Dispersion of titanium dioxide fine particles in organic solvent, method for producing same, and use of same

Abstract

The present invention addresses the problem of providing: a dispersion of titanium dioxide fine particles in an organic solvent, the dispersion having high dispersion stability; and a method for producing the same.　The present invention provides a dispersion of titanium dioxide fine particles in an organic solvent, the dispersion containing: titanium dioxide fine particles in each of which a titanium component, a tin component, and an aluminum component are detected by X-ray fluorescence analysis measurement, and an X-ray diffraction peak derived from rutile titanium dioxide is observed but X-ray diffraction peaks derived from the tin component and the aluminum component are not observed by powder X-ray diffraction measurement; an organic solvent; a silane coupling agent; and a dispersant that has a basic adsorption group.

Description

Organic solvent dispersion of titanium dioxide fine particles, its production method and use

[0001] The present invention relates to an organic solvent dispersion of titanium dioxide fine particles, a method for producing the same, and uses thereof.

[0002] Titanium dioxide fine particles are a material that has excellent properties such as visible light transmittance (i.e., transparency), ultraviolet shielding properties, a high refractive index, etc. To utilize these properties, it is usually necessary to disperse titanium dioxide fine particles in an organic solvent to prepare an organic solvent dispersion or a coating composition, which is then applied or sprayed onto a substrate to form a coating film containing the titanium dioxide fine particles.

[0003] Organic solvent dispersions of titanium dioxide fine particles are used, for example, to form hard coats or ultraviolet-shielding coatings having high visible light transmittance (i.e., transparency) and a high refractive index on the surfaces of substrates such as synthetic resin lenses and films. Additionally, the display surfaces of flat panel displays such as liquid crystal displays, plasma displays, and electroluminescent displays are provided with antireflection films that combine a high refractive index layer and a low refractive index layer for the purpose of preventing reflections of light sources or faces, and organic solvent dispersions of titanium dioxide fine particles are also used for these high refractive index layers.

[0004] However, organic solvent dispersions of titanium dioxide fine particles have the problem that the titanium dioxide fine particles tend to aggregate in the organic solvent dispersion. Organic solvent dispersions containing aggregated titanium dioxide fine particles have low transparency, and therefore coating films produced using such dispersions also have low transparency. Furthermore, organic solvent dispersions containing aggregated titanium dioxide fine particles experience settling of the titanium dioxide fine particles during the production process, resulting in a low yield of organic solvent dispersion usable for coating films.

[0005] For the above reasons, methods for obtaining organic solvent dispersions of titanium dioxide fine particles with excellent dispersion stability have been investigated.

[0006] For example, Patent Document 1 describes an organic solvent dispersion of titanium dioxide fine particles, which contains titanium dioxide fine particles, an organic solvent, a silane coupling agent, and a dispersant having a basic adsorptive group, and the mass ratio of the dispersant to the silane coupling agent is 15 mass % to 75 mass %. Furthermore, Example 2 of Patent Document 1 describes a dispersion of titanium dioxide fine particles in an organic solvent, which contains titanium dioxide fine particles, an organic solvent, a silane coupling agent, and a dispersant having a basic adsorptive group, and the mass ratio of the dispersant to the silane coupling agent is 15 mass % to 75 mass %. ２ / TiO ２ The tin-containing rutile-type titanium oxide is obtained by thermal hydrolysis. ２ O ３ The aluminum hydroxide surface-treated rutile-type titanium dioxide slurry, in which aluminum hydroxide had been precipitated so that the titanium dioxide concentration was 15% by mass in terms of the total mass of the titanium dioxide particles, was dried at 150°C, and the resulting uncalcined titanium dioxide fine particles were wet-dispersed with a silane coupling agent, a dispersant, and an organic solvent, and the resulting dispersion was centrifuged at 2400 G for 13 minutes, and the supernatant was recovered to obtain an organic solvent dispersion of titanium dioxide fine particles. ０ and a core-shell type tetragonal titanium oxide solid solution organic solvent dispersion in which a core-shell type tetragonal titanium oxide solid solution having tetragonal titanium oxide fine particles having one or more of the above-mentioned (a) and (b) dissolved therein as a solid solution and a silicon oxide shell around the nucleus is dispersed in an organic solvent. Example 6 also describes a method for preparing a titanium oxide dispersion by adding tin(IV) chloride pentahydrate and aluminum(III) chloride to an aqueous titanium(IV) chloride solution, neutralizing the solution with aqueous ammonia, and hydrolyzing the solution to obtain a precipitate of titanium hydroxide containing tin and aluminum, adding 30% by mass of hydrogen peroxide to obtain a translucent tin-containing peroxotitanic acid solution, and subjecting the solution to hydrothermal treatment in an autoclave at 200°C and 1.5 MPa for 120 minutes.

[0007] International Publication No. 2021 / 106747 Japanese Patent Application Laid-Open No. 2015-221742

[0008] However, the organic solvent dispersions of titanium dioxide fine particles described in Patent Documents 1 and 2 both have insufficient dispersion stability, and there is a demand for organic solvent dispersions of titanium dioxide fine particles having higher dispersion stability.

[0009] The present inventors have conducted extensive research to improve the dispersion stability of organic solvent dispersions containing titanium dioxide microparticles. As a result, they have found that it is effective to use titanium dioxide microparticles in which tin and aluminum components are detected and in which X-ray diffraction peaks attributable to rutile titanium dioxide (or only X-ray diffraction peaks attributable to rutile titanium dioxide) are observed by powder X-ray diffraction measurement, but in which X-ray diffraction peaks attributable to tin and aluminum components are not observed, and that an organic solvent dispersion containing the titanium dioxide microparticles, a silane coupling agent, a dispersant having a basic adsorptive group, and an organic solvent can have higher dispersion stability, thereby completing the present invention.

[0010] That is, the present invention provides: (1) an organic solvent dispersion of titanium dioxide fine particles, comprising: titanium dioxide fine particles in which titanium components, tin components, and aluminum components are detected by X-ray fluorescence analysis, and in which X-ray diffraction peaks attributable to rutile titanium dioxide are observed by X-ray powder diffraction analysis, but X-ray diffraction peaks attributable to tin components and aluminum components are not observed; an organic solvent, a silane coupling agent, and a dispersant having a basic adsorptive group; (2) an organic solvent dispersion of titanium dioxide fine particles, comprising: titanium dioxide fine particles in which titanium components, tin components, and aluminum components are detected by X-ray fluorescence analysis, and in which X-ray diffraction peaks attributable to rutile titanium dioxide are observed by X-ray powder diffraction analysis, but X-ray diffraction peaks attributable to tin components and aluminum components are not observed; an organic solvent, a silane coupling agent, and a dispersant having a basic adsorptive group; (3) (4) The organic solvent dispersion of titanium dioxide fine particles according to (1) or (2), wherein the titanium dioxide fine particles contain titanium dioxide fine particles in which a tin component and an aluminum component are solid-dissolved. (5) The organic solvent dispersion of titanium dioxide fine particles according to (1) or (2), wherein the total amount of the tin component and the aluminum component relative to the amount of the titanium component in the titanium dioxide fine particles is such that the amount of the titanium component is TiO ２amount 、 The amount of the tin component is SnO ２ and the amount of the aluminum component is Al ２ O ３ Converted to the amount [(SnO ２ Amount + Al ２ O ３ amount) / TiO ２ (5) The organic solvent dispersion of titanium dioxide fine particles according to any one of (1) to (3), wherein the amount of the tin component relative to the amount of the aluminum component is 0.6 mass % or more and 30 mass % or less when expressed in terms of a mass ratio of the aluminum component to the tin component; ２ O ３ and the amount of the tin component is SnO ２ Converted to the amount [SnO ２ Amount / Al ２ O ３(6) An organic solvent dispersion of titanium dioxide fine particles according to any one of (1) to (4), wherein the mass ratio of the dispersant having a basic adsorptive group to the silane coupling agent is 15 mass% to 75 mass%. (7) An organic solvent dispersion of titanium dioxide fine particles according to any one of (1) to (6), wherein the mass ratio of the dispersant having a basic adsorptive group to the silane coupling agent is 15 mass% to 75 mass%. (8) An organic solvent dispersion of titanium dioxide fine particles according to any one of (1) to (6), wherein the titanium dioxide fine particles further contain one or more components selected from the group consisting of silicon components, cobalt components, and manganese components, as detected by fluorescent X-ray analysis, and wherein no X-ray diffraction peaks derived from one or more components selected from the group consisting of silicon components, cobalt components, and manganese components are observed by powder X-ray diffraction analysis. (9) An organic solvent dispersion of titanium dioxide fine particles according to any one of (1) to (7), wherein the titanium dioxide fine particles contain titanium dioxide fine particles having one or more components selected from the group consisting of a silicon component, a cobalt component, and a manganese component dissolved therein as a solid solution; (10) An organic solvent dispersion of titanium dioxide fine particles according to any one of (1) to (8), wherein the surfaces of the titanium dioxide fine particles are coated with an inorganic compound; (11) A coating composition comprising the organic solvent dispersion of titanium dioxide fine particles according to any one of (1) to (9) and a binder resin; (12) A composition for nanoimprints comprising the organic solvent dispersion of titanium dioxide fine particles according to any one of (1) to (9) and a binder resin; (13) a method for producing an organic solvent dispersion of titanium dioxide fine particles, the method comprising the step of dispersing titanium dioxide fine particles in an organic solvent, in which titanium components, tin components, and aluminum components are detected by X-ray fluorescence analysis, and in which X-ray diffraction peaks attributable to rutile titanium dioxide are observed by X-ray powder diffraction measurement, but X-ray diffraction peaks attributable to tin components and aluminum components are not observed, a silane coupling agent, and a dispersant having a basic adsorptive group;(14) A method for producing an organic solvent dispersion of titanium dioxide fine particles, comprising the step of dispersing titanium dioxide fine particles in an organic solvent, in which titanium components, tin components, and aluminum components are detected by X-ray fluorescence analysis and in which only X-ray diffraction peaks derived from rutile titanium dioxide, but no X-ray diffraction peaks derived from tin components and aluminum components, are observed by powder X-ray diffraction analysis, a silane coupling agent, and a dispersant having a basic adsorptive group; (15) A method for producing an organic solvent dispersion of titanium dioxide fine particles according to (13) or (14), comprising the step of further centrifuging the organic solvent dispersion; (16) A method for producing an organic solvent dispersion of titanium dioxide fine particles according to any one of (13) to (15), in which the titanium dioxide fine particles are produced by the following steps: Step (1): hydrolyzing a mixture of titanium (oxy)chloride and a tin compound, or hydrolyzing titanium (oxy)chloride in the presence of core particles obtained by hydrolyzing a tin compound; Step (2): mixing the product after the hydrolysis with an aluminum compound; and Step (3): A step comprising calcining a mixture of the product after the hydrolysis and an aluminum compound at a temperature of 250°C or higher and 1000°C or lower. (17) The method for producing an organic solvent dispersion of titanium dioxide fine particles according to (16), wherein step (1) is a step of hydrolyzing a mixture of titanium (oxy)chloride, a tin compound, and a carboxylic acid or a salt thereof, or a step of adding titanium (oxy)chloride and a carboxylic acid or a salt thereof in the presence of core particles obtained by hydrolyzing a tin compound to hydrolyze the titanium (oxy)chloride.

[0011] According to the present invention, an organic solvent dispersion containing titanium dioxide fine particles having high dispersion stability can be obtained.

[0012] 1 is an X-ray diffraction spectrum of titanium dioxide fine particles of Production Example 2.

[0013] The present invention provides an organic solvent dispersion of titanium dioxide microparticles, comprising titanium dioxide microparticles in which titanium components, tin components, and aluminum components are detected by X-ray fluorescence analysis and in which X-ray diffraction peaks attributable to rutile titanium dioxide are observed by powder X-ray diffraction measurement, but X-ray diffraction peaks attributable to tin components and aluminum components are not observed; an organic solvent; a silane coupling agent; and a dispersant having a basic adsorptive group.

[0014] The present invention provides an organic solvent dispersion of titanium dioxide microparticles, comprising titanium dioxide microparticles in which titanium components, tin components, and aluminum components are detected by X-ray fluorescence analysis, and in which only X-ray diffraction peaks attributable to rutile titanium dioxide are observed by powder X-ray diffraction measurement, but no X-ray diffraction peaks attributable to tin components and aluminum components are observed; an organic solvent; a silane coupling agent; and a dispersant having a basic adsorptive group.

[0015] The organic solvent dispersion of the present invention has excellent dispersion stability. Dispersion stability can be evaluated from the yield (also referred to as dispersion yield) and transparency of the organic solvent dispersion. The yield of the organic solvent dispersion is calculated by dividing the concentration of titanium dioxide fine particles remaining in the supernatant obtained when the organic solvent dispersion containing the titanium dioxide fine particles is centrifuged at 2400 G for 30 minutes by the concentration of titanium dioxide fine particles contained in the organic solvent dispersion before centrifugation.

[0016] A dispersion yield of 50% or more is considered to be an excellent yield, and a dispersion yield of 70% or more is more preferable, and a dispersion yield of 80% or more is even more preferable.

[0017] The transparency is evaluated by the average spectral transmittance of the organic solvent dispersion in the visible light range of 380 nm to 780 nm. The average spectral transmittance is measured as follows. As a measurement sample, an organic solvent dispersion having a titanium dioxide fine particle concentration of 12 g / L is prepared. The prepared measurement sample is placed in a 10 mm quartz cell, and the average spectral transmittance in the wavelength range of 380 nm to 780 nm is measured. As a spectrophotometer, for example, an ultraviolet-visible-near-infrared spectrophotometer (V-770, manufactured by JASCO Corporation) can be used.

[0018] If the average spectral transmittance is 25% or more, it can be determined that the transparency is excellent. Furthermore, the average spectral transmittance is more preferably 28% or more, and even more preferably 30% or more.

[0019] The organic solvent dispersion of the present invention can be judged to have excellent dispersion stability if the dispersion yield is 50% or more and the average spectral transmittance is 25% or more, more preferably if the yield is 70% or more and the average spectral transmittance is 28% or more, and even more preferably if the yield is 80% or more and the average spectral transmittance is 30% or more.

[0020] The dispersed particle diameter in the organic solvent dispersion of the present invention is preferably 10 nm or more and 50 nm or less, more preferably 10 nm or more and 40 nm or less, in terms of cumulative 50% diameter (D50) on a volume basis. Furthermore, the dispersed particle diameter in the organic solvent dispersion of the present invention is preferably 30 nm or more and 70 nm or less, more preferably 30 nm or more and 60 nm or less, in terms of cumulative 90% diameter (D90) on a volume basis. Dispersed particle diameters within the above ranges can provide an organic solvent dispersion with high transparency.

[0021] The dispersed particle size in the organic solvent dispersion can be measured using a dynamic light scattering particle size distribution analyzer (NANOTRAC (registered trademark) WAVE II EX150, manufactured by Microtrackbell Co., Ltd.) or the like, and the refractive index and viscosity of the solvent are set to the following values ​​depending on the solvent used. Note that the measurement conditions when the organic solvent in the organic solvent dispersion is propylene glycol monomethyl ether are as follows. Measurement conditions: (1) Refractive index of solvent (propylene glycol monomethyl ether, hereinafter also referred to as PGME): 1.4, viscosity: 1.75 (25°C) - 1.55 (30°C); (2) Particle refractive index: 2.55; (3) Particle density: 4.2 g / cm ３ and (4) loading index: 0.1 to 0.3.

