Diaphragm and preparation method thereof, and micro loudspeaker

Abstract

The invention relates to a vibrating diaphragm, a preparation method thereof and a miniature loudspeaker, the vibrating diaphragm is used for a sounding device to realize vibration sounding, and the vibrating diaphragm is characterized in that the vibrating diaphragm is made of liquid silica gel; the liquid silica gel comprises the following components in percentage by mass: 50%-90% of polydimethylsiloxane containing vinyl, 0.5%-10% of organopolysiloxane containing silicon and hydrogen and 0.01%-5% of a catalyst. Compared with the prior art, the vibrating diaphragm is prepared in an air pressure forming mode, the vibrating diaphragm made of the liquid silica gel is good in low temperature resistance and high temperature resistance, the problem that the liquid silica gel overflows in the conventional hot-pressing and injection molding process is solved, the production efficiency is improved, the sensitivity of a micro loudspeaker applying the vibrating diaphragm at the low temperature can be improved, and the service life of the micro loudspeaker is prolonged. And the product stability is improved.

Description

Technical Field

[0001] The present invention is applicable to the technical field of loudspeakers, and particularly relates to a diaphragm, a preparation method thereof, and a micro loudspeaker.

Background Art

[0002] With the requirements of high power, high low-temperature resistance, and high sound quality for micro loudspeakers, diaphragms made of thermosetting elastomers have been increasingly widely used.

[0003] Conventional thermosetting rubbers, including but not limited to acrylate rubber, ethylene-acrylic rubber copolymer, nitrile rubber, hydrogenated nitrile rubber, ethylene-vinyl acetate copolymer, and butyl rubber, have relatively high glass transition temperatures. As a result, the stiffness of the diaphragms made therefrom increases sharply at low temperatures, leading to an increase in the compliance (Cms) of the vibration system and the resonance frequency (F0) of the loudspeaker in a low-temperature environment, a sharp decrease in sensitivity, and a decrease in product stability. In contrast, liquid silicone has become an excellent material for low-temperature resistance because of the small intermolecular force of the silicon-oxygen bond, good flexibility of the molecular chain, and very low glass transition temperature.

[0004] However, in practical applications, liquid silicone is prone to bleeding problems in the hot pressing / injection molding process, which limits the application of liquid silicone in micro loudspeakers.

[0005] Therefore, it is necessary to provide a new diaphragm to solve the above problems.

Summary of the Invention

[0006] The technical problem to be solved by the present invention is to provide a diaphragm with higher low-temperature and high-temperature resistance.

[0007] To solve the above technical problem, in a first aspect, the present invention provides a diaphragm for a sound generating device to achieve vibration and sound generation, characterized in that the diaphragm is made of liquid silicone, and the liquid silicone comprises the following components by mass percentage: vinyl-containing polydimethylsiloxane 50%-90%, silicon hydride-containing organopolysiloxane 0.5%-10%, and catalyst 0.01%-5%.

[0008] Preferably, the molecular general formula of the vinyl-containing polydimethylsiloxane is , where m > 0, n ≥ 0, and m and n are both integers.

[0009] Preferably, the silicon hydride-containing organopolysiloxane contains at least three silicon-hydrogen bonds.

[0010] Preferably, the molecular general formula of the silicon hydride-containing organopolysiloxane is , where m > 0, n ≥ 0, and m and n are both integers.

[0011] Preferably, the catalyst is a platinum catalyst, and the platinum catalyst includes at least one of a platinum-vinylsiloxane complex, a thermoplastic resin or a hot-melt compound-embedded platinum-vinylsiloxane complex, an alcohol-modified chloroplatinic acid, and a platinum-alkynyl complex.

[0012] Preferably, the components of the liquid silicone rubber further include a reinforcing filler, and the mass percentage of the reinforcing filler is 1%-50%; the reinforcing filler includes at least one of fumed silica, precipitated silica, graphene, carbon nanotubes, montmorillonite, calcium carbonate, poly(silsesquioxane), boron carbide, magnesium hydroxide, and alumina.

