Sound absorption sheet

Abstract

To provide a sound absorption sheet showing excellent sound absorbing performance over a wide range from low to high frequencies.SOLUTION: In a sound absorption sheet, a breathable sheet 20 arranged at a sound source side, a front film 30, sound absorbing material 40, a back film 50, and a sound insulation sheet 60 are arranged in this order in a thickness direction. Excellent sound absorbing performance is shown over a wide range of 1000 to 5000 Hz as a frequency range, by constituting the sound absorption sheet 10 in such a manner that the thickness of the front film 30 and the back film 50 is 3 to 22 μm, and the thickness of the sound absorbing material 40 is 15 to 25 μm.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a sound-absorbing sheet that absorbs noise generated during railway or road construction work. [Background technology]

[0002] Railway and road construction projects usually have a set construction period, and soundproofing facilities to protect against noise generated during construction are installed only during the construction period. Therefore, even during construction, if the construction site moves, the soundproofing facilities must also be moved accordingly. Once the construction is completed, they are dismantled and stored in a storage location or transported for use in other construction projects. For this reason, general soundproofing panels, such as those made of sound-absorbing material inside a metal box, are not suitable for use in such temporary soundproofing facilities. Therefore, soundproofing sheets for temporary soundproofing facilities are used, which are made by covering soundproofing materials with a combination of fabric, textile, resin film, etc.

[0003] Such soundproof sheets can be folded and rolled up, making them easy to transport, and if eyelets are provided at the corners or edges of the soundproof sheet, it can be used simply by hanging it on temporary supports or the like set up at the construction site.

[0004] For example, in Patent Document 1, the applicant has proposed a soundproof sheet in which "a sound-absorbing material 2 is inserted between a protective material 1 and a sound-insulating material 3, the protective material 1 is breathable and water-resistant, the sound-absorbing material 2 is covered with a thin resin film 21, the sound-insulating material 3 is a synthetic resin sheet, the peripheral portions of the protective material 1 and the sound-insulating material 3 are sewn together, and further the protective material 1, the sound-absorbing material 2, and the sound-insulating material 3 are sandwiched at appropriate locations within the peripheral portions." [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Jikko No. 57-19760 Summary of the Invention [Problem to be solved by the invention]

[0006] The soundproof sheet shown in Patent Document 1 has a protective material 1 that is breathable and waterproof, making it difficult for rainwater and the like to penetrate inside, and a resin film that prevents the glass wool or rock wool used in the soundproofing material 3 from getting out. This prevents the sound-absorbing material from getting wet with rainwater and the like, which can reduce the sound-absorbing effect, even when used outdoors.

[0007] Incidentally, as described in Patent Document 1, thinner resin films tend to exhibit a greater sound absorbing effect, but they also tend to tear more easily. [Means for solving the problem]

[0008] In order to solve the above problems, the inventors of the present invention have conducted extensive research into the configuration of sound-absorbing materials. As a result, they have discovered that by setting the resin film to a predetermined thickness and the sound-absorbing material to a predetermined thickness, excellent sound-absorbing performance can be achieved over a wide range of frequencies from low to high, leading to the completion of the present invention.

[0009] In other words, the sound-absorbing sheet of the present invention is a sound-absorbing sheet comprising a breathable sheet placed on the sound source side, a front film, a sound-absorbing material, a rear film, and a sound-insulating sheet arranged in this order in the thickness direction, and is characterized in that the thicknesses of the front film and rear film are 3 to 22 μm, and the thickness of the sound-absorbing material is 15 to 25 μm.