[0022] The dispersed particle size in the organic solvent dispersion can be measured using a dynamic light scattering particle size distribution analyzer (NANOTRAC (registered trademark) WAVE II EX150, manufactured by Microtrackbell Co., Ltd.). The measurement conditions when the organic solvent in the organic solvent dispersion is propylene glycol monomethyl ether acetate are as follows. Measurement conditions: (1) Refractive index of solvent (propylene glycol monomethyl ether acetate, hereinafter also referred to as PGMEA): 1.4, viscosity: 1.098 (20°C) - 0.948 (30°C); (2) Particle refractive index: 2.55; (3) Particle density: 4.2 g / cm ３ and (4) loading index: 0.1 to 0.3.

[0023] Furthermore, with regard to the dispersed particle diameter in the organic solvent dispersion of the present invention, the ratio of D50 to D90 (D50 / D90) is preferably 0.3 or more and 1.0 or less, more preferably 0.5 or more and 1.0 or less. Thus, the lower limit is preferably 0.3 or more and more preferably 0.5 or more. The upper limit is preferably 1.0 or less and more preferably less than 1.0. D50 / D90 indicates the proportion of coarse particles contained in the organic solvent dispersion, and the closer this value is to 1, the fewer coarse particles there are. Fewer coarse particles results in better dispersion stability, so D50 / D90 is preferably within the above range.

[0024] The organic solvent dispersion of the present invention contains titanium dioxide microparticles in which titanium components, tin components, and aluminum components are detected by X-ray fluorescence analysis, and X-ray diffraction peaks derived from rutile titanium dioxide are observed by powder X-ray diffraction measurement, but X-ray diffraction peaks derived from tin components and aluminum components are not observed.

[0025] The organic solvent dispersion of the present invention contains titanium dioxide fine particles in which titanium components, tin components, and aluminum components are detected by X-ray fluorescence analysis, and in which only X-ray diffraction peaks derived from rutile titanium dioxide are observed by powder X-ray diffraction measurement, but no X-ray diffraction peaks derived from tin components or aluminum components are observed.

[0026] The use of such titanium dioxide fine particles can improve the dispersion stability of the titanium dioxide fine particles in the organic solvent dispersion, and can also prevent gelation during the preparation of the organic solvent dispersion.

[0027] In the present application, "no X-ray diffraction peak is observed" is defined as an X-ray diffraction peak having an intensity of 1 / 100 or less of the intensity obtained by subtracting the baseline from the (110) plane (approximately 27.5°), which is the main peak of rutile-type titanium dioxide microparticles.

[0028] The X-ray diffraction peaks derived from the rutile titanium dioxide are identified from at least three or more diffraction peaks with the highest intensity, with reference to values ​​described in a literature (RSC Adv., 2020, 10, 43592-43598.). Furthermore, an X-ray diffractometer (Ultima IV, manufactured by Rigaku Corporation), for example, can be used as an apparatus for obtaining the X-ray diffraction peaks. From the viewpoint of measurement accuracy, peaks that appear within a range of ±0.5° from each peak are considered to be within the measurement error range, and preferably within a range of ±0.2°.

[0029] In the titanium dioxide fine particles used in the present invention, the X-ray fluorescence analyzer used to detect the titanium component, tin component, and aluminum component may be, for example, ZSX Primus IV manufactured by Rigaku Corporation.

[0030] The amount of components detected by X-ray fluorescence analysis is the total amount present in the titanium dioxide microparticles, and is the sum of, for example, the amount of components dissolved in the titanium dioxide microparticles and the amount of components present on the surface of the titanium dioxide microparticles.

[0031] The proportion of tin in the titanium dioxide fine particles used in the present invention is determined by adjusting the amount of the tin in the titanium dioxide fine particles to SnO ２ The amount of titanium contained in the titanium dioxide fine particles is converted into the amount of titanium (specifically, the amount of titanium dioxide (TiO ２ The mass ratio of oxide (SnO ２ Amount / TiO ２ When expressed in terms of the amount of the hydroxybenzoate, the content is preferably 0.1% by mass or more and 20% by mass or less, and more preferably 2% by mass or more and 7% by mass or less.

[0032] The proportion of the aluminum component in the titanium dioxide fine particles used in the present invention is determined by adjusting the amount of the aluminum component to Al ２ O ３ The amount of titanium contained in the titanium dioxide fine particles is converted into the amount of titanium (specifically, the amount of titanium dioxide (TiO ２ The mass ratio of oxide equivalent (Al ２ O ３ Amount / TiO ２ When expressed in terms of the amount of the hydroxybenzoate, the amount is preferably 0.5% by mass or more and 10% by mass or less, and more preferably 2% by mass or more and 8% by mass or less.

[0033] The ratio of the total amount of the tin component and the aluminum component in the titanium dioxide fine particles used in the present invention is as follows: ２ The amount of the aluminum component is ２ O ３ The amount of titanium dioxide contained in the titanium dioxide fine particles (TiO ２ The mass ratio of oxide equivalent (SnO ２ Amount + Al２ O ３ amount) / TiO ２ When expressed in terms of the amount of the hydroxybenzoate, the hydroxybenzoate content is preferably 0.6% by mass or more and 30% by mass or less, and more preferably 4% by mass or more and 15% by mass or less.

[0034] The ratio of the tin component to the aluminum component in the titanium dioxide fine particles used in the present invention is determined by the following formula: ２ O ３ and the amount of the tin component is SnO ２ The mass ratio of SnO ２ Amount / Al ２ O ３ When expressed in terms of the amount of hydroxybenzoates, the content is preferably 0.01% by mass or more and 40% by mass or less, and more preferably 0.1% by mass or more and 4.0% by mass or less.

[0035] When the titanium dioxide microparticles used in the present invention are subjected to X-ray fluorescence analysis, one or more third components may be detected in addition to the titanium component, tin component, and aluminum component. Detecting the third component makes it possible to improve light resistance (i.e., suppress photocatalytic activity) and control particle shape during firing. Specific examples of the third component include silicon component, zirconium component, zinc component, cobalt component, niobium component, manganese component, etc. Among these, silicon component, cobalt component, and manganese component are particularly preferred. Specific compounds include SiO ２ , ZrO ２ , ZnO, CoO, Nb ２ O ５ , Co ２ O ３ , MnO, etc., and SiO ２ , Co ２ O ３ , MnO is preferred.

[0036] The content of these third components is determined based on the amount of titanium dioxide (TiO ２ The amount of tin contained in the titanium dioxide fine particles is calculated based on the amount of SnO ２ The amount of aluminum component is Al ２ O ３The amount of the third component is converted to the amount of oxide of the third component, and the mass ratio ((SnO ２ Amount + Al ２ O ３ Amount of the oxide of the third component + amount of the oxide of the third component) / TiO ２ When expressed in terms of the amount of the hydroxybenzoate, the hydroxybenzoate content is preferably 0.6% by mass or more and 30% by mass or less, and more preferably 4% by mass or more and 15% by mass or less.

[0037] When the third component is a silicon component, the amount of the component is SiO ２ Calculated as the amount of SiO ２ The content of titanium dioxide is the amount of titanium dioxide contained in the titanium dioxide fine particles (TiO ２ The mass ratio of oxide equivalent (SiO ２ Amount / TiO ２ When expressed in terms of the amount of the hydroxybenzoates, the amount is preferably 0.5% by mass or more and 10% by mass or less, and more preferably 1% by mass or more and 5% by mass or less.

[0038] When the third component is a cobalt component, the amount of the component is Co ２ O ３ Calculated as the amount of Co ２ O ３ The content of titanium dioxide is the amount of titanium dioxide contained in the titanium dioxide fine particles (TiO ２ The mass ratio of oxide equivalent (Co ２ O ３ Amount / TiO ２ When expressed in terms of the amount of hydroxybenzoates, the content is preferably 0.05% by mass or more and 5% by mass or less, and more preferably 0.07% by mass or more and 3% by mass or less.

[0039] When the third component is manganese element, the amount of this component is calculated as the amount of MnO, and the content of MnO is calculated based on the amount of titanium dioxide (TiO ２ The mass ratio of oxides (MnO amount / TiO ２ When expressed in terms of the amount of hydroxybenzoates, the content is preferably 0.05% by mass or more and 5% by mass or less, and more preferably 0.07% by mass or more and 3% by mass or less.

[0040] The organic solvent dispersion of the present invention preferably contains titanium dioxide fine particles in which a tin component and an aluminum component are solid-dissolved. That is, the titanium dioxide fine particles constituting the organic solvent dispersion of the present invention, in which a titanium component, a tin component, and an aluminum component are detected by X-ray fluorescence analysis, and in which X-ray diffraction peaks attributable to rutile titanium dioxide are observed by powder X-ray diffraction measurement, but X-ray diffraction peaks attributable to the tin component and the aluminum component are not observed, preferably contain titanium dioxide fine particles in which a tin component and an aluminum component are solid-dissolved. This means that all of the titanium dioxide fine particles in which a titanium component, a tin component, and an aluminum component are detected by X-ray fluorescence analysis, and in which X-ray diffraction peaks attributable to rutile titanium dioxide are observed by powder X-ray diffraction measurement, but X-ray diffraction peaks attributable to the tin component and the aluminum component are not observed, may be titanium dioxide fine particles in which a tin component and an aluminum component are solid-dissolved, or only a portion of the fine particles may be titanium dioxide fine particles in which a tin component and an aluminum component are solid-dissolved. In titanium dioxide microparticles in which titanium components, tin components, and aluminum components are detected by X-ray fluorescence analysis, and X-ray diffraction peaks attributable to rutile titanium dioxide are observed by powder X-ray diffraction measurement, but X-ray diffraction peaks attributable to tin components and aluminum components are not observed, it is preferable that the proportion of titanium dioxide microparticles in which the tin components and the aluminum components are solid-dissolved is high, and it is particularly preferable that all of the microparticles are titanium dioxide microparticles in which the tin components and the aluminum components are solid-dissolved.

[0041] In this application, the term "solid solution" refers to a phase in which atoms at the lattice points of a certain crystal phase are replaced with other atoms, or other atoms enter the lattice gaps, i.e., a mixed phase in which another substance is considered to have dissolved into a certain crystal phase, and the crystalline phase is a homogeneous phase. A state in which solvent atoms at the lattice points are replaced with solute atoms is called a substitutional type, and a state in which solute atoms enter the lattice gaps is called an interstitial type. In this specification, "solid solution" refers to either of these states.

[0042] Specifically, when the solid solution state is substitutional, titanium sites in the crystal lattice of the titanium dioxide fine particles are substituted with tin atoms or aluminum atoms, and when the solid solution state is interstitial, tin atoms or aluminum atoms enter the lattice gaps in the crystals of the titanium dioxide fine particles.

[0043] The fact that the tin component and the aluminum component are solid-dissolved in the titanium dioxide fine particles can be confirmed by a shift in the peak attributable to titanium dioxide in X-ray diffraction.

[0044] The use of titanium dioxide microparticles in which a tin component and an aluminum component are dissolved can improve the dispersion stability of the organic solvent dispersion compared to the use of titanium dioxide microparticles in which these components are not dissolved.

[0045] This is presumably because dissolving the above components in titanium dioxide microparticles reduces the amount of coarse particles and particles with a large aspect ratio, which results in a more uniform particle size distribution and particle shape, improving the dispersion stability of the titanium dioxide microparticles in the organic solvent dispersion.

[0046] The titanium dioxide microparticles used in the present invention may contain one or more solid-solution third components in addition to the tin component and aluminum component. The presence of the solid-solution third component improves light resistance (i.e., suppresses photocatalytic activity) and enables control of particle shape during firing. Specific examples of the solid-solution third component include silicon component (Si), zirconium component (Zr), zinc component (Zn), cobalt component (Co), niobium component (Nb), and manganese component (Mn). Among these, silicon component, cobalt component, and manganese component are particularly preferred.

[0047] The organic solvent dispersion of the present invention may contain, as titanium dioxide microparticles in which titanium components, tin components, and aluminum components are detected by X-ray fluorescence analysis, and X-ray diffraction peaks derived from rutile titanium dioxide are observed by powder X-ray diffraction measurement, but X-ray diffraction peaks derived from tin components and aluminum components are not observed, a calcined product of titanium dioxide microparticles obtained by calcining titanium dioxide microparticles having a tin component dissolved therein with an aluminum compound.

[0048] The organic solvent dispersion of the present invention may contain, as titanium dioxide microparticles in which titanium components, tin components, and aluminum components are detected by X-ray fluorescence analysis, and in which only X-ray diffraction peaks derived from rutile titanium dioxide are observed by powder X-ray diffraction measurement, but no X-ray diffraction peaks derived from tin components and aluminum components are observed, a calcined product of titanium dioxide microparticles obtained by calcining titanium dioxide microparticles having a tin component dissolved therein with an aluminum compound.

[0049] By using titanium dioxide microparticles that are a calcined product obtained by calcining titanium dioxide microparticles containing a tin component dissolved therein with an aluminum compound as titanium dioxide microparticles in which titanium components, tin components, and aluminum components are detected by X-ray fluorescence analysis, and in which X-ray diffraction peaks attributable to rutile titanium dioxide (or only X-ray diffraction peaks attributable to rutile titanium dioxide) are observed by powder X-ray diffraction measurement, but in which X-ray diffraction peaks attributable to tin components and aluminum components are not observed, the dispersion stability of titanium dioxide microparticles in an organic solvent dispersion can be improved.

[0050] The organic solvent dispersion of the present invention may also contain, as the titanium dioxide fine particles used in the organic solvent dispersion, a calcined product of titanium dioxide fine particles obtained by calcining titanium dioxide fine particles having a tin component dissolved therein, an aluminum compound, and one or more compounds selected from the group consisting of silicon compounds, cobalt compounds, and manganese compounds.

[0051] By using titanium dioxide microparticles that are a calcined product of titanium dioxide microparticles containing the tin component as a solid solution, an aluminum compound, and one or more compounds selected from the group consisting of silicon compounds, cobalt compounds, and manganese compounds, it is possible to improve light resistance (i.e., suppress photocatalytic activity) and control the particle shape during calcination.

[0052] In the titanium dioxide microparticles before calcination, the aluminum compound may be present in any state. For example, it may be dissolved as an aluminum component in the titanium dioxide microparticles together with a tin component, or it may be present as an aluminum compound on the surface of the titanium dioxide microparticles in which the tin component is dissolved.

[0053] The type of aluminum compound in the titanium dioxide fine particles before calcination is not particularly limited, but aluminum hydroxide is preferred. Examples of the crystalline structure of aluminum hydroxide include boehmite, gibbsite, pseudoboehmite, and bayerite, and include aluminum hydroxides and hydrated oxides. Multiple types of aluminum hydroxides with different crystalline structures may also be present.

