JP5320002B2 - Storage structure for composite sound absorbing structure and composite sound absorbing structure disposed in the storage structure - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a compound sound absorbing structure improving sound absorbing performance by compounding a surface layer and a main material layer, and by combining them with nonwoven fabric in which a porous sound absorbing material is used as a base, and also to provide a storage structure using the same. <P>SOLUTION: The compound sound absorbing structure 10 is constituted by combining a base structure 1 obtained by compounding the surface layer 3 in which two nonwoven fabrics A and B being cloth materials such as span bond are used and the main material 2 which is composed of a polyester fabric or is mainly composed of the polyester fabric, with the nonwoven fabric 4 on which fire proofing/water proofing treatment is applied, a mesh structure 5 of a metallic system such as a metal mesh, and a punching metal 6 as a protective cover. By controlling flow resistance on the surface layer 3, it is effective for sound absorbing performance to adjust the flow resistance of the base structure 1 to be (2.0 to 5)&times;10<SP>4</SP>(N sec)/m<SP>4</SP>, and it is lightweight with a thickness of 40 to 50 mm, and it is also used as an all-weather type. The stable sound absorbing performance is provided from a low/middle frequency band to a high frequency band, especially around 400 Hz. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

The present invention relates to a composite sound absorbing structure disposed in the housing structure and the stowing structure is that double if the sound absorbing structure using the transportation railway.

  Conventionally, various materials and structures have been proposed as a sound-absorbing material used outdoors. Among them, a fiber-based sound-absorbing material is most commonly used as a base material that becomes a core. As a fiber-based sound absorbing material, glass wool is one of the most popular ones for a long time, and is used as an all-weather sound absorbing material for soundproof walls such as railways and roads.

  However, glass wool needs to be wrapped with a thin film or glass cloth to prevent scattering and protect the surface, and has problems in terms of work environment and long-term durability during the manufacturing process. Recently, as an alternative, polyester fiber-based sound absorbing materials are increasingly used from the viewpoints of environmental problems, recycling, sound absorption performance, work environment preservation and long-term durability. This polyester fiber-based sound absorbing material is usually treated with a non-woven fabric made of polyester fiber with a hot melt material and heat-bonded to the base material to adjust water repellency, durability and sound absorption characteristics. Is used on the sound incident side.

  In this case, it is common to adjust the overall flow resistance of the base material layer and the skin layer to produce sound absorption characteristics, but at present the sound absorption performance is not necessarily optimized, and there is a certain limitation There was a limit in trying to obtain higher sound absorption performance within the specified thickness.

  In general, porous materials such as glass wool and polyester fibers exhibit sound absorption characteristics when sound waves incident from the surface of the porous material travel through a three-dimensionally formed gap between the fibers. When the air existing in the gap vibrates, viscous resistance is generated, and incident acoustic energy is consumed as thermal energy. As a result, reflected acoustic energy is suppressed as a main sound absorbing mechanism. It is closely related to flow resistance, and the key to development is how to adjust the appropriate flow resistance so that high sound absorption performance can be obtained in the targeted frequency band. If the flow resistance is too small, the air moves easily, and if the flow resistance is too large, the air becomes difficult to move, the conversion efficiency from incident acoustic energy to thermal energy decreases, and high sound absorption performance cannot be obtained. At present, the sound absorption performance has not been optimized yet, and it can be said that the possibility of development of a new structure is still sufficient. In addition, although not a main factor, it is considered that friction between constituent fibers and internal attenuation of the fiber itself contribute to the conversion to thermal energy.

The flow resistance is defined by the following equation from the speed when a small air flow V flows in the direction perpendicular to the surface of the material and the pressure difference between both surfaces of the material.
R = ΔP / (V · d)
R: Flow resistance [N · sec / m ⁴ ]
ΔP: Pressure difference between both sides of the material
V: air flow rate per unit area [m ³ / (m ² / sec)]
d: Material thickness (m)
As shown in FIG. 9, the unit area flow resistance is measured by inserting a sound absorbing material with a diameter of 30 mm and a thickness of 30 mm into a metal pipe with a diameter of 29 mm, and Kate-Tech KES-F8-API air permeability tester ( It can be measured at a flow rate of 4 × 10 ⁻² m / sec).

