JP2022156972A - Surface-coated titanium oxide powder, dispersion, and cosmetics - Google Patents

Abstract

To provide a surface-coated titanium oxide powder with sufficiently suppressed photocatalytic activity of titanium oxide powder, and to provide a dispersion and cosmetics containing the same.SOLUTION: A surface-coated titanium oxide powder according to the present invention is a titanium oxide powder whose surface is coated with an inorganic material. The pore volume (mL/cm3) per 1 cm3 of the inorganic material is 6.0 or less when the pore volume with a pore size of 100 nm or less is measured.SELECTED DRAWING: None

Description

TECHNICAL FIELD The present invention relates to surface-coated titanium oxide powder, and dispersions and cosmetics containing the same.

Titanium oxide particles are excellent in light reflection properties, ultraviolet shielding properties, and hiding power. Therefore, submicron-sized to micron-sized titanium oxide particles are used in cosmetics such as foundations.
As titanium oxide particles with high light scattering performance for use in cosmetics, anatase-type polyhedral titanium oxide particles have been proposed (see, for example, Patent Documents 1 and 2).

However, titanium oxide particles have photocatalytic activity. Therefore, the titanium oxide particles degrade the oils contained in the cosmetics. Therefore, in order to suppress the photocatalytic activity of titanium oxide particles, surface-coated titanium oxide particles have been proposed in which the surfaces of titanium oxide particles are coated with silicon oxide and an inorganic compound (see, for example, Patent Document 3).

JP 2006-076798 A JP 2021-011396 A Japanese Patent Publication No. 2017-528563

However, there has been a demand for a surface-coated titanium oxide powder capable of further suppressing photocatalytic activity.

The present invention has been made in view of the above circumstances, and aims to provide a surface-coated titanium oxide powder in which the photocatalytic activity of the titanium oxide powder is sufficiently suppressed, as well as dispersions and cosmetics containing the same. aim.

In order to solve the above problems, one aspect of the present invention provides a titanium oxide powder whose surface is coated with an inorganic material,
Provided is a surface-coated titanium oxide powder having a pore volume (mL/cm ³ ) per 1 cm ³ of the inorganic material of 6.0 or less when the pore volume with a pore diameter of 100 nm or less is measured.

In one aspect of the present invention, the inorganic material may contain at least a silicon compound and an aluminum compound.

In one aspect of the present invention, the crystal phase of the titanium oxide powder may be an anatase type.

In one aspect of the present invention, the inorganic material may be 5% by volume or more and 20% by volume or less with respect to the total volume of the titanium oxide and the inorganic material.

In order to solve the above problems, one aspect of the present invention provides a dispersion containing the surface-coated titanium oxide powder and a dispersion medium.

In order to solve the above problems, one aspect of the present invention provides a cosmetic containing the surface-coated titanium oxide powder and a cosmetic base.

According to the present invention, it is possible to provide a surface-coated titanium oxide powder in which the photocatalytic activity of the titanium oxide powder is sufficiently suppressed, as well as dispersions and cosmetics containing the same.

Embodiments of the surface-coated titanium oxide powder of the present invention, and dispersions and cosmetics containing the same will be described.
It should be noted that the present embodiment is specifically described for better understanding of the gist of the invention, and does not limit the invention unless otherwise specified.

[Surface-coated titanium oxide powder]
The surface-coated titanium oxide powder of this embodiment is titanium oxide powder whose surface is coated with an inorganic material. That is, the surface-coated titanium oxide powder of this embodiment includes titanium oxide powder and an inorganic material that coats the surface of the titanium oxide powder. In addition, the surface-coated titanium oxide powder of the present embodiment has a pore volume (mL/cm ³ ) of 6.0 per 1 cm ³ of the inorganic material when the pore volume with a pore diameter of 100 nm or less is measured. It is below.
In addition, "an inorganic material coats the surface of the titanium oxide powder" means that the inorganic material adheres to the surface of the titanium oxide particles constituting the titanium oxide powder.

(Method for measuring pore volume (mL/cm ³ ) per 1 cm ³ of inorganic material)
In the surface-coated titanium oxide powder of the present embodiment, the pore volume (mL/cm ³ ) per 1 cm ³ of the inorganic material is the same as the pore volume with a pore diameter of 100 nm or less and the pore volume of the surface-coated titanium oxide powder. It can be calculated by measuring the mass of titanium oxide and the inorganic material.

(Content of titanium oxide and inorganic material)
The contents of Ti and the elements constituting the inorganic material in the surface-coated titanium oxide powder can be measured with an ICP emission spectrometer (ICP-AES). By appropriately converting the content of the obtained element using the molecular weight of the compound, the mass % of titanium oxide and inorganic material in the surface-coated titanium oxide powder can be calculated.
By converting the obtained mass % into volume using the true density, the volume % of titanium oxide and the inorganic material can be calculated.
The mass fraction of the inorganic material can be calculated by dividing the calculated mass % of the inorganic material by the mass % of the surface-coated titanium oxide powder (titanium oxide and inorganic material).
Further, the volume fraction of the inorganic material can be calculated by dividing the calculated volume % of the inorganic material by the volume % of the surface-coated titanium oxide powder (titanium oxide and inorganic material).
The density (g/cm ³ ) of the inorganic material can also be calculated by dividing the mass % of the inorganic material by the volume % of the inorganic material.

The pore volume (mL / g) with a pore diameter of 100 nm or less is measured by an adsorption isotherm with a specific surface area measuring device (trade name: Belsorp-miniII, manufactured by Microtrac Benole), and the BJH method is used to measure a pore diameter of 100 nm. It is obtained by measuring the following pore volume A.

The obtained pore volume A (mL/g) is the pore volume per 1 g of the surface-coated titanium oxide powder. Therefore, by dividing the pore volume A by the mass fraction of the inorganic material calculated above, the pore volume B (mL/g) per 1 g of the inorganic material can be calculated.
Next, by multiplying the pore volume B (mL/g) by the density of the inorganic material obtained above, the pore volume C (mL/cm ³ ) per 1 cm ³ of the inorganic material can be calculated.

