CN113660991A

CN113660991A - Filter material for air cleaner

Info

Publication number: CN113660991A
Application number: CN202080026035.6A
Authority: CN
Inventors: 佐藤史洋; 松冈昌伸; 保坂健一
Original assignee: Mitsubishi Paper Mills Ltd
Current assignee: Mitsubishi Paper Mills Ltd
Priority date: 2019-03-29
Filing date: 2020-03-24
Publication date: 2021-11-16
Also published as: JPWO2020203480A1; WO2020203480A1; JP6824476B1

Abstract

A filter medium for an air cleaner, comprising 2 or more layers of nonwoven fabrics bonded together, wherein the bonding is performed by fusion bonding, a plurality of pattern units formed in the shape of a fused portion form a pattern in a group to form a repeating pattern, and the area of 1 pattern unit is 1 to 4.2mm on average²The shortest distance between adjacent pattern units is 10mm or less, and the value obtained by dividing the blockage rate (percentage) of the welded part by the average value of the areas of 1 pattern unit is 0.8-1.2%/mm²The blocking ratio of the welded portion corresponds to a ratio of a total area of the pattern cells included in the repetitive pattern among the areas of the repetitive pattern formed by the pattern cells.

Description

Filter material for air cleaner

Technical Field

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

Background

In recent years, due to changes in living environments, increased health consciousness, and the like, air conditioning equipment such as air conditioners, air purifiers, humidifiers, and dehumidifiers have been widely used in all living spaces such as houses, offices, factories, and automobiles. In these air conditioners, various air cleaners are often used to obtain purified air. These air conditioning equipment and air cleaner are required to have high functionality and multiple functions year by year.

Air cleaners are required to have a dust collecting function and a deodorizing function. In addition, a function of removing a specific harmful gas, an antibacterial function, an antiviral function, an anti-allergen function, and the like are required. The air cleaner can be used for performing each function independently, and can be mounted on an air conditioner by combining a plurality of air cleaners for multi-functionalization as needed. However, it is generally difficult to occupy a large space for mounting the air cleaner, and therefore, there is a need for an air cleaner that is multifunctional by integrating a plurality of functions into 1 air cleaner.

There are various types of air cleaners, and filter media for air cleaners made of nonwoven fabrics are widely used, and various nonwoven fabrics can be selected and used depending on the application and performance. Various nonwoven fabrics are combined with each other for high performance and multi-performance, and further combined with different materials to form a filter medium. As a combination method, a method of laminating a plurality of nonwoven fabrics and raw materials, bonding them together, and adhering them is often used.

Various adhesives are used as a method for laminating and bonding nonwoven fabrics to form a laminated nonwoven fabric, but in applications where odor or exhaust gas generated from the adhesive becomes a problem, the adhesive may be unpleasant. As another method, there is a method of bonding by welding, and since an adhesive is not used, odor or exhaust gas is not generated, which is preferable. Examples of the welding method include thermal welding and ultrasonic welding.

When the nonwoven fabric is bonded by welding, the welded portion of the nonwoven fabric is closed without air permeability, and the performance as a filter medium is lost. Therefore, a mode in which the area of the welded portion is as small as possible is preferable as the filter medium because the pressure loss is small. On the other hand, if the area of the welded portion is small, the adhesive strength of the welded portion becomes weak. Further, if the area of the non-welded portion is large, the layers of the laminated nonwoven fabric may be lifted, or when the filter medium is cut in a subsequent process, the nonwoven fabric may be rolled up between the non-welded portions, which may cause a problem of a failure of the air cleaner such as leakage. Therefore, there is a problem of obtaining an excellent filter medium which has a low pressure loss, has a sufficient bonding strength at the welded portion, and can suppress the occurrence of a defect in the air cleaner due to the lifting and rolling of the laminated nonwoven fabric.

Patent document 1 discloses a regenerated cellulose nonwoven fabric sheet comprising a heat-fusible cellulose fiber containing hydroxymethyl xanthate formed from viscose, a web formed by papermaking of the heat-fusible cellulose fiber in a wet process, and an embossed web formed by heat-fusing the webs to each other while pressing the webs with an embossing roller, wherein the pattern transferred to the embossed web by the embossing roller when pressing the web is composed of a combination of a linear 1 st groove and a linear 2 nd groove, the end of the 2 nd groove is arranged at a right angle near a middle position in the longitudinal direction of the 1 st groove, and the end of the 1 st groove is arranged at a right angle near a middle position in the longitudinal direction of the 2 nd groove, thereby, the 1 st groove portion and the 2 nd groove portion are alternately and continuously arranged on the entire surface of the embossed web. In addition, patent document 1 proposes the following pattern when a non-welded portion is regarded as a background and an embossed portion (welded portion) is regarded as a pattern: in the lattice points of the square lattice, the welding portions such as rectangles are arranged with the direction of 90 ° changed with respect to the adjacent welding portions. However, when the pattern of patent document 1 is applied to a filter medium in which nonwoven fabrics are laminated, if the lattice is small, the clogging rate is high and the pressure loss is high, whereas if the lattice is large, the laminated nonwoven fabric is liable to be lifted and curled, and improvement is required.

Patent document 2 discloses an outer layer nonwoven fabric used for an absorbent article such as a disposable diaper, which is disclosed in the following pattern: the welding device has a plurality of welding parts which are repeatedly arranged with regularity in a manner of contacting with an imaginary circle. However, non-welded portions corresponding to the virtual circle diameter are generated, and when the pattern of the absorbent article is applied to a filter medium in which nonwoven fabrics are laminated, the laminated nonwoven fabric is likely to be lifted or rolled up, and improvement is required.

Documents of the prior art

Patent document

Patent document 1: japanese utility model registration No. 3180626

Patent document 2: international publication No. 2018/123638 handbook

Disclosure of Invention

Problems to be solved by the invention

The invention provides a filter medium for an air cleaner, which has low pressure loss, sufficient bonding strength of a welding part and can inhibit the generation of the tilting and rolling of a laminated non-woven fabric.

Other objects and advantages of the present invention will become apparent from the following description.

Means for solving the problems

The problem of the present invention can be solved by the following method.

＜1＞

A filter medium for an air cleaner, comprising a laminated nonwoven fabric formed by laminating 2 or more layers of nonwoven fabrics, wherein the lamination is performed by fusion bonding, a plurality of pattern units formed in the shape of a fusion-bonded portion form a pattern having a repeating pattern, and the area of 1 pattern unit is 1 to 4.2mm on average²The shortest distance between adjacent pattern units is 10mm or less, and the value obtained by dividing the blockage rate (percentage) of the welded part by the average value of the areas of 1 pattern unit is 0.8-1.2%/mm²The blocking ratio of the welded portion corresponds to a ratio of a total area of the pattern cells included in the repetitive pattern among the areas of the repetitive pattern formed by the pattern cells.

＜2＞

According to the filter medium for an air cleaner of < 1 >, the repeating pattern of the pattern unit is formed as follows: in an invisible repeating pattern in which invisible triangles ABC having one side of 20-24 mm are arranged so that the direction is uniform and does not overlap each other so that the midpoint of each side of the regular triangle ABC coincides with each vertex of a triangle ABC adjacent to each side, rectangular pattern elements having a long side of 2-3 mm and a short side of 0.5-1 mm are present on a straight line connecting the center of gravity G of the regular triangle ABC and each vertex A, B, C, such that the straight line is parallel to the long side of the rectangle and the midpoint of the straight line coincides with the center of gravity of the rectangle.

＜3＞

The filter medium for an air cleaner according to < 2 >, wherein a line connecting the centers of gravity G of the adjacent 2 regular triangles ABC forms a minimum angle of 5 to 25 degrees with respect to the flow direction of the filter medium processing.

＜4＞

The filter medium for an air cleaner as described in any one of < 1 > to < 3 >, wherein the laminated nonwoven fabric is a bonded nonwoven fabric obtained by bonding an electrically charged nonwoven fabric and a protective nonwoven fabric, and the adsorbent is sealed between the support nonwoven fabric and the bonded nonwoven fabric by a thermoplastic adhesive.

＜5＞

The filter medium for an air cleaner as described in any one of < 1 > to < 3 >, wherein the laminated nonwoven fabric is a laminated nonwoven fabric in which a support nonwoven fabric and an electrically charged nonwoven fabric are laminated.

＜6＞

The filter medium for an air cleaner according to < 5 >, wherein the adsorbent is carried on the nonwoven fabric as the support.

＜7＞

The filter medium for an air cleaner as described in any one of < 1 > to < 3 >, wherein the laminated nonwoven fabric is a laminated nonwoven fabric in which an electrically charged nonwoven fabric, a protective nonwoven fabric and a support nonwoven fabric are laminated, and the protective nonwoven fabric is disposed on a side in contact with an external air.

Effects of the invention

According to the filter medium for an air cleaner of the present invention, the pressure loss is low, the adhesive strength of the welded portion is sufficient, and the occurrence of the lifting and rolling of the laminated nonwoven fabric can be suppressed.

Drawings

Fig. 1 is a diagram showing a state (invisible repetitive pattern) in which the directions are aligned so that the midpoints of the sides of the invisible regular triangle ABC and the vertices of the adjacent regular triangle ABC of each side are aligned and are arranged so as not to overlap each other.

Fig. 2 is a diagram showing the arrangement of pattern cells.

Detailed Description

Air filter of the inventionA filter medium for an air cleaner comprising a laminated nonwoven fabric comprising 2 or more layers of nonwoven fabrics laminated together, wherein the lamination is performed by fusion bonding, a plurality of pattern elements formed in the shape of a fused portion form a pattern in a set of a repeating pattern, and the area of 1 pattern element is 1 to 4.2mm on average²The shortest distance between adjacent pattern units is 10mm or less, and the value obtained by dividing the blockage rate (percentage) of the welded part by the average value of the areas of 1 pattern unit is 0.8-1.2%/mm²The blocking ratio of the welded portion corresponds to a ratio of a total area of the pattern cells included in the repetitive pattern among the areas of the repetitive pattern formed by the pattern cells.

