Conductive diaphragm and loudspeaker

Abstract

The application provides a conductive diaphragm and a loudspeaker. The conductive diaphragm comprises a main body layer and a conductive layer arranged on the main body layer, the conductive layer comprises an elastic matrix and a conductive filler dispersed in the elastic matrix, and the composition of the conductive layer is as follows: the elastic matrix is 8-20 parts, the conductive filler is 76-95 parts, and a modifier is 0.1-3 parts. The conductive filler comprises a nano metal conductive filler and a micro-nano conductive filler. Compared with the prior art, the conductive layer of the conductive diaphragm has good modulus stability at high and low temperatures, the nano metal conductive filler with a melting point lower than 200 DEG C is blended with the micro-nano conductive filler as a conductive functional body, the conductive functional bodies in the conductive layer are fused with each other to form a stable conductive network, and the elastic matrix can effectively avoid problems such as sudden change of rigidity of the conductive diaphragm and poor material toughness, so that the conductivity and smoothness are considered.

Description

Conductive diaphragm and loudspeaker Technical Field

[0001] This invention relates to the field of electroacoustic conversion, and more particularly to a conductive diaphragm and a loudspeaker. Background Technology

[0002] A loudspeaker typically consists of a diaphragm, a voice coil, and conductive lines connecting the voice coil to external circuitry. The voice coil leads are usually spot-welded to pads on the external conductive lines, and the diaphragm produces sound through electrical signals controlled by the loudspeaker. However, when the pads are connected to the voice coil leads, high-frequency vibrations and stress concentration can cause the voice coil leads to break, leading to loudspeaker failure. While adding an FPC (flexible printed circuit board) as an external circuit connection device can partially solve the voice coil breakage problem in existing loudspeakers, it occupies internal space and reduces loudspeaker performance. Creating a conductive layer on the diaphragm surface not only effectively solves the voice coil breakage problem but also does not occupy internal space, effectively improving the loudspeaker's reliability and acoustic performance.

[0003] The conductive circuit layer on the diaphragm surface can be created by spraying or printing a conductive layer. This conductive layer mainly consists of a resin matrix and conductive materials. Its conductivity is achieved by filling the diaphragm with conductive particles, allowing them to contact each other and form conductive pathways. To reduce the resistance of the conductive layer, the mass percentage of conductive material in the polymer matrix is ​​often increased. However, increasing the mass percentage of conductive material reduces the diaphragm's toughness, and the conductive pathways formed by the added conductive material are unstable. When the material is stretched or subjected to strain, the resistance of the conductive layer increases significantly, failing to meet the conductivity requirements of the conductive diaphragm.

[0004] There are two existing technologies to address the above problems. One approach involves compounding conductive particles of different types or sizes, filling the spaces between micron-sized conductive fillers with nano-sized fillers, and utilizing the tunneling effect to create a low-resistivity conductive layer. However, this conductive layer still cannot solve the problem of a sharp increase in resistance during diaphragm vibration, i.e., under material tension. The second approach involves adding a large number of silver nanowires to reduce the resistance change under material tension. This method is not only very expensive, but also causes severe deformation of the conductive layer during hot pressing, easily leading to open circuits in the conductive layer and a significant increase in speaker distortion.

[0005] Therefore, how to solve the problem of a significant increase in resistance during the vibration of the conductive layer, and how to prevent the conductive layer from affecting the vibration of the diaphragm and reducing sound quality, is an urgent issue to be addressed. It is necessary to provide a new conductive diaphragm and loudspeaker to solve the above-mentioned technical problems. Summary of the Invention

[0006] The purpose of this invention is to provide a conductive diaphragm and loudspeaker that balances conductivity and smoothness.

[0007] To achieve the above objectives, in a first aspect, the present invention provides a conductive diaphragm, the conductive diaphragm comprising a main body layer and a conductive layer disposed on the surface of the main body layer, the conductive layer comprising an elastic matrix and conductive fillers dispersed in the elastic matrix;

[0008] The conductive layer comprises, by mass ratio: 8-20 parts of the elastic matrix, 76-95 parts of the conductive filler, and 0.1-3 parts of the modifier;

[0009] The conductive filler includes nano-metal conductive fillers and micro-nano conductive fillers;

[0010] The diameter of the nano-metal conductive filler is 3-40 nm, and the diameter of the micro-nano conductive filler is 0.2-9 μm;

[0011] The weight ratio of the nano-metal conductive filler to the micro-nano conductive filler is 0.3:10 - 6:10;

[0012] The melting point of the nano-metal conductive filler is below 200℃.

[0013] Preferably, the initial resistivity of the conductive layer is The elastic modulus of the conductive layer is 5-400 MPa, and the elongation at break of the conductive layer is >100%; when the strain of the conductive diaphragm is ≤25%, the resistance change rate of the conductive diaphragm is ≤450%.

