JPH09228506A - Sound absorbing material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sound absorber which can be constructed lighter in the weight and whose surface has the requisite functions such as fire retardancy, heat resistance, etc. SOLUTION: A porous material 4 and a sound shutoff material 6 are provided on the front and rear surfaces of a resonance structure 3 configured with a plurality of sound absorbing spaces in communication to the front surface side 1, wherein the porous material 4 has a communication hole to receive sonic waves toward the resonance structure 3 while the sound shutoff material 6 hinders the sound having passed the porous material 4 and resonance structure 3 from dispersing to the rear surface side 5. The porous material 4 is made of paper and impregnated with a liquid agent to give the requisite functions.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sound absorbing body for enhancing noise prevention performance of buildings and other structures.

[0002]

2. Description of the Related Art Conventionally, in order to improve noise prevention performance of buildings and other structures and to improve acoustic effects in rooms such as halls, for example, a sound absorber having a Helmholtz resonator structure in which a honeycomb structure and a perforated plate are combined. There is.

In this case, when a sound with a frequency close to the resonance frequency hits the entrance of the container, the air inside resonates and vibrates violently, and the frictional resistance of the neck part at that time causes a part of the sound energy to become heat energy. Since it is converted, a sound absorbing effect is generated, and it has been proposed to use a metal-based material or a resin-based material.

However, the metal-based sound absorber inevitably has a problem that its weight becomes considerably heavy, and the resin-based sound absorber has flame retardancy and flame resistance when actually used in buildings and other structures. Concerns about heat resistance remained. Usually, the surface side is usually exposed to fire and the like, so that the surface side is required to be particularly flame-retardant.

[0005]

SUMMARY OF THE INVENTION Therefore, the present invention
It is an object of the present invention to provide a sound absorbing body which can be formed with a lighter weight than that of a conventional one, and in particular, the surface side of which has a desired functionality such as flame retardancy and heat resistance.

[0006]

In order to solve the above-mentioned problems, the present invention employs the following technical means.

In the sound absorbing body of the present invention, a porous material having communication holes for receiving sound waves toward the resonance structure is formed on the front and back sides of the resonance structure forming a plurality of sound absorbing spaces which communicate with each other on the surface side, and the porous body. A sound insulating material for blocking the diffusion of the sound passing through the material and the resonance structure to the back side is arranged, and the porous material is formed of a paper material and imparts desired functionality. It is characterized by being impregnated with a liquid agent.

According to the sound absorbing body of the present invention, since the porous material is formed of paper material, the weight can be reduced, and the paper material is impregnated with a liquid agent for imparting desired functionality. You can

A plurality of sound absorbing spaces of the resonance structure, which communicate with the sound absorbing surface side, function as a cavity of the Helmholtz resonator, and a communication hole of a porous material that receives sound waves toward the resonance structure is connected to the cavity. By acting as a neck, it produces a sound absorbing effect.

Further, in this sound absorber, a porous material having a communication hole for receiving a sound wave toward the resonance structure is arranged on the front side of the resonance structure which forms a plurality of sound absorbing spaces which communicate with the surface side. The porous material is formed of a paper material and impregnated with a liquid agent for imparting desired functionality, and is installed and used so that the back surface side of the sound absorbing space of the resonance structure is closed. You can also do it.

Since this porous material is also made of a paper material, it can be made lighter in weight and the paper material can be impregnated with a liquid agent for imparting desired functionality.

Further, if the resonance structure and the sound insulation material are also made of paper material, the weight can be made lighter, and the paper material of the resonance structure and sound insulation material can be impregnated with a desired liquid agent to give a required functionality. it can.

Here, the resonance structure may have a honeycomb structure. With this structure, the sound absorber can be made extremely strong in strength. Further, the resonance structure, the porous material and the sound insulating material may be bonded and integrated. With this structure, the sound absorber can be made stronger in strength.

It is also possible that the resonance structure comprises a front-side resonance structure and a back-side resonance structure, and an intermediate porous material is interposed between them.

With this structure, noise that has passed through the porous material and entered the sound absorbing space of the front side resonance structure has its frequency component in the target region of the sound absorbing space absorbed by the damping effect, and is outside the target region of the sound absorbing space. The non-absorbed frequency component of (4) passes through the intermediate porous material and enters the back side resonance structure, and the frequency component of the target region of the sound absorbing space is absorbed by the damping effect. Furthermore, as a whole, the frequency component adapted to the sound absorbing space corresponding to the sum of the sound absorbing space on the front surface side and the sound absorbing space on the back surface side is also absorbed, and as a result, the sound absorbing body should have a very wide sound absorbing width. You can

If the porosity of the porous material is too small, it will be difficult to introduce noise into the sound absorbing space, and if it is too large, the noise once entered will leak out and 40-60% (45%).
% Is optimal).

