Acoustic diaphragm, its manufacturing method, and acoustic device

Abstract

Provided is an acoustic diaphragm having the characteristics required for a vibration part and an edge part. The acoustic diaphragm comprises a vibration part 11 and an edge part 12 located at the outer periphery of the vibration part, both of which are formed from a thermoplastic liquid crystal polymer of the same composition, and the modulus of elasticity Ｅｄ of the vibration part 11 and the modulus of elasticity E ｅ of the edge part 12 as measured by the nanoindentation technique satisfy the relationship of Ｅｄ＞Ｅｅ. For example, the ratio Ｅｄ / Ｅｅ of the modulus of elasticity Ｅｄ of the vibration part 11 to the modulus of elasticity Ｅｅ of the edge part 12 may be 1.05 to 5.0.

Description

Related Applications

[0001] This application claims priority to Japanese Patent Application Nos. 2019-206760 and 2020-88753, filed on November 15, 2019 and May 21, 2020, respectively, the entire contents of which are incorporated herein by reference. [Technical field]

[0002] The present invention relates to an acoustic diaphragm made of a thermoplastic polymer (hereinafter referred to as a thermoplastic liquid crystal polymer) capable of forming an optically anisotropic molten phase, a method for manufacturing the same, and an acoustic device using the acoustic diaphragm. [Background technology]

[0003] In recent years, audio sources called "Hi-Res Audio", "Hi-Res Sound Sources" or simply "Hi-Res" have started to become popular, which contain a much larger amount of information than conventional sources. Hi-Res Sound Sources refer to music data with a sampling frequency and quantization bit rate of 48 kHz or 96 kHz and 24 bits or higher, which exceeds the sampling frequency and quantization bit rate (44.1 kHz and 16 bits) of conventional music CDs. As Hi-Res Sound Sources become more popular, the demands on the acoustic diaphragms used in speakers, headphones, etc. are increasing more than ever before.

[0004] An acoustic diaphragm generally consists of a vibration part and an edge part, each of which has a different role. The vibration part of the acoustic diaphragm has a high propagation velocity (E / ρ) for frequency characteristics reasons. 1 / 2) and a moderate internal loss that indicates the degree of vibration attenuation, so a material that is light (low density ρ), has a high elastic modulus E, and has a large internal loss is required. The edge part of the acoustic diaphragm is provided on the outer periphery of the vibrating part, and it is necessary to support the outer periphery of the vibrating part and hold it in the correct position, as well as to be flexible and move freely following the movement of the vibrating part without interfering with it, and to suppress divided vibrations, so a material that is relatively flexible and has a large internal loss is required. In other words, the vibrating part requires a material with a high elastic modulus, while the edge part requires a material with a relatively low elastic modulus, so different characteristics are required for each.

[0005] For this reason, conventionally, an acoustic diaphragm has been proposed in which the vibrating portion and the edge portion are separately manufactured so as to have the required characteristics, and then the portions are bonded together with an adhesive or the like.

[0006] For example, Patent Document 1 (International Publication No. 2017 / 130972) discloses a diaphragm edge material for electroacoustic transducers, characterized in that it contains, as a main component, a polyamide resin (A) composed of a dicarboxylic acid (a-1) mainly composed of terephthalic acid and a diamine component (a-2) mainly composed of an aliphatic diamine, and describes a form in which the edge material is attached around a highly elastic body attached to a voice coil.

[0007] Furthermore, Patent Document 2 (JP Patent Publication 6-153292 A) discloses a speaker edge material made by impregnating or coating a binder-free cotton nonwoven fabric with a molding resin, and describes a free edge cone for speakers in which the edge material is bonded to the outer periphery of a speaker diaphragm.

[0008] Moreover, Patent Document 3 (JP Patent Publication 2005-168050A) discloses a method for manufacturing a speaker diaphragm, which includes a step of press-molding a single wooden sheet into a substantial trumpet shape. [Prior art documents] [Patent documents]

[0009] [Patent Document 1] International Publication No. 2017 / 130972 [Patent Document 2] Japanese Patent Application Publication No. 6-153292 [Patent Document 3] JP 2005-168050 A Summary of the Invention [Problem to be solved by the invention]

[0010] However, when different materials are used for the vibration part and the edge part as in Patent Documents 1 to 3, they need to be bonded using an adhesive, so the joint required for bonding the different materials cannot achieve the intended performance of the vibration plate, and the performance of the vibration part and the edge part as a whole may differ from the design value. In addition, the presence of the adhesive makes the vibration plate thicker at the joint, so if it is necessary to make the sheet as thin as possible, it is difficult to achieve the desired thickness. The increase in thickness leads to a decrease in acoustic characteristics due to the increased rigidity of the edge part and the increased mass of the vibration plate.

[0011] Furthermore, when an adhesive is used, the adhesive has poor heat resistance. For example, in the case of an acoustic diaphragm for use in a vehicle, the adhesive portion has insufficient heat resistance because the acoustic diaphragm is exposed to high temperatures for a long period of time.

[0012] Therefore, an object of the present invention is to provide an acoustic diaphragm and a manufacturing method thereof which simultaneously possess the characteristics required for the vibrating portion and the edge portion, even though the vibrating portion and the edge portion are made of the same material.

[0013] Another object of the present invention is to provide an acoustic device equipped with such an acoustic diaphragm. [Means for solving the problem]

[0014] The inventors of the present invention have conducted intensive research to achieve the above object, and firstly, they focused on thermoplastic liquid crystal polymer, which is a material with high elastic modulus and high internal loss, and found that the film molded from it has high elastic modulus and is suitable as a material for an acoustic diaphragm, and further, that the elastic modulus of the thermoplastic liquid crystal polymer film can be changed by heating at a specific temperature. On the other hand, they found that the local elastic modulus can be measured accurately only by the nanoindentation method, and found that by heating the part corresponding to the edge at a specific temperature, the elastic modulus of the edge part can be made smaller than that of the vibration part, even though they are made of the same material, and thus completed the present invention.

