Method for producing a dispersion containing colloidal silica particles

Abstract

The present invention provides a method for producing a dispersion containing colloidal silica particles that can reduce the content of by-products generated by hydrogen peroxide. [Solution] A method for producing a dispersion containing colloidal silica particles, comprising an ion exchange step of contacting a liquid containing colloidal silica particles and hydrogen peroxide with an ion exchange resin.

Description

Technical Field

[0001] The present invention relates to a method for producing a dispersion containing colloidal silica particles. Background Art

[0002] Conventionally, chemical mechanical polishing (CMP) using a polishing composition has been performed on the surface of materials such as metals, semimetals, nonmetals, and oxides thereof. This polishing composition generally has a configuration in which an aqueous solution having a chemical polishing action and particles (abrasive grains) having a mechanical polishing action are mixed and dispersed, and it is known to use colloidal silica particles as the abrasive grains.

[0003] In the production process of a dispersion containing colloidal silica particles, hydrogen peroxide is added to the dispersion to enhance the antifungal effect. Further, Patent Document 1 discloses a method for producing a silica sol, which includes a step of hydrolyzing and condensing tetraalkoxysilane to obtain a silica sol reaction liquid and a step of adding an oxidizing agent containing hydrogen peroxide to the silica sol reaction liquid, so as to reduce intermediate products in the production process of colloidal silica (silica sol). Prior Art Documents Patent Documents

[0004] Patent Document 1 JP 2020-075830 A Summary of Invention Problems to be Solved by the Invention

[0005] Hydrogen peroxide used in the production process of dispersions containing colloidal silica particles, the production process of colloidal silica, and the like has a problem that it reacts with residues of components used in the production process (for example, organic solvents such as methanol) to generate by-products.

[0006] Therefore, the present invention aims to provide a method for producing a dispersion containing colloidal silica particles that can reduce the content of by-products generated by hydrogen peroxide. [Means for solving the problem]

[0007] In view of the above problems, the inventors diligently conducted research. As a result, they found that the above problems can be solved by a method for producing a dispersion containing colloidal silica particles, which includes an ion exchange step of contacting a liquid containing colloidal silica particles and hydrogen peroxide with an ion exchange resin, and thus completed the present invention. [Effects of the Invention]

[0008] The present invention provides a method for producing a dispersion containing colloidal silica particles that can reduce the content of by-products generated by hydrogen peroxide. [Modes for carrying out the invention]

[0009] The following describes an embodiment of one part of the present invention. However, the present invention is not limited to the following embodiments.

[0010] In this specification, the range "X~Y" means "X or greater and Y or less". Unless otherwise specified, operations and measurements of physical properties are performed under room temperature (20~25°C) / relative humidity 40~50%RH conditions.

[0011] <Method for producing a dispersion containing colloidal silica particles> One aspect of the present invention is a method for producing a dispersion containing colloidal silica particles, comprising an ion exchange step of contacting a liquid containing colloidal silica particles and hydrogen peroxide with an ion exchange resin. The method for producing a dispersion containing colloidal silica particles according to this aspect can reduce by-products generated by hydrogen peroxide.

[0012] [Ion exchange process] The method for producing a dispersion containing colloidal silica particles according to this embodiment includes an ion exchange step in which a liquid containing colloidal silica particles and hydrogen peroxide is brought into contact with an ion exchange resin.

[0013] The ion exchange process may be performed once, or two or more times as needed.

[0014] In this specification, "a liquid containing colloidal silica particles and hydrogen peroxide" is also simply referred to as "the liquid according to this embodiment."

[0015] The liquid according to this embodiment contains colloidal silica particles. The colloidal silica particles may be colloidal silica particles produced by the alkoxide method or colloidal silica particles produced by the sodium silicate method. From the viewpoint of reducing metal impurities, the colloidal silica particles are preferably colloidal silica particles produced by the alkoxide method.

[0016] The alkoxide method typically involves using alkoxysilanes as raw materials and performing a hydrolysis condensation reaction. One example of the alkoxide method is a method in which colloidal silica (a raw material solution containing colloidal silica particles) is synthesized by reacting alkoxysilanes or their condensates with water in a reaction solution containing an alkaline catalyst, in the presence of the alkaline catalyst.

[0017] The alkoxysilane or its condensate is not particularly limited and known alkoxysilanes can be used. The alkoxysilane condensate is, for example, 2 to 12-mers, preferably 4 to 8-mers. Examples of alkoxysilanes include tetramethoxysilane, tetraethoxysilane, and tetrapropoxysilane. From the viewpoint of having appropriate hydrolysis reactivity, tetramethoxysilane is preferred. The alkoxysilane or its condensate may be used alone or in combination of two or more types.

[0018] From the viewpoint of minimizing the inclusion of metal impurities and other contaminants, it is preferable to use pure water or ultrapure water.

[0019] As the organic solvent, a hydrophilic organic solvent is preferred. Specifically, examples include alcohols such as methanol, ethanol, n-propanol, isopropanol, ethylene glycol, propylene glycol, and 1,4-butanediol; and ketones such as acetone and methyl ethyl ketone. Alcohols are preferred as the organic solvent, and from the viewpoint of recovering and reusing the organic solvent, it is preferable to use the same type of alcohol as the alcohol produced by the hydrolysis of the alkoxysilane. For example, when tetramethoxysilane is used as the alkoxysilane, methanol is preferred as the organic solvent.

[0020] Conventional known alkaline catalysts can be used. From the viewpoint of minimizing the inclusion of metal impurities, the alkaline catalyst is preferably at least one selected from the group consisting of ammonia, tetramethylammonium hydroxide, and other ammonium salts. Among these, ammonia is more preferred from the viewpoint of excellent catalytic activity. The alkaline catalyst may be used alone or in combination of two or more types.

[0021] In one embodiment, a method for synthesizing colloidal silica (a raw material solution containing colloidal silica particles) includes reacting tetramethoxysilane and water in a reaction solution containing tetramethoxysilane, water, and ammonia, in the presence of ammonia.

[0022] As methods for synthesizing colloidal silica (a raw material liquid containing colloidal silica particles) as described above, a two-liquid reaction type and a three-liquid reaction type are known. In the two-liquid reaction type, a liquid (addition side) containing alkoxysilane or a condensate thereof and an organic solvent is added to a liquid (receiving side) containing an alkali catalyst, water and an organic solvent. In the two-liquid reaction type, the liquid on the receiving side containing the alkali catalyst, water and the organic solvent contains all of water, which is one of the rate-determining factors of the reaction. On the other hand, in the three-liquid reaction type, a liquid (addition side) containing alkoxysilane or a condensate thereof and an organic solvent, and a liquid (addition side) containing water are added to a liquid (receiving side) containing an alkali catalyst, water and an organic solvent.

[0023] Hereinafter, the two-liquid reaction type synthesis method will be described.

