WO2022160683A1

WO2022160683A1 - Diaphragm and sound generating device

Info

Publication number: WO2022160683A1
Application number: PCT/CN2021/114294
Authority: WO
Inventors: 闫付臻; 王伟超; 李春
Original assignee: 歌尔股份有限公司
Priority date: 2021-01-29
Filing date: 2021-08-24
Publication date: 2022-08-04
Also published as: CN114827877A; CN114827877B

Abstract

A diaphragm and a sound generating device. The diaphragm (20) is prepared by using a casting polyurethane, which is prepared from a polyurethane prepolymer and a compounding agent by means of vulcanization. The polyurethane prepolymer is a block polymer formed by the alternate arrangement of hard and soft segments, wherein the hard segments are isocyanates, and the soft segments are polyol flexible long chains, and each end group of the block polymer is an isocyanate hard segment. The elastic recovery rate of the diaphragm (20) at 20% strain is greater than 70%, which can allow the diaphragm (20) to have a uniform thickness and the diaphragm is formed to be flat during the process of gas pressure forming, so as to ensure that same has good acoustic performance.

Description

Diaphragm and sound-generating device

technical field

The invention relates to the technical field of electro-acoustic conversion, in particular to a vibrating membrane and a sound-generating device.

Background technique

At present, the diaphragm in the sound generating device usually adopts a thermoplastic elastomer diaphragm, such as a thermoplastic polyurethane elastomer and a thermoplastic polyester elastomer diaphragm. Because thermoplastic polyurethane elastomer and thermoplastic polyester elastomer diaphragm have good plasticity, damping and temperature resistance, with the high demand for high power and high sound quality of speakers, thermoplastic elastomer diaphragm has been widely used in the field of speakers. Promote the application. However, the thermoplastic elastomer diaphragm is often formed by air pressure, and the stretching is uneven during the molding process, resulting in uneven thickness of the diaphragm after molding and uneven molding, resulting in a decrease in the yield of the diaphragm and an impact on the acoustic performance; On the other hand, the thermoplastic elastomer diaphragm has a linear structure. On the one hand, under large strain, the intermolecular slip is easy to occur, the viscous part increases, and the loss increases. After the external force is removed, the irrecoverable part increases, and the resilience Poor, the acoustic performance of the loudspeaker using this diaphragm becomes poor after large displacement vibration and high-demand waterproof test; moreover, in the long-term high-temperature stress test, the molecular chain is stretched at high temperature for a long time, and the molecular chain moves at high temperature The ability is enhanced, and slippage is more likely to occur. After the external force is removed, the recovery rate becomes poor, which makes the diaphragm deformed after the reliability of the loudspeaker using the diaphragm, resulting in poor performance and even the risk of membrane rupture.

SUMMARY OF THE INVENTION

The main purpose of the present invention is to provide a vibrating membrane and a sounding device, which aims to overcome the deformation and membrane rupture of the thermoplastic elastomer vibrating membrane after large displacement vibration, high-demand waterproof test or long-term high-temperature reliability, and can overcome the The defects of the thermoplastic elastomer diaphragm during the air pressure forming process make the diaphragm thickness uniform and the forming flat, thereby ensuring its good acoustic performance.

In order to achieve the above purpose, the diaphragm proposed by the present invention is prepared by using cast-type polyurethane, and the cast-type polyurethane is prepared by vulcanization of a polyurethane prepolymer and a compounding agent, and the polyurethane prepolymer is a block polymer, so The block polymer is formed by alternately arranging hard segments and soft segments, the hard segments are isocyanates, the soft segments are polyol flexible long chains, the end groups of the block polymers are all isocyanate hard segments, and the The elastic recovery rate of the diaphragm after 20% strain is greater than 70%.

In an optional embodiment, the compression set ratio of the diaphragm is less than 50%.

In an optional embodiment, the compounding agent includes a chain extender and a catalyst, and the diaphragm is formed by reacting a polyol and a polyisocyanate to generate a polyurethane prepolymer, then adding a chain extender and a catalyst, and injecting it into the diaphragm after mixing. In the processing mold, it is formed by cross-linking reaction.

In an optional embodiment, in terms of mass percentage, the amount of the chain extender is 10%-30% of the polyurethane prepolymer.

In an optional embodiment, the chain extender is a multifunctional low molecular alcohol or amine compound that can react with isocyanate.

