JPH03238011A - Air purifying filter - Google Patents

Abstract

PURPOSE:To remove hydrogen sulfide or acetaldehyde by laminating an electret filter, planar sheets and corrugated sheets to form a filter and adding activated carbon to one sheets and providing deodorizing function to the other sheets. CONSTITUTION:An electret filter, planar sheets 1 and corrugated sheets 2, 3 are combined and activated carbon is added to one sheets 1 and, for example, malic acid and ferrous sulfate are applied to the other sheets 2, 3 to provide deodorizing function due to chemical reaction or catalytic action. As a result, pressure loss is reduced and suspended dust and malodorous components such as hydrogen sulfide, ammonia or acetaldehyde can be removed.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is used as a filter for an air purifier to remove dust and bad odors floating in the air, and has particularly low pressure loss. Moreover, it relates to an air purifying filter that has a high cleaning effect.

[Conventional technology]

Conventionally, electrostatic air cleaners or electrostatic precipitators have been used to remove airborne dust. These charge dust particles by means of a corona discharge, and collect and remove the dust particles using oppositely charged electrodes or filters. However, in order to charge dust particles by corona discharge, a high voltage of several kilovolts or tens of kilovolts is required, which is not only dangerous in handling, but also poses a risk of fire. For this reason, there is a strong demand for dust collectors that do not require high voltage, and various filters that do not rely on electrostatic effects have been proposed. It was inevitable that a filter with extremely high pressure loss would be required because the following dust particles also needed to be collected. Therefore,
With this method, it is extremely difficult to efficiently remove dust particles with low pressure loss.

Additionally, in order to remove bad odors, activated carbon packed beds have been used in conventional filters, but because the adsorption rate of bad smelling substances is slow, activated carbon with smaller particle size or thicker packed layers must be used. was used. However, the pressure loss was large and fan noise became a problem when trying to ensure sufficient air volume. Japanese Unexamined Patent Publication No. 58-175560 discloses a low pressure loss type air purifying filter that combines an electret filter and a honeycomb sheet containing activated carbon. However, although activated carbon has an excellent ability to adsorb and remove a wide variety of malodorous substances, it has insufficient adsorption ability for ammonia or acetaldehyde, which is the main component of indoor cigarette odor.

[Problem to be solved by the invention]

As a filter for indoor or car air purifiers, it is necessary to remove suspended dust and bad odors, and to have low pressure loss.
Particularly important is the removal of acetaldehyde, which is the main component of cigarette odor, as well as hydrogen sulfide and ammonia, which cannot be sufficiently removed with activated carbon. Furthermore, in order to reduce the noise of the air circulation fan, it is necessary to use a filter with extremely low pressure loss.

[Means for solving problems]

The present inventors focused on the fact that among suspended dust, particles with a diameter of 1 μm or less, such as cigarette smoke, which are difficult to remove with ordinary filters, have a positive charge, and found that high voltage is necessary. Instead, we adopted an electret filter that is easy to handle and highly safe. Furthermore, as activated carbon for removing bad odors, impregnated activated carbon, which is usually impregnated with various chemicals to the activated carbon to remove malodorous components that cannot be removed sufficiently with activated carbon alone, is effective. be. However, with this method, the adsorption performance of activated carbon may be reduced depending on the chemicals used, and if chemicals that react with each other, such as acids and bases, are impregnated on the same activated carbon, they will react with each other and become less effective. may be reduced.

Therefore, the present inventors have discovered that it is effective to use an activated carbon sheet and a sheet to which a deodorizing agent is attached by chemical reaction or catalytic action in combination, and that the pressure loss is also extremely low, and have arrived at the present invention.

That is, it is a combination of an electret filter and a filter made by laminating a planar sheet and a corrugated sheet, one of which contains activated carbon and the other sheet has a deodorizing function by chemical reaction or catalytic action. , an air purification filter.

The present invention will be explained in detail below.

The air purification filter of the present invention incorporates an electret filter. The material of this filter is electrically polarized, in other words, it always has a constant static charge. Therefore, since ultrafine particles with a diameter of 1 μm or less, such as cigarette smoke, usually have a positive charge,
It is attracted to the negatively charged part of the electret filter.

