Sound absorbing material and vehicle component

Abstract

A sound-absorbing material sequentially provided with a protective layer, a first base material layer having communication holes, and a second base material layer having communication holes, the soft tenacity value of the protective layer represented by the following formula (I) being 1 to 75 [MPa / µm]. Soft tenacity value = (tensile elastic modulus of the protective layer at 25°C [MPa] x Shore A hardness of the protective layer) / protective layer thickness [µm] ··· (I).

Description

Technical Field

[0001] This invention relates to a sound-absorbing material and a vehicle component. Background Technology

[0002] As a sound-absorbing material with excellent sound absorption properties in the low-frequency region, sound-absorbing materials formed by stacking two layers of non-woven fabric are known (for example, Patent Document 1).

[0003] Previous technical documents

[0004] Patent documents

[0005] Patent Document 1: International Publication No. 2020 / 213685 Summary of the Invention

[0006] The technical problem to be solved by the invention

[0007] When the sound-absorbing material is made of nonwoven fabric, there is room for improvement, especially in terms of durability against external mechanical impacts.

[0008] The present invention was made in view of the above circumstances, and its object is to provide a sound-absorbing material with excellent sound absorption characteristics and durability in the low-frequency region. A further object of the present invention is to provide a vehicle component incorporating the sound-absorbing material.

[0009] means for solving technical problems

[0010] One aspect of the present invention relates to a sound-absorbing material comprising, in sequence: a protective layer, a first substrate layer having a communicating hole, and a second substrate layer having a communicating hole, wherein the protective layer has a softness and toughness value of 1 to 75 [MPa / μm] as expressed by the following formula (I).

[0011] Softness and toughness value = (tensile elastic modulus of the protective layer at 25℃ [MPa] × Shore A hardness of the protective layer) / thickness of the protective layer [μm] ···(I)

[0012] In one embodiment, the protective layer may be a layer containing an elastomer.

[0013] In one embodiment, the protective layer may be a non-woven fabric.

[0014] In one embodiment, the sound-absorbing material may further have a resin layer between the protective layer and the first substrate layer.

[0015] In one embodiment, the resin layer may comprise polyolefin, polyester, or polyamide.

[0016] In one embodiment, the sound-absorbing material may further have a metal vapor-deposited layer on at least one surface of the resin layer.

[0017] In one embodiment, the first substrate layer and the second substrate layer can be resin foam or nonwoven fabric.

[0018] In one embodiment, the thickness of the first substrate layer may be thinner than the thickness of the second substrate layer.

[0019] In one embodiment, the thickness of the sound-absorbing material can be 1 to 100 mm.

[0020] One aspect of the present invention relates to a vehicle component having the aforementioned sound-absorbing material.

[0021] Invention Effects

[0022] According to the present invention, a sound-absorbing material with excellent sound absorption characteristics and durability in the low-frequency region can be provided. Furthermore, according to the present invention, a vehicle component incorporating the sound-absorbing material can be provided. Attached Figure Description

[0023] Figure 1 This is a schematic cross-sectional view of a sound-absorbing material according to one embodiment.

[0024] Figure 2 This is a schematic cross-sectional view of a sound-absorbing material according to one embodiment. Detailed Implementation

[0025] The following is for reference only, depending on the situation. Figure 1 The embodiments of the present invention will be described in detail below. Furthermore, in this specification, the numerical range indicated by "~" represents the range encompassed by the values ​​before and after "~" as the minimum and maximum values, respectively. Also, the upper or lower limit of the numerical range described in this specification can be replaced with the values ​​shown in the embodiments.

[0026] <Sound Absorbing Materials>

[0027] Figure 1 This is a schematic cross-sectional view of a sound-absorbing material according to one embodiment. The sound-absorbing material 10 sequentially includes a protective layer 1, a first substrate layer 2 having connecting holes as a substrate layer, and a second substrate layer 3 having connecting holes. Sound (sound energy) incident from the protective layer side dissipates as heat energy when penetrating the sound-absorbing material. Sound attenuation can thus be observed.

[0028] Figure 2 This is a schematic cross-sectional view of a sound-absorbing material according to one embodiment. The sound-absorbing material 20 sequentially includes a protective layer 1, a resin layer 4, a first substrate layer 2 having connecting holes as a substrate layer, and a second substrate layer 3 having connecting holes.