[0054] Furthermore, in the titanium dioxide fine particles before calcination, one or more compounds selected from the group consisting of silicon compounds, cobalt compounds, and manganese compounds may be present in any state, and for example, may be solid-dissolved in the titanium dioxide fine particles together with the tin component as one or more components selected from the group consisting of silicon compounds, cobalt compounds, and manganese compounds, or may be present on the surface of the titanium dioxide fine particles in which the tin component has been solid-dissolved as one or more compounds selected from the group consisting of silicon compounds, cobalt compounds, and manganese compounds. Each component may be present in a different state from the others.

[0055] The fired product of the titanium dioxide fine particles and the aluminum compound may be in a state where at least a part of the aluminum component is solid-dissolved in the titanium dioxide fine particles, or the aluminum compound may be present on the surface of the titanium dioxide fine particles.

[0056] Furthermore, in the calcined product of the titanium dioxide fine particles, an aluminum compound, and one or more compounds selected from the group consisting of silicon compounds, cobalt compounds, and manganese compounds, in addition to the above, at least a portion of the one or more components selected from the group consisting of silicon components, cobalt components, and manganese components may be in a state of solid solution in the titanium dioxide fine particles or may be present on the surface of the titanium dioxide fine particles. Furthermore, each component may be present in a different state from each other.

[0057] The above phrase "may be present on the surface of the titanium dioxide microparticles" means that the entire titanium dioxide microparticles may be covered, or each compound (aluminum, silicon, cobalt, manganese) present on the surface of the titanium dioxide microparticles may form islands and cover only a portion of the surface.

[0058] The shape of the titanium dioxide fine particles used in the present invention is not particularly limited, and any shape such as spherical, rod-like, needle-like, spindle-like, plate-like, etc. The average primary particle diameter for particles having a shape other than spherical is defined as the average length of the minor axis in the case of rod-like, needle-like, or spindle-like particles, and as the average diagonal length of the face in the case of plate-like particles.

[0059] The average primary particle diameter of the titanium dioxide fine particles used in the present invention (meaning the titanium dioxide fine particles after calcination in the case of a calcined product of titanium dioxide fine particles and each compound) is preferably 1 nm or more and 50 nm or less, more preferably 3 nm or more and 40 nm or less, and even more preferably 5 nm or more and 30 nm or less.

[0060] The average primary particle diameter of the titanium dioxide fine particles used in the present invention is determined by measuring the primary particle diameter as a circle-equivalent diameter (Heywood diameter) of 200 or more randomly selected particles under an electron microscope, and calculating the median value in the number distribution of the particle diameters (this method is also referred to as the "electron microscopy method" in this application). Image analysis software may be used to calculate the average primary particle diameter of the titanium dioxide fine particles. For example, Mac View Version 4.0 (Mountec Co., Ltd.) may be used as the image analysis software.

[0061] Titanium dioxide fine particles having such an average primary particle size have higher visible light transmittance than titanium dioxide particles having a larger average primary particle size (for example, titanium dioxide particles used for pigment applications having an average primary particle size of approximately 0.2 to 0.5 μm).

[0062] Therefore, by using titanium dioxide fine particles having the above average primary particle size, an organic solvent dispersion with higher transparency can be obtained.

[0063] The aspect ratio of the titanium dioxide fine particles used in the present invention is preferably 1.0 or more and 2.5 or less, more preferably 1.0 or more and 2.0 or less. The aspect ratio is calculated as follows: For 200 or more primary particles randomly selected under an electron microscope, the major axis (the length of the long side of the circumscribing rectangle with the smallest area) and minor axis (the length of the short side of the circumscribing rectangle with the smallest area) are measured using image analysis software Mac View Version 4.0 (Mountec Co., Ltd.), and the aspect ratio (for each of the 200 or more primary particles) is calculated by dividing the major axis by the minor axis. The average value of the aspect ratios is defined as the "aspect ratio of the titanium dioxide fine particles used in the present invention."

[0064] The specific surface area of ​​the titanium dioxide particles used in the present invention is 40 m ２ / g or more 300m ２ / g or less, and ２ / g or more 200m ２ / g or less is more preferable, and 100m ２ / g or more 180m ２ By using titanium dioxide fine particles having such a specific surface area, an organic solvent dispersion having higher transparency can be obtained.

[0065] The specific surface area of ​​the titanium dioxide fine particles can be determined by the nitrogen adsorption method (BET method) using a flow-type automatic specific surface area measuring device (FlowSorb II 2300, manufactured by Shimadzu Corporation).

[0066] The crystalline structure of the titanium dioxide fine particles used in the present invention is not particularly limited, and those of anatase type, rutile type, brookite type, etc. However, since the rutile type has lower photocatalytic activity and a higher refractive index than the anatase type, it is preferable to use titanium dioxide fine particles having rutile crystals in order to more effectively impart high light resistance and a high refractive index to the coating film.

[0067] When the crystalline form of the titanium dioxide fine particles is rutile, the rutile content of the titanium dioxide fine particles is preferably 90% or more, more preferably 95% or more. The rutile content of the titanium dioxide fine particles is calculated based on the following formula: Rutile content (%) = (Hr / (Hr + Ha)) x 100, where Hr is the height of the maximum peak (2θ = 27.5° ± 0.5°) corresponding to the rutile crystal in the X-ray diffraction spectrum, and Ha is the height of the maximum peak (2θ = 25.2° ± 0.5°) corresponding to the anatase crystal in the X-ray diffraction spectrum.

[0068] The titanium dioxide fine particles used in the present invention usually have a compound species structure of titanium dioxide (TiO ２ ), but titanium dioxide (TiO ２ ), metatitanic acid (TiO ２ ・nH ２ O) and orthotitanic acid (Ti(OH) ４ ) may be contained as part of the composition.

[0069] The titanium dioxide fine particles used in the present invention may further have an inorganic compound present on the surface thereof.

[0070] As the inorganic compound to be present on the surface of titanium dioxide microparticles, general inorganic compounds can be used. For example, inorganic compounds containing silicon component (Si), zirconium component (Zr), zinc component (Zn), cobalt component (Co), iron component (Fe), niobium component (Nb), titanium component (Ti), cerium component (Ce), aluminum component (Al), indium component (In), and / or manganese component (Mn) can be used. The state of the inorganic compound can be metal, metal oxide, hydroxide, etc.

[0071] Only one type of these inorganic compounds may be present on the surface of the titanium dioxide fine particles, or multiple types may be present on the surface of the titanium dioxide fine particles. When multiple types of inorganic compounds are present, different inorganic compounds may be present alternately to form a layered structure, or may be present separately on the surface of the titanium dioxide fine particles.

[0072] The inorganic compound present on the surface may be a surface-treated product obtained by a known method, or in the case of a fired product of titanium dioxide microparticles, it may be a product in which an aluminum compound or a third component remains.

[0073] The coating amount of the inorganic compound in terms of oxide is TiO ２ On a mass basis, the content is preferably 0.3 mass % or more and 15 mass % or less, more preferably 0.5 mass % or more and 10 mass % or less, and even more preferably 0.7 mass % or more and 5 mass % or less.

[0074] The organic solvent dispersion of the present invention contains an organic solvent. The organic solvent used in the present invention is not particularly limited, and known organic solvents can be used.

[0075] The organic solvent used in the present invention may be, for example, a ketone or a (poly)alkylene glycol monoalkyl ether. The organic solvent may be reactive, and an acrylate monomer may be used.

[0076] Examples of ketones include methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, 2-heptanone, 3-heptanone, diacetone alcohol (4-hydroxy-4-methylpentan-2-one), and 4-hydroxy-4-methylhexan-2-one.

[0077] Examples of the (poly)alkylene glycol monoalkyl ethers include ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol mono-n-propyl ether, ethylene glycol mono-n-butyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol mono-n-propyl ether, diethylene glycol mono-n-butyl ether, triethylene glycol monomethyl ether, triethylene glycol monoethyl ether, propylene glycol monomethyl ether, propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether, propylene glycol monoethyl ether acetate, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, dipropylene glycol mono-n-propyl ether, dipropylene glycol mono-n-butyl ether, tripropylene glycol monomethyl ether, and tripropylene glycol monoethyl ether.

[0078] Examples of the acrylate monomer include benzyl acrylate, 3-phenoxybenzyl acrylate, 4-phenylbenzyl acrylate, ethoxylated o-phenylphenol acrylate, 1,6-hexanediol diacrylate, and trimethylolpropane acrylate.

[0079] The use of the organic solvent further improves the dispersibility of titanium dioxide fine particles in the organic solvent dispersion of the present invention. Furthermore, when a coating composition or a composition for nanoimprints is prepared, the organic solvent improves the compatibility between the organic solvent dispersion and the binder resin, thereby improving the coatability onto a substrate.

[0080] The organic solvent dispersion of the present invention contains a silane coupling agent. In the present application, the term "silane coupling agent" refers to an organosilicon compound having both an organic functional group X and a hydrolyzable group OR in one molecule.

[0081] The organic functional group X is generally preferably at least one selected from a methacryl group, an acrylic group, a vinyl group, an epoxy group, an amino group, a mercapto group, a sulfide group, an isocyanate group, etc. When a plurality of organic functional groups X are present in the molecule of the silane coupling agent, the X may be the same or different from each other.

[0082] In the hydrolyzable group OR, O represents an oxygen atom, and R represents a hydrogen atom or an alkyl group having 1 to 22 carbon atoms. The alkyl group may be linear, branched, or cyclic. When a plurality of hydrolyzable groups OR are present in a molecule of the silane coupling agent, the R may be the same or different from each other.

[0083] Examples of the silane coupling agent used in the present invention include methacrylsilane, acrylic silane, vinyl silane, epoxy silane, amino silane, mercapto silane, and isocyanate silane.

[0084] Examples of methacrylsilane include 3-methacryloxypropylmethyldimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropylmethyldiethoxysilane, 3-methacryloxypropyltriethoxysilane, and methacryloxyoctyltrimethoxysilane.

[0085] Acrylic silanes include 3-acryloxypropyltrimethoxysilane.

[0086] Examples of vinyl silanes include vinyltrimethoxysilane, vinyltriethoxysilane, and octenyltrimethoxysilane.

[0087] Examples of epoxy silanes include glycidoxypropyltrimethoxysilane and glycidoxyoctyltrimethoxysilane.

[0088] Examples of aminosilanes include 3-aminopropyltriethoxysilane, N-phenyl-3-aminopropyltrimethoxysilane, N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane, N-2-(aminoethyl)-3-aminopropylmethyltrimethoxysilane, and 3-aminopropyltrimethoxysilane.

[0089] Examples of mercaptosilane include 3-mercaptopropylmethyldimethoxysilane and 3-mercaptopropylmethyltrimethoxysilane.

[0090] Isocyanate silanes include 3-isocyanatepropyltriethoxysilane.

[0091] The organic solvent dispersion of the present invention contains a dispersant having a basic adsorptive group.

[0092] The dispersant having a basic adsorptive group used in the present invention is preferably an amine-based dispersant having an amino group, specifically, primary amine, secondary amine, tertiary amine or a salt thereof, and quaternary ammonium.

[0093] These amine-based dispersants contain an amino group as a basic adsorptive group, or a partial structure in which one or more hydrogen atoms of an amino group are substituted with an alkyl group or the like.

[0094] The amine value of the dispersant having a basic adsorptive group can be measured by a known method specified in ASTM D2074, JIS K 7237, etc. A specific method for measuring the amine value is described below. The amine value is the amount of base per 1 g of solids excluding organic solvents in a dispersant sample, expressed as the mass of equivalent KOH (mgKOH / g).

[0095] (Method for measuring amine value) 0.5 to 1.5 g of a dispersant sample is weighed out in a 100 mL beaker and dissolved in 50 mL of acetic acid. Then, using an automatic titrator equipped with a pH electrode, this solution is titrated to 0.1 mol / L HClO. ４Neutralization titration is performed with a (perchloric acid) acetic acid solution. The inflection point of the titration pH curve is set as the titration endpoint, and the amine value is calculated using the following formula: Amine value [mg KOH / g] = (561 × V) / (W × S) (where V is the titration amount [mL] at the titration endpoint, W is the weighed amount of dispersant sample [g], and S is the solids concentration [mass %] of the dispersant sample.)

[0096] Examples of dispersants having a basic adsorptive group that can be used in the present invention include commercially available products such as DISPERBYK (registered trademark)-163 (manufactured by BYK-Chemie, amine value: 10 mgKOH / g), Solsperse (registered trademark) 20000 (amine value: 32 mgKOH / g), Solsperse (registered trademark) 39000 (amine value: 25.7 mgKOH / g), and Solsperse (registered trademark) 56000 (amine value: 39 mgKOH / g) (all manufactured by Lubrizol), as well as 2-diethylaminoethyl methacrylate.

[0097] In the dispersant having a basic adsorptive group used in the present invention, if the amine value is greater than 5 mg KOH / g, the dispersant can be determined to have sufficiently high basicity, and the desired dispersion effect can be obtained in the organic solvent dispersion of the present invention.

[0098] In the organic solvent dispersion of the present invention, the mass ratio of the dispersant having a basic adsorptive group to the silane coupling agent is preferably 15% by mass or more and 75% by mass or less, more preferably 15% by mass or more and 70% by mass or less, and even more preferably 20% by mass or more and 70% by mass or less.

[0099] In the organic solvent dispersion of the present invention, the silane coupling agent is understood to function as a dispersing aid that facilitates deagglomeration of titanium dioxide fine particles in an aggregated state.

[0100] It is also understood that a dispersant having a basic adsorptive group inhibits the re-aggregation of titanium dioxide fine particles in an organic solvent after deaggregation.

[0101] In the organic solvent dispersion of the present invention, by using a dispersant having a basic adsorptive group in combination with a silane coupling agent, it is possible to reliably protect the surface of the titanium dioxide fine particles and to stabilize the dispersion.

[0102] For this reason, the mass ratio of the dispersant having a basic adsorption group to the silane coupling agent is preferably 15 to 75% by mass. By setting the mass ratio of the dispersant having a basic adsorption group to the silane coupling agent to 75% by mass or less, the content of the silane coupling agent is reduced, which is preferable because it can avoid the effect of impairing its function, i.e., its function of facilitating deagglomeration of titanium dioxide fine particles in an aggregated state in an organic solvent by wet dispersion, etc. Furthermore, by setting the mass ratio of the dispersant having a basic adsorption group to the above-mentioned 15% by mass or more, it can avoid the effect of reducing the content of the dispersant and preventing it from fully exhibiting its function.

[0103] The organic solvent dispersion of the present invention can be produced by dispersing titanium dioxide microparticles in which titanium components, tin components, and aluminum components are detected by X-ray fluorescence analysis and X-ray diffraction peaks attributable to rutile titanium dioxide (or only X-ray diffraction peaks attributable to rutile titanium dioxide) are observed by powder X-ray diffraction measurement, but no X-ray diffraction peaks attributable to tin components and aluminum components are observed, a silane coupling agent, and a dispersant having a basic adsorption group, in an organic solvent.

[0104] When dispersing the organic solvent dispersion, in addition to the silane coupling agent and the dispersant having a basic adsorption group, a dispersing aid, a dispersion stabilizer, an antifoaming agent, a thickener, inorganic oxide fine particles other than titanium dioxide fine particles, etc. may be added.

