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JPH07307993

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DESCRIPTION JPH07307993
[0001]
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an
underwater transmitter and receiver protective container for containing a transmitter and a
receiver used in water, and a method of manufacturing the same. Underwater transmitter
protection intended to keep the “IL level” as low as possible, especially for use in high
frequency bands such as several tens KHz to 100 KHz or 100 KHz to 400 KHz The present
invention relates to a container and a method of manufacturing the same.
[0002]
2. Description of the Related Art Conventionally, when searching for an object in water, a
transducer is attached to the bottom of the ship to receive and analyze the reflected sound of the
sound wave from the target object and the sound wave generated by the object. The method to
judge by that is adopted. Such a transducer is housed in a protective container and attached to
the bottom of the vessel for the purpose of avoiding contact with obstacles such as driftwood
during navigation of the vessel and suppressing noise generated by navigation.
[0003]
Also, as a conventional protective container, a container body is made of steel, a rubber material
in which a steel wire is embedded as a reinforcing material, or a reinforcing layer made of
reinforcing fibers is embedded in a resin container body. Things are known.
04-05-2019
1
[0004]
However, the container body for housing the conventional transducer as described above is a
steel when used in high frequency bands such as several tens of KHz to 100 KHz or 100 to 400
KHz. In the case of a rubber protective container made of steel wire or steel wire, there is a
problem that "IL level" becomes large and can not be used.
[0005]
In addition, although it is possible to minimize the “IL level” in the required frequency band by
controlling the wall thickness of the protective container made of resin, when a specific sound
wave incident angle is reached, the vicinity of that angle In some cases, it has been difficult to
detect and detect objects in water, because the "IL level" is rapidly increased.
The present inventors conducted various studies in order to solve such conventional problems,
and as a result, a specific treatment was applied to aramid fibers and embedded in rubber by a
specific method, so that the “IL level” was a conventional method. It has been found through
various experiments that the present invention can be significantly improved as compared with
the above.
[0006]
The present invention was devised focusing on such conventional problems, and it is possible to
suppress the "IL level" to a low level even when the frequency band used is a high frequency
band such as several tens KHz to 100 KHz or 100 KHz to 400 KHz. It is an object of the present
invention to provide an underwater transmitter-receiver protective container and a method of
manufacturing the same.
Another object of the present invention is to provide an underwater transmitter-receiver
protective container capable of suppressing the "IL level" to a low level even when the incident
angle of a sound wave is large in a high frequency band and a method of manufacturing the
same. is there.
[0007]
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Another object of the present invention is to provide an underwater transmitter-receiver
protective container having a predetermined strength under use conditions and capable of
reducing the weight of the container itself and a method of manufacturing the same.
[0008]
SUMMARY OF THE INVENTION In order to achieve the above object, the present invention is
characterized in that a reinforcing layer formed of a reinforcing cord made of aramid fiber is
embedded in a container body made of a rubber material.
The rubber material of the protective container is preferably made of a chloroprene rubber
composition, and the underwater transmitter-receiver protective container is a reinforcement
made of an aramid fiber in which a rubber component is impregnated and attached to a
container main body made of a rubber material. The reinforcement layer formed of cords is
embedded and used particularly in a high frequency band around 100 to 400 KHz.
[0009]
Preferably, the aramid fiber consists essentially of poly-p-phenylene terephthalamide fiber.
Furthermore, the aramid fibers of the reinforcing layer are embedded substantially parallel so
that the ratio (d0 / d1) of the cord diameter (d0) / cord interval (d1) is 0.15 to 1.3. The overall
thickness including the reinforcing layer of the container main body is preferably 15 mm or less
and 3 mm or more.
