JP2022189491A - deodorizing sheet - Google Patents

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

The present invention relates to a deodorizing sheet.

BACKGROUND ART There is an increasing demand for deodorizing sanitary products for medical sites and households to eliminate unpleasant odors. The main odors that contaminate indoor air are human body odors, toilet odors, putrid odors, etc. The main components of these odors are hydrogen sulfide, methyl mercaptan, ammonia, and trimethylamine, which are generated when organic matter is decomposed by microorganisms. be.

Adsorbent sheets are known which are made by laminating an activated carbon sheet and a breathable reinforcing sheet, wherein an adsorbent for acidic substances is attached to the activated carbon sheet and an adsorbent for alkaline substances is attached to the breathable sheet. (See Patent Document 1, for example).

JP-A-6-39238

However, according to the study of the present inventors, when the adsorptive sheet disclosed in Patent Document 1 is used for a filter of an air purifier or the like, an odor remains at the initial stage of operation of a fan or the like of the air purifier. There was a problem. Accordingly, the main object of the present invention is to provide a deodorizing sheet which solves the above problems and can efficiently remove malodorous substances such as methyl mercaptan under ventilation conditions.

The present inventors have made intensive studies to solve the above problems, and have found that it is effective to use fibrous activated carbon as a filter material constituting the deodorizing sheet. The present invention is an invention completed through further studies.

That is, the present invention provides inventions in the following aspects.
Section 1. A deodorizing sheet comprising a fibrous activated carbon layer containing fibrous activated carbon.
Section 2. Item 1. The deodorizing sheet according to Item 1, wherein 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 are laminated in this order.
Item 3. Item 3. The deodorizing sheet according to Item 2, wherein the fibrous activated carbon content in the fibrous activated carbon layer is 90% by mass or more.
Section 4. 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% by mass.
Item 5. The fibers constituting the nonwoven fabric layer and the fibrous activated carbon constituting the fibrous activated carbon layer are entangled at the surface portion of the nonwoven fabric layer and the surface portion of the fibrous activated carbon layer, whereby the nonwoven layer and the fibrous activated carbon are entangled. Item 5. The deodorant sheet according to any one of Items 2 to 4, wherein the deodorant sheet is integrated with the layer.
Item 6. 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. Items 2-, wherein the ratio of the thickness of the fibrous activated carbon layer to the thickness per layer of the non-woven fabric layer (thickness of the fibrous activated carbon layer/thickness per non-woven fabric layer) is 20 to 50. 7. The deodorizing sheet according to any one of 6.
Item 8. The sheet according to any one of claims 1 to 7, wherein the fibrous activated carbon layer has an apparent density of 0.11 or less.

According to the deodorant sheet of the present invention, since it contains fibrous activated carbon, odorants such as methyl mercaptan can be efficiently removed under ventilation conditions.

BRIEF DESCRIPTION OF THE DRAWINGS It is a cross-sectional schematic diagram which shows the deodorizing sheet of 1st Embodiment. It is a cross-sectional schematic diagram which shows the deodorizing sheet of 2nd Embodiment. It is a schematic diagram explaining the measuring method of the pressure loss of the deodorizing sheet in this invention.

The deodorizing sheet of the present invention includes a fibrous activated carbon layer containing fibrous activated carbon. Preferred embodiments of the present invention are described below. However, the following embodiments are merely examples. The present invention is by no means limited to the following embodiments.

(First embodiment)
FIG. 1 is a cross-sectional schematic diagram showing the deodorizing sheet of the first embodiment. As shown in FIG. 1, the deodorizing sheet 1 of the present invention includes 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. , are stacked in this order. By adopting such a configuration, the pressure loss of the deodorizing sheet 1 can be reduced, and the content of the fibrous activated carbon in the entire deodorizing sheet 1 can be increased to more efficiently remove malodorous substances such as methyl mercaptan under ventilation conditions. can be done effectively.

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 at the surface portion of the nonwoven fabric layer 3 and the surface portion of the fibrous activated carbon layer 2 to form a nonwoven fabric. The layer 3 and the fibrous activated carbon layer 2 can be integrated. The form of entanglement includes entanglement by a needle punch method or a water punch method, preferably entanglement by a needle punch method. Materials and layers constituting the deodorizing sheet 1 of the first embodiment will be described in detail below.

<Fibrous Activated Carbon>
In the present invention, the types of fibrous activated carbon include, for example, polyacrylonitrile-based, rayon-based, phenolic resin-based, coal-pitch-based, and petroleum-pitch-based fibers that are infusibilized and, if desired, carbonized, followed by steam and dioxide. Any fibrous activated carbon produced by activating by being held at a predetermined temperature for a predetermined time in an atmosphere containing carbon can be employed. Among these, coal pitch-based, petroleum pitch-based, and polyacrylonitrile-based fibrous activated carbons are preferred. One type of fibrous activated carbon may be used alone, or two or more types may be used in combination.

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

In the present invention, the specific surface area of fibrous activated carbon is not particularly limited, but is preferably about 500 to 2100 m ² /g. In particular, from the viewpoint of efficiently removing odorous substances such as methyl mercaptan under aeration conditions and making it easier to suppress the increase in pressure loss accompanying the deformation of the fibrous activated carbon under aeration conditions, fibrous activated carbon is used. The specific surface area is preferably 1200-1850 m ² /g, more preferably 1200-1400 ² /g. The specific surface area of fibrous activated carbon is a value determined by the BET method (one-point method) described in JIS K1477:2007.

In the present invention, the tensile strength of the fibrous activated carbon is not particularly limited, but may be about 150 to 400 N/mm ² . In particular, from the viewpoint of efficiently removing odorous substances such as methyl mercaptan under aeration conditions and making it easier to suppress the increase in pressure loss accompanying the deformation of the fibrous activated carbon under aeration conditions, fibrous activated carbon is used. The tensile strength is preferably 240-280 N/mm ² . The tensile strength of fibrous activated carbon is a value determined by the method described in JIS K1477:2007.

The fibrous activated carbon can be impregnated with an agent for removing specific odorants. Examples of such agents include fibrous activated carbon, inorganic acids, inorganic salts, and acidic organic compounds, specifically ferrous chloride, ferrous sulfate, to remove alkaline odorants such as ammonia. One or more kinds of sulfuric acid, phosphoric acid, citric acid, malic acid, etc. may be impregnated. In addition, as the agent, for example, fibrous activated carbon, inorganic bases, inorganic acids, and basic organic compounds, specifically potassium carbonate and sodium carbonate, are used to remove acidic odorants such as hydrogen sulfide. , calcium carbonate, potassium permanganate, or the like. On the other hand, when the agent for removing the specific odorant is impregnated, the removal performance of the specific odorant is improved, but due to the effect of the pore clogging of the fibrous activated carbon due to the impregnation of the agent, the In some cases, the removal performance of odorants other than specific odorants is lowered. Therefore, for example, from the viewpoint of further improving the balance of removal performance under ventilation conditions for alkaline odorants and acid odorants, the amount of the chemical attached to the fibrous activated carbon for removing the above-mentioned specific odorants is is preferably 5% by mass or less, more preferably 3% by mass or less, still more preferably 1% by mass or less, and particularly preferably 0% by mass (does not contain the above drug).

