JP6984407B2 - Titanium oxide powder, and dispersions and cosmetics using it - Google Patents

Description

The present invention relates to titanium oxide powder suitable for cosmetics, and dispersions and cosmetics using the same.

Titanium oxide particles are excellent in light reflection characteristics, ultraviolet shielding characteristics, and hiding power. Therefore, titanium oxide particles of submicron size to micron size are used in base makeup cosmetics such as foundations.
As titanium oxide particles suitable for cosmetics, for example, spherical anatase-type titanium oxide particles having an average particle diameter of 0.1 μm to 5 μm have been proposed (see, for example, Patent Document 1). Further, spherical rutile-type titanium oxide particles in which spherical primary particles are accumulated and whose apparent average particle diameter is 100 nm or more have also been proposed (see, for example, Patent Document 2).

Japanese Unexamined Patent Publication No. 2013-28563 Japanese Unexamined Patent Publication No. 2014-15340

However, there has been a demand for further improvement of titanium oxide particles that can reduce the paleness peculiar to titanium oxide particles while having hiding power and transparency.

The present invention has been made in view of the above circumstances, and is a titanium oxide powder and a titanium oxide powder which can reduce the paleness peculiar to titanium oxide particles while having hiding power and transparency when applied to the skin. , It is an object of the present invention to provide a dispersion liquid and a cosmetic using it.

That is, the titanium oxide powder of the present invention is a titanium oxide powder having a BET specific surface area of 5 m ² / g or more and 15 m ² / g or less, and the titanium oxide powder contains octahedral particles. The content of the octahedral particles is 50% by number or more, and 5 mL of a 10 vol% triethanolamine aqueous solution and 50 mg of titanium oxide particles are placed in a closed container having an inner diameter of 15 mm under a nitrogen atmosphere, and the wavelength is 365 nm in a suspended state. ^{The Ti 3+} density generated on the surface of the titanium oxide particles measured by irradiating with ultraviolet light is 0.1 μmol / m ² or less.

The dispersion liquid of the present invention is characterized by containing the titanium oxide powder of the present invention and a dispersion medium.

The cosmetic of the present invention is characterized by containing the titanium oxide powder of the present invention and a cosmetic base.

According to the titanium oxide powder of the present invention, a titanium oxide powder that can reduce the paleness peculiar to titanium oxide particles while having hiding power and transparency when applied to the skin, and the titanium oxide powder used therein. Dispersions and cosmetics can be provided.

According to the dispersion liquid of the present invention, when a cosmetic containing this dispersion liquid is applied to the skin, it is possible to reduce the paleness peculiar to titanium oxide particles while having a hiding power and a transparent feeling.

According to the cosmetic of the present invention, when applied to the skin, it is possible to reduce the paleness peculiar to titanium oxide particles while having a hiding power and a transparent feeling.

It is a schematic diagram which shows an example of octahedral titanium oxide particles. It is another schematic diagram which shows an example of octahedral titanium oxide particles. It is a figure which shows the scanning electron microscope image of an example of the titanium oxide particle of Example 1. FIG. It is a figure which shows the transmission electron microscope image of an example of the titanium oxide particle of Example 1. FIG. It is a figure which shows the result of simulating the state of light scattering when the spherical titanium oxide particles are irradiated with light. It is a figure which shows the result of simulating the state of light scattering when the octahedral titanium oxide particle is irradiated with light.

An embodiment of the titanium oxide powder of the present invention, and a dispersion liquid and a cosmetic using the same will be described.
It should be noted that the present embodiment is specifically described in order to better understand the gist of the invention, and is not limited to the present invention unless otherwise specified.

[Titanium oxide powder]
The titanium oxide powder of the present embodiment is a titanium oxide powder having a BET specific surface area of 5 m ² / g or more and 15 m ² / g or less, and the titanium oxide powder contains octahedral particles and has an inner diameter of 15 mm. Ti generated on the surface of titanium oxide particles measured by putting 5 mL of 10 vol% triethanolamine aqueous solution and 50 mg of titanium oxide particles in a closed container in a nitrogen atmosphere and irradiating them with ultraviolet light having a wavelength of 365 nm in a suspended state. ^{The 3+} density is 0.1 μmol / m ² or less.

(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, and ^{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, the paleness peculiar to the titanium oxide particles can be further reduced while having a hiding power and a transparent feeling. It is advantageous. Further, when the BET specific surface area of the titanium oxide powder is ^{less than 5 m 2} / g, the transparency is lowered due to light scattering. On the other hand, when the BET specific surface area of the titanium oxide powder ^{exceeds 15 m 2} / g, the light scattering intensity of a short wavelength is increased as compared with the light scattering intensity of a long wavelength, and the bluish whiteness is increased.

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 Microtrac Bell) can be mentioned. Be done.

For the titanium oxide powder of the present embodiment, 5 mL of a 10 vol% triethanolamine aqueous solution and 50 mg of titanium oxide particles are placed in a closed container having an inner diameter of 15 mm in a nitrogen atmosphere, and the particles are suspended and irradiated with ultraviolet light having a wavelength of 365 nm. ^{The Ti 3+} density generated on the surface of the titanium oxide particles measured in 1 is 0.1 μmol / m ² or less.
The Ti ³⁺ density is preferably small, but the lower limit may be, for example, 0.01 μmol / m ² , 0.02 μmol / m ² , or 0.03 μmol / m ² .
When the Ti ³⁺ density is in the above range, the hiding power when the cosmetic containing the titanium oxide powder of the present embodiment is applied to the skin is improved.
On the other hand, when the Ti ³⁺ density exceeds 0.1 μmol / m ² , the hiding power of the titanium oxide particles decreases.
It is presumed that the titanium oxide powder having a high Ti ³⁺ density has a lower refractive index than the theoretical value, and therefore has a smaller hiding power.

^{Here, the Ti 3+} density measured by the above measuring method is the sum of the amounts of defects existing inside and on the surface of titanium oxide, as described in Japanese Patent No. 5259767. In other words, the Ti ³⁺ density indicates the surface defect density. ^{The method for measuring Ti 3+} density of the present invention is the same as the method described in Japanese Patent No. 5259767.

(Titanium oxide particles)
The titanium oxide powder of this embodiment is an aggregate of titanium oxide particles.
The shape of the titanium oxide particles is octahedral.
Since the shape of the titanium oxide particles is octahedral, light can be scattered over a wide range, which improves transparency and hiding power when a cosmetic containing titanium oxide powder is applied to the skin. be able to.

The octahedron shape is a three-dimensional shape in which a space is surrounded by eight triangles, as shown in FIG.
The tips of the vertices of the octahedral titanium oxide particles (points indicated by the symbols A, B, C, D, E, and F in FIG. 1) have a sharp shape, a rounded shape, and a flat shape. It may have a shaped shape.

The content of octahedral titanium oxide particles in the titanium oxide powder is represented by the number% calculated by the method described later. That is, the content of the octahedral titanium oxide particles in the titanium oxide powder is preferably 50% by number or more, 60% by number or more, or 70% by number or more. The upper limit of the content of the octahedral titanium oxide particles in the titanium oxide powder may be 80% by number, 90% by number, or 100% by number.
When the content of octahedral titanium oxide particles in the titanium oxide powder is 50% by number or more, excellent hiding power and transparency are obtained when a cosmetic containing titanium oxide powder is applied to the skin. While having it, it is preferable in that the paleness peculiar to titanium oxide particles can be further reduced.