[0015] That is, the present invention can be configured in the following manner. [Aspect 1] An acoustic diaphragm in which the vibration part and the edge part located on the outer periphery of the vibration part are made of a thermoplastic liquid crystal polymer of the same composition, and the elastic modulus E of the vibration part measured by the nanoindentation method is d and the elastic modulus of the edge part E e E d >E e An acoustic diaphragm that satisfies the above relationship. [Aspect 2] The acoustic diaphragm according to embodiment 1, wherein the elastic modulus E of the vibration part is d and the elastic modulus of the edge E e Ratio of E d / E e is 1.05 to 5.0 (preferably 1.1 to 4.0, more preferably 1.2 to 3.0). [Aspect 3] The acoustic diaphragm according to embodiment 1 or 2, wherein the elastic modulus E d The acoustic diaphragm has a compressive strength of 6.0 to 15.0 GPa (preferably 6.5 to 14.0 GPa, and more preferably 7.0 to 13.0 GPa). Aspect 4 The acoustic diaphragm according to any one of aspects 1 to 3, wherein the elastic modulus E eThe acoustic diaphragm has a compressive strength of 4.5 to 12.0 GPa (preferably 5.0 to 12.0 GPa, more preferably 5.5 to 11.0 GPa, and even more preferably 6.0 to 10.0 GPa). Aspect 5 The acoustic diaphragm according to any one of aspects 1 to 4, wherein the internal loss tan δ of the vibration portion and the edge portion is both within a range of 0.03 to 0.08 (preferably 0.04 to 0.08, more preferably 0.05 to 0.08). Aspect 6 The acoustic diaphragm according to any one of aspects 1 to 5, Vibration and edge parts An acoustic diaphragm having a thickness difference of 10 μm or less (preferably 5 μm or less, more preferably 3 μm or less). Aspect 7 A method for manufacturing an acoustic diaphragm in which a vibration part and an edge part are formed using a thermoplastic liquid crystal polymer film as a raw material, The method for producing an acoustic diaphragm according to any one of aspects 1 to 6, comprising a step of heat-treating a portion that forms an edge portion of a thermoplastic liquid crystal polymer film, or an edge portion of a thermoplastic liquid crystal polymer molded body that has been shaped by molding a thermoplastic liquid crystal polymer film. Aspect 8 In the method according to aspect 7, the heating temperature of the heat treatment is from (Tm-30) to (Tm+30)°C (preferably from (Tm-25) to (Tm+20)°C, and more preferably from (Tm-20) to (Tm+10)°C). (where Tm is the melting point of the thermoplastic liquid crystal polymer film) This is a method for manufacturing an acoustic diaphragm. Aspect 9 A method for producing an acoustic diaphragm according to claim 7, wherein the heat treatment is an ultrasonic treatment. Aspect 10 A method for producing an acoustic diaphragm according to any one of aspects 7 to 9, wherein the SOR of the thermoplastic liquid crystal polymer film before the heat treatment step is 0.80 to 1.30 (preferably 0.85 to 1.25, and more preferably 0.90 to 1.20). Aspect 11 An acoustic device comprising the acoustic diaphragm according to any one of the first to sixth aspects. Aspect 12 12. The audio device according to claim 11, wherein the audio device is a speaker, a headphone, or an earphone.

[0016] It should be noted that any combination of at least two elements disclosed in the claims and / or the specification and / or the drawings is included in the present invention. In particular, any combination of two or more of the claims described in the claims is included in the present invention. Effect of the Invention

[0017] According to the present invention, an acoustic diaphragm can be obtained which simultaneously has the characteristics required for the vibrating portion and the edge portion, even though the vibrating portion and the edge portion are made of the same material. [Brief description of the drawings]

[0018] The present invention will be more clearly understood from the following description of preferred embodiments with reference to the accompanying drawings. The drawings are not necessarily drawn to scale, and are exaggerated to illustrate the principles of the present invention. The embodiments and drawings are merely for illustration and description, and should not be used to define the scope of the present invention, which is defined by the appended claims. In the accompanying drawings, the same part numbers in multiple drawings indicate the same parts. [Figure 1] 1 is a schematic exploded perspective view illustrating a main portion of an earphone-type acoustic device according to an embodiment of the present invention; [Diagram 2] 2 is a schematic plan view showing an acoustic diaphragm of the acoustic device of FIG. 1. [Diagram 3] 3 is a schematic cross-sectional view showing the AA section of the acoustic diaphragm of FIG. 2. [Figure 4] FIG. 2 is a conceptual diagram showing an ultrasonic heating device for ultrasonically heating the acoustic diaphragm. [Diagram 5] FIG. 2 is a diagram partially showing the shape of the tip of the horn of the ultrasonic heating device. [Figure 6] FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0019] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. However, the present invention is not limited to the illustrated embodiment.

[0020] 1 shows a schematic exploded perspective view for explaining the main parts inside the housing of an earphone-type acoustic device according to one embodiment of the present invention. The acoustic device has at least an acoustic diaphragm 10, a pole piece 13, a voice coil 14, and a magnetic body 15. Although not shown, in addition to these main parts, the acoustic device may be appropriately provided with a housing, ear pads, an acoustic resistor, a protector, etc. Furthermore, if the desired magnetic field can be formed by the magnetic body alone, the pole piece may be omitted.

[0021] In the main part of the acoustic device shown in Figure 1, an acoustic diaphragm 10 has an F surface as the surface on the ear side and an R surface as the surface opposite the ear, and a pole piece 13, a voice coil 14, and a magnetic body 15 are arranged on the R surface side.

[0022] The magnetic body 15 generates a magnetic flux and forms a magnetic field inside the acoustic device through the pole piece 13. The voice coil 14 is arranged in a cylindrical shape surrounding the magnetic body 15, and one end of the voice coil 14 is joined to the R surface side of the acoustic diaphragm 10. The voice coil 14 may be arranged as a voice coil bobbin.

[0023] Since the voice coil 14 is connected to an electrode (not shown), a current flows from the electrode to the voice coil 14 in response to an input audio signal. When a current flows through the voice coil 14, the voice coil 14 receives a force from a magnetic field in response to the magnitude of the current. As a result, the voice coil 14 vibrates, and the vibration is transmitted to the acoustic diaphragm 10 to which the voice coil 14 is joined. This causes the acoustic diaphragm 10 to vibrate in conjunction with the vibration from the voice coil 14. When the acoustic diaphragm 10 vibrates, the vibration is transmitted into the air, generating a sound pressure in response to the input audio signal.

[0024] Fig. 2 shows a plan view of the acoustic diaphragm 10 of Fig. 1. The acoustic diaphragm 10 is a dome-shaped diaphragm composed of a dome-shaped vibrating part 11 and an edge part 12. With the part where the voice coil 14 contacts as the boundary, the vibrating part 11 is formed on the central side, and the edge part 12 is formed on the peripheral side.

[0025] In Fig. 2, a plurality of grooves 16 are formed in the edge portion 12, and by providing such grooves 16, it is possible to disperse and release distortion in the circumferential direction, thereby making it possible to suppress resonance of the acoustic diaphragm. In this way, it is possible to impart various characteristics to the acoustic diaphragm depending on the shape of the edge portion, but the shape is not particularly limited, and may have various edge shapes such as a roll edge, a corrugated edge, a gathered edge, a tangential edge, etc.

[0026] Fig. 3 shows a cross-sectional view taken along line AA of the acoustic diaphragm 10 shown in Fig. 2. The vibration part 11 and the edge part 12 are integrally formed, and each has a gently protruding shape facing the direction in which sound pressure is generated (or the F surface).

