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 is of a single-layer structure and is prepared from a blending material, the blending material comprises ethylene-acrylate rubber and acrylate rubber, the ethylene-acrylate rubber is of a ternary structure, the molecular formula of the ethylene-acrylate rubber is # imgabs0 #, and x, y and z are natural numbers; r and R'are alkyl groups; the molecular formula of the acrylate rubber contains carboxylic acid groups and / or epoxy groups; in the blended material, the ratio of the mass of the acrylate rubber to the total mass of the acrylate rubber and the ethylene-acrylate rubber is 10%-50%; after the vibrating diaphragm is aged for 168 hours at the temperature of 150 DEG C, the elongation at break retention rate is greater than or equal to 52%, and the room temperature damping factor of the vibrating diaphragm is greater than or equal to 0.3. According to the vibrating diaphragm, due to hydrogen bonds formed by ester groups and microscopic phase separation of materials, the damping performance of the vibrating diaphragm is improved. Under a large amplitude, polarization and distortion of the vibrating diaphragm are small, and heat resistance is good.

Description

Technical Field

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

[0002] In the related art, the diaphragm of high-performance micro speakers is usually made of AEM rubber material. As consumers' demands for the sound quality and volume of speakers of electronic devices become higher and higher, the amplitude of the speaker diaphragm becomes larger and larger. The increase in amplitude makes the polarization and distortion of the speaker higher and higher during vibration, which puts higher requirements on the damping performance of the diaphragm. However, the room temperature damping factor of the diaphragm made of AEM rubber material is low, the distortion is large, and the heat resistance is poor, which makes it difficult to meet the use requirements of the speaker. 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 is formed into a single-layer structure, and the diaphragm is prepared from a blended material, and the blended material includes ethylene-acrylate rubber and acrylate rubber, wherein the ethylene-acrylate rubber is a ternary structure, and its molecular formula is: , Wherein, x, y, z are natural numbers; R and R' are alkyl groups; The molecular formula of the acrylic rubber contains carboxylic acid groups and / or epoxy groups; In the blended material, the ratio of the mass of the acrylic rubber to the total mass of the acrylic rubber and the ethylene-acrylate rubber is 10%-50%; the retention rate of the elongation at break of the diaphragm after aging for 168 hours at 150°C is greater than or equal to 52%, and the room temperature damping factor of the diaphragm is greater than or equal to 0.3.

[0005] Optionally, the elongation at break of the diaphragm at room temperature is greater than or equal to 110%; And / or, the stress loss rate of the diaphragm is greater than or equal to 30%.

[0006] Optionally, the blended material further includes an amine cross-linking agent, and the amine cross-linking agent includes at least one of hexamethylenediamine, hexamethylenediamine salt, hexamethylenediamine carbamate, triethylenetetramine, 2,2'-methylenedianiline and di-o-tolylguanidine. Optionally, the mass proportion of the amine cross-linking agent in the blended material is 0.2%-5wt%.

[0007] Optionally, the diaphragm hardness is 45A-80A; And / or, the glass transition point of the diaphragm is -60°C-10°C.

[0008] Optionally, the ratio of the mass of the acrylic rubber to the total mass of the acrylic rubber and the ethylene-acrylate rubber is 20%-40%.

[0009] Optionally, the blended material further includes a reinforcing agent, which is at least one of white carbon black, talcum powder, carbon black, and calcium carbonate, and the mass proportion of the reinforcing agent in the blended material is 5wt%-60wt%.

[0010] Optionally, the blended material also includes an antioxidant, which includes at least one of antioxidant N-445, antioxidant 246, antioxidant 4010, antioxidant SP, antioxidant RD, antioxidant ODA, antioxidant OD, and antioxidant WH-02, and the mass proportion of the antioxidant in the blended material is 0.2wt%-6wt%.

[0011] Optionally, the room temperature storage modulus of the diaphragm is 2MPa-50Mpa; And / or, the density of the diaphragm is 1.1 g / cm 3 -1.65g / cm 3 ; And / or, the thickness of the diaphragm is 20 μm-150 μm.

[0012] According to a second aspect of the present invention, a sound-generating device is provided, which includes the diaphragm described in the present invention.

[0013] According to a third aspect of the present invention, an electronic device is provided, which includes the sound generating device of the present invention.

[0014] The diaphragm of the embodiment of the present invention is prepared by a blended material including ethylene-acrylate rubber and acrylate rubber. The hydrogen bonds formed by the ester groups in the diaphragm and the microscopic phase separation of the material improve the damping performance of the diaphragm. When the ratio of the mass of the acrylate rubber to the total mass of the acrylate rubber and the ethylene-acrylate rubber is 10%-50%, the diaphragm has both high damping performance and toughness. In addition, the polarity of acrylic rubber is large and the intermolecular force is large. When the ratio of the mass of the acrylate rubber to the total mass of the acrylate rubber and the ethylene-acrylate rubber is 10%-50%, the retention rate of the elongation at break of the diaphragm after aging for 168 hours at 150°C is greater than or equal to 52%, so that the diaphragm has high temperature resistance and high stability under long-term use, meeting its use requirements under extreme working conditions. In addition, the room temperature damping factor of the diaphragm is greater than or equal to 0.3, and the hardness is moderate, which makes the diaphragm significantly reduce polarization and distortion under large amplitudes, and it is not easy to break the membrane. The diaphragm of the present invention is a single-layer structure with good mechanical properties, can meet the use requirements without being compounded with other material layers, has a simple structural design and low production cost.

