Waterproof breathable film, preparation method thereof and microphone

Abstract

The invention discloses a waterproof breathable film, a preparation method thereof and a microphone. A first protruding part and a second protruding part are formed on the waterproof breathable film, and the first protruding part protrudes towards the first side in the thickness direction of the waterproof breathable film and correspondingly forms a first concave area on the second side. The second protruding part protrudes towards the second side in the thickness direction of the waterproof breathable film and correspondingly forms a second concave area on the first side. The waterproof breathable film provided by the embodiment of the invention is of a three-dimensional structure comprising a first convex part, a second convex part, a corresponding first concave area and a corresponding second concave area; according to the structure, the mechanical performance and the acoustic performance can be improved at the same time, so that the durability is improved, and the negative influence on the acoustic performance of a microphone applying the structure is reduced.

Description

Technical Field

[0001] This application relates to the field of electronic product technology, and more specifically, to a waterproof and breathable membrane, a method for preparing the membrane, and a microphone. Background Technology

[0002] In the field of waterproofing, waterproof and breathable membranes are a key material, requiring both excellent waterproof and breathable properties to meet the needs of numerous applications, such as the protection of electronic devices (e.g., microphones). Electrospun membranes, as a promising waterproof and breathable membrane material, have received widespread attention in recent years.

[0003] Electrospun membranes are manufactured using an electrospinning process, resulting in fibers ranging from micrometers to nanometers in size. The membrane body is composed of a large number of these extremely fine fibers stacked together, with numerous pores between the fibers. This structural characteristic gives it the basic qualities to be a waterproof and breathable membrane. However, traditional electrospun membranes currently suffer from several significant drawbacks. Structurally, traditional electrospun membranes are typically planar; this simple planar structure results in a relatively limited surface area, which to some extent restricts performance improvement. When waterproof membranes are used in applications requiring high acoustic performance, such as microphones, the limited surface area leads to insufficient mechanical sensitivity. Specifically, when sound signals act on the waterproof membrane, the small surface area restricts the membrane's vibration amplitude, negatively impacting the microphone's acoustic performance. For example, it may degrade the transmission and reception of sound signals, reducing clarity and fidelity. In terms of mechanical properties, traditional planar electrospun membranes have poor mechanical strength and compressive strength. In actual use, the waterproof membrane may be subjected to various external forces, such as compression and friction. Due to insufficient mechanical strength and compressive strength, traditional electrospun membranes are prone to deformation and damage under these external forces, which affects the stability of their waterproof and breathable functions and reduces the product's service life and reliability.

[0004] In view of this, a new technical solution is needed to solve the above-mentioned technical problems. Summary of the Invention

[0005] One objective of this application is to provide a new technical solution for a waterproof and breathable membrane, its preparation method, and a microphone.

[0006] According to a first aspect of this application, a microphone is provided, wherein the waterproof and breathable membrane is formed of: The first protrusion protrudes towards the first side along the thickness direction of the waterproof and breathable membrane and forms a corresponding first recessed area on the second side. The second protrusion protrudes towards the second side along the thickness direction of the waterproof and breathable membrane and forms a corresponding second recessed area on the first side.

[0007] Optionally, the first protrusion and the second protrusion are connected to each other and arranged alternately.

[0008] Optionally, the cross-section of the first protrusion and / or the cross-section of the second protrusion are arc-shaped.

[0009] Optionally, the cross-section of the first protrusion and / or the cross-section of the second protrusion is triangular.

[0010] Optionally, the cross-section of the first protrusion and / or the cross-section of the second protrusion are trapezoidal.

[0011] Optionally, the waterproof and breathable membrane is made of one of polyimide, polyacrylonitrile, polyurethane, polyphenylene sulfide, or polyetheretherketone; and the thickness of the waterproof and breathable membrane is 3~20μm.

[0012] According to a second aspect of this application, a method for preparing a waterproof and breathable membrane as described in the first aspect is provided, the method comprising: The base film is manufactured using a roll forming process, and the base film has a first microstructure. An electrospun film is formed by depositing an electrospun film on the base film using an electrospun process. The base film and the electrospun film are calendered using a hot pressing process to construct the electrospun film into the waterproof and breathable film. The waterproof and breathable film has a second microstructure corresponding to the first microstructure. The second microstructure includes the first protrusion and the second protrusion.

