Railroad sound absorption material, railroad sound absorption panel and manufacturing method of railroad sound absorption material

Abstract

To provide a railroad sound absorption material and a railroad sound absorption panel, which reuse a polyethylene terephthalate container which has a relatively high impurity content, is made from polyethylene terephthalate and is discharged and collected from railway-related businesses and to provide a manufacturing method of the railroad sound absorption material.SOLUTION: An inner cotton of a railroad sound absorption material 1 formed of the inner cotton 2 and a skin material 3 containing the inner cotton is a nonwoven fabric containing polyethylene terephthalate fibers. The polyethylene terephthalate fiber contains at least one impurity selected from a group consisting of polyolefin, polystyrene and polyvinylchloride, the content of the impurity in the polyethylene terephthalate fiber is in the range of 0.0005 to 0.5 mass%, and the average fiber diameter of the polyethylene terephthalate fiber is in the range of 1.0 to 30 dtex.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a railway sound-absorbing material, a railway sound-absorbing panel, and a method for manufacturing a railway sound-absorbing material. [Background technology]

[0002] There is known a sound absorbing material that is made of a filling material containing fibers made of at least polyester resin and a skin material that contains the filling material, and the skin material is made of a nonwoven fabric containing fibers made of polypropylene resin (see, for example, Patent Document 1). The sound absorbing material is unlikely to lose its sound absorption coefficient even in a moist environment.

[0003] On the other hand, PET bottles are collected at various places in order to reuse the polyethylene terephthalate that constitutes them. The recycled polyethylene terephthalate obtained by reusing the collected PET bottles contains impurities. The impurities come from polyolefin or polystyrene labels attached to the PET bottles, polyolefin caps, leftover drinks, polyvinyl chloride bottles collected together with the PET bottles, and the like. The recycled polyethylene terephthalate obtained by reusing the PET bottles discharged and collected from railway-related businesses contains more impurities than the recycled polyethylene terephthalate obtained by reusing the PET bottles collected by local governments. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] International Publication No. 2021 / 251279 Summary of the Invention [Problem to be solved by the invention]

[0005] Recycled polyethylene terephthalate containing impurities has various properties that are degraded. Therefore, there has been a tendency to avoid recycled polyethylene terephthalate obtained by reusing PET bottles discharged and collected from railway-related businesses. It was thought that it would be difficult to use recycled polyethylene terephthalate obtained by reusing PET bottles discharged and collected from railway-related businesses, which contains a relatively large amount of the above-mentioned impurities, as a raw material for sound-absorbing materials.

[0006] Therefore, the problem that the present invention aims to solve is to provide a railway sound-absorbing material made from polyethylene terephthalate, which has a relatively high content of the impurities, a railway sound-absorbing panel comprising the railway sound-absorbing material, and a method for manufacturing the railway sound-absorbing material by reusing polyethylene terephthalate containers discarded and collected from railway-related businesses. [Means for solving the problem]

[0007] The present inventors have conducted extensive research in light of the above problems and have found that the low-temperature impact resistance of recycled polyethylene terephthalate obtained by reusing PET bottles discharged and collected from railway-related businesses, which contain a relatively large amount of the above-mentioned impurities, is higher than that of virgin polyethylene terephthalate. The present invention has been completed based on these findings.

[0008] The present invention relates to a railway sound-absorbing material comprising a filling and a skin material containing the filling, the filling being a nonwoven fabric containing polyethylene terephthalate fibers, the polyethylene terephthalate fibers containing at least one impurity selected from the group consisting of polyolefins, polystyrene, and polyvinyl chloride, the content of the impurity in the polyethylene terephthalate fibers being in the range of 0.0005 to 0.5 mass%, and the polyethylene terephthalate fibers having an average fiber diameter in the range of 1.0 to 30 dtex. The polyolefin preferably includes at least one selected from the group consisting of polyethylene and polypropylene. The skin material is preferably a skin material comprising a first spunbond nonwoven fabric, a meltblown nonwoven fabric adjacent to the first spunbond nonwoven fabric, and a second spunbond nonwoven fabric adjacent to the meltblown nonwoven fabric, or a skin material comprising 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. At least one selected from the group consisting of the first spunbond nonwoven fabric, the second spunbond nonwoven fabric, and the third spunbond nonwoven fabric preferably contains fibers having an average fiber diameter in the range of 25 to 50 μm. The meltblown nonwoven fabric preferably contains fibers having an average fiber diameter in the range of 0.5 to 5 μm. At least one selected from the group consisting of the first spunbond nonwoven fabric, the second spunbond nonwoven fabric, and the third spunbond nonwoven fabric preferably contains hollow fibers.

[0009] The present invention also relates to a railway sound-absorbing panel comprising the railway sound-absorbing material and a frame for housing the railway sound-absorbing material.

