Sound absorbing material and sound absorbing panel

Abstract

To provide a sound absorbing material and a sound absorbing panel which have a small amount of carbon dioxide emission during manufacturing or the like and a high sound absorption coefficient.SOLUTION: The sound absorbing material 1 includes inner cotton 2 and a skin material 3. The basis weight of the sound-absorbing material is 2000g / m2 or less. The ratio of the total surface area (m2 / m2) per unit area of the inner cotton to the total surface area (m2 / m2) per unit area of the skin material is less than 10. The thickness of the inner cotton is not less than 40mm. The bulk density of the batting is less than 37kg / m3. The padding is a nonwoven fabric including thermoplastic resin hollow fibers and thermoplastic resin solid fibers having an average fiber diameter different from an average fiber diameter of the thermoplastic resin hollow fibers. The total surface area of the outer diameters of the fibers constituting the padding per unit area of the padding is 160m2 / m2 super 270m2 / m2 or less. The skin material is a nonwoven fabric containing thermoplastic resin fibers.SELECTED DRAWING: Figure 1

Description

[Technical Field]

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

[0002] As environmental measures along Shinkansen lines and in railroad car parking areas, soundproof walls are being installed, soundproof walls are being raised, and sound-absorbing panels are being installed. Sound-absorbing panels are installed on the track side of soundproof walls and are equipped with sound-absorbing material inside to reduce various types of noise. Therefore, there is a demand for sound-absorbing materials and sound-absorbing panels that have better noise control functions.

[0003] Patent Document 1 discloses a composite sound-absorbing material (hereinafter also referred to as "sound-absorbing material"). The sound-absorbing material is composed of two or more layers including a base material (hereinafter also referred to as "filling") and a skin material. The skin material is arranged as the outermost layer. The surface area per unit area of ​​the skin material (m 2 / m 2 ) and the surface area per unit area of ​​the substrate (m 2 / m 2 ) is 1:5 or more and less than 1:40 (skin material:base material). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] International Publication No. 2021 / 235446 Summary of the Invention [Problem to be solved by the invention]

[0005] In recent years, there has been a demand for sound-absorbing materials that have a low amount of carbon dioxide emissions from crude oil extraction to product disposal (hereinafter also referred to as "carbon dioxide emissions during manufacturing, etc.") and a high sound absorption rate. In this disclosure, "carbon dioxide emissions during manufacturing, etc." refers to the total amount of carbon dioxide emissions during manufacturing, from crude oil extraction to sound-absorbing material production, and carbon dioxide emissions when the sound-absorbing material is disposed of.

[0006] Reducing the amount of resin in sound-absorbing materials is effective in reducing carbon dioxide emissions during manufacturing, etc. However, reducing the amount of resin in sound-absorbing materials tends to reduce sound-absorbing performance.

[0007] Reducing the amount of resin in a sound-absorbing material generally tends to reduce the rigidity of the material. When the rigidity of the sound-absorbing material decreases, there is a risk that the material will be crushed by external pressure. When the sound-absorbing material is crushed, its sound-absorbing performance will decrease. Furthermore, even if resin components (e.g., padding) are uniformly distributed during the manufacturing of the sound-absorbing material, there is a risk that the uniform distribution of the resin components may not be maintained afterwards due to their own weight or punching process, resulting in uneven distribution of the resin components. In such cases, it has been found that the sound absorption coefficient tends to decrease as a result.

[0008] In view of the above-described problems, one embodiment of the present disclosure aims to provide a sound-absorbing material that emits less carbon dioxide during production and has a high sound absorption coefficient. [Means for solving the problem]

[0009] Specific means for solving the above problems include the following aspects. <1> A sound-absorbing material comprising a padding and a skin material disposed on the outermost side, The basis weight of the sound absorbing material is 2000 g / m 2 is as follows: The total surface area per unit area of ​​the skin material (m 2 / m 2 ) to the total surface area per unit area of ​​the filling (m 2 / m 2 ) is less than 10; The thickness of the padding is 40 mm or more, The bulk density of the filling is 37 kg / m 3 is less than the filling is a nonwoven fabric containing thermoplastic resin hollow fibers and thermoplastic resin solid fibers having an average fiber diameter different from the average fiber diameter of the thermoplastic resin hollow fibers, The total surface area of ​​the outer diameter of the fibers constituting the batting per unit area of ​​the batting is 160m2 / m 2 Super 270m 2 / m 2 is as follows: The sound-absorbing material, wherein the skin material is a nonwoven fabric containing thermoplastic resin fibers. <2> The thermoplastic resin hollow fibers include thermoplastic resin hollow fibers having an average fiber diameter of 20 μm to 50 μm. <1> The sound-absorbing material described in <3> The content of the thermoplastic resin hollow fibers having an average fiber diameter of 20 μm to 50 μm relative to the total amount of the filling is 25% by mass to 60% by mass. <2> The sound-absorbing material described in <4> The filling further contains thermoplastic resin solid fibers having an average fiber diameter of 10 μm or more and less than 20 μm. <3> The sound-absorbing material described in <5> Each of the thermoplastic resin hollow fibers and the thermoplastic resin solid fibers contains one of a polypropylene-based resin and a polyester-based resin. <3> or <4> The sound-absorbing material described in <6> At least one of the thermoplastic resin hollow fibers and the thermoplastic resin solid fibers contains the polyester-based resin, The polyester resin includes a recycled polyethylene terephthalate. <5> The sound-absorbing material described in <7> the skin material includes a first spunbond nonwoven fabric, a meltblown nonwoven fabric adjacent to the first spunbond nonwoven fabric, a second spunbond nonwoven fabric adjacent to the meltblown nonwoven fabric, and a third spunbond nonwoven fabric adjacent to the second spunbond nonwoven fabric; The third spunbond nonwoven fabric contains thermoplastic resin fibers having an average fiber diameter of 25 μm to 50 μm. <1> ~ <6> 10. A sound-absorbing material according to any one of the preceding items. <8> At least one of the first spunbond nonwoven fabric, the meltblown nonwoven fabric, and the third spunbond nonwoven fabric comprises thermoplastic resin hollow fibers. <7> The sound-absorbing material described in <9> The fabric further includes an adhesive portion for joining the padding and the cover material. <1> ~ <8> 10. A sound-absorbing material according to any one of the preceding items. <10> The carbon dioxide emissions of the skin material and the padding are 6.0 kg / m 2 is as follows: The carbon dioxide emissions are calculated in accordance with the calculation method for the 3R basic unit reported by the Recycling Society Promotion Office, Planning Division, Waste Management and Recycling Department, Ministry of the Environment, <1> ~ <9> 10. A sound-absorbing material according to any one of the preceding items. <11> The aforementioned <1> ~ <10> 1. A sound-absorbing panel comprising: a sound-absorbing material according to any one of claims 1 to 9; and a frame that houses the sound-absorbing material. [Effects of the Invention]

[0010] According to one embodiment of the present disclosure, a sound-absorbing material and a sound-absorbing panel are provided that emit little carbon dioxide during manufacturing and have a high sound absorption coefficient. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 1 shows a cross-sectional view of an example of a sound-absorbing material of the present disclosure. [Figure 2] FIG. 2 shows a cross-sectional view of another example of a sound-absorbing material of the present disclosure. [Figure 3] FIG. 3 shows a cross-sectional view of an example of an acoustic panel according to the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0012]

[0023] The following describes embodiments of the present disclosure. These descriptions and examples are intended to illustrate the embodiments and are not intended to limit the scope of the embodiments. In the numerical ranges described in stages in this disclosure, the upper or lower limit value described in one numerical range may be replaced with the upper or lower limit value of another numerical range described in stages. In the numerical ranges described in this disclosure, the upper or lower limit value of the numerical range may be replaced with the value shown in the examples. In the present disclosure, each component may contain multiple corresponding substances. When referring to the amount of each component in a composition in the present disclosure, if multiple substances corresponding to each component are present in the composition, the total amount of the multiple substances present in the composition is meant unless otherwise specified. In this disclosure, the term "process" refers not only to an independent process, but also to a process that cannot be clearly distinguished from other processes, as long as the purpose of that process is achieved. In this disclosure, a numerical range indicated using "to" indicates a range that includes the numerical values ​​before and after "to" as the minimum and maximum values, respectively. In this disclosure, the content of each component in a composition means the total amount of the multiple substances present in the composition, unless otherwise specified, when multiple substances corresponding to each component are present in the composition.

[0013] (1) Sound-absorbing material The sound-absorbing material of the present disclosure (hereinafter also simply referred to as "sound-absorbing material") is a sound-absorbing material comprising a padding and a skin material arranged on the outermost side. The basis weight of the sound-absorbing material is 2000 g / m 2 The total surface area per unit area of ​​the skin material (m 2 / m 2 ) to the total surface area per unit area of ​​the filling (m 2 / m 2 The ratio of the filling material to the surface material (hereinafter also referred to as the "ratio (filling material / surface material)") is less than 10. The thickness of the filling material is 40 mm or more. The bulk density of the filling material is 37 kg / m 3 The filling is a nonwoven fabric containing thermoplastic resin hollow fibers (hereinafter simply referred to as "hollow fibers") and thermoplastic resin solid fibers (hereinafter simply referred to as "solid fibers") having an average fiber diameter different from that of the thermoplastic resin hollow fibers. The sum of the surface areas of the outer diameters of the fibers constituting the filling per unit area of ​​the filling (hereinafter simply referred to as "total surface area") is less than 160 m 2 / m 2 Super 270m 2 / m 2 The skin material is a nonwoven fabric containing thermoplastic resin fibers.

