JPH0445813A - Filter unit - Google Patents

Abstract

PURPOSE:To produce the unit which is low in pressure drop and has high capturing efficiency and to enhance productivity by inserting a prescribed filter medium having <0.15 denier average fineness between prescribed nonwoven fabric separators having >=7 denier average fineness and folding the layers zigzag. CONSTITUTION:The filter medium 3 which is constituted of the fibers having <0.15 denier average fineness and has <100mm bending resistance is inserted between the nonwoven fabric separators 2 which are constituted of the fibers having >=7 denier average fineness and have >=100mm bending resistance, >=1.0mm thickness, and >=1,000cc/cm<2>.sec air permeation rate. The separator layers are folded zigzag in this state to constitute the filter unit 1. The filter medium 3 is securely fixed by folding the layers zigzag in such a manner and, therefore, the air flow passing the filter medium 3 is uniformized and the filter medium characteristics are stabilized. The folding zigzag of the nonwoven fabric separators and the filter medium in the laminate state is equally well and the folding zigzag after these layer and medium are previously bonded over the entire part or partially in also well.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a filter unit excellent in low pressure loss properties, which is made by folding a non-woven fabric made of a particularly soft organic polymer with an average fineness of less than 0.15 denier. .

[Prior art] Sturdy and hard pine I made mainly of glass fiber
The conventional method for manufacturing a filter unit from a filter medium is to fold the filter medium through a separator called a separator made of non-porous aluminum, paper, or plastic. ,
Filter units are being manufactured that can accommodate a large amount of filter media in a limited unit volume and handle a large amount of air with low pressure loss.

However, like melt-blown nonwoven fabrics made of organic polymer fibers with an average fineness of less than 0.15 denier,
In particular, when a filter unit is made using a conventional method using a soft nonwoven fabric sheet with no stiffness, the filter medium deforms and comes into close contact with the separator, resulting in many areas where air cannot pass through.

Therefore, the effective area of the filter medium is substantially reduced, resulting in an increase in pressure loss and a decrease in collection efficiency.

Further, Japanese Patent Application Laid-Open No. 62-213818 discloses a filter medium for an air filter in which a cotton-like filter body is disposed on the upstream side of the air flow and a charged filter body is disposed on the downstream side thereof. In this known example, the cotton-like filter has the function of a filter and has the effect of a pre-filter. Therefore, those with high ventilation resistance and pressure loss of 10 mmAq, and high collection efficiency of 70%, are used. Furthermore, the concept of sandwiching the charged filter body between cotton-like filter bodies was also not presented. Collection efficiency (0.1 μm particles) where no pre-filter effect is expected as in the present invention
In this case, there was no concept of sandwiching the main filter medium between filter media with a content of less than 5%.

[Problems to be Solved by the Invention] The present invention is particularly applicable to the case where a nonwoven fabric sheet made of a soft organic polymer is used as a filter medium, and the conventional method using a non-breathable separator folded at peaks and valleys,
This solves the problems of increased pressure loss and decreased collection efficiency, which occur as a result of the separator and filter media coming into close contact and reducing the effective area of the filter media.

[Means to solve the problem] The present invention has the following configuration.

That is, between the nonwoven fabric separator layers, which are composed of fibers with an average fineness of 7 deniers or more, have a bending resistance of 100 mm or more, a thickness of −,0 mm or more, and an air permeability of 1000 cc/cm 2 ・800 or more, ．． This is a filter unit that is folded in a mountain-valley manner with a filter medium made of fibers of less than 15 deniers and having a bending resistance of less than 100 mm sandwiched therein.

[Function] The structure of the filter unit of the present invention will be explained in detail with reference to the drawings. Figs. 1 and 2 show the cross-sectional structure of the filter unit 1 of the present invention folded in a peak-valley manner.

To explain in more detail, the average fineness is 7 denier or more, the bending resistance is 100 mm or more (evaluation method using a 45° cantilever), the thickness is 1.0 mm or more, and the airflow rate is 1000 CC/Cm.
A nonwoven fabric separator 2 with a bending strength of 10 and made of fibers with an average fineness of less than 0.15 denier is placed between the nonwoven fabric separators 2 and 2.
It shows how the filter medium of less than 0 mm is sandwiched and folded into peaks and valleys.

The nonwoven fabric separator has an average fineness of 7 denier or more, a bending resistance of 1.00 mm or more, a thickness of 1.0 mm or more, and an air permeability of 1000 cc/cm2.800 or more (evaluation method J I
5-L1096) is a relatively hard nonwoven fabric with excellent breathability, and its airflow rate is 1000cc/cm'.
880 or more, bending resistance of nonwoven fabric separator] -00m
It is preferable to have as many as possible while maintaining m or more. This is because the purpose of using the nonwoven fabric separator is to separate the filter medium 3 and maintain the shape of the filter unit structure, and it is desirable that the ventilation resistance be as low as possible.

If the bending resistance is less than 100 mm, it is not preferable because the mountain-valley folded form cannot withstand compression and deformation due to wind pressure.