[0015] The ternary structure of ethylene-acrylate and acrylate containing carboxylic acid group and / or epoxy group can react with the crosslinking agent in the air, and the diaphragm can be formed by air pressure molding, which makes the preparation process of the diaphragm simple and saves production costs.

[0016] 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 attached drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention.

[0018] Figure 1 is a cross-sectional view of a diaphragm according to an embodiment of the present invention.

[0019] Figure 2 is a stereoscopic diagram of a sound-generating device according to an embodiment of the present invention.

[0020] Figure 3 is a cross-sectional view of a sound generating device according to an embodiment of the present invention.

[0021] Figure 4 3 is a total harmonic distortion curve of the micro-speaker according to the embodiment of the present invention and the micro-speaker according to comparative example 1.

[0022] Reference numerals: 100. Sound-generating device; 10. Shell; 20. Diaphragm; 30. Voice coil; 40. Permanent magnet. DETAILED DESCRIPTION

[0023] Various exemplary embodiments of the present invention 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 do not limit the scope of the present invention unless otherwise specifically stated.

[0024] 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.

[0025] 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 as part of the specification.

[0026] 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.

[0027] It should be noted that like reference numerals and letters refer to similar items in the following figures, and therefore, once an item is defined in one figure, it need not be further discussed in subsequent figures.

[0028] The diaphragm 20 according to the embodiment of the present invention is described in detail below with reference to the accompanying drawings.

[0029] According to a specific embodiment of the present invention, a diaphragm 20 for a sound-generating device is provided. Figure 1 As shown, the diaphragm 20 is formed into a single-layer structure, and the diaphragm 20 is prepared from a blended material, wherein the blended material includes ethylene-acrylate rubber (ie, AEM rubber) and acrylate rubber (ie, ACM rubber), wherein the ethylene-acrylate rubber is a ternary structure, and its molecular formula is: , Wherein, x, y, z are natural numbers; R and R' are alkyl groups; optionally, R' is methyl, ethyl or butyl. AEM rubber containing the above groups is widely available, and the preparation process of the diaphragm 20 is simple.

[0030] The molecular formula of the acrylic rubber contains carboxylic acid groups and / or epoxy groups; In the blended material, the ratio of the mass of the acrylic rubber to the total mass of the acrylic rubber and the ethylene-acrylate rubber is 10%-50%; the retention rate of the elongation at break of the diaphragm after aging for 168 hours at 150°C is greater than or equal to 52%, and the room temperature damping factor of the diaphragm is greater than or equal to 0.3.

[0031] In other words, the diaphragm 20 is applied to a sound-generating device. The diaphragm 20 is a part of a vibration system. The diaphragm 20 is a folded ring diaphragm or a flat diaphragm. The diaphragm 20 is a single-layer structure and does not need to be compounded with other membrane layers. This makes the preparation process of the diaphragm 20 simple. The diaphragm 20 is made of a blended material. The preparation method is, for example, compression molding, air pressure molding, etc. The blended material is mixed with a variety of materials. For example, a variety of materials are added to a mixer. Blending is performed in a mixer and mixed evenly to form a blended material. In this embodiment, the blended material includes AEM rubber and ACM rubber. Among them, AEM rubber is an elastomer obtained by copolymerization with ethylene-acrylate as the main monomer. ACM rubber is an elastomer obtained by copolymerization with acrylate as the main monomer.

[0032] During the preparation, AEM rubber and ACM rubber are added to a mixer for mixing to form a blended material. The formed blended material is formed into a single-layer diaphragm 20 by compression molding or air pressure molding. During the molding, the blended material undergoes a cross-linking reaction to perform vulcanization. Of course, the method for preparing the diaphragm 20 is not limited to the above embodiment, and those skilled in the art can select according to actual needs.

[0033] Among them, ethylene-acrylate rubber is a ternary structure, and its molecular formula is: .

[0034] It should be noted that when the diaphragm 20 is prepared by air pressure molding, the blended material is vulcanized in the air. Compared with the AEM rubber with a binary structure, the diaphragm 20 cannot be prepared by air pressure molding. The AEM rubber of the present invention has a ternary structure, which is simpler to manufacture and saves costs.

[0035] The molecular formula of acrylate rubber contains carboxylic acid groups and / or epoxy groups, that is, the molecular formula of acrylate rubber may contain only carboxylic acid groups, the molecular formula of acrylate rubber may contain only epoxy groups, or the molecular formula of acrylate rubber may contain both carboxylic acid groups and epoxy groups. The above two groups act as crosslinking points and react with the crosslinking agent during the crosslinking process, thereby vulcanizing the blended material.

[0036] In the embodiment of the present invention, since the ester content in ACM rubber is much higher than that in AEM rubber, there is a certain microscopic phase separation in the material, so the damping property of the diaphragm 20 during movement is significantly increased. Therefore, as the ACM rubber content increases, the ester content in the blended material increases significantly, the hydrogen bond content between the molecular chains increases, the friction force increases during the movement of the molecular chains, the internal friction increases, and the damping performance of the diaphragm 20 increases significantly. However, due to the poor molecular flexibility of ACM rubber, when there are too many hydrogen bonds, the toughness of the diaphragm 20 will decrease. When the ratio of the mass of the acrylic rubber to the total mass of the acrylic rubber and the ethylene-acrylic rubber is 10%-50%, the diaphragm 20 has both high damping performance and toughness. The single-layer diaphragm in the present invention has good mechanical properties and can meet the use requirements without being compounded with other material layers. The structural design is simple, the production is convenient, and the cost is saved.

