JPH0891909A - Sound-absorbing material - Google Patents

Abstract

PURPOSE: To provide the sound-absorbing material enhanced in the sound- absorbing rate in the medium and low sound regions. CONSTITUTION: The sound-absorbing material is produced by allowing acicular crystals 11 comprising ettringite having a diameter of 0.1-0.4μm and a length of 1-5μm to grow on an inorganic fiber substrate 10. The sound-absorbing material is formed by subjecting the fiber substrate 10 to a prescribed hydrophilic treatment, compression-impregnating the treated substrate with a ceramic coating, and subsequently drying the impregnated substrate to allow the self-growth of the acicular crystals thereon.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sound-absorbing material, and more particularly to a sound-absorbing material for improving the sound absorption coefficient in the middle and low range by crystal-growing a needle crystal on an inorganic fiber base material.

[0002]

2. Description of the Related Art Conventionally, a sound absorbing material having a predetermined sound absorbing structure has been known as a soundproof wall panel or ceiling material. As a general structure of this sound absorbing material, there is one in which a porous inorganic fiber base material such as rock wool or glass wool is used as a sound absorbing base material, and a single plate or the like having a large number of fine pores is attached to the surface thereof. To do.

Recently, as shown in a microscopic enlarged photograph of FIG. 7, rock wool, which is a fiber base material, is caused to undergo a predetermined hydration reaction to generate a crystal, and the crystal is self-grown. It has also been proposed to produce a lumpy crystal body that is bonded to each other by the use of the lumped crystal body, thereby aiming at a certain sound absorbing effect.

[0004]

However, the conventional sound absorbing material in which a single plate or the like is attached to rock wool or the like has a property of not absorbing sound when a film having a certain thickness or more is attached, There is an inconvenience that there is not much freedom in design and it becomes difficult to secure incombustibility.

On the other hand, in the sound absorbing material using the lump crystal as shown in FIG. 7, the lump crystal increases the flow resistance in the sound absorbing body to increase the viscosity when air moves between the fiber base materials. The resistance is increased and the sound absorption performance is improved,
There are lumps of crystals so that the fibers themselves are hardly visible even in a magnified photo by a microscope.Therefore, the lumps of crystals strengthen the bonding of the fibers of the fiber base material and cause friction between the fibers and It prevents the sound absorption effect due to the vibration of the fiber itself.Furthermore, since the crystals are massive, friction between the crystals and vibration of the crystals themselves cannot be expected so much, and even the sound absorption effect by the crystals can be expected. Absent.

[0006]

SUMMARY OF THE INVENTION The present invention has been devised in order to improve the disadvantages of the prior art examples, and its object is to realize the sound absorption by the needle-shaped crystal, in addition to the sound absorption of the fiber itself. An object of the present invention is to provide a sound absorbing material which can improve the sound absorbing efficiency in the middle and low sound range and can also satisfy the nonflammability.

[0007]

In order to achieve the above object, the sound absorbing material according to the present invention comprises an inorganic fiber base material and innumerable acicular crystal bodies crystal-grown on the fiber base material. Is taking. Here, the acicular crystal has a diameter of 0.
The fiber has a length of 1 to 0.4 μm and a length of 1 to 5 μm, and is self-grown as a crystal body smaller than the fiber.

[0008]

According to the sound absorbing material of the present invention, since the crystal grown on the fibrous base material is needle-shaped, friction between needle-shaped crystal bodies and vibration of the crystal itself are possible, and at the same time, the sound absorbing material is The flow path resistance in the inside can be secured to some extent, and the sound absorbing performance can be enhanced through these actions. Also, because the crystals do not strengthen the bonding of the fibers of the fiber substrate,
The sound absorbing effect can be utilized without any inhibition of the friction between the fibers and the vibration of the fibers themselves, and the sound absorption by both the needle-shaped crystal body and the fiber base material can be excellently realized.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, an embodiment of the sound absorbing material according to the present invention will be described with reference to the drawings.

FIG. 1 shows a partially enlarged view of the sound absorbing material according to the present embodiment, and FIG. 2 shows a micrograph of an enlarged copy of the sound absorbing material. In these drawings, the sound absorbing material 10 is composed of a porous inorganic fiber base material 11 and a needle-shaped crystal body 12 crystallized in the fiber base material 11. Note that, although reference numerals are not used in FIG. 2, a thickly extending portion in FIG. 2 corresponds to the fiber base material, and a portion that appears to protrude like a needle from this corresponds to the needle crystal body 12. It is a thing.

The fiber base material 11 is made of rock wool or glass wool, while the needle-shaped crystal 12 is made of ettringite, which is made of hydrous basic calcium sulfate aluminum and has a diameter of 0. It is an extremely small number of acicular crystal bodies having a size of 1 to 0.4 μm and a length of 1 to 5 μm.

