JP2018111689A - Ultraviolet-shielding particle coated with silicon oxide, aqueous composition containing ultraviolet-shielding particle coated with silicon oxide, and cosmetic - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ultraviolet-shielding particle coated with silicon oxide that can exhibit desired ultraviolet-shielding properties even when applied to an aqueous cosmetic, an aqueous composition containing an ultraviolet-shielding particle coated with silicon oxide and a cosmetic containing the same.SOLUTION: Provided is an ultraviolet-shielding particle coated with silicon oxide, in which the surface of an ultraviolet-shielding particle is coated with a silicon oxide film, wherein, a composition, which comprises: 46.0 pts.mass of a gel obtained by mixing water and an alkyl-modified carboxyvinyl polymer 0.2 pts.mass and adjusting the pH to 6.0 with 2.5 mol/L sodium hydroxide; the ultraviolet-shielding particle coated with silicon oxide 50 pts.mass; and glycerol 4.0 pts.mass, is mixed with decamethylcyclopentasiloxane at a mass ratio of 1: 1, and it is dispersed for 10 minutes by ultrasonic, to obtain a liquid mixture. After the liquid mixture is allowed to stand for 20 hours, an oil phase of the liquid mixture has 360 nm transmittance of 100%. And, when the composition 10 pts.mass and carboxyvinyl polymer gel 90 pts.mass are mixed and the mixture is held between slide glasses for observation by light microscopy, the aggregate observed has a particle size of 50 μm or less.SELECTED DRAWING: None

Description

  The present invention relates to silicon oxide-coated ultraviolet shielding particles, an aqueous composition containing silicon oxide-coated ultraviolet shielding particles, and a cosmetic.

  Cosmetics containing ultraviolet shielding particles are frequently used not only for leisure purposes but also on a daily basis. Therefore, in cosmetics, a feeling that does not feel stress is emphasized so that it can be used every day. In order to obtain such a feel, cosmetics are required to be water-based with a fresh feeling of use.

  Since water-based cosmetics are less sticky than oil-based cosmetics and provide a fresh feeling of use, in recent years, various oil-in-water (O / W) cosmetics such as sunscreens, emulsions, and creams are used. It is used as

  As ultraviolet shielding particles that can be used in such water-based cosmetics, zinc oxide particles coated with silicon oxide are known (see, for example, Patent Documents 1 and 2).

International Publication No. 2014/171322 International Publication No. 2015/072499

  However, when a water-based cosmetic is prepared using the silicon oxide-coated zinc oxide described in Patent Document 1 or Patent Document 2, the silicon oxide-coated zinc oxide can be mixed in the water-based cosmetic. However, when it was used as a coating film, there was a problem that desired ultraviolet shielding properties could not be obtained.

  The present invention has been made in view of the above circumstances, and is applied to water-based cosmetics. Silicon oxide-coated ultraviolet shielding particles and a silicon oxide-coated ultraviolet shielding particle-containing aqueous system that can obtain desired ultraviolet shielding properties even when applied to water-based cosmetics. An object is to provide a composition and a cosmetic containing the composition.

  As a result of intensive studies to solve the above-mentioned problems, the inventors of the present invention, when the surface state of the silicon oxide-coated ultraviolet shielding particles is not familiar with decamethylpentasiloxane and mixed with a carboxyvinyl polymer, By controlling so that the silicon oxide-coated ultraviolet shielding particles do not aggregate with each other, it is found that silicon oxide-coated ultraviolet shielding particles capable of obtaining desired ultraviolet shielding properties when obtained as a coating film are obtained, and the present invention is completed. It came to.

  That is, the silicon oxide-coated ultraviolet shielding particle of the present invention is a silicon oxide-coated ultraviolet shielding particle in which the surface of the ultraviolet shielding particle is coated with a silicon oxide film, and water and 0.2 parts by mass of an alkyl-modified carboxyvinyl polymer are mixed. A composition comprising 46.0 parts by mass of gel adjusted to pH 6.0 with 2.5 mol / L sodium hydroxide, 50 parts by mass of the silicon oxide-coated ultraviolet shielding particles and 4.0 parts by mass of glycerin, After mixing a mixture of methylcyclopentasiloxane at a mass ratio of 1: 1 and dispersing for 10 minutes with ultrasonic waves, the mixture was allowed to stand for 20 hours, and then the transmittance of the oil phase of the mixture was 360 nm. 100%, 10 parts by weight of the composition, and carboxyvinyl polymer gel (pH 7.5 aqueous solution containing 1.5% by weight of carboxyvinyl polymer) And 0 parts by mass of, across the mixture to a glass slide, when observed with an optical microscope, the particle size of the aggregates to be observed, characterized in that at 50μm or less.

  The aqueous composition containing the silicon oxide-coated ultraviolet shielding particles of the present invention contains the silicon oxide-coated ultraviolet shielding particles of the present invention and water.

  The cosmetic of the present invention contains at least one of the silicon oxide-coated ultraviolet shielding particles of the present invention and the aqueous composition containing the silicon oxide-coated ultraviolet shielding particles of the present invention, and a cosmetic base material.

  The oil-in-water cosmetic of the present invention comprises at least one of the silicon oxide-coated ultraviolet shielding particles of the present invention and the aqueous composition containing the silicon oxide-coated ultraviolet radiation shielding particles of the present invention in an aqueous phase. To do.

  The silicon oxide-coated ultraviolet shielding particles of the present invention are excellent in ultraviolet shielding properties even when applied to water-based cosmetics.

  According to the silicon oxide-coated ultraviolet shielding particle-containing aqueous composition of the present invention, since it contains the silicon oxide-coated ultraviolet shielding particle of the present invention, it is excellent in ultraviolet shielding properties even when applied to aqueous cosmetics.

  According to the cosmetic of the present invention, since it contains at least one of the silicon oxide-coated ultraviolet shielding particles of the present invention and the silicon oxide-coated ultraviolet shielding particle-containing aqueous composition of the present invention, it has excellent ultraviolet shielding properties.

  According to the oil-in-water cosmetic of the present invention, it contains at least one of the silicon oxide-coated ultraviolet shielding particles of the present invention and the aqueous composition containing the silicon oxide-coated ultraviolet shielding particles of the present invention. Excellent.

1 is a diagram showing an optical microscopic image of an aqueous composition containing silicon oxide-coated zinc oxide particles of Example 1. FIG. It is a graph which shows the spectral transmittance | permeability of the silicon oxide covering zinc oxide particle containing aqueous composition of Example 1, Example 2, and Comparative Example 1 and Comparative Example 2. It is a figure which shows the time-dependent change of the viscosity in 40 degreeC of the silicon oxide covering zinc oxide particle containing aqueous composition of Example 1 and Example 2. FIG. 4 is a diagram showing an optical microscope image of the aqueous composition containing silicon oxide-coated zinc oxide particles of Example 2. FIG. It is a figure which shows the optical microscope image of the silicon oxide covering zinc oxide particle containing aqueous composition of the comparative example 1. It is a figure which shows the optical microscope image of the silicon oxide covering zinc oxide particle containing aqueous composition of the comparative example 2. 2 is a diagram showing an optical microscope image of the oil-in-water cosmetic of Example 1. FIG.

Preferred embodiments for carrying out the silicon oxide-coated ultraviolet shielding particles, the silicon oxide-coated ultraviolet shielding particle-containing aqueous composition, the cosmetics containing the same, and the oil-in-water cosmetics of the present invention will be described.
The following embodiments are specifically described for better understanding of the gist of the invention, and do not limit the present invention unless otherwise specified.

