CN114071329A

CN114071329A - Sound generating device's vibrating diaphragm and sound generating device

Info

Publication number: CN114071329A
Application number: CN202111275656.0A
Authority: CN
Inventors: 王伟超; 王婷; 李春; 刘春发
Original assignee: Goertek Inc
Current assignee: Goertek Inc
Priority date: 2021-10-29
Filing date: 2021-10-29
Publication date: 2022-02-18

Abstract

The application discloses sound generating mechanism's vibrating diaphragm and sound generating mechanism, vibrating diaphragm contain mixed polyurethane rubber rete, mixed polyurethane rubber rete is mixed by polyurethane crude rubber, vulcanizer, vulcanization accelerator, filler, plasticizer, anti-oxidant and other auxiliaries and is formed: the addition amount of the polyurethane raw rubber is 100 parts by weight, the plasticizer is a polyester plasticizer, and the addition amount of the plasticizer is 0.5-10 parts by weight. This application is through using polyester type plasticizer to the quantity of strict control plasticizer can make the vibrating diaphragm have better anti swelling capacity to oleic acid, sun cream, grease etc. improves product acoustic performance, prolongs the life of product.

Description

Sound generating device's vibrating diaphragm and sound generating device

Technical Field

The application relates to the technical field of electroacoustic, more specifically relates to a sound generating mechanism's vibrating diaphragm and use sound generating mechanism of this vibrating diaphragm.

Background

The sound generating device of the existing wearable product earphone, intelligent watch, intelligent bracelet, VR and AR mostly adopts thermoplastic elastomer, and a small part of the sound generating device adopts rubber such as Nitrile Butadiene Rubber (NBR) to manufacture the vibrating diaphragm. In daily life, sunscreen cream, face cream and color cosmetics which are frequently used by people contain oil substances, and the human body can secrete oil. In the long-term use of wearing products, these cosmetics and body-secreted oils inevitably come into contact with the diaphragm. And the diaphragms made of thermoplastic polyurethane elastomer (TPU), polyester thermoplastic elastomer (TPEE) composite films, Hydrogenated Nitrile Butadiene Rubber (HNBR) and other materials have poor tolerance to the grease. The TPU vibrating diaphragm can slightly deform and swell after contacting with the grease substance containing oleic acid, and the TPEE composite membrane vibrating diaphragm and the HNBR vibrating diaphragm can absorb a large amount of grease in the grease substance and deform and swell, so that the acoustic performance of the vibrating diaphragm product is reduced, and the service life and the user experience of an electronic product are seriously influenced.

Disclosure of Invention

An aim at of this application provides a sound generating mechanism's vibrating diaphragm, can overcome present interior conventional thermoplastic elastomer and vibrating diaphragms such as HNBR poor to the anti swelling capacity of the grease class material that contains oleic acid, is comparatively sensitive to the chemicals, easily causes acoustics and the poor problem of reliability.

Another object of this application is to provide a sound generating mechanism that above-mentioned vibrating diaphragm is constituteed.

In order to achieve the above object, the present application provides the following technical solutions.

According to this application first aspect embodiment's sound generating mechanism's vibrating diaphragm, the vibrating diaphragm contains mixed polyurethane rubber rete, mixed polyurethane rubber rete is formed by polyurethane crude rubber, vulcanizer, vulcanization accelerator, filler, plasticizer, antioxidant and other auxiliaries are mixed: the addition amount of the polyurethane raw rubber is 100 parts by weight, the plasticizer is a polyester plasticizer, and the addition amount of the plasticizer is 0.5-10 parts by weight.

According to some embodiments of the present application, the mass change rate of the compounded polyurethane rubber film layer after being soaked in oleic acid at 65 ℃ for 96 hours is-5% to 5%.

According to some embodiments of the present application, the plasticizer has a number average molecular weight of 1000 to 5000.

According to some embodiments of the present application, the raw polyurethane rubber comprises a hard segment and a soft segment, wherein the hard segment is selected from one or more of toluene diisocyanate, diphenylmethane diisocyanate, 1, 5-naphthalene diisocyanate, p-phenylene diisocyanate, and dimethylbiphenyl diisocyanate, and the soft segment is at least one of polyester polyol, polycarbonate polyol, and polycaprolactone polyol.

According to some embodiments of the present application, the vulcanizing agent is added in an amount of 0.1 to 10 parts by mass, and the vulcanizing agent is selected from one or more of dicumyl peroxide, 1 di-tert-butylperoxy-3, 3, 5-trimethylcyclohexane, di-tert-butyl peroxide, 2, 5-dimethyl-2, 5 (di-tert-butylperoxy) hexane, di-tert-butylperoxyisopropyl benzene, benzoyl peroxide, 2, 4-dichlorobenzoyl peroxide, tert-butyl perbenzoate, and sulfur.

According to some embodiments of the present application, the vulcanization accelerator is added in an amount of 0.1 to 5 parts by mass, and the vulcanization accelerator is one or more of thiazoles, sulfenamides, thiurams, thioureas, dithiocarbamates, aldamines, xanthates, triallyl isocyanate, triallyl cyanurate, and N, N-m-methylene-bismaleimide.

According to some embodiments of the present application, the filler is added in an amount of 1 to 80 parts by mass, and the filler is one or more selected from carbon black, white carbon black, talc powder, calcium carbonate, magnesium carbonate, dolomite, barium sulfate, zinc sulfide, aluminum powder, graphite, titanium dioxide, lithopone, phenolic resin, petroleum resin, and styrene resin.

