JP2021142505A - Air filter medium - Google Patents

Abstract

To provide an air filter medium low in pressure loss, having sufficient adhesive strength of a fusion part, capable of preventing occurrence of floating or curling-up of a laminated nonwoven cloth and excellent in both dust collection and anti-allergenic performances.SOLUTION: An air filter medium comprises a laminated nonwoven cloth in which two or more nonwoven clothes are bonded by fusion. The haft element formed in the shape of a fusion part forms a haft which indicates a repeating pattern by the group comprising plural elements. The area of one haft element is in a range of 1 to 4.2 mm2, and a shortest distance between adjacent haft elements is 10 mm or less, and the value which is obtained by dividing the closing rate (percentage) of the fusion part equivalent to a fraction of total area in the haft element included in the repeating pattern occupied in the area of the repeating pattern formed by the haft element by the average value of one area of the haft element, is in the range of 0.8 to 1.2%/mm2. The laminated nonwoven cloth is a bonded one in which the nonwoven cloth for a support medium and that for electrification are bonded, and the above cloth for the support medium supports tannin.SELECTED DRAWING: None

Description

The present invention relates to a filter medium for an air filter used in an air conditioner or the like. Hereinafter, "filter material for air filter" may be abbreviated as "filter material".

In recent years, air conditioners such as air conditioners, air purifiers, humidifiers, and dehumidifiers have been widely used in all living spaces such as houses, offices, factories, and automobiles due to changes in the living environment and heightened health consciousness. In these air conditioners, various air filters are often used to obtain purified air. These air conditioners and air filters are required to have higher performance and higher performance year by year.

The air filter is required to have dust collecting performance. In addition to these, deodorizing performance, performance of removing specific harmful gases, antibacterial performance, antiviral performance, anti-allergen performance and the like are required. It is also possible to use an air filter that realizes each performance independently, combine multiple types of air filters as needed to increase the performance, and install it in air conditioning equipment. However, since it is often difficult to take a large space for mounting the air filter, there is a demand for an air filter having high performance by combining a plurality of performances into one air filter.

For example, the anti-allergen performance includes the ability to physically collect substances that cause allergic symptoms such as sneezing, runny nose, and cough (asthma) (hereinafter referred to as "allergen substances"), and the physically collected allergen substances. The ability to deactivate can be mentioned (Patent Documents 1 and 2).

There are various types of air filters, but filter media for air filters made of non-woven fabric are widely used, and various non-woven fabrics are selected and used according to the application and performance. In order to improve the performance and performance, various non-woven fabrics are combined and further combined with different materials to form a filter medium. As a method of combination, a method of laminating a plurality of non-woven fabrics and materials and adhering them to each other is often used.

There is a method of using various adhesives as a method of laminating and laminating non-woven fabrics to form a laminated non-woven fabric, but adhesives may be disliked in applications where odor or outgas generated from the adhesive is a problem. As another method, there is a method of bonding by fusion, which is preferable because no odor or outgas is generated because no adhesive is used. Examples of the fusion method include heat fusion and ultrasonic fusion.

In the case of bonding by fusion, the fused portion of the non-woven fabric is blocked and has no air permeability, and the performance as a filter medium is lost. Therefore, the smaller the area of the fused portion is, the smaller the pressure loss is, which is preferable as a filter medium. On the other hand, if the area of the fused portion is small, the adhesive strength of the fused portion is weakened. In addition, if the area of the non-fused portion is large, floating occurs between the layers of the laminated non-woven fabric, and when the filter medium is cut by post-processing, the non-woven fabric is turned over during the non-fused portion, causing a leak. This is a problem because it leads to defective air filters. Therefore, it is an issue to obtain an excellent filter medium which has low pressure loss, sufficient adhesive strength of the fused portion, and can suppress the occurrence of air filter defects due to floating and curling of the laminated non-woven fabric. rice field.

In Patent Document 3, a heat-fused cellulose fiber containing hydroxymethylzantate is produced from viscose, and a web is formed while making the heat-fused cellulose fiber under a wet condition, and the embossing roller is used to form the web. A regenerated cellulose non-woven fabric sheet formed by heat-sealing the webs to each other while pressing the web to form an embossed web, and a pattern transferred to the embossed web when the embossing roller presses the web. It is composed of a combination of a linear first groove portion and a linear second groove portion, and the end portion of the second groove portion is arranged at a perpendicular position near an intermediate position in the length direction of the first groove portion, and further. By arranging the ends of the first groove in a right angle at a position perpendicular to the intermediate position in the length direction of the second groove, the first groove and the second groove are alternately and continuously connected to the embossed web. A recycled cellulose non-woven fabric sheet characterized by being arranged on the entire surface is disclosed. Further, when the non-fused portion is regarded as the background and the embossed portion (fused portion) is regarded as the handle, in Patent Document 3, the fused portion such as a rectangle is adjacent to the fused portion on the grid points of the square lattice. A pattern is presented in which the orientation is changed by 90 °. However, when the pattern of Patent Document 3 is applied to a filter medium in which a non-woven fabric is laminated, if the lattice is small, the blockage rate is high and the pressure loss is high, and conversely, if the lattice is large, the laminated non-woven fabric stops floating. Was likely to occur, and improvement was needed.

