Sound absorbing panel

Abstract

To provide a sound absorbing panel having excellent sound absorbing performance.SOLUTION: A sound absorbing panel 1 comprises a front plate 23 having a through hole h and disposed on a sound source side, a sound absorbing material 3, an air layer 4, and a sound insulating plate 24 in this order, wherein the sound absorbing material 3 comprises a protective layer 33, a base material layer 31, and a resistance layer 32 in this order from the sound source side, and the base material layer 31 is an air permeable material and has a flow resistance 5kPa sec / m2 or less, the protective layer 33 is an air-permeable material and has a flow resistance of 1 MPa sec / m2 or more, and the resistance layer 32 is the air-permeable material and the flow resistance of the resistance layer 32 is 0.9-2 times that of the protective layer 33. Thus, even if a relatively lightweight material is used for the base material layer 31, an excellent sound absorption effect can be obtained.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a sound absorbing panel that absorbs noise generated by vehicles such as trains and automobiles. [Background technology]

[0002] 2. Description of the Related Art In order to suppress noise caused by running vehicles, a method of installing sound-absorbing panels along roadways and railroad tracks has been commonly used, and various configurations of the sound-absorbing panels used have been proposed.

[0003] For example, in Patent Document 1, the applicant has proposed a thin soundproof panel in which a sound-absorbing material is installed inside a hollow body formed by a front portion having multiple openings and a rear portion having sound-insulating properties, the sound-absorbing material being made of organic plastic fiber material and having a thickness dimension of 18 to 45 mm, and further, a rear air space having a depth dimension of 5 to 40 mm is formed between the rear portion and the sound-absorbing material, and the thickness dimension of the hollow body is 25 to 60 mm. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2001-193021 A Summary of the Invention [Problem to be solved by the invention]

[0005] The thin soundproof panel shown in Patent Document 1 has a good sound absorbing performance by providing a back air layer between the sound absorbing material and the back part having sound insulation properties, but the present invention provides a sound absorbing panel with even better sound absorbing performance. Normally, the higher the surface density of the sound absorbing material, the better the sound absorbing performance, but the weight is heavier accordingly, which causes problems such as a heavy load during transportation of the soundproof panel and construction on site. [Means for solving the problem]

[0006] In order to solve the above problems, the inventors of the present invention have conducted extensive research into the structure of sound-absorbing materials. As a result, they have found that by arranging a protective layer and a resistance layer having a predetermined air permeability on the front and back sides of the sound-absorbing material, even if the sound-absorbing material has a relatively low flow resistance, it can have high sound-absorbing performance, which led to the completion of the present invention.

[0007] That is, the sound-absorbing panel according to the present invention is a sound-absorbing panel having, in this order, a front panel having a through hole and arranged on the sound source side, a sound-absorbing material, an air layer, and a sound-insulating plate, The sound-absorbing material has a protective layer, a sound-absorbing layer, and a resistance layer in this order from the sound source side, The sound absorbing layer has a flow resistance of 5 kPa·sec / m 2 Below is The protective layer has a flow resistance of 1MPa·sec / m 2 That's all. The flow resistance of the resistance layer is 0.9 to 2 times that of the protective layer.

[0008] In the present invention, the air flow resistance of the resistance layer is 1 or more, or the flow resistance of the resistance layer is 2 MPa sec / m 2 More preferably, it is equal to or greater than this.

[0009] In the present invention, the airflow resistance and flow resistance of the resistance layer are preferably 0.9 to 1.1 times the airflow resistance and flow resistance of the protective layer. Effect of the Invention

[0010] With the sound-absorbing panel of the present invention, even if a sound-absorbing layer with a relatively low flow resistance, i.e., a low specific gravity, is selected, excellent sound-absorbing performance is exhibited by arranging protective layers and resistive layers that provide a predetermined flow resistance in front of and behind the sound-absorbing layer. [Brief description of the drawings]

