Vibrating diaphragm for sound production device, sound production device and electronic equipment

Abstract

The invention discloses a vibrating diaphragm for a sound production device, the sound production device and electronic equipment. The vibrating diaphragm comprises a modified polyisoprene rubber layer, the modified polyisoprene rubber layer is prepared from a blending material, and the blending material comprises polyisoprene rubber and a damping modifier; the mass percentage of the polyisoprene rubber in the blended material is greater than or equal to 45%; the damping modifier comprises at least one of a butadiene-acrylonitrile copolymer, a hydrogenated butadiene-acrylonitrile copolymer, an ethylene-vinyl acetate copolymer and an acrylate homopolymer, the modified polyisoprene rubber layer has a first glass transition temperature and a second glass transition temperature, the first glass transition temperature ranges from-70 DEG C to-50 DEG C, and the second glass transition temperature ranges from-70 DEG C to-50 DEG C; the second glass transition temperature is from-40 DEG C to-5 DEG C. The vibrating diaphragm provided by the embodiment of the invention has two glass transition temperature regions within the temperature range of-70 DEG C to 10 DEG C, so that the vibrating diaphragm has good damping performance, the THD of the sound production device is effectively reduced, and the listening yield is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of electroacoustic conversion, and more particularly to a diaphragm for a sound-generating device, a sound-generating device, and an electronic device. Background Art

[0002] In related technology, large speakers typically use polyisoprene rubber as their diaphragm. The diaphragm material's elastic modulus is insufficiently stable, resulting in significant variations in the speaker's F0 at different temperatures and poor acoustic performance stability. Furthermore, at lower temperatures, such as between -30°C and 10°C, the diaphragm material's rigidity increases, and the damping loss factor is low in some temperature ranges, leading to high THD distortion and poor listening performance. At even lower temperatures, such as between -70°C and 10°C, the diaphragm's elastic modulus changes significantly, causing the product's F0 to fluctuate significantly. Summary of the Invention

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

[0004] According to a first aspect of the present invention, a diaphragm for a sound-generating device is provided. The diaphragm includes a modified polyisoprene rubber layer, wherein the modified polyisoprene rubber layer is prepared from a blended material including polyisoprene rubber and a damping modifier; the mass percentage of the polyisoprene rubber in the blended material is ≥ 45%; The damping modifier includes at least one of butadiene-acrylonitrile copolymer, hydrogenated butadiene-acrylonitrile copolymer, ethylene-vinyl acetate copolymer, and acrylate homopolymer, and the mass percentage of the damping modifier in the blended material is ≤25%; The modified polyisoprene rubber layer has a first glass transition temperature and a second glass transition temperature, the first glass transition temperature is between -70°C and -50°C, the second glass transition temperature is between -40°C and -5°C, the ratio of F0 of the modified polyisoprene rubber layer at 23°C to F0 at -40°C is greater than or equal to 0.70 and less than 1, and the dissipation factor of the modified polyisoprene rubber layer in the range of -70°C to 10°C is ≥0.15.

[0005] Optionally, the polyisoprene rubber has a glass transition temperature of -70°C to -50°C; And / or, the glass transition temperature of the damping modifier is -40°C to -5°C.

[0006] Optionally, the polyisoprene rubber includes isoprene homopolymer, and the molecular structure of the isoprene homopolymer is: , Wherein, a, b, and c are integers and cannot be 0 at the same time.

[0007] Optionally, the damping modifier includes a butadiene-acrylonitrile copolymer, and the molecular structure of the butadiene-acrylonitrile copolymer is: , Wherein, d and e are integers and cannot be 0 at the same time; f is a natural number; And / or, the damping modifier includes a hydrogenated butadiene-acrylonitrile copolymer, and the molecular structure of the hydrogenated butadiene-acrylonitrile copolymer is:

[0008] Wherein, g and h are integers and cannot be 0 at the same time; i is a natural number; j and k are integers and cannot be 0 at the same time; And / or, the damping modifier comprises ethylene-vinyl acetate copolymer, and the molecular structure of the ethylene-vinyl acetate copolymer is: , Among them, m and n are natural numbers; And / or, the damping modifier comprises an acrylate homopolymer, and the molecular structure of the acrylate homopolymer is: , Among them, r, s, and t are integers and cannot be 0 at the same time; R1, R2, and R3 are any one of methyl, ethyl, propyl, butyl, and 2-ethylhexyl.

[0009] Optionally, the blended material further includes a filler, which includes at least one of silica, carbon black, mineral whiskers, talc, diatomaceous earth, calcium carbonate, kaolin, carbon nanotubes, graphene, clay, and mica, and the mass percentage of the filler in the blended material is 25%-50%.

[0010] Optionally, the blended material further includes a vulcanizing agent, the vulcanizing agent includes sulfur, and the mass percentage of the sulfur in the blended material is 0.2%-2.5%.

[0011] Optionally, the blended material further includes a vulcanizing agent, which includes: at least one of 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane, tert-butyl isopropyl benzene peroxide, 4,4-bis(tert-butylperoxy) butyl valerate, 1,1-bis(tert-butylperoxy)-3,3,5-trimethylcyclohexane, diisopropyl benzene peroxide, dibenzoyl peroxide, and tert-butyl perbenzoate; the mass percentage of the vulcanizing agent in the blended material is 0.4%-2.5%.

[0012] Optionally, 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, sulfenic acid amine accelerator, thiuram accelerator, zinc oxide, and stearic acid, and the mass percentage of the accelerator in the blend material is 0.3%-4.5%.

