WO2023279513A1

WO2023279513A1 - Zsm-5 molecular sieve for sound-absorbing material, preparation method therefor, and resulting product

Info

Publication number: WO2023279513A1
Application number: PCT/CN2021/117060
Authority: WO
Inventors: 宋锡滨; 张曦; 张兵
Original assignee: 山东国瓷功能材料股份有限公司
Priority date: 2021-07-05
Filing date: 2021-09-08
Publication date: 2023-01-12
Also published as: TW202302458A; CN113184876B; TWI788013B; CN113184876A

Abstract

A ZSM-5 molecular sieve provided by the present application has a silicon-to-aluminum mass ratio of 800-4000, a specific surface area of micropores less than 72 m2/g, a pore size range of the micropores between 0.5 nm and 1.5 nm, a pore size range of mesopores between 2 nm and 10 nm, and a ratio of the cumulative pore volume of the micropores to the cumulative pore volume of the mesopores being 0.24-0.35. According to the present application, by controlling the range of the silicon-to-aluminum ratio for synthesizing the molecular sieve, parameters of the sound-absorbing material such as the hydrophobic performance, the ratio of the pore volume of micropores to the pore volume of mesopores, and the specific surface area are controlled within a better range; thus, the sound-absorbing material has an optimal resonance frequency reduction function when applied in a loudspeaker device, and has optimal anti-aging performance, thereby meeting application requirements for the loudspeaker; the present application has a broad application prospect.

Description

ZSM-5 molecular sieve used for sound-absorbing material, its preparation method and obtained product

This application claims the priority of the Chinese patent application submitted to the China Patent Office on July 05, 2021, with the application number 202110754518.4 and the application name "ZSM-5 molecular sieve for sound-absorbing materials, its preparation method and the resulting product". The entire contents are incorporated by reference in this application.

technical field

The application belongs to the technical field of molecular sieves, and in particular relates to a ZSM-5 molecular sieve used for sound-absorbing materials, its preparation method and the obtained product.

Background technique

With the development of the Internet and the intelligent acoustic industry, people yearn for a colorful life, and their pursuit of perfect sound quality is getting higher and higher. As the most important part of the speaker, the speaker is closely related to the sound quality of the speaker. According to relevant research, the size of the cavity of the speaker plays a vital role in its sound quality. The larger the cavity, the easier it is to improve the sound quality. However, mobile electronic products are gradually developing towards portability and miniaturization, and speakers are also evolving towards miniaturization. The cavity space becomes smaller, and the resonant frequency of the sound-generating device becomes higher, which leads to the deterioration of the low-frequency performance of the speaker, thereby affecting the sound quality of the sound.

In order to improve the low-frequency effect of the micro-speaker, a common solution is to add porous materials to the speaker to reduce the F0 (resonant frequency) of the sound generator, so as to achieve the purpose of optimizing the sound effect. Porous materials include activated carbon, zeolite molecular sieves, silica, alumina, carbon nanotubes, etc. The porous material can increase the virtual volume of the rear cavity, which helps to improve the acoustic performance of the mid-low frequency. Zeolite molecular sieves have been used more and more in recent years due to their unique structures such as regular multi-dimensional channels, such as in Chinese invention patent applications CN108566593A and CN111586550A.

Zeolite molecular sieves have well-developed pore structures, such as micropores and mesopores, which determine the adsorption performance of the adsorption material. Micropores are used to store gas, and mesopores are channels for gas transmission. According to literature reports, the ratio of silicon to aluminum of molecular sieves is different, the size and number of micropores and mesopores are different, the hydrophobic properties are different, and the adsorption properties for VOCs (Volatile Organic Compounds) are also different. Therefore, how to provide a new ZSM-5 (Zeolite Socony Mobil-5) molecular sieve material, to avoid the failure of the molecular sieve, and to improve the sound-absorbing effect of the sound-generating device will be an urgent research topic in this area.

Contents of the invention

Aiming at the above problems, the present application provides a ZSM-5 molecular sieve for sound-absorbing materials, its preparation method and the resulting product, the specific scheme is as follows.

A ZSM-5 molecular sieve used for sound-absorbing materials, the ZSM-5 molecular sieve has a silicon-aluminum mass ratio of 800-4000, a micropore specific surface area of <72m ² /g, and a micropore diameter range of 0.5-1.5nm , the mesopore diameter ranges between 2-10nm, and the ratio of the cumulative pore volume of the micropores to the cumulative pore volume of the mesopores is 0.24-0.35.

In some embodiments, the micropore volume of the ZSM-5 molecular sieve is 0.043-0.050ml/g, and the mesopore volume is 0.16-0.21ml/g.