  The flow resistance when the surface layer and the base material layer are combined determines the sound absorption rate of the sound absorbing material. The flow resistance is changed by: a: changing the density of the porous material as the base material layer, b: porous By changing the diameter and blending ratio of the fibers that make up the porous material, c: changing the properties of the fibers that make up the porous material, d: changing the properties and specifications of the non-woven fabric (for example, spunbond) of the skin layer, etc. Although it can be controlled, it cannot be said that it has been optimized by the prior art.

The present invention has been made in view of the prior art as described above, and its purpose is to combine a skin layer and a base material layer, and combine a nonwoven fabric based on a porous sound absorbing material, and at around 400 Hz. It is intended to provide a storage structure for a composite structure sound absorber that can be used as an all-weather type, and a composite sound absorption structure disposed in the storage structure .

  In the field of application, the use of polyester fiber-based sound absorbing materials is expanding in fields such as railway vehicles, railway and road noise barriers, construction machinery, etc., and the sound absorption with good space factor is minimized. There is an increasing demand for sound-absorbing materials with excellent characteristics.

In the present invention, focusing on the flow resistance of the skin layer, and controlling the flow resistance, the flow resistance of the composite structure of the skin layer and the base material is (2.0 to 5) × 10 ⁴ N · It has been found that adjusting to sec / m ⁴ is very effective. Based on this knowledge, the composite sound-absorbing structure according to the present invention uses two non-woven fabrics for the skin layer, devised a method of compounding with polyester fibers or a base material mainly composed thereof, and further, punching metal, metal It is composed of a combination of a network structure and a non-woven fabric, provides a sound absorption performance that is stable from the middle to low frequency band to the high frequency band, and provides a highly practical means that can meet the above needs.

The composite sound-absorbing structure according to the present invention is composed of a skin layer composed of two cloth-like materials such as nonwoven fabric (spunbond) and a polyester fiber or a base material layer mainly composed of it, and has a thickness of 40 to 50 mm. Based on a porous sound-absorbing material with a greatly improved sound absorption rate in a wide frequency range from mid to low range to a wide band, and a metal network structure, flame retardant treatment and water repellent treatment By combining these non-woven fabrics, the sound absorbing performance near 400 Hz is further improved, and the composite structure sound absorbing body that can be used as an all-weather type is provided.
Note that it is effective to insert a film between the surface layer and the base material layer in order to enhance the sound absorption performance in the low sound range even if the sound absorption performance in the sound absorption structure of the present invention is somewhat sacrificed. It is a structure that can be dealt with in the invention.

  According to the composite sound-absorbing structure according to the present invention, a sound-absorbing material having excellent sound-absorbing characteristics with a small space factor and a good space factor can be obtained in outdoor fields such as railway vehicles, railway and road noise barriers, and construction machinery. Moreover, from the mid-low frequency band to the high frequency band, especially in the vicinity of 400 Hz, the sound absorption rate is increased, the sound absorption performance is further stabilized and improved, light weight, high practicality, and a composite structure that can be used as an all-weather type A sound absorber can be obtained.

  Further, according to the housing structure for the composite sound absorbing structure according to the present invention, the sound absorbing structure is disposed in a substantially sealed housing other than the sound wave incident surface, and the surface substantially orthogonal to the sound wave incident surface of the housing Therefore, the sound absorption characteristics in the mid-low range can be further improved without reducing the sound absorption performance in the high range.

An embodiment of a composite sound absorbing structure according to the present invention is schematically shown in FIG. 1A is a sectional view, and FIG. 1B is a perspective view. As shown in FIG. 1, a base structure 1 of a composite sound absorbing structure includes a base material 2 and a skin layer 3, and provides a method for optimally controlling the flow resistance of the skin layer 3. The base structure 1 of the composite sound absorbing structure is formed on a base material 2 made of a polymer porous material having a flow resistance of (1.5 to 3.5) × 10 ⁴ N · sec / m ^4. The skin layer 3 composed of the two non-woven fabrics A and B is superposed and combined. The base structure 1 is, for example, a powder or spider web (network) on the back surface of a single nonwoven fabric A (equivalent single fiber diameter of 11 to 25 μm, surface density of 60 to 130 g / m ² ) used for the skin layer 3. A hot melt material such as is applied or transferred in advance and superimposed on the base material 2 and heated and pressurized to form an integral composite with the base material 2, and another nonwoven fabric B (with an equivalent single fiber diameter of 11 to 25 μm and the surface density is 60 to 130 g / m ² ). The base structure 1 has a flow resistance of (2.0 to 5.0) × 10 ⁴ N · sec / m ⁴ as a composite.