[0029] (Substrate layer)

[0030] Examples of substrate layers with interconnected pores include resin foam, nonwoven fabric, porous polymers, and porous ceramics. Among these, resin foam or nonwoven fabric is preferable for its superior sound absorption characteristics in the low-frequency region. The first and second substrate layers can be made of the same material or different materials.

[0031] Examples of materials that can be used for resin foaming include polyethylene resin, polypropylene resin, polyurethane resin, polyester resin, acrylic resin, polystyrene resin, melamine resin, silicone resin, natural rubber, and synthetic rubber. From the perspective of heat resistance and flame retardancy, melamine resin is a suitable material for resin foaming.

[0032] Examples of fibers used to construct nonwoven fabrics include organic and inorganic fibers. Examples of organic fibers include polyolefin fibers such as polyethylene (low-density or high-density), polypropylene (PP), copolymer polyethylene, and copolymer polypropylene; polyester fibers such as polyethylene terephthalate (PET), trimethyl terephthalate, polybutylene terephthalate, polyethylene naphthalate, and polybutylene naphthalate; polyamide fibers; acrylic fibers; nylon fibers; rayon fibers; and natural fibers such as wool. Examples of inorganic fibers include glass fibers, metal fibers, ceramic fibers, and carbon fibers. The fibers used to construct nonwoven fabrics may include one or more of these types.

[0033] From the viewpoint of excellent sound absorption characteristics in the low-frequency region, the thickness of the substrate layer can be set to 0.1–50 mm, 0.5–20 mm, or 2.0–10 mm. The first substrate layer and the second substrate layer can have the same thickness or different thicknesses. From the viewpoint of excellent sound absorption characteristics in the low-frequency region, the thickness of the first substrate layer (the substrate layer on the incident side of the sound) can be thinner than the thickness of the second substrate layer.

[0034] Considering the excellent sound absorption characteristics in the low-frequency region, the basis weight of the substrate layer can be set to 50–2000 g / m². 2 It can also be 100-1000 g / m 2 .

[0035] From the perspective of excellent sound absorption characteristics in the low-frequency region, sound-absorbing materials can further incorporate other substrate layers with interconnecting pores. In other words, in addition to the first substrate layer and the second substrate layer with interconnecting pores, the sound-absorbing material can further incorporate a third substrate layer and a fourth substrate layer with interconnecting pores, etc. Each substrate layer can be made of the same material or different materials.

[0036] (protective layer)

[0037] The flexibility and toughness value of the protective layer, expressed by the following formula (I), is 1–75 MPa / μm. From the viewpoint of achieving a higher level of both sound absorption properties and durability, the flexibility and toughness value can be 2–70 MPa / μm or 5–65 MPa / μm.

[0038] Softness and toughness value = (tensile elastic modulus of the protective layer at 25℃ [MPa] × Shore A hardness of the protective layer) / thickness of the protective layer [μm] ···(I)

[0039] The softness-toughness value refers to a characteristic value set with regard to the impact absorption performance and impact durability per unit thickness of the protective layer. The impact absorption performance per unit thickness can be evaluated by Shore A hardness, and the impact durability can be evaluated by tensile modulus of elasticity. If the product of the two is within the specified range, it indicates that the protective layer is appropriately soft and tough.

[0040] The tensile modulus of elasticity is determined using a tensile testing machine. Specifically, a 20mm × 50mm sample is prepared, and the maximum value of the modulus of elasticity at 25°C when the sample is stretched using a tensile testing machine at a tensile speed of 100mm / min is taken as the tensile modulus of elasticity. As long as the above formula is satisfied, there are no particular limitations. From a durability point of view, the tensile modulus of elasticity can be set to 1–2000MPa, or it can be set to 10–1000MPa.

[0041] Shore A hardness is determined using a type A hardness tester. Specifically, prepare a 20mm × 50mm sample, stack the samples to a thickness of at least 1mm, and let them stand at 25°C for 1 hour. The hardness value measured within 1 second after standing (or the value displayed immediately after measurement) is taken as the Shore A hardness. There are no particular limitations as long as the above formula is satisfied. From a durability point of view, the Shore A hardness can be set to 20–95, or even 30–92.

[0042] The thickness of the protective layer is measured using a thickness gauge. As long as the above formula is satisfied, there are no particular limitations. From a durability point of view, the thickness of the protective layer can be set to 10–2000 μm, or it can be 50–500 μm.

