JP5809795B2 - Titanium dioxide-containing composite particles - Google Patents

Description

The present invention relates to titanium dioxide-containing composite particles used for coating compositions (coating film forming compositions) and the like that require long-term weather resistance and durability.

Titanium dioxide has a high refractive index for visible light, so it is used as a white pigment for plastics, paints, inks, etc., and because it absorbs ultraviolet light, it is used as a UV shielding material for cosmetics. Widely used.

However, titanium dioxide is originally an n-type semiconductor and causes photocatalysis when irradiated with ultraviolet rays. Therefore, when blended in compositions such as cosmetics, paints, and plastics, the photocatalytic action of titanium dioxide causes discoloration, discoloration, and deterioration of organic components such as resins and oils. Therefore, for the purpose of increasing the ultraviolet resistance of titanium dioxide, by providing a coating layer of silica, alumina, cerium oxide, etc. on the surface of the titanium dioxide particles, the activation of the particle interface due to the photocatalytic ability of titanium dioxide is suppressed. Yes. In particular, cerium oxide has been attracting attention as a coating material for titanium dioxide because it has a high ultraviolet shielding effect.

For example, in Patent Document 1, a very small amount (0.01 to 1.0% by weight with respect to titanium oxide) of cerium oxide is deposited on the surface of rutile-type titanium oxide particles, and dense amorphous silica is further deposited thereon. Pigmented pigments are disclosed.

Patent Document 2 discloses a rutile-type titanium oxide particle pigment having a coating made of alumina or alumina-silica, and the particle surface is 0.5 to 2% by weight of cerium cation and stoichiometric with respect to titanium oxide. Coated titanium oxide pigments having a significant amount of sulfate or silicate anions are disclosed.

Patent Document 3 discloses composite particles having, in order from the inside, particles containing titanium oxide, a first coating layer containing cerium oxide, and a second coating layer containing silicon oxide.

Patent Document 4 discloses a composition in which titanium dioxide powder is coated with silicon dioxide together with cerium oxide.

Japanese Patent Laid-Open No. 7-315838 JP 59-184264 A International Publication No. 2008/078657 Pamphlet JP 2000-212054 A

However, when titanium dioxide having a cerium oxide coating layer as described above is used, a certain degree of photocatalytic activity suppression effect is recognized, but the weather resistance is still insufficient, and it is not possible to withstand long-term use. There were many. Actually, titanium dioxide-containing particles having satisfactory performance have not yet been obtained in a field where high and long-term weather resistance is required, such as a building outer wall surface.

On the other hand, when the coating layer is thickened for the purpose of improving the weather resistance, the ratio of titanium dioxide in the whole particle (titanium oxide purity) is relatively lowered. As a result, the original performances required for titanium oxide such as hiding power and coloring power are impaired. Therefore, it is necessary to reduce the mass of the coating layer as much as possible and keep the mass of titanium dioxide in the entire particle at a certain amount or more.

In addition, conventional titanium dioxide-containing composite particles having a coating layer of cerium oxide have insufficient affinity for organic substances such as resins when blended as pigments, and the dispersibility in the composition is not necessarily high. I can't say that. Therefore, there is also a problem that when the coating film is formed, the pigments aggregate and the transparency and gloss of the coating film are lowered.

In view of such circumstances, the present invention provides titanium dioxide-containing composite particles having good dispersibility and high and long-term weather resistance in a resin composition while maintaining the original properties of titanium dioxide. With the goal.

That is, the first aspect of the present invention, in order from the inside, is a base material containing titanium dioxide;
A first covering strip containing at least one compound selected from the group consisting of oxides of silicon, zirconium and aluminum, and hydroxides of silicon, zirconium and aluminum;
The present invention relates to a composite particle including a second coating band containing an oxide or hydroxide of cerium and an oxide or hydroxide of aluminum.

One of the preferred embodiments of the second covering band is composed of a multilayer including an inner layer containing a cerium oxide or hydroxide and an outer layer containing an aluminum oxide or hydroxide. . In another preferred embodiment, the second coating zone is a single layer containing both a cerium oxide or hydroxide and an aluminum oxide or hydroxide.

