Laminated sound absorbing material

Abstract

To provide an acoustic material having excellent sound absorbing properties in a low frequency region and a medium frequency region, preferably further in a high frequency region. A laminated acoustic material comprising at least a fiber layer and a porous layer, wherein the fiber layer has an average flow pore size of 1.0 μm to 60 μm and an air permeability of 30 cc / cm 2 ·s to 220 cc / cm 2 ·s, the porous layer is a layer comprising at least one selected from the group consisting of a foamed resin, a nonwoven fabric and a woven fabric, has a thickness of 3 mm to 40 mm, a density lower than that of the fiber layer, and is 3 kg / m 3 ·s to 50 kg / m 3 , and is arranged with the fiber layer on the incident side of sound.

Description

TECHNICAL FIELD

[0001] The present application relates to an acoustic material of a laminated structure in which two or more layers are laminated. BACKGROUND

[0002] An acoustic material is a product having a function of absorbing sound, and is used in the fields of construction or automobiles. As a material constituting an acoustic material, a nonwoven fabric is known. For example, in Patent Literature 1, as a multilayered article having sound absorbing properties, an article including a support layer, and a submicron fiber layer laminated on the support layer, the central fiber diameter of the submicron fiber layer being less than 1 μm and the average fiber diameter being in the range of 0.5 μm to 0.7 μm, formed by a melt film fibrillation method or an electrospinning method, is disclosed. In the examples of Patent Literature 1, a laminated article in which a polypropylene spun-bonded nonwoven fabric having a basis weight (weight per unit area) of 100 g / m2and a diameter of about 18 μm is used as a support layer, and a submicron polypropylene fiber having a weight per unit area of 14 g / m2to 50 g / m2and an average fiber diameter of about 0.56 μm is laminated thereon is disclosed. Further, in another example, a multilayered article in which an electrospun polycaprolactone fiber having a weight per unit area of 6 g / m2to 32 g / m2and an average fiber diameter of 0.60 μm is laminated on a carded polyester web having a weight per unit area of 62 g / m2is disclosed. As to the multilayered articles produced in the examples, sound absorption properties are measured, and it is shown that the sound absorption properties are more excellent than those of the support alone. 2 2 2 2 2 2

[0003] Further, it is known that a foamed body is used in an acoustic material. For example, Patent Literature 2 discloses a laminated structure for improving sound comfort (reduction and optimization of the reflection component of sound) and thermal comfort, which includes an organic polymer foamed body having a specific range of open porosity as a support layer, includes a glass cloth as a surface layer having a specific air resistance, and includes a non-continuous adhesive layer between the support layer and the surface layer. It is disclosed that as the organic polymer foamed body, a foamed body based on polyurethane, particularly polyester urethane, neoprene (registered trademark), silicone, or melamine, having a density of preferably 10 kg / m3to 120 kg / m3and a thickness of preferably 1.5 mm to 2.5 mm can be exemplified. 3 3

[0004] ​​​​​​​​Patent Document 3 discloses a multilayer sheet used as an insulator for a vehicle. The multilayer sheet of Patent Document 3 is a sheet in which a first porous sheet and a second porous sheet are integrally fused by a polypropylene-made melt-blown nonwoven fabric inserted therebetween. As the first porous sheet and the second porous sheet, a bonded conjugate nonwoven fabric sheet of short fibers or a glass wool felt sheet or the like is exemplified, a polypropylene-made melt-blown nonwoven fabric having a low air permeability is inserted therebetween, and as the melt-blown nonwoven fabric, a melt-blown nonwoven fabric having an average fiber diameter of 2 μm or less is used, whereby it is considered that the fibers are uniformly dispersed, and even when melted at the time of molding, the low air permeability property of the melt-blown nonwoven fabric is inherited.

[0005] Prior Art Documents

[0006] Patent Documents

[0007] Patent Document 1: Japanese Patent Laid-Open No. 2014-15042

[0008] Patent Document 2: Japanese Patent Laid-Open No. 2014-529524

[0009] Patent Document 3: Japanese Patent Laid-Open No. 2016-137636 SUMMARY

[0010] PROBLEMS TO BE SOLVED BY THE INVENTION

[0011] As described above, as sound absorbing materials, laminates of various structures have been studied, and it is also known to combine a plurality of layers having different fiber diameters or air permeabilities (densities). On the other hand, particularly in sound absorbing materials for vehicles, sound absorbing materials having more excellent sound absorbing properties, particularly exhibiting excellent sound absorbing performance in a low frequency region of 1000 Hz or less and a medium frequency region of 1600 Hz to 2500 Hz, and further in a high frequency region of 5000 Hz to 10000 Hz, and sound absorbing materials excellent in space saving property are required. In view of the above-described circumstances, an object of the present application is to provide a sound absorbing material having excellent sound absorbing properties in a low frequency region and a medium frequency region, and preferably further in a high frequency region.

[0012] TECHNICAL MEANS FOR SOLVING THE PROBLEMS

[0013] The present inventors have made intensive studies in order to solve the problems. As a result, it has been found that the problems can be solved by forming a structure in a laminated sound absorbing material including a porous layer and a fiber layer, the structure including: a dense fiber layer having an average flow pore diameter in a specific range and an air permeability in a specific range, and a sparse porous layer including at least one selected from the group consisting of a foamed resin, a nonwoven fabric, and a woven fabric, having a certain thickness and density, thereby completing the present application.

[0014] The present application has the following structure.

[0015] [1] A laminated sound absorbing material comprising at least a fiber layer and a porous layer, wherein

[0016] the average flow pore size of the fiber layer is 1.0 μm to 60 μm, and the air permeability obtained by a Frazier form method is 30 cc / cm 2 · s ~ 220 cc / cm 2 · s,

[0017] the porous layer is a layer comprising at least one selected from the group consisting of a foamed resin, a nonwoven fabric, and a woven fabric, has a thickness of 3 mm to 40 mm, has a density lower than that of the fiber layer, and is 3 kg / m 3 ~ 50 kg / m 3 ,

[0018] and is arranged so that the fiber layer is on the incident side of sound.

[0019] [2] The laminated sound absorbing material according to [1], wherein the laminated sound absorbing material comprises a first fiber layer and a second fiber layer as the fiber layer,

[0020] the air permeability of the first fiber layer and the second fiber layer is the same as each other, or the air permeability of the second fiber layer is lower than that of the first fiber layer,

[0021] and the first fiber layer, the porous layer, and the second fiber layer are arranged in this order from the incident side to the transmitted side of sound.

[0022] [3] The laminated sound absorbing material according to [2], wherein the laminated sound absorbing material comprises a first porous layer and a second porous layer as the porous layer,

[0023] the density of the first porous layer and the second porous layer is the same as each other, or the density of the second porous layer is higher than that of the first porous layer,

[0024] and the first fiber layer, the first porous layer, the second fiber layer, and the second porous layer are arranged in this order from the incident side to the transmitted side of sound.

[0025] [4] The laminated sound absorbing material according to any one of [1] to [3], wherein the porous layer is a layer comprising a nonwoven fabric or a woven fabric, the nonwoven fabric or the woven fabric comprising at least one fiber selected from the group consisting of polyethylene terephthalate fibers, polybutylene terephthalate fibers, polyethylene fibers, polypropylene fibers, and glass fibers, or a composite fiber composed of two or more kinds.

[0026] [5] The laminated sound absorbing material according to any one of [1] to [4], wherein the fiber layer comprises at least one fiber selected from the group consisting of polyvinylidene fluoride, nylon 6,6, polyacrylonitrile, polystyrene, polyurethane, polysulfone, polyvinyl alcohol, polyethylene terephthalate, polybutylene terephthalate, polyethylene, and polypropylene.

[0027] [6] The laminated sound absorbing material according to any one of [1] to [5], wherein the sound absorption coefficient at a frequency of 500 Hz to 1000 Hz obtained by the normal incidence sound absorption coefficient measurement is improved by 0.03 or more as compared to a case where the porous layer is the only layer included in the laminated sound absorbing material.

[0028] [7] The laminated sound absorbing material according to any one of [1] to [6], wherein the sound absorption coefficient at a frequency of 1600 Hz to 2500 Hz obtained by the normal incidence sound absorption coefficient measurement is improved by 0.03 or more as compared to a case where the porous layer is the only layer included in the laminated sound absorbing material.

[0029] [8] The laminated sound absorbing material according to any one of [1] to [7], wherein the sound absorption coefficient at a frequency of 5000 Hz to 10000 Hz obtained by the normal incidence sound absorption coefficient measurement is improved by 0.03 or more as compared to a case where the porous layer is the only layer included in the laminated sound absorbing material.

[0030] Effects of the Invention

[0031] According to the present application having the above structure, by the fiber layer and the porous layer having a specific structure in the laminated sound absorbing material, high sound absorption can be achieved with a small number of layers, and as a sound absorbing material, the thickness can be reduced. In addition, according to the present application having the above structure, a sound absorbing material having excellent sound absorption properties in the low frequency region and the medium frequency region, and preferably further in the high frequency region, can be obtained. With regard to the laminated sound absorbing material of the present application, the peak of the sound absorption properties is in a lower region than that of the previous sound absorbing material, and the sound absorption performance in the region of 2000 Hz or less, and particularly in the region of 1000 Hz or less, is excellent. In the field of construction, the living noise is around 200 Hz to 500 Hz, and in the field of automobiles, the road noise is around 100 Hz to 500 Hz, and the noise at the time of acceleration or transmission variation is around 100 Hz to 2000 Hz, and the wind noise at the time of vehicle travel is around 800 Hz to 2000 Hz. The laminated sound absorbing material of the present application is useful in dealing with such noise. In addition, since the laminated sound absorbing material of the present application is lighter than a sound absorbing material including a porous material or glass fiber, etc., it is possible to achieve lightweight and space saving of the member, and this aspect is particularly useful as a sound absorbing material for the field of automobiles. BRIEF DESCRIPTION OF DRAWINGS

[0032] Figure 1 is a graph showing sound absorption characteristics of the embodiment (Example 1) and Comparative Example 1 of the present application.

[0033] Figure 2 is a graph showing sound absorption characteristics of the embodiment (Example 10) and Comparative Example 7 of the present application.