In some embodiments, the water adsorption capacity of the ZSM-5 molecular sieve is ≤1.25%. After it is filled in the rear cavity of the speaker and absorbs water, the change ΔF0 of its resonance frequency is still greater than 60 Hz.

The present application also provides a method for preparing a ZSM-5 molecular sieve for sound-absorbing materials according to any one of the above technical solutions, comprising the following steps:

Mix alkali source, aluminum source, template agent, silicon source, ZSM-5 molecular sieve seed with water to form a gel;

The obtained gel is placed in a reaction kettle, and a hydrothermal crystallization reaction is carried out under autogenous pressure. After the reaction is completed, solid-liquid separation, washing, drying, and roasting are carried out in sequence to obtain the molecular sieve powder;

The obtained molecular sieve raw powder is ion-exchanged with ammonium salt solution, filtered and separated to obtain a solid product, and the obtained solid product is repeatedly washed with deionized water until neutral, and the filter cake is dried and roasted by segmental microwaves to obtain ZSM-5 molecular sieve.

In some embodiments, the molar ratio of added water, alkali source, aluminum source, templating agent, and silicon source is (2-10): (0.03-0.20): (0.00025-0.0033): (0.03-0.50): 1, where silicon source is calculated as silicon source oxide.

In some embodiments, based on the mass of silicon source oxide, the mass of ZSM-5 seed crystals added is 3-8 wt%.

In some embodiments, the ammonium salt solution is selected from at least one of ammonium chloride, ammonium nitrate, and ammonium sulfate, with a concentration of 0.1-2mol/L and a solid-to-liquid ratio of 1:(1-10).

In some embodiments, the silicon source is selected from at least one of solid silica gel, silica sol, sodium silicate nonahydrate, silicon powder, white carbon black, diatomaceous earth, silicate, and tetraethyl orthosilicate;

The alkali source is an alkali metal hydroxide;

The templating agent is selected from diethylamine, tetraethylammonium bromide, tetraethylammonium chloride, tetraethylammonium hydroxide, tetrapropylammonium chloride, tetrapropylammonium bromide, tetrapropylammonium hydroxide, At least one of 1,6-hexanediamine;

The aluminum source is selected from at least one of aluminum hydroxide, pseudoboehmite, aluminum sulfate, sodium metaaluminate, aluminum isopropoxide, aluminum nitrate, aluminum oxide, and aluminum chloride.

In some embodiments, the silicon source is selected from at least one of solid silica gel, silica sol, silica powder and tetraethyl orthosilicate;

The templating agent is selected from at least one of tetraethyl bromide/ammonium chloride, tetraethyl ammonium hydroxide, tetrapropyl bromide/ammonium chloride, tetrapropyl ammonium hydroxide;

The aluminum source is selected from at least one of aluminum sulfate, sodium metaaluminate, and aluminum hydroxide;

The alkali source is at least one selected from sodium hydroxide and potassium hydroxide.

In some embodiments, in order to optimize the degree of damage to product channels during the drying process, in the step of obtaining ZSM-5 molecular sieves, the segmental microwave drying is specifically carried out in two stages, wherein the microwave drying temperature of the first stage is 10- 20°C, the time is 0.5-3h; the second stage microwave drying temperature is 20-30°C, the time is 0.5-3h; the roasting temperature is 550-600°C.

In some embodiments, in the step of obtaining the raw molecular sieve powder, the hydrothermal crystallization temperature is 150-200°C, the crystallization time is 20-48h; the drying temperature is 10-30°C, and the calcination temperature is 550-600°C.

The present application also provides a sound-absorbing material prepared by using the ZSM-5 molecular sieve described in any one of the above technical solutions.

In some embodiments, the ZSM-5 molecular sieve is presented in at least one form of powder, granule, block, molecular sieve membrane, or packaging with powder/granule/block as content.

The present application provides an acoustic component, which is prepared by using the sound-absorbing material described in any one of the above-mentioned technical solutions.

The present application provides a loudspeaker device, which is prepared by using the sound-absorbing material described in any one of the above-mentioned technical solutions.

Compared with the prior art, the advantages and positive effects of the present application are:

This application provides a ZSM-5 molecular sieve for sound-absorbing materials, which controls the range of the silicon-aluminum ratio synthesized by the molecular sieve, and adjusts the parameters such as the hydrophobicity of the sound-absorbing material, the ratio of the micropore volume to the mesopore volume, and the specific surface area. It is controlled within a better range, so that the sound-absorbing material used in the speaker device has the best detuning frequency, and has the best anti-aging performance.

The sound-absorbing material prepared based on molecular sieve samples provided by this application has good hydrophobicity, relatively suitable pore structure and specific surface area, which is conducive to the adsorption and desorption of air molecules, and can better meet the application requirements of loudspeakers. application prospects.

