New sound-absorbing materials - ION molecular sieve, molecular sieve microspheres and their preparation methods and applications

Abstract

The present invention discloses a novel sound-absorbing material, ION molecular sieve, molecular sieve microspheres, and a preparation method and application thereof, and relates to the technical field of loudspeakers. The preparation method of the ION molecular sieve comprises the following steps: uniformly mixing a silicon-containing compound with ammonium fluoride or hydrofluoric acid, an organic template, and water to obtain a mixed gel; the organic template is a double-headed organic compound with a quaternary ammonium salt cation as an end group, having a structural formula shown in the following formula (I), wherein the number of carbon chains of the R1 end group in formula (1) is selected from 2 or 3, and the anion H ‑ OH ‑ The mixed gel was transferred to a stainless steel autoclave and heated. The solid phase crystals were filtered, washed, dried, and calcined to obtain the novel sound-absorbing material, ION molecular sieve. The preparation method is simple, the raw materials are widely available and highly utilized, the product structure is novel, and the crystallinity is excellent. The prepared molecular sieve microspheres are uniform in particle size and exhibit no noticeable powder shedding. Testing has shown that the speaker's resonant frequency significantly improves low-frequency acoustic performance.

Description

Technical Field

[0001] The present invention relates to the technical field of loudspeakers, and in particular to a novel sound-absorbing material - ION molecular sieve, molecular sieve microspheres, and a preparation method and application thereof. Background Art

[0002] A loudspeaker is a device that converts electrical signals into sound signals. It consists of a vibration system and a radiation system. The interaction between these two systems affects the speaker's frequency response, low-frequency extension, and resonance characteristics. Traditional loudspeaker designs often incorporate fillers into the rear cavity. Fillers can effectively adjust the speaker's acoustic parameters, such as increasing the effective volume of the rear cavity and reducing resonances and standing waves. They can also reduce sound reflections and interference within the speaker and improve uniform sound radiation.

[0003] The research on molecular sieves as fillers for the back cavity of loudspeakers has been a new field in recent years. Molecular sieves are porous materials with a regular pore structure and a high specific surface area. They can adjust the propagation and absorption characteristics of sound waves by selecting the appropriate pore size and pore structure. The pore size and pore structure of molecular sieves can be customized to accommodate sound waves of different frequency ranges. Molecular sieves have the following advantages as fillers for the back cavity of loudspeakers: 1. Molecular sieves have a large specific surface area and adsorption properties, which can effectively absorb the energy in sound and reduce sound reflection and interference; 2. By selecting molecular sieves with different pore sizes and pore structures, the propagation characteristics of sound in the back cavity of the loudspeaker can be modulated to achieve a more even and balanced sound field distribution; 3. The pore size of the molecular sieve can be used to adjust the low-frequency extension and resonance characteristics of the sound, thereby improving the low-frequency effect of the loudspeaker.

[0004] Research on molecular sieves as loudspeaker fillers is still in its infancy, but some progress has been made. For example, Chinese patent publications CN113184876B and CN106792387B report that only a few molecular sieve topologies, such as FER, MFI, MEL, and Beta, are currently used to improve low-frequency performance in loudspeakers. To date, the International Molecular Sieve Association's website has published a total of 255 molecular sieve topologies.

[0005] Therefore, those skilled in the art are committed to developing a new molecular sieve structure to further broaden the application of molecular sieve materials in the field of speakers, which is an urgent problem to be solved by the present invention. Summary of the Invention

[0006] In view of the above-mentioned defects of the prior art, the technical problem to be solved by the present invention is to provide a new molecular sieve structure to further broaden the application of molecular sieve materials in the field of speakers.

[0007] To achieve the above object, the present invention provides a method for preparing a novel sound-absorbing material - ION molecular sieve, comprising the following steps:

[0008] Step 1: uniformly mix a silicon-containing compound with ammonium fluoride or hydrofluoric acid, an organic template, and water to obtain a mixed gel; wherein the organic template is a double-headed organic compound with a quaternary ammonium salt cation as an end group, and has a structural formula as shown in the following formula (I), wherein the number of carbon chains of the R1 end group in formula (1) is selected from 2 or 3, and the anion H - OH - ;

[0009]

[0010] Step 2: Transfer the mixed gel to a stainless steel high-pressure reactor and heat it. The solid phase crystals are filtered, washed, dried and calcined to obtain a new sound-absorbing material - ION molecular sieve.