[Silicon oxide coated UV shielding particles]
The silicon oxide-coated ultraviolet shielding particles of this embodiment are silicon oxide-coated ultraviolet shielding particles in which the surface of the ultraviolet shielding particles is coated with a silicon oxide film, and water and an alkyl-modified carboxyvinyl polymer 0.2 parts by mass are mixed. A composition comprising 46.0 parts by mass of gel adjusted to pH 6.0 with 2.5 mol / L sodium hydroxide, 50 parts by mass of the silicon oxide-coated ultraviolet shielding particles and 4.0 parts by mass of glycerin, and decamethyl The mixture prepared by mixing with cyclopentasiloxane at a mass ratio of 1: 1 and dispersed by ultrasonic waves for 10 minutes was allowed to stand for 20 hours, and then the transmittance of the oil phase of the mixture was 360 nm. 10 parts by weight of the composition and 90 parts by weight of carboxyvinyl polymer gel (pH 7.5 aqueous solution containing 1.5% by weight of carboxyvinyl polymer) It was mixed, sandwiching the mixture to a glass slide, when observed with an optical microscope, the particle size of the agglomerates observed is 50μm or less.

  There is no particular limitation on the method for bringing the surface of the silicon oxide-coated ultraviolet shielding particles into a state in which aggregation of the particles is suppressed even if it is mixed with carboxyvinyl polymer without being familiar with decamethylpentasiloxane. For example, at least one functional group selected from the group consisting of an alkyl group, an alkenyl group and a cycloalkyl group is provided on the surface of the silicon oxide film, and these functional groups are 0.0001 mass in the silicon oxide-coated ultraviolet shielding particles. % And 0.20% by mass or less is adjusted.

  The at least one functional group selected from the group consisting of an alkyl group, an alkenyl group and a cycloalkyl group is not particularly limited as long as the compatibility with the oil component can be improved.

The alkyl group preferably has 1 or more and 8 or less carbon atoms, more preferably 1 or more and 6 or less, still more preferably 1 or more and 4 or less. Most preferred is 2 or more.
A group consisting of an alkyl group, an alkenyl group, and a cycloalkyl group on the surface of the silicon oxide film without excessively impairing the hydrophilicity of the silicon oxide film because the number of carbon atoms of the alkyl group is 1 or more and 8 or less. Excessive presence of at least one functional group selected from can be suppressed. Therefore, when the silicon oxide-coated ultraviolet shielding particles of this embodiment are used in water-based cosmetics or oil-in-water cosmetics, desired ultraviolet shielding properties can be obtained.

In the silicon oxide-coated ultraviolet shielding particles of the present embodiment, the content of at least one selected from the group consisting of an alkyl group, an alkenyl group and a cycloalkyl group with respect to the total amount (100% by mass) is 0.0001% by mass. It is preferably not less than 0.20% by mass, more preferably not less than 0.001% and not more than 0.15% by mass, and not less than 0.01% and not more than 0.10% by mass Is more preferable. When two or more types of functional groups are contained, the total content of these functional groups is preferably within the above range.
When the content of at least one functional group selected from the group consisting of an alkyl group, an alkenyl group and a cycloalkyl group is in the above range, the hydrophilicity of the silicon oxide film is not excessively impaired, and the silicon oxide Excessive presence of at least one functional group selected from the group consisting of an alkyl group, an alkenyl group, and a cycloalkyl group on the surface of the coating can be suppressed. Therefore, when the silicon oxide-coated ultraviolet shielding particles of this embodiment are used in water-based cosmetics or oil-in-water cosmetics, desired ultraviolet shielding properties can be obtained.

In the silicon oxide-coated ultraviolet shielding particles of the present embodiment, the content of the ultraviolet shielding particles with respect to the total amount (100% by mass) is preferably 50% by mass or more and 95% by mass or less, and 60% by mass or more and 90% by mass. More preferably, it is 70 mass% or less and more preferably 80 mass% or less.
When the content of the ultraviolet shielding particles is within the above range, a desired ultraviolet shielding property can be obtained when the silicon oxide-coated ultraviolet shielding particles of the present embodiment are used in water-based cosmetics or oil-in-water cosmetics. It is done. Further, the silicon oxide-coated ultraviolet shielding particles of the present embodiment can be mixed with water-based cosmetics or oil-in-water cosmetics.

  In the silicon oxide-coated ultraviolet shielding particles of the present embodiment, the content of silicon oxide is preferably 3% by mass or more and 45% by mass or less, and preferably 10% by mass or more and 40% by mass with respect to the total amount (100% by mass). % Or less, more preferably 15% by mass or more and 35% by mass or less. In view of suppressing elution of metal ions in the ultraviolet shielding particles, the content of silicon oxide is preferably 15% by mass or more. From the viewpoint of obtaining desired ultraviolet shielding properties, the silicon oxide content is preferably 30% by mass or less. When the average primary particle diameter of the ultraviolet shielding particles is 50 nm or less, the content of silicon oxide is preferably 3% by mass or more and 45% by mass or less. Moreover, when the average primary particle diameter of the ultraviolet shielding particles exceeds 50 nm, the content of silicon oxide is preferably 1% by mass or more and 35% by mass or less.

  The ultraviolet shielding particles are not particularly limited as long as they are metal oxide particles capable of shielding ultraviolet rays. Examples of such ultraviolet shielding particles include at least one selected from the group consisting of zinc oxide particles, titanium oxide particles, and cerium oxide particles. Among these, zinc oxide particles and titanium oxide particles are preferable because they are widely used as ultraviolet shielding particles for cosmetics.

In the silicon oxide-coated ultraviolet shielding particle of the present embodiment, when the presence ratio in Q ³ environments of silicon oxide, silicon in the film Q ^3, the abundance ratio of Q ⁴ environment of silicon oxide, silicon in the coating film was Q ^4, It is preferable that Q ³ + Q ⁴ ≧ 0.6 and Q ⁴ / (Q ³ + Q ⁴ ) ≧ 0.5. Further, it is preferable that the entire ultraviolet shielding particles are uniformly coated with the silicon oxide film so that the decomposition rate of brilliant blue generated by the photocatalytic activity of the silicon oxide-coated ultraviolet shielding particles is 3% or less. The decomposition rate of brilliant blue generated by the photocatalytic activity of the silicon oxide-coated ultraviolet shielding particles is more preferably 2% or less, and further preferably 1% or less.

The silicon oxide film is, "when Q ³ of the presence ratio in Q ³ environments of silicon oxide, silicon in the ^coating, the presence ratio in Q ⁴ environment of silicon oxide, silicon in the coating film was ^{Q 4, Q 3 + Q 4} ≧ 0. 6 and Q ⁴ / (Q ³ + Q ⁴ ) ≧ 0.5 ”as long as the degree of condensation is high.
There is a close relationship between the “denseness” of the dense silicon oxide film and the “condensation degree” of the silicon oxide, and the higher the degree of condensation of the silicon oxide, the higher the density of the silicon oxide film. It becomes.
In other words, the “dense” of the dense silicon oxide film referred to here means that the degree of condensation of silicon oxide is such that Q ³ + Q ⁴ ≧ 0.6 and Q ⁴ / (Q ³ + Q ⁴ ) ≧ 0.5. It means a silicon oxide film in a high state.
Since the silicon oxide film is dense, it is possible to suppress the elution of metal ions in the ultraviolet shielding particles from the silicon oxide-coated ultraviolet shielding particles of the present embodiment.

Regarding the degree of condensation of silicon oxide, the NMR spectrum of the silicon oxide-coated ultraviolet shielding particles was measured by solid ²⁹ Si MAS-nuclear magnetic resonance (NMR) spectroscopy, and Q ⁰ , Q ¹ , It can be easily known by measuring the area ratio of signals attributed to each environment of Q ² , Q ³ , and Q ⁴ .
Here, Q ⁿ (n = 0 to 4) is a cross-linked oxygen atom among the oxygen atoms of the SiO ₄ tetrahedron unit that is a structural unit of silicon oxide, that is, an oxygen atom bonded to two Si atoms. It is a chemical structure that depends on the number.
These ^{Q 0, Q 1, Q 2} , Q 3, Q 4 area ratio of the signal to be attributed to each ^environment, referred to as ^{Q 0, Q 1, Q 2} , Q 3, Q 4. However, Q ⁰ + Q ¹ + Q ² + Q ³ + Q ⁴ = 1.