[0013] Optionally, before depositing an electrospun film on the base film using the electrospinning process, the preparation method further includes: A release agent is sprayed onto the surface of the base film.

[0014] Optionally, the electrospinning process includes: The polymer is dissolved in a solvent to form a precursor spinning solution; Under the action of a high voltage electric field of 15-60kV, the precursor spinning solution is stretched to form nanofibers and deposited on the substrate to form the electrospun film. The electrospun film is dried to remove residual solvent.

[0015] According to a third aspect of this application, a microphone is provided, the microphone comprising a waterproof and breathable membrane as described in the first aspect.

[0016] The waterproof and breathable membrane provided in this application embodiment is a three-dimensional structure including a first protrusion and a second protrusion, as well as corresponding first and second recessed areas; this structure can simultaneously improve its mechanical and acoustic properties, thereby increasing its durability and reducing the negative impact on the acoustic performance of the microphones it is used with.

[0017] Other features and advantages of this application will become clear from the following detailed description of exemplary embodiments with reference to the accompanying drawings. Attached Figure Description

[0018] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments of the present application and, together with their description, serve to explain the principles of the present application.

[0019] Figure 1 This is a physical structural diagram of a waterproof and breathable membrane according to an embodiment of this application; Figure 2 This is a schematic diagram of the structure of a waterproof and breathable membrane according to an embodiment of this application. Figure 1 ; Figure 3 This is a schematic diagram of the structure of a waterproof and breathable membrane according to an embodiment of this application. Figure 2 ; Figure 4 This is a schematic diagram of the structure of a waterproof and breathable membrane according to an embodiment of this application. Figure 3 .

[0020] Explanation of reference numerals in the attached figures: 1. Waterproof and breathable membrane; 11. First protrusion; 12. First recessed area; 13. Second protrusion; 14. Second recessed area. Detailed Implementation

[0021] Various exemplary embodiments of the present application will now be described in detail with reference to the accompanying drawings. It should be noted that, unless otherwise specifically stated, the relative arrangement, numerical expressions, and values ​​of the components and steps set forth in these embodiments do not limit the scope of the present application.

[0022] The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the scope of this application and its application or use.

[0023] Techniques, methods, and equipment known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques, methods, and equipment should be considered part of the specification.

[0024] In all the examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may have different values.

[0025] It should be noted that similar labels and letters in the following figures indicate similar items; therefore, once an item is defined in one figure, it does not need to be discussed further in subsequent figures.

[0026] Reference Figures 1-4 As shown, according to one embodiment of this application, a waterproof and breathable membrane 1 is provided. The waterproof and breathable membrane 1 has a first protrusion 11 and a second protrusion 13. The first protrusion 11 protrudes toward a first side along the thickness direction of the waterproof and breathable membrane and forms a first recessed area 12 on a second side. The second protrusion 13 protrudes toward a second side along the thickness direction of the waterproof and breathable membrane and forms a second recessed area 14 on a first side.

[0027] In the waterproof and breathable membrane provided in the embodiments of this application, the membrane body is formed with a three-dimensional structure including a first protrusion 11 and a second protrusion 13 and corresponding first recessed region 12 and second recessed region 14; compared with the traditional planar membrane, the three-dimensional structure can increase the surface area of ​​the membrane and improve the mechanical properties of the membrane.

[0028] Specifically, the three-dimensional structure allows the membrane to have a larger actual surface area for the same projected area; furthermore, this concave-convex three-dimensional structure is similar to an arch structure in architecture, which can significantly improve the membrane's rigidity, compressive strength, and resistance to deformation. When the membrane is subjected to pressure from either side, the convex structure can effectively disperse and resist stress, preventing the membrane from being flattened or ruptured, thereby ensuring the long-term stability of the microphone ventilation channel in which it is applied.

