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JP2012100334

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DESCRIPTION JP2012100334
A speaker diaphragm having no anisotropy and a method of manufacturing the same. A speaker
diaphragm characterized by being formed by molding a material containing a thermoplastic
aromatic liquid crystal polyester and having no anisotropy. Further, a speaker comprising a
solution containing a thermoplastic aromatic liquid crystal polyester dissolved in a solvent to
obtain an aromatic liquid crystal polyester composition solution, the solution is cast, and the
solvent is removed from the solution. Diaphragm. A method of manufacturing a speaker
diaphragm characterized in that a material containing a thermoplastic aromatic liquid crystal
polyester is dissolved in a solvent to obtain an aromatic liquid crystal polyester composition
solution, the solution is cast, and the solvent is removed. 【Selection chart】 None
Speaker diaphragm and method of manufacturing the same
[0001]
The present invention relates to a speaker diaphragm and a method of manufacturing the same.
[0002]
Generally, in order to reproduce the original sound from which the speaker is faithful, it is
required to improve the reproduction frequency characteristic and to reduce the distortion rate.
Therefore, the diaphragm material is required to have a large specific elastic modulus (Young's
modulus / density) in order to widen the reproduction frequency band, and a large internal loss
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in order to reduce the distortion factor. Conventionally, for speaker diaphragms, metals such as
aluminum and titanium, and polymer materials such as polypropylene have been used, but
metals have large elastic modulus but small internal loss, and polymeric materials such as
polypropylene have internal loss There is a problem that the elastic modulus is small but large.
As a material having a large specific elastic modulus and a large internal loss, an aromatic
thermotropic liquid crystal polymer is attracting attention, and a speaker diaphragm using the
liquid crystal polymer is also studied. For example, Japanese Patent Publication No. 4-39279
discloses a speaker diaphragm having a liquid crystal polymer orientation formed therein by
injection molding of a material containing an aromatic liquid crystal polyester. However, in the
case of producing a speaker diaphragm by injection molding, the specific modulus of elasticity in
the longitudinal direction (extrusion and flow direction) is excellent because of anisotropy due to
the strong orientation characteristic of liquid crystal polymers. There is a problem that it is
inferior to the specific elastic modulus in the lateral direction (the direction perpendicular to the
extrusion and flow direction). In addition, since the processability is not sufficient, it has been
difficult to manufacture a large-sized diaphragm having a thin-walled shape.
[0003]
Japanese Examined Patent Publication 4-39279
[0004]
An object of the present invention is to provide a speaker diaphragm having no anisotropy and a
method of manufacturing the same.
[0005]
As a result of intensive studies to find a speaker diaphragm which does not have the abovementioned problems, the present inventors have made the speaker diaphragm having no
anisotropy not only in the longitudinal direction but also in the specific modulus in the lateral
direction. It has been found that the present invention is excellent.
[0006]
That is, the present invention provides a speaker diaphragm characterized by being formed by
molding a material containing a thermoplastic aromatic liquid crystal polyester and having no
anisotropy.
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In the present invention, a material containing a thermoplastic aromatic liquid crystalline
polyester is dissolved in a solvent to obtain an aromatic liquid crystalline polyester composition
solution, the solution is cast, and the solvent is removed from the solution. It provides a speaker
diaphragm characterized by the above.
[0007]
According to the present invention, it is possible to provide a speaker diaphragm having a high
specific elastic modulus, a large internal loss, and significantly improved sound pressure
frequency characteristics and high frequency distortion.
In addition, it is possible to provide a thin speaker diaphragm without anisotropy.
[0008]
Hereinafter, the present invention will be described in detail.
The liquid crystalline polyester used in the present invention is a polyester referred to as a
thermotropic liquid crystalline polymer, for example, (1) comprising a combination of an
aromatic dicarboxylic acid, an aromatic diol and an aromatic hydroxycarboxylic acid, (2) different
types of aromatic Which are composed of a group hydroxycarboxylic acid, (3) a combination of
an aromatic dicarboxylic acid and an aromatic diol, (4) those obtained by reacting an aromatic
hydroxycarboxylic acid with a polyester such as polyethylene terephthalate, etc. Forming an
anisotropic melt at a temperature of 400 ° C. or less. In place of these aromatic dicarboxylic
acids, aromatic diols and aromatic hydroxycarboxylic acids, ester-forming derivatives thereof
may be used.
