Diaphragm for sound production device, sound production device, and electronic device

Abstract

The application discloses a vibrating diaphragm for a sound production device, a sound production device and an electronic device. The vibrating diaphragm comprises a butadiene styrene rubber layer, the butadiene styrene rubber layer is prepared from a blended material, the blended material comprises a first butadiene styrene copolymer and a second butadiene styrene copolymer, the mass percentage of styrene in the first butadiene styrene copolymer is 8% to 12%, the mass percentage of styrene in the second butadiene styrene copolymer is 40% to 50%, and the mass percentage of the first butadiene styrene copolymer in the blended material is 50% to 80%; and the glass transition temperature of the butadiene styrene rubber layer is -40 DEG C to 0 DEG C. The blended material of the application comprises the first butadiene styrene copolymer with a low glass transition temperature and the second butadiene styrene copolymer with a high glass transition temperature, and in this way, the damping temperature range of the butadiene styrene rubber layer can be effectively widened, so that the vibrating diaphragm has a high loss factor in the temperature range of -60 DEG C to 20 DEG C.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of electro-acoustic conversion, and more particularly to a diaphragm for a sound emitting device, a sound emitting device and an electronic device. BACKGROUND

[0002] In the related art, the material of the loudspeaker diaphragm is paper-based, polypropylene, NBR or metal alloy, etc. The above diaphragm has the following problems: strong temperature sensitivity, the material modulus decreases obviously at high temperature (e.g. ≥60℃), resulting in large F0 offset; the material rigidity increases at low temperature (e.g. -60℃ to 10℃), the damping loss factor is lower than 0.1, the damping is small, resulting in high THD distortion of the loudspeaker and poor listening performance in the use temperature range. In addition, the elastic recovery rate of the above diaphragm is low, resulting in residual deformation of the material after vibration, affecting the accuracy and clarity of the sound, and the low resilience material will irreversibly deform under long-term large amplitude operation, the size of the diaphragm will increase, and the overall position will deviate from the initial equilibrium position, affecting the sound emitting effect. SUMMARY

[0003] An object of the present application is to provide a new technical solution for a diaphragm for a sound emitting device.

[0004] According to a first aspect of the present application, a diaphragm for a sound emitting device is provided. The diaphragm comprises a styrene-butadiene rubber layer prepared from a blended material, the blended material comprising a first styrene-butadiene copolymer and a second styrene-butadiene copolymer, the mass percentage content of styrene in the first styrene-butadiene copolymer being 8%-12%, the mass percentage content of styrene in the second styrene-butadiene copolymer being 40%-50%, the mass percentage content of the first styrene-butadiene copolymer in the blended material being 50%-80%, and the mass percentage content of the second styrene-butadiene copolymer in the blended material being 20%-50%; the glass transition temperature of the styrene-butadiene rubber layer being -40℃ to 0℃; the ratio of F0 of the diaphragm at 23℃ to F0 at -20℃ being greater than or equal to 0.2 and less than 1, the loss factor of the diaphragm in the temperature range of -60℃ to 20℃ being ≥0.15, and the elastic recovery rate of the diaphragm at 10% tensile strain being ≥85%.

[0005] Optionally, the molecular structure of the first styrene-butadiene copolymer and / or the second styrene-butadiene copolymer is:

[0006] ,

[0007] wherein x, y, z are natural numbers.

[0008] Optionally, the glass transition temperature of the first styrene-butadiene copolymer is -60℃ to -50℃, and the glass transition temperature of the second styrene-butadiene copolymer is -20℃ to 5℃.

[0009] Optionally, the blended material further comprises a filler, the filler comprising at least one of silica, carbon black, mineral whisker, talc, diatomite, calcium carbonate, graphite, kaolin, mica; the mass percentage content of the filler in the blended material being 30%-60%.

[0010] Optionally, the blended material further comprises a vulcanizing agent, the vulcanizing agent comprising at least one of a sulfur system and a peroxide system, the mass percentage content of the vulcanizing agent in the blended material being 0.5%-3%.

[0011] Optionally, the vulcanizing agent comprises a sulfur system, the sulfur system comprising at least one of sulfur, amine sulfenamide accelerator, thiuram accelerator, zinc oxide, stearic acid;

[0012] and / or, the vulcanizing agent comprises a peroxide system, the peroxide system comprising at least one of dicumyl peroxide, dibenzoyl peroxide, tert-butyl peroxybenzoate, dilauroyl peroxide, 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane, cumene hydroperoxide.

[0013] Optionally, the blended material further comprises an accelerator, the accelerator comprising at least one of tetramethylthiuram disulfide, tetraethylthiuram disulfide, 2-mercaptobenzothiazole, dibenzothiazyl disulfide, N-cyclohexyl-2-benzothiazole sulfenamide, N-tert-butyl-2-benzothiazole sulfenamide, zinc dimethyl dithiocarbamate, diphenyl guanidine, amine sulfenamide accelerator, thiuram accelerator, zinc oxide, stearic acid; the mass percentage content of the accelerator in the blended material being 0.2%-2%.

[0014] Optionally, the blended material further comprises an antioxidant, the antioxidant comprising at least one of N-isopropyl-N'-phenyl-p-phenylenediamine, N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine, N,N'-diphenyl-p-phenylenediamine, N-phenyl-β-naphthylamine, 2,6-di-tert-butyl-p-cresol, 2,2'-methylenebis(4-methyl-6-tert-butylphenol), 2,2,4-trimethyl-1,2-dihydroquinoline, 2-mercaptobenzimidazole, 6-ethoxy-2,2,4-trimethyl-1,2-dihydroquinoline; the mass percentage content of the antioxidant in the blended material being 0.5%-4%.