[0013] Optionally, the blended material further includes an antioxidant, which includes at least one of N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine, N,N'-diaryl-p-phenylenediamine, 2,6-di-tert-butyl-p-cresol, 2,2'-methylenebis(4-methyl-6-tert-butylphenol), 2,2,4-trimethyl-1,2-dihydroquinoline, and 6-ethoxy-2,2,4-trimethyl-1,2-dihydroquinoline; the mass percentage of the antioxidant in the blended material is 0.3%-3.5%.

[0014] Optionally, the tensile strength of the modified polyisoprene rubber layer is ≥12 MPa.

[0015] Optionally, the diaphragm is formed into a single-layer structure, and the diaphragm is composed of a layer of the modified polyisoprene rubber; Alternatively, the diaphragm is formed into a composite layer structure, the diaphragm includes at least one layer of the modified polyisoprene rubber layer and a composite layer, the composite layer and the modified polyisoprene rubber layer are stacked, and the composite layer is at least one of an elastomer layer, an engineering plastic layer and a film layer.

[0016] Optionally, the mass percentage of the polyisoprene rubber in the blended material is 45%-70%.

[0017] According to a second aspect of the present invention, a sound-generating device is provided, which includes the diaphragm of the present invention.

[0018] According to a third aspect of the present invention, an electronic device is provided, which includes the sound-generating device of the present invention.

[0019] In an embodiment of the present invention, the diaphragm includes a modified polyisoprene rubber layer, and the modified polyisoprene rubber is prepared from a blended material, wherein the blended material includes polyisoprene rubber and a damping modifier. In an embodiment of the present invention, a damping modifier is added to the polyisoprene rubber so that the prepared modified polyisoprene rubber has two different glass transition temperatures, namely a first glass transition temperature and a second glass transition temperature. The first glass transition temperature is from -70°C to -50°C, and the second glass transition temperature is from -40°C to -5°C. Therefore, the modified polyisoprene rubber of the embodiment of the present invention has two glass transition temperature regions within the temperature range of -70°C to -5°C, so that the diaphragm maintains a high loss factor within the temperature range of -70~10°C. The loss factor of the diaphragm within the temperature range of -70°C to 10°C is ≥0.15, which can effectively reduce the THD of the sound-generating device and improve the listening yield of the product. Furthermore, because the diaphragm has two glass transition temperature regions, the elastic modulus of the diaphragm changes smoothly within this temperature range, avoiding large fluctuations in F0 caused by drastic changes in the elastic modulus. The ratio of the diaphragm's F0 at 23°C to its F0 at -40°C is greater than or equal to 0.70 and less than 1, demonstrating that the diaphragm 20 exhibits excellent vibration stability across various temperatures.

[0020] Further features and advantages of the present invention will become apparent from the following detailed description of exemplary embodiments of the present invention with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

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

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

[0023] Figure 2 is a perspective view of a micro-speaker according to an embodiment of the present invention.

[0024] Figure 3 is a cross-sectional view of a microspeaker according to an embodiment of the present invention.

[0025] Figure 4 is a cross-sectional view of a large speaker according to an embodiment of the present invention.

[0026] Figure 5 3 are total harmonic distortion (THD) curves of the sound-generating devices of the embodiment of the present invention and the comparative example.

[0027] Reference numerals: 100. Sound-generating device; 10. Shell; 20. Diaphragm; 30. Voice coil; 40. Permanent magnet; 50. Cone; 60. Dust cover; 70. Damper; 80. Skeleton; 90. U iron. DETAILED DESCRIPTION

[0028] 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 of components and steps, numerical expressions and numerical values ​​set forth in these embodiments do not limit the scope of the present invention.

[0029] The following description of at least one exemplary embodiment is merely illustrative in nature and is in no way intended to limit the invention, its application, or uses.

[0030] Technologies, methods, and equipment known to ordinary technicians in the relevant art may not be discussed in detail, but where appropriate, the technologies, methods, and equipment should be considered part of the specification.

[0031] In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not limiting. Therefore, other examples of the exemplary embodiments may have different values.

[0032] It should be noted that like reference numerals and letters refer to like items in the following figures, and therefore, once an item is defined in one figure, it need not be further discussed in subsequent figures.

[0033] The following describes in detail the diaphragm 20 for a sound-generating device according to an embodiment of the present invention with reference to the accompanying drawings.

[0034] According to one embodiment of the present invention, a diaphragm 20 for a sound-generating device is provided. The diaphragm 20 includes a modified polyisoprene rubber layer, which is prepared from a blended material comprising polyisoprene rubber and a damping modifier; the mass percentage of the polyisoprene rubber in the blended material is ≥ 45%; The damping modifier includes at least one of butadiene-acrylonitrile copolymer, hydrogenated butadiene-acrylonitrile copolymer, ethylene-vinyl acetate copolymer, and acrylate homopolymer, and the mass percentage of the damping modifier in the blended material is ≤25%; The modified polyisoprene rubber layer has a first glass transition temperature and a second glass transition temperature, the first glass transition temperature is between -70°C and -50°C, the second glass transition temperature is between -40°C and -5°C, the ratio of F0 of the modified polyisoprene rubber layer at 23°C to F0 at -40°C is greater than or equal to 0.70 and less than 1, and the dissipation factor of the modified polyisoprene rubber layer in the range of -70°C to 10°C is ≥0.15.

[0035] Specifically, the diaphragm 20 is applied to a sound-generating device, which can be a large speaker or a micro speaker. The diaphragm 20 serves as a part of a vibration system. The diaphragm 20 is a folded ring diaphragm or a flat diaphragm. The diaphragm 20 includes a modified polyisoprene rubber layer. The diaphragm 20 is a single-layer structure or a multi-layer structure. The modified polyisoprene rubber layer is prepared using a blended material. The preparation method is, for example, compression molding, air pressure molding, etc. The blended material is mixed by a plurality of materials. For example, a plurality of materials are added to a mixer. Blending is carried out in the mixer and the mixture is evenly mixed to form a blended material.