For this reason, it is preferable to use a thick and hard fiber as a constituent material. For this reason, hard and rigid fibers with an average fineness of 7 deniers or more are suitable. Among these, polyester short fibers and composite short fibers (for example, the core is made of polypropylene and the sheath is made of polyethylene) are suitable.

If the constituent fibers are thick fibers with a fineness exceeding 100 deniers, the fibers may close the gaps between the peaks and valleys of the folded ridges, which is not preferable.

As for the fiber material, fibers such as polyamide, polyester, and polyolefin can be widely used and are preferred. Moreover, a material having a hardness exceeding 1.000 mm is not preferable because it is too hard and the height of the pleats becomes uneven during pleating.

In particular, nonwoven fabric separators containing heat-adhesive fibers have a large amount of airflow, and after being folded into peaks and valleys, heat treatment can bond the fibers that touch the slopes of the peaks, making the folded form even more stable. It is preferable because it can be strengthened.

Further, when using a nonwoven fabric Sepa I knotter that has been bonded with resin in advance, it is advantageous in terms of shape retention because it can be made relatively hard. Furthermore, when a nonwoven fabric containing heat-adhesive fibers is bonded with resin, it is hard and has excellent shape retention, and by heat treatment, it is also possible to bond the fibers that are on the slopes of the mountain, making the shape of the mountain-valley fold even more appealing. It is more preferable because it can be stably reinforced.

Moreover, the thickness is 1 mm or more. 1. At the end of mm, it is necessary for air to flow smoothly and without resistance between the fibers that make up the nonwoven fabric separator, so if it is too narrow, the fibers will block the flow, resulting in loss of air permeability and high pressure loss, so it is not suitable. do not have.

As for the basis weight, it is necessary to reduce the ventilation resistance, so it is preferable to reduce it as much as possible while maintaining a bending resistance of 100 mm or more (7.5 mm. Generally 1-0
A range of ~300 g/m2 is preferred.

The filter medium layer 3 has a bending resistance of less than 100 mm and an average fineness of 0.1.
It is a flexible non-woven layer composed of fibers of less than 5 denier. When used for building air conditioning or as a filter for clean rooms, in order to reduce the amount of dust after filtration to less than 0.1-5 mg/m', non-woven fabrics containing fibers with a fineness of less than 0.15 denier can efficiently remove dust. It is suitable because it collects For example, short fiber nonwoven fabrics, spunbond nonwoven fabrics, melt blown nonwoven fabrics, nonwoven fabrics produced by flash spinning, nonwoven fabrics produced by collecting solution polymers in an electrostatic field, etc. can be suitably used. Among them, melt-blown nonwoven fabrics are suitable because they can easily be made fine in fineness and have high collection efficiency. In particular, a treaded melt-blown nonwoven fabric is most suitable because it has low pressure loss and extremely high collection efficiency.

Generally, the preferable range is a fineness of 0.003 denier or more and 0.1 denier. These nonwoven fabrics alone,
Lamination or composite/adhesion1. It is used for Also,
It is used by laminating, combining, or adhering other materials that do not meet the requirements of the filter medium layer 3.

Regarding the bending resistance of the filter layer, softer nonwoven fabrics,
When unitized using the method of the present invention, it is advantageous in terms of the effects obtained, namely low pressure loss, morphological stability, and low cost, but the unit size is in the range of 20 mm to 100 mm with a basis weight of 20 g/m'. It is preferable because it has process passability (strength) when forming.

The components of fiber materials include fibers made of inorganic fibers such as glass and asbestos, and organic polymers such as polyamide, polyester, polyolefin, and polycarbonate, and especially for elect-knot products, organic polymers such as polypropylene, polycarbonate, polyester, and polyurethane fibers. Fibers made of coalesced fibers are inexpensive and suitable materials.

The basis weight is determined by the required filtration characteristics.
There are no particular limitations on the use of the method of the present invention. Generally, it is preferable that the amount is within the range of 5 to 300 g/m2.

A characteristic method of the present invention is to sandwich the filter moon 3 between nonwoven fabric separators and fold them together in peaks and valleys. In the conventional filter unit, a separator folded in peaks and valleys functions to separate the filter medium 3, but in the method of the present invention, a nonwoven fabric separator I noter fulfills this function.

In addition, as shown in Figure 1, the nonwoven fabric separator is
May be folded in peaks and valleys so that the surfaces touch each other1
-1 Of course, you can also fold the peaks and valleys with a gap of several millimeters as shown in Figure 2. Furthermore, it is more preferable to bond the peaks of the nonwoven fabric separator in stripes at appropriate intervals with an adhesive component (4 in FIG. 2), since this will provide reinforcement. When this reinforcement is to be performed, reinforcement may be performed by bonding with an adhesive component in the form of a lattice, diagonal stripes, etc., instead of such a line.

Since the filter medium 3 can be firmly fixed by folding the filter medium 3 in this manner, the amount of air passing through the filter medium 3 is made uniform, and the characteristics of the filter medium are stabilized.