[0015] Optionally, the diaphragm is formed as a single-layer structure, the diaphragm consisting of one layer of the butadiene-styrene rubber layer;

[0016] Or, the diaphragm is formed as a multi-layer structure, the diaphragm comprises at least one layer of the butadiene styrene rubber layer and a composite layer, the composite layer is arranged in a stack with the butadiene styrene rubber layer, and the composite layer is at least one of an elastomer layer, an engineering plastic layer and a film layer.

[0017] According to a second aspect of the present application, a sound generating device is provided. The sound generating device comprises the diaphragm according to the present application.

[0018] According to a third aspect of the present application, an electronic device is provided. The electronic device comprises the sound generating device according to the present application.

[0019] In the embodiment of the present application, the diaphragm comprises a butadiene styrene rubber layer prepared from a blended material. The blended material comprises a first butadiene styrene copolymer with a low glass transition temperature and a second butadiene styrene copolymer with a high glass transition temperature, and the glass transition temperature of the butadiene styrene rubber layer obtained after cross-linking reaction is -40℃ to 0℃. In this way, the damping temperature range of the butadiene styrene rubber layer can be effectively widened, so that the diaphragm has a higher loss factor and good damping performance in the temperature range of -60℃ to 20℃. When the mass percentage content of the first butadiene styrene copolymer in the blended material is 50%-80%, the diaphragm has high damping performance while the elastic recovery rate is still maintained at a high level, the loss factor of the diaphragm in the temperature range of -60℃ to 20℃ is ≥0.15, and the elastic recovery rate of the diaphragm under a tensile strain of 10% is ≥85%. The sound generating device using the diaphragm has a small THD distortion and a higher listening rate. The ratio of F0 of the diaphragm 20 at 23℃ to F0 at -20℃ is greater than or equal to 0.2 and less than 1, indicating that the diaphragm 20 has good vibration stability at different temperatures.

[0020] Other features of the present application, and their advantages, will become apparent in the non-limiting detailed description of exemplary embodiments of the present application, taken in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF DRAWINGS

[0021] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the application and, together with the description, serve to explain the principles of the application.

[0022] Figure 1 is a sectional view of a diaphragm according to an embodiment of the present application.

[0023] Figure 2 is a perspective view of a sound generating device according to an embodiment of the present application.

[0024] Figure 3 is a sectional view of a sound generating device according to an embodiment of the present application.

[0025] Figure 4is a cross-sectional view of a sound generating device according to another embodiment of the present application.

[0026] Figure 5 is a total harmonic distortion (THD) curve of sound generating devices of embodiments and comparative examples of the present application.

[0027] Reference numerals:

[0028] 100, sound generating device; 10, housing; 20, diaphragm; 30, voice coil; 40, permanent magnet. DETAILED DESCRIPTION

[0029] Various exemplary embodiments of the present application will now be described in detail with reference to the accompanying drawings. It should be noted that the relative arrangement of components and steps, numerical expressions, and numerical values set forth in these embodiments are not limiting to the scope of the present application unless otherwise specifically stated.

[0030] The following description of at least one exemplary embodiment is merely illustrative in nature and is in no way limiting to the scope of the application and its applications or uses.

[0031] Techniques, methods, and apparatus known to those of ordinary skill in the relevant art can not be discussed in detail herein, but should be considered as part of the specification, where appropriate.

[0032] In all of the compositions and methods described herein, any of the specific values stated can be replaced by alternative values of the same dimension, unless otherwise specifically stated.

[0033] It should be noted that like numerals and letters refer to like items throughout the several views, as such, once an item is defined in one view, it need not be discussed further in subsequent views.

[0034] A diaphragm 20 for a sound generating device according to embodiments of the present application will now be described in detail with reference to the accompanying drawings.

[0035] According to one embodiment of the present application, a vibrating diaphragm for a sound emitting device is provided. The vibrating diaphragm comprises a butadiene styrene rubber layer, the butadiene styrene rubber layer is prepared from a blended material, the blended material comprises a first butadiene styrene copolymer and a second butadiene styrene copolymer, the first butadiene styrene copolymer has a mass percentage of styrene of 8%-12%, the second butadiene styrene copolymer has a mass percentage of styrene of 40%-50%, the first butadiene styrene copolymer has a mass percentage of 50%-80% in the blended material, and the second butadiene styrene copolymer has a mass percentage of 20%-50% in the blended material; the butadiene styrene rubber layer has a glass transition temperature of -40℃ to 0℃; the ratio of F0 of the vibrating diaphragm at 23℃ to F0 at -20℃ is greater than or equal to 0.2 and less than 1, the loss factor of the vibrating diaphragm in the temperature range of -60℃ to 20℃ is ≥0.15, and the elastic recovery rate of the vibrating diaphragm under 10% tensile strain is ≥85%.

[0036] Specifically, the vibrating diaphragm 20 is applied to a sound emitting device. The sound emitting device can be a large loudspeaker, or a micro loudspeaker. The vibrating diaphragm 20 is part of a vibrating system. The vibrating diaphragm 20 is a folded ring vibrating diaphragm or a planar vibrating diaphragm. The vibrating diaphragm 20 comprises a butadiene styrene rubber layer. The vibrating diaphragm 20 has a single layer structure or a multi-layer structure. The butadiene styrene rubber layer is prepared from a blended material. The preparation method is, for example, mold pressing, air pressure forming, etc. The blended material is mixed from multiple materials, for example, multiple materials are added to a mixer. The blending is performed in the mixer, and the multiple materials are uniformly mixed to form the blended material.

