Diaphragm of sound-generating device and sound-generating device

Abstract

The present application discloses a diaphragm of a sound-generating device and a sound-generating device. The diaphragm includes at least one modified nitrile rubber membrane layer. The modified nitrile rubber membrane layer is prepared by mixing inorganic hollow microspheres, additives, and a polymer of acrylonitrile and butadiene monomers to form a mixed rubber, followed by a cross-linking reaction. The diameter of the inorganic hollow microspheres is 10 μm to 100 μm, and the distribution density of the inorganic hollow microspheres in the modified nitrile rubber membrane layer is 0.15 g / cm 3 ~0.9g / cm 3 , the specific surface area of ​​the inorganic hollow microspheres is ≥0.9, and the loss factor of the modified nitrile rubber film layer at room temperature is >0.13. The present application can effectively reduce the density of the diaphragm by adding inorganic hollow microspheres to the polymer of acrylonitrile and butadiene monomers. Moreover, by controlling the diameter of the inorganic hollow microspheres and their distribution density in the modified nitrile rubber film layer, the specific surface area of ​​the inorganic hollow microspheres can be made ≥0.9, thereby improving the bonding strength between the inorganic hollow microspheres and the polymer, thereby improving the structural strength of the diaphragm.

Description

Technical Field

[0001] The present application relates to the field of electroacoustic technology, and more specifically, to a diaphragm of a sound-generating device and a sound-generating device using the diaphragm. Background Art

[0002] With the rapid development of the 5G era, electroacoustic devices are gradually moving towards lighter weight, smarter operation, higher power, and higher frequency performance. These devices often require the use of rubber diaphragms. While rubber diaphragms offer excellent damping, compliance, and fatigue resistance, they are relatively heavy, increasing the mass of the vibration system and reducing speaker sensitivity. Furthermore, rubber diaphragms are expensive, making them difficult to manufacture.

[0003] In addition, when the amplitude of the currently available rubber diaphragm is relatively large, the strength and damping performance of the diaphragm are difficult to meet the usage requirements, thereby affecting the sound effect of the sound-generating device. Summary of the Invention

[0004] One object of the present application is to provide a diaphragm for a sound-generating device.

[0005] Another object of the present application is to provide a sound-generating device composed of the above-mentioned diaphragm.

[0006] In order to achieve the above objectives, this application provides the following technical solutions.

[0007] According to the diaphragm of the sound-emitting device of the first embodiment of the present application, the diaphragm includes at least one modified nitrile rubber membrane layer, which is prepared by mixing inorganic hollow microspheres, additives, and a polymer of acrylonitrile and butadiene monomers to form a mixed rubber and then undergoing a cross-linking reaction, wherein the diameter of the inorganic hollow microspheres is 10 μm to 100 μm, and the distribution density of the inorganic hollow microspheres in the modified nitrile rubber membrane layer is 0.15 g / cm 3 ~0.9g / cm 3 The specific surface area of ​​the inorganic hollow microspheres is ≥0.9, and the loss factor of the modified nitrile rubber film layer at room temperature is >0.13.

[0008] According to some embodiments of the present application, after the modified nitrile rubber film layer is aged in hot air at 100° C. for 168 hours, the tensile strength of the modified nitrile rubber film layer decreases by ≤45%, and the elongation at break decreases by ≤70%.

[0009] According to some embodiments of the present application, the tensile strength of the modified nitrile rubber film layer when broken is 2 MPa to 45 MPa.

[0010] According to some embodiments of the present application, the compressive strength of the inorganic hollow microspheres is ≥10 MPa.

[0011] According to some embodiments of the present application, the content of the inorganic hollow microspheres accounts for 5 wt % to 45 wt % of the total amount of the rubber mix.

[0012] According to some embodiments of the present application, the room temperature storage modulus of the modified nitrile rubber film layer is 0.5 MPa to 40 MPa.

[0013] According to some embodiments of the present application, the tear strength of the modified nitrile rubber film layer is 15 N / mm to 100 N / mm.

[0014] According to some embodiments of the present application, the additives include a cross-linking agent, a reinforcing agent and an antioxidant, the cross-linking agent is at least one of a metal oxide, a metal peroxide, an organic oxide and an organic peroxide system; the reinforcing agent is at least one of carbon black, white carbon black, graphene oxide, montmorillonite, talc, clay, mica powder, feldspar powder, sodium alginate, magnetic powder, and diatomaceous earth; the antioxidant is at least one of antioxidant N-445, antioxidant 246, antioxidant 4010, antioxidant SP, antioxidant RD, antioxidant ODA, antioxidant OD and antioxidant WH-02.

[0015] According to some embodiments of the present application, the content of the crosslinking agent accounts for 0.5wt% to 6wt% of the rubber mix, the content of the reinforcing agent accounts for 5wt% to 60wt% of the rubber mix, and the content of the antioxidant accounts for 0.1wt% to 5.7wt% of the rubber mix.

[0016] According to some embodiments of the present application, the density of the modified nitrile rubber film layer is 0.5 g / cm 3 ~1.1g / cm 3 .

[0017] According to some embodiments of the present application, the diaphragm is a single-layer structure, and the diaphragm is composed of a layer of the modified nitrile rubber membrane layer.

[0018] According to some embodiments of the present application, the diaphragm is a composite layer structure, and the diaphragm further includes a membrane layer made of at least one of a thermoplastic elastomer, an engineering plastic, and a thermosetting elastomer.

[0019] According to the second aspect of the embodiment of the present application, the sound-producing device includes a vibration system and a magnetic circuit system coordinated 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 to drive the diaphragm to produce sound, and the diaphragm is the diaphragm according to the above-mentioned embodiment of the present application.