[0010]
The present invention is configured as described above, and the reinforcing cord comprising the
aramid fiber is embedded in the rubber material forming the container main body in the step
prior to embedding the reinforcing layer formed by the reinforcing cord comprising the aramid
fiber. Treated with a mixture of the epoxy resin solid content (E) and the rubber solid content (L)
at a mixing ratio such that the weight ratio (E / L) is 1/2 to 1/15, and The working frequency is
achieved by forming a reinforcing layer in which the rubber solid content is impregnated and
deposited by 2 to 15% by weight with respect to the weight of the aramid fiber, and embedding
the reinforcing layer in the rubber material to integrally form the container body. Even if the
frequency band is as high as several tens of KHz to 100 KHz or 100 KHz to 400 KHz, the “IL
level” can be suppressed low, and even if the incident angle of the sound wave is large in the
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high frequency band, the “IL One in which it is possible to suppress Le "a low.
[0011]
Here, a rubber material, in particular chloroprene rubber, is more preferable as a material
constituting the container main body, because rubber has an intrinsic acoustic impedance closest
to water, so that it is difficult for acoustic reflection and the like to occur.
That is, when a resin material is used for the container main body, there is a problem that the "IL
level" with respect to oblique incident sound waves increases as in the prior art.
[0012]
Further, the rubber material is not particularly limited, and it is also possible to use natural
rubber, styrene butadiene rubber, butadiene rubber, isoprene rubber, chloroprene rubber,
ethylene propylene diene copolymer rubber, or a mixture thereof. In addition, chloroprene
rubber is preferable from the viewpoint of weather resistance, oil resistance, ozone resistance,
and the like when used in ships.
[0013]
The reinforcing layer in which the reinforcing cord made of aramid fiber is embedded is used
when the reinforcing container other than aramid fiber, for example, nylon or polyester fiber is
applied to the protective container of the present invention, when the internal pressure is loaded
in the container. This is because there is a problem that the container volume is increased and
the running resistance of the vessel is increased because the fiber extension is large.
[0014]
There is also a method of increasing the amount of fiber used to suppress the volume change, but
when the amount of fiber used is increased, the "IL level" is unfavorably deteriorated.
It is also conceivable to use reinforcing cords with high tensile strength and low elongation, such
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as glass fibers and steel cords, but these materials reflect incident sound waves because their
specific gravity is higher than that of rubber. As a result, the deterioration of "IL level" is
remarkable.
[0015]
Furthermore, although it is conceivable to use a lightweight, high tensile strength carbon fiber,
the use of carbon fiber has the advantage that the “IL level” in the high frequency band is
small. However, carbon fiber is poor in bending fatigue resistance that it is easily broken by
bending, etc., and when it is used for products such as rubber containers that are susceptible to
deformation, there is a problem that its durable life is greatly reduced. I could not
[0016]
On the other hand, since aramid fibers are light in weight, high in strength, and small in
elongation, the volume change of the protective container as described above is small, and the
amount of fibers used can also be reduced. Furthermore, the "IL level" in the high frequency band
is significantly improved compared to steel cords and glass fibers. Therefore, in the present
invention, it is essential to use a reinforcing cord made of aramid fiber as the reinforcing layer.
[0017]
Further, the reinforcing cord made of the aramid fiber is made of an epoxy resin solid content (E)
and a rubber solid content in the previous step of embedding the reinforcing layer formed of the
reinforcing cord made of aramid fiber in the rubber material constituting the container body.
Treat with a mixed solution mixed at a blending ratio such that the weight ratio (E / L) to (L) is
1/2 to 1/15, and the rubber solid content thereof is 2 with respect to the weight of the aramid
fiber The formation of a 15% by weight impregnated and adhered reinforcing layer and the
embedding of the reinforcing layer in the rubber material to integrally form the container body is
performed for the following reasons.
[0018]
That is, usually, in order to embed and integrate an aramid fiber in a rubber, an adhesion
treatment of the fiber and the rubber is required.
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Generally, in order to bond aramid fibers to rubber, the solution is dipped in a solution of epoxy
resin and then subjected to dry heat treatment, and then dipped in so-called RFL which is a mixed
solution of resorcinol formalin initial condensate and rubber latex It is known to perform dry
heat treatment.