The mass of the second covering band is preferably 1 to 15 parts by mass with respect to 100 parts by mass of the titanium dioxide. Further, the second coating band may further contain at least one compound selected from the group consisting of oxides or hydroxides of zirconium, silicon, zinc, titanium, tin, phosphorus, and antimony.

Furthermore, it is preferable that the primary particle diameter of the particle | grains which match | combined the said base material particle | grain and said 1st coating band is 0.001-3 micrometers.

Moreover, the 2nd aspect of this invention is related with the coating material containing the said composite particle.

Moreover, the 3rd aspect of this invention is related with the cosmetics containing the said composite particle.

The composite particles of the present invention have weather resistance over a long period of time while maintaining the performance as a titanium oxide pigment. In addition, it has high affinity for organic substances such as resins, and is excellent in dispersibility when blended in compositions such as cosmetics, paints, and plastics. Therefore, the present invention can provide titanium dioxide-containing composite particles suitable as a pigment for a coating film-forming composition or a resin composition requiring high and long-term weather resistance.

The present invention is described in detail below. In the present specification, “titanium dioxide” and “titanium oxide” both mean the same compound represented by the chemical formula: TiO ₂ .

(Titanium dioxide-containing composite particles)
As described above, the composite particle according to the first aspect of the present invention includes, in order from the inside, a base material containing titanium dioxide, an oxide of silicon, zirconium, and aluminum, and a hydroxide of silicon, zirconium, and aluminum. A first coating zone containing at least one compound selected from the group; and a second coating zone containing an oxide or hydroxide of cerium and an oxide or hydroxide of aluminum. .

The composite particles of the present invention contain a substrate containing titanium dioxide. Since titanium dioxide has a high refractive index, it effectively scatters visible light.

Examples of the raw material for the base material containing titanium dioxide include particulate base materials such as titanium oxide particles used as pigments, composite oxides containing titanium oxide, and flaky base materials such as titanium oxide-coated mica. Among these, titanium oxide particles are preferable because of high visible light reflectance.

The proportion of titanium dioxide in the composite particles is not particularly limited, but the lower limit is preferably 50% by mass of the total mass of the composite particles, more preferably 60% by mass, and even more preferably 70% by mass, while the upper limit is Preferably, it is 90% by mass of the total mass of the composite particles, more preferably 85% by mass, and still more preferably 80% by mass. A small proportion of titanium dioxide in the composite particles means that the coating band is thick, and conversely that a large proportion of titanium dioxide means that the coating band is thin. Therefore, when the proportion of titanium dioxide in the composite particles is less than 50% by mass, the original performance (hiding power, etc.) that should be required for titanium oxide may be impaired. On the other hand, when the amount of titanium dioxide is more than 90% by mass, the coating effect may be insufficient, and the weather resistance of the composite particles may become a problem.

The composite particle of the present invention contains at least one compound selected from the group consisting of oxides of silicon, zirconium and aluminum, and hydroxides of silicon, zirconium and aluminum on the outside of the substrate containing titanium dioxide. Having a first covering strip.

The first coating band is provided as an electrical barrier between titanium oxide in the base material and cerium oxide contained in the second coating band. Since ultraviolet rays cannot be completely blocked by cerium oxide alone, when a coating layer containing cerium oxide is provided directly on the surface of titanium oxide, some ultraviolet rays may pass through the cerium oxide-containing layer and reach titanium oxide. is there. As a result, hydroxy radicals (.OH) are generated by the photocatalytic reaction of titanium oxide. Since the generated hydroxyl radical easily decomposes the cerium oxide layer, the ultraviolet blocking performance gradually deteriorates if used for a long time. This is considered to be the reason why long-term weather resistance cannot be secured in the conventional cerium oxide-coated titanium oxide. The first coating band also has a role as an electrical barrier that prevents direct action on titanium oxide even if there is ultraviolet rays that could not be shielded by cerium oxide alone.

The compound contained in the first coating band may be an oxide, a hydroxide, or a mixture of both.

Although the mass of the first covering band is not particularly limited, the lower limit is preferably 5 parts by mass with respect to 100 parts by mass of the substrate, and the upper limit is preferably 35 with respect to 100 parts by mass of the substrate. It is 25 mass parts, More preferably, it is 15 mass parts more preferably. When the first covering band is less than 5 parts by mass, the barrier effect as described above may be thinned. Conversely, when it exceeds 35 parts by mass, the original performance (hiding power) required for titanium oxide is required. Etc.) may be damaged.

