Diaphragm and sound emitting device

Abstract

The application discloses a vibrating diaphragm and a sound generating device. The vibrating diaphragm comprises a mixing type carboxyl nitrile rubber film layer, which is formed by mixing 100 parts of carboxyl nitrile raw rubber, a vulcanizing agent, a filler, an antioxidant and other additives. The vulcanizing agent is an epoxy resin vulcanizing agent. The F0 change rate of the vibrating diaphragm at 10 DEG C to 40 DEG C is less than or equal to 20%. The carboxyl nitrile raw rubber contains carboxyl groups, and the epoxy resin vulcanizing agent contains epoxy groups. The carboxyl groups and the epoxy groups can generate alcohol ester groups under high temperature, that is, cross-linking bonds are generated, the cross-linking density is improved, the cross-linking mode is improved, and the modulus change of the vibrating diaphragm prepared is small at 10 DEG C to 40 DEG C, and the acoustic performance is better.

Description

Technical Field

[0001] This invention belongs to the field of electroacoustic equipment technology. Specifically, this invention relates to a diaphragm of a sound-generating device and a sound-generating device including the diaphragm. Background Technology

[0002] Currently, most wearable products, such as headphones, smartwatches, smart bracelets, and VR / AR products, utilize thermoplastic elastomers or rubber in their sound-generating devices. For thermoplastic elastomers, composite diaphragms made from thermoplastic polyurethane elastomer (TPU) and thermoplastic polyester elastomer (TPEE) are commonly used. For rubber materials, ethylene acrylate rubber (AEM) is predominantly employed. Diaphragms made from these materials exhibit good low-temperature resistance and bass response, thus making them widely used.

[0003] However, as the temperature rises, the chain segment mobility within the diaphragm material of such products increases, the modulus decreases, the compliance of the diaphragm increases, and the resonant frequency (F0) decreases, thus affecting the acoustic performance. Summary of the Invention

[0004] One object of the present invention is to provide a diaphragm that can solve the technical problem in the prior art that the acoustic performance of the diaphragm of a sound-generating device deteriorates as the temperature increases.

[0005] Another object of the present invention is to provide a sound-generating device having the above-described diaphragm.

[0006] According to a first aspect of the present invention, a diaphragm is provided, the diaphragm comprising a compounded carboxylated nitrile rubber film layer, the compounded carboxylated nitrile rubber film layer being compounded from 100 parts by weight of carboxylated nitrile raw rubber, a vulcanizing agent, a filler, an antioxidant and other additives, wherein the vulcanizing agent is an epoxy resin vulcanizing agent, and the diaphragm having an F0 change rate of ≤20% at 10℃~40℃.

[0007] Optionally, the vulcanizing agent comprises a difunctional epoxy resin and / or a trifunctional epoxy resin.

[0008] Optionally, the content of the vulcanizing agent is 1 part by mass to 23 parts by mass, the content of the difunctional epoxy resin is 1 part by mass to 20 parts by mass, and the amount of the trifunctional epoxy resin is 0 parts by mass to 3 parts by mass.

[0009] Optionally, the epoxy resin comprises at least one of phenolic glycidyl ether epoxy resin, glycidyl ester epoxy resin, glycidyl amine epoxy resin, linear aliphatic epoxy resin, and alicyclic epoxy resin.

[0010] Optionally, the content of acrylonitrile groups in the compounded carboxylated nitrile rubber film layer is 10wt% to 50wt%.

[0011] Optionally, the other additives include a vulcanization accelerator, which is at least one of tertiary ammonium compounds, substituted urea compounds, phenols, imidazoles, metal salts of acetylacetone, and boron trifluoride complex thiazoles.

[0012] Optionally, the content of the vulcanization accelerator is 0.1 parts by weight to 8 parts by weight.

[0013] Optionally, the filler comprises at least one of carbon black, silica, talc, calcium carbonate, magnesium carbonate, dolomite, barium sulfate, zinc sulfide, aluminum powder, graphite, titanium dioxide, zinc barium white, phenolic resin, petroleum resin, and styrene resin.

[0014] Optionally, the content of the filler is 5 parts by weight to 100 parts by weight.

[0015] Optionally, the antioxidant comprises at least one of 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.

[0016] Optionally, the antioxidant content is 0.5 parts by weight to 6 parts by weight.

[0017] Optionally, the other additives include at least one of stearic acid, ultraviolet absorber, pigment, and plasticizer.

[0018] Optionally, the diaphragm is formed as a single-layer structure comprising only one layer of the compounded carboxylated nitrile rubber film; or, the diaphragm is formed as a composite layer structure, comprising at least one layer of the compounded carboxylated nitrile rubber film.