  The reason why the brilliant blue decomposition rate generated by the photocatalytic activity of the ultraviolet shielding particles is preferably 3% or less will be described below. The reason is that if the decomposition rate of this brilliant blue is 3% or less, the photocatalytic activity of the ultraviolet shielding particles is suppressed, so that the uniformity of the silicon oxide film covering the ultraviolet shielding particles is also high. Because it means. Here, the high homogeneity of the silicon oxide film covering the ultraviolet shielding particles means that there is no coating unevenness, the coating is not localized, and there are no pinholes. The degradation rate of brilliant blue is used as an index of the photocatalytic activity of the ultraviolet shielding particles. The photocatalytic reaction of the ultraviolet shielding particles basically occurs on the surface of the ultraviolet shielding particles. That is, the low decomposition rate of brilliant blue generated by the photocatalytic activity of the ultraviolet shielding particles indicates that there are few portions where the ultraviolet shielding particles are exposed on the surface of the silicon oxide-coated ultraviolet shielding particles.

The method for measuring the degradation rate of brilliant blue is as follows.
First, a brilliant blue aqueous solution having a predetermined content (for example, 5 ppm) of brilliant blue is prepared, a predetermined amount is collected from the brilliant blue aqueous solution into a screw tube, and the collected brilliant blue aqueous solution is converted into ultraviolet shielding particles in terms of ultraviolet shielding particles. Silicon oxide-coated ultraviolet shielding particles having a mass of 1% by mass of the aqueous solution are added and ultrasonically dispersed to prepare a suspension.
Next, the suspension is irradiated with ultraviolet rays having a predetermined wavelength from a predetermined distance (for example, 10 cm) for a predetermined time (for example, 6 hours) using an ultraviolet irradiation lamp.
As the ultraviolet irradiation lamp, for example, a sterilization lamp GL20 (wavelength 253.7 nm, ultraviolet output 7.5 W: manufactured by Toshiba Corporation) can be used.

Next, a supernatant is collected from the suspension irradiated with the ultraviolet rays, and the absorbance spectra of the brilliant blue aqueous solution and the supernatant are measured by an atomic absorption spectrophotometry.
And using these measured values, the decomposition rate D of brilliant blue is calculated by the following formula (1).
D = (A0−A1) / A0 (1)
(However, A0 is the absorbance at the absorption maximum wavelength (630 nm) of the absorbance spectrum of the brilliant blue aqueous solution (5 ppm), and A1 is the absorbance at the absorption maximum wavelength of the absorbance spectrum of the supernatant.)

  In addition, about the normal zinc oxide particle (average particle diameter 35nm; Sumitomo Osaka Cement Co., Ltd. product) as an ultraviolet-shielding particle, it was 90% as a result of measuring the decomposition rate of brilliant blue based on said method. Accordingly, it was confirmed that the zinc oxide particles (average particle size 35 nm; manufactured by Sumitomo Osaka Cement Co., Ltd.) have a high decomposition rate of brilliant blue when having photocatalytic activity.

  The average primary particle diameter of the silicon oxide-coated ultraviolet shielding particles is preferably 1 nm or more and 2 μm or less, and is appropriately adjusted within the above range in order to obtain desired transparency and ultraviolet shielding properties. When it is desired to improve the transparency when applying cosmetics such as sunscreens containing the silicon oxide-coated ultraviolet shielding particles of the present embodiment, the average primary particle size of the silicon oxide-coated ultraviolet shielding particles is 1 nm or more and It is preferable that it is 50 nm or less. On the other hand, when it is desired to improve the ultraviolet shielding property, the average primary particle diameter of the silicon oxide-coated ultraviolet shielding particles is preferably 50 nm or more and 2 μm or less.

The “average primary particle diameter” in the silicon oxide-coated ultraviolet shielding particles of this embodiment is a numerical value obtained by the following method. That is, when the silicon oxide-coated ultraviolet shielding particles of this embodiment are observed using a transmission electron microscope (TEM) or the like, a predetermined number of, for example, 200 or 100 silicon oxide-coated ultraviolet shielding particles is selected. . Then, the longest linear portion (maximum major axis) of each of these silicon oxide-coated ultraviolet shielding particles is measured, and these measured values are weighted averaged.
When the silicon oxide-coated ultraviolet shielding particles are aggregated, the aggregated particle diameter of the aggregate is not measured. A predetermined number of silicon oxide-coated ultraviolet shielding particles (primary particles) constituting the aggregate are measured to obtain an average primary particle size.

When the silicon oxide-coated ultraviolet shielding particles of the present embodiment are immersed in an aqueous solution having a hydrogen ion index of 5 so as to be 0.05% by mass for 1 hour, the dissolution rate of metal ions in the ultraviolet shielding particles eluted in the aqueous solution. Is preferably 60% by mass or less, more preferably 20% by mass or less, and still more preferably 10% by mass or less.
Here, the reason why the elution rate of metal ions is preferably 60% by mass or less is that when the elution rate of metal ions exceeds 60% by mass, the stability of the silicon oxide-coated ultraviolet shielding particles themselves decreases, When silicon oxide-coated UV-shielding particles are applied to cosmetics, the eluted metal ions react with water-soluble polymers such as organic UV-screening agents and thickeners, resulting in reduced performance and discoloration as cosmetics. This is because it causes an increase or decrease in viscosity, and so on.

The elution rate of metal ions is, for example, by dispersing the silicon oxide-coated ultraviolet shielding particles in a buffer solution of pH = 5 so as to be 0.05% by mass and stirring for 1 hour, followed by solid-liquid separation. It is obtained by measuring the metal concentration with an ICP emission spectrometer.
The buffer solution at pH = 5 is not particularly limited as long as it is a buffer solution capable of dispersing the silicon oxide-coated ultraviolet shielding particles. For example, 500 mL of 0.1 mol / L potassium hydrogen phthalate aqueous solution, 0.1 mol A buffer solution having a total volume of 1000 mL by adding water after mixing 226 mL of / L sodium hydroxide aqueous solution is suitably used.

  The average primary particle diameter of the ultraviolet shielding particles is appropriately adjusted according to desired transparency and ultraviolet shielding properties. When it is desired to improve transparency, the average primary particle diameter of the ultraviolet shielding particles is preferably 1 nm or more and 50 nm or less. On the other hand, when it is desired to improve the ultraviolet shielding property, the average primary particle diameter of the ultraviolet shielding particles is preferably 50 nm or more and 500 nm or less. When it is desired to improve transparency and ultraviolet shielding properties, the average primary particle diameter of the ultraviolet shielding particles is preferably 25 nm or more and 250 nm or less.

A method for producing such a silicon oxide-coated ultraviolet shielding particle having a dense silicon oxide film is described in detail in International Publication No. 2014/171322. According to this production method, zinc oxide particles are coated with a silicon oxide film on the surface of the ultraviolet shielding particles using alkoxysilane, or sodium silicate and alkoxysilane, and fired at 200 ° C. to 600 ° C. Thus, silicon oxide-coated ultraviolet shielding particles having a dense silicon oxide film can be obtained.
In addition, when using an ultraviolet shielding particle with an average primary particle diameter of 50 nm or more, you may bake at 150 to 600 degreeC.

  Moreover, it is preferable that the silicon oxide film of this embodiment contains at least one selected from the group consisting of Mg, Ca, and Ba. The reason is as follows.

