Adsorbent, method for producing the same, filter medium, and air filter

Abstract

An object of the present invention is to provide an adsorbent, a filter medium, and an air filter that have excellent aldehyde removal performance and little deterioration over time. The present invention is an adsorbent characterized in that an amine compound and a compound having a thioether group in a functional group are loaded at least on an inorganic porous body.

Description

Technical Field

[0001] The present invention relates to an adsorbent, a filter medium, and an air filter. Background Art

[0002] Due to the increasing aspiration for health and comfort, the demand for improving the living environment has increased. There are various pollutants in indoor air, and among these, aldehydes such as acetaldehyde are particularly problematic as pollutants. Acetaldehyde is a representative malodorous component contained in tobacco smoke and automobile exhaust, has a low odor threshold, and is likely to be smelled even at low concentrations.

[0003] Conventionally, activated carbon having a large surface area and pore volume has generally been used to remove malodorous components in the air. However, the equilibrium adsorption amount of lower aliphatic aldehydes on activated carbon is significantly smaller than that of other malodorous components, and it does not have practical performance.

[0004] As a technique for removing lower aliphatic aldehydes, a method of improving the performance by loading an amine compound on activated carbon has been proposed (see Patent Document 1).

[0005] On the other hand, in conventional adsorbents, these amine compounds are easily oxidized by oxygen in the air, thereby reducing the effectiveness of the chemisorption action on aldehydes, and there is a problem that the aldehyde removal performance cannot be maintained for a long time.

[0006] In order to solve this problem, a technique has been proposed in which a hydrazide compound as an amine compound and a compound having a mercapto group in a functional group as an antioxidant are loaded on silica gel, thereby suppressing the oxidation of the amine-based compound and suppressing the deterioration of the aldehyde removal performance over time (see Patent Document 2).

[0007] Prior Art Documents

[0008] Patent Documents

[0009] Patent Document 1: Japanese Patent Laid-Open No. 5-317703

[0010] Patent Document 2: International Publication No. 2015 / 037483 Summary of the Invention

[0011] Problems to be Solved by the Invention

[0012] However, although an adsorbent obtained by loading a compound having a mercapto group in a functional group on silica gel has been confirmed to have a performance of suppressing deterioration over time, further improvement in performance is desired. Therefore, an object of the present invention is to provide an adsorbent, a filter medium, and an air filter having excellent aldehyde removal performance and small deterioration over time.

[0013] Means for Solving the Problems

[0014] The present invention relates to an adsorbent, which is characterized in that an amine compound and a compound having a thioether group in a functional group are at least supported on an inorganic porous body.

[0015] In addition, the present invention relates to a filter medium, which is characterized in that the adsorbent of the present invention is used.

[0016] In addition, the present invention relates to an air filter, which is characterized in that the filter medium of the present invention is used.

[0017] In addition, the present invention relates to a method for manufacturing an adsorbent, which is characterized in that a compound having a thioether group in a functional group and an amine compound are dissolved in water, and the obtained solution is loaded on an inorganic porous body and dried.

[0018] Effects of the Invention

[0019] By at least loading an amine compound and a compound having a thioether group in a functional group on an inorganic porous body, the present invention can provide an adsorbent, a filter medium, and an air filter having excellent aldehyde removal performance and little deterioration over time. Detailed Embodiments

[0020] Hereinafter, the present invention will be described in detail. It should be noted that in the present invention, "above" means the same as or greater than the value shown herein. In addition, "below" means the same as or less than the value shown herein.

[0021] The adsorbent of the present invention has an inorganic porous body. By using an inorganic porous body, while obtaining a surface area capable of contacting the processing air, a sufficient amount of the following-mentioned medicament can be loaded, and the aldehyde removal efficiency can be improved.

[0022] As the inorganic porous body used in the present invention, a substance selected from activated carbon, zeolite, activated alumina, silica gel, activated clay, aluminum silicate, and magnesium silicate can be preferably used. Two or more selected therefrom can also be used in combination.

[0023] Among the inorganic porous bodies, porous silica does not react with the following-mentioned amine compound and is excellent in suppressing the deterioration of the amine compound supported on the porous silica. In addition, porous silica has strong hydrophilicity and high affinity with water-soluble medicaments such as amine compounds. From the viewpoint of making the aldehyde adsorption performance of the adsorbent more excellent, the inorganic porous body is also preferably porous silica.

[0024] In addition, the inorganic porous body used in the present invention is preferably granular. If it is granular, the performance aspect and the economic aspect can be effectively balanced. The specific surface area of the fibrous inorganic porous body increases, the contact efficiency with the target gas becomes high, and the performance aspect (removal efficiency) is good, but the price is high.

[0025] The average particle diameter of the inorganic porous body is preferably 1 μm or more and 1000 μm or less. The average particle diameter referred to herein means the mass average diameter specified in the activated carbon test method of JIS-K1474 (2014). By making the average particle diameter of the inorganic porous body 1000 μm or less, more preferably 600 μm or less, the adsorption rate of the lower aliphatic aldehyde gas by the adsorbent can be accelerated. In addition, it is easy to manufacture, has excellent strength, is difficult to be damaged, and can also suppress the generation of dust caused by damage. On the other hand, by making it 50 μm or more, more preferably 100 μm or more, the scattering of the inorganic porous body can be prevented, and the processability and workability can be made excellent.