[0020] According to the third aspect of the present application, the sound-producing device includes a shell and a magnetic circuit system and a vibration system arranged in the shell. 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 to drive the first diaphragm to produce sound. The two ends of the second diaphragm are respectively connected to the shell and the bottom of the voice coil. The second diaphragm is the diaphragm according to the above-mentioned embodiment of the present application.

[0021] According to the diaphragm of the sound-generating device of the embodiment of the present application, the modified nitrile rubber membrane layer is prepared by cross-linking a modified nitrile rubber membrane layer formed by mixing inorganic hollow microspheres, additives, and a polymer of acrylonitrile and butadiene monomers to form a rubber mixture, thereby reducing the density of the modified nitrile rubber membrane layer and reducing the weight of the diaphragm, thereby improving the sound sensitivity of the diaphragm. Moreover, by controlling the diameter of the inorganic hollow microspheres and their distribution density in the modified nitrile rubber membrane layer, the specific surface area of ​​the inorganic hollow microspheres can be made ≥0.9, thereby improving the bonding strength between the inorganic hollow microspheres and the polymer, thereby improving the structural strength of the diaphragm, and effectively improving the tensile strength and damping performance of the diaphragm.

[0022] Other features and advantages of the present application will become apparent from the following detailed description of exemplary embodiments of the present application with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate embodiments of the application and, together with the description, serve to explain the principles of the application.

[0024] Figure 1 The damping curves of the diaphragm of the sound-generating device according to the embodiment of the present application after vulcanization of the inorganic hollow microspheres filled with rubber of different diameters are shown;

[0025] Figure 2 The damping curves of the diaphragm of the sound-generating device according to the embodiment of the present application after vulcanization of the rubber filled with inorganic hollow microspheres at different addition amounts are shown;

[0026] Figure 3 1 is a harmonic distortion test curve of the diaphragm of the sound-generating device according to the embodiment of the present application and a conventional diaphragm before and after high temperature;

[0027] Figure 4 Schematic diagram of the overall structure of the sound-generating device according to an embodiment of the present application;

[0028] Figure 5 is a schematic diagram of a partial structure of a sound-generating device according to an embodiment of the present application;

[0029] Figure 6 is a cross-sectional view of a sound-generating device according to an embodiment of the present application;

[0030] Figure 7 1 is an exploded view of a sound-generating device according to an embodiment of the present application.

[0031] Reference numerals

[0032] Sound-generating device 100;

[0033] Housing 10; voice coil 11; first diaphragm 12; second diaphragm 13; magnetic circuit system 14;

[0034] Diaphragm 15 ; surround 151 ; dome 152 . DETAILED DESCRIPTION

[0035] 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 arrangements of components and steps, numerical expressions and numerical values ​​set forth in these embodiments do not limit the scope of the present application.

[0036] The following description of at least one exemplary embodiment is merely illustrative in nature and is in no way intended to limit the present disclosure, its application, or uses.

[0037] Technologies, methods, and equipment known to ordinary technicians in the relevant art may not be discussed in detail, but where appropriate, the technologies, methods, and equipment should be considered part of the specification.

[0038] In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not limiting. Therefore, other examples of the exemplary embodiments may have different values.

[0039] It should be noted that like reference numerals and letters refer to like items in the following figures, and therefore, once an item is defined in one figure, it need not be further discussed in subsequent figures.

[0040] The diaphragm of the sound-emitting device according to the embodiment of the present application is described in detail below with reference to the accompanying drawings.

[0041] According to the diaphragm of the sound-emitting device of the embodiment of the present application, the diaphragm includes at least one modified nitrile rubber membrane layer, which is prepared by kneading inorganic hollow microspheres, additives, and a polymer of acrylonitrile and butadiene monomers to form a mixed rubber and then undergoing a cross-linking reaction, wherein the diameter of the inorganic hollow microspheres is 10 μm to 100 μm, and the distribution density of the inorganic hollow microspheres in the modified nitrile rubber membrane layer is 0.15 g / cm 3 ~0.9g / cm 3 The specific surface area of ​​the inorganic hollow microspheres is ≥0.9, and the loss factor of the modified nitrile rubber film layer at room temperature is >0.13.

[0042] According to the embodiment of the present application, the diaphragm of the sound-emitting device can be composed of at least one layer of modified nitrile rubber membrane layer. Specifically, the diaphragm in the present application can be a single-layer structure or a multi-layer composite structure. When the diaphragm is a single-layer structure, the diaphragm is made of a layer of modified nitrile rubber membrane layer of the present application. When the diaphragm is a multi-layer composite structure, the diaphragm includes at least one layer of modified nitrile rubber membrane layer, and the modified nitrile rubber membrane layer in the diaphragm is composited with membrane layers of other materials in the multi-layer composite structure. Optionally, when the diaphragm contains multiple layers of modified nitrile rubber membrane layers, the two adjacent layers of modified nitrile rubber membrane layers can be spaced apart or fitted together, and the setting can be selected according to actual use requirements, and the present application does not impose specific restrictions on this. When the two adjacent layers of modified nitrile rubber membrane layers are spaced apart, a membrane layer of other materials can also be set between the two adjacent layers of modified nitrile rubber membrane layers, and of course the two adjacent layers of modified nitrile rubber membrane layers can also be fitted together.

[0043] The modified nitrile rubber film is prepared by mixing inorganic hollow microspheres, additives, and a polymer of acrylonitrile and butadiene monomers to form a rubber mix, followed by a crosslinking reaction. The polymer of acrylonitrile and butadiene monomers is a polymer synthesized from acrylonitrile and butadiene as base monomers. The molecular formula of this polymer is shown below in Formula (I).

