JP7822362B2 - Waterproof sound-transmitting materials - Google Patents

Description

The present invention relates to a waterproof sound-permeable component that is less likely to experience increased acoustic loss due to compression when installed in a housing.

Electrical and electronic products such as mobile phones, smartphones, smartwatches, cordless phones, portable media players, portable game consoles, digital cameras, digital video cameras, and earphones (hereinafter referred to simply as "electrical products," but the concept is used to include electronic products as well) have sound-receiving and sound-producing units such as microphones and speakers in their housing structures, with openings provided in the corresponding positions, and sound is transmitted through these openings.

As exemplified by the widespread use of smartphones, these electrical appliances are increasingly being used outdoors or in wet environments at home, making it desirable for them to have a waterproof structure. For example, smartphones with waterproof features are becoming more common.

Conventionally, waterproof sound-transmitting members that prevent water from entering the housing and have low acoustic loss are attached to the openings in the sound-producing and sound-receiving sections. Waterproof sound-transmitting members consist of a waterproof sound-transmitting membrane and a support layer laminated around its periphery, and have a sound-transmitting area where the waterproof sound-transmitting membrane is exposed.

The support layer maintains the shape of the component and bonds it to the housing, allowing sound to pass through the waterproof sound-permeable membrane in the sound-permeable area. Waterproof sound-permeable components are sometimes incorporated into electrical products in a compressed state to prevent water intrusion and sound leakage from the interface with the housing.

The acoustic loss of waterproof sound-permeable components can be reduced by using soft materials for the waterproof sound-permeable membrane and by reducing the basis weight. Selecting a material with a low specific gravity and using a porous structure are effective ways to reduce the basis weight. However, waterproof sound-permeable membranes made of soft materials and with a porous structure are prone to deformation when compressed.

Patent Document 1 discloses a waterproof sound-transmitting membrane that reduces acoustic loss by using a soft material such as polyurethane. Patent Document 2 discloses a waterproof sound-transmitting component that uses a soft material such as silicone rubber in the waterproof sound-transmitting membrane so that acoustic loss does not increase when water pressure is returned to normal pressure after being applied. Patent Document 3 discloses a waterproof sound-transmitting component that reduces distortion of transmitted sound by using a polyolefin resin foam in the support layer within the waterproof sound-transmitting component.

WO2015/105052 JP 2014-7738 A JP 2015-142282 A

Waterproof sound-transmitting membranes, which are made of soft material and have a porous structure, have low acoustic loss, but are easily deformed by external forces. If such a waterproof sound-transmitting membrane is used as a waterproof sound-transmitting component, distortion occurs when it is compressed and incorporated into a housing, increasing acoustic loss.

The waterproof sound-permeable component disclosed in Patent Document 1, which uses a waterproof sound-permeable membrane made of a soft material, is not suitable for incorporation into a housing with a high compression ratio.

Patent Document 2 discloses a waterproof sound-transmitting member that uses a waterproof sound-transmitting membrane made of a soft material. After the waterproof sound-transmitting membrane is distorted by water pressure, the distortion is resolved when normal pressure is restored, and acoustic loss returns to normal. However, no consideration is given to acoustic loss in a configuration in which the waterproof sound-transmitting member is compressed and incorporated, and pressure is constantly applied to the waterproof sound-transmitting membrane.

Patent Document 3 discloses a waterproof sound-transmitting component that uses a foam for the support layer, reducing sound distortion caused by interference in the support layer. While attention is focused on the dynamic viscoelasticity of the support layer, such as the loss modulus and loss elastic coefficient, flexibility is not taken into consideration. Also, no consideration is given to distortion of the waterproof sound-transmitting membrane when the waterproof sound-transmitting component is compressed and assembled.

The present invention aims to provide a waterproof sound-transmitting component that can be used with a high compression ratio. In particular, the objective is to provide a waterproof sound-transmitting component that can be compressed and incorporated into a housing even when using a waterproof sound-transmitting membrane made of a soft material with low acoustic loss, thereby making it possible to keep overall acoustic loss low.

After extensive research, the inventors discovered that by devising a combination of the waterproof sound-permeable membrane and the support layer so that the stress required to compress the waterproof sound-permeable component by 40% in a direction perpendicular to the membrane surface is between 1 and 600 kPa, it is possible to reduce acoustic loss when used at high compression rates, leading to the completion of this invention.

That is, the present invention relates to the following waterproof sound-transmitting member.
(1) A waterproof sound-transmitting member in which a support layer is laminated on at least one side of a waterproof sound-transmitting membrane, the waterproof sound-transmitting membrane has exposed sound-transmitting areas on both sides, the stress required to compress the waterproof sound-transmitting membrane by 40% in a direction perpendicular to the membrane surface is 1 to 600 kPa, and the waterproof sound-transmitting membrane is a porous membrane .

(2) The waterproof sound-transmitting member according to (1) , wherein the support layer is composed of a single layer or multiple layers, and includes a layer using a sheet having a stress of 600 kPa or less required for 40% compression in at least the vertical direction.

(3) The waterproof sound-transmitting member according to (2) , wherein the sheet having a stress of 600 kPa or less required for 40% compression in the vertical direction includes a sheet layer made of a synthetic resin porous material.
(4) The waterproof sound-transmitting member according to (3) , characterized in that the synthetic resin porous material is a synthetic resin porous material selected from the group consisting of polyolefin resins, polyurethane resins, and acrylic resins.

(5) Among the layers constituting the support layer, a layer using a sheet having a stress of 600 kPa or less required for 40% compression in the vertical direction accounts for 40% or more of the overall thickness of the waterproof sound-transmitting member. (2) A waterproof sound-transmitting member according to any one of (4) to (4) .
(6) The waterproof sound-transmitting member according to (1) , characterized in that the waterproof sound-transmitting membrane has a tensile modulus of elasticity of 0.5 to 20 MPa.

(7) The waterproof sound-transmitting member according to (1) , characterized in that the waterproof sound-transmitting membrane contains a material having a 100% modulus of 1 to 20 MPa.
(8) The waterproof sound-transmitting member according to (1), wherein the waterproof sound-transmitting membrane has an air permeability of 3 to 500 seconds/100 mL according to the JIS L 1096 Gurley method.

(9) The waterproof sound-transmitting member according to (1), wherein the waterproof sound-transmitting membrane has a thickness of 15 to 80 μm.
(10) The waterproof sound-transmitting member according to (1), characterized in that the waterproof sound-transmitting membrane is made of polyurethane resin.
(11) The waterproof sound-transmitting member according to (1) , characterized in that the area of the support layer laminated on at least one side of the waterproof sound-transmitting membrane is 1 to 50 mm ² .

(12) The waterproof sound-transmitting member according to (1), wherein the sound-transmitting region satisfies at least one of the following conditions a) and b).
a) The planar shape has no corners and a circularity of 0.45 to 1
b) The area is 0.5 to 40 ^mm2
(13) The waterproof sound-transmitting member according to (1), wherein the support layer satisfies at least one of the following conditions c) and d).
c) It must be laminated on both sides of the waterproof sound-permeable membrane.
d) It is laminated around the periphery of the waterproof sound-permeable membrane.

A waterproof sound-transmitting component, which has a waterproof sound-transmitting membrane and a support layer, is compressed in its thickness direction (perpendicular to the surface of the waterproof sound-transmitting membrane) when it is installed in a housing. The force exerted by the compression is applied to the waterproof sound-transmitting membrane through the support layer. If excessive force is applied to the waterproof sound-transmitting membrane, distortion occurs, inhibiting vibrations caused by the incident sound and increasing acoustic loss.

According to the present invention, by setting the stress required to compress the waterproof sound-transmitting member by 40% in the direction perpendicular to the membrane surface to 600 kPa or less, it is possible to reduce the force applied to the waterproof sound-transmitting membrane when the waterproof sound-transmitting member is incorporated into a housing at a high compression rate, thereby minimizing acoustic loss. This technical effect can be more reliably achieved by optimally combining the support layer material, membrane material, component shape, etc.

In other words, by using a waterproof sound-permeable membrane that is easily deformed and has a relatively low tensile modulus, and combining it with a support layer made of a material that has a certain thickness and low compressive stress, it is possible to prevent an increase in acoustic loss due to compression when the membrane is installed in a housing.

1 is a cross-sectional view of an example of the configuration of a waterproof sound-transmitting member of the present invention. 1 is a plan view of an example of the configuration of a waterproof sound-transmitting member of the present invention. FIG. 1 is a schematic diagram of an acoustic measurement device. FIG. 1 is a schematic diagram of a compression test.

The waterproof sound-transmitting member of the present invention is a waterproof sound-transmitting member in which a support layer is laminated on at least one side of a waterproof sound-transmitting membrane, and is characterized in that there are sound-transmitting areas where the waterproof sound-transmitting membrane is exposed on both sides, and the stress required to compress the waterproof sound-transmitting member by 40% in a direction perpendicular to the membrane surface is 1 to 600 kPa.