[0029] In a microphone, the waterproof and breathable membrane serves as part of the acoustic diaphragm. When the membrane vibrates under the influence of sound waves, its stiffness and mass together determine its sensitivity. The raised structure makes the membrane more prone to macroscopic deformation; therefore, the waterproof and breathable membrane provided in this application embodiment can produce a larger vibration amplitude than a planar membrane under the same sound pressure, i.e., higher mechanical sensitivity. This means that it is more responsive to sound and introduces less acoustic loss, thereby minimizing the negative impact on the microphone's acoustic performance (such as sensitivity and frequency response curve) and optimizing acoustic performance for microphone applications.

[0030] In summary, the waterproof and breathable membrane provided in this application embodiment balances and simultaneously improves mechanical properties (compression resistance) and acoustic properties (sensitivity), thereby enhancing its durability and reducing its negative impact on the acoustic performance of the microphones it is used with.

[0031] Reference Figures 1-4 As shown, in one embodiment, the first protrusion 11 and the second protrusion 13 are connected to each other and arranged alternately.

[0032] In this specific example, a continuous, stable, and interlaced wave structure is formed throughout the waterproof and breathable membrane. This structure ensures that the membrane maintains its wave structure under tension. This arrangement makes the membrane structure more stable, better disperses stress, and ensures more uniform stress distribution when subjected to pressure or external forces. This effectively improves the overall mechanical strength and compressive strength of the membrane, enhancing its durability.

[0033] In other words, this continuous structure allows external pressure to be smoothly transmitted and dispersed along the entire membrane surface, avoiding stress concentration at any isolated point, and further enhancing the membrane's mechanical stability and fatigue resistance. Furthermore, the regular structure ensures that the membrane's mechanical and acoustic properties remain consistent throughout, improving product reliability and yield.

[0034] Reference Figure 2 As shown, in one embodiment, the cross-section of the first protrusion 11 and the cross-section of the second protrusion 13 are arc-shaped.

[0035] In this specific example, the arc-shaped structure can better disperse stress when subjected to external forces, reducing stress concentration and lowering the risk of membrane damage due to excessive local stress, thereby enhancing the membrane's mechanical strength and compressive strength. Simultaneously, the relatively smooth arc-shaped surface generates less resistance when in contact or rubbing against other components, which is beneficial for membrane installation and use. For example, the first protrusion 11 and the second protrusion 13 are alternately connected to form a continuous structure resembling a sine wave.

[0036] Optionally, the wavelength (λ) of the corrugated structure formed by the alternating connection of the first protrusion 11 and the second protrusion 13 is 5μm~200μm, the wave height (h) is 0.5~20μm, and the period ratio (h / λ) is 0.05~0.5.

[0037] Reference Figure 3 As shown, in one embodiment, the cross-section of the first protrusion 11 and / or the cross-section of the second protrusion 13 is triangular.

[0038] In this specific example, the triangular structure exhibits good stability, providing strong support for the membrane; its structural rigidity is the highest, effectively enhancing the membrane's mechanical strength and compressive strength; furthermore, the relatively regular shape of the triangle facilitates manufacturing and processing. For instance, the first protrusion 11 and the second protrusion 13 are alternately connected to form a continuous structure resembling a sawtooth wave.

[0039] Optionally, the wavelength (λ) of the corrugated structure formed by the alternating connection of the first protrusion 11 and the second protrusion 13 is 5μm~200μm, the wave height (h) is 0.5~20μm, and the bottom width is 2~100μm.

[0040] Reference Figure 4 As shown, in one embodiment, the cross-section of the first protrusion 11 and / or the cross-section of the second protrusion 13 is trapezoidal.

[0041] In this specific example, the trapezoidal structure combines some features of triangles and arcs, possessing a certain degree of stability and a large contact area; it has better resistance to flattening than an arc and less stress concentration than a triangle.

[0042] Optionally, the wavelength (λ) of the corrugated structure formed by the alternating connection of the first protrusion 11 and the second protrusion 13 is 5μm~200μm, the wave height (h) is 0.5~20μm, and the upper and lower bottom widths are 0.3~50μm.

[0043] Reference Figure 2 As shown, in one embodiment, the waterproof and breathable membrane is made of one of polyimide, polyacrylonitrile, polyurethane, polyphenylene sulfide, or polyetheretherketone; the thickness of the waterproof and breathable membrane is 3~20μm.

