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JP2011114409

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DESCRIPTION JP2011114409
Abstract: To provide a speaker diaphragm having excellent formability, light weight, high rigidity,
and good frequency characteristics with respect to acoustic characteristics. A foam layer and a
pair of glass cloths integrated with the foam layer so that intersections of warps and wefts are
exposed on the surface layer portions on both main surfaces of the foam layer. , To constitute a
speaker diaphragm. [Selected figure] Figure 2
Speaker diaphragm and method of manufacturing the same
[0001]
The present invention relates to a speaker diaphragm particularly useful for flat type speakers,
and a method of manufacturing the same, and particularly to a speaker diaphragm having
excellent formability, light weight, high rigidity, and good frequency characteristics regarding
acoustic characteristics. And a method of manufacturing the same.
[0002]
Conventionally, various materials are used for the speaker diaphragm according to the
application.
For example, in order to improve the insufficient strength of the speaker diaphragm used for a
cone-type speaker of an audio device, a natural fiber and a chemical fiber are entangled in a
woven fabric of high strength fibers such as aramid fibers, carbon fibers and glass fibers The
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following is proposed (Patent Document 1). However, such a diaphragm has low strength, and
the vibration characteristic of the high range is not satisfactory.
[0003]
For this reason, the base fabric is formed by volatilizing or decomposing the oil agent attached to
the inorganic fiber woven fabric prior to the heat treatment by subjecting the woven fabric
formed by impregnating the rigid inorganic fiber with the resin to heat treatment in advance.
Unlike this base fabric, it is bonded with a diaphragm made of a material with a smaller density
and a large internal loss with an adhesive and fixed to each other by a heat press, resulting in
high sensitivity, a wide reproduction frequency band, and harmonics. It has been proposed to
provide a diaphragm for a cone type speaker having acoustic characteristics such as little
distortion (Patent Document 2). However, since such a diaphragm has a resin-impregnated
inorganic fiber woven fabric disposed on the surface, the resin layer having a low elastic modulus
covers the surface of the diaphragm, so that the sound pressure characteristics are low. was
there.
[0004]
From such a point of view, in order to improve the vibration characteristics of the high sound
range, it comprises: a woven fabric in which the impregnated thermosetting resin is in a
thermosetting state; A diaphragm for a cone-type speaker excellent in vibration characteristics in
a high range by proposing a texture of the woven fabric is proposed (Patent Document 3).
However, after impregnating a thermosetting resin into a woven fabric to form a prepreg, it has
been very difficult to form the woven fabric so as to expose only the weave of the woven fabric to
the surface side.
[0005]
Moreover, when using the diaphragm mentioned above for flat type speakers, intensity was weak
and it was not able to fully satisfy range characteristics. In order to increase the strength, it is
conceivable to use glass fibers as the inorganic fiber woven fabric. However, it is necessary to
increase the thickness of the glass fiber, which causes a problem that the specific gravity of the
entire diaphragm is increased to cause a decrease in sound pressure characteristics.
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[0006]
Japanese Patent Application Laid-Open No. 63-70786 Japanese Patent Laid-Open No. 200092590 Japanese Patent Laid-Open No. 2009-21832
[0007]
The present invention has been made to solve the above problems, and is particularly suitable for
use as a flat speaker, having excellent formability, light weight, high rigidity, and good frequency
characteristics with respect to acoustic characteristics. It aims at providing a board and its
manufacturing method.
[0008]
In order to achieve the above object, the present invention is integrated with the foam layer so
that the intersection points of the warp and the weft are exposed on the surface layer portions of
the foam layer and both main surfaces of the foam layer. And a pair of the glass cloths.
[0009]
The present inventors diligently studied to achieve the above object.
As a result, the speaker diaphragm is structured with the glass cloth layers disposed on both
principal surfaces of a specific foam layer, and only the intersections of the warps and wefts of
the glass cloth are exposed on the surface. By forming the diaphragm, it has been found that it
has excellent formability, light weight, high rigidity, and good frequency characteristics with
respect to acoustic characteristics, thereby completing the present invention.
[0010]
The formability, lightness, and high rigidity are considered to be due to the material composition
of the above-described speaker diaphragm, but the frequency characteristics are that only the
intersection points of the glass cloth warp and weft are exposed on the surface. It is thought that
it originates in.
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However, the detailed effects are not clear at present.
[0011]
In one example of the present invention, the foam layer is formed of a matrix containing a
thermosetting resin and a hollow spherical inorganic substance, and a volatile liquid foaming
agent in an outer shell made of a thermoplastic resin and encapsulated in the matrix. A foamable
resin composition containing thermally expandable microcapsules, wherein the content of the
hollow spherical inorganic material in the foamable resin composition is 1% by mass to 60% by
mass, The content of the thermally expandable microcapsule is preferably 1% by mass to 10% by
mass.
By using the foamable resin composition that satisfies the above-described requirements, the
speaker diaphragm of the above-described configuration can be easily formed.
