Diaphragm of a sound generating device and the sound generating device

Abstract

The present application discloses a diaphragm and a sound generating device of a sound generating device. The diaphragm includes at least one modified butyl rubber film layer, and the modified butyl rubber film layer is prepared by cross-linking reaction after mixing an inorganic hollow microsphere, an additive, and a polymer of isobutene and isoprene to form a mixed rubber. Among them, the diameter of the inorganic hollow microsphere is 10 μm to 100 μm, the distribution density of the inorganic hollow microsphere in the modified butyl rubber film layer is 0.15 g / cm<supgt;3< / supgt; to 0.9 g / cm<supgt;3< / supgt>, the compressive strength of the inorganic hollow microsphere is ≥50 MPa, and the percentage change in elastic modulus of the modified butyl rubber film layer under the conditions of a temperature of 90 °C and a humidity of 60% is ≤9.6%. By adding inorganic hollow microspheres to butyl rubber in the present application, the density of the diaphragm can be effectively reduced, the vibration mass of the vibration system is reduced, and the stability of the resonance frequency of the diaphragm is improved.

Description

Technical Field

[0001] The present application relates to the field of electroacoustic technology, and more specifically, to a diaphragm of a sound-generating device and a sound-generating device using the diaphragm. Background Art

[0002] In order to obtain a diaphragm with high sound quality, low mass and good waterproofness, the existing technology often changes the diaphragm material to meet the relevant requirements. The diaphragm made of rubber material has good waterproofness and can meet the demand for high sound quality, so it has begun to be used in the diaphragm field. However, the density of rubber material is relatively large. Compared with diaphragms of the same diameter made of other materials, the large mass of the diaphragm made of rubber material will lead to poor stability of the resonant frequency. In addition, the diaphragm of the existing technology is easy to deform in a high temperature and high humidity environment, which has a great impact on the diaphragm, thereby affecting the sound effect of the sound-generating device in a high temperature and high humidity environment.

[0003] Therefore, a new technical solution is needed to solve the above problems. Summary of the invention

[0004] One object of the present application is to provide a diaphragm for a sound-generating device.

[0005] Another object of the present application is to provide a sound-generating device composed of the above-mentioned diaphragm.

[0006] In order to achieve the above objectives, this application provides the following technical solutions.

[0007] According to the diaphragm of the sound-generating device of the first embodiment of the present application, the diaphragm includes at least one modified butyl rubber membrane layer, and the modified butyl rubber membrane layer is prepared by mixing inorganic hollow microspheres, additives, and a polymer of isobutylene and isoprene to form a mixed rubber and then cross-linking the mixed rubber, wherein the diameter of the inorganic hollow microspheres is 10 μm to 100 μm, and the distribution density of the inorganic hollow microspheres in the modified butyl rubber membrane layer is 0.15 g / cm 3 ~0.9g / cm 3 The compressive strength of the inorganic hollow microspheres is ≥50 MPa, and the elastic modulus change percentage of the modified butyl rubber film layer under the conditions of a temperature of 90° C. and a humidity of 60% is ≤9.6%.

[0008] According to some embodiments of the present application, the content of the inorganic hollow microspheres accounts for 5wt% to 55wt% of the total amount of the mixed rubber.

[0009] According to some embodiments of the present application, after the modified butyl rubber film layer is aged in hot air at 150° C. for 16 hours, the tensile strength of the modified butyl rubber film layer decreases by ≤51%, and the elongation at break decreases by ≤72%.

[0010] According to some embodiments of the present application, the mass change rate of the modified butyl rubber film layer after being immersed in a polar solvent for 50 hours is ≤23%.

[0011] According to some embodiments of the present application, the strain recovery ratio of the modified butyl rubber film layer after being at 23° C., having a strain of 10% and a relaxation time of 5 minutes is ≥69%.

[0012] According to some embodiments of the present application, the density of the modified butyl rubber film layer is 0.5 g / cm 3 ~1.1g / cm 3 .

[0013] According to some embodiments of the present application, the additives include a cross-linking agent, a reinforcing agent and an antioxidant, wherein the cross-linking agent is at least one of metal oxides, metal peroxides, sulfur, dithiocarbamate metal salts and thiourea vulcanization systems; the reinforcing agent is at least one of carbon black, white carbon black, calcium carbonate and nano titanium dioxide; the antioxidant is at least one of antioxidant N-445, antioxidant 246 and antioxidant 4010.

[0014] According to some embodiments of the present application, the content of the cross-linking agent accounts for 0.5wt% to 5.5wt% of the rubber mixture, the content of the reinforcing agent accounts for 5wt% to 72wt% of the rubber mixture, and the content of the antioxidant accounts for 0.1wt% to 6.2wt% of the rubber mixture.

[0015] According to some embodiments of the present application, the loss factor of the modified butyl rubber film layer at room temperature is greater than 0.11.

[0016] According to some embodiments of the present application, the glass transition temperature of the modified butyl rubber film layer is ≤-10°C.

[0017] According to some embodiments of the present application, the diaphragm is a single-layer structure, and the diaphragm is composed of a layer of the modified butyl rubber membrane layer.

[0018] According to some embodiments of the present application, the diaphragm is a composite layer structure, and the diaphragm also includes a membrane layer made of at least one of a thermoplastic elastomer, an engineering plastic, and a thermosetting elastomer.

[0019] According to the second aspect of the embodiment of the present application, the sound-emitting device 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 produce sound, and the diaphragm is the diaphragm according to the above-mentioned embodiment of the present application.

[0020] According to the third aspect of the present application, the sound-emitting device 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 according to the above-mentioned embodiment of the present application.