In an optional embodiment, the chain extender is 3,3'-dichloro-4,4'-diaminodiphenylmethane, 2,5-diethyltoluenediamine, 1,2-bis( 2-Aminophenylthio)ethane, propylene glycol-bis(p-aminobenzoate), 3,5-diamino-4-chloro-benzoic acid isobutyl ester, 4,4-methylene-bis- (3-chloro-2,6-diethylaniline), 3,5-dimethylthiotoluenediamine, 1,4-butanediol, trimethylolpropane, triisopropanolamine, hydroquinone At least one in bis-hydroxyethyl ether, resorcinol-bis(P-hydroxyethyl) ether, triethanolamine; and/or, described catalyst selects butyltin dilaurate, stannous octoate, phosphoric acid, oleic acid for use , at least one of adipic acid, azelaic acid, phenylmercuric acetate, phenylmercuric propionate, and iron acetylacetonate.

In an optional embodiment, in terms of mass percentage, the amount of isocyanate used ranges from 2% to 50%; and/or, the isocyanate is selected from toluene diisocyanate, diphenylmethane diisocyanate, and hexamethylene diisocyanate. , naphthalene 1.5-diisocyanate, isophorone diisocyanate, m-dimethylene diisocyanate, p-phenylene diisocyanate, 3,3.-dimethyl-4,4.-biphenyl diisocyanate, 4,4' -at least one of dicyclohexylmethane diisocyanate, hydrogenated toluene diisocyanate, trimethylhexamethylene diisocyanate; and/or, described polyol is selected from polyester polyol, polyether polyol, polybutadiene type polyol At least one of alcohol, castor oil polyol, tetrahydrofuran-propylene oxide copolymer polyol, and epoxy resin modified polyol.

In an optional embodiment, the compounding agent further includes a filler, and the filler is at least one of carbon black, silica, clay, calcium carbonate, kaolin, talc, and glass microbeads; and/or, The compounding agent also includes an auxiliary agent, which is at least one of an antioxidant, an ultraviolet absorber, an anti-hydrolysis stabilizer, a plasticizer, a colorant, and an anti-aging agent.

In an optional embodiment, the hardness range of the diaphragm is 10A-95A.

In an optional embodiment, the hardness range of the diaphragm is 30A-85A.

In an optional embodiment, the thickness of the diaphragm ranges from 10 μm to 300 μm;

In an optional embodiment, the thickness of the diaphragm ranges from 10 μm to 200 μm;

The present invention also provides a sound-generating device. The sound-generating device includes a diaphragm, and the diaphragm is made of cast-type polyurethane. The cast-type polyurethane is made of polyurethane prepolymer and compounding agent through vulcanization. The polyurethane prepolymer is a block polymer, the block polymer is formed by alternating hard segments and soft segments, the hard segment is isocyanate, the soft segment is a long flexible polyol chain, and the block polymer is The end groups are all isocyanate hard segments, and the elastic recovery rate of the diaphragm after 20% strain is greater than 70%.

In the technical scheme of the present invention, the vibrating membrane is prepared from cast-type polyurethane, and the cast-type polyurethane is prepared by vulcanizing a polyurethane prepolymer and a compounding agent to obtain a cast-type polyurethane with a cross-linked structure. Since the cast polyurethane has a cross-linked structure, the molecules are networked, and there are chemical bonds between the molecules, it still has a relatively high recovery rate after a certain strain. The recovery rate of the diaphragm after 20% strain is greater than 70%, and the loudspeaker using the diaphragm still maintains good acoustic performance after large-displacement vibration and high-demand waterproof tests. In addition, the diaphragm of the present invention adopts a casting molding process. Compared with the thermoplastic elastomer diaphragm formed by air pressure, the diaphragm of the present invention has a uniform thickness, small residual stress after molding, and a flat diaphragm, thereby obtaining better acoustic performance.

Description of drawings

In order to explain the embodiments of the present invention or the technical solutions in the prior art more clearly, the following briefly introduces the accompanying drawings that need to be used in the description of the embodiments or the prior art. Obviously, the accompanying drawings in the following description are only These are some embodiments of the present invention, and for those of ordinary skill in the art, other drawings can also be obtained according to the structures shown in these drawings without creative efforts.

FIG. 1 is a schematic cross-sectional structural diagram of a sound producing device-acoustic speaker of the present invention.

Description of reference numbers:

标号label	名称 name	标号label		名称name
100100	扬声器speaker	3030	音圈voice coil

1010	外壳 shell	4040	磁路系统 Magnetic circuit system
2020	振膜Diaphragm

The realization, functional characteristics and advantages of the present invention will be further described with reference to the accompanying drawings in conjunction with the embodiments.

Detailed ways

The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

In addition, the technical solutions between the various embodiments can be combined with each other, but must be based on the realization by those of ordinary skill in the art. When the combination of technical solutions is contradictory or cannot be realized, it should be considered that the combination of such technical solutions does not exist. , is not within the scope of protection required by the present invention.

The invention provides a vibrating membrane, which is applied to a sound generating device.