[0011] In a preferred embodiment of the present invention, in step 1, the molar ratio of the silicon-containing compound to ammonium fluoride or hydrofluoric acid, the organic template, and water is 1.0:0.2-0.25:0.3-0.4:20-40.

[0012] In a preferred embodiment of the present invention, in step 1, the silicon-containing compound is selected from any one of tetraethyl orthosilicate calculated as SiO2, fumed silica gel calculated as SiO2, and silica sol calculated as SiO2.

[0013] In a preferred embodiment of the present invention, in step 1, a metal compound is further added, and the metal compound is selected from any one of tetrabutyl titanate, aluminum isopropoxide or sodium metaaluminate.

[0014] Furthermore, the molar ratio of the silicon-containing compound to the metal compound is 1:0.05-0.08.

[0015] The present invention also discloses a method for preparing a novel sound-absorbing material - ION molecular sieve microspheres, which is characterized in that the preparation is carried out using the above-mentioned sound-absorbing material - ION molecular sieve, and comprises the following steps:

[0016] Step 3: evenly dispersing the sound-absorbing material-ION molecular sieve powder and calcium carbonate in the sodium alginate aqueous solution to form a homogeneous emulsion;

[0017] Step 4: slowly pouring the homogeneous emulsion into paraffin oil mixed with an emulsifier and stirring to obtain dispersed droplets of target size;

[0018] Step 5: adjusting the pH of the dispersed droplets to release calcium ions from the droplets and cause a cross-linking reaction with sodium alginate;

[0019] Step 6: After the reaction is completed, the residual paraffin oil and impurities on the surface are washed repeatedly with ethanol and water alternately to obtain white spherical particles;

[0020] Step 7: Filter, dry, and calcine the white spherical particles to completely remove organic matter, thereby obtaining the novel titanium-containing sound-absorbing material - ION structure molecular sieve microspheres.

[0021] In a preferred embodiment of the present invention, in step 3, the mass ratio of the calcium carbonate, the sound-absorbing material (ION molecular sieve powder), the sodium alginate and the water is 1:10-20:1.1:66.7-166.7.

[0022] In a preferred embodiment of the present invention, in step 4, in the paraffin oil mixed with the emulsifier, the emulsifier and the paraffin oil are mixed in a volume ratio of 1:30.

[0023] In a preferred embodiment of the present invention, in step 7, the white spherical particles are filtered and then placed in an environment of 80° C. for drying for 12 hours, and then calcined at a high temperature of 600° C. for 6 hours.

[0024] The present invention also discloses the use of the novel sound-absorbing material, ION molecular sieve microspheres, in preparing loudspeaker fillers.

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] The -ION molecular sieve prepared by the present invention has sharp characteristic diffraction peaks as analyzed by X-ray powder diffractometer, which proves that it has good crystallinity; scanning electron microscopy shows that the -ION structure molecular sieve as a whole presents the morphology characteristics of nanosheets; nitrogen adsorption and desorption experiments prove that the specific surface area of the -ION structure molecular sieve is 400-500m 2 ·g -1 .

[0027] The present invention has many characteristics such as simple preparation method, wide source of raw materials and high utilization rate, novel product structure and good crystallinity. The prepared molecular sieve microspheres have uniform particle size and no obvious powder falling phenomenon. After testing on an acoustic test platform, with the blank of the speaker rear cavity as the control, the low-frequency resonance frequency decreased by 318.309, 321.292, 322.789 and 323.425 Hz respectively. The resonance frequency of the speaker has changed significantly, which is reflected in the significant improvement in the low-frequency acoustic performance.

