Diaphragm preparation method, diaphragm, and sound-generating device
Through the coating and drying process of ethylene-acrylate rubber and combined with air pressure forming technology, the problem of high compression molding cost of AEM rubber diaphragm is solved, and the thickness uniformity and cost-effectiveness of the diaphragm tape are improved.
Patent Information
- Application Number
- CN202111446785.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2021-11-30
- Publication Date
- 2025-09-02
- Estimated Expiration
- 2041-11-30
AI Technical Summary
In the prior art, the manufacturing cost of AEM rubber diaphragm is high, resulting in an increase in production costs and reducing product profits.
The diaphragm tape is prepared by mixing ethylene-acrylate rubber with polar solvents through the coating and drying process, and the diaphragm is obtained by air pressure forming, avoiding the use of special hot pressing molds.
The thickness and thickness difference of the diaphragm tape is reduced, the thickness uniformity is improved, the production cost is reduced, and the product profit is increased.
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Figure CN116208902B_ABST
Abstract
Description
Technical Field
[0001] The present application belongs to the field of diaphragm technology. Specifically, the present application relates to a method for preparing a diaphragm, a diaphragm obtained by the preparation method, and a sound-generating device including the diaphragm. Background Art
[0002] In the prior art, the diaphragm in a speaker is made of AEM rubber. Due to its limited thickness, the diaphragm can only be formed through compression molding. However, the high manufacturing cost of compression molding increases the production cost of the AEM rubber diaphragm and significantly reduces product profits. Summary of the Invention
[0003] One object of the present application is to provide an improved method for preparing a diaphragm.
[0004] Another object of the present application is to provide a diaphragm.
[0005] Another object of the present application is to provide a sound-generating device.
[0006] According to a first aspect of the present application, a method for preparing a diaphragm is provided, comprising the following steps:
[0007] Ethylene-acrylate raw rubber is uniformly mixed with raw materials consisting of a reinforcing agent and an antioxidant to obtain uncross-linked ethylene-acrylate rubber; the ethylene-acrylate rubber is dissolved in a polar solvent to obtain an initial ethylene-acrylate rubber solution; the initial solution is filtered and defoamed to obtain a coating solution, the solid content of the coating solution is 5% to 50%, and the viscosity of the coating solution is 10mPa·s to 100000mPa·s; the coating solution is inverted on a coating machine, and the coating machine is used to evenly coat the coating solution to obtain a continuously coated material; the coated material is placed in a drying tunnel for drying to obtain a diaphragm strip; the diaphragm strip is air-pressure-formed to cure and cross-link the ethylene-acrylate rubber to form a basic membrane material, and the basic membrane material is cut to obtain a diaphragm of a set shape.
[0008] According to some embodiments of the present application, the polar solvent is at least one of ethyl acetate, toluene, acetone, butanone, tetrahydrofuran, methyl formate, and butyl acetate.
[0009] According to some embodiments of the present application, in the process of dissolving the ethylene-acrylate rubber in the polar solvent, the dissolution temperature is 0°C to 100°C.
[0010] According to some embodiments of the present application, the coating glue is evenly coated on the surface of a base film by the coating machine to obtain the continuously coated material, wherein the base film is a release film or a protective film.
[0011] In some embodiments of the present application, before the diaphragm material strip is pneumatically formed, the preparation method includes: peeling off the base film on the diaphragm material strip.
[0012] According to some embodiments of the present application, the temperature of the drying tunnel is 30° C. to 140° C., and the time the material stays in the drying tunnel is 0.2 min to 30 min.
[0013] According to some embodiments of the present application, the tensile strength of the diaphragm material strip is between 3 MPa and 35 MPa, and the elongation at break of the diaphragm material strip is ≥50%.
[0014] According to some embodiments of the present application, the thickness of the diaphragm material strip is 10 μm to 300 μm, and the tolerance of the thickness of the diaphragm material strip at different positions is ±5 μm.
[0015] According to some embodiments of the present application, the hardness of the diaphragm material strip is 35A to 90A.
[0016] According to some embodiments of the present application, the ethylene-acrylate raw rubber comprises at least one of an ethylene-acrylate copolymer and an ethylene-acrylate-carboxylic acid copolymer.
[0017] According to some embodiments of the present application, the raw material further includes a vulcanizing agent, and the vulcanizing agent is at least one of an ammonia vulcanizing agent and a peroxide vulcanizing agent.