The primary particle diameter of the substrate is preferably 0.001 to 3 μm. The preferable range of the primary particle diameter of the substrate varies depending on the use of the composite particles. For example, when the composite particles of the present invention are blended in a cosmetic that requires transparency, the lower limit of the primary particle diameter of the base material is preferably 0.001 μm, more preferably 0.003 μm. Preferably, it is 0.005 μm. On the other hand, the upper limit of the primary particle diameter of the base material is preferably 0.1 μm, more preferably 0.05 μm, and further preferably 0.015 μm. If the particle size is about 0.001 to 0.1 μm, visible light (about 380 nm to 780 nm) is hardly reflected, and a coating film having high transparency can be formed.

On the other hand, when the composite particles of the present invention are blended in a paint or the like, the lower limit of the primary particle diameter of the base material is preferably 0.1 μm, and more preferably 0.2 μm. On the other hand, the upper limit of the primary particle diameter of the substrate is preferably 3 μm, and more preferably 1 μm. In the case of a particle size of about 0.1 to 3 μm, it is preferable in that a high scattering ability can be exhibited.

In the specification of the present application, the primary particle diameter is a fixed direction diameter (particles) in the field of view of 100,000 times of transmission electron microscope (TEM) photograph (20,000 times for paint pigments) in the case of transparent pigments. The particle diameter (μm) defined by the distance between two parallel lines in a certain direction) was measured, and the average value was obtained by measuring the constant direction diameter of 1000 independent particles in the TEM photograph that did not overlap. Is.

The composite particles of the present invention further have a second coating band containing an oxide or hydroxide of cerium and aluminum outside the first coating band. As can be seen from the fact that cerium oxide is used for ultraviolet shielding (UV cut) glass such as sunglasses and cosmetics, it absorbs and conceals ultraviolet rays, so that the ultraviolet rays reaching titanium dioxide can be reduced.

The oxide or hydroxide of cerium and the oxide or hydroxide of aluminum may be contained in the same layer, or may be contained in separate layers constituting the second covering band, respectively. . Although not particularly limited, one of the preferred embodiments of the second covering band is an aluminum oxide layer containing a cerium oxide or hydroxide-containing layer (hereinafter also referred to as “cerium layer”) as an inner layer. Or it consists of a multilayer which has the layer (henceforth "aluminum layer") containing a hydroxide in an outer layer. Another preferred embodiment is from a single layer containing both cerium oxide or hydroxide and aluminum oxide or hydroxide (hereinafter also referred to as “cerium-aluminum single layer”). It will be.

The compound contained in the second coating band may be an oxide, a hydroxide, or a mixture of both.

The total mass of the second covering band is preferably 1 to 15 parts by mass with respect to 100 parts by mass of the titanium dioxide. The lower limit of the total mass of the second coating band is preferably 3 parts by mass, more preferably 5 parts by mass with respect to 100 parts by mass of the titanium dioxide, while the upper limit is 100 masses of the titanium dioxide. Preferably it is 12 mass parts with respect to a mass part, More preferably, it is 10 mass parts. When the total mass of the second coating band is less than 1 part by mass with respect to 100 parts by mass of titanium dioxide, the coating amount is not sufficient, and the ultraviolet shielding effect may be insufficient. On the other hand, if it exceeds 15 parts by mass, the ratio of the coating material to titanium dioxide becomes too high, and there is a risk of impairing the original performance (hiding power etc.) that should be required for titanium oxide.

The second coating band may further contain an oxide or hydroxide of at least one element selected from the group consisting of zirconium, silicon, zinc, titanium, tin, phosphorus and antimony. The oxide or hydroxide such as zirconium may be contained in any one of the cerium layer and the aluminum layer, or may be contained in a single cerium / aluminum layer. Further, it may be contained in a third layer different from the cerium layer and the aluminum layer. Preferably, the second covering band may be formed as a cerium layer, an aluminum layer, or a further outer layer of a cerium-aluminum single layer.