The content of octahedral titanium oxide particles in the titanium oxide powder, that is, the number%, is determined by observing 100 titanium oxide particles with a scanning electron microscope (SEM), for example, and 100 of these. It can be calculated by counting the number of octahedral titanium oxide particles contained in.

(A line segment connecting two vertices facing each other)
The average value of the maximum value of the line segment connecting two opposite vertices of the octahedral particles (hereinafter, may be referred to as "distance between vertices") is preferably 300 nm or more and 1000 nm or less, preferably 320 nm or more. Moreover, it is more preferably 900 nm or less, further preferably 330 nm or more and 800 nm or less, and most preferably 340 nm or more and 750 nm or less.

Octahedron particles with an average maximum distance between two vertices facing each other of 300 nm or more and 1000 nm or less can scatter visible light over a wider range than spherical and spindle-shaped titanium oxide particles. .. Therefore, it is presumed that the cosmetic containing the titanium oxide powder containing the octahedral particles can reduce the paleness peculiar to the titanium oxide particles while achieving both the hiding power and the transparency.
When the average value of the maximum value of the maximum distance between the two facing vertices of the octahedral particles is 300 nm or more and 1000 nm or less, when applied to the skin, it has an excellent transparency and is blue and white peculiar to titanium oxide particles. It is advantageous in that the particle size can be further reduced.

If the average value of the maximum value of the distance between the two vertices facing each other of the octahedral particles is less than 300 nm, short wavelength light is scattered and the color is pale, which is not preferable. On the other hand, if the average value of the maximum values of the distances between the two vertices facing each other in one octahedral particle exceeds 1000 nm, transparency cannot be obtained, which is not preferable.

The maximum value of the distance between two opposite vertices of the octahedral particle is measured by observing the octahedral particle with a scanning electron microscope (SEM). Specifically, for 100 octahedral particles, the maximum value of the distance between two vertices facing each other is measured, and the value obtained by arithmetically averaging the obtained measured values is the maximum value of the distance between the two vertices facing each other. Is the average value of.
When the tip of the apex of the octahedral particle is a flat surface, the center point of the flat surface is set as the apex, and the maximum value of the distance between the two vertices facing each other is set.

The maximum value of the line segment (major axis m of the octahedral particle in FIG. 1) connecting the two opposite vertices (point A and point B in FIG. 1) of the octahedral particle is X (nm), and the maximum value thereof. Two vertices of the octahedral particles facing each other (points C and E or points D and points in FIG. 1) substantially orthogonal to the line segment related to the value (major axis m of the octahedral particles in FIG. 1). When the minimum value of the line segment connecting F) (minor axis n, o of the octahedral particles in FIG. 1) is Y (nm), the average value of the ratio of X to Y (X / Y) is 1. It is preferably 5 or more and 3.0 or less, and more preferably 1.5 or more and 2.5 or less.

When the average value of the ratio (X / Y) is 1.5 or more and 3.0 or less, the cosmetic containing titanium oxide powder containing octahedral particles is octahedral when applied to the skin. It is advantageous in that the light scattering effect of the shaped particles can be obtained more effectively and the transparency can be further improved.

The above-mentioned substantially orthogonality means that two line segments (major axis and minor axis of octahedral particles) intersect at an angle of 70 ° to 90 °. Further, the above substantially orthogonal means that two line segments (major axis and minor axis of octahedral particles) may be close to each other and intersect, and two line segments (major axis and short axis of octahedral particles) are not necessarily required. The axis) does not have to have an intersection.

The octahedron shape is a double quadrangular pyramid in which two quadrangular pyramids share the bottom surface of a quadrangle. The octahedral shape in the present embodiment is preferably a shape in which two congruent quadrangular pyramids share the bottom surface of a square. Further, in the present embodiment, the side surface shape of the quadrangular pyramid is an isosceles triangle, not an equilateral triangle. The maximum value (X) of the distance between the two vertices facing each other of the octahedral particle is the length of the line segment that gives the distance between the two vertices existing in the direction orthogonal to the bottom surface of the square pyramid. means. Further, the minimum value (Y) of the distance between two vertices facing each other of the octahedral particles means the length of the shorter diagonal line of the two diagonal lines on the bottom surfaces of the two square pyramids.

Here, the distance between the two vertices will be described with reference to the drawings. FIG. 1 is a schematic view showing an example of octahedral titanium oxide particles in the titanium oxide particles of the present embodiment. In FIG. 1, the distance between the two vertices of the octahedral particle is the distance a between the points A and C, the distance b between the points A and D, the distance c between the points A and E, and the points A. Distance d between points F, distance e between points C and D, distance f between points D and E, distance g between points E and F, distance h between points F and C, and points B Distance i between points C, distance j between points B and D, distance k between points B and E, distance l between points B and F, distance n between points C and E, and points D There are 15 distances o between points F and m distances between points A and B. In FIG. 1, the distance between two vertices facing each other of the octahedral particles is 3 such as the distance n between the points C and E, the distance o between the points D and F, and the distance m between the points A and B. It is an individual. The maximum value of the distance between the two vertices facing each other of the octahedral particles is the distance m, which corresponds to the maximum value (X) of the distance between the two vertices facing each other of the octahedral particles. Further, in FIG. 1, the line segments connecting the two opposite vertices of the octahedral particles, which are substantially orthogonal to the line segment related to the maximum value X, are the distance n and the distance o. Of the distance n and the distance o, the shorter one corresponds to the minimum value (Y) of the distance between the two vertices facing each other of the octahedral particles.

The maximum value (X) (nm) of the distance between two facing vertices of the octahedral particle and the minimum value (Y) (nm) of the distance between the two facing vertices of the octahedral particle are, for example, scanning type. It can be measured by observing the octahedral particles using an electron microscope (SEM).

The above ratio (X / Y) is calculated by observing the titanium oxide particles using a scanning electron microscope (SEM) and measuring the above maximum value (X) and the above minimum value (Y). The ratio (X / Y) was calculated for each of the 100 octahedral titanium oxide particles, and the arithmetic mean value is the average value of the above ratio (X / Y).

(Average particle size converted from BET specific surface area)
The average particle size of the titanium oxide powder (hereinafter, also referred to as “BET-equivalent average particle size”) converted from the BET specific surface area of the titanium oxide powder is preferably 300 nm or more and 1000 nm or less, preferably 310 nm or more. Moreover, it is more preferably 800 nm or less, and further preferably 320 nm or more and 700 nm or less.
The BET-converted average particle diameter of the titanium oxide powder can be calculated by the following equation (1) when the shape of the titanium oxide particles is octahedral.
BET-converted average particle size (nm) = 16240 / (BET specific surface area (m ² / g) x ρ (g / cm ³ )) ... (1)
In the above formula (1), ρ represents the density of titanium oxide.

Even if the titanium oxide powder contains titanium oxide particles having a shape other than the octahedral particles, if the titanium oxide powder contains 50% or more of the octahedral particles, (1). ) Is used to calculate the BET-converted average particle size.