Description of drawings

FIG. 1 is an XRD pattern according to Examples 1-4 and Comparative Example 1 and Comparative Example 4 of the present application.

detailed description

The following will clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in this application, all other embodiments obtained by persons of ordinary skill in the art without making creative efforts belong to the scope of protection of this application.

It should be understood that although the specific order of method steps may be shown in the embodiment, this does not require or imply that these operations must be performed in this specific order, unless otherwise specified or the relationship between the steps determines the execution order . Such variants will depend on choice. Additionally or alternatively, certain steps may be omitted, multiple steps may be combined into one step for execution, and/or one step may be decomposed into multiple steps for execution. All such variations are within the scope of this disclosure.

In the description of this application, it should be noted that, unless otherwise specified and limited, the term "silicon-aluminum ratio" refers to the "silicon-aluminum molar ratio", specifically the molar ratio of SiO ₂ and Al ₂ O ₃ , Expressed in SAR.

Example 1

Silicon source (30% silica sol), alkali source (NaOH), aluminum source (sodium metaaluminate), template (tetrapropylammonium bromide), according to 200SiO ₂ :0.25Al ₂ O ₃ :25NaOH:10TPABr : 3000H ₂ O ratio mixed to prepare a gel, add commercially available ZSM-5 seed crystal 3wt% (by SiO ₂ mass). Place it in a crystallization kettle, crystallize at 160°C for 48 hours, and then water-cool and wash after the crystallization is complete. After microwave drying at 10°C and 25°C for 1.5h and 0.5h respectively, ZSM-5 molecular sieves were obtained by calcination and exchange. The specific parameters of this embodiment are shown in Table 1.

Example 2

Silicon source (30% silica sol), alkali source (NaOH), aluminum source (sodium metaaluminate), template (tetrapropylammonium bromide), according to 200SiO ₂ :0.20Al ₂ O ₃ :25NaOH:10TPABr : 3000H ₂ O ratio mixed to prepare a gel, add commercially available ZSM-5 seed crystal 5wt% (by SiO ₂ mass). Place it in a crystallization kettle, crystallize at 150°C for 48 hours, and then water-cool and wash after the crystallization is complete. After microwave drying at 10°C and 25°C for 1.5h and 0.5h respectively, ZSM-5 molecular sieves were obtained by exchange after calcination. The specific parameters of this embodiment are shown in Table 1.

Example 3

Silicon source (30% silica sol), alkali source (NaOH), aluminum source (sodium metaaluminate), template (tetrapropylammonium bromide), according to 200SiO ₂ :0.13Al ₂ O ₃ :25NaOH:10TPABr: The ratio of 3000H ₂ O was mixed to prepare a gel, and 8 wt% of commercially available ZSM-5 seeds (calculated by SiO ₂ mass) were added. Place it in a crystallization kettle, crystallize at 160°C for 36 hours, cool with water after crystallization, and wash. After microwave drying at 10°C and 25°C for 1.5h and 0.5h respectively, ZSM-5 molecular sieves were obtained by exchange after calcination. The specific parameters of this embodiment are shown in Table 1.

Example 4

Silicon source (30% silica sol), alkali source (NaOH), aluminum source (sodium metaaluminate), template (tetrapropylammonium bromide), according to 200SiO ₂ :0.10Al ₂ O ₃ :25NaOH:10TPABr: The ratio of 3000H ₂ O was mixed to prepare a gel, and 3wt% of commercially available ZSM-5 seed crystals (calculated as SiO ₂ mass) were added. Place it in a crystallization kettle, crystallize at 160°C for 40 hours, and then water-cool and wash after the crystallization is complete. After microwave drying at 10°C and 25°C for 1.5h and 0.5h respectively, ZSM-5 molecular sieves were obtained by exchange after calcination. The specific parameters of this embodiment are shown in Table 1.

Example 5

Silicon source (30% silica sol), alkali source (NaOH), aluminum source (sodium metaaluminate), template (tetrapropylammonium bromide), according to 200SiO ₂ :0.08Al ₂ O ₃ :25NaOH:10TPABr: The ratio of 3000H ₂ O was mixed to prepare a gel, and 3wt% of commercially available ZSM-5 seed crystals (calculated as SiO ₂ mass) were added. Place it in a crystallization tank, crystallize at 170°C for 20 hours, and then water-cool and wash after the crystallization is complete. After microwave drying at 10°C and 25°C for 1.5h and 0.5h respectively, ZSM-5 molecular sieves were obtained by exchange after calcination. The specific parameters of this embodiment are shown in Table 1.

