Nanometer silicon oxide butyl acetate dispersion liquid and preparation method thereof

Abstract

The invention discloses a nanometer silicon oxide butyl acetate dispersion liquid and a preparation method thereof, the dispersion liquid is formed by grafting linear organic molecular chains on the surface of a nanometer silicon oxide near-spherical colloidal nucleus, and colloidal particles are dispersed in butyl acetate; one end of the organic molecular chain is siloxy playing a connecting role, and the other end of the organic molecular chain is an organic functional group connected with a silicon atom. The preparation method comprises the following steps: by taking silica sol as a raw material, adding acid to adjust the pH value to 2.0-5.5, adding a low-boiling-point water-soluble organic solvent, and mixing to obtain a mixed solution A; adding a silane coupling agent into the A, and reacting the silane coupling agent with water in the mixed solution until a dispersion solution B is obtained; adding butyl acetate into B, and heating and distilling to remove the low-boiling-point water-soluble organic solvent, so as to obtain the nano silicon oxide butyl acetate dispersion liquid. The product has the advantages of high purity, stable quality, good dispersibility and the like, the application range of the product is expanded, the preparation process is safe and environment-friendly, and various supervision requirements can be met.

Description

Technical Field

[0001] The present invention relates to a nano-silica dispersion liquid and a preparation method thereof, in particular to a nano-silica butyl acetate dispersion liquid and a preparation method thereof. Background Art

[0002] As an important inorganic nano material widely used, nano-SiO2 has poor compatibility and dispersibility in organic solvents due to its rich surface hydroxyl groups, strong hydrophilicity and easy agglomeration, which affects its application performance and application scope.

[0003] As a basic ester chemical material, butyl acetate has a moderate volatility, low acute toxicity, and good solubility in many polymers, and has a wide range of uses, including being used as a solvent for nitrocellulose paint, polyurethane paint, etc., for aircraft wing coatings, artificial leather coatings, automotive coatings, etc. In these applications, if doped and modified with nano materials, its application performance can be further improved, such as better hardness, scratch resistance and weather resistance.

[0004] However, the actual situation is that the existing reports on the nano-silica organic solvent dispersion liquid focus on the dispersion liquid of low-boiling alcohols, and there are few research reports on the nano-silica butyl acetate, and even fewer research reports on the butyl acetate dispersion liquid of other nano materials. The only thing that can be retrieved is, for example, the butyl acetate dispersion liquid product of Suzhou Youzir Environmental Protection Technology Co., Ltd. Although no specific preparation process description is found, the product introduction shows that the appearance is "semi-transparent", which indicates that at least many of the particle sizes in the dispersion liquid exceed half of the visible light wavelength (i.e., greater than about 200 nm).

[0005] In addition, in the master's thesis "Research on the Dispersion Stability of Nano-ITO Particles in Butyl Acetate Phase" by Zhang Lei of Xi'an University of Science and Technology in 2011, it is introduced that the stable dispersion of nano-indium tin oxide (ITO) slurry in the ester phase is realized for the first time by surface modification and dispersant regulation using nano-ITO powder. The selection of dispersants is particularly introduced, the effects of dispersants such as polyethylene glycol (PEG), polyvinylpyrrolidone (PVP), and titanate on the dispersion effect are evaluated, the types and ratios of dispersants are optimized, and the relevant mechanisms are further analyzed.

[0006] The above process uses nanomaterial powders as raw materials. However, for nano-SiO2, due to the large number of hydroxyl groups on its particle surface and high surface energy, it is extremely easy for nanoparticles to agglomerate, and it is difficult to disperse them. Even through shearing and ultrasonic dispersion during the process, it is difficult to truly and completely disperse the particles sufficiently. When a dispersant is added for stabilization, it can only stabilize the dispersed particles so that they do not re-agglomerate. Microscopically, the resulting product inevitably contains some larger particles (such as those larger than 200 nm), and macroscopically, it appears as a milky translucent dispersion. These will affect the application performance of the dispersion and subsequent related products.

[0007] In addition, for example, when used in polyurethane paints, not only is it required that the added substances be transparent in appearance, but also due to the presence of active NCO groups, it is required that the added substances have a high purity to ensure that the performance of the paint itself is not affected. However, the aforementioned process and products obviously cannot meet this requirement.

