Deodorizing sheet

Abstract

To provide a deodorizing sheet capable of efficiently removing odor materials, such as methyl mercaptan, under an aeration condition.SOLUTION: A deodorizing sheet includes a fibrous active carbon layer containing a fibrous active carbon. The deodorizing sheet is preferably one in which a nonwoven fabric layer containing fiber other than fibrous active carbon, a fibrous active carbon layer containing the fibrous active carbon, and a nonwoven fabric layer containing fiber other than fibrous active carbon are laminated one upon another in this order.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a deodorizing sheet. [Background technology]

[0002] There is an increasing demand for deodorizing sanitary products in medical settings, homes, etc. The main odors that pollute indoor air are human body odor, toilet odor, putrid odor, etc., and their main components are hydrogen sulfide, methyl mercaptan, ammonia, and trimethylamine, which are generated when organic matter is decomposed by microorganisms.

[0003] An adsorbent sheet is known which is made by laminating an activated carbon sheet and an air-permeable reinforcing sheet, in which an adsorbent for acidic substances is impregnated into the activated carbon sheet and an adsorbent for alkaline substances is impregnated into the air-permeable sheet (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 6-39238 Summary of the Invention [Problem to be solved by the invention]

[0005] However, according to the investigations of the present inventors, when the adsorbent sheet disclosed in Patent Document 1 is used in the filter of an air purifier, there is a problem that odors remain in the air purifier during the initial operation of the fan, etc. Therefore, the main object of the present invention is to solve the above problem and to provide a deodorizing sheet that can efficiently remove odorous substances such as methyl mercaptan under ventilated conditions. [Means for solving the problem]

[0006] The present inventors have conducted extensive research to solve the above problems and have discovered that using fibrous activated carbon as the filter material for the deodorizing sheet is effective. The present invention was completed as a result of further research.

[0007] That is, the present invention provides the following aspects of the invention. Item 1. A deodorizing sheet comprising a fibrous activated carbon layer containing fibrous activated carbon. Item 2. The deodorizing sheet according to Item 1, comprising a nonwoven fabric layer containing fibers other than fibrous activated carbon, a fibrous activated carbon layer containing the fibrous activated carbon, and a nonwoven fabric layer containing fibers other than fibrous activated carbon, laminated in this order. Item 3. The deodorizing sheet according to Item 2, wherein the fibrous activated carbon layer contains 90% by mass or more of the fibrous activated carbon. Item 4. The deodorizing sheet according to Item 2 or 3, wherein the ratio of the mass of the activated carbon contained in the deodorizing sheet to the mass of the deodorizing sheet is 70 to 95 mass %. Item 5. The deodorizing sheet according to any one of Items 2 to 4, wherein the fibers constituting the nonwoven fabric layer and the fibrous activated carbon constituting the fibrous activated carbon layer are entangled on the surface portions of the nonwoven fabric layer and the fibrous activated carbon layer, thereby integrating the nonwoven fabric layer and the fibrous activated carbon layer. Item 6. The deodorizing sheet according to any one of Items 2 to 5, wherein the nonwoven fabric layer contains a long-fiber nonwoven fabric and is not embossed. Item 7. The deodorizing sheet according to any one of Items 2 to 6, wherein the ratio of the thickness of the fibrous activated carbon layer to the thickness per layer of the nonwoven fabric layer (thickness of the fibrous activated carbon layer / thickness per layer of the nonwoven fabric layer) is 20 to 50. Item 8. The apparent density of the fibrous activated carbon layer is 0.11 g / cm 3 is , term 8. The sheet according to any one of 1 to 7. [Effects of the Invention]

[0008] The deodorizing sheet of the present invention contains fibrous activated carbon, and therefore can efficiently remove odorous substances such as methyl mercaptan under aeration conditions. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a schematic cross-sectional view showing a deodorizing sheet according to a first embodiment. [Figure 2] FIG. 4 is a cross-sectional view showing a deodorizing sheet according to a second embodiment. [Figure 3] FIG. 2 is a schematic diagram illustrating a method for measuring the pressure loss of a deodorizing sheet according to the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0010] The deodorizing sheet of the present invention includes a fibrous activated carbon layer containing fibrous activated carbon. Preferred embodiments of the present invention will be described below. However, the following embodiments are merely illustrative. The present invention is not limited to the following embodiments.

[0011] (First embodiment) Fig. 1 is a cross-sectional schematic diagram showing a deodorizing sheet of a first embodiment. As shown in Fig. 1, the deodorizing sheet 1 of the present invention is formed by laminating, in this order, a nonwoven fabric layer 3 containing fibers other than fibrous activated carbon, a fibrous activated carbon layer 2 containing fibrous activated carbon, and a nonwoven fabric layer 3 containing fibers other than fibrous activated carbon. This configuration reduces the pressure loss of the deodorizing sheet 1, while increasing the content of fibrous activated carbon throughout the deodorizing sheet 1, allowing for more efficient removal of odorous substances such as methyl mercaptan under ventilation conditions.

[0012] In the deodorizing sheet 1 shown in Fig. 1, the fibers constituting the nonwoven fabric layer 3 and the fibrous activated carbon constituting the fibrous activated carbon layer 2 are entangled on the surface portions of the nonwoven fabric layer 3 and the fibrous activated carbon layer 2, thereby integrating the nonwoven fabric layer 3 and the fibrous activated carbon layer 2. Examples of the entanglement method include a needle punching method and a water punching method, and needle punching is preferred. The materials and each layer constituting the deodorizing sheet 1 of the first embodiment will be described in detail below.

[0013] <Fiber activated carbon> In the present invention, any type of fibrous activated carbon can be used, for example, a fibrous activated carbon produced by infusibilizing fibers such as polyacrylonitrile-based, rayon-based, phenolic resin-based, coal pitch-based, or petroleum pitch-based fibers, optionally carbonizing them, and then activating them by holding them in an atmosphere containing water vapor and carbon dioxide at a predetermined temperature for a predetermined time. Among these, coal pitch-based, petroleum pitch-based, and polyacrylonitrile-based fibrous activated carbons are preferred. The fibrous activated carbon may be used alone or in combination of two or more types.

[0014] In the present invention, the fiber diameter of the fibrous activated carbon is not particularly limited, but is preferably about 7 to 25 μm, more preferably about 10 to 20 μm. The fiber diameter of the fibrous activated carbon is a value determined by the method described in JIS K1477:2007.

[0015] In the present invention, the specific surface area of ​​the fibrous activated carbon is not particularly limited, but is preferably 500 to 2100 m 2 In particular, from the viewpoint of efficiently removing odorous substances such as methyl mercaptan under aeration conditions while more easily suppressing an increase in pressure loss due to deformation of the fibrous activated carbon under aeration conditions, the specific surface area of ​​the fibrous activated carbon is preferably 1200 to 1850 m 2 / g is preferable, and 1200 to 1400 2 / g is more preferable. The specific surface area of ​​the fibrous activated carbon is a value determined by the BET method (single point method) described in JIS K1477:2007.

[0016] In the present invention, the tensile strength of the fibrous activated carbon is not particularly limited, but is preferably 150 to 400 N / mm 2 In particular, from the viewpoint of efficiently removing odorous substances such as methyl mercaptan under aeration conditions while more easily suppressing an increase in pressure loss due to deformation of the fibrous activated carbon under aeration conditions, the tensile strength of the fibrous activated carbon is set to 240 to 280 N / mm 2 The tensile strength of the fibrous activated carbon is a value determined by the method described in JIS K1477:2007.

