gas adsorbent

Abstract

The objective is to provide a filter material for air filters that has high siloxane removal performance and also has an effect of suppressing secondary odor generation. [Solution] Based on GCMC analysis, V1 is the pore volume of pores with a diameter of 0.4 nm or more and less than 1 nm, and V2 is the pore volume of pores with a diameter of 1 nm or more and 2 nm or less. If V1 / (V1+V2) is 0.55 or more, the specific surface area is 900-1200 m². 2 Activated carbon A and V2 / (V1+V2) at a ratio of 0.55 or higher, with a specific surface area of ​​1500-3000 m². 2 Use a gas adsorbent containing activated carbon B at a concentration of / g and having an average particle size of 100 to 900 μm.

Description

[Technical Field]

[0001] This invention relates to a gas adsorbent that has excellent siloxane gas removal performance and a secondary odor suppression effect. [Background technology]

[0002] Atmospheric pollutants are diverse, including organic gases such as benzene, toluene, butane, and siloxane gas, as well as polar gases such as hydrogen sulfide, ammonia, aldehydes, and acetic acid. Gas adsorbents are needed that offer high removal performance for these gases and prevent the re-release of gases that have been adsorbed and retained.

[0003] Among the gas species for which adsorption is needed, siloxane gas is known to cause various problems. For example, in waste treatment processes, siloxane gas contained in digester gas generated from waste and sludge after sewage treatment is known to adhere to engines and turbines, significantly reducing their durability (see, for example, Patent Document 1).

[0004] Furthermore, in automotive applications, siloxane gas contained in car shampoos and car sprays can enter the vehicle interior and adhere to the substrate, causing contact failures and significantly reducing the durability of automotive parts. To address this issue, siloxane gas removal agents have been proposed for air filter applications that contain an inorganic porous material with an average pore diameter of 3 to 20 nm and an acidic compound with an acid dissociation index (pKa) of 2.2 or less and a molecular weight of 1000 or less (see, for example, Patent Document 2).

[0005] While siloxane gas removal is possible, there are concerns that impregnating siloxane gas adsorbents with acidic compounds may cause highly interfering agents to decompose and degrade, significantly reducing adsorption performance and the effectiveness of functionalizing agents. Furthermore, in inorganic porous materials with large average pore sizes, there are concerns about secondary odor generation due to the desorption of adsorbed gases. In other words, there is a need for a gas adsorbent that has excellent siloxane gas removal performance and also suppresses secondary odor generation. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 2008-55318 [Patent Document 2] Japanese Patent Publication No. 2015-44175 [Overview of the project] [Problems that the invention aims to solve]

[0007] The present invention has been made in view of the above, and aims to provide a gas adsorbent that has high siloxane gas removal performance and secondary odor suppression effect. [Means for solving the problem]

[0008] This invention was completed based on these findings, and the following invention is provided. This invention is a gas adsorbent containing two specific types of activated carbon and having a specific average particle size. Specifically, V1 is the pore volume of pores with a pore diameter of 0.4 nm or more and less than 1 nm as determined by GCMC analysis, and V2 is the pore volume of pores with a pore diameter of 1 nm or more and 2 nm or less, and V1 / (V1+V2) is 0.55 or more and the specific surface area is 900 to 1200 m². 2 Activated carbon A and V2 / (V1+V2) at a ratio of 0.55 or higher, with a specific surface area of ​​1500-3000 m². 2 This gas adsorbent contains activated carbon B at a concentration of / g and has an average particle size of 100-900 μm.

[0009] In a preferred embodiment of the gas adsorbent of the present invention, the mass of activated carbon A is 10% by mass or more and 90% by mass or less of the total mass of activated carbon A and activated carbon B.

[0010] In a preferred embodiment of the gas adsorbent of the present invention, the gas adsorbent has a DB / DA ratio of 1.0 or more and 5.0 or less, where DA is the average particle size of activated carbon A and DB is the average particle size of activated carbon B. [Effects of the Invention]

[0011] According to the present invention, it is possible to provide a gas adsorbent that is excellent in the removal performance of siloxane gas and has an effect of suppressing secondary odor.

