JP3444589B2 - Resin composition for acoustic reflection reducing material and acoustic reflection reducing 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 resin composition and a sound wave reflection reducing material for molding a sound wave reflection reducing material to be mounted on a structure or the like, and more particularly to a low specific gravity filler and a high specific gravity filler. TECHNICAL FIELD The present invention relates to a resin composition for a sound wave reflection reducing material and a sound wave reflection reducing material, which enable uniform dispersion of and.

[0002]

2. Description of the Related Art In order to reduce acoustic reflection sound reflected by structures provided in the vicinity of audio equipment, a sound wave reflection reducing material is attached and used on the outer wall surfaces of the structures. In such a sound wave reflection reducing material, the propagation velocity c and the elastic loss coefficient η
By appropriately adjusting the propagation constant γ of the sound wave reflection reducing material and the density ρ of the sound wave reflection reducing material, the necessary reflection reducing effect can be obtained.

By the way, in the conventional thin sound wave reflection reducing material, for example, a viscoelastic material such as soft rubber is mixed with a filler such as alumina, and the bubbles adhered to the surface of the filler are used for viscoelasticity. It has a structure in which bubbles are contained in the material. In such a sound wave reflection reducing material, the acoustic propagation constant γ is changed by including bubbles in the viscoelastic material.

There is also known a sound wave reflection reducing material formed by filling a hard balloon such as a glass balloon in a viscoelastic material. In such a sound wave reflection reducing material, the acoustic propagation constant γ is changed in the same manner as above by including the bubbles in the hard balloon in the viscoelastic material.

Further, Japanese Patent Publication No. 7-94608 discloses that
A sound reflection reducing material in which microballoons having soft walls are dispersed in a soft reactive resin has been proposed. This sound wave reflection reducing material has a microballoon having a soft wall in a soft reactive resin, so that it can be deformed by sound pressure to sufficiently change the acoustic propagation constant, and the natural acoustic The impedance can be accurately adjusted to a desired value.

However, in the above-mentioned conventional sound wave reflection reducing material, a low specific gravity filler such as a microballoon is mixed with a viscoelastic material such as a resin and a high specific gravity filler for adjusting the specific acoustic impedance. In that case, there is a problem that the filler is separated in the material during the curing reaction of the resin composition, and a sound wave reflection reducing material in which these fillers are uniformly dispersed cannot be obtained. In particular, such a problem was noticeable when an attempt was made to form a thick sound wave reflection reducing material.

[0007]

DISCLOSURE OF THE INVENTION An object of the present invention is to provide a resin composition for a sound wave reflection reducing material and a sound wave reflection reducing material capable of uniformly dispersing a low specific gravity filler and a high specific gravity filler. Especially.

[0008]

[MEANS FOR SOLVING THE PROBLEMS] The resin composition for a sound wave reflection reducing material of the present invention for achieving the above object is a reaction curable resin which makes a filler in a non-fluid state within 30 seconds from the start of the reaction. Characterized by dispersing a low specific gravity filler having a specific gravity of 0.01 to 0.10 and a high specific gravity filler having a specific gravity of 2 to 10 consisting of a microballoon having a soft wall that is deformed by sound pressure. Is.

The sound wave reflection reducing material of the present invention is characterized by being obtained by curing the above resin composition.

Since the reaction curable resin has such a viscosity that the filler does not flow within 30 seconds from the start of the reaction, the low specific gravity filler and the high specific gravity filler are uniformly mixed with the reaction curable resin. By doing so, the low specific gravity filler and the high specific gravity filler can be uniformly dispersed in the sound wave reflection reducing material after the curing reaction.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION The structure of the present invention will be described in detail below with reference to the accompanying drawings.

FIG. 1 illustrates a sound wave reflection reducing material according to an embodiment of the present invention. In the figure, the sound wave reflection reducing material 1 has a specific gravity of 0.01 to 0.01 with respect to the soft reaction curable resin 2.
Micro balloon 3 as a low specific gravity filler of 0.10,
It is formed by curing a resin composition for a sound wave reflection reducing material, in which powder particles 4 are uniformly dispersed as a high specific gravity filler having a specific gravity of 2 to 10.

