Oxide colloidal particles, sol thereof, and method for producing same

Abstract

Provided are: oxide colloidal particles which contain rutile-type titanium oxide as a main component and in which the formation of anatase-type titanium oxide is effectively suppressed; a sol containing the oxide colloidal particles; and a method for producing the oxide colloidal particles. The problem is solved by oxide colloid particles (A) comprising Ti and Sn and having an average primary particle diameter of 5-300 nm and / or a primary particle diameter of 5-300 nm in terms of both D10 and D90 in the number-based cumulative particle size distribution, wherein the numerical value of (rutile-type tin dioxide content) / (rutile-type titanium oxide content) (mass ratio) calculated by the method below is 0.3-3.5% when expressed as a percentage: (rutile-type tin dioxide content) / (rutile-type titanium oxide content) (mass ratio) = ((intensity of rutile-type tin dioxide diffraction lines in a diffraction pattern obtained by powder X-ray diffraction in a 2θ range of 20.0°-80.0°) / 9.63) / ((intensity of rutile-type titanium oxide diffraction lines in the diffraction pattern obtained by powder X-ray diffraction in the 2θ range of 20.0°-80.0°) / 3.27).

Description

Oxide colloid particles, sol thereof and method for producing the same

[0001] The present invention relates to titanium-based oxide colloidal particles, a sol thereof, and a method for producing the same, and more specifically to oxide colloidal particles, a sol thereof, and a method for producing the same that can suppress the by-production of anatase-type titanium oxide and produce the desired rutile-type titanium oxide with high purity.

[0002] Titanium oxide has three types of crystal structures: tetragonal high-temperature rutile, tetragonal low-temperature anatase, and orthorhombic brookite. Of these, rutile titanium oxide has a high refractive index and is therefore suitable for use as an optical material such as a refractive index adjuster. To be used as an optical material, not only must it have a high refractive index, but it must also be transparent when formed into a coating film. However, rutile titanium oxide is generally produced by a solid-phase method in which amorphous titanium oxide or anatase titanium oxide is calcined at high temperatures, which results in problems such as large particle size and loss of transparency.

[0003] Compared to solid-phase methods, which require high-temperature calcination, wet methods allow for low-temperature synthesis and are therefore easier to use to obtain fine particles. One example of a wet method for producing rutile-type titanium oxide sol is a method in which a titanium salt is reacted with a tin compound (rutile agent) having a rutile structure. For example, Patent Document 1 discloses a method in which a strong titanium acid salt is reacted with metallic tin in the presence of hydrogen peroxide to produce a titanium oxide-tin oxide composite colloidal aggregate at 50 to 100°C. Patent Document 2 also discloses a method in which a tin oxalate aqueous solution, titanium alkoxide, oxalic acid, a quaternary ammonium hydroxide, and water are mixed in a predetermined ratio to prepare a titanium-containing aqueous solution, and the titanium-containing aqueous solution is then hydrothermally treated at 100 to 200°C.

[0004] JP 10-245224 A International Publication No. 2012 / 111717 A1 Pamphlet

[0005] While conventional wet processes can produce rutile titanium oxide in the form of relatively fine particles, a considerable amount of anatase titanium oxide is simultaneously produced. Anatase titanium oxide has a significantly lower refractive index than rutile titanium oxide, making its production undesirable from the perspective of obtaining a homogeneous, high-refractive-index material. Furthermore, because anatase titanium oxide has photocatalytic activity, it may reduce the photostability of a dispersion containing titanium oxide fine particles, so suppressing its production has been desirable. In light of the limitations of the above-mentioned conventional technologies, an object of the present invention is to provide oxide colloidal particles primarily composed of rutile titanium oxide, in which the production of anatase titanium oxide is effectively suppressed, a sol containing the oxide colloidal particles, and a method for producing the oxide colloidal particles.

[0006] As a result of extensive research into solving the above problems, the present inventors have found that a part of the tin compound used as a rutile forming agent is a single SnO ２ Furthermore, the inventors have found that the tin compound remains as an anatase type titanium oxide by improving the solid solution ratio of the tin compound to the titanium oxide. ２ The present inventors have found that the formation of anatase-type titanium oxide can be effectively suppressed by controlling and suppressing the formation of anatase-type titanium oxide, more specifically by keeping the ratio (rutile-type stannic oxide content) / (rutile-type titanium oxide content) calculated by the RIR method within a predetermined range, and have completed the present invention.

[0007] That is, the present invention and its embodiments are as follows: [1] Oxide colloidal particles (A) containing Ti and Sn, having an average primary particle diameter of 5 nm to 300 nm and / or a primary particle diameter in which the cumulative particle size distributions D10 and D90 based on number are both 5 nm to 300 nm, wherein the (rutile-type stannic oxide content) / (rutile-type titanium oxide content) (mass ratio), calculated as a percentage by the following method, is 0.3 to 3.5%: (rutile-type stannic oxide content) / (rutile-type titanium oxide content) (mass ratio)=((diffraction line intensity of rutile-type stannic oxide in a diffraction pattern obtained by powder X-ray diffraction measurement in the range of 2θ = 20.0 to 80.0°) / 9.63) / (diffraction line intensity of rutile-type titanium oxide in a diffraction pattern obtained by powder X-ray diffraction measurement in the range of 2θ = 20.0 to 80.0°) / 3.27. [2] Oxide colloidal particles (A) according to [1], wherein the value calculated from a diffraction pattern obtained by powder X-ray diffraction method, (the diffraction peak area derived from the (101) plane of rutile-type stannic oxide) / (the diffraction peak area derived from the (101) plane of rutile-type titanium oxide), expressed as a percentage, is 1.0 to 40%. [3] Oxide colloidal particles (A) according to [1] or [2], wherein the volume-based cumulative particle size distribution D90 - the cumulative particle size distribution D10, as measured by dynamic light scattering, of the oxide colloidal particles (A) is 5 to 30 (nm), and the standard deviation of the average particle diameter is 1.5 to 10 (nm). [4] Coated colloidal particles (B / A), in which the surfaces of the oxide colloidal particles (A) according to any one of [1] to [3] are coated with a metal oxide (B) containing a metal oxide component other than titanium oxide. [5] Coated colloidal particles (B / A) according to [4], wherein the metal oxide (B) contains at least one selected from the group consisting of silicon dioxide, tin oxide, antimony oxide, tungsten oxide, aluminum oxide, and zirconium oxide. [6] Coated colloidal particles (B / A) according to either [4] or [5], wherein the metal oxide (B) contains a silicon dioxide-stannic oxide composite oxide having a silicon dioxide / stannic oxide mass ratio of 0.1 to 5.0, and which have a colloidal particle form with an average primary particle size of 1 to 20 nm.[7] The coated colloidal particles (B / A) according to any one of [4] to [6], wherein the ratio of (mass of metal oxide (B)) / (mass of oxide colloidal particles (A)) is 0.05 to 0.50. [8] The coated colloidal particles (A) according to any one of [1] to [3], wherein the refractive index of the oxide colloidal particles (A) is 2.0 to 2.6. [9] The coated colloid particles (B / A) according to any one of [4] to [7], wherein an aqueous colloidal solution is formed containing the coated colloid particles (B / A), 6-hydroxy-5-[(4-sulfophenyl)azo]-2-naphthalenesulfonate disodium dye (E), water, methanol, and glycerin in amounts such that the mass ratio of the coated colloid particles (B / A):dye (E) is 1:0.12:99.5:99.5:599.88, and the aqueous colloidal solution is irradiated with light of a wavelength of 365 nm at 0.4 mW / cm. ２

[10] The oxide colloid particles (A) according to any one of [1] to [3] and [8], wherein the particle surface is further coated with an amine.

[11] The oxide colloid particles (A) according to any one of [1] to [3], [8] and

[10] , wherein the oxide colloid particles (A) containing Ti and Sn are oxide colloid particles obtained by a sol-gel method using a titanium alkoxide as the titanium-containing compound.

[12] The oxide colloid particles (A) according to any one of [1] to [3], [8] and

[10] , wherein the surface of the oxide colloid particles (A) is coated with a hydrolyzable silane (1) having a structure represented by the following formula (1): (In the formula, R １ represents an alkyl group, an aryl group, a halogenated alkyl group, a halogenated aryl group, an alkenyl group, or an organic group having an acryloyl group, a methacryloyl group, a mercapto group, a ureido group, an amino group, or a cyano group, and is bonded to a silicon atom via a Si—C bond; R ２represents an alkoxy group, an acyloxy group, or a halogen group, and a represents an integer of 1 to 3.) The oxide colloid particles (A) according to any one of [1] to [3], [8],

[10] , and

[11] , which are coated with a hydroxy group.

[13] A sol of the oxide colloid particles (A) and / or the coated colloid particles (B / A) according to any one of [1] to [3], [8], and

[10] to

[12] , and / or the coated colloid particles (B / A) according to any one of [4] to [7], and [9], dispersed in a liquid medium as a dispersoid, wherein the sol has an average particle size of 5 to 500 nm as measured by a dynamic light scattering method.

[14] The sol according to

[13] , wherein the liquid medium is an organic solvent.

[15] The sol according to

[13] or

[14] , further containing an amine.

[16] A method for producing an aqueous sol of coated colloidal particles (B / A), comprising the following step (a): Step (a): A step of mixing an aqueous sol containing the oxide colloidal particles (A) according to any one of items [1] to [3], [8], and

[10] to

[12] with an aqueous sol containing a metal oxide (B) containing a metal oxide component other than titanium oxide, in a mass ratio (B) / (A) of 0.05 to 0.50, to obtain an aqueous sol of coated colloidal particles (B / A) in which the metal oxide (B) is coated on the oxide colloidal particles (A).

[17] A method for producing an aqueous sol of coated colloid particles (B / A) according to

[16] , further comprising at least one step selected from the group consisting of the following steps (b) and (c) after the step (a): step (b): ultrafiltrating the aqueous sol of coated colloid particles (B / A) obtained in step (a), step (c): subjecting the aqueous sol of coated colloid particles (B / A) obtained in step (a) to cation exchange and / or anion exchange.

[18] A method for producing an organic solvent sol of coated colloid particles (B / A), further comprising the following step (d) after the step (a) according to

[16] : step (d): replacing the aqueous solvent of the aqueous sol of coated colloid particles (B / A) obtained in step (a) with an organic solvent.

[19] A method for producing an organic solvent sol of coated colloidal particles (B / A), comprising the following step (d') after the step (b) or step (c) according to

[17] : step (d'): a step of solvent-substituting an organic solvent for the aqueous solvent of the aqueous sol of coated colloidal particles (B / A) obtained in the step (b) or step (c).