(Average value of maximum value / average particle size in BET conversion)
The value obtained by dividing the average value of the above maximum values by the average particle size of the octahedral particles converted from the BET specific surface area (average value of maximum values / average particle size converted to BET) is 0.5 or more and 2 It is preferably 5.5 or less, more preferably 0.7 or more and 1.4 or less, and even more preferably 0.8 or more and 1.3 or less.
If (average value of maximum value / average particle size in BET conversion) is less than 0.5, it is assumed that the titanium oxide particles have fine pores and the like, so that the refractive index of the particles is higher than the original value of the titanium oxide particles. It may be reduced, resulting in reduced hiding power. On the other hand, when (average value of maximum value / average particle size in BET conversion) exceeds 2.5, when a cosmetic containing titanium oxide powder is applied to the skin, the light scattering effect due to the shape of the titanium oxide particles is exhibited. It cannot be obtained and the transparency cannot be improved.

Generally, the average particle size of the octahedral particles, which is converted from the BET specific surface area, is measured by observing with an electron microscope when the octahedral particles are not aggregated, and the octahedral particles face each other. It roughly matches the arithmetic average value of the maximum value of the line connecting the two vertices.
Therefore, the closer the value of (average value of maximum value / average particle diameter in BET conversion) is to 1.0, the more the titanium oxide particles are not aggregated and the particles existing in the state of primary particles are present. It means that there are many.
On the other hand, when the primary particles aggregate to form octahedral particles, the maximum value of the line connecting the two opposite vertices of the octahedral particles, which is observed and measured with an electron microscope, is calculated. The average value does not match the average particle size converted from the BET specific surface area. Therefore, when the primary particles are aggregated to form octahedral particles, the average value of the maximum values / the average particle diameter in terms of BET exceeds 2.5.

(Crystal phase)
The crystal phase of the titanium oxide powder of the present embodiment is not particularly limited, and may be a single phase of any one of anatase type, rutile type and brookite type, or a mixed phase thereof. Among these, the crystal phase of the titanium oxide powder of the present embodiment is preferably anatase type. When the crystal phase of the titanium oxide powder is anatase type, the hiding power is further enhanced when a cosmetic containing the titanium oxide powder is applied to the skin, and when mixed with a cosmetic base, the skin of human skin It is advantageous in that a color close to the tint can be obtained.

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

(surface treatment)
The titanium oxide powder of the present embodiment may have either an inorganic compound or an organic compound on the surface.
Examples of the method of adhering either the inorganic compound or the organic compound to the surface of the titanium oxide particles include a method of surface treatment using a surface treatment agent.
The surface treatment agent is not particularly limited as long as it can be used in cosmetics, and can be appropriately selected depending on the intended purpose. Examples of the surface treatment agent include inorganic components, organic components and the like.

Examples of the inorganic component include silica and alumina.

Examples of the organic component include silicone compounds, organopolysiloxanes, fatty acids, fatty acid soaps, fatty acid esters, organic titanate compounds, surfactants, non-silicone compounds and the like. These may be used alone or in combination of two or more.

Examples of the silicone compound include silicone oils such as methylhydrogenpolysiloxane, dimethylpolysiloxane and methylphenylpolysiloxane; alkylsilanes such as methyltrimethoxysilane, ethyltrimethoxysilane, hexyltrimethoxysilane and octyltrimethoxysilane; Fluoroalkylsilanes such as trifluoromethylethyltrimethoxysilane, heptadecafluorodecyltrimethoxysilane; methicone, hydrogendimethicone, triethoxysilylethylpolydimethylsiloxyethyldimethicone, triethoxysilylethylpolydimethylsiloxyethylhexyldimethicone, (Acrylate / acrylic) Examples thereof include tridecyl acid acid / triethoxysilylpropyl methacrylate / dimethicone methacrylate) copolymer and triethoxycaprylylsilane. Further, the silicone compound may be a monomer of the compound or a copolymer. These may be used alone or in combination of two or more.

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

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

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

Examples of the organic titanate compound include isopropyltriisostearoyl titanate, isopropyldimethacrylisostearoyl titanate, isopropyltri (dodecyl) benzenesulfonyl titanate, neopentyl (diallyl) oxy-tri (dioctyl) phosphate titanate, and neopentyl (diallyl) oxy-. Examples include trineododecanoyl titanate.

According to the titanium oxide powder of the present embodiment, when a cosmetic containing the titanium oxide powder is applied to the skin, the paleness peculiar to the titanium oxide particles is reduced while achieving both hiding power and transparency. , You can get a natural finish. Further, when the cosmetic containing the titanium oxide powder of the present embodiment is applied to the skin, it is excellent in elongation and adhesion to the skin. Therefore, the titanium oxide powder of the present embodiment can be suitably used for cosmetics, and can be particularly preferably used for base makeup cosmetics.

[Manufacturing method of titanium oxide powder]
In the method for producing titanium oxide powder of the present invention, a reaction solution is prepared by mixing a hydrolysis product of titanium alkoxide or a titanium metal salt with a compound having a five-membered ring containing nitrogen, and the reaction solution is watered. It has a first step of producing titanium oxide particles by thermal synthesis. Further, the method for producing the titanium oxide powder of the present invention is the same as that of the reaction solution containing the titanium oxide particles after hydrothermal synthesis obtained in the first step and the first step before hydrothermal synthesis, if necessary. It has a second step of mixing the reaction solution and hydrothermal synthesis. Further, the method for producing titanium oxide powder of the present invention includes a step of drying the reaction solution obtained in the first step or the second step at 400 ° C. or lower.

(First step)
The first step is a step of producing titanium oxide particles.
In the first step, a reaction solution is prepared by mixing a hydrolysis product of titanium alkoxide or a titanium metal salt with a compound having a five-membered ring containing nitrogen, and the reaction solution is hydrothermally synthesized to produce titanium oxide. This is the process of generating particles.

(Hydrolyzed product of titanium alkoxide or titanium metal salt)
The hydrolyzed product of titanium alkoxide or titanium metal salt is obtained by hydrolyzing titanium alkoxide or titanium metal salt.
The hydrolysis product is, for example, a cake-like solid that is a white solid, and is titanium hydroxide-containing titanium called metatitanium acid or orthotitanium acid.

Examples of the titanium alkoxide include tetraethoxytitanium, tetraisopropoxytitanium, tetranormalpropoxytitanium, tetranormalbutoxytitanium and the like. These may be used alone or in combination of two or more. Among these, tetraisopropoxytitanium and tetranormalbutoxytitanium are preferable, and tetraisopropoxytitanium is more preferable, because they are easily available and the hydrolysis rate can be easily controlled.

Examples of the titanium metal salt include titanium tetrachloride, titanium sulfate and the like. These may be used alone or in combination of two or more.
In this embodiment, it is preferable to use high-purity titanium alkoxide or high-purity titanium metal salt in order to obtain high-purity anatase-type titanium oxide particles.

Hydrolysis products include by-products such as alcohols, hydrochloric acid and sulfuric acid.
Since the by-product inhibits nucleation and crystal growth of titanium oxide particles, it is preferable to wash the hydrolysis product with pure water.
Examples of the method for cleaning the hydrolysis product include decantation, a nutche method, and an ultrafiltration method.

(Compound with a five-membered ring containing nitrogen)
A compound having a five-membered ring containing nitrogen is included in the reaction solution because of its function as a pH adjuster for the reaction solution and as a catalyst for hydrothermal synthesis.
Compounds having a five-membered ring containing nitrogen include, for example, pyrrole, imidazole, indol, purine, pyrrolidine, pyrazole, triazole, tetrazole, isothiazole, isoxazole, furazan, carbazole, 1,5-diazabicyclo- [4.3. .0] -5-Nonen and the like. These may be used alone or in combination of two or more.