Further, Patent Document 4 discloses an exterior nonwoven fabric used for an absorbent article such as a disposable diaper, and the exterior nonwoven fabric has a plurality of fused portions, and the plurality of fused portions are provided. , A pattern that is repeatedly arranged with regularity so as to touch a virtual circle is disclosed. However, a non-fused portion corresponding to the diameter of the virtual circle is generated, and when the handle of the absorbent article is applied to the filter medium on which the non-woven fabric is laminated, the laminated non-woven fabric is liable to float or turn over, and improvement is required.

Japanese Patent No. 4407851 Japanese Unexamined Patent Publication No. 2005-152793 Utility Model Registration No. 3180626 International Publication No. 2018/123638 Pamphlet

An object of the present invention is to provide a filter medium for an air filter which has low pressure loss, sufficient adhesive strength at a fused portion, can suppress the occurrence of floating and curling of a laminated non-woven fabric, and has excellent dust collection performance and anti-allergen performance. That is.

The problem according to the present invention can be solved by the following means.

A filter medium for an air filter made of a laminated non-woven fabric in which two or more layers of non-woven fabric are bonded, and a plurality of pattern elements formed in the shape of the fused portion are formed by fusion. The area of one pattern element is 1 to 4.2 mm ² on average, the shortest distance between adjacent pattern elements is 10 mm or less, and the pattern element is formed. The value obtained by dividing the blockage rate (percentage) of the fused portion corresponding to the ratio of the total area of the pattern elements included in the repeating pattern to the area of the repeating pattern by the average value of the area of one pattern element is 0.8 to The air filter is 1.2% / mm ² , and the laminated non-woven fabric is a laminated non-woven fabric in which a non-woven fabric for a support and a charged non-woven fabric are bonded, and the non-woven fabric for a support carries tannin. Filter medium for.

According to the present invention, there is provided a filter medium for an air filter which has a low pressure loss, a sufficient adhesive strength of a fused portion, can suppress the occurrence of floating and curling of a laminated non-woven fabric, and has excellent dust collecting performance and anti-allergen performance. be able to.

A state in which the midpoints of each side of the invisible equilateral triangle ABC and the vertices of the equilateral triangle ABC adjacent to each side are aligned so as not to overlap each other (invisible repeating pattern). The figure shown. The figure which showed the arrangement of a pattern element.

Hereinafter, the filter medium for an air filter of the present invention will be described in detail. The filter medium for an air filter of the present invention is a filter medium for an air filter made of a laminated non-woven fabric in which two or more layers of non-woven fabrics are bonded, and the above-mentioned bonding is performed by fusion, and a handle formed in the shape of a fused portion. A plurality of elements form a pattern showing a repeating pattern, and the area of one pattern element is 1 to 4.2 mm ² on average, and the shortest distance between adjacent pattern elements is 10 mm or less. The blockage rate (percentage) of the fused portion corresponding to the ratio of the total area of the pattern elements included in the repeating pattern to the area of the repeating pattern formed by the pattern elements is the average value of the area of one pattern element. The value divided by is 0.8 to 1.2% / mm ² , the laminated non-woven fabric is a laminated non-woven fabric in which a non-woven fabric for a support and a charged non-woven fabric are bonded, and the non-woven fabric for a support supports tannins. It is characterized by being.

The number of laminated non-woven fabrics constituting the filter medium may be at least two layers, and is not particularly limited. However, if the number of laminated fabrics is too large, pressure loss may increase and ventilation as the filter medium may not be ensured. It is preferably 6 layers or less.

Conventionally, as a method of laminating and adhering two or more layers of non-woven fabric, a method of spraying various adhesives and a method of spraying hot melt powder as an adhesive are known, but these methods are adhesives. The generation of odor and outgas can be a problem.

In the present invention, fusion is used as the bonding method. Examples of the fusion include thermal fusion and ultrasonic fusion. The bonding method by fusion is preferable because it does not use an adhesive and does not generate odor or outgas. On the other hand, the fused portion is completely closed and has no air permeability, and its performance as a filter medium is lost. Therefore, it is preferable that the area of the fused portion is as small as possible because the pressure loss is small. On the other hand, if the area of the fused portion is small, the adhesive strength of the fused portion is weakened. In addition, if the area of the non-fused portion is large, floating may occur between the layers of the laminated non-woven fabric, or turning may occur when the filter medium is cut by post-processing, resulting in leakage and other defects of the air filter. .. Therefore, it is necessary to devise the ratio of the area of the fused portion and the non-fused portion, and the shape, size, and arrangement of the fused portion.