[0008] According to the present invention, it is possible to realize rutile-type oxide colloidal particles, a sol containing said oxide colloidal particles, and a method for producing said oxide colloidal particles, which effectively suppress the generation of anatase-type titanium oxide and which combine at a high level, beyond the limits of conventional techniques, various properties that are highly valuable in practice, such as a high refractive index, high homogeneity, high photostability, and a fine particle size.

[0009] The present invention relates to oxide colloidal particles (A) containing Ti and Sn, which have an average primary particle size of 5 nm to 300 nm and / or primary particle sizes in which the cumulative particle size distributions D10 and D90 based on number are both 5 nm to 300 nm, in which the percentage of (rutile-type stannic oxide content) / (rutile-type titanium oxide content) (mass ratio), calculated according to the following formula (1), is 0.3 to 3.5%: (rutile-type stannic oxide content) / (rutile-type titanium oxide content) (mass ratio)=((diffraction line intensity of rutile-type stannic oxide in a diffraction pattern obtained by powder X-ray diffraction measurement in the 2θ=20.0 to 80.0° range) / 9.63) / (diffraction line intensity of rutile-type titanium oxide in a diffraction pattern obtained by powder X-ray diffraction measurement in the 2θ=20.0 to 80.0° range) / 3.27)-(1).

[0010] Oxide colloid particles (A) As described above, the oxide colloid particles (A) of the present invention are oxide colloid particles containing Ti and Sn. While the Ti content in the oxide colloid particles (A) is not particularly limited, from the viewpoint of uniformly forming the rutile-type titanium oxide targeted by the present invention, it is preferable that Ti be the main component, and that the Ti content be 70% by mass or more, more preferably 75% by mass or more, and particularly preferably 80% by mass or more, based on the mass of Ti oxide. While the Sn content in the oxide colloid particles (A) is not particularly limited, from the viewpoint of inhibiting the formation of a single rutile-type stannic oxide phase, it is preferably 30% by mass or less, more preferably 25% by mass or less, and particularly preferably 20% by mass or less, based on the mass of Sn oxide. On the other hand, from the viewpoint of allowing the tin compound to effectively function as a rutile-forming agent, the Sn content in the oxide colloid particles (A) is preferably 5% by mass or more, and particularly preferably 10% by mass or more, based on the mass of Sn oxide.

[0011] The Ti content and Sn content in the oxide colloidal particles (A) can be measured by a conventionally known method, for example, by X-ray fluorescence (XRF) analysis. More specifically, they can be measured by the method described in the examples of the present application. The Ti content and Sn content in the oxide colloidal particles (A) can be appropriately controlled by the type and amount of titanium alkoxide or the like used as a Ti source, the type and amount of tin compound (rutile agent) or the like used, the production conditions of the oxide colloidal particles (A), etc.

[0012] The mass ratio (rutile stannic oxide content) / (rutile titanium oxide content) of the oxide colloidal particles, calculated according to the above formula (1), is 0.3 to 3.5%, preferably 0.3 to 3.0%, more preferably 0.3 to 2.5%, and particularly preferably 0.5 to 2.5%. When the mass ratio (rutile stannic oxide content) / (rutile titanium oxide content) is within the range of 0.3 to 3.5%, the oxide colloidal particles (A) of the present invention effectively suppress the formation of anatase titanium oxide, and can achieve high levels of various properties that are highly valuable in practice, such as a high refractive index, high homogeneity, high photostability, and a fine particle size, exceeding the limits of conventional technology.

[0013] The calculation of the mass ratio of (rutile-type stannic oxide content) / (rutile-type titanium oxide content) using the above formula (1) is in accordance with the so-called RIR (Reference Intensity Ratio) method, and more specifically, is based on the following principle: ｉ When the RIR value R of the substance is given, the mass ratio of the substance to the sample can be calculated using the integrated intensity of the maximum peak of the substance in the diffraction pattern obtained by measuring in the range of 2θ = 20.0 to 80.0 degrees by powder X-ray diffraction. ｉ The material and corundum (Al ２ O ３ ) at a mass ratio of 1:1. ｉ ｍａｘ More specifically, the mass ratio of the substance to Corundum is defined as W ｉ :W ｃ In this case, the relationship of the following formula (2) is established. W ｉ : mass ratio of the substance W Ｃ : Mass ratio of corundum I ｉ ｍａｘ : Integrated intensity of the maximum peak of the substance in the diffraction pattern obtained by measuring in the range of 2θ = 20.0 to 80.0 ° ｃ ｍａｘ: Integrated intensity of the maximum peak of corundum in the diffraction pattern obtained by measuring in the range of 2θ = 20.0 to 80.0 ° R ｉ : RIR value of the substance. Therefore, a mixture of the substance and corundum with a known mass ratio is measured by powder X-ray diffraction in the range of 2θ = 20.0 to 80.0 °, and the integrated intensity I of the maximum peak of the substance in the obtained diffraction pattern is ｉ ｍａｘ and the integrated intensity I of the maximum peak of corundum ｃ ｍａｘ From the above, the RIR value R of the substance is calculated according to the formula (2). ｉ As will be described later, the RIR values ​​of many substances are available in publicly available databases.

[0014] The relationship of the following formula (3) can be derived from the above formula (2): ｉ is the integrated intensity I of the maximum peak of the substance ｉ ｍａｘ is the RIR value R of the substance ｉ Since it is proportional to the value divided by , the RIR value R of the substance i is ｉ and maximum peak intensity I ｉ ｍａｘ Using the mass ratio W ｉ It is possible to ask for: If the intensity ratio of another diffraction peak to the maximum peak can be determined by measuring the integrated intensity of another diffraction peak of the substance, the maximum peak intensity I ｉ ｍａｘ Even if it is not possible to determine the mass ratio, the mass ratio can be calculated in the same manner.

[0015] As mentioned above, the RIR value R of the substance i ｉ and maximum peak intensity I ｉ ｍａｘ Using the mass ratio W ｉcan be obtained, and accordingly, the ratio (rutile stannic oxide content) / (rutile titanium oxide content) (mass ratio) can be obtained. The above formula (1) is based on this relationship, and can be more generally expressed by the following formula (4): (rutile stannic oxide content) / (rutile titanium oxide content) (mass ratio)=((diffraction line intensity of rutile stannic oxide in a diffraction pattern obtained by measurement using powder X-ray diffraction in the range of 2θ=20.0 to 80.0°) / RIR value of rutile stannic oxide) / (diffraction line intensity of rutile titanium oxide in a diffraction pattern obtained by measurement using powder X-ray diffraction in the range of 2θ=20.0 to 80.0°) / RIR value of rutile titanium oxide)-(4) The above formula (1) can be obtained by substituting the RIR value of 9.63 for rutile stannic oxide and the RIR value of 3.27 for rutile titanium oxide into the above formula (4). The mass ratio of (rutile-type stannic oxide content) / (rutile-type titanium oxide content) according to formula (1) is based on the principle of the RIR method described above, and therefore excludes stannic oxide dissolved in rutile-type titanium oxide, making it possible to evaluate the content of stannic oxide remaining as rutile-type stannic oxide alone.

[0016] The mass ratio of (rutile-type stannic oxide content) / (rutile-type titanium oxide content) calculated according to the above formula (1) can be controlled, for example, by appropriately adjusting the type, production method, and amount of the tin compound used as the rutile agent, the production conditions for the oxide colloidal particles, etc. More specifically, the mass ratio of (rutile-type stannic oxide content) / (rutile-type titanium oxide content) can be reduced by using, as the rutile agent, an aqueous tin oxalate solution, an aqueous tin malonate solution, or an aqueous tin succinate solution obtained by dissolving metal tin powder using hydrogen peroxide and oxalic acid, malonic acid, or succinic acid. Furthermore, when using the above tin oxalate aqueous solution, the mass ratio of (rutile-type stannic oxide content) / (rutile-type titanium oxide content) can be further reduced by maintaining at least a portion of the hydrogen peroxide. More specifically, when the tin oxalate aqueous solution is mixed with a titanium source such as titanium alkoxide, the mass ratio of (rutile-type stannic oxide content) / (rutile-type titanium oxide content) can be further reduced by maintaining the tin oxalate aqueous solution in a state in which it contains hydrogen peroxide.

[0017] By maintaining at least a portion of the hydrogen peroxide, the solubility of tin oxide is improved, so the amount of rutile stannic oxide alone is reduced, and the mass ratio (content of rutile stannic oxide) / (content of rutile titanium oxide) can be further reduced. For example, by maintaining a state in which hydrogen peroxide is contained until just before autoclaving, fine rutile stannic oxide particles produced as a by-product during the reaction are re-dissolved in the solvent, facilitating solid dissolution into titanium oxide particles, and the mass ratio (content of rutile stannic oxide) / (content of rutile titanium oxide) can be further reduced.

[0018] From the viewpoint of effectively suppressing the formation of anatase-type titanium oxide, the value expressed as a percentage of (rutile-type stannic oxide content) / (rutile-type titanium oxide content) (mass ratio), calculated according to the above formula (1), is preferably 3.0% or less, and particularly preferably 2.5% or less. From the viewpoint of suppressing particle growth of rutile-type titanium oxide and minimizing the particle size, the value expressed as a percentage of (rutile-type stannic oxide content) / (rutile-type titanium oxide content) (mass ratio), calculated according to the above formula (1), is preferably 0.4% or more, and particularly preferably 0.5% or more.

[0019] The value obtained by calculating the (diffraction peak area derived from the (101) plane of rutile-type stannic oxide) / (diffraction peak area derived from the (101) plane of rutile-type titanium oxide) from the diffraction pattern obtained by powder X-ray diffraction of the oxide colloidal particles (A) of the present invention, expressed as a percentage, is preferably 1.0 to 40%, more preferably 1.0 to 30%, and particularly preferably 1.0 to 20%. When the ratio of the (diffraction peak area derived from the (101) plane of rutile-type stannic oxide) / (diffraction peak area derived from the (101) plane of rutile-type titanium oxide) calculated from the diffraction pattern obtained by powder X-ray diffraction of the oxide colloidal particles (A) is 1.0 to 40%, the formation of anatase-type titanium oxide can be more effectively suppressed, and thereby each of the properties having high practical value, such as a high refractive index, high homogeneity, high photostability, and a fine particle size, can be realized at an even higher level, which is preferable.

