JPH0747211A - Filter and its preparation - Google Patents

Abstract

PURPOSE:To obtain a filter wherein arrangement or pleats is in good order and which hardly gets out of shape. CONSTITUTION:A foamed resin 2 or 3 applied linearly on both faces or one face of a pleated filter medium 1 is placed in a filter A. The foamed resin 2 or 3 is formed by a method wherein a mixture prepd. by mixing a gas for foaming in a molten resin is applied linearly on the surface of the filter medium 1 in the direction crossing the pleat lines of the filter medium and the resin is foamed and, after the resin is solidified the filter medium 1 is pleated. Therefore, the foamed resin is flexible, lightweight and elastic and even after it is solidified, pleating of the filter medium is easy to be performed and there exists no possibility of breaking and peeling of the linear applied resin after solidification.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a filter comprising a pleated filter medium and a method for producing the same.

[0002]

2. Description of the Related Art It is widely practiced to remove dust by passing air or other fluid through a filter material obtained by pleating a filter material such as nonwoven fabric. Since the filter material is pleated in order to maximize the filtration area corresponding to the passing fluid, it is desirable that the density and height of the pleats are as large as possible for this purpose.

However, if the density and height of the pleats are increased, the folds are bent by the pressure of the passing fluid and the pleats are likely to come into contact with each other. When the pleats are in contact with each other, the filtration area of the filter medium is reduced, the air permeability is reduced, and the pressure loss is increased. Therefore, various measures are used to prevent the pleats from contacting each other. . For example, a filter material before fold-folding is continuously coated with a hot-melt resin linearly in the direction crossing the fold line and then fold-folded, and the hot-solidified crease between the folds of the filter medium after fold-folding is applied. It has been practiced to interpose a melt resin and thereby prevent the folds from bending.

However, since the hot-melt resin must be solidified to some extent before the pleating process, the resin is broken or peeled off at the fold points, and the ridges and valleys of the folds are formed to a predetermined extent. It may not be bent as shown in, but may become rounded. For this reason, it is troublesome to precisely adjust the bending timing or to perform the bending while blowing hot air, and it is difficult to perform the orderly bending. Therefore, it has been attempted to apply the hot-melt resin intermittently in a linear shape so that the resin does not intervene inside the bent portion (the inside of the crests of the peaks or the valleys). This method can improve the easiness of bending to some extent, but it is difficult to accurately perform intermittent coating because the hot melt resin has a high viscosity, and it can be performed when the height of the folds is low (for example, 15 mm or less). Have difficulty.

[0005]

In order to solve the above problems, in the present invention, a foaming resin is used as the hot melt resin applied linearly to the filter medium, and the space between the pleats of the filter medium is used. A flexible and elastic foam resin is interposed between the two.

For example, a foaming gas (for example, nitrogen gas) is mixed with a hot-melt resin in a contact state to form a foaming resin, which is continuously or intermittently applied linearly on a filter material. When the filter material is formed by fold-folding,
A filter medium in which a foamed resin is interposed between the pleats of the filter medium is obtained.

The resin material may be any one used as a hot melt resin and capable of imparting foamability, but from the viewpoint of fineness of texture after foaming, adhesive strength, durability and the like, polyolefin is used. It is preferable to use a system resin. The expansion ratio of the resin is preferably about 2 to 4 times. If the expansion ratio is too small, it tends to show the same defects as in the prior art using a resin that does not expand.If the expansion ratio is too large, the lines become uneven and the compression resistance of the resin after fold folding becomes too small. , There is a possibility that the function as the separator between the folds may not be achieved.

The resin may be applied to the filter medium either continuously (see FIGS. 1 and 2) or intermittently at predetermined intervals (see FIG. 3). From the viewpoint of efficiency, the continuous linear shape is preferable. When it is applied in a continuous linear manner, the coating speed becomes remarkably high, and even when the height of the pleats of the filter medium is very low (for example, 10 mm or less), it can be easily applied. The linear adhesion may be linear or wavy, and in the case of adhering to both the front and back surfaces of the filter medium, it is desirable that the coating lines on the front and back surfaces face each other. This is because if the lines on both the front and back surfaces are significantly misaligned, there is a risk that unwanted undulations will occur in the pleated filter material after production.

