Noise reduction skin material and preparation method thereof

Abstract

The invention relates to the technical field of polymer composite material synthesis, and discloses a noise-reduction skin material and a preparation method thereof.According to the noise-reduction skin material and the preparation method thereof, the multi-layer structure design of a surface layer, a sound absorption layer and a sound insulation layer is adopted, and the surface layer is subjected to electrolytic oxidation treatment to generate a porous oxidation film, so that sound wave scattering and interface impedance matching are enhanced; the gradient pores are formed in the sound absorption layer, so that wide-frequency-band noise can be effectively absorbed, and the noise reduction efficiency is improved; the sound insulation layer is formed by compounding nanoscale silicon dioxide aerogel and graphene and has the characteristics of high acoustic impedance and low density, the isolation effect of the material on high-frequency noise is further enhanced, and the noise attenuation rate of the material within the frequency range of 50-5000 Hz reaches 30 dB or above.

Description

Technical Field

[0001] This invention belongs to the field of polymer composite material synthesis technology, and particularly relates to a noise reduction skin material and its preparation method. Background Technology

[0002] Skin materials refer to composite materials used to cover or wrap the surface of a structure. They are usually composed of multiple functional components and are widely used in the automotive, aerospace, rail transportation and construction fields. As an outer protective material, they bear a certain mechanical strength and impact resistance, and block the external environment (such as temperature, humidity and chemical substances) from corroding the internal structure. At the same time, they meet specific needs through the physical or chemical properties of the material itself (such as noise reduction, heat insulation, conductivity, etc.).

[0003] Traditional skin materials have limitations in noise reduction performance, mainly manifested in the following ways: relying on a single sound-absorbing or sound-insulating layer makes it difficult to cover a wide range of noise; the limited surface area of ​​the adhesive interface leads to insufficient overall material durability; the multi-layer composite process is prone to interface defects, affecting the noise reduction effect; and the strong acid electrolyte used in traditional electrolytic treatment processes is prone to causing environmental pollution. Summary of the Invention

[0004] To address the problem mentioned in the background art that traditional skin materials rely on a single sound-absorbing or sound-insulating layer for noise reduction performance, making it difficult to cover a wide frequency range of noise, this invention provides a noise-reducing skin material and its preparation method. By modifying the skin layer, sound-absorbing layer, sound-insulating layer, and functionalized adhesive layer, the invention solves the problems of poor noise reduction effect, complex production process, and environmental unfriendliness of traditional skin materials, providing a new type of high-efficiency, environmentally friendly noise-reducing skin material with good mechanical properties and its preparation method.

[0005] The specific technical solution of the present invention is as follows: a noise reduction skin material, comprising a skin layer, a sound-absorbing layer, a sound-insulating layer and a functionalized adhesive layer, wherein the surface of the skin layer is formed into a porous oxide film by electrolytic oxidation treatment.

[0006] This invention utilizes a multi-layered structural design consisting of a skin layer, a sound-absorbing layer, and a sound-insulating layer. The porous oxide film generated by electrolytic oxidation of the skin layer not only enhances sound wave scattering and interface impedance matching but also provides excellent surface conditions for subsequent bonding.

[0007] This invention provides a method for preparing a noise-reducing skin material, comprising the following steps: 1) Immerse the aluminum-based alloy skin in an electrolyte containing sulfuric acid and a modifier for 10-15 minutes to generate a porous oxide film coating skin layer. 2) Inject the polyurethane mixture into a mold and pressurize it to form a sound-absorbing layer. The temperature of the inner layer of the mold is set to 80~85℃, and the temperature of the outer layer of the mold is set to 40~50℃. 3) Graphene nanosheets were dispersed in a silica aerogel matrix, stirred evenly, and then freeze-dried. Piezoelectric ceramic particles were added to obtain a sound insulation layer. 4) Apply adhesive to the porous oxide film surface on the skin layer obtained in step 1), and heat-press to cure, to obtain the noise reduction skin material.

[0008] This invention employs a multi-layered structural design consisting of a skin layer, a sound-absorbing layer, and a sound-insulating layer. The skin layer, with its porous oxide film generated through electrolytic oxidation, enhances sound wave scattering and interface impedance matching. The sound-absorbing layer, with its gradient pores, effectively absorbs broadband noise, improving noise reduction efficiency. The sound-insulating layer, composed of nanoscale silica aerogel and graphene, combines high acoustic impedance with low density, further enhancing the material's isolation effect against high-frequency noise. This results in a noise attenuation rate exceeding 30 dB in the 50-5000 Hz frequency range.

[0009] As a preferred option, sodium citrate is used as the modifier.

[0010] Preferably, the amount of modifier added is 2-5 wt%.

[0011] Further, in step 1), the aluminum-based alloy is one of 6061 aluminum alloy, 5052 aluminum alloy or 7075 aluminum alloy.

