Coating composition

Abstract

To provide a coating composition that can give a coating layer having excellent weather resistance.SOLUTION: A coating composition comprises titanium oxide and a hindered amine photostabilizer, wherein the titanium oxide is partly substituted with a transition metal element excluding tetravalent ones, and the hindered amine photostabilizer has a molecular structure having OH and three or more N atoms.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a highly weather-resistant coating composition. [Background technology]

[0002] Titanium dioxide is widely used as a photocatalyst, UV protection agent, and coating material for optical substrates. The well-known crystalline structures of titanium dioxide are anatase, rutile, and brookite, and different crystalline structures have different properties. For example, anatase titanium dioxide particles have high photocatalytic activity and are used as deodorizing, deodorizing, and antifouling materials. On the other hand, rutile titanium dioxide particles have a high refractive index and lower photocatalytic activity than anatase titanium dioxide particles, leading to their use in hard coat layers on substrates. Hard coat layers contain components such as organosilicon compounds and resins in addition to rutile titanium dioxide. Therefore, if the photocatalytic activity of these particles is too strong, they can decompose these components, causing cracks in the hard coat layer and reducing adhesion between the substrate and the hard coat layer. This phenomenon poses a problem (weather resistance) when substrates with titanium dioxide-containing layers are used in the presence of ultraviolet light, such as sunlight. This problem persists even with rutile titanium dioxide, which has low photocatalytic activity, and various solutions have been proposed.

[0003] For example, Patent Document 1 discloses iron-containing rutile-type titanium oxide particles in which some of the titanium sites of rutile-type titanium oxide are thought to be substituted with metal elements and all or part of silicon. It also discloses that these iron-containing rutile-type titanium oxide particles can suppress photocatalytic activity while maintaining a high refractive index.

[0004] Patent Document 2 describes a thin plastic lens for spectacles that is free from interference fringes due to the difference in refractive index between the substrate lens and the coating, and that is excellent in various durability properties such as abrasion resistance, chemical resistance, warm water resistance, heat resistance, weather resistance, and ball drop strength. It also discloses a plastic lens with a cured film, characterized in that a coating film is provided on the surface of a sulfur-containing urethane plastic lens obtained by reacting specific components, the coating film being obtained by applying and curing a coating composition containing a composite oxide of titanium, silicon, and zirconium and a specific silane coupling agent. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] International Publication No. 2018 / 181241 [Patent Document 2] Japanese Patent Application Publication No. 11-133204 Summary of the Invention [Problem to be solved by the invention]

[0006] As described above, various methods have been investigated to improve the weather resistance of coating films, but coating films with even better weather resistance have been desired.

[0007] Therefore, an object of the present invention is to provide a coating composition that can give a coating film with excellent weather resistance. [Means for solving the problem]

[0008] According to one aspect of the present invention, there is provided a coating composition comprising titanium oxide and a hindered amine light stabilizer (hereinafter also referred to as "HALS"), wherein the titanium oxide is substituted with a transition metal element other than a tetravalent element, and the molecular structure of the HALS comprises OH and three or more N atoms. [Effects of the Invention]

[0009] According to the present invention, a coating composition can be provided that can give a coating film with excellent weather resistance. DETAILED DESCRIPTION OF THE INVENTION

[0010] The present inventors have discovered that a coating film with extremely excellent weather resistance can be obtained by using a coating composition containing titanium oxide substituted with a non-tetravalent transition metal element and HALS having a molecular structure containing OH and three or more N atoms. It is known that the inclusion of HALS improves the weather resistance of coating films. However, the present invention achieves significant effects that exceed the range expected from conventional effects. When the effect of adding HALS having a molecular structure containing OH and three or more N atoms was confirmed in a weather resistance test using titanium oxide not substituted with a non-tetravalent transition metal element (a coating film was formed, irradiated with UV (ultraviolet) light, and the time until cracking occurred in the coating film was measured), the time until cracking occurred was increased by 48 hours (see Comparative Example 3 and Reference Example 4 described below). In contrast, when a similar test was performed using titanium oxide substituted with a non-tetravalent transition metal element, the time until cracking occurred was increased by 336 hours, demonstrating an approximately seven-fold difference in the effect of adding HALS. Furthermore, when compared with HALS that uses titanium oxide substituted with a transition metal element other than tetravalent and contains no OH but one or two N atoms (see Comparative Examples 1 and 2 and Reference Example 1 described below), the time until cracks appear is only increased by a maximum of 48 hours. Thus, a remarkable effect was confirmed when titanium oxide substituted with a transition metal element other than tetravalent is used and HALS has a molecular structure containing OH and three or more N atoms.

[0011] The present invention relates to a coating composition containing titanium oxide and HALS, wherein the titanium oxide is substituted with a transition metal element other than tetravalent, and the molecular structure of the HALS comprises OH and three or more N. The coating composition of the present invention will be described in detail below.

[0012] [Titanium oxide] The titanium oxide contained in the coating composition of the present invention includes titanium oxide substituted with a non-tetravalent transition metal element. In the present invention, titanium oxide substituted with a non-tetravalent transition metal element refers to titanium oxide in which a portion of the crystal structure has been substituted with a non-tetravalent transition metal element, and is a substitutional solid solution. Whether a non-tetravalent transition metal element has been substituted can be determined by (i) whether a composition analysis shows the presence of transition metal elements other than Ti and O (excluding tetravalent elements), and (ii) whether an X-ray diffraction pattern obtained by X-ray diffraction measurement shows the absence of peaks other than those attributable to the titanium oxide crystal structure. Known crystal structures of titanium oxide include anatase, rutile, and brookite. When forming coating films for optical applications, the crystal structure of titanium oxide is preferably rutile, which tends to have a high refractive index. Furthermore, rutile is preferable in terms of the weather resistance of titanium oxide.

[0013] The titanium oxide contained in the coating composition of the present invention is preferably substituted with at least one non-tetravalent transition metal element selected from Cr, Mn, Fe, Co, Ni, Cu, Nb, Mo, W, and Ce, and more preferably at least one selected from Fe, Ni, Mo, and Mn. The use of titanium oxide substituted with such a non-tetravalent transition metal element can further improve the weather resistance of the coating film. The molar ratio of the non-tetravalent transition metal element (M) to Ti (M / (Ti+M)) is preferably 0.0001 to 5, more preferably 0.001 to 3, and particularly preferably 0.001 to 1. A molar ratio within these ranges is preferred because it tends to improve the weather resistance of the coating film and reduce coloration.