[0024] The two-liquid reaction type synthesis method is not particularly limited, and a known method can be used. As the two-liquid reaction type synthesis method, a synthesis method comprising mixing a liquid (B) (also referred to as "liquid (B)" in the present specification) containing alkoxysilane or a condensate thereof and a second organic solvent with a liquid (A) (also referred to as "liquid (A)" in the present specification) containing an alkali catalyst, water and a first organic solvent to prepare a reaction liquid is preferred. In the reaction liquid, colloidal silica particles are generated by hydrolysis and polycondensation of the alkoxysilane or the condensate thereof.

[0025] The alkali catalyst, water, the organic solvent (the first organic solvent and the second organic solvent), and the alkoxysilane or the condensate thereof are as described above.

[0026] In one embodiment, the two-liquid reaction type synthesis method comprises mixing a liquid (B) containing tetramethoxysilane and methanol with a liquid (A) containing ammonia, water and methanol to prepare a reaction liquid.

[0027] Liquid (A) contains an alkali catalyst, water and a first organic solvent. Liquid (A) may contain other components in addition to the alkali catalyst, water and the first organic solvent. In a preferred embodiment, liquid (A) consists of the alkali catalyst, water and the first organic solvent.

[0028] (A) The lower limit of the alkaline catalyst content in the liquid is not particularly limited. The lower limit of the alkaline catalyst content in the liquid is preferably 0.1% by mass or more, more preferably 0.3% by mass or more, and even more preferably 0.5% by mass or more, based on the total mass of the liquid (A). The upper limit of the alkaline catalyst content in the liquid (A) is not particularly limited. From the viewpoint of productivity and cost, the upper limit of the alkaline catalyst content in the liquid (A) is preferably 50% by mass or less, more preferably 40% by mass or less, and even more preferably 20% by mass or less. The alkaline catalyst content in the liquid (A) is preferably 0.1% by mass or more and 50% by mass or less, more preferably 0.3% by mass or more and 40% by mass or less, and even more preferably 0.5% by mass or more and 20% by mass or less, based on the total mass of the liquid (A).

[0029] (A) The lower limit of the water content in the solution is not particularly limited and is adjusted according to the amount of alkoxysilane or its condensate used in the reaction. From the viewpoint of hydrolysis of alkoxysilane, the lower limit of the water content in the solution is preferably 1% by mass or more, more preferably 5% by mass or more, and even more preferably 9% by mass or more, relative to the total mass of the solution (A). The upper limit of the water content in the solution (A) is not particularly limited. From the viewpoint of compatibility with the solution (B), the upper limit of the water content in the solution (A) is preferably 50% by mass or less, more preferably 40% by mass or less, and even more preferably 30% by mass or less, relative to the total mass of the solution (A). The water content in the solution (A) is preferably 1% by mass or more and 50% by mass or less, more preferably 5% by mass or more and 40% by mass or less, and even more preferably 9% by mass or more and 30% by mass or less, relative to the total mass of the solution (A).

[0030] The lower limit of the content of the first organic solvent in (A) solution is not particularly limited. From the viewpoint of compatibility with (B) solution, the lower limit of the content of the first organic solvent in (A) solution is preferably 10% by mass or more, more preferably 20% by mass or more, and even more preferably 50% by mass or more, based on the total mass of (A) solution. The upper limit of the content of the first organic solvent is not particularly limited. From the viewpoint of dispersibility, the upper limit of the content of the first organic solvent is preferably 98% by mass or less, more preferably 95% by mass or less, and even more preferably 90% by mass or less, based on the total mass of (A) solution. The content of the first organic solvent is preferably 10% by mass or more and 98% by mass or less, more preferably 20% by mass or more and 95% by mass or less, and even more preferably 50% by mass or more and 90% by mass or less, based on the total mass of (A) solution.

[0031] (A) The method for producing the liquid is not particularly limited, and for example, a method of stirring and mixing an alkaline catalyst, water, a first organic solvent, and other components as needed can be used.

[0032] Solution (B) comprises an alkoxysilane or its condensate and a second organic solvent. Solution (B) may contain other components in addition to the alkoxysilane or its condensate and the second organic solvent. In a preferred embodiment, solution (B) consists of an alkoxysilane or its condensate and a second organic solvent.

[0033] (B) The lower limit of the content of alkoxysilane or its condensate in the solution is not particularly limited. The lower limit of the content of alkoxysilane or its condensate in the solution is preferably 50% by mass or more, more preferably 60% by mass or more, and even more preferably 70% by mass or more, based on the total amount (100% by mass) of the solution (B). The upper limit of the content of alkoxysilane or its condensate in the solution (B) is not particularly limited. The upper limit of the content of alkoxysilane or its condensate in the solution (B) is preferably 98% by mass or less, more preferably 95% by mass or less, and even more preferably 90% by mass or less, based on the total mass of the solution (B). (B) The content of alkoxysilane or its condensate in the liquid is preferably 50% by mass or more and 98% by mass or less, more preferably 60% by mass or more and 95% by mass or less, and even more preferably 70% by mass or more and 90% by mass or less.

[0034] (B) The lower limit of the content of the second organic solvent in the solution is not particularly limited. From the viewpoint of allowing the synthesis reaction of colloidal silica particles to proceed more gently and further suppressing the generation of gel-like substances, and from the viewpoint of miscibility, the lower limit of the content of the second organic solvent in the solution is preferably 2% by mass or more, more preferably 5% by mass or more, and even more preferably 10% by mass or more, relative to the total mass of the solution. (B) The upper limit of the content of the second organic solvent in the solution is not particularly limited. From the viewpoint of increasing the silica particle concentration in the reaction solution and further improving productivity, the upper limit of the content of the second organic solvent in the solution is preferably 50% by mass or less, more preferably 40% by mass or less, and even more preferably 30% by mass or less. (B) The content of the second organic solvent in the solution is preferably 2% by mass or more and 50% by mass or less, more preferably 5% by mass or more and 40% by mass or less, and even more preferably 10% by mass or more and 30% by mass or less.

[0035] The method for producing liquid (B) is not particularly limited. From the viewpoint of miscibility, it is preferable to use a method in which alkoxysilane and other components as needed are stirred and mixed in a second organic solvent.

[0036] When mixing solution (A) with solution (B), the method of adding solution (B) is not particularly limited, and methods such as continuous addition or partial addition (for example, dropwise addition) can be used.

[0037] When adding and mixing solution (B) to solution (A), the rate at which solution (B) is added is not particularly limited and can be adjusted as appropriate within a range that does not generate a gel-like substance.

[0038] The temperatures of solution (A), solution (B), and the reaction solution are not particularly limited, but are, for example, between 5°C and 100°C, and preferably between 5°C and 70°C. It is preferable that the temperatures of solution (A), solution (B), and the reaction solution are the same.

[0039] The hydrolysis and polycondensation reactions in the reaction solution can be carried out under any pressure conditions: reduced pressure, atmospheric pressure, or pressurized pressure. However, from the viewpoint of production costs, it is preferable to carry them out under atmospheric pressure.