[0105] In the dispersion, a known dispersing machine can be used. For example, a paint shaker, a dissolver, a high-speed stirrer, a kneader, an ultrasonic dispersing machine, a high-pressure homogenizer, a ball mill, a bead mill, a sand mill, a horizontal media mill dispersing machine, a colloid mill, etc. can be used. The dispersion time in the dispersion can be adjusted appropriately depending on the type of dispersing machine and media used.

[0106] Among the above dispersers, a bead mill is preferably used to obtain an organic solvent dispersion having high dispersibility. Furthermore, when dispersing with a bead mill, it is preferable to use bead media. The diameter of the bead media is preferably 1 mm or less, and more preferably 0.5 mm or less.

[0107] The bead media is preferably made of ceramic, which can prevent discoloration of the dispersion and contamination with impurities originating from the bead media. Examples of ceramics include zirconia, alumina, and zircon.

[0108] The dispersion may be carried out once or multiple times. When the dispersion is carried out multiple times, it is preferable to carry out the dispersion separately, for example, in two steps: preliminary dispersion and main dispersion.

[0109] By carrying out the preliminary dispersion, the surface of the titanium dioxide fine particles in the organic solvent dispersion can be wetted, and the air layer on the surface of the titanium dioxide fine particles is thereby replaced with the organic solvent. By carrying out the main dispersion subsequently, the titanium dioxide fine particles in the organic solvent dispersion can be rapidly dispersed. As a result, the dispersibility of the titanium dioxide fine particles in the organic solvent is effectively improved, and the dispersion treatment time required to achieve the desired dispersed particle diameter can be shortened.

[0110] The preliminary dispersion and the main dispersion may use the same disperser and dispersing conditions, or different dispersers and dispersing conditions. It is preferable to use bead media with a smaller diameter in the main dispersion than in the preliminary dispersion. This can further enhance the dispersibility of titanium dioxide microparticles in organic solvents.

[0111] After the dispersion, it is preferable to remove aggregated titanium dioxide fine particles contained in the organic solvent dispersion by centrifugation.

[0112] The conditions for the centrifugation are preferably 2400 G or more and 30 minutes or more, which allows for sufficient removal of aggregated titanium dioxide fine particles contained in the organic solvent dispersion and improves the transparency of the organic solvent dispersion.

[0113] Titanium dioxide microparticles in which titanium components, tin components, and aluminum components are detected by the above-mentioned X-ray fluorescence analysis measurement, and X-ray diffraction peaks attributable to rutile titanium dioxide (or only X-ray diffraction peaks attributable to rutile titanium dioxide) are observed by powder X-ray diffraction measurement, but X-ray diffraction peaks attributable to tin components and aluminum components are not observed, can be produced, for example, by including the following steps.

[0114] The method for producing the organic solvent dispersion of the present invention includes the steps of: step (1): hydrolyzing a mixture of titanium (oxy)chloride and a tin compound, or hydrolyzing titanium (oxy)chloride in the presence of core particles of a tin compound (for example, core particles obtained by hydrolyzing a tin compound); step (2): mixing the product after the hydrolysis with an aluminum compound; and step (3): calcining the mixture of the product after the hydrolysis and the aluminum compound at a temperature of 250°C or higher and 1000°C or lower.

[0115] This allows for the production of titanium dioxide microparticles in which titanium components, tin components, and aluminum components are detected by X-ray fluorescence analysis, and X-ray diffraction peaks attributable to rutile titanium dioxide (or only X-ray diffraction peaks attributable to rutile titanium dioxide) are observed by powder X-ray diffraction measurement, but no X-ray diffraction peaks attributable to tin components or aluminum components are observed.

[0116] Preferably, titanium dioxide fine particles containing a tin component and an aluminum component in a solid solution can be obtained.

[0117] In titanium dioxide microparticles in which a tin component and an aluminum component are solid-dissolved, the method for dissolving the tin component and the aluminum component in the titanium dioxide microparticles is preferably a liquid phase method or a solid phase method, as described below, and it is more preferable to use a co-precipitation method as the liquid phase method and a high-temperature calcination method as the solid phase method.

[0118] A more preferred method is to dissolve the tin component in titanium dioxide fine particles by a liquid phase method and the aluminum component in titanium dioxide fine particles by a solid phase method.The most preferred method is to dissolve the tin component in titanium dioxide fine particles by a coprecipitation method and the aluminum component in titanium dioxide fine particles by a high-temperature calcination method.

[0119] Furthermore, in titanium dioxide microparticles in which a tin component, an aluminum component, and a third component are solid-dissolved, for example, a method for dissolving the tin component, the aluminum component, and the third component in the titanium dioxide microparticles may be a method in which the tin component is solid-dissolved in the titanium dioxide microparticles by a liquid phase method, and the aluminum component and the third component are solid-dissolved by a solid phase method.

[0120] A more preferred method is to form a solid solution of the tin component in titanium dioxide fine particles by a co-precipitation method, and then form a solid solution of the aluminum component and the third component by a solid phase method.An even more preferred method is to form a solid solution of the tin component in titanium dioxide fine particles by a co-precipitation method, and then form a solid solution of the aluminum component and the third component by a high-temperature calcination method.

[0121] <Step (1)> Step (1) in the present application is a step of hydrolyzing a mixture of titanium (oxy)chloride and a tin compound, or a step of hydrolyzing titanium (oxy)chloride in the presence of core particles obtained by hydrolyzing a tin compound. This step produces a hydrolysis product containing a tin component and a titanium component. Inclusion of a tin component during the production of titanium dioxide fine particles is preferred because it facilitates the production of rutile titanium dioxide. First, a method of hydrolyzing a mixture of titanium (oxy)chloride and a tin compound, which is one method of step (1), will be described.

[0122] As the titanium (oxy)chloride, titanium tetrachloride, titanium trichloride, titanium oxychloride, etc. can be used. Among these, titanium tetrachloride is preferred. The titanium (oxy)chloride may be used as a solution dissolved in water, etc. Here, titanium (oxy)chloride means titanium chloride and / or titanium oxychloride.

[0123] The concentration of the titanium (oxy)chloride is TiO ２ The concentration is preferably 45 g / L or more and 250 g / L or less, more preferably 100 g / L or more and 250 g / L or less, and even more preferably 150 g / L or more and 250 g / L or less, calculated as a conversion. By setting the concentration at 45 g / L or more, a sufficient production amount of the titanium dioxide fine particles used in the present invention can be ensured. By setting the concentration at 250 g / L or less, excessive hydrolysis of titanium (oxy)chloride can be preferably suppressed, and the titanium dioxide fine particles used in the present invention can be preferably and safely produced.

[0124] As the tin compound, tin (II) chloride, tin (IV) chloride, tin sulfate, tin nitrate, tin acetate, tin oxychloride, etc. can be used. Among them, tin (IV) chloride is preferable. Furthermore, as the tin compound, a solution in which a tin compound is dissolved in a solvent such as water can be used. Incidentally, tin (IV) chloride and tin tetrachloride (i.e., SnCl ４ ) refer to the same compound.

[0125] The tin compound may be a mixture of a tin compound and a known acid. Examples of the acid that can be used include hydrochloric acid, sulfuric acid, and nitric acid, and an aqueous solution of the acid may also be used. The order in which the tin compound and the acid are mixed is not limited; the acid may be mixed with the tin compound, the acid may be mixed with the tin compound, or the acid and the tin compound may be mixed simultaneously.

[0126] The concentration of the tin compound in the acid is not particularly limited, and may be expressed in terms of oxide (SnO ２ ) is preferably 0.1 g / L or more and 15 g / L or less, and more preferably 2 g / L or more and 7 g / L or less. For example, the concentration of tin chloride in the hydrochloric acid aqueous solution described below is not particularly limited. For example, tin chloride may be used in the form of an oxide (SnO ２ When the concentration of the tin compound (e.g., tin chloride) is within the above range, it is possible to prevent the tin compound (e.g., tin chloride) from being hydrolyzed alone and precipitating.

[0127] The concentration of the acid is not particularly limited. For example, when an aqueous solution of hydrochloric acid is used as the acid, the concentration of the hydrochloric acid is preferably 1 g / L or more and 15 g / L or less, and more preferably 3 g / L or more and 10 g / L or less. When the concentration of the hydrochloric acid is within the above range, it is possible to prevent the tin compound (e.g., tin chloride) from being hydrolyzed and precipitated alone.

[0128] By hydrolyzing the mixture of the tin compound (for example, tin chloride) and titanium (oxy)chloride, a hydrolysis product containing a tin component and a titanium component can be obtained.

[0129] When mixing the tin compound and the titanium (oxy)chloride, the order of mixing them is not particularly limited. The titanium (oxy)chloride (or the aqueous solution of titanium (oxy)chloride) may be mixed with the tin compound (or the aqueous solution of tin compound), the titanium (oxy)chloride may be mixed with the tin compound, or the tin compound and the titanium (oxy)chloride may be mixed simultaneously. The tin compound (for example, tin chloride) converts the tin component into an oxide, SnO ２ The amount converted to SnO ２ amount) is a titanium component of the titanium (oxy)chloride, and the titanium component is converted to an oxide, TiO ２ The amount converted to TiO ２ The mass ratio of oxide (SnO ２ Amount / TiO ２ The amount of the hydroxybenzoates is preferably 0.1% by mass or more and 20% by mass or less, more preferably 2% by mass or more and 7% by mass or less.

[0130] The hydrolysis is preferably carried out by heating a mixture of a tin compound (e.g., tin chloride) and titanium (oxy)chloride to a temperature of preferably 40°C or higher and 110°C or lower, more preferably 50°C or higher and 110°C or lower, and even more preferably 60°C or higher and 110°C or lower.

[0131] When the mixture of the tin compound and the titanium (oxy)chloride is heated, the tin compound (or titanium (oxy)chloride) may be heated in advance to a predetermined temperature and then mixed with the titanium (oxy)chloride (or tin compound), or both may be mixed and then heated to the predetermined temperature. Of these, it is preferable to heat the tin compound in advance to a predetermined temperature and then mix the titanium (oxy)chloride therewith.

[0132] In this way, the tin component and the titanium component are hydrolyzed and coprecipitated almost simultaneously. The hydrolysis time can be set appropriately.

[0133] As an alternative to step (1), a hydrolysis product containing tin and titanium components can also be obtained by hydrolyzing titanium (oxy)chloride in the presence of core particles of a tin compound (for example, core particles obtained by hydrolyzing the above-mentioned tin compound). Incorporation of a tin component during the production of titanium dioxide fine particles is preferred because it facilitates the production of rutile titanium dioxide.

[0134] The core particles may be commercially available products or may be synthesized by hand. Examples of methods for synthesizing the core particles by hand include a method of heating an acidic aqueous solution of a tin compound. For example, tin chloride (e.g., SnCl ４ ) is prepared and heated at a temperature of 40° C. to 80° C. to obtain fine particles of a tin compound that will become core particles. The tin compound and acid can be those described above.

[0135] The concentration of the tin compound (e.g., tin chloride) in the hydrochloric acid aqueous solution is not particularly limited. For example, the tin compound (e.g., tin chloride) may be present in an amount of 1000 ppm or less in terms of oxide (SnO ２ ) is preferably 0.1 g / L or more and 15 g / L or less, and more preferably 2 g / L or more and 7 g / L or less.

[0136] The concentration of hydrochloric acid is not particularly limited. For example, it is preferably 1 g / L or more and 15 g / L or less, and more preferably 3 g / L or more and 10 g / L or less.

[0137] By hydrolyzing titanium (oxy)chloride in the presence of core particles, a hydrolysis product containing tin and titanium components can be obtained. The titanium (oxy)chloride can be the same as described above. When an aqueous titanium (oxy)chloride solution is used, its concentration is preferably in the range described above.

[0138] The hydrolysis is preferably carried out by heating titanium (oxy)chloride in the presence of core particles, and the temperature at which the mixture is heated is preferably 40° C. or higher and 110° C. or lower, more preferably 50° C. or higher and 110° C. or lower.

[0139] In this way, the titanium (oxy)chloride can be sufficiently hydrolyzed using the fine particles of the tin compound as nuclei. The hydrolysis time can be set appropriately.

[0140] The above-mentioned step of hydrolyzing a mixture of titanium (oxy)chloride and a tin compound, the step of hydrolyzing the tin compound, and the step of hydrolyzing titanium (oxy)chloride in the presence of core particles may be carried out with stirring using a known stirrer such as a blade stirrer, a disper, or a homomixer.

[0141] After the hydrolysis reaction, the hydrolysis product may be further aged.

[0142] The conditions for the aging step are not particularly limited. Specifically, it is preferable to maintain the temperature of the hydrolysis reaction (e.g., neutralization reaction) and perform aging for 1 minute to 48 hours. The aging time is more preferably 5 minutes to 24 hours, and even more preferably 10 minutes to 12 hours.

[0143] Furthermore, a step of adjusting the pH may be carried out after the aging step. The pH is preferably 5 or more and 9 or less, more preferably 6 or more and 8 or less. This makes it possible to suppress unexpected hydrolysis in the subsequent steps. Depending on the pH before adjustment, an acid or an alkali may be used. Examples of acids include sulfuric acid, hydrochloric acid, and nitric acid. Examples of alkalis include sodium hydroxide, potassium hydroxide, and ammonia.

[0144] In the step (1), when the titanium (oxy)chloride is hydrolyzed, a carboxylic acid or a salt thereof may be mixed therewith.

[0145] Specific examples of the process include a process of hydrolyzing a mixture of the titanium (oxy)chloride, a tin compound, and a carboxylic acid or a salt thereof, or a process of adding titanium (oxy)chloride and a carboxylic acid or a salt thereof in the presence of core particles of a tin compound (for example, core particles obtained by hydrolyzing a tin compound) and hydrolyzing the mixture.

[0146] The carboxylic acid or its salt converts the titanium component of titanium (oxy)chloride to TiO ２ When converted to oxide, 1 mol of the TiO ２ It is preferable to mix the fluorine-containing compound so that the content is 0.3 mol % or more and 3 mol % or less, and more preferably 0.5 mol % or more and 2 mol % or less.

[0147] The titanium dioxide fine particles obtained by the production method including the above-mentioned carboxylic acid or its salt can be prevented from agglomerating during the subsequent drying step and from sintering during the firing step, and therefore can be dispersed in an organic solvent without being subjected to a pulverization step, resulting in a highly transparent organic solvent dispersion.

[0148] The order in which the titanium (oxy)chloride, tin compound, and carboxylic acid or a salt thereof are mixed is not particularly limited. The titanium (oxy)chloride and carboxylic acid or a salt thereof may be mixed first, and then mixed with the tin compound; the titanium (oxy)chloride, tin compound, and carboxylic acid or a salt thereof may be mixed simultaneously; or the tin compound and carboxylic acid or a salt thereof may be mixed first, and then mixed with titanium (oxy)chloride.

[0149] Among these, it is preferable to mix titanium (oxy)chloride with a carboxylic acid or a salt thereof in advance, and then add the mixture to the tin compound.

