Titanium-silicon molecular sieve agglomerate sound-absorbing material, and preparation method and application thereof

Abstract

The application belongs to the technical field of inorganic porous materials and acoustics, and provides a titanium-silicon molecular sieve aggregate sound-absorbing material, a preparation method and application thereof; the molar ratio of silicon and titanium in the framework of the sound-absorbing material is 25:1-100:1; the morphology is an aggregate formed by aggregation of basic particles, the size of the aggregate is 200-1000 nm, and the bulk density is 0.52 g / cm 3 ~0.70 g / cm 3 The application obtains the titanium-silicon molecular sieve aggregate sound-absorbing material with specific multi-level pore structure and high bulk density by precisely regulating the silicon-titanium ratio and the synthesis process. The sound-absorbing material exhibits excellent performance in the field of acoustics, especially in the preparation of sound-absorbing materials for the rear cavity of a loudspeaker, can effectively reduce the resonance frequency, and has good anti-aging ability.

Description

Technical Field

[0001] This invention belongs to the field of inorganic porous materials and acoustic technology, specifically relating to a titanium-silicon molecular sieve aggregate sound-absorbing material, its preparation method, and its acoustic applications. Background Technology

[0002] Currently, portable electronic devices are becoming increasingly thinner and smaller, which places stringent demands on the space occupied by their internal components. As a key acoustic component, the performance of the speaker is directly related to the volume of its rear cavity. Compression of the rear cavity volume will lead to an increase in the low-frequency resonant frequency (F0), severely degrading sound quality, especially low-frequency performance.

[0003] To improve acoustic performance without increasing physical space, the industry commonly employs filling the rear cavity of loudspeakers with porous sound-absorbing materials (such as molecular sieves) to increase the acoustic equivalent volume and thus reduce the harmonic degradation effect (F0). The performance of molecular sieves is closely related to their chemical composition, pore structure, and physical morphology (such as morphology and bulk density). While traditional high silica-to-alumina ratio (SAR) ZSM-5 molecular sieves possess some hydrophobicity, their bulk density is typically low (approximately 0.3-0.4 g / cm³), limiting the vibrational mass they can provide within a confined space and restricting the potential for improved harmonic degradation. Furthermore, the applicant has found that the morphology of conventional molecular sieves (such as single crystals or disordered large particles) affects their filling uniformity and gas transport efficiency.

[0004] Titanium silicate molecular sieves (such as TS-1) have been extensively studied in the field of catalysis, but their application in acoustics has not been fully explored. Therefore, there is an urgent need to develop a new type of molecular sieve material to achieve superior acoustic performance and long-term stability in micro-speakers. Summary of the Invention

[0005] To address the above problems, this invention provides a titanium-silicon molecular sieve agglomerate sound-absorbing material, its preparation method, and its acoustic applications.

[0006] To achieve the above objectives, the technical solution of the present invention is as follows: A titanium-silicon molecular sieve agglomerate sound-absorbing material has a silicon to titanium molar ratio (Si / Ti) of 25:1 to 100:1 in its framework. The morphology of the sound-absorbing material is a secondary structure composed of aggregates of basic particles (primary particles), i.e., aggregates. The size of the aggregates ranges from 200 to 1200 nm, and the bulk density of the sound-absorbing material is 0.52 g / cm³. 3 ~0.70 g / cm 3 .

[0007] This submicron-scale aggregate morphology, composed of nanoscale basic particles, creates abundant interparticle mesopores at the microscopic level, which is conducive to the formation of a high specific surface area and an optimized hierarchical pore network. At the same time, this dense packing method helps to achieve a high packing density. High packing density means that more mass can be filled within the limited volume of the speaker's rear cavity, thereby generating a stronger inertial load on the diaphragm and enhancing the acoustic tuning potential.

[0008] Furthermore, the molar ratio of silicon to titanium is 25:1 to 60:1.

[0009] Furthermore, the size of the aggregates is 200-500 nm.

[0010] Furthermore, the basic particle size that makes up the aggregates is 10-150 nm.