The vibrating film of the present invention is prepared by using cast polyurethane, the cast polyurethane is a polyurethane prepolymer and a compounding agent is added through vulcanization, and the polyurethane prepolymer is a block polymer, and the block polymer is composed of hard segments and The soft segments are alternately arranged, the hard segment is isocyanate, the soft segment is a flexible long chain of polyol, the end groups of the block polymer are all isocyanate hard segments, and the strain recovery rate of the diaphragm is >70% after 20% strain.

The molecular structure of the polyurethane prepolymer of the present invention is as follows, wherein n is a natural number:

It can be seen from the above molecular structure that the polyurethane prepolymer is a block polymer. Generally, the soft segment is composed of the flexible long chain of oligomer polyol, and the hard segment, the hard segment and the soft segment are composed of isocyanate. Alternately arranged to form repeating structural units, the isocyanate group (-NCO) is located at the end of the block polymer, that is, the isocyanate group (-NCO) is terminated. The structure of the hard segment composed of isocyanate is as follows:

The structure of the soft segment composed of polyols is as follows:

-OR ₁ -O-

The role of the hard segment here is to provide hardness and modulus, while the soft segment provides toughness. The hardness, modulus and resilience of the diaphragm can be adjusted by adjusting the type and proportion of the hard segment and the type of the soft segment. Therefore, when preparing the diaphragm, the type and proportion of the hard segment, the type of the soft segment, and the weight and dosage of the compounding agent in the cast polyurethane can be adjusted to ensure that the prepared diaphragm has a good elastic recovery rate, which can be Optionally, it is ensured that the elastic recovery rate of the prepared diaphragm after 20% strain is greater than 70%. In addition, a compounding agent is added during the preparation of the diaphragm, and the compounding agent and the main material polyurethane prepolymer can undergo a vulcanization reaction under certain conditions to obtain a cross-linked structure. Molecular parts are connected by chemical bonds, so they still have a relatively high recovery rate after a certain strain.

However, the current thermoplastic elastomer diaphragm has a linear structure. On the one hand, under large strain, intermolecular slip easily occurs, the viscous part increases, and the loss increases. After the external force is removed, the irrecoverable part increases, and the resilience is relatively high. Poor, the acoustic performance of the loudspeaker using this diaphragm deteriorates after large displacement vibration and high-demand waterproof test; The movement ability is enhanced, and slippage is more likely to occur. After the external force is removed, the recovery rate becomes poor, which makes the diaphragm deformed after the reliability of the loudspeaker using the diaphragm, resulting in poor performance and even the risk of membrane rupture.

It can be understood that in the technical solution of the present invention, the diaphragm is made of cast polyurethane, and the cast polyurethane is a polyurethane prepolymer and a compounding agent is vulcanized to obtain a cast polyurethane with a cross-linked structure. Since the cast polyurethane has a cross-linked structure, the molecules are networked, and there are chemical bonds between the molecules, it still has a relatively high recovery rate after a certain strain. The recovery rate of the diaphragm after 20% strain is greater than 70%, and the loudspeaker using the diaphragm still maintains good acoustic performance after large-displacement vibration and high-demand waterproof tests. In addition, the diaphragm of the present invention adopts a casting molding process. Compared with the thermoplastic elastomer diaphragm formed by air pressure, the diaphragm of the present invention has a uniform thickness, small residual stress after molding, and a flat diaphragm, thereby obtaining better acoustic performance.

In the embodiment of the present invention, since the cast polyurethane is a cross-linked structure, the temperature resistance of the diaphragm will be improved, and permanent deformation will not easily occur during long-term high-temperature stretching at high temperature. Therefore, the preparation process of the diaphragm is adjusted reasonably. The types of raw materials and their added amounts can ensure that the compression permanent deformation rate of the diaphragm is less than 50%. The loudspeaker using this diaphragm can still maintain the original shape and performance after long-term high temperature reliability, and will not be deformed or broken. Membrane and other risks.

In the embodiment of the present invention, the compounding agent includes a chain extender and a catalyst. The diaphragm is formed by reacting polyol and polyisocyanate to form a polyurethane prepolymer, and then adding a chain extender and a catalyst. After mixing, it is injected into the diaphragm processing mold. Cross-linking reaction molding is obtained.

In the specific operation, the polyol and polyisocyanate are first reacted to form a liquid polyurethane prepolymer, and then a chain extender and a catalyst are added to mix evenly, and then injected into the diaphragm processing mold, and formed through a cross-linking reaction. Wherein, the reaction temperature of the cross-linking reaction is 20°C-230°C, and the reaction time is 3s-120min.

