CN113490125B

CN113490125B - Vibrating diaphragm capable of being used for sound production device and sound production device

Info

Publication number: CN113490125B
Application number: CN202110603404.XA
Authority: CN
Inventors: 王婷; 李春
Original assignee: Goertek Inc
Current assignee: Goertek Inc
Priority date: 2021-05-31
Filing date: 2021-05-31
Publication date: 2023-06-27
Anticipated expiration: 2041-05-31
Also published as: CN113490125A; WO2022253106A1

Abstract

The invention relates to a vibrating diaphragm which can be used for a sound generating device and the sound generating device. A diaphragm for use in a sound emitting device, comprising: thermoplastic polyester elastomer film layers formed by copolymerizing hard segments of polynaphthalene dicarboxylic acid ester and soft segments of polyether and/or aliphatic polyester; the thickness of the vibrating diaphragm is 10-200 mu m, and the loss factor of the thermoplastic polyester elastomer film layer at the temperature of 23 ℃ is 0.1-0.3. The sound generating device comprises a vibration system and a magnetic circuit system matched with the vibration system, wherein the vibration system comprises a vibrating diaphragm and a voice coil combined on one side of the vibrating diaphragm. The invention solves the problem of poor high and low temperature resistance of the existing elastomer, and can well consider the basic problems of rigidity, rebound resilience, damping and the like required by vibration of the vibrating diaphragm, so that the vibrating diaphragm has lower distortion, and the acoustic performance of the vibrating diaphragm is greatly improved.

Description

Vibrating diaphragm capable of being used for sound production device and sound production device

Technical Field

The invention relates to the technical field of electroacoustic, in particular to a vibrating diaphragm capable of being used for a sound generating device and the sound generating device.

Background

With the increasing demands in industry for speaker performance, more and more products are pursuing higher loudness, high quality sound quality, and high level of waterproofing. The existing loudspeaker diaphragm adopts composite structure material, it includes: engineering plastics (such as PEEK, PAR, PET, PI, PEI) are used as a base layer, acrylic rubber, silica gel layers and the like are used as damping layers, and thermoplastic elastic materials are used as rebound layers, wherein modulus and damping are both achieved. When the composite film is used as a loudspeaker diaphragm, the composite film cannot completely meet the requirements of higher loudness, high-quality tone quality, high-grade waterproof and the like. In recent years, as the thermoplastic polyester elastomer can effectively improve the rebound resilience of the diaphragm, reduce the folding of the diaphragm, reduce the distortion problem generated in the abrupt vibration process of the diaphragm, and the like, more and more products adopt the material to be used as the diaphragm of the loudspeaker, thereby meeting the requirements of the products on high quality such as tone quality, water resistance, and the like.

In the related art, a diaphragm for a speaker is proposed, in which a thermoplastic polyester elastomer film layer is used, which is made of a polyethylene terephthalate as a hard segment. However, the damping of the vibrating diaphragm is low, and the phenomenon of polarization and distortion is very easy to occur when the loudspeaker works; the diaphragm has a small use temperature range and poor high-temperature and low-temperature resistance, so that the normal use of the loudspeaker in an extreme temperature environment is influenced.

Disclosure of Invention

The invention mainly aims to provide a vibrating diaphragm for a sound production device, wherein a thermoplastic polyester elastomer consists of a hard segment of polynaphthalene dicarboxylic acid ester and a soft segment of polyether/aliphatic polyester, and the material not only solves the problem of poor high temperature resistance of the traditional elastomer, but also can well consider the rigidity and rebound resilience, higher damping and lower distortion required by vibration of the vibrating diaphragm.

Another object of the present invention is to provide a sound generating device, which is provided with the vibrating diaphragm of the present invention, and the vibrating diaphragm is used for vibration sound generation.

Still another object of the present invention is to provide a sound generating apparatus provided with the above-mentioned diaphragm for balancing the vibration of the voice coil.

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

A diaphragm for a sound generating device according to an embodiment of the first aspect of the present invention includes:

a thermoplastic polyester elastomer film layer formed by copolymerizing a hard segment containing polynaphthalene dicarboxylic acid ester and a soft segment containing polyether and/or aliphatic polyester;

wherein the thickness of the vibrating diaphragm is 10-200 mu m, and the loss factor of the thermoplastic polyester elastomer film layer at the temperature of 23 ℃ is 0.1-0.3.

