A light-weight anti-aging gearbox acoustic package for new energy vehicles and a preparation method thereof

Abstract

The application discloses a light-weight aging-resistant gearbox acoustic package for a new energy vehicle and a preparation method thereof, and belongs to the technical field of sound insulation materials. The gearbox acoustic package comprises a needled cotton layer, a PA / PE film and a PU soft layer. The raw materials of the PU soft layer comprise the following components in parts by weight: 70-80 parts of diisocyanate, 80-100 parts of polyether polyol, 20-35 parts of modified polysiloxane, 0.5-1 part of a chain extender, 35-110 parts of methyl methacrylate, 0.3-1.5 parts of ethylene glycol dimethacrylate, 0.01-0.2 parts of an initiator, 1-3 parts of a surfactant, 0.5-1 part of a catalyst and 1-3 parts of a foaming agent. The gearbox acoustic package has the advantages of sound absorption, vibration isolation and heat and oxygen aging resistance, the components of the PU foaming layer material are optimized, the comprehensive performance of the gearbox acoustic package is ensured, and the gearbox acoustic package can be applied to the field of new energy vehicles.

Description

Technical Field

[0001] This invention relates to the field of sound insulation materials technology, specifically to a lightweight, aging-resistant acoustic package for a transmission used in new energy vehicles and its preparation method. Background Technology

[0002] With the continuous development of modern industrial society and the continuous improvement of the automotive industry, more and more passenger car customers no longer only focus on driving performance, but also put forward higher and higher requirements for NVH (noise, vibration and harshness) performance. The high-frequency noise brought by permanent magnet synchronous motors and gearboxes has become a priority issue for major OEMs. As a result, the solution of laying acoustic packages containing PU foam composite layers has emerged to reduce noise.

[0003] Currently, acoustic packaging materials mainly include EVA rubber layers, PET felt, and PU foam. EVA rubber layers are rigid and primarily used for sound insulation, while PU foam is a soft layer primarily used for sound absorption. EVA has good sound insulation, but in practical applications, the operating temperature of a gearbox can reach up to 105℃, causing EVA rubber to soften and deform, leading to sound leakage. In this case, the product's sound insulation function is reduced or even lost. PU foam has numerous interconnected micropores extending from the surface to the interior. When sound waves strike the surface of the porous material, they cause air vibration within the micropores. Due to frictional resistance, viscous resistance of the air, and thermal conduction, a significant portion of the sound energy is converted into heat energy, thus achieving sound absorption. However, the low mechanical strength, poor surface quality, and low thermal stability of PU foam still need to be addressed. With the trend towards lightweighting in automobiles, acoustic packaging is gradually moving towards "absorption instead of insulation," replacing high-density sound insulation materials with low-density porous sound-absorbing materials. Lightweight and high-performance materials are increasingly favored and are being used more widely in the automotive field. As a component of the acoustic package, the sound insulation pad must be lightweight while also possessing excellent acoustic performance, thereby providing occupants with a superior riding environment and sound quality experience. Summary of the Invention

[0004] In order to overcome the shortcomings of the existing technology, the present invention provides a lightweight and aging-resistant acoustic package for new energy vehicle transmissions and its preparation method, which has the advantages of sound absorption, vibration isolation and aging resistance while meeting the requirements of lightweighting.

[0005] The purpose of this invention is to provide a lightweight, aging-resistant acoustic package for a transmission in new energy vehicles, comprising a needle-punched cotton layer, a PA / PE film, and a PU soft layer; the raw materials of the PU soft layer, by weight, include the following components: 70-80 parts of diisocyanate, 80-100 parts of polyether polyol, 20-35 parts of modified polysiloxane, 0.5-1 part of chain extender, 35-110 parts of methyl methacrylate, 0.3-1.5 parts of ethylene glycol dimethacrylate, 0.01-0.2 parts of initiator, 1-3 parts of surfactant, 0.5-1 part of catalyst, and 1-3 parts of foaming agent;

[0006] The modified polysiloxane is prepared by:

[0007] S1. Octamethylcyclotetrasiloxane, aminosilane coupling agent and hexamethyldisiloxane in a molar ratio of 20:(0.1~1):(0.2~0.5) are used to generate amino-modified branched polysiloxane through ring-opening polymerization and hydrolysis condensation reaction.

[0008] S2. Add pyromellitic dianhydride, which is equivalent to 1.1 to 1.3 times the molar amount of aminosilane coupling agent, and carry out amidation and imidation reactions with amino-modified branched polysiloxane to obtain modified polysiloxane.