[0037] Optionally, in the blended material, the ratio of the mass of the acrylic rubber to the total mass of the acrylic rubber and the ethylene-acrylic rubber is 10%, 20%, 30%, 40%, 50%. Further, in the blended material, the ratio of the mass of the acrylic rubber to the total mass of the acrylic rubber and the ethylene-acrylic rubber is 20%-40%. Of course, the ratio of the mass of the acrylic rubber to the total mass of the acrylic rubber and the ethylene-acrylic rubber is not limited to the above embodiments, and those skilled in the art can make a selection according to actual needs.

[0038] In addition, the ratio of the mass of the acrylic rubber to the total mass of the acrylic rubber and the ethylene-acrylate rubber is 10%-50%, so that the retention rate of the elongation at break of the diaphragm after aging for 168 hours at 150°C is greater than or equal to 52%, and the room temperature damping factor of the diaphragm is greater than or equal to 0.3.

[0039] The elongation at break retention rate refers to the degree of retention of the elongation at break of a material after aging relative to the initial elongation at break. Before the test, the diaphragm 20 was aged for 168 hours at a temperature of 150°C. The elongation at break of the diaphragm 20 can be tested in accordance with the ASTM D412-2016 standard. It should be noted that the higher the elongation at break retention rate, the higher the temperature resistance and stability of the material; conversely, the lower the temperature resistance and stability of the material. The diaphragm 20 of the embodiment of the present invention, because the ACM rubber of the blended material contains a large number of ester groups, a large number of hydrogen bonds are formed between molecules. A large number of hydrogen bonds make the intermolecular force large, so the elongation at break retention rate of the diaphragm 20 is significantly improved. The elongation at break retention rate of the diaphragm 20 after aging for 168 hours at a temperature of 150°C is greater than or equal to 52%, so that the diaphragm 20 has high temperature resistance and high stability under long-term use, which meets its use requirements under extreme working conditions.

[0040] Due to the hydrogen bonds formed by the ester groups in the diaphragm 20 and the microscopic phase separation of the material, the damping performance of the diaphragm 20 is improved, for example, the room temperature damping factor is greater than or equal to 0.3. Compared with the diaphragm made of pure AEM rubber, under the same hardness conditions, the room temperature damping factor of the diaphragm 20 of the embodiment of the present invention is significantly improved. The room temperature damping factor of the diaphragm 20 of the embodiment of the present invention is greater than or equal to 0.3, and the hardness is moderate, which makes the diaphragm 20 significantly reduce polarization and distortion at a larger amplitude, and is not prone to membrane rupture.

[0041] Optionally, the elongation at break retention rate of the diaphragm 20 is 52%, 53%, 55%, 58%, 60%, 65%, etc. The room temperature damping factor is 0.3, 0.34, 0.4, 0.45, etc. Of course, the elongation at break retention rate and the room temperature damping factor of the diaphragm 20 are not limited to the above embodiments, and those skilled in the art can select according to actual needs.

[0042] In addition, the ternary structure of ethylene-acrylate and acrylate containing carboxylic acid groups and / or epoxy groups can react with a crosslinking agent in the air and form the diaphragm 20 by air pressure molding. This simplifies the preparation process of the diaphragm 20 and saves production costs.

[0043] The diaphragm 20 of the embodiment of the present invention is made of a blended material including ethylene-acrylate rubber and acrylate rubber. The hydrogen bonds formed by the ester groups in the diaphragm 20 and the microscopic phase separation of the material improve the damping performance of the diaphragm 20. When the ratio of the mass of the acrylate rubber to the total mass of the acrylate rubber and the ethylene-acrylate rubber is 10%-50%, the diaphragm 20 has both high damping performance and toughness. In addition, the polarity of acrylic rubber is large and the intermolecular force is large. When the ratio of the mass of the acrylate rubber to the total mass of the acrylate rubber and the ethylene-acrylate rubber is 10%-50%, the elongation at break retention rate of the diaphragm 20 after aging for 168 hours at 150°C is greater than or equal to 52%, so that the diaphragm 20 has high temperature resistance and high stability under long-term use, meeting its use requirements under extreme working conditions. The room temperature damping factor of the diaphragm 20 is greater than or equal to 0.3, and the hardness is moderate, which significantly reduces the polarization and distortion of the diaphragm 20 at a larger amplitude, and is less likely to cause film breakage. The diaphragm of the present invention is a single-layer structure with good mechanical properties, can meet the use requirements without being compounded with other material layers, has a simple structural design and low production cost.

[0044] The ternary structure of ethylene-acrylate and acrylate containing carboxylic acid group and / or epoxy group can react with the crosslinking agent in the air, and can be formed into the diaphragm 20 by air pressure molding. This simplifies the preparation process of the diaphragm 20 and saves production costs.

[0045] In a specific embodiment of the present invention, the elongation at break of the diaphragm at room temperature is greater than or equal to 110%; And / or, the stress loss rate of the diaphragm is greater than or equal to 30%.