The reason for measuring the pore volume of 100 nm or less is to measure the denseness of the film formed by the inorganic material that coats the surface of the titanium oxide particles. That is, pores of 100 nm or less are generated in the film covering the surface of the titanium oxide particles. On the other hand, pores larger than 100 nm are presumed to be gaps between surface-coated titanium oxide particles. Therefore, whether or not the inorganic material is densely coated can be confirmed by measuring the pore volume of 100 nm or less.
By calculating the pore volume C (mL/cm ³ ) per 1 cm ³ of the inorganic material, it is possible to measure the denseness of the film on the surface of the titanium oxide particles made of the inorganic material.
That is, the smaller the pore volume C (mL/cm ³ ), the denser the film formed of the inorganic material, so that the photocatalytic activity of the titanium oxide particles can be suppressed.

In the surface-coated titanium oxide powder of the present embodiment, the pore volume (mL/cm ³ ) per 1 cm ³ of the inorganic material is 6.0 or less, preferably 5.5 or less, more preferably 5.0 or less. is more preferable. The lower limit of the above value may be 0.5 or more, 1.0 or more, or 1.5 or more. If the pore volume exceeds 6.0, the fine surface coating is not applied to the titanium oxide powder, and the suppression of photocatalytic activity becomes insufficient, which is not preferable.

The inorganic material is preferably 5% by volume or more and 20% by volume or less, more preferably 5% by volume or more and 15% by volume or less, and 5% by volume or more of the total volume of titanium oxide and the inorganic material. It is more preferably 10% by volume or less. If it is less than 5% by volume, the photocatalytic activity of titanium oxide is not sufficiently suppressed, which is not preferable. On the other hand, if the content of the inorganic material exceeds 20% by volume, the amount of the inorganic material present in the surface-coated titanium oxide powder increases. Therefore, in order to obtain the desired scattering properties, it is necessary to increase the amount of the surface-coated titanium oxide powder blended into the cosmetic, which is not preferable because it reduces the degree of freedom in formulating.

The inorganic material is preferably 1% by mass or more and 15% by mass or less, more preferably 2% by mass or more and 10% by mass or less, and 3% by mass or more of the total mass of titanium oxide and the inorganic material. It is more preferably 8% by mass or less. If it is less than 1% by mass, the suppression of the photocatalytic activity of titanium oxide becomes insufficient, which is not preferable. On the other hand, if the content of the inorganic material exceeds 15% by mass, the amount of the inorganic material present in the surface-coated titanium oxide powder increases. Therefore, in order to obtain the desired scattering properties, it is necessary to increase the amount of the surface-coated titanium oxide powder blended into the cosmetic, which is not preferable because it reduces the degree of freedom in formulating.

The specific surface area of the surface-coated titanium oxide powder of the present embodiment is preferably 5 m ² /g or more and 15 m ² /g or less, more preferably 5 m ² /g or more and 13 m ² /g or less.
When the BET specific surface area of the surface-coated titanium oxide powder is 5 m ² /g or more and 15 m ² /g or less, the bluishness peculiar to titanium oxide particles can be further reduced while maintaining hiding power and transparency. is advantageous. Further, when the BET specific surface area of the surface-coated titanium oxide powder is 5 m ² /g or more, light scattering is suppressed and transparency is improved. On the other hand, when the BET specific surface area of the surface-coated titanium oxide powder is 15 m ² /g or less, the light scattering intensity of short wavelengths is reduced compared to the light scattering intensity of long wavelengths, and the bluishness is reduced.

As a method for measuring the BET specific surface area, for example, a method of measuring from a nitrogen adsorption isotherm by the BET multipoint method using a fully automatic specific surface area measuring device (trade name: BELSORP-MiniII, manufactured by Microtrack Bell) can be mentioned. be done.

(particle size distribution)
The value (d10) when the cumulative volume percentage of the volume particle size distribution of the primary particle diameter of the surface-coated titanium oxide powder of the present embodiment is 10% is divided by the value (d50) when the cumulative volume percentage is 50%. The value (d10/d50) (hereinafter sometimes abbreviated as “d10/d50”) is preferably 0.3 or more and 1 or less. The lower limit of d10/d50 may be 0.4 or more, or 0.5 or more. The upper limit of d10/d50 may be 0.9 or less, 0.8 or less, or 0.7 or less.
When d10/d50 is within the above range, a cosmetic with better hiding power can be obtained when blended in the cosmetic.

d10 and d50 are obtained by the following procedure. The primary particle size of 50 surface-coated titanium oxide powders is measured. The measured primary particle diameter is cubed and multiplied by a constant to obtain the volume. The constant may be appropriately determined according to the shape of the surface-coated titanium oxide powder. By way of example, the constant for polyhedral shapes with eight or more faces is 0.145, and the constant for spherical shapes is 4.19 (4π/3). Using the measured primary particle size and the calculated volume value, the volume particle size distribution of the primary particle size is calculated. d10 means the primary particle diameter at 10% accumulation, and d50 means the primary particle diameter at 50% accumulation.

Here, the primary particle size of the surface-coated titanium oxide powder means the longest linear portion (maximum length) of the surface-coated titanium oxide powder. For example, the primary particle size of spherical surface-coated titanium oxide powder means the diameter. For example, the primary particle diameter of a rod-shaped surface-coated titanium oxide powder means the longest linear portion in the longitudinal direction. For example, the primary particle diameter of the octahedral surface-coated titanium oxide powder means the maximum value of a line segment connecting two facing vertices (hereinafter sometimes referred to as "distance between vertexes"). Note that the two vertices facing each other are not adjacent vertices. That is, the line segment connecting the two vertices is a line segment that does not pass through the surface of the particle but passes through the inside of the particle. The combination of vertices furthest from each other gives the maximum value.

The primary particle size of the surface-coated titanium oxide powder is obtained by the following method. When the surface-coated titanium oxide powder of the present embodiment is observed using a scanning electron microscope (SEM), a predetermined number of surface-coated titanium oxide powders, such as 200, 100, or 50, are selected. . Then, it can be obtained by measuring the longest linear portion (maximum length) of each of these surface-coated titanium oxide powders.
In addition, when the surface-coated titanium oxide particles are aggregated, the aggregate particle size of the aggregate is not measured. The surface-coated titanium oxide particles (primary particles) constituting this aggregate are measured and taken as the primary particle size.
When the shape of the surface-coated titanium oxide particles is damaged and the shape before damage can be estimated, the primary particle size is measured based on the shape of the particles before damage.