[0027] The acoustic diaphragm of the present invention is not particularly limited in shape as long as it can achieve the effects of the present invention, and may have various shapes, such as a dome shape, a cone shape, a ribbon shape, a flat shape, etc. In addition, the shape of the outer periphery or the rim of the vibrating part may have various shapes such as a circle, an ellipse, a polygonal shape, or a shape composed of a combination of two or more straight lines and curves (for example, a shape in which curved parts are provided at each of the four corners of a rectangle).

[0028] (Thermoplastic Liquid Crystal Polymer) The acoustic diaphragm of the present invention has a vibrating part and an edge part located on the outer periphery of the vibrating part each made of a thermoplastic liquid crystal polymer of the same composition, and has high stress and excellent environmental resistance properties such as heat resistance, cold resistance, etc. In a preferred embodiment of the present invention, the acoustic diaphragm can be integrated with the vibrating part and the edge part without using an adhesive, making a joint unnecessary and eliminating the deterioration of properties at the joint caused by the adhesive.

[0029] The acoustic diaphragm of the present invention is made of a thermoplastic liquid crystal polymer. The thermoplastic liquid crystal polymer is made of a liquid crystal polymer that can be melt molded (or a polymer that can form an optically anisotropic melt phase), and as long as it is a liquid crystal polymer that can be melt molded, its chemical composition is not particularly limited, but for example, it can be a thermoplastic liquid crystal polyester, or a thermoplastic liquid crystal polyester amide in which an amide bond is introduced therein.

[0030] The thermoplastic liquid crystal polymer may be a polymer in which an imide bond, a carbonate bond, a carbodiimide bond, an isocyanate-derived bond such as an isocyanurate bond, or the like is further introduced into an aromatic polyester or an aromatic polyester amide.

[0031] Specific examples of the thermoplastic liquid crystal polymer used in the present invention include known thermoplastic liquid crystal polyesters and thermoplastic liquid crystal polyesteramides derived from the compounds classified into (1) to (4) below and their derivatives. However, it goes without saying that there is an appropriate range for the combination of various raw material compounds in order to form a polymer capable of forming an optically anisotropic molten phase.

[0032] (1) Aromatic or aliphatic diols (see Table 1 for representative examples) [Table 1]

[0033] (2) Aromatic or aliphatic dicarboxylic acids (see Table 2 for representative examples) [Table 2]

[0034] (3) Aromatic hydroxycarboxylic acids (see Table 3 for representative examples) [Table 3]

[0035] (4) Aromatic diamines, aromatic hydroxyamines, or aromatic aminocarboxylic acids (see Table 4 for representative examples) [Table 4]

[0036] Representative examples of liquid crystal polymers obtained from these raw material compounds include copolymers having the structural units shown in Tables 5 and 6.

[0037] [Table 5] [Table 6]

[0038] Among these copolymers, polymers containing at least p-hydroxybenzoic acid and / or 6-hydroxy-2-naphthoic acid as repeating units are preferred, and in particular, (i) a copolymer containing repeating units of p-hydroxybenzoic acid and 6-hydroxy-2-naphthoic acid, or (ii) a copolymer containing repeating units of at least one aromatic hydroxycarboxylic acid selected from the group consisting of p-hydroxybenzoic acid and 6-hydroxy-2-naphthoic acid, at least one aromatic diol and / or aromatic hydroxyamine, and at least one aromatic dicarboxylic acid are preferred.

[0039] For example, in the case of polymer (i), when the thermoplastic liquid crystal polymer contains at least repeating units of p-hydroxybenzoic acid and 6-hydroxy-2-naphthoic acid, the molar ratio (A) / (B) of the p-hydroxybenzoic acid in the repeating unit (A) to the 6-hydroxy-2-naphthoic acid in the repeating unit (B) in the thermoplastic liquid crystal polymer is preferably about (A) / (B)=10 / 90 to 90 / 10, more preferably about (A) / (B)=15 / 85 to 85 / 15, and even more preferably about (A) / (B)=20 / 80 to 80 / 20.

[0040] In the case of the polymer (ii), at least one aromatic hydroxycarboxylic acid (C) selected from the group consisting of p-hydroxybenzoic acid and 6-hydroxy-2-naphthoic acid, at least one aromatic diol (D) selected from the group consisting of 4,4'-dihydroxybiphenyl, hydroquinone, phenylhydroquinone, and 4,4'-dihydroxydiphenyl ether, and at least one aromatic dicarbohydrate (E) selected from the group consisting of terephthalic acid, isophthalic acid, and 2,6-naphthalenedicarboxylic acid are mixed. The molar ratio of each repeating unit of the aromatic hydroxycarboxylic acid (C): the aromatic diol (D): the aromatic dicarboxylic acid (E) in the thermoplastic liquid crystal polymer may be about (30-80): (35-10): (35-10), more preferably about (C): (D): (E) = (35-75): (32.5-12.5): (32.5-12.5), and even more preferably about (C): (D): (E) = (40-70): (30-15): (30-15).

[0041] The molar ratio of repeating units derived from 6-hydroxy-2-naphthoic acid in the aromatic hydroxycarboxylic acid (C) may be, for example, 85 mol% or more, preferably 90 mol% or more, more preferably 95 mol% or more. The molar ratio of repeating units derived from 2,6-naphthalenedicarboxylic acid in the aromatic dicarboxylic acid (E) may be, for example, 85 mol% or more, preferably 90 mol% or more, more preferably 95 mol% or more.

[0042] The aromatic diol (D) may be repeating units (D1) and (D2) derived from two different aromatic diols selected from the group consisting of hydroquinone, 4,4'-dihydroxybiphenyl, phenylhydroquinone, and 4,4'-dihydroxydiphenyl ether. In this case, the molar ratio of the two aromatic diols (D1) / (D2) may be 23 / 77 to 77 / 23, more preferably 25 / 75 to 75 / 25, and even more preferably 30 / 70 to 70 / 30.

[0043] The molar ratio of the repeating structural units derived from the aromatic diol to the repeating structural units derived from the aromatic dicarboxylic acid is preferably (D) / (E)=95 / 100 to 100 / 95. If it is outside this range, the degree of polymerization does not increase and the mechanical strength tends to decrease.

[0044] The ability to form an optically anisotropic molten phase in the present invention can be confirmed, for example, by placing a sample on a hot stage, heating it in a nitrogen atmosphere, and observing the light transmitted through the sample.

