An ultrathin composite acoustic membrane and automotive component

Abstract

This invention relates to the field of automotive acoustic materials and functional thin films, specifically to a composite acoustic membrane with ultra-thin thickness and high sound insulation performance, and its application in automotive components. It comprises at least two sound wave reflecting layers and at least two damping layers stacked together, with the at least two sound wave reflecting layers and at least two damping layers alternately arranged within the membrane; the total thickness of the ultra-thin composite acoustic membrane is less than or equal to 100 μm. This invention achieves a breakthrough unity of ultra-thinness and high sound insulation: It creatively employs a synergistic acoustic architecture of "at least two sound wave reflecting layers and at least two damping layers alternately arranged," successfully achieving a weighted sound insulation (Rw) of up to 18-28 dB(A) across the entire frequency band at an ultra-thin scale with a total thickness ≤100 μm (preferably 38-50 μm).

Description

Technical Field

[0001] This invention relates to the field of automotive acoustic materials and functional films, specifically to a composite acoustic film with ultra-thin thickness and high sound insulation performance, and its application in automotive components. Background Technology

[0002] With the automotive industry's pursuit of lightweighting, electrification, and a premium driving experience, cabin noise and vibration (NVH) have become one of the core competitive indicators. To improve NVH performance, effective sound insulation materials need to be applied to areas such as doors, pillars, dashboards, and windows. However, the interior space of a car, especially the gaps between interior panels and glass, is extremely limited, posing a significant challenge to traditional sound insulation solutions.

[0003] Currently, automotive sound insulation and noise reduction mainly employ the following technologies: 1. Thick, composite sound insulation / damping materials: such as asphalt damping sheets, butyl rubber, heavy foam, etc., typically with a thickness ranging from several millimeters to centimeters. While these materials offer some sound insulation or vibration reduction, their weight and space requirements severely restrict automotive lightweighting, and their improvement in low-frequency sound insulation is limited. For example, patent document CN223763966U discloses a metal-damping composite layer for suppressing engine vibration, with an overall thickness in the millimeter range (<12mm), making it unsuitable for use in the confined space of a vehicle interior.

[0004] 2. Structural sound-absorbing membranes: such as patent document CN215906129U, which absorb sound waves by designing sound-absorbing triangular strips, sound-absorbing holes, and filling with glass wool within the membrane. This type of solution results in a relatively thick membrane (usually several hundred micrometers or more), and the sound insulation performance depends on the complex three-dimensional structure, making it difficult to achieve efficient sound insulation in an ultra-thin state.

[0005] 3. Multifunctional car wrap film: As shown in patent document CN113429901A, porous inorganic nanoparticles are doped into a TPU substrate to achieve sound absorption, and a nanoscale metal layer is provided for optical heat insulation. Its noise reduction mechanism relies on the sound wave friction loss of porous materials. The total thickness of the film layer is usually over 200μm, and it is not specifically designed for sound wave reflection, resulting in limited sound insulation performance across the entire frequency range, especially in low-frequency sound insulation.

[0006] 4. Simple multilayer thin films: Some existing technologies use a single-layer metal reflective layer combined with a polymer substrate in an attempt to achieve sound insulation. However, such structures have low sound insulation in ultra-thin states (e.g., <100μm), and the single metal layer is prone to oxidation, causing the acoustic performance to degrade over time.

[0007] As mentioned above, existing technologies generally suffer from the contradiction of being unable to simultaneously achieve "high sound insulation performance," "ultra-thin thickness / lightweight," and "long-term durability." Specifically, how to achieve efficient and stable isolation of noise across the entire 20Hz-20kHz frequency band at an ultra-thin scale of less than or equal to 100μm, especially 38-50μm, remains a long-standing technical challenge in this field. Summary of the Invention

[0008] The present invention aims to overcome the shortcomings of the prior art and solves the technical problem of providing an ultra-thin composite acoustic membrane that can achieve efficient sound insulation of all frequency band noises such as wind noise, road noise, and engine noise through an innovative layer structure design, under the constraint of a total thickness of less than or equal to 100μm. At the same time, it has excellent durability, lightweight characteristics and ease of construction, and is particularly suitable for sound insulation and noise reduction in parts of automobiles where space and weight are strictly limited.