According to some embodiments of the present application, the amount of the antioxidant added is 0.5 to 5 parts by mass, and the antioxidant is selected from one or more of antioxidant 1010, antioxidant 2, antioxidant 6, antioxidant 4, antioxidant 1076, antioxidant 168, antioxidant RD, antioxidant AW, antioxidant DD, antioxidant BLE, antioxidant 4010, 4010NA, 4020, 4030, 4040, antioxidant DNP, antioxidant H, antioxidant A, antioxidant D, antioxidant SP, antioxidant 264, antioxidant 2246-S, antioxidant NBC, and antioxidant MB.

According to some embodiments of the present application, the other additives include at least one of an anti-hydrolysis additive, zinc oxide, stearic acid, an ultraviolet absorber, a color paste.

According to some embodiments of the present application, the thickness of the compounded urethane rubber film layer is 25 μm to 300 μm.

According to the sound generating mechanism of this application second aspect embodiment, including vibration system and with vibration system matched with magnetic circuit, vibration system includes the vibrating diaphragm and combines the voice coil loudspeaker voice coil of vibrating diaphragm one side, the magnetic circuit drive the voice coil loudspeaker voice coil vibration is in order to drive the vibrating diaphragm sound production, the vibrating diaphragm is according to this application above-mentioned embodiment the vibrating diaphragm.

According to this application third aspect embodiment's sound generating mechanism, include the casing and establish magnetic circuit and vibration system in the casing, vibration system includes voice coil loudspeaker voice coil, first vibrating diaphragm and second vibrating diaphragm, the top of voice coil loudspeaker voice coil with first vibrating diaphragm links to each other, the magnetic circuit drive the voice coil loudspeaker voice coil vibration is in order to drive first vibrating diaphragm sound production, the both ends of second vibrating diaphragm respectively with the casing with the bottom of voice coil loudspeaker voice coil links to each other, the second vibrating diaphragm is according to this application above-mentioned embodiment the vibrating diaphragm.

According to sound generating mechanism's vibrating diaphragm of this application embodiment, through using polyester type plasticizer to the quantity of strict control plasticizer can make the vibrating diaphragm have better anti swelling capacity to oleic acid, improves the acoustic performance stability of vibrating diaphragm, prolongs the life of vibrating diaphragm product.

Further features of the present application and advantages thereof will become apparent from the following detailed description of exemplary embodiments thereof, which is to be read in connection with the accompanying drawings.

Drawings

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.

Fig. 1 is a schematic overall structure diagram of a sound generating device according to an embodiment of the present application;

fig. 2 is a partial structural schematic diagram of a sound generating device according to an embodiment of the present application;

FIG. 3 is a cross-sectional view of a sound emitting device according to an embodiment of the present application;

fig. 4 is an exploded view of a sound emitting device according to an embodiment of the present application.

Reference numerals

A sound generating device 100;

a housing 10; a voice coil 11; a first diaphragm 12; a second diaphragm 13; a magnetic circuit system 14;

a diaphragm 15; a folded ring portion 151; a ball top 152.

Detailed Description

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

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

Techniques, methods, and apparatus known to those of ordinary skill in the relevant art may not be discussed in detail but are intended to be part of the specification where appropriate.

In all examples shown and discussed herein, any particular value should be construed as merely illustrative, and not limiting. Thus, other examples of the exemplary embodiments may have different values.

It should be noted that: like reference numbers and letters refer to like items in the following figures, and thus, once an item is defined in one figure, further discussion thereof is not required in subsequent figures.

The diaphragm of the sound generating apparatus according to the embodiment of the present application is described in detail below with reference to the drawings.

According to sound generating mechanism's of this application embodiment vibrating diaphragm, the vibrating diaphragm includes mixing polyurethane rubber rete. The mixed polyurethane rubber (MPU) is composed of polyether or polyester flexible chain segments and urethane rigid chain segments, and a cross-linked polymer formed by reaction with a vulcanizing machine can be modified by a mixing method to prepare a thermosetting elastomer with required performance.

The mixing type polyurethane rubber film layer is formed by mixing polyurethane raw rubber, a vulcanization accelerator, a vulcanizing agent, a filler, a plasticizer, an antioxidant and other auxiliaries. Namely, raw polyurethane rubber, a vulcanization accelerator, a vulcanizing agent, a filler, a plasticizer, an antioxidant and other auxiliaries are used as raw materials, and the mixing type polyurethane rubber film layer is prepared by a mixing method.

Wherein the addition amount of the polyurethane raw rubber is 100 parts by weight, the plasticizer is a polyester plasticizer, and the addition amount of the plasticizer is 0.5-10 parts by weight.

It is found that the amount and type of plasticizer significantly affects the chemical resistance stability of the MPU. The molecular weight of the plasticizer is generally lower, and the dispersion of materials such as fillers, vulcanizing agents and the like which are indispensable in rubber is difficult, for example, white carbon black or carbon black is easy to fly in the mixing process, if the white carbon black or the carbon black is not mixed with the plasticizer uniformly in advance, a large amount of loss is caused, the formula reproducibility is poor, and indoor dust pollution is also caused.

When the plasticizer is used in combination with rubber, intermolecular acting force of the rubber can be obviously reduced, the wetting capacity with the rubber, other additives and fillers is strong, and the heat generation phenomenon in the mixing process can be improved.