[0009]
As ester-forming derivatives of carboxylic acid, for example, those in which the carboxyl group is
a derivative such as an acid chloride, an acid anhydride or the like that has high reaction activity
and promotes the reaction to form a polyester, the carboxyl group is And derivatives thereof
which form an ester with alcohols, ethylene glycol and the like and which form a polyester by a
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transesterification reaction. Moreover, as an ester-forming derivative of phenolic hydroxyl group,
for example, those in which the phenolic hydroxyl group forms an ester with carboxylic acids,
and which is a derivative that generates polyester by transesterification reaction can be
mentioned.
[0010]
The aromatic dicarboxylic acid, the aromatic diol and the aromatic hydroxycarboxylic acid may
be substituted with a halogen atom, a methyl group, an ethyl group, an allyl group or the like as
long as the ester formability is not inhibited.
[0011]
Although the following can be illustrated as a repeating structural unit of this liquid crystalline
polyester, It is not limited to these.
[0012]
Repeating structural units derived from aromatic hydroxycarboxylic acids:
[0013]
<img class = "EMIRef" id = "205298002-00002" />
[0014]
(Wherein, X 1 represents a halogen atom or an alkyl group.
)
[0015]
Repeating structural units derived from aromatic dicarboxylic acids:
[0016]
<img class = "EMIRef" id = "205298002-00003" />
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[0017]
(Wherein, X 2 represents a halogen atom, an alkyl group or an aryl group).
)
[0018]
Repeating structural units derived from aromatic diols:
[0019]
<img class = "EMIRef" id = "205298002-00004" />
[0020]
(Wherein, X 3 represents a halogen atom, an alkyl group or an aryl group, and X 4 represents a
hydrogen atom, a halogen atom or an alkyl group.
)
[0021]
In the above X 1 to X 4, an alkyl group is preferably an alkyl group having 1 to 10 carbon atoms,
and an aryl group is preferably an aryl group having 6 to 20 carbon atoms.
[0022]
From the viewpoint of the balance of heat resistance and mechanical properties, the aromatic
liquid crystal polyester preferably contains at least 30 mol% of the repeating unit represented by
Formula A1.
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Examples of combinations of repeating structural units include the following (a) to (f).
(A): (A1), (B2), (C3), or (A1), a mixture of (B1) and (B2), (C3).
(B): A combination of structural units in (a), with part or all of (C3) replaced with (C1).
(C): A combination of structural units in (a), with part or all of (C3) replaced with (C2).
(D): A combination of structural units in (a), with part or all of (C3) replaced with (C4).
(E): A combination of structural units in (a), in which part or all of (C3) is replaced with a mixture
of (C4) and (C5). (F): A combination of structural units in (a), in which a part of (A1) is replaced
with (A2).
[0023]
As the aromatic polyester used in the present invention, the aromatic liquid crystal polyester is
30 to 80 mol% of a repeating structural unit derived from p-hydroxybenzoic acid, hydroquinone,
resorcinol, 4,4'-dihydroxybiphenyl from the viewpoint of liquid crystal expression. 10 to 35 mol%
of a repeating structural unit derived from at least one compound selected from the group
consisting of bisphenol A and bisphenol S, derived from at least one compound selected from the
group consisting of terephthalic acid, isophthalic acid and naphthalene dicarboxylic acid It is
preferable that it consists of 10-35 mol% of repeating structural units.
[0024]
Further, as the aromatic polyester used in the present invention, from the viewpoint of heat
resistance, the aromatic liquid crystal polyester is composed of 30 to 80 mol% of repeating
structural units derived from p-hydroxybenzoic acid, hydroquinone and 4,4'-dihydroxybiphenyl
10 to 35 mol% of repeating structural units derived from at least one compound selected from
the group consisting of 10 to 35 mol% of repeating structural units derived from at least one
compound selected from the group consisting of terephthalic acid and isophthalic acid Is
preferred.