[0036] Polyisoprene rubber is formed by the polymerization of isoprene. Rubber generally has a high loss factor only near the glass transition temperature. In the embodiment of the present invention, a damping modifier is added to enable the prepared modified polyisoprene rubber to have two different glass transition temperatures. Specifically, the glass transition temperature of the polyisoprene rubber is low, and the glass transition temperature of the damping modifier is high. The damping modifier is blended with the polyisoprene rubber and cross-linked in a mold to form a modified polyisoprene rubber layer. The modified polyisoprene rubber layer obtained after cross-linking has a first glass transition temperature and a second glass transition temperature, the first glass transition temperature is between -70°C and -50°C, and the second glass transition temperature is between -40°C and -5°C. That is to say, the modified polyisoprene rubber layer of the embodiment of the present invention has two glass transition temperature regions within the temperature range of -70°C to -5°C, so that the diaphragm 20 maintains a high loss factor within a wider temperature range. The loss factor of the diaphragm 20 within the range of -70°C to 10°C is ≥0.15, and it has a good damping effect within this temperature range, which can effectively reduce the THD of the sound-generating device using the diaphragm 20 and improve the listening yield of the sound-generating device. In addition, since the diaphragm 20 has two glass transition temperature regions between -70°C and -5°C, the elastic modulus of the diaphragm 20 changes smoothly within this temperature range, avoiding large fluctuations in F0 caused by drastic changes in the elastic modulus. The ratio of the F0 of the diaphragm 20 at 23°C to the F0 at -40°C is greater than or equal to 0.70 and less than 1, and the change of F0 with temperature is small.

[0037] It should be noted that if the weight percentage of the modified polyisoprene rubber layer in the blend is too low, blending of the blend will be difficult, and the elongation at break of the vulcanized material will be too low, which can easily cause film breakage during reliability testing. When the weight percentage of the polyisoprene rubber layer in the blend is ≥45%, blending of the blend is easy, and the resulting modified polyisoprene rubber has a high elongation at break.

[0038] Optionally, the mass percentage of the polyisoprene rubber in the blended material is 45%-70%. Within this range, the blended material is easily blended, the resulting modified polyisoprene rubber has a higher elongation at break, and the hardness of the material, which is too low due to an excessively high mass percentage of the polyisoprene rubber in the blended material, can be avoided.

[0039] In addition, the damping modifier includes any one or a mixture of butadiene-acrylonitrile copolymer, hydrogenated butadiene-acrylonitrile copolymer, ethylene-vinyl acetate copolymer, and acrylic acid ester homopolymer. These substances can chemically react with polyisoprene rubber to form a cross-linked structure, thereby forming a modified polyisoprene rubber layer with a dual glass transition temperature.

[0040] In addition, a ratio of the F0 of the diaphragm 20 at 23°C to the F0 at -40°C is greater than or equal to 0.70 and less than 1. The F0 of the diaphragm 20 at 23°C represents the resonant frequency of the diaphragm 20 at room temperature. The F0 of the diaphragm 20 at -40°C represents the resonant frequency of the diaphragm 20 at -40°C. The closer the ratio of the F0 of the diaphragm 20 at 23°C to the F0 at -40°C is to 1, the better the vibration stability of the diaphragm 20 at different temperatures.

[0041] Optionally, the ratio of F0 of the diaphragm 20 at 23° C. to F0 at −40° C. is 0.70, 0.75, 0.79, 0.82, 0.85, 0.87, 0.90, etc. Those skilled in the art may make the selection according to actual needs.

[0042] In an embodiment of the present invention, the diaphragm 20 includes a modified polyisoprene rubber layer, which is prepared from a blended material comprising polyisoprene rubber and a damping modifier. In an embodiment of the present invention, a damping modifier is added to the polyisoprene rubber so that the prepared modified polyisoprene rubber has two different glass transition temperatures. The polyisoprene rubber layer has a first glass transition temperature and a second glass transition temperature. The first glass transition temperature is between -70°C and -50°C, and the second glass transition temperature is between -40°C and -5°C. Therefore, the modified polyisoprene rubber of the embodiment of the present invention has two glass transition temperature regions within a temperature range of -70°C to -5°C, allowing the diaphragm 20 to maintain a high loss factor over a wide temperature range. The loss factor of the diaphragm 20 within the range of -70°C to 10°C is ≥0.15, which can effectively reduce the THD of a sound-generating device using the diaphragm 20 and improve the product's listening yield. Furthermore, because the diaphragm 20 has two glass transition temperature regions, the elastic modulus of the diaphragm 20 changes smoothly within this temperature range, avoiding large fluctuations in F0 caused by drastic changes in the elastic modulus. The ratio of the F0 of the diaphragm 20 at 23°C to the F0 at -40°C is greater than or equal to 0.70 and less than 1, demonstrating the vibration stability of the diaphragm 20 at different temperatures.

[0043] In some specific embodiments of the present invention, the glass transition temperature of the polyisoprene rubber is -70°C to -50°C; And / or, the glass transition temperature of the damping modifier is -40°C to -5°C.

[0044] In the embodiments of the present invention, the low-glass-transition-temperature isoprene and the high-glass-transition-temperature damping modifier can respectively improve the loss factor of the modified polyisoprene rubber in low- and high-temperature ranges. The glass transition temperature of polyisoprene rubber is typically in the range of -70°C to -50°C, resulting in the modified foreign diene rubber having a higher loss factor in a relatively low temperature range, such as -70°C to -50°C.

[0045] The glass transition temperature of the damping modifier is -40°C to -5°C, so that the modified foreign diene rubber has a higher loss factor in a relatively high temperature range, for example, -45°C to 10°C.