[0018] According to some embodiments of the present application, the ammonia vulcanizing agent includes at least one of hexamethylenediamine, hexamethylenediamine carbamate, triethylenetetramine, diphenylamine and di-o-tolylguanidine; the peroxide cross-linking agent includes at least one of 1,3-1,4-di(tert-butylperoxyisopropyl)benzene, diisopropyl benzene peroxide, 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane, tert-butylisopropyl peroxide, 2,5-dimethyl-2,5-bis(tert-butylperoxy)-3-hexyne, 4,4'-bis(tert-butylperoxy) valerate, 1,1'-bis(tert-butylperoxy)-3,3,5-trimethylcyclohexane and 2,4-dichlorobenzoyl peroxide.
[0019] In some embodiments of the present application, the vulcanizing agent accounts for 0.15 wt% to 5 wt% of the weight of the ethylene-acrylate rubber.
[0020] According to some embodiments of the present application, the reinforcing agent is at least one of carbon black, white carbon black, talc, calcium carbonate, barium sulfate, organic montmorillonite, unsaturated carboxylic acid metal salt, and hollow inorganic microbeads; 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.
[0021] In some embodiments of the present application, the reinforcing agent accounts for 2 wt% to 60 wt% of the weight of the ethylene-acrylate rubber, and the antioxidant accounts for 0.5 wt% to 5 wt% of the weight of the ethylene-acrylate rubber.
[0022] Another aspect of the present application provides a diaphragm, including a diaphragm prepared by the method of any of the above embodiments.
[0023] Another aspect of the present application provides a sound-producing device, including a vibration system and a magnetic circuit system coordinated with the vibration system, wherein the vibration system includes a diaphragm and a voice coil coupled to one side of the diaphragm, and the magnetic circuit system drives the voice coil to vibrate to drive the diaphragm to produce sound, and the diaphragm is a diaphragm prepared by the method described in any of the above embodiments.
[0024] Another aspect of the present application provides a sound-producing device, including a shell and a magnetic circuit system and a vibration system arranged in the shell, the vibration system including a voice coil, a first diaphragm and a second diaphragm, the top of the voice coil is connected to the first diaphragm, the magnetic circuit system drives the voice coil to vibrate to drive the first diaphragm to produce sound, the two ends of the second diaphragm are respectively connected to the shell and the bottom of the voice coil, and the second diaphragm is a diaphragm prepared by the method described in any of the above embodiments.
[0025] One of the technical effects of the present application is that the diaphragm strip is obtained by dissolving, coating, drying, etc. AEM rubber is subjected to air pressure molding to obtain the required diaphragm, which not only reduces the thickness of the diaphragm strip, but also reduces the thickness difference at different positions on the diaphragm strip, thereby improving the thickness uniformity of the diaphragm strip. Moreover, the diaphragm strip is made by the coating process, and there is no need to use a special hot pressing mold for molding, thereby reducing production costs, reducing the price of the diaphragm, and increasing product profits.
[0026] Other features and advantages of the present application will become apparent from the following detailed description of exemplary embodiments of the present application with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS
[0027] The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate embodiments of the application and, together with the description, serve to explain the principles of the application.
[0028] Figure 1 1 is a stress-strain curve diagram of Example 1 and Comparative Example 1 provided in this application;
[0029] Figure 2 It is a stress-strain curve diagram of Example 2 and Comparative Example 2 provided in this application.
[0030] Figure 3 Schematic diagram of the overall structure of the sound-generating device according to an embodiment of the present application;
[0031] Figure 4 is a schematic diagram of a partial structure of a sound-generating device according to an embodiment of the present application;
[0032] Figure 5 is a cross-sectional view of a sound-generating device according to an embodiment of the present application;
[0033] Figure 6 1 is an exploded view of a sound-generating device according to an embodiment of the present application.
[0034] Reference numerals
[0035] Sound-generating device 100;
[0036] Housing 10; voice coil 11; first diaphragm 12; second diaphragm 13; magnetic circuit system 14;
[0037] Diaphragm 15 ; surround 151 ; dome 152 . DETAILED DESCRIPTION
[0038] Various exemplary embodiments of the present application will now be described in detail with reference to the accompanying drawings. It should be noted that unless otherwise specifically stated, the relative arrangements of components and steps, numerical expressions and numerical values set forth in these embodiments do not limit the scope of the present application.
[0039] The following description of at least one exemplary embodiment is merely illustrative in nature and is in no way intended to limit the present disclosure, its application, or uses.
[0040] 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.
[0041] 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.
[0042] 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.
