阅读说明：本技术 一种可用于发声装置的振膜及其制备方法、发声装置 (Vibrating diaphragm for sound production device, preparation method of vibrating diaphragm and sound production device ) 是由 王婷 李春 于 2021-06-18 设计创作，主要内容包括：本发明涉及一种可用于发声装置的振膜及其制备方法、发声装置。一种可用于发声装置的振膜包括至少一层聚酯基热塑性硫化橡胶层,所述聚酯基热塑性硫化橡胶由热塑性聚酯材料、橡胶、硫化剂和助剂经动态硫化制成；其中,所述振膜的厚度为25～300μm,所述聚酯基热塑性硫化橡胶在23℃环境下的损耗因子为0.05～0.25。本发明采用聚酯基热塑性硫化橡胶层,该材料利用热塑性聚酯材料和橡胶材料的协同作用获得了良好的声学性能,包括兼顾优异的刚度、回弹、阻尼、热稳定性等方面,而且可以热塑成型。(The invention relates to a vibrating diaphragm for a sound production device, a preparation method of the vibrating diaphragm and the sound production device. A vibrating diaphragm used for a sound generating device comprises at least one polyester-based thermoplastic vulcanized rubber layer, wherein the polyester-based thermoplastic vulcanized rubber is prepared by dynamically vulcanizing a thermoplastic polyester material, rubber, a vulcanizing agent and an auxiliary agent; wherein the thickness of the vibrating diaphragm is 25-300 μm, and the loss factor of the polyester-based thermoplastic vulcanized rubber at 23 ℃ is 0.05-0.25. The invention adopts the polyester-based thermoplastic vulcanized rubber layer, and the material obtains good acoustic properties by utilizing the synergistic effect of the thermoplastic polyester material and the rubber material, and can give consideration to the aspects of excellent rigidity, rebound, damping, thermal stability and the like, and can be subjected to thermoplastic forming.)

1. The vibrating diaphragm capable of being used for the sound production device is characterized by comprising at least one polyester-based thermoplastic vulcanized rubber layer, wherein the polyester-based thermoplastic vulcanized rubber is prepared by dynamically vulcanizing a thermoplastic polyester material, rubber, a vulcanizing agent and an auxiliary agent;

wherein the thickness of the vibrating diaphragm is 25-300 μm, and the loss factor of the polyester-based thermoplastic vulcanized rubber at 23 ℃ is 0.05-0.25.

2. The diaphragm of claim 1, wherein the weight ratio of the thermoplastic polyester material to the rubber in the polyester-based thermoplastic vulcanizate is 10:1 to 1: 1.

3. The diaphragm of claim 1, wherein the thermoplastic polyester material has a melting point of 160 ℃ to 250 ℃.

4. The diaphragm according to any one of claims 1 to 3, wherein the rubber includes one or more of nitrile rubber, hydrogenated nitrile rubber, silicone rubber, acrylate rubber, ethylene-acrylate rubber, and urethane rubber;

and/or the thermoplastic polyester material comprises one or more of thermoplastic polyester elastomer, polylactic acid, polycarbonate, polybutylene terephthalate and polyethylene terephthalate.

5. The diaphragm of any one of claims 1 to 3, wherein the loss factor of the polyester-based thermoplastic vulcanizate at 23 ℃ is 0.08 to 0.21;

and/or the storage modulus of the polyester-based thermoplastic vulcanized rubber at the temperature of 23 ℃ is less than or equal to 300 Mpa.

6. The diaphragm of any one of claims 1 to 3, wherein the storage modulus of the polyester-based thermoplastic vulcanizate is 9.7 to 45MPa at 23 ℃.

7. The diaphragm of any one of claims 1 to 3, wherein the thickness of the diaphragm is 30 to 200 μm.

8. The diaphragm of any one of claims 1 to 3, wherein the auxiliary agent includes at least one of an anti-aging agent, a plasticizer, a filler, and a lubricant;

and/or, the sulfurizing agent comprises dicumyl peroxide.

9. The diaphragm of any one of claims 1 to 3, wherein the diaphragm comprises only one layer of the polyester-based thermoplastic vulcanizate layer.

10. The diaphragm of any one of claims 1 to 3, wherein the diaphragm is a multi-layer stacked composite layer structure, and comprises an intermediate layer and two surface layers, the intermediate layer is a glue layer and is disposed between the two surface layers, and the two surface layers are independently selected from a thermoplastic elastomer layer or the polyester-based thermoplastic vulcanizate layer.