Brief Description of the Drawings

[0012] [Figure 1] FIG. 1 is a schematic diagram of a collection efficiency measuring device.

Embodiments for Carrying Out the Invention

[0013] The present invention has been achieved as a result of intensive studies on the above problems, that is, a gas adsorbent having high siloxane gas removal performance and an effect of suppressing secondary odor. Hereinafter, the present invention will be described in detail.

[0014] In the gas adsorbent of the present invention, the pore volume of pores having a pore diameter of 0.4 nm or more and less than 1 nm by GCMC analysis is V1, and the pore volume of pores having a pore diameter of 1 nm or more and 2 nm or less is V2, and V1 / (V1 + V2) is 0.55 or more and the specific surface area is 900 to 1200 m 2 / g, and activated carbon A and V2 / (V1 + V2) is 0.55 or more and the specific surface area is 1500 to 3000 m 2 / g, and activated carbon B is contained, and the average particle diameter is 100 to 900 μm.

[0015] The pore region of V1 composed of pores having a pore diameter of 0.4 nm or more and less than 1 nm has low removal performance of siloxane gas because the pore diameter is small with respect to the siloxane gas molecule size. On the other hand, since it is close to the gas molecule size of VOCs such as toluene and has a high intermolecular force, the adsorption retention property is high, that is, there is an effect of suppressing secondary odor.

[0016] On the other hand, the pore region of V2 composed of pores having a pore diameter of 1 nm or more and 2 nm or less has a pore diameter that fits the siloxane gas molecule size, so the adsorption performance of siloxane gas is high. On the other hand, since the pore diameter is large with respect to gas molecules of VOCs such as toluene, the intermolecular force is weak, and there is a concern of secondary odor in which the gas once captured is re-released.

[0017] Therefore, by including activated carbon A, which has a large proportion of pore regions V1 consisting of pores with a diameter of 0.4 nm or more and less than 1 nm, and activated carbon B, which has a large proportion of pore regions V2 consisting of pores with a diameter of 1 nm or more and less than 2 nm, a gas adsorbent is obtained that has excellent siloxane gas removal performance and is effective in suppressing secondary odor generation.

[0018] The pore structure of activated carbon is primarily determined by the activation process, which involves forming pores in the activated carbon material under high-temperature conditions. Adjusting the activation conditions to achieve both a pore volume V1 for pores with a diameter of 0.4 nm or more and less than 1 nm for pores with a diameter of 1 nm or more and less than 2 nm for pores with a diameter of 1 nm or more and less than 2 nm for pores is extremely difficult. This is because if the activation conditions, such as temperature and time, are low, there will be many small holes, but the pore volume and specific surface area will be small. In other words, a sufficient pore volume V2 for pores with a diameter of 1 nm or more and less than 2 nm cannot be obtained, resulting in insufficient siloxane gas removal performance. Conversely, if the activation conditions are high, there will be many large holes, but the pore volume will be large, increasing V2 while V1 for pores with a diameter of 0.4 nm or more and less than 1 nm will decrease, raising concerns about the risk of secondary odor generation.

[0019] The activated carbon A used in the gas adsorbent of the present invention has a pore volume of V1 for pores with a pore diameter of 0.4 nm or more and less than 1 nm, determined by GCMC analysis, and V2 for pores with a pore diameter of 1 nm or more and 2 nm or less. The ratio V1 / (V1+V2) is 0.55 or more, preferably 0.58 or more, and more preferably 0.62 or more. Furthermore, the specific surface area is 900 to 1200 m². 2 It is / g, and 1000~1100m 2 It is preferable that the value is / g. A sufficient secondary odor suppression effect can be obtained when V1 / (V1+V2) is 0.55 or higher. Also, the specific surface area is 900-1200 m². 2 Because the size is close to that of toluene and other VOCs, the intermolecular forces are strong, resulting in high adsorption and retention.