[0046] In some specific embodiments of the present invention, the polyisoprene rubber includes an isoprene polymer, and the molecular structure of the isoprene polymer is: , Wherein, a, b, and c are integers and cannot be 0 at the same time.

[0047] In this embodiment, the foreign diene polymer can be blended with the damping modifier and form a modified polyisoprene rubber.

[0048] In some specific embodiments of the present invention, the damping modifier includes a butadiene-acrylonitrile copolymer, and the molecular structure of the butadiene-acrylonitrile copolymer is: , Wherein, d and e are integers and cannot be 0 at the same time; f is a natural number; And / or, the damping modifier includes a hydrogenated butadiene-acrylonitrile copolymer, and the molecular structure of the hydrogenated butadiene-acrylonitrile copolymer is:

[0049] Wherein, g and h are integers and cannot be 0 at the same time; i is a natural number; j and k are integers and cannot be 0 at the same time; And / or, the damping modifier comprises ethylene-vinyl acetate copolymer, and the molecular structure of the ethylene-vinyl acetate copolymer is: , Among them, m and n are natural numbers; And / or, the damping modifier comprises an acrylate homopolymer, and the molecular structure of the acrylate homopolymer is: , Among them, r, s, and t are integers and cannot be 0 at the same time; R1, R2, and R3 are any one of methyl, ethyl, propyl, butyl, and 2-ethylhexyl.

[0050] In this embodiment, the above polymers can be blended with the isoprene polymer to form a modified polyisoprene rubber.

[0051] In some specific embodiments of the present invention, the blended material further includes a filler, and the filler includes at least one of silica, carbon black, mineral whiskers, talc, diatomaceous earth, calcium carbonate, kaolin, carbon nanotubes, graphene, clay, and mica, and the mass percentage of the filler in the blended material is 25%-50%.

[0052] In this embodiment, the filler is used to improve the mechanical properties of the diaphragm 20, such as tensile strength and hardness. When preparing the diaphragm 20, the filler can be one or a mixture of multiple materials selected from the group consisting of silicon dioxide, carbon black, mineral whiskers, talc, diatomaceous earth, calcium carbonate, kaolin, carbon nanotubes, graphene clay, and mica.

[0053] During compounding, the filler accounts for 25wt%-50wt% of the blended material.

[0054] It should be noted that the lower the filler content, the lower the tensile strength of the diaphragm 20, especially when the filler accounts for less than 25wt% by mass in the blended material, the reinforcement effect on the diaphragm 20 is poor. If the filler content is too high, for example, when the filler accounts for more than 50wt% by mass in the blended material, the elongation at break of the diaphragm 20 will drop significantly, and the toughness of the material will be insufficient, causing the diaphragm 20 to easily break during vibration. When the filler accounts for 25wt%-50wt% by mass in the blended material, the diaphragm 20 has sufficient tensile strength, elongation at break, and toughness.

[0055] Optionally, the mass proportion of the filler in the blended material is 25wt%, 30wt%, 40wt%, 50wt%, etc. Of course, the mass proportion of the filler in the blended material is not limited to the above embodiment, and those skilled in the art can make a selection according to actual needs.

[0056] In some specific embodiments of the present invention, the blended material further includes a vulcanizing agent, the vulcanizing agent includes sulfur, and the mass percentage of the sulfur in the blended material is 0.2%-2.5%.

[0057] In this embodiment, a vulcanizing agent is added to the blended material, and the vulcanizing agent is sulfur. The vulcanizing agent is used to cause a cross-linking reaction between the polyisoprene rubber and the damping modifier, thereby forming a network structure.

[0058] It should be noted that when mixing, the mass of sulfur accounts for 0.2wt%-2.5wt% of the total mass of the blended material. It should be noted that the less the mass content of sulfur, the insufficient degree of crosslinking of the blended material, and the poor stability of the network structure formed by the blended material. When the mass proportion of the sulfur in the blended material is less than 0.2wt%, the degree of crosslinking of the diaphragm 20 is insufficient, and the network structure stability is poor. If the mass content of sulfur is too high, the hardness of the diaphragm 20 is large, the toughness is poor, and the elongation at break is too low. In particular, when the mass content of the sulfur in the blended material is greater than 2.5wt%, the elongation at break of the diaphragm 20 is too low and the long-term high temperature resistance of the modified polyisoprene rubber decreases, and membrane breakage is prone to occur. When the mass content of sulfur in the blended material is 0.2wt%-2.5wt%, it can ensure that the diaphragm 20 has sufficient degree of crosslinking and can also make the diaphragm 20 have a higher elongation at break.

[0059] Optionally, the mass proportion of sulfur in the blended material is 0.2 wt%, 0.5 wt%, 1 wt%, 2 wt%, 2.5 wt%, etc. Further, the mass proportion of sulfur in the blended material is 1 wt%-2 wt%. Those skilled in the art can make the selection according to actual needs.

[0060] In some specific embodiments of the present invention, the blended material further includes a vulcanizing agent, which includes at least one of 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane, tert-butyl isopropyl benzene peroxide, 4,4-bis(tert-butylperoxy) valerate, 1,1-bis(tert-butylperoxy)-3,3,5-trimethylcyclohexane diisopropyl benzene peroxide, dibenzoyl peroxide, and tert-butyl perbenzoate; the mass percentage of the vulcanizing agent in the blended material is 0.4%-2.5%.

[0061] In this embodiment, a vulcanizing agent is added to the blended material, and the vulcanizing agent is a peroxide. The vulcanizing agent can be one of 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane, tert-butyl isopropyl benzene peroxide, 4,4-bis(tert-butylperoxy) valerate, 1,1-bis(tert-butylperoxy)-3,3,5-trimethylcyclohexane, dicumyl peroxide, dibenzoyl peroxide, and tert-butyl perbenzoate, or a mixture of multiple thereof.