[0044] In this specific example, one of the following materials—polyimide, polyacrylonitrile, polyurethane, polyphenylene sulfide, or polyetheretherketone—is selected as the material for the waterproof and breathable membrane. These materials each possess excellent properties. For instance, polyimide exhibits excellent high-temperature resistance, mechanical properties, and chemical stability; polyurethane possesses good elasticity and abrasion resistance. These characteristics enable the waterproof and breathable membrane to adapt to different usage environments and requirements, thereby improving the overall performance of the membrane.

[0045] The thickness of the waterproof and breathable membrane is set at 3~20μm. Within this thickness range, the membrane can be guaranteed to have a certain strength and durability, without affecting the breathability and vibration amplitude due to excessive thickness. At the same time, it can also meet the requirements for product thinness and lightness, making it suitable for a variety of application scenarios.

[0046] Specifically, a waterproof and breathable membrane thickness of ≥3μm ensures the membrane possesses basic structural strength and integrity; if it is too thin, it is difficult to form a stable and reliable microstructure, resulting in insufficient mechanical strength. A waterproof and breathable membrane thickness of ≤20μm is crucial. For acoustic membranes, thickness is a key factor affecting sensitivity; a thinner membrane means higher acoustic sensitivity. Controlling the thickness limit to 20μm ensures that the membrane remains very lightweight overall, thereby maximizing its core objective of improving microphone acoustic performance.

[0047] According to another embodiment of this application, a method for preparing the waterproof and breathable membrane as described above is provided, the method comprising: S101. A bottom film is manufactured using a roll forming process, and the bottom film has a first microstructure. S102. An electrospun film is formed by depositing an electrospun film on the base film using an electrospun process. S103. The base film and the electrospun film are calendered using a hot pressing process to construct the electrospun film into the waterproof and breathable film. The waterproof and breathable film has a second microstructure corresponding to the first microstructure. The second microstructure includes the first protrusion and the second protrusion.

[0048] In the method for preparing the waterproof and breathable membrane provided in this application embodiment, in step S101, a bottom membrane is made by a roll pressing process; specifically, a bottom membrane with a first microstructure is made by a roll pressing process. The roll pressing process can precisely control the shape and size of the bottom membrane and can quickly and efficiently produce a large number of bottom membranes with consistency, providing a stable foundation for subsequent processes.

[0049] In step S102, an electrospun membrane is deposited using an electrospinning process. Specifically, an electrospinning membrane is deposited on a base film using an electrospinning process. The electrospinning membrane is composed of a large number of stacked nanofibers, and there are a large number of pores between the fibers, thus having good air permeability. By depositing on the base film, the electrospinning membrane and the base film can be better combined to form a composite membrane with a certain structure.

[0050] In step S103, a hot-pressing process is used to calender the base film and the electrospun film, constructing the electrospun film into a waterproof and breathable film with a second microstructure (including a first protrusion and a second protrusion) corresponding to the first microstructure. The hot-pressing process can better connect the two films together, enhance their bonding force, and at the same time form the required microstructure through calendering, further improving the surface area, mechanical strength and pressure resistance of the waterproof and breathable film.

[0051] In one embodiment, before depositing an electrospun film on the base film using an electrospinning process, the preparation method further includes spraying a release agent onto the surface of the base film.

[0052] In this specific example, the release agent can prevent excessive adhesion between the electrospun membrane and the base film in subsequent processes, allowing for easier, more complete, and undamaged separation of the finished waterproof and breathable membrane from the base film after preparation. This improves production efficiency and product quality, and reduces damage or surface defects to the waterproof and breathable membrane caused by adhesion. Optionally, the release agent is a silicone oil release agent.

[0053] In one embodiment, the electrospinning process includes: S1021. Dissolve the polymer in a solvent to form a precursor spinning solution; S1022. Under the action of a high voltage electric field of 15-60kV, the precursor spinning solution is stretched to form nanofibers and deposited on the base film to form the electrospun film. S1023. The electrospun film is dried to remove residual solvent.