Meanwhile, the plasticizer can also increase the adhesive property, the processing plasticity and the fluidity of the rubber material, and provides convenience for the forming processes such as calendering, extrusion and the like.

And the presence of a plasticizer also improves the hardness of the matrix.

The hardness of the conventional MPU material after crosslinking is generally high and is difficult to be lower than 35A unless the MPU material is blended with a plasticizer. That is, in order to obtain MPU of low hardness, a plasticizer is an indispensable material, and at the same time, cold resistance of the material can be improved.

However, the existing plasticizers are various in types, and most plasticizers have low molecular weight and low bonding strength with a matrix. The product oleic acid, grease and sunscreen cream are easy to be extracted by the chemicals, so that the phenomena of quality reduction, hardness increase, resonant frequency (F0) increase and the like are caused.

Therefore, in this embodiment, a polyester plasticizer with a relatively large molecular weight and difficult precipitation is selected, and the amount of the plasticizer is strictly controlled, after the experiments of oleic acid, grease and sunscreen cream, the compounded polyurethane rubber film layer has good grease resistance, and F0 does not rise significantly, and still maintains good acoustic performance.

In this example, the amount of the plasticizer added was less than 10 parts by mass. Because even the polyester plasticizer having a large molecular weight is precipitated by the long-term action of oleic acid. When the plasticizer is used in an amount of more than 10 parts, the oleic acid is reliably recovered, the mass loss exceeds 5%, and the amount of change in F0 in the product is large.

Further, the preparation method of the diaphragm in this embodiment may include the following steps: first, a raw polyurethane rubber and various compounding auxiliaries (a vulcanization accelerator, a vulcanizing agent, a filler, a plasticizer, an antioxidant and other auxiliaries) are kneaded and discharged in an open mill or an internal mixer to obtain a rubber compound. Then, taking the rubber compound with proper size, placing the rubber compound in a tool, and carrying out compression molding. Wherein the compression molding condition is that the compression molding temperature is 100-200 ℃, preferably 150-180 ℃; the molding time is 50s to 500s, preferably 50s to 200 s; the pressure is 1MPa to 20 MPa.

Therefore, in the embodiment, the polyester plasticizer is used, and the dosage of the plasticizer is strictly controlled, so that the diaphragm has excellent swelling resistance to oleic acid, sun cream, grease and the like, the acoustic performance of the product is improved, and the service life of the product is prolonged.

According to one embodiment of the application, the mass change rate of the mixed polyurethane rubber film layer after being soaked in oleic acid at 65 ℃ for 96 hours is-5%. That is to say, the oil absorption rate of the mixing type polyurethane rubber film layer is-5%, when the oil absorption rate is less than-5%, low molecular substances in the MPU vibrating diaphragm can be separated out, the hardness is increased, and the F0 is increased greatly. When the oil absorption is more than 5%, the absorption amount of oleic acid is too large, the hardness is lowered, F0 is reduced too much, and the deformation probability of the diaphragm is increased due to the too large absorption amount.

According to one embodiment of the present application, the hardness of the compounded urethane rubber film layer is 30 to 95A. Preferably 40A to 60A. If the hardness of the compounded polyurethane rubber film layer is too small, the MPU has poor anti-swelling ability and is easy to generate polarization, resulting in poor THD (Total Harmonic Distortion). If the hardness of the mixing type polyurethane rubber film layer is too large, the elongation at break of rubber is reduced, the film is easy to break in low-temperature reliability verification to cause product failure, and the resonant frequency F0 of the vibrating diaphragm is too high to obtain perfect sound effect.

In some embodiments of the present application, the plasticizer has a number average molecular weight of 1000 to 5000. The plasticizer is a polyester plasticizer with the molecular weight of 1000-5000. Optionally, the plasticizer is selected from one or more of sebacic acid polyester plasticizer, adipic acid polyester plasticizer, and phthalic acid polyester plasticizer.

In this example, sebacic acid polyester plasticizer, adipic acid polyester plasticizer, phthalic acid polyester plasticizer and other plasticizers with large molecular weight and difficult precipitation were selected, and the amount of the selected plasticizers was strictly controlled, so that after the experiments with oleic acid, grease and sunscreen cream, the grease resistance and other chemical components of the compounded polyurethane rubber film layer were good, and F0 did not rise significantly, and still maintained good acoustic properties.

Preferably, the plasticizer is added in an amount of 0.5 to 5 parts by weight. When the addition amount of the plasticizer is less than 5 parts, the mixed polyurethane rubber film layer can completely resist the influence brought by oleic acid and sun cream.

According to one embodiment of the present application, a polyurethane green rubber includes hard segments and soft segments.

Wherein the hard segment is aromatic isocyanate. Optionally, the hard segment is selected from one or more of toluene diisocyanate, diphenylmethane diisocyanate (MDI), 1, 5-naphthalene diisocyanate, p-phenylene diisocyanate, and dimethylbiphenyl diisocyanate.