[0019]
By using such a treatment method, sufficient adhesion between the rubber and the aramid fiber
necessary for the application of the present invention can be obtained, and by embedding such a
treated cord in the rubber, several tens of KHz to 100 KHz The “IL level” is a significant
improvement over conventional steel cord embedded rubber containers, but for higher frequency
bands from 100 KHz to 400 KHz the rubber content should be pre-embedded prior to
embedding in the rubber. It is preferred to use the impregnated and deposited aramid fiber cord.
[0020]
The present inventors conducted various analyzes to achieve excellent "IL levels" in the higher
frequency band from 100 KHz to 400 KHz, and in particular in the high frequency band as
described above, interfilament filaments of the aramid fiber cord. It was confirmed that the
incident sound was reflected by the air layer present in the minute air gap inherent in the to
cause an acoustic transmission loss.
[0021]
As a result of conducting various examinations in order to solve such a problem, when treating
an aramid fiber cord with an epoxy resin solution, the aramid using a mixed solution having a
specific composition in which a rubber component is dissolved in the epoxy resin solution By
impregnating and adhering a predetermined amount of rubber to fibers, it has been found that
the "IL level" is dramatically improved while maintaining adhesion with rubber.
[0022]
As the epoxy resin used here, it is possible to use a water-dispersed product such as a known
water-soluble epoxy resin or a bisphenol A-type epoxy resin, or a solution dissolved in an organic
solvent. From the viewpoint, it is more preferable to use an aqueous solution of a water-soluble
epoxy resin.
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The rubber component may be used by dissolving natural rubber, SBR, IR, BR, CR, EPDM, etc. in
an organic solvent and mixing it with a solution of an epoxy resin diluted with an organic solvent,
but like the epoxy resin From the viewpoint of safety and hygiene, rubber latex (water dispersion
of rubber) is preferably used.
[0023]
As the rubber latex, vinylpyridine-styrene-butadiene terpolymer rubber latex, styrene-butadiene
copolymer rubber latex, chloroprene rubber latex, natural rubber latex are used, but from the
viewpoint of the effect of improving IL level, vinylpyridine-styrene-butadiene terpolymer It is
more preferable to use a rubber latex.
In addition to this, a crosslinking agent such as blocked isocyanate may be added.
[0024]
In addition, the mixing ratio of epoxy resin and rubber mixture used in treating aramid fiber
cords is that the weight ratio of epoxy resin solid content (E) to rubber solid content (L) is 1/2 to
1/15. It is preferred that a range be used and that the impregnated weight percent of rubber
solids with respect to the weight of the aramid fiber be in the range of 2 to 15%.
When the mixing ratio of the mixed solution used for the impregnation treatment is less than 2
parts of rubber solid content to 1 part of epoxy, when 2% to 15% of the rubber component is
impregnated and adhered, the epoxy resin to the aramid fiber As a result of the adhesion ratio
also increasing, not only the aramid fiber cord becomes hard but also the "IL level" gets worse.
[0025]
On the other hand, when the mixing ratio is 1 part of epoxy and the rubber solid content is more
than 15 parts, the amount of epoxy adhering to the aramid fiber decreases when 2% to 15% of
the rubber component is impregnated and adhered. Not only does the adhesion with the rubber
decrease, but defects in the adhesion interface with the rubber also result in the deterioration of
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the "IL level". Moreover, even if it is treated with a mixed solution having a blending ratio within
the scope of the present invention, if the impregnated adhesion amount of the rubber component
is less than 2%, the air present in the aramid fiber cord increases and the "IL level" is deteriorated
Do. On the other hand, in the case of more than 15%, the adhesion is too much, so the drying is
insufficient and air bubbles are generated inside the adhered rubber component, and the “IL
level” is deteriorated. The range of the adhesion amount is more preferably 3 to 10%.