[0011] [Figure 1]1A and 1B show an embodiment of a sound-absorbing panel according to the present invention, in which FIG. 1A is a plan view and FIG. [Diagram 2] FIG. 2 is a schematic cross-sectional view taken along line AA in FIG. [Diagram 3] 1 is a table showing the flow resistance of each member constituting each of the sound-absorbing panels of Examples 1 to 5 and Comparative Examples 1 to 5, and the sound absorption coefficient of the resulting sound-absorbing panels. [Figure 4] 1 is a table showing the flow resistance of each member constituting each of the sound-absorbing panels of Examples 6 to 10 and Comparisons 6 to 10, and the sound absorption coefficient of the resulting sound-absorbing panels. [Diagram 5] 1 is a table showing the flow resistance of each member constituting each of the sound-absorbing panels of Comparative Examples 11 to 18, and the sound absorption coefficient of the resulting sound-absorbing panels. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be specifically described with reference to the drawings. In the drawing, 1 is a sound-absorbing panel. The sound-absorbing panel 1 shown in FIG. 1 includes a main body 2 formed in the shape of a horizontally long rectangular box. The main body 2 includes a rectangular frame body F assembled from left and right vertical frames 21 and top and bottom horizontal frames 22, each of which is formed into an elongated body having a rectangular cross section. A front panel 23 and a sound-proof panel 24 are attached to the front and rear sides of the frame body F, respectively, so as to cover the openings in the areas surrounded by the vertical frames 21 and horizontal frames 22, thereby forming the hollow box-shaped main body 2.

[0013] The front plate 23 has a through hole h formed therein, which connects the inside and outside of the main body 2 . The through holes h are small circular holes penetrating the front plate 23, and a large number of them are formed at intervals over substantially the entire surface of the front plate 23. For the sake of simplicity, FIG. 1B shows the through holes h only at some of the four corners of the front plate 23, and FIG. 2 omits the through holes h.

[0014] Fig. 2 is a schematic cross-sectional view taken along line AA in Fig. 1. Inside the main body 2, a rectangular plate-shaped sound absorbing material 3 is housed. The sound-absorbing material 3 is shaped and sized so that its top, bottom, left and right ends are positioned near each of the horizontal frames 22 and each of the vertical frames 21, respectively, and is configured to efficiently absorb noise that enters the inside through the through hole h of the front panel 23. The sound absorbing material 3 is formed to have a thickness smaller than the distance between the front plate 23 and the sound insulating plate 24, and is disposed close to the front plate 23 and installed inside the main body 2. In other words, a gap serving as an air layer 4 is provided between the rear surface of the sound absorbing material 3 and the sound insulation plate 24 .

[0015] The sound absorbing material 3 includes a base layer 31 made of a breathable material. The breathable material forming the base material layer 31 may be any known material used as a sound absorbing material for the sound absorbing panel 1, such as a woven or nonwoven fabric made of a fibrous material, or a foam made of a synthetic resin. In addition, materials that can be used for the base layer 31 include polyester-based resins such as polyethylene terephthalate, polytrimethylene terephthalate, polybutylene terephthalate, polyhexamethylene terephthalate, polytetramethylene terephthalate, poly-1,4-dimethylcyclohexane terephthalate, and polyethylene naphthalate, polyolefin-based resins such as polyethylene and polypropylene, polyamide-based resins such as nylon and aramid fiber, synthetic resins such as acrylic resins, melamine resins, and polyurethane-based resins, rubber-based materials such as EPDM, wood-based materials such as rayon, cellulose nanofiber, and cotton, metals such as aluminum and stainless steel, and inorganic materials such as carbon fiber, glass wool, and rock wool. In addition, the above-mentioned materials may be used selectively or in combination. When a nonwoven fabric made of a fibrous material is used for the base material layer 31, it may be formed into a cloth-like sheet body or a cotton-like body.

[0016] The sound absorbing material 3 has a protective layer 33 disposed in front of a base layer 31 . Specifically, the protective layer 33 is arranged to cover the front surface of the base material layer 31, and prevents foreign matter such as rainwater or dust that enters the inside of the main body 2 through the through hole h from coming into contact with the base material layer 31 or the resistance layer 32 described later. That is, by providing the protective layer 33, deterioration of the sound absorbing material 3 caused by the foreign matter entering the main body 2 is prevented. The protective layer 33 can be formed using a known material that has better weather resistance than the base material layer 31 .