When aromatic isocyanate such as toluene diisocyanate, diphenylmethane diisocyanate, naphthalene 1.5-diisocyanate, p-phenylene diisocyanate, and dimethylbiphenyl diisocyanate is used in the hard segment, the polarity inside the material is relatively large, the bonding capability between molecules of the hard segment is strong, the intermolecular force is strong, the intermolecular gap is small, and the capability of entering oleic oil is weakened. The aliphatic hard segment, such as isophorone diisocyanate, m-dimethylene diisocyanate, 4' -dicyclohexylmethane diisocyanate, hydrogenated toluene diisocyanate and trimethylhexamethylene diisocyanate, has small intermolecular force, weak bonding capacity among hard segment molecules, large intermolecular gap, strong absorption capacity for oleic acid grease, and is easy to cause swelling, the vibrating diaphragm F0 is reduced, and the bottoming phenomenon is easy to occur.

The soft segment is at least one of polyester polyol, polycarbonate polyol and polycaprolactone polyol. It should be noted that when polyester polyol, polycarbonate polyol and polycaprolactone polyol are used in the soft segment, the material has a large internal polarity, the bonding capability between soft segment molecules is strong, the intermolecular force is strong, the intermolecular gap is small, and the capability of entering oleic oil is weakened. And MPU prepared from polyether polyol soft segments has small intermolecular force, weak bonding capacity among soft segment molecules, large intermolecular gap, strong absorption capacity for oleic acid grease, easy swelling phenomenon, reduced diaphragm F0 and easy bottoming phenomenon.

According to one embodiment of the present application, the vulcanizing agent is selected from one or more of dicumyl peroxide (DCP), 1 di-tert-butylperoxy-3, 3, 5-trimethylcyclohexane (3M), di-tert-butyl and peroxide, 2, 5-dimethyl-2, 5 (di-tert-butylperoxy) hexane, di-tert-butylperoxyisopropyl benzene (BIBP), Benzoyl Peroxide (BP), 2, 4-dichlorobenzoyl peroxide (DCBP), tert-butyl perbenzoate, sulphur.

The nature of vulcanization is crosslinking, and radicals are generated after peroxide is decomposed and react with active hydrogen or unsaturated double bonds on molecules in the MPU. Under the action of a vulcanizing agent, the MPU is converted from a linear structure into a three-dimensional network structure, the hardness and the modulus are improved, the MPU becomes an insoluble material, and the swelling capacity of the oil oleate under the action is enhanced.

The amount of vulcanizing agent has a great influence on the crosslinking reaction and the performance of the crosslinked rubber compound. When the vulcanizing agent is too small, the crosslinking reaction speed is slow, the crosslinking degree is low, the number of chemical bonds is small, the tensile strength is low, and the swelling capacity to chemicals is poor. When the dosage of the vulcanizing agent is excessive, the blooming phenomenon is easy to occur, the crosslinking degree is too high, the hardness is increased, the tearing strength and the elongation at break are linearly reduced, and when the power and the amplitude are excessive during vibration, the membrane rupture is easy to occur, so that the failure is easy to occur. Therefore, it is necessary to control the amount of the vulcanizing agent to be added, and in the present example, the amount of the vulcanizing agent to be added is 0.1 to 10 parts by mass. Preferably 1 to 8 parts by mass.

In some embodiments of the present application, the vulcanization accelerator is one or more of thiazoles (accelerator M, accelerator DM), sulfenamides (accelerator CZ, accelerator NOBS, accelerator DZ), thiurams (accelerator TMTD, accelerator TMTM), thioureas (accelerator NA-22), dithiocarbamates (accelerators ZDMC, ZDC), aldamines (accelerator H), arcs (accelerator D), xanthates (accelerator ZIX), triallyl isocyanate (TAIC), triallyl cyanurate (TAC), N-M-methylene-bismaleimide (HVA-2).

Furthermore, the addition amount of the vulcanization accelerator is 0.1-5 parts by mass, so that the vulcanization time can be further shortened, and the amount of the vulcanizing agent can be reduced.

According to one embodiment of the present application, the filler is selected from one or more of carbon black, white carbon black, talc, calcium carbonate, magnesium carbonate, dolomite, barium sulfate, zinc sulfide, aluminum powder, graphite, titanium dioxide, lithopone, phenol resin, petroleum resin, and styrene resin.

The filler will be described below by taking carbon black as an example.

Carbon black is an amorphous structure, and particles form aggregates by physicochemical bonding to each other. The primary structure of the carbon black is composed of aggregates, and van der waals force or hydrogen bonds exist among the aggregates, so that the aggregates can be aggregated into a spatial network structure, namely the secondary structure of the carbon black. The surface of carbon black has a group such as hydrogen, carboxyl group, lactone group, radical, quinone group, etc., which can undergo substitution, reduction, oxidation reaction, etc. When carbon black is added into MPU, due to strong interaction between the surface of the carbon black and a rubber interface, molecular chains slide on the surface of the carbon black relatively easily but are not easy to be separated from the carbon black when the material is stressed, an elastomer and the carbon black form a strong slidable bond, and the mechanical strength is increased.

Furthermore, the addition amount of the filler is 1-80 parts by mass, and the filler with the addition amount in the range can ensure that the carbon black and the rubber interface have strong interaction.

According to one embodiment of the application, the antioxidant is selected from one or more of antioxidant 1010, antioxidant 2, antioxidant 6, antioxidant 4, antioxidant 1076, antioxidant 168, antioxidant RD, antioxidant AW, antioxidant DD, antioxidant BLE, antioxidant 4010, 4010NA, 4020, 4030, 4040, antioxidant DNP, antioxidant H, antioxidant A, antioxidant D, antioxidant SP, antioxidant 264, antioxidant 2246-S, antioxidant NBC, and antioxidant MB. By adding the antioxidant, the effect of prolonging the service life can be achieved.