Among these, the compound having a five-membered ring containing nitrogen is a compound containing one nitrogen atom because the particle size distribution of the titanium oxide powder can be narrowed and the crystallinity can be further improved. Preferred are, for example, pyrrole, indole, pyrrolidine, isothiazole, isoxazole, furazan, carbazole, and 1,5-diazabicyclo- [4.3.0] -5-nonen.
Among these, the compound having a five-membered ring containing nitrogen contains one nitrogen atom and has a five-membered ring because the particle size distribution of the titanium oxide powder can be narrowed and the crystallinity can be further improved. Is more preferably a compound having a saturated heterocyclic structure, for example, pyrrolidine, 1,5-diazabicyclo- [4.3.0] -5-nonene is more preferable.

The method for preparing the reaction solution is not particularly limited and may be appropriately selected depending on the intended purpose. For example, a method of mixing using a stirrer, a bead mill, a ball mill, an attritor, a dissolver, or the like can be mentioned.

Further, water may be added to the reaction solution to adjust the concentration of the reaction solution. Examples of the water added to the reaction solution include deionized water, distilled water, pure water and the like.

The pH of the reaction solution is preferably 9 or more and 13 or less, and 11 or more and 13 or less, from the viewpoint that the catalytic action of the compound having a five-membered ring containing nitrogen functions appropriately and the nucleation rate becomes appropriate. Is more preferable.
When the pH of the reaction solution is in the range of 9 or more and 13 or less, the efficiency of producing titanium oxide particles and crystal growth is improved.
The pH of the reaction solution can be adjusted by controlling the content of the compound having a five-membered ring containing nitrogen.

The titanium atom concentration in the reaction solution can be appropriately selected depending on the size of the target titanium oxide particles, but is preferably 0.05 mol / L or more and 3.0 mol / L or less, and is 0. It is more preferably 5.5 mol / L or more and 2.5 mol / L or less.
When the titanium atom concentration in the reaction solution is 0.05 mol / L or more and 3.0 mol / L or less, the nucleation rate is appropriate, so that the efficiency of producing titanium oxide particles and crystal growth is improved.
The titanium atom concentration in the reaction solution can be adjusted by controlling the content of the hydrolysis product of titanium alkoxide or titanium metal salt.

The molar ratio of the titanium atom to the compound having a five-membered ring containing nitrogen (titanium atom: the compound having a five-membered ring containing nitrogen) in the reaction solution was 1.0: 1.0 to 1.0: 5. It is preferably 0, more preferably 1.0: 1.1 to 1.0: 4.0, and even more preferably 1.0: 1.2 to 1.0: 3.0. ..
When the molar ratio of the titanium atom to the compound having a five-membered ring containing nitrogen in the reaction solution is in the above range, octahedral titanium oxide particles having ^{a Ti 3+} density of 0.1 μmol / m ^{2 or less are produced.} Can be made.

Hydrothermal synthesis is a method in which a reaction solution is heated and titanium in the reaction solution is reacted in the presence of hot water at high temperature and high pressure.
Hydrothermal synthesis is carried out by putting the reaction solution in a high-temperature and high-pressure container called an autoclave, sealing it, and heating the whole autoclave.
When the reaction solution is heated, the water in the reaction solution evaporates and the pressure in the container rises, so that a high-temperature and high-pressure reaction can be carried out.

The heat holding temperature in hydrothermal synthesis is preferably 150 ° C. or higher and 350 ° C. or lower, and more preferably 150 ° C. or higher and 210 ° C. or lower.
When the heat holding temperature in hydrothermal synthesis is within the above range, the solubility of the hydrolysis product of titanium alkoxide or titanium metal salt in water is improved, and the titanium alkoxide or titanium metal salt can be dissolved in the reaction solution. In addition, a nucleus of titanium oxide particles can be generated, the nucleus can be grown, and titanium oxide particles having a desired shape can be produced.

The heating rate in hydrothermal synthesis is not particularly limited and can be appropriately selected depending on the intended purpose.
The pressure in hydrothermal synthesis is the pressure when the reaction solution is heated to the above temperature range in a high-temperature and high-pressure container.

During heating in the autoclave, it is preferable to stir the reaction solution using a stirrer.
The stirring speed is not particularly limited and may be appropriately selected depending on the intended purpose, but is preferably 100 rpm or more and 300 rpm or less.

The heating retention time in hydrothermal synthesis is not particularly limited and can be appropriately selected depending on the size of the titanium oxide particles to be produced, but is preferably 3 hours or longer, more preferably 4 hours or longer.
If the heat retention time is less than 3 hours, the hydrolysis product of the raw material titanium alkoxide or titanium metal salt may not react and the yield may decrease.

The heat retention time is affected by the type and concentration of the raw material. Therefore, a preliminary experiment may be carried out as appropriate, and the heating and holding time may be set so that the titanium oxide particles have a desired size. For example, the heat holding time may be 9 hours, 12 hours, 24 hours, 48 hours, or 72 hours. However, from the viewpoint of production efficiency, heating may be stopped when the titanium oxide particles reach a desired size.

(Second step)
The second step is a step of crystal growing the titanium oxide particles obtained in the first step. The second step is performed when the size of the obtained titanium oxide particles is smaller than desired.
In the second step, the reaction solution containing the titanium oxide particles after hydrothermal synthesis obtained in the first step and the same reaction solution as in the first step before hydrothermal synthesis (hydrolysis product of titanium alkoxide or titanium metal salt). , And a compound having a five-membered ring containing nitrogen), which is a step of hydrothermal synthesis.

A reaction solution containing titanium oxide particles after hydrothermal synthesis obtained in the first step and the same reaction solution as in the first step before hydrothermal synthesis (hydrogenated product of titanium alkoxide or titanium metal salt, and nitrogen) are contained. The mixing ratio with the compound having a five-membered ring) is preferably 1: 1 to 1:20 in terms of the mass of the titanium oxide particles.

The hydrothermal synthesis in the second step can be performed under the same conditions as in the first step.

If it is desired to further increase the size of the titanium oxide particles obtained in the second step, the reaction solution containing the titanium oxide particles obtained in the second step after hydrothermal synthesis is the same as in the first step before hydrothermal synthesis. A reaction solution (a hydrolysis product of titanium alkoxide or a titanium metal salt, and a compound having a five-membered ring containing nitrogen) may be mixed and hydrothermally synthesized under the same conditions as in the first step. Further, the same step may be repeated until titanium oxide particles having a desired size are obtained.

(Third step)
The method for extracting the titanium oxide powder from the reaction solution after performing the first step or the second step is not particularly limited, and can be appropriately selected depending on the intended purpose. Examples of the method for taking out titanium oxide from the reaction solution include a method for solid-liquid separation such as decantation and a nutche method.

After taking out the titanium oxide powder, the obtained titanium oxide powder may be washed with pure water or the like for the purpose of reducing impurities.
The titanium oxide powder taken out by solid-liquid separation may be naturally dried, or may be heated at 400 ° C. or lower and dried.
The lower limit of the heating temperature of the titanium oxide powder is not particularly limited as long as the titanium oxide powder can be dried. For example, it may be 200 ° C., 250 ° C., or 300 ° C.
By drying the titanium oxide powder at 400 ° C. or lower, it is possible to obtain a titanium oxide powder having excellent elongation and adhesion to the skin when applied to the skin.
When the drying temperature becomes high, the titanium oxide particles are fused to each other and the feel when applied to the skin is deteriorated, which is not preferable.
The titanium oxide powder of the present embodiment can be obtained by taking out the titanium oxide powder from the reaction solution after hydrothermal synthesis and drying it at 400 ° C. or lower.