11. The diaphragm according to any one of claims 1 to 3, wherein the diaphragm is a multi-layer stacked composite structure including the polyester-based thermoplastic vulcanizate layer and the adhesive layer, the polyester-based thermoplastic vulcanizate layer and the adhesive layer are alternately stacked and the polyester-based thermoplastic vulcanizate layer is a surface layer.

12. A sound production device, comprising a vibration system and a magnetic circuit system matched with the vibration system, wherein the vibration system comprises a diaphragm and a voice coil combined on one side of the diaphragm, the magnetic circuit system drives the voice coil to vibrate to drive the diaphragm to produce sound, and the diaphragm adopts the diaphragm of any one of claims 1 to 11.

13. A sound production device is characterized by comprising a shell, a magnetic circuit system and a vibration system, wherein the magnetic circuit system and the vibration system are arranged in the shell, the vibration system comprises a voice coil, a first vibrating diaphragm and a second vibrating diaphragm, the top of the voice coil is connected with the first vibrating diaphragm, the magnetic circuit system drives the voice coil to vibrate so as to drive the first vibrating diaphragm to produce sound, two ends of the second vibrating diaphragm are respectively connected with the shell and the bottom of the voice coil, and the second vibrating diaphragm is the vibrating diaphragm in any one of claims 1-11.

Technical Field

The invention relates to the technical field of electroacoustic, in particular to a vibrating diaphragm for a sound generating device, a preparation method of the vibrating diaphragm and the sound generating device.

Background

With the increasing demands for the performance of speakers in the industry, more and more products are pursuing higher loudness, high-quality sound quality, high-level waterproofing, and the like. The existing loudspeaker diaphragm material mainly comprises engineering plastics such as PEEK and PAR or elastomer materials such as TPU and TPEE. Among them, engineering plastics such as PEEK and PAR have good temperature resistance, but the material resilience is poor, and the product is easy to produce membrane folding and cannot play a waterproof role. And the high temperature resistance of TPU, TPEE and other elastomer materials is poor. Therefore, the diaphragm materials commonly used in the industry all have disadvantages, and rubber is considered to be one of the materials with the hope of improving the insufficient performance of the diaphragm materials, and the rubber has the advantages of improving the thermal stability and the rebound resilience compared with engineering plastics and thermoplastic elastomer materials. For example, it is reported that an insulating protective layer of a cable is made by mixing rubber into a thermoplastic elastomer material, but since it is used as an insulating material, optimization of properties such as insulation, flame retardancy, etc. is more emphasized, and acoustic properties such as damping, lowest resonance frequency, etc. are not improved, resulting in failure to be used as a diaphragm.

The invention is therefore proposed.

Disclosure of Invention

The invention mainly aims to provide a vibrating diaphragm for a sound generating device, which adopts a polyester-based thermoplastic vulcanized rubber layer, obtains good acoustic performance by utilizing the synergistic effect of a thermoplastic polyester material and a rubber material, gives consideration to the aspects of excellent rigidity, resilience, damping, thermal stability and the like, and can be subjected to thermoplastic molding.

The invention also aims to provide a preparation method of the diaphragm, which only relates to conventional procedures, has simple flow and does not have harsh process conditions.

The third aspect of the invention aims to provide a sound production device composed of the diaphragm.

In order to achieve the above object, the present invention provides the following technical solutions.

According to the diaphragm for the sound generating device in the embodiment of the first aspect of the present invention, the diaphragm includes at least one polyester-based thermoplastic vulcanized rubber layer, and the polyester-based thermoplastic vulcanized rubber is made of a thermoplastic polyester material, rubber, a vulcanizing agent and an auxiliary agent through dynamic vulcanization;

the thickness of the vibrating diaphragm is 25-300 mu m, and the loss factor of the polyester-based thermoplastic vulcanized rubber at the temperature of 23 ℃ is 0.05-0.25.

According to some embodiments of the invention, the weight ratio of the thermoplastic polyester material and the rubber in the polyester-based thermoplastic vulcanizate is from 10:1 to 1: 1.

According to some embodiments of the invention, the thermoplastic polyester material has a melting point of 160 ℃ to 250 ℃.

According to some embodiments of the invention, the rubber comprises one or more of nitrile rubber, hydrogenated nitrile rubber, silicone rubber, acrylate rubber, ethylene-acrylate rubber, urethane rubber; and/or the thermoplastic polyester material comprises one or more of thermoplastic polyester elastomer, polylactic acid, polycarbonate, polybutylene terephthalate and polyethylene terephthalate.

