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JPH0522792

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DESCRIPTION JPH0522792
[0001]
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a
speaker and a support for a speaker diaphragm excellent in acoustic characteristics.
[0002]
2. Description of the Related Art The support of a speaker diaphragm such as a speaker cone
edge or a damper is to maintain the correct posture of the diaphragm or the voice coil driven by
the voice coil and to not adversely affect the vibration, itself Is required to cause no abnormal
vibration such as resonance and to sufficiently damp the propagation of the vibration.
Furthermore, air tightness is also required so that air vibrations of different phases mix on the
front and back of the diaphragm and do not interfere.
[0003]
Conventionally, in order to solve such problems, in terms of raw materials, from paper
impregnated with resin to resin, cotton cloth etc. coated with an elastomer, a laminate obtained
by further laminating polyurethane foam, polyurethane, polystyrene-polyolefin copolymer
elastomer Various improvement proposals have been made, such as foams and polyurethane
films made of a mixture of ethylene / vinyl acetate copolymer and polyethylene. Moreover, the
device has been devised such as forming the shape into a concentric wave-shaped cross section.
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1
[0004]
SUMMARY OF THE INVENTION In the case of conventional cotton cloth or the like coated with
polyurethane foam, the rigidity, the fabric weight and the thickness become large, which
adversely affects the diaphragm. Furthermore, there is a problem that the process becomes
complicated when forming a concentrically corrugated cross-section.
[0005]
In addition, although the support of the diaphragm made of foam has relatively good formability,
in the case of an open cell structure, the air on the back side of the diaphragm leaks to the
surface side through the open cells and the sound quality is good In the case of the closed cell
structure, the rigidity is increased and the internal loss is reduced. In addition, it is necessary to
reduce the strength because the foam structure is low, and to increase the strength, it is
necessary to lower the porosity or to increase the fabric weight and bending rigidity in any case.
Absent. In addition, polyurethane foams have deteriorated with time, and can not withstand longterm use. On the other hand, although the polyurethane film has a relatively small deterioration,
it is likely to cause abnormal vibration with respect to a large output, and there is a problem that
a sufficient sound quality can not be obtained.
[0006]
An object of the present invention is to provide a support for a diaphragm of a speaker which is
excellent in formability, has low flexural rigidity and small area weight, has a large internal loss,
is excellent in acoustic characteristics, and is also excellent in durability.
[0007]
SUMMARY OF THE INVENTION According to the present invention, a self-bonding nonwoven
fabric consisting of polyurethane elastic fibers having an average fiber diameter of 7 to 30 μm
and a polyurethane film are integrally laminated, and the 30% modulus is 0.8 to 4 g / cm. It is a
support of a speaker diaphragm characterized in that the bending resistance is 100 mm or less.
[0008]
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2
First, as an important point in the present invention, it may be necessary that the average fiber
diameter of the polyurethane elastic fiber constituting the non-woven fabric be 7 to 30 μ,
preferably 10 to 25 μ.
As the average fiber diameter increases, the surface area of the fibers decreases, so that
deterioration with time due to oxidation, hydrolysis, light or the like decreases, and the durability
becomes excellent.
However, as the average fiber diameter increases, the bending stiffness of the fibers increases,
and the number of constituent fibers per unit area of the non-woven fabric decreases. Therefore,
the bending rigidity and the tensile rigidity of the non-woven fabric become large, and the
bending rigidity when laminated with the polyurethane film becomes large. Furthermore, the
internal loss is also reduced because the cross-bonding points between the fibers are reduced,
and the acoustic characteristics are inferior when incorporated in the speaker. On the other hand,
the smaller the average fiber diameter, the smaller the flexural rigidity of the fiber and the
flexibility, but the larger the surface area of the fiber, the greater the deterioration of the fiber
due to oxidation or light and the like, resulting in poor durability. Thus, in order to balance
acoustic characteristics and durability, in the present invention, a polyurethane elastic fiber nonwoven fabric having an average fiber diameter of 7 to 30 μm is used.