[0037] The butadiene styrene copolymer (SBR) is a copolymer of styrene and butadiene prepared by emulsion polymerization or solution polymerization. The main chain of the butadiene styrene copolymer is a butadiene segment, and the butadiene segment has high flexibility. The side chain of the butadiene styrene copolymer contains styrene, and the styrene is a rigid group. The styrene can enhance the rigidity and heat resistance of the butadiene styrene rubber layer. The higher the mass percentage of styrene in the butadiene styrene copolymer, the higher the glass transition temperature of the butadiene styrene copolymer; otherwise, the lower. In the embodiment of the present application, the mass percentage of styrene in the first butadiene styrene copolymer is 8%-12%, and the mass percentage of styrene in the second butadiene styrene copolymer is 40%-50%, so that the glass transition temperature of the first butadiene styrene copolymer is lower, and the glass transition temperature of the second butadiene styrene copolymer is higher. That is, the blended material of the embodiment of the present application comprises the first butadiene styrene copolymer with low glass transition temperature and the second butadiene styrene copolymer with high glass transition temperature, and the glass transition temperature of the butadiene styrene rubber layer obtained after cross-linking reaction is -40℃ to 0℃. In this way, the damping temperature range of the butadiene styrene rubber layer can be effectively widened, so that the vibrating diaphragm has high damping performance in the temperature range of -60℃ to 20℃, and the loss factor of the vibrating diaphragm in the temperature range of -60℃ to 20℃ is ≥0.15.

[0038] In addition, in the embodiment of the present application, the mass percentage of the first butadiene-styrene copolymer in the blended material is 50%-80%, and the mass percentage of the second butadiene-styrene copolymer in the blended material is 20%-50%. The mass percentage of the first butadiene-styrene copolymer in the blended material is related to the elastic recovery rate and the loss factor of the diaphragm. When the mass percentage of the first butadiene-styrene copolymer in the blended material is less than 50%, the elastic recovery rate of the diaphragm under 10% tensile strain is too low, for example, less than 85%, and the THD distortion of the sound generating device using the diaphragm is high, and the sound quality is low. When the mass percentage of the first butadiene-styrene copolymer in the blended material is greater than 80%, it will cause the loss factor of the diaphragm in the glass transition temperature interval to be too low. When the mass percentage of the first butadiene-styrene copolymer in the blended material is 50%-80%, the diaphragm 20 has high damping performance while the elastic recovery rate remains at a relatively high level, the loss factor of the diaphragm in the temperature range of -60°C to 20°C is greater than or equal to 0.15, and the elastic recovery rate of the diaphragm under 10% tensile strain is greater than or equal to 85%. The THD distortion of the sound generating device using the diaphragm is small, and the sound quality is higher.

[0039] In addition, the ratio of the F0 of the diaphragm 20 at 23°C to the F0 at -20°C is greater than or equal to 0.2 and less than 1. The F0 of the diaphragm 20 at 23°C represents the size of the resonant frequency of the diaphragm 20 at room temperature. The F0 of the diaphragm 20 at -20°C represents the size of the resonant frequency of the diaphragm 20 at -20°C. The closer the ratio of the F0 of the diaphragm 20 at 23°C to the F0 at -20°C is to 1, the better the vibration stability of the diaphragm 20 at different temperatures. The ratio of the F0 of the diaphragm 20 at 23°C to the F0 at -20°C in the embodiment of the present application is greater than or equal to 0.2 and less than 1, which indicates that the vibration stability of the diaphragm 20 at different temperatures is better.

[0040] Alternatively, the ratio of the F0 of the diaphragm 20 at 23°C to the F0 at -20°C is 0.2, 0.22, 0.24, 0.26, 0.28, 0.3, 0.33, 0.35, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, etc. Those skilled in the art can select according to actual needs.

[0041] In the embodiment of the present application, the diaphragm 20 comprises a butadiene-styrene rubber layer prepared from a blended material. The blended material comprises a first butadiene-styrene copolymer with a low glass transition temperature and a second butadiene-styrene copolymer with a high glass transition temperature. The glass transition temperature of the butadiene-styrene rubber layer obtained after cross-linking reaction is -40℃ to 0℃. In this way, the damping temperature range of the butadiene-styrene rubber layer can be effectively widened, so that the diaphragm 20 has a high loss factor and good damping performance in the temperature range of -60℃ to 20℃. When the mass percentage of the first butadiene-styrene copolymer in the blended material is 50%-80%, the diaphragm has high damping performance while the elastic recovery rate remains at a high level. The loss factor of the diaphragm in the temperature range of -60℃ to 20℃ is ≥0.15, and the elastic recovery rate of the diaphragm under a tensile strain of 10% is ≥85%. The sound emitting device using the diaphragm has a small THD distortion and a higher sound quality. The ratio of F0 at 23℃ to F0 at -20℃ of the diaphragm 20 in the embodiment of the present application is greater than or equal to 0.2 and less than 1, indicating that the vibration stability of the diaphragm 20 at different temperatures is good.

[0042] In some specific embodiments of the present application, the molecular structure of the first butadiene-styrene copolymer and / or the second butadiene-styrene copolymer is as follows:

[0043] ,

[0044] wherein x, y, z are natural numbers.

[0045] In this embodiment, the first butadiene-styrene copolymer and / or the second butadiene-styrene copolymer is of the above formula. According to the mass percentage of styrene in the butadiene-styrene copolymer, appropriate first butadiene-styrene copolymer and second butadiene-styrene copolymer are selected.

[0046] In some specific embodiments of the present application, the glass transition temperature of the first butadiene-styrene copolymer is -60℃ to -50℃, and the glass transition temperature of the second butadiene-styrene copolymer is -20℃ to 5℃.

