JP7658147B2 - Sound-absorbing sheet and stoma appliance - Google Patents

Description

This disclosure relates to sound-absorbing sheets and stoma appliances.

Conventionally, sheets made of fibrous materials such as glass wool or foamed materials such as urethane foam have been widely used as sound-absorbing sheets. Conventionally, such sound-absorbing sheets have been used by being fixed to an adherend with an adhesive or pressure-sensitive adhesive.
However, depending on the application of the sound-absorbing sheet, there are cases where it is desired that the sound-absorbing sheet have both adhesiveness and releasability. That is, there are cases where a sound-absorbing sheet is required to have both the ability to adhere to an adherend with sufficient adhesive strength while it is required to be attached to the adherend (adhesiveness), and the ability to be peeled cleanly from the adherend without leaving any adhesive on the adherend when peeled off from the adherend (releasability).

For example, appliances (stoma appliances) that contain waste material discharged from an artificial anus (stoma) are required to have a sound-absorbing mechanism to reduce the sound emitted from the stoma. When a person wearing a stoma appliance generates gas in the intestines, this gas may be discharged from the stoma and produce a sound (discharge sound). The generation of such discharge sound is extremely disruptive to the wearer in social situations such as meetings, customer service, and concerts, and there is a strong demand for reducing the discharge sound. Therefore, there is a demand for stoma appliances with sound-absorbing mechanisms.

As an example of a stoma appliance with a sound-absorbing mechanism, a stoma appliance has been proposed in which a sound-absorbing nonwoven material or a sound-absorbing multilayer film is bonded to the outer surface of the pouch of the stoma appliance to form an integrated structure (Patent Document 1). The sound-absorbing nonwoven material contains fibers containing a triblock copolymer containing a polystyrene block and a vinyl-bond-rich rubber midblock. The sound-absorbing multilayer film contains at least one layer containing a triblock copolymer containing a polystyrene block and a vinyl-bond-rich rubber midblock.

As another example, a sound reduction device has been proposed in which a proximal thin film and a distal thin film are attached to the pouch of a stoma appliance (Patent Document 2). The thin film is made of a material selected from the group consisting of silicone, polyethylene, polyethylene terephthalate, polypropylene, and PVC.

Special table 2015-503405 publication Patent No. 6557265

It is preferable that the sound absorbing mechanism for reducing noise emitted from the stoma is easily detachable from the stoma appliance. If the sound absorbing mechanism is easily detachable, the wearer of the stoma appliance can remove the sound absorbing mechanism from the stoma appliance when, for example, taking a bath, and then attach the sound absorbing mechanism to the stoma appliance again after bathing. This attachment and detachment prevents hot and cold water from entering the sound absorbing mechanism when bathing. Furthermore, if the sound absorbing mechanism is a sheet made of a fiber material or a foam material, it can be made lighter, so that even if the stoma appliance has a sound absorbing mechanism, it does not place any particular burden on the wearer of the stoma appliance.

However, in a stoma appliance configured as in Patent Document 1, the sound-absorbing material cannot be removed from the stoma appliance, so if the stoma appliance gets wet during bathing or the like, it becomes difficult to remove moisture from the sound-absorbing material, making the wearer uncomfortable. Furthermore, when the sound-absorbing material absorbs moisture, its sound-absorbing performance decreases.

In addition, even in a stoma appliance configured as in Patent Document 2, the proximal and distal thin films serving as sound reduction devices cannot be removed from the stoma appliance. In addition, the proximal and distal thin films that are attached as sound reduction devices have elasticity but insufficient sound absorption performance.

On the other hand, when using a conventional sound-absorbing sheet as a sound-absorbing mechanism in a stoma appliance, there are methods such as attaching the sound-absorbing sheet to the stoma appliance with a fixing belt, or pressing the sound-absorbing sheet against the stoma appliance from above (the outside of the body) with a belly band-like cloth, but these methods have problems such as being bulky when in use and the need to prepare separate accessories specifically for these. Also, sound-absorbing sheets made of a single material such as urethane foam do not have sufficient sound absorption properties.

The present disclosure has been made in consideration of these points, and has as its main objective to provide a sound-absorbing sheet that has excellent sound absorption properties, i.e., good adhesion to the adherend and good releasability, and a stoma appliance that has this sound-absorbing sheet.

The sound-absorbing sheet of the present disclosure has a laminated structure in which an adhesive layer and a foamed adsorption sound-absorbing layer are laminated in this order on a substrate, the foamed adsorption sound-absorbing layer being composed of a foamed (meth)acrylic ester polymer, and the thickness of the foamed adsorption sound-absorbing layer is 150 μm or more and 5000 μm or less.

In the sound-absorbing sheet of the present disclosure, the foamed sound-absorbing layer may have a basis weight of 60 g/m ² or more and 600 g/m ² or less.

In the sound-absorbing sheet of the present disclosure, the foaming ratio of the foamed, adsorbent, sound-absorbing layer may be 2.0 or more and 4.0 or less.

In the sound-absorbing sheet of the present disclosure, the adhesive layer may be made of a (meth)acrylic acid ester copolymer.

In the sound-absorbing sheet of the present disclosure, the substrate may include polyurethane foam.

In the sound-absorbing sheet of the present disclosure, the substrate has a laminated structure in which a first substrate layer and a second substrate layer are laminated, the first substrate layer has an opening and a notch in a part of the outer periphery of the first substrate layer, the notch is connected to the opening, and the foamed adsorption sound-absorbing layer may be provided on the side of the first substrate layer opposite to the side on which the second substrate layer is located.

In the sound absorbing sheet of the present disclosure, the thickness of the first base material layer may be greater than the thickness of the second base material layer.

The stoma appliance of the present disclosure comprises a base plate that is attached to the skin around the stoma and has a stoma hole through which the stoma is inserted, a pouch that is connected to the base plate and contains waste from the stoma, and the sound-absorbing sheet that is attached to the surface of the pouch, and the sound-absorbing sheet is detachably attached to the surface of the pouch on the side of the foamed, adsorbent sound-absorbing layer.

In the stoma appliance of the present disclosure, the sound-absorbing sheet may be attached in a position that covers the stoma hole when viewed from a direction perpendicular to the base plate.

According to the present disclosure, it is possible to provide a sound-absorbing sheet that has excellent sound absorbing properties, and that combines good adhesion to an adherend and good releasability.
Furthermore, in the stoma appliance of the present disclosure, the sound-absorbing sheet of the present disclosure can be easily attached and detached, and when the sound-absorbing sheet of the present disclosure is worn, the noise emitted from the stoma can be effectively reduced.

FIG. 1 is a cross-sectional view showing an example of a sound-absorbing sheet according to the present disclosure. FIG. 3 is a cross-sectional view showing another example of the sound-absorbing sheet of the present disclosure. A process diagram showing an example of a method for producing a sound-absorbing sheet according to the present disclosure. A process diagram showing another example of the method for producing a sound-absorbing sheet according to the present disclosure. FIG. 5 is a diagram for explaining the first laminate shown in FIG. 4 . FIG. 1 shows an example of a stoma appliance according to the present disclosure. FIG. 7 is a cross-sectional view showing an example of the configuration of the stoma appliance shown in FIG. FIG. 1 is a diagram showing an example of a sound-absorbing sheet according to a stoma appliance of the present disclosure. FIG. 1 shows an example of a conventional stoma appliance. FIG. 10 is a cross-sectional view showing an example of the configuration of the stoma appliance shown in FIG.

The following describes the embodiments of the present disclosure with reference to the drawings. Note that the embodiments shown below are examples of the embodiments of the present disclosure, and the present disclosure is not to be interpreted as being limited to these embodiments. In this specification, terms such as "substrate", "sheet", and "film" are not distinguished from each other based only on the difference in name. For example, "substrate" is a concept that includes members that can be called sheets and films. Furthermore, terms such as "vertical" and values of length and angle that specify shapes and geometric conditions and their degrees, as used in this specification, are not bound by strict meanings, but are interpreted to include a range in which similar functions can be expected. In addition, in the drawings referred to in this embodiment, the same or similar symbols are used for the same parts or parts having similar functions, and repeated explanations may be omitted. In addition, the dimensional ratios of the drawings may differ from the actual ratios for the convenience of explanation, and some of the configurations may be omitted from the drawings.

<Sound absorbing sheet>
Fig. 1 is a cross-sectional view showing an example of the sound-absorbing sheet of the present disclosure, and Fig. 2 is a cross-sectional view showing another example of the sound-absorbing sheet of the present disclosure.

In the example shown in FIG. 1, the sound absorbing sheet 1 has a laminated structure in which an adhesive layer 12 and a foamed adsorption sound absorbing layer 13 are laminated in this order on a substrate 11. The sound absorbing sheet of the present disclosure may also have a laminated structure in which an adhesive layer 12, a foamed adsorption sound absorbing layer 13, and a release material 21 are laminated in this order on a substrate 11, as in the sound absorbing sheet 2 shown in FIG. 2.

Here, the sound absorbing sheet 2 shown in Fig. 2 has a configuration in which a release material 21 is provided on the foamed adsorbent sound absorbing layer 13 of the sound absorbing sheet 1 shown in Fig. 1, and by peeling off the release material 21 when attaching the sound absorbing sheet to an adherend, it becomes the sound absorbing sheet 1 shown in Fig. 1. In other words, the sound absorbing sheet 2 shown in Fig. 2 can be said to be in a state before use of the sound absorbing sheet 1 shown in Fig. 1.
Hereinafter, each of the components constituting the sound-absorbing sheet of the present disclosure will be described.

(Substrate)
The substrate 11 holds the adhesive layer 12 and the foamed adsorption sound absorbing layer 13. In the sound absorbing sheet 1, the substrate 11 and the foamed adsorption sound absorbing layer 13 are firmly bonded by the adhesive layer 12, so that even if the sound absorbing sheet 1 is repeatedly attached to and peeled off from an adherend, the substrate 11 and the foamed adsorption sound absorbing layer 13 do not become separated from each other. Here, the substrate 11 preferably has flexibility so that it can follow the surface shape of the adherend when attached or peeled off.

