Sound absorption and noise reduction material and application thereof in special acoustic space

Abstract

The invention relates to a sound-absorbing and noise-reducing material and application thereof in a special acoustic space, in particular to the technical field of sound-absorbing and noise-reducing materials, and raw materials for preparing the sound-absorbing and noise-reducing material are a macromolecular resin base material and aramid nanofiber aerogel; the raw materials for preparing the polymer resin base material comprise 80-90 wt% of epoxy resin and 10-20 wt% of hollow glass beads; the aramid fiber nanofiber aerogel is subjected to cross-linking enhancement treatment of waterborne polyurethane and zirconate. The sound-absorbing and noise-reducing material provided by the invention has the advantages of light weight, pressure resistance, good sound-absorbing and sound-insulating performance and the like, and can be well applied to special acoustic spaces such as aviation passenger cabins, movie theaters, hospitals or recording studios and the like.

Description

Technical Field

[0001] The present invention belongs to the technical field of sound-absorbing and noise-reducing materials, and in particular relates to a sound-absorbing and noise-reducing material and its application in special acoustic spaces. Background Art

[0002] Sound-absorbing and noise-reducing materials are widely used in many fields, such as the construction industry, automotive industry, electronics industry, and aviation industry. Most sound-absorbing and noise-reducing materials are loose and porous materials. Their sound absorption mechanism is that sound waves penetrate into the pores of the material, and the pores are mostly open holes that penetrate each other internally. They are subjected to friction and viscous resistance of air molecules, and the mechanical vibration of small fibers, thereby converting sound energy into heat energy, thereby achieving the effect of sound absorption and noise reduction.

[0003] Currently, most porous noise-reducing materials used on the market are organic sound-absorbing materials, such as asphalt sheets, polyester fiber pads, fiberglass blankets, and butyl rubber. However, with technological development and innovation, new sound-absorbing materials are constantly emerging. For example, textile composite noise-reducing materials, such as porous sound-absorbing composite noise-reducing materials, porous and resonant composite noise-reducing materials, and porous and damping composite noise-reducing materials, are undergoing in-depth research and development.

[0004] As a new type of porous material, nanofiber aerogel has broad application prospects in adsorption, filtration, shock absorption, thermal insulation and noise reduction due to its low density, high porosity and large specific surface area. However, the mechanical properties of aerogel products obtained by the traditional nanofiber aerogel production process are weak and cannot withstand high pressure, which limits the scope of its practical application. Summary of the Invention

[0005] The purpose of the present invention is to provide a sound-absorbing and noise-reducing material and its application in special acoustic spaces in order to solve the above problems.

[0006] The present invention achieves the above-mentioned purpose through the following technical solutions: The present invention provides a sound-absorbing and noise-reducing material. The raw materials for preparing the sound-absorbing and noise-reducing material are a polymer resin substrate and aramid nanofiber aerogel; the raw materials for preparing the polymer resin substrate include 80-90wt% of epoxy resin and 10-20wt% of hollow glass microspheres; the aramid nanofiber aerogel is subjected to a cross-linking and reinforcement treatment of water-based polyurethane and zirconate.

[0007] As a further optimization solution of the present invention, the mass ratio of the waterborne polyurethane to the zirconate is (2-6):1.

[0008] As a further optimization solution of the present invention, the cross-linking enhancement treatment is specifically: (1) The aramid nanofiber hydrogel is crushed and placed in a tert-butyl alcohol solution for microwave heat treatment. After the microwave heat treatment, a mixed solution of aqueous polyurethane and zirconate is added and stirred to obtain an aramid hydrogel suspension; (2) The aramid hydrogel suspension is first vacuum filtered, then molded and frozen to obtain a hydrogel frozen body, and finally the hydrogel frozen body is vacuum freeze-dried.

[0009] As a further optimization scheme of the present invention, the preparation method of the aramid nanofiber hydrogel is: dry aramid and potassium hydroxide are added together into a dimethyl sulfoxide solvent to prepare an aramid nanofiber dispersion, and the aramid nanofiber dispersion is added into an ethanol solution for gelation treatment to obtain the hydrogel.

