Waterproof sound-transmitting materials

Abstract

[Problem] To provide is a water-resistant sound transmitting member which has a high degree of water resistance, which can be suitably used for the water-resistance protection of a microphone and a speaker for an electrical appliance, and with which, even when used in a compressed state in order to prevent sound interference within a housing, acoustic loss is low and the acoustic characteristics of a microphone and a speaker are not impaired.　[Solution] In this water-resistant sound transmitting member, a support layer is layered on at least one surface of a water-resistant sound transmitting film, a sound transmitting region where both surfaces of the water-resistant sound transmitting film are exposed is provided, and the stress on the film surface of the water-resistant sound transmitting member necessary to compress the same by 40% in the vertical direction is 1-600kPa.　

Description

[Technical Field]

[0001] The present invention relates to a waterproof sound-transmitting member that is resistant to increases in acoustic loss due to compression when assembled into a housing. [Background technology]

[0002] 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 term is used to include electronic products as well) have sound receiving and producing units such as microphones and speakers in their housing structures, with openings provided in the corresponding positions and sound being transmitted through these openings.

[0003] As exemplified by the widespread use of smartphones, these electrical appliances are increasingly used in outdoor environments and 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.

[0004] Conventionally, waterproof sound-transmitting members that have low acoustic loss while preventing water from entering the housing are attached to the openings in the sound-emitting unit and sound-receiving unit. The waterproof sound-transmitting member consists of a waterproof sound-transmitting membrane and a support layer laminated around its periphery, and has a sound-transmitting area where the waterproof sound-transmitting membrane is exposed.

[0005] The support layer maintains the shape of the component and bonds it to the housing, and sound is transmitted 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 seepage and sound leakage from the interface with the housing.

[0006] The acoustic loss of waterproof sound-transmitting components can be reduced by using soft materials for the waterproof sound-transmitting membrane and by reducing the basis weight. To reduce the basis weight, it is effective to select a material with a low specific gravity or to use a porous structure. However, waterproof sound-transmitting membranes made of soft materials and with a porous structure are easily deformed by compression.

[0007] Patent Document 1 discloses a waterproof sound-transmitting membrane that reduces sound loss by using a soft material such as polyurethane. Patent Document 2 discloses a waterproof sound-transmitting member that uses a soft material such as silicone rubber in the waterproof sound-transmitting membrane so that sound loss does not increase when water pressure is returned to normal pressure after it has been applied. Patent Document 3 discloses a waterproof sound-transmitting member that reduces distortion of transmitted sound by using a polyolefin resin foam in the support layer within the waterproof sound-transmitting member. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] WO2015 / 105052 [Patent Document 2] Japanese Patent Application Laid-Open No. 2014-7738 [Patent Document 3] Japanese Patent Application Laid-Open No. 2015-142282 Summary of the Invention [Problem to be solved by the invention]

[0009] Waterproof sound-transmitting membranes, which are made of soft materials 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 in a waterproof sound-transmitting component, distortion occurs when it is compressed and incorporated into a housing, increasing acoustic loss.

[0010] The waterproof sound-transmitting member disclosed in Patent Document 1, which uses a waterproof sound-transmitting membrane made of a soft material, is not suitable for incorporation into a housing with a high compression ratio.

[0011] In the waterproof sound-transmitting member using a waterproof sound-transmitting membrane made of a soft material disclosed in Patent Document 2, after the waterproof sound-transmitting membrane is distorted by water pressure, the distortion is eliminated and acoustic loss returns to normal when the pressure 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.

[0012] The waterproof sound-transmitting member disclosed in Patent Document 3, which uses a foam for the support layer, reduces sound distortion caused by interference with 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. Distortion of the waterproof sound-transmitting membrane when the waterproof sound-transmitting member is compressed and assembled is also not taken into consideration.

[0013] The present invention aims to provide a waterproof sound-transmitting member that can be used with a high compression ratio. In particular, the present invention aims to provide a waterproof sound-transmitting member 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. [Means for solving the problem]

[0014] After extensive research, the inventors discovered that by devising a combination of the waterproof sound-transmitting membrane and the support layer so that the stress required to compress the waterproof sound-transmitting member by 40% in the direction perpendicular to the membrane surface is 1 to 600 kPa, it is possible to reduce acoustic loss when used at high compression rates, and this led to the completion of the present invention.

[0015] 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, and the waterproof sound-transmitting membrane has an exposed sound-transmitting area on both sides, and the stress required to compress the waterproof sound-transmitting membrane by 40% in the direction perpendicular to the membrane surface is 1 to 600 kPa. and the waterproof sound-transmitting membrane is a porous membrane. A waterproof sound-transmitting member characterized by:

[0016] (2) The support layer is composed of a single layer or multiple layers, and includes a layer using a sheet whose stress required for compressing at least 40% in the vertical direction is 600 kPa or less, (1 ) notes The above waterproof and sound-permeable material.

[0017] (3) 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. (2)The waterproof sound-transmitting member described above. (4) The synthetic resin porous material is a porous synthetic resin material selected from the group consisting of polyolefin resins, polyurethane resins, and acrylic resins. (3) The waterproof sound-transmitting member described above.

[0018] (5) Among the layers constituting the support layer, the layer using a sheet with a stress of 600 kPa or less required for 40% compression in the vertical direction accounts for 40% or more of the thickness of the entire waterproof sound-transmitting member, (2) ~ (4) The waterproof sound-transmitting member according to any one of the preceding items. (6) The waterproof sound-permeable membrane has a tensile modulus of 0.5 to 20 MPa. ) The waterproof sound-transmitting member described above.

[0019] (7) The waterproof sound-permeable membrane is characterized in that it contains a material having a 100% modulus of 1 to 20 MPa. ) The waterproof sound-transmitting member described above. (8) The waterproof sound-permeable member according to (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.

[0020] (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 area of ​​the support layer laminated on at least one side of the waterproof sound-permeable membrane is 1 to 50 mm 2 (1 ) Waterproof sound-transmitting part Material.

