JP2021011428A - Titanium oxide powder and method for producing the same, and dispersion liquid and cosmetic using the same - Google Patents

Abstract

To provide a titanium oxide powder for improving hiding power and spreadability when blended in a cosmetic and to provide a dispersion liquid and a cosmetic using the same.SOLUTION: There is provided a titanium oxide powder which contains polyhedral titanium oxide particles having a BET specific surface area of 5 m2/g or more and less than 15 m2/g and eight or more surfaces and has an average friction coefficient measured at 0.245 N per 1 cm2 of 0.5 or less.SELECTED DRAWING: Figure 1

Description

The present invention relates to titanium oxide powder and a method for producing the same, which are 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, submicron size to micron size titanium oxide particles are used in base makeup cosmetics such as foundations.
The titanium oxide particles having excellent hiding power include, for example, octahedral particles in which the average value of the maximum value of the line segment connecting two opposing vertices in one particle is 300 nm or more and 1000 nm or less, and the average of the maximum values is included. It is known that the value obtained by dividing the value by the average particle size converted from the BET specific surface area (average value of the maximum value / average particle size converted to BET) is 1.0 or more and 2.5 or less (for example). See Patent Document 1).

International Publication No. 2018/003851

However, in addition to the hiding power, there has been a demand for titanium oxide powder that can further improve the spread of cosmetics when applied to the skin.

The present invention has been made in view of the above circumstances, and is a titanium oxide powder that improves hiding power and elongation when blended in cosmetics, a method for producing the same, and a dispersion using the same. The purpose is to provide cosmetics.

That is, 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, contains polyhedral titanium oxide particles having eight or more faces, and contains 0.245 N per cm ² . The average friction coefficient measured in 1) is 0.5 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.

In the method for producing a titanium oxide powder of the present invention, a reaction solution is obtained by mixing a hydrolysis product of titanium alkoxide or a hydrolysis product of a titanium metal salt having a predetermined concentration and a compound having a five-membered ring containing nitrogen. The step of preparing the reaction solution and the step of hydrothermally synthesizing the reaction solution are provided, and the predetermined concentration is 0.4% by mass or more and 6.4% by mass or less in terms of the concentration of titanium oxide in the reaction solution. It is characterized by being.

According to the titanium oxide powder of the present invention, it is possible to provide a titanium oxide powder having excellent hiding power and elongation when blended with a cosmetic and applied to the skin, and a dispersion liquid and a cosmetic using the same.

According to the dispersion liquid of the present invention, when a cosmetic containing this dispersion liquid is applied to the skin, it is excellent in hiding power and elongation.

According to the cosmetic of the present invention, when applied to the skin, it has excellent hiding power and elongation.

According to the method for producing a titanium oxide powder of the present invention, it is possible to provide a titanium oxide powder having excellent hiding power and elongation when blended with a cosmetic and applied to the skin.

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 schematic diagram which shows the state before the average friction coefficient measurement. It is a schematic diagram which shows the state after the average friction coefficient measurement. It is a figure which shows the scanning electron microscope image which shows an example of the titanium oxide powder of Example 1. FIG.

The titanium oxide powder of the present invention, a method for producing the same, and embodiments of 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 has a BET specific surface area of 5 m ² / g or more and 15 m ² / g or less, contains polyhedral-shaped titanium oxide particles having eight or more faces, and is 0.245 N per cm ² . The measured average coefficient of friction is 0.5 or less.

(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, 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 hiding power and transparency. 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 short wavelengths increases as compared with the light scattering intensity of long wavelengths, and the paleness increases.

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.

(Titanium oxide particles)
The titanium oxide powder of this embodiment is an aggregate of titanium oxide particles.
The shape of the titanium oxide particles of the present embodiment includes a polyhedral shape having eight or more faces.
Since the shape of the titanium oxide particles has eight or more surfaces, light can be scattered over a wide range. Therefore, when a cosmetic containing titanium oxide powder is applied to the skin, the transparency and hiding power can be improved.

The content of polyhedral titanium oxide particles having eight or more faces in the titanium oxide powder is represented by the number% calculated by the method described later. That is, the content of the polyhedral-shaped titanium oxide particles having eight or more faces in the titanium oxide powder is preferably 50% by number or more, 60% by number or more, or 70% by number or more. There may be. The upper limit of the content of polyhedral titanium oxide particles having eight or more faces in the titanium oxide powder may be 70% by number, 80% by number, or 90% by number. , 100% by number.
When the content of polyhedron-shaped titanium oxide particles having eight or more faces in the titanium oxide powder is 50% by number or more, excellent hiding power is obtained when a cosmetic containing the titanium oxide powder is applied to the skin. It is preferable in that the paleness peculiar to the titanium oxide particles can be further reduced while having a transparent feeling.