[0044]

[0045] In formula (I), x, y, and z are natural numbers.

[0046] Among them, the modified nitrile rubber membrane layer is made by adding inorganic hollow microspheres to nitrile rubber. Specifically, by mixing the inorganic hollow microspheres, additives and a polymer of acrylonitrile and butadiene monomers, a rubber mix can be formed, and the rubber mix can form a modified nitrile rubber membrane layer after vulcanization. In other words, the polymer of acrylonitrile and butadiene monomers can form nitrile rubber, and nitrile rubber is equivalent to the base material of the diaphragm material. After the inorganic hollow microspheres and the polymer of acrylonitrile and butadiene monomers go through the mixing process, the inorganic hollow microspheres can be evenly dispersed in the base material. Since the density of the inorganic hollow microspheres is less than that of the rubber, by adding the inorganic hollow microspheres to the rubber, the density of the diaphragm material can be reduced to obtain a low-density diaphragm.

[0047] Furthermore, the diameter of the inorganic hollow microspheres is 10 μm to 100 μm, preferably 15 μm to 70 μm. For example, the diameter of the inorganic hollow microspheres can be 10 μm, 15 μm, 20 μm, 30 μm, 40 μm, 50 μm, 60 μm, 70 μm, 80 μm, 90 μm or 100 μm. In other words, inorganic hollow microspheres of different diameters can be selected according to the thickness of the diaphragm to ensure that the inorganic hollow microspheres are evenly dispersed in the substrate.

[0048] In addition, as the diameter of the inorganic hollow microspheres decreases, the distribution density of the inorganic hollow microspheres will increase. The distribution density of the inorganic hollow microspheres can be controlled at 0.15 g / cm 3 ~0.9g / cm 3 For example, the distribution density of inorganic hollow microspheres can be 0.15 g / cm 3 , 0.2g / cm 3 , 0.25g / cm 3 , 0.5g / cm 3 , 0.6g / cm 3 , 0.7g / cm 3 , 0.8g / cm 3 or 0.9g / cm 3 To ensure that the inorganic hollow microspheres can effectively reduce the density of the diaphragm, the distribution density of the inorganic hollow microspheres is preferably 0.25 g / cm 3 ~0.8g / cm 3 .

[0049] Furthermore, the specific surface area of ​​the inorganic hollow microspheres is ≥0.9, and the loss factor of the modified nitrile rubber film layer at room temperature is >0.13. Figure 1 As shown, different lines represent different inorganic hollow microsphere diameters. As the diameter of the inorganic hollow microspheres decreases, the loss factor of the vulcanized rubber at room temperature increases. The specific surface area is inversely proportional to the diameter: smaller diameter inorganic hollow microspheres have a larger specific surface area, while larger diameter inorganic hollow microspheres have a smaller specific surface area. Under the same process conditions, the contact area between the macromolecular chain and the smaller diameter inorganic hollow microspheres increases. Smaller diameter inorganic hollow microspheres are tightly wrapped by the rubber, and the inorganic hollow microspheres are embedded in the rubber matrix. The more chemical and physical bonding points there are, the greater the interaction force between the inorganic hollow microspheres and the rubber. When deformed by external force, the friction between the inorganic hollow microspheres and the rubber matrix increases, the greater the hysteresis loss generated under dynamic strain, and the correspondingly greater damping.

[0050] Furthermore, the loss factor can be adjusted in conjunction with the diaphragm thickness to further optimize diaphragm performance. Generally, a higher loss factor indicates better material damping. Improving the damping of the diaphragm material helps reduce polarization during vibration, lowering product distortion and improving audio yield. For example, the loss factor can be 0.14, 0.15, 0.16, 0.17, 0.18, 0.19, 0.2, or 0.25.

[0051] The smaller the diameter of the inorganic hollow microspheres, the greater the surface area per unit mass, and the greater their reinforcing effect on rubber. However, this increase in specific surface area significantly impacts the processing properties of unvulcanized rubber, reducing its filling capacity, increasing mixing time, decreasing its dispersion ability, increasing its roll-off resistance, and increasing its viscosity. Larger diameters of inorganic hollow microspheres result in a smaller specific surface area per unit mass, and the bond strength between the inorganic hollow microspheres and rubber is weak.

[0052] The inorganic hollow microspheres selected in this application have a diameter that satisfies the processing properties of the vulcanized rubber, exhibits good dispersibility, and exhibits excellent roll-off performance. Furthermore, their large specific surface area facilitates a close bond between the inorganic hollow microspheres and the rubber, providing reinforcement. Alternatively, the inorganic hollow microspheres may be hollow microspheres made of inorganic materials, such as hollow glass microspheres or ceramic glass microspheres.

[0053] Table 1 shows the effect of inorganic hollow microspheres with the same addition amount and different diameters on the tensile strength of the rubber mix.

[0054] Table 1

[0055] Inorganic hollow microsphere diameter (μm) 5 10 30 50 70 <![CDATA[Specific surface area (m 2 / g)]]> 2.5 2.0 1.2 0.9 0.7 Tensile strength (MPa) 12 10 7 4 3

[0056] As can be seen from Table 1, the larger the diameter of the hollow glass microspheres, the smaller the specific surface area of ​​the hollow glass microspheres, and the lower the tensile strength of the modified nitrile rubber film. The inorganic hollow microspheres selected here are hollow glass microspheres. It should be noted that hollow glass microspheres are a type of inorganic hollow microspheres. Whether hollow glass microspheres or other inorganic hollow microspheres are used, the role played by the inorganic hollow microspheres in the material can be equally reflected. In other words, the smaller the diameter of the inorganic hollow microspheres, the better the reinforcement and the higher the tensile strength. The larger the diameter, the worse the reinforcement and the lower the tensile strength. Poor tensile strength can easily cause the film to break during high-power vibration.

