Rubber diaphragm and sound-producing device

Abstract

The present application provides a rubber diaphragm and a sound-producing device. The diaphragm is prepared from a polymer matrix and auxiliary agents by means of a vulcanization and cross-linking reaction. The auxiliary agents comprise a filler, a vulcanizing agent, an accelerator, a plasticizer, and an activator. In parts by weight, the addition amounts of the polymer matrix and the auxiliary agents are respectively as follows: 100 parts of the polymer matrix, 40-120 parts of the filler, 1-4 parts of the vulcanizing agent, 2-5 parts of the accelerator, 5-20 parts of the plasticizer, and 0.5-1.5 parts of the activator. The rubber diaphragm of the present application is prepared from the polymer matrix and the auxiliary agents by means of a vulcanization and cross-linking reaction. By coordinating the choices of polymer matrix types and auxiliary agents with the addition amounts of the raw materials, the diaphragm is prepared. The glass transition temperature Tg (DMA, 1 Hz, 3 K / min) of the resulting diaphragm is between -20ºC and -40ºC, a ratio of the modulus thereof at a low temperature of -20ºC to that at a normal temperature of 25ºC is less than 4.5, and various performance indicators are stable in a low-temperature environment, ensuring that a sound-producing device made of the diaphragm has stable performance in a low-temperature environment.

Description

Rubber diaphragm and sound emitting device TECHNICAL FIELD

[0001] The present application relates to the technical field of electro-acoustic conversion, in particular to a rubber diaphragm and a sound emitting device. BACKGROUND

[0002] The rubber diaphragm material in the prior art is generally prepared by using thermoplastic elastomers such as thermoplastic polyester elastomer (TPEE for short), thermoplastic polyurethane elastomer rubber (TPU for short), or thermosetting elastomers such as nitrile rubber and acrylate rubber as raw materials. The rubber diaphragm obtained in the prior art has poor low-temperature resistance. In a low-temperature environment (for example, the outdoor temperature in northern regions can be as low as-25°C or below), the elastic modulus of the diaphragm increases greatly, which reduces the Cms (Cms is the force order, which refers to the mechanical compliance of the support part of the loudspeaker vibration system) of the acoustic device vibration system, increases the F0 (F0 is the lowest resonance frequency, which refers to the frequency corresponding to the first maximum value of the loudspeaker impedance curve), and sharply decreases the sensitivity. The product stability decreases, and the application environment is greatly limited.

[0003] Therefore, it is necessary to provide a rubber diaphragm and a sound emitting device with good low-temperature resistance.

[0004] SUMMARY

[0005] The present application aims to solve the above problems and provide a rubber diaphragm and a sound emitting device.

[0006] The technical solution of the present application is as follows:

[0007] In a first aspect, the present application provides a rubber diaphragm, which is prepared by vulcanization cross-linking reaction of a polymer matrix and an additive.

[0008] The polymer matrix is ethylene acrylate rubber, and its structural formula is as follows:

[0009] wherein R and R' independently represent one of methyl, ethyl or n-butyl; a, b, c are positive integers.

[0010] The additive includes a filler, a vulcanizing agent, an accelerator, a plasticizer and an activator. The additive amount of the polymer matrix and the additive is 100 parts of the polymer matrix, 40-120 parts of the filler, 1-4 parts of the vulcanizing agent, 2-5 parts of the accelerator, 5-20 parts of the plasticizer and 0.5-1.5 parts of the activator, in terms of weight fraction.

[0011] Optionally, the ratio of the ethylene segment and the acrylate segment in the polymer matrix is between 1 and 8, and the ratio of n-butyl in the side groups R and / or R' is 10-30%.

[0012] Optionally, the plasticizer comprises one or more of phthalic acid plasticizers, aliphatic dibasic acid ester plasticizers, polyester plasticizers or ether ester plasticizers.

[0013] Optionally, the vulcanizing agent comprises one or more of peroxide vulcanizing agents, isocyanate vulcanizing agents, epoxy vulcanizing agents, amine vulcanizing agents or aziridine vulcanizing agents.

[0014] Optionally, the accelerator comprises one or more of amine accelerators, thiazole accelerators, thiuram accelerators, diphenyl guanidine accelerators, dithiocarbamate accelerators and thiourea accelerators.

[0015] Optionally, the activator comprises one or more of stearic acid or fatty acids and derivatives thereof.

[0016] Optionally, the auxiliary agent further comprises 0.5-3 parts of a coupling agent, 1-3 parts of an anti-aging agent and 1-5 parts of a release agent, based on 100 parts of the polymer matrix.