When adding a chain extender, the amount of the chain extender should be reasonably controlled to ensure that the prepared diaphragm has suitable hardness and resilience, so that it has suitable acoustic performance and reliability after being applied to a sound-emitting device. Optionally, in terms of mass percentage, the amount of chain extender is 10%-30% of the polyurethane prepolymer. If the dosage is less than 10%, the cross-linking is too low, the hardness of the diaphragm is small, and a thicker thickness is required to achieve the appropriate F0 (resonant frequency). After large strain or long-term high temperature stress, the molecular chain is prone to slip, resulting in the deformation of the diaphragm, which in turn affects the acoustic performance and reliability; if the dosage is more than 30%, the hardness of the diaphragm is too large and the elongation at break decreases. , the diaphragm becomes brittle, and the speaker using this diaphragm is prone to membrane cracking or even rupture after reliability. Therefore, the amount of the chain extender is controlled to be 10% to 30% of the prepolymer, and the diaphragm has a relatively suitable hardness, elongation at break and resilience to ensure that the sound device still maintains excellent performance before and after large strain or long-term stress. acoustic performance. For example, if the casting polyurethane is 100 parts by mass, the chain extender is 10 parts, 15 parts, 20 parts, 25 parts or 30 parts. It is not easy to produce film rupture and deformation when vibrating at high temperature for a long time.

It can be understood that in this example, the rebound performance of the diaphragm is optimized by adjusting the amount of the chain extender, so that it has a higher rebound elasticity, that is, when preparing the diaphragm, the amount of the chain extender is 10wt%. -30wt%, it can be ensured that the elastic recovery rate of the vibrating membrane prepared in this way is greater than 70% after 20% strain.

In the embodiment of the present invention, the chain extender is a multifunctional low molecular alcohol, amine or alcoholamine compound that can react with isocyanate.

Here the chain extender acts to cross-link with the isocyanate to adjust the hardness and resilience of the final diaphragm. The chain extender is usually 3,3'-dichloro-4,4'-diaminodiphenylmethane (MOCA), 2,5-diethyltoluenediamine, 1,2-bis(2-amino) Phenylthio)ethane, Propylene glycol-bis(p-aminobenzoate), 3,5-diamino-4-chloro-benzoic acid isobutyl ester, 4,4-methylene-bis-(3- chloro-2,6-diethylaniline), 3,5-dimethylthiotoluenediamine, 1,4-butanediol, trimethylolpropane, triisopropanolamine, hydroquinone bishydroxyethyl At least one of base ether, resorcinol-bis(P-hydroxyethyl) ether (HER), and triethanolamine. It can be understood that in this embodiment, the type of the chain extender is adjusted to ensure that the prepared diaphragm has high resilience, that is, when the diaphragm is prepared, the chain extender is selected and mixed with one or more of the above. , then it can be guaranteed that the elastic recovery rate of the vibrating membrane thus prepared is greater than 70% after 20% strain.

In the embodiment of the present invention, the catalyst selects at least one of butyltin dilaurate, stannous octoate, phosphoric acid, oleic acid, adipic acid, azelaic acid, phenylmercuric acetate, phenylmercuric propionate, and iron acetylacetonate.

The role of the catalyst here is to speed up the cross-linking reaction, thereby speeding up the film-forming speed of the cast polyurethane and improving the preparation efficiency of the diaphragm. When preparing the diaphragm, the catalyst can be selected from one or more mixtures of the above substances.

In the embodiment of the present invention, in terms of mass percentage, the amount of isocyanate used ranges from 2% to 50%.

If the content of the hard segment is too low, the hardness and modulus of the rubber are too low, the resilience is too poor, and the F0 (resonant frequency) is too low; if the content is too high, the hardness and modulus are too high, the loudness becomes low, and the low-frequency performance is poor. Therefore, it is necessary to reasonably control the amount of hardness isocyanate. Optionally, the amount of isocyanate is 2%, 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45% or 50%, so that better resilience performance can be obtained , more suitable F0 and low frequency performance.

It can be understood that in this embodiment, the prepared diaphragm has high resilience by adjusting the amount of hard-segment isocyanate, that is, when preparing the diaphragm, the amount of isocyanate in the range of 2% to 50% can be used. It is ensured that the elastic recovery rate of the vibrating membrane thus prepared after 20% strain is greater than 70%.

Further, by adjusting the types of hard-segment isocyanate and soft-segment polyol, it is ensured that the prepared diaphragm has high resilience.

Optionally, isocyanate selects toluene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), hexamethylene diisocyanate (HDI), naphthalene 1.5-diisocyanate (NDI), isophorone diisocyanate (IPDI) for use. ), m-dimethylene diisocyanate (XDI), p-phenylene diisocyanate (PPDI), 3,3.-dimethyl-4,4.-biphenyl diisocyanate (TODI), 4,4'-bicyclo At least one of hexylmethane diisocyanate (HMDI), hydrogenated toluene diisocyanate (HTDI), and trimethyl hexamethylene diisocyanate (TMDI).