The resin composition for a sound wave reflection reducing material exhibits a viscosity in a fluid state immediately after the initiation of the curing reaction, and reaches a viscosity at which each filler is brought into a non-fluid state within 30 seconds after the initiation of the curing reaction. It has a thickening property. The viscosity in a fluid state is 300 to 5000 mPa · s. The viscosity that makes each filler non-fluid is 20,000 m.
Pa · s.

As the reaction curable resin 2, it is preferable to use a room temperature fast curing type polyurethane resin or the like. Room temperature quick-curing polyurethane resin is 300 to 50 before the start of the curing reaction.
It has a viscosity of 00 mPa · s and 3 from the start of curing reaction.
A viscosity of 20000 mPa · s is reached within 0 seconds.

Microballoons 3 are preferably used as the low specific gravity filler. This micro balloon 3
Has a soft wall.

As the high specific gravity filler, powdery or granular material 4 having a specific gravity of 2 to 10 can be used. The acoustic reflection reducing material 1 having a desired specific gravity can be obtained by adding a high specific gravity filler corresponding to the required specific gravity. As described above, since the specific gravity can be changed even when the propagation speed of the sound wave reflection reducing material is slower than that of the propagation medium, it is possible to adjust the specific acoustic impedance of the sound wave reflection reducing material to the same level as that of the propagation medium. Become.

The above-described sound wave reflection reducing material 1 of the present invention has a resin composition for a sound wave reflection reducing material that exhibits a viscosity in a fluid state immediately after the start of the curing reaction, and within 30 seconds from the start of the curing reaction, each filler. Reaches the viscosity that makes
After the curing reaction, it is possible to uniformly disperse the microballoons 3 as low specific gravity fillers and the powder particles 4 as high specific gravity fillers.

Since the sound wave reflection reducing material 1 has the microballoons 3 having soft walls in the soft reaction curable resin 2, the sound wave reflection reducing material 1 is deformed by the sound pressure, and the sound wave reflection reducing material 1 is deformed. The acoustic propagation constant of the reducing material 1 can be changed sufficiently.

Next, the test results of the sound wave reflection reducing material according to the present invention will be described.

In this test, a normal temperature fast-curing polyurethane was mixed with a microballoon having a soft wall and a high specific gravity filler, and the content of the microballoon was changed so that the content of the microballoon was large.
Medium and small resin composition M ₁ , M ₂ for sound wave reflection reducing material,
To prepare a M _3.

Further, a resin composition M ₄ for a sound wave reflection reducing material was prepared which contained only the same amount of microballoons as the resin composition M ₁ in normal temperature rapid curing type polyurethane and did not contain a high specific gravity filler. Measurement of Propagation Velocity Three kinds of sound wave reflection reducing materials 1 having a thickness of 25 mm and a length and width of 400 mm were manufactured from the above resin compositions M ₁ , M ₂ and M ₃ .

These three types of sound wave reflection reducing materials 1 are shown in FIG.
As shown in FIG. 4, the wave transmitter A and the wave receiver B are arranged so as to face each other on the central axis y-y of the sound wave reflection reducing material 1. The waveform obtained by receiving the sound wave transmitted from the wave transmitter A by the wave receiver B with and without the sound wave reflection reducing material 1 between the wave transmitters and receivers is digital oscilloscope C.
And the time difference Δt of each waveform was measured. The propagation velocity c of the sound wave reflection reducing material 1 was obtained by the following equation (1).

C = 1 / (Δt / x + 1 / c _w ) ... (1) where x is the thickness of the sound wave reflection reducing material 1, and c _w is the propagation velocity of the propagation medium.

The results are shown in FIG. However, the horizontal axis represents frequency and the vertical axis represents propagation velocity (m / s). Measurement of Reflection Reduction Effect Two types of sound wave reflection reducing materials 1 having a thickness of 12 mm and a length and width of 100 mm were manufactured from the above resin compositions M ₁ and M ₄ .

These two kinds of sound wave reflection reducing materials 1 were attached to steel plates each having a thickness of 16 mm and a length and width of 100 mm by plastic screws to obtain a sample 5. This specimen 5
Was placed in the propagation medium as shown in FIG. 3, and the receiver D and the transmitter E were placed in this order on the central axis zz of the sample 5.
Then, the reflected wave from the sample 5 for the sound wave transmitted from the wave transmitter E is received by the wave receiver D, and the sensitivity product ATT1 (d
B) was measured. Further, instead of the sample 5, the sensitivity product ATT2 (dB) of the reflected wave of only the steel plate was measured. The reflection reducing effect ER (dB) of the sound wave reflection reducing material 1 was obtained by the following equation (2).

