JPS62207781A - Inorganic sound absorber - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an inorganic sound-absorbing material that exhibits excellent sound-absorbing properties over a wide frequency range and is used for soundproof walls of roads, railways, factories, etc.

(Prior art) Inorganic sound absorbing materials with excellent water resistance, weather resistance, and mechanical strength have been used for outdoor soundproof walls etc. (for example, -
1 Edited by Yasumiike Uchida, “Comprehensive list of blocking materials” (1978)
．． 15), Industrial Technology Center, P, 6'53-654)
However, among the conventional inorganic sound absorbing materials of this kind, those in which inorganic particles (5) are bound together with a binder as shown in Fig. 3 have voids only between the particles, and the voids are small. As shown in Figure 2 for a conventional product, the sound absorption coefficient showed a strong peak in a specific frequency range, and its sound absorption characteristics against noise over a wide range of frequencies were not necessarily satisfactory. In order to improve the sound absorption properties of such sound absorbing materials, attempts have also been made to change the porosity and pore diameter by changing the particle size and packing density of the inorganic particles (5). However, the upper limit of the porosity of this type of sound absorbing material is about 50%, and in order to increase the porosity, it is necessary to roughly fill the particles with uniform particle size, which increases the size of the pores and reduces the complexity of the pore shape. However, if the porosity is reduced, the air flow resistance increases and the sound absorption properties are also reduced, so an effective solution could not be obtained. Furthermore, there is also an inorganic sound absorbing material with a porosity of 80 to 90%, as shown in Figure 4, which is obtained by impregnating foamed urethane with a slurry of ceramic raw materials, drying, and firing. was large, but the pore diameter was also large, and the skeleton (6) did not have communicating pores, so the pore shape was less complex and the frequency characteristics of the sound absorption coefficient showed a strong peak.

(Problems to be Solved by the Invention) The present invention has been completed with the aim of solving these conventional problems and providing an inorganic sound absorbing material having excellent sound absorbing properties over a wide frequency range.

(Means for Solving the Problems) The present invention forms a number of cavities surrounded by walls formed by the inorganic particles inside a sintered body made of inorganic particles having an average particle size of 1 to 3 fi. It is characterized by having an overall porosity of 40 to 70%.

The inorganic particles used in the present invention may be pulverized or granulated inorganic materials such as ceramics such as alumina, silica, and cordierite, and refractories, and their specific gravity, composition, coefficient of thermal expansion, etc. is not particularly limited. However, if the average particle size becomes larger than 3 mm, the pore size of the wall formed by the inorganic particles becomes too large and the sound absorption properties deteriorate, and if the average particle size becomes smaller than 1fi, the pore size becomes small. The average particle size of the inorganic particles should be 1 to 3.
Let it be mm. These inorganic particles may be mixed with a suitable binder, such as a vitreous binder, for example for 100 parts by volume.
Mixed with 40 parts by volume, itself contains 30 to 50 parts by volume.
%, and is fired so as to form interconnecting cavities with an average diameter of about 0.5 to 5 mm surrounded by walls of inorganic particles. If the porosity of the wall itself is less than 30%, it will become too dense and the overall airflow resistance will increase, resulting in a decrease in sound absorption properties, and if it exceeds 50%, the overall airflow resistance will decrease. If it is too much, the sound absorption properties will decrease, so 30 to 50%.
To form such a cavity, preferably in the range of
Organic particulates such as synthetic resins, rubber, and wood that can be burned away during firing, and inorganic particulates such as natural and human glass foam particles and lightweight aggregates that can shrink during firing, and whose particle size is 0. A method can be adopted in which 10 to 300 parts by volume of 5 to 5 parts by volume are mixed with 100 parts by volume of inorganic particles and the mixture is fired. Even if the diameter of the cavity is less than 0.5 mm, the sound absorption coefficient will decrease even if it exceeds 5 fl.In addition, when mixing raw materials, it is easier to bond inorganic particles to the surface of the granular material for forming the cavity. In addition, in order to increase the green strength of the mixture, it is preferable to add 3 to 12 parts by volume of a water-soluble organic sizing agent. By using such granules, the inorganic sound absorbing material of the present invention has a porosity of 40 to 70%. If the porosity is less than 40%, the entire structure becomes too dense and the sound absorption coefficient decreases.On the other hand, if it exceeds 70%, the air flow resistance becomes too small, resulting in a decrease in the sound absorption coefficient and the mechanical strength. will decrease. In addition,
The inorganic sound absorbing material of the present invention can be colored by adding a pigment to the binder, applying a colored glaze to the surface, etc., as necessary, and it is also possible to form an uneven pattern on the surface. Furthermore, by selecting a material with a low coefficient of expansion, it is also possible to manufacture materials with good thermal shock resistance, cylindrical shapes, and honeycomb shapes.