Figure 1 shows an example of the configuration of a waterproof sound-transmitting member of the present invention. As shown in Figure 1, the waterproof sound-transmitting member 1 of the present invention has support layers 3 laminated on both sides of a waterproof sound-transmitting membrane 2 so that they are positioned around the periphery of the sound-transmitting area 4.

1. Waterproof sound-transmitting member (1) Configuration The waterproof sound-transmitting member of the present invention includes a waterproof sound-transmitting membrane and a support layer, and the support layer is laminated on at least a portion of at least one surface of the waterproof sound-transmitting membrane. Furthermore, there are areas (= sound-transmitting areas) where the support layer is not laminated and the waterproof sound-transmitting membrane is exposed on both sides.

In the waterproof sound-transmitting component of the present invention, sound transmits through this sound-transmitting area. The incident sound vibrates the waterproof sound-transmitting membrane and is transmitted through to the opposite side. That is, in the waterproof sound-transmitting component of the present invention, a support layer is laminated on the area of the waterproof sound-transmitting membrane other than the sound-transmitting area.

(2) Compressive stress The waterproof sound-transmitting member is compressed in a direction perpendicular to the surface of the waterproof sound-transmitting membrane (thickness direction of the member) when it is installed in the housing. The force exerted by the compression is applied to the waterproof sound-transmitting membrane through the support layer. If excessive force is applied to the waterproof sound-transmitting membrane, distortion occurs, inhibiting vibrations caused by the incident sound and increasing acoustic loss.

In order to reduce the force acting on the waterproof sound-permeable membrane and reduce acoustic loss when the waterproof sound-permeable member is incorporated into a housing at a high compression rate, the stress required to compress the waterproof sound-permeable member by 40% in a direction perpendicular to the membrane surface of the waterproof sound-permeable membrane must be 600 kPa or less, preferably 400 kPa or less, and even more preferably 300 kPa or less.

On the other hand, by pressing and fixing the waterproof sound-transmitting member against the housing, the dissipation of energy due to the vibration of the waterproof sound-transmitting membrane is suppressed and acoustic loss is reduced, so the stress required to compress the waterproof sound-transmitting member by 40% in the direction perpendicular to the membrane surface of the waterproof sound-transmitting membrane must be 1 kPa or more, preferably 20 kPa or more, and even more preferably 40 kPa or more.

The method for measuring compressive stress in this invention is outlined in Figure 4. In Figure 4, 1 is the waterproof sound-transmitting member, 17 is the parallel plate, and 18 is the compression direction.

Compression tests generally involve sandwiching a test specimen between two parallel plates in a compression testing machine and applying a load to determine the stress. In this invention, the test specimen (waterproof sound-transmitting member) is sandwiched between parallel plates so that the parallel plate surfaces are parallel to the membrane surface of the waterproof sound-transmitting membrane. In this case, if the support layer of the waterproof sound-transmitting member is provided on both sides of the waterproof sound-transmitting membrane, the support layers on both sides are placed so that they contact the parallel plates. On the other hand, if the support layer of the waterproof sound-transmitting member is provided on only one side of the waterproof sound-transmitting membrane, the waterproof sound-transmitting membrane and the support layer are each placed so that they contact the parallel plates.

Then, the parallel plates are moved perpendicular to the membrane surface of the waterproof sound-permeable membrane to narrow the gap between the two parallel plates so that a compressive force is applied perpendicular to the membrane surface of the waterproof sound-permeable membrane, thereby applying a compressive force to the waterproof sound-permeable member.

The "stress required for 40% compression" in the present invention can be calculated by taking the thickness of the waterproof sound-transmitting component (the sum of the thicknesses of the support layer and the waterproof sound-transmitting membrane) as 100%, measuring the stress when that thickness is compressed by 40% (when the thickness after compression is compressed to 60% of the thickness before compression), and dividing this by the area of the support layer.

The area of the support layer refers to the area of the part of the support layer that comes into contact with the parallel plates of the compression tester when the support layer is a single layer or when multiple support layers are stacked and their shape is uniform. However, when multiple support layers are stacked and their shape is not uniform, the area to which force is applied when compressed is calculated as the area of the part where the multiple support layers overlap most in the vertical direction (the direction perpendicular to the membrane surface of the waterproof sound-permeable membrane or the compression direction).

For example, if the area of the outermost support layer (the layer in contact with the parallel plate) is large and a smaller area is stacked on the inner layer, the stress will be applied to the area of the inner layer that overlaps vertically, and the area of the support layer will be the area of the inner layer. On the other hand, if the area of the outermost support layer is small and a larger area is stacked on the inner layer, the stress will be applied to the area of the outermost layer, and the area of the support layer will be the area of the outermost layer.

2. Waterproof sound-transmitting membrane (1) Physical properties of the membrane The waterproof sound-transmitting membrane used in the waterproof sound-transmitting member of the present invention is a membrane that allows sound to pass through and blocks water from passing through, and has a sound-permeable region in at least a portion. The more flexible the waterproof sound-transmitting membrane, the easier it is to vibrate and the smaller the acoustic loss. The tensile modulus of elasticity of the waterproof sound-transmitting membrane, which is an index of its softness, is preferably 20 MPa or less, and more preferably 10 MPa or less.

On the other hand, in order to reduce distortion due to compression of the waterproof sound-permeable member and reduce acoustic loss, it is preferable that the tensile modulus of the waterproof sound-permeable membrane be 0.5 MPa or more, and more preferably 2 MPa or more.

Using a soft material is effective in reducing the tensile modulus of a waterproof sound-transmitting membrane. It is preferable that the 100% modulus, which is an index of the softness of a material, be 1 to 20 MPa. The 100% modulus of a material is a physical property of the material itself that makes up the waterproof sound-transmitting membrane, and is not affected by factors such as the porous structure. The 100% modulus of the present invention is a value measured on a non-porous membrane obtained by dissolving the waterproof sound-transmitting membrane in a solvent and then drying it.

Furthermore, the waterproof sound-permeable membrane of the present invention preferably has a water pressure resistance according to JIS L 1092 Method B (high water pressure method) of 10 to 400 kPa, and more preferably 30 to 400 kPa. A water pressure resistance in the range of 10 to 400 kPa provides high sound permeability and waterproofing.

The breaking elongation of the waterproof sound-permeable membrane is preferably 100 to 500%, more preferably 150 to 400%, and especially preferably 80 to 260%. A breaking elongation of 100 to 500% ensures good sound permeability and sufficient waterproofing.

The waterproof sound-permeable membrane preferably has an air permeability of 3 to 500 seconds/100 mL according to the JIS L 1096 Gurley method, and more preferably 3 to 300 seconds/100 mL. An air permeability of 3 to 500 seconds/100 mL ensures good sound permeability.

In addition, the waterproof sound-permeable membrane of the present invention has sound permeability such that the acoustic loss at a frequency of 1 kHz is less than 10 dB, the acoustic loss at a frequency of 2 kHz is less than 5 dB, and the acoustic loss at a frequency of 5 kHz is less than 5 dB.

(2) Membrane Material The material constituting the waterproof sound-permeable membrane used in the present invention is not particularly limited, but as mentioned above, a relatively soft material is preferred, and more preferably, a soft synthetic resin that satisfies the above-mentioned 100% modulus range (1 to 20 MPa) is used.

Specifically, it is preferable to use elastomers such as polyurethane resin and silicone rubber. Furthermore, waterproof sound-permeable membranes are porous because they become softer when made porous . It is more preferable to use a polyurethane resin porous membrane because the structure is easy to control.

Polyurethane resins include polyester-based polyurethanes, polyether-based polyurethanes, polycarbonate-based polyurethanes, etc. It is preferable to use at least one of these, and two or more may be mixed together.

Here, polyurethane resin is a resin obtained by polymerizing an isocyanate component and a polyol component.

Examples of isocyanate components include aliphatic diisocyanates, aromatic diisocyanates, and alicyclic diisocyanates, which may be used alone or in combination of two or more. Specific examples of aliphatic diisocyanates include 1,6-hexamethylene diisocyanate. Examples of aromatic diisocyanates include xylylene diisocyanate, 4,4'-diphenylmethane diisocyanate, and tolylene diisocyanate. Examples of alicyclic diisocyanates include 1,4-cyclohexane diisocyanate, dicyclohexylmethane diisocyanate, and isophorone diisocyanate. Furthermore, trifunctional or higher isocyanates may also be used if necessary.

On the other hand, examples of polyol components include polyester polyols made using polyethylene adipate, polybutylene adipate, polycaprolactone polyol, etc.; polycarbonate polyols made using polyhexamethylene carbonate, etc.; and polyether polyols made using polyethylene glycol, polypropylene glycol, polytetramethylene glycol, etc. These can be used alone or in combination of two or more.

