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JPH1175290

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DESCRIPTION JPH1175290
[0001]
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a
resin speaker diaphragm suitably used, for example, in a high fidelity speaker system and a
method of manufacturing the same.
[0002]
2. Description of the Related Art In general, paper has often been used as a material for a speaker
diaphragm. This is because the paper has low density and moderate specific modulus, bending
stiffness, internal loss. These physical properties are closely related to efficiency, reproduction
frequency band, distortion, and sound quality as acoustic characteristics. In the case of paper,
there are many variations in quality due to the conditions of the process of beating pulp,
papermaking, and pressing, and there is a problem that the change in sound quality is large
because the product is affected by the surrounding humidity. On the other hand, metal materials
and polymer materials are used as materials to replace paper. In the case of the metal material,
although the specific elastic modulus is high but the internal loss is small, there is a disadvantage
that the resonance at the high frequency limit frequency is sharp, but because of the high
specific elastic modulus, it is used only as a high frequency diaphragm. The polymer material has
a specific elastic modulus substantially equal to or slightly higher than that of paper, but a
material having a large internal loss is used for bass.
[0003]
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1
SUMMARY OF THE INVENTION It is an object of the present invention to provide a means for
further improving the physical properties of a polymeric diaphragm made of a polymer material
and further improving its bending rigidity in shape and obtaining a higher performance
loudspeaker diaphragm. It is an object.
[0004]
The present invention provides a material that balances the physical properties (weight, elastic
modulus, internal loss, etc.) effectively necessary for the above-mentioned purpose, and a method
for producing the same.
[0005]
A speaker diaphragm according to claim 1 of the present invention is a molding material
containing ultra-high crystalline polypropylene having a specific gravity of 0.91 or more and a
crystallinity of 70% or more. Is a speaker diaphragm formed by
[0006]
In the speaker diaphragm according to claim 2 of the present invention, the molding material
contains 70 to 90% by weight of ultrahigh-crystalline polypropylene and 10 to 30% by weight of
an inorganic filler having an average particle diameter of 0.08 to 0.2 μm.
[0007]
In the speaker diaphragm according to a third aspect of the present invention, the molding
material contains 60 to 90% by weight of ultrahigh-crystalline polypropylene and 10 to 40% by
weight of a fiber-based filler having an average fiber length of 6 mm or more.
[0008]
In the speaker diaphragm according to a fourth aspect of the present invention, the molding
material is a metal based material in which 40 to 70% by weight of ultrahigh-crystalline
polypropylene, average diameter 0.2 to 0.6 μm, and average aspect ratio 30 to 60. Or 30 to 60%
by weight of ceramic whiskers.
[0009]
In the speaker diaphragm according to claim 5 of the present invention, the molding material
contains 70 to 80% by weight of ultra-high crystalline polypropylene and 20 to 30% by weight of
a high-strength glass balloon.
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2
[0010]
In the speaker diaphragm according to claim 6 of the present invention, the molding material
contains a polymer alloy of ultra-high crystalline polypropylene and nylon.
[0011]
In a method of manufacturing a speaker diaphragm according to a seventh aspect of the present
invention, the molding material is filled in a molding die of a desired shape, a gas injection
molding method is performed, and a gas channel provided thereby has a structure of the speaker
diaphragm. It is characterized by being an upper rib.
[0012]
In a method of manufacturing a speaker diaphragm according to an eighth aspect of the present
invention, a foaming agent is added to the molding material, which is filled into a molding die of
a desired shape, and a gas injection molding method is performed. It is characterized in that the
rear speaker diaphragm has a hollow cross-sectional shape, and the inside of the speaker
diaphragm is occupied by a resin in a foamed state.
[0013]
In a method of manufacturing a speaker diaphragm according to a ninth aspect of the present
invention, the molding material and the foamable thermoplastic resin material are filled in a
molding die of a desired shape, and a multilayer injection molding method is performed, whereby
the speaker The molding material is disposed on the surface side of the diaphragm, and the
expandable thermoplastic resin material is disposed on the core side, so that the cross-section of
the speaker diaphragm after molding has a three-layer structure. It features.
[0014]
BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be
described below.