<Fibrous activated carbon layer 2>
A deodorizing sheet 1 of the first embodiment includes a fibrous activated carbon layer 2 .

The fibrous activated carbon layer 2 contains the fibrous activated carbon described above. This makes it possible to efficiently remove odorous substances such as methyl mercaptan under ventilation conditions.

The fibrous activated carbon layer 2 can contain components other than the fibrous activated carbon. The other components include granular or powdered activated carbon, pulp, heat-fusible fibers, and thermoplastic resins as binder components (excluding thermoplastic resins contained in heat-fusible fibers) (hereinafter referred to as The pulp, the heat-fusible fiber, and the thermoplastic resin as the binder component may be collectively referred to as the "binder component."), and the like.

When the fibrous activated carbon layer 2 contains granular or powdered activated carbon, the content is, for example, 10 to 75% by mass, preferably 20 to 65% by mass. On the other hand, granular or powdery activated carbon can be substantially not contained in the fibrous activated carbon layer 2, and specific content ratios are 5% by mass or less, 3% by mass or less, and 1% by mass or less. and preferably 0% by mass (not containing granular or powdered activated carbon).

The above-mentioned pulp does not fix the filter material by heat-sealing itself, but is fibrillated to entangle the filter material and shape it. Examples of the pulp include cellulose pulp and acrylic pulp. The freeness of the pulp is preferably 10 to 200 mL as measured according to JIS P 8121-2:2012. A preferred pulp melting point is, for example, a melting point of 150° C. or higher, preferably 200° C. or higher. In addition, in this invention, when it does not have a melting point, let a softening point be a melting point. In the present invention, the melting point is measured using a differential scanning calorimeter DSC-7 manufactured by PerkinElmer at a heating rate of 20° C./min. When the fibrous activated carbon layer 2 contains pulp, the content is, for example, 1 to 25% by mass, preferably 3 to 20% by mass. On the other hand, from the viewpoint of facilitating the apparent density of the fibrous activated carbon layer 2 to be described later, the fibrous activated carbon layer 2 can be substantially free of pulp. 0.5 mass % or less is mentioned, and 0 mass % (not containing pulp) is preferable.

The above heat-fusible fibers are also called binder fibers, and usually can be melted by heating to fix a filter medium or the like. The heat-fusible component contained in the heat-fusible fiber 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 obtained by copolymerizing a copolymer component such as isophthalic acid. In addition, the heat-fusible fibers that can be included in the fibrous activated carbon layer 2 are all-melting type consisting of only a single heat-fusible component, or a heat-fusible component in the sheath and a melting point in the core. A core-sheath type heat-fusible fiber in which a synthetic resin component having a melting point higher than that of the sheath by preferably 20° C. or more, more preferably 30° C. or more, is included. A specific example of the synthetic resin component arranged in the sheath is polyethylene terephthalate.

The fineness of the heat-fusible fiber is 1 to 20 dtex. Further, the fiber length of the heat-fusible fiber is 10 to 70 mm.

When the fibrous activated carbon layer 2 contains heat-fusible fibers, the content is, for example, 10 to 50% by mass, preferably 10 to 30% by mass. On the other hand, particularly in the first embodiment, the content of fibrous activated carbon in the entire deodorizing sheet 1 is increased while securing more air flow paths in the fibrous activated carbon layer 2 and reducing the pressure loss of the deodorizing sheet 1. From the viewpoint of more efficiently removing odorous substances such as methyl mercaptan under conditions of higher aeration, the fibrous activated carbon layer 2 can be substantially free of heat-fusible fibers. Examples of the content ratio include 5% by mass or less, 3% by mass or less, and 1% by mass or less, and 0% by mass (not containing heat-fusible fibers) is preferable.

The thermoplastic resin (excluding the thermoplastic resin contained in the heat-fusible fiber) as the binder component includes olefin resins (polyethylene, polypropylene, ethylene-vinyl acetate copolymer, ethylene-(meth)acrylic acid copolymers, ethylene-(meth)acrylic acid ester copolymers, etc.), vinyl acetate resins (polyvinyl acetate, vinyl acetate-vinyl chloride copolymers, etc.), polyvinyl alcohol resins (polyvinyl alcohol, ethylene-vinyl alcohol copolymers, etc.), acrylic resins, styrene resins (polystyrene, AS resin, ABS resin, etc.), polyester resins, polyamide resins, thermoplastic polyurethane resins, cellulose derivatives (methylcellulose, ethylcellulose, carboxymethylcellulose, hydroxyethylcellulose, etc.) cellulose ethers, cellulose esters such as cellulose acetate), natural resins (shellac, rosin, etc.), polysaccharides (sodium alginate, tragacanth gum, gum arabic, pectin, chitosan, gelatin). When the fibrous activated carbon layer 2 contains the thermoplastic resin, the content is, for example, 10 to 50% by mass, preferably 10 to 30% by mass. On the other hand, particularly in the first embodiment, the content of fibrous activated carbon in the entire deodorizing sheet 1 is increased while securing more air flow paths in the fibrous activated carbon layer 2 and reducing the pressure loss of the deodorizing sheet 1. From the viewpoint of more efficiently removing odorous substances such as methyl mercaptan under conditions of higher aeration, the fibrous activated carbon layer 2 can be substantially free of the thermoplastic resin. The content ratio includes 5% by mass or less, 3% by mass or less, and 1% by mass or less, and does not contain 0% by mass (thermoplastic resin (excluding the thermoplastic resin contained in the heat-fusible fiber). ) is preferred.

The content ratio of the fibrous activated carbon in the fibrous activated carbon layer 2 is such that more air flow paths are secured in the fibrous activated carbon layer 2 and the pressure loss of the deodorizing sheet 1 is reduced. From the viewpoint of more efficiently removing odorous substances such as methyl mercaptan under ventilation conditions by increasing the content of the activated carbon, it is preferably 80% by mass or more, more preferably 90% by mass or more, and further preferably 95% by mass or more. It is preferred, and 99% or more is particularly preferred. Moreover, the fibrous activated carbon layer 2 can be made only 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, and particularly 1% by mass or less. It is preferably 0% by mass (not containing a binder component), and more preferably 0% by mass.

