JP2007262765A - Sound absorbing material and sound absorbing panel - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sound absorbing material which is good in sound absorbing properties and ventilation performance, and excellent in immersion-proof performance, and to provide a sound absorbing panel. <P>SOLUTION: The sound absorbing material 1 is formed of a plate member 2 having a plurality of through holes 3 with a diameter of 30 μm or less perforated therein in a plate thickness direction. Alternatively the sound absorbing material is formed of a plate member having a plurality of through holes with a diameter of 30 μm or more and 400 μm or less perforated therein in a plate thickness direction, and makes one surface thereof water repellent. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a sound absorbing material and a sound absorbing panel.

  In recent years, when designing public spaces such as halls and outliums, in order to ensure daylighting and ventilation, the boundary with the outside is partitioned by a panel body made of a transparent material such as glass, and the panel body itself Many designs such as an open / close mechanism are adopted. By the way, there is a characteristic that sound is likely to reverberate inside a hall, an outerium or the like, and in order to prevent the occurrence of this reverberating sound, the panel body may be constituted by a sound absorbing panel.

  As an example of the sound absorbing panel, there is known a sound absorbing panel in which a sound absorbing material in which a through-hole is provided in a transparent plate-shaped member and a non-porous plate such as a plate glass are disposed at a predetermined interval. . In this sound absorbing panel, a back air layer is provided between the sound absorbing material and the non-porous plate, and the back air layer and the through hole of the sound absorbing material are communicated with each other, so that the so-called Helmholtz resonance structure is formed. Is formed. And when installing this sound-absorbing panel in a hall | hole, an outerium, etc., the sound-absorbing material is arrange | positioned indoors, and non-porous boards, such as plate glass, are arrange | positioned on the outdoor side.

Furthermore, as another example of the sound absorbing panel, there is also known a sound absorbing panel in which two sound absorbing materials each having a plate-like member provided with a through hole are prepared, and the respective sound absorbing materials are disposed with a predetermined interval therebetween. (Patent Document 1).
JP 2005-173398 A

  In the above-mentioned sound absorbing panel composed of a sound absorbing material and a non-porous plate such as a plate glass, the size of the through hole provided in the sound absorbing material is about several millimeters, so that ventilation performance is ensured by opening the plate glass. When raining, there is a problem that rainwater enters through a through hole provided in the sound absorbing material. Further, if the through hole is filled with rainwater, there is a possibility that a predetermined sound absorption characteristic cannot be obtained.

  Also, in the above-mentioned sound absorbing panel configured by combining two sound absorbing materials, the size of the through hole provided in the sound absorbing material is about several millimeters, so that the ventilation performance is ensured, but the sound absorbing material at the time of rain There was a problem that rainwater entered from the through hole provided in the. Further, if the through hole is filled with rainwater, there is a possibility that a predetermined sound absorption characteristic cannot be obtained.

  The present invention has been made in view of the above circumstances, and an object thereof is to provide a sound absorbing material and a sound absorbing panel that have sufficient sound absorption characteristics and ventilation performance and are excellent in water resistance.

In order to achieve the above object, the present invention employs the following configuration.
The sound absorbing material of the present invention is characterized by comprising a plate-like member provided with a plurality of through holes having a diameter of 30 μm or less along the plate thickness direction.
Further, the sound absorbing material of the present invention is composed of a plate-like member provided with a plurality of through holes having a diameter of 30 μm or more and 400 μm or less along the plate thickness direction, and water repellent treatment is performed on one surface side of the plate-like member. It is characterized by that.
In the sound-absorbing material of the present invention, it is preferable that the plate-like member is made of a translucent material.

According to the above sound absorbing material in which the diameter of the through hole is 30 μm or less, since the diameter of the through hole is sufficiently small, even when rainwater is poured into the sound absorbing material due to rain or the like, There is no risk of rainwater infiltrating from one side to the other.
Further, according to the above-described sound absorbing material in which the diameter of the through hole is 30 μm or more and 400 μm or less, since the water repellent treatment is performed on the one surface side, the sound absorbing material has a relatively large diameter of the through hole, but is rained or the like. Even when rainwater is poured onto the plate, there is no possibility of rainwater infiltrating from one side of the plate member to the other side due to the effect of the water repellent treatment.
In any of the above sound absorbing materials, ventilation can be performed through the through hole.
Furthermore, according to the above sound absorbing material, since the plate-like member is made of a translucent material, it is possible to ensure daylighting.

Next, the sound-absorbing panel of the present invention has one sound-absorbing material composed of a plate-like member provided with a plurality of through-holes along the plate thickness direction, and a plurality of through-holes with a diameter of 30 μm or less along the plate thickness direction. The other sound-absorbing material composed of the provided plate-like member is disposed relative to each other with a predetermined interval, and the other sound-absorbing material is installed facing the outside with respect to the one sound-absorbing material. It is characterized by being.
The sound absorbing panel of the present invention includes a sound absorbing material made of a plate-like member provided with a plurality of through holes along the plate thickness direction, and a plurality of through holes having a diameter of 30 μm or more and 400 μm or less along the plate thickness direction. And another sound-absorbing material made of a plate-like member having a water-repellent treatment on one side thereof, and are arranged relative to each other at a predetermined interval, and the other sound-absorbing material with respect to the one sound-absorbing material Is installed facing the outside, and the one surface subjected to the water repellent treatment is directed to the outdoor side.
Furthermore, the sound absorbing panel of the present invention includes a non-porous plate made of a translucent material and a sound absorbing material made of a plate-like member provided with a plurality of through holes having a diameter of 30 μm or less along the plate thickness direction. The non-perforated plate is disposed facing the outside with respect to the sound absorbing material.
Furthermore, the sound-absorbing panel of the present invention is provided with a non-perforated plate made of a translucent material and a plurality of through-holes having a diameter of 30 μm or more and 400 μm or less along the thickness direction and a water repellent treatment on one side. A sound absorbing material made of a plate-like member is disposed relative to each other at a predetermined interval, and the non-perforated plate is installed facing the sound absorbing material outdoors, and the water repellent treatment of the sound absorbing material is performed. The one surface that has been subjected to is directed to the outdoor side.
In each of the above sound absorbing panels, it is preferable that each of the plate-like members is made of a translucent material.
Moreover, in each said sound-absorbing panel, it is preferable that the non-porous plate is provided with an opening / closing mechanism.

According to the above sound absorbing panel, the air absorbing layer is provided between the sound absorbing materials or between the sound absorbing material and the non-porous plate by arranging the sound absorbing materials or the sound absorbing material and the non-porous plate to face each other. Thereby, a so-called Helmholtz resonator is constituted by the through-hole and the air layer of the sound absorbing material, and the sound absorbing characteristics can be greatly improved.
In addition, the other sound absorbing material in which a plurality of through holes having a diameter of 30 μm or less are provided on the outdoor side, or a plurality of through holes having a diameter of 30 μm or more and 400 μm or less are provided on the outdoor side and on one surface side. By arranging another sound absorbing material that has been subjected to water repellent treatment, there is no possibility of rainwater infiltrating from one side of the sound absorbing material to the other side even when rainwater is poured into the sound absorbing material due to rain or the like.
Furthermore, when a plate-like non-porous plate made of a translucent material is arranged on the outdoor side and any of the above sound absorbing materials is arranged on the indoor side, the non-porous plate on the outdoor side is opened by an opening / closing mechanism. Even in such a case, the infiltration of rainwater is prevented by the sound absorbing material installed on the indoor side.

As described above, according to the sound absorbing material and the sound absorbing panel of the present invention, it is possible to provide a sound absorbing material and a sound absorbing panel that have sufficient sound absorbing characteristics and ventilation performance and are excellent in water resistance.
Further, the sound absorbing material and sound absorbing panel of the present invention can be used as a construction material when constructing public spaces such as halls, outliums, railway stations, airport lobbies, offices, houses and the like. In particular, it can be used for wall materials, roof materials, door materials and the like.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. The drawings referred to in the following description are for explaining the sound absorbing material, the sound absorbing panel, and the method of manufacturing the sound absorbing material. The size, thickness, dimensions, etc. of each part shown in the drawings are the same as those of the actual sound absorbing material, etc. It may be different from the dimensional relationship.

"Sound absorbing material"
(First example of sound absorbing material)
A first example of the sound absorbing material of this embodiment will be described with reference to the drawings. FIG. 1 shows a perspective view of the sound absorbing material of this example, and FIG. 2 shows a schematic sectional view of the sound absorbing material of this example.
As shown in FIG. 1, the sound-absorbing material 1 of this example is composed of a plate-like member 2 made of a translucent material, and is manufactured by a manufacturing method described later. This plate-like member 2 has one surface 2a and the other surface 2b having the largest area among the respective surfaces that are the outer surfaces of the plate-like member. The one surface 2 a and the other surface 2 b are opposed to each other along the thickness direction of the plate-like member 2. The one surface 2a and the other surface 2b are provided with a plurality of through holes 3 having a diameter of 30 μm or less as shown in FIG. Moreover, the material of the plate-shaped member 2 is comprised from the photosensitive glass material so that it may mention later.

The thickness t ₁ of the plate-like member 2 is preferably in the range of 0.5 mm or more and 2 mm or less, although it depends on the opening ratio of the through holes 3 as described later. The thickness t ₁ of the plate-like member 2 corresponds to the length of the through hole 3 in the plate thickness direction. If the thickness t ₁ (length of the through hole) of the plate-like member 2 is 0.5 mm or more, it is preferable that the strength of the plate-like member 2 itself is not lowered and the sound absorption characteristics are not lowered. Further, _(length of the through-hole) plate-like member 2 in the thickness t ₁ is equal to 2mm or less, without damaging the workability increased weight, but also the sound absorbing property is not lowered.