[0019] According to a second aspect of the invention, a sound-generating device is provided, the diaphragm comprising any of the diaphragms described above.

[0020] One technical advantage of this invention lies in the fact that, during the preparation of the diaphragm, carboxyl-based nitrile rubber and an epoxy resin vulcanizing agent are used. The carboxyl-based nitrile rubber contains carboxyl groups, and the epoxy resin vulcanizing agent contains epoxy groups. The carboxyl groups and epoxy groups can generate alcohol ester groups at high temperatures, thus forming crosslinking bonds. The greater the number of crosslinking bonds, the higher the crosslinking density, and the better the modulus stability of the prepared diaphragm 10. Furthermore, the F0 change rate of the diaphragm 10 in this embodiment of the invention is ≤20% within the temperature range of 10℃ to 40℃. Therefore, the use of carboxyl-based nitrile rubber and an epoxy resin vulcanizing agent in the preparation of the diaphragm 10 in this embodiment of the invention increases the crosslinking density and improves the crosslinking method. Within the temperature range of 10℃ to 40℃, the modulus change of the diaphragm 10 is small, resulting in superior acoustic performance of the sound-generating device.

[0021] Other features and advantages of the invention will become clear from the following detailed description of exemplary embodiments of the invention with reference to the accompanying drawings. Attached Figure Description

[0022] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments of the invention and, together with their description, serve to explain the principles of the invention.

[0023] Figure 1 This is a schematic diagram of the structure of a diaphragm according to an embodiment of the present invention;

[0024] Figure 2 This is a partial cross-sectional view of a sound-generating device according to an embodiment of the present invention;

[0025] Figure 3 This is a partial cross-sectional view of a sound-generating device according to another embodiment of the present invention;

[0026] Figure 4 This is a comparison graph showing the rate of change of F0 and the rate of change of modulus of the diaphragms in the comparative and embodiment at temperatures ranging from 10°C to 40°C.

[0027] Figure label:

[0028] Diaphragm 10; Main body 11; Conductive part 12;

[0029] Voice coil 20; first diaphragm 21; second diaphragm 22. Detailed Implementation

[0030] Various exemplary embodiments of the present invention 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 invention.

[0031] The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the invention or its application or use.

[0032] 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.

[0033] 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.

[0034] 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.

[0035] The diaphragm and sound-generating device according to embodiments of the present invention will now be described in detail with reference to the accompanying drawings. Wherein, as... Figures 1 to 3 As shown, the sound-generating device can be a speaker unit, which can include a magnetic circuit system, a diaphragm 10, and a voice coil 20 disposed on the diaphragm 10. The end of the voice coil 20 away from the diaphragm 10 is inserted into the magnetic gap of the magnetic circuit system. When the speaker unit is working, current flows through the voice coil 20, and the voice coil 20 reciprocates under the action of the magnetic field force to drive the diaphragm 10 to vibrate and generate sound.

[0036] According to an embodiment of the present invention, the diaphragm 10 comprises a compounded carboxylated nitrile rubber film layer, which is compounded from 100 parts by weight of carboxylated nitrile raw rubber, a vulcanizing agent, a filler, an antioxidant and other additives. The vulcanizing agent is an epoxy resin vulcanizing agent, and the F0 change rate of the diaphragm 10 at 10°C to 40°C is ≤20%.

[0037] In other words, the material of the diaphragm 10 according to the embodiments of the present invention includes carboxylated nitrile rubber, that is, the diaphragm 10 includes a compounded carboxylated nitrile rubber film layer, which is mainly composed of carboxylated nitrile raw rubber, vulcanizing agent, filler, antioxidant and other additives.

[0038] The molecular formula of the carboxyl-containing butadiene-acrylonitrile raw rubber is shown in formula (Ⅰ) below:

[0039]

[0040] In formula (Ⅰ), a, b, c, and d are natural numbers. The original monomer of X can be an ethylene unsaturated monocarboxylic acid or an ethylene unsaturated dicarboxylic acid. The ethylene unsaturated monocarboxylic acid can be acrylic acid, methacrylic acid, ethylacrylic acid, crotonic acid, cinnamic acid, etc.; the ethylene unsaturated dicarboxylic acid can be fumaric acid, maleic acid, pentenic acid, allylmalonic acid, mesocarboxylic acid, tocanic acid, edaconic acid, niconic acid, etc.

