Sound production device and magnetic circuit system, and magnetically conductive thermosetting adhesive and preparation method thereof

Abstract

The application belongs to the technical field of electroacoustic, and particularly relates to a sound production device, a magnetic circuit system, a magnetic conductive thermosetting adhesive and a preparation method thereof. The magnetic conductive thermosetting adhesive comprises a thermosetting adhesive and a compounded magnetic conductive filler distributed in the thermosetting adhesive. The compounded magnetic conductive filler comprises a plurality of ferromagnetic powders with different particle sizes. On the basis of having magnetic conductive capacity, by adjusting the particle size distribution of the ferromagnetic powders, the powder bulk density is significantly improved, the resin voids are reduced, and the continuity and overall magnetic permeability of the magnetic conductive network are enhanced. Meanwhile, the grading structure in the application effectively improves the dispersion stability of the filler in the colloid through the space hindering effect between the particles, significantly slows down the sedimentation speed, increases the stability of the dispensing process and the actual service life of the glue.

Description

Technical Field

[0001] This application belongs to the field of electroacoustic technology, and specifically relates to a sound-generating device and magnetic circuit system, a magnetically conductive thermosetting adhesive, and a method for preparing the same. Background Technology

[0002] With the trend towards thinner and smaller speakers, pin-point adhesive bonding has become the mainstream process for magnetic circuit components. However, existing magnetic adhesives have obvious defects: First, the magnetic powder has a high density and is prone to settling. Settling in the later stages of use makes dispensing difficult, shortens the actual service life of the adhesive, and increases material consumption. Second, anti-settling agents such as silicon dioxide and aluminum oxide are added to solve the settling problem. Although this can improve the settling problem, it will seriously affect the inductance. At the same time, the price of the adhesive is relatively high, which further increases the production cost.

[0003] Therefore, existing loudspeakers and the adhesive materials used with them still need improvement. Summary of the Invention

[0004] The purpose of this application is to provide a sound-generating device and magnetic circuit system, as well as a magnetically conductive thermosetting adhesive and its preparation method. The magnetically conductive thermosetting adhesive provided in this application uses a mixture of ferromagnetic powders of various particle sizes to form a composite magnetically conductive filler. Based on its magnetic conductivity, by adjusting the particle size distribution of the ferromagnetic powders, the bulk density of the powder is significantly increased, and resin voids are reduced, thereby enhancing the continuity of the magnetic network and the overall magnetic permeability. Simultaneously, the gradation structure in this application effectively improves the dispersion stability of the filler in the colloid through the spatial obstruction effect between particles, significantly slows down the settling velocity, and increases the stability of the dispensing process and the actual service life of the adhesive.

[0005] The first aspect of this application provides a magnetically conductive thermosetting adhesive, comprising a thermosetting adhesive and a compound magnetically conductive filler distributed in the thermosetting adhesive. The compound magnetically conductive filler comprises a variety of ferromagnetic powders with different particle sizes, wherein the ferromagnetic powders include a first ferromagnetic powder, a second ferromagnetic powder, and a third ferromagnetic powder. The particle size of the first ferromagnetic powder is between 5 μm and 15 μm, the particle size of the second ferromagnetic powder is between 2 μm and 5 μm, and the particle size of the third ferromagnetic powder is between 0.1 μm and 2 μm. The compound magnetically conductive filler comprises at least two of the first ferromagnetic powder, the second ferromagnetic powder, and the third ferromagnetic powder.

[0006] In some embodiments of this application, the composite magnetic filler includes the first ferromagnetic powder, the second ferromagnetic powder, and the third ferromagnetic powder, wherein the first ferromagnetic powder accounts for 40% to 75% of the mass, the second ferromagnetic powder accounts for 20% to 50% of the mass, and the third ferromagnetic powder accounts for 5% to 40% of the mass.

[0007] In some embodiments of this application, the composite magnetic filler includes the first ferromagnetic powder, the second ferromagnetic powder, and the third ferromagnetic powder, wherein the first ferromagnetic powder accounts for 20% to 40% of the mass, the second ferromagnetic powder accounts for 40% to 70% of the mass, and the third ferromagnetic powder accounts for 5% to 40% of the mass.

[0008] In some embodiments of this application, the ferromagnetic powders of different particle sizes may be made of the same or different materials.

[0009] In some embodiments of this application, the ferromagnetic powder includes at least one of pure iron powder, iron-nickel alloy powder, and iron-cobalt alloy powder.

[0010] In some embodiments of this application, the thermosetting adhesive includes at least one of acrylate thermosetting adhesives, epoxy thermosetting adhesives, and anaerobic thermosetting adhesives.

[0011] In some embodiments of this application, the magnetically conductive thermosetting adhesive comprises the following components in parts by weight: The compound magnetic filler is 10-50 parts and the thermosetting adhesive is 50-90 parts.

[0012] In some embodiments of this application, the viscosity of the magnetic thermosetting adhesive is 14000 mp. . s~25000mp . s, specific saturation magnetization ≥50 emu / g, effective permeability ≥10.

[0013] The second aspect of this application also provides a method for preparing the magnetically conductive thermosetting adhesive described in the first aspect, comprising the following steps: obtaining a variety of ferromagnetic powders with different particle sizes and compounding them to obtain a compound magnetically conductive filler; the ferromagnetic powders include a first ferromagnetic powder, a second ferromagnetic powder, and a third ferromagnetic powder, wherein the particle size of the first ferromagnetic powder is between 5 μm and 15 μm, the particle size of the second ferromagnetic powder is between 2 μm and 5 μm, and the particle size of the third ferromagnetic powder is between 0.1 μm and 2 μm, and the compound magnetically conductive filler includes at least two of the first ferromagnetic powder, the second ferromagnetic powder, and the third ferromagnetic powder; mixing and stirring the compound magnetically conductive filler with the thermosetting adhesive to obtain the magnetically conductive thermosetting adhesive.