[0010] The present invention further relates to a method for producing the railway sound-absorbing material, comprising a compression step of compressing polyethylene terephthalate containers discharged and collected from railway-related businesses, a crushing step of crushing the compressed material obtained in the compression step, and a fiberization step of fiberizing the recycled polyethylene terephthalate flakes obtained in the crushing step, wherein the recycled polyethylene terephthalate fibers obtained in the fiberization step contain at least one impurity selected from the group consisting of polyolefins, polystyrene, and polyvinyl chloride, the content of the impurity in the recycled polyethylene terephthalate fibers is in the range of 0.0005 to 0.5 mass%, and the average fiber diameter of the recycled polyethylene terephthalate fibers is in the range of 1.0 to 30 dtex. Effect of the Invention

[0011] The railway sound-absorbing material of the present invention provides a railway sound-absorbing material made from polyethylene terephthalate having a relatively high content of the impurities.The railway sound-absorbing panel of the present invention provides a railway sound-absorbing panel including the railway sound-absorbing material and a frame for housing the railway sound-absorbing material.The railway sound-absorbing material manufacturing method of the present invention provides a method for manufacturing a railway sound-absorbing material using recycled polyethylene terephthalate containers discarded and collected from railway-related businesses. [Brief description of the drawings]

[0012] [Figure 1] 1 is a cross-sectional view of a first embodiment of a sound-absorbing material. [Diagram 2] FIG. 4 is a cross-sectional view of a second embodiment of the sound absorbing material. [Diagram 3] 1 is a cross-sectional view of one embodiment of an acoustical panel. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] The present invention will now be described in further detail. In addition, unless otherwise specified, "~" in a numerical range means from above to below, and both ends of the range are included. In addition, when a numerical range is indicated, the upper limit and the lower limit can be appropriately combined, and the numerical range obtained by combining them is also disclosed. In addition, in the description of the drawings, the same elements are denoted by the same reference numerals, and duplicated description will be omitted. Also, the dimensional ratios of the drawings are exaggerated for the convenience of explanation, and may differ from the actual ratios.

[0014] 1 is a cross-sectional view of a first embodiment of a railway sound-absorbing material (hereinafter, sometimes referred to as "sound-absorbing material") of the present invention. The sound-absorbing material 1 of this embodiment is composed of a filling 2 and a single sheet of skin material 3 that is provided on both the front and back sides (upper and lower layers) of the filling 2 and contains the filling 2. The filling 2 is sandwiched between the skin material 3 that is folded in two, and the skin material 3 has seal parts 4 on three sides of its periphery. As a result, the filling 2 is surrounded by the folded parts of the skin material 3 and the seal parts 4, and is contained in the skin material 3.

[0015] It should be noted that the filling 2 needs to be enclosed within the skin material 3, and the configuration in which the filling 2 is enclosed within the skin material 3 is not limited to the configuration shown in FIG.

[0016] For example, as in the second embodiment of the sound-absorbing material of the present invention shown in Figure 2, it may be configured to consist of a filling 2 and two skin materials 3, 3 that are provided on both the front and back sides (upper and lower layers) of the filling 2 and encase the filling 2, and the skin materials 3, 3 have a sealing portion 4 on their peripheral edges that surrounds the filling 2.

[0017] The basis weight of the sound-absorbing material 1 is set to 500 to 3000 g / m from the viewpoint of further improving the sound absorption coefficient mainly in the range of 100 to 2000 Hz and preventing a decrease in workability due to an increase in the weight of the sound-absorbing material. 2 The range is preferably 1000 to 2500 g / m 2 More preferably, the range is 1300 to 2200 g / m 2 It is more preferable that the range is .

[0018] The thickness of the sound-absorbing material 1 is preferably in the range of 10 to 100 mm, and more preferably in the range of 20 to 70 mm, from the viewpoints of further improving the sound absorption coefficient in the low frequency range, particularly in the range of 100 to 1000 Hz, and of ensuring efficient space when installing it in a structure or the like.

[0019] <Padding> The sound-absorbing material of the present invention includes a padding. The padding is a nonwoven fabric containing polyethylene terephthalate fibers. The polyethylene terephthalate constituting the polyethylene terephthalate fibers may be virgin polyethylene terephthalate or recycled polyethylene terephthalate. The polyethylene terephthalate fibers are preferably made of recycled polyethylene terephthalate.

[0020] The polyethylene terephthalate fibers contain at least one impurity selected from the group consisting of polyolefins, polystyrene, and polyvinyl chloride.

[0021] (Polyolefin) As the polyolefin, a wide variety of ordinary polyolefins that can be used as labels or caps for polyethylene terephthalate containers can be used. The polyolefins also include olefin-based elastomers. In order to achieve the effects of the present invention, it is preferable to adjust the content of polyethylene as an impurity among the polyolefins. Although the mechanism of action is unclear, it is thought that the polyethylene impurity acts as a nucleus to affect the crystallization of the polyethylene terephthalate fiber when it is spun.

[0022] Examples of the polyolefin include homopolymers or copolymers of α-olefins having 2 to 20 carbon atoms, such as ethylene, propylene, 1-butene, 1-hexene, and 4-methyl-pentene. Also included are copolymers of α-olefins and non-conjugated dienes having 2 to 20 carbon atoms, such as dicyclopentadiene, 1,4-hexadiene, cyclooctadiene, methylenenorbornene, ethylidenenorbornene, butadiene, and isoprene. Also included are ethylene-α-olefin copolymer rubber, ethylene-α-olefin-non-conjugated diene copolymer rubber, propylene-α-olefin copolymer rubber, and butene-α-olefin copolymer rubber. In addition, ethylene-(meth)acrylic acid copolymer, ethylene-(meth)acrylic acid ester-(meth)acrylic acid copolymer, ethylene-vinyl acetate copolymer, ethylene-vinyl acetate-(meth)acrylic acid copolymer, ethylene-propylene-(meth)acrylic acid copolymer, ethylene-propylene-(meth)acrylic acid ester-(meth)acrylic acid copolymer, ethylene-maleic anhydride copolymer, ethylene-(meth)acrylic acid ester-maleic anhydride copolymer, ethylene-butene-(at least one of maleic anhydride and (meth)acrylic acid), propylene-butene-(at least one of maleic anhydride and (meth)acrylic acid), ethylene-vinyl chloride copolymer, ethylene-vinyl chloride copolymer, and ethylene-(meth)acrylic acid copolymer can also be used.

