Preparation method of uniform micron-sized silicon dioxide microspheres

Abstract

The invention discloses a preparation method of uniform micron-sized silicon dioxide microspheres, and particularly relates to the technical field of textile, and the preparation method comprises the following steps: S1, preparing a silicon dioxide microsphere dispersion liquid by adopting a stber method; s2, centrifuging, washing and freeze-drying the silicon dioxide microsphere dispersion liquid to obtain submicron silicon dioxide seed microspheres; s3, a certain amount of ethyl alcohol is added into a round-bottom flask, a certain amount of silicon dioxide seed microspheres are taken and dispersed in the ethyl alcohol, dispersion liquid a is obtained and subjected to ultrasonic oscillation for 1 h, and then a certain amount of ammonia water and water are added to prepare dispersion liquid b; the tetraethoxysilane is dropwise added at a constant speed, secondary nucleation is avoided, large-particle-size silicon dioxide microspheres with the uniform particle size can be formed, the preparation steps are simple and easy to operate, the seed growth time is only 3 hours, the reaction time is greatly shortened compared with the reaction time of 10 hours or above in a traditional seed growth method, and the preparation method is suitable for large-particle-size silicon dioxide microspheres with the uniform particle size and suitable for large-particle-size silicon dioxide microspheres with the uniform particle size. According to the method, the process temperature is close to the room temperature, and more energy is saved.

Description

Technical Field

[0001] The invention relates to the field of textile technology, and more particularly to a method for preparing uniform micron-sized silicon dioxide microspheres. Background Art

[0002] Silica (SiO2) is an important inorganic material and is widely used in electronics, coatings, plastics, medicine and other fields. Its unique physical and chemical properties make uniform silica microspheres of great value in many high-performance applications. Silica microspheres of different particle sizes have different applications: 150-500nm silica microspheres can be used to prepare structural color materials by self-assembly; 400-700nm submicron silica can be used as chromatographic materials in the medical field; 500-1000nm silica particles are grafted with new groups on their surfaces to give them hydrophilic, hydrophobic, temperature-sensitive, pH-sensitive and other properties; 1000-1500nm silica microspheres can be modified to give polymers better mechanical properties; 2000-5000nm silica microspheres can be self-assembled to prepare photonic crystal infrared stealth materials.

[0003] The silica microspheres currently used are mainly prepared by chemical synthesis methods. The main synthesis methods include reverse microemulsion method, precipitation method, sol-gel method, seed growth method, etc. These methods have their own advantages and disadvantages, but the following problems are common: Uneven particle size: Many existing methods make it difficult to control the particle size and morphology of generated microspheres, resulting in unstable product performance.

[0004] High production costs: Complex process flow and equipment requirements make large-scale production challenging.

[0005] Environmental impact: Certain preparation processes may produce harmful by-products that may pollute the environment.

[0006] With the advancement of science and technology, the demand for high-performance materials in various industries is increasing. Uniform micron-sized silica microspheres have gradually attracted attention due to their superior fluidity, filling properties and surface modification capabilities. For example, in the coatings and plastics industries, uniform micron-sized silica can significantly improve the strength and wear resistance of products. In addition, with increasingly stringent environmental regulations, the development of low-environmental-impact preparation processes has also become an important direction for the development of the industry.

[0007] Therefore, there is an urgent need for a new preparation method that can efficiently and economically obtain uniform micron-sized silica microspheres to meet the market demand for high-performance materials and reduce the impact of the production process on the environment. Summary of the invention

[0008] In order to overcome the above-mentioned defects of the prior art, an embodiment of the present invention provides a method for preparing uniform micron-sized silica microspheres. The present invention first prepares submicron silica microspheres with uniform particle size as seeds, and then disperses the seeds in a solution and re-grows them. The prepared large-sized silica microspheres with a particle size range of 1000-4000nm have the characteristic of uniform particle size. In the present invention, the prepared silica microspheres are used as seeds, and a method of adding tetraethyl orthosilicate at a uniform speed is adopted. The particle size is monitored during the dropwise addition process, so that silica microspheres with a target particle size can be prepared, and the controllability of the particle size is achieved. In the present invention, the tetraethyl orthosilicate is added by dropwise addition at a uniform speed, which avoids secondary nucleation, so that the formation of large-sized silica microspheres with uniform particle size can be ensured. The preparation steps of the present invention are simple and easy to operate, and the seed growth time is only 3 hours, which is greatly reduced compared with the reaction time of more than 10 hours in the traditional seed growth method. In the method of the present invention, the process temperature is close to room temperature, which is more energy-efficient, so as to solve the problems raised in the above-mentioned background technology.