[0020] The ratio of (diffraction peak area originating from the (101) plane of rutile-type stannic oxide) / (diffraction peak area originating from the (101) plane of rutile-type titanium oxide) can be calculated by separating the diffraction peak originating from the (101) plane of rutile-type stannic oxide and the diffraction peak originating from the (101) plane of rutile-type titanium oxide near 2θ=35 degrees in the X-ray diffraction pattern of the oxide colloidal particles, and calculating the area ratio of the two peaks. Since the ratio of (diffraction peak area originating from the (101) plane of rutile-type stannic oxide) / (diffraction peak area originating from the (101) plane of rutile-type titanium oxide) is based on the specific crystal structure of rutile-type stannic oxide and the specific crystal structure of rutile-type titanium oxide, as described above, the influence of stannic oxide solid-solubilized in rutile-type titanium oxide is excluded from the molecule (diffraction peak area originating from the (101) plane of rutile-type stannic oxide), and the content of stannic oxide remaining as a single rutile-type stannic oxide can be evaluated.

[0021] The ratio of (diffraction peak area derived from the (101) plane of rutile-type stannic oxide) / (diffraction peak area derived from the (101) plane of rutile-type titanium oxide) can be appropriately adjusted by, for example, adjusting the type, production method, and amount of tin compound used as the rutile agent, the production conditions for the oxide colloidal particles, etc. More specifically, the ratio of (diffraction peak area derived from the (101) plane of rutile-type stannic oxide) / (diffraction peak area derived from the (101) plane of rutile-type titanium oxide) can be reduced by using, as the rutile-type agent, an aqueous solution of tin oxalate, an aqueous solution of tin malonate, an aqueous solution of tin succinate, or the like, in which metal tin powder is dissolved using hydrogen peroxide and oxalic acid. Furthermore, when using the above-mentioned aqueous solution of tin oxalate, the ratio of (diffraction peak area derived from the (101) plane of rutile-type stannic oxide) / (diffraction peak area derived from the (101) plane of rutile-type titanium oxide) can be further reduced by maintaining at least a portion of the hydrogen peroxide. More specifically, when the tin oxalate aqueous solution is mixed with a titanium source such as titanium alkoxide, the proportion of the diffraction peak area derived from the (101) plane of rutile titanium oxide can be further reduced by maintaining the tin oxalate aqueous solution in a state in which it contains hydrogen peroxide. By maintaining the state in which it contains hydrogen peroxide until just before autoclaving, the proportion of the diffraction peak area derived from the (101) plane of rutile titanium oxide can be further reduced.

[0022] From the viewpoint of refractive index, the ratio of (diffraction peak area derived from the (101) plane of rutile-type stannic oxide) / (diffraction peak area derived from the (101) plane of rutile-type titanium oxide) is more preferably 40% or less, and particularly preferably 20% or less. From the viewpoint of effectively suppressing the formation of anatase-type titanium oxide, the ratio of (diffraction peak area derived from the (101) plane of rutile-type stannic oxide) / (diffraction peak area derived from the (101) plane of rutile-type titanium oxide) is more preferably 1.0% or more, and particularly preferably 5.0% or more.

[0023] The oxide colloidal particles (A) of the present invention have an average primary particle size and / or primary particle size (D10 and D90) of 5 nm to 300 nm. By having an average primary particle size and / or primary particle size (D10 and D90) of 5 nm to 300 nm, the oxide colloidal particles (A) of the present invention have good dispersibility and can stably form a dispersion or sol, can form a uniform and dense coating, and can achieve desirable properties such as high transparency.

[0024] The primary particle diameter of the oxide colloid particles (A) of the present invention is measured by observation with a transmission electron microscope. More specifically, it can be measured, for example, by the method described in the Examples of the present application. The primary particle diameter of the oxide colloid particles (A) of the present invention is preferably 5 nm to 100 nm, more preferably 5 nm to 50 nm, and particularly preferably 5 nm to 20 nm. The primary particle diameter of the oxide colloid particles (A) of one embodiment of the present invention is 5 nm to 300 nm, with the cumulative particle size distribution D10 based on the number of equivalent circle diameters as the lower limit. Therefore, D10 is 5 nm or more. D10 is preferably 5 nm or more, 7 nm or more, or 10 nm or more. Furthermore, the primary particle diameter of the oxide colloid particles (A) of the present invention is measured with the cumulative particle size distribution D90 based on the number of equivalent circle diameters as the upper limit. Therefore, D90 is 300 nm or less. D90 is preferably 100 nm or less, 50 nm or less, or 20 nm or less. That is, the primary particle diameters of the oxide colloid particles (A) are, in terms of D10 and D90, 5 nm to 300 nm, preferably 5 nm to 100 nm, more preferably 5 nm to 50 nm, and particularly preferably 5 nm to 20 nm. Furthermore, the average primary particle diameter of the oxide colloid particles (A) of the present invention can be calculated from the particle size distribution based on the number of equivalent circle diameters. The average primary particle diameter of the oxide colloid particles (A) of the present invention can be 5 to 300 nm, preferably 5 nm to 100 nm, more preferably 5 nm to 50 nm, and particularly preferably 5 nm to 20 nm.

[0025] The volume-based cumulative particle size distribution D90 - the cumulative particle size distribution D10 of the oxide colloidal particles (A) of the present invention, as measured by dynamic light scattering, is preferably 5 to 30 nm. When the volume-based cumulative particle size distribution D90 - the cumulative particle size distribution D10 of the oxide colloidal particles (A) is 5 to 30 nm, the oxide colloidal particles (A) of this embodiment have a relatively uniform particle size distribution, and the above-mentioned technical effects of the present invention, such as good dispersibility and high transparency, can be more effectively achieved. The volume-based cumulative particle size distribution D90 - the cumulative particle size distribution D10 of the oxide colloidal particles (A) as measured by dynamic light scattering is more preferably 5 to 25 nm, and particularly preferably 6 to 20 nm.

[0026] The standard deviation of the average particle size of the oxide colloidal particles (A) of the present invention, as measured by dynamic light scattering, is preferably 1.5 to 10 (nm). Since the standard deviation of the average particle size of the oxide colloidal particles (A) as measured by dynamic light scattering is 1.5 to 10 (nm), the oxide colloidal particles (A) of this embodiment have a relatively uniform particle size distribution, and the above-mentioned technical effects of the present invention, such as good dispersibility and high transparency, can be more effectively achieved. The standard deviation of the average particle size of the oxide colloidal particles (A) as measured by dynamic light scattering is preferably 1.5 to 8.0 nm, more preferably 1.5 to 5.0 nm, and particularly preferably 1.5 to 3.0 nm. It is particularly preferable that the volume-based cumulative particle size distribution D90 - cumulative particle size distribution D10 of the oxide colloidal particles (A) as measured by dynamic light scattering is 5 to 30 (nm), and the standard deviation of the average particle size is 1.5 to 10 (nm).

[0027] The average primary particle size of the oxide colloidal particles (A) as determined by a dynamic light scattering method, the volume-based cumulative particle size distribution D90-the cumulative particle size distribution D10, and the standard deviation of the average particle size can be controlled by appropriately setting the production conditions of the oxide colloidal particles (A), such as the type and amount of the titanium source, the rutilating agent, etc., the production method of the rutilating agent, the temperature, time, concentration, etc. of the hydrothermal treatment.

[0028] The refractive index of the oxide colloidal particles (A) is not particularly limited, but is preferably 2.0 to 2.6. By having a refractive index of 2.0 to 2.6, the oxide colloidal particles (A) of this embodiment can form an optical coating with a high refractive index, and since the refractive index can be adjusted even with a small amount added, it is possible to achieve favorable effects such as excellent economy and composition improvement. The refractive index of the oxide colloidal particles (A) is more preferably 2.1 to 2.6, and particularly preferably 2.2 to 2.6. The refractive index of the oxide colloidal particles (A) can be adjusted by appropriately setting the crystalline form and proportion of titanium oxide, crystallinity, etc.

[0029] There is no particular limitation on the method for producing the oxide colloidal particles (A), but it is preferable to produce them by a sol-gel method using a titanium alkoxide as the titanium-containing compound. There is also no particular limitation on the titanium alkoxide, but it is particularly preferable to use a tetraalkoxytitanium having an alkoxyl group with 1 to 3 carbon atoms. This tetraalkoxytitanium has a structure represented by the following general formula (i): Ti(OR 1 ) ４ - (i) In formula (i), each R 1 are the same or different alkyl groups having 1 to 3 carbon atoms. In the above-mentioned tetraalkoxytitanium, the four alkoxyl groups may be the same or different, but from the viewpoint of ease of availability, it is preferable to use the same ones. Specific examples of the tetraalkoxytitanium include tetramethoxytitanium, tetraethoxytitanium, tetra-n-propoxytitanium, titanium tetraisopropoxide, and titanium tetrabutoxide. These may be used alone or in combination of two or more.

[0030] The steps of the sol-gel method are not particularly limited, but a method can be used in which a tin compound (rutile agent), titanium alkoxide, oxalic acid, quaternary ammonium hydroxide, water, etc. are mixed and heated to dissolve, followed by hydrothermal treatment. The order in which the tin compound (rutile agent), titanium alkoxide, oxalic acid, quaternary ammonium hydroxide, water, etc. are mixed is not particularly limited. The ratios of the tin compound (rutile agent), titanium alkoxide, and oxalic acid to be mixed are also not particularly limited, but it is preferable to adjust them so that, for example, the ratio of tin atoms is 0.025 to 0.8 moles and the ratio of oxalic acid is 0.01 to 5 moles per mole of titanium atoms, respectively.

[0031] There are no particular limitations on the tin compound (rutile agent), but it is preferable to use tin oxalate. There are also no particular limitations on the method for producing tin oxalate, but it can be produced by reacting metallic tin, oxalic acid, and hydrogen peroxide in an aqueous medium. The resulting tin oxalate aqueous solution contains residual hydrogen peroxide, but by maintaining the tin oxalate aqueous solution in a state where it contains hydrogen peroxide, it is possible to promote the solid solution of the tin compound used as the rutile agent into titanium oxide, and to obtain a tin compound containing SnO alone. ２ This effectively prevents the residual of titanium alkoxide, oxalic acid, quaternary ammonium hydroxide, water, etc. More specifically, in the step of mixing titanium alkoxide, oxalic acid, quaternary ammonium hydroxide, water, etc., and the step of dissolving by heating, the mixed solution preferably contains hydrogen peroxide. More specifically, the hydrogen peroxide concentration in these steps is preferably 0.05 to 3.00 mass %, more preferably 0.1 to 1.00 mass %. From the viewpoint of particle growth during hydrothermal treatment, hydrogen peroxide may be removed between the step of dissolving by heating and the step of hydrothermal treatment. Hydrogen peroxide can be removed by passing the mixed solution through a column packed with a platinum-supported oxidation catalyst.