[0014] In this disclosure, "sound-absorbing material" refers to a material used for the purpose of absorbing sound. "Thermoplastic resin hollow fiber" refers to a hollow fiber containing a thermoplastic resin. "Hollow fiber" refers to a straw-shaped fiber. Specifically, a hollow fiber has a hollow portion extending inside along the fiber axis direction. "Thermoplastic resin solid fiber" refers to a solid fiber containing a thermoplastic resin. "Solid fiber" refers to a fiber that is not a hollow fiber. Specifically, a solid fiber does not have a hollow portion extending inside along the fiber axis direction.

[0015] The "total surface area of ​​the outer diameter of the fibers constituting the filling per unit area of ​​the filling" is calculated as follows. For each fiber constituting the filling, the surface area of ​​the outer diameter of the fibers constituting the filling per unit area of ​​the filling is calculated according to the following formula (1), and the total of all fibers constituting the filling is taken as the "total surface area." "Fibers constituting the filling" includes thermoplastic resin hollow fibers and thermoplastic resin solid fibers. For hollow fibers, the outer diameter of the fiber cross section (n=10) is measured using an electron microscope and the average value is calculated. For denier, the denier value listed in the fiber product specifications is used. Formula (1): The surface area of ​​the outer diameter of the fiber that makes up the filling per unit area of ​​the filling (m 2 / m 2 ) = fiber diameter (outer diameter μm) / 10 6 ×3.14×9000(m) / Denier(g)×Count(g / m 2 )×Content (mass%) / 100

[0016] The sound-absorbing material of the present disclosure has the above-described configuration, and therefore emits less carbon dioxide during production, etc., and has a high sound absorption coefficient. Therefore, the sound-absorbing material of the present disclosure has excellent sound-absorbing performance. This effect is presumably due to, but not limited to, the following reasons. Weight is 2000g / m 2 In the following sound-absorbing materials, the fibers used in the padding are a combination of multiple fibers with different average fiber diameters, the multiple fibers include thermoplastic resin hollow fibers, and the total surface area of ​​the outer diameter of the padding fibers per unit area of ​​the padding is 160m 2 / m 2 Super 270m2 / m 2 The following features are important for achieving the effects of the present disclosure. When the above configuration is provided, sound waves that reach the padding are appropriately diffused within the padding, and are attenuated by colliding with multiple fibers (surfaces) of the padding. This allows sound absorption performance to be maintained at a good level. Furthermore, by configuring the padding as described above, it is possible to impart appropriate cushioning properties to the padding, thereby preventing the sound-absorbing material from colliding. As a result, it is estimated that the sound-absorbing material of the present disclosure will emit less carbon dioxide during manufacturing, etc., and will be able to increase the sound absorption coefficient of the sound-absorbing material.

[0017] The shape of the sound-absorbing material is not particularly limited and may be appropriately selected depending on the object of sound absorption. The sound-absorbing material may be in the form of a sheet or a pouch.

[0018] When the sound-absorbing material is in the form of a sheet, the layer structure of the sound-absorbing material is not particularly limited as long as it includes a padding and a skin material, and may be a layer structure of three or more layers. For example, as shown in Fig. 1, the sound-absorbing material 1 has a padding 2 and a skin material 3. The padding 2 is layered on one main surface of the skin material 3.

[0019] The sheet-like sound-absorbing material can be used by cutting (for example, cutting with a cutter) into any shape depending on the application. Hereinafter, this cutting process will also be referred to as "punching." Generally, sound-absorbing materials with low basis weight are easily crushed. Therefore, the thickness of the sound-absorbing material after punching may be thinner than the thickness of the sound-absorbing material before punching. As a result, the sound-absorbing performance decreases. Surprisingly, it has been found that the sound-absorbing material of the present disclosure maintains the thickness of the sound-absorbing material after punching, even if the sound-absorbing material has a low basis weight. Here, the difference between the thickness of the sound-absorbing material after punching and the thickness of the sound-absorbing material before punching is preferably 0 mm or more. Depending on the configuration of the sound-absorbing material and the conditions of the punching, the difference may be 0.5 mm or more, 1.0 mm or more, 2.0 mm or more, or 3.0 mm or more. If the difference is 0 mm or more and exceeds 10% of the thickness of the sound-absorbing material before punching, it becomes difficult for the sound-absorbing material to fit into the sound-absorbing panel, so it is preferable that the upper limit of the difference be 10% or less of the thickness of the sound-absorbing material before punching. Although it is unclear why punching does not reduce the thickness of the sound-absorbing material, it is thought that this is due to the cushioning properties of the padding in the sound-absorbing material of the present disclosure. It is presumed that when the pressure applied during punching is released, the cushioning properties of the padding, which correspond to the fiber composition of the padding, restore the thickness of the padding. When the hollow fiber content of the batting of the present disclosure is high, or when the hollow fibers blended into the batting have a large average fiber diameter (i.e., large hollow fibers), the thickness of the sound-absorbing material tends to be easily restored after punching. Because the rigidity of hollow fibers (large hollow fibers) is higher than that of solid fibers, it is presumed that the rigidity of batting blended with hollow fibers will be higher than that of batting not blended with hollow fibers. Preferred aspects of sound-absorbing materials vary depending on the application. For applications requiring cushioning properties, an aspect with a high hollow fiber content is preferred.

[0020] When the sound-absorbing material is in the form of a pouch, it may include a filling and a skin material that contains the filling. As shown in Fig. 2, the sound-absorbing material 1 has a filling 2, one skin material 3, and a sealing portion 4. The filling 2 is contained in the skin material 3. The filling 2 is sandwiched between the skin material 3 that is folded in half. The three peripheral edges of the folded skin material 3 are sealed by the sealing portion 4. The sealing portion 4 may be formed by thermocompression bonding or ultrasonic sealing.

[0021] The basis weight of the sound-absorbing material of the present disclosure is set to 2000 g / m from the viewpoint of reducing carbon dioxide emissions. 2 From the viewpoint of further improving the total sound absorption coefficient (mainly from the viewpoint of improving the sound absorption coefficient in the range of 100 Hz to 2000 Hz) and from the viewpoint of preventing a decrease in workability due to an increase in the mass of the sound absorbing material, the basis weight of the sound absorbing material is preferably 1000 g / m 2 Super 2000g / m 2 or less, more preferably 1100 g / m 2 ~2000g / m 2 , and more preferably 1100 g / m 2 ~1800g / m 2 From the viewpoint of ensuring the strength of the structure that supports the sound-absorbing material, the basis weight of the sound-absorbing material is 1200 g / m 2 ~1800g / m 2 The method for measuring the basis weight of the sound absorbing material is the same as that described in the examples.

[0022] The thickness of the sound-absorbing material is preferably more than 40 mm and not more than 100 mm, more preferably more than 40 mm and not more than 70 mm, from the viewpoint of further improving the sound absorption coefficient in the low frequency range (particularly 100 Hz to 2000 Hz) and from the viewpoint of ensuring efficient space when installing it in a structure, etc.

[0023] The ratio (filling / skin material) is less than 10. The ratio (filling / skin material) is preferably 5.5 or more and less than 10, more preferably 6.0 to 9.0. By appropriately increasing the rigidity of the skin material in the sound-absorbing material, the compression resistance of the sound-absorbing material can be improved. In particular, a ratio (filling / skin material) of less than 10, combined with the specific filling configuration of the present disclosure, exhibits the effect of excellent compression resistance. Although the mechanism is unknown, it is thought that the skin material absorbs part of the compressive load applied to the sound-absorbing material during punching, thereby reducing the compressive load applied to the filling. Furthermore, since the filling contains solid fibers and hollow fibers, it acts as a cushion during punching, absorbing the load applied to the sound-absorbing material and restoring the thickness of the sound-absorbing material. As a result, the sound-absorbing material of the present disclosure is less likely to collapse and is more likely to gain thickness, which is presumed to result in excellent sound-absorbing performance. The methods for measuring the total surface area per unit area of ​​the filling and the total surface area per unit area of ​​the skin material were the same as those described in the examples.

[0024] The carbon dioxide emissions from the skin material and padding are not particularly limited, but are generally 6.0 kg / m 2 It is preferable that the sound-absorbing material has a density of 1000 or less. This makes it possible to reduce the environmental load of the sound-absorbing material. "Carbon dioxide emissions" refers to the total amount of carbon dioxide emitted during the manufacturing process from crude oil extraction to the production of sound-absorbing material, plus the amount of carbon dioxide emitted when the sound-absorbing material is disposed of. Carbon dioxide emissions are calculated in accordance with the calculation method for the 3R basic unit reported by the Recycling Society Promotion Office, Planning Division, Waste Management and Recycling Department, Ministry of the Environment. The method for measuring carbon dioxide emissions is the same as that described in the Examples. The carbon dioxide emissions of the skin material and padding are preferably 3.0 kg / m from the viewpoint of achieving both reduced carbon dioxide emissions and sound absorption. 2 ~6.0kg / m 2 , more preferably 4.0 kg / m 2 ~6.0kg / m 2 is.