[0021] According to the diaphragm of the sound-generating device of the embodiment of the present application, after the inorganic hollow microspheres, additives and polymers of isobutylene and isoprene are mixed to form a mixed rubber, a cross-linking reaction is performed to prepare a modified butyl rubber membrane layer, and this is used as the diaphragm material, thereby reducing the density of the diaphragm and improving the sound sensitivity of the diaphragm. In addition, the above-mentioned diaphragm material can also improve the damping performance of the modified butyl rubber membrane layer, and at the same time, the modified butyl rubber membrane layer with inorganic hollow microspheres added has a reduced percentage change in elastic modulus under high temperature environment, which can reduce the swing vibration of the diaphragm, make the resonance frequency of the diaphragm more stable, and improve the sound effect of the sound-generating device in extreme environments.

[0022] 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

[0023] 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.

[0024] Figure 1 The intermediate frequency Fr (frequency response) curve of the modified butyl rubber membrane layer with different densities of the diaphragm of the sound-generating device according to the embodiment of the present application;

[0025] Figure 2 is a test curve of vibration displacement of different parts of the diaphragm of the sound-generating device according to an embodiment of the present application at different frequencies;

[0026] Figure 3 is a schematic diagram of the overall structure of a sound-generating device according to an embodiment of the present application;

[0027] Figure 4 is a schematic diagram of a partial structure of a sound-generating device according to an embodiment of the present application;

[0028] Figure 5 is a cross-sectional view of a sound-generating device according to an embodiment of the present application;

[0029] Figure 6 It is an exploded diagram of a sound-generating device according to an embodiment of the present application.

[0030] Reference numerals

[0031] Sound generating device 100;

[0032] Housing 10; voice coil 11; first diaphragm 12; second diaphragm 13; magnetic circuit system 14;

[0033] Diaphragm 15 ; folding ring portion 151 ; dome portion 152 . DETAILED DESCRIPTION

[0034] 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 arrangement of components and steps, numerical expressions and numerical values ​​set forth in these embodiments do not limit the scope of the present application.

[0035] The following description of at least one exemplary embodiment is merely illustrative in nature and is in no way intended to limit the present application, its application, or uses.

[0036] 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.

[0037] In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limiting. Therefore, other examples of the exemplary embodiments may have different values.

[0038] 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.

[0039] The diaphragm of the sound-generating device according to the embodiment of the present application is described in detail below with reference to the accompanying drawings.

[0040] The diaphragm of the sound-generating device according to the embodiment of the present application includes at least one modified butyl rubber membrane layer, which is prepared by mixing inorganic hollow microspheres, additives, and a polymer of isobutylene and isoprene to form a mixed rubber and then cross-linking the mixed rubber, wherein the diameter of the inorganic hollow microspheres is 10 μm to 100 μm, and the distribution density of the inorganic hollow microspheres in the modified butyl rubber membrane layer is 0.15 g / cm 3 ~0.9g / cm 3 The compressive strength of the inorganic hollow microspheres is ≥50MPa, and the elastic modulus change percentage of the modified butyl rubber membrane layer under the conditions of temperature 90°C and humidity 60% is ≤9.6%.

[0041] The diaphragm of the sound-emitting device according to the embodiment of the present application is composed of at least one layer of modified butyl rubber membrane layer. Specifically, the diaphragm in the present application can be a single-layer structure or a multi-layer composite structure. When the diaphragm is a single-layer structure, the diaphragm is made of a layer of modified butyl rubber membrane layer of the present application. When the diaphragm is a multi-layer composite structure, the diaphragm includes at least one layer of modified butyl rubber membrane layer, and the diaphragm is a composite of modified butyl rubber membrane layer and membrane layer of other materials. Optionally, when the diaphragm contains multiple layers of modified butyl rubber membrane layers, two adjacent layers of modified butyl rubber membrane layers can be spaced apart, and membrane layers of other materials can be arranged between two adjacent layers of modified butyl rubber membrane layers. In addition, two adjacent layers of modified butyl rubber membrane layers can also be arranged in a close fit. The specific setting method can be selected according to the actual use requirements, and the present application does not impose specific restrictions on this.

[0042] The polymer of isobutylene and isoprene in the present application refers to a polymer obtained by polymerization of small molecule isobutylene and small molecule isoprene, and the chemical formula of the polymer may be at least one of the following chemical formulas (I) and (II):

[0043]

[0044] In formula (I) and formula (II), m and n are natural numbers, and R is a methyl group or a halogenated group.

[0045] The modified butyl rubber membrane layer is made by adding inorganic hollow microspheres to a polymer of isobutylene and isoprene. Specifically, a rubber mix can be formed by kneading the inorganic hollow microspheres, additives, and a polymer of isobutylene and isoprene. The modified butyl rubber membrane layer can be formed after the rubber mix is ​​vulcanized. In other words, the polymer of isobutylene and isoprene can form butyl rubber, and butyl rubber is equivalent to the base material of the diaphragm material. After the inorganic hollow microspheres are kneaded with the polymer of isobutylene and isoprene, the inorganic hollow microspheres can be evenly dispersed in the base material. Since the density of the inorganic hollow microspheres is less than that of the rubber, by adding the inorganic hollow microspheres to the rubber, the density of the diaphragm material can be reduced, a low-density diaphragm can be obtained, and the vibration mass of the system can be reduced, thereby improving the sound sensitivity of the diaphragm.

[0046] The diameter of the inorganic hollow microbeads is 10μm to 100μm, and the preferred diameter is 15μm to 70μm. The diameter of the inorganic hollow microbeads can affect the mechanical properties of the diaphragm material. Specifically, the larger the diameter of the inorganic hollow microbeads, the smaller the density of the diaphragm can be, but the mechanical properties of the diaphragm material will gradually decrease. The smaller the diameter of the inorganic hollow microbeads, the larger the specific surface area, and the better the compatibility with butyl rubber, so that the inorganic hollow microbeads can be evenly dispersed in the rubber, but the inorganic hollow microbeads do not significantly reduce the density of the diaphragm. When the diameter of the inorganic hollow microbeads is 15μm to 70μm, not only can the density of the diaphragm be effectively reduced while ensuring the mechanical performance requirements of the diaphragm, but the inorganic hollow microbeads can also be evenly dispersed in the diaphragm material. Alternatively, the diameter of the inorganic hollow microspheres may be 10 μm, 15 μm, 20 μm, 25 μm, 30 μm, 35 μm, 40 μm, 45 μm, 50 μm, 55 μm, 60 μm, 65 μm, 70 μm, 75 μm, 80 μm, 85 μm, 90 μm, 95 μm or 100 μm.