Embodiment 1
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3
The basic physical properties of polypropylene as a resin material, such as heat resistance and
stiffness, are closely related to the degree of crystallinity.
The super-high crystalline polypropylene used for the speaker diaphragm of the present
invention is a stereoregular polymerization progressed by the improvement of the polymerization
catalyst in the production process, and the degree of crystallinity is 70% as shown in Table 1
below. As a physical property of the material itself, the elastic modulus is improved by about 40%
as compared with conventional polypropylene, and the bending strength is also improved by
about 25%.
Further, in this ultra-high crystalline polypropylene, since the crystallization rate is fast, and a
uniform and fine crystal structure can be obtained, it is resistant to thermal deformation and can
realize good dimensional stability.
As a result, it is possible to obtain a speaker diaphragm having sufficient strength and internal
loss without adding a filler for changing the physical properties.
[0015]
Embodiment 2 FIG.
FIG. 4 is an explanatory view of the relationship between the particle diameter and the impact
strength of a 70% by weight of ultra-high-crystalline polypropylene and 30% by weight of
calcium carbonate (carbon carbide) used in the speaker diaphragm of the present invention. 4 (a)
is a table, and FIG. 4 (b) is a graph of FIG. 4 (a).
Usually, fillers are used to improve the mechanical properties of the main material resin.
However, it does not necessarily satisfy all the properties. For example, there is a contradictory
physical property that the impact strength is lowered if the flexural modulus is aimed high, but
the particle size of the ultrahigh crystallinity polypropylene and the particle size of the filler In
consideration of this, it is possible to improve the impact resistance strength by designing the
interparticle space distance in detail.
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4
For example, when calcium carbonate or talc, which is commonly used as an inorganic filler, is
filled at a ratio of 10 to 30% by weight to 70 to 90% by weight of ultra-high crystalline
polypropylene, with an average particle diameter of 0.08 to 0.2 μm Impact resistance can be
improved without decreasing the rate.
The speaker diaphragm comprised by using this molding material can further improve the high
physical property as a raw material of the ultra-high-crystal polypropylene as a main ingredient,
and can implement | achieve the outstanding acoustic characteristic.
[0016]
Third Embodiment
FIG. 5 is an explanatory view of characteristics by filler fiber length, and FIG. 5 (a) is a table, and
each of FIGS. 5 (b) to 5 (d) is a graph of FIG. 5 (a). Glass fibers and carbon fibers are
representative of fibrous fillers. In the past, a 3 to 6 mm chopped strand was compounded with a
resin using an extruder, but so far due to bending due to rotation of the extruder screw at the
kneading stage and bending of mold flow path during injection molding Since the filler is broken,
the fiber length is only 0.1 to 0.4 mm in the molded product, and although the flexural modulus
is improved, the impact resistance is lowered and the well-balanced physical properties are
obtained. It was hard to Various techniques have been developed to prevent fiber breakage
during molding. When the average fiber length is set to 6 mm or more by using this method,
both flexural modulus and impact strength can be greatly improved. The speaker diaphragm
comprised by using this molding material can further improve the high physical property as a
raw material of the ultra-high-crystal polypropylene as a main ingredient, and can implement |
achieve the outstanding acoustic property. According to the invention, preference is given to
using molding compositions which comprise 60 to 90% by weight of ultrahigh-crystalline
polypropylene and 10 to 40% by weight of fibrous fillers having an average fiber length of 6 mm
or more.
[0017]
Fourth Embodiment FIG. 6 is an explanatory view of the bending elastic modulus by the material
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5
of the filler, in which FIG. 6 (a) is a table and FIG. 6 (b) is a graph of FIG. 6 (a). Usually, fillers are
used to improve the mechanical properties of the main material resin. However, not all
characteristics are satisfied, and there is a contradictory physical property that, for example, if
the flexural modulus is aimed high, the impact strength is reduced. However, as described above,
it is possible to obtain desired physical property values by controlling the shape characteristics of
the filler. In order to improve the physical property value of a molded article, it is necessary to
keep the aspect ratio large in the fibrous filler, and in that sense, whiskers which are needle
crystals are often used. Metal- or ceramic-based whiskers with an average diameter of 0.2 to 0.6
μm and an average aspect ratio of 30 to 60 are extremely fine and function of interfacial
restraint effect to improve the flexural modulus from 2.5 GPa to 3.0 GPa or more on average be
able to. The speaker diaphragm comprised by using this material can further improve the high
physical property as a raw material of the ultra-high-crystal polypropylene as a main ingredient,
and can realize the outstanding acoustic property. According to the present invention, molding
comprising 40 to 70% by weight of ultra-high crystalline polypropylene and 30 to 60% by weight
of metallic or ceramic whiskers having an average diameter of 0.2 to 0.6 μm and an average
aspect ratio of 30 to 60 It is preferred to use the material.
