Diaphragm of sound-generating device and sound-generating device

Abstract

The present application discloses a diaphragm of a sound-generating device and a sound-generating device. The diaphragm includes at least one modified styrene-butadiene rubber membrane layer, which is prepared by mixing inorganic hollow microspheres, additives, and polystyrene-butadiene copolymer to form a mixed rubber and then cross-linking the mixed rubber. The diameter of the inorganic hollow microspheres is 10 μm to 100 μm, and the distribution density of the inorganic hollow microspheres in the diaphragm is 0.15 g / cm 3 ~0.9g / cm 3 The strain recovery ratio of the diaphragm after relaxation for 5 minutes at 23°C and 10% strain is ≥70%. This invention uses a modified styrene-butadiene rubber membrane layer prepared by cross-linking inorganic hollow microspheres, additives, and polystyrene butadiene copolymer to form a rubber compound. This improves the resilience of the diaphragm material, reduces the density of the diaphragm, and improves the mid-frequency sensitivity of the sound-generating device.

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] With the increasing demand for high power, waterproof performance and high sound quality of speakers, rubber diaphragms have also been widely used in the field of speakers. However, due to the high density of rubber diaphragms (≥1.2g / cm 3 ), and the high thickness results in a large diaphragm mass. Consequently, the high vibration mass of a rubber diaphragm in a vibration system results in a low intermediate frequency (Fr) (frequency response) of the sound-generating device. Furthermore, existing diaphragms have relatively low strain recovery, making it impossible to achieve good rebound performance.

[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 styrene-butadiene rubber membrane layer, which is prepared by mixing inorganic hollow microspheres, additives and polystyrene butadiene copolymer to form a mixed rubber and then undergoing a cross-linking reaction, 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 styrene-butadiene rubber membrane layer is 0.15 g / cm 3 ~0.9g / cm 3 The modified styrene-butadiene rubber film layer has a strain recovery ratio of ≥70% after relaxation for 5 minutes at 23° C. and a strain of 10%.

[0008] According to some embodiments of the present application, the compressive strength of the inorganic hollow microspheres is ≥10 MPa.

[0009] According to some embodiments of the present application, the content of the inorganic hollow microspheres accounts for 5 wt % to 50 wt % of the total amount of the rubber mix.

[0010] According to some embodiments of the present application, the glass transition temperature of the modified styrene-butadiene rubber film layer is ≤-15°C.

[0011] According to some embodiments of the present application, the surface energy of the modified styrene-butadiene rubber film layer is ≤58 J / m 2 .

[0012] According to some embodiments of the present application, after the modified styrene-butadiene rubber film layer is aged in hot air at 150° C. for 16 hours, the tensile strength of the modified styrene-butadiene rubber film layer decreases by ≤50%, and the elongation at break decreases by ≤70%.

[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 sulfur, phenolic resin and organic peroxide; the reinforcing agent is at least one of carbon black, white carbon black, calcium carbonate and nano titanium dioxide; and 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 crosslinking agent accounts for 0.5wt% to 5wt% of the rubber mix, the content of the reinforcing agent accounts for 5wt% to 70wt% of the rubber mix, and the content of the antioxidant accounts for 0.1wt% to 6wt% of the rubber mix.

[0015] According to some embodiments of the present application, the loss factor of the modified styrene-butadiene rubber film layer at room temperature is greater than 0.12.

[0016] According to some embodiments of the present application, the density of the modified styrene-butadiene rubber film layer is 0.4 g / cm 3 ~1.1g / cm 3 .

[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 styrene-butadiene rubber membrane.

[0018] According to some embodiments 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.

[0019] According to the second aspect of the embodiment of the present application, the sound-producing 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-producing 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 produce sound. The two ends of the second diaphragm are respectively connected to the shell and the bottom of the voice coil. The second diaphragm is the diaphragm according to the above-mentioned embodiment of the present application.

[0021] The diaphragm of the sound-generating device according to the embodiments of the present application is made of a modified styrene-butadiene rubber membrane layer prepared by cross-linking a rubber mixture formed by mixing inorganic hollow microspheres, additives, and polystyrene butadiene copolymer. This ensures a certain mechanical strength of the diaphragm material while reducing the density of the diaphragm and improving the mid- and high-frequency sensitivity of the sound-generating device. Furthermore, after mixing the inorganic hollow microspheres with the rubber, they are evenly dispersed within the rubber, making it easier for the rubber molecules on the surface of the inorganic hollow microspheres to slide, thereby imparting good resilience to the diaphragm.

[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 is a curve showing the relationship between the amount of inorganic hollow microspheres added and the tear strength of the diaphragm of the sound-generating device according to an embodiment of the present application;

[0025] Figure 2 : is a mid-frequency Fr (frequency response) curve of the modified styrene-butadiene rubber membrane layer with different densities of the diaphragm of the sound-generating device according to an embodiment of the present application;

[0026] Figure 3 1 is a test curve of vibration displacement of different parts of the diaphragm of the sound-generating device at different frequencies according to an embodiment of the present application;

[0027] Figure 4 Schematic diagram of the overall structure of the sound-generating device according to an embodiment of the present application;

[0028] Figure 5 is a schematic diagram of a partial structure of a sound-generating device according to an embodiment of the present application;

[0029] Figure 6 is a cross-sectional view of a sound-generating device according to an embodiment of the present application;

[0030] Figure 71 is an exploded view of a sound-generating device according to an embodiment of the present application.