[0009]
The self-bonding non-woven fabric made of polyurethane elastic fibers having an average fiber
diameter of 7 to 30 μ is, for example, a high-temperature, high-speed gas flow jetted from the
adjacent gas jet holes or jet grooves simultaneously with discharging the thermoplastic
polyurethane resin from the melt extrusion spinneret. Thus, it can be produced by the so-called
meltblown method of collecting in the form of a non-woven fabric on a moving mesh conveyor
belt conveyor-like collector while making it a very fine fiber stream and still sticky. By changing
the discharge amount of the polyurethane resin from the spinneret, the temperature and the flow
velocity of the jetted gas, and the like, it is possible to manufacture a non-woven fabric having
different average fiber diameter and formation. It is preferable that the non-woven fabric is an
isotropic one in which constituent fibers are not arranged in one direction, but are uniformly
deposited all over without directionality. In addition, it is preferable that the non-woven fabric is
a uniform non-woven fabric that does not contain polymer balls produced by so-called poor
thinning such as shot.
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[0010]
The basis weight of the nonwoven fabric of the present invention varies depending on the size of
the speaker to be used, the allowable input and the like, but is in the range of 50 to 300 g / m 2,
preferably 70 to 200 g / m 2. As the fabric weight increases, the tensile rigidity and the bending
rigidity increase and the inertial force also increases, which adversely affects the vibration of the
diaphragm and degrades the sound quality. On the contrary, if the fabric weight is too small, the
tensile rigidity becomes too small, and the posture of the diaphragm can not be maintained
properly or the vibration damping effect becomes small, so that sufficient effect can not be
obtained, and uniform formation It becomes difficult to produce nonwoven fabric efficiently.
[0011]
The thermoplastic polyurethane used for the polyurethane elastic fiber non-woven fabric of the
present invention has an average molecular weight of 500 such as polyester diol obtained by
condensation polymerization of low molecular weight diol and dicarboxylic acid, polylactone diol
obtained by ring-opening polymerization of lactam, polyoxyalkylene glycol, etc. It is a
thermoplastic polyurethane obtained by reacting ~3,000 polymer glycols, an organic
diisocyanate, and a low molecular weight compound having two active hydrogen atoms.
[0012]
The general thermoplastic polyurethanes described above are used for the purpose of the
present invention, but when used under particularly severe conditions such as car stereos, the
following more durable polyurethanes are used Is preferred.
Preferred thermoplastic polyurethanes from the viewpoint of balance between flexibility and
durability are aliphatic diols or alicyclic diols having 4 or more carbon atoms, preferably 6 to 12
carbon atoms, and more preferably 8 to 12 carbon atoms, for example, 3 -Methyl-1,5pentanediol, hexanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1,11-undecanediol,
1,12-dodecanediol, 2- Or linear or side chain such as 3-methyl-1,7-heptanediol, 2- or 3-methyl1,8-octanediol, ω, ω'-dihydroxy-1,4-dimethylcyclohexane, etc. Aliphatic diol or at least one diol
selected from alicyclic diol, and aliphatic dicarboxylic acid such as succinic acid, glutaric acid,
adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, dodeca Polyester diol having an
average molecular weight of 600 to 3,000 obtained by reaction with at least one dicarboxylic
acid selected from dicarboxylic acids or esters of such dicarboxylic acids, and as organic
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diisocyanates, for example, phenylene diisocyanate, tri Organic diisocyanates mainly composed
of aromatic or alicyclic diisocyanates such as di-isocyanate, 4,4'-diphenylmethane diisocyanate,
4,4'-dicyclohexylmethane diisocyanate, cyclohexane diisocyanate, isophorone diisocyanate,
xylylene diisocyanate, if necessary Organic diisocyanate selected from aliphatic diisocyanates or
diisocyanates having a naphthalene ring, and low molecular compounds having two active
hydrogen atoms For example, a chain extender selected from diols, amino alcohols, hydrazines,
diamines and the like. Then, the polymer diol, the organic diisocyanate and the chain extender
are selected at a desired composition ratio, and they are polymerized by a melt polymerization
method, a bulk polymerization method, a solution polymerization method or the like to obtain a
thermoplastic polyurethane. In order to obtain a non-woven fabric with good uniformity, this
thermoplastic polyurethane has a content of 45 to 75% by weight of the polymer diol which
becomes a soft segment in the composition at the time of polyurethane production.