[0034] Figure 3 is a graph showing sound absorption characteristics of the embodiment (Example 22) and Comparative Example 7 of the present application.

[0035] Figure 4 is a graph showing sound absorption characteristics of the embodiment (Example 30) and Comparative Example 1 of the present application. DETAILED DESCRIPTION

[0036] Hereinafter, the present application will be described in detail.

[0037] (Structure of the laminated sound absorbing material)

[0038] The laminated sound absorbing material of the present application is a laminated sound absorbing material comprising at least a fiber layer and a porous layer, wherein the average flow pore diameter of the fiber layer is 1.0 μm to 60 μm, the air permeability obtained by the Frazier method is 30 cc / cm 2 to 220 cc / cm 2 , the porous layer is a layer comprising at least one selected from the group consisting of foamed resin, nonwoven fabric and woven fabric, has a thickness of 3 mm to 40 mm, has a density lower than that of the fiber layer, and is 3 kg / m 3 to 50 kg / m 3 , and is arranged so that the fiber layer is on the incident side of sound.

[0039] In the laminated sound absorbing material, the fiber layer comprises at least one layer, and specifically, can be one layer to two layers, and more preferably one layer from the viewpoint of reducing the thickness of the sound absorbing material. Each fiber layer can be one fiber aggregate, or can be a form in which a plurality of fiber aggregates are overlapped in one fiber layer. In addition, in the laminated sound absorbing material, at least one fiber layer is arranged on the incident side of sound.

[0040] The fiber layer and the porous layer included in the laminated sound absorbing material can each be one kind, or can comprise two or more different kinds of fiber layers or porous layers. In addition, a structure other than the fiber layer and the porous layer can also be included, for example, a further fiber layer (which can be one layer, or two or more layers), a printed layer, a foam, a foil, a mesh, a woven fabric, etc. outside the range specified in the present application can also be included, without impairing the effects of the present application. In addition, an adhesive layer, a clip, a suture, etc. for joining between the layers can also be included.

[0041] The laminated sound absorbing material of the present application is a two-layer laminate in which a fibrous layer is disposed on the sound incident side and a porous layer is disposed on the sound transmission side, or a three-layer laminate in which a porous layer is interposed between a first fibrous layer and a second fibrous layer, or a four-layer laminate in which the layers are laminated in the order of a first fibrous layer / a first porous layer / a second fibrous layer / a second porous layer. In the case where two fibrous layers are included, the first fibrous layer and the second fibrous layer can have the same density as each other or different densities. In the latter case, it is preferable that the density of the second fibrous layer on the sound transmission side be higher than that of the first fibrous layer. In the case where two porous layers are included, the first porous layer and the second porous layer can have the same density as each other or different densities. In the latter case, it is preferable that the density of the second porous layer on the sound transmission side be higher than that of the first porous layer.

[0042] The layers of the laminated sound absorbing material can be physically and / or chemically bonded or not bonded. It can also be a state in which some of the layers are bonded and some of the layers are not bonded. The bonding can be performed, for example, by heating in the step of forming the fibrous layer or as a post step to cause a part of the fibers constituting the fibrous layer to melt and thereby fuse the fibrous layer to the porous layer, thereby bonding the fibrous layer to the porous layer. Alternatively, it is also preferable to bond the layers by applying an adhesive to the surface of the porous layer or even the fibrous layer and further forming the porous layer or even the fibrous layer into multiple layers, thereby bonding the layers.

[0043] The thickness of the laminated sound absorbing material is not particularly limited as long as the effects of the present application can be obtained, and can be set to, for example, 3 mm to 50 mm, preferably 3 mm to 40 mm, more preferably 3 mm to 30 mm from the viewpoint of space saving. Further, the thickness of the laminated sound absorbing material typically refers to the total of the thickness of the fibrous layer and the porous layer, and does not include the thickness of the outer body such as a cartridge or a cover, which is attached.

[0044] The air permeability of the laminated sound absorbing material is not particularly limited as long as the desired sound absorbing performance can be obtained, and can be set to, for example, 30 cc / cm 2 ·s to 500 cc / cm 2 ·s, preferably 45 cc / cm 2 ·s to 220 cc / cm 2 ·s, preferably 45 cc / cm 2 ·s to 220 cc / cm 2 ·s, more preferably. If the air permeability is 30 cc / cm 2 ·s or more, the sound absorbing rate does not decrease due to the reflection of sound from the surface of the sound absorbing material, and if the air permeability is 500 cc / cm 2• s is below, the tortuosity inside the sound absorbing material does not decrease, and the dissipated energy inside the sound absorbing material does not decrease. In addition, it is preferable that the density of the fiber layer be higher than the density of the porous layer, in other words, it is preferable that the layer having a relatively low density (the porous layer) be located on the sound transmission side more than the layer having a high density (the fiber layer), or be a structure sandwiched by the fiber layer. In the past, in a sound absorbing material in which sound absorbing performance and sound insulating performance are expected, the higher the density, the more difficult it is for sound to pass through, and it is considered to be effective for sound insulating performance. The laminated sound absorbing material of the present application can obtain high sound absorbing performance by employing a porous layer that reduces the reflection of sound due to high air permeability, and further has excellent sound absorbing performance. With respect to adjustment of the air permeability, for example, a fiber layer having a high density and low air permeability can be obtained by providing the fiber constituting the fiber layer with a fine diameter. In addition, the air permeability can also be adjusted by methods such as embossing or heat pressing. Furthermore, the air permeability can be measured using a known method, for example, a Frazier method.

[0045] The laminated sound absorbing material is a laminated structure in which the porous layer is located on the downstream side of the fiber layer (the sound transmission side), or the porous layer is sandwiched by the fiber layer. In the case of the porous layer being sandwiched by the fiber layer, the distance between the fiber layer and the fiber layer (also referred to as the thickness of the porous layer, the interlayer distance) is preferably 3 mm to 40 mm. If the interlayer distance is 3 mm or more, the sound absorbing performance in the low frequency region becomes good, and if the interlayer distance is 40 mm or less, the thickness of the sound absorbing material does not become excessively large, and a sound absorbing material excellent in space saving can be obtained. The sound absorbing material of the present application is typically preferably a structure in which a porous layer having a thickness is interposed between thin fiber layers and fiber layers, and the thickness of the porous layer is preferably a large portion of the thickness of the laminated sound absorbing material.

[0046] (Structure of each layer: fiber layer)

[0047] The fiber layer included in the laminated sound absorbing material of the present application is a layer including fibers having an average fiber diameter of 30 nm to 30 μm. It is preferable that the layer include fibers having an average fiber diameter of 50 nm to 30 μm. By the average fiber diameter being 30 nm to 30 μm, it means that the average fiber diameter is within the numerical range. If the fiber diameter is in the range of 30 nm to 30 μm, high sound absorbing performance can be obtained, and thus it is preferable. The fiber diameter can be measured using a known method. For example, it is a value obtained by measuring or calculating from an enlarged photograph of the surface of the fiber layer. The detailed measurement method is described in detail in the examples.

[0048] As for the fiber layer included in the laminated sound absorbing material of the present application, one fiber layer can be formed of one fiber aggregate, or a plurality of fiber aggregates included in one fiber layer and the layers of the fiber aggregates can be formed into one fiber layer. Further, in the present specification, the fiber aggregate refers to a fiber aggregate that is a continuous body. The unit area weight of the fiber layer is preferably 0.01 g / m 2 ~ 500 g / m 2 , and more preferably 0.1 g / m 2 ~ 200 g / m 2 . If the unit area weight is 0.1 g / m 2 or more, control of flow resistance caused by the difference in density between the fiber layer and the porous layer becomes good, and if it is less than 500 g / m 2 , the productivity as a sound absorbing material is excellent. From the viewpoint of reducing the thickness of the sound absorbing material, it is preferable that the thickness of the fiber layer be thin, specifically, less than 2.9 mm, more preferably less than 2.0 mm, further preferably less than 1.5 mm, and particularly preferably less than 1 mm.

[0049] The air permeability of the fiber layer is 30 cc / cm 2 · s ~ 220 cc / cm 2 · s, preferably 40 cc / cm 2 · s ~ 220 cc / cm 2 · s. It is considered that if the air permeability is 30 cc / cm 2 · s or more, sound generated from a sound source can be introduced into the inside of the sound absorbing material, and thus sound can be absorbed efficiently, and if it is 220 cc / cm · s or less, the flow of sound waves to the inside of the porous layer can be adjusted, and thus it is preferable. In addition, the average flow pore diameter of the fiber layer can be 1.0 μm ~ 100 μm, and if it is 1.0 μm ~ 60 μm, it is more preferable. It is considered that if the average flow pore diameter is 1.0 μm or more, the reflected wave can be suppressed, and sound can be taken into the inside of the sound absorbing material, and if it is 100 μm or less, in the fiber layer and the porous layer controlled by the density, sound can be efficiently disappeared in the inside of the sound absorbing material by being closed to the inside of the sound absorbing material, and thus it is preferable.

[0050] The fiber aggregate that constitutes the fiber layer is preferably a nonwoven fabric, and is not particularly limited as long as it has the fiber diameter and the unit area weight in the range described above, and is preferably a spunbond nonwoven fabric, a meltblown nonwoven fabric, a nonwoven fabric formed by an electrospinning method, or the like. According to the meltblown nonwoven fabric, fine-diameter fibers can be efficiently laminated on a base material or other members. Details of the meltblown nonwoven fabric will be described in the manufacturing method.

[0051] As the resin constituting the fiber layer, there is no particular limitation as long as the effect of the present application can be obtained, and for example, polyolefin-based resins, polyurethane, polylactic acid, acrylic resins, polyesters such as polyethylene terephthalate or polybutylene terephthalate, nylons (amide resins) such as nylon 6, nylon 6,6, nylon 1,2, polyphenylene sulfide, polyvinyl alcohol, polystyrene, polysulfone, liquid crystal polymers, polyethylene-vinyl acetate copolymers, polyacrylonitrile, polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene, and the like can be exemplified. As the polyolefin-based resin, polyethylene resins and polypropylene resins can be exemplified. As the polyethylene resin, low-density polyethylene (LDPE), high-density polyethylene (HDPE), linear low-density polyethylene (LLDPE), and the like can be exemplified, and as the polypropylene resin, homopolymers of propylene or copolymerized polypropylenes obtained by polymerizing propylene with other monomers such as ethylene or butene, and the like can be exemplified. The fiber aggregate preferably contains one of the resins, and can contain two or more kinds of the resins.