  FIG. 2 is a view schematically showing a sound absorbing structure according to the present invention. FIG. 2 (a) is a cross-sectional view showing an example of the sound absorbing structure according to the present invention, and FIG. 2 (b) is a base structure of the sound absorbing structure. It is sectional drawing. As shown in FIG. 2A, on the base structure 1, a non-woven fabric 4 having improved practical performance such as flame retardancy and water repellency, and a # 100 metallic mesh 5 forming a metal network structure are stacked. Thus, the sound absorbing structure 10 is improved in practicality. These non-woven fabrics 4 and metallic meshes 5 have a small opening diameter and a high flow resistance, so that there is a possibility that the flow resistance may increase remarkably due to fine dust due to long-term outdoor use, clogging due to repainting, etc. The open area ratio is made larger than that of the nonwoven fabrics A and B constituting the structure 1 to reduce the flow resistance. By configuring in this way, it is possible to prevent deterioration of the sound absorption rate due to secular change in the composite sound absorption structure 10.

  In actual application, an air gap 7 of about 2 to 10 mm is provided under a protective cover such as a punching metal (opening ratio 20% or more) 6 having a lower flow resistance, and the punching metal 6 becomes the sound incident side. Thus, the composite sound absorbing structure 10 is often installed. Further, as shown in FIG. 2B, the non-woven fabric A may be subjected to the same hot-melt treatment as the non-woven fabric B, and the non-woven fabric B and the base material may be overlapped, heated and pressurized to be integrated into an integral composite. The specifications of the nonwoven fabric A and the nonwoven fabric B may be the same or different.

  FIG. 3 shows a state where the porous sound absorbing material (base material 2) is attached to the rigid wall surface. When sound waves are incident from the left side (skin side) of FIG. 3, the velocity of air particles is 0 on the rigid wall surface, and from the rigid wall surface. It becomes maximum at a position c / 4f (c: speed of sound in air [cm / sec], f: frequency of incident sound wave [Hz]) on the left. In the 400-2000 Hz band, which is likely to be a problem due to railway and road noise, the velocity of air particles is maximum at 40 mm or more, so it is better to adjust the flow resistance with the skin layer 3 until the thickness is about 50 mm. The viscous resistance increases the efficiency of conversion from acoustic reflection energy to thermal energy, and can efficiently improve the sound absorption performance.

[Point 1] As the best mode of the all-weather sound absorbing structure according to the present invention, punched metal, voids, metal network structure, spunbond nonwoven fabric imparted with flame retardancy and water repellency, two spunbond nonwoven fabrics and polyester It is a combination of composites using a fiber-based nonwoven fabric as a base material. The most important point of the present invention is that the flow resistance of the entire structure is made of two spunbonded nonwoven fabrics laminated on the surface of the base material, and in particular, (2.0 to 5.0 ) × 10 ⁴ N · sec / m ⁴ . If adjusted so that it can be accommodated, a wide range of sound absorption performance can be realized from the mid-low frequency band to the high frequency band, and it is possible to realize a light-weight and compact all-weather sound absorption structure that is highly practical.

  [Point 2] The base structure, which is the core of the present invention consisting of two spunbond nonwoven fabrics and a base material in Point 1, is a structure in which each is heat-fused and integrated with a powder-like or web-like hot-melt material. It is also possible to have a structure in which one spunbond nonwoven fabric and the base material are fused and integrated with a hot melt material, and then another spunbond nonwoven fabric is stacked on top of each other without bonding. good.

  [Point 3] By using two types of spunbond nonwoven fabrics at point 2 having different specifications, the flow resistance can be easily adjusted.

  [Point 4] A flame-retardant and water-repellent spunbond nonwoven fabric that constitutes the present invention, and two spunbond nonwoven fabrics with a base structure and a base material are all combined in a polyester fiber system to create a recyclable earth. A gentle all-weather composite sound absorbing structure can be provided.

  [Point 5] When particularly high flame retardancy is not required, there may be no spunbonded nonwoven fabric between the base structure and the metal network structure.

  [Point 6] Regarding the punching metal of the protective cover, the back side of the so-called punching metal is placed on the front side of the sound absorbing structure, that is, the acoustic wave so that the punching direction of the opening at the time of punching metal manufacture and the incident direction of the sound wave are reversed. The incident side should be used. This is because the punching hole has a smaller diameter in the punching direction due to deformation during processing, so that the surface of the punching surface has a smaller area of the metal portion than the back surface. For this reason, when a part of the punching metal is heated due to a fire flame or the like, the back surface having a smaller metal part area has a larger spreading force, and as a result, the back surface on the side where the diameter of the punching hole is small is convex. It transforms to become. Therefore, the punching metal and the sound absorbing structure are deformed in a direction in which the gap becomes large. Thereby, the fireproof performance of the composite sound absorbing structure can be improved.