[0023] The olefin-based elastomer is called an olefin-based thermoplastic elastomer, and is an elastomer in which the hard segment is a polyolefin and the soft component is a rubber component. Examples of the elastomer include a blend type of the polyolefin and the rubber component, a dynamic crosslinking type, and a polymer type.

[0024] Examples of polyolefins in olefin-based elastomers include ethylene-propylene copolymers, ethylene-1-butene copolymers, ethylene-α-olefin copolymers, propylene-1-butene copolymers, propylene-α-olefin copolymers, 1-butene-α-olefin copolymers, propylene-1-butene-ethylene copolymers, propylene-α-olefin-ethylene copolymers, propylene-α-olefin-1-butene copolymers, 1-butene-α-olefin-ethylene copolymers, and polypropylene.

[0025] Examples of the rubber component in the olefin-based elastomer include isoprene rubber (IR), butadiene rubber (BR), chloroprene rubber (CR), butyl rubber (IIR, i.e., isobutylene-isoprene copolymer), propylene rubber (PP), ethylene-propylene rubber (EPM), and ethylene-propylene-diene rubber (EPDM). The olefin-based elastomer may contain one kind of polyolefin and one kind of rubber component, or may contain two or more kinds of them.

[0026] The polyolefins may be used alone or in combination of two or more kinds. The polyolefin preferably includes at least one homopolymer or copolymer selected from the group consisting of polyethylene and polypropylene, and more preferably is at least one homopolymer or copolymer selected from the group consisting of polyethylene and polypropylene.

[0027] (polystyrene) As the polystyrene, a wide variety of ordinary polystyrenes that can be used as labels for polyethylene terephthalate containers can be used. The polystyrene also includes polystyrene-butadiene copolymers, styrene-based thermoplastic elastomers, and hydrogenated polymers thereof.

[0028] The styrene-based thermoplastic elastomer or its hydrogenated product is not particularly limited, and examples thereof include styrene-ethylene-butylene-styrene block copolymer (SEBS), styrene-isoprene-styrene block copolymer (SIS), hydrogenated SIS, styrene-isobutylene-styrene block copolymer (SIBS), styrene-butadiene-styrene block copolymer (SBS), hydrogenated SBS, styrene-ethylene-ethylene-propylene-styrene block copolymer (SEEPS), styrene-ethylene-propylene-styrene block copolymer (SEPS), styrene-butadiene rubber (SBR), hydrogenated styrene-butadiene rubber (HSBR), and further random copolymers corresponding to each of the above block copolymers.

[0029] (Polyvinyl chloride) As the polyvinyl chloride, a wide range of ordinary polyvinyl chlorides that can be used as containers can be used.

[0030] The content of the impurities in the polyethylene terephthalate fibers is in the range of 0.0005 to 0.5% by mass. If the content is less than 0.0005% by mass, the low-temperature impact resistance of the railway sound-absorbing material becomes too low. If the content is more than 0.5% by mass, the various physical properties of the railway sound-absorbing material become too low.

[0031] The average fiber diameter of the polyethylene terephthalate fiber is in the range of 1.0 to 30 dtex. When the average fiber diameter is 1.0 dtex or more, the strength and rigidity of the filling are excellent, and when the filling is wrapped in a nonwoven fabric, the handling property is good. When the average fiber diameter is less than 1.0 dtex, it may be suitable for an embodiment in which the sound absorbing material is bent, but may be too soft depending on the required performance. When the average fiber diameter is 30 dtex or less, the specific surface area of ​​the nonwoven fabric after molding can be appropriately set, and the sound absorbing performance is excellent. When the average fiber diameter exceeds 30 dtex, the sound absorbing performance may decrease depending on the noise range. The average fiber diameter is preferably in the range of 1.5 to 25 dtex, more preferably in the range of 2.0 to 20 dtex.

[0032] For the spunbond nonwoven fabric, ten test pieces of 10 mm x 10 mm were taken, and the diameters of 20 arbitrary points for each test piece were read in μm units to the first decimal place at a magnification of 50 times using a microscope (Nikon Corporation, product name: ECLIPSE E400), and the average value was taken as the average fiber diameter.For the meltblown nonwoven fabric, the fiber diameters (μm) of 30 constituent fibers of the taken sample pieces were measured at a magnification of 500 times or 1000 times using a scanning electron microscope (Hitachi, Ltd., model name: SU3500), and the average value was taken as the average fiber diameter.

[0033] The filling may be in the form of a composite fiber, a modified fiber, a crimped fiber, a split fiber, etc., in which two or more polyethylene terephthalate compositions are combined. The filling may also contain a heat stabilizer, an ultraviolet absorbing agent, a weather stabilizer, a flame retardant, a water repellent, an oil agent, an antistatic agent, a colorant, an inorganic substance, etc.

[0034] As the filling, for example, a nonwoven fabric molded body containing polyester (polyethylene terephthalate) resin fibers, the recycled polyethylene terephthalate fibers containing impurities, and polypropylene resin fibers can be used.