[0150] The carboxylic acid or salt thereof includes a monocarboxylic acid, a poly(poly)carboxylic acid, or a salt thereof, and examples thereof include the following (a) to (g): (a) carboxylic acid: for example, formic acid, acetic acid, propionic acid; (b) poly(poly)carboxylic acid: particularly, a dicarboxylic acid or a tricarboxylic acid, for example, oxalic acid, fumaric acid; (c) hydroxypoly(poly)carboxylic acid: particularly, a hydroxycarboxylic acid or a hydroxytricarboxylic acid, for example, malic acid, citric acid, or tartronic acid; (d) polyhydroxymonocarboxylic acid: for example, glucoheptonic acid, gluconic acid; (e) poly(poly)-hydroxycarboxylic acid: for example, tartaric acid; (f) dicarboxylic amino acid and its corresponding amide: for example, aspartic acid, asparagine (2-amino-3-carbamoylpropionic acid), glutamic acid; and (g) hydroxylated or non-hydroxylated monocarboxylic amino acid: for example, lysine, serine, threonine.

[0151] The carboxylic acid is preferably a hydroxypoly(polyvalent)carboxylic acid, more preferably citric acid. Any salt of the carboxylic acid may be used without limitation, for example, an alkali metal salt such as sodium or potassium, or an ammonium salt.

[0152] <Step (2)> In the present application, step (2) is a step of mixing the hydrolysis product containing the tin and titanium components with an aluminum compound. This allows the aluminum component to diffuse into the hydrolysis product by calcination in the subsequent step (3), resulting in titanium dioxide microparticles in which the titanium component, tin component, and aluminum component are detected by X-ray fluorescence analysis, and X-ray diffraction peaks attributable to rutile titanium dioxide are observed by powder X-ray diffraction measurement, but X-ray diffraction peaks attributable to the tin and aluminum components are not observed. The mixing state is not particularly limited, and any state may be achieved using a known mixing method. For example, the hydrolysis product particles and the aluminum compound particles may be uniformly mixed, or the aluminum compound may be present on the surfaces of the hydrolysis product particles. Examples of the latter include aluminum compound particles attached to the surfaces of the hydrolysis product particles, or the surfaces of the hydrolysis product particles may be coated with an aluminum compound layer. The presence of the aluminum compound on the surfaces of the hydrolysis product particles is particularly preferred, and the presence of the aluminum compound on the surfaces of the hydrolysis product particles is even more preferred.

[0153] The order of the mixing step is not particularly limited. The aluminum compound may be added to the hydrolyzed product and mixed therewith, or the hydrolyzed product may be added to the aluminum compound and mixed therewith, or the hydrolyzed product and the aluminum compound may be mixed simultaneously. Among these, it is preferable to add the aluminum compound to the hydrolyzed product and mix them. By doing so, the aluminum compound can be present on the surface of the hydrolyzed product.

[0154] When the hydrolysis product is mixed with the aluminum compound, one or more compounds selected from the group consisting of silicon compounds, cobalt compounds and manganese compounds may be further mixed.

[0155] When one or more compounds selected from the group consisting of silicon compounds, cobalt compounds and manganese compounds are mixed, the mixing may be carried out in the same manner as in the mixing of the hydrolysis product with the aluminum compound.

[0156] The term "present on the surface" may mean that the hydrolysis product is entirely covered, or that the hydrolysis product is in the form of islands and covers only a part of the surface of the hydrolysis product, but it is preferable that the hydrolysis product is entirely covered.

[0157] A specific example of a method for coating the surface of the hydrolysis product with an aluminum compound component is a method in which, when the hydrolysis product is mixed with an aluminum compound, an acid or an alkali is mixed therewith, and aluminum hydroxide is precipitated on the surface of the hydrolysis product by a neutralization reaction.

[0158] Examples of the aluminum compound include aluminum halides such as aluminum chloride, compounds of aluminum with inorganic acids such as aluminum chloride, aluminum nitrate, and aluminum sulfate, and aluminum oxoacid metal salts such as sodium aluminate. These aluminum compounds may be used alone or in combination of two or more. The aluminum compound may be used as a powder or may be used as a solution by dissolving it in a solvent such as water.

[0159] Examples of the silicon compound include silicates such as sodium silicate and potassium silicate. The silicon compound may be used in the form of powder, or may be used as a solution by dissolving it in a solvent such as water.

[0160] Examples of the cobalt compound include cobalt(II) chloride, cobalt(III) chloride, cobalt(II) sulfide, cobalt(II) sulfate, cobalt(II) nitrate, cobalt(II) carbonate, and cobalt(II) acetate. Hydrates of the cobalt compound may also be used. The cobalt compound may be used as a powder or may be dissolved in a solvent such as water to form a solution.

[0161] Examples of the manganese compound include manganese(II) chloride, manganese(II) sulfide, manganese(II) sulfate, manganese(II) nitrate, manganese(II) phosphate, manganese(II) carbonate, and manganese(II) acetate. Hydrates of the manganese compounds may also be used. The cobalt compound may be used as a powder or may be dissolved in a solvent such as water to form a solution.

[0162] The aluminum compound converts the titanium component in the hydrolysis product into an oxide (TiO ２ ) converted into the amount (TiO ２ Amount of oxide (Al ２ O ３ ) converted into the amount (Al ２ O ３ When expressed in terms of mass ratio (Al ２ O ３ Amount / TiO ２ The amount of the hydroxybenzoates is preferably 0.5% by mass or more and 10% by mass or less, and more preferably 2% by mass or more and 8% by mass or less.

[0163] The silicon compound converts the titanium component in the hydrolysis product into an oxide (TiO ２ ) converted into the amount (TiO ２ Amount) of oxide (SiO ２ ) converted into the amount (SiO ２ When expressed in terms of mass ratio (SiO ２ Amount / TiO ２ The amount of the hydroxybenzoates is preferably 0.5% by mass or more and 10% by mass or less, and more preferably 1% by mass or more and 5% by mass or less.

[0164] The cobalt compound converts the titanium component in the hydrolysis product into an oxide (TiO ２ ) converted into the amount (TiO ２ Amount) of oxide (Co ２ O ３ ) converted into the amount (Co ２ O ３ When expressed in terms of mass ratio (Co ２ O ３Amount / TiO ２ The amount of the hydroxybenzoates is preferably 0.05% by mass or more and 5% by mass or less, and more preferably 0.07% by mass or more and 3% by mass or less.

[0165] The manganese compound converts the titanium component in the hydrolysis product into an oxide (TiO ２ ) converted into the amount (TiO ２ When expressed as the amount converted into oxide (MnO) (MnO amount) relative to the amount of TiO, the mass ratio converted into oxide (MnO amount / TiO ２ The amount of the hydroxybenzoates is preferably 0.05% by mass or more and 5% by mass or less, and more preferably 0.07% by mass or more and 3% by mass or less.

[0166] Examples of the acid include inorganic acids such as sulfuric acid, hydrochloric acid, and nitric acid, and these acids may be used alone or in combination of two or more. Examples of the alkali include inorganic bases such as alkali metal hydroxides such as sodium hydroxide and potassium hydroxide, alkali metal carbonates such as sodium carbonate and potassium carbonate, and ammonia, and these alkalis may be used alone or in combination of two or more.

[0167] Whether to use an acid or an alkali may be appropriately selected depending on the aluminum compound to be mixed. For example, when alkaline sodium aluminate is used as the aluminum compound, an acid may be used.

[0168] In the neutralization reaction, the order in which the hydrolysis product, the aluminum compound, and the acid or alkali are mixed is not particularly limited.

[0169] For example, an aluminum compound may be added to the hydrolyzed product, and then an acid or alkali may be added; an acid or alkali may be added to the hydrolyzed product, and then an aluminum compound may be added; or an aluminum compound and an acid or alkali may be added to the hydrolyzed product simultaneously.

[0170] Among these, it is preferable to add an aluminum compound to the hydrolysis product, and then add an acid or alkali.

[0171] The pH in the neutralization reaction is preferably 4 or more and 7 or less, and more preferably 5 or more and 6 or less. By setting the pH in the neutralization reaction within this range, the aluminum compound can be sufficiently precipitated as hydroxide, and the surface of the hydrolysis product can be uniformly coated with aluminum hydroxide.

[0172] The pH in the neutralization reaction can be adjusted by the amount of acid or alkali added during the reaction.

[0173] The reaction temperature in the neutralization reaction is preferably 40° C. or higher and 90° C. or lower, and more preferably 55° C. or higher and 80° C. or lower. By setting the reaction temperature in the neutralization reaction within this range, the surface of the hydrolysis product can be uniformly coated with aluminum hydroxide.

[0174] The neutralization reaction may be carried out under stirring using a known stirrer such as a blade stirrer, a disper, or a homomixer.

[0175] After the neutralization reaction, the hydrolysis product coated with aluminum hydroxide may be further aged.

[0176] The conditions for the aging step are not particularly limited. Specifically, the aging step is preferably performed for 1 minute to 48 hours while maintaining the temperature of the neutralization reaction. The aging time is more preferably 5 minutes to 24 hours, and even more preferably 10 minutes to 12 hours.

[0177] The hydrolysis product coated with aluminum hydroxide obtained by the neutralization reaction may be subjected to solid-liquid separation by a known method, if necessary, and the solid content may be dried to obtain a powder.

[0178] In the case where one or more compounds selected from the group consisting of silicon compounds, cobalt compounds, and manganese compounds are used in the series of steps from the step of selecting the acid or alkali to be used to the step of performing solid-liquid separation and drying the solid content, the steps may be carried out in the same manner as described in the series of steps for the aluminum compound.

[0179] For the solid-liquid separation, a known filtration method can be used. For example, a pressure filtration device such as a rotary press or a filter press, which is usually used industrially, or a vacuum filtration device such as a Nutsche filter or a Moore filter can be used.

[0180] In the solid-liquid separation operation, washing may be performed using pure water or various organic solvents, etc., as needed. Among these, it is preferable to perform washing with pure water using a filter press or a Nutsche filter, with the conductivity of the filtrate being approximately 1500 Ω cm or more.

[0181] The drying conditions are not particularly limited. For example, the drying temperature is preferably 100° C. or higher and 250° C. or lower, more preferably 120° C. or higher and 220° C. or lower, and even more preferably 140° C. or higher and 180° C. or lower. The drying time is preferably 30 minutes to 72 hours, more preferably 1 hour to 48 hours, and even more preferably 6 hours to 24 hours.

[0182] <Step (3)> Step (3) in the present application is a step of calcining the mixture of the hydrolysis product and the aluminum compound at a temperature of 250°C or higher and 1000°C or lower.

[0183] The temperature in the firing is more preferably 300°C or higher and 800°C or lower, even more preferably 350°C or higher and 750°C or lower, and most preferably 420°C or higher and 720°C or lower.

[0184] The firing time and firing atmosphere can be set appropriately. Specifically, the firing time is preferably 30 minutes to 24 hours, more preferably 1 hour to 18 hours. The firing atmosphere is preferably air.

[0185] The calcination conditions for the case where the hydrolysis product contains, in addition to the aluminum compound, one or more compounds selected from the group consisting of silicon compounds, cobalt compounds, and manganese compounds may be the same as those described above.

[0186] The sample obtained after the calcination may be pulverized by a known method, including but not limited to dry pulverization or wet pulverization, using a pulverizer such as a paint shaker, dissolver, high-speed agitator, ultrasonic disperser, high-pressure homogenizer, bead mill, sand mill, horizontal media mill disperser, colloid mill, crusher, hammer mill, jet mill, or attritor mill.

[0187] The pulverization step may be carried out, for example, by wet pulverization as described below.

[0188] The sample obtained after firing is mixed with pure water to prepare a slurry. The concentration of the slurry is not particularly limited, but is preferably 100 g / L or more and 300 g / L or less. A concentration of 100 g / L or more is preferable because it can increase the yield, and a concentration of 300 g / L or less is preferable because it can efficiently suppress thickening of the slurry. In addition, to improve the dispersibility of the slurry, a known dispersant may be added, or a pH adjuster may be added to adjust the pH.

[0189] As a guideline for the pulverization step, it is preferable to pulverize the slurry until the cumulative 90% diameter (Laser Diffraction: LD90) on a volume basis of the slurry measured by a laser diffraction / scattering method becomes 3.5 μm or less.

[0190] By doing so, the particle size distribution of the titanium dioxide fine particles in the organic solvent dispersion can be set within a preferred range. The pulverization step may be performed once or twice or more times. The measurement conditions using the laser diffraction / scattering method are as follows. Measurement conditions: Apparatus: LA-950 manufactured by Horiba, Ltd. Conditions: (1) Particle refractive index: 2.75; (2) Solvent refractive index: 1.333; (3) Circulation speed: 5; (4) Ultrasonic intensity: 5; (5) Ultrasonic time: 3 minutes; (6) Stirring intensity: 5; and (7) Measurement solvent: 0.3% aqueous sodium hexametaphosphate solution adjusted to pH 10 with NaOH.

[0191] After the wet grinding of the slurry, if necessary, solid-liquid separation may be performed by a known method, and the resulting solid may be dried to obtain a powder. For the solid-liquid separation, a known filtration method can be used, for example, a pressure filtration device such as a rotary press or a filter press, or a vacuum filtration device such as a Nutsche filter or a Moore filter, which are commonly used industrially.

[0192] In the solid-liquid separation operation, washing may be performed using pure water or various organic solvents, etc., as needed. Among these, it is preferable to perform washing with pure water using a filter press or a Nutsche filter, with the conductivity of the filtrate being approximately 1500 Ω cm or more.

[0193] The drying conditions are not particularly limited. For example, the drying temperature is preferably 100° C. or higher and 250° C. or lower, more preferably 120° C. or higher and 220° C. or lower, and even more preferably 140° C. or higher and 180° C. or lower.

[0194] The drying time is preferably from 30 minutes to 72 hours, more preferably from 1 hour to 48 hours, and even more preferably from 6 hours to 24 hours.

[0195] The titanium dioxide fine particles preferably contain a tin component and an aluminum component as a solid solution. There are no particular limitations on the method for dissolving the tin component and the aluminum component in the titanium dioxide fine particles.

[0196] As a method for dissolving the tin component and the aluminum component in titanium dioxide fine particles, generally, known methods such as a gas phase method (such as a chemical vapor deposition (CVD) method or a physical vapor deposition (PVD) method), a liquid phase method (such as a hydrothermal method, a sol-gel method or a co-precipitation method), or a solid phase method (high-temperature calcination method) can be used.

[0197] Among these, for titanium dioxide microparticles in which tin and aluminum components are solid-dissolved, it is preferable to use the liquid phase method or solid phase method described above as a method for dissolving the tin and aluminum components in the titanium dioxide microparticles, and it is more preferable to use co-precipitation as the liquid phase method and high-temperature calcination as the solid phase method.

[0198] A more preferred method is to dissolve the tin component by a liquid phase method and dissolve the aluminum component by a solid phase method, and the most preferred method is to dissolve the tin component by a coprecipitation method and dissolve the aluminum component by a high-temperature firing method.

[0199] After the firing step (step (3)), the obtained titanium dioxide fine particles may be further surface-coated with an inorganic compound.

