Sound-absorbing material and vehicle member

Abstract

Provided is a sound absorbing material comprising, in the following order, a protection layer, a first base material layer having a communication hole, and a second base material layer having a communication hole, the protection layer having a flexibility and toughness value of 1–75 [MPa / μm] as represented by the following formula (I).　Flexibility and toughness value = (tensile modulus [MPa] of protection layer at 25°C × Shore A hardness of protection layer) / thickness [μm] of protection layer (I)

Description

Technical Field

[0001] The present invention relates to a sound-absorbing material and a vehicle member.

Background Art

[0002] As a sound-absorbing material excellent in sound-absorbing characteristics in the low-frequency range, a sound-absorbing material formed by laminating two layers of non-woven fabric or the like is known (for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the case of a sound-absorbing material formed of non-woven fabric, there is room for improvement particularly in terms of durability against external mechanical impacts.

[0005] The present invention has been made in view of the above circumstances, and an object thereof is to provide a sound-absorbing material excellent in sound-absorbing characteristics and durability in the low-frequency range. Another object of the present invention is to provide a vehicle member including the sound-absorbing material.

Means for Solving the Problems

[0006] One aspect of the present invention relates to a sound-absorbing material including, in this order, a protective layer, a first base material layer having communication holes, and a second base material layer having communication holes, wherein a flexible toughness value represented by the following formula (I) of the protective layer is 1 to 75 [MPa / μm]. Flexible toughness value = (tensile elastic modulus [MPa] of the protective layer at 25°C × Shore A hardness of the protective layer) / protective layer thickness [μm] ··· (I)

[0007] In one embodiment, the protective layer may be a layer containing an elastomer.

[0008] In one aspect, the protective layer may be a non-woven fabric.

[0009] In one aspect, the sound-absorbing material may further include a resin layer between the protective layer and the first base material layer.

[0010] In one aspect, the resin layer may contain polyolefin, polyester or polyamide.

[0011] In one aspect, the sound-absorbing material may further include a metal vapor deposition layer on at least one surface of the resin layer.

[0012] In one aspect, the first base material layer and the second base material layer may be a resin foam or a non-woven fabric.

[0013] In one aspect, the thickness of the first base material layer may be thinner than the thickness of the second base material layer.

[0014] In one aspect, the thickness of the sound-absorbing material may be 1 to 100 mm.

[0015] One aspect of the present invention relates to a vehicle member including the above-described sound-absorbing material.

Effects of the Invention

[0016] According to the present invention, it is possible to provide a sound-absorbing material excellent in sound absorption characteristics and durability in a low frequency region. Further, according to the present invention, it is possible to provide a vehicle member including the sound-absorbing material.

Brief Description of the Drawings

[0017]

Figure 1

Figure 2

Modes for Carrying Out the Invention

[0018] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings as appropriate. In this specification, a numerical range indicated by using "~" indicates a range including the numerical values described before and after "~" as the minimum value and the maximum value, respectively. Also, in the numerical ranges described in this specification, the upper limit value or the lower limit value of the numerical range may be replaced with the value shown in the examples.

[0019] <Sound-absorbing material> FIG. 1 is a schematic cross-sectional view of a sound-absorbing material according to an embodiment. The sound-absorbing material 10 includes, in this order, a protective layer 1, a first base layer 2 having communication holes as a base layer, and a second base layer 3 having communication holes. Sound (acoustic energy) incident from the protective layer side is dissipated as heat energy when passing through the sound-absorbing material. Thereby, attenuation of sound is observed.

[0020] FIG. 2 is a schematic cross-sectional view of a sound-absorbing material according to an embodiment. The sound-absorbing material 20 includes, in this order, a protective layer 1, a resin layer 4, a first base layer 2 having communication holes as a base layer, and a second base layer 3 having communication holes.

[0021] (Base layer) Examples of the base layer having communication holes include resin foams, nonwoven fabrics, polymer porous bodies, porous ceramics, etc. Among these, from the viewpoint of excellent sound absorption characteristics in the low frequency range, the base layer may be a resin foam or a nonwoven fabric. The first base layer and the second base layer may be made of the same material or different materials.

