JP2008233794A - Method for manufacturing perforated plate sound absorbing body - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing a perforated plate sound absorbing body with which fine through-holes of several hundred micrometers in diameter can be easily and rapidly formed without requiring special members and devices. <P>SOLUTION: The method for manufacturing a perforated thin sheet 1 comprises disposing a plurality of through-holes 3 of 100 to 200 μm in average pore diameter on a thin plate 2 by successively performing a dispersion attachment process A of attaching embedding particles 4 to a surface 2a of the thin plate 2 while dispersing the particles, an embedding process B of embedding the embedding particles 4 into the thin plate 2, and a dissolving process C of removing the embedding particles 4 by swelling or dissolving the particles. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a method for producing a perforated plate sound absorber, and more particularly to a method for producing a perforated plate sound absorber that does not require a complicated process such as a photolithography technique.

  Conventionally, a sound absorbing panel is known in which a through-hole is provided in a plate-shaped member made of metal, wood, plastic, or the like, and a back air layer is provided on the side opposite to the sound source of the through-hole. In particular, a sound-absorbing panel having a through hole with a diameter of several hundreds of micrometers is characterized by excellent aesthetics because the through hole cannot be visually recognized.

Examples of means for forming a through hole of several hundreds of micrometers in a plate-like member include, for example, a pressing method (Patent Document 1) in which a needle-shaped mold is pressed against a plate material to form a through-hole, or a photolithography technique. Etching method for forming through holes by combining etching techniques (Patent Document 2), drilling method for forming through holes using a drill, leather processing method for forming through holes by laser (Patent Document 3), etc. It has been known.
JP-T-2002-521722 Japanese Patent Laid-Open No. 9-209175 Japanese Patent No. 3160084

However, in order to form a through-hole with a diameter of several hundreds of micrometers by the above-mentioned press working method, it is necessary to make the needle used as a mold very fine, and there is a problem that the mold is easily broken and the mold is easily damaged. It was. Also, if you want to change the pitch and diameter of the through holes according to the sound absorption characteristics, it is necessary to prepare a separate mold, and it may be difficult to change the specifications of the sound absorption panel according to the sound absorption characteristics . Further, there is a problem that the mold and the press are expensive.
In the etching method described above, the mask, resist, developer, stripper, etc. used for the photolithography technique are all expensive, and the exposure apparatus is also expensive, which may increase the cost. .
Furthermore, in the drilling method, although it depends on the pitch of the through holes, it is necessary to form hundreds of thousands of through holes per square meter of the sound absorbing panel one by one, and the time required for forming the through holes is enormous. There was a problem.
Furthermore, in the laser processing method, as in the drill processing method, it is necessary to form several hundreds of thousands of through holes per square meter of the sound absorbing panel, and the time required for forming the through holes becomes enormous. there were. In addition, the laser processing apparatus is expensive and may increase costs.

  The present invention has been made in view of the above circumstances, and does not require a special member or device, and can easily form a fine through hole having a diameter of several hundreds of micrometers in a short time. It aims at providing the manufacturing method of a board sound-absorbing body.

  As a result of intensive studies conducted by the present inventors to solve the above-mentioned problems, the average hole diameter and the opening ratio of the through holes are predetermined in a perforated plate sound absorber having fine through holes with an average hole diameter of about several hundreds of micrometers. To find that the desired sound-absorbing characteristics can be obtained even if the distribution of the through-holes, the hole diameter, or the pitch between the through-holes varies somewhat and the distribution thereof is relatively wide. Finally, the present invention has been completed. That is, in order to achieve the above object, the present invention employs the following configuration.