[0014] A third aspect of this application also provides a magnetic circuit system for a sound-generating device, comprising a magnetic yoke and a magnetic circuit assembly disposed on one side of the magnetic yoke. The magnetic circuit assembly includes a magnet and a magnetic plate, and the magnetic yoke, the magnet, and the magnetic plate are sequentially stacked along a first direction. The magnetic yoke and the magnet, and / or the magnet and the magnetic plate, are provided with the magnetic thermosetting adhesive described in the first aspect of this application, or with a magnetic thermosetting adhesive prepared using the preparation method described in the second aspect of this application.

[0015] In some embodiments of this application, the magnet includes a central magnet and side magnets spaced apart, and the magnetic guide plate includes a central magnetic guide plate and side magnetic guide plates. The central magnet and the central magnetic guide plate constitute a central magnetic part, and the side magnets and the side magnetic guide plates constitute a side magnetic part. The magnetic yoke, the central magnet, and the central magnetic guide plate are sequentially stacked along a first direction, and the central magnet and the magnetic yoke, and / or the central magnet and the central magnetic guide plate, are bonded together by the magnetic thermosetting adhesive.

[0016] In some embodiments of this application, the magnetic yoke, the side magnet, and the side magnetic plate are stacked sequentially along a first direction, and the side magnet and the magnetic yoke and / or the side magnet and the side magnetic plate are bonded together by the magnetic thermosetting adhesive.

[0017] The fourth aspect of this application also provides a sound-generating device, which includes the magnetic circuit system for the sound-generating device described in the third aspect of this application.

[0018] The magnetic thermosetting adhesive provided in this application employs a multi-particle-size ferromagnetic powder compounding scheme. On one hand, the multi-level particle size combination increases the powder bulk density, reduces resin voids, strengthens the continuity of the magnetic network, and effectively improves the overall magnetic permeability, ensuring the magnetic conductivity and acoustic performance of the sound-generating device. On the other hand, the gradation structure creates a spatial barrier effect between particles, significantly improving the dispersion stability of fillers in the adhesive system, significantly slowing down sedimentation, improving the stability of the needle dispensing process, and extending the actual service life of the magnetic thermosetting adhesive. Simultaneously, it eliminates the need for traditional anti-settling agents that affect inductance, thus balancing magnetic conductivity, process compatibility, and durability. Furthermore, the raw materials for the magnetic thermosetting adhesive in this application are readily available and low in cost.

[0019] The above description is only an overview of the technical solution of this application. In order to better understand the technical means of this application and to implement it in accordance with the contents of the specification, and to make the above and other objects, features and advantages of this application more obvious and understandable, the following are specific embodiments of this application. Attached Figure Description

[0020] To more clearly illustrate the technical solutions in the specific embodiments of this application or the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0021] Figure 1 This is a schematic diagram of the structure of a sound-generating device according to some embodiments of this application.

[0022] Explanation of reference numerals in the attached figures: 100 - Sound-generating device; 10-Housing; 20-Diaphragm assembly; 30-Magnetic yoke; 40-Center magnet; 50-Side magnet; 60-Center magnetic plate; 70-Side magnetic plate; 80-Magnetic thermosetting adhesive; 90-Voice coil. Detailed Implementation

[0023] Exemplary embodiments of this application will now be described in more detail with reference to the accompanying drawings. While exemplary embodiments of this application are shown in the drawings, it should be understood that this application may be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided to enable a more thorough understanding of this application and to fully convey the scope of this application to those skilled in the art.

[0024] It should be understood that the terminology used herein is for the purpose of describing particular exemplary embodiments only and is not intended to be limiting. Unless the context clearly indicates otherwise, the singular forms “a,” “an,” and “described” as used herein may also include the plural forms. The terms “comprising,” “including,” “containing,” and “having” are inclusive and therefore indicate the presence of the stated features, steps, operations, elements, and / or components, but do not exclude the presence or addition of one or more other features, steps, operations, elements, components, and / or combinations thereof. The method steps, processes, and operations described herein are not construed as requiring them to be performed in a particular order described or illustrated unless the order of performance is explicitly indicated. It should also be understood that additional or alternative steps may be used.

[0025] In the description of the embodiments of this application, technical terms such as "first" and "second" are used only to distinguish different objects and should not be construed as indicating or implying relative importance or implicitly specifying the number, specific order, or primary and secondary relationship of the indicated technical features. In the description of the embodiments of this application, "multiple" means two or more, unless otherwise explicitly defined.

[0026] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0027] In the description of the embodiments in this application, the term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, and B existing alone. Additionally, the character " / " in this document generally indicates that the preceding and following related objects have an "or" relationship.

[0028] In the description of the embodiments of this application, the term "multiple" refers to two or more (including two), similarly, "multiple sets" refers to two or more (including two sets), and "multiple pieces" refers to two or more (including two pieces).

[0029] The first aspect of this application provides a magnetically conductive thermosetting adhesive, which includes a thermosetting adhesive and a compound magnetically conductive filler distributed in the thermosetting adhesive. The compound magnetically conductive filler includes a variety of ferromagnetic powders with different particle sizes, wherein the ferromagnetic powders include a first ferromagnetic powder, a second ferromagnetic powder, and a third ferromagnetic powder. The particle size of the first ferromagnetic powder is between 5 μm and 15 μm, the particle size of the second ferromagnetic powder is between 2 μm and 5 μm, and the particle size of the third ferromagnetic powder is between 0.1 μm and 2 μm. The compound magnetically conductive filler includes at least two of the first ferromagnetic powder, the second ferromagnetic powder, and the third ferromagnetic powder.

