The diaphragm of the sound-generating device and its preparation method, the sound-generating device

Abstract

This application discloses a diaphragm for a sound-generating device and its preparation method, as well as the sound-generating device itself. The diaphragm comprises at least one microporous polyurethane elastomer film layer, which includes a polyurethane elastomer and a micropore-forming material. The microporous polyurethane elastomer film layer has micropores. The micropore-forming material includes inorganic hollow microspheres, with the content of inorganic hollow microspheres accounting for 5wt% to 50wt% of the total amount of the microporous polyurethane elastomer film layer. The average pore size of the micropores is 1μm to 60μm, and the loss factor of the microporous polyurethane elastomer film layer at room temperature is ≤0.15. The diaphragm of this application, by incorporating inorganic hollow microspheres into the polyurethane elastomer to form a microporous polyurethane elastomer film layer, not only reduces the density of the diaphragm and improves the mid-frequency sensitivity of the sound-generating device, but also, by controlling the amount of inorganic hollow microspheres added, enables the diaphragm material to have suitable damping, balancing the strength and transient resilience required during diaphragm vibration.

Description

Technical Field

[0001] This application relates to the field of electroacoustic technology, and more specifically, to a diaphragm for a sound-generating device, a method for preparing the diaphragm thereon, and a sound-generating device using the diaphragm. Background Technology

[0002] With the development of the industry, wearable electronic products (such as headphones, watches, AR, VR, etc.) have placed higher demands on the sound quality, reliability, and stability of sound-generating devices. Currently, the industry mainly uses thermoplastic elastomer materials (such as thermoplastic polyurethane elastomers and thermoplastic polyester elastomers) and their composite materials, as well as rubber materials (such as silicone rubber and NBR). Thermoplastic elastomer diaphragm materials generally suffer from insufficient high-temperature resistance; as listening time increases, the diaphragm's fatigue resistance becomes insufficient, leading to a decline in sound quality.

[0003] While rubber diaphragm materials offer significantly improved temperature resistance, their modulus is considerably lower compared to thermoplastic elastomers. To achieve the desired performance and sound quality, the diaphragm thickness must be more than double that of thermoplastic elastomers. The higher density of rubber due to fillers and other factors, combined with increased thickness, severely reduces the sensitivity of the entire vibration system. Furthermore, the molding process of rubber diaphragms involves the formation of a network polymer, resulting in significant molding shrinkage. Diaphragm materials with high shrinkage rates will exhibit substantial differences between the mechanical dimensions of the finished product and the design values; the greater the shrinkage, the greater the impact of the manufacturing process and the greater the rate of dimensional change.

[0004] Currently, the polyurethane foaming industry mainly uses chemical or physical foaming methods by adding foaming agents and other foaming aids to polyurethane elastomers. However, due to the relatively thin diaphragm materials used in sound-generating devices, simply using the above methods requires extremely strict process requirements to ensure the consistency and uniformity of the foam cells, such as the precision and stability of external pressure and temperature control. Especially for diaphragms with a thickness of less than 100μm, it is difficult to guarantee the batch stability of the foaming material, resulting in low product yield and poor stability.

[0005] Therefore, a new technical solution is needed to address the above problems. Summary of the Invention

[0006] One object of this application is to provide a diaphragm for a sound-generating device.

[0007] Another objective of this application is to provide a method for preparing the aforementioned diaphragm.

[0008] Another object of this application is to provide a sound-generating device composed of the aforementioned diaphragm.

[0009] According to the diaphragm of the sound-generating device according to the first aspect of this application, the diaphragm includes at least one microporous polyurethane elastomer film layer, the microporous polyurethane elastomer film layer includes a polyurethane elastomer and a micropore-forming material, the microporous polyurethane elastomer film layer has micropores; wherein, the micropore-forming material includes inorganic hollow microspheres, the content of the inorganic hollow microspheres accounts for 5wt% to 50wt% of the total amount of the microporous polyurethane elastomer film layer, the average pore size of the micropores is 1μm to 60μm, and the loss factor of the microporous polyurethane elastomer film layer at room temperature is ≤0.15.

[0010] According to some embodiments of this application, the particle size of the inorganic hollow microspheres is 1 μm to 60 μm, and the distribution density of the inorganic hollow microspheres in the microporous polyurethane elastomer film is 0.35 g / cm³. 3 ~0.9g / cm 3 .

[0011] According to some embodiments of this application, the density of the microporous polyurethane elastomer film is 0.6 g / cm³. 3 ~1.15g / cm 3 .

[0012] According to some embodiments of this application, the polyurethane elastomer is a compounded polyurethane elastomer.

[0013] According to some embodiments of this application, the polyurethane elastomer is one or more of polyester polyurethane elastomers, polycarbonate polyurethane elastomers, and polyether ester polyurethane elastomers.

[0014] According to some embodiments of this application, the tensile strength of the microporous polyurethane elastomer film is greater than 10 MPa, and the elongation at break is greater than 300%.

[0015] According to some embodiments of this application, the micropore-forming material further includes a foaming agent, which is added to the polyurethane elastomer to form the micropores.

[0016] According to the second aspect of this application, the method for preparing the diaphragm of the sound-generating device includes: adding a vulcanizing agent, inorganic hollow microspheres and other compounding agents to a polyurethane elastomer, and mixing them to obtain a mixture; placing the mixture on a diaphragm forming mold, and hot-pressing it to obtain the diaphragm.

[0017] According to a third aspect of this application, a method for preparing a diaphragm for a sound-generating device includes: adding a vulcanizing agent and other compounding agents to a polyurethane elastomer and mixing them to obtain a mixture; dissolving the mixture and inorganic hollow microspheres in a solvent to obtain a mixed slurry, controlling the solid content of the mixed slurry to be between 15% and 45%; coating the mixed slurry to prepare a film; and placing the film on a diaphragm forming mold and hot-pressing it to obtain the diaphragm.

[0018] According to some embodiments of this application, the hot pressing molding temperature is 80℃~200℃, the molding time is 50s~600s, and the molding pressure is 1MPa~20MPa.

[0019] According to some embodiments of this application, the shrinkage rate of the diaphragm before and after molding is 1.0% to 2.5%.

[0020] According to some embodiments of this application, the amount of the vulcanizing agent added accounts for 0.1wt% to 10wt% of the total amount of the mixture, and the vulcanizing agent is one or more of peroxide vulcanizing agents and sulfur vulcanizing agents.

[0021] According to some embodiments of this application, the other compounding agents include at least one of reinforcing fillers, vulcanizing accelerators, plasticizers, anti-hydrolysis agents, antioxidants, foaming agents, and compatibilizers.

[0022] A sound-generating device according to a fourth aspect of this application includes a vibration system and a magnetic circuit system cooperating with the vibration system. The vibration system includes a diaphragm and a voice coil coupled to one side of the diaphragm. The magnetic circuit system drives the voice coil to vibrate so as to drive the diaphragm to generate sound. The diaphragm is the diaphragm according to the above-described embodiment of this application.

