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JPH11285094

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DESCRIPTION JPH11285094
[0001]
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a
speaker diaphragm. More specifically, the present invention relates to a speaker diaphragm
having very excellent acoustic characteristics and excellent manufacturing efficiency.
[0002]
2. Description of the Related Art Conventionally, as a speaker diaphragm, a speaker diaphragm
obtained by impregnating a base material with a thermosetting resin, molding and curing is
known. As a base material, a plain weave woven fabric of rigid reinforcing fibers such as carbon
fiber (CF) and glass fiber (GF) or a non-woven fabric obtained by resin coating and randomly
bonding chopped fibers such as CF and GF is known. There is. An epoxy resin is known as a
thermosetting resin (matrix resin) to be impregnated. Although CF and GF used for a base
material have large elastic modulus, they are rigid and extremely small in internal loss. The epoxy
resin to be the matrix resin has a small toughness and a small internal loss. As a result, according
to the speaker diaphragm obtained by combining such a base material and a matrix resin, a large
and sharp resonance occurs. As such, this type of speaker diaphragm is not sufficient for use as a
full range speaker. In addition, when using a woven fabric as the base material, it is easy to cause
changes in physical properties due to the directionality (longitudinal and longitudinal anisotropy)
of the woven fabric, and the occurrence of misalignment at the time of molding causes uneven
properties. There's a problem.
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1
[0003]
On the other hand, although a speaker diaphragm formed by fusing thermoplastic resin fibers by
heat press has been proposed, it is difficult to obtain high physical properties (for example,
Young's modulus) because thermoplastic resin has a low elastic modulus. There are problems
such as the presence of heat resistance and insufficient heat resistance. In order to solve the
above-mentioned problems, in recent years, a non-woven fabric made of high elastic modulus
organic fibers bound with a matrix resin or a binder has been developed, and attempts to
improve characteristics such as internal loss are active. It has become to. Here, a chemical bond
method and a needle punch method are known as a method of forming such a high elastic
modulus organic fiber in a non-woven fabric. Furthermore, if necessary, a filler is added to the
matrix resin or the binder.
[0004]
However, according to the technology using the non-woven fabric made of the above-mentioned
high elastic modulus organic fiber, there is a problem that the strength of the non-woven fabric is
low and it is difficult to handle or non-uniform properties occur. . Furthermore, when forming a
non-woven fabric, the chemical bonding method has a problem that the acoustic characteristics
are insufficient because wrinkles and cracks easily occur, and in the needle punch method, there
is a problem that physical properties are easily changed due to directivity. is there. Furthermore,
in the combination of the conventional matrix resin and the filler, there is a problem that
sufficient internal loss can not be obtained and the density is large. Moreover, it is well known
that the workability of the matrix resin used for these diaphragms is poor.
[0005]
The present invention has been made to solve the above-described conventional problems, and
an object thereof is to provide a speaker diaphragm having excellent acoustic characteristics and
excellent manufacturing efficiency. .
[0006]
[Means for Solving the Problems] As a result of intensive studies on the fibers forming the nonwoven fabric, the inventors of the present invention have excellent acoustic characteristics by
using the non-woven fabric molded using protein fiber, and the production efficiency As a result,
the present invention has been completed.
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[0007]
The speaker diaphragm of the present invention is obtained by impregnating a non-woven fabric
with a thermosetting resin composition, and molding and curing the non-woven fabric, wherein
the non-woven fabric is formed of a fiber material containing protein fibers. And unsaturated
polyester resin as a main ingredient.
Another speaker diaphragm of the present invention has a plurality of non-woven fabric layers,
and the plurality of non-woven fabric layers are impregnated with a thermosetting resin
composition, molded and cured, and at least one of the plurality of non-woven fabric layers. One
is made of a non-woven fabric formed from a fiber material containing protein fiber, and the
thermosetting resin composition contains unsaturated polyester resin as a main ingredient.
In a preferred embodiment, the protein fiber is a silk thread consisting of a natural silk fiber from
which sericin has been substantially removed from the outer surface. In a preferred embodiment,
the sericin content of the silk yarn is 1% by weight or less. In a preferred embodiment, the
density of the silk yarn is 0.8 to 1.2 denier. In a preferred embodiment, the plurality of nonwoven fabric layers include a non-woven fabric layer formed of the silk yarn and a non-woven
fabric layer formed of high elastic modulus organic fibers. In a preferred embodiment, the high
modulus organic fiber is a meta-aramid fiber. In a preferred embodiment, the speaker diaphragm
of the present invention alternately has a non-woven fabric layer formed of the silk thread and a
non-woven fabric formed of the high elastic modulus organic fiber. In a preferred embodiment,
the non-woven fabric is mesh-like. In a preferred embodiment, the thermosetting resin
composition contains a rod-like mineral. In a preferred embodiment, the rod-like mineral is
graphite. In a preferred embodiment, the graphite has an average particle size in the range of 4
to 10 μm. In a preferred embodiment, the rod-like mineral is contained in a range of 20 to 50
parts by weight with respect to 100 parts by weight of the unsaturated polyester resin. In a
preferred embodiment, the thermosetting resin composition further contains a microballoon. In a
preferred embodiment, the microballoons are selected from organic microballoons based on
vinylidene chloride-acrylonitrile copolymer or inorganic microballoons based on borosilicate
glass. In a preferred embodiment, the microballoons are contained in a range of 5 to 20 parts by
weight with respect to 100 parts by weight of the unsaturated polyester resin.