The number of layers of the nonwoven fabric constituting the filter medium is not particularly limited, but is preferably 6 or less layers because an excessive number of layers increases the pressure loss and may not ensure ventilation as the filter medium.

As a bonding method for bonding a nonwoven fabric having 2 or more layers, a method of spraying various adhesives and a method of spreading a hot-melt adhesive powder as an adhesive have been known in the related art, but these methods have a problem that odor and exhaust gas are generated from the adhesive.

In the present invention, welding is used as the bonding method. Examples of the welding include thermal welding and ultrasonic welding. The method of bonding by fusion bonding is preferable because it does not use an adhesive, and therefore, odor and exhaust gas are not generated. On the other hand, the welded portion is completely closed, and the air permeability is lost, and the performance as a filter medium is lost. Therefore, a mode in which the area of the welded portion is as small as possible is preferable because the pressure loss is small. On the other hand, if the area of the welded portion is small, the adhesive strength of the welded portion becomes weak. Further, if the area of the non-welded portion is large, the layers of the laminated nonwoven fabric may be warped, or the filter medium may be rolled up when being cut in a post-process, resulting in a defect of the air cleaner such as occurrence of leakage. Therefore, it is necessary to plan the ratio of the areas of the welded portion to the non-welded portion, and the shape, size, and arrangement of the welded portion.

Hereinafter, each welded portion will be referred to as a "pattern unit" constituting a "pattern", and a non-welded portion will be referred to as a "background", specifically. The "pattern" is formed by a plurality of pattern units in a set, constituting a repeating pattern. In the present invention, the ratio of the total area of the plurality of pattern units in 1 repeating pattern composed of the plurality of pattern units and the background to the total area of the 1 repeating pattern corresponds to the ratio of the total area of the pattern units included in the repeating pattern to the area of the repeating pattern formed of the pattern units, and this ratio is referred to as "the blocking ratio of the welded portion" or simply "the blocking ratio". When 1 pattern cell belongs to a plurality of adjacent patterns in common, the pattern cells are considered to belong to the plurality of adjacent patterns at the same ratio.

From the viewpoint of reducing the pressure loss, the clogging ratio is preferably less than 4.0%. From the viewpoint of securing the adhesive strength, the blocking ratio is preferably 0.8% or more.

The pattern is composed of 1 or more "pattern units" surrounded by non-welded portions. The average value of the areas of 1 pattern unit in the pattern composed of a plurality of pattern units is 1-4.2 mm². The average of the areas of 1 pattern unit is less than 1mm²In the case of using the filter, the adhesive strength of the welded portion is insufficient, and the filter cannot be used because the filter is peeled off during the post-processing of the filter material and the use in an air cleaner. On the other hand, higher than 4.2mm²In this case, the clogging rate becomes high, resulting in high pressure loss. The maximum value of the shortest distance between adjacent pattern cells is 10mm or less. If the thickness is more than 10mm, the laminated nonwoven fabric at the non-welded portion is lifted, or the laminated nonwoven fabric is rolled up when the filter medium is cut in post-processing, and air filter defects such as leakage occur. The minimum value of the shortest distance between adjacent pattern cells is preferably 7.5mm or more. If the thickness is less than 7.5mm, the pressure loss may be high.

The average value of the area of 1 pattern unit divided by the blocking rate is 0.8 to 1.2%/mm². This value represents the density of pattern cells. This value is less than 0.8%/mm²In time, the patterns become sparse, and thus the pattern sheetThe element interval becomes large, and defects of the air cleaner such as the laminated nonwoven fabric in the non-welded part being warped, or the laminated nonwoven fabric being rolled up and leaking when the filter medium is cut in the post-processing occur. On the other hand, this value is higher than 1.2%/mm²In this case, the pattern becomes dense, and thus the pressure loss becomes high.

The shape of the pattern unit is not particularly limited, and various shapes may be present. From the viewpoint of bonding strength, a substantially elongated shape having a large aspect ratio is preferable. When a rectangle is taken as an example, the short side is preferably 0.5 to 1mm, and the long side is preferably 2 to 3 mm. However, if the short side is too small, sufficient bonding strength may not be obtained.

The arrangement of the pattern units is not particularly limited. If the pattern is sparse, the pressure loss becomes low, but on the contrary, the interval of the pattern cells becomes large, and the air cleaner failure is likely to occur. If the pattern is tight, the opposite is true. As a specific example of preferable arrangement of pattern cells that can achieve both reduction in pressure loss and reduction in pattern cell spacing as much as possible, the following filter media can be exemplified: in an invisible repeating pattern in which invisible regular triangles ABC having one side of 20-24 mm are oriented in a uniform manner so as not to overlap each other and the midpoints of the sides of the regular triangles ABC are aligned with the vertices of adjacent regular triangles, rectangular pattern elements having a long side of 2-3 mm and a short side of 0.5-1 mm are present on a line connecting the center of gravity G of the regular triangle ABC and the vertices A, B, C, and the pattern elements are present as follows: the line is parallel to the long sides of the rectangle, and the midpoint of the line is coincident with the center of gravity of the rectangle. This is an example, and is not limited thereto. Fig. 1 is a diagram showing a state in which the directions are aligned so that the midpoints of the sides of the invisible regular triangle ABC and the vertices of the regular triangle ABC adjacent to each side do not overlap each other. This is also referred to as an invisible repeating pattern.

In the processing of a filter medium such as bonding of a nonwoven fabric by fusion and post-processing of a filter medium, roll-to-roll processing is often performed with importance placed on productivity. When the pattern forms a repeating pattern, pattern units are arranged along the direction of processing of the filter medium. In the post-processing of the filter medium, the filter medium is often slit in the flow direction, or cut in a direction (width direction) perpendicular to the flow direction. In this case, the cut line and the cut line may cause the ribbon-shaped nonwoven fabric to be wound up and cause a failure in the air cleaner only when the non-welded portion of the filter medium passes through. In order to reduce the rolling of the tape-shaped nonwoven fabric, the pattern can be made dense, the interval between the pattern cells can be made small, or the pattern cells can be made large. When the minimum angle formed by the flow of the filter medium processing and the line connecting the centers of gravity G of the adjacent invisible regular triangles ABC is 5-25 degrees, the entire pattern is inclined from the flow direction while maintaining the arrangement of the pattern units, and thus a very excellent filter medium capable of suppressing the rolling-up of the belt-shaped nonwoven fabric and further suppressing the occurrence of defects can be obtained.

The optimum minimum angle at which the entire pattern is inclined with respect to the flow direction of the filter medium processing differs depending on the pattern. In the filter medium exemplified in the present invention, in an invisible repeating pattern in which invisible equilateral triangles ABC having one side of 20 to 24mm are arranged in a uniform direction so as not to overlap each other and the midpoints of the sides of the equilateral triangles ABC are arranged so as to coincide with the vertexes of adjacent equilateral triangles, pattern elements of rectangles having long sides of 2 to 3mm and short sides of 0.5 to 1mm are present on a line connecting the center of gravity G and each vertex A, B, C of the equilateral triangles ABC, and the pattern elements are present so that the line is parallel to the long sides of the rectangles and the midpoints of the lines coincide with the center of gravity of the rectangles, the minimum angle formed by the flow direction of processing of the filter medium and the line connecting the centers of gravity G of the adjacent invisible equilateral triangles is preferably 5 to 25 °, more preferably 10 to 20 °.

Examples of the fibers of the nonwoven fabric include the following: synthetic fibers such as polyamide-based fibers, polyester-based fibers, polyalkylene parahydroxybenzoate-based fibers, polyurethane-based fibers, polyvinyl alcohol-based fibers, polyvinylidene chloride-based fibers, polyvinyl chloride-based fibers, polyacrylonitrile-based fibers, polyolefin-based fibers, and phenol-based fibers; inorganic fibers such as glass fibers, metal fibers, alumina fibers, carbon fibers, and activated carbon fibers; natural fibers such as wood pulp, bamboo pulp, hemp pulp, kenaf pulp, straw pulp, bagasse pulp, cotton linter pulp, cotton, wool, silk and the like; recycled cellulose fibers such as recycled pulp and rayon; regenerated fibers made of proteins such as collagen, polysaccharides such as alginic acid, chitin, chitosan, and starch. Further, fibers having a hydrophilic function, a flame retardant function, and the like are given to these fibers. These fibers may be used alone, or 2 or more kinds may be used in combination. However, since the nonwoven fabric of the present invention is bonded by fusion bonding, it is preferable that at least 1 layer of the nonwoven fabric contains fibers made of a thermoplastic resin.

The method for producing the nonwoven fabric is not particularly limited, and the nonwoven fabric can be produced by a method of forming a web by a dry method, a wet method, a melt-blowing method, a spunbond method, a flash-spinning method, an air-laying method, or the like, and appropriately combining the methods to exhibit web strength, depending on the purpose and application. Examples of the method for expressing the net strength include the following methods: physical methods such as a spunlace method, a needle punching method, a stitch knitting method and the like; a bonding method using heat, such as a thermal bonding method; a chemical bonding method, a resin bonding method, and the like.

The basis weight of the nonwoven fabric is not particularly limited, but is preferably 5 to 300g/m². Higher than 300g/m²In this case, the pressure loss increases, and ventilation as a filter medium may not be ensured. Further, less than 5g/m²In this case, the adhesive may not be used for reasons such as insufficient strength required for bonding.

Further, the nonwoven fabric may be provided with various functions as follows, as required: antibacterial, antifungal, antiviral, antiallergic, insect-proofing, insecticidal, deodorant, aromatic, temperature-sensitive, heat-retaining, heat-releasing, heat-absorbing, waterproof, water-resistant, water-repellent, hydrophobic, hydrophilic, dehumidifying, humidity-conditioning, moisture-absorbing, oil-repellent, lipophilic, oil-absorbing, evaporable or slow-releasing of water or volatile agents, and the like.

Specific examples of the filter medium for an air cleaner including a laminated nonwoven fabric in which 2 or more layers of nonwoven fabrics are bonded together by welding will be described below, but the present invention is not limited to these specific examples.