Example 6

Silicon source (30% silica sol), alkali source (NaOH), aluminum source (sodium metaaluminate), template (tetrapropylammonium bromide), according to 200SiO ₂ :0.067Al ₂ O ₃ :25NaOH:10TPABr: The ratio of 3000H ₂ O was mixed to prepare a gel, and 3wt% of commercially available ZSM-5 seed crystals (calculated as SiO ₂ mass) were added. Place it in a crystallization kettle, crystallize at 180°C for 24 hours, cool with water after crystallization, and wash. After microwave drying at 10°C and 25°C for 1.5h and 0.5h respectively, ZSM-5 molecular sieves were obtained by exchange after calcination. The specific parameters of this embodiment are shown in Table 1.

Example 7

Silicon source (30% silica sol), alkali source (NaOH), aluminum source (sodium metaaluminate), template (tetrapropylammonium bromide), according to 200SiO ₂ :0.057Al ₂ O ₃ :25NaOH:10TPABr: The ratio of 3000H ₂ O was mixed to prepare a gel, and 3wt% of commercially available ZSM-5 seed crystals (calculated as SiO ₂ mass) were added. Place it in a crystallization kettle, crystallize at 150°C for 48 hours, and then water-cool and wash after the crystallization is complete. After microwave drying at 10°C and 25°C for 1.5h and 0.5h respectively, ZSM-5 molecular sieves were obtained by exchange after calcination. The specific parameters of this embodiment are shown in Table 1.

Example 8

Silicon source (30% silica sol), alkali source (NaOH), aluminum source (sodium metaaluminate), template (tetrapropylammonium bromide), according to 200SiO ₂ :0.05Al ₂ O ₃ :25NaOH:10TPABr: The ratio of 3000H ₂ O was mixed to prepare a gel, and 3wt% of commercially available ZSM-5 seed crystals (calculated as SiO ₂ mass) were added. Put it in a crystallization kettle, crystallize at 170°C for 30h, and then water-cool and wash after the crystallization is complete. After microwave drying at 10°C and 25°C for 1.5h and 0.5h respectively, ZSM-5 molecular sieves were obtained by exchange after calcination. The specific parameters of this embodiment are shown in Table 1.

Comparative example 1

Silicon source (30% silica sol), alkali source (NaOH), aluminum source (sodium metaaluminate), template (tetraethylammonium bromide), according to 200SiO ₂ :0.66Al ₂ O ₃ :25NaOH:12TPABr : 3000H ₂ O ratio mixed to prepare a gel, add commercially available ZSM-5 seed crystal 5wt% (by SiO ₂ mass). Place it in a crystallization kettle, crystallize at 160°C for 48 hours, cool with water after crystallization, wash, dry, and roast to obtain ZSM-5 molecular sieves by exchange. The specific parameters of this comparative example are shown in Table 1.

Comparative example 2

Silicon source (30% silica sol), alkali source (NaOH), aluminum source (sodium metaaluminate), template (tetrapropylammonium bromide), according to 200SiO ₂ :0.33Al ₂ O ₃ :25NaOH:12TPABr : 3000H ₂ O ratio mixed to prepare a gel, add commercially available ZSM-5 seed crystal 3wt% (by SiO ₂ mass). Place it in a crystallization kettle, crystallize at 160°C for 48 hours, cool with water after crystallization, wash, dry, and roast to obtain ZSM-5 molecular sieves by exchange. The specific parameters of this comparative example are shown in Table 1.

Comparative example 3

Silicon source (30% silica sol), alkali source (NaOH), aluminum source (sodium metaaluminate), template (tetrapropylammonium bromide), according to 200SiO ₂ :0.033Al ₂ O ₃ :25NaOH:12TPABr : 3000H ₂ O ratio mixed to prepare a gel, add commercially available ZSM-5 seed crystal 8wt% (by SiO ₂ mass). Place it in a crystallization kettle, crystallize at 160°C for 48 hours, cool with water after crystallization, wash, dry, and roast to obtain ZSM-5 molecular sieves by exchange. The specific parameters of this comparative example are shown in Table 1.

Comparative example 4

Silicon source (30% silica sol), alkali source (NaOH), aluminum source (sodium metaaluminate), template (tetrapropylammonium bromide), according to 200SiO ₂ :0.025Al ₂ O ₃ :25NaOH:10TPABr: The ratio of 3000H ₂ O was mixed to prepare a gel, and 3wt% of commercially available ZSM-5 seed crystals (calculated as SiO ₂ mass) were added. Place it in a crystallization kettle, crystallize at 160°C for 48 hours, cool with water after crystallization, wash, dry, and roast to obtain ZSM-5 molecular sieves by exchange. The specific parameters of this comparative example are shown in Table 1.