[0008]
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BEST MODE FOR CARRYING OUT THE INVENTION The speaker diaphragm of the present
invention is formed by impregnating a non-woven fabric with a thermosetting resin composition,
and molding and curing it. The non-woven fabric is formed of a fiber material containing protein
fibers. That is, the non-woven fabric may be formed only of protein fibers, or may be formed of a
fiber material containing protein fibers and other fibers. As protein fibers, typically, natural silk
yarn and wool can be mentioned. Natural silk yarn is particularly preferred. More preferably, the
silk yarn consists of natural silk fibers substantially free of sericin from the outer surface thereof.
Here, "substantially removed" means that the sericin content of the silk yarn is 1% by weight or
less (note that sericin is 20% in silkworm form, 17-18% silk by silk yarn) Are generally known to
be contained in Sericin is removed from the silk by any suitable method (eg, boiling with mildly
alkaline water). By using a silk thread from which sericin has been removed, a speaker
diaphragm having extremely excellent acoustic characteristics can be obtained. Preferably, the
fiber density of silk yarn is 0.8 to 1.2 denier (fiber diameter is 9.5 to 11.7 μm). A silk thread
having a thickness in this range is excellent in flexibility, moldability and operability, has a high
elastic modulus, and can be well impregnated with an unsaturated polyester resin. In addition, as
said other fiber, arbitrary appropriate fibers (for example, carbon fiber, glass fiber) are used.
[0009]
The non-woven is formed from the above fibrous material using any suitable method. As a
representative example of the method of forming the non-woven fabric, a fluid entanglement
method using a liquid such as water or a gas such as air, or a method of mechanically
intertwining a fiber material can be mentioned. Fluid entanglement is preferred in that a nonwoven fabric having a small anisotropy of elastic modulus and good formability can be obtained.
For example, a nonwoven fabric can be obtained by randomly orienting the above-mentioned
fiber material by an air flow by a dry method to form an accumulation layer, and then
entangleing the fibers of the accumulation layer by a hydro-entanglement method. The basis
weight of the non-woven fabric used in the present invention may vary depending on the
purpose, but is typically 30 to 150 g / m 2. Many products are marketed as a nonwoven fabric
obtained by water-flow legalization etc.
[0010]
In another embodiment, the speaker diaphragm of the present invention has a plurality of nonwoven layers, and the plurality of non-woven layers are also impregnated and cured with a
thermosetting resin composition. The number of layers of the non-woven fabric can be
appropriately set depending on the purpose, but is typically 3 to 6 layers. At least one of the
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plurality of non-woven fabric layers is made of non-woven fabric formed of a fiber material
containing the above-mentioned protein fiber. In other words, it may be a non-woven fabric in
which all of the plurality of non-woven fabric layers are formed from the above-mentioned fiber
material, and a part of the plurality of non-woven fabric layers may be such non-woven fabric.
Preferably, the plurality of non-woven fabric layers is referred to as a non-woven fabric layer
formed of the above-mentioned silk yarn (hereinafter referred to as "silk non-woven fabric
layer"). ) And a high elastic modulus organic fiber (hereinafter referred to as "organic nonwoven
layer"). And is stacked. Preferably, the silk non-woven fabric layer and the organic non-woven
fabric layer are alternately laminated. When laminating nonwoven fabrics, it is preferable to
laminate by shifting the orientation direction of the nonwoven fabrics by an appropriate angle
(for example, 30 °) as viewed from the normal direction of the nonwoven fabrics (the
directionality (anisotropy also in the nonwoven fabrics) Note that) is not completely eliminated).
The shift angle may be appropriately set according to the type of nonwoven fabric and the like.
By laminating the non-woven fabrics in the same direction, the orientations of the fibers of the
non-woven fabrics can be canceled each other, and as a result, deformation during molding can
be prevented.
[0011]
Preferably, the non-woven fabric (whether silk or high modulus organic fiber) is in the form of a
mesh. The mesh size (e.g., the roughness of the mesh, the shape of the pores of the mesh) may be
appropriately changed depending on the purpose, but for example, a mesh-like non-woven fabric
may be created using # 16 mesh. As said high elasticity modulus organic fiber, a meta-type
aramid fiber, a para-type aramid fiber etc. are mentioned. Representative examples of metaaramid fibers include polymetaphenylene isophthalamide. Representative examples of paraaramid fibers include aromatic polyamide fibers such as coparaphenylene-3,4'-oxydiphenylene
terephthalamide, PPTA (polyparaphenylene terephthalamide), and PET (polyethylene
terephthalate) fibers. Meta-aramid fibers are preferred in that silk and fiber elasticity are similar.