[0043] The method for preparing a diaphragm according to an embodiment of the present application includes the following steps:
[0044] The ethylene-acrylate raw rubber is uniformly mixed with raw materials consisting of a reinforcing agent and an antioxidant to obtain an uncrosslinked ethylene-acrylate rubber, that is, the ethylene-acrylate raw rubber is kneaded with the reinforcing agent and the antioxidant to form the uncrosslinked ethylene-acrylate rubber;
[0045] dissolving ethylene-acrylate rubber in a polar solvent to obtain an initial ethylene-acrylate rubber solution;
[0046] The initial glue solution is filtered and defoamed to obtain a coating glue solution, wherein the coating glue solution has a solid content of 5% to 50% and a viscosity of 10 mPa·s to 100,000 mPa·s;
[0047] The coating glue liquid is inverted on the coating machine, and the coating glue liquid is evenly coated by the coating machine to obtain a continuously coated material. For example, the coating glue liquid can be inverted on the coating machine, and the coating glue liquid is evenly and continuously coated on the surface of the base film from the coating head position.
[0048] The coated material is placed in a drying tunnel for drying to obtain a diaphragm material strip;
[0049] The diaphragm material strip is air-pressed to form a base membrane material so that the ethylene-acrylate rubber is cured and cross-linked to form the base membrane material, and the base membrane material is cut to obtain a diaphragm of a set shape.
[0050] In other words, the method for preparing the diaphragm of the present application mainly includes two steps: first, preparing a diaphragm strip, and then preparing a diaphragm through the diaphragm strip.
[0051] When preparing the diaphragm material strip, ethylene-acrylate (AEM) rubber can first be obtained by crosslinking raw materials. The raw materials may include ethylene-acrylate raw rubber, a reinforcing agent, and an antioxidant. The AEM rubber is then dissolved in a polar solvent to obtain an initial AEM rubber solution. The resulting initial AEM rubber solution is then subjected to coating and drying steps to prepare the diaphragm material strip. It should be noted that the raw materials include ethylene-acrylate raw rubber, a reinforcing agent, and an antioxidant. During preparation, the ethylene-acrylate raw rubber, the reinforcing agent, and the antioxidant can be added to an internal mixer or an open mixer and uniformly mixed by shearing in the internal mixer or open mixer to obtain the AEM rubber. The ethylene-acrylate raw rubber is unvulcanized raw rubber. Prior to the step of dissolving the AEM rubber solution, the AEM rubber is kept in an unvulcanized state to prevent the AEM rubber from becoming insoluble due to crosslinking.
[0052] Before the coating process is carried out, the initial AEM rubber glue solution is filtered and defoamed to obtain a coating glue solution. The solid content of the obtained coating glue solution is 5% to 50%, and the viscosity of the coating glue solution is 10mPa·s to 100000mPa·s. Among them, the calculation method of the solid content is (mass of AEM rubber / mass of initial glue solution) × 100%. It should be noted that the solid content of the coating glue solution of the embodiment of the present application should not be too high or too low. When the solid content is too low, the fluidity of the coating glue solution coated on the base film will be higher, resulting in a worse uniformity in the thickness of the coated diaphragm material strip. Excessively high solid content will result in extremely high viscosity and poor fluidity, which will lead to problems such as a long defoaming process time, poor fluidity on the base film, and a slow rate of solvent volatilization in the drying tunnel. When the solid content of the coating glue is 5% to 50% and the viscosity of the coating glue is 10mPa·s to 100,000mPa·s, not only can the coating efficiency be improved, but also the quality of the coated diaphragm material can be improved. Optionally, the solid content of the initial glue or the coating glue can be 5%, 10%, 12%, 15%, 20%, 30%, 40%, 45%, 50%, etc.
[0053] During the coating process, the coating glue is inverted on the coating machine, and then the coating glue is evenly coated by the coating machine to obtain a continuously coated material. Specifically, the coating glue can be evenly and continuously coated on the surface of the base film from the coating head position to obtain a continuously coated material.
[0054] During the drying process, the material is sent into a drying tunnel for heating and drying, thereby volatilizing the solvent on the surface of the material to obtain a diaphragm material strip.
[0055] When preparing the diaphragm through the diaphragm material strip, the diaphragm material strip is air pressure formed and cut. During the air pressure forming, under the action of the die head temperature, the ethylene-acrylate rubber is cured and cross-linked to form a basic membrane material. The basic membrane material can then be cut to obtain a diaphragm of a set shape. It should be noted that, compared with the existing AEM rubber compound, since the diaphragm material strip of the embodiment of the present application has undergone the process of stirring, dispersing, and dissolving, the various fillers inside it are more evenly dispersed at the molecular level, and the prepared diaphragm material strip does not have local defects caused by poor material uniformity. Therefore, under the same material hardness, the diaphragm material strip of the present application has more excellent mechanical properties and has relatively excellent mechanical strength. In addition, the thickness tolerance of the diaphragm material strip of the present application at different positions is small, and the thickness uniformity is high.