[0017] In a second aspect, the present application provides a sound production device, comprising a frame, a vibration system and a magnetic circuit system accommodated in the frame, the vibration system comprising a middle diaphragm, an upper diaphragm and a lower diaphragm, at least one of the middle diaphragm, the upper diaphragm and the lower diaphragm being prepared by using the rubber diaphragm as described above.

[0018] The rubber diaphragm described in the present application is prepared by vulcanization cross-linking reaction of a polymer matrix and an auxiliary agent; wherein the polymer matrix is a low-temperature ethylene propylene acrylate rubber, the auxiliary agent comprises fillers, vulcanizing agents, accelerators, plasticizers and activators, the rubber diaphragm is prepared by the joint matching of the polymer matrix type and the auxiliary agent and the addition amount of raw materials, the glass transition temperature Tg(DMA, 1 Hz, 3 K / min) of the obtained rubber diaphragm is between -20 and -40℃, the high and low temperature modulus change rate at low temperature -20℃ and normal temperature 25℃ is less than 4.5, compared with the rubber diaphragm material in the prior art, the various performance indicators are stable in a low temperature environment, thereby ensuring that the sound production device made of the rubber diaphragm obtained by the present application has stable performance in a low temperature environment. BRIEF DESCRIPTION OF DRAWINGS

[0019] Figure 1 is a dynamic mechanical analysis test curve graph of a rubber diaphragm before and after high temperature reliability using a conventional plasticizer.

[0020] Figure 2 is a dynamic mechanical analysis test curve graph of a rubber diaphragm before and after high temperature reliability using the plasticizer of the present application.

[0021] Fig. 3 is a dynamic mechanical analysis test curve of the diaphragm of the present application and the diaphragm of Comparative Example 1.

[0022] Fig. 4 is a frequency response curve of the diaphragm of the present application and the diaphragm of Comparative Example 1 applied to a sound production device.

[0023] Fig. 5 is a structural schematic diagram of a sound production device of an embodiment of the present application.

[0024] Fig. 6 is an exploded schematic diagram of a sound production device of an embodiment of the present application. DETAILED DESCRIPTION

[0025] The present application will be further described below in conjunction with the drawings and embodiments.

[0026] In a first aspect, an embodiment of the present application provides a rubber diaphragm, which is prepared by a vulcanization cross-linking reaction of a polymer matrix and an auxiliary agent.

[0027] The polymer matrix is an ethylene acrylate rubber, and its structural formula is:

[0028] wherein R and R' independently represent one of methyl, ethyl or n-butyl; a, b, c are positive integers.

[0029] The auxiliary agent includes a filler, a vulcanizing agent, an accelerator, a plasticizer and an activator; the additive amounts of the polymer matrix and the auxiliary agent are 100 parts of the polymer matrix, 40-120 parts of the filler, 1-4 parts of the vulcanizing agent, 2-5 parts of the accelerator, 5-20 parts of the plasticizer and 0.5-1.5 parts of the activator, by weight.

[0030] Optionally, the rubber diaphragm obtained by the present application can be applied to a micro sound production device.

[0031] The rubber diaphragm of the present application is prepared by a vulcanization cross-linking reaction of a polymer matrix and an auxiliary agent; wherein the polymer matrix is a low-temperature ethylene acrylate rubber, and the auxiliary agent includes a filler, a vulcanizing agent, an accelerator, a plasticizer and an activator. The rubber diaphragm is prepared by the joint matching of the polymer matrix type and the auxiliary agent and the additive amounts of raw materials. The glass transition temperature Tg(DMA, 1 Hz, 3 K / min) of the obtained rubber diaphragm is between -20 and -40℃, and the high and low temperature modulus change rate at low temperature -20℃ and normal temperature 25℃ is less than 4.5. Compared with the diaphragm materials in the prior art, the various performance indicators of the rubber diaphragm of the present application are stable at low temperature, thereby ensuring that the sound production device made of the rubber diaphragm of the present application has stable performance in a low temperature environment.

[0032] Optionally, the ratio of ethylene segments and acrylate segments in the polymer matrix is between 1 and 8, and the ratio of n-butyl groups in the side groups R and / or R' is 10-30%.

[0033] For ethylene acrylate rubber, firstly, the ratio of ethylene segments in the molecular chain is a key factor directly affecting the low-temperature characteristics of the rubber, and the higher the ratio of ethylene segments, the better the low-temperature characteristics; secondly, the length of the acrylate side groups also affects the low-temperature characteristics of the rubber to some extent, and the longer the side groups, the better the flexibility of the molecular chain and the better the low-temperature characteristics. Therefore, based on the comprehensive consideration of low-temperature resistance and hardness requirements, the ratio of ethylene segments and acrylate segments in the polymer matrix is between 1 and 8, and the ratio of n-butyl groups in the side groups R and / or R' is 10-30%.