[0041] Furthermore, the vulcanizing agent is an epoxy resin vulcanizing agent, which can react with carboxylated butadiene-acrylonitrile raw rubber as follows:

[0042]

[0043] In other words, the carboxyl-based nitrile rubber contains carboxyl groups, and the epoxy resin curing agent contains epoxy groups. The carboxyl groups and epoxy groups can generate alcohol ester groups at high temperatures, which forms cross-linking bonds. The more cross-linking bonds there are, the greater the cross-linking density, resulting in better modal stability of the prepared diaphragm 10, less change in the diaphragm's compliance with temperature, and a lower resonant frequency F0.

[0044] In this embodiment of the invention, the F0 change rate of the diaphragm 10 at 10℃~40℃ is ≤20%. It can be seen that the diaphragm 10 of this embodiment of the invention uses carboxylated nitrile rubber and epoxy resin vulcanizing agent, which improves the crosslinking density and improves the crosslinking method. Within 10℃~40℃, the modulus change of the diaphragm 10 is small, which makes the acoustic performance of the sound generating device better.

[0045] According to one embodiment of the present invention, the vulcanizing agent comprises a difunctional epoxy resin and / or a trifunctional epoxy resin. That is, in this embodiment, the vulcanizing agent can be a single-component epoxy resin vulcanizing agent or a composite epoxy resin vulcanizing agent. When using a single-component epoxy resin vulcanizing agent, the vulcanizing agent can be a difunctional epoxy resin or a trifunctional epoxy resin; the difunctional epoxy resin is a dual-functional epoxy resin. When using a composite epoxy resin vulcanizing agent, the vulcanizing agent can be a composite vulcanizing agent composed of a difunctional epoxy resin and a trifunctional epoxy resin. The trifunctional epoxy resin can rapidly increase the crosslinking density, which is beneficial to improving the modulus stability of the compounded carboxylated nitrile rubber film.

[0046] In some specific embodiments of the present invention, the content of the vulcanizing agent is 1 part by mass to 23 parts by mass, the content of the difunctional epoxy resin is 1 part by mass to 20 parts by mass, and the amount of the trifunctional epoxy resin is 0 parts by mass to 3 parts by mass. By using vulcanizing agent, difunctional epoxy resin and trifunctional epoxy resin within this content range, the acoustic performance of the diaphragm 10 within the range of 10°C to 40°C can be guaranteed.

[0047] It should be noted that if the content of difunctional epoxy resin is less than 1 part by mass, the crosslinking density is low, resulting in poor modulus stability of diaphragm 10; if the content of difunctional epoxy resin is higher than 20 parts by mass, the crosslinking density is too high, and the damping of diaphragm 10 decreases, resulting in insufficient acoustic performance of the sound-generating device.

[0048] Furthermore, the addition of trifunctional epoxy resin can reduce the amount of epoxy resin needed and more effectively increase the crosslinking density, while the damping decrease is not significant, ensuring the superior acoustic performance of the diaphragm 10. However, when the content of trifunctional epoxy resin exceeds 3 parts by mass, it can easily lead to excessively rapid crosslinking, a sharp increase in crosslinking density, and a severe decrease in damping, thus affecting the acoustic performance of the diaphragm 10.

[0049] As can be seen, in the embodiments of the present invention, by limiting the content of the vulcanizing agent to 1 part to 23 parts by mass, the content of the difunctional epoxy resin to 1 part to 20 parts by mass, and the amount of the trifunctional epoxy resin to 0 parts to 3 parts by mass, it is beneficial for the diaphragm 10 to have good acoustic performance within the range of 10°C to 40°C, and also improves the preparation efficiency of the diaphragm 10. Optionally, the content of the vulcanizing agent is 1 part by mass, the content of the difunctional epoxy resin is 1 part by mass, and the amount of the trifunctional epoxy resin is 0 parts by mass; the content of the vulcanizing agent is 23 parts by mass, the content of the difunctional epoxy resin is 20 parts by mass, and the amount of the trifunctional epoxy resin is 3 parts by mass; the content of the vulcanizing agent is 20 parts by mass, the content of the difunctional epoxy resin is 20 parts by mass, and the amount of the trifunctional epoxy resin is 0 parts by mass; the content of the vulcanizing agent is 18 parts by mass, the content of the difunctional epoxy resin is 16 parts by mass, and the amount of the trifunctional epoxy resin is 2 parts by mass, etc.

[0050] According to one embodiment of the present invention, the epoxy resin comprises at least one of phenolic glycidyl ether epoxy resin, glycidyl ester epoxy resin, glycidyl amine epoxy resin, linear aliphatic epoxy resin, and alicyclic epoxy resin. By using the above-mentioned epoxy resin, not only can the formation of crosslinking bonds between carboxyl groups and epoxy groups be satisfied, thus increasing the crosslinking density, but also the crosslinking speed can be avoided from being too slow. The prepared diaphragm 10 exhibits small modulus change within the temperature range of 10℃ to 40℃, resulting in excellent acoustic performance.

