CN112978708B - Preparation method of carbon molecular sieve sound-absorbing material - Google Patents
Preparation method of carbon molecular sieve sound-absorbing material Download PDFInfo
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- CN112978708B CN112978708B CN202110079552.6A CN202110079552A CN112978708B CN 112978708 B CN112978708 B CN 112978708B CN 202110079552 A CN202110079552 A CN 202110079552A CN 112978708 B CN112978708 B CN 112978708B
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- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
- C01B32/00—Carbon; Compounds thereof
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- G—PHYSICS
- G10—MUSICAL INSTRUMENTS; ACOUSTICS
- G10K—SOUND-PRODUCING DEVICES; METHODS OR DEVICES FOR PROTECTING AGAINST, OR FOR DAMPING, NOISE OR OTHER ACOUSTIC WAVES IN GENERAL; ACOUSTICS NOT OTHERWISE PROVIDED FOR
- G10K11/00—Methods or devices for transmitting, conducting or directing sound in general; Methods or devices for protecting against, or for damping, noise or other acoustic waves in general
- G10K11/16—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general
- G10K11/162—Selection of materials
Abstract
The invention discloses a preparation method of a carbon molecular sieve sound-absorbing material, which comprises the following steps: s1: selecting a molecular sieve with the diameter of micropores larger than 2nm as a template agent, and drying; s2: mixing and stirring a molecular sieve used as a template agent and low-carbon liquid in a protective gas atmosphere; s3: washing and drying the solid sample for multiple times by adopting mesitylene; s4: vacuumizing; s5: after uniform temperature rise, keeping constant temperature, and then quickly heating for carbonization; forming mixed gas of low-carbon gas and nitrogen or argon as protective gas, filling the mixed gas into the tubular furnace, and switching the protective gas into dry argon; s6: heating the molecular sieve-carbon composite to a specified temperature within 1h, and quenching; s7: transferring the molecular sieve-carbon composite into an acid or alkali solution, centrifugally collecting the carbon molecular sieve, washing the carbon molecular sieve with deionized water for several times, and drying to obtain the carbon molecular sieve; s8: mixing the carbon molecular sieve with a binder to form sound-absorbing particles with the particle size of 200-500 mu m. The invention can improve the stability of the acoustic performance of the loudspeaker.
Description
Technical Field
The invention relates to the field of loudspeakers, in particular to a preparation method of a carbon molecular sieve sound-absorbing material.
Background
With the increasing miniaturization of consumer electronics, the size of the speaker in portable electronic devices such as mobile phones and tablet computers is smaller and smaller, and the performance requirements of the speaker in the market are higher and higher. In order to improve the acoustic performance of the speaker module (for example, reduce the resonant frequency F0 of the speaker and improve the stability in use), a sound-absorbing material is usually added to the back sound cavity of the speaker, and the sound-absorbing material utilizes the pores generated by the interior of the sound-absorbing material and the accumulation to increase the effective volume of the back sound cavity, so that the air molecules consume the kinetic energy of the air molecules through the processes of diffusion, adsorption, desorption, collision and the like in the interior of the material and the pores generated by the accumulation, thereby achieving the effects of consuming part of sound energy, reducing radiation interference and weakening distortion. Currently, the commonly used sound-absorbing materials include activated carbon, silica, zeolite molecular sieves and the like.
In the prior art, the framework structure of zeolite molecules mainly comprises silicon or silicon-aluminum, and the zeolite molecular sieve is easy to adsorb moisture in air at room temperature and occupies micropores, so that the low-frequency performance of the zeolite molecular sieve is not high, and the performance of a loudspeaker is reduced.
Disclosure of Invention
The technical problem to be solved by the invention is as follows: the preparation method of the carbon molecular sieve sound-absorbing material is provided, and the stability of the performance of the loudspeaker is improved.