[0047] In this embodiment, the glass transition temperature of the first butadiene-styrene copolymer is -60℃ to -50℃, which can effectively widen the low-temperature damping temperature range of the diaphragm. The glass transition temperature of the second butadiene-styrene copolymer is -20℃ to 5℃, which can effectively widen the high-temperature damping temperature range of the diaphragm. Finally, the glass transition temperature of the butadiene-styrene rubber layer is -40℃ to 0℃, and the diaphragm has a high loss factor and elastic recovery rate in the temperature range of -60℃ to 20℃, and good vibration stability. The sound emitting device using the diaphragm has a small THD distortion and a higher sound quality.

[0048] Optionally, the first butadiene-styrene copolymer has a glass transition temperature of -60℃, -55℃, -50℃, etc., and the second butadiene-styrene copolymer has a glass transition temperature of -20℃, -15℃, -10℃, -5℃, 0℃, 5℃, etc., which can be set according to actual needs by those skilled in the art.

[0049] In some embodiments of the present application, the blended material further comprises a filler, the filler comprising at least one of silica, carbon black, mineral whisker, talc powder, diatomite, calcium carbonate, graphite, clay, mica; the mass percentage of the filler in the blended material is 30%-60%.

[0050] In this embodiment, the filler is used to improve the mechanical properties of the diaphragm 20, such as tensile strength, hardness, etc. In the preparation of the diaphragm 20, the filler can use one or a mixture of more than one of silica, carbon black, mineral whisker, talc powder, diatomite, calcium carbonate, graphite, clay, mica.

[0051] When the ingredients are mixed, the mass percentage of the filler in the blended material is 30wt%-60wt%.

[0052] It should be noted that the lower the content of the filler, the lower the tensile strength of the diaphragm 20, especially when the mass percentage of the filler in the blended material is less than 30wt%, the reinforcing effect on the diaphragm 20 is poor. If the content of the filler is too high, for example, when the mass percentage of the filler in the blended material is greater than 60wt%, the elongation at break of the diaphragm 20 will decrease significantly, the toughness of the material is insufficient, which leads to the diaphragm 20 prone to membrane rupture during vibration. When the mass percentage of the filler in the blended material is 30wt%-60wt%, the diaphragm 20 has sufficient tensile strength, elongation at break and toughness.

[0053] In some embodiments of the present application, the blended material further comprises a vulcanizing agent, the vulcanizing agent comprising at least one of a sulfur system and a peroxide system, the mass percentage of the vulcanizing agent in the blended material is 0.5%-3%.

[0054] In this embodiment, a vulcanizing agent is added to the blended material. The vulcanizing agent is used to cause the butadiene-styrene copolymer to undergo crosslinking reaction, thereby forming a network structure.

[0055] It should be noted that the mass of the vulcanizing agent accounts for 0.5wt%-3wt% of the total mass of the blended material during compounding. It should be noted that the less the mass content of the vulcanizing agent, the less the cross-linking degree of the blended material, the looser the network structure formed by the blended material, and the poorer the stability. When the mass of the vulcanizing agent in the blended material is less than 0.5wt%, the cross-linking degree of the diaphragm 20 is insufficient, the network structure has poor stability, the tensile strength and elastic modulus of the material are low, the temperature resistance is poor, the service life is short, and permanent deformation is prone to occur. When the mass of the vulcanizing agent in the blended material is greater than 3wt%, the cross-linking degree of the material is too high and uneven, which can form a local rigid area, resulting in poor material uniformity, poor tensile strength and tear strength, increased glass transition temperature, and significantly reduced elastic recovery rate, and the product is prone to membrane rupture. When the mass content of the vulcanizing agent in the blended material is 0.5wt%-3wt%, the diaphragm 20 can have a suitable cross-linking degree, and the diaphragm 20 can have a suitable tensile strength, elastic modulus, high tensile strength and tear strength, a moderate glass transition temperature, and an elastic recovery rate, and is not prone to membrane rupture.

[0056] Optionally, the mass of the vulcanizing agent in the blended material is 0.5wt%, 1wt%, 2wt%, 3wt%, etc. Further, the mass of the vulcanizing agent in the blended material is 1wt%-2wt%. Those skilled in the art can select according to actual needs.

[0057] Optionally, the vulcanizing agent includes a sulfur system, and the sulfur system includes at least one of sulfur, a sulfenamide amine accelerator, a thiuram accelerator, zinc oxide, and stearic acid.

[0058] And / or, the vulcanizing agent includes a peroxide system, and the peroxide system includes at least one of dicumyl peroxide, dibenzoyl peroxide, tert-butyl peroxybenzoate, dilauroyl peroxide, 2,5-dimethyl-2,5-bis(tert-butyl peroxy) hexane, and cumene hydroperoxide.

[0059] That is, when selecting the vulcanizing agent, one or more mixtures of sulfur, sulfenamide amine accelerator, thiuram accelerator, zinc oxide, and stearic acid can be selected.

[0060] Alternatively, one or more mixtures of dicumyl peroxide, dibenzoyl peroxide, tert-butyl peroxybenzoate, dilauroyl peroxide, 2,5-dimethyl-2,5-bis(tert-butyl peroxy) hexane, and cumene hydroperoxide can be selected.

[0061] It can also be a mixture of various of sulfur, sulfenamide accelerator, thiuram accelerator, zinc oxide, stearic acid, dicumyl peroxide, dibenzoyl peroxide, t-butyl peroxybenzoate, dilauroyl peroxide, 2,5-dimethyl-2,5-bis(t-butylperoxy)hexane, cumene hydroperoxide.

[0062] The above vulcanizing agents can all cause the cross-linking reaction of the butadiene-styrene copolymer, thereby forming a network structure.