[0013]
Polycarbonate-based polyurethanes have high durability such as hydrolysis resistance and
oxidation degradation resistance, but generally have poor flexibility and it is difficult to obtain
those satisfying the performance of the present invention. However, polycarbonate-based
polyurethanes having as a soft segment a polycarbonate-based diol containing a diol unit derived
from an aliphatic diol having 8 to 12 carbon atoms and a carbonyl unit are relatively flexible and
can be used in the present invention.
[0014]
Prior to melting the polyurethane, or prior to spinning, carbon black may be added to the
thermoplastic polyurethane as a coloring agent to improve the photodegradation. The amount of
carbon black added to improve the photodegradability of the polyurethane elastic fiber is in the
range of 0.05 to 1.5% by weight based on the polyurethane resin. When the addition amount is
small, sufficient effects can not be obtained, and when the addition amount is large, the
polyurethane elastic fiber becomes hard and the acoustic characteristics deteriorate.
[0015]
In addition, a hindered phenol compound and / or a benzotriazole compound may be added to
the thermoplastic polyurethane prior to melting the polyurethane or prior to spinning. The
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addition amount is in the range of 0.1 to 3% by weight with respect to the thermoplastic
polyurethane. The action of these additives is to actively react and stabilize the active group
possessed by the additive in the dissociated portion in order to prevent the thermally melted
polyurethane from dissociating and causing an undesirable side reaction. Together with the
effect of suppressing the oxidation or photodegradation of the additive. Therefore, if the additive
amount is small, the dissociated portion of the polyurethane is sufficiently blocked and can not
be stabilized. In addition, if the amount added is large, the additive may cause an undesirable side
reaction to the polyurethane, which deteriorates the performance of the polyurethane.
[0016]
In addition, in order to improve the spinnability and spinnability of polyurethane and to form a
stable fiber stream, silicone oil or polyolefin resin such as polyethylene or polypropylene may be
added to polyurethane at any stage before spinning. . As an applicable silicone oil, it is a
compound which is inactive to molten polyurethane and does not increase the vapor pressure of
the polyurethane melting system, and a silicone oil having a viscosity in the range of 2 to 150
poise at 30 ° C., for example An oil selected from compounds such as dimethylpolysiloxane and
methylphenylpolysiloxane and other heat resistant common silicone oils can be added in an
amount of 0.05 to 2% by weight based on polyurethane. When a non-elastic resin such as a
polyolefin resin is mixed, the modulus of the obtained non-woven fabric tends to be high, and the
addition amount is preferably 10% by weight or less.
[0017]
By mixing the stabilizer, silicone oil and the like in this way, the meltblown moldability of the
polyurethane is improved, and a uniform non-woven fabric having a stable fiber diameter can be
stably produced, and the acoustic characteristics are further improved. It becomes.
[0018]
The self-bonding nonwoven fabric of polyurethane elastic fibers obtained in this manner is
laminated with a polyurethane film to form a support of the speaker vibrator of the present
invention.
That is, since the polyurethane non-woven fabric is composed of elastic fibers with a good degree
of fiber uniformity, the rigidity is small and the vibration damping effect is also high in the small
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deformation required to the cone edge of the speaker, but the non-woven fabric is air permeable.
For this reason, when used alone, there arises a problem that the oscillations of opposite phases
on the front and back of the diaphragm interfere with each other. In addition, abrasion and
abrasion may result in fuzzing, which impairs the appearance of the product's beauty, whereas
polyurethane films are impervious, and fuzzing due to abrasion and abrasion is the use of this
application. Then it is good enough not to be a problem at all.