According to some embodiments of the invention, the polyester-based thermoplastic vulcanizate has a loss factor in the range of 0.08 to 0.21 at 23 ℃; and/or the storage modulus of the polyester-based thermoplastic vulcanized rubber at the temperature of 23 ℃ is less than or equal to 300 Mpa.

According to some embodiments of the invention, the polyester-based thermoplastic vulcanizate has a storage modulus of 9.7 to 45Mpa at 23 ℃.

According to some embodiments of the invention, the diaphragm has a thickness of 30 to 200 μm.

According to some embodiments of the invention, the auxiliary agent comprises at least one of an antioxidant, a plasticizer, a filler, a lubricant; and/or, the sulfurizing agent comprises dicumyl peroxide.

According to some embodiments of the invention, the diaphragm comprises only one layer of the polyester-based thermoplastic vulcanizate.

According to some embodiments of the present invention, the diaphragm is a multi-layer stacked composite layer structure, which includes an intermediate layer and two surface layers, the intermediate layer is a glue layer and is disposed between the two surface layers, and the two surface layers are independently selected from a thermoplastic elastomer layer or the polyester-based thermoplastic vulcanizate layer.

According to some embodiments of the invention, the diaphragm is a multi-layer stacked composite structure, the diaphragm includes the polyester-based thermoplastic vulcanized rubber layers and rubber layers, the polyester-based thermoplastic vulcanized rubber layers and the rubber layers are alternately stacked, and the polyester-based thermoplastic vulcanized rubber layers are surface layers.

The sound production device according to the third aspect of the present invention includes a vibration system and a magnetic circuit system matched with the vibration system, the vibration system includes a diaphragm and a voice coil combined on one side of the diaphragm, the magnetic circuit system drives the voice coil to vibrate to drive the diaphragm to produce sound, and the diaphragm is the diaphragm according to the above embodiment of the present invention.

The sound production device according to the fourth aspect of the present invention includes a casing, and a magnetic circuit system and a vibration system that are disposed in the casing, where the vibration system includes a voice coil, a first diaphragm, and a second diaphragm, a top of the voice coil is connected to the first diaphragm, the magnetic circuit system drives the voice coil to vibrate to drive the first diaphragm to produce sound, two ends of the second diaphragm are respectively connected to the casing and a bottom of the voice coil, and the second diaphragm is the diaphragm according to the above embodiment of the present invention.

Compared with the prior art, the vibrating diaphragm is made of the polyester-based thermoplastic vulcanized rubber layer, and the polyester-based thermoplastic vulcanized rubber contains thermoplastic polyester materials and rubber materials with cross-linked network structures. The thermoplastic polyester material provides strength, resilience and thermoplastic property for the whole system, the rubber material provides heat-resistant stability, resilience and damping property for the whole system, and the two materials can be subjected to thermoplastic forming under the premise of meeting the requirements of the product on rigidity, resilience, damping and thermal stability, so that the comprehensive use performance of the vibrating diaphragm is greatly improved.

Drawings

Various other advantages and benefits will become apparent to those of ordinary skill in the art upon reading the following detailed description of the preferred embodiments. The drawings are only for purposes of illustrating the preferred embodiments and are not to be construed as limiting the invention.

FIG. 1 is a graph showing the change in storage modulus at different temperatures in examples and comparative examples;

fig. 2 is a schematic structural diagram of a speaker provided in the present invention;

FIG. 3 is a schematic diagram of the sound generating and vibrating unit of FIG. 2;

fig. 4 is a total harmonic distortion curve of the examples and comparative examples.

Detailed Description

Embodiments of the present invention will be described in detail below with reference to examples, but it will be understood by those skilled in the art that the following examples are only illustrative of the present invention and should not be construed as limiting the scope of the present invention. The examples, in which specific conditions are not specified, were conducted under conventional conditions or conditions recommended by the manufacturer. The raw materials, reagents or instruments used are not indicated by manufacturers, and all the raw materials, the reagents or the instruments are conventional products which can be obtained by commercial purchase or can be prepared according to the prior art.

The invention provides a vibrating diaphragm for a sound generating device, which comprises at least one polyester-based thermoplastic vulcanized rubber layer, wherein the polyester-based thermoplastic vulcanized rubber is prepared by dynamically vulcanizing a thermoplastic polyester material, rubber, a vulcanizing agent and an auxiliary agent; the thickness of the vibrating diaphragm is 25-300 mu m, and the loss factor of the polyester-based thermoplastic vulcanized rubber at the temperature of 23 ℃ is 0.05-0.25.