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. (Embodiment 1) As shown in FIG. 1, the sound absorbing body of this embodiment has a front surface and a back surface of a resonance structure 3 forming a plurality of sound absorbing spaces 2 communicating with the sound absorbing surface side 1 toward the resonance structure 3. A porous material 4 having a number of minute communication holes between fibers for receiving sound waves, and a sound insulating material 6 for blocking diffusion of the sound passing through the porous material 4 and the resonance structure 3 to the back surface side 5. And are arranged.

The plurality of sound absorbing spaces 2 of the resonance structure 3 function as a cavity of the Helmholtz resonator,
It is intended and configured that the innumerable fine communication holes between the fibers of the porous material 4 that receives the sound wave toward the side function as a neck to the cavity.

In this embodiment, paper having a porosity (porosity) of about 45% was used as the paper material forming the porous material 4. If the porosity of the porous material 4 is too small, it will be difficult to introduce noise into the sound absorbing space, and if it is too large, the noise that has once entered will leak out, and should be 40-60% (around 45% is optimal). Is preferred. Then, a flame retardant was impregnated as a liquid agent for imparting desired functionality. In addition to the flame retardancy, desired functionality such as water resistance, water repellency, antibacterial property, and deodorizing property can be imparted by selecting a liquid agent to be impregnated.

As the resonance structure 3, a paper honeycomb material made of kraft paper was used. Then, a flame retardant was impregnated as a liquid agent for imparting desired functionality. In addition to the flame retardancy, desired functionality such as water resistance, water repellency, antibacterial property, and deodorizing property can be imparted by selecting a liquid agent to be impregnated. As the material of the resonance structure, a metal material such as a vinyl chloride material or a thin aluminum material, or another appropriate material can be used.

The cross-sectional structure of the resonance structure 3 can be implemented in various polygonal shapes such as a circle, an ellipse, a triangle, in addition to the hexagonal shape that constitutes the honeycomb structure. In this embodiment, the resonant structure 3 has a cell size of 10 to 25 mm.
Was used. The height (thickness) of the resonance structure is determined by the frequency of the sound to be absorbed, and the higher the height, the easier it is to absorb low-frequency sound.

As the sound insulating material 6, a thick paper suitable for processing is used, but any material having a high sound insulating property may be used, such as a synthetic resin plate, a rubber plate, an aluminum plate, a concrete plate, or a wooden board. Can also be used.

In this embodiment, the resonance structure 3, the porous material 4 and the sound insulating material 6 are all made of paper material so that they can be impregnated with a liquid agent (flame retardant) for imparting desired functionality. I have to. That is, together with the porous material 4, the resonance structure 3 and the sound insulating material 6 are also made of paper material to reduce the weight, and the paper material of the resonance structure 3 and the sound insulating material 6 is impregnated with a desired liquid agent. To provide the required functionality.

The porous material, the resonance structure and the sound insulating material were adhered and integrated by using an adhesive. Adhesion between the porous material and the resonant structure should be such that the porous material is not clogged as much as possible without impairing the porosity, and there is a gap between the sound insulation material and the resonant structure to prevent sound leakage. It was adhered so that it would not occur. The clogging on the porous material side is preferably 3% or less of the total surface area.

Next, the usage state of the sound absorbing body of this embodiment will be described. The sound absorbing body of this embodiment has a sound absorbing surface side 1
The sound insulation member 6 blocks sound waves from the above through the porous material 4 toward the resonance structure 3 and diffuses the sound passing through the porous material 4 and the resonance structure 3 to the back surface side 5. However, since the resonance structure 3, the porous material 4, and the sound insulating material 6 are made of paper material, the weight can be reduced and the paper material has a liquid absorbing property and has desired functionality. Can be impregnated with a liquid agent for imparting. In summary, since it is possible to form a lighter weight than before and to impregnate a liquid agent for imparting desired functionality, there is an advantage that desired functionality such as flame retardancy and water repellency can be imparted. .