[0023] A sound-generating device according to a fifth aspect embodiment of this application includes a housing and a magnetic circuit system and a vibration system disposed within the housing. The vibration system includes a voice coil, a first diaphragm, and a second diaphragm. The top of the voice coil is connected to the first diaphragm. The magnetic circuit system drives the voice coil to vibrate so as to drive the first diaphragm to generate sound. The two ends of the second diaphragm are respectively connected to the housing and the bottom of the voice coil. The second diaphragm is the diaphragm according to the above embodiment of this application.

[0024] According to the embodiments of the sound-generating device of this application, the diaphragm is made by adding inorganic hollow microspheres into a polyurethane elastomer to form a microporous polyurethane elastomer film layer. The process control is simple, the resulting micropores are uniformly distributed and dimensionally stable, and the diaphragm material has excellent stability. This not only reduces the density of the diaphragm and improves the mid-frequency sensitivity of the sound-generating device, but also allows the diaphragm material to have appropriate damping by controlling the amount of inorganic hollow microspheres added. This balances the strength and transient resilience required during diaphragm vibration. Therefore, the sound-generating device using the diaphragm of this application has superior sound quality.

[0025] Other features and advantages of this application will become clear from the following detailed description of exemplary embodiments with reference to the accompanying drawings. Attached Figure Description

[0026] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments of the present application and, together with their description, serve to explain the principles of the present application.

[0027] Figure 1 The loudness test curves (SPL curves) of Example 1, Comparative Example 1 and Comparative Example 2 at different frequencies are shown.

[0028] Figure 2 This is a cross-sectional view of the microporous polyurethane elastomer film layer of the diaphragm of the sound-generating device according to an embodiment of this application;

[0029] Figure 3 This is a schematic diagram of the overall structure of the sound-generating device according to an embodiment of this application;

[0030] Figure 4 This is a partial structural schematic diagram of a sound-generating device according to an embodiment of this application;

[0031] Figure 5 This is a cross-sectional view of a sound-generating device according to an embodiment of this application;

[0032] Figure 6 This is an exploded view of a sound-generating device according to an embodiment of this application.

[0033] Figure Labels

[0034] Sound-generating device 100;

[0035] Housing 10; Voice coil 11; First diaphragm 12; Second diaphragm 13; Magnetic circuit system 14;

[0036] Diaphragm 15; Folded ring 151; Top of sphere 152. Detailed Implementation

[0037] Various exemplary embodiments of the present application will now be described in detail with reference to the accompanying drawings. It should be noted that, unless otherwise specifically stated, the relative arrangement, numerical expressions, and values ​​of the components and steps set forth in these embodiments do not limit the scope of the present application.

[0038] The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the scope of this application and its application or use.

[0039] Techniques, methods, and equipment known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques, methods, and equipment should be considered part of the specification.

[0040] In all the examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may have different values.

[0041] It should be noted that similar labels and letters in the following figures indicate similar items; therefore, once an item is defined in one figure, it does not need to be discussed further in subsequent figures.

[0042] The diaphragm of the sound-generating device according to an embodiment of this application is described in detail below with reference to the accompanying drawings.

[0043] According to an embodiment of this application, the diaphragm of the sound-generating device comprises at least one microporous polyurethane elastomer film layer. The microporous polyurethane elastomer film layer includes a polyurethane elastomer and a micropore-forming material, and has micropores. The micropore-forming material includes inorganic hollow microspheres, the content of which is 5wt% to 50wt% of the total amount of the microporous polyurethane elastomer film layer. The average pore size of the micropores is 1μm to 60μm, and the loss factor of the microporous polyurethane elastomer film layer at room temperature is ≤0.15.

[0044] The diaphragm of the sound-generating device according to the embodiments of this application can be composed of at least one layer of microporous polyurethane elastomer film. Specifically, the diaphragm in this application can be a single-layer structure or a multi-layer composite structure. When the diaphragm is a single-layer structure, it is made of one layer of microporous polyurethane elastomer film of this application. When the diaphragm is a multi-layer composite structure, it includes at least one layer of microporous polyurethane elastomer film, and the diaphragm is composed of microporous polyurethane elastomer film layer combined with film layers of other materials. Optionally, when the diaphragm contains multiple layers of microporous polyurethane elastomer film, adjacent microporous polyurethane elastomer film layers can be spaced apart, that is, film layers of other materials can also be disposed between adjacent microporous polyurethane elastomer film layers. Of course, adjacent microporous polyurethane elastomer film layers can also be attached together. The arrangement can be selected according to actual usage requirements, and this application does not impose specific limitations on this.

[0045] The microporous polyurethane elastomer film can be made by adding inorganic hollow microspheres to a polyurethane elastomer. Specifically, it can be obtained by adding a certain amount of vulcanizing agent, inorganic hollow microspheres, and other compounding agents to a polyurethane elastomer and then cross-linking and curing it. In other words, the diaphragm of this application is a microporous polyurethane elastomer material containing polyurethane elastomer and inorganic hollow microspheres. The polyurethane elastomer acts as the substrate, and can be selected according to the performance requirements of the sound-generating device. After the inorganic hollow microspheres and polyurethane elastomer undergo a mixing process, the inorganic hollow microspheres, as micropore-forming materials, can be dispersed in the substrate to form a microporous structure on the substrate. Because inorganic hollow microspheres have a low density, adding them to the polyurethane elastomer can reduce the density of the diaphragm material, resulting in a low-density diaphragm material.

[0046] The mid-frequency range of the frequency response of a sound-generating device is the mass control region of the vibration system; the lower the vibration mass, the higher the mid-frequency sensitivity. This application, by incorporating inorganic hollow microspheres into a polyurethane elastomer, effectively reduces the vibration mass of the vibration system. Compared to conventional polyurethane foam diaphragms, the diaphragm of the sound-generating device in this application has a lower density, which reduces the vibration mass of the vibration system, thereby giving the sound-generating device higher mid-frequency sensitivity.

[0047] Inorganic hollow microspheres can be hollow glass microspheres, hollow ceramic microspheres, etc. Hollow glass microspheres are composed of inorganic materials such as silicon dioxide, alumina, zirconium oxide, magnesium oxide, and sodium silicate, along with an internally enclosed gas. The main component of the outer shell of hollow glass microspheres is borosilicate, which possesses characteristics such as high rigidity, good chemical stability, and a high melting point.

[0048] Specifically, because inorganic hollow microspheres inherently possess cavities, when added to polyurethane elastomers, these microspheres can integrate into the polyurethane elastomer, thus creating these cavities and forming micropores within the elastomer. The size of these micropores can be controlled by adjusting the particle size of the inorganic hollow microspheres. In other words, compared to conventional polyurethane foam materials (without added inorganic hollow microspheres), the foaming process is easier to control, resulting in more uniform cell structure and less susceptibility to external pressure and thermal effects, leading to more consistent diaphragm materials.