In the sound-absorbing sheet of the present disclosure, as described later in the manufacturing method of the foamed adsorption sound-absorbing layer, the foamed adsorption sound-absorbing layer 13 that has been subjected to the heat drying process is bonded to the substrate 11 via the adhesive layer 12. Examples of the substrate 11 include nonwoven fabrics with sound-absorbing and vibration-damping properties, and polymeric porous bodies such as urethane and polyester.

The total thickness of the substrate 11 is preferably 5 mm or more and 100 mm or less, more preferably 5 mm or more and 30 mm or less. If the total thickness of the substrate 11 is within the above range, it becomes a thin sound absorbing sheet, and can be used for various purposes where a thin sound absorbing sheet is required. In addition, the average density of the sound absorbing sheet is preferably 300 kg/m ³ or less, more preferably 1 kg/m ³ or more and 200 kg/m ³ or less, even more preferably 5 kg/m ³ or more and 150 kg/m ³ or less, particularly preferably 10 kg/m ³ or more and 100 kg/m ³ or less, and most preferably 20 kg/m ³ or more and 50 kg/m ³ or less.

[Nonwoven fabric]
The nonwoven fabric having sound absorption and vibration damping properties may be either a nonwoven fabric made of short fibers or a nonwoven fabric made of long fibers. For example, needle punched nonwoven fabric, water jet punched nonwoven fabric, melt blown nonwoven fabric, spun bonded nonwoven fabric, stitch bonded nonwoven fabric, etc. are used. Among them, needle punched nonwoven fabric or water jet punched nonwoven fabric is preferred, and needle punched nonwoven fabric is particularly preferred. Miscellaneous felt can also be used as the nonwoven fabric. Its basis weight is preferably in the range of 150 g/m ² to 800 g/m ² , and its bulk density is preferably 0.01 g/cm ³ to 0.2 g/cm ³ .

The cross-sectional shape of the fibers constituting the nonwoven fabric is not particularly limited, and may be a perfect circle or an irregular cross-sectional shape. For example, it may be an ellipse, hollow, X-shaped, Y-shaped, T-shaped, L-shaped, star-shaped, leaf-shaped (e.g., trefoil, tetralobe, pentacole, etc.), or other polygonal cross-sectional shape (e.g., triangular, rectangular, pentagonal, hexagonal, etc.).

The fibers constituting the nonwoven fabric may be natural or synthetic, but synthetic fibers are preferably used from the viewpoint of durability. Examples of such fibers include thermoplastic fibers such as polyester fibers, polyamide fibers (e.g., nylon fibers, etc.), acrylic fibers, and polyolefin fibers (e.g., polypropylene fibers, polyethylene fibers, etc.), and the above-mentioned fiber materials can be used which are manufactured according to known methods such as wet spinning, dry spinning, or melt spinning. Among them, polyester fibers, polypropylene fibers, and nylon fibers are preferred from the viewpoint of excellent durability and abrasion resistance. In particular, polyester fibers are most preferred from the viewpoints that the raw polyester can be easily recycled by thermal melting of used nonwoven fabric, it is economical, the texture of the nonwoven fabric is good, and it is easy to mold.

[Porous polymer]
Specific examples of the polymeric porous body include polyurethane foam, polystyrene foam, polyolefin (e.g., polyethylene, polypropylene) foam, ethylene-propylene-diene rubber (EPDM) foam, etc. As the porous structure of the polymeric porous body, any appropriate structure can be adopted depending on the purpose. Such a structure may be, for example, a closed cell structure in which each bubble formed by foaming is independent, or a continuous cell structure in which at least a part of the bubbles are continuous.

Polyurethane foam is composed of a porous elastic body made of polyurethane with multiple pores. The polyurethane that forms the matrix of the porous elastic body can be produced by polymerizing a polyol component and a polyisocyanate component.

The polyol component includes a high molecular weight polyol and a chain extender. Examples of high molecular weight polyols include polyether polyols such as polypropylene glycol, polytetramethylene glycol, and polymer polyols, adipate polyols, polyester polyols such as polycaprolactone polyols, polycarbonate polyols, and polyolefin polyols. Examples of chain extenders include low molecular weight diols such as ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, and 3-methyl-1,5-pentanediol.

The polyisocyanate component contains a polyisocyanate compound. Examples of polyisocyanates contained in the polyisocyanate component include aromatic isocyanates such as tolylene diisocyanate (TDI), diphenylmethane-4,4'-diisocyanate (MDI), xylylene diisocyanate (XDI), 1,5-naphthalene diisocyanate (NDI), and tetramethylxylylene diisocyanate (TMXDI), alicyclic isocyanates such as isophorone diisocyanate (IPDI) and hydrogenated xylylene diisocyanate (H6XDI), and aliphatic isocyanates such as hexamethylene diisocyanate (HDI), dimer acid diisocyanate (10-[5,6-dihexyl-2-(8-isocyanatooctyl)-3-cyclohexen-1-yl]-9-decenyl isocyanate), and norbornene diisocyanate (NBDI).

The polyol components may be used alone or in combination of two or more of the above. Similarly, the polyisocyanate components may be used alone or in combination of two or more of the above. As a precursor of polyurethane, a polyurethane water dispersion in which polyurethane formed from the polyol component and the polyisocyanate component is dispersed in an aqueous solvent may be used.

The porous elastomer can be formed, for example, as follows. Although not particularly limited, as an example, a method of forming the porous elastomer in an aqueous solvent using a water coagulation method in addition to the polyol component and the polyisocyanate component, a pore-forming component, and other additives (such as surfactants) will be described.

First, prepare the polyol component, polyisocyanate component, pore-forming component, water-based solvent, and other additives.

As the pore-forming component, a pore-forming agent made of a water-soluble inorganic salt can be used. Examples of such inorganic salts include sodium salts and potassium salts. More specifically, examples include chlorides such as sodium chloride and potassium chloride, and sulfates such as sodium sulfate (mirabilite) and potassium sulfate (sulfuric acid).

When the pore-forming component dissolves in the polyurethane, cavities are formed where the pore-forming component was present. These cavities become the source of the pores in the porous elastic body. As an example, it is preferable that the pore-forming component at least partially contains a pore-forming agent with an average particle size of 50 μm or less. Also, in order to reduce the variation in the size of the pores formed, it is preferable to use a pore-forming component that contains a pore-forming agent with a narrow particle size distribution. The pore size is related to sound absorption properties and preferably contains an average particle size of 100 μm or more. Pore sizes ranging from 30 μm to 2000 μm are mixed.

On the other hand, as the pore size becomes smaller, the strength and elasticity of the foam tend to decrease. Therefore, it is preferable for the porous elastic body to contain some large pores. The thickness of the skeletal structure of the foam surrounding the large pores tends to be thicker than the thickness of the skeletal structure surrounding the small pores. Such a thick skeletal structure acts like a pillar supporting the internal structure of the foam. This increases the strength and elasticity of the foam, making it less likely to collapse.

Therefore, the pore-forming component preferably contains both a first pore-forming agent having an average particle size of 50 μm or less and a second pore-forming agent having an average particle size of more than 50 μm. The ratio of the second pore-forming material to the total amount of the pore-forming components can be appropriately selected taking into consideration the required strength and elastic modulus. The ratio is, for example, 40% by mass or less, 30% by mass or less, 20% by mass or less, or 10% by mass or less out of 100% by mass of the pore-forming components.

The amount of the pore-forming component is preferably 100 to 2000 parts by weight, more preferably 500 to 1500 parts by weight, per 100 parts by weight of the solid content of the polyurethane to be formed. If the amount of the pore-forming component is too small, the pore-forming material does not spread throughout the polyurethane, and the distribution of the pores tends to be uneven. If the amount of the pore-forming component is too large, the strength of the porous elastic body tends to decrease. When using 100 to 2000 parts by weight of the pore-forming agent per 100 parts by weight of the solid content of the polyurethane to be formed, it is preferable because the distribution of the pores formed in the porous elastic body and the strength and elasticity of the porous elastic body are appropriate.

The aqueous solvent may be water or a mixture of water and a water-soluble solvent. Examples of water-soluble solvents include alcohol-based solvents such as methanol, ethanol, and ethylene glycol. From the standpoint of low environmental impact and cost, it is preferable to use water alone as the aqueous solvent.

The amount of the water-based solvent (preferably water) is preferably 10 parts by mass or more and 300 parts by mass or less, and more preferably 10 parts by mass or more and 200 parts by mass or less, per 100 parts by mass of the solid content of the polyurethane to be formed. This range is preferable in that the viscosity of the polyurethane-containing solution is appropriate and the resulting polyurethane has appropriate strength and elasticity.

Additives of the above other additives include surfactants such as sorbitan fatty acid esters, polyglycerin fatty acid esters, and polyethylene glycol oleates. The surfactant is preferably present in an amount of 5 parts by mass or more and 50 parts by mass or less per 100 parts by mass of the solid content of the polyurethane to be formed.

Using these raw materials, a polyurethane porous elastic body is formed by a method called the water coagulation method. First, the above components are charged into a kneading device and kneaded. For kneading, a kneader, an auger kneader, a Banbury mixer, a screw extruder, etc. can be used.

After kneading, the resulting mixture is degassed. After degassing, the mixture is molded into the desired shape. There are no particular limitations on the degassing method. For example, degassing under reduced pressure may be performed using a vented extruder. There are also no particular limitations on the molding method. For example, a molding die (T-die) corresponding to the desired shape may be connected to the vented extruder used for degassing under reduced pressure, and molding may be performed.

After molding, the resulting molded product is placed in water or an aqueous solution. This operation replaces the solvent with water and precipitates polyurethane. This operation is called water coagulation. There are no particular restrictions on the procedure up to the point where the molded product is placed, but for example, a method can be used in which, in the molding process, the kneaded material is extruded and filled into a box-shaped object with an open top using a punching metal made of stainless steel 304 or the like, molding is performed, and the resulting molded product is placed in water or an aqueous solution.