[0020] In addition, the activated carbon B used in the gas adsorbent of the present invention has a pore volume V1 of pores with a pore diameter of 0.4 nm or more and less than 1 nm and a pore volume V2 of pores with a pore diameter of 1 nm or more and 2 nm or less as determined by GCMC analysis, and V2 / (V1 + V2) is 0.55 or more, preferably 0.58 or more, and more preferably 0.62 or more. The specific surface area is 1500~3000m 2 / g, and preferably 1800~2700m 2 / g. When V1 / (V1 + V2) is 0.55 or more, sufficient siloxane gas removal performance can be obtained. Further, when the specific surface area is 1500~3000m 2 / g, by containing many pores suitable for siloxane, the adsorption amount of siloxane can be maximized.

[0021] The gas adsorbent of the present invention is in particulate form, and as the shape, it can be arbitrarily selected from known ones such as spherical, crushed, and columnar. The average particle diameter of the gas adsorbent of the present invention is 100~900μm, and preferably 150~500μm. When used in sheet form, if the particle diameter is less than 100μm, the pressure loss of the sheet increases. Also, when it is larger than 900μm, the contact efficiency of the gas becomes low in terms of performance and sufficient performance cannot be obtained, and there is a concern of causing breakage of the sheet in terms of processing.

[0022] The gas adsorbent of the present invention contains activated carbon A and activated carbon B, and the total mass of activated carbon A and activated carbon B in the total amount of the gas adsorbent is preferably 80% by mass or more, and more preferably 90% by mass or more. Thereby, the effect of achieving both siloxane gas removal and secondary odor generation is more exerted.

[0023] The mass of activated carbon A in the gas adsorbent of the present invention is preferably 10% by mass or more and 90% by mass or less, and more preferably 20% or more and 80% by mass or less, based on the total mass of activated carbon A and activated carbon B. By setting it within the above range, the effect of achieving both siloxane gas removal and secondary odor generation is more exerted.

[0024] In the present invention, the gas adsorbent preferably has a DB / DA ratio of 1.0 to 5.0, and more preferably 1.1 to 3.0, where DA is the average particle size of activated carbon A and DB is the average particle size of activated carbon B. Generally, the smaller the average particle size of activated carbon, the higher the contact efficiency with gas. Therefore, by setting DB / DA to 1.0 to 5.0 as described above, and making the average particle sizes of activated carbon A and activated carbon B the same, or making the average particle size of activated carbon A somewhat smaller than the average particle size of activated carbon B, the gas detached from activated carbon B will come into contact with activated carbon A with a high probability, thereby further suppressing secondary odor generation. As a result, the gas adsorbent will have higher siloxane gas removal performance and further suppress secondary odor generation.

[0025] The activated carbon raw materials for activated carbon A and activated carbon B used in the gas adsorbent of the present invention can be arbitrarily selected from known materials such as coconut shells, charcoal, coal pitch, and phenolic resin, and can be obtained by adjusting the activation conditions for pore formation through high-temperature treatment with steam or chemical treatment with phosphoric acid or zinc chloride. Among these, using coconut shells as the raw material and selecting the steam activation method is more preferable because it is easier to obtain activated carbon with smaller pore sizes.

[0026] The gas adsorbent of the present invention is preferably used in the form of a sheet. That is, the gas adsorbent of the present invention is suitably used in a gas adsorption sheet. When the gas adsorbent is said to be formed in the form of a sheet, methods include dispersing the gas adsorbent between the fibers of a fabric to form a sheet, or connecting the surfaces of the gas adsorbent with an adhesive or the like to form a sheet. The form of the fabric is not particularly limited and can be arbitrarily selected from woven fabrics, knitted fabrics, molded nets, nonwoven fabrics, etc. Among these, nonwoven fabrics are preferred because desired physical properties can be easily obtained by arbitrarily selecting and combining the fiber diameter, fiber length, etc. of the fibers used. Examples of nonwoven fabrics include chemical bonded nonwoven fabrics, wet-type label nonwoven fabrics, spunbond nonwoven fabrics, meltblown nonwoven fabrics, spunlace nonwoven fabrics, and airlaid nonwoven fabrics.

