Method for producing zirconia-coated titanium oxide fine particles, zirconia-coated titanium oxide fine particles, and use thereof

Abstract

[Problem] To provide titanium oxide-based microparticles, etc., said microparticles maintaining a high refractive index and yet having a suppressed photocatalytic activity. [Solution] A method for producing a dispersion of zirconia-coated titanium oxide microparticles, said method comprising: (1) a step for preparing a dispersion (1) of titanium oxide microparticles; (2) a step for adding, to the dispersion (1), 1-50 parts by mass, in terms of the mass of ZrO2 per 100 parts by mass of the titanium oxide microparticles, of an aqueous peroxidic zirconic acid solution and then aging reacted microparticles (2a), which have been obtained by the reaction between the titanium oxide microparticles and the peroxidic zirconic acid, to thereby give a dispersion (2) of a zirconia-coated titanium oxide microparticle precursor (2b); and (3) a step for adjusting the solid component concentration of the dispersion (2) to 0.01-10 mass% followed by a hydrothermal treatment.

Description

Technical Field

[0001] The present invention relates to a method for producing a titanium oxide fine particle dispersion liquid and the like, and more particularly to a method for producing a titanium oxide fine particle dispersion liquid that is preferably used as a material for a coating liquid for forming a coating film on a plastic substrate and the like.

Background Art

[0002] Titanium oxide fine particles are suitably used as a material for a coating liquid for forming a coating film on an optical substrate such as a plastic lens because they have a high refractive index. In particular, rutile-type crystalline titanium oxide fine particles have lower photocatalytic activity than anatase-type ones, so that it is possible to suppress a decrease in adhesion between a substrate and a coating film due to decomposition of an organosilicon compound or a resin component of a film-forming component. As improvement methods, there are a) a method of supporting a metal on titanium oxide, b) a method of increasing the crystallinity of titanium oxide, and c) a method of providing a coating layer.

[0003] As an example of a method for producing a rutile-type crystalline titanium oxide fine particle dispersion liquid, for example, Patent Document 1 describes that hydrogen peroxide is added to a gel or sol of hydrated titanium oxide to dissolve the hydrated titanium oxide, and the rutile-type titanium oxide fine particle dispersion liquid is obtained by heating the solution in the coexistence of a tin compound in an amount of TiO2 / SnO2 = 1.5 to 14 (weight ratio). It is also described that the sol obtained by further coexisting a silicon compound in a mixed aqueous solution of an aqueous titanic acid solution and a tin compound and heating and hydrolyzing it increases the dispersion stability.

[0004] a) As a method of supporting a metal on titanium oxide, Patent Documents 2 and 3 disclose that, in order to provide a coating liquid for forming a hard coat film having a high refractive index, excellent transparency, weather resistance, and adhesion to a substrate, the coating liquid for film formation contains composite oxide fine particles composed of a titanium oxide component and an iron oxide component in a range where the weight ratio of Fe2O3 / TiO2 is 0.0005 or more and less than 0.005. The film obtained by using the anatase-type titanium oxide and iron oxide composite oxide fine particles prepared by the production method disclosed in Patent Document 3 as a coating liquid for forming a coating film is excellent in weather resistance because the photocatalytic activity of the composite oxide fine particles is suppressed.

[0005] b) As a method of increasing the crystallinity of titanium oxide, Patent Documents 4, 5, and 6 describe particles obtained by firing core particles and then forming a shell layer, or particles obtained by firing core-shell type particles, and in each case, an improvement in weather resistance compared to the unfired product is clearly shown.

[0006] c) As a method of applying a coating layer, Patent Documents 7, 8, and 9 disclose core-shell type fine particles coated with a composite oxide composed of silicon, zirconium, antimony, or aluminum oxide using rutile-type titanium oxide fine particles or iron-containing rutile-type titanium oxide fine particles as nuclei. By adopting such a configuration, the photocatalytic activity of the rutile-type titanium oxide fine particles is suppressed, so the film obtained by using the core-shell fine particles as a coating liquid for forming a coating film is excellent in weather resistance.

[0007] On the other hand, there are those in which metal oxide fine particles containing titanium are used as core particles and the surface is treated with a hydrate and / or oxide of one kind of metal element such as zirconium or antimony. Patent Document 10 discloses surface-treated particles treated with a hydrate and / or oxide of zirconium. It is described that by using these particles, the dispersion stability and transparency are excellent, and the coating film formed from the coating liquid containing these particles has improved weather resistance and light resistance.

[0008] Furthermore, Patent Document 11 describes particles coated with antimony oxide.

Prior Art Documents

Patent Documents

[0009]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Patent Document 5

Patent Document 6

Patent Document 7

Patent Document 8

Patent Document 9

Patent Document 10

Patent Document 11

Summary of the Invention

Problems to be Solved by the Invention

[0010] According to the findings of the present inventors, there has been room for further improvement in conventional titanium oxide fine particles from the viewpoint of exhibiting excellent weather resistance and light resistance while maintaining a high refractive index.

[0011] Therefore, an object of the present invention is to provide titanium oxide-based fine particles in which photocatalytic activity is suppressed (that is, excellent in weather resistance and light resistance) while maintaining a high refractive index, a dispersion thereof, and a method for producing the same.

Means for Solving the Problems

[0012] As a result of extensive research, the present inventors have found that the above-mentioned problems can be solved by using titanium oxide fine particles as core particles and densely coating these with zirconia, and have thus completed the present invention.

[0013] [1] (1) preparing a dispersion (1) of titanium oxide fine particles that satisfies the following requirement (a): (2) adding 1 to 50 parts by mass of an aqueous solution of zirconia peroxide, calculated as the mass of ZrO2, per 100 parts by mass of the titanium oxide fine particles to the dispersion (1), and then aging the reaction fine particles (2a) obtained by the reaction of the titanium oxide fine particles with the zirconia peroxide to obtain a dispersion (2) of zirconia-coated titanium oxide fine particle precursor (2b); (3) adjusting the solid content of the dispersion (2) to 0.01 to 10% by mass, and then subjecting the dispersion (2) to a hydrothermal treatment to obtain a dispersion of zirconia-coated titanium oxide fine particles; A method for producing a dispersion of zirconia-coated titanium oxide fine particles, comprising: Requirement (a): The titanium oxide microparticles contain 60% or more by mass of Ti, calculated as the mass of TiO2, and further contain at least one metal element selected from the group consisting of Al, Zr, Sb, Zn, Ni, Fe, Ba, Mg, Sn, Si, and V.

[0014] [2] The method for producing a dispersion of zirconia-coated titanium oxide microparticles according to [1] above, wherein, in the step (2), the average particle size and haze (%) of the reactive microparticles (2a) at the completion of the addition of the aqueous zirconium peroxide solution are respectively designated as D2 and Hz2, and the average particle size and haze (%) of the precursor (2b) are respectively designated as D3 and Hz3, and D3 / D2 is 1.1 to 3.0 and Hz3 / Hz2 is 0.8 to 1.2.

[0015] [3] A dispersion of zirconia-coated titanium oxide fine particles produced by the method of [1] or [2] above. [4] Zirconia-coated titanium oxide fine particles isolated from the zirconia-coated titanium oxide fine particle dispersion of [3].

[0016] [5] Zirconia-coated titanium oxide fine particles having titanium oxide fine particles satisfying the following requirement (a) and a zirconia coating layer satisfying the following requirement (b) that coats the titanium oxide fine particles, satisfying the following requirement (c), and having an average particle diameter of 3 to 50 nm. Requirement (a): The titanium oxide fine particles contain 60% by mass or more of Ti in terms of the mass of TiO2, and further contain at least one metal element selected from the group consisting of Al, Zr, Sb, Zn, Ni, Fe, Ba, Mg, Sn, Si, and V. Requirement (b): The amount of the zirconia coating layer is 1 to 50 parts by mass in terms of the mass of ZrO2 with respect to 100 parts by mass of the titanium oxide fine particles. Requirement (c): When the average particle diameter and the fading rate of the titanium oxide fine particles are D1 and PA1, respectively, and the average particle diameter and the fading rate of the zirconia-coated titanium oxide fine particles are D4 and PA4, respectively, D4 / D1 is 0.8 to 1.2, and PA4 / PA1 is 0.4 or less.

[0017] [6] The zirconia-coated titanium oxide fine particles of [5], wherein the titanium oxide fine particles contain Ti and Sn in a ratio of 3 to 16 in terms of the mass ratio of TiO2 / SnO2.

[0018] [7] A dispersion of the zirconia-coated titanium oxide fine particles of [5] or [6]. [8] A paint composition containing the zirconia-coated titanium oxide fine particles of any one of [4] to [6] and a matrix component.

[0019] [9] A coating film obtained by curing the paint composition of [8].

[10] A substrate with a coating film, having a substrate and the coating film of [9] provided on the surface of the substrate.

Advantages of the Invention

[0020] According to the production method of the present invention, titanium oxide-based fine particles (zirconia-coated titanium oxide fine particles) that maintain a high refractive index while suppressing photocatalytic activity (that is, excellent in weather resistance and light resistance), a dispersion thereof, a coating composition containing the fine particles, and production methods thereof can be provided, as compared with conventional titanium oxide-based fine particles.

[0021] In addition, the zirconia-coated titanium oxide fine particles of the present invention maintain a high refractive index and are also excellent in weather resistance and light resistance (photocatalytic activity is suppressed). Furthermore, a coated substrate provided with a hard coat layer or an ultraviolet shielding coat layer having a higher refractive index and suppressed photocatalytic activity can be provided from the coating composition.

