JP5304906B2 - Manufacturing method of speaker diaphragm - Google Patents

Description

The present invention relates to a process for producing a speaker diaphragm.

  In general, in order for a speaker to reproduce a faithful original sound, it is required to improve reproduction frequency characteristics and reduce distortion. 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 to have a large internal loss in order to reduce the distortion rate. Conventionally, metal materials such as aluminum and titanium and polymer materials such as polypropylene have been used for speaker diaphragms, but metal has a large elastic modulus but low internal loss, and polymer materials such as polypropylene do not have internal loss. There was a problem that the elastic modulus was small although it was large. Aromatic thermotropic liquid crystal polymers are attracting attention as materials having large specific elastic modulus and internal loss, and speaker diaphragms using such liquid crystal polymers are also being studied. For example, Japanese Patent Publication No. 4-39279 discloses a speaker diaphragm in which a material containing an aromatic liquid crystal polyester is injection-molded and has an orientation of a liquid crystal polymer inside. However, when producing a speaker diaphragm by injection molding, since there is anisotropy due to the strong orientation characteristic of liquid crystal polymer, the specific modulus in the longitudinal direction (extrusion / flow direction) is excellent, There was a problem that the specific modulus in the lateral direction (direction perpendicular to the extrusion / flow direction) was inferior. Further, since the workability is not sufficient, it is difficult to manufacture a thin diaphragm having a large shape.

Japanese Examined Patent Publication No. 4-39279

An object of the present invention is not longitudinally only to provide a method for manufacturing a speaker diaphragm which is excellent in the transverse direction of the specific elastic modulus.

The present inventors have made repeated sharp mind consideration, the thermoplastic aromatic liquid crystal polyester is dissolved in a solvent to obtain an aromatic liquid-crystalline polyester solution was cast the solution, removing the solvent from the solution Accordingly, not only the vertical direction only, found that the speaker diaphragm Ru excellent lateral specific modulus is obtained, and have completed the present invention.

That is, the present invention is a thermoplastic aromatic liquid crystal polyester Le dissolved in a solvent to obtain an aromatic liquid crystal polyester Le solvent solution, cast solution, and features that you remove the Solvent from the solution A method for manufacturing a speaker diaphragm is provided.

The present invention, not longitudinally only excellent in the transverse direction of the specific modulus and internal loss is large, and by extension, improved reproduction frequency characteristic, distortion factor to provide speakers oscillation rotation plate with reduced It becomes possible .

It will be described in detail with this onset Akira. The aromatic liquid crystal polyester used in the present invention is an aromatic polyester called a thermotropic liquid crystal polymer. For example, (1) a combination of aromatic dicarboxylic acid, aromatic diol and aromatic hydroxycarboxylic acid, (2 ) Composed of different kinds of aromatic hydroxycarboxylic acids, (3) composed of combinations of aromatic dicarboxylic acids and aromatic diols, and (4) those obtained by reacting aromatic hydroxycarboxylic acids with polyesters such as polyethylene terephthalate, The anisotropic melt is formed at a temperature of 400 ° C. or lower. In addition, you may use those ester-forming derivatives instead of these aromatic dicarboxylic acid, aromatic diol, and aromatic hydroxycarboxylic acid.

  Examples of ester-forming derivatives of carboxylic acids include those in which the carboxyl group has a high reaction activity such as acid chlorides and acid anhydrides, and is a derivative that promotes the reaction to form polyester, Further, there may be mentioned those formed as esters with alcohols, ethylene glycol and the like, and forming a polyester by transesterification. Examples of the ester-forming derivative of the phenolic hydroxyl group include those in which the phenolic hydroxyl group forms an ester with a carboxylic acid and forms a polyester by a transesterification reaction.

  In addition, the aromatic dicarboxylic acid, aromatic diol, and 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 forming property is not inhibited.

The repeating structural units of the aromatic liquid crystal polyester, can be mentioned as follows, but the invention is not limited thereto.

Repeating structural units derived from aromatic hydroxycarboxylic acids:

(In the formula, X ₁ represents a halogen atom or an alkyl group.)

Repeating structural units derived from aromatic dicarboxylic acids:

(In the formula, X ₂ represents a halogen atom, an alkyl group or an aryl group.)

Repeating structural units derived from aromatic diols:

(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.)

In X _{1 to} X ₄ above, the alkyl group is preferably an alkyl group having 1 to 10 carbon atoms, and the aryl group is preferably an aryl group having 6 to 20 carbon atoms.