[0028] The concept, specific structure and technical effects of the present invention will be further described below in conjunction with the accompanying drawings to fully understand the purpose, characteristics and effects of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1This is the X-ray diffraction spectrum of the -ION molecular sieve prepared by the present invention;

[0030] Figure 2 This is a scanning electron microscope image of the -ION molecular sieve prepared in the present invention;

[0031] Figure 3 This is a nitrogen adsorption and desorption curve of the -ION molecular sieve prepared by the present invention;

[0032] Figure 4 This is an optical microscope image of the -ION molecular sieve microspheres prepared in the present invention. DETAILED DESCRIPTION

[0033] The following describes several preferred embodiments of the present invention with reference to the accompanying drawings to make its technical content clearer and easier to understand. The present invention can be embodied in many different forms of embodiments, and the scope of protection of the present invention is not limited to the embodiments mentioned herein.

[0034] In the drawings, components with identical structures are denoted by the same reference numerals, and components with similar structures or functions are denoted by similar reference numerals. The size and thickness of each component shown in the drawings are arbitrary and are not limited by the present invention. For clarity, the thickness of components in some places in the drawings is appropriately exaggerated.

[0035] In the following embodiments of the present invention, the organic template is a double-headed organic compound with a quaternary ammonium salt cation as the terminal group, having a structural formula as shown in the following formula (I), wherein the carbon chain number n of the R1 terminal group in formula (I) is selected from 2 or 3, and the anion H - OH - .

[0036]

[0037] The following describes the invention through specific embodiments.

[0038] Example 1

[0039] Step 1: Tetraethyl orthosilicate, tetrabutyl titanate, ammonium fluoride, organic template and water are mixed in a molar ratio of 1.0:0.05:0.2:0.3:20, and stirred at room temperature for 24 hours until the mixture is uniform to obtain a uniform mixed gel. The organic template has a carbon chain number n of 3 at the R1 end group, and an anion H - OH - .

[0040] Step 2: Transfer the mixed gel to a stainless steel autoclave and heat it at 150°C for 15 days. The solid phase crystals are filtered, washed, dried and calcined to obtain a new sound-absorbing material containing titanium - ION structure molecular sieve.

[0041] See Figure 1 The novel sound-absorbing material containing titanium prepared in Example 1 - ION structure molecular sieve has the X-ray diffraction structure data (Cu-Kα, ):

[0042] Table 1: X-ray diffraction structure data of -ION molecular sieve

[0043]

[0044]

[0045] In the table: (a) is the relative intensity level of the diffraction peak in the powder X-ray diffraction spectrum, W is a weak diffraction peak, its value is less than 25; M is a medium diffraction peak, its value is 25-50; S is a strong diffraction peak, its value is 50-75; VS is the strongest diffraction peak, its value is 75-100.

[0046] See Figure 2 The new sound-absorbing material prepared in Example 1 - ION structure molecular sieve was shown to have a nanosheet structure morphology by scanning electron microscopy.

[0047] See Figure 3 The new sound-absorbing material prepared in Example 1, the ION structure molecular sieve, was tested by nitrogen adsorption and desorption experiments. It has an obvious microporous structure and a specific surface area of 400 to 500 m 2 ·g -1 .

[0048] See Figure 4 The novel sound-absorbing material prepared in Example 1 - ION structure molecular sieve is prepared by conventional alginate gel method. The molecular sieve microspheres are observed under an optical microscope to have uniform particle size, smooth surface and no powder falling.

[0049] Example 2

[0050] Step 1: Mix fuming silica gel calculated as SiO2 with aluminum isopropoxide, hydrofluoric acid, organic template and water in a molar ratio of 1.0:0.08:0.25:0.4:30, and stir at room temperature for 20 hours until the mixture is uniform to obtain a uniform mixed gel. The organic template has a carbon chain of R1 end group n of 2, and an anion H - OH - .

[0051] Step 2: Transfer the above-mentioned uniformly mixed gel to a stainless steel high-pressure reactor and heat it at 170°C for 12 days. The solid phase crystals are filtered, washed, dried and calcined to obtain a new aluminum-containing sound-absorbing material - ION structure molecular sieve.

[0052] Example 3

[0053] Step 1: Mix silica sol calculated as SiO2 with sodium metaaluminate, hydrofluoric acid, organic template and water in a molar ratio of 1.0:0.08:0.2:0.4:40, and stir at room temperature for 25 hours until the mixture is uniform to obtain a uniform mixed gel. The organic template has a carbon chain of R1 end group n of 3, an anion H - OH - .