In order to adjust the BET specific surface area to the above-mentioned BET specific surface area, the d50 of the surface-coated titanium oxide powder of the present embodiment is preferably 100 nm or more and 1000 nm or less, more preferably 150 nm or more and 800 nm or less, and 200 nm or more and 700 nm. or less, and most preferably 250 nm or more and 600 nm or less. Note that d50 corresponds to the average primary particle diameter of the surface-coated titanium oxide powder of this embodiment.

The content of titanium oxide in the surface-coated titanium oxide powder of the present embodiment is preferably 85% by mass or more and 99% by mass or less, more preferably 90% by mass or more and 98% by mass or less. A desired light scattering effect can be obtained when the content of titanium oxide is 85% by mass or more. On the other hand, when the content of titanium oxide is 99% by mass or less, the photocatalytic activity can be suppressed.

As a method for confirming whether or not the photocatalytic activity is suppressed, there is a method of measuring the color difference ΔE before and after irradiation with simulated sunlight.
Specifically, it can be confirmed whether the photocatalytic activity is suppressed by the following measuring method.

A mixture is prepared by mixing 3 g of the surface-coated titanium oxide powder and 4 g of 1,3-butanediol. The obtained mixture was sandwiched in an assembled quartz cell for a spectrophotometer (model: AB20/UV-0.5, manufactured by GL Sciences), and the chromaticity (L ^* , a ^* , b ^* ) was measured in the ultraviolet visible near infrared range. It is measured with a spectrophotometer (manufactured by JASCO Corporation, model number: V-770) using an integrating sphere.
Next, the assembled quartz cell containing the above mixture is irradiated with simulated sunlight with an integrated light intensity of 5000 kJ/m ² from a xenon lamp (EYE SUN-CUBE Xenon compact light irradiation test device manufactured by Iwasaki Electric Co., Ltd.).
The assembled quartz cell after irradiation is set again in the spectrophotometer, and the chromaticities (L ^* , a ^* , b ^* ) are measured.
Next, a color difference ΔE, which is a change in chromaticity (L ^* , a ^* , b ^* ) before and after irradiation with simulated sunlight, is calculated by the following general formula (1).
Color difference ΔE=((ΔL ^* ) ² +(Δa ^* ) ² +(Δb ^* ) ² ) ^1/2 (1)

The surface-coated titanium oxide powder whose photocatalytic activity is suppressed has a small ΔE. Therefore, the color difference ΔE of the surface-coated titanium oxide powder of this embodiment is preferably 5.0 or less, more preferably 4.5 or less. The lower limit of the color difference ΔE is preferably 0, but may be 0.5 or 1.0.

The secondary particle size of the surface-coated titanium oxide powder of the present embodiment is preferably 1 μm or more and 10 μm or less, more preferably 1 μm or more and 9 μm or less, and even more preferably 1 μm or more and 8 μm or less.
When the average particle size of the secondary particles is 1 μm or more and 10 μm or less, it is preferable in terms of suppressing the rough feel when applied to the skin and providing an excellent feel.
When the average particle size of the secondary particles is less than 1 μm, the average primary particle size becomes too small, making it impossible to obtain hiding power and transparency, which is not preferable. On the other hand, if the average particle diameter of the secondary particles exceeds 10 μm, it is not preferable because it gives a rough feeling when applied to the skin, and the feel is poor.
The feel in the present embodiment is, for example, the feel of touching the skin coated with the cosmetic containing the titanium oxide powder with fingers when the cosmetic is applied to the skin.

The "average secondary particle size" of the surface-coated titanium oxide powder of the present embodiment is a numerical value obtained by the following method. That is, the surface-coated titanium oxide powder of this embodiment is subjected to dry measurement using a particle size distribution analyzer MASTERSIZER3000 (manufactured by Malvern). The particle diameter (d50) when the cumulative volume percentage of the obtained particle size distribution is 50% is the average secondary particle diameter of the present embodiment.

(Titanium oxide powder)
The titanium oxide powder contained in the surface-coated titanium oxide powder of this embodiment is an aggregate of titanium oxide particles. Titanium oxide particles are not particularly limited as long as they are used in cosmetics.
Note that the titanium oxide particles of the present embodiment do not include titanium oxide particles doped with a different element.

The crystal phase of the titanium oxide powder of the present embodiment is preferably an anatase type. A cosmetic containing an anatase-type titanium oxide powder has a higher hiding power when applied to the skin, and a color close to the color of human skin can be obtained when mixed with a cosmetic base. Advantageous.

Whether the surface-coated titanium oxide powder is of the anatase type can be confirmed by, for example, an X-ray diffractometer (trade name: X'Pert PRO, manufactured by Spectris). If the result of measurement by the X-ray diffractometer is an anatase single phase, the surface-coated titanium oxide powder is an anatase type.

The titanium oxide powder of the present embodiment is preferably an aggregate of single-crystal titanium oxide particles.
When the surface-coated titanium oxide powder of the present embodiment is composed of single-crystal titanium oxide particles, the refractive index of the surface-coated titanium oxide powder is improved, resulting in excellent light scattering properties. Therefore, when blended in cosmetics, it is possible to improve the hiding power and suppress the phenomenon that the appearance of color differs depending on the viewing angle of the skin.
Here, the crystallinity of the titanium oxide powder, that is, whether or not the titanium oxide particles are single crystals can be confirmed by the following method.

(Crystallinity (method for distinguishing between single crystal and polycrystal))
Whether the titanium oxide particles are single crystals or polycrystals can be confirmed by observing the crystal axes of the particles using a field emission transmission electron microscope (FE-TEM). A crystal in which the direction of the crystal axis does not change regardless of the position of the crystal is a single crystal, and a crystal in which the direction of the crystal axis changes depending on the position of the crystal is a polycrystal.