Each fused portion is regarded as a "pattern element" constituting the "pattern", and the non-fused portion is regarded as a "background", which will be specifically described below. The "pattern" is formed by forming a set of a plurality of pattern elements to form a repeating pattern. In one of the repeating patterns consisting of a plurality of pattern elements and a background, the ratio of the total area of the plurality of pattern elements to the total area of the repeating pattern is the proportion of the area of the repeating pattern formed by the pattern elements. It corresponds to the ratio of the total area of the pattern elements included in the repeating pattern, and in the present invention, this ratio is referred to as "occlusion rate of the fused portion" or simply "occlusion rate". When one pattern element belongs to a plurality of adjacent patterns in common, the pattern element is considered to belong to a plurality of adjacent patterns at an equal ratio.
The blockage rate is preferably less than 4.0% from the viewpoint of reducing pressure loss. Further, from the viewpoint of ensuring the adhesive strength, the blockage rate is preferably 0.8% or more.

The pattern is composed of one or more "pattern elements", and the pattern elements are surrounded by a non-fused portion. The average value of the area of one pattern element constituting a pattern composed of a plurality of pattern elements is 1 to 4.2 mm ² . If the average value of the area of one handle element is less ^{than 1 mm 2} , the adhesive strength of the fused portion is insufficient, and it cannot be used because it is peeled off when it is used for post-processing of a filter medium or an air filter. On the other hand, in ^{the case of more than 4.2 mm 2} , the pressure loss becomes high due to the high blockage rate. The maximum value of the shortest distance between adjacent handle elements is 10 mm or less. If it exceeds 10 mm, the laminated non-woven fabric in the non-fused portion may be lifted or turned up when the filter medium is cut in the post-processing, resulting in defects such as leaks in the air filter. Further, the minimum value of the shortest distance between adjacent handle elements is preferably 7.5 mm or more. If it is less than 7.5 mm, the pressure loss may increase.

Further, the value obtained by dividing the blockage rate by the average value of the area of one handle element is 0.8 to 1.2% / mm ² . This value indicates the density of pattern elements. If this value is ^{less than 0.8% / mm 2} , the pattern becomes rough, so the spacing between the pattern elements becomes large, and the laminated non-woven fabric in the non-fused part floats up or turns over when the filter medium is cut in post-processing. As a result, defects such as leaks occur in the air filter. On the other hand, when this value exceeds 1.2% / mm ² , the handle becomes dense and the pressure loss becomes high.

The shape of the handle element is not particularly limited, and a plurality of types of shapes may exist. The aspect ratio is large, and an elongated shape is generally preferable from the viewpoint of adhesive strength. Taking a rectangle as an example, the short side is preferably 0.5 to 1 mm, and the long side is preferably 2 to 3 mm. However, if the short side is too small, sufficient adhesive strength may not be obtained.

There are no particular restrictions on the arrangement of pattern elements. If the handle is rough, the pressure loss will be low, but on the contrary, the distance between the handle elements will be large, and the air filter will be liable to be defective. If the handle is dense, the opposite is true. As a preferable specific example of the arrangement of the handle elements that achieves both low pressure loss and as small a distance between the handle elements as possible, the invisible equilateral triangles ABC having a side of 20 to 24 mm should be oriented so as not to overlap each other. In an invisible repeating pattern that is aligned and arranged so that the midpoint of each side of the equilateral triangle ABC and the vertices of adjacent equilateral triangles coincide with each other, the center of gravity G of the equilateral triangle ABC and the vertices A and B , C has a rectangular handle element having a long side of 2 to 3 mm and a short side of 0.5 to 1 mm, and the line and the long side of the rectangle are parallel to each other and the midpoint of the line. An example can be illustrated of a filter medium in which a handle element is present so that the centers of gravity of the rectangles coincide with each other. This is an example, and is not limited to this. Note that FIG. 1 shows a state in which the midpoints of each side of the invisible equilateral triangle ABC and the vertices of the equilateral triangle ABC adjacent to each side are aligned so as not to overlap each other. It is a figure shown. This can be said to be an invisible repeating pattern.