[0017] The sound absorbing material 3 is provided with a resistance layer 32 disposed behind a base layer 31 . The resistance layer 32 is made of a breathable material and is disposed so as to cover the rear surface of the base layer 31 . The breathable material forming the resistance layer 32 may be any known material, such as a woven or nonwoven fabric made of a fibrous material, or a foam made of a synthetic resin. The material of the resistance layer 32 may be polyester resins such as polyethylene terephthalate, polytrimethylene terephthalate, polybutylene terephthalate, polyhexamethylene terephthalate, polytetramethylene terephthalate, poly-1,4-dimethylcyclohexane terephthalate, and polyethylene naphthalate, polyolefin resins such as polyethylene and polypropylene, polyamide resins such as nylon and aramid fiber, acrylic resins, melamine resins, fluorine resins such as ETFE, and polyurethane resins, rubber materials such as EPDM, wood materials such as rayon, cellulose nanofiber, and cotton, metals such as aluminum and stainless steel, carbon fibers, and inorganic materials such as glass wool, glass cloth, and rock wool. The above-mentioned materials may be used selectively or in combination. When a nonwoven fabric made of a fibrous material is used for the resistance layer 32, it may be formed into a cloth-like sheet body or a cotton-like body.

[0018] By providing the resistance layer 32, the sound absorbing performance of the sound absorbing panel 1 is improved. Specifically, by providing the resistance layer 32, which is made of a material with greater flow resistance, behind the base layer 31, a portion of the noise that enters the sound-absorbing material 3 and passes through the base layer 31 is reflected by the resistance layer 32, and the phase difference generated in the reflected sound causes the incident sound and the reflected sound to cancel each other out, thereby improving the sound absorption performance.

[0019] When the base material layer 31 is the same size, the heavier the base material layer 31 is, and in the case of a breathable material as in this embodiment, the greater the flow resistance, the higher the soundproofing performance tends to be. However, when a protective layer 33 for protecting the base material layer 31 is provided on the surface of the base material layer 31, the soundproofing performance is affected. Normally, noise is reflected by the protective layer 33, and the sound absorbing performance of the sound absorbing material 3 decreases.

[0020] Here, it was discovered that by having a specific relationship between the flow resistance of the protective layer 33 and the resistance layer 32, which are placed on the front and back surfaces of the base layer 31, the sound absorption performance is relatively excellent even when the flow resistance of the base layer 31 is relatively small, and this led to the completion of the present invention.

[0021] An embodiment of the sound-absorbing material 3 of the sound-absorbing panel 1 according to the present invention and a comparative example will be described below.

[0022] Example 1 Spunbond nonwoven fabric made of polyester resin fibers (thickness 0.45 mm, basis weight 165 g / m 2 ), a protective layer 33 made of a cotton-like PET fiber nonwoven fabric made of polyethylene terephthalate resin fiber (thickness 40 mm, density 22 kg / m 3 ), and a spunbond nonwoven fabric (thickness 0.45 mm, basis weight 165 g / m) made of polyester-based resin fiber. 2 ) was attached to provide a resistance layer 32, thereby forming the sound-absorbing material 3 of Example 1.

[0023] [Flow resistance measurement] A method for measuring the flow resistance of each member constituting the sound-absorbing material 3 of Example 1 will be described. First, a member constituting the base layer 31 of the sound-absorbing material 3 was cut into a circle having a diameter of 90 mm to prepare a measurement sample. Moreover, each of the members constituting the protective layer 33 and the resistive layer 32 of the sound absorbing material 3 was cut into a square of 100 mm in length and 100 mm in width to prepare a measurement sample. Next, the airflow resistance of each of the measurement samples was measured using an air permeability tester (manufactured by Kato Tech Co., Ltd., model: KES-F8-AP1). Finally, the measured airflow resistance was divided by the thickness of the measurement sample to calculate the flow resistance. The flow resistance of each component is shown in Figure 3.