(Use)
The composite particles of the present invention can be suitably used in various fields such as paints, plastics, cosmetics, and automobile top coats in which conventional titanium oxide pigments and titanium oxide-containing particles have been used. Among them, those having a relatively small average primary particle size (about 0.001 to 0.1 μm) have a relatively large average primary particle size (about 0.1 to 3 μm) for cosmetics and the like that require transparency. Are suitable as pigments for automobile paints, plastics, inks, rubbers and the like. Such paints and cosmetics containing the composite particles also constitute the present invention.

Hereinafter, the present invention will be described with reference to examples. However, the following examples show some specific examples of the present invention, and the present invention is not limited thereto.
In the following examples and comparative examples, a layer made of silicon, zirconium, aluminum oxide and / or hydroxide may be referred to as a “barrier layer”.
Furthermore, a layer containing a cerium oxide or hydroxide is a “cerium layer”, a layer containing an aluminum oxide or hydroxide is an “aluminum layer”, a cerium oxide or hydroxide, and a layer of aluminum. A single layer containing both oxides or hydroxides is sometimes referred to as a “cerium-aluminum single layer”. Unless otherwise specified, “%” means “mass%”.

(Example 1)
TiO ₂ particles obtained by the sulfuric acid method were subjected to surface treatment to form a first coating band made of oxide, oxide and / or hydroxide of silicon, zirconium, aluminum on the surface of the TiO ₂ particles. Average primary particle diameter: 0.26 μm, Sakai Chemical Industry Co., Ltd.) was added to water to obtain an aqueous slurry having a TiO ₂ concentration of 400 g / L. The slurry 0.5 L was adjusted to 40 ° C. while stirring, and while maintaining this temperature, 40% cerium nitrate aqueous solution in an amount corresponding to 5 parts by mass in terms of CeO ₂ per 100 parts by mass of TiO ₂ , and Al ₂ A mixed solution with 100 g / L aluminum sulfate aqueous solution in an amount corresponding to 2 parts by mass in terms of O ₃ was added. After neutralizing the pH of the resulting slurry to 7 with an aqueous sodium hydroxide solution, it is aged over 60 minutes to form a second coating band containing cerium hydroxide and aluminum hydroxide on the TiO ₂ surface. did. The slurry after forming the coating band was washed, separated into solid and liquid, and dried at a temperature of 120 ° C. for 8 hours. Next, by pulverizing using a fluid energy mill, in order from the inside, a substrate of TiO ₂ particles, a barrier layer (first coating zone), and a cerium-aluminum single layer (second coating zone) are provided. The titanium dioxide-containing composite particles of the present invention were obtained (Sample A).

(Example 2)
TiO ₂ particles obtained by the sulfuric acid method were subjected to surface treatment to form a first coating band made of oxide, oxide and / or hydroxide of silicon, zirconium, aluminum on the surface of the TiO ₂ particles. Average primary particle size: 0.26 μm, Sakai Chemical Industry Co., Ltd.) was added to water to obtain an aqueous slurry having a TiO ₂ concentration of 400 g / L. 0.5 L of this slurry was adjusted to 40 ° C. while stirring, and while maintaining this temperature, 40% cerium nitrate aqueous solution in an amount corresponding to 5 parts by mass in terms of CeO ₂ was added per 100 parts by mass of TiO ₂ . The resulting slurry was neutralized to pH 7 with an aqueous sodium hydroxide solution and then aged for 30 minutes. Next, while maintaining this slurry at pH 7, 250 g / L sodium aluminate aqueous solution corresponding to 2 parts by mass in terms of Al ₂ O ₃ and 30% sulfuric acid were added simultaneously over 100 minutes per 100 parts by mass of TiO _2. Aging was performed for 60 minutes, and a coating layer of cerium hydroxide and aluminum hydroxide was sequentially formed on the first coating strip. The liquid containing the cerium hydroxide-coated particles was filtered. The obtained solid was washed with water, dried, and pulverized to sequentially form a base material of TiO ₂ particles, a barrier layer (first coating band), a cerium layer, and an aluminum layer (second coating band) from the inside. And cerium hydroxide-coated composite particles.