Filter media processing such as bonding of non-woven fabrics by fusion and post-processing of filter media is often performed roll-to-roll with an emphasis on productivity. When the patterns form a repeating pattern, the pattern elements are arranged along the flow direction of the filter media processing. In the post-processing of the filter medium, the filter medium is often slit along the flow direction or cut in the direction perpendicular to the flow direction (width direction). At this time, when the slit wire or the cut wire passes only through the unfused portion of the filter medium, the strip-shaped non-woven fabric may be turned over, which may cause a defect of the air filter. In order to reduce the turning of the strip-shaped non-woven fabric, the handle can be made dense, the distance between the handle elements can be reduced, and the handle element can be increased. There is. When the minimum angle formed by the flow direction of filter media processing and the line obtained by connecting the centers of gravity G of adjacent invisible equilateral triangles ABC is 5 to 25 °, the entire pattern is maintained while maintaining the arrangement of the pattern elements. By tilting from the flow direction, it is possible to obtain an extremely excellent filter medium that can suppress the turning of the strip-shaped non-woven fabric and further suppress the occurrence of defects.

The optimum minimum angle for tilting the entire handle with respect to the flow direction of filter media processing differs depending on the handle. The invisible equilateral triangles ABC having a side of 20 to 24 mm, which are exemplified in the present invention, are arranged so as not to overlap each other, and the midpoints of the respective sides of the equilateral triangle ABC and the adjacent equilateral triangles are arranged. In an invisible repeating pattern arranged so that the vertices match, a long side of 2 to 3 mm and a short side of 0.5 to 1 mm are formed on a line connecting the center of gravity G of the equilateral triangle ABC and each of the vertices A, B, and C. In a filter medium in which a rectangular pattern element exists, the line and the long side of the rectangle are parallel, and the pattern element exists so that the midpoint of the line and the center of gravity of the triangle coincide with each other, the filter medium is processed. The minimum angle formed by the flow direction and the line obtained by connecting the centers of gravity G of adjacent invisible equilateral triangles ABC is preferably 5 to 25 °, more preferably 10 to 20 °.

Examples of the fibers of the non-woven fabric for the support include polyamide fibers, polyester fibers, polyalkylene paraoxybenzoate fibers, polyurethane fibers, polyvinyl alcohol fibers, polyvinylidene chloride fibers, polyvinyl chloride fibers, and polyacrylonitrile fibers. Synthetic fibers such as fibers, polyolefin fibers, phenol fibers; inorganic fibers such as glass fibers, metal fibers, alumina fibers, carbon fibers, activated carbon fibers; wood pulp, bamboo pulp, hemp pulp, kenaf pulp, straw pulp, bagas pulp, Natural fibers such as cotton linter pulp, cotton, wool, and silk; recycled cellulose fibers such as recycled pulp from waste paper and rayon; recycled fibers made from proteins such as collagen, and polysaccharides such as alginic acid, chitin, chitosan, and starch. Can be mentioned. Further, examples thereof include fibers in which performances such as hydrophilicity and flame retardancy are imparted to these fibers. These fibers may be used alone or in combination of two or more. However, in the present invention, since the non-woven fabric for the support and the charged non-woven fabric are bonded by fusion, it is preferable that at least one layer of the non-woven fabric for the support and the charged non-woven fabric contains fibers made of a thermoplastic resin.

The average single fiber diameter of the fibers contained in the non-woven fabric for the support is not particularly limited, but is preferably 6 to 25 μm, more preferably 8 to 20 μm, and further preferably 10 to 18 μm. When the average single fiber diameter is less than 6 μm, the voids between the fibers may become narrow and the pressure loss may increase. On the other hand, when the average single fiber diameter exceeds 25 μm, the gaps between the fibers of the non-woven fabric for the support become large, and the rigidity may be inferior.

The average single fiber diameter in the present invention is calculated by the following procedure. (1) Take a surface photograph of 500 to 1000 times with a microscope, and measure the width of 10 fibers from each sample, for a total of 100 fibers. (2) The average single fiber diameter is calculated from the average value of the measured 100 fibers.

The method for manufacturing the non-woven fabric for the support is not particularly limited, and the web is manufactured by a dry method, a wet fabrication method, a melt blow method, a spunbond method, a flash spinning method, an airlaid method, etc., depending on the purpose and application. A non-woven fabric can be produced by appropriately combining methods for developing strength. As a method for developing the strength of the web, a physical method such as a water flow confounding method, a needle punch method, a stitch bond method; a thermal bonding method such as a thermal bond method; an adhesive method such as a chemical bond method or a resin bond method is used. Method; etc.

Basis weight of the support-body nonwoven is not particularly limited, it is preferably from 25~130g / ^{m 2,} more preferably from 30 to 100 g / ^{m 2,} still to be 40 and 80 g / ^{m 2} preferable. If the basis weight is ^{less than 25 g / m 2} , the strength and rigidity of the filter medium may be insufficient. On the other hand, if the basis weight ^{exceeds 130 g / m 2} , the pressure loss may become too high.