[0043] In order to set the softness and toughness values ​​within the range specified above, the properties can be adjusted according to the following points.

[0044] Methods for adjusting the elastic modulus and Shore A hardness include adjusting the density of the protective layer, imparting rigid components to the material, and increasing the proportion of inorganic components such as metals, ceramics, and silica in the material. The elastic modulus and Shore A hardness can also be adjusted by adjusting the amount of porosity in the protective layer. Furthermore, the elastic modulus and Shore A hardness can be adjusted by the composition of the skeleton forming the porous protective layer, the thickness of the skeleton, and the bonding method of the skeleton.

[0045] For example, either the elastic modulus or the Shore A hardness can be adjusted by appropriately combining the methods mentioned above. For example, the Shore A hardness can be reduced while maintaining the elastic modulus by thickening the skeleton constituting the protective layer while creating voids in the protective layer.

[0046] From the viewpoint of achieving both higher levels of sound absorption and durability, the protective layer can also be a layer containing an elastomer. Examples of elastomers that satisfy the aforementioned softness and toughness values ​​include thermoplastic elastomers and thermosetting elastomers. Examples of thermoplastic elastomers include resins such as polyolefins, polystyrene, polyurethanes, polyesters, polyethers, polyacrylic acids, polyamides, vinyl chloride, chlorinated polyethylene, polydienes, fluorinated resins, silicones, and polycarbonates, or modified resins thereof. Examples of thermosetting elastomers include resins such as fluorinated resins, silicones, polyurethanes, and epoxy resins, as well as synthetic rubbers or natural rubbers such as isoprene rubber, ethylene propylene rubber, ethylene propylene diene monomer (EPDM) rubber, and nitrile rubber (NBR), or modified resins thereof. From the viewpoints of lightweighting, thin-film properties, heat resistance, and durability, polyurethane or polyester resins are preferred.

[0047] In addition to the elastomer, the layer containing the elastomer can also contain other components. From the perspective of improving heat resistance, durability, sound absorption, vibration damping, and sound insulation, other components can include inorganic particles such as silica, alumina, and talc, metal particles, and organic resin particles. From a lightweighting perspective, hollow particles can be included. Furthermore, from a lightweighting perspective, the layer containing the elastomer can include foamed materials and foam-based bubble structures.

[0048] From the perspective of achieving both higher levels of sound absorption and durability, the protective layer can be a nonwoven fabric. As a nonwoven fabric that meets the aforementioned softness and strength requirements, from a durability standpoint, examples include nonwoven fabrics with firmly bonded fibers, such as nonwoven fabrics (PET nonwoven fabrics, etc.) manufactured using chemical bonding, thermal bonding, or needle punching methods.

[0049] From the perspective of achieving a higher level of both sound absorption and durability, the weight per unit area of ​​the protective layer can be set to 10–1000 g / m². 2 It can also be 50-800g / m2 .

[0050] From the perspective of achieving a higher level of both sound absorption and durability, the density of the protective layer can be set to 0.1–10.0 g / cm³. 3 It can also be 0.2–2.0 g / cm³. 3 .

[0051] When the protective layer is a nonwoven fabric, from the viewpoint of achieving both sound absorption properties and durability at a higher level, the average fiber diameter of the fibers constituting the nonwoven fabric can be set to 0.1 to 100 μm, or 1 to 50 μm.

[0052] The average fiber diameter can be determined by averaging the fiber diameters of each fiber as measured from photographs taken at 1000x magnification using an electron microscope. Specifically, the average fiber diameter can be determined by measuring the diameters of a total of 100 fibers randomly selected from 10 photographs, ranging from 0.1 μm in diameter, averaging them, and rounding to two decimal places.

[0053] (Resin layer)

[0054] From the perspectives of improving sound absorption characteristics, enhancing durability, and imparting functionality, sound-absorbing materials can further incorporate a resin layer between the protective layer and the substrate layer. Examples of resins used to constitute the resin layer include polyolefin resins such as polyethylene (low-density or high-density), polypropylene (extended or unextended), copolymer polyethylene, and copolymer polypropylene; polyester resins such as polyethylene terephthalate, trimethyl terephthalate, polybutylene terephthalate, polyethylene naphthalate, and polybutylene naphthalate; fluorinated resins such as PTFE, FEP, and PFA; polyimide resins, polyamide resins, aramid resins, vinyl chloride resins, acrylic resins, polycarbonate resins, polyphenylene sulfide resins, polyvinyl alcohol resins, polystyrene resins, polyacrylonitrile resins, and ethylene-vinyl acetate resins. The resin layer is a layer (film) without interconnected pores.

