JP2001114552A - Ceramic acoustic material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a ceramic acoustic material capable of providing excellent sound absorption performances in a wide frequency range even without arranging an air layer at the other side, increasing the strength of the surface and being colored and to provide a method for producing the acoustic material. SOLUTION: In this lamination type ceramic acoustic material comprising a surface layer and an inner part layer laminated to the back of the surface layer, each layer is obtained by compounding ceramic particles with a binder, forming and baking the mixture. The inner part layer uses ceramic particles having 0.3-1.7 mm particle diameters as the ceramic particles and adjusted to 30-60% porosity. The surface layer uses particles having particle diameters equal to or larger than those of the inner part layer as the ceramic particles.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ceramic sound absorbing material used for soundproof walls of roads, railways, factories, etc., and more particularly, to a ceramic sound absorbing material exhibiting an excellent sound absorbing effect over a wide frequency range.

[0002]

2. Description of the Related Art Conventionally, a sound-absorbing material having excellent rigidity, weather resistance, water resistance and mechanical strength is used as a sound-absorbing material having high rigidity. Has been used (FIG. 2). This type of sound absorbing material utilizes voids between ceramic particles, and the sound absorbing coefficient is not always large. Therefore, in order to increase the sound absorption coefficient, it is necessary to take measures such as providing an air layer behind the sound absorbing material.

In addition, the sound absorption coefficient of the conventional ceramic sound absorbing material often shows a strong peak at a specific frequency, and since the frequency range in which sound can be absorbed is narrow, the required characteristics of the sound absorbing material such as sound absorption in a wide frequency range can be satisfied. It was not something. For this reason, various improvements and studies have been made to solve such problems.
Japanese Patent No. 45557 discloses a sound-absorbing material in which a large number of cavities of 0.5 to 5 mm are formed inside a sintered body having a particle size of 1 to 3 mm. It is stated that it can be obtained.

[0004]

Problems to be Solved by the Invention
Although the flatness of the sound absorbing performance can be obtained by the sound absorbing material described in JP-A-57-57, when the air layer is not provided behind the sound absorbing material, the sound absorbing coefficient is still not always sufficient.

An object of the present invention is to provide a ceramic sound-absorbing material which can obtain excellent sound-absorbing performance over a wide frequency range without providing an air layer behind the ceramic sound-absorbing material. Another object of the present invention is to provide a ceramic sound-absorbing material capable of increasing the surface strength and coloring.
Still another object of the present invention is to provide a method for manufacturing the above-mentioned ceramic sound absorbing material.

[0006]

Means for Solving the Problems As a result of intensive studies to solve the above-mentioned problems, the present inventor has found that the ceramic sound-absorbing material is of a laminated type using two types of ceramic particles having different average particle diameters, and the voids in the inner layer are formed. It has been found that setting the rate within a specific range increases the peak of the sound absorption rate and also increases the flatness of the sound absorption rate, and has completed the present invention. That is, the present invention is as described below.

<1> In a laminated ceramic sound absorbing material comprising a surface layer and an inner layer laminated on the back surface, each layer is obtained by mixing, molding and firing ceramic particles with a binder, respectively, Particles having a particle size of 0.3 to 1.7 mm are used as the ceramic particles, and the porosity is 30 to
The ceramic layer is adjusted to 60%, and the surface layer is a ceramic sound-absorbing material, wherein the ceramic particles are particles having a particle size equal to or larger than that of the inner layer.

<2> The ceramic sound absorbing material according to <1>, wherein the ceramic particle diameter of the surface layer is 1.5 to 2.5 times the ceramic particle diameter of the inner layer.

<3> The ceramic sound absorbing material according to <1> or <2>, wherein the ceramic particles of the surface layer have a Mohs hardness of 5 to 10.

<4> The ceramic sound absorbing material according to any one of <1> to <3>, wherein the surface layer is colored.

<5> The ceramic sound absorbing material according to any one of <1> to <4>, wherein the ratio of the thickness of the inner layer to the surface layer is 1:10 to 1: 1. is there.

<6> The ceramic sound absorbing material according to any one of <1> to <5>, wherein an interface between the inner layer and the surface layer forms an uneven surface.

