Adsorbent and its manufacturing method, filter medium and air filter

Abstract

The present invention addresses the problem of providing an adhesive agent, a filtration material, and an air filter that have exceptional aldehyde removal performance and that undergo little deterioration over time.　The present invention is an adhesive agent characterized in that at least an amine-based compound and a compound having sulfide groups as functional groups are carried on an inorganic porous body.

Description

[Technical Field]

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

[0002] The growing trend toward health and comfort has led to a growing need for improved living environments. There are a wide variety of pollutants in indoor air, but aldehydes, such as acetaldehyde, are particularly problematic as pollutants. Acetaldehyde is a typical odorous component found in cigarette smoke and automobile exhaust fumes, and its odor threshold is low, making it easily noticeable even at low concentrations.

[0003] Conventionally, activated carbon with a large surface area and pore volume has been used to remove malodorous components from the air. However, the equilibrium adsorption amount of lower aliphatic aldehydes on activated carbon is significantly smaller than that of other malodorous components, and therefore it is not suitable for practical use.

[0004] As a technique for removing lower aliphatic aldehydes, a method has been proposed in which activated carbon is impregnated with an amine compound to improve its performance (see Patent Document 1).

[0005] On the other hand, with conventional adsorbents, these amine compounds are easily oxidized by oxygen in the air, which reduces the effectiveness of their chemical adsorption action on aldehydes, making it impossible to maintain aldehyde removal performance for a long period of time.

[0006] To solve this problem, a technology has been proposed in which silica gel is impregnated with an acid hydrazide compound, which is an amine compound, and a compound having a thiol group as a functional group as an antioxidant, thereby suppressing the oxidation of the amine compound and suppressing the deterioration of aldehyde removal performance over time (see Patent Document 2). [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Application Publication No. 5-317703 [Patent Document 2] International Publication No. 2015 / 037483 Summary of the Invention [Problem to be solved by the invention]

[0008] However, although the adsorbent in which a compound having a thiol group as a functional group is impregnated onto silica gel has been confirmed to have the ability to suppress deterioration over time, further improvement in performance has been desired. Therefore, 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. [Means for solving the problem]

[0009] The present invention is an adsorbent characterized in that at least an amine compound and a compound having a sulfide group as a functional group are supported on an inorganic porous material.

[0010] The present invention also relates to a filter medium characterized by using the adsorbent of the present invention.

[0011] The present invention also relates to an air filter comprising the filter medium of the present invention.

[0012] The present invention also provides a method for producing an adsorbent, which comprises dissolving a compound having a sulfide group as a functional group and an amine compound in water, impregnating the resulting solution with an inorganic porous material, and drying the resulting solution. [Effects of the Invention]

[0013] The present invention provides an adsorbent, a filter medium, and an air filter that have excellent aldehyde removal performance and little deterioration over time by impregnating an inorganic porous material with at least an amine compound and a compound having a sulfide group as a functional group. DETAILED DESCRIPTION OF THE INVENTION

[0014] The present invention will be described in detail below. In the present invention, the term "not less than" means that the value is equal to or greater than the indicated value. The term "not more than" means that the value is equal to or smaller than the indicated value.

[0015] The adsorbent of the present invention has an inorganic porous body. The use of the inorganic porous body provides a surface area that can come into contact with the treatment air, and allows a sufficient amount of the chemical agent described below to be supported, thereby increasing the efficiency of aldehyde removal.

[0016] The inorganic porous material used in the present invention is preferably selected from the group consisting of activated carbon, zeolite, activated alumina, silica gel, activated clay, aluminum silicate, and magnesium silicate. Two or more types selected from this group can also be used in combination.

[0017] Among inorganic porous materials, porous silica is advantageous in that it does not react with amine compounds (described later) and can suppress deterioration of the amine compounds supported on the porous silica. In addition, porous silica is highly hydrophilic and has a high affinity with water-soluble chemicals such as amine compounds, which can further improve the aldehyde adsorption performance of the adsorbent. Therefore, porous silica is preferred as the inorganic porous material.

[0018] Furthermore, the inorganic porous material used in the present invention is preferably particulate. Particulate materials can effectively achieve both performance and economic benefits. Fibrous inorganic porous materials have an increased specific surface area, which increases the contact efficiency with the target gas and improves performance (removal efficiency), but are expensive.