According to some embodiments of the invention, the soft segments in the thermoplastic polyester elastomer film layer comprise at least one of polytetrahydrofuran ether, polycaprolactone, polybutylene adipate, polyethylene oxide, aliphatic polycarbonate.

According to some embodiments of the invention, the hard segments in the thermoplastic polyester elastomer film layer are present in an amount of 30% to 80% by weight.

According to some embodiments of the invention, the hard segments in the thermoplastic polyester elastomer film layer are present in an amount of 50% to 75% by weight.

According to some embodiments of the invention, the content of the hard segment of polynaphthalene dicarboxylic acid in the thermoplastic polyester elastomer film layer is 50 to 60%.

According to some embodiments of the invention, the thermoplastic polyester elastomer film layer has a storage modulus of 50MPa to 500MPa in an environment of 23 ℃.

According to some embodiments of the invention, the thermoplastic polyester elastomer film layer has a storage modulus of 50MPa to 350MPa in an environment of 23 ℃.

According to some embodiments of the invention, the ratio between the storage modulus in both the MD and TD directions of the thermoplastic polyester elastomer film layer is 80-120:100.

According to some embodiments of the invention, the diaphragm is of a single-layer structure, and the diaphragm comprises only one layer of the thermoplastic polyester elastomer film.

According to some embodiments of the invention, the diaphragm has a thickness of 20 μm to 150 μm.

According to some embodiments of the invention, the diaphragm is a composite film structure in which at least one surface layer is the thermoplastic polyester elastomer film layer.

According to some embodiments of the invention, the diaphragm is the composite film structure in which the thermoplastic polyester elastomer film layers and the adhesive layers are alternately stacked, and both surface layers of the composite film structure are the thermoplastic polyester elastomer film layers.

According to some embodiments of the invention, each of the thermoplastic polyester elastomer film layers has a thickness of 5 μm to 50 μm.

According to some embodiments of the invention, each layer of the glue layer comprises one or more of a silicone glue layer, an acrylic glue layer;

and/or the thickness of each layer of the adhesive layer is 2-50 mu m. .

According to some embodiments of the invention, the glass transition temperature of the glue layer is less than or equal to-10 ℃.

According to the preparation method of the diaphragm, the thermoplastic polyester elastomer film layer is prepared by the following steps:

carrying out copolymerization reaction on a polynaphthalene dicarboxylic acid ester prepolymer with molecular weight of 10000-50000 and a polyether prepolymer or aliphatic polyester prepolymer with molecular weight of 500-5000, wherein the temperature of the copolymerization reaction is preferably 230-265 ℃, and the reaction time is preferably 0.5-2 h; granulating and extruding the film;

wherein, catalyst and stabilizer are preferably added in the copolymerization reaction, and the stabilizer is preferably polycarbodiimide.

According to the third aspect of the invention, the sound generating device comprises a vibration system and a magnetic circuit system matched with the vibration system, the vibration system comprises a vibrating diaphragm and a voice coil combined on one side of the vibrating diaphragm, the magnetic circuit system drives the voice coil to vibrate so as to drive the vibrating diaphragm to generate sound, and the vibrating diaphragm adopts the vibrating diaphragm according to the first aspect of the invention.

According to the sound generating device, the sound generating device comprises 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 generate sound, two ends of the second vibrating diaphragm are respectively connected with the bottom of the shell and the bottom of the voice coil, and the second vibrating diaphragm is the vibrating diaphragm according to the embodiment of the first aspect of the invention.

Compared with the prior art, the invention at least achieves the following technical effects:

the diaphragm provided by the invention utilizes the advantages of the hard segment of the polynaphthalene dicarboxylic acid ester and the soft segment of the polyether and/or the aliphatic polyester, plays a synergistic effect, is long in use and short in service, can give consideration to rigidity, rebound resilience, high-temperature resistance and low-temperature resistance, and has higher damping property and lower distortion, so that the service temperature range of the diaphragm can be increased, and the sounding effect of the diaphragm is improved.