[0009] To solve the above-mentioned technical problems, the present invention adopts the following technical solution: According to one aspect of the present invention, an ultrathin composite acoustic membrane is provided, comprising at least two acoustic wave reflecting layers and at least two damping layers stacked thereon, wherein the at least two acoustic wave reflecting layers and the at least two damping layers are alternately arranged in the membrane; the total thickness of the ultrathin composite acoustic membrane is less than or equal to 100 μm.

[0010] In a preferred embodiment of the present invention, the ultrathin composite acoustic membrane comprises two acoustic wave reflecting layers and two damping layers.

[0011] Furthermore, the two acoustic wave reflecting layers and the two damping layers are arranged alternately, and an isolation layer is provided between the two acoustic wave reflecting layers. The membrane is a 10-layer composite structure comprising a surface protective layer, a bonding layer, an acoustic wave reflecting layer, a damping layer, an isolation layer, an acoustic wave reflecting layer, a damping layer, a sealing layer, an adhesive layer, and a protective layer.

[0012] Furthermore, the two acoustic wave reflecting layers include a first reflecting layer and a second reflecting layer, wherein the first reflecting layer is configured to primarily reflect low-frequency acoustic waves (e.g., 20Hz-300Hz), and the second reflecting layer is configured to primarily reflect mid-to-high frequency acoustic waves (e.g., 300Hz-20kHz).

[0013] Further, the first reflective layer comprises silver or a silver alloy, and the second reflective layer comprises chromium nitride ceramic. In a more preferred embodiment, the first reflective layer is a silver-titanium alloy layer, and the second reflective layer is a chromium nitride ceramic layer.

[0014] Furthermore, the damping layer is a polyurethane damping layer.

[0015] Furthermore, the total thickness of the ultrathin composite acoustic diaphragm is 38 μm to 50 μm. In one specific embodiment, the total thickness is 38 μm, and its weighted noise isolation for the 20 Hz-20 kHz frequency band is not less than 18 dB(A). In another specific embodiment, the total thickness is 50 μm, and its weighted noise isolation for the 20 Hz-20 kHz frequency band is not less than 25 dB(A).

[0016] Furthermore, the ultrathin composite acoustic membrane also includes a pressure-sensitive damping adhesive layer disposed on the innermost side of the membrane.

[0017] According to another aspect of the present invention, a method for preparing the above-mentioned ultrathin composite acoustic membrane is provided, comprising forming the acoustic wave reflecting layer by physical vapor deposition process, and integrating the damping layer and the adhesive layer by wet composite process.

[0018] According to another aspect of the present invention, an automotive component is provided, the surface of which is attached with the ultrathin composite acoustic film described in any of the above claims, the automotive component being automotive glass, door interior panel, dashboard or pillar trim panel.

[0019] The beneficial effects of this invention are: 1) Achieving a breakthrough in the unity of ultra-thinness and high sound insulation: This invention creatively adopts a synergistic acoustic architecture of "alternating arrangement of at least two sound wave reflecting layers and at least two damping layers," successfully achieving high-efficiency full-frequency sound insulation with a weighted sound insulation (Rw) of 18-28 dB(A) within an ultra-thin dimension with a total thickness ≤100μm (preferably 38-50μm). This effectively solves the technical contradiction in traditional solutions that "sound insulation requires increased thickness and weight," providing key materials for the simultaneous improvement of automotive lightweighting and high-end NVH performance.

[0020] 2) Excellent sound insulation across the entire frequency range, especially at low frequencies: By setting up a first reflective layer (primarily reflecting low frequencies) and a second reflective layer (primarily reflecting mid-to-high frequencies) with clearly defined functions, and in conjunction with the corresponding damping layer, a multi-stage acoustic attenuation path of "reflection-dissipation-re-reflection-re-dissipation" is constructed. This path is particularly effective for low-frequency noise that is difficult to isolate (such as road noise and engine idling noise), overcoming the shortcomings of conventional thin-film sound insulation in low frequencies.