[0019]
As the polyurethane used for the polyurethane film, the same thermoplastic polyurethane
described above as used for the non-woven fabric can be used. In this case, the same
polyurethane as the non-woven fabric may be used, or polyurethane of another composition may
be used. The thickness of the polyurethane film is preferably in the range of 10 μ to 50 μ. Also
in this film, if the thickness is too thick, the rigidity and the inertia force become large, which
adversely affects the vibration of the diaphragm. On the other hand, if the thickness is too thin,
the strength is reduced and it is easily broken. The rigidity, the moldability, etc. can be adjusted
by mixing an appropriate amount of another resin with the resin constituting the polyurethane
film.
[0020]
The lamination integration of the polyurethane elastic fiber non-woven fabric and the
polyurethane film can be performed by a method such as calendering with an emboss roll or a
flat roll, or bonding with ultrasonic waves. In this integration, it is necessary to carry out under
the condition that the non-woven fabric is not formed into a film. Alternatively, the polyurethane
elastic fibers can be directly laminated and integrated on the polyurethane film by melt-blowing.
[0021]
The sheet thus laminated and integrated has a 30% modulus (stress per unit width at 30%
elongation, an average widthwise average) of 0.8 to 4 g / cm / g / m 2, a bending resistance
(cantilever method, average widthwise average) ) Should be less than 100 mm. 30%If the
modulus is small, the ability to control the posture of the speaker cone and voice coil is
weakened, and the reproducibility of the sound is reduced. On the other hand, if the 30%
modulus is increased or the stiffness is increased, the response to the input signal to the speaker
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is deteriorated or abnormal vibration is easily generated at the time of large input and the like,
which both adversely affect the sound quality. In addition, it is preferable that the longitudinal
and transverse ratios of these 30% modulus and bending resistance are isotropic close to 1.
[0022]
The support of the speaker vibrator of the present invention thus obtained is flexible, has a large
internal loss, is excellent in acoustic characteristics, and is excellent in durability. The durability
can be evaluated, for example, by the retention of 30% modulus after dry heat treatment at 110
° C. The support of the present invention has a retention of 30% modulus of 50% or more,
preferably 80% or more, more preferably 90% or more, when dried by heat treatment at 110 °
C. for 1 week. 30%If the modulus retention is less than 50%, even the sound quality that is
initially good may deteriorate over time during use, making long-term use difficult. The
polyurethane elastic fiber of the present invention is small in deterioration due to oxidation and
hydrolysis from the surface because the average fiber diameter is 7 μ or more, but by selecting
the above-mentioned polyurethane resin with high resistance to deterioration, it is more durable
can do.
[0023]
Since the support of the speaker diaphragm of the present invention is made of thermoplastic
polyurethane, it can be processed into corrugations by press molding or the like like
conventional products and can be used for cone edges and dampers, as well as flat without
corrugation processing But you can use it.
[0024]
EXAMPLES The present invention will next be described by way of specific examples, which
should not be construed as limiting the invention thereto.
In the examples, parts and percentages are by weight unless otherwise specified.
[0025]
EXAMPLE 3 A nitrogen in a polymer consisting of a polyester diol of average molecular weight
1,500 consisting of 1-methyl-1,5-pentanediol and adipic acid, 1,4-butanediol and molecular
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weight less than 500 and 4,4'-diphenylmethane diisocyanate A polyurethane having a content of
3.8% was obtained.
[0026]
In the meltblowing apparatus described in JP-A-49-48921, etc., spinning holes with a diameter of
0.3 mm are arranged in a line at a pitch of 1 mm, and 1.2 mm thick slit-like gas discharge holes
are used on both sides thereof. Blend the above polyurethane and the above polyurethane with
an original wearing masterbatch containing carbon black to discharge this as a polyurethane
containing 0.5% carbon black at a melting temperature of 225 ° C. at 0.30 g / m 2 per spinning
hole, 225 ° C. The heated air was jetted from the slit-like gas discharge hole at a pressure of 0.5
kg / cm 2 to carry out melt blowing.
At this time, the jetted fiber stream was collected on a belt conveyor-like collector of wire mesh
traveling at a position of 20 cm below the spinning holes to obtain a self-bonding meltblown nonwoven fabric having a fabric weight of 205 g / m 2 made of polyurethane fibers. The non-woven
fabric was observed by a scanning electron microscope in an enlarged manner and as a result,
the average fiber diameter was 24 μ.