[0012] Furthermore, the electrolyte has a pH of 2.0 to 3.5 and an electrolysis temperature of 20 to 40°C. The electrolyte of this invention uses sodium citrate as a modifier to replace traditional strong acids, reducing the risk of environmental pollution. Moreover, by precisely controlling the current density and electrolysis time, the directional growth of porous membranes is achieved, which not only improves the safety and environmental friendliness of the production process, but also ensures the consistency of product quality.

[0013] Furthermore, the porous oxide film has a pore size of 50~500nm and a thickness of 50~200μm.

[0014] Further, in step 2), the polyurethane mixture includes 3-5 wt% CO2, 0.5-1 wt% sodium bicarbonate, and 94-98 wt% polyurethane matrix.

[0015] Furthermore, in step 3), the amount of graphene nanosheets added is 5-7% of the weight of the silica aerogel matrix, and the amount of piezoelectric ceramic particles added is 1-5% of the weight of the silica aerogel matrix. This invention uses an environmentally friendly adhesive containing nano-titanium dioxide reinforcement, which utilizes capillary action to penetrate into the micropores to form an anchoring effect, significantly increasing the bonding area and improving the bonding strength, thereby enhancing the overall strength and durability of the material and extending the service life of the product.

[0016] Furthermore, the thickness of the sound insulation layer is 1.2~1.5mm.

[0017] Further, the adhesive in step 4) includes: 70-75% epoxy resin, 20-25% nano titanium dioxide, and 8-10% toughening agent.

[0018] Furthermore, the temperature for hot pressing curing is 80~120℃.

[0019] Compared with the prior art, the beneficial effects of the present invention are: 1) This invention uses a multi-layered structural design consisting of a skin layer, a sound-absorbing layer, and a sound-insulating layer. The porous oxide film generated by electrolytic oxidation of the skin layer enhances sound wave scattering and interface impedance matching. The sound-absorbing layer has gradient pores that can effectively absorb broadband noise and improve noise reduction efficiency. The sound-insulating layer is composed of nano-scale silica aerogel and graphene, which has both high acoustic impedance and low density characteristics, further enhancing the material's isolation effect against high-frequency noise, so that the noise attenuation rate of the material in the frequency range of 50-5000Hz reaches more than 30dB.

[0020] 2) The electrolyte of this invention uses sodium citrate as a modifier to replace traditional strong acids, which reduces the risk of environmental pollution. Furthermore, by precisely controlling the current density and electrolysis time, the directional growth of porous membranes is achieved, which not only improves the safety and environmental friendliness of the production process, but also ensures the consistency of product quality.

[0021] 3) This invention uses an environmentally friendly adhesive containing nano-titanium dioxide reinforcement, which utilizes capillary action to penetrate into the micropores to form an anchoring effect, significantly increasing the bonding area and improving the bonding strength, thereby enhancing the overall strength and durability of the material and extending the product's service life. Detailed Implementation

[0022] All features disclosed in this specification, or all steps in all disclosed methods or processes, may be combined in any way, except for mutually exclusive features and / or steps.

[0023] The present invention will be further described below with reference to embodiments.

[0024] Example 1 A method for preparing a noise-reducing skin material: 1) Preparation of the epidermis The 6061 aluminum alloy casing was immersed in a sulfuric acid electrolyte containing 2 wt% sodium citrate. The pH of the electrolyte was adjusted to 2.5, the temperature was controlled at 30℃, and the current density was 0.8 A / dm³. 2 Electrolysis for 12 minutes under certain conditions generates a porous oxide film with a pore size of 300 nm and a thickness of 150 μm, resulting in a skin layer coated with the porous oxide film.

[0025] 2) Preparation of sound-absorbing layer A polyurethane mixture containing 4wt% CO2, 0.8wt% sodium bicarbonate, and 95.2wt% polyurethane matrix was injected into a mold. The outer layer temperature of the mold was set to 45℃ and the inner layer temperature was set to 82℃. A gradient pore sound-absorbing layer with a thickness of 1.3mm was prepared by pressure molding process, wherein the outer layer porosity was 85% and the inner layer porosity was 45%.

[0026] 3) Preparation of sound insulation layer Next, 6 wt% graphene nanosheets were dispersed in a silica aerogel matrix, stirred evenly, and then freeze-dried to form a sound insulation layer with a thickness of 1.2 mm. 3 wt% piezoelectric ceramic particles were added to form a sound insulation layer with a thickness of 1.2 mm.

[0027] 4) Synthetic noise-reducing skin material Finally, an adhesive consisting of 72% epoxy resin, 23% nano titanium dioxide, and 5% toughening agent is coated onto the surface of the porous oxide film in step 1). The adhesive is then allowed to penetrate into the micropores using capillary action. The hot-press curing temperature is 100℃, the pressure is 0.8 MPa, and the curing time is 45 minutes, ultimately yielding the noise-reducing skin material.