[0027] The basis weight of the gas adsorbent when the gas adsorbent of the present invention is formed into a sheet is 15 to 400 g / m². 2A range of 30-300 g / m² is preferred. 2 Within this range, the gas adsorption capacity is high, and the resulting sheet-like filter material is more preferable because it offers excellent pleating (folding) processability when processed into an air filter.

[0028] The gas adsorbent of the present invention is suitably used in filter media. This filter media comprises two or more layers of nonwoven fabric and the gas adsorbent of the present invention. The gas adsorbent of the present invention is held in at least one of the spaces between one or more layers formed by the two or more layers of nonwoven fabric.

[0029] The amount of gas adsorbent used in a filter medium using the gas adsorbent of the present invention is 40 to 400 g / m³, from the viewpoint of obtaining gas removal efficiency and adsorption capacity when used as a filter medium. 2 A range of 100 to 200 g / m² is preferred, and more preferably 100 to 200 g / m². 2 That is the case.

[0030] The nonwoven fabric of the filter material described above is preferably an electret nonwoven fabric. Being an electret nonwoven fabric is preferable because it allows the filter material to capture airborne dust with higher efficiency.

[0031] Specific manufacturing methods for the filter material include, but are not limited to, a method in which a gas adsorbent and powdered heat-adhesive resin particles are uniformly and quantitatively dispersed onto one nonwoven fabric, the heat-adhesive resin particles are heated and melted with a heater, and then the other nonwoven fabric is laminated and pressed to integrate them, or a method in which a gas adsorbent particle is dispersed while spraying a heated and molten resin onto one nonwoven fabric, and then the other nonwoven fabric is laminated and pressed to integrate them.

[0032] The thickness of the nonwoven fabric described above is preferably 0.08 to 0.60 mm, with a lower limit of 0.15 mm or more and an upper limit of 0.50 mm or less, from the viewpoint of having a certain strength and increasing the area that can be contained in a certain volume when pleated. The filter material described above has two or more layers of nonwoven fabric, and the thicknesses of these nonwoven fabrics may be the same or different.

[0033] The fibers used in the above-mentioned nonwoven fabric can include natural fibers, synthetic fibers, glass fibers, metal fibers, and other inorganic fibers, with synthetic fibers made of thermoplastic resin that can be melt-spun being preferred.

[0034] The air filter equipped with a filter material using the gas adsorbent of the present invention comprises the above-mentioned filter material and an outer frame. Preferably, the filter material is fixed to the outer frame on all four sides. The filter material may be used in sheet form or may be pleated to form a three-dimensional shape with peaks and valleys. [Examples]

[0035] The effects and benefits of the present invention will be illustrated more specifically below with reference to examples, but the present invention is not limited to the following examples.

[0036] [Method for manufacturing filter media using gas adsorbents] A gas adsorbent and polyethylene-based adhesive powder (Abifor1200, manufactured by AbiforAG) (hereinafter referred to as adhesive powder) are blended in a mass ratio of 2 parts gas adsorbent to 1 part adhesive powder. A predetermined amount of this mixture is uniformly scattered onto a spunbond nonwoven fabric made of polyester fibers (Acstar® H2070-1S, manufactured by Toray Industries, Inc., with a thickness of 0.27 mm). The adhesive powder is melted by heating it in a heating furnace at 110°C to 130°C. An electret meltblown nonwoven fabric (basis weight 30 g / m²) is then applied to the surface where the powder was spread. 2 After stacking layers (0.25 mm thick), the material was pressed using a nip roll to obtain a sheet-like filter material of a predetermined thickness.