[0063] In some embodiments of the present application, the blended material further comprises an accelerator, the accelerator comprising at least one of tetramethylthiuram disulfide, tetraethylthiuram disulfide, 2-mercaptobenzothiazole, dibenzothiazyl disulfide, N-cyclohexyl-2-benzothiazole sulfenamide, N-t-butyl-2-benzothiazole sulfenamide, zinc dimethyl dithiocarbamate, diphenyl guanidine, sulfenamide accelerator, thiuram accelerator, zinc oxide, stearic acid; the mass percentage of the accelerator in the blended material being 0.2%-2%.

[0064] In this embodiment, the accelerator can accelerate the vulcanization speed, shorten the vulcanization time, and reduce the vulcanization temperature, thereby reducing the amount of vulcanizing agent. One or more of tetramethylthiuram disulfide, tetraethylthiuram disulfide, 2-mercaptobenzothiazole, dibenzothiazyl disulfide, N-cyclohexyl-2-benzothiazole sulfenamide, N-t-butyl-2-benzothiazole sulfenamide, zinc dimethyl dithiocarbamate, diphenyl guanidine, sulfenamide accelerator, thiuram accelerator, zinc oxide, stearic acid can be added to the blended material as the accelerator.

[0065] When the blended material is prepared, the mass percentage of the accelerator in the blended material is 0.2%-2%. It needs to be noted that when the amount of the accelerator added to the blended material is less than 0.2%, the accelerator does not have obvious effect of accelerating the vulcanization speed, shortening the vulcanization time, and reducing the vulcanization temperature. When the amount of the accelerator added to the blended material is greater than 2%, the vulcanization speed is too fast, which can easily cause the network structure of the rubber molecules to be non-uniform, and the diaphragm 20 can be easily broken. When the mass percentage of the accelerator in the blended material is 0.2%-2%, the vulcanization speed of the blended material is moderate.

[0066] Optionally, the mass percentage of the accelerator in the blended material is 0.2%, 1%, 1.5%, 2%, etc., which can be set according to actual needs by those skilled in the art.

[0067] In some embodiments of the present application, the blended material further comprises an antioxidant, the antioxidant comprises at least one of N-isopropyl-N'-phenyl-p-phenylenediamine, N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine, N,N'-diphenyl-p-phenylenediamine, N-phenyl-β-naphthylamine, 2,6-di-tert-butyl-p-cresol, 2,2'-methylenebis(4-methyl-6-tert-butylphenol), 2,2,4-trimethyl-1,2-dihydroquinoline, 2-mercaptobenzimidazole, 6-ethoxy-2,2,4-trimethyl-1,2-dihydroquinoline; the mass percentage of the antioxidant in the blended material is 0.5%-4%.

[0068] During the use of the polymer material, with the extension of time, the molecular chain breaks to produce autocatalytic active free radicals. The autocatalytic active free radicals can accelerate the aging of the polymer material itself. The addition of the antioxidant in the diaphragm 20 can stop the production of autocatalytic active free radicals in the blended material, thereby delaying the aging of the blended material and prolonging the service life of the diaphragm 20. When preparing the diaphragm 20, one or more mixtures of N-isopropyl-N'-phenyl-p-phenylenediamine, N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine, N,N'-diphenyl-p-phenylenediamine, N-phenyl-β-naphthylamine, 2,6-di-tert-butyl-p-cresol, 2,2'-methylenebis(4-methyl-6-tert-butylphenol), 2,2,4-trimethyl-1,2-dihydroquinoline, 2-mercaptobenzimidazole, 6-ethoxy-2,2,4-trimethyl-1,2-dihydroquinoline can be selected as the antioxidant. The above-mentioned antioxidants can be mutually soluble with the styrene-butadiene copolymer, thereby preventing the aging of the diaphragm 20 and prolonging the service life of the diaphragm 20.

[0069] When the ingredients are prepared, the mass percentage of the antioxidant in the blended material is 0.5wt%-4wt%.

[0070] It should be noted that, in the blended material, if the amount of the antioxidant is too small, for example, when the mass percentage of the antioxidant in the blended material is less than 0.5wt%, the effect of preventing the aging of the diaphragm 20 and prolonging the service life of the diaphragm 20 cannot be achieved. If the amount of the antioxidant is too large, for example, when the mass percentage of the antioxidant in the blended material is greater than 4wt%, the antioxidant cannot be well mutually soluble with the styrene-butadiene copolymer, so that the antioxidant cannot be uniformly dispersed in the blended material, resulting in the decrease of the mechanical properties of the diaphragm 20. When the mass percentage of the antioxidant in the blended material is 0.5wt%-4wt%, the antioxidant can effectively prolong the service life of the diaphragm 20, and the antioxidant can be uniformly dispersed in the blended material, so that the prepared diaphragm 20 can maintain good mechanical properties.

[0071] Optionally, the mass percentage of the anti-aging agent in the blended material is 0.5 wt%, 1 wt%, 2 wt%, 3 wt%, 4 wt%, etc. Further, the mass percentage of the anti-aging agent in the blended material is 2 wt%-3 wt%. Of course, the mass percentage of the anti-aging agent in the blended material is not limited to the above embodiments, and those skilled in the art can select it according to actual needs.

[0072] In some embodiments of the present application, the diaphragm 20 is formed as a single-layer structure, and the diaphragm 20 is composed of one layer of the butadiene-styrene rubber layer;

[0073] Or, the diaphragm 20 is formed as a multi-layer structure, and the diaphragm 20 includes at least one butadiene-styrene rubber layer and a composite layer, the composite layer is arranged in a stack with the butadiene-styrene rubber layer, and the composite layer is at least one of an elastomer layer, an engineering plastic layer, and a film layer.

[0074] That is, the diaphragm 20 of the embodiment of the present application can be a butadiene-styrene rubber layer with a single-layer structure. The diaphragm 20 has a simple structure and a simple preparation process.