[0019] The average particle size of the inorganic porous material is preferably 1 μm or more and 1000 μm or less. The average particle size here refers to the mass-average particle size specified in JIS-K1474 (2014) Activated Carbon Test Method. By setting the average particle size of the inorganic porous material to 1000 μm or less, more preferably 600 μm or less, the adsorbent's adsorption rate of lower aliphatic aldehyde gases can be increased, and the material is easy to manufacture, has excellent strength, is resistant to breakage, and reduces the generation of dust due to breakage. On the other hand, by setting the average particle size to 50 μm or more, more preferably 100 μm or more, the inorganic porous material can be prevented from scattering, resulting in excellent handleability and processability.

[0020] The average pore diameter of the inorganic porous body in the present invention is preferably 4 nm or more and 50 nm or less. The average pore diameter in the present invention refers to the peak diameter obtained by the BJH method, and more specifically, is determined using an adsorption isotherm obtained by a nitrogen adsorption method at 77 Kelvin (liquid nitrogen temperature). By setting the average pore diameter of the inorganic porous body to 50 nm or less, more preferably 30 nm or less, it is possible to increase the specific surface area of ​​the inorganic porous body while suppressing a decrease in the mechanical strength of the inorganic porous body, thereby improving the adsorbent's ability to remove low-boiling aldehydes. Furthermore, by setting the average pore diameter of the inorganic porous body to 4 nm or more, more preferably 5 nm or more, it is possible to promote the penetration of amine compounds and VOC gases into the pores of the granular inorganic porous body.

[0021] The specific surface area of ​​the inorganic porous material used in the present invention is 30 m2 in terms of BET specific surface area. 2 / g or more 1000m 2 The specific surface area of ​​the inorganic porous material is preferably 30 m / g or less. 2 / g or more, more preferably 50m 2 / g or more, the effective area as a reaction field for the amine compound supported by the inorganic porous material is increased, and the reaction rate between the adsorbent and the VOC gas to be removed is improved. 2By setting the adsorption capacity to 1 / g or less, it is possible to suppress a decrease in handleability due to a decrease in the mechanical strength of the inorganic porous body, and also to suppress unintentional adsorption of VOC gases onto the adsorbent, which can lead to secondary odor generation.

[0022] It is important that the adsorbent of the present invention has an amine compound supported on an inorganic porous material, which can effectively adsorb aldehyde-based odorants.

[0023] Examples of such amine compounds that can be used include primary amine compounds having an amino group, such as aniline, acid hydrazides, benzylamine, naphthylamine, cyclohexylamine, (iso)propanolamine, ethanolamine, diethylenetriamine, triethylenetetramine, styrene ethylamine methacrylate, and styrene amine acrylate, as well as monomers, oligomers, polymers, and amino group-containing derivatives derived from these compounds.

[0024] Examples of amine compounds other than primary amine compounds, for example, secondary amine compounds, include secondary amine compounds of alkyl groups such as azoles, azines, dipropylamine, and dibutylamine, 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, and 3,5-di-n-butyl-1,2,4-triazole, as well as cyclic secondary amine compounds such as piperidine, piperazine, and pyrrolidine.

[0025] Furthermore, the secondary amine compound preferably has an amide bond or a urea bond in order to prevent the re-release of aldehydes. Among these, 1,3-dimethylurea and ethyleneurea are more preferred because they are highly safe, do not emit an amine odor, are water-soluble, and have good processability.

[0026] Examples of the tertiary amine compound include compounds such as vinylbenzyl dimethylamine, vinylbenzyl diethylamine, styrene diethylamine acrylate, styrene diethylamine methacrylate, styrene dimethylamine acrylate, styrene dimethylamine methacrylate, styrene ethyl dimethylamine methacrylate, styrene ethyl diethylamine acrylate, and triethylamine, as well as monomers, oligomers, polymers, and tertiary amine compounds derived from these compounds.

[0027] Of these, primary amine compounds having an amino group are preferred, and acid hydrazides are more preferred, because they provide the adsorbent with superior performance in inhibiting the desorption of high-boiling aldehydes.

[0028] Acid hydrazides are compounds with an acid hydrazide group represented by -CO-NHNH2, derived from a carboxylic acid and hydrazine. A nitrogen atom with an unshared electron pair is attached to the α-position of the hydrazide terminal, significantly enhancing nucleophilic reactivity. This unshared electron pair nucleophilically attacks the carbonyl carbon atom of an aldehyde compound, immobilizing the aldehyde compound as a hydrazine derivative, which is thought to be capable of exhibiting adsorption performance for the aldehyde compound.

[0029] Among aldehyde compounds, acetaldehyde has an electron-donating alkyl group at the α-position of the carbonyl carbon, which makes the carbonyl carbon less electrophilic and difficult to chemisorb. However, the acid hydrazides preferably employed in the adsorbents used in the present invention have high nucleophilic reactivity as described above, and therefore exhibit good chemisorption performance even for acetaldehyde.