Various additives may also be added to the polyurethane resin as needed. Examples of additives include water repellents, crosslinking agents, inorganic fine particles, plasticizers, antioxidants, UV absorbers, smoothing agents such as amide wax, hydrolysis inhibitors, pigments, anti-yellowing agents, and matting agents.

Preferably, the synthetic resin porous film is a porous film formed by solidifying in water a synthetic resin solution containing a synthetic resin and a water-soluble polar organic solvent. Using the aforementioned polyurethane resin as an example, one method for producing such a porous film is to apply a polyurethane resin solution containing a polyurethane resin, inorganic fine particles, and a polar organic solvent to one side of a suitable release substrate, and then immerse the applied polyurethane resin solution in water to solidify the polyurethane resin.

The polyurethane resin solution can contain inorganic fine particles with hydrophobic surfaces. Because inorganic fine particles with hydrophobic surfaces have a high affinity for polar organic solvents, the inorganic fine particles with hydrophobic surfaces are surrounded by the polar organic solvent in the solution, resulting in a locally high concentration of the polar organic solvent. Therefore, during the process of immersing the polyurethane resin solution in water to solidify the polyurethane resin, pores are formed around the inorganic fine particles with hydrophobic surfaces. This makes it possible to efficiently form a porous membrane made of polyurethane resin.

Examples of inorganic fine particles include fine particles of carbonates such as calcium carbonate and magnesium carbonate; silicic acids such as silicon dioxide and diatomaceous earth; silicates such as talc and zeolite; hydroxides such as aluminum hydroxide and magnesium hydroxide; sulfates such as barium sulfate and calcium sulfate; borates such as aluminum borate and zinc borate; titanates such as potassium titanate; metal oxides such as zinc oxide and titanium oxide; and carbonaceous materials such as carbon black.

These inorganic microparticles may be either porous or non-porous. Furthermore, the shape of the inorganic microparticles is not particularly limited, and may be regular, such as polygonal, needle-like, spherical, cubic, spindle-like, or plate-like, or irregular. The above inorganic microparticles may be used alone or in combination of two or more. Among these, calcium carbonate microparticles or silicon dioxide microparticles are preferred because they have a high adsorption capacity for polar organic solvents such as N,N-dimethylformamide and are easy to form micropores.

The content of the inorganic microparticles varies depending on the type and cannot be generalized, but it is generally preferable that it be 1 to 75% by mass based on the total solids content of the polyurethane resin solution. A content of 1% by mass or more will result in sufficient porosity. A content of 75% by mass or less will maintain the strength, particularly tensile strength, of the resulting microporous film and provide sufficient waterproofing. The content of the inorganic microparticles is preferably 3 to 40% by mass based on the total solids content of the polyurethane resin solution.

Examples of polar organic solvents include N,N-dimethylformamide and N,N-dimethylacetamide.

A waterproof sound-permeable membrane according to a preferred embodiment can be manufactured, for example, by applying a polyurethane resin solution containing a synthetic resin primarily composed of polyurethane resin, inorganic fine particles in an amount of 1 to 75% by mass relative to the total solids content, and a polar organic solvent to a releasable substrate.

Methods for applying a polyurethane resin solution to a releasable substrate include, for example, using a floating knife coater, roll-on knife coater, comma coater, reverse coater, lip coater, roll coater, or die coater.

The amount of polyurethane resin solution applied is preferably 10 to 200 g/ ^m2 , more preferably 10 to 750 g/ ^m2 , in terms of solid content. By setting the application amount within this range, a porous membrane having a thickness of 10 to 150 μm can be obtained. In other words, the waterproof sound-permeable membrane of the present invention preferably has a thickness of 10 to 150 μm, more preferably 15 to 80 μm.

Following the process of applying the polyurethane resin solution to the releasable substrate, the polyurethane resin solution is immersed in water at 10-40°C. During this process, water penetrates into the polyurethane resin solution, and the polar organic solvent contained in the polyurethane resin solution is almost completely replaced by water, causing the polyurethane resin to solidify.

The immersion time in water is preferably between 30 seconds and 10 minutes, and more preferably between 1 and 5 minutes. If the immersion time is less than 30 seconds, the polyurethane resin may not solidify completely, resulting in insufficient pores being formed and insufficient waterproofing or sound permeability being achieved. If the immersion time exceeds 10 minutes, productivity will decrease.

Then, it is washed in warm water at 30-80°C for 3-15 minutes to remove any remaining polar organic solvent, and then heat-treated at 50-150°C for 1-10 minutes to dry. The release substrate is then removed, and a porous film made of polyurethane resin is formed.

The manufacturing method for the porous polyurethane resin membrane described above can also be applied to synthetic resins other than polyurethane resin. In the present invention, polyurethane resin is suitable due to its flexibility and ease of forming a porous structure, but porous membranes can also be manufactured and used using similar methods with other synthetic resins.

The porous membrane thus obtained may be subjected to a water-repellent treatment as a post-treatment, which can further improve waterproofing. Examples of water-repellent agents used in water-repellent treatment include paraffin-based water-repellents, silicone-based water-repellents, and fluorine-based water-repellents. Of these, fluorine-based water-repellents are preferred because they can impart high water repellency. Water-repellent treatment can be performed using standard methods such as padding or spraying.

The waterproof sound-permeable membrane used in the present invention may be a synthetic resin porous membrane such as the polyurethane resin porous membrane described above, or a rubber-like elastic material (thermosetting elastomer (rubber-based)). The rubber-like elastic material is not particularly limited as long as it is a material with rubber-like elasticity, but examples include silicone rubber, ethylene propylene diene rubber (EPDM), acrylic rubber, and natural rubber. Of these, silicone rubber, which has excellent properties such as heat resistance and chemical resistance, is particularly desirable.

(3) Membrane Thickness The waterproof sound-transmitting membrane used in the present invention preferably has a thickness of 10 to 150 μm, more preferably 15 to 80 μm. If the membrane is too thick, the sound permeability will be reduced and it will not be possible to use it in small electrical appliances with significant restrictions on built-in space. If the membrane is too thin, the strength will be reduced and it may become more susceptible to breakage.

2. Support layer (1) Structure of the support layer In addition to the waterproof function, the support layer has the function of supporting and fixing the waterproof sound-transmitting member to the housing and improving the handleability of the waterproof sound-transmitting member. Furthermore, the support layer can absorb the compressive pressure when the waterproof sound-transmitting member is installed in the housing, and can reinforce the membrane and stabilize its shape.

The support layer is laminated on at least one side of the waterproof sound-permeable membrane, and may be laminated on only one side or on both sides. Furthermore, the support layer is laminated on only part of the waterproof sound-permeable membrane surface, rather than the entire membrane surface.

Preferably, the support layer is laminated on both sides of the waterproof sound-transmitting membrane. If the support layer is laminated on both sides of the waterproof sound-transmitting membrane, the waterproof sound-transmitting membrane can be prevented from coming into direct contact with the housing when the waterproof sound-transmitting member is installed in the housing, making it less likely to suffer defects due to scratches or deformation.

To reduce the stress required to compress the waterproof sound-transmitting material by 40% in the direction perpendicular to the membrane surface to 1 to 600 kPa, it is effective to use a soft material for at least part of the support layer.

The layers constituting the support layer may be a single layer or multiple layers may be laminated, but it is preferable that at least some of the layers constituting the support layer (or the entire layer) include a layer made of a sheet for which the stress required to compress the layer by 40% in the vertical direction is 600 kPa or less, and it is even more preferable that the layer include a layer made of a sheet for which the stress required to compress the layer by 40% in the vertical direction is 300 kPa or less.

By including a layer using such a sheet with low compressive stress as the support layer and combining it with a waterproof sound-permeable membrane that has a relatively low tensile modulus and is easily deformed, it is possible to significantly reduce the increase in sound loss due to compression when the membrane is installed in equipment. Note that the "vertical direction" of the layers that make up the support layer refers to the thickness direction of the layer in question, or the direction perpendicular to the membrane surface of the waterproof sound-permeable membrane when laminated with the waterproof sound-permeable membrane.

If the support layer is a single layer, it is preferable that the layer be a layer using a sheet that requires a stress of 600 kPa or less to compress it 40% in the vertical direction, and more preferably a layer using a sheet that requires a stress of 300 kPa or less to compress it 40% in the vertical direction.

When the support layer consists of multiple layers, it is preferable that at least one of the layers constituting the support layer is a layer using a sheet that requires a stress of 600 kPa or less to compress it 40% in the vertical direction, and more preferably a layer using a sheet that requires a stress of 300 kPa or less to compress it 40% in the vertical direction.

When the support layer consists of multiple layers, there are no particular restrictions on the layer configuration, but multiple layers using sheets with a stress of 600 kPa or less required to compress by 40% in the vertical direction (hereinafter referred to as "sheets with a compressive stress of 600 kPa or less") may be laminated, including layers using different resin types or sheets with different compressive stresses within the above range.