[0045] The preferred thermoplastic liquid crystal polymer has a melting point (hereinafter referred to as Tm0) in the range of, for example, 200 to 360 ° C, preferably in the range of 240 to 350 ° C, and more preferably in the range of 260 to 330 ° C. The melting point of the thermoplastic liquid crystal polymer can be obtained by observing the thermal behavior of the thermoplastic liquid crystal polymer sample using a differential scanning calorimeter. That is, the thermoplastic liquid crystal polymer sample is heated from room temperature (for example, 25 ° C) at a rate of 10 ° C / min to completely melt, and then the melt is cooled to 50 ° C at a rate of 10 ° C / min, and the position of the endothermic peak that appears after heating again at a rate of 10 ° C / min may be recorded as the melting point of the thermoplastic liquid crystal polymer sample.

[0046] Furthermore, from the viewpoint of melt moldability, the thermoplastic liquid crystal polymer may have, for example, a melt viscosity of 30 to 120 Pa·s at a shear rate of 1000 / s at (Tm0+20)°C, and preferably a melt viscosity of 50 to 100 Pa·s.

[0047] The thermoplastic liquid crystal polymer may be added with thermoplastic polymers such as polyethylene terephthalate, modified polyethylene terephthalate, polyolefin, polycarbonate, polyarylate, polyamide, polyphenylene sulfide, polyether ether ketone, fluororesin, etc., reinforcing fibers such as carbon fiber, glass fiber, aramid fiber, mica, graphite, whisker, etc., various additives, etc., within the range that does not impair the effects of the present invention. Note that, in the acoustic diaphragm of the present invention, from the viewpoint of suppressing the decrease in internal loss, it may be composed of a thermoplastic liquid crystal polymer molded body that does not contain reinforcing fibers.

[0048] [Method of manufacturing acoustic diaphragms] The method for producing an acoustic diaphragm of the present invention is a method for producing an acoustic diaphragm in which a vibration part and an edge part located on the outer periphery of the vibration part are formed using a thermoplastic liquid crystal polymer film as a raw material, and may at least include a step of heat-treating a part that forms the edge part of the thermoplastic liquid crystal polymer film, or an edge part of a thermoplastic liquid crystal polymer molded body shaped by molding the thermoplastic liquid crystal polymer film, at (Tm-30) to (Tm+30)°C.

[0049] (Thermoplastic liquid crystal polymer film) The method for producing an acoustic diaphragm of the present invention may include a step of preparing a thermoplastic liquid crystal polymer film. The thermoplastic liquid crystal polymer film is obtained, for example, by extrusion molding a melt-kneaded product of the thermoplastic liquid crystal polymer. Any method can be used as the extrusion molding method, but the well-known T-die method, inflation method, etc. are industrially advantageous. In particular, in the inflation method, stress is applied not only in the mechanical axis direction (hereinafter abbreviated as MD direction) of the thermoplastic liquid crystal polymer film, but also in the direction perpendicular thereto (hereinafter abbreviated as TD direction), and the film can be uniformly stretched in the MD direction and the TD direction, so that a thermoplastic liquid crystal polymer film with controlled molecular orientation in the MD direction and the TD direction can be obtained. Therefore, the thermoplastic liquid crystal polymer film produced by the inflation method is preferable from the viewpoint of uniformity of physical properties.

[0050] For example, in extrusion molding using the T-die method, the molten sheet extruded from the T-die may be stretched not only in the MD direction of the thermoplastic liquid crystal polymer film, but also in both the TD direction and the MD direction simultaneously to form a film, or the molten sheet extruded from the T-die may be stretched first in the MD direction and then in the TD direction to form a film.

[0051] In addition, in extrusion molding by the inflation method, a cylindrical sheet melt-extruded from a ring die may be stretched at a predetermined draw ratio (corresponding to the stretch ratio in the MD direction) and blow ratio (corresponding to the stretch ratio in the TD direction) to form a film.

[0052] The stretch ratio in such extrusion molding, as a stretch ratio (or draw ratio) in the MD direction, may be, for example, about 1.0 to 10, preferably about 1.2 to 7, and more preferably about 1.3 to 7. Also, the stretch ratio (or blow ratio) in the TD direction may be, for example, about 1.5 to 20, preferably about 2 to 15, and more preferably about 2.5 to 14.

[0053] The thermoplastic liquid crystal polymer film may be isotropically oriented in the plane direction from the viewpoint of making the vibration characteristics uniform. Specifically, the molecular orientation ratio SOR of the thermoplastic liquid crystal polymer film may be 0.80 to 1.30, preferably about 0.85 to 1.25, and more preferably about 0.90 to 1.20. Here, the molecular orientation ratio SOR (Segment Orientation Ratio) refers to an index that gives the degree of molecular orientation for the segments that constitute the molecule, and is a value that takes into account the thickness of the object. The molecular orientation ratio SOR is calculated as follows.

[0054] First, in a known microwave molecular orientation measuring device, a thermoplastic liquid crystal polymer film is inserted into a microwave resonant waveguide so that the film surface is perpendicular to the direction of microwave propagation, and the electric field strength of the microwaves transmitted through the film (microwave transmission strength) is measured. Then, based on this measured value, the m value (called the refractive index) is calculated using the following formula: m = (Zo / △z)X [1-νmax / νo] where Zo is the equipment constant, △z is the average thickness of the object, νmax is the frequency that gives the maximum microwave transmission intensity when the microwave frequency is changed, and νo is the frequency that gives the maximum microwave transmission intensity when the average thickness is zero (i.e., when there is no object). Next, the m value when the rotation angle of the object with respect to the microwave vibration direction is 0°, that is, when the microwave vibration direction coincides with the direction in which the object's molecules are most oriented and which gives the minimum microwave transmission intensity, is called m0, and the m value when the rotation angle is 90° is called m 90 The molecular orientation ratio SOR is m0 / m 90 It is calculated as follows.

[0055] (Thermoplastic liquid crystal polymer molding) The method for producing an acoustic diaphragm of the present invention may include a forming step of forming a thermoplastic liquid crystal polymer molded body by forming a thermoplastic liquid crystal polymer film into a desired shape of an acoustic diaphragm. The formed thermoplastic liquid crystal polymer film may be called a molded body or a thermoplastic liquid crystal polymer molded body.

[0056] Examples of the molding method include various thermoforming methods such as pressure forming, vacuum forming, and press forming. For example, a desired shape may be imparted using a mold by pressure forming or vacuum forming to form the shape required for the acoustic diaphragm. The pressure forming method may be a method in which a film is softened and then pressed against a mold by applying pressure to the film using air pressure or the like to form the film. The vacuum forming method may be a method in which a film is softened and then drawn into a mold by creating a vacuum in the gap between the mold and the film to form the film. The press forming method may be a method in which a film is sandwiched between a pair of upper and lower molds and the film is softened by heating between the molds to form the film.