[0030] In addition, the acid hydrazides are preferably water-soluble acid hydrazides from the viewpoint of ease of processing for supporting them on inorganic porous materials.

[0031] Here, the water-soluble acid hydrazides refer to acid hydrazides that dissolve in water (25° C.) in an amount of 0.5% by mass or more.

[0032] Examples of the acid hydrazide compound used in the present invention include acid monohydrazides having one acid hydrazide group in the molecule, such as formhydrazide, acetohydrazide, propionic acid hydrazide, and benzoic acid hydrazide; acid dihydrazides having two acid hydrazide groups in the molecule, such as carbodihydrazide, glutamic acid dihydrazide, succinic acid dihydrazide, adipic acid dihydrazide, dodecanedioic acid dihydrazide, fumaric acid dihydrazide, maleic acid dihydrazide, and terephthalic acid dihydrazide; and acid polyhydrazides having three or more acid hydrazide groups in the molecule, such as polyacrylic acid hydrazide.

[0033] Among these, carbodihydrazide, succinic acid dihydrazide, and adipic acid dihydrazide are preferably used from the viewpoint of adsorption performance. Furthermore, the use of adipic acid dihydrazide exhibits an excellent effect, particularly in terms of the adsorption capacity of acetaldehyde.

[0034] The amount of the amine compound supported is preferably 0.5 parts by mass or more and 30 parts by mass or less per 100 parts by mass of the inorganic porous material. By setting the amount of the amine compound to 0.5 parts by mass or more, more preferably 2.0 parts by mass or more, it is possible to effectively improve the aldehyde removal efficiency and aldehyde adsorption capacity. On the other hand, by setting the amount of the amine compound supported to 30 parts by mass or less, more preferably 20 parts by mass or less, it is possible to prevent the amine compound from crystallizing and blocking the pores of the inorganic porous material, which can reduce the adsorption rate and cause powder shedding.

[0035] Furthermore, it is important that the adsorbent of the present invention also has a compound having a sulfide group (—S—) as a functional group (hereinafter also referred to as a “sulfide compound”) supported on the inorganic porous material. This makes it possible to obtain an adsorbent in which deterioration of aldehyde removal performance over time is suppressed. The presence of metal on the pore surface of the inorganic porous material, and the catalytic action of this metal promotes the decomposition reaction of amine compounds, which is thought to be the main cause of deterioration of aldehyde removal performance over time. This tendency is particularly pronounced when the amine compound is an acid hydrazide compound. In contrast, sulfide groups are reactive with metals, which is thought to be able to suppress the decomposition reaction described above. Furthermore, since sulfide groups themselves are easily oxidized, supporting a sulfide compound is thought to have the effect of preventing oxidative decomposition of amine compounds, which have excellent reactivity with aldehydes.

[0036] Examples of sulfide compounds used in the present invention include dimethyl sulfide, diethyl sulfide, and methionines. Specific examples of methionines include one or more selected from L-methionine, D-methionine, D,L-methionine, and salts thereof, as well as methionine derivatives such as esters of the carboxyl group contained in these methionines and amides of the carboxyl group. Among these, methionine is preferred because it is inexpensive and has excellent heat resistance. Among these, L-methionine is preferred because it is abundant in nature and inexpensive.

[0037] The amount of the sulfide compound supported is preferably 0.5 parts by mass or more and 20 parts by mass or less per 100 parts by mass of the inorganic porous material. By setting the amount of the sulfide compound to 0.5 parts by mass or more, more preferably 1.0 part by mass or more, it is possible to sufficiently react with the metal components attached to the pore surfaces. On the other hand, by setting the amount to 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 material from being blocked, which would lead to a decrease in the adsorption rate.

[0038] Examples of a method for supporting the amine compound and the sulfide compound on the inorganic porous material include a method in which the amine compound and the sulfide compound are dissolved in water, the obtained aqueous solution is impregnated onto the inorganic porous material, and then the inorganic porous material is dried.

[0039] The gas adsorbent of the present invention preferably has a pH (hydrogen ion exponent) of 3.0 or more and 7.5 or less when 5 g is dispersed in 100 g of water at 25°C. This improves the ability to remove aldehydes. By adjusting the pH of the aqueous solution to 7.5 or less, more preferably 6.5 or less, the intermediate produced from the reaction in which the lone electron pair of the amine compound nucleophilically attacks the carbonyl carbon atom of the aldehyde is easily protonated and dehydrated in the acidic reaction field, allowing the immobilization reaction to a derivative to proceed sufficiently. Furthermore, by adjusting the pH of the aqueous solution to 3.0 or more, more preferably 4.0 or more, the activity of the lone electron pair of the amine compound to nucleophilically attack the carbonyl carbon atom of the aldehyde can be sufficiently maintained.