[0051] In some specific embodiments of the present invention, the acrylonitrile group content in the compounded carboxylated nitrile rubber film layer is 10wt% to 50wt%, which makes the diaphragm 10 have the advantages of oil resistance, cold resistance and high tensile strength.

[0052] It should be noted that nitrile groups are strongly polar groups with high electronegativity. When the acrylonitrile content is less than 10 wt%, the molecular chains of the compounded carboxylated nitrile rubber film have good flexibility, low intermolecular forces, and low glass transition temperature, resulting in low tensile strength and poor resilience of the diaphragm 10, which cannot meet the usage requirements of the diaphragm 10. As the acrylonitrile content increases, the polarity of the compounded carboxylated nitrile rubber film increases, the flexibility of the molecular chain decreases, the interaction force between molecular chains increases, the glass transition temperature is higher, the content of double bonds in the molecular chain decreases, and the degree of saturation increases. This leads to an increase in the oil resistance, air tightness, and relative density of the diaphragm 10, and the vulcanization speed is accelerated. The tensile strength of the diaphragm 10 is improved, but the processability, cold resistance, and resilience of the diaphragm 10 all decrease. In particular, when the content of acrylonitrile blocks is greater than 50 wt%, the cold resistance of the compounded carboxylated nitrile rubber film is poor. The prepared diaphragm 10 is prone to hardening and brittleness in extreme low-temperature environments, increasing the risk of film breakage.

[0053] As can be seen, in this embodiment of the invention, the acrylonitrile group content in the compounded carboxylated nitrile rubber film layer is 10wt% to 50wt%, which results in high tensile strength and good resilience of the diaphragm 10. Furthermore, it can maintain elasticity in extreme low-temperature environments and possesses advantages such as oil resistance, cold resistance, and high tensile strength. Optionally, the acrylonitrile group content in the compounded carboxylated nitrile rubber film layer is 10wt%, 12wt%, 15wt%, 20wt%, 30wt%, 40wt%, 50wt%, etc.

[0054] According to one embodiment of the present invention, other additives include a vulcanization accelerator, which is at least one selected from tertiary ammonium compounds, substituted ureas, phenols, imidazoles, metal salts of acetylacetone, and thiazoles containing boron trifluoride complexes. By using the above-mentioned types of vulcanization accelerators, the vulcanization rate can be increased.

[0055] In some specific embodiments of the present invention, the content of the vulcanization accelerator is 0.1 parts by weight to 8 parts by weight, which ensures that the addition of the vulcanization accelerator promotes the vulcanization process. It should be noted that if the content of the vulcanization accelerator is less than 0.1 parts by weight, it will be difficult to effectively promote the vulcanization process. Optionally, the content of the vulcanization accelerator is 0.1 parts by weight, 2 parts by weight, 4 parts by weight, 5 parts by weight, 6 parts by weight, 7 parts by weight, 8 parts by weight, etc.

[0056] According to one embodiment of the present invention, the filler comprises at least one selected from carbon black, silica, talc, calcium carbonate, magnesium carbonate, dolomite, barium sulfate, zinc sulfide, aluminum powder, graphite, titanium dioxide, zinc barium white, phenolic resin, petroleum resin, and styrene resin. By using the above-mentioned fillers, the tensile strength and elongation at break of the diaphragm 10 can be improved.

[0057] The following explanation uses carbon black as an example to illustrate the filler.

[0058] Carbon black is an amorphous structure, with particles forming aggregates through physicochemical bonding. The primary structure of carbon black consists of these aggregates, which, through van der Waals forces or hydrogen bonds, can aggregate into a spatial network structure—the secondary structure of carbon black. The surface of carbon black contains hydrogen, carboxyl, lactone, free radical, and quinone groups capable of substitution, reduction, and oxidation reactions. When carbon black is added to carboxylated acrylonitrile rubber, due to the strong interaction between the carbon black surface and the carboxylated acrylonitrile rubber interface, the molecular chains easily slide on the carbon black surface under stress, but are not easily detached from the carbon black. The elastomer and carbon black form a strong, sliding bond, increasing the mechanical strength of the diaphragm 10.

[0059] In some specific embodiments of the present invention, the filler content is 5 parts by mass to 100 parts by mass, which ensures the tensile strength and elongation at break of the diaphragm 10. It should be noted that if the carbon black content is less than 5 parts by mass, and the tensile strength of the carboxylated nitrile rubber itself is low, the tensile strength of the prepared diaphragm 10 will also be low; if the carbon black content is greater than 100 parts, the elongation at break of the diaphragm 10 will decrease. Therefore, in this embodiment, the filler content is 5 parts by mass to 100 parts by mass. Using filler within this range ensures a strong interaction between the carbon black and the carboxylated nitrile rubber interface, thereby ensuring that the prepared diaphragm 10 has high tensile strength and high elongation at break. Optionally, the filler content can be 5 parts by mass, 10 parts by mass, 20 parts by mass, 30 parts by mass, 35 parts by mass, 40 parts by mass, 60 parts by mass, 100 parts by mass, etc.

[0060] According to one embodiment of the present invention, the antioxidant comprises at least one of 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. By using the above-mentioned antioxidants, the service life of the diaphragm 10 can be extended.

[0061] In some specific embodiments of the present invention, the antioxidant content is 0.5 to 6 parts by weight, which can extend the service life of the diaphragm 10. It should be noted that if the antioxidant content is less than 0.5 parts by weight, i.e., the amount of antioxidant added is too small, it is difficult to achieve the effect of extending the service life; if the antioxidant content is greater than 6 parts by weight, i.e., the amount of antioxidant added is too large, because the antioxidant is difficult to miscibly dissolve with the elastomer and is difficult to disperse uniformly, the mechanical properties of the diaphragm 10 decrease, and it is prone to precipitate onto the surface of the diaphragm 10 over time. Therefore, using an antioxidant within this range can effectively extend the service life.

[0062] According to one embodiment of the present invention, other additives include at least one of stearic acid, ultraviolet absorber, color paste, and plasticizer. By adding different additives, the film layer can have different functions. For example, stearic acid, as a release agent, can improve lubrication during rubber compounding and product demolding during production. Color paste can dye rubber; conventional carboxylated nitrile rubber is a colored rubber with low aesthetic appeal. By adding color paste, diaphragms 10 of different colors can be made, increasing aesthetics. Plasticizer can improve the low-temperature resistance and processability of diaphragm 10. Furthermore, since the unsaturated carbon-carbon double bonds in carboxylated nitrile rubber are not completely hydrogenated, they will degrade under ultraviolet radiation. By adding ultraviolet absorber, diaphragm 10 can have ultraviolet absorption function.

[0063] According to one embodiment of the present invention, the thickness of the compounded carboxylated nitrile rubber film layer is 25 μm to 300 μm. By using a compounded carboxylated nitrile rubber film layer with a thickness within this range, it is beneficial to the preparation and use of the diaphragm 10.

[0064] In some specific embodiments of the present invention, the diaphragm 10 is formed as a single-layer structure comprising only one layer of compounded carboxylated nitrile rubber film; or, the diaphragm 10 is formed as a composite layer structure, the diaphragm 10 comprising at least one layer of compounded carboxylated nitrile rubber film.

[0065] In other words, the diaphragm 10 according to the embodiments of the present invention can be a single-layer membrane structure or a membrane structure composed of multiple membrane layers, as long as it meets the requirement that the diaphragm 10 contains at least one layer of compounded carboxylated nitrile rubber membrane. Therefore, the diaphragm 10 according to the embodiments of the present invention can meet the product requirements of different sound-generating devices.

[0066] Furthermore, the diaphragm 10 provided by this invention can be configured into a sound-generating device of any structure. For example... Figure 2As shown, the sound-generating device according to an embodiment of the present invention includes a housing, a magnetic circuit system disposed within the housing, and a vibration system cooperating with a vibration system. The vibration system includes a diaphragm 10 and a voice coil 20 coupled to one side of the diaphragm 10. The magnetic circuit system drives the voice coil 20 to vibrate, thereby causing the diaphragm 10 to produce sound. The diaphragm 10 is the diaphragm 10 described in the above embodiment. Specifically, when the sound-generating device is working, after the voice coil 20 is energized, under the action of the magnetic field force of the magnetic circuit system, the voice coil 20 can vibrate up and down to drive the diaphragm 10 to vibrate, and the diaphragm 10 can produce sound when it vibrates. The sound-generating device includes a diaphragm 10 prepared according to the above embodiment of the present invention.

[0067] In other specific embodiments of the present invention, such as Figure 3 As shown, the sound-generating device according to an embodiment of the present invention includes a housing and a magnetic circuit system and a vibration system disposed within the housing. The vibration system includes a voice coil 20, a first diaphragm 21 and a second diaphragm 22. The top of the voice coil 20 is connected to the first diaphragm 21. The magnetic circuit system drives the voice coil 20 to vibrate so as to drive the first diaphragm 21 to produce sound. The two ends of the second diaphragm 22 are respectively connected to an external circuit and the bottom of the voice coil 20. The second diaphragm 22 is the diaphragm of the above embodiment.

[0068] In other words, the sound-generating device according to the embodiments of the present invention may further include two diaphragms prepared by the above embodiments of the present invention, namely a first diaphragm 21 and a second diaphragm 22. The first diaphragm 21 can be used to vibrate and generate sound, and the second diaphragm 22 can be used to balance the vibration of the voice coil 20. Specifically, when the sound-generating device is working, after the voice coil 20 is energized, under the action of the magnetic field force of the magnetic circuit system, the voice coil 20 can vibrate up and down to drive the first diaphragm 21 to vibrate, and the first diaphragm 21 can generate sound when it vibrates. The second diaphragm 22 can also vibrate up and down with the voice coil 20. Since the two ends of the second diaphragm 22 are respectively connected to the external circuit and the bottom of the voice coil 20, the second diaphragm 22 can balance the vibration of the voice coil 20 and prevent the voice coil 20 from becoming polarized, thereby improving the sound generation effect of the sound-generating device.

[0069] It should be noted that the first diaphragm 21 and the second diaphragm 22 can both adopt the diaphragm 10 of the above embodiments of the present invention, or one of the first diaphragm 21 and the second diaphragm 22 can adopt the diaphragm 10 of the above embodiments of the present invention. The present invention does not make specific limitations in this regard.

[0070] The electronic device according to the present invention includes the sound-generating device of the above embodiment, and the sound-generating device adopts the diaphragm of the above embodiment. Since the diaphragm of the above embodiment of the present invention has the above-mentioned technical effects, the electronic device according to the present invention also has the corresponding technical effects, that is, the diaphragm 10 has a small modulus change and better acoustic performance within the range of 10℃ to 40℃.

[0071] The diaphragm 10 and the sound-generating device of the present invention will be described in detail below with reference to specific embodiments.

[0072] Example 1

[0073] Carboxylated butadiene nitrile (XNBR) raw rubber, bifunctional bisphenol A epoxy resin, trifunctional epoxy resin, modified imidazole, carbon black, and antioxidant 264 are mixed together.

[0074] The product contains 100 parts by weight of XNBR raw rubber; a composite vulcanizing agent is composed of difunctional bisphenol A epoxy resin and trifunctional epoxy resin, wherein the content of difunctional bisphenol A epoxy resin is 8 parts by weight and the content of trifunctional epoxy resin is 1.5 parts by weight; modified imidazole is used as a vulcanization accelerator, with a content of 1 part by weight; carbon black is used as a filler, with a content of 35 parts by weight; and antioxidant 264 is used as an antioxidant, with a content of 3 parts by weight.

[0075] Comparative Example 1

[0076] Carboxylated butadiene nitrile (XNBR) raw rubber, bifunctional bisphenol A epoxy resin, trifunctional epoxy resin, modified imidazole, carbon black, and antioxidant 264 are mixed together.

[0077] The product comprises 100 parts by weight of XNBR raw rubber; a composite vulcanizing agent consisting of bifunctional bisphenol A epoxy resin and trifunctional epoxy resin, wherein the content of bifunctional bisphenol A epoxy resin is 0.5 parts by weight; the content of trifunctional epoxy resin is 0.5 parts by weight; modified imidazole is used as a vulcanization accelerator, with a content of 1 part by weight; carbon black is used as a filler, with a content of 60 parts by weight; and antioxidant 264 is used as an antioxidant, with a content of 3 parts by weight.

[0078] The difference between Comparative Example 1 and Example 1 lies in the different contents of the bifunctional bisphenol A epoxy resin, the trifunctional epoxy resin, and the carbon black.

[0079] Comparative Example 2

[0080] Carboxylated butadiene nitrile (XNBR) raw rubber, bifunctional bisphenol A epoxy resin, trifunctional epoxy resin, modified imidazole, carbon black, and antioxidant 264 are mixed together.

[0081] The product contains 100 parts by weight of XNBR raw rubber; a composite vulcanizing agent is composed of difunctional bisphenol A epoxy resin and trifunctional epoxy resin, wherein the content of difunctional bisphenol A epoxy resin is 8 parts by weight and the content of trifunctional epoxy resin is 6 parts by weight; modified imidazole is used as a vulcanization accelerator, with a content of 1 part by weight; carbon black is used as a filler, with a content of 10 parts by weight; and antioxidant 264 is used as an antioxidant, with a content of 3 parts by weight.

[0082] The difference between Comparative Example 1 and Example 1 lies in the different contents of trifunctional epoxy resin and carbon black.

[0083] Comparative Example 3

[0084] AEM raw rubber, silica, dicumyl peroxide (DCP), triallyl isocyanate (TAIC), and antioxidant 264 are mixed together.

[0085] The composition includes 100 parts by weight of AEM raw rubber; 50 parts by weight of silica as filler; 2 parts by weight of dicumyl peroxide (DCP) as vulcanizing agent; 1 part by weight of triallyl isocyanate (TAIC) as vulcanization accelerator; and 3 parts by weight of antioxidant 264.

[0086] Comparative Example 4

[0087] It uses a TPU film with a thickness of 40μm and a hardness of 85A.

[0088] In the preparation of the diaphragm, Examples 1, 1, 2 and 3 were vulcanized at 200°C for 10 minutes and 3 MPa to produce diaphragms and vibrating membranes of 0.1 mm.

[0089] The embodiments 1 and comparative examples 1 to 4 of the present invention are all based on the diaphragm with similar F0.

[0090] The modulus, modulus change rate, damping, and F0 and F0 change rate at different temperatures of the diaphragms prepared in Example 1 and Comparative Examples 1 to 4 were measured, and their sound quality was assessed. The measurement results are shown in Tables 1 and 2 below, and plotted based on Tables 1 and 2. Figure 4 This improves intuitiveness.

[0091] Wherein, the rate of change of modulus = (E 10 -E 40 ) / E 10 *100, E 10 With E 40 These represent the modulus at 10℃ and 40℃, respectively.

[0092] F0 rate of change = (F 10 -F 40 ) / F 10 *100, F 10 With F 40 These represent F0 at 10℃ and 40℃, respectively.

[0093] Table 1. Modulus, rate of change of modulus and damping at different temperatures

[0094]

[0095] Table 2. Listening quality of F0 and F0 change rate at different temperatures

[0096]

[0097] First, combining Table 1, Table 2 and Figure 4 Example 1 and Comparative Example 1 are compared.

[0098] The difference between Comparative Example 1 and Example 1 lies in the different contents of the bifunctional bisphenol A epoxy resin, the trifunctional epoxy resin, and the carbon black.

[0099] As shown in Table 1, the diaphragm of Example 1 has a modulus of 16.1 MPa at 10°C and 14.8 MPa at 40°C, with a modulus change rate of 8.1% from 10°C to 40°C; and a damping of 0.21 at 20°C. In contrast, the diaphragm of Comparative Example 1 has a modulus of 17.2 MPa at 10°C and 11.6 MPa at 40°C, with a modulus change rate of 32.6% from 10°C to 40°C; and a damping of 0.23 at 20°C. It is evident that the diaphragm prepared in Example 1 exhibits a small modulus change rate and high modulus stability from 10°C to 40°C, and also possesses high damping; while the modulus stability of Comparative Example 1 is poor.

[0100] As shown in Table 2, the diaphragm of Example 1 has an F0 of 224 Hz at 10℃ and an F0 of 207 Hz at 40℃, with an F0 change rate of 7.6% between 10℃ and 40℃, and a listening quality of 100% at 20℃. In contrast, the diaphragm of Comparative Example 1 has an F0 of 221 Hz at 10℃ and an F0 of 158 Hz at 40℃, with an F0 change rate of 28.6% between 10℃ and 40℃, and a listening quality of 95% at 20℃. Therefore, the diaphragm prepared in Example 1 has a smaller modulus change rate and a higher listening quality between 10℃ and 40℃ compared to the diaphragm in Comparative Example 1.

[0101] This is because Comparative Example 1 used 0.5 parts of difunctional bisphenol A epoxy resin and 0.5 parts of trifunctional epoxy resin; while Example 1 used 8 parts of difunctional bisphenol A epoxy resin and 1.5 parts of trifunctional epoxy resin. It is evident that the smaller amount of vulcanizing agent in Comparative Example 1 resulted in a lower crosslinking density, leading to a larger rate of change in modulus and F0 of the diaphragm at different temperatures. Similarly, Example 1 exhibited higher damping and better sound quality.

[0102] Furthermore, comparing Example 1 and Comparative Example 2 using Tables 1 and 2, the modulus change rate of the diaphragm in Comparative Example 2 was 8.1% and the F0 change rate was 3.5% between 10°C and 40°C. However, its damping was 0.03 at 20°C, and its sound quality was 95%. It is evident that Comparative Example 2 had excessively high crosslinking density, resulting in good modulus and F0 stability, but very low damping and susceptibility to polarization, thus leading to a low sound quality.

[0103] Furthermore, by comparing Example 1, Comparative Example 3, and Comparative Example 4 with Tables 1 and 2, the F0 change rate of Comparative Example 3 from 10℃ to 40℃ was 14.3%, and the F0 change rate of Comparative Example 4 from 10℃ to 40℃ was 30.2%. It can be seen that although Comparative Example 3 and Comparative Example 4 both have good listening yield, their F0 stability is poor because their modulus changes greatly with temperature.