[0057] Therefore, according to the diaphragm of the sound-emitting device according to the embodiment of the present application, the modified nitrile rubber membrane layer is prepared by cross-linking reaction after mixing inorganic hollow microspheres, additives and a polymer of acrylonitrile and butadiene monomers to form a mixed rubber, thereby improving the density of the modified nitrile rubber membrane layer, and at the same time, the tensile strength and reliability of the modified nitrile rubber membrane layer with the addition of inorganic hollow microspheres are effectively improved.

[0058] According to one embodiment of the present application, the compressive strength of the inorganic hollow microspheres is ≥10 MPa.

[0059] In other words, the high compressive strength of the inorganic hollow microspheres not only prevents them from being crushed during the mixing process, but also effectively increases the tensile strength of the modified nitrile rubber membrane when added to the polymer of acrylonitrile and butadiene monomers. The high mechanical strength of the diaphragm prevents it from overstretching due to excessive driving forces in extreme environments, further ensuring the effectiveness of the diaphragm.

[0060] In some specific embodiments of the present application, the content of the inorganic hollow microspheres accounts for 5 wt% to 45 wt% of the total rubber mix.

[0061] That is to say, inorganic hollow microspheres can be added to the polymer of acrylonitrile and butadiene monomers, accounting for 5wt% to 45wt% of the total amount of the mixed rubber, preferably 10wt% to 40wt%. As the amount of inorganic hollow microspheres added increases, the density of the modified nitrile rubber film layer decreases, and the diaphragm material with the required performance can be obtained by controlling the amount of inorganic hollow microspheres added. The content of inorganic hollow microspheres can be any value between 5wt% and 45wt%, for example, the content of inorganic hollow microspheres can be 5wt%, 10wt%, 15wt%, 20wt%, 30wt%, 40wt% or 45wt%.

[0062] It should be noted that, since the density of inorganic hollow microspheres is much lower than that of rubber, the density of the rubber material will decrease significantly as the added mass of inorganic hollow microspheres increases. Specifically, when the content of inorganic hollow microspheres is low (less than 5wt%), it has little effect on the density of the diaphragm material, and the diaphragm still has a relatively high density. When the content of inorganic hollow microspheres is too high (greater than 45wt%), due to its excessive mechanical strength, the maximum amplitude that can be achieved by the prepared diaphragm under the same driving force is reduced, which reduces the low frequency Fr of the generating device. Moreover, the addition of excessive inorganic hollow microspheres will significantly reduce the density of the modified nitrile rubber membrane layer, and the prepared diaphragm will have low elongation at break and strength, and will be prone to reliability issues such as collapse and film breakage.

[0063] like Figure 2 As shown, the different linear relationships represent different inorganic hollow microsphere content. As the inorganic hollow microsphere content increases, the loss factor of the modified nitrile rubber film layer significantly increases. Because the inorganic hollow microspheres are encapsulated by the rubber, a very thin polymer layer forms between them. The interaction between the inorganic hollow microspheres and the rubber restricts the movement of the rubber segments within this polymer layer. As the inorganic hollow microsphere dosage increases, the content of this restricted polymer layer continues to increase, increasing friction between the rubber and the inorganic hollow microspheres, and between the inorganic hollow microspheres themselves. This improves the system's ability to dissipate energy, thereby increasing the loss factor.

[0064] As the dosage of inorganic hollow microspheres continues to increase, they enter the cavities between polymer chain segments, reducing the free volume of the inorganic hollow microspheres and rubber system. This restricts the relaxation movement of some molecular segments and reduces the internal friction of molecular chain movement, thereby reducing the loss factor. When the dosage of inorganic hollow microspheres reaches a certain level, their dispersibility in the rubber matrix deteriorates, and the active points of bonding between the inorganic hollow microspheres and the rubber decrease accordingly. This results in a lower mass fraction of bound rubber, weakened interfacial interactions, and the inorganic hollow microspheres forming loosely structured aggregates in the rubber matrix, thereby affecting the dynamic mechanical properties of the rubber. Therefore, when the dosage of inorganic hollow microspheres is large, the loss factor of the vulcanized rubber actually decreases.

[0065] Table 2

[0066] Hollow glass microsphere addition amount (wt%) 0 5 10 40 50 Elongation at break (%) 572 432 375 298 161

[0067] As shown in Table 2, the elongation at break of the modified nitrile rubber membrane decreases with increasing hollow glass microsphere usage. This suggests that increasing the amount of inorganic hollow microspheres leads to uneven dispersion within the matrix, poor bonding between the microspheres and the rubber, and limited reinforcement. This poses a risk of membrane rupture during long-term use.

[0068] The inorganic hollow microspheres herein are hollow glass microspheres. It should be noted that hollow glass microspheres are a type of inorganic hollow microspheres, and the use of hollow glass microspheres or other inorganic hollow microspheres can equally demonstrate the role played by the inorganic hollow microspheres in the material. Thus, by using a modified nitrile rubber membrane layer prepared by adding 5wt% to 45wt% of inorganic hollow microspheres to the total rubber mix as the diaphragm material, both the density and strength of the diaphragm can be balanced. After vulcanization of the rubber mix with this addition, the diaphragm has appropriate damping, suppresses diaphragm polarization, and achieves good sound quality, low distortion, and superior mechanical properties, meeting both acoustic performance and reliability requirements.

