sound-absorbing material

Abstract

This sound-absorbing material has three or more layers of non-woven fabric including a first spun-bond non-woven fabric, a melt-blown non-woven fabric and a second spun-bond non-woven fabric. The sound-absorbing material comprises, in the following order along the layer thickness direction from the side of an entry surface which sound permeates: a layer A having air permeability of not more than 48 cc / cm2 / sec; a layer B which is a layer or a foamed body having air permeability of 20 cc / cm2 / sec to 4500 cc / cm2 / sec; a layer C having the three or more layers of non-woven fabric including the first spun-bond non-woven fabric, the melt-blown non-woven fabric and the second spun-bond non-woven fabric, and having air permeability of not more than 48 cc / cm2 / sec; and a layer D which is a layer, a foamed body, or a rear air layer having an air permeability of 20 cc / cm2 / sec to 4500 cc / cm2 / sec.

Description

[Technical Field]

[0001] The present disclosure relates to sound absorbing materials. [Background technology]

[0002] Sound-absorbing materials are products that have the function of absorbing sound and are widely used in fields such as automobiles, housing, and electrical appliances, but in recent years, as products have become more sophisticated, the noise environment has become more complex, and the need for sound absorption has also become more advanced.For example, in the automotive industry, while the spread of electric vehicles has made car interiors and engine noise quieter, there is a need to reduce noise in the frequency range of 1000Hz to 6000Hz, such as motor noise and wind noise, which is said to lower the minimum audible threshold for humans.

[0003] Glass wool, rock wool, aluminum fiber, expanded foam, porous ceramics, and the like have traditionally been used as sound-absorbing materials with excellent sound-absorbing properties. However, alternatives to these sound-absorbing materials are being considered from the perspectives of their impact on human health, recyclability, and environmental compatibility. Nonwoven fabrics made by entangling or bonding synthetic fibers have been widely used as alternative sound-absorbing materials in recent years because they are inexpensive and have good moldability. In particular, the sound-absorbing performance of nonwoven fabrics made from synthetic fibers is relatively good in the high-frequency range. In automobiles and other applications, there is a demand for lighter sound-absorbing materials with excellent sound-absorbing performance. As a method for improving sound-absorbing performance, it has been proposed to use two or more layers of different synthetic fibers stacked together (for example, Patent Publication No. 2021-113879). Summary of the Invention [Problem to be solved by the invention]

[0004] As a result of investigations by the inventors, it was discovered that sound-absorbing materials made by laminating different synthetic fibers, such as the laminate proposed in Patent Document 1, exhibit excellent sound absorption coefficients in specific frequency ranges, but that there may be variations in sound absorption coefficients outside of those frequency ranges (for example, the high frequency range of 1000 Hz to 6000 Hz, where the minimum audible threshold for humans is said to decrease).

[0005] The present disclosure has been made in light of the above findings, and aims to provide a sound-absorbing material that exhibits excellent sound absorption properties over a wide frequency range from 1000 Hz onwards, which is the high frequency range, and that has reduced variation in sound absorption coefficient in the frequency range. [Means for solving the problem]

[0006] Specific means for solving the above problems are as follows. <1> The nonwoven fabric has three or more layers including a first spunbond nonwoven fabric, a meltblown nonwoven fabric, and a second spunbond nonwoven fabric, and has an air permeability of 48 cc / cm 2 Layer A is less than / sec, Air permeability is 20cc / cm 2 / sec or more 4500cc / cm 2 Layer B is a layer or foam of 1 / sec or less; The nonwoven fabric has three or more layers including the first spunbond nonwoven fabric, the meltblown nonwoven fabric, and the second spunbond nonwoven fabric, and the air permeability is 48 cc / cm 2 Layer C, which is equal to or less than / sec; Air permeability is 20cc / cm 2 / sec or more 4500cc / cm 2 / sec or less, a layer D which is a foam or a back air layer; A sound-absorbing material having the above in the layer thickness direction from the incident surface side where sound is incident. <2> The sum ΣACmulti of the product of the air permeability and thickness of the layer A and the product of the air permeability and thickness of the layer C is 10 or more and 60 or less, and the sum ΣACdiv of the air permeability of the layer A divided by its thickness and the air permeability of the layer C divided by its thickness is 50 or more and 200 or less; <1> The sound-absorbing material described in <3> At least one of the layer A and the layer C has four or more layers of nonwoven fabric, in which a third spunbond nonwoven fabric is further laminated on the outermost surface on the sound incident surface side, Air permeability is 12cc / cm 2 / sec or more 48cc / cm 2 / sec or less, the average fiber diameter of the fibers contained in the third spunbond nonwoven fabric is larger than the average fiber diameters of the fibers contained in the first spunbond nonwoven fabric and the second spunbond nonwoven fabric; and, The third spunbonded nonwoven fabric contains fibers having an average fiber diameter of 20 μm or more and 50 μm or less. <1> or <2> The sound-absorbing material described in <4> The layer A and the layer C have the same layer structure. <1> ~ <3> 10. A sound-absorbing material according to any one of the preceding items. <5> At least one of the layer B and the layer D contains a polyester resin. <1> ~ <4> 10. A sound-absorbing material according to any one of the preceding items. <6> Both the layer B and the layer D contain a polyester resin. <5> The sound-absorbing material described in <7> Layer D is a back air layer, <1> ~ <6> 10. A sound-absorbing material according to any one of the preceding items. <8> The average fiber diameter of the fibers contained in at least one of the first spunbonded nonwoven fabric and the second spunbonded nonwoven fabric is 8 μm or more and 30 μm or less. <1> ~ <7> 10. A sound-absorbing material according to any one of the preceding items. <9> The basis weight (g / m 2 ) and the basis weight of the layer B (g / m 2 ) (Layer A or Layer C / Layer B) is 0.50 or more, <1> ~ <8> 10. A sound-absorbing material according to any one of the preceding items. <10> Air permeability of layer A or layer C (cc / cm 2 / sec) and the air permeability of layer B (cc / cm 2 / sec) (Layer A or Layer C / Layer B) is 0.03 or more and 1.00 or less. <1> ~ <9> 10. A sound-absorbing material according to any one of the preceding items. <11> The above-mentioned sound-absorbing material for automobiles. <1> ~ <10> 10. A sound-absorbing material according to any one of the preceding items. <12> The nonwoven fabric is a conductive nonwoven fabric to which a conductive substance is attached or kneaded. <1> ~ <11> 10. A sound-absorbing material according to any one of the preceding items. [Effects of the Invention]

[0007] The present disclosure can provide a sound-absorbing material that exhibits excellent sound absorption properties over a wide frequency range from 1000 Hz onwards, which is the high frequency range, and that has reduced variation in sound absorption coefficient in the frequency range. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a schematic partial cross-sectional view showing an example of the layer structure of a sound-absorbing material according to the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0009] In the present disclosure, a numerical range expressed using "to" means a range that includes the numerical values ​​before and after "to" as the lower and upper limits. In the present disclosure, in the numerical ranges described in stages, the upper or lower limit value described in one numerical range may be replaced with the upper or lower limit value of another numerical range described in stages. Furthermore, in the numerical ranges described in the present disclosure, the upper or lower limit value of the numerical range may be replaced with the value shown in the examples. In the present disclosure, when a plurality of substances corresponding to each component are present in the composition, the amount of each component in the composition means the total amount of the plurality of substances present in the composition, unless otherwise specified. In this disclosure, "mass" and "weight" are synonymous, and "mass %" and "weight %" are synonymous. In the present disclosure, a combination of two or more preferred embodiments is a more preferred embodiment. In the description of groups (atomic groups) in the present disclosure, a description that does not specify whether substituted or unsubstituted includes both groups that do not contain a substituent and groups that contain a substituent. In the present disclosure, the term "layer" includes cases where the layer is formed over the entire area when the area in which the layer exists is observed, as well as cases where the layer is formed over only a portion of the area. In the present disclosure, the term "process" includes not only an independent process but also a process that cannot be clearly distinguished from other processes as long as the intended purpose of the process is achieved. In the present disclosure, the unit of air permeability is "cc / cm 2 / sec" is sometimes abbreviated as "ccs".

[0010] [Sound-absorbing material according to the present disclosure] The sound-absorbing material according to the present disclosure has three or more layers of nonwoven fabric including a first spunbond nonwoven fabric, a meltblown nonwoven fabric, and a second spunbond nonwoven fabric, and has an air permeability of 48 cc / cm 2 / sec or less, and layer A with an air permeability of 20cc / cm 2 / sec or more 4500cc / cm 2 / sec or less or a layer B of a foam, and three or more layers of nonwoven fabric including the first spunbond nonwoven fabric, the meltblown nonwoven fabric, and the second spunbond nonwoven fabric, and the air permeability is 48 cc / cm 2 / sec or less, and layer C with an air permeability of 20cc / cm 2 / sec or more 4500cc / cm 2 / sec or less, a foam, or a layer D which is a back air layer, in this order in the layer thickness direction from the incident surface side where sound is incident.

[0011] Below, the air permeability is 20cc / cm 2 / sec or more 4500cc / cm 2 Layers with a ventilation rate of 1 / sec or less are collectively called "highly breathable layers."

[0012] The sound-absorbing material according to the present disclosure has the above-mentioned configuration, i.e., it is a sound-absorbing material that combines Layer A and Layer C having a predetermined air permeability with Layers B and D, which are layers, foams, or backing air layers having a predetermined air permeability, and thereby exhibits excellent sound absorption properties over a wide frequency range from 1000 Hz onwards, which is the high frequency range. Furthermore, by making Layer A and Layer C three or more layers of nonwoven fabric including a first spunbond nonwoven fabric, a meltblown nonwoven fabric, and a second spunbond nonwoven fabric, variation in sound absorption coefficient in the frequency range is reduced.

[0013] Furthermore, the sound-absorbing material according to the present disclosure has the above-described configuration, i.e., a configuration in which layers A and C containing spunbond nonwoven fabric with fibrous properties that are resistant to pilling are alternately sandwiched between highly breathable layers B and D. Therefore, compared to conventional sound-absorbing materials, the sound-absorbing material has superior abrasion resistance (sandblasting resistance), which is resistance to impacts from solid objects such as hail, sleet, and pebbles.

[0014] FIG. 1 shows an example of the layer structure of a sound-absorbing material according to the present disclosure. The sound-absorbing material 10 shown in Figure 1 comprises an A layer 12 having three or more layers of nonwoven fabric including a first spunbond nonwoven fabric, a meltblown nonwoven fabric, and a second spunbond nonwoven fabric, a highly breathable B layer 14, a C layer 16 having three or more layers of nonwoven fabric including the first spunbond nonwoven fabric, a meltblown nonwoven fabric, and a second spunbond nonwoven fabric, and a highly breathable D layer 18, which are layered in this order in the layer thickness direction from the incident surface side where sound is incident.

[0015] The A layer 12 and the C layer 16 may have the same material, characteristics, and thickness, or may have different materials. The B layer 14 and the D layer 18 may be the same or different in material, characteristics, and thickness.

[0016] The sound-absorbing material according to the present disclosure will now be described in detail.

[0017] The values ​​of basis weight, thickness, air permeability, water pressure resistance, abrasion resistance, tensile strength, and average fiber diameter of the sound-absorbing material and each layer can be obtained by the measurement methods shown in the examples described later.

[0018] <Overall characteristics of the sound-absorbing material according to the present disclosure> Sound absorbing material density The basis weight of the entire sound-absorbing material according to the present disclosure is set to 100 g / m from the viewpoints of improving sound absorption over a wide frequency range and further reducing the variation in sound absorption coefficient in the frequency range, preventing a decrease in workability due to an increase in the weight of the sound-absorbing material, and ensuring the strength of the structure that supports the sound-absorbing material due to an increase in weight. 2 More than 4000g / m 2 Preferably, it is 200 g / m or less. 2 More than 1500g / m 2 More preferably, it is 250 g / m or less. 2 More than 500g / m 2 From the viewpoint of reducing the amount of carbon dioxide emitted, the basis weight of the entire sound-absorbing material according to the present disclosure is preferably 250 g / m or less. 2 More than 400g / m 2 It is preferable that:

[0019] ·Weight: Layer A or Layer C / Layer B The sound-absorbing material according to the present disclosure is characterized in that the basis weight (g / m ) of Layer A or Layer C is set to 1 / 2 mm from the viewpoint of improving sound absorption properties over a wide frequency range and further reducing the variation in sound absorption coefficient in the frequency range. 2 ) and the basis weight of layer B (g / m 2 ) (basis weight: Layer A or Layer C / Layer B) is preferably 0.05 or more, more preferably 0.70 or more, even more preferably 0.10 or more and 1.30 or less, and particularly preferably 0.50 or more and 1.20 or less.