FIG. 4 is a graph showing a change in sound absorption rate with respect to frequency when a spunbond nonwoven fabric is added to the sound absorption structure. The samples B, BC, and BS shown in FIG. 4 are as follows.
Sample B: Sound-absorbing structure in which a spunbonded nonwoven fabric (polyester fiber: surface density 100 g / m ² ) and a base material (thickness 35 mm) having a flow resistance of 1.0 × 10 ⁴ N · sec / m ⁴ are integrally combined body. Flow resistance 1.5 × 10 ⁴ N · sec / m ⁴
Sample BC: A composite sound-absorbing structure in which the same spunbonded nonwoven fabric as the skin layer is inserted in the center of the base material of sample B. Flow resistance 2.0 × 10 ⁴ N · sec / m ⁴
Sample BS: A composite sound-absorbing structure in which the same spunbond nonwoven fabric as that of the skin is inserted between the skin layer and the base material of Sample B and two layers are stacked. Flow resistance 2.2 × 10 ⁴ N · sec / m ⁴
As base over scan structure, the conventional structure in which Supanbo down de nonwoven piece and the base material and the composite was sound absorbing structure (Sample B) even more, the sound absorbing performance in a low frequency band of the sound absorbing performance is improved (high-frequency band While maintaining the flow resistance of the composite sound-absorbing structure, the spunbonded nonwoven fabric (same as the skin layer of sample B) is placed in the middle of the base material even with almost the same flow resistance as shown in FIG. It is more effective to insert between the skin layer and the base material and increase the flow resistance of the skin layer (sample BS) than the one with the same hot melt treatment on the back surface (sample BC). It shows that there is.
This proves what was proposed in FIG. 3 and also shows the effectiveness of the present invention. Moreover, if it is the same sound absorption performance by this, it can be thinner than the conventional structure, and it is effective also in practical use, such as weight reduction, economical efficiency, and space saving.

FIG. 5A shows an example of a conventional sound absorbing structure (sample M: a composite sound absorbing structure having a base structure as a conventional structure), and FIG. 5B shows an example of a sound absorbing structure of the present invention (sample N: a base structure). The composite sound absorbing structure having the structure of the present invention is shown, and the sound absorbing performance (normal incidence method sound absorption rate) is as shown in the graph of FIG. This is a significant improvement over the product and demonstrates the superiority of the present invention.
[specification]
・ Punching metal: Hole diameter 2mm, Pitch 3.5mm, Staggered arrangement Opening rate 30%
Metal network structure: Stainless steel (mesh: # 100)-Combustion resistance, coating resistance-Spunbond nonwoven fabric: Polyester fiber, high flame retardancy, water repellency, close contact-80 g / m ²
-Base structure-Spunbond nonwoven fabric: Polyester fiber (fiber shape - circular), surface density-100 g / m ²
Spunbond nonwoven fabric: polyester fiber (fiber shape-ellipse), surface density-90 g / m ²
Base material: polyester fiber thickness 40 mm, surface density −1800 g / m ²
[Flow resistance]
Sample M: 1.7 × 10 ⁴ N · sec / m ⁴
Sample N: 2.5 × 10 ⁴ N · sec / m ⁴

FIG. 7 (a) shows an example of the storage structure 20 in which the gap 11 is provided around the composite sound absorbing structure 10 of the present invention (the size of the storage structure is 1170 mm × 470 mm, the gap width is 30 mm), and FIG. 7 (b) shows the storage structure. A storage structure 20 a in which a gap 11 of the structure 20 is filled with a liner 12 is shown. FIG. 8 shows the results of measuring the sound absorption rate by the reverberation chamber method for the storage structure shown in FIG. By providing the gap 11, a kind of Helmholtz resonator is constituted by the space between the sound absorbing structure 10 and the gap 11 of the storage structure 20 and the thin gap communicating with the outside, and the sound absorption rate of the sound absorbing structure 10 is maximized. It can be seen that the sound absorption rate of the storage structure 20 is further increased in the frequency band.