[0017] The fibrous activated carbon can be impregnated with a chemical agent for removing specific odorous substances. For example, to remove alkaline odorous substances such as ammonia, the fibrous activated carbon can be impregnated with one or more of inorganic acids, inorganic salts, and acidic organic compounds, specifically ferrous chloride, ferrous sulfate, sulfuric acid, phosphoric acid, citric acid, malic acid, etc. Furthermore, to remove acidic odorous substances such as hydrogen sulfide, the fibrous activated carbon can be impregnated with one or more of inorganic bases, inorganic acids, and basic organic compounds, specifically potassium carbonate, sodium carbonate, calcium carbonate, potassium permanganate, etc. On the other hand, impregnation of the fibrous activated carbon with a chemical agent for removing the specific odorous substance improves the removal performance of the specific odorous substance, but the removal performance of odorous substances other than the specific odorous substance may be reduced due to the effect of pore blockage of the fibrous activated carbon caused by the impregnation of the chemical agent. Therefore, for example, from the viewpoint of further improving the balance of the removal performance of alkaline odorous substances and acidic odorous substances under aeration conditions, the amount of chemical agent impregnated in the fibrous activated carbon for removing the above-mentioned specific odorous substances is preferably 5% by mass or less, more preferably 3% by mass or less, even more preferably 1% by mass or less, and particularly preferably 0% by mass (no chemical agent contained).

[0018] <Fiber activated carbon layer 2> The deodorizing sheet 1 of the first embodiment includes a fibrous activated carbon layer 2.

[0019] The fibrous activated carbon layer 2 contains the above-mentioned fibrous activated carbon, which allows efficient removal of odorous substances such as methyl mercaptan under aeration conditions.

[0020] The fibrous activated carbon layer 2 may contain components other than the fibrous activated carbon. Examples of such components include granular or powdered activated carbon, pulp, heat-fusible fibers, and a thermoplastic resin as a binder component (excluding the thermoplastic resin contained in the heat-fusible fibers) (hereinafter, the pulp, the heat-fusible fibers, and the thermoplastic resin as the binder component may be collectively referred to as the "binder component").

[0021] When granular or powdered activated carbon is contained in the fibrous activated carbon layer 2, the content is, for example, 10 to 75 mass%, and preferably 20 to 65 mass%. On the other hand, the fibrous activated carbon layer 2 may be substantially free of granular or powdered activated carbon, and specific content ratios include 5 mass% or less, 3 mass% or less, and 1 mass% or less, with 0 mass% being preferred (no granular or powdered activated carbon is contained).

[0022] The pulp does not fix the filter material by heat fusion itself, but rather fibrillates the filter material and forms a shape by entangling it. Examples of the pulp include cellulosic pulp and acrylic pulp. The freeness of the pulp, measured in accordance with JIS P 8121-2:2012, is preferably 10 to 200 mL. The preferred melting point of the pulp is, for example, 150°C or higher, preferably 200°C or higher. In the present invention, if the pulp does not have a melting point, the softening point is used as the melting point. In the present invention, the melting point is measured using a PerkinElmer DSC-7 differential scanning calorimeter at a heating rate of 20°C / min. When the pulp is contained in the fibrous activated carbon layer 2, the content ratio thereof is, for example, 1 to 25% by mass, preferably 3 to 20% by mass. On the other hand, from the viewpoint of making it easier for the fibrous activated carbon layer 2 to have the apparent density described below, the fibrous activated carbon layer 2 may be substantially free of pulp, and a specific content ratio may be 0.5 mass% or less, with 0 mass% (no pulp) being preferred.

[0023] The heat-fusible fibers, also known as binder fibers, typically melt when heated, allowing them to fix filter media and other components. The heat-fusible component contained in the heat-fusible fibers preferably has a melting point of 80 to 140°C. Specific examples of the heat-fusible component include polyolefin resins such as polyethylene and polypropylene, and polyester resins such as copolymerized polyethylene terephthalate, which is copolymerized with a copolymerization component such as isophthalic acid. Examples of heat-fusible fibers that can be contained in the fibrous activated carbon layer 2 include fully fusible fibers composed of a single heat-fusible component, and core-sheath heat-fusible fibers in which the sheath contains a heat-fusible component and the core contains a synthetic resin component whose melting point is preferably at least 20°C, more preferably at least 30°C, higher than that of the sheath. Specific examples of the synthetic resin component contained in the sheath include polyethylene terephthalate.

[0024] The fineness of the heat-fusible fibers is 1 to 20 dtex, and the fiber length of the heat-fusible fibers is 10 to 70 mm.

[0025] When the fibrous activated carbon layer 2 contains heat-fusible fibers, the content thereof is, for example, 10 to 50% by mass, and preferably 10 to 30% by mass. On the other hand, particularly in the first embodiment, from the viewpoint of ensuring more air flow paths in the fibrous activated carbon layer 2 and reducing pressure loss in the deodorizing sheet 1 while increasing the content of fibrous activated carbon in the entire deodorizing sheet 1 and more efficiently removing odorous substances such as methyl mercaptan under aeration conditions, the fibrous activated carbon layer 2 can be substantially free of heat-fusible fibers, and specific content percentages include 5% by mass or less, 3% by mass or less, and 1% by mass or less, with 0% by mass (no heat-fusible fibers) being preferred.

[0026] Examples of the thermoplastic resin used as the binder component (excluding the thermoplastic resin contained in the heat-fusible fibers) include olefin resins (polyethylene, polypropylene, ethylene-vinyl acetate copolymer, ethylene-(meth)acrylic acid copolymer, ethylene-(meth)acrylic acid ester copolymer, etc.), vinyl acetate resins (polyvinyl acetate, vinyl acetate-vinyl chloride copolymer, etc.), polyvinyl alcohol resins (polyvinyl alcohol, ethylene-vinyl alcohol copolymer, etc.), acrylic resins, styrene resins (polystyrene, AS resin, ABS resin, etc.), polyester resins, polyamide resins, thermoplastic polyurethane resins, cellulose derivatives (cellulose ethers such as methyl cellulose, ethyl cellulose, carboxymethyl cellulose, and hydroxyethyl cellulose, and cellulose esters such as cellulose acetate), natural resins (shellac, rosin, etc.), and polysaccharides (sodium alginate, tragacanth gum, gum arabic, pectin, chitosan, and gelatin). When the thermoplastic resin is contained in the fibrous activated carbon layer 2, the content ratio is, for example, 10 to 50% by mass, preferably 10 to 30% by mass. On the other hand, particularly in the first embodiment, in order to ensure more air flow paths in the fibrous activated carbon layer 2 and reduce pressure loss in the deodorizing sheet 1 while increasing the content of fibrous activated carbon in the entire deodorizing sheet 1 and more efficiently removing odorous substances such as methyl mercaptan under ventilation conditions, the fibrous activated carbon layer 2 can be made substantially free of the above-mentioned thermoplastic resin, and specific content percentages include 5% by mass or less, 3% by mass or less, and 1% by mass or less, with 0% by mass (no thermoplastic resin (excluding thermoplastic resin contained in heat-fusible fibers)) being preferred.

[0027] The content of fibrous activated carbon in the fibrous activated carbon layer 2 is preferably 80% by mass or more, more preferably 90% by mass or more, even more preferably 95% by mass or more, and particularly preferably 99% by mass or more, from the viewpoints of ensuring a large number of air flow paths in the fibrous activated carbon layer 2, reducing pressure loss in the deodorizing sheet 1, and increasing the content of fibrous activated carbon in the entire deodorizing sheet 1 to more efficiently remove odorous substances such as methyl mercaptan under aeration conditions. Furthermore, the fibrous activated carbon layer 2 can be made solely of fibrous activated carbon. From the same viewpoint, the content of the binder component in the fibrous activated carbon layer 2 is preferably 20% by mass or less, more preferably 10% by mass or less, even more preferably 5% by mass or less, particularly preferably 1% by mass or less, and even more preferably 0% by mass (no binder component).