[0031] Reference numerals

[0032] Sound-generating device 100;

[0033] Housing 10; voice coil 11; first diaphragm 12; second diaphragm 13; magnetic circuit system 14;

[0034] Diaphragm 15 ; surround 151 ; dome 152 . DETAILED DESCRIPTION

[0035] Various exemplary embodiments of the present application will now be described in detail with reference to the accompanying drawings. It should be noted that unless otherwise specifically stated, the relative arrangements of components and steps, numerical expressions and numerical values set forth in these embodiments do not limit the scope of the present application.

[0036] The following description of at least one exemplary embodiment is merely illustrative in nature and is in no way intended to limit the present disclosure, its application, or uses.

[0037] Technologies, methods, and equipment known to ordinary technicians in the relevant art may not be discussed in detail, but where appropriate, the technologies, methods, and equipment should be considered part of the specification.

[0038] In all examples shown and discussed herein, any specific values should be interpreted as merely exemplary and not limiting. Therefore, other examples of the exemplary embodiments may have different values.

[0039] It should be noted that like reference numerals and letters refer to like items in the following figures, and therefore, once an item is defined in one figure, it need not be further discussed in subsequent figures.

[0040] The diaphragm of the sound-emitting device according to the embodiment of the present application is described in detail below with reference to the accompanying drawings.

[0041] According to the diaphragm of the sound-generating device of the embodiment of the present application, the diaphragm includes at least one modified styrene-butadiene rubber membrane layer, which is prepared by mixing inorganic hollow microspheres, additives and polystyrene butadiene copolymer to form a mixed rubber and then undergoing a cross-linking reaction, 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 diaphragm is 0.15 g / cm 3 ~0.9g / cm 3 , the strain recovery ratio of the diaphragm after relaxation for 5 minutes at 23℃ and 10% strain is ≥70%.

[0042] The diaphragm of the sound-emitting device according to the embodiment of the present application is composed of at least one layer of modified styrene-butadiene 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 styrene-butadiene 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 styrene-butadiene rubber membrane layer, and the diaphragm is a composite of a modified styrene-butadiene rubber membrane layer and a membrane layer of other materials. Optionally, when the diaphragm contains multiple layers of modified styrene-butadiene rubber membrane layers, two adjacent layers of modified styrene-butadiene rubber membrane layers can be spaced apart, that is, a membrane layer of other materials can also be set between two adjacent layers of modified styrene-butadiene rubber membrane layers. Of course, two adjacent layers of modified styrene-butadiene rubber membrane layers can also be set in contact with each other. The setting can be selected according to actual usage requirements, and the present application does not impose specific restrictions on this.

[0043] Specifically, the polystyrene butadiene copolymer in the present application may be a copolymer of 1,3-butadiene and styrene, represented by the following chemical formula (I):

[0044]

[0045] In formula (I), x, y, and z are natural numbers.

[0046] The modified styrene-butadiene rubber membrane layer is made by adding inorganic hollow microbeads to polystyrene-butadiene copolymer. Specifically, a rubber mix can be formed by kneading the inorganic hollow microbeads, additives and polystyrene-butadiene copolymer. After the rubber mix is vulcanized, a modified styrene-butadiene rubber membrane layer can be formed. In other words, polystyrene-butadiene copolymer can form styrene-butadiene rubber, which is equivalent to the base material of the diaphragm material. After the inorganic hollow microbeads and polystyrene-butadiene copolymer have undergone the kneading process, the inorganic hollow microbeads can be dispersed in the base material. Since the density of inorganic hollow microbeads is relatively low, by adding inorganic hollow microbeads to the rubber, the density of the diaphragm material can be reduced to obtain a low-density diaphragm.

[0047] Under the condition that the diaphragm material with added inorganic hollow microbeads in the present application has the same hardness as the styrene-butadiene rubber diaphragm material without added inorganic hollow microbeads in the prior art, the diaphragm of the present application has a lower diaphragm density, which can reduce the vibration mass of the diaphragm system, thereby making the sound-emitting device have better mid- and high-frequency sensitivity.

[0048] 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, as well as 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 it into 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 sound effect in a high temperature environment. In addition, inorganic hollow microspheres are very excellent thermal insulation materials that can effectively block external heat and effectively slow down the damage of external heat to the internal network structure of the rubber.

[0049] Furthermore, the diameter of the inorganic hollow microspheres is 10 μm to 100 μm, preferably 15 μm to 70 μm. For example, the particle size of the inorganic hollow microspheres can be 10 μm, 15 μm, 20 μm, 30 μm, 40 μm, 50 μm, 60 μm, 70 μm, 80 μm, 90 μm or 100 μm. In other words, inorganic hollow microspheres of different particle sizes can be selected according to the thickness of the diaphragm to ensure that the inorganic hollow microspheres are evenly dispersed in the substrate.

[0050] In addition, as the diameter of the inorganic hollow microspheres decreases, the distribution density of the inorganic hollow microspheres will increase. The distribution density of the inorganic hollow microspheres can be controlled at 0.15 g / 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 , 0.35g / 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 density of the diaphragm, the distribution density of the inorganic hollow microspheres is preferably 0.25 g / cm 3 ~0.8g / cm 3 The mechanical properties of the material are affected by the diameter of the inorganic hollow microspheres. As the diameter of the hollow microspheres increases, the mechanical properties of the material decrease. This is because under the same surface treatment conditions, the smaller the diameter of the inorganic hollow microspheres, the larger the specific surface area, and the better the compatibility with the modified styrene-butadiene rubber, allowing the inorganic hollow microspheres to be evenly dispersed in the rubber.