[0200] As a method for coating the surface of the titanium dioxide fine particles that have been subjected to the calcination process with an inorganic compound, a known surface treatment method can be used. Specifically, it is preferable to prepare a slurry containing the calcined titanium dioxide fine particles, add an inorganic compound to this slurry, and coat the surface of the titanium dioxide fine particles. It is more preferable to neutralize the inorganic compound in the slurry containing the calcined titanium dioxide fine particles, and precipitate the inorganic compound on the surface of the titanium dioxide fine particles to coat the surface of the titanium dioxide fine particles. Alternatively, the powder of titanium dioxide fine particles and the inorganic compound may be mixed in a dry state to coat the surface of the titanium dioxide fine particles with the inorganic compound.

[0201] The coating composition of the present invention contains the above-mentioned organic solvent dispersion of titanium dioxide fine particles and a binder resin.

[0202] Since the organic solvent dispersion of the present invention has high transmittance, a coating film having high visible light transmittance (transparency) can be formed by using a coating composition containing this organic solvent dispersion. Furthermore, since titanium dioxide fine particles have a high refractive index, a coating film having a high refractive index can also be formed by using a coating composition containing them.

[0203] The binder resin used in the coating composition is not particularly limited as long as the stability, high refractive index, and visible light transmittance (transparency) of the coating film obtained from the coating composition are ensured.

[0204] Examples of binder resins that can be used include alkyd resins, acrylic resins, melamine resins, urethane resins, epoxy resins, silicone resins, polyester resins, polyamic acid resins, polyimide resins, styrene-maleic acid resins, and styrene-maleic anhydride resins.

[0205] Preferred resins include urethane resins, acrylic resins, polyamic acid resins, polyimide resins, styrene-maleic acid resins, and styrene-maleic anhydride resins.

[0206] The binder resin may be used alone or in combination of two or more. Furthermore, various acrylic acid monomers and acrylate monomers are also applicable.

[0207] The coating composition of the present invention may contain various additives in addition to the organic solvent dispersion of titanium dioxide fine particles and the binder resin, such as dispersants, pigments, fillers, aggregates, thickeners, flow control agents, leveling agents, curing agents, crosslinking agents, curing catalysts, and curing polymerization initiators.

[0208] The coating composition of the present invention can be prepared by mixing the above-mentioned organic solvent dispersion of titanium dioxide fine particles, the binder resin, and, if necessary, the above-mentioned additives. In the mixing step, it is preferable to use, for example, the above-mentioned dissolver or high-speed stirrer.

[0209] The organic solvent dispersion or coating composition of the present invention can form a coating film. Specifically, the organic solvent dispersion or coating composition of the present invention can be applied to a substrate by any method, and then dried and / or baked as necessary to form a coating film on the substrate.

[0210] The substrate is not particularly limited, and various materials such as glass, polymer, ceramic, and metal can be used.

[0211] The coating method is not particularly limited, and known methods can be used, such as coating methods using a spin coater, dip coater, die coater, slit coater, bar coater, gravure coater, etc., the LB (Langmuir-Blodgett) film method, the self-assembly method, and spray coating.

[0212] There are no particular limitations on the drying method and the firing method, and known methods can be used. Examples include heat drying under normal pressure or reduced pressure, natural drying, etc. The heating method for heat drying and firing is also not particularly limited, and examples include heating methods using devices such as a hot plate or oven. The drying temperature is preferably 80°C or higher and 150°C or lower, and the firing temperature is preferably approximately 150°C or higher and 400°C or lower.

[0213] The thickness of the coating film can be appropriately set depending on the application, but is preferably, for example, from 0.005 μm to 2 μm, and more preferably from 0.01 μm to 1 μm.

[0214] The haze value is also affected by the film thickness, but is preferably 5% or less, more preferably 2.5% or less, and even more preferably 1.5% or less. The haze of the coating film can be measured using a haze meter in accordance with JIS K 7136. In addition, the refractive index of the coating film is preferably 1.60 or more, and more preferably 1.80 or more, when the coating film is used as a high refractive index layer. The refractive index can be measured and calculated by ellipsometry.

[0215] The coating film formed on the substrate may be laminated in multiple layers. In the case of multilayer lamination, each layer may be a coating film of the same quality or a combination of different coating films. In addition, an anti-reflection film can be formed on the substrate by alternately laminating the high refractive index layer and the low refractive index layer on the substrate.

[0216] The antireflection film may have any configuration as long as it includes the high refractive index layer, for example, an antireflection film having a high refractive index layer and a low refractive index layer in this order on a substrate, or an antireflection film having a low refractive index layer, a high refractive index layer, and a low refractive index layer in this order on a substrate. In such a layer configuration, a desired antireflection film can be designed by adjusting the film thickness and refractive index of each layer.

[0217] The nanoimprint composition of the present invention contains the above-mentioned organic solvent dispersion of titanium dioxide fine particles and a binder resin, and may further contain various additives as required.

[0218] In the present application, "for nanoimprinting" means that the composition is used in nanoimprint lithography, a method for forming a fine pattern, in which a mold having a predetermined pattern is pressed against a curable film formed on a substrate to transfer the pattern of the mold to the curable film.

[0219] Furthermore, "nanoimprint" refers to pattern transfer with a size of several nm to several μm, and is not limited to the nano-order.

[0220] The binder resin and various additives used in the nanoimprinting composition of the present invention may be the same as those used in the coating composition, and the method for preparing the nanoimprinting composition may be the same as the method for preparing the coating composition.

[0221] Furthermore, when the nanoimprint composition is used by applying it to a substrate, it can be used in the same manner as a coating film using the above-mentioned coating composition.

[0222] The nanoimprint composition of the present invention contains the above-mentioned organic solvent dispersion of titanium dioxide fine particles, and therefore has high transparency and a high refractive index, and can therefore be used in applications requiring high transparency and low haze, such as 3D sensors for autonomous driving and AR (augmented reality) waveguides in AR glasses.

[0223] Examples and comparative examples are shown below, but the present invention is not limited to these examples.

[0224] [Manufacture example 1] SnO ２ Hydrochloric acid (manufactured by Kanto Chemical Co., Ltd.) was added to a tin tetrachloride aqueous solution (manufactured by Nippon Chemical Industry Co., Ltd.) so that the concentration of TiO was 3 g / L and the concentration of hydrochloric acid was 5 g / L, and the mixture was stirred to prepare a hydrochloric acid-containing tin tetrachloride aqueous solution. The hydrochloric acid-containing tin tetrachloride aqueous solution was heated to 60°C, and TiO ２ SnO ２ A titanium tetrachloride aqueous solution (TiO ２To the solution, 50 g / L of sodium hydroxide (equivalent to 500 mg / L of sodium hydroxide, manufactured by Ishihara Sangyo Kaisha) was added over 15 minutes, the temperature was raised to 100°C, and after reaching 100°C, the solution was aged for 1 hour. After aging, while the solution was allowed to cool, 20% aqueous sodium hydroxide solution was added until the pH of the solution reached 7.0±0.2. The solution temperature at the end of the addition of the aqueous sodium hydroxide solution (manufactured by Takasugi Pharmaceutical Co., Ltd.) was 70°C. Next, while the solution temperature was maintained at 70°C, TiO ２ Al per 100 parts by mass ２ O ３ A sodium aluminate aqueous solution was added over 20 minutes so that the total weight of the solution was 6 parts by mass, and then the solution was aged for 20 minutes. After aging, a 20% aqueous sulfuric acid solution (manufactured by Ishihara Sangyo Kaisha) was added over 40 minutes to adjust the pH of the liquid to 5.5±0.2, and then the solution was aged for 1 hour. After aging, the solution was filtered using a filter press and washed with pure water until the filtrate conductivity reached 1500 Ω·cm or more, and the solid content was recovered. The recovered solid content was dried at 150°C for 8 hours, and the obtained dried product was heated from room temperature to 510-550°C over 7 hours in an electric furnace under air atmosphere, and then calcined at 510-550°C for 2 hours to obtain a calcined product. The calcined product was dispersed in pure water to a concentration of 150 g / L, and P was added to the dispersion. ２ O ５Sodium pyrophosphate (manufactured by Mitsui Chemicals, Shimonoseki Co., Ltd.) was added to a concentration of 2% by mass, and then an aqueous sodium hydroxide solution (manufactured by Takasugi Pharmaceutical Co., Ltd.) was added to adjust the pH of the liquid to 10.5 to prepare a slurry. The slurry was dispersed in a wet mill (Star Mill LME20, manufactured by Ashizawa Finetech Co., Ltd.) filled with 0.5 mm zirconia beads (manufactured by Toray Industries, Inc.) until the cumulative 90% diameter (LD90) on a volume basis measured by laser diffraction / scattering method was 3 μm or less. The wet milling was carried out under conditions of a feed rate of 3.2 L / min and a residence time of 2 minutes and 30 seconds. A 20% aqueous sulfuric acid solution was added to the dispersed slurry, and the pH of the slurry was adjusted to 6.7±0.2. The pH-adjusted slurry was filtered using a filter press and washed with pure water until the filtrate conductivity was 1500 Ω·cm or more, and the solid content was recovered. The recovered solid content was dried in a dryer at 150°C for 8 hours. After drying, the solid was pulverized using a hammer mill (Micropulverizer AP-1SH, manufactured by Hosokawa Micron Corporation) to obtain Sample 1 of Production Example 1. The hammer mill was operated under the following conditions: feed rate 500 g / min, rotation speed 9500 rpm, and screen diameter 1 mmφ. The average primary particle diameter of Sample 1 was 18 nm. The measurement conditions using the laser diffraction / scattering method were as follows: Measurement conditions: Apparatus: LA-950 manufactured by Horiba, Ltd. (1) Particle refractive index: 2.75; (2) Solvent refractive index: 1.333; (3) Circulation rate: 5; (4) Ultrasonic intensity: 5; (5) Ultrasonic time: 3 minutes; (6) Stirring intensity: 5; and (7) Measurement solvent: 0.3% aqueous sodium hexametaphosphate solution adjusted to pH 10 with NaOH.

[0225] [Manufacture example 2] SnO ２ Hydrochloric acid (manufactured by Kanto Chemical Co., Ltd.) was added to a tin tetrachloride aqueous solution (manufactured by Nippon Chemical Industry Co., Ltd.) so that the concentration of TiO was 3 g / L and the concentration of hydrochloric acid was 8 g / L, and the mixture was stirred to prepare a hydrochloric acid-containing tin tetrachloride aqueous solution. ２ Titanium tetrachloride (TiO) to which citric acid (manufactured by Showa Kako Co., Ltd.) was added so that the concentration was 1 mol% per 1 mol of titanium tetrachloride. ２ The aqueous solution of tin tetrachloride containing hydrochloric acid was heated to 60°C, and TiO ２SnO ２ The titanium tetrachloride aqueous solution was added over 15 minutes so that the titanium tetrachloride content was 5 parts by mass, and the solution was aged for 1 hour while maintaining the liquid temperature at 60°C. After aging, a 20% aqueous sodium hydroxide solution (manufactured by Takasugi Pharmaceutical Co., Ltd.) was added while increasing the temperature until the pH of the solution reached 7.0±0.2. The solution temperature after the addition of the aqueous sodium hydroxide solution was 70°C. Next, while maintaining the liquid temperature at 70°C, TiO ２ Al per 100 parts by mass ２ O ３ A sodium aluminate aqueous solution was added over 20 minutes so that the total weight of the mixture was 4 parts by mass, followed by aging for 20 minutes. After aging, a 20% sulfuric acid aqueous solution (manufactured by Ishihara Sangyo Kaisha) was added over 40 minutes to adjust the pH of the liquid to 5.5±0.2, followed by aging for 1 hour. After aging, the mixture was filtered through a Nutsche filter and washed with pure water until the filtrate conductivity reached 1500 Ω·cm or higher, and the solids were recovered. The recovered solids were dried at 150°C for 8 hours. 30 g of the resulting dried product was weighed, placed in a 50 mL crucible, and fired in an electric furnace at 450°C for 2 hours under atmospheric pressure. The firing was performed by increasing the temperature from room temperature to 450°C at a rate of 10°C / min, firing at 450°C for 2 hours, and then allowing it to cool naturally to room temperature. 10 g of the obtained fired product was weighed out and crushed for 10 minutes in a crusher (Ishikawa type stirring crusher, manufactured by Ishikawa Factory Co., Ltd.) to obtain Sample 2 of Production Example 2. The average primary particle diameter of Sample 2 was 17 nm.

[0226] [Production Example 3] In Production Example 2, the amount of sodium aluminate added was changed to TiO ２ Al per 100 parts by mass ２ O ３ was changed to 2.3 parts by mass, and before adding the sodium aluminate aqueous solution, TiO ２ SiO ２ Sample 3 of Production Example 3 was obtained in the same manner as in Production Example 2, except that an aqueous sodium silicate solution was added over 20 minutes so that the total amount of the sieving agent was 2.3 parts by mass.

[0227] [Manufacture example 4] TiO ２Titanium tetrachloride (TiO) to which citric acid (manufactured by Showa Kako Co., Ltd.) was added so that the citric acid concentration was 1 mol% per 1 mol of titanium tetrachloride. ２ An aqueous solution of titanium tetrachloride (200 g / L, calculated as a titanium tetrachloride solution, manufactured by Ishihara Sangyo Kaisha, Ltd.) was prepared. The temperature of the titanium tetrachloride aqueous solution was heated to 60°C and aged for 1 hour while maintaining the temperature at 60°C. After aging, a 20% aqueous solution of sodium hydroxide (manufactured by Takasugi Pharmaceutical Co., Ltd.) was added until the pH of the solution reached 7.0±0.2. The temperature of the solution during the addition of the sodium hydroxide solution was 70°C. After aging, a 20% aqueous solution of sulfuric acid (manufactured by Ishihara Sangyo Kaisha, Ltd.) was added over 40 minutes to adjust the pH of the solution to 5.5±0.2, followed by aging for 1 hour. After aging, the solution was filtered through a Nutsche filter and washed with pure water until the filtrate conductivity reached 1500 Ω·cm or higher, and the solid content was recovered. The recovered solid content was dried at 150°C for 8 hours. 30 g of the resulting dried product was weighed out, placed in a 50 mL crucible, and fired in an electric furnace at 450°C for 2 hours under atmospheric pressure. The firing was performed by increasing the temperature from room temperature to 450°C at a rate of 10°C / min, firing at 450°C for 2 hours, and then cooling to room temperature by natural cooling. 10 g of the fired product was weighed out and crushed for 10 minutes in a crusher (Ishikawa Mill Co., Ltd., Ishikawa type stirring crusher) to obtain Sample 4 of Production Example 4.