[0030] In the embodiments of this application, the magnetic thermosetting adhesive contains a variety of ferromagnetic powders with different particle sizes. By combining multiple particle sizes, the packing density of the powder is increased, resin voids are reduced, the continuity of the magnetic network is strengthened, and the overall magnetic permeability is effectively improved, ensuring the magnetic conductivity and acoustic performance of the sound-generating device. Simultaneously, the gradation structure creates a spatial barrier effect between particles, significantly improving the dispersion stability of the filler, significantly slowing down the settling velocity, improving the stability of the needle dispensing process, and extending the service life of the magnetic thermosetting adhesive. Furthermore, it eliminates the need for traditional anti-settling agents that affect inductance, thus balancing magnetic conductivity, process compatibility, and durability.

[0031] In this embodiment of the application, the particle size of the first ferromagnetic powder is between 5 μm and 15 μm. For example, the particle size of the first ferromagnetic powder can be one of 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, 11 μm, 12 μm, 13 μm, 14 μm, and 15 μm, or any value that satisfies the above range.

[0032] In this embodiment of the application, the particle size of the second ferromagnetic powder is between 2 μm and 5 μm. For example, the particle size of the second ferromagnetic powder can be one of 2 μm, 3 μm, 4 μm, and 5 μm, or any value satisfying the above range.

[0033] In this embodiment of the application, the particle size of the third ferromagnetic powder is between 0.1 μm and 2 μm. For example, the particle size of the third ferromagnetic powder can be one of 0.1 μm, 0.2 μm, 0.4 μm, 0.5 μm, 0.6 μm, 0.8 μm, 1 μm, 1.2 μm, 1.4 μm, 1.5 μm, 1.6 μm, 1.8 μm, and 2 μm, or any value satisfying the above range.

[0034] By setting the particle sizes of the first, second, and third ferromagnetic powders within the aforementioned range, it is helpful to further increase the powder bulk density, reduce resin voids, and thus enhance the continuity of the magnetic network and the overall magnetic permeability. Simultaneously, the spatial obstruction effect between particles further improves the dispersion stability of the filler in the adhesive system, significantly slows down the settling velocity, enhances the stability of the dispensing process, and extends the actual service life of the adhesive.

[0035] In some embodiments of this application, a magnetic thermosetting adhesive can be used for bonding the magnetic circuit assembly of a cone loudspeaker, which is a large loudspeaker.

[0036] In some embodiments of this application, the compound magnetic filler includes a first ferromagnetic powder, a second ferromagnetic powder, and a third ferromagnetic powder, wherein the first ferromagnetic powder accounts for 40% to 75% of the mass, the second ferromagnetic powder accounts for 20% to 50% of the mass, and the third ferromagnetic powder accounts for 5% to 40% of the mass.

[0037] In the embodiments of this application, the cone speaker in car audio or headphones has a large volume, and the corresponding magnet volume also increases, resulting in a significant increase in the amount of adhesive used and the thickness of the adhesive layer at the bonding surface. To avoid obvious bonding defects at the bonding surface, it is necessary to ensure that the particle size of the filler particles is ≤ 1 / 2 of the adhesive layer thickness at the bonding position. Therefore, for the magnetic thermosetting adhesive used for bonding the magnetic circuit components of cone speakers, the ferromagnetic powder is mainly composed of coarse-grained first ferromagnetic powder, and its mass ratio is most suitable when controlled between 40% and 75%. When the mass ratio of the first ferromagnetic powder is less than 40%, there is insufficient large-particle skeleton powder in the system, the overall packing density is low, it is difficult to build a stable and continuous magnetic conductive path, the magnetic permeability drops significantly, and it cannot meet the high magnetic permeability requirements of the magnetic circuit. When the mass ratio of the first ferromagnetic powder is higher than 75%, the proportion of coarse-grained powder is too high, the adhesive bonding strength decreases, the fluidity deteriorates, and dispensing and molding become difficult. The optimal mass ratio of the second ferromagnetic powder is between 20% and 50%. When the mass ratio of the second ferromagnetic powder is less than 20%, it cannot effectively fill the gaps between coarse powder particles, resulting in large gaps in the powder arrangement, poor magnetic continuity, and low magnetic conduction efficiency. When the mass ratio of the second ferromagnetic powder exceeds 50%, it will encroach on the proportion space of the main coarse powder, disrupt the overall gradation structure, and destroy the balance of powder accumulation and arrangement. The optimal mass percentage of the third ferromagnetic powder is between 5% and 40%. When the mass percentage of the third ferromagnetic powder is less than 5%, there is too little fine filler powder, which cannot fill the tiny gaps between particles of each level. The powder density is insufficient, which not only limits the magnetic conductivity but also makes it difficult to suppress powder settling through particle barrier. When the mass percentage of the third ferromagnetic powder is greater than 40%, it will cause excessive accumulation of ultrafine powder, which is very easy to cause agglomeration. This will not only increase the overall viscosity of the adhesive and hinder normal dispensing operations but also disrupt the particle space barrier structure, thereby accelerating the powder settling speed and reducing the overall mechanical and adhesive stability of the adhesive after curing.

[0038] In some embodiments of this application, a magnetic thermosetting adhesive can be used for bonding of magnetic circuit components of a miniature loudspeaker.

[0039] In some embodiments of this application, the compound magnetic filler includes a first ferromagnetic powder, a second ferromagnetic powder, and a third ferromagnetic powder, wherein the first ferromagnetic powder accounts for 20% to 40% of the mass, the second ferromagnetic powder accounts for 40% to 70% of the mass, and the third ferromagnetic powder accounts for 5% to 40% of the mass.

