JP2006341220A - Parallel flow electret filter - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a parallel flow electret filter which is easily manufactured, and has high collection efficiency even when a pressure drop is low. <P>SOLUTION: This parallel flow electret filter is formed by laminating a plurality of sheets made into electrets. The sheet has protrusions which serve as spacers keeping spaces between the laminated sheets made into the electrets. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a parallel flow electret filter that removes dust and the like contained in air.

  As a conventional parallel flow type electret filter, a honeycomb structure in which corrugated sheets and flat sheets are stacked and fused or bonded, and the obtained units are stacked and bonded in multiple stages, for example, Patent Document 1 and the like. Is shown in In these conventional filters, as shown in FIG. 3, a hole formed by laminating corrugated sheet 6 and flat sheet 5 is used as an air passage, and electret processing is applied to either or both of these sheets. Therefore, the dust contained in the air flowing through the ventilation path is electrostatically adsorbed by the electric charge of these sheets.

  However, since the honeycomb structure of the conventional filter is manufactured in the same manner as the corrugated cardboard, the corrugated sheet has large pleats, and the interval when stacking the flat sheets in multiple stages is too large. Thus, there is a drawback that the electrostatic adsorption force does not sufficiently act on dust passing near the center of the ventilation path, and the collection efficiency is low.

  In the conventional filter, the corrugated sheet and the flat sheet are linearly bonded in parallel to the air flow direction, so that the contact area is large, and the sheet for electrostatically adsorbing dust is used. There was a drawback that the effective area ratio would decrease.

Furthermore, in the production of conventional filters, it is necessary to first produce a number of corrugated sheets, stack them in multiple stages and bond them to form a block, and finally cut them to the required filter size. Therefore, the process is complicated, and a large number of honeycomb-shaped holes appearing on the surface may be crushed in the process of cutting, which may result in high pressure loss when used as a filter. It was.
Japanese Patent No. 2856486

  An object of the present invention is to provide a parallel flow electret filter which is easy to manufacture and has a high collection efficiency even if the pressure loss is low.

Various studies have been made to solve the above problems, and it has been found that the above problems can be solved by providing a protrusion on the electret sheet to form a spacer, and the present invention has been completed.

That is, the parallel flow electret filter of the present invention has the following configuration.
(1) A parallel flow type air filter in which a plurality of electret sheets are laminated,
The electret sheet has a protruding portion, and the protruding portion serves as a spacer for maintaining a gap between the stacked electret sheets.
(2) The parallel flow electret filter according to (1), wherein the protrusions are arranged in a staggered manner on the electret sheet.
(3) The parallel flow electret filter according to (1), wherein the protrusions are randomly arranged on the electret sheet.
(4) The parallel flow electret filter according to any one of (1) to (3), wherein the protrusion is a resin applied to an electret sheet.
(5) The parallel flow type electret filter according to any one of the above (1) to (3), wherein the protruding portion is formed by raising a cut formed in an electret sheet.
(6) The parallel flow electret filter according to any one of (1) to (3), wherein the protrusion is an emboss formed on an electret sheet.

  The parallel flow type electret filter of the present invention is provided with a protrusion on the electret sheet, and the protrusions maintain the distance between the laminated electret sheets. Therefore, effective use of the filter medium while keeping the pressure loss low The collection efficiency can be increased by increasing the rate. In addition, manufacturing is easy and material costs can be reduced.

  The parallel flow type electret filter of the present invention is formed by laminating a plurality of electret sheets 2 as shown in FIG. 1, for example. The electret sheet 2 is provided with protrusions 3 intermittently with respect to the air flow direction, and the protrusions 3 serve as spacers for maintaining the distance between the stacked electret sheets 2. Plays. Here, as a material constituting the electret sheet 2 used in the present invention, it is not necessary to provide any restrictions as long as it is a sheet-like material that can be electret-processed, as well as a film, a spun bond, a chemical bond, a melt blow, etc. Nonwoven fabrics, woven fabrics and knitted fabrics can be used. The raw material of the sheet is not particularly limited, and synthetic resins such as polyethylene, polypropylene, polyester, polyfluoroethylene, polyfluorovinylidene, nylon, and acrylic can be suitably used. Corona charging, electric field charging, electron beam irradiation For example, electretization can be performed by a known means.