  In order to uniformly coat the entire surface of the ultraviolet shielding particles with a silica coating so that the decomposition rate of brilliant blue generated by the photocatalytic activity of the ultraviolet shielding particles is 3% or less, a material containing an alkali metal such as sodium silicate is used. It is preferable to form a silicon oxide film. However, if the alkali metal remains in the silicon oxide-coated ultraviolet shielding particles, the alkali ions are eluted when the silicon oxide-coated ultraviolet shielding particles are mixed with water, and the pH and viscosity are greatly fluctuated. Quality stability as a material will be impaired.

Therefore, by replacing the alkali metal contained in the silicon oxide film of the silicon oxide-coated ultraviolet shielding particles with at least one selected from the group consisting of Mg, Ca and Ba, oxidation of the silicon oxide-coated ultraviolet shielding particles is performed. Alkali metal contained in the silicon coating is removed from the silicon oxide coating of the silicon oxide-coated ultraviolet shielding particles.
On the other hand, at least one selected from the group consisting of Mg, Ca, and Ba substituted with an alkali metal contained in the silicon oxide film is present in the silicon oxide film of the silicon oxide-coated ultraviolet shielding particles after the substitution. . These substituted Mg, Ca, and Ba exist as magnesium silicate, calcium silicate, barium silicate, and the like that have low solubility in water.

  As a result of the substitution, the total mass percentage of at least one selected from the group consisting of Mg, Ca and Ba contained in the silicon oxide film of the silicon oxide-coated ultraviolet shielding particles is the amount of the alkali metal contained in the silicon oxide film. Greater than mass percentage. Therefore, even if this silicon oxide-coated ultraviolet-ray shielding particle is mixed in the aqueous phase, the elution of alkali metal can be suppressed, fluctuations in pH and viscosity can be suppressed, and the quality stability as a cosmetic can be maintained. Can do.

The silicon oxide-coated ultraviolet shielding particles of the present embodiment preferably contain at least one selected from the group consisting of Mg, Ca and Ba.
In the silicon oxide-coated ultraviolet shielding particles, the total mass percentage of at least one selected from the group consisting of Mg, Ca and Ba contained in the silicon oxide film is greater than the mass percentage of the alkali metal contained in the silicon oxide film. It is preferable that it is large. Furthermore, the ratio of the mass percentage of the alkali metal contained in the silicon oxide film to the total mass percentage of at least one selected from the group consisting of Mg, Ca and Ba contained in the silicon oxide film (mass of alkali metal Percentage / (total mass percentage of at least one selected from the group consisting of Mg, Ca and Ba) is preferably 0.001 or more and 0.6 or less, preferably 0.01 or more and 0.5 or less. More preferably, it is 0.1 or more and 0.4 or less.
In the present embodiment, the alkali metal refers to a generally known metal, specifically, lithium (Li), sodium (Na), potassium (K), rubidium (Rb), cesium (Cs). And at least one selected from the group consisting of francium (Fr).

  Here, the reason why the total mass percentage of at least one selected from the group consisting of Mg, Ca and Ba contained in the silicon oxide film is larger than the mass percentage of the alkali metal contained in the silicon oxide film is as follows. The main factor of fluctuation of the hydrogen ion index (pH) in the initial stage of silicon oxide-coated ultraviolet shielding particles is not the metal ions eluted from the ultraviolet shielding particles but the elution of alkali metal ions contained in the silicon oxide film. It is.

The mass percentage of the alkali metal contained in the silicon oxide film in the silicon oxide-coated ultraviolet shielding particles is preferably 0.8% by mass or less, more preferably 0.6% by mass or less, and 0.2% by mass. More preferably, it is% or less.
The lower limit of the mass percentage of the alkali metal contained in the silicon oxide film can be arbitrarily selected. The mass percentage of the alkali metal may be 0% by mass, and may be 0.0001% by mass or more, 0.001% by mass or more, for example, as another example.

  The total mass percentage of at least one selected from the group consisting of Mg, Ca and Ba contained in the silicon oxide film in the silicon oxide-coated ultraviolet shielding particles is 0.01% by mass or more and 1% by mass or less. Is preferred.

  The mass percentage (mass%) of alkali metal, Mg, Ca and Ba contained in the silicon oxide-coated ultraviolet shielding particles (silicon oxide film) can be measured by atomic absorption spectrometry.

The silicon oxide-coated ultraviolet shielding particles of the present embodiment are prepared by mixing water and 0.2 part by mass of an alkyl-modified carboxyvinyl polymer, and adjusting the pH to 6.0 with 2.5 mol / L sodium hydroxide 46.0% by mass. Part, a composition comprising 50 parts by mass of the above-mentioned silicon oxide-coated ultraviolet shielding particles and 4.0 parts by mass of glycerin and decamethylcyclopentasiloxane are mixed at a mass ratio of 1: 1, and dispersion treatment is carried out with ultrasound for 10 minutes. The mixture prepared in this way was allowed to stand for 20 hours, and then the 360 nm spectral transmittance of the oil phase of the mixture was 100%, and 10 parts by mass of the composition and 90 parts by mass of the carboxyvinyl polymer gel were mixed. When the mixture is sandwiched between glass slides and observed with an optical microscope, the particle size of the aggregates observed is 50 μm or less.
The carboxyvinyl polymer gel was prepared by dissolving 1.5 g of carbomer (trade name: Carbopol Ultraz 10 polymer, manufactured by Lubrizol Advanced Materials) in pure water, and then dropping 10% by mass aqueous sodium hydroxide solution. Means an aqueous solution with a pH of 7.5 containing 1.5% by mass of carbomer.

  Examples of the alkyl-modified carboxyvinyl polymer include those described later.

  Decamethylcyclopentasiloxane is one of cyclic siloxanes, and cyclic siloxane is a general term for cyclic organic compounds. Examples of the cyclic siloxane include hexamethylcyclotrisiloxane, octamethylcyclotetrasiloxane, decamethylcyclopentasiloxane, and the like. Decamethylcyclopentasiloxane is used in cosmetics.

  Spectral transmittance (diffusion transmittance) of 360 nm of the oil phase of the above mixed solution is obtained by collecting the oil phase from the mixed solution and using a quartz cell with an optical path length of 1 cm to SPF analyzer UV-1000S (manufactured by Labsphere) The transmittance value at 360 nm was used.

  When the spectral transmittance at 360 nm of the oil phase of the mixed solution is less than 100%, the silicon oxide-coated ultraviolet shielding particles are partially dispersed not only in the water phase but also in the oil phase. When blended in the phase, it is not preferable because it may partially move from the aqueous phase to the oil phase over time and impair the stability of the formulation.

  When observed with an optical microscope across the glass slide of the above mixture, the particle diameter of the aggregates observed is the maximum in three fields of 13.5 μm × 18 μm obtained at 200 times the optical microscope. The major axis of the aggregate was measured.

When measuring the particle size of the aggregate, the reason why the above composition and the carboxyvinyl polymer gel are mixed is that water and 0.2 parts by mass of the alkyl-modified carboxyvinyl polymer are mixed and 2.5 mol / L water is mixed. Aggregates at the time of mixing carboxyvinyl polymer gel with a composition comprising 46.0 parts by mass of a gel adjusted to pH 6.0 with sodium oxide, 50 parts by mass of the above-mentioned silicon oxide-coated ultraviolet shielding particles and 4.0 parts by mass of glycerin. This is because, when the product is produced, aggregates are produced when the silicon oxide-coated ultraviolet shielding particles are blended with the aqueous composition, and the desired ultraviolet shielding performance (SPF) may not be obtained.
What is mentioned later is mentioned as a carboxy vinyl polymer used for a carboxy vinyl polymer gel.

  When the above mixture is sandwiched between glass slides and observed with an optical microscope, if the maximum particle size of the observed aggregate exceeds 50 μm, the silicon oxide-coated ultraviolet shielding particles aggregate in the aqueous composition. It shows that it is easy. When such silicon oxide-coated ultraviolet shielding particles are blended in an aqueous composition, it is difficult to uniformly apply the silicon oxide-coated ultraviolet shielding particles to the skin. As a result, the desired ultraviolet shielding performance (SPF) cannot be obtained.