Comparative example 5

Silicon source (30% silica sol), alkali source (NaOH), aluminum source (sodium metaaluminate), template (tetraethylammonium bromide), according to 200SiO ₂ :0.20Al ₂ O ₃ :25NaOH:10TPABr : 3000H ₂ O ratio mixed to prepare a gel, add commercially available ZSM-5 seed crystal 3wt% (by SiO ₂ mass). Place it in a crystallization kettle, crystallize at 160°C for 48 hours, cool with water after crystallization, wash, dry, and roast to obtain ZSM-5 molecular sieves by exchange. The specific parameters of this comparative example are shown in Table 1.

Comparative example 6

Silicon source (30% silica sol), alkali source (NaOH), aluminum source (sodium metaaluminate), template (tetraethylammonium bromide), according to 200SiO ₂ :0.10Al ₂ O ₃ :25NaOH:10TPABr : 3000H ₂ O ratio mixed to prepare a gel, add commercially available ZSM-5 seed crystal 5% (by SiO ₂ mass). Place it in a crystallization kettle, crystallize at 160°C for 48 hours, cool with water after crystallization, wash, dry, and roast to obtain ZSM-5 molecular sieves by exchange. The specific parameters of this comparative example are shown in Table 1.

Comparative example 7

Silicon source (30% silica sol), alkali source (NaOH), aluminum source (sodium metaaluminate), template (n-butylamine), according to 200SiO ₂ :0.20Al ₂ O ₃ :25NaOH:40BA:3000H ₂ The ratio of O was mixed to prepare a gel, and 3 wt% (by weight of SiO ₂ ) was added to commercially available ZSM-5 seed crystals. Place it in a crystallization kettle, crystallize at 160°C for 48 hours, cool with water after crystallization, wash, dry, and roast to obtain ZSM-5 molecular sieves by exchange. The specific parameters of this comparative example are shown in Table 1.

Comparative example 8

Silicon source (30% silica sol), alkali source (NaOH), aluminum source (sodium metaaluminate), template (n-butylamine), according to 200SiO ₂ :0.10Al ₂ O ₃ :25NaOH:40BA:3000H ₂ The ratio of O was mixed to prepare a gel, and 5 wt% of commercially available ZSM-5 seed crystals (based on SiO ₂ mass) were added. Place it in a crystallization kettle, crystallize at 160°C for 48 hours, cool with water after crystallization, wash, dry, and roast to obtain ZSM-5 molecular sieves by exchange. The specific parameters of this comparative example are shown in Table 1.

Comparative example 9

Silicon source (30% silica sol), alkali source (NaOH), aluminum source (sodium metaaluminate), template (n-butylamine), according to 200SiO ₂ :0.10Al ₂ O ₃ :25NaOH:40BA:2000H ₂ The ratio of O was mixed to prepare a gel, and 5 wt% of commercially available ZSM-5 seed crystals (based on SiO ₂ mass) were added. Put it in a crystallization kettle, crystallize at 160°C for 48 hours, cool with water after crystallization, wash, dry, roast and exchange to obtain ZSM-5 molecular sieve. The specific parameters of this comparative example are shown in Table 1.

Comparative example 10

Silicon source (30% silica sol), alkali source (NaOH), aluminum source (sodium metaaluminate), template (n-butylamine), according to 200SiO ₂ :0.10Al ₂ O ₃ :25NaOH:50BA:3000H ₂ The ratio of O was mixed to prepare a gel, and 5 wt% of commercially available ZSM-5 seed crystals (based on SiO ₂ mass) were added. Place it in a crystallization kettle, crystallize at 160°C for 48 hours, cool with water after crystallization, wash, dry, and roast to obtain ZSM-5 molecular sieves by exchange. The specific parameters of this comparative example are shown in Table 1.

Performance Testing

The relevant parameter test methods are as follows:

The pore structure data of molecular sieves were determined by Micrometics ASAP 2420 static nitrogen adsorption instrument.

Measurement conditions: place the sample in the sample processing system, vacuumize to 1.33×10 ^-2 Pa at 350°C, hold the temperature and pressure for 15 hours, and purify the sample;

At liquid nitrogen -196°C, measure the nitrogen adsorption and desorption of the purified sample under different specific pressure p/p0 conditions, and obtain the nitrogen adsorption-desorption isotherm;

Calculate the BET total specific surface (S _BET ) using the BET formula (the specific value is not shown, and serve in the calculation process of the micropore specific surface area), and use the t-plot method to calculate the micropore specific surface area (Smicro) and micropore volume of the sample (Vmicro), the mesopore volume (Vmeso) of the sample was calculated by the BJH method.