  It is preferable that the electret sheet 2 has a small thickness because the pressure loss when the filter is used can be reduced. On the other hand, if the thickness is too thin, the rigidity of the sheet itself is lowered, and bending due to wind pressure is caused. Problems such as occur. Therefore, the electret sheet 2 used in the present invention preferably has a thickness in the range of 0.06 to 1.5 mm. More preferably, an electret sheet having a thickness in the range of 0.10 to 1.0 mm is used from the viewpoint of low pressure loss and high collection efficiency of the filter.

  Further, in the present invention, as described above, the interval between the electret sheets 2 laminated by the protrusions 3 is kept, but the narrower the interval, the higher the collection efficiency when a filter is used. preferable. On the other hand, when the interval is too narrow, there is a problem that the ratio of the ventilation holes to the filter opening area is reduced, and the pressure loss is increased. Therefore, the interval between the electret sheets 2 of the parallel flow electret filter of the present invention is preferably in the range of 0.5 to 2.5 mm. More preferably, the interval between the electret sheets is in the range of 0.7 to 2.0 mm from the viewpoint of reducing the pressure loss of the filter and increasing the collection efficiency.

  And although the protrusion part 3 may be arrange | positioned regularly, the direction arrange | positioned at zigzag form or at random with respect to the air flow direction of an air filter is between the electret sheet | seats 2 laminated | stacked when it was set as the air filter. The air passing through the air tends to be turbulent, and dust in the air is likely to be electrostatically attracted to the electret sheet, which is preferable. In addition, the surface on which the protrusions 3 are provided may be one side or both sides of the electret sheet.

  It is preferable that the protrusions 3 be formed by continuous machining by a machine because manufacturing is easy and cost is advantageous. Therefore, in addition to bead processing such as hot melt resin, a method of bending up a notch put in a part of the electret sheet and starting up, embossing, or the like is preferably used. FIG. 2 shows an air filter 1 ′ in which a notch is cut into a part of the electret sheet 2 ′, and the notch is bent and raised to form a protrusion 3 ′.

  The smaller the size of the protrusion 3 is, the smaller the contact area when the electret sheet 2 is laminated, and the more effective area for electrostatically adsorbing dust in the air can be increased. The area of the electret sheet 2 is preferably 10% or less.

The parallel flow electret filter of the present invention can be manufactured, for example, as follows.
The sheet raw material drawn out from the unwinding machine is introduced into an electret forming apparatus such as a corona discharge machine and subjected to electret processing. The sheet coming out of the electret device is introduced as it is into a protrusion attaching device such as a hot melt bead processing machine, and protrusions are intermittently installed over the entire width of the sheet, and a large number of protrusions on the sheet It becomes a continuous electret sheet with a part. The sheet thus obtained is introduced into a cutting machine, and is cut in a fixed size with a certain feed amount to obtain an electret filter medium. By stacking a large number of the filter media, the parallel flow electret filter of the present invention can be obtained. When manufactured by such a method, since the electret filter medium is cut in a sheet form, the end face is sharp, and the inlet shape of the ventilation path when the electret sheets are laminated is not crushed. A filter with low pressure loss can be obtained.

Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to these examples as long as the gist thereof is not exceeded. The characteristic values used in the examples are measured by the following measuring method.
(1) Pressure loss and collection efficiency Measured by the method of JIS-B-9908 Format 1.
(2) QF value It calculated with the following formula | equation.

QF value (Pa ⁻¹ ) = − ln [{1- [collection efficiency (%)] / 100} / [pressure loss (Pa)]]
The QF value represents the collection efficiency per pressure loss, and it can be said that the higher the value, the higher the performance of the filter.

