JP7788906B2 - Deodorizing fiber structure, air filter media and air filter - Google Patents

Description

The present invention relates to a fiber structure, an air filter medium, and an air filter having deodorizing properties.

In recent years, due to the health impacts of dust (yellow sand), PM2.5, and pollen from cedar and cypress trees from the deserts and arid regions of inland East Asia, as well as the spread of viral infections such as influenza, many living environments have seen the use of air purifiers and air conditioners to purify, regulate temperature, and control humidity indoors, instead of opening windows to ventilate the air. In particular, there is strong market demand for features to improve comfort in indoor spaces such as homes, workplaces, and automobiles, and as air purification devices become more widespread, there is also a demand for various high-performance air filter media used in air purification devices.

The odorous gas components present in living environments such as homes, workplaces, and automobiles include 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; _SO2 , _NO2 ; and aromatic hydrocarbons such as toluene and xylene. Among these are those classified as 22 types of specific odorous substances specified in the Offensive Odor Prevention Act, as well as 13 types of volatile organic compounds (VOCs) for which the Ministry of Health, Labour and Welfare has set concentration guideline values.

Against this background, there is a growing need for air filter media with deodorizing properties that can quickly reduce the concentration of odorous gas components indoors, protect the health of people and pets, and make indoor spaces more comfortable.

For example, in order to provide a fiber sheet suitable for an air filter medium that selectively and efficiently removes only aldehydes without using activated carbon or impregnated activated carbon, a fiber sheet characterized by carrying specific inorganic particles and an acid hydrazide on at least the surface of the fiber has been proposed (see Patent Document 1). This proposal specifies a fiber sheet in which at least one type of inorganic particle is zeolite, and the zeolite has a SiO ₂ /Al ₂ O ₃ molar ratio of 20 to 300. This fiber sheet has good aldehyde removal ability, but when carrying zeolite on the fiber sheet by impregnation coating or the like, it can be difficult to handle compared to other inorganic particles, and compared to silicon dioxide, alumina, and titanium dioxide, the material cost is generally high, making it less desirable from an economical standpoint.

Furthermore, with the objective of providing a deodorizing fiber structure that efficiently removes aldehydes and has an extremely low risk of secondary odor generation, the following are provided: (1) a deodorizing fiber structure comprising a fiber structure carrying inorganic particles and a water-soluble amine compound, the fiber structure having an equilibrium moisture regain of 15% by mass or less in an environment adjusted to a temperature of 25°C and a relative humidity of 75%, and a pH of 3.5 to 7 when immersed in water to a concentration of 3% by mass; (2) the deodorizing fiber structure according to (1), in which the inorganic particles have an equilibrium moisture regain of 10% by mass or less in an environment adjusted to a temperature of 25°C and a relative humidity of 75%; (3) the deodorizing fiber structure according to (1) or (2), in which the inorganic particles are hydrophobic porous particles; and (4) the deodorizing fiber structure according to (3), in which the hydrophobic porous particles have an average pore diameter of 2 to 50 nm. (5) The deodorizing fiber structure according to any one of (1) to (4), wherein the inorganic particles and the water-soluble amine compound form pores on the surface of the fibers, the volume of pores having a pore diameter of 20 nm or less occupying 40% or less of the total pore volume, and the specific surface area is 1 to 30 m ² /g. (6) The deodorizing fiber structure according to any one of (1) to (5), wherein the inorganic particles have a number average particle size of 1 μm or less and a specific surface area measured by the BET method of 15 to 250 m ² /g. (7) The deodorizing fiber structure according to any one of (1) to (6), wherein the inorganic particles contain at least one kind selected from the group consisting of silicon dioxide, alumina, and titanium dioxide. (8) The deodorizing fiber structure according to any one of (1) to (7), wherein the water-soluble amine compound contains an acid hydrazide compound. (9) The deodorizing fiber structure according to any one of (1) to (8), which contains a poorly water-soluble pH adjuster. (10) The deodorizing fiber structure according to (9), wherein the poorly water-soluble pH adjuster is a flame retardant. (11) The deodorizing fiber structure according to any one of (1) to (10), wherein the inorganic particles and the water-soluble amine compound are supported on the fiber surface by a binder. (12) The deodorizing fiber structure according to (1) to (10), wherein the inorganic particles have a number-average particle size of 50 to 2000 μm, and the water-soluble amine compound is attached to the inorganic particles and sandwiched between the fibers. (13) An air filter has been proposed that is constructed using the deodorizing fiber structure according to any one of (1) to (12) (see Patent Document 2). However, if the number average particle size of the inorganic particles is 1 μm or less, the inorganic particles will be distributed evenly over the fiber sheet, filling the voids in the fiber structure, which may increase the pressure loss of the air filter, make it difficult to obtain a sufficient dust retention capacity, or cause difficulties in handling the inorganic particles, such as causing a lot of dust flying when producing a fiber structure carrying the inorganic particles, which is undesirable. Note that the dust retention capacity is measured according to a method in accordance with JIS D1612, in which a test powder is introduced at a test air speed of 2.7 m/sec, the test is terminated when the pressure loss reaches 200 Pa, and the dust retention capacity at that stage is measured; the higher the value, the higher the dust collection ability.

