JP3476975B2 - Sound absorbing material - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure of a calcium silicate hydrate-based sound absorbing material used as a part of a building in the field of civil engineering and construction.

[0002]

2. Description of the Related Art Conventionally, a calcium silicate hydrate-based sound absorbing material has been known (JP-A-52-37403).
According to this known technique, the sound absorbing material is obtained by stirring a foaming agent such as sodium dodecylbenzenesulfonate or nonylphenyl tetraethylene oxide ether sulfate with air and water to obtain an emulsion containing fine bubbles, and the emulsion thereof. To obtain a foam concrete slurry by mixing with a raw material for producing a sound absorbing material, a step of casting the foam concrete slurry into a mold, and molding, and an autoclave curing the concrete porous body obtained in the step. It is manufactured through the steps.

[0003]

Since the sound absorbing material obtained by the above-mentioned known technique has fine air bubbles continuously present, the sound absorbing material has excellent sound absorbing characteristics, but the sound absorbing material has a higher sound absorbing property. There is still room for improvement in applications where mechanical properties, especially compressive strength, are desired. For example,
In the case where the sound absorbing material is to be used as a wall material on the indoor side of a building that requires sound absorption by being combined with other building materials, if the sound absorbing material has a low compressive strength, the sound absorbing material may have other beats. When the rigid body collides, there is a problem that the surface of the sound absorbing material, that is, the wall material, is partially retracted, and the sound absorbing material has a problem that the sound absorbing material is easily damaged during the transportation process.

However, in this type of sound absorbing material, it is difficult to improve the compressive strength while maintaining the sound absorbing characteristics to some extent. This is because in order to improve the sound absorption characteristics, it is necessary to increase the number of pores in the sound absorbing material and to make bubbles continuous with each other. When the number of pores is increased, the solid structure (matrix) that is the constituent layer of the sound absorbing material forming the pores This is because the number of layers is reduced, and the compressive strength of the sound absorbing material is inevitably lowered.
According to the above-mentioned known technique, when the matrix layer is increased in order to increase the compressive strength, the number of pores is reduced, and as a result, the number of continuous pores is reduced and the sound absorbing property is deteriorated.

Therefore, the inventors of the present invention have conducted extensive studies to solve this problem, and as a result, produced a sound absorbing material in which many of the continuous pores face a specific direction and use the sound absorbing material. At this time, the fact that the continuous pores should be used in such a manner as to face a specific direction was found, and the present invention was completed. Therefore, an object of the present invention is to provide a calcium silicate-based sound-absorbing material capable of further improving mechanical properties without substantially reducing the sound-absorbing properties.

[0006]

SUMMARY OF THE INVENTION In order to solve the above problems, the present invention uses a siliceous raw material and a calcareous raw material as a sound absorbing material.
Water slurry, which is the main raw material for manufacturing, is used as a foaming material.
In the form in the presence of luminium, thickeners and surfactants
The process of foaming and curing with to obtain a semi-plasticized cured product
(Semi-plasticized product manufacturing process) and the cured product obtained in that process
Through the process of steam curing under high temperature and high pressure (curing process)
A sound-absorbing material to be produced , which comprises calcium silicate hydrate having a bulk specific gravity of 0.2 to 0.5 and including a large number of substantially spherical pores, wherein a plurality of pores adjacent to each other are present. , Partially connected to form continuous pores that are continuously connected through communication holes formed between them, and a large number of the continuous pores are foamed in the semi-plastic material manufacturing process.
The sound absorbing material is arranged so as to face the horizontal direction at the time .

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION Next, the manufacturing method, structure, function and effect of the sound absorbing material will be described. First, the sound absorbing material according to the present invention has a bulk specific gravity of 0. It consists of 2-0.5 calcium silicate hydrate. This sound absorbing material has two main steps, namely, a water slurry containing siliceous raw material and calcareous raw material as main raw materials for the production of a sound absorbing material in a mold in the presence of a foaming material, a thickener and a surfactant. Produced through a process of foaming and curing to obtain a semi-plasticized cured product (semi-plasticized product manufacturing process), and a process of curing the cured product obtained in that process with steam at high temperature and high pressure (curing process) To be done.