[0057] The heating temperature in the molding process may be (Tm-120) to (Tm+10)° C., where Tm is the melting point of the thermoplastic liquid crystal polymer film. The heating temperature in the molding process may be preferably (Tm-110) to (Tm+10)° C., more preferably (Tm-100) to (Tm+10)° C. The melting point Tm of the thermoplastic liquid crystal polymer film indicates the position of an endothermic peak that appears when a predetermined size is sampled from the thermoplastic liquid crystal polymer molded product using a differential scanning calorimeter, placed in a sample container, and heated from room temperature to 400° C. at a rate of 10° C. / min.

[0058] For example, in the pressure molding method, the pressure applied to the thermoplastic liquid crystal polymer film can be adjusted by the thickness of the thermoplastic liquid crystal polymer film, the heating temperature, etc., and may be, for example, 1 MPa to 10 MPa, preferably 1 MPa to 8 MPa, and more preferably 1 MPa to 4 MPa.

[0059] For example, in the vacuum molding method, the degree of vacuum can be adjusted by the thickness of the thermoplastic liquid crystal polymer film, the heating temperature, etc., and may be, for example, 200 to 700 mmHg, preferably 250 to 600 mmHg, and more preferably 300 to 500 mmHg.

[0060] As one embodiment of the present invention, a method for manufacturing an acoustic diaphragm in which a vibrating portion and an edge portion are formed using a thermoplastic liquid crystal polymer film as a raw material is provided, The method includes a step of heat-treating a portion of a thermoplastic liquid crystal polymer film that forms an edge portion, or an edge portion of a thermoplastic liquid crystal polymer molded article that has been shaped by molding the thermoplastic liquid crystal polymer film.

[0061] The portion that forms the edge portion of the thermoplastic liquid crystal polymer film refers to the portion where the edge portion is to be formed in the thermoplastic liquid crystal polymer film before the shaping step and in the thermoplastic liquid crystal polymer film during the shaping step.

[0062] For example, the manufacturing method of the acoustic diaphragm of the present invention may be to integrally mold the thermoplastic liquid crystal polymer film to form the vibration part and the edge part, or to manufacture the thermoplastic liquid crystal polymer film or molded body of the part corresponding to the vibration part and the thermoplastic liquid crystal polymer film or molded body of the part corresponding to the edge part separately, and bond them by thermocompression. When manufacturing the vibration part and the edge part separately, the thermoplastic liquid crystal polymer film or molded body that has been subjected to the heat treatment process described below may be bonded by thermocompression, or the heat treatment process may be performed after bonding the thermoplastic liquid crystal polymer film or molded body by thermocompression.

[0063] The thermocompression bonding may be performed by any method that can bond the vibration part and the edge part in a manner that allows practical use, and for example, the heating temperature during the thermocompression bonding may be in the range of (Tm-30) to (Tm+40)° C., and preferably about (Tm-20) to (Tm+30)° C., where Tm is the melting point of the thermoplastic liquid crystal polymer film. The pressure during the thermocompression bonding may be in the range of, for example, 0.5 to 10 MPa, and preferably 1 to 5 MPa.

[0064] (Heat treatment process) In the heat treatment step, the elastic modulus of the edge portion may be reduced by heat treatment of the portion forming the edge portion of the thermoplastic liquid crystal polymer film or the edge portion of the thermoplastic liquid crystal polymer molded body. The heat treatment step may be performed on the thermoplastic liquid crystal polymer film before the shaping step, on the thermoplastic liquid crystal polymer film during the shaping step, or on the thermoplastic liquid crystal polymer molded body after the shaping step. The inventors of the present invention have surprisingly found that the thermoplastic liquid crystal polymer film has a property that is completely different from that of conventional polymer materials, in that the elastic modulus is lowered while maintaining a high internal loss, probably because the molecular orientation of the thermoplastic liquid crystal polymer is relaxed by heat treatment. As a result, it has been found that by heat treating the portion corresponding to the edge portion of the thermoplastic liquid crystal polymer film or the thermoplastic liquid crystal polymer molded body, it is possible to simultaneously provide the required characteristic of a high elastic modulus of the vibration portion and the required characteristic of a low elastic modulus of the edge portion, even though the vibration portion and the edge portion are made of the same material.

[0065] The heat treatment can be carried out by a known method, but a method capable of locally heating is particularly preferred, and for example, a method of temperature control such as hot air heating, steam heating, heater heating, etc.; a method of thermal energy control such as laser heating, electron beam heating, ultrasonic heating, etc. For example, heater heating, laser heating, and ultrasonic heating are preferred from the viewpoint of locally controlling the heat treatment. Heating with a heater is preferred from the viewpoint of easy temperature control, and various heaters can be used depending on the shape of the acoustic diaphragm. For example, in the case of a circular acoustic diaphragm, a ring-shaped heater can be used. Ultrasonic heating and laser heating are also preferred in that they allow heating and cooling in a short time and heat only the contacting portion.

[0066] When temperature control is performed, the heating temperature can be appropriately adjusted depending on the desired elastic modulus, and may be, for example, (Tm-30) to (Tm+30)°C, preferably (Tm-25) to (Tm+20)°C, and more preferably (Tm-20) to (Tm+10)°C.

[0067] The heating time can be appropriately set depending on the heating temperature, but from the viewpoint of adjusting the elastic modulus of only the edge portion without changing the elastic modulus of the portions other than the heated portion, it may be 30 seconds to 30 minutes, preferably 2 minutes to 25 minutes, and more preferably 5 minutes to 20 minutes.

[0068] In the heating step, the portion of the thermoplastic liquid crystal polymer film or the thermoplastic liquid crystal polymer molded article corresponding to the vibration part may be heated, and in this case, the heating temperature for the portion corresponding to the edge part may be higher than the heating temperature for the portion corresponding to the vibration part. For example, the temperature difference between the heating temperature for the portion corresponding to the vibration part and the heating temperature for the portion corresponding to the edge part may be 5°C or more, preferably 8°C or more, and more preferably 10°C or more.

[0069] The heating step may be performed during the molding process in the shaping step or during the bonding process between the vibration part and the edge part. For example, a heat treatment for controlling the elastic modulus of the edge part may be performed simultaneously with the heating for molding or bonding. In that case, the heating temperature for the part corresponding to the edge part may be higher than the heating temperature for the part corresponding to the vibration part, and the temperature difference may be as described above.

[0070] In addition, when performing a thermal energy control process, for example, in ultrasonic heating, as shown in FIG. 4, an ultrasonic heating device places a thermoplastic liquid crystal polymer film or a thermoplastic liquid crystal polymer molded body 19 on an anvil 18 supported by a base 17, applies a load from a pressure device 20 to the part corresponding to the edge part, and applies ultrasonic vibration from the tip of a horn 21. In this example, the ultrasonic heating device applies vibration in a vertical direction Z perpendicular to the part corresponding to the edge part, which is the target part, from the tip of the horn 21. The horn 21 is connected to an ultrasonic vibrator 23 via a cone 22. The ultrasonic vibrator 23 controls the ultrasonic vibration by an ultrasonic oscillator 25 connected to a power source 24.