[0010] In the present invention, the sound-absorbing material has a length direction and a width direction, and the front surface on the front film side has alternating recesses and protrusions formed at predetermined intervals in the length direction or width direction, and it is preferable that the rear surface on the rear film side of the sound-absorbing material also has alternating recesses and protrusions formed at predetermined intervals. [Effects of the Invention]

[0011] According to the sound-absorbing panel of the present invention, if a non-breathable film is placed in front of the sound-absorbing material, noise is more likely to be reflected, improving sound insulation but there is a risk of a decrease in sound absorption performance. However, by making the film to a specified thickness, the panel exhibits excellent sound absorption performance over a wide wavelength range. [Brief explanation of the drawings]

[0012] [Figure 1] 1A, 1B, and 1C are explanatory views showing an embodiment of a sound-absorbing panel according to the present invention, in which (a) is a front view, (b) is a right side view, and (c) is a rear view. [Figure 2] FIG. 2 is a schematic cross-sectional view taken along line AA in FIG. [Figure 3] 1 is a table showing the components constituting each of the sound-absorbing panels of Examples 1 to 6, as well as the sound-absorbing performance and cut resistance. [Figure 4] 1 is a table showing the components constituting the sound-absorbing panels of Comparative Examples 1 to 9, as well as the sound-absorbing performance and cut resistance. DETAILED DESCRIPTION OF THE INVENTION

[0013] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be specifically described with reference to the accompanying drawings. The sound-absorbing sheet 10 shown in FIG. 1 is rectangular and includes a breathable sheet 20 (located on the sound source side), a front film 30, a sound-absorbing material 40, a rear film 50, and a sound-insulating sheet 60, arranged in this order in the thickness direction. The breathable sheet 20 and the sound-insulating sheet 60 are joined together to form the sound-absorbing sheet 10. In this embodiment, the breathable sheet 20 and the sound-insulating sheet 60 are joined by sewing their peripheral edges. In FIG. 1, the sewing location 11 is indicated by a vertically elongated rectangular dashed line. This prevents the front film 30, sound-absorbing material 40, and rear film 50, which are located between the breathable sheet 20 and the sound-insulating sheet 60, from protruding. In this embodiment, the joining is performed by sewing, but adhesives may also be used.

[0014] The breathable sheet 20 can be made of known materials such as woven or nonwoven fabrics made of fibrous materials. Examples of materials that can be used for the breathable sheet 20 include 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; synthetic resins such as acrylic resins, melamine resins, and polyurethane resins; rubber 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. The above-mentioned materials may be used selectively or in combination.

[0015] Furthermore, it is preferable that the breathable sheet 20 have excellent cut resistance. As a result, when the sound-absorbing sheet 10 according to the present invention is used at a railway or road construction site, it will not be easily damaged even if construction materials or equipment come into contact with the sound-absorbing sheet 10 during construction work, or even if flying stones or sand are blown from the road surface or near the railroad tracks by vehicles passing near the construction site.

[0016] Furthermore, it is preferable that the breathable sheet 20 has excellent flame retardancy. This makes it possible to prevent easy combustion and suppress continuous combustion when the sound-absorbing sheet 10 according to the present invention is used at railway or road construction sites, even if there are sparks generated by cutting work or flames from firearms such as burners during construction work.

[0017] The front film 30 is made of synthetic resin. Generally, films have poorer breathability than nonwoven fabrics, which means they repel noise and reduce their sound-absorbing effect. However, in the present invention, it has been discovered that by setting the thickness of the front film 30 to a predetermined value, excellent sound-absorbing performance can be achieved. On the other hand, compared to nonwoven fabrics, films are less permeable to moisture, and can suppress the movement of moisture from the front film 30 side to the sound-absorbing material 40 side due to rainwater or condensation.

[0018] Examples of materials for the front film 30 include polyethylene, polypropylene, polyester, and polyamide. The thickness of the front film 30 is preferably 5 to 20 mm. If the thickness is less than 5 mm, the film is prone to tearing. If the thickness exceeds 20 mm, the sound absorption performance is reduced. In this embodiment, the material for the front film 30 is a polyester-based resin, more specifically, polyethylene terephthalate. This makes the front film 30 less prone to tearing than polyethylene or polypropylene and less hygroscopic than polyamide, thereby preventing a decrease in sound absorption performance due to moisture absorption or moisture permeation of the front film 30.

