JP2022095188A - Air filter and method for manufacturing air filter - Google Patents

Abstract

To provide an air filter excellent in charging performance of a filter medium, and a method for manufacturing the same.SOLUTION: An inventive air filter has a thickness of a hot melt resin for bonding a charged filter medium and a frame material included in the air filter of 600 μm or thicker; accordingly the charged filter medium is less likely to be heated when the hot melt resin is heated from the outside of the frame material and is melted; thereby attenuation of charging of the filter medium due to heat is less likely to occur; and charging performance is excellent. A method for manufacturing the air filter heats a hot melt resin from the outside of the frame material at VICAT softening point+50°C or lower, and melts the hot melt resin; accordingly the charged filter medium is less likely to be heated when the hot melt resin is heated and melted; thereby attenuation of charging of the filter medium due to the heat is less likely to occur; and charging performance is excellent.SELECTED DRAWING: None

Description

The present invention relates to an air filter and a method for manufacturing an air filter.

Conventionally, as disclosed in Patent Document 1, an air that includes a charged filter medium and a frame material that surrounds the outer peripheral side surface of the filter medium, and the filter medium and the frame material are bonded with an adhesive such as a hot melt resin. The filter is used by being incorporated in an air purifier or the like. When the filter medium and the frame material are bonded with a hot melt resin, a hot melt resin is interposed between the filter medium and the frame material surrounding the outer peripheral side surface of the filter material, and the hot melt resin is used from the outside of the frame material with a hot plate or the like. Is generally heated and melted, and then the hot melt resin is cooled and solidified.

Japanese Unexamined Patent Publication No. 5-103936

However, the air filter disclosed in Patent Document 1 is used when the hot melt resin is heated to melt the hot melt resin for the purpose of bonding the filter medium and the frame material with the hot melt resin at the time of manufacturing the air filter. , The filter medium is heated, and the charge of the filter medium is attenuated by the heat, which may reduce the collection efficiency of the air filter.

The present invention has been made under such circumstances, and provides an air filter having excellent charging performance of the filter medium, and an air filter having excellent charging performance of the filter medium because the charge of the filter medium is not easily attenuated by heat. The purpose is.

The invention according to claim 1 of the present invention includes "a filter medium composed of a charged porous body, a frame material surrounding the outer peripheral side surface of the filter material, and a hot melt resin for adhering the filter material and the frame material, as described above. An air filter having a thickness of 600 μm or more of a hot melt resin that adheres a filter medium and a frame material. ”

The invention according to claim 2 of the present invention is "the air filter according to claim 1, wherein the VICAT softening point of the hot melt resin is 44 ° C. or lower."

According to the third aspect of the present invention, "the outer peripheral side surface of the filter medium and the frame material are brought into contact with each other with a hot melt resin interposed therebetween, and the hot melt resin has a VICAT softening point of + 50 ° C. or less from the outside of the frame material. The method for manufacturing an air filter according to claim 1 or 2, further comprising a step of heating to melt the hot melt resin and adhering the filter medium and the frame material with the hot melt resin. "

In the air filter according to claim 1 of the present invention, since the thickness of the hot melt resin that adheres the charged filter medium and the frame material contained in the air filter is as thick as 600 μm or more, the hot melt resin is applied from the outside of the frame material. Since the charged filter medium is not easily heated when the hot melt resin is heated, it is difficult for the charge of the filter medium to be attenuated by heat, and an air filter having excellent charging performance can be realized.

The air filter according to claim 2 of the present invention has a VICAT softening point of 44 ° C. or lower, which is as low as 44 ° C. or lower. Therefore, when the hot melt resin is heated to melt the hot melt resin, the hot melt resin is heated at a low temperature. Since it is possible to melt the charged filter medium and the charged filter medium is not easily heated, it is difficult for the charge of the filter medium to be attenuated by heat, and an air filter having excellent charging performance can be realized.

In the method for manufacturing an air filter according to claim 3 of the present invention, since the hot melt resin is melted by heating from the outside of the frame material at a VICAT softening point + 50 ° C. or lower, the hot melt resin is heated to form the hot melt resin. Since the charged filter medium is not easily heated when it is melted, it is difficult for the charge of the filter medium to be attenuated by heat, and it is a method for manufacturing an air filter having excellent charging performance.