[0075] Alternatively, the diaphragm 20 is a multi-layer structure. That is, at least one butadiene-styrene rubber layer is stacked with a composite layer to form a diaphragm 20 with a multi-layer structure. The composite layer is at least one of an elastomer layer, an engineering plastic layer, and a film layer. The number of layers of the multi-layer structure is 2, 3, 4, 5, 6, 7, etc.

[0076] Optionally, the elastomer layer includes one or more of thermoplastic polyurethane elastomer, thermoplastic polyester elastomer, thermoplastic polyamide elastomer, and thermoplastic polystyrene elastomer. The engineering plastic layer includes one or more of PEEK, PAR, PMI, PET, PEN, PA, PEI, and LCP. The film layer is a silicone film and / or an acrylic film. The composite layer is one layer or multiple layers.

[0077] According to another embodiment of the present application, a sound generating device is provided. As shown in Figures 2-4 The sound generating device 100 includes the diaphragm 20 of the above-mentioned embodiments.

[0078] As shown in Figures 2-3 The sound generating device 100 is a micro speaker. The sound generating device 100 can include a housing 10, a magnetic circuit system, and a vibration system. The magnetic circuit system includes a permanent magnet 40 for forming a magnetic gap. The vibration system includes a diaphragm 20 and a voice coil 30. The diaphragm 20 and the permanent magnet 40 are both connected with the housing 10. The permanent magnet 40 is arranged on one side of the diaphragm 20 along the thickness direction. One end of the voice coil 30 is connected with the diaphragm 20, and the other end is located in the magnetic gap.

[0079] In this example, the diaphragm 20 can be a folded ring diaphragm. The folded ring diaphragm includes a center portion, a folded ring portion, and a fixed portion connected in sequence from inside to outside. The fixed portion is used to connect with the shell 10. The center portion is provided with a dome, and the voice coil 30 is connected with the center portion or the dome.

[0080] Figure 4 Another sound generating device 100 of an embodiment of the present application is shown. The sound generating device is a large loudspeaker.

[0081] The sound generating device 100 can include a shell 10, a magnetic circuit system including a permanent magnet 40 and a U-shaped iron 90 for forming a magnetic gap, and a vibration system including a diaphragm 20, a cone 50, a skeleton 80, a voice coil 30, and a dust cover 60. The inner edge of the cone 50 is connected to one end of the skeleton 80. The dust cover 60 is provided on one end of the skeleton 80. The voice coil 30 is provided around the other end of the skeleton 80. The diaphragm 20 is connected to the outer edge of the cone 50. The diaphragm 20 and the permanent magnet 40 are both connected with the shell 10. The permanent magnet 40 is provided on one side of the diaphragm 20 along the thickness direction. One end of the voice coil 30 is located in the magnetic gap. The shell 10 is provided with a spring 70. The spring 70 is connected to the middle portion of the skeleton 80.

[0082] In this example, the diaphragm 20 can be a folded ring diaphragm. The folded ring diaphragm includes a center portion, a folded ring portion, and a fixed portion connected in sequence from inside to outside. The fixed portion is used to connect with the shell 10. The center portion is provided with a dome, and the voice coil 30 is connected with the center portion or the dome.

[0083] In other examples, the diaphragm 20 can also be a planar diaphragm or the like structure, which can be determined by those skilled in the art according to actual conditions, and is not specifically limited here.

[0084] In other examples, the diaphragm 20 can also be a planar diaphragm or the like structure, which can be determined by those skilled in the art according to actual conditions, and is not specifically limited here.

[0085] According to still another embodiment of the present application, an electronic device is provided.

[0086] The electronic device is, for example, a mobile phone, a computer, a television, a sound box, a walkie-talkie, a VR device, an AR device, smart glasses, etc. The electronic device includes the sound generating device 100 described in the above embodiments. Of course, the electronic device of the present application also includes at least all the beneficial effects of the above embodiments, which are not described here.

[0087] The diaphragm 20 and the sound generating device 100 of the present application will be described in detail below in conjunction with specific embodiments. It should be noted that the following description is only exemplary and is not a specific limitation on the present application.

[0088] (1) Glass transition temperature, loss factor, and elastic recovery rate of the butadiene-styrene rubber layer with different component contents

[0089] The diaphragm samples were prepared by blending the first and second butadiene-styrene copolymers in different mass percentages. The glass transition temperature, the loss factor in the temperature range of -60℃ to 20℃, and the elastic recovery rate under 10% tensile strain of the diaphragm samples were tested, respectively. The thickness of the diaphragm samples was 100 μm, and the samples were prepared by compression molding.

[0090] The glass transition temperature was tested by a differential scanning calorimeter according to the standard GB / T 19466.1-2004, the starting temperature was -100℃, the ending temperature was 100℃, and the temperature rate was 20℃ / min.

[0091] The loss factor was tested by a DMA dynamic mechanical analyzer. The test standard was ASTM D5026-23. The test conditions were: tensile mode, temperature: -60~100℃, heating rate 3℃ / min, strain 0.2%, and frequency 1Hz. The loss factor of the diaphragm samples at different temperatures was obtained, and the maximum and minimum values were taken as the end point values of the loss factor interval.

[0092] The elastic recovery rate under 10% tensile strain was tested according to the test standard ASTM D5026-23. The test conditions were: tensile mode, temperature: 23℃, strain: 10%, holding time: 5min, relaxation time: 10min, and recovery time: 5min.

[0093] The content of the components in the blended material and the test results are shown in Table 1.