[0018]
Embodiment 5 FIG. 7 is an explanatory view of the characteristics according to the ratio of the
glass balloon compounded to the diaphragm, in which FIG. 7 (a) is a table and FIG. 7 (b) is a
graph of FIG. 7 (a). There is a large difference between the thermal expansion coefficients of the
resin and the inorganic filler, and distortion occurs at the interface with the filler when the resin
solidifies after molding. In the case of an anisotropic filler, residual strain is unevenly distributed
inside the resin, which tends to cause deformation and warping. Glass balloons, which are
spherical fillers, have the advantages of no anisotropy, uniform residual strain, and high
dimensional stability. The high-strength glass balloon with a pressure resistance of several
hundred to one thousand kg / cm2 in injection molding is slightly heavier than that of
conventional products with a bulk specific gravity of about 0.2 to 0.4, but it is 20 to 40% by the
addition thereof Have the potential to reduce the weight of Furthermore, by the amount
increaseability by this, since the thickness of the molded product itself can be made bulkier than
ordinary products if aiming at the same weight, the bending elastic modulus is improved by 20 to
40%. The ability to increase the thickness also contributes to the bending strength and the like as
a shape effect, so that excellent performance as a speaker diaphragm can be realized. According
to the invention, preference is given to using molding compositions which comprise 70-80% by
weight of ultrahigh-crystalline polypropylene and 20-30% by weight of high-strength glass
balloons.
11-05-2019
6
[0019]
Sixth Embodiment Generally, alloying is good to increase the rigidity of high crystalline
polypropylene. In the present invention, it is preferable to use a polymer alloy of ultrahigh
crystalline polypropylene and nylon. However, ultra-high crystalline polypropylene is difficult to
obtain a uniform dispersion by mere blending with other substances. Therefore, when maleic
anhydride grafted polypropylene is added as a compatibilizer at the time of melt-kneading of
ultra-high crystalline polypropylene and nylon, and the polymer reaction of maleic anhydride
grafted polypropylene and terminal amine of nylon molecule is carried out, the graft copolymer
becomes As a result, the domain particles are finely dispersed to form a stable polymer alloy.
This polymer alloy is more rigid than polypropylene alone, so it can realize excellent
performance as a speaker diaphragm.
[0020]
Embodiment 7 FIG. 1 is a view for showing an example of a speaker diaphragm according to the
present invention. In FIG. 1, 7 is a speaker diaphragm formed by this molding method, and 7a is
a rib having a channel provided in the diaphragm. (I) is a plan view of the back surface, (ii) is a
side view, and (iii) is a cross-sectional view of the rib portion in the 8-8 ′ direction. In
conventional injection molding, the plate thickness is substantially determined by the pressure
applied to the molten resin, and the ribs provided for the purpose of enhancing the mechanical
strength of the finished product have a plate thickness which disturbs the pressure distribution
in this plane. It must be accompanied by change. Therefore, the current ribs have to be made, for
example, to be fine in order to avoid defects such as sink marks, and as described above, they are
only for making deformation of the product less likely to occur than to improve the mechanical
strength. . By arranging gas channels as shown in FIG. 1, it is possible to form a rib that is larger
in shape than in the prior art, and it is possible to improve bending rigidity as a shape effect.