[0037] (1) Pore volume determined by GCMC analysis The GCMC (Grand Canonical Monte Carlo) method is a numerical simulation technique used to simulate the adsorption behavior of gas molecules and analyze gas adsorption within pores. In this method, nitrogen gas was adsorbed into the pores of activated carbon, and the pore volume was calculated from the gas volume. Specifically, as preparation, 0.05 g of activated carbon or adsorbent was prepared and degassed under reduced pressure at 300°C for 5 hours. Then, using a BELSORP18PLUS-HT instrument manufactured by Nippon Bell, liquid nitrogen at 77 K was gradually adsorbed under conditions of a saturated vapor pressure of 101.3 kPa and a constant temperature bath / pipe temperature of 35°C. The amount of adsorption occurring within a specific pore range was analyzed, and the pore size distribution was calculated. The pore volume was then calculated. For adsorbents containing multiple types of activated carbon, the adsorbent was finely ground in a mortar and pestle, and a sample of 0.05 g was prepared.

[0038] (2) Specific surface area Using the same method as described in (1) above, the specific surface area was calculated from the adsorption isotherms obtained by GCMC analysis.

[0039] (3) Average particle size Using the sieving method, particles were classified into different size ranges using sieves, and the mass of particles contained in each range was measured. Then, the average particle size was calculated based on the center value and mass ratio of each range. Specifically, the mass-average particle size was calculated in accordance with JIS K1474:2014 (Activated Carbon Test Method) "7.5 Effective diameter, uniformity coefficient and average particle size". Before the test, the activated carbon or adsorbent was dried at 115°C for 3 hours or more, and JIS standard sieves (mesh openings ranging from several tens of μm to 1 mm) were stacked from coarse to fine, and shaken for 15 minutes with a shaker (amplitude 45 mm horizontally, 200 reciprocations per minute). The mass of the activated carbon or adsorbent remaining in each sieve was compared to the total mass of the sample, and the percentage was calculated to determine the average particle size.

[0040] (4) Siloxane gas saturation adsorption capacity (g / m³) 2 ) The sheet-like filter media using the gas adsorbent obtained in the above [Method for Manufacturing Filter Media Using Gas Adsorbent] was cut into a 10cm x 10cm square, placed in a dryer heated to 80°C, and dried for 2 hours. The mass (g) of the removed filter media was measured using an electronic balance. The obtained measurement value was taken as m1 (g). Next, siloxane gas (D5) was saturated in a 10L desiccator controlled to 50%RH humidity, and the filter media whose mass had been measured was placed in it and left for 24 hours. Siloxane D5 (decamethylcyclopentasiloxane) is an organic compound containing silicon, and its chemical formula is C10H30O5Si5, which has a cyclic structure. In this application, siloxane D5 was selected as a representative cyclic siloxane. The mass (g) of the filter media after it was removed from the desiccator was measured using an electronic balance. The obtained measurement value was taken as m2 (g). Next, the saturation adsorption capacity of siloxane gas per unit area of ​​the filter material was calculated using the following formula. • Siloxane gas saturation adsorption capacity = (m² - m¹) / (0.1 × 0.1) (g / m²) 2 ) (5) Toluene saturation adsorption capacity (g / m³) 2 ) The sheet-like filter media using the gas adsorbent obtained in the above [Method for Manufacturing Filter Media Using Gas Adsorbent] was cut into a 10cm x 10cm rectangle, placed in a dryer heated to 80°C, and dried for 2 hours. The mass (g) of the removed filter media was measured using an electronic balance. The obtained measurement was taken as m3 (g). Next, toluene was saturated in a 10L desiccator controlled to 50%RH humidity, and the filter media whose mass had been measured was placed in it and left for 24 hours. The mass (g) of the filter media after being removed from the desiccator was measured using an electronic balance. The obtained measurement was taken as m4 (g). Next, the toluene saturation adsorption capacity per unit area of ​​the filter media was calculated using the following formula. • Toluene saturation adsorption capacity = (m4 - m3) / (0.1 × 0.1) (g / m 2 ) (6) Toluene elimination rate (%) (2) Saturated adsorption amount of toluene (g / m³) 2The mass (g) of the toluene-saturated sheet filter media obtained in ) was measured using an electronic balance after 6 hours of removal from the desiccator. The obtained measurement value was taken as m5 (g). Next, the amount of toluene desorbed per unit area of ​​the filter media and the toluene desorption rate were calculated using the following formula. • Amount of toluene removed = (m4-m5) / (0.1×0.1) (g / m 2 ) • Toluene desorption rate = (m4-m5) / m4 (%) (7) Pressure loss A sheet-like filter media using the gas adsorbent obtained in the above [Method for Manufacturing Filter Media Using Gas Adsorbent] was sampled in a 10cm x 10cm rectangle, and the pressure loss was measured using the collection efficiency measuring device shown in Figure 1. In this collection efficiency measuring device shown in Figure 1, a dust storage box 2 and a static eliminator 9 are connected to the upstream side of the sample holder 1 where the measurement sample M is set, and a flow meter 3, a flow control valve 4, and a blower 5 are connected to the downstream side. In addition, a particle counter 6 is used in the sample holder 1, and the number of dust particles on the upstream side and the number of dust particles on the downstream side of the measurement sample M can be measured via a switching cock 7. Furthermore, the sample holder 1 is equipped with a pressure gauge 8, which can read the static pressure difference between the upstream and downstream sides of the measurement sample M. The measurement sample M was set in the sample holder 1, the airflow was adjusted with the flow control valve 4 so that the filter passage speed was 6.5 m / min, and the static pressure difference of the pressure gauge 8 was read. The average value of the three measurement samples was taken as the final pressure loss.