(BET specific surface area)
The BET specific surface area of the titanium oxide powder of the present embodiment is preferably 5 m ² /g or more and 15 m ² /g or less, more preferably 5 m ² /g or more and 13 m ² /g or less.
When the BET specific surface area of the titanium oxide powder is 5 m ² /g or more and 15 m ² /g or less, it is advantageous in that the paleness peculiar to titanium oxide particles can be further reduced while maintaining hiding power and transparency. is. Further, when the BET specific surface area of the surface-coated titanium oxide powder is 5 m ² /g or more, light scattering is suppressed and transparency is improved. On the other hand, when the BET specific surface area of the surface-coated titanium oxide powder is 15 m ² /g or less, the light scattering intensity of short wavelengths is reduced compared to the light scattering intensity of long wavelengths, and the bluishness is reduced.

As a method for measuring the BET specific surface area, for example, a method of measuring from a nitrogen adsorption isotherm by the BET multipoint method using a fully automatic specific surface area measuring device (trade name: BELSORP-MiniII, manufactured by Microtrack Bell) can be mentioned. be done.

(particle size distribution)
The value (d10/d50) obtained by dividing the value (d10) when the cumulative volume percentage of the volume particle size distribution of the primary particle diameter of the titanium oxide particles is 10% by the value (d50) when the cumulative volume percentage is 50%. (hereinafter sometimes abbreviated as "d10/d50") is preferably 0.3 or more and 1 or less. The lower limit of d10/d50 may be 0.4 or more, or 0.5 or more. The upper limit of d10/d50 may be 0.9 or less, 0.8 or less, 0.7 or less, or 0.6 or less.
When d10/d50 is within the above range, a cosmetic with better hiding power can be obtained when blended in the cosmetic.

d10 and d50 are obtained by the following procedure. The primary particle size of 50 titanium oxide particles is measured. The measured primary particle diameter is cubed and multiplied by a constant to obtain the volume. The constant may be appropriately determined according to the shape of the titanium oxide particles. By way of example, the constant for polyhedral shapes with eight or more faces is 0.145, and the constant for spherical shapes is 4.19 (4π/3). Using the measured primary particle size and the calculated volume value, the volume particle size distribution of the primary particle size is calculated. d10 means the primary particle diameter at 10% accumulation, and d50 means the primary particle diameter at 50% accumulation.

Here, the primary particle size of the titanium oxide particles means the longest linear portion (maximum length) of the titanium oxide particles. For example, the primary particle size of spherical titanium oxide particles means the diameter. For example, the primary particle size of rod-shaped titanium oxide particles means the longest linear portion in the longitudinal direction. For example, the primary particle size of octahedral titanium oxide particles means the maximum value of a line segment connecting two facing vertices (hereinafter sometimes referred to as "distance between vertices"). Note that the two vertices facing each other are not adjacent vertices. That is, the line segment connecting the two vertices is a line segment that does not pass through the surface of the particle but passes through the inside of the particle. The combination of vertices furthest from each other gives the maximum value.

The primary particle size of titanium oxide particles is obtained by the following method. When the surface-coated titanium oxide powder of this embodiment is observed using a scanning electron microscope (SEM), a predetermined number of titanium oxide particles, for example 200, 100, or 50, are selected. Then, it can be obtained by measuring the longest linear portion (maximum major diameter) of each of these titanium oxide particles.
In addition, when the titanium oxide particles are agglomerated, the agglomerated particle diameter of the agglomerate is not measured. The titanium oxide particles (primary particles) constituting this aggregate are measured and taken as the primary particle diameter.
Further, when the shape of the titanium oxide particles is damaged and the shape before damage can be estimated, the primary particle size is measured based on the shape of the particles before damage.

(crystallinity)
The titanium oxide powder of the present embodiment preferably has a crystallinity of 0.95 or more, more preferably 0.96 or more, even more preferably 0.97 or more, and 0.98 or more. is most preferred. The upper limit of the crystallinity of the titanium oxide powder of this embodiment is 1.0.
When the degree of crystallinity is 0.95 or more, the refractive index of the titanium oxide particles increases, the light scattering intensity increases, and light can be scattered with a small addition amount. This suppresses the phenomenon in which colors appear differently depending on the viewing angle.

The crystallinity of titanium oxide powder can be measured by X-ray diffraction (XRD). Specifically, first, an X-ray diffractometer (trade name: X'Pert PRO MPS, manufactured by PANalytical) was used, CuKα rays were used as the X-ray source, the output was 45 kV, 40 mA, and the diffraction angle 2θ was 20°. Measure the X-ray intensity in the range of 30° from . The obtained X-ray diffraction pattern is subjected to profile fitting of the crystalline portion (peak) and the amorphous portion (halo) to calculate the integrated intensity of each. The crystallinity is defined as the ratio of the integrated intensity of the crystalline portion to the total integrated intensity.

The shape of the titanium oxide particles in the surface-coated titanium oxide powder of the present embodiment preferably includes a polyhedral shape having eight or more faces.
Since the shape of the titanium oxide particles has eight or more faces, it is possible to scatter light over a wide range. Therefore, when the cosmetic containing the surface-coated titanium oxide powder is applied to the skin, it is possible to suppress the phenomenon that the appearance of the color differs depending on the viewing angle of the skin.

The content of polyhedral titanium oxide particles having eight or more faces in the surface-coated titanium oxide powder of the present embodiment is represented by number % calculated by the method described later. That is, the content of the polyhedral titanium oxide particles having eight or more faces in the surface-coated titanium oxide powder is preferably 50% by number or more, may be 60% by number or more, and may be 70% by number. or more. The upper limit of the content of polyhedral titanium oxide particles having eight or more faces in the surface-coated titanium oxide powder may be 70% by number, 80% by number, or 90% by number. may be 100% by number.
When the content of polyhedral titanium oxide particles having eight or more faces in the surface-coated titanium oxide powder is 50% by number or more, when a cosmetic containing the surface-coated titanium oxide powder is applied to the skin, This suppresses the phenomenon that the appearance of colors differs depending on the viewing angle of the skin. In addition, it is preferable in that it is possible to further reduce the bluish whiteness peculiar to titanium oxide particles while maintaining excellent hiding power and transparency.