As a form of the fibrous activated carbon layer 2, a fibrous activated carbon aggregate in which the fibrous activated carbon is aggregated to form the fibrous activated carbon layer 2 is mentioned. The fibrous activated carbon aggregate is not particularly limited, but may be a fibrous activated carbon aggregate in which fibrous activated carbon is fixed by heat-fusible fibers or pulp, or fibrous activated carbon that is entangled with each other regardless of the binder component. A cotton-like or felt-like fibrous activated carbon aggregate integrated with, and a cotton-like or felt-like fibrous aggregate integrated by entangling the fibrous activated carbon with each other regardless of the binder component Activated carbon aggregates are preferred. Examples of fibrous activated carbon aggregates in which fibrous activated carbon is fixed by heat-fusible fibers or pulp include needle-punched nonwoven fabrics and wet papermaking nonwoven fabrics.

The mass of the fibrous activated carbon layer 2 is not particularly limited, but is preferably 120 g/m ^{2 or more, more preferably 140 g/m 2 or} more, from the viewpoint of more efficiently removing odorous substances such as methyl mercaptan under ventilation conditions. It is preferably 180 g/m ² or more, more preferably 180 g/m 2 or more. The upper limit of the mass of the fibrous activated carbon layer 2 is not particularly limited. From the viewpoint of more efficient removal of odorous substances, it is preferably 300 g/m ² or less, more preferably 240 g/m ² or less, and even more preferably 220 g/m ² .

The thickness of the fibrous activated carbon layer 2 is not particularly limited. From the viewpoint of more efficient removal of odorous substances, it is preferably 1500 to 3000 μm, more preferably 1600 to 2000 μm. The thickness of the fibrous activated carbon layer 2 is determined by observing the thickness of the deodorizing sheet 1 from the cross-sectional direction using VHX-5000 manufactured by Keyence Corporation as a microscope and measuring the thickness at arbitrarily 10 points. Let the average value of the thickness be the thickness of the fibrous activated carbon layer 2 . Moreover, the apparent density of the fibrous activated carbon layer 2 may be 0.12 g/cm ³ or less, preferably 0.07 to 0.12 g/cm ³ . Moreover, the upper limit of the apparent density can be 0.11 g/cm ³ or less. The apparent density is obtained from the mass of the fibrous activated carbon layer 2 and the thickness of the fibrous activated carbon layer 2 .

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

Examples of the fiber material (fiber material 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, cotton, and hemp. , natural fibers such as wool, regenerated fibers such as cupra rayon, viscose rayon, lyocell, etc., other than fibrous activated carbon. The content of the fibrous activated carbon in the nonwoven fabric layer 3 may be 5% by mass or less, 3% by mass or less, or 1% by mass or less, and is preferably 0% by mass (does not contain fibrous activated carbon).

The form of the nonwoven fabric layer 3 includes a long fiber nonwoven fabric or a short fiber nonwoven fabric. Examples of long-fiber nonwoven fabrics include spunbond nonwoven fabrics, tow-opened nonwoven fabrics, melt blown nonwoven fabrics made of continuous fibers, and the like. Examples of staple fiber nonwoven fabrics include needle-punched nonwoven fabrics and wet papermaking nonwoven fabrics. Among them, when the content of the fibrous activated carbon in the fibrous activated carbon layer 2 is increased to, for example, 80% by mass or more, the fibrous activated carbon layer 2 and the nonwoven fabric layer 3 are entangled to further increase the bondability, so the long fiber nonwoven fabric is used. and more preferably a nonwoven fabric made of continuous filaments. The long fiber nonwoven fabric preferably has an average fiber length of 100 mm or more, more preferably 300 mm or more. In particular, it is preferable to use a nonwoven fabric containing a tow-opened filament web from the viewpoint of further increasing the bondability of the fibrous activated carbon layer 2 and the nonwoven fabric layer 3 by entangling the fibrous activated carbon layer 2 and the nonwoven fabric layer 3 because the long fibers are easily frayed.

Moreover, it is preferable that the nonwoven fabric used as the nonwoven fabric layer 3 is not embossed. By doing so, the degree of freedom of each fiber constituting the nonwoven fabric layer 3 is increased, and the bondability of the fibrous activated carbon layer 2 and the nonwoven fabric layer 3 due to entangling, which will be described later, can be further enhanced. Examples of such a nonwoven fabric include a nonwoven fabric formed by stretching a laminated web.

The tensile strength (N/5cm) of the nonwoven fabric constituting the nonwoven fabric layer 3 is 10 to 100 N/5 cm in the MD direction (machine direction) and 10 to 100 N/5 cm in the CD direction (perpendicular to the MD direction). Also, the ratio of the tensile strength in the MD direction to the tensile strength in the CD direction (MD direction/CD direction) is 0.7 to 1.3, preferably 0.9 to 1.1. By reducing the difference between the MD direction and the CD direction in this way, it becomes easier to reduce the pressure loss when the deodorizing sheet 1 is formed by laminating the fibrous activated carbon layers 2 . In addition, in this invention, the tensile strength of a nonwoven fabric is measured and calculated as follows. That is, according to JIS L 1913: 2010 6.3, using Tensilon RTM-500 manufactured by Toyo Baldwin Co., Ltd., a test piece with a width of 50 mm and a length of 200 mm was measured under the conditions of a gripping interval of 100 mm and a tensile speed of 100 mm / min. Then, the average value of 10 samples is obtained and taken as the tensile strength.

The thickness of one layer of the 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 determined by observing the thickness of the deodorizing sheet 1 from the cross-sectional direction using VHX-5000 manufactured by KEYENCE CORPORATION as a microscope and measuring the thickness at 10 arbitrary points. The thickness of the nonwoven fabric layer 3 is defined as the average value of the ten thicknesses.

The mass per layer of the nonwoven fabric layer 3 is 5 to 50 g/m ² , more preferably 15 to 25 g/m ² . Moreover, the apparent density of the nonwoven fabric layer 3 is preferably 0.10 to 0.50 g/cm ³ , more preferably 0.30 to 0.40 g/cm ³ . The apparent density of the nonwoven fabric layer 3 is obtained from the mass of the nonwoven fabric layer 3 and the thickness of the nonwoven fabric layer 3 .

<Deodorizing sheet 1>
The deodorizing sheet 1 in the first embodiment includes 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. Laminated in order.

The form of lamination of the fibrous activated carbon layer 2 and the nonwoven fabric layer 3 may be one in which the two are integrated with an adhesive, or both may be combined with a binder component contained in one layer, specifically a heat-fusible fiber or The fibers constituting the nonwoven fabric layer 3 and the fibrous activated carbon layer 2 are integrated by fusion bonding of a thermoplastic resin, or by a needle punching method, a water punching method, or the like, regardless of adhesive or binder components. The nonwoven fabric layer 3 and the fibrous activated carbon layer 2 are integrated by entangling the constituting fibrous activated carbon at the surface portion of the nonwoven fabric layer 3 and the surface portion of the fibrous activated carbon layer 2 . Among them, the fibrous activated carbon layer 2 secures more air flow paths to reduce the pressure loss of the deodorizing sheet 1, while the content of the fibrous activated carbon in the entire deodorizing sheet 1 is increased and methyl mercaptan is used under ventilation conditions. From the viewpoint of more efficiently removing odorous substances such as It is preferable that the nonwoven fabric layer 3 and the fibrous activated carbon layer 2 are integrated by entangling them in some parts.

In the deodorant sheet 1, the ratio of the thickness of the fibrous activated carbon layer 2 to the thickness of each nonwoven fabric layer 3 (thickness of the fibrous activated carbon layer 2/thickness of each nonwoven fabric layer 3) is While reducing the pressure loss of the deodorizing sheet 1 by securing more air passages in the fibrous activated carbon layer 2, the content of the fibrous activated carbon in the entire deodorizing sheet 1 is increased, and methyl mercaptan or the like is released under ventilation conditions. From the viewpoint of more efficient removal of odorous substances, it is preferably 20 to 50, more preferably 25 to 40, and even more preferably 30 to 40.

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

The deodorizing sheet 1 preferably has a pressure loss of 40 Pa or less by the following method. As a result, it can be used more preferably in filters of air cleaners and the like. Further, from the viewpoint of reducing the pressure loss of the deodorizing sheet 1 and more efficiently removing malodorous substances such as methyl mercaptan under ventilation conditions, the pressure loss is preferably 20 to 40 Pa.
<Pressure loss test method>
JIS B 9927: 1999 3.2 "Pressure loss test" of "Appendix (regulation) clean room air filter media performance test method", a deodorant sheet cut into a circle with a diameter of 110 mm was used as a measurement sample, The difference in static pressure between the upstream side and the downstream side of the activated carbon sheet when air is sucked at a linear velocity of 5 m/s is measured with a differential pressure gauge, and the measured value is taken to be an effective numerical value up to the one digit.

Moreover, since the deodorizing sheet 1 of the present invention contains fibrous activated carbon, it is possible to efficiently remove malodorous substances such as methyl mercaptan under ventilation conditions. As an example of preferable deodorizing performance provided by the deodorizing sheet 1 of the first embodiment, the removal rate of methyl mercaptan measured by the following measuring method is preferably 75% or more, more preferably 90% or more, and 95% or more. % or more is more preferable.
<Measurement method>
FIG. 3 is a schematic diagram illustrating a method for measuring the pressure loss of the deodorizing sheet in the present invention. First, the Tedlar bag 4 is filled with 1.5 L of gas at a temperature of 20° C. and a humidity of 80% RH, which is obtained by mixing air components and methyl mercaptan gas so that the concentration of methyl mercaptan is 20 ppm. Next, the Tedlar bag and the separately vacuumed Tedlar bag 5 are connected by inserting a glass column 7 packed with the deodorizing sheet 1 cut into a circle with a diameter of 15 mm. Next, the evacuated Tedlar bag 5 is placed in a sealable case 8 and sealed. Then, the air in the case 8 is sucked at a constant air volume using the pump 9 so that the ventilation surface of the deodorizing sheet 1 is evenly ventilated at a linear velocity of 0.5 m / s, and the gas in the Tedlar bag 4 is vacuumed. Pour completely into the drawn Tedlar bag 5. The concentration of methyl mercaptan in the Tedlar bag 5 to which it is poured is measured with a gas detector tube, and the gas removal rate is calculated from the change in concentration before and after ventilation (gas removal rate = (20 ppm - methyl in the Tedlar bag 5 after ventilation Mercaptan concentration (ppm)/20 ppm×100 (%)).

The method for manufacturing the deodorizing sheet 1 of the first embodiment is not particularly limited. For example, the following manufacturing methods are mentioned. That is, as the manufacturing method, a preparation step of preparing a fibrous activated carbon aggregate to be the fibrous activated carbon layer 2 and a nonwoven fabric to be the nonwoven fabric layer 3 containing fibers other than the fibrous activated carbon, and constructing the prepared nonwoven fabric A manufacturing method including a lamination step of laminating the nonwoven fabric layer 3 and the fibrous activated carbon layer 2 by entangling and integrating the fibers and the fibrous activated carbon constituting the prepared fibrous activated carbon aggregate.

In the preparation step, the nonwoven fabric (raw material nonwoven fabric before integration) used as the nonwoven fabric layer 3 preferably has an apparent density of 0.25 g/cm ³ or less, preferably 0.10 to 0.25 g/cm. ³ is more preferable. By using a nonwoven fabric having such a density as the raw material nonwoven fabric, it is possible to further enhance the bondability of the fibrous activated carbon layer 2 and the nonwoven fabric layer 3 by entangling them. The thickness of the raw nonwoven fabric is measured according to JIS L 1913:2010 6.1.1 Method A, and the apparent density is obtained from the thickness and mass.

In the preparation step, the fibrous activated carbon aggregate to be the fibrous activated carbon layer 2 is a fibrous activated carbon aggregate in which the fibrous activated carbon is fixed by heat-fusible fibers or pulp, or a fibrous activated carbon aggregate regardless of the binder component. A cotton-like or felt-like fibrous activated carbon aggregate in which activated carbons are entangled with each other and integrated. Among them, felt-like fibrous activated carbon aggregates formed by entangling fibrous activated carbons irrespective of the binder component are integrated, for example, by opening and mixing fibrous activated carbons by an airlaid method or a carding method. A fibrous activated carbon aggregate made into a felt by performing the

In the lamination step, the prepared nonwoven fabric, the fibrous activated carbon aggregate, and the prepared nonwoven fabric are stacked in this order, and the fibers constituting the nonwoven fabric and the fibrous activated carbon constituting the fibrous activated carbon aggregate are entangled, and the nonwoven fabric and By integrating the fibrous activated carbon aggregate, the nonwoven fabric layer 3, the fibrous activated carbon layer 2, and the nonwoven fabric layer 3 are laminated and formed. Examples of the entangling method include a needle punch method and a water punch method, and the needle punch method is preferred.

Thus, the deodorizing sheet 1 of the first embodiment can be obtained.

(Second embodiment)
FIG. 2 is a cross-sectional schematic diagram showing the deodorizing sheet 11 of the second embodiment. As shown in FIG. 2, the deodorizing sheet 11 of the present invention consists of a fibrous activated carbon layer 12 containing fibrous activated carbon.

