JPS6283016A - Filter medium - Google Patents

Abstract

PURPOSE:To compensate decreases in dust removing efficiency of electret fiber layers by increases in dust removing efficiency of non-electret fiber layers, by arranging the electret fiber layers upstream and the non-electret layers downstream. CONSTITUTION:20-60mum diameter fibers are used and packed in a packing density of 0.03-0.1cc/cc to form an electret fiber layer, thereby obtd. a filter layer having a low pressure loss and a high retention of dust remval. 20-60mu diameter fibers are used and packed in a packing density of 0.1-0.2cc/cc to form a non-electret fiber layer. A filter medium is formed by disposing the electret fiber layer upstream and the non-electret fiber layer downstream, thus to compensate the decrease in removing efficiency due to the decrease in static electricity of the former by the increase in removing efficiency due to the increase in dust loading of the latter and to maintain performance air filter for a long period.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a filter medium, and more particularly to a medium-performance air filter medium that is used in various air conditioning equipment and has low pressure loss and high dust retention properties. It is related to.

[Prior Art] Glass fiber filter paper made of ultrafine fibers, synthetic fiber nonwoven fabric, and the like are known as filter media for medium-performance air filters used in various air conditioning equipment. In all of these methods, filter media are made using raw materials with increased fiber optic density, so although the dust removal efficiency is high, the pressure loss of the filter media is extremely high, and most of the dust is captured near the surface of the filter media. It has been pointed out that since dust is collected, clogging tends to occur at an early stage, and the amount of dust retained is small.

[Invention 6\Problem to be solved] In order to solve the above problem, a filter medium with low pressure loss and a large dust retention capacity is required, and a so-called electric left am with a permanent charge is required.
Filter media is attracting attention. Although the pressure drop can be significantly reduced by lowering the fiber packing density in this filter medium, the dust removal efficiency is much higher than that of conventional glass fibrosis paper due to the strong electrostatic suction force of the electreft fibers. It is known that it has the property of indicating a value. However, even in this filter medium, there is a problem that as the powder IQS adhesion to the electret fibers progresses, the electrostatic force decreases and the removal efficiency decreases, and it is desired to realize a filter medium with even higher performance.

The present invention has been made in view of the above-mentioned problems, and it is an object of the present invention to provide an improved medium-performance air filter medium having low pressure loss and high dust retention performance.

[Means for Solving the Problems] The present invention that can solve the above problems is constructed by disposing an electret fiber layer on the upstream side and a non-electret fiber layer on the downstream side. Electret H & fiber layer has fiber packing density: 0.03~0, 10cc/cc,
The diameter of the constituent fibers is 20 to 60 ILm, while the valve electret fiber m layer has a 1a fiber packing density:
The gist is that it is configured with 0.10 to 0.20 cc/cc and a diameter of the structure 6takn: 10 to 30 m.

[Function] In the present invention, by arranging an electret fiber layer on the upstream side and a non-electret fiber layer on the downstream side, and forming a VI layer on both, the dust removal efficiency of the electret fiber layer due to dust load is improved. The aim is to compensate for the decrease in the dust removal efficiency of the non-electret fiber layer due to dust loading. Furthermore, in the present invention, by adopting a filter material configuration that satisfies the specified fiber packing density and fiber diameter, it is possible to obtain a striped material for an air filter that has a low pressure loss and a high dust holding amount, which has not been achieved in the past. That is.

The effects of the present invention will be further clarified by describing the structure of the present invention in detail below.

In the present invention, as described above, the fiber packing density of the electret m-lamination is specified to be 0.03 to 0.1 Occ/cc, and the diameter of the constituent m fibers is specified to be 20 to 60 pLm.

One reason for specifying the fiber density of the electret fiber layer to the above low density range is to achieve low pressure loss, and the other reason is to suppress the increase in pressure loss due to dust load in order to obtain a high dust retention amount. This is because it is effective for If the fiber packing density of the electret fiber layer exceeds 0.10 cc/cc, the increase in pressure loss due to dust load will increase, and the amount of dust retained will decrease, which is not preferable. However, the degree of increase in pressure loss due to dust loading depends on the distribution of the dust collecting plow blade in the thickness direction of the filter medium, and if dust is captured over a wide range in the thickness of the filter medium, the degree of increase in pressure loss will be small. , the degree of increase in pressure loss becomes larger when captured in a narrow range.