[0051] Furthermore, the diaphragm has a strain recovery ratio of ≥70% after 5 minutes of relaxation at 23°C and 10% strain. Specifically, the diaphragm with the addition of inorganic hollow microspheres has excellent resilience. After the inorganic hollow microspheres are mixed with rubber, they are evenly dispersed within the rubber. The rubber molecules on the surface of the inorganic hollow microspheres are more likely to slide, thus giving the diaphragm excellent resilience.

[0052] As shown in Table 1, the stress relaxation of styrene-butadiene rubber with different mass fractions of inorganic hollow microspheres added under 10% strain, the inorganic hollow microspheres here are hollow glass microspheres. It should be noted that hollow glass microspheres are a type of inorganic hollow microspheres. The use of hollow glass microspheres or other inorganic hollow microspheres can also reflect the role of inorganic hollow microspheres in the material.

[0053] First, styrene-butadiene rubber was vulcanized using a flat plate vulcanizer to produce a vulcanized sheet measuring 100 mm x 60 mm x 0.2 mm. The vulcanization conditions were: temperature 150°C, time 20 minutes, and pressure 12 MPa. DMA stress relaxation testing was then performed according to ASTM D5026-15. Using a tensile fixture, the test temperature was 23°C, the strain was 10%, and the relaxation time was 5 minutes. Three samples were tested for each data set, and the average was taken. The results are as follows:

[0054] Table 1

[0055]

[0056] Table 1 shows that the higher the percentage of hollow glass microspheres, the greater the strain recovery ratio of the modified styrene-butadiene rubber membrane. The strain recovery ratio can be used to characterize the resilience of the modified styrene-butadiene rubber membrane; a higher strain recovery ratio indicates better resilience. In other words, a higher percentage of inorganic hollow microspheres improves the diaphragm's resilience, reducing reliability issues like membrane breakage while also ensuring the acoustic performance of the sound-generating device.

[0057] Thus, the diaphragm of the sound-generating device according to the embodiment of the present application is made of a modified styrene-butadiene rubber membrane layer prepared by cross-linking a rubber mixture formed by mixing inorganic hollow microspheres, additives, and polystyrene butadiene copolymer. This ensures that the diaphragm material has a certain mechanical strength while reducing the density of the diaphragm and improving the mid- and high-frequency sensitivity of the sound-generating device. Furthermore, after being mixed with the rubber, the inorganic hollow microspheres are evenly dispersed within the rubber, making it easier for the rubber molecules on the surface of the inorganic hollow microspheres to slide, thereby giving the diaphragm good resilience.

[0058] According to one embodiment of the present application, the compressive strength of the inorganic hollow microspheres is ≥10 MPa. This high compressive strength not only prevents the inorganic hollow microspheres from being crushed during the mixing process, but also effectively increases the tensile strength of the modified styrene-butadiene rubber membrane when added to the styrene-butadiene rubber. This high mechanical strength of the diaphragm ensures that it will not be overstretched due to excessive driving forces in extreme environments, further ensuring the effectiveness of the diaphragm.

[0059] In some specific embodiments of the present application, the density of the modified styrene-butadiene rubber film layer is ≤1.29 g / cm 3 Preferably, the density of the modified styrene-butadiene rubber film layer is 0.61 / cm 3 ~1.14g / cm 3 . The introduction of inorganic hollow microspheres has greatly reduced the density of rubber. The modified styrene-butadiene rubber film layer can reduce the weight by 30%-50%, which has a good weight reduction effect. Table 2 shows the effect of the content of inorganic hollow microspheres on the density of rubber. The rubber density is measured by a density balance. Three samples are tested for each group of values, and the average value of the three samples is taken. The inorganic hollow microspheres here are hollow glass microspheres. It should be noted that hollow glass microspheres are a type of inorganic hollow microspheres. The use of hollow glass microspheres or other inorganic hollow microspheres can also reflect the role of inorganic hollow microspheres in the material.

[0060] Table 2

[0061] Hollow glass microsphere addition amount (wt%) 0 10 20 30 40 50 <![CDATA[Rubber density (g / cm 3 )]]> 1.29 1.14 0.83 0.74 0.61 0.57

[0062] As can be seen in Table 2, as the percentage of hollow glass microspheres increases, the density of the rubber gradually decreases. This means that the inorganic hollow microspheres can be evenly dispersed in the base material. By adding inorganic hollow microspheres to the rubber, the density of the diaphragm material can be reduced, resulting in a low-density diaphragm. This allows the diaphragm to maintain its hardness while reducing its density, thus ensuring a balance between hardness and density, ultimately achieving better sound quality.

[0063] According to one embodiment of the present application, the content of the inorganic hollow microspheres accounts for 5 wt % to 50 wt % of the total amount of the rubber mix.

[0064] In other words, inorganic hollow microspheres can be added to the polystyrene butadiene copolymer at a level of 5wt% to 50wt% of the total rubber mix. As the amount of inorganic hollow microspheres added increases, the density of the modified styrene butadiene rubber membrane decreases. By controlling the amount of inorganic hollow microspheres added, a diaphragm material with desired performance can be obtained. For example, the content of inorganic hollow microspheres can be 5wt%, 10wt%, 15wt%, 20wt%, 30wt%, 40wt%, or 50wt%, etc., and can be selected based on actual production needs.

