Sound-absorbing material

Abstract

To provide a sound absorption material with excellent sound absorption characteristics for a wide range of sound frequencies from a low frequency range of about 850 Hz to a high frequency range of about 5,000 Hz.SOLUTION: A sound absorbing material comprises a base material, a porous layer with longitudinal pores extending in a thickness direction on one side of the base material, and a ventilation layer on the other side of the base material, where the porous layer side is a sound source side.SELECTED DRAWING: Figure 1

Description

Technical Field

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

Background Art

[0002] The porous resin film is widely used in various applications, for example, as a sound-absorbing material, a separation filter, a cushioning material, synthetic leather, a heat insulating material, an insulating material, and the like. The sound-absorbing material is used, for example, to absorb sound from a noise source in a building, an electrical product, a vehicle, etc. and reduce noise. For example, a porous material used for building materials or the like for the purpose of sound absorption or sound insulation is disclosed in Patent Document 1. The porous material described in Patent Document 1 has a hollow layer that houses, inside a base material, one of a powder having a resonance frequency in the mid-low frequency range and a powder having a characteristic of vibrating at a predetermined frequency or higher in the mid-low frequency range, and continuous holes that open on the surface of the base material.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the above Patent Document 1, the sound absorption characteristics of the porous material are evaluated based on the sound absorption rate at 125 Hz or higher and 2000 Hz or lower. However, depending on the place where the porous material is used, it is required to exhibit absorption characteristics also for sounds in a high frequency range exceeding 2000 Hz, for example, about 5000 Hz.

[0005] The present invention has been made paying attention to the above circumstances, and an object thereof is to provide a sound-absorbing material having excellent sound absorption characteristics for sounds of a wide range of frequencies from a low frequency range of about 850 Hz to a high frequency range of about 5000 Hz.

Means for Solving the Problems

[0006] The present invention is as follows. [1] A sound-absorbing material having a base material, a porous layer having vertically elongated holes extending in the thickness direction on one surface side of the base material, and a ventilation layer on the other surface side of the base material, wherein the porous layer side is the sound source side. [2] The sound-absorbing material according to [1], wherein the ratio of the length of the hole to the diameter of the hole (hole length / hole diameter) of the vertically elongated hole is 1.6 or more. [3] The sound-absorbing material according to [1] or [2], wherein in the cross section in the thickness direction of the sound-absorbing material, the average porosity of the ventilation layer is larger than the average porosity of the porous layer. [4] The sound-absorbing material according to any one of [1] to [3], wherein the porous layer is formed by a wet coagulation method. [5] The sound-absorbing material according to any one of [1] to [4], wherein the specific gravity of the porous layer is larger than the specific gravity of the ventilation layer. [6] The sound-absorbing material according to any one of [1] to [5], wherein the specific gravity of the porous layer is 0.15 or more and 1.0 or less. [7] The sound-absorbing material according to any one of [1] to [6], wherein the specific gravity of the ventilation layer is 0.01 or more and 0.1 or less. [8] The sound-absorbing material according to any one of [1] to [7], wherein openings exist on the surface of the porous layer. [9] The sound-absorbing material according to any one of [1] to [8], wherein the ventilation layer is a foam.

[10] The sound-absorbing material according to any one of [1] to [9], wherein the normal incidence sound absorption rate measured according to the test method of JIS A1405-2 is 0.3 or more at a frequency of 850 Hz or more and 5000 Hz or less.

[11] The sound-absorbing material according to

[10] , wherein the curve showing the normal incidence sound absorption rate with respect to the frequency has a maximum sound absorption peak in the region of a frequency of 850 Hz or more and 3000 Hz or less.

Effects of the Invention

[0007] The sound-absorbing material of the present invention is a laminate having a base material, a porous layer having vertically long holes extending in the thickness direction of the porous layer on one surface side of the base material, and a ventilation layer on the other surface side of the base material. By arranging the porous layer side on the sound source side and using it, excellent sound-absorbing characteristics can be exhibited for sounds of a wide range of frequencies from the low-frequency range to the high-frequency range.

Brief Description of Drawings

[0008]

Figure 1

Figure 2

Figure 3

Embodiments for Carrying Out the Invention

[0009] The sound-absorbing material according to the present invention is a laminate having a base material, a porous layer having vertically long holes extending in the thickness direction of the porous layer on one surface side of the base material, and a ventilation layer on the other surface side of the base material. And, the sound-absorbing material of the present invention needs to be arranged and used so that the porous layer side becomes the sound source side. By arranging the porous layer on the sound source side, the incident sound reaches the base material through the vertically long holes extending in the thickness direction in the porous layer and is absorbed by membrane vibration. At this time, by arranging the ventilation layer on the other surface side of the base material (that is, the side opposite to the sound source), excellent sound-absorbing characteristics can be exhibited for sounds of a wide range of frequencies from the low-frequency range to the high-frequency range. Incidentally, when the above laminate is arranged and used so that the ventilation layer side becomes the sound source side, although it shows sound-absorbing characteristics for sounds in the relatively high-frequency range, unexpectedly, it has been found that the sound-absorbing characteristics for sounds in the relatively low-frequency range are not exhibited. This will be demonstrated in the examples.

[0010] Hereinafter, the sound-absorbing material of the present invention will be described in detail.