As shown in FIG. 2, the through hole 3 extends along the thickness direction of the plate-like member 2 and penetrates the plate-like member 2. The through hole 3 preferably has a circular shape in plan view, but may have an elliptical shape, a rectangular shape, or a polygonal shape with curved corners. The diameter d ₁ of the through-hole 3 (long diameter in the case of an ellipse, square, or diagonal length in the case of a square having a curved surface) is preferably in the range of 30 μm or less, and more preferably in the range of 5 μm to 30 μm.
The diameter d ₁ of the through-hole 3 may also uniform for each through hole, may be different for each through-hole in the range of 30 [mu] m.
When the diameter d ₁ of the through hole 3 exceeds 30 μm, it is not preferable because rain water easily enters the through hole 3 when rain water or the like is poured into the sound absorbing material 1.

Further, the shape and size of the through-hole 3 in plan view are preferably constant along the thickness direction of the plate-like member 2, but the size gradually changes along the thickness direction of the plate-like member 2. Also good. That is, each of the through holes 3 shown in FIG. 2 has a constant shape and size in plan view along the thickness direction of the plate-like member 2, and the wall surface 3a of the through hole 3 is in relation to the one surface 2a and the other surface 2b. However, the wall surface of the through hole 3 may be a tapered surface.
Moreover, it is preferable that each through-hole 3 ... is arranged in the planar view lattice shape or the staggered lattice shape at equal intervals. What is necessary is just to set the pitch of each through-hole corresponding to the aperture ratio of the through-hole mentioned later.

Next, a preferable range of the opening ratio σ ₁ of the through holes 3... _Is a relationship between the thickness t ₁ of the plate-like member 2, the diameter d _{1 of the} through holes, and the maximum sound absorption coefficient α _max required for the sound absorbing material 1. It explains from.
The maximum sound absorption coefficient α _max required for the sound absorbing material 1 of this example is preferably 50% or more, more preferably 70% or more, and most preferably 90% or more. Here, the maximum sound absorption coefficient α _max is a so-called normal incidence sound absorption coefficient, which is a maximum sound absorption coefficient in a frequency band of 10 Hz to 10000 Hz. That is, the maximum sound absorption coefficient α _max of 50% or more means that the maximum value of the normal incident sound absorption coefficient in the frequency band of 10 Hz to 10000 Hz is 50% or more. In the sound absorbing material 1 of this example, it is desirable that at least the maximum sound absorption coefficient α _max is 50% or more. When the maximum sound absorption coefficient α _max is less than 50%, it is not desirable as a sound absorbing material.

Further, the thickness t ₁ of the plate-like member 2 is preferably in the range of 0.5 mm to 2 mm as described above. Furthermore diameter d ₁ of the through hole is preferably as follows 30μm described above.
In order to ensure a maximum sound absorption coefficient α _max of 50% or more in the range of the thickness t ₁ and the diameter d ₁ , the opening ratio σ ₁ of the through holes 3. In order to secure the maximum sound absorption coefficient α _max of 70% or more, the aperture ratio σ ₁ may be set to 20% or more. Furthermore, in order to secure the maximum sound absorption coefficient α _max of 90% or more, the aperture ratio σ ₁ may be set to 35% or more. If the aperture ratio σ ₁ is out of these ranges, the desired maximum sound absorption coefficient α _max cannot be obtained. Moreover, it is preferable that the upper limit of the aperture ratio σ ₁ is 80% or less from the viewpoint that rainwater can be prevented from entering during rain and the mechanical strength of the sound absorbing material 1 can be improved.

The opening ratio σ ₁ of the through holes 3 is the ratio of the opening area of the through holes 3 to the area of the one surface 2a or the other surface 2b. The aperture ratio σ ₁ can be controlled by adjusting the shape of the mask when exposing the photosensitive glass in the manufacturing method described later.

The sound absorbing material 1 is preferably arranged so that the one surface 2a or the other surface 2b faces the sound source position. The surface of the sound absorbing material 1 opposite to the sound source position is in contact with the air layer, and the air layer and the through holes 3 of the sound absorbing material 1 communicate with each other to form a so-called Helmholtz resonator, thereby obtaining sound absorbing performance. It is done.
The sound absorption performance of the Helmholtz resonator includes the thickness t ₁ (length of the through hole) of the plate-like member 2, the diameter d _{1 of} the through hole 3, the interval between the through holes 3, the opening ratio σ ₁ of the through holes 3, and the like. Therefore, it may be set as appropriate within the optimum range described above so that the maximum sound absorption rate can be obtained in accordance with acoustic characteristics such as the frequency of the sound to be absorbed.

Next, the manufacturing method of the sound absorbing material of this example will be described.
In the sound absorbing material 1 of this example, a mask having a predetermined pattern is brought into close contact with a photosensitive glass serving as a plate-like member, and the photosensitive glass is exposed by irradiating ultraviolet rays from the mask, and is exposed in the photosensitive glass. A latent image forming step for forming a latent image corresponding to the portion, a heat treatment of the processed glass after the latent image forming step, a crystallization step for crystallizing the exposed portion, and a processing glass after the crystallization step are etched. The crystallized exposed portion can be manufactured by dissolving and removing and passing through the front and back. Moreover, you may add the process of grind | polishing process glass after a melt | dissolution process. Hereinafter, each step will be described in detail.

(Latent image forming process)
In the latent image forming step, first, photosensitive glass is prepared as a starting material. This photosensitive glass is a translucent material, and finally becomes the plate-like member 2 of the sound absorbing material 1 of this example. This photosensitive glass contains any photosensitive component and can be used as long as it exhibits photosensitivity, but for example, by weight, SiO ₂ : 55 to 85%, Al ₂ O ₃ : 2 to 20%, Li ₂ O: 5 to 15%, SiO ₂ + Al ₂ O ₃ + Li ₂ O> 85% as basic components, Au: 0.001 to 0.05%, Ag: 0.001 to 0.5%, Cu ₂ It is preferable to use photosensitive glass containing O: 0.001 to 1% as a photosensitive metal component and further containing CeO2: 0.001 to 0.2% as a photosensitizer.

In addition, as a mask used for forming the pattern of the photosensitive glass, any mask may be used as long as it has a predetermined pattern and is in close contact with the photosensitive glass to enable selective exposure of the photosensitive glass. Although a thing can also be used, for example, a mask made by forming a pattern made of a chromium film on a transparent thin glass sheet can be used. When the mask is brought into close contact with the photosensitive glass and exposed from above the mask, nuclei composed of particles of photosensitive metal (Ag, Au, etc.) are generated in the exposed portion, and a latent image is formed. As this exposure means, it is preferable to irradiate ultraviolet rays for a predetermined time (for example, 10 seconds to 2 minutes) using, for example, a mercury lamp, a mercury-xenon lamp or the like.
Further, since the diameter d ₁ and the arrangement and the aperture ratio σ ₁ of the through holes 3 of the sound absorbing material 1 of this example are determined by the pattern formed on the mask, the pattern formed on the mask has the diameter d ₁ described above. It is desirable to design in consideration of the range of the aperture ratio σ ₁ .

(Crystallization process)
In the crystallization process, the glass on which the latent image is formed, obtained in the previous latent image forming process, is heat-treated. This heat treatment is preferably performed at a temperature of 550 ° C to 610 ° C. The reason why this temperature range is preferable is that if the temperature is lower than 550 ° C., the temperature is too low to have the effect of heat treatment, and if the temperature exceeds 610 ° C., shrinkage occurs and the dimensional accuracy decreases. The heat treatment time is preferably 30 minutes to 5 hours.
By this heat treatment, lithium metasilicate crystal grows with the photosensitive metal particles present in the exposed portion (latent image) as nuclei. Since this lithium metasilicate crystal has the property of being easily dissolved in an acid, etching in the subsequent dissolution process can be performed smoothly.

(Dissolution process)
In the melting step, the glass obtained in the crystallization step is etched with, for example, dilute hydrofluoric acid to dissolve and remove the acid-soluble lithium metasilicate crystal in the exposed portion, thereby penetrating the front and back to form the through holes 3. Form. The concentration, temperature, etching time, etc. of dilute hydrofluoric acid are appropriately determined according to the type and thickness of the glass used. Instead of dilute hydrofluoric acid, a solution obtained by dissolving a salt containing F such as NH ₄ HF ₂ , NaHF ₂ , KHT _2, and K ₂ SiF ₆ in an acid may be used as an etching solution.

(Polishing process)
In the polishing step, one or both sides of the glass obtained in the melting step are polished. This polishing is performed in order to sharpen the edge portion of the through hole and increase the dimensional accuracy.
The sound absorbing material 1 of this example is obtained through the above steps.

As described above, according to the sound-absorbing material 1 of this example, the plurality of through-holes 3 with a diameter of 30 μm or less are provided along the thickness direction of the plate-like member 2. d ₁ is sufficiently small, and there is no possibility of rainwater infiltrating from the one surface 2 a side to the other surface 2 b side of the plate-like member 2.
It is also possible to ventilate through the through hole.
Further, by appropriately setting the opening ratio σ ₁ of the through hole and the thickness t ₁ of the plate-like member 2 within the above ranges, a maximum sound absorption coefficient α _max of at least 50% or more is secured, and at the same time, intrusion of rainwater or the like is prevented. Ventilation performance is ensured. Moreover, it becomes what was excellent also in the daylighting property by comprising the plate-shaped member 2 from a translucent material.

(Second example of sound absorbing material)
Next, a second example of the sound absorbing material will be described.
The sound absorbing material of this example is made of a plate-like member made of a translucent material, like the first sound absorbing material 1, and is manufactured by a manufacturing method described later. The plate-like member is provided with a plurality of through holes having a diameter of 30 μm or more and 400 μm or less along the thickness direction. Further, the material of the plate-like member is made of photosensitive glass as in the first example. Further, one surface of the plate member is subjected to water repellent treatment.

