Acoustic metamaterial with sound absorption and insulation and noise reduction structural design and preparation method of acoustic metamaterial

Abstract

The invention provides an acoustic metamaterial with sound absorption and insulation and noise reduction structural design and a preparation method thereof. The acoustic metamaterial is prepared from polyetherimide, granular rubber and an organic solvent. The weight part ratio of the polyetherimide to the granular rubber to the organic solvent is 1: (1.4-1.9): (0.3-0.9). Wherein a proper proportion of particle rubber is added, so that a particle dispersed phase is formed in the prepared sound absorption and insulation noise reduction film structure, the overall mechanical property of the film is enhanced by the particle dispersed phase, low-frequency noise can be refracted and reflected, and the particle dispersed phase forms a same-frequency resonance effect in the sound absorption and insulation noise reduction film structure; therefore, the effect of dissipating sound wave energy is achieved, and the low-frequency noise absorption and suppression effect of the sound absorption and insulation noise reduction film structure is improved. For low-frequency noise of 100-400 Hz, the sound absorption coefficient of the sound absorption and insulation noise reduction film structure is not lower than 0.85, and the sound insulation index is not lower than 14 dB.

Description

Technical Field

[0001] The invention belongs to the technical field of preparation of sound-absorbing, insulating and noise-reducing materials, and specifically relates to an acoustic metamaterial with a sound-absorbing, insulating and noise-reducing structural design and a preparation method thereof. Background Art

[0002] Noise pollution has become one of the important factors affecting people's quality of life. Among them, the porous sound-absorbing material prepared based on polyetherimide belongs to the traditional dissipative high-frequency and broadband noise reduction material. The porous sound-absorbing material is usually used in substation equipment to absorb the high-frequency and broadband random noise (such as fan noise, etc.) generated by the substation equipment, and its sound absorption and noise reduction effect is obvious. In addition, the above-mentioned sound-absorbing and noise reduction material has high hardness and toughness, and the mechanical processing method is complicated and costly, which affects the overall sound absorption effect and material stability.

[0003] However, the above-mentioned sound-absorbing and noise-reducing materials cannot effectively absorb or suppress the low-frequency noise generated by the substation equipment, especially the above-mentioned sound-absorbing and noise-reducing materials have unsatisfactory noise reduction effects on the low-frequency noises of 100Hz and 400Hz generated by the oil-immersed substation equipment. Summary of the invention

[0004] The purpose of the present invention is to solve the problem that the existing noise reduction materials have poor sound absorption and noise reduction performance for low-frequency noise.

[0005] The purpose of the present invention is to adopt the following technical solutions to achieve:

[0006] The present invention provides an acoustic metamaterial with a sound absorption, insulation and noise reduction structural design. The raw materials for preparing the acoustic metamaterial include polyetherimide, granular rubber and an organic solvent. In parts by weight, the ratio of the polyetherimide, the granular rubber and the organic solvent is 1:(1.4-1.9):(0.3-0.9).

[0007] Preferably, the ratio of the polyetherimide, the particle rubber and the organic solvent is 1:1.65:0.6.

[0008] Preferably, the particle size of the rubber particles is 20nm-50nm.

[0009] Preferably, the rubber particles are composed of nanographite powder and polyisoprene.

[0010] Preferably, the mass percentage of the nano-graphite powder in the particle rubber is 0.5%-2%.

[0011] Preferably, the organic solvent includes one or more of N-methylpyrrolidone, N,N-dimethylacetamide and N,N-dimethylformamide.

[0012] Based on the same inventive concept, the present invention also provides a method for preparing the acoustic metamaterial with the sound-absorbing, insulating and noise-reducing structure design, comprising: preparing raw materials: weighing polyetherimide, granular rubber and organic solvent in proportion and putting them into a container; preparing casting liquid: heating and dissolving the raw materials in the container and degassing to obtain the casting liquid; preparing thin film: subjecting the casting liquid to scraping and curing treatment to form a cured thin film; film forming treatment: subjecting the cured thin film to exchange treatment with isopropyl alcohol and n-hexane respectively and then drying treatment to obtain a sound-absorbing, insulating and noise-reducing membrane structure.

[0013] Preferably, in the step of preparing the casting solution, the heating temperature of the heating and dissolving is 80° C.-100° C., and the heating time is 10 min-15 min.

[0014] Preferably, in the step of preparing the casting solution, the degassing treatment adopts a vacuum drying oven, the degassing temperature of the vacuum drying oven is set to 40° C.-60° C., and the degassing time is 15 min-20 min.