The air filter of the present invention contains a filter medium composed of a charged porous body, a frame material surrounding the outer peripheral side surface of the filter medium, and a hot melt resin for adhering the filter medium and the frame material, and the filter medium and the frame material are combined. The thickness of the hot melt resin to be adhered is 600 μm or more. Due to the thick thickness of the hot melt resin, when the hot melt resin is heated from the outside of the frame material to melt the hot melt resin, the charged filter medium is not easily heated, so that the charge of the filter medium is attenuated by heat. Can be realized with an air filter that is less likely to occur and has excellent charging performance. The thicker the hot melt resin, the less likely it is that the charged filter medium will be heated and the attenuation of the charge of the filter medium due to heat will be less likely to occur. Therefore, the thickness of the hot melt resin is preferably 700 μm or more, preferably 800 μm or more. .. If the thickness of the hot melt resin is too thick, the hot melt resin may flow out of the air filter when the hot melt resin is melted, which may contaminate the machine used for melting the hot melt resin. The upper limit of the thickness of the hot melt resin is practically 1600 μm or less. For the thickness of the hot melt resin, see a cross-sectional photograph of the frame material in the air filter where the filter medium and the frame material are not adhered and the hot melt resin is present, and the cross section of the frame material is enlarged with a microscope. Take a picture, measure the thickness of the hot melt resin at 5 points per one cross-sectional photograph, and refer to the average value.

As the constituent resin of the hot melt resin, for example, ethylene vinyl acetate resin, polyolefin resin (polypropylene, polyethylene, etc.), polyester resin, or the like can be used. Among these, ethylene vinyl acetate resin, which has a low VICAT softening point and can melt the hot melt resin at a low temperature, is preferable. The VICAT softening point of the present invention is a value measured in accordance with the A50 method of JIS K 7206 (2016) "Plastic-thermoplastic plastic-how to obtain Vicat softening temperature (VST)". Further, the hot melt resin contained in the air filter of the present invention may be one kind or two or more kinds.

When the VICAT softening point of the hot melt resin is 44 ° C. or lower, the hot melt resin can be melted at a low temperature, and when the hot melt resin is heated to melt the hot melt resin, the filter medium is not easily heated and is caused by heat. It is preferable because the charge of the filter medium is less likely to be attenuated.

The hot melt resin may be present on the entire surface of the main surface of the frame material on the side where the frame material and the filter medium are in contact, or may be partially present on the side where the frame material and the filter medium are in contact with each other. The hot so that the frame material and the filter medium can be firmly adhered to each other, and the particles permeate through the gap generated between the frame material and the filter medium to suppress the increase in the permeability of the air filter. It is preferable that the melt resin is present on the entire surface of the frame material on the side where the frame material and the filter material come into contact with each other. The main surface is the widest surface.

As the porous body which is the filter medium constituting the air filter of the present invention, for example, a non-woven fabric, a woven fabric, a knitted fabric, a microporous membrane or the like can be used, but the coarse and dense structure in the thickness direction in the porous body can be easily adjusted. A non-woven fabric is preferable because it can be formed and the efficiency of collecting dust is excellent.

The filter medium is preferably pleated with a pleating device or the like so that the dust collection efficiency is excellent.

The filter medium is charged. As the charging method of the filter medium, various methods such as charging by corona discharge and charging using a polar solvent such as water (for example, the charging method disclosed in Japanese Patent Application Laid-Open No. 2003-205210) can be adopted, and are particularly limited. It's not something to do.

The constituent resin of the filter medium is not particularly limited, but may be, for example, a polyolefin-based resin, a polyester-based resin, a polyamide-based resin, or the like.

The basis weight of the filter medium is not particularly limited, but is preferably 45 to 250 g / m ² so that the dust collection efficiency is excellent and the processability (pleating, etc.) is excellent. It is more preferably 55 to 200 g / m ² , and even more preferably 65 to 160 g / m ² . Similarly, the thickness of the filter medium is not particularly limited, but is 0.1 to 3.5 mm so that the dust collection efficiency is excellent and the workability (pleating, etc.) is excellent. It is preferably present, more preferably 0.2 to 2.5 mm, and even more preferably 0.3 to 1.5 mm. The basis weight is the area per 1 m ² of the main surface, and the thickness of the filter medium / frame material is the thickness under a load of 2 kPa.