[0040] In the embodiments of this application, for the small-sized miniature speakers in mobile phones or watches, the adhesive layer is thin, approximately 7 μm to 15 μm. Therefore, for the magnetically conductive adhesive used to bond the magnetic circuit components of the miniature speakers, the ferromagnetic powder is mainly composed of medium-particle second ferromagnetic powder, with its mass percentage controlled at 40% to 70%. This meets the requirements of the narrow bonding space of the miniature speakers, fully filling the main space of the adhesive layer and ensuring the core magnetic conductivity of the adhesive. When the mass percentage of the second ferromagnetic powder is less than 40%, the core ferromagnetic powder is missing, the overall permeability is significantly reduced, it cannot meet the magnetic flux conduction requirements of the magnetic circuit, and the bonding stability also deteriorates. Conversely, when the mass percentage of the second ferromagnetic powder is greater than 70%, the main powder is oversaturated, the resin binding component is insufficient, and the adhesive bonding strength decreases. The mass percentage of the first ferromagnetic powder should ideally be controlled between 20% and 40%. If the mass percentage is below 20%, the volume of large-diameter powder particles is insufficient, failing to form a stable particle support structure, resulting in insufficient overall packing density, incomplete magnetic conduction pathways, and poor magnetic transmission. Conversely, if the mass percentage is above 40%, it will encroach on the core particle powder ratio, disrupting the particle gradation system suitable for miniature speakers and causing poor flowability of the adhesive system. When the mass percentage of the third ferromagnetic powder is below 5%, fine gaps cannot be fully filled, resulting in numerous voids within the adhesive layer, weak magnetic continuity, and a significant reduction in anti-settling effect. Conversely, if the mass percentage is above 40%, excessive accumulation of ultrafine powder will easily lead to agglomeration, significantly increasing adhesive viscosity, hindering precise dispensing operations with micro-needles, disrupting particle layer arrangement, damaging the anti-settling structure, and accelerating powder settling, thus affecting the adhesive's lifespan and the quality of the bonded product.

[0041] In some embodiments of this application, the ferromagnetic powders of different particle sizes may be made of the same or different materials. It is understood that the magnetic thermosetting adhesive contains multiple ferromagnetic powders of different particle sizes, including a first ferromagnetic powder, a second ferromagnetic powder, and a third ferromagnetic powder. The first, second, and third ferromagnetic powders may be made of the same or different materials.

[0042] In some embodiments of this application, the ferromagnetic powder includes at least one of pure iron powder, iron-nickel alloy powder, and iron-cobalt alloy powder.

[0043] Specifically, the first ferromagnetic powder includes at least one of pure iron powder, iron-nickel alloy powder, and iron-cobalt alloy powder. The second ferromagnetic powder includes at least one of pure iron powder, iron-nickel alloy powder, and iron-cobalt alloy powder. The third ferromagnetic powder includes at least one of pure iron powder, iron-nickel alloy powder, and iron-cobalt alloy powder.

[0044] The aforementioned ferromagnetic powder possesses excellent inherent magnetic permeability and magnetic flux conduction capability, while exhibiting good chemical stability and excellent dispersion compatibility in adhesives. It can fully leverage the spatial barrier effect of particles, further delaying powder settling, stabilizing dispensing performance, and avoiding the adverse effects of adding additional anti-settling additives on inductance. It balances magnetic permeability, process stability, and adhesive durability.

[0045] In some embodiments of this application, the thermosetting adhesive includes at least one of acrylate thermosetting adhesives, epoxy thermosetting adhesives, and anaerobic thermosetting adhesives.

[0046] Thermosetting adhesives can be selected from any of the following types based on their curing method: acrylic thermosetting adhesives, epoxy thermosetting adhesives, and anaerobic thermosetting adhesives. Specifically, in practical applications, the appropriate type of adhesive can be selected according to the product reliability requirements of different magnetic circuit bonding positions in the sound-generating device. For example, the central magnet has a large bonding area and high weight, and its drop resistance requirements are more stringent during use. Therefore, an acrylic thermosetting adhesive or an anaerobic thermosetting adhesive with excellent elongation at break is selected. On the other hand, the side magnets have a smaller effective bonding area and are subject to the lateral attraction of the central magnet, requiring higher bonding strength. Therefore, an epoxy thermosetting adhesive with superior bonding performance is selected. Epoxy thermosetting adhesives have a higher modulus and a denser oxygen-free polymerization structure, making them suitable for side magnet positions with narrow bonding surfaces or lateral attraction.

[0047] In some embodiments of this application, the thermosetting adhesive is an acrylate thermosetting adhesive, which comprises the following components in parts by weight: 70 parts of acrylate oligomer, 30 parts of acrylate monomer, 5 parts of thermal initiator, and 0.5 parts of curing agent.

[0048] In embodiments of this application, the acrylate oligomer includes polyurethane acrylate oligomers.

[0049] In embodiments of this application, the acrylate monomers include a mixture of 4-hexanediol morpholine, hexanediol diacrylate, acrylic acid, and hydroxyethyl methacrylate.

[0050] In embodiments of this application, the thermal initiator includes at least one of azobisisobutyronitrile, cumene hydroperoxide, and benzoyl peroxide.

[0051] In the embodiments of this application, the curing agent is an acrylate monomer carrying special functional groups in the resin, which undergoes a chemical reaction during the reaction process to achieve further cross-linking of the resin network.

[0052] In some embodiments of this application, the thermosetting adhesive is an epoxy thermosetting adhesive, which comprises the following components in parts by weight: 100 parts of bisphenol A type epoxy resin, 64 parts of curing agent, 3 parts of accelerator, 1 part of thixotropic agent, and 1 part of antioxidant.

[0053] In embodiments of this application, the curing agent includes one of pentaerythritol tetra(3-mercaptopropionate), trimethylolpropane tri(3-mercaptopropionate), and ethoxylated trimethylolpropane tri(3-mercaptopropionate).

[0054] In the embodiments of this application, the accelerator includes one of DMP-30, triethylamine, and dimethylbenzylamine.

[0055] In embodiments of this application, the thixotropic agent comprises nanoscale fumed silica.

[0056] In embodiments of this application, the antioxidant includes antioxidant 1010.

[0057] In some embodiments of this application, the magnetically conductive thermosetting adhesive comprises the following components in parts by weight: The compound magnetic filler is 10-50 parts and the thermosetting adhesive is 50-90 parts.