[0021] 3) Compact structure and excellent durability: A 10-layer composite structure is preferred, with an isolation layer to prevent interference between reflective layers and a sealing layer to protect the core functional layer. The reflective layer uses a combination of silver-titanium alloy (anti-oxidation) and chromium nitride ceramic (high stability, non-oxidizing), ensuring the long-term acoustic performance stability of the membrane system in the harsh automotive environment (-40℃~120℃) from the material source, with a lifespan matching that of the entire vehicle. 4) Extreme space and weight advantages: The total thickness of the film is only 38-50μm, and it is extremely lightweight. After application, it takes up virtually no usable space and does not affect the original interior design, assembly and function. It achieves extremely low space occupation and does not affect the original interior design and function. It is especially suitable for space-constrained areas such as door panels, pillars and the back of the dashboard.

[0022] 5) Convenient construction and flexible application: The innermost layer of the membrane system has a built-in pressure-sensitive damping adhesive layer, which can be directly pasted by simply peeling off the release film. Construction is simple and quick, and the adhesive layer itself can also supplement the damping effect. The membrane has good flexibility and can be applied to various complex curved surfaces. 6) Mature technology, conducive to industrialization: The preparation method combines physical vapor deposition (such as magnetron sputtering) and precision wet composite process, which is suitable for large-scale, high-efficiency roll-to-roll continuous production, with controllable cost and good quality consistency. Attached Figure Description

[0023] Figure 1 This is a schematic cross-sectional view of the 10-layer structure of an ultrathin composite acoustic membrane according to a preferred embodiment of the present invention.

[0024] Figure 2 This is a schematic diagram illustrating the application of the ultra-thin composite acoustic film of this invention to automotive side window glass.

[0025] Figure reference numerals: 1-Surface PET protective layer; 2-First transition bonding layer; 3-Ag-Ti alloy first reflective layer; 4-First PU damping layer; 5-Intermediate isolation support layer (isolation layer); 6-CrN x 7-Ceramic second reflective layer; 8-Second PU damping layer; 9-Interlayer sealing layer; 10-Damping adhesive underlayer (pressure-sensitive damping adhesive layer); 11-Release protective layer; 12-Ultra-thin composite acoustic membrane; 23-Automotive glass; 34-Window frame. Detailed Implementation The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application. In addition, it should be understood that the specific embodiments described herein are only for illustration and explanation of this application and are not intended to limit this application. In this application, unless otherwise stated, directional terms such as "upper," "lower," "inner," and "outer" generally refer to the orientation of the device in its actual use or working state, specifically the direction shown in the drawings.

[0026] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined with "first" or "second" may explicitly or implicitly include at least one of that feature.

[0027] This application provides an ultrathin composite acoustic diaphragm and an automotive component, which are described in detail below. It should be noted that the order of description of the following embodiments is not intended to limit the preferred order of the embodiments of this application. Furthermore, the descriptions of each embodiment have their own emphasis; parts not described in detail in a certain embodiment can be referred to in the relevant descriptions of other embodiments.

[0028] Please see Figure 1 The embodiments of this application provide an ultrathin composite acoustic membrane 100, which includes at least two acoustic wave reflecting layers and at least two damping layers stacked together.

[0029] In this membrane, the at least two acoustic wave reflecting layers and the at least two damping layers are arranged alternately. This alternating arrangement structure forms a multi-stage synergistic acoustic attenuation path of "reflection-dissipation-re-reflection-re-dissipation," thereby significantly improving sound insulation efficiency, especially the ability to isolate low-frequency noise.

[0030] The total thickness of the ultrathin composite acoustic diaphragm 100 is less than or equal to 100 μm. Preferably, the total thickness is 38 μm to 50 μm. This ultrathin characteristic allows the diaphragm system to occupy virtually no installation space, achieving extreme lightweighting.

[0031] In some embodiments, the ultrathin composite acoustic membrane 100 includes two acoustic wave reflecting layers and two damping layers. The two acoustic wave reflecting layers and the two damping layers are arranged alternately.

[0032] Furthermore, an isolation layer 5 is provided between the two acoustic wave reflecting layers. The isolation layer 5 can be used to physically separate the two reflecting layers, avoid acoustic interference or resonance between the layers, and ensure that they work independently and collaboratively.