The thermosetting resin composition impregnated into the non-woven fabric contains an
unsaturated polyester resin as a main ingredient. In the present invention, any suitable
unsaturated polyester resin may be used depending on the purpose. Preferably, the
thermosetting resin composition contains a scaly mineral as a filler. Graphite, mica, talc are
mentioned as a representative example of the rod-like mineral. Graphite is preferable in that it
has conductivity and lubricity and is excellent in dispersibility as a filler. Preferably, the average
particle size of the rod-like mineral (in the present invention, the length of the longest part of the
rod is 4 to 10 μm). If the average particle size is less than 4 μm, the effect as a filler is often
insufficient. If the average particle size is more than 10 μm, the filler can not penetrate between
the non-woven fibers during the impregnation, so that effective reinforcement is often not
possible. The rod-like mineral is contained in the range of 20 to 50 parts by weight with respect
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to 100 parts by weight of the unsaturated polyester resin. If the content is less than 20 parts by
weight, the Young's modulus is often insufficient. If the content exceeds 50 parts by weight, it is
difficult for the moss-like mineral to enter between the fibers of the non-woven fabric, and as a
result, the moss-like mineral deposits on the surface of the non-woven fabric and peels off.
Absent. Preferably, the thermosetting resin composition further contains a microballoon. Here,
the microballoon is a generic term for hollow spheres. The microballoons include inorganic
microballoons and organic microballoons. The inorganic microballoons are typically made of
borosilicate glass as a main component. The organic microballoons are typically based on
vinylidene chloride-acrylonitrile copolymer.
The true specific gravity of such an inorganic microballoon is about 0.3 g / cm 3, and the true
specific gravity of an organic microballoon is about 0.02 g / cm 3, both of which are suitable as a
filler for a speaker diaphragm. The particle size of the microballoon is typically 40 to 60 μm.
The microballoons are contained in the range of 5 to 20 parts by weight with respect to 100
parts by weight of the unsaturated polyester resin. If the content is less than 5 parts by weight,
internal loss is often insufficient. When the content exceeds 20 parts by weight, the Young's
modulus is often insufficient.
[0012]
Furthermore, the said thermosetting resin composition contains various additives as needed.
Representative examples of such additives include curing agents, shrinkage reducing agents,
pigments and reinforcing materials. As a hardening agent, hardening agents (polymerization
initiator), such as an organic peroxide, and crosslinking agents, such as a vinyl monomer, are
mentioned, for example. The low shrinkage agent includes, for example, thermoplastic resins and
their solutions. As the pigment, a pigment of any appropriate color type may be used depending
on the purpose, but a black pigment is often used in the speaker diaphragm.
[0013]
Examples of the reinforcing material include mica, carbon fibers and whiskers. The particle size
of the mica may vary depending on the purpose (e.g. thickness of the resulting diaphragm). For
example, when the thickness of the target diaphragm is 0.3 mm, it is appropriate that the average
particle diameter of mica is about 10 μm and the particle diameter distribution is about 5 to 25
μm. The larger the particle size of mica, the larger the elastic modulus, but if the particle size is
too large, the nonwoven fabric will not be uniformly impregnated during molding due to steric
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hindrance. As a result, the rigidity at different portions of the diaphragm is greatly different,
which adversely affects the acoustic characteristics of the diaphragm. The addition amount of
mica may vary depending on the particle size of mica, etc., but in the case of mica having an
average particle size of 5 μm, it is 15 to 25 parts by weight with respect to 100 parts by weight
of unsaturated polyester resin. Is preferred. The reason is as follows. The elastic modulus
increases as the amount of mica added increases, and mica having an average particle diameter
of 5 μm can be uniformly dispersed up to 50 parts by weight with respect to 100 parts by
weight of the resin. However, if it is added too much, the weight of the diaphragm increases, and
mica will not be uniformly impregnated into the non-woven fabric at the time of molding due to
steric hindrance, and mica will gather in one place. As a result, the sound pressure is lowered in
the acoustic characteristics, and the energy is concentrated at a specific frequency to make the
balance worse. As the carbon fiber, polyacrylonitrile (PAN) based or pitch based carbon fiber is
used. As for the fiber length of carbon fiber, 40 micrometers or less are effective. When the fiber
length exceeds 40 μm, carbon fibers are not uniformly dispersed in a thin diaphragm, and it is
difficult to obtain sufficient physical properties (for example, smoothness). As the whiskers,
ceramic whiskers (eg, aluminum borate whiskers) are typically used. Preferably, the whiskers
have a length of 30 μm or less and a diameter of 1.0 μm or less. When the whiskers exceed this
size, the whiskers do not disperse uniformly in the thin diaphragm, and it is difficult to obtain
sufficient physical properties (for example, smoothness).