[0058] By setting the weight ratio of the compounded magnetic filler and thermosetting adhesive as described above, a perfect balance between the magnetic conductivity and bonding / curing performance of the magnetic thermosetting adhesive can be achieved.

[0059] The compound magnetic filler provided in this application embodiment has a weight ratio of 10 to 50 parts. It is understood that if the weight ratio of the compound magnetic filler is less than 10 parts, the overall magnetic filler content is insufficient, the magnetic conductivity of the adhesive layer is significantly weakened, and the high magnetic permeability requirement of the magnetic circuit cannot be met, making it difficult for the acoustic performance of the sound-generating device to meet standards. Conversely, if the weight ratio of the compound magnetic filler is greater than 50 parts, the overall filler content is too high, which directly causes a significant increase in the viscosity of the thermosetting adhesive. Since the production of magnetic circuits for sound-generating devices generally uses needle-point dispensing, excessively high adhesive viscosity easily leads to problems such as poor dispensing and uneven dispensing. If the air pressure is deliberately increased to ensure normal dispensing, it can easily cause the adhesive tube to crack under pressure, affecting dispensing accuracy and production efficiency, increasing material consumption, and hindering stable production line processing. For example, the weight percentage of the compound magnetic filler can be one of 10 parts, 15 parts, 20 parts, 25 parts, 30 parts, 35 parts, 40 parts, 45 parts, or 50 parts, or any value within the range mentioned above.

[0060] The thermosetting adhesive provided in this application embodiment is in the range of 50 to 90 parts by weight. It is understood that when the thermosetting adhesive is less than 50 parts by weight, the matrix bonding component is insufficient, the adhesive layer has poor formability, the component bonding is easy to loosen and fall off, and the service life is shortened; while when the thermosetting adhesive is more than 90 parts by weight, the proportion of magnetic filler is excessively compressed, the overall magnetic conductivity of the adhesive layer drops sharply, it loses its core role of magnetic bonding, and cannot be adapted to the professional bonding application scenarios of magnetic circuit components of sound-generating devices.

[0061] In some embodiments of this application, the viscosity of the magnetic thermosetting adhesive is 14000 mp. . s~25000 mp . It is understandable that the viscosity of thermosetting adhesives is generally around 6000 mp. . s~12000 mp . Between 1 and 10 wt%, the increase in adhesive viscosity is more pronounced with the addition of magnetically conductive fillers of varying particle sizes. Even when the amount of the composite magnetically conductive filler is only about 10 wt%, the viscosity of the finished product increases significantly. When the proportion of the composite filler reaches nearly 50 wt%, the viscosity of the magnetically conductive thermosetting adhesive is close to 25,000 mp.s. Exceeding this limit, the adhesive becomes too thick, causing dispensing difficulties and hindering the precise application of adhesives to micro-devices, thus significantly reducing assembly efficiency and yield. For example, the viscosity of the magnetically conductive thermosetting adhesive can be 14,000 mp.s. . s, 15000 mp . s, 16000 mp . s, 17000 mp . s, 18000 mp . s, 19000 mp . s, 20000 mp . s, 21000 mp . s, 22000 mp . s, 23000 mp . s, 24000 mp . s, 25000 mp . s is one of the values ​​in s or any value that satisfies the above range.

[0062] It is worth mentioning that if the viscosity of the magnetic thermosetting adhesive changes by more than 20% from its initial value during use, it is determined that the adhesive cannot continue to be used normally. Based on this method, it is concluded that the service life of the magnetic thermosetting adhesive of this application embodiment is increased from 48 hours to 96 hours compared with conventional magnetic adhesives.

[0063] In some embodiments of this application, the specific saturation magnetization of the magnetic thermosetting adhesive is ≥50 emu / g, ensuring sufficient magnetic response capability and fully meeting the magnetic flux transmission requirements of the magnetic circuit. When the specific saturation magnetization of the magnetic thermosetting adhesive is below 50 emu / g, the adhesive's magnetism is too weak, failing to meet the high permeability standard for the sound-generating device's magnetic circuit. For example, the specific saturation magnetization of the magnetic thermosetting adhesive can be 50 emu / g, 60 emu / g, 70 emu / g, etc.

[0064] In some embodiments of this application, the effective permeability of the magnetic thermosetting adhesive is ≥10, which can significantly improve the overall magnetic flux conduction efficiency of the adhesive layer, reduce magnetic energy loss, and stabilize and optimize the acoustic output effect of the loudspeaker; when the effective permeability of the magnetic thermosetting adhesive is less than 10, the continuity of the magnetic conduction path of the adhesive layer is poor, the magnetic resistance is too large, and the improvement of high frequency loudness is not obvious.

[0065] By setting the viscosity, specific saturation magnetization, and effective permeability of the magnetic thermosetting adhesive within the above range, the stability of the dispensing process and the service life of the adhesive are increased, making it suitable for precision dispensing and bonding of magnetic circuits in miniature sound-generating devices.

[0066] The second aspect of this application provides a method for preparing a magnetically conductive thermosetting adhesive, thereby obtaining the magnetically conductive thermosetting adhesive described in the first aspect of this application.

[0067] In some embodiments of this application, the preparation method of the magnetic thermosetting adhesive is mainly carried out according to the following steps.

[0068] (1) Obtain ferromagnetic powders of different particle sizes and compound them to obtain compound magnetic fillers.

[0069] In some embodiments of this application, ferromagnetic powders of different particle sizes are weighed according to the mass ratio and filtered and screened to ensure that the particle size fluctuation of each powder is controllable.

[0070] In some embodiments of this application, the ferromagnetic powder includes a first ferromagnetic powder, a second ferromagnetic powder, and a third ferromagnetic powder. The particle size of the first ferromagnetic powder is between 5 μm and 15 μm, the particle size of the second ferromagnetic powder is between 2 μm and 5 μm, and the particle size of the third ferromagnetic powder is between 0.1 μm and 2 μm. The composite magnetic filler includes at least two of the first ferromagnetic powder, the second ferromagnetic powder, and the third ferromagnetic powder.