The thickness of the non-woven fabric for the support is preferably 0.2 to 1.4 mm, more preferably 0.3 to 1.2 mm, and further preferably 0.4 to 1.0 mm. If the thickness of the non-woven fabric for the support is less than 0.2 mm, it becomes difficult to perform pleating, and the air filter may be deformed when the pleated air filter is used at a high wind speed. On the other hand, if it exceeds 1.4 mm, it becomes difficult to perform pleating, and the height of the pleats may be uneven.

In the present invention, tannin is used as an anti-allergen agent. Tannins are roughly classified into hydrolyzed type and condensed type tannins. Hydrolyzed tannins are hydrolyzed into polyhydric phenolic acid and polyhydric alcohol by acid, alkali and enzyme, and are localized in dicotyledonous petal flower plants. The polyphenolic acid is classified into gallic acid (gallotannin) and its dimer (elagitannin). Condensed tannin is a product in which a plurality of molecules of catechin (general term for d-catechin, epicatechin, and epigallocatechin) are condensed by a carbon-carbon bond, and is widely distributed in fern plants and monozygotic plants. An example of gallotannin is Rhus chinensis tannin extracted from a gall (Rhus chinensis) formed by infesting the leaves of the genus Rhus chinensis of the family Rhus chinensis. Examples of ellagitannins include geraniin contained in Geraniaceae Geranium thunbergii.

Loading amount of tannin ^is preferably ^{0.5g / m 2 ~10.0g / m 2} , more preferably from ^{1.0g / m 2 ~5.0g / m 2} , 2.0g / m It is more preferably ^{2 to} 4.0 g / m ^{2 or less.} If it is less than 0.5 g / m ² , sufficient anti-allergen performance may not be exhibited, and if it is 10.0 g / m ² or more, anti-allergen performance is exhibited, but a large effect on the supported amount can be expected. However, it also becomes a factor of cost increase.

In the present invention, the method for supporting the tannin on the non-woven fabric for the support is not particularly limited as long as the tannin can be supported on the non-woven fabric for the support as uniformly as possible. An example is a method in which a liquid containing tannin is applied as a coating liquid to a non-woven fabric for a support by coating, spray coating, or the like, and the solvent or dispersion medium is removed by a method such as drying to support the coating.

In the present invention, when the tannin is supported on the non-woven fabric for the support, an amount of binder that does not inhibit the effect of the tannin can be used. Examples of the water-soluble binder include polyvinyl alcohol and starch. Examples of the water-dispersible binder include poly (meth) acrylic acid esters, polyvinyl acetate, polyvinyl chloride, styrene-acrylic resin, vinyl chloride-acrylic resin, silicone resin, styrene-butadiene resin and the like. Be done. The water-dispersible binder may be in the form of an emulsion. Binders are not limited to these. When a binder is used, its content is not particularly limited, but is preferably 50% by mass or less with respect to tannin.

As the charged non-woven fabric, for example, an electret-processed spunbonded non-woven fabric, an electret-processed melt-blown non-woven fabric, or the like is used. An electret-processed melt-blown non-woven fabric is preferable because it can obtain high dust collecting performance. As the resin used for the fiber of the charged non-woven fabric, a resin having a high electric resistance is preferable, and a polyolefin resin such as polypropylene and polyethylene; an aromatic polyester resin such as polyethylene terephthalate; a synthetic polymer material such as a polycarbonate resin; Can be mentioned. Polypropylene, which has a low melting point and is easy to produce a melt-blown non-woven fabric, is more preferable. In addition, various additives may be added to the resin used for the charged non-woven fabric in order to enhance and improve the chargeability, weather resistance, thermal stability, mechanical properties, coloring, surface properties, or other properties. can. In particular, since electret processing is performed, it is preferable to include an electret additive for the purpose of enhancing the chargeability. The electret additive preferably contains at least one electret additive selected from the group consisting of hindered amine compounds and triazine compounds.

The average single fiber diameter of the fibers contained in the charged non-woven fabric is not particularly limited, but is preferably 0.1 to 8 μm, more preferably 0.5 to 6 μm, and further preferably 1 to 4 μm. preferable. When the average single fiber diameter is less than 0.1 μm, the voids between the fibers may become narrow and the pressure loss may increase. On the other hand, when the average single fiber diameter exceeds 8 μm, the gaps between the fibers of the charged non-woven fabric become large, and the dust collecting performance may deteriorate.

Basis weight of the charged non-woven fabric is not particularly limited, is preferably from 5 to 60 g / ^{m 2,} more preferably from 10 to 50 g / ^{m 2,} and still more preferably from 15 to 40 g / ^{m 2.} If the basis weight is ^{less than 5 g / m 2} , the dust collection performance may deteriorate. On the other hand, if the basis weight ^{exceeds 60 g / m 2} , the pressure loss may become too high.