The naphthalene ring structure of the polynaphthalene dicarboxylic acid ester has higher rigidity, the steric hindrance of the molecular chain segment is larger than that of the benzene ring, and when the material is acted by external force, more external force can be consumed, so that the thermoplastic polyester elastomer has good damping property. Meanwhile, polyether and aliphatic polyester can form a better block structure with polynaphthalene dicarboxylic acid ester, and lower glass transition temperature can be realized, so that the low temperature resistance of the diaphragm can be improved. The thermoplastic polyester elastomer film layer formed by respectively crosslinking and copolymerizing the hard segment and the soft segment can be matched with the requirements of the diaphragm in the high-performance loudspeaker.

Drawings

Various other advantages and benefits will become apparent to those of ordinary skill in the art upon reading the following detailed description of the preferred embodiments. The drawings are only for purposes of illustrating the preferred embodiments and are not to be construed as limiting the invention.

FIG. 1 is a graph of loss modulus and storage modulus versus temperature for examples and comparative examples;

FIG. 2 is a graph showing the variation of the loss factor with temperature for the examples and comparative examples;

fig. 3 is a schematic structural diagram of a speaker according to the present invention;

FIG. 4 is a schematic diagram of the sound emitting vibration unit of FIG. 3;

FIG. 5 is a schematic cross-sectional view of a diaphragm;

FIG. 6 is a plot of the frequency response of the examples and comparative examples;

fig. 7 is a graph of the total harmonic distortion of the examples and comparative examples.

Detailed Description

Embodiments of the present invention will be described in detail below with reference to examples, but it will be understood by those skilled in the art that the following examples are only for illustrating the present invention and should not be construed as limiting the scope of the present invention. The specific conditions are not noted in the examples and are carried out according to conventional conditions or conditions recommended by the manufacturer. The raw materials, reagents or instruments used are not identified to the manufacturer and are conventional products commercially available or can be prepared according to the prior art.

The invention provides a vibrating diaphragm for a sound generating device, which comprises:

a thermoplastic polyester elastomer film layer formed by copolymerizing a hard segment containing polynaphthalene dicarboxylic acid ester and a soft segment containing polyether and/or aliphatic polyester; wherein the thickness of the vibrating diaphragm is 10-200 mu m, and the loss factor of the thermoplastic polyester elastomer film layer at the temperature of 23 ℃ is 0.1-0.3.

Through tests, the diaphragm prepared from the thermoplastic polyester elastomer film layer has remarkable advantages compared with the diaphragm prepared from the polybutylene terephthalate serving as a hard segment, and particularly shows the aspects of damping, high temperature resistance, distortion inhibition and the like.

The polynaphthalene dicarboxylic acid ester refers to a material formed by polymerizing naphthalene dicarboxylic acid and any alcohol, and can be monohydric alcohol or polyhydric alcohol, saturated alcohol or unsaturated alcohol, such as ethanol, ethylene glycol, propanol, butanol, butanediol, propylene glycol, glycerol, benzyl alcohol, vinyl alcohol and the like, and can be polymerized by optionally one or a plurality of alcohols and naphthalene dicarboxylic acid, preferably dihydric alcohol, especially lower dihydric alcohol (butanediol, ethylene glycol and the like) is adopted.

The polyether of the present invention may be any alcohol-to-alcohol polymer useful in elastomers, or alkylene oxide polymers, including but not limited to typical polyethylene glycol ethers, polytetrahydrofuran ethers, polyethylene oxides, polypropylene oxides, polybutylene oxides, and the like, preferably polytetrahydrofuran ethers, which more readily form a better block structure than polyester soft segments when copolymerized with polynaphthalene dicarboxylate, and can achieve lower glass transition temperatures and low temperature resistance.

The aliphatic polyesters of the present invention include, but are not limited to, polycaprolactone, polybutylene adipate, polybutylene succinate, aliphatic polycarbonates, polylactic acid, and the like.

As the soft segment of the thermoplastic polyester elastomer in the present invention, it may be either polyether or aliphatic polyester, or a mixture of both, preferably comprising at least one of polytetrahydrofuran ether, polycaprolactone, polybutylene adipate, polyethylene oxide, aliphatic polycarbonate, for example, any one of the above, or a combination of polytetrahydrofuran ether, polycaprolactone, or a combination of polycaprolactone, polybutylene adipate, or a combination of polytetrahydrofuran ether, polyethylene oxide, or a combination of tetrahydrofuran ether, aliphatic polycarbonate, or a combination of polytetrahydrofuran ether with any two other, etc.