[0024] [Measurement of normal incidence sound absorption coefficient] A method for measuring the normal incidence sound absorption coefficient in Example 1 will be described. [Measurement using a thin tube] First, for the sound-absorbing material 3 of Example 1, each member was cut into a circle having a diameter of 29 mm, and the protective layer 33, the base layer 31, and the resistance layer 32 were arranged in this order to form a measurement sample. Next, the normal incidence sound absorption coefficient of the measurement sample of Example 1 was measured based on JIS A 1405. Specifically, a normal incidence sound absorption coefficient measurement system 4206 type acoustic impedance tube (manufactured by Brüel & Kjær AG) and normal incidence sound absorption coefficient measurement software MS1021 (manufactured by Spectris Inc.) were used to measure the frequency range of 500 Hz to 6400 Hz at 2 Hz intervals, with the rear air layer 4 corresponding to air layer 4 set at 40 mm. [Measurement using a large pipe] For the sound-absorbing material 3 of Example 1, each member was cut into a circle having a diameter of 100 mm, and the protective layer 33, the base layer 31, and the resistance layer 32 were arranged in this order to form a measurement sample. Next, the normal incidence sound absorption coefficient of the measurement sample of Example 1 was measured based on JIS A 1405. As with the above measurement method, a normal incidence sound absorption coefficient measurement system 4206 type acoustic impedance tube (Brüel & Kjær AG) and normal incidence sound absorption coefficient measurement software MS1021 (Spectris Inc.) were used, and measurements were taken every 0.5 Hz in the frequency range of 50 Hz to 1600 Hz, with the rear air layer 4 corresponding to air layer 4 set at 40 mm. [Combined normal incidence sound absorption coefficient] Using the automatic synthesis function in the software, the normal incidence sound absorption coefficient measured on the above 29 mm diameter sample and the normal incidence sound absorption coefficient measured on the 100 mm diameter sample were synthesized to calculate the normal incidence sound absorption coefficient from 50 to 6400 Hz. The data is given in 0.5 Hz increments from 50 to 500 Hz, and in 2 Hz increments from 500 to 6400 Hz. Finally, the normal incidence sound absorption coefficient values ​​measured using the above method were simply averaged for the frequency ranges of 1600 Hz to 2000 Hz and 1000 Hz to 2000 Hz to calculate the average normal incidence sound absorption coefficient. The average normal incidence sound absorption coefficient of the sound-absorbing material 3 calculated by the above procedure is as shown in FIG.

[0025] Example 2 In comparison with Example 1, the protective layer 33 was a spunbond nonwoven fabric made of polyester resin fibers (thickness: 0.39 mm, basis weight: 125 g / m 2 ) was used as Example 2, and the flow resistance of each member was measured (measurements were omitted for members that had already been measured) and the normal incidence sound absorption coefficient was measured. The values ​​of flow resistance and average normal incidence sound absorption coefficient are shown in Figure 3.

[0026] Example 3 In comparison with Example 1, the resistance layer 32 was a spunbond nonwoven fabric made of polyester resin fibers (thickness: 0.67 mm, basis weight: 260 g / m 2 ) was used as Example 3, and the flow resistance of each member was measured (measurements were omitted for members that had already been measured) and the normal incidence sound absorption coefficient was measured. The values ​​of flow resistance and average normal incidence sound absorption coefficient are shown in Figure 3.

[0027] Example 4 In comparison with Example 1, the resistance layer 32 was a spunbond nonwoven fabric made of polyester resin fibers (thickness: 0.67 mm, basis weight: 260 g / m 2 ), and the protective layer 33 is a spunbond nonwoven fabric (thickness 0.39 mm, basis weight 125 g / m) made of polyester resin fiber. 2 ) was used as Example 3, and the flow resistance of each member was measured (measurements were omitted for members that had already been measured) and the normal incidence sound absorption coefficient was measured. The values ​​of flow resistance and average normal incidence sound absorption coefficient are shown in Figure 3.

[0028] Example 5 In comparison with Example 1, the resistance layer 32 was a spunbond nonwoven fabric made of polyester resin fibers (thickness: 0.39 mm, basis weight: 125 g / m 2 ), and the protective layer 33 is a spunbond nonwoven fabric (thickness 0.39 mm, basis weight 125 g / m) made of polyester resin fiber. 2 ) was used as Example 3, and the flow resistance of each member was measured (measurements were omitted for members that had already been measured) and the normal incidence sound absorption coefficient was measured. The values ​​of flow resistance and average normal incidence sound absorption coefficient are shown in Figure 3.