It is also possible to perform surface treatment on the titanium oxide powder. The time for performing the surface treatment is not particularly limited, and can be appropriately selected according to the purpose. Examples of the time for performing the surface treatment include after the first step and after the second step.
The surface treatment method is not particularly limited, and a known method can be appropriately selected depending on the type of surface treatment agent to be used.

[Dispersion]
The dispersion liquid of the present embodiment contains the titanium oxide powder of the present embodiment and the dispersion medium. The dispersion liquid of the present embodiment contains other components as necessary.
The dispersion liquid of the present embodiment may be 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 depending on the intended purpose.

(Dispersion medium)
The dispersion medium is not particularly limited as long as it can be blended in cosmetics, and can be appropriately selected depending on the intended purpose. Examples of the dispersion medium include water, alcohols, esters, ethers, ketones, hydrocarbons, amides, polysiloxanes, modified products of polysiloxanes, hydrocarbon oils, ester oils, higher fatty acids, and higher alcohols. And so on. These may be used alone or in combination of two or more.

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

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

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

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

Examples of the polysiloxanes include chain polysiloxanes such as dimethylpolysiloxane, methylphenylpolysiloxane, and diphenylpolysiloxane; cyclic polysiloxanes such as octamethylcyclotetrasiloxane, decamethylcyclopentasiloxane, and dodecamethylcyclohexanesiloxane. And so on.

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

Examples of the hydrocarbon oil include liquid paraffin, squalane, isoparaffin, branched chain light paraffin, petrolatum, selecin and the like.

Examples of the ester oil include isopropyl myristate, cetyl isooctanoate, glyceryl trioctanoate and the like.

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

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

(Other ingredients)
The other components are not particularly limited as long as they do not impair the effect of the dispersion liquid of the present embodiment, and can be appropriately selected depending on the intended purpose. Other components include, for example, dispersants, stabilizers, water-soluble binders, thickeners, oil-soluble preservatives, UV absorbers, oil-soluble agents, oil-soluble pigments, oil-soluble proteins, vegetable oils, animal oils and the like. Can be mentioned. These may be used alone or in combination of two or more.

The content of the dispersion medium is not particularly limited and can be appropriately selected depending on the intended 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, more preferably 30% by mass or less, based on the total amount of the dispersion liquid of the present embodiment. It is more preferably mass% or more and 80% by mass or less.

According to the dispersion liquid of the present embodiment, when the cosmetic containing the dispersion liquid of the present embodiment is applied to the skin, the paleness peculiar to the titanium oxide particles is reduced while achieving both hiding power and transparency. , You can get a natural finish. Further, when the cosmetic containing the titanium oxide powder of the present embodiment is applied to the skin, it is excellent in elongation and adhesion to the skin. Therefore, the dispersion liquid of the present embodiment can be suitably used for cosmetics, and can be particularly preferably used for base makeup cosmetics.

[Manufacturing method of dispersion]
The method for producing the dispersion liquid of the present embodiment is not particularly limited, and a known method can be adopted. Examples of the method for producing the dispersion liquid of the present embodiment include a method of mechanically dispersing the titanium oxide powder of the present embodiment with a dispersion medium by a disperser to produce a dispersion liquid. ..
Examples of the disperser include a stirrer, a self-revolving mixer, a homomixer, an ultrasonic homogenizer, a sand mill, a ball mill, a roll mill and the like.

When applied to the skin, the dispersion liquid of the present embodiment can reduce the paleness peculiar to titanium oxide while achieving both hiding power and transparency. Further, when the cosmetic containing the titanium oxide powder of the present embodiment is applied to the skin, it is excellent in elongation and adhesion to the skin.

[Cosmetics]
The cosmetic of the present embodiment contains the titanium oxide powder of the present embodiment and a cosmetic base. The cosmetic of this embodiment contains other ingredients 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 usually used for cosmetics, and examples thereof include talc and mica. These may be used alone or in combination of two or more.

The content of the cosmetic base in the cosmetics is not particularly limited and can be appropriately selected depending on the intended purpose.

(Other ingredients)
The cosmetic of the present embodiment may contain other components other than the titanium oxide powder of the present embodiment and the cosmetic base as long as the effects of the present embodiment are not impaired.

Other ingredients can be appropriately selected from those usually used in cosmetics. Examples of other components include solvents, oils, surfactants, moisturizers, organic ultraviolet absorbers, antioxidants, thickeners, fragrances, colorants, bioactive components, antibacterial agents and the like. These may be used alone or in combination of two or more.
The content of other components in the cosmetics is not particularly limited and can be appropriately selected depending on the intended purpose.

The method for producing the cosmetics of the present embodiment is not particularly limited, and can be appropriately selected depending on the intended purpose. The method for producing cosmetics according to the present embodiment is, for example, a method of mixing titanium oxide powder with a cosmetic base and mixing other components to produce cosmetics, or mixing titanium oxide powder with existing cosmetics. Examples thereof include a method of manufacturing, a method of mixing a dispersion liquid with a cosmetic base and mixing other components, and a method of mixing a dispersion liquid with an existing cosmetic product.

(form)
The form of the cosmetic of the present embodiment is not particularly limited and can be appropriately selected depending on the intended purpose. Examples of the form of the cosmetic of the present embodiment include powder, powder solid, solid, liquid, gel and the like. When the form of the cosmetic is liquid or gel, the dispersed form of the cosmetic is not particularly limited and can be appropriately selected depending on the purpose. Examples of the dispersion form of the gel-like cosmetics include a water-in-oil (W / O-type) emulsion, an oil-in-water (O / W-type) emulsion, and an oil-type.

Examples of the cosmetics of this embodiment include base make-up, manicure, lipstick and the like. Among these, base makeup is preferable.
As base makeup, for example, it is used as a makeup base mainly used for reducing unevenness of the skin, a foundation mainly used for adjusting the color of the skin, and mainly for improving the fixation of the foundation on the skin. Examples include face powder and the like.

According to the cosmetic of the present embodiment, when applied to the skin, it is possible to reduce the paleness peculiar to titanium oxide particles while having a hiding power and a transparent feeling. Further, when the cosmetic containing the titanium oxide powder of the present embodiment is applied to the skin, it is excellent in elongation and adhesion to the skin.

Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited to the following Examples.

[Example 1]
(Preparation of titanium oxide powder)
Put 1 L of pure water in a glass container with a capacity of 2 L, add 1 mol of tetraisopropoxytitanium (trade name: A-1, manufactured by Nippon Soda Co., Ltd.) while stirring, and suspend white as a hydrolysis product of titanium alkoxide. Obtained liquid.
Next, the white suspension was solid-liquid separated to obtain a white cake (1 mol in terms of titanium oxide) which is a solid portion of the hydrolysis product of titanium alkoxide.
Next, put pyrrolidine (manufactured by Kanto Chemical Co., Inc.) in an amount of 1.4 mol and the obtained white cake in an autoclave, add pure water to make a total amount of 1 kg, hold at 220 ° C. for 9 hours, and oxidize. A reaction solution containing titanium particles was obtained.
The reaction solution containing the titanium oxide particles was separated into solid and liquid, and the solid was dried at 300 ° C. to obtain the titanium oxide powder of Example 1.

