JP3229375B2 - Underwater acoustic material - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to underwater acoustic materials,
More specifically, the present invention relates to an underwater acoustic material capable of preventing the intrusion of water into air bubbles by eliminating an adhesive interface and achieving long-term stability of acoustic performance and improvement of durability.

[0002]

2. Description of the Related Art In general, it is known that underwater acoustic materials used in water include a sound insulating material that blocks and reflects underwater sound waves and a sound absorbing material that absorbs underwater sound waves and attenuates reflected waves. Have been. The sound insulation material blocks a sound wave in water by being provided with a material that makes acoustic impedance different from water, and the sound absorbing material absorbs a sound wave in water by being provided with a material that makes acoustic impedance equal to water. are doing.

[0003] As a material for making the acoustic impedance different from or equal to that of water as described above, conventionally,
Both use air. By adjusting the amount of this air, it is used as a sound insulating material or a sound absorbing material.
By the way, as the underwater acoustic material, for example, those having a configuration as shown in FIGS. 8 and 9 are known. The underwater acoustic material of FIG. 8 has a flat plate shape, and a cover rubber layer 13 is fixed to a main rubber layer 12 containing a plurality of cavities 11 with an adhesive so as to seal the cavities 11. It is a thing.

The underwater acoustic material shown in FIG. 9 also has a plate-like shape, and a cover rubber layer 13 is formed on both sides of a main rubber layer 12 provided with a plurality of penetrating cavities 11 so as to cover the cavities 11.
a and 13b are fixed via an adhesive. In both the underwater acoustic materials, air (bubbles) is sealed in the cavity 11.

[0005]

However, in the above-mentioned underwater acoustic material, when the cover rubber layer 13 is adhered to the main rubber layer 12 with an adhesive, the adhesive pressure is insufficient and the amount of the adhesive applied is insufficient. Due to uniformity and the like, when used in water for a long period of time, water penetrates from the adhesive interface 14 between the main rubber layer 12 and the cover rubber layer 13, and the water penetrates into the hollow portion 11, so that sound insulation performance, Alternatively, there has been a problem that acoustic performance such as sound absorption performance cannot be maintained, resulting in poor durability.

The present invention has been devised in view of such a conventional problem, and prevents the intrusion of water into bubbles by eliminating an adhesive interface, thereby improving long-term stability of acoustic performance and improvement of durability. It is an object of the present invention to provide an underwater acoustic material that can be achieved.

[0007]

In order to achieve the above object, the present invention provides a flexible sheet-shaped sheet body.
An uneven cover part is provided integrally, and the seat body and the concave
Multiple cavities filled with independent air bubbles with a convex cover
An air bubble sheet that forms a cave and this air
The gist is that the upper and lower surfaces of the bubble sheet are integrally formed with a coating layer coated with a resin having flexibility and water resistance.

[0008]

According to the present invention, since the air bubble sheet having independent air bubbles is covered with a resin having flexibility and water resistance as described above, the bonding interface bonded with an adhesive or the like is eliminated. In addition, the intrusion of water into the air bubbles from the adhesive interface is completely prevented, and the air bubbles can always be kept completely independent.

[0009]

Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a partially cutaway plan view of an underwater acoustic material according to the present invention, and FIG. 2 is a partial cross-sectional view. The underwater acoustic material 1 has a flat plate shape, and a plurality of coating layers 2 made of resin. Are covered with an air bubble sheet 4 having independent air bubbles. The resin used for the coating layer 2 is a thermosetting resin having flexibility and water resistance, such as a flexible epoxy resin or a urethane resin. Further, it is preferable that the cured product has a viscosity that can be poured into a mold and the JIS hardness of the cured product is about 90 or less. When the JIS hardness exceeds about 90, the flexibility becomes poor and the acoustic performance cannot be sufficiently exhibited. The lower limit of the JIS hardness of the cured product is preferably about 40 or more in order to have sufficient hardness as an underwater acoustic material.

[0010] Still further, the heat of curing is 80 ° C or less,
The curing speed is preferably at least 24 hours at room temperature. If the curing heat exceeds 80 ° C. and the curing speed is less than 24 hours at room temperature, the air bubbles 3 of the air bubble sheet 4 cannot be maintained uniformly in the manufacturing process. In addition, the thermosetting resin, in handling,
It is preferably liquid in a temperature range of about 10 to 40 ° C. For example, as the above-mentioned resin, A to
D, and as shown in Table 2. However, Table 2 is Table 1
Indicates the trade name of the resin used in.

Table 1

Table 2 The air bubble sheet 4 is flexible and includes a sheet-shaped sheet body 4a and an uneven cover portion 4b integrally provided on the sheet body 4a as shown in FIG. Have been. Therefore, a plurality of cavities 3 are uniformly arranged and formed in the concave portion of the cover 4b, and the cavities 3 are filled with independent bubbles (air).

The seat body 4a and the cover 4b are
As shown in FIG. 4, the resin layers R1, R2 and R3 have a three-layer structure.
For the resin layers R1 and R3, a resin having heat resistance during manufacturing processing is used, and for example, a polyethylene resin is used. For the resin layer R2, a resin that prevents air permeation is used, for example, a nylon resin is used. As the air bubble sheet 4, for example, Capron # 107 [trade name: manufactured by JSP Corporation]
Etc. The air bubble sheet 4 is not limited to the above, and various modes are possible as long as the air bubbles in the formed hollow portion 3 can be maintained in the step of coating the coating layer 2.