ER =-(ATT1-ATT2) (2) The results are shown in FIG. However, the horizontal axis is the frequency and the vertical axis is the reflection reduction effect (dB).

As can be seen from FIG. 4, the resin composition contains both the high specific gravity filler and the low specific gravity filler, and even in the case of a thick sample shape having a thickness of 25 mm, the compounding amount of the microballoon is By adjusting, it is possible to obtain a sound wave reflection reducing material having a desired propagation velocity.

On the other hand, as is apparent from FIG. 5, the specific acoustic impedance (ρc) of the sound wave reflection reducing material is such that the resin composition M ₁ containing the high specific gravity filler does not contain the high specific gravity filler. Compared with the resin composition M ₄ , it is closer to the specific acoustic impedance of the propagation medium and exhibits higher reflection reduction performance in the high frequency band. Further, the measurement result of the composition M ₁ is in good agreement with the design calculation value S of the model in which the uniform material is used, and it is clear that the filler is uniformly dispersed in the sound wave reflection reducing material.

[0029]

As described above, according to the present invention, a reaction-curable resin that brings the filler into a non-fluid state within 30 seconds from the start of the reaction is a low specific gravity filler having a specific gravity of 0.01-0.10. Since the high specific gravity filler having a specific gravity of 2 to 10 is dispersed, by uniformly mixing the low specific gravity filler and the high specific gravity filler in the reaction curable resin, the low specific gravity in the acoustic reflection reducing material after the curing reaction is reduced. It is possible to uniformly disperse the filler and the high specific gravity filler. Therefore, even if the sound wave reflection reducing material is thick, it is possible to obtain the specific gravity as designed by the composition, and it is possible to accurately manufacture the material having the propagation constant and the density necessary for the acoustic design.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing an example of a sound wave reflection reducing material of the present invention.

FIG. 2 is an explanatory diagram showing a measurement test of a propagation velocity of the sound wave reflection reducing material of FIG.

FIG. 3 is an explanatory diagram showing a measurement test of a reflection reducing effect of the sound wave reflection reducing material of FIG.

FIG. 4 is a graph showing the measurement result of the propagation velocity of the sound wave reflection reducing material of FIG.

5 is a graph showing the measurement results of the reflection reduction effect of the sound wave reflection reducing material of FIG.

[Explanation of symbols]

1 Sound wave reflection reducing material 2 Reaction curable resin 3 Micro balloon (low specific gravity filler) 4 Granules (high specific gravity filler) 5 Specimen A wave transmitter B receiver C oscilloscope D receiver E wave transmitter

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁷ Identification symbol FI F16F 9/30 F16F 9/30 (72) Inventor ▲ Naoki Takagaki 2-1, Oiwake, Hiratsuka-shi, Kanagawa Yokohama Rubber Co., Ltd. Hiratsuka (56) References JP 2000-198941 (JP, A) JP 7-90119 (JP, A) JP 7-62054 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) C08L 1/00-101/16 C08K 3/00-13/08 E04B 1/86 F16F 9/30

Claims (4)

(57) [Claims] 1. A reaction-curable resin that brings the filler into a non-fluid state within 30 seconds from the start of the reaction is deformed by sound pressure.
Specific gravity 0 consisting of a micro-balloon with a wall of soft that.
A resin composition for a sound wave reflection reducing material, which is obtained by dispersing a low specific gravity filler having a specific gravity of 01 to 0.10. And a high specific gravity filler having a specific gravity of 2 to 10. 2. The viscosity of the reaction-curable resin before starting the curing reaction is 300 to 5000 mPa · s, and the viscosity for making the filler in a non-fluid state is 20000 mPa · s.
The resin composition for a sound wave reflection reducing material according to claim 1. 3. The resin composition for a sound wave reflection reducing material according to claim 1, wherein the reaction curable resin is a room temperature fast curable polyurethane. 4. A sound wave reflection reducing material obtained by curing the resin composition according to any one of claims 1 to 3.