[0028] The form of the fibrous activated carbon layer 2 can be a fibrous activated carbon aggregate in which fibrous activated carbon is aggregated to form the fibrous activated carbon layer 2. The fibrous activated carbon aggregate is not particularly limited, but can be a fibrous activated carbon aggregate in which fibrous activated carbon is fixed with heat-fusible fibers or pulp, or a cotton-like or felt-like fibrous activated carbon aggregate in which fibrous activated carbon is integrated by being entangled with each other without using a binder component, and a cotton-like or felt-like fibrous activated carbon aggregate in which fibrous activated carbon is integrated by being entangled with each other without using a binder component is preferred. Examples of fibrous activated carbon aggregates in which fibrous activated carbon is fixed with heat-fusible fibers or pulp include needle-punched nonwoven fabrics and wet-laid paper-making nonwoven fabrics.

[0029] The mass of the fibrous activated carbon layer 2 is not particularly limited, but from the viewpoint of more efficiently removing odorous substances such as methyl mercaptan under aeration conditions, it is preferable that the mass be 120 g / m 2 More than 140g / m 2 More than 180g / m 2Although there is no particular upper limit to the mass of the fibrous activated carbon layer 2, from the viewpoint of reducing the pressure loss of the deodorizing sheet 1 while increasing the content of fibrous activated carbon in the entire deodorizing sheet 1 and more efficiently removing odorous substances such as methyl mercaptan under ventilation conditions, it is more preferable that the mass of the fibrous activated carbon layer 2 is 300 g / m 2 Preferably less than 240 g / m 2 Less than 220 g / m is more preferable. 2 is more preferable.

[0030] The thickness of the fibrous activated carbon layer 2 is not particularly limited, but is preferably 1500 to 3000 μm, more preferably 1600 to 2000 μm, from the viewpoint of reducing the pressure loss of the deodorizing sheet 1 while increasing the content of fibrous activated carbon throughout the deodorizing sheet 1 and more efficiently removing odorous substances such as methyl mercaptan under aeration conditions. The thickness of the fibrous activated carbon layer 2 is measured at 10 random points by observing the deodorizing sheet 1 from the cross-sectional direction using a microscope, VHX-5000 manufactured by Keyence Corporation, and the average value of the thicknesses at the 10 points is defined as the thickness of the fibrous activated carbon layer 2. The apparent density of the fibrous activated carbon layer 2 is 0.12 g / cm. 3 The following are listed: 0.07 to 0.12 g / cm 3 The upper limit of the apparent density is preferably 0.11 g / cm. 3 The apparent density can be determined from the mass of the fibrous activated carbon layer 2 and the thickness of the fibrous activated carbon layer 2.

[0031] <Nonwoven fabric layer 3 containing fibers other than fibrous activated carbon> In the deodorizing sheet 1 of the first embodiment, the nonwoven fabric layer 3 serves to maintain the shape of the fibrous activated carbon layer 2 and to prevent the fibrous activated carbon and parts thereof from falling off from the fibrous activated carbon layer 2.

[0032] Examples of fiber materials (fiber materials other than fibrous activated carbon) constituting the nonwoven fabric layer 3 include synthetic fibers such as polyester fibers, polyamide fibers, polyacrylic fibers, polypropylene fibers, and polyvinyl chloride fibers, natural fibers such as cotton, hemp, and wool, and recycled fibers such as cupra rayon, viscose rayon, and lyocell, as well as any fiber other than fibrous activated carbon. The content of fibrous activated carbon in the nonwoven fabric layer 3 is 5% by mass or less, 3% by mass or less, or 1% by mass or less, and 0% by mass (no fibrous activated carbon) is preferred.

[0033] The nonwoven fabric layer 3 may be in the form of a long-fiber nonwoven fabric or a short-fiber nonwoven fabric. Examples of long-fiber nonwoven fabrics include spunbond nonwoven fabrics, tow-spread nonwoven fabrics, and melt-blown nonwoven fabrics made of continuous fibers. Examples of short-fiber nonwoven fabrics include needle-punched nonwoven fabrics and wet-laid papermaking nonwoven fabrics. When the content of fibrous activated carbon in the fibrous activated carbon layer 2 is increased to, for example, 80% by mass or more, the nonwoven fabric preferably contains a long-fiber nonwoven fabric, and more preferably contains a nonwoven fabric made of continuous long fibers, in order to further enhance the bonding between the fibrous activated carbon layer 2 and the nonwoven fabric layer 3 through entanglement. The long-fiber nonwoven fabric preferably has an average fiber length of 100 mm or more, and more preferably 300 mm or more. In particular, a nonwoven fabric containing a tow-spread long-fiber web is preferred, in order to further enhance the bonding between the fibrous activated carbon layer 2 and the nonwoven fabric layer 3 through entanglement, since the long fibers are easily unraveled.

[0034] Furthermore, it is preferable that the nonwoven fabric used for the nonwoven fabric layer 3 is not embossed. This increases the degree of freedom for each fiber constituting the nonwoven fabric layer 3, and further improves the bonding strength due to the entanglement between the fibrous activated carbon layer 2 and the nonwoven fabric layer 3, which will be described later. Examples of such nonwoven fabrics include nonwoven fabrics formed by stretching laminated webs.

[0035] The tensile strength (N / 5cm) of the nonwoven fabric constituting the nonwoven fabric layer 3 is, for example, 10 to 100 N / 5cm in the MD (machine direction) and 10 to 100 N / 5cm in the CD (direction perpendicular to the MD). The ratio of the tensile strength in the MD to the tensile strength in the CD (MD / CD) is, for example, 0.7 to 1.3, preferably 0.9 to 1.1. By reducing the difference between the MD and CD strengths in this way, it becomes easier to reduce pressure loss when the fibrous activated carbon layer 2 is laminated to form the deodorizing sheet 1. In the present invention, the tensile strength of the nonwoven fabric is measured and calculated as follows. That is, in accordance with JIS L 1913:2010 6.3, a test piece having a width of 50 mm and a length of 200 mm is measured using a Tensilon RTM-500 model manufactured by Toyo Baldwin Co., Ltd., under conditions of a gripping distance of 100 mm and a pulling speed of 100 mm / min, and the average value of 10 samples is calculated and used as the tensile strength.

[0036] The thickness of each nonwoven fabric layer 3 is, for example, 20 to 80 μm, preferably 40 to 70 μm. The thickness of the nonwoven fabric layer 3 in the deodorizing sheet 1 is measured at 10 random points by observing the deodorizing sheet 1 from the cross-sectional direction using a microscope, VHX-5000 manufactured by Keyence Corporation, and the average value of the thicknesses at the 10 points is defined as the thickness of the nonwoven fabric layer 3.

[0037] The mass of each nonwoven fabric layer 3 is 5 to 50 g / m 2 and 15 to 25 g / m 2 The apparent density of the nonwoven fabric layer 3 is more preferably 0.10 to 0.50 g / cm. 3 is preferable, and 0.30 to 0.40 g / cm 3 The apparent density of the nonwoven fabric layer 3 is determined from the mass of the nonwoven fabric layer 3 and the thickness of the nonwoven fabric layer 3.

[0038] <Deodorizing sheet 1> The deodorizing sheet 1 in the first embodiment is formed by laminating, in this order, a nonwoven fabric layer 3 containing fibers other than fibrous activated carbon, a fibrous activated carbon layer 2 containing the fibrous activated carbon, and a nonwoven fabric layer 3 containing fibers other than fibrous activated carbon.