In order to provide a filter medium with excellent VOC adsorption performance, a filter medium has been proposed that includes a nonwoven fabric carrying an adsorbent, which is a particle having an average particle diameter of 1 μm or less, supported by a binder, in which the weight ratio of the adsorbent to the binder is within the range of 93%:7% to 99.5%:0.5% by mass (see Patent Document 3). Air filter medium in which an adsorbent is supported on a fiber sheet for deodorizing specific gases is widely known, but when the adsorbent is a particle having an average particle diameter of 1 μm or less, the adsorbent particles are also distributed evenly across the nonwoven fabric, filling the voids in the nonwoven fabric and increasing the pressure loss of the filter medium, preventing sufficient dust retention, and causing difficulties in handling the adsorbent, such as the generation of a lot of dust when manufacturing the nonwoven fabric carrying the adsorbent particles.

Japanese Patent Application Laid-Open No. 2007-167632 Patent No. 5428857 JP 2015-157250 A

The objective of the present invention is to provide a deodorizing fiber structure that uses inorganic particles that efficiently deodorize malodorous gas components, particularly aldehydes such as acetaldehyde, and that are easy to handle and economical when supporting the inorganic particles on the fiber structure, as well as an air filter medium and air filter that use the same.

The object of the present invention can be achieved by the following means.
(1) A deodorizing fiber structure comprising inorganic particles and a water-soluble amine compound supported on a fiber structure, wherein the inorganic particles are porous particles and are one or more types of inorganic particles selected from the group consisting of silicon dioxide, alumina, and titanium dioxide, the inorganic particles have an average particle size of 1 to 50 μm, a specific surface area of 100 m ² /g or more, a pore volume of 0.3 ml/g or more, and a pH of a 10% by mass dispersion of the inorganic particles in water is 6.6 or more.
(2) An air filter medium using the deodorizing fiber structure described in (1) above. (3) An air filter using the deodorizing fiber structure described in (1) above.

The present invention provides a deodorizing fiber structure that has excellent deodorizing performance for aldehydes such as acetaldehyde and allows for easy handling of inorganic particles when supporting the inorganic particles on the fiber structure, as well as an air filter medium and air filter that use the same.

The deodorizing fiber structure, air filter medium, and air filter of the present invention are described in detail below.

The deodorizing fiber structure of the present invention is a deodorizing fiber structure in which inorganic particles and a water-soluble amine compound are supported on a fiber structure, and the air filter medium is a filter medium used in an air filter, and is a filter medium that uses the deodorizing fiber structure of the present invention.

The inorganic particles used in the present invention are porous particles and are one or more types of inorganic particles selected from the group consisting of silicon dioxide, alumina, and titanium dioxide. Of these, silicon dioxide is preferred.

From the perspective of deodorizing performance and ease of handling, the average particle size of the inorganic particles is 1 to 50 μm, more preferably 2 to 40 μm, and even more preferably 3 to 30 μm. If the average particle size is less than 1 μm, the voids between the fibers of the fiber structure will be filled with small particles, resulting in high pressure loss and insufficient dust retention. Furthermore, handling of the inorganic particles will be difficult, as more dust will fly around. If the average particle size is greater than 50 μm, the adhesion area between the fibers of the deodorizing fiber structure and the inorganic particles will decrease, requiring an excessive amount of binder. This will increase the area of the inorganic particle surface covered by the binder, and may result in insufficient deodorizing performance.