[0025] (1.1) Padding The sound absorbing material includes a batting, which is a nonwoven fabric including hollow fibers and solid fibers, the solid fibers having an average fiber diameter different from the average fiber diameter of the hollow fibers.

[0026] The type of nonwoven fabric for batting is not particularly limited, and examples of nonwoven fabric for batting include spunbond nonwoven fabric, meltblown nonwoven fabric, wetlaid nonwoven fabric, spunlace nonwoven fabric, drylaid nonwoven fabric, dry pulp nonwoven fabric, carded nonwoven fabric, airlaid nonwoven fabric, waterjet nonwoven fabric, flash-spun nonwoven fabric, open-fiber nonwoven fabric, and needle-punched nonwoven fabric.

[0027] The thickness of the padding is 40 mm or more. The thickness of the padding can be adjusted appropriately depending on the size of the sound-absorbing panel to be used. From the viewpoint of further improving the total sound absorption coefficient (particularly 100 Hz to 2000 Hz), the thickness of the padding is preferably 40 mm to 100 mm, more preferably 40 mm to 70 mm. The method for measuring the thickness of the padding is the same as that described in the examples.

[0028] The bulk density of the filling is 37 kg / m 3 The bulk density of the padding is preferably less than 20 kg / m from the viewpoint of preventing uneven distribution within the panel. 3 Super 37kg / m 3 less than 24 kg / m 3 More than 37kg / m 3 less than 24 kg / m 3 ~35kg / m 3 By having the bulk density of the filling fall within the above range, sound waves transmitted to the filling can be diffused appropriately. Furthermore, by improving the cushioning properties of the filling, it is possible to suppress the crushing of the sound-absorbing material during punching. The method for measuring the bulk density of the filling is the same as that described in the Examples.

[0029] The total surface area of ​​the padding is 160m 2 / m 2 Super 270m 2 / m 2 The total surface area of ​​the padding is preferably 190 m² from the viewpoint of sound absorption performance and cushioning. 2 / m 2 ~270m 2 / m 2 is.

[0030] The basis weight of the padding of the present disclosure is set to 2000 g / m or less from the viewpoint of reducing carbon dioxide emissions. 2 From the viewpoint of further improving the total sound absorption coefficient (mainly 100 Hz to 2000 Hz) and preventing a decrease in workability due to an increase in the mass of the sound absorbing material, the weight of the filling is preferably 1000 g / m 2 Super 2000g / m 2 or less, more preferably 1100 g / m 2 ~2000g / m 2 , and more preferably 1200 g / m 2 ~2000g / m 2 Furthermore, in order to ensure the strength of the padding structure that supports the sound absorbing material, the weight of the padding is 1200 g / m 2 ~1800g / m 2 The method for measuring the basis weight of the filling is the same as that described in the examples.

[0031] The layer structure of the padding is not particularly limited, and may be a single layer, two layers, three layers, or four or more layers.

[0032] The batting (i.e., nonwoven fabric) includes hollow fibers and solid fibers, and may further include known fibers different from hollow fibers and solid fibers. The batting may consist of hollow fibers and solid fibers.

[0033] The amount of padding relative to the total amount of sound-absorbing material is not particularly limited, but from the viewpoint of ensuring sound-absorbing performance by ensuring the thickness of the padding, it is preferably 80 to 96 parts by mass, and more preferably 84 to 94 parts by mass.

[0034] (1.1.1) Thermoplastic hollow fibers The filling contains a plurality of hollow fibers. The hollow fibers contained in the filling may be of one type or two or more types.

[0035] The hollow ratio of the hollow fiber is not particularly limited. From the viewpoints of lightness and tensile strength, the hollow ratio is preferably 5% to 30%, more preferably 10% to 30%, and even more preferably 14% to 30%. The method for measuring the hollow ratio of the hollow fiber is the same as the method described in the Examples.

[0036] The fineness of the hollow fibers is not particularly limited, and may be 0.6 denier to 30 denier, or 2 denier to 15 denier.

[0037] The hollow fibers may be short fibers or long fibers. The cross-sectional shape of the hollow fibers is not particularly limited, and may be approximately circular, elliptical, irregular, or the like.

[0038] When the hollow fibers are short fibers, the average fiber length of the hollow fibers is not particularly limited and may be 10 mm to 100 mm. The average fiber length of hollow fibers is calculated by randomly selecting 50 fibers from a scanning electron microscope image and averaging the results.

[0039] The average fiber diameter of the hollow fibers is not particularly limited, and may be 10 μm to 70 μm, or 20 μm to 50 μm. The average fiber diameter of hollow fibers is determined as follows: an electron microscope photograph (magnification 1000x) of the filling is taken, and the diameters of the hollow fibers that can be measured from the obtained photograph are measured. The photographing and measurement are repeated until the total number of measured hollow fibers exceeds 100, and the arithmetic mean value of the obtained diameters of the hollow fibers is defined as the "average fiber diameter."

[0040] From the viewpoint of providing cushioning properties to the padding, the padding preferably contains thermoplastic resin hollow fibers (hereinafter also referred to as "thick hollow fibers") having an average fiber diameter of 20 μm to 50 μm. The hollow fibers of the padding may consist solely of thick hollow fibers. Depending on the conditions of the punching process, if the padding has cushioning properties, the thickness of the sound-absorbing material can be maintained after the punching process.

[0041] The hollow fiber contains a thermoplastic resin, but the thermoplastic resin is not particularly limited. Examples of thermoplastic resins include: (i) biodegradable resins such as polylactic acid, polyhydroxyalkanoate, polybutylene succinate, cellulose acetate, polyvinyl alcohol, polyglycolic acid, polybutylene succinate-co-adipate, polybutylene adipate terephthalate, or polyethylene terephthalate succinate; (ii) polyolefin resins such as low-density polyethylene, medium-density polyethylene, high-density polyethylene, ultra-high-density polyethylene, polypropylene, polymethylpentene, or copolymers thereof; (iii) chlorine-containing resins such as polyvinyl chloride (PVC) or polyvinylidene chloride (PVDC); (iv) fluorine-containing resins such as tetrafluoroethylene resins, ethylene-tetrafluoroethylene copolymer resins, perfluoroethylenepropene copolymer resins, polychlorotrifluoroethylene resins, and tetrafluoroethylene-perfluoroalkoxyethylene copolymer resins; (v) Addition-type thermoplastic resins other than the addition-type thermoplastic resins shown in (i) to (iv), such as ethylene vinyl acetate resin, polymethyl methacrylate (PMMA) resin, polystyrene-based resin, ABS resin (i.e., acrylonitrile, butadiene, styrene copolymer synthetic resin), or acrylonitrile styrene (AS) resin, (vi) Polyamide resins such as nylon 6, nylon 66, nylon 12, nylon 11, metaxylylene adipamide (MXD6), hexamethylene terephthalamide (6T), or copolymers thereof; (vii) Polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polyethylene-2,6-naphthalate (PEN), polybutylene naphthalate (PBN), polyethylene isophthalate (PEI), polybutylene isophthalate (PBI), polyhexamethylene terephthalate (PHT), polyhexamethylene isophthalate (PHI), polyhexamethylene naphthalate (PHN), polymethylene terephthalate (PMT), polypropylene terephthalate (PPT), poly polyesters (excluding biodegradable polyesters) copolymerized with ethylene-p-oxybenzoate (PEOB), poly-1,4-cyclohexylenedimethylene terephthalate (PCT), and copolymerized components such as diol components (e.g., diethylene glycol, neopentyl glycol, or polyalkylene glycol) or dicarboxylic acid components (e.g., adipic acid, sebacic acid, phthalic acid, isophthalic acid, or 2,6-naphthalenedicarboxylic acid), and polyester-based resins such as liquid crystal polyesters; (viii) Condensation thermoplastic resins other than the condensation thermoplastic resins shown in (vi) and (vii), such as polyamide-imide resin, thermoplastic polyimide, thermoplastic polyurethane, polycarbonate resin, polyacetal (POM) resin, polyetherimide (PEI) resin, polyphenylene ether (PPE) resin, polyether ether ketone (PEEK) resin, or polyphenylene sulfide (PPS) resin, are included.

[0042] The thermoplastic resin may be virgin, may contain recycled material, or may be recycled.

[0043] The thermoplastic resin of the hollow fibers may include a polyester-based resin (e.g., polyethylene terephthalate) or a polypropylene-based resin. The hollow fibers may include hollow fibers containing a polyester-based resin and hollow fibers containing a polypropylene-based resin.

[0044] The hollow fiber may contain additives, such as heat stabilizers, ultraviolet absorbers, weather stabilizers, flame retardants, water repellents, oils, antistatic agents, colorants, and inorganic substances, as long as the additives do not impair the effects of the present disclosure.

[0045] The content of hollow fibers relative to the total amount of filling is not particularly limited, and may be 25% by mass to 60% by mass, or 30% by mass to 50% by mass. When the hollow fibers contain thick hollow fibers, the content of the thick hollow fibers relative to the total amount of the filling is preferably 25% by mass to 60% by mass, more preferably 30% by mass to 50% by mass, from the viewpoint of providing cushioning properties to the filling.