The invention utilizes the polyester-based thermoplastic vulcanized rubber layer to prepare the vibrating diaphragm, and the polyester-based thermoplastic vulcanized rubber not only contains thermoplastic polyester materials, but also contains rubber materials with cross-linked network structures. The thermoplastic polyester material provides strength, rebound resilience and thermoplastic property for the whole system, the rubber material provides heat-resistant stability, rebound resilience and damping property for the whole system, the two materials can obtain excellent acoustic performance under the synergistic action, particularly the aspects of rigidity, rebound resilience, damping, thermal stability and the like, and the combination can be subjected to thermoplastic forming.

Through tests, compared with a thermoplastic polyester material without rubber, the rubber-free thermoplastic polyester material has the advantages that the storage modulus, the loss factor and the lowest resonance frequency (F0) can be well balanced, the stability of the storage modulus in a wider temperature range is improved, the stability of the F0 in a wider voltage range is also improved, and the rubber-free thermoplastic polyester material is less prone to distortion.

The thickness of the diaphragm can be selected within the range of 25-300 μm, and can be adjusted according to F0 requirements, such as 25 μm, 50 μm, 100 μm, 150 μm, 200 μm, 250 μm, 300 μm, and the like. Because the intensity of vulcanized rubber is lower than that of a pure elastomer, a certain thickness needs to be matched in order to meet the rigidity required by vibration of the vibrating diaphragm. But too big thickness can lead to the loss in vibrating diaphragm vibration space, and too big weight that can increase the vibrating diaphragm of vibrating diaphragm thickness can reduce the sensitivity of vibrating diaphragm from this, more preferably, the thickness of vibrating diaphragm can be 30 ~ 200 mu m, and the required rigidity, resilience and damping nature of vibrating diaphragm vibration can be compromise well to the material this moment.

The loss factor of the polyester-based thermoplastic vulcanized rubber is data obtained by adopting a DMA (direct memory access) temperature scanning mode, a vibration frequency of 1Hz and a heating rate of 3 ℃/min, and can be randomly selected within the range of 0.05-0.25, such as 0.05, 0.1, 0.15, 0.2, 0.25 and the like, in cooperation with the thickness of a vibrating diaphragm. Generally, the higher the loss factor is, the better the damping property of the material is, and the improvement of the damping property of the vibrating diaphragm material is beneficial to reducing the polarization in the vibration process, reducing the product distortion and improving the listening yield. However, the improvement of the damping of the material will result in the reduction of the transient response of the diaphragm, and the sound quality will also be reduced, and the loss factor is more preferably 0.08-0.21, such as 0.08, 0.09, 0.10, 0.11, 0.12, 0.14, 0.15, 0.16, 0.17, 0.18, 0.19, 0.2, 0.21, etc. in combination with the modulus requirement of such materials.

In order to ensure the processability, rebound resilience and necessary processing strength of the polyester-based thermoplastic vulcanized rubber, the amount of the thermoplastic polyester material is preferably not less than that of the rubber, and the mass ratio of the thermoplastic polyester material to the rubber is usually 10:1 to 1:1, for example, 10:1, 9:1, 8:1, 7:1, 6:1, 5:1, 4:1, 3:1, 2:1, 1:1, etc. The content of the thermoplastic polyester material is further increased, the proportion of the rubber phase in the whole system is reduced, a network structure required for improving temperature resistance cannot be well formed, and the thermal stability of the material is not obviously improved. Further increase in rubber content reduces the thermoplastic properties of the material, increases the number of dispersed particles of rubber, and decreases the overall properties and film formability of the material.

In addition, the higher the content of the thermoplastic polyester material, the higher the modulus of the final product, and as mentioned above, the reduction of the rubber phase can reduce the high temperature resistance of the whole material, and the purpose of improving the high temperature resistance of the thermoplastic polyester material cannot be achieved. And the modulus has a correlation with the elasticity of the material, and the higher the modulus is, the lower the elasticity of the material is. In order to ensure excellent low-frequency performance and waterproof performance of the loudspeaker, the modulus of the polyester-based thermoplastic vulcanized rubber at 23 ℃ is generally less than or equal to 300MPa, such as 250MPa, 200MPa, 150MPa, 100MPa, 50MPa, 10MPa, 5MPa and the like, preferably less than or equal to 150MPa, and more preferably 9.7-45 MPa.