The thickness t ₂ of the plate-like member in this example varies depending on the diameter d ₂ of the through hole and the opening ratio σ ₂ of the through hole as will be described later, but is appropriately set in a range of approximately 0.5 mm to 5 mm. Is preferred. In particular, the thickness t ₂ of the plate member, because the preferred range by the diameter d ₂ of the holes is varied, it is desirable to suitably set in relation to the diameter d ₂ of the through hole. The thickness t ₂ of the plate-like member corresponds to the length of the plate thickness direction of the through hole. If the thickness t ₂ (length of the through hole) of the plate member is 0.5 mm or more, it is preferable that the strength of the plate member itself does not decrease and the sound absorption characteristics do not decrease. Further, _(length of the through-hole) plate-like member having a thickness t ₂ is equal to 5mm or less, without damaging the workability increased weight, but also the sound absorbing property is not lowered.

The through-hole in this example extends along the thickness direction of the plate-like member and penetrates the plate-like member, as in the first example. The shape of the through hole in plan view is preferably a circle, but may be an ellipse, a quadrangle, or a polygon having a curved corner. The diameter d _{2 of the} through hole (in the case of an ellipse, a long diameter, a quadrangle, and in the case of a quadrangle whose corner is a curved surface, the length of a diagonal line) is preferably in the range of 30 μm to 400 μm.
Further, to the diameter d ₂ of the through hole may be the size of the maximum sound absorption coefficient and uniform for each through hole, the frequency of the maximum sound-absorbing rate different for each through-hole in the range of 30~400μm It may be widely dispersed.
If the diameter d ₂ of the through hole is less than 30 [mu] m, it is not preferable because there is a fear that filled the holes in the water-repellent treatment to be described later, the diameter d ₂ of the through hole is greater than 400 [mu] m, rainwater down to sound absorbing material When poured, it is not preferable because rainwater easily enters the through hole.

  Further, the shape and size of the through hole in plan view are preferably constant along the thickness direction of the plate-like member, as in the first example, but the size along the thickness direction of the plate-like member is small. It may change gradually. Moreover, it is preferable that the through holes are arranged in a lattice pattern or a staggered pattern in plan view with an equal interval. What is necessary is just to set the pitch of each through-hole corresponding to the aperture ratio of the through-hole mentioned later.

Next, a preferable range of the aperture ratio σ ₂ of the through hole will be described from the relationship between the thickness t ₂ of the plate-like member 2, the diameter d _{2 of the} through hole, and the maximum sound absorption coefficient α _max required for the sound absorbing material 1. To do.
The maximum sound absorption coefficient α _max required for the sound absorbing material of this example is preferably 50% or more, more preferably 70% or more, and most preferably 90% or more, as in the first example. When the maximum sound absorption coefficient α _max is less than 50%, it is not desirable as a sound absorbing material.

The thickness _{t 2} of the plate-like member 2 is preferably set as appropriate in a range of less than 5mm as 0.5mm or more as described above. Furthermore diameter d ₂ of the through holes is preferably set as appropriate in a range of less than 400μm as 30μm or above.
In the sound-absorbing material of the present embodiment, the diameter d ₂ of the through hole, so the preferred range of the thickness t ₂ of the aperture ratio sigma ₂ and the plate-shaped member is varied, below, the diameter d ₂ of the through _hole, the aperture ratio sigma ₂ The relationship between the thickness t ₂ of the plate-like member will be described while dividing the range of the diameter d ₂ of the through hole.

(If the diameter _{d 2} of the through hole is 30 to 50 [mu] m)
When the diameter d _{2 of the} through hole is 30 to 50 μm, it is preferable to set the thickness t ₂ of the plate-like member in the range of 0.5 to 2 mm. Further, in order to ensure a maximum sound absorption coefficient α _max of 50% or more in the range of the diameter d ₂ and the thickness t ₂ , the through hole opening ratio σ ₂ may be set to 5.0% or more. In order to secure the maximum sound absorption coefficient α _max of 70% or more, the aperture ratio σ ₂ may be set to 8.0% or more. Furthermore, in order to ensure the maximum sound absorption coefficient α _max of 90% or more, the aperture ratio σ ₂ may be set to 15% or more. If the aperture ratio σ ₂ is out of these ranges, the desired maximum sound absorption coefficient α _max cannot be obtained. In addition, when the diameter d ₂ is 30 to 50 μm, it is preferable that the upper limit of the aperture ratio σ ₂ is 80% or less from the viewpoint of preventing rainwater from entering during rain and improving the mechanical strength of the sound absorbing material. .

(If the diameter _{d 2} of the through hole is 50 to 80 [mu] m)
When the diameter d _{2 of the} through hole is 50 to 80 μm, it is preferable to set the thickness t ₂ of the plate-like member in the range of 1 mm to ₂ mm. Further, in order to ensure a maximum sound absorption coefficient α _max of 50% or more in the range of the diameter d ₂ and the thickness t ₂ , the through hole opening ratio σ ₂ may be set to at least 4.0% or more. In order to secure a maximum sound absorption coefficient α _max of 70% or more, the aperture ratio σ ₂ may be set to at least 6.0% or more. Furthermore, in order to secure the maximum sound absorption coefficient α _max of 90% or more, the aperture ratio σ ₂ may be set to at least 11% or more.
Further, if the diameter _{d 2} of 50~80μm may set the thickness _{t 2} of the plate-like member in a range of 0.5 to 1 mm. In this case, in order to ensure the maximum sound absorption coefficient α _max of 50% or more, the aperture ratio σ ₂ of the through hole may be set to 2.0% or more, and in order to ensure the maximum sound absorption coefficient α _max of 70% or more. Therefore, the aperture ratio σ ₂ may be set to 3.0% or more, and the aperture ratio σ ₂ may be set to 6% or more in order to ensure the maximum sound absorption coefficient α _max of 90% or more.
If the aperture ratio σ ₂ is out of these ranges, the desired maximum sound absorption coefficient α _max cannot be obtained. When the diameter d ₂ is 50 to 80 μm, it is preferable that the upper limit of the aperture ratio σ ₂ is 80% or less from the viewpoint of preventing rainwater from entering during rain and improving the mechanical strength of the sound absorbing material. .

(If the diameter _{d 2} of the through hole is 80 to 100)
When the diameter d _{2 of the} through hole is 80 to 100 μm, it is preferable to set the thickness t ₂ of the plate-like member in the range of ₂ mm to 5 mm. Further, in order to ensure a maximum sound absorption coefficient α _max of 50% or more in the range of the diameter d ₂ and the thickness t ₂ , the through hole opening ratio σ ₂ may be at least 5.0% or more. In order to secure the maximum sound absorption coefficient α _max of 70% or more, the aperture ratio σ ₂ may be set to at least 10% or more. Furthermore, in order to ensure the maximum sound absorption coefficient α _max of 90% or more, the aperture ratio σ ₂ may be set to at least 15% or more.
Further, when the diameter d ₂ is 80 to 100 μm, the thickness t ₂ of the plate-like member may be set in a range of 0.5 to 2 mm. In this case, in order to ensure the maximum sound absorption coefficient α _max of 50% or more, the aperture ratio σ ₂ of the through hole may be set to 1.0% or more, and in order to ensure the maximum sound absorption coefficient α _max of 70% or more. Therefore, the aperture ratio σ ₂ may be set to 2.5% or more, and the aperture ratio σ ₂ may be set to 4.0% or more to secure the maximum sound absorption coefficient α _max of 90% or more.
If the aperture ratio σ ₂ is out of these ranges, the desired maximum sound absorption coefficient α _max cannot be obtained. When the diameter d ₂ is 80 to 100 μm, it is preferable that the upper limit of the aperture ratio σ ₂ is 80% or less from the viewpoint of preventing rainwater from entering during rain and improving the mechanical strength of the sound absorbing material. .

(If the diameter _{d 2} of the through holes of 100-200 [mu] m)
When the diameter _{d 2} of the through hole is 100~200μm, it is preferable to set the thickness _{t 2} of the plate-like member in a range of 2 mm to 5 mm. Further, in order to ensure a maximum sound absorption coefficient α _max of 50% or more in the range of the diameter d ₂ and the thickness t ₂ , the through hole opening ratio σ ₂ may be at least 1.0% or more. In order to secure the maximum sound absorption coefficient α _max of 70% or more, the aperture ratio σ ₂ may be set to at least 3.0% or more. Furthermore, in order to secure the maximum sound absorption coefficient α _max of 90% or more, the aperture ratio σ ₂ may be set to at least 4.0% or more.
Furthermore, the diameter _{d 2} of the through hole in the case of 100~200μm may set the thickness _{t 2} of the plate-like member in a range of 0.5 to 2 mm. In this case, in order to ensure the maximum sound absorption coefficient α _max of 50% or more, the opening ratio σ ₂ of the through hole may be set to 0.3% or more, and in order to ensure the maximum sound absorption coefficient α _max of 70% or more. The aperture ratio σ ₂ may be set to 0.5 to 90%, and the aperture ratio σ ₂ may be set to 1.0 to 60% in order to secure the maximum sound absorption coefficient α _max of 90% or more.
If the aperture ratio σ ₂ is out of these ranges, the desired maximum sound absorption coefficient α _max cannot be obtained. Further, when the diameter d ₂ is 100 to 200 μm, setting the upper limit of the aperture ratio σ ₂ to at least 80% can prevent the intrusion of rainwater during rain and improve the mechanical strength of the sound absorbing material. preferable.

(If the diameter _{d 2} of the through hole is 200 to 400)
When the diameter d _{2 of the} through hole is 200 to 400 μm, it is preferable to set the thickness t ₂ of the plate-like member in the range of 0.5 to 5 mm. Further, in order to ensure a maximum sound absorption coefficient α _max of 50% or more in the range of the diameter d ₂ and the thickness t ₂ , the through hole opening ratio σ ₂ may be set to 0.2 to 70%. In order to secure the maximum sound absorption coefficient α _max of 70% or more, the aperture ratio σ ₂ may be set to 0.3 to 60%. Furthermore, in order to ensure the maximum sound absorption coefficient α _max of 90% or more, the aperture ratio σ ₂ may be set to 0.5 to 30%. If the aperture ratio σ ₂ is out of these ranges, the desired maximum sound absorption coefficient α _max cannot be obtained.