[0026] As the average pore diameter of the inorganic porous body in the present invention, it is preferably 4 nm or more and 50 nm or less. The average pore diameter in the present invention means the peak diameter obtained by the BJH method. More specifically, it is obtained by using the adsorption-side isotherm obtained by the nitrogen adsorption method at 77 Kelvin (liquid nitrogen temperature). By making the average pore diameter of the inorganic porous body 50 nm or less, more preferably 30 nm or less, while suppressing the reduction of the mechanical strength of the inorganic porous body, the specific surface area of the inorganic porous body can be increased, and the low-boiling aldehyde removal performance of the adsorbent can be made more excellent. In addition, by making the average pore diameter of the inorganic porous body 4 nm or more, more preferably 5 nm or more, it can promote the entry of amine compounds and VOC gases into the pores of the granular inorganic porous body.

[0027] The specific surface area of the inorganic porous body used in the present invention is preferably 30 m 2 , 2 , 2 , 2 , 2 / g or more and 1000 m 2 / g or less. By making the specific surface area of the inorganic porous body 30 m 2 / g or more, more preferably 50 m 2 / g or more, as the reaction site of the amine compound supported on the inorganic porous body, the effective area is increased, and the reaction rate between the adsorbent and the VOC gas to be removed is increased. In addition, by making the BET specific surface area of the inorganic porous body 1000 m 2 / g or less, the reduction of processability caused by the reduction of the mechanical strength of the inorganic porous body can be suppressed, and at the same time, the unintentional adsorption of VOC gas causing secondary odor on the adsorbent can be suppressed.

[0028] It is important for the adsorbent of the present invention to support an amine compound on the inorganic porous body. Through the amine compound, aldehyde-based odor substances can be effectively adsorbed.

[0029] As the amine compound, aniline having an amino group, hydrazides, benzylamine, naphthylamine, cyclohexylamine, (iso)propanolamine, ethanolamine, diethylenetriamine, triethylenetetramine, styrene ethyl methacrylate amine, styrene acrylamide, etc., which are primary amine compounds, compounds, monomers, oligomers, polymers, or derivatives containing an amino group derived from these compounds, etc. can be used.

[0030] As amine compounds other than primary amine compounds, for example, secondary amine compounds include pyrazoles such as 3,5-dimethylpyrazole, 3-methyl-5-pyrazolone, 1,2,3-triazole, 1,2,4-triazole, 3-n-butyl-1,2,4-triazole, 3,5-dimethyl-1,2,4-triazole, 3,5-di-n-butyl-1,2,4-triazole, etc., oxazines, secondary amine compounds of alkyl types such as dipropylamine and dibutylamine, and in addition, cyclic secondary amine compounds such as piperidine, piperazine, and pyrrolidine.

[0031] In addition, as secondary amine compounds, secondary amine compounds having an amide bond or a urea bond are preferred in terms of preventing the re-release of aldehydes. Among them, from the viewpoints of high safety, no amine odor generation, water solubility, and good processability, 1,3-dimethylurea and ethylene urea are more preferred.

[0032] As tertiary amine compounds, vinylbenzyl dimethylamine, vinylbenzyl diethylamine, styrene acrylic acid diethylamine, styrene methacrylic acid diethylamine, styrene acrylic acid dimethylamine, styrene methacrylic acid dimethylamine, styrene methacrylic acid ethyl dimethylamine, styrene acrylic acid ethyl dimethylamine, styrene methacrylic acid ethyl diethylamine, styrene acrylic acid ethyl diethylamine, triethylamine, etc., compounds, monomers, oligomers, polymers, or tertiary amine compounds derived from these compounds, etc. can be cited.

[0033] For the reason that the performance of suppressing the detachment of high-boiling aldehydes from the adsorbent is more excellent, among these, primary amine compounds having an amino group are preferred, and among them, hydrazides are more preferred.

[0034] Hydrazides are compounds having a hydrazide group represented by -CO-NHNH2 derived from carboxylic acid and hydrazine. At the α-position of the hydrazide terminal, a nitrogen atom having a lone pair of electrons is further bonded, whereby the nucleophilic reactivity is significantly improved. It is believed that this lone pair of electrons nucleophilically attacks the carbonyl carbon atom of the aldehyde compound and reacts, immobilizing the aldehyde compound as a hydrazide derivative, and thus the adsorption performance of the aldehyde compound can be exhibited.

[0035] Among aldehyde compounds, acetaldehyde has an electron-donating alkyl group at the α-position of the carbonyl carbon, so the electrophilicity of the carbonyl carbon is low and it is difficult to be chemically adsorbed. As described above, the hydrazides preferably used in the adsorbent used in the present invention have high nucleophilic reactivity, so they also exhibit good chemical adsorption performance for acetaldehyde.

[0036] In addition, from the viewpoint of being easily loaded and processed on an inorganic porous body, the hydrazides are preferably water-soluble hydrazides.

