Double-particle-size silica sol as well as preparation method and application thereof

Abstract

The invention relates to double-particle-size silica sol and a preparation method and application thereof.The preparation method comprises the steps that an alcohol-water solvent is prepared, then the pH value is adjusted through a basic catalyst, and mother liquor with the pH value being 9-12 is obtained; adding a first silicon source into the mother liquor in batches for reaction to grow first silicon dioxide particles, and obtaining a first reaction product after the reaction is finished; mixing the first reaction product with hydrolysate of a silane coupling agent for reaction, and obtaining a second reaction product after the reaction is finished; a second silicon source is added into the second reaction product in batches for a reaction, second silicon dioxide particles grow, the double-particle-size silica sol is obtained after the reaction is finished, and the particle size of the first silicon dioxide particles is larger than that of the second silicon dioxide particles. According to the preparation method, one-step preparation of the double-particle-size silica sol is achieved, the proportion of the two particles with different particle sizes can be accurately controlled, and meanwhile the two particles in the double-particle-size silica sol are uniform in particle size, good in stability and high in dispersity.

Description

Technical Field

[0001] The invention relates to the technical field of silica sol, in particular to a double-particle-size silica sol and a preparation method and application thereof. Background Art

[0002] At present, the preparation of dual-particle size silica sol can be roughly divided into direct mixing method and one-step synthesis method. Among them, the direct mixing method is to first prepare two silica particles with different particle sizes, and then mix them according to a certain ratio. However, since two silica particles with different particle sizes need to be prepared separately, the direct mixing method is cumbersome and costly. At the same time, there is also the problem of decreased stability of dual-particle size silica sol after mixing; the one-step synthesis method usually synthesizes small-particle size silica particles first, and then increases the particle size of some silica particles by chemical means, such as allowing some silica particles to continue to grow. However, this method cannot accurately control the proportion of particles with two different particle sizes, and this method also has problems such as wide dispersion of single particles, poor dispersion and stability. Summary of the invention

[0003] Based on this, it is necessary to provide a double-particle size silica sol and its preparation method and application to address the above problems. The preparation method realizes the one-step preparation of double-particle size silica sol, and the particle size of the two particles in the double-particle size silica sol is uniform, the mass ratio is controllable, the stability is good and the dispersion is high.

[0004] A method for preparing a double-particle-size silica sol comprises the following steps:

[0005] Prepare an alcohol-water solvent, and then use an alkaline catalyst to adjust the pH to obtain a mother solution with a pH of 9-12;

[0006] Adding a first silicon source to the mother solution in batches for reaction to grow first silicon dioxide particles, and obtaining a first reaction product after the reaction is completed;

[0007] The first reaction product is mixed with a hydrolyzate of a silane coupling agent to react, and after the reaction is completed, a second reaction product is obtained;

[0008] A second silicon source is added to the second reaction product in batches for reaction to grow second silicon dioxide particles. After the reaction is completed, a double-particle-size silica sol is obtained, wherein the particle size of the first silicon dioxide particles is larger than that of the second silicon dioxide particles.

[0009] In one embodiment, the first silicon source and the second silicon source are independently selected from at least one of methyl orthosilicate, ethyl orthosilicate, propyl orthosilicate, butyl orthosilicate, sodium silicate, and potassium silicate.

[0010] In one embodiment, the step of adding the first silicon source to the mother liquor in batches to react satisfies at least one of the following conditions:

[0011] (1) The temperature of the mother liquor is 50° C.-90° C.;

[0012] (2) The temperature fluctuation during the reaction is within 5°C;

[0013] (3) The time for adding the first silicon source in batches is 4h-24h.

[0014] In one embodiment, the solid content of the first reaction product is 5%-10%.

[0015] In one embodiment, the step of mixing the first reaction product with the hydrolyzate of the silane coupling agent to react satisfies at least one of the following conditions:

[0016] (1) The general formula of the silane coupling agent is R 1 -Si-(OR 2 ) 3 , where -R 1 It is an alkyl group or an isomer of an alkyl group, with 1 to 12 carbon atoms, -OR 2 is a hydrolyzable group;

[0017] (2) The amount of the silane coupling agent is 1wt%-20wt% of the solid content in the first reaction product;

[0018] (3) The reaction temperature is 25°C-95°C and the reaction time is 0.5h-4h.