Dust retention is measured by conducting a dust test (for example, JIS D 1612-1989 "Test Methods for Automotive Air Cleaners") on a sample of air filter media or air filter under certain conditions. When the pressure loss of the sample reaches a certain level, the mass of test dust accumulated on the air filter media or air filter is calculated from the increase in sample mass, and the mass per unit area of the air filter media or air filter is calculated. The higher the dust retention value, the better the dust collection performance and lifespan of the air filter media or air filter.

From the viewpoint of deodorizing performance, the specific surface area of the inorganic particles is 100 m ² /g or more, more preferably 120 m ² /g or more, and even more preferably 140 m ² /g or more. A specific surface area of less than 100 ^{m 2} /g is undesirable because the deodorizing performance of the deodorizing fiber structure decreases. The specific surface area is preferably 500 m ² /g or less, more preferably 450 m ² /g or less, and even more preferably 400 m ² /g or less. If the specific surface area is more than 500 m ² /g, the average particle size often falls below 1 μm, reducing the adhesion area between the fibers of the deodorizing fiber structure and the inorganic particles. This requires an excess of the binder, which is preferably used to support the inorganic particles, and increases the area of the inorganic particle surface covered by the binder, which may result in insufficient deodorizing performance.

From the viewpoint of deodorizing performance, the pore volume of the inorganic particles is 0.3 ml/g or more, more preferably 0.4 ml/g or more, and even more preferably 0.5 ml/g or more. If the pore volume is less than 0.3 ml/g, the deodorizing performance of the inorganic particles and water-soluble amine compound against aldehydes will be insufficient, which is undesirable. The pore volume is preferably 4.0 ml/g or less, more preferably 3.5 ml/g or less, and even more preferably 3.0 ml/g or less. If the pore volume is greater than 4 ml/g, costs may increase, which may be disadvantageous from an economic standpoint, or the inorganic particles may be difficult to obtain.

Furthermore, the average pore diameter of the inorganic particles is preferably 0.08 nm or more. If the pore diameter is smaller than 0.08 nm, the deodorizing performance of the inorganic particles and water-soluble amine compound against aldehydes may be insufficient.

To ensure aldehyde deodorizing performance, the pH of a 10% by mass dispersion of inorganic particles and water is 6.6 or higher. The pH is more preferably 9.5 or lower. If the pH is lower than 6.6, the aldehyde deodorizing performance of the inorganic particles and water-soluble amine compound will decrease. If the pH is higher than 9.5, the aldehyde deodorizing performance may also decrease.

Examples of water-soluble amine compounds include hydrazines, acid dihydrazides, aliphatic amines, aromatic amines, ureas, and amino acids. From the perspective of deodorizing performance for aldehydes, acid dihydrazides are more preferred as water-soluble amine compounds.

Examples of acid dihydrazides include carbodihydrazide, adipic acid dihydrazide, sebacic acid dihydrazide, dodecanediohydrazide, isophthalic acid dihydrazide, salicylic acid dihydrazide, succinic acid dihydrazide, and glutamic acid dihydrazide.

The amount of water-soluble amine compound supported on the fiber structure is not particularly limited, but is preferably 3% by mass or more and 100% by mass or less relative to the mass of the inorganic particles. If the amount supported is less than 3% by mass, deodorizing performance may be poor, and if the amount supported is more than 100% by mass, deodorizing performance may plateau.

Materials for the fiber structure of the present invention include synthetic fibers such as polyamide fibers, polyester fibers, polyalkylene paraoxybenzoate fibers, polyurethane fibers, polyvinyl alcohol fibers, polyvinylidene chloride fibers, polyvinyl chloride fibers, polyacrylonitrile fibers, polyolefin fibers, and phenolic 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, and silk; recycled pulp from waste paper; regenerated cellulose fibers such as rayon and cupra; and regenerated fibers made from proteins such as collagen, and polysaccharides such as alginic acid, chitin, chitosan, and starch. These fibers may also be modified to have properties such as hydrophilicity or flame retardancy. These fibers may be used in combination of one or more types.