[0009] To achieve the above object, the present invention provides the following technical solution: a method for preparing uniform micron-sized silica microspheres, comprising the following steps: S1: Preparation of silica microsphere dispersion by Stöber method; S2: centrifuging, washing, and freeze-drying the silica microsphere dispersion to obtain submicron silica seed microspheres; S3: Add a certain amount of ethanol to a round-bottom flask, take a certain amount of the silica seed microspheres and disperse them therein to obtain a dispersion a, ultrasonically vibrate for 1 hour, and then add a certain amount of ammonia water and water to prepare a dispersion b, wherein the volume fractions of ethanol, ammonia water and water in the dispersion b are 78%-90%, 7-16% and 3-6% respectively, and the mass of silica accounts for 0.6%-1.2% of the total mass of the solvent; S4: placing the dispersion liquid b in a magnetic stirrer at 30° C.-55° C., adding 5%-11% of ethyl orthosilicate to the total volume of the solvent at a certain rate after 10 minutes, taking out a small amount of the reaction liquid from the round-bottom flask every 5-30 minutes to test the particle size until the target particle size is obtained, terminating the reaction, and obtaining a silicon dioxide dispersion liquid c; S5: centrifuging, washing and freeze-drying the silica dispersion c to obtain white micron-sized silica microspheres, which are uniform in size and have a particle size of 1-4 um.

[0010] In a preferred embodiment, the particle size of the submicron silica seed microspheres in step S2 is in the range of 500nm-1000nm.

[0011] In a preferred embodiment, the specific steps of preparing the silica microsphere dispersion by the Stöber method in step S1 are: adding ethanol, ammonia water, and water with mass fractions of 78%-90%, 16%-7%, and 6%-3% respectively into a round-bottom flask in order, placing it in a magnetic stirrer at a temperature of 30°C-55°C, stirring until the temperature is stable, adding tetraethyl orthosilicate, and continuing the reaction for 2h, wherein the total mass fraction of ethanol, ammonia water, and water is 100%, and the amount of tetraethyl orthosilicate accounts for 11%-5% of the total volume of the solvent.

[0012] In a preferred embodiment, the volumes of ethanol, ammonia water and water in the dispersion liquid b in step S3 are 40 ml, 8 ml and 3 ml respectively, and the mass of silicon dioxide is 0.618 g.

[0013] In a preferred embodiment, the dropping speed of ethyl orthosilicate in step S4 is 12 ml / h.

[0014] In a preferred embodiment, in step S4, 20 μl of liquid is taken out from the round-bottom flask at each time interval, which is dispersed in 1.5 ml of ethanol solution and then the particle size is tested.

[0015] In a preferred embodiment, the steps of centrifugation, washing and freeze-drying in steps S2 and S5 are: centrifugation-water washing-centrifugation-ethanol washing-centrifugation-ethanol washing-centrifugation-freeze-drying.

[0016] In a preferred embodiment, the centrifugal speed in step S5 is 2500 rpm.