The content of polyhedron-shaped titanium oxide particles having eight or more faces in the titanium oxide powder of the present embodiment, that is, the number%, is determined by, for example, a scanning electron microscope (SEM). It is a value calculated by observing 50 titanium oxide particles contained in the body and counting the number of polyhedron-shaped titanium oxide particles having eight or more faces contained in the 50 particles.

The maximum value of the line segment connecting the two vertices of the titanium oxide particles is not particularly limited as long as the BET specific surface area of the titanium oxide powder is 5 m ² / g or more and 15 m ² / g or less. For example, the maximum value is preferably 100 nm or more and 1000 nm or less, more preferably 150 nm or more and 800 nm or less, and further preferably 200 nm or more and 750 nm or less. The two vertices facing each other are not adjacent vertices. That is, in the two vertices, the line segment connecting the vertices is a line segment that does not pass through the surface of the particle but passes through the inside of the particle. The maximum value is obtained by the combination of the vertices farthest from each other.
The maximum value of the line segment connecting the two vertices facing each other means the maximum value of the length of the line segment connecting the two vertices facing each other.

A polyhedral shape having eight or more faces can be arbitrarily selected. A particle having a polyhedral shape is a particle having a plurality of faces. Examples of the polyhedral shape include octahedron, tetrahedron, dodecahedron, icositetrahedron, and star shape. Each face of the polyhedral shape may have substantially the same shape, or may include a plurality of faces having different shapes such as two types. The polyhedral shape may be a regular polyhedral shape or 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 in that light can be scattered over a wide range.
The polyhedral shape also includes a shape in which the corners of the polyhedron are rounded and the shape is rounded in whole or in part.
The polyhedral shape also includes a shape in which particles of the polyhedral shape are partially damaged. That is, when it has a shape similar to the polyhedral-shaped particles and it is presumed that this shape is formed from the polyhedral-shaped particles due to breakage, it is regarded as the polyhedral-shaped particles.
In addition, agglomerated particles in which polyhedral-shaped particles are agglomerated are also included.

Hereinafter, octahedral titanium oxide particles, which are a preferable example of the present embodiment, will be described in detail.

(Octahedron-shaped titanium oxide particles)
The octahedral shape described below is a three-dimensional shape in which the internal space is surrounded by eight triangles, as shown in FIG. The eight triangles may all have the same shape, or may include two or more different shapes, including two different shapes.
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 pointed shape, a rounded shape, and a flat shape. It may have a shaped shape. It also includes octahedrons with rounded corners, all or part of which are rounded. The octahedral titanium oxide particles also include a shape in which a part of the octahedral particles is damaged. That is, when it has a shape similar to the octahedral particles and it is presumed that this shape is formed from the octahedral particles due to breakage, it is regarded as the octahedral particles.
Further, the octahedral titanium oxide particles may be aggregated particles in which octahedral titanium oxide particles are aggregated with each other.

In the titanium oxide powder of the present embodiment, the content of octahedral titanium oxide particles (hereinafter, may be abbreviated as "octahedral particles") is preferably 50% by number or more. It may be 55% or more, or 60% or more.
In the titanium oxide powder of the present embodiment, the upper limit of the content of the octahedral particles may be 70% by number, 80% by number, 90% by number, 100. The number may be%.
When the content of octahedral particles in the titanium oxide powder is 50% by number or more, when a cosmetic containing the titanium oxide powder is applied to the skin, it has excellent hiding power and transparency. , It is advantageous in that the paleness peculiar to titanium oxide particles can be further reduced.

Regarding the content of octahedral particles in the titanium oxide powder of the present embodiment, for example, 50 titanium oxide particles contained in the titanium oxide powder are observed with a scanning electron microscope, and the eight are included in the 50 particles. It can be calculated by counting the number of planar particles.

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 pointed shape, a rounded shape, and a flat shape. It may have a shaped shape.

(A line segment connecting two vertices facing each other)
The maximum value of the line segment connecting the two opposite vertices of the octahedral particles (hereinafter sometimes referred to as "distance between vertices") is that the BET specific surface area of the titanium oxide powder is 5 m ² / g or more and 15 m. ^{As long as it is 2} / g or less, it is not particularly limited. For example, the maximum value is preferably 100 nm or more and 1000 nm or less, more preferably 150 nm or more and 800 nm or less, further preferably 200 nm or more and 700 nm or less, and more preferably 250 nm or more and 600 nm or less. Most preferred.