Furthermore, the nonwoven fabric separator and the filter medium may be folded in a laminated state, or may be folded in peaks and valleys after being adhered in whole or in part in advance. Furthermore, a nonwoven fabric having other functions other than the filtering medium, such as a bulky nonwoven fabric that increases deodorizing properties, aromatic properties, antibacterial and antifungal properties, and dust retention, may be used in combination with the filtering medium between the nonwoven fabric separator layers.

[Example] Example 1 - As a nonwoven fabric separator, a 15 denier polyester short fiber nonwoven fabric (mixing ratio of both fibers 2:8), whose core was polypropylene and sheath was bonded with a polyethylene composite fiber with a fineness of 10 denier, was used. Length 75mm, basis weight 50g/m
2. Thickness 2.5mm.

Bending resistance 150mm, airflow rate 1030cc/cm'・s
During e c), a polypropylene electret melt-blown nonwoven fabric (average fineness 0.04 denier, mesh size 1'20 g/m2, thickness 0° 1.4 mm, bending resistance 30 mm, collection efficiency 85%, A filter unit in which the polyethylene composite fibers were melted and the fibers were fused together was manufactured by folding the fibers (surface potential 150 V) into peak-valley folds with a folding pitch of 5.2 mm and a peak height of 30 mm.

The characteristics of this filter unit are that the passing wind speed is 6m/min.
As a result of evaluating the pressure loss and collection efficiency (0.3 μm particles), the pressure loss was 3 mmAq and the collection efficiency was 80%.

Comparative Example 1 A conventional filter that was folded using only the filter medium 3 used in the example with a folding pitch of 5.2 mm and a peak height of 30 mm through an aluminum separator (thickness 0.15 mm, peak height 5 mm). produced the unit.

The characteristics of this filter unit are that the passing wind speed is 6m/min.
As a result of evaluating the pressure loss and collection efficiency (0.3 μm particles), the pressure loss was 1.0 mmAq and the collection efficiency was 60%.

It is clearly seen that the filter unit manufactured by the method shown in the examples of the present invention has superior characteristics.

Comparative Example 2 Non-woven fabric separator with fineness of 5.5 denier,
J'200 g 7m2, thickness 2. Omm, bending resistance 8Q
As the filter medium 3, a polypropylene electret melt-blown nonwoven fabric (
Average fineness 0.04 denier, basis weight 20g/m2, thickness 0
．． A filter unit was fabricated by folding a sheet (1° 4 mm, collection efficiency 85%, surface potential 150 V) at a fold pitch of 5.2 mm and a peak height of 30 mm.

The characteristics of this filter unit are that the passing wind speed is 6m/min.
As a result of evaluating the pressure loss and collection efficiency (0.3 μm particles), the pressure loss was 15 mmAq and the collection efficiency was 62%.

It is clear that the pressure loss is higher than that of the examples, and it can be seen that the filter unit manufactured using the filter medium of the present invention has superior characteristics.

[Effects of the Invention] The effects of the present invention are that since a nonwoven fabric with excellent air permeability is used as a separator to form a unit, it is possible to manufacture a unit with low pressure loss and high collection efficiency. In addition, productivity is high because the machine can perform mountain-valley folding (pleating).

Since a soft filter medium is sandwiched between firm and hard non-woven separators, there is no need to combine it with a material that provides special formability. Furthermore, since mechanical folding is possible, it is effective in reducing costs.

Since the shape can be stabilized in the peak-valley folded state, it is possible to use multiple layers of the same nonwoven fabric or nonwoven fabrics with different performance and configuration conditions in the filter 3 by adhering or laminating them.

Since the nonwoven fabric separator has the function of a coarse dust filter, it is possible to manufacture a filter unit with a relatively long life.

[Brief explanation of the drawing]

FIG. 4 and FIG. 2 are schematic model diagrams showing the cross-sectional structure of the filter medium of the present invention folded at peaks and valleys. . 1: Filter unit of the present invention 2: Non-woven fabric separator 3: Filtration 4: Streak adhesive component Patent application filed by Daito Shi Co., Ltd.

Claims (5)

[Claims] (1) Made of fibers with an average fineness of 7 denier or more, bending resistance of 100 mm or more, thickness of 1.0 mm or more, and air permeability of 100 mm.
A filter unit that is folded in peaks and valleys with a filter medium having a bending resistance of less than 100 mm and made of fibers having an average fineness of less than 0.15 denier sandwiched between a nonwoven fabric separator layer of 0 cc/cm^2·sec or more. (2) The filter unit according to claim (1), wherein the nonwoven fabric separator layer is formed by bonding fibers together using low melting point fibers. (3) The filter unit according to claim (1), characterized in that the peaks of the ridges of the nonwoven fabric separator layer are bonded to each other with a resin in a striped manner. (4) Claims (1), (2), or (2) characterized in that the filter medium contains electret fibers.
3) The filter unit described. (5) The filter unit according to claim (4), wherein the electret fiber is a melt-blown nonwoven fabric.