Test the effect of a molecular sieve on the ratio of silicon to aluminum

1. Influence on the adsorption performance of water and VOCs components

The change of the silicon-aluminum ratio of the molecular sieve affects its adsorption performance to water and VOCs components, so the molecular sieve samples in Examples 1-8 and Comparative Examples 1-10 were tested respectively with reference to the national standard GB6287-1986 "Molecular Sieve Static Water Adsorption Determination Method" At the same time, several common organic compounds were selected as VOCs gas for testing. The experimental results are shown in Table 1.

Table 1 Pore structure parameters and static water and VOCs adsorption capacity of zeolite molecular sieves

It can be seen from the data in Table 1 that:

(1) When the silicon-aluminum ratio of the molecular sieve was less than 800 (comparative example 1 and comparative example 2), the adsorption capacity of water was higher than 3.0%; the ratio of micropore volume to mesopore volume was higher than 0.40, and the micropore specific surface area Higher than 120m ² /g, the pore diameter range is 0.8-2.0nm;

(2) When the silicon-aluminum ratio of the molecular sieve is greater than 4000 (comparative example 3 and comparative example 4), the adsorption capacity of the VOCs component (toluene) is higher than 12%, and the ratio of the micropore volume to the mesopore volume is lower than 0.24 , the micropore specific surface area is higher than 90m ² /g, and the mesopore diameter range is 2.0-20nm;

(3) When the silicon-aluminum ratio of the molecular sieve is between 800-4000, the change of the silicon-aluminum ratio, the adsorption capacity of water and VOCs components changes little, the adsorption capacity of water is lower than 1.25%, the VOCs component (toluene) The adsorption capacity is less than 12%, which is more suitable for making sound-absorbing materials.

2. Influence on aging resistance

The samples of Examples 1-8, Comparative Examples 1 and 2, Comparative Examples 3 and 4 were filled in the rear cavity of the speaker system, and the aging resistance of the samples was investigated. The results are shown in Table 2.

Determination method of aging resistance performance: put the molecular sieve sample, water or VOCs components together in the reagent bottle, and close the lid. Put the reagent bottle in an oven at 85°C for 2-4 hours, take it out and cool it to room temperature, and measure the change of resonance frequency ΔF0 before and after putting it in. Among them, the smaller ΔF0 represents the easier attenuation and the worse the aging resistance. Generally, when ΔF0 is between 0-30, the aging resistance of the sample is the weakest, between 30-60, the aging resistance is weak, and between 60-∞, the aging resistance is good.

Table 2 Changes in ΔF0 after adding samples in the speaker cavity

It can be seen from the data in Table 2 that the samples of Examples 1-8 and Comparative Examples 1-4 are filled in the rear cavity of the loudspeaker, and both can reduce F0, and the difference is not obvious. However, after the sample absorbs water or VOCs components, and then test F0, it will be found that the molecular sieve samples (800<SAR<4000) of Examples 1-8 of the present application can still effectively reduce F0, while other samples of Comparative Examples 1-4 Molecular sieves (SAR>4000, SAR<800) did not significantly reduce F0.

Among them, the samples with SAR<800 have the smallest decrease in F0, below 30, the anti-aging performance of the sample is the weakest; the samples with SAR>4000 have a small decrease in F0, between 30-60, the anti-aging performance of the sample is the weakest. The performance is relatively weak; while the samples of the present application have a reduction value of F0 greater than 60, indicating that the samples have better anti-aging properties.

3. Effect on crystal structure

Figure 1 is the XRD spectrum according to Examples 1-4 of the present application and Comparative Example 1 and Comparative Example 4; wherein: the abscissa represents the 2θ angle range scanned by the XRD diffractometer, and the ordinate represents the intensity of the diffraction peak.

Among the figure, A-D represents the molecular sieve sample (silicon-aluminum ratio 800-2000) that the application embodiment 1-4 provides, E represents the sample of comparative example 1 (silicon-aluminum ratio 300), and F represents comparative example 4 (silicon-aluminum ratio 8000) )sample. It can be seen from the figure that the change of the silicon-aluminum ratio of the molecular sieve will not affect the crystal structure of the sample.

Test the influence of the cumulative pore volume of micropores and the cumulative pore volume ratio of mesopores

Molecular sieves have a micropore and mesoporous channel structure. The micropores are mainly used to absorb and accommodate air molecules, while the mesopores can not only accommodate air molecules, but also allow air molecules to quickly enter and exit the micropores, so that the molecular sieve material has a good sound absorption effect. Since the mesopores and micropores are interconnected, the two can ensure rapid gas transmission, storage and convection. Therefore, the ratio of the pore volume of molecular sieve micropores and mesopores can also reflect the adsorption and desorption effects of molecular sieve materials to a certain extent.