[0046] In an embodiment of the present invention, the diaphragm 20 satisfies at least one of the above conditions or satisfies both of the above conditions at the same time. The elongation at break of the diaphragm 20 is tested at room temperature, for example, it can be tested according to the ASTM D412-2016 standard. The elongation at break refers to the percentage of the length of the material when it breaks after stretching to the length before stretching. The lower the elongation at break of a material, the worse the toughness of the material, and the more likely it is that the membrane will break. The diaphragm 20 of the embodiment of the present invention has a high polarity and a strong intermolecular force of ACM rubber, so that the elongation at break of the diaphragm 20 is greater than or equal to 110%. The diaphragm 20 has good toughness and is not prone to membrane breakage.

[0047] The stress loss rate refers to the ratio of the stress reduction of a material due to factors such as time, environment, and temperature during the stress process. The stress loss rate of the diaphragm 20 can be tested according to the ASTM D5026-15 standard. It should be noted that the higher the stress loss rate, the more complete the stress release of the diaphragm 20 during the molding process, and the lower the dimensional deformation of the diaphragm 20 when it is placed; conversely, the more incomplete the stress release of the diaphragm 20 during the preparation process, and the higher the dimensional deformation of the diaphragm 20 when it is placed. The diaphragm 20 of the embodiment of the present invention is prepared by adopting the above-mentioned blended material, so that the stress loss rate of the diaphragm 20 is greater than or equal to 30%. This shows that the stress of the diaphragm 20 is completely released during the molding process, and the dimensional deformation of the diaphragm 20 when it is placed is low. Of course, the stress loss rate is not limited to the above embodiment, and those skilled in the art can set it according to actual needs.

[0048] Optionally, the elongation at break of the diaphragm 20 at room temperature is 110%, 200%, 300%, etc. The stress loss rate is 30%, 33%, 35%, 38%, 40%, 45%, 50%, etc. Of course, the stress loss rate and the elongation at break are not limited to the above embodiments, and those skilled in the art can set them according to actual needs.

[0049] In a specific embodiment of the present invention, the blended material further comprises an amine crosslinking agent, and the amine crosslinking agent comprises at least one of hexamethylenediamine, hexamethylenediamine salt, hexamethylenediamine carbamate, triethylenetetramine, 2,2'-methylenedianiline and di-o-tolylguanidine. The amine crosslinking agent is a compound containing an amino functional group, which can undergo a crosslinking reaction with ACM rubber and AEM rubber to form a crosslinked structure, thereby curing the blended material and improving the mechanical properties, heat resistance and chemical resistance of the blended material. Optionally, the amine crosslinking agent may include any one or a mixture of hexamethylenediamine, hexamethylenediamine salt, hexamethylenediamine carbamate, triethylenetetramine, 2,2'-methylenedianiline and di-o-tolylguanidine. Those skilled in the art can choose according to actual needs. During preparation, after the AEM rubber and the ACM rubber are evenly mixed, an amine crosslinking agent is added. The ternary structure of ethylene-acrylate and acrylate containing carboxylic acid groups and / or epoxy groups can undergo a crosslinking reaction with the amine crosslinking agent in the air to cure and form, and finally form a diaphragm 20. It should be noted that the amine crosslinking agent can undergo a crosslinking reaction with AEM rubber and ACM rubber in the air, and the diaphragm 20 is formed by air pressure molding. Compared with other molding processes, air pressure molding significantly improves the output rate of the diaphragm 20 while maintaining a high yield rate, and the mold cost is low, thereby reducing the production cost of the diaphragm 20.

[0050] In a specific embodiment of the present invention, the mass percentage of the amine cross-linking agent in the blended material is 0.2wt%-5wt%.

[0051] In an embodiment of the present invention, when mixing, the mass of the amine cross-linking agent accounts for 0.2wt%-5wt% of the total mass of the blended material. It should be noted that the less the mass content of the amine cross-linking agent, the insufficient degree of cross-linking of the blended material, and the poor stability of the macromolecular network structure formed by the blended material. When the mass proportion of the amine cross-linking agent in the blended material is less than 0.2wt%, the degree of cross-linking of the diaphragm 20 is insufficient, and the stability of the macromolecular network structure is poor. If the mass content of the amine cross-linking agent is too high, the elongation at break of the diaphragm 20 is too low. In particular, when the mass proportion of the amine cross-linking agent in the blended material is greater than 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 amine cross-linking agent in the blended material is 0.2wt%-5wt%, it can not only ensure that the diaphragm 20 has a sufficient degree of cross-linking, but also make the diaphragm 20 have a higher elongation at break.

[0052] Optionally, the mass proportion of the amine crosslinking agent in the blended material is 0.2wt%, 0.5wt%, 1wt%, 2wt%, 3wt%, 4wt%, 5wt%, etc. Further, the mass proportion of the amine crosslinking agent in the blended material is 0.5wt%-3wt%. Of course, the mass proportion of the amine crosslinking agent in the blended material is not limited to the above embodiments, and those skilled in the art can make a selection according to actual needs.

[0053] In a specific embodiment of the present invention, the diaphragm hardness is 45A-80A; And / or, the glass transition point of the diaphragm 20 is -60°C-10°C.