[0047] The distribution density of inorganic hollow microspheres is 0.15g / cm 3 ~0.9g / cm 3 For example, the distribution density of inorganic hollow microspheres can be 0.15 g / cm 3 , 0.25g / cm 3 , 0.5g / cm 3 , 0.6g / cm 3 , 0.7g / cm 3 , 0.8g / cm 3 or 0.9g / cm 3 To ensure that the inorganic hollow microspheres can effectively reduce the diaphragm density, the preferred density is 0.25 g / cm 3 ~0.8g / cm 3 .

[0048] The compressive strength of inorganic hollow microspheres is ≥50MPa, that is, the inorganic hollow microspheres have a high compressive strength, which can not only ensure that the inorganic hollow microspheres are not squeezed and crushed during the mixing process, but also add them to butyl rubber to effectively improve the tensile strength of the modified butyl rubber film layer. When the diaphragm has a high mechanical strength, it can ensure that the diaphragm will not be over-stretched due to excessive driving force in extreme environments, further ensuring the use effect of the diaphragm.

[0049] By adding inorganic hollow microspheres to the modified butyl rubber film layer, the elastic modulus change percentage of the modified butyl rubber film layer under the conditions of temperature 90°C and humidity 60% is ≤9.6%, and the preferred elastic modulus change percentage is ≤8.4%. In other words, due to the high strength of inorganic hollow microspheres, the content of reinforcing agent in the rubber with inorganic hollow microspheres added is less than that of ordinary rubber at the same hardness of the diaphragm, thereby increasing the rubber content of the rubber with inorganic hollow microspheres added, and increasing the work required to overcome internal friction, thereby improving the damping performance of the modified butyl rubber. At the same time, the elastic modulus change percentage of the rubber with inorganic hollow microspheres added is small under high temperature environment, which reduces the number of swing vibrations of the diaphragm, and ultimately ensures the stability of the resonance frequency of the diaphragm.

[0050] It should be noted that the inorganic hollow microspheres can be hollow glass microspheres, hollow ceramic microspheres, etc. Among them, the hollow glass microspheres are mainly composed of inorganic materials such as silicon dioxide, aluminum oxide, zirconium oxide, magnesium oxide and sodium silicate compounds and inert gases enclosed inside. The main component of the hollow glass microsphere shell is borosilicate, which has the characteristics of high rigidity, good chemical stability and high melting point. After filling with rubber, it can effectively prevent rubber aging caused by light and heat, thereby improving the temperature resistance of the rubber material, and ensuring that the sound-generating device still has a good sounding effect in a high temperature environment. In addition, the inorganic hollow microspheres are very excellent thermal insulation materials, which can effectively block external heat and effectively slow down the damage of external heat to the internal network structure of the rubber.

[0051] Table 1 shows the change in modulus of butyl rubber with different contents of hollow glass microspheres added under high temperature and high humidity conditions.

[0052] First, the mixed rubber was vulcanized with a flat vulcanizer to obtain a vulcanized rubber sheet of 100mm×60mm×0.3mm. The vulcanization conditions were: temperature 155℃, time 15min, and pressure 12MPa. Then, ten identical vulcanized rubber sheets were prepared, with five in each group, divided into two groups, one for baking and the other for unbaked. Subsequently, the vulcanized rubber sheets in the baking group were placed in an oven for high temperature and high humidity testing. The high temperature and high humidity test conditions were: temperature 90℃, humidity 60%, and test time 16h.

[0053] After the test, the two groups of films were subjected to tensile performance tests. The tensile performance test conditions were as follows: testing was performed in accordance with the ASTM D412-2016 test standard, five samples were tested for each group of data, the average value was taken, and the percentage change of the modulus after baking relative to the modulus before baking was analyzed.

[0054] The influence of the content of inorganic hollow microspheres in the diaphragm material on the elastic modulus of the diaphragm material is shown in Table 1 below.

[0055] Table 1

[0056] Hollow glass microsphere addition amount (wt%) 0 5 10 30 40 50 Elastic modulus change percentage (%) 10.4 9.6 9.1 8.2 7.3 6.8

[0057] As shown in Table 1, as the content of hollow glass microspheres increases, the percentage change of the elastic modulus of the modified butyl rubber film layer gradually decreases. Specifically, when the content of hollow glass microspheres is 0, the percentage change of the elastic modulus of the modified butyl rubber film layer is 10.4%. When the content of hollow glass microspheres is 50wt%, the percentage change of the elastic modulus of the modified butyl rubber film layer is 6.8%.

[0058] In addition, since the content of reinforcing agent in the rubber added with inorganic hollow microspheres is less than that in ordinary rubber, the rubber content of the rubber added with inorganic hollow microspheres is increased, and the work required to overcome internal friction is increased, thereby improving the damping performance of the modified butyl rubber. At the same time, the change value of the elastic modulus of the rubber added with inorganic hollow microspheres becomes smaller in a high temperature environment, which reduces the number of swing vibrations of the diaphragm and makes the resonant frequency of the diaphragm more stable. That is, by adding inorganic hollow microspheres to the butyl rubber, the elastic modulus change percentage of the modified butyl rubber membrane layer is ≤9.6% under the conditions of temperature 90°C and humidity 60%.