Therefore, it can be removed efficiently with low pressure loss. Removal of such ultrafine particles by ordinary filtration is quite difficult and requires a high pressure loss. Electret filters are usually made of a material that becomes a dielectric when polarized through electret treatment, such as polymers such as polyethylene, polypropylene, polyester, and polyvinyl fluoride. Various methods are known to permanently polarize the polarization, but it is usually achieved by sandwiching a dielectric between electrode plates, raising the temperature to near its softening point, and slowly cooling it to room temperature while applying a high DC voltage. It will be done. Moreover, since this polarized state is maintained for several years, it has a function of removing ultrafine particles for a long period of time. Furthermore, since there is no need to apply a high voltage during use, there is no risk of handling or fire, and the safety is high.

Next, the deodorizing filter of the present invention has a structure in which planar and corrugated sheets are laminated.

This is a typical cardboard structure, but if air is allowed to pass through the cylindrical body, which is a segment of such cardboard, a filter with extremely low pressure loss can be obtained, which is suitable for the purpose of this application. It is. The structure of the deodorizing filter of the present invention is adopted in order to extremely reduce pressure loss. Therefore, in the claims of the present invention, "flat sheets and corrugated sheets are laminated"
The structure includes not only the typical cardboard structure, but also cases where the sheet is corrugated to the extent that it consists of a flat sheet, or where the cross section of the corrugated sheet is considerably deformed into a triangular, square, or other shape. This also includes cases where the cross section of the filter has a honeycomb shape in a broad sense.

One of the "flat and corrugated sheets" of the present invention must contain activated carbon, and the other sheet must have a deodorizing function through chemical reaction or catalytic action. Therefore, the present invention requires a significant reduction in the pressure loss of the filter. Ordinary granular activated carbon cannot be used because a sufficient deodorizing function cannot be imparted unless the packed bed is thick enough, and if the packed bed is thick, the pressure loss increases. In order to increase the adsorption rate, it is necessary to use activated carbon with a large specific surface area and a large macroscopic particle surface area, that is, fine particles. Therefore, by inserting activated carbon fine particles into the sheet or applying the fine particles to the surface in an ink-like form, it is possible to provide high malodor removal ability with low pressure loss. The above-mentioned functions can be imparted to the filter by using activated carbon fine particles or particles having a large macroscopic surface area, such as fibers. Further, the method of attachment is not limited to the above-mentioned plowing or coating, but any method may be used as long as the activated carbon or the like can be contained in the sheet.

Activated carbon is a unique material that has extremely excellent adsorption properties as a non-polar adsorbent, and shows high adsorption properties for almost all gaseous substances, but exceptionally low adsorption properties for sulfur compounds and aldehydes. The air in living spaces such as offices, cars, and homes usually has a strong odor of tobacco, and its composition includes acetaldehyde, ammonia, lower amines, hydrocarbons, hydrogen sulfide, etc. Note that the cigarette odor here refers to the odor of gas generated when smoking. In particular, activated carbon has a high proportion of ammonia, which is a weak point in adsorption, and also has a relatively large amount of lower aliphatic aldehydes, so it is difficult to remove the odor using ordinary activated carbon alone.

As substances that have the function of removing these malodorous substances through chemical reactions, effective substances that react with alkaline gas include phosphoric acid, sulfuric acid, nitric acid, malic acid, citric acid, and ascorbic acid.

In addition, copper phosphate, copper iodide, ferrous phosphate,
Examples include ferrous sulfate, zinc oxide, and zinc hydroxide. Therefore,
Deodorization can be achieved by using a sheet attached with these substances.

Furthermore, palladium chloride and silver chloride have a catalytic action and decompose odor components, and are effective in decomposing and removing ozone generated by electronic copying machines, which has recently become a particular problem. These can also be used attached to a sheet, and when used in combination with an activated carbon-containing sheet, a high synergistic deodorizing effect can be achieved.

It is also possible to use many substances that have chemical reactions or catalytic effects, and in addition to attaching them to the same sheet,
It can also be attached in multiple sheets. In this case, these sheets do not necessarily need to be used alternately, but may be used in combination as appropriate depending on the content of malodorous substances in the air (Fig. 3). Further, the ratio of the areas of the planar sheet and the corrugated sheet can also be appropriately set by changing the shape of the corrugations or the deformation of the planar sheet. Furthermore, the laminated layers include not only two-dimensional stacking but also a wide range of configurations such as, for example, a case in which cardboard is rolled up into a cylindrical shape.

[Action/Effect]

The present invention uses an electret filter to efficiently remove suspended dust in the air with a diameter of 1 μm or less with low pressure loss, and is therefore effective in removing cigarette smoke and does not require high voltage unlike conventional methods, making it easy to handle. Easy and highly safe. In addition, in order to remove malodorous substances that cannot be removed sufficiently with activated carbon alone, it has a sufficient deodorizing function because it is used in combination with a sheet containing a reactive substance and a substance that has the function of decomposing and removing by catalytic action.