<7> In a method for producing a laminated ceramic sound absorbing material comprising a surface layer and an inner layer laminated on the back surface, ceramic particles having a particle size equal to or larger than the inner layer are mixed with a binder, stirred, and then vibrated. It is molded by molding, and after mixing and stirring ceramic particles having a particle size of 0.3 to 1.7 mm and a binder on the surface of the obtained molded body, the mixture is molded by vibration molding. After drying the laminated molding,
A method for producing a ceramic sound-absorbing material, characterized by firing at 0 to 1000C for 0.5 to 3.0 hours to adjust the porosity of the inner layer portion to 30 to 60%.

<8> In the method for producing a ceramic sound absorbing material according to the item <7>, a method for producing a ceramic sound absorbing material in which pressure molding is performed instead of the vibration molding.

Hereinafter, the functions and effects of the inventions <1> to <8> will be described. In the invention of <1>, sound is hardly reflected by the presence of the surface layer, and is absorbed by the flow resistance of the inner layer. Exhibits sound absorption over the frequency range. Therefore, the peak of the sound absorption coefficient increases, and the flatness of the sound absorption coefficient also increases. To explain this point in more detail, it is preferable to use ceramic particles having an average particle diameter as small as possible to obtain flatness of sound absorption coefficient. On the other hand, there is an optimum value for the particle size of the ceramic particles for increasing the maximum value of the sound absorption coefficient, and the average particle size is preferably in the range of 1 to 2 mm. It is considered that the reason why the maximum value of the sound absorption coefficient is reduced when the ceramic particles having a small particle diameter are used is that the sound absorption on the surface is reduced due to the reduction in the particle diameter of the sound absorption on the surface, so that the sound absorption is impaired. . Investigations to reduce this reflection revealed that it is better to arrange particles having a large particle size on the surface. Further, detailed investigations revealed that a sound absorption coefficient was obtained by providing a structure in which an inner layer made of ceramic particles having a particle size of 0.3 to 1.7 mm and a surface layer made of ceramic particles having a particle size larger than that of the inner layer were provided. It was found that the peak of increased and the flatness of the sound absorption coefficient also increased.

According to the invention <2>, the effect of the invention <1> can be obtained more reliably.

According to the invention <3>, the adhesive strength of the surface layer is improved.

According to the invention <4>, the aesthetic appearance of the ceramic sound absorbing material is improved.

According to the invention <5>, the relationship between the inner layer and the surface layer is improved, and the effect of the invention <1> can be more reliably obtained.

In the invention of the above item <6>, also in the above item <1>
The effect according to the invention can be obtained favorably.

According to the invention <7> or <8>, the ceramic sound absorbing material of the present invention can be efficiently and reliably manufactured.

[0022]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be specifically described below. As shown in FIG. 1, a ceramic sound absorbing material according to one embodiment of the present invention is a laminated ceramic sound absorbing material 1 including a surface layer 2 and an internal layer 3 laminated on the back surface thereof. The inner layer 3 has ceramic particles (aggregate) having a small particle size for flattening the sound absorption coefficient, that is, a particle size of 0.3.
Ceramic particles 5 of .about.1.7 mm, preferably 0.6-1.2 mm, are used. Here, the ceramic particles are
Alumina, silica, cordieri (cordieri)
te) or other inorganic materials such as refractories or the like can be crushed or granulated.
The composition, coefficient of thermal expansion, and the like are not particularly limited.

If the ceramic particles 5 of the inner layer 3 are merely reduced, the porosity may be smaller than a predetermined value.
The sound absorption rate also decreases. In this case, it is necessary to increase the porosity by using a porosity adjusting agent to increase the maximum value of the sound absorption coefficient. As the porosity adjusting agent to be added to the inner layer, an average particle size of 0.3 to
3 mm, preferably an organic substance having an average particle diameter of 0.6 to 1.2 mm (for example, foamed PP, EPS, various polymer beads, carbon, sawdust, rubber powder, etc.), or glass foamed particles that can shrink during firing (such as pearlite) ) Can be exemplified. Such a porosity adjuster is used at the time of molding at 0 to 40
%, And sintering to reduce the porosity to 30 to 60%.
%, Preferably 35 to 50%. As a result, the maximum value of the sound absorption coefficient can be increased.