(Measurement of shape)
"Measurement of a line segment connecting two vertices facing each other"
In FIG. 2, the maximum value of a line segment connecting two facing vertices in one particle (hereinafter referred to as (X)) and two facing vertices substantially orthogonal to the line segment related to the maximum value are connected. Regarding the minimum value of the line segment (hereinafter referred to as (Y)), the titanium oxide particles of Example 1 were used using a scanning electron microscope (SEM) (trade name: S-4800, manufactured by Hitachi High-Technologies Co., Ltd.). It was measured by observing the secondary electron image of. The SEM image is shown in FIG.
Observing 100 titanium oxide particles of Example 1, the average value of (X) above, the average value of (Y) above, and the average value of the ratio (X / Y) of (X) to (Y) were obtained. Calculated. As a result, the average value of (X) was 400 nm, and the average value of the ratio (X / Y) was 2.0.
In addition, 70% by number of octahedral titanium oxide particles were present in the titanium oxide powder. The results are shown in Table 1.

(Measurement of BET specific surface area and average particle size converted from BET specific surface area)
The BET specific surface area of the titanium oxide powder of Example 1 was measured using a specific surface area meter (trade name: BELSORP-mini, manufactured by Nippon Bell Co., Ltd.). As a result, the BET specific surface area of the titanium oxide powder of Example 1 was 11 m ² / g.
The average particle size converted from the BET specific surface area of the titanium oxide powder of Example 1 was calculated by the following equation (1). As a result, the average particle size in terms of BET was 369 nm. The results are shown in Table 1.
BET-converted average particle size (nm) = 16240 / (BET specific surface area (m ² / g) x ρ (g / cm ³ )) ... (1)
In the above formula (1), ρ represents the density of titanium oxide, and ρ = 4 g / cm ³ .
The value obtained by dividing the average value of (X) by the BET-converted average particle size (hereinafter, may be referred to as “the average value of (X) / BET-converted average particle size”) was 1.1.

"Identification of the shape of titanium oxide particles"
The titanium oxide powder of Example 1 was observed with a transmission electron microscope (TEM) (model number: H-800, manufactured by Hitachi High-Technologies Corporation). The TEM image is shown in FIG. Octahedron-shaped titanium oxide particles were also observed in the TEM image.

(Identification of crystal phase of titanium oxide particles)
The crystal phase of the titanium oxide powder of Example 1 was identified using an X-ray diffractometer (trade name: X'Pert PRO, manufactured by Spectris Co., Ltd.). As a result, the titanium oxide powder of Example 1 was anatase single phase. The results are shown in Table 1.

(Crystallinity of titanium oxide particles)
5 mL of a 10 vol% triethanolamine aqueous solution and 50 mg of the titanium oxide powder of Example 1 were placed in a closed container having an inner diameter of 15 mm under a nitrogen atmosphere and suspended. In this suspended state, ultraviolet light having a wavelength of 365 nm was irradiated with an illuminance of ^{15 mW / cm 2 for 48 hours.} 50 μL of a 1 mol / L methylviologen aqueous solution was added thereto, and the added solution was centrifuged, and then the absorbance of the obtained solution at 606 nm was measured. An extinction coefficient of MV ⁺ · radicals and 13700mol ^-1 Lcm ^-1, was calculated ^{Ti 3+} density of the titanium oxide powder surface. As a result, the Ti ³⁺ density was 0.08 μmol / m ² .

"Making makeup"
2 g of titanium oxide powder of Example 1 and 8 g of talc were mixed to prepare a base make-up cosmetic of Example 1.

(Evaluation of paleness, transparency, and hiding power)
The base make-up cosmetic of Example 1 was applied to a 5 cm square substrate (trade name: HELIOPLATE HD-6, manufactured by Helioscreen) so as to be 12 mg to 14 mg to prepare a coated substrate.
Using a spectrophotometer (model number; UV-3150, manufactured by Shimadzu Corporation), the diffuse transmission spectrum (TT), diffuse reflection spectrum (TR), and linear reflection spectrum (R) of the coated substrate were measured, and the following It was evaluated using an index. In each case, the incident direction of light was measured from the coated surface, and the reflection spectrum was measured with reference to a molded plate obtained by compressing barium sulfate powder (special grade manufactured by Kanto Chemical Co., Inc.).
The results are shown in Table 1.

(Pale)
The ratio (TR _{450 nm} / TR _{550 nm ) of the diffuse reflectance at 450 nm} (TR 450 nm) and the diffuse reflectance at _{550 nm} (TR 550 nm) was used as an index of paleness. Since it can be said that the larger the ratio is, the paler it _{is, the smaller the value of TR 450 nm} / TR _{550 nm} is, the more preferable it is.
Table 2 shows the correlation between the index of paleness and the appearance of a person.

(Clarity)
The ratio (R _{550 nm} / TR _{550 nm} ) of the linear reflectance (R _{550 nm} ) at 550 nm and the diffuse reflectance (TR ₅₅₀ nm) at 550 nm was used as an index of transparency. The smaller the ratio, the higher the transparency, and the smaller the value, the more preferable.
Table 2 shows the correlation between the index of transparency and the appearance of a person.

(Concealment power)
The diffuse reflectance at 550 nm (TR _{550 nm} ) was used as an index of the hiding power. If it is large, it can be said that the hiding power is large, so a large value is preferable.
Table 2 shows the correlation between the index of hiding power and the appearance of a person.

[Example 2]
Titanium oxide powder of Example 2 was obtained in the same manner as in Example 1 except that the blending amount of pyrrolidine was 2.1 mol.

The BET specific surface area, shape, crystal phase, and crystallinity of the obtained titanium oxide powder of Example 2 were measured in the same manner as in Example 1.
As a result, the BET specific surface area was 10 m ² / g, and the BET-equivalent average particle size was 406 nm. The average value of (X) was 400 nm, the average value of (X) / BET-converted average particle size was 1.0, and the average value of the ratio (X / Y) was 2.0. The results are shown in Table 1.
Further, in the titanium oxide particles of Example 2, the octahedral titanium oxide particles are 70% by number with respect to all the particles, the crystal phase of the titanium oxide powder is an anatase single phase, and the Ti ³⁺ density is. It was 0.07 μmol / m ^2. The results are shown in Table 1.

Instead of using the titanium oxide powder of Example 1, the base make-up cosmetic of Example 2 was obtained in the same manner as in Example 1 except that the titanium oxide powder of Example 2 was used.
The paleness, transparency, and hiding power were evaluated in the same manner as in Example 1. The results are shown in Table 1.

[Example 3]
The titanium oxide powder of Example 3 and the base make-up cosmetic of Example 3 were obtained in the same manner as in Example 1 except that the temperature was maintained at 260 ° C. instead of the temperature of 220 ° C.