[0033] In a specific preferred embodiment, the ultrathin composite acoustic diaphragm 100 has a 10-layer composite structure. Please refer to [link / reference]. Figure 1 The 10-layer structure, from the outside in (with the side furthest from the automotive component during attachment as "outer"), includes: a surface PET protective layer 1, a first transition bonding layer 2, a first reflective layer 3, a first damping layer 4, an isolation layer 5, a second reflective layer 6, a second damping layer 7, an interlayer sealing layer 8, a damping adhesive underlayer 9, and a release protective layer 10. It is understood that in other embodiments, certain auxiliary layers may be omitted or added, or the order of the layers may be adjusted, as long as they contain alternating double reflective and double damping layers, all of which fall within the scope of protection of this application.

[0034] The surface PET protective layer 1 can be made of biaxially oriented modified polyethylene terephthalate (PET) film with a thickness of, for example, 5 μm to 6 μm. The surface PET protective layer 1 provides mechanical support, scratch resistance and UV resistance, and serves as the first contact interface for sound waves.

[0035] The first transition bonding layer 2 is disposed inside the surface PET protective layer 1, and its material is, for example, an ultra-thin polyurethane adhesive with a thickness of approximately 2 μm. The first transition bonding layer 2 is used to enhance the adhesion between the PET protective layer and the subsequent metal plating layer and prevent interlayer peeling.

[0036] A first reflective layer 3 is disposed inside the first transition bonding layer 2. The first reflective layer 3 is configured to primarily reflect low-frequency sound waves (e.g., 20Hz-300Hz). Exemplarily, the first reflective layer 3 comprises silver or a silver alloy. More preferably, the first reflective layer 3 is a silver-titanium (Ag-Ti) alloy layer, formed by a physical vapor deposition (PVD) process such as magnetron sputtering, with a thickness of, for example, 3μm to 4μm. The incorporation of titanium significantly improves the oxidation resistance of the silver layer.

[0037] The first damping layer 4 is disposed inside the first reflective layer 3. The first damping layer 4 is used to dissipate the acoustic energy penetrating the first reflective layer 3 and convert it into heat energy. For example, the first damping layer 4 is a polyurethane (PU) damping layer, made of a flexible polyurethane material with a high loss factor, and has a thickness of, for example, 4 μm to 5 μm.

[0038] The isolation layer 5 is disposed inside the first damping layer 4. The isolation layer 5 is, for example, an ultra-thin PET film with a thickness of about 2 μm, and its core function is to physically isolate the two acoustic wave reflecting layers.

[0039] A second reflective layer 6 is disposed inside the insulating layer 5. The second reflective layer 6 is configured to primarily reflect mid-to-high frequency sound waves (e.g., 300Hz-20kHz). Exemplarily, the second reflective layer 6 comprises chromium nitride ceramic. More preferably, the second reflective layer 6 is chromium nitride (CrN). x The ceramic layer, formed through processes such as reactive magnetron sputtering, has a thickness of, for example, 3 μm to 4 μm. CrN x The ceramic layer has the characteristics of high hardness, corrosion resistance, and never oxidizing.

[0040] The second damping layer 7 is disposed inside the second reflective layer 6. The second damping layer 7 is used to further dissipate residual acoustic energy. Exemplarily, the second damping layer 7 is a polyurethane (PU) damping layer with a thickness of, for example, 5 μm to 7 μm.

[0041] An interlayer sealing layer 8 is disposed inside the second damping layer 7. The interlayer sealing layer 8 is, for example, an acrylic sealant with a thickness of approximately 2 μm, used to encapsulate the interior of the membrane system, block moisture and oxygen, and provide long-term protection for the metal reflective layer.

[0042] The damping adhesive underlayer 9 is disposed inside the interlayer sealing layer 8. The damping adhesive underlayer 9 is a pressure-sensitive damping adhesive layer, which is made of automotive-grade pressure-sensitive adhesive and contains damping fillers in the adhesive formulation. This layer has a thickness of, for example, 7μm to 10μm, and serves both to provide adhesive strength and to supplement damping and noise reduction.

[0043] The release protective layer 10 is located on the outside of the damping adhesive base layer 9 (i.e. the side facing the installer when applying), and is a silicone oil release film with a thickness of about 3μm, which is peeled off during use.

[0044] The aforementioned 10-layer structure can be fabricated using a continuous integrated process of "vacuum magnetron sputtering (for forming the reflective layer) + precision coating and lamination (for forming the remaining layers)".

[0045] Through the combination of the aforementioned specific materials and structures, the ultrathin composite acoustic membrane of this application achieves excellent sound insulation performance and durability at an extremely thin thickness. The two reflective layers work together for different frequency bands, and the two damping layers are matched with them for graded dissipation. Combined with the selection of antioxidant and highly stable materials, the technical problem of simultaneously achieving ultrathinness, high sound insulation, and long lifespan is solved.

[0046] In some embodiments, the total thickness of the ultrathin composite acoustic diaphragm 100 is 38 μm. At this thickness, its weighted noise isolation for the 20 Hz-20 kHz frequency band is not less than 18 dB(A). In other embodiments, the total thickness is 50 μm, and its weighted noise isolation for the 20 Hz-20 kHz frequency band is not less than 25 dB(A).

[0047] Accordingly, embodiments of this application also provide an automotive component, the surface of which is attached with the ultrathin composite acoustic membrane 100 provided in any of the foregoing embodiments.

[0048] In some embodiments, automotive components are automotive glass, door trim panels, dashboards, or pillar trim panels. Because the ultra-thin composite acoustic diaphragm 100 has an extremely small total thickness (38-50 μm) and is flexible, it can perfectly conform to the complex curved surfaces of these components, significantly improving the sound insulation performance of these areas without occupying much space or affecting the original design and function, thereby optimizing the overall vehicle cabin quietness (NVH).

[0049] Example 1 Please see Figure 1In this embodiment, an ultrathin composite acoustic diaphragm 100 is provided, which has a 10-layer structure with a total thickness of 38 μm. The materials and thicknesses of each layer are as described above (surface PET protective layer 1: 5 μm; first transition bonding layer 2: 2 μm; Ag-Ti alloy first reflective layer 3: 3 μm; first PU damping layer 4: 4 μm; isolation layer 5: 2 μm; CrN...). x Ceramic second reflective layer 6: 3μm; second PU damping layer 7: 5μm; interlayer sealing layer 8: 2μm; pressure-sensitive damping adhesive layer 9: 7μm; release protective layer 10: 3μm).

[0050] Performance testing: The airborne weighted sound insulation (Rw) was tested according to ISO 717-1 standard. The result was 21 dB(A), meeting the requirement of not less than 18 dB(A). After 1000 hours of damp heat aging test at 85℃ / 85%RH, the sound insulation attenuation was less than 0.5 dB(A).

[0051] Example 2 In this embodiment, an ultrathin composite acoustic diaphragm 100 is provided, which has the same structure as in Embodiment 1. Performance is improved by thickening key functional layers: the Ag-Ti alloy first reflective layer 3 has a thickness of 4 μm, the first PU damping layer 4 has a thickness of 5 μm, and CrN... x The ceramic second reflective layer 6 has a thickness of 4 μm, the second PU damping layer 7 has a thickness of 7 μm, and the pressure-sensitive damping adhesive layer 9 has a thickness of 10 μm. The total thickness is 50 μm.

[0052] Performance testing: Under the same conditions, its weighted isolation (Rw) reached 27 dB(A), which meets the requirement of not less than 25 dB(A).

[0053] Comparative Example To highlight the effects of the present invention, the following comparative examples are provided: Comparative Example 1: A 2.0 mm thick commercial butyl rubber asphalt damping plate was selected, with a weighted sound insulation of approximately 22 dB(A).

[0054] Comparative Example 2: A TPU film containing porous SiO2 filler was prepared according to the prior art, with a thickness of about 220 μm and a weighted sound insulation of about 13 dB(A).

[0055] Comparative Example 3: A four-layer single reflective film with a structure of PET (5μm) / Ag (3μm) / PU (30μm) / adhesive layer (10μm) was prepared with a total thickness of 48μm. Its weighted sound insulation was about 15 dB(A), and the sound insulation decreased significantly after 100 hours of damp heat aging.