[0014] Preferably, the nano-metal conductive filler includes one or more of silver, gold, copper, aluminum, nickel, vanadium, indium, and palladium.

[0015] Preferably, the shape of the micro / nano conductive filler includes one or more of the following: spherical, near-spherical, sheet-like, dendritic, and rod-like.

[0016] Preferably, the micro / nano conductive filler includes one or more of metallic materials, surface-plated metallic materials, and conductive carbon materials.

[0017] Preferably, the metallic material includes one or more of silver, gold, copper, aluminum, nickel, vanadium, indium, and palladium.

[0018] Preferably, the surface metallization material includes one or more of silver-plated copper and silver-plated polymer particles.

[0019] Preferably, the conductive carbon material includes one or more of carbon black, graphene, and carbon nanotubes.

[0020] Preferably, the elastic matrix includes one or more of the following: silicone elastomer, acrylate rubber, ethylene acrylate rubber, nitrile rubber, hydrogenated nitrile rubber, butyl rubber, ethylene propylene rubber, and thermoplastic elastomer.

[0021] Preferably, the modifier includes one or more of the following: leveling agent, defoamer, conductivity promoter, thixotropic agent, and dispersant.

[0022] Preferably, the conductive layer is formed on one side of the surface of the main body layer or on both opposite sides, and completely covers the surface of the main body layer; or the conductive layer is at least partially embedded in one side of the main body layer.

[0023] Preferably, the conductive layer is coated or adhered to the main body layer, or the conductive layer and the main body layer are integrally injection molded.

[0024] In a second aspect, the present invention also provides a loudspeaker, the loudspeaker comprising the conductive diaphragm described in any of the above embodiments.

[0025] Compared with the prior art, the conductive layer of the conductive diaphragm of the present invention uses an elastomer with good high and low temperature modulus stability as the elastic matrix, and blends nano-metal conductive fillers with a melting point below 200°C with micro-nano conductive fillers as conductive functional bodies. The conductive functional bodies are compounded with modifiers to prepare a stretchable conductive slurry. When the nano-metal conductive fillers in the conductive slurry volatilize or vulcanize, partial melting will occur, thereby fusing the various conductive functional bodies in the conductive layer to form a stable conductive network. The elastic matrix with good high and low temperature modulus stability can effectively avoid problems such as sudden rigidity changes and poor material toughness of the conductive diaphragm, thus achieving a balance between conductivity and smoothness. Attached Figure Description

[0026] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort, wherein:

[0027] Figure 1 is a schematic diagram of the structure of the conductive diaphragm provided in an embodiment of the present invention;

[0028] Figure 2 is a schematic diagram of the structure of the conductive diaphragm provided in an embodiment of the present invention;

[0029] Figure 3 is a schematic diagram of the structure of the conductive diaphragm provided in an embodiment of the present invention.

[0030] In the diagram, 100 is the conductive diaphragm, 101 is the main body layer, and 102 is the conductive layer. Detailed Implementation

[0031] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0032] Referring to Figures 1-3, the present invention provides a conductive diaphragm 100, the conductive diaphragm 100 including a main body layer 101 and a conductive layer 102 disposed on the surface of the main body layer 101, the conductive layer 102 including an elastic matrix and conductive fillers dispersed in the elastic matrix;

[0033] The conductive layer 102 is composed of the following components by mass ratio: 8-20 parts of the elastic matrix, 76-95 parts of the conductive filler, and 0.1-3 parts of the modifier.

[0034] The initial resistivity of the conductive layer 102 is The elastic modulus of the conductive layer 102 is 5-400 MPa, and the elongation at break of the conductive layer 102 is >100%; when the strain of the conductive diaphragm 100 is ≤25%, the resistance change rate of the conductive diaphragm 100 is ≤450%.

[0035] In this invention, the conductive filler includes nano-metal conductive filler and micro-nano conductive filler;

[0036] The diameter of the nano-metal conductive filler is 3-40 nm, and the diameter of the micro-nano conductive filler is 0.2-9 μm;

[0037] The weight ratio of the nano-metal conductive filler to the micro-nano conductive filler is 0.3:10 - 6:10.

[0038] In this invention, the nano-metal conductive filler includes one or more of silver, gold, copper, aluminum, nickel, vanadium, indium, and palladium.

[0039] In this invention, the melting point of the nano-metal conductive filler is below 200°C.

[0040] In this invention, the shape of the micro-nano conductive filler includes one or more of the following: spherical, near-spherical, sheet-like, dendritic, and rod-like.