[0059] Therefore, according to the diaphragm of the sound-generating device of the embodiment of the present application, the mixed rubber formed by mixing inorganic hollow microspheres, additives and polymers of isobutylene and isoprene is cross-linked to form a modified butyl rubber membrane layer, and this is used as the diaphragm material, which can reduce the density of the diaphragm and improve the sound sensitivity of the diaphragm. Moreover, the above-mentioned diaphragm material can also improve the damping performance of the modified butyl rubber membrane layer, and at the same time, the percentage change of the elastic modulus of the modified butyl rubber membrane layer with the addition of inorganic hollow microspheres in a high temperature environment is reduced, which can reduce the number of swing vibrations of the diaphragm and make the resonance frequency of the diaphragm more stable, thereby improving the sound effect of the sound-generating device in extreme environments.

[0060] In some specific embodiments of the present application, the content of the inorganic hollow microspheres accounts for 5wt% to 55wt% of the total amount of the mixed rubber.

[0061] That is to say, inorganic hollow microspheres accounting for 5wt% to 55wt% of the total amount of the mixed rubber can be added to the polymer of isobutylene and isoprene, preferably 10wt% to 40wt%. As the amount of inorganic hollow microspheres added increases, the density of the modified butyl rubber film layer decreases. In other words, the distribution density of inorganic hollow microspheres can be changed by controlling the addition of inorganic hollow microspheres, thereby obtaining a diaphragm material with desired performance. The content of inorganic hollow microspheres can be any value between 5wt% and 55wt%, including endpoint values. For example, the content of inorganic hollow microspheres can be 5wt%, 10wt%, 15wt%, 20wt%, 30wt%, 40wt%, 50wt% or 55wt%, etc.

[0062] The relationship between the mass proportion of inorganic hollow microspheres and the rubber density is shown in Table 2 below.

[0063] The rubber density is measured by a density balance. Three samples are tested for each set of values, and the average value of the three samples is taken. The inorganic hollow microspheres here are hollow glass microspheres.

[0064] Table 2

[0065] Hollow glass microsphere addition amount (wt%) 0 5 10 20 40 50 <![CDATA[Rubber density (g / cm 3 )]]> 1.26 1.21 1.08 0.78 0.59 0.56

[0066] As shown in Table 2, as the content of hollow glass microspheres increases, the density of rubber gradually decreases. It should be noted that since the density of hollow glass microspheres is much smaller than that of rubber, the density of rubber material will decrease significantly as the added mass of hollow glass microspheres increases.

[0067] Specifically, when the content of hollow glass microspheres is low (less than 5wt%), it has little effect on the density of the diaphragm material, and the diaphragm still has a relatively high density. When the content of hollow glass microspheres is too high (greater than 55wt%), due to its excessive mechanical strength, the maximum amplitude that can be achieved by the prepared diaphragm under the same driving force is reduced, so that the low frequency Fr of the sound-generating device is reduced. In addition, excessive addition of hollow glass microspheres will greatly reduce the density of the modified butyl rubber membrane layer, and the prepared diaphragm has low elongation at break and strength, which is prone to reliability problems such as collapse and film breakage.

[0068] It can be seen that by using the modified butyl rubber membrane layer prepared by adding 5wt% to 55wt% of inorganic hollow microbeads to the total amount of the mixed rubber as the diaphragm material, the density and strength of the diaphragm can be achieved at the same time, effectively ensuring the excellent mid-frequency and low-frequency performance of the diaphragm.

[0069] According to one embodiment of the present application, after the modified butyl rubber film layer is aged in hot air at 150° C. for 16 hours, the tensile strength of the modified butyl rubber film layer decreases by ≤51%, and the elongation at break decreases by ≤72%.

[0070] In other words, by adding inorganic hollow microspheres, the modulus of the rubber diaphragm can be greatly increased after the rubber is baked. Inorganic hollow microspheres have good high temperature resistance, will not decompose under high temperature conditions, and will maintain high strength, thus effectively improving the aging resistance of butyl rubber.

[0071] Specifically, the chemical composition of inorganic hollow microspheres is borosilicate, which has high temperature resistance. When added to butyl rubber, it forms a dense protective layer on the rubber surface, which can hinder the penetration of oxygen molecules and effectively improve the aging resistance of the rubber.

[0072] The effect of the content of inorganic hollow microspheres in the diaphragm material on the decrease rate of tensile strength and elongation at break of the diaphragm is shown in Table 3 below.

[0073] After butyl rubber added with hollow glass microspheres of different mass percentages was baked at 150°C for 16 hours, the decrease percentage of tensile strength and elongation at break was measured.

[0074] First, the mixed rubber was vulcanized with a flat vulcanizer to obtain a vulcanized film of 100mm×100mm×2mm. The vulcanization conditions were as follows: temperature 155°C, time 15min, and pressure 12MPa. Subsequently, the obtained film was subjected to tensile and tear tests, and the tensile strength was prepared into dumbbell-shaped samples according to the ASTM D412-2016 test standard. Five samples were tested for each set of data, and the average value was taken. The tear strength was prepared into a rectangular sample according to the ASTM D624-00 (2020) test standard, and five samples were tested for each set of data, and the average value was taken.

[0075] Table 3 shows the effect of different contents of hollow glass microspheres on the decrease rate of tensile strength and elongation at break of the modified rubber film layer under the condition of aging in air at 150°C for 16h.

[0076] Table 3

[0077]

[0078] As shown in Table 3, for the diaphragm material without hollow glass microspheres, after aging, the percentage of its tensile strength decrease is defined as Δ 1 For the diaphragm material with hollow glass microspheres added, the percentage of its tensile strength decrease after aging is defined as Δ 2 . Δ 1＞ Δ 2 The percentage decrease in the elongation at break of the first diaphragm material (the addition amount of the hollow glass microspheres is 0) is greater than the percentage decrease in the elongation at break of the second diaphragm material (a certain amount of the hollow glass microspheres is added).

[0079] That is to say, as the amount of inorganic hollow microspheres added increases, the percentage of decrease in tensile strength and elongation at break of the diaphragm material gradually decreases after aging, and the anti-aging performance of the diaphragm material is improved. That is, in extreme environments, the diaphragm material of the present application can still have good physical and chemical properties.