In order to solve the technical problems, the invention adopts the technical scheme that:
a preparation method of a carbon molecular sieve sound-absorbing material comprises the following steps:
s1: selecting a molecular sieve with the micropore diameter larger than 2nm as a template, drying and degassing the molecular sieve as the template for 6-24 h under the conditions that the temperature is 150-450 ℃ and the container is in vacuum, and then cooling to room temperature for later use;
s2: mixing and stirring a certain amount of molecular sieve and a certain amount of low-carbon liquid with 1-5 carbon atoms in a protective gas atmosphere to obtain a mixture, carrying out vacuum filtration on the mixture, and collecting a solid sample;
s3: cleaning a solid sample for multiple times by adopting mesitylene, drying the solid sample, placing the dried sample in an alumina crucible and transferring the dried sample to a tubular furnace;
s4: vacuumizing the tube furnace, filling the tube furnace with dry argon until the pressure in the tube furnace reaches 1 mbar-1 bar, and keeping the flow rate of the argon at 100 mL/min-300 mL/min;
s5: raising the temperature to 70-120 ℃ at a constant speed, keeping the temperature for 12-36 h, then quickly heating to 600-800 ℃ for carbonization, wherein the carbonization time is 1-3 h;
forming a mixed gas of a low-carbon gas with 1-5 carbon atoms and nitrogen or argon as a protective gas, filling the mixed gas into the tubular furnace, and switching the protective gas into dry argon after 1-5 hours;
s6: heating the molecular sieve-carbon composite to 800-1100 ℃ within 1h, quenching for 2-5 h, cooling overnight, and closing gas;
s7: transferring the molecular sieve-carbon composite into an acid or alkali solution, replacing the acid or alkali solution for 1-3 times, centrifugally collecting the carbon molecular sieve, washing the carbon molecular sieve with deionized water for several times, and drying the carbon molecular sieve in air at 60-100 ℃ to obtain the carbon molecular sieve;
s8: mixing the carbon molecular sieve with a binder to form sound-absorbing particles with the particle size of 200-500 mu m.
The invention has the beneficial effects that: the molecular sieve-carbon composite with the micropore tissue and the mesoporous tissue is prepared by adopting a molecular sieve with larger micropore diameter as a template agent through a thermal cracking mode, and the proportion of the micropore tissue and the mesoporous tissue is adjusted through acid treatment or alkali treatment, so that air molecules can smoothly enter the sound-absorbing material, the rapid adsorption and desorption and diffusion properties of the sound-absorbing material to the gas in the back cavity of the loudspeaker are facilitated, the damping of the loudspeaker is reduced, the low-frequency response of the loudspeaker is improved, and the low-frequency acoustic performance of the loudspeaker is improved. Compared with the sound-absorbing material made of a common molecular sieve, the sound-absorbing material made of the molecular sieve has a mesoporous structure and a hydrophobic structure, so that the sound-absorbing material has better hydrophobicity, and the problem of reduction of the stability of a loudspeaker due to excessive moisture adsorption can be effectively avoided.
Drawings
FIG. 1 is an X-ray diffraction pattern of a carbon molecular sieve prepared in accordance with example two of the present invention;
FIG. 2 is an X-ray diffraction diagram of a carbon molecular sieve prepared in example three of the present invention;
FIG. 3 is an X-ray diffraction pattern of a carbon molecular sieve prepared in accordance with example four of the present invention;
FIG. 4 is a graph comparing frequency response and impedance curves of a speaker back cavity without adding carbon molecular sieve and with adding carbon molecular sieve of example III.
Detailed Description
In order to explain technical contents, achieved objects, and effects of the present invention in detail, the following description is made with reference to the accompanying drawings in combination with the embodiments.
A preparation method of a carbon molecular sieve sound-absorbing material comprises the following steps:
s1: selecting a molecular sieve with the diameter of micropores larger than 2nm as a template, drying and degassing the molecular sieve as the template for 6-24 h at the temperature of 150-450 ℃ under the condition that a container is in vacuum, and then cooling to room temperature for later use;
s2: mixing and stirring a certain amount of molecular sieve and a certain amount of low-carbon liquid with 1-5 carbon atoms in a protective gas atmosphere to obtain a mixture, carrying out vacuum filtration on the mixture, and collecting a solid sample;
s3: cleaning a solid sample for multiple times by adopting mesitylene, drying the solid sample, placing the dried sample in an alumina crucible and transferring the dried sample to a tubular furnace;
s4: vacuumizing the tube furnace, filling the tube furnace with dry argon until the pressure in the tube furnace reaches 1 mbar-1 bar, and keeping the flow rate of the argon at 100 mL/min-300 mL/min;
s5: raising the temperature to 70-120 ℃ at a constant speed, keeping the temperature for 12-36 h, then quickly heating to 600-800 ℃ for carbonization for 1-3 h;
forming a mixed gas of a low-carbon gas with 1-5 carbon atoms and nitrogen or argon as a protective gas, filling the mixed gas into the tubular furnace, and switching the protective gas into dry argon after 1-5 hours;
s6: heating the molecular sieve-carbon composite to 800-1100 ℃ within 1h, quenching for 2-5 h, cooling overnight, and closing gas;
s7: transferring the molecular sieve-carbon composite into an acid or alkali solution, replacing the acid or alkali solution for 1-3 times, centrifugally collecting the carbon molecular sieve, washing the carbon molecular sieve with deionized water for several times, and drying the carbon molecular sieve in air at 60-100 ℃ to obtain the carbon molecular sieve;
s8: mixing the carbon molecular sieve with a binder to form sound absorption particles with the particle size of 200-500 mu m.