[0035] The weight of the filling is set to 400 to 2900 g / m from the viewpoint of further improving the sound absorption coefficient mainly in the range of 100 to 2000 Hz and preventing a decrease in workability due to an increase in the weight of the sound absorbing material. 2 The range is preferably 900 to 2400 g / m 2 More preferably, the range is 1200 to 2100 g / m 2 From the viewpoint of reducing carbon dioxide emissions, the weight of the filling is preferably in the range of 1200 to 1800 g / m 2 From the viewpoint of ensuring the strength of the padding structure that supports the sound absorbing material, the weight of the padding is particularly preferably in the range of 1200 to 1400 g / m 2 It is most preferable that the range is 1. When the basis weight of the filling is small, the filling (resin) tends to be unevenly distributed due to its own weight, so it is particularly important to set the total surface area of ​​the outer diameter of the filling fibers per unit area, which will be described later, within a predetermined range.

[0036] The polyester (polyethylene terephthalate) resin fiber and the polypropylene resin fiber may be manufactured by a known melt spinning method, or may be purchased from the market. The polyester (polyethylene terephthalate) resin fiber may have an average fiber length in the range of 10 to 100 mm and an average fiber diameter in the range of 10 to 70 μm, and the polypropylene resin fiber may have an average fiber length in the range of 10 to 100 mm and an average fiber diameter in the range of 10 to 50 μm. The polyester (polyethylene terephthalate) resin fiber and the polypropylene resin fiber may have different average fiber diameters.

[0037] From the viewpoint of further improving the sound absorption coefficient, the ratio of polyester-based resin fibers to polypropylene-based resin fibers in the nonwoven fabric molding is preferably, on a mass basis, polyester-based resin fibers:polypropylene-based resin fibers in the range of 99:1 to 5:95, more preferably 95:5 to 10:90, and even more preferably 80:20 to 20:80.

[0038] The nonwoven fabric molding can be obtained, for example, by mixing 1 to 95% by mass, for example 20% by mass, of the polypropylene-based resin fibers, polyester (polyethylene terephthalate) binder fibers using 99 to 5% by mass, for example 30% by mass of a binder resin, and the recycled polyethylene terephthalate fibers containing impurities using 99 to 5% by mass, for example 50% by mass of a resin other than the binder resin, forming a web using a fiber spreader and then a carding machine, laminating the obtained web in multiple layers using a cross layer machine, and treating it with a hot air treatment machine set to a predetermined gap distance to fuse the polyester (polyethylene terephthalate)-based binder fibers and the polypropylene-based resin fibers.

[0039] The polypropylene-based resin may be a homopolymer of propylene, or a copolymer of propylene with other α-olefins copolymerizable with propylene. Examples of the α-olefin include α-olefins having 2 or more carbon atoms, preferably 2 to 8 carbon atoms, such as ethylene, 1-butene, 1-pentene, 1-hexene, 1-octene, and 4-methyl-1-pentene. When the polypropylene-based resin is a copolymer of propylene and an α-olefin, it may be a copolymer of one or more α-olefins selected from the α-olefins. The polypropylene-based resin may have an MFR (melt flow rate) in the range of, for example, 1 to 500 g / min.

[0040] The polyester (polyethylene terephthalate) binder fiber may be, for example, one having a polyethylene terephthalate core and a binder component in the sheath. The binder component may be a copolymer polyester made of terephthalic acid or an ester-forming derivative thereof, isophthalic acid or an ester-forming derivative thereof, a lower alcohol, or a polyalkylene glycol or a monoether thereof.

[0041] In order to obtain the effects of the present invention, when combining a plurality of fibers used in the filling, the sum of the surface areas of the outer diameters of the filling fibers per unit area of ​​the plurality of fibers used in the filling is set to a specific range. The sum of the surface areas of the outer diameters of the filling fibers per unit area of ​​the filling is, for example, 150 to 270 m 2 / m 2 , preferably 200 to 270 m 2 / m 2 The total surface area is 150 m 2 / m 2 If the total surface area is less than 270 m, the sound absorbing properties of the sound absorbing material will be reduced. 2 / m 2 If it is larger, the amount of carbon dioxide emitted during the production of the sound-absorbing material, etc., increases. In order to further improve the sound absorption coefficient mainly in the 100 to 2000 Hz range while reducing the amount of carbon dioxide emitted, it is important to satisfy the above numerical range.

[0042] The total surface area is calculated, for example, as follows. For each fiber constituting the filling, the surface area of ​​the outer diameter of the filling fiber per unit area of ​​the filling is calculated according to the following formula (1), and the sum of all fibers is taken as the total surface area. 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 the denier, the denier value listed in the fiber product specifications is used. 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) / 106 × 3.14 × 9000 (m) / denier (g) × basis weight (g / m 2 )×Content (mass%) / 100...(1)

[0043] In the filling with low carbon dioxide emission, a combination of multiple fibers having a specific average fiber diameter produces a better effect. The filling is preferably a nonwoven fabric containing fine fibers having an average fiber diameter of 10 μm or more and less than 20 μm, and at least one thermoplastic resin fiber selected from the group consisting of medium-thick fibers having an average fiber diameter of 20 to 30 μm, and very-thick fibers having an average fiber diameter of 40 to 50 μm. The inventors have found that a filling containing at least one fiber selected from the group consisting of the medium-thick fibers and the very-thick fibers in addition to the fine fibers can prevent uneven distribution of the filling (resin) more effectively than a filling containing only the fine fibers. Combining multiple fibers having a specific average fiber diameter is useful for obtaining good sound absorbing performance from a filling with low carbon dioxide emission.