The silicon oxide-coated ultraviolet shielding particles of this embodiment are excellent in ultraviolet shielding properties even when applied to water-based cosmetics.
According to the silicon oxide-coated ultraviolet shielding particles of this embodiment, even when applied to the aqueous phase of an oil-in-water cosmetic, aggregation of the silicon oxide-coated ultraviolet shielding particles is suppressed, and the ultraviolet shielding properties are excellent.

[Method for producing silicon oxide-coated ultraviolet shielding particles]
An example of a method for producing silicon oxide-coated ultraviolet shielding particles in this embodiment will be described.
The method for producing silicon oxide-coated ultraviolet shielding particles in the present embodiment is a production method having a surface treatment step of treating the surface of silicon oxide-coated ultraviolet shielding particles with a predetermined organosilicon compound, for example.
The silicon oxide-coated ultraviolet shielding particles comprise a composite particle obtained by coating the surface of the ultraviolet shielding particles with silicon oxide containing an alkali metal, and at least one selected from the group consisting of Mg, Ca and Ba, and water. A step of mixing in a solution containing the alkali metal and replacing the alkali metal contained in the silicon oxide with at least one selected from the group consisting of Mg, Ca and Ba (hereinafter referred to as “substitution step”). You may use what was produced by.

In addition, the ultraviolet shielding particle | grains which coat | cover the silicon oxide containing the alkali metal before a substitution process, or the silicon oxide covering ultraviolet shielding containing at least 1 sort (s) selected from the group which consists of Mg, Ca, and Ba after a substitution process At least one of particles, an alkoxysilane and an oligomer of alkoxysilane of 10 mer or less, a catalyst, and water are added, and the mixture is reacted by stirring for 30 minutes to 24 hours and firing. By doing so, you may provide the process in which a silicon oxide film with a higher condensation degree is formed. This step may be performed separately from the surface treatment step or at the same time.
Next, a method for producing silicon oxide-coated ultraviolet shielding particles will be described in detail.

The ultraviolet shielding particles formed by coating silicon oxide containing an alkali metal are oxidized on the surface of the ultraviolet shielding particles by reacting a silicate containing an alkali metal such as sodium silicate with the ultraviolet shielding particles. Those coated with silicon may be used. Alternatively, commercially available ultraviolet shielding particles coated with silicon oxide may be used.
Examples of the method for coating the surface of the ultraviolet shielding particles with silicon oxide include, for example, JP-A-03-183620, JP-A-11-256133, JP-A-11-3032015, JP-A-2007-016111, and the like. The methods described can be used.

Although the method of coat | covering the surface of a ultraviolet-ray shielding particle with a silicon oxide is selected as needed, For example, the following methods are mentioned.
First, the ultraviolet shielding particles and water are mixed, and then the ultraviolet shielding particles are ultrasonically dispersed in water to prepare an aqueous suspension containing the ultraviolet shielding particles.
Next, the aqueous suspension containing the ultraviolet shielding particles is heated, and while the suspension is stirred, an aqueous sodium silicate solution is added and left to stand for 10 to 60 minutes.
Next, while stirring the suspension, an acid such as dilute sulfuric acid is added to adjust the pH to 5 to 9, and the mixture is allowed to stand for 30 minutes to 5 hours.
Next, this reaction solution is subjected to solid-liquid separation, and the resulting reaction product is washed with a solvent such as water, dried at about 100 ° C. to 200 ° C., and coated with silicon oxide containing an alkali metal. UV shielding particles obtained.

"Replacement process"
The replacement step needs to be performed after the step of coating the surface of the ultraviolet shielding particles with silicon oxide containing an alkali metal. The reason is that when an alkali metal-containing silicate and at least one selected from the group consisting of Mg, Ca and Ba are mixed in a solution containing water, magnesium silicate and calcium silicate are used as impurities. And at least one precipitate of barium silicate is produced. Therefore, the substitution step is preferably incorporated in any stage from the step of coating the surface of the ultraviolet shielding particles with silicon oxide by the neutralization reaction of silicate to the step of the drying step. . According to such a method, the reaction process can be reduced, and the silicon oxide-coated ultraviolet shielding particles in the present embodiment can be produced at low cost.

In the replacement step, first, ultraviolet shielding particles coated with silicon oxide containing an alkali metal and at least one selected from the group consisting of Mg, Ca and Ba are added to a solution containing water and mixed. To do.
It does not specifically limit as a solution containing water, It selects as needed. As the solution containing water, for example, water or a solution obtained by mixing water and a solvent compatible with water is used.
As a solvent compatible with water, for example, a protic polar solvent such as methanol, ethanol and 2-propanol, and an aprotic polar solvent such as acetone and tetrahydrofuran are preferable. Among these, protic polar solvents such as methanol, ethanol, and 2-propanol are more preferable.

The reaction temperature in this mixing process is not particularly limited, and is adjusted as necessary. What is necessary is just more than the freezing point of the solvent in the liquid mixture containing the ultraviolet shielding particle | grains coat | covered with the silicon oxide, at least 1 sort (s) selected from the group which consists of Mg, Ca, and Ba, and the solution containing water.
Further, the reaction proceeds even when the mixed solution is left standing, but in order to increase the reaction efficiency, it is preferable to react the mixed solution while stirring.
The reaction time is not particularly limited and is selected as necessary. The reaction time is preferably 1 hour or longer.

  By this mixing treatment, the alkali metal in the ultraviolet shielding particles coated with silicon oxide is substituted with at least one selected from the group consisting of Mg, Ca and Ba, and the ultraviolet shielding particles coated with silicon oxide. Elute into the mixture. On the other hand, at least one ion selected from the group consisting of Mg, Ca and Ba substituted with an alkali metal is taken into the silicon oxide-coated ultraviolet shielding particles by substitution with an alkali metal, and as a result, Mg, Ca and Ba The silicon oxide-coated ultraviolet shielding particles containing at least one selected from the group consisting of:

  The content of at least one selected from the group consisting of Mg, Ca, and Ba contained in the mixed solution is not particularly limited and is selected as necessary. In order to ion-exchange alkali ions such as Na and K in the ultraviolet shielding particles coated with silicon oxide with at least one ion selected from the group consisting of Mg, Ca and Ba, The content of at least one selected from the group consisting of Mg, Ca and Ba is preferably not less than the sum of the molar equivalents of alkali metals in the ultraviolet shielding particles coated with silicon oxide.

The raw material for providing at least one selected from the group consisting of Mg, Ca and Ba is not particularly limited as long as it is an inorganic salt containing these elements. Examples of raw materials for providing Mg include magnesium chloride, magnesium sulfate, and magnesium nitrate. Examples of the raw material for providing Ca include calcium chloride and calcium nitrate. As a raw material for providing Ba, for example, barium chloride, barium nitrate or the like is preferably used.
These raw materials may be used as a solid or in an aqueous solution state.

  The mixed solution containing the silicon oxide-coated ultraviolet shielding particles produced by this substitution step is subjected to solid-liquid separation, and again obtained at least selected from the group consisting of the silicon oxide-coated ultraviolet shielding particles and Mg, Ca and Ba 1 type may be mixed in the solution containing water, and the substitution process of the alkali metal in this silicon oxide coating zinc oxide and at least 1 type selected from the group which consists of Mg, Ca, and Ba may be performed. . This replacement step may be repeated a plurality of times.

  In the case where the silica film is further densified, at least one of alkoxysilane and an oligomer of alkoxysilane of 10-mer or less is added to the mixed solution containing the silicon oxide-coated ultraviolet shielding particles generated by the substitution step, and A catalyst may be added and mixed, and heat treatment may be performed at 150 ° C. or more and less than 600 ° C.