Mode for Carrying Out the Invention

[0022] Hereinafter, the present invention will be specifically described. [Zirconia-coated titanium oxide fine particles] The zirconia-coated titanium oxide fine particles according to the present invention have titanium oxide fine particles satisfying the following requirement (a) and a zirconia coating layer satisfying the following requirement (b) that coats the titanium oxide fine particles, satisfy the following requirement (c), and have an average particle diameter of 3 to 50 nm zirconia-coated titanium oxide fine particles (hereinafter also referred to as "zirconia-coated titanium oxide fine particles (I)"). Requirement (a): The titanium oxide fine particles contain 60% by mass or more of Ti in terms of the mass of TiO2, and further contain at least one metal element selected from the group consisting of Al, Zr, Sb, Zn, Ni, Fe, Ba, Mg, Sn, Si, and V. Requirement (b): The amount of the zirconia coating layer is 1 to 50 parts by mass in terms of the mass of ZrO2 with respect to 100 parts by mass of the titanium oxide fine particles. Requirement (c): Let the average particle diameter and fading rate of the titanium oxide fine particles be D1 and PA1 respectively, and the average particle diameter and fading rate of the zirconia-coated titanium oxide fine particles be D4 and PA4 respectively. Then, D4 / D1 is 0.8 to 1.2, and PA4 / PA1 is 0.4 or less.

[0023] 《Nuclear particles》 The proportion of Ti (in terms of TiO2 conversion) in the titanium oxide fine particles is preferably 60% by mass or more, more preferably 65% by mass.

[0024] The crystal structure of the titanium oxide contained in the titanium oxide fine particles may be either anatase type or rutile type, but from the viewpoint of photoactivity, a rutile type structure is preferred. Examples of preferred embodiments of the titanium oxide fine particles include the following titanium oxide fine particles (i) to (iv) (some of these may overlap).

[0025] Titanium oxide fine particles (i) contain rutile type titanium oxide containing Sn, and the proportions of Ti and Sn are preferably in the range of 3 to 16, more preferably 4 to 13, in terms of the mass ratio of TiO2 / SnO2, and are titanium oxide-based composite oxide fine particles.

[0026] Titanium oxide fine particles (ii) contain Sb at 25% by mass or less in terms of Sb2O5 conversion, preferably 0.1 to 10% by mass, Fe at 10% by mass or less in terms of Fe2O3 conversion, preferably 0.1 to 5% by mass, Ni at 3% by mass or less in the core particles in terms of NiO conversion, preferably 0.001 to 1% by mass, and Zr at 15% or less in the particles in terms of ZrO2 conversion, preferably 0.5 to 10% by mass, and are titanium oxide-based composite oxide particles.

[0027] The titanium oxide fine particles (iii) are crystalline titanium oxide-based composite oxide particles containing nickel and zirconium, having no significant coloring, and capable of suppressing photoactivity. The content of nickel in the titanium oxide fine particles (iii) is preferably 0.001 to 1% by mass, more preferably 0.01 to 0.08% by mass in terms of NiO, and the content of zirconium is preferably 0.5 to 10% by mass, more preferably 1 to 8% by mass in terms of ZrO2.

[0028] The titanium oxide fine particles (iv) are crystalline titanium oxide-based composite oxide particles containing iron and antimony, having relatively low coloring, and capable of strongly suppressing photoactivity. The content of iron in the titanium oxide fine particles (iv) is preferably 0.1 to 5% by mass, more preferably 0.2 to 4% by mass in terms of Fe2O3, and the content of antimony is preferably 0.1 to 10% by mass, more preferably 0.4 to 8% by mass in terms of Sb2O5. Further, the ratio of iron and antimony, in terms of the mass ratio of the oxides (Sb2O5 / Fe2O3), is preferably 0.5 to 10, more preferably 1 to 5, and still more preferably 2 to 2.5. It is considered that a part of the titanium sites of titanium oxide constituting the titanium oxide fine particles is substituted by a metal element other than titanium described above.

[0029] 《Coating layer》 The zirconia-coated titanium oxide fine particles according to the present invention are core-shell type fine particles in which the titanium fine particles are coated with a layer made of zirconia (hereinafter also referred to as "coating layer"). The coating layer can further reduce the photoactivity of the titanium oxide fine particles as the core particles.

[0030] The amount of zirconium (in terms of ZrO2 conversion amount) contained in the coating layer of the zirconia-coated titanium oxide fine particles is preferably 1 to 50 parts by mass, preferably 2 to 40 parts by mass with respect to 100 parts by mass of the titanium oxide fine particles as the core particles. This amount can be adjusted by the charged amounts of the raw materials of the titanium oxide fine particles and the coating layer.

[0031] The coating layer contains zirconia as a main component. When components other than zirconia are contained in the coating layer, the amount (in terms of oxide conversion amount) is preferably less than 50% by mass, more preferably 10% by mass or less, based on the amount of the coating layer (100% by mass). This amount can be adjusted by the charged amount of the raw material of the coating layer.

[0032] 《Zirconia-coated titanium oxide fine particles》 The average particle diameter of the zirconia-coated titanium oxide fine particles of the present invention is 3 to 50 nm, preferably 6 to 45 nm. In the present invention, the value of the average particle diameter of various fine particles is obtained by diluting the fine particles with a solvent (this solvent is water unless otherwise specified) so that the solid content concentration becomes 0.1% by mass, measuring by the dynamic light scattering method, and performing cumulant analysis.

[0033] Also, when the average particle diameter and the fading rate of the titanium oxide fine particles are D1 and PA1, respectively, and the average particle diameter and the fading rate of the zirconia-coated titanium oxide fine particles are D4 and PA4, respectively, D4 / D1 is 0.8 to 1.2, preferably 0.9 to 1.1, and PA4 / PA1 is 0.4 or less. The lower limit value of PA4 / PA1 may be 0.001, for example. The fact that D4 / D1 and PA4 / PA1 are within the above ranges means that a dense zirconia coating layer is formed on the surface of the titanium oxide fine particles. The fading rate is the rate of change per unit time of the absorbance derived from the dye under ultraviolet irradiation in a system in which titanium oxide fine particles and the dye are mixed, and is measured by the following method.

[0034] <Measurement method of fading rate> To an aqueous dispersion of the particulate matter to be measured in an amount corresponding to 0.05 g in terms of solid content, an appropriate solvent is added as appropriate so that the water / methanol = 1 / 1 (mass ratio) and the solid content concentration is 0.5 mass%. Next, the obtained dispersion and a glycerin solution of sunset yellow FCF dye with a solid content concentration of 0.02 mass% are mixed so that the mass ratio (dispersion mass / glycerin solution mass) is 1 / 3 to prepare a sample, which is placed in a quartz cell with a depth of 1 mm, a width of 1 cm, and a height of 5 cm. Next, using an ultraviolet lamp with a wavelength range of I-line (wavelength 365 nm), ultraviolet light is irradiated from a distance of 5.5 cm to the surface of the quartz cell with a width of 1 cm × height of 5 cm at an intensity of 0.4 mW / cm 2 (in terms of wavelength 365 nm).

[0035] The absorbance (A0) of the sample before ultraviolet irradiation at a wavelength of 490 nm and the absorbance (A n ) after n hours of ultraviolet irradiation were measured with an ultraviolet-visible spectrophotometer, and the fading rate of the dye was calculated from the following formula. Fading change rate = (A n - A0) / A0 × 100 (%) PA (fading rate) = fading change rate / UV irradiation time (% / h)

[0036] The irradiation time of ultraviolet light is adjusted as follows according to the fading rate. (1) When the fading rate is 30% / h or more, the time until the fading change rate reaches 70 - 90% (2) When the fading rate is 3 or more and less than 30% / h, 3 hours (3) When the fading rate is less than 3% / h, 20 hours

[0037] The values of the average particle diameter and the fading rate are, more specifically, those measured by the method adopted in the examples described later. The zirconia-coated titanium oxide fine particles of the present invention have suppressed photocatalytic activity while maintaining a high refractive index as compared with conventional titanium oxide fine particles.[[ID=३१]] In addition, the zirconia-coated titanium oxide fine particles have high shape uniformity. High shape uniformity of the fine particles can be confirmed by observing the fine particles with a scanning electron microscope (SEM). Therefore, the zirconia-coated titanium oxide fine particles are also excellent in transparency.

[0038] [Dispersion of zirconia-coated titanium oxide fine particles] The zirconia-coated titanium oxide fine particle dispersion according to the present invention is a dispersion of the zirconia-coated titanium oxide fine particles according to the present invention, and may be any of an aqueous dispersion, a dispersion of water and an organic solvent, or an organic solvent dispersion. A dispersion containing an organic solvent in the dispersion medium can replace part or all of the water contained in the dispersion with an organic solvent by, for example, a rotary evaporator, an ultrafiltration membrane, or other known methods.

[0039] Examples of the organic solvent that can be used in the zirconia-coated titanium oxide fine particle dispersion include, for example, alcohols such as methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, and octanol; esters such as ethyl acetate, butyl acetate, ethyl lactate, propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate, and γ-butyrolactone; ethers such as diethyl ether, ethylene glycol monomethyl ether (methyl cellosolve), ethylene glycol monoethyl ether (ethyl cellosolve), ethylene glycol monobutyl ether (butyl cellosolve), diethylene glycol monomethyl ether, and diethylene glycol monoethyl ether; ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, acetylacetone, and cyclohexanone; aromatic hydrocarbons such as benzene, toluene, xylene, and ethylbenzene; cyclic hydrocarbons such as cyclohexane; Examples of the amides include dimethylformamide, N,N-dimethylacetoacetamide, N-methylpyrrolidone and the like. These organic solvents may be used alone or in combination of two or more kinds.

[0040] [Method for producing dispersion of zirconia-coated titanium oxide fine particles] The method for producing the zirconia-coated titanium oxide fine particle dispersion according to the present invention includes the following steps (1) to (3).

[0041] Step (1) Step (1) is a step of preparing a dispersion liquid (1) of titanium oxide fine particles that satisfies the requirement (a).