[0021] (12) The waterproof sound-transmitting member according to (1), wherein the sound-transmitting area 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) Area 0.5 to 40 mm 2 Being (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 on the periphery of the waterproof sound-permeable membrane. and [Effects of the Invention]

[0022] 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. When excessive force is applied to the waterproof sound-transmitting membrane, distortion occurs, inhibiting vibrations caused by the incident sound and increasing acoustic loss.

[0023] 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 reducing acoustic loss. This technical effect can be more reliably achieved by optimally combining the material of the support layer, the material of the membrane, the shape of the member, etc.

[0024] In other words, by using a waterproof sound-permeable membrane that is easily deformed and has a relatively low tensile modulus, and by combining it with a support layer that has a certain thickness and a material with low compressive stress, it is possible to prevent an increase in acoustic loss due to compression when the membrane is installed in a housing. [Brief explanation of the drawings]

[0025] [Figure 1] 1 is a cross-sectional view of an example of the configuration of a waterproof sound-transmitting member of the present invention. [Figure 2] 1 is a plan view of an example of the configuration of a waterproof sound-transmitting member of the present invention. [Figure 3] FIG. 1 is a schematic diagram of an acoustic measurement device. [Figure 4] FIG. 1 is a schematic diagram of a compression test. DETAILED DESCRIPTION OF THE INVENTION

[0026] 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 surface 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 the direction perpendicular to the membrane surface is 1 to 600 kPa.

[0027] An example of the configuration of the waterproof sound-transmitting member of the present invention is shown in Figure 1. According to 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 as to be positioned around the periphery of a sound-transmitting region 4.

[0028] 1.Waterproof and sound-transmitting materials (1) Composition 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, the waterproof sound-transmitting membrane has an exposed area (=sound-transmitting area) on both sides where the support layer is not laminated.

[0029] In the waterproof sound-transmitting member of the present invention, sound is transmitted through this sound-transmitting region. The incident sound vibrates the waterproof sound-transmitting membrane and is transmitted to the opposite side. That is, in the waterproof sound-transmitting member of the present invention, a support layer is laminated on the part of the waterproof sound-transmitting membrane other than the sound-transmitting region.

[0030] (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) before being 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.

[0031] In order to reduce the force acting on the waterproof sound-transmitting membrane and thereby reduce acoustic loss when the waterproof sound-transmitting member is incorporated into a housing at a high compression rate, 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 600 kPa or less, preferably 400 kPa or less, and even more preferably 300 kPa or less.

[0032] On the other hand, by pressing and fixing the waterproof sound-transmitting member against the housing, the dissipation of energy due to 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.

[0033] An outline of the method for measuring compressive stress in the present invention is shown in Fig. 4. In Fig. 4, 1 is a waterproof sound-transmitting member, 17 is parallel plates, and 18 is a compression direction.

[0034] In general, a compression test is performed by sandwiching a test piece between two parallel plates in a compression testing machine and applying a load to determine the stress. In the present invention, the test piece (waterproof sound-transmitting member) is sandwiched between the 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 placed so that they each contact the parallel plates.

[0035] Then, the parallel plates are moved perpendicular to the membrane surface of the waterproof sound-transmitting 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-transmitting membrane, thereby applying a compressive force to the waterproof sound-transmitting member.

[0036] The "stress required for 40% compression" of 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.

[0037] 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 the shape is uniform. However, when multiple support layers are stacked and the 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).

[0038] For example, if the area of ​​the outermost layer of the support layer (the layer in contact with the parallel plate) is large and a smaller area is stacked on the inner layer, the stress acts on the area of ​​the inner layer that overlaps in the vertical direction, so the area of ​​the support layer is the area of ​​the inner layer.On the other hand, if the area of ​​the outermost layer of the support layer is small and a larger area is stacked on the inner layer, the stress acts on the area of ​​the outermost layer, so the area of ​​the support layer is the area of ​​the outermost layer.

[0039] 2.Waterproof sound-permeable membrane (1) Physical properties of the film 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 at least in a portion thereof. 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.

[0040] On the other hand, in order to reduce distortion due to compression of the waterproof sound-transmitting member and thereby reduce acoustic loss, the tensile modulus of elasticity of the waterproof sound-transmitting membrane is preferably 0.5 MPa or more, and more preferably 2 MPa or more.

[0041] To reduce the tensile modulus of elasticity of a waterproof sound-transmitting membrane, it is effective to use a soft material. The 100% modulus, which is an index of the softness of a material, is preferably 1 to 20 MPa. The 100% modulus of a material is a physical property of the material itself that constitutes the waterproof sound-transmitting membrane, and is not affected by the porous structure, etc. 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.

[0042] 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, more preferably 30 to 400 kPa. When the water pressure resistance is in the range of 10 to 400 kPa, high sound permeability and waterproofness can be obtained.

[0043] The waterproof sound-permeable membrane preferably has a breaking elongation of 100 to 500%, more preferably 150 to 400%, and particularly preferably 80 to 260%. If the breaking elongation is 100 to 500%, good sound permeability and sufficient waterproofness can be maintained.

[0044] The waterproof sound-permeable membrane preferably has an air permeability of 3 to 500 seconds / 100 mL, more preferably 3 to 300 seconds / 100 mL, according to the Gurley method of JIS L 1096. If the air permeability is 3 to 500 seconds / 100 mL, good sound permeability can be achieved.

[0045] The waterproof sound-permeable membrane of the present invention also has sound permeability such that the sound loss at a frequency of 1 kHz is less than 10 dB, the sound loss at a frequency of 2 kHz is less than 5 dB, and the sound loss at a frequency of 5 kHz is less than 5 dB.

[0046] (2) Membrane material The material that constitutes 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 100% modulus range (1 to 20 MPa) is used.