[0040] The synthesized colloidal silica (raw material liquid containing colloidal silica particles) can be used as is for preparing the liquid according to this embodiment, or for preparing surface-modified colloidal silica particles as described later. The synthesized colloidal silica (raw material liquid containing colloidal silica particles) may be subjected to treatments such as water displacement and concentration. Conventional known methods can be used for water displacement and concentration.

[0041] The colloidal silica particles may be unmodified colloidal silica particles or surface-modified colloidal silica particles.

[0042] In one embodiment, the colloidal silica particles may include surface-modified colloidal silica particles. The surface-modified colloidal silica particles may be anionically modified colloidal silica particles or cationically modified colloidal silica particles. Examples of anionically modified colloidal silica particles include colloidal silica on which anionic groups such as sulfonic acid groups, carboxylic acid groups, phosphonic acid groups, and aluminic acid groups are immobilized on the surface. Examples of cationically modified colloidal silica particles include colloidal silica on which cationic groups such as amino groups are immobilized on the surface.

[0043] In a preferred embodiment, the colloidal silica particles include anion-modified colloidal silica particles, more preferably sulfonic acid-modified colloidal silica particles, and even more preferably sulfonic acid-modified colloidal silica particles.

[0044] The method for producing anionically modified colloidal silica particles is not particularly limited, and one example is a method of reacting colloidal silica particles with a silane coupling agent having anionic groups at its terminals.

[0045] As a specific example, if you want to immobilize sulfonic acid groups onto colloidal silica particles, you can do so by the method described in “Sulfonic acid-functionalized silica through quantitative oxidation of thiol groups”, Chem. Commun. 246-247 (2003). Specifically, by coupling a silane coupling agent having a thiol group, such as 3-mercaptopropyltrimethoxysilane, to colloidal silica particles and then oxidizing the thiol group with hydrogen peroxide, you can obtain a liquid containing colloidal silica particles on which sulfonic acid groups are immobilized on the surface (sulfonic acid-modified colloidal silica particles).

[0046] If the carboxyl group is to be immobilized on colloidal silica particles, this can be done, for example, by the method described in “Novel Silane Coupling Agents Containing a Photolabile 2-Nitrobenzyl Ester for Introduction of a Carboxy Group on the Surface of Silica Gel”, Chemistry Letters, 3,228-229 (2000). Specifically, by coupling a silane coupling agent containing a photoreactive 2-nitrobenzyl ester to colloidal silica particles and then irradiating them with light, a liquid containing colloidal silica particles with carboxyl groups immobilized on the surface (carboxylic acid-modified colloidal silica particles) can be obtained.

[0047] The method for producing cation-modified colloidal silica particles is not particularly limited, and one example is a method of immobilizing a silane coupling agent having an amino group, such as aminoethyltrimethoxysilane, aminopropyltrimethoxysilane, aminoethyltriethoxysilane, aminopropyltriethoxysilane, aminopropyldimethylethoxysilane, aminopropylmethyldiethoxysilane, or aminobutyltriethoxysilane, on the surface of silica particles, as described in Japanese Patent Application Publication No. 2005-162533. This makes it possible to obtain colloidal silica particles with amino groups immobilized on the surface (amino group-modified colloidal silica particles).

[0048] The average secondary particle diameter of colloidal silica particles is not particularly limited. The lower limit of the average secondary particle diameter of colloidal silica particles is preferably 10 nm or more, more preferably 20 nm or more, and even more preferably 30 nm or more. The upper limit of the average secondary particle diameter of colloidal silica particles is preferably 700 nm or less, more preferably 350 nm or less, and even more preferably 220 nm or less. The average secondary particle diameter of colloidal silica particles is preferably 10 nm or more and 700 nm or less, more preferably 20 nm or more and 350 nm or less, and even more preferably 30 nm or more and 220 nm or less.

[0049] The average secondary particle diameter of colloidal silica particles can be measured by dynamic light scattering methods, such as laser diffraction scattering. Specifically, the average secondary particle diameter of colloidal silica particles corresponds to the particle diameter D50 in the particle size distribution of abrasive grains determined by laser diffraction scattering, where the cumulative particle mass from the finest particles reaches 50% of the total particle mass.

[0050] The size of colloidal silica particles (average secondary particle diameter, etc.) can be appropriately controlled by selecting the synthesis method for colloidal silica (raw material liquid containing colloidal silica particles).

[0051] The shape of colloidal silica particles is not particularly limited and may be spherical or non-spherical. Specific examples of non-spherical shapes include polygonal prisms such as triangular or square prisms, cylindrical shapes, cylindrical shapes with a bulge in the center, donut shapes with a hole in the center, plate shapes, so-called cocoon shapes with a constriction in the center, so-called aggregate spherical shapes where multiple particles are integrated, so-called konpeito shapes with multiple protrusions on the surface, rugby ball shapes, and many other shapes, and are not particularly limited.

[0052] The content (concentration) of colloidal silica particles is not particularly limited as long as it is suitable for ion exchange. The content of colloidal silica particles is, for example, 1% by mass or more and 40% by mass or less, preferably 5% by mass or more and 30% by mass or less, and more preferably 15% by mass or more and 25% by mass or less, based on the total mass of the liquid containing colloidal silica particles and hydrogen peroxide.

[0053] In the liquid according to this embodiment, the zeta potential of the colloidal silica particles is not particularly limited. The upper limit of the zeta potential of the colloidal silica particles is, for example, -20mV or less. The lower limit of the zeta potential of the colloidal silica particles may be, for example, -65mV or more or -50mV or more.

[0054] The liquid according to this embodiment contains hydrogen peroxide.

[0055] The hydrogen peroxide content (concentration) is not particularly limited. The lower limit of the hydrogen peroxide content is, for example, 50 ppm (0.005%) or more, preferably 80 ppm (0.008%) or more, and more preferably 100 ppm (0.01%) or more, relative to the total mass of the liquid containing colloidal silica particles and hydrogen peroxide. The lower limit of the hydrogen peroxide content may be 200 ppm (0.02%) or more, or 350 ppm (0.035%) or more, relative to the total mass of the liquid containing colloidal silica particles and hydrogen peroxide. The upper limit of the hydrogen peroxide content is, for example, 10,000 ppm (1%) or less, preferably 7,000 ppm (0.7%) or less, and more preferably 5,000 ppm (0.5%) or less, relative to the total mass of the liquid containing colloidal silica particles and hydrogen peroxide. The upper limit of the hydrogen peroxide content may be 1000 ppm (0.1% by mass), 500 ppm (0.05% by mass), or 400 ppm (0.04% by mass) or less, relative to the total mass of the liquid containing colloidal silica particles and hydrogen peroxide. The hydrogen peroxide content is, for example, 50 ppm (0.005% by mass) or more and 10000 ppm (1% by mass) or less, preferably 80 ppm (0.008% by mass) or more and 7000 ppm (0.7% by mass) or less, and more preferably 100 ppm (0.01% by mass) or more and 5000 ppm (0.5% by mass) or less, relative to the total mass of the liquid containing colloidal silica particles and hydrogen peroxide. The hydrogen peroxide content (concentration) may be a value calculated from the amount of hydrogen peroxide used, or a value measured by the method described in the examples may be used.