[0014] The titanium oxide contained in the coating composition of the present invention may contain a tetravalent element other than Ti. Specifically, it preferably contains at least one selected from Si, Zr, and Sn. These elements may be substituted into titanium oxide or may exist as a coating layer on the surface. When at least one of Si and Zr is contained, the weather resistance of the coating film is improved. When the titanium oxide has a rutile crystal structure, the presence of Sn suppresses the formation of other crystal structures. Furthermore, elements other than tetravalent elements are more likely to be substituted into titanium oxide, resulting in increased crystallinity of titanium oxide containing elements other than tetravalent elements. The tetravalent elements other than Ti are preferably contained in a range of 1% by mass to 60% by mass, more preferably 10% by mass to 55% by mass, and particularly preferably 20% by mass to 50% by mass, calculated as metal oxide, relative to the mass of titanium oxide.

[0015] The titanium oxide contained in the coating composition of the present invention may contain a non-tetravalent transition metal element. Specifically, it may contain at least one element selected from Sb, Zn, Al, Mg, Na, and K. When a non-tetravalent transition metal element and at least one element selected from Sb, Zn, Al, Mg, and K are substituted on the titanium oxide, weather resistance is further improved. The content of the non-tetravalent transition metal element is preferably in the range of 0.01% by mass or more and 5% by mass or less, based on the mass of the titanium oxide.

[0016] The titanium oxide contained in the coating composition of the present invention preferably has a coating layer formed on its surface. For example, if a coating layer containing elements such as Zr, Si, and Al is formed, the weather resistance of the coating film will be improved. In particular, if a coating layer containing at least one element selected from Si and Zr is formed, the coating film will tend to have good dispersibility in water or polar solvents such as alcohol.

[0017] The titanium oxide of the present invention can also be used whose surface has been surface-modified with an organosilicon compound.When the surface has been modified with an organosilicon compound, when the titanium oxide is prepared into a dispersion liquid or a coating liquid for forming a coating film as described below, the dispersibility in the resin or organic solvent components contained in the liquid is increased.In addition, when a coating layer is formed on the surface of the titanium oxide particles of the present invention, the surface of the coating layer may be surface-modified with an organosilicon compound.

[0018] The average particle size of the titanium oxide contained in the coating composition of the present invention is preferably in the range of 5 nm to 50 nm, more preferably in the range of 10 nm to 30 nm. By using titanium oxide of such a size, the titanium oxide is easily dispersed uniformly in the coating material and a dense coating film is easily formed. In the present invention, the average particle size value is obtained by measuring the sizes of multiple primary particles using an electron microscope and averaging the measurements.

[0019] The content of titanium oxide in the coating composition of the present invention may be in the range of 0.01% by mass to 50% by mass, or in the range of 0.1% by mass to 40% by mass, or in the range of 1% by mass to 30% by mass, relative to the mass of the coating composition. By including titanium oxide in such a range, the titanium oxide is more likely to be dispersed uniformly in the coating material, and a dense coating film is more likely to be formed.

[0020] [Hindered amine light stabilizers] The HALS contained in the coating composition of the present invention has a molecular structure comprising OH and three or more N atoms. An example of a HALS with such a molecular structure is 2,4-bis[N-butyl-N-(1-cyclohexyloxy-2,2,6,6-tetramethylpiperidin-4-yl)amino]-6-(2-hydroxyethylamine)-1,3,5-triazine. Combining such a HALS with titanium dioxide substituted with a transition metal element other than tetravalent significantly improves the weather resistance of the coating film. Furthermore, the coating film exhibits improved haze compared to other HALS, and this effect is more pronounced in exposure tests using a weathering tester (Q-Lab: QUV ultraviolet fluorescent lamp accelerated weathering tester) (see Table 3 below).

[0021] The melting point of the HALS contained in the coating composition of the present invention is preferably in the range of 20° C. to 100° C., more preferably in the range of 50° C. to 100° C. By using a HALS that is solid at the temperature of the coating film's operating environment, bleeding of the HALS (precipitation onto the coating film surface) is suppressed, and the coating film becomes more stable and weather-resistant.

[0022] The HALS content in the coating composition of the present invention, expressed as the mass ratio of HALS to titanium oxide (HALS / titanium oxide), is preferably in the range of 0.001 to 0.3, more preferably 0.0015 to 0.25, and particularly preferably 0.002 to 0.2. By including HALS in such a range, the weather resistance of the coating film is improved.

[0023] [solvent] The coating composition of the present invention contains a solvent in addition to titanium dioxide and HALS. The solvent may be water or an organic solvent. It may also be a mixed solvent of water and an organic solvent. In particular, when the coating composition contains a hydrolyzable matrix component, a mixed solvent of water and a solvent is preferred.

[0024] Examples of organic solvents that can be used in the coating composition of the present invention include: Alcohols such as methanol, ethanol, ethylene glycol, 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 gamma-butyrolactone; ethers such as diethyl ether, ethylene glycol monomethyl ether (methyl cellosolve), ethylene glycol monoethyl ether (ethyl cellosolve), ethylene glycol monobutyl ether (butyl cellosolve), propylene glycol monomethyl ether, propylene glycol monoethyl ether, diethylene glycol monomethyl ether, and diethylene glycol monoethyl ether; Ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, acetylacetone, diacetone alcohol and cyclohexanone; aromatic hydrocarbons such as benzene, toluene, xylene, and ethylbenzene; Cyclic hydrocarbons such as cyclohexane; and Examples of the organic solvent include amides such as dimethylformamide, N,N-dimethylacetoacetamide, and N-methylpyrrolidone. These organic solvents may be used alone or in combination of two or more. The content of the solvent may be in the range of 50% by mass or more and 90% by mass or less, based on the mass of the coating composition.

[0025] [Other ingredients] The coating composition of the present invention may contain a matrix-forming component, a leveling agent, a curing catalyst, an antioxidant, a UV absorber, a dye, a pigment, or the like.

[0026] The coating composition of the present invention may contain a matrix-forming component, which may be any matrix-forming component used in a typical coating solution for forming a coating film. Examples include tetramethoxysilane, tetraethoxysilane, 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. The content of the matrix-forming component, expressed as the mass ratio of the matrix-forming component to titanium oxide (matrix-forming component / titanium oxide), is preferably in the range of 0.5 to 5, more preferably in the range of 0.7 to 3, and particularly preferably in the range of 1 to 2.5.

[0027] The coating composition of the present invention may contain a leveling agent. For example, a silicone surfactant such as polyoxyalkylene dimethyl polysiloxane, a perfluoroalkyl carboxylate, or a fluorine-containing surfactant such as a perfluoroalkyl ethylene oxide adduct may be contained, and a silicone surfactant is particularly preferred. The content of the leveling agent may be in the range of 0.001% by mass or more and 1% by mass or less relative to the mass of the coating composition.