[0039] The fibrous activated carbon layer 2 and the nonwoven fabric layer 3 may be laminated in the following ways: they are integrated with an adhesive; they are integrated by a binder component contained in one of the layers, specifically a heat-fusible fiber or a thermoplastic resin, which fuses them together; or they are integrated with the fibrous activated carbon layer 2 by a needle punching method, a water punching method, or the like, without using an adhesive or binder component, by entangling the fibers constituting the nonwoven fabric layer 3 and the fibrous activated carbon constituting the fibrous activated carbon layer 2 on the surface portions of the nonwoven fabric layer 3 and the fibrous activated carbon layer 2. In particular, from the viewpoint of ensuring a larger number of air flow paths in the fibrous activated carbon layer 2 to reduce pressure loss in the deodorizing sheet 1, while increasing the content of fibrous activated carbon throughout the deodorizing sheet 1 and more efficiently removing odorous substances such as methyl mercaptan under aeration conditions, it is preferable that the fibers constituting the nonwoven fabric layer 3 and the fibrous activated carbon constituting the fibrous activated carbon layer 2 be entangled on the surface portions of the nonwoven fabric layer 3 and the fibrous activated carbon layer 2, thereby integrating the nonwoven fabric layer 3 and the fibrous activated carbon layer 2.

[0040] The ratio of the thickness of the fibrous activated carbon layer 2 to the thickness of each nonwoven fabric layer 3 in the deodorizing sheet 1 (thickness of the fibrous activated carbon layer 2 / thickness of each nonwoven fabric layer 3) is preferably 20 to 50, more preferably 25 to 40, and even more preferably 30 to 40, from the viewpoints of ensuring more air flow paths in the fibrous activated carbon layer 2 and reducing pressure loss in the deodorizing sheet 1, while increasing the content of fibrous activated carbon in the entire deodorizing sheet 1 and more efficiently removing odorous substances such as methyl mercaptan under aeration conditions.

[0041] The mass of the deodorizing sheet 1 is not particularly limited, but is preferably 150 to 300 g / m 2 and 180 to 250 g / m 2The thickness of the deodorizing sheet 1 is preferably 1500 to 3000 μm, and more preferably 1700 to 2200 μm. The thickness of the deodorizing sheet 1 is measured at 10 arbitrary points by observing the deodorizing sheet 1 from the cross-sectional direction using a microscope, VHX-5000 manufactured by Keyence Corporation, and the average value of the thicknesses at the 10 points is defined as the thickness of the deodorizing sheet 1. The apparent density of the deodorizing sheet 1 is preferably 0.08 to 0.15 g / cm. 3 0.10 to 0.13 g / cm 3 is preferred. The apparent density of the deodorizing sheet 1 is determined from the mass of the deodorizing sheet 1 and the thickness of the deodorizing sheet 1. The content of activated carbon contained in the deodorizing sheet 1 relative to the mass of the deodorizing sheet 1 is 70 to 95 mass%, and more preferably 75 to 90 mass%. The content of fibrous activated carbon contained in the deodorizing sheet 1 is 70 to 95 mass%, and more preferably 75 to 90 mass%.

[0042] The deodorizing sheet 1 preferably has a pressure loss of 40 Pa or less when measured by the following method. This makes it suitable for use as a filter in an air purifier, etc. Furthermore, from the viewpoint of reducing the pressure loss of the deodorizing sheet 1 while more efficiently removing odorous substances such as methyl mercaptan under ventilation conditions, the pressure loss is preferably 20 to 40 Pa. <Pressure loss test method> In accordance with 3.2 "Pressure loss test" of JIS B 9927:1999 "Appendix (Regulations) Cleanroom Air Filter Media Performance Test Methods," a measurement sample is taken from a deodorizing sheet cut into a circle with a diameter of 110 mm, and the difference in static pressure between the upstream and downstream sides of the activated carbon sheet when air is sucked in at a linear velocity of 0.5 m / s is measured with a differential pressure meter, with the measurement value being valid to the one digit.

[0043] Furthermore, because the deodorizing sheet 1 of the present invention contains fibrous activated carbon, it can efficiently remove odorous substances such as methyl mercaptan under ventilation conditions. An example of a suitable deodorizing performance of the deodorizing sheet 1 of the first embodiment is a methyl mercaptan removal rate measured by the following measurement method of preferably 75% or more, more preferably 90% or more, and even more preferably 95% or more. <Measurement method> FIG. 3 is a schematic diagram illustrating a method for measuring the pressure loss of a deodorizing sheet according to the present invention. First, 1.5 L of a mixture of air components and methyl mercaptan gas at a temperature of 20°C and humidity of 80% RH was sealed in a Tedlar bag 4. This mixture was made so that the methyl mercaptan concentration was 20 ppm. The Tedlar bag and a separately evacuated Tedlar bag 5 were then connected via a glass column 7 filled with deodorizing sheets 1 cut into 15 mm diameter circles. The evacuated Tedlar bag 5 was then placed in a sealable case 8 and sealed. Pump 9 was then used to draw air from case 8 at a constant flow rate, ensuring uniform ventilation across the ventilation surface of deodorizing sheet 1 at a linear velocity of 0.5 m / s. The gas in Tedlar bag 4 was then completely drawn into the evacuated Tedlar bag 5. The concentration of methyl mercaptan in the Tedlar bag 5 after ventilation is measured using a gas detection tube, and the gas removal rate is calculated from the change in concentration before and after ventilation (gas removal rate = (20 ppm - methyl mercaptan concentration in Tedlar bag 5 after ventilation (ppm) / 20 ppm × 100 (%)).

[0044] There are no particular limitations on the method for manufacturing the deodorizing sheet 1 of the first embodiment. For example, the manufacturing method may include the following: a preparation step of preparing a fibrous activated carbon aggregate to serve as the fibrous activated carbon layer 2 and a nonwoven fabric containing fibers other than the fibrous activated carbon to serve as the nonwoven fabric layer 3, and a lamination step of entangling the fibers that make up the prepared nonwoven fabric and the fibrous activated carbon that make up the prepared fibrous activated carbon aggregate to integrate them, thereby laminating the nonwoven fabric layer 3 and the fibrous activated carbon layer 2.

[0045] In the preparation step, the nonwoven fabric to be used as the nonwoven fabric layer 3 (raw nonwoven fabric before integration) has an apparent density of 0.25 g / cm 3 The following is preferable: 0.10 to 0.25 g / cm 3 It is more preferable that the nonwoven fabric has a density of 1000 MPa or less. By using a nonwoven fabric having such a density as the raw material nonwoven fabric, it is possible to further improve the bonding strength due to entanglement between the fibrous activated carbon layer 2 and the nonwoven fabric layer 3. The thickness of the raw material nonwoven fabric is measured by Method A of JIS L 1913:2010, 6.1.1, and the apparent density is calculated from the thickness and mass.

[0046] In the preparation step, the fibrous activated carbon aggregate to be used as the fibrous activated carbon layer 2 may be a fibrous activated carbon aggregate in which fibrous activated carbon is fixed with heat-fusible fiber or pulp, or a cotton-like or felt-like fibrous activated carbon aggregate in which fibrous activated carbon is integrated by being entangled with each other without using a binder component. Among these, a felt-like fibrous activated carbon aggregate in which fibrous activated carbon is integrated by being entangled with each other without using a binder component may be, for example, a fibrous activated carbon aggregate in which fibrous activated carbon is opened and mixed by an airlaid method or a carding method to form a felt.

[0047] In the lamination step, the prepared nonwoven fabric, the fibrous activated carbon aggregate, and the prepared nonwoven fabric are layered in this order, the fibers constituting the nonwoven fabric and the fibrous activated carbon constituting the fibrous activated carbon aggregate are entangled, and the nonwoven fabric and the fibrous activated carbon aggregate are integrated to form a laminate of the nonwoven fabric layer 3, the fibrous activated carbon layer 2, and the nonwoven fabric layer 3. Examples of the entanglement method include a needle punch method and a water punch method, and the needle punch method is preferred.