  Next, one surface of the plate-like member is subjected to water repellent treatment as described above. For water-repellent treatment, a method of applying fluorine resin fine particles such as polytetrafluoroethylene together with a fluorine-based varnish, and an electrolytic plating bath in which fluorine resin fine particles such as polytetrafluoroethylene are dispersed are prepared. And the method of performing electroplating with respect to one surface of a plate-shaped member can be illustrated. Also, applying a general water repellent spray or the like is effective. In any case, fluororesin fine particles are fixed to one surface of the plate-like member. The contact angle of water with respect to one surface after the water repellent treatment is preferably 100 ° or more, more preferably 120 ° or more, and most preferably 150 ° or more. The water repellency improves as the fixing amount increases. However, since the light-transmitting property of the sound-absorbing material decreases when the fixing amount becomes excessive, it is desirable to control the fixing amount within a range that does not impair the light-transmitting property.

As in the first example, the sound absorbing material is disposed so that the other surface of the plate member faces the indoor sound source position, and one surface of the plate member subjected to the water repellent treatment is outdoors. It is desirable to arrange so that it faces. The surface of the sound absorbing material opposite to the sound source position is in contact with the air layer, and the air layer and the through hole of the sound absorbing material communicate with each other to form a so-called Helmholtz resonator, thereby obtaining sound absorbing performance.
Since the sound absorption performance of the Helmholtz resonator is determined by the thickness t ₂ (length of the through hole) of the plate-like member, the diameter d _{2 of} the through holes, the interval between the through holes, the opening ratio σ _{2 of the} through holes, etc. What is necessary is just to set suitably in the optimal range mentioned above so that the maximum sound absorption rate may be obtained according to acoustic characteristics, such as the frequency of the sound to absorb sound.

Next, the manufacturing method of the sound absorbing material of this example will be described.
The sound-absorbing material of this example is obtained by bringing a mask having a predetermined pattern into close contact with a photosensitive glass serving as a plate-like member, exposing the photosensitive glass by irradiating ultraviolet rays from the mask, and exposing the exposed portion in the photosensitive glass. A latent image forming process for forming a latent image corresponding to the above, a crystallization process for crystallizing an exposed portion by heat-treating the processed glass after the latent image forming process, an etching process for the processed glass after the crystallization process, and a crystal It can be manufactured through a dissolution process in which the exposed exposed portion is dissolved and removed so as to penetrate the front and back surfaces and a water repellent treatment process. Moreover, you may add the process of grind | polishing process glass after a melt | dissolution process.
Since the latent image forming step, the crystallization step, the dissolving step, and the polishing step are the same as in the first example, a detailed description thereof will be omitted, and the water repellent treatment will be described here.

(Water repellent treatment)
In the water repellent process, a water repellent process is performed on the treated glass after the melting process or the polishing process. In this example, the water repellent treatment can be performed by one of the following two methods.
In the first method, first, a fluorine-based paint in which fine particles made of a fluorine resin such as polytetrafluoroethylene are dispersed in a fluorine-based varnish is prepared. As such a fluorine-based paint, for example, HIREC 100 manufactured by Toei Electric Industry Co., Ltd. can be used. The fine particles made of a fluororesin in the fluorine-based paint preferably have an average particle size of about 4 μm.
Next, the prepared fluorine-based paint is applied to one surface of the treated glass by a known application means. After application, dry the fluorine-based paint completely. As a result, the fluororesin fine particles are fixed to one surface of the treated glass, and the water repellent treatment is performed. The contact angle of water on one surface of the glass treated by this water repellent treatment is about 120 °.

  In the second method of the water repellent process, first, a plating base solution is prepared. The plating base solution is prepared, for example, by dissolving 350 g of nickel sulfamate, 45 g of nickel chloride, and 40 g of boric acid with 1 L of water. The temperature of the plating base solution is about 45 ° C. Next, 55 g of fine powder having an average particle diameter of about 4 μm made of a fluororesin such as polytetrafluoroethylene is introduced and dispersed in 25 ml of water to which a surfactant is added at a concentration of 1 g / 100 ml. An electric field bath is prepared by mixing the previously prepared plating base solution with this dispersion. The temperature of the electric field bath is about 45 ° C. As the surfactant for the dispersion, for example, a cationic perfluoroalkylammonium salt (trade name: Megafac F-150 (Dainippon Ink Chemical Co., Ltd.)) can be used.

Next, electrolytic plating is performed on the treated glass using this electric field bath. When performing electroplating, it is desirable to set the current density to about 3 to 5 A / cm ² .
By the above procedure, the fluororesin fine particles are fixed to one surface of the treated glass, and the water repellent treatment is performed. The contact angle of water on one surface of the glass treated by this water repellent treatment is about 150 °.
Further, as a water repellent treatment, a general water repellent spray may be sprayed, and the contact angle of water in this case is about 100 °.
The sound absorbing material of this example is obtained through the above steps.

As described above, according to the sound-absorbing material of this example, the water-repellent treatment is performed on one surface side, so the diameter of the through hole is in the range of 30 to 400 μm and is relatively large, but the sound-absorbing material is caused by rain or the like. Even when rainwater pours into the material, there is no possibility of rainwater infiltrating from one side of the plate member to the other side due to the effect of the water repellent treatment.
It is also possible to ventilate through the through hole.
Furthermore, by appropriately setting the aperture ratio σ ₂ of the through hole and the thickness t ₂ of the plate-like member within the above ranges, a maximum sound absorption coefficient α _max of at least 50% is secured, and at the same time, intrusion of rainwater or the like is prevented. And ventilation performance is ensured. Moreover, it becomes what was excellent in the daylighting property by comprising a plate-shaped member from a translucent material.

"Sound Absorbing Material Panel"
Next, a sound absorbing panel including the above sound absorbing material will be described with reference to FIGS.
(First example of sound absorbing panel)
FIG. 3 is a schematic cross-sectional view of a first example of a sound absorbing panel.
The sound absorbing panel 10 shown in FIG. 3 has a sound absorbing material 11 (one sound absorbing material) made of a plate-like member provided with a plurality of through holes and a sound absorbing material 1 (the other sound absorbing material) of the first example as a predetermined. Are arranged so as to face each other with an interval of. By arranging the sound absorbing materials 1 and 11 apart from each other, an air layer 12 is formed between the sound absorbing materials 1 and 11. By providing the air layer 12 between the sound absorbing materials 1 and 11, the through holes of the sound absorbing materials 1 and 11 and the air layer 12 are communicated with each other, thereby forming a so-called Helmholtz resonator. Thereby, a sound absorption characteristic can be improved significantly.
The distance m ₁ between the sound absorbing materials 1 and 11, in other words, the thickness of the air layer 12 is preferably in the range of 5 mm to 1000 mm, and more preferably in the range of 50 mm to 500 mm. If the thickness of the air layer 12 is out of this range, good sound absorption characteristics cannot be obtained.

  Although the diameter of the through-hole provided in one sound-absorbing material 11 is not specifically limited, As an example, it sets to the same grade (30 micrometers or less or 30-400 micrometers) as the diameter of the through-hole in the above-mentioned 1st or 2nd sound-absorbing material. You may do it. Moreover, what is necessary is just to set similarly to the case of the above-mentioned 1st or 2nd sound-absorbing material according to the diameter of a through-hole about the aperture ratio of a through-hole, and the plate | board thickness of a sound-absorbing material. Further, the material of one sound absorbing material 11 may be composed of a light-transmitting material such as photosensitive glass, like the other sound absorbing material.

When the sound absorbing panel 10 of this example is installed as a wall material for a hall or an outerium, it is desirable to install the other sound absorbing material 1 on the outdoor side and one sound absorbing material 11 on the indoor side.
The sound absorbing material 1 installed on the outdoor side is provided with a plurality of through holes having a diameter of 30 μm or less, and the diameter is sufficiently small to prevent water from entering the through holes. Even if it is poured down, there is no possibility that rainwater will enter the indoor side through the through hole. In addition, since the sound absorbing materials 1 and 11 are provided with through holes, ventilation can be ensured. Furthermore, since both the sound-absorbing materials 1 and 11 are made of a translucent material, it is possible to secure daylighting.

(Second example of sound absorbing panel)
FIG. 4 is a schematic cross-sectional view of a second example of the sound absorbing panel.
The sound absorbing panel 20 shown in FIG. 4 includes a sound absorbing material 11 (one sound absorbing material) made of a plate-like member provided with a plurality of through holes and a sound absorbing material 21 (the other sound absorbing material) of the second example. Are arranged so as to face each other with an interval of. By arranging the sound absorbing materials 11 and 21 apart from each other, an air layer 22 is formed between the sound absorbing materials 11 and 21. By providing the air layer 22 between the sound absorbing materials 11 and 21, the through holes of the sound absorbing materials 11 and 21 and the air layer 22 are communicated with each other, thereby forming a so-called Helmholtz resonator. Thereby, a sound absorption characteristic can be improved significantly.
The distance m ₂ between the sound absorbing materials 11 and 21, in other words, the thickness of the air layer 22 is preferably in the range of 5 mm to 1000 mm, and more preferably in the range of 50 mm to 500 mm. If the thickness of the air layer 22 is out of this range, good sound absorption characteristics cannot be obtained.

  The other sound absorbing material 21 is subjected to water repellent treatment on one surface 21a side, and a fluororesin 21b is fixed thereto. When the other sound absorbing material 21 is disposed opposite to the one sound absorbing material 11, it is preferable that the one surface 21a subjected to the water repellent treatment is disposed so as to face the side opposite to the one sound absorbing material 11.