[0011] (Base material) The base material is preferably, for example, a woven fabric, a knitted fabric, or a non-woven fabric formed using fibers, among which a knitted fabric or a non-woven fabric is more preferable.

[0012] The type of fiber constituting the base material is not particularly limited and may be either an inorganic fiber or an organic fiber. When heat resistance is required for the sound-absorbing material, it is preferable to use an inorganic fiber. When heat resistance is not so required and cost is emphasized, it is preferable to use an organic fiber.

[0013] As the inorganic fiber, for example, metal fiber, glass fiber, etc. can be used. As the organic fiber, for example, natural fibers such as cotton, hemp, and silk, regenerated fibers such as rayon, cupra, and tencel, and synthetic fibers such as polyester, nylon, and polyamide can be used, and those in which these are blended or interwoven may also be used. Among these, it is more preferable to use an organic fiber in terms of affinity with the porous layer and versatility, and more preferably a synthetic fiber.

[0014] The specific gravity of the base material is preferably, for example, 0.15 or more and 0.35 or less. The specific gravity of the base material is more preferably 0.18 or more, still more preferably 0.20 or more, more preferably 0.33 or less, and still more preferably 0.30 or less. The specific gravity of the base material may be calculated by unit conversion from the basis weight measured according to JIS L1096 Method A and the thickness.

[0015] The thickness of the base material is not particularly limited and may be adjusted according to the strength required for the sound-absorbing material. For example, it is preferably 0.1 mm or more and 1.1 mm or less. The thickness of the base material is more preferably 0.3 mm or more, still more preferably 0.4 mm or more, more preferably 1.0 mm or less, and still more preferably 0.9 mm or less.

[0016] The base material preferably has air permeability. The base material permeates air and moisture, and the air permeability measured by JIS L1096 is 2.0 cm 3 / cm 2 ·sec or more and 80.0 cm 3 / cm 2·It is preferably satisfied within ·sec or less.

[0017] (porous layer) The porous layer has longitudinally extending pores extending in the thickness direction of the porous layer. For example, spherical pores are not included in the longitudinally extending pores. The longitudinally extending pores may or may not communicate from one side to the other side of the porous layer.

[0018] The longitudinally extending pores formed in the porous layer preferably have a ratio of the length of the pore to the diameter of the pore (length of the pore / diameter of the pore; hereinafter referred to as the aspect ratio) of 1.6 or more. The aspect ratio of the longitudinally extending pores is more preferably 1.7 or more, and even more preferably 1.8 or more. The upper limit of the aspect ratio of the longitudinally extending pores is not particularly limited, but for example, 4 or less is preferable, and more preferably 3.5 or less. The aspect ratio of the longitudinally extending pores may be calculated based on a photograph taken by observing a cross-section in the thickness direction of the porous layer with a scanning electron microscope. Note that the pore diameter means the maximum diameter of the pore. Also, the pore length means the length of the pore in the thickness direction of the porous layer.

[0019] The porous layer can be formed, for example, by a wet coagulation method. The wet coagulation method is a method of immersing a substrate coated with a solution in which a resin is dissolved in a solvent into a coagulating liquid, and replacing (phase-converting) the solvent contained in the solution with the coagulating liquid to solidify the resin on the substrate while making the resin porous. The wet coagulation method will be described in detail later.

[0020] The specific gravity of the porous layer is preferably, for example, 0.15 or more and 1.0 or less. The specific gravity of the porous layer is more preferably 0.20 or more, even more preferably 0.25 or more, more preferably 0.7 or less, and even more preferably 0.6 or less. The specific gravity of the porous layer may be calculated by unit conversion from the basis weight measured according to JIS L1096 Method A to the thickness.

[0021] There may or may not be openings on the surface of the porous layer, but it is preferable that there are openings.

[0022] The type of resin constituting the porous layer is not particularly limited. For example, it includes polyesters [such as polyethylene terephthalate, polyethylene naphthalate, etc.], polyurethanes, polyacrylates, polycarbonates, polylactic acid, polyvinyl alcohol, polyvinylidene fluoride, polysulfones, polyethersulfones, polyamides, polyimides, polyetherimides, polyamideimides, polybenzimidazoles, etc. Among these, at least one selected from the group consisting of polyurethane, polyvinylidene fluoride, polyethersulfone, polyimide, and polyamideimide is preferred, and polyurethane is more preferred.

[0023] The porous layer may contain other components such as additives, pore regulators, fillers, etc. as necessary for improving physical properties such as durability, improving functions such as air permeability, imparting chemical resistance, antistatic properties, heat resistance, flame retardancy, and designability, as long as the properties of the sound-absorbing material are not impaired. Examples of additives for improving physical properties include acrylic beads, ceramic beads, etc. Examples of additives for imparting heat resistance include isocyanate-based crosslinking agents, etc. Examples of additives for imparting flame retardancy include flame retardants. The flame retardant can be a liquid or a solid. Specifically, conventionally known flame retardants such as halogen-based, halogen-antimony-based, phosphate ester-based, phosphorus-nitrogen-based, magnesium hydroxide, aluminum hydroxide, and silicon-based flame retardants can be used. Examples of additives for imparting designability include colorants. It is preferable to select a conventionally known colorant suitable for the wet coagulation method.

[0024] The average thickness of the porous layer is preferably 0.1 mm or more and 0.8 mm or less. By setting the average thickness of the porous layer within such a range, the sound absorption performance can be improved, and moreover, the air permeability and moisture permeability can also be made good. The average thickness of the porous layer is more preferably 0.15 mm or more, still more preferably 0.2 mm or more, more preferably 0.7 mm or less, and still more preferably 0.6 mm or less. The thickness of the porous layer may be measured by observing a cross-section in the thickness direction of the sound-absorbing material with a scanning electron microscope, and the average value of the thicknesses measured at any three locations may be taken as the average thickness.

[0025] A surface treatment layer may be formed on the surface of the porous layer. Examples of the surface treatment layer include resin layers such as polyurethane, polyvinylidene fluoride, polyethersulfone, polyimide, and polyamideimide.

[0026] For example, pattern processing may be applied to the surface of the porous layer and / or the surface of the surface treatment layer. By applying pattern processing, the design property becomes good. Examples of the types of patterns include leather grain pattern, diamond pattern, triangular pattern, pore pattern, etc.

[0027] (Ventilation layer) The ventilation layer permeates air and moisture, and has an air permeability of 2.0 cm 3 / cm 2 ·sec or more and 80.0 cm 3 / cm 2 ·sec or less.

[0028] The specific gravity of the ventilation layer is preferably, for example, 0.01 or more and 0.1 or less. The specific gravity of the ventilation layer is more preferably 0.013 or more, still more preferably 0.015 or more, more preferably 0.08 or less, and still more preferably 0.06 or less. The specific gravity of the ventilation layer may be calculated by unit conversion from the basis weight measured according to JIS L1096 Method A and the thickness.

[0029] The specific gravity of the ventilation layer may be the same as that of the porous layer, but it is preferably different from the specific gravity of the porous layer. When the specific gravity of the ventilation layer is different from that of the porous layer, the specific gravity of the ventilation layer is preferably smaller than that of the porous layer (i.e., the specific gravity of the porous layer is larger than that of the ventilation layer). The specific gravity of the porous layer with respect to the specific gravity of the ventilation layer is preferably, for example, 8 times or more and 30 times or less. The specific gravity of the porous layer with respect to the specific gravity of the ventilation layer is more preferably 10 times or more, still more preferably 12 times or more, and more preferably 28 times or less, still more preferably 26 times or less.

[0030] The form of the ventilation layer is not particularly limited, and for example, non-woven fabric or foam is preferable. Non-woven fabric includes not only those formed by adhering or intertwining fibers by heat, mechanical, or chemical action into a cloth shape, but also felt made by compressing a mixture of animal hairs such as sheep and camel, and recycled fibers into a sheet shape. Among these, foam is preferable.

[0031] The ventilation layer may be porous, but in the case of being porous, it does not have vertically elongated holes extending in the thickness direction of the ventilation layer. The vertically elongated holes extending in the thickness direction of the ventilation layer mean holes with a ratio of the length of the hole to the diameter of the hole (hole length / hole diameter. aspect ratio) of 1.6 or more. Note that the ventilation layer may have holes with an aspect ratio of less than 1.6. Note that the diameter of the hole means the maximum diameter of the hole. Also, the length of the hole means the length of the hole in the thickness direction of the porous layer.

[0032] The ventilation layer is preferably composed of a resin. The type of resin constituting the ventilation layer is not particularly limited. For example, polyester [such as polyethylene terephthalate, polyethylene naphthalate, etc.], polyurethane, polyacrylate, polycarbonate, polylactic acid, polyvinyl alcohol, polyvinyl acetate, polyvinylidene fluoride, polysulfone, polyethersulfone, polyamide, polyimide, polyetherimide, polyamideimide, polybenzimidazole, polystyrene, polyethylene, polypropylene, epoxy, melamine, ethylene propylene rubber, ethylene propylene diene rubber, chloroprene rubber, etc. may be mentioned. Among these, at least one selected from the group consisting of polyurethane, polyvinylidene fluoride, polyethersulfone, polystyrene, polyethylene, and polypropylene is preferable, and more preferably polyurethane.

[0033] The average thickness of the ventilation layer is preferably 7 mm or more and 15 mm or less. By setting the average thickness of the ventilation layer within such a range, the sound absorption performance can be improved, and moreover, the ventilation and moisture permeability can also be made good. The average thickness of the ventilation layer is more preferably 8 mm or more, still more preferably 9 mm or more, more preferably 13 mm or less, and still more preferably 12 mm or less.

[0034] The thickness of the ventilation layer may be measured by observing the cross-section in the thickness direction of the sound absorption material with a scanning electron microscope, and the average value of the thicknesses measured at any three locations may be taken as the average thickness.

[0035] (Sound absorption material) The sound absorption material of the present invention has a porous layer, a base material, and a ventilation layer laminated in this order, and is arranged and used such that the porous layer side faces the sound source side.

[0036] For the sound absorption material, the specific gravity of the base material is relatively larger than that of the ventilation layer, and it is preferable that the specific gravity of the base material is the same as that of the porous layer or the specific gravity of the porous layer is relatively larger than that of the base material. More preferably, the specific gravity of the base material is relatively larger than that of the ventilation layer, and the specific gravity of the porous layer is relatively larger than that of the base material.

[0037] In the cross-section in the thickness direction of the sound-absorbing material, it is preferable that the average porosity of the ventilation layer is larger than the average porosity of the porous layer.

[0038] The porosity of the porous layer can be calculated as the ratio of the length of pores in a line segment with a length of 500 μm parallel to the base material at the d1 / 2 position when observing the cross-section in the thickness direction of the porous layer with a scanning electron microscope and setting the thickness of the porous layer as d1. The average value of the porosity measured at any three locations can be taken as the average porosity.

[0039] The porosity of the ventilation layer can be calculated as the ratio of the length of pores in a line segment with a length of 1 mm parallel to the base material at the d2 / 2 position when observing the cross-section in the thickness direction of the ventilation layer with a scanning electron microscope and setting the thickness of the ventilation layer as d2. The average value of the porosity measured at any three locations can be taken as the average porosity.

[0040] The sound-absorbing material has a normal incidence sound absorption rate measured according to the test method of JIS A1405-2 of 0.2 or more in the frequency range of 850 Hz or more and 5000 Hz or less, and has excellent sound absorption characteristics for sounds of a wide range of frequencies from a low-frequency range of about 850 Hz to a high-frequency range of about 5000 Hz. It is more preferable that the normal incidence sound absorption rate is 0.3 or more in the frequency range of 850 Hz or more and 5000 Hz or less. Also, for the sound-absorbing material, it is preferable that the normal incidence sound absorption rate is 0.3 or more in the frequency range of 1000 Hz or more and 5000 Hz or less. Further, for the sound-absorbing material, it is preferable that the normal incidence sound absorption rate is 0.8 or more in the frequency range of 1600 Hz or more and 2100 Hz or less.

[0041] When measuring the normal incidence sound absorption rate of the sound-absorbing material and drawing a curve with respect to the frequency, it is preferable that the curve has a maximum sound absorption peak in the region of 850 Hz or more and 3000 Hz or less. By having a maximum sound absorption peak in this region, excellent sound absorption characteristics can be shown for sounds in a relatively low-frequency range.

[0042] The total thickness of the sound-absorbing material is preferably, for example, 8 mm or more and 15 mm or less. The total thickness of the sound-absorbing material is more preferably 9 mm or more, still more preferably 10 mm or more, and more preferably 14 mm or less, still more preferably 13 mm or less.

[0043] The sound-absorbing material can be used, for example, to absorb sound from a noise source in a building, an electrical product, a vehicle, etc. and reduce noise. Specifically, it can be suitably used as an interior material for a room, an interior of an aircraft, and an interior material of a vehicle.

[0044] Next, a method for manufacturing the sound-absorbing material of the present invention will be described. The sound-absorbing material of the present invention includes a step of bringing a solution in which a resin is dissolved in a solvent into contact with one surface of a base material (hereinafter sometimes referred to as a solution contact step), a step of making the resin porous by removing the solvent (hereinafter sometimes referred to as a porosification step), and a step of forming a ventilation layer on the other surface of the base material (hereinafter sometimes referred to as a ventilation layer formation step). Hereinafter, each step will be described in detail.

[0045] [Solution Contact Step] In the solution contact step, a solution in which a resin is dissolved in a solvent is brought into contact with one surface of a base material.

[0046] The amount of the above solution adhered to one surface of the base material is preferably, for example, 900 g / m 2 or more and 1600 g / m 2 or less. By setting the adhesion amount of the solution to 900 g / m 2 or more, the thickness of the formed porous layer can be increased, so that the strength can be ensured. The adhesion amount of the solution is more preferably 950 g / m 2 or more, still more preferably 1000 g / m 2 or more. On the other hand, if the adhesion amount of the solution exceeds 1600 g / m 2 , the thickness of the formed porous layer becomes too thick, so that the air permeability and moisture permeability deteriorate, and the pressure loss may increase. Therefore, the adhesion amount of the solution is preferably 1600 g / m 2 or less, more preferably 1500 g / m 2More preferably, it is 1400 g / m 2 or less below.

[0047] As the resin to be dissolved in the solvent, those exemplified above as the resin constituting the porous layer can be used. Specifically, at least one selected from the group consisting of polyester, polyurethane, polyacrylate, polycarbonate, polylactic acid, polyvinyl alcohol, polyvinylidene fluoride, polysulfone, polyethersulfone, polyamide, polyimide, polyetherimide, polyamideimide, and polybenzimidazole can be used.

[0048] The concentration of the resin to be dissolved in the solution can be arbitrarily set according to the solubility of the resin in the solvent used. For example, it is preferably 5% by mass or more and 60% by mass or less. By setting the resin concentration to 5% by mass or more, the adhesion between the porous layer and the base material can be enhanced, and it is possible to prevent the porous layer from peeling off from the base material during use. The resin concentration is more preferably 15% by mass or more, and even more preferably 20% by mass or more. On the other hand, by setting the resin concentration to 60% by mass or less, the ratio of pores to the volume of the porous layer (hereinafter sometimes referred to as porosity) can be increased, and the air permeability and moisture permeability of the sound-absorbing material can be enhanced. In addition, since the viscosity of the solution can be lowered, a uniform porous layer can be obtained. Further, by lowering the viscosity of the solution, it becomes easier to remove the solvent in the subsequent porosification process, and the porosification of the resin becomes easier. The resin concentration is more preferably 55% by mass or less, and even more preferably 50% by mass or less.

[0049] As the solvent for dissolving the resin (hereinafter sometimes referred to as the first solvent), an organic solvent commonly used in the wet coagulation method can be used. For example, at least one selected from the group consisting of aprotic polar solvents, halogen-based solvents, ketone-based solvents, cyclic ether-based solvents, and aromatic organic solvents can be used. Specifically, aprotic polar solvents such as dimethylformamide, dimethylacetamide, dimethyl sulfoxide, and N-methylpyrrolidone; halogen-based solvents such as dichloromethane and chloroform; ketone-based solvents such as dimethyl ketone and methyl ethyl ketone; cyclic ether-based solvents such as tetrahydrofuran and dioxane; aromatic organic solvents such as toluene and xylene; etc. can be used. These solvents may be used as a mixture of two or more. Among the above organic solvents, it is preferable to use aprotic polar solvents in terms of the impact on the environment, processability in the wet coagulation method, simplicity, etc.

[0050] To the above solution, other components such as additives, pore regulators, fillers, etc. can be added as necessary for improving physical properties such as durability, improving functions such as air permeability, imparting chemical resistance, antistatic properties, heat resistance, imparting flame retardancy, imparting design properties, etc., within the range that does not impair the properties of the sound-absorbing material. Examples of the pore regulator for adjusting the shape of pores include nonionic, cationic, and anionic surfactants, alcohol-based solvents, hydrophilic polymer additives such as polyethylene oxide, and hydrophobic additives such as paraffin-based oils and aromatic solvents. Two or more kinds of the above pore regulators may be used. The amount of the pore regulator may be at a commonly used level. For example, it is preferably 0.1 part by mass or more and 10 parts by mass or less based on the mass of the entire solution.

[0051] Examples of the method for bringing the above solution into contact with one surface of the substrate include comma coating method, die coating method, doctor knife coating method, reverse roll coating method, gravure coating method, bar coating method, etc. These methods are suitable for coating a low-viscosity solution. Among these, it is more preferable to bring it into contact by the comma coating method or the die coating method.

[0052] Porous Formation Process In the porous formation process, the resin is made porous by removing the solvent from the solution adhered to the substrate, and a porous layer having vertically extending holes extending in the thickness direction of the porous layer is formed. As a result, the substrate and the porous layer will be directly connected.

[0053] Examples of the method for removing the solvent from the solution adhered to the substrate include heating to a temperature equal to or higher than the boiling point of the solvent, and the wet coagulation method, etc., and the wet coagulation method is preferred. In the wet coagulation method, the substrate with the solution adhered thereto is brought into contact with a second solvent having compatibility with the above solvent (first solvent), whereby the first solvent and the second solvent are replaced, and the resin can be made porous. At this time, the second solvent can solidify the resin by using a solvent that does not dissolve the resin or is difficult to dissolve the resin.

[0054] As the second solvent, for example, it is preferable to use water or an alcohol-based solvent, and two or more kinds may be mixed and used. As the alcohol-based solvent, for example, methanol, ethanol, etc. can be used.

[0055] Prior to bringing the substrate with the above solution adhered thereto into contact with the second solvent, it may be brought into contact with a mixed solution of the first solvent and the second solvent. By bringing it into contact with the mixed solution of the first solvent and the second solvent and then bringing it into contact with the second solvent, the first solvent can be surely replaced with the second solvent, so that the first solvent does not remain and the porous formation of the resin can be promoted. As the mixed solution of the first solvent and the second solvent, for example, it is preferable to use a mixed solution of an aprotic polar solvent and water.

[0056] After forming the porous layer, a surface treatment layer may be formed. Examples of the surface treatment layer include resin layers such as the above-mentioned polyurethane, polyvinylidene fluoride, polyethersulfone, polyimide, polyamideimide, etc.

[0057] In addition, pattern processing may be performed on the surface of the porous layer and / or the surface of the surface treatment layer. Examples of the method for performing pattern processing include, for example, etching. As the etching solution, a solvent that dissolves the porous layer and / or the surface treatment layer may be used.

[0058] [Ventilation layer forming step] In the ventilation layer forming step, a ventilation layer is formed on the other surface of the base material, whereby a sound absorbing material is obtained. The method for forming the ventilation layer on the other surface of the base material is not particularly limited, and the base material and the pre-formed ventilation layer may be bonded and connected.

[0059] Examples of the method of bonding and connecting include, for example, frame lamination and bonding using an adhesive. When bonding using an adhesive, for example, a breathable double-sided tape may be used, or instead of applying the adhesive to the entire bonding surface, the adhesive may be applied partially to ensure breathability.

Example

[0060] Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited by the following examples, and it is of course possible to make modifications within the scope that conforms to the above and below gists and implement them, and all of them are included in the technical scope of the present invention. In the examples, unless otherwise specified, “%” and “parts” are based on mass.

[0061] (Example 1) In Example 1, a porous layer was formed on one surface side of the base material by the wet coagulation method, and a ventilation layer was formed on the other surface side of the base material. As the base material, 100% polyester tricot was used. The air permeability of the base material was 54.4 cm 3 / cm 2 ·sec.

[0062] First, 100 parts of "Resamin CU9443" manufactured by Dainichi Seika Chemical Industry Co., Ltd., 5 parts of "Pecoframe STC" manufactured by Clariant Japan, 8 parts of barium sulfate, 5 parts of "Seika Seven BS780(S)" manufactured by Dainichi Seika Chemical Industry Co., Ltd., and 130 parts of dimethylformamide were stirred at 2000 rpm using a high-speed agitator disperser to prepare a polyurethane solution. The prepared polyurethane solution was cast onto a substrate using a comma coater (registered trademark) manufactured by Hirano Texeed so that the wet coat amount was 1100 g / m 2 Then, the substrate coated with the polyurethane solution was immersed in a 10% aqueous solution of dimethylformamide at 25°C for about 300 seconds to remove dimethylformamide from the polyurethane solution adhered to the substrate while coagulating the polyurethane. Next, after immersing in warm water at 40°C for 15 minutes, it was squeezed with a mangle at a pressure of 0.4 MPa and dried in an oven at 140°C. As a result, a structure in which the substrate and the porous layer were laminated was obtained.

[0063] Next, 100 parts of "Crisbon NB-637N" manufactured by DIC Corporation (formerly Dainippon Ink and Chemicals, Inc.), 100 parts of dimethylformamide, and 100 parts of methyl ethyl ketone were mixed to prepare an etching solution. The prepared etching solution was applied to the surface of the porous layer of the above structure using a gravure coater and then dried in an oven at 140°C to etch the surface of the porous layer and form a pattern. The pattern was a leather-like pitted pattern. Thereby, a patterned structure was obtained in which the dissolved part had an open surface while having a leather-like design on the surface of the porous layer.

[0064] Next, a polyether-based soft urethane foam material (Clarafoam manufactured by Kurabo Industries Ltd.) with a thickness of 10 mm as a ventilation layer was laminated and bonded to the surface of the substrate on the side opposite to the side where the porous layer was formed in the above patterned structure by frame lamination, and a laminate a having a porous layer on one surface side of the substrate and a ventilation layer on the other surface side was manufactured. The air permeability of the polyether-based soft urethane foam material was 75.5 cm 3 / cm 2 ·sec. The obtained laminate a was evaluated for various physical properties according to the following procedure. The results are shown in Table 1.

[0065] (1) Total thickness of the laminate Using a dial thickness gauge, the thicknesses of three locations of laminate a were measured, and the average value was taken as the total thickness. (2) Average thickness of the porous layer and the ventilation layer A 100 mm square test piece was cut out from laminate a. Three locations randomly extracted from the test piece were cut while being frozen with liquid nitrogen, and the cross-section in the thickness direction was observed at a magnification of 150 times with a scanning electron microscope manufactured by Hitachi High-Technologies Corporation, and a photograph was taken. Based on the photographed image, the thicknesses of three locations each of the porous layer and the ventilation layer were measured, and the average value was calculated. (3) Shape of pores in the porous layer Using a scanning electron microscope, the cross-section in the thickness direction of laminate a was observed at a magnification of 50 times, and a photograph was taken. Based on the photographed image, it was evaluated whether vertically long pores extending in the thickness direction of the porous layer were formed in the porous layer. Also, when the vertically long pores were formed, the ratio (aspect ratio) of the length of the vertically long pores to the diameter of the vertically long pores was measured. The diameter of the vertically long pores means the maximum diameter of the vertically long pores. Also, the length of the vertically long pores means the length of the vertically long pores in the thickness direction of the porous layer. (4) Average porosity of the porous layer and the ventilation layer For the porosity of the porous layer, the cross-section in the thickness direction of the porous layer was observed at a magnification of 150 times using a scanning electron microscope. When the thickness of the porous layer was d1, a line segment 500 μm long was drawn parallel to the base material at the d1 / 2 position, and the porosity with respect to the line segment 500 μm long at the d1 / 2 position was measured three times each, and the average value was calculated. For the porosity of the ventilation layer, the cross-section in the thickness direction of the ventilation layer was observed at a magnification of 50 times using a scanning electron microscope. When the thickness of the ventilation layer was d2, a line segment 1 mm long was drawn parallel to the base material at the d2 / 2 position, and the porosity with respect to the line segment 1 mm long at the d2 / 2 position was measured three times each, and the average value was calculated. (5) Specific gravity of the porous layer, the base material, and the ventilation layer The specific gravities of the porous layer, the base material, and the ventilation layer were calculated by converting the measured basis weight according to JIS L1096 Method A into units with thickness. (6) Air permeability of laminate a The air permeability of the laminate a was measured using an air permeability tester (model: KES-F8) manufactured by Kato Tech Co., Ltd. (7) Sound absorption characteristics The normal incidence sound absorption rate of the laminate a was measured in accordance with JIS A1405-2 (normal incidence sound absorption rate), and the sound absorption characteristics were evaluated based on the measurement results. The measurement was performed with the porous layer side of the laminate a placed on the sound source side. The relationship between the frequency and the normal incidence sound absorption rate is shown in FIG. 1.

[0066] (Example 2) In Example 2, in the same manner as in Example 1 above, a porous layer was formed on one surface side of the base material by the wet coagulation method, and a ventilation layer was formed on the other surface side of the base material. In Example 2, a 100% polyester non-woven fabric was used as the base material. The air permeability of the base material was 78.1 cm 3 / cm 2 ·sec.

[0067] The polyurethane solution prepared in Example 1 above was cast onto the base material using a comma coater (registered trademark) manufactured by Hirano Texeed Co., Ltd. so that the WET coat amount was 1300 g / m 2 Then, the base material coated with the polyurethane solution was immersed in a 10% aqueous solution of dimethylformamide at 25°C for about 360 seconds to remove dimethylformamide from the polyurethane solution adhered to the base material while coagulating the polyurethane. Next, after immersing in warm water at 40°C for 20 minutes, it was squeezed with a mangle at a pressure of 0.4 MPa and dried in an oven at 140°C. As a result, a structure in which the base material and the porous layer were laminated was obtained.

[0068] Next, the etching solution prepared in Example 1 above was applied to the surface of the porous layer of the above structure using a gravure coater, and then dried in an oven at 140°C to form a pattern on the surface of the porous layer by etching. The pattern was a leather-like hair hole pattern. Thereby, a patterned structure having a leather-like design on the surface of the porous layer and with the dissolved portions having surface openings was obtained.

[0069] Next, on the surface of the base material on the side opposite to the side where the porous layer in the above-mentioned patterned structure is formed, a polyether-based soft urethane foam material (Clarafoam manufactured by Kurabo Industries Ltd.) with a thickness of 10 mm as a ventilation layer was laminated by frame lamination to produce a laminate b having a porous layer on one surface side of the base material and a ventilation layer on the other surface side. Using the laminate b instead of the laminate a in Example 1 above, various physical properties were evaluated in the same procedure as in Example 1 above. The results are shown in Table 1. The sound absorption characteristics were evaluated by measuring the normal incidence sound absorption rate with the porous layer side of the laminate b facing the sound source side.

[0070] (Comparative Example 1) In Comparative Example 1, a laminate c was produced by forming a porous layer on both sides of the base material by the wet coagulation method. That is, in Example 1 above, on the surface of the base material on the side opposite to the side where the porous layer in the above-mentioned patterned structure is formed, the polyurethane solution prepared in Example 1 was cast using a wire bar so that the WET coat amount was 1100 g / m 2 Then, the base material with the polyurethane solution was immersed in a 10% aqueous solution of dimethylformamide at 25°C for about 400 seconds to remove dimethylformamide from the polyurethane solution adhered to the base material while coagulating the polyurethane. Next, after immersing in warm water at 40°C for 20 minutes, it was squeezed with a mangle at a pressure of 0.4 MPa and dried in an oven at 140°C. As a result, a laminate c having porous layers on both sides of the base material was obtained. Using the laminate c instead of the laminate a in Example 1 above, various physical properties were evaluated in the same procedure as in Example 1 above. The results are shown in Table 1.

[0071] (Comparative Example 2) In Comparative Example 2, an air-permeable layer was formed on both sides of the base material to produce laminate d. In Comparative Example 2, 100% polyester tricot was used as the base material. On the surface of the base material, a polyether-based flexible urethane foam material with a thickness of 10 mm (Clarafoam manufactured by Kurabo Industries Ltd.) was laminated by frame lamination to produce a structure in which the base material and the polyether-based flexible urethane foam material were laminated. Next, on the surface of the base material on the side opposite to the side where the polyether-based flexible urethane foam material was laminated in the above structure, a polyether-based flexible urethane foam material with a thickness of 10 mm (Clarafoam manufactured by Kurabo Industries Ltd.) was laminated by frame lamination to produce laminate d having air-permeable layers on both sides of the base material. Using laminate d instead of laminate a in Example 1 above, various physical properties were evaluated in the same procedure as in Example 1 above. The results are shown in Table 1.

[0072] (Comparative Example 3) In Comparative Example 3, laminate a produced in Example 1 above was prepared, and the vertical incidence sound absorption rate was measured with the air-permeable layer side of laminate a as the sound source side to evaluate the sound absorption characteristics.

[0073] (Comparative Example 4) In Comparative Example 4, an air-permeable layer was formed on one surface side of the base material to produce laminate e. In Comparative Example 4, 100% polyester tricot was used as the base material. On the surface of the base material, a polyether-based flexible urethane foam material with a thickness of 10 mm (Clarafoam manufactured by Kurabo Industries Ltd.) was laminated by frame lamination to produce laminate e in which the base material and the polyether-based flexible urethane foam material were laminated. Using laminate e instead of laminate a in Example 1 above, various physical properties were evaluated in the same procedure as in Example 1 above. The results are shown in Table 1. The sound absorption characteristics were evaluated by measuring the vertical incidence sound absorption rate with the base material side of laminate e as the sound source side.

[0074] (Comparative Example 5) In Comparative Example 5, a polyether-based flexible urethane foam material with a thickness of 10 mm (Clarafoam manufactured by Kuraray Co., Ltd.) was used as a test piece as it was. Instead of the laminate a in Example 1 above, a polyether-based flexible urethane foam material was used, and various physical properties were evaluated in the same procedure as in Example 1 above. The results are shown in Table 1.

[0075]

Table 1

[0076] The following considerations can be made from Table 1 and Figure 1. The laminate a obtained in Example 1 and the laminate b obtained in Example 2 both have, on one surface side of the base material, a porous layer having vertically elongated holes extending in the thickness direction of the porous layer, and on the other surface side of the base material, a ventilation layer, and are sound-absorbing materials that satisfy the requirements defined in the present invention. Also, a leather-like hair hole pattern was formed on the surface of the porous layer, and the design property was also good. As is clear from Figure 1, the curve based on Example 1 (the solid line with plot points being black squares) and the curve based on Example 2 (the solid line with plot points being black circles) both had a maximum sound absorption peak in the frequency range of 850 Hz to 3000 Hz. Also, in the frequency range of 850 Hz to 5000 Hz, the normal incidence sound absorption rate was 0.2 or more, and the sound absorption characteristics were good. Also, in the frequency range of 1600 Hz to 2000 Hz, the normal incidence sound absorption rate was 0.8 or more. Also, in the frequency range of 3000 Hz to 5000 Hz, the normal incidence sound absorption rate was 0.3 or more. Although the mechanism of exhibiting sound absorption characteristics over a wide range of frequencies while having a high sound absorption rate in the low-frequency sound range has not been elucidated, it is considered that while having sound absorption performance due to membrane vibration, a resonance phenomenon occurs in the holes existing on the surface of the porous layer and in the vertically elongated holes inside, and the sound absorption performance of the resonance structure type and the sound absorption performance of the porous body type are also combined, and they show excellent sound absorption characteristics that have never been seen before while mutually influencing each other.

[0077] Regarding the laminate a obtained in Example 1, a photograph of a cross-section in the thickness direction of the laminate a observed and taken with a scanning electron microscope at a magnification of 150 times is shown in FIG. 2, and a photograph of the laminate a observed and taken at a magnification of 50 times is shown in FIG. 3. FIG. 2 is a photograph of the porous layer and the base material portion, and FIG. 3 is a photograph of the ventilation layer.

[0078] The laminate c obtained in Comparative Example 1 has porous layers on both sides of the base material and is an example that does not satisfy the requirements defined in the present invention. As is clear from FIG. 1, the curve based on Comparative Example 1 (the dotted line with plot points being white triangles) did not have a maximum sound absorption peak in the frequency range of 850 Hz to 3000 Hz. Also, the normal incidence sound absorption rate in the frequency range of 850 Hz to 5000 Hz was less than 0.2.

[0079] The laminate d obtained in Comparative Example 2 has ventilation layers on both sides of the base material and is an example that does not satisfy the requirements defined in the present invention. As is clear from FIG. 1, the curve based on Comparative Example 2 (the dotted line with plot points being black diamonds) did not have a maximum sound absorption peak in the frequency range of 850 Hz to 3000 Hz. Also, the normal incidence sound absorption rate in the frequency range of 850 Hz to 5000 Hz was less than 0.2.

[0080] Comparative Example 3 uses the laminate a that satisfies the requirements defined in the present invention manufactured in Example 1 above, but is an example in which the ventilation layer side is arranged on the sound source side. As is clear from FIG. 1, the curve based on Comparative Example 3 (the dotted line with plot points being white circles) did not have a maximum sound absorption peak in the frequency range of 850 Hz to 3000 Hz. Also, the normal incidence sound absorption rate in the frequency range of 850 Hz to 5000 Hz was less than 0.2.

[0081] The laminate e obtained in Comparative Example 4 does not form a porous layer and is an example that does not satisfy the requirements defined in the present invention. As is clear from FIG. 1, the curve based on Comparative Example 4 (the dotted line with plot points being black triangles) did not have a maximum sound absorption peak in the frequency range of 850 Hz to 3000 Hz. Also, the normal incidence sound absorption rate in the frequency range of 850 Hz to 5000 Hz was less than 0.2.

[0082] Comparative Example 5 is an example using only the ventilation layer. As is clear from FIG. 1, the curve based on Comparative Example 5 (the dotted line with plot points being white squares) did not have a maximum sound absorption peak in the frequency range of 850 Hz to 3000 Hz. Also, the normal incidence sound absorption rate at frequencies of 850 Hz to 5000 Hz was less than 0.2.

Claims

Claim 1 a base material, a porous layer having vertically elongated holes extending in the thickness direction on one surface side of the base material, a ventilation layer on the other surface side of the base material, and has, the porous layer side is the sound source side, a sound absorbing material characterized in that the normal incidence sound absorption rate measured according to the test method of JIS A1405-2 is 0.3 or more at frequencies of 850 Hz or more and 5000 Hz or less. Claim 2 The sound absorbing material according to claim 1, wherein the ratio of the length of the hole to the diameter of the hole (hole length / hole diameter) of the vertically elongated hole is 1.6 or more. Claim 3 The sound absorbing material according to claim 1 or 2, wherein in the cross section in the thickness direction of the sound absorbing material, the average porosity of the ventilation layer is larger than the average porosity of the porous layer. Claim 4 The sound absorbing material according to any one of claims 1 to 3, wherein the porous layer is formed by a wet solidification method. Claim 5 The sound absorbing material according to any one of claims 1 to 4, wherein the specific gravity of the porous layer is larger than the specific gravity of the ventilation layer. Claim 6 The sound absorbing material according to any one of claims 1 to 5, wherein the specific gravity of the porous layer is 0.15 or more and 1.0 or less. Claim 7 The sound absorbing material according to any one of claims 1 to 6, wherein the specific gravity of the ventilation layer is 0.01 or more and 0.1 or less. Claim 8 The sound absorbing material according to any one of claims 1 to 7, wherein there are openings on the surface of the porous layer. Claim 9 The sound absorbing material according to any one of claims 1 to 8, wherein the ventilation layer is a foam. Claim 10 The sound absorbing material according to any one of claims 1 to 9, wherein the curve showing the normal incidence sound absorption rate with respect to the frequency has a maximum sound absorption peak in the region of 850 Hz or more and 3000 Hz or less.

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