[0048] In this way, the deodorizing sheet 1 of the first embodiment can be obtained.

[0049] (Second embodiment) Fig. 2 is a schematic cross-sectional view showing a deodorizing sheet 11 of the second embodiment. As shown in Fig. 2, the deodorizing sheet 11 of the present invention comprises a fibrous activated carbon layer 12 containing fibrous activated carbon.

[0050] <Fiber activated carbon> The preferred configuration of the fibrous activated carbon in the deodorizing sheet 11 of the second embodiment is the same as that described above in the description of the deodorizing sheet 1 of the first embodiment. <Fiber activated carbon layer 12> The deodorizing sheet 11 of the second embodiment includes a fibrous activated carbon layer 12.

[0051] The fibrous activated carbon layer 12 contains the above-mentioned fibrous activated carbon, which allows for efficient removal of odorous substances such as methyl mercaptan under aeration conditions.

[0052] The fibrous activated carbon layer 12 may contain components other than the fibrous activated carbon, such as granular or powdered activated carbon, pulp, heat-fusible fibers, and thermoplastic resins as binder components (excluding thermoplastic resins contained in heat-fusible fibers).

[0053] When granular or powdered activated carbon is contained in the fibrous activated carbon layer 12, the content is, for example, 10 to 75 mass%, and preferably 20 to 65 mass%. On the other hand, the fibrous activated carbon layer 12 may be substantially free of granular or powdered activated carbon, and specific content ratios include 5 mass% or less, 3 mass% or less, and 1 mass% or less, with 0 mass% being preferred (no granular or powdered activated carbon).

[0054] The pulp does not fix the filter material by heat fusion itself, but rather fibrillates the filter material and forms a shape by entangling it. Examples of the pulp include cellulosic pulp and acrylic pulp. The freeness of the pulp, measured in accordance with JIS P 8121-2:2012, is preferably 10 to 200 mL. The preferred melting point of the pulp is, for example, 150°C or higher, preferably 200°C or higher. In the present invention, if the pulp does not have a melting point, the softening point is used as the melting point. In the present invention, the melting point is measured using a PerkinElmer DSC-7 differential scanning calorimeter at a heating rate of 20°C / min. When the pulp is contained in the fibrous activated carbon layer 12, the content ratio thereof is, for example, 1 to 25% by mass, preferably 3 to 20% by mass. On the other hand, from the viewpoint of making it easier for the fibrous activated carbon layer 12 to have the apparent density described below, the fibrous activated carbon layer 2 may be substantially free of pulp, and a specific content ratio may be 0.5 mass % or less, with 0 mass % (no pulp) being preferred.

[0055] The heat-fusible fibers, also known as binder fibers, are typically capable of melting by heating and fixing filter media and the like. The heat-fusible component contained in the heat-fusible fibers preferably has a melting point of 80 to 140°C. Specific examples of the heat-fusible component include polyolefin resins such as polyethylene and polypropylene, and polyester resins such as copolymerized polyethylene terephthalate copolymerized with a copolymerization component such as isophthalic acid. Examples of heat-fusible fibers that can be contained in activated carbon molded bodies include fully fused types consisting of a single heat-fusible component, and core-sheath heat-fusible fibers in which the sheath contains a heat-fusible component and the core contains a synthetic resin component whose melting point is preferably 20°C or higher, more preferably 30°C or higher, than that of the sheath. A specific example of the synthetic resin component is polyethylene terephthalate. The glass transition point (Tg) of the heat-fusible component is 20 to 80°C, preferably 50 to 70°C. In the present invention, the glass transition temperature is measured using a differential scanning calorimeter DSC-7 manufactured by PerkinElmer Co., Ltd. at a temperature rise rate of 20°C / min. When the fibrous activated carbon layer 12 contains heat-fusible fibers, the content thereof is, for example, 10 to 70 mass%, and preferably 15 to 45 mass%.

[0056] Examples of the thermoplastic resin used as the binder component (excluding the thermoplastic resin contained in the heat-fusible fibers) include olefin resins (polyethylene, polypropylene, ethylene-vinyl acetate copolymer, ethylene-(meth)acrylic acid copolymer, ethylene-(meth)acrylic acid ester copolymer, etc.), vinyl acetate resins (polyvinyl acetate, vinyl acetate-vinyl chloride copolymer, etc.), polyvinyl alcohol resins (polyvinyl alcohol, ethylene-vinyl alcohol copolymer, etc.), acrylic resins, styrene resins (polystyrene, AS resin, ABS resin, etc.), polyester resins, polyamide resins, thermoplastic polyurethane resins, cellulose derivatives (cellulose ethers such as methyl cellulose, ethyl cellulose, carboxymethyl cellulose, and hydroxyethyl cellulose, and cellulose esters such as cellulose acetate), natural resins (shellac, rosin, etc.), and polysaccharides (sodium alginate, tragacanth gum, gum arabic, pectin, chitosan, and gelatin). When the thermoplastic resin is contained in the fibrous activated carbon layer 12, the content ratio is, for example, 10 to 50% by weight, preferably 10 to 30% by weight. On the other hand, particularly in the first embodiment, in order to ensure more air flow paths in the fibrous activated carbon layer 12 and reduce pressure loss in the deodorizing sheet 1 while increasing the content of fibrous activated carbon in the entire deodorizing sheet 11 and more efficiently removing odorous substances such as methyl mercaptan under ventilation conditions, the fibrous activated carbon layer 12 can be made substantially free of the above-mentioned thermoplastic resin, and specific content percentages include 5% by mass or less, 3% by mass or less, and 1% by mass or less, with 0% by mass (no thermoplastic resin (excluding thermoplastic resin contained in heat-fusible fibers)) being preferred.

[0057] The content of fibrous activated carbon in the fibrous activated carbon layer 12 is preferably 30% by mass or more, more preferably 30 to 90% by mass, and even more preferably 55 to 85% by mass, from the viewpoint of ensuring more air flow paths in the fibrous activated carbon layer 12, reducing pressure loss in the deodorizing sheet 11, while increasing the content of fibrous activated carbon in the entire deodorizing sheet 11 and more efficiently removing odorous substances such as methyl mercaptan under aeration conditions.

[0058] The form of the fibrous activated carbon layer 12 may be a fibrous activated carbon aggregate in which fibrous activated carbon is fixed with heat-fusible fibers or pulp, a cotton-like fibrous activated carbon aggregate regardless of heat-fusible fibers or pulp, or a fibrous activated carbon aggregate in which fibrous activated carbon is made into a felt-like form. Examples of the fibrous activated carbon aggregate in which fibrous activated carbon is fixed with heat-fusible fibers or pulp include needle-punched nonwoven fabrics and wet-laid paper-making nonwoven fabrics.

[0059] Among these, it is preferable that the fibrous activated carbon layer 12 contains fibrous activated carbon and heat-fusible fibers, and that the fibrous activated carbon and the heat-fusible fibers are integrated by entanglement without melting the heat-fusible fibers to form a fibrous activated carbon aggregate. That is, by intentionally incorporating the heat-fusible fibers into the fibrous activated carbon layer 12 without melting them, more air flow paths can be secured in the fibrous activated carbon layer 12, and the pressure loss of the deodorizing sheet 11 can be further reduced. To achieve this, in the manufacture of the deodorizing sheet 11, heat treatment at a temperature above (the melting point Tm of the heat-fusible component of the heat-fusible component - (minus) 20°C) (for example, if the melting point is 110°C, 110-20 = 90°C or higher) can be avoided, and the fibrous activated carbon and the heat-fusible component can be entangled and integrated using a needle punch method, water punch method, etc. More preferably, the fibrous activated carbon and the heat-fusible component can be entangled and integrated using a needle punch method, water punch method, etc., and then the heat treatment can be performed at a temperature above the glass transition point of the heat-fusible component but below (the melting point Tm of the heat-fusible component - 20°C) (for example, if the melting point is 110°C, 110-20 = less than 90°C).