[0034] Optionally, the plasticizer includes one or more of phthalic acid plasticizers, aliphatic dibasic acid ester plasticizers, polyester plasticizers, or ether ester plasticizers.

[0035] Optionally, the plasticizer is a mixed ether ester plasticizer. The mixed ether ester plasticizer can be obtained from a supplier known in the art or prepared by a known method.

[0036] The mixed ether ester plasticizer selected in the application has a small polar or partially polar molecule in structure. It can be uniformly distributed between the high molecular chains, reduce the intermolecular force, reduce the viscosity of the high molecular material, and enhance the flexibility of the molecular chain, thereby reducing the glass transition temperature of the material and improving the low-temperature characteristics. In the application, the mixed ether ester plasticizer is used as a single variable to prepare a diaphragm, and the glass transition temperature and E'(-20℃) / E'(25℃) of the obtained diaphragm are measured; wherein E'(-20℃) represents the storage modulus of the diaphragm in a low-temperature environment of-20℃, E'(25℃) represents the storage modulus of the diaphragm in a normal temperature environment of 25℃, and the ratio of the two can indirectly reflect the change of the diaphragm in low temperature and normal temperature, and the smaller the ratio, the better the low-temperature resistance. Table 1 is a corresponding relationship table of the addition amount of the plasticizer in the diaphragm of the application and the transition temperature and E'(-20℃) / E'(25℃) of the diaphragm; the glass transition temperature Tg(DMA, 1Hz, 3K / min) of the obtained diaphragm is between-20 and-40℃, and the high-low temperature modulus change ratio of the diaphragm at low temperature-20℃ and normal temperature 25℃ is less than 4.5.

[0037] Table 1:

[0038] In actual use, the temperature of the diaphragm area of the sound generating device can reach 130℃ when working for a long time or when being connected to a high temperature experiment, and the instantaneous temperature of some products can reach 150℃. Therefore, the high temperature resistance of the diaphragm is also very important for the stability of the sound generating device. The diaphragm prepared by using the conventional plasticizer in the prior art and the diaphragm prepared by using the mixed ether ester plasticizer in the present application were subjected to high temperature reliability test. FIG. 1 is the DMA damping curve of the diaphragm prepared by using the conventional plasticizer in the prior art before and after high temperature reliability test (the temperature corresponding to the peak is the glass transition temperature), and FIG. 2 is the DMA damping curve of the diaphragm prepared by using the mixed ether ester plasticizer in the present application before and after high temperature reliability test (the temperature corresponding to the peak is the glass transition temperature). As shown in FIG. 1 and FIG. 2, the glass transition temperature of the diaphragm prepared by using the mixed ether ester plasticizer in the present application before and after high temperature reliability test fluctuates less. The reason is that the plasticizer in the diaphragm of the sound generating device prepared by using the conventional plasticizer in the prior art will volatilize when working for a long time or in a high temperature environment, which will cause the low temperature characteristics of the diaphragm to be seriously damaged, and will also cause the hardness of the diaphragm to increase, the F0 of the sound generating device to increase, the SPL to decrease, and the stability of the product to decrease. The diaphragm obtained in the present application not only has good low temperature resistance, but also has high temperature resistance up to 180℃. When applied to the diaphragm of the sound generating device, the diaphragm is not easy to volatilize, the glass transition temperature of the diaphragm changes only by 3℃ before and after the high temperature experiment, and the performance of the sound generating device such as F0 and SPL does not change significantly, and the product has good stability.

[0039] Optionally, the filler includes one or more of carbon black, white carbon black, talc powder, quartz powder, hydrotalcite, calcium carbonate, silica, diatomite, nano clay or montmorillonite.