[0069] According to some embodiments of the present application, the density of the modified nitrile rubber film layer is 0.5 g / cm 3 ~1.1g / cm 3 For example, the density of the modified nitrile rubber film layer can be 0.5g / cm 3 , 0.6g / cm 3 , 0.7g / cm 3 , 0.8g / cm 3 , 0.9g / cm 3 , 1g / cm 3 or 1.1 g / cm 3 Thus, through the above-mentioned setting, the weight of the modified nitrile rubber membrane layer can be reduced by 30%-50%, which greatly improves the sound sensitivity of the diaphragm.

[0070] According to one embodiment of the present application, after the modified nitrile rubber film layer is aged in hot air at 100° C. for 168 hours, the tensile strength of the modified nitrile rubber film layer decreases by ≤45%, and the elongation at break decreases by ≤70%.

[0071] Specifically, hollow glass microspheres, composed of borosilicate, have high temperature resistance. When added to NBR (nitrile butadiene rubber), they form a dense protective layer on the rubber surface, hindering the penetration of oxygen molecules and effectively improving the aging resistance of the modified nitrile butadiene rubber film. Table 3 shows the effect of varying concentrations of inorganic hollow microspheres on the decrease in tensile strength and elongation at break of modified nitrile butadiene rubber films after aging at 100°C for 168 hours.

[0072] Table 3

[0073] Hollow glass microsphere addition amount (wt%) 0 5 10 40 50 Percentage decrease in tensile strength after aging (%) 51.7 45 41.4 32.6 30.5 Percentage decrease of elongation at break (%) 75.6 69.7 67.1 42.1 32.6

[0074] As shown in Table 3, when the mass fraction of hollow glass microspheres is 0, the percentage decrease in tensile strength after aging is 51.7%, and the elongation at break is 75.6%. Hollow glass microspheres are selected as the inorganic hollow microspheres here. It should be noted that hollow glass microspheres are a type of inorganic hollow microspheres. Whether hollow glass microspheres or other inorganic hollow microspheres are used, the role played by inorganic hollow microspheres in the material can be equally reflected. In other words, as the mass fraction of inorganic hollow microspheres increases, the tensile strength and elongation at break of the modified nitrile rubber film layer gradually decrease after aging.

[0075] The diaphragm of the embodiment of the present application and the conventional NBR rubber diaphragm were placed at 100°C for 168 hours and then used in loudspeakers to test their total harmonic distortion. The test results are as follows: Figure 3 As shown, after being stored at 100°C for 168 hours, the speaker diaphragm of the embodiment of the present application exhibits lower total harmonic distortion than a conventional NBR rubber diaphragm. This demonstrates that the diaphragm of the embodiment of the present application maintains excellent resilience even after high-temperature storage. During vibration, the diaphragm exhibits less rocking vibration, resulting in better sound quality and listening stability.

[0076] In some specific embodiments of the present application, the modified nitrile rubber membrane layer has a tensile strength of 2 MPa to 45 MPa when pulled apart. That is, after forming a low-density rubber diaphragm material by adding inorganic hollow microspheres to a polymer of acrylonitrile and butadiene monomers, the tensile strength of the diaphragm material when pulled apart can be controlled to be within the range of 2 MPa to 45 MPa. For example, the tensile strength of the modified nitrile rubber can be 2 MPa, 6 MPa, 10 MPa, 16 MPa, 20 MPa, 25 MPa, 30 MPa, 40 MPa, or 45 MPa.

[0077] According to one embodiment of the present application, the tear strength of the modified nitrile rubber membrane layer is 15N / mm to 100N / mm. That is to say, when the diaphragm material is pulled apart, the tear strength can be controlled within the range of 15N / mm to 100N / mm. The tear strength of the modified nitrile rubber can be 15N / mm, 30N / mm, 45N / mm, 50N / mm, 70N / mm, 90N / mm or 100N / mm. That is, the modified nitrile rubber membrane layer can have suitable mechanical properties, and the diaphragm prepared therefrom is not prone to problems such as film breakage during use of the sound-generating device, effectively ensuring the reliability of the diaphragm.

[0078] According to some embodiments of the present application, the room temperature storage modulus of the modified nitrile rubber film layer is 0.5 MPa to 40 MPa.

[0079] That is to say, by adding inorganic hollow microbeads to the base rubber to form a low-density rubber diaphragm material, the room temperature storage modulus of the modified nitrile rubber membrane layer can be in the range of 0.5MPa to 40MPa, which can ensure that the diaphragm has good resilience.

[0080] The diaphragm prepared using the modified nitrile rubber membrane layer as raw material has excellent damping performance and resilience. The vibration system can effectively suppress polarization during the vibration and sound generation process. The consistency of the vibration system is better, effectively reducing the distortion of the sound-generating device.

[0081] The higher the material strength and hardness, the higher the F0 of the diaphragm material, the lower the loudness of the speaker and the worse the bass. Table 4 shows the F0 values ​​of diaphragms with the same thickness but different hardness.

[0082] Table 4

[0083] Hardness (A) 29 35 60 75 80 F0(Hz) 145 175 256 325 500

[0084] It can be seen from Table 4 that as the hardness increases, F0 increases sharply.

[0085] It should be noted that the sound-producing device can be a loudspeaker. The loudspeaker includes a vibration system and a magnetic circuit system that cooperates with the vibration system. The vibration system includes the diaphragm provided in this application, which can be a ring-shaped diaphragm or a flat diaphragm. Loudspeakers with the diaphragm provided in this application have advantages such as good sound quality and durability.