[0060] The mass of the fibrous activated carbon layer 12 is set to 20 g / m from the viewpoint of more efficiently removing odorous substances such as methyl mercaptan under aeration conditions. 2 More than 50g / m 2 Although there is no particular upper limit, from the viewpoint of reducing the pressure loss of the deodorizing sheet 11 while increasing the content of fibrous activated carbon in the entire deodorizing sheet 11 and more efficiently removing odorous substances such as methyl mercaptan under ventilation conditions, it is preferable that the upper limit be 100 g / m 2 The following is preferred:

[0061] The thickness of the fibrous activated carbon layer 12 is preferably 200 μm to 1000 μm, and more preferably 500 μm to 1000 μm, from the viewpoint of reducing the pressure loss of the deodorizing sheet 11 while increasing the content of fibrous activated carbon throughout the deodorizing sheet 11 and more efficiently removing odorous substances such as methyl mercaptan under aeration conditions. The thickness of the fibrous activated carbon layer 12 is measured at 10 arbitrary points by observing the deodorizing sheet 11 from the cross-sectional direction using a microscope, VHX-5000 manufactured by Keyence Corporation, and the average value of the thicknesses at the 10 points is defined as the thickness of the fibrous activated carbon layer 12. The apparent density of the fibrous activated carbon layer 12 is 0.15 g / cm. 3 The following are listed: 0.11 g / cm 3 The following are preferred: 0.10 g / cm 3 The lower limit is not particularly limited, but for example, 0.05 g / cm 3 The above are listed, and 0.08g / cm 3 The apparent density is determined from the mass of the fibrous activated carbon layer 12 and the thickness of the fibrous activated carbon layer 12.

[0062] The pressure loss of the deodorizing sheet 11, as measured by the following method, is preferably 30 Pa or less, more preferably 25 Pa or less, and even more preferably 10 Pa or less. This makes it suitable for use as a filter for an air purifier, etc. Furthermore, from the viewpoint of reducing the pressure loss of the deodorizing sheet 1 while more efficiently removing odorous substances such as methyl mercaptan under ventilation conditions, the pressure loss is preferably 5 to 10 Pa. <Pressure loss test method> In accordance with 3.2 "Pressure loss test" of JIS B 9927:1999 "Appendix (Regulations) Cleanroom Air Filter Media Performance Test Methods," the activated carbon sheet is cut into a circle with a diameter of 110 mm and used as the measurement sample. The difference in static pressure between the upstream and downstream sides of the activated carbon sheet when air is sucked in at a linear velocity of 0.5 m / s is measured with a differential pressure meter, and the measurement value is considered to be valid up to the one digit.

[0063] Furthermore, because the deodorizing sheet 11 of the present invention contains fibrous activated carbon, it can efficiently remove odorous substances such as methyl mercaptan under aeration conditions. An example of a suitable deodorizing performance of the deodorizing sheet 11 of the first embodiment is a methyl mercaptan removal rate of preferably 50% or more, and more preferably 60% or more, as measured by the following measurement method. <Measurement method> FIG. 3 is a schematic diagram illustrating a method for measuring the pressure loss of a deodorizing sheet according to the present invention. First, 1.5 L of a mixture of air components and methyl mercaptan gas at a temperature of 20°C and humidity of 80% RH was sealed in a Tedlar bag 4. This mixture was made so that the methyl mercaptan concentration was 20 ppm. The Tedlar bag and a separately evacuated Tedlar bag 5 were then connected via a glass column 7 filled with deodorizing sheets 11 cut into 15 mm diameter circles. The evacuated Tedlar bag 5 was then placed in a sealable case 8 and sealed. Pump 9 was then used to draw air from case 8 at a constant volume so that the air was evenly ventilated across the ventilation surface of deodorizing sheet 11 at a linear velocity of 0.5 m / s. The gas in Tedlar bag 4 was then completely drawn into the evacuated Tedlar bag 5. The concentration of methyl mercaptan in the Tedlar bag 5 after ventilation is measured using a gas detection tube, and the gas removal rate is calculated from the change in concentration before and after ventilation (gas removal rate = (20 ppm - methyl mercaptan concentration in Tedlar bag 5 after ventilation (ppm) / 20 ppm × 100 (%)).

[0064] The method for manufacturing the deodorizing sheet 11 of the second embodiment is not particularly limited. For example, the following manufacturing method may be used. Specifically, the manufacturing method may include a step of preparing fibrous activated carbon and heat-fusible fibers, and a step of entangling the fibrous activated carbon and the heat-fusible fibers to integrate them, without performing a heat treatment at a temperature equal to or higher than the melting point (Tm - (minus) 20°C) of the heat-fusible component of the heat-fusible fibers (for example, if the melting point is 110°C, then 110 - 20 = 90°C or higher). This further reduces the pressure loss of the deodorizing sheet 11. It is also preferable to include a step of performing a heat treatment on the sheet in which the fibrous activated carbon and the heat-fusible fibers have been integrated by the entanglement, at a temperature equal to or higher than the glass transition point of the heat-fusible component of the heat-fusible fibers but lower than the melting point (Tm - 20°C) of the heat-fusible component (for example, if the melting point is 110°C, then 110 - 20 = less than 90°C). By performing such heat treatment, the fibrous activated carbon and the heat-fusible fibers are entangled and integrated together and then heat-set without the heat-fusible fibers melting, thereby further improving the strength of the deodorizing sheet 11 and reducing pressure loss.

[0065] <Uses of the deodorizing sheet of the present invention> The uses of the deodorizing sheet of the present invention are not particularly limited. For example, it can be used as a filter for an air purifier or as a sanitary product used in medical settings, homes, etc. In addition, the deodorizing sheet of the present invention can be subjected to known processing, such as pleating. In addition, the deodorizing sheet of the present invention can be used in combination with other functional sheets, such as other deodorizing sheets or absorbent sheets. [Example]

[0066] The present invention will be described in detail below with reference to examples and comparative examples, but the present invention is not limited to these examples.

[0067] 1. Materials used in the examples (1) Fibrous activated carbon contained in fibrous activated carbon layer 2 or 12 Fibrous activated carbon A (manufactured by Ador Co., Ltd., product name A-10, coal pitch-based, fiber diameter 17 μm, specific surface area 1300 m 2 / g, tensile strength 250N / mm 2 ) Fibrous activated carbon B (manufactured by Ador Co., Ltd., product name A-7, coal pitch type, fiber diameter 17 μm, specific surface area 850 m 2 / g, tensile strength 330N / mm 2 ) Fibrous activated carbon C (manufactured by Ador Co., Ltd., product name A-15, coal pitch type, fiber diameter 16 μm, specific surface area 1700 m 2 / g, tensile strength 220N / mm 2 )

[0068] (2) Nonwoven fabric contained in nonwoven fabric layer 3 Unisel Corporation product name: Unisel (registered trademark) BT-0403W2 (weight 20g / m 2 , thickness 0.09 mm, apparent density 0.22 g / cm 3, MD direction tensile strength 50N / 5cm, TD direction tensile strength 50N / 5cm, polyethylene terephthalate long fiber and polypropylene fiber containing, tow-opened polyethylene terephthalate long fiber web, long fiber nonwoven fabric without embossing

[0069] (3) Heat-fusible fibers contained in the fibrous activated carbon layer 12 Huvis LMF 2 DENIER (a core-sheath type heat-bondable fiber with a polyethylene terephthalate core and a polyester sheath containing isophthalic acid and terephthalic acid as polybasic acid components; the sheath, which is the heat-bondable component, has a melting point of 110°C, a glass transition point of 65°C, a fineness of 2.2 dtex, and a fiber length of 51 mm)

[0070] 2. Examples Example 1 The above-mentioned fibrous activated carbon A and two sheets of nonwoven fabric to be included in the nonwoven fabric layer 3 were prepared.