[0062] When mixing, the mass of the vulcanizing agent accounts for 0.4wt%-2.5wt% of the total mass of the blended material. It should be noted that the less the mass content of the vulcanizing agent, the insufficient degree of crosslinking of the blended material, and the poor stability of the network structure formed by the blended material. When the mass proportion of the vulcanizing agent in the blended material is less than 0.4wt%, the insufficient degree of crosslinking of the diaphragm 20 and the poor stability of the network structure. If the mass content of the vulcanizing agent is too high, the hardness of the diaphragm 20 is large, the toughness is poor, and the elongation at break is too low. Especially when the mass content of the vulcanizing agent in the blended material is greater than 2.5wt%, the elongation at break of the diaphragm 20 is too low, and film breakage is prone to occur. When the mass content of the vulcanizing agent in the blended material is 0.4wt%-2.5wt%, it can ensure that the diaphragm 20 has sufficient degree of crosslinking and can also make the diaphragm 20 have a higher elongation at break.

[0063] In some specific embodiments of the present invention, the blended 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, sulfenic acid amine accelerator, thiuram accelerator, zinc oxide, and stearic acid, and the mass percentage of the accelerator in the blended material is 0.3%-4.5%.

[0064] In this embodiment, the accelerator can accelerate the vulcanization speed, shorten the vulcanization time, and lower the vulcanization temperature, thereby reducing the amount of vulcanizing agent used. The blend material can include a mixture of one or more of tetramethylthiuram disulfide, tetraethylthiuram disulfide, 2-mercaptobenzothiazole, dibenzothiazole disulfide, N-cyclohexyl-2-benzothiazolesulfenamide, N-tert-butyl-2-benzothiazolesulfenamide, a sulfenic acid amine accelerator, a thiuram accelerator, zinc oxide, and stearic acid as the accelerator.

[0065] When mixing, the mass percentage of the accelerator in the blend material is 0.3%-4.5%. It should be noted that when the addition amount of the accelerator in the blend material is less than 0.3%, the accelerator accelerates the vulcanization speed, shortens the vulcanization time, and reduces the effect of the vulcanization temperature. When the addition amount of the accelerator in the blend material is greater than 4.5%, the speed of the vulcanization reaction is too fast, which easily leads to an uneven network structure of the molecules inside the rubber, and the diaphragm 20 is prone to breakage. When the mass percentage of the accelerator in the blend material is 0.3%-4.5%, the vulcanization reaction speed of the blend material is moderate.

[0066] Optionally, the mass percentage of the accelerator in the blended material is 0.3%, 1%, 2%, 3%, 4%, 4.5%, etc., which can be set by those skilled in the art according to actual needs.

[0067] In some specific embodiments of the present invention, the blended material further includes an antioxidant, which includes at least one of N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine, N,N'-diaryl-p-phenylenediamine, 2,6-di-tert-butyl-p-cresol, 2,2'-methylenebis(4-methyl-6-tert-butylphenol), 2,2,4-trimethyl-1,2-dihydroquinoline, and 6-ethoxy-2,2,4-trimethyl-1,2-dihydroquinoline; the mass percentage of the antioxidant in the blended material is 0.3%-3.5%.

[0068] During the use of polymer materials, as temperature rises and time increases, molecular chains break and autocatalytically active free radicals are generated. These autocatalytically active free radicals can accelerate the aging of the polymer material itself. Adding an antioxidant to the diaphragm 20 can halt the generation of autocatalytically active free radicals in the blended material, thereby delaying the aging of the blended material and extending the service life of the diaphragm 20. When preparing the diaphragm 20, one or more of a mixture of 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, and 6-ethoxy-2,2,4-trimethyl-1,2-dihydroquinoline can be selected as the antioxidant. The above-mentioned antioxidants are mutually soluble in the polyisoprene rubber and the damping modifier rubber, thereby preventing the diaphragm 20 from aging and extending the service life of the diaphragm 20.

[0069] When batching, the weight ratio of the antioxidant in the blend material is 0.3wt%-3.5wt%. It should be noted that in the blend material, the antioxidant addition is too little, for example, when the weight ratio of the antioxidant in the blend material is less than 0.3wt%, it is impossible to prevent the diaphragm 20 from aging and extend the service life of the diaphragm 20. The antioxidant addition is too much, for example, when the weight ratio of the antioxidant in the blend material is greater than 3.5wt%, the antioxidant cannot be better soluble in each other with polyisoprene rubber and damping modifier, so that the antioxidant cannot be evenly dispersed in the blend material, resulting in a decrease in the mechanical properties of the diaphragm 20. And when the weight ratio of the antioxidant in the blend material is 0.3wt%-3.5wt%, the antioxidant can effectively extend the service life of the diaphragm 20, and the antioxidant can be evenly dispersed in the blend material, and the diaphragm 20 prepared can maintain good mechanical properties.

[0070] Alternatively, the mass proportion of the antioxidant in the blend material is 0.3wt%, 0.5wt%, 1wt%, 2wt%, 3.5wt% etc. Further, the mass proportion of the antioxidant in the blend material is 2wt%-3wt%. Of course, the mass proportion of the antioxidant in the blend material is not limited to the above embodiment, and those skilled in the art can select according to actual needs.

[0071] In some specific embodiments of the present invention, the tensile strength of the modified polyisoprene rubber layer is ≥12 MPa.