[0037] Here, the water-soluble hydrazides refer to hydrazides that dissolve 0.5 mass% or more in water (25 °C).

[0038] As the hydrazide compounds used in the present invention, for example, as monohydrazides having 1 hydrazide group in the molecule, formylhydrazine, acetylhydrazine, propionylhydrazine, and benzoylhydrazine can be mentioned. As dihydrazides having 2 hydrazide groups in the molecule, dihydrazide carbonate, glutamic acid dihydrazide, succinic acid dihydrazide, adipic acid dihydrazide, dodecanedioic acid dihydrazide, fumaric acid dihydrazide, maleic acid dihydrazide, and terephthalic acid dihydrazide can be mentioned. And as polyhydrazides having 3 or more hydrazide groups in the molecule, polyacrylic acid hydrazide can be mentioned.

[0039] Among them, from the viewpoint of adsorption performance, dihydrazide carbonate, succinic acid dihydrazide, and adipic acid dihydrazide are preferably used. In addition, by using adipic acid dihydrazide, the effect of excellent adsorption capacity for acetaldehyde is particularly exhibited.

[0040] The loading amount of the amine compound is preferably 0.5 parts by mass or more and 30 parts by mass or less with respect to 100 parts by mass of the inorganic porous body. By making the loading amount of the amine compound 0.5 parts by mass or more, more preferably 2.0 parts by mass or more, the practical effect of improving the removal efficiency and adsorption capacity of aldehydes can be obtained. On the other hand, by making the loading amount of the amine compound 30 parts by mass or less, more preferably 20 parts by mass or less, crystallization of the amine compound can be suppressed from clogging the pores of the inorganic porous body and reducing the adsorption rate, and at the same time, it can cause dust to fall off.

[0041] In addition, importantly, the adsorbent of the present invention also supports a compound having a thioether group (-S-) in the functional group on the inorganic porous body (hereinafter also referred to as "thioether compound"). Thereby, an adsorbent capable of suppressing the deterioration of aldehyde removal performance over time can be obtained. It is considered that the main reason for the deterioration of aldehyde removal performance over time is the decomposition reaction of the amine compound promoted by the metal present on the pore surface of the inorganic porous body, and this tendency is particularly significant when the amine compound is a hydrazide compound. In this regard, the thioether group has reactivity with the metal, and thus it is considered that the above decomposition reaction can be suppressed. Further, the reason is considered to be that the thioether group has a property of being easily oxidized by itself, and by supporting the thioether compound, there is an effect of preventing the amine compound having excellent reactivity with aldehydes from being oxidized and decomposed.

[0042] Examples of the thioether compound used in the present invention include methionine compounds in addition to dimethyl sulfide and diethyl sulfide. Specific examples of methionine compounds include one or more selected from L-methionine, D-methionine, D,L-methionine and their salts, and methionine derivatives such as esters of the carboxyl group and amides of the carboxyl group contained in these methionines. Among these, from the viewpoints of low cost and excellent heat resistance, methionine is preferred. Among them, L-methionine exists in a large proportion in nature, so it is inexpensive and preferably used.

[0043] The loading amount of the thioether compound is preferably 0.5 parts by mass or more and 20 parts by mass or less relative to 100 parts by mass of the inorganic porous body. By making the loading amount of the thioether compound 0.5 parts by mass or more, more preferably 1.0 parts by mass or more, it is possible to sufficiently react with the metal component attached to the pore surface. On the other hand, by making it 20 parts by mass or less, more preferably 10 parts by mass or less, it is possible to prevent the pores of the inorganic porous body from being blocked and the adsorption rate from decreasing.

[0044] As a method for supporting the amine compound and the thioether compound on the inorganic porous body, a method can be cited in which the amine compound and the thioether compound are dissolved in water, the obtained aqueous solution is loaded on the inorganic porous body, and then the inorganic porous body is dried.

[0045] The gas adsorbent of the present invention preferably has an aqueous solution pH (hydrogen ion exponent) of 3.0 or more and 7.5 or less when 5 g of it is dispersed in 100 g of water at 25°C. Thereby, the removal performance of aldehydes is improved. By making the pH of the aqueous solution 7.5 or less, more preferably 6.5 or less, the intermediate generated by the reaction of the non-bonding electron pair of the amine-based compound nucleophilically attacking the carbonyl carbon atom of the aldehyde is protonated at the acidic reaction site, is easily dehydrated, and the immobilization reaction on the derivative proceeds sufficiently. In addition, by making the pH of the aqueous solution 3.0 or more, more preferably 4.0 or more, the activity of the non-bonding electron pair of the amine-based compound nucleophilically attacking the carbonyl carbon atom of the aldehyde can be sufficiently maintained.

[0046] The pH of the adsorbent can be adjusted by loading at least one acid selected from organic acids and inorganic acids (hereinafter also referred to as "organic / inorganic acids") on the adsorbent. As the organic / inorganic acid, an acid that does not generate odor by itself is preferred.