The content of the polyhedral titanium oxide particles having eight or more faces in the surface-coated titanium oxide powder of the present embodiment, i.e., the number percent, is determined by, for example, scanning electron microscope (SEM) analysis of the surface It is a value calculated by observing 50 titanium oxide particles contained in the coated titanium oxide powder and counting the number of polyhedral titanium oxide particles having eight or more faces contained in the 50 particles.

Any polyhedral shape with eight or more faces can be chosen. A particle having a polyhedral shape is a particle having a plurality of faces. Examples of polyhedral shapes include octahedral, decahedral, dodecahedral, icosahedral, and star shapes. Each face of the polyhedral shape may be substantially all of the same shape, or may include a plurality of faces of different shapes, such as two.
The polyhedral shape may be a regular polyhedral shape, or may be another polyhedral shape. Specific examples of the polyhedral shape include shapes such as a regular octahedron and a double quadrangular pyramid. Among these, the octahedral shape is preferable because it can scatter light over a wide range.
The polyhedral shape includes a polyhedron whose corners are rounded and wholly or partially rounded.
The polyhedral shape also includes shapes in which polyhedral particles are partially broken. That is, if a particle has a shape similar to a polyhedral particle and it is assumed that this shape was formed from the polyhedral particle by breakage, it is regarded as a polyhedral particle.
Aggregated particles in which polyhedral particles are aggregated together are also included.

(inorganic material)
The surface-coated titanium oxide powder of this embodiment has an inorganic material on its surface.
The inorganic material is not particularly limited as long as it can suppress the photocatalytic activity of the titanium oxide powder. The inorganic material may be an oxide or a hydroxide. The inorganic material may be at least one oxide selected from the group consisting of zinc, titanium, cerium, iron, magnesium, calcium, silicon and aluminum, or may be a hydroxide. The inorganic material may be a hydrate.
The inorganic material preferably contains a silicon compound and an aluminum compound in that the photocatalytic activity is likely to be suppressed.
Silicon compounds include, for example, silica and hydrated silica.
Examples of aluminum compounds include aluminum hydroxide, alumina, and alumina hydrate.

The surface-coated titanium oxide powder of this embodiment may have an organic material on the surface in addition to the inorganic material. The surface-coated titanium oxide powder of the present embodiment is preferable because it has an organic material on its surface in addition to an inorganic material, so that it can be more easily blended into cosmetics.

Examples of organic materials include silicone compounds, organopolysiloxanes, fatty acids, fatty acid soaps, fatty acid esters, organic titanate compounds, surfactants, and non-silicone compounds. These organic materials may be used individually by 1 type, and may use 2 or more types together.

Examples of silicone compounds include silicone oils, alkylsilanes, fluoroalkylsilanes, methicone, hydrogen dimethicone, triethoxysilylethylpolydimethylsiloxyethyl dimethicone, triethoxysilylethylpolydimethylsiloxyethylhexyl dimethicone, (acrylates/tridecyl acrylate/methacryl triethoxysilylpropyl acid/dimethicone methacrylate) copolymer, triethoxycaprylylsilane, and the like.
Examples of silicone oils include methylhydrogenpolysiloxane, dimethylpolysiloxane, and methylphenylpolysiloxane.
Examples of alkylsilanes include methyltrimethoxysilane, ethyltrimethoxysilane, hexyltrimethoxysilane, octyltrimethoxysilane, and the like.
Examples of fluoroalkylsilanes include trifluoromethylethyltrimethoxysilane, heptadecafluorodecyltrimethoxysilane, and the like.
Moreover, as a silicone compound, the monomer of a compound may be sufficient and a copolymer may be sufficient.
These silicone compounds may be used individually by 1 type, and may use 2 or more types together.

Examples of fatty acids include palmitic acid, isostearic acid, stearic acid, lauric acid, myristic acid, behenic acid, oleic acid, rosin acid, 12-hydroxystearic acid and the like.

Examples of fatty acid soaps include aluminum stearate, calcium stearate, aluminum 12-hydroxystearate and the like.

Examples of fatty acid esters include dextrin fatty acid esters, cholesterol fatty acid esters, sucrose fatty acid esters, starch fatty acid esters and the like.

Examples of organic titanate compounds include isopropyl triisostearoyl titanate, isopropyl dimethacrylisostearoyl titanate, isopropyl tri(dodecyl)benzenesulfonyl titanate, neopentyl(diallyl)oxy-tri(dioctyl)phosphate titanate, neopentyl(diallyl)oxy- and trineododecanoyl titanate.

According to the surface-coated titanium oxide powder of this embodiment, the photocatalytic activity of the titanium oxide particles can be sufficiently suppressed. Therefore, when the cosmetic containing the surface-coated titanium oxide powder of the present embodiment is applied to the skin, it is possible to suppress deterioration of the oil agent. In addition, according to the surface-coated titanium oxide powder of the present embodiment, when a cosmetic containing the surface-coated titanium oxide powder is applied to the skin, the titanium oxide particles are excellent in transparency in addition to hiding power. It is possible to obtain a natural finish with reduced peculiar bluishness.

[Method for producing surface-coated titanium oxide powder]
The method for producing the surface-coated titanium oxide powder of the present embodiment is not particularly limited as long as it is a method capable of forming a dense film of an inorganic material on the surface of titanium oxide.
In order to form a dense film of an inorganic material, for example, a method of slowing down the precipitation reaction rate of the inorganic material can be used.
Below, the case of surface-treating titanium oxide powder with a silicon compound and an aluminum compound will be described in detail.