Meanwhile, the proportion of the hard segment and the soft segment in the thermoplastic polyester elastomer has a significant effect on the performances such as temperature resistance and damping property, and the weight percentage of the hard segment is preferably 30% -80%, such as 30%, 40%, 50%, 60%, 70%, 80% and the like. When the content exceeds 80%, the hardness and modulus of the thermoplastic polyester elastomer material are obviously improved, and meanwhile, the elastic region is reduced, so that the toughness and rebound resilience of the material are insufficient, and the material has no obvious advantages compared with the conventional engineering plastic vibrating diaphragm material. When the content is less than 30%, the rigidity, damping and strength of the whole material are not obviously improved by the hard polynaphthalate segment, and the thermoplastic polyester elastomer of the hard polynaphthalate segment has no obvious advantage compared with the thermoplastic polyester elastomer material of the hard polynaphthalate segment, and the cost is increased, so that the selection is not recommended. In addition, 50% to 75%, for example, 50%, 53%, 55%, 57%, 60%, 63%, 65%, 70%, 75% and the like are more preferable. Further, the weight percentage of hard segments in the thermoplastic polyester elastomer may be 50% to 60%.

Furthermore, due to the complexity of the chemical composition of the polymer, it is necessary to limit its performance for incorporation into practical applications.

For the diaphragm, the loss factor of the thermoplastic polyester elastomer film layer is 0.1-0.3 (data of DMA temperature scanning mode, 1Hz vibration frequency, 3 ℃/min heating rate and 23 ℃ loss factor) and has good damping property, and the requirements of products on high performance and low performance can be met. If the loss factor is less than 0.1, the polyester elastomer having a hard segment of a polyester is not excellent in terms of damping, and a thermoplastic polyester elastomer film having a hard segment of a polyester is preferable because of the difficulty in synthesis and the cost. If the loss factor of the diaphragm is higher than 0.2, the transient response of the material is lost due to the damping promotion of the material, the diaphragm cannot perfectly realize the feedback of the input signal, and the sound quality is sacrificed. In addition, 0.1 to 0.2, for example, 0.12, 0.14, 0.15, 0.16, 0.17, 0.18, 0.19, 0.2, and the like are more preferable.

In some embodiments, the thermoplastic polyester elastomer film layer has a storage modulus of 50 to 500Mpa (data for a DMA temperature sweep mode, a 1Hz vibration frequency, a 3 ℃/min ramp rate, and 23 ℃). It will be appreciated that when the modulus is too low, insufficient stiffness of the diaphragm, if the F0 (lowest resonance frequency) required for the product is reached, can only be achieved by increasing the thickness, but an increase in thickness will bring about an increase in the mass of the diaphragm, will lose its vibration space and will reduce the sensitivity of the mass control zone. When the modulus is high, the flexibility and rebound resilience of the material are poor, and in order to obtain high loudness, the product needs to have a large displacement of the diaphragm, and at this time, the increase of the modulus has an adverse effect. More preferably 50 to 350MPa, in some embodiments the thermoplastic polyester elastomer film may have a storage modulus of 50MPa, 150MPa, 200MPa, 250MPa, 300MPa, 350MPa, etc.

In some embodiments, in order to ensure the consistency of vibration of the loudspeaker diaphragm and reduce the polarization of products, the ratio of the storage modulus of the thermoplastic polyester elastomer film layer in the MD and the TD is 80-120:100. In other words, the difference in storage modulus in both the MD and TD directions of the thermoplastic polyester elastomer film layer is controlled within.+ -. 20%, preferably within.+ -. 10%, more preferably within.+ -. 5%.

The thermoplastic polyester elastomer film with the hard polynaphthalate section can well give consideration to the modulus and rebound resilience required by vibration of the diaphragm and has relatively high damping (more than 0.1), so that the film can be used for preparing a diaphragm with a single-layer film or a composite film with other layers (such as a glue layer, a plastic layer and the like) in a laminating way. When the composite film is used, at least one surface layer is a thermoplastic polyester elastomer film layer.

