Rubber diaphragm, and sound production device and use thereof

Abstract

A rubber diaphragm of the present invention contains 0.3%-60% by mass of a distortion improver, wherein the distortion improver is a high-molecular polymer with a hyperbranched structure and has 0.01%-15% by mass of special chemical crosslinking points, the branched chains of the high-molecular polymer with the hyperbranched structure are long-chain structures or short-chain structures prepared by means of living polymerization, each distortion improver molecule contains at least three long-chain structures or short-chain structures, the long-chain structures or short-chain structures have a number-average molecular weight of 200-50,000, the special chemical crosslinking points are distributed at the outermost end of the hyperbranched structure, and at least six carbon atoms are spaced between adjacent special chemical crosslinking points. The damping peak position, height and width of the rubber diaphragm of the present invention are controllable, thereby improving the mechanical properties, and ensuring that the rubber diaphragm has stable performance and excellent processability. The present invention further provides a sound production device and a use thereof.

Description

A rubber sound membrane, a sound-generating device and its application

Technical field

[0001] The present invention relates to the field of new materials, and in particular to a rubber sound membrane, a sound-generating device and applications thereof. [Background Technology]

[0002] Due to their unique physical properties, rubber diaphragms are gaining popularity in high-end sound-generating devices. Improving their performance and reducing the THD of sound-generating devices by applying distortion modifiers to them is gaining increasing attention. While small-molecule distortion modifiers significantly improve distortion, they also compromise some of the diaphragm's mechanical properties. High-molecular-weight distortion modifiers can improve distortion with minimal loss of mechanical properties, but they are generally linear polymers. Crosslinking points, due to segment shielding and steric hindrance, are difficult to fully and effectively react, resulting in unstable diaphragm performance.

[0003] Therefore, there is an urgent need in this field for a rubber sound membrane that can improve distortion, cause less loss in the mechanical properties of the rubber sound membrane, and at the same time ensure the stability of the performance of the rubber sound membrane.

[0004] [Summary of the invention]

[0005] In order to solve the above technical problems, the present invention provides a rubber sound membrane, which contains a distortion improver in an amount of 0.3% to 60% by mass. The distortion improver is a high molecular polymer with a hyperbranched structure, and the distortion improver has a special chemical cross-linking point in an amount of 0.01% to 15% by mass. The branched chains of the high molecular polymer with a hyperbranched structure are long chain structures or short chain structures, and each distortion improver molecule contains at least 3 long chain structures or short chain structures. The number average molecular weight of the long chain structure or short chain structure is 200 to 50,000. The long chain structure or short chain structure is prepared by active polymerization, and the special chemical cross-linking points are distributed at the outermost end of the hyperbranched structure, and adjacent special chemical cross-linking points are separated by at least 6 carbon atoms.

[0006] Preferably, the number average molecular weight of the high molecular weight polymer having a hyperbranched structure is 1,000 to 1,000,000.

[0007] Preferably, the living polymerization includes living free radical polymerization, anionic polymerization, cationic polymerization or coordination polymerization.

[0008] Preferably, the special chemical crosslinking points include at least one of a double bond, a triple bond, an isocyanate group, a silicon-hydrogen bond, a silicon-chloro bond, an azide group, an epoxy group, a nitrile group, a silicon-oxygen bond, a carboxyl group, a hydroxyl group, an amide group, an amino group, an acyl chloride bond, and an anhydride group.

[0009] Preferably, the rubber sound membrane further contains main rubber, reinforcing filler, vulcanizing agent, vulcanizing aid, antioxidant, release agent and plasticizer.

[0010] The rubber sound membrane provided by the present invention contains a special distortion improver. Specifically, the distortion improver is a high molecular polymer with a hyperbranched structure, and its branch is a long chain structure or a short chain structure prepared by active polymerization. Each distortion improver molecule contains at least 3 long chain structures or short chain structures. The special chemical cross-linking points are distributed at the outermost end of the hyperbranched structure, and the adjacent special chemical cross-linking points are separated by at least 6 carbon atoms. The active polymerization is used for preparation, so the branched structure is controllable, so the damping peak position, height, width and narrowness of the rubber sound membrane are also controllable. The special chemical cross-linking points are located at the outermost end of the hyperbranched structure, which can effectively avoid the incomplete effective reaction of the cross-linking points caused by molecular chain entanglement or steric hindrance effect, so that the cross-linking points can effectively and fully react, and at the same time play the role of concentrating the cross-linking points, which can greatly improve the mechanical properties of the rubber sound membrane and ensure the stability of the rubber sound membrane performance. In addition, the hyperbranched structure also makes the rubber sound membrane have excellent processing performance.