[0020] ·Weight: Layer A or Layer C / Layer D In the sound-absorbing material according to the present disclosure, from the viewpoint of improving sound absorption properties over a wide frequency range and further reducing the variation in sound absorption coefficient in the frequency range, the basis weight (g / m 2 ) and the basis weight of layer D (g / m 2) (Layer A or Layer C / Layer D) is preferably 0.03 or more and 0.60 or less, more preferably 0.30 or more, even more preferably 0.50 or more, and particularly preferably 0.70 or more. In this case, Layer D has an air permeability of 30 cc / cm 2 / sec or more 4500cc / cm 2 / sec or less layer or foam, not a backing air space. The upper limit of the ratio of the basis weight (Layer A or Layer C / Layer D) is not particularly limited, but may be, for example, 1 or less.

[0021] Weight: Layer A / Layer C In the sound-absorbing material according to the present disclosure, the basis weight (g / m) of the layer A is set to 1000 ppm from the viewpoint of improving the sound absorption properties over a wide frequency range and further reducing the variation in the sound absorption coefficient over the frequency range. 2 ) and the basis weight of layer C (g / m 2 ) (Layer A / Layer C) is preferably 0.10 or more and 1.50 or less, more preferably 0.30 or more, and even more preferably 0.70 or more. The upper limit of the ratio of the basis weight (Layer A / Layer C) is not particularly limited, but may be, for example, 5.00 or less.

[0022] Overall thickness of sound absorbing material The overall thickness of the sound-absorbing material according to the present disclosure is preferably 1 mm or more and 80 mm or less, more preferably 5 mm or more, even more preferably 10 mm or more, and even more preferably 30 mm or more, from the viewpoint of improving sound absorption properties over a wide frequency range and further reducing the variation in sound absorption coefficient within the frequency range. The overall thickness of the sound-absorbing material according to the present disclosure is determined from the viewpoint of preventing a decrease in workability due to an increase in the weight of the sound-absorbing material, From the viewpoint of ensuring the strength of the structure that supports the sound absorbing material due to the increased weight, the gap is preferably 100 mm or less, more preferably 80 mm or less, and even more preferably 60 mm or less.

[0023] Thickness: Layer A or Layer C / Layer B In the sound-absorbing material according to the present disclosure, from the viewpoint of improving sound absorption properties over a wide frequency range and further reducing the variation in sound absorption coefficient in the frequency range, the ratio of the thickness (mm) of Layer A or Layer C to the thickness (mm) of Layer B (Layer A or Layer C / Layer B) is preferably 0.01 or more and 1.00 or less, more preferably 0.015 or more and 0.50 or less, and even more preferably 0.02 or more and 0.10 or less.

[0024] Thickness: Layer A or Layer C / Layer D In the sound-absorbing material according to the present disclosure, from the viewpoint of improving sound absorption properties over a wide frequency range and further reducing the variation in sound absorption coefficient in the frequency range, the ratio of the thickness (mm) of Layer A or Layer C to the thickness (mm) of Layer D (Layer A or Layer C / Layer D) is preferably 0.01 or more and 1.00 or less, more preferably 0.015 or more and 0.50 or less, even more preferably 0.02 or more and 0.10 or less, and particularly preferably 0.05 or more and 0.10 or less. In this case, Layer D has an air permeability of 30 cc / cm 2 / sec or more 4500cc / cm 2 / sec or less layer or foam, not a backing air space.

[0025] Thickness: Layer A / Layer C In the sound-absorbing material according to the present disclosure, from the viewpoint of improving sound absorption properties over a wide frequency range and further reducing the variation in sound absorption coefficient in the frequency range, the ratio of the thickness (mm) of Layer A to the thickness (mm) of Layer C (Layer A / Layer C) is preferably 0.1 or more and 5.0 or less, more preferably 0.3 or more, more preferably 0.5 or more, and even more preferably 0.8 or more. The upper limit of the thickness ratio (Layer A / Layer C) is not particularly limited, but may be, for example, 5 or less, or 3.0 or less.

[0026] Air permeability: Layer A or Layer C / Layer B The sound-absorbing material according to the present disclosure has a specific air permeability (cm ) of Layer A or Layer C from the viewpoint of improving sound absorption properties over a wide frequency range and further reducing the variation in sound absorption coefficient in the frequency range. 3 / cm 2 / sec) and the air permeability of layer B (cm 3 / cm 2 / sec) (air permeability: Layer A or Layer C / Layer B) is preferably 0.03 or more and 1.00 or less, more preferably 0.03 or more and 0.80 or less, and even more preferably 0.03 or more and 0.50 or less.

[0027] ·ΣACmulti The sound-absorbing material according to the present disclosure has a structure in which the sum ΣACmulti of the product of the air permeability and thickness of layer A and the product of the air permeability and thickness of layer C improves sound absorption over a wide frequency range and From the viewpoint of further reducing the variation in sound absorption coefficient, it is preferably 10 or more and 60 or less, and more preferably 20 or more and 40 or less. From the same viewpoint as above, ΣACmulti is preferably 10 or more, more preferably 15 or more, and even more preferably 20 or more. From the same viewpoint as above, ΣACmulti is preferably 60 or less, more preferably 50 or less, and even more preferably 40 or less.

[0028] ΣACmulti is the air permeability of layer A (cc / cm 2 / sec) and thickness (mm), and the air permeability (cc / cm 2 This is the sum of the product of the absorption rate (Hz) ( / sec) and the thickness (mm), and indicates the actual amount of resistance that the fiber experiences when sound enters. When this index is within the above range, the sound absorption coefficient in the vicinity of 1000 Hz tends to be better.

[0029] ·ΣACdiv In the sound-absorbing material according to the present disclosure, the sum ΣACdiv of the value obtained by dividing the air permeability of the layer A by the thickness and the value obtained by dividing the air permeability of the layer C by the thickness improves sound absorption properties over a wide frequency range and From the viewpoint of further reducing the variation in sound absorption coefficient in the region, it is preferably 40 or more and 200 or less, more preferably 50 or more and 200 or less, and even more preferably 60 or more and 120 or less. From the same viewpoint as above, ΣACdiv is preferably 40 or more, and more preferably 50 or more. It is more preferable that the ratio is 100 to 1000, and even more preferable that the ratio is 60 or more. From the same viewpoint as above, ΣACdiv is preferably 200 or less, more preferably 150 or less, and even more preferably 120 or less.

[0030] In the sound-absorbing material according to the present disclosure, from the viewpoint of improving sound absorption properties over a wide frequency range and further reducing the variation in sound absorption coefficient over the frequency range, it is preferable that the sum ΣACmulti of the product of the air permeability and thickness of Layer A and the product of the air permeability and thickness of Layer C is 10 or more and 60 or less, and the sum ΣACdiv of the value obtained by dividing the air permeability of Layer A by its thickness and the value obtained by dividing the air permeability of Layer C by its thickness is 50 or more and 200 or less.

[0031] ΣACdiv is the air permeability of layer A (cc / cm 2 / sec) divided by the thickness (mm) and the air permeability of layer C (cc / cm 2 / sec) divided by the thickness (mm), and indicates the degree of interaction between the fiber and the space when sound is incident. When this index is within the above range, the sound absorption coefficient tends to be better in the vicinity of 5000 Hz.

[0032] As described above, by satisfying the above ranges for both ΣACmulti and ΣACdiv, better sound absorption coefficients can be obtained over a wide range, from the low-frequency sound absorption coefficient to the high-frequency sound absorption coefficient.

[0033] ·Layer composition In the sound-absorbing material according to the present disclosure, from the viewpoint of improving sound absorption properties over a wide frequency range and further reducing the variation in sound absorption coefficient in the frequency range, at least one of the layers B and D has an air permeability of 30 cc / cm 2 / sec or more 4500cc / cm 2 / sec or less, and both Layer B and Layer D have an air permeability of 30 cc / cm 2 / sec or more 4500cc / cm2 It is more preferable that the layer has a viscosity of 1 / sec or less.

[0034] In the sound-absorbing material according to the present disclosure, from the viewpoint of improving sound absorption properties over a wide frequency range and further reducing the variation in sound absorption coefficient over the frequency range, it is preferable that at least one of Layer B and Layer D contains a polyester-based resin, and it is more preferable that both Layer B and Layer D contain a polyester-based resin.

[0035] The nonwoven fabric contained in the sound-absorbing material according to the present disclosure may be a conductive nonwoven fabric to which a conductive substance has been attached or kneaded. When the nonwoven fabric is a conductive nonwoven fabric, electromagnetic wave absorption performance can be obtained. Here, the term "nonwoven fabric" refers not only to the nonwoven fabrics of layers A and C (e.g., a first spunbond nonwoven fabric, a meltblown nonwoven fabric, and a second spunbond nonwoven fabric), but also to the case where layers B and D are made of nonwoven fabrics having a predetermined breathability.

[0036] The conductive nonwoven fabric can have a conductive substance attached to or mixed into at least one of the first spunbond nonwoven fabric, the meltblown nonwoven fabric, and the second spunbond nonwoven fabric, for example.

[0037] A preferred embodiment of the nonwoven fabric will be described later. Examples of conductive substances include conductive polymers, carbon black, graphite, acetylene black, metals, soft magnetic metals, and stearic acid monoglyceride, and from the viewpoint of electromagnetic wave absorption performance, it is preferable to include a conductive polymer.

[0038] The conductive substance may be attached in such a manner that at least a portion of the conductive substance is attached to at least a portion of the area of ​​the fibers that make up the nonwoven fabric. The conductive substance may be attached in any of the following ways: the conductive polymer is attached only to the fibers on the surface portion of the nonwoven fabric (i.e., the portion visible from the outside of the nonwoven fabric; the same applies below); the conductive polymer is attached only to the fibers inside the nonwoven fabric; or the conductive polymer is attached to both the fibers on the surface portion of the nonwoven fabric and the fibers inside the nonwoven fabric.

[0039] The type of conductive polymer is not particularly limited, but examples include poly3,4-ethylenedioxythiophene (hereinafter also referred to as "PEDOT"), PEDOT-PSS in which PEDOT is doped with poly4-styrenesulfanate (hereinafter also referred to as "PSS"), polypyrrole, polythiophene, polyacetylene, polyaniline, etc. Among the above, from the viewpoint of electromagnetic wave absorption performance, the conductive polymer preferably contains at least one of PEDOT and PEDOT-PSS, and more preferably contains PEDOT-PSS. As the PEDOT-PSS, for example, the PEDOT-PSS described in WO 2013 / 073673 can be used.

[0040] There are no particular limitations on the method for producing a conductive nonwoven fabric having a conductive substance attached thereto, but the production method may include, for example, an attachment step in which a liquid containing a conductive substance (more preferably a conductive polymer) is applied to a nonwoven fabric to attach the conductive substance to the nonwoven fabric.

[0041] The coating method is not particularly limited, and known coating methods such as immersion coating (e.g., dip coating), spray coating (e.g., spray coating), rotation coating (e.g., spin coating), slit coating, curtain coating, gravure coating, and flexo coating can be used.

[0042] The method for producing the conductive nonwoven fabric may further include a drying step of drying the liquid containing the conductive material applied to the nonwoven fabric. The drying method in the drying step is not particularly limited, and can be performed by a known method such as drying by air blowing, drying by heat, or a combination thereof. The method for producing the conductive nonwoven fabric may be such that the coating step and the drying step are repeated multiple times.

[0043] The liquid containing the conductive substance may be either a solution or a dispersion in which the conductive substance is dissolved, but from the viewpoint of attaching the conductive substance to the nonwoven fabric with high uniformity, a solution in which the conductive substance is dissolved is preferred. Examples of the solvent in the liquid containing the conductive material include water, ethanol, propyl alcohol, etc. The solvent may be used alone or in combination of two or more. The liquid containing the conductive material may contain a binder resin to improve the fixation and stability of the conductive material on the nonwoven fabric surface. Examples of binder resins include, but are not limited to, olefin resins, polyester resins, acrylic resins, polyurethane resins, polyvinyl acetate resins, vinylidene chloride resins, vinyl chloride resins, polyamide resins, polyimide resins, styrene resins, fluororesins, silicone resins, epoxy resins, phenolic resins, aliphatic ester resins, and aliphatic ether resin compounds. The content of the conductive substance in the entire liquid containing the conductive substance is preferably 0.1 mass % to 10.0 mass %, more preferably 0.2 mass % to 5.0 mass %.

[0044] For details of the attachment step, the description in International Publication No. 2013 / 073673 can be referred to as appropriate.

[0045] The sound-absorbing material according to the present disclosure will be described in detail below, layer by layer.