  Further, as in the first example of the sound absorbing panel, the one sound absorbing material 11 is not particularly limited in the diameter of the through hole, and as an example, the diameter of the through hole in the first or second sound absorbing material described above. And the same degree (30 μm or less or 30 to 400 μm). Moreover, what is necessary is just to set similarly to the case of the above-mentioned 1st or 2nd sound-absorbing material also about the aperture ratio of a through-hole, and the plate | board thickness of a sound-absorbing material according to the diameter of a through-hole. The material may be made of a light-transmitting material such as photosensitive glass as with the other sound absorbing material 21.

When the sound absorbing panel 20 of this example is installed as a wall material for a hall or an outlium, it is desirable to install the other sound absorbing material 21 on the outdoor side and install the one sound absorbing material 11 on the indoor side. By installing in this way, the other sound absorbing material 21 is installed in a state where the one surface 21a subjected to the water repellent treatment faces the outdoors.
Since the sound absorbing material 21 installed on the outdoor side has a water repellent treatment on one surface 21a, the diameter of the through-hole is in the range of 30 to 400 μm and is relatively large, but water is repelled by the effect of the water repellent treatment. Since it is difficult to enter the through-hole, there is no possibility that rainwater enters the indoor side through the through-hole even when rainwater is poured onto the sound absorbing material 21 due to rain or the like. In addition, since the sound absorbing materials 11 and 21 are provided with through holes, ventilation can be ensured. Furthermore, since both the sound absorbing materials 11 and 21 are made of a translucent material, it is possible to secure daylighting.

(Third example of sound absorbing panel)
In FIG. 5, the 3rd example of a sound absorption panel is shown with a cross-sectional schematic diagram.
The sound absorbing panel 30 shown in FIG. 5 is configured by disposing a non-porous plate 31 made of a translucent material and the sound absorbing material 1 of the first example so as to face each other at a predetermined interval. . By arranging the non-porous plate 31 and the sound absorbing material 1 apart from each other, an air layer 32 is formed between the non-porous plate 31 and the sound absorbing material 1. By providing the air layer 32, the through-hole of the sound absorbing material 1 and the air layer 32 are communicated with each other, thereby forming a so-called Helmholtz resonator. Thereby, a sound absorption characteristic can be improved significantly.
The distance m ₃ between the non-porous plate 31 and the sound absorbing material 1, in other words, the thickness of the air layer 32 is preferably in the range of 5 mm to 1000 mm, and more preferably in the range of 50 mm to 500 mm. If the thickness of the air layer 32 is out of this range, good sound absorption characteristics cannot be obtained.

The plate-like non-perforated plate 31 made of a light-transmitting material is not particularly limited as long as it is a plate-like light-transmitting member having no through-hole, and for example, plate glass or the like is preferable. It is desirable that an opening / closing mechanism is attached to the non-perforated plate 31. As the opening / closing mechanism, for example, a plate glass (non-porous plate) may be fitted into a window frame material such as an aluminum sash to form a window material with an opening / closing mechanism.
In addition, when the sound absorbing panel 30 of this example is installed as a wall material for a hall or an outerium, it is desirable to install the non-perforated plate 31 on the outdoor side and the sound absorbing material 1 on the indoor side.

When the window member made of the non-perforated plate 31 is opened by the opening / closing mechanism described above, the outside air is introduced to the sound absorbing material 1, and the sound absorbing material 1 is provided with a plurality of through holes having a diameter of 30 μm or less as described above. Therefore, outside air is introduced into the indoor side through the through hole. Thus, the sound absorption panel 30 of this example can ensure ventilation.
Further, the sound absorbing material 1 installed on the indoor side is provided with a plurality of through holes having a diameter of 30 μm or less, and the diameter of the through holes is sufficiently small to prevent water from entering. Therefore, for example, in order to ensure ventilation, even when rainwater is poured into the sound absorbing material 1 due to rain or the like in a state where the window material made of the non-perforated plate 31 is opened by the above-described opening and closing mechanism, it passes through the through hole. There is no risk of rainwater entering the indoor side.
Furthermore, since both the non-perforated plate 31 and the sound absorbing material 1 are made of a translucent material, it is possible to secure daylighting.

(Fourth example of sound absorbing panel)
In FIG. 6, the 4th example of a sound absorption panel is shown with a cross-sectional schematic diagram.
The sound absorbing panel 40 shown in FIG. 6 is configured by disposing a non-porous plate 31 made of a translucent material and the sound absorbing material 21 of the second example so as to face each other with a predetermined interval. . By arranging the non-porous plate 31 and the sound absorbing material 21 apart from each other, an air layer 41 is formed between the non-porous plate 31 and the sound absorbing material 21. By providing the air layer 41, the through-hole of the sound absorbing material 21 and the air layer 41 are communicated with each other, thereby forming a so-called Helmholtz resonator. Thereby, a sound absorption characteristic can be improved significantly.
The distance m ₄ between the non-porous plate 31 and the sound absorbing material 1, in other words, the thickness of the air layer 41 is preferably in the range of 5 mm to 1000 mm, and more preferably in the range of 50 mm to 500 mm. If the thickness of the air layer 41 is out of this range, good sound absorption characteristics cannot be obtained.

The plate-like non-porous plate 31 made of a light-transmitting material is not particularly limited as long as it is a plate-like light-transmitting member having no through holes, as in the third example of the sound absorbing panel. Is good. It is desirable that an opening / closing mechanism similar to that in the third example is attached to the non-perforated plate 31.
Moreover, when installing the sound absorbing panel 40 of this example as a wall material of a hall | hole or an outlium, it is desirable to install the non-perforated plate 31 on the outdoor side and install the sound absorbing material 21 on the indoor side. Further, when the sound absorbing material 21 is disposed with respect to the non-perforated plate 31, it is preferable that the one surface 21 a on which the water-repellent treatment of the sound absorbing material 21 is performed faces the outdoor side (non-perforated plate side).

When the window material comprising the non-perforated plate 31 is opened by the opening / closing mechanism described above, outside air is introduced to the sound absorbing material 21, and the sound absorbing material 21 is provided with a plurality of through holes having a diameter of 30 μm to 400 μm as described above. Therefore, outside air is introduced into the indoor side through the through hole. In this way, the sound absorbing panel 40 of this example can ensure ventilation.
In addition, the sound absorbing material 21 installed on the indoor side has a water repellent treatment on one surface 21a, so that the diameter of the through hole is in the range of 30 to 400 μm and is relatively large. It is difficult for water to enter the through hole due to the effect of water treatment. Therefore, for example, in order to ensure ventilation, even when rainwater is poured on the sound absorbing material 21 due to rain or the like in a state where the window member made of the non-perforated plate 31 is opened by the above-described opening and closing mechanism, it passes through the through hole. There is no risk of rainwater entering the indoor side.
Furthermore, since both the non-porous plate 31 and the sound absorbing material 21 are made of a translucent material, it is possible to secure daylighting.

“Experimental example 1 (sound absorption characteristics in the case of a through hole having a diameter of 30 μm)”
A mask having a predetermined pattern was brought into close contact with a transparent photosensitive glass substrate, and the photosensitive glass was exposed by irradiating ultraviolet rays from the mask to form a latent image corresponding to the exposed portion in the photosensitive glass. Next, the processed glass after the latent image formation was heat-treated at 600 ° C. for 1 hour to crystallize the exposed portion. Next, the treated glass after crystallization was etched to dissolve and remove the crystallized exposed portions and penetrated the front and back surfaces to form through holes. In this way, various sound absorbing materials were manufactured.

  The thickness of the sound absorbing material was 0.5 to 5 mm, the diameter of the through holes was 30 μm, and the through holes were arranged in a staggered pattern with a relative angle of 60 °. The pitch of the through holes was 35 to 150 μm.

With respect to the obtained various sound absorbing materials, the normal incident sound absorption characteristics were measured, and the maximum sound absorption coefficient α _max was measured. The results are shown in Table 1 and FIG. Table 1 also shows the aperture ratio corresponding to the pitch of the through holes. FIG. 7 shows the relationship between the aperture ratio and the maximum sound absorption coefficient α _max .

As shown in Table 1 and FIG. 7, when the diameter of the through hole is 30 μm, the maximum sound absorption coefficient α _max tends to increase as the aperture ratio increases for any sound absorbing material of any thickness. Recognize.

Further, as shown in Table 1, when the plate thickness is 0.5 mm, the aperture ratio should be 15% or more in order to ensure the maximum sound absorption coefficient α _max of 50% or more, and the maximum sound absorption coefficient of 70% or more. if the aperture ratio is 20% or more to ensure the alpha _max well, it can be seen that the aperture ratio to ensure maximum sound absorption coefficient alpha _max of 90% or more may be 35% or more.

Next, when the plate thickness is 0.7 mm, in order to ensure the maximum sound absorption coefficient α _max of 50% or more, the aperture ratio may be set to 20% or more, and the maximum sound absorption coefficient α _max of 70% or more is ensured. It is understood that the aperture ratio should be 32% or more, and the aperture ratio should be 66% or more to ensure the maximum sound absorption coefficient α _max of 90% or more.

Next, in the plate thickness of 1 mm, to ensure maximum sound absorption coefficient alpha _max of 50% or more may be the aperture ratio over 32%, to ensure maximum sound absorption coefficient alpha _max of 70% or more It can be seen that the aperture ratio should be 50% or more.
Next, it can be seen that when the plate thickness is 2 mm, the aperture ratio should be 66% or more in order to secure the maximum sound absorption coefficient α _max of 50% or more.

  Further, as shown in Table 1, it can be seen that when the plate thickness exceeds 2 mm, a maximum sound absorption rate of 50% or more cannot be obtained.