[0080] In some specific embodiments of the present application, the mass change rate of the modified butyl rubber membrane layer after being immersed in a polar solvent for 50 hours is ≤23%. That is to say, since the inorganic hollow microspheres are inorganic materials, they have excellent chemical stability. With the addition of inorganic hollow microspheres, the effective contact area between the diaphragm and the solvent is reduced, so that the mass change rate of the diaphragm immersed in polar solvents such as petroleum ether, ethanol, and ethyl acetate can be reduced.

[0081] The influence of the content of inorganic hollow microbeads in the diaphragm material on the mass change rate and volume change rate of the modified butyl rubber membrane layer is shown in Table 4 below.

[0082] During the measurement, the modified butyl rubber film layer was immersed in ethyl acetate solution for 50 hours, and its volume and mass change rate were measured. Three samples were tested in each group and the average value was taken.

[0083] Table 4

[0084] Hollow glass microsphere addition amount (wt%) 0 5 10 30 40 Rubber mass change rate (%) 23 20 15 10 4 Rubber volume change rate (%) 27 23 18 12 6

[0085] As shown in Table 4, with the increase of the content of hollow glass microspheres, the mass change rate of the modified butyl rubber film layer gradually decreased, and the volume change rate of the modified butyl rubber film layer also gradually decreased.

[0086] That is to say, the higher the content of the inorganic hollow microspheres, the lower the mass change rate of the modified butyl rubber film layer, and the lower the volume change rate of the modified butyl rubber film layer.

[0087] According to one embodiment of the present application, the strain recovery ratio of the modified butyl rubber film layer after the temperature is 23° C., the strain amount is 10%, and the relaxation time is 5 minutes is ≥69%.

[0088] The effect of the content of inorganic hollow microspheres in the diaphragm material on the strain recovery ratio is shown in Table 5 below.

[0089] Test method: Stress relaxation of butyl rubber with different mass fractions of inorganic hollow microspheres added at 10% strain.

[0090] Specifically, the butyl rubber compound was first vulcanized with a flat vulcanizer to obtain a vulcanized rubber sheet of 100mm×60mm×0.2mm. The vulcanization conditions were: temperature 155°C, time 15min, and pressure 12MPa. Then, a DMA stress relaxation test was performed. The test was performed in accordance with ASTM D5026-15. The fixture used during the test was a tensile fixture, the test temperature was 23°C, the strain was 10%, and the relaxation time was 5min. Three samples were tested for each set of data and the average value was taken.

[0091] Table 5

[0092] Hollow glass microsphere addition amount (wt%) 0 10 20 30 40 50 Strain recovery ratio (%) 65 71 76 80 82 85

[0093] As shown in Table 5, with the increase of hollow glass microsphere content, the strain recovery ratio of the modified butyl rubber film layer gradually increases.

[0094] In other words, by adding inorganic hollow microspheres to rubber, the diaphragm can have good resilience. After the inorganic hollow microspheres are mixed with rubber, the inorganic hollow microspheres are evenly dispersed inside the rubber, and the rubber molecules on the surface of the inorganic hollow microspheres are more likely to slide, thus making the diaphragm have good resilience.

[0095] In some specific embodiments of the present application, the density of the modified butyl rubber film layer is 0.5 g / cm 3 ~1g / cm 3 That is to say, by adding inorganic hollow microspheres to the polymer of isobutylene and isoprene to form a low-density rubber diaphragm material, and then adjusting the amount of inorganic hollow microspheres added, the density of the diaphragm can be controlled at 0.5g / cm 3 ~1.1g / cm 3 For example, the density of the modified butyl rubber film layer can be 0.5 g / cm 3 , 0.7g / cm 3 , 0.8g / cm 3 , 0.9g / cm 3 , 1g / cm 3 or 1.1 g / cm 3 As a result, the modified butyl rubber membrane layer can reduce weight by 30%-50%, which can achieve a good weight reduction effect and greatly improve the sound sensitivity of the diaphragm.

[0096] The influence of the content of inorganic hollow microspheres in the diaphragm material on the intermediate frequency Fr of the diaphragm is as follows: Figure 1 shown.

[0097] like Figure 1As shown in the figure, by testing the intermediate frequency Fr of the sound-generating device with diaphragms of different densities, it can be seen that as the density of the diaphragm increases, the intermediate frequency performance of the sound-generating device with the diaphragm gradually decreases. In other words, by adding inorganic hollow microbeads to the polymer of isobutylene and isoprene to prepare the diaphragm material, the density of the diaphragm can be reduced and the intermediate frequency performance of the sound-generating device can be improved.

[0098] It should be noted that when the density of the low-density rubber is low (<0.5 g / cm 3 ), the content of inorganic hollow microspheres is high, the prepared diaphragm has low elongation at break and low strength, and is prone to reliability problems such as collapse and film breakage. When the content of inorganic hollow microspheres is low, the density of the diaphragm is also high (>1g / cm 3 ).

[0099] The mid-frequency Fr curve of the diaphragm at different densities shows that the reduction of the diaphragm density can significantly improve the mid-frequency sensitivity. 3 When the hardness is the same, the content of inorganic hollow microspheres is higher and the mass proportion of other fillers is lower, which will lead to problems such as reduced aging resistance of rubber. When the diaphragm density is higher than 1g / cm 3 When the hardness is the same, the diaphragm weight reduction is not obvious, resulting in an insignificant improvement in the mid-range sensitivity. As the density increases, the mid-range performance gradually decreases.

[0100] According to one embodiment of the present application, the additives include a cross-linking agent, a reinforcing agent and an antioxidant, wherein the cross-linking agent is at least one of metal oxides, metal peroxides, sulfur, dithiocarbamate metal salts and thiourea vulcanization systems; the reinforcing agent is at least one of carbon black, white carbon black, calcium carbonate and nano titanium dioxide; the antioxidant is at least one of antioxidant N-445, antioxidant 246 and antioxidant 4010.