The method for producing a perforated plate sound absorber according to the present invention includes a dispersion adhesion step in which embedded particles for forming through holes are dispersed and adhered to the surface of a thin plate, an embedding step of embedding the embedded particles in the thin plate, and the embedded particles And a dissolving step of removing the particles by swelling or dissolving them, and sequentially providing a plurality of through holes having an average pore diameter of 100 μm or more and 200 μm or less on the thin plate.
Further, in the method for producing a perforated plate sound absorber according to the present invention, in the dispersion adhesion step, the embedded particles are dispersed in a dispersion to form a slurry, and the slurry is sprayed on the surface of the thin plate, thereby the embedded particles. Is preferably dispersed on the surface of the thin plate.
Moreover, in the manufacturing method of the perforated plate sound absorber of this invention, it is preferable that the thickness of the said thin plate is the range of 50-200 micrometers.
Further, in the method for producing a perforated plate sound absorber according to the present invention, the thin plate is a metal thin plate, the embedded particles are particles made of a resin, and a solution for dissolving the embedded particles can swell or dissolve the resin. It is preferable that it is a solution containing an organic solvent.
Furthermore, in the method for producing a perforated plate sound absorber according to the present invention, the thin plate is a resin thin plate, the embedded particles are particles made of metal, and a solution for dissolving the embedded particles can dissolve the metal. A solution containing an acid or a metal salt is preferable.

According to the method for producing a perforated plate sound absorber of the present invention, a perforated plate sound absorber is produced by sequentially performing a dispersion attaching step, an embedding step, and a dissolving step, so that it is easy to form fine through holes with an average pore diameter of 100 to 200 μm. Moreover, it can be formed in a short time.
Further, according to the method for producing a perforated plate sound absorber of the present invention, in the dispersion adhesion step, the embedded particles are dispersed on the surface of the thin plate by spraying the slurry containing the embedded particles, so that the pitch between the through holes is relatively uniform. A perforated plate sound absorber can be manufactured.
Furthermore, according to the method for producing a perforated plate sound absorber of the present invention, when using a metal thin plate, the resin particle is swelled or dissolved and then removed by embedding the resin particles in the metal thin plate, thereby removing the perforated plate sound absorber. Can be easily manufactured.
Furthermore, according to the method for producing a perforated plate sound absorber of the present invention, when using a resin thin plate, the perforated plate sound absorber is obtained by embedding the metal particles in the resin thin plate and then removing the metal particles by dissolving them. Easy to manufacture.

Hereinafter, a perforated plate sound absorber which is an embodiment of the present invention and a manufacturing method thereof will be described with reference to the drawings. The drawings referred to in the following description are for explaining the configuration of the sound absorbing panel and the like, and the size, thickness, dimensions, and the like of each part illustrated may differ from the dimensional relationship of the actual sound absorbing panel or the like.

FIG. 1 is a perspective view illustrating an example of a perforated plate sound absorber manufactured by the method for manufacturing a perforated plate sound absorber according to the present embodiment, and FIG. 2 is a schematic cross-sectional view of the perforated plate sound absorber shown in FIG. .
As shown in FIGS. 1 and 2, the perforated plate sound absorber 1 of the present embodiment is mainly composed of a thin plate 2 having a thickness of 50 μm to 200 μm, and this thin plate 2 has a space between one surface 2a and the other surface 2b. A plurality of through holes 3 penetrating in the thickness direction are provided. By providing a plurality of through holes 3 in the thin plate 2, sound and air can pass through the perforated plate sound absorber 1. The through-hole 3 has a function of absorbing sound as well as passing sound and air.

  If the thickness of the thin plate 2 is 50 μm or more, it is preferable that the strength of the thin plate 2 itself is not lowered and the handling becomes easy and the sound absorption characteristics are not lowered. Moreover, if the thickness of the thin plate 2 is 200 μm or less, the through-hole 3 can be satisfactorily formed as will be described later.

  In addition, the material when the thin plate 2 is formed of a metal thin plate is preferably relatively soft, and for example, aluminum, aluminum alloy, copper, or copper alloy is preferably used. When the thin plate 2 is formed of a resin thin plate, it is preferably relatively soft as in the case of metal. For example, a polyester resin such as polyethylene terephthalate, a polyolefin resin such as polyethylene or polypropylene, a synthetic rubber, a silicone rubber, or the like is used. It is preferable.

  In addition, the one surface 2a or the other surface 2b of the thin plate 2 may be provided with a design such as a picture or a pattern in order to improve the appearance of the perforated plate sound absorber 1, and each surface 2a, 2b A mirror finish may be used.