[0041] (8) External inspection The sheet-like filter media using the gas adsorbent obtained in the above [Method for Manufacturing Filter Media Using Gas Adsorbent] was taken in a 10cm x 10cm square, and the presence or absence of penetration of the activated carbon was checked from the electret meltblown nonwoven fabric side. If there was no penetration, it was considered to be fine.

[0042] [Example 1] Based on GCMC analysis, V1 represents the pore volume of pores with a diameter of 0.4 nm or more and less than 1 nm, and V2 represents the pore volume of pores with a diameter of 1 nm or more and less than 2 nm. With V1 = 0.20 cc / g, V2 = 0.10 cc / g, V1 / (V1+V2) = 0.67, and a specific surface area of ​​1100 m². 2 Activated carbon A manufactured by Kuraray Co., Ltd., with a particle size of 300 μm and a V1 of 0.20 cc / g, a V2 of 0.50 cc / g, a V2 / (V1+V2) of 0.71 or higher, and a specific surface area of ​​2000 m². 2 An adsorbent consisting of activated carbon B manufactured by Kuraray Co., Ltd., with a particle size of 300 μm, was used. The average particle size of the gas adsorbent was 300 μm, and the mass of activated carbon A was 50% by mass of the total mass of activated carbon A and activated carbon B. Using this gas adsorbent, a filter media containing the gas adsorbent was manufactured by the method described in [Method for manufacturing filter media using gas adsorbent]. The gas adsorbent was applied at a concentration of 150 g / m³. 2 The filter material used had a thickness of 0.9 mm. The measurements (1) to (8) above were performed using the obtained filter material.

[0043] [Example 2] Based on GCMC analysis, V1 represents the pore volume of pores with a diameter of 0.4 nm or more and less than 1 nm, and V2 represents the pore volume of pores with a diameter of 1 nm or more and less than 2 nm. With V1 = 0.20 cc / g, V2 = 0.10 cc / g, V1 / (V1+V2) = 0.67, and a specific surface area of ​​1100 m². 2 Activated carbon A manufactured by Kuraray Co., Ltd., with a particle size of 260 μm and a density of 0.20 cc / g, V1 is 0.20 cc / g, V2 is 0.50 cc / g, V2 / (V1+V2) is 0.71, and the specific surface area is 2000 m². 2 An adsorbent consisting of activated carbon B manufactured by Kuraray Co., Ltd., with a concentration of 150 g / m³ and an average particle size of 400 μm, was used. The average particle size of the gas adsorbent was 330 μm, and the mass of activated carbon A was 50% by mass of the total mass of activated carbon A and activated carbon B. Using this gas adsorbent, a filter media containing the gas adsorbent was manufactured by the method described in [Method for manufacturing filter media using gas adsorbent]. The gas adsorbent was applied at a concentration of 150 g / m³. 2 The filter material used had a thickness of 0.9 mm. The measurements (1) to (8) above were performed using the obtained filter material.