As the siliceous raw material, one or more kinds of SiO ₂ containing compounds such as quartz, cristobalite, silica sand, fly ash, slag and silica fume are used. Further, as calcareous raw materials, quick lime, slaked lime,
One kind or two or more kinds of Ca-containing compounds such as various Portland cements are used, but the stability of bubbles generated in the reaction system in the semi-plasticization manufacturing process and the water slurry until semi-plasticized and hardened Considering the shortening of the curing time, etc., Portland cement, particularly normal Portland cement, early-strength Portland cement, and moderate heat Portland cement are preferably used.

Further, in the above manufacturing method,
The crushed debris of the semi-plastic material generated in the manufacturing process of the light weight air bubble concrete (ALC) cured by steam under a high pressure atmosphere or in the manufacturing process of the sound absorbing material according to the present invention stabilizes the air bubbles, and When cement is used, it can be used as a part of the above-mentioned siliceous raw material and calcareous raw material in order to stabilize the hydration reaction of the cement.

The crushed waste is used in an amount of 30% by weight or less, preferably 5 to 20% by weight, based on the total solid content of the siliceous raw material and the calcareous raw material. When the amount of the crushed scraps used exceeds 30% by weight, the strength of the semi-plastic material is lowered under normal production conditions, and the strength required for demolding or processing cannot be achieved. When crushed waste is used in the above step, it is not necessary to use calcareous raw materials other than this raw material and cement. In this case, 1 to 5 parts by weight of gypsum based on the solid content is used together.

Further, by using aluminum metal powder as the foam material in the semi-plastic material manufacturing step, it becomes possible to form continuous pores oriented in a specific direction in the sound absorbing material according to the present invention. . The mechanism of continuous pore formation is not necessarily clarified, but it is considered as follows.

The metal powder of aluminum reacts with the alkali of the water slurry to generate hydrogen gas, and in the process (foaming process) of the raw water slurry being semi-plasticized, the hydrogen gas collects into bubbles and becomes water. Push up the slurry. On the other hand, gravity acts on the plasticizing water slurry, and the rising bubbles try to escape in the horizontal direction due to the gravity effect of the water slurry. In addition, since the viscosity of the water slurry increases as it is plasticized, the viscous energy of the water slurry becomes larger than the foaming energy of hydrogen gas, and as a result, the water slurry tends to push down the bubbles. The bubbles that have been subjected to these actions become elliptical shapes that are long in the horizontal direction and are arranged in the direction orthogonal to the rising direction, that is, in the horizontal direction.

In addition, since a large amount of aluminum metal powder is used in the above method, a large number of bubbles are generated in the reaction system, and the bubbles expand to a larger extent due to the heat of hydration reaction of the same system. The elliptical bubbles arranged close to each other in the horizontal direction easily come into contact with each other. as a result,
As shown in FIG. 1, in the reaction system R, an elliptical bubble 1 and a bubble 2 on the side adjacent to the ellipse form a beaded bubble 3 by horizontally coalescing. This beaded bubble 3 becomes an important element that becomes a continuous pore described later.

The continuity and directionality of the bubbles in the reaction system can be explained as described above. Generally, when the bubbles contact each other in the reaction system, the bubbles coalesce when the surface tension of the bubble shell is large. It's going to be one big bubble, so you need to stop it. Therefore, a surfactant is added to the water slurry in the step of manufacturing the semi-plastic material according to the present invention.

This surface-active agent is not used for mechanical action of the water slurry, for example, for foaming it by stirring, but the interface between the bubbles generated by the chemical reaction of aluminum in the reaction system and the water slurry is not used. Used for the purpose of activation. Thus, although any surfactant that is suitable for this purpose can be used, preferably sulfuric acid esters of higher alcohols are used. In this case, the surfactant is added to the reaction system when the reaction system is in the temperature range of 60 to 80 ° C. Furthermore, in order to appropriately suppress the resistance when the bubbles of the reaction system according to the present invention move so that the bubbles are continuously arranged in the horizontal direction, a thickener, preferably methylcellulose, is added to the reaction system. Is added.