[0056] Therefore, according to the preparation method of the diaphragm of the embodiment of the present application, the diaphragm strip is obtained by dissolving, coating, drying and other steps of AEM rubber, and the required diaphragm is obtained by air pressure molding. This not only can reduce the thickness of the diaphragm strip, but also can reduce the thickness difference between different positions on the diaphragm strip, improve the thickness uniformity of the diaphragm strip, reduce production costs, and thus reduce the price of the diaphragm.
[0057] According to one embodiment of the present application, the polar solvent is at least one of ethyl acetate, toluene, acetone, butanone, tetrahydrofuran, methyl formate, and butyl acetate. By using the above polar solvents, the AEM rubber can be effectively dissolved.
[0058] In some specific embodiments of the present application, when dissolving the ethylene-acrylate rubber in a polar solvent, the dissolution temperature is 0°C to 100°C, inclusive. Preferably, the dissolution temperature is 20°C to 70°C, inclusive. By adopting a dissolution temperature within this range, the AEM rubber can be uniformly dispersed in the solvent to obtain an initial AEM rubber solution. Alternatively, the dissolution temperature of the ethylene-acrylate rubber can be 10°C, 20°C, 30°C, 40°C, 50°C, 60°C, 70°C, 80°C, 90°C, or 100°C.
[0059] It should be noted that if the dissolution temperature is below 0°C, the solvent's solubility is poor and the AEM rubber cannot be effectively and evenly dispersed. If the dissolution temperature is above 100°C, there is a risk of vulcanization during the dissolution process, which can easily lead to AEM solidification.
[0060] According to one embodiment of the present application, a coating glue is evenly coated on the surface of a base film by a coating machine to obtain a continuously coated material, wherein the base film is a release film or a protective film. During coating, the coating glue is evenly coated on the surface of the release film or the protective film by a coating machine, which is conducive to uniform coating and reduces the thickness difference at each position.
[0061] In some embodiments of the present application, before the diaphragm strip is air-pressed and formed, the preparation method includes: peeling off the base film on the diaphragm strip, thereby preventing the base film from affecting the performance of the formed base film material during the hot pressing process.
[0062] In some specific embodiments of the present application, the temperature of the drying tunnel is 30° C. to 140° C., preferably 50° C. to 120° C. The time the material stays in the drying tunnel is 0.2 min to 30 min, preferably 0.5 min to 20 min.
[0063] It should be noted that when the temperature in the drying tunnel is lower than 30°C, the solvent in the coating film takes a long time to evaporate, which seriously affects production efficiency, and the prepared diaphragm material has a high amount of residual solvent, which is not conducive to the subsequent preparation of the diaphragm. When the temperature is higher than 140°C, the coating film is at risk of premature cross-linking reaction, which is not conducive to the stability of the material. When the temperature of the drying tunnel is within the range of 30°C to 140°C, it can not only accelerate the volatilization of the solvent, but also avoid premature cross-linking reaction of the coating film. Optionally, the temperature of the drying tunnel can be 30°C, 40°C, 50°C, 60°C, 70°C, 80°C, 90°C, 100°C, 110°C, 120°C, 130°C and 140°C.
[0064] According to one embodiment of the present application, the tensile strength of the diaphragm strip is 3MPa to 35MPa, preferably 5MPa to 30MPa. Optionally, the tensile strength of the diaphragm strip can be 3MPa, 5MPa, 10MPa, 13MPa, 15MPa, 20MPa, 30MPa, 35MPa, etc.
[0065] When the tensile strength is less than 3 MPa, the diaphragm prepared according to the method of this application is prone to excessive stretching and failure to recover during vibration. When the tensile strength is greater than 35 MPa, the amplitude and loudness decrease when the power is applied at the same voltage. When the tensile strength of the diaphragm strip is between 3 MPa and 35 MPa, it not only facilitates the stretching of the diaphragm, but also avoids a decrease in amplitude.
[0066] According to one embodiment of the present application, the elongation at break of the diaphragm material strip is ≥50%, preferably ≥80%.
[0067] The diaphragm material strip obtained by the method according to the embodiment of the present application has good flexibility, for example, the elongation at break is ≥50%. This makes the vibration displacement of the diaphragm of the loudspeaker larger, the loudness greater, and the reliability and durability are also good. As the flexibility of the material is better and the elongation at break is greater, the ability of the diaphragm of the loudspeaker to resist damage is stronger. When the diaphragm of the loudspeaker vibrates in a large amplitude state, the material produces a large strain, and there is a risk of membrane folding, membrane cracking or membrane breaking when vibrating for a long time. When the elongation at break of the diaphragm material strip is ≥50%, the diaphragm of the loudspeaker prepared by the diaphragm material strip has good flexibility, which reduces the risk of the diaphragm being damaged.