< filter material A >

The filter material a is a filter material for an air cleaner as follows: the laminated nonwoven fabric is a bonded nonwoven fabric obtained by bonding an electrically charged nonwoven fabric and a protective nonwoven fabric, and an adsorbent is sealed between the support nonwoven fabric and the bonded nonwoven fabric by a thermoplastic adhesive.

The fibers of the nonwoven fabric for support in the filter medium a include the fibers of the nonwoven fabric. The average single fiber diameter of the fibers contained in the nonwoven fabric for a support in the filter medium A is not particularly limited, but is preferably 6 to 25 μm, more preferably 8 to 20 μm, and still more preferably 10 to 18 μm. When the average filament diameter is less than 6 μm, the voids between the fibers may be narrowed, and the pressure loss may be increased. On the other hand, if the average single fiber diameter is more than 25 μm, the voids between the fibers of the nonwoven fabric for a support become large, and the enclosed adsorbent may fall off.

The average single fiber diameter of the present invention is calculated by the following procedure. (1) The microscope takes 500 to 1000 times surface photographs, and the width of 100 fibers is measured in total from each sample per 10. (2) From the average of the measured values of 100, the average single fiber diameter was calculated.

The basis weight of the nonwoven fabric for support in the filter medium A is not particularly limited, but is preferably 10 to 300g/m²More preferably 30 to 150g/m²More preferably 40 to 100g/m². The gram weight is less than 10g/m²In this case, the strength and rigidity of the filter medium may be insufficient. On the other hand, the grammage is higher than 300g/m²In this case, the pressure loss may become excessively high.

The method for producing the support nonwoven fabric and the protective nonwoven fabric in the filter medium a may be the same as the method for producing the nonwoven fabric. The support nonwoven fabric and the protective nonwoven fabric in the filter medium a may be provided with the above-described various functions as needed.

As the charged nonwoven fabric in the filter medium a, for example, a spunbond nonwoven fabric processed with an electret, a meltblown nonwoven fabric processed with an electret, or the like can be used. The melt-blown nonwoven fabric subjected to electret processing is preferable in view of obtaining high dust collecting performance. The resin used for the fibers of the charged nonwoven fabric is preferably a resin having a high specific resistance, and examples thereof include: polyolefin resins such as polypropylene and polyethylene; aromatic polyester resins such as polyethylene terephthalate; synthetic polymer materials such as polycarbonate resins. More preferably polypropylene having a low melting point and capable of easily producing a melt-blown nonwoven fabric. In addition, various additives can be added to the resin used for the charged nonwoven fabric in order to enhance and improve the charging property, weather resistance, thermal stability, mechanical properties, coloring, surface properties, and other properties. In particular, for electret processing, it is preferable to contain an electret additive for the purpose of enhancing the charging property. 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 nonwoven fabric in the filter medium A is not particularly limited, but is preferably 0.1 to 8 μm, more preferably 0.5 to 6 μm, and still more preferably 1 to 4 μm. When the average filament diameter is less than 0.1. mu.m, the voids between the fibers may be narrowed, resulting in a high pressure loss. On the other hand, if the average single fiber diameter is more than 8 μm, the gaps between the fibers of the charged nonwoven fabric become large, and the dust collecting performance may be lowered.

The basis weight of the charged nonwoven fabric in the filter medium A is not particularly limited, but is preferably 5 to 60g/m²More preferably 10 to 50g/m²More preferably 15 to 40g/m². The gram weight is less than 5g/m²In some cases, dust collecting performance may be reduced. On the other hand, the grammage is higher than 60g/m²In this case, the pressure loss may become excessively high.

The thickness of the charged nonwoven fabric in the filter medium A is not particularly limited, but is preferably 0.05 to 1.0mm, more preferably 0.1 to 0.6mm, and still more preferably 0.15 to 0.5 mm. If the thickness of the charged nonwoven fabric is less than 0.05mm, dust collecting performance may be poor. On the other hand, if the thickness is more than 1.0mm, the crumpling process may be difficult, and the height of the crumpled convex fold may not be uniform.

The protective nonwoven fabric fibers in the filter medium a may be the above-mentioned nonwoven fabric fibers. The average single fiber diameter of the fibers contained in the protective nonwoven fabric in the filter medium A is not particularly limited, but is preferably 6 to 20 μm, more preferably 8 to 16 μm, and still more preferably 10 to 15 μm. When the average filament diameter is less than 6 μm, the voids between the fibers may be narrowed, and the pressure loss may be increased. On the other hand, if the average single fiber diameter is more than 20 μm, the bonding points between the fibers of the protective nonwoven fabric decrease, the strength of the protective nonwoven fabric itself decreases, and the bonding process may not be performed.

The grammage of the protective nonwoven fabric in the filter medium A is not particularly limited, but is preferably 5 to 60g/m²More preferably 8 to 40g/m²More preferably 10 to 30g/m². The gram weight is less than 5g/m²In this case, the protective nonwoven fabric may not have sufficient strength and may not be completely bonded to the charged nonwoven fabric. On the other hand, the grammage is higher than 60g/m²In this case, the pressure loss may become excessively high.

The adsorbent in filter a is used mainly for the purpose of removing offensive odor. Specifically, the following can be mentioned: adsorbents such as activated carbon, impregnated activated carbon, natural and synthetic zeolites, sepiolite, activated alumina, activated clay, ion exchange resins, iron ascorbate, iron phthalocyanine derivatives, and the like; low-temperature oxidation catalysts such as manganese-based oxides and perovskite-type catalysts; photocatalysts such as titanium oxide and zinc oxide; catechin, tannin, flavone, etc.; iron-based compounds such as iron oxide; zinc oxide, magnesium oxide, silica-zinc oxide complexes, silica-alumina zinc oxide complexes, manganese dioxide, complex phyllosilicates, cyclodextrins, mixtures of ascorbic acid and ferrous salts, mixtures of vitamin B groups and phosphates, and the like. The shape of these adsorbents is not particularly limited, but the adsorbents are preferably in the form of particles, and the specific surface area is preferably 50 to 2000m²(ii) in terms of/g. For example, in the case of activated carbon, the dust removal performance and the number of days of endurance were determined by the calculation of the dust removal performance and the calculation of the number of days of endurance established in JEM 1467-1995 and the like. These adsorbents may be used in combination of a plurality of kinds as required, or may be used as a mixed adsorbent by compounding these adsorbents.

The amount of the adsorbent to be sealed in the filter medium A is not particularly limited, but is preferably 30 to 500g/m²More preferably 50 to 400g/m²More preferably 100 to 300g/m². The sealing amount is less than 30g/m²In some cases, sufficient deodorizing performance may not be obtained. On the other hand, higher than 500g/m²In this case, the pressure loss may be too high.

The thermoplastic adhesive in the filter medium a is mainly composed of a thermoplastic resin, and examples of the thermoplastic resin include ethylene-vinyl acetate copolymers or modified products thereof, ethylene acrylic acid copolymers, ionomers, polyamides, polyesters, polyethylene, polypropylene, polyurethane-based resins, and the like.

The softening point or melting point of the thermoplastic adhesive is not particularly limited, and may be appropriately selected in consideration of the post-processing conditions of the filter medium, the use environment temperature, the heat resistance of the nonwoven fabric for support, the bonded nonwoven fabric, the adsorbent, and the like.

The adsorbent or thermoplastic binder in the filter medium a is preferably in the form of powder, granules, whiskers, or short fibers, and the distribution of the adsorbent in the filter medium can be made uniform.

When the adsorbent or thermoplastic binder in the filter medium a is in the form of powder or granule, the particle size thereof is preferably 10 to 100 mesh, more preferably 15 to 90 mesh, and still more preferably 20 to 80 mesh. If the particle size is less than 10 mesh, the adsorbent may be cracked when pressurized, or the bonding points between the support nonwoven fabric and the bonded nonwoven fabric may be uneven, while if the particle size is more than 100 mesh, the adsorbent may be separated from the mesh of the filter medium.

The mass ratio (S/T) of the adsorbent (S) to the thermoplastic adhesive (T) in the filter medium A is preferably 0.3 to 4, more preferably 0.4 to 2.8, and still more preferably 0.6 to 2.5. If the mass ratio (S/T) is less than 0.3, the thermoplastic adhesive covers the surface of the adsorbent, so that the deodorizing performance is significantly reduced and the air permeability of the filter medium may be impaired. On the other hand, if the mass ratio (S/T) is greater than 4, the adhesive strength is insufficient, and the support nonwoven fabric and the bonded nonwoven fabric may be easily peeled off or the adsorbent may be easily peeled off.

In the filter medium a, an adsorbent and a thermoplastic adhesive are dispersed on a nonwoven fabric for a support, and the nonwoven fabric is laminated thereon, and the adhesiveness of the thermoplastic adhesive is developed by heating to integrate them to produce a filter medium. Preferably, the charged nonwoven fabric side of the bonded nonwoven fabric is in contact with the adsorbent. When the adsorbent and the thermoplastic adhesive are dispersed on the nonwoven fabric for support, they may be dispersed separately, but if it is desired to have no particular influence on the deodorizing property, it is preferable to mix and disperse them in advance. Examples of the method of spreading include spraying and die coating in which the dispersion is dispersed as water dispersion, spreading by blowing air while freely falling from the lower part of a hopper, and the like.

In the filter medium a, heating in the step of sealing the adsorbent is not particularly limited, but basically, the filter medium a is roughly classified into 2 types. That is, one is a method in which a thermoplastic adhesive, preferably an adsorbent and a thermoplastic adhesive are dispersed in a nonwoven fabric for a support and then heated. Another method is a method in which an adsorbent and a thermoplastic adhesive are dispersed in a nonwoven fabric for a support, and the bonded nonwoven fabrics are superposed and then heated. In the present invention, any heating method may be used depending on the purpose, and two heating methods may be used in combination.

In the filter medium a, the nonwoven fabric for support and the bonded nonwoven fabric are laminated and then integrated by pressurization, and for example, a method of passing between pressurized rollers can be used. The degree of pressurization may be appropriately set in consideration of the adhesive strength, crushing of the adsorbent, influence on the air permeability, and the like.