[0047] Specifically, it is preferable to use elastomers such as polyurethane resin and silicone rubber. In addition, the waterproof sound-transmitting membrane becomes softer when it is made into a porous membrane, so it is preferable to use a porous membrane. do. It is more preferable to use a porous polyurethane resin membrane because the structure can be easily controlled.

[0048] Examples of 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 of these may be mixed and used.

[0049] Here, the polyurethane resin is a resin obtained by polymerizing an isocyanate component and a polyol component.

[0050] 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. Specific examples of aromatic diisocyanates include xylylene diisocyanate, 4,4'-diphenylmethane diisocyanate, and tolylene diisocyanate. Specific examples of alicyclic diisocyanates include 1,4-cyclohexane diisocyanate, dicyclohexylmethane diisocyanate, and isophorone diisocyanate. Furthermore, trifunctional or higher isocyanates may be used as needed.

[0051] On the other hand, examples of the polyol component 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.

[0052] Various additives may be added to the polyurethane resin as needed, such as a water repellent, a crosslinking agent, inorganic fine particles, a plasticizer, an antioxidant, an ultraviolet absorber, a smoothing agent such as amide wax, a hydrolysis inhibitor, a pigment, an anti-yellowing agent, and a matting agent.

[0053] As the porous membrane of synthetic resin, it is preferable to be the porous membrane that is made by solidifying the synthetic resin solution that comprises synthetic resin and water-soluble polar organic solvent in water.As the method for producing this porous membrane, for example, take the above-mentioned polyurethane resin as an example, the polyurethane resin solution that comprises polyurethane resin, inorganic fine particles and polar organic solvent is coated on one side of suitable release substrate, then the coated polyurethane resin solution is immersed in water to solidify polyurethane resin.

[0054] Here, the polyurethane resin solution can contain inorganic fine particles with hydrophobic surfaces. Because the 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, in 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 allows for efficient formation of a porous membrane made of polyurethane resin.

[0055] Examples of the 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.

[0056] These inorganic fine particles may be either porous or non-porous. The shape of the inorganic fine particles 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 fine particles may be used alone or in combination of two or more. Among these, calcium carbonate fine particles or silicon dioxide fine particles are preferred because they have a high adsorption capacity for polar organic solvents such as N,N-dimethylformamide and are easy to form micropores.

[0057] The content of the inorganic fine particles varies depending on the type and cannot be generalized, but is usually preferably 1 to 75 mass% based on the total solid content of the polyurethane resin solution. A content of 1 mass% or more ensures sufficient porosity. A content of 75 mass% or less ensures that the strength, particularly the tensile strength, of the resulting microporous film is maintained and sufficient waterproofing is achieved. The content of the inorganic fine particles is preferably 3 to 40 mass% based on the total solid content of the polyurethane resin solution.

[0058] Examples of the polar organic solvent include N,N-dimethylformamide and N,N-dimethylacetamide.

[0059] A waterproof sound-permeable membrane according to a preferred embodiment can be produced, for example, by applying a polyurethane resin solution containing a synthetic resin mainly composed of polyurethane resin, inorganic fine particles in an amount of 1 to 75 mass% relative to the total solid content, and a polar organic solvent to a releasable substrate.

[0060] Examples of methods for applying the polyurethane resin solution to the releasable substrate include methods using a floating knife coater, a roll-on knife coater, a comma coater, a reverse coater, a lip coater, a roll coater, and a die coater.

[0061] The amount of polyurethane resin solution applied is 10 to 200 g / m2 in terms of solid content. 2 It is preferable that the density is 10 to 750 g / m 2 By setting the coating amount within this range, a porous membrane having a thickness of 10 to 150 μm can be obtained. That is, the waterproof sound-permeable membrane of the present invention preferably has a thickness of 10 to 150 μm, and more preferably 15 to 80 μm.

[0062] Following the step of applying the polyurethane resin solution to the releasable substrate, the polyurethane resin solution is immersed in water at 10 to 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.

[0063] The immersion time in water is preferably 30 seconds to 10 minutes, and more preferably 1 to 5 minutes. If the immersion time is less than 30 seconds, the polyurethane resin may not solidify completely, resulting in insufficient pore formation and insufficient waterproofing or sound permeability. If the immersion time exceeds 10 minutes, productivity decreases.

[0064] Next, the film is washed in warm water at 30 to 80°C for 3 to 15 minutes to remove any remaining polar organic solvent, and then dried by heat treatment at 50 to 150°C for 1 to 10 minutes. Thereafter, the releasable substrate is removed to form a porous film made of polyurethane resin.

[0065] The above-mentioned method for producing a porous polyurethane resin membrane can also be applied to synthetic resins other than polyurethane resin. In the present invention, polyurethane resin is suitable because of its flexibility and ease of forming a porous structure, but porous membranes can also be produced and used with other synthetic resins by the same method.

[0066] 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 the water-repellent treatment include paraffin-based water-repellent agents, silicone-based water-repellent agents, and fluorine-based water-repellent agents. Among these, fluorine-based water-repellent agents are preferred because they can impart high water repellency. The water-repellent treatment can be performed by conventional methods such as padding or spraying.

[0067] The waterproof sound-transmitting membrane used in the present invention may be a synthetic resin porous membrane such as the above-mentioned polyurethane resin porous membrane, or may be a rubber-like elastic body (thermosetting elastomer (rubber-based)). The rubber-like elastic body is not particularly limited as long as it is a material having rubber-like elasticity, and examples include silicone rubber, ethylene-propylene-diene rubber (EPDM), acrylic rubber, and natural rubber. Of these, silicone rubber is preferably used because of its excellent properties such as heat resistance and chemical resistance.

[0068] (3) Film 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 usable in small electrical appliances with significant built-in space restrictions, while if it is too thin, the strength will be reduced and it may become more susceptible to breakage.

[0069] 2.Support layer (1) Composition of the support base In addition to its waterproofing function, the support layer supports and fixes the waterproof sound-transmitting material to the housing and improves the handleability of the waterproof sound-transmitting material.The support layer also absorbs the compressive pressure when it is installed in the housing, and reinforces and stabilizes the shape of the membrane.