In a single-layer diaphragm comprising only a thermoplastic polyester elastomer film layer, the thickness is preferably 10 to 200 μm, more preferably 20 to 150 μm. It can be understood that when the thickness of the diaphragm is too low, the rigidity of the diaphragm is easy to be insufficient, the difficulty of film making is high, the mass of the diaphragm is increased, and the sensitivity is lost. Further, the thickness of the single-layer diaphragm including the thermoplastic polyester elastomer film layer may be 20 μm, 30 μm, 40 μm, 50 μm, 60 μm, 70 μm, 80 μm, 90 μm, 100 μm, 110 μm, 120 μm, 130 μm, 140 μm, 150 μm, and so on.

According to the requirements of products on loudness, tone quality and the like, the loudspeaker diaphragm can also be made of a composite material of a thermoplastic polyester elastomer film, wherein the composite material comprises a thermoplastic polyester elastomer film layer which is only one polynaphthalate hard segment, and preferably has a structure of alternately overlapping with a glue film layer, and the thermoplastic polyester elastomer film layer is a surface layer. If a composite structure is used, sensitivity and vibration space loss due to excessive material thickness are avoided, and the thickness of the thermoplastic polyester elastomer film layer is preferably 5-50 μm. For example, the thickness of the thermoplastic polyester elastomer film layer may be 5 μm, 10 μm, 15 μm, 20 μm, 25 μm, 30 μm, 35 μm, 40 μm, 45 μm, 50 μm.

For the adhesive layer in the composite film, it may be typical in the art, for example, each adhesive layer may include one or more of a silica adhesive layer and an acrylic adhesive layer, that is, each adhesive layer may further include a silica adhesive layer or an acrylic adhesive layer, and the adhesive layer may further include both a silica adhesive layer and an acrylic adhesive layer. Preferably, the adhesive layer may include a pressure sensitive adhesive film. The pressure-sensitive adhesive film is convenient to use, lamination among multiple layers can be realized through a simple composite process, and 180-degree stripping force after lamination needs to be satisfied: not less than 150g/25mm. In order to ensure that the loudspeaker diaphragm can still maintain good tone quality at low temperature, the glass transition temperature of the adhesive layer is not higher than-10 ℃. When the glass transition temperature of the adhesive layer is higher than-10 ℃, the modulus of the adhesive film layer can be rapidly increased, so that the rigidity of the material is overhigh, the F0 of the product is obviously increased, the toughness of the diaphragm is reduced, and the risk of film cracking is easily caused. Alternatively, the thickness of each glue layer may be 2 to 50 μm, for example, the thickness of each glue layer may be 2 μm, 10 μm, 15 μm, 20 μm, 25 μm, 30 μm, 35 μm, 40 μm, 45 μm, 50 μm, etc.

The preparation method of the thermoplastic polyester elastomer film layer only involves conventional procedures, including copolymerization reaction, preparation of granular resin, and finally forming of a film material by using extrusion equipment.

Wherein, the technological conditions of the copolymerization reaction have a certain influence on the performance of the elastomer, and the prepolymer is generally selected for the hard segment and the soft segment while the raw materials are ensured to be carried out in a molten state.

In some preferred embodiments, the polynaphthalene dicarboxylic acid ester prepolymer is selected from the group consisting of prepolymers having a molecular weight of 10000 to 50000, such as 10000, 20000, 30000, 40000, 50000, etc. The prepolymer of the soft segment preferably has a molecular weight of 500 to 5000, for example 500, 1000, 2000, 3000, 4000, 5000, etc. The temperature of the copolymerization reaction is preferably 230-265 ℃, and the reaction time is preferably 0.5-2 h.

In the copolymerization reaction, a catalyst and a stabilizer are usually added, the two types can be common typical auxiliary agents, for example, the stabilizer is preferably polycarbodiimide, the catalyst is preferably n-butyl titanate, and the dosage of the two can be adjusted according to practical conditions. The end point of the copolymerization reaction is generally based on the resin becoming uniformly transparent.

Granulation is usually carried out in a microtome or granulator.