[0072] In this embodiment, the tensile strength can reflect the reliability of the diaphragm 20. When the tensile strength of the modified polyisoprene rubber is less than 12 MPa, the reliability of the diaphragm 20 is likely to deteriorate, and the diaphragm 20 is prone to rupture after high-temperature and high-humidity testing and aging testing. When the tensile strength of the modified polyisoprene rubber is ≥12 MPa, the reliability of the diaphragm 20 is good, and the diaphragm 20 is unlikely to rupture after high-temperature and high-humidity testing and aging testing.

[0073] In some specific embodiments of the present invention, the diaphragm 20 is formed into a single-layer structure, and the diaphragm 20 is composed of a layer of the modified polyisoprene rubber; Alternatively, the diaphragm 20 is formed into a multi-layer structure, and the diaphragm 20 includes at least one layer of the modified polyisoprene rubber layer and a composite layer, the composite layer and the modified polyisoprene rubber layer are stacked, 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 invention can be a modified polyisoprene rubber layer with a single-layer structure. The diaphragm 20 has a simple structure and a simple manufacturing process.

[0075] Alternatively, the diaphragm 20 may have a multi-layer structure. Specifically, at least one modified polyisoprene rubber layer is laminated with a composite layer to form the multi-layer diaphragm 20. The composite layer is at least one of an elastomer layer, an engineering plastic layer, and a film layer. The multi-layer structure may have 2, 3, 4, 5, 6, 7, or other layers.

[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 PC, PBT, PI, PEEK, PAR, PMI, PET, PEN, PA, PEI, and LCP. The film layer is a silicone film and / or an acrylic film. The composite layer may be one or more layers.

[0077] According to another embodiment of the present invention, a sound generating device is provided. Figure 2-Figure 4 As shown, the sound-generating device 100 includes the diaphragm 20 of the above embodiment.

[0078] like Figure 2-Figure 3 As shown, the sound-generating device 100 is a micro-speaker. The sound-generating device 100 may include a housing 10, a magnetic circuit system, and a vibration system. The magnetic circuit system includes a permanent magnet 40, which is used to form 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 to the housing 10. The permanent magnet 40 is disposed on one side of the diaphragm 20 along the thickness direction. One end of the voice coil 30 is connected to the diaphragm 20, and the other end is located in the magnetic gap.

[0079] In this example, the diaphragm 20 may be a surround diaphragm. The surround diaphragm comprises a central portion, a surround portion, and a fixed portion, connected in sequence from the inside out. The fixed portion is used to connect to the housing 10. A dome is provided on the central portion, and the voice coil 30 is connected to the central portion or the dome.

[0080] In other examples, the diaphragm 20 may also be a planar diaphragm or other structures. Those skilled in the art may determine this according to actual conditions, and no specific limitation is made here.

[0081] Figure 4 Another sound-generating device 100 according to an embodiment of the present invention is shown. The sound-generating device is a large loudspeaker.

[0082] The sound-generating device 100 may include a shell 10, a magnetic circuit system and a vibration system. The magnetic circuit system includes a permanent magnet 40 and a U iron 90. The permanent magnet 40 and the U iron 90 are used to form a magnetic gap. The vibration system includes 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 arranged 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 to 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 part of the skeleton 80.

[0083] In this example, the diaphragm 20 may be a surround diaphragm. The surround diaphragm includes a central portion, a surround portion, and a fixed portion connected from the inside out. The fixed portion is used to connect to the housing 10. The central portion is connected to the outer edge of the cone 50.

[0084] In other examples, the diaphragm 20 may also be a planar diaphragm or other structures. Those skilled in the art may determine this according to actual conditions, and no specific limitation is made here.

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

[0086] The electronic device is, for example, a mobile phone, a computer, a television, a speaker, an intercom, a VR device, an AR device, smart glasses, etc. The electronic device includes the sound-generating device 100 described in the above embodiment. Of course, the electronic device of the present invention also includes at least all the beneficial effects of the above embodiment, which will not be described in detail here.

[0087] The diaphragm 20 and the sound generating device 100 of the present invention are described in detail below with reference to specific embodiments. It should be noted that the following description is merely exemplary and does not specifically limit the present invention.

[0088] Example: Diaphragm 20 is a single-layer, ring-shaped diaphragm. Diaphragm 20 has a thickness of 120 μm. It consists of a layer of modified polyisoprene rubber, formed by compression molding. The modified polyisoprene rubber layer is made from a blend of polyisoprene rubber and a damping modifier. The damping modifier is a butadiene-acrylonitrile copolymer. The specific ingredients of the blend are shown in Table 1.

[0089] Comparative Example: The diaphragm 20 is a single-layer surround diaphragm. The thickness of the diaphragm 20 is 110 μm. It is composed of a single layer of polyisoprene rubber and is formed by compression molding. The specific ingredients of the blended material are shown in Table 1.

[0090] Table 1 - Ingredients of Example and Comparative Example Diaphragm 20

[0091] Performance testing: (1) The hardness (Shore A), tensile strength, tear strength, dissipation factor (-60°C to 10°C, taking the minimum value), and glass transition temperature of the diaphragm 20 of the embodiment and the comparative example were tested respectively. It should be noted that, considering the difference between the size of the diaphragm 20 and the sample size required by the corresponding test standard, a sample composed of the same material as the diaphragm 20 was selected for the relevant tests to characterize the characteristics of the diaphragm 20. Since the sample and the diaphragm 20 were composed of the same material, the relevant characteristics of the sample measured were consistent with the relevant characteristics of the diaphragm 20.

[0092] Among them, hardness (Shore A), tensile strength and tear strength are tested according to ASTM-D882 standard, and the test temperature is 23℃.

[0093] Dissipation factor, also known as damping factor, is the ratio of loss modulus to storage modulus. It is measured using a dynamic thermomechanical analyzer according to ASTM D5026-23. The frequency is 1 Hz and the strain is 0.2%.