As the frame material constituting the air filter of the present invention, for example, a breathable member such as a non-woven fabric, a woven fabric, a knitted fabric, or a microporous film, or a non-breathable member such as a resin sheet can be used, but the workability is high. A non-woven fabric is preferable because it is excellent and the pressure loss of the air filter does not easily increase.

The constituent resin of the frame material is not particularly limited, but for example, a resin similar to the constituent resin of the filter medium, such as a polyolefin-based resin and a polyester-based resin, can be used.

The basis weight of the frame material is not particularly limited, and can be 50 to 500 g / m ² , 100 to 450 g / m ² , and 150 to 400 g / m ² . Similarly, the thickness of the frame material is not particularly limited, and can be 0.2 to 1.0 mm, 0.3 to 0.9 mm, and 0.4 to 0. It can be 8 mm.

The transmittance of the air filter of the present invention can be an air filter having a low-performance filter medium having a transmittance of 40% or more, and an air filter having a medium-performance filter medium having a transmittance of 1% or more and 40% or less. It can be an air filter having a high performance filter medium with a collection efficiency of 1% or less. Among these, the air filter of the present invention has a thick hot melt resin, which makes it difficult for the charged filter medium to be heated when the hot melt resin is heated from the outside of the frame material to melt the hot melt resin. Since it is difficult to receive the attenuation of the charge due to heat, it is preferable to use an air filter having a high-performance filter medium having a transmittance of 1% or less, in which the attenuation of the charge due to heat greatly affects the permeability. The term "permeability" as used herein means that after setting the air filter in the holder of the test duct, atmospheric dust having a particle diameter of 0.3-0.5 μm (atmospheric dust number: U) is placed on the upstream side of the air filter. Particle counter (manufactured by RION: model KC-22B) measures the number of atmospheric dust (D) with a particle diameter of 0.3-0.5 μm on the downstream side when supplied and passed through air with a test air volume of 50 m ³ / h. The value measured by and calculated from the following formula.
Transmittance (%) = (D / U) x 100

Next, a method for manufacturing the air filter of the present invention will be described.

First, the outer peripheral side surface of the filter medium and the frame material are brought into contact with each other with a hot melt resin interposed therebetween. As the hot melt resin used at this time, the above-mentioned hot melt resin can be used. As a method of contacting the outer peripheral side surface of the filter medium and the frame material with a hot melt resin interposed therebetween, for example, the hot melt resin is applied to the frame material, and the outer peripheral side surface of the filter medium and the hot melt resin of the frame material are provided. The method of contacting with the main surface and the method of interposing a sheet made of hot melt resin between the outer peripheral side surface of the filter medium and the frame material are not particularly limited. Further, when the outer peripheral side surface of the filter medium and the frame material are brought into contact with each other with a hot melt resin interposed therebetween, even if the hot melt resin is provided on the entire surface of one of the main surfaces of the frame material, one of the frame materials is provided. It is possible to have the hot melt resin only on a part of the main surface of the filter material, but the particles may be formed from the gap generated between the frame material and the filter material so that the filter material and the frame material can be firmly adhered to each other. It is preferable to have the hot melt resin on the entire surface of one of the main surfaces of the frame material so that the permeation can be suppressed from increasing the permeation rate of the air filter.

Next, the hot melt resin is melted by heating from the outside of the frame material at the VICAT softening point + 50 ° C. or lower of the hot melt resin, and the filter medium and the frame material are bonded with the hot melt resin. Since the heating temperature when melting the hot melt resin is as low as the VICAT softening point + 50 ° C or less of the hot melt resin, it is difficult for the charged filter medium to be heated. Excellent charging performance. As a method of heating the hot melt resin from the outside of the frame material, for example, heating with a hot plate can be mentioned.

Examples of the present invention will be described below, but the present invention is not limited to the following examples.