Further, the addition amount of the antioxidant is 0.5-5 parts by mass. Too little addition amount can not achieve the effect of prolonging the service life, while too much addition amount can not be well dissolved with the elastomer and is difficult to be uniformly dispersed, so that the mechanical property of the material is reduced, and the material is easy to be separated out to the surface along with the time. Therefore, the antioxidant within the range can play a good role in prolonging the service life.

According to one embodiment of the present application, the other additives include at least one of an anti-hydrolysis additive, zinc oxide, stearic acid, an ultraviolet absorber, and a color paste. Wherein stearic acid is used as an activator. By adding different auxiliary agents, the film layer can have different functions. For example, the film layer can be made to have an anti-hydrolysis function by adding an anti-hydrolysis auxiliary agent; the film layer can be made to have an ultraviolet absorbing function by adding an ultraviolet absorber.

It should be noted that the polyurethane contains a large number of polar groups inside, and thus the hydrophobicity is reduced and the affinity with water molecules is increased. And the polar groups, particularly ester groups, are easily degraded under high temperature and high humidity, and the molecular chain is broken, so that the product fails. Therefore, a certain amount of hydrolysis-resistant auxiliary needs to be added. The hydrolysis-resistant auxiliary agent reacts with carboxylic acid or carboxylic acid generated by hydrolysis of ester group to generate ureide derivative, so that carboxyl in the polyester is neutralized, further aggravation of hydrolysis is prevented, and the effect of chain scission regeneration is achieved.

Optionally, the hydrolysis-resistant auxiliary agent is carbodiimide, and the amount of the carbodiimide is 0 to 5 parts by mass, preferably 2 to 3 parts by mass.

In some embodiments of the present application, the thickness of the millable polyurethane rubber film layer is from 25 μm to 300. mu.m. Preferably 30 to 200. mu.m. If the thickness of the mixing type polyurethane rubber film layer is too thin, the damping performance of the vibrating diaphragm is poor, and the listening performance is poor. If the thickness of the mixing type polyurethane rubber film layer is too thick, the quality is increased, the sensitivity is deteriorated, and the weight reduction requirement of a wearable product cannot be met.

It should be noted that the diaphragm provided in the present application may constitute any sound generating device, such as the following typical sound generating devices: the vibration system comprises a vibrating diaphragm and a voice coil combined on one side of the vibrating diaphragm. The diaphragm can be a corrugated diaphragm or a flat diaphragm. When the sound generating device works, the voice coil can vibrate up and down to drive the vibrating diaphragm to vibrate under the action of the magnetic field force of the magnetic circuit system after being electrified, and the vibrating diaphragm can generate sound during vibration.

According to the sound generating mechanism of this application second aspect embodiment, including vibration system and with vibration system matched with magnetic circuit, vibration system includes the vibrating diaphragm and combines the voice coil loudspeaker voice coil on one side of the vibrating diaphragm, and magnetic circuit drive voice coil loudspeaker voice coil vibration is in order to drive the vibrating diaphragm sound production, and the vibrating diaphragm is the vibrating diaphragm of above-mentioned embodiment. Particularly, when sound generating mechanism during operation, the voice coil loudspeaker voice coil can vibrate in order to drive the vibrating diaphragm vibration from top to bottom under magnetic field effect of magnetic circuit after the voice coil loudspeaker voice coil circular telegram, can carry out the sound production during the vibrating diaphragm vibration.

As shown in fig. 1 and fig. 2, the sound generating device includes a diaphragm 15 prepared according to the above embodiment of the present disclosure, the diaphragm 15 may include a corrugated portion 151 and a dome portion 152, and the modified acrylate rubber film layer may be applied to the corrugated portion 151 of the diaphragm. Those skilled in the art can make corresponding adjustments according to actual product requirements, for example, the folded ring portion 151 protrudes toward the voice coil 11, the spherical top portion 152 is located on the lower surface of the folded ring portion 151, and a centering support plate is added to the vibration system.

As shown in fig. 3 and 4, the sound generating apparatus 100 according to the embodiment of the third aspect of the present application includes a casing 10, and a magnetic circuit 14 and a vibration system that are disposed in the casing 10, where the vibration system includes a voice coil 11, a first diaphragm 12, and a second diaphragm 13, a top of the voice coil 11 is connected to the first diaphragm 12, the magnetic circuit 14 drives the voice coil 11 to vibrate to drive the first diaphragm 12 to generate sound, two ends of the second diaphragm 13 are respectively connected to the casing 10 and a bottom of the voice coil 11, and the second diaphragm 13 is the diaphragm of the above embodiment.

That is to say, the sound generating apparatus 100 according to the embodiment of the present application may further include two diaphragms prepared according to the above embodiments of the present application, that is, the first diaphragm 12 and the second diaphragm 13, where 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 works, after the voice coil 11 is powered on, under the action of the magnetic field force of the magnetic circuit system 14, the voice coil 11 can vibrate up and down to drive the first diaphragm 12 to vibrate, and the first diaphragm 12 can generate sound when vibrating. The second diaphragm 13 can also vibrate up and down along with the voice coil 11, because the two ends of the second diaphragm 13 are connected with the bottom of the casing 10 and the bottom of the voice coil 11 respectively, the second diaphragm 13 can balance the vibration of the voice coil 11, so that the phenomenon of polarization of the voice coil 11 can be prevented, and the sound production effect of the sound production device 100 can be improved.