[0056] The liquid containing colloidal silica particles and hydrogen peroxide contains by-products resulting from the reaction between hydrogen peroxide and residues of components used in the manufacturing process of colloidal silica particles, the manufacturing process of surface-modified colloidal silica particles, and other similar processes.

[0057] In this specification, "residues of components used in the manufacturing process of colloidal silica particles, the manufacturing process of surface-modified colloidal silica particles, etc." is also simply referred to as "residues relating to this embodiment."

[0058] In this specification, the by-products resulting from the reaction between hydrogen peroxide and the residue according to this embodiment are also simply referred to as "by-products."

[0059] Residues in this embodiment include organic solvents. Organic solvents are used in the synthesis of colloidal silica particles and the production of surface-modified colloidal silica particles. Examples of organic solvents include alcohols such as methanol, ethanol, n-propanol, isopropanol, ethylene glycol, propylene glycol, and 1,4-butanediol; and ketones such as acetone and methyl ethyl ketone.

[0060] In one embodiment, the residue according to this embodiment is methanol, and the by-product of the reaction between hydrogen peroxide and methanol is formaldehyde. The generation of formaldehyde can be confirmed by measuring the formaldehyde content (concentration).

[0061] In the liquid according to this embodiment, the lower limit of the formaldehyde content (concentration) may be 1.0 ppm (0.0001% by mass) or more, 3.0 ppm (0.0003% by mass) or more, 4.0 ppm (0.0004% by mass) or more, 5.0 ppm (0.0005% by mass) or more, or 6.0 ppm (0.0006% by mass) or more, relative to the total mass of the liquid containing colloidal silica particles and hydrogen peroxide. The upper limit of the formaldehyde content (concentration) may be 30.0 ppm (0.003% by mass) or less, 25.0 ppm (0.0025% by mass) or less, 15.0 ppm (0.0015% by mass) or less, 10.0 ppm (0.001% by mass) or less, or 8.0 ppm (0.0008% by mass) or less, relative to the total mass of the liquid containing colloidal silica particles and hydrogen peroxide. The formaldehyde content may be between 1.0 ppm (0.0001%) and 30.0 ppm (0.003%), 3.0 ppm (0.0003%) and 25.0 ppm (0.0025%), 4.0 ppm (0.0004%) and 15.0 ppm (0.0015%), 5.0 ppm (0.0005%) and 10.0 ppm (0.001%), or 6.0 ppm (0.0006%) and 8.0 ppm (0.0008%), relative to the total mass of the liquid containing colloidal silica particles and hydrogen peroxide. The formaldehyde content (concentration) shall be the value measured by the method described in the examples.

[0062] The liquid according to this embodiment includes a dispersion medium for dispersing each component. Examples of dispersion mediums include water; alcohols such as methanol, ethanol, and ethylene glycol; ketones such as acetone, and mixtures thereof. From the viewpoint of suppressing by-products, the dispersion medium preferably contains water, more preferably consists substantially of water, and even more preferably is water. The above "substantially" means that a dispersion medium other than water may be included insofar as the objective effects of the present invention can be achieved. More specifically, it preferably consists of 90% to 100% by mass of water and 0% to 10% by mass of a dispersion medium other than water, and more preferably consists of 99% to 100% by mass of water and 0% to 1% by mass of a dispersion medium other than water. As for the water, water that contains as few impurities as possible is preferred. Specifically, the water is more preferably water from which impurity ions have been removed using an ion exchange resin and then filtered to remove foreign matter (pure water or ultrapure water), or distilled water.

[0063] The method for preparing the solution containing colloidal silica particles and hydrogen peroxide is not particularly limited. The solution containing colloidal silica particles and hydrogen peroxide can be prepared, for example, by mixing a raw material solution containing colloidal silica particles with hydrogen peroxide solution so that the colloidal silica particles and hydrogen peroxide are at the desired concentrations. If the colloidal silica particles include sulfonic acid-modified colloidal silica particles, and hydrogen peroxide is used in the manufacturing process of the sulfonic acid-modified colloidal silica particles, then the solution containing the sulfonic acid-modified colloidal silica particles can be used as the solution containing colloidal silica particles and hydrogen peroxide.

[0064] In the ion exchange step, the liquid containing colloidal silica particles and hydrogen peroxide is brought into contact with an ion exchange resin. This allows for the removal of at least some of the by-products in the liquid containing colloidal silica particles and hydrogen peroxide. In a preferred embodiment, the ion exchange step includes the removal of at least some of the formaldehyde in the liquid containing colloidal silica particles and hydrogen peroxide.

[0065] Removing at least a portion of the by-products in the liquid containing colloidal silica particles and hydrogen peroxide means that the by-product content in the dispersion containing colloidal silica particles after the ion exchange step is lower than the by-product content in the liquid containing colloidal silica particles and hydrogen peroxide.

[0066] Specifically, removing at least a portion of the by-products in the liquid containing colloidal silica particles and hydrogen peroxide means that the reduction rate of the by-product content is 15% or more. The reduction rate of the by-product content can be calculated using the following formula: Reduction rate of by-product content (%) = ((AB) / A) × 100 A: Content (mass ppm) of by-products in the liquid containing colloidal silica particles and hydrogen peroxide. B: By-product content (mass ppm) in the dispersion containing colloidal silica particles.

[0067] When the by-product is formaldehyde, the reduction rate of the formaldehyde content is 15% or more, preferably 30% or more, more preferably 60% or more, even more preferably 75% or more, even more preferably 85% or more, and particularly preferably 95% or more (upper limit: 100%).

[0068] The ion exchange resin is not particularly limited, but examples include cation exchange resins such as strongly acidic cation exchange resins and weakly acidic cation exchange resins; and anion exchange resins such as strongly basic anion exchange resins (strongly basic type I anion exchange resins and strongly basic type II anion exchange resins) and weakly basic anion exchange resins.

[0069] Examples of exchange groups found in strongly acidic cation exchange resins include sulfonic acid groups. Examples of exchange groups found in weakly acidic cation exchange resins include carboxyl groups and phenolic hydroxyl groups.

[0070] Examples of exchange groups found in strongly basic type I anion exchange resins include trimethylammonium groups. Examples of exchange groups found in strongly basic type II anion exchange resins include dimethylethanolammonium groups. Examples of exchange groups found in weakly basic anion exchange resins include polyamines and tertiary amines.

[0071] When the by-product is formaldehyde, the ion exchange resin is preferably an anion exchange resin, more preferably a strongly basic type I anion exchange resin or a weakly basic anion exchange resin, and even more preferably a strongly basic type I anion exchange resin, from the viewpoint of being able to remove formaldehyde more effectively.