<Fibrous Activated Carbon>
The preferred configuration of the fibrous activated carbon in the deodorizing sheet 11 of the second embodiment is the same as described above in the description of the deodorizing sheet 1 of the first embodiment.
<Fibrous activated carbon layer 12>
A deodorizing sheet 11 of the second embodiment includes a fibrous activated carbon layer 12 .

The fibrous activated carbon layer 12 contains the fibrous activated carbon described above. This makes it possible to efficiently remove odorous substances such as methyl mercaptan under ventilation conditions.

The fibrous activated carbon layer 12 can contain components other than the fibrous activated carbon. Examples of other components include granular or powdery activated carbon, pulp, heat-fusible fibers, and thermoplastic resins (excluding thermoplastic resins contained in heat-fusible fibers) as binder components. .

When the fibrous activated carbon layer 12 contains granular or powdered activated carbon, its content is, for example, 10 to 75% by mass, preferably 20 to 65% by mass. On the other hand, granular or powdery activated carbon can be substantially not contained in the fibrous activated carbon layer 12, and specific content ratios are 5% by mass or less, 3% by mass or less, and 1% by mass or less. and preferably 0% by mass (not containing granular or powdered activated carbon).

The above-mentioned pulp does not fix the filter material by heat-sealing itself, but is fibrillated to entangle the filter material and shape it. Examples of the pulp include cellulose pulp and acrylic pulp. The freeness of the pulp is preferably 10 to 200 mL as measured according to JIS P 8121-2:2012. A preferred pulp melting point is, for example, a melting point of 150° C. or higher, preferably 200° C. or higher. In addition, in this invention, when it does not have a melting point, let a softening point be a melting point. In the present invention, the melting point is measured using a differential scanning calorimeter DSC-7 manufactured by PerkinElmer at a heating rate of 20° C./min. When pulp is contained in the fibrous activated carbon layer 12, its content is, for example, 1 to 25% by mass, preferably 3 to 20% by mass. On the other hand, from the viewpoint of facilitating the apparent density of the fibrous activated carbon layer 12 to be described later, the fibrous activated carbon layer 2 can be substantially free of pulp. .5% by mass or less, preferably 0% by mass (not containing pulp).

The above heat-fusible fibers are also called binder fibers, and usually can be melted by heating to fix a filter medium or the like. The heat-fusible component contained in the heat-fusible fiber 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 obtained by copolymerizing a copolymer component such as isophthalic acid. In addition, the heat-fusible fiber that can be included in the activated carbon molded body is a full-fusion type composed of only a single heat-fusible component, or a heat-fusible component in the sheath, a melting point in the core, and a sheath with a melting point of and preferably 20° C. or higher, more preferably 30° C. or higher than the melting point of the core-sheath type heat-fusible fiber. 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 point is measured using a differential scanning calorimeter DSC-7 manufactured by PerkinElmer at a heating rate of 20° C./min. When the fibrous activated carbon layer 12 contains heat-fusible fibers, the content is, for example, 10 to 70% by mass, preferably 15 to 45% by mass.

The thermoplastic resin (excluding the thermoplastic resin contained in the heat-fusible fiber) as the binder component includes olefin resins (polyethylene, polypropylene, ethylene-vinyl acetate copolymer, ethylene-(meth)acrylic acid copolymers, ethylene-(meth)acrylic acid ester copolymers, etc.), vinyl acetate resins (polyvinyl acetate, vinyl acetate-vinyl chloride copolymers, etc.), polyvinyl alcohol resins (polyvinyl alcohol, ethylene-vinyl alcohol copolymers, etc.), acrylic resins, styrene resins (polystyrene, AS resin, ABS resin, etc.), polyester resins, polyamide resins, thermoplastic polyurethane resins, cellulose derivatives (methylcellulose, ethylcellulose, carboxymethylcellulose, hydroxyethylcellulose, etc.) cellulose ethers, cellulose esters such as cellulose acetate), natural resins (shellac, rosin, etc.), polysaccharides (sodium alginate, tragacanth gum, gum arabic, pectin, chitosan, gelatin). When the fibrous activated carbon layer 12 contains the thermoplastic resin, the content is, for example, 10 to 50% by mass, preferably 10 to 30% by mass. On the other hand, particularly in the first embodiment, the content of fibrous activated carbon in the entire deodorizing sheet 11 is increased while securing more air flow paths in the fibrous activated carbon layer 12 and reducing the pressure loss of the deodorizing sheet 1. From the viewpoint of more efficiently removing odorous substances such as methyl mercaptan under conditions of higher aeration, the fibrous activated carbon layer 12 can be substantially free of the thermoplastic resin. The content ratio includes 5% by mass or less, 3% by mass or less, and 1% by mass or less, and does not contain 0% by mass (thermoplastic resin (excluding the thermoplastic resin contained in the heat-fusible fiber). ) is preferred.

As for the content of fibrous activated carbon in the fibrous activated carbon layer 12, it is possible to secure more air flow paths in the fibrous activated carbon layer 12 and reduce the pressure loss of the deodorizing sheet 11. 30% by mass or more is preferable, 30 to 90% by mass is more preferable, and 55 to 85% by mass is more preferable from the viewpoint of more efficiently removing odorous substances such as methyl mercaptan under ventilation conditions by increasing the content of activated carbon. is more preferred.

The fibrous activated carbon layer 12 may be in the form of a fibrous activated carbon aggregate in which fibrous activated carbon is fixed by heat-fusible fibers or pulp, or a flocculated fibrous activated carbon aggregate that is not based on heat-fusible fibers or pulp. and a fibrous activated carbon aggregate obtained by making fibrous activated carbon into felt. Examples of fibrous activated carbon aggregates in which fibrous activated carbon is fixed by heat-fusible fibers or pulp include needle-punched nonwoven fabrics and wet papermaking nonwoven fabrics.

Among them, the fibrous activated carbon layer 12 contains fibrous activated carbon and heat-fusible fibers, and the fibrous activated carbon and the heat-fusible fibers are integrated by entangling in a state in which the heat-fusible fibers are not melted. A fibrous activated carbon aggregate is preferred. That is, by including the heat-fusible fibers in the fibrous activated carbon layer 12 without melting, more air flow paths are secured in the fibrous activated carbon layer 12, and the pressure loss of the deodorizing sheet 11 can be further reduced. You can do more. In order to do this, in the production of the deodorizing sheet 11, if the temperature is (the melting point Tm of the heat-fusible component of the heat-fusible fiber - (minus) 20°C) or higher (for example, if the melting point is 110°C, 110-20 = 90°C or higher), the fibrous activated carbon and the heat-fusible fibers are entangled and integrated by a needle punch method, a water punch method, or the like. , More preferably, the fibrous activated carbon and the heat-fusible fibers are entangled and integrated by a needle punch method, a water punch method, or the like, and the heat treatment is performed at a temperature higher than the glass transition point of the heat-fusible component, (the heat-fusible It is possible by heat-treating under a temperature condition of less than the melting point Tm-20° C. of the adhesive component (for example, when the melting point is 110° C., 110−20=less than 90° C.).