Octahedral particles having a maximum distance between two vertices facing each other of 100 nm or more and 1000 nm or less can scatter visible light in a wider range than spherical and spindle-shaped titanium oxide particles. Therefore, it is presumed that a cosmetic containing titanium oxide powder containing octahedral particles can reduce the paleness peculiar to titanium oxide particles while achieving both hiding power and transparency.
When the maximum value of the distance between two vertices facing each other of the octahedral particles is 100 nm or more and 1000 nm or less, when applied to the skin, the paleness peculiar to the titanium oxide particles is further enhanced while having an excellent transparency. It is advantageous in that it can be reduced.

The maximum value of the line segment (long axis m of the octahedral particle in FIG. 1) connecting the two opposing 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 (long 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 above ratio (X / Y) is 1.5 or more and 3.0 or less, the cosmetic containing titanium oxide powder containing octahedral particles has an octahedral shape when applied to the skin. It is advantageous in that the light scattering effect of the 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) need to 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 a square bottom surface. 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 particles 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 the 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. The distance between the two apex of the octahedral particle is the distance a between the point A and the point C, the distance b between the point A and the point D, the distance c between the point A and the point E, and the point A in FIG. 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 of the octahedral particle facing each other is the distance m, which corresponds to the maximum value (X) of the distance between the two vertices of the octahedral particle facing each other. 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 vertices facing each other of the octahedral particles and the minimum value (Y) (nm) of the distance between the two vertices facing each other of the octahedral particles are, for example, scanning type. It can be measured by observing octahedral particles using a scanning electron microscope (SEM).
If a part of the octahedral particles is damaged and the shape before the damage can be inferred, the shape of the octahedral particles before the damage is the above maximum value X (nm) and the above minimum value. (Y) nm is measured. When the octahedral particles are agglomerated with each other, the shape of one octahedral particle in the agglomerated particles is estimated, and the maximum value X (nm) and the minimum value (Y) nm are measured.

The above ratio (X / Y) is calculated by observing titanium oxide particles using a scanning electron microscope (SEM) and measuring the above maximum value (X) and the above minimum value (Y).

(Average coefficient of friction)
The titanium oxide powder of the present embodiment has an average coefficient of friction measured at 0.245 N per cm ² of 0.5 or less, preferably 0.4 or less, and more preferably 0.3 or less. .. The lower limit of the average coefficient of friction is 0, but it may be 0.1 or more.
Since the average friction coefficient is 0.5 or less, when the titanium oxide powder is blended in the cosmetic, a cosmetic having excellent elongation can be obtained.

The average friction coefficient of the titanium oxide powder of the present embodiment is a value measured by the following procedure using a friction feeling tester (model number: KES-SE, manufactured by Kato Tech Co., Ltd.).
FIG. 3 is a schematic view showing a state before measuring the average friction coefficient.
As shown in FIG. 3, the friction tester 100 measures the friction coefficient of the stage 200, the skin model substrate 300 arranged on the stage 200, and the titanium oxide powder 10 arranged on the skin model substrate 300. It includes a piano wire sensor 400 and a detection unit 500 that detects the friction coefficient measured by the piano wire sensor 400.
As shown in FIG. 3, on the stage 200, a skin model substrate (cheek skin model 30s (φ55 mm × 5 Tmm), manufactured by Bulux Co., Ltd.) on which 1 g of titanium oxide powder 10 was placed was placed on the titanium oxide powder. Place 10 so that it is below the 1 cm ² piano wire sensor (device standard) 400. Since all the titanium oxide powder 10 needs to be arranged under the piano wire sensor 400, the titanium oxide powder 10 is arranged on the skin model substrate 300 within a range of 1 cm ² . Next, the piano wire sensor 400 is brought into contact with the titanium oxide powder 10 so as to have a load of 25 g (25 × 10 ^-3 kg × 9.8 m / s ² = 0.245 N). Next, the average friction coefficient of the titanium oxide powder 10 can be measured by moving the skin model substrate 300 horizontally by 30 mm at a speed of 1 mm / s on the stage 200.
FIG. 4 is a schematic view showing a state after the skin model substrate on which the titanium oxide powder is placed is moved in the horizontal direction on the stage.

(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, and may be 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 color can be obtained.

The fact that the titanium oxide powder is 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, it can be seen that the titanium oxide powder is anatase type.