[0040] The pH of the adsorbent can be adjusted by supporting at least one acid selected from the group consisting of organic acids and inorganic acids (hereinafter also referred to as "organic / inorganic acid") on the adsorbent. The organic / inorganic acid is preferably an acid that does not generate an odor by itself.

[0041] Specific examples of organic acids include adipic acid, succinic anhydride, sulfanilic acid, malic acid, citric acid, amino acids, etc. When an inorganic porous body is impregnated with an aqueous dispersion of adipic acid dihydrazide as an amine compound, adipic acid is preferably used. Adipic acid is preferably used because it stably maintains the balance of the adipic acid dihydrazide dispersion and does not generate odor or exhibit hygroscopicity.

[0042] As the inorganic acid, phosphoric acid is preferably used because it can form a hardly soluble salt with dissolved heavy metals such as iron, which promotes the oxidation of sulfide groups, thereby insolubilizing the heavy metals.

[0043] As a method for supporting an organic / inorganic acid on an adsorbent, when an amine compound and a sulfide compound are impregnated as an aqueous dispersion, it is preferable to add the organic / inorganic acid by mixing it with this aqueous dispersion.

[0044] Next, the filter medium of the present invention is characterized by using the adsorbent of the present invention.

[0045] The filter medium of the present invention is preferably formed by sandwiching the adsorbent of the present invention between breathable sheet-like materials (hereinafter also referred to as "breathable sheet-like materials").

[0046] The breathable sheet material is preferably a fiber structure, specifically, cotton-like material, knitted or woven fabric, nonwoven fabric, paper, and other three-dimensional net-like materials. Laminates of these materials can also be used. By adopting such a structure, it is possible to increase the surface area while ensuring breathability. From the viewpoint of use as an air filter, nonwoven fabric is preferably used.

[0047] Fibers that form the breathable sheet-like material include natural fibers, synthetic fibers, and inorganic fibers such as glass fibers and metal fibers, and among these, synthetic fibers made of melt-spinnable thermoplastic resins are preferred. Examples of thermoplastic resins that form the synthetic fibers include polyester, polyamide, polyolefin, acrylic, vinylon (polyvinyl alcohol), polystyrene, polyvinyl chloride, polyvinylidene chloride, and polylactic acid, and can be selected depending on the application. Multiple types can also be used in combination.

[0048] The fiber diameter of the fibers constituting the breathable sheet material can be selected depending on the target breathability and dust collection performance when used as an air filter, but is preferably 1 μm or more and 2000 μm or less. By setting the fiber diameter to 1 μm or more, more preferably 5 μm or more, clogging of the adsorbent on the surface of the fiber structure can be prevented, preventing a decrease in breathability. Furthermore, by setting the fiber diameter to 2000 μm or less, more preferably 100 μm or less, a decrease in the adsorbent carrying capacity and a decrease in contact efficiency with the treated air due to a decrease in the fiber surface area can be prevented.

[0049] The basis weight of the breathable sheet material is 10 g / m 2 More than 500g / m 2 It is preferable that the basis weight is 10 g / m or less. 2 By setting the weight to 500g / m or more, sufficient strength to withstand the processing required to support the adsorbent can be obtained, and the rigidity required to maintain the filter structure when air is passed through can be obtained. 2 or less, more preferably 200 g / m 2 By satisfying the following conditions, the adsorbent can be uniformly supported even inside the breathable sheet-like material, and the handling is also excellent when secondary processing into a pleated or honeycomb shape.

[0050] At least one of the breathable sheets is preferably electret-treated, which allows it to capture submicron-sized or nano-sized fine dust particles that are normally difficult to remove by electrostatic force.

[0051] As materials for constituting such electret-treated breathable sheet-like materials, materials having high electrical resistivity such as polyolefin resins such as polypropylene, polyethylene, polystyrene, polybutylene terephthalate and polytetrafluoroethylene, aromatic polyester resins such as polyethylene terephthalate, and polycarbonate resins are preferably used.

[0052] In the filter material of the present invention, the adsorbent is preferably fixed to the breathable sheet material by a thermoplastic resin.By using the thermoplastic resin as a binder resin, the adsorbent can be firmly fixed to the breathable sheet material while preventing the adsorbent from being covered by the binder and its function from being reduced.

[0053] As the thermoplastic resin for immobilizing the adsorbent of the present invention on the breathable sheet material, thermoplastic resins such as EVA, polyester, polyamide and low density polyethylene can be used.