[0022] Examples of the material of the resin foam include, for example, polyethylene resin, polypropylene resin, polyurethane resin, polyester resin, acrylic resin, polystyrene resin, melamine resin, silicone resin, natural rubber, synthetic rubber, etc. From the viewpoints of heat resistance, flame retardancy, etc., the material of the resin foam may be a melamine resin.

[0023] Examples of the fibers constituting the nonwoven fabric include organic fibers and inorganic fibers. Examples of the organic fibers include polyolefin fibers such as polyethylene (low density or high density), polypropylene (PP), copolymerized polyethylene, and copolymerized polypropylene; polyester fibers such as polyethylene terephthalate (PET), polytrimethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, and polybutylene naphthalate; polyamide fibers; acrylic fibers; nylon fibers; natural fibers such as rayon fibers and wool. Examples of the inorganic fibers include glass fibers, metal fibers, ceramic fibers, and carbon fibers. The fibers constituting the nonwoven fabric can include one or more of these fibers.

[0024] From the viewpoint of excellent sound absorption characteristics in the low-frequency region, the thickness of the base material layer can be 0.1 to 50 mm, and may be 0.5 to 20 mm, or may be 2.0 to 10 mm. The first base material layer and the second base material layer may 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 base material layer (the base material layer on the sound incident side) may be thinner than the thickness of the second base material layer.

[0025] From the viewpoint of excellent sound absorption characteristics in the low-frequency region, the basis weight of the base material layer can be 50 to 2000 g / m 2 and may be 100 to 1000 g / m 2

[0026] From the viewpoint of excellent sound absorption characteristics in the low-frequency region, the sound absorption material may further include another base material layer having communication holes. That is, the sound absorption material may include, in addition to the first base material layer having communication holes and the second base material layer having communication holes, a third base material layer having communication holes, a fourth base material layer having communication holes, and the like. Each base material layer may be composed of the same material or different materials.

[0027] (Protective layer) ​The flexibility and toughness value of the protective layer represented by the following formula (I) is 1 to 75 MPa / μm. From the perspective of achieving a higher level of balance between sound absorption characteristics and durability, the flexibility and toughness value may be 2 to 70 MPa / μm, or may be 5 to 65 MPa / μm. Flexibility and toughness value = (Tensile modulus of elasticity [MPa] of the protective layer at 25°C × Shore A hardness of the protective layer) / Thickness of the protective layer [μm] ···(I)

[0028] The flexibility and toughness value is a characteristic value set by focusing on the impact absorption degree per unit thickness of the protective layer and the impact durability. The impact absorption degree per unit thickness can be evaluated based on the Shore A hardness, and the impact durability can be evaluated based on the tensile modulus of elasticity. The fact that the product of both is within a predetermined range indicates that the protective layer is moderately flexible and tough.

[0029] The tensile modulus of elasticity is measured by a tensile testing machine. Specifically, a sample of 20 mm × 50 mm is prepared, and the maximum value of the elastic modulus at 25°C when this sample is pulled at a tensile speed of 100 mm / min using a tensile testing machine is taken as the above-mentioned tensile modulus of elasticity. There are no particular restrictions as long as the above formula is satisfied, but from the perspective of durability, the tensile modulus of elasticity can be 1 to 2000 MPa, or may be 10 to 1000 MPa.

[0030] The Shore A hardness is measured by a durometer (type A). Specifically, a sample of 20 mm × 50 mm is prepared, the samples are stacked so that the thickness is 1 mm or more, and they are left standing in an environment of 25°C for 1 hour. The value within 1 second (or the value indicated immediately after measurement) when the hardness of the sample after standing is measured with a durometer is taken as the above-mentioned Shore A hardness. There are no particular restrictions as long as the above formula is satisfied, but from the perspective of durability, the Shore A hardness can be 20 to 95, or may be 30 to 92.

[0031] The thickness of the protective layer is measured by a thickness measuring instrument. There are no particular restrictions as long as the above formula is satisfied, but from the perspective of durability, the thickness of the protective layer can be 10 to 2000 μm, or may be 50 to 500 μm.