A plurality of sound absorbing spaces 2 of the resonance structure 3 communicating with the sound absorbing surface side 1 of the sound absorbing body function as a cavity of the Helmholtz resonator, and the porous material 4 that receives sound waves toward the resonance structure 3 is provided. The innumerable minute communication holes between the fibers function as a neck to the cavity, and when a sound with a frequency close to the resonance frequency hits the entrance of the cavity, the air inside resonates violently and vibrates violently. Due to the frictional resistance of the neck portion, a part of sound energy is converted into heat energy, so that a sound absorbing effect occurs.

Further, in this embodiment, since the resonance structure 3 has a honeycomb structure and the resonance structure 3, the porous material 4 and the sound insulating material 6 are bonded and integrated with an adhesive, the sound absorbing body is made of a paper material. While being formed, it has a very strong strength due to the synergistic effect of the honeycomb structure and the integrated adhesive structure.

When a sound absorbing body is formed using a metal material,
Although it is necessary to fix each component by brazing, its workability is extremely poor, and it has the drawback of rusting over time, but this embodiment has the advantage of being inexpensive, lightweight, and easy to manufacture. is there.

Further, as compared with the case where the porous material is formed by using the flame-retardant fiber or the flame-retarded fiber, when the porous material is formed by the paper material as in this embodiment, the porosity is improved. It is relatively easy and cheap to control, and when exposed to a flame it will only carbonize and will not produce a flame, so it will not burn to other building materials and its shape will not change even if carbonized. It has the advantage of being retained.

This sound absorber can be suitably applied to applications such as flame-retardant and water-repellent sound-absorbing building materials by taking advantage of its light weight, and can be used safely by taking advantage of flame retardancy and water repellency. It can be used as a sound absorbing partition in a hospital by impregnating it with an antibacterial agent. Further, when water resistance is imparted by impregnation with a liquid agent, it can be used as a sound absorbing building material in a high humidity place such as a pool. That is, by impregnating a paper material with an appropriate chemical, it can be used as a sound absorbing material suitable for various purposes.

Further, by sandwiching a functional material having an electromagnetic shielding property, such as an aluminum foil or an electromagnetic shielding film, to a paper material forming the sound insulating material, the function of the electromagnetic shield is imparted, and the inside equipment surrounded by the sound absorbing body is It is also possible to prevent unwanted noise from picking up unnecessary noise on the outside of the panel of the sound absorber, or conversely, preventing noise of the device from leaking out of the panel.

The sound absorbing body of this embodiment is suitable for soundproofing by being attached to a vehicle or the like as a panel, and is suitable for a machine surrounding a noise source in a factory or the like by taking advantage of its light weight and flame retardancy. Can be used for

The sound absorbing body may be formed without the sound insulating material, and may be installed and used so that the back surface side of the sound absorbing space of the resonance structure is closed. That is, what is pre-installed at the site as a material to function as a sound insulation material, such as concrete, plaster, or a wall material such as metal, is used as it is. The sound absorber that has been formed without the sound insulation material is installed. (Embodiment 2) As shown in FIGS. 4 and 5, in the sound absorbing body of this embodiment, the resonance structure 3 is composed of a front surface side resonance structure 3A and a back surface side resonance structure 3B, and between them. It is assumed that the intermediate porous material 4B is interposed. The porous material 4A on the front surface side, the intermediate porous material 4B and the sound insulating material 6 are formed of paper materials, and the two resonance structures 3 are formed by opening the front and back sides by the paper honeycomb material described above. . The back side resonance structure 3B may have a bottomed cylindrical shape. And each component is adhere | attached and integrated by the adhesive agent.

Porous material 4A on the surface side and porous material 4 in the middle
The porosity of B is 40 to 60%, the height H of the front side resonance structure 3A and the height H of the back side resonance structure 3B are 20 to 50 mm, and the cell size is 10 to 25 mm.
Set to.

It should be noted that the porosity of the intermediate porous material 4B and the surface side of the intermediate porous material 4B are set so that the sound in the frequency band which is not significantly attenuated by the front side resonance structure 3A easily enters the back side resonance structure 3B. The porosity of the porous material 4A may be different.

The heights H of the front-side resonance structure 3A and the back-side resonance structure 3B are the same, but when it is desired to have a wide sound absorption frequency characteristic (described later), both resonances are generated as shown in FIG. The heights H of the structures 3 can be different.

Next, the usage state of the sound absorbing body of this embodiment will be described. When the panel of the sound absorbing body is erected around and surrounds the mechanical device that is the noise source, the noise generated from the mechanical device is diffused to the surroundings but is absorbed as follows.