The working principle of the invention is as follows:
the molecular sieve-carbon composite with the micropore structure and the mesoporous structure is prepared by using a molecular sieve with larger micropore diameter as a template agent in a thermal cracking mode, and is subjected to acid treatment or alkali treatment to prepare the sound-absorbing material, so that air molecules can smoothly enter the material, the sound-absorbing material has good hydrophobicity, and the stability of the performance of the loudspeaker is improved.
From the above description, the beneficial effects of the present invention are: the molecular sieve-carbon composite with the micropore tissue and the mesoporous tissue is prepared by adopting a molecular sieve with larger micropore diameter as a template agent through a thermal cracking mode, and the proportion of the micropore tissue and the mesoporous tissue is adjusted through acid treatment or alkali treatment, so that air molecules can smoothly enter the sound-absorbing material, the rapid adsorption and desorption and diffusion properties of the sound-absorbing material to the gas in the back cavity of the loudspeaker are facilitated, the damping of the loudspeaker is reduced, the low-frequency response of the loudspeaker is improved, and the low-frequency acoustic performance of the loudspeaker is improved. Compared with the sound-absorbing material made of a common molecular sieve, the sound-absorbing material made of the molecular sieve has a mesoporous structure and a hydrophobic structure, so that the sound-absorbing material has better hydrophobicity, and the problem of reduction of the stability of a loudspeaker due to excessive moisture adsorption can be effectively avoided.
Further, the specific step of S8 is: mixing a carbon molecular sieve and water according to the weight ratio of 1: (1-10) are mixed into composite molecular sieve powder water dispersion;
mixing a binder with a solid content of 50% and water according to a ratio of 1: (1-4) to obtain a binder water dispersion;
and (3) mixing the composite molecular sieve powder aqueous dispersion and the binder aqueous dispersion according to the ratio of (2-10): 1 to obtain a mixture;
the mixture is spray-dried in a spray dryer under the spray pressure of 0.02MPa to 0.1MPa and the drying temperature of 80 ℃ to 120 ℃ to form the sound-absorbing particles.
It can be known from the above description that, since the particle size of the dried carbon molecular sieve is small, the carbon molecular sieve is directly filled in the rear sound cavity of the speaker, which easily causes powder leakage and flows into other areas of the speaker, thereby affecting the normal operation of the speaker. Therefore, the carbon molecular sieve and the binder are mixed to form larger sound absorption particles, and then the larger sound absorption particles are filled into a rear sound cavity of the loudspeaker, so that the acoustic performance of the loudspeaker is ensured.
Furthermore, the binder is one or more of polyacrylic binders, polyacrylic ester binders, polyvinyl acetate binders, polystyrene binders or polyurethane binders.
Further, the vacuum degree in the S1 is 10 -3 ～5×10 -3 mbar。
Further, the low-carbon gas in the S5 is carbon monoxide, propylene or formaldehyde.
Further, the molecular sieve used as the template in S1 is NaY molecular sieve, BEA, EMT, FAU, IRR or ISV.
According to the above description, the above molecular sieves as the template agents are all template agents with large micropore diameters, and after subsequent thermal cracking and acid treatment or alkali treatment, a micropore structure with large pore diameters and a mesopore structure with large pore diameters can be obtained, so that the prepared sound-absorbing material is ensured to have good adsorption and desorption properties, diffusion properties and hydrophobic properties, and the acoustic performance of the loudspeaker is ensured.