As will be described later, the through hole 3 is formed by embedding embedded particles for forming a through hole in a thin plate and then removing the embedded particles. Accordingly, the through hole 3 has various shapes such as a perfect circle shape, an elliptical shape, a rectangular shape, and an indefinite shape in plan view. Moreover, the adjacent through-holes 3 may be connected to each other so that a part of the through-holes having an indefinite shape in plan view may exist.
The average hole diameter of these through holes 3 is preferably in the range of 100 to 200 μm. If the average pore diameter is 100 μm or more, sufficient sound absorption characteristics can be secured. If the average pore diameter is 200 μm or less, it is difficult to visually recognize the through holes 3 with the naked eye, and the aesthetic appearance of the perforated plate sound absorber is improved and can be used as a decorative board. The average hole diameter is an average of the hole diameters of the plurality of through holes 3. Further, the diameter of the through hole 3 is, for example, when the shape of the through hole 3 in plan view is a perfect circle, the diameter is the hole diameter. When the shape is elliptical, the major diameter is the hole diameter. The side length becomes the hole diameter. Moreover, when the through-hole 3 is indefinite shape, the longest length becomes a hole diameter.

  Moreover, although the planar view shape of the through-hole 3 may be constant along the thickness direction of the thin plate 3 as shown in FIG. 2, a magnitude | size may change gradually along the thickness direction. That is, since all of the through holes 3 shown in FIG. 2 are schematically shown, the shape in plan view is constant along the thickness direction of the thin plate 2, and the inner wall surface 3a of the through hole 3 is a thin plate. Although formed so as to be along the thickness direction, the present invention is not limited to this, and the inner wall surface 3a of the through hole 3 may be a tapered surface or a spherical surface. The inner wall surface 3a may be a smooth surface or a rough surface. Since the through hole 3 is formed by removing the embedded particles embedded in the thin plate, the inner wall surface 3a of the through hole 3 has a shape that reflects the surface shape of the embedded particles to some extent. Formed on the surface.

  Further, the opening ratio of the through holes 3 is preferably in the range of 0.2% to 15%, and more preferably in the range of 0.5% to 10%. Here, the opening ratio of the through hole 3 is a ratio of the opening area of the through hole 3 to the area of the one surface 2a or the other surface 2b of the thin plate 2. If the aperture ratio is 0.2% or more, good sound absorption characteristics can be obtained. If the aperture ratio is 15% or less, the through holes 3 are not noticeable, and the appearance of the perforated plate sound absorber 1 is aesthetic. There is no risk of damage.

  Furthermore, since the pitch between the through holes 3 is determined by the distribution of particles when the embedded particles are dispersed in the thin plate, the pitch between the through holes 3 does not have to be completely uniform and may be uniform to some extent.

  As shown in FIG. 3, the perforated plate sound absorber 1 is combined with a back plate 11 (rigid body) that is disposed apart from the sound source side surface of the perforated plate sound absorber 1. The sound absorbing panel 12 is configured. Between the perforated plate sound absorber 1 and the back plate 11, a back air layer 13 communicating with each through hole 3 of the perforated plate sound absorber 1 is provided. In addition, a porous sound-absorbing base material represented by glass wool may be disposed in the back air layer 13. The porous sound-absorbing substrate may be, for example, a granular porous material formed by sintering or binding glass particles, mineral particles, ceramic particles, resin particles, etc., and glass fibers, mineral fibers, resin fibers, metal fibers Alternatively, a fibrous porous material in which natural fibers such as cotton are entangled may be used. In the case of a fibrous porous material, glass particles, mineral particles, ceramic particles, resin particles, or the like may be filled between the fibers.

  Next, the manufacturing method of the perforated panel sound absorber of this embodiment is demonstrated. In this manufacturing method, as shown in FIG. 4, a dispersion attaching step A in which embedded particles 4 for forming through holes are dispersed and attached to one surface 2a (surface) of the thin plate 2, and an embedding step of embedding the embedded particles 4 in the thin plate. B and a dissolution process C in which the embedded particles 4 are dissolved and removed. Hereinafter, each step will be described with reference to FIG.

(Dispersion adhesion process A)
In the dispersion adhesion step A, as shown in FIG. 4, the embedded particles 4 for forming through holes are sequentially dispersed and adhered on one surface 2a of the thin plate 2 that moves continuously in one direction. Specifically, for example, the embedded particles 4 are dispersed in a dispersion liquid such as water or alcohol to form a slurry, and this slurry is continuously sprayed onto one surface 2a of the moving thin plate 2 to thereby make the embedded particles 4 the thin plate 2. A means for dispersing and adhering to the surface can be exemplified.