[0071] As shown in Figures 5 and 6, the horn 21 has a large diameter cylindrical portion 21a on the base end side, a truncated cone portion 21b that is a truncated cone shape that decreases in diameter from the tip edge of the large diameter cylindrical portion 21a downward, and a small diameter cylindrical portion 21c that extends downward from the tip edge of the truncated cone portion 21b. The small diameter cylindrical portion 21c is formed to have a smaller diameter than the large diameter cylindrical portion 21a. The large diameter cylindrical portion 21a, the truncated cone portion 21b, and the small diameter cylindrical portion 21c are coaxial and integrally provided. Vibration is applied from the tip of the small diameter cylindrical portion 21c to the portion corresponding to the edge portion.

[0072] In the thermal energy control treatment, from the viewpoint of adjusting the elastic modulus of the edge portion, the treatment conditions can be appropriately set according to the medium to which the thermal energy is applied, and for example, as the treatment conditions in the ultrasonic treatment, from the viewpoint of accelerating the start of melting, the oscillation frequency may be, for example, in the range of 10 to 150 kHz, preferably 28 to 120 kHz, and the amplitude may be, for example, in the range of 1 to 100 μm, preferably 5 to 20 μm.

[0073] The oscillation retention time during the contact of the horn in the ultrasonic treatment can be appropriately set according to the frequency and peak power, and may be, for example, 0.05 to 5 seconds, and preferably 0.1 to 1.0 seconds. The pressure when the horn is pressed can be appropriately set according to the thickness of the edge portion, and may be, for example, 0.05 to 1.0 MPa, and preferably 0.08 to 0.8 MPa. The output can be appropriately adjusted according to the size of the edge portion, and is, for example, in the range of 100 to 1000 W, and preferably 180 to 800 W. After the oscillation retention time of the horn is over, it is preferable to provide a predetermined cooling time to cool the edge portion, and the cooling time may be, for example, 0.1 seconds or more. The upper limit of the cooling time can be appropriately set within a range in which the edge portion can be cooled, and may be, for example, 10 seconds or less, preferably 5 seconds or less, more preferably 1 second or less, and particularly preferably 0.5 seconds or less.

[0074] The obtained thermoplastic liquid crystal polymer film or thermoplastic liquid crystal polymer molded article may be subjected to a coating treatment as necessary to form a coating layer as long as the thickness can be adjusted to a small value. The coating treatment is not particularly limited as long as the desired thickness can be adjusted, and the molded article may be coated by application, spraying, deposition, or the like. The coating treatment may be applied to at least one surface of the molded article. The coating treatment may also be applied to the surface of the vibration part and / or edge part.

[0075] The material forming the coating layer preferably contains a metal material, and examples of the metal material include aluminum, titanium, beryllium, magnesium, titanium boronide, duralumin, etc. The metal material may be coated by painting or spraying a metal powder using a binder, or may be coated by vapor deposition.

[0076] The thickness of the coating layer may be, for example, about 0.5 to 10 μm, preferably about 1 to 5 μm, and more preferably about 1 to 3 μm.

[0077] [Acoustic diaphragm] The acoustic diaphragm of the present invention is an acoustic diaphragm in which a vibrating part and an edge part located on the outer periphery of the vibrating part are made of a thermoplastic liquid crystal polymer having the same composition, and the elastic modulus E of the vibrating part measured by the nanoindentation method is d and the elastic modulus of the edge E e E d >E e Satisfy the relationship.

[0078] The acoustic diaphragm of the present invention may be formed by integrally molding the vibration part and the edge part with a single thermoplastic liquid crystal polymer film, or may be formed by separately manufacturing the thermoplastic liquid crystal polymer film or molding of the part corresponding to the vibration part and the part corresponding to the edge part, and joining them by thermocompression. From the viewpoint of suppressing the thickness variation and easy manufacturing, it is preferable that the acoustic diaphragm is formed by thermoplastic liquid crystal polymer, and the vibration part and the edge part located on the periphery of the vibration part are integrally molded.

[0079] The same composition means that the copolymerization composition of the thermoplastic liquid crystal polymer is substantially the same, and the molecular weight and crystal structure may be different. For example, when each part is manufactured using the same thermoplastic liquid crystal polymer film, the copolymerization composition of each part is substantially the same, and when they are integrally molded, it corresponds to the same composition. The copolymerization composition indicates the type of repeating unit constituting the thermoplastic liquid crystal polymer and their molar ratio.

[0080] The nanoindentation method measures the indentation load and indentation depth when an indenter is inserted vertically into the sample surface, and calculates the contact stiffness (S) and contact depth (h c ) and calculate the elastic modulus (Young's modulus). Each elastic modulus measured by the nanoindentation method is a value calculated by the method described in the Examples below.

[0081] For example, the acoustic diaphragm of the present invention has an elastic modulus E of the vibration part measured by the nanoindentation method. d and the elastic modulus of the edge E e Ratio of E d / E e may be 1.05 to 5.0. d / E e may be preferably 1.1 to 4.0, and more preferably 1.2 to 3.0.

[0082] In addition, in order to suppress split vibration and expand the reproduction frequency band, the acoustic diaphragm of the present invention has an elastic modulus E of the vibration part measured by the nanoindentation method. d However, it may be 6.0 to 15.0 GPa, preferably 6.5 to 14.0 GPa, and more preferably 7.0 to 13.0 GPa.

[0083] The acoustic diaphragm of the present invention has an elastic modulus E of the edge portion measured by the nanoindentation method from the viewpoint of maintaining the shape of the vibrating part and not interfering with the vibration. e However, for example, it may be 4.5 to 12.0 GPa, preferably 5.0 to 12.0 GPa, more preferably 5.5 to 11.0 GPa, and further more preferably 6.0 to 10.0 GPa.

[0084] The acoustic diaphragm of the present invention may simultaneously have different characteristics required for the vibration part and the edge part, i.e., high elastic modulus for the vibration part and low elastic modulus for the edge part. By having a high elastic modulus for the vibration part, for example, it is possible to suppress split vibration and expand the reproduction frequency band. Also, by having a low elastic modulus for the edge part, it is possible to support the outer periphery of the vibration part and hold it in the correct position, and to allow it to follow the movement of the vibration part without interfering with the movement.

[0085] In order to suppress the resonance peak caused by the divided vibration and to flatten the frequency characteristics, the acoustic diaphragm of the present invention may have an internal loss tan δ of the vibration part and the edge part both in the range of 0.03 to 0.08, preferably 0.04 to 0.08, and more preferably 0.05 to 0.08. The internal loss can be measured by dynamic viscoelasticity measurement (DMA) and is a value calculated by the method described in the examples below.