After the raw materials and additives are prepared, the siliceous raw material and the calcareous raw material are mixed with water to form silica (SiO 2
₂ ) / Calcium oxide (CaO) ratio of 0.3-1
The water slurry of the raw material is prepared, and 0.1 to 2.0 parts by weight of the thickener and 1.0 to 3 parts of the surfactant are added to 100 parts by weight of the solid content of the raw material with respect to the obtained water slurry. 0.0 parts by weight and 0.05 to 0.2 parts by weight of aluminum metal powder, respectively, to obtain a viscosity of 400 to 2500 cps. It is a mixture of. Then, the mixture is cast into a mold to foam and cure.

Next, the thus obtained semi-plastic material is cut into a molded product having a predetermined size and shape, typically a panel-shaped molded product, and the molded product is put in an autoclave and heated. When cured for 2 to 8 hours in a saturated steam atmosphere at 150 to 200 ° C. and a pressure of 8 to 20 atm, preferably 9 to 12 atm, the semiplastic material turns into calcium silicate hydrate represented by tobermorite. The sound absorbing material according to the invention. When the semi-plastic material is cut into a molded product, the semi-plastic material is cut in a direction orthogonal to the arrangement direction of the beads in the semi-plastic material. By doing so, it becomes possible to obtain a molded body that is cut so as to be substantially orthogonal to the direction in which the continuous pores described below extend.

The sound-absorbing material thus obtained is cut in a direction orthogonal to the horizontal direction of the mold when a semi-plastic material as its precursor is present in the mold, and its cut surface is cut. When viewed with a scanning electron microscope, it is observed that the sound absorbing material 4 includes a large number of pores 5 having a diameter of about 0.1 to 2 mm, as schematically shown in FIG. A plurality of pores adjacent to each other among the pores 5 are partially united to each other, and the pores have a diameter of about 0.01 to less than the diameter of the pores 5.
The continuous pores 7 are formed through the communication holes 6 having a diameter of 1.5 mm.

[0019] That is, the orientation direction Y of the continuous pores 7
Cutting the sound absorbing material 4 according to the present invention along a direction orthogonal to each other,
When the cut surface is photographed with the microscope, as shown in FIG. 4, a plurality of adjacent pores are continuously connected to each other through a communication hole to form a continuous pore.

The longitudinal direction of the continuous pores corresponds to the horizontal direction in which the semi-plastic material was present in the mold in the semi-plastic material manufacturing process. This is because the film 8 formed between the adjacent bubbles 1 and 2 in the beaded bubble 3 in the reaction system R shown in FIG. 1 is destroyed in the curing step, and as shown in FIG. It is considered that the bead-shaped bubbles became continuous pores 7 because the portion where the film was present became the communication hole 6 smaller than the diameter of the bubbles 1 and 2.

The bulk specific gravity (mass per unit volume including pores) of the sound absorbing material is 0.2.
Is in the range of 0.5. Further, when the total area of the cross-sections of the pores and the total area of the cross-sections of the continuous pores in the photograph are calculated, the area (C) of the former is set to the area ratio (C / A) to the area (A) of the cut surface. The area (B) of the latter is the same as the area (A) of the cut surface (B / A) in the range of 0.4 to 0.9.
If the sound absorbing material is in the range of 7 and has the area ratio of continuous pores in this range, the above-mentioned problems can be sufficiently achieved.

Next, this sound absorbing material is used as it is, or is further cut / cut to be used as a cover or a casing of a wall surface of a building or a machine or device that generates noise. In these usage modes, the direction in which the continuous pores face is made to coincide with the propagation direction of the sound to be absorbed. If the sound absorbing material is used as a wall surface, the former direction is perpendicular to the wall surface.

Then, the sound propagated from the outside to the continuous pores of the sound absorbing material directly or through the matrix layer which is a layer other than the continuous pores is transmitted to the long air layer in the continuous pores, and thus 125 to 125 It attenuates in a wide frequency band of 2000 Hz. Furthermore, since there are communication holes in the middle of the continuous pores that are smaller than the diameter of the pores, some of the sound that has entered the pores cannot pass through the communication holes, collides with the wall surface of the pores, is reflected, and again forms the air layer. Enter and decay.