[0012]
Moreover, in another example of the present invention, the hollow spherical inorganic material
preferably contains at least one selected from the group consisting of a glass balloon, a shirasu
balloon, and a silica-alumina balloon. By using these substances, the hollow spherical inorganic
substance can be easily formed.
[0013]
In still another example of the present invention, the thermally expandable microcapsules
preferably have an average particle diameter of 2 μm to 50 μm in an unexpanded state. Thus,
when manufacturing the speaker diaphragm described above by the manufacturing method
described in detail below, it is possible to easily form the speaker diaphragm having the abovedescribed configuration, and to suppress characteristic deterioration such as surface smoothness.
can do.
[0014]
Moreover, in the other example of this invention, it is preferable that expansion | swelling start
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temperature is 70 degreeC-150 degreeC, and the said thermal expansion microcapsule is 150
degreeC-200 degreeC in largest expansion temperature.
[0015]
By setting the expansion start temperature in the former range, the thermally expandable
microcapsules do not expand at the time of preparation of the foamable resin composition, and
expansion occurs at a temperature when forming the speaker diaphragm by molding or the like.
As a result, the above-mentioned diaphragm for a speaker can be manufactured without any
problems.
[0016]
Furthermore, by setting the maximum thermal expansion temperature in the latter range, the
maximum temperature at the time of formation, that is, the temperature at which the foam layer
and the glass cloth are integrated, as described in detail below, The degree of expansion of the
thermally expandable microcapsules in the medium can be made as designed.
That is, since the degree of expansion of the thermally expandable microcapsule can be made as
designed by utilizing the temperature at the time of formation, it is necessary to separately
perform a heat treatment etc. in order to make the degree of expansion of the thermally
expandable microcapsule as designed. There is no
Therefore, the manufacturing process at the time of manufacturing the diaphragm for speakers
can be simplified.
[0017]
Furthermore, in another example of the present invention, it is preferable that the density of the
diaphragm is 0.2 g / cm <3> to 1.0 g / cm <3> and the elastic modulus is 3 GPa to 15 GPa. By
setting such a range of characteristics, good frequency characteristics are exhibited, and acoustic
characteristics become excellent. The relationship between these physical property values and
the acoustic characteristics is not clear at present.
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[0018]
The speaker diaphragm of the present invention can be manufactured by any method, and for
example, can be manufactured by the manufacturing method as shown below.
[0019]
That is, between the pair of glass cloths, a base material containing a thermosetting resin and a
hollow spherical inorganic substance, and a volatile liquid foaming agent contained in an outer
shell made of a thermoplastic resin contained in the base material Foamable, wherein the content
of the hollow spherical inorganic material is 1% by mass to 60% by mass, and the content of the
thermally expandable microcapsules is 1% by mass to 10% by mass The first step of disposing a
resin composition, and heating the pair of glass cloth and the foamable resin composition above
the thermal expansion start temperature of the thermally expandable microcapsule to foam the
foamable resin composition And a second step of fusing the pair of glass cloths and the foamable
resin composition such that the intersections of the warps and wefts of the pair of glass cloths
are exposed on the surface. The The butterfly, is a manufacturing method of the speaker
diaphragm.
[0020]
According to the present invention, it is possible to provide a speaker diaphragm having light
weight, high rigidity, and good frequency characteristics with respect to acoustic characteristics.
Further, according to the present invention, it is possible to provide a manufacturing method for
easily manufacturing a speaker diaphragm having such a characteristic.
[0021]
It is a top view of the diaphragm for speakers in an embodiment.
It is sectional drawing at the time of cutting the diaphragm for speakers shown in FIG. 1 along an
AA. It is sectional drawing at the time of cutting the diaphragm for speakers shown in FIG. 1
along a BB line. It is explanatory drawing regarding the manufacturing method of the diaphragm
for speakers in embodiment. It is explanatory drawing regarding the manufacturing method of
the diaphragm for speakers in embodiment. It is a graph which shows the measurement result of
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the output sound pressure frequency characteristic of the diaphragm for speakers of an Example
and a comparative example. It is a graph which shows the measurement result of the output
sound pressure frequency characteristic of the diaphragm for speakers of an Example.
[0022]
The details of the present invention, as well as other features and advantages thereof, are
described below with reference to the drawings.
[0023]
(Speaker Diaphragm) FIG. 1 is a plan view of the speaker diaphragm in the present embodiment,
and FIG. 2 is a cross-sectional view of the speaker diaphragm shown in FIG. 1 cut along the line
A-A. FIG. 3 is a cross-sectional view of the speaker diaphragm shown in FIG. 1 cut along the line
B-B.
[0024]
As shown in FIGS. 1 to 3, the speaker diaphragm 1 of the present embodiment has a foam layer 2
and a pair of glass cloths 3 arranged on both main surface sides of the foam layer 2. The cross
points 3A and 3B of the warp and weft of each glass cloth 3 are exposed on the front and back
surfaces.
In addition, in FIG. 1, the state by the side of one main surface is shown.