[0046] <Layer A> Layer A has three or more layers of nonwoven fabric including a first spunbond nonwoven fabric, a meltblown nonwoven fabric, and a second spunbond nonwoven fabric, and has an air permeability of 48 cc / cm 2 / sec or less.

[0047] ·Layer A: Layer configuration The layer structure of Layer A may be any structure having three or more layers of nonwoven fabric including a first spunbond nonwoven fabric, a meltblown nonwoven fabric, and a second spunbond nonwoven fabric, and the layer structure such as the stacking order is not particularly limited. Spunbond nonwoven fabrics have sufficient surface strength, making it unlikely that the front or back surface of the nonwoven fabric will be torn by sharp objects. This makes it easier to suppress the reduction in sound absorption rate that would otherwise be caused by tearing the front or back surface of the nonwoven fabric, as well as the strength, attachment strength, water resistance, etc. of the sound-absorbing material itself.

[0048] From the viewpoint of improving sound absorption properties over a wide frequency range and further reducing the variation in sound absorption coefficient over that frequency range, the layer structure of Layer A preferably has four or more layers of nonwoven fabric, with a third spunbond nonwoven fabric further laminated on the outermost surface on the sound incident side.

[0049] Examples of the layer structure of Layer A include the following (1) to (4), but the first embodiment is not limited to these. (1) Layer A (also referred to as SMS layer configuration) has three layers of nonwoven fabric including a first spunbond nonwoven fabric, a meltblown nonwoven fabric, and a second spunbond nonwoven fabric, in that order from the sound incident side in the layer thickness direction. (2) Layer A (also referred to as SSM layer configuration) has three layers of nonwoven fabric including a first spunbond nonwoven fabric, a second spunbond nonwoven fabric, and a meltblown nonwoven fabric, in that order from the sound incident side in the layer thickness direction. (3) Layer A (also referred to as MSS layer configuration) having three layers of nonwoven fabric including a meltblown nonwoven fabric, a first spunbond nonwoven fabric, and a second spunbond nonwoven fabric, in that order from the sound incident surface side to the layer thickness direction. (4) Layer A (also referred to as SSMS layer configuration) having three layers of nonwoven fabric including a third spunbond nonwoven fabric, a first spunbond nonwoven fabric, a meltblown nonwoven fabric, and a second spunbond nonwoven fabric, in this order from the sound incident surface side in the layer thickness direction. (5) Layer A (also referred to as SMSS layer configuration) having three layers of nonwoven fabric including a first spunbond nonwoven fabric, a meltblown nonwoven fabric, a second spunbond nonwoven fabric, and a third spunbond nonwoven fabric, in that order from the sound incident surface side to the layer thickness direction.

[0050] The layer A and the layer C may have the same or different air permeabilities. Layer A and layer C may have the same thickness or different thicknesses. Layer A and Layer C may be made of the same or different materials. Layer A and Layer C being made of different materials means that the component compositions contained in the materials are different. For example, Layer A and Layer C are considered to be made of different materials when they differ in at least one of the following: the type and amount of resin contained in the material, the presence or absence of a filler, and, if a filler is contained, the type and amount of filler.

[0051] From the viewpoints of improving sound absorption over a wide frequency range and further reducing the variation in sound absorption coefficient in the frequency range, it is preferable that Layer A and Layer C have the same layer structure. The same layer structure means that the stacking order of three or more layers of nonwoven fabric including a first spunbond nonwoven fabric, a meltblown nonwoven fabric, and a second spunbond nonwoven fabric (four or more layers of nonwoven fabric if a third spunbond nonwoven fabric is included), the basis weight, breathability, material, thickness, etc. of each nonwoven fabric are the same.

[0052] In one embodiment, layer A has four or more layers of nonwoven fabric, with a third spunbond nonwoven fabric further laminated on the outermost surface on the sound incident side, and has an air permeability of 12 cc / cm 2 / sec or more 48cc / cm 2 / sec or less, the average fiber diameter of the fibers contained in the third spunbond nonwoven fabric is larger than the average fiber diameters of the fibers contained in the first spunbond nonwoven fabric and the second spunbond nonwoven fabric, and the average fiber diameter of the fibers contained in the third spunbond nonwoven fabric is preferably 20 μm or more and 50 μm or less. When Layer A has the above configuration, the sound absorption property is improved over a wide frequency range and the variation in the sound absorption coefficient in the frequency range is further reduced.

[0053] Layer A: Type of nonwoven fabric The first, second, and third spunbond nonwoven fabrics may be the same or different. The term "spunbond nonwoven fabrics" refers to nonwoven fabrics with the same component composition. For example, when comparing a first spunbond nonwoven fabric with a second spunbond nonwoven fabric, if the type and amount of resin contained in the material, the basis weight, the fiber diameter of the fibers contained in the nonwoven fabric, etc., the first spunbond nonwoven fabric and the second spunbond nonwoven fabric are considered to be the same.

[0054] Layer A may contain nonwoven fabrics other than spunbonded nonwoven fabrics and meltblown nonwoven fabrics (hereinafter also referred to as "other nonwoven fabrics"). Examples of other nonwoven fabrics include needle-punched nonwoven fabrics, thermal-bonded nonwoven fabrics, chemical-bonded nonwoven fabrics, stitch-bonded nonwoven fabrics, and spunlaced nonwoven fabrics.

[0055] The nonwoven fabric may be a long-fiber nonwoven fabric, a short-fiber nonwoven fabric, or a mixture of both. The fibers contained in the nonwoven fabric may be single fibers, side-by-side or core-sheath composite fibers, or crimped fibers. In the case of single fibers, they may contain multiple resins. Furthermore, the cross-sectional shape of the fibers may be circular or irregular, such as V-shaped, cross-shaped, or T-shaped. The nonwoven fabric may be configured to contain a plurality of fibers having different average fiber diameters. The nonwoven fabric may be composed of a plurality of fibers having different average fiber lengths. The nonwoven fabric may be composed of a plurality of fibers having different average fiber diameters and average fiber lengths.

[0056] The fibers contained in the nonwoven fabric may contain a thermoplastic resin. Examples of the thermoplastic resin include, but are not limited to, homopolymers or copolymers of α-olefins such as ethylene, propylene, 1-butene, 1-pentene, 1-hexene, 1-octene, 3-methyl-1-butene, 3-methyl-1-pentene, 3-ethyl-1-pentene, 4-methyl-1-pentene, and 4-methyl-1-hexene; polyester resins such as polyethylene terephthalate (PET), polybutylene terephthalate, polyethylene naphthalate, and polyhexamethylene terephthalate; polyamides such as nylon-6, nylon-66, and polymethaxylene adipamide; polyvinyl chloride, polyimide, ethylene-vinyl acetate copolymer; polyacrylonitrile; polycarbonate; polystyrene; ionomers; and hyperbranched polyolefins. The thermoplastic resin may consist of one type or a mixture of two or more types.

[0057] Examples of α-olefin homopolymers or copolymers include ethylene-based polymers such as ethylene-propylene random copolymers, high-pressure low-density polyethylene, linear low-density polyethylene (LLDPE), high-density polyethylene, and ethylene-1-butene random copolymers; propylene-based polymers (including biomass-derived propylene-based polymers); poly-1-butene; and poly-4-methyl-1-pentene.

[0058] The thermoplastic resin preferably contains at least one selected from the group consisting of high-pressure low-density polyethylene, linear low-density polyethylene (LLDPE), high-density polyethylene, propylene-based polymer, polyethylene terephthalate, and polyamide. From the viewpoints of further improving sound absorption properties over a wide frequency range and further reducing variations in sound absorption coefficient within the frequency range, the thermoplastic resin preferably contains a propylene-based polymer. In other words, the nonwoven fabric preferably contains a propylene-based polymer from the viewpoints of further improving sound absorption properties over a wide frequency range and further reducing the variation in sound absorption coefficient in the frequency range, facilitating physical bonding of Layers A to D by ultrasonic fusion or radiant heat, and being lightweight as a resin.

[0059] Examples of propylene polymers include propylene homopolymers and propylene random copolymers, which are copolymers of propylene as a main component and one or more α-olefins as secondary components, and among these, propylene homopolymers are preferred. In the propylene random copolymer, the content of structural units derived from α-olefins is preferably 1 mol % to 10 mol %, more preferably 1 mol % to 5 mol %, of the total.

[0060] The α-olefin used in copolymerization for the propylene random copolymer is preferably an α-olefin having 2 or more carbon atoms (excluding propylene), more preferably an α-olefin having 2 or 4 to 8 carbon atoms. Specific preferred α-olefins include ethylene, 1-butene, 1-pentene, 1-hexene, 1-octene, 3-methyl-1-butene, 3-methyl-1-pentene, 3-ethyl-1-pentene, 4-methyl-1-pentene, and 4-methyl-1-hexene.

[0061] The propylene-based polymer may be a biomass-derived propylene-based polymer. The term "biomass-derived propylene polymer" refers to a propylene polymer (A) produced from raw material monomers containing biomass-derived propylene. Since the biomass-derived propylene polymer is a carbon-neutral material, it can reduce the environmental impact during the production of nonwoven fabric laminates. The biomass-derived propylene-containing monomer used as the raw material for the biomass-derived propylene-based polymer can be obtained by cracking biomass naphtha or synthesizing it from biomass-derived ethylene. The biomass-derived propylene-based polymer can be obtained by polymerizing the biomass-derived propylene-containing monomer synthesized in this manner using a method similar to that used in the case of using petroleum-derived propylene. A propylene-based polymer synthesized using a bio-derived propylene-containing monomer as a raw material is a biomass-derived propylene-based polymer. The content of the bio-derived propylene-based polymer in the raw material monomer is more than 0 mass% relative to the total amount of the raw material monomer, and may be 100 mass% or less. The monomers that are raw materials for biomass-derived propylene-based polymers may further contain, in addition to bio-derived propylene, propylene derived from fossil fuels such as petroleum, and / or α-olefins other than ethylene and propylene (1-butene, 1-hexene, etc.). Biomass-derived propylene polymers can also be obtained by polymerizing propylene obtained by the synthesis of methanol-to-olefins (MTO) or methanol-to-propylene (MTP) using gas generated by pyrolysis of empty fruit bunches (EFB) such as coconut shells. Furthermore, biomass-derived propylene polymers can also be obtained by polymerizing propylene obtained by dehydrating isopropanol produced by fermentation of biomass raw materials mainly consisting of inedible plants such as sorghum. The content of radioactive carbon (C14) in the raw material monomers such as propylene is P C14 In this case, the content of biomass-derived carbon in the raw material, Pbio (%), can be calculated using the following formula: Formula (2): Pbio(%)=P C14 / 105.5×100 That is, if all the raw materials for a propylene-based polymer are biomass-derived, the content of biomass-derived carbon will theoretically be 100%. Therefore, the biomass ratio of a biomass-derived propylene-based polymer will be 100%. Since fossil fuel-derived raw materials contain almost no C14, the content of biomass-derived carbon in a propylene-based polymer produced only from fossil fuel-derived raw materials will be 0%, and the biomass ratio of a fossil fuel-derived propylene-based polymer will be 0%. "Biomass content" indicates the content of carbon derived from biomass and is calculated by measuring radioactive carbon (C14). Carbon dioxide in the atmosphere contains a certain proportion of C14 (for example, approximately 105.5 pMC). Therefore, it is known that the C14 content in plants (such as corn) that grow by absorbing carbon dioxide from the atmosphere is also approximately 105.5 pMC. It is also known that fossil fuels contain almost no C14. Therefore, the content of biomass-derived carbon in the raw material can be calculated by measuring the proportion of C14 contained in the total carbon atoms in the propylene-based polymer. The term "recycled polymer" includes polymers obtained by recycling waste polymer products, and can be produced, for example, by the method described in German Patent Application Publication No. 102019127827. The recycled polymer may contain a marker that identifies it as having been obtained through recycling.

[0062] The melting point (Tm) of the propylene polymer is preferably 155° C. or higher, and more preferably 157° C. to 165° C. In the first embodiment, the melting point can be measured by a known method using differential scanning calorimetry (DSC).

[0063] The fibers contained in the nonwoven fabric constituting Layer A preferably contain 93.0% to 100% by mass, and more preferably 94.0% to 99.5% by mass, of a thermoplastic resin relative to the total mass of the nonwoven fabric. The fibers contained in the nonwoven fabric according to the present disclosure preferably contain 70.0% to 100% by mass, and more preferably 90.0% to 99.5% by mass, of a propylene-based polymer relative to the total mass of the nonwoven fabric.