Comparative examples 5 and 6 have a silicon-aluminum ratio between 800-4000, and the ratios of micropore volume and mesopore volume are 0.22 and 0.40 respectively, and they are compared with Example 2 and Example 4 for anti-aging performance experimental research. The results are shown in table 3.

Table 3 Changes in ΔF0 after adding samples in the speaker cavity

It can be seen from the data in Table 3 that the samples of Example 2, Example 4, Comparative Example 5, and Comparative Example 6 are filled in the rear cavity of the loudspeaker, all of which can reduce F0, and the difference is not obvious. However, after the sample absorbs water or VOCs components, and then test F0, it will be found that the molecular sieve samples (800<SAR<4000) of the embodiment of the application can still effectively reduce F0 (both>60); Comparative Examples 5 and 6 reduce The effect is poor, and the reduction value of F0 is between 30-60, indicating that the anti-aging performance of the sample is weak, that is, the sample of the embodiment of the present application has better anti-aging performance.

Generally, the higher the ratio of micropore volume to mesopore volume, the stronger the adsorption and desorption performance of air molecules, the greater the equivalent expansion ratio of the sound generating device box, and the better the effect of reducing the resonance frequency.

Especially when the ratio of micropore volume to mesopore volume is greater than 0.35 (comparative example 6 is 0.40), the micropore content of the molecular sieve is relatively high, and the size of most of the pore structure is small, which hinders the convection of air and the flow of air molecules. The entry and exit between molecular sieves affects the propagation of sound waves, and the effect of reducing F0 is significantly reduced.

Test the influence of the specific surface area of three micropores

The specific surface area of molecular sieve is another important parameter to evaluate the adsorption and desorption performance of sound-absorbing materials. Within a certain range, the larger the specific surface area of the sample, the stronger the adsorption capacity for air molecules and the better the effect of reducing the resonance frequency. Specific surface area includes external specific surface area and micropore specific surface area, among which micropore specific surface area is the main parameter affecting molecular sieve sound-absorbing materials.

Comparative examples 7 and 8 have a silicon-aluminum ratio between 800-4000, and the micropore volume and mesopore volume are about 0.25. The anti-aging performance experiment is carried out with Example 2 and Example 4, and the results are shown in Table 4 .

Table 4 Changes in ΔF0 after adding samples in the speaker cavity

It can be seen from the data in Table 4 that the samples of Example 2, Example 4, Comparative Example 7, and Comparative Example 8 are filled in the rear cavity of the loudspeaker, all of which can reduce F0, and the difference is not obvious. However, after the sample absorbs water or VOCs components, and then test F0, it will be found that the molecular sieve sample (800<SAR<4000) of the embodiment of the present application can still effectively reduce F0; the reduction of F0 in Comparative Example 7 and Comparative Example 8 All are poor, between 30-60, indicating that the anti-aging performance of the sample is relatively weak, that is, the sample of the embodiment of the present application has better anti-aging performance. Generally, the larger the specific surface area of micropores, the stronger the adsorption and desorption performance of air molecules, the larger the equivalent expansion ratio of the sound generating device box, and the better the effect of reducing the resonance frequency. However, when the micropore specific surface area is greater than 70m ² /g, the molecular sieve has a high micropore content, and most of the pore structures are small in size, which hinders the convection of air and the entry and exit of air molecules between the molecular sieves, thus affecting the acoustic wave. spread, the reduction effect on F0 drops significantly.

Test four micropores and mesoporous aperture effect

In comparative examples 9 and 10, the ratio of silicon to aluminum is between 800-4000, the pore volume of micropores and mesopores is about 0.25, the specific surface area of micropores is less than 72m2/g, and the pore diameter range of micropores and mesopores has been adjusted. , and carry out anti-aging performance experimental research with embodiment 2 and embodiment 4, the results are shown in table 5.

Table 5 Changes in ΔF0 after adding samples in the speaker cavity

It can be seen from the data in Table 5 that the samples of Example 2, Example 4, Comparative Example 9, and Comparative Example 10 are filled in the rear cavity of the loudspeaker, all of which can reduce F0, and the difference is not obvious. However, after the sample absorbs water or VOCs components, and then test F0, it will be found that the molecular sieve samples (800<SAR<4000) of the embodiment of the application can still effectively reduce F0 (both>60); Comparative Examples 9 and 10 reduce The effect is poor, between 30-60, indicating that the anti-aging performance of the sample is relatively weak, that is, the sample of the embodiment of the present application has better anti-aging performance.

Usually, the narrower the pore size range of the micropores in the molecular sieve sample, the more the number of micropores, which will increase the cumulative pore volume of the sample and improve the adsorption capacity for air molecules, while the narrower the pore size range of the mesopores, it means The higher the degree of perfection of the pores, the better the adsorption-desorption effect of air. If the pore diameter range of mesopores is too wide, the difference between the pore diameters of mesopores and micropores will be large, resulting in air molecules entering and leaving the micropores and the flow in the mesopores being blocked, thus affecting the propagation of sound waves and reducing the effect on F0 Significantly decreased.