The cerium hydroxide-coated particles were fired at a temperature of 900 ° C. for 2 hours to obtain precursor particles.
Precursor particles were added to water to obtain an aqueous slurry having a TiO ₂ concentration of 400 g / L. While stirring this slurry, the temperature was raised to 80 ° C., and while maintaining this temperature, 150 g / L sodium silicate aqueous solution in an amount corresponding to 5 parts by mass in terms of SiO ₂ was added to 100 parts by mass of TiO ₂ . Next, 30% sulfuric acid was added so that the pH of the slurry was 7 over 120 minutes, and then aging was performed for 30 minutes. Next, with stirring, while maintaining the pH of the slurry at 7, with respect to 100 parts by mass of TiO ₂ , an amount of 250 g / L sodium aluminate aqueous solution corresponding to 2 parts by mass in terms of Al ₂ O ₃ and 30% sulfuric acid. Added simultaneously over 60 minutes. Thereafter, aging was performed for 60 minutes, and a coating layer of silicon hydroxide and aluminum hydroxide was formed on the aluminum layer in this order. This slurry was washed and separated into solid and liquid. The obtained solid content was dried at a temperature of 120 ° C. for 8 hours, and then pulverized using a fluid energy mill to obtain titanium dioxide-containing composite particles of the present invention (Sample B).

(Example 3)
TiO ₂ particles having an average primary particle diameter of 0.26 μm obtained by the sulfuric acid method were added to water, and wet pulverization was performed with a bead mill to obtain an aqueous slurry having a TiO ₂ concentration of 300 g / L. While stirring 0.5 L of this slurry, the temperature was raised to 80 ° C., and while maintaining this temperature, 150 g / L sodium silicate aqueous solution in an amount corresponding to 5 parts by mass in terms of SiO ₂ was added per 100 parts by mass of TiO _2. did. After adding 30% sulfuric acid so that the pH was 7 over 120 minutes, the mixture was aged for 30 minutes. Next, while maintaining the pH of the slurry at 7 under stirring, 250 g / L sodium aluminate aqueous solution and 30% sulfuric acid in an amount corresponding to 2 parts by mass in terms of Al ₂ O ₃ are added for 60 minutes per 100 parts by mass of TiO _2. At the same time, the mixture was aged for 60 minutes, and a coating layer of silicon hydroxide and aluminum hydroxide was sequentially formed on the TiO ₂ surface.
Thereafter, while maintaining this temperature, an amount of 40% cerium nitrate aqueous solution corresponding to 5 parts by mass in terms of CeO ₂ and an amount corresponding to 2 parts by mass in terms of Al ₂ O ₃ per 100 parts by mass of TiO ₂ . A mixed solution with 100 g / L aluminum sulfate aqueous solution was added. After neutralizing the pH of the resulting slurry to 7 with an aqueous sodium hydroxide solution, it is aged over 60 minutes to form a second coating band containing cerium hydroxide and aluminum hydroxide on the TiO ₂ surface. did. The slurry after forming the coating band was washed, separated into solid and liquid, and dried at a temperature of 120 ° C. for 8 hours. Next, by pulverizing using a fluid energy mill, in order from the inside, a substrate of TiO ₂ particles, a barrier layer (first coating zone), and a cerium-aluminum single layer (second coating zone) are provided. The titanium dioxide-containing composite particles of the present invention were obtained (Sample C).

(Comparative Example 1)
TiO ₂ particles having an average primary particle diameter of 0.26 μm obtained by the sulfuric acid method were added to water, and wet pulverization was performed with a bead mill to obtain an aqueous slurry having a TiO ₂ concentration of 300 g / L. While stirring 0.5 L of this slurry, the temperature was raised to 80 ° C., and while maintaining this temperature, 150 g / L sodium silicate aqueous solution in an amount corresponding to 5 parts by mass in terms of SiO ₂ was added per 100 parts by mass of TiO _2. did. After adding 30% sulfuric acid so that the pH was 7 over 120 minutes, the mixture was aged for 30 minutes. Next, while maintaining the pH of the slurry at 7 under stirring, 250 g / L sodium aluminate aqueous solution and 30% sulfuric acid in an amount corresponding to 2 parts by mass in terms of Al ₂ O ₃ are added for 60 minutes per 100 parts by mass of TiO _2. At the same time, the mixture was aged for 60 minutes, and a coating layer of silicon hydroxide and aluminum hydroxide was sequentially formed on the TiO ₂ surface. This slurry was washed and separated into solid and liquid. The obtained solid content was dried at a temperature of 120 ° C. for 8 hours, and then pulverized using a fluid energy mill to obtain a comparative titanium dioxide-containing composite particle (Sample D).