[0046] The content of hollow fibers relative to the total amount of hollow fibers and solid fibers is not particularly limited, and may be 25% by mass to 60% by mass, or 30% by mass to 50% by mass. When the hollow fibers contain thick hollow fibers, the content of the thick hollow fibers relative to the total amount of hollow fibers and solid fibers is not particularly limited, and may be 25% to 60% by mass, preferably 30% to 50% by mass. Blending an appropriate amount of thick hollow fibers with appropriate rigidity can contribute to improving the cushioning properties of the padding. As a result, the thickness of the sound-absorbing material can be maintained after punching.

[0047] (1.1.2) Thermoplastic resin solid fiber The filling contains a plurality of solid fibers. The solid fibers contained in the filling may be one type or two or more types. The solid fibers may be adhesive fibers. From the viewpoint of providing cushioning properties to the filling, it is preferable to use two or more types of solid fibers with different fiber diameters.

[0048] The fineness of the solid fiber is not particularly limited, and may be 1 denier to 48 denier, or 1 denier to 25 denier.

[0049] The solid fibers may be short fibers or long fibers. The cross-sectional shape of the solid fibers is not particularly limited, and may be substantially circular, elliptical, irregular, or the like. The solid fiber may be a bicomponent fiber or a monocomponent fiber, and the bicomponent fiber is preferably made of two or more thermoplastic resins. Examples of composite fibers include sheath-core, side-by-side, islands-in-sea, and side-by-side types. Sheath-core composite fibers have only to have a core and a sheath, and may be either a concentric sheath-core type or an eccentric sheath-core type. Eccentric sheath-core composite fibers may have the core exposed on the surface, or may not have the core exposed on the surface. Islands-in-sea composite fibers have a sea phase and multiple island phases.

[0050] When the solid fibers are short fibers, the average fiber length of the solid fibers is not particularly limited and may be 10 mm to 100 mm. The method for measuring the average fiber length of solid fibers is the same as the method for measuring the average fiber length of hollow fibers.

[0051] The average fiber diameter of the solid fibers is not particularly limited and may be 10 μm to 70 μm. From the viewpoint of providing cushioning properties to the filling, one of the solid fibers with different fiber diameters may preferably be a thermoplastic resin solid fiber having an average fiber diameter of 10 μm to 20 μm (hereinafter also referred to as a "fine solid fiber"). When the filling contains fibers thinner than the thick hollow fibers, sound waves tend to be more easily diffused and sound absorption performance tends to be improved. The other average fiber diameter may preferably be a thermoplastic resin solid fiber having an average fiber diameter of 20 μm to 50 μm (hereinafter also referred to as a "thick solid fiber"). When the filling contains thick solid fibers, uneven distribution of the filling, thickness changes due to punching, and compression resistance characteristics can be suppressed. The method for measuring the average fiber diameter of solid fibers is the same as the method for measuring the average fiber diameter of hollow fibers.

[0052] The solid fibers of the batting may consist of only fine solid fibers or only thick solid fibers. From the viewpoint of improving sound absorption performance, the solid fibers of the batting preferably include both fine solid fibers and thick solid fibers. From the viewpoint of achieving both sound absorption performance and compression resistance, the batting preferably includes hollow fibers and solid fibers, and more preferably includes thick hollow fibers, thin solid fibers, and thick solid fibers.

[0053] The solid fiber contains a thermoplastic resin. The thermoplastic resin is not particularly limited. Examples of the thermoplastic resin for the solid fiber include the same thermoplastic resins as those exemplified for the hollow fiber.

[0054] The thermoplastic resin of the solid fibers may include a polyester-based resin or a polypropylene-based resin. The solid fibers may include solid fibers containing a polyester-based resin and solid fibers containing a polypropylene-based resin.

[0055] The solid fiber may include a solid fiber having adhesive properties (hereinafter also referred to as "adhesive fiber"), and may be an adhesive fiber. The adhesive fiber may be a core-sheath type. The sheath contains a binder component. Examples of the binder component include terephthalic acid or its ester-forming derivative, isophthalic acid or its ester-forming derivative, lower alcohol, and a copolymer polyester composed of polyalkylene glycol or its monoether. The core contains the above-mentioned thermoplastic resin, and may contain polyethylene terephthalate.

[0056] The solid fiber may contain additives, such as heat stabilizers, ultraviolet absorbers, weather stabilizers, flame retardants, water repellents, oils, antistatic agents, colorants, or inorganic substances, as long as the additives do not impair the effects of the present disclosure.

[0057] The content of solid fibers relative to the total amount of filling is not particularly limited, and may be 40% to 75% by mass, or 50% to 70% by mass. When the solid fibers include fine solid fibers, the content of the fine solid fibers relative to the total amount of the filling is not particularly limited, but is preferably 20% to 40% by mass, more preferably 25% to 35% by mass.

[0058] The content of solid fibers relative to the total amount of hollow fibers and solid fibers is not particularly limited, and may be 40% by mass to 75% by mass, or 50% by mass to 70% by mass. When the solid fibers include fine solid fibers, the content of the fine solid fibers relative to the total amount of hollow fibers and solid fibers is not particularly limited and may be 20% to 40% by mass, or 25% to 35% by mass. In particular, when the solid fibers include fine solid fibers, the fine solid fibers preferably include adhesive fibers, and the fine solid fibers may be adhesive fibers. When the fine solid fibers are adhesive fibers and the content of the fine solid fibers relative to the total amount of hollow fibers and solid fibers is 25% to 35% by mass, it is possible to provide the filling with appropriate cushioning properties while ensuring appropriate inter-fiber adhesive strength. When the solid fibers include thick solid fibers, the content of the thick solid fibers relative to the total amount of the filling is not particularly limited, but is preferably 10% by mass to 50% by mass, more preferably 15% by mass to 40% by mass, and even more preferably 15% by mass to 35% by mass. From the viewpoint of cushioning properties of the filling, the solid fibers may include various solid fibers in addition to thin solid fibers and thick solid fibers.

[0059] (1.1.3) Preferred embodiment In the present disclosure, it is preferable that condition (2) is met. "Condition (2)" means: This indicates that the thermoplastic resin hollow fibers include thermoplastic resin hollow fibers having an average fiber diameter of 20 μm to 50 μm (that is, thick hollow fibers). When condition (2) is satisfied, the sound absorbing performance and compression resistance of the sound absorbing material are improved.

[0060] In the present disclosure, it is preferable that conditions (2) and (3) are satisfied. "Condition (3)" means: This indicates that the content of the thermoplastic resin hollow fibers having an average fiber diameter of 20 μm to 50 μm relative to the total amount of the filling is 25% by mass to 60% by mass. When the conditions (2) and (3) are satisfied, the compression resistance of the sound absorbing material is improved.

[0061] In the present disclosure, it is preferable that conditions (2) to (4) be satisfied. "Condition (4)" means: It indicates that the batting further contains thermoplastic resin solid fibers having an average fiber diameter of 10 μm or more and less than 20 μm (that is, fine solid fibers). By satisfying conditions (2) to (4), the sound absorbing performance of the sound absorbing material and the cushioning properties of the padding (compression resistance of the sound absorbing material) are improved.

[0062] In the present disclosure, it is preferable that conditions (2) to (5) be satisfied. "Condition (5)" indicates that the thermoplastic resin hollow fiber and the thermoplastic resin solid fiber each contain one of a polypropylene-based resin and a polyester-based resin. By satisfying the conditions (2) to (5), the sound absorbing performance of the sound absorbing material is further improved.

[0063] The padding preferably contains fine solid fibers containing a polypropylene resin (hereinafter also referred to as "polypropylene resin fibers") and thick hollow fibers containing a polyester resin (hereinafter also referred to as "polyester resin fibers"). In this case, the mass ratio of the polyester resin fibers to the polypropylene resin fibers (polyester resin fibers / polypropylene resin fibers) is preferably 99 / 1 to 5 / 95, more preferably 95 / 5 to 10 / 90, and even more preferably 80 / 20 to 20 / 80, from the viewpoint of further improving the sound absorption coefficient.

[0064] In the present disclosure, it is preferable that conditions (2) to (6) be satisfied. "Condition (6)" indicates that at least one of the thermoplastic resin hollow fiber and the thermoplastic resin solid fiber contains the polyester-based resin, and the polyester-based resin contains a recycled polyethylene terephthalate. By satisfying the conditions (2) to (6), the environmental impact of the sound-absorbing material is further reduced. In particular, the recycled polyethylene terephthalate preferably includes “polyethylene terephthalate discharged or recovered from railway-related businesses.” When the polyethylene terephthalate discharged or recovered from railway-related businesses contains a relatively high amount of impurities, it may tend to have improved low-temperature impact resistance.

[0065] The batting is preferably a batting (hereinafter also referred to as "first batting") consisting of thick hollow fibers, thin solid fibers as adhesive fibers, thick solid fibers, and other solid fibers. "Other solid fibers" refers to solid thermoplastic resin fibers different from the thin solid fibers and thick solid fibers. Specifically, "other solid fibers" refers to solid thermoplastic resin fibers having an average fiber diameter of less than 10 μm or more than 50 μm.

[0066] When the filling is the first filling, the content of each fiber constituting the filling is preferably as follows. The content of the thick hollow fibers relative to the total amount of the first filling may be 25% by mass to 60% by mass, or may be 30% by mass to 50% by mass. The content of the fine solid fibers relative to the total amount of the first filling may be 20% by mass to 40% by mass, or may be 25% by mass to 35% by mass. The content of the thick solid fiber relative to the total amount of the first filling may be 10% by mass to 50% by mass, 15% by mass to 40% by mass, or 15% by mass to 35% by mass. The content of the other solid fibers relative to the total amount of the first filling may be the remainder.