[0028] The coating composition of the present invention may contain a heat-curing catalyst as a curing catalyst. Examples of such catalysts include amines such as n-butylamine, triethylamine, guanidine, and biguanidide; 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 octoate, and tin octoate; perchloric acids or salts thereof such as perchloric acid, ammonium perchlorate, and magnesium perchlorate; acids such as hydrochloric acid, phosphoric acid, nitric acid, and paratoluenesulfonic acid; and metal chlorides that are Lewis acids such as SnCl2, AlCl3, FeCl3, TiCl4, ZnCl2, and SbCl3. These may be used alone or in combination.

[0029] The coating composition of the present invention may contain a photocuring catalyst as a curing catalyst. For example, bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide, bis(2,6-dimethoxybenzoyl)-2,4,4-trimethylpentylphosphine oxide, 2-hydroxymethyl-2-methylphenylpropane-1-ketone, 2,2-dimethoxy-1,2-diphenylethan-1-one, 1-hydroxycyclohexylphenylketone, and 2-methyl-1-[4-(methylthio)phenyl]-2-morpholinopropan-1-one may be used. These may be used alone or in combination of two or more. The content of the curing catalyst may be in the range of 0.01% by mass or more and 2% by mass or less relative to the mass of the coating composition.

[0030] [Coated substrate] The coating composition of the present invention can be used to form a coating film on various substrates such as glass or plastic to produce a coated substrate. This coated substrate can be used as an optical substrate for eyeglass lenses, various optical lenses for cameras, etc., front panels for optical displays, show window cases, window glass, contact glass for copiers, automotive light covers, and various ultraviolet ray blocking filters.

[0031] [Method of manufacturing the coating composition of the present invention] The coating composition of the present invention can be prepared, for example, by a production method comprising the following steps (1) and (2). However, the production method for the coating composition of the present invention is not limited to the following production method. (1) Preparation of titanium oxide substituted with a transition metal element other than tetravalent (2) Painting process The method for preparing the coating composition of the present invention will be described in detail below.

[0032] [(1) Preparation of titanium oxide substituted with elements other than tetravalent elements] In this step, for example, a preparation method including the following steps (a) to (c) can be used to prepare titanium oxide substituted with an element other than tetravalent elements.

[0033] (A) Coprecipitation gel preparation process In this process, an acidic aqueous solution containing Ti and non-tetravalent transition metal elements is neutralized with an alkaline aqueous solution to prepare a coprecipitated gel. Preparing this coprecipitated gel further promotes the substitution of non-tetravalent transition metal elements into the final titanium oxide. The acidic aqueous solution can be prepared by dissolving a Ti source and a compound containing a non-tetravalent transition metal element in water. Conventional Ti sources, such as titanium tetrachloride, titanium sulfate, and titanium alkoxides, can be used. Conventional compounds containing non-tetravalent transition metal elements, such as chlorides, sulfates, nitrates, and acetates, can be used. Alternatively, an oxide containing a non-tetravalent transition metal element can be dissolved in acid and used as the raw material. The pH of the acidic aqueous solution is preferably 4 or less, more preferably 3 or less, and particularly preferably 2 or less. A low pH facilitates the dissolution and dispersion of Ti and non-tetravalent transition metal elements in the acidic aqueous solution, thereby facilitating the substitution of non-tetravalent transition metal elements into the final titanium oxide. The Ti content of the acidic aqueous solution can be appropriately adjusted to a level that does not visually detect solid precipitation. The content of the non-tetravalent transition metal element in the acidic aqueous solution may be adjusted appropriately to match the amount of the element to be substituted, taking into account the Ti content. Elements other than the non-tetravalent transition metal element may also be added here.

[0034] The alkaline aqueous solution can be prepared by dissolving an alkaline source in water. Conventional known raw materials such as sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, or ammonia can be used as the alkaline source. The pH of the alkaline aqueous solution may be 10 or higher, 11 or higher, or 12 or higher. The alkaline aqueous solution may be adjusted so that the pH is in the range of 4 or higher to 10 or lower when mixed with the acidic aqueous solution. Mixing the acidic aqueous solution and the alkaline aqueous solution produces a coprecipitated gel containing Ti and transition metal elements other than tetravalent elements. This coprecipitated gel can be recovered by filtration and, if necessary, washed with water or the like.

[0035] (a) Hydrothermal treatment precursor preparation step In this step, the coprecipitated gel obtained in the previous step is redispersed (deflocculated) in water to prepare a hydrothermal treatment precursor.

[0036] The coprecipitated gel can be peptized by any conventional method. For example, the coprecipitated gel can be dispersed in water and subjected to ultrasonic treatment, or dispersed in water using an acid or alkali. Peptization can also be performed using aqueous hydrogen peroxide. In this case, it is preferable to adjust the amount of water so that the solids concentration in the final hydrothermal treatment precursor is 10% by mass or less.

[0037] The average particle size of the particles contained in the hydrothermal treatment precursor obtained in this step is preferably in the range of 5 nm to 50 nm, more preferably in the range of 10 nm to 40 nm, and particularly preferably in the range of 15 nm to 30 nm. As the average particle size of the particles contained in the hydrothermal treatment precursor increases, the average particle size of the titanium oxide finally obtained tends to increase. Therefore, it is preferable to adjust the average particle size of the particles contained in the hydrothermal treatment precursor so that it is close to the average particle size of the titanium oxide finally desired to be prepared.

[0038] In this step, after peptizing the coprecipitated gel, a raw material containing an element other than a non-tetravalent transition metal element may be added. The raw material containing an element other than a non-tetravalent transition metal element is preferably a water-soluble raw material. If the raw material is not water-soluble, the raw material is preferably dispersed in a sol state. In this case, if a salt containing an alkali metal or alkaline earth metal is used as the raw material, it is preferable to dissolve the raw material and then remove the alkali metal or alkaline earth metal using a cation exchange resin or the like.

[0039] (c) Hydrothermal treatment process In this step, the hydrothermal treatment precursor obtained in the previous step is hydrothermally treated to prepare titanium oxide substituted with a transition metal element other than tetravalent.

[0040] In this step, the hydrothermal treatment precursor can be hydrothermally treated using conventional equipment such as an autoclave. The temperature of the hydrothermal treatment is preferably in the range of 100°C to 250°C, more preferably in the range of 120°C to 220°C, and particularly preferably in the range of 130°C to 210°C. The retention time in the above temperature range is preferably in the range of 1 hour to 48 hours, more preferably in the range of 5 hours to 24 hours, and particularly preferably in the range of 10 hours to 20 hours.

[0041] Titanium oxide is contained in the reaction solution after the hydrothermal treatment, and may be separated, washed, etc., if necessary. The separated titanium oxide may also be calcined to enhance its crystallinity.