[0027]
Also, film formation was carried out using the same polyurethane as a raw material using a T-die
type film forming machine to obtain a polyurethane film with a thickness of 30 μ. The
polyurethane non-woven fabric and the polyurethane film are layered and supplied to an
embossing device combining an embossing roll having a square convex shape and an area of
10% of the area on the roll surface and a flat roll having a flat surface, roll temperature 105 °.
C. Bonding was performed at a press wire pressure of 20 kg / cm and a processing speed of 20
m / min.
[0028]
The obtained non-woven film laminate has a basis weight of 244 g / m 2, a thickness of 0.94
mm, an apparent density of 0.26 g / cm 3, an average strength of 42.3 g / cm / g / m 2, and an
elongation (average height). The mechanical properties were 361%, bending resistance
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(cantilever): 66 mm, and 30% modulus: 0.6 g / cm / g / m 2. In addition, the 30% modulus
retention after one week of 110 ° C. dry heat treatment was 79%.
[0029]
Using this, hot press molding and cutting were carried out to prepare a support (cone edge) of
the diaphragm of the speaker of the wave-shaped cross section, and this was installed in an
actual speaker to investigate acoustic characteristics and the like. As a result, the cone edge of
the speaker not only maintains the correct attitude of the diaphragm, but also does not adversely
affect the vibration, and does not cause any abnormal vibration such as resonance, and
effectively damps the vibration. Met. In addition, it had adequate air tightness that air vibrations
of different phases do not mix and interfere on the front and back of the diaphragm.
Furthermore, the ability of the cone edge to follow the vibration was particularly good, and the
ability to smoothly return to the original shape even after large deformation was excellent. The
practical durability of these various performances was also good. A speaker using such a speaker
diaphragm support has the above-mentioned excellent acoustic performance and durability.
[0030]
EXAMPLE 23 A polyurethane is obtained under the same conditions as in Example 1 except that
a mixture of 2-methyl-1,8-octanediol and 1,9-nonanediol is used instead of 3-methyl-1,5pentanediol. Melt-blowing was carried out under the same conditions as in Example 1 to obtain a
self-bonding melt-blown non-woven fabric. The average diameter of fibers constituting the
meltblown non-woven fabric was 25 μ when measured by a scanning electron micrograph.
[0031]
The same polyurethane as this was used as a raw material for film forming using a T-die film
forming machine to obtain a polyurethane film with a thickness of 30 μ. This polyurethane film
and self-bonding meltblown non-woven fabric are laminated in layers, and the roll temperature is
105 with the embossing device combining an embossing roll with a square area of the convex
part shape and a 10% area ratio on the roll surface and a flat surface. The bonding process was
performed under the conditions of ° C., a press linear pressure of 20 kg / cm, and a processing
speed of 20 m / min. The obtained non-woven film laminate has a basis weight of 241 g / m 2, a
thickness of 0.93 mm, an apparent density of 0.25 g / cm 3, a strength (average horizontal) of
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43.1 g / cm / g / m 2 and an elongation (average horizontal). It had mechanical physical property
values of: 331%, bending resistance (cantilever): 64 mm, 30% modulus: 1.5 g / cm / gm 2. In
addition, the 30% modulus retention after one week of 110 ° C. dry heat treatment was 91%.
[0032]
Using this, hot press processing and cutting processing were performed to create a cone edge of
a speaker having a corrugated cross section, and the product was attached to the diaphragm of
an actual speaker to examine acoustic characteristics and the like. As a result, the cone edge of
the speaker not only maintains the correct attitude of the diaphragm, but also does not adversely
affect the vibration, and does not cause any abnormal vibration such as resonance, and
effectively damps the vibration. Met. In addition, it had adequate air tightness that air vibrations
of different phases do not mix and interfere on the front and back of the diaphragm.