[0068] According to one embodiment of the present application, the thickness of the diaphragm material strip is 10μm to 300μm, preferably 25μm to 200μm. The tolerance of the thickness of the diaphragm material strip at different positions is ±5μm. It can be seen that the tolerance of the thickness of the diaphragm material strip at different positions according to the embodiment of the present application is small, and the thickness uniformity is good. Therefore, the diaphragm prepared by pneumatic molding of the diaphragm material strip has good thickness uniformity, and there is no polarization problem caused by uneven thickness, and there is no problem of local over-stretching.
[0069] According to one embodiment of the present application, the hardness of the diaphragm material strip is 35A~90A, preferably 40A~80A. Among them, the F0 of the speaker is proportional to the modulus and thickness, and the modulus of rubber is proportional to its hardness, so the hardness is used instead of its modulus. In order to obtain full bass and comfortable listening experience, the diaphragm should have sufficient stiffness and damping while the speaker has a lower F0. Preferably, the hardness of the diaphragm material strip is 40A~80A. The thickness of the speaker diaphragm is 20μm~200μm. This enables the F0 of the speaker to reach 150Hz~1500Hz. That is, the low-frequency performance of the speaker obtained according to the embodiment of the present application is excellent.
[0070] In some specific embodiments of the present application, the ethylene-acrylate raw rubber comprises at least one of an ethylene-acrylate copolymer and an ethylene-acrylate-carboxylic acid copolymer. In other words, the ethylene-acrylate raw rubber of the present application comprises an ethylene-acrylate copolymer and / or an ethylene-acrylate-carboxylic acid copolymer.
[0071] According to one embodiment of the present application, the raw material further includes a vulcanizing agent, and the vulcanizing agent is at least one of an ammonia vulcanizing agent and a peroxide vulcanizing agent.
[0072] In some specific embodiments of the present application, the ammonia vulcanizing agent is an amine cross-linking agent including at least one of hexamethylenediamine, hexamethylenediamine carbamate, triethylenetetramine, diphenylamine and di-o-tolylguanidine; the peroxide cross-linking agent includes at least one of 1,3-1,4-di(tert-butylperoxyisopropyl)benzene, diisopropyl benzene peroxide, 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane, tert-butyl isopropyl peroxide, 2,5-dimethyl-2,5-bis(tert-butylperoxy)-3-hexyne, 4,4'-bis(tert-butylperoxy) valerate, 1,1'-bis(tert-butylperoxy)-3,3,5-trimethylcyclohexane and 2,4-dichlorobenzoyl peroxide.
[0073] According to one embodiment of the present application, the vulcanizing agent accounts for 0.15wt% to 5wt% of the weight of the ethylene-acrylate rubber, which not only improves the vulcanization efficiency but also improves the heat resistance and other properties of the rubber. Alternatively, the percentage of the vulcanizing agent in the total weight of the ethylene-acrylate rubber can be 0.15wt%, 0.5wt%, 1wt%, 1.5wt%, 2wt%, 2.5wt%, 3wt%, 3.5wt%, 4wt%, 4.5wt% and 5wt%.
[0074] According to one embodiment of the present application, the reinforcing agent is at least one of carbon black, white carbon black, talc, calcium carbonate, barium sulfate, organic montmorillonite, unsaturated carboxylic acid metal salt, and hollow inorganic microbeads; 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.
[0075] In some specific embodiments of the present application, the reinforcing agent accounts for 2wt% to 60wt% of the weight of the ethylene-acrylate rubber. By adopting the content of the reinforcing agent within this range, the strength of the rubber can be improved. Alternatively, the percentage of the reinforcing agent in the total weight of the ethylene-acrylate rubber can be 2wt%, 10wt%, 20wt%, 30wt%, 40wt%, 50wt% and 60wt%. The antioxidant accounts for 0.5wt% to 5wt% of the weight of the ethylene-acrylate rubber. By adopting the content of the antioxidant within this range, a protective effect can be achieved, extending the service life of the rubber. Alternatively, the percentage of the antioxidant in the total weight of the ethylene-acrylate rubber can be 0.5wt%, 1wt%, 1.5wt%, 2wt%, 2.5wt%, 3wt%, 3.5wt%, 4wt%, 4.5wt% and 5wt%.
[0076] The present application also discloses a diaphragm, which is prepared according to the method of any of the above embodiments. Since the diaphragm is prepared by air pressure forming, the cost of the diaphragm can be reduced.
[0077] like Figure 3 and Figure 4 As shown, the sound-generating device includes a diaphragm 15 prepared according to the above-described embodiment of the present application. The diaphragm 15 can be composed of a rim portion 151 and a dome portion 152. A microporous polyurethane elastomer film layer can be applied to the rim portion 151 of the diaphragm. Those skilled in the art can make corresponding adjustments based on actual product requirements, such as making the rim portion 151 convex toward the voice coil 11, positioning the dome portion 152 on the lower surface of the rim portion 151, and adding a centering support to the vibration system.