[0065] Among them, inorganic hollow microspheres are an inorganic filler, and the bonding force between rubber and inorganic hollow microspheres is relatively poor. At the same time, the inorganic hollow microspheres themselves are cavitation materials, which are a defect in the rubber. When the rubber is stretched, it is equivalent to reducing the cross-sectional area of the material, resulting in a decrease in tear strength. Too low tear strength can lead to reliability problems such as film breakage. In other words, when the mass proportion of inorganic hollow microspheres is low, the reinforcement effect on rubber is not obvious. If the mass proportion is too high, it will cause the rubber to tear and the strength to be greatly reduced. Therefore, when the mass proportion of inorganic hollow microspheres is 5wt% to 50wt%, preferably, when the mass proportion of inorganic hollow microspheres is 10wt% to 40wt%, the above problems can be avoided.

[0066] Figure 1 The effect of the addition amount of inorganic hollow microspheres on the tear strength of the modified styrene-butadiene rubber film layer is shown.

[0067] First, the styrene-butadiene rubber compound was vulcanized using a flat vulcanizer to obtain a vulcanized film of 100mm×100mm×2mm. The vulcanization conditions were: temperature 150°C, time 20min, and pressure 12MPa. Then, the obtained film was subjected to a rubber tear test. The tear strength was prepared into rectangular samples according to the ASTM D624-00 (2020) test standard. Five samples were tested in each group and the average value was taken. Figure 1 It can be seen that the more inorganic hollow microspheres are added, the smaller the rubber tear strength is.

[0068] Therefore, by using a modified styrene-butadiene rubber membrane layer prepared by adding 5wt% to 50wt% of inorganic hollow microbeads to the total rubber mix as the diaphragm material, the density and strength of the diaphragm can be achieved at the same time, effectively ensuring the excellent mid- and high-frequency performance of the diaphragm.

[0069] In some specific embodiments of the present application, the density of the modified styrene-butadiene rubber film layer is 0.4 g / cm 3 ~1.1g / cm 3 In other words, by adding inorganic hollow microspheres to polystyrene butadiene copolymer to form a low-density rubber diaphragm material, and then adjusting the amount of inorganic hollow microspheres added, the density of the modified styrene butadiene rubber membrane layer can be controlled at 0.4g / cm 3 ~1.1g / cm 3 For example, the density of the modified styrene-butadiene rubber film layer can be 0.4 g / cm 3 , 0.5g / cm 3 , 0.6g / cm 3 , 0.7g / cm 3 , 0.8g / cm 3 , 0.9g / cm 3, 1g / cm 3 or 1.1 g / cm 3 .

[0070] Figure 2 The figure shows the comparison of Fr curves of modified styrene-butadiene rubber film layers with different distribution densities of inorganic hollow microspheres at the same hardness.

[0071] Because inorganic hollow microspheres are relatively strong, under conditions of equal rubber hardness, the reinforcing agent content of rubber containing inorganic hollow microspheres is lower than that of ordinary rubber. This increases the rubber content, which in turn increases the work required to overcome internal friction, thereby improving the intermediate frequency (Fr), reducing the swaying vibration of the diaphragm, and improving the sound quality. In other words, the intermediate frequency (Fr) of the modified styrene-butadiene rubber membrane layer can be increased by adding inorganic hollow microspheres.

[0072] According to one embodiment of the present application, the surface energy of the modified styrene-butadiene rubber film layer is ≤58 J / m 2 Preferably, the surface energy of the modified styrene-butadiene rubber film layer is ≤55 J / m 2 , the diaphragm thickness is 80μm~4000μm.

[0073] Specifically, small molecule compounds within the rubber migrate to the rubber surface during high-temperature molding. Repeated molding results in a growing accumulation of these compounds on the mold. Physical adsorption occurs between the small molecule compounds on the rubber surface and those on the mold, leading to sticking. Inorganic hollow microspheres are sufficiently rigid to effectively prevent the migration of these small molecule compounds, significantly slowing the sticking of the diaphragm and reducing the surface energy of the modified styrene-butadiene rubber membrane.

[0074] Table 3 shows the surface energy and water drop angle of modified styrene-butadiene rubber films with different inorganic hollow microsphere contents. Hollow glass microspheres are used as the inorganic hollow microspheres here. It should be noted that hollow glass microspheres are a type of inorganic hollow microsphere. Using hollow glass microspheres or other inorganic hollow microspheres can equally demonstrate the role played by inorganic hollow microspheres in the material.

[0075] First, the styrene-butadiene rubber mix was vulcanized using a flat plate vulcanizer to produce a vulcanized sheet measuring 100 mm x 100 mm x 0.2 mm. The vulcanization conditions were: temperature 170°C, time 200 seconds, and pressure 12 MPa. The resulting sheet was then subjected to a water drop angle test according to GB / T 30693-2014. Five points were measured on the sheet, and the average value was calculated.

[0076] Table 3

[0077]

[0078]

[0079] As shown in Table 3, the water drop angle of the modified styrene-butadiene rubber film increases with increasing hollow glass microsphere content. The water drop angle is the surface contact angle. When the hollow glass microsphere content is zero, the water drop angle of the modified styrene-butadiene rubber film is only 65°.

