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JP2007143060

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DESCRIPTION JP2007143060
An object of the present invention is to improve the difference in elastic modulus and elongation
depending on the molding direction by using the excellent function of a thermoplastic elastomer.
In an acoustic diaphragm of the present invention, an edge 9 using a thermoplastic elastomer has
soft segments in which rubber particle diameter is constant and small and uniformly dispersed,
and the amount of olefin resin which is a hard segment is small Even when using a polyolefinbased elastomer having processability as the material, the radial and circumferential elongations
in which the physical properties of the material do not become anisotropic due to thin-wall
molding in injection molding have an equivalent shape of 22 It is [Selected figure] Figure 3
Acoustic diaphragm and acoustic diaphragm manufacturing method
[0001]
The present invention relates to an acoustic diaphragm having a speaker edge fixed to the outer
periphery to control the movement of a loudspeaker diaphragm, and a method of manufacturing
the acoustic diaphragm.
[0002]
Generally, in a cone type speaker, an edge formed by a rubber elastic body is fixed around the
diaphragm.
The edge needs to be braked so as not to affect the back and forth vibration transmission while
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the diaphragm is transmitting the vibration continuously, and high damping performance is
required. At the same time, it is also important that the edge be able to follow the movement of
the diaphragm, ie, high flexibility.
[0003]
Various materials are used to realize these, but the most representative is vulcanized rubber.
Vulcanized rubber is a material that is flexible and has excellent damping properties, good heat
resistance and waterproofness, and is suitable for edges. On the other hand, since it changes to
this vulcanized rubber, many edges using thermoplastic elastomer which can do sheet formation
(refer to patent documents 1) and injection molding (refer to patent documents 2) are also
developed. JP 2003-78998 JP JP 7-1318882 JP
[0004]
However, recently environmental protection measures have also tended to be emphasized, and
when vulcanized rubber is used as the edge material, it is impossible to remove residual sulfur
and to recycle materials, so it is possible to respond to environmental protection measures. There
was a disadvantage that I could not do it. In addition, since the vulcanization time is as long as 10
minutes or more in the molding step and the degree of contamination of the mold is also intense,
the manufacturing energy is high. In addition, in mass production, the number of die faces
increases to obtain the quantity, and there is a disadvantage that variation occurs in thin and
highly accurate molded articles.
[0005]
Further, in the technology using the thermoplastic elastomers described in Patent Documents 1
and 2 as the material of the edge, in reality, these thermoplastic elastomer materials are inferior
to the vulcanized rubber in vibration damping property and flexibility, so the sound quality Rated
low and many are not used. Generally, elastomers have the properties of vulcanized rubber at
ordinary temperature, but plastic deformation is possible at high temperatures, and generalpurpose molding can be performed, so they must be composed of a combination of rubber
component (soft segment) and resin component (hard segment). The former takes the form
dispersed to the latter. In the state capable of flowing at high temperature, the hard segment acts
as a fluid, and forming of the edge is performed by the hard segment entering the reverse radial
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direction from the outer peripheral direction toward the central portion in the cooled mold.
[0006]
At that time, since the melted hard segment moves in the flow direction, a surface layer
exhibiting an anisotropic orientation of the particles is formed on the surface of the edge molding
where cooling and solidification first occur. For this reason, since a remarkable orientation
appears in a reverse radial direction from the outer peripheral direction toward the central
portion, the entire formed product of the edge has a non-uniform configuration. Therefore, since
there is no elongation in the reverse radial direction which is the flow direction of the molded
article from the outer peripheral direction to the central portion where the orientation of the
edge after molding appears, flexibility is poor.
[0007]
On the other hand, a state of high flexibility can be obtained because it exhibits elongation in the
circumferential direction which is a non-flowing direction in which no orientation appears.
Therefore, articles relatively thick in molding thickness can have properties close to that of
downstream rubber, but, as required for the edge for a speaker, in thin articles having a
thickness of 0.5 mm or less, the physical effects of the acoustic effect appear It will be greatly
affected.