Also, the fiber packing density of the electric left fiber layer is 0603cc.
If it is less than /cc, the dust load on the non-electret fiber layer disposed on the downstream side becomes too large, and the dust retention amount of the entire own material decreases.For reasons such as 0 or more, the fiber filling of the electret M&M layer The density was set within the above specified range.

On the other hand, in the present invention, the reason why the diameter of the constituent fibers of the electret fiber layer is set to a specific range of 20 to 60 tm is to ensure a high dust retention amount that can be used as a medium-performance air filter material for air conditioning. be. However, if the diameter of the constituent fibers is less than 20 mm, the removal efficiency will exceed the removal efficiency of a neutral air filter for air conditioning, and on the contrary, it will be lower than the removal efficiency of a high-performance air filter. The removal efficiency is halfway, and a filter medium that meets the purpose of use cannot be realized. Also, if the diameter of the li and male exceeds 601 Lm, the removal efficiency of the electret fiber layer due to dust load will decrease significantly early, and it will be extremely low. down to the removal efficiency.

In the present invention, the fiber raw materials for the electret M & male layer include polypropylene, polyethylene, polyvinyl chloride,
Examples include polyvinylidene fluoride, and one or more of them are converted into an electret. Here, electretization means creating a state in which positive and negative charges remain even after the external electric field is removed. Methods of electrefting include thermal electret method, radio electret method, and magnetoelectret method. Various methods can be mentioned, such as the electroelectret method, the mechanoelectret method, and the electroelectret method.

On the other hand, Electret) tjl! The m-fiber packing density of the non-electleft fiber layer disposed on the downstream side of the layer is 0, lO ~ 0
．． 20cc/cc, the diameter of the constituent ta fibers is 10-30Bm
be specified. However, if the fiber packing density of the non-electret fiber mixture is less than 0.10 cc/cc or the diameter of component #a fibers exceeds 30 gm, the removal efficiency will decrease due to dust load in the upstream electret fiber layer. 4. If the non-electret fiber layer on the downstream side cannot compensate for this amount, the performance as a medium-performance air filter cannot be demonstrated, and if the fiber packing density of the non-electret fiber layer exceeds 0.20cc/cc. Alternatively, if the diameter of the constituent fibers is less than 10 #Lm, a problem arises in that the dust captured in the non-electret fiber layer is biased toward the upstream side, resulting in a decrease in the amount of dust held in the non-electret layer.

The fiber packing density of the non-electret fiber layer is 0610-0
．． 20cc/cc and the diameter of the constituent fibers is 10-30g
By being m, the upstream electret) m,!
It becomes possible to compensate for the decrease in removal efficiency due to the dust load on layer Ii with the non-electret fiber layer on the downstream side, and it is possible to suppress the increase in pressure loss due to the dust load in the non-electret fiber layer to a minimum. IM
In J, the size of the dust leaking through the upstream electret fiber layer is relatively large in the initial period when the electrostatic force of the electret im is strong and the dust load is low, and then as the dust load increases As the electrostatic force of the electret fiber layer becomes weaker, the particle size changes to smaller. Therefore, in the non-electret fiber layer,
First, dust with a relatively large particle size is captured on the upstream side of the non-electret fiber layer, and as the particle size becomes smaller, the capture area moves downstream, so uneven distribution of dust due to capture is less likely to occur.

Examples of the 1a material of the Mum layer (non-electret) include polyester, polyamide, polypropylene, polyethylene, rayon, pulp, etc. Examples of these M&fibers include spunpond nonwoven fabric, nonwoven fabric made by adhering and solidifying short fiber webs, and wet papermaking. etc.

Furthermore, in the present invention, it is important that the bipedal electret fiber layer and the non-electret fiber layer are in close contact with each other, and methods for this include needle punching treatment, point welding treatment, and others.

Examples include a suppression treatment method for generating entanglement of fibers between fiber layers.

In the present invention, the fiber packing density of the fiber layer is calculated by the following formula (1) by measuring the basis weight W (g/m2) of the fiber layer and the thickness T (c++) under no load using a microscope. It is a value.

[However, ρ: woven fiber density (g/cc)] The electret fiber layer and the non-electret fiber layer could not be used as materials for medium-performance air filters for air conditioning because their removal efficiency was insufficient when used alone. However, by employing the above-described configuration, the removal efficiency can be improved and a filter medium having a high dust holding amount can be realized. Such superiority of the present invention can only be realized by limiting the fiber packing density and the diameter of the structure am to the specific ranges mentioned above.