(Particle size distribution)
In the titanium oxide powder of the present embodiment, when the cumulative volume percentage of the particle size distribution of the polyhedral titanium oxide particles having eight or more faces is 10%, which is the maximum value of the line segment connecting the two vertices facing each other. The value (d10 / d50) obtained by dividing the maximum value (d10) by the maximum value (d50) when the cumulative volume percentage is 50% (hereinafter, may be abbreviated as “d10 / d50”). It 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 in the above range, a cosmetic having more excellent elongation can be obtained when blended in the cosmetic.

d10 and d50 are obtained by the following procedure. The maximum value of the distance between two vertices facing each other of a polyhedral particle having 50 or more faces is measured. The measured maximum value is cubed and multiplied by a constant to obtain a volume. The constant may be appropriately determined according to the shape of the titanium oxide particles. For example, the constant for a polyhedral shape having eight or more faces is 0.145, and the constant for a spherical shape is 4.19 (4π / 3). The volume particle size distribution of the maximum value is calculated by using the measured maximum value and the volume value obtained by calculation. d10 means the maximum value at the time of cumulative 10%, and d50 means the maximum value at the time of cumulative 50%.

The value (d50) of the maximum value of the line segment connecting the two facing vertices of the titanium oxide powder of the present embodiment when the cumulative volume percentage is 50% is preferably 100 nm or more and 1000 nm or less, preferably 150 nm. It is more preferably more than 800 nm and less, more preferably 200 nm or more and 700 nm or less, and most preferably 250 nm or more and 600 nm or less. In addition, d50 corresponds to the volume average particle diameter of the titanium oxide powder of this embodiment.

(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 an inorganic component and an organic component.

Examples of the inorganic component include inorganic oxides. For example, silica, alumina and the like can be mentioned.

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

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. One of these silicone compounds may be used alone, or two or more thereof may be used in combination.

Examples of fatty acids include palmitic acid, isostearic acid, stearic acid, lauric acid, myristic acid, behenic acid, oleic acid, loginic acid, 12-hydroxystearic acid, ricinoleic 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, isopropyldimethacrylic isostearoyl 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, it has excellent hiding power and elongation. Further, according to the titanium oxide powder of the present embodiment, when a cosmetic containing the titanium oxide powder is applied to the skin, it has excellent transparency in addition to hiding power, and has a paleness peculiar to titanium oxide particles. It is possible to obtain a natural finish with reduced.

[Manufacturing method of titanium oxide powder]
In the method for producing titanium oxide powder of the present embodiment, a hydrolysis product of titanium alkoxide or a hydrolysis product of a titanium metal salt having a predetermined concentration is mixed with a compound having a five-membered ring containing nitrogen and reacted. It has a step of preparing a solution (hereinafter referred to as "first step") and a step of hydrolyzing this reaction solution (hereinafter referred to as "second step").
Further, in the method for producing the titanium oxide powder of the present embodiment, if necessary, the reaction solution obtained in the first step and the reaction solution after hydrothermal synthesis obtained in the second step are mixed. It has a third step of hydrothermal synthesis.

(First step)
The first step is a step of preparing a reaction solution.
The first step is a step of preparing a reaction solution (slurry) by mixing a hydrolysis product of titanium alkoxide or a hydrolysis product of a titanium metal salt having a predetermined concentration and a compound having a five-membered ring containing nitrogen. is there.

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

Examples of the titanium alkoxide include tetraethoxytitanium, tetraisopropoxytitanium, tetranormalpropoxytitanium, tetranormalbutoxytitanium and the like. One of these titanium alkoxides may be used alone, or two or more thereof may be used in combination. 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 and titanium sulfate. One of these titanium metal salts may be used alone, or two or more thereof may be used in combination.

In the method for producing titanium oxide powder of the present 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 of titanium alkoxides or hydrolysis products of titanium metal salts 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 of titanium alkoxide or the hydrolysis product of titanium metal salt with pure water.
Examples of the method for cleaning the hydrolysis product of titanium alkoxide or the hydrolysis product of titanium metal salt include decantation, Nutche method, ultrafiltration method and the like.

(Compound with a five-membered ring containing nitrogen)
The nitrogen-containing five-membered ring compound is included in the reaction solution because of its function as a pH regulator for the reaction solution and as a catalyst for hydrothermal synthesis.
Examples of the nitrogen-containing compound having a five-membered ring include pyrrole, imidazole, indole, purine, pyrrolidine, pyrazole, triazole, tetrazole, isothiazole, isoxazole, furazan, carbazole, and 1,5-diazabicyclo- [4.3. .0] -5-Nonen and the like. These nitrogen-containing five-membered ring compounds 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 from the viewpoint that the particle size distribution of the titanium oxide powder can be narrowed and the crystallinity can be further improved. Preferably, for example, pyrrole, indole, pyrrolidine, isothiazole, isoxazole, frazan, carbazole, and 1,5-diazabicyclo- [4.3.0] -5-nonen are preferred.
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.

