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The present invention relates to a water repellent diaphragm used for a speaker. BACKGROUND
ART As performance generally required for a speaker diaphragm, it is light in weight and high in
Young's modulus, and low in density and suitable internal loss so that the output sound pressure
frequency characteristics of the speaker can be obtained favorably. It is to have. The higher the
Young's modulus of the diaphragm and the smaller the density, the higher the resonant
frequency of the diaphragm and the wider the piston movement area, so the frequency band of
the speaker can be broadened. Because the resonance is reduced, the frequency characteristics of
the speaker can be flattened. As a diaphragm which fulfills the above-mentioned required
performance to some extent, a diaphragm formed by paper-forming of a natural iIN subjected to
beating, a chemical fiber or a fiber material obtained by mixing these is widely manufactured.
Since such a diaphragm is manufactured by papermaking, it is weak to moisture and humidity,
and swelling due to absorption of moisture and deterioration of its performance occur. However,
recently, as in the case of outdoor use of speakers and door mounts and rear mounts in
automobiles, the usage of speakers has been expanded, and speakers exposed to water and
moisture are increasing. Accordingly, the diaphragm itself of the speaker is also required to have
water repellency, water resistance, and the like. As a conventional method for increasing the
water resistance of the diaphragm, for example, a method of applying a thermosetting resin to a
base material after paper making by coating to perform processing such as heating and pressing
to cover the main surface, There is known a method in which a substrate is impregnated with a
solution of a suitable polymer, and subjected to treatments such as drying, heating,
pressurization and the like to cover the entire surface from the main surface of the substrate to
the inside with a resin of the polymer. However, in the diaphragm subjected to the waterproofing
process of the former method of the above-mentioned conventional method, although the
waterproofness is high and the Young's modulus is large, the sound pressure frequency
characteristics are difficult to flatten because of the large density and the small internal loss.
Also, in the case of the diaphragm using the latter coating method, if the polymer solution is
impregnated and deposited until it has sufficient waterproofness, the weight of the substrate
increases and the Young's modulus decreases, and the sound pressure frequency characteristics
The efficiency always decreased with the decrease of the output level in the high range.
Furthermore, in consideration of the water resistance of the diaphragm, a method of forming the
diaphragm itself with a polymer compound such as polyethylene or polypropylene or a method
of forming the diaphragm with a metal such as aluminum or titanium is used. However, even
with these methods, the waterproofness and the water repellency of the diaphragm can be
satisfied, but in the case of the diaphragm of a polymer compound, high Young's modulus can
not be expected, and the internal loss is small even in the case of the metal diaphragm. Is difficult
to flatten the sound pressure frequency characteristics.
As described above, the conventional speaker diaphragm can not simultaneously satisfy the
physical properties as a diaphragm such as Young's modulus, density and internal loss, as well as
waterproofness and water repellency. SUMMARY OF THE INVENTION It is an object of the
present invention to provide a loudspeaker diaphragm having water resistance while having high
Young's modulus / low density and moderate internal loss. The diaphragm for a speaker
according to the present invention is made by impregnating or spraying a silicon functional
silylisocyanate compound having a Si-NGO bond onto a base material made of natural fibers,
chemical fibers or a mixture thereof, and then drying and curing it. It is characterized by
Implementation Example Hereinafter, an example of the present invention will be described
based on the attached drawings and the following table. First, as a first embodiment, a natural
fiber such as NBKP (conifer bleached kraft pulp) as a raw material is subjected to beating to
adjust the beating degree to 20 to 22 degrees SR. Thereafter, the suspension is dispersed in a
suspension in a paper making tank, and papermaking is performed using a desired diaphragm
shape, for example, a cone-shaped papermaking net, and then, in a cone-shaped mold at a
temperature of about 180 ° C. It is dried under a pressure press of about 0 kg / cm 2 to form a
substrate. Next, as a silyl isocyanate compound, for example, an alkylsilyl isocyanate compound,
Rns i (NCO> 4 n (wherein R is an alkyl group and n is 1.2 or 3). The trimedel silyl isocyanate
(CH3) 3SiNCO which is one of the above is dissolved in a thinner or the like to have a specific
gravity of 0.867 ( C.), a viscosity of 0.2. Prepare a solution of about IPS. Thereafter, the
formed substrate is dipped in the prepared solution of trimethylsilyl isocyanate to deposit the
solution on both major surfaces of the substrate. Alternatively, it may be applied and attached to
both main surfaces of the substrate by a spray gun. Thereafter, the substrate having the
trimethylsilyl isocyanate solution attached to both major surfaces is left to stand at room
temperature for drying and curing. Moreover, you may forcedly dry with a hot-air dryer about
40-50 degreeC as needed. The base material having undergone these steps is cut into a
predetermined shape to obtain the speaker diaphragm of the first embodiment. 1 and 2 are a
cross-sectional view and a partially enlarged cross-sectional view of the diaphragm 1 for a cone-
shaped speaker of the present embodiment obtained in this manner, wherein al12 such as a
valve is blocked by trimethylsilyl isocyanate 3 It shows that it is done. Next, as a second
embodiment, a stock obtained by refining a raw material obtained by adding chemical fiber such
as acrylic fiber to NBKP in the same manner as the first embodiment is uniformly dispersed in a
disintegrator, and a cone-shaped substrate And press-dried at a temperature of 180 to 200 ° C.