[0049] It should be noted that if only inorganic hollow microspheres are used as the micropore-forming material, the micropores in the microporous polyurethane elastomer film are formed by the cavities of the inorganic hollow microspheres themselves.

[0050] Furthermore, the average size of the micropores can be controlled within the range of 1μm to 60μm. For example, the average size of the micropores can be 1μm, 5μm, 10μm, 20μm, 30, 45μm, 50μm, or 60μm. Inorganic hollow microspheres of different sizes can be selected according to the different diaphragm thicknesses to ensure that the inorganic hollow microspheres are uniformly dispersed in the substrate.

[0051] Optionally, the average size of the micropores is 5μm to 45μm, preferably 5μm to 30μm. The pore size can be selected according to the matched diaphragm product. It is worth noting that the average pore size of the micropores should be smaller than the thickness of the microporous polyurethane elastomer film. When the pore size is less than 1μm, the density reduction of the microporous polyurethane elastomer film is not significant; when the pore size is greater than 80μm, the strength of the microporous polyurethane elastomer film decreases significantly, and problems such as collapse are prone to occur during use. The size of the diaphragm micropores in this application is mainly controlled by the size of the inorganic hollow microspheres.

[0052] Of course, for the microporous structure in polyurethane elastomers, microporous polyurethane elastomer materials can be prepared by modifying them with inorganic hollow microspheres, or by adding appropriate amounts of inorganic hollow microspheres and foaming agents (such as expanded microspheres) to the formulation to prepare micropores. Both methods can ensure the stability of the micropore size in the microporous polyurethane elastomer film.

[0053] The amount of inorganic hollow microspheres added accounts for 5 wt% to 50 wt% of the total raw materials used to prepare the microporous polyurethane elastomer film. As the amount of inorganic hollow microspheres added increases, the density of the microporous polyurethane elastomer film decreases. The desired diaphragm material performance can be obtained by controlling the amount of inorganic hollow microspheres added. The content of inorganic hollow microspheres can be any value between 5 wt% and 50 wt%, preferably 10 wt% to 40 wt%. For example, the content of inorganic hollow microspheres can be 5 wt%, 10 wt%, 15 wt%, 20 wt%, 30 wt%, 40 wt%, or 50 wt%.

[0054] It should be noted that, since the density of inorganic hollow microspheres is much lower than that of polyurethane rubber, the density of the microporous polyurethane elastomer film will decrease significantly as the amount of inorganic hollow microspheres added increases. Specifically, when the content of inorganic hollow microspheres is low (less than 5 wt%), it has little effect on the density of the diaphragm material, and the diaphragm still has a large mass. Furthermore, with the continuous increase in the amount of inorganic hollow microspheres added, the toughness of the elastomer body material (polyurethane elastomer) first increases and then decreases.

[0055] When the content of inorganic hollow microspheres is too high (greater than 50 wt%), the excessive mass proportion of inorganic hollow microspheres leads to a decrease in the adhesive content, an increase in the material modulus, and a decrease in the fracture strain. This results in a decrease in the toughness and an increase in the brittleness of the microporous polyurethane elastomer film material. Due to its excessively high mechanical strength, the maximum amplitude that the prepared diaphragm can achieve under the same driving force is reduced, thus decreasing the low-frequency sensitivity of the sound-generating device. Furthermore, the excessive addition of inorganic hollow microspheres significantly reduces the density of the microporous polyurethane elastomer film, resulting in lower elongation at break and strength of the prepared diaphragm, making the diaphragm prone to reliability problems such as collapse and rupture.

[0056] Therefore, by using inorganic hollow microspheres, which account for 5wt% to 50wt% of the total raw materials used to prepare the microporous polyurethane elastomer film, as the diaphragm material, the density and strength of the diaphragm can be simultaneously achieved, effectively ensuring the excellent mid-frequency and low-frequency performance of the diaphragm.

[0057] By controlling the amount of inorganic hollow microspheres added, the loss factor of the microporous polyurethane elastomer film at room temperature can be maintained within the range of 0.01 to 0.15. The damping of the diaphragm material must be moderate, meaning the diaphragm material must have appropriate absorption within it. The ideal vibration condition of the diaphragm in a sound-generating device is that the diaphragm should start immediately when the voice coil starts and stop immediately when no audio current flows through the voice coil. The former requires low diaphragm damping, while the latter requires high diaphragm damping. Therefore, balancing both aspects, the damping of the diaphragm material must be moderate to ensure good acoustic performance of the sound-generating device.

[0058] Due to the addition of inorganic hollow microspheres, they exhibit a relatively large size effect, increasing the heat generated by chain segment movement during diaphragm vibration. This allows for the dissipation of more energy during vibration, thus improving the material's damping. While increased diaphragm material damping helps resist abnormal vibrations during diaphragm vibration and reduces speaker distortion, excessive damping can lead to vibration hysteresis and reduced transient response. This results in a decrease in sound quality, causing a muffled sound. Preferably, the loss factor can be between 0.05 and 0.12.

[0059] Therefore, the diaphragm of the sound-generating device according to the embodiments of this application, made by adding inorganic hollow microspheres to a polyurethane elastomer to form a microporous polyurethane elastomer film layer, has uniform micropore distribution, stable size, and excellent diaphragm material stability. This not only reduces the density of the diaphragm and improves the mid-frequency sensitivity of the sound-generating device, but also allows the diaphragm material to have suitable damping by controlling the amount of inorganic hollow microspheres added, thus balancing the strength and transient resilience required during diaphragm vibration. Therefore, the sound-generating device using the diaphragm of this application has superior sound quality.

[0060] According to one embodiment of this application, the inorganic hollow microspheres have a particle size of 1 μm to 60 μm, and the distribution density of the inorganic hollow microspheres in the microporous polyurethane elastomer film is 0.35 g / cm³. 3 ~0.9g / cm 3 .

[0061] The pore size of the diaphragm in this application is mainly controlled by the size of the inorganic hollow microspheres. That is, by selecting inorganic hollow microspheres with a particle size of 1μm to 60μm, the average size of the micropores can be controlled within the range of 1μm to 60μm, preferably 5μm to 45μm, and more preferably 5μm to 30μm. A suitable particle size of the inorganic hollow microspheres not only facilitates their dispersion in the substrate but also appropriately reduces the density of the substrate, ensuring its mechanical properties.

[0062] Selecting inorganic hollow microspheres of different sizes based on varying diaphragm thickness ensures uniform dispersion of the microspheres within the substrate. Furthermore, as the size of the inorganic hollow microspheres decreases, their density tends to increase. To effectively reduce the diaphragm density, a distribution density of 0.35 g / cm³ was used for the inorganic hollow microspheres. 3 ~0.9g / cm 3 Preferably, the distribution density of the inorganic hollow microspheres can be 0.35 g / cm³. 3 ~0.8g / cm 3 .