[0070] The support layer is laminated on at least one surface of the waterproof sound-permeable membrane, and may be laminated on only one surface or on both surfaces. Furthermore, the support layer is laminated on part of the waterproof sound-permeable membrane surface, not the entire membrane surface.

[0071] Preferably, the support layers are laminated on both sides of the waterproof sound-transmitting membrane. If the support layers are 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 that defects will occur due to scratches or deformation.

[0072] In order to reduce the stress required to compress the waterproof sound-transmitting member 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 a part of the support layer.

[0073] The layer constituting the support layer may be a single layer or multiple layers may be laminated, but it is preferable that at least a portion (or the entire layer) of the layers constituting the support layer includes a layer using a sheet for which the stress required for 40% compression in the vertical direction is 600 kPa or less, and it is more preferable that the layer includes a layer using a sheet for which the stress required for 40% compression in the vertical direction is 300 kPa or less.

[0074] By including a layer using such a sheet with low compressive stress as the support layer and combining it with a waterproof sound-transmitting 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 support layer is incorporated into equipment. Note that the "vertical direction" in the layers that make up the support layer refers to the thickness direction of the layer or the direction perpendicular to the membrane surface of the waterproof sound-transmitting membrane when laminated with the waterproof sound-transmitting membrane.

[0075] When the support layer is a single layer, the layer is preferably a layer using a sheet that requires a stress of 600 kPa or less to compress it by 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 by 40% in the vertical direction.

[0076] When the support layer is made up 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.

[0077] When the support layer is made up of multiple layers, there are no particular restrictions on the layer configuration, but multiple layers made of sheets with different resin types or sheets with different compressive stresses within the above range may be laminated as layers made of sheets with a stress of 600 kPa or less required to compress 40% in the vertical direction (hereinafter referred to as ``sheets with a compressive stress of 600 kPa or less'').

[0078] In addition, a layer using a hard sheet that requires a stress of more than 600 kPa to compress it by 40% in the vertical direction (a layer that hardly deforms when compressed during use) can also be provided as a spacer layer.

[0079] (2) Layers using sheets with a compressive stress of 600 kPa or less The sheet having a compressive stress of 600 kPa or less is preferably made of a synthetic resin material, such as polyolefin resin, polyurethane resin, polyacrylic resin, or polyester resin.

[0080] Examples of polyolefin resins include polyethylene, polypropylene, polyvinyl acetate, etc. Examples of polyurethane resins include polyester polyurethane, polyether polyurethane, polycarbonate polyurethane, etc.

[0081] Examples of polyacrylic resins include polyacrylic esters, polymethacrylic esters, etc. Examples of polyester resins include polyethylene terephthalate (PET), polybutylene terephthalate, etc.

[0082] Other examples include polyvinyl chloride, acrylic rubber, silicone rubber, etc. Preferably, a synthetic resin selected from the group consisting of polyolefin resins, polyacrylic resins, and polyurethane resins is used.

[0083] The synthetic resin material may be porous or non-porous, but in order to keep the stress required for 40% compression in the vertical direction at 600 kPa or less, it is preferable to use a sheet mainly made of a sheet layer (layers constituting the sheet) made of a porous synthetic resin material. Examples of synthetic resin porous materials include polyolefin-based porous materials such as polyethylene and polypropylene, polyurethane-based porous materials, and acrylic resin-based porous materials.

[0084] The sheet mainly made of a sheet layer made of a synthetic resin porous material may be one made only of a sheet layer made of a synthetic resin porous material, or one made mainly of a synthetic resin porous material and including other sheet layers. Examples of sheet layers made of materials other than a synthetic resin porous material include sheet layers (auxiliary layers) made of non-porous synthetic resin materials such as non-porous polyester resin materials.

[0085] The thickness of the auxiliary layer is not particularly limited, 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 a 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.

[0086] A sheet having a compressive stress of 600 kPa or less may have a pressure-sensitive adhesive layer on at least one side thereof. The pressure-sensitive adhesive layer may be provided on only one side or both sides of the sheet. The pressure-sensitive adhesive layer can be formed, for example, by applying a pressure-sensitive adhesive. Examples of pressure-sensitive adhesives include acrylic pressure-sensitive adhesives, silicone pressure-sensitive adhesives, and rubber pressure-sensitive adhesives.

[0087] The thickness of the adhesive layer is not particularly limited, but it is preferable that the stress required to compress the entire sheet by 40% in the vertical direction be 600 kPa or less, and therefore the thickness of the sheet layer made of a synthetic resin porous material is preferably 50% or more, more preferably 70% or more, and particularly preferably 80% or more of the thickness of the entire sheet.

[0088] Even when both the auxiliary layer and the 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 a 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.

[0089] A preferred example of a layer (waterproof adhesive layer) using a sheet having 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 has waterproof and adhesive functions at the interface between the waterproof sound-permeable membrane and the support layer, the interface between layers using each sheet in the support layer, and the interface between the support layer and the housing, etc.

[0090] 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 with 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.

[0091] The thickness of the sheet having 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. The upper limit of the thickness is also not particularly limited, but 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.

[0092] The physical properties of a sheet with a compressive stress of 600 kPa or less are generally independent of the type of resin, but when the sheet with a compressive stress of 600 kPa or less is mainly 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.

[0093] When the sheet having a compressive stress of 600 kPa or less is mainly composed of a sheet layer made of a polyurethane-based resin porous material or a polyacrylic-based resin porous material, the stress required for 40% compression in the vertical direction is more preferably 0.1 to 100 kPa, even more preferably 0.1 to 30 kPa, and particularly preferably 0.1 to 10 kPa. When constructing the support layer, it is preferable to combine layers of various resin types as needed.

[0094] More specifically, the sheet having a compressive stress of 600 kPa or less may be a sheet mainly made of a sheet layer made of a porous polyolefin resin material with pressure-sensitive adhesive layers on both sides, or a sheet mainly made of a porous polyurethane resin material or a porous polyacrylic resin material with a non-porous PET layer as an auxiliary layer.