[0017] Technical effects and advantages of the present invention: The present invention adopts the Stöber method to prepare a silica microsphere dispersion liquid, centrifuges, washes and freeze-dries the silica microsphere dispersion liquid to obtain submicron silica seed microspheres, adds a certain amount of ethanol into a round-bottom flask, takes a certain amount of the silica seed microspheres and disperses them therein to obtain a dispersion liquid a, performs ultrasonic vibration for 1 hour, and then adds a certain amount of ammonia water and water to prepare a dispersion liquid b, wherein the volume fractions of ethanol, ammonia water and water in the dispersion liquid b are 78%-90%, 7-16% and 3-6% respectively, and the mass fractions of the silica mass solvent are 0.6%-1% of the total mass. .2%, placing the dispersion b in a magnetic stirrer at 30°C-55°C, adding 5%-11% of ethyl orthosilicate to the total volume of the solvent at a certain rate after 10 minutes, taking out a small amount of the reaction liquid from the round-bottom flask every 5-30 minutes to test the particle size until the target particle size is produced, terminating the reaction, and obtaining a silica dispersion c, centrifuging, washing, and freeze-drying the silica dispersion c to obtain white micron-sized silica microspheres, which are uniform in size and have a particle size of 1-4um. The present invention first prepares submicron silica microspheres with uniform particle size as seeds, and then disperses the seeds in a solution to grow again. The prepared particle size ranges from 1000 to 4000. The large-sized silica microspheres of nm have the characteristic of uniform particle size. In the present invention, the prepared silica microspheres are used as seeds, and the method of adding ethyl orthosilicate at a uniform speed is adopted. The particle size is monitored during the dropping process, so that silica microspheres with a target particle size can be prepared and the controllability of the particle size is achieved. The ethyl orthosilicate is added by dropping at a uniform speed in the present invention, which avoids secondary nucleation, so that the formation of large-sized silica microspheres with uniform particle size can be ensured. The preparation steps of the present invention are simple and easy to operate, and the seed growth time is only 3 hours, which is greatly reduced compared with the reaction time of more than 10 hours in the traditional seed growth method. In the method of the present invention, the process temperature is close to room temperature, which is more energy-saving. DETAILED DESCRIPTION

[0018] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0019] Example 1 The present invention provides a method for preparing uniform micron-sized silica microspheres, comprising the following steps: S1: Preparation of silica microsphere dispersion by Stöber method; S2: centrifuging, washing, and freeze-drying the silica microsphere dispersion to obtain submicron silica seed microspheres; S3: Add a certain amount of ethanol to a round-bottom flask, take a certain amount of the silica seed microspheres and disperse them therein to obtain a dispersion a, ultrasonically vibrate for 1 hour, and then add a certain amount of ammonia water and water to prepare a dispersion b, wherein the volume fractions of ethanol, ammonia water and water in the dispersion b are 78%-90%, 7-16% and 3-6% respectively, and the mass of silica accounts for 0.6%-1.2% of the total mass of the solvent; S4: placing the dispersion liquid b in a magnetic stirrer at 30° C.-55° C., adding 5%-11% of ethyl orthosilicate to the total volume of the solvent at a certain rate after 10 minutes, taking out a small amount of the reaction liquid from the round-bottom flask every 5-30 minutes to test the particle size until the target particle size is obtained, terminating the reaction, and obtaining a silicon dioxide dispersion liquid c; S5: centrifuging, washing and freeze-drying the silica dispersion c to obtain white micron-sized silica microspheres, which are uniform in size and have a particle size of 1-4 um.

[0020] The particle size range of the submicron silica seed microspheres in step S2 is 500nm-1000nm.

[0021] The specific steps of preparing the silica microsphere dispersion liquid by the Stöber method in step S1 are as follows: adding ethanol, ammonia water and water with mass fractions of 78%-90%, 16%-7% and 6%-3% respectively into a round-bottom flask in order, placing it in a magnetic stirrer at a temperature of 30°C-55°C, stirring until the temperature is stable, adding tetraethyl orthosilicate, and continuing the reaction for 2 hours, wherein the total mass fraction of ethanol, ammonia water and water is 100%, and the amount of tetraethyl orthosilicate used accounts for 11%-5% of the total volume of the solvent.

[0022] In the step S3, the volumes of ethanol, ammonia water and water in the dispersion liquid b are 40 ml, 8 ml and 3 ml respectively, and the mass of silicon dioxide is 0.618 g.

[0023] The dropping speed of ethyl orthosilicate in step S4 is 12 ml / h.

[0024] In step S4, 20 μl of the liquid was taken out from the round-bottom flask at each time interval, dispersed in 1.5 ml of ethanol solution and then the particle size was tested.

[0025] The steps of centrifugation, washing and freeze-drying in steps S2 and S5 are: centrifugation-water washing-centrifugation-ethanol washing-centrifugation-ethanol washing-centrifugation-freeze-drying.

[0026] The centrifugal speed in step S5 is 2500 rpm.

[0027] Example 1 A method for preparing micron-sized silica microspheres comprises the following steps: S1, add 40 ml of ethanol, 8 ml of ammonia water, and 3 ml of water into a round-bottom flask in order, place the round-bottom flask in a magnetic stirrer at 30°C, stir for 10 min, add tetraethyl orthosilicate after the temperature stabilizes, and fully react for 2 h to obtain a silica microsphere dispersion; S2, the silica microsphere dispersion is subjected to centrifugation-water washing-centrifugation-ethanol washing-centrifugation-freeze drying to obtain silica seed microspheres. 0.002 g of silica seed microspheres are taken and dispersed in 1.5 ml of ethanol solution, and the particle size is measured to be 600 nm, and PDI=0.03.