[0063] In some specific embodiments of this application, the density of the microporous polyurethane elastomer film is 0.6 g / cm³. 3 ~1.15g / cm 3 .

[0064] In other words, by adding inorganic hollow microspheres to polyurethane elastomers to form a microporous polyurethane elastomer film, and by adjusting the amount of inorganic hollow microspheres added, the density of the microporous polyurethane elastomer film can be controlled at 0.6 g / cm³. 3 ~1.15g / cm 3 For example, the density of a microporous polyurethane elastomer film can be 0.6 g / cm³. 3 0.7g / cm 3 0.8g / cm 3 0.9g / cm 3 1g / cm 3 Or 1.15g / cm 3 .

[0065] The density of conventional polyurethane elastomer materials is 1.2 g / cm³. 3The introduction of micropores can effectively reduce the density of materials. However, excessively low material density is often accompanied by a loss of material strength. Although the larger the particle size of the added inorganic hollow microspheres, the lower the density of the microporous polyurethane elastomer film, if the micropore size is too large, the diaphragm material is prone to collapse and deformation during use, reducing the reliability of the diaphragm.

[0066] According to one embodiment of this application, the polyurethane elastomer is a compounded polyurethane elastomer.

[0067] In some specific embodiments of this application, the polyurethane elastomer is one or more of polyester polyurethane elastomers, polycarbonate polyurethane elastomers, and polyether ester polyurethane elastomers.

[0068] Specifically, the polyurethane elastomer can be selected from at least one of compounded polyurethane elastomers and cast polyurethane elastomers. Based on the controllability of diaphragm fabrication and the stability of the product, a compounded polyurethane elastomer is preferred.

[0069] Polyurethane elastomers can be composed of soft and hard segments. Based on the raw materials used in the soft segments, polyurethane elastomers can be classified into polyester-type, polyether ester-type, polyether-type, and polycarbonate-type. Because the diaphragm of a sound-generating device needs to meet the requirements of long-term high-temperature and high-humidity reliability and chemical resistance, one or more of polyester-type, polycarbonate-type, and polyether ester-type polyurethane elastomers are preferred.

[0070] According to one embodiment of this application, the tensile strength of the microporous polyurethane elastomer film is greater than 10 MPa and the elongation at break is greater than 300%.

[0071] In other words, by adding inorganic hollow microspheres to polyurethane elastomers to form microporous polyurethane elastomer films, and by adjusting the amount of inorganic hollow microspheres added, the tensile strength of the microporous polyurethane elastomer film can be greater than 10 MPa, and the elongation at break can be greater than 300%. The microporous polyurethane elastomer film has excellent mechanical properties, making the diaphragm product less prone to reliability issues such as collapse or rupture, further ensuring the stability of the sound-generating device.

[0072] According to one embodiment of this application, the micropore-forming material further includes a foaming agent, which is added to the polyurethane elastomer to form micropores.

[0073] In other words, inorganic hollow microspheres and foaming agents can be added simultaneously to the formulation of diaphragm materials to create micropores. By using foaming agents and inorganic hollow microspheres as the micropore-forming materials, it is possible to ensure that the micropores in the microporous polyurethane elastomer film are uniformly distributed and dimensionally stable. On the other hand, since the addition of inorganic hollow microspheres increases the modulus of the diaphragm, adding foaming agents (such as expanded microspheres) again can reduce the diaphragm density without increasing the modulus, thus balancing the diaphragm modulus and improving the sound production effect of the diaphragm.

[0074] Optionally, the thickness of the microporous polyurethane elastomer film can be 30μm to 200μm, preferably 40μm to 150μm. When the thickness of the microporous polyurethane elastomer film is less than 30μm, the stiffness of the microporous polyurethane elastomer material is insufficient, and polarization is prone to occur during diaphragm vibration, leading to distortion of the sound-generating device. When the thickness of the microporous polyurethane elastomer film is greater than 200μm, the diaphragm is too thick, occupying vibration space and easily causing rubbing and resulting in poor sound quality. Moreover, excessive diaphragm thickness will increase the weight of the diaphragm, thereby affecting the diaphragm's sound-generating sensitivity.

[0075] Furthermore, inorganic hollow microspheres have a certain reinforcing effect on polyurethane elastomer systems and can also block the absorption of chemicals. The microporous polyurethane elastomer material containing inorganic hollow microspheres provided in this application, when used as a diaphragm in a sound-generating device, not only meets the product's requirements for high sound quality, high loudness, high temperature resistance, and product stability, but also exhibits excellent performance in terms of chemical resistance (such as sweat, grease, and cosmetics). Compared to other types of diaphragm materials, its application in wearable sound-generating devices can achieve superior overall performance.

[0076] In addition to having a certain reinforcing effect on polyurethane elastomer systems and the effect of blocking chemical absorption, inorganic hollow microspheres can also reduce the mutual influence between polyurethane elastomer chain segments, thereby reducing the molding shrinkage rate.

[0077] In summary, the diaphragm of the sound-generating device according to the embodiments of this application, by controlling the selection of polyurethane elastomer and the amount of inorganic hollow microspheres added, yields a microporous polyurethane elastomer film layer that can simultaneously achieve the required strength and transient resilience during diaphragm vibration. Furthermore, the density and pore size of the microporous polyurethane elastomer film layer of this application are mainly determined by the size and content of the inorganic hollow microspheres, significantly reducing sensitivity to pressure and temperature during the preparation process. The process control is simple, and the resulting microporous polyurethane elastomer film layer exhibits uniform pores, excellent consistency, and good batch stability.

[0078] According to the second aspect of this application, the method for preparing the diaphragm of the sound-generating device includes: adding a vulcanizing agent, inorganic hollow microspheres, and other compounding agents to a polyurethane elastomer, and then mixing them to obtain a mixture. The mixture is placed on a diaphragm molding mold and hot-pressed to obtain the diaphragm.

[0079] In other words, the diaphragm of the sound-generating device of this application can be prepared by first preparing a compound and then molding the compound. Specifically, firstly, a certain amount of vulcanizing agent, inorganic hollow microspheres, and other compounding agents can be added to a polyurethane elastomer and then mixed to obtain a mixture. Then, an appropriate amount of the mixture is placed on a diaphragm molding mold and hot-pressed to obtain a diaphragm with the desired structure. The molding temperature can be 80℃~200℃, the molding time can be 50s~600s, and the molding pressure can be 1MPa~20MPa.

[0080] According to the third aspect of this application, the method for preparing the diaphragm of the sound-generating device includes: adding a vulcanizing agent and other compounding agents to a polyurethane elastomer, and then mixing them to obtain a mixture.