In addition, a layer made of a hard sheet (a layer that hardly deforms when compressed during use) requiring a stress of more than 600 kPa to compress it by 40% in the vertical direction can be provided as a spacer layer.

(2) Layer Using Sheet with Compressive Stress of 600 kPa or Less The sheet with compressive stress of 600 kPa or less is preferably made of a synthetic resin material. Examples of synthetic resins include polyolefin resins, polyurethane resins, polyacrylic resins, and polyester resins.

Examples of polyolefin-based resins include polyethylene, polypropylene, and polyvinyl acetate. Examples of polyurethane-based resins include polyester-based polyurethane, polyether-based polyurethane, and polycarbonate-based polyurethane.

Examples of polyacrylic resins include polyacrylic esters and polymethacrylic esters. Examples of polyester resins include polyethylene terephthalate (PET) and polybutylene terephthalate.

Other examples include polyvinyl chloride, acrylic rubber, and silicone rubber. Preferably, a synthetic resin selected from the group consisting of polyolefin resins, polyacrylic resins, and polyurethane resins is used.

The synthetic resin material may be porous or non-porous, but to ensure that the stress required for 40% vertical compression is 600 kPa or less, it is preferable to use a sheet primarily made of a porous synthetic resin material (the layers that make up the sheet). Examples of porous synthetic resin materials include polyolefin-based porous materials such as polyethylene and polypropylene, polyurethane-based porous materials, and acrylic resin-based porous materials.

The sheet primarily made of a sheet layer made of the aforementioned porous synthetic resin material may consist solely of a sheet layer made of a porous synthetic resin material, or may be primarily made of a porous synthetic resin material and include other sheet layers. Examples of sheet layers made of materials other than porous synthetic resin materials include sheet layers (auxiliary layers) made of non-porous synthetic resin materials such as non-porous polyester resin materials.

There are no particular restrictions on the thickness of the auxiliary layer, but it is preferable that the stress required to compress the entire sheet by 40% in the vertical direction be 600 kPa or less. Therefore, the thickness of the sheet layer made of synthetic resin porous material relative to the thickness of the entire sheet is preferably 50% or more, more preferably 70% or more, and particularly preferably 80% or more.

A sheet with a compressive stress of 600 kPa or less may have an adhesive layer on at least one side. The adhesive layer may be provided on only one side or both sides of the sheet. The adhesive layer can be formed, for example, by applying an adhesive. Examples of adhesives include acrylic adhesives, silicone adhesives, and rubber adhesives.

There are no particular restrictions on the thickness of the adhesive layer, but it is preferable that the stress required to compress the entire sheet by 40% in the vertical direction be 600 kPa or less. Therefore, the thickness of the sheet layer made of synthetic resin porous material relative to the thickness of the entire sheet is preferably 50% or more, more preferably 70% or more, and particularly preferably 80% or more.

Even when both the auxiliary layer and adhesive layer are provided, it is preferable that the stress required to compress the entire sheet by 40% in the vertical direction be 600 kPa or less, and the thickness of the sheet layer made of synthetic resin porous material relative to the thickness of the entire sheet is preferably 50% or more, more preferably 70% or more, and particularly preferably 80% or more.

A preferred example of a layer (waterproof adhesive layer) using a sheet with a compressive stress of 600 kPa or less and provided with an adhesive layer is an adhesive waterproof tape made by applying an adhesive to one or both sides of a core material made of a porous synthetic resin material. Preferably, a double-sided adhesive waterproof tape is used, made by applying an adhesive to both sides of a core material made of a porous synthetic resin material. Such a waterproof adhesive layer provides waterproofing and adhesive functions at the interface between the waterproof sound-permeable membrane and the support layer, the interface between layers using each sheet within the support layer, and the interface between the support layer and the housing.

A sheet with a compressive stress of 600 kPa or less may not be provided with an adhesive layer. A layer (cushion layer) using a sheet with a compressive stress of 600 kPa or less that does not have an adhesive layer can be used to compress the cushion layer and fix it to the housing using the resulting repulsive force, thereby improving the waterproofness of the boundary between the housing and the waterproof sound-transmitting member. The cushion layer can also be the outermost layer of the support layer.

The thickness of a sheet with a compressive stress of 600 kPa or less is not particularly limited, but is preferably 10 μm or more, more preferably 30 μm or more, even more preferably 100 μm or more, and particularly preferably 150 μm or more. There is also no particular upper limit to the thickness, but it is preferably 3000 μm or less, more preferably 1500 μm or less, even more preferably 600 μm or less, and particularly preferably 400 μm or less.

The physical properties of a sheet with a compressive stress of 600 kPa or less are generally independent of the type of resin, but if the sheet with a compressive stress of 600 kPa or less is primarily composed of a sheet layer made of a polyolefin-based resin porous material, the stress required to compress it by 40% in the vertical direction is more preferably 50 to 300 kPa, and even more preferably 80 to 250 kPa.

When a sheet with a compressive stress of 600 kPa or less is primarily composed of a sheet layer made of a polyurethane-based resin porous material or a polyacrylic resin porous material, the stress required to compress it by 40% in the vertical direction is more preferably 0.1 to 100 kPa, even more preferably 0.1 to 30 kPa, and especially preferably 0.1 to 10 kPa. When constructing the support layer, it is preferable to combine layers of various resin types as needed.

Specific examples of sheets with a compressive stress of 600 kPa or less include sheets that have a sheet layer made primarily of a porous polyolefin resin material with adhesive layers on both sides. Alternatively, examples include sheets that have a sheet layer made primarily of a porous polyurethane resin material or a porous polyacrylic resin material with a non-porous PET layer as an auxiliary layer.

(3) Spacer Layer A layer using a hard sheet exhibiting high compressive stress can be provided as a spacer layer in a part of the support layer. The spacer layer is preferably formed from a non-porous synthetic resin, and specifically, a polyester film such as non-porous polyethylene terephthalate (PET) can be mentioned.

The spacer layer is expected to adjust the total thickness of the waterproof sound-transmitting member and stabilize the structure by supporting it (maintaining its thickness without deformation when the waterproof sound-transmitting member is compressed during use). The spacer layer may or may not have an adhesive layer. For example, it can be an adhesive waterproof tape with an adhesive applied to one or both sides, or a PET film with no adhesive applied.

The spacer layer is a hard layer that hardly deforms when compressed during use, and compressing it to a thickness of 40% is not easy in itself. It is certain that the stress required to compress it by 40% in the vertical direction is in the range of more than 600 kPa, but this is not necessarily clear. However, it is preferable that the compressive stress is at least 1 MPa or more, more preferably 10 MPa or more, and particularly preferably 100 MPa or more.

The thickness of a single spacer layer is not particularly limited, but is preferably 5 to 200 μm, more preferably 5 to 150 μm. When multiple spacer layers are included in the support layer, the total thickness is preferably 10 to 300 μm, more preferably 20 to 250 μm.

(4) Structure of the support layer (i) Layer configuration The support layer is laminated on at least one surface of the waterproof sound-transmitting membrane, and has the function of fixing the waterproof sound-transmitting member to the housing and improving handling. The support layer may be laminated on only one surface or both surfaces of the waterproof sound-transmitting membrane.

Preferably, the support layer is laminated on both sides of the waterproof sound-transmitting membrane. If the support layer is laminated on both sides of the waterproof sound-transmitting membrane, the waterproof sound-transmitting membrane can be prevented from coming into direct contact with the housing when the waterproof sound-transmitting member is installed in the housing, making it less likely to suffer defects due to scratches or deformation.

When the waterproof sound-permeable membrane has a support layer on only one side thereof, the support layer may be a single layer or multiple layers.
When a waterproof sound-permeable membrane has support layers on both sides, one side can be a single layer and the other side can also be a single layer. In this case, both sides can be the same layer or different layers made of different types of materials.

When a waterproof sound-permeable membrane has support layers on both sides, one side can be a single layer and the other side can be multiple layers. It is also possible for the support layers on both sides to be multiple layers.

If the support layer is a single layer, it is preferable that the support layer be made of a layer using a sheet with a compressive stress of 600 kPa or less and be laminated to the waterproof sound-permeable membrane. If the support layer is made of multiple layers, it is preferable that at least one layer be made of a layer using a sheet with a compressive stress of 600 kPa or less. This can improve the waterproofness of the boundary between the waterproof sound-permeable membrane and the support layer.

A layer made of a sheet made of a soft material with a compressive stress of 600 kPa or less reduces the compressive stress of the entire waterproof sound-permeable component by 40%, and when incorporated into a housing with a high compression ratio, it can reduce the force applied to the waterproof sound-permeable membrane and reduce acoustic loss.

When the support layer is made up of multiple layers, as described above, it is preferable that at least one layer is a layer using a sheet with a compressive stress of 600 kPa or less. A sheet containing primarily a sheet layer made of the above-mentioned synthetic resin porous material can be preferably used as the layer using a sheet with a compressive stress of 600 kPa or less.