[0044] [Comparative Example 1] Based on GCMC analysis, V1 represents the pore volume of pores with a diameter of 0.4 nm or more and less than 1 nm, and V2 represents the pore volume of pores with a diameter of 1 nm or more and less than 2 nm. With V1 = 0.20 cc / g, V2 = 0.10 cc / g, V1 / (V1+V2) = 0.67, and a specific surface area of ​​1100 m². 2 An adsorbent consisting of activated carbon A manufactured by Kuraray Co., Ltd., with a concentration of 150 g / m³ and an average particle size of 300 μm, was used. The mass of activated carbon A was 100% by mass of the sum of the masses of activated carbon A and activated carbon B. Using this gas adsorbent, a filter media containing the gas adsorbent was manufactured by the method described in [Method for Manufacturing Filter Media Using Gas Adsorbent]. The gas adsorbent was applied at a concentration of 150 g / m³. 2 The filter material used had a thickness of 0.9 mm. The measurements (1) to (8) above were performed using the obtained filter material.

[0045] [Comparative Example 2] Based on GCMC analysis, V1 represents the pore volume of pores with a diameter of 0.4 nm or more and less than 1 nm, and V2 represents the pore volume of pores with a diameter of 1 nm or more and less than 2 nm. With V1 = 0.20 cc / g, V2 = 0.50 cc / g, and V2 / (V1+V2) = 0.71, the specific surface area is 2000 m². 2 An adsorbent consisting of activated carbon B manufactured by Kuraray Co., Ltd., with a concentration of 150 g / m³ and an average particle size of 400 μm, was used. The mass of activated carbon A was 0% by mass relative to the sum of the masses of activated carbon A and activated carbon B. Using this gas adsorbent, a filter media containing the gas adsorbent was manufactured by the method described in [Method for Manufacturing Filter Media Using Gas Adsorbent]. The gas adsorbent was applied at a concentration of 150 g / m³. 2 The filter material used had a thickness of 0.9 mm. The measurements (1) to (8) above were performed using the obtained filter material.

[0046] [Comparative Example 3] Based on GCMC analysis, V1 represents the pore volume of pores with a diameter of 0.4 nm or more and less than 1 nm, and V2 represents the pore volume of pores with a diameter of 1 nm or more and less than 2 nm. With V1 = 0.20 cc / g, V2 = 0.10 cc / g, V1 / (V1+V2) = 0.67, and a specific surface area of ​​1100 m². 2Activated carbon A manufactured by Kuraray Co., Ltd., with a particle size of 1000 μm (1 mm) and V1 is 0.20 cc / g, V2 is 0.50 cc / g, V2 / (V1+V2) is 0.71, and the specific surface area is 2000 m². 2 An adsorbent consisting of activated carbon B manufactured by Kuraray Co., Ltd., with a concentration of 150 g / m³ and an average particle size of 300 μm, was used. The average particle size of the gas adsorbent was 930 μm, and the mass of activated carbon A was 90% by mass of the total mass of activated carbon A and activated carbon B. Using this gas adsorbent, a filter media containing the gas adsorbent was manufactured by the method described in [Method for manufacturing filter media using gas adsorbent]. The gas adsorbent was applied at a concentration of 150 g / m³. 2 The filter material used had a thickness of 1.8 mm. The measurements (1) to (8) above were performed using the obtained filter material.