[0009] In one specific embodiment, the weight of the needle-punched cotton is 1100–1400 g / m³. 2 The basis weight of the PA / PE film is 80-200 g / m³. 2 The density of the PU soft layer is 50-80 kg / m³. 3 .

[0010] In one specific embodiment, the chain extender is selected from one or more of ethylene glycol, 1,4-butanediol, glycerol, trimethylolpropane, 4,4'-diphenylmethane diisocyanate, and hexamethylene diisocyanate isocyanurate trimer; the aminosilane coupling agent is selected from one or more of 3-aminopropyltriethoxysilane and γ-aminopropylmethyldiethoxysilane.

[0011] In one specific embodiment, the initiator is benzoyl peroxide; the catalyst comprises a gel catalyst and a foaming catalyst in a mass ratio of (8-10):1, wherein the gel catalyst is triethylenediamine and the foaming catalyst is bis(2-dimethylaminoethyl) ether.

[0012] In one specific embodiment, the number-average molecular weight of the modified polysiloxane is 5000–20000 g / mol.

[0013] In one specific embodiment, the isocyanate is selected from one or more of toluene diisocyanate, diphenylmethane diisocyanate, and polymethylene polyphenyl isocyanate; the polyether polyol is selected from one or more of pentaerythritol ether, ethylenediamine polyether, and glycerol polyether.

[0014] In one specific embodiment, the foaming agent is water or azodicarbonamide; the surfactant is an organosilicone surfactant.

[0015] In one specific embodiment, the hydroxyl value is tested according to the standard GB / T12008.3-2009.

[0016] In one specific embodiment, the PU foam material further includes 0.1-5 parts of an antioxidant; the antioxidant is at least one of hindered phenolic antioxidants, hindered amine antioxidants, thioester antioxidants, and phosphite antioxidants.

[0017] In one specific embodiment, the needle-punched cotton layer is flame-retardant needle-punched cotton.

[0018] This invention also includes a method for preparing a lightweight, aging-resistant acoustic package for a transmission used in new energy vehicles, comprising the following steps:

[0019] S1. Needle-punched cotton and PA / PE film are laid in a mold, and then hot-pressed and punched at 210℃ to obtain a needle-punched cotton-PA / PE film hard layer.

[0020] S2. In a reactor under dry nitrogen protection, polyether polyol, modified polysiloxane, surfactant and catalyst are mixed and stirred evenly according to the ratio. Diisocyanate and chain extender are added and stirred and polymerized at 60-90℃ for 20-30 minutes to obtain polyurethane prepolymer. The reaction is terminated by rapid cooling.

[0021] S3. In another dry nitrogen-protected reactor, methyl methacrylate monomer, ethylene glycol dimethacrylate and initiator are mixed and stirred evenly according to the ratio. The mixture is stirred at 60-90°C until the conversion rate reaches 10%-15%, and the reaction is terminated by rapid cooling.

[0022] S4. Mix the polyurethane prepolymer obtained in step S2 with the mixture obtained in step S3 at room temperature, then react at 70-90°C for 1-2 hours. Add the foaming agent and stir evenly. Pour the mixture into a mold pre-laid with needle-punched cotton and PA / PE film hard layer, shake and flatten it, place it in an oven, and react with gradient temperature to obtain an acoustic package composed of needle-punched cotton-PA / PE film hard layer and polyurethane foam soft layer. Demold the acoustic package and store it at room temperature for 3 days to obtain a lightweight and aging-resistant gearbox acoustic package.

[0023] In one specific embodiment, the gradient temperature increases are 55°C, 65°C, 85°C, and 110°C, with each temperature reacting for 1 to 4 hours.

[0024] This invention also protects the application of the lightweight, aging-resistant acoustic package for a new energy vehicle transmission in new energy vehicles.

[0025] Beneficial effects

[0026] This invention provides a lightweight and aging-resistant acoustic package for transmissions in new energy vehicles. By replacing the traditional EVA rubber layer with needle-punched cotton and modifying the PU foam material of the PU soft layer, the sound absorption effect and aging resistance of the PU soft layer are improved. This results in an acoustic package with the advantages of being lightweight and having high thermal stability, meeting the automotive industry's demand for weight reduction, and producing a lightweight and aging-resistant transmission acoustic package.