[0019] The sound-absorbing material 40 can be made of known materials used as sound-absorbing materials, such as woven or nonwoven fabrics made of fibrous materials, or foams made of synthetic resins. Examples of materials that can be used for the sound-absorbing material 40 include 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; synthetic resins such as acrylic resins, melamine resins, and polyurethane resins; rubber 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. The above materials may also be used selectively or in combination. When nonwoven fabric made of fibrous materials is used for the sound-absorbing material 40, it may be formed into a cloth-like sheet or a cotton-like material.

[0020] The sound-absorbing material 40 has a length direction and a width direction, and on the front surface on the side of the front film 30, concave portions and convex portions are formed alternately at predetermined intervals in the length direction or width direction, and it is preferable that on the rear surface on the side of the rear film 50, concave portions and convex portions are also formed alternately at predetermined intervals. This makes it easier to roll up the sound-absorbing sheet when carrying it, making it easier to carry. In other words, when rolling up, the breathable sheet 20 side may be on the inside, or the breathable sheet 20 side may be on the outside, and since the concave portions and convex portions are formed alternately on both surfaces, rolling up is easy. It is preferable that the rear surface has convex and concave portions positioned at positions corresponding to the concave and convex portions on the front surface, since this makes winding even easier.

[0021] The rear film 50 is made of a synthetic resin. Examples of the material for the rear film 50 include polyethylene, polypropylene, polyester, and polyamide. The rear film 50 may be made of the same material and thickness as the front film 30. This allows the use of common materials.

[0022] In this embodiment, the sound-absorbing material 40 is disposed between the front film 30 and the rear film 50, and the peripheral edges of the front film 30 and the rear film 50 are bonded together. This makes it possible to prevent rainwater and the like from penetrating the sound-absorbing material 40. The bonding method may be an adhesive, or the front film 30 and the rear film 50 may be welded together.

[0023] The sound-insulating sheet 60 is made of synthetic resin. Generally, films have poorer breathability than nonwoven fabrics, so sound that passes through the sound-absorbing material 40 from the noise source is reflected by the sound-insulating sheet 60, and is then absorbed again by the sound-absorbing material 40, thereby reducing noise. Examples of materials for the sound-insulating sheet 60 include polyethylene, polypropylene, polyester, polystyrene, polyamide, polyvinyl chloride, polyvinylidene chloride, and acrylic resins.

[0024] An example of the sound absorbing sheet 10 according to the present invention and a comparative example will be described below.

[0025] Example 1 The fabric consisted of a breathable sheet 20 made of a woven polyester resin fiber coated with polyvinyl chloride resin (thickness: 0.84 mm, Shady Screen 4000N, manufactured by Hiraoka Ori-sen Co., Ltd.), a front film 30 made of a polyester resin sheet (thickness: 5 μm) whose main component was polyethylene terephthalate, and a cotton-like PET fiber nonwoven fabric (thickness: 20 mm, density: 40 kg / m) made of polyethylene terephthalate resin fiber. 3The sound-absorbing sheet 10 of Example 1 was formed by arranging, in this order, a sound-absorbing material 40 made of a polyester resin sheet (thickness: 5 μm) whose main component is polyethylene terephthalate, a rear film 50 made of a polyester resin sheet (thickness: 5 μm) whose main component is polyvinyl chloride, and a sound-insulating sheet 60 made of a resin sheet (thickness: 1 mm) whose main component is polyvinyl chloride. Note that, since the present embodiment is intended to evaluate the sound absorption performance and cut resistance described below, the breathable sheet 20 and the sound-insulating sheet 60, and the front film 30 and the rear film 50 are not joined together.