[0055] From the perspective of excellent sound absorption characteristics in the low-frequency region, the thickness of the resin layer can be set to 0.5-500μm, 5-250μm, or 10-100μm.

[0056] From the perspective of improving sound absorption by adjusting membrane properties and imparting infrared reflection, a metal vapor-deposited layer can be formed on the surface of the resin layer. That is, the sound-absorbing material can further have a metal vapor-deposited layer on the surface of the resin layer. The metal vapor-deposited layer can be formed by physical vapor deposition, such as vacuum vapor deposition, or chemical vapor deposition, using metals such as aluminum, copper, zinc, zinc alloys, and silver. The metal vapor-deposited layer can be formed on both sides of the resin layer or on one side of the resin layer.

[0057] From the viewpoint of improving sound absorption in the low-frequency region and adjusting the sound absorption frequency peak, the resin layer can be a porous membrane. The porous membrane can have pores arranged in a grid-like or rhomboid shape. From the viewpoint of excellent sound absorption characteristics in the low-frequency region, the pores can be circular with a diameter of 0.1–50.0 mm, 0.2–10.0 mm, or 0.3–5.0 mm. The shape of the pores can be circular, elliptical, rectangular, polygonal, etc.

[0058] (Adhesive layer)

[0059] An adhesive layer may be further provided between the aforementioned layers of the sound-absorbing material. The sound-absorbing material may have an adhesive layer between the protective layer and the first substrate layer, and between the first substrate layer and the second substrate layer, at least one of these conditions. Furthermore, the sound-absorbing material may have an adhesive layer between the protective layer and the resin layer, between the resin layer and the first substrate layer, and between the first substrate layer and the second substrate layer, at least one of these conditions.

[0060] Examples of adhesive layers include layers containing adhesive components such as vinyl acetate resin, polyolefin resin, ethylene-vinyl acetate copolymer resin, isobutylene-maleic anhydride copolymer resin, acrylic copolymer resin, acrylic monomers, acrylic oligomers, styrene-butadiene rubber, vinyl chloride resin, chloroprene rubber, nitrile rubber, polyurethane resin, silanized polyurethane resin, epoxy resin, modified epoxy resin, polyethylene resin, ionomer resin, silicone resin, modified silicone resin, water glass, and silicates; or laminates (e.g., double-sided tape) having layers containing these adhesive components on both sides of a support, wherein the support is composed of paper, cloth, resin film, metal strip, etc. Each adhesive layer can be made of the same material or different materials.

[0061] The thickness of the adhesive layer is not particularly limited and can be set from 0.01 to 500 μm, or from 1 to 250 μm. Each adhesive layer can have the same thickness or different thicknesses.

[0062] There is no particular limitation on the weight of the adhesive layer; it can be set from 1 to 500 g / m². 2 It can be 5-200g / m 2 It can also be 10-150g / m 2 Each adhesive layer can have the same thickness or different thicknesses.

[0063] Considering the manifestation of sound absorption characteristics, the workability of materials, and space saving, the thickness of sound-absorbing materials can be set to 1-100mm, 2-50mm, or 5-30mm.

[0064] Considering the excellent sound absorption characteristics in the low-frequency region, the average vertical incident sound absorption rate of the sound-absorbing material in the 500–1000 Hz range, as measured according to JIS A 1405-1, can be set to 0.45 or higher, or even 0.5 or higher. Similarly, considering the same point of view, the maximum vertical incident sound absorption rate of the sound-absorbing material in the 500–1000 Hz range can be set to 0.65 or higher, or even 0.7 or higher.

[0065] <Manufacturing Methods of Sound-Absorbing Materials>

[0066] Sound-absorbing materials can be manufactured by laminating layers. Regarding sound-absorbing materials, they can be used either with the layers bonded together using adhesive layers, as described above, or without bonding the layers. Furthermore, adhesive layers can be provided only between a portion of the layers. The laminate constituting the sound-absorbing material can be used while housed within a frame.