The mass of the fibrous activated carbon layer 12 is preferably 20 g/m ² or more, more preferably 50 g/m ² or more, from the viewpoint of more efficiently removing odorous substances such as methyl mercaptan under ventilation conditions. Although the upper limit is not particularly limited, the content of fibrous activated carbon in the entire deodorizing sheet 11 is increased while reducing the pressure loss of the deodorizing sheet 11, thereby more efficiently removing odorants such as methyl mercaptan under ventilation conditions. 100 g/m ² or less is preferable from the viewpoint of performance.

As for the thickness of the fibrous activated carbon layer 12, the pressure loss of the deodorizing sheet 11 is reduced, and the content of the fibrous activated carbon in the entire deodorizing sheet 11 is increased to remove odorous substances such as methyl mercaptan under ventilation conditions. From the viewpoint of more efficient operation, the thickness is preferably 200 μm to 1000 μm, more preferably 500 μm to 1000 μm. The thickness of the fibrous activated carbon layer 12 is determined by observing the thickness of the deodorant sheet 1 from the cross-sectional direction using VHX-5000 manufactured by Keyence Corporation as a microscope and measuring the thickness at 10 points. Let the average value of the thickness be 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 or less, preferably 0.11 g/cm ³ or less, more preferably 0.10 g/cm ³ or less. Although the lower limit is not particularly limited, it may be, for example, 0.05 g/cm ³ or more, and 0.08 g/cm ³ or more. The apparent density is obtained from the mass of the fibrous activated carbon layer 12 and the thickness of the fibrous activated carbon layer 12 .

The deodorizing sheet 11 preferably has a pressure loss of 30 Pa or less, more preferably 25 Pa or less, even more preferably 10 Pa or less, by the following method. As a result, it can be suitably used for filters of air cleaners and the like. From the viewpoint of reducing the pressure loss of the deodorizing sheet 1 and more efficiently removing malodorous substances such as methyl mercaptan under ventilation conditions, the pressure loss is preferably 5 to 10 Pa.
<Pressure loss test method>
JIS B 9927: 1999 According to 3.2 "Pressure loss test" of "Annex (regulation) clean room air filter media performance test method", the activated carbon sheet was cut into a circle with a diameter of 110 mm as a measurement sample. Measure the difference in static pressure between the upstream side and the downstream side of the activated carbon sheet with a differential pressure gauge when air is sucked at a linear velocity of 5 m/s, and the measured value is an effective value up to the first place. .

Further, since the deodorizing sheet 11 of the present invention contains fibrous activated carbon, it is possible to efficiently remove malodorous substances such as methyl mercaptan under ventilation conditions. As an example of preferable deodorizing performance provided by the deodorizing sheet 11 of the first embodiment, the removal rate of methyl mercaptan measured by the following measuring method is preferably 50% or more, more preferably 60% or more.
<Measurement method>
FIG. 3 is a schematic diagram illustrating a method for measuring the pressure loss of the deodorizing sheet in the present invention. First, the Tedlar bag 4 is filled with 1.5 L of gas at a temperature of 20° C. and a humidity of 80% RH, which is obtained by mixing air components and methyl mercaptan gas so that the concentration of methyl mercaptan is 20 ppm. Next, the Tedlar bag and the separately vacuumed Tedlar bag 5 are connected by inserting a glass column 7 packed with a deodorizing sheet 11 cut into a circle with a diameter of 15 mm. Next, the evacuated Tedlar bag 5 is placed in a sealable case 8 and sealed. Then, the air in the case 8 is sucked at a constant air volume using the pump 9 so that the ventilation surface of the deodorizing sheet 11 is evenly ventilated at a linear velocity of 0.5 m / s, and the gas in the Tedlar bag 4 is vacuumed. Pour completely into the drawn Tedlar bag 5. The concentration of methyl mercaptan in the Tedlar bag 5 to which it is poured is measured with a gas detector tube, and the gas removal rate is calculated from the change in concentration before and after ventilation (gas removal rate = (20 ppm - methyl in the Tedlar bag 5 after ventilation Mercaptan concentration (ppm)/20 ppm×100 (%)).

The method for manufacturing the deodorizing sheet 11 of the second embodiment is not particularly limited. For example, the following manufacturing methods are mentioned. That is, including a step of preparing fibrous activated carbon and heat-fusible fibers, a step of entangling and integrating the fibrous activated carbon and the heat-fusible fibers, (heat fusion of heat-fusible fibers (eg, if the melting point is 110° C., then 110−20=90° C. or higher) without heat treatment. As a result, the pressure loss of the deodorizing sheet 11 can be further reduced. In addition, the sheet in which the fibrous activated carbon and the heat-fusible fibers are integrated by the entanglement is heated to a temperature higher than the glass transition point of the heat-fusible component of the heat-fusible fiber (the melting point of the heat-fusible component). Tm−20° C.) (for example, if the melting point is 110° C., 110−20=less than 90° C.). By performing such a heat treatment, the fibrous activated carbon and the heat-fusible fibers are heat-set in a state in which the heat-fusible fibers are not melted, and the deodorant sheet 11 is thus entangled and integrated, thereby improving the strength of the deodorizing sheet 11. and reduction of pressure loss can be further compatible.

<Use of the deodorant sheet of the present invention>
Applications of the deodorizing sheet of the present invention are not particularly limited. For example, it can be used for filters of air purifiers and sanitary products used at medical sites and at home. Further, the deodorizing sheet of the present invention can be subjected to known processing such as pleating. The deodorant sheet of the present invention can also be used in combination with other functional sheets such as other deodorant sheets and absorbent sheets.

EXAMPLES The present invention will be described in detail below with reference to examples and comparative examples. However, the invention is not limited to the examples.

1. Materials Used in Examples (1) Fibrous activated carbon contained in fibrous activated carbon layer 2 or 12 Fibrous activated carbon A (trade name A-10 manufactured by Ador Co., Ltd., coal pitch type, fiber diameter 17 μm, specific surface area 1300 m ² /g, tensile strength 250 N/mm ² )
・Fibrous activated carbon B (trade name A-7 manufactured by AD'ALL Co., Ltd., coal pitch type, fiber diameter 17 μm, specific surface area 850 m ² /g, tensile strength 330 N/mm ² )
・Fibrous activated carbon C (trade name A-15 manufactured by Ador Co., Ltd., coal pitch type, fiber diameter 16 μm, specific surface area 1700 m ² /g, tensile strength 220 N/mm ² )

(2) Non-woven fabric contained in non-woven fabric layer 3 Product name Unicel (registered trademark) BT-0403W2 manufactured by Unicel Co., Ltd. (mass 20 g/m ² , thickness 0.09 mm, apparent density 0.22 g/cm ³ , MD direction tensile Tensile strength 50 N/5 cm, TD direction tensile strength 50 N/5 cm, containing polyethylene terephthalate filaments and polypropylene fibers, including tow-opened polyethylene terephthalate filament webs, non-embossed filament nonwoven fabric)

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

2. Examples <Example 1>
The fibrous activated carbon A and two nonwoven fabrics included in the nonwoven fabric layer 3 were prepared.