In order to ensure that the diaphragm has good thermal stability, the melting point of the thermoplastic polyester material selected by the invention is usually between 160 ℃ and 250 ℃, and can be 160 ℃, 170 ℃, 180 ℃, 190 ℃, 200 ℃, 210 ℃, 220 ℃, 230 ℃, 240 ℃ and the like. If the melting point is lower than 160 ℃, the requirements of long-term vibration and temperature resistance of the product cannot be met, the melting point is too high, the dispersibility of the product and rubber during dynamic vulcanization is poor, and the overall material performance is reduced. The thermoplastic polyester material may comprise one or more of a thermoplastic polyester elastomer, polylactic acid, polycarbonate, polyglycolic acid, polyhydroxyalkanoate, polybutylene terephthalate. Along with the improvement of sound quality and waterproof requirements, the loudspeaker diaphragm has better elasticity and flexibility and better product performance, and the thermoplastic polyester material is preferably thermoplastic polyester elastomer material (TPEE).

The rubber of the invention can comprise one or more of nitrile rubber, hydrogenated nitrile rubber, silicone rubber, acrylate rubber, ethylene-acrylate rubber and polyurethane rubber. At least one of an acrylate rubber containing an ester group and an ethylene-acrylate rubber is preferable in view of compatibility of the rubber with the thermoplastic polyester material.

The auxiliary agent comprises at least one of an anti-aging agent, a plasticizer, a filler and a lubricant to improve the comprehensive performance of the material or improve the processability, and the specific composition can be the anti-aging agent, the plasticizer, the filler or the lubricant, or the combination of the anti-aging agent and the plasticizer, or the combination of the anti-aging agent and the filler, or the combination of the anti-aging agent and the lubricant, or the combination of the anti-aging agent, the plasticizer, the filler and the lubricant.

The vulcanizing agent comprises at least one of trimercapto-s-triazine vulcanizing system, polyamine, organic acid, ammonium salt, organic acid ammonium salt, dithiocarbamate, imidazole/anhydride, isocyanuric acid/quaternary salt, sulfur/accelerator and peroxide, preferably peroxide, such as dicumyl peroxide (DCP), di-tert-butyl peroxide (DTBP) and the like. The rubber raw rubber is 100 parts by mass, and the addition amount of the vulcanizing agent is preferably 0.5-5 parts by mass, for example, 0.5 part, 1 part, 1.5 parts, 2 parts, 2.5 parts, 3 parts, 3.5 parts, 4 parts, 4.5 parts, 5 parts and the like, and more preferably 1 part. The cross-linking agent in parts by mass can ensure that the rubber raw rubber is fully cross-linked and avoid the toughness loss of the material caused by overhigh cross-linking degree.

The auxiliary crosslinking agent comprises at least one of trimethylolpropane triacrylate, trimethylolpropane trimethacrylate, N '-m-phenylene bismaleimide, diallyl phthalate, triallyl isocyanate and triallyl cyanate, and preferably N, N' -m-phenylene bismaleimide. The content of the co-crosslinking agent is 0.1 to 20 parts by mass, for example, 0.5 part, 1 part, 2 parts, 3 parts, 4 parts, 5 parts, 7 parts, 10 parts, 13 parts, 15 parts, 20 parts, etc., more preferably 2 parts, based on 100 parts by mass of the raw rubber. The cross-linking agent in the proportion range can play a good cross-linking effect, so that the vibrating diaphragm has sufficient hardness and resilience.

The antioxidant comprises at least one of antioxidant N-445, antioxidant 246, antioxidant 4010, antioxidant SP, antioxidant RD, antioxidant ODA, antioxidant OD and antioxidant WH-02, preferably antioxidant WH-02. When the mass part of the raw rubber is 100 parts, the addition amount of the antioxidant is preferably 0.5 to 10 parts, for example, 0.5 part, 1 part, 2 parts, 3 parts, 4 parts, 5 parts, 7 parts, 10 parts and the like, and more preferably 3 parts. The addition of the anti-aging agent can ensure that the diaphragm material can still ensure good mechanical properties of the material in a long-term high-temperature or high-temperature damp-heat environment, and the material performance can not be reduced due to the excessive addition amount.

The plasticizer comprises at least one of aliphatic dibasic acid esters, phthalic acid esters, benzene polyacid esters, benzoic acid esters, polyol esters, chlorinated hydrocarbons, epoxy, citric acid esters and polyesters, and preferably polyesters. When the raw rubber is 100 parts by mass, the amount of the plasticizer to be added is preferably 1 to 13 parts by mass, for example, 1 part, 2 parts, 3 parts, 4 parts, 5 parts, 7 parts, 10 parts, 13 parts, and the like, and more preferably 10 parts. The plasticizer is added to reduce the acting force among rubber molecules, thereby reducing the glass transition temperature of the rubber, leading the rubber to have plasticity and fluidity, and being convenient for the molding operations such as rolling, extrusion and the like.