[0008]
The edge is generally in the form of a ring, and in the form of a roll so as to easily extend in the
radial and reverse radial directions, which are the vibration directions. However, resin flow
occurs in the reverse radial direction, which is the vibration direction that the edge after molding
is desired to extend during molding processing. For this reason, in reality, the crystallinity of the
molded product in the flow direction becomes high, and physical properties opposite to the
shape required for the edge appear. That is, in the case of the thermoplastic elastomer, there is a
problem that the elongation in the radial vibration direction is small and the sufficient rubber
function is not utilized.
[0009]
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An object of the present invention is to provide an acoustic diaphragm having an edge for a
speaker and a method of manufacturing the acoustic diaphragm, wherein the difference in elastic
modulus and elongation depending on the molding direction is improved using the excellent
function of thermoplastic elastomer. is there.
[0010]
In order to solve the above problems and achieve the object of the present invention, in the
acoustic diaphragm of the present invention, the edge using a thermoplastic elastomer has a soft
segment in which rubber particle diameter is uniformly dispersed in 1 to 10 microns. The hard
segment is made of a polyolefin-based elastomer having a processability of an olefin resin as a
material, and is formed into a shape such that the physical properties of the material do not
cause anisotropy by thin-wall molding in injection molding.
[0011]
As a result, molding of a molded product is performed by using, as an edge, an olefin-based
elastomer having a small soft rubber particle diameter and uniformly dispersed, and having
excellent processability even if the amount of hard segment olefin resin is small. When
solidifying, the ratio of the resin component in the hard segment part collected in the surface
layer of the molded product can be reduced, and the molding can be performed with a material
configuration that ensures the fluidity of the molded product.
[0012]
Further, in the method for producing an acoustic diaphragm according to the present invention, a
polyolefin-based elastomer having processability is obtained by using a soft segment in which the
rubber particle diameter is constant and small and uniformly dispersed, and the amount of olefin
resin which is a hard segment is small. The steps of filling as a material for injection of the edge
of the thermoplastic elastomer, setting the gate position for injecting the material during
injection molding to the circumferential direction of the edge, performing the injection molding,
and the step of injection molding And (d) forming an edge shape which is oriented such that the
physical properties of the material do not cause anisotropy by thin-wall molding.
[0013]
As a result, it is possible to use an olefin-based elastomer having a small rubber particle diameter
and uniformly dispersed soft segments and having excellent processability even with a small
amount of olefin resin which is a hard segment as a material for injection of the edge of
thermoplastic elastomer. By performing injection molding after setting the gate position for
filling and injecting the material in injection molding in the circumferential direction of the edge,
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the physical properties of the material do not become anisotropic due to thin-wall molding in
injection molding Since the shape of the edge to be oriented is used, it is possible to reduce the
proportion of the resin component in the hard segment part collected on the surface of the
molded product during molding and solidification of the molded product, and to secure the
flowability of the molded product.
[0014]
According to the present invention, it is possible to provide an edge for a speaker in which the
difference in elastic modulus and elongation of a molded product depending on the molding
direction can be provided by using the excellent function of the thermoplastic elastomer.
[0015]
Hereinafter, embodiments of the present invention will be described in detail using the drawings.
FIG. 1 is an explanatory view of a speaker vibration portion.
As shown in FIG. 1, the speaker vibration part is provided to constitute a speaker unit.
In FIG. 1, the cone 1 serving as the speaker diaphragm needs to be thin, light, and strong in order
to facilitate movement, and is also called internal loss to reduce peaks and valleys and transient
characteristics of frequency characteristics. It should be such as to give a modest loss.
[0016]
The center cap 2 is provided to prevent radial deformation of the cone 1 and to prevent iron
powder and dust from entering the air gap.