The method for producing the surface-coated titanium oxide powder of the present embodiment includes the steps of suspending the titanium oxide powder in water, adding an alkali metal silicate to the suspension, and adding an acid to neutralize the suspension. , a step of depositing a silicon compound on the surface of titanium oxide particles, a step of adding an acidic aluminum compound, adding an alkali to adjust the pH to 3 or more and 5 or less and aging, and further adding an alkali to pH to 7 and a heat treatment step.
The method for producing the surface-coated titanium powder of the present embodiment includes the steps of suspending the titanium oxide powder in water, adding an alkali metal silicate to the suspension, adding an acid to neutralize the suspension, and A step of depositing a silicon compound on the surface of the titanium oxide particles, a step of adding a basic aluminum compound, adding an acid to ripen the pH to 9 or more and 11 or less, and further adding an acid to pH 7. You may have the process of adjusting and the process of heat-processing.

Examples of the acidic aluminum compound that can be used include aluminum sulfate and aluminum chloride.
As the basic aluminum compound, for example, sodium aluminate or the like can be used.

In the method for producing the surface-coated titanium oxide powder of the present embodiment, in the step of neutralizing the aluminum compound with an alkali or acid, aging is carried out within a predetermined pH range to control the precipitation reaction rate of the aluminum compound. It was found that by controlling the deposition reaction rate, a dense surface coating capable of suppressing photocatalytic activity can be achieved.

The aging time may be appropriately adjusted depending on the coating amount of the aluminum compound, and may be 50 minutes or longer, 1 hour or longer, or 2 hours or longer. Although the upper limit of the aging time is not limited, it may be 10 hours or less, 8 hours or less, 6 hours or less, or 4 hours or less.

The reaction temperature may be room temperature, or the suspension may be heated. The reaction temperature of the suspension may be 25°C, 40°C, 60°C, 80°C, or 90°C.
The alkali metal silicate or aluminum compound may be added while stirring the suspension as appropriate, or stirring may be continued after the addition.

After adjusting the pH to 7 and completing the reaction, the reaction solution is subjected to solid-liquid separation by filtration or the like, and a solid (cake) is recovered. The collected cake may be washed.
By heat-treating the collected cake, the surface-coated titanium oxide powder of the present embodiment can be obtained.

The heat treatment temperature may be a temperature at which a silicon compound or an aluminum compound can form a dense film, and may be, for example, 400° C. or higher and 800° C. or lower. In addition, you may heat-process after drying a cake.

The surface-coated titanium oxide powder may have a step of being pulverized by a pulverizer before and after the heat treatment step. In the crushing step, the surface-coated titanium oxide powder is preferably crushed so that the average secondary particle size is 1 μm or more and 10 μm or less. Examples of crushers include pin mills, hammer mills, jet mills, and impeller mills.

[Dispersion]
The dispersion liquid of the present embodiment contains the surface-coated titanium oxide powder of the present embodiment and a dispersion medium. The dispersion liquid of this embodiment contains other components as needed.
The dispersion liquid of the present embodiment may be in the form of a low-viscosity liquid or a high-viscosity paste.

The content of the titanium oxide powder in the dispersion liquid of the present embodiment is not particularly limited, and can be appropriately selected according to the purpose.

(dispersion medium)
The dispersion medium is not particularly limited as long as it can be blended in cosmetics, and can be appropriately selected according to the purpose. Examples of dispersion media include water, alcohols, esters, ethers, ketones, hydrocarbons, amides, polysiloxanes, modified polysiloxanes, hydrocarbon oils, ester oils, higher fatty acids, and higher alcohols. etc. One of these dispersion media may be used alone, or two or more thereof may be used in combination.

Examples of alcohols include methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, octanol, glycerin and the like.

Examples of esters include ethyl acetate, butyl acetate, ethyl lactate, propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate, γ-butyrolactone and the like.

Examples of ethers include diethyl ether, ethylene glycol monomethyl ether (methyl cellosolve), ethylene glycol monoethyl ether (ethyl cellosolve), ethylene glycol monobutyl ether (butyl cellosolve), diethylene glycol monomethyl ether, and diethylene glycol monoethyl ether.

Examples of ketones include acetone, methyl ethyl ketone, methyl isobutyl ketone, acetylacetone, cyclohexanone and the like.

Examples of hydrocarbons include aromatic hydrocarbons such as benzene, toluene, xylene and ethylbenzene; and cyclic hydrocarbons such as cyclohexane.

Examples of amides include dimethylformamide, N,N-dimethylacetoacetamide, N-methylpyrrolidone and the like.

Examples of polysiloxanes include chain polysiloxanes and cyclic polysiloxanes.
Examples of chain polysiloxanes include dimethylpolysiloxane, methylphenylpolysiloxane, and diphenylpolysiloxane.
Examples of cyclic polysiloxanes include octamethylcyclotetrasiloxane, decamethylcyclopentasiloxane, dodecamethylcyclohexasiloxane, and the like.

Examples of modified polysiloxanes include amino-modified polysiloxane, polyether-modified polysiloxane, alkyl-modified polysiloxane, and fluorine-modified polysiloxane.

Hydrocarbon oils include, for example, liquid paraffin, squalane, isoparaffin, branched light paraffin, petrolatum, ceresin and the like.

Ester oils include, for example, isopropyl myristate, cetyl isooctanoate, glyceryl dioctanoate, and the like.

Examples of higher fatty acids include lauric acid, myristic acid, palmitic acid, and stearic acid.

Examples of higher alcohols include lauryl alcohol, cetyl alcohol, stearyl alcohol, hexyldodecanol, isostearyl alcohol and the like.

(other ingredients)
Other components are not particularly limited as long as they do not impair the effects of the dispersion liquid of the present embodiment, and can be appropriately selected according to the purpose.
Other components include, for example, dispersants, stabilizers, water-soluble binders, thickeners, oil-soluble preservatives, ultraviolet absorbers, oil-soluble chemicals, oil-soluble pigments, oil-soluble proteins, vegetable oils, animal oils, and the like. mentioned. These components may be used individually by 1 type, and may use 2 or more types together.

The content of the dispersion medium in the dispersion liquid is not particularly limited, and can be appropriately selected according to the purpose. The content of the dispersion medium is preferably 10% by mass or more and 99% by mass or less, more preferably 20% by mass or more and 90% by mass or less, and 30% by mass with respect to the total amount of the dispersion liquid of the present embodiment. It is more preferable that the content is 80% by mass or more.