“Experimental example 2 (sound absorption characteristics in the case of a through hole having a diameter of 50 μm)”
The thickness of the sound absorbing material is 0.5 to 5 mm, the diameter of the through holes is 50 μm, the through holes are arranged in a staggered pattern with a relative angle of 60 °, and the pitch of the through holes is 60 to 250 μm. Various sound absorbing materials were manufactured in the same manner as in Experimental Example 1.

With respect to the obtained various sound absorbing materials, the normal incident sound absorption characteristics were measured, and the maximum sound absorption coefficient α _max was measured. The results are shown in Table 2 and FIG. Table 2 also shows the aperture ratio corresponding to the pitch of the through holes. FIG. 8 shows the relationship between the aperture ratio and the maximum sound absorption coefficient α _max .

As shown in Table 2 and FIG. 8, when the diameter of the through hole is 50 μm, the maximum sound absorption coefficient α _max may peak as the aperture ratio increases, such as the plate thickness of 0.5 mm. In other cases, the maximum sound absorption coefficient α _max tends to increase as the aperture ratio increases.

As shown in Table 2, when the plate thickness is 0.5 mm, the aperture ratio should be 5% or more to ensure the maximum sound absorption coefficient α _max of 50% or more, and the maximum sound absorption coefficient of 70% or more. if to ensure alpha _max is the numerical aperture more than 8.8% better, it can be seen that the aperture ratio to ensure maximum sound absorption coefficient alpha _max of 90% or more may be more than 15.7%.

Next, in the plate thickness of 1 mm, to ensure maximum sound absorption coefficient alpha _max of 50% or more may be the aperture ratio 10% or more, to ensure maximum sound absorption coefficient alpha _max of 70% or more It can be seen that the aperture ratio should be 17% or more, and the aperture ratio should be 29% or more to ensure the maximum sound absorption coefficient α _max of 90% or more.

Next, in the plate thickness of 2 mm, to ensure maximum sound absorption coefficient alpha _max of 50% or more may be the aperture ratio over 19%, to ensure maximum sound absorption coefficient alpha _max of 70% or more It can be seen that the aperture ratio should be 28% or higher, and the aperture ratio should be 62% or higher in order to secure the maximum sound absorption coefficient α _max of 90% or higher.
Next, it can be seen that when the plate thickness is 5 mm, the aperture ratio should be 62% or more in order to secure the maximum sound absorption coefficient α _max of 50% or more.

“Experimental example 3 (sound absorption characteristics in the case of a through hole with a diameter of 80 μm)”
The thickness of the sound absorbing material is 0.5 to 5 mm, the diameter of the through holes is 80 μm, the through holes are arranged in a staggered pattern with a relative angle of 60 °, and the pitch of the through holes is 95 to 700 μm. Various sound absorbing materials were manufactured in the same manner as in Experimental Example 1.
With respect to the obtained various sound absorbing materials, the normal incident sound absorption characteristics were measured, and the maximum sound absorption coefficient α _max was measured. The results are shown in Table 3 and FIG.

As shown in Table 3 and FIG. 9, when the plate thickness is in the range of 0.5 to 1 mm, the maximum sound absorption rate α _max shows a peak as the aperture ratio increases, and thereafter the maximum sound absorption rate α _max tends to decrease. It is in. On the other hand, when the plate thickness is in the range of 2 to 5 mm, the maximum sound absorption coefficient α _max tends to increase as the aperture ratio increases.

As shown in Table 3, when the plate thickness is 0.5 mm, the aperture ratio should be 1.9 to 65% in order to ensure the maximum sound absorption coefficient α _max of 50% or more, and 70% or more. to ensure maximum sound absorption coefficient alpha _max may be an aperture ratio from 3 to 38%, that may be the aperture ratio to ensure maximum sound absorption coefficient alpha _max of 90% at 5% to 22% Recognize.

Next, in the plate thickness of 1 mm, to ensure maximum sound absorption coefficient alpha _max of 50% or more may be an aperture ratio than 3.8%, to ensure maximum sound absorption coefficient alpha _max of 70% It is understood that the aperture ratio should be 6% or more, and the aperture ratio should be 11 to 41% to ensure the maximum sound absorption coefficient α _max of 90% or more.

Next, in the plate thickness of 2 mm, to ensure maximum sound absorption coefficient alpha _max of 50% or more may be an aperture ratio than 8.5%, to ensure maximum sound absorption coefficient alpha _max of 70% It can be seen that the aperture ratio should be 14% or more, and the aperture ratio should be 23% or more to ensure the maximum sound absorption coefficient α _max of 90% or more.

Next, in the plate thickness of 5 mm, to ensure maximum sound absorption coefficient alpha _max of 50% or more may be an aperture ratio of 18% or more, to ensure maximum sound absorption coefficient alpha _max of 70% or more It can be seen that the aperture ratio should be 32% or more, and the aperture ratio should be 57% or more to ensure the maximum sound absorption coefficient α _max of 90% or more.

“Experimental example 4 (sound absorption characteristics in the case of a through hole having a diameter of 100 μm)”
The thickness of the sound absorbing material is 0.5 to 5 mm, the diameter of the through holes is 100 μm, the through holes are arranged in a staggered pattern with a relative angle of 60 °, and the pitch of the through holes is 120 to 2000 μm. Various sound absorbing materials were manufactured in the same manner as in Experimental Example 1.
With respect to the obtained various sound absorbing materials, the normal incident sound absorption characteristics were measured, and the maximum sound absorption coefficient α _max was measured. The results are shown in Table 4 and FIG.

As shown in Table 4 and FIG. 10, when the plate thickness is in the range of 0.5 to 2 m, the maximum sound absorption rate α _max shows a peak as the aperture ratio increases, and then the maximum sound absorption rate α _max tends to decrease. You can see that On the other hand, when the plate thickness is 5 mm, the maximum sound absorption rate α _max tends to increase as the aperture ratio increases.

As shown in Table 4, when the plate thickness is 0.5 mm, the aperture ratio should be 1.2 to 42% in order to ensure the maximum sound absorption coefficient α _max of 50% or more, and 70% or more. to ensure maximum sound absorption coefficient alpha _max may be an aperture ratio from 2.5 to 26%, to ensure maximum sound absorption coefficient alpha _max 90% or more if the aperture ratio from 3.7 to 14% I know it ’s good.
Next, in the plate thickness of 1 mm, to ensure maximum sound absorption coefficient alpha _max of 50% or more may be an aperture ratio than 1.2%, to ensure maximum sound absorption coefficient alpha _max of 70% It is understood that the aperture ratio should be 4 to 50% or more, and the aperture ratio should be 7.3 to 28% to ensure the maximum sound absorption coefficient α _max of 90% or more.

Next, in the plate thickness of 2 mm, to ensure maximum sound absorption coefficient alpha _max of 50% or more may be the aperture ratio 5% or more, to ensure maximum sound absorption coefficient alpha _max of 70% or more It can be seen that the aperture ratio should be 7.5% or more, and the aperture ratio should be 15 to 54% in order to ensure the maximum sound absorption coefficient α _max of 90% or more.
Next, in the plate thickness of 5 mm, to ensure more than 50% of the maximum sound absorption coefficient alpha _max it may be an aperture ratio than 12.1%, to ensure maximum sound absorption coefficient alpha _max of 70% It is understood that the aperture ratio should be 20% or more, and the aperture ratio should be 35% or more to ensure the maximum sound absorption coefficient α _max of 90% or more.

“Experimental example 5 (sound absorption characteristics in the case of a through hole having a diameter of 200 μm)”
The thickness of the sound absorbing material is 0.5 to 10 mm, the diameter of the through holes is 200 μm, the through holes are arranged in a staggered pattern with a relative angle of 60 °, and the pitch of the through holes is 230 to 4000 μm. Various sound absorbing materials were manufactured in the same manner as in Experimental Example 1.
With respect to the obtained various sound absorbing materials, the normal incident sound absorption characteristics were measured, and the maximum sound absorption coefficient α _max was measured. The results are shown in Table 5 and FIG.

As shown in Table 5 and FIG. 11, in any sound absorbing material having any thickness, the maximum sound absorption coefficient α _max shows a peak as the aperture ratio increases, and thereafter the maximum sound absorption coefficient α _max tends to decrease. I understand that.

Further, as shown in Table 5, when the plate thickness is 0.5 mm, the aperture ratio should be 0.2 to 11% to ensure the maximum sound absorption coefficient α _max of 50% or more, and 70% or more. to ensure maximum sound absorption coefficient alpha _max may be an aperture ratio from 0.4 to 6%, it may be be the aperture ratio to ensure maximum sound absorption coefficient alpha _max of 90% to 1-3% I understand.

Next, in the plate thickness of 1 mm, to ensure maximum sound absorption coefficient alpha _max of 50% or more may be an aperture ratio from 0.5 to 22%, ensuring maximum sound absorption coefficient alpha _max of 70% It can be seen that the aperture ratio should be 1 to 14%, and the aperture ratio should be 2 to 7% to ensure the maximum sound absorption coefficient α _max of 90% or more.
Next, in the plate thickness of 2 mm, the aperture ratio to ensure maximum sound absorption coefficient alpha _max of 50% or more may be in the 1-42%, to ensure maximum sound absorption coefficient alpha _max of 70% It is understood that the aperture ratio should be 3 to 20%, and the aperture ratio should be 3% to 13% to ensure the maximum sound absorption coefficient α _max of 90% or more.

Next, in the plate thickness of 5 mm, to ensure maximum sound absorption coefficient alpha _max of 50% or more may be the aperture ratio equal to 2 percent, to ensure maximum sound absorption coefficient alpha _max of 70% or more It can be seen that the aperture ratio should be 5 to 65%, and the aperture ratio should be 10% to 35% to ensure the maximum sound absorption coefficient α _max of 90% or more.
Next, in the plate thickness of 10 mm, to ensure maximum sound absorption coefficient alpha _max of 50% or more may be an aperture ratio than 6%, to ensure maximum sound absorption coefficient alpha _max of 70% or more It can be seen that the aperture ratio should be 11% or more, and the aperture ratio should be 18% or more to ensure the maximum sound absorption coefficient α _max of 90% or more.