[0008] Therefore, the purity, stability, and dispersibility of existing silica butyl acetate dispersion products all need to be improved, which also limits their scope of use. Summary of the Invention

[0009] The problem to be solved by the present invention is to overcome the deficiencies in the prior art and provide a nano-silica butyl acetate dispersion with high product purity, stable quality, and good dispersibility and its preparation process to expand its scope of use. At the same time, its preparation process is safe and environmentally friendly and can meet the requirements of various current regulations.

[0010] To achieve the above object, the present invention adopts the following technical solution: A nano-silica butyl acetate dispersion, wherein the structure of the nano-silica is that a near-spherical colloidal core with a particle size of 8 - 20 nm is grafted with linear organic molecular chains, and the linear organic molecular chains are intertwined with each other and distributed around the colloidal core, and the formed colloidal particles are dispersed in butyl acetate; by weight, the sum of the nano-silica and the grafted organic molecular chains is 20 - 40%, and butyl acetate is 60 - 80%. One end of the organic molecular chain is a siloxy group for connection, and the other end is an organic functional group connected to the silicon atom. The organic functional group includes functional group A and functional group B. Functional group A is one or any two of methyl, vinyl, and glycidyl ether oxypropyl, and functional group B is a mixture of hydroxyl and methoxy, or hydroxyl and ethoxy, or hydroxyl, methoxy, and ethoxy.

[0011] The preparation method of the above-mentioned nano-silica butyl acetate dispersion liquid comprises the following steps: (1) Using silica sol with a silica mass percentage content of 20%-40% as the raw material, adjusting the pH value to 2.0-5.5 with an acid, and then adding a low-boiling-point water-soluble organic solvent, mixing evenly to obtain a mixed liquid A; the low-boiling-point water-soluble organic solvent is an organic solvent that can dissolve in both water and butyl acetate, and the addition amount of the low-boiling-point water-soluble organic solvent is 1.5-2.5 times the weight of the water in the silica sol; the low-boiling-point water-soluble organic solvent is any one or any two of methanol, ethanol, and isopropanol; (2) Adding a silane coupling agent to the above-mentioned mixed liquid A to react with the water in the mixed liquid. After reacting until the sampled reaction liquid can be miscible with butyl acetate in a volume ratio of 1:1 and the mixed liquid is transparent and does not separate into layers, a dispersion liquid B is obtained; the addition amount of the silane coupling agent is 0.23-0.28 times the amount of water contained in the silica sol in terms of mol; (3) Adding butyl acetate to the dispersion liquid B, mixing evenly, and then heating and distilling to remove the low-boiling-point water-soluble organic solvent to obtain a nano-silica butyl acetate dispersion liquid; the addition amount of the butyl acetate is 1.5-4.0 times the total weight of the nano-silica and the grafted organic molecular chains in the dispersion liquid B; the heating and distillation temperature is controlled to gradually increase from room temperature to 110-115°C.

[0012] The silane coupling agent is KH560 or KH151 or methyltriethoxysilane or methyltriethoxysilane, or a mixture of two of them. The acid is hydrochloric acid or formic acid or acetic acid, or a mixture of two of them.

[0013] Due to the adoption of the above method, the present invention uses silica sol with a particle size of 8-20 nm as the raw material to complete the whole process of surface modification of nano-particles and dispersion in butyl acetate in the liquid phase, avoiding the agglomeration problem of conventional nano-powders during the drying process. The nano-particles have good dispersibility and the product appearance is transparent. At the same time, due to the steric hindrance effect of the linear organic molecular chains grafted on the nano-particles, the stability of the dispersion liquid is ensured. The dispersion liquid does not need to introduce various dispersants, ensuring the purity of the product.

[0014] Compared with the prior art, the beneficial effects of this aspect are as follows:

[0015] First, due to the adoption of silica sol with a particle size of 8-20 nm as the raw material, the whole process of surface modification and dispersion in butyl acetate is completed in the liquid phase, avoiding the agglomeration problem of conventional nano-powders during the drying process. The obtained product has good dispersibility of nano-particles and the product appearance is clear and transparent.

[0016] At the same time, to avoid the occurrence of gel phenomenon during the process, the present invention introduces an organic solvent with good compatibility with hydrophilic silica, hydrophobic silica, and butyl acetate as a transition solvent, avoiding the occurrence of gel and agglomeration during the process and ensuring the dispersibility of nano-particles in the dispersion liquid.

[0017] II. In the present invention, a silane coupling agent is added to the silica sol. By utilizing the reaction between the silane coupling agent and water, after the reaction is completed, an alcohol dispersion of silica can be directly obtained without dehydration operation. Meanwhile, in this process, along with the hydrolysis reaction of the silane coupling agent, the silane hydrolyzate reacts with the hydroxyl groups on the surface of the silica sol colloid, synchronously realizing the surface modification of the silica sol particles. In this way, by virtue of the steric hindrance effect brought by the organic groups grafted on the particles, no additional dispersant and stabilizer are required, the product has good stability and relatively high purity, meeting the design requirements of the product.

[0018] III. The process of the present invention is simple. All process operations can be completed in one reactor, and the low-boiling-point alcohol obtained from the evaporation process can be recycled. The process is safe, environmentally friendly, and can meet the process requirements of green production.

[0019] Therefore, the nano-silica butyl acetate dispersion and its preparation process of the present invention overcome the deficiencies in the prior art, having the advantages of relatively high product purity, stable quality, good dispersibility, etc., expanding its scope of use. For example, it can be used for the nano-material modification of polyurethane paint, and the product prepared by the process can meet the application requirements. At the same time, the preparation process of the present invention is safe and environmentally friendly, and can meet the requirements of various current regulations. Specific Embodiments

[0020] The silica sol used in the following examples can be selected as commercially available basic silica sol, such as the basic silica sol produced by Zhejiang Yuda Chemical Co., Ltd., and the rest of the reagents are all of analytical grade.

[0021] Example 1

[0022] Transfer 100 g of silica sol with a particle size of 8 nm and a content of 20% to a three-necked flask, and start stirring (stirring speed 200 r / min). After adjusting the pH value of the silica sol to 2.0 by dropping hydrochloric acid at a rate of 1 mL / min using a constant-pressure dropping funnel, continue stirring for 15 min, add 200 g of methanol, and then continue stirring for 15 min. Then, add 294 g of KH560 (γ-glycidoxypropyltrimethoxysilane) at a rate of about 10 mL / min, and continue stirring after adding.

[0023] After stirring for 12 hours, take a sample for detection: Take 3 - 5 ml of the sample, add an equal volume of butyl acetate reagent, gently shake the test tube to mix the two liquids, and then let it stand and observe. The mixed liquid does not separate, and it is visually uniform and transparent, indicating that the reaction is basically completed (if the mixed liquid becomes turbid after mixing, continue stirring the reaction, and then take a sample for testing every 2 - 3 hours until the detected mixed liquid is transparent).

[0024] Continue stirring for 3 hours to make the reaction more complete. Then add 355 g of butyl acetate, continue stirring for 1 hour after mixing, turn on the condensation reflux (cooling water temperature 15 - 20 °C), and slowly heat up at a rate of approximately 1 °C / min and recover the condensate.

[0025] When the temperature rises to 70 °C, condensate starts to drip, and by around 110 °C, the dripping has basically stopped. Continue heating up to 113 °C and maintain for 10 min, then cool naturally.

[0026] Observe the dispersion liquid, which is transparent in appearance. Weigh and obtain 570 g of the dispersion liquid. The dispersion liquid has a high purity, stable quality, and good dispersibility.

[0027] According to the method of GB / T 1725 - 2007 "Determination of non-volatile content of paints, varnishes and plastics" (test conditions: constant temperature at 120 °C for 24 h), the non-volatile content of this dispersion liquid is measured to be 40.0%. The main component of this non-volatile matter is the modified nano-silica obtained by grafting organic molecular chains on the surface of nano-silica.

[0028] Note: Considering that a small amount of butyl acetate will be volatilized and carried out with the alcohol, the addition amount of butyl acetate is slightly more than the calculated amount.

[0029] Example 2

[0030] Transfer 100 g of silica sol with a particle size of 10 nm and a content of 24% to a three-necked flask and start stirring (stirring speed 200 r / min). Use a constant-pressure dropping funnel to drop a mixed solution of hydrochloric acid and acetic acid with a mol ratio of 1:1 at a rate of 1 mL / min. After adjusting the pH value of the silica sol to 4.0, continue stirring for 15 min, add 175 g of ethanol, and then continue stirring for 15 min. Then add 217 g of silane A151 (vinyltriethoxysilane) at a rate of approximately 10 mL / min. After adding, continue stirring.

[0031] After stirring for 12 hours, take a sample for detection: Take 3 - 5 ml of the sample, add an equal volume of butyl acetate reagent, gently shake the test tube to mix the two liquids, and then let it stand and observe. The mixed liquid does not separate layers, and it is visually uniform and transparent, indicating that the reaction has basically been completed (if the mixed liquid becomes turbid after mixing, continue stirring the reaction, and then take a sample for testing every 2 - 3 hours until the detected mixed liquid is transparent).

[0032] Continue stirring for 1 hour to make the reaction more complete. Then add 258 g of butyl acetate, continue stirring for 1 hour after mixing, turn on the condensation reflux (cooling water temperature 15 - 20 °C), and slowly heat up at a rate of approximately 1 °C / min and recover the condensate.

[0033] When the temperature rises to 70 °C, condensate starts to drip, and by around 110 °C, the dripping has basically stopped. Continue heating up to 115 °C and maintain for 10 min, then cool naturally.

[0034] The dispersion liquid was observed. It was transparent in appearance. The collected dispersion liquid weighed 362 g. The dispersion liquid had a high purity, stable quality, and good dispersibility.

[0035] According to the method of GB / T 1725-2007 "Determination of non-volatile content of paints, varnishes and plastics" (test conditions: constant temperature at 120 °C for 24 h), the non-volatile content of this dispersion liquid was measured to be 31.5%. The main component of this non-volatile matter was modified nano-silica obtained by grafting organic molecular chains on the surface of nano-silica.

[0036] Example 3

[0037] 100 g of silica sol with a particle size of 12 nm and a content of 28% was transferred to a three-necked flask, and stirring was started (rotation speed 200 r / min). After adjusting the pH value of the silica sol to 3.0 by dropping formic acid at a rate of 1 mL / min using a constant-pressure dropping funnel, stirring was continued for 15 min. Then 152 g of isopropyl alcohol was added, and after stirring for another 15 min, 142 g of methyltrimethoxysilane was added at a rate of about 10 mL / min. After adding, stirring was continued.

[0038] After stirring for 12 hours, a sample was taken for detection: 3 - 5 ml of the sample was taken, an equal volume of butyl acetate reagent was added, the test tube was gently shaken to mix the two liquids, and then left to stand and observe. The mixed liquid did not separate, and it was visually observed to be uniformly transparent, indicating that the reaction was basically complete.

[0039] Stirring was continued for 2 hours to make the reaction more complete. Then 320 g of butyl acetate was added, and after mixing, stirring was continued for 1 hour. The condensation reflux was started (cooling water temperature 15 - 20 °C), and the temperature was slowly raised at a rate of approximately 1 °C / min while recovering the condensate.

[0040] When the temperature rose to 70 °C, condensate began to drip. By about 110 °C, the dripping had basically stopped. The temperature was continued to be raised to 113 °C and maintained for 10 min, and then it was naturally cooled.

[0041] The dispersion liquid was observed. It was transparent in appearance. The collected dispersion liquid weighed 410 g. The dispersion liquid had a high purity, stable quality, and good dispersibility.

[0042] According to the method of GB / T 1725-2007 "Determination of non-volatile content of paints, varnishes and plastics" (test conditions: constant temperature at 120 °C for 24 h), the non-volatile content of this dispersion liquid was measured to be 23.9%. The main component of this non-volatile matter was modified nano-silica obtained by grafting organic molecular chains on the surface of nano-silica.

[0043] Example 4

[0044] Transfer 100 g of silica sol with a particle size of 15 nm and a content of 32% to a three-necked flask, and start stirring (rotation speed 200 r / min). Using a constant-pressure dropping funnel, add a mixed solution of formic acid and acetic acid with a molar ratio of 1:1 at a rate of 1 mL / min. After adjusting the pH value of the silica sol to 4.5, continue stirring for 15 min, add 32.5 g of methanol and 97.5 g of isopropanol, and then continue stirring for 15 min. Then, add 168 g of methyltriethoxysilane at a rate of about 10 mL / min, and continue stirring after adding.

[0045] After stirring for 12 hours, take a sample for testing: Take 3 - 5 ml of the sample, add an equal volume of butyl acetate reagent, gently shake the test tube to mix the two liquids, and then let it stand and observe. If the mixed liquid does not separate layers and is visually homogeneous and transparent, it indicates that the reaction is basically complete.

[0046] Continue stirring for 1 hour to make the reaction more complete. Then add 175 g of butyl acetate, mix and continue stirring for 1 hour. Start the condensation reflux (cooling water temperature 15 - 20 °C), and slowly heat up at a rate of approximately 1 °C / min and recover the condensate.

[0047] When the temperature rises to 70 °C, condensate starts to drip. When it reaches about 110 °C, the dripping has basically stopped. Continue heating up to 113 °C and keep it for 10 min, then cool naturally.

[0048] Observe the dispersion liquid. It is transparent in appearance. Weigh and obtain 263 g of the dispersion liquid. The dispersion liquid has a high purity, stable quality, and good dispersibility.

[0049] According to the method of GB / T 1725 - 2007 "Determination of Non-Volatile Content of Paints, Varnishes and Plastics" (test conditions: constant temperature at 120 °C for 24 h), the non-volatile content of this dispersion liquid is measured to be 36.4%. The main component of this non-volatile matter is modified nano-silica obtained by grafting organic molecular chains on the surface of nano-silica.

[0050] Example 5

[0051] Transfer 100 g of silica sol with a particle size of 18 nm and a content of 36% to a three-necked flask, and start stirring (rotation speed 200 r / min). Using a constant-pressure dropping funnel, add a mixed solution of hydrochloric acid and formic acid with a molar ratio of 1:1 at a rate of 1 mL / min. After adjusting the pH value of the silica sol to 3.5, continue stirring for 15 min, add 54.5 g of ethanol and 54.5 g of isopropanol, and then continue stirring for 15 min. Then, add 102 g of KH560 (γ-glycidoxypropyltrimethoxysilane) and 59 g of methyltrimethoxysilane at a rate of about 10 mL / min, and continue stirring after adding.

[0052] After stirring for 12 hours, take a sample for testing: Take 3 - 5 ml of the sample, add an equal volume of butyl acetate reagent, gently shake the test tube to mix the two liquids, and then let it stand and observe. The mixed liquid does not separate, and it is visually uniform and transparent, indicating that the reaction is basically complete.

[0053] Add 306 g of butyl acetate, continue to stir for 1 hour after mixing, turn on the condensation reflux (cooling water temperature 15 - 20 °C), and slowly heat up at a rate of approximately 1 °C / min and recover the condensate.

[0054] When the temperature rises to 70 °C, condensate starts to drip. When it reaches about 110 °C, the dripping has basically stopped. Continue to heat up to 115 °C and maintain it for 10 min, then cool down naturally.

[0055] Observe the dispersion liquid. The appearance is transparent. Weigh and obtain 433 g of the dispersion liquid. The dispersion liquid has a high purity, stable quality, and good dispersibility.

[0056] According to the method of GB / T 1725 - 2007 "Determination of non - volatile content of paints, varnishes and plastics" (test conditions: constant temperature at 120 °C for 24 h), the non - volatile content of this dispersion liquid is measured to be 31.6%. The main component of this non - volatile matter is modified nano - silica obtained by grafting organic molecular chains on the surface of nano - silica.

[0057] Note: The mixed acid of hydrochloric acid and formic acid is pre - diluted with a small amount of deionized water in advance. Because the amount used is small, it is not carefully calculated, but a slightly larger amount is added when adding silane to make up for it.

[0058] Example 6

[0059] Transfer 100 g of silica sol with a particle size of 20 nm and a content of 40% to a three - necked flask, and start stirring (stirring speed 200 r / min). Use a constant - pressure dropping funnel to drop acetic acid at a rate of 1 mL / min to adjust the pH value of the silica sol to 5.5. Then continue to stir for 15 min, add 60 g of methanol and 30 g of ethanol, and then continue to stir for 15 min. Then add 90 g of KH560 (γ - glycidoxypropyltrimethoxysilane) and 73 g of silane A151 (vinyltriethoxysilane) at a rate of about 10 mL / min. After adding, continue to stir.

[0060] After stirring for 12 hours, take a sample for testing: Take 3 - 5 ml of the sample, add an equal volume of butyl acetate reagent, gently shake the test tube to mix the two liquids, and then let it stand and observe. The mixed liquid does not separate, and it is visually uniform and transparent, indicating that the reaction is basically complete.

[0061] Continue to stir for 1 hour to make the reaction more complete. Then add 545 g of butyl acetate, continue to stir for 1 hour after mixing, turn on the condensation reflux (cooling water temperature 15 - 20 °C), and slowly heat up at a rate of approximately 1 °C / min and recover the condensate.