[0101] That is, the reinforcing agent includes one or more of carbon black, white carbon black, calcium carbonate, and nano titanium dioxide. The antioxidant includes one or more of antioxidant N-445, antioxidant 246, and antioxidant 4010, and the crosslinking agent is at least one of metal oxides, metal peroxides, sulfur, dithiocarbamate metal salts, and thiourea vulcanization systems.

[0102] In some specific embodiments of the present application, the content of the crosslinking agent is 0.5wt% to 5.5wt% of the rubber mix, the content of the reinforcing agent is 5wt% to 72wt% of the rubber mix, and the content of the antioxidant is 0.1wt% to 6.2wt% of the rubber mix.

[0103] Among them, the content of the crosslinking agent accounts for 0.5wt% to 5.5wt% of the mixed rubber, preferably 1wt% to 3wt%. The amount of the crosslinking agent directly determines the degree of crosslinking. When the content of the crosslinking agent in the system is lower than 0.5wt%, the degree of crosslinking of the rubber is low, the mechanical strength is low, and the mechanical properties of the material are difficult to meet the product requirements; when the content of the crosslinking agent is greater than 5.5wt%, the degree of crosslinking of the rubber is high, the elongation at break of the material is low, the toughness of the material is insufficient, and it is easy to become brittle and break during long-term use.

[0104] The content of antioxidant accounts for 0.1wt% to 6.2wt% of the rubber compound. During the use of rubber, as time goes by, the molecular chain breaks and produces free radicals, which accelerates its own aging. Antioxidants are added to stop the self-catalytic active free radicals produced in rubber products. Too little addition will not achieve the effect of extending the service life. Too much addition will cause the mechanical properties of the material to decrease because it cannot be well soluble in the elastomer and is difficult to disperse evenly. It is also easy to precipitate on the surface over time.

[0105] The content of the reinforcing agent accounts for 5wt% to 72wt% of the mixed rubber. The reinforcing agent interacts with the rubber molecular chain through mutual entanglement, van der Waals force or hydrogen bond to form an interface. When the material is subjected to force, the molecular chain is easier to slide on the surface of the reinforcing agent, but it is not easy to separate from the reinforcing agent. The rubber molecules and the reinforcing agent form a strong bond that can slide, and the mechanical strength is increased. However, excessive reinforcing agent causes the tensile strength of the material to increase significantly, and the elongation at break drops sharply, which cannot meet product requirements.

[0106] According to one embodiment of the present application, the tensile strength of the modified butyl rubber membrane layer when broken is 7MPa to 35MPa. That is, by adding inorganic hollow microspheres to the polymer of isobutylene and isoprene to form a low-density rubber diaphragm material, when the diaphragm material is broken, its tensile strength can be controlled within the range of 7MPa to 35MPa. For example, the tensile strength of the modified butyl rubber membrane layer can be 7MPa, 10MPa, 15MPa, 20MPa, 25MPa, 30MPa, or 35MPa.

[0107] In some specific embodiments of the present application, the tear strength of the modified butyl rubber film layer is 20N / mm to 60N / mm. That is to say, by adding inorganic hollow microbeads to the polymer of isobutylene and isoprene to form a low-density rubber diaphragm material, when the diaphragm material is pulled apart, the tear strength can be controlled within the range of 20N / mm to 60N / mm. The tear strength of the modified butyl rubber film layer can be 20N / mm, 30N / mm, 45N / mm, 50N / mm or 60N / mm. That is, the modified butyl rubber film layer can have better mechanical properties and is more conducive to improving the stability of the diaphragm.

[0108] According to one embodiment of the present application, the loss factor of the modified butyl rubber film layer at room temperature is greater than 0.11. That is to say, the loss factor of the modified butyl rubber film layer can be greater than 0.11, preferably greater than 0.13. The surface-modified inorganic hollow microspheres can be evenly dispersed in the butyl rubber matrix, and the amount added has little effect on the excellent damping properties of the rubber itself. Its damping value is greater than 0.11, preferably greater than 0.13, and the prepared diaphragm has a lower impedance curve. The speaker diaphragm has excellent damping properties, can effectively suppress the transient distortion of the speaker, can achieve high-fidelity effects of the speaker's electrical signals, and has good consistency in the vibration system.

[0109] Figure 2 The following are the test curves of vibration displacement at different positions of the diaphragm at different frequencies. The diaphragm is a rectangular folded ring diaphragm. The horizontal axis is the frequency (Hz), and the vertical axis is the loudness displacement (mm). Points were taken at the edge and center of the center of the diaphragm for testing. The curves in the figure are concentrated, and the vibration consistency of each part of the diaphragm is good. During the vibration process, the polarization vibration of the diaphragm is reduced, and the sound quality is excellent.

[0110] In some specific embodiments of the present application, the glass transition temperature of the modified butyl rubber film layer is ≤-10° C. The glass transition temperature can enable the diaphragm to maintain a high elastic state at room temperature and have good resilience.

[0111] Preferably, the glass transition temperature of the rubber membrane layer is ≤-15°C. When the temperature is below 0°C, the diaphragm can maintain good rubber elasticity in the working state, so that the speaker can show higher sound quality; at the same time, the risk of damage to the speaker diaphragm in a low temperature environment is reduced, and the reliability is higher. In addition, the lower glass transition temperature makes the material have high modulus consistency when working above the glass transition temperature, and the F0 (resonance frequency) of the diaphragm made of the diaphragm material has better stability in the whole temperature range.

[0112] According to an embodiment of the present application, the room temperature storage modulus of the modified butyl rubber film layer is 0.4 MPa to 36 MPa. In addition, the hardness of the low-density rubber ranges from 20A to 100A.

[0113] The speaker includes a vibration system and a magnetic circuit system that cooperates with the vibration system, and the vibration system includes the speaker diaphragm provided by the present application. For example, the diaphragm is a folded ring diaphragm or a flat diaphragm. The speaker has the characteristics of good sound effect and good durability.