[0054] In an embodiment of the present invention, the diaphragm 20 satisfies any one of the above conditions or satisfies both of the above conditions at the same time. However, if the hardness of the diaphragm 20 is too high, it is easy to cause the elongation at break of the diaphragm 20 to decrease, and the toughness of the diaphragm 20 is insufficient, and the membrane rupture phenomenon is easy to occur. When the hardness of the diaphragm 20 of the present invention is greater than or equal to 45A, the room temperature damping factor of the diaphragm 20 is greater than or equal to 0.3. When the hardness of the diaphragm 20 is less than or equal to 80A, the diaphragm 20 can maintain sufficient toughness and is not prone to membrane rupture. Therefore, the room temperature damping factor of the diaphragm 20 of the embodiment of the present invention is greater than or equal to 0.3, and the hardness is 45A-80A, which makes the diaphragm 20 significantly reduce polarization and distortion at a larger amplitude, and is not prone to membrane rupture.

[0055] In addition, the glass transition point (i.e., glass transition temperature, Tg) refers to the temperature at which a material changes from a glassy state to a highly elastic state. The glass transition point can be tested according to the ASTM D882 standard. In this embodiment, the glass transition point of the diaphragm 20 is -60°C-10°C, so that the diaphragm 20 can be used for a long time in a low temperature environment without the diaphragm 20 being broken due to vibration stretching.

[0056] Optionally, the hardness of the diaphragm 20 is 45A, 50A, 60A, 70A, 80A, etc. The glass transition point of the diaphragm 20 is -60°C, -50°C, -40°C, -30°C, -20°C, -10°C, 0°C, 10°C, etc. Of course, the hardness and glass transition point of the diaphragm 20 are not limited to the above embodiments, and those skilled in the art can select according to actual needs.

[0057] In a specific embodiment of the present invention, the blended material further includes a reinforcing agent, which is at least one of white carbon black, talcum powder, carbon black, and calcium carbonate, and the mass proportion of the reinforcing agent in the blended material is 5wt%-60wt%.

[0058] In this embodiment, the reinforcing agent is used to improve the mechanical properties of the diaphragm 20, such as tensile strength, hardness, etc. When preparing the diaphragm 20, the reinforcing agent can be one or a mixture of white carbon black, talcum powder, carbon black, and calcium carbonate. Those skilled in the art can select according to actual needs.

[0059] It should be noted that the lower the content of the reinforcing agent, the lower the tensile strength of the diaphragm 20, especially when the mass proportion of the reinforcing agent in the blended material is less than 5wt%, the reinforcing effect on the diaphragm 20 is poor. If the content of the reinforcing agent is too high, for example, when the mass proportion of the reinforcing agent in the blended material is greater than 60wt%, the elongation at break of the diaphragm 20 will decrease significantly, and the toughness of the material is insufficient, resulting in the diaphragm 20 being prone to membrane breakage during vibration. When the mass proportion of the reinforcing agent in the blended material is 5wt%-60wt%, the diaphragm 20 has sufficient tensile strength, elongation at break and toughness.

[0060] Optionally, the mass proportion of the reinforcing agent in the blended material is 5wt%, 10wt%, 20wt%, 30wt%, 40wt%, 50wt%, 60wt%, etc. Of course, the mass proportion of the reinforcing agent in the blended material is not limited to the above embodiments, and those skilled in the art can make a selection according to actual needs.

[0061] In a specific embodiment of the present invention, the blended material also includes an antioxidant, and the antioxidant includes at least one of antioxidant N-445, antioxidant 246, antioxidant 4010, antioxidant SP, antioxidant RD, antioxidant ODA, antioxidant OD, and antioxidant WH-02, and the mass proportion of the antioxidant in the blended material is 0.2wt%-6wt%.

[0062] Specifically, during the use of polymer materials, as time goes by, the molecular chain breaks and generates autocatalytic active free radicals. Autocatalytic active free radicals can accelerate the aging of the polymer materials themselves. Adding an antioxidant to the diaphragm 20 can stop the generation of autocatalytic 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 mixtures of antioxidant N-445, antioxidant 246, antioxidant 4010, antioxidant SP, antioxidant RD, antioxidant ODA, antioxidant OD, and antioxidant WH-02 can be selected as antioxidants. The above antioxidants are all miscible with AEM rubber and ACM rubber, thereby preventing the diaphragm 20 from aging and extending the service life of the diaphragm 20.

[0063] It should be noted that in the blended material, the amount of antioxidant added is too small, for example, when the mass proportion of the antioxidant in the blended material is less than 0.2wt%, it is impossible to prevent the aging of the diaphragm 20 and extend the service life of the diaphragm 20. Too much antioxidant is added, for example, when the mass proportion of the antioxidant in the blended material is greater than 6wt%, the antioxidant cannot be well soluble with AEM rubber and ACM rubber, so that the antioxidant cannot be evenly dispersed in the blended material, resulting in a decrease in the mechanical properties of the diaphragm 20. When the mass proportion of the antioxidant in the blended material is 0.2wt%-6wt%, the antioxidant can effectively extend the service life of the diaphragm 20, and the antioxidant can be evenly dispersed in the blended material, and the prepared diaphragm 20 can maintain good mechanical properties.

[0064] Optionally, the weight percentage of the antioxidant in the blended material is 0.2wt%, 0.5wt%, 1wt%, 2wt%, 3wt%, 4wt%, 5wt%, 6wt%, etc. Further, the weight percentage of the antioxidant in the blended material is 0.5wt%-2wt%. Of course, the weight percentage of the antioxidant in the blended material is not limited to the above embodiments, and those skilled in the art can select according to actual needs.