Moreover, according to this method, by using gas rather than forming ribs only by the pressure
of the resin, overfilling of the resin is eliminated, and molding becomes possible at a lower
pressure, and the residual internal stress of the product can be reduced. It also contributes to the
dimensional stability of the
[0021]
Eighth Embodiment FIG. 2 is a view showing an example of a manufacturing process of the
speaker diaphragm according to the present invention. In FIG. 2, 1 is a movable side mold, 2 is a
11-05-2019
7
fixed side mold, 3 is a molding machine nozzle, 4 is a mold gate, 5 is a molten resin injected, and
6 is a space by injected gas. As shown in (i), in the molding die, the molten resin is injected from
the gate port in a smaller amount than the space of the mold cavity. Then, as shown in (ii), high
pressure nitrogen gas is injected to follow it. As is known, this method is called so-called gas
injection molding. Thus, unlike ordinary injection molding, the resin in contact with the mold
begins to solidify, creating a gas space 6 in the central part of the plate thickness under the
pressure of nitrogen gas that follows it, Since the system is made to follow the inner surface of
the mold by the gas pressure from the inside of the resin, it is possible to increase the apparent
product thickness by suppressing the occurrence of sink marks and the like. Further, when a
foaming agent is added to the molten resin to be injected in the present invention, high-pressure
gas is injected immediately after injection in a short shot state as shown in (iii) to spread the
resin over the entire mold cavity. After the surface layer is formed, the cross section of the
molded article is formed so that the expandable resin foams and fills the space in the internal
space formed by the gas by extracting the high pressure gas. Therefore, the bending rigidity
required for the speaker diaphragm is realized by increasing the apparent plate thickness, and
the space generated in the molded product is filled with the foamable resin in a foamed state to
achieve space resonance. It can be prevented.
[0022]
Embodiment 9 FIG. 3 is a view showing another example of the manufacturing process of the
speaker diaphragm according to the present invention. In FIG. 3, 1 is a movable side mold, 2 is a
fixed side mold, 3a is a molding machine nozzle for outer layer side resin, 3b is a molding
machine nozzle for inner layer side resin, 4 is a mold gate, 5a is an outer layer side molten resin,
5b is an inner layer side molten resin. As shown in (i), different resins are injection-molded into
one mold from two injection units. First, the ultra-high crystalline polypropylene material of the
present invention which is to be a skin layer, or a material mainly comprising the material is
injected. The resin first cools and solidifies the portion in contact with the mold surface. At this
time, when the foamable resin to be the core material is injected, the solidified film of the skin
layer acts as a heat insulating material, and the subsequently injected resin passes through the
inside of this protective film, and under sufficient temperature conditions Fully foam. As a result,
the molded product itself becomes a three-layer structure composed of a skin layer and a core
layer (this state is shown by (ii) in FIG. 3). Thus, it is possible to approximately double the
finished thickness of the product. As a result, the physical property value can be secured by the
outer layer side material, and the structural strength can be realized by increasing the thickness
of the product. Furthermore, since different materials are combined to form three layers and the
inner layer is foamed, there is an advantage that the internal loss can be increased. After
molding, as shown in (iii), the movable mold 1 can be moved to take out the product.
11-05-2019
8
[0023]
The speaker diaphragm according to claim 1 of the present invention is formed by molding a
molding material containing ultra-high crystalline polypropylene having a specific gravity of 0.91
or more and a crystallinity of 70% or more. Thus, the elastic modulus and the bending strength
are improved. Further, in this ultra-high crystalline polypropylene, since the crystallization rate is
fast, and a uniform and fine crystal structure can be obtained, it is resistant to thermal
deformation and can realize good dimensional stability. As a result, it is possible to obtain a
speaker diaphragm having sufficient strength and internal loss without adding a filler for
changing the physical properties.
[0024]
In the speaker diaphragm according to claim 2 of the present invention, the molding material
contains 70 to 90% by weight of ultrahigh-crystalline polypropylene and 10 to 30% by weight of
inorganic filler having an average particle size of 0.08 to 0.2 μm. The impact resistance strength
can be improved without lowering the flexural modulus, high physical properties as a material of
ultra-high-crystal polypropylene as a main ingredient can be further improved, and excellent
acoustic properties can be realized.