The fiber structure of the present invention is not particularly limited and can be produced, depending on the purpose and application, by imparting strength to a web obtained by a dry method, wet paper-making method, meltblown method, spunbonding method, flash spinning method, airlaid method, electrospinning method, etc., using a physical method such as hydroentangling method, needle punching method, or stitchbonding method, a thermal bonding method such as thermal bonding method, or a chemical bonding method using an adhesive such as resin bonding. The fiber structure may be single-layered or multi-layered. In the case of a multi-layered structure, the method for producing the webs of each layer may be the same or different.

The basis weight of the fiber structure is not particularly limited, but is preferably 30 to 150 g/ ^m2 . If the basis weight of the fiber structure is less than 30 g/ ^m2 , the inorganic particles may not be sufficiently supported, and the deodorizing performance may be too low. If the basis weight of the fiber structure is more than 150 g/ ^m2 , the pressure loss may be too high.

The deodorizing fiber structure of the present invention can be produced by supporting inorganic particles, which serve as a deodorizing agent, and a water-soluble amine compound on a fiber structure. It is preferable to use a binder when supporting the particles.

The binder is not particularly limited and a wide variety of binders can be used, but water-soluble or water-dispersible binders are preferred. Examples of water-soluble binders include polyvinyl alcohol and starch. Examples of water-dispersible binders include poly(meth)acrylic acid esters, polyvinyl acetate, polyvinyl chloride, styrene-acrylic resin, vinyl chloride-acrylic resin, silicone resin, and styrene-butadiene resin.

The amount of binder added is not particularly limited, but is preferably 5 to 40% by mass, based on the solids mass, of the total amount of inorganic particles and water-soluble amine compound supported. When the binder content is 5 to 40% by mass, the amount of inorganic particles and water-soluble amine compound supported is more stable, and it is easier to achieve both high deodorizing performance and low pressure loss.

There are no particular limitations on the method for supporting inorganic particles and a water-soluble amine compound on a fiber structure, as long as it allows the inorganic particles and water-soluble amine compound to adhere as uniformly as possible to the fiber structure. Examples of methods include applying a coating liquid containing a dispersion containing inorganic particles, a water-soluble amine compound, and, if necessary, a binder to a fiber structure by a coating or printing method such as screen printing, roll coating, spraying, dipping, curtain coating, bar coating, air knife printing, hot melt coating, gravure coating, brush coating, or offset printing, and then removing the dispersion medium by drying or other methods to support the particles. Water is preferably used as the dispersion medium.

In the present invention, the total solid content of the inorganic particles, water-soluble amine compound, and optionally binder is not particularly limited, but is preferably 1 to 50 g/ ^m2 relative to the fiber structure. If the solid content is less than 1 g/ ^m2 , the deodorizing performance may become too low. If the solid content is more than 50 g/ ^m2 , the deodorizing performance may plateau and may not be economically viable. A more preferred solid content is 2 to 20 g/ ^m2 .

If necessary, and without departing from the spirit of the present invention, various functions can be added to the fiber structure for the purpose of adding other properties, such as antibacterial, antifungal, antiviral, insect repellent, insecticidal, deodorizing, fragrance, temperature sensing, heat retention, heat storage, heat storage, heat generation, heat absorption, waterproofing, water resistance, water repellency, hydrophobicity, hydrophilicity, dehumidification, humidity control, moisture absorption, oil repellency, lipophilicity, adsorption of oil, etc., and evaporation or sustained release of water or volatile chemicals, etc.

The deodorizing fiber structure of the present invention can be used as an air filter medium or air filter, either alone or after being bonded to other fiber structures, in air treatment devices that use forced air intake and exhaust, such as air conditioners, air purifiers, vacuum cleaners, dehumidifiers, dryers, humidifiers, ventilation fans, electric fans, and heat exchangers, to achieve favorable effects in deodorizing malodorous gases in indoor spaces. Alternatively, the air filter medium of the present invention can be used in an outside air inlet (such as an air vent or window) for natural air intake and exhaust.