[0044] At least one thermoplastic resin fiber selected from the group consisting of the medium-thick fibers and the extra-thick fibers more preferably includes hollow fibers. Hollow fibers tend to have a high degree of fiber orientation and high fiber strength, so that when reducing the basis weight of the sound-absorbing material or the filling, the hollow fibers contribute to ensuring the strength of the filling structure that supports the sound-absorbing material. The present inventors have found that it is particularly preferable to make part of the medium-thick fibers or the extra-thick fibers hollow fibers.

[0045] The filling preferably contains the recycled polyethylene terephthalate fiber containing impurities, and the content of the recycled polyethylene terephthalate fiber containing impurities in the filling is 30% by mass or more. When the content of the recycled polyethylene terephthalate fiber containing impurities in the filling is within the above range, the sound absorbing material has an appropriate balance of low-frequency impact properties, sound absorption coefficient, strength, and rigidity.

[0046] The filling preferably contains thermoplastic resin hollow fibers, and the content of the thermoplastic resin hollow fibers in the filling is 30% by mass or more. When the content of the thermoplastic resin hollow fibers in the filling is within the above range, the amount of resin used in the sound-absorbing material is reduced. In addition, even if the basis weight of the sound-absorbing material or the filling is reduced, the strength of the filling structure supporting the sound-absorbing material can be ensured.

[0047] The content (total) of the medium-thick fibers and the extra-thick fibers is preferably 25% by mass or more. This ensures the strength of the padding structure that supports the sound-absorbing material and prevents uneven distribution of the padding. The upper limit can be set appropriately depending on the required performance, but from the viewpoint of further improving the sound absorption coefficient, it is preferably less than 60% by mass, and more preferably 50% by mass or less.

[0048] Furthermore, the content of the fine fibers in the filling is preferably 50% by mass or more and 80% by mass or less. When the content of the fine fibers in the filling is within the above range, all of the following points are satisfied: improving the sound absorption coefficient mainly in the 100 to 2000 Hz range, preventing a decrease in workability due to an increase in the weight of the sound absorbing material, reducing carbon dioxide emissions, and further ensuring the strength of the filling structure supporting the sound absorbing material and the sound absorbing material. From these viewpoints, the content of the fine fibers in the filling is more preferably 55% by mass or more and 75% by mass or less.

[0049] The filling may include composite fibers, non-circular fibers, crimped fibers, split fibers, etc. The filling may also include heat stabilizers, ultraviolet absorbers, weather stabilizers, flame retardants, water repellents, oil agents, antistatic agents, colorants, inorganic substances, etc.

[0050] <Skin material> The skin material is made of a nonwoven fabric containing fibers made of a thermoplastic resin. From the viewpoint of preventing contact between the filling and water, the skin material preferably has a water pressure resistance in the range of 200 to 2000 mmH2O, more preferably has a water pressure resistance in the range of 200 to 500 mmH2O, further preferably has a water pressure resistance in the range of 250 to 450 mmH2O, and particularly preferably has a water pressure resistance in the range of 280 to 400 mmH2O. The water pressure resistance of the skin material can be further increased by at least one method selected from the group consisting of, for example, reducing the average fiber diameter of the fibers constituting the skin material, increasing the density of the skin material, using fibers made of a polypropylene resin, and increasing the basis weight of the skin material.

[0051] The air permeability of the skin material is set to 5 to 200 cm from the viewpoint of improving the water pressure resistance to prevent the contact between the padding and water and from the viewpoint of transmitting sound waves to the padding side to maintain a good sound absorption rate. 3 / cm 2 / sec, and preferably in the range of 7 to 150 cm 3 / cm 2 / sec, more preferably in the range of 10-50 cm 3 / cm 2 More preferably, the range is 1 / second.

[0052] The thickness of the skin material is preferably in the range of 0.1 to 1.5 mm, and more preferably in the range of 0.3 to 1.0 mm, from the viewpoints of further improving the water pressure resistance and further preventing contact between the filling and water, maintaining strength such as shot blast resistance, preventing a situation in which the thickness is so great that sound waves are difficult to transmit to the filling side, and preventing a situation in which the thickness is so great that the workability of ultrasonic sealing, etc. is reduced.

[0053] The average fiber diameter of the fibers located near the surface of the skin material (hereinafter sometimes referred to as surface fiber diameter) is preferably in the range of 10 to 100 μm from the viewpoint of ensuring the strength of the structure supporting the sound absorbing material, and is preferably in the range of 20 to 100 μm, more preferably in the range of 25 to 50 μm, from the viewpoint of further improving shot blast resistance and controlling the air permeability within an appropriate range. Also, from the viewpoint of further improving shot blast resistance, it is particularly preferable that the surface fiber diameter of the fibers made of polypropylene resin is in the above range.

[0054] The polypropylene-based resin used in the nonwoven fabric constituting the skin material may be a homopolymer of propylene or a copolymer of propylene and other α-olefins copolymerizable with propylene. As the α-olefin, one or more α-olefins are used.

[0055] The fibers constituting the skin material may contain heat stabilizers, ultraviolet absorbers, weather stabilizers, flame retardants, water repellents, oil agents, antistatic agents, colorants, inorganic substances, and the like.

[0056] The polypropylene resin used in the nonwoven fabric constituting the skin material may have an MFR (melt flow rate) in the range of, for example, 10 to 100 g / min. In the sound-absorbing material 1, the skin material 3 has a water pressure resistance in the above range, and the inside is sealed with the sealing portion 4, so that the padding 2 does not come into contact with water, and the sound absorption rate is unlikely to decrease even in a humid environment.