The BET specific surface area, shape, crystal phase, and crystallinity of the obtained titanium oxide powder of Example 3 were measured in the same manner as in Example 1.
As a result, the BET specific surface area was 9 m ² / g, and the BET-equivalent average particle size was 451 nm. The average value of (X) was 420 nm, the average value of (X) / BET-converted average particle size was 0.9, and the average value of the ratio (X / Y) was 2.0. The results are shown in Table 1.
Further, in the titanium oxide particles of Example 3, the octahedral titanium oxide particles are 70% by number with respect to all the particles, the crystal phase of the titanium oxide powder is an anatase single phase, and the Ti ³⁺ density is. It was 0.05 μmol / m ^2. The results are shown in Table 1.

Further, in the same manner as in Example 1, the paleness, transparency, and hiding power of the base makeup cosmetics of Example 3 were evaluated. The results are shown in Table 1.

[Example 4]
In an autoclave, 100 g (titanium oxide 8 g) of a reaction solution containing titanium oxide particles obtained in the production process of Example 3 and a white cake (1 mol (80 g) in terms of titanium oxide) obtained in the production process of Example 1 were added. 2.1 mol of pyrrolidine was added, pure water was added to make the total amount 1 kg, and the mixture was stirred to prepare a mixed solution.
Next, the mixed solution was held at 260 ° C. for 9 hours to crystallize the titanium oxide particles, and a reaction solution containing the titanium oxide particles was obtained.
Next, the reaction solution containing the obtained titanium oxide particles was separated into solid and liquid, and the solid was dried at 200 ° C. to obtain the titanium oxide powder of Example 4.

The BET specific surface area, shape, crystal phase, and crystallinity of the obtained titanium oxide powder of Example 4 were measured in the same manner as in Example 1.
As a result, the BET specific surface area was 6 m ² / g, and the BET-equivalent average particle size was 677 nm. The average value of (X) was 740 nm, the average value of (X) / BET-converted average particle size was 0.9, and the average value of the ratio (X / Y) was 1.1. The results are shown in Table 1.
Further, in the titanium oxide particles of Example 4, the octahedral titanium oxide particles are 70% by number with respect to all the particles, the crystal phase of the titanium oxide powder is an anatase single phase, and the Ti ³⁺ density is. It was 0.05 μmol / m ^2. The results are shown in Table 1.

Further, in the same manner as in Example 1, the paleness, transparency, and hiding power of the base makeup cosmetics of Example 4 were evaluated. The results are shown in Table 1.

[Comparative Example 1]
Similar to Example 1, the titanium oxide powder of Comparative Example 1 and Comparative Example were used in the same manner as in Example 1 except that 0.7 mol of pyrrolidine was used instead of 1.4 mol and the solid was dried at 200 ° C instead of dried at 300 ° C. Obtained 1 base make-up cosmetic.

The BET specific surface area, shape, crystal phase, and crystallinity of the obtained titanium oxide powder of Comparative Example 1 were measured in the same manner as in Example 1.
As a result, the BET specific surface area was 13 m ² / g, and the BET-equivalent average particle size was 312 nm. The average value of (X) was 350 nm, the average value of (X) / BET-converted average particle was 1.1, and the average value of the ratio (X / Y) was 2.0. The results are shown in Table 1.
Further, in the titanium oxide particles of Comparative Example 1, the octahedral titanium oxide particles are 70% by number with respect to all the particles, the crystal phase of the titanium oxide powder is an anatase single phase, and the Ti ³⁺ density is. It was 0.12 μmol / m ^2. It was. The results are shown in Table 1.

Further, in the same manner as in Example 1, the paleness, transparency, and hiding power of the base makeup cosmetics of Comparative Example 1 were evaluated. The results are shown in Table 1.

[Comparative Example 2]
In an autoclave, 100 g (titanium oxide 8 g) of a reaction solution containing titanium oxide particles obtained in the production process of Comparative Example 1 and a white cake (1 mol (80 g) in terms of titanium oxide) obtained in the production process of Example 1 were added. 0.7 mol of pyrrolidine was added, pure water was added to make the total amount 1 kg, and the mixture was stirred to prepare a mixed solution.
Next, the mixed solution was held at 220 ° C. for 9 hours to crystallize the titanium oxide particles, and a reaction solution containing the titanium oxide particles was obtained.
In an autoclave, 100 g of the obtained reaction solution (8.8 g of titanium oxide), a white cake (1 mol (80 g) in terms of titanium oxide) obtained in the production process of Example 1, and 0.7 mol of pyrrolidine were placed and pure. Water was added to make the total amount 1 kg, and the mixture was stirred to prepare a mixed solution.
Next, the mixed solution was held at 220 ° C. for 9 hours to obtain a reaction solution containing titanium oxide particles.
Next, the reaction solution containing the obtained titanium oxide particles was solid-liquid separated and dried at 200 ° C. to obtain the titanium oxide powder of Comparative Example 2.

Instead of using the titanium oxide powder of Example 1, the base make-up cosmetic of Comparative Example 2 was obtained in the same manner as in Example 1 except that the titanium oxide powder of Comparative Example 2 was used.

The BET specific surface area, shape, crystal phase, and crystallinity of the obtained titanium oxide powder of Comparative Example 2 were measured in the same manner as in Example 1.
As a result, the BET specific surface area was 6 m ² / g, and the BET-equivalent average particle size was 677 nm. The average value of (X) was 740 nm, the average value of (X) / BET-converted average particle size was 1.1, and the average value of the ratio (X / Y) was 2.0. The results are shown in Table 1.
Further, in the titanium oxide particles of Comparative Example 2, the octahedral titanium oxide particles are 60% by number with respect to all the particles, the crystal phase of the titanium oxide powder is an anatase single phase, and the Ti ³⁺ density is. It was 0.11 μmol / m ^2. The results are shown in Table 1.

Further, in the same manner as in Example 1, the paleness, transparency, and hiding power of the base makeup cosmetics of Comparative Example 2 were evaluated. The results are shown in Table 1.

[Comparative Example 3]
Commercially available titanium oxide particles having an average diameter of 300 nm and a BET specific surface area of 6 m ² / g, which are spherical rutile type particles, were used as the titanium oxide particles of Comparative Example 3.
Further, the BET-converted average particle size was calculated by the following equation (2). As a result, the BET-equivalent average particle size was 250 nm, and the value obtained by dividing the average particle size by the BET-equivalent average particle size was 1.2.
BET-converted average particle size (nm) = 6000 / (BET specific surface area (m ² / g) x ρ (g / cm ³ )) ... (2)
In the above formula (2), ρ represents the density of titanium oxide, so ρ = 4 g / cm ³ . The average particle diameter converted from the BET specific surface area of the spherical particles roughly matches the average particle diameter of the primary particles.
Further, in the titanium oxide particles of Comparative Example 3, the average value of (X) is 300 nm, the average value of (X) / BET-converted average particle diameter is 1.2, and the average value of the ratio (X / Y). Was 1.0. The results are shown in Table 1.
In the spherical titanium oxide particles, the diameter at an arbitrary position corresponds to the maximum value (X) of the line segment connecting the two facing vertices in one particle. In spherical titanium oxide particles, the minimum value (Y) of the line segment connecting two facing vertices, in which the other diameter substantially orthogonal to the diameter at an arbitrary position is substantially orthogonal to the line segment related to the maximum value (X). Corresponds to.
In addition, the content of the octahedral titanium oxide particles in the titanium oxide particles of Comparative Example 3 was 0% by number with respect to all the particles. The results are shown in Table 1.