[0054] Step 2: Transfer the mixed gel to a stainless steel autoclave and heat it at 170°C for 15 days. The solid phase crystals are filtered, washed, dried and calcined to obtain a new aluminum-containing sound-absorbing material - ION structure molecular sieve.

[0055] Example 4

[0056] Step 1: Mix silica sol calculated as SiO2 with ammonium fluoride, organic template and water in a molar ratio of 1.0:0.2:0.3:35, and stir at room temperature for 20 hours until the mixture is uniform to obtain a uniform mixed gel. The organic template has an R1 terminal carbon chain n of 2 and an anion H - OH - .

[0057] Step 2: Transfer the mixed gel to a stainless steel autoclave and heat it at 160°C for 16 days. The solid phase crystals are filtered, washed, dried and calcined to obtain a new all-silicon sound-absorbing material - ION structure molecular sieve.

[0058] The application of the present invention is further described below by using the alginate gel method to prepare the novel sound-absorbing material - ION structure molecular sieve prepared in Examples 1 to 4 into molecular sieve microspheres for improving the low-frequency acoustic performance of a loudspeaker.

[0059] Example 5

[0060] Step 1: The new titanium-containing sound-absorbing material prepared in Example 1 - ION structure molecular sieve powder and insoluble calcium carbonate salt are evenly mixed in an alginate (preferably sodium alginate) aqueous solution, and then slowly poured into paraffin oil mixed with an emulsifier, and stirred at a constant speed for 10 minutes during the process to obtain dispersed droplets of the target size. Subsequently, glacial acetic acid is added to adjust the pH so that calcium ions are released from the inside of the droplets and undergo a cross-linking reaction with the alginate. Among them, calcium carbonate, molecular sieve, sodium alginate and water are mixed in a mass ratio of 1:10-20:1.1:66.7-166.7, and the emulsifier and paraffin oil are mixed in a volume ratio of 1:30. The amount of acetic acid added is 2.5 mL, the stirring speed is 550-1000 rpm, and the duration is 10 minutes. Among them, the optimal amount of molecular sieve added is 20 g, the optimal amount of water added is 96.7 g, and the optimal stirring speed is 800 rpm.

[0061] Step 2: Allow the alginate to react fully for 24 hours. Residual paraffin oil and impurities on the surface are washed off repeatedly with ethanol and water, yielding white spherical microparticles. After filtration, the microparticles are dried at 80°C for 12 hours and calcined at 600°C for 6 hours to completely remove organic matter, yielding the novel titanium-containing sound-absorbing material—ION-structured molecular sieve microspheres.

[0062] Step 3: The novel titanium-containing sound-absorbing material (ION-structured molecular sieve microspheres) prepared above was evenly filled into a microspeaker with a 1cc rear cavity. The cavity was completely sealed with an acrylic back cover. Subsequently, parameters such as the rated input power, sweep frequency range, and sweep frequency step size were set on the acoustic test platform. An electrical signal was connected to the microspeaker's signal input interface to test its acoustic performance, which was correlated with the impedance curve (Table 2).

[0063] Example 6

[0064] Step 1: The new aluminum-containing sound-absorbing material prepared in Example 2 - ION structure molecular sieve powder and insoluble calcium carbonate salt are evenly mixed in an alginate (preferably sodium alginate) aqueous solution, and then slowly poured into paraffin oil mixed with an emulsifier, and stirred at a constant speed for 10 minutes during the process to obtain dispersed droplets of the target size. Subsequently, glacial acetic acid is added to adjust the pH so that calcium ions are released from the inside of the droplets and undergo a cross-linking reaction with the alginate. Among them, calcium carbonate, molecular sieve, sodium alginate and water are mixed in a mass ratio of 1:10-20:1.1:66.7-166.7, and the emulsifier and paraffin oil are mixed in a volume ratio of 1:30. The amount of acetic acid added is 2.5 mL, the stirring speed is 550-1000 rpm, and the duration is 10 minutes. Among them, the optimal addition amount of molecular sieve is 20 g, the optimal addition amount of water is 96.7 g, and the optimal stirring speed is 800 rpm.