The above-described underwater acoustic material 1 is manufactured as shown in FIG. First, a resin is mixed and defoamed so as to satisfy the above-described conditions. Next, as shown in FIG.
The mixed resin 5 thus mixed is poured into a predetermined mold 6 by a specified thickness. Subsequently, as shown in FIG. 5B, the resin 5 in the mold 6 into which the air bubble sheet 4 has been poured.
It is arranged on the top so that no air is interposed between the sheet 4 and the resin 5. Then, the mixed resin 5 is filled on the air bubble sheet 4 of the mold 6, and the mixed resin 5 is cured to produce the underwater acoustic material 1 as shown in FIG.

As described above, according to the present invention, the flexible air bubble sheet 4 having a plurality of independent bubbles is covered with the covering layer 2 made of a resin having flexibility and water resistance, and is integrally formed. As a result, the adhesive interface is eliminated, water is prevented from entering the cavity 3 from the adhesive interface, and the long-term stability and durability of the acoustic performance of the underwater acoustic material 1 can be improved. Further, since the pressure resistance is improved, there is an advantage that a change in acoustic performance due to a change in pressure is small.

In the underwater acoustic material 1 described above, an example is described in which the air bubble sheet 4 is provided in a single stage in the thickness direction. However, the air bubble sheet 4 may be arranged in two or three stages depending on the application. The manufacturing method in this case can also be manufactured by alternately disposing the mixed resin and the air bubble sheet in the mold. Next, an acoustic performance (transmission loss TL [transmission loss]) measurement test of the underwater acoustic material 1 prototyped by the method described above using a resin having the compounding ratio and characteristics shown in A of Table 1 as the coating layer 2 was described. explain.

[0017] Thickness 12mm, length and width each 300mm
The underwater acoustic material 1 having a porosity of about 33% was prepared using the capron # 107 as the air bubble sheet 4 (cured at 20 ° C. for 24 hours). After attaching a 3.2 mm iron plate to the receiver B side of the underwater acoustic material 1 with an adhesive, FIG.
As shown in the figure, the acoustic wave transmitter A and the acoustic wave receiver B are placed in water H at a depth of 0.5 m, and
m and 1 mm were arranged so as to face each other with the underwater acoustic material 1 interposed therebetween, and the difference between the received sound pressure levels when the underwater acoustic material 1 was present between the transceivers A and B and when they were not present was measured.

The result is shown by a solid line in FIG. Here, the horizontal axis is frequency (kHz) and the vertical axis is transmission loss (dB).
For reference, chloroprene rubber is used as a material, and has a thickness of 13 mm, a length and width of 300 mm, and a porosity of about 33 mm.
The acoustic performance of the conventional underwater acoustic material (conventional example) is also shown by a broken line in FIG. As is clear from FIG. 7, the embodiment of the present invention has almost the same acoustic performance as the conventional one.
Therefore, since the underwater acoustic material of the present invention does not have an adhesive interface even when used for a long period of time, water does not enter the air bubbles from the adhesive interface, and thus, the acoustic performance can be maintained for a long time. It is easily speculated that this is possible.

[0019]

As described above, the present invention has flexibility.
The uneven cover is integrated on the sheet-like sheet body
And the sheet body and the uneven cover are independent
Air forming multiple cavities filled with air bubbles
-Air bubble sheet and a coating layer in which the upper and lower surfaces of the air bubble sheet are coated with a resin having flexibility and water resistance are integrally formed. There is an effect that the infiltration of water is completely eliminated, the long-term stability of acoustic performance and the durability are improved, and the life of the underwater acoustic material can be maintained long. Further, since the pressure resistance is improved, there is an advantage that the change in acoustic performance due to the pressure change is small.

[Brief description of the drawings]

FIG. 1 is a partially cutaway plan view of an underwater acoustic material according to the present invention.

FIG. 2 is a sectional view of an underwater acoustic member.

FIG. 3 is a sectional view of an air bubble sheet.

FIG. 4 is an enlarged partial cross-sectional view of the air bubble sheet.

FIG. 5 is an explanatory view showing a method for producing an underwater acoustic material.

FIG. 6 is an explanatory diagram of a transmission loss measurement test.

FIG. 7 is a graph showing the results of a transmission loss measurement test.

FIG. 8 is a cross-sectional view of a conventional underwater acoustic material.

FIG. 9 is a sectional view of a conventional underwater acoustic material.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Underwater acoustic material 2 Coating layer 3 Cavity part 4 Air bubble sheet

Claims (1)

(57) [Claims] 1. On a sheet-shaped sheet body having flexibility.
An uneven cover portion is provided integrally with the seat body.
Multiple bubbles with independent air bubbles enclosed by an uneven cover
An air bubble sheet that forms a cavity and this air
An underwater acoustic material comprising integrally formed upper and lower surfaces of a bubble sheet and a coating layer coated with a resin having flexibility and water resistance.