[0015] Preferably, in the thin film preparation step, the film scraping treatment uses a film scraping machine, and the film scraping thickness of the film scraping treatment is 50 μm-100 μm.

[0016] Preferably, in the film forming step, exchanging the cured film with isopropanol and n-hexane respectively comprises: firstly immersing the cured film in isopropanol with a concentration of 30%-60% and letting it stand for 30min-60min; and then immersing the cured film in n-hexane with a concentration of 20%-30% and letting it stand for 30min-40min.

[0017] Preferably, in the film forming step, the drying process uses an electric blast drying oven, the drying temperature of the electric blast drying oven is set to 25°C-35°C, and the blowing time is 20min-25min.

[0018] Compared with the prior art, the present invention has the following beneficial effects:

[0019] The present invention provides an acoustic metamaterial with a sound absorption, insulation and noise reduction structure design. The raw materials for preparing the acoustic metamaterial include polyetherimide, granular rubber and organic solvent; by weight, the ratio of polyetherimide, granular rubber and organic solvent is 1:(1.4-1.9):(0.3-0.9). In particular, an appropriate proportion of granular rubber is added to the raw materials for preparing the acoustic metamaterial, so that the prepared sound absorption, insulation and noise reduction membrane structure has a particle dispersion phase. On the one hand, the particle dispersion phase enhances the overall mechanical properties of the film, and on the other hand, the particle dispersion phase can refract and reflect 100Hz-400Hz low-frequency noise, and the particle dispersion phase can form a same-frequency resonance effect with the low-frequency noise in the sound absorption, insulation and noise reduction membrane structure, thereby playing a role in dissipating the energy of the sound wave, and improving the absorption and suppression effect of the sound absorption, insulation and noise reduction membrane structure on low-frequency noise.

[0020] Among them, when the surface density of the sound-absorbing, noise-reducing and sound-insulating membrane structure is 10kg / ㎡-30kg / ㎡, the weighted sound insulation is not less than 30dB. In the low-frequency noise range of 100Hz-400Hz, the average sound absorption coefficient of the sound-insulating, noise-reducing membrane structure is not less than 0.85, and the average sound insulation is not less than 14dB. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 Flow chart of the method for preparing the acoustic metamaterial designed for the sound absorbing, isolating and noise reducing structure of the present invention. DETAILED DESCRIPTION

[0022] In order to enable those skilled in the art to better understand the technical solution of the present invention, the preferred solution of the present invention is described below in conjunction with the best embodiment of a specific application. Obviously, the described embodiment is only a part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in the field without creative work are within the scope of protection of the present invention.

[0023] The experimental methods or test methods in the following examples are conventional methods unless otherwise specified; reagents and raw materials are obtained from conventional commercial channels or prepared by conventional methods unless otherwise specified.

[0024] The invention provides an acoustic metamaterial with a sound absorption, insulation and noise reduction structural design. The raw materials for preparing the acoustic metamaterial include polyetherimide, granular rubber and an organic solvent. In parts by weight, the ratio of the polyetherimide, the granular rubber and the organic solvent is 1:(1.4-1.9):(0.3-0.9).

[0025] Among them, an appropriate proportion of granular rubber is added to the raw materials for preparing the acoustic metamaterial, so that the particle dispersed phase formed in the prepared sound-absorbing, insulating and noise-reducing membrane structure is distributed in a particle structure. On the one hand, the particle dispersed phase enhances the overall mechanical properties of the film, and on the other hand, the particle dispersed phase can refract and reflect 100Hz-400Hz low-frequency noise, and the particle dispersed phase particles at different positions in the sound-absorbing, insulating and noise-reducing membrane structure can form a resonance effect with the low-frequency noise, thereby dissipating the sound wave energy and improving the sound-absorbing, insulating and noise-reducing membrane structure. The absorption and suppression effect of low-frequency noise.

[0026] Specifically, Figure 1 As shown, the method for preparing the acoustic metamaterial with a sound absorption, insulation and noise reduction structure design of the present invention comprises:

[0027] S1. Prepare raw materials: weigh polyetherimide, rubber particles and organic solvent according to proportion and put them into a container;

[0028] S2, preparation of casting solution: heating, dissolving and degassing the raw materials in the container to obtain casting solution;

[0029] S3, film preparation: the casting liquid is subjected to a scraping treatment and a curing treatment to form a cured film;

[0030] S4. Film-forming treatment: the solidified film is subjected to exchange treatment with isopropyl alcohol and n-hexane respectively and then dried to obtain a sound-absorbing, sound-insulating and noise-reducing membrane structure.

