Preparation method of nano silicon dioxide particles

Abstract

The invention provides a preparation method of nano silicon dioxide particles, which comprises the following steps: (1) dissolving alkoxy silane in an organic solvent 1, and uniformly mixing to obtain a solution A with the density of rho; (2) uniformly mixing ammonia water and an organic solvent 2 to obtain a solution B; and (3) heating the solution B to T, and then adding the solution A for reaction to obtain the nano silicon dioxide particles, wherein rho is larger than or equal to 0.890 g / cm < 3 > and smaller than or equal to 0.910 g / cm < 3 >, and rho and T meet the following relational expression that T is larger than or equal to 22 rho and According to the preparation method disclosed by the invention, by optimizing a synthesis route, particularly by controlling the density of the silane solution and the reaction temperature under the corresponding density, the particle size and the particle size uniformity of the nano silicon dioxide particles can be effectively controlled, and the small-particle-size (less than 100nm) nano silicon dioxide particles with relatively high particle size uniformity are prepared.

Description

Technical Field

[0001] The invention belongs to the technical field of chemical synthesis, and in particular relates to a method for preparing nano silicon dioxide particles. Background Art

[0002] Nano-scale silica aqueous solution is also commonly called silica sol. Silica sol has a wide range of uses. It is widely used in the coating industry because of its easy film formation, good water resistance and heat resistance. At the same time, silica sol can also be used to prepare polishing liquid for chemical mechanical polishing process of semiconductor integrated circuits, but this type of silica sol has strict control over organic impurities, metal ions, etc. in silica sol, and also has specific requirements for the shape, particle size and degree of association of silica nanoparticles.

[0003] At present, silica sol is generally prepared by sodium silicate through ion exchange, and the process route is relatively mature. However, the sodium silicate ion exchange method contains a large amount of sodium ions in the raw materials, and the cost of removing them in the later stage is high; at the same time, the introduction of organic impurities brought by the ion column is inevitable, which also brings new challenges to the later treatment.

[0004] Werner Stober and others used tetraethyl orthosilicate in combination with ethanol solvent, and successfully prepared spherical silica particles under the catalysis of ammonia water. The raw materials such as alcohol and ammonia used in this method, as well as the product alcohol, are substances with a large difference in boiling point from water, and are likely to be removed later. However, the particle size of silica particles prepared using this method is usually above 200nm. When preparing small-sized silica particles below 100nm, due to the activity of the reactants, even if small silica particles with a particle size of less than 100nm can be prepared, the uniformity of the particle size is poor. Summary of the invention

[0005] Based on this, the object of the present invention is to provide a method for preparing nano-silicon dioxide particles, which can prepare silicon dioxide particles with a particle size of less than 100 nm and uniform size.

[0006] To achieve the above object, the present invention adopts the following technical solution.

[0007] A method for preparing nano-silicon dioxide particles comprises the following steps: (1) dissolving alkoxysilane in an organic solvent 1 and mixing them uniformly to obtain a solution A with a density of ρ; (2) mixing ammonia water and an organic solvent 2 uniformly to obtain a solution B; (3) heating the solution B to T, then adding the solution A to react, and obtaining the nano-silicon dioxide particles;

[0008] Among them, 0.890g / cm 3 ≤ρ≤0.910g / cm 3, and ρ and T satisfy the following relationship: 22ρ≤T≤35ρ.

[0009] In some embodiments, 0.890 g / cm 3 ≤ρ≤0.905g / cm 3 .

[0010] In some embodiments, the mass fraction of the aqueous ammonia is 30% to 50%.

[0011] In some embodiments, the mass ratio of the aqueous ammonia to the organic solvent 2 is 1:2-6.

[0012] In some embodiments, the reaction temperature in step (3) is required to satisfy 22ρ≤T≤35ρ.

[0013] In some embodiments, the reaction time in step (3) is 2 h to 6 h.