[0065] In a specific embodiment of the present invention, the room temperature storage modulus of the diaphragm 20 is 2MPa-50Mpa; And / or, the density of the diaphragm 20 is 1.1 g / cm 3 -1.65g / cm3 ; And / or, the thickness of the diaphragm 20 is 20 μm-150 μm.

[0066] In the embodiment of the present invention, the diaphragm 20 satisfies any one of the above conditions, any two of the above conditions, or all three of the above conditions.

[0067] The room temperature storage modulus of the diaphragm 20 of the embodiment of the present invention is 2MPa-50Mpa. The storage modulus is used to characterize the ability of a material to resist elastic deformation. The room temperature storage modulus refers to the amount of energy stored in a material when it is subjected to an external force at room temperature. The room temperature storage modulus can be tested according to the ASTM D882 standard. It should be noted that when the room temperature storage modulus of the diaphragm 20 is too small, for example, less than 2MPa, the strength of the diaphragm 20 is too small, and polarization is prone to occur. When the room temperature storage modulus of the diaphragm 20 is too large, for example, greater than 50MPa, the hardness of the diaphragm 20 is too high, the elongation at break is low, and membrane rupture is prone to occur. When the room temperature storage modulus of the diaphragm 20 is 2MPa-50Mpa, the diaphragm 20 can have both good elasticity and hardness, and membrane rupture is not prone to occur.

[0068] Optionally, the room temperature storage modulus of the diaphragm 20 is 2MPa, 10MPa, 20MPa, 30MPa, 40MPa, 50MPa, etc. Of course, the room temperature storage modulus of the diaphragm 20 is not limited to the above embodiment, and those skilled in the art can set it according to actual needs.

[0069] The density of the diaphragm 20 in the embodiment of the present invention is 1.1 g / cm 3 -1.65g / cm 3 It should be noted that when the density of the diaphragm 20 is too high, for example, greater than 1.65 g / cm 3 When the density of the diaphragm 20 is too small, for example, less than 1.1 g / cm 3 When the density of the diaphragm 20 is 1.1 g / cm 3 -1.65g / cm 3 At the same time, the diaphragm 20 has moderate quality, good mid-frequency performance, and the processing technology of the diaphragm 20 is simple.

[0070] Optionally, the density of the diaphragm 20 is 1.1 g / cm 3 , 1.2g / cm 3 , 1.3g / cm 3 , 1.4g / cm 3 , 1.5g / cm 3 , 1.6g / cm3 , 1.65g / cm 3 Of course, the density of the diaphragm 20 is not limited to the above embodiment, and those skilled in the art can set it according to actual needs.

[0071] The thickness of the diaphragm 20 of the embodiment of the present invention is 20μm-150μm. The diaphragm 20 of the embodiment of the present invention is a single-layer structure. It should be noted that when the thickness of the diaphragm 20 is too low, for example, less than 20μm, the diaphragm 20 is easily deformed during processing, which is not conducive to the processing and molding of the diaphragm 20. When the thickness of the diaphragm 20 is too high, for example, greater than 150μm, the vibration space of the diaphragm 20 is affected, and the diaphragm 20 is easily rubbed against the shell. When the thickness of the diaphragm 20 is 20μm-150μm, it can not only ensure the convenience of processing of the diaphragm 20, but also save the vibration space of the diaphragm 20.

[0072] Optionally, the thickness of the diaphragm 20 is 20 μm, 40 μm, 50 μm, 80 μm, 100 μm, 120 μm, 150 μm, etc. Of course, the thickness of the diaphragm 20 is not limited to the above embodiment, and those skilled in the art can set it according to actual needs.

[0073] According to another embodiment of the present invention, a sound generating device is provided. Figure 2-Figure 3 As shown, the sound-generating device 100 includes the diaphragm 20 of the above embodiment.

[0074] In this example, the sound-generating device 100 may be a sound-generating device such as a speaker unit or a speaker assembly, and those skilled in the art may determine it according to actual conditions, and no specific limitation is made here.

[0075] like Figure 2-Figure 3 As shown, the sound-generating device 100 may include a housing 10, a magnetic circuit system and a vibration system, wherein the magnetic circuit system includes a permanent magnet 40, and the permanent magnet 40 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 arranged 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.

[0076] In this example, the diaphragm 20 may be a folded ring diaphragm. The folded ring diaphragm includes a central portion, a folded ring portion, and a fixed portion connected in sequence from the inside to the outside. The fixed portion is used to connect to the housing 10. The central portion is provided with a dome, and the voice coil 30 is connected to the central portion or the dome.

[0077] In other examples, the diaphragm 20 may also be a planar diaphragm or other structures, which can be determined by those skilled in the art according to actual conditions and is not specifically limited here.

[0078] According to yet another embodiment of the present invention, an electronic device is provided.

[0079] 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 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 repeated here.

[0080] The diaphragm 20 and the sound generating device 100 of the present invention are described in detail below in conjunction with specific embodiments. It should be noted that the following description is only exemplary and does not specifically limit the present invention.