The process up to this step is the same as in the prior art,
In the sound absorbing material according to the present invention, a large number of continuous pores are almost the same.
Since it is oriented in one direction (horizontal direction) , the sound attenuation effect from the direction is larger than that of the sound absorbing material according to the prior art in which the continuous pores are randomly oriented.

Therefore, if the sound absorbing material according to the present invention has the same mechanical characteristics as those of the prior art, it is possible to use it as a sound absorbing material for absorbing sound coming from a specific direction. The sound absorbing property of the sound absorbing material according to the present invention can be made higher than that of the prior art, and conversely, if the sound absorbing properties are the same, the mechanical property can be improved.

[0026]

EXAMPLES Next, the effects of the present invention will be specifically described with reference to examples. (Semi-plastic material manufacturing process) 60 parts by weight of silica sand, 2 parts by weight of crushed semi-plastic material generated in the ALC manufacturing process, and 2 parts by weight of gypsum are mixed with 90 parts by weight of water to prepare a water slurry. did. To this water slurry, 38 parts by weight of early-strength Portland cement and 1 part by weight of methyl cellulose were added and mixed, respectively, and further, 0.2 parts by weight of metal powder of aluminum and 2 parts by weight of sulfuric acid of higher alcohol. The ester was added to prepare a raw material mixture for manufacturing the sound absorbing material.
The viscosity of this raw material mixture is 700 to 800 cps. When it became the formwork (60 cm x 2000 cm x 7
It was cast in 0 cm) and foamed and cured.

(Curing step) Next, the semi-plasticized material obtained in the above-mentioned step is taken out from the mold, and the semi-plasticized material corresponds to a direction orthogonal to the horizontal direction when it is in the mold. Cut in the direction you want to. The obtained plurality of panel-shaped molded bodies were put into an autoclave and aged for 6 hours in a steam atmosphere at a temperature of 180 ° C. and 10 atm to obtain a sound absorbing material of the present invention.
Then, when a part of the sound absorbing material was sampled and powdered and analyzed by an X-ray diffraction method, it was found to be tobermorite and quartz.

Similarly, when the bulk specific gravity of the sound absorbing material is measured,
The value was 0.39. Moreover, when the cut surface was photographed with a scanning electron microscope (JSM-T20 manufactured by JEOL Ltd.), a large number of pores were observed in it as shown in FIG. a plurality of pores that are partially coalesce, a state that is a continuous pores observed et a via a small communication hole than the diameter of their pores. And, the continuous vesicles shaped like an ant shellet, a part of beads or a skewered dumpling face almost the same direction (horizontal direction) , and the continuous stomata of the continuous stomata are judged from the cutting direction of the semi-plastic material in the curing step. It was found that the arrangement direction was orthogonal to the direction in which the hydrogen gas became bubbles and rose in the semi-plasticized material manufacturing process.

Next, two sheets of the above-mentioned photograph of FIG. 4 were non-color-copied by a dry copying machine, all the pores shown in one of them were dyed black, and the other one had only continuous pores. It was dyed black and corrected in the same manner as above. Then, these modified photographs are analyzed by an image analysis device (TVI manufactured by Nippon Avionics Co., Ltd.).
P-4100) is used to determine the area of the black surface per unit cross-sectional area (A) as the area of pores (C) and the area of continuous pores (B), the former is the area of unit cross-section (A).
The area ratio (C / A) is about 0.77, whereas the latter area (B) is the same as the unit cross-sectional area (A).
The area ratio (B / A) was about 0.45.

Further, the sound absorbing material is 10 cm × 10 cm.
A test piece was prepared by cutting out into 10 cm lumps, and a compression test was performed on the test piece (testing apparatus: compression tester manufactured by Instron Co., Ltd.). The compression strength of the test piece was 20 k.
It was gf / square cm.

Finally, the sound absorbing material has a diameter of 91.5 m.
m, and another 70 mm-thick cylindrical test body was prepared, and JI
The normal incident sound absorption coefficient of the test body was measured according to S A 1406. The results are shown in Table 1. As is clear from Table 1, the test body of this example exhibited a higher sound absorption coefficient than the test body of the comparative example described later in the frequency range of 400 to 2000 Hz.