Claims

The ZSM-5 molecular sieve used for sound-absorbing materials is characterized in that the silicon-aluminum mass ratio of the ZSM-5 molecular sieve is 800-4000, the micropore specific surface area is less than 72m 2 /g, and the micropore diameter ranges from 0.5-1.5nm Between, the mesopore diameter ranges between 2-10nm, and the ratio of the cumulative pore volume of the micropores to the cumulative pore volume of the mesopores is 0.24-0.35.
The ZSM-5 molecular sieve for sound-absorbing materials according to claim 1, wherein the micropore volume of the ZSM-5 molecular sieve is 0.043-0.050ml/g, and the mesopore volume is 0.16-0.21ml/g. g.
The ZSM-5 molecular sieve used for sound-absorbing materials according to claim 1, characterized in that, the ZSM-5 molecular sieve has an adsorption capacity of ≤1.25% for water, and after it is filled in the rear cavity of the speaker and absorbs water, it resonates The frequency change ΔF0 is still greater than 60Hz.
The preparation method of the ZSM-5 molecular sieve for sound-absorbing material according to any one of claims 1-3, is characterized in that, comprises the following steps:

Mix alkali source, aluminum source, template agent, silicon source, ZSM-5 molecular sieve seed with water to form a gel;

The obtained gel is placed in a reaction kettle, and a hydrothermal crystallization reaction is carried out under autogenous pressure. After the reaction is completed, solid-liquid separation, washing, drying, and roasting are carried out in sequence to obtain the molecular sieve powder;

The obtained molecular sieve raw powder is ion-exchanged with ammonium salt solution, filtered and separated to obtain a solid product, and the obtained solid product is repeatedly washed with deionized water until neutral, and the filter cake is dried and roasted by segmental microwaves to obtain ZSM-5 molecular sieve.
The preparation method according to claim 4, characterized in that, the molar ratio of added water, alkali source, aluminum source, templating agent, and silicon source is (2-10): (0.03-0.20): (0.00025-0.0033 ): (0.03-0.50): 1, wherein the silicon source is calculated as the silicon source oxide.
The preparation method according to claim 4, characterized in that, based on the mass of the silicon source oxide, the mass of the added ZSM-5 seed crystal is 3-8 wt%.
The preparation method according to claim 4, wherein the ammonium salt solution is selected from at least one of ammonium chloride, ammonium nitrate, and ammonium sulfate, with a concentration of 0.1-2mol/L and a solid-to-liquid ratio of 1: (1~10).
The preparation method according to claim 4, wherein the silicon source is selected from solid silica gel, silica sol, sodium silicate nonahydrate, silicon powder, white carbon black, diatomaceous earth, silicate and ethyl orthosilicate at least one of esters;

The alkali source is an alkali metal hydroxide, selected from sodium hydroxide or/and potassium hydroxide;

The templating agent is selected from diethylamine, tetraethylammonium bromide, tetraethylammonium chloride, tetraethylammonium hydroxide, tetrapropylammonium chloride, tetrapropylammonium bromide, tetrapropylammonium hydroxide, At least one of 1,6-hexanediamine;

The aluminum source is selected from at least one of aluminum hydroxide, pseudoboehmite, aluminum sulfate, sodium metaaluminate, aluminum isopropoxide, aluminum nitrate, aluminum oxide, and aluminum chloride.
The preparation method according to claim 4, characterized in that, in the step of obtaining the ZSM-5 molecular sieve, the staged microwave drying is specifically carried out in two stages, wherein the first stage microwave drying temperature is 10-20°C, and the time is 0.5-3h; the second microwave drying temperature is 20-30°C, and the time is 0.5-3h; the roasting temperature is 550-600°C.
The preparation method according to claim 4, characterized in that, in the step of obtaining the raw molecular sieve powder, the hydrothermal crystallization temperature is 150-200°C, the crystallization time is 20-48h; the drying temperature is 10-30°C, The firing temperature is 550-600°C.
The sound-absorbing material is characterized in that it is prepared by using the ZSM-5 molecular sieve described in any one of claims 1-3.
The sound-absorbing material according to claim 11, characterized in that, the ZSM-5 molecular sieve is packaged in the form of powder, granule, block, molecular sieve film or powder/granule/block as content present in at least one form.
The acoustic component is characterized in that it is prepared by using the sound-absorbing material described in claim 11 or 12.
The loudspeaker device is characterized in that it is prepared by using the sound-absorbing material described in claim 11 or 12.