“Experimental example 6 (sound absorption characteristics in the case of a through hole having a diameter of 400 μm)”
Experimental example except that the thickness of the sound absorbing material is 1 to 10 mm, the diameter of the through holes is 400 μm, the through holes are arranged in a staggered pattern with a relative angle of 60 °, and the pitch of the through holes is 500 to 10,000 μm. In the same manner as in Example 1, various sound absorbing materials were produced.
With respect to the obtained various sound absorbing materials, the normal incident sound absorption characteristics were measured, and the maximum sound absorption coefficient α _max was measured. The results are shown in Table 6 and FIG.

As shown in Table 6 and FIG. 12, in any sound absorbing material of any thickness, the maximum sound absorption coefficient α _max shows a peak as the aperture ratio increases, and thereafter the maximum sound absorption coefficient α _max tends to decrease. I understand that.

In addition, as shown in Table 6, in any sound absorbing material of any thickness, the maximum sound absorption coefficient α _max peaks as the aperture ratio increases, and thereafter the maximum sound absorption coefficient α _max tends to decrease. Recognize.

Next, in the plate thickness of 1 mm, to ensure maximum sound absorption coefficient alpha _max of 50% or more may be an aperture ratio from 0.1 to 6%, ensure maximum sound absorption coefficient alpha _max of 70% It can be seen that the aperture ratio should be 0.2-3%, and the aperture ratio should be 0.5-2% to ensure a maximum sound absorption coefficient α _max of 90% or more.
Next, in the plate thickness of 2 mm, to ensure maximum sound absorption coefficient alpha _max of 50% or more may be an aperture ratio from 0.3 to 11.6%, 70% or more of the maximum sound absorption coefficient alpha _max It can be seen that the aperture ratio should be 0.4 to 7% in order to ensure the above, and the aperture ratio should be 1 to 4% in order to ensure the maximum sound absorption coefficient α _max of 90% or more.

Next, in the plate thickness of 5 mm, to ensure maximum sound absorption coefficient alpha _max of 50% or more may be the aperture ratio over 0.8 to 29%, a maximum sound absorption coefficient alpha _max of 70% It can be seen that the aperture ratio should be 1.5 to 15% to ensure, and the aperture ratio should be 2.5% to 9% to ensure the maximum sound absorption coefficient α _max of 90% or more.
Next, in the plate thickness of 10 mm, to ensure maximum sound absorption coefficient alpha _max of 50% or more may be the aperture ratio over 1.5 to 56%, a maximum sound absorption coefficient alpha _max of 70% It can be seen that the aperture ratio should be 3 to 30% to ensure, and the aperture ratio should be 5 to 18% to ensure the maximum sound absorption coefficient α _max of 90% or more.

"Experimental example 7 (evaluation of sound absorption characteristics)"
The thickness of the sound absorbing material is 1 mm, the diameter of the through holes is 70 μm, the through holes are arranged in a staggered pattern with a relative angle of 60 °, the pitch of the through holes is 120 μm, and the aperture ratio is 40%. Produced the sound absorbing material of Experimental Example 7 in the same manner as Experimental Example 1.

Next, the normal incident sound absorption characteristics of the sound absorbing material of Experimental Example 7 were measured by the transfer function method (ISO 10534-2 compliant). Specifically, the sound absorbing material of Experimental Example 7 was disposed at one end of a hollow cylindrical acoustic tube having a length of 400 mm and an inner diameter of 40 mm, and the back air layer was 200 mm. The surface of the back air layer opposite to the sound absorbing material was a rigid body. A speaker is disposed at the other end of the acoustic tube. Further, two microphones were installed at a predetermined interval between one end and the other end of the acoustic tube. Each speaker and microphone was connected to a computing device for measurement. In this way, a measurement apparatus for normal incident sound absorption characteristics by the transfer function method (based on ISO 10534-2) was configured.
Then, a sound having a certain band from the speaker was radiated into the acoustic tube, a transmission function between two microphones provided in the tube was measured, and a normal incidence sound absorption characteristic ratio was calculated based on this transmission function.
The measurement result of the normal incidence sound absorption coefficient is shown in FIG. FIG. 13 shows the maximum sound absorption disclosed in the literature (Dah-you Maa, “Potential of microperforated panel absorber”, J. Account. Soc. Am., Vol. 104, No. 5, November, 1998). The calculated value of the normal incidence sound absorption coefficient calculated according to the rate calculation method is also shown.

  As shown in FIG. 13, the measured values are in good agreement with the calculated values, indicating that excellent sound absorption characteristics are obtained.

"Experimental Examples 8 and 9 (Evaluation of sound absorption characteristics)"
The thickness of the sound absorbing material is 0.5 mm, the diameter of the through holes is 30 μm, the through holes are arranged in a staggered pattern with a relative angle of 60 °, the pitch of the through holes is 45 μm, and the aperture ratio is 40%. It was assumed that the sound absorbing material of Experimental Example 8 was manufactured in the same manner as Experimental Example 1 except that.
The plate thickness of the sound absorbing material is 5 mm, the diameter of the through holes is 400 μm, the through holes are arranged in a staggered pattern with a relative angle of 60 °, the pitch of the through holes is 1.2 mm, and the aperture ratio is 10 It was assumed that the sound-absorbing material of Experimental Example 9 was manufactured in the same manner as Experimental Example 1 except that the percentage was changed to%.

  Then, in the same manner as in Experimental Example 7, it was assumed that the normal incident sound absorption coefficient of each of the above sound absorbing materials was measured. 14 and 15 show the calculation results of the relationship between the normal incident sound absorption coefficient and the frequency of each sound absorbing panel. 14 and 15 are disclosed in the literature (Dah-you Maa, “Potential of microperforated panel absorber”, J. Account. Soc. Am., Vol. 104, No. 5, November, 1998). It is calculated according to the calculation method of the maximum sound absorption coefficient.

As shown in FIG. 14, the sound absorbing material of Experimental Example 8 has a normal incident sound absorption coefficient (maximum sound absorption coefficient) of about 0.89, indicating that there is a possibility of exhibiting good sound absorption characteristics. Further, since the diameter of the through hole is 30 μm, it is considered that intrusion of rainwater or the like can be prevented without water repellent treatment.
Next, as shown in FIG. 15, the sound absorbing material of Experimental Example 9 has a normal incident sound absorption coefficient (maximum sound absorption coefficient) of about 0.87, which indicates that there is a possibility of exhibiting good sound absorption characteristics. In addition, since the diameter of the through hole is 400 μm, rainwater or the like may enter, but it is considered that rainwater or the like can be prevented by performing water repellent treatment on one surface of the sound absorbing material.

“Experimental Examples 10 to 13 (Evaluation of Sound Absorption Characteristics)”
(Experimental example 10)
The thickness of the sound absorbing material is 0.5 mm, the diameter of the through holes is 30 μm, the through holes are arranged in a staggered pattern with a relative angle of 60 °, the pitch of the through holes is 45 μm, and the aperture ratio is 40%. Except that, two sound absorbing materials were produced in the same manner as in Experimental Example 1.
Next, the sound absorbing panel of Experimental Example 10 was manufactured by arranging the two sound absorbing materials obtained so as to face each other and providing a 200 mm thick air layer between the sound absorbing materials.

(Experimental example 11)
The plate thickness of the sound absorbing material is 5 mm, the diameter of the through holes is 400 μm, the through holes are arranged in a staggered pattern with a relative angle of 60 °, the pitch of the through holes is 1.2 mm, and the aperture ratio is 10 Two sound absorbing materials were produced in the same manner as in Experimental Example 1 except that the percentage was changed to%.
Next, the sound absorbing panel of Experimental Example 11 was manufactured by disposing the two sound absorbing materials obtained so as to face each other and providing an air layer having a thickness of 200 mm between the sound absorbing materials.

(Experimental example 12)
The plate thickness of the sound absorbing material is 5 mm, the diameter of the through holes is 400 μm, the through holes are arranged in a staggered pattern with a relative angle of 60 °, the pitch of the through holes is 1.2 mm, and the aperture ratio is 10 The sound-absorbing material on the sound source side was manufactured in the same manner as in Experimental Example 1 except that the percentage was changed to%.
The plate thickness of the sound absorbing material is 0.5 mm, the diameter of the through holes is 30 μm, the through holes are arranged in a staggered pattern with a relative angle of 60 °, the pitch of the through holes is 45 μm, and the aperture ratio is 40 The sound absorbing material on the outdoor side was produced in the same manner as in Experimental Example 1 except that the percentage was changed to%.
The sound-absorbing material on the sound source side and the sound-absorbing material on the outdoor side are arranged to face each other through a 200 mm air layer. Thus, the sound absorbing panel of Experimental Example 12 was manufactured.

(Experimental example 13)
The plate thickness of the sound absorbing material is 5 mm, the diameter of the through holes is 400 μm, the through holes are arranged in a staggered pattern with a relative angle of 60 °, the pitch of the through holes is 1.2 mm, and the aperture ratio is 10 The sound-absorbing material on the sound source side was manufactured in the same manner as in Experimental Example 1 except that the percentage was changed to%.
The plate thickness of the sound absorbing material is 0.5 mm, the diameter of the through holes is 30 μm, the through holes are arranged in a staggered pattern with a relative angle of 60 °, the pitch of the through holes is 0.1 mm, and the aperture ratio The sound absorbing material on the outdoor side was produced in the same manner as in Experimental Example 1 except that the content was 8%.
The sound-absorbing material on the sound source side and the sound-absorbing material on the outdoor side are arranged to face each other through a 200 mm air layer. Thus, the sound absorbing panel of Experimental Example 13 was manufactured.