[0010] As a further optimization solution of the present invention, the concentration of the aramid nanofiber dispersion is 0.5-1.0 wt %.

[0011] As a further optimization solution of the present invention, the mass ratio between the amount of the aramid and the total amount of the waterborne polyurethane and zirconate is 1:1.

[0012] As a further optimization scheme of the present invention, in step (2), the process conditions of microwave heat treatment are: microwave power is 100-500W, heating to 100-150°C at 2-4°C / min, and lasting for 3-5 minutes.

[0013] As a further optimization scheme of the present invention, in step (3), vacuum freeze drying is to place the hydrogel frozen body in a vacuum freeze dryer and dry it for 48 hours at a vacuum pressure of 25-30 Pa and a temperature of -35-40°C.

[0014] As a second aspect of the present invention, there is also provided an application of any of the above-mentioned sound-absorbing and noise-reducing materials in a special acoustic space, wherein the special acoustic space refers to an activity space with an average acoustic transmission loss (STL) greater than 40dB in the range of 800-2000Hz.

[0015] As a further optimization solution of the present invention, the activity space is at least one of an airline cabin, a theater, a hospital or a recording studio.

[0016] The beneficial effects of the present invention are: (1) The sound-absorbing and noise-reducing material provided by the present invention comprises a polymer resin substrate and an aramid nanofiber aerogel composited on the substrate by an adhesive. The aramid nanofiber aerogel is treated with water-based polyurethane and zirconate to enhance the structural stability of the aramid nanofiber aerogel and adjust the internal pores. The prepared aramid nanofiber aerogel has excellent noise reduction performance and also improves the disadvantage of traditional aerogel materials such as weak mechanical properties and inability to withstand high pressure.

[0017] (2) The sound-absorbing and noise-reducing material prepared by the present invention has a lower density than commercially available glass wool, polyurethane sponge and SO2 aerogel felt, and has the advantage of being lightweight. In addition, it has good sound absorption and sound insulation properties and can be well applied to special acoustic spaces such as aircraft cabins, theaters, hospitals or recording studios. DETAILED DESCRIPTION

[0018] The present application is described in further detail below. It is necessary to point out that the following specific implementation methods are only used to further illustrate the present application and cannot be understood as limiting the scope of protection of the present application. Technicians in this field can make some non-essential improvements and adjustments to the present application based on the above application content.

[0019] The invention provides a sound-absorbing and noise-reducing material, which comprises a polymer resin substrate and an aramid nanofiber aerogel composited on the polymer resin substrate via an adhesive.

[0020] Furthermore, the aramid nano-aerogel is prepared according to the following preparation method: (1) 2 g of dried aramid and 2 g of potassium hydroxide were added to 196-396 mL of dimethyl sulfoxide solvent, and 4 mL of deionized water was added dropwise. The mixture was stirred at room temperature for 24 h to prepare an aramid nanofiber dispersion with a concentration of 0.5-1.0 wt%. Subsequently, the aramid nanofiber dispersion was added to a 25% by volume ethanol solution for gelation to obtain an aramid nanofiber hydrogel.

[0021] (2) Using waterborne polyurethane and zirconate to crosslink and reinforce aramid nanofiber hydrogel, specifically: First, the aramid nanofiber hydrogel is broken into blocks and placed in a 25wt% tert-butanol solution to replace the dimethyl sulfoxide solvent for 24 hours, with the solution replaced every 6 hours. Subsequently, the aramid nanofiber hydrogel is placed in an appropriate amount of 25wt% tert-butanol solution for microwave heat treatment with a microwave power of 100-500W, and the temperature is increased to 100-150℃ at 2-4℃ / min for 3-5 minutes. After the microwave heat treatment, a mixed solution of aqueous polyurethane and zirconate with a concentration of 40wt% is added to ensure that the mass ratio between the amount of aramid and the total amount of aqueous polyurethane and zirconate is 1:1, and the aramid hydrogel suspension is obtained by magnetic stirring.