[0026]
The amount of impregnated adhesion of the aramid fibers of rubber is appropriately adjusted by
the concentration of the treatment liquid and the throttling, blow, vacuum, etc. after the
treatment. Thus, the aramid fiber cord to which a predetermined amount of rubber has been
attached is subjected to a heat treatment through a drying process for removing moisture or a
solvent. The heat treatment temperature and time are not particularly limited, but heat treatment
is performed at 180 ° C. to 250 ° C. for about 30 seconds to 2 minutes. Furthermore, although
it processes by well-known RFL for the purpose of adhesion | attachment with rubber | gum, it is
also possible to use a commercially available adhesive agent etc. In the case of treatment with
RFL, the same heat treatment as described above is applied after drying.
[0027]
It is preferred that the aramid fibers consist essentially of poly-p-phenylene terephthalamide
fibers for the following reasons. Dupont Kevlar substantially consisting of poly-p-phenylene
terephthalamide fiber as aramid fiber, twaron manufactured by Akzo Co., and a copolymer of pphenylene diamine, 3,4'-diaminodiphenyl ether and terephthalic acid chloride Teijin Ltd.
Technora is commercially available.
[0028]
Each fiber has a strength of 20 g / d or more, a small elongation and flexibility, and a low "IL
level" in a high frequency band, which is suitable as the reinforcing cord of the present invention,
but in particular from the oblique direction Poly-p-phenylene terephthalamide fibers are superior
in that they exhibit a low "IL level" with respect to incident sound waves. Also, as a reinforcing
layer in which the aramid fibers are embedded, the ratio (d0 / d1) of the cord diameter (d0) of
the embedded aramid fiber cords to the cord interval (d1) is 0.15 to 1.3. The reason why it is
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preferable to use a reinforcing layer in which the aramid fiber cords are embedded substantially
parallel to each other is that when the (d0 / d1) ratio is more than 1.30, the "IL level" increases,
especially 100 KHz. This is because an underwater transmitter / receiver protective container in
which the "IL level" in the high frequency band at -400 KHz is low can not be obtained.
[0029]
Further, when the (d0 / d1) ratio is less than 0.15, not only the improvement of "IL level" can not
be obtained any more but also the strength of the reinforcing layer is lowered and the strength
as the container becomes insufficient and protection It is because the function as a container can
not be fulfilled. The ratio (d0 / d1) is more preferably 0.20 to 0.80 in consideration of the
balance between the "IL level" in the high frequency band at 100 KHz to 400 KHz and the
strength of the protective container. The relationship between the cord diameter (d0) of the
reinforcing layer and the cord interval (d1) is as shown in FIG.
[0030]
Also, the whole thickness including the reinforcement layer of the container body is preferably
15 mm or less, preferably 3 mm or more, because the “IL level” increases when the thickness
of the container is more than 15 mm, On the other hand, if it is less than 3 mm, there is a high
possibility of being easily damaged by the impact of a driftwood or the like when used in water,
and the function as a protective container can not be achieved. The total thickness is more
preferably 10 mm to 5 mm in consideration of balance between trauma resistance and IL level.
[0031]
Next, the test method will be described. The sound transmission loss level (IL level) in the
example of the present invention was measured as follows. As shown in FIG. 1, a predetermined
number of rubber reinforcing layers 3 in which a predetermined number of reinforcing cords 3
are embedded are prepared, and these are laminated so that the reinforcing cords 3a of adjacent
reinforcing layers 3 intersect each other at right angles. A rubber layer 2 not containing fibers
was laminated to the above, and integrally processed by vulcanization was used as a test piece S.
The specimen size was 500 mm × 600 mm.
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[0032]
These test pieces S are disposed at a water depth of 1 m as shown in FIG. 2, and the transmitter X
and the receiver Y are disposed 300 mm apart from the test pieces S, respectively, and their
acoustic centerline The “IL level” of each test piece S was measured by matching the two). The
measurement frequency was 300 KHz unless otherwise noted. In addition, as a method of
making a sound wave enter from the diagonal direction, it implemented by rotating a test piece
main body. Moreover, the impregnated adhesion amount of the rubber component to the aramid
fiber cord was measured as follows.