[0019] In one embodiment, the method for preparing the hydrolyzate of the silane coupling agent comprises the following steps:

[0020] Prepare an alcohol-water solvent, and then use an acid catalyst to adjust the pH to 1-5 to obtain a mixed solution;

[0021] A silane coupling agent is added to the mixed solution, and the mixed solution is hydrolyzed to obtain a hydrolyzed solution of the silane coupling agent.

[0022] In one embodiment, the step of adding the second silicon source to the second reaction product in batches to react satisfies at least one of the following conditions:

[0023] (1) The temperature of the second reaction product is 50° C.-90° C.;

[0024] (2) The temperature fluctuation during the reaction is within 5°C;

[0025] (3) The time for adding the second silicon source in batches is 2h-6h.

[0026] A double-particle-size silica sol obtained by adopting the preparation method.

[0027] An application of the double-particle silica sol in a polishing liquid.

[0028] In one embodiment, the particle size of the first silica particles in the dual-particle silica sol is 80 nm-200 nm, the particle size of the second silica particles is 10 nm-60 nm, and the mass ratio of the first silica particles to the second silica particles is 1:1-4:1.

[0029] In the preparation method of the present invention, the first silica particles with a target large particle size are first synthesized, and then the condensation effect of the silane coupling agent and the surface hydroxyl group of the first silica particles is used to realize the surface occupancy of the first silica particles, and the in-situ growth of the second silicon source added subsequently on the first silica particles is suppressed, so that the second silicon source forms a new core. Since the new core has a high specific surface energy, the second silicon source added in batches subsequently will continue to grow on the new core to obtain the second silica particles with a target small particle size, and the particle size of the first silica particles is maintained substantially unchanged. Therefore, the present invention grows the second silica particles with a small particle size through secondary nucleation, rather than obtaining a double-particle-size silica sol by increasing the particle size of some silica particles, and can accurately control the proportion of particles with two different particle sizes, and the particle size of the two particles in the double-particle-size silica sol is uniform, stable and highly dispersed. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the conventional technology, the drawings required for use in the embodiments or the conventional technology descriptions are briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0031] Figure 1 This is a SEM image of the double-particle silica sol prepared in Example 1;

[0032] Figure 2 This is a SEM image of the double-particle silica sol prepared in Example 2;

[0033] Figure 3 This is a SEM image of the double-particle silica sol prepared in Example 3;

[0034] Figure 4 This is the SEM image of the silica sol prepared in Comparative Example 1. DETAILED DESCRIPTION

[0035] For ease of understanding of the present invention, the present invention will be described in more detail below. However, it should be understood that the present invention can be implemented in many different forms and is not limited to the embodiments or examples described herein. On the contrary, the purpose of providing these embodiments or examples is to make the understanding of the disclosure of the present invention more thorough and comprehensive.

[0036] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those generally understood by those skilled in the art of the present invention. The terms used herein in the specification of the present invention are only for the purpose of describing specific implementation methods or embodiments, and are not intended to limit the present invention. The optional scope of the term "and / or" used herein includes any one of two or more related listed items, and also includes any and all combinations of related listed items, and the combinations include any two related listed items, any more related listed items, or all related listed items.

[0037] In the present invention, when it comes to numerical ranges, unless otherwise specified, the above numerical ranges are deemed to be continuous and include the minimum and maximum values ​​of the range, as well as each value between such minimum and maximum values. Further, when a range refers to an integer, each integer between the minimum and maximum values ​​of the range is included. In addition, when multiple ranges are provided to describe features or characteristics, the ranges can be merged. In other words, unless otherwise specified, all ranges disclosed herein should be understood to include any and all subranges included therein.