Heat resistance, aromatic liquid crystal polyester from the balance of mechanical properties, preferably contains a repeating unit represented by A ₁ expression at least 30 mol%. Examples of the combination of repeating structural units include the following (a) to (f).
(A): (A ₁ ), (B ₂ ), (C ₃ ), or (A ₁ ), a mixture of (B ₁ ) and (B ₂ ), (C ₃ ).
(B): A combination of structural units of (a), wherein (C ₃ ) is partially or entirely replaced with (C ₁ ).
(C): A combination of structural units of (a), wherein (C ₃ ) is partially or entirely replaced with (C ₂ ).
(D): A combination of structural units of (a), wherein (C ₃ ) is partially or entirely replaced with (C ₄ ).
(E) in what combination of structural units of :( a), replaced with the mixture of (C ₃₎ of some or all the _{(C 4) (C 5)} .
(F): A combination of structural units of (a), wherein (A ₁ ) is partially replaced with (A ₂ ).

As the aromatic liquid crystal polyester used in the present invention, 30 to 80 mol% of repeating structural units derived from p -hydroxybenzoic acid, hydroquinone, resorcinol, 4,4′-dihydroxybiphenyl, bisphenol A and bisphenol are used in terms of liquid crystallinity. 10 to 35 mol% of repeating structural units derived from at least one compound selected from the group consisting of S, and 10 to 10 repeating structural units derived from at least one compound selected from the group consisting of terephthalic acid, isophthalic acid and naphthalenedicarboxylic acid those composed of ~35mol% is preferred.

The aromatic liquid crystal polyester used in the present invention is selected from the group consisting of 30 to 80 mol% of repeating structural units derived from p -hydroxybenzoic acid, hydroquinone and 4,4′-dihydroxybiphenyl from the viewpoint of heat resistance. Those having 10 to 35 mol% of repeating structural units derived from at least one compound and 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 are preferred.

As a method for synthesizing the aromatic liquid crystal polyester used in the present invention, a known method can be employed. For example, methods described in JP-B-47-47870 and JP-B-63-3888 can be mentioned.

  The solvent used for dissolving 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 it is a solvent containing 30% by weight or more of the phenol compound represented by the following general formula (I). However, it is preferably used because the aromatic liquid crystalline polyester can be dissolved at room temperature or under heating.

  Further, since the aromatic liquid crystal polyester can be dissolved at a relatively low temperature, a solvent containing 30% by weight or more of the 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. More preferably, the phenol compound is substantially 100% by weight because it is not necessary to mix with other components.

  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 or different from each other, but are preferably the same. Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom, 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 and tetrafluorophenol. Examples of the general formula (I) in which the halogen atom is a chlorine atom include o-chlorophenol and p-chlorophenol, and p-chlorophenol is preferred from the viewpoint of solubility. Examples of the halogen of the trihalogenated methyl group include 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.

  p-Chlorophenol may further have a substituent, and a phenol compound represented by the above general formula (II) is preferable from the viewpoints of price and availability. The component contained in the solvent other than the phenolic compound is not particularly limited as long as it does not cause the aromatic liquid crystal polyester to precipitate during storage of the solution or casting as described later, but chlorine compounds such as chloroform, methylene chloride, tetrachloroethane, etc. Are preferable from the viewpoint of price and availability.

The addition amount of the aromatic liquid crystal polyester 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 above phenol compound, and 1 to 50 parts by weight from the viewpoint of workability or economy. Part is more preferable, and 3 to 10 parts by weight is still more preferable. If the amount 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.

  In the aromatic liquid crystal polyester solution of the present invention, inorganic fillers such as silica, aluminum hydroxide, calcium carbonate, glass fiber, carbon fiber, wollastonite, talc, mica, and graphite are cured as long as the object of the present invention is not impaired. Organic fillers such as epoxy resins, crosslinked benzoguanamine resins, crosslinked acrylic polymers, thermoplastic resins such as polyamide, polyester, polyphenylene sulfide, polyether ketone, polycarbonate, polyether sulfone, polyphenyl ether and modified products thereof, polyether imide, etc. You may add at least 1 type of various additives, such as thermosetting resins, such as a phenol resin, an epoxy resin, a polyimide resin, and cyanate resin, a silane coupling agent, antioxidant, and an ultraviolet absorber.

Speaker diaphragm of the present invention, the aromatic liquid crystal polyester Le dissolved in a solvent, filtered by a filter if necessary, after removal of the fine foreign matter contained in the solution, Teflon, metal, glass It can be obtained by casting on a flat and uniform support made of, etc., removing the solvent, and then peeling off from the support substrate as necessary. The method for casting the aromatic liquid crystal 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 elastic modulus, if necessary.

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 agent, heating, vacuum, and a method such as ventilation. Among these, from the viewpoint of production efficiency and handling, it is preferable to evaporate the solvent by heating, and it is more preferable to evaporate by heating with ventilation.