< filter material B >

The filter material B is a filter material for an air cleaner as follows: the laminated nonwoven fabric is a laminated nonwoven fabric in which a support nonwoven fabric and an electrically charged nonwoven fabric are laminated.

In the filter material B, the nonwoven fabric for a support preferably has a grammage of 20 to 120g/m²More preferably 30 to 100g/m²More preferably 40 to 80g/m². The gram weight is less than 20g/m²In the case of this, the strength and rigidity of the filter medium are insufficient, and the filter medium may be deformed when the pleating process is performed. On the other hand, the grammage is higher than 120g/m²In this case, the pressure loss may become excessively high.

The method of bonding the fibers of the nonwoven fabric for support in the filter medium B is preferably a chemical bonding method or a thermal bonding method. In the needle punching method and the spunlacing method, strength is expressed by three-dimensionally interlacing fibers with needles or water flows, and since the fibers are relatively soft and have poor stiffness, when corrugation processing is performed, if the ventilation amount is increased, the filter medium may be deformed.

The fibers of the nonwoven fabric for support in the filter medium B may be the same fibers as those of the nonwoven fabric. The average single fiber diameter of the fibers contained in the nonwoven fabric for a support is not particularly limited, but is preferably 6 to 25 μm, more preferably 8 to 20 μm, and still more preferably 10 to 18 μm. When the average filament diameter is less than 6 μm, the voids between the fibers may be narrowed, and the pressure loss may be increased. On the other hand, if the average single fiber diameter is more than 25 μm, the gaps between the fibers of the nonwoven fabric for a support become large, and the stiffness may be poor.

The nonwoven fabric for a support in the filter medium B may be added with the above-described various functions as needed.

The charged nonwoven fabric in the filter medium B may be the charged nonwoven fabric in the filter medium a.

< filter medium C >

The filter medium C is a filter medium for an air cleaner as follows: the laminated nonwoven fabric is a laminated nonwoven fabric in which a support nonwoven fabric and an electrically charged nonwoven fabric are laminated, and the support nonwoven fabric carries an adsorbent.

The fibers of the nonwoven fabric for support in the filter medium C include the fibers of the nonwoven fabric. The average single fiber diameter of the fibers contained in the nonwoven fabric for a support in the filter medium C is not particularly limited, but is preferably 6 to 25 μm, more preferably 8 to 20 μm, and still more preferably 10 to 18 μm. When the average filament diameter is less than 6 μm, the voids between the fibers may be narrowed, and the pressure loss may be increased. On the other hand, if the average single fiber diameter is more than 25 μm, the gaps between the fibers of the nonwoven fabric for a support are large, and the stiffness may be poor.

The method for producing the nonwoven fabric for a support in the filter medium C may be the same as the method for producing the nonwoven fabric.

Nonwoven fabric for support in filter medium CHeavy, preferably 25 to 130g/m²More preferably 30 to 100g/m²More preferably 40 to 80g/m². The gram weight is less than 25g/m²In this case, the strength and rigidity of the filter medium may be insufficient. The gram weight is higher than 130g/m²In this case, the pressure loss may become excessively high.

The thickness of the nonwoven fabric for a support in the filter medium C is preferably 0.2 to 1.4mm, more preferably 0.3 to 1.2mm, and still more preferably 0.4 to 1.0 mm. When the thickness of the nonwoven fabric for a support is less than 0.2mm, the air cleaner is difficult to wrinkle, and when the air cleaner having been wrinkled is used at a high wind speed, the air cleaner may be deformed. On the other hand, if the thickness is more than 1.4mm, the crease processing is difficult, and the height of the raised crease of the crease may not be uniform.

Examples of the adsorbent in the filter medium C include an adsorbent that adsorbs malodorous gas components such as: aldehydes such as formaldehyde and acetaldehyde; amines such as ammonia and trimethylamine; lower fatty acids such as acetic acid and isovaleric acid; mercaptans such as methyl mercaptan; SO (SO)₂、NO₂(ii) a Aromatic hydrocarbons such as toluene and xylene. Examples thereof include iron-based compounds such as activated carbon, natural zeolite, synthetic zeolite, activated alumina, activated clay, sepiolite, and iron oxide, zinc oxide, magnesium oxide, aluminum silicate, silica-zinc oxide composite, silica-alumina-zinc oxide composite, and composite phyllosilicate. Further, a mixture thereof and the like can be mentioned. More preferably, the particles of these adsorbents are modified with a compound that chemisorbs the target gas.

For example, among aldehyde adsorbents in which the target gas is an aldehyde, examples of the compound that can chemisorb the aldehyde that modifies the adsorbent particles include an amino compound, a saturated cyclic secondary amine compound (e.g., morpholine), an azole compound, an aromatic amino acid salt (e.g., o-, m-, p-aminobenzoic acid, o-, m-, p-aminosalicylic acid), imidazole and/or a derivative thereof, an acid hydrazide compound, a polyamine compound, and an aminoguanidine salt compound.

Preferred cumulative volume percent D of adsorbent₅₀1 to 100 μm, more preferably 1 to 100 μm3 to 60 μm, and more preferably 5 to 50 μm. Cumulative volume percent D of adsorbent₅₀When the particle size is less than 1 μm or more than 100 μm, the adsorbent may be dropped more, and the deodorizing performance may be lowered. Also, with the correct cumulative volume fraction D₅₀The adsorbent of (4) can be obtained by classifying the pulverized adsorbent with a sieve, for example. In the present invention, the cumulative volume percentage D is₅₀The particle size means a particle size at which the cumulative value in the particle size distribution of the adsorbent is 50% as measured by a laser diffraction/scattering particle size distribution measuring apparatus (product name MT30002 manufactured by microtrac bel).

The content of the adsorbent of the present invention is preferably 4 to 40g/m in order to obtain a filter medium which is easier to wrinkle²More preferably 5 to 25g/m²More preferably 10 to 15g/m²。

The method for supporting the adsorbent on the nonwoven fabric for support is not particularly limited as long as the adsorbent can be supported on the nonwoven fabric for support as uniformly as possible. An example of the method is a method in which the dispersion is used as a coating liquid, the dispersion is applied to a nonwoven fabric for a support by coating, spraying or the like, and the solvent or dispersion medium is removed by drying or the like to carry the dispersion.

When the adsorbent is supported by the nonwoven fabric for support, a large amount of binder can be used without impairing the adsorbent effect. Examples of the water-soluble binder include polyvinyl alcohol and starch. Examples of the water-dispersible binder include poly (meth) acrylates, polyvinyl acetate, polyvinyl chloride, styrene-acrylic resins, vinyl chloride-acrylic resins, silicone resins, and styrene-butadiene resins. The water-dispersible binder may also be in the form of an emulsion. The adhesive is not limited to these.

The content of the binder is not particularly limited, but is preferably 10 mass% or more based on the mass of the solid content with respect to the adsorbent in order to prevent the falling off of the adsorbent. In order to obtain higher adsorption performance, it is preferably 50% by mass or less.

The charged nonwoven fabric of the filter medium C may be the charged nonwoven fabric of the filter medium a.

< filter material D >

The filter material D is a filter material for an air cleaner as follows: the laminated nonwoven fabric is a laminated nonwoven fabric formed by bonding an electrically charged nonwoven fabric, a protective nonwoven fabric and a support nonwoven fabric, and the protective nonwoven fabric is disposed on the side that comes into contact with the outside air.

The filter material D has a three-layer structure of a protective nonwoven fabric, a charged nonwoven fabric, and a support nonwoven fabric, or a four-layer structure of a protective nonwoven fabric, a charged nonwoven fabric, a protective nonwoven fabric, and a support nonwoven fabric. The "side in contact with the outside air" means a surface (upstream side) of the air filter medium into which air flows or a surface (downstream side) of the air filter medium from which air flows. The filter material D can be repeatedly used by washing with water, that is, is a filter material having excellent resistance to repeated washing with water.

The charged nonwoven fabric of the filter medium D may be the charged nonwoven fabric of the filter medium a.

The protective nonwoven fabric in the filter material D is preferably formed of polyolefin fibers. Among the raw materials constituting the polyolefin-based fibers, the polyolefin-based resin includes homopolymers of propylene, copolymers of propylene and various α -olefins; examples of the polyethylene resin include homopolymers of ethylene and copolymers of ethylene and various α -olefins. From the viewpoint of spinnability and strength characteristics, a polypropylene resin is particularly preferably used. In addition, in order to improve and further strengthen the repeated washing resistance, a water repellent such as a water repellent silicone resin or a fluororesin may be supported on the protective nonwoven fabric. The protective nonwoven fabric in the filter medium D may be provided with the above-described various functions as needed.

The average single fiber diameter of the fibers contained in the protective nonwoven fabric in the filter material D is preferably 5 to 30 μm, more preferably 8 to 20 μm, and still more preferably 10 to 17 μm. If the average single fiber diameter is more than 30 μm, the voids between the fibers of the protective nonwoven fabric become large, and the repeated washing resistance may be poor. On the other hand, if the average filament diameter is less than 5 μm, the voids between the fibers may be narrowed, and the pressure loss may be increased.

Protective nonwoven fabric in filter material DThe gram weight of (A) is preferably 5 to 50g/m²More preferably 8 to 40g/m²More preferably 10 to 20g/m². If the gram weight is more than 50g/m²On the other hand, the grammage is less than 5g/m²The repeated washing resistance may be poor.

The thickness of the protective nonwoven fabric in the filter material D is not particularly limited, but is preferably 0.05 to 1.0mm, more preferably 0.1 to 0.6mm, and further preferably 0.15 to 0.5 mm. When the thickness of the protective nonwoven fabric is less than 0.05mm, the repeated washing resistance may be poor. On the other hand, if the thickness is more than 1.0mm, the crease processing is difficult, and the height of the raised crease of the crease may not be uniform.

The nonwoven fabric for a support of the filter medium D may be the nonwoven fabric for a support of the filter medium C.

The filter medium for an air cleaner of the present invention can be used as a single sheet, but can be used in a valley-like folding process, which is generally called a pleating process, or a corrugating process such as a core in a corrugated cardboard processing, and can also be used as a roll-type filter processed into a roll shape.