[0022] Then, the aramid hydrogel suspension is vacuum filtered, and then placed in a silicone mold for molding, and then frozen to obtain a hydrogel frozen body. Finally, the hydrogel frozen body is vacuum freeze-dried at a vacuum pressure of 25-30Pa and a temperature of -35-40°C for 48 hours.

[0023] Furthermore, the polymer resin matrix includes 80-90% epoxy resin and 10-20% hollow glass microspheres in terms of mass percentage. The preparation method is to mix the epoxy resin and the hollow glass microspheres in proportion and then injection mold them. The injection molding temperature is 170-180°C, the injection molding pressure is 400-600 bar, the holding temperature is 40-45°C, and the size of the hollow glass microspheres is 100-200 μm.

[0024] Finally, the prepared aramid nanofiber aerogel is compounded on a polymer resin substrate through an adhesive to obtain the sound-absorbing and noise-reducing material.

[0025] The beneficial effects of the present invention are described below through specific examples.

[0026] Example 1. Preparation of aramid nanofiber aerogel The preparation method of aramid nanofiber aerogel is as follows: (1) 2 g of dried aramid and 2 g of potassium hydroxide were added to 196 mL of dimethyl sulfoxide solvent, and 4 mL of deionized water was added dropwise. The mixture was stirred at room temperature for 24 h to prepare an aramid nanofiber dispersion with a concentration of 1.0 wt%. Subsequently, the aramid nanofiber dispersion was added to a 25% by volume ethanol solution for gelation to obtain an aramid nanofiber hydrogel.

[0027] (2) Using waterborne polyurethane and zirconate to crosslink and reinforce aramid nanofiber hydrogel, specifically: First, the aramid nanofiber hydrogel was broken into blocks and placed in a 25wt% tert-butanol solution to replace the dimethyl sulfoxide solvent for 24 hours, with the solution replaced every 6 hours. Subsequently, the aramid nanofiber hydrogel was placed in an appropriate amount of 25wt% tert-butanol solution for microwave heat treatment with a microwave power of 100W, and the temperature was increased to 100℃ at 2℃ / min for 5 minutes. After the microwave heat treatment, a mixed solution of aqueous polyurethane and zirconate with a concentration of 40wt% was added to ensure that the mass ratio between the amount of aramid and the total amount of aqueous polyurethane and zirconate was 1:1, and the aramid hydrogel suspension was obtained by magnetic stirring.

[0028] Then, the aramid hydrogel suspension obtained in step (2) is vacuum filtered and then placed in a silica gel mold for molding, which is then frozen to obtain a completely frozen hydrogel. Finally, the completely frozen hydrogel is vacuum freeze-dried at a vacuum pressure of 30 Pa and a temperature of -35°C for 48 hours to obtain the aramid nanofiber aerogel.

[0029] To explore the influence of preparation process of aramid nanofiber aerogel on its performance.

[0030] First, the cross-linking enhancement agent used in the preparation method was adjusted according to Table 1.

[0031] Table 1. Composition design of cross-linking strengthening agent ; Note: In the table, “+” represents use; “-” represents not use; Group A-6 means no cross-linking enhancement agent treatment.

[0032] According to the composition design of the cross-linking reinforcing treatment agent given in Table 1, aramid nanofiber aerogels A-1 to A-6 were prepared according to the above preparation method.

[0033] Subsequently, the preparation process of aramid nanofiber aerogel was adjusted as follows: Aramid nanofiber aerogel A-7: Based on the cross-linking enhancement agent selected for A-2, during preparation, in step (2), microwave heating treatment is not performed.

[0034] Aramid nanofiber aerogel A-8: Based on the cross-linking enhancement agent selected in A-2, during preparation, in step (2), the cross-linking enhancement agent solution is first added and then microwave heating treatment is performed.