[0011] Furthermore, the size of the elementary particles is 10-80 nm.

[0012] Furthermore, the sound-absorbing material has an MFI structure, and its micropore size ranges from 0.5 to 0.6 nm, which is consistent with the characteristic pore size of the MFI structure; its mesopore (mainly interparticle pores) size ranges from 2 to 10 nm. This multi-level pore system with both micropores and mesopores is beneficial for the rapid transport and storage of air molecules.

[0013] Furthermore, the static adsorption capacity of the titanium-silicon molecular sieve for water is ≤1.5%, indicating that it has good hydrophobicity, which helps to suppress the influence of environmental moisture on the acoustic properties of the material, thus possessing excellent anti-aging potential.

[0014] This invention also provides a method for preparing the aforementioned titanium-silicon molecular sieve agglomerate sound-absorbing material, comprising the following steps: uniformly mixing a silicon source, a titanium source, a template agent, a surfactant, and water to form an initial gel mixture; then carrying out a hydrothermal crystallization reaction at 150-180℃ for 24-48 hours; after the reaction, performing solid-liquid separation, washing, drying, and calcination on the product to obtain the desired titanium-silicon molecular sieve agglomerate sound-absorbing material. By controlling the reaction conditions (temperature, time), the nucleation, growth, and subsequent controllable agglomeration of nanoscale basic particles are guided, thereby forming the target morphology.

[0015] Further, the silicon source is selected from tetraethyl orthosilicate, the titanium source is selected from tetrabutyl titanate, the template agent is selected from tetrapropylammonium hydroxide, and the surfactant is selected from at least one of Tween-20, Tween-40, or Tween-60.

[0016] Further, the preparation method specifically includes the following process: under stirring conditions, silicon source and titanium source are added dropwise to template agent solution, and surfactant is added and stirring is continued to form a uniform gel; then the gel is transferred to crystallization reaction device and statically crystallized at crystallization temperature for a certain time, and the size and degree of aggregation of basic particles are controlled by controlling crystallization temperature and time; after crystallization, the product is centrifuged, repeatedly washed with deionized water until neutral, dried at 90-120℃ for 6-12 hours, and then calcined in a muffle furnace at 500-650℃ for 2-8 hours to completely remove organic template agent, thereby obtaining titanium silicon molecular sieve aggregate sound-absorbing material sample.

[0017] Furthermore, the molar ratio of the silicon source, titanium source, and template agent is 1:(0.01~0.04):(0.2~0.4), wherein the silicon source is calculated as SiO2 and the titanium source is calculated as TiO2.

[0018] Further, the amount of surfactant added is 0.5wt% to 5.0wt% of the mass of SiO2 in the silicon source; preferably 0.5wt% to 2.0wt%, for example 0.5wt%, 1.0wt%, 1.5wt% or 2.0wt%.

[0019] The present invention also provides the application of the above-mentioned titanium-silicon molecular sieve aggregate sound-absorbing material in the field of acoustics.

[0020] Furthermore, the sound-absorbing material is used to prepare sound-absorbing materials in acoustic elements or loudspeaker devices, and effectively improves their acoustic performance by filling the rear cavity.

[0021] Furthermore, the sound-absorbing material is used to prepare a sound-absorbing material that fills the rear cavity of a loudspeaker.

[0022] Compared with the prior art, the present invention has the following beneficial effects: (1) Unique structural and performance advantages: The present invention obtains a titanium-silicon molecular sieve with a special multi-level morphology of 200-1200 nm aggregates composed of basic particles through controlled synthesis, with a silicon-to-titanium ratio of 25-100; the structure combines high bulk density (0.52-0.70 g / cm³) with high specific surface area and abundant mesopores; high bulk density provides high vibrational mass, while the pores between nano-basic particles optimize gas diffusion, and the two work together to maximize acoustic performance.

[0023] (2) Significant acoustic enhancement effect: When applied to loudspeaker sound-absorbing materials, the titanium silicon molecular sieve agglomerates of the present invention can generate a larger ΔF0 (reduction value of resonant frequency) under the same filling volume due to their high bulk density and optimized pores. The low frequency enhancement effect is significantly better than that of traditional high silicon ZSM-5 molecular sieve and traditional titanium silicon molecular sieve.