(Reaction solution)
The method for preparing the reaction solution is not particularly limited, and can be appropriately selected depending on the intended purpose. Examples of the method for preparing the reaction solution include a method of mixing using a stirrer, a bead mill, a ball mill, an attritor, a dissolver and the like.

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 according to the friction coefficient of the target titanium oxide powder, and is preferably 0.05 mol / L or more and 0.8 mol / L or less, and is 0. More preferably, it is 1 mol / L or more and 0.7 mol / L or less.
In other words, the concentration of titanium oxide in the reaction solution is preferably 0.4% by mass or more and 6.4% by mass or less, and 0.8% by mass or more and 5.6% by mass or less. Is more preferable. The concentration of titanium oxide in this reaction solution is the above-mentioned predetermined concentration. The titanium oxide content means the mass of titanium oxide produced from titanium alkoxide or titanium metal salt used as a raw material. For example, when 1 mol of tetraethoxytitanium is used, 1 mol of titanium oxide is produced, so that the titanium oxide content of 1 mol of tetraethoxytitanium is the amount of 1 mol of titanium oxide, that is, 80 g.

When the titanium atom concentration in the reaction solution is 0.05 mol / L or more, nuclei of titanium oxide particles having eight or more faces are efficiently generated, and the production efficiency is improved. When the titanium atom concentration in the reaction solution is 0.8 mol / L or less, the nucleation rate becomes slow, so that the content of small titanium oxide particles contained in the powder is reduced, and the average of the titanium oxide powder is reduced. The friction coefficient becomes smaller.
The titanium atom concentration in the reaction solution can be adjusted by controlling the content of the hydrolysis product of titanium alkoxide or the hydrolysis product of the titanium metal salt and the content of water.

When the concentration of titanium oxide in the reaction solution is 0.4% by mass or more, nuclei of titanium oxide particles having eight or more faces are generated, and the titanium oxide particles of the present embodiment can be produced. On the other hand, when the concentration of titanium oxide in the reaction solution is 6.4% by mass or less, the nucleation rate becomes slow, so that the content of small titanium oxide particles contained in the powder is reduced, and the titanium oxide powder is used. The average friction coefficient of the body becomes smaller.

The molar ratio of the titanium atom to the nitrogen-containing five-membered ring compound (titanium atom: nitrogen-containing five-membered ring compound) in the reaction solution is 1.0: 0.5 to 1.0: 5. It is preferably 0, more preferably 1.0: 0.6 to 1.0: 3.0, and even more preferably 1.0: 0.6 to 1.0: 1.5. ..
When the molar ratio of the titanium atom and the compound having a five-membered ring containing nitrogen in the reaction solution is within the above range, octahedral titanium oxide particles can be produced.

(Second step)
The second step is a step of producing titanium oxide particles.
The second step is a step of producing titanium oxide particles by hydrothermal synthesis of the reaction solution prepared in the first step.

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 pressure inside the container rises due to the evaporation of water in the reaction solution, so that a high-temperature and high-pressure reaction can be carried out.

The heating holding temperature in hydrothermal synthesis is preferably 150 ° C. or higher and 350 ° C. or lower, more preferably 150 ° C. or higher and 280 ° C. or lower, and further preferably 150 ° C. or higher and 210 ° C. or lower.
When the heating holding temperature in hydrothermal synthesis is within the above range, the solubility of the hydrolysis product of titanium alkoxide or the hydrolysis product of the titanium metal salt in water is improved, and it can be dissolved in the reaction solution. it can. In addition, the nuclei of titanium oxide particles can be generated, the nuclei 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 vessel.

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 holding 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 more, and preferably 4 hours or more. More preferred.
If the heating and holding time is less than 3 hours, the hydrolysis product of titanium alkoxide or the hydrolysis product of titanium metal salt, which is a raw material, may not react and the yield may decrease.

The heating 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 titanium oxide particles may be heated and held for a desired size. For example, the heating 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.