The sound absorbing material can be manufactured by hydrophilizing an inorganic fiber base material with a predetermined aqueous solution, compressing and impregnating a ceramic coating agent, and then drying for a predetermined time.

Here, the crystal growth conditions of ettringite according to this embodiment are as follows.

That is, the fiber substrate 11 is made of 2N FeSO ₄ at 3 g / l.
It is impregnated with 2 liters of an aqueous solution and dried at 100 ° C. for 18 hours to make it hydrophilic. PH1 in which 200 g of the ceramic coating agent was suspended in 2 l of pure water on the fiber base material 11
The treatment liquid of 1 is compression impregnated in a vibration tank. Immediately after the impregnation, it is wrapped in aluminum foil in a thermostat at 120 ° C. and dried for 48 hours. Then, the fiber base material immediately after being taken out from the dryer hardens and becomes a tick, but when left at room temperature for 20 hours, the powder becomes in a state of flying.

As the above-mentioned ceramic coating agent,
3N CaO, 4N SiO ₂ and 4N Al ₂ O ₃ were mixed at a molar ratio of 13: 4: 1, and sintered reaction was performed in air at 1700 ° C. for 6 hours, and then the lump was finely pulverized and sieved with a # 325 sieve. A fine powder obtained by adding 3% by weight of 2N 2 CaSO ₄ .H ₂ O powder as a reaction inhibitor is adopted.

FIG. 3 shows a test system for the sound absorbing material 10 obtained under the above-mentioned conditions. In the figure, the sound absorbing material 10 is arranged on one end side of the elongated acoustic tube 15, and the speaker 16 is arranged on the other end side of the acoustic tube 15. A probe microphone 17 is arranged in the acoustic tube 15 so as to be able to move forward and backward in the axial direction, and a fixed distance L is provided between the tip of the probe microphone 17 and the sound absorbing material 10. A Fourier transformer 18 is connected to the probe microphone 17, and a controller 19 for inputting and outputting various measurement conditions and the like is connected to the Fourier transformer 18.

A characteristic test of the sound absorbing material 10 was conducted under the following conditions using the above-mentioned test system. Specimen: Density 0.2 g / cm ³ , microphone distance L: 300, 2
70mm, temperature 14 ℃.

FIG. 4 shows the test data obtained by the above test. Here, the solid line shows the result when the back air layer is 0 mm, and the dotted line shows the normal incident sound absorption coefficient when the back air layer is 20 mm.

Comparative Example 1 Rock wool having a density of 0.104 g / cm ³ was used as a test body, which was not provided with the above-mentioned ettringite. Other conditions are the same as those described above. The test results are shown in FIG.

Comparative Example 2 As a test body, a raw rockwool fiber was hardened with a phenolic resin as a binder, and this hardened mass was added to 150
A plate was used in which the binder was hardened by hot pressing at 0 ° C for several minutes to form the fiber. Density is 0.2
It is 2 g / cm ³ . The test conditions are the same as in the above example,
The test results are shown in FIG.

As can be seen from the relative comparison of the graphs of the test results shown in FIGS. 4 to 6, 500 to 800H
It will be apparent that the sample of this example is superior to the comparative examples 1 and 2 in the normal incident sound absorption coefficient in the z region.
This is because the needle-shaped crystal body 12 obtained under the above-described conditions satisfactorily vibrates and mutually rubs, and does not extremely strengthen the bond between the fiber base materials 11, so that the fiber base material 11 itself has a constant value. This is because it vibrates to the extent that it can absorb sound.

[0022]

EFFECTS OF THE INVENTION According to the present invention, since the crystals grown on the fiber base material are needle-shaped, friction between needle-shaped crystals and vibration of the crystals themselves are possible, thereby improving sound absorbing performance. You can In addition, since the crystal does not strengthen the bonding of the fibers of the fiber base material, it is possible to take advantage of the sound absorption effect due to the friction between the fibers and the vibration of the fibers themselves. It is possible to provide a sound-absorbing material that has an unprecedented excellent effect of satisfying the property.

[Brief description of drawings]

FIG. 1 is a conceptual diagram in which a part of a sound absorbing material according to the present embodiment is enlarged.

FIG. 2 is a micrograph of a part of the sound absorbing material enlarged and photographed.

FIG. 3 is a system schematic view showing a sound absorbing material testing apparatus.

FIG. 4 is a diagram showing test results of this example.

5 is a diagram showing the test results of Comparative Example 1. FIG.

FIG. 6 is a diagram showing test results of Comparative Example 2.

FIG. 7 is a micrograph of a part of a conventional sound absorbing material taken in an enlarged manner.

[Explanation of symbols]

 11 ... Fiber base material, 12 ... Needle crystal

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display area E04B 1/82 G

Claims (1)

[Claims] 1. An inorganic fiber base material, and a diameter of 0.1 to 0.4 μm and a length of 1 to 5 μm formed by crystal growth on the fiber base material.
And a needle-shaped crystal body.