[0086] In some specific embodiments of the present application, the hardness can be 35A to 75A, and the room temperature storage modulus is 0.5MPa to 40MPa, which enables the F0 of the speaker to reach 175Hz to 325Hz, thereby achieving excellent low-frequency performance of the speaker.

[0087] According to one embodiment of the present application, the additives include a cross-linking agent, a reinforcing agent, and an antioxidant, wherein the cross-linking agent is at least one of a metal oxide, a metal peroxide, an organic oxide, and an organic peroxide system. The reinforcing agent is at least one of carbon black, white carbon black, graphene oxide, montmorillonite, talc, pottery clay, mica powder, feldspar powder, sodium alginate, magnetic powder, and diatomaceous earth. The antioxidant is at least one of antioxidant N-445, antioxidant 246, antioxidant 4010, antioxidant SP, antioxidant RD, antioxidant ODA, antioxidant OD, and antioxidant WH-02.

[0088] In some specific embodiments of the present application, the content of the cross-linking agent accounts for 0.5wt% to 6wt% of the rubber mix, the content of the reinforcing agent accounts for 5wt% to 60wt% of the rubber mix, and the content of the antioxidant accounts for 0.1wt% to 5.7wt% of the rubber mix. For example, the content of the cross-linking agent can be 0.5wt%, 1wt%, 1.5wt%, 2wt%, 2.5wt%, 3wt%, 3.5wt%, 4wt%, 4.5wt%, 5wt% or 6wt%. The content of the reinforcing agent can be 5wt%, 10wt%, 15wt%, 20wt%, 25wt%, 30wt%, 35wt%, 40wt%, 45wt%, 50wt%, 55wt% or 60wt%. The content of the antioxidant can be 0.1wt%, 0.5wt%, 1wt%, 1.5wt%, 2wt%, 2.5wt%, 3wt%, 3.5wt%, 4wt%, 4.5wt% or 5.7wt%.

[0089] The antioxidant content is 0.1-5.7% by weight of the rubber mix. Over time, rubber molecular chains break, generating free radicals that accelerate aging. Antioxidants are added to stop the generation of autocatalytic free radicals within rubber products. Too little antioxidant addition will not extend the service life, while too much antioxidant will not dissolve well in the elastomer, making it difficult to disperse evenly, leading to a decrease in the material's mechanical properties. Furthermore, antioxidants tend to precipitate on the surface over time.

[0090] The reinforcing agent accounts for 5-60% by weight of the rubber mix. The reinforcing agent interacts with the rubber molecular chains through entanglement, van der Waals forces, or hydrogen bonds. When the material is subjected to stress, the molecular chains easily slide on the reinforcing agent surface but are difficult to separate from the reinforcing agent. The rubber molecules and the reinforcing agent form a strong bond that allows sliding, increasing the mechanical strength. However, excessive reinforcing agent significantly increases the tensile strength of the material and sharply reduces the elongation at break, which cannot meet product requirements.

[0091] The cross-linking agent content accounts for 0.5wt% to 6wt% of the rubber compound, and the rubber compound has the best overall performance, with good processing performance, mechanical properties, oil resistance, and heat aging resistance. The glass transition temperature of its rubber membrane layer is ≤-20°C. This allows the speaker diaphragm to maintain good rubber elasticity when operating below 0°C, thereby providing higher sound quality. At the same time, the risk of speaker diaphragm damage in low-temperature environments is reduced, and reliability is higher. In addition, the low glass transition temperature ensures high modulus consistency when the material operates above the glass transition temperature. The F0 of the diaphragm prepared from this diaphragm material has better stability over the entire temperature range. Table 5 shows the effect of the amount of vulcanizer added on the glass transition temperature and elongation at break of the modified nitrile rubber membrane layer.

[0092] Table 5

[0093] Vulcanizing agent addition amount (wt%) 0.1 0.5 1 5 10 Glass transition temperature (℃) -43 -32 -25 -20 -15.8 Elongation at break (%) 423 362 327 290 169

[0094] It can be seen from Table 5 that with the increase of vulcanizing agent, the glass transition temperature gradually increases and the elongation at break gradually decreases.

[0095] Therefore, when the total mass of the cross-linking agent is low, the effective cross-linking density of the material is low, the mechanical strength of the material is poor, and it is easy to deform during the preparation of the diaphragm and long-term use. In addition, the vulcanization rate of the material is slow, which seriously limits production efficiency and leads to increased production costs. As the amount of vulcanizing agent increases, the scorch time of the rubber material is shortened, the vulcanization rate is accelerated, the cross-linking density of the material increases, the tensile stress, hardness, resilience, and fatigue crack resistance of the vulcanized rubber under constant load conditions are improved, the elongation at break is reduced, the permanent deformation and dynamic heat generation are reduced, the molecular chain movement is restricted, and the glass transition temperature is increased. However, if the cross-linking density is too high, the uneven distribution of cross-linking bonds will be aggravated, resulting in uneven stress distribution.

[0096] According to one embodiment of the present application, the diaphragm is a single-layer structure, and the diaphragm is composed of a layer of modified nitrile rubber membrane.

[0097] In some specific embodiments of the present application, the diaphragm is a composite layer structure, and the diaphragm further includes a membrane layer made of at least one of a thermoplastic elastomer, an engineering plastic, and a thermosetting elastomer.