[0086] For example, the acoustic diaphragm of the present invention has an internal loss tan δ d and the internal loss tan δ of the edge e Ratio of tan δ d / tanδ e may be 0.8 to 1.2, and preferably 0.9 to 1.1.

[0087] In the acoustic diaphragm of the present invention, the thickness of the edge portion may be thinner than the thickness of the vibration portion in order to reduce the rigidity of the edge portion. For example, the difference in thickness in the acoustic diaphragm may be 10 μm or less, preferably 5 μm or less, and more preferably 3 μm or less. In addition, when a groove is provided in the edge portion, the groove portion is not included in the standard of the thickness difference.

[0088] As shown in FIG. 3, the thickness t1 of the vibration part 11 of the acoustic diaphragm 10 can be appropriately set according to the acoustic device to which the acoustic diaphragm 10 is attached, and may be selected from, for example, about 5 to 200 μm, preferably about 10 to 180 μm, and more preferably about 15 to 150 μm. In general, the larger the acoustic diaphragm 10, the thicker the film is required, and the smaller the acoustic diaphragm 10, the thinner the film is required. For example, the thickness t1 of the vibration part 11 of the acoustic diaphragm 10 is preferably 15 to 25 μm in the case of an earphone having a size of φ5 mm to φ15 mm, preferably 25 to 50 μm in the case of a headphone having a size of φ15 mm to φ40 mm, and preferably 75 to 150 μm in the case of a car speaker having a size of about φ100 mm.

[0089] The thickness t2 of the edge portion 12 of the acoustic diaphragm 10 can be set appropriately depending on the acoustic equipment to which the acoustic diaphragm 10 is attached, and may be, for example, about 3 to 200 μm, preferably about 5 to 170 μm, and more preferably about 10 to 150 μm.

[0090] The acoustic diaphragm of the present invention is made of a thermoplastic liquid crystal polymer, and the thermoplastic liquid crystal polymer film and molding have small changes in properties such as elastic modulus and internal loss up to the melting point even at temperatures above the glass transition temperature. For example, when used in car audio or smartphones, they may be exposed to high temperature environments of 150°C or higher, but the acoustic diaphragm of the present invention does not change elastic modulus or internal loss significantly even at such high temperatures, so it can be used in applications requiring heat resistance.

[0091] [Audio equipment] The acoustic device is not particularly limited as long as it is equipped with the acoustic diaphragm of the present invention, and examples thereof include devices in which a receiver holds an acoustic device directly to his / her ear to receive sound (e.g., headphones, earphones, etc.), devices in which a receiver holds an acoustic device close to his / her ear to receive sound (e.g., mobile phone, smartphone, etc.), and devices in which a receiver receives sound from an acoustic device while separated from a predetermined space (e.g., speakers, audio, radio, television, personal computer, car audio, etc.). For example, the acoustic diaphragm of the present invention has excellent environmental resistance characteristics such as heat resistance, and may be used in car audio, personal computer, etc. The acoustic device of the present invention may also be a full-range speaker. In addition, since the acoustic diaphragm of the present invention has a vibration part and an edge part formed of the same material, it may be used in a microspeaker that is required to be small and thin. The acoustic device of the present invention may be an electronic device equipped with the microspeaker (for example, a portable acoustic device such as a headphone, an earphone, or a portable speaker, a portable electronic device such as a mobile phone or a smartphone, or an electronic device such as a notebook computer). EXAMPLES

[0092] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples. In the following examples and comparative examples, various physical properties were measured by the following methods.

[0093] [Melting point] Using a differential scanning calorimeter (manufactured by Shimadzu Corporation), a sample of a predetermined size was taken from the thermoplastic liquid crystal polymer film used in the examples and placed in a sample container. The position of the endothermic peak that appeared when the temperature was raised from room temperature to 400°C at a rate of 10°C / min was determined as the melting point Tm of the thermoplastic liquid crystal polymer film.

[0094] Thickness Based on JIS K 7130 A method, the measurement was performed by mechanical scanning using a micrometer (MDC-MX, manufactured by Mitutoyo Corporation).

[0095] Elasticity Modulus The elastic modulus of the vibration part and edge part of the acoustic diaphragm obtained in the examples described later was calculated using the nanoindentation method as follows. The scanning probe microscope used was E-sweep manufactured by SII Nanotechnology, the nanoindentation device was TriboScope manufactured by Hysitron, and the diamond indenter was a regular triangular pyramid (Berkovich type) indenter (142.3°) manufactured by Hysitron. The temperature was 23°C, the humidity was 43°C, and the surface area was 100°C. % Under this environment, the load was set to 300 μN, the indentation depth was about 200 nm, and the indentation was performed for 3 seconds and then pulled out for 3 seconds. The load-displacement curve consisting of the load, hold, and unload regions was measured. The stiffness (S) was calculated from the slope of the unloading curve, and the contact depth (h c ) is calculated. h c =h t -ε(P / S) Here, h t is the measured indentation depth (nm), ε is a constant related to the indenter shape (0.75 for the Berkovich indenter), and P is the maximum load (μN). In addition, the contact projection area A is calculated by the following formula: cIt is calculated from: A=24.56h c 2 Then, the elastic modulus E is calculated by the following formula: s is the composite elastic modulus E r It is calculated from:

[0096]

number

[0097] Here, E i is the Young's modulus of the indenter, ν i is the Poisson's ratio of the indenter, ν s is the Poisson's ratio of the sample, and β is a constant determined by the shape of the indenter. For the vibration part and edge part, indentation was performed at 10 locations within an area of ​​10 μm × 10 μm, and the same measurement was performed at different locations (n ​​= 3), and the average was calculated to determine the elastic modulus of each part.

[0098] [Internal loss] A rectangular measurement sample (4 mm x 10 mm) was measured using a dynamic viscoelasticity measuring device (FT Rheospectra DVE-V4, manufactured by Rheology Inc.) at a frequency of 10 Hz, a heating rate of 3°C / min (-100°C to +300°C), and a strain of 0.025%. The imaginary part (E″: loss modulus) of the real part of the complex modulus obtained at 20°C (E': storage modulus) was calculated, and the internal loss (tan δ) was calculated from the ratio (E″ / E').

[0099] Example 1 A thermoplastic liquid crystal polymer film (manufactured by Kuraray Co., Ltd., "Vextar" (registered trademark), melting point 280°C, thickness 25 μm, SOR 1.10) was shaped by pressure molding at a temperature of 220°C and a pressure of 2 MPa to obtain a thermoplastic liquid crystal polymer molded product having the shape shown in Figures 2 and 3. The size of the vibration part was φ20 mm, and the overall size was φ40 mm. Only the portion corresponding to the edge of the thermoplastic liquid crystal polymer molded body was heat-treated at 275°C for 1 minute using a heater to obtain an acoustic diaphragm. Table 7 shows the results of the physical property measurements.