[0094] Table 1-Test results of the components of the blended material and the diaphragm samples

[0095]

[0096] As can be seen from Table 1, as the mass percentage of the first butadiene-styrene copolymer in the blended material decreases and the mass percentage of the second butadiene-styrene copolymer increases, the glass transition temperature of the diaphragm gradually increases, the loss factor in the temperature range of -60℃ to 20℃ gradually increases as a whole, and the elastic recovery rate under 10% tensile strain gradually decreases. This is mainly because the mass percentage of styrene in the second butadiene-styrene copolymer is higher than that in the first butadiene-styrene copolymer. The higher the mass percentage of styrene in the butadiene-styrene copolymer, the higher the glass transition temperature and the loss factor of the butadiene-styrene copolymer; otherwise, the lower the glass transition temperature and the loss factor. As the mass percentage of the second butadiene-styrene copolymer in the blended material increases, the mass percentage of styrene in the butadiene-styrene rubber layer gradually increases, so the glass transition temperature and the loss factor of the diaphragm gradually increase.

[0097] (2) Performance comparison of the examples and comparative examples

[0098] Examples:

[0099] The diaphragm 20 is a single-layered folded ring diaphragm. The thickness of the diaphragm 20 is 110 μm. The diaphragm 20 is prepared by compression molding of a butadiene-styrene rubber. The butadiene-styrene rubber is prepared from a blend material including a first butadiene-styrene copolymer and a second butadiene-styrene copolymer. The first butadiene-styrene copolymer has a styrene content of 10% by mass and a glass transition temperature of -52 °C. The second butadiene-styrene copolymer has a styrene content of 45% by mass and a glass transition temperature of -3 °C. The specific formulation of the blend material is shown in Table 2.

[0100] Comparative Examples:

[0101] The diaphragm 20 is a single-layered folded ring diaphragm. The thickness of the diaphragm 20 is 110 μm. The diaphragm 20 is prepared by compression molding of a butadiene-styrene rubber. The butadiene-styrene rubber has a glass transition temperature of -42 °C. The specific formulation of the material is shown in Table 2.

[0102] Table 2 - Formulation of the diaphragm 20 of the examples and comparative examples

[0103]

[0104] Performance tests:

[0105] (1) The hardness (Shore A), glass transition temperature, loss factor (-60 °C to 10 °C, minimum value), and elastic recovery at 10% tensile strain of the diaphragm 20 of the examples and comparative examples were tested, respectively. It should be noted that, due to the difference between the size of the diaphragm 20 and the sample size required by the corresponding test standard, a sample having the same composition as the diaphragm 20 was selected for the relevant tests to represent the characteristics of the diaphragm 20. Since the sample has the same composition as the diaphragm 20, the relevant characteristics of the sample are consistent with those of the diaphragm 20.

[0106] The hardness (Shore A) and the elastic recovery at 10% tensile strain were tested according to the ASTM-D882 standard, and the test temperature was 23 °C.

[0107] The test methods for the loss factor and the glass transition temperature are as described above.

[0108] (2) The diaphragm 20 of the examples and comparative examples was assembled into sound generating devices. The two diaphragms 20 have the same size. The THD curves of the two sound generating devices were tested. Details are shown in Figure 5 .

[0109] Results and analysis:

[0110] (1) The results of the hardness (Shore A), glass transition temperature, loss factor (-60℃ to 10℃, taking the minimum value), and elastic recovery rate at 10% tensile strain of the diaphragms 20 of the examples and the comparative examples are shown in Table 3.

[0111] Table 3 - Performance test of the diaphragms 20 of the examples and the comparative examples

[0112]

[0113] As can be seen from Table 3, the hardness of the diaphragm 20 of the example is the same as that of the diaphragm 20 of the comparative example, and the glass transition temperature of the diaphragm 20 of the example is higher than that of the diaphragm 20 of the comparative example. This is because the blending material of the example diaphragm includes the first butadiene-styrene copolymer with a low glass transition temperature and the second butadiene-styrene copolymer with a high glass transition temperature. The second butadiene-styrene copolymer with a high glass transition temperature can expand the glass transition temperature of the diaphragm to the high temperature zone, so that the glass transition temperature of the diaphragm 20 of the example is higher than that of the diaphragm 20 of the comparative example.

[0114] The loss factor and the elastic recovery rate at 10% tensile strain of the diaphragm 20 of the example are both higher than those of the diaphragm 20 of the comparative example. This is mainly because the blending material of the example includes the first butadiene-styrene copolymer with a low glass transition temperature and the second butadiene-styrene copolymer with a high glass transition temperature, and the glass transition temperature of the butadiene-styrene rubber layer obtained after cross-linking reaction is -25℃, thereby effectively widening the damping temperature range of the butadiene-styrene rubber layer, so that the diaphragm of the example has a high loss factor in the temperature range of -60℃ to 20℃. When the mass percentage content of the first butadiene-styrene copolymer in the blending material is 60%, the diaphragm of the example has both a high elastic recovery rate and a loss factor.

[0115] (2) As can be seen from Table 4, in the range of 100Hz-600Hz, the THD curve of the sound production device of the example is below the THD curve of the sound production device of the comparative example. In the range above 600Hz, the difference between the THD curve of the sound production device of the example and the THD curve of the sound production device of the comparative example is small. This is mainly because the blending material of the example includes the first butadiene-styrene copolymer with a low glass transition temperature and the second butadiene-styrene copolymer with a high glass transition temperature, and the glass transition temperature of the butadiene-styrene rubber layer obtained after cross-linking reaction is -25℃, thereby effectively widening the damping temperature range of the butadiene-styrene rubber layer, so that the diaphragm of the example has a high loss factor in the temperature range of -60℃ to 20℃. When the mass percentage content of the first butadiene-styrene copolymer in the blending material is 60%, the diaphragm of the example has both a high elastic recovery rate and a loss factor, which can effectively reduce the THD of the sound production device using the diaphragm 20, and has a higher sound quality. Figure 5 As can be seen from Table 4, in the range of 100Hz-600Hz, the THD curve of the sound production device of the example is below the THD curve of the sound production device of the comparative example. In the range above 600Hz, the difference between the THD curve of the sound production device of the example and the THD curve of the sound production device of the comparative example is small. This is mainly because the blending material of the example includes the first butadiene-styrene copolymer with a low glass transition temperature and the second butadiene-styrene copolymer with a high glass transition temperature, and the glass transition temperature of the butadiene-styrene rubber layer obtained after cross-linking reaction is -25℃, thereby effectively widening the damping temperature range of the butadiene-styrene rubber layer, so that the diaphragm of the example has a high loss factor in the temperature range of -60℃ to 20℃. When the mass percentage content of the first butadiene-styrene copolymer in the blending material is 60%, the diaphragm of the example has both a high elastic recovery rate and a loss factor, which can effectively reduce the THD of the sound production device using the diaphragm 20, and has a higher sound quality.