In the extrusion film forming process, the extrusion film forming process is usually carried out in an extruder, a proper amount of processing aid (such as plasticizer, slipping agent, lubricant and the like) can be added, the mixture is added into a screw for melting, the mixture is dispersed and mixed by the screw and then is output to a T die head, in order to reduce the orientation of the film, after the melt flows out of the T die head, auxiliary materials (such as release film or release paper and the like) with a certain thickness can be added to one surface of the film before a supercooling roller, and the film is rolled together after flattening and shaping. The type and amount of processing aids are typical of those currently available.

The vibrating diaphragm provided by the invention can form sound generating devices with any structure, such as the following typical two sound generating devices.

The sound generating device comprises a vibration system and a magnetic circuit system matched with the vibration system, wherein the vibration system comprises a vibrating diaphragm and a voice coil combined on one side of the vibrating diaphragm. When the sounding device works, the voice coil can vibrate up and down under the action of the magnetic field force of the magnetic circuit system after the voice coil is electrified so as to drive the vibrating diaphragm to vibrate, and sounding can be carried out when the vibrating diaphragm vibrates.

Another sound generating device can include the casing and establish magnetic circuit and vibration system in the casing, and vibration system can include voice coil loudspeaker voice coil, first vibrating diaphragm and second vibrating diaphragm, and the top of voice coil loudspeaker voice coil links to each other with first vibrating diaphragm, and magnetic circuit drives the voice coil loudspeaker voice coil vibration in order to drive first vibrating diaphragm sound production, and the both ends of second vibrating diaphragm link to each other with the bottom of casing and voice coil loudspeaker voice coil respectively. The second diaphragm may be a diaphragm according to the above embodiment of the present invention.

That is, the first diaphragm may be used for vibration sound production and the second diaphragm may be used for balancing the vibration of the voice coil. Specifically, when sound generating mechanism during operation, the voice coil is under magnetic field effect of magnetic circuit after the voice coil loudspeaker voice coil is circular telegram, and the voice coil loudspeaker voice coil can vibrate in order to drive first vibrating diaphragm vibration from top to bottom, can carry out the sound production when first vibrating diaphragm vibrates. The second vibrating diaphragm also can follow the upper and lower vibration of voice coil, because the both ends of second vibrating diaphragm link to each other with the bottom of casing and voice coil loudspeaker voice coil respectively, the vibration of voice coil loudspeaker voice coil can be balanced to the second vibrating diaphragm, can prevent that the voice coil loudspeaker voice coil from appearing the phenomenon of polarization to can promote sound production device's sound production effect.

It should be noted that the first diaphragm and the second diaphragm may be the diaphragms according to the above embodiments of the present invention, or one of the first diaphragm and the second diaphragm may be the diaphragm according to the above embodiments of the present invention, which is not particularly limited.

In conclusion, compared with the prior art, the vibrating diaphragm made of the thermoplastic polyester elastomer has the following technical effects.

(1) The service temperature range of the vibrating diaphragm is widened, and especially the low temperature resistance is improved: polyether and aliphatic polyester can form a better block structure with polynaphthalene dicarboxylic acid ester, so that lower glass transition temperature can be realized and low temperature resistance can be improved.

(2) The vibrating diaphragm provided by the invention has higher damping property: the naphthalene ring structure of the polynaphthalene dicarboxylic acid ester has larger rigidity, the steric hindrance of the molecular chain segment is larger than that of the benzene ring, and when the material is acted by external force, more external force can be consumed, so that the thermoplastic polyester elastomer has good damping property.

(3) The vibrating diaphragm has lower distortion, and at least can keep F0 and sensitivity which are equivalent to those of the existing vibrating diaphragm: by controlling the storage modulus and thickness of the thermoplastic polyester elastomer, the specificity of the recombination material can inhibit distortion and improve sensitivity.

(4) The preparation method is simple: the thermoplastic polyester elastomer can be prepared by adopting typical copolymerization, extrusion and other procedures.

(5) The use modes are more various, and the single-layer vibrating diaphragm or the composite vibrating diaphragm can be used.

The following is a detailed description of the embodiments.

Example 1

First, resin particles are produced

60 parts by mass of polybutylene naphthalate prepolymer with data molecular weight of 30000 and 40 parts by mass of polytetrahydrofuran ether with number average molecular weight of about 1000 are added into a reaction tank in inert gas atmosphere, 0.15 part by mass of n-butyl titanate is taken as a catalyst, 0.5 part by mass of polycarbodiimide stabilizer is added, the temperature is slowly raised to a molten state (230-265 ℃), the reaction is continued for about 1 hour until the resin becomes uniform transparent, and the resin is cut into particles by a slicer or granulator after being cooled, so that the film is manufactured.