After the water coagulation operation, the pore-forming agent, which is made of a water-soluble inorganic salt, is removed by dissolving it in water. The method is not particularly limited, but examples include the following method. The molded product of the kneaded material in a container is left in warm water to dissolve most of the pore-forming agent. The molded product is then placed in a general washing machine or the like and washed in water at 20°C to 80°C for 15 to 90 minutes. During washing, it is preferable to replace the washing water as necessary.

The molded body thus obtained is then dried. To prevent deterioration of the polyurethane due to heat, the body is dried, for example, in a dryer at 110°C or below. In this way, a foam consisting of a polyurethane porous elastic body is obtained.

The size and distribution of the pores in the porous elastomer can be controlled by adjusting the ratio of the polyol and polyurethane components that make up the polyurethane, the mixing conditions and mixing time, the type and amount of additives, the amount, particle size, and particle size distribution of the pore-forming agent, etc. In particular, the ease with which pores are formed varies depending on the type of polyurethane component. Therefore, various conditions are appropriately adjusted depending on the properties of the polyurethane component and the required properties. The state of pore formation can also be changed by adjusting the type and amount of surfactant.

(Adhesive layer)
In the sound absorbing sheet 1, the adhesive layer 12 bonds the base material 11 and the foamed adsorption sound absorbing layer 13 at a temperature of 130° C. or higher and 200° C. or lower. The presence of the adhesive layer 12 prevents the base material 11 and the foamed adsorption sound absorbing layer 13 from becoming separated from each other even when the sound absorbing sheet 1 is repeatedly attached to and peeled off from an adherend.
Furthermore, as described below, the sound-absorbing sheet of the present disclosure has an adhesive layer 12, which makes it unaffected by the temperature (130°C or higher and 200°C or lower) of the heating and drying process in forming the foamed adsorption sound-absorbing layer 13.

Existing adhesives such as acrylic, epoxy, and olefin adhesives can be used as the material for forming the adhesive layer 12. In particular, an acrylic adhesive that can be bonded at room temperature regardless of the substrate can be suitably used.
This acrylic adhesive contains a (meth)acrylic acid ester copolymer as the main component, a rosin ester tackifying resin, and an isocyanate crosslinking agent to crosslink the (meth)acrylic acid ester copolymer.
Here, the term "(meth)acrylic acid ester polymer" refers to a polymer obtained using at least one of an acrylic acid ester and a methacrylic acid ester as a monomer.

[(Meth)acrylic acid ester copolymer]
The (meth)acrylic acid ester polymer preferably contains, as monomer units, a (meth)acrylic acid alkyl ester having an alkyl group with a carbon number of 2 to 20, and a monomer having a reactive functional group in the molecule (reactive functional group-containing monomer), which allows the polymer to exhibit desirable adhesiveness.

As the (meth)acrylic acid alkyl ester having an alkyl group with 2 to 20 carbon atoms, those having a glass transition temperature (Tg) of -40°C or lower as a homopolymer (hereinafter sometimes referred to as "specific acrylates") are preferred. By including such specific acrylates as constituent monomer units, excellent flex resistance can be maintained.

As the specific acrylate, for example, n-butyl acrylate (Tg-55°C), n-octyl acrylate (Tg-65°C), isooctyl acrylate (Tg-58°C), 2-ethylhexyl acrylate (Tg-70°C), isononyl acrylate (Tg-58°C), isodecyl acrylate (Tg-60°C), isodecyl methacrylate (Tg-41°C), n-lauryl methacrylate (Tg-65°C), tridecyl acrylate (Tg-55°C), tridecyl methacrylate (-40°C), etc. are preferably used. Among them, from the viewpoint of more effectively reducing the storage modulus, it is more preferable that the specific acrylate has a homopolymer Tg of -45°C or less, and particularly preferably -50°C or less. Specifically, n-butyl acrylate and 2-ethylhexyl acrylate are particularly preferable.
These may be used alone or in combination of two or more. The alkyl group in the (meth)acrylic acid alkyl ester having from 2 to 20 carbon atoms refers to a linear, branched or cyclic alkyl group.

The (meth)acrylic acid ester polymer preferably contains 60% by mass or more of the specific acrylate as a monomer unit, more preferably 80% by mass or more, and particularly preferably 90% by mass or more.

In addition, the (meth)acrylic acid ester polymer preferably contains 99.9% by mass or less of the specific acrylate as a monomer unit, more preferably 99% by mass or less, and particularly preferably 98% by mass or less. By containing 99.9% by mass or less of the specific acrylate, it is possible to introduce a suitable amount of other monomer components (particularly reactive functional group-containing monomers) into the (meth)acrylic acid ester polymer.

The (meth)acrylic acid ester polymer contains a reactive functional group-containing monomer as a monomer unit, and reacts with a crosslinking agent (described below) via the reactive functional group derived from the reactive functional group-containing monomer, thereby forming a crosslinked structure (three-dimensional network structure) and obtaining the desired cohesive strength.

As the reactive functional group-containing monomer contained as a monomer unit in the (meth)acrylic acid ester polymer, a monomer having a hydroxyl group in the molecule (hydroxyl group-containing monomer), a monomer having an amino group in the molecule (amino group-containing monomer), etc. are preferred. Among these, a hydroxyl group-containing monomer is particularly preferred.

Examples of the hydroxyl group-containing monomer include (meth)acrylic acid hydroxyalkyl esters such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 3-hydroxybutyl (meth)acrylate, and 4-hydroxybutyl (meth)acrylate. Among them, at least one of 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, 3-hydroxypropyl acrylate, and 4-hydroxybutyl acrylate is preferred in terms of the glass transition temperature (Tg), the reactivity of the hydroxyl group in the resulting (meth)acrylic acid ester polymer with the crosslinking agent, and copolymerizability with other monomers. These may be used alone or in combination of two or more.

The hydroxyl value of the (meth)acrylic acid ester copolymer is not particularly limited, but from the viewpoint of suppressing the occurrence of separation between the adhesive layer 12 and the substrate 11, and between the adhesive layer 12 and the foamed adsorption sound absorbing layer 13 when the sound absorbing sheet is repeatedly bent, the lower limit is preferably 5 mgKOH/g or more, more preferably 10 mgKOH/g or more. On the other hand, the upper limit is preferably 100 mgKOH/g or less, more preferably 90 mgKOH/g or less.

The (meth)acrylic acid ester polymer preferably contains 0.1% by mass or more of reactive functional group-containing monomer as a monomer unit, more preferably 0.5% by mass or more, and particularly preferably 1% by mass or more. The (meth)acrylic acid ester polymer preferably contains 30% by mass or less of reactive functional group-containing monomer as a monomer unit, more preferably 20% by mass or less, and particularly preferably 8% by mass or less.

The polymerization mode of the (meth)acrylic acid ester polymer may be a random copolymer or a block copolymer.

The lower limit of the weight average molecular weight of the (meth)acrylic acid ester polymer is preferably at least 200,000, more preferably at least 300,000, and particularly preferably at least 400,000. When the lower limit of the weight average molecular weight of the (meth)acrylic acid ester polymer is the above-mentioned or more, problems such as seepage of the adhesive during processing of the sound absorbing sheet are suppressed.
In this specification, the weight average molecular weight is a value measured by gel permeation chromatography (GPC) and converted into standard polystyrene.

The upper limit of the weight average molecular weight of the (meth)acrylic acid ester polymer is preferably 1,000,000 or less, more preferably 900,000 or less, and particularly preferably 800,000 or less. When the upper limit of the weight average molecular weight of the (meth)acrylic acid ester polymer is the above or less, the adhesion to the adherend and the storage modulus of the resulting sound absorbing sheet tend to fall within a suitable range.

[Rosin ester tackifier resin]
The rosin ester-based tackifying resin added to the acrylic adhesive that constitutes the adhesive layer 12 is a rosin ester-based tackifying resin which is an ester of a rosin-based tackifying resin such as gum rosin, wood rosin, or tall oil rosin, which mainly contains resin acids such as abietic acid, palustric acid, neoabietic acid, pimaric acid, isopimaric acid, or dehydroabietic acid, with various alcohols.

The content of the rosin ester tackifying resin in the acrylic adhesive constituting the adhesive layer 12 is preferably 1 part by weight or more and 40 parts by weight or less, more preferably 1.5 parts by weight or more and 35 parts by weight or less, and even more preferably 2 parts by weight or more and 30 parts by weight or less, relative to 100 parts by weight of the (meth)acrylic acid ester polymer. If the content is 1 part by weight or more, the bending resistance performance of the sound absorbing sheet is improved. On the other hand, by making the content 40 parts by weight or less, clouding of the sound absorbing sheet can be suppressed.

[Isocyanate-based crosslinking agent]
When an isocyanate-based crosslinking agent is added to the acrylic adhesive constituting the adhesive layer 12 and heated, the isocyanate-based crosslinking agent crosslinks the (meth)acrylic acid ester polymer to form a three-dimensional network structure.

The isocyanate-based crosslinking agent contains at least a polyisocyanate compound. Examples of the polyisocyanate compound include aromatic polyisocyanates such as tolylene diisocyanate, diphenylmethane diisocyanate, and xylylene diisocyanate, aliphatic polyisocyanates such as hexamethylene diisocyanate, alicyclic polyisocyanates such as isophorone diisocyanate and hydrogenated diphenylmethane diisocyanate, and biuret and isocyanurate forms thereof, as well as adducts which are reaction products with low-molecular active hydrogen-containing compounds such as ethylene glycol, propylene glycol, neopentyl glycol, trimethylolpropane, and castor oil.
Among these, from the viewpoint of reactivity with hydroxyl groups, trimethylolpropane-modified aromatic polyisocyanates, in particular trimethylolpropane-modified tolylene diisocyanate and trimethylolpropane-modified xylylene diisocyanate, are preferred.

The content of the isocyanate-based crosslinking agent in the acrylic adhesive constituting the adhesive layer 12 is preferably 0.01 parts by mass or more, more preferably 0.05 parts by mass or more, and even more preferably 0.1 parts by mass or more, per 100 parts by weight of the (meth)acrylic acid ester polymer. The content is also preferably 10 parts by mass or less, more preferably 8 parts by mass or less, and even more preferably 5 parts by mass or less.