[0040] Taking the talc powder filler as an example, the glass transition temperature and E'(-20℃) / E'(25℃) of the diaphragm obtained by adding the filler in the present application were determined. E'(-20℃) represents the storage modulus of the diaphragm in a low temperature environment of-20℃, and E'(25℃) represents the storage modulus of the diaphragm in a normal temperature environment of 25℃. The ratio of the two can indirectly reflect the change of the diaphragm in low temperature and normal temperature. The smaller the ratio, the better the low temperature resistance. Table 2 is a correspondence table of the content, the glass transition temperature of the diaphragm and E'(-20℃) / E'(25℃) in the present application. As shown in Table 2, the contact area between the rubber molecular chain and the filler increases, and the internal friction also increases when the amount of the filler increases, which will further limit the movement of the molecular chain, and the flexibility and elasticity of the molecular chain will be worse, the glass transition temperature will increase, and the low temperature characteristics will decrease. The glass transition temperature Tg(DMA, 1Hz, 3K / min) of the diaphragm obtained in the preferred amount in the present application is between-20 and-40℃, and the high and low temperature modulus change rate at low temperature-20℃ and normal temperature 25℃ is less than 4.5.

[0041] Table 2:

[0042] Optionally, the vulcanizing agent comprises one or more of peroxide vulcanizing agent, isocyanate vulcanizing agent, epoxy vulcanizing agent, amine vulcanizing agent or aziridine vulcanizing agent.

[0043] Optionally, the accelerator comprises one or more of amine accelerator, thiazole accelerator, thiuram accelerator, diphenyl guanidine accelerator, dithiocarbamate accelerator and thiourea accelerator.

[0044] Optionally, the activator comprises one or more of stearic acid or fatty acid and its derivatives.

[0045] Optionally, the auxiliary agent further comprises 0.5-3 parts of coupling agent, 1-3 parts of antioxidant and 1-5 parts of release agent, based on 100 parts of the polymer matrix.

[0046] Optionally, the coupling agent comprises one or more of silane coupling agent with model number KH550, KH-560 or KH-570 or phthalate coupling agent with model number NDZ-101, NDZ-201, NDZ-311.

[0047] Optionally, the antioxidant comprises one or more of antioxidant 264, antioxidant 2246, antioxidant MB, antioxidant MBZ, antioxidant SP or antioxidant 445.

[0048] Optionally, the release agent comprises one or more of polyethylene wax, paraffin wax, ethylene bis-stearamide, oleic acid amide, erucic acid amide, phosphate ester or high molecular fatty acid ester.

[0049] In a second aspect, the present application provides a sound production device, as shown in FIG. 5 and FIG. 6, which comprises a frame 1, a vibration system 2 and a magnetic circuit system 3 accommodated in the frame 1, the vibration system 2 comprises a middle diaphragm 21, an upper diaphragm 22 and a lower diaphragm 23, at least one of the middle diaphragm 21, the upper diaphragm 22 and the lower diaphragm 23 is prepared by using the rubber diaphragm as described above.

[0050] Optionally, the sound production device is a micro sound production device.

[0051] The magnetic circuit system 3 comprises upper and lower clamping plates 31 and 32 arranged in parallel, an inner magnetic steel 33, a pole core 34 and an outer magnetic steel 35 arranged on the lower clamping plate 32, and an edge magnetic steel 36 arranged circumferentially along the inner magnetic steel 33; the inner magnetic steel 33 and the edge magnetic steel 36 have a magnetic gap therebetween, and the inner magnetic steel 33, the pole core 34 and the outer magnetic steel 35 are sequentially arranged on the lower clamping plate 32 from bottom to top.

[0052] The vibration system 2 further comprises a skeleton 24, a flexible circuit board 25 and a voice coil 26, the middle diaphragm 21 is arranged above the outer magnetic steel 35, the skeleton 24 is arranged at the outer periphery of the middle diaphragm 21, the upper diaphragm 22 is arranged at the outer periphery of the skeleton 24, the voice coil 26 is arranged in the magnetic gap, the lower diaphragm 23 is arranged below the upper diaphragm 22, the flexible circuit board 25 is arranged below the lower diaphragm 23 and in conductive communication with the voice coil 26, and the skeleton 24 is connected to the flexible circuit board 25 to support the vibration system 2 on the flexible circuit board 25.

[0053] In the embodiment, the diaphragm formula comprises 100 parts of low-temperature ethylene propylene rubber (hereinafter referred to as low-temperature AEM raw rubber), 80 parts of filler, 2 parts of vulcanizing agent, 3 parts of accelerator, 1 part of activator and 5 parts of mixed ether ester plasticizer, wherein the filler is talc, the vulcanizing agent is hexanediamine, the accelerator is tertiary amine and the activator is stearic acid.

[0054] In the embodiment, the diaphragm formula comprises 100 parts of low-temperature AEM raw rubber, 100 parts of filler, 2 parts of vulcanizing agent, 3 parts of accelerator, 1 part of activator and 10 parts of mixed ether ester plasticizer, wherein the filler is talc, the vulcanizing agent is hexanediamine, the accelerator is tertiary amine and the activator is stearic acid.