[0054] A preferred method for immobilizing the adsorbent on a breathable sheet is to spread a mixed powder of the adsorbent of the present invention and a thermoplastic resin on the breathable sheet, and then overlay another breathable sheet on top of it and heat press them to integrate them. By adopting this method, it is possible to prevent the surface of the adsorbent of the present invention from being covered with the thermoplastic resin, which would otherwise cause a decrease in functionality, and it is advantageous in terms of adsorption speed, allowing the adsorption capacity to be expressed extremely effectively.

[0055] The amount of adsorbent carried in the filter medium of the present invention is 5 g / m 2 More than 300g / m 2 The loading amount is preferably 5 g / m or less. 2 More preferably, 10 g / m 2 By setting the loading amount to 300 g / m or more, it is possible to effectively improve the removal efficiency of aldehydes and the adsorption capacity. 2 or less, more preferably 200 g / m 2 By setting the following, clogging of the adsorbent on the surface of the breathable adsorbent sheet can be prevented, and a decrease in breathability can be suppressed.

[0056] In addition, the filter material 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 it is possible to adsorb and remove all VOC gases.

[0057] The air filter of the present invention is characterized by using the filter medium of the present invention.

[0058] The filter may be flat, but a pleated or honeycomb shape is preferred. The pleated shape increases the contact area with the processing air when used as a cross-flow filter, and the honeycomb shape increases the collection efficiency when used as a parallel-flow filter, while simultaneously reducing pressure loss.

[0059] In addition, the air filter of the present invention is preferably configured such that the filter medium of the present invention is housed in a frame, from the viewpoint of air treatment efficiency and ease of handling. [Example]

[0060] [Measurement method] (1) pH (hydrogen ion exponent) of the adsorbent 5 g of adsorbent was immersed in 100 g of pure water at 25°C, gently stirred, and then left to stand for 10 minutes. The pH of the resulting aqueous solution was measured using a pH meter (Lacombe Ecoscan pH 5). The measurement was carried out three times, and the average value was used.

[0061] (2) Method for supporting amine compounds and sulfide compounds The inorganic porous material was impregnated with an aqueous solution of a mixed amine compound and a sulfide compound, and then dried to prepare the polymer.

[0062] (3) Adsorbent and thermoplastic resin loading (g / m 2 ) The adsorbent and thermoplastic resin were mixed and stirred to form a powder mixture, which was then spread onto a breathable sheet material. Another breathable sheet material was then placed on top of the mixture and heat-pressed to combine them, and the total basis weight was measured. The basis weights of the two breathable sheets were subtracted from the total basis weight, and the result was multiplied by the ratio of the amounts of each component added to determine the amount of adsorbent and thermoplastic resin supported on the entire filter medium.

[0063] (4) Acetaldehyde removal performance A 12cm x 12cm flat filter medium was attached to a 10cm x 10cm experimental duct, and air at a temperature of 23°C and a humidity of 50% was blown into the duct at a speed of 0.2m / sec. Acetaldehyde (also written as C2H4O) was added from a standard gas cylinder from the upstream side to an upstream concentration of 10ppm. Air samples were taken upstream and downstream of the filter medium, and the acetaldehyde concentration was measured over time using an infrared absorption continuous monitor. The removal efficiency was calculated using the following formula. Removal efficiency (%) = [(C0-C) / C0] x 100 Here, C0: Upstream acetaldehyde concentration (10 ppm) C: Downstream acetaldehyde concentration (ppm) The removal efficiency 100 seconds after the start of acetaldehyde addition was defined as the initial removal efficiency. If the initial acetaldehyde removal efficiency immediately after sample preparation was 40% or higher, the sample was deemed to have passed.

[0064] In addition, the removal efficiency after 100 seconds was measured over time, and the total amount of adsorption (the mass increase (g) of the flat filter material) until the removal efficiency decreased to 5% was divided by the duct area (10 cm x 10 cm) to obtain a value of 1 m 2 The adsorption capacity per unit mass is calculated as g / m 2 ) was evaluated.

[0065] (5) Aging test The flat gas adsorption sheet was left to stand for 3 days after sample preparation in an environment set at a temperature of 85°C and a humidity of 85%RH, and then attached to an experimental duct, and its acetaldehyde removal performance was evaluated using the method described in (4) above.

[0066] The rate of decrease in adsorption capacity due to the deterioration test over time was calculated using the following formula. Decrease rate of adsorption capacity (%) = [((adsorption capacity immediately after sample preparation) - (adsorption capacity after aging test))) / (adsorption capacity immediately after sample preparation)] × 100 If the rate of decrease in adsorption capacity due to the deterioration test over time was 50% or less, the sample was evaluated as passing.