[Other additives]
If necessary, various additives commonly used in acrylic adhesives, such as a silane coupling agent, an ultraviolet absorber, an antistatic agent, a tackifier, an antioxidant, a light stabilizer, a softener, a filler, and a refractive index adjuster, may be added to the acrylic adhesive constituting the adhesive layer 12.

(Foamed sound-absorbing layer)
The foamed sound-absorbing layer 13 is made of a foamed (meth)acrylic ester polymer. This foamed material can be obtained, for example, by mechanically foaming a (meth)acrylic ester polymer emulsion and then drying it by heating.
Mechanical foaming refers to dispersing and mixing air bubbles in an emulsion by mechanical treatment such as stirring and mixing the emulsion. By heating and drying, the dispersion medium contained in the mechanically foamed (meth)acrylic acid ester polymer emulsion is evaporated and removed.

The mechanically foamed (meth)acrylic acid ester polymer emulsion contains a (meth)acrylic acid ester polymer resin as a dispersoid, air bubbles, and a dispersion medium for dispersing these.
The (meth)acrylic acid ester polymer foam, which is a heat-dried product of the mechanically foamed (meth)acrylic acid ester polymer emulsion, contains the (meth)acrylic acid ester polymer resin and voids present in this resin. The foamed adsorption sound-absorbing layer 13 has these voids, and thus causes an adsorption phenomenon on the surface of the adherend when it is attached to the adherend. This phenomenon also acts to allow the foamed adsorption sound-absorbing layer 13 to stick to the adherend, i.e., to adhere.

In the manufacture of the foamed sound-absorbing layer 13, the foaming ratio is adjusted to be 2.0 times or more and 4.0 times or less.
If the foaming ratio is less than 2.0 times, the adhesive strength of the foamed adsorption sound-absorbing layer 13 to the substrate will be weak, and the sound-absorbing sheet 1 may not be able to maintain its adhesion to the substrate with sufficient adhesive strength.
Furthermore, if the expansion ratio exceeds 4.0 times, the adhesive strength of the foamed adsorption sound absorbing layer 13 to the adherend becomes too strong, and when the sound absorbing sheet 1 is peeled off from the adherend, the foamed adsorption sound absorbing layer 13 may tear off and remain on the adherend (a phenomenon known as "film residue"). If this film residue occurs, the foamed adsorption sound absorbing layer 13 is partially destroyed, that portion is lost, and it becomes impossible to peel it off again.

The (meth)acrylic acid ester polymer emulsion can be obtained, for example, by emulsion polymerization of one or more (meth)acrylic acid esters and, if necessary, other monomers other than the (meth)acrylic acid esters in a dispersion medium such as water in the presence of a polymerization initiator and, if necessary, an emulsifier or dispersion stabilizer.

Examples of (meth)acrylic acid esters include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, butyl (meth)acrylate, hexyl (meth)acrylate, heptyl (meth)acrylate, octyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, nonyl (meth)acrylate, decyl (meth)acrylate, dodecyl (meth)acrylate, octadecyl (meth)acrylate, cyclohexyl (meth)acrylate, isobornyl (meth)acrylate, dicyclopentanyl (meth)acrylate, phenyl (meth)acrylate, and (meth)acrylate. Examples of such esters include (meth)acrylic acid hydrocarbon esters such as benzyl acrylate and allyl (meth)acrylate, (meth)acrylic acid heteroatom-containing esters such as glycidyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, polyethylene glycol mono(meth)acrylate, glycerol mono(meth)acrylate, ethylene glycol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, neopentyl glycol di(meth)acrylate, and polypropylene glycol di(meth)acrylate.

Other monomers include, for example, unsaturated carboxylic acid compounds such as (meth)acrylic acid, crotonic acid, itaconic acid, maleic acid, fumaric acid, itaconic acid monoester, maleic acid monoester, maleic anhydride, itaconic anhydride, etc., aromatic vinyl compounds such as styrene and divinylbenzene, unsaturated nitrile compounds such as acrylonitrile, conjugated diene compounds such as butadiene and isoprene, diallyl phthalate, allyl glycidyl ether, etc.

Examples of the dispersion medium for the (meth)acrylic acid ester polymer emulsion include water, alcohols such as ethanol, ketones such as acetone, esters such as ethyl acetate, ethers such as dipropyl ether, and glycol ethers such as ethylene glycol monomethyl ether. Of these, water is preferred.

The (meth)acrylic acid ester polymer emulsion may contain, for example, a surfactant, a silicone compound, etc. One type (or two or more types) of (meth)acrylic acid ester polymer emulsion may be used.

The lower limit of the glass transition temperature (Tg) of the resin constituting the (meth)acrylic acid ester polymer emulsion is preferably -55°C, more preferably -50°C, even more preferably -45°C, and particularly preferably -40°C. The upper limit of the above Tg is preferably 30°C, more preferably 20°C, even more preferably 10°C, and particularly preferably 0°C. By setting the Tg of the (meth)acrylic acid ester polymer within the above range, the adhesive properties of the foamed adsorption sound absorbing layer 13 can be further improved.

The lower limit of the average particle size of the dispersed matter of the (meth)acrylic acid ester polymer emulsion is preferably 50 nm, more preferably 70 nm, and even more preferably 80 nm. The upper limit of the average particle size is preferably 600 nm, more preferably 500 nm, and even more preferably 400 nm. The average particle size is, for example, the volume-based median size measured by laser diffraction particle size distribution measurement.

The thickness of the foamed sound-absorbing layer 13 is preferably in the range of 150 μm to 5000 μm. By setting the thickness of the foamed sound-absorbing layer 13 in the above range, the sound absorbing properties and productivity of the foamed sound-absorbing layer 13 can be improved.
The "thickness" of the foamed sound-absorbing layer 13 means the arithmetic mean value of thicknesses measured at three different points within an area of 10 cm square of the foamed sound-absorbing layer 13.

The weight of the foamed sound absorbing layer 13 is preferably in the range of 60 g/ ^m2 to 600 g/ ^m2 . If it is less than 60 g/ ^m2 , it will not contribute to sound absorption, and if it exceeds 600 g/ ^m2 , production will become unstable and costs will increase.
The "weight" of the foamed sound-absorbing layer 13 refers to the weight per unit area of the foamed sound-absorbing layer 13, and is usually expressed in grams per square ^meter .

<Method of manufacturing foamed sound absorbing layer>
Next, a method for producing the foamed adsorption sound absorbing layer 13 will be described. The method for producing the foamed adsorption sound absorbing layer 13 includes a step of mechanically foaming a (meth)acrylic acid ester polymer emulsion (hereinafter also referred to as a "mechanical foaming step"), a step of coating one surface of a release material with the mechanically foamed (meth)acrylic acid ester polymer emulsion obtained by the mechanical foaming step (hereinafter also referred to as a "coating step"), and a step of heating and drying the coating layer formed by the coating step (hereinafter also referred to as a "heat drying step"). Each step will be described below.

[Mechanical foaming process]
In this step, the (meth)acrylic acid ester polymer emulsion is mechanically foamed. Examples of the device used for mechanical foaming include a batch type foaming machine and a continuous type foaming machine. Examples of the gas introduced in the mechanical foaming include air, nitrogen, oxygen, etc.

During mechanical foaming, the (meth)acrylic acid ester polymer emulsion may be added with, for example, the tackifying resin (rosin ester-based tackifying resin) used in the adhesive layer 12, a thickener, a foam stabilizer, etc.

The conditions of the batch type foaming machine, such as the stirring speed and foaming time, are appropriately selected so that the density of the resulting mechanically foamed (meth)acrylic acid ester polymer emulsion is the desired value. The stirring speed of the batch type foaming machine can be, for example, in the range of 100 rpm to 300 rpm. The foaming time of the batch type foaming machine can be, for example, in the range of 1 minute to 60 minutes.

The conditions of the continuous foaming machine, such as the liquid flow rate, gas flow rate, and mixer rotation speed, are appropriately selected so that the density, flow rate, etc. of the resulting mechanically foamed (meth)acrylic acid ester polymer emulsion are the desired values.

[Coating process]
In this step, the mechanically foamed (meth)acrylic acid ester polymer emulsion obtained in the mechanical foaming step is applied to one surface of a predetermined release material. As described later, in the present disclosure, the release material 21 or the like can be used as the substrate to which the mechanically foamed (meth)acrylic acid ester polymer emulsion is applied. Details will be described later in the method for producing an adsorption sheet.

Coating methods include, for example, the casting head method, roll coating method, air knife coating method, gravure roll coating method, doctor roll coating method, doctor knife coating method, curtain flow coating method, spray method, brush coating method, etc.

The thickness of the coating layer to be formed is appropriately selected so that the thickness of the foam of the (meth)acrylic acid ester polymer formed by heat drying is the desired value. The thickness of the coating layer to be formed can be, for example, in the range of 80 μm to 8000 μm.

[Heat drying process]
In this process, the coating layer formed in the coating process is heated and dried. That is, the dispersion medium in the mechanically foamed (meth)acrylic acid ester polymer emulsion constituting the coating layer is evaporated by heating. As a result, a (meth)acrylic acid ester polymer foam, which is a heat-dried product of the mechanically foamed (meth)acrylic acid ester polymer emulsion, is formed on the release material. The formed (meth)acrylic acid ester polymer foam contains the (meth)acrylic acid ester polymer resin and voids present in this resin.

Devices for heating and drying the coating layer include, for example, ovens, hot plates, hot air dryers, and hot air circulation ovens.

The conditions of the heat drying, such as temperature and time, are appropriately selected so that the dispersion medium is not substantially contained in the foam of the (meth)acrylic acid ester polymer that is formed. The heat drying is carried out at a temperature of 130° C. or more and 200° C. or less. Of these, a temperature of 140° C. or more and 150° C. or less is preferably used.
From the viewpoint of improving productivity, the heat drying time is preferably 60 minutes or less, and more preferably 40 minutes or less.

(Release agent)
The sound-absorbing sheet of the present disclosure before being attached to an adherend (i.e., the sound-absorbing sheet before use) preferably has a configuration having a release material 21 on a foamed adsorbent sound-absorbing layer 13, for example, as in the sound-absorbing sheet 2 shown in Figure 2.