[0042] The titanium oxide fine particles are used as core particles. In step (1), for example, If it is a dispersion of anatase-type titanium oxide fine particles, the method described in JP-A-63-229139, If it is a dispersion of rutile-type titanium oxide fine particles, the methods described in JP-A-02-255532, JP-A-08-048940, JP-A-2000-204301, JP-A-2002-363442, JP-A-2012-056816, JP-A-2015-193757, If it is a dispersion of metal-supported titanium oxide fine particles, the methods described in JP-A-01-301517, JP-A-08-239223, JP-A-11-172152, WO 2018 / 181241, If it is a dispersion of fine particles composed of a rutile-type titanium oxide fired product, a dispersion of titanium oxide fine particles (core particles) can be prepared (prepared) by the methods described in JP-A-2010-168266, JP-A-2011-132484, JP-A-2011-136850, WO 2010 / 073772.

[0043] Alternatively, a dispersion of titanium oxide fine particles may be prepared by purchasing a commercially available product. The titanium oxide fine particles preferably satisfy the above requirement (a). The details of the titanium oxide fine particles are as described above.

[0044] Step (2) In step (2), after adding an aqueous solution of zirconium peroxoacid to the dispersion liquid (1), the fine particles obtained by the reaction between the titanium oxide fine particles and the zirconium peroxoacid (hereinafter also referred to as "reaction fine particles (2a)") are aged to obtain a dispersion liquid (2) of a zirconia-coated titanium oxide fine particle precursor (2b).

[0045] The aqueous solution of zirconium peroxoacid may be prepared, for example, by the method described in JP-A-2012-056816, that is, by peptizing a zirconia sol using potassium hydroxide and hydrogen peroxide solution.

[0046] The amount of the aqueous solution of zirconium peroxoacid added to the dispersion liquid (1) is set to be 1 to 50 parts by mass, preferably 2 to 40 parts by mass, in terms of the mass of ZrO2, relative to 100 parts by mass of the titanium oxide fine particles which are the core particles.

[0047] The temperature at which the aqueous solution of zirconium peroxoacid is added is preferably 10 to 40°C, more preferably about room temperature (20 to 25°C). When the temperature is within this range, it is possible to prevent the proportion of zirconium peroxoacid contributing to the formation of the coating layer from decreasing due to the progress of decomposition and gelation by heating.

[0048] The addition time of the aqueous solution of zirconium peroxoacid is preferably within 2 hours. The aging is preferably carried out by heating the dispersion liquid containing the reaction fine particles (2a) at 50 to 80°C for preferably 0.5 to 18 hours.

[0049] By carrying out step (2) under such conditions, in step (2), when the average particle diameter and haze (%) of the reaction fine particles (2a) at the end of the addition of the zirconium peroxoacid aqueous solution are D2 and Hz2 respectively, and the average particle diameter and haze (%) of the precursor (2b) (that is, the reaction fine particles (2a) after aging) are D3 and Hz3 respectively, D3 / D2 can be 1.1 to 3.0 and Hz3 / Hz2 can be 0.8 to 1.2. When the D3 / D2 and Hz3 / Hz2 are within the above ranges, the decomposition or gelation of zirconium peroxoacid can be moderately suppressed, and a uniform zirconia coating layer can be formed on the core particles.

[0050] D3 / D2 is preferably 1.2 to 2.5, and Hz3 / Hz2 is preferably 0.8 to 1.1. In the present invention, the haze is the haze measured by adjusting fine particles, precursors, etc. to be measured to a dispersion (the dispersion medium is water unless otherwise specified) with a solid content concentration of 1.5% by mass and placing it in a quartz cell with an optical path length of 33 mm. These average particle diameter and haze values are, more specifically, the values measured by the method adopted in the examples described later.

[0051] Step (3) Step (3) is a step of obtaining a zirconia-coated titanium oxide fine particle dispersion by hydrothermally treating the dispersion (2) after adjusting the solid content concentration to 0.01 to 10% by mass.

[0052] When high-concentration impurity ions are present in the dispersion (2), desired fine particles may not be obtained in step (3). Therefore, the solid content concentration of the dispersion (2) is adjusted to 0.01 to 10% by mass, preferably 0.01 to 5% by mass, before hydrothermal treatment. Usually, the solid content concentration is reduced and the concentration of impurity ions is reduced by diluting the dispersion (2). Dilution is usually carried out by adding water.

[0053] This solid content concentration value is the ratio of the mass of the ignited residue (solid content) obtained by firing the measurement sample at 1000 °C for 1 hour after removing the solvent to the mass of the measurement sample. The hydrothermal treatment is preferably carried out in a pressure-resistant and heat-resistant container, more preferably an autoclave made of stainless steel.

[0054] Also, the hydrothermal treatment is preferably carried out under temperature conditions of 130 to 250 °C, more preferably 150 to 200 °C, and preferably for 10 to 100 hours, more preferably for 12 to 40 hours. When the hydrothermal treatment is carried out under the above conditions, the zirconium compound added in the step (2) can coat the surface of the core particles more strongly, and a zirconia-coated titanium oxide fine particle dispersion can be obtained.

[0055] By carrying out the step (3) under such conditions, when the average particle diameter and the fading rate of the titanium oxide fine particles are D1 and PA1 respectively, and the average particle diameter and the fading rate of the zirconia-coated titanium oxide fine particles are D4 and PA4 respectively, D4 / D1 can be 0.8 to 1.2 (preferably 0.9 to 1.1) and PA4 / PA1 can be 0.4 or less. The lower limit value of PA4 / PA1 may be 0.001, for example. The fact that D4 / D1 and PA4 / PA1 are within the above ranges means that a dense zirconia coating layer is sufficiently formed in a state where the titanium oxide fine particles are dispersed. When used as a paint composition, a transparent cured coating film can be obtained, and moreover, since the photocatalytic activity is well suppressed, it means that excellent weather resistance and light resistance are exhibited.

[0056] The zirconia-coated titanium oxide fine particles may be isolated from the zirconia-coated titanium oxide fine particle dispersion obtained in the step (3). As the isolation method, a conventionally known method can be adopted.

[0057] As the zirconia-coated titanium oxide fine particles according to the present invention, in addition to the zirconia-coated titanium oxide fine particles (I) described above, zirconia-coated titanium oxide fine particles isolated from a zirconia-coated titanium oxide fine particle dispersion liquid produced by the method including the above-described steps (1) to (3) (hereinafter also referred to as "zirconia-coated titanium oxide fine particles (II)") are also included.

[0058] (Surface treatment of zirconia-coated titanium oxide fine particles) When dispersing the zirconia-coated titanium oxide fine particles in an organic solvent or a solution in which a resin is dispersed, in order to prevent aggregation of the zirconia-coated titanium oxide fine particles in the dispersion liquid, a hydrophobic treatment may be performed on the surface of the zirconia-coated titanium oxide fine particles using a surface treatment agent.

[0059] The step of performing this hydrophobic treatment is a step of adding a surface treatment agent to the dispersion liquid and further performing heating or hydrothermal treatment as necessary, and may be performed before the operation of replacing the water in the above-described aqueous dispersion liquid with a solvent (hereinafter also referred to as "solvent replacement operation"), or may be performed simultaneously with or after the solvent replacement operation. Also, at this time, a catalyst such as ammonia may be used as necessary.

[0060] As the surface treatment agent, known ones such as alkoxide compounds such as tetraethoxysilane and triisopropoxyaluminum, coupling agents such as silane coupling agents or titanium coupling agents, low molecular weight or high molecular weight surfactants such as nonionic, cationic or anionic surfactants, and metal soap salts such as metal salts of fatty acids or metal salts of naphthenic acids can be used.

[0061] As a method of using the zirconia-coated titanium oxide fine particle water and / or organic solvent dispersion liquid thus obtained as a coating liquid for forming a coating film, or a method of blending it into a resin composition, a conventionally known method can be used as appropriate.

[0062] [Coating composition] The coating composition according to the present invention is a coating composition containing zirconia-coated titanium oxide fine particles and a matrix component according to the present invention. This coating composition may further contain a curing catalyst or an additive.

[0063] The coating composition may be a thermosetting coating composition or a photocurable coating composition. The thermosetting coating composition contains zirconia-coated titanium oxide fine particles, a matrix component, and, if necessary, a curing catalyst or an additive for thermosetting. By mixing these components, it can be produced, for example, based on the description in JP-A-2000-204301.

[0064] The photocurable coating composition contains zirconia-coated titanium oxide fine particles, a matrix component, and, if necessary, a curing catalyst or an additive for photocuring. By mixing these components, it can be produced, for example, based on the description in JP-A-2009-056387.

[0065] Examples of the matrix component include methyltrimethoxysilane, ethyltriethoxysilane, methyltriethoxysilane, phenyltriethoxysilane, dimethyldimethoxysilane, phenylmethyldimethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, vinyltris(β-methoxyethoxy)silane, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropyltriethoxysilane, γ-glycidoxypropylmethyldimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, γ-methacryloxypropyltrimethoxysilane, N-β(aminoethyl)γ-aminopropyltrimethoxysilane, N-β(aminoethyl)γ-aminopropylmethyldimethoxysilane, γ-aminopropyltriethoxysilane, N-phenyl-γ-aminopropyltrimethoxysilane, and γ-mercaptopropyltrimethoxysilane. These may be used alone or in combination of two or more.

[0066] Examples of the curing catalyst for thermosetting include amines such as n-butylamine, triethylamine, guanidine, and biguanide; amino acids such as glycine; metal acetylacetonates such as aluminum acetylacetonate, chromium acetylacetonate, titanyl acetylacetonate, and cobalt acetylacetonate; metal salts of organic acids such as sodium acetate, zinc naphthenate, cobalt naphthenate, zinc octylate, and tin octylate; perchloric acids or their salts such as perchloric acid, ammonium perchlorate, and magnesium perchlorate; acids such as hydrochloric acid, phosphoric acid, nitric acid, and p-toluenesulfonic acid; or metal chlorides which are Lewis acids such as SnCl2, AlCl3, FeCl3, TiCl4, and ZnCl2. These may be used alone or in combination of two or more.