[0042] When a coating layer is formed on the surface of titanium oxide, it can be formed, for example, by the method described in JP 2009-155496 A. When titanium oxide is dispersed in an organic solvent or a solution in which a resin is dispersed, the surface or the surface of the coating layer can be hydrophobized (surface treated) using the method described in the same publication.

[0043] [(2) Painting process] In this step, the titanium oxide obtained in step (1) is dispersed in a solvent, and then a HALS having a molecular structure containing OH and three or more N atoms is added to prepare a coating composition. If the titanium oxide obtained in step (1) is in powder form, it can be added to water or an organic solvent, and then subjected to a dispersion treatment such as bead milling or ultrasonic treatment. In this case, if the titanium oxide concentration in the coating composition is 10% by mass or less, titanium oxide can be more easily dispersed in the solvent. In addition, the zeta potential of titanium oxide can be measured, and the pH can be adjusted to a range suitable for dispersion. The solvent may be water or an organic solvent. It may also be a mixed solvent of water and an organic solvent. In particular, when a hydrolyzable matrix-forming component is contained in the coating composition, a mixed solvent of water and a solvent is preferable.

[0044] The organic solvents that can be used in this step are the organic solvents described above.

[0045] In this step, a matrix-forming component, a leveling agent, a curing catalyst, an antioxidant, a UV absorber, a dye, or a pigment may be added, if necessary.

[0046] The matrix-forming components that can be used in this step are the matrix-forming components described above. The leveling agent that can be used in this step is the leveling agent described above. The curing catalyst that can be used in this step is the above-mentioned photocuring catalyst or the above-mentioned heat curing catalyst.

[0047] [Method for forming a coating film using the coating composition of the present invention] A coating film can be formed by a conventionally known method using the coating composition of the present invention and a substrate.

[0048] Examples of the substrate include various substrates made of glass or plastic, and specific examples include plastic substrates used for optical lenses. The thickness of the coating film formed on the substrate varies depending on the application of the coated substrate, but is preferably 0.03 μm or more and 30 μm or less.

[0049] The coating film can be prepared by applying the coating composition of the present invention to a substrate by a conventionally known method such as dipping, spraying, spinning, roll coating, or bar coating, followed by drying and curing by heat treatment or ultraviolet irradiation, etc. When forming the coating film, the surface of the substrate, for example a plastic substrate, may be previously treated with an alkali, acid, or surfactant, polished with inorganic or organic fine particles, or treated with a primer or plasma, in order to improve adhesion between the substrate and the coating film. [Example]

[0050] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples. [Measurement method or evaluation method] The various measurements and evaluations were carried out as follows.

[0051] [1] Average particle size The shape of the measurement sample was observed using a scanning electron microscope (SEM) (Hitachi High-Technologies Corporation, S-5500) at an accelerating voltage of 30 kV. The observation sample was prepared as follows: The measurement sample was diluted with water to a solids concentration of 0.05% by mass, then applied to a metal grid with a collodion film (Oken Shoji Co., Ltd.), and irradiated with a 250 W infrared lamp to evaporate the solvent, preparing the observation sample. The obtained SEM image was printed, and the particle diameters of 100 primary particles were measured with a vernier caliper, and the average value was taken as the average particle diameter. Note that if the particle shape was anisotropic, the major axis was taken as the particle diameter.

[0052] [2] Solid content concentration The solvent contained in the measurement sample was removed by infrared irradiation or the like, and the residue was then calcined at 1000°C for 1 hour to obtain the ignition residue (solid content). The ratio of the mass of the ignition residue to the mass of the measurement sample was taken as the solid content concentration.

[0053] [3] Composition measurement method (titanium, tin, silicon, iron and antimony) The aqueous dispersion of the measurement sample was collected in a zirconia ball and the water was removed by infrared irradiation. The dried product was then mixed with Na2O2 and NaOH and heated to melt. Sulfuric acid and hydrochloric acid were then added to the melt, followed by water for dilution. Using an ICP device (Shimadzu Corporation, ICPS-8100), the amounts of titanium, tin, silicon, iron, and antimony in the resulting solution were measured in terms of oxides (TiO2, SnO2, SiO2, Fe2O3, and Sb2O5).

[0054] (nickel, zirconium, and aluminum) The aqueous dispersion of the measurement sample was placed on a platinum dish, and after adding hydrofluoric acid and sulfuric acid and heating, water was added to dissolve the solids contained in the measurement sample. After diluting the sample with water, the amounts of nickel, zirconium, and aluminum were measured in terms of oxides (NiO, ZrO2, and Al2O3) using an ICP device (Shimadzu Corporation, ICPS-8100).

[0055] (potassium) The aqueous dispersion of the measurement sample was placed on a platinum dish, and hydrofluoric acid and sulfuric acid were added and heated. Hydrochloric acid was then added to dissolve the solids. After diluting with water, the amount of potassium was measured in terms of oxide (KO) using an atomic absorption spectrometer (Hitachi, Ltd., Z-5300).

[0056] (Method of calculating composition) Based on each measurement result, the composition of each element converted to oxide was calculated, with the mass of the solid content contained in the measurement sample being 100%. The oxide was identified based on the valence of each element. This valence is based on the valence of the compound that is the raw material for each element.

[0057] [4] Crystal structure analysis of particles A 2 g solids weight of the aqueous dispersion of the measurement sample was placed in a porcelain crucible (B-2 type) and dried at 110 °C for 12 hours. The residue was then placed in a desiccator and cooled to room temperature. Powder X-ray diffraction was then measured using a SmartLab X-ray diffractometer (Rigaku Corporation). Peak positions were identified for the obtained diffraction pattern using PDXL2 version 2.7.2.0 software. The measurement conditions and data analysis details are as follows: Measurement conditions Measurement equipment: Powder X-ray diffraction measurement equipment SmartLab (manufactured by Rigaku Corporation) X-ray generator: 9kW open tube (CuKα source, voltage 45kV, current 200mA) Soller / PSC: 5.0 deg IS length: 10.0 mm PSA: None Soller: 5.0 deg IS:1 / 2 RS1: 13mm RS2: 20mm Scan step: 0.02deg Scan range: 5-70deg Scan speed: 5deg / min X-ray detector: High-speed one-dimensional X-ray detector (D / TeX Ultra 250) Measurement atmosphere: Atmospheric Sample stage: Al2O3 sample holder (bottomless) Data analysis Analysis software: Integrated powder X-ray analysis software PDXL2 Version 2.7.2.0 (Rigaku Corporation) Smoothing: B-Splne smoothing (X threshold 1.5) Background removal: fitting method Kα2 removal: intensity ratio 0.497 Peak search: Second-order differential method, σ cut value = 3, σ cut range 0.5 to 20.0 Profile fitting method: Fitting to measurement data Profile fitting Peak shape: Split pseudo-Voigt function

[0058] [5] Coating evaluation The required number of commercially available plastic lens substrates with a refractive index of 1.60 ("Monomer name: MR-8" manufactured by Mitsui Chemicals, Inc.) were prepared and etched by immersing them in an 8% by mass aqueous NaOH solution kept at 40°C for 10 minutes. They were then removed, washed with water, and thoroughly dried.

