JPH0643879

Patent Translate
Powered by EPO and Google
Notice
This translation is machine-generated. It cannot be guaranteed that it is intelligible, accurate,
complete, reliable or fit for specific purposes. Critical decisions, such as commercially relevant or
financial decisions, should not be based on machine-translation output.
DESCRIPTION JPH0643879
[0001]
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to
underwater acoustic materials, and more particularly, to eliminate the adhesive interface to
prevent the entry of water into bubbles, and to improve the long-term stability of acoustic
performance and the durability. Relates to an underwater acoustic material that can
[0002]
2. Description of the Related Art Generally, it is known that underwater acoustic materials used in
water include a sound insulating material that blocks and reflects sound waves in water and a
sound absorbing material that absorbs sound waves in water and attenuates reflected waves. It is
done. The sound insulation material blocks sound waves in water by providing a material that
makes the acoustic impedance different from that of water, and the sound absorbing material
absorbs sound waves in the water by having a material that makes the acoustic impedance of
water equal. doing.
[0003]
As a substance which makes the acoustic impedance different from the water mentioned above,
or a substance which makes the same, air is conventionally used together. By adjusting the
amount of air, it is used as a sound insulation material or sound absorption material. By the way,
04-05-2019
1
as said underwater acoustic material, the thing of a structure as shown, for example in FIG.8 and
FIG.9 is known. The underwater acoustic material of FIG. 8 has a flat plate shape, and the cover
rubber layer 13 is fixed to the main rubber layer 12 containing a plurality of hollow portions 11
with an adhesive so as to seal the hollow portions 11. It is
[0004]
The underwater acoustic material of FIG. 9 also has a flat plate shape, and cover rubber layers
13a and 13b are adhered on both sides of the main rubber layer 12 provided with a plurality of
penetrating cavities 11 so as to cover the cavities 11. It is fixed via an agent. Air (bubbles) is
enclosed in the cavity 11 for both underwater acoustic materials.
[0005]
However, in the case of the above-mentioned underwater acoustic material, when the cover
rubber layer 13 is attached to the main rubber layer 12 with an adhesive, the adhesive pressure
is insufficient and the amount of the adhesive applied is not sufficient. When used in water for a
long time due to uniformity etc., water infiltrates from the adhesive interface 14 between the
main rubber layer 12 and the cover rubber layer 13, and the water also infiltrates the hollow
portion 11, resulting in sound insulation performance, Alternatively, there is a problem that the
acoustic performance such as the sound absorption performance can not be maintained, and the
durability is inferior.
[0006]
The present invention has been devised focusing on such conventional problems, and it is
possible to prevent water from entering the air bubbles by eliminating the adhesive interface,
and to improve long-term stability and durability of the acoustic performance. It is an object of
the present invention to provide a possible underwater acoustic material.
[0007]
SUMMARY OF THE INVENTION In order to achieve the above object, the present invention
covers a flexible air bubble sheet having a plurality of independent cells and a covering layer of a
resin having flexibility and water resistance. The gist of the invention is that it is integrally
configured.
[0008]
04-05-2019
2
The present invention is configured as described above, and since the air bubble sheet having
independent cells is covered with the resin having flexibility and water resistance, the adhesive
interface adhered by the adhesive or the like is excluded. The entry of water from the adhesive
interface into the air bubbles is completely prevented, and the air bubbles can be always kept
completely independent.
[0009]
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment of the present
invention will now be described with reference to the attached drawings.
FIG. 1 is a partially cutaway plan view of the underwater acoustic material according to the
present invention, and FIG. 2 is a partial cross-sectional view. This underwater acoustic material
1 has a flat plate shape and a plurality of covering layers 2 made of resin. The air bubble sheet 4
having independent air bubbles is coated integrally.
The resin used for the covering layer 2 is a thermosetting resin, which has flexibility and water
resistance, and is, for example, a flexible epoxy resin, a urethane resin or the like.
Moreover, it is preferable to have a viscosity which can be cast in a mold, and the JIS hardness of
the cured product is about 90 or less.
When the JIS hardness exceeds about 90, the flexibility is poor and the acoustic performance can
not 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]
Furthermore, it is preferable that the curing heat is 80 ° C. or less and the curing rate is 24
hours or more at normal temperature. If the curing heat is over 80 ° C. and the curing rate is
less than 24 hours at normal temperature, the air bubbles 3 possessed by the air bubble sheet 4
can not be uniformly maintained in the manufacturing process. Further, the thermosetting resin
04-05-2019
3
is preferably liquid in a temperature range of about 10 to 40 ° C. in handling. For example, as
resin mentioned above, it is as shown in AD of Table 1 below, and Table 2. However, Table 2
shows trade names of resins used in Table 1.