[0095] (3) Spacer layer A layer using a hard sheet exhibiting high compressive stress can be provided as a spacer layer in part of the support layer. The spacer layer is preferably made of a non-porous synthetic resin, specifically a polyester film such as non-porous polyethylene terephthalate (PET).

[0096] The spacer layer is expected to adjust the total thickness of the waterproof sound-transmitting component and stabilize the structure by supporting it (maintaining the thickness without deformation when the waterproof sound-transmitting component is compressed and used). The spacer layer may or may not have an adhesive layer. For example, an adhesive waterproof tape with an adhesive applied to one or both sides, or a PET film without an adhesive applied can be used.

[0097] 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. It is certain that the stress required to compress it by 40% in the vertical direction is in the range exceeding 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.

[0098] The thickness of one 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.

[0099] (4) Structure of the support layer (i) Layer composition 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.

[0100] Preferably, the support layers are laminated on both sides of the waterproof sound-transmitting membrane. If the support layers are 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 assembled into the housing, making it less likely that defects will occur due to scratches or deformation.

[0101] 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.

[0102] When the waterproof sound-permeable membrane has support layers on both sides, one side may be a single layer and the other side may be multiple layers. Also, the support layers on both sides may be multiple layers.

[0103] When the support layer is a single layer, it is preferable that the support layer is made of a layer using a sheet with a compressive stress of 600 kPa or less and is laminated on the waterproof sound-permeable membrane. When the support layer is made of multiple layers, it is preferable that at least one layer is 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.

[0104] The 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 it is 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.

[0105] 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 having a compressive stress of 600 kPa or less. As the layer using a sheet having a compressive stress of 600 kPa or less, a sheet mainly containing a sheet layer made of the above-mentioned synthetic resin porous material can be preferably used.

[0106] More specifically, a sheet having a compressive stress of 600 kPa or less may be, for example, a sheet mainly made of a sheet layer of a porous polyolefin resin material and preferably having a compressive stress of about 50 to 300 kPa, or a sheet mainly made of a porous polyurethane resin material or a porous polyacrylic resin material and preferably having a compressive stress of about 0.1 to 100 kPa. Alternatively, a waterproof adhesive layer having an adhesive layer and / or a cushion layer not having an adhesive layer may be used.

[0107] By combining layers with and without these adhesive layers, or various layers with different compressive stresses, or by further 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-transmitting membrane, it is possible to obtain a waterproof sound-transmitting component in which the stress required to compress the waterproof sound-transmitting membrane by 40% in the direction perpendicular to the membrane surface is 1 to 600 kPa.

[0108] The waterproof sound-transmitting member of the present invention can be produced by laminating the sheets, films, membranes, etc. that constitute each layer into the desired shape based on the above design. Examples of lamination methods include methods in which the layers are bonded together by known means such as pressure bonding.

[0109] 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.

[0110] More specifically, a support layer including a layer (preferably a waterproof adhesive layer or cushion layer) using 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 a nonporous synthetic resin such as nonporous PET, or a nonporous synthetic resin film such as a nonporous PET film) may be laminated on the support layer as needed.

[0111] If a spacer layer is formed between the waterproof sound-transmitting membrane and a layer using a sheet contained in the support layer with a compressive stress of 600 kPa or less, the layer structure of the entire waterproof sound-transmitting member will be stabilized. Also, spacer layers can be provided on both sides of the layer using a sheet contained in the support layer with a compressive stress of 600 kPa or less to sandwich them together, which will further stabilize the layer structure of the entire waterproof sound-transmitting member.

[0112] 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. A waterproof adhesive layer or cushion layer is then laminated on top of that, and a spacer layer is then laminated on top of that.

[0113] The thickness of the support layer (the thickness of the layer in the case of a single layer, or the total thickness of the constituent layers in the case of a multi-layer structure) is not particularly limited, but is preferably 30 to 3000 μm, more preferably 100 to 1500 μm, even more preferably 300 to 1000 μm, and particularly preferably 500 to 800 μm.

[0114] The thickness of one layer using a sheet having a compressive stress of 600 kPa or less is preferably 30 to 3000 μm, more preferably 100 to 1500 μm, the same as in the case of a single layer.

[0115] 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.

[0116] When layers using sheets with a compressive stress of 600 kPa or less are provided on both sides of a waterproof sound-transmitting membrane, it is desirable that the total thickness of the layers using sheets with a compressive stress of 600 kPa or less is preferably 60% or more, more preferably 70 to 98%, even more preferably 85 to 98%, and particularly preferably 90 to 96% of the total thickness of the waterproof sound-transmitting member.

[0117] 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.

[0118] (ii) Shape of the support layer When supporting layers are laminated on both sides of a waterproof sound-permeable membrane, it is preferable that the supporting layers on both sides be in overlapping positions with the same shape 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.

[0119] It is preferable that the support layer be laminated around the periphery of the waterproof sound-permeable membrane so as not to interfere with the vibration of the waterproof sound-permeable membrane. Also, it is preferable that the shape of the support layer has 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.

[0120] To make it difficult for the stress applied by compression of the waterproof sound-permeable material to be biased, and to reduce distortion in the sound-permeable area of ​​the waterproof sound-permeable membrane and reduce acoustic loss, the area of ​​the support layer (cross section parallel to the membrane surface) laminated on the waterproof sound-permeable membrane should be 1 mm 2 It is preferable to set it to 5mm or more. 2 It is more preferable to set it to more than this.

[0121] On the other hand, in order to contribute to the miniaturization of electrical products by saving space and to reduce the load on the housing by reducing the force required for compression, the area of ​​the support layer laminated on the waterproof sound-permeable membrane must be 50 mm 2 It is preferable to keep it below 30 mm 2 It is more preferable to do the following:

[0122] 3. Sound transmission 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.