[0067] Examples of the curing catalyst for photocuring include bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide, bis(2,6-dimethoxybenzoyl)-2,4,4-trimethyl-pentylphosphine oxide, 2-hydroxy-methyl-2-methyl-phenyl-propan-1-one, 2,2-dimethoxy-1,2-diphenylethane-1-one, 1-hydroxy-cyclohexyl-phenyl-ketone, and 2-methyl-1-[4-(methylthio)phenyl]-2-morpholinopropan-1-one.

[0068] These may be used alone or in combination of two or more. Examples of the additive include surfactant, leveling agent, ultraviolet absorber, light stabilizer, diluting solvent, preservative, antifouling agent, antibacterial agent, defoaming agent, ultraviolet degradation inhibitor, and dye. These may be used alone or in combination of two or more.

[0069] [Substrate with coating film] The substrate with a coating film according to the present invention is a substrate with a coating film having a substrate and a coating film formed from the coating composition according to the present invention provided on the surface of the substrate.

[0070] Examples of the base material include various base materials made of glass, plastic, etc., and specific examples include plastic base materials used as optical lenses and the like. The film thickness of the coating film varies depending on the use of the coated base material, but is preferably 0.03 to 30 μm.

[0071] When the coated base material according to the present invention uses the thermosetting paint composition, it can be manufactured, for example, based on the description in JP-A-2000-204301. When the photocurable paint composition is used, it can be manufactured, for example, based on the description in JP-A-2009-56387. The thermosetting paint composition or the photocurable paint composition is applied to the base material by a known method such as dipping method, spraying method, spinner method, roll coating method, bar coater method, etc., dried, and cured by heat treatment or ultraviolet irradiation, etc.

[0072] When manufacturing the coated base material according to the present invention, for the purpose of improving the adhesion between the base material, for example, a plastic base material and the coating film, the surface of the base material may be treated in advance with an alkali, an acid or a surfactant, polished with inorganic or organic fine particles, or subjected to primer treatment or plasma treatment.

Examples

[0073] Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples. [Measurement method or evaluation method] Various measurements or evaluations were performed as follows.

[0074] [1] Average particle diameter Each particle was diluted with a dispersion medium so that the solid content concentration became 0.1% by mass, and the particle size distribution was measured using a fine particle size measuring device (ELS-Z manufactured by Otsuka Electronics Co., Ltd.) based on the dynamic light scattering method. The refractive index and viscosity of the solution were the refractive index and viscosity of each dispersion medium, respectively. The average particle diameter was determined by cumulant analysis.

[0075] [2] Evaluation of haze (Hz) The measurement sample was adjusted to a solid content concentration of 1.5% by mass by water dilution or concentration with a rotary evaporator, placed in a cell with an optical path length of 33 mm, and the haze was measured with a color difference and turbidity meter (COH-400, manufactured by Nippon Denshoku Industries Co., Ltd.).

[0076] [3] Solid content concentration After removing the solvent contained in the measurement sample by infrared irradiation or the like, the residue was calcined at 1000 °C for 1 hour to obtain the ignited residue (solid content). The ratio of the mass of the ignited residue to the mass of the sample was defined as the solid content concentration.

[0077] [4] Method for measuring particle composition (Titanium, tin, silicon, iron and antimony) A water dispersion of the measurement sample (inorganic oxide particles such as titanium oxide fine particles) was collected in zirconia balls, the water was removed by infrared irradiation, and then the obtained dried product was heated and melted by adding Na2O2 and NaOH. Sulfuric acid and hydrochloric acid were further added to the obtained melt, and water was added for dilution. Using an ICP apparatus (ICPS-8100, manufactured by Shimadzu Corporation), the amounts of titanium, tin, silicon, iron, and antimony in the obtained solution were measured in terms of oxide conversion (TiO2, SnO2, SiO2, Fe2O3, Sb2O5).

[0078] (Nickel, zirconium, aluminum) A water dispersion of the measurement sample was collected in a platinum dish, hydrofluoric acid and sulfuric acid were added and heated, and then water was added to dissolve the inorganic oxide particles. After further diluting this with water, the amounts of nickel, zirconium, and aluminum were measured in terms of oxide conversion (NiO, ZrO2, Al2O3) using an ICP apparatus (ICPS-8100, manufactured by Shimadzu Corporation).

[0079] (Potassium) A water dispersion of the measurement sample was collected in a platinum dish, hydrofluoric acid and sulfuric acid were added, and the mixture was heated. Then, hydrochloric acid was added to dissolve the inorganic oxide particles. Further, after diluting this with water, the amount of potassium was measured in terms of oxide conversion (K2O) using an atomic absorption spectrometer (Z-5300, manufactured by Hitachi, Ltd.). Based on these measurement results, the content of each component in the inorganic oxide fine particles was calculated.

[0080] [5] Crystal form of particles Approximately 30 ml of the water dispersion of the measurement sample was collected in a magnetic crucible (type B-2), dried at 110 °C for 12 hours, and then the residue was placed in a desiccator and cooled to room temperature. Next, after pulverizing the residue in a mortar for 15 minutes, the crystal form was measured using an X-ray diffractometer (RINT1400, manufactured by Rigaku Corporation).

[0081] [6] Observation of particles The shape of the measurement sample was observed at an acceleration voltage of 30 kV using a scanning electron microscope (SEM) (S-5500, manufactured by Hitachi High-Technologies Corporation). The sample for observation was prepared as follows. The water dispersion sol of the measurement sample was diluted with water to a solid content concentration of 0.05 mass%, then applied to a metal grid with a collodion film (manufactured by Oken Shoji Co., Ltd.), irradiated with a 250 W lamp for 30 minutes to disperse the solvent, and a sample for observation was prepared.

[0082] [7] Evaluation of the photocatalytic activity inhibition effect of titanium oxide fine particles (measurement of discoloration rate) An appropriate solvent was added to a water dispersion of inorganic oxide fine particles in an amount corresponding to 0.05 g in terms of solid content mass so that the ratio of water / methanol = 1 / 1 (mass ratio) and the solid content concentration was 0.5 mass%. Next, the obtained dispersion and a glycerin solution of sunset yellow FCF dye with a solid content concentration of 0.02 mass% were mixed so that the mass ratio (mass of dispersion / mass of glycerin solution) was 1 / 3 to prepare a sample, which was placed in a quartz cell with a depth of 1 mm, a width of 1 cm, and a height of 5 cm. Next, using an ultraviolet lamp (LUV-6, manufactured by AS ONE) with a wavelength range of I-line (wavelength 365 nm), the intensity was 0.4 mW / cm from a distance of 5.5 cm with respect to the surface of the quartz cell with a width of 1 cm × height of 5 cm 2Ultraviolet light was irradiated at (wavelength converted to 365 nm).

[0083] The absorbance (A0) of the sample before ultraviolet irradiation at a wavelength of 490 nm and the absorbance (A n ) after n hours of ultraviolet irradiation were measured with an ultraviolet-visible spectrophotometer (JASCO, V-550), and the fading rate of the dye was calculated from the following formula. Fading change rate = (A n - A0) / A0 × 100 (%) PA (fading rate) = Fading change rate / UV irradiation time (% / h)

[0084] The irradiation time of ultraviolet light was adjusted as follows according to the fading rate. (1) When the fading rate is 30% / h or more, the time until the fading change rate reaches 70 - 90% (2) When the fading rate is 3 or more and less than 30% / h, 3 hours (3) When the fading rate is less than 3% / h, it was set to 20 hours.

[0085] [8] Method for measuring film thickness and refractive index of coating film Using an optical measuring device (OLYMPUS USPM-RU III), the reflectance spectra of the coating film and the coated substrate were measured, and the film thickness and refractive index of the coating film were calculated.

[0086] [9] Method for measuring particle refractive index Using the method described in

[0105] -

[0110] of JP-A-2010-168266, a plurality of coating films with different ratios of titanium oxide fine particles to the matrix were prepared, the refractive index of each coating film was determined by the above method, and the particle refractive index was calculated from them.

[0087]

[10] Weather resistance evaluation of thermosetting coating film On the surface of the coating film of the substrate with the thermosetting coating film, 11 parallel scratches were made at intervals of 1 mm vertically and horizontally with a knife to create 100 meshes. Then, for the substrate with the thermosetting coating film, using a QUV accelerated weathering tester (Q-lab, QUV / spray), irradiation was performed with a UVA-340 lamp at an irradiation intensity of 0.70 W / m 2、Using a cycle of 8 hours at 60°C and 4 hours at 50°C under humidification for a total of 12 hours, a 2-cycle (24-hour) exposure acceleration test was conducted.

[0088] Furthermore, a NICHIBAN cellophane adhesive tape (CT405AP-15) was adhered to the grid pattern, and then the cellophane adhesive tape was peeled off to check for the presence or absence of peeling of the grid pattern. If there was no peeling of the grid pattern, the exposure acceleration test was performed again, and then the operation of adhering the cellophane adhesive tape to the grid pattern and then peeling off the cellophane adhesive tape was repeated. The total UV irradiation time until one or more grid patterns peeled off was determined to evaluate the weather resistance adhesion. In addition, the time until cracks were visually confirmed in the coating film of the photocurable coating film-attached film prepared separately was measured to evaluate the weather resistance cracking property.

[0089] [Example 1] Step (1) [Production of Titanium Oxide Fine Particles 1] 9.37 kg of an aqueous titanium tetrachloride solution containing 7.75% by mass in terms of TiO2 (manufactured by Osaka Titanium Technologies Co., Ltd.) and aqueous ammonia containing 15% by mass of ammonia (manufactured by Ube Industries, Ltd.) were mixed to prepare a white slurry solution with a pH of 9.5. Next, after filtering the slurry, the filtrate was washed with water to obtain 7.27 kg of a hydrated titanic acid cake with a solid content concentration of 10% by mass.