(Third step)
The third step is a step of crystal growing the titanium oxide particles obtained in the second step. The third step is performed when the size of the obtained titanium oxide particles is smaller than desired.
The third step is a reaction solution containing titanium oxide particles after hydrothermal synthesis obtained in the second step and a reaction solution (hydrolysis product of titanium alkoxide or titanium metal) prepared in the first step before hydrothermal synthesis. This is a step of mixing a hydrolyzed product of a salt and a compound having a five-membered ring containing nitrogen) for hydrothermal synthesis. Mixing the reaction solution prepared in the first step before hydrothermal synthesis means hydrolyzing the hydrolysis product of titanium alkoxide or the hydrolysis product of titanium metal salt and a compound having a 5-membered ring containing nitrogen. It may be a method of adding each to the reaction solution containing titanium oxide particles later.

A reaction solution containing titanium oxide particles after hydrothermal synthesis obtained in the second step, a reaction solution prepared in the first step (a hydrolysis product of titanium alkoxide or a hydrolysis product of a titanium metal salt, and nitrogen) are used. The mixing ratio with the compound having a five-membered ring containing the titanium oxide is preferably 1: 1 to 1:20 in terms of mass of titanium oxide particles. The mixing ratio may be 1: 1 to 1: 5, 1: 5 to 1:10, 1: 10 to 1:20, or the like, if necessary.

The hydrothermal synthesis in the third step can be carried out under the same conditions as in the second step.

The method for extracting the titanium oxide particles from the reaction solution after performing the second step and the third step is not particularly limited, and can be appropriately selected depending on the intended purpose. Examples of the method for extracting the titanium oxide particles from the reaction solution include a method of solid-liquid separation such as decantation and the Nutche method.

After taking out the solid matter containing the titanium oxide particles, the obtained solid matter containing the titanium oxide particles may be washed with pure water or the like for the purpose of reducing impurities.
The solid matter containing the titanium oxide particles taken out by solid-liquid separation may be naturally dried, or may be heated and dried at a drying temperature higher than room temperature, for example, 400 ° C. or lower.
The lower limit of the heating temperature of the solid matter containing the titanium oxide particles is not particularly limited as long as the solid matter containing the titanium oxide particles can be dried. The lower limit of the heating temperature of the solid matter containing the titanium oxide particles may be, for example, 200 ° C., 250 ° C., or 300 ° C.
By drying the solid matter containing the titanium oxide particles 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 deteriorates, which is not preferable.
The titanium oxide powder of the present embodiment can be obtained by taking out the titanium oxide particles from the reaction solution after hydrothermal synthesis and drying them.

(surface treatment)
The titanium oxide particles can also be surface-treated. The time for surface treatment is not particularly limited, and can be appropriately selected depending on the purpose. Examples of the time for performing the surface treatment include after the second step and after the third 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 used.

According to the method for producing titanium oxide powder of the present embodiment, when a cosmetic containing titanium oxide powder is applied to the skin, titanium oxide powder having excellent hiding power and elongation can be obtained. Further, according to the method for producing titanium oxide powder of the present embodiment, when a cosmetic containing titanium oxide powder is applied to the skin, it has excellent transparency in addition to hiding power, and is peculiar to titanium oxide particles. Titanium oxide powder can be obtained that can obtain a natural finish with reduced paleness.

[Dispersion]
The dispersion liquid of the present embodiment contains the titanium oxide powder of the present embodiment and the dispersion medium. The dispersion of the present embodiment contains other components as needed.
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 with 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 polysiloxanes, hydrocarbon oils, ester oils, higher fatty acids, and higher alcohols. And so on. 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 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 polysiloxanes include chain polysiloxanes such as dimethylpolysiloxane, methylphenylpolysiloxane, and diphenylpolysiloxane; cyclic polysiloxanes such as octamethylcyclotetrasiloxane, decamethylcyclopentasiloxane, and dodecamethylcyclohexasiloxane. Kind and the like.

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, hexyldodecanol, isostearyl alcohol and the like.

(Other ingredients)
The other components are not particularly limited as long as the effects of the dispersion liquid of the present embodiment are not impaired, 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. One of these components may be used alone, or two or more thereof may be used in combination.

The content of the dispersion medium in the dispersion 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, based on the total amount of the dispersion liquid of the present embodiment. It is more preferably more than mass% 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, it is excellent in hiding power and elongation. Further, according to the dispersion liquid of the present embodiment, when a cosmetic containing titanium oxide powder is applied to the skin, it has excellent transparency in addition to hiding power and elongation, and has a paleness peculiar to titanium oxide particles. It is possible to obtain a natural finish with reduced.

[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 dispersion device 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 has excellent elongation, and can reduce the paleness peculiar to titanium oxide while achieving both hiding power and transparency.