[0027] The addition of modified polysiloxane acts as a nucleation site, reducing pore size and increasing semi-open porosity, thus endowing the material with excellent sound absorption and flexibility. This improves the mechanical strength of the PU soft layer, allowing the acoustic package to deform to a certain extent without breaking under impact or vibration. Furthermore, the cross-linked silicone rubber particles formed by branched polysiloxane provide high damping properties, dissipating sound wave energy through molecular motion, further enhancing sound absorption. The remaining anhydride end groups after the reaction of pyromellitic dianhydride with amino-modified polysiloxane can undergo imidization with diisocyanate, further increasing the polyurethane cross-linking density and uniformly dispersing the polysiloxane structure into the PU foam network via covalent cross-linking. The introduction of imide groups further improves the thermal stability of the PU soft layer, enabling the acoustic package to maintain stable physical and chemical properties in the high operating temperature environment of new energy vehicle transmissions, preventing decomposition and deformation, and ensuring long-term stable noise reduction performance.

[0028] In addition, the addition of methyl methacrylate, ethylene glycol dimethacrylate and initiator forms an interpenetrating polymer network with the polyurethane prepolymer. The thermally stable PMMA structure improves the thermal stability and viscoelasticity of the PU soft layer, thereby further improving the thermal stability and sound absorption capacity of PU.

[0029] The acoustic package produced by this invention can exhibit good sound absorption performance over a wide frequency range, effectively absorbing noise of various frequencies generated by new energy transmissions under different operating conditions, and has good application prospects. Attached Figure Description

[0030] Figure 1 Infrared spectra of amino-modified branched polysiloxane and modified polysiloxane 1. Detailed Implementation

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

[0032] Unless otherwise specified, the experimental methods used in the embodiments are conventional methods, and the materials and reagents used are commercially available unless otherwise specified.

[0033] The raw materials used in the examples and comparative examples are described below:

[0034] Needle-punched cotton: 1400g / m² 2 Purchased from Dongguan Zhicheng Fiber;

[0035] PA / PE film: HcForm-MB, surface density 100g / m³ 2 Purchased from Anhui Hengchang New Materials Co., Ltd.

[0036] Diisocyanate: CG-3701S, containing 75wt% diphenylmethane diisocyanate MDI and 25wt% TDI, NCO content 37±0.5%, Kumho Petrochemical;

[0037] Polyether polyol: PPG-6000, hydroxyl value 28±2%, weight average molecular weight 6000g / mol, average functionality 3, Kumho Petrochemical;

[0038] Catalysts: Gel catalyst DABCO 33LV, containing 33% triethylenediamine and 67% dipropylene glycol, Air Products and Chemicals, Inc.; foaming catalyst DABCO BL17, an acid-blocked catalyst containing 70% bis(2-dimethylaminoethyl) ether, diluted with 30% dipropylene glycol, Air Products and Chemicals, Inc.; the mass ratio of gel catalyst to foaming catalyst is 9:1.

[0039] Surfactant: Organosilicon surfactant, L-3002, Momentive;

[0040] Aminosilane coupling agent: 3-aminopropyltriethoxysilane, commercially available;

[0041] Modified polysiloxane 1: Self-made, preparation method is as follows:

[0042] S1. Under a nitrogen atmosphere, 2 mol of octamethylcyclotetrasiloxane and 0.1 mol of... 3-Aminopropyltriethoxysilane and 1.2 mol tetramethylammonium hydroxide (in the form of a 10% aqueous solution) were mixed and heated to 90℃. The mixture was stirred at 150 r / min for 4 h. Then, 0.05 mol hexamethyldisiloxane was added, and the mixture was stirred for another 35 min. Finally, the mixture was heated to 150℃ and reacted for 8 min. Low-boiling substances were removed under a vacuum of -0.09 MPa. After cooling, 0.1 mol / L dilute hydrochloric acid was slowly added to the system to neutralize it to pH 7. An equal volume of deionized water was added to the mixture, and the mixture was stirred for 30 min. The mixture was then allowed to stand and separate into layers. The aqueous layer was removed, and the mixture was washed with water 2-3 times until the aqueous layer had a pH of 7 and no chloride ions were detected (no precipitate was found when tested with silver nitrate solution). The washed product was dried with anhydrous sodium sulfate or magnesium sulfate for 2-4 hours. The desiccant was removed by filtration, and the product was dried at 60-80℃ and a vacuum of ≤1 kPa for 1 hour to obtain amino-modified branched polysiloxane.