[0024] (3) Good hydrophobicity and anti-aging properties: The appropriate silicon-titanium molar ratio endows the material with intrinsic hydrophobicity (static water adsorption ≤1.5%), effectively resisting the erosion of performance by humidity, ensuring the stability of acoustic performance in long-term use or harsh environment, meeting the high reliability requirements of consumer electronics products, and is particularly suitable for acoustic enhancement of miniaturized electronic devices. Attached Figure Description

[0025] Figure 1 The images are SEM images of the samples obtained in Examples 1-4 and Comparative Example 2.

[0026] Figure 2 The images are SEM images of the samples obtained in Examples 5-9 and Comparative Examples 3-4.

[0027] Figure 3 The images are SEM images of the samples obtained in Examples 10-12 and Comparative Examples 7 and 9.

[0028] Figure 4 The image shows the SEM image of the sample obtained in Comparative Example 10. Detailed Implementation

[0029] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. These embodiments are based on the technical solution of the present invention and provide detailed implementation methods and specific operating procedures. However, the scope of protection of the present invention is not limited to the following embodiments.

[0030] Specifically, the template agent in the embodiments of this invention application is a commercially available 25% tetrapropylammonium hydroxide aqueous solution, with the remainder being water; tetraethyl orthosilicate is a commercially available reagent containing ≥28.4% SiO2; tetrabutyl titanate is a commercially available reagent with a purity ≥95.8%; and Tween-20, Tween-40, and Tween-60 are commercially available reagents.

[0031] Special note: The basic particles (primary particles) that make up the aggregates in this invention refer to the aggregates of this invention that are observed by scanning electron microscopy (SEM) to be composed of multiple small particles. The small particles are the basic particles mentioned above. The size of the aggregates is obtained by statistical analysis of the SEM images.

[0032] Examples 1-12 and Comparative Examples 1-9 Preparation and characterization of titanium-silicon molecular sieve sound-absorbing materials In each embodiment and comparative example, following the molar ratios shown in Table 1, tetraethyl orthosilicate (TEOS) and tetrabutyl titanate (TBOT) were added dropwise to a tetrapropylammonium hydroxide (TPAOH) aqueous solution under stirring. A surfactant was added, and stirring continued to form a homogeneous gel. The gel was then transferred to a polytetrafluoroethylene-lined high-pressure reactor and statically crystallized at the temperatures specified in Table 1 for a certain time. The size and agglomeration degree of the basic particles were controlled by adjusting the crystallization temperature and time. After crystallization, the product was centrifuged, repeatedly washed with deionized water until neutral, dried at 90-120°C for 6-12 hours, and then calcined in a muffle furnace at 500-650°C for 2-8 hours to completely remove the organic template agent, yielding titanium-silicon molecular sieve sound-absorbing material samples. Except for the preparation conditions shown in Table 1, all other operations in each embodiment and comparative example were the same.

[0033] The structural type of the samples was tested using X-ray diffraction, and the Si / Ti molar ratio was determined using X-ray fluorescence spectroscopy (XRF). The morphology was observed using scanning electron microscopy (SEM), and the size of at least 30 randomly selected aggregate particles was statistically measured, and the average size of the aggregates was calculated. Similarly, the size of the constituent units (basic particles) of at least 30 of the above aggregates was measured, and the average size of the basic particles was calculated. The bulk density was measured according to GB / T 16913-2008. The static water adsorption capacity was determined according to GB / T 6287-2021. The specific results are shown in Table 1, and the morphology images of the molecular sieves prepared in each example and comparative example are shown in [Table 1]. Figures 1-4 .