[0047] Specific examples of the organic acid include adipic acid, succinic anhydride, p-aminobenzenesulfonic acid, malic acid, citric acid, amino acids, etc. When dihydrazide adipate is used as the amine-based compound and infiltrated and processed in the inorganic porous body in the form of an aqueous dispersion, adipic acid can be preferably used. Adipic acid stably maintains the balance of the dispersion of dihydrazide adipate, and in addition, there is no generation of odor and no manifestation of hygroscopicity, so it is preferably used.

[0048] As the inorganic acid, phosphoric acid is preferably used. Phosphoric acid forms an insoluble salt with dissolved heavy metals such as iron that promotes the oxidation of the thioether group, and can insolubilize the heavy metals, so it is preferably used.

[0049] As a method of loading the organic / inorganic acid on the adsorbent, in the case of infiltrating and processing the amine-based compound and the thioether compound in the form of an aqueous dispersion, the organic / inorganic acid is also preferably added after being mixed in the aqueous dispersion.

[0050] Next, the filter medium of the present invention is characterized by using the adsorbent of the present invention.

[0051] The filter medium of the present invention is preferably obtained by sandwiching the adsorbent of the present invention with a breathable sheet (hereinafter also referred to as "breathable sheet").

[0052] As the breathable sheet, a fibrous structure is preferred. Specifically, cotton-like materials, knitted / woven fabrics, non-woven fabrics, paper, and other three-dimensional meshes can be cited. In addition, laminates thereof can also be used. By adopting such a structure, it is possible to ensure breathability while obtaining a large surface area. From the viewpoint of being used as an air filter, non-woven fabric is preferably used.

[0053] As the fibers for forming the breathable sheet, natural fibers, synthetic fibers, inorganic fibers such as glass fibers and metal fibers can be cited. Among them, synthetic fibers containing a thermoplastic resin capable of melt spinning are preferably used. Examples of the thermoplastic resin for forming the synthetic fibers include polyester, polyamide, polyolefin, polyacrylic acid, vinylon (polyvinyl alcohol), polystyrene, polyvinyl chloride, polyvinylidene chloride, and polylactic acid, etc., which can be selected according to the use and so on. In addition, multiple kinds can also be used in combination.

[0054] The fiber diameter of the fibers constituting the breathable sheet can be selected according to the target breathability and dust collection performance in the use as an air filter, and is preferably 1 μm or more and 2000 μm or less. By making the fiber diameter 1 μm or more, more preferably 5 μm or more, it is possible to prevent the adsorbent from clogging on the surface of the fiber structure and prevent the reduction of breathability. In addition, by making the fiber diameter 2000 μm or less, more preferably 100 μm or less, it is possible to prevent the reduction of the loading capacity of the adsorbent and the reduction of the contact efficiency with the treated air due to the reduction of the fiber surface area.

[0055] As the weight per unit area of the breathable sheet, it is preferably 10 g / m 2 or more and 500 g / m 2 or less. By making the weight per unit area 10 g / m 2 or more, sufficient strength for withstanding the processing for loading the adsorbent is obtained, and the rigidity required to maintain the filter structure when air passes through is obtained. In addition, by making the weight per unit area 500 g / m 2 or less, more preferably 200 g / m 2 or less, it is possible to uniformly load the adsorbent into the interior of the breathable sheet, and in addition, the processability when secondary processed into a pleated shape or a honeycomb shape is also excellent.

[0056] At least one sheet of the breathable sheet is preferably subjected to electret treatment. By performing electret treatment, it is possible to capture fine dust of submicron size and nanometer size that is usually difficult to remove by electrostatic force.

[0057] As the material constituting such an electret-treated breathable sheet, polyolefin resins such as polypropylene, polyethylene, polystyrene, polybutylene terephthalate, and polytetrafluoroethylene, aromatic polyester resins such as polyethylene terephthalate, and materials with high resistivity such as polycarbonate resin are preferably used.

[0058] In the filter medium of the present invention, the adsorbent is preferably fixed on the breathable sheet by a thermoplastic resin. By using a thermoplastic resin as the binder resin, it is possible to firmly fix the adsorbent on the breathable sheet while preventing the adsorbent from being covered by the binder and reducing its function.

[0059] As the thermoplastic resin for fixing the adsorbent of the present invention on the air-permeable sheet, thermoplastic resins such as EVA-based, polyester-based, polyamide-based, and low-density polyethylene-based resins can be used.

[0060] As a method for fixing the adsorbent on the air-permeable sheet, it is preferable to use a method in which a mixed powder of the adsorbent of the present invention and a thermoplastic resin is dispersed on the air-permeable sheet, and then another air-permeable sheet is further laminated and hot-pressed to integrate them. By adopting this method, it is possible to prevent the surface of the adsorbent of the present invention from being covered by the thermoplastic resin and the function from being reduced, which is advantageous in terms of the adsorption rate and can extremely effectively exhibit the adsorption capacity.