The mass of the fibrous activated carbon A for the fibrous activated carbon layer 2 was set to 190 g/m ² , and the fibrous activated carbon A was opened and mixed using a carding machine to prepare a felt-like fibrous activated carbon aggregate. Next, a nonwoven fabric, a felt-like fibrous activated carbon aggregate, and a nonwoven fabric are laminated in this order, and one of the nonwoven fabrics is needle-punched so that the deodorizing sheet 1 has a thickness of 2000 μm. were integrated to obtain the deodorizing sheet 1 of Example 1, which is the first embodiment, illustrated in FIG. In the obtained deodorizing sheet 1, the fibrous activated carbon layer 2 had a thickness of 1892 μm, the nonwoven fabric layer 3 had a thickness of 54 μm, and the deodorizing sheet 1 had a thickness of 2000 μm. In addition, the fibers forming the nonwoven fabric layer 3 and the fibrous activated carbon forming the fibrous activated carbon layer 2 were entangled at the surface portion of the nonwoven fabric layer 3 and the surface portion of the fibrous activated carbon layer 2 .

<Example 2>
The fibrous activated carbon A and two nonwoven fabrics included in the nonwoven fabric layer 3 were prepared.

A felt-like fibrous activated carbon aggregate was prepared by setting the mass of the fibrous activated carbon A for the fibrous activated carbon layer 2 to 160 g/m ² and opening and mixing the fibrous activated carbon A using a carding machine. Next, a nonwoven fabric, a felt-like fibrous activated carbon aggregate, and a nonwoven fabric are laminated in this order, and one of the nonwoven fabrics is needle-punched so that the deodorizing sheet 1 has a thickness of 1900 μm. were integrated to obtain the deodorizing sheet 1 of Example 2, which is the first embodiment, illustrated in FIG. In the obtained deodorizing sheet 1, the fibrous activated carbon layer 2 had a thickness of 1786 μm, the nonwoven fabric layer 3 had a thickness of 57 μm, and the deodorizing sheet 1 had a thickness of 1900 μm. In addition, the fibers forming the nonwoven fabric layer 3 and the fibrous activated carbon forming the fibrous activated carbon layer 2 were entangled at the surface portion of the nonwoven fabric layer 3 and the surface portion of the fibrous activated carbon layer 2 .

<Example 3>
The fibrous activated carbon B and two nonwoven fabrics included in the nonwoven fabric layer 3 were prepared.

The mass of the fibrous activated carbon B for the fibrous activated carbon layer 2 was set to 190 g/m ² , and the fibrous activated carbon B was opened and mixed using a carding machine to prepare a felt-like fibrous activated carbon aggregate. Next, a nonwoven fabric, a felt-like fibrous activated carbon aggregate, and a nonwoven fabric are laminated in this order, and one of the nonwoven fabrics is needle-punched so that the deodorizing sheet 1 has a thickness of 2000 μm. were integrated to obtain the deodorizing sheet 1 of Example 3, which is the first embodiment, illustrated in FIG. In the obtained deodorizing sheet 1, the fibrous activated carbon layer 2 had a thickness of 1894 μm, the nonwoven fabric layer 3 had a thickness of 53 μm, and the deodorizing sheet 1 had a thickness of 2000 μm. In addition, the fibers forming the nonwoven fabric layer 3 and the fibrous activated carbon forming the fibrous activated carbon layer 2 were entangled at the surface portion of the nonwoven fabric layer 3 and the surface portion of the fibrous activated carbon layer 2 .

<Example 4>
The fibrous activated carbon B and the heat-fusible fibers contained in the fibrous activated carbon layer 12 were prepared.

The prepared fibrous activated carbon B and the heat-fusible fibers were added so that the mass ratio of the fibrous activated carbon B to the heat-fusible fibers (mass of fibrous activated carbon B/mass of heat-fusible fibers) was 37/63. Then, the fibers were opened and mixed by a carding machine to produce a fibrous activated carbon aggregate having a small thickness. A plurality of the fibrous activated carbon aggregates are laminated, then needle-punched to entangle the fibrous activated carbon B and the heat-fusible fibers. The fusible component was melted to obtain the deodorizing sheet 11 of Example 4, which is the second embodiment, illustrated in FIG. The thickness of the obtained deodorant sheet 11 was 220 μm. Also, in the deodorizing sheet 11, the heat-fusible fibers were present in a molten state.

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

The prepared fibrous activated carbon B and the heat-fusible fibers were added so that the mass ratio of the fibrous activated carbon B to the heat-fusible fibers (mass of fibrous activated carbon B/mass of heat-fusible fibers) was 37/63. Then, the fibers were opened and mixed by a carding machine to produce a fibrous activated carbon aggregate having a small thickness. A plurality of the fibrous activated carbon aggregates are laminated, then needle-punched to entangle the fibrous activated carbon B and the heat-fusible fibers, and then heat-set in an oven at a temperature of 70°C. 2, a deodorizing sheet 11 of Example 5, which is the second embodiment, was obtained. The thickness of the obtained deodorant sheet 11 was 350 µm. Also, in the deodorizing sheet 11, the heat-fusible fibers existed in an unmelted state.

<Example 6>
The fibrous activated carbon A and the heat-fusible fibers contained in the fibrous activated carbon layer 12 were prepared.

The prepared fibrous activated carbon A and the heat-fusible fibers were mixed 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. Then, the fibers were opened and mixed by a carding machine to produce a fibrous activated carbon aggregate having a small thickness. A plurality of the fibrous activated carbon aggregates are laminated, then needle-punched to entangle the fibrous activated carbon A and the heat-fusible fibers. The fusible component was melted to obtain the deodorant sheet 11 of Example 6, which is the second embodiment, illustrated in FIG. The thickness of the obtained deodorant sheet 11 was 550 µm. Also, in the deodorizing sheet 11, the heat-fusible fibers were present in a molten state.

<Example 7>
The fibrous activated carbon A and the heat-fusible fibers contained in the fibrous activated carbon layer 12 were prepared.