[0090] To the cake, 8.30 kg of an aqueous hydrogen peroxide solution containing 35% by mass of hydrogen peroxide (manufactured by Mitsubishi Gas Chemical Company, Inc.) and 41.1 kg of water were added, and then stirred at 80°C for 1 hour. Further, 15.9 kg of water was added to obtain 72.6 kg of an aqueous titanic acid peroxide solution 1 containing 1% by mass of titanium oxide in terms of TiO2. The aqueous titanic acid peroxide solution 1 was transparently yellow, had a pH of 8.5, and the average particle diameter of the fine particles in the aqueous solution was 35 nm.

[0091] The cation exchange resin (manufactured by Mitsubishi Chemical Corporation) was mixed with the aqueous titanic acid peroxide solution 1 (72.6 kg), and to this, 9.07 kg of an aqueous potassium stannate solution containing 1% by mass of potassium stannate in terms of SnO2 (manufactured by Showa Chemical Industry Co., Ltd.) was gradually added with stirring.

[0092] After separating the cation exchange resin that had absorbed potassium ions and the like from the resulting aqueous solution, 112 g of silica microparticle sol 1 containing 0.4 mass % of aluminum in terms of Al2O3 (hereinafter also referred to as "silica-based sol 1"; pH 2.2, solid content 16 mass %, manufactured by JGC Catalysts and Chemicals Co., Ltd.) and 1.79 kg of water were mixed, and the resulting mixture was heated in an autoclave (manufactured by Taiatsu Glass Industry Co., Ltd., 120 L) at 165°C for 18 hours.

[0093] The obtained sol was cooled to room temperature and then concentrated using an ultrafiltration membrane device (ACV-3010, manufactured by Asahi Kasei Corporation) to obtain 9.5 kg of a water-dispersed sol with a solid content concentration of 10% by mass. The fine particles contained in the obtained water-dispersed sol were titanium oxide fine particles having a rutile crystal structure and containing tin and silicon (hereinafter referred to as "titanium oxide fine particles 1"). The composition and physical properties of titanium oxide fine particles 1 are shown in Table 1-1.

[0094] Step (2) (Step (2a)) Ammonia water containing 15% by mass of ammonia was gradually added to 2.63 kg of an aqueous solution of zirconium oxychloride (manufactured by Taiyo Koko Co., Ltd.) containing 2% by mass of zirconium oxychloride calculated as ZrO2 while stirring to obtain a slurry liquid with a pH of 8.5. Next, this slurry was filtered and washed with water to obtain 526 g of a zirconia cake containing 10% by mass of ZrO2.

[0095] 180 g of water was added to 20 g of the cake, and 4.0 g of potassium hydroxide granules containing 85% by mass of potassium hydroxide (Kanto Chemical Co., Inc.) was added to make the system alkaline. 40 g of hydrogen peroxide solution containing 35% by mass of hydrogen peroxide was then added, and the mixture was heated to 50°C to dissolve the cake. 156 g of water was then added to obtain 400 g of aqueous zirconium peroxide solution 1 containing 0.5% by mass, calculated as ZrO. The pH of this aqueous zirconium peroxide solution 1 was 12.9, the haze was 1.4%, and the average particle size was unmeasurable due to insufficient scattering intensity.

[0096] (Step (2b)) The titanium oxide fine particles 1 were diluted with water to prepare 70 g of a sol having a solid content concentration of 2% by mass. To this sol, 19.6 g of the zirconium peroxoacid aqueous solution 1 was added at room temperature and stirred to obtain a zirconium peroxoacid aqueous solution mixture (hereinafter also referred to as "zirconium peroxoacid aqueous solution mixture 1" or "mixture 1"). The average particle diameter (D2) of the fine particles in mixture 1 was 19.7 nm, and the haze (Hz2) was 9.6%.

[0097] The zirconium peroxoacid aqueous solution mixture 1 was heat-treated at 60°C for 6 hours and then cooled to obtain a dispersion of a zirconia-coated titanium oxide fine particle precursor (hereinafter also referred to as "precursor 1"). The average particle diameter (D3) of precursor 1 was 26.1 nm, and the haze (Hz3) was 9.8%.

[0098] Step (3) The dispersion of precursor 1 obtained in step (2) was diluted with water so that the solid content concentration became 0.1% by mass, and then hydrothermally treated at 165°C for 18 hours in an autoclave to obtain a dispersion of zirconia-coated titanium oxide fine particles (hereinafter referred to as "coated fine particles 1"). The average particle diameter (D4) of coated fine particles 1 was 19.2 nm, and the haze (Hz4) was 7.8%. When the photoactivity was evaluated, the fading rate (PA4) was 5.7 (% / h). In the SEM of the same product, spindle-shaped particles having a major axis of about 15 - 20 nm were observed as in the case of the titanium oxide fine particles 1. Further, when the same product was dried and XRD was measured, only a rutile-type diffraction pattern was confirmed.

[0099] [Example 2] Step (1) Step (1) of Example 1 was carried out. Step (2) A dispersion of a zirconia-coated titanium oxide fine particle precursor (hereinafter also referred to as "precursor 2") was obtained in the same manner as in step (2) of Example 1, except that the heat treatment conditions of the zirconium peroxoacid aqueous solution mixture 1 in step (2) were 80°C for 1 hour. The physical properties of precursor 2 are shown in Table 1-2. Step (3) A dispersion of zirconia-coated titanium oxide fine particles (hereinafter referred to as "coated fine particles 2") was obtained in the same manner as in step (3) of Example 1, except that the dispersion of precursor 1 was changed to the dispersion of precursor 2. The physical properties of the coated fine particles 2 are shown in Table 1-3.

[0100] [Example 3] Step (1) Step (1) of Example 1 was carried out. Step (2) A dispersion of zirconia-coated titanium oxide fine particle precursor (hereinafter also referred to as "precursor 3") was obtained in the same manner as in step (2) of Example 1, except that the heat treatment conditions of the zirconium peroxoacid aqueous solution mixture 1 in step (2) were changed to 80 °C for 3 hours. The physical properties of the precursor 3 are shown in Table 1-2. Step (3) A dispersion of zirconia-coated titanium oxide fine particles (hereinafter referred to as "coated fine particles 3") was obtained in the same manner as in step (3) of Example 1, except that the dispersion of precursor 1 was changed to the dispersion of precursor 3. The physical properties of the coated fine particles 3 are shown in Table 1-3.

[0101] [Example 4] Step (1) Step (1) of Example 1 was carried out. Step (2) A dispersion of zirconia-coated titanium oxide fine particle precursor (hereinafter also referred to as "precursor 4") was obtained in the same manner as in step (2) of Example 3, except that the amount of the zirconium peroxoacid aqueous solution 1 added to the sol of the titanium oxide fine particles 1 was changed to 14 g. The physical properties of the precursor 4 are shown in Table 1-2. Step (3) A dispersion of zirconia-coated titanium oxide fine particles (hereinafter also referred to as "coated fine particles 4") was obtained in the same manner as in step (3) of Example 2, except that the dispersion of precursor 2 was changed to the dispersion of precursor 4. The physical properties of the coated fine particles 4 are shown in Table 1-3.

[0102] [Example 5] Step (1) Step (1) of Example 1 was carried out. Step (2) Step (2a) of Example 1 was carried out to obtain an aqueous zirconium peroxide solution 1. Titanium oxide fine particles 1 were diluted with water to prepare 70 g of a sol having a solid content concentration of 0.2% by mass. 98 g of the aqueous zirconium peroxide solution 1 was added and stirred at room temperature to obtain an aqueous zirconium peroxide solution mixture 5. The average particle diameter (D2) of the fine particles contained in the mixture 5 was 19.6 nm, and the haze (Hz2) was 11.5%. The aqueous zirconium peroxide solution mixture 5 was heat-treated at 80 °C for 18 hours and then cooled to obtain a dispersion of zirconia-coated titanium oxide fine particle precursor (hereinafter also referred to as "precursor 5"). The physical properties of the precursor 5 are shown in Table 1-2. Step (3) The dispersion of the precursor 5 was diluted with water so that the solid content concentration became 0.2% by mass, and then hydrothermally treated at 165 °C for 18 hours in an autoclave to obtain a dispersion of zirconia-coated titanium oxide fine particles (hereinafter also referred to as "coated fine particles 5"). The physical properties of the coated fine particles 5 are shown in Table 1-3.

[0103] [Example 6] Step (1) [Production of titanium oxide fine particle dispersion] 93.01 kg of the titanium tetrachloride aqueous solution and 0.618 kg of an aqueous solution containing 10% by mass of iron oxide in terms of Fe2O3 (manufactured by Hayashi Pure Chemical Industries, Ltd.) were mixed. Then, this mixture and the aqueous ammonia were mixed to prepare a yellowish-brown slurry solution with a pH of 9.5. Next, after filtering this slurry, the filtrate was washed with water to obtain 72.7 kg of an iron-containing hydrous titanic acid cake having a solid content concentration containing iron of 10% by mass.

[0104] 83.0 kg of the hydrogen peroxide solution and 411.4 kg of water were added to the cake, and then stirred at a temperature of 80 °C for 1 hour. Further, 159 kg of water was added to obtain 726 kg of an iron-containing aqueous titanic acid solution. The iron-containing aqueous titanic acid solution was transparent and yellowish-brown, had a pH of 8.5, and the average particle diameter of the fine particles in the aqueous solution was 35 nm.

[0105] 72.9 kg of the iron-containing aqueous solution of peroxytitanic acid was mixed with 3.5 kg of a cation exchange resin, and 9.11 kg of the aqueous solution of potassium stannate was gradually added thereto with stirring. After separating the cation exchange resin that had absorbed potassium ions and the like from the resulting aqueous solution, 1.125 kg of the silica-based sol 1 and 18.0 kg of water were mixed and heated in an autoclave (manufactured by Taiatsu Glass Industry Co., Ltd., 120 L) at 165°C for 18 hours.