[0080] Specifically, as the content of inorganic hollow microspheres increases, the angle of the water droplet gradually increases, and the surface energy of the modified styrene-butadiene rubber film layer gradually decreases. Since the inorganic hollow microspheres have high rigidity and can form a dense protective layer on the rubber surface, they can effectively prevent the migration of small molecule compounding agents and greatly slow down the mucous membrane state of the modified styrene-butadiene rubber film layer, thereby reducing the difficulty of demolding the diaphragm.

[0081] In some specific embodiments of the present application, after the modified styrene-butadiene rubber film layer is aged in hot air at 150° C. for 16 hours, the tensile strength of the modified styrene-butadiene rubber film layer decreases by ≤50%, and the elongation at break decreases by ≤70%.

[0082] In other words, the addition of inorganic hollow microspheres can significantly increase the modulus of the modified styrene-butadiene rubber film after the rubber is baked. Inorganic hollow microspheres have excellent high-temperature resistance and will not decompose under high temperature conditions while maintaining high strength, thus effectively improving the aging resistance of the modified styrene-butadiene rubber film.

[0083] Table 4 shows the percentage decrease in tensile strength and elongation at break of the styrene-butadiene rubber film layer modified with different mass fractions of inorganic hollow microspheres after baking at 150°C for 16 hours. The inorganic hollow microspheres here are hollow glass microspheres. It should be noted that hollow glass microspheres are a type of inorganic hollow microspheres. The use of hollow glass microspheres or other inorganic hollow microspheres can also reflect the role of inorganic hollow microspheres in the material.

[0084] First, the styrene-butadiene rubber mix was vulcanized using a flat plate vulcanizer to obtain a vulcanized film measuring 100 mm × 100 mm × 2 mm. The vulcanization conditions were: temperature 150°C, time 20 minutes, and pressure 12 MPa. The resulting film was then subjected to tensile and tear tests. Tensile strength was measured using dumbbell-shaped samples prepared according to the ASTM D412-2016 test standard. Five samples were tested for each set of data, and the average value was taken. Tear strength was measured using rectangular samples prepared according to the ASTM D624-00 (2020) test standard. Five samples were tested for each set of data, and the average value was taken.

[0085] Table 4

[0086] Hollow glass microsphere addition amount (wt%) 0 5 15 20 30 40 Percentage decrease in tensile strength after aging (%) 53.3 50.2 45.1 41.5 37.6 32.1 Percentage decrease of elongation at break (%) 76 69.5 65.4 53.2 46.2 43.5

[0087] As shown in Table 4, the percentage decrease in tensile strength after aging for the modified styrene-butadiene rubber film layer with 0 hollow glass microspheres added is greater than the percentage decrease in tensile strength after aging for the modified styrene-butadiene rubber film layer with a certain amount of hollow glass microspheres added. The percentage decrease in elongation at break after aging for the modified styrene-butadiene rubber film layer with 0 hollow glass microspheres added is greater than the percentage decrease in elongation at break after aging for the modified styrene-butadiene rubber film layer with a certain amount of hollow glass microspheres added. As the amount of hollow glass microspheres added increases, the percentage decrease in tensile strength and elongation at break of the modified styrene-butadiene rubber film layer after aging gradually decreases, and the aging resistance of the modified styrene-butadiene rubber film layer is improved.

[0088] That is, in extreme environments, the inorganic hollow microspheres have good high temperature resistance, will not decompose under high temperature conditions, and will maintain high strength, thereby effectively improving the aging resistance of the modified styrene butadiene rubber film layer. The modified styrene butadiene rubber film layer of the present application can also have good physical and chemical properties.

[0089] 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 sulfur, phenolic resin and organic peroxide; the reinforcing agent is at least one of carbon black, white carbon black, calcium carbonate and nano titanium dioxide; and the antioxidant is at least one of antioxidant N-445, antioxidant 246 and antioxidant 4010.

[0090] In some specific embodiments of the present application, the content of the crosslinking agent is 0.5wt% to 5wt% of the rubber mix, the content of the reinforcing agent is 5wt% to 70wt% of the rubber mix, and the content of the antioxidant is 0.1wt% to 6wt% of the rubber mix.

[0091] The crosslinking agent content accounts for 0.5wt% to 5wt% of the rubber mix, preferably 1wt% to 3wt%. The amount of crosslinking agent used directly determines the degree of crosslinking. When the crosslinking agent content in the system is less than 0.5wt%, the rubber has a low degree of crosslinking, low mechanical strength, and the mechanical properties of the material cannot meet product requirements. When the crosslinking agent content exceeds 5wt%, the rubber has a high degree of crosslinking, low elongation at break, insufficient toughness, and is prone to brittle fracture during long-term use.

[0092] The antioxidant content is 0.1-6% by weight of the rubber mix. Over time, rubber molecular chains break, generating free radicals that accelerate aging. Antioxidants are added to stop the generation of autocatalytic free radicals within rubber products. Too little antioxidant addition will not extend the product's service life, while too much antioxidant will not dissolve well in the elastomer, making it difficult to disperse evenly, leading to a decrease in the material's mechanical properties. Furthermore, antioxidants tend to precipitate on the surface over time.

[0093] The reinforcing agent accounts for 5% to 70% of the rubber mix. The reinforcing agent interacts with the rubber molecular chains through entanglement, van der Waals forces, or hydrogen bonds. When the material is subjected to stress, the molecular chains easily slide on the reinforcing agent surface but are difficult to separate from the reinforcing agent. The rubber molecules and the reinforcing agent form a strong bond that allows sliding, increasing the mechanical strength. However, excessive reinforcing agent significantly increases the tensile strength of the material and sharply reduces the elongation at break, which cannot meet product requirements.

