JPS5951323B2 - electret filter - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an electret filter used for removing particulates mixed in gas or liquid for purposes such as air purification, dust collection, and dust removal.

Electric dust eliminators and electrostatic filters are already in use as devices to purify the air by removing cigarette smoke and dust from the air, but these devices not only have high equipment costs but also lack effective performance. The disadvantage is that it has a short life span.

In order to eliminate such drawbacks of conventional devices, the present invention aims to provide an electret filter that has excellent dust collection performance and a long life by utilizing an electret polymer film as a filter.

The present invention involves continuously bending or folding an electret-formed polymer film to form pleats on the entire surface of the film to give it thickness and create a large number of continuous voids. This material constitutes the electret filter.

Further, according to the present invention, the main material of the electret filter is a laminate product constructed by stacking pleated electret films in the thickness direction and bonding or fusing the tips of the pleats.

The polymeric material used in the present invention may be any material that can be formed into a film by melt molding, casting, cutting, etc., such as thermoplastic citrus resins such as polyolefin resins, polyester resins, and polyamide resins. , phenolic resin, formaldehyde beet, urea-formaldehyde beet, melamine-formaldehyde resin, and other thermosetting resins are used.

Among these, preferred are polyolefin resins such as polyethylene, polypropylene, poly-4-methyl-1-pentene, and polystyrene, which have excellent electret performance, as well as polyester resins such as polyethylene terephthalate and polycarbonate resins, which are unsaturated carboxylic acid resins. and those obtained by blending or graft polymerization with derivatives thereof.

Furthermore, conventionally known stabilizers such as antioxidants and heat-resistant stabilizers may be added to these sugar beets as necessary.

The polymer film is usually made to have a thickness of about 3 μm to 3 mm, and is stretched in one or two directions as necessary.

This polymer film may be foamed or porous, may be crosslinked, or may be a nonwoven film, and two or more films may be laminated.

The polymer film is electretized by various known methods such as thermal electretization, electroelectret method, radioelectret method, mechanoelectret method, magnet electret method, and photoelectret method.

This electret I-conversion treatment is performed at the same time as the film forming, or before or after the film forming, depending on the purpose.

Next, embodiments of the present invention will be described with reference to the drawings.

The first embodiment shown in FIG.
is continuously bent into a chevron shape to form folds 2 on the entire surface of the film to increase its thickness and create a large number of continuous voids 3 of triangular tubes.
The pleated Electref 1 to film 1 are stacked in the thickness direction with a flat ordinary film 4 interposed therebetween, and flat ordinary films 4 are attached to the top and bottom, and the ends of the pleats are placed on the flat film 4. The pleated electret film laminate 5 is formed by adhesion or fusing.

In this example, the pleated electret film 1
．． 1. 1. It is desirable that the distances between the films in the lamination direction be equal, that is, that each film be placed at a position parallel to the lamination direction.

In the second embodiment shown in FIG. 2, an electret film 6 is folded into a continuous pile shape, and pleats 7 are formed on the entire surface of the film to increase its thickness, and a large number of continuous voids 8 of strained cylinders are created. The electret films 6 are stacked in the thickness direction with an ordinary flat film 9 interposed between them, and flat films 9 are attached on the top and bottom, and the tips of the pleats are glued or fused to the flat film to produce a pleated electret film. constitutes a laminate 10.

The third embodiment shown in FIG.
is continuously folded into a vertically elongated trapezoid shape to form pleats 12 on the entire surface of the film to increase its thickness and create a large number of prismatic cylindrical continuous voids 13, and fold this pleated electret film 11 in the thickness direction. The pleat tips 14 of the pleats are adhered or fused to form a laminate 15 of pleated electret films.

The fourth embodiment shown in FIG.
6 is continuously bent into a pulse wave shape, small pleats 17 are formed on the entire surface of the film to increase the thickness, and a continuous gap 18 in the form of a rectangular cylinder is created. The tip 19 of the electret film is adhered or fused to the film surface to form a pleated electret film laminate 20.

In these examples, the films are fixed by adhesion or fusing, but depending on the application, the films may be overlapped and fixed by pressing from both sides to construct a filter.

FIG. 5 shows a specific example of a filter, in which a multilayer product 5 of a pleated electret filter is inserted into a box frame 21 with both front and rear sides cut out, and the air to be purified is passed through the box frame 21.
It flows in the front-back direction of 1 and passes through the continuous gap 3...

As shown in the first to fourth embodiments of the present invention, an electret film is continuously folded or folded to form pleats 2.0 on the entire surface of the film. 7. 12. 17, the pleated electret films 1゜6.11.16 are stacked in the thickness direction, and the tips of the pleats are glued or fused to form a laminate product 5.10゜15.20 as the main part of the filter. The air to be purified flows in the direction of the folds and forms continuous voids.3. 8. 12. Pass 18.

In the present invention, since the contact area between the air and the electret film is expanded, the dust collection efficiency is improved, and since the air can easily circulate, there is less pressure loss. Because it is a filter, it does not lose its shape, and because it does not flap during use, the dust that has adhered to it does not fly away, and these factors combine to provide a filter with excellent dust collection performance and a long service life.

The filter according to the present invention is a conventional nonwoven fabric filter A,
Table 1 shows a comparison with Filters B, C, and Filter D, which is a laminated layer of flat Electre I film.

As is clear from Table 1, the present invention has a pressure loss of 0 and high efficiency.

On the other hand, among the nonwoven fabric filters, A has relatively low pressure loss but poor efficiency, and B and C have good efficiency but high pressure loss.

Furthermore, a flat electret film laminate has zero pressure loss and relatively good initial efficiency, but the efficiency rapidly decreases over time.

According to the present invention, since it does not flap during use, the dust that has adhered once does not scatter again, the pressure loss is extremely small, so energy can be saved, and the contact area is large, so the dust collection efficiency is high, and the initial efficiency and aging efficiency are Both have many advantages such as being excellent.

[Brief explanation of the drawing]

1 to 4 are front views showing the first to fourth embodiments of the present invention, respectively, and FIG. 5 is a perspective view showing a specific example of the filter. In addition, 1, 6, 11, 16 are pleated electret films, 2. 7. 12. 17 is a pleat, 3, 8.
13. 18 is a continuous void, and 14.19 is the tip of the pleat.

Claims (1)

[Claims] 1. The pleated electret film is produced by continuously bending or folding an electret polymer film to form pleats on the entire surface of the film to increase its thickness and create a large number of continuous voids. An electret filter characterized by being composed of layers stacked in the direction of thickness. 2. The electret filter according to claim 1, wherein the pleated electret films stacked in the thickness direction have tips of the pleats bonded or fused to each other.