  Here, as the thin plate 2, as described above, a metal or resin thin plate 2 can be used. When a metal thin plate is used as the thin plate 2, particles made of resin can be used as the embedded particles 4. More specifically, particles made of a relatively hard resin such as an acrylic resin such as polymethyl methacrylate, a polycarbonate resin, and a polyamide resin such as nylon 6, nylon 66, and nylon 12 can be used. On the other hand, when a resin thin plate is used as the thin plate 2, particles made of metal can be used as the embedded particles 4. More specifically, particles made of Cu, Al, Fe, Ni, Cr, W, Ti, NiFe alloy or the like can be used.

  The shape of the embedded particles 4 may be any shape, for example, a spherical shape, an elliptical spherical shape, a columnar shape, a needle shape, a flat plate shape, an indefinite shape, or the like.

Although the average particle diameter of the embedded particles 4 depends on the thickness of the thin plate 2, it is preferably 500 μm or less, more preferably 300 μm or less, most preferably in the range of 50 μm or more and 200 μm or less, and larger in these ranges than the thickness of the thin plate 2. Good average particle size. When the average particle diameter of the embedded particles 4 greatly exceeds the thickness of the thin plate 2 and exceeds 500 μm, for example, the embedded particles 4 are pulverized or deformed in the subsequent embedding step, and a good through hole 3 is formed. Since it may not be performed, it is not preferable. Even if the particles are not pulverized or deformed, the use of particles larger than 500 μm is not preferable because the diameter of the through hole 3 becomes excessive and the aesthetic appearance of the porous plate sound absorber 1 may be impaired.
Further, when the average particle diameter of the embedded particles 4 is significantly smaller than the thickness of the thin plate 2, for example, less than 50 μm, the embedded particles 4 may be completely embedded in the thin plate 2 and may not contribute to the formation of the through holes 3. Therefore, it is not preferable.
Furthermore, if the average particle size of the embedded particles 4 is smaller than the thickness of the thin plate, the ratio of particles having a particle size smaller than the thickness of the thin plate 2 increases, and a good through hole 3 may not be formed.

  The particle size distribution of the embedded particles 4 preferably has a relatively narrow distribution width. When the distribution width of the particle size distribution of the embedded particles 4 is excessively widened, the ratio of particles having a particle size larger than the thickness of the thin plate 2 and particles having a particle size smaller than the thickness of the thin plate 2 increases, and a favorable through hole 3 is formed. Since it may not be performed, it is not preferable.

(Embedding process B)
Next, in the embedding step B, the embedded particles 4 dispersed and attached on the one surface 2 a are pushed into the thin plate 2 to embed the embedded particles 4 in the thin plate 2. Specifically, for example, as shown in FIG. 4, the thin plate 2 is continuously passed between the twin rolls 5 and the embedded particles 4 are sequentially embedded in the thin plate 2 by roll pressure. What is necessary is just to adjust the space | interval of the rolls 5 at this time to the dimension substantially the same as the thickness of the thin plate 2, for example. Further, the linear pressure applied to the thin plate 2 by the roll 5 varies depending on the material of the thin plate 2 and the embedded particles 4 and the particle size of the embedded particles, and may be appropriately changed. Further, the roll 5 may be a rubber-like material whose roll material can be restored so that the embedded particles 4 are not crushed and the particles are exposed, and the pressure applied by the rolls may be appropriately adjusted. In this way, the embedded particles 4 are embedded in the thin plate 2.

  In FIG. 4, an example in which the embedded particles 4 are embedded in the thin plate 2 by passing the thin plate continuously supplied between the twin rolls 5, but the embedded particles 4 are obtained by continuously pressing the thin plate to a flat plate. May be embedded in the thin plate 2.