[0064] The fibers contained in the nonwoven fabric constituting Layer A may contain commonly used additives as needed, such as antistatic agents, anti-static agents, absorbent particles, nanoparticles, ion exchange resins, deodorants, fragrances, adhesives, surface modifiers, biocides, antibacterial agents, antiviral agents, flame retardants, stabilizers, antioxidants, weathering stabilizers, heat stabilizers, light stabilizers, anti-fogging agents, lubricants, conductive materials, dyes, pigments, natural oils, synthetic oils, and waxes.

[0065] The nonwoven fabric constituting Layer A can be produced using a known nonwoven fabric molding machine. For example, a spunbond nonwoven fabric can be produced by melting a thermoplastic resin as a raw material using an extruder, discharging the molten composition from multiple spinnerets, cooling and stretching the fibrous resin as necessary, depositing it on a collecting surface, and then heating and pressurizing it with an embossing roll. Furthermore, a meltblown nonwoven fabric can be produced by melting a thermoplastic resin as a raw material, discharging it from a spinning nozzle, and pulling it with high-temperature, high-pressure gas to produce ultrafine fibers, which are then collected and deposited on a collector such as a perforated belt or perforated drum.

[0066] Layer A: Air permeability The air permeability of layer A is 48cc / cm 2 / sec or less. Furthermore, in order to exhibit excellent sound absorption properties over a wide frequency range and reduce the variation in sound absorption coefficient, the air permeability is 10 cc / cm 2 / sec or more 42cc / cm 2 / sec or less, and 11cc / cm 2 / sec or more 35cc / cm 2 / sec or less is more preferable, and 12cc / cm 2 / sec or more 32cc / cm 2 From the viewpoint of manufacturing, the air permeability of the layer A is more preferably 1 cc / cm or less. 2 / sec or more is preferable, and 3cc / cm 2 / sec or more is more preferable, and 10cc / cm 2 / sec or more is more preferable, and 12cc / cm 2 / sec or more is particularly preferred.

[0067] The breathability of Layer A can be controlled by adjusting, for example, the type of nonwoven fabric, the layer thickness, basis weight, fiber diameter, etc.

[0068] Layer A: Average fiber diameter In order to improve sound absorption properties over a wide frequency range and further reduce variation in the sound absorption coefficient over that frequency range, the average fiber diameter of the fibers contained in the nonwoven fabric constituting Layer A is preferably small (i.e., thin fibers), more specifically, 10 μm to 100 μm, and the average fiber diameter on the sound-incident surface (hereinafter also referred to as the "surface average fiber diameter") is more preferably 20 μm to 100 μm, and even more preferably 30 μm to 50 μm. If the average fiber diameter is equal to or greater than the lower limit, the mechanical properties of the laminate are reduced, and reduction in laminate thickness during compression processing is suppressed.

[0069] When at least one of Layers B and D contains a nonwoven fabric, the average fiber diameter of Layer A is preferably smaller than the average fiber diameter of the fibers constituting the nonwoven fabric of these layers.

[0070] The average fiber diameter of the fibers contained in the first spunbond nonwoven fabric, the second spunbond nonwoven fabric, and the third spunbond nonwoven fabric is not particularly limited, but from the viewpoint of improving sound absorption properties over a wide frequency range and further reducing the variation in sound absorption coefficient in the frequency range, it is preferable that the average fiber diameter be larger than the average fiber diameter of the fibers contained in the meltblown nonwoven fabric.

[0071] The average fiber diameter of the fibers constituting the first and second spunbond nonwoven fabrics is preferably 8 μm or more and 30 μm or less, and more preferably 8 μm or more and 25 μm or less, from the viewpoint of further reducing the variation in sound absorption coefficient over a wide frequency range.

[0072] When at least one of Layers B and D contains a nonwoven fabric, the average fiber diameter of the fibers constituting the first and second spunbond nonwoven fabrics of Layer A is preferably smaller than the average fiber diameter of the fibers constituting the nonwoven fabrics of these layers.

[0073] The average fiber diameter (surface average fiber diameter) of the fibers contained in the third spunbond nonwoven fabric of Layer A is preferably relatively large from the viewpoint of sandblasting resistance (abrasion resistance), and is preferably 20 μm or more and 100 μm or less. The average fiber diameter of the fibers constituting the meltblown nonwoven fabric is preferably 0.5 μm or more, or 1 μm or more and 4 μm or less, from the viewpoint of improving sound absorption properties over a wide frequency range and further reducing the variation in sound absorption coefficient in the frequency range.

[0074] The method for setting the average fiber diameter of the fibers within the above range is not particularly limited, but for example, the average fiber diameter can be controlled by setting the embossing roll temperature to a range of 140°C to 170°C and the mirror roll temperature to a range of 140°C to 170°C, and then performing embossing (e.g., thermocompression bonding) to set the fusion area ratio to 15% to 30%, thereby promoting fusion between fibers in non-embossed areas and increasing the apparent fiber diameter. Alternatively, the average fiber diameter can be controlled by adjusting the fusion area ratio or embossing pattern during embossing.

[0075] Layer A: Weight The basis weight of Layer A is set to 30 g / m2 in order to exhibit excellent sound absorption properties over a wide frequency range and reduce the variation in sound absorption coefficient. 2 More than 230g / m 2 Preferably, it is 40 g / m or less. 2 More than 180g / m 2 More preferably, it is: The basis weight of the spunbond layer on the sound incident side of Layer A is 20 g / m2 from the viewpoint of maintaining sandblast resistance. 2 More than 200g / m 2 Preferably, it is 30 g / m or less. 2 More than 150g / m 2 More preferably, it is 90 g / m or less. 2 More than 150g / m 2 It is even more preferable that: The basis weight can be controlled by adjusting, for example, the layer thickness, the fiber diameter, and the like.

[0076] Layer A: Thickness The thickness of Layer A is preferably 0.1 mm or more and 1.5 mm or less, or 0.3 mm or more and 1.0 mm or less.

[0077] <Layer B> Layer B has an air permeability of 20cc / cm 2 / sec or more 4500cc / cm 2 Layer B may be a single layer or a laminate of two or more layers.

[0078] The material of Layer B is not particularly limited as long as it is a material or foam whose air permeability falls within the above range. Examples of the material for Layer B include sheet-like materials such as nonwoven fabric, a resin molded body having a three-dimensional mesh structure, porous film, paper, woven fabric, knitted fabric, felt, and inorganic fiber.

[0079] ·Layer B: Non-woven fabric The nonwoven fabric may be a long fiber nonwoven fabric, a short fiber nonwoven fabric, or a mixed fiber nonwoven fabric.

[0080] The fibers contained in the nonwoven fabric may be single fibers, composite fibers such as side-by-side or core-sheath fibers, or crimped fibers. Single fibers may contain multiple resins. The cross-sectional shape of the fibers may be round or irregular, such as V-shaped, cross-shaped, or T-shaped.

[0081] The nonwoven fabric may be configured to contain a plurality of fibers having different average fiber diameters. The nonwoven fabric may be composed of a plurality of fibers having different average fiber lengths. The nonwoven fabric may be composed of a plurality of fibers having different average fiber diameters and average fiber lengths.

[0082] The fibers contained in the nonwoven fabric preferably contain a thermoplastic resin. Examples of the thermoplastic resin include the thermoplastic resins exemplified above for Layer A. The thermoplastic resin may consist of one type or a mixture of two or more types.

[0083] From the viewpoint of improving sound absorption properties over a wide frequency range and further reducing the variation in sound absorption coefficient in the frequency range, the thermoplastic resin more preferably contains at least one of a polyester-based resin and an olefin-based polymer, preferably contains a polyester-based resin, further preferably contains both a polyester-based resin and an olefin-based polymer, and particularly preferably contains both a polyester-based resin and a propylene-based polymer.

[0084] The polyester resin includes, for example, a polyester homopolymer resin and a polyester copolymer resin. Polyester resins (particularly polyester resins containing a polyester copolymer resin and various low-melting binder resins such as acrylic resins, urethane resins, polyamide resins, and olefin resins) generally tend to have low melting points, and therefore, including a polyester resin is preferable because it facilitates bonding between the layers regardless of the type of resin that constitutes Layer A and Layer C.

[0085] The olefin polymer preferably contains at least one of a propylene polymer and an ethylene polymer. When the nonwoven fabric constituting at least one of Layer B and Layer D contains an olefin-based polymer, it becomes easier to bond the resulting layers together after forming Layer A, Layer B, Layer C, and Layer D, respectively. In particular, when the nonwoven fabric constituting at least one of Layer A and Layer C contains a propylene-based polymer, it is preferable that the nonwoven fabric constituting at least one of Layer B and Layer D contains a propylene-based polymer, since this facilitates bonding of Layer A and Layer C to the highly breathable layers, Layer B and Layer D.

[0086] The fibers constituting Layer B may be, for example, made solely of polyester resin (more preferably polyethylene terephthalate resin) fibers, or may further contain propylene polymer fibers. By including fibers of a polyester resin (more preferably a polyethylene terephthalate resin) and fibers of a propylene polymer, sound absorption is more likely to be improved over a wide frequency range, and the variation in sound absorption coefficient in the frequency range is more likely to be reduced. In addition, the bulkiness can be easily adjusted, which allows the air permeability of Layer B to be increased to 20 cc / cm. 2 / sec or more 4500cc / cm 2 This is preferable because it is easy to adjust the range to within 1 / sec.

[0087] When a nonwoven fabric layer is used as Layer B, a nonwoven fabric made of short fibers of polyester resin, a nonwoven fabric containing both short fibers of polyester resin and short fibers of propylene polymer, etc. can be used. The polyester resin staple fibers and the propylene polymer staple fibers may be produced by a known melt spinning method, or commercially available products may be used. The short fibers of polyester resin may have an average fiber length in the range of 10 mm to 100 mm and an average fiber diameter in the range of 10 μm to 70 μm, for example. The short fibers of the propylene polymer may have an average fiber length in the range of 10 mm to 100 mm and an average fiber diameter in the range of 10 μm to 50 μm, for example.

[0088] From the viewpoint of further improving the sound absorption coefficient, the ratio of polyester resin staple fibers to propylene polymer staple fibers in the entire nonwoven fabric constituting Layer B is preferably in the range of 99:1 to 5:95 by mass, more preferably 95:5 to 10:90, and even more preferably 80:20 to 20:80, of polyester resin staple fibers:propylene polymer staple fibers.

[0089] When a polyethylene terephthalate resin is used as the polyester resin, the polyethylene terephthalate resin may be a copolymer of a polyhydric alcohol such as ethylene glycol and a dibasic acid such as terephthalic acid. Examples of such polyethylene terephthalate resins include polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polyethylene naphthalate (PEN), polybutylene naphthalate (PBN), polyethylene isophthalate (PEI), polybutylene isophthalate (PBI), polyhexamethylene terephthalate (PHT), polyhexamethylene isophthalate (PHI), and polyhexamethylene naphthalate (PHN).

[0090] The propylene polymer may be a homopolymer of propylene or a copolymer of propylene with another α-olefin copolymerizable with propylene. Examples of the α-olefin include α-olefins having 2 or more carbon atoms, preferably 2 to 8 carbon atoms, such as ethylene, 1-butene, 1-pentene, 1-hexene, 1-octene, and 4-methyl-1-pentene. When the propylene polymer is a copolymer of propylene and an α-olefin, it may be a copolymer of one or more α-olefins selected from the α-olefins. The propylene polymer may have a melt flow rate (MFR: ASTM D-1238, 230°C, 2160 g load) in the range of, for example, 1 g / min to 500 g / min.

[0091] In one embodiment, the nonwoven fabric is preferably composed of fibers composed of two or more components, namely, a low-melting-point resin and a high-melting-point resin. Specific examples include composite fibers of low-melting-point polyester resin / high-melting-point polyester resin (preferably, core-sheath or side-by-side composite fibers). By including fibers of high-melting-point polyester resin in the nonwoven fabric, the shape retention of the nonwoven fabric can be controlled. Furthermore, by including fibers of low-melting-point polyester resin and exposing them on the fiber surface, it becomes easier to bond the resulting layers together after forming each of Layers A, B, C, and D.

[0092] The melting point of the low-melting polyester resin is preferably not more than 130, more preferably not more than 120. There is no particular lower limit, but it may be, for example, 70° C. or higher. The melting point of the high-melting polyester resin is not particularly limited as long as it is higher than the melting point of the low-melting polyester resin, and may be, for example, 200°C or higher, or 220°C or higher. This allows for control of the shape retention of the nonwoven fabric of Layer B. This also results in excellent shape retention after forming Layer A, Layer B, Layer C, and Layer D and then subjecting them to heating, stretching, and compression processing.