[Cosmetics]
The cosmetic of the present embodiment contains the titanium oxide powder of the present embodiment and a cosmetic base. Further, the cosmetics of another embodiment include a dispersion liquid containing titanium oxide 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 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 cosmetics is not particularly limited and can be appropriately selected depending on the intended purpose.

(Other ingredients)
In addition to the titanium oxide powder of the present embodiment and the cosmetic base, the cosmetic of the present embodiment may contain other components 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. One of these components may be used alone, or two or more thereof may be used in combination.
The content of other ingredients 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 the cosmetics of the present embodiment is, for example, a method of mixing titanium oxide powder with a cosmetic base and mixing other components for production, or mixing titanium oxide powder with existing cosmetics. Examples include a method of manufacturing, a method of mixing a dispersion containing titanium oxide with a cosmetic base and mixing other components, and a method of mixing a dispersion containing titanium oxide with an existing cosmetic. Be done.

(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 dispersed form of the gel-like cosmetics include a water-in-oil (W / O type) emulsion, an oil-in-water type (O / W type) emulsion, and an oil type.

Examples of the cosmetics of the present embodiment include base make-up, manicure, lipstick and the like. Of 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 has excellent elongation and hiding power. Further, according to the cosmetic of the present embodiment, it is possible to reduce the paleness peculiar to titanium oxide particles while having a transparent feeling.

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)
5 L of pure water is placed in a glass container, and 5 mol of tetraisopropoxytitanium (trade name: A-1, manufactured by Nippon Soda Co., Ltd.) is added dropwise with stirring to obtain a white suspension which is a hydrolysis product of titanium alkoxide. It was.
The white suspension was then filtered to give white cake A, a solid portion of the hydrolysis product of titanium alkoxide.
Next, a slurry (B1) was prepared by adding 5 mol (400 g) of white cake (A) in terms of titanium oxide, 7 mol of pyrrolidine (manufactured by Kanto Chemical Co., Inc.), and pure water to an autoclave to make a total of 10 kg. .. The concentration of titanium oxide in the slurry (B1) was 4% by mass.
Next, the slurry (B1) was held at 260 ° C. for 6 hours using an autoclave to obtain a titanium oxide particle suspension (C1).

Next, the titanium oxide particle suspension (C1) was added to 4500 g (titanium oxide content 180 g), and the white cake (A) obtained in the same manner as above was added to 4.5 mol (titanium oxide content 360 g). , Pyrrolidine was added to 6.5 mol and pure water was added to bring the total amount to 10 kg, and the slurry (D1) was adjusted. The concentration of titanium oxide in the slurry (D1) was 5.4% by mass.
Next, the slurry (D1) was held at 250 ° C. for 6 hours using an autoclave to obtain a titanium oxide particle suspension (E1).
The titanium oxide particle suspension (E1) was separated into solid and liquid, and the solid was dried at 200 ° C. to obtain the titanium oxide powder of Example 1.

(Evaluation of 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 9 m ² / g. The results are shown in Table 1.

"Content rate of octahedral particles"
As a result of observing 50 titanium oxide particles with a scanning electron microscope (SEM) (trade name: S-4800, manufactured by Hitachi High-Technologies Corporation), 60 octahedral titanium oxide particles were found in the titanium oxide powder. %Were present. The results are shown in Table 1.
In addition, it was also confirmed by the transmission electron microscope that the titanium oxide powder of Example 1 contained octahedral titanium oxide particles.

(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). As a result, the titanium oxide powder of Example 1 was anatase single phase. The results are shown in Table 1.

(Evaluation of average coefficient of friction)
1 g of titanium oxide powder of Example 1 was placed on a skin model substrate (cheek skin model 30s (φ55 mm × 5 Tmm), manufactured by Burax).
Next, a skin model substrate on which 1 g of titanium oxide powder was placed was placed under a 1 cm ² piano wire sensor (device standard) of a friction tester (model number: KES-SE, manufactured by Kato Tech Co., Ltd.).
Next, the average coefficient of friction was measured by moving the substrate by 30 mm in the horizontal direction at a speed of 1 mm / s with the sensor in contact with the titanium oxide powder so as to have a load of 25 g (0.245 N). .. As a result, the average coefficient of friction was 0.21. The results are shown in Table 1.

(Evaluation of maximum value (X) and minimum value (Y))
In FIG. 2, a 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 powder of Example 1 was prepared using a scanning electron microscope (SEM) (trade name: JSM-7200F, manufactured by Nippon Denshi Co., Ltd.). It was measured by observing the secondary electron image. The SEM image is shown in FIG. Table 1 shows the maximum value (X) / minimum value (Y).