[0011]
Table 1
[0012]
The air bubble sheet 4 has flexibility, and as shown in FIG. 3, a sheet-like sheet main body 4a and
an uneven cover portion 4b integrally provided on the sheet main body 4a. It consists of
Therefore, a plurality of hollow portions 3 are uniformly arranged and formed in the concave
portion of the cover portion 4b, and air bubbles (air) independent of each other are sealed in the
hollow portions 3.
[0013]
The sheet main body 4a and the cover portion 4b are both composed of resin layers R1, R2 and
R3 having a three-layer structure as shown in FIG. 4, and the resin layers R1 and R3 have heat
resistance in manufacturing and processing. Resins are used, for example polyethylene resins.
Moreover, resin which prevents air permeation is used for resin layer R2, for example, nylon
resin is used. Examples of the air bubble sheet 4 include Capron # 107 (trade name:
manufactured by JSP Co., Ltd.). If the air bubble sheet 4 can maintain the air bubbles in the
formed cavity 3 in the step of covering the covering layer 2, various aspects are possible without
being limited to the above.
[0014]
The above-mentioned underwater acoustic material 1 is manufactured as shown in FIG. First, the
resin is mixed and degassed so as to meet the conditions described above. Next, as shown in FIG.
5A, the mixed resin 5 mixed is poured into a predetermined mold 6 with a specified thickness.
Subsequently, as shown in FIG. 5B, the air bubble sheet 4 is placed on the resin 5 in the mold 6
04-05-2019
4
into which the air bubble sheet 4 is poured so that air does not intervene 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.
[0015]
As described above, according to the present invention, since the flexible air bubble sheet 4
having a plurality of independent air bubbles is covered with the covering layer 2 made of the
resin having flexibility and water resistance, it is integrally configured. The adhesive interface is
eliminated, the infiltration of water from the adhesive interface into the cavity 3 is prevented, and
the long-term stability and the durability of the acoustic performance of the underwater acoustic
material 1 can be improved. In addition, since the pressure resistance property is improved, there
is an advantage that the change in acoustic performance accompanying the pressure change is
small.
[0016]
In addition, although the example which provides the air bubble sheet 4 in single step in the
thickness direction was demonstrated in the underwater acoustic material 1 mentioned above,
you may arrange in 2 steps or 3 steps according to a use, and the manufacture in that case The
method can also be manufactured by alternately arranging the mixed resin and the air bubble
sheet in the mold. Next, about the acoustic performance (transmission loss TL (transmission
loss)) measurement test of the underwater acoustic material 1 manufactured by the method
described above using the resin having the compounding ratio and characteristics shown in A of
Table 1 as the coating layer 2 explain.
[0017]
The underwater acoustic material 1 having a thickness of 12 mm and each of 300 mm in length
and width, and using Capron # 107 as the air bubble sheet 4 and having a porosity of about 33%
was produced (cured for 24 hours at 20 ° C.). After attaching an iron plate of 3.2 mm to the
receiver B side of the underwater acoustic material 1 with an adhesive, as shown in FIG. 6, the
iron plate is placed in water H at a water depth of 0.5 m, the acoustic wave transmitter A and the
acoustic wave The receiver B is arranged to face the receiver B via the 2 m and 1 mm underwater
acoustic materials 1 respectively, and the received sound pressure with and without the
04-05-2019
5
underwater acoustic material 1 between the transceivers A and B. The level difference was
measured.
[0018]
The result is shown by a solid line in FIG. However, the horizontal axis is frequency (kHz) and the
vertical axis is transmission loss (dB). Further, as a reference, the acoustic performance of a
conventional underwater acoustic material (conventional example) having chloroprene rubber as
a material and having a thickness of 13 mm, each of 300 mm in length and width, and a porosity
of about 33% is also shown in FIG. As apparent from FIG. 7, it can be seen that the embodiment
of the present invention has substantially the same acoustic performance as that of the prior art.
Therefore, since the underwater acoustic material of the present invention does not have an
adhesive interface even in long-term use, there is no penetration of water from the adhesive
interface into the air bubbles, thus maintaining acoustic performance over a long period of time.
It is easily guessed that it is possible.
[0019]
As described above, according to the present invention, a flexible air bubble sheet having a
plurality of independent cells is integrally covered with a covering layer made of a resin having
flexibility and water resistance. Therefore, it is possible to completely eliminate the infiltration of
water from the adhesive interface into the air bubbles, to improve the long-term stability and the
durability of the acoustic performance, and to keep the life of the underwater acoustic material
long. In addition, since the pressure resistance characteristics are improved, there is an
advantage that the change in acoustic performance accompanying the pressure change is small.
04-05-2019
6