The release material 21 protects the foamed, adsorbent, sound-absorbing layer 13 of the sound-absorbing sheet before use, and prevents the foamed, adsorbent, sound-absorbing layer 13 of the sound-absorbing sheet before use from sticking to other objects unintentionally.

Furthermore, as described below, in the manufacture of the sound-absorbing sheet of the present disclosure, when forming the foamed adsorption sound-absorbing layer 13, a release material 21 or the like can be used as a substrate to which the mechanically foamed (meth)acrylic acid ester polymer emulsion is applied.

Because the heating and drying temperature for forming the foamed adsorption sound absorbing layer 13 is high, when using a release material 21 as a substrate for coating the mechanically foamed (meth)acrylic acid ester polymer emulsion, it is necessary to select a release material with a melting point of 130°C or higher. For example, PET (thickness 12 μm to 70 μm) is preferably used as the release material.

On the other hand, in the sound-absorbing sheet of the present disclosure, as shown in the process of FIG. 5 used in the explanation of the manufacturing method of the sound-absorbing sheet described later, a process flow can be used in which a foamed adsorbent sound-absorbing layer 13 is first formed on a first release material 41 (FIG. 5(a)), a second release material 42 (corresponding to the release material 21 shown in FIG. 2) is then formed on the foamed adsorbent sound-absorbing layer 13 (FIG. 5(b)), and then the first release material 41 is peeled off to prepare a first laminate 31B (FIG. 5(c)).

In this case, a polyolefin film, which has a lower release performance than PET, is usually used as the material constituting the release material 21. This makes it possible to prevent the release material 21 from peeling off due to vibrations or the like during the distribution process of the sound absorbing sheet 2. Also, a polyolefin film is preferable from the viewpoint of cost.
As the polyolefin film, a film such as unstretched polypropylene, unstretched LDPE film, LLDPE film, etc. is selected. The thickness is selected from 20 μm to 80 μm, and preferably 30 μm to 50 μm.

<Method of manufacturing sound absorbing sheet>
(First embodiment)
FIG. 3 is a process diagram showing an example of a method for producing a sound absorbing sheet according to the present disclosure.
As described above, the manufacturing of the foamed adsorption sound absorbing layer 13 requires a heating and drying process carried out at 130° C. to 200° C. Therefore, when the mechanically foamed (meth)acrylic acid ester polymer emulsion is applied onto a substrate, the substrate is required to have heat resistance. More specifically, when the mechanically foamed (meth)acrylic acid ester polymer emulsion is applied onto a substrate, the substrate to be used is limited to a substrate having a melting point of 130° C. or more.
On the other hand, the applications of sound-absorbing sheets are expanding, and it is preferable that such temperature restrictions are not required for the base material of the sound-absorbing sheet. For example, it may be desirable for the base material of the sound-absorbing sheet to be made of a material having a melting point of less than 130°C.

Therefore, in this embodiment, a first laminate 31 is prepared in which a foamed adsorption sound absorbing layer 13 is formed on a heat-resistant release material 21, separate from the substrate 11, and the foamed adsorption sound absorbing layer 13 of the first laminate 31 is bonded to the substrate 11 via an adhesive layer 12 to produce the sound absorbing sheet of the present disclosure.

That is, the manufacturing method of the sound-absorbing sheet of this embodiment includes a laminate preparation process of preparing a first laminate 31 in which a foamed adsorption sound-absorbing layer 13 is laminated on a release material 21, and a second laminate 32 in which an adhesive layer 12 is laminated on a substrate 11, and a bonding process of opposing the foamed adsorption sound-absorbing layer 13 of the first laminate 31 to the adhesive layer 12 of the second laminate 32 and bonding them together.
This will be explained in detail below with reference to FIG.

[Laminate preparation process]
In the manufacturing method of the sound-absorbing sheet of this embodiment, as shown in Figure 3 (a), first, a first laminate 31 in which a foamed adsorption sound-absorbing layer 13 is laminated on a release material 21, and a second laminate 32 in which an adhesive layer 12 is laminated on a base material 11 are prepared.

Here, in the first laminate 31, a mechanically foamed (meth)acrylic acid ester polymer emulsion is applied to one surface of the release material 21 in the same manner as in the manufacturing method of the foamed adsorption sound absorbing layer 13 described above, and then heated and dried to form the foamed adsorption sound absorbing layer 13 on the release material 21. The heating and drying temperature is 130°C or higher and 200°C or lower. Of these, a temperature of 140°C or higher and 150°C or lower is preferably used.

On the other hand, in the first laminate 31, an acrylic adhesive layer in the form of a so-called double-sided tape, with both sides protected by a release film, is used as the adhesive layer 12, and the release film on one side is peeled off and the adhesive is bonded to the substrate 11, and then the release film on the remaining side is peeled off to obtain the first laminate 31.

[Lamination process]
3B, the foamed sound-absorbing layer 13 of the first laminate 31 and the adhesive layer 12 of the second laminate 32 are placed opposite each other and bonded together. For example, a vacuum lamination technique can be used for this bonding step.
As a result, as shown in FIG. 3(c), the sound absorbing sheet 2 having the structure shown in FIG. 2 can be obtained.

Here, the release material 21 is required to have a melting point of 130°C or higher in order to heat-dry the mechanically foamed (meth)acrylic acid ester polymer emulsion. The melting point of the release material 21 may be equal to or higher than the heat-drying temperature. Here, since the heat-drying temperature is 130°C or higher and 200°C or lower, the upper limit of the melting point of the release material 21 may be 200°C.

The foamed sound-absorbing layer 13 is bonded to the substrate 11 via an adhesive layer 12 .
Therefore, adhesion between the foamed adsorption sound-absorbing layer 13 and the substrate 11 can be achieved by adjusting the adhesive strength of the adhesive layer 12, and the removability of the foamed adsorption sound-absorbing layer 13, i.e., the two performances of adhesion to the adherend and removability, can be adjusted separately from the adhesion to the substrate 11. For example, the adhesive strength of the adhesive layer 12 can be increased, and even if this adhesive strength is excessive, it is acceptable. And, with the foamed adsorption sound-absorbing layer 13, an optimal balance between adhesion and removability can be selected according to the adherend and the application, without being aware of the substrate 11.
Therefore, according to the present disclosure, it is possible to provide a sound-absorbing sheet that has both good adhesion to an adherend and good releasability.

Second Embodiment
Fig. 4 is a process diagram showing another example of the method for producing a sound absorbing sheet according to the present disclosure, and Fig. 5 is a diagram for explaining the first laminate shown in Fig. 4 .
This will be described in detail below with reference to FIG. 4 and FIG. 5.

[Laminate preparation process]
In the manufacturing method of the sound-absorbing sheet of this embodiment, as shown in Figure 4 (a), first, a first laminate 31A is prepared in which a foamed adsorption sound-absorbing layer 13 is laminated on a first release material 41, and a second release material 42 is laminated on the foamed adsorption sound-absorbing layer 13, and a second laminate 32 is prepared in which an adhesive layer 12 is laminated on a substrate 11.

Here, in preparing the first laminate 31A, first, as shown in FIG. 5(a), in the same manner as in the manufacturing method of the foamed adsorption sound absorbing layer 13 described above, a mechanically foamed (meth)acrylic acid ester polymer emulsion is applied to one surface of the first release material 41, and then heated and dried to form the foamed adsorption sound absorbing layer 13 on the first release material 41. The heating and drying temperature is 130°C or higher and 200°C or lower. Of these, a temperature of 140°C or higher and 150°C or lower is preferably used.

Therefore, the first release material 41 is required to have a melting point of 130°C or higher in order to heat-dry the mechanically foamed (meth)acrylic acid ester polymer emulsion. The melting point of the first release material 41 only needs to be equal to or higher than the heat-drying temperature. Here, since the heat-drying temperature is 130°C or higher and 200°C or lower, the upper limit of the melting point of the first release material 41 may also be 200°C.

As described below, the first release material 41 is peeled off from the heated and dried foamed adsorbent sound absorbing layer 13. Therefore, an easy-to-peel layer made of silicone or the like may be provided on the surface of the first release material 41 (more specifically, the surface to which the mechanically foamed (meth)acrylic acid ester polymer emulsion is applied) in order to facilitate peeling.

Next, as shown in Fig. 5(b), a second release material 42 is laminated on the heated and dried foamed adsorbent sound absorbing layer 13. In this way, a first laminate 31A shown in Fig. 4(a) is prepared.
Here, since the foamed sound-absorbing layer 13 has already been heated and dried, the second release material 42 is not heated.

Next, as shown in FIG. 5(c), the first release material 41 is peeled off from the first laminate 31A. More specifically, the first release material 41 is peeled off at the interface between the foamed adsorption sound absorbing layer 13 of the first laminate 31A and the first release material 41. This results in a first laminate 31B with the foamed adsorption sound absorbing layer 13 exposed.

[Lamination process]
4(b), the first laminate 31A is peeled off from the first release material 41 to obtain a first laminate 31B, and the exposed foamed adsorbent sound absorbing layer 13 of the first laminate 31B is placed opposite the adhesive layer 12 of the second laminate 32, and the two are bonded together. For example, a vacuum lamination technique can be used for this bonding step.
As a result, as shown in Fig. 4(c), it is possible to obtain the sound absorbing sheet 2 having the configuration shown in Fig. 2. Here, in this embodiment, the second release material 42 of the sound absorbing sheet 2 shown in Fig. 4(c) corresponds to the release material 21 of the sound absorbing sheet 2 having the configuration shown in Fig. 2.

<Stoma appliance>
Next, the stoma appliance of the present disclosure will be described. The stoma appliance of the present disclosure is a stoma appliance having the above-mentioned sound-absorbing sheet. Here, first, the configuration of a conventional stoma appliance will be described with reference to Figs. 9 and 10, and then the configuration of the stoma appliance of the present disclosure will be described with reference to Figs. 6 to 8.

Patients who have had a stoma created as an artificial anus wear a stoma appliance. When wearing the stoma appliance, waste material discharged from the stoma is stored in the pouch of the stoma appliance. The basic components of this stoma appliance include a base plate that adheres to the skin around the stoma, and a pouch that is connected to the base plate and stores waste material from the stoma.

Fig. 9 is a diagram showing an example of a conventional stoma appliance, in which Fig. 9(a) is a schematic plan view of the stoma appliance 200 as seen from the side where it is attached to the human body, and Fig. 9(b) is a schematic plan view of the stoma appliance 200 as seen from the outside (i.e., the side opposite to the side where it is attached to the human body).
Moreover, Fig. 10 is a diagram showing an example of a cross-sectional configuration of the stoma appliance 200 shown in Fig. 9. Here, Fig. 10(a) corresponds to a schematic plan view of Fig. 9(b), and Fig. 10(b) corresponds to a cross-sectional view taken along line Z-Z of Fig. 10(a).

As shown in Figures 9 and 10, the stoma appliance 200 includes a base plate 211 that is adhered to the skin around the stoma, and a pouch 213 that is connected to the base plate 211 and that contains waste from the stoma.

The base plate 211 has a stoma hole 212 in the approximate center, and the wearer wears the stoma appliance 200 by inserting his or her own stoma into the stoma hole 212. The base plate 211 has an adhesive layer on the surface facing the human body, and the stoma appliance 200 is worn so that no gaps are created between the adhesive layer of the base plate 211 and the skin around the stoma.

The pouch 213 is connected to the base plate 211 so that there is no gap between them, and contains waste from the wearer's stoma so that it does not leak from the pouch 213.
The pouch 213 has an outlet 214 on its underside (more specifically, on the ground side when the wearer wearing the stoma appliance 200 is standing upright) for discharging the contained waste from the pouch 213. Except when discharging, this outlet 214 is closed and waste from the stoma is stored in the pouch 213.

The main method of closing the outlet 214 is sealing with a clip (closure). For example, the wearer folds the pouch 213 near the outlet 214 and clips it in place to seal the outlet 214. There are also types in which a cap is provided on the outlet.

The stoma appliance 200 shown in Figures 9 and 10 is a so-called one-piece type stoma appliance in which the base plate 211 and pouch 213 are integrated. In addition, there are also so-called two-piece type stoma appliances in which the base plate and pouch are separable.

Next, the configuration of the stoma appliance of the present disclosure will be described.
Fig. 6 is a diagram showing an example of a stoma appliance of the present disclosure, in which Fig. 6(a) is a schematic plan view of the stoma appliance 101 as viewed from the side where it is attached to the human body, and Fig. 6(b) is a schematic plan view of the stoma appliance 101 as viewed from the outside (i.e., the side opposite to the side where it is attached to the human body).
Moreover, Fig. 7 is a diagram showing an example of a cross-sectional configuration of the stoma appliance 101 shown in Fig. 6. Here, Fig. 7(a) corresponds to a schematic plan view of Fig. 6(b), and Fig. 7(b) corresponds to a cross-sectional view taken along line A-A of Fig. 7(a).

As shown in Figures 6 and 7, the stoma appliance 101 includes a base plate 111 that is adhered to the skin around the stoma, a pouch 113 that is connected to the base plate 111 and that contains waste from the stoma, and a sound-absorbing sheet 1 that is attached to the surface of the pouch 113.

This sound-absorbing sheet 1 is provided to suppress noise emitted from the stoma, and has the same laminated structure as the sound-absorbing sheet 1 shown in Figure 1 as a basic configuration. The other components that make up the stoma appliance 101 (e.g., the base plate 111 and the pouch 113) can be the same as those used in conventional stoma appliances.

In the stoma appliance 101 illustrated in Figures 6 and 7, the sound absorbing sheet 1 is removably attached to the surface of the pouch 113 via the foamed adsorption sound absorbing layer 13. Therefore, for example, when taking a bath, the sound absorbing sheet 1 can be easily removed from the stoma appliance 101, eliminating the problem of the sound absorbing sheet 1 getting wet. The removed sound absorbing sheet 1 can be easily attached back to the stoma appliance 101 via the foamed adsorption sound absorbing layer 13, and by attaching the sound absorbing sheet 1, the sound emitted from the stoma can be suppressed again.

The sound absorbing sheet 1 is attached to the outer surface of the pouch 113 opposite the side connected to the base plate 111, and is preferably attached in a position that covers the stoma hole 112 provided in the base plate 111 when viewed from a direction perpendicular to the base plate 111 (for example, in the planar state shown in FIG. 6(b) or FIG. 7(a)). In such a position, the sound absorbing sheet 1 is positioned directly above the stoma inserted into the stoma hole 112, and sound emitted from the stoma can be effectively suppressed.

It is known that sounds emitted from a stoma are usually generated involuntarily by the wearer and that the wearer cannot control their generation. However, the sound absorbing effect of the sound absorbing sheet 1 can be further increased by the wearer consciously pressing the sound absorbing sheet 1 from the outside with their hand beforehand, such as after a meal, when sounds are likely to be emitted from the stoma. In other words, by pressing the sound absorbing sheet 1 tightly against the stoma appliance 101 with their hand, sound leakage from the sides of the sound absorbing sheet 1 can be prevented.

The base plate 111 of the stoma appliance 101 has a stoma hole 112 in the approximate center, and the wearer wears the stoma appliance 101 by inserting his or her own stoma into the stoma hole 112. The base plate 111 has an adhesive layer on the surface facing the human body, and the stoma appliance 101 is worn so that no gaps are created between the adhesive layer of the base plate 111 and the skin around the stoma.

The pouch 113 is connected to the base plate 111 so that there is no gap between them, and contains waste from the wearer's stoma so that it does not leak from the pouch 113.
The pouch 113 has an outlet 114 on its underside (more specifically, on the ground side when the wearer wearing the stoma appliance 101 is standing upright) for discharging the contained waste from the pouch 113. Except when discharging, this outlet 114 is closed and waste from the stoma is stored in the pouch 113.

The method of closing the outlet 114 mainly involves sealing with a clip (closure). For example, the wearer folds the pouch 113 near the outlet 114 and clips it in place to seal the outlet 114. There are also types in which a cap is provided on the outlet.

Note that in Figures 6 and 7, the stoma appliance 101 is illustrated as a so-called one-piece stoma appliance in which the base plate 111 and the pouch 113 are integrated, but the stoma appliance of the present disclosure may be a so-called two-piece stoma appliance in which the base plate and the pouch are separable.

(Sound absorbing sheet type)
Next, a preferred embodiment of the sound-absorbing sheet used in the stoma appliance of the present disclosure will be described.

The sound-absorbing sheet used in the stoma appliance of the present disclosure has, as a basic configuration, the laminated configuration of the sound-absorbing sheet 1 shown in Fig. 1. However, as a detailed configuration, as shown in Fig. 8, the base material 11 has a laminated configuration in which two layers, a first base material layer 121A and a second base material layer 121B, are laminated, and the first base material layer 121A has an opening 125A at the approximate center and a cutout portion 125B at a part of the outer periphery of the first base material layer 121A, and this cutout portion 125B is preferably connected to the opening 125A. An adhesive layer may be provided between the first base material layer 121A and the second base material layer 121B.
As described above, the sound absorbing sheet 120 shown in Fig. 8 has a cutout 125B in part of the outer periphery of the first base material layer 121A, and this cutout 125B is connected to the opening 125A. Here, Fig. 8(a) is a plan view of the sound absorbing sheet 120 seen from the side of the first base material layer 121A, and Fig. 8(b) corresponds to a cross-sectional view taken along line B-B in Fig. 8(a).
In FIG. 8( a), the opening 125A has a circular shape with a diameter D1 (more specifically, the shape of the area surrounded by the major arc from point P1 to point P4 in the figure and the straight line (chord) connecting point P1 and point P4), and the cutout portion 125B has a trapezoidal shape (more specifically, the shape of the area surrounded by the straight line connecting point P1 and point P2, the minor arc connecting point P2 and point P3, the straight line connecting point P3 and point P4, and the straight line connecting point P4 and point P1).

The sound-absorbing sheet 120 shown in FIG. 8 has an opening 125A, so that the wearer of the stoma appliance of the present disclosure can more easily determine the attachment position of the sound-absorbing sheet 120 in the pouch 113 by aligning this opening 125A with the wearer's own stoma (convex shape) inserted into the stoma hole 112 of the base plate 111.

Furthermore, in the sound absorbing sheet 1 shown in FIG. 8, a cutout portion 125B is formed in part of the outer periphery of the first base layer 121A, and this cutout portion 125B is connected to the opening portion 125A.
Here, a portion of the outer periphery of the first base material layer 121A in which the cutout portion 125B is provided (i.e., the minor arc connecting points P2 and P3 in Figure 8 (a)) is located on the side of the outlet 114 in the stoma appliance 101 shown in Figures 6 and 7.
When the wearer attaches the sound-absorbing sheet 120 to the stoma appliance 101 shown in Figures 6 and 7, the wearer attaches the sound-absorbing sheet 120 so that a part of the outer periphery of the first base material layer 121A where the cutout portion 125B of the sound-absorbing sheet 120 is provided (i.e., the minor arc portion connecting points P2 and P3 in Figure 8(a)) is on the side of the outlet 114 of the stoma appliance 101.
In the stoma appliance 101 equipped with the sound-absorbing sheet 120 shown in FIG. 8, waste from the stoma moves smoothly toward the outlet 114 along the opening 125A and the cutout 125B.

When the sound absorbing sheet 120 is attached to the stoma appliance 101, it is attached so that the side on which the opening 125A and the cutout 125B are provided (the Z direction side shown in FIG. 8(b)) faces the stoma appliance 101. Therefore, in the sound absorbing sheet 120, as shown in FIG. 8(b), the foamed adsorbent sound absorbing layer 13 is provided on the side of the first base material layer 121A (the Z direction side side shown in FIG. 8(b)) opposite the side on which the second base material layer 121B is located.