[0014]
The speaker diaphragm of the present invention is obtained by impregnating the non-woven
fabric or the laminate of the non-woven fabric (simply referred to as non-woven fabric in the
description of the manufacturing method) with the thermosetting resin composition and molding
and curing with a mold. Be Hereinafter, an example of the manufacturing method of the speaker
provided with the diaphragm of this invention is demonstrated. FIG. 1 is a schematic view for
explaining a molding process of a speaker provided with a diaphragm of the present invention.
First, the non-woven fabric 1 a is supplied from the raw material supply device 1. Typically, the
non-woven fabric 1a is prepared by being wound around the supply device 1 in a roll, and
delivered from the supply device 1 according to the flow of the process. Next, in order to prevent
deformation at the time of molding, both sides with respect to the feeding direction of the fed-out
nonwoven fabric 1 a are movably supported by the clamp 2. Next, a thermosetting resin
composition is supplied from the resin supply nozzle 3a to the non-woven fabric 1a, and a
thermosetting resin composition is supplied from the resin supply nozzle 3b to the lower mold
4b. The resin composition may be supplied to only one side of the non-woven fabric 1a, but
preferably, as shown in FIG. 1, the resin composition is supplied to both the upper side and the
lower side of the non-woven fabric 1a. This is because fillers and the like are prevented from
being unevenly distributed on one side of the diaphragm. Next, the non-woven fabric 1a supplied
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with the resin composition is hot-pressed to roll the resin composition and impregnate the entire
non-woven fabric 1a, thereby semi-curing the impregnated resin (primary molding). Thereafter,
die cutting and outer periphery cutting are performed, and the speaker diaphragm 5 is obtained.
[0015]
The heating temperature and the heating time (curing time) may be appropriately changed
depending on the type of the thermosetting resin, but typically, the heating temperature is 80 to
120 ° C., and the heating time is 1 to 3 minutes. The press pressure and the mold clearance may
also be changed as appropriate depending on the type or amount of thermosetting resin, the type
or density of non-woven fabric, or the thickness of the intended diaphragm. The typical pressing
pressure in the present invention is 10 to 40 kg / cm 2, and the mold clearance (corresponding
to the thickness of the obtained diaphragm) is 0.5 to 1.2 mm. On the other hand, the edge
material 11 a is supplied from the edge raw material supply device 11. The edge material 11a is
also rolled and prepared in the supply device 11, and is delivered from the supply device 11
according to the flow of the process. Next, the edge material 11 a is cut into an appropriate
length by the cutting blade 12. Thereafter, molding is performed by hot pressing with the lower
mold 13 b and the upper mold 13 a, and die cutting and inner / outer circumference cutting are
further performed to obtain an edge portion 14. The heating temperature, the heating time, the
press pressure and the mold clearance can be appropriately set according to the type of edge
material and the type of the target edge portion. Next, the speaker diaphragm 5 and the edge
portion 14 are set between the upper mold 6a and the lower mold 6b, and the thermosetting
resin is completely cured by the heat press, and the diaphragm and the edge are integrated.
Conversion takes place (secondary molding). The heating temperature, heating time, press
pressure and mold clearance may be set to any appropriate conditions. Finally, die cutting and
center hole cutting are performed to obtain the speaker 7.
[0016]
In the above embodiment, as a method of applying the resin composition, a method of rolling
with a mold has been described, but methods such as spray application and blade application
may also be applied. As described above, it is preferable to apply the resin composition on both
sides of the non-woven fabric (in particular, when the resin composition contains a scale-like
mineral (eg, graphite), the effect is remarkable). The reason is as follows. By applying the resin
composition to both sides of the non-woven fabric, a high strength graphite layer is formed on
both surfaces of the non-woven fabric at the time of molding. By sandwiching the non-woven
fabric with the graphite layer at the time of forming, the strength anisotropy present in the non-
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woven fabric is reduced after the forming. Furthermore, the presence of a strong graphite layer
on both sides improves both the internal loss and the Young's modulus. In the above
embodiment, although the case where the thermosetting resin of the diaphragm is cured in two
steps by primary molding and secondary molding has been described, if the edge portion is
prepared in advance, the diaphragm is cured. , Molding and integration with the edge can be
performed simultaneously. The loudspeaker diaphragm of the present invention can be used for
any loudspeaker (for example, loudspeakers for bass, mid tones, high tones). The shape of the
diaphragm may also be any suitable shape (e.g., cone, dome, flat).