[0026] [Sound absorption performance] [Measurement of normal incidence sound absorption coefficient] The method for measuring the normal incident sound absorption coefficient in Example 1 will be described. First, for the sound-absorbing sheet 10 of Example 1, each component was cut into a circle with a diameter of 29 mm, and the breathable sheet 20, front film 30, sound-absorbing material 40, rear film 50, and sound-insulating sheet 60 were stacked in this order to prepare a measurement sample. Next, the normal incident sound absorption coefficient of the measurement sample was measured in accordance with JIS A 1405. Specifically, measurements were taken every 2 Hz in the frequency range from 500 Hz to 6400 Hz using a normal incidence sound absorption coefficient measurement system, Type 4206 acoustic impedance tube (manufactured by Brüel & Kjær), and normal incidence sound absorption coefficient measurement software, MS1021 (manufactured by Spectris Inc.). From the measurement results, the normal incidence sound absorption coefficient values ​​at 1000, 2000, 3150, 4000, and 5000 Hz were calculated. If the sound absorption coefficient was 0.5 or higher at any of the frequencies, it was determined that the material had sufficient sound absorption performance and was rated as "Good." If the sound absorption coefficient was less than 0.5 at any of the frequencies, it was determined that the material did not have sufficient sound absorption performance and was rated as "Poor." The sound absorption coefficient measurement results and sound absorption performance evaluation results are shown in Figure 3.

[0027] [Cut resistance] In Example 1, a breathable sheet 20 (100 mm × 100 mm) was prepared as a sample. Then, an abrasive: Alundum #120 was sprayed from a Φ5 mm outlet at a position 50 mm away from the fixed sample at an air pressure of 3.3 kg / cm. 2The test was conducted by discharging the liquid at a rate of 0.01%. If no holes had appeared in the sample 30 seconds after the start of the test, the sample was deemed to have sufficient cut resistance and was rated as "Good." If defects such as tears or holes had appeared in the sample, the sample was deemed to have insufficient cut resistance and was rated as "Poor." The cut resistance evaluation results are shown in Figure 3.

[0028] Example 2 In Example 2, the thickness of the front film 30 and the rear film 50 were changed to 12 μm compared to Example 1, and measurements of the normal oblique incidence sound absorption coefficient, evaluation of sound absorption performance, and evaluation of cut resistance were carried out. The results are shown in FIG. 3. In the evaluation of cut resistance, Example 2 uses the same breathable sheet 20 as Example 1, so the evaluation results of Example 1 were used. Hereinafter, in the evaluation of cut resistance, if a performance evaluation has already been carried out on the breathable sheet 20 of each Example, the evaluation results were used.

[0029] Example 3 In Example 3, the thickness of the front film 30 and the rear film 50 was changed to 16 μm in comparison with Example 1, and the normal oblique incidence sound absorption coefficient, sound absorption performance, and cut resistance were measured. The results are shown in FIG.

[0030] Example 4 In Example 4, the thickness of the breathable sheet 20 was changed to 0.56 mm in comparison with Example 1, and the normal oblique incidence sound absorption coefficient, sound absorption performance, and cut resistance were measured. The results are shown in FIG.

[0031] Example 5 In Example 5, a film made of high-density polyethylene resin sheets (thickness: 10 μm) containing polyethylene as the main component was used as the front film 30 and the rear film 50 in comparison with Example 1. The normal oblique incidence sound absorption coefficient was measured, and evaluations of sound absorption performance and cut resistance were carried out. The results are shown in Figure 3.

[0032] Example 6 In Example 7, the thickness of the sound-insulating sheet 60 was changed to 2 mm in comparison with Example 2, and measurements of the normal oblique incidence sound absorption coefficient, evaluation of sound absorption performance, and evaluation of cut resistance were carried out. The results are shown in FIG.