[0100] Example 2 An acoustic diaphragm was produced in the same manner as in Example 1, except that the heat treatment temperature was set to 280° C. Table 7 shows the results of measuring the physical properties.

[0101] Example 3 A thermoplastic liquid crystal polymer film (manufactured by Kuraray Co., Ltd., "Vextar" (registered trademark), melting point 305°C, thickness 25 μm, SOR 1.10) was shaped by pressure molding at a temperature of 220°C and a pressure of 2 MPa to obtain a thermoplastic liquid crystal polymer molding having the same shape as in Example 1. Only the edge portion of the thermoplastic liquid crystal polymer molded body was heat-treated at 300° C. for 1 minute using a heater to obtain an acoustic diaphragm. Table 7 shows the results of the physical property measurements.

[0102] Example 4 An acoustic diaphragm was produced in the same manner as in Example 1, except that the method of heat-treating the edge portion was changed to an ultrasonic heating device (manufactured by Nippon Avionics Co., Ltd., "HW-D250S-28", oscillation frequency: 28 kHz, amplitude: 10 μm, output: 180 W, pressure: 0.1 MPa, retention time: 1.0 second, cooling time: 0.1 second). Table 7 shows the physical property measurement results. As shown in FIG. 6, the horn shape in this example has a diameter dimension φ1 of 12 mm for the small diameter cylindrical portion 21c and a diameter dimension φ2 of 14 mm for the large diameter cylindrical portion 21a.

[0103] Comparative Example 1 A PET film (thickness 25 μm) was molded into the same shape as in Example 1 by pressure molding at a temperature of 120° C. and a pressure of 2 MPa, and then an aluminum plate (thickness 25 μm) with a diameter of 20 mm was attached to the vibration part of the molded body after molding with an epoxy adhesive with a thickness of 13 μm to obtain an acoustic diaphragm. The thickness of the vibration part was 50μm + 12.5μm = 62.5μm, and the weight of the entire acoustic diaphragm was about 0.16mg. Table 7 shows the physical property measurement results.

[0104] Comparative Example 2 An acoustic diaphragm was produced by attaching an aluminum plate to the vibration part with an epoxy adhesive in the same manner as in Comparative Example 1, except that a PEEK film (thickness 25 μm) was used instead of the PET film and shaped to a size of φ40 mm by pressure molding at a temperature of 150 °C and a pressure of 2 MPa. Table 7 shows the physical property measurement results.

[0105] [Table 7]

[0106] As shown in Table 7, the acoustic diaphragm using the thermoplastic liquid crystal polymer molded body of Examples 1 to 4 can have a high elastic modulus vibration part and a low elastic modulus edge part without a joint. In addition, even though the elastic modulus of the edge part is reduced, the internal loss does not change, and the internal loss is high in both the vibration part and the edge part. Furthermore, since the vibration part and the edge part are integrally molded, there is no difference in thickness between the vibration part and the edge part, and it is possible to reduce the overall weight.

[0107] On the other hand, in Comparative Examples 1 and 2, the elastic modulus is adjusted between the vibrating part and the edge part by bonding different materials. However, due to the presence of the aluminum plate and adhesive layer, the vibrating part is thicker and heavier, so the propagation velocity (E / ρ) 1 / 2 ) and the acoustic characteristics are insufficient. [Industrial Applicability]

[0108] The acoustic diaphragm of the present invention is useful as a member for use in various acoustic devices.

[0109] Although the preferred embodiment of the present invention has been described above with reference to the drawings, a person skilled in the art will easily imagine various changes and modifications within the obvious scope upon reading the specification. Therefore, such changes and modifications are interpreted as falling within the scope of the invention as defined by the claims. [Explanation of symbols]

[0110] 10... Acoustic diaphragm 11. Vibration section 12 Edge section 13. Pole piece 14. Voice coil 15...Magnetic material 16...Groove 17...Pedestal 18. Anvil 19. Thermoplastic liquid crystal polymer film or thermoplastic liquid crystal polymer molded product 20. Pressurizing device 21 Horn 21a Large diameter cylindrical section 21b: Cone frustum 21c Small diameter cylindrical section 22. Corn 23 Ultrasonic transducer 24...Power supply 25 Ultrasonic generator F: Ear side surface of acoustic diaphragm R: Surface of the acoustic diaphragm opposite the ear

Claims

1. An acoustic diaphragm in which a vibrating part and an edge part located on the outer periphery of the vibrating part are made of a thermoplastic liquid crystal polymer having the same composition, and the elastic modulus E of the vibrating part measured by a nanoindentation method is ｄ and the elastic modulus E of the edge portion ｅ E ｄ >E ｅ An acoustic diaphragm that satisfies the relationship.

2. 2. The acoustic diaphragm according to claim 1, wherein the elastic modulus E ｄ and the elastic modulus E of the edge portion ｅ The ratio of E ｄ / E ｅ An acoustic diaphragm, wherein the elastic modulus is 1.05 to 5.

0.

3. 3. The acoustic diaphragm according to claim 1, wherein the elastic modulus E ｄ The acoustic diaphragm has a modulus of 6.0 to 15.0 GPa.

4. The acoustic diaphragm according to any one of claims 1 to 3, wherein the elastic modulus E ｅ The acoustic diaphragm has a modulus of 4.5 to 12.0 GPa.

5. 5. The acoustic diaphragm according to claim 1, wherein the internal loss tan δ of the vibration portion and the edge portion is both within a range of 0.03 to 0.

08.

6. 6. The acoustic diaphragm according to claim 1, wherein a difference in thickness between the vibration portion and the edge portion within the acoustic diaphragm is 10 μm or less.

7. A method for manufacturing an acoustic diaphragm in which a vibration part and an edge part are formed using a thermoplastic liquid crystal polymer film as a raw material, A heat treatment step of heat-treating a portion of the thermoplastic liquid crystal polymer film or a molded body formed by molding the thermoplastic liquid crystal polymer film, the portion corresponding to the edge portion, The molecular orientation ratio (SOR) of the thermoplastic liquid crystal polymer film before the heat treatment step is 0.80 to 1.30; In the heat treatment process, the part corresponding to the edge part is heated at a higher temperature than the part corresponding to the vibration part of the thermoplastic liquid crystal polymer film or the molded body, or only the part corresponding to the edge part is heated.

8. The manufacturing method according to claim 7, wherein the heating temperature of the heat treatment is (Tm-30) to (Tm+30) ° C. (wherein Tm is the melting point of the thermoplastic liquid crystal polymer film).

9. The method for producing an acoustic diaphragm according to claim 7, wherein the heat treatment is an ultrasonic treatment.

10. An acoustic device comprising the acoustic diaphragm according to any one of claims 1 to 6.

11. 11. The audio device according to claim 10, which is a speaker, a headphone, or an earphone.

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