[0059] A coating composition was applied to the surface of the plastic lens substrate obtained in the above process to form a coating film. This coating composition was applied using a spin coating method, and the conditions were adjusted so that the film thickness after curing would be 2.5 μm. The coating film was cured by heat treatment at 80°C for 10 minutes and then at 120°C for 1 hour to obtain a substrate with a coating film.

[0060] [5-1] Evaluation method for the appearance (cloudiness) of the coating film In an environment of 10 lux or less, fluorescent lamps "Product name: Mellow 5N" (manufactured by Toshiba Lighting & Technology Corporation, three-wavelength daylight fluorescent lamp) and "Product name: Sunwhite 5" (manufactured by NEC Corporation, general-purpose white fluorescent lamp) were installed, and the substrate with the coating was placed vertically directly under the fluorescent lamp. The transparency (degree of cloudiness) of these was visually confirmed and evaluated according to the following criteria.

[0061] 5: When checked under a three-wavelength daylight fluorescent lamp, no cloudiness was observed. 4: When viewed under a three-wavelength daylight fluorescent lamp, there is some cloudiness. 3: When checked under a three-wavelength daylight fluorescent lamp, cloudiness can be seen. 2: When viewed under a three-wavelength daylight fluorescent lamp, it is quite cloudy. 1: Clouding can be seen even with standard white fluorescent lamps.

[0062] [5-2] Weather resistance evaluation method for coating films Weather resistance evaluation method for coating film (cracking) The coated substrate was subjected to a weathering test using a weathering tester (Q-Lab's QUV ultraviolet fluorescent lamp accelerated weathering tester) to evaluate the time until cracks were visually observed. The weathering test consisted of the following steps 1, 2, and 3, which constituted one cycle (12 hours), and the presence or absence of cracks was visually observed every two cycles (24 hours). [Weather resistance test conditions] Step 1: UV irradiation (light source: UVA-340, radiation intensity: 0.70 W / m 2 , Temperature: 60℃, Time: 8 hours) Step 2: Condensation (light source: none, temperature: 50°C, time: 4 hours) · Step 3: Return to step 1. [Evaluation method] Environment: 10 lux or less Observation method: The substrate with the heat-cured coating was irradiated with an LED light from the side and visually inspected for cracks.

[0063] [5-3] Weather resistance evaluation method for coating film (appearance of coating film (cloudiness)) In the weather resistance test, the appearance (cloudiness) of the coating film was evaluated in the same manner as in the evaluation of the appearance (cloudiness) of the coating film at the end of four cycles (48 hours).

[0064] [Preparation of titanium oxide A] An acidic aqueous solution was prepared by mixing 668 g of a titanium tetrachloride aqueous solution (Osaka Titanium Technologies Co., Ltd.) containing 7.75 mass% Ti in terms of TiO2 with 5.37 g of an aqueous solution of nickel(II) chloride hexahydrate (Kanto Chemical Co., Ltd.) containing 7.75 mass% Ni in terms of NiO. Next, ammonia water (Ube Industries, Ltd.) containing 15 mass% ammonia was prepared and used as an alkaline aqueous solution. This acidic aqueous solution and alkaline aqueous solution were mixed to prepare a slurry with a pH of 9.5. The solids were filtered from this slurry and then washed with water to obtain 520 g of coprecipitated gel A with a solids concentration of 10 mass%.

[0065] To 202 g of this coprecipitated gel A, 347 g of hydrogen peroxide solution (manufactured by Mitsubishi Gas Chemical Co., Inc.) containing 35% by mass of hydrogen peroxide and 1,145 g of water were added, followed by stirring at 80°C for 1 hour. Next, 328 g of water was added to obtain 2,020 g of deflocculating solution A with a solids concentration of 1% by mass. This deflocculating solution A was transparent and had a pH of 8.5. The average particle size of the particles contained in this deflocculating solution A was 25 nm.

[0066] This deflocculating solution A (2020 g) was mixed with a cation exchange resin (manufactured by Mitsubishi Chemical Corporation), and then 273 g of a potassium stannate aqueous solution containing 1% by mass of Sn in terms of SnO2 (prepared by dissolving potassium stannate, manufactured by Showa Kako Co., Ltd., in water) was gradually added while stirring. After the addition of the potassium stannate aqueous solution was completed, the cation exchange resin was separated, and silica sol containing 0.4% by mass of aluminum in terms of Al2O3 (average particle diameter 16 nm (value obtained using dynamic scattering method), specific surface area 375 m) was obtained. 2 Hydrothermal treatment precursor A was prepared by adding 32.5 g of silica sol (prepared with reference to the method described in Example 1 "Preparation of silica sol" in JP-A No. 2009-197078, having a pH of 2.2 and a solid content of 16% by mass) and 508 g of water.

[0067] This hydrothermal treatment precursor A was heated at 165°C for 18 hours in an autoclave (Taiatsu Glass Industries Co., Ltd., 5 L). The autoclave was cooled to room temperature, and a sol-like reaction product was recovered. The reaction product was concentrated using an ultrafiltration membrane device (Asahi Kasei Corporation, SIP-1013, SIP-0013) to obtain 270 g of core particle dispersion A with a solids concentration of 10% by mass.

[0068] The particles contained in this core particle dispersion A were titanium oxide (core particles A) having a rutile crystal structure. The composition of these core particles A is shown in Table 1.

[0069] 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 Zr in terms of ZrO2 while stirring to obtain a slurry 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 Zr in terms of ZrO2.

[0070] 180 g of water was added to 20 g of this zirconia cake, and 4.0 g of potassium hydroxide granules containing 85 mass% potassium hydroxide (Kanto Chemical Co., Inc.) was added to make the system alkaline. 40 g of hydrogen peroxide solution containing 35 mass% hydrogen peroxide was then added, and the mixture was heated to 50°C to dissolve the zirconia cake. 156 g of water was then added to obtain 400 g of aqueous zirconium peroxide solution A containing 0.5 mass% Zr in terms of ZrO2. The pH of this aqueous zirconium peroxide solution A was 12.9.

[0071] 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 a silicic acid aqueous solution A containing 2 mass % of Si in terms of SiO2.