The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples. In the examples, "%" and "parts" mean "% by mass" and "parts by mass", respectively, unless otherwise specified.

[Average particle diameter]
The average particle size of the inorganic particles was measured using a laser diffraction/scattering particle distribution measuring device LA-950S2 manufactured by Horiba, Ltd.

[Specific surface area]
The specific surface area of the inorganic particles was measured as the BET specific surface area using a SORPTOMATIC 1900 manufactured by Carlo Erba. The BET method is a gas adsorption method in which gas molecules such as nitrogen ( _N2 ) are adsorbed onto solid particles and the surface area is measured from the amount of adsorption. Specifically, the specific surface area can be determined by measuring the monomolecular adsorption amount VM using the BET equation (Brunauer, Emmet and Teller's equation) from the relationship between the pressure P and the adsorption amount V.

[Pore volume]
The pore volume of the inorganic particles was measured using an AUTOPORE II 9220 manufactured by Micromeritics.

[pH of inorganic particle dispersion]
The pH of the inorganic particle dispersion was measured in accordance with the pH value - room temperature extraction method of the pigment testing method of JIS K 5101-17-2:2004.

Example 1
A coating solution was prepared by blending 12 g of inorganic particles (Mizusawa Chemical Industry Co., Ltd., trade name: Mizukasil (registered trademark) P-526) with an average particle diameter of 7 μm, a specific surface area of 150 ^m /g, a pore volume of 0.6 ml/g, and a pH of 7.0 for the inorganic particle dispersion, 3 g of adipic acid dihydrazide (a reagent manufactured by Tokyo Chemical Industry Co., Ltd.) as a water-soluble amine compound, and 7 g of solids of an acrylic resin emulsion binder as a binder into 20 g of pure water and stirring. A deodorizing fiber structure was prepared by impregnating a polyester spunbond nonwoven fabric (basis weight 50 g/ ^m , thickness 0.5 mm ⁾ with the coating solution while controlling the solids loading, and then drying at 120°C. The total solids loading of the inorganic particles, water-soluble amine compound, and binder on the fiber structure was 20 g/m .

Example 2
^A deodorizing fiber structure was produced in the same manner as in Example 1, except that the inorganic particles used were alumina (manufactured by Nippon Light Metal Co., Ltd., product name: AxSorb AA-101) having an average particle diameter of 2 μm, a specific surface area of 300 m 2 /g, a pore volume of 0.44 ml/g, and a pH of the inorganic particle dispersion of 7.0. The total solids loading of the fiber structure, including the inorganic particles, water-soluble amine compound, and binder, was 20 g/m ² .

Example 3
A deodorizing fiber structure was produced in the same manner as in Example 1, except that sebacate dihydrazide (a reagent manufactured by Tokyo Chemical Industry Co., Ltd.) was used as the water-soluble amine compound. The total solids content of the inorganic particles, water-soluble amine compound, and binder on the fiber structure was 20 g/ ^m² .

Example 4
A deodorizing fiber structure was produced in the same manner as in Example ¹ , except that the inorganic particles used were silicon dioxide (manufactured by Maruo Calcium Co., Ltd., trade name: Finesil X-60) having an average particle diameter of 6.6 μm, a specific surface area of 290 m 2 /g, a pore volume of 1.4 ml/g, and an inorganic particle dispersion pH of 6.7. The total solids loading of the fiber structure, including the inorganic particles, water-soluble amine compound, and binder, was 20 g/m ² .

Example 5
A deodorizing fiber structure was produced in the same manner as in Example ¹ , except that the inorganic particles used were silicon dioxide (manufactured by Tosoh Silica Corporation, product name: NIPGEL (registered trademark) AZ-200) having an average particle size of 2.4 μm, a specific surface area of 300 m 2 /g, a pore volume of 2.0 ml/g, and a pH of 7.0 for the inorganic particle dispersion. The total solids loading of the fiber structure, including the inorganic particles, water-soluble amine compound, and binder, was 20 g/m ² .