[0033]
The weight W0 of the reinforcing cord of the untreated aramid fiber was measured in advance,
and the weight W1 of the aramid fiber cord after being treated with a mixture of epoxy resin and
rubber latex and then dried was measured. The rubber content impregnation adhesion amount
(%) can be obtained by the following equation 1. Here, (E) is solid content concentration (%) of
the epoxy resin in the liquid mixture of an epoxy resin and rubber latex. G is the solid
concentration (%) of the rubber latex in the mixture of the epoxy resin and the rubber latex.
[0034]
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The embodiments of the present
invention will be specifically described below with reference to the attached drawings. FIG. 3 is a
perspective view showing an example of the underwater transmitter-receiver protective
container 1 of the present invention. The cross-sectional view of the test piece for IL level
measurement of FIG. 1 is also an enlarged cross-sectional view of the main part in the thickness
direction of the underwater transmitter-receiver protective container of FIG. 3.
[0035]
The underwater transmitter-receiver protective container 1 is composed of a container main
body 4 in which the transmitter-receiver M can be housed, and a reinforcing layer 3 embedded in
the container main body 4. Example 1, Comparative Example 1, Conventional Example 1 As a
reinforcing cord 3a according to the present invention, manufactured by Teijin Ltd. comprising
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aramid fiber p-phenylenediamine, a copolymer of 3,4'-diaminodiphenyl ether and terephthalic
acid chloride After immersing in an aqueous solution of a water-soluble epoxy resin (Denacol EX
313: glycerol diglycidyl ether manufactured by Nagase Chemical Industries, Ltd.) using the
Technora 1500 d / 2 cord, it is dried at 120 ° C. for 1 minute and then at 230 ° C. Heat
treatment was performed for 1 minute.
[0036]
Furthermore, after being immersed in known RFL, the same dry heat treatment was performed.
Further, as a reinforcing cord of Comparative Example 1, an ECG756 / 0 cord having
substantially the same strength as the aramid fiber cord was used, and it was immersed in RFL
and subjected to the same heat treatment. Furthermore, as a reinforcing cord of Comparative
Example 1, a cord of carbon fiber 1800 d / 2 having substantially the same strength as the
aramid fiber cord is dipped in an aqueous solution of a water-soluble epoxy resin in the same
manner as aramid fiber to dry and heat treat. It was immersed and further subjected to dry heat
treatment.
[0037]
Further, as Conventional Example 1, a steel cord 1 × 5 (0.25) having substantially the same
strength as that of the aramid fiber cord was used. After these cords were aligned in parallel on a
1 mm thick rubber sheet of a chloroprene rubber composition with the number of 40 cords / 5
cm inserted, the same 1 mm thick rubber sheet was further bonded thereon to obtain a
reinforcing sheet .
[0038]
After laminating four reinforcing layers so that each crosses each other, the same rubber sheet is
bonded to both sides of the laminated material so that the total thickness is 10 mm, and then
vulcanized at 148 ° C. for 30 minutes to reinforce We made four types of laminates with
different cords. These were cut into 500 mm × 600 mm square and the sound transmission loss
was measured. Here, the incidence of the sound wave was set to be perpendicular to the
laminate. Also, the measurement frequency band is 25, 50, 75, 100, 200, 300 KHz. The results
are shown in Table 1 below.
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[0039]
As apparent from Table 1, by using aramid fiber, "IL level" at several tens KHz to 100 KHz can be
significantly improved compared to glass fiber and steel cord, and the sound transmission loss is
extremely small. Can be seen. However, in the higher frequency band above 100 KHz, the
excellent "IL level" as obtained in the frequency band below 100 KHz has not been achieved.
