A method for preparing a solvent-based silica sol

Abstract

The application discloses a preparation method of a solvent type silica sol, which comprises the following steps: (1) a certain amount of silica sol is placed into a drying device and dried into a solid; (2) the silica solid obtained in the step (1) is dispersed in a non-polar solvent, and a silane coupling agent is added for modification; (3) the liquid-solid mixture obtained in the step (2) is ground for a period of time; and (4) insoluble substances in the liquid obtained in the step (3) are filtered out, so as to obtain the required solvent type silica sol. The preparation method of the solvent type silica sol is simple in process, energy-saving and environment-friendly, and the solvent type silica sol prepared by the method has good dispersibility and no agglomeration phenomenon.

Description

Technical Field

[0001] This invention relates to the field of nano-silica sol technology, and in particular to a method for preparing solvent-based silica sol. Background Technology

[0002] Silica sol is a dispersion of nano-sized silica particles in water or solvent. Silica sol can be mixed with various organic polymers, forming Si-O bonds as the solvent evaporates, resulting in strong rigidity and binding ability. Organic solvent-dispersed silica sol can be used as a microfiller, resin additive, and coating for hard coatings or films formed on surfaces.

[0003] In coatings, silica can be used as a main component of the coating or as a filler, existing as SiO2 particles to contribute to the formation of a rough texture. Silica coatings possess advantages such as heat resistance, corrosion resistance, high impact toughness, and ease of cleaning, making them widely applicable in industrial production.

[0004] Chinese patent CN1699166A discloses a general method for preparing an organic solvent silica sol with a boiling point higher than water using sodium silicate as a raw material. This method uses sodium silicate as a raw material, first employing an ion exchange method by adding a stabilizer that acts as a capping agent to prevent gelation during the polymerization of H4SiO4, thus obtaining a stable SiO2 hydrosol. After the hydrosol is prepared, it is mixed with a certain volume of a high-boiling-point organic solvent, and a "solvent replacement method" is used. This method utilizes the difference in boiling points between water and the added solvent to completely replace the water in the mixture, thereby obtaining the high-boiling-point organic solvent SiO2 sol. This patent uses a high-temperature solvent replacement method, which is complex and energy-intensive.

[0005] The present invention was developed to address the aforementioned problems. Summary of the Invention

[0006] The purpose of this invention is to provide a method for preparing solvent-based silica sol, which is simple, does not require a large amount of solvent replacement, and has low energy consumption.

[0007] Based on the above problems, the technical solution provided by the present invention is as follows:

[0008] A method for preparing solvent-based silica sol includes the following steps:

[0009] (1) Take a certain amount of silica sol and put it into a drying device to dry it into a solid;

[0010] (2) Disperse the silica solid obtained in step (1) in a non-polar solvent and add a silane coupling agent for modification;

[0011] (3) Grind the liquid-solid mixture obtained in step (2) for a period of time;

[0012] (4) Filter out the insoluble matter in the liquid obtained in step (3) to obtain the desired solvent-based silica sol.

[0013] In some of these embodiments, the drying temperature in step (1) is 80–150°C.

[0014] In some of these embodiments, the water content of the solid obtained in step (1) is less than 0.5%.

[0015] In some of these embodiments, the silica sol in step (1) is a water-soluble or alcohol-soluble silica sol with a particle size of 10–100 nm.

[0016] In some of these embodiments, the drying method in step 1) is ordinary drying, vacuum drying, or freeze drying, and the drying equipment is an oven or a microwave drying oven.

[0017] In some of these embodiments, the mass ratio of the nonpolar solvent to the solid obtained in step (1) is 1:1 to 9:1.

[0018] In some embodiments, the amount of silane coupling agent in step (2) is 1% to 5% of the amount of solid material obtained in step (1), and is specifically selected according to the particle size of silica sol. The content of silane coupling agent is reduced as the particle size increases.

[0019] In some of these embodiments, the nonpolar solvent in step (2) is one of cyclohexane, acetone, xylene, n-heptane, or paraffin oil.

[0020] In some of these embodiments, the silane coupling agent in step (2) is one of methyltrimethoxysilane, phenyltrimethoxysilane, methyltriethoxysilane, propyltrimethoxysilane, dimethyldimethoxysilane, and dimethyldiethoxysilane.

[0021] In some of these embodiments, the grinding time in step (3) is 12 to 24 hours.

[0022] In some of these embodiments, the filtration method in step (4) is one of vacuum filtration, pressure filtration, or centrifugation.