[ examples ] A method for producing a compound

The present invention will be described more specifically with reference to the following examples, but the present invention is not limited to these examples. Examples 6 to 10, 15 to 20, 29 to 30, 38 to 40, and 44 to 50 and comparative examples 5 to 10, 15 to 20, 25 to 30, 35 to 40, and 45 to 50 are missing numbers.

Evaluation method

[ method for evaluating pressure loss 1 ]

The resulting filter was cut so that the ventilation size was 300X 300 mm. The cut filter medium is installed in a test wind tunnel capable of introducing air at a constant wind speed so as to prevent leakage from the periphery of the filter medium and to prevent looseness. The pressure difference between the upstream side and the downstream side of the filter medium was measured by a pressure gauge at a wind speed of 0.10m/s, and the pressure loss was measured.

Very high (Execellent): the pressure loss is less than 60 Pa.

Good (Good): the pressure loss is 60Pa or more and less than 70 Pa.

X (Poor): the pressure loss is 70Pa or more.

[ method for evaluating pressure loss 2 ]

The resulting filter was cut so that the ventilation size was 300X 300 mm. The cut filter medium is installed in a test wind tunnel capable of introducing air at a constant wind speed so as to prevent leakage from the periphery of the filter medium and to prevent looseness. The pressure difference between the upstream side and the downstream side of the filter medium was measured by a pressure gauge at a wind speed of 0.5m/s, and the pressure loss was measured. Based on the measured values, the determination is made in the following manner.

O (Execellent): the pressure loss is less than 50 Pa.

Δ (Good): the pressure loss is 50Pa or more and less than 70 Pa.

X (Poor): the pressure loss is 70Pa or more.

[ method for evaluating adhesive Strength ]

The obtained filter medium was subjected to pleating as a post-processing using a reciprocating pleater. The pleated filter medium was checked to confirm whether or not the welded portion was peeled off, and the determination was made as follows.

Good (Good): no peeling, and sufficient adhesive strength.

X (Poor): peeling occurs and the adhesive strength is insufficient.

[ evaluation method of post-processability ]

In the pleating, the filter medium was cut with 41 embossed folds as 1 air cleaner, with the height of the embossed fold of the pleats being 28mm, while the slit-processing was performed with the width of 186 mm. The folded filter medium was held in a rectangular parallelepiped shape of 186X 200X 28mm with uniform convex folds, and in this state, a strip of 30mm wide X250 mm long was attached to the slit end faces of the filter medium so as to completely block the slit end faces, the strip having a thickness of 1mm and 200g/m²The spun-bonded non-woven fabric made of polyester is used for fixing the filter material after the corrugation processing, and the spun-bonded non-woven fabric is coated with a hot-melt adhesive of ethylene vinyl acetate resin with the thickness of about 2 mm. Cutting the excess spun-bonded nonwoven fabric to obtain an air cleaner having an outer shape of 200X 30mmThe rectangular parallelepiped is used as an air cleaner. 100 air cleaners were made. In the air cleaner thus produced, the case where the bonded filter material was warped or rolled up and the case where the height of the embossed fold line of the air cleaner was not uniform were confirmed as "defective", and the defective fraction of the air cleaner was calculated to determine the post-processability in the following manner.

O (Excellent): the defective rate is 1% or less.

Δ (Good): the defective rate is higher than 1% and less than 5%.

X (Poor): the fraction defective exceeded 5%.

[ method for evaluating dust collecting efficiency ]

The resulting filter was cut so that the ventilation size was 300X 300 mm. The cut filter medium is installed in a test wind tunnel capable of introducing air at a constant wind speed so as to prevent leakage from the periphery of the filter medium and to prevent looseness. The number of air dust particles having a particle diameter of 0.3 to 0.5 μm on the upstream side and the downstream side of the filter medium was measured by a particle counter under a wind speed of 0.5m/s, and the dust collection efficiency (%) was calculated from the results of the upstream side and the downstream side measurements. Based on the calculated value, the determination is performed as follows.

O (Execellent): the dust collection efficiency is more than 99.97 percent.

Δ (Good): the dust collection efficiency is more than 99.00% and less than 99.97%.

X (Poor): the dust collection efficiency is lower than 99.00 percent.

[ method for evaluating deodorizing Performance (aldehyde) ]

The obtained filter medium was cut into 100mm × 100mm, and left standing in a 100-liter closed container. Next, after injecting 10ppm of acetaldehyde into the vessel for 30 minutes, the acetaldehyde concentration (ppm) in the vessel was measured by gas chromatography. From the initial concentration of acetaldehyde and the measured value, the gas removal rate (%) was calculated. Based on the calculated value, the determination is performed as follows.

Very high (Execellent): the gas removal rate is 80-100%.

Good (Good): the gas removal rate is more than 50% and less than 80%.

Δ (Average): the gas removal rate is 20% or more and less than 50%.

X (Poor): the gas removal rate is less than 20%.

[ evaluation method of deodorizing ability (Sulfur dioxide) ]

The resulting filter was cut to a ventilation size of 300X 300mm, and test samples were separately prepared. At 1m³The stainless steel box of (1) was equipped with an air cleaner (ACEF 3DS made by Daikin) equipped with the test specimen, and all the filters of the genuine products except the test specimen were removed. After injecting an odor (sulfur dioxide) to reach an initial concentration of about 8.0ppm in the tank, the air cleaner was operated in a turbo mode, and the concentration (ppm) in the tank was measured after 60 minutes. From the initial concentration of odor and the measurement value, the gas removal rate (%) was calculated. Based on the calculated value, the determination is performed as follows.

O (Excellent): the gas removal rate is more than 70%.

Δ (Good): the gas removal rate is 30% or more and less than 70%.

X (Poor): the gas removal rate is lower than 30%.

[ method for evaluating repeated Wash resistance ]

Four sides of the filter material cut in a 300X 300mm format were sealed by heat-sealing with a heat sealer. Subsequently, the substrate was immersed in water for 20 minutes, then allowed to stand in running water for 1 minute, and then dried at 90 ℃ for 1 hour, as 1 cycle. The dust collecting efficiency was measured by the above-described method every cycle, and the test was repeated until the dust collecting efficiency was less than 90%, based on the evaluation criteria described below to determine the result.

O (Excellent): the number of cycles is more than 60.

Δ (Good): the number of cycles is 40 or more and less than 60.

X (Poor): the number of cycles is less than 40.

Example 1

Using a grammage of 70g/m²A spunbonded nonwoven fabric of polyester, and a grammage of 25g/m²The polypropylene-made nonwoven fabric having a collection efficiency of 99.97% or more by a 0.3 to 0.5 μm counting method under a condition of 5.3 cm/sec, which is subjected to permanent charging processing, is laminated by ultrasonic thermal welding to form a laminated nonwoven fabric, and the laminated nonwoven fabric is produced by laminating the laminated nonwoven fabricA filter material formed by non-woven fabrics. In this case, a filter medium in which a pattern forming repetitive pattern is formed as a welded portion and pattern elements constituting the pattern are arranged as follows is obtained.

[ description of the arrangement of the pattern cells in example 1 ]

In ultrasonic heat welding, the following arrangement is adopted: the directions are kept uniform in such a manner that the invisible regular triangles ABC do not overlap each other, and the midpoints of the sides of the regular triangles ABC are made to coincide with the vertices of the adjacent regular triangles (fig. 1). Different rectangular pattern cells are present on 3 lines connecting the centroid G of the regular triangle ABC and each vertex A, B, C, each line is parallel to the long side of each rectangle present thereon, and each pattern cell is formed so that the midpoint of the line present coincides with the centroid of the rectangle (fig. 2). The length of one side of the invisible regular triangle ABC is 22mm, the long side of the rectangle is 2mm, and the short side of the rectangle is 0.5 mm.

Example 2 and comparative example 1

The filters of example 2 and comparative example 1 were obtained, and example 2 was the same as example 1 except that the length of the invisible equilateral triangle ABC side was 20mm, and comparative example 1 was the same as example 1 except that the length of the invisible equilateral triangle ABC side was 25 mm.

Example 3 and comparative example 2

Filter media of example 3 and comparative example 2 were obtained, with example 3 being the same as example 2 except that the size of the pattern cells was 1 mm. times.3 mm, and with comparative example 2 being the same as example 2 except that the size of the pattern cells was 0.5 mm. times.1 mm.

Example 4

A filter medium of example 4 was obtained, and example 4 was the same as example 1 except that the size of the pattern elements was 1.2 mm. times.3.5 mm, and the length of the invisible regular triangle ABC side was 24 mm.

Comparative example 3

A filter medium of comparative example 3 was obtained, and comparative example 3 was the same as example 3 except that the length of the invisible equilateral triangle ABC side was 19 mm.

Comparative example 4

A filter medium of comparative example 4 was obtained, and comparative example 4 was the same as example 4 except that the size of the pattern cells was 1.2 mm. times.4 mm.

Example 5

The filter medium of example 5 was obtained, and in example 5, the minimum angle formed by the flow direction of the filter medium and the line connecting the centers of gravity G of the adjacent invisible right triangles ABC when the filter medium was bonded was 19 °, which was the same as in example 1.

The evaluation results of the filter media of examples 1 to 5 and comparative examples 1 to 4 are shown in Table 1.

[ TABLE 1 ]

As is clear from comparison of the evaluation results of examples 1 to 5 and comparative examples 1 to 4, in the case of the laminated nonwoven fabric comprising 2 or more nonwoven fabrics bonded by welding, the pattern formed by the welded portions forms a repeating pattern, and the average value of the areas of 1 pattern unit constituting the pattern is 1 to 4.2mm²The maximum value of the shortest distance between adjacent pattern units is 10mm or less, and the value obtained by dividing the blockage rate of the welded part by the average value of the areas of 1 pattern unit is 0.8-1.2%/mm²The filter medium of (3) is a filter medium having an excellent balance between pressure loss and adhesive strength and excellent post-processability.

As is clear from comparison between example 2 and comparative example 2, the average value of the areas of 1 pattern cell was less than 1mm²In this case, peeling of the welded portion occurs during the wrinkle processing, and the adhesive strength is poor.