[0025]
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A publicly known method can be adopted as a method of synthesizing the liquid crystal polyester
used in the present invention.
For example, the methods described in JP-B-47-47870 and JP-B-63-3888 can be mentioned.
[0026]
The solvent used to dissolve the aromatic liquid crystal polyester of the present invention is not
particularly limited as long as it can dissolve the aromatic liquid crystal polyester, but a solvent
containing 30% by weight or more of a phenol compound represented by the following general
formula (I) However, it is preferably used because it can dissolve aromatic liquid crystalline
polyester at normal temperature or under heating.
[0027]
<img class = "EMIRef" id = "205298002-000005" />
[0028]
In addition, a solvent containing 30% by weight or more of a phenol compound represented by
the following general formula (II) is preferable, and a solvent containing 60% by weight or more
of the phenol compound is more preferable because aromatic liquid crystalline polyester can be
dissolved at relatively low temperature. Further, 100% by weight of the phenolic compound is
more preferable because it does not need to be mixed with other components.
[0029]
<img class = "EMIRef" id = "205298002-000006" />
[0030]
Here, in general formula (I), A represents a halogen atom or a trihalogenated methyl group, and i
represents an integer value of 1 to 5.
When i is 2 or more, a plurality of A may be the same as or different from each other, but are
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preferably the same.
As a halogen atom, a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom are
mentioned, and a fluorine atom and a chlorine atom are preferable.
Examples of the general formula (I) in which the halogen atom is a fluorine atom include
pentafluorophenol, tetrafluorophenol and the like.
Examples of the general formula (I) in which the halogen atom is a chlorine atom include ochlorophenol and p-chlorophenol. From the viewpoint of solubility, p-chlorophenol is preferred.
The halogen of the trihalogenated methyl group includes a fluorine atom, a chlorine atom, a
bromine atom and an iodine atom. Examples of the general formula (I) in which the halogen of
the trihalogenated methyl group is a fluorine atom include 3,5-bistrifluoromethylphenol.
[0031]
p-chlorophenol may further have a substituent, and the phenol compound represented by the
above general formula (II) is preferable from the viewpoint of price and availability. The
component to be contained in the solvent other than the phenol compound is not particularly
limited as long as it does not precipitate an aromatic liquid crystal polyester during storage of the
solution or during casting as described later, but chlorine compounds such as chloroform,
methylene chloride and tetrachloroethane And mixtures thereof are preferred in terms of price
and availability.
[0032]
The amount of the aromatic polyester added is preferably 0.5 to 100 parts by weight with
respect to 100 parts by weight of the solvent containing 30% by weight or more of the abovementioned phenol compound, and 1 to 50 parts by weight from the viewpoint of workability or
economy. Is more preferable, and 3 to 10 parts by weight is further preferable. If it is less than
0.5 parts by weight, the production efficiency tends to decrease, and if it exceeds 100 parts by
weight, dissolution tends to be difficult.
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[0033]
The aromatic liquid crystal polyester solution of the present invention is an inorganic filler such
as silica, aluminum hydroxide, calcium carbonate, glass fiber, carbon fiber, wollastonite, talc,
mica, graphite or the like, as long as the object of the present invention is not impaired. Organic
filler such as epoxy resin, crosslinked benzoguanamine resin, crosslinked acrylic polymer,
polyamide, polyester, polyphenylene sulfide, polyether ketone, polycarbonate, polyether sulfone,
polyphenyl ether and its modified products, thermoplastic resin such as polyether imide, At least
one kind of additive such as thermosetting resin such as phenol resin, epoxy resin, polyimide
resin, cyanate resin, silane coupling agent, antioxidant, ultraviolet absorber may be added.
[0034]
The speaker diaphragm of the present invention dissolves a material containing an aromatic
polyester in a solvent, filters it with a filter if necessary, and removes fine foreign substances
contained in the solution, and then, Teflon (registered trademark), metal, It can be obtained by
casting on a flat and uniform support made of glass or the like and then removing the solvent
and, if necessary, peeling off from the support substrate.