[0098] The thermoplastic elastomer is selected from at least one of thermoplastic polyester elastomers, thermoplastic polyurethane elastomers, thermoplastic polyamide elastomers, and silicone elastomers. The engineering plastic is selected from at least one of polyetheretherketone, polyarylate, polyetherimide, polyimide, polyphenylene sulfide, polyethylene naphthalate, polyethylene terephthalate, and polybutylene terephthalate. The thermosetting elastomer is selected from at least one of natural rubber (NR), styrene-butadiene rubber (SBR), butadiene rubber (BR), isoprene rubber (IR), chloroprene rubber (CR), butyl rubber (IIR), nitrile rubber (NBR), chlorinated nitrile rubber (HNBR), ethylene-propylene rubber (EPDM), silicone rubber (Q), fluorosilicone rubber, fluororubber (FPM), polyurethane rubber (AU), acrylate rubber (ACM), ethylene-acrylate rubber (AEM), ethylene-vinyl acetate rubber (EVM), chlorosulfonated polyethylene rubber (CSM), epichlorohydrin rubber (CO), and polysulfide rubber.

[0099] In summary, the diaphragm of the sound-generating device according to the embodiment of the present application is a modified nitrile rubber membrane layer prepared by cross-linking reaction after kneading inorganic hollow microbeads, additives and a polymer of acrylonitrile and butadiene monomers to form a mixed rubber, thereby improving the damping performance of the modified nitrile rubber membrane layer. At the same time, the modulus change value of the modified nitrile rubber membrane layer with the addition of inorganic hollow microbeads is reduced in a high temperature environment, thereby reducing the number of swing vibrations of the diaphragm and making the resonant frequency of the diaphragm more stable. In addition, by controlling the amount of inorganic hollow microbeads added, the density of the diaphragm is reduced, and the diaphragm has excellent aging resistance and mucous membrane resistance, thereby improving the mid-frequency performance and usage performance of the generating device.

[0100] It should be noted that the diaphragm provided in this application can be used to form a sound-generating device of any structure, such as the following typical sound-generating device: comprising a vibration system and a magnetic circuit system that cooperates with the vibration system, wherein the vibration system comprises a diaphragm and a voice coil coupled to one side of the diaphragm. When the sound-generating device is in operation, the voice coil is energized and, 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 the diaphragm can produce sound when it vibrates.

[0101] According to the second aspect of the embodiment of the present application, the sound-producing device includes a vibration system and a magnetic circuit system coordinated 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 to drive the diaphragm to produce sound. The diaphragm is the diaphragm of the above embodiment.

[0102] like Figure 4 and Figure 5As shown, the sound-generating device includes a diaphragm 15 prepared according to an embodiment of the present application. The diaphragm 15 can be composed of a rim portion 151 and a dome portion 152. The modified nitrile rubber membrane layer can be applied to the rim portion 151 of the diaphragm. Those skilled in the art can make corresponding adjustments based on actual product requirements, such as increasing the rim portion 151 toward the voice coil 11, positioning the dome portion 152 on the lower surface of the rim portion 151, and adding a centering support to the vibration system.

[0103] According to the sound-generating device of the third embodiment of the present application, Figure 6 and Figure 7 As shown, it includes a shell 10 and a magnetic circuit system 14 and a vibration system arranged in the shell 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 to drive the first diaphragm 12 to make sound. The two ends of the second diaphragm 13 are respectively connected to the bottom of the shell 10 and the voice coil 11. The second diaphragm 13 is the diaphragm of the above embodiment.

[0104] That is, the sound-generating device 100 according to the embodiment of the present application may further include two diaphragms prepared according to the above-described embodiment of the present application, namely, a first diaphragm 12 and a second diaphragm 13. The first diaphragm 12 can be used to vibrate and produce 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 in operation, after the voice coil 11 is energized, the magnetic field force of the magnetic circuit system 14 causes the voice coil 11 to vibrate up and down, thereby driving the first diaphragm 12 to vibrate. The vibration of the first diaphragm 12 can produce sound. The second diaphragm 13 can also vibrate up and down following 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, prevent polarization of the voice coil 11, and thus improve the sound quality of the sound-generating device 100.

[0105] It should be noted that the first diaphragm 12 and the second diaphragm 13 may simultaneously adopt the diaphragms of the above embodiment of the present application, or one of the first diaphragm 12 and the second diaphragm 13 may adopt the diaphragm of the above embodiment of the present application. The present application does not impose any specific restrictions on this.

[0106] The diaphragm of the sound-generating device of the present application is described in detail below with reference to specific embodiments.

[0107] Example 1

[0108] The formula is as follows by weight: 100 parts of nitrile rubber, 30 parts of carbon black, 4 parts of zinc oxide, 1.5 parts of stearic acid, 3 parts of accelerator, 1.8 parts of sulfur, 2 parts of antioxidant 445, and 20 parts of hollow glass microspheres. After mixing according to the above formula, a cross-linking reaction is performed to obtain the diaphragm material. The average diameter of the hollow glass microspheres is 25μm to 35μm, and the density is 0.38g / cm 3 , with a specific surface area of ​​1.5m 2 / g, compressive strength 50MPa.

[0109] Comparative Example 1

[0110] The difference from Example 1 is that no hollow glass microspheres are added. The other preparation steps of the diaphragm material are exactly the same as those of Example 1.

[0111] Table 6 shows the performance test results of the diaphragm materials of Comparative Example 1 and Example 1, reflecting the effect of adding inorganic hollow microspheres on the tensile strength, elongation at break, swelling ratio and density of the diaphragm materials.

[0112] Test conditions:

[0113] (1) Tensile properties: The tensile strength and elongation at break were determined according to ASTM D412-2016. The specimens were dumbbell-shaped, the tensile rate was 500 mm / min, and each group of samples was tested 5 times to obtain the average value.

[0114] (2) Room temperature loss factor was determined by dynamic mechanical testing (DMA) according to ASTM D5026-15, using a tensile fixture in the test temperature range of -50°C to 200°C, a heating rate of 3°C / min, and three tests per sample to obtain the average value.