Instead of using the titanium oxide powder of Example 1, the base make-up cosmetic of Comparative Example 3 was obtained in the same manner as in Example 1 except that the titanium oxide powder of Comparative Example 3 was used.
The paleness, transparency, and hiding power were evaluated in the same manner as in Example 1. The results are shown in Table 1.

[Comparative Example 4]
The primary particles are rotary ellipses with an average major axis of 100 nm and an average minor axis of 30 nm, and they aggregate to have an average major axis (average aggregate minor axis) of 300 nm, an average minor axis (average aggregate minor axis) of 136 nm, and an aggregate major axis / Commercially available titanium oxide particles having a spindle shape with an average aggregate minor axis of 2.2 and ^{a rutile type having a BET specific surface area of 21 m 2} / g were used as the titanium oxide powder of Comparative Example 4.
Since the shape of the primary particle is a spheroid, the BET-converted average particle diameter was calculated as P = 50 nm (100 nm ÷ 2) and Q = 3.33 (100 ÷ 30) by the following equation (3). As a result, the average particle size in terms of BET was 100 nm.
BET specific surface area (m ² / g) = 1000 × (1 + P / ((1- (1- (1 / Q) ² )) ^1/2 × P × (1- (1 / Q) ² ) ^1/2 × sin ^-1 ((1- (1 / Q) ² ) ^1/2 )) / (2 x ρ x P / 3) ... (3)
In the above formula (3), ρ represents the density of titanium oxide, and ρ = 4 g / cm ³ .
Further, in the above equation (3), P represents the radius (nm) of the average major axis of the spheroid which is the primary particle, and Q represents the radius of the major axis (major axis of the primary particle / 2) of the minor axis. It represents the average value of the aspect ratio divided by the radius (minor axis of the primary particle / 2).
Further, in the titanium oxide particles of Comparative Example 4, the average value of (X) is 300 nm, the average value of (X) / BET-converted average particle diameter is 3.0, and the average value of the ratio (X / Y). Was 2.2. The results are shown in Table 1.
Since the spindle-shaped titanium oxide particles of Comparative Example 4 are aggregated, the average major axis (average aggregated major axis) corresponds to the maximum value (X) and is substantially orthogonal to the line segment related to the maximum value (X). , The average minor axis (average aggregate minor axis) corresponds to the minimum value (Y).
The value obtained by dividing the agglomeration major axis by the BET-equivalent average particle diameter was 3.0. The results are shown in Table 1.
Since the titanium oxide particles of Comparative Example 4 are aggregated, the major axis of the aggregate and the average particle diameter converted from the BET specific surface area deviate from each other, and the major axis of the aggregate / the average particle diameter converted to BET is 2.5. The result exceeded.
In addition, the content of the octahedral titanium oxide particles in the titanium oxide particles of Comparative Example 4 was 0% by number with respect to all the particles. The results are shown in Table 1.

Instead of using the titanium oxide powder of Example 1, the base make-up cosmetic of Comparative Example 4 was obtained in the same manner as in Example 1 except that the titanium oxide powder of Comparative Example 4 was used.
The paleness, transparency, and hiding power were evaluated in the same manner as in Example 1. The results are shown in Table 1.

By comparing Examples 1 to 4 with Comparative Example 3 and Comparative Example 4, it was confirmed that the titanium oxide powder containing the octahedral particles was excellent in paleness, transparency, and hiding power.
Further, by comparing Examples 1 to 4 with Comparative Example 1 and Comparative Example 2, the ^{titanium oxide powder having a Ti 3+} density of 0.1 μmol / m ² or less has a titanium oxide particle size. It was confirmed that the hiding power was excellent even at the same level.
Therefore, it has been clarified that the titanium oxide powder of the present embodiment is suitable for cosmetics for base makeup.

The following simulation was performed to confirm that the octahedral titanium oxide particles can scatter light over a wide range.
Light scattering when spherical titanium oxide particles with a diameter of 500 nm and octahedral titanium oxide particles with a maximum distance between two facing vertices of one particle of 500 nm are irradiated with light having a wavelength of 700 nm. The situation was simulated by the FDTD method (Finite-difference time-domain method). The simulation results for the spherical titanium oxide particles are shown in FIG. Further, FIG. 6 shows the simulation results of the octahedral titanium oxide particles.
In FIGS. 5 and 6, it is assumed that the titanium oxide particles are present in the center of the square display surface. Therefore, in this simulation, it can be said that the degree of scattering is large when the light irradiating the titanium oxide particles existing in the center with light spreads more (widely) on the display surface. On the other hand, in this simulation, it can be said that the degree of scattering is small when the light irradiating the titanium oxide particles existing in the center with light does not spread or the spread is small on the display surface.
From the results of FIGS. 5 and 6, it was confirmed that the octahedral titanium oxide particles scatter light to a distance about twice as long as that of the spherical titanium oxide particles. This result shows that by making the shape of the particles octahedral, light can be scattered over a wide range, and both hiding power and transparency can be achieved.

The titanium oxide powder of the present invention has a BET specific surface area of 5 m ² / g or more and 15 m ² / g or less, and the titanium oxide powder contains octahedral particles and is placed in a closed container having an inner diameter of 15 mm under a nitrogen atmosphere. ^{The density of Ti 3+} produced on the surface of titanium oxide particles measured by irradiating ultraviolet light with a wavelength of 365 nm in a suspended state containing 5 mL of a 10 vol% triethanolamine aqueous solution and 50 mg of titanium oxide particles is 0.1 μmol. Since it is / m ² or less, when applied to the skin, it is possible to reduce the paleness peculiar to titanium oxide particles while having a hiding power and a transparent feeling. Therefore, it can be suitably used for base makeup cosmetics such as foundations. Further, since the titanium oxide powder of the present invention is excellent in performance as a white pigment, it can also be used for industrial applications such as white ink, and its industrial value is great.

X Maximum value of the line segment connecting two vertices facing each other Y Minimum value of the line segment connecting two vertices substantially orthogonal to the line segment related to the maximum value of the distance between the two vertices facing each other

Claims (6)

A titanium oxide powder having a BET specific surface area of 5 m ² / g or more and 15 m ^{2 / g or less.}
The titanium oxide powder contains octahedral particles and contains octahedral particles.
The content of the octahedral particles is 50% by number or more, and the content is 50% or more.
Generated on the surface of titanium oxide particles measured by putting 5 mL of 10 vol% triethanolamine aqueous solution and 50 mg of titanium oxide particles in a closed container with an inner diameter of 15 mm in a nitrogen atmosphere and irradiating them with ultraviolet light having a wavelength of 365 nm in a suspended state. Titanium oxide powder having a Ti ³⁺ density of 0.1 μmol / m ^{2 or less.} The oxidation according to claim 1, wherein the octahedral particles are octahedral titanium oxide particles having an average maximum value of a line segment connecting two facing vertices of 300 nm or more and 1000 nm or less. Titanium powder. The value obtained by dividing the average value of the maximum values by the average particle size converted from the BET specific surface area (average value of maximum values / average particle size converted to BET) is 0.5 or more and 2.5 or less. The titanium oxide powder according to claim 2. The titanium oxide powder according to any one of claims 1 to 3 , which has any of an inorganic compound and an organic compound on the surface. A dispersion liquid comprising the titanium oxide powder according to any one of claims 1 to 4 and a dispersion medium. A cosmetic comprising the titanium oxide powder according to any one of claims 1 to 4 and a cosmetic base.

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