[0013] Preferably, the components of the liquid silicone rubber further include an inhibitor, and the mass percentage of the inhibitor is 0.01%-5%; the inhibitor is an alkynyloxy silane, including at least one of 3-methyl-1-butyn-3-ol, 3-methyl-1-pentyn-3-ol, 3,5-dimethyl-1-hexyn-3-ol, and 1-ethynyl-1-cyclohexanol.

[0014] Preferably, the components of the liquid silicone rubber further include an auxiliary agent, and the mass percentage of the auxiliary agent is 0.1%-5%; the auxiliary agent is at least one of a fluidity regulator, an antifoaming agent, and a pigment.

[0015] In a second aspect, the present invention further provides a method for preparing a diaphragm as described above, and the preparation method includes the following steps:

[0016] The liquid silicone rubber is formed into a single-layer film through coating and tunnel drying treatment, wherein the hardness of the liquid silicone rubber is 20A-80A, the coating temperature is 80°C-130°C, the tunnel drying treatment time is 30s-300s, and the thickness of the single-layer film is 30μm-150μm;

[0017] The single-layer film is formed into the diaphragm by means of pneumatic forming.

[0018] Preferably, in the step of coating the liquid silicone rubber, it further includes:

[0019] Adding a diluent, and the diluent is toluene or ethyl acetate.

[0020] In a third aspect, the present invention further provides a micro speaker, and the micro speaker includes a vibration system and a magnetic circuit system for driving the vibration system to vibrate and generate sound, and the vibration system includes the diaphragm as described above.

[0021] Compared with the related art, the diaphragm provided by the present invention is used for a sounding device to realize vibration and sound production. It is characterized in that the diaphragm is made of liquid silicone rubber, and the liquid silicone rubber comprises the following components by mass percentage: vinyl-containing polydimethylsiloxane 50%-90%, silicon hydride-containing organopolysiloxane 0.5%-10%, catalyst 0.01%-5%. The diaphragm of the liquid silicone rubber has good low-temperature resistance and high-temperature resistance, and the modulus basically does not change within the temperature range of -60°C to 200°C. Moreover, the air pressure forming method solves the problem of glue overflow in the conventional hot pressing and injection molding processes of liquid silicone rubber, improves the production efficiency, the sensitivity of the micro speaker using this diaphragm at low temperature can be improved, and the product stability is enhanced.

Description of the Drawings

[0022] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained according to these drawings, where:

[0023] Figure 1 It is a schematic diagram of the comparison result of the temperature resistance test of the diaphragm prepared in the embodiment of the present invention and the comparative example;

[0024] Figure 2 It is a schematic diagram of the comparison result of the low-temperature and normal-temperature sensitivity tests of the diaphragm prepared in the embodiment of the present invention and the comparative example.

Specific Embodiments

[0025] The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.

[0026] The embodiment of the present invention provides a diaphragm for a sounding device to realize vibration and sound production. It is characterized in that the diaphragm is made of liquid silicone rubber, and the liquid silicone rubber comprises the following components by mass percentage: vinyl-containing polydimethylsiloxane 50%-90%, silicon hydride-containing organopolysiloxane 0.5%-10%, catalyst 0.01%-5%.

[0027] The bond energy of the silicon-oxygen bond (Si-O) in the main chain of liquid silicone is 451 kJ / mol, which is much higher than that of the carbon-carbon bond (C-C) in the main chain of ordinary polymer materials (345 kJ / mol). Higher energy is required to break its molecular structure. Therefore, liquid silicone has excellent heat resistance. The bond length of the silicon-oxygen bond in the main chain of liquid silicone (0.164 nm) is longer than that of the carbon-carbon bond (0.154 nm), with a large bond angle, capable of free rotation, and small intermolecular forces. Therefore, the molecular chain is flexible, and the glass transition temperature is very low. At extremely low temperatures, it can still maintain good elasticity because liquid silicone has excellent low-temperature resistance.