[0028] S3, add 40 ml of ethanol to a round-bottom flask, and then disperse 0.618 g of silica seed microspheres therein to obtain dispersion a, ultrasonically vibrate for 1 h, and then add 8 ml of ammonia water and 3 ml of water to prepare dispersion b; S4, placing the dispersion b in a magnetic stirrer at 30°C and 600 rpm, adding tetraethyl orthosilicate at a rate of 12 ml / h after 10 minutes, taking out a certain amount of the reaction liquid from the round-bottom flask every 5 minutes to test the particle size until the particle size is 1450 nm, stopping the addition of tetraethyl orthosilicate, and continuing the reaction for 3 hours to obtain a micron-sized silica dispersion c; S5, centrifuging, washing and freeze-drying the silica dispersion c to obtain micron-sized silica powder. The size of the obtained silica powder microspheres was 1450 nm using a laser particle size analyzer; the polymer dispersibility index (PDI) = 0.06, indicating that the molecular weight distribution was relatively uniform.

[0029] Example 2 A method for preparing micron-sized silica microspheres comprises the following steps: S1, same as S1 in Example 1; S2, the silica microsphere dispersion is subjected to centrifugation-water washing-centrifugation-ethanol washing-centrifugation-freeze drying to obtain silica seed microspheres. 0.002 g of silica seed microspheres are taken and dispersed in 1.5 ml of ethanol solution, and the particle size is measured to be 700 nm; S3, same as S3 of Example 1; S4, placing the dispersion b in a magnetic stirrer at 30°C and 600 rpm, adding tetraethyl orthosilicate at a rate of 12 ml / h after 10 minutes, taking out a certain amount of the reaction liquid from the round-bottom flask every 5 minutes to test the particle size, until the particle size is 1600 nm, stopping the addition of tetraethyl orthosilicate, and continuing the reaction for 3 hours to obtain a micron-sized silica dispersion c; S5, centrifuging, washing and freeze-drying the silica dispersion c to obtain micron-sized silica microspheres. The size of the obtained silica powder microspheres was measured by a laser particle size analyzer to be 1600 nm, with a PDI of 0.07.

[0030] Example 3 A method for preparing micron-sized silica microspheres comprises the following steps: S1-S3 are the same as S1-S3 of Example 2.

[0031] S4. Place the dispersion b in a magnetic stirrer at 30°C and 600 rpm. After 10 minutes, add tetraethyl orthosilicate at a rate of 12 ml / h. Take out a certain amount of the reaction solution from the round-bottom flask every 5 minutes to test the particle size until the particle size is 4000 nm. Stop adding tetraethyl orthosilicate and continue the reaction for 3 hours to obtain a micron-sized silica dispersion c. S5. Centrifuge, wash and freeze-dry the silica dispersion c to obtain micron-sized silica powder. The size of the obtained silica microspheres measured by a laser particle size analyzer is 4000 nm, and PDI = 0.09.

[0032] The present invention adopts the Stöber method to prepare a silica microsphere dispersion liquid, centrifuges, washes and freeze-dries the silica microsphere dispersion liquid to obtain submicron silica seed microspheres, adds a certain amount of ethanol into a round-bottom flask, takes a certain amount of the silica seed microspheres and disperses them therein to obtain a dispersion liquid a, performs ultrasonic vibration for 1 hour, and then adds a certain amount of ammonia water and water to prepare a dispersion liquid b, wherein the volume fractions of ethanol, ammonia water and water in the dispersion liquid b are 78%-90%, 7-16% and 3-6% respectively, and the mass fractions of the silica mass solvent are 0.6%-1% of the total mass. .2%, placing the dispersion b in a magnetic stirrer at 30°C-55°C, adding 5%-11% of ethyl orthosilicate to the total volume of the solvent at a certain rate after 10 minutes, taking out a small amount of the reaction liquid from the round-bottom flask every 5-30 minutes to test the particle size until the target particle size is produced, terminating the reaction, and obtaining a silica dispersion c, centrifuging, washing, and freeze-drying the silica dispersion c to obtain white micron-sized silica microspheres, which are uniform in size and have a particle size of 1-4um. The present invention first prepares submicron silica microspheres with uniform particle size as seeds, and then disperses the seeds in a solution to grow again. The prepared particle size ranges from 1000 to 4000. The large-sized silica microspheres of nm have the characteristic of uniform particle size. In the present invention, the prepared silica microspheres are used as seeds, and the method of adding ethyl orthosilicate at a uniform speed is adopted. The particle size is monitored during the dropping process, so that silica microspheres with a target particle size can be prepared and the controllability of the particle size is achieved. The ethyl orthosilicate is added by dropping at a uniform speed in the present invention, which avoids secondary nucleation, so that the formation of large-sized silica microspheres with uniform particle size can be ensured. The preparation steps of the present invention are simple and easy to operate, and the seed growth time is only 3 hours, which is greatly reduced compared with the reaction time of more than 10 hours in the traditional seed growth method. In the method of the present invention, the process temperature is close to room temperature, which is more energy-saving.