Optionally, the polyol is selected from at least one of polyester polyol, polyether polyol, polybutadiene polyol, castor oil polyol, tetrahydrofuran-propylene oxide copolymer polyol, and epoxy resin modified polyol. .

It can be understood that the technical scheme of the present invention can adjust the rebound performance of the diaphragm by reasonably adjusting the amount and type of chain extender, the type and amount of hard-segment isocyanate, and the type of soft-segment polyol at the same time, so that the preparation The elastic recovery rate of the diaphragm after 20% strain is >70%.

It should be noted that the diaphragm provided by the present invention is made of cast polyurethane (CPU), which is different from thermoplastic polyurethane (TPU), which has a linear or branched structure and can be processed twice. After extending or coating to make a film, it is then made into a diaphragm by air pressure or molding, while the cast polyurethane of the present invention is a cross-linked structure and cannot be processed twice. Conventional urethane rubber, conventional urethane rubber is solid rubber, generally after plasticizing and kneading with compounding agents, it is calendered into a sheet or coated to form a film, and then compressed into a diaphragm by air pressure or molding, vulcanizing agent Usually sulfur, peroxides and isocyanates, the resulting diaphragm hardness can be adjusted in a narrow range, and the need for subsequent bonding of components such as casings leads to poor air tightness of the sounding device. The casting type polyurethane described in the present invention is a liquid rubber, which is cast and formed, and a chain extender is added for chain extension and cross-linking. The chain extender is usually alcohols, amines or alcoholamines. The adjustable range is wide, and because it is integrally formed with the casing, the sound-emitting device using the diaphragm has better air tightness.

In the embodiment of the present invention, when the diaphragm is prepared, its hardness should be reasonably designed to ensure that the loudspeaker using the diaphragm has excellent acoustic performance. Optionally, the hardness of the diaphragm is 10A-95A. 85A, 90A or 95A. If the hardness of the diaphragm is lower than 10A, the rigidity of the diaphragm is poor, and it is easy to generate polarization, resulting in poor THD (Total Harmonic Distortion). It is easy to break the film and cause product failure, and too much filler in the formula leads to defects. Preferably, when the hardness of the diaphragm is in the range of 30A-85A, the loudspeaker using the diaphragm has more excellent acoustic performance.

In the embodiment of the present invention, the thickness of the diaphragm is in the range of 10 μm-300 μm. When using cast polyurethane to prepare the diaphragm, the thickness of the diaphragm should be reasonably controlled to ensure that the sound-generating device using the diaphragm has excellent acoustic performance. If the thickness of the diaphragm is less than 10μm. The damping of the diaphragm is small, and the listening performance is poor; if the thickness of the diaphragm is greater than 300 μm, the weight of the diaphragm is too large, and the sensitivity becomes poor. Optionally, the thickness of the diaphragm is 10 μm, 50 μm, 100 μm, 150 μm, 200 μm, 250 μm or 300 μm. More preferably, when the thickness of the diaphragm is 10-200 μm, the sound generating device using the diaphragm has more excellent acoustic performance.

It should be noted that when preparing the diaphragm, the rebound performance of the diaphragm is adjusted by reasonably adjusting the amount and type of chain extender, the type of catalyst, the type and amount of hard-segment isocyanate, and the type of soft-segment polyol. At the same time, the hardness and thickness of the diaphragm are adjusted to make the hardness and thickness design more reasonable, so as to ensure that the sound-emitting device using the diaphragm has better acoustic performance.

Further, in the embodiment of the present invention, the compounding agent also includes a filler, and the filler is selected from at least one of carbon black, silica, clay, calcium carbonate, kaolin, talc, unsaturated carboxylic acid metal salt, and glass microbeads . On the basis of ensuring that the diaphragm has good resilience, fillers are added to enhance the strength of the diaphragm and further ensure that the diaphragm is not prone to rupture in a high temperature environment.

Further, in the embodiment of the present invention, the compounding agent also includes an auxiliary agent, and the auxiliary agent is selected from at least one of an antioxidant, an ultraviolet absorber, an anti-hydrolysis stabilizer, a plasticizer, a color paste, and an anti-aging agent. Among them, the addition of antioxidants can improve its antioxidant performance. The antioxidants can be antioxidants 1010, antioxidants 2, antioxidants 6, antioxidants 4, antioxidants 1076, antioxidants 168, etc. At least one of them is used in an amount of 0.5 to 5 parts by mass. Anti-hydrolysis stabilizer can improve the anti-hydrolysis stability of cast polyurethane, plasticizer can increase the processing performance of cast polyurethane, color paste can give a certain color, and antioxidant can improve its anti-aging performance. On the basis of ensuring the better resilience of the diaphragm, the addition of the above additives can further improve the comprehensive performance of the cast polyurethane, thereby improving the comprehensive performance of the diaphragm. Users can choose the above additives according to operational requirements and product requirements. one or more of the agents.