[0067] (6) Heat resistance test The flat gas adsorption sheet was left to stand for one day after sample preparation in an environment set at a temperature of 120°C and a humidity of 25%RH, and then attached to an experimental duct, and its acetaldehyde removal performance was evaluated using the method described in (4) above.

[0068] The rate of decrease in adsorption capacity due to the heat resistance test was calculated using the following formula. Decrease rate of adsorption capacity (%) = [((adsorption capacity immediately after sample preparation) - (adsorption capacity after heat resistance test))) / (adsorption capacity immediately after sample preparation)] × 100 If the rate of decrease in adsorption capacity in the heat resistance test was 50% or less, it was evaluated as "excellent."

[0069] [Example 1] (Adsorbent A) (inorganic porous material) As the inorganic porous material, porous silica (Fuji Silysia Chemical Ltd.) with an average particle size of 300 μm was used.

[0070] (amine compounds) Adipic acid dihydrazide (Otsuka Chemical Co., Ltd.) was used.

[0071] (sulfide compounds) L-methionine (manufactured by Wakenyaku Co., Ltd.) was used.

[0072] (Preparation of Adsorbent) An aqueous solution prepared by dissolving 5% by mass of the amine compound and 2% by mass of the sulfide compound in water was mixed with an inorganic porous material and dried to prepare adsorbent A. When 5 g of adsorbent A was dispersed in 100 g of water, the pH was 6.3.

[0073] (Breathable sheet material for upstream side) The breathable sheet-like material positioned upstream of the air flow is made of 16.5 mass% vinylon (polyvinyl alcohol) fiber with a single fiber fineness of 1.5 dtex, 22 mass% vinylon (polyvinyl alcohol) fiber with a single fiber fineness of 7.1 dtex, 16.5 mass% polyethylene terephthalate fiber with a single fiber fineness of 2.0 dtex, and 45 mass% acrylic resin binder containing a phosphorus-based flame retardant, and has a basis weight of 50 g / m. 2 Chemical bonded nonwoven fabric was used.

[0074] (Downstream breathable sheet material) The breathable sheet material positioned downstream of the air flow is made of polypropylene fiber electret-processed melt-blown nonwoven fabric with a basis weight of 20 g / m. 2 An electrostatically charged fiber sheet was used.

[0075] (thermal adhesive resin) Low-density polyethylene (manufactured by Tokyo Ink Co., Ltd., melting point 98 to 104°C) was used.

[0076] (Production of filter media) The adsorbent and the heat-sealing resin were mixed in a mass ratio of 2:1 and stirred until homogeneous. The mixture was then spread on a downstream breathable sheet, which was then covered with an upstream breathable sheet and heat-pressed to produce filter medium A.

[0077] [Example 2] (Adsorbent B) (inorganic porous material) The same adsorbent as that used in Example 1 (adsorbent A) was used.

[0078] (amine compounds) The same adsorbent as that used in Example 1 (adsorbent A) was used.

[0079] (sulfide compounds) Diethyl sulfide (manufactured by Tokyo Chemical Industry Co., Ltd.) was used.

[0080] (Preparation of Adsorbent) An aqueous solution prepared by dissolving 5% by mass of the amine compound and 2% by mass of the sulfide compound in water was mixed with an inorganic porous material and dried to prepare adsorbent B. When 5 g of adsorbent B was dispersed in 100 g of water, the pH was 6.4. (Production of filter media) The upstream breathable sheet material, the downstream breathable sheet material, and the heat-sealing resin were the same as those used in Example 1, and filter medium B was prepared in the same manner as in Example 1, except that adsorbent B was used as the adsorbent.

[0081] [Example 3] (Adsorbent C) (inorganic porous material) The same adsorbent as that used in Example 1 (adsorbent A) was used.

[0082] (amine compounds) 1,3-Dimethylurea (Nacalai Tesque) was used.

[0083] (sulfide compounds) The same adsorbent as that used in Example 1 (adsorbent A) was used.

[0084] (Preparation of Adsorbent) An aqueous solution prepared by dissolving 5% by mass of the amine compound and 2% by mass of the sulfide compound in water was mixed with an inorganic porous material and dried to prepare adsorbent C. When 5 g of adsorbent C was dispersed in 100 g of water, the pH was 6.4.

[0085] (Production of filter media) The upstream breathable sheet material, the downstream breathable sheet material, and the heat-sealing resin were the same as those used in Example 1, and filter material C was prepared in the same manner as in Example 1, except that adsorbent C was used as the adsorbent.

[0086] [Example 4] (Adsorbent D) (inorganic porous material) The same adsorbent as that used in Example 1 (adsorbent A) was used.