(Function) As shown in Fig. 1, this structure is a sintered body of inorganic particles 1) with an average particle size of 1 to 3 fi or less, and a large number of fine voids (2). In addition to being equipped with
The interior thereof has a cavity (4) larger than the cavity (2) surrounded by a porous wall (3) formed by inorganic particles (1), and the size and shape of the interior cavity. Because of its large porosity, it has a large porosity and has an appropriate flow resistance, and as is clear from the data in the examples described later, it exhibits excellent sound absorption characteristics over a wide frequency range. . Also, the whole is inorganic particles (1)
Since it is made of a sintered body, it has excellent water resistance, weather resistance, and strength, similar to conventional products.

(Example) 100 inorganic particles obtained by crushing porcelain and classifying it into various particle sizes
To the volume part, add 3 to 40 parts by volume of dry glaze powder crushed to 1 crane or less as a binder, add 3 to 12 parts by volume of an aqueous solution of starch as a sizing agent, mix for 3 to 5 minutes, and then mold into a hollow glass. Particulate matter such as particles or plastic particles from 10 to
Added 300 parts by volume. The resulting mixture is 500x500
The mixture was filled into a 50×50 mold, leveled uniformly, placed on an upper mold, and molded using a vibration pressure molding machine. The molded product was dried in a drying room at 50°C for 24 hours and then fired at 1300°C to obtain the inorganic sound absorbing materials listed in Table 1, columns 11 to 14, and columns 15 to 1.
7 is outside the range of numerical limitations, 18 to 1lh19
is a conventional product as shown in Fig. 3, which does not have a cavity inside.

In this way, the inorganic sound absorbing material of the present invention conforms to JIS^1405 "
250 to 2000H, measured with the back air layer of 100N
The average sound absorption coefficient of z shows an excellent value, for example, the sound absorption coefficient of the inorganic sound absorbing material in room 5 shows a value of 85% or more over a wide range of frequencies as shown in FIG. In addition, in Figure 2, “
The "conventional product" is the measured value of the 19th sample, and the "comparative product" is the measured value of the 16th sample.

(Effects of the Invention) As is clear from the above description, the present invention is made of a sintered body of inorganic particles and has excellent strength, weather resistance, water resistance, heat resistance, etc. It has a large number of cavities surrounded by walls having minute voids formed therein, and has a complicated shape of the voids, so it has excellent sound absorption coefficient over a wide frequency range. Therefore, the present invention greatly contributes to the development of industry by solving the problems of conventional inorganic sound absorbing materials.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing an inorganic sound absorbing material of the present invention, FIG. 2 is a frequency characteristic diagram of sound absorption coefficient, and FIGS. 3 and 4 are sectional views showing conventional inorganic sound absorbing materials. (l): inorganic particles, (2): voids (3): wall surface, (
4): Cavity. Cause 1/1) Kidney y#i-te 2: Xuan Sui 3・Ji! Mengyu: 1ran #5 j82 figure

Claims (1)

[Claims] 1. Inside a sintered body made of inorganic particles (1) with an average particle size of 1 to 3 mm, there are many walls surrounded by walls (3) formed by the inorganic particles (1). An inorganic sound absorbing material characterized by forming a cavity (4) and having an overall porosity of 40 to 70%. 2. The inorganic sound absorbing material according to claim 1, wherein the wall (3) has a porosity of 30 to 50%. 3. The inorganic sound absorbing material according to claim 1 or 2, wherein the cavity (4) has a diameter of 0.5 to 5 mm.