[0078] like Figure 5 and Figure 6As shown, the sound-producing device 100 according to the third embodiment of the present application includes a shell 10 and a magnetic circuit system 14 and a vibration system arranged in the shell 10. The vibration system includes a voice coil 11, a first diaphragm 12 and a second diaphragm 13. The top of the voice coil 11 is connected to the first diaphragm 12. The magnetic circuit system 14 drives the voice coil 11 to vibrate to drive the first diaphragm 12 to produce sound. The two ends of the second diaphragm 13 are respectively connected to the bottom of the shell 10 and the voice coil 11. The second diaphragm 13 is the diaphragm of the above embodiment.
[0079] That is, the sound-generating device 100 according to the embodiment of the present application may further include two diaphragms prepared according to the above-described embodiment of the present application, namely, a first diaphragm 12 and a second diaphragm 13. The first diaphragm 12 can be used to vibrate and produce sound, and the second diaphragm 13 can be used to balance the vibration of the voice coil 11. Specifically, when the sound-generating device 100 is in operation, after the voice coil 11 is energized, the magnetic field force of the magnetic circuit system 14 causes the voice coil 11 to vibrate up and down, thereby driving the first diaphragm 12 to vibrate. The vibration of the first diaphragm 12 can produce sound. The second diaphragm 13 can also vibrate up and down following the voice coil 11. Since the two ends of the second diaphragm 13 are respectively connected to the housing 10 and the bottom of the voice coil 11, the second diaphragm 13 can balance the vibration of the voice coil 11, prevent polarization of the voice coil 11, and thus improve the sound quality of the sound-generating device 100.
[0080] It should be noted that the first diaphragm 12 and the second diaphragm 13 may simultaneously adopt the diaphragms of the above embodiment of the present application, or one of the first diaphragm 12 and the second diaphragm 13 may adopt the diaphragm of the above embodiment of the present application. The present application does not impose any specific restrictions on this.
[0081] The following describes in detail the method for preparing the diaphragm according to the embodiment of the present application and the obtained diaphragm in conjunction with specific embodiments.
[0082] Example 1
[0083] (1) 100 parts of ethylene-acrylate rubber, 53 parts of reinforcing agent, 2 parts of antioxidant, 2 parts of vulcanizing agent and 2 parts of vulcanization accelerator were weighed as raw materials and mixed to produce AEM rubber with a hardness of 65A, hereinafter referred to as AEM-65.
[0084] (2) The AEM-65 obtained in step (1) was placed in a solvent of ethyl acetate and toluene to obtain an initial adhesive solution, wherein the mass ratio of ethyl acetate to toluene was 5:1 and the solid content of the initial adhesive solution was 15 wt %. After stirring and dispersing for 50 h, the initial adhesive solution was filtered and allowed to stand for defoaming to obtain an AEM-65 coating adhesive solution with a viscosity of 5200 mPa·s.
[0085] (3) coating the AEM-65 coating glue obtained in step (2) evenly and continuously on the surface of the release film from the coating head position, and the continuously coated material enters the drying tunnel to dry the solvent, the drying tunnel temperature is 90 ° C, and the baking time in the drying tunnel is 6 minutes;
[0086] (4) Prepare a 100 μm thick diaphragm strip
[0087] 50g of folded diaphragm material strip was vulcanized using a flat plate vulcanizer to obtain a vulcanized film of 100mm×60mm×0.3mm, where:
[0088] The first stage vulcanization conditions are: temperature 170℃, time 10min, pressure 10MPa,
[0089] The second-stage vulcanization conditions are: temperature 180°C, time 4h, and a two-stage vulcanized film is obtained.
[0090] The tensile performance test of the two-stage vulcanized rubber sample was carried out under the following conditions: the test was carried out in accordance with the ASTM D412-2016 test standard. Figure 1 As shown, from Figure 1 It can be seen that the coordinate value of the highest point of the stress-strain curve of the two-stage vulcanized rubber sheet obtained in Example 1 is (363, 18.3), that is, the tensile strength of the two-stage vulcanized rubber sheet obtained in Example 1 reaches 18.3 MPa, and the elongation at break is 363%.
[0091] Example 2
[0092] (1) 100 parts of ethylene-acrylate rubber, 37 parts of reinforcing agent, 2 parts of antioxidant, 1.1 parts of vulcanizing agent, and 1.5 parts of vulcanization accelerator were weighed as raw materials and mixed to produce AEM rubber with a hardness of 50A, hereinafter referred to as AEM-50.