[0011] In another aspect, the present invention further provides a sound-generating device comprising the aforementioned rubber diaphragm. In a specific low-frequency band, the sound-generating device significantly reduces THD, improving sound quality while having little effect on F0 and frequency response. The sound-generating device can be used in mobile phones, headphones, smart watches, tablets, laptops, desktop computers, speakers, televisions, automobiles, and other fields.

Brief Description of the Drawings

[0012] FIG1 is a schematic diagram of the molecular structure of the distortion improving agent of the present invention;

[0013] FIG. 2 is a THD curve diagram of a speaker made using a conventional rubber diaphragm and a speaker made using the rubber diaphragm of the present invention. [Specific implementation method]

[0014] The present invention will be described below with reference to the accompanying drawings and embodiments.

[0015] Synthesis of 2-bromosuccinic acid dipropynyl ester (BPBS):

[0016] To a reactor, 100 parts by weight of 2-bromosuccinic acid, 290 parts by weight of propargyl alcohol, and 5 parts by weight of p-toluenesulfonic acid were added, followed by 1000 parts by weight of dry toluene. Once completely dissolved, the mixture was reacted in a 90°C oil bath for 36 hours. After completion of the reaction, the mixture was cooled to room temperature and the toluene was removed by rotary evaporation at 60°C under reduced pressure. The product was then redissolved in 1500-2000 parts of dichloromethane, washed four times with a 3% to 5% wt NaOH solution and four times with water, and dried over an excess of anhydrous MgSO₄. The filtrate was then filtered and collected. The dichloromethane was removed by rotary evaporation at 35°C under reduced pressure. The product was then passed through a 60 cm silica gel column (eluent: ethyl acetate:dichloromethane = 3:1). The product solution was then rotary evaporated at 50°C to remove the eluent and dried in a vacuum oven at room temperature for 48 hours to obtain dipropargyl 2-bromosuccinate (BPBS).

[0017] Synthesis of linear styrene (Br-PS):

[0018] By mass, 1 part BPBS, 2 parts bipyridine, 15 parts styrene, and 0.5 parts CuBr were added to the reactor in sequence. Nitrogen was passed through for 1 hour, followed by reaction at 110°C for 2 hours, followed by rapid cooling to room temperature and ventilation. Post-treatment: First, the polymer solution was diluted with THF and passed through a 30 cm neutral alumina column to remove copper. The resulting polymer solution was slowly added dropwise to methanol for precipitation, then placed in a refrigerator and frozen for 1 hour. After filtration, the solid product was dissolved in THF and precipitated again with methanol. Stirring was placed in a refrigerator and frozen for 1 hour. Finally, after filtration, the product was dried in a vacuum drying oven at room temperature for 48 hours to obtain linear styrene (Br-PS).

[0019] Example 1:

[0020] By mass, 100 parts of linear styrene (Br-PS), 30 parts of 2-ethylhexyl acrylate, 2 parts of bipyridine, and 0.5 parts of CuBr were taken. Nitrogen was passed through for 1 hour, then the reaction was carried out at 110°C for 2 hours, and then the mixture was rapidly cooled to room temperature and ventilated. Post-treatment: First, the polymer solution was diluted with THF and passed through a 30cm neutral alumina column to remove copper. The resulting polymer solution was slowly added dropwise to methanol for precipitation, and then placed in a refrigerator and frozen for 1 hour. After filtration, a solid product was obtained, which was dissolved in THF and precipitated again with methanol. Stirred and placed in a refrigerator to cool for 1 hour. Finally, after filtration, the solution was dried in a vacuum drying oven at room temperature for 48 hours to obtain Br-PS-P2HEA (a copolymer of bromine-containing styrene and 2-ethylhexyl acrylate).

[0021] 1 part Br-PS-P2HEA and 0.3 part sodium azide were added to 3 parts dry N,N-dimethylformamide (DMF) by mass. After magnetic stirring to fully dissolve, the mixture was reacted at 40°C for 24 hours. After the reaction, the polymer solution was diluted with THF and then passed through a 30 cm neutral alumina column to remove the metal salt (sodium azide). The solution was then precipitated in methanol, dissolved again, and dried in a vacuum oven at room temperature for 48 hours to obtain N3-PS-P2HEA (a copolymer of styrene and 2-ethylhexyl acrylate containing an azide group).