  The speaker diaphragm thus obtained is characterized by having no orientation of the liquid crystal polymer, that is, having no anisotropy. Moreover, according to the said method, a thin speaker diaphragm can be obtained easily. The speaker diaphragm is preferably provided with a shape suitable as a 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 workability. Moreover, you may perform the process of vapor-depositing a metal further on the surface of a diaphragm as needed.

  EXAMPLES Hereinafter, although an Example demonstrates this invention, it cannot be overemphasized that this invention is not what is limited by an Example.

Synthesis example 1
In a reactor equipped with a stirrer, a torque meter, a nitrogen gas inlet tube, a thermometer and a reflux condenser, 141 g (1.02 mol) of p-hydroxybenzoic acid and 63.3 g (0. 3 mol) of 4,4′-dihydroxybiphenyl were added. 34 mol), 56.5 g (0.34 mol) of isophthalic acid, and 191 g (1.87 mol) of acetic anhydride. After sufficiently replacing the inside of the reactor with nitrogen gas, the temperature was raised to 150 ° C. over 15 minutes under a nitrogen gas stream, and the temperature was maintained and refluxed for 3 hours. Thereafter, the temperature was raised to 320 ° C. over 170 minutes while distilling off the by-product acetic acid and unreacted acetic anhydride, and the time when an increase in torque was observed was regarded as the completion of the reaction, and the contents were taken out. The obtained solid was cooled to room temperature, pulverized with a coarse pulverizer, held at 260 ° C. for 10 hours in a nitrogen atmosphere, and polymerized in a solid layer to obtain an aromatic liquid crystal polyester powder.

Example 1
As a result of adding 1 g of the aromatic liquid crystal polyester powder obtained in Synthesis Example 1 to 9 g of p-chlorophenol and heating to 120 ° C., it was confirmed that a completely dissolved and transparent solution was obtained. The solution was cast on a glass substrate, after evaporation of the 1 hour Solvent at 100 ° C. in a ventilated oven, another hour heat treated results in 190 ° C., it was possible to obtain a film having a thickness of 30 [mu] m. The simple molecular orientation meter (Oji measurement instrument manufactured by MOA-5012), a result of measuring the orientation pattern, the ratio of the orientation in the longitudinal direction (the flow direction of molecules) orientation and horizontal Direction of (MD) (TD) is 1 It did not have anisotropy. About this film test piece, the specific elastic modulus (E / ρ) and tan δ (internal loss) were measured by the cantilever bending vibration method. The results are shown in the table.

Comparative Example 1
As in Example 1, the vertical direction (the flow direction of molecules) of an inflation molding film 25μm prepared according to the method described in Example 1 of JP-A-9-286907 discloses (MD) sideways direction and (TD) Specific elastic modulus (E / ρ) and tan δ (internal loss) were measured.
The results are shown in the table.

Comparative Example 2
The specific elastic modulus (E / ρ) and tan δ (internal loss) of a commercially available polyethylene terephthalate film (Unitika S-50 thickness 50 μm) were measured in the same manner as in Example 1. The results are shown in the table.

Claims (4)

The thermoplastic aromatic liquid crystalline polyester Le dissolved in a solvent to obtain an aromatic liquid-crystalline polyester solution was cast the solution, a manufacturing method of a speaker diaphragm and removing the solvent.   The aromatic liquid crystalline polyester is at least one compound selected from the group consisting of 30 to 80 mol% of repeating structural units derived from p-hydroxybenzoic acid, hydroquinone, resorcinol, 4,4′-dihydroxybiphenyl, bisphenol A and bisphenol S. 2. The speaker vibration according to claim 1, comprising 10 to 35 mol% of repeating structural units derived from 1 to 10 and 35 mol% of repeating structural units derived from at least one compound selected from the group consisting of terephthalic acid, isophthalic acid and naphthalenedicarboxylic acid. A manufacturing method of a board. The solvent is represented by the following general formula (I)

(In the formula, A represents a halogen atom or a trihalogenated methyl group, i represents an integer value of 1 to 5. When i is 2 or more, a plurality of A may be the same or different from each other. )
The method for producing a speaker diaphragm according to claim 1, wherein the solvent contains a phenol compound represented by the formula: The solvent is represented by the following general formula (II)

(In the formula, A ′ represents a hydrogen atom, a halogen atom or a trihalogenated methyl group, i represents an integer value of 1 to 5. When i is 2 or more, a plurality of A's may be the same or different. May be)
The method for producing a speaker diaphragm according to claim 1, wherein the solvent contains a phenol compound represented by the formula: