JPH06254433A - Air filter - Google Patents

Abstract

PURPOSE:To reduce the load of a blower motor by applying voltage across a plurality of conductive porous layers laminated by interposing permeable non-conductive layers in an air filter for an air cleaner for air conditioning or the like. CONSTITUTION:Two conductive porous layers 1 or more are laminated by interposing air permeable non-conductive layers 2 composed of a non-woven cloth or the like used as a filter medium to constitute a filter. For the conductive porous layers 2, wet and dry non-woven cloth containing conductive fibers or the like is used mostly, although not particularly specified. A non-woven cloth sheet into which metallic fibers are contained is used for the purpose. Power source terminals 5 connected with cathodes or anodes of a power source are disposed respectively on the conductive porous layers 1, 1, connected with the power source and voltage is applied among the conductive porous layers 1, 1. Also folding work can be carried out to increase the filter area.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an air filter used in household air purifiers, semiconductor manufacturing, pharmaceutical manufacturing, foods, hospitals and the like.

[0002]

2. Description of the Related Art An electrostatic precipitator, a mechanical filter or the like is used to supplement suspended particles having a particle size of 5 microns or less. The electrostatic precipitator is a method in which an electric field is applied to the particles to collect the particles on the collecting electrode plate by an electric field, whereas the mechanical filter collects the particles by a sieving effect and an adhesion effect. Conventionally, a filter material using micro glass fiber is generally used for a medium-performance and high-performance air filter. Further, in recent years, a filter called an electret filter made of a fiber in which an organic fiber is permanently charged has been used. Details of the air filter and the removal of airborne particles are described in detail in "Clean Room Handbook" (edited by Japan Air Cleaning Association, published by Ohm Co., Ltd., January 1989).

As a filter for applying a voltage to a conductive layer, an air purifying device using a conductive sponge has been disclosed in Japanese Patent Laid-Open No. 174954/1986, and Japanese Laid-Open Patent Publication No. Hei 2 (1999) -31945.
Japanese Patent No. 253867 discloses a filter in which a conductive filter and a dielectric filter are combined.

[0004]

Since an air filter using micro glass fiber has high collection efficiency and flame retardancy, it is widely used for industrial, industrial and public facilities. Although it is used, it requires a large blower because the pressure loss is high and the wind load is large.
Therefore, there is a problem that not only the power cost is high but also the noise is large.

The electret filter using the electret fiber has been attracting attention in recent years because it has a lower pressure loss than the filter using the micro glass fiber and a low load of air flow, but its filtration resistance is still satisfactory. Not low. Further, liquid fine particles such as tobacco tar are inevitably accompanied by a decrease in the collection efficiency due to the coating of the fiber surface with the particles.

Further, Japanese Patent Laid-Open No. 61-174954,
The air purifying device and filter disclosed in Japanese Patent Laid-Open No. 2-253867 basically charge fine particles in the air by corona discharge and adsorb and collect them by electrostatic force action, which requires a high voltage of 4 to 10 kV. There was a problem with the generator and handling.

The present invention provides an air filter capable of reducing the load of the blower motor, which is a drawback of the above-described filter and has an extremely low load of blown air.

[0008]

Means for Solving the Problems As a result of intensive studies to solve the above-mentioned problems, the present inventors have found that a space between filter materials made of a conductive porous material laminated with a breathable non-conductive layer interposed therebetween. The present invention has been completed by finding that high filtration efficiency can be obtained with a filter material having a very low pressure loss by applying a relatively low voltage to the filter.

That is, the present invention comprises at least two conductive porous layers laminated with a breathable non-conductive layer interposed and a means for applying a voltage between the conductive porous layers. It is a featured air filter.

The conductive porous material layer is not particularly limited and may be any as long as it has conductivity as a sheet, but it contains wet and dry non-woven fabrics containing conductive fibers and conductive fibers. Examples thereof include knitted fabrics, woven fabrics, nets, meshes, and knitted fabrics, woven fabrics, nets, meshes and non-woven fabrics made of non-conductive fibers, which are provided with a conductive coating.

More specifically, for example, a mesh made of metal fibers or wires, a non-woven sheet made by mixing metal fibers or metal-coated fibers, a knitted cloth, a woven cloth, a mesh, and a non-woven cloth of organic fibers or inorganic fibers. A fiber structure having a metal coating on it, a foam metal, or the like can be used. Among these, the metal-plated nonwoven fabric is most preferably used because it has high conductivity and is lightweight.

Examples of the metal-plated nonwoven fabric include:
Inorganic fiber such as glass fiber, organic fiber such as acrylic fiber, polyester fiber, vinylon fiber, semi-synthetic fiber such as acetate fiber and triacetate fiber, recycled fiber such as rayon fiber, natural fiber such as cotton and wood pulp, etc. Alternatively, dry non-woven fabric or wet non-woven fabric prepared by mixing two or more kinds of copper with copper on the fiber surface of non-woven fabric by a method such as electroless plating
The thing which provided the coating of metals, such as nickel and silver, is mentioned.

A typical example of the breathable non-conductive layer is a porous material capable of ensuring insulation between conductive porous bodies. For example, various non-woven fabrics used for filter materials and other materials, paper and foam. Materials such as plastic can be preferably used. When higher collection efficiency is required, it is preferable to use a micro glass fiber nonwoven fabric.

As a means for applying a voltage between the conductive porous layers, for example, a power source terminal for connecting a cathode or an anode of a power source to the conductive porous layer may be provided by a conventional method.

The voltage to be applied is not particularly limited, but is preferably in the range of 100v to 1.0kv. 100
If it is less than v, the effect of improving the dust collection efficiency by applying a voltage is small, and if it exceeds 1.0 kv, there is a risk of destruction of the non-conductive porous layer due to discharge, which is not preferable.

As the constitution of the laminated filter filter material, for example, as shown in FIG. 1, one composed of two conductive porous material layers and a non-conductive porous material layer provided therebetween, and as shown in FIG.
An example is one composed of a conductive porous body layer and a non-conductive porous body layer having a number of layers or more.

Further, it is also possible and preferable to use such a laminated body by folding it like a conventional air filter as shown in FIG. 3 to increase the filtration area.

The conductive porous layer and the air-permeable non-conductive layer may be simply laminated, or may be integrally joined with a binder or the like. Further, for example, only the surface layer of the non-conductive nonwoven fabric is electrically conductive. You may use what formed the electroconductive layer by performing the chemical conversion treatment.

[0019]

The air filter of the present invention has a very high trapping efficiency due to the action of the electric field, although the pressure loss is low.

[0020]

The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples.

The pressure loss and dust collection efficiency in Examples and Comparative Examples were measured by the following methods. Pressure loss: The ventilation resistance when air was passed through the laminated filter materials at a flow rate of 5.3 cm / sec was determined by a water column manometer. Dust collection efficiency: Dioctyl phthalate particles having an average particle size of 0.3 μm are generated, and air containing these particles is passed through a laminated filter material at a flow rate of 5.3 cm / sec, and air is sampled before and after the filter material. The number of particles therein was measured using a light scattering type particle counter (KC-11, manufactured by Rion Co., Ltd.) and calculated using the following formula.

[Equation 1]

COMPARATIVE EXAMPLE 1 Table 1 shows the pressure loss and collection efficiency of a conventional medium-performance filter material for air filters using micro glass fiber as Comparative Example 1.

Comparative Example 2 and Examples 1 to 3 One glass fiber nonwoven fabric (glass fiber diameter 9 μm, basis weight 80 g / m ² ) was used as the breathable non-conductive layer, and one 35 mesh stainless mesh was used as the conductive porous layer. , A glass fiber non-woven fabric as a breathable non-conductive layer (glass fiber diameter 9 μm, basis weight 75
g / m ² ) 2 pieces, 35 mesh stainless mesh 1 piece as conductive porous body layer, glass fiber nonwoven fabric (glass fiber diameter 9 μm, basis weight 75 g / m ² ) as breathable non-conductive layer 1
Laminate the sheets one by one, and place 0 between the stainless meshes.
The voltages of v, 250v, 500v, and 1kv were applied to obtain Comparative Example 2, Example 1, Example 2, and Example 3, respectively. Table 1 shows each pressure loss and collection efficiency.

From the examples it can be seen that by applying a voltage a very high collection efficiency is achieved without an increase in pressure loss. Further, when comparing Comparative Example 1 and Example 3 which are medium performance filters having substantially the same collection efficiency, it is possible to significantly improve the pressure loss to 1/6 or less with substantially the same collection efficiency. Recognize. Further, it can be seen that the collection efficiency is improved by increasing the applied voltage.

[0025]

[Table 1]

Comparative Example 3 and Examples 4 to 6 The electroconductive porous layer of the laminate of Example 1 was applied to a glass fiber non-woven fabric (glass fiber diameter 9 μm, basis weight 75 g / m ² ) with electroless thickness of 0.15 μm. Laminates having the same configuration as in Example 1 except that a copper-plated nonwoven fabric was used, and voltages of 0 v, 500 v, and 1 kv were applied between the conductive porous layers, respectively, and Comparative Example 3, Example 4, and Example 5 respectively. And Table 2 shows each pressure loss and collection efficiency.