It should be noted that, the first diaphragm 12 and the second diaphragm 13 may be both the diaphragms of the embodiments of the present application, or one of the first diaphragm 12 and the second diaphragm 13 may be the diaphragm of the embodiments of the present application, which is not limited in this application.

The diaphragm of the sound generating apparatus of the present application is described in detail with reference to specific embodiments.

Comparative examples 1 to 3 and examples 1 to 4 were used in the present application. It should be noted that the comparative examples and examples were selected based on diaphragms having similar F0.

Wherein, a thermoplastic polyurethane elastomer (TPU) diaphragm is adopted in the comparative example 1, and the thickness of the diaphragm of the comparative example 1 is 53 μm.

In comparative example 2, a thermoplastic polyester elastomer (TPEE) composite diaphragm was used, and the diaphragm of comparative example 2 had a three-layer structure. The three-layer structure is divided into two surface layers and a middle layer. The middle layer is located between the two skin layers. Both of the skin layers were TPEE layers, each having a thickness of 18 μm. The middle layer is a polyacrylate pressure-sensitive adhesive film, and the thickness of the middle layer is 10 mu m.

The NBR rubber diaphragm was used in comparative example 3, and the diaphragm in comparative example 3 had a hardness of 55A and a thickness of 90 μm.

The MPU diaphragm of the present application was used in example 1, the hard segment used in example 1 was diphenylmethane diisocyanate (MDI), the plasticizer was a polyester type plasticizer, and the diaphragm in example 1 had a hardness of 50A and a thickness of 110 μm.

The MPU diaphragm of the present application was used in example 2, the hard segment used in example 2 was diphenylmethane diisocyanate (MDI), the plasticizer was a polyester type plasticizer, and the diaphragm in example 2 had a hardness of 45A and a thickness of 120 μm.

The MPU diaphragm of the present application was used in example 3, the hard segment used in example 3 was diphenylmethane diisocyanate (MDI), the plasticizer was a polyester type plasticizer, and the diaphragm in example 1 had a hardness of 42A and a thickness of 120 μm.

The MPU diaphragm of the present application was used in example 4, the hard segment used in example 4 was diphenylmethane diisocyanate (MDI), the plasticizer was a polyester type plasticizer, and the diaphragm in example 4 had a hardness of 65A and a thickness of 70 μm.

Specifically, the formulations of examples 1-4 are shown in Table 1 below.

TABLE 1 formulation

The following performance tests were conducted for examples and comparative examples, respectively.

(1) Mechanical Property test

Through elongation at break test, can verify the mechanical properties of the raw and other materials of the vibrating diaphragm of this application embodiment.

The specific operation is as follows:

the diaphragm raw materials in the embodiments 1 to 4 are taken, and the breaking elongation is tested according to the test standard of ASTM-D882, the gauge length is 30mm, and the tensile rate is 300 mm/min. The test results are shown in table 2 below.

TABLE 2 elongation at break test results

Vibrating diaphragm raw material	Elongation at break/%	Tear Strength/kgf/cm
			Example 1	500	45
Example 2	600	40
			Example 3	550	16
Example 4	180	12

With reference to table 1, in comparative examples 1 to 4, the addition amount of the vulcanizing agent in example 4 was the largest, and when the main rubber was 100 parts by mass, the vulcanizing agent was 8 parts by mass and the mass fraction was 8 wt%. Since the addition amount of the vulcanizing agent in example 4 is high, the crosslinking density is too high, and the binding force of the molecular chain is increased, so that the toughness of the material is reduced, as can be seen from table 2, the elongation at break of the raw material of the diaphragm in example 4 is 180%, the tear strength is 12kgf/cm, that is, the diaphragm is brittle, and the risk of breaking the diaphragm after reliability is high, it can be seen that the problem of breaking the diaphragm after reliability can be avoided by controlling the addition amount of the vulcanizing agent to be less than 8%.

(2) Resistance to chemicals

Through carrying out oil absorption rate and product defective rate test, can verify the resistance ability of the product of this application to chemicals.

During testing, the diaphragm raw materials corresponding to comparative examples 1 to 3 and examples 1 to 4 were cut into samples of 5cm × 5cm, and the mass of each sample was referred to as m. The sample was placed in a glass bottle containing oleic acid to ensure complete soaking, covered with a lid, and placed in an oven preheated to 65 ℃ for baking for 96 h. Then, the substrate was taken out, and after the greasy dirt on the surface was wiped with a dust-free cloth, the weight of the substrate was weighed to m 1. The oil absorption was calculated according to the formula (m1-m)/m × 100%. The detailed test data for oil absorption is shown in table 3.

Meanwhile, 100 sound generating devices are respectively made of the diaphragms of comparative examples 1 to 3 and examples 1 to 4. Oleic acid is dripped on each sounding device, and then the sounding devices are placed in an oven at 65 ℃ for baking for 96 h. Then, the proportion of the products deformed by the diaphragm is calculated after the products are disassembled, namely the reject ratio of the products is calculated, and the calculation result is recorded in table 3.

TABLE 3 oil absorption and product reject ratio test results of the diaphragms

As can be seen from the data in table 3, compared with the diaphragms of comparative example 1(TPU diaphragm), comparative example 2(TPEE composite diaphragm) and comparative example 3(HNBR diaphragm), the MPU diaphragm of the embodiment of the present application has a significantly lower oil absorption rate, has better oil resistance, and has better product stability and reliability. The oil absorption rates of the examples 1 and 4 are extremely low, and no adverse phenomenon occurs.