[0094] According to one embodiment of the present application, the tensile strength of the modified styrene-butadiene rubber film layer when broken is 6 MPa to 37 MPa.

[0095] That is to say, a low-density rubber diaphragm material is formed by adding inorganic hollow microbeads to polystyrene butadiene copolymer. When the modified styrene butadiene rubber membrane layer is broken, its tensile strength can be controlled within the range of 6MPa to 37MPa, including endpoint values. For example, the tensile strength of the modified styrene butadiene rubber can be 2MPa, 6MPa, 10MPa, 16MPa, 20MPa, 25MPa, 30MPa, 40MPa or 45MPa, etc.

[0096] In some specific embodiments of the present application, the tear strength of the modified styrene-butadiene rubber membrane layer is 20 N / mm to 60 N / mm. The tear strength of the modified styrene-butadiene rubber can be 20 N / mm, 30 N / mm, 45 N / mm, 50 N / mm, 55 N / mm, or 60 N / mm, etc. The modified styrene-butadiene rubber membrane layer can have suitable mechanical properties, and the diaphragm prepared therefrom is less likely to break during use in a sound-generating device, thereby effectively ensuring the reliability of the diaphragm.

[0097] According to one embodiment of the present application, the room temperature storage modulus of the modified styrene butadiene rubber film layer is 0.4 MPa to 37 MPa. In some specific embodiments of the present application, the hardness of the modified styrene butadiene rubber film layer is 35A to 80A.

[0098] It should be noted that the sound-producing device can be a loudspeaker. The loudspeaker includes a vibration system and a magnetic circuit system that cooperates with the vibration system. The vibration system includes the diaphragm provided in this application, which can be a ring-shaped diaphragm or a flat diaphragm. Loudspeakers with the diaphragm provided in this application have advantages such as good sound quality and durability.

[0099] In some specific embodiments of the present application, the hardness of the modified styrene-butadiene rubber membrane layer can be 40A~75A, and the storage modulus at room temperature is 0.5MPa~35MPa, which enables the F0 of the speaker to reach 500Hz~1500Hz, and the low-frequency performance of the speaker is excellent.

[0100] In some specific embodiments of the present application, the loss factor of the modified styrene-butadiene rubber film layer at room temperature is greater than 0.12, preferably, the loss factor is greater than 0.14. The surface-modified inorganic hollow microspheres can be evenly dispersed in the SBR rubber matrix, and the amount of addition has little effect on the excellent damping properties of the rubber itself. Its damping value is greater than 0.12, preferably, the damping value is greater than 0.14, and the prepared diaphragm has a lower impedance curve. The speaker diaphragm has excellent damping performance, can effectively suppress the transient distortion of the speaker, can achieve high fidelity of the speaker electrical signal, and has good consistency of the vibration system.

[0101] Figure 3 This is a test curve showing the vibration displacement at different frequencies at different locations on the diaphragm according to an embodiment of the present application. The horizontal axis represents frequency (Hz), and the vertical axis represents loudness displacement (mm). Tests were performed at the edge and center of the diaphragm.

[0102] Figure 3 The various curves in the figure are concentratedly distributed, indicating that the vibration consistency of the various parts of the diaphragm of the embodiment of the present application is good. During the vibration process, the diaphragm has less polarized vibration and excellent sound quality.

[0103] According to one embodiment of the present application, the glass transition temperature of the modified styrene-butadiene rubber membrane layer is ≤-15°C, preferably ≤-17°C. A lower glass transition temperature enables the diaphragm to maintain good rubber elasticity in a low-temperature environment, so that the speaker exhibits a more comfortable listening experience. At the same time, it reduces the risk of damage to the speaker diaphragm in a low-temperature environment, and has higher reliability. In addition, the lower glass transition temperature enables the material to ensure excellent elasticity and maintain modulus consistency when working above the glass transition temperature. The F0 (resonance frequency) of the diaphragm prepared from this diaphragm material has better stability in the entire temperature range.

[0104] According to some embodiments of the present application, the diaphragm is formed as a single-layer structure, and the diaphragm is composed of a layer of modified styrene-butadiene rubber membrane.

[0105] According to some embodiments of the present application, the diaphragm is formed into a composite layer structure, further comprising a membrane layer made of at least one of a thermoplastic elastomer, an engineering plastic, and a thermosetting elastomer. Specifically, when the diaphragm is a composite diaphragm, it may include a single modified styrene-butadiene rubber membrane layer or multiple modified styrene-butadiene rubber membrane layers. The multiple modified styrene-butadiene rubber membrane layers may be arranged adjacent to each other or spaced apart. The specific arrangement method can be selected based on the specific design requirements of the sound-generating device.

[0106] Among them, the thermoplastic elastomer is at least one of thermoplastic polyester elastomer, thermoplastic polyurethane elastomer, thermoplastic polyamide elastomer and silicone elastomer, the engineering plastic is at least one of polyetheretherketone, polyarylate, polyetherimide, polyimide, polyphenylene sulfide, polyethylene naphthalate, polyethylene terephthalate and polybutylene terephthalate; the thermosetting elastomer is at least one of natural rubber, styrene-butadiene rubber, butadiene rubber, isoprene rubber, chloroprene rubber, butyl rubber, nitrile rubber, chlorinated nitrile rubber, ethylene-propylene rubber, silicone rubber, fluorosilicone rubber, fluororubber, polyurethane rubber, acrylate rubber, ethylene-acrylate rubber, ethylene-vinyl acetate rubber, chlorosulfonated polyethylene rubber, chloroether rubber and polysulfide rubber.