"Surface treatment process"
A surface treatment process will not be specifically limited if it is a method which can surface-treat the organosilicon compound represented by following General formula (2). In the surface treatment step, a dry method or a wet method may be used.
X _n Si (OR) _4-n (2)
(Wherein X is an alkyl group, alkenyl group or cycloalkyl group, R is a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, n is an integer, and 0 <n <4.)

  Examples of the surface treatment step include a method in which the organosilicon compound represented by the general formula (2) is added to and mixed with the mixed solution containing the silicon oxide-coated ultraviolet shielding particles generated by the substitution step. It is done. The surface treatment step may be performed at room temperature or may be performed by heating.

  Specific examples of the organosilicon compound include, for example, methyltrimethoxysilane, methyltriethoxysilane, methyltripropoxysilane, methyltriisopropoxysilane, methyltributoxysilane, ethyltrimethoxysilane, ethyltriethoxysilane, ethyltripropoxy. Silane, ethyltriisopropoxysilane, ethyltributoxysilane, n-propyltrimethoxysilane, n-propyltriethoxysilane, n-propyltripropoxysilane, n-propyltriisopropoxysilane, n-propyltributoxysilane, isopropyl Trimethoxysilane, isopropyltriethoxysilane, isopropyltripropoxysilane, isopropyltriisopropoxysilane, isopropyltributoxysilane, butyltrimethyl Xysilane, butyltriethoxysilane, butyltripropoxysilane, butyltriisopropoxysilane, sec-butyltrimethoxysilane, sec-butyltriethoxysilane, sec-butyltripropoxysilane, sec-butyltriisopropoxysilane, t-butyl Alkylalkoxysilanes such as trimethoxysilane, t-butyltriethoxysilane, t-butyltripropoxysilane, t-butyltriisopropoxysilane; vinyltrimethoxysilane, vinyltriethoxysilane, vinyltripropoxysilane, vinyltriisopropoxy Alkenylalkoxysilanes such as silane; cyclopropyltrimethoxysilane, cyclopropyltriethoxysilane, cyclopropyltripropoxysilane, cyclopropyltrii Propoxysilane, cyclobutyltrimethoxysilane, cyclobutyltriethoxysilane, cyclobutyltripropoxysilane, cyclobutyltriisopropoxysilane, cyclopentyltrimethoxysilane, cyclopentyltriethoxysilane, cyclopentyltripropoxysilane, cyclopentyltriisopropoxysilane, cyclohexyl Examples thereof include cycloalkylsilanes such as trimethoxysilane, cyclohexyltriethoxysilane, cyclohexyltripropoxysilane, and cyclohexyltriisopropoxysilane.

  Next, the liquid mixture containing the silicon oxide-coated ultraviolet shielding particles produced by the surface treatment step is subjected to solid-liquid separation by atmospheric pressure filtration, vacuum filtration, pressure filtration, centrifugation, or the like. The obtained solid material is washed with a solvent such as water to obtain silicon oxide-coated ultraviolet shielding particles.

Since the thus obtained silicon oxide-coated ultraviolet shielding particles contain water, it is preferably dried to remove the water.
The drying temperature of the silicon oxide-coated ultraviolet shielding particles is not particularly limited. Usually, it is preferable to dry the silicon oxide-coated ultraviolet shielding particles at a temperature of 100 ° C. or higher. Moreover, when drying at the temperature of 80 degrees C or less, reduced pressure drying is preferable.
Through the above steps, the silicon oxide-coated ultraviolet shielding particles in the present embodiment can be produced.

When the step of densifying the silica coating and the surface treatment step are performed simultaneously, for example, the following may be performed.
In a mixed solution containing the silicon oxide-coated ultraviolet shielding particles before the substitution step or the silicon oxide-coated ultraviolet shielding particles produced by the substitution step, at least one of an alkoxysilane and an oligomer of alkoxysilane of 10-mer or less, a catalyst, The organic silicon compound represented by the general formula (2) is added and mixed. Mixing may be performed at room temperature or may be performed by heating.
Next, the liquid is removed from the mixed liquid by solid-liquid separation and dried, and the obtained dried product is subjected to heat treatment (firing) at 200 ° C. or higher and lower than 600 ° C. Shielding particles can be made.

[Aqueous composition containing silicon oxide-coated ultraviolet shielding particles]
The silicon oxide-coated ultraviolet shielding particle-containing aqueous composition of the present embodiment contains the silicon oxide-coated ultraviolet shielding particles of the present embodiment and water.

The water is not particularly limited as long as it is commonly used in cosmetics, and pure water, ion exchange water, distilled water, purified water, ultrapure water, natural water, alkaline ionized water, deep water, etc. are used. It is done.
The water content in the aqueous composition containing silicon oxide-coated ultraviolet shielding particles is appropriately adjusted according to the desired properties. From the viewpoint of improving the usability of the silicon oxide-coated ultraviolet shielding particle-containing aqueous composition, the water content is preferably 10% by mass to 99% by mass, and more preferably 20% by mass to 95% by mass. More preferably, it is 40 mass% or more and 94 mass% or less.

In the silicon oxide-coated ultraviolet shielding particle-containing aqueous composition of the present embodiment, the average dispersed particle size of the silicon oxide-coated ultraviolet shielding particles is preferably 10 nm or more and 2 μm or less, and more preferably 20 nm or more and 800 nm or less. Preferably, it is 25 nm or more and 500 nm or less.
If the average dispersed particle diameter of the silicon oxide-coated ultraviolet shielding particles is 10 nm or more, the crystallinity of the silicon oxide-coated ultraviolet shielding particles will not be lowered, and thus sufficient ultraviolet shielding properties can be exhibited. On the other hand, if the average dispersed particle size of the silicon oxide-coated ultraviolet shielding particles is 2 μm or less, glare, creaking, etc. will not occur, the feel of use when formulated into cosmetics will be improved, and the dispersion stability will be improved. And a stable composition is obtained.
In the present embodiment, the average dispersed particle diameter means an average value of secondary particle diameters measured by a dynamic light scattering method.
In terms of obtaining a transparent silicon oxide-coated ultraviolet shielding particle-containing aqueous composition, the average dispersed particle size is preferably 10 nm or more and 200 nm or less.

The content of the silicon oxide-coated ultraviolet shielding particles in the silicon oxide-coated ultraviolet shielding particle-containing aqueous composition of the present embodiment may be appropriately adjusted in order to obtain a desired ultraviolet shielding performance, and is not particularly limited. The content of the silicon oxide-coated ultraviolet shielding particles is preferably 1% by mass or more and 80% by mass or less, more preferably 20% by mass or more and 70% by mass or less, and 30% by mass or more and 60% by mass. More preferably, it is as follows.
Here, the content of the silicon oxide-coated ultraviolet shielding particles is preferably 1% by mass or more and 80% by mass or less. The reason is that if the content of the silicon oxide-coated ultraviolet shielding particles is 1% by mass or more, the silicon oxide-coated ultraviolet shielding particle-containing aqueous composition can exhibit sufficient ultraviolet shielding performance. As a result, it is necessary to add a large amount of an aqueous composition containing silicon oxide-coated ultraviolet shielding particles in order to exhibit desired ultraviolet shielding performance when the aqueous composition containing silicon oxide-coated ultraviolet shielding particles is added to cosmetics and the like. Therefore, an increase in manufacturing cost can be suppressed. On the other hand, when the content of the silicon oxide-coated ultraviolet shielding particles is 80% by mass or less, the viscosity of the silicon oxide-coated ultraviolet shielding particles-containing aqueous composition does not increase, and the dispersion stability of the silicon oxide-coated ultraviolet shielding particles is improved. Thus, sedimentation of the silicon oxide-coated ultraviolet shielding particles can be suppressed.

  The aqueous composition containing the silicon oxide-coated ultraviolet shielding particles of this embodiment may be adjusted to pH 6 to 7 by adding a weak acid or a pH buffer solution used in cosmetics such as citric acid. By adding such a weak acid, the pH of the composition can be maintained at 7 or less over a long period of time.