The hole diameter (circle equivalent hole diameter) of the opening 125A of the sound absorbing sheet 120 can be designed according to the stoma size of the wearer, but is preferably in the range of 30 mm or more and 50 mm or less.
It is preferable that the depth of the opening 125A of the sound absorbing sheet 120, i.e., the thickness (T1) of the first base material layer 121A, is greater than the thickness (T2 shown in Figure 8 (b)) of the second base material layer 121B. This is because it is possible to reduce the weight of the sound absorbing sheet 1 while effectively suppressing the sound emitted from the stoma. It is preferable that the depth of the opening 125A, i.e., the thickness (T1) of the first base material layer 121A, is in the range of 8 mm or more and 20 mm or less. It is preferable that the thickness (T2) of the second base material layer 121B is in the range of 5 mm or more and 10 mm or less.

The length L1 (the length of the straight line connecting points P1 and P4) and length L2 (the length of the straight line (chord) connecting points P2 and P3) of the cutout portion 125B of the sound-absorbing sheet 120 shown in Figure 8 (a) are determined taking into consideration the effect of suppressing the sound emitted from the stoma and the effect of smoothly moving excrement from the stoma toward the outlet 114.
For example, for the diameter (circle-equivalent diameter) D1 of the opening 125A shown in FIG. 8A, the lengths L1 and L2 can be in the range of 1/4×D1≦L1≦D1 and L1≦L2≦1.5×D1.

In the example shown in Fig. 8, a circular shape is exemplified as the planar shape of the sound absorbing sheet 120 (more specifically, the planar shape of the outer edge of the sound absorbing sheet 120), but the planar shape of the sound absorbing sheet of the present disclosure may be a circle, an ellipse, or any other shape formed of curved lines. It may also be a polygon such as a rectangle or a hexagon, or a polygon with curved corners. Furthermore, it may be any shape including straight lines and curved lines.
The sound-absorbing sheet preferably has an equivalent circle diameter in the range of 50 mm to 150 mm in order to more effectively achieve the effects of the present disclosure. The equivalent circle diameter is the diameter of a circle having the same area as the planar shape of the sound-absorbing sheet.
Furthermore, the sound absorbing sheet is required to be lightweight, preferably weighing 50 g or less per sheet.

At least a portion of the outer peripheral edge of the sound-absorbing sheet may be covered with any suitable layer as long as the effect of the present disclosure is not impaired. In addition, the outer peripheral edge of the sound-absorbing sheet may be covered by deforming the cross-sectional shape by pressing or the like.

The present disclosure will be explained in more detail below with reference to examples, but the present disclosure is in no way limited to these examples. The property values in the examples were measured by the following methods.

Example 1
The sound absorbing sheet of Example 1 was produced by the following procedure.

(Production of foamed sound-absorbing layer)
[Mechanical foaming process]
To the (meth)acrylic acid ester polymer emulsion, 1 mass % of a thickener and 4 mass % of a foam stabilizer ("Nopco DC-100-A" manufactured by San Nopco Ltd.) were added, and the mixture was uniformly stirred for 10 minutes with a stirrer. Next, foaming was carried out for 5 minutes at a stirring speed of 125 rpm in the air at room temperature of about 23°C using a batch type foaming machine ("Mixing Stirrer 5DM-r" manufactured by Dalton Co., Ltd., stirring tool: whipper) to obtain a mechanically foamed liquid of a (meth)acrylic acid ester polymer emulsion with a specific gravity of 0.3.

[Coating process]
As in the first laminate 31 shown in FIG. 3, a spacer frame (thickness: 150 μm) for setting the thickness was placed on the release PET as the release material 21, and the mechanical foaming liquid of the emulsion obtained above was poured in, and then a stainless steel ruler was used to remove excess foaming liquid along the spacer thickness, thereby obtaining a coating layer adjusted to a thickness of 150 μm.

[Heat drying process]
The laminate (coating layer/release material) including the coating layer formed above was heated and dried using a hot air circulation oven ("DH611" manufactured by Yamato Scientific Co., Ltd.) at a temperature of 150°C and a damper opening of 50%, to obtain a laminate having a foamed adsorption sound absorbing layer on the release PET. The thickness of the foamed adsorption sound absorbing layer formed was 150 μm, the expansion ratio was 2.0 times, and the basis weight of the foamed adsorption sound absorbing layer was 60 g/ ^m2 . The heat drying time was 40 minutes or less. Note that this heat drying time is the time required until the dispersion medium is substantially no longer observed in the foamed adsorption sound absorbing layer.

The thickness of the foamed sound-absorbing layer was determined by measuring a cross section cut out by a cutting machine with an optical microscope.
The expansion ratio of the foamed, adsorbent sound-absorbing layer was determined as the ratio (Vb/Va) of the volume Va per unit mass (e.g., 100 g) of the (meth)acrylic ester polymer emulsion after mechanical foaming and after being heated and dried to the volume Vb per unit mass (e.g., 100 g) of the (meth)acrylic ester polymer emulsion after mechanical foaming and after being heated and dried.

The basis weight of the foamed adsorption sound-absorbing layer was determined as follows for a laminate (corresponding to the first laminate 31 shown in Figure 3) having a foamed adsorption sound-absorbing layer on release PET prepared in the process of manufacturing the sound-absorbing sheet.

[Weight of release PET]
The release PET was cut into a size of 10 cm x 10 cm and left for 24 hours at a temperature of 23°C and a humidity of 50% RH without load, after which the mass W1 (g) was measured and the basis weight A (g/ ^m2 ) of the release PET was calculated by W1/0.01.
The "weight" of the release PET mentioned above refers to the weight per unit area of the release PET, and is usually expressed in grams per square ^meter .

[Weight of foamed sound absorbing layer]
The laminate having a foamed adsorption sound-absorbing layer on a release PET was cut to a size of 10 cm x 10 cm and left for 24 hours without load at a temperature of 23°C and a humidity of 50% RH.The mass W2 (g) was then measured and the basis weight B (total basis weight: g/ ^m2 ) of the laminate having a foamed adsorption sound-absorbing layer on a release PET was first calculated using W2/0.01.
The basis weight C (g/m ² ) of the foamed adsorbent sound absorbing layer was calculated by subtracting the basis weight A (g/m ² ) of the release PET measured above from the obtained basis weight B. That is, the basis weight C was calculated by C=B-A.

(Manufacturing of sound absorbing sheets)
As the sound absorbing sheet of Example 1, a sound absorbing sheet having the configuration shown in FIG. 8 was manufactured.
First, a foamed urethane sheet Rubilar L31 manufactured by Toyo Polymer Co., Ltd. was used as the base material for the sound-absorbing sheet, and a base material was produced having two layers, a first base material layer 121A and a second base material layer 121B, as in the sound-absorbing sheet 120 shown in Fig. 8, in which the first base material layer 121A has a cutout portion 125B in a part of the outer periphery, and this cutout portion 125B is connected to the opening 125A. Here, the thickness (T1) of the first base material layer 121A was 13 mm, and the thickness (T2) of the second base material layer 121B was 7 mm.
Next, an acrylic adhesive (50 μm thick) composed of a (meth)acrylic acid ester copolymer was formed as an adhesive layer on the first base material layer 121A of the two-layered base material thus produced, to produce a laminate corresponding to the second laminate 32 shown in Fig. 3. A highly adhesive adhesive sheet was used for this acrylic adhesive, and the lamination strength between the base material and the adhesive sheet, and between the foamed adsorption sound absorbing layer and the adhesive sheet was 10 N/25 mm or more.
Thereafter, the adhesive layer of this laminate (corresponding to the second laminate 32 shown in Figure 3) was bonded to the foamed adsorption sound-absorbing layer of the laminate (corresponding to the first laminate 31 shown in Figure 3) on which the above-mentioned foamed adsorption sound-absorbing layer had been formed, thereby producing the sound-absorbing sheet of Example 1.

Example 2
The sound-absorbing sheet of Example 2 was manufactured in the same manner as in Example 1, except that the spacer frame for setting the thickness of the foamed adsorption sound-absorbing layer was set to a thickness of 200 μm and the heating and drying time was set according to this thickness.
The formed foamed sound-absorbing layer had a thickness of 200 μm, an expansion ratio of 2.0, and a basis weight of 63 g/m ^2. The heat drying time was 40 minutes or less.

Example 3
The sound-absorbing sheet of Example 3 was manufactured in the same manner as in Example 1, except that the stirring rotation speed of the batch type foaming machine in the mechanical foaming step of manufacturing the foamed adsorption sound-absorbing layer was 250 rpm, the spacer frame for setting the thickness of the foamed adsorption sound-absorbing layer was 500 μm in thickness, and the heating and drying time was set according to this thickness.
The formed foamed sound-absorbing layer had a thickness of 500 μm, an expansion ratio of 4.0, and a basis weight of 80 g/m ^2. The heat drying time was 40 minutes or less.

Example 4
The sound-absorbing sheet of Example 4 was manufactured in the same manner as in Example 1, except that the stirring rotation speed of the batch type foaming machine in the mechanical foaming step of manufacturing the foamed adsorption sound-absorbing layer was 180 rpm, the spacer frame for setting the thickness of the foamed adsorption sound-absorbing layer was 5000 μm in thickness, and the heating and drying time was set according to this thickness.
The formed foamed sound-absorbing layer had a thickness of 5000 μm, an expansion ratio of 3.0, and a basis weight of 600 g/m ^2. The heat drying time was more than 40 minutes and not more than 60 minutes.

(Comparative Example 1)
The sound-absorbing sheet of Comparative Example 1 was manufactured in the same manner as in Example 1, except that the spacer frame for setting the thickness of the foamed adsorption sound-absorbing layer was set to a thickness of 100 μm and the heating and drying time was set according to this thickness.
The formed foamed sound-absorbing layer had a thickness of 100 μm, an expansion ratio of 2.0, and a basis weight of 52 g/m ^2. The heat drying time was 40 minutes or less.

(Comparative Example 2)
The sound-absorbing sheet of Comparative Example 2 was manufactured in the same manner as in Example 1, except that the stirring rotation speed of the batch type foaming machine in the mechanical foaming step of manufacturing the foamed adsorption sound-absorbing layer was set to 180 rpm, the spacer frame for setting the thickness of the foamed adsorption sound-absorbing layer was set to a thickness of 6000 μm, and the heating and drying time was set according to this thickness.
The formed foamed sound-absorbing layer had a thickness of 6000 μm, an expansion ratio of 3.0, and a basis weight of 700 g/m ^2. The heat drying time required exceeded 60 minutes.