[0104] Therefore, it can be seen that, according to the embodiments of the present invention, the diaphragm 10, by using an epoxy resin curing agent, has an F0 change rate of ≤20% at 10℃~40℃, which can improve the crosslinking density and improve the crosslinking mode. Within 10℃~40℃, the modulus change of the diaphragm 10 is small, and the acoustic performance is better.

[0105] In summary, the diaphragm according to the embodiments of the present invention comprises a compounded carboxylated nitrile rubber membrane layer. During the preparation of the compounded carboxylated nitrile rubber membrane layer, carboxylated nitrile rubber is used, and an epoxy resin vulcanizing agent is employed. The raw carboxylated nitrile rubber contains carboxyl groups, and the epoxy resin vulcanizing agent contains epoxy groups. The carboxyl groups and epoxy groups can generate alcohol ester groups at high temperatures, thus forming crosslinking bonds. The greater the number of crosslinking bonds, the higher the crosslinking density, and the better the modulus stability of the prepared diaphragm 10. Furthermore, the F0 change rate of the diaphragm 10 in the embodiments of the present invention is ≤20% at 10℃~40℃. It is evident that the use of carboxylated nitrile rubber and an epoxy resin vulcanizing agent in the preparation process of the diaphragm 10 in the embodiments of the present invention increases the crosslinking density and improves the crosslinking method. Within the temperature range of 10℃~40℃, the modulus change of the diaphragm 10 is small, resulting in superior acoustic performance of the sound-generating device.

[0106] While specific embodiments of the invention have been described in detail by way of examples, those skilled in the art should understand that the examples are for illustrative purposes only and not intended to limit the scope of the invention. Those skilled in the art should understand that modifications can be made to the above embodiments without departing from the scope and spirit of the invention. The scope of the invention is defined by the appended claims.

Claims

1. A diaphragm, characterized in that, The diaphragm comprises a compounded carboxylated nitrile rubber film layer, which is composed of 100 parts by weight of carboxylated nitrile raw rubber, a vulcanizing agent, filler, antioxidant, and other additives. The vulcanizing agent is an epoxy resin vulcanizing agent, comprising difunctional epoxy resin and trifunctional epoxy resin. The content of the vulcanizing agent is 1 to 23 parts by weight, the content of the difunctional epoxy resin is 1 to 20 parts by weight, and the amount of the trifunctional epoxy resin is 0 to 3 parts by weight. The content of acrylonitrile groups in the compounded carboxylated nitrile rubber film layer is 10 wt% to 50 wt%, and the F0 change rate of the diaphragm at 10℃ to 40℃ is ≤20%.

2. The diaphragm according to claim 1, characterized in that, The epoxy resin comprises at least one of the following: phenolic glycidyl ether epoxy resin, glycidyl ester epoxy resin, glycidyl amine epoxy resin, linear aliphatic epoxy resin, and alicyclic epoxy resin.

3. The diaphragm according to claim 1, characterized in that, The other additives include vulcanization accelerators, which are at least one of tertiary ammonium compounds, substituted urea compounds, phenols, imidazoles, metal salts of acetylacetone, and boron trifluoride complex thiazoles.

4. The diaphragm according to claim 3, characterized in that, The content of the vulcanization accelerator is 0.1 parts by weight to 8 parts by weight.

5. The diaphragm according to claim 1, characterized in that, The filler comprises at least one of carbon black, silica, talc, calcium carbonate, magnesium carbonate, dolomite, barium sulfate, zinc sulfide, aluminum powder, graphite, titanium dioxide, zinc barium white, phenolic resin, petroleum resin, and styrene resin.

6. The diaphragm according to claim 5, characterized in that, The content of the filler is 5 parts by weight to 100 parts by weight.

7. The diaphragm according to claim 1, characterized in that, The antioxidants include 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.

8. The diaphragm according to claim 7, characterized in that, The antioxidant content is 0.5 parts by weight to 6 parts by weight.

9. The diaphragm according to claim 1, characterized in that, The other additives include at least one of stearic acid, ultraviolet absorbers, pigments, and plasticizers.

10. The diaphragm according to any one of claims 1-9, characterized in that, The diaphragm is formed as a single-layer structure comprising only one layer of the compounded carboxylated butadiene-acrylonitrile rubber film layer; Alternatively, the diaphragm may be formed as a composite layer structure, the diaphragm comprising at least one layer of the compounded carboxylated nitrile rubber film.

11. A sound-generating device, characterized in that, Includes the diaphragm as described in any one of claims 1 to 10.

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