP), ethylene carbonate, propylene carbonate, dimethyl carbonate, acetonitrile, N-methylmorpholine-N-oxide, Tylene carbonate, γ-butyrolactone, diethyl carbonate, diethyl ether, 1,2-dimethoxyethane, 1,3-dimethyl-2-imidazolidinone, 1,3-dioxolane, ethyl methyl carbonate, methyl formate, 3-methyl oxazolidine Examples include solvents having relatively low volatility such as 2-one, methylpropionate, 2-methyltetrahydrofuran, and sulfolane. Alternatively, it is possible to use a mixture of two or more of the above solvents.

  In addition, when polyacrylonitrile is selected as the polymer, the solvent is preferably DMF. When polyvinyl alcohol or polyethylene oxide is selected as the polymer, water is preferably used as the solvent.

Further, the basis weight of the fine fiber layer 16 is preferably 0.1 to 10.0 g / m ² . The average thickness of the fine fiber layer 16 at this time is estimated to be about 5 μm although it depends on the filling state.

  The base material part 15 is a member which becomes a support body which supports the fine fiber layer 16 mentioned later. The base material part 15 and the protective layer 17 are made of pulp fiber, resin fiber, carbon fiber and inorganic fiber, or at least one of them produced by a spunbond method, a dry or wet method, a melt blown method, a spunbond method, an airlaid method, or the like. It is composed of non-woven fabric containing one.

  Further, the average diameter of the fibers constituting the base material portion 15 is preferably about 1 to 30 μm. When the average fiber diameter is 1 μm or less, the strength is weak, and when the average fiber diameter is 30 μm or more, the space between the fibers increases, and the fibers having an average fiber diameter of 50 to 1000 nm forming the fine fiber layer 16 penetrate deep into the base material portion 15. This is to increase the pressure loss.

  The material, shape, and length of the fiber are not particularly limited, but if the rigidity is too low, pleating becomes difficult and the productivity is lowered. Etc. are preferable.

  The protective layer 17 is a member that protects the fine fiber layer 16 described later. If the protective layer 17 includes a low melting point resin material, the protective layer 17 is melted by low-temperature heating, and the three layers of the base material portion 15, the fine fiber layer 16, and the protective layer 17 are bonded, There is an effect that it can be integrated. As an example of the protective layer 17 containing a low melting point resin material, a spunbond nonwoven fabric or a thermal bond nonwoven fabric containing a low melting point resin material, or paper using a low melting point resin material as a binder can be used.

  There are no particular restrictions on the basis weights of the base material part 15 and the protective layer 17, but if the basis weight is too large, the pressure loss increases, so that the pressure loss at a surface wind speed of 5.3 cm / s can be 15 Pa or less. It is only necessary that the basis weight is sufficient to support the fine fiber layer 16. Moreover, although it does not specifically limit about dust collection efficiency, when selecting the base material part 15 and the protective layer 17 which were mentioned above, it is estimated that it will become about 1 to 30% as a result.

As described above, the air filter 3 according to the first embodiment includes the filter medium part 10 and the shape holding part 11 that holds the filter medium part 10 in a pleated shape. The fine fiber layer 16 provided on the upstream surface of the air flow blown to the base material part 15 and the basis weight of the fine fiber layer 16 are at least larger in the center than a pair of opposite ends. Since the fine fiber layer 16 is thinner than the average fiber diameter of 50 to 1000 nm and the normal fiber diameter (about 2 to 20 μm), a pleated air filter with low pressure loss and high dust collection efficiency can be realized.

Next, an example of the manufacturing method of the air filter 3 of Embodiment 1 is demonstrated.

  Here, the manufacturing method of an air filter is demonstrated. As shown in FIG. 4, the manufacturing facility includes a transport unit 18 that transports the base material portion 15 in the horizontal direction, a nozzle 19 positioned above the transport unit 18, and a back surface that is a lower surface of the transport unit 18. And the electrode plate 20 positioned in the position.