[0032] In order to make the soft toughness value fall within the above-mentioned predetermined range, it is conceivable to adjust each characteristic from the following viewpoints, for example. Examples of methods for adjusting the elastic modulus and Shore A hardness include adjusting the density of the protective layer, imparting a rigid component to the material, increasing the proportion of inorganic components such as metal, ceramic, and silica in the material, etc. The elastic modulus and Shore A hardness can also be adjusted by adjusting the amount of voids in the protective layer. The elastic modulus and Shore A hardness can also be adjusted by the skeletal components constituting the protective layer having voids, the thickness of the skeleton, the method of binding the skeleton, etc. Adjustment of either one of the elastic modulus and Shore A hardness can be achieved, for example, by appropriately combining the methods mentioned above. For example, while providing voids in the protective layer and thickening the skeleton constituting the protective layer, the Shore A hardness can be decreased while maintaining the elastic modulus.

[0033] From the viewpoint of achieving a higher level of compatibility between sound absorption characteristics and durability, the protective layer may be a layer containing an elastomer. Examples of elastomers that can satisfy the above-mentioned soft toughness value include thermoplastic elastomers and thermosetting elastomers. Examples of thermoplastic elastomers include resins such as polyolefin-based, polystyrene-based, polyurethane-based, polyester-based, polyether-based, polyacrylic-based, polyamide-based, vinyl chloride, chlorinated polyethylene-based, polydiene-based, fluorine-based, silicone-based, polycarbonate-based, etc., or modified resins thereof. Examples of thermosetting elastomers include resins such as fluorine-based, silicone-based, urethane-based, epoxy-based, etc., synthetic rubbers or natural rubbers such as isoprene rubber, ethylene propylene rubber, ethylene propylene diene rubber, nitrile rubber (NBR), etc., or modified resins thereof. From the viewpoints of thinning for weight reduction, heat resistance, durability, etc., polyurethane-based or polyester-based resins are preferred.

[0034] The layer containing the elastomer may contain other components in addition to the elastomer. Examples of other components include inorganic particles such as silica, alumina, and talc, metal particles, organic resin particles, etc. from the viewpoint of improving heat resistance, durability, sound absorption, vibration damping, sound insulation, etc., and hollow particles, etc. from the viewpoint of weight reduction. From the viewpoint of weight reduction, the layer containing the elastomer may contain a foamed material, bubble portions by foam molding, etc.

[0035] From the viewpoint of achieving a higher level of compatibility between sound absorption characteristics and durability, the protective layer may be a non-woven fabric. Examples of non-woven fabrics that can satisfy the above-mentioned flexible toughness value include non-woven fabrics in which the fibers are firmly bonded from the viewpoint of durability, such as non-woven fabrics (PET non-woven fabrics, etc.) manufactured by the chemical bonding method, thermal bonding method, needle punching method, etc.

[0036] The basis weight (weight per unit area) of the protective layer can be 10 to 1000 g / m 2 and may be 50 to 800 g / m 2

[0037] The density of the protective layer can be 0.1 to 10.0 g / cm 3 and may be 0.2 to 2.0 g / cm 3

[0038] When the protective layer is a non-woven fabric, the average fiber diameter of the fibers constituting the non-woven fabric can be 0.1 to 100 μm and may be 1 to 50 μm from the viewpoint of achieving a higher level of compatibility between sound absorption characteristics and durability.

[0039] The average fiber diameter is obtained by taking the average of the fiber diameters of individual fibers photographed at 1000 times magnification with an electron microscope. Specifically, the average fiber diameter is obtained by measuring the fiber diameters of a total of 100 fibers arbitrarily selected from 10 photographs up to the order of 0.1 μm in diameter, averaging them, and rounding off the second decimal place.

[0040] ​​(Resin layer) From the viewpoints of improving sound absorption characteristics, durability, imparting functionality, etc., the sound-absorbing material may further include a resin layer between the protective layer and the base material layer. Examples of the resin constituting the resin layer include polyolefin resins such as polyethylene (low density or high density), polypropylene (stretched or unstretched), copolymerized polyethylene, copolymerized polypropylene, etc., polyester resins such as polyethylene terephthalate, polytrimethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, etc., fluorine-based resins such as PTFE, FEP, PFA, etc., polyimide-based resins, polyamide-based resins, aramid-based resins, vinyl chloride-based resins, acrylic-based resins, polycarbonate-based resins, polyphenylene sulfide-based resins, polyvinyl alcohol-based resins, polystyrene-based resins, polyacrylonitrile-based resins, ethylene-vinyl acetate-based resins, and the like. The resin layer is a layer (film) having no communication holes.