[0087] (amine compounds) Carbodihydrazide (manufactured by Nippon Finechem Co., Ltd.) was used.

[0088] (sulfide compounds) The same adsorbent as that used in Example 1 (adsorbent A) was used.

[0089] (Preparation of Adsorbent) An aqueous solution prepared by dissolving 5% by mass of the amine compound and 2% by mass of the sulfide compound in water was mixed with an inorganic porous material and dried to prepare adsorbent D. When 5 g of adsorbent D was dispersed in 100 g of water, the pH was 6.5.

[0090] (Production of filter media) Filter material D was prepared in the same manner as in Example 1, except that the upstream breathable sheet material, downstream breathable sheet material, and heat-sealing resin were the same as those used in Example 1, and adsorbent D was used as the adsorbent.

[0091] [Example 5] (Adsorbent E) (inorganic porous material) The same adsorbent as that used in Example 1 (adsorbent A) was used.

[0092] (amine compounds) Succinic acid dihydrazide (manufactured by Nippon Finechem Co., Ltd.) was used.

[0093] (sulfide compounds) The same adsorbent as that used in Example 1 (adsorbent A) was used.

[0094] (Preparation of Adsorbent) An aqueous solution prepared by dissolving 5% by mass of the amine compound and 2% by mass of the sulfide compound in water was mixed with an inorganic porous material and dried to prepare adsorbent E. When 5 g of adsorbent E was dispersed in 100 g of water, the pH was 6.4.

[0095] (Production of filter media) Filter medium E was prepared in the same manner as in Example 1, except that the upstream breathable sheet material, downstream breathable sheet material, and heat-sealing resin were the same as those used in Example 1, and adsorbent E was used as the adsorbent.

[0096] [Example 6] (Adsorbent F) (inorganic porous material) The same adsorbent as that used in Example 1 (adsorbent A) was used.

[0097] (amine compounds) Ethylene urea (manufactured by Nacalai Tesque) was used.

[0098] (sulfide compounds) The same adsorbent as that used in Example 1 (adsorbent A) was used.

[0099] (Preparation of Adsorbent) An aqueous solution prepared by dissolving 5% by mass of the amine compound and 2% by mass of the sulfide compound in water was mixed with an inorganic porous material and dried to prepare adsorbent F. When 5 g of adsorbent F was dispersed in 100 g of water, the pH was 6.5.

[0100] (Production of filter media) The upstream breathable sheet material, the downstream breathable sheet material, and the heat-sealing resin were the same as those used in Example 1, and filter medium F was prepared in the same manner as in Example 1, except that adsorbent F was used as the adsorbent.

[0101] [Comparative Example 1] (Adsorbent G) (inorganic porous material) The same product as adsorbent A was used.

[0102] (amine compounds) The same adsorbent as that used in Example 1 (adsorbent A) was used.

[0103] (Substitute for sulfide compounds) No sulfide compound was used, but instead L-cysteine ​​(manufactured by Tomo Chemical Co., Ltd.) was used.

[0104] (Preparation of Adsorbent) An aqueous solution of 5% by mass of the amine compound and 2% by mass of L-cysteine ​​dissolved in water was mixed with an inorganic porous material and dried to prepare adsorbent G. When 5 g of adsorbent G was dispersed in 100 g of water, the pH was 6.5.

[0105] (Production of filter media) The upstream breathable sheet material, the downstream breathable sheet material, and the heat-sealing resin were the same as those used in Example 1, and filter medium G was prepared in the same manner as in Example 1, except that adsorbent G was used as the adsorbent.

[0106] [Comparative Example 2] (Adsorbent H) (inorganic porous material) The same adsorbent as that used in Example 1 (adsorbent A) was used.

[0107] (amine compounds) The same adsorbent as that used in Example 1 (adsorbent A) was used.

[0108] (Substitute for sulfide compounds) No sulfide compound was used, but instead L-α-alanine (manufactured by Nacalai Tesque) was used.

[0109] (Preparation of Adsorbent) An aqueous solution of 5% by mass of the above amine compound and 2% by mass of L-α-alanine dissolved in water was mixed with an inorganic porous material and dried to prepare adsorbent H. When 5 g of adsorbent H was dispersed in 100 g of water, the pH was 6.4.

[0110] (Production of filter media) The upstream breathable sheet material, the downstream breathable sheet material, and the heat-sealing resin were the same as those used in Example 1, and filter material H was prepared in the same manner as in Example 1, except that adsorbent H was used as the adsorbent.

[0111] [Comparative Example 3] (Adsorbent I) (inorganic porous material) The same adsorbent as that used in Example 1 (adsorbent A) was used.