It can be understood that the castable polyurethane of the present invention is obtained by mixing the liquid polyurethane with a chain extender, a catalyst, a filler and other auxiliaries uniformly, and then injecting it into a corresponding mold and then cross-linking.

It should be noted that the cast polyurethane diaphragm of the present invention does not contain a foaming agent, because the addition of the foaming agent will cause the temperature resistance of the diaphragm to deteriorate, and problems such as deformation and even film rupture are likely to occur after reliability testing. , resulting in poor performance and affecting user experience. The use of cast polyurethane in the present invention aims to improve the resilience performance of the diaphragm, and ensures that the loudspeaker using the diaphragm can still maintain the original shape and performance after long-term high temperature reliability, and there will be no risks such as deformation and rupture of the diaphragm. , if the foaming agent is added, it will go against the concept of the present invention. At the same time, the preparation materials of the vibrating film of the present invention are relatively simple, the preparation process is relatively simple, the operation is relatively simple, and the preparation cost is relatively low.

The present invention also proposes a sound-generating device, including a sound-generating device main body and a vibrating membrane. The specific structure of the vibrating membrane can refer to the above-mentioned embodiments. All the beneficial effects brought by the technical solution will not be repeated here.

1 is an example sectional view of an acoustic speaker, wherein 10 is a speaker casing; 20 is the diaphragm according to the present invention; 30 is a voice coil; and 40 is a magnet. When the speaker is working, the electrical signal is input to the voice coil 30 of the product, and the voice coil 30 is subjected to the force of the magnetic field, and moves in different amplitudes and directions with the alternating change of the signal size and the positive and negative directions, thereby driving the diaphragm 20 to vibrate and emit sound , complete the electricity-electricity-sound energy conversion process.

The vibrating membrane of the present invention can be a ring-shaped vibrating membrane or a flat vibrating membrane, the vibrating membrane is arranged on the main body of the sound generating device, and the vibrating membrane is configured to be able to be driven to vibrate, thereby generating sound through vibration. A coil, a magnetic circuit system and other components may be arranged in the main body of the sounding device to drive the diaphragm to vibrate through electromagnetic induction. The sound producing device provided by the present invention has better sound producing effect and good durability.

In a specific embodiment, the Shore hardness of the diaphragm is 10-95A, and the thickness is in the range of 10-300 μm. At this time, the resonant frequency F0 of the micro-sounding device reaches 100-1500 Hz, and the low-frequency performance of the micro-sounding device is excellent. .

Since the diaphragm of the speaker needs to vibrate back and forth, it needs to have high resilience. In the embodiment of the present application, compared with the common thermoplastic elastomer diaphragm material, the CPU has a cross-linked structure, the molecules are networked, and there are chemical bonds between the molecules, so the resilience is better. The inventor further adjusted the ratio of the chain extender. When the mass of the chain extender was in the range of 10%-30%, the recovery rate of the CPU was >70% after a certain strain. It is required to maintain good acoustic performance after the waterproof test; in addition, the cross-linked structure itself improves the temperature resistance, and it is not easy to produce permanent deformation when stretched at high temperature for a long time, and the compression set rate is less than 50%. The speaker of the diaphragm can maintain the original shape and performance after long-term high-temperature reliability, and there will be no risks such as deformation and film rupture; on the other hand, conventional thermoplastic elastomer diaphragms are often formed by air pressure, and the molding process The uneven stretching in the middle leads to the uneven thickness of the diaphragm after molding and the defects such as uneven molding, which leads to a decrease in the yield of the diaphragm and affects the acoustic performance. The cast polyurethane diaphragm of the present invention adopts injection molding, The thickness of the diaphragm is uniform, the residual stress after molding is small, the diaphragm is flat, and better acoustic performance is obtained.

The diaphragm of the present invention will be described in detail below through specific examples, wherein the diaphragms shown in the embodiment and the comparative example have basically the same F0 at room temperature, and the difference of F0 is within 20 Hz. It is to be understood that the following description is exemplary only, rather than a specific limitation of the present invention.