[0081] (I) Retention rate of elongation at break of diaphragm 20 after aging for 168h at 150℃ with different ACM rubber mass contents The thickness of the diaphragm is 85 μm, and the diaphragm is made of a blend of AEM rubber and ACM rubber, wherein the mass content of ACM rubber is the percentage of the mass of ACM rubber to the total mass of ACM rubber and AEM rubber. Among them, the mass contents of ACM rubber are 0wt%, 10wt%, 30wt%, and 50wt%, respectively. The elongation at break retention rate of the diaphragm 20 after aging for 168 hours at 150°C is calculated. The test standard for the elongation at break of the diaphragm 20 is the ASTM D412-2016 standard. The elongation at break retention rate of the diaphragm 20 after aging for 168 hours at 150°C refers to the percentage of the elongation at break of the diaphragm 20 after aging for 168 hours at 150°C to the elongation at break of the diaphragm 20 before aging. The measured data are shown in Table 1. 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 with a composition material that is completely consistent with the diaphragm 20 is selected for relevant tests to characterize the characteristics of the diaphragm. Since the composition material of the sample is completely consistent with that of the diaphragm 20 itself, the measured relevant characteristics of the sample are consistent with the relevant characteristics of the diaphragm 20.

[0082] Table 1 - Retention rate of elongation at break of diaphragm after aging for 168h at 150℃

[0083] As can be seen from Table 1, when the mass content of ACM rubber in the blended material is 0 (i.e., the diaphragm 20 is AEM rubber), the retention rate of the elongation at break of the diaphragm 20 after aging for 168 hours at 150°C is too low, only 43.2%. When the blended material includes ethylene-acrylate rubber and acrylate rubber, since the molecules of acrylate rubber are easy to form hydrogen bonds, the intermolecular force is large and the cohesive energy is high, so the heat resistance of the diaphragm 20 is excellent. When the mass content of ACM rubber reaches greater than or equal to 10wt%, the retention rate of the elongation at break of the diaphragm 20 after aging for 168 hours at 150°C is high, for example, greater than 52%. This makes the diaphragm 20 have good heat resistance. With the increase of the mass content of ACM rubber, the retention rate of the elongation at break of the diaphragm 20 after aging for 168 hours at 150°C gradually increases. However, due to the poor molecular flexibility of ACM rubber, as the number of hydrogen bonds increases, the toughness of the diaphragm 20 will decrease, thereby reducing the elongation at break of the diaphragm 20 and making it easy for the membrane to break. Therefore, the mass content of ACM rubber does not exceed 50wt%.

[0084] (II) Elongation at break and tensile strength of diaphragm 20 at different silica mass contents The thickness of the diaphragm 20 is 85 μm. The diaphragm 20 is made of a blend of AEM rubber and ACM rubber, wherein the mass content of ACM rubber (the ratio of the mass of ACM rubber to the total mass of ACM rubber and AEM rubber) is 35%. The mass contents of white carbon black in the blend are 5wt%, 37wt% and 60wt% respectively. The test standard for the elongation at break and tensile strength of the diaphragm 20 is ASTM D412-2016 standard. The measured elongation at break and tensile strength of different diaphragms 20 are shown in Table 2. 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 with the same composition material as the diaphragm 20 is selected for relevant tests to characterize the characteristics of the diaphragm 20. Since the sample is made of the same composition material as the diaphragm 20 itself, the relevant characteristics of the measured sample are consistent with the relevant characteristics of the diaphragm 20.

[0085] Table 2 - Elongation at break and tensile strength of diaphragm

[0086] As can be seen from Table 2, as the mass content of white carbon black increases, the elongation at break of the diaphragm 20 gradually decreases, and the tensile strength of the diaphragm 20 gradually increases. When the mass content of white carbon black is greater than 60wt%, the elongation at break of the diaphragm 20 is too low to meet the use requirements. When the mass content of white carbon black is less than 5wt%, the tensile strength of the diaphragm 20 is too low and also cannot meet the use requirements. This is because the main component of white carbon black is silicon dioxide. White carbon black is a white amorphous powder, and its surface contains relatively active hydroxyl groups. Due to the strong interaction between the surface of white carbon black and the interface of ACM rubber and AEM rubber, when the material is stressed, the molecular chain is easier to slide on the surface of white carbon black, but it is not easy to detach from it. In this way, the molecular chain and white carbon black form a strong bond that can slide, which increases the tensile strength of the diaphragm 20. However, the reinforcing agent, as a filler, occupies the space of the diaphragm 20, reducing the stretching space of the molecular chain. Therefore, as the mass content of white carbon black increases, the elongation at break of the diaphragm 20 gradually decreases.

[0087] (III) Total harmonic distortion of the sound-generating device of the embodiment of the present invention and the sound-generating device of the comparative example The sound-generating device of the embodiment of the present invention is a micro-speaker. The micro-speaker adopts the diaphragm of the embodiment of the present invention, wherein the diaphragm is a folded ring diaphragm. The folded ring diaphragm includes a central portion, a folded ring portion arranged around the central portion, and an edge portion arranged around the folded ring portion. A reinforcement layer is provided at the central portion. The edge portion is connected to the shell. The thickness of the diaphragm is 70 μm. The diaphragm 20 is made of a blended material consisting of AEM rubber and ACM rubber. The diaphragm is rectangular as a whole. The ratio of the mass of ACM rubber to the total mass of ACM rubber and AEM rubber is 30%, the hardness is 79.9A, the elongation at break retention rate after aging for 168 hours at 150°C is 55.3%, and the damping factor at room temperature is 0.4128. The F0 of the sound-generating device is 911 Hz.

[0088] The diaphragm used in the sound-generating device of comparative example 1 is made of AEM rubber. The diaphragm is a single-layer structure, with a thickness of 70 μm, a hardness of 79.8A, a retention rate of elongation at break after aging for 168 hours at 150°C of 43.2%, and a damping factor of 0.2965 at room temperature. The F0 of the sound-generating device is 912 Hz.