Further, the low-carbon liquid in the S2 is furfuryl alcohol.
Further, the acid in the S7 is an HF solution or an HCl solution, and the base in the S7 is NaOH.
Further, the specific step of S7 is:
transferring the molecular sieve-carbon composite into 15% HCl solution, and replacing the HCl solution for 3 times;
filtering the molecular sieve-carbon composite and washing for 3 times by using deionized water to obtain a product;
putting the product into a 50% NaOH solution, stirring for 0.5h at 60 ℃, and replacing the NaOH solution for 3 times;
the alkali-treated product was centrifuged and collected, washed 3 times with deionized water, and dried in air at 40 ℃.
As can be seen from the above description, the sound-absorbing material prepared by the method of first performing acid treatment and then performing alkali treatment has a larger specific surface area, and the sound-absorbing material can improve the stability of the acoustic performance of the speaker after being filled in the speaker.
Further, the specific step of S7 is:
transferring the molecular sieve-carbon composite into an HF solution, and soaking for 1h;
filtering the molecular sieve-carbon composite and washing for 3 times by using deionized water to obtain a product;
the product was placed in 15% HCl solution and stirred at 60 ℃ for 0.5h, HCl solution was changed 3 times;
the acid-treated product was centrifuged and collected, washed 3 times with deionized water, and dried in air at 40 ℃.
The first embodiment of the invention is as follows:
a preparation method of a carbon molecular sieve sound-absorbing material comprises the following steps:
s1: selecting a molecular sieve with the diameter of micropores larger than 2nm as a template agent, wherein the molecular sieve as the template agent is heated at the temperature of 150-450 ℃ and the vacuum degree of a container is 10 -3 ～5×10 -3 Drying and degassing for 6-24 h under the mbar condition, and then cooling to room temperature for later use;
s2: mixing and stirring a certain amount of molecular sieve and a certain amount of furfuryl alcohol in a protective gas atmosphere to obtain a mixture, carrying out vacuum filtration on the mixture, and collecting a solid sample;
s3: cleaning a solid sample for multiple times by adopting mesitylene, drying the solid sample, placing the dried sample in an alumina crucible and transferring the dried sample to a tubular furnace;
s4: vacuumizing the tube furnace, filling the tube furnace with dry argon until the pressure in the tube furnace reaches 1 mbar-1 bar, and keeping the flow rate of the argon at 100 mL/min-300 mL/min;
s5: raising the temperature to 70-120 ℃ at a constant speed, keeping the temperature for 12-36 h, then quickly heating to 600-800 ℃ for carbonization for 1-3 h;
forming mixed gas of low-carbon gas and nitrogen or argon as protective gas, filling the mixed gas into the tubular furnace, and switching the protective gas into dry argon after 1-5 h; wherein, when the solid sample is carbonized at high temperature, other gas micromolecules such as H are generated 2 ，NH 3 (ii) a The dry argon can take away the small molecules, so that the small gas molecules are prevented from blocking the pore channels of the carbon molecular sieve.
S6: heating the molecular sieve-carbon composite to 800-1100 ℃ within 1h, quenching for 2-5 h, cooling overnight, and closing gas;
s7: transferring the molecular sieve-carbon composite into an acid or alkali solution, replacing the acid or alkali solution for 1-3 times, centrifugally collecting the carbon molecular sieve, washing the carbon molecular sieve with deionized water for several times, and drying the carbon molecular sieve in air at 60-100 ℃ to obtain the carbon molecular sieve;
s8: mixing the carbon molecular sieve with a binder to form sound-absorbing particles with the particle size of 200-500 mu m;
the S8 specifically comprises the following steps of mixing a carbon molecular sieve and water according to a ratio of 1: (1-10) in the proportion of 1: (2-5);
mixing a binder with a solid content of 50% and water according to a ratio of 1: (1 to 4) to obtain an aqueous binder dispersion, and preferably, the mixing ratio of 50% of the binder to water is 1: (1.5-3);
mixing the composite molecular sieve powder aqueous dispersion and the binder aqueous dispersion according to the ratio of (2-10): 1 to obtain a mixture, and preferably, the mixing ratio of the composite molecular sieve powder aqueous dispersion to the binder aqueous dispersion is (4.5-9): 1;
the mixture is sprayed and dried in a spray dryer under the spray pressure of 0.02 Mpa-0.1 Mpa and the drying temperature of 80-120 ℃ to form the sound-absorbing particles.