[0043] S2. Under a nitrogen atmosphere, dissolve 0.12 mol of pyromellitic dianhydride in 50 ml of dimethyl sulfoxide (DMSO). Disperse the amino-modified branched polysiloxane obtained in step S1 in 30 ml of DMSO. Mix and stir, then heat to 80°C and react for 4-6 hours. Continue heating to 150°C and react for 2-4 hours. After the reaction is complete, cool the system to 100°C and stir for 1-2 hours under a vacuum of ≤1 kPa. Distill off most of the DMSO, and add 3-5 times the volume of n-hexane to the remaining system. Stir for 30 minutes to allow the product to precipitate. After standing, filter, collect the precipitate, discard the filtrate, and wash the precipitate again with a small amount of cold toluene 2-3 times. Collect the washed precipitate, disperse the precipitate in deionized water (solid-liquid ratio of 1:5), stir for 30 minutes, allow to stand and separate into layers, discard the water layer, and repeat the water washing until the pH of the water layer is 7. After water washing, add anhydrous sodium sulfate or magnesium sulfate to dry for 2-4 hours, filter to remove the desiccant, and finally dry at 60-80℃ and vacuum degree ≤1kPa for 1 hour to obtain modified polysiloxane 1.

[0044] Modified polysiloxanes 2-5: The difference between them and modified polysiloxane 1 lies in the amount of raw materials added, as shown in Table 1.

[0045] Table 1. Molar amounts of each component added and physical property tests of modified polysiloxanes 1-5

[0046]

[0047] The number-average molecular weight and molecular weight distribution coefficient (Mw / Mn) of the amino-modified branched polysiloxanes were determined using gel permeation chromatography (GPC); the mass fraction of acid anhydrides in the modified polysiloxanes was determined using acid-base titration. The molecular structures of the amino-modified branched polysiloxanes and modified polysiloxane 1 were determined using infrared spectroscopy. Figure 1 As shown in the infrared spectrum, the NH2 characteristic peak is more obvious in the amino-modified branched polysiloxane, but the -NH2 peak in the modified polysiloxane is significantly weakened, and the peak is lowered in the 1860-1750 cm⁻¹ range. -1 The characteristic peak of acid anhydride appears at 1337 cm⁻¹, and at the same time at 1337 cm⁻¹. -1 Characteristic peaks of CN were detected at 1069 and 730 cm⁻¹. -1 The presence of a characteristic peak of CNC nearby indicates that pyromellitic dianhydride successfully reacted with the amino-modified branched polysiloxane, and that active anhydride sites exist in the modified polysiloxane. However, a small amount of unreacted amino groups may still exist.

[0048] Polyether siloxane: SYLGARD TM OFX-5211, with a hydroxyl value of 1.08% by mass, was purchased from Dow Chemical.

[0049] Chain extender: Hexamethylene diisocyanate isocyanurate trimer, CAS: 3779-63-3, 99.8%, NCO content is 21.8±0.3%, Wanhua Chemical;

[0050] Methyl methacrylate: 99.5%, Shanghai Maclean Biochemical Technology Co., Ltd.;

[0051] Ethylene glycol dimethacrylate: 98%, Shanghai Maclean Biochemical Technology Co., Ltd.;

[0052] Initiator: Benzoyl peroxide; 98%, Shanghai Maclean Biochemical Technology Co., Ltd.

[0053] Foaming agent: purified water, Watsons;

[0054] Unless otherwise specified, all components and raw materials used in the embodiments and comparative examples of this invention are commercially available, and the same type of components and raw materials are used in each parallel experiment.

[0055] Examples and Comparative Examples

[0056] A lightweight, aging-resistant acoustic package for a transmission in new energy vehicles includes a needle-punched cotton layer, a PA / PE membrane, and a PU soft layer. The average thickness of the multilayer structure is 25 mm, wherein the needle-punched cotton layer has a thickness of 2.1 mm, and the PA / PE membrane has a thickness of 100 μm. The specific preparation method is as follows:

[0057] S1. Needle-punched cotton and PA / PE film are laid in a mold, and then hot-pressed and punched at 210℃ to obtain a needle-punched cotton-PA / PE film hard layer.

[0058] S2. In a reactor under dry nitrogen protection, polyether polyol, modified polysiloxane, surfactant and catalyst are mixed in the proportions shown in Table 2, stirred at 1700 rpm for 10 minutes, diisocyanate and chain extender are added and stirred and polymerized at 75°C for 20 minutes to obtain polyurethane prepolymer.