[0072] Commercially available ion exchange resins may be used. Examples of commercially available products include the Duolite® series (manufactured by DuPont), the Diaion® series (manufactured by Mitsubishi Chemical Corporation), SGC650 (manufactured by Purolite Co., Ltd.), Amberlite®, and Amberjet® (manufactured by Organo Corporation).

[0073] The method for contacting the colloidal silica particles and hydrogen peroxide-containing solution with the ion exchange resin is not particularly limited, and conventionally known methods can be used. Examples include mixing the colloidal silica particles and hydrogen peroxide-containing solution with the ion exchange resin, or passing the colloidal silica particles and hydrogen peroxide-containing solution through a column packed with the ion exchange resin.

[0074] When mixing a liquid containing colloidal silica particles and hydrogen peroxide with an ion exchange resin, the amount of ion exchange resin used can be appropriately adjusted according to the content of colloidal silica particles in the liquid containing colloidal silica particles and hydrogen peroxide. The lower limit of the amount of ion exchange resin used is, for example, 1 part by mass or more, preferably 3 parts by mass or more, and more preferably 5 parts by mass or more, per 1000 parts by mass of colloidal silica particles. The upper limit of the amount of ion exchange resin used is, for example, 80 parts by mass or less, preferably 60 parts by mass or less, and more preferably 45 parts by mass or less, per 1000 parts by mass of colloidal silica particles. The amount of ion exchange resin used is, for example, 1 part by mass or more and 80 parts by mass or less, preferably 3 parts by mass or more and 60 parts by mass or less, and more preferably 5 parts by mass or more and 45 parts by mass or less.

[0075] When using a strongly basic anion exchange resin as the ion exchange resin, the amount of ion exchange resin used is preferably 5 to 80 parts by mass, more preferably 10 to 60 parts by mass, and even more preferably 15 to 45 parts by mass, per 1000 parts by mass of colloidal silica particles.

[0076] When using a weakly basic anion exchange resin as the ion exchange resin, the amount of ion exchange resin used is preferably 15 parts by mass or more and 80 parts by mass or less, and more preferably 45 parts by mass or more and 60 parts by mass or less, per 1000 parts by mass of colloidal silica particles.

[0077] When mixing (stirring) a liquid containing colloidal silica particles and hydrogen peroxide with an ion exchange resin, the mixing (stirring) temperature is, for example, 10°C to 50°C, preferably 20°C to 30°C. The mixing (stirring) time is not particularly limited, for example, 10 minutes to 60 minutes, preferably 20 minutes to 40 minutes. The stirring speed during mixing (stirring) is not particularly limited and can be set as appropriate (for example, 600 rpm).

[0078] After ion exchange is complete, a dispersion containing colloidal silica particles can be obtained by separating and removing the ion exchange resin. The method for separating and removing the ion exchange resin is not particularly limited. For example, a dispersion containing colloidal silica particles can be obtained by filtration using filter paper, settling the ion exchange resin by centrifugation or natural settling, and collecting the supernatant. The content of colloidal silica particles and dispersion medium in the dispersion containing colloidal silica particles is the same as the content of colloidal silica particles and dispersion medium in the liquid according to the above embodiment. The content of hydrogen peroxide in the dispersion containing colloidal silica particles is reduced from the content of hydrogen peroxide in the liquid according to the above embodiment, and the rate of reduction varies depending on the type of ion exchange resin used, for example, about 1% by mass or more and about 100% by mass or less, preferably 3% by mass or more and 98% by mass or less, and more preferably 50% by mass or more and 96% by mass or less.

[0079] In a dispersion containing colloidal silica particles, at least a portion of the by-products in the solution containing the colloidal silica particles and hydrogen peroxide are removed. In the ion exchange step, the by-products in the dispersion containing colloidal silica particles are removed until they are below a desired content, depending on the type of by-product. If the by-product is formaldehyde, the formaldehyde in the dispersion containing colloidal silica particles is removed until it is, for example, 6.0 ppm (0.0006%) or less, preferably 3.0 ppm (0.0003%) or less, more preferably 2.0 ppm (0.0002%) or less, and particularly preferably 1.0 ppm (0.0001%) or less, relative to the total mass of the dispersion containing colloidal silica particles (lower limit: 0 ppm (0%)).

[0080] [Preparation process] The method for producing a dispersion containing colloidal silica particles according to this embodiment may include a preparation step of preparing a solution containing colloidal silica particles and hydrogen peroxide before the ion exchange step described above.

[0081] In the preparation step, a solution containing colloidal silica particles and hydrogen peroxide is prepared. The composition of the solution containing colloidal silica particles and hydrogen peroxide, the method for synthesizing the colloidal silica particles, and the method for preparing the solution containing colloidal silica particles and hydrogen peroxide are as described above.

[0082] In one embodiment, the preparation step includes synthesizing colloidal silica particles and mixing the synthesized colloidal silica particles with hydrogen peroxide, preferably by an alkoxide method, and mixing the synthesized colloidal silica particles with hydrogen peroxide. Details of the alkoxide method are as described above.

[0083] In one embodiment, the preparation step includes synthesizing colloidal silica particles, modifying the surface of the synthesized colloidal silica particles, and mixing the surface-modified colloidal silica particles with hydrogen peroxide, preferably by an alkoxide method, modifying the surface of the synthesized colloidal silica particles, and mixing the surface-modified colloidal silica particles with hydrogen peroxide.

[0084] In one embodiment, the preparation step includes synthesizing colloidal silica particles and modifying the surface of the synthesized colloidal silica particles with sulfonic acid groups, preferably by an alkoxide method, and modifying the surface of the synthesized colloidal silica particles with sulfonic acid groups.

[0085] The preparation step may further include confirming the presence of by-products in the liquid containing colloidal silica particles and hydrogen peroxide. The method for confirming the presence of by-products can be appropriately selected from conventionally known methods depending on the type of by-product. If the by-product is formaldehyde, the preparation step may further include confirming the presence of aldehyde in the liquid containing colloidal silica particles and hydrogen peroxide. The presence of formaldehyde can be confirmed by measuring its formaldehyde content (concentration). The formaldehyde content (concentration) can be measured by the method described in the examples.

[0086] [Application] A dispersion containing colloidal silica particles produced by the manufacturing method according to this embodiment can be used in a variety of applications. In particular, it can be suitably used as an abrasive for polishing objects such as semiconductor substrates.

[0087] <Polishing composition> One aspect of the present invention is an abrasive composition comprising a dispersion containing colloidal silica particles produced by the above-described manufacturing method. The colloidal silica particles contained in the dispersion produced by the above-described manufacturing method can be used as an abrasive (abrasive grain) contained in the abrasive composition.

[0088] The polishing composition according to this embodiment may consist of a dispersion containing colloidal silica particles produced by the above-described manufacturing method, or it may contain, in addition to the dispersion containing colloidal silica particles produced by the above-described manufacturing method, other known components such as a dispersion medium, pH adjuster, chelating agent, thickener, oxidizing agent, dispersant, surface protectant, wetting agent, surfactant, rust inhibitor, preservative, and fungicide. The content of the other components may be appropriately set according to their purpose of addition.

[0089] The object to be polished with the polishing composition according to this embodiment is not particularly limited and includes, for example, single-crystal silicon, polycrystalline silicon (polysilicon), polycrystalline silicon doped with n-type or p-type impurities, amorphous silicon, amorphous silicon doped with n-type or p-type impurities, silicon oxide, silicon nitride, silicon carbonitride (SiCN), metals, SiGe, carbon-containing materials, low-dielectric materials (low-k materials), etc.

[0090] A polishing method using the polishing composition according to this embodiment includes a polishing method in which the object to be polished is polished with the polishing composition according to this embodiment.

[0091] As a polishing device, a general polishing device can be used that has a holder for holding a substrate or the like with the object to be polished, a motor with adjustable rotation speed, and a polishing platen to which a polishing pad (abrasive cloth) can be attached.

[0092] As the polishing pad, general nonwoven fabrics, polyurethanes, and porous fluororesins can be used without any particular restrictions. Preferably, the polishing pad has grooves that allow the polishing liquid to accumulate.

[0093] Regarding the polishing conditions, for example, the rotational speed of the polishing platen and carrier (head) should be 10 rpm (0.17 s). -1 ) or more 500rpm (8.33s -1 Preferably, the pressure applied to the substrate containing the object to be polished (polishing pressure) is between 0.5 psi (3.45 kPa) and 10 psi (68.9 kPa).

[0094] The method of supplying the polishing composition to the polishing pad is not particularly limited, and for example, a method of continuous supply using a pump or the like can be employed. There is no limit to the amount supplied, but it is preferable that the surface of the polishing pad is always covered with the polishing composition according to this embodiment.

[0095] The polishing composition according to this embodiment may be a one-component type or a multi-component type, including a two-component type. The polishing composition according to this embodiment may be prepared by diluting the stock solution of the polishing composition with a diluent such as water, for example, three times or more.

[0096] <Method for producing abrasive compositions> One aspect of the present invention is a method for producing an abrasive composition comprising a dispersion containing colloidal silica particles, the method comprising producing a dispersion containing colloidal silica particles by the above-described method for producing a dispersion.

[0097] The method for producing the polishing composition according to this embodiment is not particularly limited. When the dispersion produced by the above-described method is used as the polishing composition, the method for producing the polishing composition according to this embodiment is the same as the method for producing the dispersion containing colloidal silica particles described above.

[0098] If the polishing composition contains other components in addition to the dispersion produced by the above-described manufacturing method, the method for producing the polishing composition according to this embodiment includes stirring and mixing the dispersion produced by the above-described manufacturing method with the other components. The temperature during stirring and mixing is not particularly limited, for example, 10°C or more and 40°C or less. The temperature during stirring and mixing may be heated to increase the dissolution rate. The time for stirring and mixing is not particularly limited.

[0099] The present invention encompasses the following aspects and embodiments. [1] A method for producing a dispersion containing colloidal silica particles, comprising an ion exchange step of contacting a liquid containing colloidal silica particles and hydrogen peroxide with an ion exchange resin. [2] A method for producing the dispersion according to [1], comprising a preparation step of preparing a liquid containing the colloidal silica particles and hydrogen peroxide before the ion exchange step. [3] The method for producing the dispersion according to [1] or [2] above, wherein the colloidal silica particles are silica particles produced by the alkoxide method. [4] The method for producing a dispersion according to any one of [1] to [3] above, wherein the ion exchange resin is an anion exchange resin. [5] The method for producing the dispersion according to any one of [1] to [4] above, wherein the colloidal silica particles include anion-modified colloidal silica particles. [6] The method for producing the dispersion according to any one of [1] to [5] above, wherein the colloidal silica particles include sulfonic acid-modified colloidal silica particles. [7] The method for producing the dispersion according to [4] above, wherein the anion exchange resin is a strongly basic anion exchange resin. [8] A method for producing a dispersion according to any one of [1] to [7] above, wherein the ion exchange step includes removing at least a portion of the formaldehyde in the liquid containing the colloidal silica particles and hydrogen peroxide. [9] An abrasive composition comprising a dispersion prepared by any of the manufacturing methods described in [1] to [8] above.

[10] A method for producing an abrasive composition comprising a dispersion containing colloidal silica particles, comprising producing the dispersion containing colloidal silica particles by the method for producing a dispersion described in any of [1] to [8] above. [Examples]

[0100] The present invention will be described in more detail using the following examples and comparative examples. However, the technical scope of the present invention is not limited to the following examples. Unless otherwise specified, "%" and "parts" mean "mass%" and "parts by mass," respectively. In addition, in the following examples, unless otherwise specified, the operations were carried out under conditions of room temperature (20°C to 25°C) and relative humidity of 40%RH to 50%RH.

[0101] <Preparation of Solution 1 containing colloidal silica particles and hydrogen peroxide> A mixture of 2180.8 g of pure water, 508.6 g of 29% by mass aqueous ammonia (alkaline catalyst), and 12391 g of methanol was prepared. To this mixture, 1522.2 g of tetramethoxysilane and 413.0 g of methanol were added dropwise over 25 minutes while maintaining the liquid temperature at 20°C to obtain a raw material solution containing colloidal silica particles dispersed in water and methanol.

[0102] To the raw material solution containing the colloidal silica particles obtained above, 30% by mass hydrogen peroxide solution was added to achieve a final hydrogen peroxide concentration of 100 ppm by mass to prepare solution 1 containing colloidal silica particles and hydrogen peroxide (colloidal silica particle content: 19.6% by mass). The formaldehyde content in solution 1 containing colloidal silica particles and hydrogen peroxide was measured to confirm that formaldehyde was generated.

[0103] <Preparation of Solution 2 containing colloidal silica particles and hydrogen peroxide> Solution 2, containing colloidal silica particles and hydrogen peroxide, was prepared in the same manner as Solution 1, except that the final concentration of hydrogen peroxide was changed to 1000 ppm by mass (colloidal silica particle content: 19.5% by mass). The formaldehyde content in Solution 2, containing colloidal silica particles and hydrogen peroxide, was measured to confirm that formaldehyde was generated.

[0104] <Preparation of Solution 3 containing colloidal silica particles and hydrogen peroxide> Solution 3, containing colloidal silica particles and hydrogen peroxide, was prepared in the same manner as Solution 1, except that the final concentration of hydrogen peroxide was changed to 5000 ppm by mass (colloidal silica particle content: 19.3% by mass). The formaldehyde content in Solution 3, containing colloidal silica particles and hydrogen peroxide, was measured to confirm that formaldehyde was generated.

[0105] <Preparation of Solution 4 containing colloidal silica particles and hydrogen peroxide> A mixture of 869.3 g of pure water, 704.6 g of 29% by mass aqueous ammonia (alkaline catalyst), and 12924 g of methanol was prepared. To this mixture, 1522.2 g of tetramethoxysilane and 413.0 g of methanol were added dropwise over 55 minutes while maintaining the liquid temperature at 35°C to obtain a raw material solution containing colloidal silica particles dispersed in water and methanol.

[0106] The starting liquid containing the colloidal silica particles obtained above was heated and concentrated to 5000 mL under atmospheric pressure. 6.0 g of 3-mercaptopropyltrimethoxysilane was added to this concentrate as a silane coupling agent, and the mixture was heated and matured under reflux at the boiling point. Then, methanol and ammonia were replaced with water while adding pure water to maintain a constant volume, and the temperature of the concentrate was lowered to room temperature when the pH fell below 8. Next, 62.4 g of 30% by mass hydrogen peroxide solution was added, and the mixture was heated again. The reaction continued for 8 hours, and after cooling to room temperature, a reaction solution containing sulfonic acid-modified colloidal silica particles was obtained.

[0107] Next, to allow it to cool, the reaction solution obtained above was left to stand overnight, and 0.0343 g of 30% by mass hydrogen peroxide solution (3 moles per mole of silane coupling agent) was added, and it was brought to a boil again. After that, the solution was replaced with pure water for 2 hours, and then cooled to room temperature (25°C) to prepare solution 4 containing colloidal silica particles (sulfonic acid-modified colloidal silica particles) and hydrogen peroxide (colloidal silica particle content: 20.0% by mass). The formaldehyde content in solution 4 containing colloidal silica particles and hydrogen peroxide was measured to confirm that formaldehyde was generated.

[0108] <Preparation of solution 5 containing colloidal silica particles and hydrogen peroxide> A mixture of 2271.4 g of pure water, 508.6 g of 26% by mass aqueous ammonia (alkaline catalyst), and 12391 g of methanol was prepared. To this mixture, 1522.2 g of tetramethoxysilane and 413.0 g of methanol were added dropwise over 25 minutes while maintaining the liquid temperature at 20°C to obtain a raw material solution containing colloidal silica particles dispersed in water and methanol.

[0109] The raw material solution containing the colloidal silica particles obtained above was heated and concentrated to 2500 mL under atmospheric pressure. 6.0 g of 3-mercaptopropyltrimethoxysilane was added to this concentrate as a silane coupling agent, and the mixture was heated and matured under reflux at the boiling point. Then, methanol and ammonia were replaced with water while adding pure water to maintain a constant volume, and the temperature of the concentrate was lowered to room temperature when the pH fell below 8. Next, 32.6 g of 30% by mass hydrogen peroxide solution was added, and the mixture was heated again. The reaction continued for 8 hours, and after cooling to room temperature, a reaction solution containing sulfonic acid-modified colloidal silica particles was obtained.

[0110] Next, to allow it to cool, the reaction solution obtained above was left to stand overnight, and 0.0343 g of 30% by mass hydrogen peroxide solution (3 moles per mole of silane coupling agent) was added, and it was brought to a boil again. After that, the solution was replaced with pure water for 2 hours, and then cooled to room temperature (25°C) to prepare solution 5 containing colloidal silica particles (sulfonic acid-modified colloidal silica particles) and hydrogen peroxide (colloidal silica particle content: 20.0% by mass). The formaldehyde content in solution 5 containing colloidal silica particles and hydrogen peroxide was measured to confirm that formaldehyde was generated.

[0111] <Methods for measuring various physical properties> In solutions 1-5 containing colloidal silica particles and hydrogen peroxide, various physical properties were measured using the following methods.

[0112] (Average secondary particle size) The average secondary particle size of colloidal silica particles was measured using a light scattering method with laser light. The measurement instrument used was the UPA-UT151 dynamic light scattering particle size distribution analyzer manufactured by Nikkiso Co., Ltd.

[0113] (Zeta potential) A solution containing colloidal silica particles and hydrogen peroxide was subjected to a Zetasizer Nano manufactured by Malvern Panalytical, and measurements were performed using a flow cell at a measurement temperature of 25°C by laser Doppler (electrophoretic light scattering measurement). The obtained data was analyzed using Smoluchowski's equation to calculate the zeta potential of the colloidal silica particles and the colloidal silica particles contained in the solution containing hydrogen peroxide.

[0114] (Hydrogen peroxide content) The hydrogen peroxide content in solutions 1-3, which contain colloidal silica particles and hydrogen peroxide, was calculated from the amount of 30% hydrogen peroxide solution used.

[0115] For solutions 4 and 5 containing colloidal silica particles and hydrogen peroxide, the hydrogen peroxide content was measured using a potentiometric automatic titrator COM-1700 manufactured by Hiranuma Sangyo Co., Ltd. Specifically, 50 g of a solution (solution 4 or solution 5) containing colloidal silica particles and hydrogen peroxide was mixed with 100 g of water to obtain solution A. Then, 10 g of 10% by mass aqueous sulfuric acid solution was added to solution A to obtain the evaluation solution. An aqueous potassium permanganate solution with a factor of 1.0 (0.02 mol / L) was used as the titrator, and the evaluation solution was titrated. The hydrogen peroxide content was determined from the titration volume of the potassium permanganate solution.

[0116] (Formaldehyde content) The solution containing colloidal silica particles and hydrogen peroxide was centrifuged (25°C, 365710G, 10 minutes), and the supernatant was collected. To 10 mL of the 10-fold diluted supernatant, 0.2 mL of a 5-fold diluted solution of 85% phosphoric acid in water was added, followed by 0.5 mL of a 1 mg / mL solution of 2,4-dinitrophenylhydrazine acetonitrile, and the mixture was mixed. The mixture was then allowed to stand for 20 minutes to obtain the test solution.

[0117] The formaldehyde content was determined by measuring the test solution using high-performance liquid chromatography (HPLC) under the following conditions: HPLC measurement conditions Column: InertSustain C18 (reverse-phase column) Eluent: Acetonitrile / H2O = 50 / 50 Flow rate: 1mL / min Detection: UV360nm.

[0118] Table 1 shows the average secondary particle size, content, surface modification groups, and zeta potential of the colloidal silica particles in solutions 1 to 5 containing colloidal silica particles and hydrogen peroxide, as well as the hydrogen peroxide and formaldehyde content in the solutions containing colloidal silica particles and hydrogen peroxide.

[0119] [Table 1]

[0120] <Example 1> To a solution containing colloidal silica particles and hydrogen peroxide, 45 g of strongly basic type I anion exchange resin (Duolite® HPR550(OH), manufactured by DuPont) was added per 1000 g of colloidal silica particles, and ion exchange was performed by stirring at 25°C and 600 rpm for 30 minutes. After ion exchange, the solution was filtered using filter paper, and the supernatant was collected to obtain a dispersion containing colloidal silica particles.