Preferably, the binder is a polyacrylic binder.
Wherein the low-carbon gas in S5 is carbon monoxide, propylene or formaldehyde. The carbon structure which is not bonded can be repaired by adopting low-carbon gas, and a three-dimensional continuous ordered carbon structure is formed as far as possible; and nitrogen is used as protective gas and reacts with the low-carbon gas decomposition product, so that the formation of a three-dimensional carbon structure can be promoted and the production cost is reduced by adopting the mixed gas of the low-carbon gas and the nitrogen.
Optionally, the molecular sieve used as the template in S1 is NaY molecular sieve, BEA, EMT, FAU, IRR or ISV. The structural code of the molecular sieve used as the template agent is shown in detail inhttps://europe.iza-structure.org/IZA-SC/ftc_ table.php。
Optionally, the acid in S7 is HF solution or HCl solution, and the base in S7 is NaOH.
The second embodiment of the invention is as follows:
a preparation method of a carbon molecular sieve sound-absorbing material comprises the following steps:
s1: selecting NaY molecular sieve as template agent, weighing 5g of NaY molecular sieve and placing the NaY molecular sieve into three necksIn a round-bottom flask, a three-neck round-bottom flask is evacuated to 10 ℃ at a temperature of 200 DEG C -3 mbar, drying and degassing for 24h, and then cooling to room temperature for later use; wherein, the silicon-aluminum ratio of the NaY molecular sieve is 2.3.
S2: mixing and stirring the dried NaY molecular sieve and 25mL of 99% furfuryl alcohol in a protective gas atmosphere to obtain a mixture, carrying out vacuum filtration on the mixture, and collecting a solid sample; wherein, the gas in the protective gas atmosphere is nitrogen or helium;
s3: cleaning a solid sample for three times by adopting 97% mesitylene, wherein the dosage of 97% mesitylene is 15mL in each cleaning; carrying out suction filtration drying on the solid sample for 15min, placing the dried sample in an alumina crucible, transferring the dried sample to a quartz tube, and placing the quartz tube in a tube furnace;
s4: vacuumizing the tube furnace, filling the tube furnace with dry argon until the pressure in the tube furnace reaches the room pressure, and keeping the flow rate of the argon at 200mL/min; wherein, chamber pressure herein refers to a standard atmospheric pressure;
s5: heating to 80 ℃ within 10min, wherein furfuryl alcohol starts to polymerize in the heating process, keeping the temperature for 24h to ensure that furfuryl alcohol is completely polymerized, and heating the polymerized furfuryl alcohol to 700 ℃ within 2h for carbonization for 1h;
performing chemical vapor deposition of propylene at 700 ℃, specifically, forming a mixed gas of 7mol% of propylene and argon as a protective gas, filling the mixed gas into a tubular furnace, adjusting the flow rate of the mixed gas to 200mL/min, adjusting the pressure to room pressure for vapor deposition, switching the protective gas to dry argon after deposition for 3h, and keeping the flow rate of the dry argon at 200mL/min;
s6: heating the molecular sieve-carbon composite to 900 ℃ within 1h, quenching for 1h, and performing thermal decomposition on the carbon composite repaired by propylene chemical vapor deposition after furfuryl alcohol polymerization at the high temperature of 900 ℃, so that the generated carbon atoms and polymers thereof take the molecular sieve as a framework to form a three-dimensional continuous carbon tissue; cooling overnight, turning off the gas, and transferring the molecular sieve-carbon composite into 50mL of 50% NaOH solution, and stirring at 60 ℃ for 0.5h;
s7: transferring the molecular sieve-carbon composite into a NaOH solution, replacing the NaOH solution for 3 times, stirring for 0.5h each time, centrifugally collecting the carbon molecular sieve, washing for 3 times by using deionized water, and drying in air at 40 ℃ to obtain the carbon molecular sieve;
s8: mixing a carbon molecular sieve with a binder to form sound-absorbing particles with the particle size of 200-500 mu m;
the S8 specifically comprises the following steps of mixing a carbon molecular sieve and water according to a ratio of 1: (1-10) in the proportion of 1: (2-5);
mixing a binder with a solid content of 50% and water according to a ratio of 1: (1 to 4) to obtain an aqueous binder dispersion, and preferably, the mixing ratio of 50% of the binder to water is 1: (1.5 to 3);
mixing the composite molecular sieve powder aqueous dispersion and the binder aqueous dispersion according to the ratio of (2-10): 1 to obtain a mixture, and preferably, the mixing ratio of the composite molecular sieve powder aqueous dispersion to the binder aqueous dispersion is (4.5-9): 1;
the mixture is sprayed and dried in a spray dryer under the spray pressure of 0.06MPa to 0.08MPa and the drying temperature of 100 ℃ to form the sound-absorbing particles with the particle size of 300 to 450 mu m.