The silicon oxide-coated ultraviolet shielding particle-containing aqueous composition of the present embodiment is a general composition such as a dispersant, a stabilizer, a water-soluble binder, a water-soluble vinyl polymer, a thickener, and alcohols, as long as the characteristics are not impaired. Additives used in may be included.
From the viewpoint of improving the dispersion stability of the aqueous composition, it is preferable to contain at least one of a water-soluble vinyl polymer and alcohols.

  Dispersants include anionic surfactants, cationic surfactants, amphoteric surfactants, nonionic surfactants, silane coupling agents such as organoalkoxysilanes and organochlorosilanes, polyether-modified silicones, amino-modified silicones, etc. The modified silicone is preferably used. The type and amount of these dispersants may be appropriately selected according to the particle size of the silicon oxide-coated ultraviolet shielding particles and the type of the target dispersion medium, and only one of the above dispersants may be used alone. Alternatively, two or more kinds may be mixed and used.

  As the water-soluble binder, polyvinyl alcohol (PVA), polyvinyl pyrrolidone, hydroxycellulose, polyacrylic acid, or the like can be used.

The water-soluble vinyl polymer is not particularly limited as long as it is a vinyl polymer that can be mixed with water at an arbitrary ratio and can be used in cosmetics.
As such a water-soluble vinyl polymer, a carboxyvinyl polymer, an alkyl-modified carboxyvinyl polymer, an alkyl acrylate / methacrylic acid / polyoxyethylene copolymer, and the like can be used. These water-soluble vinyl polymers may be used alone or in combination of two or more.

  Examples of the carboxyvinyl polymer include Carbopol (registered trademark) 940, Carbopol (registered trademark) 941, Carbopol (registered trademark) 980, Carbopol (registered trademark) 981, Carbopol (registered trademark) Ultrez 10 (manufactured by Lubrizol Advanced Materials). What is known by a brand name is mentioned.

  Examples of the alkyl-modified carboxyvinyl polymer are known under the trade names of Carbopol (registered trademark) 1342, PEMULEN (registered trademark) TR-1, and PEMULEN (registered trademark) TR-2 (manufactured by Lubrizol Advanced Materials). Is mentioned.

Examples of the alkyl acrylate / methacrylic acid / polyoxyethylene copolymer include (acrylates / steareth methacrylate-20) copolymer, (acrylates / beheneth methacrylate-25) copolymer, and (acrylates / steare methacrylate-20) cross. Polymers. Further, examples of the alkyl acrylate / methacrylic acid / polyoxyethylene copolymer include Acurin (registered trademark) 22, Aculin (registered trademark) 28, and Aculin (registered trademark) 88 commercially available from Rohm & Haas.
Among these alkyl acrylate / alkyl methacrylate / polyoxyethylene copolymers, Aculine (registered trademark) 22 (Acrylates / Stearless Methacrylate Methacrylate) copolymer is particularly preferred because it is not sticky and has a good feeling in use. is there.

When the aqueous composition containing the silicon oxide-coated ultraviolet shielding particles of the present embodiment contains a water-soluble vinyl polymer, the content of the water-soluble vinyl polymer with respect to 100 parts by mass of the silicon oxide-coated ultraviolet shielding particles is 0.02 mass. Part or more and 6.0 parts by weight or less, preferably 0.1 parts by weight or more and 5.0 parts by weight or less, more preferably 0.2 parts by weight or more and 4.5 parts by weight or less. More preferably.
When the content of the water-soluble vinyl polymer with respect to 100 parts by mass of the silicon oxide-coated ultraviolet shielding particles is 0.02 parts by mass or more, dispersion stability is ensured and a uniform composition is obtained. On the other hand, if the content of the water-soluble vinyl polymer with respect to 100 parts by mass of the silicon oxide-coated ultraviolet shielding particles is 6.0 parts by mass or less, the viscosity is in an appropriate range and stirring is easy. can get.

Moreover, in the silicon oxide-coated ultraviolet shielding particle-containing aqueous composition of the present embodiment, the content of the water-soluble vinyl polymer is preferably 0.01% by mass or more and 1.0% by mass or less, and 0.05 More preferably, the content is greater than or equal to mass% and less than or equal to 0.75 mass%, more preferably greater than or equal to 0.1 mass% and less than or equal to 0.5 mass%.
In the silicon oxide-coated ultraviolet shielding particle-containing aqueous composition of the present embodiment, the total content of each component is 100% by mass, and the total content of each component does not exceed 100% by mass.

The thickener is not particularly limited as long as it is a thickener used in a cosmetic when the silicon oxide-coated ultraviolet shielding particle-containing aqueous composition of the present embodiment is applied to the cosmetic. Examples of the thickener include natural water-soluble polymers such as gelatin, casein, collagen, hyaluronic acid, albumin, starch, methyl cellulose, ethyl cellulose, methyl hydroxypropyl cellulose, carboxymethyl cellulose, hydroxymethyl cellulose, hydroxypropyl cellulose, carboxymethyl cellulose. Semi-synthetic polymers such as sodium and propylene glycol alginate, synthetic polymers such as polyvinyl alcohol, polyvinyl pyrrolidone, carbomer (carboxyvinyl polymer), polyacrylate and polyethylene oxide, inorganic minerals such as bentonite, laponite and hectorite Are preferably used. These thickeners may be used individually by 1 type, and may be used in combination of 2 or more type.
Among these thickeners, synthetic polymers are preferable, and carbomers (carboxyvinyl polymers) are more preferable.

Here, when a carbomer is used as the thickener, the carbomer content in the silicon oxide-coated ultraviolet shielding particle-containing aqueous composition of the present embodiment is preferably 0.01% by mass or more and 10% by mass or less. More preferably, it is 0.01 mass% or more and 3 mass% or less.
If the carbomer content in the silicon oxide-coated ultraviolet shielding particle-containing aqueous composition of the present embodiment is 0.01% by mass or more, a thickening effect can be obtained. On the other hand, if the carbomer content is 10% by mass or less, the viscosity of the silicon oxide-coated ultraviolet shielding particle-containing aqueous composition can be prevented from becoming too high. It is easy to ride on the skin when spread and applied, and there are no problems such as reduced feeling of use.

  The hydrogen ion index (pH) in the silicon oxide-coated ultraviolet shielding particle-containing composition when a carbomer is used as a thickener is preferably 5 or more and 10 or less, more preferably 6 or more and 10 or less. More preferably, it is 7 or more and 9 or less. By setting the pH in the silicon oxide-coated ultraviolet shielding particle-containing aqueous composition of the present embodiment within the above range, changes with time such as viscosity can be suppressed.

Alcohols are not particularly limited as long as they can be used in cosmetics. For example, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, octanol, glycerin, 1,3-butylene glycol, A monohydric alcohol or polyhydric alcohol having 1 to 6 carbon atoms such as propylene glycol and sorbitol can be used.
Among these alcohols, glycerin is preferable in terms of being widely used in cosmetics due to the improvement in the feel of the cosmetics and the moisturizing effect.

In the case where the alcohol is contained in the silicon oxide-coated ultraviolet shielding particle-containing aqueous composition of the present embodiment, the alcohol content is 10 parts by mass or more and 100 parts by mass with respect to 100 parts by mass of the silicon oxide-coated ultraviolet shielding particles. Or less, more preferably 20 parts by mass or more and 50 parts by mass or less.
When the content of the alcohol is 10 parts by mass or more with respect to 100 parts by mass of the silicon oxide-coated ultraviolet shielding particles, the dispersibility of the silicon oxide-coated ultraviolet shielding particles can be further improved. On the other hand, if the content of the alcohol is 100 parts by mass or less with respect to 100 parts by mass of the silicon oxide-coated ultraviolet shielding particles, the stickiness when the silicon oxide-coated ultraviolet shielding particle-containing aqueous composition of the present embodiment is blended in the cosmetics. Deterioration of touch can be suppressed.