[0034] Table 1. Preparation parameters and basic structural properties of titanium-silicon molecular sieves in each example and comparative example. As shown in Table 1, the experimental data demonstrate that introducing surfactants into the TS-1 synthesis system yields TS-1 molecular sieves with MFI crystal phase exhibiting agglomerate morphology within a silicon-to-titanium ratio range of 1:(0.01-0.04). However, in Comparative Example 1, a high-crystallinity TS-1 molecular sieve cannot be obtained due to excessive titanium introduction. In Comparative Example 2, the extremely low titanium content results in a product with MFI structure, which can be considered pure silicon molecular sieve Silicalite-1. SEM characterization shows that its crystals are not formed by the aggregation of basic particles but exist as small-grain-scale blocks, thus not agglomerates. Table 1 also shows that introducing Tween-20, Tween-40, and Tween-60 into the TS-1 synthesis system also yields TS-1 molecular sieves with MFI crystal phase exhibiting agglomerate morphology. Furthermore, as shown in Table 1, Examples 2, 7-9, when the mass ratio of Tween-40 to silica in tetraethyl orthosilicate is between 0.5% and 5%, TS-1 molecular sieves with an aggregated MFI crystalline phase can be obtained. Without the introduction of a surfactant (Comparative Example 3, i.e., a traditional titanium-silicon molecular sieve), or with an excessively small amount (Comparative Example 4, only 0.2%), blocky TS-1 molecular sieves, rather than aggregates, are obtained. Excessive introduction of Tween (Comparative Example 5) slows down the crystallization of TS-1 molecular sieves, resulting in excessively low crystallinity of the product. Therefore, the introduction of Tween surfactant is essential for obtaining TS-1 molecular sieves with an aggregated MFI crystalline phase, and its amount needs to be controlled within 0.5%-5% of the mass of silica in tetraethyl orthosilicate.

[0035] Crystallizing the above-mentioned synthetic slurry at 150-180°C for 24-48 hours yielded TS-1 molecular sieves with MFI crystalline phase exhibiting agglomerate morphology (Examples 10-12). Short crystallization times or temperatures below 150°C failed to produce highly crystalline products (Comparative Examples 6, 8); excessively high temperatures or prolonged crystallization times caused the agglomerates to grow into large crystal grains (Comparative Examples 7, 9).

[0036] All products with agglomerated morphology obtained in Examples 1-12 above are composed of agglomerated basic particles of 10-150 nm, with agglomerate sizes between 200-1200 nm. The titanium-silicon molecular sieve agglomerates prepared in the above examples contain both the inherent 0.5-0.6 nm micropores of the TS-1 molecular sieve and interparticle mesopores of 2-10 nm formed by the accumulation of basic particles, with a bulk density between 0.52-0.70 g / cm³. 3 Between, and the water absorption rate is ≤1.5%.

[0037] Comparative Example 10 High-silica ZSM-5 molecular sieve ZSM-5 molecular sieves with a silicon-to-aluminum molar ratio (SAR) of approximately 1000 were synthesized using a conventional hydrothermal method (silicon source: silica sol; template agent: TPAOH). The morphology of this high-silicon ZSM-5 molecular sieve consisted primarily of relatively regular crystals with an average particle size of 527 nm and a bulk density of 0.37 g / cm³. 3 The static water adsorption capacity is 1.3%.

[0038] Example 13 Application performance verification experiment: sound absorption test The titanium-silicon molecular sieve sound-absorbing material samples prepared in the above embodiments and comparative examples were granulated to 150-200 mesh, and then 0.12 g was accurately weighed and filled into a standard miniature loudspeaker test module. The cavity resonant frequency (F0 empty) and the resonant frequency after filling (F0 filled) were measured and recorded using a precision impedance analyzer. The change in de-harmonic frequency ΔF0 was calculated as: ΔF0 = F0 empty - F0 filled.

[0039] Reliability (anti-aging) test: The above molecular sieve samples were placed in an environmental test chamber at 85℃ and 85% relative humidity for 72 hours. The resonant frequency (F0 aging) of the sample after aging was measured again, and ΔF0 aging was calculated. ΔF0 aging = F0 empty - F0 aging.

[0040] The test results are recorded in Table 2.