[0025]
In this embodiment, the speaker diaphragm has a structure including the glass cloth layers
disposed on both principal surfaces of a specific foam layer, so that only the intersection points
of the warp and the weft of the glass cloth are exposed on the surface. By forming the speaker
diaphragm, it has excellent formability, light weight, high rigidity, and good frequency
characteristics with respect to acoustic characteristics.
[0026]
The formability, lightness, and high rigidity are considered to be due to the material composition
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of the above-described speaker diaphragm, but the frequency characteristics are that only the
intersection points of the glass cloth warp and weft are exposed on the surface. It is thought that
it originates in.
However, the detailed effects are not clear at present.
[0027]
Although it does not specifically limit about the glass fiber to be used, High-strength glass cloth,
such as E glass, T glass, S glass, R glass, can use it preferably.
The focusing number of the glass fibers is not particularly limited, but 100 to 200 usually used
can be preferably used.
[0028]
The weave density of the glass cloth is preferably 10 to 100 per inch, and more preferably 20 to
60. If the weave density is less than 10 per inch, the elastic modulus of the diaphragm is low, and
if it is more than 100, the specific gravity of the diaphragm is increased, which is not preferable
because the sound pressure characteristics deteriorate.
[0029]
The ratio of the warp to the weft of the glass cloth is appropriately determined according to the
density of intersections to be exposed on the surface. For example, the range of 0.4-1.5,
preferably the range of 0.8-1.3 is desirable. If the thickness is out of the range of 0.4 to 1.5, the
density of the woven fabric may be too coarse or too dense, and the sound pressure
characteristics may be deteriorated.
[0030]
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The weave of the glass cloth is not particularly limited, but plain weave is particularly preferable
because of high effective intersection density. That is, by using plain weave, it is possible to easily
form the desired number of intersection densities.
[0031]
The thickness of the glass cloth is not particularly limited, but is preferably 2.5% to 25% with
respect to the total thickness of the diaphragm. When the thickness of the glass cloth is thinner
than 2.5%, the elastic modulus is low, and when it is thicker than 25%, the elastic modulus
becomes high but the weight increase makes the sound pressure characteristics worse, which is
not preferable. By setting the glass cloth in the above range, a diaphragm having an appropriate
elastic modulus can be obtained.
[0032]
The foam layer 2 is, for example, a base material containing a thermosetting resin and a hollow
spherical inorganic substance, and a thermal liquid formed by containing a volatile liquid
foaming agent in an outer shell made of a thermoplastic resin contained in the base material. An
expandable resin composition comprising expandable microcapsules, wherein the content of the
hollow spherical inorganic substance in the expandable resin composition is 1% by mass to 60%
by mass, and the thermally expandable microcapsules It is preferable that content is 1 mass%-10
mass%. By using the foamable resin composition that satisfies the above-described requirements,
the speaker diaphragm of the above-described configuration can be easily formed. The details of
the foamable resin composition are as described below.
[0033]
The thermosetting resin in the foamable resin composition may be any resin containing at least
an epoxy resin, and may be made of, for example, only an epoxy resin, or, for example, an epoxy
resin and other thermosetting resins. And may be composed of
[0034]
As an epoxy resin, what contains 2 or more epoxy groups in 1 molecule is preferable, for
example, bisphenol A epoxy resin, bisphenol F epoxy resin, bisphenol AD (acetaldehyde) epoxy
resin, glycidyl ester epoxy resin, fat A cyclic epoxy resin etc. are mentioned, These can be used
individually or in mixture of 2 or more types.
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[0035]
It is also possible to use mixtures of these epoxy resins mixed with epoxy resins of other groups
or types, or their mutual reactants.
As the epoxy resin of other group or type, for example, phenol novolac epoxy resin, cresol
novolac epoxy resin, heterocyclic epoxy resin, hydrogenated (hydrogenated) bisphenol A epoxy
resin, aliphatic epoxy resin, aromatic Epoxy resins, spirocyclic epoxy resins, etc. obtained by the
reaction of a group, aliphatic or alicyclic carboxylic acid with epichlorohydrin can be used.
[0036]
On the other hand, as thermosetting resin other than an epoxy resin, a phenol resin, polyacetal
resin, unsaturated polyester resin, a polyimide resin etc. are mentioned, for example, These can
be used individually or in mixture of 2 or more types.
[0037]
It is preferable to make the foamable resin composition contain a curing agent capable of
reacting with the thermosetting resin to form a cured product, corresponding to such a
thermosetting resin.
The curing agent is not particularly limited as long as it can react with a thermosetting resin to
form a cured product. For example, as a curing agent for epoxy resin, acid anhydride such as
methyl hexahydrophthalic anhydride , Phenolic resins such as novolac type phenolic resin, cresol
novolac type epoxy resin, phthalic anhydride derivatives, dicyandiamide, imidazole compounds,
aluminum chelates, amine complexes of Lewis acids such as BF3, etc. It is possible to use a
mixture of species and more.