[0009]

[Function] Since the foamable hot-melt resin linearly adhered to the surface of the filter medium has a flexible elasticity even after being solidified, the bending resistance when the filter medium is folded is small, and the bending resistance is small. The linear resin located on the outside of the portion greatly extends along the ridge of the fold, and the linear resin located on the inside of the fold is compressed and reduced. Therefore, the filter medium can be bent sharply, and since the adhered resin firmly and elastically adheres to the filter medium, it is not broken or peeled off. Further, since the folding is facilitated and the resin is well adhered, the pleats can be arranged in an extremely orderly manner while facilitating the work during the production, especially during the folding.

[0010]

[Example] A polypropylene nonwoven fabric having a fiber diameter of 10 μm or less produced by laminating a web made of acrylic fiber having a fineness of 2 denier and polyclar fiber with a polyvinylidene chloride adhesive and further laminating it by a melt blow method. 1 and a pleating line for pleats having a width of about 20 mm was added to this filter medium 1, and then both sides thereof were melted at 180 ° C to obtain a polyolefin resin (having a melting point of 180 ° C).
The width of foamable resins 2 and 3 (having a foaming ratio of about 2.5 times) mixed with nitrogen gas to give foamability is about 1.
A 5 mm linear coating was applied continuously.

The melting of the resin, the mixing of nitrogen gas, and the coating on the filter medium were carried out by using a Nordson foam melt adapter modified so as to conform to the practice of the present invention. The resin coating line on both sides of the filter medium was the filter medium. It applied so that it might be in the position which opposes. After the resin has foamed and solidified to the extent that it loses fluidity, the filter material 1 having foamed resins 2 and 3 linearly attached to both sides has a pleat height of about 20 mm and a pleat crest 4 spacing of about 4 mm. Pleated in this manner to obtain Filter A.

After pleating, the filter A is a filter A as shown in the partial perspective view of FIG. 1 and the sectional view of FIG.
The pleats 4 and the troughs 5 are formed in a very orderly manner, and the creases do not become round in the resin-coated portion, and at the time of pleating, the soft resin after foaming is still , Since some viscosity remains, the resin on both sides of the valley of the pleats presses in a flexible state and deforms and sticks to each other, which contributes to maintaining the pleats spacing and aligning the pleats. Admitted.

The above filter was adhered and fixed in a filter frame with an urethane adhesive, mounted on an air conditioner, used for 3 months, then taken out, and the state of the pleats was observed. It was confirmed that the ordered pleated state was maintained without mutual contact with each other or peeling of the applied resin.

[0014]

INDUSTRIAL APPLICABILITY In the present invention, a flexible and elastic foaming resin is used as the resin linearly applied to the surface of the filter medium of the pleat filter in order to maintain the distance between the pleats of the filter medium. Therefore, when the filter media is folded, the peaks and valleys of the pleats will not be rounded due to the appearance.
It is possible to obtain an efficient and beautiful pleated filter in which the pleats are arranged in an orderly manner, and the pleated state can be maintained in an orderly manner for a long time without the resin after solidification breaking or peeling off. Further, by using the foamable resin, it is possible to reduce the amount of resin, reduce the weight of the filter, and the like, and improve the productivity by omitting the troublesomeness of manufacturing such as when using a normal resin. be able to.

[Brief description of drawings]

FIG. 1 is a partial perspective view of a filter of the present invention.

FIG. 2 is a cross-sectional view of an example of the filter of the present invention.

FIG. 3 is a cross-sectional view of another example of the filter of the present invention.

FIG. 4 is a conceptual diagram showing a process flow of a filter manufacturing method of the present invention.

[Explanation of symbols]

 A Filter 1 Filter medium 2 Foamed resin on the front side of the filter medium 3 Foamed resin on the back side of the filter medium 4 Pleated ridges 5 Pleated valleys

Claims (4)

[Claims] 1. A filter having a plurality of pleats in which the filter medium is pleated along a fold line, wherein a foamed resin linearly applied between the pleats and in the direction crossing the fold line of the filter medium. Intervening filter. 2. The filter according to claim 1, wherein the foamed resin applied linearly has a foaming ratio of about 2 to 4 times. 3. The foamed resin is applied to both sides of the filter medium at positions substantially opposite to each other with the filter medium interposed therebetween.
Or the filter according to 2. 4. A hot-melt resin in a molten state is mixed with a gas to form a foamable resin, which is linearly applied to at least one surface of a filter medium having crease lines at predetermined intervals in a direction crossing the crease line. After that, the filter medium is bent in a wavy shape along the crease line to perform pleating so that the solidified linear foam resin is interposed between the pleats.
Filter manufacturing method.