[0093] Binder fiber The fibers contained in the nonwoven fabric constituting Layer B may further contain binder fibers from the viewpoint of bonding between the fibers constituting the nonwoven fabric and between the layers, and from the viewpoint of controlling the shape retention of Layer B. The binder fibers are fibers that provide binding between the fibers constituting Layer B and between the layers.

[0094] Examples of binder fibers include short fibers of propylene polymers, fibers of low-melting ethylene polymers, fibers of low-melting polyester resins, low-melting hyperbranched polyolefin fibers (for example, SWP (registered trademark) manufactured by Mitsui Chemicals, Inc.), acrylic fibers, composite fibers of low-melting polyester resins / high-melting polyester resins (preferably composite fibers of a core-sheath structure or a side-by-side structure), composite fibers of propylene polymers / ethylene polymers (preferably composite fibers of a core-sheath structure or a side-by-side structure), and composite fibers of ethylene polymers / polyester resins (preferably composite fibers of a core-sheath structure or a side-by-side structure).

[0095] The resin constituting the binder fibers may be a synthetic product or a commercially available product, such as Melty 4080 (manufactured by Unitika Ltd.).

[0096] The binder fibers may be obtained, for example, by applying a solution containing a binder component (e.g., a fibrous emulsion) by spray coating or the like during the preparation of Layer B, and then heat-treating the coating film. In this case, the binder component preferably contains an emulsion of an acrylic resin (e.g., Boncoat AN-1170 manufactured by DIC Corporation). Other examples of the binder component include urethane resins, polyamide resins, and olefin resins.

[0097] In one embodiment, the polyester resin binder staple fiber may have a core made of polyethylene terephthalate and a sheath made of a binder component, such as a copolymer polyester made of acrylic, terephthalic acid or its ester-forming derivative, isophthalic acid or its ester-forming derivative, lower alcohol, or polyalkylene glycol or its monoether.

[0098] In one embodiment, the nonwoven fabric constituting Layer B can be obtained by, for example, mixing 1% by mass to 95% by mass (preferably 1% by mass to 60% by mass) of the propylene polymer staple fibers with 99% by mass to 5% by mass (preferably 40% by mass to 5% by mass) of polyester resin binder staple fibers (preferably polyethylene terephthalate resin staple fibers), forming a web using a fiber opener and a carding machine, laminating the resulting web in multiple layers using a cross-layer machine, and treating it with a hot air treatment machine set to a predetermined gap distance to fuse the polyester resin binder staple fibers and the propylene polymer staple fibers.

[0099] In one embodiment, the polyester resin binder staple fiber may have a core made of polyethylene terephthalate and a sheath made of a binder component, such as a copolymer polyester made of acrylic, terephthalic acid or its ester-forming derivative, isophthalic acid or its ester-forming derivative, lower alcohol, or polyalkylene glycol or its monoether.

[0100] The fibers contained in the nonwoven fabric constituting Layer B may contain commonly used additives as needed. Examples of the additives include various known additives such as antistatic agents, antistatic agents, absorbent particles, nanoparticles, ion exchange resins, deodorants, fragrances, adhesives, surface modifiers, biocides, antibacterial agents, antiviral agents, flame retardants, stabilizers, antioxidants, weathering stabilizers, heat stabilizers, light stabilizers, antifogging agents, lubricants, conductive materials, dyes, pigments, natural oils, synthetic oils, and waxes.

[0101] The method for producing the nonwoven fabric is not particularly limited, and known methods can be used, such as mechanically bonding fibers by needle punching or fusing fibers by heat treatment.

[0102] -Resin molding with a three-dimensional mesh structure Examples of resin molded articles having a three-dimensional network structure include resin molded articles obtained by molding a resin composition containing the above-mentioned thermoplastic resin into a three-dimensional network shape, and more preferably resin molded articles obtained by molding a resin composition containing either an ethylene-based polymer or a propylene-based polymer into a three-dimensional network shape. Note that the resin molded article having a three-dimensional network structure refers to a resin molded article having a three-dimensional network structure.

[0103] ·Perforated film Examples of porous films include microporous films and mesoporous films. Examples of porous films include resin porous films such as films made porous by stretching a resin containing a filler or a phase-separated polymer alloy, inorganic porous films such as porous cement films, and films with holes formed by processing such as needle punching. The breathability of the porous film can be controlled by adjusting, for example, the thickness, density, pore size, etc.

[0104] Inorganic fibers Examples of inorganic fibers include glass fibers and carbon fibers.

[0105] Foam Examples of foams include rubber foams, polyolefin foams (such as polyethylene foams and polypropylene foams), polyurethane foams, polystyrene foams, and acrylic copolymer foams.

[0106] The air permeability of the foam can be controlled by adjusting, for example, the thickness, density, closed cell ratio, and the like. The foam preferably has an open-cell structure from the viewpoint of increasing the air permeability of the highly breathable layer and from the viewpoint of increasing the sound absorbing properties of the sound absorbing material. The density of the foam is 9 kg / m 3 More than 200kg / m 3 It is preferable that the density is less than 10 kg / m 3 More than 200kg / m 3 More preferably, it is 20 kg / m or less. 3 Below Upper 200kg / m 3It is more preferable that the density of the foam is as follows: The density of the foam is measured in accordance with Method A (water displacement method) of ASTM D792. The closed cell ratio of the foam is preferably 0% or more and less than 60%, more preferably 0% or more and 55% or less, and even more preferably 0% or more and 50% or less. The closed cell ratio of the foam is measured in accordance with Method C of ASTM D2856. The average diameter of the cells in the foam is preferably 10 μm or more and 2000 μm or less, more preferably 300 μm or more and 2000 μm or less, and even more preferably 600 μm or more and 2000 μm or less.

[0107] Layer B: Breathability Layer B has an air permeability of 20cc / cm 2 / sec or more 4500cc / cm 2 / sec or less, and from the viewpoint of exhibiting superior sound absorption properties over a wide frequency range and further reducing the variation in sound absorption coefficient, 2 / sec or more, and 2 / sec or more is more preferable, and 3 / cm 2 It is more preferable that the layer has a viscosity of 1 / sec or more. The air permeability of layer B is set at 4500 cm from the viewpoint of strength, etc. 3 / cm 2 / sec or less, and 1000 cm 3 / cm 2 / sec or less is more preferable, and 600 cm 3 / cm 2 It is more preferable that the speed is equal to or less than 1 / sec.

[0108] The air permeability of Layer B can be controlled, for example, by adjusting the layer thickness and basis weight, or by using a nonwoven fabric as the material for Layer B and adjusting the fiber diameter, fiber length, and resin (preferably a polyester resin) contained in the fibers. It can also be controlled by adjusting the porosity and other factors through post-processing such as calendaring.

[0109] Layer B: Average fiber diameter The fiber diameter of the fibers contained in Layer B (hereinafter sometimes referred to as the "average fiber diameter of Layer B") is preferably 10 μm or more and 100 μm or less, 10 μm or more and 70 μm or less, 10 μm or more and 50 μm or less, 15 μm or more and 45 μm or less, or 20 μm or more and 40 μm or less, from the viewpoint of exhibiting excellent sound absorption properties over a wide frequency range and reducing the variation in the sound absorption coefficient.

[0110] The average fiber diameter of Layer B is calculated from all fibers contained in Layer B. That is, when Layer B is composed of a nonwoven fabric containing fibers of one type of thermoplastic resin, the "average fiber diameter of Layer B" refers to the average fiber diameter of the fibers of that one type of thermoplastic resin. When Layer B is composed of a nonwoven fabric containing fibers of two or more types of thermoplastic resin, the "average fiber diameter of Layer B" refers to the arithmetic mean value of the fiber diameters of all fibers containing a mixture of those two or more types of thermoplastic resin. When Layer B is composed of a nonwoven fabric containing multiple fibers with different fiber diameters, the "average fiber diameter of Layer B" refers to the arithmetic mean value of the fiber diameters of all fibers containing a mixture of those multiple fibers with different fiber diameters. The method for controlling the average fiber diameter of Layer B to fall within the desired range is not particularly limited. It can be controlled in the same way as the average fiber diameter of Layer A.

[0111] Layer B: Weight The basis weight of Layer B is set to 50 g / m from the viewpoint of improving sound absorption over a wide frequency range and further reducing the variation in sound absorption coefficient in the frequency range, and from the viewpoint of preventing a decrease in workability due to an increase in the weight of the sound-absorbing material. 2 More than 1500g / m 2 The basis weight of Layer B is preferably 60 g / m or less from the viewpoint of preventing a decrease in workability due to an increase in the weight of the sound-absorbing material and from the viewpoint of reducing the amount of carbon dioxide emitted. 2 More than 400g / m 2 More preferably, it is 70 g / m or less. 2 More than 300g / m 2 More preferably, it is 70 g / m or less. 2 More than 200g / m 2 It is particularly preferred that: The basis weight of Layer B can be controlled by adjusting, for example, the thickness of the layer, the fiber diameter, and the like.

[0112] Layer B: Thickness The thickness of Layer B is preferably 0.1 mm or more and 100.0 mm or less, more preferably 0.3 mm or more and 60.0 mm or less, and even more preferably 5.0 mm or more and 40.0 mm or less.

[0113] In one embodiment, from the viewpoint of improving sound absorption properties over a wide frequency range and further reducing the variation in sound absorption coefficient over the frequency range, Layer B may be a nonwoven fabric containing short fibers of a polyester resin (more preferably polyethylene terephthalate) and short fibers of a propylene polymer. In this case, the average fiber diameter of the short fibers of the polyester resin is preferably 10 μm or more and 100 μm or less, more preferably 10 μm or more and 70 μm or less, and even more preferably 10 μm or more and 50 μm or less.

[0114] In the above case, the ratio of the polyester resin staple fibers to the propylene polymer staple fibers (ester resin staple fibers:propylene polymer staple fibers) is preferably 99:1 or more and 5:95 or less, more preferably 95:5 or more and 10:90 or less, and even more preferably 80:20 or more and 20:80 or less, by mass, from the viewpoint of further improving sound absorption properties and improving hydrophobicity and drainage properties.

[0115] In the above case, for example, Layer B can be produced by mixing propylene-based polymer staple fibers with polyester-based resin staple fibers, passing the mixture through an opener and a carding machine to form a web, laminating the resulting web in multiple layers using a cross-layer machine, and treating it with a hot air treatment machine set to a predetermined gap distance, thereby producing a nonwoven fabric in which the polyester-based resin staple fibers and the propylene-based polymer staple fibers are fusion-bonded.

[0116] <Layer C> Layer C has three or more layers of nonwoven fabric including a first spunbond nonwoven fabric, a meltblown nonwoven fabric, and a second spunbond nonwoven fabric, and has an air permeability of 48 cc / cm 2 / sec or less. The preferred aspects of the layer structure, materials and properties of Layer C are the same as the preferred aspects of the layer structure, materials and properties of Layer A.

[0117] The layer structure, material and characteristics of Layer C may be the same as or different from the layer structure, material and characteristics of Layer A. However, from the viewpoint of further improving sound absorption properties over a wide frequency range and further reducing the variation in sound absorption coefficient in the frequency range, it is preferable that at least one of the layer structure and material be the same.

[0118] For example, the material of layer C is different from the material of layer A, meaning that the component compositions (layer structure, material, and properties resulting from these, etc.) contained in each layer are different. For example, if the types of resins constituting the fibers contained in the nonwoven fabric in Layer C and Layer A are different, Layer C and Layer A are considered to be made of different materials. For example, if Layer C and Layer A differ in the basis weight, breathability, or average fiber diameter of the fibers contained in the nonwoven fabric, the properties of Layer C and Layer A are considered to be different.

[0119] <Layer D> Layer D has an air permeability of 20cc / cm 2 / sec or more 4500cc / cm 2 / sec or less, a foam, or a backing air layer. Layer D may be a single layer or a laminate of two or more layers.

[0120] Layer D has an air permeability of 20 cc / cm from the viewpoint of further improving sound absorption over a wide frequency range and further reducing the variation in sound absorption coefficient in the frequency range. 2 / sec or more 4500cc / cm 2 / sec or less, foam, or back air layer, and the air permeability is 30cc / cm 2 / sec or more 4500cc / cm 2 Preferably, the layer or foam has a viscosity of 1 / sec or less.

[0121] The air permeability in layer D is 20cc / cm 2 / sec or more 4500cc / cm 2 A preferred embodiment of the layer and foam is that the air permeability in Layer B is 20 cc / cm 2 / sec or more 4500cc / cm 2 / sec or less layers and foams are similar to the preferred embodiments. The layer structure, material, and characteristics of Layer D may be the same as or different from the layer structure, material, and characteristics of Layer B. However, from the viewpoint of further improving sound absorption properties over a wide frequency range and further reducing the variation in sound absorption coefficient in the frequency range, it is preferable that at least one of the layer structure and material be the same.