As is clear from comparison of the evaluation results of example 4 and comparative example 4, the average value of the areas of 1 pattern cell was higher than 4.2mm²In this case, the welded portion is large, and the pressure loss increases.

According to the comparison of the evaluation results of example 4 and comparative example 1, the value obtained by dividing the clogging rate by the average value of the areas of 1 pattern unit is less than 0.8%/mm²When the pattern is thinned, the maximum value of the shortest distance between adjacent pattern units is higher than 10mm, and the pattern is post-processedIn addition, the filter material is warped or rolled up, and the reject ratio is high.

As is clear from comparison of the evaluation results of example 3 and comparative example 3, the value obtained by dividing the clogging rate by the average value of the areas of 1 pattern unit was higher than 1.2%/mm²In this case, the pattern becomes dense, and the pressure loss becomes high.

As is clear from comparison of the evaluation results of example 1 and example 5, the inclination of the pattern suppresses the lifting and rolling of the bonded nonwoven fabric, and the post-processability is more preferable.

< filter material A >

[ production of bonded nonwoven fabric: attaching charged nonwoven fabric and protective nonwoven fabric

(ultrasonic bonding nonwoven fabric 1)

Using 15g/m²A spunbonded nonwoven (protective nonwoven) of polypropylene, and for 25g/m²The polypropylene melt-blown nonwoven fabric of (1) is subjected to a permanent electrification treatment, and a nonwoven fabric (charged nonwoven fabric) having a collection efficiency of 99.97% or more by a 0.3 to 0.5 μm counting method under a condition of 5.3 cm/sec is bonded by ultrasonic welding to produce an ultrasonic bonded nonwoven fabric (1).

In the ultrasonic bonding process, invisible regular triangles ABC are arranged in a uniform direction so as not to overlap each other, and the centers of the sides of the regular triangles ABC are arranged so as to coincide with the vertices of adjacent regular triangles (fig. 1), rectangular pattern elements are present on a line connecting the center of gravity G and each vertex A, B, C of the regular triangles ABC, and the pattern elements are arranged so that the line is parallel to the long sides of the rectangle and the center of gravity of the rectangle coincides with the center of gravity of the rectangle (fig. 2). The length of one side of the invisible regular triangle ABC is 22mm, the long side of the rectangle is 2mm, and the short side of the rectangle is 0.5 mm.

(ultrasonic bonding nonwoven fabric 2)

The obtained ultrasonic bonded nonwoven fabric 2 was the same as the ultrasonic bonded nonwoven fabric 1 except that the length of the invisible regular triangle ABC side was 20 mm.

(ultrasonic bonding nonwoven fabric 3)

The obtained ultrasonic bonded nonwoven fabric 3 was the same as the ultrasonic bonded nonwoven fabric 1 except that the length of the invisible regular triangle ABC side was 25 mm.

(ultrasonic bonding nonwoven fabric 4)

The obtained ultrasonic bonded nonwoven fabric 4 was the same as the ultrasonic bonded nonwoven fabric 2 except that the size of the pattern cells was 1mm × 3 mm.

(ultrasonic bonding nonwoven fabric 5)

The obtained ultrasonic bonded nonwoven fabric 5 was the same as the ultrasonic bonded nonwoven fabric 2 except that the size of the pattern cells was 0.5mm × 1 mm.

(ultrasonic bonding nonwoven fabric 6)

The obtained ultrasonic bonded nonwoven fabric 6 was the same as the ultrasonic bonded nonwoven fabric 1 except that the size of the pattern cells was 1.2mm × 3.5mm and the length of the invisible regular triangle ABC side was 24 mm.

(ultrasonic bonding nonwoven fabric 7)

The obtained ultrasonic bonded nonwoven fabric 7 was the same as the ultrasonic bonded nonwoven fabric 4 except that the length of the invisible equilateral triangle ABC side was 19 mm.

(ultrasonic bonding nonwoven fabric 8)

The obtained ultrasonic bonded nonwoven fabric 8 was the same as the ultrasonic bonded nonwoven fabric 6 except that the size of the pattern cells was 1.2mm × 4 mm.

Example 11

Nonwoven fabric for support (60 g/m)²Spun-bonded nonwoven fabric made of polyester) was sprayed with 300g/m of a mixed powder prepared by mixing 50 parts by mass of a thermoplastic binder (ethylene-vinyl acetate copolymer powder having a softening point of 100 ℃) with 100 parts by mass of an aldehyde adsorbent (4-amino-1, 2, 4-triazole and iron chloride-impregnated granular activated carbon)²Heating the support nonwoven fabric from the spraying side by an infrared heater having a surface temperature of 150 ℃, stopping the heating after the thermoplastic adhesive is plasticized, rapidly superposing the adsorbent spraying side of the support nonwoven fabric on the charged nonwoven fabric side of the ultrasonic bonding nonwoven fabric 1, sandwiching the laminate between 2 rolls, pressing the laminate, and integrating the laminate by bonding to obtain a solidThe filter of example 11.

Example 12

The same method as in example 11 was repeated except that the ultrasonic bonded nonwoven fabric 1 used in example 11 was replaced with the ultrasonic bonded nonwoven fabric 2, to obtain a filter medium of example 12.

Example 13

The filter medium of example 13 was obtained in the same manner as in example 11 except that the ultrasonic bonded nonwoven fabric 1 used in example 11 was replaced with the ultrasonic bonded nonwoven fabric 4.

Example 14

The filter medium of example 14 was obtained in the same manner as in example 11 except that the ultrasonic bonded nonwoven fabric 6 was used instead of the ultrasonic bonded nonwoven fabric 1 used in example 11.

Comparative example 11

A filter medium of comparative example 11 was obtained in the same manner as in example 11 except that the ultrasonic bonded nonwoven fabric 1 used in example 11 was replaced with the ultrasonic bonded nonwoven fabric 3.

Comparative example 12

A filter medium of comparative example 12 was obtained in the same manner as in example 11 except that the ultrasonic bonded nonwoven fabric 1 used in example 11 was replaced with the ultrasonic bonded nonwoven fabric 5.

Comparative example 13

A filter medium of comparative example 13 was obtained in the same manner as in example 11 except that the ultrasonic bonded nonwoven fabric 1 used in example 11 was replaced with the ultrasonic bonded nonwoven fabric 7.

Comparative example 14

A filter medium of comparative example 14 was obtained in the same manner as in example 11 except that the ultrasonic bonded nonwoven fabric 8 was used in place of the ultrasonic bonded nonwoven fabric 1 used in example 11.

The evaluation results of examples 11 to 14 and comparative examples 11 to 14 are shown in Table 2.

[ TABLE 2 ]

As is clear from comparison of the evaluation results of examples 11 to 14 and comparative examples 11 to 14, in the case of the laminated nonwoven fabric comprising 2 or more nonwoven fabrics bonded by welding, the pattern formed by the welded portions forms a repeating pattern, and the average value of the areas of 1 pattern unit constituting the pattern is 1 to 4.2mm²The maximum value of the shortest distance between adjacent pattern units is 10mm or less, and the value obtained by dividing the blockage rate of the welded part by the average value of the areas of 1 pattern unit is 0.8-1.2%/mm²The filter medium of (2) is excellent in the balance between pressure loss and adhesive strength, and is excellent in dust collection efficiency and deodorizing performance and low in defective rate.

As is clear from comparison between example 12 and comparative example 12, the average value of the areas of 1 pattern cell was less than 1mm²In the case of the wrinkle processing, the welded portion is peeled off, and the adhesive strength is poor.

As is clear from comparison of the evaluation results of example 14 and comparative example 14, the average value of the areas of 1 pattern cell was higher than 4.2mm²In this case, the welded portion is large, and the pressure loss increases.

As is clear from comparison of the evaluation results of example 14 and comparative example 11, the average value of the area obtained by dividing the clogging rate by 1 pattern unit was less than 0.8%/mm²In the case of the pattern formation, the patterns become sparse, the maximum value of the shortest distance between adjacent pattern units is higher than 10mm, and the filter material is warped and rolled up during the post-processing, resulting in a high defective rate.

As is clear from comparison of the evaluation results of example 13 and comparative example 13, the value obtained by dividing the clogging rate by the average value of the areas of 1 pattern unit was more than 1.2%/mm²In this case, the pattern becomes dense, and the pressure loss becomes high.

< filter material B >

Example 21

Using a nonwoven fabric for a support (having a grammage of 50 g/m)²A chemically bonded nonwoven fabric composed of polyester fibers and acrylic resin), and 30g/m for the grammage²The melt-blown nonwoven fabric of polypropylene is permanently charged and processed at 5.3 cm/secThe charged nonwoven fabric having a collection efficiency of 99.97% or more by the 0.3 to 0.5 μm counter method under the conditions was bonded by ultrasonic welding (ultrasonic bonding) to obtain a laminated nonwoven fabric, and the air filter material of example 21 was obtained.

In ultrasonic bonding processing, invisible regular triangles ABC are arranged in a uniform direction so as not to overlap each other, and the centers of the sides of the regular triangles ABC are arranged so as to coincide with the vertices of adjacent regular triangles (fig. 1), rectangular pattern elements are present on a line connecting the center of gravity G of the regular triangle ABC and the vertices A, B, C, and the pattern elements are arranged so that the line is parallel to the long sides of the rectangle and the centers of the lines coincide with the center of gravity of the rectangle (fig. 2). The length of one side of the invisible regular triangle ABC is 22mm, the long side of the rectangle is 2mm, and the short side of the rectangle is 0.5 mm.

Example 22

The obtained filter medium of example 22 was the same as that of example 21 except that the length of the invisible equilateral triangle ABC side was 20 mm.

Comparative example 21

The air cleaner filter material of comparative example 21 was obtained in the same manner as example 21, except that the length of the non-visible regular triangle ABC side was 25 mm.

Comparative example 22

The obtained filter medium of comparative example 22 was not the same as example 22 except that the size of the pattern cells was 0.5mm × 1 mm.

Example 23

The obtained filter medium of example 23 was the same as that of example 21 except that the size of the pattern elements was 1.2 mm. times.3.5 mm, and the length of the invisible equilateral triangle ABC side was 24 mm.