[0071] The mass of the fibrous activated carbon A used for the fibrous activated carbon layer 2 is 190 g / m 2 A carding machine was used to open and mix the fibrous activated carbon A to prepare a felt-like fibrous activated carbon aggregate. Next, a nonwoven fabric, the felt-like fibrous activated carbon aggregate, and the nonwoven fabric were layered in this order, and needle-punched from one side of the nonwoven fabric so that the thickness of the deodorizing sheet 1 was 2000 μm. The nonwoven fabric and the fibrous activated carbon aggregate were integrated, resulting in a deodorizing sheet 1 of Example 1, which is the first embodiment, as shown in FIG. 1 . In the resulting deodorizing sheet 1, the fibrous activated carbon layer 2 had a thickness of 1892 μm, the thickness of each nonwoven fabric layer 3 was 54 μm, and the thickness of the deodorizing sheet 1 was 2000 μm. Furthermore, the fibers constituting the nonwoven fabric layer 3 and the fibrous activated carbon constituting the fibrous activated carbon layer 2 were entangled on the surface portions of the nonwoven fabric layer 3 and the fibrous activated carbon layer 2.

[0072] <Example 2> The above-mentioned fibrous activated carbon A and two sheets of nonwoven fabric to be included in the nonwoven fabric layer 3 were prepared.

[0073] The mass of the fibrous activated carbon A used for the fibrous activated carbon layer 2 is 160 g / m 2 A carding machine was used to open and mix the fibrous activated carbon A to prepare a felt-like fibrous activated carbon aggregate. Next, the nonwoven fabric, the felt-like fibrous activated carbon aggregate, and the nonwoven fabric were layered in this order, and needle-punched from one side of the nonwoven fabric to integrate the nonwoven fabric and the fibrous activated carbon aggregate so that the thickness of the deodorizing sheet 1 was 1900 μm, thereby obtaining the deodorizing sheet 1 of Example 2, which is the first embodiment, as shown in FIG. 1 . In the obtained deodorizing sheet 1, the fibrous activated carbon layer 2 had a thickness of 1786 μm, the thickness of each nonwoven fabric layer 3 was 57 μm, and the thickness of the deodorizing sheet 1 was 1900 μm. Furthermore, the fibers constituting the nonwoven fabric layer 3 and the fibrous activated carbon constituting the fibrous activated carbon layer 2 were entangled on the surface portions of the nonwoven fabric layer 3 and the fibrous activated carbon layer 2.

[0074] Example 3 The above-mentioned fibrous activated carbon B and two sheets of nonwoven fabric to be included in the nonwoven fabric layer 3 were prepared.

[0075] The mass of the fibrous activated carbon B used for the fibrous activated carbon layer 2 is 190 g / m 2 A carding machine was used to open and mix the fibrous activated carbon B to prepare a felt-like fibrous activated carbon aggregate. Next, the nonwoven fabric, the felt-like fibrous activated carbon aggregate, and the nonwoven fabric were layered in this order, and needle-punched from one side of the nonwoven fabric so that the thickness of the deodorizing sheet 1 was 2000 μm. The nonwoven fabric and the fibrous activated carbon aggregate were integrated to obtain the deodorizing sheet 1 of Example 3, which is the first embodiment, as shown in FIG. 1 . In the obtained deodorizing sheet 1, the thickness of the fibrous activated carbon layer 2 was 1894 μm, the thickness of each nonwoven fabric layer 3 was 53 μm, and the thickness of the deodorizing sheet 1 was 2000 μm. Furthermore, the fibers constituting the nonwoven fabric layer 3 and the fibrous activated carbon constituting the fibrous activated carbon layer 2 were entangled on the surface portions of the nonwoven fabric layer 3 and the fibrous activated carbon layer 2.

[0076] Example 4 The above-mentioned fibrous activated carbon B and the heat-fusible fibers contained in the fibrous activated carbon layer 12 were prepared.

[0077] The prepared fibrous activated carbon B and heat-fusible fibers were opened and mixed in a carding machine so that the mass ratio of fibrous activated carbon B to heat-fusible fibers (mass of fibrous activated carbon B / mass of heat-fusible fibers) was 37 / 63, to produce a thin fibrous activated carbon aggregate. Multiple sheets of the fibrous activated carbon aggregate were stacked and then needle-punched to entangle the fibrous activated carbon B and the heat-fusible fibers. The sheets were then passed through a heated roller at a temperature of 105°C to melt the heat-fusible components of the heat-fusible fibers, resulting in a deodorizing sheet 11 of Example 4, which is a second embodiment, as shown in FIG. 2. The thickness of the resulting deodorizing sheet 11 was 220 μm. Furthermore, in the deodorizing sheet 11, the heat-fusible fibers were present in a molten state.

[0078] <Example 5> The above-mentioned fibrous activated carbon B and the heat-fusible fibers contained in the fibrous activated carbon layer 12 were prepared.

[0079] The prepared fibrous activated carbon B and heat-fusible fibers were opened and mixed in a carding machine so that the mass ratio of fibrous activated carbon B to heat-fusible fibers (mass of fibrous activated carbon B / mass of heat-fusible fibers) was 37 / 63, producing a thin fibrous activated carbon aggregate. Multiple sheets of the fibrous activated carbon aggregate were stacked and then needle-punched to entangle the fibrous activated carbon B and the heat-fusible fibers, followed by heat treatment in an oven at 70°C for heat setting, to obtain a deodorizing sheet 11 of Example 5, which is a second embodiment, as shown in FIG. 2. The thickness of the resulting deodorizing sheet 11 was 350 μm. Furthermore, in the deodorizing sheet 11, the heat-fusible fibers were present in an unmelted state.

[0080] Example 6 The above-mentioned fibrous activated carbon A and the heat-fusible fibers contained in the fibrous activated carbon layer 12 were prepared.

[0081] The prepared fibrous activated carbon A and heat-fusible fibers were opened and mixed in a carding machine so that the mass ratio of the fibrous activated carbon A to the heat-fusible fibers (mass of fibrous activated carbon A / mass of heat-fusible fibers) was 60 / 40, producing a thin fibrous activated carbon aggregate. Multiple sheets of the fibrous activated carbon aggregate were stacked and then needle-punched to entangle the fibrous activated carbon A and the heat-fusible fibers. The sheets were then passed through a heated roller at a temperature of 105°C to melt the heat-fusible components of the heat-fusible fibers, resulting in a deodorizing sheet 11 of Example 6, which is a second embodiment, as shown in FIG. 2. The thickness of the resulting deodorizing sheet 11 was 550 μm. Furthermore, in the deodorizing sheet 11, the heat-fusible fibers were present in a molten state.

[0082] Example 7 The above-mentioned fibrous activated carbon A and the heat-fusible fibers contained in the fibrous activated carbon layer 12 were prepared.

[0083] The prepared fibrous activated carbon A and heat-fusible fibers were opened and mixed in a carding machine so that the mass ratio of the fibrous activated carbon A to the heat-fusible fibers (mass of fibrous activated carbon A / mass of heat-fusible fibers) was 60 / 40, producing a thin fibrous activated carbon aggregate. Multiple sheets of the fibrous activated carbon aggregate were stacked and then needle-punched to entangle the fibrous activated carbon A and the heat-fusible fibers. The sheets were then heat-set by heat treatment in an oven at 70°C, yielding a deodorizing sheet 11 of Example 7, which is the second embodiment, as shown in FIG. 2. The thickness of the resulting deodorizing sheet 11 was 700 μm. Furthermore, in the deodorizing sheet 11, the heat-fusible fibers were present in an unmelted state.