[0028] 5) Performance Testing The performance of the noise reduction skin material obtained in step 4) is tested.

[0029] Comparative Example 1 The only difference between this comparative example and Example 1 is that, in this comparative example, no oxide layer is applied to the surface of the epidermis; all other processes are the same as in Example 1. The specific steps are as follows: A method for preparing a skin material: 1) Preparation of the epidermis The outer skin is made of 6061 aluminum alloy.

[0030] 2) Preparation of sound-absorbing layer A polyurethane mixture containing 4wt% CO2, 0.8wt% sodium bicarbonate, and 95.2wt% polyurethane matrix was injected into a mold. The outer layer temperature of the mold was set to 45℃ and the inner layer temperature was set to 82℃. A gradient pore sound-absorbing layer with a thickness of 1.3mm was prepared by pressure molding process, wherein the outer layer porosity was 85% and the inner layer porosity was 45%.

[0031] 3) Preparation of sound insulation layer Next, 6 wt% graphene nanosheets were dispersed in a silica aerogel matrix, stirred evenly, and then freeze-dried to form a sound insulation layer with a thickness of 1.2 mm. 3 wt% piezoelectric ceramic particles were added to form a sound insulation layer with a thickness of 1.2 mm.

[0032] 4) Synthetic noise-reducing skin material Finally, an adhesive consisting of 72% epoxy resin, 23% nano titanium dioxide, and 5% toughening agent was applied to the surface of the 6061 aluminum alloy in step 1). The adhesive was allowed to penetrate into the micropores by capillary action. The hot-press curing temperature was 100℃, the pressure was 0.8 MPa, and the curing time was 45 minutes, resulting in the final noise-reducing skin material.

[0033] 5) Performance Testing The performance of the noise-reducing skin material obtained in step 4) was tested. g / cm 3 Table 1. Influence of the porous oxide film in the outer skin layer on the performance of the noise-reducing skin material. Epidermal characteristics Noise reduction performance (50-5000Hz) Bond strength / MPa Material density / g·cm-3 Example 1 Contains porous oxide film >30dB 5.2 0.78 Comparative Example 1 Non-porous oxide film 20~25dB 3.5 0.82 The data in Table 1 show that the lack of oxidation treatment on the skin layer leads to a decrease in both the noise reduction performance and adhesive strength of the final noise-reducing skin material. The reasons are speculated to be as follows: the skin layer without oxidation treatment has a smooth surface and lacks a porous structure, resulting in weak sound wave scattering ability and a significant decrease in the sound absorption coefficient, thus reducing the noise reduction performance; the microporous structure without an oxide layer prevents the adhesive from penetrating into the substrate to form an anchoring effect, reducing the adhesive area by about 60%, and the adhesive layer is prone to delamination due to interfacial stress concentration in high-temperature or humid environments.

[0034] Example 2 A method for preparing a noise-reducing skin material: 1) Preparation of the epidermis The 5052 aluminum alloy casing was immersed in a sulfuric acid electrolyte containing 2 wt% sodium citrate. The pH of the electrolyte was adjusted to 3.0, the temperature was controlled at 25℃, and the current density was 0.8 A / dm³. 2 Electrolysis for 12 minutes under certain conditions generates a porous oxide film with a pore size of 300 nm and a thickness of 150 μm, resulting in a skin layer coated with the porous oxide film.

[0035] 2) Preparation of sound-absorbing layer A polyurethane mixture containing 3wt% CO2, 1wt% sodium bicarbonate, and 96.0wt% polyurethane matrix was injected into a mold. The outer layer temperature of the mold was set to 40℃ and the inner layer temperature was set to 80℃. A gradient pore sound-absorbing layer with a thickness of 1.3mm was prepared by pressure molding process, wherein the outer layer porosity was 75% and the inner layer porosity was 38%.

[0036] 3) Preparation of sound insulation layer Next, 6 wt% graphene nanosheets were dispersed in a silica aerogel matrix, stirred evenly, and then freeze-dried to form a sound insulation layer with a thickness of 1.2 mm. 3 wt% piezoelectric ceramic particles were added to form a sound insulation layer with a thickness of 1.2 mm.

[0037] 4) Synthetic noise-reducing skin material Finally, an adhesive consisting of 72% epoxy resin, 23% nano titanium dioxide, and 5% toughening agent is coated onto the surface of the porous oxide film in step 1). The adhesive is then allowed to penetrate into the micropores using capillary action. The hot-press curing temperature is 100℃, the pressure is 0.8 MPa, and the curing time is 45 minutes, ultimately yielding the noise-reducing skin material.