[0114] In some embodiments of the present application, the hardness can be 35A to 80A, and the room temperature storage modulus is 0.5MPa to 35MPa, which enables the F0 of the speaker to reach 500Hz to 1500Hz, and the low-frequency performance of the speaker is excellent.

[0115] In some specific embodiments of the present application, the diaphragm is a single-layer structure, and the diaphragm is composed of a modified butyl rubber membrane layer.

[0116] According to an embodiment of the present application, the diaphragm is a composite layer structure, and the diaphragm further includes a membrane layer made of at least one of a thermoplastic elastomer, an engineering plastic, and a thermosetting elastomer. That is, when the diaphragm is a composite diaphragm, it can include a layer of modified butyl rubber membrane layer, or multiple layers of modified butyl rubber membrane layers, and the multiple layers of modified butyl rubber membrane layers can be arranged adjacent to each other or at intervals, and the specific arrangement method can be selected according to the specific design requirements of the sound-generating device.

[0117] The other composite layers of the composite film are at least one of thermoplastic elastomer, engineering plastic, and thermosetting elastomer, and the thermoplastic elastomer is selected from at least one of thermoplastic polyester elastomer, thermoplastic polyurethane elastomer, thermoplastic polyamide elastomer, and silicone elastomer.

[0118] The thermosetting elastomer is selected from at least one of natural rubber (NR), styrene-butadiene rubber (SBR), butadiene rubber (BR), isoprene rubber (IR), chloroprene rubber (CR), butyl rubber (IIR), nitrile rubber (NBR), chlorinated nitrile rubber (HNBR), ethylene-propylene rubber (EPDM), silicone rubber (Q), fluorosilicone rubber, fluororubber (FPM), polyurethane rubber (AU), acrylate rubber (ACM), ethylene-acrylate rubber (AEM), ethylene-vinyl acetate rubber (EVM), chlorosulfonated polyethylene rubber (CSM), epichlorohydrin rubber (CO) and polysulfide rubber.

[0119] The composite diaphragm composed of a film layer made of thermoplastic elastomer, engineering plastic and thermosetting elastomer and a modified butyl rubber film layer has excellent mechanical properties. While being able to ensure a certain mechanical strength, it also has a high damping value.

[0120] In summary, according to the diaphragm of the sound-emitting device of the embodiment of the present application, the modified butyl rubber membrane layer is prepared by cross-linking reaction after kneading inorganic hollow microbeads, additives and polymers of isobutylene and isoprene to form a mixed rubber, thereby improving the damping performance of the modified butyl rubber membrane layer. At the same time, the percentage change of the elastic modulus of the modified butyl rubber membrane layer to which inorganic hollow microbeads are added is reduced under high temperature environment, thereby reducing the number of swing vibrations of the diaphragm and making the resonant frequency of the diaphragm more stable. In addition, by controlling the amount of inorganic hollow microbeads added, the density of the diaphragm is reduced, and the diaphragm has excellent aging resistance, thereby improving the mid-frequency performance and performance of the sound-emitting device.

[0121] It should be noted that the diaphragm provided in the present application can form a sound-generating device of any structure, such as the following typical sound-generating device: including a vibration system and a magnetic circuit system matched with the vibration system, the vibration system including a diaphragm and a voice coil combined with one side of the diaphragm. When the sound-generating device is working, after the voice coil is energized, under the action of the magnetic field force of the magnetic circuit system, the voice coil can vibrate up and down to drive the diaphragm to vibrate, and the diaphragm can produce sound when it vibrates.

[0122] According to the second aspect of the embodiment of the present application, the sound-emitting device 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 produce sound, and the diaphragm is the diaphragm of the above-mentioned embodiment.

[0123] like Figure 3 and Figure 4 As shown, the sound-generating device includes a diaphragm 15 prepared by the above-mentioned embodiment of the present application, and the diaphragm 15 can be composed of a folding ring portion 151 and a dome portion 152, and the modified butyl rubber membrane layer can be applied to the folding ring portion 151 of the diaphragm. Those skilled in the art can make corresponding adjustments according to actual product requirements, such as the folding ring portion 151 protrudes toward the voice coil 11 side, the dome portion 152 is located on the lower surface of the folding ring portion 151, and a centering support is added to the vibration system.

[0124] According to the sound-generating device of the third aspect of the present application, Figure 5 and Figure 6 As shown, it 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 make a 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-mentioned embodiment.

[0125] That is to say, the sound-generating device 100 according to the embodiment of the present application may also include two diaphragms prepared by the embodiment of the present application, namely, a first diaphragm 12 and a second diaphragm 13. The first diaphragm 12 may be used to vibrate and generate sound, and the second diaphragm 13 may be used to balance the vibration of the voice coil 11. Specifically, when the sound-generating device 100 is working, after the voice coil 11 is energized, under the action of the magnetic field force of the magnetic circuit system 14, the voice coil 11 may vibrate up and down to drive the first diaphragm 12 to vibrate, and the first diaphragm 12 may generate sound when vibrating. The second diaphragm 13 may 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 may balance the vibration of the voice coil 11, and may prevent the voice coil 11 from polarizing, thereby improving the sound-generating effect of the sound-generating device 100.

[0126] It should be noted that the first diaphragm 12 and the second diaphragm 13 may both adopt the diaphragms of the embodiment of the present application, or one of the first diaphragm 12 or the second diaphragm 13 may adopt the diaphragm of the embodiment of the present application, and this is not specifically limited.

[0127] The diaphragm of the sound-generating device of the present application is described in detail below in conjunction with specific embodiments.

[0128] Embodiment 1

[0129] The formula is shown in Table 6 by weight, and after mixing according to the formula, a cross-linking reaction is performed to form a diaphragm material. The diameter of the hollow glass microspheres is 60 μm to 70 μm.

[0130] Table 6

[0131]

[0132] Comparative Example 1

[0133] The formula is shown in Table 7 in parts by mass, and after mixing according to the formula, a cross-linking reaction is performed to form a diaphragm material.