[0072] Water was added to the core particle dispersion A to prepare 1,350 g of a dispersion with a solid content of 2% by mass. After heating this dispersion to 90°C, 328 g of the zirconium peroxide aqueous solution A and 254 g of the silicic acid aqueous solution A were gradually added, and after the addition was completed, the mixture was aged for 1 hour with stirring while maintaining the temperature at 90°C.

[0073] The aged mixture was placed in a high-pressure reactor (HU-100, manufactured by San-Ai Chemical Co., Ltd.) and heated at 165°C for 18 hours. The mixture was then concentrated using an ultrafiltration membrane device (SIP-0013, manufactured by Asahi Kasei Co., Ltd.) to a solids concentration of 10%. In this way, coated particle dispersion A was obtained.

[0074] A methanol solution containing 17.1 g of tetraethoxysilane (Tama Chemicals Co., Ltd.) as a surface treatment agent was prepared, and 216 g of the coated particle dispersion A was added to this solution with stirring. The resulting mixture was then heated to 50°C for 6 hours, cooled to room temperature, and the dispersion medium in the mixture was replaced from water to methanol using an ultrafiltration membrane device (Asahi Kasei Corporation, SIP-0013). The mixture was then further concentrated to obtain methanol dispersion A with a solids concentration of 20.6% by mass. The titanium oxide contained in this methanol dispersion A was designated titanium oxide A, and its composition, physical properties, and evaluation results are shown in Table 1.

[0075] [Preparation of titanium oxide B] An acidic aqueous solution was prepared by mixing 668 g of a titanium tetrachloride aqueous solution (Osaka Titanium Technologies Co., Ltd.) containing 7.75 mass% Ti in terms of TiO2, 6.03 g of an aqueous solution of ferric chloride (Toagosei Co., Ltd., high-grade superferrous iron) containing 7.75 mass% Fe in terms of Fe2O3, and 54.7 g of zirconium oxychloride (Taiyo Koko Co., Ltd.) containing 7.75 mass% Zr in terms of ZrO2. Next, ammonia water (Ube Industries, Ltd.) containing 15 mass% ammonia was prepared and used as an alkaline aqueous solution. This acidic aqueous solution and alkaline aqueous solution were mixed to prepare a slurry with a pH of 9.5. The solids were filtered from this slurry and then washed with water to obtain 560 g of coprecipitated gel B with a solids concentration of 10 mass%.

[0076] 270 g of core particle dispersion B having a solid content of 10 mass % was obtained using the same method as in Example 1, except that coprecipitated gel B was used instead of coprecipitated gel A. The particles contained in this core particle dispersion B were titanium oxide (core particles B) having a rutile crystal structure. The composition of this core particle B is shown in Table 1.

[0077] Water was added to the core particle dispersion B to prepare 700 g of a dispersion with a solids concentration of 2% by mass. To this dispersion, 196 g of aqueous zirconium peroxide solution A obtained in the same manner as in Example 1 was added with stirring at room temperature, followed by heat treatment at 60°C for 6 hours. This was diluted with water to a solids concentration of 0.1% by mass, and then subjected to hydrothermal treatment in an autoclave at 165°C for 18 hours. The reaction product was removed and concentrated using an ultrafiltration membrane device (manufactured by Asahi Kasei Corporation, SIP-1013, SIP-0013) to obtain 145 g of coated particle dispersion B with a solids concentration of 10% by mass.

[0078] A methanol solution containing 17.1 g of tetraethoxysilane (Tama Chemicals Co., Ltd.) as a surface treatment agent was prepared, and 140 g of the coated particle dispersion B was added to this solution with stirring. The resulting mixture was then heated to 50°C for 6 hours, cooled to room temperature, and the dispersion medium in the mixture was replaced from water to methanol using an ultrafiltration membrane device (Asahi Kasei Corporation, SIP-0013). The mixture was then further concentrated to obtain methanol dispersion B with a solids concentration of 20.5% by mass. The titanium oxide contained in this methanol dispersion B was designated titanium oxide B, and its composition, physical properties, and evaluation results are shown in Table 1.

[0079] [Preparation of titanium dioxide C] An acidic aqueous solution was prepared by mixing 668 g of a titanium tetrachloride aqueous solution (Osaka Titanium Technologies Co., Ltd.) containing 7.75% by mass of Ti in terms of TiO2, 6.03 g of an aqueous solution of ferric chloride (Toa Gosei Co., Ltd., high-grade superferric) containing 7.75% by mass of Fe in terms of Fe2O3, and 4.14 g of antimony(III) chloride (Fujifilm Wako Co., Ltd.). Next, ammonia water (Ube Industries, Ltd.) containing 15% by mass of ammonia was prepared and used as an alkaline aqueous solution. This acidic aqueous solution and alkaline aqueous solution were mixed to prepare a slurry with a pH of 9.5. The solids were filtered from this slurry and then washed with water to obtain 560 g of coprecipitated gel C with a solids concentration of 10% by mass.

[0080] Using the same method as in Example 1, except that coprecipitated gel C was used instead of coprecipitated gel A, 270 g of core particle dispersion C with a solid content of 10 mass % was obtained. The particles contained in this core particle dispersion C were titanium oxide (core particles C) having a rutile crystal structure. The composition of this core particle C is shown in Table 1.

[0081] Water was added to the core particles C to prepare 700 g of a dispersion with a solids concentration of 2% by mass. To this dispersion, 196 g of aqueous zirconium peroxide solution A obtained in the same manner as in Example 1 was added with stirring at room temperature, followed by heat treatment at 60°C for 6 hours. The resulting mixture was diluted with water to a solids concentration of 0.1% by mass, and then subjected to hydrothermal treatment in an autoclave at 165°C for 18 hours. The reaction product was removed and concentrated using an ultrafiltration membrane device (manufactured by Asahi Kasei Corporation, SIP-1013, SIP-0013) to obtain 145 g of a coated particle dispersion C with a solids concentration of 10% by mass.

[0082] A methanol solution containing 17.1 g of tetraethoxysilane (Tama Chemicals Co., Ltd.) as a surface treatment agent was prepared, and 140 g of the coated particle dispersion C was added to this solution with stirring. The resulting mixture was then heated to 50°C for 6 hours, cooled to room temperature, and the dispersion medium in the mixture was replaced from water to methanol using an ultrafiltration membrane device (Asahi Kasei Corporation, SIP-0013). The mixture was then further concentrated to obtain methanol dispersion C with a solids concentration of 21.1% by mass. The titanium oxide contained in this methanol dispersion C was designated titanium oxide C, and its composition, physical properties, and evaluation results are shown in Table 1.