[0017]
Hereinafter, the operation of the present invention will be described. According to the present
invention, by forming a non-woven fabric from a fiber material containing protein fibers, a
speaker diaphragm having very excellent acoustic characteristics can be obtained. This is
because protein fibers are excellent in vibration damping ability and can clearly separate the
fundamental sound, the overtones and the third overtones. Moreover, in the present invention, by
impregnating this non-woven fabric with the unsaturated polyester resin composition, the
speaker diaphragm can be manufactured with extremely excellent workability while maintaining
the excellent properties of the protein fiber. Unsaturated polyester resins have (i) a significantly
faster cure rate, (ii) lower viscosity and (iii) lower temperatures than impregnated resins (eg,
epoxy resins) used in conventional speaker diaphragms. This is because it has the advantages
that it can be molded, (iv) no pre-preg is needed, and (v) the addition of additives is easy. In
addition, since the protein fiber is degraded at a typical curing temperature (for example, 150 °
C.) of the conventional impregnated resin (epoxy resin), it is extremely difficult to use the
conventional impregnated resin and the protein fiber in combination Although low temperature
curable unsaturated polyester resins can be used in combination with protein fibers. As described
above, according to the present invention, by using a combination of protein fiber and
unsaturated polyester resin, a speaker diaphragm having very excellent acoustic characteristics
can be obtained with very high production efficiency. According to a preferred embodiment, a
silk thread made of natural silk fiber from which sericin has been substantially removed from the
outer surface is used as the protein fiber. By using such silk thread, the acoustic properties can
be further improved. The reason is as follows. Silk yarn consists of fibroin fibers having a
substantially triangular cross-sectional shape covered with sericin. The fibroin fiber itself has the
property of being easy to be tightly bound at the time of molding, and has a soft and high elastic
modulus. However, when sericin covers fibroin fibers and is present on the outer surface like
ordinary silk, it acts like an adhesive and bundles fibroin, which inhibits tight binding at the time
of forming and processing. . Therefore, by removing sericin, fibroin fibers are bound and densely
shaped without sterically hindered by sericin, so the elastic modulus of the obtained non-woven
fabric is significantly improved, and at the same time, fibroin fibers (protein It is possible to
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sufficiently and efficiently exhibit the excellent vibration damping ability effect that the fiber has.
Furthermore, when the non-woven fabric thus obtained has a densely bonded structure, when
impregnated with the same amount of thermosetting resin, the fiber volume ratio can be made
higher than that of a normal non-woven fabric. As a result, in the obtained diaphragm, the
flexible and high elastic modulus characteristics of the fibroin fibers appear more effectively, so
that a speaker diaphragm having a high elastic modulus and excellent acoustic characteristics
can be obtained. The above action can be sufficiently exhibited by removing sericin until the
sericin content of the silk thread is 1% by weight or less. The above-mentioned softness and
elastic modulus are particularly good, and the formability at the time of forming into a nonwoven fabric is also particularly good, when the fiber strength of the silk yarn is in the range of
0.8 to 1.2 denier. Furthermore, since the non-woven fabric formed using such fine fibers has a
large space portion, the unsaturated polyester resin can be easily impregnated with excellent
workability.
[0018]
In another aspect of the present invention, by providing a plurality of non-woven fabric layers,
the resin intervenes between the non-woven fabric layers and the non-woven fabric layers.
Therefore, a layer with a high fiber density (non-woven fabric layer) and a layer with a low fiber
density (resin layer intruded into the non-woven fabric layer) are formed in the thickness
direction of the laminate. As a result, since displacement of layers having large fiber density
occurs in the thickness direction of the obtained speaker diaphragm, internal loss can be
increased. According to a preferred embodiment, by providing a silk non-woven layer and an
organic non-woven layer, the surface of the speaker diaphragm is provided with the excellent
acoustic properties of the silk, and at the same time, the high tensile modulus organic fiber is
attributed to the excellent tensile strength. Excellent shape retention and mechanical strength
can be imparted to the entire diaphragm. By alternately providing the silk non-woven fabric layer
and the organic non-woven fabric layer, the acoustic characteristics and mechanical strength of
the diaphragm can be further improved. According to a preferred embodiment, by making the
non-woven fabric mesh-like, it is possible to prevent undesired deformation at the time of
forming the diaphragm. The details are as follows. Since the nonwoven fabric inevitably has a
strength aspect ratio of 2 or more due to the manufacturing method, undesired deformation
(distortion) occurs at the time of forming the diaphragm due to such strength anisotropy. For
example, when forming the diaphragm into a cone shape, the non-woven fabric is usually
stretched by about 20%, but if the strength aspect ratio is 2 or more, the non-woven fabric is not
uniformly stretched and distortion occurs. Therefore, it is important to make the aspect ratio of
the strength of the non-woven fabric as close to one as possible. When the non-woven fabric is
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formed in a mesh shape, the pores constituting the mesh relieve the stress at the time of molding
(at the time of elongation) and bear most of the expansion and contraction of the non-woven
fabric. As a result, uneven deformation at the time of molding is significantly prevented. In fact, it
has been confirmed that even if the nonwoven fabric is stretched by about 20%, almost no
difference in strength between the longitudinal and lateral directions is recognized (the aspect
ratio is approximately 1). According to a preferred embodiment, the addition of the rod-like
mineral to the thermosetting resin composition can improve the Young's modulus, the internal
loss, and the uniformity of deformation at the time of molding. The rod-like mineral has a smaller
anisotropy than a needle-like filler, so the distortion at the time of molding is small, and the
friction is larger than a spherical filler, so the internal loss is large. Furthermore, since the rodlike mineral is excellent in the dispersibility as a filler, it is also effective in improving the Young's
modulus. Preferably, the mossy mineral is graphite. Graphite is a crystal of carbon and has a
layered structure, and it has lubricity as well as conductivity, so slipperiness and dispersibility are
particularly excellent.