[0067] <Applications of Sound Absorbing Materials>

[0068] The aforementioned sound-absorbing materials not only exhibit excellent sound absorption characteristics in the low-frequency region but also demonstrate superior durability. Therefore, these materials are suitable for applications in automobiles, railway vehicles, aircraft, ships, residential buildings, and other similar applications. The low-frequency region referred to here can be defined as the area below 1000Hz, and the aforementioned sound-absorbing materials exhibit excellent sound absorption characteristics in the 250–1000Hz frequency range, particularly in the 500–1000Hz frequency range.

[0069] <Vehicle Components>

[0070] The vehicle component incorporates the aforementioned sound-absorbing material. Examples of vehicle components include the following. The vehicle component may be an automobile component.

[0071] Exterior: Vehicle components and vehicle exterior materials that serve as sound-absorbing components for vehicle exterior materials.

[0072] As exterior fittings, examples include (vehicle) undercovers or underbody protectors, soundproof covers, etc., specifically engine undercovers, floor undercovers, rear undercovers, gearbox covers, fender bushings / protectors, or mudguards, etc.

[0073] Interior: Vehicle components and vehicle interior materials that serve as sound-absorbing components for vehicle interiors.

[0074] As interior components, examples include vehicle mufflers and vehicle soundproofing bodies, specifically headliner materials (roof mufflers), dashboard mufflers, floor mufflers, floor carpets, and hood mufflers.

[0075] Other: Sound-absorbing materials for tires.

[0076] As a sound-absorbing material for tires, examples include sound-absorbing structures obtained by combining vehicle covers, shells, etc., with the aforementioned sound-absorbing material.

[0077] The following is a list of the contents of this implementation method.

[0078] A sound-absorbing material comprising, in sequence: a protective layer, a first substrate layer having a connecting hole, and a second substrate layer having a connecting hole, wherein the softness and toughness value of the protective layer is expressed by the following formula (I) as 1 to 75 [MPa / μm].

[0079] Softness and toughness value = (tensile elastic modulus of the protective layer at 25℃ [MPa] × Shore A hardness of the protective layer) / thickness of the protective layer [μm] ···(I)

[0080] In the aforementioned sound-absorbing materials, the protective layer is a layer containing an elastomer.

[0081] In the aforementioned sound-absorbing materials, the protective layer is non-woven fabric.

[0082] In the aforementioned sound-absorbing material, a resin layer is further provided between the protective layer and the first substrate layer.

[0083] In the aforementioned sound-absorbing materials, the resin layer comprises polyolefin, polyester, or polyamide.

[0084] In the aforementioned sound-absorbing materials, a metal vapor-deposited layer is further provided on at least one surface of the resin layer.

[0085] In the aforementioned sound-absorbing materials, the first substrate layer and the second substrate layer are resin foam or non-woven fabric.

[0086] In the aforementioned sound-absorbing material, the thickness of the first substrate layer is thinner than the thickness of the second substrate layer.

[0087] The thickness of the aforementioned sound-absorbing material is 1–100 mm.

[0088] A vehicle component having the aforementioned sound-absorbing material.

[0089] Example

[0090] The present invention will be described in more detail below through embodiments, but the present invention is not limited to these embodiments.

[0091] (Preparation of the substrate layer)

[0092] Substrate 1: PET nonwoven fabric (basic weight 200g / m²) 2 Thickness 3mm)

[0093] Substrate 2: PET nonwoven fabric (basic weight 250g / m²) 2 Thickness 7mm)

[0094] (Preparation of the protective layer)

[0095] The protective layers shown in Tables 1, 2 and 3 were prepared.

[0096] Thickness: The protective layer was cut into 200mm × 200mm pieces and measured using a thickness gauge (JAN-257 digital thickness gauge with a φ20mm probe, manufactured by OZAKI MFG.CO.,LTD.). Measurements were taken at the center and four corners, for a total of five locations. The average value of these measurements was taken as the thickness of the protective layer.

[0097] Tensile modulus of elasticity: This was determined using a tensile testing machine (manufactured by EZ-Test and SHIMADZU CORPORATION). A 20mm × 50mm sample was prepared, and the maximum modulus of elasticity measured at 25°C when the sample was stretched using the tensile testing machine at a tensile speed of 100mm / min was taken as the tensile modulus of elasticity. When both the TD and MD directions were present, the direction with the lower modulus of elasticity was used. Three measurements were performed, and the average value was taken as the tensile modulus of elasticity of the protective layer.