Furthermore, these filters have a cardboard-type structure with extremely low pressure loss, allowing a large amount of air to pass through them in a short period of time, and the fan noise is also low. Therefore, it is extremely effective as an air purifying filter for offices, car interiors, and homes.

〔Example〕

The present invention will be explained in more detail below with reference to Examples, but the present invention is not limited thereto in any way.

Example 1 An air purifier was created by combining a molded body made by alternately corrugating and laminating a flat sheet with malic acid and ferrous sulfate coated on a nonwoven fabric and a corrugated sheet with activated carbon attached, in combination with an electret filter. I made it and measured its performance.

An electret filter was installed on the upstream side of the wind, and a deodorizing filter was installed on the downstream side. In addition, as a comparative example, examples of using a filter that was not electretted and a deodorizing filter were described.

(a) Cardboard laminated filter material with only sheet activated carbon Material: Coconut shell activated carbon, 90% SOO mesh pass.

Average particle size: approximately 20μm Paper quality: Polyester + polyethylene nonwoven fabric, date 2
0 glrd, 2 parts of 3% carboxymethyl cellulose solution (hereinafter referred to as CMC) as an adhesive and 3 parts of 4596 acrylonitrile butadiene latex, and powdered activated carbon was dispersed and applied. Activated carbon date i o o g7nr, thickness 0.65mm.

Step processing: pitch 4.2mm, height 2. Cut 5mm cardboard pieces into 20mm lengths and stack them. Pressure loss 1.
10mmH2O0 (b) A deodorizing sheet created by a chemical reaction with the activated carbon sheet is an alternately laminated adsorbent with l=1.The activated carbon sheet is made of the same material and paper-like material as in (a).The deodorizing sheet created by a chemical reaction is as follows. Material: Malic acid + ferrous sulfate (weight ratio 7:3) Paper quality: Polyester + polyethylene nonwoven fabric, basis weight 20g/
Ceramic powder is dispersed and applied to a suspension of nf with 2 parts of 3% CMC and 3 parts of 45% acrylonitrile butadiene latex as an adhesive, and a chemical reactant is attached. Anti=11 6th agent basis weight 25g/rrr, thickness 0.65non.

Step processing: pitch 4.2m+, height 2. Cut 5mm pieces of cardboard (corrugated product from A for the corrugated plate part, and use the corresponding paper-like material for the flat plate part) to 2° length marks and laminate them. Pressure drop: 1.10 ffiInH200 (C) 25 g of malic acid + ferrous sulfate (7:3) was added to a cardboard laminated filter (a) in which a chemical reactant was impregnated with sheet-like activated carbon.
ffl attached.

(d) Electret filter material Material: PP fiber thickness: 5mm Date: 200g/rrf' Pressure loss: 6 lungs H20 Collection rate = 98% (e) Filter material without electret processing Material: PP fiber thickness: 5mm 2- Weight: 200g/n'f Pressure loss: 6mmH2O In both cases, the wind speed is 0.5m/sec, and the dust collection rate is the collection efficiency for particles of 0.5μm to 1.0μm in atmospheric dust. .

The test results are shown in Table 1 below.

Table 1 Dust collection rate Next, we will compare the odor component removal performance.

Machine smoking 5 bottles of Mild Seven in a 1m acrylic cubic box with an air volume of 1.5m? It was deodorized by circulating 3 degrees per minute. The gas concentration before and after was measured using a gas detection tube and a hydrocarbon meter, and the removal rate was calculated.

Filter dimensions are 100 W x 300 L x 2
0 t mm.

As shown in Table 2 below, it can be seen that the present invention is also excellent in deodorizing properties.

Margin below Table 2 Odor gas removal rate (%) Margin below 16 5

[Brief explanation of drawings]

1.3 are perspective views showing one embodiment of the present invention, and FIG. 2 is a sectional view showing another embodiment of the present invention. 1----Sheet containing activated carbon 2--Sheet that has a deodorizing function by chemical reaction or catalytic action 3--Sheet that has a deodorizing function by chemical reaction or catalytic action and has different ingredients from 2.

Claims (1)

[Claims] This air purifying filter is a combination of an electret filter and a layered filter consisting of a flat sheet and a corrugated sheet. One sheet contains activated carbon, and the other sheet has a deodorizing function through chemical reaction or catalytic action.