For example, when a thermosetting resin composition is coated on a non-woven fabric and pressmolded, the coated resin composition is compressed with a mold at the time of heat pressing, so
that it penetrates from the non-woven surface to the inside and reaches the back. Then it sticks
out and hardens. Also in such a case, the slipperiness and the dispersibility of the graphite are
very good. According to a preferred embodiment, the thermosetting resin composition further
contains a microballoon. By using the microballoon, weight saving can be achieved while
maintaining the excellent characteristics of the diaphragm of the present invention. Typically, the
microballoon is an organic microballoon having a vinylidene chloride-acrylonitrile copolymer as
a main component or an inorganic microballoon having a borosilicate glass as a main component.
Because these microballoons have particularly good dispersibility, their combination with other
additives is very easy. Therefore, a wide range of blending according to the purpose is possible.
[0019]
EXAMPLES The present invention will be specifically described by way of the following examples,
but the present invention is not limited to these examples.
[0020]
(Example 1) After short fibers of silk (fiber length 58 mm, 1.2 denier, the same applies
hereinafter) are randomly oriented by an air flow by a dry method to form an accumulation layer,
the fibers are further machined by water flow entanglement It was entangled to make a
nonwoven fabric weighing 150 g / m 2.
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The non-woven fabric was coated with unsaturated polyester solution a shown in Table 1 below
at a density of about 125 to 150 g / m 2, heat pressed at 110 ° C. for 1 minute, and having a
diameter of 16 cm and a thickness of 0.23 mm I got a diaphragm. With respect to the obtained
diaphragm, Young's modulus, density, specific modulus, internal loss and fiber deposition ratio
were measured by a conventional method. The measurement results are shown in Table 2 below
together with the results of Examples 2 to 4 and Comparative Examples 1 to 3 described later.
[0023] EXAMPLE 2 A speaker diaphragm was obtained in the same manner as in Example 1
except that refining was performed by boiling with weakly alkaline hot water and silk thread with
a sericin content of 1% or less was used. The obtained diaphragm was subjected to the same
measurement as in Example 1. The results are shown in Table 2 above.
[0024] Comparative Example 1 A speaker diaphragm was obtained in the same manner as in
Example 1 except that short fibers of PET (fiber length 38 mm) were used. The obtained
diaphragm was subjected to the same measurement as in Example 1. The results are shown in
Table 2 above.
[0025] Example 3 A nonwoven fabric weighing 30 g / m 2 was prepared using the silk yarn of
Example 2 and five layers of these nonwoven fabrics were laminated so that the direction
deviates by 30 degrees in plan view. A speaker diaphragm was obtained in the same manner as
in Example 1. The obtained diaphragm was subjected to the same measurement as in Example 1.
The results are shown in Table 2 above.
[0026] EXAMPLE 4 A speaker diaphragm was prepared in the same manner as in Example 1
except that the unsaturated polyester solution b shown in Table 1 was applied to the laminated
nonwoven fabric of Example 3 at a density of about 125 to 150 g / m 2. Obtained. The obtained
diaphragm was subjected to the same measurement as in Example 1. The results are shown in
Table 2 above. Comparative Example 2 A speaker diaphragm was obtained in the same manner
as in Example 1 except that the non-woven fabric was formed by the needle punch method. The
obtained diaphragm was subjected to the same measurement as in Example 1. The results are
shown in Table 2 above. (Comparative Example 3) After short fibers of silk (fiber length 58 mm)
are randomly oriented by air flow by a dry method to form an accumulation layer, the fibers are
mechanically entangled by water flow entanglement to weigh 150 g / m 2 Made of non-woven
fabric. Three layers (about 150 g / m 2) of prepreg sheet made of epoxy resin were thermally
transferred on both sides of this nonwoven fabric to prepare a nonwoven fabric prepreg sheet.
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This sheet was hot pressed at 150 ° C. for 15 minutes to obtain a speaker diaphragm. The
obtained diaphragm was subjected to the same measurement as in Example 1. The results are
shown in Table 2 above. As is clear from Table 2 above, the diaphragms of Examples 1 to 4 using
silk thread are superior to the diaphragms of Comparative Examples 1 to 3 in both Young's
modulus and internal loss. Furthermore, from the results of Examples 2 to 4, it is understood that
Young's modulus and internal loss are further improved by using the silk yarn from which sericin
has been removed. Further, from the results of Examples 3 and 4, it can be seen that the fiber
deposition ratio and the internal loss are significantly improved by using the laminated
nonwoven fabric. As apparent from the comparison between Examples 1 to 4 and Comparative
Example 3, according to the example of the present invention using an unsaturated polyester
resin, heat press molding can be performed in a much shorter time as compared with the case of
using an epoxy resin. It turns out that it is possible. Therefore, it can be seen that the speaker
diaphragm of the present invention is remarkably superior in manufacturing efficiency as
compared with a diaphragm using an epoxy resin. Furthermore, according to the present
invention, since heat press molding is possible at a much lower temperature than in the case of
using an epoxy resin, the silk thread is not adversely affected. As a result, Young's modulus,
specific modulus of elasticity and internal loss are significantly superior to Comparative Example
3 using an epoxy resin. Silk yarn begins to decompose at 120 ° C. and ammonia begins to be
generated at 130 ° C. or higher. Therefore, when heat-pressed using an epoxy resin, the
characteristics of silk deteriorate. In addition, according to the present invention, the operability
at the time of manufacture is remarkably improved as compared with Comparative Example 3.