The center cap 2 has a hole 3 near the center, and a rough cloth 4 is attached to the hole 3.
The holes 3 function to release the air compressed and stretched by the vibration of the cone 1.
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[0017]
The coarse cloth 4 plays a dustproof function without disturbing the flow of air.
The voice coil 5 is vertically driven along the periphery of the pole 6 to vibrate the cone 1. The
damper 7 holds the voice coil 5 properly around the pole 6. Arrows 8 secure the edge 9 of the
cone 1 to the frame 10.
[0018]
Here, an edge 9 formed of a rubber elastic body is fixed around the cone 1. The edge 9 needs to
be braked so as not to affect the front and back vibration transmission while the cone 1
continuously transmits the vibration, and high damping performance is required. At the same
time, the edge 9 is also required to be able to follow the movement of the cone 1, ie, to be highly
flexible.
[0019]
Further, the edge 9 is an edge using a thermoplastic elastomer, and in this case, the ratio of the
resin component in the hard segment part collected on the surface of the molding is not
increased at the time of molding and solidification of the molding in injection molding. And
physical properties that ensure the flowability of the molded product are required.
[0020]
FIG. 2 shows the gate position of an example edge with injection molded elastomer.
FIG. 2 is a partial cutaway view of the edge secured around the circumference of the cone 1 and
shows the position corresponding to the edge in a mold for forming the edge.
[0021]
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First, using a soft segment having a small, uniform rubber particle size and having a
processability even if the amount of an olefin resin which is a hard segment is reduced, a
polyolefin elastomer which can be processed is used as a material for injection of the edge of the
thermoplastic elastomer. It shall be filled in the injector.
[0022]
In FIG. 2, the position of the gate 11 for injecting the material at the time of injection molding is
the position of the mold in the circumferential direction of the edge.
Thereby, the material can be injected toward the circumferential direction of the edge. Here, the
number of gates 11 is one to three. Further, as indicated by 13, the thickness of the edge is in the
case of thin-walled forming of 0.2 to 0.35 mm.
[0023]
By injecting the material from the gate 11 in the circumferential direction of the edge into the
mold, the edge provided on the outer periphery of the cone serving as the speaker diaphragm is
formed. At this time, in FIG. 2, since the material flows in from the gate 11 provided in the
circumferential direction of the outer peripheral portion at the edge in the outer peripheral
direction, the flow direction and the orientation direction of the material are not directed in the
radial direction which is the vibration direction. Therefore, since the flow distribution of the
physical properties of the material is uniform, the orientation of the material does not become
uniform. Therefore, the physical properties of the material can be shaped so as not to cause
anisotropy.
[0024]
FIG. 3 is a view showing the shape of an example of an edge formed of an injection molded
elastomer, FIG. 3A is a plan view, and FIG. 3B is a side view. In FIG. 3A, when the flow-shaped
distributions of the physical properties of the material are uniform, as shown by 22, the shape of
the edge becomes equal in elongation rate in the radial vibration direction and the non-vibration
direction in the circumferential direction. Further, as indicated by 21, it is possible not to provide
an unnecessary discarding portion after molding on the outer peripheral portion of the edge.
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[0025]
As shown in FIG. 2, the mold for injection molding of the edge has a material 0.2 to a thickness of
0.2, after the material injected from the gate 11 in the circumferential direction of the edge is
pressure-equalized in a ring shape. It flows into an edge shape having a roll shape of 0.35 mm.
Here, as shown in FIG. 3, unnecessary waste portions after molding and bite portions for
narrowing down are not provided on the outer peripheral portion of the edge.
[0026]
Because of this limitation, the edge shape is ring-shaped and thin-walled, so the material is
packed in the radial vibration direction at the time of injection, and at the same time the material
flow direction is always circumferential along the entire roll shape. .
[0027]
Below, evaluation of F0 (resonance frequency) with respect to the hardness of edge material is
shown.