[0057] The skin material may be a single layer of nonwoven fabric, or a laminated nonwoven fabric in which a plurality of nonwoven fabrics are laminated. The nonwoven fabric constituting the skin material 3 is not limited to a specific nonwoven fabric, and may be at least one selected from the group consisting of spunbonded nonwoven fabric and meltblown nonwoven fabric. From the viewpoint of further improving the strength such as shot blast resistance as a sound absorbing material, the skin material preferably contains at least one layer of spunbonded nonwoven fabric. Also, from the viewpoint of controlling the water pressure resistance and air permeability within a preferred range, it is preferable to contain at least one layer of meltblown nonwoven fabric. The spunbonded nonwoven fabric and the meltblown nonwoven fabric are distinguished by the average fiber diameter. In an embodiment of the present specification, the average fiber diameter of the spunbonded nonwoven fabric may be in the range of 10 to 100 μm, and the average fiber diameter of the meltblown nonwoven fabric may be in the range of 0.5 to 5 μm.

[0058] The smaller (thinner) the average fiber diameter of the fibers constituting the nonwoven fabric contained in the skin material, the denser the skin material is and the better its water pressure resistance. On the other hand, from the viewpoint of abrasion resistance (shot blast resistance) against the impact of solid objects such as hail, sleet, and pebbles, it is desirable for the average fiber diameter of the fibers to be large (thick). In addition, the average fiber diameter of the fibers contained in spunbond nonwoven fabrics is larger than the average fiber diameter of the fibers contained in meltblown nonwoven fabrics.

[0059] Therefore, the skin material may have at least a three-layer structure (hereinafter, the three-layer structure may be referred to as an SMS structure or a PP-SMS structure) of, for example, a first spunbond nonwoven fabric containing fibers made of a polypropylene resin having an average fiber diameter in the range of 10 to 50 μm, a meltblown nonwoven fabric containing fibers made of a polypropylene resin having an average fiber diameter in the range of 0.5 to 5 μm located on the first spunbond nonwoven fabric, and a second spunbond nonwoven fabric containing fibers made of a polypropylene resin having an average fiber diameter in the range of 10 to 50 μm located on the meltblown nonwoven fabric. The skin material may further include a third spunbond nonwoven fabric containing fibers made of a polypropylene resin having an average fiber diameter in the range of 25 to 50 μm. Alternatively, the skin material may be composed of only one of the spunbond nonwoven fabric layers of the first to third spunbond nonwoven fabrics. Here, "consisting only of a spunbond nonwoven fabric layer" means that it does not include nonwoven fabrics manufactured by other manufacturing methods, such as meltblown nonwoven fabrics, and does not exclude the inclusion of multiple layers of the same or different spunbond nonwoven fabrics.

[0060] When the skin material 3 has a structure of at least three layers, the average fiber diameter of the meltblown nonwoven fabric forming the inner layer is small and dense, thereby ensuring the water pressure resistance within the above range. On the other hand, since the average fiber diameter of the fibers contained in the meltblown nonwoven fabric is small, the meltblown nonwoven fabric may be prone to fluffing and may have poor shot blast resistance, so by using the first or second spunbond nonwoven fabric as the outer layer, the meltblown nonwoven fabric can be protected and tends to have better shot blast resistance.

[0061] Furthermore, the skin material 3 may have at least a four-layer structure (hereinafter, the four-layer structure may be referred to as an SSMS structure or a PP-SMSS structure) including a third spunbond nonwoven fabric containing fibers having an average fiber diameter in the range of 10 to 100 μm located on the second spunbond nonwoven fabric. By providing the third spunbond nonwoven fabric on the outermost surface, the skin material 3 can obtain better shot blast resistance. The third spunbond nonwoven fabric has, for example, an average fiber diameter in the range of 25 to 50 μm and a basis weight of 70 to 150 g / m. 2 From the viewpoints of further improving the sound absorption coefficient mainly in the 100 to 2000 Hz range, preventing a decrease in workability due to an increase in the weight of the sound-absorbing material, reducing carbon dioxide emissions, and further ensuring the strength of the padding structure that supports the sound-absorbing material and the sound-absorbing material, it is preferable to use a third spunbond nonwoven fabric in the above-mentioned range that uses fibers made of a polypropylene-based resin.

[0062] In addition, when the skin material 3 is composed of only a spunbond nonwoven fabric layer, for example, the average fiber diameter is in the range of 10 to 100 μm and the basis weight is in the range of 70 to 200 g / m 2 By including any one of the first to third spunbond nonwoven fabrics in the range, it is possible to achieve both the water pressure resistance and the sound absorption coefficient in the range. The spunbond nonwoven fabric layer may be composed of a single layer or multiple layers of the third spunbond nonwoven fabric, and another spunbond nonwoven fabric may be laminated on the third spunbond nonwoven fabric.

[0063] In addition, when the skin material 3 is composed of only a spunbonded nonwoven fabric layer, the average fiber diameter of the fibers located near the surface (hereinafter, sometimes referred to as the surface fiber diameter) tends to be in the range of 20 to 100 μm, for example, in the range of more than 30 μm and not more than 50 μm, so that excellent shot blast resistance can be obtained. In the spunbonded nonwoven fabric layer, for example, by setting the temperature of the embossing roll in the range of 140 to 170 ° C. and the temperature of the mirror roll in the range of 140 to 170 ° C. and performing embossing (thermocompression processing) to set the welding area ratio to 15% or more, the surface fiber diameter can be set to the above range, and the fusion between fibers in the non-embossed part is promoted, so that the apparent fiber diameter becomes thick. For the same reason, the welding area ratio during embossing can be set to 20% or more, or a large embossing pattern of 0.7 mm square or more can be used even with the same welding area ratio, thereby improving the shot blast resistance.