[0041] In this invention, the micro-nano conductive filler includes one or more of the following: metallic materials, surface-plated metallic materials, and conductive carbon materials.

[0042] In this invention, the metallic material includes one or more of silver, gold, copper, aluminum, nickel, vanadium, indium, and palladium.

[0043] In this invention, the surface metallization material includes one or more of silver-plated copper and silver-plated polymer particles.

[0044] In this invention, the conductive carbon material includes one or more of carbon black, graphene, and carbon nanotubes.

[0045] In this invention, the elastic matrix includes one or more of the following: silicone elastomers, acrylate rubbers, ethylene acrylate rubbers, nitrile rubbers, hydrogenated nitrile rubbers, butyl rubbers, ethylene propylene rubbers, and thermoplastic elastomers.

[0046] In this invention, the modifier includes one or more of the following: leveling agent, defoamer, conductivity promoter, thixotropic agent, and dispersant.

[0047] In this invention, the conductive layer 102 is formed on one side of the surface of the main body layer 101 or on both opposite sides, and completely covers the surface of the main body layer 101; or the conductive layer 102 is at least partially embedded in one side of the main body layer 101. In another optional embodiment, the conductive layer 102 is coated or adhered to the main body layer 101, or the conductive layer 102 and the main body layer 101 are integrally injection molded.

[0048] Compared with the prior art, the conductive layer of the conductive diaphragm of the present invention uses an elastomer with good high and low temperature modulus stability as the elastic matrix, and blends nano-metal conductive fillers with a melting point below 200°C with micro-nano conductive fillers as conductive functional bodies. The conductive functional bodies are compounded with modifiers to prepare a stretchable conductive slurry. When the nano-metal conductive fillers in the conductive slurry volatilize or vulcanize, partial melting occurs, thereby fusing the various conductive functional bodies in the conductive layer to form a stable conductive network. The elastic matrix with good high and low temperature modulus stability can effectively avoid problems such as sudden rigidity changes and poor material toughness of the conductive diaphragm, and reduce the resistance change of the diaphragm under stretching, thereby achieving a balance between conductivity and smoothness.

[0049] In order to better demonstrate the performance test of the conductive diaphragm 100 of the present invention, the following Examples 1, 2, and comparative examples were made to obtain measurement results.

[0050] Example 1

[0051] Preparation process of conductive diaphragm: 15 parts of butyl rubber were added to 40 parts of ethylene glycol butyl ether and stirred at high speed to dissolve. Then, 0.8 parts of leveling agent BYK-410, 0.5 parts of dispersant BYK-110, 0.5 parts of thixotropic agent BYK-607, 10 parts of nano silver powder (particle size D50 15nm, nano-metal conductive filler), and 75 parts of flake silver powder (D50 3μm, micro-nano conductive filler) were added sequentially and stirred thoroughly to form a mixed slurry. The mixed slurry was then stirred evenly using a dual planetary mixer. Finally, after high-speed dispersion and degassing, a conductive silver paste with a viscosity of 10300cps was obtained. The silver paste was transferred onto the diaphragm by screen printing or diluted inkjet printing (including aerosol jet printing). Then, it was baked at 150℃ for 15 minutes to a thickness of 50±2μm and cut into sections. Spline, used to test the change in resistance of the diaphragm before and after stretching.

[0052] Example 2

[0053] Preparation process of conductive diaphragm: 15 parts of butyl rubber were added to 40 parts of ethylene glycol butyl ether and stirred at high speed to dissolve. Then, 0.8 parts of leveling agent BYK-410, 0.5 parts of dispersant BYK-110, 0.5 parts of thixotropic agent BYK-607, 15 parts of nano silver powder (particle size D50 15nm), and 70 parts of flake silver powder (D50 3μm) were added sequentially and stirred thoroughly to form a mixed slurry. The mixed slurry was then stirred evenly using a dual planetary mixer. Finally, after high-speed dispersion and degassing, a conductive silver paste with a viscosity of 9850cps was obtained. The silver paste was transferred onto the diaphragm by screen printing or diluted inkjet printing (including aerosol jet printing). The diaphragm was then baked at 150℃ for 15 minutes, with a sample thickness of 50±2μm, and cut into sections. Spline, used to test the change in resistance of the diaphragm before and after stretching.

[0054] Comparative Example

[0055] Preparation process of conductive diaphragm: 15 parts of polyester elastomer were added to 40 parts of ethylene glycol butyl ether and stirred at high speed to dissolve. Then, 0.8 parts of leveling agent BYK-410, 0.5 parts of dispersant BYK-110, 0.5 parts of thixotropic agent BYK-607, 15 parts of nano silver powder (particle size D50 300nm), and 70 parts of flake silver powder (D50 3μm) were added sequentially and stirred thoroughly to form a mixed slurry. The mixed slurry was then stirred evenly using a dual planetary mixer. Finally, after high-speed dispersion and degassing, a conductive silver paste with a viscosity of 14060cps was obtained. The silver paste was transferred onto the diaphragm by screen printing or diluted inkjet printing (including aerosol jet printing). The diaphragm was then baked at 150℃ for 15 minutes, with a sample thickness of 50±2μm, and cut into sections. Spline, used to test the change in resistance of the diaphragm before and after stretching.