[0098] Shore A hardness: Measured using a type A hardness tester. A 20mm × 50mm sample was prepared, and the samples were stacked to a thickness of at least 1mm. The hardness measured using the hardness tester was taken as the Shore A hardness. Measurements were taken at the center and four corners, for a total of five locations. The average value of these measurements was taken as the Shore A hardness of the protective layer.

[0099] [Table 1]

[0100]

[0101] [Table 2]

[0102]

[0103] [Table 3]

[0104]

[0105]

[0106] (Preparation of the resin layer)

[0107] The following resin layers were prepared.

[0108] Double-sided aluminum vapor-deposited polyethylene terephthalate film (AlPET): 12μm thick

[0109] (Preparation of the adhesive layer)

[0110] The following adhesive layer was prepared.

[0111] Double-sided tape: Showa Denko Materials Co., Ltd., Hi-bon 11-652, 0.12mm thickness

[0112] (Making of sound-absorbing materials)

[0113] Sound-absorbing materials with the structures shown in Tables 4 and 5 were fabricated. Double-sided tape was used to bond the layers together.

[0114] (Evaluation of the sound absorption characteristics of sound-absorbing materials)

[0115] The vertical incident absorption rates of the fabricated sound-absorbing materials were measured as follows. Sound was incident from the protective layer side. The average vertical incident absorption rate in the range of 500–1000 Hz was calculated as the average absorption rate, and the maximum vertical incident absorption rate was taken as the maximum absorption rate. When the average absorption rate was ≥0.45 and the maximum absorption rate was ≥0.65, the sound absorption characteristics in the low-frequency region (500–1000 Hz) were considered excellent. The results are shown in Tables 4 and 5.

[0116] Device Name: Type 4206 Impedance Transistor (Bruel & Kjaer)

[0117] Measurement method: Absorption rate at vertical incidence (according to JIS A 1405-1)

[0118] Measurement range: 50~1600Hz

[0119] (Durability evaluation of sound-absorbing materials)

[0120] The durability (chipping resistance) of each sound-absorbing material was evaluated. The evaluation was conducted using a JA400 flystone testing machine (manufactured by Suga Test Instruments Co., Ltd.), where 850g of No. 7 gravel was impacted into the protective layer at a pressure of 0.4 MPa. The surface condition of the protective layer was then visually inspected, and durability was evaluated according to the following criteria. A rating of A or B was considered excellent durability. The results are shown in Tables 4 and 5.

[0121] A: There are no holes or drill marks.

[0122] B: There are no holes, but there are punch marks.

[0123] C: Holes exist (less than 5 locations).

[0124] D: Holes exist (more than 5 locations).

[0125] [Table 4]

[0126]

[0127] [Table 5]

[0128]

[0129]

[0130] Symbol Explanation

[0131] 1-Protective layer, 2-First substrate layer with connecting holes, 3-Second substrate layer with connecting holes, 4-Resin layer, 10, 20-Sound absorbing material.

Claims

1. A sound-absorbing material, comprising, in sequence, a protective layer, a first substrate layer having communicating holes, and a second substrate layer having communicating holes, wherein, The softness and toughness value of the protective layer, expressed by the following formula (I), is 1 to 75 [MPa / μm]. Softness and toughness value = (tensile elastic modulus of the protective layer at 25℃ [MPa] × Shore A hardness of the protective layer) / thickness of the protective layer [μm] ··· (I).

2. The sound-absorbing material according to claim 1, wherein, The protective layer is a layer containing an elastomer.

3. The sound-absorbing material according to claim 1, wherein, The protective layer is made of non-woven fabric.

4. The sound-absorbing material according to any one of claims 1 to 3, wherein, A resin layer is further provided between the protective layer and the first substrate layer.

5. The sound-absorbing material according to claim 4, wherein, The resin layer comprises polyolefin, polyester, or polyamide.

6. The sound-absorbing material according to claim 4, wherein, A metal vapor-deposited layer is further provided on at least one surface of the resin layer.

7. The sound-absorbing material according to any one of claims 1 to 3, wherein, The first substrate layer and the second substrate layer are resin foam or non-woven fabric.

8. The sound-absorbing material according to any one of claims 1 to 3, wherein, The thickness of the first substrate layer is thinner than the thickness of the second substrate layer.

9. The sound-absorbing material according to any one of claims 1 to 3, wherein the thickness is 1 to 100 mm.

10. A vehicle component comprising the sound-absorbing material according to any one of claims 1 to 9.

Images