[0123] The wider the sound-permeable area, the smaller the acoustic loss, so the area of ​​the sound-permeable area is 0.5 mm 2 It is preferable that it is 1.5 mm or more. 2 On the other hand, the smaller the area, the more stable the shape and the less likely it is to be distorted, and the smaller the acoustic loss during compression. 2Less than 20mm is preferable 2 The following is more preferred:

[0124] The planar shape of the sound-permeable region is preferably circular or a similar shape, as it is stable and less likely to distort, and therefore the circularity calculated by formula (1) is preferably 0.45 to 1, and more preferably 0.6 to 1. It is also preferable that the sound-permeable region has no corners.

[0125] (Number 1) Circularity = 4 x Pi x Area ÷ [Perimeter] 2 Formula (1)

[0126] An example of the configuration of the waterproof sound-transmitting member of the present invention is shown in Figure 2. 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 a waterproof sound-transmitting membrane 2 so as to be formed around the periphery of a sound-transmitting region 4. [Example]

[0127] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to the following examples. Note that the measurement and evaluation of physical properties in the following examples and comparative examples were carried out according to the following methods.

[0128] (1) Acoustic loss The acoustic loss measurement will be explained using Figure 3. Inside an anechoic box 16, a speaker 11 was used to emit a TSP signal with a sound pressure of 94 dB, including a frequency of 1 kHz. The output of a MEMS (ADMP401) analog microphone 12 built into a microphone fixture 13 was converted to digital form by an analyzer and analyzed using analysis software (CLIO Pocket, manufactured by Audiomatica), measuring the sound pressure level at a frequency of 1 kHz.

[0129] 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 portion with a predetermined 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.

[0130] The speaker 11, the opening 14, the waterproof sound-transmitting member 1, and the 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 a circle with a diameter of 1 mm, the distance from the waterproof sound-transmitting member 1 to the MEMS analog microphone 12 in the internal space 15 is 6 mm, and the volume of the internal space is 27 mm. 3 is.

[0131] The microphone jig 13 was placed 4.5 cm from the speaker 11 so that the plane on which the opening 14 was provided was parallel to the sound-generating part of the speaker (so that sound was incident perpendicularly).

[0132] The difference between the sound pressure level measured using only the microphone jig and the sound pressure level measured with the waterproof sound-transmitting material attached to the opening of the microphone jig was calculated as the acoustic loss. The lower the acoustic loss, the higher the sound permeability.

[0133] The gap between the waterproof sound-transmitting material mounting points was adjusted appropriately, and the acoustic loss of the waterproof sound-transmitting material was measured at a compression rate of 0% and at 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.

[0134] (2) Tensile test A test piece measuring 50 mm in width and 80 mm in length was attached to a tensile tester (product name "Autograph AG-IS type", manufactured by Shimadzu Corporation) with a gripping distance of 50 mm, and a tensile test was carried out 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 calculated based on the cross-sectional area (mm 2 The tensile modulus (MPa) was calculated by dividing the measured value by the square root of the square root of the specimen. The above measurement was carried out 5 times each with the specimen rotated 90° in the vertical and horizontal directions, for a total of 10 times, and the average value was calculated.

[0135] (3) Water pressure resistance Measurements were made in accordance with JIS L 1092B method (high water pressure method). However, because the waterproof sound-permeable member did not have a sufficient measurement area, the waterproof sound-permeable member was attached to a stainless steel plate with a circular hole, and water leakage was determined at a single point. When measuring the waterproof sound-permeable 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 water pressure. 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.

[0136] (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, and the thickness of the waterproof sound-permeable member was measured.

[0137] (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 placed as shown in Figure 4, and a load was applied by moving the parallel plate 17 in the compression direction 18 (perpendicular to the surface of the waterproof sound-transmitting membrane). The force required to compress 40% of the maximum thickness of the waterproof sound-transmitting member (total thickness 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 (area overlapping in the vertical direction). The measurement area was 2 cm 2 The compression speed was 0.01 mm / min. Measurements were taken for five samples and the average value was calculated.

[0138] The individual compressive stresses of the cushioning material, double-sided adhesive waterproof tape, and non-porous PET film used in the support layer were each measured separately in advance at 2.5mm x 2.5mm = 6.25mm. 2 Measurements were performed on five samples for each measurement, and the average value was calculated.

[0139] In addition, for non-porous PET and those using only non-porous PET as the core material, it is difficult to compress them to 40%. Therefore, the sample size was set to 6.25 mm. 2 It was difficult to obtain values ​​above 1569 kPa, the upper limit of measurement.

[0140] [Example 1] A polyurethane resin solution having the following formulation was prepared. <Prescription> MP865PS; 100 parts by mass (DIC, polyurethane resin, solid content 30% by mass, 100% modulus 11 MPa) Leatheroid LU2850M; 65 parts by weight (Dainichiseika Color & Chemicals Mfg. Co., Ltd., silica fine particle dispersion, solid content 20% by mass) Dilac Black L1584: 4 parts by weight (DIC Corporation, black pigment, solid content 25% by mass) N,N-dimethylformamide: 28 parts by mass

[0141] Next, the polyurethane resin solution was applied to a release substrate using a knife-on-roll coater to a coating thickness such that the resulting waterproof sound-transmitting membrane would have a thickness of 30 μm. It was then immersed in 20°C water for 1.5 minutes to allow 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 find that it was 3.9 MPa, the water pressure resistance was 70 kPa, and the air permeability was 19 seconds / 100 mL.

[0142] 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 also 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.

[0143] 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).

[0144] The waterproof sound-transmitting material 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 thickness of the waterproof sound-transmitting material was 680 μm. The sound-transmitting area had an area of ​​2.64 mm 2 , circularity 0.9, and the area of ​​the support layer is 12.3 mm 2 It was.

[0145] 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-permeable material, and double-sided adhesive waterproof tape 2 accounted for 58.8% of the total thickness of the waterproof sound-permeable material, for a total of 95.6%.