The thickness of the charged non-woven fabric is not particularly limited, but is preferably 0.05 to 1.0 mm, more preferably 0.1 to 0.6 mm, and further preferably 0.15 to 0.5 mm. If the thickness of the charged non-woven fabric is less than 0.05 mm, the dust collection performance may be inferior. On the other hand, if it exceeds 1.0 mm, it becomes difficult to perform pleating, and the height of the pleats may be uneven.

The filter medium for an air filter of the present invention may be used as a veneer, but may also be used in a shape that has been subjected to wavy processing such as a mountain valley-shaped folding process or a corrugated cardboard process, which is generally called pleating. Further, it may be used as a roll filter processed into a winding shape.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to the Examples.

[Manufacturing of filter media for air filters]
<Example 1>
^{A chemical bond non-woven fabric with a grain size of 50 g / m 2} composed of polyester fiber and acrylic resin is used as the non-woven fabric for the support, and tannin (hydrolyzable gallotannin) is supported on the non-woven fabric for the support in an amount of 2.0 g / m. ^It was impregnated to 2 and dried at 120 ° C. to prepare a non-woven fabric for a support carrying tannin. Next, the non-woven fabric for the support and the ^{melt-blown non-woven fabric made of polypropylene of 30 g / m 2} were permanently charged, and the collection efficiency of 0.3 to 0.5 μm counting method under the condition of 5.3 cm / sec was 99.97%. Using the above-mentioned charged non-woven fabric, laminating processing was performed by ultrasonic fusion to obtain a filter medium for an air filter of Example 1.

In the bonding process by ultrasonic fusion, the invisible equilateral triangles ABC are arranged so that they do not overlap each other, and the midpoint of each side of the equilateral triangle ABC and the apex of the adjacent equilateral triangles are aligned. Arranged so as to match (FIG. 1), a rectangular pattern element exists on a line connecting the center of gravity G of the equilateral triangle ABC and each of the vertices A, B, and C, and the line and the long side of the rectangle are parallel to each other. And the pattern element was arranged so that the midpoint of the line and the center of gravity of the rectangle coincided with each other (FIG. 2). The length of one side of the invisible equilateral triangle ABC is 22 mm, the long side of the rectangle is 2 mm, and the short side is 0.5 mm.

<Example 2>
A filter medium for an air filter of Example 2 was obtained in the same manner as in Example 1 except that the length of one side of the invisible equilateral triangle ABC was 20 mm.

<Comparative example 1>
A filter medium for an air filter of Comparative Example 1 was obtained in the same manner as in Example 1 except that the length of one side of the invisible equilateral triangle ABC was 25 mm.

<Comparative example 2>
A filter medium for an air filter of Comparative Example 2 was obtained in the same manner as in Example 2 except that the size of the handle element was 0.5 mm × 1 mm.

<Example 3>
The size of the handle element is 1.2 mm × 3.5 mm, and the length of one side of the invisible equilateral triangle ABC is 24 mm. Obtained.

<Comparative example 3>
A filter medium for an air filter of Comparative Example 3 was obtained in the same manner as in Example 1 except that the size of the handle element was 1 mm × 3 mm and the length of one side of the invisible equilateral triangle ABC was 19 mm.

<Comparative example 4>
A filter medium for an air filter of Comparative Example 4 was obtained in the same manner as in Example 3 except that the size of the handle element was 1.2 mm × 4 mm.

<Comparative example 5>
A filter medium for an air filter of Comparative Example 5 was obtained by the same method as in Example 1 except that a charged non-woven fabric was not used. In Comparative Example 5, ultrasonic fusion was performed only on the non-woven fabric for the support.

<Comparative Example 6>
A filter medium for an air filter of Comparative Example 6 was obtained by the same method as in Example 1 except that tannin was not supported.

<Example 4>
A filter medium for an air filter of Example 4 was obtained in the same manner as in Example 1 except that the non-woven fabric for the support was a chemical bond non-woven fabric having a basis weight of 25 g / m ^{2 composed of polyester fiber and acrylic resin.}

<Example 5>
A filter medium for an air filter of Example 5 was obtained in the same manner as in Example 1 except that the non-woven fabric for the support was a chemically bonded non-woven fabric having a basis weight of 130 g / m ^{2 composed of polyester fiber and acrylic resin.}

The filter media for air filters of Examples 1 to 5 and Comparative Examples 1 to 6 were evaluated by the methods shown below. The evaluation results are shown in Table 1.

[Evaluation method of pressure loss]
The obtained filter medium was cut so as to have a ventilation size of 300 × 300 mm. This cut filter medium was installed in a test wind tunnel where air could be introduced at a constant wind speed so that there would be no leakage from the periphery of the filter medium and no slack would occur. The pressure loss was measured by measuring the differential pressure between the upstream side and the downstream side of the filter medium with a manometer under the condition of a wind speed of 0.5 m / s. From the measured values, it was judged as follows.