[0029] (Comparative Examples 1 to 5) In comparison with Examples 1 to 5, the base layer 31 was a cotton-like PET fiber nonwoven fabric (thickness 40 mm, density 40 kg / m 3 ) were measured for normal incidence sound absorption coefficient as Comparative Examples 1 to 5. The average normal incidence sound absorption coefficient values ​​are shown in FIG.

[0030] (Examples 6 to 10) In comparison with Examples 1 to 5, the thickness of the base material layer 31 was set to 40 mm, and the rear air layer 4 corresponding to the air layer 4 was set to 50 mm to form the air layer 4, which were designated as Examples 6 to 10, and the normal incidence sound absorption coefficient was measured. The average normal incidence sound absorption coefficient values ​​are shown in FIG.

[0031] (Comparative Examples 6 to 10) In comparison with Comparative Examples 1 to 5, the thickness of the base material layer 31 was set to 40 mm, and the rear air layer 4 corresponding to the air layer 4 was set to 50 mm to form the air layer 4, and the normal incidence sound absorption coefficient was measured for Comparative Examples 6 to 10. The average normal incidence sound absorption coefficient values ​​are shown in FIG.

[0032] Comparative Example 11 In comparison with Example 1, the resistance layer 32 was a spunbond nonwoven fabric made of polyester resin fibers (thickness: 0.39 mm, basis weight: 125 g / m 2 ) was used as Comparative Example 11, and the normal incidence sound absorption coefficient was measured. The average normal incidence sound absorption coefficient value is shown in FIG.

[0033] Comparative Example 12 In comparison with Example 1, the base layer 31 was a cotton-like PET fiber nonwoven fabric made of polyethylene terephthalate resin fiber (thickness 40 mm, density 40 kg / m 3 ), and the resistance layer 32 is a spunbond nonwoven fabric (thickness 0.39 mm, basis weight 125 g / m) made of polyester resin fiber. 2 ) and the normal incidence sound absorption coefficient was measured for this sample, which was designated Comparative Example 12. The average normal incidence sound absorption coefficient values ​​are shown in FIG.

[0034] Comparative Example 13 In comparison with Example 6, the resistance layer 32 was a spunbond nonwoven fabric made of polyester resin fibers (thickness: 0.39 mm, basis weight: 125 g / m 2 ) was used as Comparative Example 13, and the normal incidence sound absorption coefficient was measured. The average normal incidence sound absorption coefficient value is shown in FIG.

[0035] Comparative Example 14 In comparison with Example 6, the base layer 31 was a cotton-like PET fiber nonwoven fabric made of polyethylene terephthalate resin fiber (thickness 40 mm, density 40 kg / m 3 ), and the resistance layer 32 is a spunbond nonwoven fabric (thickness 0.39 mm, basis weight 125 g / m) made of polyester resin fiber. 2 ) and the normal incidence sound absorption coefficient was measured for this sample, which was designated Comparative Example 14. The average normal incidence sound absorption coefficient values ​​are shown in FIG.

[0036] (Comparative Examples 15 to 18) The normal incidence sound absorption coefficient was measured for Example 1, Example 6, Comparative Example 1, and Comparative Example 6 as Comparative Examples 15 to 18 which did not have the protective layer 33. The average normal incidence sound absorption coefficient values ​​are shown in FIG.

[0037] As a result of comparing Example 1 and Comparative Example 1, the normal incidence sound absorption coefficient was higher in both the cases of 1600 to 2000 Hz and 1000 to 2000 Hz in Example 1. Similarly, as a result of comparing the same numbers in Example 2 and Comparative Example 2, and from Example 10 to Comparative Example 10, each Example had a higher normal incidence sound absorption coefficient. As shown in Comparative Examples 15 to 18, in the sound-absorbing material 3 not having a protective layer 33, Comparative Examples 16 and 18 in which the base layer 31 has a basis weight of 40 have the same or higher normal incidence sound absorption coefficient as Comparative Examples 15 and 17 in which the base layer 31 has a basis weight of 22 despite having the same configuration. Therefore, it has been confirmed that, depending on the combination of a specific protective layer 33 and resistance layer 32, a base layer 31 with a smaller basis weight exhibits superior sound absorption performance.