[0032]

[Table 1]

[0033]

[Comparative Example] For comparison, a commercially available calcium silicate-based sound absorbing material according to the prior art was cut into the same shape and size as in the example to prepare a test body, and the test body was evaluated in the same manner as above. did. Further, the cut surface was photographed with a scanning electron microscope as in the example. As a result, as shown in FIG. 5, the number of pores per unit area was about 1.2 in the example.
In total, the total area of pores was about 70%. However, the area of the continuous pores was as small as about ⅕ of that in the example, and the directionality could not be found in it. The sound absorption coefficient of the test body of this comparative example is as shown in Table 1 above.
Although slightly higher than that of the test body of the above-mentioned example in the frequency range of 125 Hz or more and less than 400 Hz,
In the above range, the compressive strength was clearly lower than that of the test piece of the example, and was 49% of that of the example.

The following can be said from the above examples and comparative examples. Regarding the sound absorption characteristics, it can be said that the comparative example is superior to the examples in the frequency range of 125 to 400 Hz, but the examples are clearly superior to the comparative examples in the sound absorption characteristics and the compression strength in the frequency range of 400 Hz or more. ing. This is because the total area of the pores is smaller in the embodiment, and the portion other than the pores, that is, the matrix layer is larger in the embodiment, and as a result, the compressive strength is increased.

In addition, the sound absorbing characteristic of the embodiment is superior to that of the comparative example in a specific frequency range despite that the total area of the pores is small, because the sound absorbing material of the embodiment has many continuous pores. . This means that the sound absorption characteristics of the example can be further improved by setting the compressive strength of the example to the same level as that of the comparative example.

[0036]

As described in detail above, the present invention exhibits an excellent effect that the mechanical characteristics can be further improved without substantially lowering the sound absorbing characteristics of the calcium silicate-based sound absorbing material.

[Brief description of drawings]

FIG. 1 is a conceptual diagram illustrating a tendency of bubbles in a reaction system in a manufacturing process of a sound absorbing material according to the present invention.

FIG. 2 is a partial cross-sectional view showing a part of the sound absorbing material in a cutaway manner.

FIG. 3 is a conceptual diagram illustrating a process of generating continuous pores.

FIG. 4 is a photograph showing a cross section obtained by cutting the sound absorbing material obtained in the example along a direction orthogonal to the direction in which the continuous pores are oriented, by photographing with a scanning electron microscope.

FIG. 5 is a photograph showing a cross section obtained by cutting a conventional sound absorbing material in the same manner as in the example, by photographing with a scanning electron microscope.

[Explanation of symbols]

1 air bubble 2 bubbles 3 beads beads 4 Sound absorbing material 5 pores 6 communication holes 7 continuous pores A cross section of sound absorbing material B Cross-sectional area of continuous pores R reaction system

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kenki Matsuo 2035 Shimoi, Shimoi-cho, Owariasahi-shi, Aichi Onoda ALC Co., Ltd. Material Research Laboratory (56) Reference JP-A-3-83873 (JP, 83873) A) JP-A-52-37403 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) C04B 38/00-38/10

Claims (2)

(57) [Claims] 1. A water slurry containing a siliceous raw material and a calcareous raw material as main raw materials for producing a sound absorbing material is foamed in a mold in the presence of metallic aluminum as a foaming material, a thickener and a surfactant. It is manufactured through a process of curing to obtain a semi-plasticized cured product (semi-plasticized product manufacturing process) and a process of curing the cured product obtained in that process with steam at high temperature and high pressure (curing process). It is a sound-absorbing material and has a bulk specific gravity of 0, which includes a large number of substantially spherical pores (5).
2 to 0.5 of calcium silicate hydrate, a plurality of pores adjacent to each other among the pores are partially united, and continuous through a communication hole (6) formed between them. The sound absorbing material has continuous pores (7) that are continuously connected to each other, and a large number of the continuous pores are arranged in the horizontal direction at the time of foaming in the semi-plastic material manufacturing process. 2. A cross section (B) occupied by the continuous pores (7) in a cut surface (A) along a direction orthogonal to the horizontal direction has an area ratio (B / A) of 0.2 to 0. The sound absorbing material according to claim 1, which is in the range of 7.