[0038]
Although the content of the curing agent varies depending on the type of thermosetting resin, the
type of curing agent, etc., for example, the epoxy resin, although it varies depending on the epoxy
equivalent, is usually 2 parts by mass with respect to 100 parts by mass It is preferable to set it
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as a part-150 mass parts.
[0039]
The hollow spherical inorganic substance is added for the purpose of reducing the weight of the
foam layer 2 and the like, and various inorganic balloons, for example, ceramic balloons such as
glass balloon, shirasu balloon, fly ash, silica-alumina balloon etc. These can be used alone or in
combination of two or more.
Among these, it is particularly preferable to use a glass balloon.
These substances are easily available, and can easily constitute the above-mentioned hollow
spherical inorganic substance.
[0040]
The average particle size of the hollow spherical inorganic material is preferably 30 μm to 150
μm. When the average particle diameter of the hollow spherical inorganic material exceeds 150
μm, it is not preferable because it is easily broken at the time of formation for obtaining the
speaker diaphragm 1 and the surface of the foam layer 2 becomes rough. In addition, when the
average particle diameter of the hollow spherical inorganic material is less than 30 μm, the
formability of the foamable resin composition is reduced, which makes it difficult to manufacture
the diaphragm 1 for a speaker, and per unit volume in the foam layer 2 There is a possibility that
weight reduction may become difficult because the content is increased.
[0041]
The content of the hollow spherical inorganic substance is 1% by mass or more and 60% by mass
or less, preferably 5% by mass or more and 50% by mass or less in the whole of the foamable
resin composition. When the content of the hollow spherical inorganic material is less than 1% by
mass, it may be difficult to reduce the weight and increase the rigidity of the foam layer 2, and
when it exceeds 60% by mass, the formability of the foamable resin composition is The content
of the heat-expandable microcapsules may be relatively reduced, and the thermal expansion
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thereof may also be inhibited.
[0042]
The apparent density of the hollow spherical inorganic material is preferably 0.2 g / cm <3> to
0.7 g / cm <3>. When the apparent density of the hollow spherical inorganic material is less than
0.2 g / cm <3>, it is easily broken at the time of molding for obtaining the speaker diaphragm 1,
and if it exceeds 0.7 g / cm <3>, the foam layer It may be difficult to reduce the weight of 2. By
setting the apparent density of the hollow spherical inorganic substance in the above range, the
foam layer 2 can be made light in weight and high in rigidity while the moldability of the
foamable resin composition is improved.
[0043]
In addition, it is preferable that the said hollow spherical inorganic substance is surface-treated
from a viewpoint of improving adhesiveness with a thermosetting resin. As a surface treatment
agent, an organic silane compound, an organic titanate compound, or an organic aluminate
compound is mentioned, for example, These can be used individually or in mixture of 2 or more
types.
[0044]
Examples of the organic silane compounds include vinyltriethoxysilane, vinyl-tris- (2methoxyethoxy) silane, γ-methacryloxypropylmethoxysilane, γ-aminopropyltrimethoxysilane,
N-β- (aminoethyl)- γ-aminopropyltrimethoxysilane, β- (3,4-epoxycyclohexyl)
ethyltriethoxysilane, γ-glycidoxypropylmethoxysilane, γ-mercaptopropyltrimethoxysilane etc.
may be mentioned alone or It is possible to use a mixture of species and more.
[0045]
Examples of organic titanate compounds include tetra-i-propyl titanate, tetra-n-butyl titanate,
butyl titanate dimer, tetrastearyl titanate, triethanolamine titanate, titanium acetylacetonate,
titanium lactate, octylene glycol titanate, isopropyl ( N-aminoethylaminoethyl) titanate etc. are
mentioned, These can be used individually or in mixture of 2 or more types.
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Moreover, as an organic aluminate compound, an aceto alkoxy aluminum diisopropylate etc. are
mentioned, for example.
[0046]
The surface treatment of the hollow spherical inorganic substance can be carried out by a
conventional method, for example, the surface treatment agent may be dissolved in water or
various organic solvents, and the hollow spherical inorganic substance may be dipped and dried
in this. For example, while heating and stirring the hollow spherical inorganic material in a mixer
such as a Henschel mixer, a solution of the surface treatment agent in water or various organic
solvents may be added little by little.
[0047]
The thermally expandable microcapsules forming the expandable resin composition (in FIGS. 2
and 3, the thermally expandable microcapsules after expansion are indicated by reference
numeral "6") expand due to the heat at the time of formation. Yes, while reducing the weight of
the speaker diaphragm 1, as described above, the crossing points 3A and 3B of the warp and
weft of the glass cloth 3 are exposed on the front and back surfaces, and the frequency
characteristics are good with respect to acoustic characteristics. To be added to have
[0048]
The thermally expandable microcapsule is composed of a volatile liquid foaming agent and an
outer shell composed of a thermoplastic resin containing the volatile liquid foaming agent inside.