Example 6
20 parts by mass of titanium tetraisopropoxide (manufactured by Kojundo Chemical Laboratory Co., Ltd., product name: Tetra-i-propoxytitanium) as a titanium dioxide precursor was added to 50.7 parts by mass of distilled water and 49.3 parts by mass of normal propanol and stirred for 2 hours. After stirring, the mixture was placed in a 200 ml fluororesin pressure vessel and left in a thermostatic chamber set to 100°C for 24 hours to undergo hydrothermal treatment. The pressure vessel was then removed and allowed to cool. The reaction product in the pressure vessel was separated by suction filtration, dried for 6 hours in a dryer set to 80°C, and pulverized using a pulverizer to obtain a powder of titanium dioxide 1. The resulting titanium dioxide 1 had an average particle size of 15 μm, a specific surface area of 230 m ² /g, a pore volume of 0.33 ml/g, and a pH of 6.9.

A deodorizing fiber structure was produced in the same manner as in Example 1, except that titanium dioxide 1 was used as the inorganic particles. The total solid content of the inorganic particles, water-soluble amine compound, and binder carried on the fiber structure was 20 g/ ^m2 .

Example 7
A deodorizing fiber structure was produced in the same manner as in Example 1, except that the inorganic particles used were silicon dioxide having an average particle size of 50 μm, a specific surface area of 230 m ² /g, a pore volume of 0.6 ml/g, and a pH of 7.4 for the inorganic particle dispersion. The total solids adhesion amount of the inorganic particles, water-soluble amine compound, and binder to the fiber structure was 20 g/m ² .

(Example 8)
A deodorizing fiber structure was produced in the same manner as in Example 1, except that the inorganic particles used were silicon dioxide having an average particle diameter of 3 μm, a specific surface area of 100 ^m /g, a pore volume of 0.4 ml/g, and a pH of 7.2 for the inorganic particle dispersion. The total solids adhesion amount of the inorganic particles, water-soluble amine compound, and binder to the fiber structure was ²⁰ g/m .

Example 9
A deodorizing fiber structure was produced in the same manner as in Example 1, except that the inorganic particles were silicon dioxide having an average particle size of 5 μm, a specific surface area of 200 ^m /g, a pore volume of 0.3 ml/g, and a pH of the inorganic particle dispersion of ^7.2 . The total solids adhesion amount of the inorganic particles, water-soluble amine compound, and binder to the fiber structure was 20 g/m .

(Comparative Example 1)
A deodorizing fiber structure was produced in the same manner as in Example ¹ , except that the inorganic particles used were silicon dioxide (manufactured by EVONIK GmbH (Germany), product name: Carplex (registered trademark) FPS-101) having an average particle diameter of 2 μm, a specific surface area of 260 m 2 /g, a pore volume of 0.89 ml/g, and a pH of 6.5 for the inorganic particle dispersion. The total solids loading of the fiber structure, including the inorganic particles, water-soluble amine compound, and binder, was 20 g/m ² .

(Comparative Example 2)
A deodorizing fiber structure was produced in the same manner as in Example 1, except that the inorganic particles used were silicon dioxide (manufactured by Mizusawa Industrial Chemicals, Ltd., trade name: Mizukasil (registered trademark) ^P -527) having an average particle diameter of 2 μm, a specific surface area of 55 m 2 /g, a pore volume of 0.1 ml/g, and an inorganic particle dispersion pH of 6.5. The total solids loading of the fiber structure, including the inorganic particles, water-soluble amine compound, and binder, was 20 g/m ² .

(Comparative Example 3)
A deodorizing fiber structure was produced in the same manner as in Example 1, except that the inorganic particles used were silicon dioxide having an average particle diameter of 105 μm, a specific surface area of 180 m ² /g, a pore volume of 1.7 ml/g, and a pH of the inorganic particle dispersion of 7.6. The total solids adhesion amount of the inorganic particles, water-soluble amine compound, and binder to the fiber structure was 20 g/m ² .

(Comparative Example 4)
A deodorizing fiber structure was produced in the same manner as in Example ¹ , except that the inorganic particles used were silicon dioxide (manufactured by Nissan Chemical Industries, Ltd., product name: Lightstar (registered trademark)) having an average particle diameter of 0.7 μm, a specific surface area of 250 m /g, a pore volume of 1.0 ml/g, and an inorganic particle dispersion pH of 7.0. The total solids adhesion amount of the inorganic particles, water-soluble amine compound, and binder to the fiber structure was ²⁰ g/m .