[0081] A mixture of inorganic hollow microspheres and a solvent is dissolved to obtain a slurry, with the solid content of the slurry controlled between 15% and 45%. The slurry is then coated to prepare a film. The film is placed on a diaphragm forming mold and hot-pressed to obtain a diaphragm.

[0082] In other words, the diaphragm of the sound-generating device of this application can also be prepared by first preparing a membrane material of uniform thickness, and then heating and curing the membrane material. Specifically, firstly, a certain amount of vulcanizing agent and other compounding agents are added to a polyurethane elastomer, and a mixture is obtained after mixing; then, the mixture and an appropriate amount of inorganic hollow microspheres are dissolved in a solvent to prepare a mixed slurry. Next, a film of a certain thickness is prepared from the mixed slurry by coating. Finally, a film of a suitable size is placed on a diaphragm forming mold, and the desired diaphragm structure is obtained after hot pressing. The forming temperature can be 80℃~200℃, the forming time can be 50s~600s, and the forming pressure can be 1MPa~20MPa.

[0083] Hot pressing is a molding method that uses heating and pressure to form materials, including compression molding, pneumatic molding, and infrared molding.

[0084] Furthermore, to ensure superior waterproofing of the sound-generating device, the diaphragm can be integrally molded with the dome, bonding the diaphragm ring to the dome using temperature and pressure during the hot-pressing process. Alternatively, after the diaphragm material is molded, it can be cut to the required size and assembled with the dome using adhesive. The dome can be the spherical top of the diaphragm.

[0085] The diaphragm material of this application is a microporous polyurethane elastomer material comprising polyurethane elastomer and inorganic hollow microspheres. The diaphragm can be prepared by first preparing a compound and then molding the compound. Alternatively, it can be prepared by first preparing a film material of uniform thickness and then heating and curing the film material. The microporous polyurethane elastomer prepared using this application exhibits significantly reduced sensitivity to pressure and temperature during the preparation process, as the material's density and micropore size are primarily determined by the size and content of the inorganic hollow microspheres. This simplifies process control, and the resulting microporous polyurethane elastomer film layer has uniform pore size, excellent consistency, and good batch stability.

[0086] Of course, to ensure the dimensional stability of the micropores in the diaphragm, the polyurethane elastomer can be modified with inorganic hollow microspheres to prepare microporous polyurethane elastomer materials. Alternatively, an appropriate amount of foaming agent (such as expanded microspheres) can be added to the formulation to prepare the micropores. Compared to conventional polyurethane foam materials, the foaming process is easier to control after adding inorganic hollow microspheres to the polyurethane system, the pores are relatively uniform, and they are less affected by external pressure, thermal effects, and other factors, resulting in a more consistent diaphragm material. Moreover, since the addition of inorganic hollow microspheres increases the modulus of the diaphragm, adding another foaming agent (such as expanded microspheres) can reduce the diaphragm density without increasing the modulus, thus balancing the diaphragm modulus and improving the sound production effect. Therefore, the diaphragm material prepared by controlling the selection of polyurethane elastomer and the amount of inorganic hollow microspheres in this application can effectively balance the strength and transient resilience required during vibration. Therefore, better sound quality can be obtained.

[0087] The method for preparing the diaphragm of the sound-generating device according to the embodiments of this application is not only simple in manufacturing process and easier to control in foaming process, resulting in relatively uniform foam cells, but also produces a diaphragm with good strength and transient resilience, enabling the sound-generating device to have good acoustic performance.

[0088] According to one embodiment of this application, the hot pressing temperature is 80℃~200℃, the pressing time is 50s~600s, and the pressing pressure is 1MPa~20MPa. By controlling the hot pressing temperature, pressing time, and pressing pressure within a certain range, the quality of the microporous polyurethane elastomer film can be guaranteed.

[0089] In some specific embodiments of this application, the shrinkage rate before and after diaphragm molding is 1.0% to 2.5%.

[0090] It should be noted that during the vulcanization process of rubber materials, after the finished product is demolded, its geometric dimensions will shrink to varying degrees. This phenomenon is commonly referred to as shrinkage in the industry. The ratio (expressed as a percentage) between the mold size and the size difference of the same part of the finished product after vulcanization is called the molding shrinkage rate.

[0091] Polyurethane elastomer materials modified with inorganic hollow microspheres exhibit lower molding shrinkage during curing due to the reduced interaction between polyurethane elastomer molecular chains caused by the presence of these microspheres. Based on the size and amount of the inorganic hollow microspheres used in this application, the molding shrinkage rate can be controlled within 1.0% to 2.5%. In other words, in addition to providing reinforcement and preventing chemical absorption in the polyurethane elastomer system, the inorganic hollow microspheres also reduce the interaction between polyurethane elastomer chain segments, thereby reducing molding shrinkage, effectively ensuring product dimensions, and improving product yield.

[0092] According to one embodiment of this application, the amount of vulcanizing agent added accounts for 0.1wt% to 10wt% of the total amount of the mixture, and the vulcanizing agent is one or more of peroxide vulcanizing agents and sulfur vulcanizing agents.

[0093] According to one embodiment of this application, other compounding agents include at least one of reinforcing fillers, vulcanizing accelerators, plasticizers, anti-hydrolysis agents, antioxidants, foaming agents, and compatibilizers.

[0094] Specifically, the following compounds are added in amounts calculated based on 100 parts by weight of raw polyurethane elastomer.

[0095] The vulcanizing agent is selected from one or more peroxide-based and sulfur-based vulcanizing agents, and the amount added is 0.1 to 10 parts by weight. Optionally, the vulcanizing agent can be one or more of dicumyl peroxide (DCP), 1,1-di-tert-butylperoxy-3,3,5-trimethylcyclohexane (3M), di-tert-butyl and peroxide, 2,5-dimethyl-2,5-(di-tert-butylperoxy)hexane, bis-tert-butylperoxyisopropylbenzene (BIBP), benzoyl peroxide (BP), 2,4-dichlorobenzoyl peroxide (DCBP), tert-butyl perbenzoate and sulfur.

[0096] The reinforcing filler is one or more of the following: carbon black, silica, clay, talc, wollastonite, mica powder, asbestos, sepiolite, silica-alumina carbon black, calcium carbonate, magnesium carbonate, dolomite, barium sulfate, zinc sulfide, aluminum powder, graphite, titanium dioxide, zinc barium white, phenolic resin, petroleum resin, and styrene resin, and the amount added is 0 to 30 parts by weight.

[0097] The vulcanizing accelerator can be a thiazole (M, DM), a sulfenamide (CZ, NOBS, DZ), a thiuram (TMTD, TMTM), a thiourea (NA-22), a dithiocarbamate (ZDMC, ZDC), an aldehyde amine (H), an arc (D), a xanthate (ZIX), a triallyl isocyanate (TAIC), a triallyl cyanurate (TAC), or N,N-m-m-mono-bismaleimide (HVA-2), with an addition amount of 0 to 5 parts by weight.