[0089] The structure and size of the sound-generating device of comparative example 1 are the same as those of the sound-generating device of the embodiment of the present invention. The outer dimensions of the diaphragm of comparative example 1 are the same as those of the diaphragm 20 of the embodiment of the present invention.

[0090] According to the above content, the elongation retention rate at break and the damping factor at room temperature of the diaphragm 20 of the embodiment of the present invention after aging for 168 hours at 150°C are significantly higher than the elongation retention rate at break and the damping factor at room temperature of the diaphragm of the comparative example 1 after aging for 168 hours at 150°C. The F0 of the micro-speakers of the embodiment of the present invention and the comparative example 1 are basically the same, that is, the low-frequency loudness of the two is basically the same. The THD curves of the micro-speakers of the embodiment of the present invention and the comparative example 1 are as follows: Figure 4 As shown. The horizontal axis is frequency, unit: Hz; the vertical axis is THD, unit: %. Figure 4 It can be seen that the total harmonic distortion of the micro-speaker of the embodiment of the present invention is lower than that of the micro-speaker of Comparative Example 1. The listening effect of the micro-speaker of the embodiment of the present invention is better.

[0091] In summary, the diaphragm 20 of the embodiment of the present invention is prepared by a blended material including ethylene-acrylate rubber and acrylate rubber, and the ratio of the mass of the acrylate rubber to the total mass of the acrylate rubber and the ethylene-acrylate rubber is 30%. Since the blended material includes ACM rubber and AEM rubber, the damping performance of the diaphragm 20 is improved due to the hydrogen bonds formed by the ester groups and the microscopic phase separation of the material. The room temperature damping factor of the diaphragm reaches 0.4128, which is significantly higher than the room temperature damping factor of the diaphragm 20 of comparative example 1, thereby effectively suppressing the polarization and distortion of the diaphragm 20; and the retention rate of the elongation at break of the diaphragm after aging for 168 hours at 150°C reaches 55.3%, which is significantly higher than the retention rate of the elongation at break of the diaphragm of comparative example 1 after aging for 168 hours at 150°C, so that the diaphragm 20 of the embodiment of the present invention has good heat resistance.

[0092] 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.

[0093] Although some specific embodiments of the present invention have been described in detail by way of example, it will be appreciated 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 will be appreciated by those skilled in the art that the above embodiments may be modified 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 is formed into a single-layer structure, and the diaphragm is prepared from a blended material, wherein the blended material includes ethylene-acrylate rubber and acrylate rubber, wherein the ethylene-acrylate rubber is a ternary structure, and its molecular formula is: ， Wherein, x, y, z are natural numbers; R and R' are alkyl groups; The molecular formula of the acrylic rubber contains carboxylic acid groups and / or epoxy groups; In the blended material, the ratio of the mass of the acrylic rubber to the total mass of the acrylic rubber and the ethylene-acrylate rubber is 10%-50%; the retention rate of the elongation at break of the diaphragm after aging for 168 hours at 150°C is greater than or equal to 52%, and the room temperature damping factor of the diaphragm is greater than or equal to 0.

3.

2. The diaphragm according to claim 1, characterized in that: The elongation at break of the diaphragm at room temperature is greater than or equal to 110%; And / or, the stress loss rate of the diaphragm is greater than or equal to 30%.

3. The diaphragm according to claim 1, characterized in that: The blended material further comprises an amine cross-linking agent, and the amine cross-linking agent comprises at least one of hexamethylenediamine, hexamethylenediamine salt, hexamethylenediamine carbamate, triethylenetetramine, 2,2'-methylenedianiline and di-o-tolylguanidine.

4. The diaphragm according to claim 3, characterized in that: The mass proportion of the amine cross-linking agent in the blended material is 0.2%-5wt%.

5. The diaphragm according to claim 1, characterized in that: The diaphragm hardness is 45A-80A; And / or, the glass transition point of the diaphragm is -60°C-10°C.

6. The diaphragm according to claim 1, characterized in that: The ratio of the mass of the acrylic rubber to the total mass of the acrylic rubber and the ethylene-acrylate rubber is 20%-40%.

7. The diaphragm according to claim 1, characterized in that: The blended material also includes a reinforcing agent, which is at least one of white carbon black, talcum powder, carbon black, and calcium carbonate. The weight proportion of the reinforcing agent in the blended material is 5wt%-60wt%.

8. The diaphragm according to claim 1, characterized in that: The blended material also includes an antioxidant, which includes at least one of antioxidant N-445, antioxidant 246, antioxidant 4010, antioxidant SP, antioxidant RD, antioxidant ODA, antioxidant OD, and antioxidant WH-02, and the weight proportion of the antioxidant in the blended material is 0.2wt%-6wt%.

9. The diaphragm according to claim 1, characterized in that: The room temperature storage modulus of the diaphragm is 2MPa-50Mpa; And / or, the density of the diaphragm is 1.1 g / cm 3 -1.65g / cm 3 ; And / or, the thickness of the diaphragm is 20 μm-150 μm.

10. A sound-generating device, characterized in that: Comprising a diaphragm as described in any one of claims 1-9.

11. An electronic device, characterized in that: Comprising the sound-generating device as claimed in claim 10.

Images