[0094] The glass transition temperature was tested using a dynamic thermomechanical analyzer according to ASTM D5026-23, with a frequency of 1 Hz and a strain of 0.2%.

[0095] (2) Assemble the diaphragms 20 of the embodiment and the comparative example into the sound-generating device. The two diaphragms 20 have the same size. Test the THD curves of the two sound-generating devices. Figure 4 .

[0096] (3) Reliability test: The diaphragms 20 of the embodiment and comparative example were assembled into a sound-generating device. The sound-generating device was a large speaker. After the sound-generating device was operated for 168 hours at 65°C and 95% humidity, the acoustic performance was tested and the listening yield was calculated. Calculation method: The HOHD curves of 10 speakers were tested and compared with the standard frame line. Products that exceeded the frame line were judged as NG. The diaphragms 20 of the embodiment and the comparative example were assembled into a sound-generating device, and the F0 of the sound-generating device was tested at 23° C. and −40° C., respectively. The ratio of the F0 at 23° C. and −40° C. was calculated.

[0097] Results and Analysis: (1) The test results of the hardness (Shore A), tensile strength, tear strength, loss factor (-60°C to 10°C, taking the minimum value), and glass transition temperature of the diaphragm 20 of the embodiment and the comparative example are shown in Table 2.

[0098] Table 2 - Performance test of embodiment and comparative example diaphragm 20

[0099] As can be seen from Table 2, the hardness of the diaphragm 20 of the embodiment of the present invention is the same as that of the diaphragm 20 of the comparative example, but the tensile strength, tear strength, and loss factor of the diaphragm 20 of the embodiment of the present invention are all higher than those of the diaphragm 20 of the comparative example. This is mainly because the main components of the raw materials of the diaphragm 20 of the embodiment of the present invention and the diaphragm 20 of the comparative example are polyisoprene rubber and the proportion of the added filler carbon black is basically the same, so the hardness of the diaphragm 20 of the embodiment is the same as that of the diaphragm 20 of the comparative example. However, since the modified polyisoprene rubber of the diaphragm 20 of the embodiment of the present invention has two glass transition temperatures (i.e., -61°C and -19°C), the diaphragm 20 maintains a high loss factor in the temperature range of -70°C to 10°C. The diaphragm 20 of Comparative Example 1 is made of polyisoprene rubber and has only one glass transition temperature, and cannot maintain a high loss factor in a wider temperature range. In addition, the damping modifier is a butadiene-acrylonitrile copolymer, i.e., nitrile rubber. The acrylonitrile group in the nitrile rubber has high polarity, which can enhance the intermolecular force of the material and improve the tensile strength and tear strength of the diaphragm 20.

[0100] (2) By Figure 4It can be seen that in the range of 100Hz-1000Hz, the THD curve of the sound-emitting device of the embodiment of the present invention is generally lower than the THD curve of the sound-emitting device of the comparative example. In the range above 1000Hz, the difference between the THD curve of the sound-emitting device of the embodiment of the present invention and the THD curve of the sound-emitting device of the comparative example is relatively small. This is because the vibration mold of the embodiment of the present invention is prepared by blending a damping modifier with polyisoprene rubber. The modified polyisoprene rubber layer obtained after cross-linking has a first glass transition temperature and a second glass transition temperature, the first glass transition temperature is -61°C, and the second glass transition temperature is -19°C. In other words, the modified polyisoprene rubber of the embodiment of the present invention has two glass transition temperature regions, so that the diaphragm 20 maintains a high loss factor in a wider temperature range, which can effectively reduce the THD of the sound-emitting device using the diaphragm 20.

[0101] (3) After testing, the sound yield rate of the sound-generating device of the embodiment of the present invention reached 100%. The sound yield rate of the sound-generating device of the comparative example was 51%. The sound yield rate of the sound-generating device of the embodiment of the present invention was significantly higher than that of the sound-generating device of the comparative example.

[0102] The F0 at 23°C / F0 at -40°C of the sound-generating device of the embodiment of the present invention is 0.75, which is much higher than the F0 at 23°C / F0 at -40°C of the sound-generating device of the comparative example, which is 0.60. At 23°C, the F0 of the embodiment is 110 Hz, and at -40°C, the F0 is 147 Hz; at 23°C, the F0 of the comparative example is 112 Hz, and at -40°C, the F0 is 187 Hz. This demonstrates the excellent long-term reliability of the sound-generating device of the embodiment of the present invention. This is primarily due to the fact that the diaphragm of the embodiment of the present invention is prepared by blending a damping modifier with polyisoprene rubber. The modified polyisoprene rubber layer obtained after cross-linking has a first glass transition temperature of -61°C and a second glass transition temperature of -19°C. In other words, the modified polyisoprene rubber of the embodiment of the present invention has two glass transition temperature regions within a wide temperature range, resulting in a smoother modulus change and higher damping of the diaphragm of the sound-generating device of the embodiment.

[0103] In summary, the modified polyisoprene rubber of the diaphragm 20 of the embodiment of the present invention has two glass transition temperatures (i.e., -61°C and -19°C), and the diaphragm 20 maintains a high loss factor within the temperature range of -70°C to 10°C. The vibration mold of the embodiment of the present invention is prepared by blending a damping modifier with polyisoprene rubber. The modified polyisoprene rubber layer obtained after cross-linking has a first glass transition temperature and a second glass transition temperature, the first glass transition temperature is -61°C, and the second glass transition temperature is -19°C. In other words, the modified polyisoprene rubber of the embodiment of the present invention has two glass transition temperature regions within a wider temperature range, so that the diaphragm 20 maintains a high loss factor within a wider temperature range, can effectively reduce the THD of the sound-generating device using the diaphragm 20, has a higher listening yield, and makes the modulus change of the diaphragm 20 more gentle and the damping higher within this temperature range.