[0025]
In the speaker diaphragm according to claim 3 of the present invention, the molding material
contains 60 to 90% by weight of ultra-high crystalline polypropylene and 10 to 40% by weight of
a fiber based filler having an average fiber length of 6 mm or more. The impact strength can be
greatly improved, the high physical properties of the material of the ultra-high-crystal
polypropylene as a main ingredient can be further improved, and excellent acoustic
characteristics can be realized.
[0026]
In the speaker diaphragm according to a fourth aspect of the present invention, the molding
material is a metal based material in which 40 to 70% by weight of ultrahigh-crystalline
polypropylene, average diameter 0.2 to 0.6 μm, and average aspect ratio 30 to 60. Or, since 30
to 60% by weight of ceramic whisker is contained, bending elastic modulus can be greatly
improved, high physical properties as a material of ultra-high crystal polypropylene as main
ingredient can be further improved, and excellent acoustic characteristics can be realized. .
11-05-2019
9
[0027]
In the speaker diaphragm according to claim 5 of the present invention, since the molding
material contains 70 to 80% by weight of ultra-high-crystalline polypropylene and 20 to 30% by
weight of high-strength glass balloon, the amount increase is enhanced and the same weight
Since the thickness of the molded product itself can be made bulkier than ordinary products if it
is aimed at, the flexural modulus is improved.
[0028]
In the speaker diaphragm according to claim 6 of the present invention, the rigidity is
significantly improved because the molding material contains a polymer alloy of ultra-high
crystalline polypropylene and nylon.
[0029]
In a method of manufacturing a speaker diaphragm according to a seventh aspect of the present
invention, the molding material is filled in a molding die of a desired shape, a gas injection
molding method is performed, and a gas channel provided thereby has a structure of the speaker
diaphragm. As it is characterized by being an upper rib, bending strength and dimensional
stability are improved.
[0030]
In a method of manufacturing a speaker diaphragm according to an eighth aspect of the present
invention, a foaming agent is added to the molding material, which is filled into a molding die of
a desired shape, and a gas injection molding method is performed. Since the later speaker
diaphragm has a hollow cross-sectional shape, and the inside of the speaker diaphragm is
occupied by the foamed resin, the bending rigidity required for the speaker diaphragm can be
determined by the apparent thickness The space can be prevented from being resonated by
filling the space formed in the molded product in a foamed state in which the space formed in
the molded product is expanded.
[0031]
In a method of manufacturing a speaker diaphragm according to a ninth aspect of the present
invention, the molding material and the foamable thermoplastic resin material are filled in a
molding die of a desired shape, and a multilayer injection molding method is performed, whereby
the speaker The molding material is disposed on the surface side of the diaphragm, and the
expandable thermoplastic resin material is disposed on the core side, so that the cross-section of
the speaker diaphragm after molding has a three-layer structure. Because of the feature, the
structural strength can be increased and the internal loss can be increased.
11-05-2019
10
[0032]
Brief description of the drawings
[0033]
FIG. 1 is a view for showing an example of a speaker diaphragm according to the present
invention.
[0034]
FIG. 2 is a view showing an example of a manufacturing process of the speaker diaphragm
according to the present invention.
[0035]
FIG. 3 is a view showing another example of the manufacturing process of the speaker
diaphragm according to the present invention.
[0036]
FIG. 4 is an explanatory view of the relationship between the particle diameter and the impact
strength of a molding material of 70% by weight of ultrahigh-crystalline polypropylene and 30%
by weight of calcium carbonate (carbon carbide) used for the speaker diaphragm of the present
invention.
[0037]
FIG. 5 is an explanatory view of characteristics by filler fiber length.
[0038]
6 is an explanatory view of the bending elastic modulus by the material of the filler.
[0039]
FIG. 7 is an explanatory view of the characteristics by the ratio of the glass balloon compounded
to the diaphragm.
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11
[0040]
Explanation of sign
[0041]
Reference Signs List 1 movable side mold 2 fixed side mold 3 molding machine nozzle 3a outer
layer side resin molding machine nozzle 3b inner layer side resin molding machine nozzle 4 mold
gate 5 injected molten resin 5a outer layer side Melt resin, 5b inner layer melt resin, space with 6
injected gas, 7 molded speaker diaphragm, 7a rib.
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