Example 1: This example is a diaphragm prepared by using cast-type polyurethane. In parts by weight, the main raw materials of the diaphragm and its dosage are as follows: 100 parts of polyurethane prepolymer, 5 parts of white carbon black, trimethylolpropane 2 parts, 8 parts of 1,4-butanediol, wherein, trimethylolpropane and 1,4-butanediol are chain extenders, and the proportion of chain extenders is 10% of the polyurethane prepolymer. After mixing the above-mentioned raw materials evenly, injecting into the diaphragm mold, and vulcanizing at 100°C, the diaphragm can be prepared. The thickness of the prepared diaphragm is 110 μm and the hardness is 40A.

Example 2: This example is a diaphragm prepared by using cast polyurethane. In parts by weight, the main raw materials of the diaphragm and its dosage are as follows: 100 parts of polyurethane prepolymer, 10 parts of white carbon black, trimethylolpropane 5 parts, 25 parts of 1,4-butanediol, wherein, trimethylolpropane and 1,4-butanediol are chain extenders, and the amount of chain extenders is 30% of the polyurethane prepolymer. After the above-mentioned raw materials are mixed uniformly, they are injected into the diaphragm mold, and the diaphragm is formed after vulcanization at 100° C. The prepared diaphragm has a thickness of 70 μm and a hardness of 75A.

Comparative Example 1 is a thermoplastic polyurethane elastomer (TPU) diaphragm with a thickness of 80 μm and a hardness of 60A.

Comparative Example 2 is a thermoplastic polyester elastomer (TPEE) composite diaphragm, the diaphragm is a 3-layer structure, two of which are TPEE layers with a thickness of 15 μm, and the middle layer is a polyacrylate pressure-sensitive adhesive film with a thickness of 15 μm. 20μm.

The vibrating membranes in Example 1, Example 2, Comparative Example 1 and Comparative Example 2 were tested as follows:

(1) Warpage degree test after the diaphragm is formed:

In order to verify the performance of the product of the present invention, the warpage degree of the diaphragm in Example 1-2 and Comparative Example 1-2 was tested, and the specific test method was: test the product with a tester at room temperature, and the tester includes three parts: Test probes, monitors, and granite platforms, where the test probes are non-contact displacement sensors; during testing, place the product on the three fulcrums of the granite platform, and the upper and lower test probes scan the product synchronously according to the same trajectory, and record the test probe to The distance between the nearest surface of the product, and the difference between the two test probes at each test point is calculated, and half of the difference is the test value of the warpage of the test point, and the test with the largest warpage in each test point is taken The value is defined as the warpage of the product. According to the preparation methods of Example 1-2 and Comparative Example 1-2, 100 parallel products were made in each example, the warpage of each parallel product was tested respectively, and the distribution of warpage of each parallel product was counted. For the test results, see table 3.

Table 1 The test results of the warpage degree of the diaphragm in Example 1-2 and Comparative Example 1-2

It can be seen from the test results in Table 3 that the diaphragms of Comparative Examples 1-2 are prepared by air pressure molding, and Examples 1-2 are the cast polyurethane diaphragms of the present invention, which are prepared by injection molding. It can be clearly seen that, The warpage degree of the cast polyurethane vibrating film of the present invention is obviously better than that of the traditional air pressure forming thermoplastic elastomer vibrating film, and the flatness is better.

(2) Strain recovery rate and waterproof test

In order to verify the performance of the product of the present invention, the strain recovery of the raw materials of the diaphragm in Example 1-2 and Comparative Example 1-2 and the membrane refracting rate of the diaphragm after the 60m waterproof test of the sound-emitting device corresponding to the diaphragm were tested. The data are shown in Table 2.

The strain recovery test method is as follows: the stress relaxation is tested in the dynamic thermodynamic analyzer (DMA) tensile mode, the strain is set to 20%, the relaxation is 10 min, the recovery is 10 min, and the final recovery rate is recorded.

Table 2 Strain recovery rate and waterproof test data of the diaphragm in Example 1-2 and Comparative Example 1-2

振膜原材料Diaphragm raw material	应变恢复率Strain recovery rate	60m防水试验后膜折率Refractive index of membrane after 60m waterproof test
对比例1(TPU振膜)Comparative example 1 (TPU diaphragm)	70％70%	90％90%
对比例2(TPEE复合振膜)Comparative example 2 (TPEE composite diaphragm)	60％60%	100％100%
实施例1Example 1	85％85%	00
实施例2Example 2	90％90%	00

It can be seen from the test data in Table 2 that, compared with the diaphragms of Comparative Examples 1-2, the large-strain (20%) recovery rate of the cast polyurethane diaphragm of the present invention is higher, and it can still be used after the 60m waterproof test. return to its original shape, thus maintaining the same acoustic performance. Therefore, the cast polyurethane diaphragm of the present invention has higher resilience and better waterproof performance.