[0106] The obtained sol was cooled to room temperature and then concentrated using an ultrafiltration membrane device (ACV-3010, manufactured by Asahi Kasei Corporation) to obtain 10.0 kg of a water-dispersed sol with a solid content concentration of 10% by mass. The fine particles contained in the water-dispersed sol thus obtained were iron-containing titanium oxide fine particles having a rutile crystal structure and containing tin and silicon (hereinafter referred to as "titanium oxide fine particles 6"). The composition and physical properties of titanium oxide fine particles 6 are shown in Table 1-1.

[0107] Steps (2) and (3) An aqueous zirconic acid peroxide mixture (hereinafter referred to as "Mixture 6") was obtained in the same manner as in steps (2) and (3) of Example 3, except that titanium oxide microparticles 6 were used instead of titanium oxide microparticles 1. A dispersion of a zirconia-coated titanium oxide microparticle precursor (hereinafter referred to as "Precursor 6") was then obtained, and a dispersion of zirconia-coated titanium oxide microparticles (hereinafter referred to as "Coated Microparticles 6") was then obtained in the same manner as in steps (2) and (3) of Example 3. The physical properties of the microparticles contained in Mixture 6, Precursor 6, and Coated Microparticles 6 are shown in Tables 1-2 and 1-3.

[0108] [Example 7] Step (1) [Production of titanium oxide fine particle dispersion] Except that the amount of the titanium tetrachloride aqueous solution was 91.50 kg and the amount of the ferric chloride aqueous solution was 1.818 kg, a water-dispersed sol having a solid content concentration of 10% by mass was obtained in the same manner as in step (1) of Example 6. The fine particles contained in the water-dispersed sol had a rutile-type crystal structure and were iron-containing titanium oxide fine particles containing tin and silicon (hereinafter referred to as "titanium oxide fine particles 7"). The composition and various physical properties of the titanium oxide fine particles 7 are shown in Table 1-1.

[0109] Steps (2) and (3) Except that titanium oxide fine particles 7 were used instead of titanium oxide fine particles 1, a zirconium peroxide aqueous acid mixture (hereinafter referred to as "mixture 7") was obtained in the same manner as in steps (2) and (3) of Example 3, and then a dispersion of a zirconia-coated titanium oxide fine particle precursor (hereinafter referred to as "precursor 7") was obtained, and then a dispersion of zirconia-coated titanium oxide fine particles (hereinafter referred to as "coated fine particles 7") was obtained. The various physical properties of the fine particles contained in mixture 7, precursor 7, and coated fine particles 7 are shown in Tables 1-2 and 1-3.

[0110] [Example 8] Step (1) After mixing 180.3 g of the titanium tetrachloride aqueous solution and 1.45 g of a nickel chloride aqueous solution containing 7.75 Mass % of nickel chloride hexahydrate (manufactured by Kanto Chemical Co., Inc.) in terms of NiO, this mixture and aqueous ammonia were mixed to prepare a pale green slurry solution with a pH of 9.0. Then, after filtering this slurry, the filtrate was washed with water to obtain 100 g of a nickel-containing hydrous titanic acid cake having a solid content concentration containing nickel of 12.7% by mass.

[0111] To 17.2 g of the cake, 25.0 g of hydrogen peroxide solution and 128.6 g of water were added, and then stirred at 80 °C for 1 hour, and further 46.2 g of water was added to obtain 217 g of an Ni-containing peroxotitanic acid aqueous solution. This Ni-containing peroxotitanic acid aqueous solution was transparent yellow, had a pH of 8.0, and the average particle diameter of the fine particles in the aqueous solution was 47 nm.

[0112] Next, the cation exchange resin was mixed with 217 g of the aqueous solution of titanium peroxide containing Ni, and 27.3 g of the aqueous solution of potassium stannate was gradually added thereto with stirring. After separating the cation exchange resin that had taken in potassium ions and the like from the obtained aqueous solution, 3.38 g of the silica-based sol 1 and 50.6 g of water were mixed, placed in a reaction decomposition vessel for high pressure (manufactured by Mitsui Chemicals, Inc.: HU-100), and heated at 165 °C for 18 hours.

[0113] Next, after cooling the obtained sol to room temperature, it was concentrated with an ultrafiltration membrane device (manufactured by Asahi Kasei Corporation, SIP-0013) to obtain 30 g of an aqueous dispersion sol having a solid content concentration of 10% by mass. The fine particles contained in the aqueous dispersion sol thus obtained had a rutile-type crystal structure and were Ni-containing titanium oxide fine particles containing tin and silicon (hereinafter referred to as "titanium oxide fine particles 8"). The composition and various physical properties of the titanium oxide fine particles 8 are shown in Table 1-1.

[0114] Steps (2) and (3) Except for using titanium oxide fine particles 8 instead of titanium oxide fine particles 1, the same procedures as in steps (2) and (3) of Example 3 were carried out to obtain an aqueous solution mixture of zirconium peroxide (hereinafter referred to as "mixture 8"), and then a dispersion of a zirconia-coated titanium oxide fine particle precursor (hereinafter referred to as "precursor 8") was obtained, and then a dispersion of zirconia-coated titanium oxide fine particles (hereinafter referred to as "coated fine particles 8") was obtained. The various physical properties of the fine particles contained in mixture 8, precursor 8, and coated fine particles 8 are shown in Tables 1-2 and 1-3.

[0115] [Example 9] Step (1) [Production of Titanium Oxide Fine Particle Dispersion] 141.9 g of the titanium tetrachloride aqueous solution and 11.52 g of a zirconium oxychloride aqueous solution containing 7.75% by mass of zirconium oxychloride (manufactured by Taiyo Kogyo Co., Ltd.) in terms of ZrO₂ were mixed. Then, this mixture and 62.86 g of the aqueous ammonia (manufactured by Ube Industries, Ltd.) were mixed to prepare a white slurry solution with a pH of 9.3. Next, after filtering this slurry, the filtrate was washed with water to obtain 100 g of a hydrous titanic acid cake with a solid content concentration of 10% by mass.

[0116] To 19.54 g of the cake, 23.11 g of hydrogen peroxide solution and 115.3 g of water were added, and then the mixture was stirred at a temperature of 80 °C for 1 hour. Further, 44.30 g of water was added to obtain 202 g of an aqueous solution 9 of zirconium-containing titanic acid peroxide. This aqueous solution 9 of zirconium-containing titanic acid peroxide was transparently yellow, had a pH of 8.1, and the average particle diameter of the fine particles in the aqueous solution was 47.1 nm.

[0117] 202 g of the aqueous solution 9 of zirconium-containing titanic acid peroxide was taken, mixed with a cation exchange resin, and 27.33 g of a potassium stannate aqueous solution was gradually added thereto with stirring. Next, after separating the cation exchange resin that had incorporated potassium ions and the like from the obtained aqueous solution, 3.37 g of the silica-based sol 1 and 50.63 g of water were mixed, placed in a high-pressure reaction decomposition vessel (manufactured by Mitsui Chemicals, Inc.: HU-100), and heated at 165 °C for 18 hours.

[0118] Next, after cooling the obtained sol to room temperature, it was concentrated with an ultrafiltration membrane device (manufactured by Asahi Kasei Corporation, SIP-0013) to obtain 30 g of an aqueous dispersion sol with a solid content concentration of 10% by mass. The fine particles contained in the aqueous dispersion sol thus obtained had a rutile-type crystal structure and were titanium oxide fine particles containing tin, silicon, and zirconium (hereinafter referred to as "titanium oxide fine particles 9"). Also, when observing the SEM of the same product, spindle-shaped particles with a major axis of about 15 to 20 nm were observed. The composition and various physical properties of the titanium oxide fine particles 9 are shown in Table 1-1.

[0119] Steps (2) and (3) Except that titanium oxide fine particles 9 were used instead of titanium oxide fine particles 1, in the same manner as in steps (2) and (3) of Example 3, an aqueous zirconium peroxide mixture (hereinafter referred to as "mixture 9") was obtained. Subsequently, a dispersion of zirconia-coated titanium oxide fine particle precursors (hereinafter referred to as "precursor 9") was obtained, and then a dispersion of zirconia-coated titanium oxide fine particles (hereinafter referred to as "coated fine particles 9") was obtained. The physical properties of the fine particles contained in mixture 9, precursor 9, and coated fine particles 9 are shown in Tables 1-2 and 1-3.

[0120] Reference Example 10] Step (1) [Manufacture of Titanium Oxide Fine Particle Dispersion] 1.61 g of antimony(III) chloride (manufactured by Fujifilm Wako Pure Chemical Corporation) was added to 137.1 g of the aqueous titanium tetrachloride solution containing 7.75% by mass of titanium tetrachloride in terms of TiO2 and dissolved. Further, 62.13 g of aqueous ammonia was mixed to prepare a white slurry solution with a pH of 8.7. Subsequently, after filtering this slurry, the filtrate was washed with water to obtain 100 g of a water-containing titanic acid cake containing 10% by mass of antimony with a solid content concentration.

[0121] After adding 23.11 g of hydrogen peroxide solution and 115.3 g of water to 19.54 g of the cake, it was stirred at 80 °C for 1 hour, and further 44.30 g of water was added to obtain 202 g of an aqueous titanic acid solution containing antimony. This aqueous titanic acid solution was transparent yellow, had a pH of 8.3, and the average particle diameter of the fine particles in the aqueous solution was 42.9 nm.

[0122] Next, 202 g of the antimony-containing aqueous titanic acid solution was taken, mixed with a cation exchange resin, and 27.33 g of an aqueous potassium stannate solution was gradually added thereto with stirring. After separating the cation exchange resin that had taken in potassium ions and the like from the obtained aqueous solution, 3.37 g of the silica-based sol 1 and 50.63 g of water were mixed, placed in a reaction decomposition container for high pressure (manufactured by Mitsui Chemicals, Inc.: HU-100), and heated at 165 °C for 18 hours.