[0031] Specifically, in step S1, in preparing the raw materials, the rubber particles are particles composed of nanographite powder and polyisoprene, the particle size of the particles is 20nm-50nm, wherein the mass percentage of the nanographite powder in the rubber particles is 0.5%-2%. The organic solvent is one or more of N-methylpyrrolidone, N,N-dimethylacetamide and N,N-dimethylformamide.

[0032] It should be noted that by selecting rubber particles of different particle size ranges, the particle dispersed phase particles in the sound-absorbing, noise-insulating and noise-reducing membrane structure increase the refraction, reflection and resonance energy dissipation of sound waves. In addition, the nano-graphite powder mainly plays a role in adjusting the mechanical properties and weight of the film. Since the sound-absorbing, noise-insulating and noise-reducing membrane structure of the present invention mainly plays a role in sound absorption and insulation through the resonance energy consumption between the membrane structure and the sound waves, the weight of the particle dispersed phase particles is adjusted by adding an appropriate amount of nano-graphite powder to the rubber particles, and the mechanical properties of the film are adjusted by diffusing the nano-graphite powder in the film material, so that the film resonates with sound waves of different frequencies, thereby increasing the dissipation of sound wave energy.

[0033] In step S2, in the preparation of the casting solution, the container is heated and dissolved by heating the raw materials in the container in the casting solution preparation step, and an electric heating furnace is used to heat the container to form a solution. The heating temperature of the electric heating furnace is set to 80°C-100°C, and the heating time is 10min-15min. Finally, the solution in the container is naturally cooled to room temperature.

[0034] It should be noted that, in the above steps, the particle rubber to which the nano-graphite powder is added can maintain its particle state without melting during the heating of the solution.

[0035] The degassing step in the preparation of the casting solution uses a vacuum drying oven to degas the solution in the cooled container. The degassing temperature of the vacuum drying oven is set at 40°C-60°C, the vacuum degree does not exceed 0.01Mpa, and the degassing time is 15min-20min to obtain the degassed casting solution.

[0036] It should be noted that the casting liquid reduces the dissolved gas partial pressure under a vacuum environment, promotes the precipitation of gas in the casting liquid, accelerates the aggregation and floating of bubbles to improve the degassing efficiency, avoids the use of chemical additives, and ensures the quality, density and purity of the prepared membrane material.

[0037] In step S3, the film scraping treatment in the film preparation uses a film scraping machine to scrape a wet film, and the film thickness of the film scraping treatment is 50μm-100μm. The solidification treatment in the film preparation uses a solidification bath pure water to phase transform the wet film scraped by the film scraping machine to form a solidified film.

[0038] The film scraping machine is used to improve the uniformity, flatness and cohesion of the film, ensure the overall consistency of the film when it resonates with the sound wave, and improve the resonance efficiency of the film. The inclination angle between the scraper of the film scraping machine and the coated surface is 50 to 60 degrees. When defects such as bubbles, wrinkles, depressions and scratches appear during the film scraping process, they should be repaired immediately. Scrape 1 to 2 times, and avoid multiple back and forth scraping, otherwise the phenomenon of "dry skin but not dry inside" will appear.

[0039] In step S4, the solidified film is treated with isopropanol and n-hexane exchange, including: firstly, soaking the solidified film in isopropanol with a concentration of 30%-60% and letting it stand for 30min-60min; preferably, letting it stand for 30min-40min, and preferably repeating the process of soaking the solidified film in isopropanol twice. Then, soaking the solidified film in n-hexane with a concentration of 20%-30% and letting it stand for 30min-40min.

[0040] It should be noted that when the solidified film formed by pure water is directly dried, due to the large surface tension of water, the drying process will cause some particles in the solidified film to fall off from the film matrix, resulting in damage to the film structure. The present invention uses isopropyl alcohol and n-hexane solvent exchange to reduce the falling off of particles in the film and the matrix during the drying process of the solidified film. That is, the solidified film is first immersed in isopropyl alcohol, which is mutually soluble in water, so that the residual water in the solidified film is replaced by isopropyl alcohol, and the moisture in the film is removed; then the solidified film is immersed in isopropyl alcohol, and n-hexane is mutually soluble in isopropyl alcohol, so that the isopropyl alcohol in the solidified film is replaced by hexane. The n-hexane solvent has low surface tension and is volatile, and the falling off problem between particles in the film and the matrix is ​​avoided after direct drying.