(Comparative Example 2)
TiO ₂ particles having an average primary particle size of 0.26 μm obtained by the sulfuric acid method were added to water and wet pulverized by a bead mill to obtain an aqueous slurry having a TiO ₂ concentration of 300 g / L. This slurry 0.5L was adjusted to 40 ° C. while stirring, and while maintaining this temperature, 40% cerium nitrate aqueous solution in an amount corresponding to 0.10 parts by mass in terms of CeO ₂ was added per 100 parts by mass of TiO ₂ . Thereafter, the solution was neutralized to pH 7 with an aqueous sodium hydroxide solution and then aged for 30 minutes. Next, the slurry was heated to 80 ° C. while stirring, and an aqueous 150 g / L sodium silicate solution in an amount corresponding to 5 parts by mass in terms of SiO ₂ was added per 100 parts by mass of TiO ₂ while maintaining this temperature. After adding 30% sulfuric acid so that the pH of the slurry was 7 over 120 minutes, the mixture was aged over 30 minutes. Next, with stirring, while maintaining the pH of the slurry at 7, per 100 parts by mass of TiO ₂ , 250 g / L sodium aluminate aqueous solution in an amount corresponding to 2 parts by mass in terms of Al ₂ O ₃ and 30% sulfuric acid for 60 minutes Added simultaneously. Thereafter, aging was performed for 60 minutes, and a coating layer of silicon hydroxide and aluminum hydroxide was sequentially formed on the CeO ₂ layer. This slurry was washed and separated into solid and liquid. The obtained solid content was dried at a temperature of 120 ° C. for 8 hours, and then pulverized using a fluid energy mill to obtain a comparative titanium dioxide-containing composite particle (Sample E).

(Comparative Example 3)
TiO ₂ particles having an average primary particle size of 0.20 μm were added to water, and wet pulverization was performed with a bead mill to obtain an aqueous slurry having a TiO ₂ concentration of 300 g / L. While stirring 0.5 L of this slurry, the temperature was raised to 70 ° C., and while maintaining this temperature, a 250 g / L sodium aluminate aqueous solution in an amount corresponding to 2 parts by mass in terms of Al ₂ O ₃ per 100 parts by mass of TiO _2. Was added. After stirring for 30 minutes, the pH of the slurry was neutralized to 7 with 30% sulfuric acid and aged for 60 minutes to form an aluminum hydroxide coating layer on the TiO ₂ surface. This slurry was washed and separated into solid and liquid. The obtained solid was dried at a temperature of 120 ° C. for 8 hours and then pulverized using a fluid energy mill to obtain a titanium oxide surface-treated pigment having an aluminum hydroxide coating layer.

This titanium oxide surface-treated pigment was added to water to obtain an aqueous slurry having a TiO ₂ concentration of 400 g / L. 0.5 L of this slurry was adjusted to 40 ° C. with stirring. While maintaining this temperature, 40% cerium nitrate aqueous solution in an amount corresponding to 10 parts by mass in terms of CeO ₂ was added per 100 parts by mass of TiO ₂ . After neutralizing to pH 7-9 with an aqueous sodium hydroxide solution, the mixture was aged for 30 minutes. The liquid containing cerium hydroxide-coated particles was filtered. The obtained solid content was washed with water, dried and pulverized to obtain particles having a coating layer of cerium hydroxide.