[0056] The performance test results of the conductive diaphragms in Examples 1 to 1 Comparative Examples are as follows:

[0057]

[0058] Performance test results show that controlling the particle size of the silver nanoparticles within a range (3-40 nm) can effectively reduce the rate of resistance change after stretching the resistance. In other words, the conductive diaphragm 100 proposed in this invention can control the rate of resistance change under stretching conditions, resulting in superior performance.

[0059] Example 3

[0060] This invention also provides a loudspeaker, which includes a conductive diaphragm as described in Embodiments 1 and 2 above, and the loudspeaker can achieve the technical effects described in Embodiments 1 and 2 above, which will not be repeated here.

[0061] The above description is merely an embodiment of the present invention. It should be noted that those skilled in the art can make improvements without departing from the inventive concept of the present invention, but these improvements all fall within the protection scope of the present invention.

Claims

1. A conductive diaphragm, characterized in that, The conductive diaphragm includes a main body layer and a conductive layer formed on the surface of the main body layer. The conductive layer includes an elastic matrix and conductive fillers dispersed within the elastic matrix. The components of the conductive layer, by mass ratio, include: 8-20 parts of the elastic matrix, 76-95 parts of the conductive fillers, and 0.1-3 parts of a modifier. The conductive fillers include nano-metal conductive fillers and micro-nano conductive fillers. The diameter of the nano-metal conductive fillers is 3-40 nm, and the diameter of the micro-nano conductive fillers is 0.2-9 μm. The weight ratio is 0.3:10-6:10; the melting point of the nano-metal conductive filler is below 200℃; the elastic matrix includes one or more of organosilicon elastomers, acrylate rubbers, ethylene acrylate rubbers, nitrile rubbers, hydrogenated nitrile rubbers, butyl rubbers, ethylene propylene rubbers, and thermoplastic elastomers; by using the nano-metal conductive filler as an auxiliary filler, the nano-metal conductive filler melts during the curing process, thereby allowing the conductive fillers in the elastic matrix to be fused together, in order to improve the conductivity of the conductive diaphragm and reduce the change in tensile resistance.

2. The conductive diaphragm as described in claim 1, characterized in that, The initial resistivity of the conductive layer is 1×10⁻⁶. -7 Ω·m⁻³×10 -6 The elastic modulus of the conductive layer is 5-400 MPa, and the elongation at break of the conductive layer is >100%. When the strain of the conductive diaphragm is ≤25%, the resistance change rate of the conductive diaphragm is ≤450%.

3. The conductive diaphragm as described in claim 1, characterized in that, The nano-metal conductive filler includes one or more of silver, gold, copper, aluminum, nickel, vanadium, indium, and palladium.

4. The conductive diaphragm as described in claim 1, characterized in that, The shape of the micro / nano conductive filler includes one or more of the following: spherical, near-spherical, sheet-like, dendritic, and rod-like.

5. The conductive diaphragm as described in claim 1, characterized in that, The micro / nano conductive filler includes one or more of the following: metallic materials, surface-plated metallic materials, and conductive carbon materials.

6. The conductive diaphragm according to claim 5, characterized in that, The metallic material includes one or more of silver, gold, copper, aluminum, nickel, vanadium, indium, and palladium.

7. The conductive diaphragm as described in claim 5, characterized in that, The surface metallization material includes one or more of silver-plated copper and silver-plated polymer particles.

8. The conductive diaphragm as described in claim 5, characterized in that, The conductive carbon material includes one or more of carbon black, graphene, and carbon nanotubes.

9. The conductive diaphragm as described in claim 1, characterized in that, The modifier includes one or more of the following: leveling agent, defoamer, conductivity promoter, thixotropic agent, and dispersant.

10. The conductive diaphragm as described in claim 1, characterized in that, The conductive layer is formed on one side of the surface of the main body layer or on both opposite sides of the main body layer and completely covers the surface of the main body layer; or the conductive layer is at least partially embedded in one side of the main body layer.

11. The conductive diaphragm as described in claim 10, characterized in that, The conductive layer is coated or adhered to the main body layer, or the conductive layer and the main body layer are integrally injection molded.

12. A loudspeaker, characterized in that, The loudspeaker includes a conductive diaphragm as described in any one of claims 1-11.

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