[0023] Compared with the prior art, the advantages of the present invention are:

[0024] 1. The process is simple. The silica sol is dried into a solid and mixed with a non-polar solvent before adding a silane coupling agent for modification. This reduces the influence of hydroxyl groups on the silane coupling agent, prevents the hydrolysis and condensation of the silane coupling agent itself, and ensures that the silane coupling agent uniformly coats the silica molecules, thus ensuring good dispersion of the silica particles. This eliminates the need to waste a large amount of solvent for replacement and reduces environmental pressure.

[0025] 2. The silica sol prepared by this method is solvent-based, which is different from conventional aqueous silica sol. It is easier to mix with organic matter in coatings, less prone to flocculation, and has a wide range of applications.

[0026] 3. The particle size of the silica sol obtained by this method can be adjusted according to the particle size of the original silica sol. The particle size is 10-100 nm, and the solid content is adjustable in the range of 8%-40%.

[0027] 4. With high purity raw materials, no metal impurities are introduced during the preparation process, and the silica sol obtained is free of fluorine, resulting in high purity. Attached Figure Description

[0028] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. The accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0029] Figure 1 These are TEM images of the original silica sol used in Example 1;

[0030] Figure 2 These are TEM images of the xylene-type silica sol prepared in Example 1;

[0031] Figure 3 These are TEM images of the original silica sol used in Example 2;

[0032] Figure 4 These are TEM images of the acetone-type silica sol prepared in Example 2;

[0033] Figure 5 These are TEM images of the original silica sol used in Example 3;

[0034] Figure 6 These are TEM images of the cyclohexane-type silica sol prepared in Example 3;

[0035] Figure 7 This is a TEM image of the original silica sol used in Example 4;

[0036] Figure 8These are TEM images of the n-heptane-type silica sol prepared in Example 4;

[0037] Figure 9 These are TEM images of the original silica sol used in Example 5;

[0038] Figure 10 These are TEM images of the acetone-type silica sol prepared in Example 5;

[0039] Figure 11 This is a TEM image of the original silica sol used in Example 6;

[0040] Figure 12 This is a TEM image of the paraffin oil-based silica sol prepared in Example 6. Detailed Implementation

[0041] The above-described solution will be further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. The implementation conditions used in the embodiments may be further adjusted according to the conditions of specific manufacturers, and the implementation conditions not specified are generally those in routine experiments.

[0042] Example 1

[0043] At room temperature, 100g of silica sol with a particle size of 20nm and a solid content of 15% was placed in a forced-air drying oven and dried at 120℃. The dried material was mixed with xylene at a ratio of 1:6, and 5% methyltrimethoxysilane was added. The mixture was then ground and dispersed for 20 hours. Insoluble matter was then removed by vacuum filtration to obtain xylene-type silica sol with a particle size of 20nm and a solid content of 12%. Figure 1 This is a TEM image of the original silica sol. Figure 2 The image shows a TEM image of the modified xylene-type silica sol. As can be seen from the comparison, the modified xylene-type silica sol has a uniform distribution, good dispersibility, and no agglomeration.

[0044] Example 2

[0045] At room temperature, 100g of silica sol with a particle size of 52nm and a solid content of 25% was dried in a vacuum oven at 80℃. The dried material was mixed with acetone in a 1:3 ratio, and 2.5% phenyltrimethoxysilane was added. The mixture was ground for 12 hours, and then the insoluble matter was filtered off by pressure filtration to obtain acetone-type silica sol with a particle size of 52nm and a solid content of 23%. Figure 3 This is a TEM image of the original silica sol. Figure 4 The image shows a TEM image of the modified acetone-based silica sol. As can be seen from the comparison, the modified acetone-based silica sol has a uniform distribution, good dispersibility, and no agglomeration.

[0046] Example 3

[0047] At room temperature, 100g of silica sol with a particle size of 35nm and a solid content of 25% was dried in a vacuum oven at 100℃. The dried material was mixed with cyclohexane at a ratio of 1:4, and 3% phenyltrimethoxysilane was added. The mixture was ground and dispersed for 18 hours, and then the insoluble matter was filtered off by vacuum filtration to obtain a cyclohexane-type silica sol with a particle size of 35nm and a solid content of 18%. Figure 5 This is a TEM image of the original silica sol. Figure 6 The image shows a TEM image of the modified cyclohexane-type silica sol. As can be seen from the comparison, the modified cyclohexane-type silica sol has a uniform distribution, good dispersibility, and no agglomeration.