[0041] Table 2. Acoustic performance test results of sound-absorbing materials In Table 2, the ΔF0 improvement rate = [(Example ΔF0 - Comparative Example 10 ΔF0) / Comparative Example 10 ΔF0] × 100%, is based on the Comparative Example 10 sample.

[0042] As shown in Table 2, the sound-absorbing material prepared using the titanium-silicon molecular sieve of this invention exhibits significantly better harmonic reduction performance (ΔF0) than the traditional high-silicon ZSM-5 material (Comparative Example 10), with an improvement of over 138%. Combining the data from Tables 1 and 2, it can be seen that the formation of titanium-silicon molecular sieve agglomerates has a significant impact on the acoustic performance of the sound-absorbing material. Compared to the non-agglomerated titanium-silicon molecular sieve synthesized without Tween in Comparative Example 3, the ΔF0 of the titanium-silicon molecular sieve agglomerate sound-absorbing material prepared by this invention is significantly improved. This is directly attributed to the high bulk density and unique nano-agglomerate structure of the titanium-silicon molecular sieve of this invention; the former provides greater inertial mass, while the latter optimizes gas throughput. Furthermore, after high-temperature and high-humidity aging, the sound-absorbing material of this invention maintains a higher performance retention rate (less ΔF0 decreases with aging), verifying its excellent hydrophobic stability and anti-aging performance, fully meeting the material performance requirements for acoustic applications protected by the claims.

[0043] The above description is only a preferred embodiment of the present invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A titanium-silicon molecular sieve aggregate sound-absorbing material, characterized in that, The molar ratio of silicon to titanium in the skeleton of the sound-absorbing material is 25:1 to 100:

1. The morphology of the sound-absorbing material is an aggregate composed of basic particles, the size of which is 200-1200 nm. The bulk density of the sound-absorbing material is 0.52 g / cm³. 3 ~0.70 g / cm 3 .

2. The titanium-silicon molecular sieve agglomerate sound-absorbing material according to claim 1, characterized in that, The molar ratio of silicon to titanium is 25:1 to 60:

1.

3. The titanium-silicon molecular sieve agglomerate sound-absorbing material according to claim 1, characterized in that, The size of the elementary particles is 10-150 nm.

4. The titanium-silicon molecular sieve agglomerate sound-absorbing material according to claim 1, characterized in that, The sound-absorbing material has an MFI structure.

5. The titanium-silicon molecular sieve agglomerate sound-absorbing material according to claim 1, characterized in that, The sound-absorbing material has a multi-level pore structure with both micropores and mesopores, wherein the micropore diameter ranges from 0.5 to 0.6 nm and the mesopore diameter ranges from 2 to 10 nm.

6. The titanium-silicon molecular sieve agglomerate sound-absorbing material according to claim 1, characterized in that, The static adsorption capacity of the sound-absorbing material for water is ≤1.5%.

7. A method for preparing the titanium-silicon molecular sieve agglomerate sound-absorbing material according to any one of claims 1-6, characterized in that, Includes the following steps: Silicon source, titanium source, template agent, surfactant and water are mixed evenly to form an initial gel mixture; then hydrothermal crystallization reaction is carried out at 150-180℃ for 24-48 hours; after the reaction, the product is subjected to solid-liquid separation, washing, drying and calcination to obtain the desired titanium silicon molecular sieve agglomerate sound-absorbing material.

8. The preparation method according to claim 7, characterized in that, The silicon source is selected from tetraethyl orthosilicate, the titanium source is selected from tetrabutyl titanate, the template agent is selected from tetrapropylammonium hydroxide, and the surfactant is selected from at least one of Tween-20, Tween-40, or Tween-60.

9. The preparation method according to claim 8, characterized in that, The amount of surfactant added is 0.5wt% to 5.0wt% of the mass of SiO2 in the silicon source.

10. The application of the titanium-silicon molecular sieve agglomerate sound-absorbing material according to any one of claims 1-6 or the titanium-silicon molecular sieve agglomerate sound-absorbing material prepared by the preparation method according to any one of claims 7-9, characterized in that, Sound-absorbing materials used in the manufacture of acoustic components or loudspeaker devices.

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