[0038] In particular, in the resistance layer 32, the air flow resistance is 1 kPa·sec / m or more, or the flow resistance is 2 kPa·sec / m 2 When the above conditions are satisfied, the normal incidence sound absorption coefficients at 1600 to 2000 Hz and 1000 to 2000 Hz are excellent and preferable. Specifically, in Examples 1 to 4 and Examples 5 to 9, the normal incidence sound absorption coefficient was 0.85 or more, and in Examples 1 to 4, in which the sound absorbing material 3 was relatively thick and the sound absorbing performance was considered to be relatively high, the normal incidence sound absorption coefficient was 0.9 or more. The frequency range of 1600Hz to 2000Hz, in which the average normal incidence sound absorption coefficient was calculated and compared, was selected as the range in which the sound pressure level is considered to be high for noise when a Shinkansen is running at high speed, and was determined by referring to Figure 6 in "Evaluation of the contribution of each sound source of the sound from the bottom of the vehicle when running at high speed" in the abstract of the 266th Railway Technical Research Institute Monthly Presentation held on April 17, 2013. In other words, the sound absorbing panel 1 formed using the sound absorbing material 3 of Examples 1 to 6 can effectively absorb noise generated when a train travels at high speed on a railway.

[0039] Furthermore, it was confirmed that excellent sound absorbing performance was exhibited in Examples 1 and 6, in which the airflow resistance and flow resistance of the resistance layer 32 were in the range of 0.9 to 1.1 times the airflow resistance and flow resistance of the protective layer 33, as described above. As a result, excellent sound absorbing performance was exhibited even when the same material was used for the protective layer 33 and the resistance layer 32 within the range satisfying the above-mentioned upper limit, so that the material can be standardized and the sound absorbing panel 1 can be assembled without worrying about the front and rear, resulting in excellent workability.

[0040] The sound-absorbing panel 1 according to the present invention is not limited to the above-described embodiment, and various modifications are possible without departing from the gist of the present invention. For example, the sound-absorbing panel 1 has a through hole h in the shape of a small circular hole that allows sound from a sound source provided on the front panel 23 to pass through, but this is not limited to this and the hole may be formed in other shapes, such as a through hole other than a circle or a slit-like long hole.

[0041] Further, the sound-absorbing panel 1 has only one sound-absorbing material 3 disposed behind the front panel 23, but this is not limited thereto, and a plurality of sound-absorbing materials 3 may be disposed side by side vertically or horizontally. [Explanation of symbols]

[0042] 1. Sound absorbing panels 2 Main unit 21 Vertical Frame 22 Horizontal frame 23 Front plate 24 Soundproofing board 3. Sound-absorbing materials 31 Base material layer 32 Resistance layer 33 Protective layer 4. Air Layer F frame h Through hole

Claims

1. A sound-absorbing panel having a front panel having a through hole and arranged on a sound source side, a sound-absorbing material, an air layer, and a sound-insulating plate in this order, The sound-absorbing material has a protective layer, a base layer, and a resistance layer in this order from a sound source side, The base layer is made of a breathable material with a flow resistance of 5 kPa·sec / m ２ Below is The protective layer is made of a breathable material with a flow resistance of 1 MPa·sec / m ２ That's all. The resistance layer is made of a breathable material, and the flow resistance of the resistance layer is 0.9 to 2 times that of the protective layer. A sound absorbing panel characterized by:

2. 2. The sound-absorbing panel according to claim 1, wherein the resistance layer has an airflow resistance of 1 or more, or a flow resistance of 2 or more.

3. 3. The sound-absorbing panel according to claim 2, wherein the resistance layer has an airflow resistance and a flow resistance that are 0.9 to 1.1 times the airflow resistance and the flow resistance of the protective layer.

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