[0041] After the cured film is immersed in the isopropanol and n-hexane solutions in sequence for exchange treatment, the cured film is dried.

[0042] The drying process uses an electric blast drying oven, the drying temperature of the electric blast drying oven is set at 25°C-35°C, and the blowing time is 20min-25min. After the drying process is completed, a sound-absorbing, insulating and noise-reducing membrane structure is obtained.

[0043] It should also be noted that, unlike the traditional noise reduction film, in the sound absorption and noise reduction film structure prepared by the present invention, the particle rubber and the film matrix form a dense film, rather than a porous film structure. The sound absorption and noise reduction film structure achieves sound absorption and sound insulation effects through the principle of resonance between the film and the particle dispersion phase and the sound wave.

[0044] The acoustic metamaterials with sound absorption, insulation and noise reduction structure designs provided in the following embodiments are all made of the above-mentioned types of raw materials and preparation methods, and the only difference is that the raw material parameters and preparation parameters used in the embodiments are different.

[0045] Examples 1-3

[0046] Specifically, Table 1 is a comparison table of raw material parameters for preparing acoustic metamaterials with sound absorption, insulation and noise reduction structures in Examples 1-3:

[0047] Table 1

[0048]

[0049] It should be noted that the use of N-methylpyrrolidone as the organic solvent in Examples 1-3 is not restrictive, and those skilled in the art may also use N,N-dimethylacetamide and N,N-dimethylformamide as the organic solvent according to practical applications.

[0050] In addition, Table 2 is a comparison table of preparation parameters of acoustic metamaterials with sound absorption, insulation and noise reduction structures in Examples 1-3:

[0051] Table 2

[0052]

[0053]

[0054] Comparative Example 1

[0055] Different from Example 1, in Comparative Example 1, no granular rubber is added, and only polyetherimide and N-methylpyrrolidone are used, and the weight ratio of the two is 1:0.9. Other raw material parameters and preparation parameters are exactly the same as those in Example 1, so they are not repeated here.

[0056] Comparative Example 2

[0057] Different from Example 3, in Comparative Example 3, no granular rubber is added, and only polyetherimide and N-methylpyrrolidone are used, and the weight ratio of the two is 1:0.3. Other raw material parameters and preparation parameters are exactly the same as those in Example 3, so they are not repeated here.

[0058] Test Results

[0059] The surface density, weighted sound insulation, sound insulation of different frequency line spectra and sound absorption coefficient of the sound-absorbing, noise-reducing membrane structures prepared in the above-mentioned Examples 1-3, Comparative Example 1 and Comparative Example 2 were tested.

[0060] It should be noted that the sound absorption coefficient and sound insulation are test results for fixed frequency lines such as 100Hz, 200Hz, 300Hz and 400Hz, and the weighted sound insulation refers to the total sound insulation of the sound-absorbing, sound-insulating and noise-reducing membrane structure after weighted calculation in the frequency band of 20Hz-20000Hz.

[0061] Specifically, Table 3 is a comparison table of the test results of Examples 1-3, Comparative Example 1 and Comparative Example 2:

[0062] Table 3

[0063]

[0064]

[0065] By comparison, it can be seen that in Examples 1-3 of the present invention, when the surface density of the acoustic metamaterial with the sound absorption, insulation and noise reduction structure design is 24kg / ㎡-28kg / ㎡, the weighted sound insulation is not less than 35dB. In the 100Hz-400Hz frequency line spectrum, the average sound absorption coefficient of the acoustic metamaterial with the sound absorption, insulation and noise reduction structure design is not less than 0.85, and the average sound insulation is not less than 14dB.

[0066] The weighted sound insulation and corresponding indexes of the acoustic metamaterials with sound absorption, insulation and noise reduction structure designs of comparative examples 1 and 2 are lower than those of embodiments 1 to 3 of the present invention. In other words, the acoustic metamaterials with sound absorption, insulation and noise reduction structure designs prepared by the present invention can have a significant sound absorption and noise reduction effect on 100Hz-400Hz low-frequency noise.

[0067] It should be noted that when the ratio of polyetherimide, granular rubber and N-methylpyrrolidone in the raw materials drops to below 1:1.4:0.3, due to the decrease in the content of the particle dispersed phase in the film, the film density decreases and the thickness becomes thinner, the particle dispersed phase in the film can no longer refract, reflect and resonate the energy dissipation effect of sound waves, resulting in a significant decrease in the sound absorption and insulation performance.