[0093] (2) The AEM-50 obtained in step (1) was placed in a solvent of ethyl acetate and toluene to obtain an initial adhesive solution, wherein the ratio of butanone to toluene was 5:1 and the solid content of the initial adhesive solution was 20 wt %. After stirring and dispersing for 50 h, the initial adhesive solution was filtered and allowed to stand for defoaming to obtain an AEM-50 coating adhesive solution with a viscosity of 6300 mPa·s.
[0094] (3) coating the AEM-50 coating glue obtained in step (2) evenly and continuously on the surface of the release film from the coating head position, and the continuously coated material enters the drying tunnel to dry the solvent, the drying tunnel temperature is 75 ° C, and the baking time in the drying tunnel is 7 minutes;
[0095] (4) Prepare a 100 μm thick diaphragm strip.
[0096] 50g of folded diaphragm material strip was vulcanized using a flat plate vulcanizer to obtain a vulcanized film of 100mm×60mm×0.3mm, where:
[0097] The first stage vulcanization conditions are: temperature 170℃, time 10min, pressure 10MPa,
[0098] The second-stage vulcanization conditions are: temperature 180°C, time 4h, and a two-stage vulcanized film is obtained.
[0099] The tensile performance test of the two-stage vulcanized rubber sample was carried out under the following conditions: the test was carried out in accordance with the ASTM D412-2016 test standard. Figure 2 As shown, from Figure 2 It can be seen that the coordinate value of the highest point of the stress-strain curve of the two-stage vulcanized rubber sheet obtained in Example 2 is (403, 12.9), that is, the tensile strength of the two-stage vulcanized rubber sheet obtained in Example 2 reaches 12.9 MPa, and the elongation at break is 403%.
[0100] Comparative Example 1
[0101] 100 parts of ethylene-acrylate raw rubber, 53 parts of reinforcing agent, 2 parts of antioxidant, 2 parts of vulcanizing agent and 2 parts of vulcanization accelerator were weighed as raw materials and mixed into a rubber compound with a hardness of 65A.
[0102] The tensile performance test of the sample of the mixed rubber of Example 1 was carried out under the following conditions: the test was carried out in accordance with the ASTM D412-2016 test standard. Figure 1 As shown, from Figure 1 It can be seen that the coordinate value of the highest point of the stress-strain curve of the rubber mix obtained in Comparative Example 1 is (275, 16.5), that is, the tensile strength of the rubber mix obtained in Comparative Example 1 is 16.5 MPa, and the elongation at break is 275%.
[0103] Comparative Example 2
[0104] 100 parts of ethylene-acrylate raw rubber, 37 parts of reinforcing agent, 2 parts of antioxidant, 1.1 parts of vulcanizing agent and 1.5 parts of vulcanization accelerator were weighed as raw materials and mixed into a rubber compound with a hardness of 50A.
[0105] The tensile performance test was carried out on the sample of the mixed rubber of Example 2. The tensile performance test conditions were as follows: the test was carried out in accordance with the ASTM D412-2016 test standard. Figure 1 As shown, from Figure 1 It can be seen that the coordinate value of the highest point of the stress-strain curve of the rubber mix obtained in Comparative Example 2 is (351, 11.8), that is, the tensile strength of the rubber mix obtained in Comparative Example 2 is 11.8 MPa, and the elongation at break is 351%.
[0106] By comparing Example 1 with Comparative Example 1, the tensile strength of Example 1 is greater than that of the comparative example, and the elongation at break of Example 1 is greater than that of the comparative example 1. It can be seen that the mechanical properties of the coated and molded diaphragm material strip in Example 1 are much higher than the mechanical properties of the mixed rubber in Comparative Example 1.
[0107] By comparing Example 2 with Comparative Example 2, the tensile strength of Example 2 is greater than that of the comparative example, and the elongation at break of Example 2 is greater than that of the comparative example 2. It can be seen that the mechanical properties of the coated and molded diaphragm material strip in Example 2 are much higher than the mechanical properties of the mixed rubber in Comparative Example 2.
[0108] In summary, according to the method for preparing the diaphragm of the embodiment of the present application, a diaphragm material strip with uniform thickness is obtained by adopting a scheme of combining dissolution and coating, which reduces the production cost of the diaphragm and improves the uniformity of the thickness distribution of the diaphragm.
[0109] Although some specific embodiments of the present application have been described in detail by way of examples, it should be understood by those skilled in the art that the above examples are for illustration only and are not intended to limit the scope of the present application. It should be understood by those skilled in the art that the above embodiments may be modified without departing from the scope and spirit of the present application. The scope of the present application is defined by the appended claims.