  The nozzle 19 discharges fine fibers to the surface side which is the upper surface of the flat plate-like base material part 15 conveyed by the conveying means 18. The nozzle 19 is disposed in the conveyance direction of the base material portion 15, and the electrode plate 20 is substantially rectangular and is disposed to face the nozzle 19.

  In the manufacture of the filter medium part 10, first, the fine fiber is discharged from the nozzle 19 toward the base material part 15 while the flat plate-like base material part 15 is transported by the transport means 18. As shown in FIG. 5, a voltage of about +20 KV is applied to the nozzle 19, and a voltage of about −10 to 0 KV is gradually applied to the electrode plate 20 from the center to the end of the base member 15 in the direction perpendicular to the transport direction. Apply a voltage of. Due to this potential difference, the fine fibers discharged from the nozzle 19 adhere to the surface of the base material portion 15 to form the fine fiber layer 16. Here, when the voltage of about −10 KV is applied to the electrode plate 20 and when the voltage is 0 KV, the spread of the released fine fibers is different. When the voltage of about −10 KV is applied, the spread of the fine fibers is small, and when the voltage is about 0 KV. Therefore, when a voltage of about -10 KV is applied, the basis weight per unit area increases. In other words, when producing a central portion with a large basis weight, approximately -10 KV is applied, and when producing an end portion with a small basis weight, approximately 0 KV is applied, so that a smaller portion at the central portion than at both ends as shown in FIG. The fiber layer 16 is formed.

  In addition, in the case where the basis weight is increased radially at the center portion from the four end portions, in addition to applying the voltage stepwise from the center portion to the end portion of the base material portion 15 in the direction perpendicular to the transport direction, Application is performed while gradually changing the voltage along the conveying direction so that the absolute value of the applied voltage is maximized at the center of the filter medium portion 10 and minimized at both ends. Thereby, the fine fiber layer 16 in which the basis weight decreases radially from the central portion to the end portion is formed.

  As another method, the amount of fine fibers spun may be gradually changed along the conveying direction so as to increase at the center of the filter medium portion 10 and decrease at both ends. However, in this method, when the amount of spinning increases, dripping occurs, and productivity may deteriorate.

( Embodiment 2 )
Embodiment 2 of the humidification function air cleaning apparatus will be described. The same reference numerals are used for configurations having the same effects as those of the first embodiment , and detailed description thereof is omitted. Note that the content described below is only an example of implementation, but is not limited thereto.

FIG. 7 is a schematic cross-sectional view showing a main body configuration of an air cleaning device with a humidifying function according to Embodiment 2 of the present invention.

As shown in FIG. 7, for example, a humidifying unit 21 that humidifies the air blown by the blowing unit 2 is interposed in the air cleaning path in the first embodiment . That is, a substantially bowl-shaped humidifying tray 22 for storing water and a humidifying tank (not shown) for storing water used for humidification are arranged in the lower part of the main body case 1. Means 21 is erected, and the humidifying means 21 is disposed between the air filter 3 and the air blowing means 2.

  At this time, a part or all of the air sucked from the intake port 4 of the main body case 1 and passed through the air filter 3 passes through the humidifying means 21 and is humidified, and is discharged to the outside of the main body case 1 by the blower means 2. The Thus, the air purifier with a humidifying function of the present invention is capable of purifying the air sucked into the main body case 1 and humidifying the air.

  Here, as the humidifying means 21, for example, one end of a three-dimensional knitted fabric formed by bending a water-absorbing nonwoven fabric into a bellows shape or knitting at least partially using a water-resistant and water-absorbing synthetic fiber is humidified. The water stored in the tray 22 is submerged and absorbed, and air is passed through it to humidify by the action of water vaporization, and water-resistant synthetic fibers are knitted to produce water retention. A method in which the three-dimensional knitted fabric is periodically immersed in and taken out of water stored in the humidifying tray 22 by driving means such as an electric motor, and air is passed through the three-dimensional knitted fabric to humidify the water, or The disc-shaped rotating member is arranged so that its disc surface is substantially horizontal, and the disc is rotated about a direction perpendicular to the disc surface passing through the center of the disc, and stored in the humidifying tray 22 on the upper surface of the rotating member. A method of supplying humidified water, splitting the water into fine water droplets by centrifugal force due to rotation, passing the fine water droplets so that air is applied, and vaporizing the water droplets to humidify, the frequency in the ultrasonic region The ultrasonic vibrator that vibrates at is arranged so as to be submerged in the water stored in the humidifying tray 22, and the water is split into fine water droplets by the vibration of the ultrasonic vibrator, and air is applied to the fine water drops. The method of humidifying by evaporating water droplets and heating the water stored in the humidifying tray 22 with a heating element such as a heating wire or a ceramic heater and mixing the evaporated water vapor and air Etc.