(Example 1)
(Manufacturing of filter media)
4 parts by mass of a hindered amine-based light stabilizer was mixed as a charging aid with 100 parts by mass of a commercially available polypropylene resin having a volume specific resistance value of 10 ¹⁶ (Ω · cm), and this mixture was spun by a melt blow method. A melt-blown nonwoven fabric made of polypropylene resin (fiber cross-sectional shape: circular, average fiber diameter: 1.7 μm, grain: 45 g / m ² , thickness: 0.33 mm) was produced.
Next, a spunbonded non-woven fabric composed of polyethylene terephthalate resin (fiber cross-sectional shape: irregular shape in which four Y-shaped protrusions protrude from the center, fineness: 16dtex, basis weight: 60 g / m ² , thickness: 0. .42 mm) was prepared.
Next, the main surface of the melt-blow non-woven fabric and the main surface of the spun-bonded non-woven fabric are brought into contact with each other and subjected to an ultrasonic fusion device in a state of being merely overlapped, and one of the main surfaces of the melt-blow non-woven fabric and the spun-bonded non-woven fabric. A laminated nonwoven fabric was manufactured by laminating and integrating the melt-blown nonwoven fabric and the spunbonded nonwoven fabric by applying ultrasonic waves to the portions.
Next, a charged laminated nonwoven fabric was produced by a charging method using water as a polar solvent disclosed in Japanese Patent Application Laid-Open No. 2003-205210.
Finally, the charged laminated nonwoven fabric was pleated to produce a filter medium (weight: 105 g / m ² , thickness: 0.75 mm, pitch: 4.4 mm, mountain height: 27 mm).
(Preparation of frame material A having hot melt resin A)
It has a hot melt resin A coated with ethylene / vinyl acetate hot melt resin A (VICAT softening point: 41 ° C.) on the entire surface of one main surface of a polyethylene terephthalate spunbonded non-woven fabric (grain: 225 g / m ² ). Frame material A (grain: 795 g / m ² ) was prepared.
(Manufacturing of air filter)
The filter medium and the frame material A having the hot melt resin A are brought into contact with each other so as to surround the outer peripheral side surface of the filter medium and so that the hot melt resin A contained in the frame material A and the filter medium are in contact with each other, and hot from the outside of the frame material A. An air filter (width: 180 mm, depth: 90 mm) in which the filter medium and the frame material A are bonded with the hot melt resin A by heating the hot melt resin A at 90 ° C. so that the plate and the frame material A are in contact with each other and cooling the hot melt resin A. , Height: 29 mm, total thickness of spunbonded non-woven fabric and hot melt resin A, which is a frame material constituting the air filter: 1.2 mm, thickness of the hot melt resin A: 600 μm) was manufactured.

(Example 2)
(Manufacturing of filter media)
The same pleated filter media as in Example 1 was produced.
(Preparation of frame material B having hot melt resin B)
It has a hot melt resin B coated with ethylene / vinyl acetate hot melt resin B (VICAT softening point: 45 ° C.) on the entire surface of one main surface of a polyethylene terephthalate spunbonded non-woven fabric (grain: 225 g / m ² ). Frame material B (grain: 783 g / m ² ) was prepared.
(Manufacturing of air filter)
The filter medium and the frame material B having the hot melt resin B are brought into contact with each other so as to surround the outer peripheral side surface of the filter medium and so that the hot melt resin B possessed by the frame material B is in contact with the filter medium, and hot from the outside of the frame material B. An air filter (width: 180 mm, depth: 90 mm) in which the filter medium and the frame material B are bonded with the hot melt resin B by heating the hot melt resin B at 120 ° C. so that the plate and the frame material B are in contact with each other and cooling the hot melt resin B. , Height: 29 mm, total thickness of spunbonded non-woven fabric and hot melt resin B as a frame material constituting the air filter: 1.2 mm, thickness of the hot melt resin B: 600 μm) was manufactured.

(Comparative Example 1)
(Manufacturing of filter media)
The same pleated filter media as in Example 1 was produced.
(Preparation of frame material C having hot melt resin A)
It has a hot melt resin A coated with ethylene / vinyl acetate hot melt resin A (VICAT softening point: 41 ° C.) on the entire surface of one main surface of a polyethylene terephthalate spunbonded non-woven fabric (grain: 225 g / m ² ). Frame material C (grain: 605 g / m ² ) was prepared.
(Manufacturing of air filter)
The filter medium and the frame material C having the hot melt resin A are brought into contact with each other so as to surround the outer peripheral side surface of the filter medium and so that the hot melt resin A contained in the frame material C is in contact with the filter medium, and hot from the outside of the frame material C. An air filter (width: 180 mm, depth: 90 mm) in which the filter medium and the frame material C are bonded with the hot melt resin A by heating the hot melt resin A at 90 ° C. so that the plate and the frame material C are in contact with each other and cooling the hot melt resin A. , Height: 29 mm, total thickness of spunbonded non-woven fabric and hot melt resin A, which is a frame material constituting the air filter: 1.0 mm, thickness of the hot melt resin A: 400 μm) was manufactured.