[0098] Plasticizers include alkanes, cycloalkanes, aromatics, tri-oil, petrolatum, paraffin wax, coumarone resin, coal tar, coal pitch, pine tar, rosin oil, tall oil, ointments, glycerin, castor oil, soybean oil, oleic acid, phthalates, fatty acid diesters, fatty acids, phosphate esters, polyesters, epoxy resins, chlorine-containing resins, octyl phthalate (DOP), diisodecyl phthalate (DIDP), dibutyl phthalate (DBP), and dioctyl adipate (D...). The plasticizer comprises one or more of the following: OA), dioctyl azelate (DOZ), dibutyl sebate (DBS), dioctyl sebate (DOS), oleic acid ester, castor oil, pentaerythritol fatty acid ester, citrate ester, tricresyl phthalate (TCP), tricresyl phthalate (TOP), sebacic acid-based polyester plasticizer, adipic acid-based polyester plasticizer, phthalic acid-based polyester plasticizer, epoxidized soybean oil, and epoxidized castor oil, wherein the amount of plasticizer is 0 to 25 parts by weight.

[0099] The anti-hydrolysis agent can be carbodiimide, and the dosage is 0 to 5 parts by weight.

[0100] The antioxidant may be at least one of the following: antioxidant 1010, antioxidant 2, antioxidant 6, antioxidant 4, antioxidant 1076, antioxidant 168, antioxidant RD, antioxidant AW, antioxidant DD, antioxidant BLE, antioxidant 4010, 4010NA, 4020, 4030, 4040, antioxidant DNP, antioxidant H, antioxidant A, antioxidant D, antioxidant SP, antioxidant 264, antioxidant 2246, antioxidant 2246-S, antioxidant NBC, and antioxidant MB, etc., and the dosage is 0 to 5 parts by weight.

[0101] The foaming agent includes at least one of foamed polymer microspheres and other foaming agents, which are at least one of azo compounds, sulfonyl hydrazides, nitrosamines, carbonates, and fluorocarbons. The amount of other foaming agents used is 0-5 parts by weight, and the amount of foamed polymer microspheres added is 0-20 parts by weight. To increase the compatibility between the inorganic hollow microspheres and the polyurethane elastomer matrix, the surface of the inorganic hollow microspheres can be appropriately modified, or an appropriate amount of compatibilizer (such as a silane coupling agent) can be added to the formulation.

[0102] It should be noted that the diaphragm provided in this application can be used to construct any sound-generating device, such as the following typical sound-generating device: including a vibration system and a magnetic circuit system that cooperates with the vibration system. The vibration system includes a diaphragm and a voice coil attached to one side of the diaphragm. When the sound-generating device is working, after the voice coil is energized, under the action of the magnetic field force of the magnetic circuit system, the voice coil can vibrate up and down to drive the diaphragm to vibrate, and sound can be generated when the diaphragm vibrates.

[0103] A sound-generating device according to a fourth aspect embodiment of this application includes a vibration system and a magnetic circuit system cooperating with the vibration system. The vibration system includes a diaphragm and a voice coil coupled to one side of the diaphragm. The magnetic circuit system drives the voice coil to vibrate, thereby causing the diaphragm to produce sound. The diaphragm is the diaphragm described in the above embodiment. Specifically, when the sound-generating device is working, after the voice coil is energized, under the action of the magnetic field force of the magnetic circuit system, the voice coil can vibrate up and down to drive the diaphragm to vibrate, and sound can be produced when the diaphragm vibrates.

[0104] like Figure 3 and Figure 4 As shown, the sound-generating device includes a diaphragm 15 prepared according to the above embodiments of this application. The diaphragm 15 may consist of a folded ring portion 151 and a dome portion 152. A microporous polyurethane elastomer film layer may be applied to the folded ring portion 151 of the diaphragm. Those skilled in the art can make corresponding adjustments according to actual product requirements, such as the folded ring portion 151 protruding towards the voice coil 11, the dome portion 152 being located on the lower surface of the folded ring portion 151, and adding a centering support plate to the vibration system.

[0105] like Figure 5 and Figure 6 As shown, the sound-generating device 100 according to the fifth aspect embodiment of this application includes a housing 10 and a magnetic circuit system 14 and a vibration system disposed within the housing 10. The vibration system includes a voice coil 11, a first diaphragm 12 and a second diaphragm 13. The top of the voice coil 11 is connected to the first diaphragm 12. The magnetic circuit system 14 drives the voice coil 11 to vibrate so as to drive the first diaphragm 12 to generate sound. The two ends of the second diaphragm 13 are respectively connected to the bottom of the housing 10 and the bottom of the voice coil 11. The second diaphragm 13 is the diaphragm of the above embodiment.

[0106] In other words, the sound-generating device 100 according to the embodiments of this application may further include two diaphragms prepared by the above embodiments of this application, namely a first diaphragm 12 and a second diaphragm 13. The first diaphragm 12 can be used to vibrate and generate sound, and the second diaphragm 13 can be used to balance the vibration of the voice coil 11. Specifically, when the sound-generating device 100 is working, after the voice coil 11 is energized, under the action of the magnetic field force of the magnetic circuit system 14, the voice coil 11 can vibrate up and down to drive the first diaphragm 12 to vibrate, and the first diaphragm 12 can generate sound when it vibrates. The second diaphragm 13 can also vibrate up and down with the voice coil 11. Since the two ends of the second diaphragm 13 are respectively connected to the housing 10 and the bottom of the voice coil 11, the second diaphragm 13 can balance the vibration of the voice coil 11 and prevent the voice coil 11 from being polarized, thereby improving the sound generation effect of the sound-generating device 100.

[0107] It should be noted that the first diaphragm 12 and the second diaphragm 13 can both adopt the diaphragm of the above embodiments of this application, or one of the first diaphragm 12 and the second diaphragm 13 can adopt the diaphragm of the above embodiments of this application. This application does not make any specific restrictions in this regard.

[0108] The diaphragm of the sound-generating device of this application will be specifically described below with reference to specific embodiments.

[0109] Examples 1 to 5

[0110] Examples 1 through 5 all used polyester-type polyurethane compound with a hardness of 50A.

[0111] The formula is as follows: 100 parts by weight of raw rubber, 5 parts by weight of adipic acid polyester plasticizer, 1 part by weight of vulcanizing accelerator (tracene isocyanate), 10 parts by weight of reinforcing filler (carbon black), 3 parts by weight of hydrolysis inhibitor (carbodiimide), 2 parts by weight of antioxidant (antioxidant 1010), and 4 parts by weight of vulcanizing agent (dicumyl peroxide). After mixing evenly, a certain amount of hollow glass microspheres (3M K46 model) are added using a two-roll mill to obtain the compound. The specific amounts of hollow glass microspheres added in Examples 1 to 5 are shown in Table 1.