Specifically, a volatile liquid foaming agent that volatilizes at a heating temperature when
forming a diaphragm is wrapped in an outer shell made of a thermoplastic resin which is
softened at the temperature.
By setting it like this, it can be made to expand | swell appropriately by the heat at the time of
formation, and, thereby, the foamable resin composition can be made into a foaming state.
[0049]
Thus, from the viewpoint of appropriately expanding at the forming temperature, the content of
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the thermally expandable microcapsule, that is, the content of the volatile liquid foaming agent in
the total amount of the volatile liquid foaming agent and the outer shell is 30% by mass or more
It is preferable that it is mass% or less.
[0050]
The expansion start temperature of the thermally expandable microcapsule is preferably 70 ° C.
or more.
When the expansion start temperature of the thermally expandable microcapsules is less than 70
° C., for example, the thermally expandable microcapsules may expand during mixing, kneading,
specifically when preparing the foamable resin composition. From the viewpoint of appropriately
expanding at the temperature at the time of formation, the expansion start temperature of the
thermally expandable microcapsule is preferably 150 ° C. or less.
[0051]
Therefore, the thermoplastic resin needs to be appropriately softened at the temperature at the
time of formation and expand by the volatilization of the volatile liquid foaming agent contained
therein, for example, at 70 ° C. Those which soften at a temperature of 150 ° C. are preferred.
Further, the thermoplastic resin constituting the outer shell is preferably one having a
sufficiently high viscosity at the temperature of formation so that the capsule state can be
maintained without rupture due to thermal expansion during formation.
[0052]
As a thing which satisfy | fills such conditions, the polymer of vinylidene chloride, an
acrylonitrile, methacritonitrile, or a methyl methacrylate, or these 2 or more types of copolymers,
for example, a vinylidene chloride-acrylonitrile copolymer, vinylidene chloride -AcrylonitrileMethyl methacrylate copolymer, Acrylonitrile-Methyl methacrylate copolymer, One or more of
these, and various monomers such as vinyl halide, styrenic monomer, vinyl acetate, butadiene,
vinyl pyridine, chloroprene and the like Copolymers may be mentioned.
[0053]
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The thermoplastic resin may be crosslinkable or crosslinkable with a crosslinking agent such as
divinylbenzene, ethylene glycol di (meth) acrylate, triethylene glycol di (meth) acrylate, triacrylic
formal, triallyl isocyanate and the like.
Among these thermoplastic resins, homopolymers of (meth) acrylonitrile having a high thermal
expansion start temperature and maximum expansion temperature, or a copolymer having a high
(meth) acrylonitrile content are preferably used.
[0054]
Examples of volatile liquid foaming agents include isobutane, isopentane, normal butane, normal
butane, normal pentane, neopentane, hexane, etc. which are liquid at normal temperature and
vaporize at the temperature at the time of formation. Among these, low boiling point
carbonization such as isobutane, isopentane and the like Hydrogen is preferred.
[0055]
As the volatile liquid foaming agent, other than those mentioned above can be used, for example,
specific freons such as dichlorofluoromethane, trichlorofluoromethane, dichlorofluoroethane,
dichlorotrifluoroethane, trichlorotrifluoroethane, dichloropentafluoropropane and the like And
alternative freons, hydrocarbons such as petroleum ether, and chlorinated hydrocarbons such as
methyl chloride, methylene chloride, dichloroethylene, trichloroethane, and trichloroethylene, but
not limited thereto.
[0056]
The average particle diameter of the thermally expandable microcapsule (outer shell) is
preferably 2 μm to 50 μm in the unexpanded state, more preferably 5 μm to 40 μm, and still
more preferably 10 μm to 30 μm or less.
If the average particle size of the thermally expandable microcapsules is smaller than the above
range, the expansion coefficient and expansion force at the time of formation may not be
sufficient, and if larger than the above range, the expansion coefficient and expansion force at
the time of formation Because the size is too large, the surface smoothness of the resulting foam
layer 2 may be reduced, and the mechanical strength of the speaker diaphragm 1 may not be
sufficient.
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[0057]
Furthermore, the maximum expansion temperature of the thermally expandable microcapsule,
that is, the temperature at which the expansion coefficient of the thermally expandable
microcapsule is maximized is preferably 150 ° C to 200 ° C.
In the present embodiment, as described above, since the foam layer 2 and the glass cloth 3 are
formed, the maximum temperature at the time of formation, that is, the temperature at which the
foam layer 2 and the glass cloth 3 are integrated is 150 ° C. Since the degree of expansion of
the thermally expandable microcapsule can be made as designed at -200 ° C., it is not necessary
to separately perform heat treatment etc. in order to make the degree of expansion of the
thermally expandable microcapsule as designed. Therefore, the manufacturing process at the
time of manufacturing the diaphragm for speakers can be simplified.