The following evaluation performed injection molding of the edge using the metal mold | die
mentioned above, bonded the diaphragm fitted to the shape | molded edge with an adhesive
agent, F0 was measured, and it was set as the judgment standard of softness.
[0028]
Here, in the measurement of F0, a speaker unit with a low minimum resonance frequency is
placed in a closed box with a hole closed at the edge periphery, the diaphragm attached with the
edge is stopped, and a sweep signal is added to the speaker from the low frequency The edged
diaphragm was vibrated to measure the resonant frequency.
[0029]
In addition, the elongation percentage of the thin molding edge in the flow direction (MD
(machine direction)) indicating the radial direction and the non-flow direction (TD (... (* Fill in))
indicating the circumferential direction) For measurement, for example, a molded article was
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prepared using a 100 mm square mold having a thickness of 0.3 mm, and the measurement was
performed.
[0030]
The observation of the material was performed as follows.
First, a thin piece was cut out of the molded article with a microtome for observation with an
electron microscope, and the thin piece was stained, and the shape and dispersion state of the
rubber were observed with a transmission electron microscope.
[0031]
Specific examples and comparative examples are shown below.
The materials used were all published values, and materials with hardness of JIS A 50 degrees
were compared. Implemented as a so-called dynamically cross-linked thermoplastic olefin-based
elastomer having the above-described soft segment having a uniform, small, uniform particle
diameter of rubber particles and having processability even if the amount of olefin resin as the
hard segment is small Exelink 1500 B of an example (manufactured by JSR), milastomer 5030 B
of dynamic crosslink type (manufactured by Mitsui Chemicals) as a comparative example, and
leostomer L-1050N of styrene-based elastomer (manufactured by Riken Technos) were used.
[0032]
The molding conditions were adjusted so that the same pack state could be obtained by making
the temperature 240 ° C., the injection speed, and the pressure holding conditions almost equal,
so that all types did not change. The thickness is 0.3 mm uniformly as shown in the figure. The
molded edges were glued to the same weight matched diaphragm and F0 was measured. The F0
value changed immediately after molding due to resin shrinkage, and the measured value was
unchanged from 48H after molding.
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[0033]
Table 1 shows F0 of the edge formed using each material. In addition, it was set as n (number) of
the measured edge = 5. In Table 1, as described above, a so-called dynamic cross-linking type of
heat having a soft segment having a small and uniformly dispersed rubber particle diameter and
having processability even if the amount of an olefin resin which is a hard segment is small In the
Exelink 1500B (manufactured by JSR) in the example as the plasticizable olefin elastomer, F0
was the lowest value of 49 (Hz).
[0034]
In addition, in the dynamically cross-linked type Mirastomer 5030B (manufactured by Mitsui
Chemicals) as a comparative example, F0 is 61 (Hz), and in the styrenic elastomer, leostomer L1050N (manufactured by Riken Technos), F0 is relatively 61 (Hz) It became a high value.
[0035]
[0036]
Further, in Table 1, the published hardness was 50 ° for all the materials.
Therefore, since F0 with respect to the hardness is the lowest in the Example 1050B in the
embodiment, it can be seen that there is elongation in the radial direction which is the vibration
direction and it is soft.
[0037]
In addition, to measure the elongation in the flow direction (MD) indicating the radial direction of
the edges of these materials and the non-flow direction (TD) indicating the circumferential
direction, cut out a sample from a material of 0.3 mm thickness and 100 mm square The
measurement of
[0038]
Table 2 shows the measurement results of the elongation in the flow direction (MD) indicating
the radial direction of the edge formed using each material and the non-flow direction (TD)
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indicating the circumferential direction.
[0039]
[0040]
In Table 2, as described above, a so-called dynamic cross-linking type of heat having a soft
segment having a small and uniformly dispersed rubber particle diameter and having
processability even if the amount of an olefin resin which is a hard segment is small In the
example of Exelink 1500B (made by JSR) as a plasticizable olefin elastomer, the elongation in the
flow direction (MD) showing the radial direction of the edge is 680 (%), and the elongation in the
non-flow direction (TD) shows the circumferential direction. The rate was the highest with 700
(%).