[0083] [Preparation of titanium oxide D] 937 g of a titanium tetrachloride aqueous solution (manufactured by Osaka Titanium Technologies Co., Ltd.) containing 7.75 mass% Ti in terms of TiO2 was prepared, and this was used as an acidic aqueous solution. Next, ammonia water (manufactured by Ube Industries, Ltd.) containing 15 mass% ammonia was prepared, and this was used as an alkaline aqueous solution. This acidic aqueous solution and alkaline aqueous solution were mixed to prepare a slurry with a pH of 9.5. After filtering the solid content from this slurry, the solid content was washed with water to obtain 720 g of a hydrous titanic acid cake with a solid content concentration of 10 mass%.

[0084] 270 g of core particle dispersion D having a solids concentration of 10 mass % was obtained in the same manner as in Example 1, except that the hydrous titanate cake was used instead of coprecipitated gel A. The particles contained in this core particle dispersion D were titanium oxide having a rutile crystal structure (core particles D). The composition of this core particle D is shown in Table 1.

[0085] Next, using the same method as in Example 1, except that core particle dispersion D was used instead of core particle dispersion A, and 91.8 g of zirconium peroxide aqueous solution A and 71.1 g of silicic acid aqueous solution A were used, coated particle dispersion D with a solid content concentration of 10 mass % was obtained.

[0086] A methanol solution containing 10.7 g of tetraethoxysilane (Tama Chemicals Co., Ltd.) as a surface treatment agent was prepared, and 135 g of the coated particle dispersion D was added to this while stirring. The resulting mixture was then heated to 50°C for 6 hours, cooled to room temperature, and the dispersion medium in the mixture was replaced from water to methanol using an ultrafiltration membrane device (Asahi Kasei Corporation, SIP-0013). The mixture was then further concentrated to obtain methanol dispersion D with a solids concentration of 30.6% by mass. The titanium oxide contained in this methanol dispersion C was designated titanium oxide D, and its composition, physical properties, and evaluation results are shown in Table 1.

[0087] Example 1: Titanium oxide A (Ni 2+ ) and HALS (8 N, 1 OH)] 21.654 g of the methanol dispersion A was stirred, and 6.046 g of purified water and γ-glycidoxypropyltrimethoxysilane (γ-GTS: manufactured by Momentive Performance Materials Japan, LLC; Silquest) were added as a matrix. TM 9.288 g of propylene glycol monomethyl ether (PGM: manufactured by Dow Chemical Co., Ltd.; Dowanol A-187J silane) was added to the mixture. The mixture was further stirred at room temperature for one hour to allow co-hydrolysis of the methanol dispersion A and γ-GTS. Next, propylene glycol monomethyl ether (PGM: manufactured by Dow Chemical Co., Ltd.; Dowanol A-187J silane) was added to the mixture. TM PM glycol ether), 0.220 g of acetylacetone aluminum (AcAcAl: Kishida Chemical) as a curing catalyst, and a silicone surfactant (DOWSIL TM 0.022 g of 2,4-bis[N-butyl-N-(1-cyclohexyloxy-2,2,6,6-tetramethylpiperidin-4-yl)amino]-6-(2-hydroxyethylamine)-1,3,5-triazine (BASF Tinuvin®) was added as a HALS. TM 152) 1.80 g of propylene glycol monomethyl ether (Dow Chemical: Dowanol TMHALS solution A was prepared by dissolving 0.078 g of HALS solution A in 16.20 g of PM glycol ether and stirring at room temperature for 1 hour. 0.078 g of HALS solution A was added to the coating composition and stirred at room temperature for 1 hour to obtain a coating composition containing HALS. The composition and physical properties of this coating composition containing HALS, as well as the results of evaluation, are shown in Table 2.

[0088] [Example 2: HALS content 0.13% by mass] A coating composition containing HALS was obtained in the same manner as in Example 1, except that the amount of HALS solution A added was 0.782 g. The composition and physical properties of this coating composition containing HALS, as well as the evaluation results, are shown in Tables 2 and 3.

[0089] [Example 3: HALS content 0.26% by mass] A coating composition containing HALS was obtained in the same manner as in Example 1, except that the amount of HALS solution A added was 1.565 g. The composition and physical properties of this coating composition containing HALS, as well as the evaluation results, are shown in Table 2.

[0090] [Example 4: HALS content 0.74% by mass] A coating composition containing HALS was obtained in the same manner as in Example 1, except that the amount of HALS solution A added was 4.694 g. The composition and physical properties of this coating composition containing HALS, as well as the evaluation results, are shown in Table 2.

[0091] [Example 5: HALS content 1.18% by mass] A coating composition containing HALS was obtained in the same manner as in Example 1, except that the amount of HALS solution A added was 7.823 g. The composition and physical properties of this coating composition containing HALS, as well as the evaluation results, are shown in Table 2.

[0092] Example 6: Titanium oxide B (Fe 2+ ) and HALS (8 N, 1 OH)] 19.914 g of the methanol dispersion B was stirred, and 6.331 g of purified water and γ-glycidoxypropyltrimethoxysilane (γ-GTS: manufactured by Momentive Performance Materials Japan, LLC; Silquest) were added as a matrix. TM 9.727 g of propylene glycol monomethyl ether (PGM: manufactured by Dow Chemical Co., Ltd.; Dowanol A-187J silane) was added to the mixture. The mixture was further stirred at room temperature for one hour to allow co-hydrolysis of the methanol dispersion B and γ-GTS. Next, propylene glycol monomethyl ether (PGM: manufactured by Dow Chemical Co., Ltd.; Dowanol A-187J silane) was added to the mixture. TM The mixture was mixed with 22.274 g of acetylacetone aluminum (AcAcAl: manufactured by Kishida Chemical) as a curing catalyst, and 0.230 g of silicone surfactant (manufactured by Dow Chemical) as a leveling agent. TM 0.023 g of 2,4-bis[N-butyl-N-(1-cyclohexyloxy-2,2,6,6-tetramethylpiperidin-4-yl)amino]-6-(2-hydroxyethylamine)-1,3,5-triazine (BASF Tinuvin®) was added as a HALS. TM 152) 1.80 g of propylene glycol monomethyl ether (Dow Chemical: Dowanol TM A HALS solution was prepared by dissolving 16.20 g of PM glycol ether in the paint composition and stirring at room temperature for 1 hour. 0.788 g of HALS solution A was added to the paint composition and stirred at room temperature for 1 hour to obtain a paint composition containing HALS. The composition and physical properties of this paint composition containing HALS, as well as the evaluation results, are shown in Table 2.