[0112] Furthermore, the compound rubbers of Examples 1 to 5 were subjected to flat vulcanization. An appropriate amount of the compound rubber was placed in a square mold (100 mm long, 100 mm wide, and 200 μm thick), and the film (diaphragm material) was made at 170°C.

[0113] Comparative Example 1

[0114] The polyester-type polyurethane compound with a hardness of 50A was used. Except for the absence of hollow glass microspheres, the formulation and manufacturing method were the same as those in Examples 1 to 5.

[0115] The following performance tests were performed on the films of Examples 1 to 5 and Comparative Example 1:

[0116] Test parameters: density, tensile strength, elongation at break, molding shrinkage, and loss factor.

[0117] (1) Molding shrinkage rate: Shrinkage rate = (Mold size - Film size) / Mold size;

[0118] (2) Tensile strength / elongation at break: Tensile mode test was performed using a tensile testing machine in accordance with ASTM D882 standard;

[0119] (3) Loss factor: DMA device, stretching mode, vibration frequency 1Hz, temperature rise 3℃ / min.

[0120] Table 1 shows the performance test results of the films of Examples 1 to 5 and Comparative Example 1, demonstrating the effect of the amount of hollow glass microspheres added on the density, tensile strength, elongation at break, molding shrinkage and loss factor of the diaphragm material.

[0121] Table 1

[0122]

[0123] As shown in Table 1, the content of hollow glass microspheres in Examples 1 to 5 increases sequentially. With the increase of hollow glass microspheres, the density of the diaphragm material decreases, and the tensile strength increases with the increase of hollow glass microspheres, but the elongation at break initially increases and then decreases. This is because the addition of hollow glass microspheres can provide a certain reinforcing effect on the microporous polyurethane elastomer; however, excessive addition of hollow glass microspheres will lead to a decrease in the toughness of the material itself, thus manifesting as an initial increase and subsequent decrease in elongation at break.

[0124] Furthermore, the effect of hollow glass microspheres on the shrinkage rate of microporous polyurethane elastomers is similar to the effect of fillers on the shrinkage rate of rubber. As the amount of hollow glass microspheres added increases, the shrinkage rate of the diaphragm material decreases. Moreover, hollow glass microspheres have a relatively large size effect, which makes the reduction in the shrinkage rate of the microporous polyurethane elastomer film more significant.

[0125] The presence of hollow glass microspheres increases the resistance to the movement of polyurethane molecular chains, thereby improving the damping of the diaphragm material. As shown in Table 1, the loss factor of the diaphragm material increases significantly with increasing amounts of hollow glass microspheres.

[0126] In addition, such as Figure 2 The image shown is a cross-sectional view of the microporous polyurethane elastomer film obtained after vulcanization in Example 3. It can be seen that the hollow glass microspheres can be uniformly distributed in the polyurethane elastomer matrix, thereby ensuring that the diaphragm material obtains good performance.

[0127] It should be noted that hollow glass microspheres are a type of inorganic hollow microspheres. In Examples 1 to 5 and Comparative Example 1, hollow glass microspheres or other inorganic hollow microspheres were used, which can all demonstrate the role of inorganic hollow microspheres in the material.

[0128] Acoustic performance testing

[0129] The diaphragms were prepared according to the formulations of Example 3 and Comparative Example 1, and the acoustic performance of the products was evaluated.

[0130] Example 3, Comparative Example 1

[0131] The preparation method involves preparing the compound rubber according to the formulations of Example 3 and Comparative Example 1, placing the compound rubber on a diaphragm molding mold, and hot-pressing it at a molding temperature of 180°C and a molding pressure of 10 MPa for approximately 200 seconds. The mold is then removed, and the molded diaphragm material is cut to obtain the desired diaphragm material (approximately 90 μm thick). The diaphragm material is then assembled with the dome and housing using adhesive to obtain the final speaker product.

[0132] Comparative Example 2

[0133] To further compare the diaphragm material prepared according to the scheme of this application with the thermoplastic polyurethane elastomer (TPU) diaphragm commonly used in the industry,

[0134] Meanwhile, Comparative Example 2 (diaphragm material is TPU (thermoplastic polyurethane elastomer rubber) material with a hardness of 90A and a thickness of 35um) was used to evaluate the product performance.

[0135] It should be noted that Comparative Example 1 and Examples 1 to 5 all used polyester-type polyurethane compound, which underwent a crosslinking reaction to form a network structure. Comparative Example 2, however, used ordinary thermoplastic polyurethane elastomer rubber without further treatment.

[0136] The assembled loudspeakers of Example 3, Comparative Example 1, and Comparative Example 2 were subjected to sound testing in an anechoic chamber, and their frequency response curves (SPL) were obtained. Figure 1 As shown, the vertical axis SPL represents the sensitivity level. The higher the value, the higher the sensitivity, and the louder the product will be.

[0137] like Figure 1 As shown, the curve of Example 3 is above that of Comparative Example 1 and Comparative Example 2. That is to say, under the premise that the product F0 is similar, the product with a diaphragm made of microporous polyurethane elastomer with added hollow glass microspheres has better mid-frequency sensitivity, which means that the sound-generating device has greater loudness.

[0138] It should be noted that Comparative Example 1 is a non-foamed compounded polyurethane rubber with a hardness of 50A. Compared with Comparative Example 2 (hardness 90A), in order to obtain the required stiffness, the thickness of Comparative Example 1 was increased by more than 2 times, which led to a decrease in product sensitivity.

[0139] Furthermore, wearable electronic products inevitably come into contact with chemicals during use, such as cosmetics, human sweat, and oils. Reliability tests for chemicals were conducted on 100 products from Comparative Example 1, Comparative Example 2, and Example 3, respectively. Oils were used as the chemical in the tests; the oils were applied to the product surface and left for 48 hours before testing.

[0140] Table 2

[0141]

[0142] As shown in Table 2, the test results showed that 78 products in Comparative Example 2 (TPU diaphragm) experienced diaphragm cracking, while the products in Comparative Example 1 and Example 3 showed no delamination after the chemical test. Acoustic performance testing of the products that did not delaminate revealed a decrease in the F0 of Comparative Example 2 (TPU diaphragm). This may be because the grease is a low molecular weight compound, and during storage, it can enter the TPU molecular chains, playing a certain plasticizing role, leading to a decrease in the material modulus and thus a decrease in the product's F0.

[0143] The changes in F0 in Comparative Example 1 and Example 3 were both very small, with Example 3 showing better results, exhibiting zero change in F0 after the experiment. This may be because the diaphragm materials in Comparative Example 1 and Example 3 are both polyurethane rubber matrices, which are network cross-linked polymers. Although grease can partially penetrate, the penetration amount is significantly reduced due to the presence of the network structure. Furthermore, the presence of the cross-linked structure restricts the movement of molecular chain segments, also reducing the impact of grease on the diaphragm materials of Example 3 and Comparative Example 1. Further, the diaphragm material in Example 3 contained hollow glass microspheres. The presence of these inorganic hollow microspheres further improved the product's performance in blocking chemicals, thus the product of Example 3 was almost unaffected by chemicals.