[0064] The spunbonded nonwoven fabric can be produced using a known spunbonded nonwoven fabric molding machine. More specifically, the spunbonded nonwoven fabric can be produced, for example, by melting a raw material polypropylene resin using an extruder, discharging the molten composition from a plurality of spinnerets, and cooling and stretching the fibrous resin as necessary, and then depositing it on a collecting surface and subjecting it to a heating and pressurizing treatment using an embossing roll.

[0065] The meltblown nonwoven fabric can be produced by using a known meltblown nonwoven fabric molding machine. More specifically, the meltblown nonwoven fabric can be produced by, for example, melting a polypropylene resin as a raw material, discharging it from a spinning nozzle, and pulling it with high-temperature, high-pressure gas to produce polypropylene meltblown fibers, which are then collected and deposited on a collector such as a perforated belt or perforated drum.

[0066] The sealed portion 4 may be formed by thermocompression or ultrasonic sealing. The sealed portion 4 may be formed continuously or discontinuously around the peripheral edge of the skin materials 3, 3 so as to surround the padding 2. When the sealed portion 4 is formed discontinuously, it is preferable that a plurality of parallel sealed portions 4 are formed so that a discontinuous portion of one sealed portion 4 is complemented by a continuous portion of another sealed portion 4.

[0067] The water pressure resistance of the seal portion 4 is not particularly limited as long as the effects of the present invention are achieved, but from the viewpoint of further suppressing water intrusion, it is preferably 100 mmH2O or more, more preferably 150 mmH2O or more, even more preferably 200 mmH2O or more, particularly preferably 250 mmH2O or more, and most preferably 300 mmH2O or more. The upper limit of the water pressure resistance of the seal portion 4 is not particularly limited, but can be, for example, 2000 mmH2O or less, 1000 mmH2O or less, or 500 mmH2O or less.

[0068] The sealing conditions are not particularly limited, but in the case of ultrasonic sealing, they can be arbitrarily adjusted by the pressure during sealing, output voltage, sealing time, sealing pattern, etc. If the seal is too strong, the water pressure resistance tends to decrease, so by appropriately adjusting the above factors, it is possible to maintain the water pressure resistance at a good level.

[0069] The width of the sealed portion 4 is not particularly limited, but is preferably in the range of 0.1 to 5.0 mm from the viewpoint of further improving the water pressure resistance of the sealed portion and suppressing breakage. The width of the sealed portion 4 can be, for example, 0.3 mm.

[0070] <Sound absorbing panel> Next, one embodiment of the sound absorbing panel of the present invention will be described with reference to FIG. 3, the sound-absorbing panel 11 of this embodiment includes a sound-absorbing material 1 and a frame 14 that houses the sound-absorbing material 1. The frame 14 is a box-shaped body that includes a rectangular shielding plate 12 that forms the bottom and side walls 13 that rise from the four sides of the shielding plate 12 and has an open end at the top, and includes a protection panel 15 that is placed at the open end of the frame 14 when the sound-absorbing material 1 is housed in the frame 14, and a support part 16 that is placed on the back 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.

[0071] 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 made of metal or resin. As the metal, a lightweight metal such as aluminum or stainless steel is preferably used.

[0072] It is preferable that the protective panel 15 protects the sound absorbing material 1 from solid objects such as hail, sleet, and pebbles while facilitating the penetration of sound waves. For this reason, in this embodiment, a punched plate having a large number of through holes 15a arranged on the surface is preferably used as the protective panel 15, but the protective 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%.

[0073] 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 sound wave penetration, weather, moisture, etc., and can be made of metal or resin. As the metal, a lightweight metal such as aluminum or stainless steel is preferably used.

[0074] <Method of manufacturing sound absorbing material> Next, a method for producing the railway sound-absorbing material of the present invention will be described. The method for producing a railway sound-absorbing material of the present invention includes a compression step of compressing polyethylene terephthalate containers that have been discarded and collected from railway-related businesses.

[0075] The railway-related establishments include railway stations, railway carriages, station buildings, hotels, logistics facilities, department stores, supermarkets, and convenience stores.

[0076] The compressed product of the polyethylene terephthalate container obtained in the compression step may be subjected to a metal detection step to remove metal from the compressed product. Thereafter, the polyolefin or polystyrene label attached to the polyethylene terephthalate container may be peeled off from the compressed product from which the metal has been removed. The polyethylene terephthalate container colored with a different resin may be removed from the compressed product from which the label has been peeled off by a sorting machine and / or manual force.

[0077] The method for producing a railway sound-absorbing material of the present invention includes a crushing step of crushing the compressed product obtained in the compression step. The compressed polyethylene terephthalate container is crushed together with a polyolefin cap in the crushing step and processed into flakes. Label fragments and powder in the flakes may be removed by a gravity separator. The flakes from which the label fragments and powder have been removed may be transferred to a water tank and separated based on the difference in specific gravity between the flakes and the caps. The separated flakes may be washed with an alkaline aqueous solution and dried. Colored flakes and powder may be removed from the dried flakes by a flake separator, and then metals may be detected and removed by a metal detector.

[0078] The method for producing a sound-absorbing material for railways of the present invention includes a fiberization step of fiberizing the recycled polyethylene terephthalate flakes obtained in the pulverization step. The recycled polyethylene terephthalate flakes are melted and fiberized by a conventional method.