  In the same manner as in Experimental Example 7, the normal incident sound absorption coefficient of each of the sound absorbing panels of Experimental Examples 10 to 13 was measured. The relationship between the normal incident sound absorption coefficient and the frequency of each sound absorbing panel is shown in FIGS.

As shown in FIG. 16, the sound absorption panel of Experimental Example 10 has a normal incident sound absorption coefficient (maximum sound absorption coefficient) of about 0.95, which indicates that the sound absorption characteristics are good. Further, since the diameter of the through hole is 30 μm, it is considered that intrusion of rainwater or the like can be prevented without water repellent treatment.
Next, as shown in FIG. 17, the sound absorption panel of Experimental Example 11 has a normal incident sound absorption coefficient (maximum sound absorption coefficient) of about 0.87, which indicates that the sound absorption characteristics are good. In addition, since the diameter of the through hole is 400 μm, rainwater or the like may enter, but it is considered that rainwater or the like can be prevented by performing water repellent treatment on one surface of the sound absorbing material.

Next, as shown in FIG. 18, the sound absorption panel of Experimental Example 12 has a normal incident sound absorption coefficient (maximum sound absorption coefficient) of about 0.93, which indicates that the sound absorption characteristics are good. Moreover, since the diameter of the through-hole of the sound absorbing material on the outdoor side is 30 μm, it is considered that intrusion of rainwater or the like can be prevented without water repellent treatment.
Next, as shown in FIG. 19, the sound absorption panel of Experimental Example 13 has a normal incident sound absorption coefficient (maximum sound absorption coefficient) of about 0.89, which indicates that the sound absorption characteristics are good. Moreover, since the diameter of the through-hole of the sound absorbing material on the outdoor side is 30 μm, it is considered that intrusion of rainwater or the like can be prevented without water repellent treatment.

“Experimental Example 14 (Water Repellency Evaluation)”
The thickness of the sound absorbing material is 0.5 to 1 mm, the diameter of the through holes is 0 to 404 μm, the through holes are arranged in a staggered pattern with a relative angle of 60 °, and the pitch of the through holes is 20 to 100 μm. Various sound-absorbing materials were produced in the same manner as in Experimental Example 1 except that the aperture ratio was 10 to 45%. Some of the sound absorbing materials were subjected to water repellent treatment. As a procedure for the water repellent treatment, first, a plating base solution having a liquid temperature of 45 ° C. was prepared by dissolving 350 g of nickel sulfamate, 45 g of nickel chloride, and 40 g of boric acid with 1 L of water. Next, 55 g of fine powder made of polytetrafluoroethylene having an average particle diameter of about 4 μm was added to 25 ml of water to which a surfactant was added at a concentration of 1 g / 100 ml, and dispersed. An electric field bath was prepared by mixing the plating base solution prepared previously with this dispersion. The temperature of the electric field bath was about 45 ° C. Next, using this electric field bath, electric field plating was performed on the sound-absorbing material under conditions of a current density of about 3 to 5 A / cm ² . In this way, the water repellent treatment was performed. The contact angle of water on one surface of the sound absorbing material treated by the water repellent treatment was about 150 °. Note that the contact angle of water means an angle formed by a tangent line in the vicinity of one surface of the water drop and the one surface when the water droplet is attached to the one surface as shown in the schematic diagram of FIG.

  Next, as shown in FIG. 21, the various sound absorbing materials obtained were installed horizontally, a hollow cylindrical body having an inner diameter of 80 mm was placed on one surface of each sound absorbing material, and water was poured into the hollow portion of the hollow cylindrical body. I put it in. Water was added to such an extent that water did not leak from the other side opposite to one side of each sound absorbing material. The height of the water column at this time was measured. The results are shown in Table 7 and FIG.

  As shown in Table 7 and FIG. 22, the sound absorbing material that was not subjected to the water repellent treatment had a water column height of about 40 mm when the diameter of the through hole was 30 μm. Even if it is installed facing it, it is expected that rainwater will be fully resistant to rainwater. On the other hand, regarding the sound absorbing material that is not subjected to water repellent treatment and the diameter of the through hole is 43 to 630 μm, the height of the water column is about 0 to 20 mm, and it is considered that the water resistance to rainwater is insufficient. It is done.

  In addition, as shown in Table 7 and FIG. 22, the sound absorbing material subjected to the water repellent treatment has a through hole diameter of 9 to 404 μm and a water column height of about 60 to 2000 mm. It is predicted that the water resistance will be sufficiently exerted.

FIG. 1 is a perspective view showing a first example of a sound absorbing material according to an embodiment of the present invention. FIG. 2 is a partial cross-sectional schematic view of the sound absorbing material of FIG. FIG. 3 is a schematic cross-sectional view showing a first example of a sound absorbing panel according to an embodiment of the present invention. FIG. 4 is a schematic cross-sectional view showing a second example of the sound absorbing panel according to the embodiment of the present invention. FIG. 5 is a schematic cross-sectional view showing a third example of the sound absorbing panel according to the embodiment of the present invention. FIG. 6 is a schematic cross-sectional view showing a fourth example of the sound absorbing panel according to the embodiment of the present invention. FIG. 7 is a graph showing the relationship between the maximum sound absorption coefficient and the aperture ratio of the sound absorbing material in Experimental Example 1. FIG. 8 is a graph showing the relationship between the maximum sound absorption coefficient and the aperture ratio of the sound absorbing material in Experimental Example 2. FIG. 9 is a graph showing the relationship between the maximum sound absorption coefficient and the aperture ratio of the sound absorbing material in Experimental Example 3. FIG. 10 is a graph showing the relationship between the maximum sound absorption coefficient and the aperture ratio of the sound absorbing material in Experimental Example 4. FIG. 11 is a graph showing the relationship between the maximum sound absorption coefficient and the aperture ratio of the sound absorbing material in Experimental Example 5. FIG. 12 is a graph showing the relationship between the maximum sound absorption coefficient and the aperture ratio of the sound absorbing material in Experimental Example 6. FIG. 13 is a graph showing the relationship between the normal incident sound absorption coefficient of the sound absorbing material and the sound frequency in Experimental Example 7. FIG. 14 is a graph showing the relationship between the normal incident sound absorption coefficient of the sound absorbing material and the sound frequency in Experimental Example 8. FIG. 15 is a graph showing the relationship between the normal incident sound absorption coefficient of the sound absorbing material and the sound frequency in Experimental Example 9. FIG. 16 is a graph showing the relationship between the normal incident sound absorption coefficient of the sound absorbing panel and the sound frequency in Experimental Example 10. FIG. 17 is a graph showing the relationship between the normal incident sound absorption coefficient of the sound absorbing panel and the sound frequency in Experimental Example 11. FIG. 18 is a graph showing the relationship between the normal incident sound absorption coefficient of the sound absorbing panel and the sound frequency in Experimental Example 12. FIG. 19 is a graph showing the relationship between the normal incident sound absorption coefficient of the sound absorbing panel and the sound frequency in Experimental Example 13. FIG. 20 is a schematic diagram for explaining a contact angle of water on one surface of the sound absorbing material. FIG. 21 is a schematic cross-sectional view for explaining a method for measuring the height of a water column in Experimental Example 10. FIG. 22 is a graph showing the relationship between the diameter of the through hole of the sound absorbing material and the height of the water column.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1, 11, 21 ... Sound-absorbing material, 2a, 21a ... One side, 2 ... Plate-shaped member, 3 ... Through-hole 10, 20, 30, 40 ... Sound-absorbing panel, 31 ... Non-hole board, 12, 22, 32, 41 ... Air layer

Claims (9)

  A sound-absorbing material comprising a plate-like member provided with a plurality of through-holes having a diameter of 30 μm or less along the thickness direction.   A sound absorbing material comprising a plate-like member provided with a plurality of through-holes having a diameter of 30 μm or more and 400 μm or less along a plate thickness direction, wherein one surface side of the plate-like member is subjected to water repellent treatment.   The sound absorbing material according to claim 1, wherein the plate-like member is made of a translucent material.   One sound-absorbing material composed of a plate-like member provided with a plurality of through-holes along the plate thickness direction and the other composed of a plate-like member provided with a plurality of through-holes having a diameter of 30 μm or less along the plate thickness direction A sound-absorbing panel, wherein the sound-absorbing material is disposed relative to each other at a predetermined interval, and the other sound-absorbing material is installed facing the outside with respect to the one sound-absorbing material.   One sound-absorbing material composed of a plate-like member provided with a plurality of through holes along the plate thickness direction, and a plurality of through holes having a diameter of 30 μm or more and 400 μm or less along the plate thickness direction and water repellent on one side Another sound-absorbing material made of a plate-like member that has been processed is disposed relative to each other at a predetermined interval, and the other sound-absorbing material is installed facing the outside with respect to the one sound-absorbing material. The sound absorbing panel is characterized in that the one surface subjected to the water repellent treatment is directed to the outdoor side.   A non-porous plate made of a translucent material and a sound absorbing material made of a plate-like member provided with a plurality of through-holes having a diameter of 30 μm or less along the thickness direction are relatively arranged at a predetermined interval. The sound absorbing panel is characterized in that the non-porous plate is installed facing the outdoors with respect to the sound absorbing material.   A non-porous plate made of a translucent material, and a sound absorbing material made of a plate-like member provided with a plurality of through holes having a diameter of 30 μm or more and 400 μm or less along the plate thickness direction and subjected to water repellent treatment on one surface side The non-perforated plate is installed facing the outside with respect to the sound absorbing material, and the one surface subjected to the water-repellent treatment of the sound absorbing material is on the outdoor side. A sound-absorbing panel characterized by being directed.   The sound absorbing panel according to any one of claims 4 to 7, wherein each of the plate-like members is made of a translucent material. The sound absorbing panel according to claim 6 or 7, wherein the non-perforated plate is provided with an opening / closing mechanism.

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