[0228] [Production Example 5] SnO ２ Hydrochloric acid (manufactured by Kanto Chemical Co., Ltd.) was added to a tin tetrachloride aqueous solution (manufactured by Nippon Chemical Industry Co., Ltd.) so that the concentration of TiO was 3 g / L and the concentration of hydrochloric acid was 8 g / L. ２ Titanium tetrachloride (TiO) to which citric acid (manufactured by Showa Kako Co., Ltd.) was added so that the citric acid concentration was 1 mol% per 1 mol of titanium tetrachloride. ２ The aqueous solution of tin tetrachloride containing hydrochloric acid was heated to 60°C, and TiO ２ SnO ２The titanium tetrachloride aqueous solution was added over 15 minutes so that the total weight of the titanium tetrachloride solution reached 5 parts by mass, and the solution was aged for 1 hour while maintaining the liquid temperature at 60°C. After aging, a 20% aqueous sodium hydroxide solution (manufactured by Takasugi Pharmaceutical Co., Ltd.) was added until the pH of the solution reached 7.0±0.2. The liquid temperature during the addition of the sodium hydroxide aqueous solution was 70°C. After aging, a 20% aqueous sulfuric acid solution (manufactured by Ishihara Sangyo Kaisha, Ltd.) was added over 40 minutes to adjust the pH of the solution to 5.5±0.2, and the solution was then aged for 1 hour. After aging, the solution was filtered using a Nutsche filter and washed with pure water until the filtrate conductivity reached 1500 Ω·cm or higher, and the solid content was recovered. The recovered solid content was dried at 150°C for 8 hours. 30 g of the resulting dried product was weighed out, placed in a 50 mL crucible, and fired in an electric furnace at 450°C for 2 hours under atmospheric pressure. The firing was performed by increasing the temperature from room temperature to 450°C at a rate of 10°C / min, firing at 450°C for 2 hours, and then cooling to room temperature by natural cooling. 10 g of the fired product was weighed out and crushed for 10 minutes in a crusher (Ishikawa Kogyo Co., Ltd., Ishikawa type stirring crusher) to obtain Sample 5 of Production Example 5.

[0229] [Production Example 6] TiO ２ Titanium tetrachloride (TiO) to which citric acid (manufactured by Showa Kako Co., Ltd.) was added so that the citric acid concentration was 1 mol% per 1 mol of titanium tetrachloride. ２ An aqueous solution of titanium tetrachloride (200 g / L, calculated as a titanium tetrachloride solution, manufactured by Ishihara Sangyo Kaisha) was prepared. The aqueous solution of titanium tetrachloride was heated to 60°C and aged for 1 hour while maintaining the liquid temperature at 60°C. After aging, a 20% aqueous solution of sodium hydroxide (manufactured by Takasugi Pharmaceutical Co., Ltd.) was added until the pH of the liquid reached 7.0±0.2. The liquid temperature when the aqueous solution of sodium hydroxide was added was 70°C. Next, while maintaining the liquid temperature at 70°C, TiO ２ Al per 100 parts by mass ２ O ３A sodium aluminate aqueous solution was added over 20 minutes so that the total weight of the mixture was 4 parts by mass, and then the mixture was aged for 20 minutes. After aging, a 20% sulfuric acid aqueous solution (manufactured by Ishihara Sangyo Kaisha) was added over 40 minutes to adjust the pH of the liquid to 5.5±0.2, and then the mixture was aged for 1 hour. After aging, the mixture was filtered through a Nutsche filter and washed with pure water until the filtrate conductivity reached 1500 Ω·cm or higher, and the solid matter was recovered. The recovered solid matter was dried at 150°C for 8 hours. 30 g of the resulting dried product was weighed, placed in a 50 mL crucible, and fired in an electric furnace at 450°C for 2 hours under atmospheric pressure. The firing was performed by increasing the temperature from room temperature to 450°C at a rate of 10°C / min, firing at 450°C for 2 hours, and then cooling to room temperature by natural cooling. 10 g of the obtained fired product was weighed out and crushed for 10 minutes in a crusher (Ishikawa type stirring crusher, manufactured by Ishikawa Kogyo Co., Ltd.) to obtain Sample 6 of Production Example 6.

[0230] [Production Example 7] SnO ２ Hydrochloric acid (manufactured by Kanto Chemical Co., Ltd.) was added to a tin tetrachloride aqueous solution (manufactured by Nippon Chemical Industry Co., Ltd.) so that the concentration of TiO was 3 g / L and the concentration of hydrochloric acid was 8 g / L, and the mixture was stirred to prepare a hydrochloric acid-containing tin tetrachloride aqueous solution. ２ Titanium tetrachloride (TiO) to which citric acid (manufactured by Showa Kako Co., Ltd.) was added so that the citric acid concentration was 1 mol% per 1 mol of titanium tetrachloride. ２ The aqueous solution of tin tetrachloride containing hydrochloric acid was heated to 60°C, and TiO ２ SnO ２ The titanium tetrachloride aqueous solution was added over 15 minutes so that the titanium tetrachloride content was 5 parts by mass, and the solution was aged for 1 hour while maintaining the liquid temperature at 60°C. After aging, a 20% aqueous sodium hydroxide solution (manufactured by Takasugi Pharmaceutical Co., Ltd.) was added while increasing the temperature until the pH of the solution reached 7.0±0.2. The solution temperature after the addition of the aqueous sodium hydroxide solution was 70°C. Next, while maintaining the liquid temperature at 70°C, TiO ２ Al per 100 parts by mass ２ O ３A sodium aluminate aqueous solution was added over 20 minutes so that the total weight of the solution was 4 parts by mass, and then the solution was aged for 20 minutes. After aging, a 20% sulfuric acid aqueous solution was added over 40 minutes to adjust the pH of the solution to 5.5±0.2, and the solution was then aged for 1 hour. Thereafter, while the solution temperature was maintained at 70°C, TiO ２ Co per 100 parts by mass ２ O ３ An aqueous solution of cobalt(II) sulfate heptahydrate (Kanto Chemical Co., Ltd.) was added all at once so that the total weight of the mixture was 0.1 parts by mass, and then aged for 20 minutes. After aging, the mixture was filtered through a Nutsche filter and washed with pure water until the filtrate conductivity reached 1500 Ω·cm or higher, and the solids were recovered. The recovered solids were dried at 150°C for 8 hours. 30 g of the resulting dried product was weighed out, placed in a 50 mL crucible, and fired in an electric furnace (Kyoei Electric Furnace Manufacturing Co., Ltd.) at 425°C for 2 hours under atmospheric pressure. The firing was performed by heating from room temperature to 425°C at a rate of 10°C / min, and after firing at 425°C for 2 hours, the mixture was naturally cooled to room temperature. 10 g of the resulting fired product was weighed out and pulverized for 10 minutes in a grinder (Ishikawa Mill Co., Ltd., Ishikawa-type stirring grinder) to obtain Sample 7 of Production Example 7. The average primary particle size of Sample 7 was 19 nm.

[0231] [Production Example 8] In Production Example 7, "Co ２ O ３ Sample 8 of Production Example 8 was obtained in the same manner as in Production Example 7, except that "cobalt (II) sulfate heptahydrate (manufactured by Kanto Chemical Co., Inc.)" was changed to "manganese (II) sulfate pentahydrate (manufactured by Kanto Chemical Co., Inc.)" so that MnO was 0.1 parts by mass. The average primary particle diameter of Sample 8 was 18 nm.

[0232] [Production Example 9] Sample 9 of Production Example 9 was obtained in the same manner as Production Example 2, except that the following step was added after firing at 450°C for 2 hours in Production Example 2. The average primary particle diameter of Sample 9 was 18 nm. 10 g of the sample fired at 450°C for 2 hours was crushed for 10 minutes using a crusher. Pure water was then added to the sample so that the concentration was 50 g / L, and the mixture was stirred to prepare a slurry. The slurry was heated to 60°C. After reaching 60°C, a 20 mass% aqueous solution of sodium hydroxide (manufactured by Takasugi Pharmaceutical Co., Ltd.) was added to the slurry until the pH reached 7.0±0.2. The sample was then fired at 450°C for 2 hours, and the average primary particle diameter of Sample 9 was 18 nm. 10 g of the sample fired at 450°C for 2 hours was crushed for 10 minutes using a crusher. Pure water was then added to the sample so that the concentration was 50 g / L, and the mixture was stirred to prepare a slurry. The slurry was heated to 60°C. After reaching 60°C, a 20 mass% aqueous solution of sodium hydroxide (manufactured by Takasugi Pharmaceutical Co., Ltd.) was added to the slurry until the pH reached 7.0±0.2. The sample was then fired at 450°C for 2 hours, and the average primary particle diameter of Sample 9 was 18 nm. ２ An aqueous solution of zirconium sulfate (manufactured by Kanto Chemical Co., Inc.) was added over 20 minutes so that the amount of TiO was 1 part by mass, and the solution was aged for 20 minutes while maintaining the liquid temperature at 60° C. After aging, the sample was fired at 450° C. for 2 hours, and the amount of TiO was 100 parts by mass. ２ An aqueous solution of titanium tetrachloride was added over 20 minutes so that the amount of titanium tetrachloride was 1 part by mass, and the solution was aged for 20 minutes while maintaining the liquid temperature at 60° C. After aging, the sample was calcined at 450° C. for 2 hours, and the amount of Al was ２ O ３ An aqueous sodium aluminate solution (manufactured by Kanto Chemical Co., Ltd.) was added over 20 minutes so that the total weight of the mixture was 1 part by mass, and the mixture was aged for 20 minutes while maintaining the liquid temperature at 60°C. After aging, the mixture was filtered through a Nutsche filter and washed with pure water until the filtrate conductivity reached 1500 Ω cm or more, and the solid content was recovered. The recovered solid content was dried at 150°C for 8 hours. 10 g of the resulting dried product was weighed out and pulverized for 10 minutes in a mortar (manufactured by Ishikawa Plant Co., Ltd., Ishikawa-type stirring mortar).

[0233] <Evaluation 1: Crystalline Form> Using the titanium dioxide microparticles of Production Examples 1 to 3 and Production Examples 7 to 9 as samples, X-ray diffraction spectra were measured using an X-ray diffractometer (Ultima IV, manufactured by Rigaku Corporation) under the following conditions: X-ray tube: CuKα, tube voltage: 40 kV, tube current: 40 mA, divergence slit: 1 / 2°, scattering slit: 8 mm, receiving slit: open, sampling width: 0.020°, and scanning speed: 10.00° / min. For reference, the X-ray diffraction spectrum of Production Example 2 is shown in FIG. 1. As shown in FIG. 1, peaks corresponding to rutile titanium dioxide were detected in the titanium dioxide microparticles of Production Example 2. However, it was found that peaks corresponding to tin oxide or aluminum oxide were not detected. This was also true for the samples of Production Examples 1, 3, and 7 to 9 (not shown).

[0234] Furthermore, using the XRD spectra of the titanium dioxide microparticles of Production Examples 1 to 3 and 7 to 9, the rutile content of the titanium dioxide microparticles of each Production Example was calculated according to the following formula, and the results are shown in Table 2. Rutile content (%) = (Hr / (Hr + Ha)) x 100, where Hr is the height of the maximum peak (2θ = 27.5° ± 0.5°) corresponding to rutile crystals in the X-ray diffraction spectrum, and Ha is the height of the maximum peak (2θ = 25.2° ± 0.5°) corresponding to anatase crystals in the X-ray diffraction spectrum.

[0235] <Evaluation 2: Elemental Analysis> The titanium dioxide fine particle powders of Production Examples 1 to 9 were pressure-molded into pellet-shaped measurement samples, which were then subjected to total elemental order (semi-quantitative) analysis using a fluorescent X-ray analyzer (ZSX Primus IV, manufactured by Rigaku Corporation). ２ , SnO ２ , Al ２ O ３ , SiO ２ The measurement results for each production example in Evaluation 2 are shown in Table 1.

[0236] <Evaluation 3: BET specific surface area> The titanium dioxide fine particle powders of Production Examples 1 to 9 were measured for BET specific surface area (m ) by a nitrogen adsorption method (BET method) using a flow-type automatic specific surface area measuring device (Macsorb HM model-1220, manufactured by Mountec). ２The desorption was carried out under nitrogen gas flow at room temperature, and the adsorption was carried out at 77 K. The measurement results are shown in Table 1.

[0237] <Evaluation 4: Average Particle Diameter of Primary Particles> The average particle diameter of primary particles for the titanium dioxide fine particle powders of Production Examples 1 to 3 and 7 to 9 was calculated as follows. The results are shown in Table 2. Images of the titanium dioxide fine particles were taken using a transmission electron microscope so that the number of primary particles per field of view was 300 to 700. The primary particle diameter, expressed as a circle-equivalent diameter (Heywood diameter), was measured for 300 or more primary particles in the image, and the median value in the number distribution of these particle diameters was calculated, which was used as the average particle diameter of the primary particles. Note that image analysis software Macview Version 4.0 (manufactured by Mountech Co., Ltd.) was used to calculate the average particle diameter.

[0238] <Evaluation 5: Average Aspect Ratio of Primary Particles> The aspect ratios of the titanium dioxide microparticles of Production Examples 1 to 3 and 7 to 9 were calculated as follows. The results are shown in Table 2. Images of the titanium dioxide microparticles were taken using a transmission electron microscope so that the number of primary particles per field of view was 300 to 700. For 300 or more primary particles in the images, the major axis (the length of the long side of the circumscribing rectangle with the smallest area) and minor axis (the length of the short side of the circumscribing rectangle with the smallest area) of each primary particle were measured using image analysis software Macview Version 4.0 (manufactured by Mountech Co., Ltd.). The major axis was divided by the minor axis to calculate the aspect ratio of each of the 300 or more primary particles. The average of the calculated aspect ratios was then calculated.

[0239]

[0240]

[0241] Example 1: 12.8 g of Sample 1 (titanium dioxide microparticles), 1.92 g of 3-methacryloxypropyltriethoxysilane KBM-503 (Shin-Etsu Silicones Co., Ltd.) as a silane coupling agent, 0.384 g of Solsperse (registered trademark) 20000 (Lubrizol, amine value 32 mg KOH / g) as an amino-based dispersant having a basic adsorption group, 24.896 g of propylene glycol monomethyl ether (PGME) as an organic solvent, and 100 g of 0.05 mm zirconia beads were placed in a 70 mL mayonnaise bottle and wet-dispersed for 4 hours using a paint shaker (Red Devil Model 5410). The zirconia beads were removed from the resulting dispersion, which was then centrifuged at 2400 G for 30 minutes to recover the supernatant, yielding an organic solvent dispersion of Example 1. The mass ratio of the amine-based dispersant to the silane coupling agent in this organic solvent dispersion was 20 mass %. The silane coupling agent and the amine-based dispersant used relative to the titanium dioxide fine particles were 15 mass % and 3 mass %, respectively, for a total amount of 18 mass %.

[0242] Example 2 An organic solvent dispersion of Example 2 was obtained in the same manner as in Example 1, except that the titanium dioxide fine particles in Example 1 were changed to Sample 2.

[0243] (Example 3) An organic solvent dispersion of Example 3 was obtained in the same manner as in Example 1, except that the amount of Solsperse 20000 used in Example 1 was changed to 0.640 g and the amount of PGME used in Example 1 was changed to 24.640 g. The mass ratio of the amine-based dispersant to the silane coupling agent in this organic solvent dispersion was 33 mass%. The silane coupling agent and the amine-based dispersant used relative to the titanium dioxide fine particles were 15 mass% and 5 mass%, respectively, and the total amount of both was 20 mass%.

[0244] Example 4 An organic solvent dispersion of Example 4 was obtained in the same manner as in Example 1, except that the titanium dioxide fine particles in Example 1 were changed to Sample 3.

[0245] Example 5: 12.8 g of Sample 2 (titanium dioxide microparticles), 1.92 g of silane coupling agent 3-methacryloxypropyltriethoxysilane KBM-503 (Shin-Etsu Silicones Co., Ltd.), 0.435 g of amine-based dispersant Solsperse (registered trademark) 20000 (Lubrizol, amine value 32 mgKOH / g), 24.840 g of organic solvent propylene glycol monomethyl ether acetate (PGMEA), and 100 g of 0.05 mm zirconia beads were placed in a 70 mL mayonnaise bottle and wet-dispersed for 4 hours using a paint shaker (Red Devil Model 5410). The zirconia beads were removed from the resulting dispersion, which was then centrifuged at 2400 G for 30 minutes to recover the supernatant, yielding an organic solvent dispersion of Example 5. The mass ratio of the amine-based dispersant to the silane coupling agent in this organic solvent dispersion was 22.6 mass%. The silane coupling agent and the amine-based dispersant used relative to the titanium dioxide fine particles were 15 mass% and 3.4 mass%, respectively, for a total amount of 18.4 mass%.

[0246] Example 6 An organic solvent dispersion of Example 6 was obtained in the same manner as in Example 5, except that the organic solvent was changed to PGME and the titanium dioxide fine particles were changed to Sample 7.

[0247] Example 7 An organic solvent dispersion of Example 7 was obtained in the same manner as in Example 6, except that the titanium dioxide fine particles in Example 6 were changed to Sample 8.

[0248] Example 8 An organic solvent dispersion of Example 8 was obtained in the same manner as in Example 6, except that the titanium dioxide fine particles in Example 6 were changed to Sample 9.

[0249] Comparative Example 1 In Comparative Example 1, an organic solvent dispersion was obtained in the same manner as in Example 1, except that the titanium dioxide fine particles in Example 1 were changed to Sample 4.

[0250] Comparative Example 2 In Comparative Example 2, an organic solvent dispersion was obtained in the same manner as in Example 1, except that the titanium dioxide fine particles in Example 1 were changed to Sample 5.

[0251] Comparative Example 3 In Comparative Example 3, an organic solvent dispersion was obtained in the same manner as in Example 1, except that the titanium dioxide fine particles in Example 1 were changed to Sample 6.

[0252] (Comparative Example 4) An organic solvent dispersion of Comparative Example 4 was obtained in the same manner as in Example 2, except that the amine-based dispersant was not used and the amount of silane coupling agent used was changed to 2.304 g. The mass ratio of the amine-based dispersant in this organic solvent dispersion to the silane coupling agent was 0 mass%. The silane coupling agent and amine-based dispersant used relative to the titanium dioxide fine particles were 18 mass% and 0 mass%, respectively, and the total amount of both was 18 mass%.

[0253] <Evaluation 6: Dispersion Yield> Each of the organic solvent dispersions of Examples 1 to 8 and Comparative Examples 1 to 4 was centrifuged at 2400 G for 30 minutes, and the supernatant was recovered. The supernatant was dried at 150°C for at least 1 hour or more until there was no weight loss from the supernatant, and the resulting solid content was measured (specifically, the weight of the resulting solid content was measured, and the solid content concentration in the supernatant was calculated). The dispersion yield was calculated by dividing the amount (specifically, the solid content concentration of the supernatant) by the solid content concentration of the organic solvent dispersion of Examples 1 to 8 and Comparative Examples 1 to 4 at the time of preparation (i.e., before centrifugation).

[0254] <Evaluation 7: Transmittance of Dispersion> The supernatant of the organic solvent dispersion after centrifugation was measured for average transmittance in the range of 380 nm to 780 nm using a spectrophotometer (V-770, manufactured by JASCO Corporation, quartz cell thickness 10 mm) with the titanium dioxide fine particle concentration of the dispersion adjusted to 12 g / L. The titanium dioxide fine particle concentration of the dispersion was determined from the residue after heating at 800°C. The results are shown in Table 3.

[0255] <Evaluation 8: D50, D90> The volume-based D50 and D90 of the supernatant of the organic solvent dispersion after centrifugation were measured using a dynamic light scattering particle size distribution analyzer (NANOTRAC (registered trademark) WAVE II EX150, manufactured by Microtrackbell) or the like under the following conditions.

[0256] Measurement conditions (when the solvent is PGME): (1) Refractive index of solvent (PGME): 1.4, viscosity 1.75 (25°C) - 1.55 (30°C); (2) Particle refractive index: 2.55; (3) Particle density: 4.2 g / cm ３ and (4) loading index: 0.1 to 0.3.

[0257] Measurement conditions (when the solvent is PGMEA): (1) Refractive index of solvent (PGMEA): 1.4, Viscosity: 1.098 (20°C) - 0.948 (30°C); (2) Particle refractive index: 2.55; (3) Particle density: 4.2 g / cm ３ (4) Loading index: 0.1-0.3.

[0258]

[0259] The titanium dioxide fine particles contained in the organic solvent dispersions of Examples 1 to 3 and Example 5 all contain a tin component and an aluminum component, and the organic solvent dispersions also contain a silane coupling agent and a dispersant having a basic adsorptive group. The organic solvent dispersions of Examples 1 to 3 and Example 5 have a dispersion yield of 50% or more and a transmittance of 25% or more, and are therefore excellent in dispersion stability.

[0260] It can also be seen that the organic solvent dispersion of Example 4, which uses titanium dioxide microparticles containing silicon components in addition to tin and aluminum components, has the same dispersion yield and transparency as Examples 1 to 3 and Example 5.

[0261] Furthermore, it can be seen that the organic solvent dispersions of Examples 6 and 7, which use titanium dioxide microparticles containing a cobalt component or a manganese component in addition to a tin component and an aluminum component, also have dispersion yields and transparency equivalent to those of Examples 1 to 3 and Example 5.

[0262] It can also be seen that the organic solvent dispersion of Example 8, which uses titanium dioxide microparticles containing a tin component and an aluminum component and having an inorganic compound coating on the surface, has a dispersion yield and transparency equivalent to those of Examples 1 to 3 and Example 5.

[0263] On the other hand, the organic solvent dispersions of Comparative Examples 1 to 3, which used titanium dioxide microparticles that did not contain a tin component and / or an aluminum component, had either a dispersion yield or a transmittance of less than 50% or less than 25%, or were gelled, and therefore did not have sufficient dispersion stability.

[0264] Furthermore, the organic solvent dispersion of Comparative Example 4, which uses titanium dioxide microparticles containing tin and aluminum components but does not contain a dispersant having a basic adsorption group, has a transmittance of less than 25%, and therefore does not have sufficient dispersion stability.

[0265] Example 9 [Preparation of Coating Composition] In the organic solvent dispersion described in Example 1, 14.3 parts by mass each of Light Acrylate (registered trademark) POB-A (manufactured by Kyoeisha Chemical Co., Ltd., acrylic monomer) and Aronix (registered trademark) M-309 (manufactured by Toagosei Co., Ltd., trimethylolpropane triacrylate) as ultraviolet curable resins, and 1.4 parts by mass of Omnirad (registered trademark)-907 (manufactured by IGM RESINS B.V.) as a curing polymerization initiator were mixed with 70 parts by mass of the solid content to obtain a coating composition. The solid content of the organic solvent dispersion was determined from the heating residue at 150°C.

[0266] [Preparation of Coating Film] The above coating composition was applied to a cleaned glass plate by spin coating (1000 rpm x 8 seconds), dried at 90°C for 3 minutes, and then exposed to a high-pressure mercury lamp at 3 J / cm ２ The coating film of Example 9 was obtained by irradiating the sample with an integrated light amount of 10 ...

[0267] Example 10 A coating film of Example 10 was obtained in the same manner as in Example 9, except that the organic solvent dispersion described in Example 2 was used.

[0268] Example 11 A coating film of Example 11 was obtained in the same manner as in Example 9, except that the organic solvent dispersion described in Example 4 was used.

[0269] Example 12 A coating film of Example 12 was obtained in the same manner as in Example 9, except that the organic solvent dispersion described in Example 5 was used.

[0270] Example 13 A coating film of Example 13 was obtained in the same manner as in Example 9, except that the organic solvent dispersion described in Example 6 was used.

[0271] Example 14 A coating film of Example 14 was obtained in the same manner as in Example 9, except that the organic solvent dispersion described in Example 7 was used.

[0272] Example 15 A coating film of Example 15 was obtained in the same manner as in Example 9, except that the organic solvent dispersion described in Example 8 was used.

[0273] <Evaluation 7: Haze and refractive index of coating film> The haze of the coating films obtained in Examples 9 to 15 was measured in accordance with JIS K 7136 using a haze meter (COH-7700 (manufactured by Nippon Denshoku Industries Co., Ltd.)).

[0274] The film thickness and refractive index of the coating film at a measurement wavelength of 589 nm were measured using a visible spectroscopic ellipsometer (Smart SE (manufactured by Horiba, Ltd.)). The results are shown in Table 4.

[0275]

[0276] As can be seen from Table 4, the haze of all the coating films obtained in Examples 9 to 15 was 5% or less and the refractive index was 1.60 or more. These results show that the obtained coating films were highly transparent and had a high refractive index.

[0277] The organic solvent dispersion of the present invention containing titanium dioxide fine particles has excellent dispersion stability. The organic solvent dispersion of the present invention has high yield and high transparency. Furthermore, by using the organic solvent dispersion of the present invention, a coating film having high transparency and a high refractive index can be formed.

Claims

1. An organic solvent dispersion of titanium dioxide microparticles comprising: titanium dioxide microparticles in which titanium components, tin components, and aluminum components are detected by X-ray fluorescence analysis, and in which X-ray diffraction peaks attributable to rutile titanium dioxide are observed by powder X-ray diffraction measurement, but no X-ray diffraction peaks attributable to tin components and aluminum components are observed; an organic solvent; a silane coupling agent; and a dispersant having a basic adsorption group.

2. An organic solvent dispersion of titanium dioxide microparticles comprising: titanium dioxide microparticles in which titanium components, tin components, and aluminum components are detected by X-ray fluorescence analysis, and in which only X-ray diffraction peaks attributable to rutile titanium dioxide are observed by powder X-ray diffraction measurement, with no X-ray diffraction peaks attributable to tin components and aluminum components being observed; an organic solvent; a silane coupling agent; and a dispersant having a basic adsorption group.

3. The organic solvent dispersion of titanium dioxide particles according to claim 1 or 2, wherein the titanium dioxide particles contain titanium dioxide particles in which the tin component and the aluminum component are dissolved in a solid solution.

4. The total amount of the tin component and the aluminum component relative to the amount of the titanium component in the titanium dioxide fine particles is such that the amount of the titanium component is reduced by 100%. ２ amount 、 The amount of the tin component is SnO ２ The amount of the aluminum component is Al ２ O ３ In terms of quantity, [(SnO ２ Amount + Al ２ O ３ amount) / TiO ２ 3. The organic solvent dispersion of titanium dioxide fine particles according to claim 1, wherein the organic solvent dispersion has a content of 0.6 mass % or more and 30 mass % or less when expressed in terms of a mass ratio of the amount of the titanium dioxide fine particles to the amount of the organic solvent.

5. The amount of the tin component relative to the amount of the aluminum component is such that the amount of the aluminum component is Al ２ O ３ and the amount of the tin component is SnO ２ In terms of quantity, [SnO ２ Amount / Al ２ O ３ 3. The organic solvent dispersion of titanium dioxide fine particles according to claim 1, wherein the organic solvent dispersion has a content of 0.01 mass % or more and 40 mass % or less when expressed in terms of a mass ratio of [amount of titanium dioxide] to [amount of titanium dioxide].

6. An organic solvent dispersion of titanium dioxide microparticles as described in claim 1 or 2, wherein the mass ratio of the dispersant having a basic adsorption group to the silane coupling agent is 15 mass % or more and 75 mass % or less.

7. An organic solvent dispersion of titanium dioxide microparticles as described in claim 1 or 2, comprising titanium dioxide microparticles in which one or more components selected from the group consisting of silicon components, cobalt components and manganese components are further detected by fluorescent X-ray analysis measurement, and no X-ray diffraction peaks derived from one or more components selected from the group consisting of silicon components, cobalt components and manganese components are observed by powder X-ray diffraction measurement.

8. An organic solvent dispersion of titanium dioxide fine particles according to claim 1 or 2, wherein the titanium dioxide fine particles contain titanium dioxide fine particles having one or more components selected from the group consisting of silicon components, cobalt components and manganese components dissolved therein.

9. The organic solvent dispersion of titanium dioxide fine particles according to claim 1 or 2, wherein the surfaces of the titanium dioxide fine particles are coated with an inorganic compound.

10. A coating composition comprising an organic solvent dispersion of the titanium dioxide fine particles according to claim 1 or 2, and a binder resin.

11. A coating film comprising an organic solvent dispersion of titanium dioxide fine particles according to claim 1 or 2 and a binder resin.

12. A composition for nanoimprints comprising an organic solvent dispersion of the titanium dioxide fine particles according to claim 1 or 2, and a binder resin.

13. A method for producing an organic solvent dispersion of titanium dioxide microparticles, comprising a step of dispersing titanium dioxide microparticles in an organic solvent, in which titanium components, tin components, and aluminum components are detected by X-ray fluorescence analysis, and in which X-ray diffraction peaks attributable to rutile titanium dioxide are observed by powder X-ray diffraction measurement, but no X-ray diffraction peaks attributable to tin components and aluminum components are observed, a silane coupling agent, and a dispersant having a basic adsorption group.

14. A method for producing an organic solvent dispersion of titanium dioxide microparticles, comprising a step of dispersing titanium dioxide microparticles in an organic solvent, in which titanium components, tin components, and aluminum components are detected by X-ray fluorescence analysis, and in which only X-ray diffraction peaks attributable to rutile titanium dioxide are observed by powder X-ray diffraction measurement, with no X-ray diffraction peaks attributable to tin components and aluminum components being observed, a silane coupling agent, and a dispersant having a basic adsorption group.

15. A method for producing an organic solvent dispersion of titanium dioxide fine particles according to claim 13 or 14, further comprising a step of centrifuging the organic solvent dispersion.

16. A method for producing an organic solvent dispersion of titanium dioxide fine particles according to claim 13 or 14, wherein the titanium dioxide fine particles are produced by the following steps: step (1): a step of hydrolyzing a mixture of titanium (oxy)chloride and a tin compound, or a step of hydrolyzing titanium (oxy)chloride in the presence of core particles obtained by hydrolyzing a tin compound; step (2): a step of mixing the product after the hydrolysis with an aluminum compound; and step (3): a step including baking the mixture of the product after the hydrolysis with an aluminum compound at a temperature of 250°C or higher and 1000°C or lower.

17. A method for producing an organic solvent dispersion of titanium dioxide fine particles as described in claim 16, wherein the step (1) is a step of hydrolyzing a mixture of titanium (oxy)chloride, a tin compound, and a carboxylic acid or a salt thereof, or a step of adding titanium (oxy)chloride and a carboxylic acid or a salt thereof in the presence of core particles obtained by hydrolysis of a tin compound, and hydrolyzing the titanium (oxy)chloride.

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