[0068] When the ratio of polyetherimide, granular rubber and N-methylpyrrolidone in the raw material ratio rises to 1:1.9:0.9 or above, the content of the particle dispersed phase in the film is too high, resulting in the film density being too high and the thickness becoming thicker. The film that bears the resonance effect cannot bear the high-quality particle dispersed phase, and the particle dispersed phase produces a "swelling and falling" effect on the film. That is, the sound wave cannot excite the film as a whole, and the film as a whole cannot resonate with the sound wave, which seriously affects the film's energy dissipation effect on the sound wave, resulting in a significant decrease in the sound absorption performance.

[0069] Therefore, when preparing the acoustic metamaterial with a sound absorption, insulation and noise reduction structure design, adding an appropriate proportion of granular rubber can play a good role in sound absorption and noise reduction of low-frequency noise. In comparison, the acoustic metamaterial with a sound absorption, insulation and noise reduction structure design prepared in Example 2 has the best sound absorption and noise reduction effect.

[0070] The above are merely embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention are included in the scope of the claims of the present invention to be approved.

Claims

1. An acoustic metamaterial with a sound absorption, insulation and noise reduction structure design, characterized in that: The raw materials for preparing the acoustic metamaterial include polyetherimide, granular rubber and an organic solvent; In parts by weight, the ratio of the polyetherimide, the particle rubber and the organic solvent is 1:(1.4-1.9):(0.3-0.9).

2. The acoustic metamaterial with a sound absorption, insulation and noise reduction structure design as claimed in claim 1, characterized in that: The ratio of the polyetherimide, the particle rubber and the organic solvent is 1:1.65:0.

6.

3. The acoustic metamaterial with a sound absorption, insulation and noise reduction structure design as claimed in claim 1, characterized in that: The particle size of the rubber particles is 20nm-50nm.

4. The acoustic metamaterial with a sound absorption, insulation and noise reduction structure design as claimed in claim 1, characterized in that: The particle rubber consists of nano graphite powder and polyisoprene.

5. The acoustic metamaterial with a sound absorption, insulation and noise reduction structure design as claimed in claim 4, characterized in that: The mass percentage of the nano graphite powder in the particle rubber is 0.5%-2%.

6. The acoustic metamaterial with a sound absorption, insulation and noise reduction structure design as claimed in claim 1, characterized in that: The organic solvent includes one or more of N-methylpyrrolidone, N,N-dimethylacetamide and N,N-dimethylformamide.

7. A method for preparing an acoustic metamaterial with a sound absorption, insulation and noise reduction structure design as claimed in any one of claims 1 to 6, characterized in that: include: Prepare raw materials: weigh polyetherimide, rubber particles and organic solvent according to proportion and put them into a container; Preparation of casting solution: heating, dissolving and degassing the raw materials in the container to obtain the casting solution; Film preparation: subjecting the casting solution to scraping and curing treatment to form a cured film; Film forming treatment: the solidified film is subjected to exchange treatment with isopropyl alcohol and n-hexane respectively and then dried to obtain a sound absorbing, insulating and noise reducing membrane structure.

8. The method for preparing the acoustic metamaterial with a sound absorption, insulation and noise reduction structure design according to claim 7, characterized in that: In the step of preparing the casting solution, the heating temperature of the heating and dissolving is set at 80° C.-100° C., and the heating time is 10 min-15 min.

9. The method for preparing the acoustic metamaterial with a sound absorption, insulation and noise reduction structure design according to claim 7, characterized in that: In the step of preparing the casting solution, the degassing treatment adopts a vacuum drying oven, the degassing temperature of the vacuum drying oven is set at 40° C.-60° C., and the degassing time is 15 min-20 min.

10. The method for preparing the acoustic metamaterial with a sound absorption, insulation and noise reduction structure design according to claim 7, characterized in that: In the film preparation step, the film scraping treatment uses a film scraping machine, and the film thickness of the film scraping treatment is 50μm-100μm.

11. The method for preparing the acoustic metamaterial with a sound absorption, insulation and noise reduction structure design according to claim 7, characterized in that: In the film forming step, exchanging the cured film with isopropanol and n-hexane respectively comprises: firstly immersing the cured film in isopropanol with a concentration of 30%-60% and letting it stand for 30min-60min; and then immersing the cured film in n-hexane with a concentration of 20%-30% and letting it stand for 30min-40min.

12. The method for preparing the acoustic metamaterial with a sound absorption, insulation and noise reduction structure design according to claim 7, characterized in that: In the film forming step, the drying process uses an electric blast drying oven, the drying temperature of the electric blast drying oven is set at 25°C-35°C, and the blowing time is 20min-25min.

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