[0028] The molecular weight of vinyl polydimethylsiloxane ranges from several thousand to over one hundred thousand. The one with a small molecular weight has a low viscosity, which can increase the crosslinking degree of liquid silicone and improve the strength and hardness of liquid silicone; the one with a large molecular weight has a high viscosity, which can increase the elongation and elasticity of liquid silicone. In the actual application process, vinyl polydimethylsiloxanes with different molecular weights can be used in combination to improve the comprehensive performance of liquid silicone. The vinyl group can be located at the end of the polyorganosiloxane or on the side chain.

[0029] Preferably, the molecular general formula of the vinyl-containing polydimethylsiloxane is , where m > 0, n ≥ 0, and both m and n are integers.

[0030] The organopolysiloxane containing silicon hydride is a crosslinking agent for addition-curing liquid silicone, and the organopolysiloxane containing silicon hydride contains at least three silicon-hydrogen bonds (Si-H). When combined with vinyl polydimethylsiloxane, the molar amount of the silicon-hydrogen bond should be moderately more than that of the vinyl group, and the ratio of the two is about 1.2 - 2.0. The hydrogen content of the organopolysiloxane has a significant impact on the performance of liquid silicone. When a low hydrogen content is selected, the elongation of liquid silicone is relatively high; while when a high hydrogen content is used, liquid silicone has a higher hardness and a faster vulcanization rate.

[0031] Preferably, the molecular general formula of the organopolysiloxane containing silicon hydride is , where m > 0, n ≥ 0, and both m and n are integers.

[0032] The catalyst is used to catalyze the reaction between vinyl and silicon hydride. Considering factors such as comprehensive cost and activity, the catalyst is a platinum catalyst, and the platinum catalyst includes at least one of a platinum-vinylsiloxane complex, a thermoplastic resin or a hot-melt compound-embedded platinum-vinylsiloxane complex, an alcohol-modified chloroplatinic acid, and a platinum-alkynyl complex.

[0033] In other alternative embodiments, the components of the liquid silicone rubber further include a reinforcing filler, and the mass percentage of the reinforcing filler is 1%-50%; the reinforcing filler includes at least one of fumed silica, precipitated silica, graphene, carbon nanotubes, montmorillonite, calcium carbonate, poly(silsesquioxane), boron carbide, magnesium hydroxide, and alumina. It can be understood that when the mass content of the reinforcing filler in the liquid silicone rubber increases, the strength of the liquid silicone rubber also increases.

[0034] In other alternative embodiments, the components of the liquid silicone rubber further include an inhibitor, and the mass percentage of the inhibitor is 0.01%-5%; the inhibitor is an alkynylsilane, including at least one of 3-methyl-1-butyn-3-ol, 3-methyl-1-pentyn-3-ol, 3,5-dimethyl-1-hexyn-3-ol, and 1-ethynyl-1-cyclohexanol. The main function of the inhibitor is to reduce the activity of the catalyst, adjust the gel time, and extend the service life.

[0035] In other alternative embodiments, the components of the liquid silicone rubber further include an auxiliary agent, and the mass percentage of the auxiliary agent is 0.1%-5%; the auxiliary agent is at least one of a fluidity regulator, an antifoaming agent, and a pigment; the mass content of the auxiliary agent is 0.1%-5%. The leveling agent and the antifoaming agent can improve the appearance performance during the coating of the liquid silicone rubber, and the pigment can increase the appearance beauty of the prepared diaphragm.

[0036] The embodiment of the present invention also provides a method for preparing a diaphragm as described in the above embodiment, and the preparation method includes the following steps:

[0037] Form a single-layer film by coating and drying tunnel treatment of the liquid silicone rubber;

[0038] Form the single-layer film into the diaphragm by means of pneumatic forming.

[0039] Among them, the hardness of the liquid silicone rubber is 20A-80A. When the hardness is too low, the tensile strength of the single-layer film obtained by coating is too small and it is easily blown out during the pneumatic forming process and cannot be formed into a diaphragm.