[0121] <Example 2> A dispersion containing colloidal silica particles was obtained in the same manner as in Example 1, except that solution 2 containing colloidal silica particles and hydrogen peroxide was used instead of solution 1 containing colloidal silica particles and hydrogen peroxide.

[0122] <Example 3> A dispersion containing colloidal silica particles was obtained in the same manner as in Example 1, except that solution 3 containing colloidal silica particles and hydrogen peroxide was used instead of solution 1 containing colloidal silica particles and hydrogen peroxide.

[0123] <Example 4> A dispersion containing colloidal silica particles was obtained in the same manner as in Example 1, except that solution 4 containing colloidal silica particles and hydrogen peroxide was used instead of solution 1 containing colloidal silica particles and hydrogen peroxide, and 5 g of strongly basic type I anion exchange resin (Duolite® HPR550(OH), manufactured by DuPont) was added per 1000 g of colloidal silica particles.

[0124] <Example 5> A dispersion containing colloidal silica particles was obtained in the same manner as in Example 4, except that 10 g of strongly basic type I anion exchange resin (Duolite® HPR550(OH), manufactured by DuPont) was added per 1000 g of colloidal silica particles.

[0125] <Example 6> A dispersion containing colloidal silica particles was obtained in the same manner as in Example 4, except that 15 g of strongly basic type I anion exchange resin (Duolite® HPR550(OH), manufactured by DuPont) was added per 1000 g of colloidal silica particles.

[0126] <Example 7> A dispersion containing colloidal silica particles was obtained in the same manner as in Example 4, except that 45 g of strongly basic type I anion exchange resin (Duolite® HPR550(OH), manufactured by DuPont) was added per 1000 g of colloidal silica particles.

[0127] <Example 8> A dispersion containing colloidal silica particles was obtained in the same manner as in Example 6, except that a weakly basic anion exchange resin (Diaion® WA20, manufactured by Mitsubishi Chemical Corporation) was used instead of a strongly basic type I anion exchange resin (Duolite® HPR550(OH), manufactured by DuPont).

[0128] <Example 9> A dispersion containing colloidal silica particles was obtained in the same manner as in Example 8, except that 45 g of a weakly basic anion exchange resin (Diaion® WA20, manufactured by Mitsubishi Chemical Corporation) was added per 1000 g of colloidal silica particles.

[0129] <Example 10> A dispersion containing colloidal silica particles was obtained in the same manner as in Example 6, except that a weakly basic anion exchange resin (Diaion® WA30, manufactured by Mitsubishi Chemical Corporation) was added instead of a strongly basic type I anion exchange resin (Duolite® HPR550(OH), manufactured by DuPont).

[0130] <Example 11> A dispersion containing colloidal silica particles was obtained in the same manner as in Example 10, except that 45 g of a weakly basic anion exchange resin (Diaion® WA30, manufactured by Mitsubishi Chemical Corporation) was added per 1000 g of colloidal silica particles.

[0131] <Example 12> A dispersion containing colloidal silica particles was obtained in the same manner as in Example 1, except that solution 5 containing colloidal silica particles and hydrogen peroxide was used instead of solution 1 containing colloidal silica particles and hydrogen peroxide.

[0132] <Comparative Example 1> As a dispersion containing colloidal silica particles for Comparative Example 1, solution 4 containing colloidal silica particles and hydrogen peroxide was prepared.

[0133] <Methods for measuring various physical properties> Various physical properties were measured in the dispersions containing colloidal silica particles of the examples and comparative examples using the following methods.

[0134] (Formaldehyde content) A dispersion containing colloidal silica particles was centrifuged (25°C, 365710G, 10 minutes), and the supernatant was collected. To 10 mL of the 10-fold diluted supernatant, 0.2 mL of a 5-fold diluted solution of 85% phosphoric acid in water was added, followed by 0.5 mL of a 1 mg / mL solution of 2,4-dinitrophenylhydrazine acetonitrile, and the mixture was mixed. The mixture was then allowed to stand for 20 minutes to obtain the test solution.

[0135] The concentration of formaldehyde was determined by measuring the test solution using high-performance liquid chromatography (HPLC) under the following conditions: HPLC measurement conditions Column: InertSustain C18 (reverse-phase column) Eluent: Acetonitrile / H2O = 50 / 50 Flow rate: 1mL / min Detection: UV360nm.

[0136] (Reduction rate of formaldehyde content) The reduction rate of formaldehyde content was calculated using the following formula: Formaldehyde content reduction rate (%) = ((AB) / A) × 100 A: Formaldehyde content (mass ppm) in a liquid containing colloidal silica particles and hydrogen peroxide. B: Formaldehyde content (mass ppm) in the dispersion containing colloidal silica particles.

[0137] Table 2 shows the types of colloidal silica particles and hydrogen peroxide-containing solutions used for ion exchange in the examples and comparative examples, the formaldehyde content in the solutions containing colloidal silica particles and hydrogen peroxide, the type of ion exchange resin and exchange group, the formaldehyde content after the ion exchange process, and the reduction rate of the formaldehyde content.

[0138] [Table 2]

[0139] As shown in Table 2, the dispersion containing colloidal silica particles in the examples shows a reduced formaldehyde content, which is produced by the reaction between hydrogen peroxide and methanol. The dispersion containing colloidal silica particles in the examples shows a higher reduction in formaldehyde content compared to the comparative example.

Claims

1. A method for producing a dispersion containing colloidal silica particles, comprising an ion exchange step of contacting a liquid containing colloidal silica particles and hydrogen peroxide with an ion exchange resin.

2. A method for producing a dispersion according to claim 1, comprising a preparation step of preparing a liquid containing colloidal silica particles and hydrogen peroxide before the ion exchange step.

3. The method for producing a dispersion according to claim 1, wherein the colloidal silica particles are colloidal silica particles produced by the alkoxide method.

4. The method for producing a dispersion according to claim 1, wherein the ion exchange resin is an anion exchange resin.

5. The method for producing the dispersion according to claim 1, wherein the colloidal silica particles include anion-modified colloidal silica particles.

6. The method for producing the dispersion according to claim 1, wherein the colloidal silica particles include sulfonic acid-modified colloidal silica particles.

7. The method for producing a dispersion according to claim 4, wherein the anion exchange resin is a strongly basic anion exchange resin.

8. The method for producing a dispersion according to claim 1, wherein the ion exchange step includes removing at least a portion of the formaldehyde in the liquid containing the colloidal silica particles and hydrogen peroxide.

9. A polishing composition comprising a dispersion produced by the manufacturing method described in claim 1.

10. A method for producing an abrasive composition comprising a dispersion containing colloidal silica particles, A method for producing an abrasive composition, comprising producing a dispersion containing colloidal silica particles by the method for producing a dispersion according to claim 1.

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