The cerium hydroxide-coated particles were added to water to obtain an aqueous slurry having a TiO ₂ concentration of 400 g / L. While stirring this 0.5 L of slurry, the temperature was adjusted to 80 ° C., and while maintaining this temperature, 150 g / L No. 3 sodium silicate in an amount corresponding to 28.5 parts by mass in terms of SiO ₂ per 100 parts by mass of TiO ₂ An aqueous solution was added. At this time, 2N dilute sulfuric acid was also added to adjust the pH of the solution to 6 to 8, and a coating layer was formed on the cerium hydroxide-coated particles. This liquid was filtered, and the obtained solid content was washed with water, dried and pulverized to obtain precursor particles. The precursor particles were calcined at a temperature of 500 ° C. for 2 hours and pulverized using a fluid energy mill to obtain titanium dioxide-containing composite particles for comparison (sample F).

(Comparative Example 4)
TiO ₂ particles obtained by the sulfuric acid method were subjected to surface treatment to form a first coating band made of oxide, oxide and / or hydroxide of silicon, zirconium, aluminum on the surface of the TiO ₂ particles. Average primary particle size: 0.26 μm, Sakai Chemical Industry Co., Ltd.) was added to water to obtain an aqueous slurry having a TiO ₂ concentration of 400 g / L. 0.5 L of this slurry was adjusted to 40 ° C. while stirring, and while maintaining this temperature, 40% cerium nitrate aqueous solution in an amount corresponding to 20 parts by mass in terms of CeO ₂ was added per 100 parts by mass of TiO ₂ . After neutralizing to pH 7 with an aqueous sodium hydroxide solution, the mixture was aged for 30 minutes to form a cerium hydroxide coating layer on the TiO ₂ surface. This slurry was washed and separated into solid and liquid. The obtained solid content was dried at a temperature of 120 ° C. for 8 hours, and then pulverized using a fluid energy mill to obtain comparative titanium dioxide-containing composite particles (Sample G).

(Comparative Example 5)
TiO ₂ particles having an average primary particle diameter of 0.26 μm obtained by the sulfuric acid method were added to water, and wet pulverization was performed with a bead mill to obtain an aqueous slurry having a TiO ₂ concentration of 300 g / L. 0.5 L of this slurry was adjusted to 40 ° C. while stirring, and while maintaining this temperature, 40% cerium nitrate aqueous solution in an amount corresponding to 5 parts by mass in terms of CeO ₂ was added per 100 parts by mass of TiO ₂ . After neutralizing to pH 7 with an aqueous sodium hydroxide solution, the mixture was aged for 30 minutes to form a cerium hydroxide coating layer on the TiO ₂ surface. This slurry was washed, solid-liquid separated, dried at a temperature of 120 ° C. for 8 hours, and then pulverized using a fluid energy mill to obtain a comparative titanium dioxide-containing composite particle (Sample H).

(Comparative Example 6)
Titanium dioxide-containing composite in the same procedure as in Example 1 except that a coating layer of aluminum hydroxide is not provided and the coating amount of cerium hydroxide is 0.5 parts by mass in terms of CeO ₂ per 100 parts by mass of TiO ₂ Particles were obtained (Sample I).

(Comparative Example 7)
D-918 (average primary particles) in which TiO ₂ particles obtained by the sulfuric acid method were surface-treated to form a coating band composed of oxides and / or hydroxides of silicon, zirconium, aluminum on the surface of the TiO ₂ particles. Diameter: 0.26 μm, Sakai Chemical Industry Co., Ltd.) was added to water to obtain an aqueous slurry having a TiO ₂ concentration of 400 g / L. 0.5 L of this slurry was adjusted to 40 ° C. while stirring, and while maintaining this temperature, 40% cerium nitrate aqueous solution in an amount corresponding to 5 parts by mass in terms of CeO ₂ was added per 100 parts by mass of TiO ₂ . After neutralizing to pH 7 with an aqueous sodium hydroxide solution, the mixture was aged for 30 minutes. The slurry was heated to 80 ° C. while stirring, and while maintaining this temperature, 150 g / L sodium silicate aqueous solution in an amount corresponding to 5 parts by mass in terms of SiO ₂ was added per 100 parts by mass of TiO ₂ . After adding 30% sulfuric acid so that the pH was 7 over 120 minutes, aging was performed over 30 minutes, and a coating layer of cerium hydroxide and silicon hydroxide was sequentially formed on the TiO ₂ surface. This slurry was washed, solid-liquid separated, dried at a temperature of 120 ° C. for 8 hours, and then pulverized using a fluid energy mill to obtain the titanium dioxide-containing composite particles of the present invention (Sample J).