and a pressure of 3 to 4 kq / Cm 2.
Thereafter, trimethylsilyl isocyanate is dissolved in a thinner or the like in the same manner as in
the first embodiment, and the specific gravity is Prepare a solution of about IPs.
Thereafter, the prepared solution is applied and adhered to both main surfaces of the substrate
by a spray gun at a pressure of about 2.0 kg / crrr2. The base material having undergone these
steps is cut into a predetermined shape to obtain the speaker diaphragm of the second
embodiment. Table 1 shows the results of comparison of physical properties of the conventional
speaker diaphragm, that is, the diaphragm consisting only of the base material of this
embodiment, and the diaphragm of the first and second embodiments according to the present
invention. It can be seen from Table 1 Table 1 that the diaphragm base of the embodiment is a
diaphragm with a slight increase in density and an increase in Young's modulus and internal loss
as compared with the conventional one. Next, in order to investigate waterproofness, the
diaphragm base of the present invention was immersed in water and immersed for 24 hours and
then taken out to examine waterproofness and water repellency. As a result, no deformation of
the diaphragm itself was found, and further the diaphragm No penetration of water into the
interior was also confirmed. The water repellency is determined by the hardness of the coating
and the water of the silicon resin surface after the coating of the silicon resin of the threedimensional structure is easily provided on the base fiber by the height of the compound having
the S i -NGO bond. Is the performance obtained from the magnitude of the contact angle of the
Here, in the above example, trimethylsilyl isocyanate was used as a film, but alkoxysilane
isocyanate compound (RO) n S 1 (NGO) 4-n (where R is an alkyl group and n is 1, 2 or 3) It is.
Even when silicon functional silyl isocyanate compounds having an S 1-NGO bond such as silyl
isocyanate 5t (NCO) 4 and the like are used, their hydrolysis reaction shows the same effect as
the present example. In the above embodiment, only natural fibers and natural! Although the
base material made of a composite material of 1 m and chemical fiber has been described, a base
material made of only chemical fiber can also be applied. In addition, waterproofness can be
further improved by adding an inner surface sizing material such as urea formaldehyde resin and
styrene resin to the beating valve in the papermaking process. Further, the present invention
exhibits the same water repellent effect as that of the above-described embodiment not only in
the diaphragm but also in other speaker members such as a center cap obtained by papermaking and etching. According to the present invention, a silicon-functional silylisocyanate
compound having a Si-NGO bond is attached to a substrate obtained by forming natural mtta,
chemical 11 or a mixture thereof and dried and cured. A diaphragm having excellent
waterproofness and water resistance while maintaining the acoustic characteristics is obtained.
Brief description of the drawings
FIG. 1 is a cross-sectional view of the speaker diaphragm of the present invention, and FIG. 2 is a
partially enlarged cross-sectional view of the speaker diaphragm of the present invention.
Explanation of symbols of the main part 1 ··· · · · Diaphragm according to the present invention 2 ·
· · · · · mH