Preferably, the binder is a polyacrylate binder.
EXAMPLE III
In this embodiment, a second processing manner is adopted for S7 on the basis of the second embodiment.
Specifically, the specific step of S7 is:
transferring the molecular sieve-carbon composite into 15% HCl solution, and replacing the HCl solution for 3 times to ensure that all aluminum elements in the molecular sieve-carbon composite are dissolved, wherein the stirring is carried out for 0.5 hour each time;
filtering the molecular sieve-carbon composite and washing for 3 times by using deionized water to obtain a product;
the product was placed in 50mL of 50% NaOH solution and stirred at 60 ℃ for 0.5h, naOH solution was changed 3 times;
and centrifuging and collecting the product after the alkali treatment, washing the product for 3 times by using 50mL of deionized water, and drying the product in air at 40 ℃ to obtain the carbon molecular sieve.
Example four
A preparation method of a carbon molecular sieve sound-absorbing material comprises the following steps:
s1: selecting Na-EMT molecular sieve as template agent, weighing 5g of Na-EMT molecular sieve, placing into a three-neck round-bottom flask, and vacuumizing the three-neck round-bottom flask to 10 ℃ at the temperature of 200 DEG C -3 mbar, drying and degassing for 24h, and then cooling to room temperature for later use; wherein the silica-alumina ratio of the Na-EMT molecular sieve is 1.1.
S2: mixing and stirring the dried Na-EMT molecular sieve and 25mL 99% furfuryl alcohol in a protective gas atmosphere to obtain a mixture, carrying out vacuum filtration on the mixture, and collecting a solid sample;
s3: cleaning a solid sample for three times by adopting 97% mesitylene, wherein the using amount of 97% mesitylene is 15mL in each cleaning; carrying out suction filtration drying on the solid sample for 15min, placing the dried sample in an alumina crucible, transferring the dried sample to a quartz tube, and placing the quartz tube in a tube furnace;
s4: vacuumizing the tubular furnace, filling the tubular furnace with dry argon until the pressure in the tubular furnace reaches room pressure, and keeping the flow rate of the argon at 200mL/min;
s5: heating to 80 ℃ within 10min, wherein furfuryl alcohol starts to polymerize in the heating process, keeping the temperature for 24h to ensure that the furfuryl alcohol is completely polymerized, and heating the polymerized furfuryl alcohol to 700 ℃ within 2h for carbonization for 1h;
performing chemical vapor deposition of propylene at 700 ℃, specifically, forming a mixed gas by 7mol% of propylene and argon as a protective gas, filling the mixed gas into a tubular furnace, adjusting the flow rate of the mixed gas to 200mL/min, adjusting the pressure to room pressure to perform vapor deposition, switching the protective gas to dry argon after deposition for 3h, and keeping the flow rate of the dry argon to 200mL/min;
s6: heating the molecular sieve-carbon composite to 900 ℃ within 1h, quenching for 1h, and performing thermal decomposition on the carbon composite repaired by propylene chemical vapor deposition after furfuryl alcohol polymerization at the high temperature of 900 ℃, so that the generated carbon atoms and polymers thereof take the molecular sieve as a framework to form a three-dimensional continuous carbon tissue; cool overnight, turn off the gas, and transfer the molecular sieve-carbon composite to 50mL50% NaOH solution, stir at 60 ℃ for 0.5h;
s7: transferring the molecular sieve-carbon composite into 50mL 36% HF solution, and soaking for 1h;
filtering the molecular sieve-carbon composite and washing for 3 times by using deionized water to obtain a product;
the product was taken up in 50mL of 15% HCl solution and stirred at 60 ℃ for 0.5h, the HCl solution was changed 3 times;
the acid treated product was centrifuged and collected, washed 3 times with 50mL of deionized water and dried in air at 40 ℃.