[0122] For example, the material of layer D is different from the material of layer B, meaning that the component compositions contained in each layer are different. For example, Layer D and Layer B are considered to be made of different materials when the types of resin, foam, etc. that make up the layers are different (for example, in the case of a nonwoven fabric, the type of resin that makes up the fibers contained in the nonwoven fabric) or when Layer D is a back air layer. For example, if Layer D and Layer B differ in air permeability, basis weight of the fibers contained in each layer, or average fiber diameter, Layer D and Layer B are considered to have different properties.

[0123] Back air layer Layer D may be a backing air layer. The rear air space refers to the air gap between the surface of layer C opposite the sound incident surface and the installation surface where the sound absorbing material is installed. The installation surface may be a so-called reflective surface. When layer D is a backing air space, the sound-absorbing material also includes a support material for maintaining a gap from the opposite side of the sound-incident surface of layer C to the installation surface on which the sound-absorbing material is attached. As the support material, for example, known support materials such as metal or resin support rods, support frames, and substrates can be used.

[0124] When layer D is a backing air layer, sound absorption is more likely to be improved over a wide frequency range, and the variation in sound absorption coefficient is more likely to be reduced.

[0125] When Layer D is a backing air space, the bonding strength between the sound incident side and the support material is maintained by the materials and other properties of the other layers according to the present disclosure. In particular, when bonding the edge of the sound incident side to the support material, it is preferable that at least one of Layers A and C has a high tensile strength. For example, it is preferable that the tensile strength of at least one of Layers A and C is 50 N / 50 mm or more, or 60 N / 50 mm or more, regardless of the MD or CD direction. When Layer D is a rear air layer, it is preferable that the basis weight of Layer C and the average fiber diameter of the spunbond nonwoven fabric be within the above-mentioned ranges in order to maintain the bonding strength between the opposing surface of Layer C where sound is incident and the support material.

[0126] Furthermore, when Layer D is a backing air layer, from the viewpoint of the conformability and flexibility of the sound-absorbing material, it is preferable to use a spunbond nonwoven fabric or a spunbond nonwoven fabric containing a propylene-based polymer as the material for the other layers. Furthermore, since spunbond nonwoven fabrics have sufficient surface strength, the surface or back surface of the nonwoven fabric is unlikely to be torn by sharp objects, which makes it easier to suppress a decrease in sound absorption coefficient caused by tearing the surface or back surface of the nonwoven fabric, as well as the strength, attachment strength, water resistance, etc. of the sound-absorbing material itself. In particular, from the viewpoint of imparting sufficient surface strength, it is preferable to set the basis weight of at least one of Layers A and C and the average fiber diameter of the nonwoven fabric within the above-mentioned ranges.

[0127] The thickness of the rear air layer, i.e., the shortest distance of the gap from the opposite side of sound incidence to the installation surface, is not particularly limited, but can be, for example, 2 mm or more, 5 mm or more, 8 mm or more, or 10 mm or more, and 50 mm or less, 30 mm or less, or 20 mm or less, and is preferably 2 mm or more and 50 mm or less. The thickness of the rear air space is the arithmetic average of the shortest distances measured at any five points from the opposite side of the incident surface where sound enters layer C to the installation surface where the sound absorbing material is attached.

[0128] <Method of manufacturing sound-absorbing material> The method for producing the sound-absorbing material according to the present disclosure is not particularly limited, and known production methods can be applied. The method for manufacturing the sound-absorbing material according to the present disclosure may involve forming each layer separately and then laminating them, or may involve forming each layer sequentially while laminating them. For example, when producing a sound-absorbing material, the material may be produced by forming Layer A, Layer B, Layer C, and Layer D, respectively, and then laminating the resulting layers. Alternatively, for example, after forming Layer A, Layer B may be formed on Layer A, and Layers C and D may be formed sequentially in the same manner.

[0129] The method of bonding between layers of the sound-absorbing material can be selected appropriately depending on the material of the layers, but examples include bonding with an adhesive (e.g., hot melt adhesive, acrylic adhesive, urethane adhesive, polyamide adhesive, olefin adhesive, etc.), heat fusion (e.g., heat treatment, heat embossing, ultrasonic fusion, etc.), mechanical entanglement (e.g., needle punching, water jet, etc.), physical pressure bonding, and combinations of these.

[0130] In one embodiment, the sound-absorbing material according to the present disclosure may be manufactured by forming layers A, B, C, and D, respectively, and then joining the ends of each of the obtained layers by ultrasonic welding, preheating each layer by radiant heat or the like, and then physically pressing them together.

[0131] When heat fusion is used as the bonding method between the layers, the fusion temperature is not particularly limited as long as it is a temperature at which the layers can be fused together. However, from the viewpoint of preventing peeling at the fused portions, the fusion temperature is preferably 130°C or higher and 160°C or lower, and more preferably 140°C or higher and 155°C or lower.

[0132] When physical pressure bonding is used as the bonding method between the layers, the pressure is not particularly limited as long as it can bond the layers together, but is preferably 0.1 MPa to 5 MPa from the viewpoint of suppressing peeling of the bonded portions. The speed at which the bonded portions are formed is not particularly limited as long as it can bond the layers together, but is preferably 0.5 m / min to 30 m / min from the viewpoint of suppressing peeling of the bonded portions and improving work efficiency. Furthermore, the sound-absorbing material according to the present disclosure may be subjected to secondary processing such as printing, coating, heat treatment, and shaping, as long as the effect of the material is not impaired.

[0133] <Applications of sound-absorbing materials> The sound-absorbing material according to the present disclosure exhibits excellent sound absorption properties in the high-frequency range, i.e., a wide frequency range from 1000 Hz onwards, and has little variation in sound absorption coefficient, making it applicable to a variety of applications, including automobiles, electronic devices, buildings and homes.

[0134] The sound-absorbing material according to the present disclosure exhibits excellent sound absorption properties over a wide frequency range, reduces variation in sound absorption coefficient over that frequency range, and also has excellent scratch resistance (more specifically, abrasion resistance). Therefore, it can be suitably used as a sound-absorbing material for automobiles and railways, which require blocking of external sounds over a wide frequency range and scratch resistance, and more preferably as a sound-absorbing material for use around tires (e.g., wheel housings) and around floors (e.g., undercovers).

[0135] The sound-absorbing material according to the present disclosure also has water pressure resistance on the sound-incident surface, which prevents a decrease in sound absorption properties due to water exposure, making it suitable for use in areas where water resistance in addition to sound absorption is desirable, such as tires, sound-absorbing materials around floors, sound-absorbing materials for ships, and sound-absorbing materials for civil engineering and construction. [Example]

[0136] The present disclosure will be specifically explained below using examples, but the present invention is not limited to the following examples as long as it does not deviate from the gist of the present invention. The methods for measuring and evaluating the physical properties of the sound-absorbing materials obtained in the examples of the present disclosure are as follows.

[0137] (1) Metsuke The layer to be measured was peeled off from the sound-absorbing material. Next, 10 test pieces measuring 100 mm (fiber flow direction: MD) x 100 mm (direction perpendicular to the fiber flow direction (CD)) were taken from the nonwoven fabric. The test pieces were taken from 10 locations in the CD direction. Next, a top-pan electronic balance (manufactured by Kensei Kogyo Co., Ltd.) was used to measure the mass (g) of each test piece taken, and the arithmetic mean value of the mass of each test piece was calculated. The average value calculated above was then multiplied by 1 m. 2 The weight per unit area of ​​each nonwoven fabric is calculated as g / m 2 The total basis weight of the entire sound-absorbing material was calculated as the sum of the weights of each layer.

[0138] (2) Thickness The layer to be measured was peeled off from the sound-absorbing material, and 10 test pieces were taken. For each test piece, a load of 7g / cm was applied. 2 The thickness was measured at five points in the center and four corners using a thickness gauge. The average value of the 50 measured thicknesses was calculated and used as the thickness (mm) of each layer. The total thickness of the entire sound-absorbing material was calculated as the sum of the thicknesses of each layer.

[0139] (3) Breathability The layer to be measured was peeled off from the sound-absorbing material, and five test pieces were taken. The test pieces were measured for air permeability (amount of air that passed through the layer) at a pressure difference of 125 Pa using a Frazier-type testing machine in accordance with Method A (Fragile-type method) of JIS L1096 (2010), and the arithmetic mean value was taken as the air permeability. This measurement method was also applied to the measurement of the entire sound-absorbing material.

[0140] (4) Water pressure resistance Test pieces measuring 150mm (MD) x 150mm (CD) were taken from the skin of layer A to be measured in accordance with Method A (low water pressure method) specified in JIS L 1096, and the water pressure resistance of the test pieces was measured (using a water pressure resistance tester FX3000-4L manufactured by Swiss Textest). Measurements were taken at five points, and the arithmetic mean value was taken as the water pressure resistance.

[0141] (5) Abrasion resistance (sandblasting resistance) A 200mm (MD) x 25mm (CD) test piece was taken from Layer A to be measured and attached to a mount with double-sided tape (NW-25, manufactured by Nichiban). This mount was attached to the sample holder of a Gakushin-type abrasion fastness tester (RT-300S, manufactured by Daiei Scientific Instruments Co., Ltd.), and the number of times of abrasion using #180 sandpaper was measured under no load until loose pills of 1mm or larger were observed. This measurement was repeated five times, and the arithmetic mean value was taken as the abrasion resistance.

[0142] (6) Tensile strength: MD strength, CD strength (N / 50mm) A test piece measuring 200 mm (lengthwise) x 50 mm (widthwise) was taken from layer A to be measured, and measurements were taken at 5 points in the MD and 5 points in the CD using a tensile testing machine (Shimadzu Autograph AGS-J) with a chuck distance of 100 mm and a head speed of 100 mm / min. The average value was calculated to determine the tensile strength (N / 50 mm).

[0143] (7) Average fiber diameter For the spunbond nonwoven fabric, ten test pieces of 10 mm x 10 mm were taken, and using a microscope (Nikon Corporation, product name: ECLIPSE E400) at a magnification of 50x, the diameters of 30 randomly selected points on each test piece were read in μm units to the first decimal place, and the arithmetic mean value was taken as the average fiber diameter of the fibers contained in the spunbond nonwoven fabric. For nonwoven fabrics containing at least polyester resin fibers, 10 test pieces were sliced ​​to 10 mm x 10 mm x 5 mm and collected. Using a microscope (Nikon Corporation, product name: ECLIPSE E400) at 50x magnification, the diameters of 30 randomly selected points on each test piece were read in μm units to the first decimal place, and the average value was taken as the average fiber diameter. For meltblown nonwoven fabrics, the fiber diameters (μm) of 30 constituent fibers of the sampled specimen were measured at a magnification of 500x or 1000x using a scanning electron microscope (manufactured by Hitachi, Ltd., model name: SU3500), and the arithmetic mean value was taken as the average fiber diameter of the fibers contained in the meltblown nonwoven fabric.

[0144] [Example 1] <Preparation of Layer A> A propylene homopolymer with an MFR of 60 g / 10 min was melt-spun at 230°C by a conventional spunbond method using a spunbond nonwoven fabric molding machine with a spinneret of 0.6 mm in diameter, and the fibers obtained by spinning were deposited on a collecting surface to produce fibers with an average fiber diameter of 13 μm and a basis weight of 10 g / m. 2 A first spunbond nonwoven fabric was obtained. Next, a propylene homopolymer having an MFR of 400 g / 10 min was melted at 280°C using an extruder, and the resulting melt was extruded from a spinneret and heated air at 280°C was blown onto the first spunbond nonwoven fabric by a conventional meltblown method to deposit fibers having an average fiber diameter of 3 μm onto the first spunbond nonwoven fabric, resulting in a basis weight of 5 g / m. 2 A meltblown nonwoven fabric was formed. Next, fibers were deposited on the meltblown nonwoven fabric in the same manner as the spunbond nonwoven fabric, and the average fiber diameter was 13 μm and the basis weight was 10 g / m 2 A second spunbond nonwoven fabric was formed. Next, the laminate consisting of the first spunbond nonwoven fabric, meltblown nonwoven fabric, and second spunbond nonwoven fabric stacked in that order was integrated using a hot embossing roll with an imprint area ratio of 18%, with the embossing roll set at 145°C and the mirror roll at 150°C, to obtain a three-layer structure (hereinafter sometimes referred to as "SMS structure" or "PP-SMS") nonwoven fabric in which the first spunbond nonwoven fabric and the second spunbond nonwoven fabric were stacked on both the front and back sides of the meltblown nonwoven fabric. The basis weight of the resulting SMS structure nonwoven fabric was 25 g / m. 2 It was.