(Comparative Example 2)
(Manufacturing of filter media)
The same pleated filter media as in Example 1 was produced.
(Preparation of frame material D having hot melt resin B)
It has a hot melt resin B coated with ethylene / vinyl acetate hot melt resin B (VICAT softening point: 45 ° C.) on the entire surface of one main surface of a polyethylene terephthalate spunbonded non-woven fabric (grain: 225 g / m ² ). A frame material D (grain: 597 g / m ² ) was prepared.
(Manufacturing of air filter)
The filter medium and the frame material D having the hot melt resin B are brought into contact with each other so as to surround the outer peripheral side surface of the filter medium and so that the hot melt resin B of the frame material D is in contact with the filter material, and hot from the outside of the frame material D. An air filter (width: 180 mm, depth: 90 mm) in which the filter medium and the frame material C are bonded with the hot melt resin B by heating at 120 ° C. so that the plate and the frame material C are in contact with each other to melt the hot melt resin B and cooling the hot melt resin B. , Height: 29 mm, total thickness of spunbonded non-woven fabric and hot melt resin B as a frame material constituting the air filter: 1.0 mm, thickness of the hot melt resin B: 400 μm) was manufactured.

The air filters of Examples and Comparative Examples were evaluated by the following methods.

(Measurement of transmittance)
The air filter is attached to the measuring tool with the fiber layer derived from the spunbonded nonwoven fabric of the filter medium on the upstream side and the fiber layer derived from the melt blow nonwoven fabric of the filter medium on the downstream side, installed in the test duct, and measured by the above-mentioned method for measuring the permeability. did. The number of atmospheric dust (U) supplied to the upstream side of the air filter in this measurement was 60,000.

The thickness and VICAT softening point of the hot melt resin used in the air filters of Examples and Comparative Examples, and the results of the transmittance of Examples and Comparative Examples are shown in Table 1 below.

As a result of comparing Example 1 and Comparative Example 1 and Example 2 and Comparative Example 2, the thickness of the hot melt resin in the air filter of the present invention is large, so that the charge is attenuated by the heat of the filter medium constituting the air filter. It was found that the air filter of the present invention is an air filter having excellent charging performance of the filter medium and excellent collection efficiency, because the air filter is less likely to occur and the transmittance of dust is lowered.

Further, as a result of comparing Example 1 and Example 2, the air filter of Example 1 has a lower VICAT softening point of the hot melt resin constituting the air filter as compared with the air filter of Example 2, and at a lower temperature. Since the hot melt resin can be melted, the charge is less likely to be attenuated by the heat of the filter medium constituting the air filter, and the dust permeability is low. Therefore, the air filter of Example 1 has excellent charge performance of the filter medium. It was found that the air filter has excellent collection efficiency.

The air filter of the present invention can be used by incorporating it into an air conditioner installed in, for example, a building, a factory, a general household, or the like.

Claims (3)

A filter medium composed of a charged porous body, a frame material surrounding the outer peripheral side surface of the filter medium, and a hot melt resin for adhering the filter medium and the frame material, and a thickness of the hot melt resin for adhering the filter medium and the frame material. An air filter with a diameter of 600 μm or more. The air filter according to claim 1, wherein the VICAT softening point of the hot melt resin is 44 ° C. or lower. The outer peripheral side surface of the filter medium and the frame material are brought into contact with each other with a hot melt resin interposed therebetween, and the hot melt resin is melted by heating from the outside of the frame material at the VICAT softening point + 50 ° C. or lower of the hot melt resin to melt the filter medium. And the process of adhering the frame material with hot melt resin,
The method for manufacturing an air filter according to claim 1 or 2, wherein the air filter has.