[0040] The coating temperature is 80°C-130°C, and the drying tunnel treatment time is 30s-300s. If the coating temperature is too low and the drying tunnel time is too short, the single-layer film does not have a certain degree of crosslinking, the surface is not dry, and it cannot be wound; if the coating temperature is too high and the drying tunnel time is too long, the crosslinking degree of the single-layer film is too large and it is close to complete curing. During the next pneumatic forming, the forming size is not in place and a complete diaphragm pattern cannot be obtained.

[0041] The thickness of the single-layer film is 30um - 150um. The single-layer film needs to be within a certain thickness range. If the thickness is too thin, the tensile strength is small and the film is likely to break during pneumatic forming; if the thickness is too large, the tensile strength is too high, the size during pneumatic forming is not in place, and moreover, a too thick vibrating film will occupy the vibration space and affect the acoustic performance of the micro speaker.

[0042] Preferably, in the step of coating the liquid silicone, it further includes:

[0043] Adding a diluent, and the diluent is toluene or ethyl acetate.

[0044] Exemplarily, based on the method for preparing the vibrating film provided by the embodiments of the present invention, referring to the steps of the above embodiments, the present invention embodiments provide the following two available preparation processes and parameters:

[0045] Method 1: The vibrating film 10, with a thickness of 120um, is made by pneumatic forming of a single-layer film formed by coating liquid silicone. The hardness of the liquid silicone is 40A, the coating temperature is 100°C, and the drying tunnel time is 100s.

[0046] Method 2: The vibrating film 20, with a thickness of 80um, is made by pneumatic forming of a single-layer film formed by coating liquid silicone. The hardness of the liquid silicone is 70A, the coating temperature is 110°C, and the drying tunnel time is 80s.

[0047] Meanwhile, the present invention embodiments also provide the preparation process and parameters of the vibrating film 30 of the comparative example:

[0048] Comparative example: The vibrating film 30, with a thickness of 80um, is made by pneumatic forming of an 80um single-layer rubber film layer. The hardness of the rubber is 70A, the coating temperature is 130°C, and the drying tunnel time is 300s.

[0049] The test data of the vibrating films prepared by the above embodiments and comparative examples are shown in Table 1 below. Among them, the test methods for elongation at break and tensile strength are in accordance with the GB / T 528 - 2009 standard, the tensile rate is 500mm / min, the gauge length is 25mm, the temperature is 23 ± 2°C, and the humidity is 50 ± 10% RH; the test method for glass transition temperature is in accordance with the ASTM D882 standard, the heating rate is 3°C / min, the strain is 0.2%, the tensile mode, and the temperature corresponding to the peak value of the loss factor is selected as the glass transition temperature.

[0050] Table 1 Test data of the vibrating films prepared by the embodiments and comparative examples

[0051]

[0052]

[0053] The temperature resistance test results of the vibrating films prepared by the embodiments and comparative examples are as Figure 1As shown, the low-temperature and normal-temperature sensitivity test results are as Figure 2 shown.

[0054] It can be seen that the diaphragms 10 and 20 made of liquid silicone have better modulus stability than the diaphragm 30 made of rubber under the temperature resistance test, and have better low-temperature sensitivity; in the test of the glass transition temperature, the diaphragms 10 and 20 made of liquid silicone have a lower transition temperature than the diaphragm 30 made of rubber, and the single-layer film elongation at break is also lower.

[0055] The embodiment of the present invention also provides a micro speaker, which includes a vibration system and a magnetic circuit system for driving the vibration system to vibrate and generate sound. The vibration system includes the diaphragm as described in the above embodiment. It can be understood that the micro speaker provided by the embodiment of the present invention solves the problem of glue overflow during the molding of liquid silicone. Based on the application of the diaphragm made of liquid silicone, the performance of the micro speaker at low temperature is improved.