The lubricant comprises stearic acid and at least one of stearate, octadecyl amine and alkyl phosphate, and alpha-octadecyl-omega-hydroxy polyoxyethylene phosphate, preferably stearate. When the raw rubber is 100 parts by mass, the lubricant is 0.5-5 parts by mass, for example, 0.5 part, 1 part, 2 parts, 3 parts, 4 parts, 5 parts, etc., more preferably 1.5 parts. The addition of the lubricant can reduce the adhesion of the material and the die during the forming processing of the vibrating diaphragm, and the die is easy to demould. The addition amount is too large, and the lubricant can be separated out of the surface after long-term use, so that the bonding of the diaphragm and other parts is influenced.

The filler includes at least one of carbon black, silica, talc, precipitated calcium carbonate, and barium sulfate. The materials are added into the rubber crude rubber in the form of powder. When the rubber raw rubber is 100 parts by mass, the amount of the filler added is preferably 5 to 30 parts, for example, 5 parts, 7 parts, 10 parts, 13 parts, 15 parts, 20 parts, 25 parts, 30 parts, and the like, and more preferably 10 parts. The range of the proportion enables the diaphragm to have good hardness, tensile strength and resilience. Because polyester-based thermoplastic vulcanized rubber can well give consideration to the modulus and resilience required by vibration of the diaphragm and has relatively high damping property, the polyester-based thermoplastic vulcanized rubber can be used for preparing the diaphragm of a single-layer film and can also be attached to composite films of other layers (such as an adhesive layer, a plastic layer, a thermoplastic elastomer layer and the like).

When the vibrating diaphragm is a composite film, the vibrating diaphragm comprises an intermediate layer and two surface layers, wherein the intermediate layer is an adhesive layer and is arranged between the two surface layers, and the two surface layers are independently selected from a thermoplastic elastomer layer or a polyester-based thermoplastic vulcanized rubber layer. Specifically, the upper and lower surface layers may be polyester-based thermoplastic vulcanizate layers, or the upper and lower surface layers may be thermoplastic elastomer layers, or one of the surface layers may be a polyester-based thermoplastic vulcanizate layer and the other surface layer may be a thermoplastic elastomer layer.

For the adhesive layer in the composite film, it may be an adhesive typical in the art, such as one or more of a silicone adhesive layer, an acrylic adhesive layer, preferably a pressure sensitive adhesive film. The pressure-sensitive adhesive film is convenient to use, and the lamination among multiple layers can be realized through a simple composite process.

The diaphragm of the present invention may also be a composite structure: the rubber layer is composed of the polyester-based thermoplastic vulcanized rubber layer and a rubber layer, wherein the polyester-based thermoplastic vulcanized rubber layer and the rubber layer are alternately stacked and the polyester-based thermoplastic vulcanized rubber layer is a surface layer. For example, the diaphragm may be a three-layer composite structure including two polyester-based thermoplastic vulcanizate layers and one glue layer disposed between the two polyester-based thermoplastic vulcanizate layers to connect the two polyester-based thermoplastic vulcanizate layers together, i.e., the diaphragm is formed in a structure of polyester-based thermoplastic vulcanizate layer + glue layer + polyester-based thermoplastic vulcanizate layer. For another example, the diaphragm may also be a five-layer composite structure, which includes three polyester-based thermoplastic vulcanized rubber layers and two rubber layers, and both outer surfaces of each rubber layer are polyester-based thermoplastic vulcanized rubber layers, so that the diaphragm is formed into a structure of polyester-based thermoplastic vulcanized rubber layer + polyester-based thermoplastic vulcanized rubber layer.

For the preparation of the polyester-based thermoplastic vulcanizates of the present invention, which involve only conventional procedures, there are included: and blending other raw materials except the vulcanizing agent, then adding the vulcanizing agent for dynamic vulcanization, extruding to obtain the polyester-based thermoplastic vulcanized rubber, and finally optionally pasting the polyester-based thermoplastic vulcanized rubber and other layers to form the vibrating diaphragm.

Wherein, the technological conditions of dynamic vulcanization have certain influence on the performance of the polyester-based thermoplastic vulcanized rubber, and the preferable process is as follows: firstly, preparing rubber master batch (weighing various materials according to a calculated formula, adding an anti-aging agent, a plasticizer, a filler, a lubricant and the like into raw rubber for mixing), then adding the rubber master batch into a thermoplastic polyester material in a molten state for mixing, after uniformly mixing, sequentially adding vulcanization aids such as an auxiliary crosslinking agent, a vulcanizing agent and the like, and mixing for 3-10 min to prepare the dynamic vulcanized rubber.