[0014] In some embodiments, the addition rate of solution A in step (3) is 1 ml / min to 5 ml / min.

[0015] In some embodiments, the step (3) further comprises distilling the reaction product of the solution B and the solution A under reduced pressure.

[0016] In some embodiments, the alkoxysilane is selected from one or more of tetramethoxysilane, tetraethoxysilane, tetra-n-butoxysilane, methyltriethoxysilane, dimethyldimethoxysilane, dimethylethoxysilane, ethoxytriethylsilane, and trimethylethoxysilane.

[0017] Preferably, the alkoxysilane is selected from one or more of tetramethoxysilane and tetraethoxysilane.

[0018] In some embodiments, the organic solvent 1 and the organic solvent 2 are independently selected from one or more of methanol, ethanol, isopropanol, ethylene glycol, n-butanol, and isobutanol.

[0019] Preferably, the organic solvent 1 and the organic solvent 2 are the same.

[0020] The present invention provides a method for preparing nano-silicon dioxide particles, which can prepare silicon dioxide particles with a particle size of less than 100 nm and uniform size. The inventors have found through research that in the reaction system of the present invention, by controlling the density ρ of the silane solution to 0.890 g / cm 3 ≤ρ≤0.910g / cm 3, and the subsequent hydrolysis reaction temperature T is controlled to meet 22ρ≤T≤35ρ at this density, which can effectively adjust the particle size and particle size uniformity of the nano-silica particles obtained by the reaction. The inventors have found through research that when the density of the silane solution meets a specific range, by adjusting the reaction temperature, the nucleation and seed nucleus growth reactions of the nano-silica particles can be effectively controlled, avoiding problems such as uneven seed nucleation growth caused by uneven nucleation, poor particle size uniformity, and excessive growth particle size, thereby ensuring the particle size and particle size uniformity of the nano-silica particles. DETAILED DESCRIPTION

[0021] The experimental methods in the following examples of the present invention, where no specific conditions are specified, are usually carried out under conventional conditions or under conditions recommended by the manufacturers. The various commonly used chemical reagents used in the examples are all commercially available products.

[0022] Unless otherwise defined, all technical and scientific terms used in the present invention have the same meaning as those commonly understood by those skilled in the art of the present invention. The terms used in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention.

[0023] The terms "including" and "having" and any variations thereof of the present invention are intended to cover non-exclusive inclusions. For example, a process, method, device, product or equipment comprising a series of steps is not limited to the listed steps or modules, but may optionally include steps not listed, or may optionally include other steps inherent to these processes, methods, products or equipment.

[0024] In the present invention, the term "multiple" refers to two or more than two. "And / or" describes the association relationship of associated objects, indicating that three relationships may exist. For example, A and / or B can represent the following three situations: A exists alone, A and B exist at the same time, and B exists alone. The character " / " generally indicates that the associated objects are in an "or" relationship.

[0025] The following describes the invention in conjunction with specific embodiments.

[0026] Example 1

[0027] This embodiment provides a method for preparing a solution (silica sol) containing nano-silicon dioxide particles, and the preparation method comprises the following steps:

[0028] (1) dissolving 5 g of tetramethoxysilane in 15 g of methanol and mixing well to obtain solution A;

[0029] (2) 15 g of 30 wt% aqueous ammonia and 60 g of methanol were mixed to obtain solution B;

[0030] (3) heating the solution B to 25° C., then adding the solution A at a rate of 2 ml / min, and reacting for 4 h to obtain a crude silica sol;

[0031] (4) The crude silica sol is subjected to vacuum distillation and alcohol exchange operations to obtain the silica sol: the crude silica sol is subjected to vacuum distillation to remove most of the organic solvent and ammonia while concentrating. After the solid content of the system is concentrated to 15%, vacuum distillation is continued under the operation of continuous water replenishment to remove the remaining alcohol and ammonia in the system.