[0032] The conditions for the heat-dissolving step are not particularly limited, but it is preferable to heat-dissolve at a temperature of 50 to 100°C, more preferably 70 to 95°C, for 1 to 10 hours, more preferably 2 to 8 hours. Stirring may be performed during the heat-dissolving. The conditions for the hydrothermal treatment step are also not particularly limited, but the mixed solution obtained in the heat-dissolving step can be filled into a pressure-resistant container and subjected to the hydrothermal treatment. From the viewpoints of promoting crystallization of the oxide colloidal particles and suppressing aggregation of the oxide colloidal particles, the hydrothermal treatment temperature is preferably 100 to 200°C, more preferably 120 to 180°C. The hydrothermal treatment time is preferably 0.5 to 10 hours, more preferably 1 to 6 hours.

[0033] The oxide colloidal particles (A) of the present invention may be used as they are, or may be dispersed alone in a dispersion medium to form a sol, but the surface may be coated from the viewpoints of chemical stability, dispersibility, compatibility with resins, etc. For example, from the viewpoint of dispersibility, etc., it is preferable to coat the surface of the oxide colloidal particles (A) with a hydrolyzable silane having a structure represented by the following general formula (ii): In formula (ii), R １ represents an organic group having an alkyl group, an aryl group, a halogenated alkyl group, a halogenated aryl group, an alkenyl group, a polyether group, an epoxy group, an acryloyl group, a methacryloyl group, a mercapto group, a ureido group, an amino group, or a cyano group, and is bonded to a silicon atom via a Si—C bond; R ２ represents an alkoxy group, an acyloxy group, or a halogen group, and a represents an integer of 1 to 3. １ is preferably an alkyl group having 1 to 50 carbon atoms, an epoxy group, an acryloyl group, a methacryloyl group, or a ureido group, and particularly preferably an alkyl group having 1 to 12 carbon atoms, an epoxy group, or a methacryloyl group. ２is preferably a methoxy group or ethoxy group having 1 to 2 carbon atoms, and particularly preferably a methoxy group. a is preferably 1 to 2. There are no particular restrictions on the amount of hydrolyzable silane used, but from the viewpoints of dispersibility, refractive index, etc., the ratio of (mass of hydrolyzable silane) / (mass of oxide colloidal particles (A)) is preferably 0.01 to 0.30, more preferably 0.02 to 0.30, even more preferably 0.02 to 0.25, even more preferably 0.02 to 0.20, and particularly preferably 0.03 to 0.15. The ratio of (mass of hydrolyzable silane) / (mass of oxide colloidal particles (A)) can be controlled by appropriately adjusting the types and amounts of oxide colloidal particles (A) and hydrolyzable silane used in coating formation, the conditions of the coating formation process, etc. In addition, the surfaces of the oxide colloidal particles (A) may be coated with an amine. In this case, the amine is not particularly limited, but for example, various amines described below as amines used in the sol of the oxide colloidal particles (A) or the coated colloidal particles (B / A) can be preferably used.

[0034] Coated Colloidal Particles (B / A) It is also preferable to form coated colloidal particles (B / A) by coating the surfaces of oxide colloidal particles (A) with a metal oxide (B) of a metal oxide component other than titanium oxide. It is particularly preferable that the coated colloidal particles (B / A) have a so-called core / shell structure in which the core of the oxide colloidal particle (A) is coated with a shell of metal oxide (B). The metal oxide (B) may contain a metal oxide component other than titanium oxide, and no other limitations are imposed on the constituent components. However, from the viewpoint of color tone, etc., it is preferable that it contains at least one selected from the group consisting of silicon dioxide, tin oxide, antimony oxide, tungsten oxide, aluminum oxide, and zirconium oxide. Among these, from the viewpoint of bonding with a surface treatment agent, etc., it is more preferable that it contains at least one selected from the group consisting of silicon dioxide and tin oxide, and it is particularly preferable that it contains a silicon dioxide-stannic oxide composite oxide.

[0035] When the metal oxide (B) contains a silicon dioxide-stannic oxide composite oxide, there are no particular restrictions on the ratio of silicon dioxide to stannic oxide, but from the viewpoint of dispersibility and the like, the mass ratio of silicon dioxide to stannic oxide is preferably 0.1 to 5.0, more preferably 0.5 to 4.0, and particularly preferably 1.0 to 3.0. There are also no particular restrictions on the particle size and form of the metal oxide (B), but from the viewpoint of shell compactness and the like, it is preferably in the form of colloidal particles having an average primary particle size of 1 to 5 nm. The average primary particle size of the colloidal particles is more preferably 1.0 to 3.0 nm, and particularly preferably 1.0 to 2.0 nm.

[0036] The ratio of the oxide colloidal particles (A) to the metal oxide (B) in the coated colloidal particles (B / A) is not particularly limited, but from the viewpoint of refractive index and the like, the ratio of (mass of metal oxide (B)) / (mass of oxide colloidal particles (A)) is preferably 0.05 to 0.50. The ratio of (mass of metal oxide (B)) / (mass of oxide colloidal particles (A)) can be controlled by appropriately adjusting the types and amounts of the oxide colloidal particles (A) and metal oxide (B) used in producing the coated colloidal particles (B / A), the production conditions for the coated colloidal particles (B / A), and the like. The ratio of (mass of metal oxide (B)) / (mass of oxide colloidal particles (A)) is more preferably 0.075 to 0.50, even more preferably 0.10 to 0.50, and particularly preferably 0.15 to 0.40. There are no particular limitations on the particle size and form of the coated colloidal particles (B / A), but they are preferably in the form of colloidal particles having an average primary particle size of 1 to 20 nm, more preferably 1 to 10 nm.

[0037] The coated colloidal particles (B / A) of this embodiment effectively suppress the generation of anatase-type titanium oxide having photocatalytic activity in the oxide colloidal particles (A), and further have a coating of metal oxide (B), thereby enabling the formation of a dispersion or sol having high photostability. More specifically, an aqueous colloidal solution is formed containing the coated colloidal particles (B / A), a dye (E) which is disodium 6-hydroxy-5-[(4-sulfophenyl)azo]-2-naphthalenesulfonate, water, methanol, and glycerin in amounts such that the mass ratio of the coated colloidal particles (B / A):dye (E):water:methanol:glycerin is 1:0.12:99.5:99.5:599.88, and the aqueous colloidal solution is irradiated with I-rays (wavelength 365 nm) at 0.4 mW / cm. ２ The change in absorbance (rate of fading) at the maximum absorption wavelength (490 nm) of the dye (E) in the aqueous colloidal solution after 180 minutes of irradiation with 1000 kJ / cm² can be significantly reduced compared to the prior art. The change in absorbance (rate of fading) is defined by the following formula (5) and can be measured, for example, by the method described in the Examples of the present application. Rate of fading (%) = (1 - (A １８０ ) / (A ０ ))×100 - (5) A ０ A: absorbance at a wavelength of 490 nm before irradiation with I-rays (wavelength 365 nm) １８０ : absorbance at a wavelength of 490 nm after irradiation with I-rays (wavelength 365 nm) for 180 minutes The above absorbance change (discoloration change rate) is preferably less than 10%, more preferably 0.1 to 9.0%, even more preferably 5.0% or less, and particularly preferably 3.0% or less. The smaller the above absorbance change (discoloration change rate), the better, and therefore there is no particular lower limit. However, slight discoloration may occur even when only the dye is used without adding the coated colloidal particles (B / A), and the change is often 0.1% or more, and more commonly 0.5% or more, 0.7% or more, or 1.0% or more.

[0038] The coated colloidal particles (B / A) may be oxide colloidal particles (A) whose surfaces are directly coated with metal oxide (B), or an intermediate layer may be provided between the oxide colloidal particles (A) and the metal oxide (B). There are no particular restrictions on the material of the intermediate layer, but from the viewpoint of transparency, ZrO ２ , ZnO, Al ２ O ３ The amount of the intermediate layer is not particularly limited, but from the viewpoint of refractive index and the like, the ratio of (mass of intermediate layer) / (mass of oxide colloid particles (A)) is preferably 0.5 to 30.0, and particularly preferably 10.0 to 20.0.

[0039] Sol of Oxide Colloid Particles (A) or Coated Colloid Particles (B / A) A sol can be formed by dispersing the oxide colloid particles (A) and / or coated colloid particles (B / A) as a dispersoid in a liquid medium. In the sol, the oxide colloid particles (A) and / or coated colloid particles (B / A) preferably form secondary particles, resulting in an average particle size of 5 to 500 nm as measured by dynamic light scattering (DLS). The average particle size is more preferably 5 to 200 nm, even more preferably 5 to 100 nm, even more preferably 10 to 100 nm, even more preferably 10 to 50 nm, and particularly preferably 15 to 30 nm. By measuring the average particle size of 5 to 500 nm as measured by dynamic light scattering, the sol containing the oxide colloid particles (A) and / or coated colloid particles (B / A) has a more uniform particle size distribution, and the technical effects of the present invention, such as good dispersibility and high transparency, can be more effectively achieved.

[0040] The dispersion medium constituting the sol of the oxide colloidal particles (A) or the coated colloidal particles (B / A) is not particularly limited, but is preferably an organic solvent from the viewpoint of the film-forming properties of the coating composition, compatibility with the binder, etc. Preferred examples of the organic solvent include methanol, methyl ethyl ketone, propylene glycol monomethyl ether, and propylene glycol monomethyl ether acetate.

[0041] In addition to the oxide colloidal particles (A) and / or the coated colloidal particles (B / A) and the dispersion medium, the sol may contain an amine from the viewpoints of sol stabilization, pH adjustment, etc. As the amine, alkylamines such as ethylamine, diethylamine, n-propylamine, isopropylamine, diisopropylamine, dipropylamine, n-butylamine, isobutylamine, diisobutylamine, triethylamine, and benzylamine, and alkanolamines such as monoethanolamine and triethanolamine can be preferably used. Among these, diisopropylamine, diisobutylamine, and the like are particularly preferably used. There are no particular restrictions on the amount of amine used, but from the viewpoint of refractive index, etc., the concentration in the sol is preferably 0.1 to 2.0% by mass, and particularly preferably 0.3 to 1.0% by mass.