More specifically, sheets with a compressive stress of 600 kPa or less can be, for example, sheets primarily made of a sheet layer of porous polyolefin resin material, preferably having a compressive stress of approximately 50 to 300 kPa, or sheets primarily made of a porous polyurethane resin material or porous polyacrylic resin material, preferably having a compressive stress of approximately 0.1 to 100 kPa. Alternatively, a waterproof adhesive layer with an adhesive layer and/or a cushion layer without an adhesive layer can be used.

By combining layers with and without adhesive layers, or various layers with different compressive stresses, or by using a spacer layer as appropriate, it is possible to design a support layer with the desired compressive stress and thickness. By combining these with an appropriate waterproof sound-permeable membrane, a waterproof sound-permeable component can be obtained that requires a stress of 1 to 600 kPa to compress the waterproof sound-permeable membrane by 40% in the direction perpendicular to the membrane surface.

The waterproof sound-transmitting member of the present invention can be produced by laminating the sheets, films, membranes, etc. that make up each layer into the desired shape based on the above design. Examples of lamination methods include laminating each layer using known means such as pressure bonding.

The multi-layer structure may include one or more waterproof adhesive layers or cushion layers, which may be combined with one or more spacer layers as needed. It may also be possible to laminate two or more waterproof adhesive layers of different types, two or more cushion layers of different types, or a combination of waterproof adhesive layers and cushion layers, which may further be combined with one or more spacer layers as needed.
It is preferable that at least one of the layers constituting the support layer is a waterproof adhesive layer.

More specifically, a support layer containing a layer (preferably a waterproof adhesive layer or cushion layer) made of the same or different types of sheet with a compressive stress of 600 kPa or less is laminated on one or both sides of the waterproof sound-permeable membrane. A spacer layer (preferably a waterproof adhesive tape with a core made of non-porous synthetic resin such as non-porous PET, or a non-porous synthetic resin film such as non-porous PET film) may be laminated to the support layer as needed.

When a spacer layer is formed between the waterproof sound-transmitting membrane and the layer made of a sheet with a compressive stress of 600 kPa or less contained in the support layer, the layer structure of the entire waterproof sound-transmitting component is stabilized. Spacer layers can also be provided on both sides of the layer made of a sheet with a compressive stress of 600 kPa or less contained in the support layer, sandwiching the two together, further stabilizing the layer structure of the entire waterproof sound-transmitting component.

Preferred examples of the waterproof sound-permeable membrane and the support layer are shown below, but the present invention is not limited to these.
- A waterproof adhesive layer is placed on one side of the waterproof sound-permeable membrane, and the same or a different waterproof adhesive layer is placed on the other side.
- A waterproof adhesive layer or spacer layer is placed on one side of the waterproof sound-permeable membrane, and a cushion layer is placed on the other side.
A waterproof adhesive layer or spacer layer is placed on one side of the waterproof sound-permeable membrane, and a spacer layer is placed on the opposite side that comes into contact with the waterproof sound-permeable membrane, and then a waterproof adhesive layer or cushion layer is laminated on top.
- A waterproof adhesive layer or spacer layer is placed on one side of the waterproof sound-permeable membrane, and a spacer layer is placed on the opposite side that comes into contact with the waterproof sound-permeable membrane, and then a waterproof adhesive layer or cushion layer is laminated on top of that, and then a spacer layer is laminated again.

The thickness of the support layer (the thickness of that layer if it is a single layer, or the total thickness of the constituent layers if it is composed of multiple layers) is not particularly limited, but is preferably 30 to 3,000 μm, more preferably 100 to 1,500 μm, even more preferably 300 to 1,000 μm, and particularly preferably 500 to 800 μm.

Of these, the thickness of one layer using a sheet with a compressive stress of 600 kPa or less is the same as in the case of a single layer, preferably 30 to 3000 μm, more preferably 100 to 1500 μm.

Of the layers constituting the support layer, it is preferable that the total thickness of layers using sheets with a compressive stress of 600 kPa or less account for 30% or more of the total thickness of the waterproof sound-transmitting member, more preferably 40% or more, and particularly preferably 50% or more.

When layers using sheets with a compressive stress of 600 kPa or less are provided on both sides of a waterproof sound-permeable membrane, it is desirable that the total thickness of the layers using sheets with a compressive stress of 600 kPa or less should preferably be 60% or more of the total thickness of the waterproof sound-permeable member, more preferably 70 to 98%, even more preferably 85 to 98%, and particularly preferably 90 to 96%.

When a layer using a sheet with a compressive stress of 600 kPa or less is provided on only one side of the waterproof sound-transmitting membrane, it is desirable that the total thickness of the layer using the sheet with a compressive stress of 600 kPa or less is preferably 40% or more, more preferably 50% or more, even more preferably 50 to 70%, and particularly preferably 50 to 60% of the total thickness of the waterproof sound-transmitting member.
Here, the thickness of the waterproof sound-transmitting member refers to the thickness of the thickest part of the waterproof sound-transmitting member including the waterproof sound-transmitting membrane and the support layer.

(ii) Shape of the support layer When supporting layers are laminated on both sides of the waterproof sound-permeable membrane, it is preferable that the laminated support layers on both sides have the same shape and are positioned so that they overlap when viewed from the perpendicular direction to the waterproof sound-permeable membrane surface, as this makes it difficult for compressive forces to be transmitted to the waterproof sound-permeable membrane.

It is preferable for the support layer to be laminated around the periphery of the waterproof sound-permeable membrane, as this does not interfere with the vibration of the waterproof sound-permeable membrane. Furthermore, it is preferable for the shape of the support layer to have a constant cross section in the horizontal direction (parallel to the membrane surface) relative to the waterproof sound-permeable membrane surface, as this makes it difficult for compressive forces to be transmitted to the waterproof sound-permeable membrane.

In order to make it difficult for the stress applied by compression of the waterproof sound-transmitting member to be biased, reduce distortion in the sound-transmitting region of the waterproof sound-transmitting membrane, and reduce acoustic loss, it is preferable that the area (of the cross section parallel to the membrane surface) of the support layer laminated to the waterproof sound-transmitting membrane be 1 ^mm2 or more, and more preferably 5 ^mm2 or more.

On the other hand, in order to contribute to the miniaturization of electrical appliances by saving space and to reduce the load on the housing by reducing the force required for compression, it is preferable that the area of the support layer laminated on the waterproof sound-permeable membrane be 50 ^mm2 or less, and more preferably 30 ^mm2 or less.

3. Sound-transmitting area In a waterproof sound-transmitting component consisting of a waterproof sound-transmitting membrane and a support layer laminated around its periphery, sound passes through the part where the support layer is not laminated and the waterproof sound-transmitting membrane is exposed, i.e., the sound-transmitting area of the waterproof sound-transmitting membrane.

The wider the sound-passing region, the smaller the acoustic loss, so the area of the sound-passing region is preferably 0.5 mm ² or more, and more preferably 1.5 mm ² or more. On the other hand, the smaller the area, the more stable the shape becomes and the less likely it is to be distorted, and the smaller the acoustic loss during compression, so the area of the sound-passing region is preferably 40 mm ² or less, and more preferably 20 mm ² or less.

The planar shape of the sound-permeable area is preferably circular or a similar shape, as this is more stable and less prone to distortion, and the circularity calculated using formula (1) is preferably 0.45 to 1, and more preferably 0.6 to 1. It is also preferable that the area has no corners.

(Equation 1)
Circularity = 4 × pi × area ÷ [perimeter] ² ... Formula (1)

Figure 2 shows an example of the configuration of the waterproof sound-transmitting member of the present invention. The waterproof sound-transmitting member 1 of the present invention is preferably circular, and a support layer 3 is laminated on one or both sides of the waterproof sound-transmitting membrane 2 so as to be formed around the periphery of the sound-transmitting area 4.

The present invention will be described in more detail below using examples, but the present invention is not limited to the following examples. Note that the physical properties in the following examples and comparative examples were measured and evaluated according to the following methods.

(1) Acoustic Loss Measurement of acoustic loss will be described with reference to Fig. 3. Inside an anechoic box 16, a speaker 11 emitted a TSP signal with a sound pressure of 94 dB, including a frequency of 1 kHz, and the output of a MEMS (ADMP401) analog microphone 12 built into a microphone jig 13 was converted into a digital signal by an analyzer and analyzed using analysis software (CLIO Pocket manufactured by Audiomatica) to measure the sound pressure level at a frequency of 1 kHz.

The microphone fixture 13 is a metal box-shaped device with an opening 14 on the outer surface through which sound can enter, a waterproof sound-transmitting member mounting section with a specified gap, and an internal space 15 that is sealed by mounting the waterproof sound-transmitting member 1, and a MEMS analog microphone 12 is placed in the internal space 15.