[0065] Step 2: The sample was allowed to stand for 24 hours to allow the alginate to fully react. Residual paraffin oil and impurities on the surface were washed off repeatedly with ethanol and water, yielding white spherical microparticles. After filtration, the microparticles were dried at 80°C for 12 hours and calcined at 600°C for 6 hours to completely remove organic matter, yielding the novel aluminum-containing sound-absorbing material—ION-structured molecular sieve microspheres.

[0066] Step 3: The novel aluminum-containing sound-absorbing material (ION-structured molecular sieve microspheres) prepared above was evenly filled into a microspeaker with a 1cc rear cavity. The cavity was completely sealed with an acrylic back cover. Subsequently, parameters such as rated input power, sweep frequency range, and sweep frequency step size were set on the acoustic test platform. An electrical signal was connected to the microspeaker's signal input interface to test its acoustic performance, which was correlated with the impedance curve (Table 2).

[0067] Example 7

[0068] Step 1: The new aluminum-containing sound-absorbing material prepared in Example 3 - ION structure molecular sieve powder and insoluble calcium carbonate salt are evenly mixed in an alginate (preferably sodium alginate) aqueous solution, and then slowly poured into paraffin oil mixed with an emulsifier, and stirred at a constant speed for 10 minutes during the process to obtain dispersed droplets of the target size. Subsequently, glacial acetic acid is added to adjust the pH so that calcium ions are released from the inside of the droplets and undergo a cross-linking reaction with the alginate. Among them, calcium carbonate, molecular sieve, sodium alginate and water are mixed in a mass ratio of 1:10-20:1.1:66.7-166.7, and the emulsifier and paraffin oil are mixed in a volume ratio of 1:30. The amount of acetic acid added is 2.5 mL, the stirring speed is 550-1000 rpm, and the duration is 10 minutes. Among them, the optimal addition amount of molecular sieve is 20 g, the optimal addition amount of water is 96.7 g, and the optimal stirring speed is 800 rpm.

[0069] Step 2: The sample was allowed to stand for 24 hours to allow the alginate to fully react. Residual paraffin oil and impurities on the surface were washed off repeatedly with ethanol and water, yielding white spherical microparticles. After filtration, the microparticles were dried at 80°C for 12 hours and calcined at 600°C for 6 hours to completely remove organic matter, yielding the novel aluminum-containing sound-absorbing material—ION-structured molecular sieve microspheres.

[0070] Step 3: The novel aluminum-containing sound-absorbing material (ION-structured molecular sieve microspheres) prepared above was evenly filled into a microspeaker with a 1cc rear cavity. The cavity was completely sealed with an acrylic back cover. Subsequently, parameters such as rated input power, sweep frequency range, and sweep frequency step size were set on the acoustic test platform. An electrical signal was connected to the microspeaker's signal input interface to test its acoustic performance, which was correlated with the impedance curve (Table 2).

[0071] Example 8

[0072] Step 1: The novel all-silicon sound-absorbing material prepared in Example 4, the ION-structured molecular sieve powder, and the insoluble calcium carbonate salt are uniformly mixed in an aqueous solution of alginate (preferably sodium alginate). Subsequently, the mixture is slowly poured into paraffin oil mixed with an emulsifier, while maintaining a constant stirring speed for 10 minutes to obtain dispersed droplets of the target size. Subsequently, glacial acetic acid is added to adjust the pH, allowing calcium ions to be released from the droplets and undergo a cross-linking reaction with the alginate. The calcium carbonate, molecular sieve, sodium alginate, and water are mixed in a mass ratio of 1:10-20:1.1:66.7-166.7, and the emulsifier and paraffin oil are mixed in a volume ratio of 1:30. The amount of acetic acid added is 2.5 mL, and the stirring speed is 550-1000 rpm for 10 minutes. The optimal amount of molecular sieve added is 20 g, the optimal amount of water added is 96.7 g, and the optimal stirring speed is 800 rpm.

[0073] Step 2: Allow the alginate to react fully for 24 hours. Residual paraffin oil and impurities on the surface are washed off repeatedly with ethanol and water, yielding white spherical microparticles. After filtration, the particles are dried at 80°C for 12 hours and calcined at 600°C for 6 hours to completely remove organic matter, yielding the novel all-silica sound-absorbing material—ION-structured molecular sieve microspheres.