◯ (Excellent): The pressure loss is less than 50 Pa.
Δ (Good): The pressure loss is 50 Pa or more and less than 70 Pa.
X (Poor): The pressure loss is 70 Pa or more.

[Evaluation method of dust collection efficiency]
The obtained filter medium was cut so as to have a ventilation size of 300 × 300 mm. This cut filter medium was installed in a test wind tunnel where air could be introduced at a constant wind speed so that there would be no leakage from the periphery of the filter medium and no slack would occur. The number of atmospheric dust particles with a particle size of 0.3 to 0.5 μm on the upstream and downstream sides of the filter medium is measured with a particle counter under the condition of a wind speed of 0.5 m / s, and collected from the measurement results on the upstream and downstream sides. The dust efficiency (%) was calculated. From the calculated value, it was judged as follows.

◯ (Excellent): The dust collection efficiency is 99.97% or more.
Δ (Good): The dust collection efficiency is 99.00% or more and less than 99.97%.
X (Poor): The dust collection efficiency is less than 99.00%.

[Anti-allergen performance]
1. 1. Dispensing of chemicals 1-1. Preparation of allergen solution Purified dania allergen rDerf2 (manufactured by Seikagaku Corporation) was dissolved in PBS (-) to prepare a test allergen solution at 500 ng / ml.

1-2. Preparation of antibody solution Anti-rDerf2 monoclonal antibody 15E11 (manufactured by Seikagaku Corporation) was diluted with PBS (-) to a concentration of 2 μg / ml.

1-3. Preparation of labeled antibody solution Horseradish peroxidase-labeled anti-rDerf2 monoclonal antibody 13A4PO (manufactured by Seikagaku Corporation) was diluted 5000-fold with PBS-T. For PBS-T, 0.5 g of Tween® 20 was dissolved in 1000 ml of PBS (−) and used.

Preparation of 1-4.1% -BSA-PBS (-) 0.2 g of BSA was dissolved in 20 ml of PBS (-) and used.

Preparation of 1-5.0.3 mg / ml-ABTS (Substrate Solution) 3 mg of ABTS was dissolved in 10 ml of 0.3M-Cyrate buffer (pH 4.0), and 10 μl of 30% hydrogen peroxide was added thereto. Used.

2. Test method This test method is a confirmation test that the allergen captured on the filter medium for the air filter is inactivated. The obtained filter media were cut so as to have a size of 2 mm × 4 mm, respectively. This cut filter medium was used as a sample and tested individually. The sample was placed on the bottom of a 48-well plate, 300 μl of allergen solution (500 ng / ml) was added per well, and the mixture was allowed to stand at room temperature for 2 hours. After standing, 50 μl was collected and the concentration of allergen present in the sample was quantified by the sandwich ELISA method. The details of the sandwich ELISA method are as follows.

3. 3. Sandwich ELISA method (1) 50 μl of a coating solution (antibody solution, 2 μg / ml) was added to each well of an ELISA plate and allowed to stand at 4 ° C. overnight.
(2) The coating solution was removed, washed 3 times with 300 μl of PBS (−), 200 μl of 1% −BSA-PBA (−) was added, and the mixture was allowed to stand at room temperature for 1 hour.
(3) The ELISA plate was washed 3 times with 300 μl PBS-T, 50 μl of the allergen solution contacted with the sample for 2 hours was collected and added, and allowed to stand at room temperature for 2 hours.
(4) The ELISA plate was washed 3 times with 300 μl of PBS-T, 50 μl of the labeled antibody solution was added, and the mixture was allowed to stand at room temperature for 2 hours.
(5) After washing the ELISA plate with 300 μl PBS-T three times, 100 μl of 0.3 mg / ml-ABTS was added to develop color at room temperature, and after 20 to 30 minutes of reaction, the mixture was mixed and 405 nm by a microplate reader. The absorbance was measured.
(6) Calculate the purified dania allergen rDerf2 concentration (Ang / ml) in the allergen solution in contact with the sample from the absorbance, and compare this calculated value with the purified dania allergen rDer2 concentration (500 ng / ml) in the initial allergen solution. The allergen removal rate (%; 100 × (500-A) / 500) was determined.

◯ (Good): The allergen removal rate is 80% or more.
X (Poor): The allergen removal rate is less than 80%.

[Evaluation method of adhesive strength]
The obtained filter medium was pleated as a post-processing using a reciprocating pleating machine. The filter medium after pleating was confirmed, and the presence or absence of peeling of the fused portion was confirmed, and the determination was made as follows.