[Example] Example 1 A spunpond nonwoven fabric made of polypropylene ti fiber with a diameter of 40 lm was coated with a DC applied voltage of 20 KV between two electrodes.
Charging treatment by corona discharge was performed for 60 seconds under the condition of 0 s ■ to create an electret am layer with a fiber packing density of 0.06 cc/cc.

Next, various non-electret fiber layers were spot-welded to the above-mentioned electret fiber layer to create filter media of Example A and Comparative Examples A to D, and a dust collection performance test was conducted on each filter medium. Also, for comparison, glass TA for neutral plow air filters for air conditioning
Similar dust collection performance tests were conducted on the m-cancer paper (Comparative Example E), the m-single layer with only the electric left layer of Example A (Comparative Example F), and the m-single layer with only the non-electreft layer of Example A. . The results are summarized in Table ff11.

The test conditions are as follows. Removal efficiency is JIS l
Using li dust, digital dust meters (Model P-5H2, manufactured by Futada Kagaku) were installed on the upstream and downstream sides of the building materials, and the amount of scattered light was determined from the ratio.

Dust retention; -: is the value obtained by using JIS 15 type dust, determining the life as the end of the life when the pressure loss reaches 30 mmH2O, and weighing the amount of dust deposited on the cancer material on a balance at that time. The linear velocity of the test was 100 m/sec, and the size of the test material was 500 x 500 (11 layers).
belongs to.

Further, FIG. 1 shows changes in removal efficiency and pressure loss with respect to the amount of dust supplied in each test of Example A and Comparative Examples A to G.

From Table 1 and FIG. 1, the following 1t can be understood.

That is, compared to Comparative Example E, which is a medium-performance air filter material for air conditioning, Example A has almost the same initial removal efficiency, but exhibits a lower pressure and more than three times the amount of dust retained. In addition, it is predicted that the change in removal efficiency of Example A is due to the synergistic effect of Comparative Examples F and G, but the change in pressure loss shows behavior similar to Comparative Example F. .

This indicates that the pressure drop caused by the dust load of the polyester spunpond may be small (non-electret fiber layer).

Furthermore, if the fiber packing density and the diameter of the constituent fibers in the non-electret fiber layer are outside the specific range disclosed in the present invention, a decrease in removal efficiency or a decrease in the amount of dust retained will be observed.

Example 2 As a non-electret (m) multi-purpose house, #a fiber diameter 15 μm, packing density 0.15 cc/cc, basis weight Mk 85 g/
ls2 polyester fiber spunpond was used. Electret fiber! As the IR, various spun polypropylene fibers shown in Table 2 were used, which were subjected to a corona discharge treatment for 60 seconds at a DC applied voltage of 2QKV and an interelectrode pressure of j915m+w. Then, the above-mentioned two m multi-tenant buildings were stacked and subjected to needle punching treatment to form Example B and Comparative Example H.
- Various types of filter media were created.

The same dust collection performance test as in Example 1 was conducted on each of the various filter media obtained. The results are shown in Table 2 and Figure 2.

As is clear from Table 2 and FIG. 2, in the case of Example B, similar to Example A, the pressure loss was low [1 high powder m;
It is understood that it indicates a holding ox. Furthermore, if the fiber packing density of the electret fiber layer and the diameter of the constituent m fibers are out of the specified range of the present invention, the removal efficiency will decrease or the amount of dust retained will decrease.

[Effects] As described above, according to the present invention, by employing the above-described configuration, a filter medium that achieves improved removal efficiency and high dust retention can be realized. In addition, by using the filter medium according to the present invention in a medium-performance air filter for air conditioning, it is possible to extend the life of the air filter, thereby achieving a reduction in the frequency of replacing the air filter and the associated labor savings in maintenance. You can expect that. Furthermore, the filter medium according to the present invention is suitable for medium-performance air filters for air conditioning.

Not only that, it can be used in a wide range of fields such as industrial air filters, mask filters, etc.

[Brief explanation of drawings]

Claims (1)

[Claims] It is composed of an electret fiber layer on the upstream side and a non-electret fiber layer on the downstream side, and the electret fiber layer has a fiber packing density of 0.03 to 0.10.
cc/cc, the diameter of the constituent fibers: 20 to 60 μm, while the non-electret fiber layer has a fiber packing density of 0.10 to 0.20 cc/cc, and the diameter of the constituent fibers: 10 to 30 μm. A filter medium characterized by: