TWI705096B - Aerogel particles and manufacturing method thereof - Google Patents

Abstract

The invention relates to an aerogel particles and a manufacturing method thereof. The manufacturing method comprises the steps of (a)adding a methyl group-containing siloxane and a surfactant to water to uniformly mix and hydrolyze to form a mixed aqueous solution; (b) mixing the mixed aqueous solution with 0.1-0.2M ammonia (NH₄OH) in an organic solvent for stirring to form a water-in-oil (w/o) emulsion by emulsion polymerization; and (c) removing the organic solvent and drying the water-in-oil (w/o) emulsion to obtain the aerogel particles. Accordingly, the present invention does not need to undergo a hydrophobization process and a solvent exchange procedure, which saves the cost and time to prepare the aerogel particles.

Description

Aerogel particles and preparation method thereof

The present invention relates to aerogel particles and a preparation method thereof, in particular to a method for preparing aerogels by using methyl-containing silicone compounds as precursors, which can avoid the use of aerogel surface hydroxylation and solvent exchange. The cumbersome steps are to generate aerogel particles in a dispersed phase with low surface tension and adjust their hydrophobicity and hydrophilicity.

Aerogel is a solid with porous microstructure, which has the characteristics of high specific surface area, high porosity, low overall density and low thermal conductivity. These properties make aerogels competitive in heat insulation, sound insulation and energy saving applications.

The aerogel manufacturing process can be divided into three steps, including first preparing the hydrogel by the sol-gel method, curing the gel, and drying. In the common aerogel manufacturing process, the drying method is the supercritical fluid drying method and the atmospheric drying method. The cost of preparing aerogels using the supercritical fluid drying method is high, while the atmospheric drying method is used to prepare aerogels. Although the glue can reduce the cost, the atmospheric drying method to prepare aerogel requires solvent substitution and surface modification steps. The solvent replacement step refers to replacing the water contained in the gel with another solvent with low surface tension to prevent the aerogel pore structure from collapsing due to capillary force during the drying process; the surface modification step is to remove the aerogel surface Hydroxy silylation causes the aerogel to shrink due to drying, and then return to its original shape due to the repulsive force between the alkyl groups on the surface.

For example, the Republic of China Patent Publication No. 1516447 discloses an "aerogel and its manufacturing method". The steps of the manufacturing method are: preparing an aqueous dioxygen Silica sol; disperse the aqueous silica sol in a hydrophobic solvent to form a W/O emulsion; gel the silica sol and convert the W/O emulsion into a gelled dispersion; The water in the gelatinized body is replaced with a solvent with low surface tension; the gelatinized body is treated with a specific hydrophobizing agent; and the substituted solvent is removed; the above-mentioned previous plan is to prepare aerogels under normal pressure to reduced pressure However, after the emulsification polymerization step is completed, a hydrophobization treatment and solvent replacement step are required before drying to obtain aerogel particles, so the preparation steps are more complicated.

The Republic of China Patent Publication No. I561561 discloses an "aerogel particle and its preparation method", which is made by the following steps: mixing a silicone compound with an organic solvent to form a mixed solution; adding an acid The catalyst is added to the mixed solution to carry out the hydrolysis reaction; an alkaline catalyst is added to the mixed solution to carry out the condensation reaction, and a hydrophobic dispersing solvent is added during the condensation reaction and stirred to make the mixed solution congeal during the stirring process Gelation produces a plurality of aerogel particles; although the above-mentioned previous proposal can produce spherical granular aerogel particles with a relatively uniform structure, the hydrolysis reaction uses an acid catalyst. In addition, after the condensation polymerization is completed, another process is required. The hydrophobic modification step includes adding a chlorinated organic molecule to make the chlorinated organic molecule react with a hydroxyl group of the aerogel particles, and the product will be produced as a strong acid waste liquid to make the aerogel particles hydrophobic The drying step can only be carried out after the temperature, so the preparation steps are more complicated and costly.

In this regard, how to develop a better aerogel process is still a direction that researchers in related fields are thinking of.

Today, the inventors have made improvements based on their rich professional knowledge and years of practical experience in view of the fact that the above-mentioned existing aerogel manufacturing process still has many shortcomings in actual implementation and use, and based on this research and development. invention.

The main purpose of the present invention is to provide an aerogel particle and a preparation method thereof, which is a method for preparing aerogel by using a methyl-containing siloxane compound as a precursor, without using The cumbersome steps such as hydroxylation of the aerogel surface and solvent exchange enable the aerogel particles to be formed in a dispersed phase with low surface tension and adjust their hydrophobicity and hydrophilicity.

In order to achieve the above-mentioned implementation objectives, the present invention provides aerogel particles and a preparation method thereof. The preparation method includes: (a) adding 50-70 vol.% (based on the total volume of the mixed aqueous solution) of methyl-containing silicon Oxyane compound (siloxane) and 0.1-0.3 vol.% (based on the total volume of the mixed aqueous solution) surfactant are added to the water and mixed uniformly and undergo a hydrolysis reaction to form a mixed aqueous solution; (b) 12- 16vol.% (based on the total volume of the mixed aqueous solution, ammonia and organic solvent) mixed aqueous solution and 5-6vol.% (based on the total volume of the mixed aqueous solution, ammonia and organic solvent) of 0.1-0.2M ammonia (NH ₄ OH) and the remaining volume percentage of the organic solvent are mixed, and stirred with a stirring speed of 1,000-5,000 rpm to form a water-in-oil (w/o) emulsion; and (c) remove the organic solvent and dry the oil package Water (w/o) type emulsion, for example, dried at 80°C-150°C under normal pressure for 2-6 hours to obtain aerogel particles. The aerogel particles can also be further heated at 400°C-400°C under normal pressure. Heat treatment is performed at 500°C for 2-8 hours to obtain hydrophilic aerogel particles.

In one embodiment of the present invention, the methyl-containing siloxane compound (siloxane) may be selected from methyltrimethoxysilane, methyltriethoxysilane, and dimethyldimethoxysilane. Dimethoxydimethylsilane, dimethyldiethoxylsilane or polydimethylsiloxane. The organic solvent can be selected from alkanes, alcohols, ethers or ketones, such as hexane, Ethanol, methyl ether or acetone, and the surfactant is hexadecyl-trimethyl-ammonium bromide, sodium dodecyl sulfate, sodium dodecyl benzene sulfonate ( Sodium dodecyl benzene sulfonate) or n-hexadecyltrimethylammonium chloride (n-hexadecyltrimethylammonium chloride).

Therefore, the present invention does not need to carry out complicated steps such as hydroxylation of the aerogel surface and solvent exchange, and can prepare aerogel particles with hydrophobicity or different degrees of hydrophilicity, which solves the tedious and time-consuming preparation procedures of the conventional method. The lack of high cost.

a: Hydrolysis reaction

b: emulsion polymerization

c: dry

d: heat treatment

Figure 1: A flow chart of the preparation method of a preferred embodiment of the present invention.

Figure 2: A flow chart of the preparation method of the second preferred embodiment of the present invention.

Figure 3: Scanning electron micrograph of the aerogel particles of the present invention at a magnification of 3,000.

Figure 4: Scanning electron micrograph of the aerogel particles of the present invention at a magnification of 40,000.

Figure 5: Contact angle analysis diagram of the hydrophobic aerogel particles of the present invention.

Figure 6: Contact angle analysis diagram of the hydrophilic aerogel particles of the present invention.

The purpose of the present invention and its structural and functional advantages will be described based on the structure shown in the following drawings and specific embodiments, so that the review committee can have a deeper and specific understanding of the present invention.

An aerogel particle of the present invention and a preparation method thereof. As shown in the first figure, the preparation method includes the following steps: (a) Mix 50-70 vol.% of a methyl-containing siloxane compound (siloxane) with 0.1 -0.3vol.% surfactant is added to water and mixed uniformly and subjected to hydrolysis to form a mixed aqueous solution; (b) 12-16vol.% mixed aqueous solution and 5-6vol.% 0.1-0.2M ammonia water ( NH ₄ OH) and the remaining volume percentage of the organic solvent are mixed, and stirred at a stirring speed of 1,000-5,000 rpm to form a water-in-oil (w/o) emulsion; and (c) remove the organic solvent and The water-in-oil (w/o) emulsion is dried at 80°C-150°C under normal pressure for 2-6 hours to obtain aerogel particles; preferably, the methyl-containing siloxane compound (siloxane) Can be methyltrimethoxysilane, methyltriethoxysilane, dimethoxydimethylsilane, dimethyldiethoxylsilane or polydimethylsilane Polydimethylsiloxane, the organic solvent can be selected from alkanes, alcohols, ethers or ketones, such as hexane, ethanol, methyl ether or acetone, and the surfactant is selected from cetyltrimethyl bromide Ammonium (hexadecyl-trimethyl-ammonium bromide), sodium dodecyl sulfate (sodium dodecyl sulfate), sodium dodecyl benzene sulfonate or hexadecyl trimethyl ammonium chloride (n- hexadecyltrimethylammonium chloride).

In addition, as shown in the second figure, the preparation method may further include a step (d) heat-treating the aerogel particles at 400°C-500°C under normal pressure for 2-8 hours to obtain a hydrophilic aerogel particle.

In addition, the following specific examples can further prove the scope of practical application of the present invention, but it is not intended to limit the scope of the present invention in any form.

In this example, a methyl-containing silicone compound (siloxane) is used as a precursor, and after hydrolysis, it is condensed and polymerized in a w/o emulsion. After drying the w/o emulsion, a hydrophobic aerogel can be directly obtained particle size of about 75-330 μ M, when the hydrophobic airgel particles are further treated by high temperature, can increase its hydrophilicity.

Example one

Add 30ml of precursor dimethyldimethoxysilane, and 0.1g of surfactant cetyltrimethylammonium bromide into 15ml of water, stir well for 20 minutes; then add 20ml of 0.2M ammonia to the aqueous solution as The catalyst for condensation polymerization, after stirring the aqueous solution for several minutes, pour 300 ml of ethanol and stir at 2,500 rpm to form a w/o emulsion by emulsification polymerization. After about 10 minutes, the condensation polymerization reaction makes the dispersed phase gradually transformed into Aerogel particles; after removing the ethanol, dry at 80oC for 2 hours at normal pressure (or for a long time at normal temperature), then dry at 150 After drying at ℃ for 4 hours, hydrophobic aerogel particles can be obtained. A scanning electron microscope (SEM) is used to capture the distribution and appearance of aerogel particles under different magnifications, as shown in the third and fourth pictures. As shown in the figure.

Example two

Add 30 ml of the precursor methyltrimethoxysilane, and 0.15 g of surfactant sodium dodecylbenzene sulfonate into 30 ml of water and stir well for 20 minutes; then add 20 ml of 0.2M ammonia to the aqueous solution for condensation polymerization The catalyst of the reaction, after stirring the aqueous solution for several minutes, pour in 300 ml of acetone and stir at 2,500 rpm to form a w/o emulsion by emulsification polymerization. After about 10 minutes, the condensation polymerization reaction gradually transforms the dispersed phase into vapor condensation Gel particles: After removing the acetone, dry at 80°C for 2 hours under normal pressure (or for a long time at normal temperature), and then dry at 150°C for 4 hours to obtain hydrophobic aerogel particles.

Example three

Add 30ml of precursor polydimethylsiloxane, and 0.1g of surfactant cetyltrimethylammonium chloride into 20ml of water, stir well for 20 minutes; then add 20ml of 0.1M ammonia to the aqueous solution As a catalyst for condensation polymerization, after stirring the aqueous solution for several minutes, pour 300ml of n-hexane and stir at 2,500rpm to form a w/o emulsion by emulsification polymerization. After about 10 minutes, the condensation polymerization reaction makes the dispersed phase gradually Transform into aerogel particles; after removing n-hexane, dry at 80°C under normal pressure for 2 hours (or for a long time at normal temperature), and then dry at 150°C for 4 hours to obtain hydrophobic aerogel Glue particles.

Example four

Add 30 ml of the precursor dimethyl diethoxysilane, and 0.15 g of surfactant sodium lauryl sulfate into 25 ml of water, and stir well for 20 minutes; then add 20 ml of 0.2M ammonia to the aqueous solution for condensation polymerization The catalyst for the reaction, after stirring the aqueous solution for several minutes, pour 300 ml of methyl ether and stir at 2,500 rpm Mix and emulsify polymerization to form a w/o emulsion. After about 10 minutes, condensation polymerization will gradually transform the dispersed phase into aerogel particles; after removing the methyl ether, dry at 80°C for 2 hours under normal pressure (or Dry for a long time at room temperature), and then dry at 150°C for 4 hours to obtain hydrophobic aerogel particles.

The hydrophobic aerogel particles were subjected to multiple analyses, including the use of a contact angle measuring instrument to analyze the contact angle values of the hydrophobic aerogel particles of the present invention. The results are shown in Figure 5 and Table 1, which has a bulk density (bulk density). ) Is 0.037g/cm ³ , the specific surface area is 546.83m ² /g, the porosity is 90.56%, the particle size is about 75-330μm, and the thermal conductivity is 0.035W/m. K, and the contact angle is 145 degrees.

Example five

The hydrophobic aerogel obtained by the preparation method of Example 1 is then heat-treated at 400°C and 450°C for 2 hours respectively, and aerogel particles with different degrees of hydrophilicity can be obtained. Numerical analysis of the contact angle of the obtained hydrophilic aerogel particles showed that it was 26.08 degrees.

As can be seen from the above implementation description, compared with the prior art, the present invention has the following advantages:

1. In the present invention, the hydrolyzed silicone compound aqueous solution is mixed with an organic solvent to form a w/o type emulsion and carry out emulsification polymerization. After the emulsification polymerization is completed, there is no need to go through surface treatment (such as surface hydroxylation) or add hydrophobic dispersion The solvent modifies the surface to hydrophobicity, and can be dried to obtain hydrophobic aerogel particles. Therefore, the preparation method of the present invention shortens the manufacturing process and reduces the preparation cost.

2. The preparation method of the present invention does not need to use acid catalysts and chlorinated organic molecules for hydrolysis reaction and modification, so it can avoid the generation of strong acid waste liquid.

3. The present invention can further adjust the degree of hydrophilicity of aerogel particles by heat treatment to produce aerogel particles with different characteristics, which is more convenient for industrial use.

In summary, the aerogel particles of the present invention and the preparation method thereof can indeed achieve the expected use effects through the above-disclosed embodiments, and they are in compliance with the provisions and requirements of the patent law. If you file an application for a patent for invention in accordance with the law, you are kindly requested to review it and grant a quasi-patent.

However, the above-mentioned illustrations and descriptions are only preferred embodiments of the present invention, and are not intended to limit the scope of protection of the present invention. Those who are familiar with the art will do other things based on the characteristic scope of the present invention. Equivalent changes or modifications should be regarded as not departing from the design scope of the present invention.

a: Hydrolysis reaction

b: emulsion polymerization

c: dry

Claims (8)

A method for preparing aerogel particles, comprising the following steps: (a) adding 50-70vol.% of methyl-containing silicone compound (siloxane) and 0.1-0.3vol.% of surfactant into water, mixing uniformly and Perform a hydrolysis reaction to form a mixed aqueous solution; (b) mix 12-16vol.% of the mixed aqueous solution with 5-6vol.% of 0.1-0.2M ammonia (NH ₄ OH) and the remaining volume percentage of organic solvent Stirring to form a water-in-oil (w/o) emulsion for emulsion polymerization; and (c) removing the organic solvent and drying the water-in-oil (w/o) emulsion to obtain aerogel particles. The method for preparing aerogel particles according to claim 1, wherein the methyl-containing silicone compound (siloxane) is selected from methyltrimethoxysilane and methyltriethoxysilane , Dimethyldimethoxysilane (dimethoxydimethylsilane), dimethyldiethoxylsilane (dimethyldiethoxylsilane) or polydimethylsiloxane (polydimethylsiloxane), the organic solvent is selected from alkanes, alcohols, ethers Or ketones, and the surfactant is selected from hexadecyl-trimethyl-ammonium bromide, sodium dodecyl sulfate, sodium dodecyl benzene sulfonate ( sodium dodecyl benzene sulfonate) or n-hexadecyltrimethylammonium chloride. The method for preparing aerogel particles according to claim 1, wherein the stirring speed of the step (b) is 1,000-5,000 rpm, and the step (c) is dried at 80°C-150°C under normal pressure 2- 6 hours. The method for preparing aerogel particles according to claim 3, further comprising a step (d) heat-treating the aerogel particles at 400°C-500°C under normal pressure for 2-8 hours to obtain hydrophilic gas Gel particles. An aerogel particle is prepared through the following steps: (a) 50-70vol.% methyl-containing silicone compound (siloxane) and 0.1-0.3vol.% surfactant are added to water and mixed uniformly. Perform a hydrolysis reaction to form a mixed aqueous solution; (b) mix 12-16vol.% of the mixed aqueous solution with 5-6vol.% of 0.1-0.2M ammonia (NH ₄ OH) and the remaining volume percentage of organic solvent Stirring to form a water-in-oil (w/o) emulsion for emulsion polymerization; and (c) removing the organic solvent and drying the water-in-oil (w/o) emulsion to obtain aerogel particles. The aerogel particles according to claim 5, wherein the methyl-containing siloxane compound (siloxane) is selected from methyltrimethoxysilane, methyltriethoxysilane, two Methyldimethoxysilane (dimethoxydimethylsilane), dimethyldiethoxylsilane (dimethyldiethoxylsilane) or polydimethylsiloxane (polydimethylsiloxane), the organic solvent is selected from alkanes, alcohols, ethers or ketones, and the surfactant It is selected from hexadecyl-trimethyl-ammonium bromide, sodium dodecyl sulfate, sodium dodecyl benzene sulfonate or hexadecane N-hexadecyltrimethylammonium chloride (n-hexadecyltrimethylammonium chloride). The aerogel particles according to claim 5, wherein the stirring speed of the step (b) is 1,000-5,000 rpm, and the step (c) is dried at 80°C-150°C for 2-6 hours under normal pressure. The aerogel particles according to claim 7, wherein the aerogel particles are further subjected to heat treatment at 400° C.-500° C. under normal pressure for 2-8 hours to obtain hydrophilic aerogel particles.

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