[0042] The method for producing an aqueous sol of coated colloidal particles (B / A) is not particularly limited, but the coated colloidal particles (B / A) can be preferably produced by a production method including the following step (a): Step (a): Mixing an aqueous sol containing oxide colloidal particles (A) and an aqueous sol containing metal oxide (B) at a mass ratio (B) / (A) of 0.05 to 0.50 to obtain an aqueous sol of coated colloidal particles (B / A) in which the metal oxide (B) coats the oxide colloidal particles (A) as a shell. Here, the oxide colloidal particles (A) are, as described above, oxide colloidal particles (A) containing Ti and Sn and having an average primary particle diameter of 5 nm to 300 nm and / or number-based cumulative particle size distributions D10 and D90 both of which are 5 nm to 300 nm, and in which the mass ratio (content of rutile-type stannic oxide) / (content of rutile-type titanium oxide) (mass ratio), calculated as a percentage by the following method, is 0.3 to 3.5%. (Rutile-type stannic oxide content) / (Rutile-type titanium oxide content)(mass ratio)=((diffraction line intensity of rutile-type stannic oxide in a diffraction pattern obtained by powder X-ray diffractometry in the 2θ=20.0 to 80.0° range) / 9.63) / (diffraction line intensity of rutile-type titanium oxide in a diffraction pattern obtained by powder X-ray diffractometry in the 2θ=20.0 to 80.0° range) / 3.27). Here, the metal oxide (B) is, as described above, metal oxide particles (B) containing a metal oxide component different from titanium oxide. From the viewpoint of light resistance and the like, it is preferable that the mass ratio (B) / (A) is within the range of 0.05 to 0.50. The mass ratio (B) / (A) is more preferably 0.075 to 0.50, even more preferably 0.1 to 0.50, and particularly preferably 0.15 to 0.40.

[0043] In producing an aqueous sol of coated colloidal particles (B / A), it is preferable to further carry out at least one step selected from the group consisting of the following steps (b) and (c) after the above step (a). Step (b): ultrafiltering the aqueous sol of coated colloidal particles (B / A) obtained in step (a) By ultrafiltering the aqueous sol in step (b), the coated colloidal particles (B / A) can be washed or the aqueous sol can be concentrated. Having step (b) is preferable in terms of transparency, dispersibility, etc.

[0044] Step (c): A step of exchanging anions and / or cations of the aqueous sol of the coated colloidal particles (B / A) obtained in step (a). The inclusion of step (c) is preferred in terms of dispersibility, etc. The conditions for ion exchange are not particularly limited, but a preferred example is Na ＋ , K. ＋ Ions such as H ＋ It can be exchanged for ions such as

[0045] In producing an aqueous sol of coated colloidal particles (B / A), it is preferable to further carry out the following step (d) after the above step (b) or step (c). Step (d): A step of solvent-substituting an organic solvent for the aqueous solvent of the aqueous sol of coated colloidal particles (B / A) obtained in step (a), step (b), or step (c). Having step (d) is preferable in terms of the film-forming properties of the coating composition and the compatibility of the binder. Examples of the aqueous solvent substituted in step (d) include water, ethanol, methanol, n-propanol, etc., and examples of the organic solvent that substitutes it include methyl ethyl ketone, propylene glycol monomethyl ether, propylene glycol monomethyl ether acetate, etc.

[0046] The sol of the oxide colloidal particles (A) or the coated colloidal particles (B / A) can be stabilized as a sol by adding an acid and / or a basic compound as necessary. Examples of acids that can be used include inorganic acids such as hydrochloric acid and nitric acid, oxalic acid, lactic acid, tartaric acid, malic acid, citric acid, glycolic acid, hydroacrylic acid, α-oxybutyric acid, glyceric acid, and tartronic acid. Examples of basic compounds that can be used include the various amines mentioned above, as well as ammonia, alkali metal hydroxides, quaternary ammonium hydroxides such as guanidine hydroxide, tetramethylammonium hydroxide, and tetraethylammonium hydroxide, and carbonates such as ammonium carbonate and guanidine carbonate.

[0047] The sol of the oxide colloidal particles (A) or the coated colloidal particles (B / A) can be mixed with various binders, etc., as needed, to form a coating composition. Furthermore, the coating composition can be applied to a substrate to obtain a component having a high refractive index coating. Various substrates can be used, including plastic, rubber, glass, metal, ceramics, and paper. The coating composition is particularly suitable for eyeglasses, optical applications, and optical thin film applications for displays. The refractive index of the coating can be appropriately adjusted by adjusting the mixing ratio of the sol of the oxide colloidal particles (A) or the coated colloidal particles (B / A) to the binder, the type of binder, and other factors. The refractive index of the coating is preferably within the range of 1.50 to 2.40, more preferably within the range of 1.60 to 2.20, even more preferably within the range of 1.60 to 2.10, even more preferably within the range of 1.60 to 1.95, and particularly preferably within the range of 1.65 to 1.90. The high refractive index coating obtained by applying the coating composition can be further provided with an antireflection film to impart antireflection functionality.

[0048] The present invention will be described in more detail below with reference to Reference Examples, Production Examples, Examples and Comparative Examples, but the present invention is not limited to these Examples in any way.

[0049] The physical properties of the dispersion (sol) were determined by the following measurement methods.

[0050] [Total Metal Oxide Concentration] The sol was weighed in a crucible and pre-dried by heating at 110° C. for 30 minutes to remove the solvent, and then fired at 600° C. for 30 minutes. The crucible was weighed to obtain a residue, and the total metal oxide concentration was calculated from the mass of the sol.

[0051] [Average particle size by dynamic light scattering (DLS) (dynamic light scattering particle size)] The sol was diluted with a dispersion solvent to a scattering intensity of 200 to 400 cps, and the average particle size was measured using the solvent parameters with a dynamic light scattering measurement device (manufactured by Malvern Instruments Ltd., trade name: Zeta-sizer). The Z-average particle size was used as the average particle size by dynamic light scattering.

[0052] [Cumulative Particle Size Distribution by Dynamic Light Scattering (DLS) (Dynamic Light Scattering Particle Size Distribution)] Using particle size distribution analysis software (manufactured by Nikkiso Co., Ltd., product name: DMS2), the sol was diluted with a dispersion solvent so that the loading index was within a range of 0.1 to 100, and the volume-based cumulative particle size distribution (D90, D10, etc.) was measured using the solvent parameters with a dynamic light scattering measurement device (manufactured by Nikkiso Co., Ltd., product name: Nanotrac UPA-EX).

[0053] [X-ray Fluorescence (XRF) Analysis] The sol was dried on a hot plate at 110°C and pulverized using a mortar and pestle to obtain a dry powder. 0.3 g of this dry powder was spread in an analytical polyethylene container (manufactured by Rigaku Corporation, product name: Roll Sheet, Cat. No. 3399G003) tightly covered with a polypropylene film. The sample type under measurement conditions was set to powder, and the mass ratio of the metal oxide was measured using a powder X-ray fluorescence analyzer (also known as XRF, manufactured by Rigaku Corporation, product name: Supermini 200).

[0054] [XRD Measurement] (Measurement) The sol was dried on a hot plate at 110 ° C. and pulverized for 15 minutes using a mortar and pestle to obtain a dry powder. This dry powder was measured using an XRD device (manufactured by Rigaku Corporation, product name: MiniFlex600) under the following conditions to obtain a powder X-ray diffraction (XRD) pattern. Radiation source: CuKα Voltage: 40 kV Current: 15 mA Sample rotation: None Slit conditions: Variable + fixed slit system Divergence slit: 0.625 deg. Divergence vertical limiting slit: 10 mm Scattering slit: Open Receiving slit: Open Scanning mode: Continuous Scan speed: 0.1 ° / min Counting unit: Counts Step width: 0.0100 ° Operating axis: 2θ / θ Scanning range: 20,000 to 80,000 °

[0055] (Identification of XRD pattern) From the obtained XRD pattern, the diffraction peaks were identified using the ICDD (PDF-Release 2015 RDB) database. The ICDD (The International Centre for Diffraction Data) is a non-profit scientific organization that collects, edits, organizes, and distributes powder diffraction data files (PDFs) used to identify crystalline substances. It is a compilation of peak profiles obtained by X-ray diffraction of various substances.

[0056] (Calculation of Peak Area Ratio) The diffraction peaks derived from the (101) plane of rutile-type stannic oxide and the (101) plane of rutile-type titanium oxide in the XRD pattern obtained by powder X-ray diffraction were separated by approximation with a Gaussian function. In this case, the peak position derived from rutile-type stannic oxide was fixed at 2θ = 34.8° for calculation. The areas of the diffraction peaks derived from rutile-type stannic oxide and rutile-type titanium oxide after peak separation were determined, and the value expressed as a percentage (diffraction peak area derived from the (101) plane of rutile-type stannic oxide) / (diffraction peak area derived from the (101) plane of rutile-type titanium oxide) was calculated. (Calculation of Anatase Titanium Oxide / Rutile Titanium Oxide Peak Intensity Ratio) In the range of 2θ=20° to 31° in the XRD pattern, the baseline was corrected to 0, and then the ratio of (diffraction peak intensity at 2θ=25.28° derived from anatase titanium oxide / diffraction peak intensity at 2θ=27.28° derived from the (101) plane of rutile titanium oxide) was calculated.

[0057] (Calculation of (rutile-type stannic oxide content) / (rutile-type titanium oxide content) by RIR method) Using XRD patterns measured in the 2θ range of 20.0 to 80.0°, analysis was performed using integrated powder X-ray analysis software PDXL (manufactured by Rigaku Corporation) according to the reference intensity ratio (RIR) method. The RIR value of rutile-type stannic oxide was 9.63 (PDF card number 01-077-0451) and the RIR value of rutile-type titanium oxide was 3.27 (PDF card number 01-072-7374), and the ratio (rutile-type stannic oxide content) / (rutile-type titanium oxide content) was calculated according to the following formula (4): (Rutile stannic oxide content) / (Rutile titanium oxide content)=(Diffraction line intensity of rutile stannic oxide) / RIR value of stannic oxide) / (Diffraction line intensity of rutile titanium oxide) / RIR value of rutile titanium oxide)-(4) The QM (Quality Mark), which indicates the quality of the diffraction data stored on the PDF card, is as follows: S (Star Patterns): extremely good quality data; I (Indexed Patterns): indexed good quality data; O (Low-Precision): poor quality data (multiphase or unindexable); B (Blank Patterns): data other than those mentioned above; C (Calculated Patterns): data other than those mentioned above; Patterns): Calculation data, but the QM of PDF card numbers 01-072-7374 and 01-077-0451 is both determined to be S, which is a highly reliable value.