As for the particle size of the porosity adjusting agent, if the particle size is large, the maximum value of the sound absorption coefficient can be improved, but the flatness is inferior. Therefore, it is preferable to use one having the same particle size as the ceramic particles 5 of the inner layer 3.

Next, as the ceramic particles 4 of the surface layer 2, those having an average particle size equal to or larger than that of the inner layer 3 can be used to improve both the maximum value of the sound absorption coefficient and the flatness. it can. As long as the ceramic particles 4 have a larger particle diameter than the inner layer material, any aggregate can be used, and the same material as the inner layer material can be used for the surface layer 2. As the ceramic particles 4, it is preferable to use a granulated weighing aggregate produced by adding a small amount of a foaming agent to a porcelain raw material, granulating the mixture, and firing at a high temperature in a rotary kiln. . In addition, surface strength can be imparted by using an inorganic material such as alumina, silica, cordierite, or a lightweight high-strength aggregate obtained by pulverizing and granulating an inorganic material as the ceramic particles 4 of the surface layer 2. . in this case,
It is preferable to use one having a Mohs' hardness of 5 to 10, preferably 6 to 9, and a pulverized one is more preferable than a granulated one in terms of the adhesive strength of the surface layer 2. The porosity of the surface layer 2 is preferably 30 to 60%.

As for the particle size of the ceramic particles 4 of the surface layer 2, a particle having a larger particle size than the ceramic particles 5 of the inner layer 3, preferably 1.7 mm or more is effective for improving the sound absorption coefficient.

The ratio of the thickness of the surface layer 2 to the thickness of the inner layer 3 in the ceramic sound absorbing material 1 of the present invention is preferably 1:10 to 1:10.
1: 1, and within this range, the surface layer 2 and the inner layer 3
Function well to obtain a synergistic effect. Note that the interface between the inner layer 2 and the surface layer 3 does not need to be flat, and may be, for example, an uneven surface. In some cases, by forming an uneven surface, the sound absorbing performance can be enhanced.

The ceramic sound-absorbing material 1 of the present invention comprises a surface layer 2
If colored ceramic particles 4 are used,
The design of the surface can be easily increased. Further, an uneven pattern may be formed on the surface.

In producing the ceramic sound-absorbing material of the present invention, as a surface layer, preferably, 10 to 60 parts by weight of a binder is mixed with 100 parts by weight of ceramic particles having a particle diameter of 1.7 mm or more, and the mixture is stirred. Then, a molded body is formed by vibration molding. The inner layer has a particle size distribution of 0.3
A mixture obtained by mixing and stirring preferably 0 to 30 parts by weight of a porosity modifier and preferably 10 to 60 parts by weight of binder with respect to 100 parts by weight of ceramic particles of 1.7 mm in diameter is prepared. Here, a binder obtained by adding a metal oxide, a hydroxide, or the like to water glass can be suitably used as the binder.

Next, the preparation for the inner layer is placed on the molded product for the surface layer, and then molded by vibration molding. The obtained laminated molded product is dried and then dried at 800 to 1000 ° C. By firing for 0.5 to 3.0 hours, the ceramic sound absorbing material of the present invention can be obtained. Here, even if pressure molding is performed instead of the vibration molding, a sound absorbing material having equivalent performance such as sound absorbing performance can be obtained.

[0031]

Next, the present invention will be described based on embodiments. Example 1 As the ceramic particles (aggregate) of the inner layer portion, the particle diameter is 0.6 to
N-lite (manufactured by Naigai Ceramics Co., Ltd.) particles classified into 1.2 mm were used, and 100 parts by weight of this aggregate were used as a porosity regulator, 5 parts by weight of sawdust having an average particle size of 0.5 to 1 mm, and water glass-based. 25 parts by weight of a binder were mixed and stirred together. Further, as the ceramic particles (aggregate) of the surface layer, a load serum (manufactured by Inner and External Ceramics Co., Ltd.) classified into an average particle size of 1.7 to 2.5 mm was used. 25 parts by weight of a binder were mixed and stirred.