[0027]

[Table 2]

Comparative Example 4 and Examples 6 and 7 The conductive porous layer of the laminate of Example 1 was replaced with a nickel foam (Sumitomo Electric Co., Celmet, product number # 7, thickness 1.6 m).
m) was used and laminated with the same configuration as in Example 1, and voltages of 0 v, 500 v, and 1 kv were applied between the conductive porous layers, to form Comparative Example 4, Example 6, and Example 7, respectively. . Table 3 shows each pressure loss and collection efficiency.

Comparative Example 5 and Examples 8 and 9 The conductive porous layer of the laminate of Example 1 was mixed with 80 parts of acrylic fiber (fineness 3 denier, fiber length 5 mm) and 20 parts of polyester heat-fusible fiber. Wet papermaking basis weight 80 g / m ²
The same non-woven fabric as in Example 1 was used except that the non-woven fabric was coated with nickel at 20 g / m ^{2 by} electroless plating.
Voltages of v, 500 v, and 1 kv were applied to obtain Comparative Example 5, Example 8, and Example 9, respectively. Table 3 shows each pressure loss and collection efficiency.

Comparative Example 6 and Example 10 A glass fiber nonwoven fabric (glass fiber diameter 9 μm, basis weight 75 g / m ² ) was used as the breathable non-conductive layer, and a glass fiber nonwoven fabric (glass fiber diameter 9 μm, basis weight) was used as the conductive porous layer. Amount 75g /
m ²⁾ in a plating thickness 0.15μm electroless copper plated nonwoven, between each of five total breathability nefarious conductive layer of the sheet, to insert stacked four conductive porous layer, breathable cruel 0 between the conductive porous layers adjacent to each other via the conductive layer
A voltage of v and a voltage of 500 v were applied to Comparative Example 6 and Example 10, respectively. Table 3 shows each pressure loss and collection efficiency.

[0031]

[Table 3]

Comparative Example 7 As a comparative example 7, a commercially available filter material for semi-high performance air filters using micro glass fibers is shown in Table 4 for its pressure loss and collection efficiency.

Comparative Example 8 and Example 11 As Example 8 except that the non-conductive porous layer between the conductive porous layers of Example 8 was replaced with a medium performance air filter filter material using commercially available micro glass fiber. Comparative examples 8 and 11 were prepared by stacking layers with the same structure and applying voltages of 0 v and 1 kv between the conductive porous layers. Table 4 shows each pressure loss and collection efficiency.

[0034]

[Table 4]

In Example 11, as compared with Comparative Example 7 which is a semi-high performance air filter filter material having substantially the same collection efficiency, the pressure loss is about 1/3 with substantially the same collection efficiency, and the low pressure loss. It can be seen that it is a highly efficient air filter.

[0036]

The air filter of the present invention is an air filter with dramatically lower pressure loss than the conventional air filter. By using the air filter of the present invention, the load of the blower fan motor is reduced and the power consumption is reduced. It is an excellent air filter that has the advantages that not only the volume and noise can be reduced, but also the filter area can be reduced to an ultra-thin and lightweight filter unit. is there.

[Brief description of drawings]

FIG. 1 is a diagram showing a cross section of a configuration example of a filter of the present invention.

FIG. 2 is a diagram showing a cross section of a configuration example of a filter of the present invention.

FIG. 3 is a diagram showing an example of a cross section of a fold unit of a filter of the present invention.

[Explanation of symbols]

 1 conductive porous layer 2 non-conductive porous layer 3 air flow direction 4 frame 5 power supply terminal

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Takeshi Yamazaki 3-4-2 Marunouchi, Chiyoda-ku, Tokyo Sanryo Paper Co., Ltd. (72) Kenji Hyodo 3-4-2, Marunouchi, Chiyoda-ku, Tokyo Sanryo Paper Co., Ltd. (72) Inventor Akira Fujishima, 710 Nakamaruko, Nakahara-ku, Kawasaki-shi, Kanagawa 5 (72) Inventor Kazuhito Hashimoto, 2000, Kosugaya-cho, Sakae-ku, Yokohama-shi, Kanagawa 2 Minami-Kosugaya Houses 2 506 (72) ) Inventor Tamio Saito 22 from 8-12 Kawabemachi, Ome City, Tokyo

Claims (3)

[Claims] 1. An air filter comprising at least two conductive porous layers laminated with a breathable non-conductive layer interposed therebetween, and means for applying a voltage between the conductive porous layers. 2. The air filter according to claim 1, wherein the conductive porous layer is a metal-plated nonwoven fabric. 3. The air filter according to claim 1, wherein the breathable non-conductive layer is a micro glass fiber nonwoven fabric.