Furthermore, the ability of the cone edge to follow the vibration was particularly good, and the
ability to smoothly return to the original shape even after large deformation was excellent. The
practical durability of these various performances was also good. A speaker using such a speaker
diaphragm support has the above-mentioned excellent acoustic performance and durability.
[0033]
Comparative Example 1 Using exactly the same polyurethane as in Example 1, and using the
same meltblowing apparatus, the thickness of the slit-like gas discharge holes was changed to 0.2
mm, and the polymer discharge amount per spinning hole was 0.2 g / min. The melt temperature
of the polymer is 250 ° C, the heating air temperature is 250 ° C, the pressure is 1.6 kg / cm2
gauge pressure, and the other conditions are the same. A fused meltblown nonwoven was
obtained. The average fiber diameter of the polyurethane fiber forming this non-woven fabric
was 6.1 μ, which was outside the scope of the present invention.
[0034]
The same 30 μ thick polyurethane film as that used in Example 1 was subjected to embossing
lamination processing by the same embossing apparatus as in Example 1 under the same
embossing conditions. The obtained nonwoven fabric / film laminate had a basis weight of 241 g
/ m 2, a thickness of 0.97 mm, an apparent density of 0.28 g / cm 3, a strength (average of the
sideways) of 41.1 g / cm / g / m 2, an elongation (the average of the horizontal sides). ): 311%,
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bending resistance (cantilever): 62 mm, 30% modulus: 1.3 g / cm / g / m 2 mechanical
properties. In addition, the 30% modulus retention after one week of 110 ° C. dry heat
treatment was 43%.
[0035]
The acoustic characteristics etc. as a cone edge of a speaker were investigated by the method
similar to Example 1 about this. As a result, the cone edge of the speaker not only maintains the
correct posture of the diaphragm, but also effectively damps the vibration without generating
abnormal vibration itself, and there is no problem in the acoustic performance. However, among
such initial good performance, the attitude retention property of the diaphragm and the shape
recovery property at the time of large deformation start to decrease after 6 to 9 months of actual
use period and become impractical after one year The
[0036]
Comparative Example 2 Using polyurethane having a nitrogen content of 4.3% obtained from the
same raw material as in Example 1 and using the same meltblowing apparatus, the polymer
discharge amount per spinning hole was 0.6 g / min, and the melting temperature of the polymer
was The temperature is changed to 220 ° C., the heating air temperature is 220 ° C., and the
pressure is changed to 0.2 kg / cm 2 gauge pressure, and the other conditions are the same, and
melt blowing is performed to obtain a self-bonding meltblown nonwoven fabric having a fabric
weight of 206 g / m 2. The The average fiber diameter of the polyurethane fiber forming this
non-woven fabric was 42μ, which is outside the present invention.
[0037]
The same 30 μ thick polyurethane film as that used in Example 1 was subjected to embossing
lamination processing by the same embossing apparatus as in Example 1 under the same
embossing conditions. The obtained nonwoven fabric / film laminate has a basis weight of 241 g
/ m 2, a thickness of 1.08 mm, an apparent density of 0.22 g / cm 3, a strength (average
horizontal) of 51.1 g / cm / g / m 2, an elongation (vertical average). ): 244%, bending resistance
(cantilever): 110 mm, 30% modulus: 4.4 g / cm / g / m 2 of mechanical physical properties. The
acoustic characteristics etc. as a cone edge of a speaker were investigated by the method similar
to Example 1 about this. As a result, the cone edge of the speaker has no problem in maintaining
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the correct attitude of the diaphragm, but the ability of the cone edge to follow the vibration is
poor, and abnormal vibration may occur around the diaphragm at large deformation. The
[0038]
According to the present invention, the support of the speaker diaphragm in which the
polyurethane fiber self-bonding nonwoven fabric and the polyurethane film are integrally
laminated is excellent in moldability, moderately low in bending rigidity, and large in internal
loss, It is very excellent in acoustic characteristics and the like. Its long-term practical durability
is also excellent. By using the support of the speaker diaphragm of the present invention as a
speaker, it is possible to obtain a speaker excellent in practical durability and acoustic
characteristics.
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