[0071] In some embodiments of this application, the compound magnetic filler includes a first ferromagnetic powder, a second ferromagnetic powder, and a third ferromagnetic powder, wherein the first ferromagnetic powder accounts for 40% to 75% of the mass, the second ferromagnetic powder accounts for 20% to 50% of the mass, and the third ferromagnetic powder accounts for 5% to 40% of the mass.

[0072] In some embodiments of this application, the compound magnetic filler includes a first ferromagnetic powder, a second ferromagnetic powder, and a third ferromagnetic powder, wherein the first ferromagnetic powder accounts for 20% to 40% of the mass, the second ferromagnetic powder accounts for 40% to 70% of the mass, and the third ferromagnetic powder accounts for 5% to 40% of the mass.

[0073] In some embodiments of this application, the ferromagnetic powder includes at least one of pure iron powder, iron-nickel alloy powder, and iron-cobalt alloy powder.

[0074] (2) The compound magnetic filler and thermosetting adhesive are mixed and stirred, and after standing and filling, the bubbles are degassed to obtain the magnetic thermosetting adhesive.

[0075] In some embodiments of this application, the thermosetting adhesive includes at least one of acrylate thermosetting adhesives, epoxy thermosetting adhesives, and anaerobic thermosetting adhesives.

[0076] In the embodiments of this application, the prepared magnetic thermosetting adhesive needs to be stored at -20°C away from light to ensure that the particle size of the magnetic thermosetting adhesive is ≤50 μm.

[0077] It is worth mentioning that, in the embodiments of this application, the particle size of the magnetically conductive thermosetting adhesive is ≤50 μm and not 0. In some embodiments of this application, the particle size of the magnetically conductive thermosetting adhesive is 15 μm to 50 μm. Exemplarily, the particle size of the magnetically conductive thermosetting adhesive can be one of 0.1 μm, 0.2 μm, 0.5 μm, 0.8 μm, 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, 15 μm, 20 μm, 25 μm, 30 μm, 35 μm, 40 μm, 45 μm, 50 μm or any value satisfying the above range.

[0078] A third aspect of this application also provides a magnetic circuit system for a sound-generating device, combined with... Figure 1 The sound-generating device 100 includes a housing 10 and a vibration system and a magnetic circuit system disposed inside the housing 10. The vibration system includes a diaphragm assembly 20 and a voice coil 90; the magnetic circuit system includes a magnetic yoke 30 and a magnetic circuit assembly disposed on one side of the magnetic yoke 30, the magnetic circuit assembly including a magnet and a magnetic plate, the magnetic yoke, magnet, and magnetic plate being sequentially stacked along a first direction; wherein, a magnetically conductive thermosetting adhesive 80 as described in the first aspect of this application is disposed between the magnetically conductive yoke and the magnet and / or between the magnet and the magnetic plate, or a magnetically conductive thermosetting adhesive 80 prepared using the preparation method described in the second aspect of this application is disposed.

[0079] In some embodiments of this application, the magnet includes a central magnet 40 and a side magnet 50 spaced apart, and the magnetic guide plate includes a central magnetic guide plate 60 and a side magnetic guide plate 70. The central magnet 40 and the central magnetic guide plate 60 constitute a central magnetic part, and the side magnet 50 and the side magnetic guide plate 70 constitute a side magnetic part. The magnetic yoke 30, the central magnet 40 and the central magnetic guide plate 60 are stacked sequentially along a first direction, and the central magnet 40 and the magnetic yoke 30 and / or the central magnet 40 and the central magnetic guide plate 60 are bonded together by a magnetic thermosetting adhesive 80.

[0080] In some embodiments of this application, the magnetic yoke 30, the side magnet 50 and the side magnetic plate 70 are stacked sequentially along a first direction, and the side magnet 50 and the magnetic yoke 30 and / or the side magnet 50 and the side magnetic plate 70 are bonded together by a magnetic thermosetting adhesive 80.

[0081] The fourth aspect of this application also provides a sound-generating device, which includes the magnetic circuit system for the sound-generating device described in the fourth aspect of this application.

[0082] In embodiments of this application, the sound-generating device may be a miniature loudspeaker.

[0083] Unless otherwise defined, the technical terms used in the following embodiments have the same meaning as commonly understood by those skilled in the art to which this application pertains. Unless otherwise specified, the experimental reagents used in the following embodiments are all conventional biochemical reagents; the raw materials, instruments, and equipment used in the following embodiments can all be obtained through commercial purchase or by existing methods; the amounts of experimental reagents used are, unless otherwise specified, the amounts used in conventional experimental operations; and the experimental methods used are, unless otherwise specified, conventional methods. It should be further noted that the following descriptions are merely exemplary and not intended to limit the scope of this application. Moreover, the comparative examples below are selected to compare with the technical solutions of this application to demonstrate the advancement of the technical solutions of this application, and do not necessarily represent prior art in this technical field.

[0084] Example 1 This embodiment 1 provides a magnetic thermosetting adhesive and a miniature loudspeaker using the magnetic thermosetting adhesive. The magnetic thermosetting adhesive is used to bond the center magnet and the side magnet of the miniature loudspeaker. The magnetic thermosetting adhesive includes the following components by weight: 50 parts of thermosetting adhesive and 50 parts of compound magnetic filler.

[0085] The composite magnetic filler includes a first iron-nickel alloy powder, a second iron-nickel alloy powder, and a third iron-nickel alloy powder. The particle size of the first iron-nickel alloy powder is 6 μm, the particle size of the second iron-nickel alloy powder is 4 μm, and the particle size of the third iron-nickel alloy powder is 2 μm. The mass percentage of the first iron-nickel alloy powder is 20%, the mass percentage of the second iron-nickel alloy powder is 70%, and the mass percentage of the third iron-nickel alloy powder is 10%.