[0061] The loading amount of the adsorbent in the filter medium of the present invention is preferably 5 g / m 2 or more and 300 g / m 2 or less. By making the loading amount 5 g / m 2 or more, more preferably 10 g / m 2 or more, it is possible to obtain the actual effect of improving the removal efficiency and adsorption capacity of aldehydes. In addition, by making the loading amount 300 g / m 2 or less, more preferably 200 g / m 2 or less, it is possible to prevent the adsorbent from clogging on the surface of the air-permeable adsorption sheet and suppress the reduction of air permeability.

[0062] In addition, the filter medium of the present invention can also carry granular activated carbon in addition to the adsorbent of the present invention. By carrying granular activated carbon, it is possible to remove VOC gases other than aldehyde gas and adsorb and remove all VOC gases.

[0063] The air filter of the present invention is characterized by using the filter medium of the present invention.

[0064] As its shape, it can be directly used in a planar shape, and it is also preferable to adopt a corrugated type or a honeycomb type. The corrugated type can increase the contact area of the treated air and improve the capture efficiency in the use as a straight-through flow type filter, and the honeycomb type can achieve the same effects in the use as a parallel flow type filter, while realizing low pressure loss.

[0065] In addition, it is a preferable method to accommodate the filter medium of the present invention in a housing for the air filter of the present invention in terms of air treatment efficiency and processability.

[0066] Examples

[0067] [Measurement method]

[0068] (1) pH (hydrogen ion index) of the adsorbent

[0069] With respect to 100 g of pure water at a temperature of 25°C, 5 g of the impregnated adsorbent was added, and after gently stirring, it was left for 10 minutes. The pH of the resulting aqueous solution was measured using a pH meter (Ecoscan pH5 manufactured by Radiometer). The measurement was carried out 3 times, and the average value was used.

[0070] (2) Loading method of amine compound and thioether compound

[0071] An aqueous solution mixed with an amine compound and a thioether compound was impregnated and dried in an inorganic porous body for preparation.

[0072] (3) Loading per unit area of adsorbent and thermoplastic resin (g / m 2 )

[0073] The mixed powder obtained by mixing and stirring the adsorbent and the thermoplastic resin was spread on a breathable sheet, and then another breathable sheet was further laminated and hot-pressed to be integrated. The total weight per unit area was measured, and the weight per unit area of the two breathable sheets was subtracted from the total weight per unit area. The obtained value was multiplied by the feeding ratio of each component, and the respective loadings of the adsorbent and the thermoplastic resin with respect to the entire filter material were recorded.

[0074] (4) Acetaldehyde removal performance

[0075] A 12 cm × 12 cm flat filter material was installed on a 10 cm × 10 cm experimental pipe, and air at a temperature of 23°C and a humidity of 50% RH was sent into the pipe at a speed of 0.2 m / sec. Further, acetaldehyde (also expressed as C2H4O) was added from the upstream side through a standard gas cylinder so that the upstream concentration reached 10 ppm. Air was sampled on the upstream side and the downstream side of the filter material, and an infrared absorption type continuous monitor was used to measure the respective acetaldehyde concentrations over time. The removal efficiency was calculated by the following formula.

[0076] Removal efficiency (%) = [(C0 - C) / C0] × 100

[0077] Where,

[0078] C0: Acetaldehyde concentration on the upstream side (10 ppm)

[0079] C: Acetaldehyde concentration on the downstream side (ppm)

[0080] The removal efficiency 100 seconds after the start of acetaldehyde addition was recorded as the initial removal efficiency. If the initial removal efficiency of acetaldehyde just after the sample was prepared was 40% or more, it was considered qualified.

[0081] In addition, the removal efficiency is measured over time, and after 100 seconds, the total adsorption amount (the increase in the mass (g) of the aforementioned flat filter material) when the removal efficiency is reduced to 5% is divided by the pipe area (10 cm × 10 cm), and converted to an average of 1 m 2 , and used as the adsorption capacity (g / m 2 ) for evaluation.

[0082] (5) Aging test over time

[0083] The flat gas adsorption sheet is placed in an environment with a temperature of 85°C and a humidity set to 85% RH. After standing for 3 days after sample preparation, it is installed on the experimental pipe, and the acetaldehyde removal performance is evaluated by the method described in (4) above.

[0084] In addition, the reduction rate of the adsorption capacity in the aging test over time is calculated by the following formula.

[0085] Reduction rate of adsorption capacity (%) = [((adsorption capacity just after sample preparation) - (adsorption capacity after aging test over time)) / (adsorption capacity just after sample preparation)] × 100

[0086] If the reduction rate of the adsorption capacity obtained by the aging test over time is 50% or less, it is evaluated as qualified.

[0087] (6) Heat resistance test

[0088] The flat gas adsorption sheet is placed in an environment with a temperature of 120°C and a humidity set to 25% RH. After standing for 1 day after sample preparation, it is installed on the experimental pipe, and the acetaldehyde removal performance is evaluated by the method described in (4) above.

[0089] In addition, the reduction rate of the adsorption capacity obtained by the heat resistance test is calculated by the following formula.

[0090] Reduction rate of adsorption capacity (%) = [((adsorption capacity just after sample preparation) - (adsorption capacity after heat resistance test)) / (adsorption capacity just after sample preparation)] × 100

[0091] If the reduction rate of the adsorption capacity obtained by the heat resistance test is 50% or less, it is evaluated as "excellent".