[0123] ​Next, after cooling the obtained sol to room temperature, it was concentrated using an ultrafiltration membrane device (manufactured by Asahi Kasei Corporation, SIP-0013) to obtain 30 g of an aqueous dispersion sol having a solid content concentration of 10% by mass. The fine particles contained in the aqueous dispersion sol thus obtained had anatase-type crystal structure and were titanium oxide fine particles containing tin, silicon, and antimony (hereinafter referred to as "titanium oxide fine particles 10"). The composition and various physical properties of the titanium oxide fine particles 10 are shown in Table 1-1.

[0124] Steps (2) and (3) An aqueous zirconium peroxoacid solution mixture (hereinafter referred to as "mixture 10") was obtained in the same manner as in steps (2) and (3) of Example 3 except that titanium oxide fine particles 10 were used instead of titanium oxide fine particles 1. Subsequently, a dispersion of a zirconia-coated titanium oxide fine particle precursor (hereinafter referred to as "precursor 10") was obtained, and then a dispersion of zirconia-coated titanium oxide fine particles (hereinafter referred to as "coated fine particles 10") was obtained. The various physical properties of the fine particles contained in mixture 10, precursor 10, and coated fine particles 10 are shown in Tables 1-2 and 1-3.

[0125] [Example 11] Step (1) [Production of Titanium Oxide Fine Particle Dispersion] To 149.6 g of the aqueous titanium tetrachloride solution, 0.13 g of an aqueous nickel chloride solution containing 7.75 Mass % of nickel chloride hexahydrate in terms of NiO and 12.16 g of the aqueous zirconium oxychloride solution were mixed. Then, this mixture was mixed with 66.32 g of aqueous ammonia to prepare a very pale green slurry solution with a pH of 9.3. Next, after filtering this slurry, the filtrate was washed with water to obtain 100 g of a hydrous titanic acid cake containing 10% by mass of nickel and zirconium in terms of solid content.

[0126] To 19.54 g of the cake, 23.11 g of aqueous hydrogen peroxide and 115.3 g of water were added. After stirring at a temperature of 80°C for 1 hour, 44.30 g of water was further added to obtain 202 g of an aqueous titanate peroxide solution 11 containing nickel and zirconium. This aqueous titanate peroxide solution was transparently yellow, had a pH of 8.2, and the average particle diameter of the fine particles in the aqueous solution was 39.3 nm.

[0127] Next, 202 g of the aqueous titanate peroxide solution 11 containing nickel and zirconium was taken, mixed with a cation exchange resin (manufactured by Mitsubishi Chemical Corporation), and 27.33 g of the aqueous potassium stannate solution was gradually added thereto with stirring.

[0128] Next, after separating the cation exchange resin that had incorporated potassium ions and the like from the obtained aqueous solution, 3.37 g of the silica-based sol 1 and 50.63 g of water were mixed and placed in a reaction decomposition container for high pressure (manufactured by Mitsui Chemicals, Inc.: HU-100), and heated at 165°C for 18 hours.

[0129] Next, after cooling the obtained sol to room temperature, it was concentrated with an ultrafiltration membrane device (manufactured by Asahi Kasei Corporation, SIP-0013) to obtain 30 g of an aqueous dispersion sol having a solid content concentration of 10% by mass. The fine particles contained in the aqueous dispersion sol thus obtained had a rutile-type crystal structure and were titanium oxide fine particles containing tin, silicon, and antimony (hereinafter referred to as "titanium oxide fine particles 11"). When the SEM of the same product was observed, spindle-shaped particles having a major axis of about 15 to 20 nm were observed. The composition and various physical properties of the titanium oxide fine particles 11 are shown in Table 1-1.

[0130] Steps (2) and (3) Except for using titanium oxide fine particles 11 instead of titanium oxide fine particles 1, in the same manner as in steps (2) and (3) of Example 3, an aqueous zirconium peroxide solution mixture (hereinafter referred to as "mixture 11") was obtained. Then, a dispersion of zirconia-coated titanium oxide fine particle precursor (hereinafter referred to as "precursor 11") was obtained. Then, a dispersion of zirconia-coated titanium oxide fine particles (hereinafter referred to as "zirconia-coated titanium oxide fine particles 11" or "coated fine particles 11") was obtained. The physical properties of the fine particles contained in mixture 11, precursor 11, and coated fine particles 11 are shown in Tables 1-2 and 1-3.

[0131] [Example 12] Step (1) [Production of Titanium Oxide Fine Particle Dispersion] After mixing 195.8 g of the titanium tetrachloride aqueous solution and 5.15 g of the ferric chloride aqueous solution containing 7.75% by mass of ferric oxide in terms of Fe2O3, 1.15 g of the antimony(III) chloride was added and dissolved, and further 62.13 g of aqueous ammonia was mixed to prepare a pale yellow slurry solution with a pH of 9.3. Then, after filtering this slurry, the filtrate was washed with water to obtain 100 g of a hydrous titanic acid cake containing 10% by mass of iron and antimony with a solid content concentration.

[0132] To 19.54 g of the cake, 23.11 g of hydrogen peroxide solution (manufactured by Mitsubishi Gas Chemical Company, Inc.) and 115.3 g of water were added, and then stirred at 80°C for 1 hour. Further, 44.30 g of water was added to obtain 202 g of an aqueous titanic acid solution containing iron and antimony. This aqueous titanic acid solution was transparent yellow, had a pH of 7.1, and the average particle diameter of the fine particles in the aqueous solution was 42.9 nm.

[0133] Next, Containing iron and antimony 202 g of the aqueous titanic acid solution 12 was taken, mixed with a cation exchange resin, and 27.33 g of a potassium stannate aqueous solution containing 1% by mass of tin oxide in terms of SnO2 (manufactured by Showa Chemical Industry Co., Ltd.) was gradually added thereto with stirring.

[0134] Next, after separating the cation exchange resin incorporating potassium ions and the like from the obtained aqueous solution, 3.37 g of the silica-based sol 1 and 50.63 g of water were mixed and placed in a reaction decomposition container for high pressure (manufactured by Mitsui Chemicals, Inc.: HU-100), and heated at 165 °C for 18 hours.

[0135] Next, after cooling the obtained sol to room temperature, it was concentrated with an ultrafiltration membrane device (manufactured by Asahi Kasei Corporation, SIP-0013) to obtain 30 g of an aqueous dispersion sol having a solid content concentration of 10% by mass. The fine particles contained in the aqueous dispersion sol thus obtained had a rutile-type crystal structure and were titanium oxide fine particles containing tin, silicon, iron, and antimony (hereinafter referred to as "titanium oxide fine particles 12"). Further, when SEM of the same product was observed, spindle-shaped particles having a major axis of about 15 to 20 nm were observed. The composition and various physical properties of the titanium oxide fine particles 12 are shown in Table 1-1.

[0136] Steps (2) and (3) An aqueous zirconium peroxide mixture (hereinafter referred to as "mixture 12") was obtained in the same manner as in steps (2) and (3) of Example 3 except that titanium oxide fine particles 12 were used instead of titanium oxide fine particles 1. Subsequently, a dispersion of a zirconia-coated titanium oxide fine particle precursor (hereinafter referred to as "precursor 12") was obtained, and then a dispersion of zirconia-coated titanium oxide fine particles (hereinafter referred to as "zirconia-coated titanium oxide fine particles 12" or "coated fine particles 12") was obtained. The various physical properties of the fine particles contained in mixture 12, precursor 12, and coated fine particles 12 are shown in Tables 1-2 and 1-3.

[0137] [Comparative Example 1] The heat treatment conditions of the zirconium peroxoacid aqueous solution mixture 1 in Step 2 were set to 90 °C for 3 hours, and in the same manner as in Example 3 except for this, a dispersion of zirconia-coated titanium oxide fine particle precursors (hereinafter also referred to as "precursor 1B") was obtained. Subsequently, a dispersion of zirconia-coated titanium oxide fine particles (hereinafter referred to as "coated fine particles 1B") was obtained. The physical properties of precursor 1B and coated fine particles 1B are shown in Tables 1-2 and 1-3. In the SEM observation of coated fine particles 1B, in addition to spindle-shaped particles, a large amount of fine particles with a diameter of about several nm were confirmed.

[0138] [Comparative Example 2] The heat treatment conditions of the zirconium peroxoacid aqueous solution mixture 1 in Step 2 were set to 25 °C for 6 hours, and in the same manner as in Example 3 except for this, a dispersion of zirconia-coated titanium oxide fine particle precursors (hereinafter also referred to as "precursor 2B") was obtained. Subsequently, a dispersion of zirconia-coated titanium oxide fine particles (hereinafter referred to as "coated fine particles 2B") was obtained. The physical properties of precursor 2B and coated fine particles 2B are shown in Tables 1-2 and 1-3. In the SEM observation of coated fine particles 2B, in addition to spindle-shaped particles of 15-20 nm similar to titanium oxide fine particles 1 before the zirconia coating treatment, a large amount of fine particles with a diameter of about several nm were confirmed.

[0139] [Comparative Example 3] Step (1) Step (1) of Example 1 was carried out. Step (2) In the same manner as in Step (2) of Example 1, 400 g of zirconium peroxoacid aqueous solution 1 was obtained. Titanium oxide fine particles 1 were diluted with water to prepare 70 g of a sol with a solid content concentration of 2% by mass. 210 g of zirconium peroxoacid aqueous solution 1 was added and stirred at room temperature to obtain a zirconium peroxoacid aqueous solution mixture (hereinafter referred to as "mixture 3B"). After heat-treating mixture 3B at 80 °C for 3 hours and then cooling it, a dispersion of zirconia-coated titanium oxide fine particle precursors (hereinafter also referred to as "precursor 3B") was obtained.

[0140] Step (3) The dispersion of the precursor 3B was diluted with water to a solid content concentration of 0.2% by mass, and then hydrothermally treated at 165 °C for 18 hours in an autoclave to obtain a dispersion of zirconia-coated titanium oxide fine particles (hereinafter also referred to as "coated fine particles 3B"). The physical properties of the precursor 3B and the coated fine particles 3B are shown in Tables 1-2 and 1-3. The coated fine particles 3B had a high haze and were unsuitable for optical materials.