Second, manufacturing the membrane material

Adopts a melt extrusion casting mode. Before film making, the particles are dried to remove water, then added into a screw for melting, dispersed and mixed by the screw and then output to a T die head, in order to reduce the orientation of the film, auxiliary materials (such as release film or release paper) with a certain thickness can be added to one surface of the film before a supercooling roller after the melt flows out of the T die head, and the film is rolled together after flattening and shaping. The difference of storage modulus of the obtained polycarbonate-polyester thermoplastic polyester elastomer film in the MD and TD directions is ensured to be about +/-5% -10% by controlling the speed of the vehicle, the pressure between cooling rollers and the like.

Comparative example

First, resin particles are produced

60 parts by mass of polybutylene terephthalate prepolymer with data molecular weight of 30000 and 40 parts by mass of polytetrahydrofuran ether with number average molecular weight of about 1000 are added into a reaction tank in inert gas atmosphere, 0.15 part by mass of n-butyl titanate is taken as a catalyst, 0.5 part by mass of polycarbodiimide is added, the temperature is slowly raised to a molten state (230-265 ℃), the reaction is continued for about 1 hour until the resin becomes uniform transparent, and the resin is cut into particles by a slicer or a granulator after being cooled, so that the resin is used for manufacturing a film.

Second, manufacturing the membrane material

Measuring the change of the loss modulus, the storage modulus and the loss factor of different thermoplastic polyester elastomer films with temperature

The testing method comprises the following steps: a flat rectangular spline with the width of 5-10 mm is adopted from the film by using a cutter or an art designer blade, and is tested by adopting the ASTM D412-2016 standard, the vibration frequency is 1Hz, and the heating rate is 3 ℃/min.

The results show that: as shown in fig. 1, the comparative example has a storage modulus similar to that of example 1 at room temperature, but the modulus of example 1 at high temperature is higher than that of the comparative example, which is an illustration of the more stable structural strength of the present invention at high temperature. The peak temperature of the loss modulus is the glass transition temperature of the material and represents the onset temperature of the high elastic state characteristics of the thermoplastic polyester elastomer material of the present invention. From the loss modulus versus temperature curve, the thermoplastic polyester elastomer films of the present invention have lower glass transition temperatures. In summary, the thermoplastic polyester elastomer film of the present invention has a wider range of use temperatures. As shown in fig. 2, example 1 of the present invention has higher damping (loss factor=loss modulus to storage modulus ratio of material).

Testing frequency response curve and total harmonic distortion curve of diaphragms made of different thermoplastic polyester elastomers

1. Manufacturing vibrating diaphragm

The thermoplastic polyester elastomer films in example 1 and comparative example were selected respectively to prepare diaphragms respectively. Wherein, the diaphragms in example 1 and comparative example all adopt three-layer composite structure, all include intermediate level and two top layers, the intermediate level is the acrylic acid glue film, two top layers are the thermoplastic polyester elastomer layer that corresponds respectively, and the thickness of intermediate level and two top layers is 20 mu m. That is, example 1 differs from the diaphragm in the comparative example only in the material of the thermoplastic polyester elastomer film layers of the two surface layers. The diaphragms in example 1 and comparative example were produced in the same manner as follows:

and (3) alternately superposing and pressing the prepared thermoplastic polyester elastomer film layer and the acrylic adhesive layer by adopting a compounding device to form a composite structure of the thermoplastic polyester elastomer film layer, the acrylic adhesive layer and the thermoplastic polyester elastomer film layer, thereby preparing the composite material belt with required collocation. And (3) placing the composite material belt on a hot press molding machine for secondary molding to prepare the required vibrating diaphragm shape, cutting the vibrating diaphragm shape to the product size, and assembling the vibrating diaphragm shape and the components such as a voice coil and a magnetic circuit system into a micro-speaker unit (shown in fig. 3 and 4).