[0058]
The expansion start temperature and the maximum expansion temperature can be measured, for
example, by placing a thermally expandable microcapsule in a cylindrical aluminum container or
the like and applying a force from above using a TMA (manufactured by TA Instruments) from
above. Can be performed by measuring the amount of displacement of the pressure terminal in
the vertical direction, the temperature at which the displacement starts to be observed is taken as
the expansion start temperature, and the temperature at which the displacement becomes the
maximum is taken as the maximum expansion temperature. be able to.
[0059]
As such unexpanded thermally expandable microcapsules, those commercially available can be
suitably used, and examples thereof include EXPANCEL (manufactured by Nippon Fillite Co.,
Ltd.).
In this case, the outer shell is made of the above-mentioned vinylidene chloride-acrylonitrile
copolymer, acrylonitrile-methacrylonitrile copolymer or the like, and the volatile liquid foaming
agent is made of isobutane or isopentane or the like.
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[0060]
Specifically, product numbers 642, 551, 461 (shell: vinylidene chloride-acrylonitrile copolymer,
volatile liquid blowing agent; isobutane, thermal expansion onset temperature: about 90 ° C.
(item number 642), about 100 ° C (Item No. 551), about 110 ° C. (Item No. 461), Item Nos.
091, 092 (shell: acrylonitrile-methacrylonitrile copolymer, volatile liquid blowing agent;
isopentane, thermal expansion onset temperature: about 130 ° C) and the like. Since they
expand up to about 4 times in size, they expand up to about 60 times in volume.
[0061]
The content of the thermally expandable microcapsule is 1% by mass or more and 10% by mass
or less, more preferably 1% by mass or more and 5% by mass or less in the whole of the
foamable resin composition. If the content of the heat-expandable microcapsules is less than the
above range, the expansion coefficient and expansion force at the time of formation may not be
sufficient, and if the content of the heat-expandable microcapsules is more than the above range,
formation Since the expansion rate and expansion force at that time become too large, the
mechanical strength of the speaker diaphragm 1 may not be sufficient.
[0062]
In the foamable resin composition, in addition to the above-mentioned thermosetting resin and
the like, and to the extent not departing from the spirit of the present invention, other
components such as inorganic fillers, coupling agents, antifoaming agents, coloring agents, A
curing accelerator, a shape maintaining agent, etc. can be contained.
[0063]
Examples of the inorganic filler include powders of silica, alumina, talc, calcium carbonate,
titanium white, iron oxide, silicon carbide, boron nitride and the like, and these can be used alone
or in combination of two or more.
The average particle diameter of the inorganic filler is preferably 0.1 μm to 100 μm, and more
preferably 1 μm to 30 μm, from the viewpoint of the flowability of the foamable resin
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composition and the like.
[0064]
The preparation of the foamable resin composition can be carried out by applying a known
method for preparing a resin composition, for example, in addition to thermosetting resins,
hollow spherical inorganic substances, and thermally expandable microcapsules, if necessary. It
can carry out by mix | blending and knead | mixing the other component added. The mixing and
kneading for preparing the foamable resin composition is preferably performed at a temperature
lower than the thermal expansion start temperature of the thermally expandable microcapsule.
[0065]
The foam layer 2 obtained by foaming such a foamable resin composition preferably has a
thickness of, for example, 100 μm to 5000 μm. Moreover, it is preferable that the foaming ratio
of the foam layer 2 is 2-10. If the expansion ratio is smaller than the above range, the specific
gravity of the foam layer 2 may be excessively increased, and if it exceeds the above range, the
rigidity of the foam layer 2 may not be sufficient.
[0066]
Here, the expansion ratio is the density of the so-called unfoamed foam layer 2 in which the
thermally expandable microcapsules are not thermally expanded, and the density of the foamed
foam layer 2 in which the thermally expandable microcapsules are thermally expanded. From the
above, it is determined by "the density of the unfoamed foam layer 2 / the density of the foamed
foam layer 2". Incidentally, the expansion ratio is adjusted, for example, by adjusting the average
particle diameter, content and the like of the thermally expandable microcapsule, and, for
example, the forming conditions, specifically, the forming temperature, the forming time, the
forming pressure, It can be performed by adjusting the clearance and the like.
[0067]
In addition, the speaker diaphragm 1 including the foam layer 2 and the covering layer 3 has a
density of 0.2 g / m in terms of light weight, high rigidity, and good frequency characteristics
with respect to acoustic characteristics. It is preferable that it is cm <3> -1.0 g / cm <3>, it is
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preferable that an elasticity modulus (bending elastic modulus) is 2 GPa-15 GPa, More
preferably, it is 4 GPa-10 GPa.
[0068]
(Method of Manufacturing Speaker Diaphragm) Next, a method of manufacturing the speaker
diaphragm 1 shown in FIGS. 1 to 3 will be described.
[0069]
FIG. 4 shows an example of the manufacturing method.
In this manufacturing method, a pair of glass cloths 3 is first disposed on the opposing inner
surfaces 11a and 12a using a pair of upper and lower molding dies 11 and 12, respectively.