[0144] Therefore, inorganic hollow microspheres have a certain reinforcing effect on polyurethane elastomer systems and can also block the absorption of chemicals. The microporous polyurethane elastomer material containing inorganic hollow microspheres provided in this application, when used as a diaphragm in a sound-generating device, not only meets the product's requirements for high sound quality, high loudness, high temperature resistance, and product stability, but also exhibits excellent performance in terms of chemical resistance (such as sweat, grease, and cosmetics). Compared to other types of diaphragm materials, the diaphragm of this application, when applied to wearable sound-generating devices, enables the device to have better acoustic performance.

[0145] While specific embodiments of this application have been described in detail by way of examples, those skilled in the art should understand that the above examples are for illustrative purposes only and are not intended to limit the scope of this application. Those skilled in the art should understand that modifications can be made to the above embodiments without departing from the scope and spirit of this application. The scope of this application is defined by the appended claims.

Claims

1. A diaphragm for a sound-generating device, characterized in that, The diaphragm is composed of a folded ring and a spherical top. The folded ring includes at least one layer of microporous polyurethane elastomer film. The microporous polyurethane elastomer film includes a polyurethane elastomer and a micropore-forming material. The microporous polyurethane elastomer film has micropores. The microporous forming material comprises inorganic hollow microspheres, the content of which is 5wt% to 50wt% of the total amount of the microporous polyurethane elastomer film. The average pore size of the microspheres is 1μm to 60μm, and the loss factor of the microporous polyurethane elastomer film at room temperature is ≤0.

15. The particle size of the inorganic hollow microspheres is 1μm to 60μm, and the distribution density of the inorganic hollow microspheres in the microporous polyurethane elastomer film is 0.35g / cm³. 3 ~0.9g / cm 3 .

2. The diaphragm of the sound-generating device according to claim 1, characterized in that, The density of the microporous polyurethane elastomer film is 0.6 g / cm³. 3 ~1.15g / cm 3 .

3. The diaphragm of the sound-generating device according to claim 1, characterized in that, The polyurethane elastomer is a compounded polyurethane elastomer.

4. The diaphragm of the sound-generating device according to claim 3, characterized in that, The polyurethane elastomer is one or more of polyester polyurethane elastomers, polycarbonate polyurethane elastomers, and polyether ester polyurethane elastomers.

5. The diaphragm of the sound-generating device according to claim 1, characterized in that, The microporous polyurethane elastomer film has a tensile strength greater than 10 MPa and an elongation at break greater than 300%.

6. The diaphragm of the sound-generating device according to claim 1, characterized in that, The micropore-forming material further includes a foaming agent, which is added to the polyurethane elastomer to form the micropores.

7. A method for preparing the diaphragm of the sound-generating device according to any one of claims 1-6, characterized in that, The diaphragm comprises a folded ring portion and a spherical top portion. The preparation method is used to prepare the folded ring portion of the diaphragm, and the preparation method includes: A mixture is obtained by adding a vulcanizing agent, inorganic hollow microspheres and other compounding agents to a polyurethane elastomer and then mixing it. The mixture is placed on a diaphragm forming mold and hot-pressed to obtain the diaphragm.

8. The method for preparing the diaphragm of the sound-generating device according to claim 7, characterized in that, The hot pressing process is performed at a temperature of 80℃ to 200℃, a molding time of 50s to 600s, and a molding pressure of 1MPa to 20MPa.

9. The method for preparing the diaphragm of the sound-generating device according to claim 7, characterized in that, The shrinkage rate of the diaphragm before and after molding is 1.0% to 2.5%.

10. The method for preparing the diaphragm of the sound-generating device according to claim 7, characterized in that, The amount of the vulcanizing agent added accounts for 0.1wt% to 10wt% of the total amount of the mixture, and the vulcanizing agent is one or more of peroxide vulcanizing agents and sulfur vulcanizing agents.

11. The method for preparing the diaphragm of the sound-generating device according to claim 7, characterized in that, The other compounding agents include at least one of reinforcing fillers, vulcanizing accelerators, plasticizers, anti-hydrolysis agents, antioxidants, foaming agents, and compatibilizers.

12. A method for preparing the diaphragm of the sound-generating device according to any one of claims 1-6, characterized in that, The diaphragm comprises a folded ring portion and a spherical top portion. The preparation method is used to prepare the folded ring portion of the diaphragm, and the preparation method includes: A mixture is obtained by adding vulcanizing agents and other compounding agents to a polyurethane elastomer and then mixing it. The mixture and inorganic hollow microspheres are dissolved in a solvent to obtain a mixed slurry, and the solid content of the mixed slurry is controlled at 15% to 45%. The mixed slurry is coated to prepare a thin film; The diaphragm is obtained by placing the film on a diaphragm forming mold and hot-pressing it.

13. The method for preparing the diaphragm of the sound-generating device according to claim 12, characterized in that, The hot pressing process is performed at a temperature of 80℃ to 200℃, a molding time of 50s to 600s, and a molding pressure of 1MPa to 20MPa.

14. The method for preparing the diaphragm of the sound-generating device according to claim 12, characterized in that, The shrinkage rate of the diaphragm before and after molding is 1.0% to 2.5%.

15. The method for preparing the diaphragm of the sound-generating device according to claim 12, characterized in that, The amount of the vulcanizing agent added accounts for 0.1wt% to 10wt% of the total amount of the mixture, and the vulcanizing agent is one or more of peroxide vulcanizing agents and sulfur vulcanizing agents.

16. The method for preparing the diaphragm of the sound-generating device according to claim 12, characterized in that, The other compounding agents include at least one of reinforcing fillers, vulcanizing accelerators, plasticizers, anti-hydrolysis agents, antioxidants, foaming agents, and compatibilizers.

17. A sound-generating device, characterized in that, The device includes a vibration system and a magnetic circuit system that cooperates with the vibration system. The vibration system includes a diaphragm and a voice coil coupled to one side of the diaphragm. The magnetic circuit system drives the voice coil to vibrate so as to cause the diaphragm to produce sound. The diaphragm is the diaphragm according to any one of claims 1-6.

18. A sound-generating device, characterized in that, The device includes a housing and a magnetic circuit system and a vibration system disposed within the housing. The vibration system includes a voice coil, a first diaphragm, and a second diaphragm. The top of the voice coil is connected to the first diaphragm. The magnetic circuit system drives the voice coil to vibrate so as to cause the first diaphragm to produce sound. The two ends of the second diaphragm are respectively connected to the bottom of the housing and the bottom of the voice coil. The second diaphragm is the diaphragm according to any one of claims 1-6.

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