[0032] Example 2

[0033] This embodiment provides a method for preparing a solution (silica sol) containing nano-silicon dioxide particles, and the preparation method comprises the following steps:

[0034] (1) dissolving 5 g of tetramethoxysilane in 10 g of methanol and mixing well to obtain solution A;

[0035] (2) 15 g of 30 wt% aqueous ammonia and 60 g of methanol were mixed to obtain solution B;

[0036] (3) heating the solution B to 25° C., then adding the solution A at a rate of 2 ml / min, and reacting for 4 h to obtain a crude silica sol;

[0037] (4) The crude silica sol is subjected to vacuum distillation and alcohol exchange operations to obtain the silica sol: the crude silica sol is subjected to vacuum distillation to remove most of the organic solvent and ammonia while concentrating. After the solid content of the system is concentrated to 15%, vacuum distillation is continued under the operation of continuous water replenishment to remove the remaining alcohol and ammonia in the system.

[0038] Example 3

[0039] This embodiment provides a method for preparing a solution (silica sol) containing nano-silicon dioxide particles, and the preparation method comprises the following steps:

[0040] (1) dissolving 5 g of tetramethoxysilane in 20 g of methanol and mixing well to obtain solution A;

[0041] (2) 15 g of 30 wt% aqueous ammonia and 60 g of methanol were mixed to obtain solution B;

[0042] (3) heating the solution B to 25° C., then adding the solution A at a rate of 2 ml / min, and reacting for 4 h to obtain a crude silica sol;

[0043] (4) The crude silica sol is subjected to vacuum distillation and alcohol exchange operations to obtain the silica sol: the crude silica sol is subjected to vacuum distillation to remove most of the organic solvent and ammonia while concentrating. After the solid content of the system is concentrated to 15%, vacuum distillation is continued under the operation of continuous water replenishment to remove the remaining alcohol and ammonia in the system.

[0044] Example 4

[0045] This embodiment provides a method for preparing a solution (silica sol) containing nano-silicon dioxide particles, and the preparation method comprises the following steps:

[0046] (1) dissolving 5 g of tetramethoxysilane in 15 g of methanol and mixing well to obtain solution A;

[0047] (2) 15 g of 30 wt% aqueous ammonia and 60 g of methanol were mixed to obtain solution B;

[0048] (3) heating the solution B to 22° C., then adding the solution A at a rate of 2 ml / min, and reacting for 4 h to obtain a crude silica sol;

[0049] (4) The crude silica sol is subjected to vacuum distillation and alcohol exchange operations to obtain the silica sol: the crude silica sol is subjected to vacuum distillation to remove most of the organic solvent and ammonia while concentrating. After the solid content of the system is concentrated to 15%, vacuum distillation is continued under the operation of continuous water replenishment to remove the remaining alcohol and ammonia in the system.

[0050] Example 5

[0051] This embodiment provides a method for preparing a solution (silica sol) containing nano-silicon dioxide particles, and the preparation method comprises the following steps:

[0052] (1) dissolving 5 g of tetramethoxysilane in 15 g of methanol and mixing well to obtain solution A;

[0053] (2) 15 g of 50 wt% aqueous ammonia and 60 g of methanol were mixed to obtain solution B;

[0054] (3) heating the solution B to 30° C., then adding the solution A at a rate of 2 ml / min, and reacting for 4 h to obtain a crude silica sol;

[0055] (4) The crude silica sol is subjected to vacuum distillation and alcohol exchange operations to obtain the silica sol: the crude silica sol is subjected to vacuum distillation to remove most of the organic solvent and ammonia while concentrating. After the solid content of the system is concentrated to 15%, vacuum distillation is continued under the operation of continuous water replenishment to remove the remaining alcohol and ammonia in the system.

[0056] Comparative Examples 1 to 5

[0057] Comparative Examples 1 to 5 respectively provide a method for preparing a solution (silica sol) containing nano-silica particles. The preparation method includes most of the operations in Example 1, except for the amounts of alkoxysilane and organic solvent 1, as shown in Table 1 for details.