[0052] In addition, the fiber layer is preferably a spun-bonded nonwoven fabric using flat yarns having a flat cross-sectional shape. Specifically, for example, a spun-bonded nonwoven fabric using flat yarns of polyolefin-based resins (polypropylene, polyethylene), polyethylene terephthalate, nylon, or the like having a fineness of 0.01 dtex to 20 dtex can be produced and used, and commercially available products can also be used. In the case of using commercially available products, for example, ELTAS FLAT, ELTAS emboss (trade name, manufactured by Asahi Kasei Corporation), and the like can be preferably used. The spun-bonded nonwoven fabric using flat yarns is considered to be preferably used in the laminated sound-absorbing material of the present application because of low weight per unit area, thin thickness, and high density.

[0053] In addition, various additives other than resins can be contained in the fibers. As the additives that can be added to the resins, for example, fillers, stabilizers, plasticizers, adhesives, adhesion promoters (for example, silane and titanate), silica, glass, clay, talc, pigments, colorants, antioxidants, optical brighteners, antibacterial agents, surfactants, flame retardants, and fluorinated polymers can be exemplified. By using one or more of the additives, the weight of the obtained fibers and layers can be reduced and / or the cost can be reduced, the viscosity can be adjusted, or the thermal properties of the fibers can be modified, or various physical properties derived from the properties of the additives, such as electrical properties, optical properties, density-related properties, and properties related to liquid barrier or adhesion, can be imparted.

[0054] (Structure of each layer: porous layer)

[0055] The porous layer in the laminated sound absorbing material of the present application has sound absorbing properties and functions to support the fibrous layer while maintaining the shape of the sound absorbing material as a whole. The porous layer can be composed of one layer of porous layer, or can be in a form in which a plurality of porous layers are overlapped. The porous layer is characterized in that the density obtained by the Frazier method is lower than that of the fibrous layer, and is a layer containing at least one selected from the group consisting of foamed resin, nonwoven fabric, and woven fabric, has a thickness of 3 to 40 mm, and has a density of 3 to 50 kg / m 3 3 .

[0056] In the case where the member constituting the porous layer is nonwoven fabric or woven fabric, the nonwoven fabric or woven fabric is preferably composed of at least one fiber selected from the group consisting of polyethylene terephthalate fiber, polybutylene terephthalate fiber, polyethylene fiber, polypropylene fiber, and glass fiber, or a composite fiber composed of two or more thereof.

[0057] In the case where the member constituting the porous layer is foamed resin, a layer containing urethane foamed resin or melamine foamed resin is particularly preferred. The member contained in the laminated sound absorbing material can be one, and is preferably composed of two or more members. These are particularly preferred to have air permeability, and thus in the case where the air permeability is low, it is preferred to have an open cell. The foamed resin is preferably foamed resin having continuous cells (communicating pores).

[0058] As the resin constituting the foamed resin, for example, polyolefin-based resin, polyurethane-based resin, and melamine-based resin can be exemplified. As the polyolefin-based resin, homopolymers of ethylene, propylene, butene-1, or 4-methylpentene-1, or random copolymers or block copolymers of these and one or more other α-olefins, i.e., ethylene, propylene, butene-1, pentene-1, hexene-1, or 4-methylpentene-1, or copolymers composed of combinations of these, or mixtures of these, or the like can be exemplified.

[0059] In the laminated sound absorbing material of the present application, the porous layer is located on the downstream side of the fibrous layer (the sound transmission side), or between the fibrous layers. In addition, it can be contained as a layer located on the outermost side of the laminated sound absorbing material, in addition to being located between the fibrous layers. As to the member, the porous layer can be composed of one layer, or two or more members are preferably continuously arranged to constitute one porous layer. By continuously arranging two or more members, the advantage that the distance between the layers can be controlled by the thickness of the porous layer is obtained.

[0060] The density of the porous layer is 3 to 50 kg / m 3 3 , and is preferably 6 to 50 kg / m 3 ​​~ 45 kg / m 3 As the foamed resin layer, a foamed resin layer having continuous air bubbles (communicating pores) is preferable, and urethane foamed resin, acrylic foamed resin, melamine foamed resin, or the like can be exemplified. If the density is 3 kg / m 3 or more, the moldability is good and it is generally commercially available, and thus is preferable in terms of easy availability. If the density is 50 kg / m 3 or less, it is lightweight as an acoustic material, and the workability at the time of installation or the like is high, and thus is preferable.

[0061] In the present application, the porous layer preferably has a thickness of 3 mm or more. The upper limit of the thickness of the porous layer is not particularly limited, and from the viewpoint of space saving, it is preferably 3 mm to 60 mm, and more preferably 3 mm to 40 mm. In the case where the porous layer includes a plurality of members, the thickness of each layer of the members constituting the porous layer can be, for example, 20 μm to 60 mm, and is preferably 3 mm to 60 mm. If the thickness of the member is 20 μm or more, wrinkles do not occur, handling is easy, and the productivity is good, and if the thickness of the member is 60 mm or less, there is no concern that space saving is hindered.

[0062] The porous layer is a layer having a thickness and a low density compared to the fibrous layer, and it is considered that by this structure, the reflection of sound is reduced, and the acoustic absorption property is improved. The air permeability of the porous layer can be, for example, 10 cc / cm 2 or more.

[0063] In a range not impairing the effects of the present application, various additives such as colorants, antioxidants, light stabilizers, ultraviolet absorbers, neutralizing agents, nucleating agents, lubricants, antibacterial agents, flame retardants, plasticizers, and other thermoplastic resins can be added to the porous layer. In addition, the surface can be treated with various finishing agents, and thereby water repellency, antistatic properties, surface smoothness, wear resistance, and the like can be imparted.

[0064] (Acoustic absorption properties of the laminated acoustic material)

[0065] The laminated sound-absorbing material of the present invention is characterized by excellent sound absorption, particularly in the low-frequency range (500 Hz to 1000 Hz or less), the mid-frequency range (1600 Hz to 2500 Hz), and preferably in the high-frequency range (5000 Hz to 10000 Hz). The laminated sound-absorbing material of the present invention exhibits excellent sound absorption in the 500 Hz to 1000 Hz range, a characteristic that differs from conventional sound-absorbing materials. While not being bound by any particular theory, the laminated sound-absorbing material of the present invention utilizes the density difference between the fiber layer and the porous layer to control the flow resistance of sound waves, and utilizes the transmission, reflection, and interference of sound waves. As a result, it is believed that the laminated sound-absorbing material of the present invention is a thin-walled sound-absorbing material that achieves excellent absorption in the low-frequency, mid-frequency, and high-frequency ranges.

[0066] The method for evaluating the sound absorption is described in detail in the Examples.

[0067] The laminated sound absorbing material of the present invention preferably has a sound absorption rate at a frequency of 500 Hz to 1000 Hz, as measured by the normal incidence sound absorption rate measurement method, which is improved by 0.03 or more compared to the sound absorption rate when the laminated sound absorbing material comprises only one porous layer. Furthermore, the laminated sound absorbing material of the present invention preferably has a sound absorption rate at a frequency of 1600 Hz to 2500 Hz, as measured by the normal incidence sound absorption rate measurement method, which is improved by 0.03 or more compared to the sound absorption rate when the laminated sound absorbing material comprises only one porous layer. Furthermore, the laminated sound absorbing material of the present invention preferably has a sound absorption rate at a frequency of 5000 Hz to 10000 Hz, as measured by the normal incidence sound absorption rate measurement method, which is improved by 0.03 or more compared to the sound absorption rate when the laminated sound absorbing material comprises only one porous layer.

[0068] (Method for producing laminated sound-absorbing material)

[0069] The method for producing a laminated sound-absorbing material is not particularly limited. For example, the laminated sound-absorbing material can be produced by a method comprising: forming a fiber layer comprising a fiber assembly on a porous layer; and integrating the plurality of fiber layers by stacking them in a predetermined order and number. Furthermore, during the stacking step, additional layers (e.g., additional protective layers) may be added to the stacking process.

[0070] The foamed resin, nonwoven fabric, and / or woven fabric used as the porous layer may be produced by a known method and used, or a commercially available product may be selected and used.

[0071] The method of integrating the obtained laminate including the two layers of the porous layer and the fiber layer by overlapping multiple pieces is not particularly limited, and can be simply overlapping without bonding, or various bonding methods such as heat press bonding using a flat roll or an embossed roll, bonding using a hot melt agent or a chemical adhesive, heat bonding using circulating hot air or radiant heat, and the like. From the viewpoint of suppressing a decrease in the properties of the fiber layer, heat treatment using circulating hot air or radiant heat is preferred. In the case of heat press bonding using a flat roll or an embossed roll, the fiber layer is melted and filmized, or damaged at the periphery of the embossed points, and the like, and there is a possibility that stable production is difficult, and in addition, there is a possibility that a decrease in performance such as a decrease in sound absorption properties occurs. In the case of bonding using a hot melt agent or a chemical adhesive, the inter-fiber spaces of the fiber layer are sometimes filled with the components, and a decrease in performance is likely to occur. On the other hand, in the case of integration by heat treatment based on circulating hot air or radiant heat, damage to the fiber layer is small, and integration with sufficient interlayer peeling strength is possible, and thus is preferred. In the case of integration by heat treatment based on circulating hot air or radiant heat, there is no particular limitation, and a nonwoven fabric including heat fusible composite fibers and a foamed resin are preferably used.

[0072] Example

[0073] Hereinafter, the present application will be described in more detail using examples, and the following examples are merely for the purpose of illustration. The scope of the present application is not limited to the present examples.

[0074] Hereinafter, the measurement method and definition of the physical property values used in the examples are shown.

[0075] <Average fiber diameter>

[0076] A scanning electron microscope SU8020 manufactured by Hitachi High-technologies, Inc. was used to observe the fibers, and the diameters of 50 fibers were measured using image analysis software. The average of the fiber diameters of the 50 fibers was used as the average fiber diameter.