According to the dispersion liquid of the present embodiment, when a cosmetic containing the dispersion liquid of the present embodiment is applied to the skin, the phenomenon that the appearance of color differs depending on the viewing angle of the skin is suppressed. In addition, according to the dispersion liquid of the present embodiment, when a cosmetic containing titanium oxide powder is applied to the skin, in addition to the hiding power, the transparency is excellent, and the paleness peculiar to titanium oxide particles is reduced. You can get a smooth, natural finish.

[Manufacturing method of dispersion]
A method for producing the dispersion liquid of the present embodiment is not particularly limited, and a known method can be adopted. As a method for producing the dispersion of the present embodiment, for example, there is a method of mechanically dispersing the surface-coated titanium oxide powder of the present embodiment in a dispersion medium using a dispersing device to produce a dispersion. mentioned.
Dispersing devices include, for example, stirrers, rotation-revolution mixers, homomixers, ultrasonic homogenizers, sand mills, ball mills, roll mills, and the like.

[Cosmetics]
The cosmetic of this embodiment contains the surface-coated titanium oxide powder of this embodiment and a cosmetic base. The cosmetics of this embodiment contain other components as needed.

The content of the titanium oxide powder in the cosmetic is preferably 0.1% by mass or more and 50% by mass or less with respect to the entire cosmetic.

(Cosmetic base)
The cosmetic base can be appropriately selected from those commonly used in cosmetics, and examples thereof include talc and mica. One of these cosmetic bases may be used alone, or two or more thereof may be used in combination.

The content of the cosmetic base in the cosmetic is not particularly limited, and can be appropriately selected according to the purpose.

(other ingredients)
In addition to the surface-coated titanium oxide powder of the present embodiment and the cosmetic base, the cosmetic of the present embodiment may contain other components within a range that does not impair the effects of the present embodiment.

Other components can be appropriately selected from those commonly used in cosmetics. Other ingredients include, for example, solvents, oils, surfactants, moisturizers, organic UV absorbers, antioxidants, thickeners, perfumes, colorants, physiologically active ingredients, antibacterial agents, and the like. These components may be used individually by 1 type, and may use 2 or more types together.
The content of other components in the cosmetic is not particularly limited, and can be appropriately selected depending on the purpose.

The method for producing the cosmetic of the present embodiment is not particularly limited, and can be appropriately selected according to the purpose. The method for producing the cosmetic of the present embodiment includes, for example, a method of mixing surface-coated titanium oxide powder with a cosmetic base and mixing other ingredients, a method of mixing the dispersion, a method of mixing the dispersion with a cosmetic base and then mixing other ingredients, a method of mixing the dispersion with an existing cosmetic, and the like.

(form)
The form of the cosmetic of the present embodiment is not particularly limited, and can be appropriately selected depending on the purpose. Examples of the form of the cosmetic of the present embodiment include powder, solid powder, solid, liquid, gel, and the like. When the form of the cosmetic is liquid or gel, the form of dispersing the cosmetic is not particularly limited, and can be appropriately selected according to the purpose. Dispersion forms of gel cosmetics include, for example, water-in-oil (W/O) emulsions, oil-in-water (O/W) emulsions, and oil types.

Cosmetics of the present embodiment include, for example, base makeup, nail polish, lipstick, and the like. Among these, base makeup is preferred.
Base makeup includes, for example, a makeup base that is mainly used to reduce unevenness on the skin, a foundation that is mainly used to adjust the color of the skin, and a foundation that is mainly used to improve the fixation of the foundation to the skin. face powder, etc.

According to the cosmetic of the present embodiment, when applied to the skin, it is possible to suppress the phenomenon that the appearance of color varies depending on the viewing angle of the skin. Further, according to the cosmetic of the present embodiment, it is possible to reduce paleness peculiar to titanium oxide particles while having excellent hiding power and transparency.

EXAMPLES The present invention will be described in more detail with reference to examples and comparative examples below, but the present invention is not limited to the following examples.

[Example 1]
(Production of surface-coated titanium oxide powder)
30 g of titanium oxide particles (manufactured by Sumitomo Osaka Cement Co., Ltd., average primary particle size 400 nm, anatase type), 5 g of 0.1 mol/L sodium hydroxide aqueous solution, and 65 g of pure water are suspended in a high-speed stirrer to obtain titanium oxide. A slurry was prepared.
This titanium oxide slurry was charged into a 250 mL beaker, and 5 g of an aqueous sodium silicate solution of 15% by mass in terms of SiO ₂ was added dropwise while vigorously stirring in a hot water bath at 80°C. A 0.5 mol/L sulfuric acid aqueous solution was added dropwise to this titanium oxide slurry until the pH reached 5, and the slurry was aged for 1 hour.
Next, 6.6 g of a 15% by mass sodium aluminate aqueous solution in terms of Al ₂ O ₃ was added dropwise to this titanium oxide slurry. A 0.5 mol/L sulfuric acid aqueous solution was added dropwise to this titanium oxide slurry until the pH reached 10, and the slurry was aged for 1 hour. After aging, the beaker containing the titanium oxide slurry was taken out from the hot water bath at 80° C. and naturally cooled until the temperature of the titanium oxide slurry reached room temperature.
A 0.5 mol/L sulfuric acid aqueous solution was added dropwise to the cooled titanium oxide slurry until the pH reached 7.
Thereafter, the titanium oxide slurry was filtered to collect a cake, and the collected cake was washed with pure water.
The cake washed with pure water was dried at 120° C. for 12 hours and then heat-treated at 500° C. for 1 hour to obtain a surface-coated titanium oxide powder of Example 1.

[Example 2]
A surface-coated titanium oxide powder of Example 2 was obtained in the same manner as in Example 1, except that after dropping the sodium aluminate aqueous solution, the sulfuric acid aqueous solution was dropped until the pH of the titanium oxide slurry reached 9.

[Example 3]
Instead of the sodium aluminate aqueous solution, after dropping a 6.5% by mass aluminum sulfate aqueous solution in terms of Al ₂ O ₃ , a 1 mol / L sodium hydroxide aqueous solution was dropped until the pH of the titanium oxide slurry reached 4, A surface-coated titanium oxide powder of Example 3 was obtained in the same manner as in Example 1, except that a 1 mol/L sodium hydroxide aqueous solution was added dropwise to the cooled titanium oxide slurry until the pH reached 7.