[0058] The particle size and particle size uniformity of the nano-silicon dioxide particles prepared in the above examples and comparative examples were tested. The particle size test and particle size uniformity characterization were performed using the Z-average particle size and PDI results of a dynamic light scattering tester. The results are entered in Table 2.

[0059] Table 1

[0060]

[0061]

[0062] Table 2

[0063]

[0064] Note: When the Z-average particle size is less than 100 nm and PDI is less than 0.1, the result is OK; when the Z-average particle size is greater than or equal to 100 nm and / or PDI is greater than or equal to 0.1, the result is NG.

[0065] The above results show that the particle size of the nano-silicon dioxide particles in the solution prepared by the method of the present invention (Examples 1 to 5) is less than 100 nm, PDI < 0.1, the particle size and uniformity are good, and can meet the requirements of preparing polishing liquid for the chemical mechanical polishing process of semiconductor integrated circuits.

[0066] Compared with Example 1, T<22ρ in Comparative Example 1 and T>35ρ in Comparative Example 2 both result in the particle size of the nano-silicon dioxide particles in the solution being greater than 100 nm and PDI>0.1, which do not meet the requirements.

[0067] Compared with Example 1, the density ρ of solution A in Comparative Examples 3 and 4 is too low, and the density ρ of solution A in Comparative Example 5 is too high, both of which result in that the particle size and uniformity of the nano-silica particles in the solution cannot meet the requirements.

[0068] In summary, the preparation method of the present invention can be optimized, especially by controlling the density of the silane solution and the reaction temperature at the corresponding density, to prepare silicon dioxide particles with a particle size of less than 100 nm and uniform particle size.

[0069] 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 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.

[0070] The above-mentioned embodiments only express several implementation methods of the present invention, and the description thereof is relatively specific and detailed, but it cannot be understood as limiting the scope of the patent of the present invention. 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, which 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 nano silicon dioxide particles, characterized in that: The method comprises the following steps: (1) dissolving alkoxysilane in an organic solvent 1 and mixing them uniformly to obtain a solution A with a density of ρ; (2) mixing ammonia water and an organic solvent 2 uniformly to obtain a solution B; (3) heating the solution B to T, and then adding the solution A to react to obtain the nano-silicon dioxide particles; Among them, 0.890g / cm 3 ≤ρ≤0.910g / cm 3 , and ρ and T satisfy the following relationship: 22ρ≤T≤35ρ.

2. The preparation method according to claim 1, characterized in that 0.890g / cm 3 ≤ρ≤0.905g / cm 3 。 3. The preparation method according to claim 1, characterized in that: The mass fraction of the ammonia water is 30% to 50%.

4. The preparation method according to claim 3, characterized in that: The mass ratio of the ammonia water to the organic solvent 2 is 1:2-6.

5. The preparation method according to claim 1, characterized in that: The reaction time in step (3) is 2 h to 6 h.

6. The preparation method according to claim 1, characterized in that: The addition rate of solution A in step (3) is 1 ml / min to 5 ml / min.

7. The preparation method according to claim 1, characterized in that: The step (3) further comprises distilling the reaction product of the solution B and the solution A under reduced pressure.

8. The preparation method according to any one of claims 1 to 7, characterized in that: The alkoxysilane is selected from one or more of tetramethoxysilane, tetraethoxysilane, tetra-n-butoxysilane, methyltriethoxysilane, dimethyldimethoxysilane, dimethylethoxysilane, ethoxytriethylsilane and trimethylethoxysilane.

9. The preparation method according to claim 8, characterized in that: The alkoxysilane is selected from one or more of tetramethoxysilane and tetraethoxysilane.

10. The preparation method according to any one of claims 1 to 7, characterized in that: The organic solvent 1 and the organic solvent 2 are independently selected from one or more of methanol, ethanol, isopropanol, ethylene glycol, n-butanol and isobutanol.

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