[0054] In this specific example, in step S1021, the polymer is dissolved in a solvent to form a precursor spinning solution. This is a fundamental step in the electrospinning process. By selecting suitable polymers and solvents, the properties of the solution, such as viscosity and conductivity, can be controlled, thereby adjusting the subsequent spinning process and the properties of the formed nanofibers. Optionally, the polymer can be polyimide, polyacrylonitrile, polyurethane, polyphenylene sulfide, or polyetheretherketone; the solvent can be, for example, DMF, NMP, etc.

[0055] In step S1022, under the action of a high voltage electric field of 15-60kV, the precursor spinning solution is stretched to form nanofibers and deposited on the bottom film to form an electrospun membrane. The high voltage electric field can charge the spinning solution. Under the action of the electric field force, the solution is stretched into extremely fine nanofibers. These nanofibers are stacked on the bottom film to form a membrane structure with a large number of pores. This structure gives the membrane good air permeability.

[0056] In step S1023, the electrospun membrane is dried to remove residual solvent. Residual solvent may affect the performance and stability of the membrane, such as causing the membrane to soften, deform, or affect its waterproof performance. Drying can ensure the stability of the membrane's performance and improve its quality and reliability.

[0057] In one embodiment, the concentration of the precursor spinning solution is 8-12 wt%.

[0058] In this specific example, the concentration of the precursor spinning solution is set to 8-12 wt%. Within this concentration range, the spinning solution has suitable viscosity and conductivity, ensuring smooth stretching to form uniform nanofibers under a high-voltage electric field. If the concentration is too low, the solution viscosity is too small, making it difficult to form stable fibers; if the concentration is too high, the solution viscosity is too large, making it prone to breakage during stretching, thus affecting fiber quality and membrane performance.

[0059] In one embodiment, the spinneret distance for stretching the precursor spinning solution to form nanofibers is 10-20 cm, and the flow rate is 0.1-0.5 ml / h.

[0060] In this specific example, the spinneret distance for stretching the precursor spinning solution to form nanofibers is set to 10-20 cm. A suitable spinneret distance ensures that the nanofibers have sufficient time to be stretched and solidified during flight, forming uniform, slender fibers. If the distance is too short, the fibers may not have enough time to be fully stretched before depositing on the substrate, resulting in coarser fibers. If the distance is too long, the fibers may be affected by external factors during flight, leading to breakage or uneven distribution. The flow rate is set to 0.1-0.5 ml / h. A suitable flow rate controls the supply of the spinning solution, matching the effect of the high-voltage electric field to ensure continuous fiber formation. If the flow rate is too fast, too much solution will be supplied, potentially leading to overly thick fibers or dripping. If the flow rate is too slow, insufficient solution supply may result in fiber breakage, affecting membrane formation and quality.

[0061] In one embodiment, the base film is a cast film made of PET or PI; the roller surface used in the rolling process has a template microstructure, which corresponds to the first microstructure.

[0062] In this specific example, the base film is a cast film made of PET or PI. PET and PI materials have good mechanical properties, chemical stability and thermal stability, which can provide a stable support foundation for electrospun film. Furthermore, they can maintain good shape and performance during subsequent hot pressing and other processes, and are not easily deformed or damaged, which helps to ensure the quality of the final waterproof and breathable membrane.

[0063] The rollers used in the roll forming process have template microstructures on their surfaces, which correspond to the first microstructure. Through the rolling action of the rollers, the template microstructures can be accurately copied onto the base film to form a first microstructure with a specific shape and size. This lays the foundation for the subsequent formation of a waterproof and breathable membrane with a second microstructure, ensuring the structural accuracy and consistency of the membrane.

[0064] In one embodiment, the hot pressing roller used in the hot pressing process is made of silicone rubber, the calendering temperature is 80~300℃, and the calendering pressure is 0.5~10Mpa.

[0065] In this specific example, the hot press roller used in the hot pressing process is made of silicone rubber. Silicone rubber has good elasticity and flexibility, and can make full contact with the film surface during the hot pressing process, so that the pressure is evenly distributed and the film structure is not damaged due to excessive local pressure. At the same time, silicone rubber has a certain high temperature resistance and can adapt to the temperature requirements of the hot pressing process.