[0077] <Sound absorption rate measurement 1>

[0078] A sample having a diameter of 15 mm was collected from each of the fiber layer and the porous layer, and after lamination under each condition, a vertical incidence sound absorption rate measuring device "WinZac MTX manufactured by Nippon Sound Engineering Co., Ltd." was used to measure the vertical incidence sound absorption rate when a vertical incidence plane sound wave was applied to the test piece at a frequency of 400 Hz to 10,000 Hz in accordance with American Society of Testing Materials (ASTM) E 1050.

[0079] Sound absorption in low frequency region

[0080] The sound absorption rate was measured in one-third octave bands of the sound absorption of the obtained sample, and compared with a sample without the fiber layer to evaluate the improvement. The vertical incidence sound absorption rate of each sample was measured in 1 / 3 octave bands, the difference was calculated, and this was evaluated. The improvement in sound absorption performance in the frequency region of 500 to 1000 Hz was shown, and if the value was high, it was judged that the improvement in sound absorption was high. In the case where the value at all measurement points (specifically, 500 Hz, 630 Hz, 800 Hz, 1000 Hz) was 0.03 or more, the improvement in sound absorption in the low frequency region was evaluated as good (O), and in the case where there was a measurement point less than 0.03, the improvement in sound absorption was evaluated as poor (X).

[0081] Sound absorption in medium frequency region

[0082] The frequency domain to be evaluated in the low frequency region was set to 1600 to 2500 Hz, and the improvement was calculated at 1600 Hz, 2000 Hz, and 2500 Hz, and otherwise, the evaluation was the same as the sound absorption in the low frequency region.

[0083] Sound absorption in high frequency region

[0084] The frequency domain to be evaluated in the low frequency region was set to 5000 to 10000 Hz, and the improvement was calculated at 5000 Hz, 6300 Hz, 8000 Hz, and 10000 Hz, and otherwise, the evaluation was the same as the sound absorption in the low frequency region.

[0085] Air permeability

[0086] The air permeability measurement was performed using a cloth air permeability tester (Frazier type method) manufactured by Toyo Tekkosho Co., Ltd. in accordance with Japanese Industrial Standards (JIS) L1913.

[0087] Thickness

[0088] The thickness measurement was performed using a DIGI thickness tester manufactured by Toyo Tekkosho Co., Ltd. in accordance with JIS K6767, with 3.5 g / cm 2 pressure at 35 mm.

[0089] Melt flow rate (MFR)

[0090] The MFR of the polypropylene resin was a value obtained by measurement in accordance with JIS K 7210 (1999) under a load of 2160 g at 230°C.

[0091] The MFR of the polyethylene resin was a value obtained by measurement in accordance with JIS K 7210 (1999) under a load of 2160 g at 190°C.

[0092] <Preparation of protective layer>

[0093] As the protective layer, a commercially available carded hot air nonwoven fabric made of polyethylene terephthalate (unit area weight 18 g / m 2 , thickness 60 μm) was prepared.

[0094] <Preparation of fiber layer>

[0095] Fiber layer A, fiber layer B, fiber layer C

[0096] Polyvinylidene fluoride-hexafluoropropylene (hereinafter, abbreviated as "PVDF-HFP") manufactured by Arkema, Kynar (trade name) 3120 was dissolved in a co-solvent (60 / 40 (w / w)) of N,N-dimethylacetamide and acetone at a concentration of 15 mass%, and an electric field spinning solution was prepared, with 0.01 mass% of a conductive aid added. The PVDF-HFP solution was electric field spun on the protective layer, and a fiber layer laminate comprising the protective layer and the PVDF-HFP ultrafine fiber was produced. The conditions for electric field spinning were a 24G needle, a single-hole solution supply amount of 3.0 mL / h, an applied voltage of 35 kV, and a spinning distance of 17.5 cm.

[0097] As for the PVDF ultrafine fiber in the fiber layer laminate, the unit area weight of the layer was 0.2 g / m 2 , the average fiber diameter was 80 nm, and the melting temperature was 168°C. This was set as fiber layer A. The average flow pore diameter was evaluated, and the result was 5.8 μm, and the air permeability obtained by the Frazier method was 47 cc / cm 2 ·s.

[0098] In addition, the conveyance speed of the protective layer was changed so as to adjust the unit area weight to 0.6 g / m 2 . The average fiber diameter of the obtained fiber layer was 80 nm, and the melting temperature was 168°C. This was set as fiber layer B. The average flow pore diameter was evaluated, and the result was 1.5 μm, and the air permeability obtained by the Frazier method was 10 cc / cm 2 ·s.

[0099] Further, the unit area weight was adjusted to 3.0 g / m 2The average flow pore size was evaluated to be 0.7 μm, and the air permeability obtained by the Frazier method was 0.7 cc / cm 2 ·s.

[0100] Fiber layer D, fiber layer E, fiber layer F, fiber layer G, fiber layer H, fiber layer I, fiber layer J, fiber layer K (spun-bonded nonwoven fabric)

[0101] As the nonwoven fabric material commercially available, ELTAS (registered trademark) FLATEH5025 (thickness 0.11 mm) manufactured by Asahi Kasei Corp. was used as the fiber layer D, EH5035 (thickness 0.14 mm) as the fiber layer E, EH5035C (thickness 0.06 mm) as the fiber layer F, ELTAS E01100 (thickness 0.44 mm) as the fiber layer G, E05030 (thickness 0.15 mm) as the fiber layer H, E01030 (thickness 0.20 mm) as the fiber layer I, E01025 (thickness 0.17 mm) as the fiber layer J, and EH5045C (thickness 0.07 mm) as the fiber layer K. Further, the fiber layer D, the fiber layer E, and the fiber layer F were spun-bonded nonwoven fabrics using flat filaments, and as to the fiber diameter, it was a fiber having an elliptical long axis diameter of 40 μm and a short axis diameter of 5 μm. The average flow pore size of the fiber layer D was 41 μm, and the air permeability obtained by the Frazier method was 138 cc / cm 2 ·s. The average flow pore size of the fiber layer E was 28 μm, and the air permeability obtained by the Frazier method was 70 cc / cm 2 ·s. The average flow pore size of the fiber layer F was 18 μm, and the air permeability obtained by the Frazier method was 22 cc / cm 2 ·s.

[0102] Fiber layer M (melt-blown nonwoven fabric)

[0103] As the polypropylene resin of the raw material of the fiber layer, polypropylene homopolymer 1 (MFR = 70 g / 10 min) was used, and the polypropylene resin was fed to two extruders of a nonwoven fabric manufacturing device, and the extruders were set to be heated and melted at 240°C and the mass ratio of the gear pump was 50 / 50, and the melted resin was ejected from the spinning nozzle at a spinning speed of 0.3 g / min per single hole. The ejected fiber was blown onto a collection conveyor at a distance of 60 cm from the spinning nozzle using compressed air of 98 kPa (gauge pressure) heated to 400°C, and a fiber layer was formed. The weight per unit area was arbitrarily set by adjusting the speed of the collection conveyor. The average fiber diameter was 2.6 μm, and the weight per unit area of the fiber layer was 24 g / m 2, and the thickness was 0.9 mm. The average flow pore size of the fiber layer M was 11 μm, and the air permeability obtained using the Frazier method was 144 cc / cm 2 ·s.

[0104] Fiber layer N (melt-blown nonwoven fabric)

[0105] The fiber layer was formed using a nonwoven fabric manufacturing apparatus including two extruders having a screw (50 mm in diameter), a heating body, and a gear pump, a fiber mixing spin nozzle (0.3 mm in diameter, 501 holes arranged in a row, effective width 500 mm, the number of holes alternately ejecting resins from the two extruders, an air compression device, and an air heater, a polyester net-equipped collection conveyor, and a winding machine.

[0106] As the raw material polypropylene, polypropylene homopolymer 1 (MFR = 82 g / 10 min) and polypropylene homopolymer 2 ("FR-185" manufactured by LOTTE CHEMICAL, MFR = 1400 g / 10 min) were used, and the two kinds of polypropylene were put into the two extruders of the nonwoven fabric manufacturing apparatus, and the extruders were set to heat and melt at 240°C and the mass ratio of the gear pump was 50 / 50, and the molten resin was ejected from the spin nozzle at a spinning speed of 0.3 g / min per single hole. The ejected fibers were blown onto the collection conveyor at a distance of 60 cm from the spin nozzle using air compression at 98 kPa (gauge pressure) heated to 400°C, and a fiber layer was formed. By adjusting the speed of the collection conveyor, the weight per unit area was set to 80 g / m 2 The average fiber diameter was 1.3 μm, and it was set as the fiber layer N. The average flow pore size was evaluated, and the result was 9.4 μm, and the air permeability obtained using the Frazier method was 15 cc / cm 2 ·s.

[0107] [Preparation of porous layer]

[0108] Porous layer α, porous layer β, porous layer γ (urethane foamed foam)

[0109] Calmflex F-2 (density 25 kg / m 3 ) manufactured by Inoac Corporation, which is a commercially available urethane foaming resin material, was set as the porous layer α, and Calmflex F-2 (density 25 kg / m 3 ) was set as the porous layer β, and Calmflex F-2 (density 25 kg / m 3 ) was set as the porous layer γ. The air permeability obtained using the Frazier method was 50 cc / cm2 • s, the porous layer β is 70 cc / cm 2 • s, the porous layer γ is 180 cc / cm 2 • s.

[0110] Porous layer δ, porous layer ζ, porous layer θ (air-laid)

[0111] As a high-density polyethylene resin, high-density polyethylene "M6900" (MFR = 17 g / 10 minutes) manufactured by KEIYO was used, and as a polypropylene resin, polypropylene homopolymer "SA3A" (MFR = 11 g / 10 minutes) manufactured by Japan Polypropylene was used, and a sheath-core type hot-melt adhesive composite fiber in which the sheath component contains a high-density polyethylene resin and the core component contains a polypropylene resin was produced by a hot melt spinning method. Using the obtained sheath-core type hot-melt adhesive composite fiber, a carded hot air nonwoven fabric having a weight per unit area of 200 g / m 2 , a thickness of 5 mm, and a width of 1000 mm was produced. The carded hot air nonwoven fabric was pulverized to about 8 mm or less using a single-shaft type pulverizer (ES3280) manufactured by Seishin Enterprise Co., Ltd. The pulverized nonwoven fabric was heated at a set temperature of 142°C using an air-laying tester, and a porous layer δ having a weight per unit area of 1050 g / m 2 , a thickness of 25 mm, a porous layer ζ having a weight per unit area of 210 g / m 2 , a thickness of 20 mm, and a porous layer θ having a weight per unit area of 80 g / m 2 , a thickness of 5 mm were obtained. The density of the porous layer δ was 42 kg / m 3 , and the air permeability was 130 cc / cm 2 • s. The density of the porous layer ζ was 42 kg / m 3 , and the air permeability was 150 cc / cm 2 • s. The density of the porous layer θ was 42 kg / m 3 , and the air permeability was 250 cc / cm 2 • s.

[0112] Porous layer ε, porous layer η, porous layer κ (glass fiber)

[0113] As a commercially available glass fiber material, Aclear mat (trade name) manufactured by Asahi Fiber Glass Co., Ltd. was processed to have a weight per unit area of 400 g / m 2 , a thickness of 50 mm, and was used as the porous layer ε. In addition, it was processed to have a weight per unit area of 320 g / m 2 , a thickness of 20 mm, and was used as the porous layer η. In addition, it was processed to have a weight per unit area of 80 g / m 2, thickness 5 mm, as a porous layer κ. The density of the porous layer ε was 16 kg / m 3 , the air permeability was 150 cc / cm 2 .s. The density of the porous layer η was 16 kg / m 3 , the air permeability was 170 cc / cm 2 .s. The density of the porous layer κ was 16 kg / m 3 , the air permeability was 300 cc / cm 2 .s.

[0114] [Example 1]

[0115] The first fiber layer used the fiber layer A, and the porous layer α was used to overlap in the manner of fiber layer A / porous layer α, a 15 mm diameter circle was cut out, and a sound absorption rate measurement sample was prepared. The low frequency region sound absorption rate, the medium frequency region sound absorption rate, and the high frequency region sound absorption rate were measured. A sample in which the fiber layer A was not present (Comparative Example 1) was used as a control, the difference from the sound absorption rate thereof was obtained, and the improvement amplitude was calculated. The improvement amplitude was 0.186 or more in the low frequency region, and 0.159 or more in the medium frequency region, and was good. Furthermore, with respect to the sound absorption rate in the high frequency region, the difference from the sound absorption rate thereof was similarly obtained, and the improvement amplitude was calculated, and the result was 0.069 or more, and was good.

[0116] [Example 2]

[0117] The first fiber layer used the fiber layer D, and the porous layer α was used to overlap in the manner of fiber layer D / porous layer α, a 15 mm diameter circle was cut out, and a sound absorption rate measurement sample was prepared. The low frequency region sound absorption rate, the medium frequency region sound absorption rate, and the high frequency region sound absorption rate were measured. Comparative Example 1 was used as a control, the difference from the sound absorption rate thereof was obtained, and the improvement amplitude was calculated. The improvement amplitude was 0.180 or more in the low frequency region, and 0.101 or more in the medium frequency region, and was good.

[0118] [Example 3]

[0119] The first fiber layer used the fiber layer E, and the porous layer α was used to overlap in the manner of fiber layer E / porous layer α, a 15 mm diameter circle was cut out, and a sound absorption rate measurement sample was prepared. The low frequency region sound absorption rate, the medium frequency region sound absorption rate, and the high frequency region sound absorption rate were measured. Comparative Example 1 was used as a control, the difference from the sound absorption rate thereof was obtained, and the improvement amplitude was calculated. The improvement amplitude was 0.179 or more in the low frequency region, and 0.082 or more in the medium frequency region, and was good.

[0120] [Example 4]

[0121] The first fiber layer used the fiber layer G, and the porous layer α was used to overlap in the manner of fiber layer G / porous layer α, a 15 mm diameter circle was cut out, and a sound absorption rate measurement sample was prepared. The sound absorption rates in the low frequency region, the middle frequency region, and the high frequency region were measured. Comparative Example 1 was used as a control, the difference from the sound absorption rate thereof was obtained, and the improvement rate was calculated. The improvement rate was 0.235 or more in the low frequency region, and 0.070 or more in the middle frequency region, which was good.

[0122] [Example 5]

[0123] The first fiber layer used the fiber layer M, and the porous layer α was used to overlap in the manner of fiber layer M / porous layer α, a 15 mm diameter circle was cut out, and a sound absorption rate measurement sample was prepared. The sound absorption rates in the low frequency region, the middle frequency region, and the high frequency region were measured. Comparative Example 1 was used as a control, the difference from the sound absorption rate thereof was obtained, and the improvement rate was calculated. The improvement rate was 0.195 or more in the low frequency region, and 0.081 or more in the middle frequency region, which was good.

[0124] [Example 6]

[0125] The first fiber layer used the fiber layer A, and the porous layer δ was used to overlap in the manner of fiber layer A / porous layer δ, a 15 mm diameter circle was cut out, and a sound absorption rate measurement sample was prepared. The sound absorption rates in the low frequency region, the middle frequency region, and the high frequency region were measured. Comparative Example 2 (porous layer δ alone) was used as a control, the difference from the sound absorption rate thereof was obtained, and the improvement rate was calculated. The improvement rate was 0.04 or more in the low frequency region, and 0.117 or more in the middle frequency region, which was good.

[0126] [Example 7]

[0127] The first fiber layer used the fiber layer G, and the porous layer δ was used to overlap in the manner of fiber layer G / porous layer δ, a 15 mm diameter circle was cut out, and a sound absorption rate measurement sample was prepared. The sound absorption rates in the low frequency region, the middle frequency region, and the high frequency region were measured. Comparative Example 2 was used as a control, the difference from the sound absorption rate thereof was obtained, and the improvement rate was calculated. The improvement rate was 0.119 or more in the low frequency region, and 0.125 or more in the middle frequency region, which was good.

[0128] [Example 8]

[0129] The first fiber layer used the fiber layer A, and the porous layer ε was used, and a 15 mm diameter circle was cut out in a manner so as to overlap the fiber layer A / porous layer ε, and a sound absorption rate measurement sample was prepared. The sound absorption rates in the low frequency region, the middle frequency region, and the high frequency region were measured, and the difference from the sound absorption rate of the sample of Comparative Example 3, which did not have a fiber layer, was obtained, and the improvement rate was calculated. The improvement rate was 0.043 or more in the low frequency region, and 0.245 or more in the middle frequency region, and was good.

[0130] [Example 9]

[0131] The first fiber layer used the fiber layer H, and the porous layer α was used, and a 15 mm diameter circle was cut out in a manner so as to overlap the fiber layer H / porous layer α, and a sound absorption rate measurement sample was prepared. The sound absorption rates in the low frequency region, the middle frequency region, and the high frequency region were measured. Comparative Example 1 was used as a control, and the difference from the sound absorption rate thereof was obtained, and the improvement rate was calculated. The improvement rate was 0.110 or more in the low frequency region, and 0.173 or more in the middle frequency region, and was good.

[0132] [Comparative Example 1]

[0133] Only the porous layer α (thickness 25 mm) was cut out in a 15 mm diameter circle, and a sound absorption rate measurement sample was prepared, and the sound absorption rates in the low frequency region, the middle frequency region, and the high frequency region were measured. The difference in the sound absorption rate of the sample was 0 in the low frequency region, the middle frequency region, and the high frequency region, since it was still the sound absorption rate thereof, and was poor.

[0134] [Comparative Example 2]

[0135] Only the porous layer δ (thickness 25 mm) was cut out in a 15 mm diameter circle, and a sound absorption rate measurement sample was prepared, and the sound absorption rates in the low frequency region, the middle frequency region, and the high frequency region were measured. The difference in the sound absorption rate of the sample was 0 in the low frequency region, the middle frequency region, and the high frequency region, since it was still the sound absorption rate thereof, and was poor.

[0136] [Comparative Example 3]

[0137] Only the porous layer ε (thickness 25 mm) was cut out in a 15 mm diameter circle, and a sound absorption rate measurement sample was prepared, and the sound absorption rates in the low frequency region, the middle frequency region, and the high frequency region were measured. The difference in the sound absorption rate of the sample was 0 in the low frequency region, the middle frequency region, and the high frequency region, since it was still the sound absorption rate thereof, and was poor.

[0138] [Comparative Example 4]

[0139] The first fiber layer used the fiber layer J, and the porous layer α was used to overlap in the manner of fiber layer J / porous layer α, a 15 mm diameter circle was cut out, and a sound absorption rate measurement sample was made. The sound absorption rates in the low frequency region, the middle frequency region, and the high frequency region were measured. Comparative Example 1 was used as a control, the difference from the sound absorption rate thereof was obtained, the improvement rate was calculated, and as a result, in the low frequency region, it was 0.002 or more, in the middle frequency region, it was 0.003 or more, and it was not good.

[0140] [Comparative Example 5]

[0141] The first fiber layer used the fiber layer C, and the porous layer α was used to overlap in the manner of fiber layer C / porous layer α, a 15 mm diameter circle was cut out, and a sound absorption rate measurement sample was made. The sound absorption rates in the low frequency region, the middle frequency region, and the high frequency region were measured. Comparative Example 1 was used as a control, the difference from the sound absorption rate thereof was obtained, the improvement rate was calculated, and as a result, in the low frequency region, the middle frequency region, and the high frequency region, no improvement tendency was confirmed.

[0142] [Comparative Example 6]

[0143] The first fiber layer used the fiber layer F, and the porous layer α was used to overlap in the manner of fiber layer F / porous layer α, a 15 mm diameter circle was cut out, and a sound absorption rate measurement sample was made. The sound absorption rates in the low frequency region, the middle frequency region, and the high frequency region were measured. Comparative Example 1 was used as a control, the difference from the sound absorption rate thereof was obtained, the improvement rate was calculated, and as a result, in the low frequency region, it was 0.141 or more, which was good, but in the middle frequency region, it was 0.021 or more, which was not good.

[0144] The structures of Examples 1 to 9 were summarized in Table 1, and the structures of Comparative Examples 1 to 6 were summarized in Table 2. The sound absorption rates of Examples 1 to 9 were summarized in Table 3, the sound absorption rates of Comparative Examples 1 to 6 were summarized in Table 4, and the improvement rates of the sound absorption rates were summarized in Tables 5 and 6.

[0145] [Table 1]

[0146]

[0147] [Table 2]

[0148] Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Comparative Example 5 Comparative Example 6 First fiber layer - - - Fiber layer J Fiber layer C Fiber layer F Fiber material - - - PP PVDF PP Fiber diameter (μm) - - - 15 0.08 5x40 weight (g / m 2 )]]> - - - 25 3 30 Density (kg / m3 3 )]]> - - - 147 214 500 Thickness (mm) - - - 0.17 0.014 0.06 Ventilation (cc / cm 2 • sec) - - - 280 0.7 22 First porous layer Porous layer α Porous layer δ Porous layer ε Porous layer α Porous layer α Porous layer α Material PU foam PP / PE fiber Glass fiber PU foam PU foam PU foam Density (kg / m3 3 )]]> 25 42 16 25 25 25 Thickness (mm) 25 25 25 25 25 25 Ventilation (cc / cm 2 • sec) 50 130 150 50 50 50

[0149] [Table 3]

[0150] Normal incidence sound absorption coefficient Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Example 7 Example 8 Example 9 500 Hz 0.355 0.349 0.348 0.404 0.364 0.285 0.355 0.217 0.279 630 Hz 0.451 0.444 0.443 0.517 0.478 0.381 0.418 0.261 0.352 800 Hz 0.578 0.565 0.561 0.649 0.620 0.509 0.509 0.336 0.463 1000 Hz 0.698 0.689 0.705 0.744 0.710 0.639 0.654 0.435 0.545 1600 Hz 0.867 0.925 0.928 0.935 0.954 0.896 0.896 0.710 0.811 2000 Hz 0.973 0.957 0.951 0.941 0.950 0.962 0.971 0.817 0.918 2500 Hz 0.918 0.860 0.842 0.829 0.841 0.986 0.994 0.889 0.932 5000 Hz 0.948 0.942 0.953 0.937 0.946 0.921 0.916 0.948 0.888 6300 Hz 0.983 0.924 0.938 0.924 0.930 0.929 0.930 0.907 0.988 8000 Hz 0.976 0.923 0.928 0.901 0.917 0.989 0.991 0.881 0.997 10000 Hz 0.980 0.956 0.955 0.940 0.953 0.977 0.967 0.950 0.998

[0151] [Table 4]

[0152] Normal incidence sound absorption coefficient Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Comparative Example 5 Comparative Example 6 500 Hz 0.169 0.236 0.161 0.172 0.090 0.310 630 Hz 0.202 0.297 0.218 0.212 0.100 0.406 800 Hz 0.257 0.376 0.265 0.259 0.120 0.547 1000 Hz 0.335 0.465 0.313 0.344 0.260 0.689 1600 Hz 0.514 0.704 0.466 0.524 0.400 0.981 2000 Hz 0.627 0.799 0.542 0.637 0.560 0.929 2500 Hz 0.759 0.868 0.608 0.763 0.580 0.780 5000 Hz 0.759 0.954 0.851 0.787 0.500 0.853 6300 Hz 0.819 0.940 0.901 0.826 0.520 0.837 8000 Hz 0.901 0.947 0.846 0.956 0.520 0.926 10000 Hz 0.911 0.960 0.818 0.912 0.320 0.920

[0153] [Table 5]

[0154] Sound absorption coefficient improvement width Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Example 7 Example 8 Example 9 500 Hz 0.186 0.180 0.179 0.235 0.195 0.049 0.119 0.056 0.110 630 Hz 0.249 0.242 0.241 0.315 0.275 0.084 0.121 0.043 0.150 800 Hz 0.321 0.308 0.304 0.392 0.363 0.133 0.133 0.071 0.206 1000 Hz 0.363 0.354 0.370 0.409 0.376 0.173 0.189 0.122 0.211 Low frequency region evaluation ○ ○ ○ ○ ○ ○ ○ ○ ○ 1600 Hz 0.352 0.411 0.414 0.421 0.440 0.191 0.192 0.245 0.297 2000 Hz 0.346 0.330 0.324 0.314 0.323 0.162 0.172 0.275 0.291 2500 Hz 0.159 0.101 0.082 0.070 0.081 0.117 0.125 0.282 0.173 Mid frequency region evaluation ○ ○ ○ ○ ○ ○ ○ ○ ○

[0155] [Table 6]

[0156] Sound absorption coefficient improvement width Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Comparative Example 5 Comparative Example 6 500 Hz 0 0 0 0.003 -0.079 0.141 630 Hz 0 0 0 0.010 -0.102 0.203 800 Hz 0 0 0 0.002 -0.137 0.290 1000 Hz 0 0 0 0.009 -0.075 0.355 Low frequency region evaluation × × × × × ○ 1600 Hz 0 0 0 0.010 -0.114 0.467 2000 Hz 0 0 0 0.010 -0.067 0.302 2500 Hz 0 0 0 0.003 -0.179 0.021 Mid frequency region evaluation × × × × × ×

[0157] [Example 10]

[0158] The first fiber layer used the fiber layer A, and the porous layer β was used, and a 15 mm diameter circle was cut out to make a sound absorption rate measuring sample in the manner of the fiber layer A / porous layer β being overlapped. The sound absorption rate in the low frequency region, the middle frequency region, and the high frequency region was measured. Comparative Example 7 (only the porous layer β) was used as a control, and the difference from the sound absorption rate thereof was obtained, and the improvement rate was calculated, and as a result, in the low frequency region, it was 0.113 or more, and in the middle frequency region, it was 0.033 or more, and it was good.

[0159] [Example 11]

[0160] The first fiber layer used the fiber layer E, and the porous layer β was used, and a 15 mm diameter circle was cut out to make a sound absorption rate measuring sample in the manner of the fiber layer E / porous layer β being overlapped. The sound absorption rate in the low frequency region, the middle frequency region, and the high frequency region was measured. Comparative Example 7 was used as a control, and the difference from the sound absorption rate thereof was obtained, and the improvement rate was calculated, and as a result, in the low frequency region, it was 0.030 or more, and in the middle frequency region, it was 0.039 or more, and it was good.

[0161] [Example 12]

[0162] The first fiber layer used the fiber layer G, and the porous layer β was used, and a 15 mm diameter circle was cut out to make a sound absorption rate measuring sample in the manner of the fiber layer G / porous layer β being overlapped. The sound absorption rate in the low frequency region, the middle frequency region, and the high frequency region was measured. Comparative Example 7 was used as a control, and the difference from the sound absorption rate thereof was obtained, and the improvement rate was calculated, and as a result, in the low frequency region, it was 0.085 or more, and in the middle frequency region, it was 0.063 or more, and it was good.

[0163] [Example 13]

[0164] The first fiber layer used the fiber layer M, and the porous layer β was used, and a 15 mm diameter circle was cut out to make a sound absorption rate measuring sample in the manner of the fiber layer M / porous layer β being overlapped. The sound absorption rate in the low frequency region, the middle frequency region, and the high frequency region was measured. Comparative Example 7 was used as a control, and the difference from the sound absorption rate thereof was obtained, and the improvement rate was calculated, and as a result, in the low frequency region, it was 0.040 or more, and in the middle frequency region, it was 0.034 or more, and it was good.

[0165] [Example 14]

[0166] The first fiber layer used the fiber layer A, and the porous layer ζ was used, and the sound absorption rate measuring sample was prepared by cutting a 15 mm diameter circle in a manner that the fiber layer A / porous layer ζ was overlapped. The sound absorption rates in the low frequency region, the middle frequency region, and the high frequency region were measured. Comparative Example 8 (only the porous layer ζ) was used as a control, and the difference from the sound absorption rate thereof was obtained, and the improvement rate was calculated, and as a result, it was 0.086 or more in the low frequency region, and 0.211 or more in the middle frequency region, and it was good.

[0167] [Example 15]

[0168] The first fiber layer used the fiber layer G, and the porous layer ζ was used, and the sound absorption rate measuring sample was prepared by cutting a 15 mm diameter circle in a manner that the fiber layer G / porous layer ζ was overlapped. The sound absorption rates in the low frequency region, the middle frequency region, and the high frequency region were measured. Comparative Example 8 was used as a control, and the difference from the sound absorption rate thereof was obtained, and the improvement rate was calculated, and as a result, it was 0.031 or more in the low frequency region, and 0.056 or more in the middle frequency region, and it was good.

[0169] [Example 16]

[0170] The first fiber layer used the fiber layer A, and the porous layer η was used, and the sound absorption rate measuring sample was prepared by cutting a 15 mm diameter circle in a manner that the fiber layer A / porous layer η was overlapped. The sound absorption rates in the low frequency region, the middle frequency region, and the high frequency region were measured. Comparative Example 9 (only the porous layer η) was used as a control, and the difference from the sound absorption rate thereof was obtained, and the improvement rate was calculated, and as a result, it was 0.039 or more in the low frequency region, and 0.279 or more in the middle frequency region, and it was good.

[0171] [Comparative Example 7]

[0172] Only the porous layer β (thickness 25 mm) was cut into a 15 mm diameter circle, and the sound absorption rate measuring sample was prepared. The difference in the sound absorption rate of the sample was still the sound absorption rate of itself, and it was 0 in the low frequency region, the middle frequency region, and the high frequency region, and no improvement effect was found.

[0173] [Comparative Example 8]

[0174] Only the porous layer ζ (thickness 20 mm) was cut into a 15 mm diameter circle, and the sound absorption rate measuring sample was prepared. The difference in the sound absorption rate of the sample was still the sound absorption rate of itself, and it was 0 in the low frequency region, the middle frequency region, and the high frequency region, and no improvement effect was found.

[0175] [Comparative Example 9]

[0176] Only the porous layer η (thickness 20 mm) was cut out in a circular shape of 15 mm in diameter to make a sample for sound absorption rate measurement. As for the difference in sound absorption rate of the sample, since it was still its own sound absorption rate, it was 0 in the low frequency region, the medium frequency region, and the high frequency region, and no improvement effect was found.

[0177] [Comparative Example 10]

[0178] The first fiber layer used the fiber layer J, and the porous layer β was used to be overlaid in the manner of fiber layer J / porous layer β, a circular shape of 15 mm in diameter was cut out to make a sample for sound absorption rate measurement. The sound absorption rate in the low frequency region, the medium frequency region, and the high frequency region was measured. Comparative Example 7 was taken as a control to obtain the difference in sound absorption rate, and the improvement rate was calculated, and the result was 0.003 or more in the low frequency region, 0.002 or more in the medium frequency region, and the improvement rate was small, and it was bad.

[0179] [Comparative Example 11]

[0180] The first fiber layer used the fiber layer F, and the porous layer β was used to be overlaid in the manner of fiber layer F / porous layer β, a circular shape of 15 mm in diameter was cut out to make a sample for sound absorption rate measurement. The sound absorption rate in the low frequency region, the medium frequency region, and the high frequency region was measured. Comparative Example 7 was taken as a control to obtain the difference in sound absorption rate, and the improvement rate was calculated, and the result was 0.081 or more in the low frequency region, but no improvement tendency was confirmed in the medium frequency region.

[0181] As for Examples 10 to 16, Comparative Examples 7 to 11, the structures are summarized in Table 7, as for the normal incidence sound absorption rate, it is summarized in Table 8, and as for the improvement rate of the sound absorption rate, it is summarized in Table 9.

[0182]

[0183]

[0184] [Example 17]

[0185] The first fiber layer used the fiber layer A, the second fiber layer used the fiber layer B, and the porous layer used the porous layer β, and a circular shape of 15 mm in diameter was cut out to make a sample for sound absorption rate measurement. The sound absorption rate in the low frequency region, the medium frequency region, and the high frequency region was measured. Comparative Example 7 (only the porous layer β) was taken as a control to obtain the difference in sound absorption rate, and the improvement rate was calculated, and the result was 0.171 or more in the low frequency region, and 0.035 or more in the medium frequency region, and it was good.

[0186] [Example 18]

[0187] The first fiber layer used the fiber layer D, the second fiber layer used the fiber layer K, and the porous layer used the porous layer β, and they were overlapped in the order of the fiber layer D / porous layer β / fiber layer K, and a circular shape with a diameter of 15 mm was cut out to produce a sound absorption rate measurement sample. The sound absorption rates in the low frequency region, the middle frequency region, and the high frequency region were measured. The difference from the sound absorption rate of Comparative Example 7 was obtained, and the improvement rate was calculated. As a result, the improvement rate was 0.037 or more in the low frequency region, and 0.037 or more in the middle frequency region, and was good.

[0188] [Example 19]

[0189] The first fiber layer used the fiber layer E, the second fiber layer used the fiber layer K, and the porous layer used the porous layer β, and they were overlapped in the order of the fiber layer E / porous layer β / fiber layer K, and a circular shape with a diameter of 15 mm was cut out to produce a sound absorption rate measurement sample. The sound absorption rates in the low frequency region, the middle frequency region, and the high frequency region were measured. The difference from the sound absorption rate of Comparative Example 7 was obtained, and the improvement rate was calculated. As a result, the improvement rate was 0.038 or more in the low frequency region, and 0.050 or more in the middle frequency region, and was good.

[0190] [Example 20]

[0191] The first fiber layer used the fiber layer G, the second fiber layer used the fiber layer K, and the porous layer used the porous layer β, and they were overlapped in the order of the fiber layer G / porous layer β / fiber layer K, and a circular shape with a diameter of 15 mm was cut out to produce a sound absorption rate measurement sample. The sound absorption rates in the low frequency region, the middle frequency region, and the high frequency region were measured. The difference from the sound absorption rate of Comparative Example 7 was obtained, and the improvement rate was calculated. As a result, the improvement rate was 0.103 or more in the low frequency region, and 0.040 or more in the middle frequency region, and was good.

[0192] [Example 21]

[0193] The first fiber layer used the fiber layer M, the second fiber layer used the fiber layer N, and the porous layer used the porous layer β, and they were overlapped in the order of the fiber layer M / porous layer β / fiber layer N, and a circular shape with a diameter of 15 mm was cut out to produce a sound absorption rate measurement sample. The sound absorption rates in the low frequency region, the middle frequency region, and the high frequency region were measured. The difference from the sound absorption rate of Comparative Example 7, which did not have a fiber layer, was obtained, and the improvement rate was calculated. As a result, the improvement rate was 0.036 or more in the low frequency region, and 0.033 in the middle frequency region, and was good.

[0194] [Example 22]

[0195] The first fiber layer used the fiber layer A, the second fiber layer used the fiber layer B, and the porous layer used the porous layer ζ, and they were overlaid in the manner of fiber layer A / porous layer ζ / fiber layer B, and a 15 mm diameter circle was cut out to make a sound absorption rate measurement sample. The sound absorption rates in the low frequency region, the middle frequency region, and the high frequency region were measured. Comparative Example 8 was used as a control, and the difference from its sound absorption rate was obtained, and the improvement rate was calculated. As a result, it was 0.130 or more in the low frequency region, and 0.214 or more in the middle frequency region, and was good.

[0196] [Example 23]

[0197] The first fiber layer used the fiber layer G, the second fiber layer used the fiber layer K, and the porous layer used the porous layer ζ, and they were overlaid in the manner of fiber layer G / porous layer ζ / fiber layer K, and a 15 mm diameter circle was cut out to make a sound absorption rate measurement sample. The sound absorption rates in the low frequency region, the middle frequency region, and the high frequency region were measured. Comparative Example 8 was used as a control, and the difference from its sound absorption rate was obtained, and the improvement rate was calculated. As a result, it was 0.097 or more in the low frequency region, and 0.177 or more in the middle frequency region, and was good.

[0198] [Example 24]

[0199] The first fiber layer used the fiber layer A, the second fiber layer used the fiber layer B, and the porous layer used the porous layer η, and they were overlaid in the manner of fiber layer A / porous layer η / fiber layer B, and a 15 mm diameter circle was cut out to make a sound absorption rate measurement sample. The sound absorption rates in the low frequency region, the middle frequency region, and the high frequency region were measured. Comparative Example 9 was used as a control, and the difference from its sound absorption rate was obtained, and the improvement rate was calculated. As a result, it was 0.141 or more in the low frequency region, and 0.277 or more in the middle frequency region, and was good.

[0200] [Comparative Example 12]

[0201] The first fiber layer used the fiber layer J, the second fiber layer used the fiber layer K, and the porous layer used the porous layer β, and they were overlaid in the manner of fiber layer J / porous layer β / fiber layer K, and a 15 mm diameter circle was cut out to make a sound absorption rate measurement sample. The sound absorption rates in the low frequency region, the middle frequency region, and the high frequency region were measured. Comparative Example 7 was used as a control, and the difference from its sound absorption rate was obtained, and the improvement rate was calculated. As a result, it was 0.002 or more in the low frequency region, and no improvement tendency was confirmed in the middle frequency region.

[0202] [Comparative Example 13]

[0203] The first fiber layer used the fiber layer F, the second fiber layer used the fiber layer K, and the porous layer β was used, and a sample for sound absorption rate measurement was prepared by cutting a 15 mm diameter circle in a manner that the fiber layer F / porous layer β / fiber layer K was overlapped. The sound absorption rates in the low frequency region, the middle frequency region, and the high frequency region were measured. Comparative Example 7 was used as a control, and the difference from the sound absorption rate thereof was obtained, and the improvement rate was calculated, and as a result, it was 0.093 or more in the low frequency region, and was good, and no improvement tendency was confirmed in the middle frequency region.

[0204] Regarding Examples 17 to 24 and Comparative Examples 12 to 13, the structures are summarized in Table 10, the normal incidence sound absorption rates are summarized in Table 11, and the improvement rates of the sound absorption rates are summarized in Table 12.

[0205] [Table 10]

[0206]

[0207] [Table 11]

[0208]

[0209] [Table 12]

[0210]

[0211] [Example 25]

[0212] The first fiber layer used the fiber layer A, the second fiber layer used the fiber layer B, the porous layer used the porous layer β and the porous layer γ, and a sample for sound absorption rate measurement was prepared by cutting a 15 mm diameter circle in a manner that the fiber layer A / porous layer β / fiber layer B / porous layer γ was overlapped. The sound absorption rates in the low frequency region, the middle frequency region, and the high frequency region were measured, and Comparative Example 1 was used as a control, and the difference from the sound absorption rate thereof was obtained, and the improvement rate was calculated, and as a result, it was 0.142 or more in the low frequency region, 0.213 or more in the middle frequency region, and 0.034 or more in the high frequency region, and was good.

[0213] [Example 26]

[0214] The first fiber layer used the fiber layer D, the second fiber layer used the fiber layer K, the porous layer used the porous layer β and the porous layer γ, and a sample for sound absorption rate measurement was prepared by cutting a 15 mm diameter circle in a manner that the fiber layer D / porous layer β / fiber layer K / porous layer γ was overlapped. The sound absorption rates in the low frequency region, the middle frequency region, and the high frequency region were measured, and Comparative Example 1 was used as a control, and the difference from the sound absorption rate thereof was obtained, and the improvement rate was calculated, and as a result, it was 0.061 or more in the low frequency region, 0.176 or more in the middle frequency region, and 0.056 or more in the high frequency region, and was good.

[0215] [Example 27]

[0216] The first fiber layer used the fiber layer E, the second fiber layer used the fiber layer K, the porous layer used the porous layer β, the porous layer γ, and was overlaid in a manner to become the fiber layer E / porous layer β / fiber layer K / porous layer γ, a 15 mm diameter circle was cut out, and a sound absorption rate measurement sample was produced. The sound absorption rates in the low frequency region, the middle frequency region, and the high frequency region were measured, Comparative Example 1 was used as a control, the difference from the sound absorption rate thereof was obtained, the improvement rate was calculated, and as a result, in the low frequency region, it was 0.118 or more, in the middle frequency region, it was 0.204 or more, and in the high frequency region, it was 0.034 or more, which was good.

[0217] [Example 28]

[0218] The first fiber layer used the fiber layer G, the second fiber layer used the fiber layer K, the porous layer used the porous layer β, the porous layer γ, and was overlaid in a manner to become the fiber layer G / porous layer β / fiber layer K / porous layer γ, a 15 mm diameter circle was cut out, and a sound absorption rate measurement sample was produced. The sound absorption rates in the low frequency region, the middle frequency region, and the high frequency region were measured, Comparative Example 1 was used as a control, the difference from the sound absorption rate thereof was obtained, the improvement rate was calculated, and as a result, in the low frequency region, it was 0.093 or more, in the middle frequency region, it was 0.206 or more, and in the high frequency region, it was 0.044 or more, which was good.

[0219] [Example 29]

[0220] The first fiber layer used the fiber layer A, the second fiber layer used the fiber layer B, the porous layer used the porous layer ζ, the porous layer θ, and was overlaid in a manner to become the fiber layer A / porous layer ζ / fiber layer B / porous layer θ, a 15 mm diameter circle was cut out, and a sound absorption rate measurement sample was produced. The sound absorption rates in the low frequency region, the middle frequency region, and the high frequency region were measured, Comparative Example 2 was used as a control, the difference from the sound absorption rate thereof was obtained, the improvement rate was calculated, and as a result, in the low frequency region, it was 0.059 or more, in the middle frequency region, it was 0.112 or more, and in the high frequency region, it was 0.034 or more, which was good.

[0221] [Example 30]

[0222] The first fiber layer used the fiber layer G, the second fiber layer used the fiber layer K, the porous layer used the porous layer ζ, the porous layer θ, and was overlaid in a manner to become the fiber layer G / porous layer ζ / fiber layer K / porous layer θ, a 15 mm diameter circle was cut out, and a sound absorption rate measurement sample was produced. The sound absorption rates in the low frequency region, the middle frequency region, and the high frequency region were measured, Comparative Example 2 was used as a control, the difference from the sound absorption rate thereof was obtained, the improvement rate was calculated, and as a result, in the low frequency region, it was 0.072 or more, in the middle frequency region, it was 0.122 or more, and in the high frequency region, it was 0.030 or more, which was good.

[0223] [Example 31]

[0224] The first fiber layer was used as the fiber layer A, the second fiber layer was used as the fiber layer B, the porous layer was used as the porous layer η and the porous layer was used as the porous layer κ, and they were overlaid in the order of the fiber layer A / porous layer η / fiber layer B / porous layer κ, and a circular shape having a diameter of 15 mm was cut out to prepare a sound absorption rate measurement sample. The sound absorption rates in the low frequency region, the middle frequency region and the high frequency region were measured, and the difference from Comparative Example 3 was obtained, and the improvement rate was calculated. As a result, it was 0.068 or more in the low frequency region, 0.262 or more in the middle frequency region, and 0.083 or more in the high frequency region, and it was good.

[0225] [Comparative Example 14]

[0226] The first fiber layer was used as the fiber layer J, the second fiber layer was used as the fiber layer K, the porous layer was used as the porous layer β and the porous layer was used as the porous layer γ, and they were overlaid in the order of the fiber layer J / porous layer β / fiber layer K / porous layer γ, and a circular shape having a diameter of 15 mm was cut out to prepare a sound absorption rate measurement sample. The sound absorption rates in the low frequency region, the middle frequency region and the high frequency region were measured, and the difference from Comparative Example 1 was obtained, and the improvement rate was calculated. As a result, it was 0.060 or more in the middle frequency region, and 0.072 or more in the high frequency region, and it was good, but the improvement rate was 0.002 in the low frequency region, and it was not good.

[0227] The structures of Examples 25 to 31 and Comparative Example 14 were summarized in Table 13, the normal incidence sound absorption rates were summarized in Table 14, and the improvement rates of the sound absorption rates were summarized in Table 15.

[0228] [Table 13]

[0229]

[0230] [Table 14]

[0231] Normal incidence sound absorption coefficient Example 25 Example 26 Example 27 Example 28 Example 29 Example 30 Example 31 Comparative Example 14 500 Hz 0.311 0.230 0.287 0.262 0.295 0.308 0.228 0.207 630 Hz 0.395 0.305 0.353 0.351 0.368 0.374 0.288 0.245 800 Hz 0.509 0.403 0.415 0.470 0.470 0.491 0.376 0.306 1000 Hz 0.635 0.504 0.453 0.606 0.605 0.638 0.476 0.337 1600 Hz 0.810 0.766 0.887 0.781 0.876 0.908 0.728 0.574 2000 Hz 0.949 0.883 0.957 0.931 0.949 0.969 0.825 0.712 2500 Hz 0.972 0.935 0.964 0.965 0.981 0.991 0.893 0.822 5000 Hz 0.904 0.923 0.911 0.908 0.988 0.986 0.984 0.967 6300 Hz 0.943 0.970 0.944 0.961 0.976 0.987 0.984 0.994 8000 Hz 0.950 0.958 0.935 0.945 0.993 0.984 0.991 0.989 10000 Hz 0.946 0.974 0.964 0.962 0.997 0.990 0.995 0.983

[0232] [Table 15]

[0233] Sound absorption coefficient improvement width Example 25 Example 26 Example 27 Example 28 Example 29 Example 30 Example 31 Comparative Example 14 500 Hz 0.142 0.061 0.118 0.093 0.059 0.072 0.068 0.038 630 Hz 0.193 0.103 0.151 0.148 0.071 0.077 0.070 0.043 800 Hz 0.252 0.146 0.158 0.212 0.095 0.116 0.111 0.049 1000 Hz 0.3 0.169 0.118 0.271 0.139 0.172 0.164 0.002 Low frequency region evaluation ○ ○ ○ ○ ○ ○ ○ × 1600 Hz 0.296 0.252 0.373 0.267 0.172 0.204 0.262 0.060 2000 Hz 0.322 0.256 0.330 0.305 0.149 0.169 0.283 0.085 2500 Hz 0.213 0.176 0.204 0.206 0.112 0.122 0.285 0.063 Mid frequency region evaluation ○ ○ ○ ○ ○ ○ ○ ○ 5000 Hz 0.145 0.164 0.151 0.148 0.034 0.032 0.133 0.208 6300 Hz 0.124 0.151 0.125 0.142 0.037 0.047 0.083 0.175 8000 Hz 0.048 0.056 0.034 0.044 0.046 0.037 0.145 0.087 10000 Hz 0.034 0.062 0.053 0.051 0.037 0.030 0.177 0.072 High frequency region evaluation ○ ○ ○ ○ ○ ○ ○ ○

[0234] Industrial Applicability

[0235] The laminated sound absorbing material of the present application is particularly excellent in sound absorption in the low frequency region to the medium frequency region, and thus can be used as a sound absorbing material in a field in which noise in the low frequency region to the medium frequency region is a problem. Specifically, it can be used as a sound absorbing material used in a ceiling, a wall, a floor, or the like of a house, a soundproof wall of a highway or a railway line, or the like, a soundproof material of a household electrical product, a sound absorbing material arranged in each portion of a railway or a vehicle such as an automobile, or the like.

Claims

1. A laminated sound absorbing material comprising at least a fiber layer and a porous layer, wherein: The average flow pore diameter of the fiber layer is 1.0 μm to 60 μm, and the air permeability obtained by the Frazier method is 30 cc / cm 2 ·s~220cc / cm 2 ·s, the average fiber diameter of the fiber layer is 30nm~30μm, The porous layer is a layer comprising at least one selected from the group consisting of foamed resin, non-woven fabric and woven fabric, with a thickness of 3 mm to 40 mm and a density lower than that of the fiber layer and 3 kg / m 3 ~45kg / m 3 , The fiber layer is arranged so as to be the incident side of sound.

2. The laminated sound-absorbing material according to claim 1, wherein the fiber layers include a first fiber layer and a second fiber layer. The air permeability of the first fiber layer and the second fiber layer is the same as each other, or the air permeability of the second fiber layer is lower than that of the first fiber layer, The first fiber layer, the porous layer, and the second fiber layer are arranged in order from the incident side to the transmission side of sound.

3. The laminated sound absorbing material according to claim 2, comprising a first porous layer and a second porous layer as the porous layer, The first porous layer and the second porous layer have the same density, or the second porous layer has a higher density than the first porous layer. The first fiber layer, the first porous layer, the second fiber layer, and the second porous layer are arranged in this order from the incident side to the transmission side of sound.

4. The laminated sound-absorbing material according to any one of claims 1 to 3, wherein the porous layer is a layer comprising a nonwoven fabric or a woven fabric, wherein the nonwoven fabric or the woven fabric comprises at least one fiber selected from the group consisting of polyethylene phthalate fibers, polybutylene terephthalate fibers, polyethylene fibers, polypropylene fibers, and glass fibers, or a composite fiber comprising two or more of the fibers.

5. The laminated sound-absorbing material according to any one of claims 1 to 3, wherein the fiber layer comprises at least one fiber selected from the group consisting of polyvinylidene fluoride, nylon 6,6, polyacrylonitrile, polystyrene, polyurethane, polysulfone, polyvinyl alcohol, polyethylene phthalate, polybutylene terephthalate, polyethylene, and polypropylene.

6. The laminated sound absorbing material according to any one of claims 1 to 3, wherein the sound absorption rate at a frequency of 500 Hz to 1000 Hz obtained by a normal incidence sound absorption rate measurement method is improved by 0.03 or more compared to the sound absorption rate when the laminated sound absorbing material comprises only one porous layer.

7. The laminated sound absorbing material according to any one of claims 1 to 3, wherein the sound absorption rate at a frequency of 1600 Hz to 2500 Hz obtained by a normal incidence sound absorption rate measurement method is improved by 0.03 or more compared to the sound absorption rate when the laminated sound absorbing material comprises only one porous layer.

8. The laminated sound absorbing material according to any one of claims 1 to 3, wherein the sound absorption rate at a frequency of 5000 Hz to 10000 Hz obtained by a normal incidence sound absorption rate measurement method is improved by 0.03 or more compared to the sound absorption rate when the laminated sound absorbing material comprises only one porous layer.

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