[0035] The comprehensive noise reduction performance of sound absorption and sound insulation of aramid nanofiber aerogels A-1 to A-8 was tested.

[0036] The test method is as follows: using an acoustic impedance tube with a diameter of 100mm, the sound absorption performance and acoustic transmission loss of aramid nanofiber aerogels A-1 to A-8 at different frequencies were tested. All tested samples were cylindrical, 20mm thick and 100mm in diameter. During the test, a random standing sound wave was generated within the tube. The sound pressure level at the corresponding position was measured using multiple microphone probes close to the tested sample. The acoustic performance of the material was evaluated by analyzing the emission and transmission of the sound wave on the material surface, and the sound absorption performance and transmission loss of the material were then calculated.

[0037] Table 2 shows a comparison of the average sound absorption coefficients of A-1 to A-8 in the 800-4000 Hz range (the main distribution area of ​​daily traffic noise and human voices), as well as the average acoustic transmission loss (STL) of A-1 to A-8 in the 800-2000 Hz range under the preset 90 dB SPL condition.

[0038] Table 2. Test results of comprehensive noise reduction performance of sound absorption and sound insulation of A-1 to A-8 ; The results in the table show that different cross-linking reinforcing agents have different effects on the sound absorption and sound insulation performance of aramid nanofiber aerogels. Comparing A-1 to A-3, the difference lies in the different mass ratios of waterborne polyurethane to zirconate in the cross-linking reinforcing agent. As the mass ratio increases, the sound absorption performance of the material improves, but after exceeding 4:1, its sound absorption performance decreases. When the mass ratio of waterborne polyurethane to zirconate is 6:1, the optimal sound insulation performance is achieved, and the acoustic transmission loss reaches 42dB. In addition, from A-4 to A-5, it can be seen that the effect of using waterborne polyurethane or zirconate alone on improving the sound absorption and sound insulation performance of the material is not as good as the combined effect of the two. Finally, from A-7 to A-8, it can be seen that the timing of microwave heat treatment during the preparation of aramid nanofiber aerogels will also affect their sound absorption and sound insulation performance.

[0039] Further mechanical testing was conducted on samples A-1 through A-8. Specifically, the compressive strength of the materials was tested using an electronic universal material testing machine. All tested samples were cylindrical, 20mm thick and 100mm in diameter. The samples were placed in the center of the test platform and vertical pressure was applied. The changes in compressive stress and Young's modulus were measured from 0-80% strain.

[0040] The results are shown in Table 3.

[0041] Table 3. Test results of comprehensive noise reduction performance of sound absorption and sound insulation of A-1 to A-8 ; From the results in the table, it can be seen that different cross-linking reinforcing agents have different effects on the mechanical properties of aramid nanofiber aerogel. Comparing A-1 to A-3, the difference is that the mass ratio of water-based polyurethane to zirconate in the cross-linking reinforcing agent is different. As the mass ratio increases, the compressive stress of the material increases, and the corresponding Young's modulus also increases accordingly.

[0042] Furthermore, A-4 to A-5 show that using waterborne polyurethane or zirconate alone is less effective than their combined effect in increasing the compressive stress and Young's modulus of the material. Finally, A-7 to A-8 show that the timing of microwave heat treatment during the preparation of aramid nanofiber aerogels also affects the compressive stress and Young's modulus of the material.

[0043] Example 2: Preparation of sound-absorbing and noise-reducing materials First, a polymer resin substrate was prepared by mixing 90% epoxy resin and 10% hollow glass microspheres according to mass percentage and then injection molding to obtain the polymer resin substrate. The injection molding temperature was 180°C, the injection molding pressure was 400 bar, the holding temperature was 45°C, the size of the hollow glass microspheres was 100 μm, and the thickness of the polymer resin substrate was 10 mm.

[0044] Then, the aramid nanofiber aerogels A-2 and A-3 of Example 1 were respectively bonded on both sides of the polymer resin substrate prepared above by adhesive to obtain a sound-absorbing and noise-reducing material.