Since epoxy resin has high viscosity at low temperature, it is difficult to handle complicated
operation (for example, applying a certain thickness to release paper with a doctor blade and
semi-curing: B-staging) to impregnate the fixed amount While this has to be done in context, such
operations are not required in the present invention. Furthermore, when it is necessary to mold
at low temperature, it is difficult to add various additives to the epoxy resin, so when using the
epoxy resin, it is difficult to improve the characteristics according to the purpose. I also knew
that.
[0027] Example 5 A silk non-woven fabric was produced in the same manner as in Example 2
except that the weight was 35 g / m 2. On the other hand, a non-woven fabric (weighing 70 g /
m 2) was prepared in the same manner as in Example 1 except that a meta-aramid fiber
(manufactured by Teijin Limited: Cornex, fiber length 38 mm) was used. A three-layered
laminated non-woven fabric comprising two silk non-woven fabric layers and an aramid nonwoven fabric layer sandwiched between the two layers was prepared, and a speaker diaphragm
was obtained in the same manner as in Example 1 thereafter. The Young's modulus, the density,
the specific elastic modulus and the internal loss of the obtained diaphragm were measured by a
conventional method. Furthermore, the deformation ratio was determined from the following
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equation: {(major axis-minor axis) / (regular dimension)} x 100 where the major axis and minor
axis are the major axis and the major axis of the diaphragm that became elliptical due to
deformation during molding. It is short diameter. These results are shown in the following Table
3 together with the results of Examples 6 to 9 described later.
[0029] EXAMPLE 6 A speaker diaphragm was prepared in the same manner as in Example 5
except that para-aramid fiber (made by Toray DuPont Co., Ltd .: Kevlar, fiber length 38 mm) was
used instead of meta-aramid fiber. I got The obtained diaphragm was subjected to the same
measurement as in Example 5. The results are shown in Table 3 above.
[0030] (Example 7) A speaker diaphragm was obtained in the same manner as in Example 5
except that PET fibers were used instead of the meta-aramid fibers. The obtained diaphragm was
subjected to the same measurement as in Example 5. The results are shown in Table 3 above.
[0031] Example 8 A mesh-type non-woven fabric was prepared by hydroentanglement of metaaramid fibers using a # 16 mesh net. The speaker diaphragm was obtained like Example 5 except
having used this mesh-like nonwoven fabric. The obtained diaphragm was subjected to the same
measurement as in Example 5. The results are shown in Table 3 above.
[0032] Example 9 A speaker diaphragm was obtained in the same manner as in Example 8
except that the unsaturated polyester resin solution b was used instead of the unsaturated
polyester resin solution a. The obtained diaphragm was subjected to the same measurement as in
Example 5. The results are shown in Table 3 above. As is clear from Table 3 above, it can be seen
that the speaker diaphragms of Examples 5 to 9 all have excellent characteristics. For example,
the diaphragm of Example 5 using a meta-aramid fiber is particularly excellent in deformation
ratio, and the diaphragm of Example 6 using a para-aramid fiber is particularly excellent in
Young's modulus and specific modulus. The Young's modulus of silk fibers is 8.8-13.8 × 10 10
dyn / cm 2, while the Young's modulus of meta-aramid fibers is 7.3 × 10 10 dyn / cm 2, and the
Young's modulus of para-aramid fibers is The para-aramid fiber is preferable from the viewpoint
of combining the non-woven fabrics using fibers with approximated Young's modulus to obtain a
diaphragm excellent in the balance of various properties, since it is 5.8 × 10 11 dyn / cm 2. The
Young's modulus of PET fiber is 1.23 × 10 11 dyn / cm 2. In Example 5 in which three layers of
meta-aramid fibers are used, physical properties substantially equivalent to those in Example 3 in
which five layers of silk fibers are used can be obtained, and the number of layers can be
reduced. The workability at the time of diaphragm production can be improved. In addition,
regarding the deformation rate at the time of molding, it can be seen that deformation is
particularly small when using a mesh-like non-woven fabric, which is preferable.