[0092] [Example 1] (Adsorbent A)

[0093] (Inorganic porous body)

[0094] As the inorganic porous body, porous silica with an average particle size of 300 μm (Fuji Silysia Chemical Ltd.) is used.

[0095] ​

[0096] Adipic dihydrazide (manufactured by Otsuka Chemical Co., Ltd.) was used.

[0097] (Thioether compound)

[0098] L-Methionine (manufactured by Wako Pure Chemical Industries, Ltd.) was used.

[0099] (Preparation of adsorbent)

[0100] 5% by mass of the above amine compound and 2% by mass of the above thioether compound were dissolved in water, and the resulting aqueous solution was mixed with an inorganic porous body and dried to prepare adsorbent A. The pH of adsorbent A when 5 g was dispersed in 100 g of water was 6.3.

[0101] (Ventilated sheet for upstream side)

[0102] The ventilated sheet located on the upstream side with respect to the air flow uses a chemical-bonded nonwoven fabric having a basis weight of 50 g / m² containing 16.5% by mass of vinylon (polyvinyl alcohol) fibers with a single fiber fineness of 1.5 dtex, 22% by mass of vinylon (polyvinyl alcohol) fibers with a single fiber fineness of 7.1 dtex, 16.5% by mass of polyethylene terephthalate fibers with a single fiber fineness of 2.0 dtex, and 45% by mass of an acrylic resin binder containing a phosphorus-based flame retardant. 2

[0103] (Ventilated sheet for downstream side)

[0104] The ventilated sheet located on the downstream side with respect to the air flow uses an electret-processed meltblown nonwoven fabric containing polypropylene fibers with a basis weight of 20 g / m². 2

[0105] (Hot melt resin)

[0106] Low-density polyethylene (manufactured by Tokyo Ink Co., Ltd., melting point 98 - 104°C) was used.

[0107] (Manufacture of filter medium)

[0108] The above adsorbent and the hot melt resin were mixed so that the mass ratio reached 2:1, stirred until homogeneous, spread on the ventilated sheet for the downstream side, and further covered with the ventilated sheet for the upstream side and hot-pressed to produce filter medium A.

[0109] [Example 2] (Adsorbent B)

[0110] (Inorganic porous body)

[0111] The same inorganic porous body as that used in Example 1 (adsorbent A) was used.

[0112] (Amine compound)

[0113] The same amine compound as used in Example 1 (Adsorbent A) was used.

[0114] (Sulfide compound)

[0115] Diethyl sulfide (manufactured by Tokyo Chemical Industry Co., Ltd.) was used.

[0116] (Preparation of adsorbent)

[0117] 5% by mass of the above amine compound and 2% by mass of the above sulfide compound were dissolved in water, and the resulting aqueous solution was mixed with an inorganic porous body and dried to prepare Adsorbent B. The pH of Adsorbent B when 5 g was dispersed in 100 g of water was 6.4.

[0118] (Manufacture of filter medium)

[0119] The same materials as used in Example 1 were used for the air-permeable sheet for the upstream side, the air-permeable sheet for the downstream side, and the heat-sealing resin. As the adsorbent, Adsorbent B was used, and a filter medium B was produced in the same manner as in Example 1 except for this.

[0120] [Example 3] (Adsorbent C)

[0121] (Inorganic porous body)

[0122] The same inorganic porous body as used in Example 1 (Adsorbent A) was used.

[0123] (Amine compound)

[0124] 1,3-Dimethylurea (manufactured by Nacalai Tesque, Inc.) was used.

[0125] (Sulfide compound)

[0126] The same sulfide compound as used in Example 1 (Adsorbent A) was used.

[0127] (Preparation of adsorbent)

[0128] 5% by mass of the above amine compound and 2% by mass of the above sulfide compound were dissolved in water, and the resulting aqueous solution was mixed with an inorganic porous body and dried to prepare Adsorbent C. The pH of Adsorbent C when 5 g was dispersed in 100 g of water was 6.4.

[0129] (Manufacture of filter medium)

[0130] For the air-permeable sheet for the upstream side, the air-permeable sheet for the downstream side, the heat-sealing resin uses the same substance as that used in Example 1, and as the adsorbent, Adsorbent C is used. Except for this, the filter medium C is produced in the same manner as in Example 1.

[0131] [Example 4] (Adsorbent D)

[0132] (Inorganic porous body)

[0133] The same inorganic porous body as that used in Example 1 (Adsorbent A) is used.

[0134] (Amine compound)

[0135] Dicarbohydrazide (manufactured by Nippon Finechem Co., Ltd.) is used.

[0136] (Sulfide compound)

[0137] The same sulfide compound as that used in Example 1 (Adsorbent A) is used.

[0138] (Preparation of adsorbent)

[0139] 5% by mass of the above amine compound and 2% by mass of the above sulfide compound are dissolved in water, and the obtained aqueous solution is mixed with the inorganic porous body and dried to prepare Adsorbent D. The pH of Adsorbent D when 5 g is dispersed in 100 g of water is 6.5.