At this time, in the case where the glass cloth 3 is in the form of a sheet such as a metal foil, for
example, the glass cloth 3 can be disposed by being attached to the inner surfaces 11a and 12a.
As in the case of the paint-like one, it can be arranged by applying it to the inner surfaces 11a
and 12a.
[0070]
Thereafter, in the molding dies 11 and 12, the foamable resin composition 2a to be the foam
layer 2 is disposed between the pair of glass cloths 3 disposed opposite to each other on the
inner surfaces 11a and 12a. The foamable resin composition 2a may be applied to at least one of
the pair of glass cloths 3 after arranging the pair of glass cloths 3 inside the molding dies 11 and
12 as described above, It may be disposed by injection or the like in the molding dies 11 and 12.
Moreover, before arranging in the molding dies 11 and 12, prepare a laminate in which the
foamable resin composition 2a is sandwiched between the pair of glass cloths 3, and the laminate
is prepared in the molding dies 11 and 12 And may be subjected to heat press molding as shown
below.
[0071]
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And it heat-press-molds by heating and pressurizing the metal molds 11 and 12 in which the
foamable resin composition 2a and a pair of glass cloth 3 were arrange | positioned inside. By
this heating, the thermally expandable microcapsules are thermally expanded to obtain the foam
layer 2 in a foamed state, and the pair of glass cloths 3 is adhered by the foam layer 2 to be
integrated, and vibration for a speaker The board 1 can be obtained.
[0072]
For example, a flat mold, a dome mold, an edge mold and the like can be used as the molding
molds 11 and 12, and among these, it is appropriately selected according to the shape of the
diaphragm 1 for a speaker, etc. Can be used. Further, as a molding method, known molding
methods such as compression molding, transfer molding, injection molding and the like can be
applied. Among these, for speakers having a sandwich structure from the foamable resin
composition 2a and a pair of glass cloths 3 From the viewpoint of easily obtaining the diaphragm
1, compression molding is preferably used.
[0073]
The molding conditions, that is, the molding temperature, the molding pressure, the molding
time, the mold clearance, etc. are not necessarily limited and can be set appropriately, but from
the viewpoint of appropriately foaming the foamable resin composition 2a, The molding
temperature is 150 ° C. to 200 ° C., the molding pressure is 1 MPa or more and 350 MPa or
less, the molding time is 1 minute or more and 20 minutes or less, and the mold clearance is 0.6
mm or more and 1 mm or less.
[0074]
Moreover, as a method of manufacturing the diaphragm 1 for a speaker, a continuous molding
method in which the foamable resin composition 2a and the pair of glass cloths 3 are
continuously integrated may be applied. For example, a roll laminating method or a double belt A
continuous laminating method such as a pressing method may be applied.
[0075]
FIG. 5 shows an example of the manufacturing method by the double belt press method.
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The laminating apparatus 21 used in this manufacturing method has a pair of upper and lower
rotating steel belts 22. A relatively narrow portion facing them is a foamable resin composition
2a and a pair of glass cloths 3 And a laminating unit 23 for heating and pressing to integrate
them.
[0076]
One set of steel belts 22 is configured to move from the right side to the left side in the
laminating unit 23, as indicated by arrows in the figure.
Further, while being held by the roller 25, the roller 25 is configured to be able to move
continuously in a predetermined direction while changing the direction of the roller 25.
[0077]
The clearance of the laminating portion 23, that is, the distance between the opposing surfaces of
the pair of steel belts 22 in the laminating portion 23, is the thickness of the diaphragm 1 for a
speaker to be finally obtained, specifically, the foam layer 2 Although it changes with thickness of
glass cloth 3, it is 0.1 mm or more and 2 mm or less, for example.
[0078]
The heating in the laminating section 23 may be made uniform at the whole, but it is preferable
to gradually increase the temperature sequentially from the introduction side (right side in the
figure) of the foamable resin composition 2a etc. It is preferable to set the low temperature
region and the high temperature region in order from the introduction side.
The low temperature region is, for example, 70 ° C. to 150 ° C. from the viewpoint of foaming
the foamable resin composition 2 a and bonding the pair of glass cloths 3 and smoothing the
surface of the foamable resin composition 2 a. It is preferable to do. Moreover, it is preferable to
set it as 150 degreeC-200 degreeC from a viewpoint which hardens the foamable resin
composition 2a and it integrates the whole completely.
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[0079]
With regard to such a laminating apparatus 21, a pair of glass cloths 3 is continuously
introduced from the right side in the drawing so as to be drawn into a pair of steel belts 22 in the
laminating section 23. In addition, the foamable resin composition 2a is continuously introduced
between the pair of glass cloths 3 introduced into the laminating device 21 by a coating device
(not shown) or the like.