[0084] Example 8 The above-mentioned fibrous activated carbon C and the heat-fusible fibers contained in the fibrous activated carbon layer 12 were prepared.

[0085] The prepared fibrous activated carbon C and heat-fusible fibers were opened and mixed in a carding machine so that the mass ratio of the fibrous activated carbon C to the heat-fusible fibers (mass of fibrous activated carbon C / mass of heat-fusible fibers) was 75 / 25, to produce a thin fibrous activated carbon aggregate. Multiple sheets of the fibrous activated carbon aggregate were stacked and then needle-punched to entangle the fibrous activated carbon C and the heat-fusible fibers. The sheets were then passed through a heated roller at a temperature of 105°C to melt the heat-fusible components of the heat-fusible fibers, resulting in a deodorizing sheet 11 of Example 8, a second embodiment, as shown in FIG. 2. The thickness of the resulting deodorizing sheet 11 was 520 μm. Furthermore, in the deodorizing sheet 11, the heat-fusible fibers were present in a molten state.

[0086] 3. Evaluation Method (1) Specific surface area, fiber diameter, and tensile strength of fibrous activated carbon The evaluation was carried out by the method described above.

[0087] (2) Melting point and glass transition point of the heat-fusible component of the heat-fusible fiber The evaluation was carried out by the method described above.

[0088] (3) Thickness of the fibrous activated carbon layer, nonwoven fabric layer, and deodorizing sheet in the deodorizing sheet The evaluation was carried out by the method described above.

[0089] (4) Pressure loss of deodorizing sheets In accordance with 3.2 "Pressure loss test" of JIS B 9927:1999 "Appendix (Regulations) Cleanroom Air Filter Media Performance Test Methods," the activated carbon sheet was cut into a circle with a diameter of 110 mm and used as a measurement sample. The difference in static pressure between the upstream and downstream sides of the activated carbon sheet when air was sucked in at a linear velocity of 0.5 m / s was measured with a differential pressure meter, and the measurement value was considered to be valid up to the one digit.

[0090] (5) Removal rate of methyl mercaptan <Measurement method> FIG. 3 is a schematic diagram illustrating a method for measuring the pressure loss of a deodorizing sheet according to the present invention. First, 1.5 L of a mixture of air components and methyl mercaptan gas at a temperature of 20°C and a humidity of 80% RH was sealed in a Tedlar bag 4. The mixture was made so that the methyl mercaptan concentration was 20 ppm. The Tedlar bag and a separately evacuated Tedlar bag 5 were then connected via a glass column 7 filled with deodorizing sheets cut into 15 mm diameter circles. The evacuated Tedlar bag 5 was then placed in a sealable case 8 and sealed. Pump 9 was used to draw air from case 8 at a constant flow rate so that the air was evenly ventilated across the ventilation surface of the deodorizing sheet at a linear velocity of 0.5 m / s. The gas in the Tedlar bag 4 was then completely circulated into the evacuated Tedlar bag 5. The concentration of methyl mercaptan in the Tedlar bag 5 into which the gas was passed was measured using a gas detection tube, and the gas removal rate was calculated from the change in concentration before and after ventilation (gas removal rate = (20 ppm - methyl mercaptan concentration in the Tedlar bag 5 after ventilation (ppm) / 20 ppm × 100 (%)). Products with a removal rate of 20% or more were deemed to have passed the test, as they were capable of efficiently removing odorous substances such as methyl mercaptan under aeration conditions.

[0091] The evaluation results of each example are shown in Table 1.

[0092] [Table 1]

[0093] As is clear from Table 1, the deodorizing sheets of Examples 1 to 8 were able to efficiently remove odorous substances such as methyl mercaptan under ventilation conditions.

[0094] In particular, the sheets of Examples 1 to 3 were formed by laminating, in this order, a nonwoven fabric layer containing fibers other than fibrous activated carbon, a fibrous activated carbon layer containing the fibrous activated carbon, and a nonwoven fabric layer containing fibers other than fibrous activated carbon. This reduced the pressure loss of the deodorizing sheet while increasing the content of fibrous activated carbon throughout the deodorizing sheet, enabling more efficient removal of odorous substances such as methyl mercaptan under ventilation conditions.

[0095] Among them, the deodorizing sheets of Examples 1 and 2 have a specific surface area of ​​1200 to 1400 m 2 / g and tensile strength is 240~280N / m 2 Therefore, it was possible to efficiently remove odorous substances such as methyl mercaptan under aeration conditions, while more easily suppressing an increase in pressure loss due to deformation of the fibrous activated carbon under aeration conditions.

[0096] Furthermore, when Examples 4 and 5 and Examples 6 and 7 are compared, it is found that in Examples 5 and 7, the fibrous activated carbon layer contains fibrous activated carbon and heat-fusible fibers, and the fibrous activated carbon and the heat-fusible fibers are integrated by entanglement without the heat-fusible fibers melting. Therefore, compared to Examples 6 and 8, more air flow paths are secured in the fibrous activated carbon layer 12, which further reduces the pressure loss of the deodorizing sheet 11, and also enables more efficient removal of odorous substances such as methyl mercaptan under ventilation conditions. [Explanation of symbols]

[0097] 1, 11: Deodorizing sheet 2,12: Fibrous activated carbon layer 3: Non-woven layer 4, 5: Tedlar bag 6: Glass column 7: Case 8: Pump

Claims

1. A deodorizing sheet comprising a fibrous activated carbon layer containing fibrous activated carbon and heat-fusible fibers, The melting point of the heat-fusible component contained in the heat-fusible fiber is 80 to 140°C, the fibrous activated carbon and the heat-fusible fibers are integrated by entanglement without the heat-fusible fibers being melted; The content of the fibrous activated carbon in the fibrous activated carbon layer is 37% by mass or more, The deodorizing sheet, wherein the mass of the fibrous activated carbon layer is 30 g / m 2 or more.

2. 2. The deodorizing sheet according to claim 1, wherein the heat-fusible fiber is a core-sheath type heat-fusible fiber having the heat-fusible component in the sheath and a synthetic resin component in the core, the melting point of which is at least 20°C higher than the melting point of the sheath.

3. 3. The deodorizing sheet according to claim 1, wherein a nonwoven fabric layer containing fibers other than fibrous activated carbon, a fibrous activated carbon layer containing the fibrous activated carbon and the heat-fusible fibers, and a nonwoven fabric layer containing fibers other than the fibrous activated carbon are laminated in this order.

4. 4. The deodorizing sheet according to claim 3, wherein the content of the fibrous activated carbon in the fibrous activated carbon layer is 90% by mass or more.

5. 5. The deodorizing sheet according to claim 3, wherein the ratio of the mass of the activated carbon contained in the deodorizing sheet to the mass of the deodorizing sheet is 70 to 95 mass %.

6. 6. The deodorizing sheet according to claim 3, wherein the fibers constituting the nonwoven fabric layer and the fibrous activated carbon constituting the fibrous activated carbon layer are entangled at the surface portions of the nonwoven fabric layer and the fibrous activated carbon layer, thereby integrating the nonwoven fabric layer and the fibrous activated carbon layer.

7. The deodorizing sheet according to any one of claims 3 to 6, wherein the nonwoven fabric layer comprises a long-fiber nonwoven fabric and is not embossed.

8. The deodorizing sheet according to any one of claims 3 to 7, wherein the ratio of the thickness of the fibrous activated carbon layer to the thickness per layer of the nonwoven fabric layer (thickness of the fibrous activated carbon layer / thickness per layer of the nonwoven fabric layer) is 20 to 50.

9. The apparent density of the fibrous activated carbon layer is 0.11 g / cm ３ The sheet according to any one of claims 1 to 8, wherein:

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