[0041] From the viewpoint of excellent sound absorption characteristics in the low-frequency region, the thickness of the resin layer can be 0.5 to 500 μm, may be 5 to 250 μm, or may be 10 to 100 μm.

[0042] From the viewpoints of the function of improving the sound absorption effect by adjusting the film properties and imparting the heat ray reflection function, the resin layer may be provided with a metal vapor deposition layer on its surface. That is, the sound-absorbing material may further include a metal vapor deposition layer on the surface of the resin layer. The metal vapor deposition layer can be formed by physical vapor deposition such as vacuum vapor deposition or chemical vapor deposition of metals such as aluminum, copper, zinc, zinc alloy, silver, etc. The metal vapor deposition layer may be provided on both sides of the resin layer or on one side thereof.

[0043] The resin layer may be a perforated film from the viewpoint of improving the sound absorption effect in the low-frequency range and adjusting the sound absorption frequency peak. The perforated film may have holes arranged in a lattice pattern or a rhombus pattern. From the viewpoint of excellent sound absorption characteristics in the low-frequency range, the holes may be circular with a diameter of 0.1 to 50.0 mm, may be circular with a diameter of 0.2 to 10.0 mm, or may be circular with a diameter of 0.3 to 5.0 mm. The shape of the holes may be circular, elliptical, rectangular, polygonal, or the like.

[0044] (Adhesive layer) The sound-absorbing material may further include an adhesive layer between each of the above layers. The sound-absorbing material may include an adhesive layer between at least one of the protective layer and the first base material layer and between the first base material layer and the second base material layer. Further, the sound-absorbing material may include an adhesive layer between at least one of the protective layer and the resin layer, between the resin layer and the first base material layer, and between the first base material layer and the second base material layer.

[0045] Examples of the adhesive layer include a layer containing an adhesive component such as vinyl acetate resin, polyolefin resin, ethylene-vinyl acetate copolymer resin, isobutene-maleic anhydride copolymer resin, acrylic copolymer resin, acrylic monomer, acrylic oligomer, styrene-butadiene rubber, vinyl chloride resin, chloroprene rubber, nitrile rubber, urethane resin, silylated urethane resin, epoxy resin, modified epoxy resin, polyethylene resin, ionomer resin, silicone resin, modified silicone resin, water glass, silicate, or a laminate (for example, double-sided tape) having a layer containing these adhesive components on both sides of a support made of paper, cloth, resin film, metal tape, or the like. Each adhesive layer may be composed of the same material or different materials.

[0046] The thickness of the adhesive layer is not particularly limited, but it can be 0.01 to 500 μm, and may be 1 to 250 μm. Each adhesive layer may have the same thickness or different thicknesses.

[0047] The weight of the adhesive layer is not particularly limited, but it is 1 to 500 g / m 2can be set to 5 to 200 g / m 2 and may be 10 to 150 g / m 2 Each adhesive layer may have the same weight or different weights.

[0048] The thickness of the sound-absorbing material can be set to 1 to 100 mm, may be 2 to 50 mm, or may be 5 to 30 mm from the viewpoints of the manifestation of sound-absorbing characteristics, the workability of the material, space saving, etc.

[0049] The average normal incidence sound absorption coefficient of the sound-absorbing material measured in accordance with JIS A 1405-1 at 500 to 1000 Hz can be 0.45 or more, and may be 0.5 or more from the viewpoint of excellent sound-absorbing characteristics in the low-frequency region. From the same viewpoint, the maximum normal incidence sound absorption coefficient of the sound-absorbing material at 500 to 1000 Hz can be 0.65 or more, and may be 0.7 or more.

[0050] <Method for manufacturing sound-absorbing material> The sound-absorbing material can be manufactured by laminating each layer. The sound-absorbing material may be used in a state where each layer is adhered by providing the adhesive layer as described above, or may be used without each layer being adhered. Also, an adhesive layer may be provided only between some layers. The laminate constituting the sound-absorbing material may be used in a state of being housed in a housing.