[0056] Compared with the related art, the diaphragm provided by the present invention is used for a sound generating device to realize vibration and sound generation. The diaphragm is made of liquid silicone, and the liquid silicone includes the following components by mass percentage: vinyl-containing polydimethylsiloxane 50%-90%, silicon hydride-containing organopolysiloxane 0.5%-10%, catalyst 0.01%-5%. The diaphragm made of liquid silicone has good low-temperature and high-temperature resistance, and the modulus basically does not change within the temperature range of -60°C to 200°C. And the air pressure molding method solves the problem of glue overflow in the conventional hot pressing and injection molding processes of liquid silicone, improves the production efficiency, and the sensitivity of the micro speaker using this diaphragm can be improved at low temperature, and the product stability is improved.

[0057] The above are only the embodiments of the present invention. It should be noted here that for those of ordinary skill in the art, without departing from the creative concept of the present invention, improvements can still be made, but these all belong to the protection scope of the present invention.

Claims

1. A diaphragm used in a sound-generating device to achieve vibration and sound generation, characterized in that: The diaphragm is made of liquid silicone, which comprises the following components by mass percentage: 50%-90% of vinyl-containing polydimethylsiloxane, 0.5%-10% of silicon-hydrogen-containing organic polysiloxane, and 0.01%-5% of a catalyst.

2. The diaphragm according to claim 1, characterized in that: The molecular formula of the vinyl-containing polydimethylsiloxane is , where m>0, n≥0, and m and n are both integers.

3. The diaphragm according to claim 1, characterized in that: The silicon-hydrogen-containing organopolysiloxane contains at least three silicon-hydrogen bonds.

4. The diaphragm according to claim 3, characterized in that: The molecular formula of the organopolysiloxane containing silicon hydrogen is Among them, m>0, n≥0, and m and n are both integers.

5. The diaphragm according to claim 1, characterized in that: The catalyst is a platinum catalyst, and the platinum catalyst includes at least one of a platinum-vinylsiloxane complex, a thermoplastic resin or a hot-melt compound embedded platinum-vinylsiloxane complex, an alcohol-modified chloroplatinic acid, and a platinum-alkyne-based complex.

6. The diaphragm according to claim 1, characterized in that: The components of the liquid silica gel also include reinforcing fillers, and the mass percentage of the reinforcing fillers is 1%-50%; the reinforcing fillers include at least one of fumed silica, precipitated silica, graphene, carbon nanotubes, montmorillonite, calcium carbonate, polysilsesquioxane, boron carbide, magnesium hydroxide, and aluminum oxide.

7. The diaphragm according to claim 1, characterized in that: The components of the liquid silica gel also include an inhibitor, and the mass percentage of the inhibitor is 0.01%-5%; the inhibitor is an alkynyloxysilane, including at least one of 3-methyl-1-butyn-3-ol, 3-methyl-1-pentyn-3-ol, 3.5-dimethyl-1-hexyn-3-ol, and 1-ethynyl-1-cyclohexanol.

8. The diaphragm according to claim 1, characterized in that: The components of the liquid silica gel also include an auxiliary agent, and the auxiliary agent is 0.1%-5% by mass; the auxiliary agent is at least one of a fluidity regulator, a defoaming agent, and a pigment.

9. A method for preparing a diaphragm according to any one of claims 1 to 8, characterized in that: The preparation method comprises the following steps: Forming a single-layer film by coating and drying liquid silicone, wherein the hardness of the liquid silicone is 20A-80A, the coating temperature is 80°C-130°C, the drying time is 30s-300s, and the thickness of the single-layer film is 30um-150um; The single-layer film is formed into the diaphragm by air pressure forming.

10. The method for preparing a diaphragm according to claim 9, characterized in that: The step of coating the liquid silicone further includes: A diluent is added, which is toluene or ethyl acetate.

11. A micro speaker, characterized in that: The micro-speaker comprises a vibration system and a magnetic circuit system for driving the vibration system to vibrate and produce sound, and the vibration system comprises the diaphragm as described in any one of claims 1-8.

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