[0062] Condensate began to drip when the temperature was raised to 70 °C, and there was basically no dripping at about 110 °C. Then it was continuously heated to 115 °C and maintained for 10 min, and then cooled naturally.

[0063] The dispersion was observed. Its appearance was transparent, and 665 g of the dispersion was obtained by weighing. The dispersion had a high purity, stable quality and good dispersibility.

[0064] According to the method of GB / T 1725-2007 Determination of non-volatile matter content of paints, varnishes and plastics (test conditions: constant temperature at 120 °C for 24 h), the non-volatile matter content of this dispersion was measured to be 19.9%. The main component of this non-volatile matter was modified nano-silica obtained by grafting organic molecular chains on the surface of nano-silica.

[0065] For the 6 specimens prepared in the above Examples 1-6, according to GB / T 6753.3-1986 Test method for storage stability of paints, specifically, the temperature was controlled at 50 ± 2 °C, and after being stored for 15 days, they were taken out and observed: the specimen of Example 1 had obvious thickening, but still had a little fluidity, its appearance was still transparent, and there was no sediment; for the other five specimens of Examples 2-6, there was no obvious thickening, the appearance was normal, transparent, without turbidity and sediment.

[0066] Based on the above-mentioned situations of the examples, it shows that the dispersibility and dispersion stability of the dispersion of the product of the process of this patent meet the requirements.

Claims

1. A nano silicon oxide butyl acetate dispersion, characterized in that The structure of the nano silicon oxide is that a nearly spherical colloid core with a particle size of 8-20nm is grafted with linear organic molecular chains on the surface, and the linear organic molecular chains are entangled with each other and distributed around the colloid core to form colloid particles dispersed in butyl acetate. By weight, the sum of the nano silicon oxide and the grafted organic molecular chains is 20-40%, and the butyl acetate is 60-80%.

2. The nano silicon oxide butyl acetate dispersion according to claim 1, characterized in that One end of the organic molecular chain is a siloxy group that plays a connecting role, and the other end is an organic functional group connected to the silicon atom, wherein the organic functional group includes functional group A and functional group B, wherein the functional group A is one or any two of methyl, vinyl, and glycidyloxypropyl, and the functional group B is a hydroxyl and methoxyl group or a hydroxyl and ethoxyl group, or a mixture of a hydroxyl, methoxyl group, and ethoxyl group.

3. The nano silicon oxide butyl acetate dispersion according to claim 1 or 2, characterized in that The preparation method comprises the following steps: (1) using a silica sol containing 20% ​​to 40% by mass of silica as a raw material, adding acid to adjust the pH value to 2.0 to 5.5, then adding a low-boiling point water-soluble organic solvent, and mixing uniformly to obtain a mixed solution A; the low-boiling point water-soluble organic solvent is an organic solvent that is soluble in both water and butyl acetate, and the amount of the low-boiling point water-soluble organic solvent added is 1.5 to 2.5 times the weight of water in the silica sol; the low-boiling point water-soluble organic solvent is any one of methanol, ethanol, and isopropanol, or a mixture of any two thereof; (2) adding a silane coupling agent to the mixed solution A to react with the water in the mixed solution until the reaction solution is miscible with butyl acetate in a volume ratio of 1:1 when sampled and tested, and the mixed solution is transparent and does not separate, thereby obtaining a dispersion B; the amount of the silane coupling agent added is 0.23-0.28 times the amount of water contained in the silica sol in terms of molar amount; (3) adding butyl acetate to dispersion B, mixing evenly, heating and distilling to remove the low-boiling point water-soluble organic solvent, and obtaining a nano-silicon oxide butyl acetate dispersion; the amount of butyl acetate added is 1.5-4.0 times the total weight of the nano-silicon oxide and the grafted organic molecular chain in dispersion B; and the heating and distillation temperature is controlled to gradually increase from room temperature to 110-115° C.

4. The method for preparing a nano-silicon oxide butyl acetate dispersion according to claim 3, wherein the silane coupling agent is KH560 or KH151 or methyltriethoxysilane or methyltriethoxysilane, or a mixture of two thereof.

5. The method for preparing a nano-silicon oxide butyl acetate dispersion according to claim 3, wherein the acid is hydrochloric acid, formic acid, acetic acid, or a mixture of two thereof.