[0038] 5) Performance Testing The performance of the noise reduction skin material obtained in step 4) is tested.

[0039] Example 3 A method for preparing a noise-reducing skin material: 1) Preparation of the epidermis The 7075 aluminum alloy casing was immersed in a sulfuric acid electrolyte containing 3 wt% sodium citrate. The pH of the electrolyte was adjusted to 2.0, the temperature was controlled at 30℃, and the current density was 0.8 A / dm³. 2 Electrolysis for 10 minutes under certain conditions generates a porous oxide film with a pore size of 50 nm and a thickness of 100 μm, resulting in a skin layer coated with the porous oxide film.

[0040] 2) Preparation of sound-absorbing layer A polyurethane mixture containing 4wt% CO2, 0.8wt% sodium bicarbonate, and 95.2wt% polyurethane matrix was injected into a mold. The outer layer temperature of the mold was set to 45℃ and the inner layer temperature was set to 82℃. A gradient pore sound-absorbing layer with a thickness of 1.5mm was prepared by pressure molding process, wherein the outer layer porosity was 85% and the inner layer porosity was 45%.

[0041] 3) Preparation of sound insulation layer Next, 5 wt% graphene nanosheets were dispersed in a silica aerogel matrix, stirred evenly, and then freeze-dried to form a sound insulation layer with a thickness of 1.2 mm. 1 wt% piezoelectric ceramic particles were added to form a sound insulation layer with a thickness of 1.5 mm.

[0042] 4) Synthetic noise-reducing skin material Finally, an adhesive consisting of 70% epoxy resin, 25% nano titanium dioxide, and 5% toughening agent is coated onto the surface of the porous oxide film in step 1). The adhesive is then allowed to penetrate into the micropores using capillary action. The hot-press curing temperature is 100℃, the pressure is 0.8 MPa, and the curing time is 45 minutes, ultimately yielding the noise-reducing skin material.

[0043] 5) Performance Testing The performance of the noise reduction skin material obtained in step 4) is tested.

[0044] The embodiments described above merely illustrate specific implementation methods of this application, and while the descriptions are detailed and specific, they should not be construed as limiting the scope of protection of this application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the technical solution of this application, and these modifications and improvements all fall within the scope of protection of this application.

Claims

1. A noise-reducing skin material, characterized in that, The skin layer, the sound absorption layer, the sound insulation layer and the functional adhesive layer are included.

2. A method of producing the noise-reducing skin material according to claim 1, characterized in that The method comprises the following steps: 1) immersing the aluminum alloy skin into an electrolyte containing sulfuric acid and a modifier for electrolysis of 10-15 min to form a porous oxide film coated skin layer; 2) injecting polyurethane mixture into a mold to obtain a sound absorption layer by pressure forming, wherein the temperature of the inner layer of the mold is set to 80-85 DEG C, and the temperature of the outer layer of the mold is set to 40-50 DEG C; 3) dispersing graphene nanosheet in silica aerogel matrix, stirring uniformly, then freeze-drying, adding piezoelectric ceramic particles to obtain a sound insulation layer; 4) coating the adhesive on the surface of the porous oxide film of the skin layer obtained in step 1), and hot-pressing and curing to obtain a noise reduction skin material.

3. The method of claim 2, wherein the noise-reducing skin material is prepared by the steps of: In step 1), the aluminum alloy is one of 6061 aluminum alloy, 5052 aluminum alloy or 7075 aluminum alloy.

4. A method of manufacturing a noise-reducing skin material according to claim 2 or 3, characterized in that, The pH of the electrolyte is 2.0-3.5, and the electrolysis temperature is 20-40 DEG C.

5. The method of claim 4, wherein the noise-reducing skin material is prepared by the steps of: The pore size of the porous oxide film is 50-500 nm, and the thickness is 50-200 μm.

6. The method of claim 2, wherein the noise-reducing skin material is prepared by the steps of: In step 2), the polyurethane mixture includes CO2 5wt%, sodium bicarbonate 0.5-1wt% and polyurethane matrix 94-98wt%.

7. The method of claim 2, wherein the noise reducing skin material is prepared by the steps of: In step 3), the addition amount of graphene nanosheet is 5-7% of the weight of silica aerogel matrix, and the addition amount of piezoelectric ceramic particles is 1-5% of the weight of silica aerogel matrix.

8. The method of claim 7, wherein the noise-reducing skin material is prepared by the steps of: The thickness of the sound insulation layer is 1.2-1.5 mm.

9. The method of claim 2, wherein the noise reducing skin material is prepared by the steps of: In step 4), the adhesive includes: epoxy resin 70-75%, nano-titanium dioxide 20-25%, and toughening agent 8-10%.

10. The method of claim 2, wherein the noise reducing skin material is prepared by the steps of: The temperature of hot-pressing and curing is 80-120 DEG C.