The present invention provides an all-weather type sound absorbing structure having a relatively thin thickness and high sound absorption performance in a wide band as compared with a conventional porous sound absorbing material or a resonator type structural sound absorbing body. since the can, weight reduction, economic efficiency, is the advantage in terms of, such as Lisa Lee cycle resistance, because the high versatility, construction machinery, agricultural machinery, industrial and vehicle areas such as railway vehicles, railway, road, such as civil engineering fields, such as construction work Can be used in a wide range of fields.

The figure which shows the base structure of the composite sound-absorbing structure by this invention. The figure which shows an example of the composite sound absorption structure by this invention. The figure explaining the sound absorption principle in a composite sound absorption structure. The graph which shows an example of the sound absorption characteristic of the composite sound absorption structure by this invention. Sectional drawing of the composite sound-absorbing structure by this invention, and the conventional composite sound-absorbing structure. The graph which shows an example of the sound absorption characteristic of the composite sound absorption structure shown in FIG. Sectional drawing which shows an example of the storage structure using the composite sound-absorbing structure by this invention. The graph which shows an example of the sound absorption characteristic of the storage structure shown in FIG. The schematic diagram which shows the measuring method of flow resistance.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Base structure 2 Base material 3 Skin layer A, B Non-woven fabric 4 Non-woven fabric which improved flame retardance 5 Metal mesh (metal network structure) 6 Punching metal (protective cover)
7 Gap 10 Composite sound absorbing structure 11 Gap 12 Liner 20 Storage structure (with gap)
20a Storage structure (no gap. Liner filled)

Claims (8)

From the incident surface of the sound wave, the protective cover, the mesh structure in which one or more cloth-like or mesh materials are in close contact, the cloth-like structure in which one or more cloth-like materials are in close contact, and the porous base material are A composite sound-absorbing structure that is arranged in order in the incident direction and in which the air flow resistance increases in the order of the protective cover, the mesh structure, and the cloth-like structure is contained in a container that is substantially sealed except for the incident surface of the sound wave. And a gap formed around the composite sound absorbing structure is provided between a surface substantially orthogonal to a sound wave incident surface of the storage body and the composite sound absorbing structure. Storage structure for composite sound absorbing structure. A composite sound absorbing structure disposed in the housing structure of claim 1,
The cloth-like structure is formed by fusing or closely adhering at least two layers of the cloth-like material, and the cloth-like structure is adhered or fused to the porous base material. . A composite sound absorbing structure disposed in the housing structure of claim 1,
At least one of the materials constituting the mesh structure is a metallic mesh or a cloth-like material subjected to a flame retardant treatment. In the composite sound-absorbing structure according to claim 2 or 3 ,
The porous base material is a polymer fiber-based porous material having a flow resistance of (1.5 to 3.5) × 10 ⁴ N · sec / m ⁴ , and the cloth-like structure is powdery on the back surface. Or, it is a structure in which a nonwoven fabric obtained by applying or transferring a hot melt material such as a web of nests (network shape) in advance is doubled, and the cloth-like structure and the porous base material are heated and pressurized together. The base structure is formed by heat fusion integrated composite, and further, the flow resistance as a composite in which the network structure is stacked thereon is (2.0 to 5.0) × 10 ⁴ N. · sec was adjusted to / m ^4, characterized in that arranged structures having punching metal or aperture as the protective cover at a space in front of the structural network of that the incident side of the sound composite Sound absorbing structure. In the composite sound-absorbing structure according to claim 4,
The porous base material has a nonwoven fabric on which a hot melt material such as a powder or a web of web (network shape) is applied or transferred in advance on the back surface, and is heated and pressed to form a heat fusion integrated composite. A base structure formed by simply laminating another non-woven fabric is formed, and a network structure in which a non-woven fabric and a mesh material are adhered to each other is further superimposed thereon, and the flow resistance as this composite is (2 0.0 to 5.0) × 10 ⁴ N · sec / m ⁴ . In the composite sound-absorbing structure according to claim 3,
The composite sound absorbing structure according to claim 1, wherein the metallic mesh is made of a metal such as SUS or aluminum and has meshes # 40 to 150. In the composite sound absorbing structure disposed in the storage structure according to claim 1,
The composite sound absorbing structure according to claim 1, wherein the protective cover is made of a metal such as SUS or aluminum, and small openings are dispersed on the surface so that the opening ratio is 20% or more. In the composite sound absorbing structure disposed in the storage structure according to claim 1,
The protective cover is a punching metal, and a composite sound absorbing structure characterized in that a punching direction at the time of punching manufacture and an incident direction of a sound wave to the protective cover are opposite to each other.

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