Comparative example 23

The resulting filter medium of comparative example 23 was the same as that of example 21, except that the size of the pattern cells was 1mm × 3mm, and the length of the invisible equilateral triangle ABC side was 19 mm.

Comparative example 24

The resulting filter medium of comparative example 24 was the same as example 23 except that the size of the pattern cells was 1.2 mm. times.4 mm.

Example 24

The obtained filter medium of example 24 was a nonwoven fabric for support made of a material having a grammage of 20g/m²The nonwoven fabric chemically bonded with the polyester fibers and the acrylic resin in (1) was the same as in example 21 except for the above.

Example 25

The obtained filter medium of example 25 was a nonwoven fabric for support made of a material having a grammage of 120g/m²The same as in example 21 was repeated except that the chemically bonded nonwoven fabric composed of the polyester fibers and the acrylic resin was used.

Example 26

The obtained filter medium of example 26 was a nonwoven fabric for supporting the filter medium, which had a grammage of 50g/m²The same as in example 21 was repeated except that the heat-bondable nonwoven fabric composed of the polyester fibers and the polyester binder fibers was used.

Example 27

The charged nonwoven fabric of the filter medium of example 27 was 5g/m in terms of grammage²The same as in example 21 was conducted except that the polypropylene melt-blown nonwoven fabric was subjected to permanent charging processing, and the charged nonwoven fabric had a collection efficiency of 99.97% or more by 0.3 to 0.5 μm counting method under a condition of 5.3 cm/sec.

Example 28

The charged nonwoven fabric of the filter medium of example 28 was 60g/m in terms of grammage²The same as in example 21 was conducted except that the polypropylene melt-blown nonwoven fabric was subjected to permanent charging processing, and the charged nonwoven fabric had a collection efficiency of 99.97% or more by the 0.3 to 0.5 μm counter method under the condition of 5.3 cm/sec.

The evaluation results of examples 21 to 28 and comparative examples 21 to 24 are shown in tables 3 and 4.

[ TABLE 3 ]

[ TABLE 4 ]

As is clear from comparison of the evaluation results of examples 21 to 28 and comparative examples 21 to 24, the pattern formed by the weld portion of the laminated nonwoven fabric including 2 or more nonwoven fabrics welded and bonded forms a repeating pattern, and the average value of the area of 1 pattern unit constituting the pattern is 1 to 4.2mm²The maximum value of the shortest distance between adjacent pattern units is 10mm or less, and the value obtained by dividing the blockage rate of the welded part by the average value of the areas of 1 pattern unit is 0.8-1.2%/mm²The filter medium of (2) is excellent in the balance between pressure loss and adhesive strength, and is excellent in dust collection efficiency and low in defective rate.

As is clear from comparison of the evaluation results of example 21 and comparative example 21, the average value of the area obtained by dividing the clogging rate by 1 pattern unit was less than 0.8%/mm²In the case where the patterns are sparse, the maximum value of the shortest distance between adjacent pattern units is higher than 10mm, and the filter material is warped or curled up during the post-processing, resulting in a high defective rate.

As is clear from comparison between example 22 and comparative example 22, the average value of the areas of 1 pattern cell was less than 1mm²In this case, peeling of the welded portion occurs during the wrinkle processing, and the adhesive strength is poor.

As is clear from comparison of the evaluation results of example 22 and comparative example 23, the average value of the area obtained by dividing the clogging rate by 1 pattern unit was less than 1.2%/mm²In this case, the pattern becomes dense, and the pressure loss becomes high.

As is clear from comparison of the evaluation results of example 23 and comparative example 24, the average value of the areas of 1 pattern cell was higher than 4.2mm²In this case, the welded portion is large, and the pressure loss increases.

Example 31

The support nonwoven fabric comprises polyester fiber and acrylic resin and has a grammage of 50g/m²The nonwoven fabric for a support is impregnated with an aldehyde adsorbent (aluminum silicate modified with an amino compound, having an average particle diameter of 5 μm) so as to be impregnated with the nonwoven fabricThe content of it is 10g/m²Styrene acrylic resin emulsion adhesive, to a content of 4g/m²Then, the resultant was dried at 120 ℃ to prepare a nonwoven fabric for a support carrying an aldehyde adsorbent. Then, the nonwoven fabric for a support was used, and the nonwoven fabric for a support was used for a nonwoven fabric for a support of 30g/m²The melt-blown nonwoven fabric made of polypropylene was subjected to permanent electrification processing, and an electrified nonwoven fabric having a collection efficiency of 99.97% or more by a 0.3 to 0.5 μm counting method under a condition of 5.3 cm/sec was subjected to ultrasonic welding and bonded to obtain the filter medium of example 31.

When bonding processing is performed by ultrasonic welding, invisible regular triangles ABC are arranged in a uniform direction so as not to overlap each other, and the centers of the sides of the regular triangles ABC are arranged so as to coincide with the vertices of adjacent regular triangles (fig. 1), rectangular pattern elements are present on a line connecting the center of gravity G and the vertices A, B, C of the regular triangles ABC, and the pattern elements are arranged so that the line is parallel to the long sides of the rectangle, and the center of the line coincides with the center of gravity of the rectangle (fig. 2). The length of one side of the invisible regular triangle ABC is 22mm, the long side of the rectangle is 2mm, and the short side of the rectangle is 0.5 mm.

Example 32

The obtained filter medium of example 32 was the same as that of example 31 except that the length of the invisible equilateral triangle ABC side was 20 mm.

Comparative example 31

The obtained filter medium of comparative example 31 was not the same as that of example 31 except that the length of the invisible equilateral triangle ABC side was 25 mm.

Comparative example 32

The resulting filter medium of comparative example 32 was the same as example 32 except that the size of the pattern cells was 0.5mm × 1 mm.

Example 33

The obtained filter medium of example 33 was the same as that of example 31 except that the size of the pattern elements was 1.2 mm. times.3.5 mm, and the length of the invisible equilateral triangle ABC side was 24 mm.

Comparative example 33

The resulting filter medium of comparative example 33 was the same as that of example 31 except that the size of the pattern cells was 1mm × 3mm, and the length of the invisible regular triangle ABC side was 19 mm.

Comparative example 34

The filter medium of comparative example 34 was the same as that of example 33 except that the size of the pattern cells was 1.2 mm. times.4 mm.

Example 34

The obtained filter medium of example 34 was a nonwoven fabric for support, which was composed of polyester fibers and acrylic resin and had a grammage of 25g/m²The same as in example 31 except that the chemically bonded nonwoven fabric of (3) was used.

Example 35

The obtained filter medium of example 35, in which the nonwoven fabric for supporting the substrate was 130g/m composed of polyester fibers and acrylic resin²The same as in example 31 except that the chemically bonded nonwoven fabric of (3) was used.

Example 36

The same procedure as in example 31 was repeated except that the average particle size of the aldehyde adsorbent in the obtained filter medium of example 36 was 1 μm.

Example 37

The same procedure as in example 31 was repeated except that the average particle size of the aldehyde adsorbent in the obtained filter medium of example 37 was 50 μm.

The evaluation results of examples 31 to 37 and comparative examples 31 to 34 are shown in tables 5 and 6.

[ TABLE 5 ]

[ TABLE 6 ]

As is clear from comparison of the evaluation results of examples 31 to 37 and comparative examples 31 to 34, the pattern formed by the welded portion was formed in the laminated nonwoven fabric comprising 2 or more layers of nonwoven fabric bonded by weldingA repeating pattern having an average value of the area of 1 pattern unit constituting the pattern of 1 to 4.2mm²The maximum value of the shortest distance between adjacent pattern units is 10mm or less, and the value obtained by dividing the blockage rate of the welded part by the average value of the areas of 1 pattern unit is 0.8-1.2%/mm²The filter medium of (2) is excellent in the balance between pressure loss and adhesive strength, and is excellent in dust collection efficiency and deodorizing performance and low in defective rate.

As is clear from comparison between example 32 and comparative example 32, the average value of the areas of 1 pattern cell was less than 1mm²In the case of the post-processing, the welded portion is peeled off, and the adhesive strength is poor.

As is clear from comparison of the evaluation results of example 33 and comparative example 34, the average value of the areas of 1 pattern cell was higher than 4.2mm²In this case, the welded portion is large, and the pressure loss increases.

As is clear from comparison of the evaluation results of example 33 and comparative example 31, the average value of the area obtained by dividing the clogging rate by 1 pattern unit was less than 0.8%/mm²In the case where the patterns are sparse, the maximum value of the shortest distance between adjacent pattern units is higher than 10mm, and the filter material is warped and curled up during post-processing, resulting in a high defective rate.

From a comparison of the evaluation results of example 32 and comparative example 33, the value obtained by dividing the clogging rate by the average value of the areas of 1 pattern unit was less than 1.2%/mm²In this case, the pattern becomes dense, and the pressure loss becomes high.

EXAMPLE 41

The support nonwoven fabric comprises polyester fiber and acrylic resin and has a grammage of 50g/m²The chemically bonded nonwoven fabric for a support, which is impregnated with the coating composition in an amount of 12g/m²Powdered activated carbon (adsorbent, coconut shell activated carbon, cumulative volume percent D)₅₀30 μm), and a content of 4g/m²The styrene acrylic resin emulsion binder of (2) was dried at 120 ℃ to prepare an adsorbent-supporting nonwoven fabric for a support.

Then, a nonwoven fabric for a support was used, and the amount of the nonwoven fabric for a support was adjusted to 30g/m²The polypropylene melt-blown nonwoven fabric is permanently treatedThe charged nonwoven fabric having a collection efficiency of 99.97% or more by 0.3 to 0.5 μm counting method under a condition of 5.3 cm/sec was subjected to charging processing, and was bonded by ultrasonic welding to obtain the filter medium of example 41.