(Evaluation of particle size distribution)
The maximum value (X) of the 50 particles obtained above was each cubed and multiplied by a constant of 0.145 to calculate the volume. The volume particle size distribution was calculated using the maximum value (X) and the volume value. The maximum value (X) (d10) when the cumulative volume percentage was 10%, the maximum value (X) (d50) when the cumulative volume percentage was 50%, and d10 / d50 were calculated. The results are shown in Table 1.

(Makeup of cosmetics)
2 g of titanium oxide powder of Example 1 and 8 g of talc were mixed in a mortar to prepare a base make-up cosmetic of Example 1.

[Comparative Example 1]
(Preparation of titanium oxide powder)
The white cake (A) obtained in the production process of Example 1 was added with 1 mol (80 g) of titanium oxide, 0.7 mol of pyrrolidine, and pure water to make a total amount of 1 kg, and the slurry (B2) was prepared. The concentration of titanium oxide in the slurry (B2) was 8% by mass.
Next, the slurry (B2) was held at 220 ° C. for 9 hours using an autoclave to obtain a titanium oxide particle suspension (C2).
Next, 100 g of titanium oxide particle suspension (C2) (8 g of titanium oxide content), 1 mol of white cake (A) with titanium oxide content (80 g of titanium oxide content), 0.7 mol of pyrrolidine, and pure water were added. In addition, the slurry (D2) was adjusted so that the total amount was 1 kg. The concentration of titanium oxide in the slurry (D2) was 8.8% by mass.
Next, the slurry (D2) was held at 220 ° C. for 9 hours using an autoclave to obtain a titanium oxide particle suspension (E2).
The obtained titanium oxide particle suspension (E2) was separated into solid and liquid, and the solid was dried at 200 ° C. to obtain the titanium oxide powder of Comparative Example 1.

(Evaluation of titanium oxide powder)
Table 1 shows the evaluation results in the same manner as in Example 1.

(Makeup of cosmetics)
The base make-up cosmetic of Comparative Example 1 was prepared in the same manner as in Example 1.

(Evaluation of growth)
The cosmetics of Example 1 and Comparative Example 1 were applied to the skin, respectively, and 10 people evaluated which cosmetic had the best growth. As a result, all 10 people evaluated that the cosmetics of Example 1 had better growth than Comparative Example 1.

By comparing Example 1 and Comparative Example 1, it was confirmed that the base make-up cosmetic containing titanium oxide powder having a small average friction coefficient spreads well when applied to the skin.

The titanium oxide powder of the present invention contains polyhedral titanium oxide particles having a BET specific surface area of 5 m ² / g or more, 15 m ² / g or less, and eight or more faces, and was measured at 0.245 N per cm ² . Since the average coefficient of friction is 0.5 or less, it has excellent elongation and hiding power when applied to the skin. Therefore, the titanium oxide powder of the present invention 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 be used for industrial applications such as white ink, and its industrial value is great.

10 Titanium oxide powder 100 Friction tester 200 Stage 300 Skin model substrate 400 Piano wire sensor 500 Detection unit X Maximum value of line segment connecting two vertices facing each other Y Line segment related to maximum value of distance between two vertices facing each other The minimum value of the line segment connecting two vertices that is approximately orthogonal to

Claims (7)

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 polyhedral-shaped titanium oxide particles having eight or more faces.
A titanium oxide powder characterized by having an average coefficient of friction of 0.5 or less measured at 0.245 N per cm ² . The maximum value (d10) of the maximum value of the line segment connecting the two vertices of the titanium oxide particles when the cumulative volume percentage of the particle size distribution is 10%, and the above when the cumulative volume percentage is 50%. The titanium oxide powder according to claim 1, wherein the value (d10 / d50) divided by the maximum value (d50) is 0.3 or more and 1 or less. The titanium oxide powder according to claim 1 or 2, wherein the content of the polyhedral-shaped titanium oxide particles in the titanium oxide powder is 50% by number or more. The titanium oxide powder according to any one of claims 1 to 3, which has either an inorganic compound or an organic compound on the surface. A dispersion liquid containing 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. A step of preparing a reaction solution by mixing a hydrolysis product of titanium alkoxide or a hydrolysis product of a titanium metal salt having a predetermined concentration with a compound having a five-membered ring containing nitrogen.
It has a step of hydrothermally synthesizing the reaction solution.
The invention according to any one of claims 1 to 4, wherein the predetermined concentration is 0.4% by mass or more and 6.4% by mass or less in terms of the concentration of titanium oxide in the reaction solution. Method for producing titanium oxide powder.