[0067] (1.2) Skin material The sound-absorbing material includes a skin material. The skin material is a nonwoven fabric containing thermoplastic resin fibers. The skin material may be a nonwoven fabric made of thermoplastic resin fibers.

[0068] The type of nonwoven fabric for the skin material is not particularly limited, and examples of the nonwoven fabric for the skin material include the same nonwoven fabrics as those exemplified as the nonwoven fabric for the padding.

[0069] The thickness of the skin material is not particularly limited. The thickness of the skin material is preferably 0.1 mm to 1.5 mm, more preferably 0.3 to 1.0 mm. When the thickness of the skin material is 0.1 mm to 1.5 mm, it is possible to further improve the water pressure resistance and further prevent contact between the filling and water, maintain strength (e.g., shot blast resistance, etc.), prevent the filling from being too thick and preventing sound waves from being difficult to transmit to the filling, and prevent the filling from being too thick and reducing the workability of ultrasonic sealing, etc. The method for measuring the thickness of the skin material is the same as the method for measuring the thickness of the filling.

[0070] Sum of surface areas per unit area of ​​skin material (m 2 / m 2 ) is not particularly limited, but from the viewpoint of improving sound absorption performance, it is preferably 20 m 2 / m 2 ~40m 2 / m 2 , preferably 24m 2 / m 2 ~36m 2 / m 2 is.

[0071] The average fiber diameter of the thermoplastic resin fibers located near the surface of the skin material (hereinafter also referred to as "surface fiber diameter") is preferably 10 μm to 100 μm from the viewpoint of ensuring the strength of the structure that supports the sound-absorbing material. The surface fiber diameter is more preferably 20 μm to 100 μm, and even more preferably 25 μm to 50 μm, from the viewpoints of further improving shot blast resistance, controlling air permeability within an appropriate range, and suppressing crushing of the sound-absorbing material during punching.

[0072] The water pressure resistance of the skin material is preferably 200 mmH2O to 2000 mmH2O, more preferably 200 mmH2O to 500 mmH2O, from the viewpoint of further preventing contact between the filling and water. The water pressure resistance of the skin material can be further increased by at least one method selected from the group consisting of reducing the average fiber diameter of the fibers constituting the skin material, increasing the density of the skin material, using fibers made of a thermoplastic resin (for example, a polypropylene-based resin or a polyester-based resin), and increasing the basis weight of the skin material.

[0073] The breathability of the skin material is preferably 5 cm from the viewpoint of further improving the water pressure resistance and further preventing contact between the padding and water, and from the viewpoint of adequately transmitting sound waves to the padding side to maintain a good sound absorption coefficient. 3 / cm 2 / sec~200cm 3 / cm 2 / sec, more preferably 7cm 3 / cm 2 / sec~150cm 3 / cm 2 / seconds.

[0074] The layer structure of the skin material is not particularly limited and may be a single layer, two layers, three layers, or four or more layers. The skin material may have a laminated structure (SMS structure) in which a first spunbond nonwoven fabric, a meltblown nonwoven fabric, and a second spunbond nonwoven fabric are laminated in this order. The skin material may have a laminated structure (SMSS structure) in which a first spunbond nonwoven fabric, a meltblown nonwoven fabric, a second spunbond nonwoven fabric, and a third spunbond nonwoven fabric are laminated in this order.

[0075] When the skin material has an SMS structure, the average fiber diameter of the thermoplastic resin fibers constituting each layer is preferably within the following ranges from the viewpoint of improving sound absorption performance. The average fiber diameter of the first spunbond nonwoven fabric is preferably 10 μm to 20 μm, more preferably 12 μm to 16 μm. The average fiber diameter of the meltblown nonwoven fabric is preferably 1 μm to 6 μm, more preferably 2 μm to 5 μm. The average fiber diameter of the second spunbond nonwoven fabric is preferably 10 μm to 20 μm, more preferably 12 μm to 16 μm.

[0076] When the skin material has an SMSS structure, the average fiber diameter of the thermoplastic resin fibers constituting each layer is preferably within the following ranges from the viewpoints of improving sound absorption performance and compression resistance. The average fiber diameter of the first spunbond nonwoven fabric is preferably 10 μm to 20 μm, more preferably 12 μm to 16 μm. The average fiber diameter of the meltblown nonwoven fabric is preferably 1 μm to 6 μm, more preferably 2 μm to 5 μm. The average fiber diameter of the second spunbond nonwoven fabric is preferably 10 μm to 20 μm, more preferably 12 μm to 16 μm. The average fiber diameter of the third spunbond nonwoven fabric is preferably 25 μm to 50 μm, more preferably 30 μm to 40 μm.

[0077] The skin material (i.e., nonwoven fabric) contains thermoplastic resin fibers and may further contain known fibers different from the thermoplastic resin fibers. The skin material may be made of thermoplastic resin fibers.

[0078] The content of the skin material relative to the total amount of the sound-absorbing material is not particularly limited and can be set appropriately depending on the frequency of the noise to be removed. It is preferably 4 to 20 parts by mass, and from the viewpoint of improving sound-absorbing performance and compression resistance, more preferably 6 to 16 parts by mass.

[0079] (1.2.1) Thermoplastic resin fibers The skin material contains a plurality of thermoplastic resin fibers, and the thermoplastic resin fibers contained in the skin material may be of one type or two or more types.

[0080] The fineness of the thermoplastic resin fibers is not particularly limited, and may be 0.6 denier to 64 denier, or 4 denier to 16 denier.

[0081] The thermoplastic resin fibers may be long fibers or short fibers. The cross-sectional shape of the thermoplastic resin fibers is not particularly limited, and examples thereof include a substantially circular shape, an elliptical shape, and an irregular shape. The thermoplastic resin fiber may be a hollow fiber or a solid fiber. When the thermoplastic resin fiber is a solid fiber, the thermoplastic resin fiber may be a bicomponent fiber or a monocomponent fiber. The bicomponent fiber preferably contains two or more thermoplastic resins as constituent components. Examples of composite fibers include sheath-core, side-by-side, islands-in-sea, and side-by-side types. Sheath-core composite fibers have only to have a core and a sheath, and may be either a concentric sheath-core type or an eccentric sheath-core type. Eccentric sheath-core composite fibers may have the core exposed on the surface, or may not have the core exposed on the surface. Islands-in-sea composite fibers have a sea phase and multiple island phases.

[0082] The solid fiber may contain additives, such as heat stabilizers, ultraviolet absorbers, weather stabilizers, flame retardants, water repellents, oils, antistatic agents, colorants, or inorganic substances, as long as the additives do not impair the effects of the present disclosure.

[0083] The content of the thermoplastic resin fibers relative to the total amount of the skin material is not particularly limited, and may be 50% by mass or more, 80% to 100% by mass, or even 100% by mass.

[0084] (1.2.2) Preferred embodiment In the present disclosure, it is preferable that condition (7) is satisfied. "Condition (7)" means: the skin material includes a first spunbond nonwoven fabric, a meltblown nonwoven fabric adjacent to the first spunbond nonwoven fabric, a second spunbond nonwoven fabric adjacent to the meltblown nonwoven fabric, and a third spunbond nonwoven fabric adjacent to the second spunbond nonwoven fabric; The third spunbond nonwoven fabric contains thermoplastic resin fibers having an average fiber diameter of 25 μm to 50 μm. If the surface of the skin material (the third spunbond nonwoven fabric) is soft, the thickness of the skin material after cutting with a cutter during punching may become uneven. Condition (7) means that relatively thick thermoplastic resin fibers should be placed in the third spunbond nonwoven fabric, which is the outermost surface of the skin material and the surface that the cutter first comes into contact with. When the third spunbond nonwoven fabric contains relatively thick thermoplastic resin fibers, the cutter's teeth make better contact with the third spunbond nonwoven fabric, preventing localized crushing of the filling. This makes it easier to achieve a uniform thickness of the sound-absorbing material after cutting, thereby suppressing uneven distribution of the filling after punching. Condition (7) is particularly useful when the basis weight of the sound-absorbing material is reduced. As a result, the sound-absorbing performance of the sound-absorbing material is improved.

[0085] In the present disclosure, it is preferable that conditions (7) and (8) are satisfied. "Condition (8)" means: At least one of the first spunbond nonwoven, the meltblown nonwoven, and the third spunbond nonwoven comprises thermoplastic hollow fibers. When the conditions (7) and (8) are satisfied, the effect of reducing the environmental load of the sound-absorbing material becomes even more excellent.

[0086] (1.3) Adhesive part The sound-absorbing material may further include an adhesive portion that bonds the padding and the covering material, or may not include an adhesive portion. The sound-absorbing material preferably includes an adhesive portion.

[0087] The adhesive region may be formed on the entire interface between the padding and the skin material, or may be formed on a part of the interface between the padding and the skin material.

[0088] The adhesive forming the adhesive portion is not particularly limited, and any known adhesive may be used. Examples of the adhesive include hot melt adhesives. Examples of the hot melt adhesive include resin adhesives (e.g., polyolefin adhesives, ethylene vinyl acetate adhesives, polyamide adhesives, polyurethane adhesives, etc.) and rubber adhesives (e.g., styrene-butadiene adhesives, styrene-isoprene adhesives, etc.).