The speaker 11, opening 14, waterproof sound-transmitting member 1, and MEMS analog microphone 12 are arranged in a straight line without being obstructed by the structure of the microphone jig 13. The opening 14 is circular and has a diameter of 1 mm, the distance from the waterproof sound-transmitting member 1 in the internal space 15 to the MEMS analog microphone 12 is 6 mm, and the volume of the internal space is 27 ^mm3 .

The microphone jig 13 was positioned 4.5 cm from the speaker 11 so that the plane with the opening 14 was parallel to the sound-producing part of the speaker (so that the sound was incident perpendicularly).

The difference between the sound pressure level measured using only the microphone jig and the sound pressure level measured with a waterproof sound-permeable material attached to the opening of the microphone jig was calculated as acoustic loss. The lower the acoustic loss, the higher the sound permeability.

The gap between the waterproof sound-transmitting member mounting sections was adjusted appropriately, and the acoustic loss of the waterproof sound-transmitting member was measured at a compression rate of 0% and a compression rate of 40%. ΔdBV was calculated by subtracting the acoustic loss at a compression rate of 0% from the acoustic loss at a compression rate of 40%. The smaller this value, the more suppressed the increase in acoustic loss due to compression. Measurements were performed on 10 samples, and the average value and standard deviation were calculated.

(2) Tensile test A test piece measuring 50 mm wide x 80 mm long was attached to a tensile tester (product name "Autograph AG-IS type", manufactured by Shimadzu Corporation) with a grip spacing of 50 mm, and a tensile test was performed at a tensile speed of 150 mm/min. The measurement temperature was 22°C and the measurement humidity was 65%. The initial slope of the obtained stress-strain curve was divided by the cross-sectional area (mm ² ) of the waterproof sound-permeable membrane to calculate the tensile modulus (MPa). The above measurement was performed 10 times in total, 5 times each, with the test piece rotated 90° vertically and horizontally, and the average value was calculated.

(3) Water Pressure Resistance Measurement was performed in accordance with JIS L 1092B method (high water pressure method). However, since the measurement area of the waterproof sound-transmitting member was insufficient, the waterproof sound-transmitting member was attached to a SUS plate with a circular hole, and water leakage was judged at one point. When measuring the waterproof sound-transmitting membrane, in order to prevent rupture due to membrane deformation, a plain weave fabric, which is less likely to affect the water pressure resistance of the porous membrane, was placed on the side opposite to the surface to which water pressure was applied. The plain weave fabric was woven using 80 dtex/24 filament 6 nylon multifilament yarn for the warp and 80 dtex/34 filament 6 nylon multifilament yarn for the weft, with a warp density of 120 threads/2.54 cm and a weft density of 90 threads/2.54 cm.

(4) Thickness Using a scanning electron microscope (S-3000N manufactured by Hitachi High-Technologies Corporation), vertical cross-sectional photographs were taken at 300 to 5000 magnifications to measure the thickness of the waterproof sound-transmitting member.

(5) Compressive stress Using a compression testing machine (KES-G5 manufactured by Kato Tech Co., Ltd.), the waterproof sound-transmitting member 1 used in the examples was installed as shown in FIG. 4, and the parallel plate 17 was moved in the compression direction 18 (perpendicular to the membrane surface of the waterproof sound-transmitting membrane) and a load was applied. The force required to compress 40% of the maximum thickness of the waterproof sound-transmitting member (the sum of the thicknesses of the support layer and the waterproof sound-transmitting membrane) was measured, and the stress was calculated by dividing the force by the area of the support layer (the area overlapping in the vertical direction). A 2 cm ² circular attachment was used as the measurement section, and the compression speed was 0.01 mm / min. Measurements were performed on five samples, and the average value was calculated.

The individual compressive stresses of the cushioning material, double-sided adhesive waterproof tape, and non-porous PET film used in the support layer were measured using samples cut into 2.5 mm x 2.5 mm = 6.25 ^mm2 in advance. Each measurement was performed on five samples, and the average value was calculated.

In addition, since it is difficult to compress non-porous PET or those using only non-porous PET as the core material by 40%, it was difficult to achieve a value of 1569 kPa or more, which is the upper limit of measurement for a sample size of 6.25 ^mm2 .

[Example 1]
A polyurethane resin solution having the following formulation was prepared.
<Prescription>
MP865PS: 100 parts by mass (manufactured by DIC Corporation, polyurethane resin, solid content 30% by mass, 100% modulus 11 MPa)
Leatheroid LU2850M: 65 parts by mass (manufactured by Dainichiseika Color & Chemicals Mfg. Co., Ltd., silica fine particle dispersion, solid content 20% by mass)
Dilac Black L1584: 4 parts by mass (DIC Corporation, black pigment, solid content 25% by mass)
N,N-dimethylformamide: 28 parts by mass

Next, the polyurethane resin solution was applied to a release substrate using a knife-on-roll coater to a coating thickness that would result in a waterproof sound-transmitting membrane of 30 μm in thickness. It was then immersed in 20°C water for 1.5 minutes to allow for complete solidification. After washing in 50°C warm water for 5 minutes, it was heat-treated at 130°C for 2 minutes and dried, and the release substrate was removed to obtain a waterproof sound-transmitting membrane. The tensile modulus of the waterproof sound-transmitting membrane was measured to be 3.9 MPa, the water pressure resistance was 70 kPa, and the air permeability was 19 seconds/100 mL.

The waterproof sound-permeable membrane was punched out using a Thomson die into a rectangle with a long side length of 4.4 mm and a short side length of 3.4 mm. The support layer was punched out using a Thomson die into a rectangle with a long side length of 4.4 mm and a short side length of 3.4 mm, with an elliptical opening in the center with a long axis diameter of 2.4 mm and a short axis diameter of 1.4 mm.

The support layers used were double-sided adhesive waterproof tape 1 (manufactured by Sekisui Chemical Co., Ltd., product name "5225VSB"; porous polyethylene; thickness 250 μm) and double-sided adhesive waterproof tape 2 (manufactured by Sekisui Chemical Co., Ltd., product name "5240VSB"; porous polyethylene; thickness 400 μm).

A waterproof sound-transmitting member was produced by laminating and pressing the double-sided adhesive waterproof tape 1, the waterproof sound-transmitting membrane, and the double-sided adhesive waterproof tape 2 in that order. The waterproof sound-transmitting member had a thickness of 680 μm. The sound-transmitting region had an area of 2.64 mm ² and a circularity of 0.9, and the area of the support layer was 12.3 mm ² .

The stress required to compress double-sided adhesive waterproof tape 1 by 40% was 111 kPa, and the stress required to compress double-sided adhesive waterproof tape 2 by 40% was 175 kPa. Double-sided adhesive waterproof tape 1 accounted for 36.8% of the total thickness of the waterproof sound-transmitting component, and double-sided adhesive waterproof tape 2 accounted for 58.8% of the total thickness of the waterproof sound-transmitting component, for a total of 95.6%.

The acoustic loss, water pressure resistance, and stress required for 40% compression of the waterproof sound-transmitting member were measured at compression rates of 0% and 40%, and the results are shown in Table 1.
By using a waterproof sound-transmitting member that requires a small stress to compress it by 40%, acoustic loss was less likely to increase even when it was compressed by 40% using a waterproof sound-transmitting membrane with a low tensile modulus of elasticity.

[Example 2]
The support layer was made of a double-sided adhesive waterproof tape 1 (manufactured by Sekisui Chemical Co., Ltd., trade name "5225VSB"; thickness 250 μm), two layers of double-sided adhesive waterproof tape 3 (manufactured by Nitto Denko Corporation, trade name "No. 5601"; non-porous PET; thickness 10 μm), and a cushion material 1 (manufactured by Inoac Corporation, trade name "PORON SR-S15P"; porous polyurethane resin + PET; thickness 500 μm). Except for the double-sided adhesive waterproof tape 1, waterproof sound-transmitting membrane, double-sided adhesive waterproof tape 3, cushion material 1, and double-sided adhesive waterproof tape 3 laminated in this order, a waterproof sound-transmitting member was produced in the same manner as in Example 1. The thickness of the waterproof sound-transmitting member was 800 μm.

The stress required to compress the double-sided waterproof tape 1 by 40% is 111 kPa, and the stress required to compress the cushion material 1 by 40% is 0.2 kPa. Since the core material of the double-sided waterproof tape 3 is non-porous PET, and it is difficult to compress it by 40%, it is clear that the stress required to compress the double-sided waterproof tape 3 by 40% is at least 1569 kPa, which is the upper limit of measurement for a sample size of 6.25 ^mm2 .

The double-sided adhesive waterproof tape 1 accounted for 31.2% of the total thickness of the waterproof sound-transmitting component, and the cushioning material 1 accounted for 62.5% of the total thickness of the waterproof sound-transmitting component, for a total of 93.7%.

The results of measuring the acoustic loss, water pressure resistance, and stress required for 40% compression of the waterproof sound-transmitting member at compression rates of 0% and 40% are shown in Table 1.
By using a waterproof sound-transmitting member that requires a small stress to be compressed by 40%, acoustic loss was less likely to increase even when a waterproof sound-transmitting membrane with a low tensile modulus was used and compressed by 40%.