The prepared fibrous activated carbon A and the heat-fusible fibers were mixed 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. Then, the fibers were opened and mixed by a carding machine to produce a fibrous activated carbon aggregate having a small thickness. A plurality of the fibrous activated carbon aggregates are laminated, then needle-punched to entangle the fibrous activated carbon A and the heat-fusible fibers, and then heat-set in an oven at a temperature of 70° C. to heat set. 2, a deodorizing sheet 11 of Example 7, which is the second embodiment, was obtained. The thickness of the obtained deodorant sheet 11 was 700 µm. Also, in the deodorizing sheet 11, the heat-fusible fibers existed in an unmelted state.

<Example 8>
The fibrous activated carbon C and the heat-fusible fibers contained in the fibrous activated carbon layer 12 were prepared.

The prepared fibrous activated carbon C and the heat-fusible fibers were mixed so that the mass ratio of the fibrous activated carbon C and the heat-fusible fibers (mass of the fibrous activated carbon C/mass of the heat-fusible fibers) was 75/25. Then, the fibers were opened and mixed by a carding machine to produce a fibrous activated carbon aggregate having a small thickness. A plurality of the fibrous activated carbon aggregates are laminated, then needle-punched to entangle the fibrous activated carbon C and the heat-fusible fibers. The fusible component was melted to obtain the deodorizing sheet 11 of Example 8, which is the second embodiment, illustrated in FIG. The thickness of the obtained deodorant sheet 11 was 520 μm. Also, in the deodorizing sheet 11, the heat-fusible fibers were present in a molten state.

3. Evaluation method (1) Specific surface area, fiber diameter and tensile strength of fibrous activated carbon Evaluation was performed by the methods described above.

(2) Melting point and glass transition point of heat-fusible component of heat-fusible fiber Evaluation was performed by the method described above.

(3) Thickness of fibrous activated carbon layer, non-woven fabric layer and deodorizing sheet in deodorizing sheet Evaluation was performed by the method described above.

(4) Pressure loss of deodorizing sheet Cut the activated carbon sheet into a circle with a diameter of 110 mm according to 3.2 "Pressure loss test" of JIS B 9927: 1999 "Annex (regulation) Clean room air filter media performance test method". Using the obtained product as a measurement sample, the difference in static pressure between the upstream side and the downstream side of the activated carbon sheet when air is sucked at a linear velocity of 0.5 m / s is measured with a differential pressure gauge. Valid values were taken up to the first place.

(5) Removal rate of methyl mercaptan <measurement method>
FIG. 3 is a schematic diagram illustrating a method for measuring the pressure loss of the deodorizing sheet in the present invention. First, the Tedlar bag 4 was filled with 1.5 L of gas at a temperature of 20.degree. Next, the Tedlar bag and the separately vacuumed Tedlar bag 5 were connected by inserting a glass column 7 packed with a deodorizing sheet cut into a circle with a diameter of 15 mm. Next, the evacuated Tedlar bag 5 was placed in a sealable case 8 and sealed. Then, the air in the case 8 is sucked at a constant air volume using the pump 9 so that the ventilation surface of the deodorizing sheet is evenly ventilated at a linear velocity of 0.5 m / s, and the gas in the Tedlar bag 4 is vacuumed. It was completely drained into a Tedlar bag 5. The concentration of methyl mercaptan in the Tedlar bag 5 to which it was poured was measured with a gas detector tube, and the gas removal rate was calculated from the change in concentration before and after ventilation (gas removal rate = (20 ppm - methyl in the Tedlar bag 5 after ventilation Mercaptan concentration (ppm)/20 ppm×100 (%)).
Those with a removal rate of 20% or more were accepted as those capable of efficiently removing odorous substances such as methyl mercaptan under ventilation conditions.

Table 1 shows the evaluation results and the like of each example.

As is clear from Table 1, the deodorizing sheets of Examples 1 to 8 were capable of efficiently removing odorants such as methyl mercaptan under ventilation conditions.

In particular, in the sheets of Examples 1 to 3, 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 are laminated in this order. Therefore, while reducing the pressure loss of the deodorizing sheet, the content of fibrous activated carbon in the entire deodorizing sheet is increased to more efficiently remove odorants such as methyl mercaptan under ventilation conditions. It was possible.

Among them, in the deodorizing sheets of Examples 1 and 2, the specific surface area of the fibrous activated carbon was 1200 to 1400 m ² /g, and the tensile strength was 240 to 280 N/m ² . While efficiently removing the odorous substances, it is easier to suppress the increase in pressure loss due to the deformation of the fibrous activated carbon under ventilation conditions.

Further, when comparing Examples 4 and 5, and Examples 6 and 7, in Examples 5 and 7, the fibrous activated carbon layer contains fibrous activated carbon and heat-fusible fibers, and the heat-fusible fibers Since the fibrous activated carbon and the heat-fusible fibers were integrated by entangling without being melted, compared to Examples 6 and 8, the air flow path was formed in the fibrous activated carbon layer 12. A larger amount can be secured, the pressure loss of the deodorizing sheet 11 can be further reduced, and malodorous substances such as methyl mercaptan can be removed more efficiently under ventilation conditions.

1, 11: Deodorizing sheet 2, 12: Fibrous activated carbon layer 3: Nonwoven fabric layer 4, 5: Tedlar bag 6: Glass column 7: Case 8: Pump

Claims (8)

A deodorizing sheet comprising a fibrous activated carbon layer containing fibrous activated carbon. 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 a nonwoven fabric layer containing fibers other than fibrous activated carbon are laminated in this order. The deodorizing sheet according to claim 2, wherein the fibrous activated carbon content in the fibrous activated carbon layer is 90% by mass or more. The deodorizing sheet according to claim 2 or 3, wherein the ratio of the mass of activated carbon contained in said deodorizing sheet to the mass of said deodorizing sheet is 70 to 95% by mass. The fibers constituting the nonwoven fabric layer and the fibrous activated carbon constituting the fibrous activated carbon layer are entangled at the surface portion of the nonwoven fabric layer and the surface portion of the fibrous activated carbon layer, whereby the nonwoven layer and the fibrous activated carbon are entangled. The deodorizing sheet according to any one of claims 2 to 4, wherein the deodorizing sheet is integrated with the layer. The deodorizing sheet according to any one of claims 2 to 5, wherein the nonwoven fabric layer contains long fiber nonwoven fabric and is not embossed. 2. The ratio of the thickness of said fibrous activated carbon layer to the thickness of said nonwoven fabric layer (thickness of fibrous activated carbon layer/thickness of nonwoven fabric layer) is 20 to 50. 7. The deodorizing sheet according to any one of 6. The sheet according to any one of claims 1 to 7, wherein the fibrous activated carbon layer has an apparent density of 0.11 or less.

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