[0089] (2) Sound-absorbing panels The sound-absorbing panel of the present disclosure comprises the sound-absorbing material of the present disclosure and a frame that houses the sound-absorbing material.

[0090] The sound-absorbing panel of the present disclosure has the above-described configuration and therefore exhibits the same effects as the sound-absorbing material of the present disclosure.

[0091] Next, an example of a sound-absorbing panel of the present disclosure will be described with reference to Fig. 3. As shown in Fig. 3, the sound-absorbing panel 11 includes a sound-absorbing material 1, a frame 14, a protective panel 15, and a support portion 16.

[0092] The frame 14 houses the sound-absorbing material 1. The frame 14 is a box-shaped body with an open end at the top. The frame 14 has a rectangular shielding plate 12 that forms the bottom, and side walls 13 that rise from the four sides of the shielding plate 12.

[0093] The protective panel 15 is placed at the open end of the frame 14 when the sound-absorbing material 1 is housed in the frame 14.

[0094] The support portion 16 is disposed on the rear surface of the frame 14 and supports the sound-absorbing panel 11 when the sound-absorbing panel 11 is attached to a building or the like.

[0095] The frame 14 may be formed by integrally forming the shielding plate 12, the side wall 13, and the support portion 16, or may be formed by connecting separate members. The material of the frame 14 is not particularly limited as long as it is a material that is durable against weather, moisture, etc., and may be metal or resin. Examples of metal include aluminum and stainless steel.

[0096] The protective panel 15 preferably protects the sound-absorbing material 1 from solid objects (for example, hail, sleet, or pebbles) while facilitating the penetration of sound waves. For this reason, in this embodiment, a punched plate with a large number of through holes 15a arranged on the surface is preferably used as the protective panel 15, but the panel is not limited to a punched plate as long as it protects the sound-absorbing material 1 while facilitating the penetration of sound waves. The total area of ​​the through holes 15a relative to the total area of ​​the surface of the protective panel 15 is not particularly limited, but is, for example, in the range of 20% to 80%.

[0097] The material of the protective panel 15 is not particularly limited as long as it can protect the sound-absorbing material 1 and is durable against the penetration of sound waves, weather, moisture, etc., and may be metal or resin. Examples of metal include aluminum and stainless steel. [Example]

[0098] The present disclosure will be described in more detail below based on examples, but the present disclosure is not limited to the following examples. The materials, amounts used, ratios, processing procedures, etc. shown in the following examples can be changed as appropriate without departing from the spirit of the present disclosure. Unless otherwise specified, "parts" means "parts by mass."

[0099] [1]Measurement method In the examples and comparative examples, various physical properties were measured or calculated as follows.

[0100] [1.1] Metsuke Five 10cm square samples were taken from the sound-absorbing material, excluding the side surfaces. The mass of each sample (surface material and padding) was measured. The mass of the sample was divided by the area of ​​the sample to obtain the basis weight (g / m2 The average of the five measured values ​​of basis weight was calculated as "basis weight (g / m 2 )"

[0101] [1.2] Thickness (mm) For the five samples used to measure the basis weight, the thickness was measured at four points in the center of each side surface by placing a vernier caliper vertically. The average value of the thickness measurements at 20 points was recorded as "thickness (mm)."

[0102] [1.3] Bulk density (kg / m 3 ) The thickness defined in [1.2] above was divided by the basis weight defined in [1.1] above to obtain the bulk density.

[0103] [1.4] Average fiber diameter For the spunbond nonwoven fabric, 10 test pieces were taken from the spunbond nonwoven fabric. The size of the test pieces was 10 mm x 10 mm. Using a microscope (Nikon Corporation, product name: ECLIPSE E400) at a magnification of 50x, the fiber diameter was measured at 20 random locations for each test piece in μm units to the first decimal place. The average of the measured fiber diameter values ​​was taken as the "average fiber diameter of the spunbond nonwoven fabric." For the meltblown nonwoven fabric, 10 test pieces were taken from the meltblown nonwoven fabric. The size of the test pieces was 10 mm x 10 mm. The fiber diameters (μm) of 30 constituent fibers of the taken sample pieces were measured at a magnification of 500x or 1000x using a scanning electron microscope (manufactured by Hitachi, Ltd., model name: SU3500). The average value of the fiber diameters was taken as the "average fiber diameter of the meltblown nonwoven fabric."

[0104] [1.5] Sum of the surface area of ​​the outer diameter of the fiber per unit area For each fiber constituting the skin material and the filling, the surface area of ​​the outer diameter of the fiber per unit area of ​​the skin material and the filling was calculated according to the following formula (2), and the total of all fibers in each was taken as the total surface area. For hollow fibers, the outer diameter of the fiber cross section (n=10) was measured using an electron microscope and the average value was calculated. For denier, the denier value listed in the fiber product specifications was used. Equation (2): Surface area of ​​the outer diameter of the filling fiber per unit area of ​​the filling (m 2 / m 2 ) = fiber diameter (outer diameter μm) / 10 6 ×3.14×9000(m) / Denier(g)×Count(g / m 2 )×Content (mass%) / 100

[0105] [1.6] Sound absorption coefficient The normal incidence sound absorption coefficient was measured using test specimens in accordance with JIS A 1405-2 (transfer function method). An acoustic tube with an inner diameter of 100 mm was used as the large tube. An acoustic tube with an inner diameter of 29 mm was used as the small tube. When the sound-absorbing material was a sheet, the test specimen had a padding and a skin material (SMS structure or SSMS structure) placed on the surface of the padding. When the sound-absorbing material was a bag-like material, the test specimen had a padding and a skin material (SMS structure or SSMS structure) placed on both the front and back of the padding. The padding was round and 100 mm in diameter to match the size of the acoustic tube. When the skin material was an SSMS structure, the skin material was positioned so that the third spunbond nonwoven fabric side was the outermost surface of the test specimen. Note that the sound absorption coefficient for the 1 / 3 octave band center frequencies of 125 Hz to 1000 Hz was measured using a large tube. The sound absorption coefficient for the 1 / 3 octave band center frequency of 1250 Hz to 6300 Hz is the result of measurement using a thin tube. The allowable range for the total sound absorption coefficient is 12.10 or greater. The "total sound absorption coefficient" is calculated by determining the normal incidence sound absorption coefficient (hereinafter simply referred to as "sound absorption coefficient") for each of the following frequencies from the obtained sound absorption coefficient curve for 125 Hz to 6300 Hz: 125 Hz, 160 Hz, 200 Hz, 250 Hz, 315 Hz, 400 Hz, 500 Hz, 630 Hz, 800 Hz, 1000 Hz, 1250 Hz, 1600 Hz, 2000 Hz, 2500 Hz, 3150 Hz, 4000 Hz, 5000 Hz, and 6300 Hz, and then calculating the sum of the sound absorption coefficients.

[0106] [1.7] Carbon dioxide emissions Calculations were made in accordance with the calculation method for 3R basic units reported by the Recycling Society Promotion Office, Planning Division, Waste Management and Recycling Department, Ministry of the Environment (see Non-Patent Document 1 below). The term "recycled fiber" encompasses reused fibers. The calculations were made assuming zero carbon dioxide emissions from the process of recycled fiber production, from crude oil extraction to resin production. Furthermore, to precisely evaluate the carbon dioxide emission reduction rate, the carbon dioxide emissions from resin to sound-absorbing material production were calculated using data from the "Carbon Footprint System Pilot Project CO2 Equivalent Common Basic Unit Database ver. 4.01 (Domestic Data)" for nonwoven fabrics containing polypropylene resin fibers, polyolefin fibers, and polyester fibers, respectively, under public reference numbers JP212022 and JP212024. Furthermore, carbon dioxide emissions that may occur during the sound-absorbing material production process were not taken into account and assumed to be zero. A value of 1.49 kg was used to estimate the amount of carbon dioxide emitted from crude oil extraction to resin production per 1 kg of nonwoven fabric and polyolefin fiber containing polypropylene resin fiber. A value of 1.59 kg was used to estimate the amount of carbon dioxide emitted from crude oil extraction to resin production per 1 kg of polyester fiber. Sound-absorbing material was disposed of by incineration, and a value of 3.14 kg was used to estimate the amount of carbon dioxide emitted during incineration per 1 kg of nonwoven fabric and polyolefin fiber containing polypropylene resin fiber. A value of 2.29 kg was used to estimate the amount of carbon dioxide emitted during incineration per 1 kg of polyester fiber. GHG (Greenhouse Gas) emissions were calculated as carbon dioxide emissions. "Calculated in accordance with the calculation method for the 3R basic unit reported by the Recycling Society Promotion Office, Planning Division, Waste and Recycling Department, Ministry of the Environment" means that the calculation includes these prerequisites. An example of calculating carbon dioxide emissions is described below. The acceptable range of carbon dioxide emissions is 6.0 g / m 2 The following is the result. Non-patent document 1: https: / / www.env.go.jp / press / files / jp / 19747.pdf

[0107] [1.8] Uneven distribution of filling The sound-absorbing material was cut to obtain a test piece. The size of the test piece was 250 mm wide x 250 mm long x 50 mm thick. The test piece was placed vertically between wall surfaces spaced 60 mm apart. In this state, the sound-absorbing material was visually inspected to determine if wrinkles or unevenness appeared on the surface of the sound-absorbing material when it was installed on a sound-absorbing panel, indicating that the filling was unevenly distributed.