Further, as can be seen from table 1, the amount of the plasticizer added in example 2 is the largest relative to examples 1, 3 and 4. As can be seen from Table 2, in example 2, since the amount of the plasticizer added was large, precipitation occurred, the mass was reduced, and some defects occurred,

as can be seen from table 1, the vulcanizing agent added in example 3 was the smallest amount relative to examples 1, 2 and 4. As can be seen from Table 2, in example 3, since the amount of the vulcanizing agent used was small, the crosslinking point was small, the degree of crosslinking was low, the degree of densification of the crosslinked network was low, and a small portion of the grease molecules penetrated, the product portion corresponding to example 3 was poor.

(3) Product dimensional stability Performance test

Through testing the warpage degree of vibrating diaphragm, can verify the size stability performance of the product of this application.

First, 100 parallel products were produced for each of examples and comparative examples according to the production methods of examples 1 to 4 and comparative examples 1 to 3, respectively, and then the warpage of each parallel product was tested, respectively. The diaphragm corresponding to the comparative examples 1-2 is prepared in an air pressure forming mode. The diaphragms corresponding to the comparative example 3 and the examples 1 to 4 are prepared by adopting a mould pressing mode.

In the test, the following specific test method was employed.

The product was tested with a tester.

The tester comprises three parts: test probe, display and granite platform. Wherein, the test probe is a non-contact displacement sensor. During testing, the product is placed on three supporting points of a granite platform, the upper test probe and the lower test probe synchronously scan the product according to the same track, the distance from the test probes to the nearest surface of the product is recorded, and the difference value of the two test probes of each test point is solved, wherein half of the difference value is the test value of the warping degree of the test point. And taking the test value of the maximum warpage in each test point as the warpage of the product.

The warpage distribution of each parallel product is counted, and the test results are shown in the following table 4.

TABLE 4 test results of degree of warpage of diaphragm

From the test results in table 4, it can be seen that the degree of warpage of the diaphragm prepared by the mold pressing method is significantly better than that of the conventional thermoplastic elastomer diaphragm formed by air pressure. In addition, as can be seen from the test results of examples 1 to 4, the increase of the addition amount of the plasticizer and the reduction of the appropriate amount of the vulcanizing agent are both beneficial to the flatness of the diaphragm molding.

(4) Acoustic performance testing of products after chemical resistance

Through testing the F0 variable quantity after the experiments on the reliability of oleic acid, sunscreen cream and sebum, the acoustic performance of the product after resisting chemicals in the embodiment of the application can be verified.

When the oleic acid reliability test is performed, firstly, the corresponding diaphragm raw materials in comparative examples 1 to 3 and examples 1 to 4 are taken to be made into 100 sound generating devices respectively. F0(1) was tested for each sound emitting device. Then, after 1 μ l of oleic acid was dropped on the surface of the diaphragm, the diaphragm was baked in an oven at 65 ℃ for 96 hours, taken out and left to stand for 24 hours, and F0(2) after the experiment was tested, and the difference was calculated as F0(2) -F0 (1).

When the reliability test of the sunscreen cream resistance is carried out, 100 sound generating devices are manufactured by taking the corresponding diaphragm raw materials in comparative examples 1 to 3 and examples 1 to 4. F0(1) was tested for each sound emitting device. Then, uniformly coating sun cream on the surface of the diaphragm, and placing the diaphragm in an oven at 40 ℃ for 24 hours. After the sunscreen cream was wiped off with a dust-free cloth, it was left to stand for 24 hours, and F0(2) after the experiment was tested, and the difference was calculated as F0(2) -F0 (1).

When the sebum-resistant reliability test is carried out, 100 sound generating devices are respectively made of the corresponding diaphragm raw materials in comparative examples 1 to 3 and examples 1 to 4. F0(1) was tested for each sound emitting device. Then, uniformly coating sebum for preventing coating on the surface of the diaphragm, and then baking the diaphragm in an oven at 65 ℃ for 96 hours. After the sebum-repellent layer was wiped off with a dust-free cloth, F0(2) after the test was tested and the difference was calculated as F0(2) -F0 (1).

The results of each calculation are recorded in table 5.

TABLE 5 test results of F0 variation of diaphragm after reliability test of oleic acid, sunscreen cream and sebum

As can be seen from the data in table 5, compared to the thermoplastic elastomer type diaphragm raw materials in comparative example 1(TPU diaphragm), comparative example 2(TPEE composite diaphragm), and comparative example 3(HNBR diaphragm), the variation of F0 of the MPU diaphragm in the example of the present application is significantly better, and the decrease of F0 in the comparative example is larger, the displacement is increased in the product vibration, and the risk of bottoming is increased.

In an oleic acid reliability experiment and a sunscreen cream reliability experiment, the diaphragm of the TPEE composite film is seriously deformed, and F0 cannot be tested.

On the other hand, it can be seen from comparative examples 1, 3 and 4 that the lower the degree of crosslinking, the greater the sensitivity to various chemicals, and the greatest the change.

Comparing examples 1 and 2, it was found that in example 2 in which the amount of the plasticizer added was the largest, a remarkable increase in F0 occurred. This indicates that the plasticizer precipitates during the chemical reliability test, which results in an increase in hardness, thereby reducing the compliance of the diaphragm and increasing F0.

