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JPS60226300

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DESCRIPTION JPS60226300
[0001]
[Object of the invention] [Industrial field of application] The present invention relates to the
improvement of a vibrating member for an electroacoustic transducer such as a diaphragm for a
speaker, a dust cap, or a diaphragm for a center dome radiator or a microphone. The present
invention relates to a vibrating member for an electroacoustic transducer made of a material that
is very easy to use. [Prior Art] In recent years, a vibration member for an electroacoustic
transducer, for example, a diaphragm for a speaker, is considered to use carbon fiber as a
member of a diaphragm constituting material mainly for the purpose of increasing rigidity. There
is. An example of this type of diaphragm is (1) after mixing the carbon fiber and the valve fiber,
then forming the diaphragm using a phenolic resin or the like (2) mixing the carbon fiber with a
thermoplastic resin such as polypropylene resin to obtain a sheet A thermosetting resin is
impregnated into a woven or non-woven fabric of non-woven or non-woven diaphragm (3)
carbon fiber which is molded and vacuum-molded the above-mentioned material or injectionmolded the above material into a prepreg, which is press molded Vibrating plates and the like
have been put to practical use. [Problems to be Solved by the Invention] However, the abovementioned conventional diaphragm has various drawbacks. For example, in (1), the high elastic
properties characteristic of carbon fibers are not fully utilized, and even if it is mixed with 50
wt% of carbon fibers, Young's modulus is at most 5 × Q10 dyn / cm. This is because there is a
peak value in Young's modulus with respect to the mixing ratio of carbon fiber and valve fiber,
and the mixing ratio of carbon fiber is limited. In (2), the flowability at the time of sheet
formation and the size of the discharge nozzle are limited by the amount of carbon fiber mixed.
For example, in a 0.3 to 0.5 thick sheet, the amount of carbon fiber mixed is at most 20 wt%.
Moreover, the said mixing amount also receives the restriction | limiting from a vacuum forming
process. On the other hand, in injection molding, the mixing amount is at most 15 wt%.
Therefore, the rigidity of the diaphragm can not be sufficiently increased. Furthermore, in (3), a
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diaphragm with high rigidity is obtained as compared with the above two examples, but in order
to form a flat cloth once textured as a woven fabric into a cone shape or a dome shape, Since
stretching can not be expected and shaping must be performed using a weave deviation, shaping
can be performed through a number of steps such as preforming, so that the manufacturing cost
is extremely high, and a shape with a large apex angle or corrugation It was difficult to form a
diaphragm having a complicated shape such as integral molding of ribs. [Aspects of the
Invention] The present invention is a vibrating member for electro-acoustic transducer obtained
by heat-forming a composite material obtained by mixing a layered mineral in which a curing
agent or a curing accelerator is adsorbed in a gap, a thermosetting resin and an inorganic single
crystal fiber. It is.
As a layered mineral in which a curing agent or a hardening accelerator used in the present
invention is adsorbed in a space, there is, for example, montmorillonite (A1203.4 · S 102 · n H2O,
aka bentonite) which is a kind of hydrous aluminum silicate. Dilute (60 ° C., several hours) in a
solution of the curing agent or curing accelerator in a suitable solvent. As a result, a curing agent
or a curing accelerator is adsorbed between the silicate layers of montmorillonite. The solution is
washed and then dried to obtain a complex with a curing agent or curing accelerator. Next, an
embodiment of the diaphragm of the present invention using the composite will be described.
[Example] Composite (Adsorbed with diaminodiphenylmethane as curing agent) 10 parts Epoxy
resin monomer (trade name: araldite 6071) 35 parts Hardening agent (diaminodiphenyl sulfone)
4.4 parts Releasing agent (zinc stearate) 1 part SiC whisker (fiber diameter 0.1 to 1.0 μm fiber
length 50 to 200 μm) 50 parts The above composition is uniformly stirred while heating (85 °
C.), and then cooled and pulverized to a powder The composite material of Next, this composite
material was press-formed with a mold having a predetermined shape at a temperature of 160 °
C., a press pressure of 50 kg / cm 2, and a molding time of 10 minutes to obtain a diaphragm.
[Effect of the Invention] As a conventional diaphragm using the diaphragm and carbon fiber
obtained in the above embodiment [Conventional Example 1] consisting of 50 wt% of kraft valve,
35 wt% of carbon fiber and 1δ wt% of phenol resin Diaphragm [Conventional Example 2] A
diaphragm formed by mixing 15 wt% of carbon fiber with polypropylene resin and injection
molding it, and as a comparative example [comparative example] carbon short fibers
(polyacrylonitrile based, instead of the SiC whiskers in the above example) The results of
measuring the physical properties (density, Young's modulus) of a diaphragm obtained by mixing
50 parts of a fiber length of 360 μm) and obtaining a soil thickness almost the same as that of
the above example are shown in the table below. As apparent from the table, the diaphragm
according to the present invention has a remarkably large Young's modulus, as can be seen from
the table: 11 n / cm, specific modulus of elasticity: X10 dyn-cm / g. The cause of the remarkable
increase in Young's modulus of the diaphragm of the present invention is a blend in which the
montmorillonite complex is dispersed so as to fill the space of the SiC whiskers, and the epoxy
polymer and montmorillonite are firmly bonded. It is believed that shaped polymer is formed,
and the blended polymer is organized into a three-dimensional network so as to intercalate SiC
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whiskers.
In the diaphragm of the present invention, the epoxy resin once melts in the press mold and
becomes low in viscosity and flows, but the curing agent adsorbed between the montmorillonite
pots does not leach out until the constant temperature (150 ° C.) As a result of maintaining the
low viscosity flow state, it was possible to obtain a diaphragm having a high dimensional
accuracy by being filled to every corner even with a mold having a complicated shape. When
molding a conventional epoxy and curing agent mixture, curing starts immediately, so only shortterm molding can be performed, and it is difficult to fill the entire mold, and injection molding
etc. are impossible. On the other hand, according to the present invention, these drawbacks are
eliminated, and molding of the moving plate by injection molding becomes possible. In addition,
although the comparative example has a high specific elasticity as compared with the diaphragm
of the conventional example, the diaphragm of the present invention was able to further increase
the specific elastic modulus as compared with this. The reason for this is considered to be the
first point that the SiC whiskers have a larger elastic modulus and the second point that the
aspect ratio is larger when comparing SiC whiskers and carbon fibers. Further, as compared with
the comparative example, the diaphragm of the present invention has a small fiber length, and as
a result, the fluidity at the time of molding is good, so that it becomes possible to form a
diaphragm having a more complicated shape. For example, when 5 g of each material is press
molded with a flat mold at a temperature of 170 ° C. and a pressing pressure of 10 tons, how
much the material spreads is determined. In the comparative example, it remained in the shape
of about 120 mm in diameter in the comparative example. Although the present invention has
been described as the example using SiC whiskers as the inorganic single crystal fiber, it is of
course possible to apply various other inorganic single crystal fibers. Patent applicant Onkyo Co.,
Ltd.
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