[0107] In other words, when the diaphragm is a composite diaphragm, it is composed of a film layer made of at least one of a thermoplastic polyester elastomer, a thermoplastic polyurethane elastomer, a thermoplastic polyamide elastomer, and a silicone elastomer, and a modified styrene-butadiene rubber film layer. The raw materials for the plastic polyurethane elastomer, thermoplastic polyamide elastomer, and silicone elastomer can be selected from a variety of sources and can be selected based on specific needs. The composite diaphragm, composed of a film layer made of a plastic polyurethane elastomer, a thermoplastic polyamide elastomer, and a silicone elastomer, and a modified styrene-butadiene rubber film layer, exhibits excellent mechanical properties, maintaining a certain level of mechanical strength while also possessing a high damping value.

[0108] In summary, the diaphragm of the sound-emitting device according to the embodiment of the present application is prepared by adopting a modified styrene-butadiene rubber membrane layer as raw material. It not only has excellent damping performance and rebound resilience, but the vibration system can effectively suppress the polarization phenomenon during the vibration sound-emitting process, and the consistency of the vibration system is better, which effectively reduces the distortion of the sound-emitting device. Moreover, by controlling the amount of inorganic hollow microbeads added, the density of the diaphragm is reduced, and the diaphragm has excellent aging resistance and mucous membrane resistance, thereby improving the mid-frequency performance and usage performance of the sound-emitting device.

[0109] It should be noted that the diaphragm provided herein can be incorporated into any sound-generating device, such as the following typical sound-generating device: It includes a vibration system and a magnetic circuit system that cooperates with the vibration system. The vibration system includes a diaphragm and a voice coil coupled to one side of the diaphragm. When the sound-generating device is in operation, the voice coil is energized and, under the influence of the magnetic field of the magnetic circuit system, vibrates up and down, driving the diaphragm to vibrate. This vibration of the diaphragm produces sound.

[0110] According to an embodiment of the second aspect of the present application, a sound-producing 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, thereby driving the diaphragm to produce sound. The diaphragm is the diaphragm of the aforementioned embodiment. Specifically, when the sound-producing device is in operation, after power is applied to the voice coil, the magnetic force of the magnetic circuit system causes the voice coil to vibrate up and down, driving the diaphragm to vibrate. The vibration of the diaphragm produces sound.

[0111] like Figure 4 and Figure 5 As shown, the sound-generating device includes a diaphragm 15 prepared according to an embodiment of the present application. The diaphragm 15 can be composed of a rim portion 151 and a dome portion 152. A modified styrene-butadiene rubber membrane layer can be applied to the rim portion 151 of the diaphragm. Those skilled in the art can make corresponding adjustments based on actual product requirements, such as increasing the rim portion 151 toward the voice coil 11, positioning the dome portion 152 on the lower surface of the rim portion 151, and adding a centering support to the vibration system.

[0112] According to the sound-generating device 100 of the third embodiment of the present application, Figure 6 and Figure 7 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 sound. The two ends of the second diaphragm 13 are respectively connected to the bottom of the shell 10 and the voice coil 11. The second diaphragm 13 is the diaphragm of the above embodiment.

[0113] That is, the sound-generating device 100 according to the embodiment of the present application may further include two diaphragms prepared according to the embodiment of the present application, namely, a first diaphragm 12 and a second diaphragm 13. The first diaphragm 12 can be used to vibrate and produce sound, and the second diaphragm 13 can be used to balance the vibration of the voice coil 11. Specifically, when the sound-generating device 100 is in operation, after the voice coil 11 is energized, the magnetic field force of the magnetic circuit system 14 causes the voice coil 11 to vibrate up and down, thereby driving the first diaphragm 12 to vibrate. When the first diaphragm 12 vibrates, sound can be produced. The second diaphragm 13 can also vibrate up and down following the voice coil 11. Since the two ends of the second diaphragm 13 are respectively connected to the housing 10 and the bottom of the voice coil 11, the second diaphragm 13 can balance the vibration of the voice coil 11, prevent polarization of the voice coil 11, and thus improve the sound quality of the sound-generating device 100.

[0114] It should be noted that the first diaphragm 12 and the second diaphragm 13 can both adopt the diaphragms of the embodiment of the present application, or one of the first diaphragm 12 or the second diaphragm 13 can adopt the diaphragm of the embodiment of the present application. The present application does not impose any specific restrictions on this.

[0115] The diaphragm of the sound-generating device of the present application is described in detail below with reference to specific embodiments.

[0116] The inorganic hollow microspheres herein are hollow glass microspheres. It should be noted that hollow glass microspheres are a type of inorganic hollow microspheres. The use of hollow glass microspheres or other inorganic hollow microspheres can also reflect the role played by inorganic hollow microspheres in the material.

[0117] Example 1

[0118] The formula, calculated by mass, is shown in Table 5. After mixing according to the formula, a cross-linking reaction is performed to form the diaphragm material. The diameter of the hollow glass microspheres is 60 μm to 70 μm.

[0119] Table 5

[0120]

[0121]

[0122] Comparative Example 1

[0123] The formula is shown in Table 6 in parts by mass. After mixing according to the formula, a cross-linking reaction is performed to form a diaphragm material.