[0038] The preparation method of the double-particle-size silica sol provided by the present invention comprises the following steps:

[0039] S1, preparing an alcohol-water solvent, and then adjusting the pH with an alkaline catalyst to obtain a mother solution with a pH of 9-12;

[0040] S2, adding a first silicon source to the mother solution in batches for reaction to grow first silicon dioxide particles, and obtaining a first reaction product after the reaction is completed;

[0041] S3, mixing the first reaction product with the hydrolyzate of the silane coupling agent to react, and obtaining a second reaction product after the reaction is completed;

[0042] S4, adding a second silicon source to the second reaction product in batches for reaction to grow second silicon dioxide particles, and obtaining a double-particle-size silica sol after the reaction is completed, wherein the particle size of the first silicon dioxide particles is larger than the particle size of the second silicon dioxide particles.

[0043] In step S1, when preparing the alcohol-water solvent, the volume ratio of water to alcohol is preferably 0.1:1-0.5:1, wherein the alcohol is selected from at least one of methanol, ethanol, propanol, butanol, isopropanol, and pentanol.

[0044] Optionally, the alkaline catalyst used to adjust the pH is selected from at least one of ammonia water, urea, potassium hydroxide, sodium hydroxide, tetramethylammonium hydroxide, diethylamine, and triethylamine. The alkaline catalyst can catalyze the hydrolysis and condensation of the silicon source into spheres, and on the other hand, the OH - It can be adsorbed on the surface of the generated silica particles, and the electrostatic effect is used to stabilize the entire system without precipitation.

[0045] Since the pH of the mother liquor directly affects the particle size of the silica particles, if the pH is too low, the particle size of the generated silica particles will be uneven, and if the pH is too high, it will be unfavorable for generating silica particles with large particle sizes. Therefore, the present invention uses an alkaline catalyst to adjust the mother liquor to a pH of 9-12 to ensure the uniformity of the particle size of the generated silica particles.

[0046] In step S2, before adding the first silicon source to the mother liquor in batches for reaction, the mother liquor is first heated to 50°C-90°C by heating in a water bath or the like, and then the first silicon source is added to the mother liquor in batches, wherein the first silicon source is selected from at least one of methyl orthosilicate, ethyl orthosilicate, propyl orthosilicate, butyl orthosilicate, sodium silicate and potassium silicate, and the batch addition method is dropwise addition, and when dropwise addition is adopted, it can be continuous dropwise addition or intermittent dropwise addition.

[0047] By adjusting the addition rate of the first silicon source, the particle size of the generated first silicon dioxide particles can also be adjusted. Therefore, the addition rate of the first silicon source can be adjusted according to the target particle size of the first silicon dioxide particles in the dual-particle silica sol. Preferably, the time for adding the first silicon source in batches is preferably 4h-24h.

[0048] In order to make the particle size of the first silicon dioxide particles generated by the reaction more uniform, it is preferred that the temperature fluctuate within 5° C., more preferably in a constant temperature state, when the first silicon source is added to the mother solution in batches for reaction.

[0049] It should be noted that the solid content of the first reaction product, i.e., the mass fraction of the first silica particles in the first reaction product, is adjusted to 5%-10% by adjusting the solid content of the first reaction product, which is also conducive to making the particle size of the generated first silica particles more uniform. It is understandable that the amount of the first silicon source can be calculated by presetting the solid content of the first reaction product. For example, when the solid content is 5%, 100g of the first reaction product contains 5g of the first silica particles. At this time, if tetraethoxysilane is selected as the first silicon source, 17.34g is required.

[0050] In step S3, when the first reaction product is mixed with the hydrolyzate of the silane coupling agent for reaction, the reaction temperature is preferably 25°C-95°C, and the reaction time is preferably 0.5h-4h. During the reaction, the silane coupling agent will undergo a condensation reaction with the hydroxyl groups on the surface of the first silica particles, be grafted on the surface of the first silica particles, and occupy the surface of the first silica particles.

[0051] Optionally, the preparation method of the hydrolyzate of the silane coupling agent comprises the following steps: preparing an alcohol-water solvent, then adjusting the pH to 1-5, preferably adjusting the pH to 2.5-4, using an acid catalyst to obtain a mixed solution, adding a silane coupling agent to the mixed solution, and obtaining the hydrolyzate of the silane coupling agent after hydrolysis. Wherein, the volume ratio of alcohol to water is preferably 1:1-5:1, the alcohol is selected from at least one of methanol, ethanol, propanol, butanol, isopropanol, and amyl alcohol, and the acid catalyst is selected from at least one of hydrochloric acid, sulfuric acid, oxalic acid, acetic acid, formic acid, nitric acid, and citric acid. The acid catalyst can not only catalyze the hydrolysis of the silane coupling agent, but also inhibit the condensation reaction of the silane coupling agent itself, thereby extending the service life of the hydrolyzate of the silane coupling agent.

[0052] Optionally, the general formula of the silane coupling agent is R 1 -Si-(OR 2 ) 3 , where -R 1 is an alkyl group or an isomer of an alkyl group, such as methyl, ethyl, propyl, n-butyl, isobutyl, etc., and the number of carbon atoms is preferably 1-12, -OR 2 It is a hydrolyzable group, such as ethoxy, methoxy, propoxy, etc.

[0053] In order to ensure that the silane coupling agent occupies a more sufficient position on the surface of the first silica particles and the hydroxyl groups on the surface of the first silica particles are completely reacted, the amount of the silane coupling agent is preferably 1 wt%-20 wt% of the solid content in the first reaction product.

[0054] Since the hydroxyl groups on the surface of the first silica particles have been completely reacted in step S3, when the second silicon source is added in step S4, the newly added second silicon source will form new cores. Since the new cores have a higher specific surface energy, the second silicon sources subsequently added in batches will continue to grow on the new cores to obtain the target small-sized second silica particles, while maintaining the particle size of the first silica particles basically unchanged.

[0055] Similarly, before adding the second silicon source to the second reaction product in batches for reaction, the second reaction product is first heated to 50°C-90°C by heating in a water bath or the like, and then the second silicon source is added to the second reaction product in batches, wherein the second silicon source is selected from at least one of methyl orthosilicate, ethyl orthosilicate, propyl orthosilicate, butyl orthosilicate, sodium silicate and potassium silicate, and the batch addition is carried out dropwise, etc. When dropwise addition is adopted, it can be continuous dropwise addition or intermittent dropwise addition.

[0056] Similarly, by adjusting the addition rate of the second silicon source, the particle size of the generated second silicon dioxide particles can also be adjusted. Therefore, the addition rate of the second silicon source can be adjusted according to the target particle size of the second silicon dioxide particles in the dual-particle silica sol. Preferably, the time for adding the second silicon source in batches is preferably 2h-6h.

[0057] In order to make the particle size of the second silicon dioxide particles generated by the reaction more uniform, it is preferred that when the second silicon source is added to the second reaction product in batches for reaction, the temperature fluctuates within 5° C., more preferably in a constant temperature state.

[0058] It should be noted that when the hydrolyzate of the silane coupling agent is mixed with the first reaction product for reaction in step S3, there is basically no effect on the pH. Optionally, before adding the second silicon source to the second reaction product in batches for reaction, an alkaline catalyst can be used to adjust the pH to maintain the pH at 9-12.

[0059] Therefore, the present invention obtains a double-particle-size silica sol by growing a second silica particle with a small particle size through secondary nucleation, rather than by increasing the particle size of some silica particles. This makes it possible to accurately control the proportion of particles with two different particle sizes, and the particle sizes of the two particles in the double-particle-size silica sol are uniform, stable and highly dispersed.

[0060] Based on this, the present invention also provides a double-particle-size silica sol obtained by the preparation method, wherein the double-particle-size silica sol includes a first silica particle and a second silica particle, the particle size of the first silica particle is larger than the particle size of the second silica particle, and the particle sizes of the two particles are uniform, stable and highly dispersed.

[0061] The dual-particle size silica sol of the present invention can be widely used in the fields of chemical mechanical polishing and optical polyester film preparation. When used, the particle sizes and proportions of the two particles can be accurately controlled during preparation as needed.

[0062] Specifically, the present invention also provides an application of the dual-particle silica sol in a polishing liquid. When used, the particle size of the first silica particles in the dual-particle silica sol is 80nm-200nm, the particle size of the second silica particles is 10nm-60nm, and the mass ratio of the first silica particles to the second silica particles is 1:1-4:1. Thus, by controlling the particle size and proportion of the two particles, the requirements of polishing rate and surface quality can be met at the same time.

[0063] Hereinafter, the dual-particle silica sol and its preparation method and application will be further described through the following specific examples.

[0064] Example 1

[0065] 750.00 g of ethanol and 250.00 g of deionized water were mixed to prepare an alcohol aqueous solution, and then the pH was adjusted with aqueous ammonia to obtain a mother liquor with a pH of 11.50.

[0066] Turn on mechanical stirring at a speed of 400 rpm, heat the mother liquor in a water bath to 85°C, and after the temperature stabilizes, add 218.50 g of tetraethoxysilane dropwise for 24 hours. After the addition is complete, age for 1 hour to obtain a first reaction product, which includes first silica particles with a particle size of 90 nm and a solid content of 5%.

[0067] Deionized water and ethanol were prepared into 98.00 mL of solution in a volume ratio of 1:3, and then the pH was adjusted with hydrochloric acid to obtain a mixed solution with a pH of 4. Then 2.00 g of propyltrimethoxysiloxane was added to the mixed solution, and the mixture was slowly stirred at 200 rpm for 3 hours. After the hydrolysis was completed, a hydrolyzate of the silane coupling agent was obtained.

[0068] The first reaction product was mixed with the hydrolyzate of the silane coupling agent and reacted at 80° C. for 3 hours to obtain a second reaction product.

[0069] Then, 21.85 g of tetraethoxysilane was added dropwise to the second reaction product for 2 h. After the addition was completed, the product was aged for 1 h to obtain a double-particle silica sol.

[0070] like Figure 1 As shown, in the double-particle-size silica sol obtained in this embodiment, the silica particles are distributed in double particle sizes and have high dispersion. After testing, in the double-particle-size silica sol, the particle size of the first silica particles is 90 nm, and the particle size of the second silica particles is 20 nm, wherein the mass ratio of the first silica particles to the second silica particles is 10:1, and the zeta potential of the double-particle-size silica sol is -35.97 mV and the PDI is 0.017.

[0071] Example 2

[0072] 750.00 g of ethanol and 250.00 g of deionized water were mixed to prepare an alcohol aqueous solution, and then the pH was adjusted with aqueous ammonia to obtain a mother liquor with a pH of 11.50.

[0073] Turn on mechanical stirring at a speed of 400 rpm, heat the mother liquor in a water bath to 85°C, and after the temperature stabilizes, add 218.50 g of tetraethoxysilane dropwise for 24 hours. After the addition is complete, age for 1 hour to obtain a first reaction product, which includes first silica particles with a particle size of 90 nm and a solid content of 5%.

[0074] Deionized water and ethanol were prepared into 98.00 mL of solution in a volume ratio of 1:3, and then the pH was adjusted with hydrochloric acid to obtain a mixed solution with a pH of 4. Then 2.00 g of propyltrimethoxysiloxane was added to the mixed solution, and the mixture was slowly stirred at 200 rpm for 3 hours. After the hydrolysis was completed, a hydrolyzate of the silane coupling agent was obtained.

[0075] The first reaction product was mixed with the hydrolyzate of the silane coupling agent and reacted at 80° C. for 3 hours to obtain a second reaction product.

[0076] Then, 43.70 g of tetraethoxysilane was added dropwise to the second reaction product for 4 hours. After the addition was completed, the product was aged for 1 hour to obtain a double-particle silica sol.

[0077] like Figure 2 As shown, in the double-particle-size silica sol obtained in this embodiment, the silica particles are distributed in double particle sizes and have high dispersion. After testing, in the double-particle-size silica sol, the particle size of the first silica particles is 90 nm, and the particle size of the second silica particles is 20 nm, wherein the mass ratio of the first silica particles to the second silica particles is 5:1, and the zeta potential of the double-particle-size silica sol is -37.00 mV and the PDI is 0.020.

[0078] Example 3

[0079] 750.00 g of ethanol and 250.00 g of deionized water were mixed to prepare an alcohol aqueous solution, and then the pH was adjusted with aqueous ammonia to obtain a mother liquor with a pH of 11.50.

[0080] Turn on mechanical stirring at a speed of 400 rpm, heat the mother liquor in a water bath to 85°C, and after the temperature stabilizes, add 218.50 g of tetraethoxysilane dropwise for 24 hours. After the addition is complete, age for 1 hour to obtain a first reaction product, which includes first silica particles with a particle size of 90 nm and a solid content of 5%.

[0081] Deionized water and ethanol were prepared into 98.00 mL of solution in a volume ratio of 1:3, and then the pH was adjusted with hydrochloric acid to obtain a mixed solution with a pH of 4. Then 2.00 g of propyltrimethoxysiloxane was added to the mixed solution, and the mixture was slowly stirred at 200 rpm for 3 hours. After the hydrolysis was completed, a hydrolyzate of the silane coupling agent was obtained.

[0082] The first reaction product was mixed with the hydrolyzate of the silane coupling agent and reacted at 80° C. for 3 hours to obtain a second reaction product.

[0083] Then, 65.55 g of tetraethoxysilane was added dropwise to the second reaction product for 4 hours. After the addition was completed, the product was aged for 1 hour to obtain a double-particle silica sol.

[0084] like Figure 3 As shown, in the double-particle-size silica sol obtained in this embodiment, the silica particles are distributed in double particle sizes and have high dispersion. After testing, in the double-particle-size silica sol, the particle size of the first silica particles is 90 nm, and the particle size of the second silica particles is 20 nm, wherein the mass ratio of the first silica particles to the second silica particles is 10:3, and the zeta potential of the double-particle-size silica sol is -36.55 mV and the PDI is 0.018.

[0085] Example 4

[0086] 750.00 g of ethanol and 250.00 g of deionized water were mixed into an alcohol aqueous solution, and then the pH was adjusted with potassium hydroxide to obtain a mother liquor with a pH of 11.50.

[0087] Turn on mechanical stirring at a speed of 400 rpm, heat the mother liquor in a water bath to 90°C, and after the temperature stabilizes, add 290.88 g of tetrapropoxysilane dropwise for 15 hours. After the addition is complete, age for 1 hour to obtain a first reaction product, which includes first silica particles with a particle size of 120 nm and a solid content of 5%.

[0088] Deionized water and ethanol were prepared into 73.50 mL of solution in a volume ratio of 1:3, and then the pH was adjusted with hydrochloric acid to obtain a mixed solution with a pH of 4. Then 1.50 g of n-butyltrimethoxysiloxane was added to the mixed solution, and the mixture was slowly stirred at 200 rpm for 3 hours. After the hydrolysis was completed, a hydrolyzate of the silane coupling agent was obtained.

[0089] The first reaction product was mixed with the hydrolyzate of the silane coupling agent and reacted at 90° C. for 3 hours to obtain a second reaction product.

[0090] Then, 116.35 g of tetrapropoxysilane was added dropwise to the second reaction product for 4 hours. After the addition was completed, the product was aged for 1 hour to obtain a double-particle silica sol.

[0091] After testing, in the dual-particle silica sol, the particle size of the first silica particles is 120nm, and the particle size of the second silica particles is 40nm, wherein the mass ratio of the first silica particles to the second silica particles is 5:2, and the zeta potential of the dual-particle silica sol is -40.06mV and the PDI is 0.020.

[0092] Example 5

[0093] 750.00 g of ethanol and 250.00 g of deionized water were mixed into an alcohol aqueous solution, and then the pH was adjusted with potassium hydroxide to obtain a mother liquor with a pH of 11.50.

[0094] Turn on mechanical stirring at a speed of 400 rpm, heat the mother liquor in a water bath to 90°C, and after the temperature stabilizes, add 290.88 g of tetrapropoxysilane dropwise for 24 hours. After the addition is complete, age for 1 hour to obtain a first reaction product, which includes first silica particles with a particle size of 140 nm and a solid content of 5%.

[0095] Deionized water and ethanol were mixed in a volume ratio of 1:3 to prepare 59.29 mL of a solution, and the pH was adjusted with hydrochloric acid to obtain a mixed solution with a pH of 4. Then, 1.21 g of n-butyltrimethoxysiloxane was added to the mixed solution, and the mixture was slowly stirred at 200 rpm for 3 hours. After the hydrolysis was completed, a hydrolyzate of the silane coupling agent was obtained.

[0096] The first reaction product was mixed with the hydrolyzate of the silane coupling agent and reacted at 90° C. for 3 hours to obtain a second reaction product.

[0097] Then, 116.35 g of tetrapropoxysilane was added dropwise to the second reaction product for 6 hours. After the addition was completed, the product was aged for 1 hour to obtain a double-particle silica sol.

[0098] After testing, in the dual-particle silica sol, the particle size of the first silica particles is 140nm, and the particle size of the second silica particles is 50nm, wherein the mass ratio of the first silica particles to the second silica particles is 5:2, and the zeta potential of the dual-particle silica sol is -36.48mV and the PDI is 0.025.

[0099] Example 6

[0100] 750.00 g of ethanol and 250.00 g of deionized water were mixed to prepare an alcohol aqueous solution, and then the pH was adjusted with aqueous ammonia to obtain a mother liquor with a pH of 11.50.

[0101] Turn on mechanical stirring at a speed of 400 rpm, heat the mother liquor in a water bath to 85°C, and after the temperature stabilizes, add 218.50 g of tetraethoxysilane dropwise for 24 hours. After the addition is complete, age for 1 hour to obtain a first reaction product, which includes first silica particles with a particle size of 90 nm and a solid content of 5%.

[0102] Deionized water and ethanol were prepared into 98.00 mL of solution in a volume ratio of 1:3, and then the pH was adjusted with hydrochloric acid to obtain a mixed solution with a pH of 4. Then 2.00 g of propyltrimethoxysiloxane was added to the mixed solution, and the mixture was slowly stirred at 200 rpm for 3 hours. After the hydrolysis was completed, a hydrolyzate of the silane coupling agent was obtained.

[0103] The first reaction product was mixed with the hydrolyzate of the silane coupling agent and reacted at 80° C. for 3 hours to obtain a second reaction product.

[0104] Then, 655.50 g of tetraethoxysilane was added dropwise to the second reaction product for 4 hours. After the addition was completed, the product was aged for 1 hour to obtain a double-particle silica sol.

[0105] In the double-particle-size silica sol obtained in this example, the silica particles are distributed in double particle sizes and have high dispersion. According to the test, in the double-particle-size silica sol, the particle size of the first silica particle is 90 nm, and the particle size of the second silica particle is 20 nm, wherein the mass ratio of the first silica particle to the second silica particle is 1:3, and the zeta potential of the double-particle-size silica sol is -37.19 mV and the PDI is 0.114.

[0106] Comparative Example 1

[0107] 750.00 g of ethanol and 250.00 g of deionized water were mixed to prepare an alcohol aqueous solution, and then the pH was adjusted with aqueous ammonia to obtain a mother liquor with a pH of 11.50.

[0108] Turn on mechanical stirring at a speed of 400 rpm, heat the mother liquor in a water bath to 85°C, and after the temperature stabilizes, add 218.50 g of tetraethoxysilane dropwise for 24 hours. After the addition is complete, age for 1 hour to obtain a first reaction product, which includes silicon dioxide particles with a particle size of 90 nm and a solid content of 5%.

[0109] Then, 21.85 g of tetraethoxysilane was added dropwise to the first reaction product for 4 h. After the addition was completed, the mixture was aged for 1 h to obtain the following: Figure 4 The silica sol shown is a single-size particle.

[0110] Comparative Example 2

[0111] 750.00 g of ethanol and 250.00 g of deionized water were mixed to prepare an alcohol aqueous solution, and then the pH was adjusted with aqueous ammonia to obtain a mother liquor with a pH of 11.50.

[0112] Turn on mechanical stirring at a speed of 400 rpm, heat the mother liquor in a water bath to 80°C, and after the temperature stabilizes, add 218.50 g of tetraethoxysilane dropwise for 4 hours. After the addition is complete, age for 1 hour to obtain a first reaction product, which includes first silica particles with a particle size of 20 nm and a solid content of 5%.

[0113] Deionized water and ethanol were prepared into 97.75 mL of solution in a volume ratio of 1:3, and then the pH was adjusted with hydrochloric acid to obtain a mixed solution with a pH of 4. Then 8.50 g of propyltrimethoxysiloxane was added to the mixed solution, and the mixture was slowly stirred at 200 rpm for 3 hours. After the hydrolysis was completed, a hydrolyzate of the silane coupling agent was obtained.

[0114] The first reaction product was mixed with the hydrolyzate of the silane coupling agent and reacted at 80° C. for 3 hours to obtain a second reaction product.

[0115] Then, 218.50 g of tetraethoxysilane was added dropwise to the second reaction product for 4 hours. After the addition was completed, the mixture was aged for 1 hour.

[0116] After testing, the product was found to have a single particle size distribution of about 27 nm, and failed to form a double particle size distribution.

[0117] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0118] The above-mentioned embodiments only express several implementation methods of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A method for preparing a double-particle size silica sol, characterized in that: The following steps are involved: Prepare an alcohol-water solvent, and then use an alkaline catalyst to adjust the pH to obtain a mother solution with a pH of 9-12; Adding a first silicon source to the mother solution in batches for reaction to grow first silicon dioxide particles, and obtaining a first reaction product after the reaction is completed; The first reaction product is mixed with a hydrolyzate of a silane coupling agent to react, and after the reaction is completed, a second reaction product is obtained; A second silicon source is added to the second reaction product in batches for reaction to grow second silicon dioxide particles. After the reaction is completed, a double-particle-size silica sol is obtained, wherein the particle size of the first silicon dioxide particles is larger than that of the second silicon dioxide particles.

2. The method for preparing the double-particle-size silica sol according to claim 1, characterized in that: The first silicon source and the second silicon source are independently selected from at least one of methyl orthosilicate, ethyl orthosilicate, propyl orthosilicate, butyl orthosilicate, sodium silicate and potassium silicate.

3. The method for preparing the double-particle silica sol according to claim 1, characterized in that: The step of adding the first silicon source to the mother liquor in batches to react satisfies at least one of the following conditions: (1) The temperature of the mother liquor is 50° C.-90° C.; (2) The temperature fluctuation during the reaction is within 5°C; (3) The time for adding the first silicon source in batches is 4h-24h.

4. The method for preparing the double-particle silica sol according to claim 1, characterized in that: The solid content of the first reaction product is 5%-10%.

5. The method for preparing the double-particle silica sol according to claim 1, characterized in that: The step of mixing the first reaction product with the hydrolyzate of the silane coupling agent to react satisfies at least one of the following conditions: (1) The general formula of the silane coupling agent is R1-Si-(OR2)3, wherein -R1 is an alkyl group or an isomer of an alkyl group, the number of carbon atoms is 1-12, and -OR2 is a hydrolyzable group; (2) The amount of the silane coupling agent is 1%-20wt% of the solid content in the first reaction product; (3) The reaction temperature is 25°C-95°C and the reaction time is 0.5h-4h.

6. The method for preparing the double-particle silica sol according to claim 1 or 5, characterized in that: The preparation method of the hydrolyzate of the silane coupling agent comprises the following steps: Prepare an alcohol-water solvent, and then use an acid catalyst to adjust the pH to 1-5 to obtain a mixed solution; A silane coupling agent is added to the mixed solution, and the mixed solution is hydrolyzed to obtain a hydrolyzed solution of the silane coupling agent.

7. The method for preparing the double-particle silica sol according to claim 1, characterized in that: The step of adding the second silicon source to the second reaction product in batches to react satisfies at least one of the following conditions: (1) The temperature of the second reaction product is 50° C.-90° C.; (2) The temperature fluctuation during the reaction is within 5°C; (3) The time for adding the second silicon source in batches is 2h-6h.

8. A double-particle silica sol obtained by the preparation method according to any one of claims 1 to 7.

9. Use of the double-particle silica sol as claimed in claim 8 in a polishing liquid.

10. The use of the double-particle silica sol in a polishing liquid according to claim 9, characterized in that: In the dual-particle silica sol, the particle size of the first silica particles is 80nm-200nm, the particle size of the second silica particles is 10nm-60nm, and the mass ratio of the first silica particles to the second silica particles is 1:1-4:1.

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