◯ (Good): There is no peeling and there is sufficient adhesive strength.
× (Poor): There is peeling, and the adhesive strength is insufficient.

[Post-workability evaluation method]
In the above-mentioned pleating process, pleating was performed while slitting the width to 186 mm, the pleated ridge height was set to 28 mm, and 41 folds were used as one air filter to cut the filter medium. While holding the pleated filter medium so that the folds are even and fit in a rectangular body of 186 x 200 x 28 mm, apply a hot melt adhesive of ethylene vinyl acetate resin so as to close all the slit end faces of the filter medium. ^{A strip-shaped, 1 mm-thick, 200 g / m 2} polyester spunbonded non-woven fabric having a width of 30 mm and a length of 250 mm, which was applied to a thickness of about 2 mm, was attached to fix the pleated filter medium. The excess spunbonded non-woven fabric was cut so that the outer shape of the air filter was a rectangular parallelepiped of 200 × 200 × 30 mm to obtain an air filter. 100 air filters were prepared. Check the manufactured air filter, and if the filtered material that has been pasted is lifted or turned over, or if the height of the folds of the air filter is uneven, it is considered as "defective", and the defective rate of the air filter is calculated and described below. The post-workability was determined as described above.

◯ (Excellent): The defective rate is 1% or less.
Δ (Good): The defective rate is more than 1% and 5% or less.
× (Poor): The defective rate is more than 5%.

From the comparison of the evaluation results of Examples 1 to 5 and Comparative Examples 1 to 6, it was composed of a laminated non-woven fabric in which two or more layers of non-woven fabric were bonded, and the above bonding was performed by fusion and formed in the shape of the fused portion. A plurality of the patterned elements to be formed form a pattern showing a repeating pattern, and the area of one pattern element is 1 to 4.2 mm ² on average, and the shortest distance between adjacent pattern elements. Is 10 mm or less, and the closure rate (percentage) of the fused portion corresponding to the ratio of the total area of the pattern elements included in the repeating pattern to the area of the repeating pattern formed by the pattern elements is the area of one pattern element. The value divided by the average value of is 0.8 to 1.2% / mm ² , the laminated non-woven fabric is a laminated non-woven fabric in which a non-woven fabric for a support and a charged non-woven fabric are bonded, and the non-woven fabric for a support is tannin. It can be seen that the filter medium for an air filter carrying the above is a filter medium having an excellent balance between pressure loss and adhesive strength, excellent dust collection efficiency and anti-allergen performance, and a low defect rate.

From the comparison between Example 2 and Comparative Example 2, it can be seen that when the average value of the area of one handle element is less ^{than 1 mm 2} , peeling of the fused portion occurs in the post-processing and the adhesive strength is inferior.

From the comparison of the evaluation results of Example 3 and Comparative Example 4, ^{it can be seen that when the average value of the area of one handle element exceeds 4.2 mm 2} , the fused portion is large and the pressure loss is high.

From the comparison of the evaluation results between Example 3 and Comparative Example 1, when the value obtained by dividing the blockage rate by the average value of the area of one handle element is ^{less than 0.8% / mm 2} , the patterns are sparse and the adjacent patterns are adjacent to each other. It can be seen that the maximum value of the shortest distance of the element exceeds 10 mm, the filter medium floats and turns over in the post-processing, and the defect rate increases.

From the comparison of the evaluation results between Example 2 and Comparative Example 3, when the value obtained by dividing the blockage rate by the average value of the area of one handle element exceeds 1.2% / mm ² , the handle becomes dense and the pressure loss occurs. It turns out that it will be higher.

From the comparison of the evaluation results of Example 1 and Comparative Example 5, it can be seen that the dust collection efficiency is significantly inferior when the charged non-woven fabric is not provided.

From the comparison of the evaluation results of Example 1 and Comparative Example 6, it can be seen that the anti-allergen performance is significantly inferior when it does not have tannin.

The present invention is used for a filter medium for an air filter used in an air conditioner or the like.

Claims (1)

A filter medium for an air filter made of a laminated non-woven fabric in which two or more layers of non-woven fabric are bonded, and a plurality of pattern elements formed in the shape of the fused portion are formed by fusion. The area of one pattern element is 1 to 4.2 mm ² on average, the shortest distance between adjacent pattern elements is 10 mm or less, and the pattern element is formed. The value obtained by dividing the blockage rate (percentage) of the fused portion corresponding to the ratio of the total area of the pattern elements included in the repeating pattern to the area of the repeating pattern by the average value of the area of one pattern element is 0.8 to The air filter is 1.2% / mm ² , and the laminated non-woven fabric is a laminated non-woven fabric in which a non-woven fabric for a support and a charged non-woven fabric are bonded, and the non-woven fabric for a support carries tannin. Filter medium for.

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