[0146] Table 1 shows the results of measurements of the acoustic loss, water pressure resistance, and stress required for 40% compression of the waterproof sound-transmitting material at compression rates of 0% and 40%. By using a waterproof sound-transmitting material that requires a small stress to be compressed by 40%, acoustic loss was unlikely to increase even when a waterproof sound-transmitting membrane with a low tensile modulus was used and compressed by 40%.

[0147] [Example 2] 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 double-sided adhesive waterproof tape 3 (manufactured by Nitto Denko Corporation, product name "No. 5601"; non-porous PET; thickness 10 μm), and a cushion material 1 (manufactured by Inoac Corporation, product name "PORON SR-S15P"; porous polyurethane resin + PET; thickness 500 μm). Except for this, the 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.

[0148] The stress required to compress the double-sided adhesive waterproof tape 1 by 40% is 111 kPa, and the stress required to compress the cushioning material 1 by 40% is 0.2 kPa. Note that the double-sided adhesive waterproof tape 3 has a core material of non-porous PET, which makes it difficult to compress it by 40%. Therefore, the stress required to compress the double-sided adhesive waterproof tape 3 by 40% is at least 111 kPa for a sample size of 6.25 mm. 2 It is clear that the pressure is above the upper limit of measurement, 1569 kPa.

[0149] The double-sided adhesive waterproof tape 1 accounted for 31.2% of the total thickness of the waterproof sound-transmitting member, and the cushioning material 1 accounted for 62.5% of the total thickness of the waterproof sound-transmitting member, for a total of 93.7%.

[0150] Table 1 shows the results of measurements of the acoustic loss, water pressure resistance, and stress required for 40% compression of the waterproof sound-transmitting material at compression rates of 0% and 40%. By using a waterproof sound-transmitting material that requires a small stress to be compressed by 40%, acoustic loss was unlikely to increase even when a waterproof sound-transmitting membrane with a low tensile modulus was used and compressed by 40%.

[0151] [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 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). Except for this, the waterproof sound-transmitting member was produced in the same manner as in Example 1, with 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 laminated in this order. The thickness of the waterproof sound-transmitting member was 700 μm.

[0152] 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 material, and cushion material 2 accounted for 57.1% of the total thickness of the waterproof sound-transmitting material, for a total of 92.8%.

[0153] Table 1 shows the results of measurements of the acoustic loss, water pressure resistance, and stress required for 40% compression of the waterproof sound-transmitting material at compression rates of 0% and 40%. By using a waterproof sound-transmitting material that requires a small stress to be compressed by 40%, acoustic loss was unlikely to increase even when a waterproof sound-transmitting membrane with a low tensile modulus was used and compressed by 40%.

[0154] [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 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). Except for 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 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 700 μm.

[0155] The stress required to compress double-sided adhesive waterproof tape 1 by 40% was 111 kPa, and the stress required to compress cushion material 3 by 40% was 2 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 material, and cushion material 3 accounted for 57.1% of the total thickness of the waterproof sound-transmitting material, for a total of 92.8%.

[0156] Table 1 shows the results of measurements of the acoustic loss, water pressure resistance, and stress required for 40% compression of the waterproof sound-transmitting material at compression rates of 0% and 40%. By using a waterproof sound-transmitting material that requires a small stress to be compressed by 40%, acoustic loss was unlikely to increase even when a waterproof sound-transmitting membrane with a low tensile modulus was used and compressed by 40%.

[0157] [Example 5] The waterproof sound-transmitting membrane was made into a circle with a diameter of 4 mm, the support layer was made into a circle with a diameter of 4 mm, and a circular opening with a diameter of 2.2 mm was formed in the center of the support layer. The support layer was then laminated with 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. The waterproof sound-transmitting member was produced in the same manner as in Example 1, 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 2 were laminated in this order. The thickness of the waterproof sound-transmitting member was 730 μm. The sound-transmitting area had an area of ​​3.8 mm. 2 , circularity 1, and the area of ​​the support layer is 8.8 mm 2 It was.

[0158] 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.

[0159] Table 1 shows the results of measurements of the acoustic loss, water pressure resistance, and stress required for 40% compression of the waterproof sound-transmitting material at compression rates of 0% and 40%. By using a waterproof sound-transmitting material that requires a small stress to be compressed by 40%, acoustic loss was unlikely to increase even when a waterproof sound-transmitting membrane with a low tensile modulus was used and compressed by 40%.

[0160] [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 in the center. The thickness of the waterproof sound-transmitting member was 730 μm. The sound-transmitting region had an area of ​​3.8 mm 2 , circularity 1, and the area of ​​the support layer is 24.5 mm 2 It was.

[0161] 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-transmitting material.

[0162] Table 1 shows the results of measurements of the acoustic loss, water pressure resistance, and stress required for 40% compression of the waterproof sound-transmitting material at compression rates of 0% and 40%. By using a waterproof sound-transmitting material that requires a small stress to be compressed by 40%, acoustic loss was unlikely to increase even when a waterproof sound-transmitting membrane with a low tensile modulus was used and compressed by 40%.

[0163] [Example 7] The support layer was made of a double-sided adhesive waterproof tape 4 (manufactured by Nitto Denko Corporation, product name "No. 5615"; thickness 150 μm), two layers of double-sided adhesive waterproof tape 5 (manufactured by Nitto Denko Corporation, product name "No. 5605"; thickness 50 μm), a cushion material 4 (manufactured by Inoac Corporation, product name "PORON SR-S20P"; porous polyurethane + PET; thickness 400 μm), and a 50 μm thick PET film. The 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.

[0164] 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 material.

[0165] Table 1 shows the results of measurements of the acoustic loss, water pressure resistance, and stress required for 40% compression of the waterproof sound-transmitting material at compression rates of 0% and 40%. By using a waterproof sound-transmitting material that requires a small stress to be compressed by 40%, acoustic loss was unlikely to increase even when a waterproof sound-transmitting membrane with a low tensile modulus was used and compressed by 40%.