[0045] The density comparison of the sound-absorbing and noise-reducing material of the present invention and commercially available glass wool, polyurethane sponge and SO2 aerogel felt under the same volume was measured, and the sound absorption and sound insulation comprehensive noise reduction performance of the sound-absorbing and noise-reducing material of the present invention and commercially available glass wool, polyurethane sponge and SO2 aerogel felt were measured according to the method disclosed in Example 1. The results are shown in Table 4.

[0046] Table 4. Test results statistics ; As can be seen from Table 4, the sound-absorbing and noise-reducing material prepared by the present invention has a lower density than commercially available glass wool, polyurethane sponge and SO2 aerogel felt, and has the advantage of being lightweight. In addition, from the comprehensive noise reduction performance data of sound absorption and sound insulation, it can be seen that the sound-absorbing and noise-reducing material of the present invention has good sound absorption and sound insulation performance, and can be well applied to special acoustic spaces such as aircraft cabins, theaters, hospitals or recording studios.

[0047] The above embodiments merely illustrate several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that a person skilled in the art would be able to make numerous variations and improvements without departing from the spirit of the present invention, and all such variations and improvements fall within the scope of protection of the present invention.

Claims

1. A sound-absorbing and noise-reducing material, characterized by: The raw materials for preparing the sound-absorbing and noise-reducing material are a polymer resin substrate and aramid nanofiber aerogel; the raw materials for preparing the polymer resin substrate include 80-90wt% epoxy resin and 10-20wt% hollow glass microspheres; the aramid nanofiber aerogel is subjected to a cross-linking and reinforcement treatment with water-based polyurethane and zirconate.

2. The sound-absorbing and noise-reducing material according to claim 1, characterized in that: The mass ratio of the waterborne polyurethane to the zirconate is (2-6):

1.

3. The sound-absorbing and noise-reducing material according to claim 1, characterized in that: The cross-linking enhancement treatment is specifically: (1) The aramid nanofiber hydrogel is crushed and placed in a tert-butyl alcohol solution for microwave heat treatment. After the microwave heat treatment, a mixed solution of aqueous polyurethane and zirconate is added and stirred to obtain an aramid hydrogel suspension; (2) The aramid hydrogel suspension is first vacuum filtered, then molded and frozen to obtain a hydrogel frozen body, and finally the hydrogel frozen body is vacuum freeze-dried.

4. The sound-absorbing and noise-reducing material according to claim 3, characterized in that: The preparation method of the aramid nanofiber hydrogel is as follows: dry aramid and potassium hydroxide are added into a dimethyl sulfoxide solvent to prepare an aramid nanofiber dispersion, and the aramid nanofiber dispersion is added into an ethanol solution for gelation to obtain the hydrogel.

5. The sound-absorbing and noise-reducing material according to claim 4, characterized in that: The concentration of the aramid nanofiber dispersion is 0.5-1.0 wt %.

6. The sound-absorbing and noise-reducing material according to claim 4, characterized in that: The mass ratio of the aramid fiber to the total amount of the waterborne polyurethane and zirconate is 1:

1.

7. The sound-absorbing and noise-reducing material according to claim 1, characterized in that: In step (2), the process conditions of microwave heat treatment are: microwave power is 100-500W, heating to 100-150°C at 2-4°C / min, and lasting for 3-5 minutes.

8. The sound-absorbing and noise-reducing material according to claim 1, characterized in that: In the step (3), vacuum freeze drying is to place the hydrogel frozen body in a vacuum freeze dryer and dry it for 48 hours at a vacuum pressure of 25-30 Pa and a temperature of -35-40°C.

9. Use of the sound-absorbing and noise-reducing material according to any one of claims 1 to 8 in a special acoustic space, characterized in that: The special acoustic space refers to an activity space in which the average acoustic transmission loss STL in the range of 800-2000 Hz is greater than 40 dB.

10. The use according to claim 9, characterized in that The activity space is at least one of an airline cabin, a theater, a hospital or a recording studio.