[0040]
On the other hand, carbon fibers, like aramid fibers, have good "IL levels" at several tens KHz to
100 KHz. However, as mentioned above, it is poor in bending fatigue resistance and application
to this application is difficult. Next, the following examples and comparative examples are
intended to illustrate the improvement of the "IL level" at 100 KHz to 400 KHz. [Example 2 to
Example 9, Comparative Example 2 to Comparative Example 6] A mixed liquid of an epoxy resin
and a rubber latex using aramid fiber cord (Kevlar manufactured by DuPont: poly-p-phenylene
terephthalamide fiber) 1500d / 2 After immersing the fibers in the fiber, the fibers are dried at
120 ° C. for 1 minute, heat-treated at 230 ° C. for 1 minute, dipped in known RFL, and
similarly dried at 120 ° C. for 1 minute Heat treatment for 1 minute.
[0041]
Here, the solid content mixing ratio of the mixed solution of the epoxy resin and the rubber latex
to be impregnated and attached to the aramid fiber cord and the adhesion amount of the rubber
component impregnated and attached to the aramid fiber were variously changed. As a method
of changing, it adjusted with the pressure of the squeeze roll after immersion and the total solid
concentration of the liquid mixture. In addition, the amount of impregnated adhesion of rubber to
the aramid fiber can be obtained by collecting the cord after drying and heat treatment after
immersion treatment with a mixture of epoxy resin and rubber latex and measuring its weight, as
described above. Calculated by the method.
[0042]
The epoxy resin used here is water-soluble glycerol diglycidyl ether (Denacol EX313
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manufactured by Nagase Kasei Co., Ltd.). The rubber latex is vinylpyridine / styrene / butadiene
polymer polymer latex (water dispersion of Nipole 2518 FS 40% solid content manufactured by
Nippon Zeon Co., Ltd.) so that both have a predetermined solid content ratio. It was dissolved in
water to make a predetermined mixture.
[0043]
In addition, water was also used for dilution to adjust the total solid concentration of the mixed
solution in order to adjust the amount of impregnated adhesion to rubber aramid fibers. Using
the fiber cord obtained in this manner, a 500 mm × 600 mm square sheet is drawn in parallel
on a rubber sheet consisting of a 0.5 mm thick chloroprene rubber composition so as to be 25
per 5 cm. Then, a 0.5 mm-thick rubber sheet was placed on the upper side of the cord to obtain a
reinforcing layer in which the cord was embedded.
[0044]
Here, the ratio of the cord diameter (d0) to the cord interval (d1) is 0.54. The three reinforcing
layers were cross-laminated so that the cords of the respective reinforcing layers were
perpendicular to each other, and then a rubber sheet made of a chloroprene rubber composition
was pressure-bonded to the front and back of the laminated material so that the total thickness
was 8 mm. . This was vulcanized using a diaphragm to make a laminated board with a cord and
used for measurement of the sound transmission loss. The sound transmission loss was such that
the incident angle of sound was perpendicular to the laminate. The measured frequency band is
300 KHz.
[0045]
In addition, as adhesion evaluation between aramid fiber and rubber, laminates whose acoustic
characteristics have been measured are cut into 25 mm width along the cord longitudinal
direction of the outermost layer, and peeling test is performed between the outermost rubber
and the outermost cord reinforcing layer Was carried out, and the rubber adhesion rate on the
bare surface was observed. Adhesion was evaluated as 100% with the best adhesion when rubber
fracture occurred on the entire surface, and 0% with adhesion failure when the cord surface was
broken. The results obtained in this way are shown in Table 2 below.
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[0046]
Table 2 shows the compounding ratio of solid content of epoxy resin (E) and solid content of
rubber (L) in a mixed solution of epoxy resin and rubber latex in which aramid fiber is immersed,
and rubber fraction impregnated and adhered to aramid fiber The wt% and “IL level” at normal
incidence measured on laminates made with these are shown.
[0048]
As described above, in order to suppress the IL level in the high frequency band such as 300 KHz
low and maintain the good adhesion with the rubber, the solid content blending ratio of the
epoxy resin and the rubber is 1/2. It is understood that it is preferable to treat the aramid fiber
with a mixed solution of 1/15 and set the impregnated adhesion amount of the rubber
component to the aramid fiber within the range of 2 to 15%.