[0166] [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 in the center. The thickness of the waterproof sound-transmitting member was 730 μm. The sound-transmitting region had an area of ​​3.8 mm 2 , circularity 1, and the area of ​​the support layer is 24.5 mm 2 It was.

[0167] 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 material.

[0168] Table 1 shows the results of measurements of the acoustic loss, water pressure resistance, and stress required for 40% compression of the waterproof sound-transmitting material at compression rates of 0% and 40%. By using a waterproof sound-transmitting material that requires a small stress to be compressed by 40%, acoustic loss was unlikely to increase even when a waterproof sound-transmitting membrane with a low tensile modulus was used and compressed by 40%.

[0169] [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 for the support layer, and the waterproof sound-transmitting member was laminated in this order. The waterproof sound-transmitting member had a thickness of 580 μm.

[0170] 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-permeable material, and double-sided adhesive waterproof tape 1 accounted for 43.1% of the total thickness of the waterproof sound-permeable material, for a total of 94.8%.

[0171] Table 1 shows the results of measurements of the acoustic loss, water pressure resistance, and stress required for 40% compression of the waterproof sound-transmitting material at compression rates of 0% and 40%. By using a waterproof sound-transmitting material that requires a small stress to be compressed by 40%, acoustic loss was unlikely to increase even when a waterproof sound-transmitting membrane with a low tensile modulus was used and compressed by 40%.

[0172] [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.

[0173] Table 1 shows the results of measurements of the acoustic loss, water pressure resistance, and stress required for 40% compression of the waterproof sound-transmitting material at compression rates of 0% and 40%. Because the stress required for 40% compression is large, when a waterproof sound-permeable membrane with a low tensile modulus is used and compressed to 40%, the acoustic loss increases, making it unsuitable for use in compression.

[0174] 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.

[0175] Table 1 shows the results of measurements of the acoustic loss, water pressure resistance, and stress required for 40% compression of the waterproof sound-transmitting material at compression rates of 0% and 40%. Because the stress required for 40% compression is large, when a waterproof sound-permeable membrane with a low tensile modulus is used and compressed to 40%, the acoustic loss increases, making it unsuitable for use in compression.

[0176] 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)

[0177] Double-sided adhesive waterproof tape 3; Nitto Denko Corporation, product name "No. 5601" (non-porous PET film: thickness 10 μm) Double-sided adhesive waterproof tape 4; Nitto Denko Corporation, product name "No. 5615" (non-porous PET film: thickness 150 μm)

[0178] Double-sided adhesive waterproof tape 5; Nitto Denko Corporation, product name "No. 5605" (non-porous PET film: thickness 50 μm) Double-sided adhesive waterproof tape 6: Sekisui Chemical Co., Ltd., product name "5230VSB" (porous polyethylene, thickness 300 μm)

[0179] 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)

[0180] Cushioning material 1: Inoac Corporation, product name "PORON SR-S15P" (porous polyurethane resin 450 μm + non-porous PET 50 μm: total thickness 500 μm) Cushioning material 2: Inoac Corporation, product name "PORON SR-S40P (porous polyurethane resin 350 μm + non-porous PET 50 μm: total thickness 400 μm)

[0181] Cushioning material 3: Iwatani Corporation, product name "ISR-ACF-TH" (porous acrylic resin; thickness 400 μm) Cushioning material 4: Inoac Corporation, product name "PORON SR-S20P" (porous polyurethane resin 350 μm + non-porous PET 50 μm: total thickness 400 μm)

[0182] The double-sided adhesive waterproof tapes 1, 2, and 6 and the cushioning materials 1, 2, 3, and 4 correspond to the "sheet having a stress of 600 kPa or less required for 40% compression in the vertical direction" of the present invention. The double-sided adhesive waterproof tapes 3, 4, and 5 correspond to the spacer layer.

[0183] [Table 1] [Industrial Applicability]

[0184] The waterproof sound-transmitting member of the present invention has high waterproof properties, and even when used in a compressed state to prevent sound interference within a 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 suitably used for waterproof protection of microphones and speakers in electrical products. [Explanation of symbols]

[0185] 1: Waterproof sound-transmitting material 2: Waterproof sound-permeable membrane 3: Support layer 4: Sound transmission area 11: Speaker 12: MEMS analog microphone 13: Microphone fixture 14: Opening 15: Interior space 16:Anechoic box 17: Parallel plates 18: Compression direction

Claims

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 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.

2. 2. The waterproof sound-transmitting member according to claim 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. 3. The waterproof sound-transmitting member according to claim 2, wherein the sheet for which a stress of 600 kPa or less is required for 40% compression in the vertical direction includes a sheet layer made of a synthetic resin porous material.

4. 4. The waterproof sound-transmitting member according to claim 3, wherein the synthetic resin porous material is a porous synthetic resin 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 total thickness of the waterproof sound-transmitting member. The waterproof sound-transmitting member according to any one of claims 2 to 4.

6. 2. The waterproof sound-transmitting member according to claim 1, wherein the waterproof sound-transmitting membrane has a tensile modulus of elasticity of 0.5 to 20 MPa.

7. 2. The waterproof sound-transmitting member according to claim 1, wherein 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 claim 1, wherein the waterproof sound-transmitting membrane has an air permeability of 3 to 500 seconds / 100 mL according to JIS L 1096 Gurley method.

9. The waterproof sound-transmitting member according to claim 1, wherein the waterproof sound-transmitting membrane has a thickness of 15 to 80 μm.

10. 2. The waterproof sound-transmitting member according to claim 1, wherein the waterproof sound-transmitting membrane is made of a polyurethane resin.

11. The area of ​​the support layer laminated on at least one side of the waterproof sound-permeable membrane is 1 to 50 mm ２ The waterproofing method according to claim 1, Sound-permeable material.

12. 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 a circularity of 0.45 to 1 b) Area is 0.5 to 40 mm ２ Being

13. 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 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.

Images