[0079] The recycled polyethylene terephthalate fiber obtained in the fiberization step contains at least one impurity selected from the group consisting of polyolefin derived from the label and cap, polystyrene derived from the label, and polyvinyl chloride derived from the polyvinyl chloride container recovered together with the polyethylene terephthalate container, and the content of the impurity in the recycled polyethylene terephthalate fiber is in the range of 0.0005 to 0.5 mass%. The content falls within the range in the compression step and the pulverization step. When the content of the impurity in the polyethylene terephthalate composition subjected to the fiberization step is outside the range, at least one other component selected from the group consisting of polyolefin, polystyrene, polyvinyl chloride, virgin polyethylene terephthalate, and other recycled polyethylene terephthalate may be added to the polyethylene terephthalate flakes in the fiberization step so that the content falls within the range. Preferably, 20 to 100% by mass of the polyethylene terephthalate flakes are mixed with 80 to 0% by mass of the other components, more preferably, 30 to 100% by mass of the polyethylene terephthalate flakes are mixed with 70 to 0% by mass of the other components, and even more preferably, 50 to 100% by mass of the polyethylene terephthalate flakes are mixed with 50 to 0% by mass of the other components.

[0080] Examples of methods for fusing the ends of the sound-absorbing material 1 include a method in which a heat source such as an iron is applied to heat the ends to melt the resin and then pressure-bond the ends, an ultrasonic sealing method in which ultrasonic waves are applied to melt the resin while pressure-bonding the ends, a laser welding method, a vibration welding method, a high-frequency welding method, and a hot plate welding method. Of these, it is preferable to use the ultrasonic sealing method for fusing the ends.

[0081] The fusion temperature is not particularly limited as long as it is a temperature at which the resin of the skin material 3 can be fused, but from the viewpoint of further improving the water pressure resistance and suppressing peeling of the fused portion, it is preferably in the range of 130 to 160°C, and more preferably in the range of 140 to 155°C.

[0082] When the fusion step is performed by an ultrasonic sealing method, the output of the ultrasonic sealing device is not particularly limited as long as it can fuse the resin of the skin material 3, but from the viewpoint of further improving the water pressure resistance and suppressing peeling of the fused portion (sealed portion 4), it is preferably in the range of 1 to 5 V. Furthermore, the pressure in the pressure bonding is not particularly limited as long as it can fuse the resin of the skin material 3, but from the viewpoint of further improving the water pressure resistance and suppressing peeling of the fused portion, it is preferably in the range of 0.1 to 5 MPa. Furthermore, the speed at which the fused portion is formed is preferably 1 to 30 m / min from the viewpoint of improving the working efficiency while suppressing peeling of the fused portion. [Explanation of symbols]

[0083] 1 sound absorbing material, 2 padding, 3 skin material, 4 seal portion, 11 sound absorbing panel, 12 shielding plate, 13 side wall, 14 frame, 15 protective panel, 16 support.

Claims

1. A sound-absorbing material for railways, comprising a padding and a skin material containing the padding, The filling is a nonwoven fabric containing polyethylene terephthalate fibers, the polyethylene terephthalate fiber contains at least one impurity selected from the group consisting of polyolefin, polystyrene, and polyvinyl chloride, and the content of the impurity in the polyethylene terephthalate fiber is in the range of 0.0005 to 0.5 mass %; The polyethylene terephthalate fibers have an average fiber diameter in the range of 1.0 to 30 dtex.

2. 2. The railway sound-absorbing material according to claim 1, wherein the polyolefin comprises at least one selected from the group consisting of polyethylene and polypropylene.

3. 2. The railway sound-absorbing material according to claim 1, wherein the skin material is a skin material including a first spunbond nonwoven fabric, a meltblown nonwoven fabric adjacent to the first spunbond nonwoven fabric, and a second spunbond nonwoven fabric adjacent to the meltblown nonwoven fabric, or the skin material is a skin material including 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.

4. 4. The railway sound-absorbing material according to claim 3, wherein at least one selected from the group consisting of the first spunbond nonwoven fabric, the second spunbond nonwoven fabric, and the third spunbond nonwoven fabric contains fibers having an average fiber diameter in the range of 25 to 50 μm.

5. The railway sound-absorbing material according to claim 3, wherein the meltblown nonwoven fabric contains fibers having an average fiber diameter in the range of 0.5 to 5 μm.

6. The railway sound-absorbing material according to claim 3, wherein at least one selected from the group consisting of the first spunbond nonwoven fabric, the second spunbond nonwoven fabric, and the third spunbond nonwoven fabric contains hollow fibers.

7. A railway sound-absorbing panel comprising the railway sound-absorbing material according to any one of claims 1 to 6 and a frame for housing the railway sound-absorbing material.

8. A method for producing the railway sound-absorbing material according to any one of claims 1 to 6, comprising the steps of: A compression process for compressing polyethylene terephthalate containers discharged and collected from railway-related businesses; A crushing step of crushing the compressed product obtained in the compressing step; and The method includes a fiberization step of fiberizing the recycled polyethylene terephthalate flakes obtained in the pulverization step, The recycled polyethylene terephthalate fiber obtained in the fiberization step contains at least one impurity selected from the group consisting of polyolefins, polystyrene, and polyvinyl chloride, and the content of the impurity in the recycled polyethylene terephthalate fiber is in the range of 0.0005 to 0.5 mass %, The method for producing a sound-absorbing material for railways, wherein the average fiber diameter of the recycled polyethylene terephthalate fiber is in the range of 1.0 to 30 dtex.

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