When bonding processing is performed by ultrasonic welding, invisible regular triangles ABC are arranged in a uniform direction so as not to overlap each other, and the centers of the sides of the regular triangles ABC are arranged so as to coincide with the vertices of adjacent regular triangles (fig. 1), rectangular pattern elements are present on a line connecting the center of gravity G of the regular triangle ABC and the vertices A, B, C, and the pattern elements are arranged so that the line is parallel to the long sides of the rectangle and the centers of the lines coincide with the center of gravity of the rectangle (fig. 2). The length of one side of the invisible regular triangle ABC is 22mm, the long side of the rectangle is 2mm, and the short side of the rectangle is 0.5 mm.

Example 42

The obtained filter medium of example 42 was the same as that of example 41 except that the length of the invisible equilateral triangle ABC side was 20 mm.

Comparative example 41

The obtained filter medium of comparative example 41 was the same as that of example 41 except that the length of the invisible equilateral triangle ABC side was 25 mm.

Comparative example 42

The resulting filter medium of comparative example 42 was the same as example 42 except that the size of the pattern cells was 0.5mm × 1 mm.

Example 43

The resulting filter medium of example 43 was the same as that of example 41 except that the size of the pattern elements was 1.2 mm. times.3.5 mm, and the length of the invisible equilateral triangle ABC side was 24 mm.

Comparative example 43

The resulting filter medium of comparative example 43 was the same as that of example 41 except that the size of the pattern cells was 1mm × 3mm, and the length of the invisible equilateral triangle ABC side was 19 mm.

Comparative example 44

The resulting filter medium of comparative example 44 was the same as example 43 except that the size of the pattern cells was 1.2 mm. times.4 mm.

The evaluation results of examples 41 to 43 and comparative examples 41 to 44 are shown in Table 7.

[ TABLE 7 ]

As is clear from comparison of the evaluation results of examples 41 to 43 and comparative examples 41 to 44, the pattern formed by the welded portion of the laminated nonwoven fabric comprising 2 or more nonwoven fabrics is formed into a repeating pattern, and the average value of the area of 1 pattern unit forming the pattern is 1 to 4.2mm²The maximum value of the shortest distance between adjacent pattern units is 10mm or less, and the value obtained by dividing the blockage rate of the welded part by the average value of the areas of 1 pattern unit is 0.8-1.2%/mm²The filter medium of (2) is excellent in the balance between pressure loss and adhesive strength, and is excellent in dust collecting performance and deodorizing performance and low in defective rate.

As is clear from comparison between example 42 and comparative example 42, the average value of the areas of 1 pattern cell was less than 1mm²In the case of the wrinkle processing, the welded portion is peeled off, and the adhesive strength is poor.

As is clear from comparison of the evaluation results of example 43 and comparative example 44, the average value of the areas of 1 pattern cell was less than 4.2mm²In this case, the welded portion is large, and the pressure loss increases.

As is clear from comparison of the evaluation results of example 43 and comparative example 41, the average value of the area obtained by dividing the clogging rate by 1 pattern unit was less than 0.8%/mm²In the case where the patterns are sparse, the maximum value of the shortest distance between adjacent pattern units is more than 10mm, the filter material is warped or curled, the defective fraction is high, and the post-processability is poor.

As is clear from comparison of the evaluation results of example 42 and comparative example 43, the value obtained by dividing the clogging rate by the average value of the areas of 1 pattern unit was more than 1.2%/mm²In this case, the pattern becomes dense, and the pressure loss becomes high.

< filter material D >

Example 51

As the charged nonwoven fabric, 30g/m²The polypropylene melt-blown nonwoven fabric is subjected to permanent electrification processing, and has a dust collection efficiency of 99.97% or more by a 0.3 to 0.5 μm counter method under a condition of 5.3 cm/sec.

As the protective nonwoven fabric, 15g/m was used²The polypropylene of (2) is a spunbonded nonwoven.

The nonwoven fabric for the support is composed of polyester fiber and acrylic resin and has a grammage of 50g/m²The chemically bonded nonwoven fabric of (1).

The laminate was laminated in a three-layer structure of a protective nonwoven fabric, a charged nonwoven fabric and a support nonwoven fabric, and then bonded by ultrasonic welding to obtain a filter medium of example 51.

In the bonding process by ultrasonic welding, invisible regular triangles ABC are arranged in a uniform direction so as not to overlap each other and so that the midpoints of the sides of the regular triangles ABC coincide with the vertices of adjacent regular triangles (fig. 1), rectangular pattern elements are present on a line connecting the center of gravity G of the regular triangle ABC and the vertices A, B, C, and the pattern elements are arranged so that the line is parallel to the long sides of the rectangle and the midpoints of the lines coincide with the center of gravity of the rectangle (fig. 2). The length of one side of the invisible regular triangle ABC is 22mm, the long side of the rectangle is 2mm, and the short side of the rectangle is 0.5 mm.

Example 52

The obtained filter medium of example 52 was the same as that of example 51 except that the length of the invisible equilateral triangle ABC side was 20 mm.

Comparative example 51

The obtained filter medium of comparative example 51 was the same as example 51 except that the length of the invisible equilateral triangle ABC side was 25 mm.

Comparative example 52

The filter medium of comparative example 52 was the same as example 52 except that the size of the pattern cells was 0.5mm × 1 mm.

Example 53

The obtained filter medium of example 53 was the same as that of example 51 except that the size of the pattern elements was 1.2 mm. times.3.5 mm, and the length of the invisible equilateral triangle ABC side was 24 mm.

Comparative example 53

The resulting filter medium of comparative example 53 was the same as that of example 51, except that the size of the pattern cells was 1mm × 3mm, and the length of the invisible equilateral triangle ABC side was 19 mm.

Comparative example 54

The resulting filter medium of comparative example 54 was the same as example 53 except that the size of the pattern cells was 1.2 mm. times.4 mm.

The evaluation results of examples 51 to 53 and comparative examples 51 to 54 are shown in Table 8.

[ TABLE 8 ]

As is clear from comparison of the evaluation results of examples 51 to 53 and comparative examples 51 to 54, the pattern formed by the weld portion of the laminated nonwoven fabric comprising 2 or more nonwoven fabrics joined by welding forms a repeating pattern, and the average value of the areas of 1 pattern unit constituting the pattern is 1 to 4.2mm²The maximum value of the shortest distance between adjacent pattern units is 10mm or less, and the value obtained by dividing the blockage rate of the welded part by the average value of the areas of 1 pattern unit is 0.8-1.2%/mm²The filter medium for an air cleaner of (1) is a filter medium which has a low pressure loss, has sufficient adhesive strength at a welded portion, can suppress the occurrence of lifting and turning, has excellent dust collecting performance, is less likely to deteriorate in dust collecting performance after repeated washing, and has excellent post-processability.

As is clear from comparison between example 52 and comparative example 52, the average value of the areas of 1 pattern cell was less than 1mm²In this case, the welded portion is peeled off, resulting in poor adhesion strength.

As is clear from comparison of the evaluation results of example 53 and comparative example 54, the average value of the areas of 1 pattern cell was higher than 4.2mm²In this case, the welded portion is large, and the pressure loss increases。

As is clear from comparison of the evaluation results of example 53 and comparative example 51, the average value of the area obtained by dividing the clogging rate by 1 pattern unit was less than 0.8%/mm²In the case where the patterns are sparse, the maximum value of the shortest distance between adjacent pattern units is more than 10mm, the filter material is warped or curled, the defective fraction is high, and the post-processability is poor.

As is clear from comparison of the evaluation results of example 52 and comparative example 53, the average value of the area obtained by dividing the clogging rate by 1 pattern unit was less than 1.2%/mm²In this case, the pattern becomes dense, and the pressure loss becomes high.

[ Industrial Applicability ]

The present invention can be used as a filter medium for an air cleaner used in an air conditioner or the like.

Claims

1. A filter medium for an air cleaner, comprising a laminated nonwoven fabric formed by laminating 2 or more layers of nonwoven fabrics, wherein the lamination is performed by fusion bonding, a plurality of pattern units formed by the shape of the fusion bonded part form a group to form a pattern exhibiting a repeating pattern, and the area of 1 pattern unit is 1 to 4.2mm on average²The shortest distance between adjacent pattern units is 10mm or less, and the blocking rate of the welded part in percentage divided by the average value of the areas of 1 pattern unit is 0.8-1.2%/mm²The blocking ratio of the welded portion corresponds to a ratio of a total area of the pattern cells included in the repetitive pattern among the areas of the repetitive pattern formed by the pattern cells.

2. The filter medium for an air cleaner according to claim 1, wherein the repeating pattern of the pattern elements is formed by: in an invisible repeating pattern in which invisible triangles ABC having one side of 20-24 mm are arranged so that the direction is uniform and does not overlap each other so that the midpoint of each side of the regular triangle ABC coincides with each vertex of a triangle ABC adjacent to each side, rectangular pattern elements having a long side of 2-3 mm and a short side of 0.5-1 mm are present on a straight line connecting the center of gravity G of the regular triangle ABC and each vertex A, B, C, such that the straight line is parallel to the long side of the rectangle and the midpoint of the straight line coincides with the center of gravity of the rectangle.

3. The filter medium for an air cleaner according to claim 2, wherein a straight line connecting the centers of gravity G of the adjacent 2 regular triangles ABC forms a minimum angle of 5 to 25 ° with respect to a flow direction of the filter medium processing.

4. The filter medium for an air cleaner according to any one of claims 1 to 3, wherein the laminated nonwoven fabric is a bonded nonwoven fabric obtained by bonding a charged nonwoven fabric and a protective nonwoven fabric, and an adsorbent is sealed between the support nonwoven fabric and the bonded nonwoven fabric by a thermoplastic adhesive.

5. The filter medium for an air cleaner according to any one of claims 1 to 3, wherein the laminated nonwoven fabric is a laminated nonwoven fabric in which a support nonwoven fabric and a charged nonwoven fabric are bonded together.

6. The filter medium for an air cleaner according to claim 5, wherein the adsorbent is carried by a nonwoven fabric for a support.

7. The filter medium for an air cleaner according to any one of claims 1 to 3, wherein the laminated nonwoven fabric is a laminated nonwoven fabric in which a charged nonwoven fabric, a protective nonwoven fabric and a support nonwoven fabric are bonded together, and the protective nonwoven fabric is disposed on a side in contact with an external air.