(3) Test of compression permanent change rate K:

In order to verify the performance of the product of the present invention, the compression set of the diaphragm raw materials in Example 1 and Comparative Example 1 was tested. The test standard refers to GB1683-81. Table 3.

Table 3 Compression set rate and high temperature long-term stress reliability test data of diaphragm deformation rate

It can be seen from the test data in Table 3 that compared with Comparative Example 1, the compression set of the cast polyurethane diaphragm of the present invention is smaller, indicating better resilience. The sound-generating device using the diaphragm can still return to its original shape after a high-temperature and long-term stress-type reliability test, and maintains good acoustic performance.

The above descriptions are only preferred embodiments of the present invention, and are not intended to limit the scope of the present invention. Under the inventive concept of the present invention, any equivalent structural transformations made by the contents of the present invention, or directly/indirectly applied to other related All technical fields are included in the scope of patent protection of the present invention.

Claims

A vibrating membrane is characterized in that, the vibrating membrane is made of cast polyurethane, the cast polyurethane is a polyurethane prepolymer and a compounding agent is added through vulcanization, and the polyurethane prepolymer is a block polymer , the block polymer is formed by alternating hard segments and soft segments, the hard segment is isocyanate, the soft segment is a polyol flexible long chain, and the end groups of the block polymer are all isocyanate hard segments, The elastic recovery rate of the diaphragm after 20% strain is greater than 70%.
The diaphragm of claim 1, wherein the compression set ratio of the diaphragm is less than 50%.
The diaphragm of claim 1, wherein the complexing agent comprises a chain extender and a catalyst, and the diaphragm is formed by reacting polyol and polyisocyanate to form a polyurethane prepolymer, and then adding the chain extender and the catalyst , mixed and injected into the diaphragm processing mold, and obtained by cross-linking reaction molding.
The diaphragm according to claim 3, wherein the amount of the chain extender is 10%-30% of the polyurethane prepolymer in terms of mass percentage.
The diaphragm of claim 3, wherein the chain extender is a multifunctional low-molecular alcohol or amine compound that can react with isocyanate.
The diaphragm according to claim 3, wherein the chain extender is 3,3'-dichloro-4,4'-diaminodiphenylmethane, 2,5-diethyltoluenediamine , 1,2-bis(2-aminophenylthio)ethane, propylene glycol-bis(p-aminobenzoate), 3,5-diamino-4-chloro-benzoic acid isobutyl ester, 4,4 -Methylene-bis-(3-chloro-2,6-diethylaniline), 3,5-dimethylthiotoluenediamine, 1,4-butanediol, trimethylolpropane, trimethylolpropane At least one of isopropanolamine, hydroquinone bis-hydroxyethyl ether, resorcinol-bis(P-hydroxyethyl) ether, and triethanolamine;

And/or, the catalyst is selected from at least one of butyltin dilaurate, stannous octoate, phosphoric acid, oleic acid, adipic acid, azelaic acid, phenylmercuric acetate, phenylmercuric propionate, and iron acetylacetonate.
The diaphragm according to claim 3, characterized in that, in terms of mass percentage, the amount of the isocyanate used ranges from 2% to 50%;

And/or, described isocyanate selects toluene diisocyanate, diphenylmethane diisocyanate, hexamethylene diisocyanate, naphthalene 1.5-diisocyanate, isophorone diisocyanate, m-dimethylene diisocyanate, terephthalic diisocyanate for use At least one of isocyanate, 3,3.-dimethyl-4,4.-biphenyl diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, hydrogenated toluene diisocyanate, and trimethylhexamethylene diisocyanate;

And/or, the polyol is selected from at least one of polyester polyol, polyether polyol, polybutadiene polyol, castor oil polyol, tetrahydrofuran-propylene oxide copolymer polyol, and epoxy resin modified polyol. A sort of.
The diaphragm according to claim 3, wherein the compounding agent further comprises a filler, and the filler is at least one of carbon black, silica, clay, calcium carbonate, kaolin, talc, and glass beads kind;

And/or, the compounding agent further includes an adjuvant, and the adjuvant is at least one of an antioxidant, an ultraviolet absorber, an anti-hydrolysis stabilizer, a plasticizer, a colorant, and an anti-aging agent.
The diaphragm according to any one of claims 1 to 8, wherein the hardness of the diaphragm is in the range of 10A-95A.
The diaphragm according to claim 9, wherein the hardness of the diaphragm is in the range of 30A-85A.
The diaphragm according to any one of claims 1 to 8, wherein the thickness of the diaphragm is in the range of 10 μm-300 μm.
The diaphragm according to any one of claims 11, wherein the thickness of the diaphragm is in the range of 10 μm-200 μm.
A sound producing device, characterized in that it comprises the diaphragm according to any one of claims 1 to 12.