[0074] Step 3: The novel all-silicon sound-absorbing material (ION-structured molecular sieve microspheres) prepared above was evenly filled into a microspeaker with a 1cc rear cavity. The cavity was completely sealed with an acrylic back cover. Subsequently, parameters such as the rated input power, sweep frequency range, and sweep frequency step were set on the acoustic test platform. An electrical signal was connected to the microspeaker's signal input interface to test its acoustic performance, which was correlated with the impedance curve (Table 2).

[0075] Table 2: Resonance frequency differences when a new sound-absorbing material, ION-structured molecular sieve microspheres, is added to the rear cavity of the speaker.

[0076] serial number F(Hz) △F(Hz) blank 788.518 0.000 Example 5 470.209 318.309 Example 6 467.226 321.292 Example 7 465.729 322.789 Example 8 465.093 323.425

[0077] According to Table 2, after the new sound-absorbing material - ION structure molecular sieve microspheres of Examples 1 to 4 is filled in the rear cavity of the speaker, the change in the resonance frequency ΔF (Hz) of the speaker is greatly reduced.

[0078] The preferred embodiments of the present invention have been described in detail above. It should be understood that numerous modifications and variations based on the concepts of the present invention are possible without inventive effort by those skilled in the art. Therefore, any technical solution that can be derived by one skilled in the art through logical analysis, reasoning, or limited experimentation based on the concepts of the present invention and the prior art should be within the scope of protection defined by the claims.

Claims

1. Application of a novel sound-absorbing material, ION molecular sieve microspheres, in the preparation of loudspeaker fillers, wherein the application is to reduce the variation in the resonant frequency of the loudspeaker; a method for preparing the novel sound-absorbing material, ION molecular sieve microspheres, comprises the following steps: Step 1: uniformly mix a silicon-containing compound with ammonium fluoride or hydrofluoric acid, an organic template, and water to obtain a mixed gel; the organic template is a double-headed organic compound with a quaternary ammonium salt cation as an end group, having a structural formula shown in the following formula (I), wherein: In formula (I), the number of carbon chains of the R1 terminal group is selected from 2 or 3, and the anion H - OH - ; Step 2: Transfer the mixed gel to a stainless steel autoclave and heat it; filter, wash, dry and calcine the solid phase crystals to obtain a new sound-absorbing material - ION molecular sieve; Step 3: evenly dispersing the sound-absorbing material-ION molecular sieve powder and calcium carbonate in the sodium alginate aqueous solution to form a homogeneous emulsion; Step 4: slowly pouring the homogeneous emulsion into paraffin oil mixed with an emulsifier and stirring to obtain dispersed droplets of target size; Step 5: adjusting the pH of the dispersed droplets to release calcium ions from the droplets and cause a cross-linking reaction with sodium alginate; Step 6: After the reaction is completed, the residual paraffin oil and impurities on the surface are washed repeatedly with ethanol and water alternately to obtain white spherical particles; Step 7: filtering, drying, and calcining the white spherical particles to completely remove organic matter, thereby obtaining the novel titanium-containing sound-absorbing material - ION structure molecular sieve microspheres; In step 1, the silicon-containing compound is selected from any one of tetraethyl orthosilicate calculated as SiO2, fumed silica gel calculated as SiO2, and silica sol calculated as SiO2; In step 1, a metal compound is also added, and the metal compound is selected from tetrabutyl titanate; In step 1, the molar ratio of the silicon-containing compound to ammonium fluoride or hydrofluoric acid, the organic template, and water is 1.0:0.2-0.25:0.3-0.4:20-40; The molar ratio of the silicon-containing compound to the metal compound is 1:0.05-0.08; In step 3, the mass ratio of the calcium carbonate, the sound-absorbing material-ION molecular sieve powder, the sodium alginate and the water is 1:10-20:1.1:66.7-166.7; In step 4, the paraffin oil mixed with the emulsifier is mixed with the paraffin oil at a volume ratio of 1:30; In step 7, the white spherical particles are filtered and placed in an environment of 80° C. for drying for 12 hours, and then calcined at a high temperature of 600° C. for 6 hours.

Images