[0093] Example 7: Titanium oxide C (Fe 2+ , Sb 2+ ) and HALS (8 N, 1 OH)] 1.270 g of the methanol dispersion C2 was stirred, and 6.109 g of purified water and γ-glycidoxypropyltrimethoxysilane (γ-GTS: manufactured by Momentive Performance Materials Japan, LLC; Silquest) were added as a matrix. TM9.385 g of propylene glycol monomethyl ether (PGM: manufactured by Dow Chemical Co., Ltd.; Dowanol A-187J silane) was added to the mixture. The mixture was further stirred at room temperature for one hour to allow co-hydrolysis of the methanol dispersion C and γ-GTS. Next, propylene glycol monomethyl ether (PGM: manufactured by Dow Chemical Co., Ltd.; Dowanol A-187J silane) was added to the mixture. TM The mixture was mixed with 21.492 g of acetylacetone aluminum (AcAcAl: manufactured by Kishida Chemical) as a curing catalyst, and 0.222 g of silicone surfactant (Dow Chemical: manufactured by DOWSIL) as a leveling agent. TM 0.022 g of 2,4-bis[N-butyl-N-(1-cyclohexyloxy-2,2,6,6-tetramethylpiperidin-4-yl)amino]-6-(2-hydroxyethylamine)-1,3,5-triazine (BASF Tinuvin®) was added as a HALS. TM 152) 1.80 g of propylene glycol monomethyl ether (Dow Chemical: Dowanol TM A HALS solution was prepared by dissolving 16.20 g of PM glycol ether in the paint composition and stirring at room temperature for 1 hour. 0.783 g of HALS solution A was added to the paint composition and stirred at room temperature for 1 hour to obtain a paint composition containing HALS. The composition and physical properties of this paint composition containing HALS, as well as the results of evaluation, are shown in Table 2.

[0094] [Comparative Example 1: Titanium oxide A and HALS (1-2 N atoms, no OH group)] HALS: bis(1,2,2,6,6-pentamethyl-4-piperidinyl) sebacate, methyl(1,2,2,6,6-pentamethyl-4-piperidinyl) sebacate (BASF: Tinuvin TM 292) 1.80 g of propylene glycol monomethyl ether (Dow Chemical: Dowanol TMThe mixture was dissolved in 16.20 g of PM glycol ether and stirred at room temperature for 1 hour to prepare HALS solution B. A coating composition containing HALS was obtained in the same manner as in Example 2, except that HALS solution A was replaced with HALS solution B. The composition and physical properties of this coating composition containing HALS, as well as the evaluation results, are shown in Tables 2 and 3.

[0095] [Comparative Example 2: Titanium oxide A and HALS (N2, no OH)] As a HALS, decanedioic acid, bis(2,2,6,6-tetramethyl-1-(octyloxy)-4-piperidinyl) ester, 1,1-dimethylethyl hydroperoxide, and the reaction product with octane (EVERSORB manufactured by Eiko Chemical Co., Ltd.) were used. TM 95) 1.80 g of propylene glycol monomethyl ether (Dow Chemical: Dowanol TM HALS solution C was prepared by dissolving the HALS in 16.20 g of PM glycol ether and stirring at room temperature for 1 hour. A coating composition containing HALS was obtained in the same manner as in Example 2, except that HALS solution A was replaced with HALS solution C. The composition and physical properties of this coating composition containing HALS, as well as the evaluation results, are shown in Tables 2 and 3.

[0096] [Comparative Example 3: Titanium oxide D and HALS (8 N, 1 OH)] 13.288 g of the methanol dispersion D was stirred, and 6.566 g of methanol (Hayashi Pure Chemical Industries, Ltd.), 6.331 g of purified water, and γ-glycidoxypropyltrimethoxysilane (γ-GTS: Silquest, manufactured by Momentive Performance Materials Japan, LLC) were added as a matrix. TM 9.742 g of propylene glycol monomethyl ether (PGM: manufactured by Dow Chemical Co., Ltd.; Dowanol A-187J silane) was added to the mixture. The mixture was further stirred at room temperature for one hour to allow co-hydrolysis of the methanol dispersion D and γ-GTS. Next, propylene glycol monomethyl ether (PGM: manufactured by Dow Chemical Co., Ltd.; Dowanol A-187J silane) was added to the mixture. TMThe mixture was mixed with 22.309 g of PM glycol ether, 0.231 g of acetylacetone aluminum (AcAcAl: manufactured by Kishida Chemical) as a curing catalyst, and 0.231 g of silicone surfactant (manufactured by Dow Chemical) as a leveling agent. TM 0.023 g of HALS solution A (L-7001) was added, and the mixture was stirred at room temperature for one hour, and then allowed to stand at room temperature for 48 hours to obtain a coating composition. 0.788 g of HALS solution A was added to this coating composition to obtain a coating composition containing HALS. The composition and physical properties of this HALS-containing coating composition, as well as the evaluation results, are shown in Table 2.

[0097] [Reference Example 1: No titanium dioxide A or HALS] A coating composition was obtained in the same manner as in Example 1, except that HALS solution A was not added. The composition and physical properties of this coating composition, as well as the evaluation results, are shown in Tables 2 and 3.

[0098] [Reference Example 2: No titanium dioxide B or HALS] A coating composition was obtained in the same manner as in Example 6, except that HALS solution A was not added. The composition and physical properties of this coating composition, as well as the evaluation results, are shown in Table 2.

[0099] [Reference Example 3: No titanium dioxide or HALS] A coating composition was obtained in the same manner as in Example 7, except that HALS solution A was not added. The composition and physical properties of this coating composition, as well as the evaluation results, are shown in Table 2.

[0100] [Reference Example 4: No titanium dioxide D or HALS] A coating composition was obtained in the same manner as in Comparative Example 3, except that HALS solution A was not added. The composition and physical properties of this coating composition, as well as the evaluation results, are shown in Table 2.

[0101] [Table 1]

[0102] Table 2

[0103] Table 3

Claims

1. A coating composition comprising titanium oxide and a hindered amine light stabilizer, wherein the titanium oxide is substituted with a transition metal element other than a tetravalent element, and the hindered amine light stabilizer is 2,4-bis[N-butyl-N-(1-cyclohexyloxy-2,2,6,6-tetramethylpiperidin-4-yl)amino]-6-(2-hydroxyethylamine)-1,3,5-triazine.

2. 2. The coating composition according to claim 1, wherein the content of the hindered amine light stabilizer is in a range of 0.001 or more and 0.3 or less in terms of a mass ratio of the hindered amine light stabilizer to the titanium oxide (hindered amine light stabilizer / titanium oxide).

3. 3. The coating composition according to claim 1, wherein the non-tetravalent transition metal element is at least one selected from the group consisting of Cr, Mn, Fe, Co, Ni, Cu, Nb, Mo, W, and Ce.

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