[0047] [Comparative Example 4] Based on GCMC analysis, V1 represents the pore volume of pores with a diameter of 0.4 nm or more and less than 1 nm, and V2 represents the pore volume of pores with a diameter of 1 nm or more and less than 2 nm. With V1 = 0.20 cc / g, V2 = 0.10 cc / g, V1 / (V1+V2) = 0.67, and a specific surface area of ​​1100 m². 2 Activated carbon A manufactured by Kuraray Co., Ltd., with a density of 0.20 cc / g and an average particle size of 50 μm, and V1 is 0.20 cc / g, V2 is 0.50 cc / g, V2 / (V1+V2) is 0.71, and the specific surface area is 2000 m². 2 An adsorbent consisting of activated carbon B manufactured by Kuraray Co., Ltd., with a particle size of 50 μm, was used. The average particle size of the gas adsorbent was 50 μm, and the mass of activated carbon A was 90% by mass of the total mass of activated carbon A and activated carbon B. Using this gas adsorbent, a filter media containing the gas adsorbent was manufactured by the method described in [Method for manufacturing filter media using gas adsorbent]. The gas adsorbent was applied at a concentration of 150 g / m³. 2 The filter material used had a thickness of 0.7 mm. The measurements (1) to (8) above were performed using the obtained filter material.

[0048] Table 1 shows the evaluation results for the filter media using the gas adsorbents of Examples 1-2 and Comparative Examples 1-4.

[0049] [Table 1]

[0050] In Example 1, by including activated carbon A, which is suitable for suppressing secondary odor generation, and activated carbon B, which is suitable for removing siloxane gas, the saturation adsorption capacity for siloxane gas and toluene was high, and the toluene desorption rate was also low, meaning that it was effective in suppressing secondary odor generation. Furthermore, pressure loss and visual inspection were also good.

[0051] In Example 2, because activated carbon A with a small average particle size was used, the toluene desorption rate was even lower compared to Example 1, resulting in a greater secondary odor suppression effect.

[0052] In Comparative Example 1, the toluene saturation adsorption capacity was high and the toluene desorption rate was low, meaning it was effective in suppressing secondary odor generation, and pressure drop and visual inspection were also good. However, the siloxane gas saturation adsorption capacity was small, and the siloxane gas removal performance was insufficient.

[0053] In Comparative Example 2, the saturation adsorption capacity for siloxane gas and toluene was high, and pressure drop and visual inspection were also good, but the toluene desorption rate was high. In other words, the secondary odor suppression effect was insufficient.

[0054] In Comparative Example 3, the saturation adsorption capacity for siloxane gas and toluene was high, and the toluene desorption rate was also low, meaning it was effective in suppressing secondary odor generation, and the pressure drop was also good. On the other hand, because it contained a large amount of activated carbon with a large average particle size, many instances of activated carbon penetrating the surface of the electret meltblown nonwoven fabric were observed, resulting in an unsatisfactory appearance.

[0055] In Comparative Example 4, the saturation adsorption capacity for siloxane gas and toluene was high, and the toluene desorption rate was also low, meaning it was effective in suppressing secondary odor generation, and the appearance was also good. On the other hand, the pressure loss of the filter was large due to the large amount of activated carbon with a small average particle size. [Industrial applicability]

[0056] The gas adsorbent of the present invention is preferably used in air filter media such as air filters for purifying the air inside vehicles such as automobiles and railway cars, 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, building air conditioning filters, and industrial cleanroom filters. [Explanation of Symbols]

[0057] 1: Sample holder 2: Dust storage box 3:Flow meter 4: Flow control valve 5: Blower 6: Particle Counter 7: Switching valve 8: Pressure gauge 9: Static eliminator M: Measurement sample

Claims

1. Based on GCMC analysis, V1 is the pore volume of pores with a diameter of 0.4 nm or more and less than 1 nm, and V2 is the pore volume of pores with a diameter of 1 nm or more and 2 nm or less. If V1 / (V1+V2) is 0.55 or more, the specific surface area is 900 to 1200 m². ２ Activated carbon A and V2 / (V1+V2) at a ratio of 0.55 or higher, with a specific surface area of ​​1500-3000 m². ２ A gas adsorbent containing activated carbon B at a concentration of / g, with an average particle size of 100 to 900 μm.

2. The gas adsorbent according to claim 1, wherein the mass of activated carbon A is 10% by mass or more and 90% by mass or less of the total mass of activated carbon A and activated carbon B.

3. The gas adsorbent according to claim 1, wherein when the average particle size DA of activated carbon A and the average particle size DB of activated carbon B, DB / DA is 1.0 or more and 5.0 or less.

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