Each sound absorbing space of the resonance structure 3 corresponds to an in-line Helmholtz container having a predetermined volume and height, and the pores of the porous material 4 correspond to the Helmholtz mouth having a diameter and a length. Also, the volume entering the mouth is a constant weight, and the container corresponds to a series spring, and can be handled as such a vibration system. Then, when noise composed of various high and low frequencies enters the inside of the sound absorbing space from the mouth portion corresponding to the pores communicating with the porous material 4, the vibration system damps the noise effectively in the container corresponding to the spring. Sound is absorbed. Here, the frequency component of the noise that is mainly absorbed is adapted to the height of the sound absorbing space, and the sound attenuation near that frequency becomes large.

Frequency components that are not compatible with the front side resonance structure 3A pass through the intermediate porous material 4B and the back side resonance structure 3 is present.
It penetrates into B and absorbs sound. On the other hand, as shown in FIG. 6, when the heights H of the front-side resonance structure 3A and the back-side resonance structure 3B are different, the frequency components not attenuated by the front-side resonance structure 3A are back-side resonance structures 3B. Is attenuated at.

Since the front side resonance structure 3A and the back side resonance structure 3B are connected in series, the front side resonance structure 3 is formed.
It also functions as a structure equal to the sum of the height H of A and the height H of the back side resonance structure 3B, and the height H of the front side resonance structure 3A is equal to the height H of the back side resonance structure 3B. in case of,
When the height H of the front-side resonance structure 3A and the height H of the back-side resonance structure 3B are different from each other, noise components in the vicinity of the frequency band matching the height H are mainly attenuated. A noise component near the frequency band conforming to the height H of the body 3A, a noise component near the frequency band conforming to the height H of the back side resonance structure 3B, and a frequency band conforming to the height H of the sum thereof. The noise component of is mainly attenuated. This allows sound absorption in a wide frequency band.

In summary, noise entering the sound absorbing space of the surface side resonance structure 3A through the porous material 4 is absorbed by the frequency component of the target region of the sound absorbing space due to the attenuation effect, and the sound absorbing space outside the target region of the sound absorbing space is absorbed. The frequency components that have not been processed pass through the intermediate porous material 4B and enter the back side resonance structure 3B, and the frequency components in the target region of the sound absorbing space are absorbed by the damping effect. Furthermore, as a whole, the frequency component adapted to the sound absorbing space corresponding to the sum of the front side sound absorbing space and the back side sound absorbing space is also absorbed, and as a result, the sound absorbing body should have a very wide sound absorbing width. You can

When the height H of the front side resonance structure 3A is equal to the height H of the back side resonance structure 3B, the height H is equal to the height H.
The noise component in the vicinity of the frequency band adapted to is double-absorbed, which is effective in absorbing the noise when the decibel value of the noise component is excessive.

As described above, the height H (thickness) of the resonance structure 3
In addition to changing the sound absorption space of the resonance structure 3, that is, by changing the cell size described above, or by changing the porosity of the porous material 4, the frequency band to be absorbed can be adjusted. You can

As described above, the sound taken into the resonance structure 3 is attenuated and absorbed. However, when the number of the resonance structures 3 having different heights H is further increased, the sound is absorbed. The sound can be widely absorbed from the high frequency band to the low frequency band.

It is also possible to construct a plurality of sound absorbers by alternately arranging the surfaces to be sound-absorbed in opposite directions (not shown). In this case, the room on one side sandwiching the sound absorbers can be installed. It is possible to simultaneously absorb sound with the room on the other side.
Further, the number of laminated resonant structures 3 of the sound absorbing body can be suitably implemented not only by two layers but also by three layers or more, and it should be designed as a sound absorbing body having an appropriate number of resonant structures 3 according to the noise situation at the site. You can

[0046]

Example The sound absorbing effect of the sound absorbing body of the first embodiment was evaluated as follows. (Example 1) The height (thickness) of the resonance structure 3 is 50 mm.
Then, the cell size was set to 12 mm to form a sound absorbing body (see FIG. 1). For comparison, a sound absorber having a structure in which an air space having a space of 50 mm was provided between the porous material and the sound insulating material was formed (not shown).

When the sound absorption efficiency of the sound having the frequency of 100 to 4,000 Hz was measured by the reverberation chamber method, the result as shown in FIG. 2 was obtained. The solid line shows the data of the sound absorber of Example 1, and the dotted line shows the data of the sound absorber formed for comparison.