[0115] (3) The glass transition temperature test was carried out in accordance with ISO 6721-4 standard with a heating rate of 20 °C / min.

[0116] Each group of samples was tested 3 times and the average value was taken;

[0117] (4) The specific surface area was measured using a surface analyzer from Bester Company, and the specific surface area of ​​the sample was calculated using the BET method.

[0118] Table 6

[0119] / <![CDATA[Specific gravity g / cm 3 > loss factor Tensile strength MPa Elongation at break % Example 1 1.0 0.23 10 350 Comparative Example 1 1.3 0.12 12 435

[0120] As can be seen from Table 6, the density of Example 1 is lower than that of Comparative Example 1, and the weight is lighter, thereby improving the sound sensitivity of the diaphragm. Moreover, the specific surface area of ​​the hollow glass microspheres is 1.5m 2 / g, the structural strength of the diaphragm is enhanced, its loss factor and tensile strength are improved, the friction between the rubber and the hollow glass microspheres is increased, and the energy dissipation capacity of the system is improved.

[0121] That is to say, the distortion of the diaphragm produced by the embodiment of the present application is reduced. The inorganic hollow microbeads are used as the hollow material. When the rubber material is stretched, it is equivalent to reducing the cross-sectional area of ​​the material, which has a great impact on the strength of the material. However, the degree of reduction is within 20%, which fully meets the requirements of the diaphragm material and ensures the use effect of the diaphragm and the acoustic performance of the sound-emitting device.

[0122] Although some specific embodiments of the present application have been described in detail by way of examples, it should be understood by those skilled in the art that the above examples are for illustration only and are not intended to limit the scope of the present application. It should be understood by those skilled in the art that the above embodiments may be modified without departing from the scope and spirit of the present application. The scope of the present application is defined by the appended claims.

Claims

1. A diaphragm of a sound-generating device, characterized in that: The diaphragm includes at least one modified nitrile rubber membrane layer, which is prepared by mixing inorganic hollow microspheres, additives, and a polymer of acrylonitrile and butadiene monomers to form a mixed rubber and then subjecting it to a cross-linking reaction; The diameter of the inorganic hollow microspheres is 10 μm to 100 μm, and the distribution density of the inorganic hollow microspheres in the modified nitrile rubber film layer is 0.15 g / cm 3 ~0.9g / cm 3 The specific surface area of ​​the inorganic hollow microspheres is ≥0.9, the content of the inorganic hollow microspheres accounts for 5wt% to 45wt% of the total amount of the mixed rubber, and the loss factor of the modified nitrile rubber film layer at room temperature is >0.

13.

2. The diaphragm of the sound-generating device according to claim 1, wherein: After the modified nitrile rubber film layer is aged in hot air at 100° C. for 168 hours, the tensile strength of the modified nitrile rubber film layer decreases by ≤45%, and the elongation at break decreases by ≤70%.

3. The diaphragm of the sound-generating device according to claim 1, wherein: The tensile strength of the modified nitrile rubber film layer when broken is 2MPa to 45MPa.

4. The diaphragm of the sound-generating device according to claim 1, wherein: The compressive strength of the inorganic hollow microspheres is ≥10 MPa.

5. The diaphragm of the sound-generating device according to claim 1, wherein: The room temperature storage modulus of the modified nitrile rubber film layer is 0.5 MPa to 40 MPa.

6. The diaphragm of the sound-generating device according to claim 1, characterized in that The tear strength of the modified nitrile rubber film layer is 15N / mm to 100N / mm.

7. The diaphragm of the sound-generating device according to claim 1, characterized in that The additives include a cross-linking agent, a reinforcing agent and an antioxidant, wherein the cross-linking agent is at least one of a metal oxide, a metal peroxide, an organic oxide and an organic peroxide system; the reinforcing agent is at least one of carbon black, white carbon black, graphene oxide, montmorillonite, talc, clay, mica powder, feldspar powder, sodium alginate, magnetic powder and diatomaceous earth; and the antioxidant is at least one of antioxidant N-445, antioxidant 246, antioxidant 4010, antioxidant SP, antioxidant RD, antioxidant ODA, antioxidant OD and antioxidant WH-02.

8. The diaphragm of the sound-generating device according to claim 7, characterized in that: The content of the cross-linking agent accounts for 0.5wt% to 6wt% of the rubber mix, the content of the reinforcing agent accounts for 5wt% to 60wt% of the rubber mix, and the content of the antioxidant accounts for 0.1wt% to 5.7wt% of the rubber mix.

9. The diaphragm of the sound-generating device according to claim 1, characterized in that: The density of the modified nitrile rubber film layer is 0.5 g / cm 3 ~1.1g / cm 3 .

10. The diaphragm of the sound-generating device according to claim 1, wherein: The diaphragm is a single-layer structure, and the diaphragm is composed of a layer of modified nitrile rubber membrane.

11. The diaphragm of the sound-generating device according to claim 1, wherein: The diaphragm is a composite layer structure, and the diaphragm further comprises a membrane layer made of at least one of thermoplastic elastomer, engineering plastic and thermosetting elastomer.

12. A sound-generating device, characterized in that: It includes a vibration system and a magnetic circuit system coordinated 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 to drive the diaphragm to make sound, and the diaphragm is the diaphragm described in any one of claims 1-11.

13. A sound-generating device, characterized in that: It includes a shell and a magnetic circuit system and a vibration system arranged in the shell, 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 to drive the first diaphragm to make sound, the two ends of the second diaphragm are respectively connected to the shell and the bottom of the voice coil, and the second diaphragm is the diaphragm according to any one of claims 1 to 11.

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