[0145] Next, a propylene homopolymer having an MFR of 60 g / 10 min was melt-spun at 230°C by a conventional spunbond method using a spunbond nonwoven fabric molding machine having a spinneret with a diameter of 1.3 mm, and the fibers obtained by spinning were deposited on the SMS structure nonwoven fabric to form a fiber having an average fiber diameter of 35 μm and a basis weight of 100 g / m 2 A third spunbond nonwoven fabric was formed. Next, the laminate of the SMS structure nonwoven fabric and the spunbond nonwoven fabric was integrated using a hot embossing roll (embossing pattern 0.9 mm square) with an imprint area ratio of 18%, with the embossing roll temperature set to 155°C and the mirror roll temperature set to 160°C, to obtain a four-layer structure nonwoven fabric (hereinafter sometimes referred to as "SSMS structure" or "PP-SSMS") in which the spunbond nonwoven fabric was laminated on top of the SMS structure nonwoven fabric as a skin material.

[0146] <Preparation of Layer B> Five parts by mass of propylene polymer staple fibers (manufactured by Ube Exsymo Co., Ltd., product name: UC Fiber, average fiber diameter 21 μm, average fiber length 51 mm), 65 parts by mass of polyethylene terephthalate resin staple fibers (average fiber diameter 35 μm, average fiber length 51 mm), and 30 parts by mass of polyethylene terephthalate resin binder staple fibers (manufactured by Unitika Ltd., product name: Melty 4080, average fiber diameter 14 μm, average fiber length 51 mm) were mixed together and formed into a web using a fiber spreader and a carding machine. The web was then multilayered using a cross-layer machine and treated with a hot air treatment machine set to a gap distance of approximately 20 mm to obtain a sheet-like nonwoven fabric molded product (referred to as "PET-1" in the tables) containing propylene polymer staple fibers and polyethylene terephthalate resin staple fibers.

[0147] <Preparation of Layer C> A propylene homopolymer with an MFR of 60 g / 10 min was melt-spun at 230°C by a conventional spunbond method using a spunbond nonwoven fabric molding machine with a spinneret of 0.6 mm in diameter, and the fibers obtained by spinning were deposited on a collecting surface to produce fibers with an average fiber diameter of 21 μm and a basis weight of 40 g / m. 2 A spunbond nonwoven fabric of 100g was obtained. Next, a propylene homopolymer having an MFR of 400 g / 10 min was melted at 280°C using an extruder, and the resulting melt was extruded from a spinneret while being blown with heated air at 280°C. This was done by a conventional meltblown method, depositing fibers having an average fiber diameter of 3 μm onto the spunbond nonwoven fabric, resulting in a basis weight of 25 g / m. 2 A meltblown nonwoven fabric was formed. Next, fibers were deposited on the meltblown nonwoven fabric in the same manner as in the spunbond nonwoven fabric, and the average fiber diameter was 21 μm and the basis weight was 20 g / m 2 A second spunbond nonwoven fabric was formed. Next, the laminate of the spunbond nonwoven fabric, meltblown nonwoven fabric, and spunbond nonwoven fabric was integrated using a hot embossing roll with an imprint area ratio of 12% and an embossing roll temperature set at 145°C and 150°C, respectively, to obtain an SMS structure nonwoven fabric. The basis weight of the SMS structure nonwoven fabric was 85 g / m 2 It was.

[0148] <Preparation of Layer D> In the same manner as in Layer B, a sheet-like nonwoven fabric molding having a thickness of about 20 mm was obtained.

[0149] <Production of sound-absorbing material> The size of each layer A to D was adjusted to 300 mm in the MD and 300 mm in the CD. A 250 mm square mark was previously marked on Layer A, 50 mm inward from each of the four edges. Layer A, Layer B, Layer C, and Layer D were laminated in this order, ensuring no deviation from the 300 mm square. These four layers were then fused at their edges with an ultrasonic sealer (Honda Electronics Co., Ltd., ultrasonic welder SONAC-37). The layers were sealed tightly with the ultrasonic sealer along the 250 mm square line marked on Layer A. The sealed area was 2 mm or wider. A 250 mm square sound-absorbing material was obtained by cutting along the sealed area.

[0150] [Examples 2 to 7] A sound-absorbing material was obtained in the same manner as in Example 1, except that the layer structures of Layer A and Layer C in Example 1 were set to the specifications shown in the table, and the physical properties of each layer, such as basis weight, air permeability, and thickness, were set to the specifications shown in the table.

[0151] [Example 8] Layers A to C were obtained in the same manner as in Example 1, except that the layer structure, basis weight, breathability, thickness, and other physical properties of each layer were set to the specifications shown in the table. Subsequently, Layer D, which was used as a back protective layer without forming a sheet-like nonwoven fabric molding, was laminated in this order with Layers A, B, and C, and fused with an ultrasonic sealer in the same manner as in Example 1 to obtain a laminate. This laminate was sampled into a circular shape with a diameter of 29 mm. The laminate was then placed at one end of a sound tube for measurement used in the "Evaluation of Sound Absorption Performance" described below, with a spacer installed as a support material between the side of Layer C of the circular laminate opposite the incident surface onto which sound is incident and a reflector, so that a back air layer with the thickness shown in Table 2-1 was formed, thereby obtaining a sound-absorbing material.

[0152] [Example 9] Layers A and C were obtained in the same manner as in Example 1, except that the layer structure, basis weight, breathability, thickness, and other physical properties of each layer were set to the specifications shown in the table. Next, 10 parts by mass of polyethylene terephthalate resin staple fibers (average fiber diameter 20 μm, average fiber length 51 mm), 45 parts by mass of polyethylene terephthalate resin staple fibers (average fiber diameter 25 μm, average fiber length 51 mm), and 45 parts by mass of polyethylene terephthalate resin staple fibers (average fiber diameter 35 μm, average fiber length 51 mm) were mixed, and 10 parts by weight of an acrylic emulsion binder (Boncoat AN-1170 manufactured by DIC Corporation, nonvolatile content 50%) was spray-coated as a binder component to form the binder fibers. The mixture was then treated with a hot air treatment machine set at a gap distance of approximately 40 mm to obtain a sheet-like nonwoven fabric molding (referred to as "PET-2" in the table) having a thickness of approximately 40 mm and containing polyethylene terephthalate resin staple fibers and the acrylic emulsion binder. Layer B was obtained in the same manner as in Example 1, except that the physical properties such as basis weight, breathability, and thickness were set to the specifications shown in the table. Then, Layer D, which was a sheet-like nonwoven fabric molding, was not formed as a back surface protective layer, and Layers A, B, and C were laminated in this order and fused with an ultrasonic sealer in the same manner as in Example 1 to obtain a laminate. This laminate was cut into a circular shape with a diameter of 29 mm. The laminate was then placed at one end of a sound tube for measurement used in the "Evaluation of sound absorption performance" described below, with a spacer provided as a support material between the side of Layer C of the circular laminate opposite the incident surface onto which sound is incident and a reflector so as to create a back air layer with the thickness shown in Table 2-1, thereby obtaining a sound-absorbing material.

[0153] [Example 10] Layers A and C were obtained in the same manner as in Example 1, except that the layer structure, basis weight, breathability, thickness, and other physical properties of each layer were set to the specifications shown in the table. Layer B was changed to Eptsealer EX100 (thickness 10 mm, referred to as "foam rubber" in the table) manufactured by Nitto Denko Corporation. Layers A, B, and C were laminated in this order without forming a sheet-like nonwoven fabric molding as Layer D, and then fused with an ultrasonic sealer in the same manner as in Example 1 to obtain a laminate. This laminate was cut into a circular shape with a diameter of 29 mm. The laminate was then placed at one end of a sound tube for measurement used in the "Evaluation of Sound Absorption Performance" section described below, with a spacer provided as a support material between the side of Layer C of the circular laminate opposite the sound incident surface onto which sound is incident and a reflector, so as to create a back air layer with the thickness shown in Table 2-1, thereby obtaining a sound-absorbing material.

[0154] [Example 11] The sound-absorbing material was obtained in the same manner as in Example 1, except that the physical properties of each layer, such as layer configuration, basis weight, breathability, and thickness, were set to the specifications shown in the table, and the material of Layer D was Hechimaron (product name) 350-1000 (a resin molded product having a three-dimensional mesh structure of a propylene-based polymer; referred to as "three-dimensional mesh-shaped resin molded product" in the table) manufactured by Shinko Nylon Co., Ltd.

[0155] [Example 12] Layers A to C were obtained in the same manner as in Example 1, except that the layer structure, basis weight, breathability, thickness, and other physical properties of each layer were set to the specifications shown in the table. Layer D was obtained in the same manner as in Example 1, except that 80 parts by mass of polyethylene terephthalate resin staple fibers (average fiber diameter 25 μm, average fiber length 51 mm) and 20 parts by mass of polyethylene terephthalate resin staple fibers (manufactured by Unitika Ltd., product name: Melty 4080, average fiber diameter 20 μm, average fiber length 51 mm) serving as binder fibers were mixed together, and a web was formed using a fiber spreader and a carding machine. The web was then multilayered using a cross-layer machine and treated using a hot air treatment machine with a gap distance set to approximately 20 mm to obtain a sheet-like nonwoven fabric molding having a thickness of approximately 20 mm containing propylene polymer staple fibers and polyethylene terephthalate resin staple fibers (referred to as "PET-3" in the tables). A sound absorbing material was obtained from the obtained Layers A to D in the same manner as in Example 1.

[0156] [Example 13] Layers A, C, and D were obtained in the same manner as in Example 1, except that the physical properties of each layer, such as the layer structure, basis weight, breathability, and thickness, were set to the specifications shown in the tables. Next, a sheet-like nonwoven fabric molding identical to PET-2 except for the thickness (referred to as "PET-4" in the tables) was used as Layer B, and a sound-absorbing material was obtained in the same manner as in Example 1.

[0157] [Examples 14 to 16] A sound-absorbing material was obtained in the same manner as in Example 1, except that the layer structure, basis weight, air permeability, thickness, and other physical properties of each layer were set to the specifications shown in the table.

[0158] [Example 17] After producing Layer A in Example 3, a 200 mm square sample was taken. A PEDOT-PSS solution containing a conductive material (solvent: a mixed solvent of water, ethanol, and propyl alcohol; mixed solvent / PEDOT-PSS=100 parts by mass / 3 parts by mass (including 2 parts by mass of binder resin component)) was applied to this sample from the 35 μm spunbond layer side of Layer A, and then the sample was left to dry in a room at 25°C for 24 hours to obtain a conductive nonwoven fabric. The basis weight after drying - basis weight before application was measured for 10 samples, and the result was 2 g / m 2The electromagnetic wave shielding properties (near-field measurement device) of this layer A were measured using an Anritsu MS46122B (VNA vector network analyzer). The sample size was 100 mm in the MD direction and 50 mm in the CD direction, and the average value of 10 measurements was obtained. As a result, the attenuation rate (Rtp value) at 6 GHz was 19.7. The attenuation rate (Rtp value) of layer A at 6 GHz before coating was 0.0. Using this obtained layer A, a sound-absorbing material was obtained in the same manner as in Example 3, except that the physical properties such as the layer structure, basis weight, air permeability, and thickness of the entire layer A were set to the specifications shown in the table.

[0159] [Comparative Example 1 and Comparative Example 6] A sound-absorbing material was obtained in the same manner as in Example 1, except that Layer A and Layer C were made of a melt-blown nonwoven fabric made of a propylene-based polymer (hereinafter, the structure of the layer may be referred to as "PP-MB"), which was produced by adjusting the heated air temperature, air flow rate, and the distance from the spinning nozzle to the collecting belt from the production conditions for the first layer of Example 1 described in WO 2018-182001.

[0160] [Comparative Examples 2 to 3] A sound-absorbing material was obtained in the same manner as in Example 1, except that the layer structure, basis weight, air permeability, thickness, and other physical properties of Layer A and Layer C were set to the specifications shown in the table.

[0161] Comparative Example 4 A sound-absorbing material was obtained in the same manner as in Example 1, except that the layer structure, basis weight, air permeability, thickness, and other physical properties of each layer were set to the specifications shown in the table. Layer A, Layer B, and Layer D were laminated in this order without forming Layer C, and fused with an ultrasonic sealer in the same manner as in Example 1 to obtain a sound-absorbing material.

[0162] Comparative Example 5 Layer A was obtained in the same manner as in Example 1, except that the basis weight structure, average fiber diameter of the spunbonded nonwoven fabric, breathability and thickness of the entire layer A were changed as shown in the table. The fabric was obtained in the same manner as in Example 1, except that Layer B was changed to Thinsulate (registered trademark) TC3403 (a blend of polyester fiber and polypropylene fiber, referred to as "PP-MB / PET" in the table) manufactured by 3M. Layers A and B were laminated in this order without forming Layers C and D, and fusion-bonded with an ultrasonic sealer in the same manner as in Example 1 to obtain a sound-absorbing material.