[0086] The thermosetting adhesive is an acrylate thermosetting adhesive, comprising the following components by weight: 70 parts acrylate oligomer, 30 parts acrylate monomer, 5 parts thermal initiator, and 0.5 parts curing agent. The acrylate oligomer is a polyurethane acrylate oligomer, and the acrylate monomer is a mixture of 4-benzoylmorpholine, hexanediol diacrylate, acrylic acid, and hydroxyethyl methacrylate. The thermal initiator is a mixture of azobisisobutyronitrile, cumene hydroperoxide, and benzoyl peroxide. The curing agent is an acrylate monomer carrying special functional groups in the resin, which undergoes a chemical reaction during the reaction process to further crosslink the resin network.

[0087] The preparation method of this magnetically conductive thermosetting adhesive includes the following steps: S1: Add acrylate oligomer, acrylate monomer, thermal initiator, and curing agent according to the formula, mix and stir, allow to stand, fill and degas to obtain acrylate thermosetting adhesive. Store the prepared acrylate thermosetting adhesive at -20℃ in the dark. The particle size of the acrylate thermosetting adhesive is ≤50 μm and not 0.

[0088] S2: Weigh iron-nickel alloy powders of different particle sizes according to the mass ratio, filter and screen them, and then mix them to obtain a composite magnetic filler.

[0089] S3: Add acrylate thermosetting adhesive and compounded magnetic filler according to the formula, mix and stir, let stand and fill, and then degas to obtain magnetic thermosetting adhesive. Store the prepared magnetic thermosetting adhesive at -20℃ in the dark. The particle size of the magnetic thermosetting adhesive is ≤50 μm and not 0.

[0090] Example 2 This embodiment 2 discloses a magnetic thermosetting adhesive and a cone loudspeaker using the magnetic thermosetting adhesive. The magnetic thermosetting adhesive is used to bond the center magnet and the side magnet of the cone loudspeaker. The magnetic thermosetting adhesive includes the following components by weight: 50 parts of thermosetting adhesive and 50 parts of compound magnetic filler.

[0091] The composite magnetic filler includes a first iron-nickel alloy powder, a second iron-nickel alloy powder, and a third iron-nickel alloy powder. The particle size of the first iron-nickel alloy powder is 10 μm, the particle size of the second iron-nickel alloy powder is 4 μm, and the particle size of the third iron-nickel alloy powder is 2 μm. The mass percentage of the first iron-nickel alloy powder is 60%, the mass percentage of the second iron-nickel alloy powder is 30%, and the mass percentage of the third iron-nickel alloy powder is 10%.

[0092] The thermosetting adhesive is a two-component acrylate thermosetting adhesive, comprising the following components by weight: 70 parts acrylate oligomer, 30 parts acrylate monomer, 5 parts thermal initiator, and 0.5 parts accelerator. The acrylate oligomer is a polyurethane acrylate oligomer, and the acrylate monomer is a mixture of 4-benzoylmorpholine, hexanediol diacrylate, acrylic acid, and hydroxyethyl methacrylate. The thermal initiator is a mixture of azobisisobutyronitrile, cumene hydroperoxide, and benzoyl peroxide. The curing agent is an acrylate monomer carrying special functional groups in the resin, which undergoes a chemical reaction during the reaction process to further crosslink the resin network.

[0093] The preparation method of the magnetic thermosetting adhesive in Example 2 is the same as that in Example 1.

[0094] Comparative Example 1 The only difference between Comparative Example 1 and Example 1 is that the ferromagnetic powder used in the magnetic thermosetting adhesive in Comparative Example 1 was not particle size-graded, and iron-nickel alloy powder with the same particle size of 5 μm was selected.

[0095] Comparative Example 2 The difference between Comparative Example 2 and Example 2 is that Comparative Example 2 uses a thermosetting adhesive without added composite magnetic filler and selects iron-nickel alloy powder with the same particle size of 10 μm.

[0096] Performance testing 1. Particle size test.

[0097] The particle size of the powder was tested using a scraper fineness meter.

[0098] 2. Viscosity test.

[0099] The viscosity of the magnetic thermosetting adhesive was tested using a 52z rotor and a cone-plate viscometer with a temperature controlled at 25℃.

[0100] 3. Specific saturation magnetization test.

[0101] Using a vibrating sample magnetometer, a cured thermosetting adhesive was prepared into a cured sample block with dimensions of 1 cm × 1 cm × 1 mm. The sample block was placed in a constant magnetic field of -10000 Oe to 10000 Oe, and the MH curve was obtained to obtain the specific saturation magnetization of the sample block.

[0102] 4. Effective magnetic permeability test of the cured magnetic thermosetting adhesive.

[0103] The effective permeability (μ) of the cured sample was tested using a toroidal sample combined with impedance analysis. eff ).

[0104] 5. Test the thickness of the adhesive layer at the bonding interface.

[0105] Thickness was measured using a super depth-of-field 3D microscope.

[0106] The magnetic thermosetting adhesives prepared in the examples and comparative examples were subjected to corresponding performance tests, and the test results are detailed in Table 1.

[0107] Table 1

[0108] As can be seen from the test results in Table 1, the quality and type of magnetic filler added in Examples 1-2 and Comparative Examples 1-2 are consistent. Therefore, the specific saturation magnetization of the thermosetting adhesives of the same mass after curing is almost the same. However, the advantage of Examples 1-2 lies in the use of multi-stage compounded magnetic powder, which increases the contact probability between powders, enhances the continuity of the magnetic network and the overall magnetic permeability. At the same time, this graded structure effectively improves the dispersion stability of the filler in the colloid through the spatial obstruction effect between particles, significantly slows down the settling speed, increases the stability of the dispensing process and the actual service life of the adhesive. At the application temperature of 25℃, the online use time of conventional thermosetting adhesives is extended from 48 h to 96 h, thus overcoming the problems of easy settling of magnetic powder in existing magnetic adhesives, shorter adhesive use time, increased scrap rate, increasing difficulty in line application, difficulty in controlling adhesive amount, and increased product defect rate.