[0134] Table 7

[0135]

[0136] First, the raw materials of Example 1 and Comparative Example 1 were weighed according to the above ratios. The raw materials of Example 1 and Comparative Example 1 were mixed in an internal mixer to obtain the mixed rubber corresponding to Example 1 and the mixed rubber corresponding to Comparative Example 1.

[0137] Then, a portion of the mixed rubber corresponding to Example 1 and Comparative Example 1 was taken out respectively, and the density thereof was measured.

[0138] Subsequently, the mixed rubber was vulcanized using a flat plate vulcanizer to obtain a vulcanized rubber sheet of 100 mm×60 mm×0.3 mm, wherein the vulcanization conditions were: temperature 155°C, time 15 min, and pressure 12 MPa.

[0139] Next, every three films of Example 1 were grouped into a control group and a baking group. Similarly, every three films of Comparative Example 1 were grouped into a control group and a baking group. After the grouping was completed, the baking groups of Example 1 and Comparative Example 1 were placed in a constant temperature and humidity oven. The test conditions were: temperature 90°C, humidity 60%, and test time 16h.

[0140] After baking, the control group and the baking group of Example 1 and Comparative Example 1 were tested for tensile properties. The test conditions were as follows: the test was conducted according to the ASTM D412-2016 test standard, and the percentage change of the elastic modulus after baking relative to the elastic modulus of the unbaked was calculated. The average value was taken for each group, and the test results were as follows:

[0141] Table 8

[0142]

[0143] It can be seen from the test results that the percentage change of the elastic modulus corresponding to Example 1 is less than the percentage change of the elastic modulus of Comparative Example 1. The density corresponding to Example 1 is less than the density corresponding to Comparative Example 1. Since the strength of inorganic hollow microspheres is relatively high, the content of reinforcing agent in the rubber with inorganic hollow microspheres added is less than that of ordinary rubber at the same hardness, so that the rubber content is increased, and the work required to overcome the internal friction is increased, so that the rubber has better damping performance. At the same time, inorganic hollow microspheres have excellent high temperature resistance, so that the percentage change of the elastic modulus of the implementation case of this application is less than that of conventional butyl rubber under high temperature and high humidity environment, which can better reduce the swing vibration of the diaphragm, make the stability of the diaphragm F0 better, and ensure the use effect of the diaphragm and the acoustic performance of the sound-generating device.

[0144] Although some specific embodiments of the present application have been described in detail by way of example, it should be understood by those skilled in the art that the above examples are only for illustration, not for limiting 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 diaphragm of a sound-generating device, It is characterized in that The diaphragm includes at least one modified butyl rubber membrane layer, which is prepared by mixing inorganic hollow microspheres, additives, and polymers of isobutylene and isoprene to form a mixed rubber and then subjecting it to a cross-linking reaction; The diameter of the inorganic hollow microspheres is 10 μm to 100 μm, and the distribution density of the inorganic hollow microspheres in the modified butyl rubber film layer is 0.15 g / cm 3 ~0.9g / cm 3 , the compressive strength of the inorganic hollow microspheres is ≥50MPa, and the elastic modulus change percentage of the modified butyl rubber film layer under the conditions of a temperature of 90°C and a humidity of 60% is ≤9.6%; The content of the inorganic hollow microspheres accounts for 5wt% to 55wt% of the total amount of the mixed rubber.

2. The diaphragm of the sound-generating device according to claim 1, It is characterized in that After the modified butyl rubber film layer is aged in hot air at 150° C. for 16 hours, the tensile strength decrease rate of the modified butyl rubber film layer is ≤51%, and the elongation at break decrease rate is ≤72%.

3. The diaphragm of the sound-generating device according to claim 1, It is characterized in that The mass change rate of the modified butyl rubber film layer after being immersed in a polar solvent for 50 hours is ≤23%.

4. The diaphragm of the sound-generating device according to claim 1, It is characterized in that The modified butyl rubber film layer has a strain recovery ratio of ≥69% at 23° C., a strain amount of 10%, and a relaxation time of 5 minutes.

5. The diaphragm of the sound-generating device according to claim 1, It is characterized in that The density of the modified butyl rubber film layer is 0.5 g / cm 3 ~1.1g / cm 3 .

6. The diaphragm of the sound-generating device according to claim 1, It is characterized in that The additives include crosslinking agents, reinforcing agents and antioxidants. Among them, the cross-linking agent is at least one of metal oxides, metal peroxides, sulfur, dithiocarbamate metal salts and thiourea vulcanization systems; the reinforcing agent is at least one of carbon black, white carbon black, calcium carbonate and nano titanium dioxide; the antioxidant is at least one of antioxidant N-445, antioxidant 246 and antioxidant 4010.

7. The diaphragm of the sound-generating device according to claim 6, It is characterized in that The content of the cross-linking agent accounts for 0.5wt%~5.5wt% of the rubber mix, the content of the reinforcing agent accounts for 5wt%~72wt% of the rubber mix, and the content of the antioxidant accounts for 0.1wt%~6.2wt% of the rubber mix.

8. The diaphragm of the sound-generating device according to claim 1, It is characterized in that The loss factor of the modified butyl rubber film layer at room temperature is greater than 0.

11.

9. The diaphragm of the sound-generating device according to claim 1, It is characterized in that The glass transition temperature of the modified butyl rubber film layer is ≤-10°C.

10. The diaphragm of the sound-generating device according to claim 1, It is characterized in that The diaphragm is a single-layer structure, and the diaphragm is composed of a layer of the modified butyl rubber membrane.

11. The diaphragm of the sound-generating device according to claim 1, It is characterized in that The diaphragm is a composite layer structure, and the diaphragm also includes a membrane layer made of at least one of thermoplastic elastomer, engineering plastic and thermosetting elastomer.

12. A sound-generating device, It is characterized in that It comprises a vibration system and a magnetic circuit system matched with the vibration system, the vibration system comprises 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 the diaphragm described in any one of claims 1-11.

13. A sound-generating device, It is 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 described in any one of claims 1-11.

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