[0059] S3. In another dry nitrogen-protected reactor, distilled methyl methacrylate monomer, ethylene glycol dimethacrylate and benzoyl peroxide are added and stirred under reflux at 550 rpm. The reactor is then immersed in a water bath and heated to 78°C. The mixture is stirred until the benzoyl peroxide is completely dissolved. The reaction progress is monitored by adding a drop of the mixture to isopropanol and observing the precipitation of solid PMMA. The reaction continues until the conversion rate reaches 10%-15%, and then the reaction is terminated by rapid cooling.

[0060] S4. The polyurethane prepolymer obtained in step S2 is mixed with the mixture obtained in step S3 at room temperature for 20 minutes, and then reacted at 80°C for 1 hour. At the end of the reaction, foaming agent water is added to the mixture. After a few minutes, the mixture is poured into a mold pre-laid with needle-punched cotton and a PA / PE film hard layer, and placed in an oven for final polymerization at 55°C, 65°C, 85°C, and 110°C, respectively, for 1 hour at each temperature range. This yields an acoustic package composed of a needle-punched cotton-PA / PE film hard layer and a polyurethane foam soft layer. The acoustic package is then demolded and stored at room temperature (relative humidity: 50±10%) for 3 days to obtain a lightweight, aging-resistant gearbox acoustic package. The apparent density of the polyurethane foam soft layer is tested to be 62±1.00 kg / m³. 3 .

[0061] Table 2 Raw material ratios (parts by weight) for polyurethane foam flexible layers

[0062]

[0063]

[0064] The acoustic packages prepared in Examples 1-7 and Comparative Examples 1-5 were subjected to the following performance tests, and the results are shown in Table 3.

[0065] 1. Cell Diameter: The morphology (pores and voids) of the polyurethane matrix was observed using a scanning electron microscope (SEM, model SNE-3000M, SEC Ltd., accelerating voltage 30kV). SEM samples were sputtered with gold using a gold sputtering system (model MCM 100, SEC Ltd.) before imaging. The average pore diameter was obtained using Image Pro Plus software (Media Cybernetics).

[0066] 2. Sound insulation test: The test was conducted according to GB / T18696.2-2002 standard. The sample thickness was 25mm, the sound source frequency was 400Hz, and the sound source noise was 90dB. The amount of noise received was measured. The greater the noise level, the worse the noise reduction effect. At the same time, the test environment was in a temperature change process of 30℃~60℃ to simulate the ambient temperature change process of daily driving.

[0067] 3. Vibration damping test: The damping of a material is generally measured by the magnitude of the loss tangent tanδ (or loss factor, damping factor). The loss factor tanδ (damping factor) is tested according to dynamic mechanical analysis (DMA).

[0068] 4. Heat resistance aging: After aging at 100°C for 1000 hours, the products of the examples and comparative examples were subjected to shock absorption tests to measure the retention rate of the loss factor tanδ of the materials after heat aging.

[0069] Table 3 Performance test results of the acoustic package

[0070]

[0071] As can be seen from Examples 1-3, the anhydride content of the modified polysiloxane, i.e. the amount of aminosilane coupling agent added, needs to be kept within a certain range. Otherwise, if there are too many active sites of anhydride and the crosslinking density of polyurethane is too high, it will affect the viscoelasticity.

[0072] As can be seen from Comparative Example 3, when the molecular weight of the modified polysiloxane (controlled by the end-capping agent hexamethyldisiloxane) is kept in the range of 5000 to 20000 g / mol, it has a better nucleation effect on PU foam material, resulting in smaller pore diameters and better sound absorption.

[0073] As can be seen from Examples 2, 4, 5 and Comparative Examples 2, 5, the amount of improved polysiloxane added needs to be controlled within a reasonable range. Adding too much will cause agglomeration and affect the foaming effect.

[0074] As can be seen from Examples 2, 6, and 7, the addition of polymethyl methacrylate increases the diameter of the foam pores, but improves the viscoelasticity and aging resistance of the PU soft layer.

[0075] The preferred embodiments of the present invention disclosed above are merely illustrative of the invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the invention to the specific implementations described. Clearly, many modifications and variations can be made based on the content of this specification. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to better understand and utilize the invention. The invention is limited only by the claims and their full scope and equivalents.