(evaluation)
[Peel strength and peelability]
The peel strength and peelability of the foamed adsorption sound absorbing layer of each sound absorbing sheet was evaluated for Examples 1 to 4 and Comparative Examples 1 and 2. The results are shown in Table 1. Here, the adherend used was a LLDPE (Linear Low Density Polyethylene) sheet (100 μm thick) of the same grade as the material constituting the pouch of the stoma appliance. The peel strength of this foamed adsorption sound absorbing layer corresponds to the adhesive strength of the foamed adsorption sound absorbing layer.

The peel strength was measured under the following conditions by attaching each sound absorbing sheet to an LLDPE sheet at a width of 25 mm and peeling it off in a 180° direction (unit: N/25 mm). The peel strength shown in Table 1 was judged according to the following criteria.

(conditions)
Pressing method: 2 kg roller, 1 round trip Pressing temperature: 23°C/50% RH
Curing conditions: Room temperature (23℃/50%RH) x 30min
Tensile speed: 300 mm/min
Pull angle: 180°
Measurement temperature: room temperature (23℃/50%RH)

(Criteria for Peel Strength)
◎: Excellent peel strength ○: Good peel strength

The peelability shown in Table 1 was evaluated by visually inspecting the adherend surface and the foamed adsorbent sound absorbing layer after peeling the sound absorbing sheet from the adherend, according to the following criteria:

(Criteria for evaluating peelability)
◎: No film remains of the foamed sound-absorbing layer on the adherend, and the foamed sound-absorbing layer of the sound-absorbing sheet is in good condition. 〇: No film remains of the foamed sound-absorbing layer on the adherend, but wrinkles have occurred in the foamed sound-absorbing layer of the sound-absorbing sheet.

[Productivity]
The productivity of each of the sound-absorbing sheets of Examples 1 to 4 and Comparative Examples 1 and 2 was evaluated based on the length of the heat-drying time. The results are shown in Table 1. The heat-drying time is the time required until substantially no dispersion medium is observed in the foamed, adsorbent sound-absorbing layer. The productivity shown in Table 1 was judged according to the following criteria.

(Productivity criteria)
◎: Heat drying time is 40 minutes or less. ◯: Heat drying time is more than 40 minutes but less than 60 minutes. ×: Heat drying time is more than 60 minutes.

[Sound insulation]
The sound-absorbing properties of each of the sound-absorbing sheets of Examples 1 to 4 and Comparative Examples 1 and 2 were evaluated. The results are shown in Table 1.
The sound insulation was measured as follows: White noise was used as a sound source, and the sound pressure that reached the microphone through the base material alone or each sound-absorbing sheet was analyzed to obtain the RMS value (Root Mean Square value) at frequencies from 25 Hz to 10,000 Hz.
Here, the RMS value of the environmental sound in the frequency range of 25 Hz to 10,000 Hz was 58.6 (dB), and the RMS value of the white noise was 58.6 (dB).
The above-mentioned substrate alone refers to the form of only the substrate, excluding the adhesive layer (corresponding to adhesive layer 12 in sound-absorbing sheet 120 shown in Figure 8) and the foamed adsorption sound-absorbing layer (corresponding to foamed adsorption sound-absorbing layer 13 in sound-absorbing sheet 120 shown in Figure 8) from the sound-absorbing sheet of Example 1.

(Measurement conditions)
Distance from sound source to microphone: 50 mm
Microphone:
Free-field microphone 352B02 manufactured by PCB Corporation and sold by Toyo Corporation was used. Sound pressure analysis:
Analyze sound pressure at 25Hz frequency intervals using an OROS FFT analyzer sold by Toyo Corporation

Next, the sound absorption efficiency (%) of each sound absorbing sheet was calculated from each RMS value obtained. This sound absorption efficiency (%) was calculated from the following formula, where Ra is the RMS value of the substrate alone and Rx is the RMS value of each sound absorbing sheet.
Sound absorption efficiency (%) = 100 x (Ra - Rx) / Ra
The RMS values for the substrate alone and each sound absorbing sheet are shown in Table 2. The sound insulation properties shown in Table 1 were judged based on the sound absorption efficiency shown in Table 2 according to the following criteria.

(Sound insulation evaluation criteria)
◎: Sound absorption efficiency is 2.5% or more. ◯: Sound absorption efficiency is 1% or more and less than 2.5%. ×: Sound absorption efficiency is less than 1%.

As can be seen from Table 1, the sound absorbing sheets of Examples 1 to 4 all had good results in terms of peel strength, releasability, productivity, and sound insulation. In particular, the sound absorbing sheet of Example 3 all had excellent results in terms of peel strength, releasability, productivity, and sound insulation. Here, the sound absorbing sheets of Examples 1 to 4 had a thickness of the foamed adsorption sound absorbing layer that satisfied the range of 150 μm or more and 5000 μm or less. Furthermore, the sound absorbing sheets of Examples 1 to 4 had a basis weight of the foamed adsorption sound absorbing layer that satisfied the range of 60 g/ ^m2 or more and 600 g/m2 or ^less . Furthermore, the sound absorbing sheets of Examples 1 to 4 had an expansion ratio of the foamed adsorption sound absorbing layer that satisfied the range of 2.0 or more and 4.0 or less.

On the other hand, as can be seen from Table 1, the sound absorbing sheet of Comparative Example 1, in which the thickness of the foamed adsorption sound absorbing layer was thinner than each of the sound absorbing sheets of Examples 1 to 4, had inferior sound insulation properties to each of the sound absorbing sheets of Examples 1 to 4. Here, the thickness of the foamed adsorption sound absorbing layer of the sound absorbing sheet of Comparative Example 1 was 100 μm, and the basis weight of the foamed adsorption sound absorbing layer was 52 g/ ^m2 .

Furthermore, as can be seen from Table 1, the sound absorbing sheet of Comparative Example 2, in which the foamed adsorption sound absorbing layer was thicker than the sound absorbing sheets of Examples 1 to 4, was inferior in productivity to the sound absorbing sheets of Examples 1 to 4.
Here, the thickness of the foamed sound-absorbing layer of the sound-absorbing sheet of Comparative Example 2 was 6000 μm, and the basis weight of the foamed sound-absorbing layer was 700 g/m ² .

As described above, the sound absorbing sheets according to the present disclosure illustrated in Examples 1 to 4 all showed good results in terms of peel strength, releasability, productivity, and sound insulation. Therefore, the sound absorbing sheets according to the present disclosure illustrated in Examples 1 to 4 can be suitably used in stoma appliances as a removable sound absorbing mechanism.
Furthermore, in a stoma appliance using the sound-absorbing sheet according to the present disclosure, the sound-absorbing sheet can be easily attached and detached, and when the sound-absorbing sheet is worn, the sound emitted from the stoma can be effectively reduced.

Although the respective embodiments of the sound-absorbing sheet and stoma appliance according to the present disclosure have been described above, the present disclosure is not limited to the above-mentioned embodiments. The above-mentioned embodiments are merely examples, and anything that has substantially the same configuration as the technical idea of the present disclosure and exhibits similar effects is included within the technical scope of the present disclosure in any case.

Reference Signs List 1, 2 Sound absorbing sheet 11 Base material 12 Adhesive layer 13 Foamed adsorbent sound absorbing layer 21 Release material 31, 31A, 31B First laminate 32 Second laminate 41 First release material 42 Second release material 101 Stoma appliance 111 Base plate 112 Stoma hole 113 Pouch 114 Outlet 120 Sound absorbing sheet 121A First base material layer 121B Second base material layer 125A Opening 125B Cutout portion 200 Stoma appliance 211 Base plate 212 Stoma hole 213 Pouch 214 Outlet

Claims (8)

It has a laminated structure in which an adhesive layer and a foamed sound-absorbing layer are laminated in this order on a base material,
the foamed sound-absorbing layer is made of a foamed (meth)acrylic acid ester polymer,
The thickness of the foamed sound-absorbing layer is 150 μm or more and 5000 μm or less ,
The substrate has a laminated structure in which a first substrate layer and a second substrate layer are laminated,
the first base layer has an opening;
The first base layer has a notch in a part of an outer periphery thereof,
The cutout portion is connected to the opening,
A sound-absorbing sheet , comprising the foamed adsorbent sound-absorbing layer provided on a side of the first base material layer opposite to the side on which the second base material layer is located . The sound absorbing sheet according to claim 1 , wherein the foamed sound absorbing layer has a basis weight of 60 g/m ² or more and 600 g/m ² or less. The sound absorbing sheet according to claim 1 or 2, wherein the foaming ratio of the foamed adsorption sound absorbing layer is 2.0 or more and 4.0 or less. The sound-absorbing sheet according to any one of claims 1 to 3, wherein the adhesive layer is composed of a (meth)acrylic acid ester copolymer. The sound absorbing sheet according to any one of claims 1 to 4, wherein the substrate comprises polyurethane foam. The sound absorbing sheet according to claim 1 , wherein the first base material layer has a thickness greater than a thickness of the second base material layer. A base plate that is attached to the skin around the stoma and has a stoma hole through which the stoma is inserted;
a pouch connected to the base plate for receiving waste from the stoma;
A sound absorbing sheet attached onto the surface of the pouch;
Equipped with
The sound absorbing sheet is
It has a laminated structure in which an adhesive layer and a foamed sound-absorbing layer are laminated in this order on a base material,
the foamed sound-absorbing layer is made of a foamed (meth)acrylic acid ester polymer,
The thickness of the foamed sound-absorbing layer is 150 μm or more and 5000 μm or less ,
A stoma appliance in which the sound-absorbing sheet is removably attached onto the surface of the pouch on the side of the foam-adsorbent sound-absorbing layer. The stoma appliance according to claim 7 , wherein the sound-absorbing sheet is attached in a position covering the stoma hole when viewed from a direction perpendicular to the base plate.