[0163] Comparative Example 7 Layers B and D are made of foamed urethane sheets (manufactured by INOAC, product name: ECS10, density: 22 kg / m 3 (referred to as "urethane foam" in the table). A sound-absorbing material was obtained in the same manner as in Comparative Example 1, except that the layer structure, basis weight, air permeability, thickness, and other physical properties of each layer were set to the specifications shown in the table.

[0164] [Comparative Example 8] Layers A and C had the same specifications as in Example 9. 60 parts by mass of propylene polymer staple fibers (manufactured by Ube Exsymo Co., Ltd., product name: UC Fiber, average fiber diameter 21 μm, average fiber length 51 mm) and 40 parts by mass of polyethylene terephthalate resin staple fibers (manufactured by Unitika Ltd., product name: Melty 4080, average fiber diameter 14 μm, average fiber length 51 mm) serving as binder fibers were mixed together, and a web was formed using a fiber spreader and a carding machine. The web was then multilayered using a cross-layer machine and treated using a hot air treatment machine with a gap distance set to approximately 50 mm, to obtain Layer B consisting of a sheet-like nonwoven fabric molded product (referred to as "PP-PET" in the Tables) having a thickness of approximately 50 mm and containing propylene polymer staple fibers and polyethylene terephthalate resin staple fibers. Next, Layer B was cut into a size of 250 mm (length) × 250 mm (width) × 50 mm (thickness). Next, Layers A and C were placed on both sides of the cut Layer B with spunbond nonwoven fabrics 4a and 4c on the outermost surfaces, and the peripheral edge of the skin material around Layer B was fused using an ultrasonic sealing machine (manufactured by Seidensha Electronics Co., Ltd., product name: J11430SA) under conditions of an output of 2.0 V, a pressure of 0.3 MPa, and a speed of 5 m / min to form a continuous seal portion with a width of 0.3 mm, thereby obtaining a sound-absorbing material in which Layer B was enclosed between Layers A and C. The excess portion around the outer periphery of the seal portion was cut off. Thereafter, without forming Layer D, Layer A, Layer B, and Layer C were laminated in this order, and fused with an ultrasonic sealer in the same manner as in Example 1 to obtain a sound-absorbing material.

[0165] The values ​​of the physical properties of the sound absorbing materials of each example measured by the above-mentioned measuring methods are summarized in each table. In the table, SB is an abbreviation for spunbond nonwoven fabric, and MB is an abbreviation for meltblown nonwoven fabric. In the table, the unit of air permeability is ccs, which is cc / cm 2 It is an abbreviation for / sec. In the table, in the item [SB average fiber diameter] for Layers A and C, when the average fiber diameters of the fibers contained in each of the multiple spunbond nonwoven fabrics stacked in the layer thickness direction from the incident surface side where sound is incident are different, the values ​​of the average fiber diameters of the fibers contained in the multiple spunbond nonwoven fabrics are listed in this order from the left.

[0166] In the table, the item [Basis Weight Configuration] in Layer A and Layer C indicates the basis weight value of each laminated nonwoven fabric. Specifically, for example, in Example 1, the layer configuration of Layer A is such that the third spunbond nonwoven fabric, the first spunbond nonwoven fabric, the meltblown nonwoven fabric, and the second spunbond nonwoven fabric are laminated in this order from the sound incident side in the layer thickness direction (PP-SSMS structure), and the basis weight value of each of these four types of nonwoven fabric is 100 (g / m 2 ), 10(g / m 2 ), 5(g / m 2 ) and 10(g / m 2 In Example 17, in addition to the basis weight of each laminated nonwoven fabric, the basis weight of the conductive material (2 g / m 2 ) is written on the left side. In the table, the item [basis weight] for Layer A and Layer C is the value measured for the entire layer of each of Layer A and Layer C.

[0167] [Sound absorption performance evaluation] -Sound absorption coefficient measurement The normal incident sound absorption coefficient of each sound absorbing material was measured as follows, and the results are shown in each table as "sound absorption coefficient." For each example of sound-absorbing material in which layer D was not a backing air space, a circular test piece with a diameter of 29 mm was taken from any part of the sound-absorbing material. Then, using an acoustic tube with an inner diameter of 29 mm, the normal incidence sound absorption coefficient was measured in accordance with ASTM E 1050 using a normal incidence sound absorption measuring device (Brüel & Kjær, TYPE 4206) when a plane sound wave with a frequency of 1000 Hz to 6300 Hz was perpendicularly incident on the test piece. For each example of sound-absorbing material in which layer D is a backing air space, the normal incidence sound absorption coefficient was measured in accordance with ASTM E 1050 using an acoustic tube in which the sound-absorbing material was provided, using a normal incidence sound absorption coefficient measuring device (Brüel & Kjær, TYPE 4206) when a plane sound wave with a frequency of 1000 Hz to 6300 Hz was perpendicularly incident on the test piece. From the obtained sound absorption coefficient curve from 1000 Hz to 6300 Hz, the normal incident sound absorption coefficient (hereinafter also simply referred to as "sound absorption coefficient") was determined for each of 1000 Hz, 1250 Hz, 1600 Hz, 2000 Hz, 2500 Hz, 3150 Hz, 4000 Hz, 5000 Hz and 6300 Hz.

[0168] -Evaluation of sound absorption coefficient variation The average sound absorption coefficient and the standard deviation of the sound absorption coefficient were calculated using the following formulas 1 and 2. Then, as an index 1 of the variation in the sound absorption coefficient, the value of standard deviation of the sound absorption coefficient / average sound absorption coefficient x 100 was calculated. The smaller this value, the smaller the variation in the sound absorption coefficient. In addition, as an index 2 of the variation in sound absorption coefficient, the average sound absorption coefficient was calculated by multiplying the total basis weight (g / m) of the nonwoven fabric of layers A to D. 2 ) and multiplied by 100. The smaller this value, the smaller the variation in sound absorption coefficient. The results are shown in the tables as "average sound absorption coefficient," "standard deviation of sound absorption coefficient," "standard deviation of sound absorption coefficient / average sound absorption coefficient x 100," and "average sound absorption coefficient / basis weight x 100."

[0169] [Formula 1] Average sound absorption coefficient = (sound absorption coefficient at 1000Hz + sound absorption coefficient at 1250Hz + sound absorption coefficient at 1600Hz + sound absorption coefficient at 2000Hz + sound absorption coefficient at 2500Hz + sound absorption coefficient at 3150Hz + sound absorption coefficient at 4000Hz + sound absorption coefficient at 5000Hz + sound absorption coefficient at 6300Hz) / 9

[0170] [Formula 2] Standard deviation of sound absorption coefficient = (((sound absorption coefficient at 1000 Hz - average sound absorption coefficient)) 2 + (1250Hz sound absorption coefficient - average sound absorption coefficient) 2 + (1600Hz sound absorption coefficient - average sound absorption coefficient) 2 + (2000Hz sound absorption coefficient - average sound absorption coefficient) 2 + (2500Hz sound absorption coefficient - average sound absorption coefficient) 2 + (sound absorption coefficient at 3150Hz - average sound absorption coefficient) 2 + (4000Hz sound absorption coefficient - average sound absorption coefficient) 2 + (5000Hz sound absorption coefficient - average sound absorption coefficient) 2 + (6300Hz sound absorption coefficient - average sound absorption coefficient) 2 ) / 9) 0.5

[0171] [Table 1]

[0172] [Table 2]

[0173] [Table 3]

[0174] [Table 4]

[0175] [Table 5]

[0176] [Table 6]

[0177] [Table 7]

[0178] [Table 8]

[0179] [Table 9]

[0180] [Table 10]

[0181] As shown in the tables, the sound-absorbing materials of the examples according to the present disclosure exhibited superior sound absorption properties over a wide frequency range above 1000 Hz, which is the high frequency range, compared to the sound-absorbing materials of the comparative examples according to the present disclosure, and the variation in sound absorption coefficient in that frequency range was reduced. It was also found that the sound-absorbing materials of the examples according to the present disclosure also had superior abrasion resistance compared to the sound-absorbing materials of the comparative examples according to the present disclosure.

[0182] The disclosures of Japanese Patent Application No. 2022-061014, filed on March 31, 2022, and Japanese Patent Application No. 2023-006893, filed on January 19, 2023, are incorporated herein by reference in their entirety. All publications, patent applications, and technical standards mentioned in this specification are herein incorporated by reference to the same extent as if each individual publication, patent application, or technical standard was specifically and individually indicated to be incorporated by reference.

Claims

1. The nonwoven fabric has three or more layers including a first spunbond nonwoven fabric, a meltblown nonwoven fabric, and a second spunbond nonwoven fabric, and has an air permeability of 12.9 cc / cm 2 / sec or more and 42 cc / cm ２ / sec or less, and Air permeability is 20cc / cm ２ / sec or more 600cc / cm ２ Layer B is a layer or foam having a viscosity of 1 / sec or less; The nonwoven fabric has three or more layers including the first spunbond nonwoven fabric, the meltblown nonwoven fabric, and the second spunbond nonwoven fabric, and the air permeability is 12.9 cc / cm 2 / sec or more and 42 cc / cm ２ / sec or less, and a layer C; Air permeability is 20cc / cm ２ / sec or more 4500cc / cm ２ / sec or less layer, foam, or back air layer, layer D; in this order in the layer thickness direction from the incident surface side where sound is incident, At least one of the layer A and the layer C has four or more layers of nonwoven fabric, in which a third spunbond nonwoven fabric is further laminated on the outermost surface on the sound incident surface side, the average fiber diameter of the fibers contained in the third spunbond nonwoven fabric is larger than the average fiber diameters of the fibers contained in the first spunbond nonwoven fabric and the second spunbond nonwoven fabric; and, A sound-absorbing material in which the average fiber diameter of the fibers contained in the third spunbond nonwoven fabric is 20 μm or more and 50 μm or less.

2. The nonwoven fabric has three or more layers including a first spunbond nonwoven fabric, a meltblown nonwoven fabric, and a second spunbond nonwoven fabric, and has an air permeability of 12.9 cc / cm 2 / sec or more and 42 cc / cm ２ / sec or less, and Air permeability is 20cc / cm ２ / sec or more 600cc / cm ２ Layer B is a layer or foam having a viscosity of 1 / sec or less; The nonwoven fabric has three or more layers including the first spunbond nonwoven fabric, the meltblown nonwoven fabric, and the second spunbond nonwoven fabric, and the air permeability is 12.9 cc / cm 2 / sec or more and 42 cc / cm ２ / sec or less, and a layer C; Layer D, which is the back air layer; A sound-absorbing material having the above in the layer thickness direction from the incident surface side where sound is incident.

3. The sum ΣACmulti of the product of the air permeability and the thickness of the layer A and the product of the air permeability and the thickness of the layer C is 10 or more and 60 or less, and 3. The sound-absorbing material according to claim 1, wherein a sum ΣACdiv of a value obtained by dividing the air permeability of the layer A by its thickness and a value obtained by dividing the air permeability of the layer C by its thickness is 50 or more and 200 or less.

4. 3. The sound-absorbing material according to claim 1, wherein the layer A and the layer C have the same layer structure.

5. 3. The sound-absorbing material according to claim 1, wherein at least one of the layer B and the layer D contains a polyester resin.

6. The sound-absorbing material according to claim 5 , wherein both the layer B and the layer D contain a polyester-based resin.

7. 3. The sound-absorbing material according to claim 1, wherein the average fiber diameter of the fibers contained in at least one of the first spunbond nonwoven fabric and the second spunbond nonwoven fabric is 8 μm or more and 30 μm or less.

8. The basis weight (g / m ２ ) and the basis weight (g / m ２ 3. The sound-absorbing material according to claim 1, wherein the ratio (Layer A or Layer C / Layer B) of the thickness of the layer A or Layer C to the thickness of the layer B is 0.50 or more.

9. Air permeability of Layer A or Layer C (cc / cm ２ / sec) and the air permeability of layer B (cc / cm ２ 3. The sound-absorbing material according to claim 1, wherein the ratio (Layer A or Layer C / Layer B) of the total length of the sound-absorbing material to the total length of the sound-absorbing material is 0.03 or more and 1.00 or less.

10. 3. The sound-absorbing material according to claim 1, which is a sound-absorbing material for automobiles.

11. 3. The sound-absorbing material according to claim 1, wherein the nonwoven fabric is a conductive nonwoven fabric to which a conductive substance is attached or kneaded.

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