[0140] (Manufacture of filter medium)

[0141] For the air-permeable sheet for the upstream side, the air-permeable sheet for the downstream side, the heat-sealing resin uses the same substance as that used in Example 1, and as the adsorbent, Adsorbent D is used. Except for this, the filter medium D is produced in the same manner as in Example 1.

[0142] [Example 5] (Adsorbent E)

[0143] (Inorganic porous body)

[0144] The same inorganic porous body as that used in Example 1 (Adsorbent A) is used.

[0145] (Amine compound)

[0146] Succinic dihydrazide (manufactured by Nippon Finechem Co., Ltd.) is used.

[0147] (Sulfide compound)

[0148] The same sulfide compound as that used in Example 1 (Adsorbent A) is used.

[0149] (Preparation of adsorbent)

[0150] Dissolve 5% by mass of the above amine compound and 2% by mass of the above sulfide compound in water, mix the resulting aqueous solution with an inorganic porous body and dry it to prepare adsorbent E. The pH of adsorbent E when 5 g is dispersed in 100 g of water is 6.4.

[0151] (Manufacture of filter medium)

[0152] Use the same materials for the air-permeable sheet for the upstream side, the air-permeable sheet for the downstream side, and the hot-melt resin as those used in Example 1. As the adsorbent, use adsorbent E, and otherwise, manufacture filter medium E in the same manner as in Example 1.

[0153] [Example 6](Adsorbent F)

[0154] (Inorganic porous body)

[0155] Use the same inorganic porous body as that used in Example 1 (adsorbent A).

[0156] (Amine compound)

[0157] Use ethylenethiourea (manufactured by Nacalai Tesque, Inc.).

[0158] (Sulfide compound)

[0159] Use the same sulfide compound as that used in Example 1 (adsorbent A).

[0160] (Preparation of adsorbent)

[0161] Dissolve 5% by mass of the above amine compound and 2% by mass of the above sulfide compound in water, mix the resulting aqueous solution with an inorganic porous body and dry it to prepare adsorbent F. The pH of adsorbent F when 5 g is dispersed in 100 g of water is 6.5.

[0162] (Manufacture of filter medium)

[0163] Use the same materials for the air-permeable sheet for the upstream side, the air-permeable sheet for the downstream side, and the hot-melt resin as those used in Example 1. As the adsorbent, use adsorbent F, and otherwise, manufacture filter medium F in the same manner as in Example 1.

[0164] [Comparative Example 1](Adsorbent G)

[0165] (Inorganic porous body)

[0166] Use the same product as adsorbent A.

[0167] (Amine compound)

[0168] Use the same amine compound as that used in Example 1 (adsorbent A).

[0169] (Substitute for thioether compound)

[0170] Instead of using a thioether compound, L-cysteine (manufactured by Tomochem Co., Ltd.) is used instead.

[0171] (Preparation of adsorbent)

[0172] Dissolve 5% by mass of the above amine compound and 2% by mass of L-cysteine in water, mix the resulting aqueous solution with an inorganic porous body and dry it to prepare adsorbent G. The pH of adsorbent G when 5 g is dispersed in 100 g of water is 6.5.

[0173] (Manufacture of filter medium)

[0174] The same materials as those used in Example 1 are used for the air-permeable sheet for the upstream side, the air-permeable sheet for the downstream side, and the hot-melt resin. As the adsorbent, adsorbent G is used, and except for this, the filter medium G is produced in the same manner as in Example 1.

[0175] [Comparative Example 2] (Adsorbent H)

[0176] (Inorganic porous body)

[0177] The same inorganic porous body as that used in Example 1 (adsorbent A) is used.

[0178] (Amine compound)

[0179] The same amine compound as that used in Example 1 (adsorbent A) is used.

[0180] (Substitute for thioether compound)

[0181] Instead of using a thioether compound, L-α-alanine (manufactured by Nacalai Tesque, Inc.) is used instead.

[0182] (Preparation of adsorbent)

[0183] Dissolve 5% by mass of the above amine compound and 2% by mass of L-α-alanine in water, mix the resulting aqueous solution with an inorganic porous body and dry it to prepare adsorbent H. The pH of adsorbent H when 5 g is dispersed in 100 g of water is 6.4.

[0184] (Manufacture of filter medium)

[0185] The same materials as those used in Example 1 are used for the air-permeable sheet for the upstream side, the air-permeable sheet for the downstream side, and the hot-melt resin. As the adsorbent, adsorbent H is used, and except for this, the filter medium H is produced in the same manner as in Example 1.

[0186] [Comparative Example 3] (Adsorbent I)

[0187] (Inorganic porous material)

[0188] The same inorganic porous material as that used in Example 1 (Adsorbent A) is used.

[0189] (Amine compound)

[0190] The same amine compound as that used in Example 1 (Adsorbent A) is used.

[0191] (Substitute for sulfide compound)

[0192] The sulfide compound is not used, and succinic anhydride (manufactured by Nacalai Tesque, Inc.) is used instead.