[0080]
Then, in the case where the foamable resin composition 2a is disposed between the pair of glass
cloths 3 as described above, for example, the foamable resin composition 2a is foamed by
passing through the low temperature region in the laminating unit 23, While bonding a pair of
glass cloth 3, the surface of this foamable resin composition 2a is smoothed. Thereafter, by
passing the high temperature region further and pressurizing as necessary, for example, the
foamable resin composition 2a is cured and the whole is completely integrated, and the foamable
resin composition 2a is maximally foamed. . Thus, what the foamable resin composition 2a and a
pair of glass cloth 3 integrated can be made into the final diaphragm 1 for speakers by cut |
disconnecting in a desired shape.
[0081]
Hereinafter, the present invention will be described in detail with reference to examples.
[0082]
Example 1 First, each component was blended at a ratio as shown below, and kneading was
performed for 10 minutes at a rotation number of 60 rpm using a kneader to prepare a foamable
resin composition [1].
The injection order of each component was performed in the order as described below. In
addition, the injection | throwing-in order of each component is not necessarily limited to such
an injection | throwing-in order.
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[0083]
Resin composition [1] (1) Epoxy resin: 100 parts by mass (2) Hardening agent: 35 parts by mass
(3) Hollow spherical inorganic substance: 54 parts by mass (4) Thermally expandable
microcapsules: 4 parts by mass
[0084]
The details of each component are as follows.
Epoxy resin: JER 807 (trade name), Japan Epoxy Resins Co., Ltd. Hardener: TCG 3049 B (trade
name), Kyocera Chemical Co., Ltd. Hollow spherical inorganic substance: K-37 (trade name),
Sumitomo 3M, glass balloon Average particle size 50 μm, apparent density 0.37 g / cm 3
Thermally expandable microcapsule: (053) DU40 (trade name) manufactured by Nippon Fillite,
average particle size 15 μm, expansion start temperature 100 ° C., maximum expansion
temperature 160 ° C
[0085]
Next, after applying a mold release agent to the inner surfaces of both flat molds, AS1067 (Asahi
Kasei Electronics Co., Ltd., trade name, nominal thickness 30 μm) is disposed as a pair of glass
cloths, and the glass cloth The foamable resin composition [1] described above is introduced, and
hot press molding is performed for 30 minutes under the conditions of a temperature of 160 to
180 ° C. and a pressure of 5 MPa to manufacture a diaphragm for a speaker having a thickness
of 0.4 mm. did.
[0086]
Example 2 A diaphragm for a speaker having a thickness of 0.4 mm was produced in the same
manner as in Example 1 except that the resin composition [2] was used.
Resin composition [2] (1) Epoxy resin: 100 parts by mass (2) Hardening agent: 33 parts by mass
(3) Hollow spherical inorganic substance: 150 parts by mass
[0087]
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Example 3 A diaphragm for a speaker having a thickness of 0.4 mm was produced in the same
manner as in Example 1 except that AS2116 (trade name, nominal thickness 100 μm,
manufactured by Asahi Kasei Electronics Co., Ltd.) was used as the glass cloth.
[0088]
Comparative Example 1 A speaker diaphragm was manufactured in the same manner as in
Example 1 except that a glass epoxy prepreg TLP-551 (trade name, manufactured by Kyocera
Chemical Co., Ltd.) having a thickness of 45 μm was used instead of the glass cloth described
above. did.
[0089]
Comparative Example 2 A speaker diaphragm was prepared in the same manner as in Example 1
except that a 30 μm thick polymer film (Kapton EN (trade name), manufactured by Toray
DuPont Co., Ltd.) was used instead of the glass cloth described above. Manufactured.
[0090]
Next, the following characteristic evaluation was performed about each diaphragm for speakers
of the Example and comparative example which were mentioned above.
The results are shown in Table 1, FIGS.
[0091]
(Density) The density of each speaker diaphragm was measured in accordance with JIS K 6758.
Elastic Modulus The flexural modulus of each speaker diaphragm was measured by a thermal
analysis (DMA) method.
(Specific Elastic Modulus) From the elastic modulus and the density described above, it was
calculated by “elastic modulus / density”. (Output sound pressure frequency characteristics)
The speaker diaphragms of Examples 1 to 3 and Comparative Examples 1 and 2 are incorporated
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in the same speakers respectively, and the sound pressure frequency characteristics are acquired
using the response checker manufactured by Japan Audio Corporation. did.
[0092]
[0093]
As is apparent from Table 1, the speaker diaphragm of the embodiment manufactured by
arranging the glass cloth on both main surfaces of the foam layer and exposing the intersection
points of the warp and weft is a warp and a weft. Compared with the speaker diaphragm of the
comparative example in which the intersection is not exposed, the specific elastic modulus is
high, and the output in the high range is also high as shown in FIGS. I understand.
[0094]
As mentioned above, although the present invention was explained in detail based on the abovementioned example, the present invention is not limited to the above-mentioned example, and
various modification and change are possible unless it deviates from the category of the present
invention.
[0095]
Reference Signs List 1 diaphragm for speaker 2 foam layer 2a foamable resin composition 3
glass cloth 6 thermally expandable microcapsules 11 and 12 (after thermal expansion) molding
die 11a 12a inner surface of molding die
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