Combining the three chemical manifestations, it can be seen that oleic acid has the greatest impact on various materials, followed by sunscreen, which has less sebum impact.

In summary, in the embodiment of the application, the MPU prepared by using the polyester soft segment, the aromatic hard segment and the polyester plasticizer and increasing the amount of the vulcanizing agent has good acoustic performance and chemical resistance reliability, has good anti-swelling capability for common living chemicals such as oleic acid, grease and sunscreen cream, and the acoustic performance of the prepared diaphragm is not obviously changed after reliability experiments on oleic acid, grease and sunscreen cream. The sound generating mechanism of this application is after long-term the use, still can not influence the stability of product, gives user's splendid product experience.

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 for illustrative purposes only and are not intended to limit the scope of the present application. It will be appreciated by those skilled in the art that modifications may be made to the above embodiments without departing from the scope and spirit of the present application. The scope of the application is defined by the appended claims.

Claims

1. The utility model provides a sound generating mechanism's vibrating diaphragm, its characterized in that, the vibrating diaphragm contains mixed polyurethane rubber rete, mixed polyurethane rubber rete is formed by polyurethane crude rubber, vulcanizer, vulcanization accelerator, filler, plasticizer, antioxidant and other auxiliaries are mixed:

the addition amount of the polyurethane raw rubber is 100 parts by weight, the plasticizer is a polyester plasticizer, and the addition amount of the plasticizer is 0.5-10 parts by weight.

2. The diaphragm of the sounding device according to claim 1, wherein the mass change rate of the mixed polyurethane rubber film layer after being soaked in oleic acid at 65 ℃ for 96 hours is-5% to 5%.

3. The diaphragm of the sound generating apparatus as claimed in claim 1, wherein the plasticizer has a number average molecular weight of 1000 to 5000.

4. The diaphragm of claim 1, wherein the raw polyurethane rubber includes a hard segment and a soft segment, wherein the hard segment is selected from one or more of toluene diisocyanate, diphenylmethane diisocyanate, 1, 5-naphthalene diisocyanate, p-phenylene diisocyanate, and dimethylbiphenyl diisocyanate, and the soft segment is at least one of polyester polyol, polycarbonate polyol, and polycaprolactone polyol.

5. The diaphragm of the sound production device as claimed in claim 1, wherein the vulcanizing agent is added in an amount of 0.1 to 10 parts by mass, and the vulcanizing agent is one or more selected from dicumyl peroxide, 1 di-tert-butylperoxy-3, 3, 5-trimethylcyclohexane, di-tert-butyl peroxide, 2, 5-dimethyl-2, 5 (di-tert-butylperoxy) hexane, di-tert-butylperoxyisopropyl benzene, benzoyl peroxide, 2, 4-dichlorobenzoyl peroxide, tert-butyl perbenzoate, and sulfur.

6. The diaphragm of the sound production device according to claim 1, wherein the addition amount of the vulcanization accelerator is 0.1 to 5 parts by mass, and the vulcanization accelerator is one or more of thiazoles, sulfenamides, thiurams, thioureas, dithiocarbamates, aldamines, xanthates, triallyl isocyanate, triallyl cyanurate, and N, N-m-methylene-bismaleimide.

7. The diaphragm of the sound generating apparatus according to claim 1, wherein the filler is added in an amount of 1 to 80 parts by mass, and the filler is one or more selected from carbon black, white carbon black, talc, calcium carbonate, magnesium carbonate, dolomite, barium sulfate, zinc sulfide, aluminum powder, graphite, titanium dioxide, lithopone, phenol resin, petroleum resin, and styrene resin.

8. The diaphragm of the sound generating apparatus according to claim 1, wherein the antioxidant is added in an amount of 0.5 to 5 parts by mass, and is selected from one or more of antioxidant 1010, antioxidant 2, antioxidant 6, antioxidant 4, antioxidant 1076, antioxidant 168, antioxidant RD, antioxidant AW, antioxidant DD, antioxidant BLE, antioxidant 4010, 4010NA, 4020, 4030, 4040, antioxidant DNP, antioxidant H, antioxidant A, antioxidant D, antioxidant SP, antioxidant 264, antioxidant 2246-S, antioxidant NBC, and antioxidant MB.

9. The diaphragm of the sound-generating apparatus according to claim 1, wherein the other auxiliary agent includes at least one of an anti-hydrolysis auxiliary agent, zinc oxide, stearic acid, an ultraviolet absorber, and a color paste.

10. The diaphragm of the sound generating apparatus as claimed in claim 1, wherein the thickness of the mixed polyurethane rubber film layer is 25 μm to 300 μm.

11. A sound producing device, comprising a vibration system and a magnetic circuit system matched with the vibration system, wherein the vibration system comprises a diaphragm and a voice coil combined on 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 any one of claims 1 to 10.

12. A sound production device is characterized by comprising a shell, and a magnetic circuit system and a vibration system which are arranged in the shell, wherein the vibration system comprises a voice coil, a first vibrating diaphragm and a second vibrating diaphragm, the top of the voice coil is connected with the first vibrating diaphragm, the magnetic circuit system drives the voice coil to vibrate so as to drive the first vibrating diaphragm to produce sound, two ends of the second vibrating diaphragm are respectively connected with the shell and the bottom of the voice coil, and the second vibrating diaphragm is the vibrating diaphragm of any one of claims 1-10.