(Dissolution process C)
Next, in the dissolving step C, the through-holes 3 are formed in the thin plate 2 by swelling or dissolving the embedded particles with the dissolving liquid and removing them from the thin plate 2. Specifically, for example, as shown in FIG. 4, a solution L that swells or dissolves the embedded particles 4 may be sprayed to the continuously moving thin plate 2 with a shower nozzle or the like. Alternatively, a dissolution tank may be prepared, and the thin plate may be continuously immersed in the dissolution tank. The embedded particles 4 that have come into contact with the solution are dissolved or swollen and removed from the thin plate 2.

  Here, the solution is preferably a solution that dissolves or swells embedded particles made of metal or resin. When the embedded particles 4 are made of metal, depending on the type of metal, for example, an aqueous hydrochloric acid solution, an aqueous sulfuric acid solution, an aqueous nitric acid solution, an aqueous ferric chloride solution, etc. may be used. Further, when the embedded particles 4 are made of a resin, for example, N-methylpyrrolidone (NMP), acetone, or the like may be used depending on the type of resin.

5 and 6 are enlarged cross-sectional views of the thin plate after the embedding process and after the melting process. 5 (a) and 6 (a) are enlarged schematic cross-sectional views of the thin plate after the embedding process, and FIGS. 5 (b) and 6 (b) are enlarged schematic cross-sectional views of the thin plate after the melting step, respectively. FIG.
Referring to FIG. 5, FIG. 5 (a) shows a state in which spherical embedded particles having various particle diameters are embedded in a thin plate. The embedded particles 4a shown in FIG. 5 (a) are slightly exposed from the one surface 2a and the other surface 2b of the thin plate 2 because the particle diameter thereof is slightly larger than the thickness of the thin plate 2. Further, since the embedded particles 4b to 4d shown in FIG. 5 (a) have a particle size slightly smaller than the thickness of the thin plate 2, they are completely embedded in the thin plate (4b), or a part of the surface 2a of the thin plate 2 is 2a. Or it is in the state exposed slightly from the other surface 2b (4c, 4d).
The thin plate shown in FIG. 5 (b) was subjected to the melting step for the thin plate in such a state. In FIG. 5 (b), the through hole 3b corresponding to the embedded particle 4a was formed. The embedded particles 4b remain in the thin plate 2 without being dissolved, and the embedded particles 4c are formed with holes 3c that open on the one surface 2a side, and the embedded particles 4d are formed with holes 3d that are opened on the other surface 2b side. To do. Among these, it is the through hole 3b that expresses the sound absorption characteristic, and the remaining embedded particles 4b and holes 3c and 3d are not involved in the sound absorption characteristic at all.
As described above, according to the porous manufacturing method of the present embodiment, holes that do not participate in the sound absorption characteristics may be formed in part or embedded particles may remain. By exposing and removing from the other surface 2b, the through holes 3 having an average hole diameter of 100 to 200 μm are generally formed so as to penetrate the thin plate 2.

Referring to FIG. 6, FIG. 6 (a) shows a state where embedded particles of various shapes are embedded in a thin plate. The spherical or oval spherical embedded particles 4e and 4f shown in FIG. 6A have a particle size slightly larger than the thickness of the thin plate 2 in the same manner as the embedded particles 4a shown in FIG. It is slightly exposed from one surface 2a and the other surface 2b. Further, since the columnar embedded particles 4g shown in FIG. 6A have an aspect ratio close to 1, they are embedded along the direction in which the longitudinal direction is perpendicular to the thin plate 2. Furthermore, since the columnar embedded particles 4h shown in FIG. 6A have an aspect ratio larger than 1, they are embedded with the longitudinal direction parallel to the thin plate 2.
The thin plate shown in FIG. 6 (b) was subjected to the melting step for the thin plate in such a state. In FIG. 6 (b), the through holes 3e to 3h corresponding to the embedded particles 4e to 4h are provided. Is formed. As shown in FIG. 6, each through-hole 3e-3h has a different hole diameter corresponding to the shape of the embedded particles 4e-4h.
Thus, according to the porous manufacturing method of the present embodiment, through holes having different pore diameters may be formed, but generally, through holes having an average pore diameter of 100 to 200 μm are formed through the thin plate 2. .