[0104] The above embodiments focus on the differences between the various embodiments. As long as the different optimization features between the various embodiments are not contradictory, they can be combined to form a better embodiment. Considering the simplicity of the text, they will not be repeated here.

[0105] Although some specific embodiments of the present invention have been described in detail by way of examples, it should be understood by those skilled in the art that the above examples are for illustration only and are not intended to limit the scope of the present invention. It should be understood by those skilled in the art that modifications may be made to the above embodiments without departing from the scope and spirit of the present invention. The scope of the present invention is defined by the appended claims.

Claims

1. A diaphragm for a sound-generating device, characterized in that: The diaphragm includes a modified polyisoprene rubber layer, which is prepared from a blended material including polyisoprene rubber and a damping modifier; the mass percentage of the polyisoprene rubber in the blended material is ≥45%; The damping modifier includes at least one of butadiene-acrylonitrile copolymer, hydrogenated butadiene-acrylonitrile copolymer, ethylene-vinyl acetate copolymer, and acrylate homopolymer, and the mass percentage of the damping modifier in the blended material is ≤25%; The modified polyisoprene rubber layer has a first glass transition temperature and a second glass transition temperature, the first glass transition temperature is between -70°C and -50°C, the second glass transition temperature is between -40°C and -5°C, the ratio of F0 of the modified polyisoprene rubber layer at 23°C to F0 at -40°C is greater than or equal to 0.70 and less than 1, and the dissipation factor of the modified polyisoprene rubber layer in the range of -70°C to 10°C is ≥0.

15.

2. The diaphragm according to claim 1, wherein The glass transition temperature of the polyisoprene rubber is -70°C to -50°C; And / or, the glass transition temperature of the damping modifier is -40°C to -5°C.

3. The diaphragm according to claim 1, wherein The polyisoprene rubber includes isoprene homopolymer, and the molecular structure of the isoprene homopolymer is: ， Wherein, a, b, and c are integers and cannot be 0 at the same time.

4. The diaphragm according to claim 1, wherein The damping modifier includes a butadiene-acrylonitrile copolymer, and the molecular structure of the butadiene-acrylonitrile copolymer is: ， Wherein, d and e are integers and cannot be 0 at the same time; f is a natural number; And / or, the damping modifier includes a hydrogenated butadiene-acrylonitrile copolymer, and the molecular structure of the hydrogenated butadiene-acrylonitrile copolymer is: Wherein, g and h are integers and cannot be 0 at the same time; i is a natural number; j and k are integers and cannot be 0 at the same time; And / or, the damping modifier comprises ethylene-vinyl acetate copolymer, and the molecular structure of the ethylene-vinyl acetate copolymer is: ， Among them, m and n are natural numbers; And / or, the damping modifier comprises an acrylate homopolymer, and the molecular structure of the acrylate homopolymer is: ， Among them, r, s, and t are integers and cannot be 0 at the same time; R1, R2, and R3 are any one of methyl, ethyl, propyl, butyl, and 2-ethylhexyl.

5. The diaphragm according to claim 1, wherein: The blended material also includes a filler, which includes at least one of silicon dioxide, carbon black, mineral whiskers, talc, diatomaceous earth, calcium carbonate, kaolin, carbon nanotubes, graphene, clay, and mica. The mass percentage of the filler in the blended material is 25%-50%.

6. The diaphragm according to claim 1, wherein: The blended material further includes a vulcanizing agent, which includes sulfur. The mass percentage of the sulfur in the blended material is 0.2%-2.5%.

7. The diaphragm according to claim 1, wherein: The blended material also includes a vulcanizing agent, which includes: at least one of 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane, tert-butyl isopropyl benzene peroxide, 4,4-bis(tert-butylperoxy) butyl valerate, 1,1-bis(tert-butylperoxy)-3,3,5-trimethylcyclohexane, diisopropyl benzene peroxide, dibenzoyl peroxide, and tert-butyl perbenzoate; the mass percentage of the vulcanizing agent in the blended material is 0.4%-2.5%.

8. The diaphragm according to claim 1, wherein: The blended material also 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, sulfenic acid amine accelerator, thiuram accelerator, zinc oxide, and stearic acid. The mass percentage of the accelerator in the blended material is 0.3%-4.5%.

9. The diaphragm according to claim 1, wherein: The blended material also includes an antioxidant, which includes at least one of N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine, N,N'-diaryl-p-phenylenediamine, 2,6-di-tert-butyl-p-cresol, 2,2'-methylenebis(4-methyl-6-tert-butylphenol), 2,2,4-trimethyl-1,2-dihydroquinoline, and 6-ethoxy-2,2,4-trimethyl-1,2-dihydroquinoline; the mass percentage of the antioxidant in the blended material is 0.3%-3.5%.

10. The diaphragm according to claim 1, wherein: The tensile strength of the modified polyisoprene rubber layer is ≥12 MPa.

11. The diaphragm according to any one of claims 1 to 10, characterized in that: The diaphragm is formed into a single-layer structure, and the diaphragm is composed of a layer of the modified polyisoprene rubber; Alternatively, the diaphragm is formed into a composite layer structure, the diaphragm includes at least one layer of the modified polyisoprene rubber layer and a composite layer, the composite layer and the modified polyisoprene rubber layer are stacked, and the composite layer is at least one of an elastomer layer, an engineering plastic layer and a film layer.

12. The diaphragm according to any one of claims 1 to 10, characterized in that: The mass percentage of the polyisoprene rubber in the blended material is 45%-70%.

13. A sound-generating device, characterized in that: Comprising a diaphragm as described in any one of claims 1-12.

14. An electronic device, characterized in that: Comprising the sound-generating device as claimed in claim 13.

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