[0112] (amine compounds) The same adsorbent as that used in Example 1 (adsorbent A) was used.

[0113] (Substitute for sulfide compounds) No sulfide compound was used, but instead succinic anhydride (manufactured by Nacalai Tesque) was used.

[0114] (Preparation of Adsorbent) An aqueous solution of 5% by mass of the amine compound and 2% by mass of succinic anhydride was mixed with an inorganic porous material and dried to prepare adsorbent I. When 5 g of adsorbent I was dispersed in 100 g of water, the pH was 6.5.

[0115] (Production of filter media) The upstream breathable sheet material, the downstream breathable sheet material, and the heat-sealing resin were the same as those used in Example 1, and filter medium I was prepared in the same manner as in Example 1, except that adsorbent I was used as the adsorbent.

[0116] [Comparative Example 4] (Adsorbent J) (inorganic porous material) The same adsorbent as that used in Example 1 (adsorbent A) was used.

[0117] (amine compounds) The same adsorbent as that used in Example 1 (adsorbent A) was used.

[0118] (Whether or not sulfide compounds are used) No sulfide compounds were used.

[0119] (Preparation of Adsorbent) An aqueous solution in which 5% by mass of the above amine compound was dissolved in water was mixed with an inorganic porous material and dried to prepare adsorbent J. When 5 g of adsorbent J was dispersed in 100 g of water, the pH was 6.5.

[0120] (Production of filter media) The upstream breathable sheet material, the downstream breathable sheet material, and the heat-sealing resin were the same as those used in Example 1, and filter material J was prepared in the same manner as in Example 1, except that adsorbent J was used as the adsorbent.

[0121] [Table 1]

[0122] <Summary> Table 1 shows the acetaldehyde removal efficiency, adsorption capacity, and rate of decrease in adsorption capacity for Examples 1 to 6 and Comparative Examples 1 to 4.

[0123] In Examples 1 to 6, since a sulfide compound was used in combination with an amine compound, the initial acetaldehyde removal efficiency immediately after sample preparation was 40% or more, and the rate of decrease in adsorption capacity after a time-deterioration test was 50% or less compared to Comparative Examples 1 to 4.

[0124] In Examples 1, 2, 4 and 5, acid hydrazides were used as the amine compounds, and therefore all of them showed higher values ​​for the acetaldehyde adsorption capacity immediately after sample preparation compared with Examples 3 and 6.

[0125] Furthermore, in Examples 1 and 2, adipic acid dihydrazide was used as the amine compound, and therefore, in both cases, the adsorption capacity of acetaldehyde immediately after sample preparation was 0.30 g / m compared with Examples 3 to 6. 2 As mentioned above, the initial removal efficiency was particularly high at over 50%.

[0126] Furthermore, since Examples 1, 3 to 6 use L-methionine as the sulfide compound, all of them showed a low value of 50% or less in terms of the rate of decrease in adsorption capacity after the heat resistance test compared to Example 2. [Industrial Applicability]

[0127] The filter media using the adsorbent according to the present invention are preferably used as air filter media for purifying the air inside automobiles, railway vehicles, etc., filters for air purifiers used in healthy homes, pet-friendly apartments, elderly care facilities, hospitals, offices, etc., air conditioner filters, intake and exhaust filters for office automation equipment, filters for building air conditioning, and filters for industrial clean rooms.

Claims

1. An adsorbent comprising an inorganic porous material carrying at least an amine compound and a compound having a sulfide group as a functional group.

2. 2. The adsorbent according to claim 1, wherein the amine compound is an acid hydrazide.

3. 3. The adsorbent according to claim 1, wherein the compound having a sulfide group as a functional group is methionine.

4. The adsorbent according to any one of claims 1 to 3, wherein the pH when 5 g of the adsorbent is dispersed in 100 g of water is 3.0 or more and 7.5 or less.

5. 5. The adsorbent according to claim 1, wherein the inorganic porous material further supports at least one acid selected from the group consisting of other organic acids and inorganic acids.

6. The adsorbent according to any one of claims 1 to 5, wherein the inorganic porous material is porous silica.

7. A filter medium comprising the adsorbent according to any one of claims 1 to 6.

8. 8. The filter medium according to claim 7, wherein the adsorbent is sandwiched between breathable sheet-like materials.

9. 9. The filter medium according to claim 7, wherein the adsorbent is fixed to the sheet-like material by a thermoplastic resin.

10. An air filter comprising the filter material according to any one of claims 7 to 9.

11. A method for producing an adsorbent, comprising dissolving a compound having a sulfide group as a functional group and an amine compound in water, impregnating the resulting solution with an inorganic porous material, and drying the material.

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