[0033] (Comparative Example 1) The breathable sheet 20 was a woven fabric (thickness 0.49 mm) made of polyester resin fiber, the front film 30 was a polyethylene resin sheet (thickness 20 μm) whose main component was polyethylene, and the sound absorbing material 40 was glass wool (thickness 25 mm, density 32 kg / m 3 ), a polyethylene-based resin sheet (thickness 20 μm) mainly composed of polyethylene as the back film 50, and a resin sheet (thickness 1.5 mm) mainly composed of polyvinyl chloride as the sound insulation sheet 60 were used as Comparative Example 1. Measurement of normal oblique incidence sound absorption coefficient, evaluation of sound absorption performance, and evaluation of cut resistance were carried out for this sample. The results are shown in Figure 4.

[0034] (Comparative Example 2) In contrast to Example 1, Comparative Example 2 was prepared by changing the thickness of the breathable sheet 20 to 0.3 mm and not using the front film 30 or the rear film 50. The normal oblique incidence sound absorption coefficient was measured, and evaluations of sound absorption performance and cut resistance were carried out. The results are shown in Figure 4.

[0035] (Comparative Example 3) In contrast to Example 2, Comparative Example 3 was prepared by changing the breathable sheet 20 to a woven glass fiber fabric (0.34 mm thick, Clear Lightron D-3000, manufactured by Hiraoka Orishin Co., Ltd.) coated with polyvinyl chloride resin (0.34 mm thick), and the front film 30 and rear film 50 to 12 μm thick. Measurement of the normal oblique incidence sound absorption coefficient, evaluation of sound absorption performance, and evaluation of cut resistance were carried out. The results are shown in Figure 4.

[0036] Comparative Example 4 In contrast to Example 1, Comparative Example 4 was prepared by changing the thickness of the front film 30 and the rear film 50 to 25 μm, and the normal oblique incidence sound absorption coefficient, sound absorption performance, and cut resistance were measured. The results are shown in FIG.

[0037] (Comparative Example 5) In contrast to Example 1, Comparative Example 5 was prepared without the front film 30 and the rear film 50, and was subjected to measurement of the normal oblique incidence sound absorption coefficient, evaluation of sound absorption performance, and evaluation of cut resistance. The results are shown in FIG.

[0038] (Comparative Example 6) In contrast to Example 2, Comparative Example 6 was prepared without using the breathable sheet 20, and the normal oblique incidence sound absorption coefficient was measured and the sound absorption performance was evaluated. The results are shown in FIG.

[0039] (Comparative Example 7) In contrast to Example 2, Comparative Example 7 was prepared by changing the thickness of the sound-absorbing material 40 to 10 mm, and the normal oblique incidence sound absorption coefficient was measured, and evaluations of sound absorption performance and cut resistance were carried out. The results are shown in FIG.

[0040] (Comparative Example 8) In Comparative Example 8, the thickness of the front film 30 and the rear film 50 were changed to 50 mm in comparison with Example 1, and the normal oblique incidence sound absorption coefficient, sound absorption performance, and cut resistance were measured. The results are shown in Figure 4.

[0041] (Comparative Example 9) In Comparative Example 9, the sound-absorbing material 40 had a thickness of 10 mm, as compared to Example 1. The normal oblique incidence sound absorption coefficient was measured, and the sound absorption performance and cut resistance were evaluated. The results are shown in FIG. do. [Explanation of symbols]

[0042] 10 Sound-absorbing sheet 20 Breathable Sheet 30 Previous Film 40 Sound-absorbing material 50 After Film 60 Soundproofing Sheet

Claims

1. A sound-absorbing sheet including a breathable sheet disposed on the sound source side, a front film, a sound-absorbing material, a rear film, and a sound-insulating sheet arranged in this order in the thickness direction, The thickness of the front film and the rear film is 3 to 22 μm, The thickness of the sound absorbing material is 15 to 25 μm. A sound-absorbing sheet characterized by:

2. The sound absorbing material has a length direction and a width direction, and the front surface of the front film side has recesses and protrusions formed at predetermined intervals in the length direction or width direction, and the rear surface of the sound absorbing material on the rear film side also has recesses and protrusions formed at predetermined intervals.

2. The sound-absorbing sheet according to claim 1.

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