[0033] Finally: The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for preparing uniform micron-sized silica microspheres, characterized in that: The following steps are involved: S1: Preparation of silica microsphere dispersion by Stöber method; S2: centrifuging, washing, and freeze-drying the silica microsphere dispersion to obtain submicron silica seed microspheres; S3: Add a certain amount of ethanol to a round-bottom flask, take a certain amount of the silica seed microspheres and disperse them therein to obtain a dispersion a, ultrasonically vibrate for 1 hour, and then add a certain amount of ammonia water and water to prepare a dispersion b, wherein the volume fractions of ethanol, ammonia water and water in the dispersion b are 78%-90%, 7-16% and 3-6% respectively, and the mass of silica accounts for 0.6%-1.2% of the total mass of the solvent; S4: placing the dispersion liquid b in a magnetic stirrer at 30° C.-55° C., adding 5%-11% of ethyl orthosilicate to the total volume of the solvent at a certain rate after 10 minutes, taking out a small amount of the reaction liquid from the round-bottom flask every 5-30 minutes to test the particle size until the target particle size is obtained, terminating the reaction, and obtaining a silicon dioxide dispersion liquid c; S5: centrifuging, washing and freeze-drying the silica dispersion c to obtain white micron-sized silica microspheres, which are uniform in size and have a particle size of 1-4 um.

2. The method for preparing uniform micron-sized silica microspheres according to claim 1, characterized in that: The particle size range of the submicron silica seed microspheres in step S2 is 500nm-1000nm.

3. The method for preparing uniform micron-sized silica microspheres according to claim 1, characterized in that: The specific steps of preparing the silica microsphere dispersion liquid by the Stöber method in step S1 are as follows: adding ethanol, ammonia water and water with mass fractions of 78%-90%, 16%-7% and 6%-3% respectively into a round-bottom flask in order, placing it in a magnetic stirrer at a temperature of 30°C-55°C, stirring until the temperature is stable, adding tetraethyl orthosilicate, and continuing the reaction for 2 hours, wherein the total mass fraction of ethanol, ammonia water and water is 100%, and the amount of tetraethyl orthosilicate used accounts for 11%-5% of the total volume of the solvent.

4. The method for preparing uniform micron-sized silica microspheres according to claim 1, characterized in that: In the step S3, the volumes of ethanol, ammonia water and water in the dispersion b are 40 ml, 8 ml and 3 ml respectively, and the mass of silicon dioxide is 618 g.

5. The method for preparing uniform micron-sized silica microspheres according to claim 1, characterized in that: The dropping speed of ethyl orthosilicate in step S4 is 12 ml / h.

6. The method for preparing uniform micron-sized silica microspheres according to claim 1, characterized in that: In step S4, 20 μl of liquid is taken out from the round-bottom flask at each time interval, dispersed in 5 ml of ethanol solution and then the particle size is tested.

7. The method for preparing uniform micron-sized silica microspheres according to claim 1, characterized in that: The steps of centrifugation, washing and freeze-drying in steps S2 and S5 are: centrifugation-water washing-centrifugation-ethanol washing-centrifugation-ethanol washing-centrifugation-freeze-drying.

8. The method for preparing uniform micron-sized silica microspheres according to claim 1, characterized in that: The centrifugal speed in step S5 is 2500 rpm.