(Comparative Example 5)
A deodorizing fiber structure was produced in the same manner as in Example ¹ , except that the inorganic particles used were zeolite (manufactured by Tosoh Corporation, product name: Zeolite HSZ385HUA) having an average particle diameter of 4 μm, a specific surface area of 600 m /g, a pore volume of 0.42 ml/g, and a pH of the inorganic particle dispersion of 7.3. After coating the fiber structure with the inorganic particles, water-soluble amine compound, and binder, the solid adhesion amount to the ^fiber structure was 20 g/m .

[Acetaldehyde deodorizing performance test]
The prepared deodorizing fiber structures were cut into 5 cm x 5 cm pieces as air filter media samples and tested individually. The samples were placed in 10-liter odor bags and sealed, and 10 liters of 10 ppm acetaldehyde gas was injected. The acetaldehyde concentration in the odor bags after 30 minutes was measured using a gas detector tube. The acetaldehyde concentration in the odor bags after 30 minutes was evaluated on a three-point scale: "◎: 0 ppm or more but less than 1.5 ppm,""◯: 1.5 ppm or more but less than 3 ppm," and "×: 3 ppm or more." In the present invention, ◎ and ○ are the subject of the invention. A ◎ rating is preferable, indicating better acetaldehyde deodorizing performance.

The evaluation results are shown in Table 1.

As can be seen from Table 1, Examples 1 to 9 are deodorizing fiber structures using inorganic particles whose average particle diameter, specific surface area, pore volume, and pH of the inorganic particle dispersion are all within the specified physical properties of the present invention, and all of them exhibited good acetaldehyde deodorizing performance.

However, the deodorizing fiber structure of Comparative Example 1, which uses inorganic particles whose dispersion pH is below 6.6, and the deodorizing fiber structure of Comparative Example 2, which uses inorganic particles whose dispersion pH is below 6.6, has a specific surface area of less than 100 m ² /g, and a pore volume of less than 0.3 ml /g, had poor acetaldehyde deodorizing performance.On the other hand, the deodorizing fiber structure of Comparative Example 4, which uses inorganic particles whose average particle diameter is less than 1 μm, had good acetaldehyde deodorizing performance, but generated a lot of dust when handling the inorganic particles, which caused problems when manufacturing the filter medium, and was not preferred.In addition, the deodorizing fiber structure of Comparative Example 3, which uses inorganic particles whose average particle diameter is more than 50 μm, had a large average particle diameter of the inorganic particles, so it was difficult to control the solid content when impregnating and coating the coating liquid, and the deodorizing fiber structure could not be stably produced, and was not preferred. Furthermore, the zeolite used in Comparative Example 5 is an inorganic particle whose average particle diameter, specific surface area, pore volume, and pH of the inorganic particle dispersion all satisfy the specified physical properties of the present invention, and the deodorizing fiber structure of Comparative Example 5 is a deodorizing fiber structure using this zeolite. However, compared to silicon dioxide, alumina, and titanium dioxide, the material cost is generally high and it is not very preferable from an economic standpoint.

These results demonstrate that the deodorizing fiber structure of the present invention has excellent deodorizing performance for aldehydes such as acetaldehyde, and uses inorganic particles that are easy to handle and economical when supported on the fiber structure.

The deodorizing fiber structure of the present invention can be used in air filters used in air conditioners and air purifiers used in buildings, factories, automobiles, and ordinary homes.

Claims (3)

A deodorizing fiber structure comprising inorganic particles and a water-soluble amine compound supported on a fiber structure, wherein the inorganic particles are porous particles and are one or more types of inorganic particles selected from the group consisting of silicon dioxide, alumina, and titanium dioxide, the inorganic particles have an average particle size of 1 to 50 μm, a specific surface area of 100 m ² /g or more, a pore volume of 0.3 ml/g or more, and a pH of a 10 mass% dispersion of the inorganic particles in water is 6.6 or more. An air filter medium using the deodorizing fiber structure of claim 1. An air filter using the deodorizing fiber structure described in claim 1.