[0058] [Evaluation of Dispersion Light Fastness] A dispersion was prepared in which metal oxide particles were dispersed from the sample sol in a dispersion medium consisting of water and methanol in a mass ratio of 1:1, with a solids concentration of 0.5% by mass. This dispersion was mixed with a 0.02% by mass glycerin solution of a dye (Sunset Yellow) in a mass ratio of 1:3 to prepare a sample. This was placed in a quartz cell with a length of 1 mm, a width of 1 cm, and a height of 5 cm, and then sealed. After that, an ultraviolet lamp (manufactured by AS ONE Corporation, product name: SLUV-6) with a wavelength range of I-rays (wavelength 365 nm) selected was used to irradiate the sample with an irradiation intensity of 0.4 mW / cm. ２ The film was irradiated with ultraviolet light (wavelength: 365 nm) for 180 minutes.

[0059] On the other hand, the absorbance (A) of the sample at a wavelength of 490 nm before and after ultraviolet irradiation was ０ and A １８０ ) was measured using an ultraviolet-visible spectrophotometer (Shimadzu Corporation, product name: UV-3600), and the fading rate of the dye was calculated using the following formula (5). ０ ) indicates the absorbance at a wavelength of 490 nm before irradiation with I-rays (wavelength 365 nm), and (A １８０ ) indicates the absorbance at a wavelength of 490 nm after irradiating with I-rays (wavelength 365 nm) for 180 minutes. １８０ ) / (A ０ )) × 100 - (5) Furthermore, the photocatalytic activity of the particles was evaluated based on the following criteria. The lower the rate of fading change of particles, the more suppressed the photocatalytic activity. ◯: Rate of fading change is less than 10% ×: Rate of fading change is 10% or more

[0060] [Calculation of Primary Particle Diameter] Using images of oxide colloidal particles observed with a transmission electron microscope (manufactured by JEOL Ltd., product name: JEM-F200), the circle-equivalent diameters of 500 random particles were analyzed with an image processing analyzer (manufactured by Nireco Corporation, product name: Luzex), and the number average was taken as the average primary particle diameter. A numerical range of the primary particle diameter was calculated with the number-based cumulative particle size distribution D10 of the circle-equivalent diameters of the 500 particles as the lower limit and the number-based cumulative particle size distribution D90 as the upper limit.

[0061] Reference Example 1: Preparation of Tin Oxalate Aqueous Solution (a1) 776.3 g of pure water was placed in a 1 L container, and 22.3 g of oxalic acid dihydrate (Kanto Chemical Co., Ltd., purity 99.5% to 102.0% by mass) was dissolved therein. Next, 6.6 g of metallic tin powder (Yamaishi Metal Co., Ltd., purity >99.9% by mass, product name: No. 200) and 17.2 g of a 30% by mass aqueous hydrogen peroxide solution (Kanto Chemical Co., Ltd., purity >34.5% by mass) were added alternately in three portions, and the mixture was kept at 80 to 85°C for 2 hours to prepare SnO ２ 822.4 g of an aqueous solution of tin oxalate (a1) having a converted concentration of 1.0 mass % was prepared.

[0062] Reference Example 2: Preparation of tin oxalate aqueous solution (a2) 776.3 g of pure water was placed in a 1 L container, and 22.3 g of oxalic acid dihydrate (purity 99.5% to 102.0% by mass) was dissolved in it. Next, 6.6 g of metallic tin powder (manufactured by Yamaishi Metals Co., Ltd., purity >99.9% by mass, product name No. 200) and 17.2 g of a hydrogen peroxide aqueous solution (manufactured by Kanto Chemical Co., Inc., purity >34.5% by mass) that had been prepared in advance at 30% by mass were added alternately in three portions, and the mixture was maintained at 50 to 55°C for 30 minutes to obtain SnO ２ 822.4 g of an aqueous solution (a2) of tin oxalate with a converted concentration of 1.0 mass % was prepared.

[0063] Reference Example 3: Preparation of tin oxalate aqueous solution (a3) ​​849 g of pure water was placed in a 2 L container, and 82 g of oxalic acid dihydrate (manufactured by Ube Industries, Ltd.) was dissolved therein. Next, 22 g of metallic tin powder (manufactured by Yamaishi Metals Co., Ltd.) and 47 g of a 35% aqueous hydrogen peroxide solution (manufactured by Kanto Chemical Co., Ltd.) were added alternately in 10 portions each, and the mixture was maintained at 50 to 55°C for 2 hours. Next, the mixture was passed through a column packed with a platinum catalyst to remove excess hydrogen peroxide, and 1000 g of a tin oxalate aqueous solution (a3) ​​with a SnO2-equivalent concentration of 2.8% by mass was prepared.

[0064] (Reference Example 4): Preparation of silicon dioxide-stannic oxide composite oxide colloidal particles (B1) to be coated. ２ 77.2 g of sodium stannate (containing 29.8% by mass of sodium stannate in terms of sodium stannate equivalent) was dissolved in 668.8 g of pure water, and then sodium stannate NaSnO ３ ・H ２ O(SnO ２ An aqueous solution was obtained by dissolving 20.9 g of silicon dioxide-stannic oxide composite colloidal particles (B1) in an alkaline solution containing 20.9 g of silicon dioxide-stannic oxide composite colloidal particles (B1), which contained 55.1% by mass of silicon dioxide-stannic oxide composite colloidal particles (B1). The aqueous solution was passed through a column packed with a hydrogen cation exchange resin (Amberlite (trade name) IR-120B, manufactured by Organo Corporation) to obtain an aqueous dispersion sol. Next, 7.2 g of diisopropylamine was added to the aqueous dispersion sol. The diisopropylamine-added aqueous dispersion sol obtained was an aqueous dispersion sol of alkaline silicon dioxide-stannic oxide composite oxide colloidal particles (B1), and had a pH of 8.0, a total metal oxide concentration (main component: SiO ２ , and SnO ２When 500 randomly selected particles were observed under a transmission electron microscope, the average primary particle diameter was found to be 2 nm.

[0065] Example 1: Preparation of titanium oxide-stannic oxide composite oxide colloidal particles (A1) 158.2 g of a 35 mass % aqueous solution of tetraethylammonium hydroxide was mixed with 822.4 g of the aqueous solution of tin oxalate (a1) prepared in Reference Example 1. ２ 8.2 g in terms of the total mass of the solution), and 154.0 g of titanium tetraisopropoxide (manufactured by Kanto Chemical Co., Inc., purity >97.0 mass%) (TiO ２ To the resulting mixture, 14.0 g of oxalic acid dihydrate (Kanto Chemical Co., Ltd.) was added under stirring to obtain a mixed solution. The mixed solution was maintained at 80°C for 2 hours, and then maintained at 95°C for 5 hours while adding pure water to maintain a constant liquid level. The resulting mixture was then passed through a column packed with a platinum catalyst to remove excess hydrogen peroxide, preparing a mixed solution. The mixed solution was placed in a glass-lined autoclave and subjected to hydrothermal treatment at 140°C for 5 hours at a stirring speed of 100 rpm. After cooling to room temperature, a sol was obtained. The resulting sol was desalted and washed using pure water by ultrafiltration, and after adding 1.3 g of 35% tetraethylammonium hydroxide, the solution was passed through a column packed with 500 mL of ion exchange resin (Amberlite (trade name) IRA-410, Organo Corporation) to obtain a sol. The sol after passing the liquid was an alkaline aqueous dispersion sol of titanium oxide-stannic oxide composite oxide colloidal particles (A1), with a pH of 11.5 and a total metal oxide concentration (main component: TiO ２ , and SnO ２ The sol had a D10 content of 3.8% by mass, and observation with a transmission electron microscope revealed that the primary particle size was 5 nm (D10) to 9 nm (D90), with an average primary particle size of 8.0 nm. The resulting sol was dried at 110°C, and the powder was subjected to X-ray diffraction analysis, which confirmed that it was a rutile crystal. The evaluation results are shown in Table 1.

[0066] Example 2: Preparation of titanium oxide-stannic oxide composite oxide colloidal particles (A2) 158.2 g of a 35 mass % aqueous solution of tetraethylammonium hydroxide was mixed with 822.4 g of the aqueous solution of tin oxalate (a1) prepared in Reference Example 1. ２8.2 g equivalent), and titanium tetraisopropoxide 154.0 g (TiO ２ To the resulting mixture, 14.0 g of oxalic acid dihydrate (containing 43.3 g of hydrogen peroxide in terms of carbon dioxide equivalent) was added under stirring to obtain a mixed solution. After maintaining the mixed solution at 80°C for 2 hours, it was maintained at 95°C for 5 hours while adding pure water to maintain a constant liquid level. The resulting mixture was then passed through a column packed with a platinum catalyst to remove excess hydrogen peroxide, preparing a mixed solution. The mixed solution was placed in a glass-lined autoclave vessel and subjected to hydrothermal treatment at 150°C for 5 hours at a stirring speed of 100 rpm. After cooling to room temperature, a sol was obtained. The resulting sol was desalted and washed by ultrafiltration, and after adding 1.3 g of 35% tetraethylammonium hydroxide, the solution was passed through a column packed with 500 ml of ion exchange resin (Amberlite (trade name) IRA-410, manufactured by Organo Corporation) to obtain a sol. The sol after passing the liquid was an alkaline aqueous dispersion sol of titanium oxide-stannic oxide composite oxide colloidal particles (A2), with a pH of 11.7 and a total metal oxide concentration (main component: TiO ２ , and SnO ２ The sol had a D10 content of 2.9% by mass, and observation with a transmission electron microscope revealed that the primary particle size was 6 nm (D10) to 10 nm (D90), with an average primary particle size of 8.0 nm. The resulting sol was dried at 110°C, and the powder was subjected to X-ray diffraction analysis, which confirmed that it was a rutile crystal. The evaluation results are shown in Table 1.

[0067] Example 3: Preparation of titanium oxide-stannic oxide composite oxide colloidal particles (A3) 158.2 g of a 35 mass % aqueous solution of tetraethylammonium hydroxide was added with 822.4 g of the aqueous solution of tin oxalate (A2) prepared in Reference Example 2 (SnO ２ 8.2 g equivalent), and titanium tetraisopropoxide 154.0 g (TiO ２To the resulting mixture, 14.0 g of oxalic acid dihydrate (containing 43.3 g of hydroxybenzoates in terms of hydroxybenzoates) and 14.0 g of oxalic acid dihydrate were added under stirring to obtain a mixed solution. The mixed solution was maintained at 80°C for 2 hours, and then maintained at 95°C for 5 hours while adding pure water to maintain a constant liquid level. The mixture was then passed through a column packed with a platinum catalyst to remove excess hydrogen peroxide, thereby preparing a mixed solution. The mixed solution was placed in a glass-lined autoclave vessel and subjected to hydrothermal treatment at 140°C for 5 hours at a stirring speed of 100 rpm. After cooling to room temperature, a sol was obtained. The obtained sol was desalted and washed by ultrafiltration, and after adding 1.3 g of 35% tetraethylammonium hydroxide, the solution was passed through a column packed with 500 ml of ion exchange resin (Amberlite (trade name) IRA-410, manufactured by Organo Corporation) to obtain a sol. The sol after passing the liquid was an alkaline aqueous dispersion sol of titanium oxide-stannic oxide composite oxide colloidal particles (A3), with a pH of 11.2 and a total metal oxide concentration (main component: TiO ２ , and SnO ２ The sol had a D10 content of 3.8% by mass, and observation with a transmission electron microscope revealed that the primary particle size was 5 nm (D10) to 9 nm (D90), with an average primary particle size of 6.6 nm. The resulting sol was dried at 110°C, and the powder was subjected to X-ray diffraction analysis, which confirmed that it was a rutile crystal. The evaluation results are shown in Table 1.

[0068] Example 4 Preparation of titanium oxide-stannic oxide composite oxide colloidal particles (A4) as cores 158.2 g of a 35 mass % aqueous solution of tetraethylammonium hydroxide was mixed with 822.4 g of the aqueous solution of tin oxalate (a2) prepared in Reference Example 2 (SnO ２ 8.2 g equivalent), and titanium tetraisopropoxide 154.0 g (TiO ２To the resulting mixture, 14.0 g of oxalic acid dihydrate (containing 43.3 g of hydroxybenzoates in terms of hydroxybenzoates) was added under stirring to obtain a mixed solution. After maintaining the mixed solution at 80°C for 2 hours, it was maintained at 95°C for 5 hours while adding pure water to maintain a constant liquid level. The resulting mixture was then passed through a column packed with a platinum catalyst to remove excess hydrogen peroxide, preparing a mixed solution. The mixed solution was placed in a glass-lined autoclave vessel and subjected to hydrothermal treatment at 140°C for 12 hours at a stirring speed of 100 rpm. After cooling to room temperature, a sol was obtained. The resulting sol was desalted and washed by ultrafiltration, and after adding 1.3 g of 35% tetraethylammonium hydroxide, it was passed through a column packed with 500 ml of ion exchange resin (Amberlite (trade name) IRA-410, manufactured by Organo Corporation) to obtain a sol. The sol after passing the liquid was an alkaline aqueous dispersion sol of titanium oxide-stannic oxide composite oxide colloidal particles (A4), with a pH of 11.2 and a total metal oxide concentration (main component: TiO ２ , and SnO ２ The sol had a D10 content of 3.6% by mass, and observation with a transmission electron microscope revealed that the primary particle size was 5 nm (D10) to 9 nm (D90), with an average primary particle size of 7.0 nm. The resulting sol was dried at 110°C, and the powder was subjected to X-ray diffraction analysis, which confirmed that it was a rutile crystal. The evaluation results are shown in Table 1.

[0069] Preparation of titanium oxide-stannic oxide-zirconium oxide composite oxide colloidal particles (B / A1) modified with silicon dioxide-stannic oxide composite oxide: 25.7 g of zirconium oxychloride (ZrO ２The resulting aqueous solution (containing 5.1 g of zirconium oxychloride in terms of stannic oxide equivalent) was diluted with 288.1 g of pure water to prepare 313.8 g of an aqueous zirconium oxychloride solution, to which 719.5 g of an aqueous dispersion sol of titanium oxide-stannic oxide composite oxide colloidal particles (A4) was added under stirring. Hydrolysis was then carried out by heating at 95°C for 5 hours to obtain an aqueous dispersion sol of titanium oxide-stannic oxide-zirconium oxide composite oxide colloidal particles having a thin film layer of zirconium oxide formed on the surface. 1033.0 g of the obtained aqueous dispersion sol was added under stirring to 344.4 g of the aqueous dispersion sol of alkaline silicon dioxide-stannic oxide composite oxide colloidal particles (B1) prepared in Reference Example 4, and the mixture was passed through a column packed with 500 ml of anion exchange resin (Amberlite (trade name) IRA-410, manufactured by Organo Corporation) to obtain an aqueous dispersion sol. The water-dispersed sol after passing through was then heated at 150°C for 4 hours at a stirring speed of 100 rpm, and then passed through a column packed with a cation exchange resin (Amberlite (trade name) IR-120B, manufactured by Organo Corporation) to obtain a water-dispersed sol. 1.3 g of tri-n-pentylamine was added to the obtained water-dispersed sol, and the mixture was concentrated by an ultrafiltration membrane method to obtain a water-dispersed sol of titanium oxide-stannic oxide-zirconium oxide composite oxide colloidal particles (B / A1) modified with silicon dioxide-stannic oxide composite oxide. The aqueous dispersion sol of titanium oxide-stannic oxide-zirconium oxide composite oxide colloidal particles (B / A1) modified with silicon dioxide-stannic oxide composite oxide was evaporated in a rotary evaporator at 580 Torr and 120°C to replace the dispersion medium with methanol, thereby obtaining a methanol dispersion sol of titanium oxide-stannic oxide-zirconium oxide composite oxide colloidal particles (B / A1) modified with silicon dioxide-stannic oxide composite oxide. This methanol dispersion sol had a pH of 4.8, a total metal oxide content (main component: TiO ２ , ZrO ２ , SnO ２ , and SiO ２ The concentration of the powder was 30.5% by mass, the average particle size (Dynamic Light Scattering particle size) measured by dynamic light scattering (DLS) was 25 nm, and the primary particle size measured by observation with a transmission electron microscope was 5 nm (D10) to 10 nm (D90), with the average primary particle size being 7.1 nm. The evaluation results are shown in Table 1.

[0070] Comparative Example 1 Preparation of Titanium Oxide-Stannic Oxide Composite Oxide Colloidal Particles (A5) as Cores 328.5 g of a 35% by mass aqueous solution of tetraethylammonium hydroxide was dissolved in 84.1 g of pure water, and then 13.2 g of metastannic acid (SnO ２ 11.3 g in terms of titanium tetraisopropoxide), 213.5 g (TiO ２ To the resulting solution, 73.8 g of oxalic acid dihydrate was added under stirring to obtain a mixed solution. The mixed solution was maintained at 80°C for 2 hours, and then maintained at 95°C for 5 hours while adding pure water to maintain a constant liquid level, thereby preparing a mixed solution. The resulting mixed solution was diluted with 713.0 g of pure water, and the mixed solution was placed in a glass-lined autoclave vessel. The mixed solution was subjected to hydrothermal treatment at 140°C for 5 hours at a stirring speed of 100 rpm, and cooled to room temperature to obtain a sol. The resulting sol was desalted and washed by ultrafiltration, and after adding 1.8 g of 35% tetraethylammonium hydroxide, the solution was passed through a column packed with 500 ml of ion exchange resin (Amberlite (trade name) IRA-410, manufactured by Organo Corporation) to obtain a sol. The sol after passing through was an aqueous dispersion sol of alkaline titanium oxide-stannic oxide composite oxide colloidal particles (A5), with a pH of 11.5 and a total metal oxide concentration (TiO ２ , and SnO ２ The sol had a D10 content of 5.0% by mass, and observation with a transmission electron microscope revealed that the primary particle size was 5 nm (D10) to 9 nm (D90), with an average primary particle size of 7.0 nm. The resulting sol was dried at 110°C, and the powder was subjected to X-ray diffraction analysis, which confirmed that the sol was a rutile crystal. The evaluation results are shown in Table 1.

[0071] Preparation of titanium oxide-stannic oxide-zirconium oxide composite oxide colloidal particles (B / A2) modified with silicon dioxide-stannic oxide composite oxide: 25.7 g of zirconium oxychloride (ZrO ２The resulting aqueous solution (containing 5.1 g of zirconium oxychloride in terms of stannic oxide equivalent) was diluted with 489.6 g of pure water to prepare 515.3 g of an aqueous zirconium oxychloride solution, to which 518.0 g of an aqueous dispersion sol of titanium oxide-stannic oxide composite oxide colloidal particles (A5) was added under stirring. Hydrolysis was then carried out by heating at 95°C for 5 hours to obtain an aqueous dispersion sol of titanium oxide-stannic oxide-zirconium oxide composite oxide colloidal particles having a thin film layer of zirconium oxide formed on the surface. 1033.3 g of the obtained aqueous dispersion sol was added under stirring to 344.4 g of the aqueous dispersion sol of alkaline silicon dioxide-stannic oxide composite oxide colloidal particles (B1) prepared in Reference Example 4, and the mixture was passed through a column packed with 500 mL of anion exchange resin (Amberlite (trade name) IRA-410, manufactured by Organo Corporation) to obtain an aqueous dispersion sol. The water-dispersed sol after passing through was then heated at 150°C for 4 hours at a stirring speed of 100 rpm, and then passed through a column packed with a cation exchange resin (Amberlite (trade name) IR-120B, manufactured by Organo Corporation) to obtain a water-dispersed sol. 1.3 g of tri-n-pentylamine was added to the obtained water-dispersed sol, and the mixture was concentrated by an ultrafiltration membrane method to obtain a water-dispersed sol of titanium oxide-stannic oxide-zirconium oxide composite oxide colloidal particles (B / A2) modified with silicon dioxide-stannic oxide composite oxide. The aqueous dispersion sol of titanium oxide-stannic oxide-zirconium oxide composite oxide colloidal particles (B / A2) modified with silicon dioxide-stannic oxide composite oxide was evaporated in a rotary evaporator at 580 Torr and 120°C to replace the dispersion medium with methanol, thereby obtaining a methanol dispersion sol of titanium oxide-stannic oxide-zirconium oxide composite oxide colloidal particles (B / A2) modified with silicon dioxide-stannic oxide composite oxide. This methanol dispersion sol had a pH of 5.0, a total metal oxide (TiO ２ , ZrO ２ , SnO ２ , and SiO ２ The powder had a concentration of 30.5% by mass, a viscosity of 5.0 mPa s, an average particle size (Dynamic Light Scattering particle size) of 20 nm as determined by dynamic light scattering (DLS), and a primary particle size of 4 nm (D10) to 10 nm (D90) as determined by observation with a transmission electron microscope, with an average primary particle size of 7.2 nm. The evaluation results are shown in Table 1.

[0072] Comparative Example 2: Preparation of titanium oxide-stannic oxide composite oxide colloidal particles (A6) 44.9 g of pure water was placed in a 200 mL beaker, and 26.9 g of the tin oxalate aqueous solution (a3) ​​prepared in Reference Example 3 (containing 0.75 g in terms of SnO and 1.26 g in terms of oxalic acid), 14.2 g of titanium tetraisopropoxide (containing 4.0 g in terms of TiO), 2.2 g of oxalic acid dihydrate (containing 1.6 g in terms of oxalic acid), and 11.8 g of a 25% by mass aqueous solution of tetramethylammonium hydroxide were added with stirring. The resulting titanium-containing aqueous solution had a tin atom / titanium atom molar ratio of 0.1, an oxalic acid / titanium atom molar ratio of 0.63, and a tetramethylammonium hydroxide / titanium atom molar ratio of 0.65. 100 g of the titanium-containing aqueous solution was heated at 80°C for 2 hours and then maintained at 95°C for 5 hours to prepare a mixed solution. The mixed solution had a pH of 3.6, a conductivity of 15.5 mS / cm, and a TiO2-equivalent concentration of 4.0% by mass. 60 g of the heated titanium-containing aqueous solution was placed in a 100 mL fluororesin autoclave vessel and subjected to hydrothermal treatment at 145°C for 8 hours. After hydrothermal treatment, the vessel was cooled to room temperature. The solution after hydrothermal treatment was a pale milky white titanium oxide aqueous sol. The resulting sol had a pH of 3.4, a conductivity of 18.4 mS / cm, a TiO2-equivalent concentration of 4.0% by mass, and a particle size of 16 nm measured by dynamic light scattering. The resulting sol was desalted and washed using pure water by ultrafiltration, and after adding 0.1 g of 35% tetraethylammonium hydroxide, the sol was passed through a column packed with 50 mL of ion exchange resin (Amberlite (trade name) IRA-410, manufactured by Organo Corporation) to obtain a sol. The sol after passing the liquid was an alkaline aqueous dispersion sol of titanium oxide-stannic oxide composite oxide colloidal particles (A6), with a pH of 10.9 and a total metal oxide concentration (TiO ２ , and SnO ２ The sol had a D10 content of 5.0% by mass, and observation with a transmission electron microscope revealed that the primary particle size was 5 nm (D10) to 10 nm (D90), with an average primary particle size of 7.9 nm. The resulting sol was dried at 110°C, and the powder was subjected to X-ray diffraction analysis, which confirmed that the sol was a rutile crystal. The evaluation results are shown in Table 1.

[0073]

[0074] In each example, the use of metallic tin powder as a rutile-forming agent for titanium oxide promoted the formation of a solid solution of tin in titanium oxide, thereby suppressing the formation of stannic oxide alone. The results of XRD measurement showed that in Examples 1 to 4, in which metallic tin powder was used as a rutile-forming agent, the formation of stannic oxide alone was suppressed compared to Comparative Example 1, and among these, the rutile-type titanium oxide of Example 4 produced an extremely small amount of stannic oxide alone. In Comparative Example 2, metallic tin powder was also used as a rutile-forming agent for titanium oxide, and the formation of stannic oxide alone was suppressed as measured by the (101) plane peak area ratio. However, the early removal of hydrogen peroxide reduced the solubility of stannic oxide in the dissolution step, and therefore the suppression of the formation of stannic oxide alone was insufficient according to the RIR method. In each example, the production of stannic oxide alone was suppressed, and as a result, the amount of anatase titanium oxide as a by-product was reduced, as shown by the anatase titanium oxide / rutile titanium oxide XRD peak intensity ratio. Example 4, which used this as core particles, showed extremely good light resistance of the dispersion.

[0075] The oxide colloidal particles of the present invention, a sol containing the oxide colloidal particles, and a method for producing the oxide colloidal particles can simultaneously achieve high levels of various properties that are highly valuable in practice, such as a high refractive index, high homogeneity, high photostability, and a fine particle size, exceeding the limits of conventional technology. Therefore, the particles are useful for various applications such as optical materials, including high refractive index sols for eyeglasses and optical applications, and are highly applicable in various fields of industries such as optical equipment, medical equipment, electrical and electronic equipment, communications, and medicine.

Claims

1. Oxide colloidal particles (A) containing Ti and Sn, having an average primary particle diameter of 5 nm to 300 nm and / or a primary particle diameter in which the cumulative particle size distributions D10 and D90 based on number are both 5 nm to 300 nm, wherein the percentage of (rutile-type stannic oxide content) / (rutile-type titanium oxide content) (mass ratio), calculated by the following method, is 0.3 to 3.5%: (rutile-type stannic oxide content) / (rutile-type titanium oxide content) (mass ratio)=((diffraction line intensity of rutile-type stannic oxide in a diffraction pattern obtained by powder X-ray diffraction measurement in the 2θ = 20.0 to 80.0° range) / 9.63) / (diffraction line intensity of rutile-type titanium oxide in a diffraction pattern obtained by powder X-ray diffraction measurement in the 2θ = 20.0 to 80.0° range) / 3.

27.

2. The oxide colloidal particles (A) according to claim 1, wherein the value calculated from the diffraction pattern obtained by powder X-ray diffraction method, (the area of the diffraction peak derived from the (101) plane of rutile-type stannic oxide) / (the area of the diffraction peak derived from the (101) plane of rutile-type titanium oxide), expressed as a percentage, is 1.0 to 40%.

3. The oxide colloid particles (A) according to claim 1, wherein the volume-based cumulative particle size distribution D90 - cumulative particle size distribution D10 of the oxide colloid particles (A) measured by a dynamic light scattering method is 5 to 30 (nm), and the standard deviation of the average particle diameter is 1.5 to 10 (nm).

4. Coated colloidal particles (B / A) in which the surface of the oxide colloidal particles (A) according to claim 1 is coated with a metal oxide (B) containing a metal oxide component different from titanium oxide.

5. The coated colloidal particles (B / A) according to claim 4, wherein the metal oxide (B) contains at least one selected from the group consisting of silicon dioxide, tin oxide, antimony oxide, tungsten oxide, aluminum oxide, and zirconium oxide.

6. The coated colloidal particles (B / A) according to claim 4, wherein the metal oxide (B) contains a silicon dioxide-stannic oxide composite oxide having a silicon dioxide / stannic oxide mass ratio of 0.1 to 5.0, and has the form of colloidal particles having an average primary particle size of 1 to 20 nm.

7. Coated colloidal particles (B / A) according to claim 4, wherein the ratio of (mass of metal oxide (B)) / (mass of oxide colloidal particles (A)) is 0.05 to 0.

50.

8. The oxide colloid particles (A) according to claim 1, wherein the refractive index of the oxide colloid particles (A) is 2.0 to 2.

6.

9. Coated colloid particles (B / A) according to claim 4, comprising: forming an aqueous colloidal solution containing the coated colloidal particles (B / A), 6-hydroxy-5-[(4-sulfophenyl)azo]-2-naphthalenesulfonate disodium dye (E), water, methanol, and glycerin in amounts such that the mass ratio of coated colloidal particles (B / A): dye (E): water: methanol: glycerin is 1:0.12:99.5:99.5:599.88; and irradiating the aqueous colloidal solution with light of 365 nm wavelength at 0.4 mW / cm. ２ 5. The coated colloidal particles (B / A) according to claim 4, wherein the change in absorbance of the aqueous colloidal solution at a wavelength of 490 nm after irradiation for 180 minutes is less than 10%.

10. The oxide colloid particles (A) according to claim 1, further comprising a particle surface coated with an amine.

11. Oxide colloid particles (A) according to claim 1, wherein the oxide colloid particles (A) containing Ti and Sn are oxide colloid particles produced by a sol-gel method using titanium alkoxide as the titanium-containing compound.

12. The oxide colloidal particles (A) have a surface coated with a hydrolyzable silane (1) having the structure shown in the following formula (ii): (In formula (ii), R １ represents an organic group having an alkyl group, an aryl group, a halogenated alkyl group, a halogenated aryl group, an alkenyl group, a polyether group, an epoxy group, an acryloyl group, a methacryloyl group, a mercapto group, a ureido group, an amino group, or a cyano group, and which is bonded to a silicon atom via a Si-C bond; R ２ represents an alkoxy group, an acyloxy group, or a halogen group, and a represents an integer of 1 to 3.

13. A sol of oxide colloid particles (A) and / or coated colloid particles (B / A) in which the oxide colloid particles (A) according to any one of claims 1 to 3, 8, and 10 to 12 and / or the coated colloid particles (B / A) according to any one of claims 4 to 7, and 9 are dispersed as dispersoids in a liquid medium, wherein the sol has an average particle size of 5 to 500 nm as measured by a dynamic light scattering method.

14. The sol according to claim 13, wherein the liquid medium is an organic solvent.

15. The sol according to claim 13 or 14, further comprising an amine.

16. A method for producing an aqueous sol of coated colloidal particles (B / A), comprising the following step (a): Step (a): mixing an aqueous sol containing the oxide colloidal particles (A) according to claim 1 with an aqueous sol containing a metal oxide (B) containing a metal oxide component other than titanium oxide in a mass ratio (B) / (A) of 0.05 to 0.50 to obtain an aqueous sol of coated colloidal particles (B / A) in which the metal oxide (B) is coated on the oxide colloidal particles (A).

17. A method for producing an aqueous sol of coated colloid particles (B / A) according to claim 16, further comprising, after step (a), at least one step selected from the group consisting of the following steps (b) and (c): step (b): ultrafiltrating the aqueous sol of coated colloid particles (B / A) obtained in step (a); step (c): cation-exchanging and / or anion-exchanging the aqueous sol of coated colloid particles (B / A) obtained in step (a).

18. A method for producing an organic solvent sol of coated colloidal particles (B / A), comprising the following step (d) after step (a) as set forth in claim 16: step (d): a step of solvent-substituting an organic solvent for the aqueous solvent of the aqueous sol of coated colloidal particles (B / A) obtained in step (a).

19. A method for producing an organic solvent sol of coated colloidal particles (B / A), comprising the following step (d') after step (b) or step (c) according to claim 17: Step (d'): A step of solvent-substituting an organic solvent for the aqueous solvent of the aqueous sol of coated colloidal particles (B / A) obtained in step (b) or step (c).

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