By using the aramid fiber cord treated in this range, particularly, the sound transmission loss in
the high frequency band at 100 KHz to 300 KHz is extremely small and the adhesion to rubber is
good, and a highly durable protective container can be obtained.
[0049]
[Example 10, Comparative Example 7, Comparative Example without adhesion of rubber
component in Example 1] Poly-p-phenylene terephthalamide fiber (Kevlar manufactured by
DuPont), p-phenylene diamine, 3,4'-diamino as aramid fibers Using an aramid fiber (Technola
manufactured by Teijin Ltd.) consisting of a copolymer of diphenyl ether and terephthalic acid
chloride, the rubber is treated with a mixture of epoxy resin and rubber latex in a mixed solution
ratio of 1/10 as in Example 8. A cord with 10% of impregnated adhesion to fibers per minute was
obtained. Moreover, what was immersed in the epoxy resin aqueous solution which does not
contain a rubber component similarly to Example 1 using Teijin Technora was prepared. These
fibers were treated with RFL in the same manner as in the above example and similarly
embedded in rubber to make a laminate. The acoustic transmission loss at normal incidence and
at 40 ° oblique incidence was measured using these three types of laminates. (The frequency
band is 300 KHz) The results are shown in Table 3 below.
[0050]
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14
As described above, by using poly-p-phenylene terephthalamide among aramid fibers, it becomes
possible to provide a protective container excellent in sound transmission loss at oblique
incidence. [Examples 11 to 14 and Comparative Example 8] Three sheets are laminated in the
same manner as Example 8 using the reinforcing cord in which the ratio of the cord diameter of
the reinforcing layer to the cord interval is changed using the treated cord of Example 8. The
sound transmission loss was measured with a laminated plate having a total thickness of 8 mm
and a width of 500 mm and a length of 600 mm. The results are shown in Table 4 below.
[0052]
As described above, when the ratio of cord diameter / code interval (d0 / d1) exceeds 1.3, the [IL
level] is greatly reduced. Moreover, in the case of less than 0.15, the number of cords per 5 cm is
too small and the strength is insufficient, and it is difficult to secure the durability as a protective
container. [Examples 15-17 and Comparative Example 9] Using the treated cord of Example 8,
the number of laminated reinforcing layers was the same as in Example 8 except that the ratio
(d0 / d1) of the cord diameter of the reinforcing layer to the cord interval was also used. The
change was made to change the total thickness of the laminate. The normal incidence "IL level" at
300 KHz of these laminates was measured. The results are shown in Table 5 below.
[0053]
As described above, if the thickness exceeds 15 mm, the “IL level” rapidly deteriorates. If the
thickness is reduced, the "IL level" decreases, but if it is less than 3 mm, the body can not easily
function as a protective container because it is easily injured by an obstacle or the like.
Therefore, the total thickness is more preferably 5 mm to 10 mm from the viewpoint of trauma
resistance and the balance of "IL level".
[0054]
As described above, the underwater transmitter-receiver protective container according to the
present invention has a structure in which a reinforcing layer formed of a reinforcing cord made
of aramid fiber is embedded in a container body made of a rubber material. In the frequency
band of KHz to 100 KHz, the "IL level" can be suppressed low.
04-05-2019
15
[0055]
In addition, by using reinforcing fibers treated with a specific liquid mixture in advance and
embedded with a specific amount of rubber before embedding reinforcing fibers in rubber, and
further using an aramid fiber having a specific chemical structure, Embedding in rubber in a
specific cord diameter and cord spacing ratio, and by specifying the total thickness, to suppress
the "IL level" in the high frequency band of 100KHz to 400KHz which could not be achieved
conventionally In addition, the "IL level" against the incident sound wave from the oblique
direction, which is a drawback of the resin protective container, is also low, and it is possible to
easily manufacture a suppressed high performance underwater transmitter / receiver protective
container.
Furthermore, the underwater transmitter-receiver protective container according to the present
invention has a predetermined strength that is not easily damaged even in ship navigation and
the like, and has an effect of achieving weight reduction.
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