According to the manufacturing method of the perforated plate sound absorber, the perforated plate sound absorber 1 is manufactured by sequentially performing the dispersion attaching step, the embedding step, and the dissolving step. Moreover, it can be formed in a short time.
In addition, since the embedded particles 4 are dispersed on the thin plate surface 2a by spraying the slurry containing the embedded particles 4 in the dispersion adhesion step, the porous plate sound absorber 1 in which the pitch between the through holes 3 is relatively uniform can be manufactured. .

Hereinafter, the present invention will be described in more detail with reference to examples.
"Example 1"
A 0.1 mm thick resin thin plate made of polyethylene terephthalate resin (hereinafter referred to as PET) and embedded particles made of spherical Cu having an average particle size of 170 μm and a maximum particle size of 300 μm were prepared. The embedded particles were dispersed in water to form a slurry, and the slurry was sprayed on the resin thin plate to disperse the embedded particles on the resin thin plate and adhere to them.
Next, the resin thin plate with the embedded particles attached was passed between twin rolls to embed the embedded particles in the thin plate. The linear pressure applied to the thin plate by the roll was adjusted to 100 MPa.
Next, the resin thin plate in which the embedded particles are embedded is immersed in an aqueous ferric chloride solution having a concentration of 30% by weight, and the liquid temperature is adjusted to about 40 ° C. to dissolve the embedded particles made of Cu. Removed. In this way, a through hole was formed. Then, the porous board sound-absorbing body of Example 1 was manufactured by washing and drying the resin thin plate.

"Example 2"
A metal thin plate made of Cu having a thickness of 0.1 mm and embedded particles made of spherical polymethyl methacrylate resin (hereinafter referred to as PMMA) having an average particle diameter of 170 μm and a maximum particle diameter of 300 μm were prepared. The embedded particles were dispersed in water to form a slurry, and the slurry was sprayed onto a resin thin plate to disperse the embedded particles on the metal thin plate and adhere to them.
Next, the metal thin plate with the embedded particles attached was passed between twin rolls to embed the embedded particles in the thin plate. The linear pressure applied to the thin plate by the roll was adjusted to 100 MPa.
Next, the metal thin plate in which the embedded particles are embedded is immersed in N-methylpyrrolidone, and ultrasonic waves are applied while adjusting the liquid temperature to about 80 ° C., thereby dissolving the embedded particles made of PMMA. Removed. In this way, a through hole was formed. Then, the porous board sound-absorbing body of Example 2 was manufactured by washing and drying the metal thin plate.

"Comparative Example 1"
A thin metal plate having a thickness of 0.1 mm made of Cu was prepared. A photoresist layer was formed on the thin metal plate, a mask was placed on the photoresist layer, and exposure and development processes were performed to pattern the photoresist layer. Thereafter, the metal thin plate was etched by a wet etching method to form a through hole. Thereafter, the perforated plate sound absorber of Comparative Example 1 was manufactured by removing the photoresist layer.

"Comparative Example 2"
A 0.1 mm thick resin thin plate made of PET was prepared. A needle-shaped mold was placed on the resin thin plate, and the through hole was formed by pressing the mold against the resin thin plate with a press. Thereafter, the perforated plate sound absorber of Comparative Example 2 was manufactured by removing the oil adhering during pressing.

“Comparative Example 3”
A thin metal plate made of Al and having a thickness of 0.1 mm was prepared. Through holes were formed on the metal thin plate by laser processing using a laser processing machine. Thus, the perforated plate sound absorber of Comparative Example 3 was produced.

About the porous plate sound-absorbing body of Examples 1-2 and Comparative Examples 1-3, the average hole diameter of the through-hole, the maximum hole diameter, the minimum hole diameter, the average pitch, and the aperture ratio were measured. Further, with respect to the perforated plate sound absorbers of Examples 1 to 2 and Comparative Examples 1 to 3 having a diameter of 100 mm, the normal incident sound absorption characteristics when the thickness of the back air layer was 50 mm were measured.
These results are shown in Table 1 and FIGS.

  As shown in Table 1, in the porous plate sound absorbers of Examples 1 and 2, the difference between the maximum hole diameter and the minimum hole diameter of the through holes is as much as 200 μm, whereas in Comparative Examples 1 to 3, the maximum hole diameter and the minimum hole diameter The difference is about 10 to 40 μm, and it can be seen that the through holes of Examples 1 and 2 have large variations in hole diameter. Nevertheless, it can be seen that Examples 1 and 2 exhibit substantially the same sound absorption characteristics as Comparative Examples 1 to 3.