[0055] In the comparative example, the diaphragm formula comprises 100 parts of conventional AEM raw rubber, 40 parts of filler, 2 parts of vulcanizing agent, 3 parts of accelerator and 1 part of activator, wherein the filler is talc, the vulcanizing agent is hexanediamine, the accelerator is tertiary amine and the activator is stearic acid.

[0056] Test example: the diaphragm prepared by example 2, example 3 and comparative example 1 is respectively subjected to dynamic mechanical analysis test, and figure 3 is a dynamic mechanical analysis test curve diagram of the diaphragm of the present application and the diaphragm of comparative example 1, as shown in figure 3, compared with comparative example 1, the diaphragm obtained by the present application has a smaller ratio of storage modulus in a low temperature environment of-20℃ to storage modulus in a normal temperature environment of 25℃, E'(-20℃) / E'(25℃), than the diaphragm of the prior art in dynamic mechanical analysis (Dynamic mechanical analysis, DMA), indicating that the diaphragm of the present application has good low temperature resistance.

[0057] The diaphragm prepared by example 2, example 3 and comparative example 1 is applied to a sound generating device, and the sound generating device is subjected to frequency response test, and figure 4 is a frequency response curve diagram of the diaphragm of the present application and the diaphragm of comparative example 1 applied to the sound generating device, as shown in figure 4, compared with comparative example 1, the frequency response value of the diaphragm of the present application applied to the sound generating device changes less under the conditions of normal temperature and low temperature, indicating that the diaphragm of the present application has good low temperature resistance.

[0058] In addition, the SPL (Sound Pressure Level, i.e. sound pressure level) of the diaphragm obtained by the present application applied to the sound generating device changes less than 2dB under the condition of-20℃ low temperature compared with normal temperature.

[0059] The above is only an embodiment of the present application, and it should be pointed out here that for those skilled in the art, improvements can be made without departing from the creative concept of the present application, but these all belong to the protection scope of the present application.

Claims

1. A rubber diaphragm characterized by, The rubber diaphragm is prepared by vulcanization cross-linking reaction of a polymer matrix and an auxiliary agent. The polymer matrix is ethylene acrylate rubber, and its structural formula is: wherein R and R' independently represent one of methyl, ethyl or n-butyl; a, b, c are positive integers. The auxiliary agent includes fillers, vulcanizing agents, accelerators, plasticizers and activators; the polymer matrix and the auxiliary agent are added in the following amounts: 100 parts of the polymer matrix, 40-120 parts of the fillers, 1-4 parts of the vulcanizing agents, 2-5 parts of the accelerators, 5-20 parts of the plasticizers and 0.5-1.5 parts of the activators.

2. The rubber diaphragm of claim 1, wherein The ratio of ethylene segments and acrylate segments in the polymer matrix is between 1 and 8, and the ratio of n-butyl in the side groups R and / or R' is 10-30%.

3. The rubber diaphragm of claim 1, wherein, The plasticizer includes one or more of phthalic acid plasticizers, aliphatic dibasic acid ester plasticizers, polyester plasticizers or ether ester plasticizers.

4. The rubber diaphragm of claim 1, wherein The plasticizer is a mixed ether ester plasticizer.

5. The rubber diaphragm of claim 1, wherein The fillers include one or more of carbon black, white carbon black, talc powder, quartz powder, hydrotalcite, calcium carbonate, silica, diatomite, nano clay or montmorillonite.

6. The rubber diaphragm of claim 1, wherein The vulcanizing agent includes one or more of peroxide vulcanizing agents, isocyanate vulcanizing agents, epoxy vulcanizing agents, amine vulcanizing agents or aziridine vulcanizing agents.

7. The rubber diaphragm of claim 1, wherein The accelerator includes one or more of amine accelerators, thiazole accelerators, thiuram accelerators, diphenyl guanidine accelerators, dithiocarbamate accelerators and thiourea accelerators.

8. The rubber diaphragm of claim 1, wherein, The activator includes one or more of stearic acid or fatty acids and their derivatives.

9. The rubber diaphragm of claim 1, wherein, The auxiliary agent further includes 0.5-3 parts of a coupling agent, 1-3 parts of an anti-aging agent and 1-5 parts of a release agent, based on 100 parts of the polymer matrix.

10. A sound producing device, characterized by The pot frame, the vibration system and the magnetic circuit system accommodated in the pot frame, at least one of the middle diaphragm, the upper diaphragm and the lower diaphragm is prepared by the rubber diaphragm according to any one of claims 1-9.

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