S8: mixing the carbon molecular sieve with a binder to form sound-absorbing particles with the particle size of 200-500 mu m;
the S8 specifically comprises the following steps of mixing a carbon molecular sieve and water according to a ratio of 1: (1-10) in the proportion of 1: (2-5);
mixing a binder with a solid content of 50% and water according to a ratio of 1: (1-4) to obtain an aqueous binder dispersion, preferably, the mixing ratio of 50% binder to water is 1: (1.5 to 3);
and (3) mixing the composite molecular sieve powder aqueous dispersion and the binder aqueous dispersion according to the ratio of (2-10): 1 to obtain a mixture, and preferably, the mixing ratio of the composite molecular sieve powder aqueous dispersion to the binder aqueous dispersion is (4.5-9): 1;
the mixture is sprayed and dried in a spray dryer under the spray pressure of 0.06MPa to 0.08MPa and the drying temperature of 100 ℃ to form the sound-absorbing particles with the particle size of 300 to 450 mu m.
Preferably, the binder is a polyacrylate binder.
The specific surface area of the carbon molecular sieves prepared in example three and example four was measured, and the measurement results are shown in table 1.
TABLE 1 determination of specific surface area of carbon molecular sieves in example III and example IV
| S BET | V micro (cm 3 /g) | V meso (cm 3 /g) | V total (cm 3 /g) | |
| EXAMPLE III | 251.0810 | 0.05885 | 0.13863 | 0.19748 |
| Example four | 250.8372 | 0.06654 | 0.14107 | 0.20761 |
The sound-absorbing particles prepared in example two, example three and example four were filled in the rear sound cavities of the respective speakers (the rear sound cavity volume was 0.22cc, abbreviated as 0.22cc, and the sound-absorbing particle filling amount was 0.185 cc), and the resonance frequency F0 and Q value of each speaker were measured, and the results of the measurements are shown in table 2.
Table 2 test result data table before and after three speakers are added to the sound-absorbing particles
Therefore, after the sound absorbing particles prepared in the second embodiment, the third embodiment and the fourth embodiment are filled in the rear sound cavity of the loudspeaker, the resonant frequency F0 and the Q value of the loudspeaker are both reduced, so that the sound absorbing particles prepared in the second embodiment, the third embodiment and the fourth embodiment can reduce the damping of the loudspeaker, improve the low-frequency response of the loudspeaker and improve the low-frequency acoustic performance of the loudspeaker.
In summary, in the preparation method of the carbon molecular sieve sound-absorbing material provided by the invention, in the synthesis process of the mesoporous structure of the carbon molecular sieve, carbon atoms are aggregated into dimers or multimers; the polymers are connected into bonds, so that mesoporous tissues can be formed; the size range of the mesopores is 2 to 50 nanometers (10) -9 Meter), the size of the carbon molecular sieve is larger than that of common air molecules, so that a pore channel is provided for the air molecules to freely enter the carbon molecular sieve, the fast adsorption and desorption and diffusion properties of sound-absorbing materials to the gas in the rear cavity of the loudspeaker are facilitated, the damping of the loudspeaker is reduced, the low-frequency response of the loudspeaker is improved, and the low-frequency acoustic performance of the loudspeaker is improved; in addition, with the sound absorbing material contrast that the molecular sieve made, the sound absorbing material hydrophobicity that the carbon molecular sieve made is more excellent, can effectually avoid making the problem that speaker stability reduces because of excessively adsorbing moisture.
The above description is only an embodiment of the present invention, and not intended to limit the scope of the present invention, and all equivalent changes made by using the contents of the present specification and the drawings, or applied directly or indirectly to the related technical fields, are included in the scope of the present invention.