[0124] Table 6

[0125]

[0126] First, SBR raw rubber, filler, and hollow glass microspheres were weighed as described in Example 1 and mixed in an internal mixer to produce an SBR rubber mix. The SBR rubber mix was then vulcanized using a plate vulcanizer to produce a 100 mm × 60 mm × 0.3 mm vulcanized sheet. The vulcanization conditions were: temperature 150°C, time 20 min, and pressure 12 MPa. DMA stress relaxation tests and loss factor tests were performed on Example 1 and Comparative Example 1.

[0127] Stress relaxation tests were performed according to ASTM D5026-15, using a tensile fixture, a test temperature of 23°C, a strain of 10%, and a relaxation time of 5 min. Three samples were tested for each set of data, and the test condition was 10% strain. The average value of the three samples was taken.

[0128] The loss factor test was conducted according to ASTM D5026-15, using a tensile fixture, with a test temperature range of -80°C to 200°C, a heating rate of 3°C / min, and a strain of 0.2%. The test results are as follows:

[0129] Table 7

[0130]

[0131] It can be seen from Table 7 that the strain recovery ratio and loss factor of the diaphragm material of the embodiment of this application are greater than those of the conventional SBR rubber diaphragm material, and the density and elongation at break are less than those of the conventional SBR rubber.

[0132] That is to say, after the inorganic hollow microspheres are mixed with rubber, they will be evenly dispersed inside the rubber. The inorganic hollow microspheres can reduce the density of the diaphragm, and the rubber molecules on the surface of the inorganic hollow microspheres are more likely to slide, so that the diaphragm has good resilience, ensuring the use effect of the diaphragm and the acoustic performance of the sound-generating device.

[0133] Although some specific embodiments of the present application have been described in detail by way of examples, it should be understood by those skilled in the art that the above examples are for illustration only and are not intended to limit the scope of the present application. It should be understood by those skilled in the art that the above embodiments may be modified without departing from the scope and spirit of the present application. The scope of the present application is defined by the appended claims.

Claims

1. A diaphragm of a sound-generating device, characterized in that: The diaphragm comprises at least one modified styrene-butadiene rubber membrane layer, which is prepared by mixing inorganic hollow microspheres, additives and polystyrene-butadiene copolymer 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 styrene-butadiene rubber film layer is 0.15 g / cm 3 ~0.9g / cm 3 The modified styrene-butadiene rubber film layer has a strain recovery ratio of ≥70% after relaxation for 5 minutes at 23° C. and a strain of 10%, and the content of the inorganic hollow microspheres accounts for 5wt% to 50wt% of the total amount of the mixed rubber.

2. The diaphragm of the sound-generating device according to claim 1, wherein: The compressive strength of the inorganic hollow microspheres is ≥10 MPa.

3. The diaphragm of the sound-generating device according to claim 1, wherein: The glass transition temperature of the modified styrene-butadiene rubber film layer is ≤-15°C.

4. The diaphragm of the sound-generating device according to claim 1, wherein: The surface energy of the modified styrene-butadiene rubber film layer is ≤58 J / m 2 .

5. The diaphragm of the sound-generating device according to claim 1, wherein: After the modified styrene-butadiene rubber film layer is aged in hot air at 150° C. for 16 hours, the tensile strength of the modified styrene-butadiene rubber film layer decreases by ≤50%, and the elongation at break decreases by ≤70%.

6. The diaphragm of the sound-generating device according to claim 1, characterized in that: The additives include a cross-linking agent, a reinforcing agent and an antioxidant; The cross-linking agent is at least one of sulfur, phenolic resin and organic peroxide; the reinforcing agent is at least one of carbon black, white carbon black, calcium carbonate and nano titanium dioxide; and 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, characterized in that: The content of the cross-linking agent accounts for 0.5wt% to 5wt% of the rubber mix, the content of the reinforcing agent accounts for 5wt% to 70wt% of the rubber mix, and the content of the antioxidant accounts for 0.1wt% to 6wt% of the rubber mix.

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

12.

9. The diaphragm of the sound-generating device according to claim 1, characterized in that: The density of the modified styrene-butadiene rubber film layer is 0.4 g / cm 3 ~1.1g / cm 3 .

10. The diaphragm of the sound-generating device according to claim 1, wherein: The diaphragm is a single-layer structure, and the diaphragm is composed of a layer of modified styrene-butadiene rubber membrane.

11. The diaphragm of the sound-generating device according to claim 1, wherein: The diaphragm is a composite layer structure, and the diaphragm further comprises a membrane layer made of at least one of thermoplastic elastomer, engineering plastic and thermosetting elastomer.

12. A sound-generating device, characterized in that: It includes a vibration system and a magnetic circuit system coordinated with the vibration system, the vibration system includes a diaphragm and a voice coil coupled to one side of the diaphragm, the magnetic circuit system drives the voice coil to vibrate to drive the diaphragm to make sound, and the diaphragm is the diaphragm described in any one of claims 1-11.

13. A sound-generating device, characterized in that: It includes a shell and a magnetic circuit system and a vibration system arranged in the shell, the vibration system includes a voice coil, a first diaphragm and a second diaphragm, the top of the voice coil is connected to the first diaphragm, the magnetic circuit system drives the voice coil to vibrate to drive the first diaphragm to make sound, the two ends of the second diaphragm are respectively connected to the shell and the bottom of the voice coil, and the second diaphragm is the diaphragm according to any one of claims 1 to 11.

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