Claims
1. A method for preparing a diaphragm, characterized in that: The following steps are involved: The raw material of ethylene-acrylate rubber is mixed evenly with a reinforcing agent and an antioxidant to obtain an uncrosslinked ethylene-acrylate rubber; dissolving the ethylene-acrylate rubber in a polar solvent to obtain an initial ethylene-acrylate rubber solution; The initial glue solution is filtered and defoamed to obtain a coating glue solution, wherein the coating glue solution has a solid content of 5% to 50% and a viscosity of 10 mPa·s to 100,000 mPa·s; The coating glue is invertedly placed on a coating machine, and the coating glue is evenly coated on the surface of a base film by the coating machine to obtain a continuously coated material, wherein the base film is a release film or a protective film, and the coating glue is evenly coated on the surface of the base film by the coating machine to obtain a continuously coated material; The coated material is placed in a drying tunnel for drying to obtain a diaphragm material strip, the tensile strength of the diaphragm material strip is between 3MPa and 35MPa, and the elongation at break of the diaphragm material strip is ≥50%; the base film on the diaphragm material strip is peeled off, and the diaphragm material strip is air-pressure-formed to allow the ethylene-acrylate rubber to solidify and cross-link to form a basic film material, and the basic film material is cut to obtain a diaphragm of a set shape.
2. The method according to claim 1, characterized in that The polar solvent is at least one of ethyl acetate, toluene, acetone, butanone, tetrahydrofuran, methyl formate, and butyl acetate.
3. The method according to claim 1, characterized in that In the process of dissolving the ethylene-acrylate rubber in the polar solvent, the dissolution temperature is 0°C to 100°C.
4. The method according to claim 1, wherein The temperature of the drying tunnel is 30° C. to 140° C., and the time for the material to remain in the drying tunnel is 0.2 min to 30 min.
5. The method according to claim 1, wherein The thickness of the diaphragm material strip is 10 μm to 300 μm, and the thickness tolerance of the diaphragm material strip at different positions is ±5 μm.
6. The method according to claim 1, wherein The hardness of the diaphragm material strip is 35A-90A.
7. The method according to claim 1, characterized in that The ethylene-acrylate raw rubber comprises at least one of an ethylene-acrylate copolymer and an ethylene-acrylate-carboxylic acid copolymer.
8. The method according to claim 1, characterized in that The raw materials further include a vulcanizing agent, which is at least one of an ammonia vulcanizing agent and a peroxide vulcanizing agent.
9. The method according to claim 8, characterized in that The ammonia vulcanizing agent includes at least one of hexamethylenediamine, hexamethylenediamine carbamate, triethylenetetramine, ethylenediphenylamine and di-o-tolylguanidine; The peroxide vulcanizing agent includes at least one of 1,3-1,4-di(tert-butylperoxyisopropyl)benzene, diisopropyl benzene peroxide, 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane, tert-butyl isopropyl benzene peroxide, 2,5-dimethyl-2,5-bis(tert-butylperoxy)-3-hexyne, 4,4'-bis(tert-butylperoxy) valerate, 1,1'-bis(tert-butylperoxy)-3,3,5-trimethylcyclohexane and 2,4-dichlorobenzoyl peroxide.
10. The method according to claim 9, characterized in that The vulcanizing agent accounts for 0.15 wt % to 5 wt % of the weight of the ethylene-acrylate rubber.
11. The method according to claim 1, wherein The reinforcing agent is at least one of carbon black, white carbon black, talc, calcium carbonate, barium sulfate, organic montmorillonite, unsaturated carboxylic acid metal salt, and hollow inorganic microspheres; 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.
12. The method according to claim 11, characterized in that The reinforcing agent accounts for 2 wt % to 60 wt % of the weight of the ethylene-acrylate rubber, and the antioxidant accounts for 0.5 wt % to 5 wt % of the weight of the ethylene-acrylate rubber.
13. A diaphragm, characterized in that: The diaphragm is a diaphragm prepared by the method according to any one of claims 1-12.
14. A sound-generating device, characterized in that: It includes a vibration system and a magnetic circuit system coordinated with the vibration system, the vibration system includes a diaphragm and a voice coil coupled to one side of the diaphragm, the magnetic circuit system drives the voice coil to vibrate to drive the diaphragm to make sound, and the diaphragm is a diaphragm according to claim 13.
15. A sound-generating device, characterized in that: It includes a shell and a magnetic circuit system and a vibration system arranged in the shell, the vibration system includes a voice coil, a first diaphragm and a second diaphragm, the top of the voice coil is connected to the first diaphragm, the magnetic circuit system drives the voice coil to vibrate to drive the first diaphragm to make sound, the two ends of the second diaphragm are respectively connected to the shell and the bottom of the voice coil, and the second diaphragm is the diaphragm of claim 13.
Citation Information
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