2. The testing method comprises the following steps:

product performance tests were performed on micro Speakers (SPKs) equipped with diaphragms in the above example 1 and comparative example, respectively. The micro-speaker adopts the structure shown in fig. 3, and comprises a vibration system and a magnetic circuit system matched with the vibration system, wherein the vibration system comprises a vibrating diaphragm and a voice coil combined on one side of the vibrating diaphragm. The speaker vibration unit is shown in fig. 4, and a person skilled in the art can make corresponding adjustments according to actual product requirements. For example, as shown in fig. 3 and 4, the diaphragm 1 is composed of a folded ring portion 11 and a dome portion 12, and the thermoplastic polyester elastomer layer may be located on the folded ring portion 11 of the diaphragm, or may be located on the folded ring portion 11 and the dome portion 12. The ring-folding part 11 protrudes to the side far away from the voice coil 2; the ball top 12 is connected with the folded ring part 11; the centering support piece is arranged in the vibration system, so that the polarization resistance of the vibration system can be improved. The diaphragm 3 was composed of the thermoplastic polyester elastomers of example 2 and comparative example, respectively, each of which had a three-layer structure of "thermoplastic polyester elastomer film layer 31-subbing layer 32-thermoplastic polyester elastomer film layer 31", as shown in fig. 5.

The results show that: as shown in fig. 6 and 7, the comparative example has a similar storage modulus as the example, the assembled product has similar F0 and sensitivity (as shown by the frequency response curve), but the product of the invention has lower distortion (as shown by the total harmonic distortion curve).

The embodiments of the present disclosure are described above. However, these examples are for illustrative purposes only and are not intended to limit the scope of the present disclosure. The scope of the disclosure is defined by the appended claims and equivalents thereof. Various alternatives and modifications can be made by those skilled in the art without departing from the scope of the disclosure, and such alternatives and modifications are intended to fall within the scope of the disclosure.

Claims

1. A diaphragm for use in a sound emitting device, comprising:

a thermoplastic polyester elastomer film layer formed by copolymerizing a hard segment containing polynaphthalene dicarboxylic acid ester and a soft segment containing polyether and/or aliphatic polyester; the soft segments in the thermoplastic polyester elastomer film layer comprise polytetrahydrofuran ether;

2. A diaphragm according to claim 1, wherein the content of the hard segments in the thermoplastic polyester elastomer film layer is 30 to 80% by weight.

3. The diaphragm of claim 1 wherein the thermoplastic polyester elastomer film layer has a storage modulus of 50 to 500MPa at 23 ℃.

4. The diaphragm of claim 1, wherein the ratio of storage moduli in both MD and TD of the thermoplastic polyester elastomer film layer is 80-120:100.

5. The diaphragm of claim 1, wherein the diaphragm is of a single layer structure, and the diaphragm comprises only one layer of the thermoplastic polyester elastomer film.

6. The diaphragm of claim 1 wherein the diaphragm has a composite film structure in which at least one surface layer is the thermoplastic polyester elastomer film layer.

7. The diaphragm of claim 6 wherein the diaphragm is of the composite film structure with alternating layers of the thermoplastic polyester elastomer film and a glue layer, and both skin layers of the composite film structure are the thermoplastic polyester elastomer film layers.

8. A diaphragm according to claim 6 or 7, wherein each of the thermoplastic polyester elastomer film layers has a thickness of 5 to 50 μm.

9. The diaphragm of claim 7, wherein each of the layers of adhesive comprises one or more of a silicone layer, an acrylic layer;

and/or the thickness of each layer of the adhesive layer is 2-50 mu m.

10. The diaphragm of claim 7, wherein the glue layer has a glass transition temperature of less than or equal to-10 ℃.

11. The sound production device is characterized by comprising a vibration system and a magnetic circuit system matched with the vibration system, wherein the vibration system comprises a vibrating diaphragm and a voice coil combined on one side of the vibrating diaphragm, the magnetic circuit system drives the voice coil to vibrate so as to drive the vibrating diaphragm to produce sound, and the vibrating diaphragm is the vibrating diaphragm according to any one of claims 1-10.

12. The utility model provides a sound generating device, its characterized in that includes the casing and establishes 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, magnetic circuit drives the voice coil loudspeaker voice coil vibrates 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 the vibrating diaphragm according to any one of claims 1-10.