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[0033] (Example 10) After short fibers of silk (fiber length 58 mm) are randomly oriented by air
flow by dry method to form an accumulation layer, the fibers are mechanically entangled by
water flow entanglement to weigh 30 g / m 2 Made of non-woven fabric. Six layers of this nonwoven fabric are laminated, and the unsaturated polyester solution c shown in Table 1 is applied
at a density of about 125 to 150 g / m 2 on both sides of the laminate, and 110 ° using a
diaphragm-shaped mat die die. Hot press molding for 1 minute at C. As a result, a speaker
diaphragm having a diameter of 20 cm and a thickness of 0.35 mm was obtained. With respect
to the obtained diaphragm, Young's modulus, density, specific modulus, internal loss and aspect
ratio were measured by a conventional method. These results are shown in Table 4 below
together with the results of Example 11 and Comparative Examples 4 to 5 described later.
Furthermore, the content of the scaly graphite in the unsaturated polyester solution c was
changed to prepare a diaphragm, and their Young's modulus was measured. The relationship
between the graphite content and the Young's modulus is shown in FIG.
[0035] Comparative Example 4 A speaker diaphragm was obtained in the same manner as in
Example 10 except that the unsaturated polyester solution d shown in Table 1 was used. The
obtained diaphragm was subjected to the same measurement as in Example 10. The results are
shown in Table 4 above.
[0036] Example 11 A speaker diaphragm was obtained in the same manner as in Example 10
except that the coating density of the unsaturated polyester solution c was changed to about 60
to 75 g / m 2. The obtained diaphragm was subjected to the same measurement as in Example
10. The results are shown in Table 4 above.
[0037] Comparative Example 5 A speaker diaphragm was obtained in the same manner as in
Example 10 except that the unsaturated polyester solution e shown in Table 1 was used. The
obtained diaphragm was subjected to the same measurement as in Example 10. The results are
shown in Table 4 above. As apparent from the comparison of Examples 10 and 11 with
Comparative Example 4 in Table 4, both the Young's modulus and the internal loss are
remarkably improved by using the scaly graphite. As is clear from the comparison of Examples
10 and 11 with Comparative Example 5, it can be seen that if the particle size of the scaly
graphite is too large, the inclusion of scaly graphite does not have much effect. Further, as
apparent from FIG. 2, it is understood that the content of the graphite is preferably 20 to 50
parts by weight with respect to 100 parts by weight of the unsaturated polyester resin. (Example
12) After short fibers of silk (fiber length 58 mm) are randomly oriented by air flow according to
a dry method to form an accumulation layer, the fibers are mechanically entangled by water flow
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entanglement to weigh 30 g / m 2 Made of non-woven fabric. Six layers of this non-woven fabric
are laminated, and the unsaturated polyester solution f shown in Table 1 is applied at a density of
about 60 to 75 g / m 2 on both sides of the laminate, and 110 ° using a diaphragm-shaped
matched die mold. Hot press molding for 1 minute at C. As a result, a speaker diaphragm having
a diameter of 20 cm and a thickness of 0.35 mm was obtained. The Young's modulus, the
density, the specific elastic modulus and the internal loss of the obtained diaphragm were
measured by a conventional method. These results are shown in the following Table 5 together
with the results of Examples 13 to 16 described later.
[0039] EXAMPLE 13 A speaker diaphragm was obtained in the same manner as in Example 12
except that the unsaturated polyester solution g shown in Table 1 was used. The obtained
diaphragm was subjected to the same measurement as in Example 12. The results are shown in
Table 5 above. Furthermore, the content of hollow spheres (microballoons) in unsaturated
polyester solution g was changed to prepare diaphragms, and their Young's modulus and internal
loss were measured. The relationship between the balloon content and the Young's modulus is
shown in FIG. 3 (a), and the relationship between the balloon content and the internal loss is
shown in FIG. 3 (b).
[0040] EXAMPLE 14 A speaker diaphragm was obtained in the same manner as in Example 12
except that the unsaturated polyester solution h shown in Table 1 was used. The obtained
diaphragm was subjected to the same measurement as in Example 12. The results are shown in
Table 5 above.
[0041] EXAMPLE 15 A speaker diaphragm was obtained in the same manner as in Example 12
except that the unsaturated polyester solution i shown in Table 1 was used. The obtained
diaphragm was subjected to the same measurement as in Example 12. The results are shown in
Table 5 above.
[0042] EXAMPLE 16 A speaker diaphragm was obtained in the same manner as in Example 12
except that the above unsaturated polyester solution a was used. The obtained diaphragm was
subjected to the same measurement as in Example 12. The results are shown in Table 5 above.
As apparent from Table 5, it can be seen that the speaker diaphragms of Examples 12 to 16 all
have excellent characteristics. Furthermore, it can be seen that by using the microballoon, it is
possible to reduce the density (weight) while maintaining excellent Young's modulus, specific
modulus or internal loss. As apparent from FIGS. 3A and 3B, it is understood that the balloon
content is preferably in the range of 5 to 20 parts by weight in consideration of the balance
between Young's modulus and internal loss.
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[0043] As described above, according to the present invention, by using a combination of protein
fiber and unsaturated polyester resin, a loudspeaker diaphragm having very excellent acoustic
characteristics can be obtained with very high production efficiency. be able to.
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