[0051] <Use of sound-absorbing material> The above sound-absorbing material is not only excellent in sound-absorbing characteristics in the low-frequency region but also excellent in durability. Therefore, the above sound-absorbing material can be suitably used in applications such as automobiles, railway vehicles, airplanes, ships, and buildings such as houses. The low-frequency region mentioned here can be a region where the frequency is 1000 Hz or less, and the above sound-absorbing material has excellent sound-absorbing characteristics in the frequency region of 250 to 1000 Hz, particularly 500 to 1000 Hz.

[0052] <Vehicle member> The vehicle member is provided with the above sound-absorbing material. Examples of the vehicle member include the following aspects. The vehicle member may be an automotive member. Exterior: A vehicle member that is a sound-absorbing member of a vehicle exterior material, a vehicle exterior material. Examples of the exterior include (vehicle) undercovers or under protectors, soundproof covers, etc., and specifically, engine undercovers, floor undercovers, rear undercovers, transmission covers, fender liners / protectors or mudguards, etc. Interior: A vehicle member that is a sound-absorbing member of a vehicle interior material, a vehicle interior material. Examples of the interior include vehicle silencers, vehicle soundproofing bodies, etc., and specifically, ceiling materials (roof silencers), dash silencers, floor silencers, floor carpets, hood silencers, etc. Others: Sound-absorbing material for tires. Examples of the sound-absorbing material for tires include a sound-absorbing structure formed by combining a vehicle cover, a case, etc. with the above sound-absorbing material.

[0053] The contents of this embodiment are listed below. A sound-absorbing material comprising a protective layer, a first base material layer having communication holes, and a second base material layer having communication holes, in this order, wherein the flexible toughness value of the protective layer represented by the following formula (I) is 1 to 75 [MPa / μm]. Flexible toughness value = (tensile modulus of elasticity [MPa] of the protective layer at 25°C × Shore A hardness of the protective layer) / thickness of the protective layer [μm] ··· (I) The above sound-absorbing material, wherein the protective layer is a layer containing an elastomer. The above sound-absorbing material, wherein the protective layer is a non-woven fabric. The above sound-absorbing material, further comprising a resin layer between the protective layer and the first base material layer. The above sound-absorbing material, wherein the resin layer contains a polyolefin, a polyester, or a polyamide. The above sound-absorbing material, further comprising a metal vapor deposition layer on at least one surface of the resin layer. The above sound-absorbing material, wherein the first base material layer and the second base material layer are resin foams or non-woven fabrics. The above sound-absorbing material, wherein the thickness of the first base material layer is thinner than the thickness of the second base material layer. The sound-absorbing material described above with a thickness of 1 to 100 mm. A vehicle member including the sound-absorbing material described above.

Example

[0054] Hereinafter, the present invention will be described in more detail by way of examples, but the present invention is not limited to these examples.

[0055] (Preparation of base material layer) Base material 1: PET non-woven fabric (basis weight 200 g / m 2 , thickness 3 mm) Base material 2: PET non-woven fabric (basis weight 250 g / m 2 , thickness 7 mm)

[0056] (Preparation of protective layer) The protective layers shown in Table 1, Table 2 and Table 3 were prepared. Thickness: The protective layer was cut into a size of 200 mm × 200 mm and measured with a thickness measuring instrument (Digital Thickness Gauge JAN-257, measuring head φ20 mm, manufactured by Oike Seisakusho Co., Ltd.). The measurement points were a total of 5 points including the center and the four corners, and the average value was taken as the thickness of the protective layer. Tensile modulus of elasticity: Measured with a tensile testing machine (EZ-Test, manufactured by Shimadzu Corporation). A sample of 20 mm × 50 mm was prepared, and the maximum elastic modulus at 25 °C when this was pulled at a tensile speed of 100 mm / min using the tensile testing machine was taken as the above-mentioned tensile modulus of elasticity. When there were a TD direction and an MD direction, the one with the lower elastic modulus was adopted. The number of measurements was 3 times, and the average value was taken as the tensile modulus of elasticity of the protective layer. Shore A hardness: Measured with a durometer (Type A). A sample of 20 mm × 50 mm was prepared, and samples were stacked so that the thickness was 1 mm or more, and the hardness measured with a durometer for this was taken as the Shore A hardness. The measurement points were a total of 5 points including the center and the four corners, and the average value was taken as the Shore A hardness of the protective layer.