The diaphragm provided by the invention can form a sound production device with any structure, such as the following typical sound production devices: the vibration system comprises a vibration system and a magnetic circuit system matched with the vibration system, wherein the vibration system comprises a vibrating diaphragm and a voice coil combined on one side of the vibrating diaphragm. When the sound generating device works, the voice coil can vibrate up and down to drive the vibrating diaphragm to vibrate under the action of the magnetic field force of the magnetic circuit system after being electrified, and the vibrating diaphragm can generate sound during vibration.

According to another embodiment of the present invention, the sound generating device may include a casing, and a magnetic circuit system and a vibration system disposed in the casing, the vibration system may include a voice coil, a first diaphragm, and a second diaphragm, a top of the voice coil is connected to the first diaphragm, the magnetic circuit system drives the voice coil to vibrate to drive the first diaphragm to generate sound, and two ends of the second diaphragm are respectively connected to the casing and a bottom of the voice coil. The second diaphragm may be the diaphragm according to the above embodiment of the present invention.

That is, the first diaphragm may be used to vibrate and generate sound, and the second diaphragm may be used to balance the vibration of the voice coil. Particularly, when sound generating mechanism during operation, the voice coil loudspeaker voice coil can vibrate in order to drive first vibrating diaphragm vibration from top to bottom under magnetic field effect of magnetic circuit after the voice coil loudspeaker voice coil circular telegram, can carry out the sound production during first vibrating diaphragm vibration. The second vibrating diaphragm also can follow the voice coil loudspeaker voice coil and vibrate from top to bottom, because the both ends of second vibrating diaphragm link to each other with the bottom of casing and voice coil loudspeaker voice coil respectively, the vibration of voice coil loudspeaker voice coil can be balanced to the second vibrating diaphragm, can prevent that the phenomenon of polarization from appearing in the voice coil loudspeaker voice coil to can promote sound generating mechanism's sound producing effect.

It should be noted that, the first diaphragm and the second diaphragm may be both the diaphragms in the above embodiments of the present invention, or one of the first diaphragm and the second diaphragm may be the diaphragm in the above embodiments of the present invention, and the present invention is not limited to this specifically. The following description is made in conjunction with the embodiments.

Examples 1 to 3

Examples 1 to 3 were all prepared by the following method using the amounts of the materials shown in Table 1 to form a polyester-based thermoplastic vulcanizate layer. The method comprises the following specific steps:

first, blending

Adding a thermoplastic polyester elastomer (the hardness is about 45D, and the melting point is 200 ℃ of the thermoplastic polyester elastomer of a polyester soft segment), ethylene-acrylate rubber (the mass ratio of a polyethylene block to polyacrylate is 5:1), an anti-aging agent, a plasticizer, a filler and a lubricant into an extruder, blending, setting the screw temperature to be 160-250 ℃, and uniformly mixing.

Second, dynamic vulcanization

And continuously adding a proper amount of vulcanizing agent into the mixture, and carrying out dynamic vulcanization for 5-10 min to obtain the corresponding polyester-based thermoplastic vulcanized rubber layer.

Comparative example

The thermoplastic polyester elastomer used in example 1 was directly selected.

The raw material ratios in examples 1 to 3 are shown in Table 1.

Table 1 raw material amounts (in parts by weight)

	Example 1	Example 2	Example 3
				Thermoplastic polyester elastomer	100	100	100
Ethylene-acrylate rubber	100	42.8	11
				Dicumyl peroxide (vulcanizing agent)	1	0.43	0.11
N, N' -m-phenylene bismaleimide (auxiliary cross-linking agent)	2	0.86	0.22
				Polyester plasticizer TP-95 (plasticizer)	10	4.28	1.1
Antiager WH-02 (antiager)	3	1.3	0.33
				Zinc stearate (Lubricant)	1.5	0.64	0.16
Silicon dioxide (Filler)	10	4	1

Detecting the change of storage modulus of different materials with temperature and loss factor at normal temperature

The test method comprises the following steps: a flat rectangular sample strip with the width of 5-10 mm is taken from the film by using a cutter or a craft blade, the test is carried out by adopting the ASTM D412-2016 standard, the test vibration frequency is 1Hz, the temperature rise rate is 3 ℃/min, and the test temperature of the loss factor is 23 ℃.