[Example 3]
The support layer was made of a double-sided adhesive waterproof tape 1 (manufactured by Sekisui Chemical Co., Ltd., product name "5225VSB"; thickness 250 μm), two layers of a double-sided adhesive waterproof tape 3 (manufactured by Nitto Denko Corporation, product name "No. 5601"; thickness 10 μm), and a cushion material 2 (manufactured by Inoac Corporation, product name "PORON SR-S40P"; porous polyurethane resin + PET; thickness 400 μm). A waterproof sound-transmitting member was produced in the same manner as in Example 1, except that the double-sided adhesive waterproof tape 1, waterproof sound-transmitting membrane, double-sided adhesive waterproof tape 3, cushion material 2, and double-sided adhesive waterproof tape 3 were laminated in this order. The thickness of the waterproof sound-transmitting member was 700 μm.

The stress required to compress double-sided adhesive waterproof tape 1 by 40% was 111 kPa, and the stress required to compress cushion material 2 by 40% was 1 kPa. The stress required to compress double-sided adhesive waterproof tape 3 by 40% was 1569 kPa or more. Double-sided adhesive waterproof tape 1 accounted for 35.7% of the total thickness of the waterproof sound-transmitting component, and cushion material 2 accounted for 57.1% of the total thickness of the waterproof sound-transmitting component, for a total of 92.8%.

The acoustic loss, water pressure resistance, and stress required for 40% compression of the waterproof sound-transmitting member were measured at compression rates of 0% and 40%, and the results are shown in Table 1.
By using a waterproof sound-transmitting member that requires a small stress to be compressed by 40%, acoustic loss was less likely to increase even when a waterproof sound-transmitting membrane with a low tensile modulus was used and compressed by 40%.

[Example 4]
The support layer was made of a double-sided adhesive waterproof tape 1 (manufactured by Sekisui Chemical Co., Ltd., product name "5225VSB"; thickness 250 μm), two layers of a double-sided adhesive waterproof tape 3 (manufactured by Nitto Denko Corporation, product name "No. 5601"; thickness 10 μm), and a cushion material 3 (manufactured by Iwatani Corporation, product name "ISR-ACF-TH"; porous acrylic resin; thickness 400 μm). A waterproof sound-transmitting member was produced in the same manner as in Example 1, except that the double-sided adhesive waterproof tape 1, waterproof sound-transmitting membrane, double-sided adhesive waterproof tape 3, cushion material 3, and double-sided adhesive waterproof tape 3 were laminated in this order. The thickness of the waterproof sound-transmitting member was 700 μm.

The stress required to compress the double-sided adhesive waterproof tape 1 by 40% was 111 kPa, and the stress required to compress the cushion material 3 by 40% was 2 kPa. The stress required to compress the double-sided adhesive waterproof tape 3 by 40% was 1569 kPa or more. The double-sided adhesive waterproof tape 1 accounted for 35.7% of the total thickness of the waterproof sound-transmitting component, and the cushion material 3 accounted for 57.1% of the total thickness of the waterproof sound-transmitting component, for a total of 92.8%.

The acoustic loss, water pressure resistance, and stress required for 40% compression of the waterproof sound-transmitting member were measured at compression rates of 0% and 40%, and the results are shown in Table 1.
By using a waterproof sound-transmitting member that requires a small stress to be compressed by 40%, acoustic loss was less likely to increase even when a waterproof sound-transmitting membrane with a low tensile modulus was used and compressed by 40%.

[Example 5]
The waterproof sound-transmitting membrane is a circle with a diameter of 4 mm, the support layer is a circle with a diameter of 4 mm and a circular opening with a diameter of 2.2 mm in the center, and the support layer is made of a double-sided adhesive waterproof tape 4 (manufactured by Nitto Denko Corporation, product name "No. 5615"; non-porous PET; thickness 150 μm), a double-sided adhesive waterproof tape 5 (manufactured by Nitto Denko Corporation, product name "No. 5605"; non-porous PET; thickness 50 μm), two layers of a cushion material 2 (manufactured by Inoac Corporation, product name "PORON SR-S40P"; porous polyurethane resin + PET; thickness 400 μm), and a 50 μm thick PET film. Except for the double-sided adhesive waterproof tape 4, waterproof sound-transmitting membrane, double-sided adhesive waterproof tape 5, PET film, double-sided adhesive waterproof tape 5, and cushion material 2 laminated in this order, a waterproof sound-transmitting member was produced in the same manner as in Example 1. The thickness of the waterproof sound-transmitting member was 730 μm. The sound-permeable region had an area of 3.8 mm ² and a circularity of 1, and the area of the support layer was 8.8 mm ² .

The stress required to compress cushion material 2 by 40% was 1 kPa. The stress required to compress double-sided adhesive waterproof tape 4, double-sided adhesive waterproof tape 5, and 50 μm thick PET film by 40% was 1569 kPa or more for each. Cushion material 2 accounted for 54.8% of the total thickness of the waterproof sound-transmitting member.

The results of measuring the acoustic loss, water pressure resistance, and stress required for 40% compression of the waterproof sound-transmitting member at compression rates of 0% and 40% are shown in Table 1.
By using a waterproof sound-transmitting member that requires a small stress to be compressed by 40%, acoustic loss was less likely to increase even when a waterproof sound-transmitting membrane with a low tensile modulus was used and compressed by 40%.

[Example 6]
A waterproof sound-transmitting member was produced in the same manner as in Example 5, except that the support layer was a circle with a diameter of 6 mm and had a circular opening with a diameter of 2.2 mm at its center. The thickness of the waterproof sound-transmitting member was 730 μm. The sound-transmitting region had an area of 3.8 mm ² and a circularity of 1, and the area of the support layer was 24.5 mm ² .

The stress required to compress cushion material 2 by 40% was 1 kPa. Cushion material 2 accounted for 54.8% of the total thickness of the waterproof sound-permeable member.

The results of measuring the acoustic loss, water pressure resistance, and stress required for 40% compression of the waterproof sound-transmitting member at compression rates of 0% and 40% are shown in Table 1.
By using a waterproof sound-transmitting member that requires a small stress to compress it by 40%, acoustic loss was less likely to increase even when it was compressed by 40% using a waterproof sound-transmitting membrane with a low tensile modulus of elasticity.

[Example 7]
The support layer was made of a double-sided adhesive waterproof tape 4 (manufactured by Nitto Denko Corporation, trade name "No. 5615"; thickness 150 μm), two layers of a double-sided adhesive waterproof tape 5 (manufactured by Nitto Denko Corporation, trade name "No. 5605"; thickness 50 μm), a cushion material 4 (manufactured by Inoac Corporation, trade name "PORON SR-S20P"; porous polyurethane + PET; thickness 400 μm), and a 50 μm thick PET film. A waterproof sound-transmitting member was produced in the same manner as in Example 5, except that the double-sided adhesive waterproof tape 4, waterproof sound-transmitting membrane, double-sided adhesive waterproof tape 5, PET film, double-sided adhesive waterproof tape 5, and cushion material 4 were laminated in this order. The thickness of the waterproof sound-transmitting member was 730 μm.

The stress required to compress cushion material 4 by 40% was 0.2 kPa. Cushion material 4 accounted for 54.8% of the total thickness of the waterproof sound-transmitting member.

The acoustic loss, water pressure resistance, and stress required for 40% compression of the waterproof sound-transmitting member were measured at compression rates of 0% and 40%, and the results are shown in Table 1.
By using a waterproof sound-transmitting member that requires a small stress to be compressed by 40%, acoustic loss was less likely to increase even when a waterproof sound-transmitting membrane with a low tensile modulus was used and compressed by 40%.

[Example 8]
A waterproof sound-transmitting member was produced in the same manner as in Example 7, except that the support layer was a circle with a diameter of 6 mm and had a circular opening with a diameter of 2.2 mm at its center. The thickness of the waterproof sound-transmitting member was 730 μm. The sound-transmitting region had an area of 3.8 mm ² and a circularity of 1, and the area of the support layer was 24.5 mm ² .

The stress required to compress cushion material 4 by 40% was 0.2 kPa. Cushion material 4 accounted for 54.8% of the total thickness of the waterproof sound-transmitting member.

The results of measuring the acoustic loss, water pressure resistance, and stress required for 40% compression of the waterproof sound-transmitting member at compression rates of 0% and 40% are shown in Table 1.
By using a waterproof sound-transmitting member that requires a small stress to be compressed by 40%, acoustic loss was less likely to increase even when a waterproof sound-transmitting membrane with a low tensile modulus was used and compressed by 40%.

[Example 9]
A waterproof sound-transmitting member was produced in the same manner as in Example 1, except that a double-sided adhesive waterproof tape 1 (manufactured by Sekisui Chemical Co., Ltd., product name "5225VSB"; thickness 250 μm) and a double-sided adhesive waterproof tape 6 (manufactured by Sekisui Chemical Co., Ltd., product name "5230VSB"; porous polyethylene; thickness 300 μm) were used as the support layer, and the waterproof sound-transmitting member was laminated in this order. The thickness of the waterproof sound-transmitting member was 580 μm.

The stress required to compress double-sided adhesive waterproof tape 6 by 40% was 234 kPa. The stress required to compress double-sided adhesive waterproof tape 1 by 40% was 111 kPa. Double-sided adhesive waterproof tape 6 accounted for 51.7% of the total thickness of the waterproof sound-transmitting component, and double-sided adhesive waterproof tape 1 accounted for 43.1% of the total thickness of the waterproof sound-transmitting component, for a total of 94.8%.

The acoustic loss, water pressure resistance, and stress required for 40% compression of the waterproof sound-transmitting member were measured at compression rates of 0% and 40%, and the results are shown in Table 1.
By using a waterproof sound-transmitting member that requires a small stress to be compressed by 40%, acoustic loss was less likely to increase even when a waterproof sound-transmitting membrane with a low tensile modulus was used and compressed by 40%.

[Comparative Example 1]
A waterproof sound-transmitting member was produced in the same manner as in Example 1, except that a double-sided adhesive waterproof tape 7 (manufactured by Sekisui Chemical Co., Ltd., product name "5230SKB"; porous polyethylene; thickness 300 μm) and a double-sided adhesive waterproof tape 8 (manufactured by Sekisui Chemical Co., Ltd., product name "5225SKB"; porous polyethylene; thickness 250 μm) were used as the support layer, and the double-sided adhesive waterproof tape 7, waterproof sound-transmitting membrane, and double-sided adhesive waterproof tape 8 were laminated in this order. The stress required to compress the double-sided adhesive waterproof tape 7 by 40% was 780 kPa. The stress required to compress the double-sided adhesive waterproof tape 8 by 40% was 682 kPa. The thickness of the waterproof sound-transmitting member was 580 μm.

The acoustic loss, water pressure resistance, and stress required for 40% compression of the waterproof sound-transmitting member were measured at compression rates of 0% and 40%, and the results are shown in Table 1.
Because the stress required for 40% compression is large, when a waterproof sound-permeable membrane with a low tensile modulus was used and compressed to 40%, the acoustic loss increased, making it unsuitable for use in compression.

[Comparative Example 2]
A waterproof sound-transmitting member was produced in the same manner as in Example 1, except that two layers of double-sided adhesive waterproof tape 7 (manufactured by Sekisui Chemical Co., Ltd., product name "5230SKB"; porous polyethylene; thickness 300 μm) were used as the support layer, and the double-sided adhesive waterproof tape 7, waterproof sound-transmitting membrane, and double-sided adhesive waterproof tape 7 were laminated in this order. The stress required to compress the double-sided adhesive waterproof tape 7 by 40% was 780 kPa. The thickness of the waterproof sound-transmitting member was 630 μm.

The results of measuring the acoustic loss, water pressure resistance, and stress required for 40% compression of the waterproof sound-transmitting member at compression rates of 0% and 40% are shown in Table 1.
Because the stress required for 40% compression is large, when a waterproof sound-permeable membrane with a low tensile modulus was used and compressed to 40%, the acoustic loss increased, making it unsuitable for use in compression.

The materials used in the above examples and comparative examples are as follows:
Double-sided adhesive waterproof tape 1: Sekisui Chemical Co., Ltd., product name "5225VSB" (porous polyethylene: thickness 250 μm)
Double-sided adhesive waterproof tape 2: Sekisui Chemical Co., Ltd., product name "5240VSB" (porous polyethylene: thickness 400 μm)

Double-sided adhesive waterproof tape 3: manufactured by Nitto Denko Corporation, product name "No. 5601" (non-porous PET film: thickness 10 μm)
Double-sided adhesive waterproof tape 4: manufactured by Nitto Denko Corporation, product name "No. 5615" (non-porous PET film: thickness 150 μm)

Double-sided adhesive waterproof tape 5: manufactured by Nitto Denko Corporation, product name "No. 5605" (non-porous PET film: thickness 50 μm)
Double-sided adhesive waterproof tape 6: product name "5230VSB" (porous polyethylene: thickness 300 μm), manufactured by Sekisui Chemical Co., Ltd.

Double-sided adhesive waterproof tape 7: Sekisui Chemical Co., Ltd., product name "5230SKB" (porous polyethylene: thickness 300 μm)
Double-sided adhesive waterproof tape 8: Sekisui Chemical Co., Ltd., product name "5225SKB" (porous polyethylene: thickness 250 μm)

Cushion material 1: Inoac Corporation, product name "PORON SR-S15P" (porous polyurethane resin 450 μm + non-porous PET 50 μm: total thickness 500 μm)
Cushion material 2: manufactured by Inoac Corporation, product name "PORON SR-S40P (porous polyurethane resin 350 μm + non-porous PET 50 μm: total thickness 400 μm)

Cushion material 3: Iwatani Corporation, product name "ISR-ACF-TH (porous acrylic resin; thickness 400 μm)
Cushion material 4: manufactured by Inoac Corporation, product name "PORON SR-S20P (porous polyurethane resin 350 μm + non-porous PET 50 μm: total thickness 400 μm)

Double-sided adhesive waterproof tapes 1, 2, and 6 and cushioning materials 1, 2, 3, and 4 correspond to the "sheets requiring a stress of 600 kPa or less to compress 40% in the vertical direction" of this invention. Double-sided adhesive waterproof tapes 3, 4, and 5 correspond to the spacer layer.

The waterproof sound-transmitting member of the present invention is highly waterproof, and even when compressed to prevent sound interference within the housing, it has low acoustic loss and does not impair the acoustic characteristics of microphones or speakers. Therefore, the waterproof sound-transmitting member of the present invention can be ideally used to provide waterproof protection for microphones and speakers in electrical appliances.

1: Waterproof sound-transmitting member 2: Waterproof sound-transmitting membrane 3: Support layer 4: Sound-transmitting area 11: Speaker 12: MEMS analog microphone 13: Microphone jig 14: Opening 15: Internal space 16: Anechoic box 17: Parallel plate 18: Compression direction

Claims (13)

A waterproof sound-transmitting member in which a support layer is laminated on at least one side of a waterproof sound-transmitting membrane, the waterproof sound-transmitting membrane having exposed sound-transmitting regions on both sides, the stress required to compress the waterproof sound-transmitting membrane by 40% in a direction perpendicular to the membrane surface being 1 to 600 kPa, and the waterproof sound-transmitting membrane being a porous membrane . The waterproof sound-permeable member according to claim 1, wherein the support layer is composed of a single layer or multiple layers, and includes a layer made of a sheet having a stress of 600 kPa or less required for 40% compression in at least the vertical direction. The waterproof sound-transmitting member according to claim 2, wherein the sheet requiring a stress of 600 kPa or less to compress 40% in the vertical direction includes a sheet layer made of a synthetic resin porous material. The waterproof sound-transmitting member according to claim 3, characterized in that the synthetic resin porous material is a porous synthetic resin material selected from the group consisting of polyolefin resin, polyurethane resin, and acrylic resin. A waterproof sound-transmitting member according to any one of claims 2 to 4, wherein, among the layers constituting the support layer, layers using sheets for which the stress required for 40% compression in the vertical direction is 600 kPa or less account for 40% or more of the overall thickness of the waterproof sound-transmitting member. The waterproof sound-permeable member according to claim 1, characterized in that the waterproof sound-permeable membrane has a tensile modulus of elasticity of 0.5 to 20 MPa. The waterproof sound-permeable member according to claim 1, characterized in that the waterproof sound-permeable membrane contains a material with a 100% modulus of 1 to 20 MPa. The waterproof sound-permeable member according to claim 1, wherein the waterproof sound-permeable membrane has an air permeability of 3 to 500 seconds/100 mL according to the JIS L 1096 Gurley method. The waterproof sound-permeable member according to claim 1, wherein the waterproof sound-permeable membrane has a thickness of 15 to 80 μm. The waterproof sound-permeable member according to claim 1, characterized in that the waterproof sound-permeable membrane is made of polyurethane resin. The waterproof sound-transmitting member according to claim 1, wherein the area of the support layer laminated on at least one side of the waterproof sound-transmitting membrane is 1 to 50 mm ² . The waterproof sound-transmitting member according to claim 1, wherein the sound-transmitting region satisfies at least one of the following conditions a) and b).
a) The planar shape has no corners and the circularity is 0.45 to 1. b) The area is 0.5 to 40 ^mm2 . The waterproof sound-transmitting member according to claim 1, wherein the support layer satisfies at least one of the following conditions c) and d).
c) It is laminated on both sides of the waterproof sound-permeable membrane. d) It is laminated on the periphery of the waterproof sound-permeable membrane.