[0057]

Table 1

[0058]

Table 2

[0059]

Table 3

[0060] (Preparation of resin layer) The following resin layers were prepared. Double-sided aluminum vapor-deposited polyethylene terephthalate film (AlPET): thickness 12 μm

[0061] (Preparation of adhesive layer) The following adhesive layers were prepared. Double-sided tape: Showa Denko Materials Co., Ltd., Hibon 11-652, thickness 0.12 mm

[0062] (Fabrication of sound-absorbing material) Sound-absorbing materials having the configurations shown in Table 4 and Table 5 were fabricated. A double-sided tape was used for bonding each layer.

[0063] (Evaluation of sound absorption characteristics of sound-absorbing material) The normal incidence sound absorption rate of each fabricated sound-absorbing material was measured as follows. Sound was incident from the protective layer side. The average value of the normal incidence sound absorption rate in the range of 500 to 1000 Hz was calculated as the average sound absorption rate, and the maximum value of the normal incidence sound absorption rate was taken as the maximum sound absorption rate. When the average sound absorption rate was 0.45 or more and the maximum sound absorption rate was 0.65 or more, it was determined that the sound absorption characteristics in the low frequency range (500 to 1000 Hz) were excellent. The results are shown in Table 4 and Table 5. Apparatus name: Type 4206 impedance tube (Brüel & Kjær) Measurement method: Normal incidence sound absorption rate (conforming to JIS A 1405-1) Measurement range: 50 to 1600 Hz

[0064] (Evaluation of durability of sound-absorbing material) The durability (chipping resistance) of each of the produced sound-absorbing materials was evaluated. For the evaluation, a flying gravel tester JA400 (manufactured by Suga Test Instruments Co., Ltd.) was used, and 850 g of No. 7 crushed stone was applied to the protective layer at a pressure of 0.4 MPa. Subsequently, the state of the surface of the protective layer was visually confirmed, and the durability was evaluated according to the following criteria. When the evaluation was A or B, it was judged that the durability was excellent. The results are shown in Tables 4 and 5. A: No holes or indentations. B: No holes, but there are indentations. C: There are holes (less than 5 locations). D: There are holes (5 locations or more).

[0065]

Table 4

[0066]

Table 5

Explanation of Symbols

[0067] 1... Protective layer, 2... First base material layer having communication holes, 3... Second base material layer having communication holes, 4... Resin layer, 10, 20... Sound-absorbing material.

Claims

1. An acoustic material comprising, in order, a protective layer, a first base material layer having a through-hole, and a second base material layer having a through-hole, wherein a flexibility toughness value represented by the following formula (I) of the protective layer is 1 to 75 [MPa / μm]. Flexibility toughness value = (tensile modulus [MPa] of the protective layer at 25°C × Shore A hardness of the protective layer) / thickness of the protective layer [μm]... (I)

2. The acoustic material according to claim 1, wherein the protective layer is a layer containing an elastomer.

3. The acoustic material according to claim 1, wherein the protective layer is a non-woven fabric.

4. The acoustic material according to any one of claims 1 to 3, further comprising a resin layer between the protective layer and the first base material layer.

5. The acoustic material according to claim 4, wherein the resin layer contains a polyolefin, a polyester or a polyamide.

6. The acoustic material according to claim 4 or 5, further comprising a metal vapor deposition layer on at least one surface of the resin layer.

7. The acoustic material according to any one of claims 1 to 6, wherein the first base material layer and the second base material layer are a resin foam or a non-woven fabric.

8. The acoustic material according to any one of claims 1 to 7, wherein the thickness of the first base material layer is thinner than the thickness of the second base material layer.

9. The acoustic material according to any one of claims 1 to 8, having a thickness of 1 to 100 mm.

10. A vehicle member comprising the acoustic material according to any one of claims 1 to 9.

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