[0109] Meanwhile, comparing Examples 1 and 2, the particle size distribution of the three-stage graded magnetic filler was changed. It can be seen that the larger the particle size, the smaller the specific surface area, and the weaker the friction and interaction between the particles and the binder. The viscosity of Example 2 will also decrease accordingly. It can also be concluded that the filling ratio of the magnetic filler is the same in Examples 1 and 2, but the contact efficiency between the ferromagnetic powders of various particle sizes in Example 1 is higher, the resin voids are smaller, and the effective magnetic permeability obtained by the test is also higher.

[0110] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

Claims

1. A magnetically conductive thermosetting adhesive, characterized in that, It includes a thermosetting adhesive and a compound magnetic filler distributed in the thermosetting adhesive, wherein the compound magnetic filler comprises ferromagnetic powders of various particle sizes. The ferromagnetic powder comprises a first ferromagnetic powder, a second ferromagnetic powder, and a third ferromagnetic powder. The particle size of the first ferromagnetic powder is between 5 μm and 15 μm, the particle size of the second ferromagnetic powder is between 2 μm and 5 μm, and the particle size of the third ferromagnetic powder is between 0.1 μm and 2 μm. The composite magnetic filler comprises at least two of the first ferromagnetic powder, the second ferromagnetic powder, and the third ferromagnetic powder.

2. The magnetically conductive thermosetting adhesive as described in claim 1, characterized in that, The composite magnetic filler comprises the first ferromagnetic powder, the second ferromagnetic powder, and the third ferromagnetic powder. The first ferromagnetic powder accounts for 40% to 75% of the mass, the second ferromagnetic powder accounts for 20% to 50% of the mass, and the third ferromagnetic powder accounts for 5% to 40% of the mass.

3. The magnetically conductive thermosetting adhesive as described in claim 1, characterized in that, The composite magnetic filler comprises the first ferromagnetic powder, the second ferromagnetic powder, and the third ferromagnetic powder. The first ferromagnetic powder accounts for 20% to 40% of the mass, the second ferromagnetic powder accounts for 40% to 70% of the mass, and the third ferromagnetic powder accounts for 5% to 40% of the mass.

4. The magnetically conductive thermosetting adhesive as described in claim 1, characterized in that, The ferromagnetic powders of different particle sizes may be made of the same or different materials; And / or, the ferromagnetic powder includes at least one of pure iron powder, iron-nickel alloy powder, and iron-cobalt alloy powder.

5. The magnetically conductive thermosetting adhesive as described in any one of claims 1 to 4, characterized in that, The thermosetting adhesive includes at least one of acrylate thermosetting adhesives, epoxy thermosetting adhesives, and anaerobic thermosetting adhesives.

6. The magnetically conductive thermosetting adhesive as described in any one of claims 1 to 4, characterized in that, Includes the following components by weight: The compound magnetic filler is 10-50 parts and the thermosetting adhesive is 50-90 parts.

7. The magnetically conductive thermosetting adhesive according to any one of claims 1 to 4, characterized in that, The viscosity of the magnetic thermosetting adhesive is 14000 mp. . s~25000 mp . s, specific saturation magnetization ≥50 emu / g, effective permeability ≥10.

8. A method for preparing a magnetically conductive thermosetting adhesive according to any one of claims 1 to 7, characterized in that, Includes the following steps: A composite magnetic filler is obtained by obtaining ferromagnetic powders of various particle sizes and compounding them; the ferromagnetic powders include a first ferromagnetic powder, a second ferromagnetic powder, and a third ferromagnetic powder, wherein the particle size of the first ferromagnetic powder is between 5 μm and 15 μm, the particle size of the second ferromagnetic powder is between 2 μm and 5 μm, and the particle size of the third ferromagnetic powder is between 0.1 μm and 2 μm; the composite magnetic filler includes at least two of the first ferromagnetic powder, the second ferromagnetic powder, and the third ferromagnetic powder. The magnetically conductive filler is mixed and stirred with a thermosetting adhesive to obtain the magnetically conductive thermosetting adhesive.

9. A magnetic circuit system for a sound-generating device, characterized in that, The device includes a magnetic yoke and a magnetic circuit assembly disposed on one side of the magnetic yoke. The magnetic circuit assembly includes a magnet and a magnetic plate. The magnetic yoke, the magnet, and the magnetic plate are stacked sequentially along a first direction. The magnetic yoke and the magnet and / or the magnet and the magnetic plate are provided with a magnetic thermosetting adhesive as described in any one of claims 1 to 7, or with a magnetic thermosetting adhesive prepared by the preparation method described in claim 8.

10. The magnetic circuit system for a sound-generating device as described in claim 9, characterized in that, The magnet includes a central magnet and side magnets spaced apart, and the magnetic guide plate includes a central magnetic guide plate and side magnetic guide plates. The central magnet and the central magnetic guide plate constitute a central magnetic part, and the side magnets and the side magnetic guide plates constitute a side magnetic part. The magnetic yoke, the central magnet, and the central magnetic plate are stacked sequentially along a first direction, and the central magnet and the magnetic yoke and / or the central magnet and the central magnetic plate are bonded together by the magnetic thermosetting adhesive. And / or, the magnetic yoke, the side magnet and the side magnetic plate are stacked sequentially along the first direction, and the side magnet and the magnetic yoke and / or the side magnet and the side magnetic plate are bonded together by the magnetic thermosetting adhesive.

11. A sound-generating device, characterized in that, Includes the magnetic circuit system for the sound-generating device as described in claim 9 or 10.

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