[0048] Example 4

[0049] At room temperature, 100g of silica sol with a particle size of 45nm and a solid content of 35% was dried in a vacuum oven at 120℃. The dried material was dispersed with n-heptane in a 1:2 ratio, and 3% methyltriethoxysilane was added. The mixture was then ground and dispersed for 15 hours. Insoluble matter was then removed by centrifugation to obtain n-heptane-type silica sol with a particle size of 45nm and a solid content of 30%. Figure 7 This is a TEM image of the original silica sol. Figure 8 The image shows a TEM image of the modified n-heptane silica sol. As can be seen from the comparison, the modified n-heptane silica sol has a uniform distribution, good dispersibility, and no agglomeration.

[0050] Example 5

[0051] At room temperature, 100g of silica sol with a particle size of 15nm and a solid content of 15% was dried in a vacuum oven at 120℃. The dried material was mixed with acetone at a ratio of 1:7, and 5% phenyltrimethoxysilane was added. The mixture was ground and dispersed for 20 hours, and then the insoluble matter was filtered off by vacuum filtration to obtain acetone-type silica sol with a solid content of 10% and a particle size of 15nm. Figure 9 This is a TEM image of the original silica sol. Figure 10 The image shows a TEM image of the modified acetone-based silica sol. As can be seen from the comparison, the modified acetone-based silica sol has a uniform distribution, good dispersibility, and no agglomeration.

[0052] Example 6

[0053] At room temperature, 100g of silica sol with a particle size of 75nm and a solid content of 40% was dried in a microwave drying oven at 100℃. The dried material was mixed with paraffin oil at a ratio of 1:1.4, and 1% methyltrimethoxysilane was added. The mixture was ground and dispersed for 12 hours, and then the insoluble matter was removed by vacuum filtration to obtain a paraffin oil-type silica sol with a solid content of 40% and a particle size of 75nm. Figure 11 This is a TEM image of the original silica sol. Figure 12 The image shows a TEM image of the modified paraffin oil-based silica sol. As can be seen from the comparison, the modified paraffin oil-based silica sol has a uniform distribution, good dispersibility, and no agglomeration.

[0054] In summary, the solvent-based silica sol prepared by this method has a uniform distribution, good dispersibility, and no agglomeration, meeting the application requirements. Moreover, the process is simple, does not require the use of a large amount of solvent for replacement, and is energy-saving and environmentally friendly.

[0055] The above embodiments are only for illustrating the technical concept and features of the present invention, and are intended to enable those skilled in the art to understand the content of the present invention and implement it accordingly. They should not be construed as limiting the scope of protection of the present invention. All equivalent transformations or modifications made in accordance with the spirit and essence of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A method for preparing a solvent-based silica sol, characterized in that, Includes the following steps: (1) Take a certain amount of silica sol and put it into a drying device. The silica sol is water-soluble or alcohol-soluble silica sol with a particle size of 10-100 nm. Dry it into a solid at a drying temperature of 80-150℃. The moisture content of the solid obtained is less than 0.5%. (2) Disperse the silica solid obtained in step (1) in a non-polar solvent and add a silane coupling agent for modification; (3) Grind the liquid-solid mixture obtained in step (2) for a period of time; (4) Filter out the insoluble matter in the liquid obtained in step (3) to obtain the desired solvent-based silica sol.

2. The method for preparing solvent-based silica sol according to claim 1, characterized in that: In step (2), the mass ratio of the nonpolar solvent to the solid obtained in step (1) is 1:1 to 9:

1.

3. The method for preparing solvent-based silica sol according to claim 1, characterized in that: The amount of silane coupling agent in step (2) is 1% to 5% of the amount of solid substance obtained in step (1).

4. The method for preparing solvent-based silica sol according to claim 1, characterized in that: In step (2), the non-polar solvent is one of cyclohexane, acetone, xylene, n-heptane, or paraffin oil.

5. The method for preparing solvent-based silica sol according to claim 1, characterized in that: In step (2), the silane coupling agent is one of methyltrimethoxysilane, phenyltrimethoxysilane, methyltriethoxysilane, propyltrimethoxysilane, dimethyldimethoxysilane, or dimethyldiethoxysilane.

6. The method for preparing solvent-based silica sol according to claim 1, characterized in that: The grinding time in step (3) is 12 to 24 hours.

7. The method for preparing solvent-based silica sol according to claim 1, characterized in that: In step (4), the filtration method is one of vacuum filtration, pressure filtration, or centrifugation.

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