The method for casting the aromatic liquid crystalline polyester solution is not particularly
limited, and examples thereof include a roller coating method, a dip coating method, a spray
coating method, a spinner coating method, a curtain coating method, a slot coating method and a
screen printing method. The obtained film may be further subjected to a heat treatment to
increase the specific modulus, if necessary.
[0035]
Although the removal method of a solvent is not specifically limited, It is preferable to carry out
by evaporating a solvent. As a method of evaporating the solvent, methods such as heating,
reduced pressure, ventilation and the like can be mentioned. Among them, it is preferable to
evaporate the solvent by heating from the viewpoint of production efficiency and handleability,
and it is more preferable to evaporate by heating while ventilating.
[0036]
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The loudspeaker diaphragm thus obtained is characterized in that it has no orientation of the
liquid crystal polymer, ie no anisotropy. Moreover, according to the above method, a thin speaker
diaphragm can be easily obtained. Preferably, the speaker diaphragm is given a shape suitable
for the speaker diaphragm, such as a dome shape. At this time, the film thickness of the
diaphragm is preferably 5 to 100 μm, more preferably 10 to 50 μm, from the viewpoint of
processability. If necessary, metal may be further deposited on the surface of the diaphragm.
[0037]
Hereinafter, the present invention will be described by way of examples, but it goes without
saying that the present invention is not limited by the examples.
[0038]
Synthesis Example 1 141 g (1.02 mol) of p-hydroxybenzoic acid, 63.3 g of 4,4'dihydroxybiphenyl in a reactor equipped with a stirrer, torque meter, nitrogen gas inlet tube,
thermometer and reflux condenser (0.34 mol), 56.5 g (0.34 mol) of isophthalic acid and 191 g
(1.87 mol) of acetic anhydride were charged.
After the inside of the reactor was sufficiently replaced with nitrogen gas, the temperature was
raised to 150 ° C. in 15 minutes under a nitrogen gas flow, and the temperature was maintained
and reflux was performed for 3 hours. Thereafter, the temperature was raised to 320 ° C. over
170 minutes while distilling off the by-product acetic acid distilled off and the unreacted acetic
anhydride, and when the increase in torque was observed was regarded as the completion of the
reaction, and the contents were taken out. The obtained solid content was cooled to room
temperature, crushed with a coarse crusher, held at 260 ° C. under a nitrogen atmosphere for
10 hours, and subjected to a polymerization reaction in the solid phase to obtain an aromatic
liquid crystalline polyester powder.
[0039]
Example 1 1 g of the aromatic liquid crystal polyester powder obtained by Synthesis Example 1
was added to 9 g of p-chlorophenol, and as a result of heating to 120 ° C., it was confirmed that
a completely dissolved solution was obtained. This solution was cast on a glass substrate, the
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solvent was evaporated at 100 ° C. for 1 hour in a ventilated oven, and heat treatment was
further performed at 190 ° C. for 1 hour. As a result, a 30 μm thick film could be obtained. As
a result of measuring the orientation pattern with a simple molecular orientation meter (MOA5012 manufactured by Oji Scientific Instruments), the ratio of longitudinal direction (molecular
flow direction) orientation (MD) to transverse orientation (TD) is 1, and anisotropic It did not
have sex. The specific elastic modulus (E / ρ) and tan δ (internal loss) of this film test piece
were measured by the cantilever flexural vibration method. The results are shown in the table.
[0040]
Comparative Example 1 In the same manner as in Example 1, a film with a thickness of 25 μm
of an inflation-formed film produced according to the method described in Example 1 of JP-A-9286907 (direction of flow of molecules) orientation (MD) and transverse direction The specific
modulus (E / ρ) and tan δ (internal loss) of the orientation (TD) were measured. The results are
shown in the table.
[0041]
Comparative Example 2 The specific elastic modulus (E / ρ) and tan δ (internal loss) of a
commercially available polyethylene terephthalate film (S-50 manufactured by Unitika, thickness
50 μm) were measured in the same manner as in Example 1. The results are shown in the table.
[0042]
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