[0022] Dissolve 1 part N3-PS-P2HEA, 1 part CuBr, and 1 part pentamethyldiethylenetriamine (PMDETA) in an appropriate amount of dry DMF by weight under magnetic stirring until completely dissolved. Purge with nitrogen for 1 hour, then react at 60°C for 24 hours. Cool to room temperature and purge with air. Post-treatment: First, dilute the polymer solution with THF and pass it through a 30 cm neutral alumina column to remove copper. Then, precipitate the polymer solution in methanol, filter, and repeat the precipitation twice. Dry in a vacuum oven at room temperature for 48 hours to obtain the desired distortion improver 1.

[0023] Taking hydrogenated nitrile rubber (HNBR) as an example, a rubber compound containing distortion improver 1 was prepared according to Table 1. The compound was then pressed or coated into a thin sheet of approximately 100 microns using a rubber calender, flatbed vulcanizer, or coater. A diaphragm press was used to hot-press the rubber diaphragm at 200°C and 0.2 MPa for 10 minutes. The diaphragm was then assembled into a speaker and its distortion (THD) performance was tested. The results are shown in Figure 2.

[0024] Example 2:

[0025] By mass, 100 parts of linear styrene (Br-PS), 35 parts of 2-ethylhexyl acrylate, 2 parts of bipyridine, and 0.5 parts of CuBr were added. Nitrogen was passed through for 1 hour, followed by reaction at 110°C for 2 hours. The mixture was then rapidly cooled to room temperature and ventilated. Post-treatment: The polymer solution was first diluted with THF and passed through a 30cm neutral alumina column to remove copper. The resulting polymer solution was slowly added dropwise to methanol for precipitation, then placed in a refrigerator and chilled for 1 hour. After filtration, the solid product was dissolved in THF and precipitated again with methanol. Stirred and placed in a refrigerator for 1 hour. Finally, after filtration, the product was dried in a vacuum oven at room temperature for 48 hours to obtain Br-PS-P2HEA.

[0026] To prepare 1 part Br-PS-P2HEA and 0.3 parts sodium azide by weight, add 3 parts dry N,N-dimethylformamide (DMF). After magnetic stirring to fully dissolve, react at 40°C for 24 hours. After the reaction, dilute the polymer solution with THF and pass it through a 30cm neutral alumina column to remove the metal salt (sodium azide). The solution is then precipitated in methanol, dissolved again, and dried in a vacuum oven at room temperature for 48 hours to obtain N3-PS-P2HEA.

[0027] Dissolve 1 part N3-PS-P2HEA, 1 part CuBr, and 1 part pentamethyldiethylenetriamine (PMDETA) in an appropriate amount of dry DMF by weight under magnetic stirring until completely dissolved. Purge with nitrogen for 1 hour, then react at 60°C for 24 hours. Cool to room temperature and purge with air. Post-treatment: First, dilute the polymer solution with THF and pass it through a 30 cm neutral alumina column to remove copper. Then, precipitate the polymer solution in methanol, filter, and repeat the precipitation twice. Dry in a vacuum oven at room temperature for 48 hours to obtain the desired distortion improver 2.

[0028] Taking hydrogenated nitrile rubber (HNBR) as an example, a rubber compound containing distortion improver 2 was prepared according to Table 1. The compound was then pressed or coated into a thin sheet of approximately 100 microns using a rubber calender, flatbed vulcanizer, or coater. A diaphragm press was used to hot-press the rubber diaphragm at 200°C and 0.2 MPa for 10 minutes. The diaphragm was then assembled into a speaker and its distortion (THD) performance was tested. The results are shown in Figure 2.

[0029] Example 3:

[0030] By mass, take 100 parts of linear styrene (Br-PS), 50 parts of n-butyl acrylate, 2 parts of bipyridine, and 0.5 parts of CuBr. Flow nitrogen for 1 hour, then react at 110°C for 2 hours, then quickly cool to room temperature and ventilate. Post-treatment: First, dilute the polymer solution with THF and pass it through a 30cm neutral alumina column to remove copper. The resulting polymer solution is slowly added dropwise to methanol for precipitation, and then placed in a refrigerator and frozen for 1 hour. After filtration, a solid product is obtained, which is dissolved in THF and precipitated again with methanol. Stir and place in a refrigerator to cool for 1 hour. Finally, after filtration, it is dried in a vacuum drying oven at room temperature for 48 hours to obtain Br-PS-PBA (a copolymer of styrene and n-butyl acrylate containing bromine groups).