[0041]
In addition, in a dynamic cross-linked type Mirastmer 5030B (manufactured by Mitsui
Chemicals) as a comparative example, the elongation in the flow direction (MD) indicating the
radial direction of the edge is 390 (%) and the non-flow direction (TD indicates the
circumferential direction) In the case of styrenic elastomer, Leostomer L-1050N (manufactured
by Riken Technos), the elongation rate of the flow direction (MD) indicating the radial direction
of the edge is 400 (%), and the circumferential direction is not The elongation in the flow
direction (TD) was relatively low at 620 (%).
[0042]
As described above, in each material, the elongation of the edge is different between the flow
direction (MD) indicating the radial direction and the non-flow direction (TD) indicating the
circumferential direction. Is a value showing a large elongation without change to almost, but the
other two comparative examples had a clear difference in directionality.
That is, in both of the two comparative examples, the elongation in the non-flow direction (TD) in
the circumferential direction is a value significantly higher than the elongation in the flow
direction (MD) in the radial direction of the edge.
[0043]
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From these facts, it can be seen that in thin-wall injection molding of an elastomer, the influence
of shear force is large, and the directionality of elongation is largely different even with the same
hardness.
Next, a thin piece with a cross section of 0.3 mm in thickness formed at the edge using Exerink
1500B (made by JSR) of the example was cut out with a freezing microtome, and this thin piece
was stained and observed with a transmission microscope.
[0044]
It was found that the cut surface had a morphology of a sea-island structure, and was directed in
the flow direction of the material resin.
The directionality showing an anisotropic orientation is small, and the one with a small F0 of the
edge is uniform with the size of the island part being a rubber component being 5 μm or less,
and the amount of hard segment being a sea part being It turned out that there are very few.
In this case, the molded edge cross-section is uniformly dispersed with a rubber particle diameter
of 5 μm or less in transmission electron microscopic photography, and the area is 95% or more
in 0.1 mm square.
[0045]
On the other hand, as a comparative example, Mirastomer 5030B (made by Mitsui Chemicals) of
the dynamic crosslinking type has an uneven separation structure and uneven particle diameter,
and also has a large amount of hard segments.
The styrenic elastomer Leostomer L-1050N (manufactured by Riken Technos) has large rubber
domains of 10 μm or more and small domains of several μ, and is combined with the hard
segment to form a three-component system. There are many segment portions, and the resin is
directed in the flow direction showing anisotropic orientation.
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[0046]
From the embodiment described above, in order for the edge formed by the injection-molded
elastomer to exert its effect, the rubber particle diameter is uniformly dispersed by taking into
consideration the constitution of the material because it is a thin-walled molding. Therefore, it is
possible to change the concept of conventional elastomer edges.
These are applied in the case of thin-wall molding by pressure, and in the case of thin-wall
molding by pressure, the same applies to sheet molding using a thermoplastic elastomer, vacuum
molding, compressed air molding and mold molding. That applies.
[0047]
Needless to say, the present invention is not limited to the above-described embodiment, and
may be modified as appropriate without departing from the scope of the present invention
described in the claims.
[0048]
It is explanatory drawing of a speaker vibration part.
FIG. 6 illustrates the gate position of an example edge with an injection molded elastomer. FIG.
3A is a plan view and FIG. 3B is a side view, illustrating the shape of an example of an edge
formed by an injection molded elastomer.
Explanation of sign
[0049]
11: gate, 12: number of gates (1 to 3 points), 13: edge thickness (0.2 to 0.35 mm), 14: low
hardness of hardness A20 to general purpose of hardness A70, 21: edge peripheral portion
There is no cut-off portion in 22, 22 ... the radial and circumferential elongations are equal
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