  Thus, the use of the air filter of the present invention in the air cleaning device with a humidifying function provided with a humidifying means in the air cleaning path of the air cleaning device increases the air volume at the lower part of the filter near the humidifying filter, so that the humidifying capacity Can be improved.

  As described above, since the air filter of the present invention has low pressure loss and high dust collection efficiency, it is used as an air purification filter for removing allergens such as dust and pollen in an air purifier for home use or business use. be able to.

DESCRIPTION OF SYMBOLS 1 Main body case 2 Air blowing means 3 Air filter 4 Intake port 5 Exhaust port 6 Wind direction louver 7 Casing 8 Blade 9 Electric motor 10 Filter material part 11 Shape holding part 12 Frame part 13 Adhesive member 15 Base material part 16 Fine fiber layer 17 Protective layer 18 Conveyance Means 19 Nozzle 20 Electrode plate 21 Humidification means 22 Humidification tray

Claims (9)

A square plate-shaped filter medium part and a shape holding part for holding the filter medium part in a pleated shape are provided, and the filter medium part is formed on the upstream surface of the base material part and the air flow blown to the base material part. a fine fiber layer formed, is formed from a protective layer covering the fine fiber layer, in the central portion than at least opposing pair of end portions of the weight per unit area of said filtration portion of the fine fiber layer and a multi-home air filter, An air filter in which the basis weight of the fine fiber layer is increased at a central portion and decreased at an end portion along a pleated fold line direction . Air filter according to claim 1, basis weight of the fine fiber layer is characterized in that it is a 0.1~10.0g / ^{m 2.} Air filter according to any one of claims 1 to 2, characterized in that the fine fiber layer is composed of an average fiber diameter of 50-1000 nm. The base material portion and the protective layer are made of pulp fiber, resin fiber, carbon fiber and inorganic fiber, or at least one of them produced by a spunbond method, a dry or wet method, a meltblown method, a spunbond method, an airlaid method, or the like. The air filter according to any one of claims 1 to 3 , comprising a non-woven fabric. The air filter according to any one of claims 1 to 4 , wherein the protective layer includes a low melting point resin material. A body case with intake and exhaust ports;
Air blowing means provided in the main body case;
In the intake port of the main body case,
An air purifier equipped with the air filter according to any one of claims 1 to 5 . The air purifier with a humidification function which provided the humidification means in the air purification path | route of the air purifier of Claim 6 . 6. The method for producing an air filter according to claim 1, wherein the fine fiber layer is formed by an electrostatic spinning method using a polymer organic solvent solution. A square plate-shaped filter medium part and a shape holding part for holding the filter medium part in a pleated shape are provided, and the filter medium part is formed on the upstream surface of the base material part and the air flow blown to the base material part. This is a method for producing an air filter, which is formed from a provided fine fiber layer and a protective layer covering the fine fiber layer, and the basis weight of the fine fiber layer is larger at the center than at least one pair of opposite ends of the filter medium part. A nozzle that discharges fine fibers on the front surface side of the flat substrate portion is disposed in the conveying direction of the substrate portion, an electrode plate is disposed opposite to the back surface side, and the potential of the electrode plate is set to the substrate portion A pair of both ends where the basis weight of the fine fiber layer is at least opposite to each other by forming a fine fiber layer on the entire surface of the base material portion with the nozzle. An air filter manufacturing method for forming a fine fiber layer more in the center.

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