Next, the inner layer material and the surface layer material obtained as described above are arranged in order from the surface layer material to a predetermined thickness by vibration molding, and then the inner layer material is measured in a predetermined amount. It was placed on the surface layer material and molded by vibration molding. After drying the laminated molded body thus obtained, 8
By baking at 50 ° C. for 0.5 hour, a sound absorbing material having a porosity of the inner layer of 45% was obtained. With respect to the obtained ceramic sound absorbing material having a thickness of 50 mm (surface layer: 5 mm, inner layer: 45 mm), the normal incidence sound absorption coefficient was measured. The results obtained are shown in Table 2 below and FIG.

Examples 2 to 5 and Comparative Examples 1 to 3 A ceramic sound absorbing material was manufactured in the same manner as in Example 1 except that the manufacturing conditions were changed so as to have the parameters shown in Table 1 below. In addition, Example 1 was used for the obtained sound absorbing material.
The same measurement test was performed. The results obtained are shown in Table 2 below.
3 and FIG.

[0034]

[Table 1]

[0035]

[Table 2]

As is clear from Table 2 and FIG. 3, the sound absorbing materials of the examples all have a higher sound absorption peak than the comparative example, and can reduce the drop of the sound absorption coefficient near 1600 Hz. Also, the sound absorption coefficient is sufficiently high without providing an air layer behind.

[0037]

As described above, according to the ceramic sound-absorbing material of the present invention, even if no air layer is provided behind the ceramic sound-absorbing material.
Excellent sound absorption performance over a wide frequency range. In addition, the surface can be made high-strength and strengthened, and the aesthetic appearance of the sound absorbing material can be enhanced by coloring. Furthermore, according to the production method of the present invention,
The ceramic sound absorbing material can be manufactured efficiently and reliably.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a ceramic sound absorbing material according to one embodiment of the present invention.

FIG. 2 is a sectional view of a conventional ceramic sound absorbing material.

FIG. 3 is a graph showing a measurement result of a normal incidence sound absorption coefficient of an example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Ceramic sound absorbing material 2 Surface layer 3 Inner layer 4 Ceramic particles of surface layer 5 Ceramic particles of inner layer

Claims (8)

[Claims] 1. A laminated ceramic sound absorbing material comprising a surface layer and an inner layer laminated on the back surface thereof, wherein each layer is formed by mixing, molding and firing ceramic particles with a binder, respectively. Particle size 0.3 ~ as ceramic particles
1.7 mm particles are used, the porosity is adjusted to 30 to 60%, and the surface layer is a ceramic sound absorbing material, wherein the ceramic particles are particles having a particle size equal to or larger than that of an inner layer. . 2. The ceramic sound absorbing material according to claim 1, wherein the ceramic particle diameter of the surface layer is 1.5 to 2.5 times the ceramic particle diameter of the inner layer. 3. The ceramic sound absorbing material according to claim 1, wherein the ceramic particles of the surface layer have a Mohs hardness of 5 to 10. 4. The ceramic sound absorbing material according to claim 1, wherein the surface layer is colored. 5. The ceramic sound absorbing material according to claim 1, wherein the ratio of the thickness of the inner layer to the thickness of the surface layer is 1:10 to 1: 1. 6. The ceramic sound-absorbing material according to claim 1, wherein an interface between the inner layer and the surface layer forms an uneven surface. 7. A method for producing a laminated ceramic sound absorbing material comprising a front surface layer and an inner layer laminated on the back surface thereof, wherein ceramic particles having a particle size equal to or larger than the inner layer are mixed with a binder, stirred, and then subjected to vibration molding. The mixture obtained by mixing and stirring ceramic particles having a particle size of 0.3 to 1.7 mm and a binder was placed on the surface of the obtained molded body, and then molded by vibration molding. After drying the laminated molded body, it is fired at 800 to 1000 ° C. for 0.5 to 3.0 hours, and the porosity of the inner layer is 30
A method for producing a ceramic sound-absorbing material, wherein the method is adjusted to 60%. 8. The method according to claim 7, wherein pressure molding is performed instead of said vibration molding.