[0193] (Preparation of adsorbent)

[0194] 5% by mass of the above amine compound and 2% by mass of succinic anhydride are dissolved in water, and the resulting aqueous solution is mixed with the inorganic porous material and dried to prepare Adsorbent I. The pH of Adsorbent I when 5 g is dispersed in 100 g of water is 6.5.

[0195] (Manufacture of filter medium)

[0196] The same materials as those used in Example 1 are used for the air-permeable sheet for the upstream side, the air-permeable sheet for the downstream side, and the heat-sealing resin. As the adsorbent, Adsorbent I is used, and a filter medium I is produced in the same manner as in Example 1 except for this.

[0197] [Comparative Example 4] (Adsorbent J)

[0198] (Inorganic porous material)

[0199] The same inorganic porous material as that used in Example 1 (Adsorbent A) is used.

[0200] (Amine compound)

[0201] The same amine compound as that used in Example 1 (Adsorbent A) is used.

[0202] (Use or non-use of sulfide compound)

[0203] The sulfide compound is not used.

[0204] (Preparation of adsorbent)

[0205] 5% by mass of the above amine compound is dissolved in water, and the resulting aqueous solution is mixed with the inorganic porous material and dried to prepare Adsorbent J. The pH of Adsorbent J when 5 g is dispersed in 100 g of water is 6.5.

[0206] (Manufacture of filter medium)

[0207] For the air-permeable sheet for the upstream side, the air-permeable sheet for the downstream side, the hot-melt resin uses the same substance as that used in Example 1, and as the adsorbent, Adsorbent J is used. Except for this, the filter medium J is produced in the same manner as in Example 1.

[0208]

[0209] <Summary>

[0210] The acetaldehyde removal efficiency, adsorption capacity, and reduction rate of the adsorption capacity of Examples 1 to 6 and Comparative Examples 1 to 4 are shown in Table 1.

[0211] In Examples 1 to 6, a thioether compound is used in combination with an amine compound. Therefore, the initial removal efficiency of acetaldehyde just after the sample is produced all satisfies 40% or more, and compared with Comparative Examples 1 to 4, the reduction rate of the adsorption capacity after the deterioration test over time also satisfies 50% or less.

[0212] In Examples 1, 2, 4, and 5, hydrazides are used as the amine compound, and compared with Examples 3 and 6, a high value is shown for the adsorption capacity of acetaldehyde just after the sample is produced.

[0213] Furthermore, in Examples 1 and 2, adipic dihydrazide is used as the amine compound, and compared with Examples 3 to 6, a particularly high value of 50% or more is shown for the adsorption capacity of acetaldehyde just after the sample is produced. 2 As described above, a particularly high value of 50% or more is shown for the initial removal efficiency.

[0214] Furthermore, in Examples 1, 3 to 6, L-methionine is used as the thioether compound, and compared with Example 2, a low value of 50% or less is shown for the reduction rate of the adsorption capacity after the heat resistance test.

[0215] Industrial Applicability

[0216] The filter medium using the adsorbent of the present invention is preferably used as an air filter for purifying the air in the passenger compartments of automobiles, railway vehicles, etc., an air purifier filter for use in healthy houses, pet-friendly apartments, elderly care facilities, hospitals, offices, etc., an air conditioner filter, an intake and exhaust filter for OA equipment, a building air conditioner filter, and an air filter medium for industrial clean rooms.

Claims

1. Filter medium, characterized in that, An adsorbent is used, which is loaded with at least an amine compound and a compound having a thioether group in a functional group on an inorganic porous body. The adsorbent is sandwiched by a breathable sheet. The amine compound is a hydrazide. The compound having a thioether group in the functional group is one or more selected from L-methionine, D-methionine, D,L-methionine and their salts, and esters and amides of carboxyl groups contained in these methionines, dimethyl sulfide or diethyl sulfide. The loading amount of the amine compound is 0.5 parts by mass or more and 30 parts by mass or less with respect to 100 parts by mass of the inorganic porous body. The loading amount of the compound having a thioether group is 0.5 parts by mass or more and 20 parts by mass or less with respect to 100 parts by mass of the inorganic porous body.

2. The filter medium according to claim 1, wherein, The compound having a thioether group in the functional group is methionine.

3. The filter medium according to claim 1 or 2, wherein The pH of the adsorbent when 5 g is dispersed in 100 g of water is 3.0 or more and 7.5 or less.

4. The filter medium according to claim 1 or 2, wherein The adsorbent is further loaded with at least one acid selected from other organic acids and inorganic acids on the inorganic porous body.

5. The filter medium according to claim 1 or 2, wherein, The inorganic porous body is porous silica.

6. The filter medium according to claim 1 or 2, wherein, The adsorbent is fixed to the sheet by a thermoplastic resin.

7. Method for manufacturing filter medium, characterized in that, A compound having a thioether group in a functional group and an amine compound are dissolved in water, and the resulting solution is loaded on an inorganic porous body and dried. The amine compound is a hydrazide. The compound having a thioether group in the functional group is one or more selected from L-methionine, D-methionine, D,L-methionine and their salts, and esters and amides of carboxyl groups contained in these methionines, dimethyl sulfide or diethyl sulfide.

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