[Example 4]
A surface-coated titanium oxide powder of Example 4 was obtained in the same manner as in Example 1, except that the amount of sodium silicate aqueous solution dropped was 3.6 g and the amount of sodium aluminate aqueous solution dropped was 4.5 g.

[Comparative Example 1]
A surface-coated titanium oxide powder of Comparative Example 1 was obtained in the same manner as in Example 1, except that after dropping the sodium aluminate aqueous solution, the sulfuric acid aqueous solution was dropped until the pH of the titanium oxide slurry reached 8.

[Comparative Example 2]
The amount of sodium silicate aqueous solution dropped is 3.6 g, and the amount of sodium aluminate aqueous solution dropped is 4.5 g. After dropping the sodium aluminate aqueous solution, the sulfuric acid aqueous solution is added until the pH of the titanium oxide slurry reaches 11.5. A surface-coated titanium oxide powder of Comparative Example 2 was obtained in the same manner as in Example 1 except that the powder was added dropwise.

[evaluation]
(pore volume)
The adsorption isotherms of the surface-coated titanium oxide powders of Examples 1 to 4 and Comparative Examples 1 and 2 were measured with a specific surface area measuring device (trade name: Belsorp-miniII, manufactured by Microtrac Benole). , and BJH method, the pore volume A (mL/g) up to a pore diameter of 100 nm was measured. Table 1 shows the results. The pore volume A is the pore volume (mL) per 1 g of the surface-coated titanium oxide powder.

(Content)
The surface-coated titanium oxide powders of Examples 1 to 4 and Comparative Examples 1 and 2 were analyzed using an ICP emission spectrometer (ICP-AES) (trade name: CIROS-120 EOP, manufactured by Rigaku Corporation). Contents of Ti, Si and Al were measured by the following methods.
A sample of 0.1 g was placed in a platinum crucible and heat-treated in an electric furnace at 700°C. Next, 2 g of lithium tetraborate was added to this crucible and melted in an electric furnace at 925°C.
The melted sample was placed in a tall beaker together with the platinum crucible, and 70 mL of hot water and 10 mL of nitric acid were added and stirred to melt. Using this solution as a test solution, the amounts of Ti, Si and Al were measured by ICP-AES.
Based on these measured values, Ti is converted to titanium oxide, Si is converted to silicon oxide, and Al is converted to aluminum hydroxide. Content of titanium oxide, silica, and aluminum hydroxide contained in the surface-coated titanium oxide powder Amount (mass) was calculated. Then, from these masses, the volumes of titanium oxide, silica, and aluminum hydroxide were calculated using their respective true densities.
The true density of titanium oxide was calculated as 4.2 g/cm ³ , the true density of silica as 2.7 g/cm ³ , and the true density of aluminum hydroxide as 2.4 g/cm ³ .
The densities of the inorganic materials (silica and aluminum hydroxide) were then calculated.
Then, the pore volume B (mL/g) per 1 g of the inorganic material was calculated by dividing the pore volume A by the mass fraction of the inorganic material.
Next, by multiplying the pore volume B by the density of the inorganic material, the pore volume C (mL/cm ³ ) per 1 cm ³ of the inorganic material was calculated. Table 1 shows the results.

(Photocatalytic activity)
A mixture of 3 g of surface-coated titanium oxide powder and 4 g of 1,3-butanediol was sandwiched in an assembled quartz cell for a spectrophotometer (model: AB20/UV-0.5, manufactured by GL Sciences), followed by a xenon lamp. 5000 kJ/m ² of simulated sunlight was irradiated using a compact light irradiation tester (EYE SUN-CUBE Xenon manufactured by Iwasaki Electric Co., Ltd.). The amount of simulated sunlight irradiation was confirmed by measuring light with a wavelength of 400 nm to 1050 nm using an illuminometer HD2102.2 measurement probe LP471RAD manufactured by Delta Ohm.
Chromaticity (L ^* , a ^* , b ^* ) before and after irradiation was measured with an ultraviolet-visible-near-infrared spectrophotometer (manufactured by JASCO Corporation, model number: V-770) using an integrating sphere, and the color difference ΔE = ( (ΔL ^* ) ² + (Δa ^* ) ² + (Δb ^* ) square root of ² ) was calculated. Table 1 shows the results.

From the results shown in Table 1, the surface-coated titanium oxide powders of Examples 1 to 4 exhibited lower photocatalytic activity of the titanium oxide particles than the surface-coated titanium oxide powders of Comparative Examples 1 and 2. I knew there was

In the surface-coated titanium oxide powder of the present invention, the photocatalytic activity of the titanium oxide particles is suppressed. Therefore, when it is used for base makeup cosmetics such as foundation, it is possible to suppress makeup deterioration. Moreover, since the surface-coated titanium oxide powder of the present invention is also excellent in performance as a white pigment, it can be used in industrial applications such as white ink, and has great industrial value.

Claims (7)

A titanium oxide powder surface-coated with an inorganic material,
A surface-coated titanium oxide powder, wherein the pore volume (mL/cm ³ ) per 1 cm ³ of the inorganic material is 6.0 or less when the pore volume with a pore diameter of 100 nm or less is measured. 2. The surface-coated titanium oxide powder according to claim 1, wherein said inorganic material contains at least a silicon compound and an aluminum compound. 3. The surface-coated titanium oxide powder according to claim 1, wherein the crystal phase of said titanium oxide powder is an anatase type. The surface-coated titanium oxide powder according to any one of claims 1 to 3, wherein the inorganic material accounts for 5% by volume or more and 20% by volume or less of the total volume of the titanium oxide and the inorganic material. The surface-coated titanium oxide powder according to any one of claims 1 to 4, which has an organic material on its surface. A dispersion containing the surface-coated titanium oxide powder according to any one of claims 1 to 5 and a dispersion medium. A cosmetic comprising the surface-coated titanium oxide powder according to any one of claims 1 to 5 and a cosmetic base.