[0056] The sound insulation performance of Examples 1 and 2 of the present invention is far superior to that of Comparative Examples 2 and 3 at an ultra-thin thickness, and when the performance is close to that of Comparative Example 1, the thickness is only about 1 / 40 to 1 / 50 of the latter.

[0057] Application Examples Please see Figure 2 The ultrathin composite acoustic membrane 100 prepared in Example 1 was peeled off, and then directly attached to the inner surface of the automotive side window glass 200 through its pressure-sensitive damping adhesive layer 9. After bonding, the membrane system increased in thickness by only 38μm, which has almost no impact on window operation, visibility, or appearance, but can significantly block external wind noise and road noise from entering the cabin.

[0058] It is understood that the terms used in the embodiments of this application have the same meaning. For any content not described in detail in a certain embodiment, the specific implementation details can be referred to the descriptions in other embodiments. The examples and technical effects shown in the foregoing embodiments can be implemented accordingly. Unless explicitly excluded or there are principle obstacles that prevent the various embodiments from being combined, the various embodiments can be used in combination with each other. For the repeated parts, this specification will not elaborate further.

[0059] The above provides a detailed description of the ultrathin composite acoustic diaphragm and automotive components provided in this application. Specific examples have been used to illustrate the principles and implementation methods of this application. The descriptions of the above embodiments are only for the purpose of helping to understand the methods and core ideas of this application. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of this application. Therefore, the content of this specification should not be construed as a limitation of this application.

Claims

1. An ultrathin composite acoustic diaphragm, characterized in that, The membrane comprises at least two acoustic wave reflecting layers and at least two damping layers stacked together, wherein the at least two acoustic wave reflecting layers and the at least two damping layers are alternately arranged in the membrane; the total thickness of the ultrathin composite acoustic membrane is less than or equal to 100 μm.

2. The ultrathin composite acoustic diaphragm according to claim 1, characterized in that, It includes two acoustic wave reflecting layers and two damping layers.

3. The ultrathin composite acoustic diaphragm according to claim 2, characterized in that, The two acoustic wave reflecting layers and the two damping layers are arranged alternately, and an isolation layer is provided between the two acoustic wave reflecting layers. The membrane is a 10-layer composite structure comprising a surface protective layer, a bonding layer, an acoustic wave reflecting layer, a damping layer, an isolation layer, an acoustic wave reflecting layer, a damping layer, a sealing layer, an adhesive layer, and a protective layer.

4. The ultrathin composite acoustic membrane according to claim 2 or 3, characterized in that, The two acoustic wave reflecting layers include a first reflecting layer and a second reflecting layer. The first reflecting layer is configured to primarily reflect low-frequency acoustic waves, and the second reflecting layer is configured to primarily reflect mid- to high-frequency acoustic waves.

5. The ultrathin composite acoustic diaphragm according to claim 4, characterized in that, The first reflective layer comprises silver or a silver alloy, and the second reflective layer comprises chromium nitride ceramic.

6. The ultrathin composite acoustic diaphragm according to claim 5, characterized in that, The first reflective layer is a silver-titanium alloy layer, and the second reflective layer is a chromium nitride ceramic layer.

7. The ultrathin composite acoustic membrane according to any one of claims 1-3, characterized in that, The damping layer is a polyurethane damping layer.

8. The ultrathin composite acoustic diaphragm according to claim 1, characterized in that, The total thickness is 38 μm to 50 μm.

9. The ultrathin composite acoustic diaphragm according to claim 8, characterized in that, The total thickness is 38μm, and its weighted isolation for noise in the 20Hz-20kHz frequency band is not less than 18dB(A).

10. The ultrathin composite acoustic diaphragm according to claim 8, characterized in that, The total thickness is 50μm, and its weighted isolation for noise in the 20Hz-20kHz frequency band is not less than 25dB(A).

11. The ultrathin composite acoustic membrane according to claim 10, characterized in that, It also includes a pressure-sensitive damping adhesive layer disposed on the innermost side of the membrane.

12. An automotive component, characterized in that, Its surface is covered with an ultra-thin composite acoustic membrane as described in any one of claims 1-11, and the automotive component is automotive glass, door interior panel, dashboard or pillar trim panel.

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