Claims

1. A light weight, ageing resistant gearbox acoustic pack for new energy vehicles, characterized in that, It comprises a needle-punched cotton layer, a PA / PE film and a PU soft layer; the raw materials of the PU soft layer comprise the following components in parts by weight: diisocyanate 70-80 parts, polyether polyol 80-100 parts, modified polysiloxane 20-35 parts, chain extender 0.5-1 part, methyl methacrylate 35-110 parts, ethylene glycol dimethacrylate 0.3-1.5 parts, initiator 0.01-0.2 parts, surfactant 1-3 parts, catalyst 0.5-1 part and foaming agent 1-3 parts; The preparation method of the modified polysiloxane is: S1. Octamethylcyclotetrasiloxane, amino silane coupling agent and hexamethyldisiloxane in a molar ratio of 20:(0.1-1):(0.2-0.5) are subjected to ring-opening polymerization and hydrolysis condensation reaction to generate branched polysiloxane modified by amino groups; S2. Phthalic anhydride is added in an amount corresponding to 1.1-1.3 times the molar amount of the amino silane coupling agent to react with the branched polysiloxane modified by amino groups to generate amide and imide, thereby obtaining the modified polysiloxane.

2. The gearbox acoustic package of claim 1, wherein, The needle-punched cotton has a gram weight of 1100-1400 g / m 2 The PA / PE film has a gram weight of 80-200 g / m 2 The PU soft layer has a density of 50-80 kg / m 3 .

3. The gearbox acoustic package of claim 1, wherein, The chain extender is selected from one or more of ethylene glycol, 1,4-butanediol, glycerol, trimethylolpropane, 4,4'-diphenylmethane diisocyanate, hexamethylene diisocyanate isocyanurate trimer; the amino silane coupling agent is selected from one or more of 3-aminopropyl triethoxysilane and gamma-aminopropyl methyldiethoxysilane.

4. The gearbox acoustic package of claim 1, wherein, The initiator is benzoyl peroxide; the catalyst comprises a gel catalyst and a foaming catalyst in a mass ratio of (8-10):1, wherein the gel catalyst is triethylenediamine and the foaming catalyst is bis(2-dimethylaminoethyl) ether.

5. The transmission acoustic package of claim 1, wherein, The number average molecular weight of the modified polysiloxane is 5000-20000 g / mol.

6. The gearbox acoustic package of claim 1, wherein, The isocyanate is selected from one or more of toluene diisocyanate, diphenylmethane diisocyanate and polymethylene polyphenyl isocyanate; the polyether polyol is selected from one or more of pentaerythritol ether, ethylenediamine polyether and glycerol polyether.

7. The transmission acoustic package of claim 1, wherein, The foaming agent is water or azodicarbonamide; the surfactant is a silicone surfactant.

8. A method for preparing a light-weight, aging-resistant acoustic package for a transmission of a new energy vehicle according to any one of claims 1-7, characterized in that, The method comprises the following steps: S1. The needle-punched cotton and the PA / PE film are laid in a mold, and then subjected to hot pressing at 210 DEG C to form a needle-punched cotton-PA / PE film hard layer; S2. In a reaction kettle under dry nitrogen protection, the polyether polyol, the modified polysiloxane, the surfactant and the catalyst are mixed and stirred uniformly according to the proportion, and then the diisocyanate and the chain extender are added and stirred at 60-90 DEG C for 20-30 minutes to obtain a polyurethane prepolymer, and the reaction is terminated by rapid cooling; S3. In another reaction kettle under dry nitrogen protection, the methyl methacrylate monomer, the ethylene glycol dimethacrylate and the initiator are mixed and stirred uniformly according to the proportion, and then subjected to stirring reaction at 60-90 DEG C until the conversion rate reaches 10%-15%, and the reaction is terminated by rapid cooling; S4. The polyurethane prepolymer obtained in step S2 is mixed with the mixture obtained in step S3 at room temperature, then reacted at 70-90°C for 1-2 hours, a foaming agent is added and stirred uniformly, the mixture is poured into a mold pre-laid with needle-punched cotton and a PA / PE film hard layer, shaken and leveled, placed in an oven, and reacted with gradient temperature, to obtain a needle-punched cotton-PA / PE film hard layer and polyurethane foaming soft layer composite acoustic package, the acoustic package is demolded, stored at room temperature for 3 days, to obtain a light-weight aging-resistant gearbox acoustic package.

9. The production method according to claim 8, wherein The gradient temperature is 55°C, 65°C, 85°C and 110°C, and each temperature is reacted for 1-4 hours.

10. Use of a light-weight aging-resistant gearbox acoustic package according to any one of claims 1-7 in a new energy vehicle.

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