  (Example 1) A radius of 1. mm is provided so that a CD direction interval is 15 mm and an MD direction interval is 15 mm on one side of a sheet obtained by electretizing a polyester film having a width of 300 mm and a thickness of 0.3 mm by a corona discharge method. A 0 mm hemispherical polyolefin hot melt resin was applied to form protrusions (see FIG. 4). The electret sheets cut in a fixed size with a feed amount of 30 mm were stacked in multiple stages so as to have a height of 300 mm and incorporated into an aluminum casing to obtain a parallel flow electret filter of the present invention. The results of measuring the characteristic values of the obtained filter are shown in Table 1.

(Example 2) Polyester melt blown nonwoven fabric (weight per unit 30 g / m ² thickness 0.33 mm) electret-processed by the corona discharge method is a polyester short fiber resin processed nonwoven fabric (weight per unit 37 g / m ² , thickness 0.34 mm). A filter medium (thickness 0.7 mm) bonded with a urethane adhesive (coating amount 4 g / m ² ) is slit to a width of 300 mm, and isosceles triangular with a base of 2.0 mm and a height of 1.5 mm Protrusions whose notches were raised to 90 degrees were arranged in a staggered manner in the air flow direction so that the CD direction interval was 20 mm and the MD direction interval was 10 mm (see FIG. 5). The electret sheets cut in a fixed size with a feed amount of 30 mm were stacked in multiple stages so as to have a height of 300 mm and incorporated into an aluminum casing to obtain a parallel flow electret filter of the present invention. Table 1 shows the measurement results of the characteristic values of the obtained filter.

(Comparative example 1) Corrugated sheet made of polypropylene melt blown nonwoven fabric (weight per unit: 40 g / m ² , thickness 0.40 mm) electret-processed by corona discharge method and corrugated sheet with a peak height of 3.0 mm, from the same melt blown nonwoven fabric The resulting flat sheet was laminated and bonded in multiple stages to obtain a honeycomb block. This was cut into a size of 300 mm in width, 300 mm in height, and 30 mm in depth, and incorporated in an aluminum casing to obtain a parallel flow electret filter. Table 1 shows the measurement results of the characteristic values of the obtained filter.

  The parallel flow electret filter of the present invention can be suitably used, for example, as a filter for an air purifier or a room air conditioner for which an inexpensive filter is preferred.

It is a principal part expansion perspective view of the parallel flow type electret filter which shows one Embodiment of this invention. It is a principal part expansion perspective view of the parallel flow type electret filter which shows other embodiment of this invention. It is a perspective view of the conventional parallel flow type filter. FIG. 3 is a schematic diagram of a protrusion arrangement of an electret sheet used in Example 1. It is the protrusion part arrangement schematic of the electret sheet | seat used in Example 2. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1, 1 ': Air filter 2, 2': Electret sheet 3, 3 ': Protrusion part 4: Air filter 5: Flat sheet 6: Corrugated sheet 7: Protrusion part by hemispheric polyolefin hot-melt resin 8: Protrusions formed by rising an isosceles triangle cut by 90 degrees

Claims (6)

  A parallel flow type air filter in which a plurality of electret sheets are laminated, wherein the electret sheet has a protrusion, and the protrusion serves as a spacer for maintaining a gap between the laminated electret sheets. A parallel-flow electret filter characterized by   The parallel flow type electret filter according to claim 1, wherein the protrusions are arranged in a staggered manner on the electret sheet.   The parallel flow electret filter according to claim 1, wherein the protrusions are randomly arranged on the electret sheet.   The parallel flow electret filter according to any one of claims 1 to 3, wherein the protrusion is a resin applied to an electret sheet.   The parallel flow type electret filter according to any one of claims 1 to 3, wherein the projecting portion is formed by raising a cut made in an electret sheet.   The parallel flow type electret filter according to any one of claims 1 to 3, wherein the protrusion is an emboss formed on an electret sheet.

Images