[0108] [1.9] Thickness change after padding punching The batting was cut to obtain a test piece. The size of the test piece was 250 mm wide x 250 mm long x 50 mm thick. Thickness 1 of the batting was measured before press processing. Using a Thomson blade with a blade diameter of 100 mm and a thickness of 37 mm, the batting was pressed in a room temperature press to cut out a cylinder with a diameter of 100 mm. Thickness 2 of the batting after press processing was measured. The value obtained by subtracting thickness 1 from thickness 2 was taken as the "change in thickness after punching processing." A positive value means that the thickness increased due to press processing.

[0109] [1.10] Hollow ratio of hollow fibers in spunbond nonwoven fabrics The hollow fibers of the spunbond nonwoven fabric were embedded in epoxy resin and then cut using a microtome to obtain sample pieces. The sample pieces were observed using an electron microscope (manufactured by Hitachi, Ltd., model SU3500). The cross-sectional area of ​​the entire fiber and the cross-sectional area of ​​the hollow portion in the observed fiber cross-sectional image were calculated from the obtained cross-sectional image. The value calculated using the following formula (3) was taken as the "hollow ratio." Formula (3): Hollow ratio [%] = (cross-sectional area of ​​hollow part / cross-sectional area of ​​entire fiber) × 100 The hollowness ratio was calculated as the average value of measurements taken on 100 fibers.

[0110] [2] Examples and Comparative Examples [2.1] Preparation The fibers that make up the filling are as follows: Fiber 1: Solid short fiber of polypropylene polymer (manufactured by Ube Exsymo Co., Ltd., product name: UC Fiber, average fiber diameter 21 μm, 2 denier, average fiber length 51 mm) Fiber 2: Solid short fiber of polyethylene terephthalate resin (manufactured by Unitika Ltd., product name: Melty 4080 (adhesive fiber), 2 denier, average fiber diameter 14 μm, average fiber length 51 mm) Fiber 3: Solid staple fiber (average fiber diameter 25 μm, 6 denier, average fiber length 51 mm) containing 30% to 70% polyethylene terephthalate recycled resin derived from recycled PET bottles Fiber 4: Solid short fiber of polyethylene terephthalate resin (average fiber diameter 25 μm, 6 denier, average fiber length 51 mm) Fiber 5: Polyethylene terephthalate recycled resin hollow short fiber (average fiber diameter 33 μm, 6 denier, hollow ratio 28%, recycled fiber, average fiber length 51 mm) Fiber 6: Polyethylene terephthalate recycled resin hollow short fiber (average fiber diameter 45 μm, 14 denier, hollow ratio 28%, recycled fiber, average fiber length 51 mm) Fiber 7: Solid staple fiber (average fiber diameter 45 μm, 20 denier, average fiber length 51 mm) containing 30% to 70% polyethylene terephthalate recycled resin from recycled PET bottles

[0111] [2.2] Example 1 [2.2.1] Preparation of skin material A propylene homopolymer having an MFR of 60 g / 10 min was melt-spun at 230°C by a conventional spunbonding method using a spunbond nonwoven fabric molding machine having a spinneret with a diameter of 0.6 mm, and the fibers obtained by spinning were deposited on a collecting surface to obtain a first spunbond web. The average fiber diameter of the first spunbond web was 13 μm. The basis weight of the first spunbond web was 10 g / m 2 It was.

[0112] Next, a propylene homopolymer with an MFR of 400 g / 10 min was melted at 280°C using an extruder, and the resulting melt was extruded from a spinneret and heated at 280°C by a conventional meltblowing method in which air was blown onto the first spunbond web to form a meltblown web. The average fiber diameter of the meltblown web was 3 μm. The basis weight of the meltblown web was 5 g / m2 It was.

[0113] Next, fibers were deposited on the meltblown web in the same manner as in the first spunbond web to form a second spunbond web. The average fiber diameter of the second spunbond web was 13 μm. The basis weight of the second spunbond web was 10 g / m 2 This resulted in a first laminate. The first laminate was formed by laminating a first spunbond web, a meltblown web, and a second spunbond web in this order.

[0114] The first laminate was sandwiched between an embossing roll and a mirror roll to form a three-layer (SMS) nonwoven fabric (surface material) (hereinafter also referred to as "SMS structure nonwoven fabric"). The set temperature of the embossing roll was 145°C. The set temperature of the mirror roll was 150°C. The imprint area ratio of the embossing roll was 18%. The embossed pattern of the embossing roll was 0.9 mm square. The SMS structure nonwoven fabric was formed by laminating a first spunbond nonwoven fabric, a meltblown nonwoven fabric, and a second spunbond nonwoven fabric in this order. The first spunbond nonwoven fabric was the same as the first spunbond web except that it did not have an embossed portion. The meltblown nonwoven fabric was the same as the meltblown web except that it did not have an embossed portion. The second spunbond nonwoven fabric was the same as the second spunbond web except that it did not have an embossed portion. The basis weight of the SMS structure nonwoven fabric is 25g / m 2 It was.

[0115] Next, a propylene homopolymer having an MFR of 60 g / 10 min was melt-spun at 230°C by a conventional spunbonding method using a spunbond nonwoven fabric molding machine with a spinneret having a diameter of 1.3 mm, and the fibers obtained by the spinning were deposited on the SMS structure nonwoven fabric to form a third spunbond web. The average fiber diameter of the third spunbond web was 35 μm. The basis weight of the third spunbond web was 100 g / m 2This resulted in a second laminate. The second laminate consisted of the SMS structural nonwoven fabric and a third spunbond web. The third spunbond web was in contact with the second spunbond nonwoven fabric side of the SMS structural nonwoven fabric.

[0116] Next, the second laminate was sandwiched between an embossing roll and a mirror roll to be integrated, obtaining a four-layer structure (SSMS structure) nonwoven fabric (skin material). The set temperature of the embossing roll was 155°C. The set temperature of the mirror roll was 160°C. The imprint area ratio of the embossing roll was 18%. The embossed pattern of the embossing roll was 0.9 mm square. The skin material was formed by laminating a first spunbond nonwoven fabric, a meltblown nonwoven fabric, a second spunbond nonwoven fabric, and a third spunbond nonwoven fabric in this order. The third spunbond nonwoven fabric was the same as the third spunbond web, except that an embossed portion was not formed. The basis weight of the skin material was 125 g / m 2 The carbon dioxide emissions from the skin material were 0.7 kg / m 2 It was.

[0117] [2.2.1.1] Calculating carbon dioxide emissions from skin materials The carbon dioxide emissions from the skin material were calculated as follows based on the carbon dioxide emissions from crude oil extraction to resin production per 1 kg of nonwoven fabric and polyolefin fiber containing the polypropylene resin fiber, the carbon dioxide emissions per kg of nonwoven fabric containing polypropylene resin fiber when incinerated, and the public reference number JP212022 of the "Carbon Footprint System Pilot Project CO2 Equivalent Common Basic Unit Database ver. 4.01 (Domestic Data)." The carbon dioxide emissions from a skin material using, for example, polypropylene-based fibers as the thermoplastic resin were calculated using the following formula (4). Formula (4): Carbon dioxide emissions from skin materials using polypropylene-based fibers = [(carbon dioxide emissions from crude oil extraction to resin production per 1 kg of nonwoven fabric containing the polypropylene-based resin fiber) + (carbon dioxide emissions during incineration per 1 kg of nonwoven fabric containing the polypropylene-based resin fiber) + (carbon dioxide emissions based on the public reference number JP212022 of the "Carbon Footprint System Pilot Project CO2 Equivalent Common Basic Unit Database ver. 4.01 (Domestic Data)")] × basis weight / 1000

[0118] [2.2.2] Preparation of adhesive area A spray adhesive (such as a hot melt adhesive, an acrylic adhesive, a urethane adhesive, or an olefin adhesive) was applied to the entire surface of the first spunbond nonwoven fabric layer of the skin material, thereby obtaining a skin material with adhesive portions.

[0119] [2.2.3] Preparation of sound-absorbing material Five parts by mass of fiber 1, 35 parts by mass of fiber 2, 30 parts by mass of fiber 5, and 30 parts by mass of fiber 6 were mixed, and a web was formed using a fiber opener and then a carding machine.The carded web was then multilayered onto the adhesive portion of the adhesive-attached skin material using a cross-layering machine, resulting in a third laminate.The carded web contained short fibers of a polypropylene-based polymer and short fibers of a polyethylene terephthalate-based resin. The third laminate was treated with a hot air treatment machine set to a gap distance of approximately 50 mm to produce a filling on the skin material with the adhesive portion. In other words, a sound-absorbing material (see Figure 1) was obtained. The sound-absorbing material was a sheet-like material. The sound-absorbing material was made by laminating the skin material, adhesive portion, and filling in this order. The filling was a carded nonwoven fabric. The filling was similar to a carded web except that the short fibers were not fused together by the hot air treatment machine. The sound-absorbing material had a thickness of approximately 50 mm.

[0120] [2.2.3.1] Calculating carbon dioxide emissions from padding The carbon dioxide emissions from the filling using polypropylene-based fibers and polyester-based resin fibers were calculated using the following formula (5). Formula (5): Carbon dioxide emissions from batting using polypropylene fiber and polyester resin fiber = [(carbon dioxide emissions from crude oil extraction to resin production per 1 kg of the polypropylene resin fiber) + (carbon dioxide emissions at incineration per 1 kg of the polypropylene resin fiber) + (carbon dioxide emissions based on the public reference number JP212022 of the "Carbon Footprint System Pilot Project Common Basic Unit Database for CO2 Equivalents ver. 4.01 (Domestic Data)")] × basis weight of batting × [content of polypropylene resin fiber in batting (mass%)] / 1000 + [(carbon dioxide emissions from crude oil extraction to resin production per 1 kg of the polyester resin fiber) + (carbon dioxide emissions at incineration per 1 kg of the polyester resin fiber) + (carbon dioxide emissions based on the public reference number JP212024 of the "Carbon Footprint System Pilot Project Common Basic Unit Database for CO2 Equivalents ver. 4.01 (Domestic Data)")] × basis weight of batting × [content of polyester resin fiber in batting (mass%)] / 1000

[0121] [2.3] Examples 2 to 7 and Comparative Examples 1 to 5 Sound-absorbing materials were produced in the same manner as in Example 1, except that the basis weight of the padding and the fibers used in producing the padding were changed as shown in Table 1, and the physical properties and performance of the sound-absorbing materials were measured or calculated. The results are shown in Table 1.

[0122] [2.4] Example 8 [2.4.1] Making the filling The basis weight of the batting and the fibers used to prepare the batting are as shown in Table 1. The batting was prepared on the collection surface in the same manner as in Example 1, except that 5 parts by mass of fiber 1, 30 parts by mass of fiber 2, 50 parts by mass of fiber 5, and 15 parts by mass of fiber 7 were mixed. The batting was a carded nonwoven fabric containing short fibers of a polypropylene-based polymer and short fibers of a polyethylene terephthalate-based resin. The thickness of the batting was approximately 50 mm.

[0123] [2.4.2] Fabrication of a sound-absorbing material in the form of a pouch A sheet of skin material (a nonwoven fabric with a four-layer structure (SSMS structure)) was prepared in the same manner as in Example 1. The batting was cut to a size of 250 mm (length) × 250 mm (width) × 50 mm (thickness). Next, the cut batting was placed between the skin material folded in two. The skin material was placed so that the third spunbond nonwoven fabric side of the skin material (SSMS structure nonwoven fabric) was the outermost surface (the side not facing the batting). The periphery of the batting of the skin material folded in two was fused using an ultrasonic sealing machine (manufactured by Seidensha Electronics Co., Ltd., product name: JII430SA) to form a continuous sealed portion. The fusion conditions were an output of 2.0 V, a pressure of 0.3 MPa, and a speed of 5 m / min. The width of the sealed portion was 0.3 mm. This resulted in a sound-absorbing material (see FIG. 2) in which the batting was encapsulated in the skin material. The excess part around the outer periphery of the seal was cut off. The physical properties and performance of the sound-absorbing material were measured, and the results are shown in Table 1.

[0124] [Table 1]

[0125] In Table 1, "solid" refers to solid staple fibers. "hollow" refers to hollow staple fibers. "CO2 emissions" refers to the amount of carbon dioxide emissions. "Thickness change" refers to the amount of thickness change after the padding punching process is carried out. "Content" refers to the amount of padding content (mass%) relative to the total amount of sound-absorbing material. "Total CO2 emissions" refers to the sum of the carbon dioxide emissions of the skin material and the padding.

[0126] [3] Results [3.1] Comparative Examples 1 to 5 The filling of Comparative Example 1 was not a nonwoven fabric containing hollow fibers and solid fibers. The total surface area of ​​Comparative Examples 2 to 4 was 160 m 2 / m 2 Super 270m 2 / m 2 The sum of the sound absorption coefficients of Comparative Examples 1 to 4 was not within the range below: Therefore, the sum of the sound absorption coefficients of Comparative Examples 1 to 4 was not 12.10 or more. As a result, it was found that the sound-absorbing materials of Comparative Examples 1 to 4 were not "sound-absorbing materials that emit little carbon dioxide during production, etc., but do not have a high sound absorption coefficient." The basis weight of the sound absorbing material of Comparative Example 5 is 2000 g / m 2 The ratio (filling / surface material) of Comparative Example 5 was not less than 10. The bulk density of the filling of Comparative Example 5 was 37 kg / m 3 The total surface area of ​​Comparative Example 5 was 160 m 2 / m 2 Super 270m 2 / m 2 Therefore, the amount of carbon dioxide emitted during the production of Comparative Example 5 was 6.0 g / m 2 As a result, the sound-absorbing material of Comparative Example 5 is a conventional type of sound-absorbing material, and is a sound-absorbing material with a sound absorption rate appropriate for the purpose, but the amount of resin used in the sound-absorbing material is large (the basis weight of the sound-absorbing material is 2000 g / m 2 Therefore, it was found that this is a sound-absorbing material that emits a relatively high amount of carbon dioxide during manufacturing.

[0127] [3.2] Examples 1 to 8 The sound-absorbing materials of Examples 1 to 8 were provided with padding and a skin material arranged on the outermost side. The sound-absorbing material had a basis weight of 2000 g / m 2 The ratio (filling / surface material) was less than 10. The thickness of the filling was 40 mm or more. The bulk density of the filling was 37 kg / m 3 The filling was a nonwoven fabric containing hollow fibers and solid fibers having an average fiber diameter different from that of the hollow fibers. The total surface area was less than 160 m 2 / m 2 Super 270m 2 / m 2 It was as follows. Therefore, the amount of carbon dioxide emitted during the production of Examples 1 to 8 was 6.0 g / m 2 The total sound absorption coefficient of Examples 1 to 8 was 12.10 or more. As a result, it was found that the sound-absorbing materials of Examples 1 to 8 are "sound-absorbing materials with low carbon dioxide emissions during manufacturing etc. and high sound absorption coefficients." [Explanation of symbols]

[0128] 1 sound absorbing material, 2 padding, 3 skin material, 4 sealing portion, 11 sound absorbing panel, 12 shielding plate, 13 side wall, 14 frame, 15 protection panel, 16 support portion

Claims

1. A sound-absorbing material comprising a padding and a skin material disposed on the outermost side, The basis weight of the sound absorbing material is 2000 g / m ２ is as follows: The total surface area per unit area of ​​the skin material (m ２ / m ２ ) to the total surface area per unit area of ​​the filling (m ２ / m ２ ) is less than 10; The thickness of the padding is 40 mm or more, The bulk density of the filling is 37 kg / m ３ is less than the filling is a nonwoven fabric containing thermoplastic resin hollow fibers and thermoplastic resin solid fibers having an average fiber diameter different from the average fiber diameter of the thermoplastic resin hollow fibers, The sum of the surface areas of the outer diameters of the fibers constituting the filling per unit area of ​​the filling is 160 m ２ / m ２ super 270m ２ / m ２ is as follows: The sound-absorbing material, wherein the skin material is a nonwoven fabric containing thermoplastic resin fibers.

2. 2. The sound-absorbing material according to claim 1, wherein the thermoplastic resin hollow fibers have an average fiber diameter of 20 μm to 50 μm.

3. 3. The sound-absorbing material according to claim 2, wherein the content of the thermoplastic resin hollow fibers having an average fiber diameter of 20 μm to 50 μm relative to the total amount of the padding is 25% by mass to 60% by mass.

4. The sound-absorbing material according to claim 3 , wherein the padding further comprises solid thermoplastic resin fibers having an average fiber diameter of 10 μm or more and less than 20 μm.

5. The sound-absorbing material according to claim 3 , wherein each of the thermoplastic resin hollow fibers and the thermoplastic resin solid fibers comprises one of a polypropylene-based resin and a polyester-based resin.

6. At least one of the thermoplastic resin hollow fibers and the thermoplastic resin solid fibers contains the polyester-based resin, 6. The sound-absorbing material according to claim 5, wherein the polyester resin comprises recycled polyethylene terephthalate.

7. the skin material includes a first spunbond nonwoven fabric, a meltblown nonwoven fabric adjacent to the first spunbond nonwoven fabric, a second spunbond nonwoven fabric adjacent to the meltblown nonwoven fabric, and a third spunbond nonwoven fabric adjacent to the second spunbond nonwoven fabric; 2. The sound-absorbing material according to claim 1, wherein the third spunbond nonwoven fabric contains thermoplastic resin fibers having an average fiber diameter of 25 μm to 50 μm.

8. 8. The sound-absorbing material of claim 7, wherein at least one of the first spunbond nonwoven, the meltblown nonwoven, and the third spunbond nonwoven comprises thermoplastic hollow fibers.

9. The sound-absorbing material according to claim 1 , further comprising an adhesive portion that joins the padding and the surface material.

10. The carbon dioxide emission of the skin material and the padding is 6.0 kg / m ２ is as follows:

2. The sound-absorbing material according to claim 1, wherein the carbon dioxide emissions represent a calculated value obtained by calculating in accordance with the 3R basic unit calculation method reported by the Recycling-Based Society Promotion Office, Planning Division, Waste Management and Recycling Department, Ministry of the Environment.

11. A sound-absorbing panel comprising the sound-absorbing material according to any one of claims 1 to 10 and a frame that houses the sound-absorbing material.

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