The most noise is in the frequency range of 200 to 1,000 Hz. In this region, the sound absorption coefficient of Example 1 is 80% or more, which is very excellent. (Embodiment 2) In the sound absorbing body of Embodiment 1, in Embodiment 2, the height (thickness) of the resonance structure 3 is set to 20 mm.
The size was set to 12 mm to form a sound absorber. For comparison, a sound absorber having a structure in which an air space having a gap of 20 mm was provided between the porous material and the sound insulating material was formed (not shown).

When these were tested in the same manner as in Example 1, the results shown in FIG. 3 were obtained. Data of the sound absorber of Example 2 is shown by a solid line, and data of the sound absorber formed for comparison is shown by a dotted line.

Comparing the graphs of FIGS. 2 and 3, the sound absorption coefficients of both are improved at a frequency of 1,000 Hz or higher.
The example 2 can obtain a very good sound absorption efficiency in a high frequency range of 1,000 to 2,000 Hz as compared with the sound absorber formed for comparison.

Next, the sound absorbing effect of the sound absorbing body of the second embodiment was evaluated as follows. (Example 3) Surface side resonance structure 3A of the sound absorbing body shown in FIG.
Has a height H of 20 mm and a cell size of 12 m
m, the height H of the back side resonance structure 3B is 30 mm, the cell size is 25 mm, and the front side porous material 4 is
The porosity of A was set to 45%, and the porosity of the intermediate porous material 4B was set to 55%. When the sound absorption effect of the sound absorber was measured by the vertical incidence method, the results shown in the graph of FIG. 7 were obtained.

From this graph, it can be seen that this sound absorbing body exhibits excellent sound absorbing efficiency over a very wide frequency band. That is, it is extremely excellent in two sound absorbing characteristics, that is, good sound absorbing efficiency and wide sound absorbing frequency band.

[0053]

The present invention is configured as described above and has the following effects.

The weight can be formed lighter than before, and
Since a liquid agent for imparting desired functionality can be impregnated, it is possible to provide a sound absorber having desired functionality such as flame retardancy and heat resistance.

[Brief description of drawings]

FIG. 1 is an exploded perspective view illustrating a first embodiment of a sound absorbing body of the present invention.

2 is a graph showing the evaluation results of the sound absorbing effect of the sound absorbing body of FIG. 1 in Example 1. FIG.

3 is a graph showing the evaluation results of the sound absorbing effect of Example 2 of the sound absorbing body of FIG.

FIG. 4 is a perspective view illustrating Embodiment 2 of the sound absorbing body of the present invention.

5 is an exploded perspective view of the sound absorber of FIG.

FIG. 6 is a side view illustrating another embodiment of the sound absorbing body of the present invention.

7 is a graph showing the evaluation results of the sound absorbing effect of Example 3 of the sound absorbing body of FIG.

[Explanation of symbols]

 1 Front Side 2 Sound Absorption Space 3 Resonance Structure 3A Front Side Resonance Structure 3B Back Side Resonance Structure 4 Porous Material 4A Front Side Porous Material 4B Intermediate Porous Material 5 Back Side 6 Sound Insulation Material

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI technical display location G10K 11/162 G10K 11/16 A

Claims (7)

[Claims] 1. A porous material having communication holes for receiving sound waves toward the resonance structure, on the front and back sides of the resonance structure forming a plurality of sound absorbing spaces which communicate with the surface side, and the porous material and the resonance structure. A sound insulation material is arranged to prevent the sound passing through the body from diffusing to the back side, and the porous material is formed of paper material and impregnated with a liquid agent for imparting desired functionality. A sound absorber that is characterized by 2. A porous material having a communication hole for receiving a sound wave toward the resonance structure is arranged on the front side of the resonance structure forming a plurality of sound absorbing spaces which are communicated with the surface side, and the porous material is provided. The material is formed of a paper material and is impregnated with a liquid agent for imparting desired functionality, and the material is installed and used so that the back surface side of the sound absorbing space of the resonance structure is closed. And sound absorber. 3. The sound absorbing body according to claim 1, wherein the resonance structure is formed of a paper material and impregnated with a liquid agent for imparting desired functionality. 4. The sound absorbing body according to claim 1, wherein the sound insulating material is formed of a paper material and impregnated with a liquid agent for imparting desired functionality. 5. The sound absorbing body according to claim 1, wherein the resonance structure has a honeycomb structure. 6. The sound absorbing body according to claim 1, wherein the resonance structure, the porous material and the sound insulating material are bonded and integrated. 7. The resonance structure comprises a front-side resonance structure and a back-side resonance structure, and an intermediate porous material is interposed between the resonance structures. The sound absorber described.