As a result:

as shown in fig. 1, with the addition of the rubber phase, the modulus stability of TPEE is improved, especially, the improvement is obvious in the range of 50 ℃ to 150 ℃, and the modulus stability is better with the increase of the rubber content, i.e., example 1 is better than example 2 in the aspect of modulus stability than example 3, and examples 1 to 3 are all better than comparative examples. As shown in Table 2, the loss factor of the polyester-based thermoplastic vulcanizate tends to increase with increasing rubber component ratio, but the modulus of the material decreases.

In order to achieve good performance and sound quality, the diaphragm needs to have proper rigidity and damping performance when vibrating, and as can be seen from table 2 and the results in fig. 1, the presence of the rubber phase contributes to improving the damping performance of the material and the stability of the modulus at high temperature, but the modulus loss at room temperature is significant. At the same time, as the rubber phase increases, the hot workability of the material decreases. Example 2 has better performance and processability when applied to a diaphragm compared to examples 1 and 3, and example 2 is selected to be used for manufacturing and testing a loudspeaker.

TABLE 2

Scheme(s)	Storage modulus @23 deg.C	Storage modulus @70 deg.C	Loss factor @23 deg.C
				Comparative example	71	40	0.04
Example 1	9.7	6.1	0.21
				Example 2	23	12	0.12
Example 3	45	19	0.08

F0 and total harmonic distortion curves for testing speakers made of different materials

1. Making loudspeakers

The materials in example 2 and comparative example were selected to make diaphragms, respectively. Wherein, the diaphragms in the embodiment 2 and the comparative example both adopt single-layer structures, the embodiment 2 adopts the prepared polyester-based thermoplastic vulcanized rubber, and the comparative example adopts thermoplastic polyester elastomer. To meet the close product F0, the comparative example TPEE had a thickness of 50 μm and the polyester-based thermoplastic vulcanizate film of example 2 had a thickness of 90 μm. The manufacturing method of the diaphragm in the embodiment 2 is the same as that in the comparative example, and specifically includes the following steps:

the above materials are placed on a hot press molding machine for secondary molding, a required diaphragm shape is prepared, and the diaphragm shape is cut to the product size and then assembled into a micro-speaker unit together with a voice coil, a magnetic circuit system and other components (as shown in fig. 2 and 3).

2. The test method comprises the following steps:

product performance tests were performed on micro-Speakers (SPK) equipped with the diaphragms in example 2 and comparative example described above, respectively. The micro-speaker adopts the structure as shown in fig. 2, and comprises a vibration system and a magnetic circuit system matched with the vibration system, wherein the vibration system comprises a vibrating diaphragm and a voice coil combined on one side of the vibrating diaphragm. The loudspeaker vibration unit is shown in fig. 3, and those skilled in the art can make corresponding adjustments according to actual product requirements. For example, as shown in fig. 2 and 3, the diaphragm 1 is composed of a corrugated portion 11 and a dome portion 12, and the thermoplastic polyester elastomer layer may be located in the corrugated portion 11 of the diaphragm, or in the corrugated portion 11 and the dome portion 12. The folded ring part 11 protrudes to one side far away from the voice coil 2; the ball top part 12 is connected with the corrugated part 11; the centering support plate is arranged in the vibration system, so that the polarization resistance of the vibration system can be improved.

As a result:

the results of comparing F0 (shown in table 3) at different voltages show that as the test voltage increases, the decrease of F0 decreases with the increase of voltage, and that the decrease of F0 in example 2 is lower with the increase of voltage, which indicates that the stability of F0 in example is better and the performance is more stable. This phenomenon is probably because as the voltage increases, the local heat generation of the voice coil increases, the modulus of the material decreases, and since the polyester-based thermoplastic vulcanizate diaphragm has excellent heat stability relative to the TPEE diaphragm, the relative rate of change of the solid modulus decreases, and the F0 fluctuation of the product is relatively small.

TABLE 3

Scheme(s)	F0,2V/Hz	F0,3V(Hz)	F0,5V(Hz)
				Comparative example	968	944	916
Example 2	961	951	935

As shown in fig. 4, example 2 has a lower THD at the same voltage, and as the test voltage increases, the THD of example 2 increases to a lesser extent than the comparative product. This is probably because as the test voltage increases, the degree of decrease in F0 of the product of example 2 is relatively small, the variation in the overall performance of the product is small, and the displacement fluctuation of the product vibration is smooth, so that the distortion does not rise significantly. While the comparative product showed a significant decrease in product F0 with increasing test voltage, plus the material had lower damping than example 2, and thus the distortion increased more significantly (especially with increasing test voltage from 3V to 5V).

The above description is only for the preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope of the present invention are included in the scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the appended claims.