Evaluation 1: Evaluation of weather resistance Using the samples obtained in the Examples and Comparative Examples, the resin component (alkyd resin + butylated melamine resin) mass / titanium dioxide pigment mass = 1/1 according to the formulation shown in Table 1. A coating composition was obtained. Next, the obtained coating composition was applied onto a bonderite-treated steel plate using a bar coater # 50, and baked at 140 ° C. for 30 minutes to prepare a test piece. This test piece was exposed to light by spraying pure water at regular intervals while irradiating light with a sunshine weather meter.
The 60 degree gloss value is measured using a gloss meter (GM-26D: manufactured by Murakami Color Research Laboratory) at regular intervals, and the time required for the 60 degree gloss value to be 50% or less of the initial 60 degree gloss value is determined. Compared. The longer this time, the better the weather resistance.

Evaluation 2: Evaluation of concealment The coating composition obtained in Evaluation 1 was applied on a glass plate using a 1.5 mil applicator and baked at 140 ° C. for 30 minutes to form a coating film. White paper and black paper were applied to the opposite glass surface formed into a coating film, and the coating film was measured for each Y using a color meter (SE-2000: manufactured by Nippon Denshoku Industries Co., Ltd.). At this time, the measured value of the white paper is Yw, and the measured value of the black paper is Yb.
The concealability was calculated and compared by contrast ratio (CR) = Yb / Yw × 100.
The greater this value, the better the concealment.

Evaluation 3: Evaluation of Gloss The coating composition obtained in Evaluation 1 was applied on a glass plate using a 1.5 mil applicator, baked at 140 ° C. for 30 minutes, and then formed into a coating film. The gloss value of the 20 ° -20 ° mirror surface of the coating film surface was measured with a gloss meter (GM-26D: manufactured by Murakami Color Research Laboratory). The larger this value, the better the gloss and the better the pigment dispersion in the coating film.

(Preparation Example 1)
-Preparation of cosmetic composition A cosmetic composition was prepared based on the composition shown in Table 3. First, each component shown as composition A was stirred for 15 minutes at 15000 rpm using a homogenizer to prepare liquid A. Next, each component shown as the composition B was mixed to prepare a liquid B. Finally, liquid A and liquid B were combined and mixed for 15 minutes with a paint shaker to prepare a cosmetic composition.

(Preparation Example 2)
-Preparation of transparency coating composition Each component shown in the following Table 4 was mixed for 90 minutes with a paint conditioner (manufactured by Red Devil) to prepare a coating composition having transparency.

Claims (9)

In order from the inside, a base material containing titanium dioxide,
Contains at least silicon oxide and / or hydroxide and zirconium oxide and / or hydroxide, or at least silicon oxide and / or hydroxide and aluminum oxide and / or hydroxide Or a first covering band containing at least zirconium oxide and / or hydroxide and aluminum oxide and / or hydroxide ,
A composite particle comprising a second coating band containing an oxide or hydroxide of cerium and an oxide or hydroxide of aluminum. 2. The composite particle according to claim 1, wherein the second covering band is composed of a multilayer including a layer containing a cerium oxide or hydroxide and a layer containing an aluminum oxide or hydroxide. 3. The composite particle according to claim 2 , wherein the second covering band is composed of a multilayer including an inner layer containing a cerium oxide or hydroxide and an outer layer containing an aluminum oxide or hydroxide. 2. The composite particle according to claim 1, wherein the second covering band is composed of a single layer containing both a cerium oxide or hydroxide and an aluminum oxide or hydroxide. 5. The composite particle according to claim 1, wherein a total mass of the second coating band is 1 to 15 parts by mass with respect to 100 parts by mass of the titanium dioxide. The second coating band further comprises at least one compound selected from the group consisting of oxides or hydroxides of zirconium, silicon, aluminum, zinc, titanium, tin, phosphorus, and antimony. The composite particle according to any one of claims. The composite particle according to any one of claims 1 to 6, wherein a particle diameter of the substrate is 0.001 to 3 µm. The coating material containing the composite particle as described in any one of Claims 1-7. Cosmetics containing the composite particles according to any one of claims 1 to 7.