  That is, as shown in Table 1, the sound absorptivity at 1 kHz of Examples 1 and 2 and Comparative Examples 1 to 3 are all about 91 to 92%. Moreover, as shown in FIGS. 7-9, the frequency dependence of the sound absorption rate in Examples 1 and 2 and Comparative Example 2 is substantially the same. From the above, it can be seen that Examples 1 and 2 and Comparative Examples 1 to 3 have substantially the same sound absorption characteristics.

  Further, in Examples 1 and 2, except that a thin plate, embedded particles and a solution are prepared, a special material is not used, and a general equipment such as a twin roll press machine is prepared. A perforated plate sound absorber having sound absorbing characteristics equivalent to those of the perforated plate sound absorbers of Comparative Examples 1 to 3 is obtained without preparing a simple device.

On the other hand, in Comparative Example 1, expensive equipment such as an exposure apparatus and an etching apparatus is necessary, and in Comparative Example 2, an expensive mold is necessary. Moreover, in the comparative example 1, the manufacturing process was complicated.
Moreover, in Comparative Example 3, it was necessary to form through holes one by one by irradiation with laser light, and it took an enormous amount of time to manufacture the perforated plate sound absorber.
As described above, in Comparative Examples 1 to 3, compared to Examples 1 and 2, the time required for production was longer and the cost was extremely high.

FIG. 1 is a perspective view showing an example of a perforated plate sound absorber according to an embodiment of the present invention. FIG. 2 is a schematic partial sectional view of the perforated plate sound absorber of FIG. FIG. 3 is a schematic cross-sectional view showing an example of a sound absorbing panel provided with the perforated plate sound absorber of FIG. FIG. 4 is a process diagram for explaining all the steps of the method for producing a perforated plate sound absorber according to the embodiment of the present invention. FIG. 5 is a process diagram illustrating a method for producing a perforated plate sound absorber according to an embodiment of the present invention. FIG. 6 is a process diagram illustrating a method for producing a perforated plate sound absorber according to an embodiment of the present invention. FIG. 7 is a graph showing the relationship between the normal incident sound absorption coefficient of the perforated plate sound absorber of Example 1 and the frequency. FIG. 8 is a graph showing the relationship between the normal incident sound absorption coefficient of the perforated plate sound absorber of Example 2 and the frequency. FIG. 9 is a graph showing the relationship between the normal incident sound absorption coefficient of the perforated plate sound absorber of Comparative Example 2 and the frequency.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Perforated plate sound absorber, 2 ... Thin plate, 2a ... One side (surface), 3 ... Through-hole, 4 ... Embedded particle

Claims (5)

  A dispersion and adhesion step of dispersing and adhering embedded particles for forming through holes on the surface of the thin plate; an embedding step of embedding the embedded particles in the thin plate; and a dissolution step of removing the embedded particles by swelling or dissolving. A method for producing a perforated plate sound absorber, which is sequentially performed, and a plurality of through holes having an average pore diameter of 100 μm or more and 200 μm or less are provided in the thin plate.   2. The dispersion adhesion step, wherein the embedded particles are dispersed in a dispersion liquid to form a slurry, and the slurry is sprayed on the surface of the thin plate to disperse the embedded particles on the surface of the thin plate. The manufacturing method of the perforated plate sound-absorbing body described in 1.   The thickness of the said thin plate is the range of 50-200 micrometers, The manufacturing method of the perforated panel sound absorber of Claim 1 or Claim 2 characterized by the above-mentioned.   The thin plate is a metal thin plate, the embedded particles are particles made of a resin, and the solution for dissolving the embedded particles is a solution containing an organic solvent capable of swelling or dissolving the resin. The manufacturing method of the perforated panel sound absorber in any one of Claims 1 thru | or 3.   The thin plate is a resin thin plate, the embedded particles are particles made of a metal, and the solution for dissolving the embedded particles is a solution containing an acid or a metal salt capable of dissolving the metal. The manufacturing method of the perforated panel sound absorber in any one of Claims 1 thru | or 3.

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