[0031] 1 part Br-PS-PBA and 0.3 parts sodium azide were added to 3 parts dry N,N-dimethylformamide (DMF) by weight. After magnetic stirring to fully dissolve, the mixture was reacted at 40°C for 24 hours. After the reaction, the polymer solution was diluted with THF and then passed through a 30 cm neutral alumina column to remove the metal salt (sodium azide). The solution was then precipitated in methanol, dissolved again, and dried in a vacuum oven at room temperature for 48 hours to obtain N3-PS-PBA (a copolymer of styrene and n-butyl acrylate containing an azide group).

[0032] Dissolve 1 part N3-PS-PBA, 1 part CuBr, and 1 part pentamethyldiethylenetriamine (PMDETA) in an appropriate amount of dry DMF by weight under magnetic stirring until completely dissolved. Purge with nitrogen for 1 hour, then react at 60°C for 24 hours. Cool to room temperature and purge with air. Post-processing: First, dilute the polymer solution with THF and pass it through a 30 cm neutral alumina column to remove copper. Then, precipitate the polymer solution in methanol, filter, and repeat the precipitation twice. Dry in a vacuum oven at room temperature for 48 hours to obtain the desired distortion improver 3.

[0033] Taking hydrogenated nitrile rubber (HNBR) as an example, a rubber compound containing distortion improver 3 was prepared according to Table 1. The compound was then pressed or coated into a thin sheet of approximately 100 microns using a rubber calender, flatbed vulcanizer, or coater. A diaphragm press was then used to hot-press the rubber diaphragm at 200°C and 0.2 MPa for 10 minutes. The diaphragm was then assembled into a speaker and its distortion (THD) performance was tested. The results are shown in Figure 2.

[0034] In a specific low-frequency band, the THD of the sound-generating device is significantly reduced, the sound quality is improved, and at the same time, F0 and frequency response are almost unaffected. The sound-generating device can be applied to mobile phones, headphones, smart watches, tablet computers, laptops, desktop computers, speakers, televisions, automobiles and other fields.

[0035] The sound-generating device including the rubber sound membrane of the present invention may be, but is not limited to, a loudspeaker, a receiver, and other sound-generating devices. The loudspeaker is used as an example for illustration, but is not intended to limit the scope of application of the present invention.

[0036] Table 1 (Unit: parts (by mass))

[0037] While some specific embodiments of the present invention have been described in detail above, those skilled in the art will appreciate that the above embodiments are for illustrative purposes only and are not intended to limit the scope of the present invention. Those skilled in the art will appreciate that any modifications, equivalent substitutions, and improvements to the above embodiments, without departing from the spirit and principles of the present invention, are intended to be within the scope of protection of the present invention.

Claims

1. A rubber sound film, characterized in that, the rubber sound film contains a distortion improver with a mass percentage of 0.3% to 60%, the distortion improver is a hyperbranched polymer, the distortion improver has special chemical crosslinking points with a mass percentage of 0.01% to 15%, the branches of the hyperbranched polymer are long-chain structures or short-chain structures, each distortion improver molecule contains at least 3 of the long-chain structures or short-chain structures, the number-average molecular weight of the long-chain structure or short-chain structure is 200 to 50,000, the long-chain structure or short-chain structure is prepared by living polymerization, the special chemical crosslinking points are distributed at the outermost end of the hyperbranched structure, and there are at least 6 carbon atoms between adjacent special chemical crosslinking points.

2. The rubber sound film according to claim 1, characterized in that, the number-average molecular weight of the hyperbranched polymer is 1,000 to 1,000,000.

3. The rubber sound film according to claim 1, characterized in that, the living polymerization includes living radical polymerization, anionic polymerization, cationic polymerization or coordination polymerization.

4. The rubber sound film according to claim 1, characterized in that, the special chemical crosslinking points include at least one of double bond, triple bond, isocyanate group, silicon-hydrogen bond, silicon-chlorine bond, azide group, epoxy group, nitrile group, silicon-oxygen bond, carboxyl group, hydroxyl group, amide group, amino group, acyl chloride bond, acid anhydride group.

5. The rubber sound film according to claim 1, characterized in that, the rubber sound film further contains matrix rubber, reinforcing filler, vulcanizing agent, vulcanization accelerator, antioxidant, mold release agent and plasticizer.

6. A sounding device, characterized in that, the sounding device includes the rubber sound film according to any one of claims 1 to 5.

7. A product applying the sounding device according to claim 6, characterized in that, the product includes one of a mobile phone, earphone, smart watch, tablet computer, notebook computer, desktop computer, speaker, television, automobile.

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