[0116] The differences between the various embodiments are mainly described in the above embodiments. The optimization features different between the various embodiments can be combined to form a better embodiment as long as they are not contradictory. For the sake of brevity, they will not be described herein.

[0117] Although some specific embodiments of the present application have been described in detail by way of example with reference to the drawings, it is to be understood that the above examples are intended to be illustrative only and the application is not limited to those examples. It will be apparent to those skilled in the art that various modifications, additions and substitutions can be made without departing from the scope and spirit of the application as defined in the accompanying claims. The scope of the present application is defined by the appended claims.

Claims

1. A diaphragm for a sound-generating device, characterized in that, The diaphragm includes a styrene-butadiene rubber layer, which is prepared from a blend of materials. The blend includes a first styrene-butadiene copolymer and a second styrene-butadiene copolymer. The first styrene-butadiene copolymer contains 8%-12% styrene by mass, the second styrene-butadiene copolymer contains 40%-50% styrene by mass, the first styrene-butadiene copolymer contains 50%-80% styrene by mass, and the second styrene-butadiene copolymer contains 20%-50% styrene by mass in the blend. The glass transition temperature of the styrene-butadiene rubber layer is -40°C to 0°C. The ratio of the diaphragm's glass transition factor (F0) at 23°C to its glass transition factor (F0) at -20°C is greater than or equal to 0.2 and less than 1. The loss factor of the diaphragm is ≥0.15 in the temperature range of -60°C to 20°C. The elastic recovery rate of the diaphragm under 10% tensile strain is ≥85%. The glass transition temperature of the first styrene-butadiene copolymer is -60°C to -50°C, and the glass transition temperature of the second styrene-butadiene copolymer is -20°C to 5°C.

2. The diaphragm according to claim 1, characterized in that, The molecular structures of the first styrene-butadiene copolymer and / or the second styrene-butadiene copolymer are as follows: ， Where x, y, and z are natural numbers.

3. The diaphragm according to claim 1, characterized in that, The blended material further includes fillers, which include at least one of silicon dioxide, carbon black, mineral whiskers, talc, diatomaceous earth, calcium carbonate, graphite, clay, and mica; the filler has a mass percentage of 30%-60% in the blended material.

4. The diaphragm according to claim 1, characterized in that, The blended material further includes a vulcanizing agent, which includes at least one of a sulfur system and a peroxide system, and the mass percentage of the vulcanizing agent in the blended material is 0.5%-3%.

5. The diaphragm according to claim 4, characterized in that, The vulcanizing agent includes a sulfur system, which includes at least one of sulfur, sulfenic acid accelerator, thiuram accelerator, zinc oxide, and stearic acid. And / or, the vulcanizing agent comprises a peroxide system, the peroxide system comprising at least one of dicumyl peroxide, benzoyl peroxide, tert-butyl peroxide, dilauroyl peroxide, 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane, and cumyl hydroperoxide.

6. The diaphragm according to claim 1, characterized in that, The blend material further includes an accelerator, which includes at least one of tetramethylthiuram disulfide, tetraethylthiuram disulfide, 2-mercaptobenzothiazole, dibenzothiazole disulfide, N-cyclohexyl-2-benzothiazole sulfenamide, N-tert-butyl-2-benzothiazole sulfenamide, zinc dimethyl dithiocarbamate, diphenylguanidine, sulfenic acid accelerator, thiuram accelerator, zinc oxide, and stearic acid; the accelerator has a mass percentage content of 0.2%-2% in the blend material.

7. The diaphragm according to claim 1, characterized in that, The blend material further includes an antioxidant, which includes at least one selected from N-isopropyl-N'-phenyl-p-phenylenediamine, N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine, N,N'-diaryl-p-phenylenediamine, N-phenyl-β-naphthylamine, 2,6-di-tert-butyl-p-cresol, 2,2'-methylenebis(4-methyl-6-tert-butylphenol), 2,2,4-trimethyl-1,2-dihydroquinoline, 2-mercaptobenzimidazole, and 6-ethoxy-2,2,4-trimethyl-1,2-dihydroquinoline; the antioxidant is present in the blend material at a mass percentage of 0.5%-4%.

8. The diaphragm according to claim 1, characterized in that, The diaphragm is formed as a single-layer structure, and the diaphragm is composed of a single layer of styrene-butadiene rubber; Alternatively, the diaphragm may be formed as a multilayer structure, comprising at least one layer of the styrene-butadiene rubber and a composite layer, wherein the composite layer is stacked with the styrene-butadiene rubber layer, and the composite layer is at least one of an elastomer layer, an engineering plastic layer, and a film layer.

9. A sound-generating device, characterized in that, Includes the diaphragm as described in any one of claims 1-8.

10. An electronic device, characterized in that, Includes the sound-generating device as described in claim 9.

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