Claims (7)
1. The preparation method of the carbon molecular sieve sound-absorbing material is characterized by comprising the following steps of:
s1: selecting a molecular sieve with the diameter of a micropore larger than 2nm as a template agent, drying and degassing the molecular sieve for 6-24 h at the temperature of 150-450 ℃ under the condition that a container is in vacuum, and then cooling to room temperature for later use;
s2: mixing and stirring a certain amount of molecular sieve and a certain amount of low-carbon liquid with 1-5 carbon atoms in a protective gas atmosphere to obtain a mixture, carrying out vacuum filtration on the mixture, and collecting a solid sample;
s3: cleaning a solid sample for multiple times by adopting mesitylene, drying the solid sample, placing the dried sample in an alumina crucible and transferring the dried sample to a tubular furnace;
s4: vacuumizing the tube furnace, filling the tube furnace with dry argon until the pressure in the tube furnace reaches 1 mbar-1 bar, and keeping the flow rate of the argon at 100 mL/min-300 mL/min;
s5: raising the temperature to 70-120 ℃ at a constant speed, keeping the temperature for 12-36 h, then quickly heating to 600-800 ℃ for carbonization, wherein the carbonization time is 1-3 h;
forming a mixed gas of a low-carbon gas with 1-5 carbon atoms and nitrogen or argon as a protective gas, filling the mixed gas into the tubular furnace, and switching the protective gas into dry argon after 1-5 hours;
s6: heating the molecular sieve-carbon composite to 800-1100 ℃ within 1h, quenching for 2-5 h, cooling overnight, and closing gas;
s7: transferring the molecular sieve-carbon composite into an acid or alkali solution, replacing the acid or alkali solution for 1-3 times, centrifugally collecting the carbon molecular sieve, washing the carbon molecular sieve with deionized water for at least three times, and drying the carbon molecular sieve in air at 60-100 ℃ to obtain the carbon molecular sieve;
s8: mixing a carbon molecular sieve with a binder to form sound-absorbing particles with the particle size of 200-500 mu m;
the S7 comprises the following specific steps:
transferring the molecular sieve-carbon complex to 15% HCl solution, and replacing the HCl solution 3 times;
filtering the molecular sieve-carbon composite and washing for 3 times by using deionized water to obtain a product;
the product was placed in 50% NaOH solution and stirred at 60 ℃ for 0.5h;
centrifuging and collecting the product after alkali treatment, washing for 3 times by using deionized water, and drying in air at 40 ℃;
or, the specific step of S7 is:
transferring the molecular sieve-carbon composite into an HF solution, and soaking for 1h;
filtering the molecular sieve-carbon composite and washing the molecular sieve-carbon composite for 3 times by using deionized water to obtain a product;
the product was placed in 15% HCl solution and stirred at 60 ℃ for 0.5h;
the acid-treated product was centrifuged and collected, washed 3 times with deionized water, and dried in air at 40 ℃.
2. The method for preparing the carbon molecular sieve sound absorbing material of claim 1, wherein the step S8 comprises the following steps:
mixing a carbon molecular sieve and water according to the weight ratio of 1: (1-10) are mixed into composite molecular sieve powder water dispersion;
mixing a binder with a solid content of 50% and water according to a ratio of 1: (1-4) to obtain a binder water dispersion;
and (3) mixing the composite molecular sieve powder aqueous dispersion and the binder aqueous dispersion according to the ratio of (2-10): 1 to obtain a mixture;
the mixture is sprayed and dried in a spray dryer under the spray pressure of 0.02 Mpa-0.1 Mpa and the drying temperature of 80-120 ℃ to form the sound-absorbing particles.
3. The method for preparing the carbon molecular sieve sound-absorbing material as claimed in claim 1, wherein the binder is one or more of polyacrylic binder, polyacrylate binder, polyvinyl acetate binder, polystyrene binder or polyurethane binder.
4. The method for preparing the carbon molecular sieve sound absorbing material as claimed in claim 1, wherein the degree of vacuum in the S1 is 10 -3 ～5×10 -3 mbar。
5. The method of claim 1, wherein the low carbon gas in S5 is carbon monoxide, propylene or formaldehyde.
6. The method of claim 1, wherein the molecular sieve used as the template in S1 is NaY molecular sieve, BEA, EMT, FAU, IRR or ISV.
7. The method of claim 1, wherein the low carbon liquid in S2 is furfuryl alcohol.
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