[0141] [Comparative Example 4] Step (1) Step (1) of Example 1 was carried out to obtain titanium oxide fine particles 1. Step (2) Step (2a) of Example 1 was carried out to obtain an aqueous solution of zirconium peroxoacid 1. Commercially available water glass (manufactured by AGC SI TECH Co., Ltd.) was diluted with water and then dealkalized using a cation exchange resin to obtain an aqueous silicic acid solution containing 2% by mass of a silicon component in terms of SiO2. Next, water was added to the titanium oxide fine particles 1 obtained in step (1) to prepare 140 g of a sol having a solid content concentration of 2% by mass. After heating this to a temperature of 90 °C, 9.58 g of the aqueous solution of zirconium peroxoacid 1 and 7.42 g of the aqueous silicic acid solution were gradually added respectively. After the addition was completed, it was aged for 1 hour with stirring while maintaining the temperature at 90 °C.

[0142] Step (3) The aged mixture was placed in a high-pressure reaction decomposition vessel (manufactured by Mitsuai Chemical Co., Ltd.: HU-100) and heated at 165 °C for 18 hours. In this way, a dispersion of titanium oxide fine particles coated with SiO2 / ZrO2 (hereinafter also referred to as "coated fine particles 4B") was obtained. The physical properties of the coated fine particles 4B are shown in Table 1-3.

[0143] [Comparative Example 5] A dispersion of titanium oxide fine particles coated with SiO2 / ZrO2 (hereinafter also referred to as "coated fine particles 5B") was obtained in the same manner as in Comparative Example 4, except that the amount of the zirconium peroxoacid aqueous solution 1 added in Step (2) was 34.16 g and the amount of the silicic acid aqueous solution was 26.46 g. The physical properties of the coated fine particles 5B are shown in Table 1-3.

[0144] [Preparation of Organic Solvent Dispersion, Thermosetting Coating Composition, and Substrate with Thermosetting Coating Film] [Example 13] [Preparation of Organic Solvent Dispersion] The zirconia-coated titanium oxide fine particles 3 obtained in Example 3 were concentrated using an ultrafiltration membrane device (SIP-0013, manufactured by Asahi Kasei Corporation) to obtain 60 g of an aqueous dispersion sol with a solid content concentration of 10% by mass.

[0145] This 60 g of the aqueous dispersion sol was added with stirring to a methanol solution in which 4.60 g of tetraethoxysilane (manufactured by Tama Chemical Industry Co., Ltd.) as a surface treatment agent was dissolved. Next, the obtained mixture was heated at a temperature of 50°C for 6 hours, cooled to room temperature, and then the dispersion medium in the mixture was replaced from water to methanol using an ultrafiltration membrane device, and further concentrated to obtain 13 g of a methanol dispersion sol with a solid content concentration of 20% by mass.

[0146] [Preparation of Thermosetting Coating Composition and Substrate with Thermosetting Coating Film] (1) Preparation of Thermosetting Coating Composition 0.249 g of methanol was added to 1.66 g of γ-glycidoxypropyltrimethoxysilane (manufactured by Momentive Performance Materials Japan G.K.), and 0.49 g of 0.01N hydrochloric acid was added dropwise with stirring. Further, it was stirred at room temperature for 24 hours to hydrolyze the γ-glycidoxypropyltrimethoxysilane.

[0147] Next, 6.63 g of a methanol-dispersed sol 17, 0.508 g of propylene glycol monomethyl ether (manufactured by Dow Chemical Japan), 0.285 g of itaconic acid (manufactured by Kishida Chemical), 0.103 g of dicyandiamide (manufactured by Kishida Chemical), and 0.067 g of a silicone surfactant (L-7001, manufactured by Toray Dow Corning Co., Ltd.) as a leveling agent were added to this mixed solution, and the mixture was stirred at room temperature for 24 hours. Thereby, a thermosetting paint composition (hereinafter referred to as "hard coat paint 13") was prepared.

[0148] (2) Pretreatment of the plastic lens substrate The required number of commercially available plastic lens substrates with a refractive index of 1.67 ( "Monomer name: MR-7" manufactured by Mitsui Chemicals, Inc.) was prepared, immersed in a 10% by mass KOH aqueous solution maintained at 40 ° C for 2 minutes for etching treatment, taken out and washed with water, and then dried sufficiently.

[0149] (3) Preparation of the substrate with a thermosetting coating film The hard coat paint 13 obtained above was applied to the surface of the plastic lens substrate to form a coating film. The coating composition was applied by the spin coating method and adjusted so that the film thickness after curing was 2 μm. The coating film was heat-treated at 90 ° C for 10 minutes and then at 110 ° C for 2 hours to be cured, and a substrate 13 with a thermosetting coating film was obtained.

[0150] [Example 14] Except for using coated acid fine particles 11 instead of zirconia-coated titanium oxide fine particles 3, in the same manner as in Example 13, a methanol-dispersed sol 14, a hard coat paint 14, and a substrate 14 with a thermosetting coating film were obtained.

[0151] [Example 15] Except for using coated fine particles 12 instead of zirconia-coated titanium oxide fine particles 3, in the same manner as in Example 13, a methanol-dispersed sol 15, a hard coat paint 15, and a substrate 15 with a thermosetting coating film were obtained.

[0152] [Comparative Example 6] Except for using coated fine particles 1B instead of zirconia-coated titanium oxide fine particles 3, in the same manner as in Example 13, a methanol-dispersed sol 6B, a hard coat paint 6B, and a substrate 6B with a thermoset coating film were obtained.

[0153] [Comparative Example 7] Except for using coated fine particles 4B instead of zirconia-coated titanium oxide fine particles 3, in the same manner as in Example 13, a methanol-dispersed sol 7B, a hard coat paint 7B, and a substrate 7B with a thermoset coating film were obtained.

[0154] [Comparative Example 8] Except for using coated fine particles 5B instead of zirconia-coated titanium oxide fine particles 3, in the same manner as in Example 13, a methanol-dispersed sol 8B, a hard coat paint 8B, and a substrate 8B with a thermoset coating film were obtained.

[0155] The evaluation results of the substrates with thermoset coating films obtained in Examples 13 to 15 and Comparative Examples 6 to 8 were as shown in Table 2.

[0156]

Table 1-1

[0157]

Table 1-2

[0158]

Table 1-3

[0159]

Table 2

Claims

1. (1) preparing a dispersion liquid (1) of titanium oxide fine particles that satisfies the following requirements (a) and (a'): (2) To the dispersion liquid (1), an aqueous solution of zirconium peroxydisulfate in an amount of 1 to 50 parts by mass is added with respect to 100 parts by mass of the titanium oxide fine particles in terms of the mass of ZrO 2 and then, the reaction fine particles (2a) obtained by the reaction between the titanium oxide fine particles and the zirconium peroxydisulfate are aged to obtain a dispersion liquid (2) of a zirconia-coated titanium oxide fine particle precursor (2b). (3) adjusting the solid content of the dispersion (2) to 0.01 to 10% by mass, and then subjecting the dispersion to hydrothermal treatment to obtain a dispersion of zirconia-coated titanium oxide fine particles; Including, In the step (2), when the addition of the aqueous zirconium peroxide solution is completed, the average particle size and haze (%) of the reactive fine particles (2a) are D2 and Hz2, respectively, and the average particle size and haze (%) of the precursor (2b) are D3 and Hz3, respectively, and D3 / D2 is 1.2 to 1.8, and Hz3 / Hz2 is 0.9 to 1.

1. A method for producing a dispersion of zirconia-coated titanium oxide fine particles. Requirement (a): The titanium oxide fine particles contain Ti as TiO 2 and further contains at least one metal element selected from the group consisting of Al, Zr, Sb, Zn, Ni, Fe, Ba, Mg, Sn, Si, and V. Requirement (a'): The titanium oxide fine particles are titanium oxide-based composite oxide fine particles that contain rutile-type titanium oxide containing Sn, and have a ratio of Ti to Sn in the range of 3 to 16, calculated as a TiO 2 / SnO 2 mass ratio.

2. A method for producing a zirconia-coated titanium oxide microparticle dispersion liquid described in Claim 1, wherein the aging of the reactive microparticles (2a) is carried out by heating a dispersion liquid containing the reactive microparticles (2a) at 50 to 80°C for 0.5 to 18 hours.

3. The zirconia-coated titanium oxide fine particles have titanium oxide fine particles satisfying the following requirements (a) and (a'), and a zirconia coating layer that covers the titanium oxide fine particles and satisfies the following requirement (b), and also satisfy the following requirement (c), and have an average particle diameter of 6 to 45 nm. Requirement (a): The titanium oxide fine particles contain 60% by mass or more in terms of the mass of Ti converted to TiO 2 and further contain at least one metal element selected from the group consisting of Al, Zr, Sb, Zn, Ni, Fe, Ba, Mg, Sn, Si, and V. Requirement (a'): The titanium oxide fine particles are titanium oxide-based composite oxide fine particles that contain rutile-type titanium oxide containing Sn, and have a ratio of Ti to Sn in the range of 3 to 16, calculated as a TiO 2 / SnO 2 mass ratio. Requirement (b): The amount of the zirconia coating layer is 1 to 50 parts by mass in terms of the mass of ZrO 2 converted with respect to 100 parts by mass of the titanium oxide fine particles. Requirement (c): When the average particle size and discoloration rate of the titanium oxide fine particles are D1 and PA1, respectively, and the average particle size and discoloration rate of the zirconia-coated titanium oxide fine particles are D4 and PA4, respectively, D4 / D1 is 1.0 to 1.1, and PA4 / PA1 is 0.33 or less.

4. A dispersion of the zirconia-coated titanium oxide fine particles according to claim 3.

5. A coating composition comprising the zirconia-coated titanium oxide fine particles according to claim 3 and a matrix component.

6. A coating film obtained by curing the coating composition according to claim 5.

7. A coated substrate comprising a substrate and the coating film according to claim 6 provided on the surface of the substrate.

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