[0066] The calendering temperature is set between 80 and 300°C. Within this temperature range, the base film and the electrospun film can fuse together better, while promoting the formation and stabilization of the internal structure of the film. The calendering pressure is set between 0.5 and 10 MPa. Appropriate pressure ensures the bonding force between the two films, allowing them to adhere tightly and form a waterproof and breathable membrane with good performance. If the pressure is too low, the bonding will not be tight, and the required second microstructure cannot be formed; if the pressure is too high, it may damage the membrane structure or cause unnecessary deformation of the membrane.

[0067] According to yet another embodiment of this application, a microphone is provided, the microphone including the waterproof and breathable membrane 1 as described above.

[0068] The microphone provided in this application embodiment includes the aforementioned waterproof and breathable membrane. Because this membrane has a large surface area, good mechanical strength, and compressive strength, when applied to a microphone, the large surface area increases the membrane's mechanical sensitivity, effectively enhancing its vibration amplitude. During microphone operation, sound signals cause the membrane to vibrate; increased vibration amplitude allows for more accurate sound signal capture, reducing the impact on the microphone's acoustic performance and improving its sound quality and performance stability.

[0069] The above embodiments mainly describe the differences between the various embodiments. As long as the different optimization features between the various embodiments are not contradictory, they can be combined to form a better embodiment. For the sake of brevity, they will not be elaborated here.

[0070] While specific embodiments of this application have been described in detail by way of examples, those skilled in the art should understand that the above examples are for illustrative purposes only and are not intended to limit the scope of this application. Those skilled in the art should understand that modifications can be made to the above embodiments without departing from the scope and spirit of this application. The scope of this application is defined by the appended claims.

Claims

1. A waterproof and breathable membrane, characterized in that, The waterproof and breathable membrane is formed of: The first protrusion (11) is provided to protrude toward the first side along the thickness direction of the waterproof and breathable membrane and a first recessed area (12) is formed on the second side. The second protrusion (13) is provided to protrude toward the second side along the thickness direction of the waterproof and breathable membrane and forms a second recessed area (14) on the first side.

2. The waterproof and breathable membrane according to claim 1, characterized in that, The first protrusion (11) and the second protrusion (13) are connected to each other and arranged alternately.

3. The waterproof and breathable membrane according to claim 1 or 2, characterized in that, The cross-section of the first protrusion (11) and / or the cross-section of the second protrusion (13) are arc-shaped.

4. The waterproof and breathable membrane according to claim 1 or 2, characterized in that, The cross-section of the first protrusion (11) and / or the cross-section of the second protrusion (13) is triangular.

5. The waterproof and breathable membrane according to claim 1 or 2, characterized in that, The cross-section of the first protrusion (11) and / or the cross-section of the second protrusion (13) are trapezoidal.

6. The waterproof and breathable membrane according to claim 1 or 2, characterized in that, The waterproof and breathable membrane is made of one of the following materials: polyimide, polyacrylonitrile, polyurethane, polyphenylene sulfide, or polyetheretherketone; the thickness of the waterproof and breathable membrane is 3~20μm.

7. A method for preparing a waterproof and breathable membrane as described in any one of claims 1-6, characterized in that, The preparation method includes: The base film is manufactured using a roll forming process, and the base film has a first microstructure. An electrospun film is formed by depositing an electrospun film on the base film using an electrospun process. The base film and the electrospun film are calendered using a hot pressing process to construct the electrospun film into the waterproof and breathable film. The waterproof and breathable film has a second microstructure corresponding to the first microstructure. The second microstructure includes the first protrusion and the second protrusion.

8. The preparation method according to claim 7, characterized in that, Before depositing an electrospun film on the substrate using an electrospinning process to form an electrospun film, the preparation method further includes: A release agent is sprayed onto the surface of the base film.

9. The preparation method according to claim 7, characterized in that, The electrospinning process includes: The polymer is dissolved in a solvent to form a precursor spinning solution; Under the action of a high voltage electric field of 15-60kV, the precursor spinning solution is stretched to form nanofibers and deposited on the substrate to form the electrospun film. The electrospun film is dried to remove residual solvent.

10. A microphone, characterized in that, The microphone includes a waterproof and breathable membrane (1) as described in any one of claims 1-6.

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