  In the silicon oxide-coated ultraviolet shielding particle-containing aqueous composition of the present embodiment, the alcohol content is preferably 0.1% by mass to 30% by mass, more preferably 0.3% by mass to 25%. More preferably, it is at most 0.5 mass%, more preferably at least 0.5 mass% and at most 20 mass%.

The water-based composition containing the silicon oxide-coated ultraviolet shielding particles of this embodiment has a viscosity measured under accelerated conditions, for example, when stored at 40 ° C. and after 300 hours has elapsed, after the viscosity is reduced under the initial conditions. For example, the value divided by the viscosity after 15 hours is preferably 0.8 or more and 1.2 or less.
In this way, by setting the value obtained by dividing the viscosity under accelerated conditions, that is, the viscosity after 300 hours by the viscosity after the initial viscosity reduction, within the above range, the silicon oxide-coated ultraviolet shielding particle-containing aqueous composition of the present embodiment The viscosity of the product can be maintained over the medium to long term.

When the silicon oxide-coated ultraviolet shielding particle-containing aqueous composition of the present embodiment has a silicon oxide-coated ultraviolet shielding particle content of 5% by mass and a coating film having a thickness of 12 μm is formed using this composition, the coating film The transmittance for light having a wavelength of 450 nm is preferably 40% or more, more preferably 45% or more, and still more preferably 50% or more.
Further, the SPF (Sun Protection Factor) value of this coating film is preferably 6.0 or more, and more preferably 6.5 or more.
The coating film transmittance and SPF value were determined by applying a silicon oxide-coated ultraviolet shielding particle-containing aqueous composition containing 5% by mass of silicon oxide-coated ultraviolet shielding particles onto a quartz substrate with a bar coater, and having a thickness of 12 μm. A coating film is formed, and the spectral transmittance of this coating film can be determined by measuring with SPF analyzer UV-1000S (manufactured by Labsphere).

  Further, an absorption spectrum can be calculated from the transmittance, integrated from 290 nm to the longer wavelength side of the absorption spectrum, and a wavelength at which the integrated area becomes 90% of the total integrated area of 290 nm to 400 nm can be calculated as the critical wavelength. The longer the wavelength, the higher the UVA shielding performance, and the critical wavelength is preferably 375 nm or more, more preferably 378 nm or more, and even more preferably 380 nm or more.

The method for producing the silicon oxide-coated ultraviolet shielding particle-containing aqueous composition of the present embodiment is not particularly limited as long as the above-described silicon oxide-coated ultraviolet shielding particles can be dispersed in water.
As a dispersion method used for such dispersion, a dispersion method using a known dispersion apparatus can be used. As the dispersing device, for example, a dispersing method using a bead mill using zirconia beads, a ball mill, a homogenizer, an ultrasonic disperser, a kneader, a three-roll mill, a rotation / revolution mixer, and the like is suitably used in addition to a stirrer.
The time required for the dispersion treatment may be a time sufficient to uniformly disperse the silicon oxide-coated ultraviolet shielding particles in water.

  According to the silicon oxide-coated ultraviolet shielding particle-containing aqueous composition of the present embodiment, since the silicon oxide-coated ultraviolet shielding particle of the present embodiment is included, the ultraviolet shielding property is excellent even when applied to an aqueous cosmetic.

[Cosmetics]
The cosmetic material of this embodiment contains at least one of the silicon oxide-coated ultraviolet shielding particles of this embodiment and the silicon oxide-coated ultraviolet shielding particle-containing aqueous composition of this embodiment, and a cosmetic base material.
It is preferable that the cosmetic of this embodiment contains water.

Here, the cosmetic base material means various raw materials forming the main body of the cosmetic, and examples thereof include an oily raw material, an aqueous raw material, a surfactant, and a powder raw material.
Examples of oily raw materials include fats and oils, higher fatty acids, higher alcohols, ester oils, and the like.
Examples of the aqueous raw material include purified water, alcohol, and thickener.
Examples of the powder raw material include colored pigments, white pigments, pearl agents, extender pigments, and the like.

The cosmetic of the present embodiment includes, for example, the silicon oxide-coated ultraviolet shielding particles of the present embodiment and the aqueous composition containing the silicon oxide-coated ultraviolet shielding particles of the present embodiment, such as emulsion, cream, foundation, lipstick, blusher, and eye shadow. It is obtained by blending with a cosmetic base material of the above by a known method.
Further, the cosmetic of the present embodiment is prepared by blending the silicon oxide-coated ultraviolet shielding particles of the present embodiment or the aqueous composition containing the silicon oxide-coated ultraviolet shielding particles of the present embodiment in an oil phase or an aqueous phase, and an O / W type. Alternatively, it can also be obtained by blending with a cosmetic base material after a W / O type emulsion.

  What is necessary is just to adjust suitably content of the silicon oxide coating | coated ultraviolet shielding particle in cosmetics according to a desired characteristic, for example, even if the minimum of content of silicon oxide coating | coated ultraviolet shielding particle is 0.01 mass% or more It may be 0.1% by mass or more, or 1% by mass or more. Further, the upper limit of the content of the silicon oxide-coated ultraviolet shielding particles may be 50% by mass or less, 40% by mass or less, or 30% by mass or less.

  According to the cosmetic material of this embodiment, since it contains at least one of the silicon oxide-coated ultraviolet shielding particles of this embodiment and the silicon oxide-coated ultraviolet shielding particle-containing aqueous composition of this embodiment, it has excellent ultraviolet shielding properties. .

[Oil-in-water cosmetics]
The oil-in-water cosmetic of the present embodiment contains at least one of the silicon oxide-coated ultraviolet shielding particles of the present embodiment and the aqueous composition containing the silicon oxide-coated ultraviolet shielding particles of the present embodiment in an aqueous phase.

The oil-in-water cosmetic of the present embodiment includes at least one of the silicon oxide-coated ultraviolet shielding particles of the present embodiment and the aqueous composition containing the silicon oxide-coated ultraviolet shielding particles of the present embodiment in an aqueous phase. An oil-in-water emulsion containing an oil component.
The aqueous phase may contain additives generally used in water-based cosmetics, such as dispersants, stabilizers, water-soluble binders (water-soluble polymers), thickeners, and alcohols, as necessary. Good.
Additives commonly used in cosmetics such as oil-soluble preservatives, UV absorbers, oil-soluble drugs, oil-soluble pigments, oil-soluble proteins, vegetable oils, animal oils, solvents, etc. May be included as appropriate.

The oil component is not particularly limited as long as it is used in cosmetics, and an oil component that can dissolve a desired organic ultraviolet shielding agent is appropriately selected.
Such an oil component preferably contains at least one selected from the group consisting of higher alcohols, higher fatty acids, and fatty acid esters formed by combining higher alcohols and higher fatty acids. When the oil component contains these components, the firmness and moisturizing feeling of the cosmetic are improved, and the sustainability of these effects is improved. In addition, a liquid organic ultraviolet absorber such as ethylhexyl methoxycinnamate can be used as the oil component.

  As the higher alcohol, for example, capryl alcohol, lauryl alcohol, stearyl alcohol, oleyl alcohol, myristyl alcohol, cetyl alcohol, cholesterol, phytosterol and the like are preferably used. These higher alcohols may be used alone or in combination of two or more.

  As the higher fatty acid, for example, a saturated or unsaturated fatty acid having 12 to 24 carbon atoms is preferably used. For example, myristic acid, palmitic acid, stearic acid, isostearic acid, linoleic acid, arachidonic acid and the like are preferably used. It is done. These higher fatty acids may be used alone or in combination of two or more.

Examples of fatty acid esters include cetyl myristate, octyldodecyl myristate, isopropyl myristate, myristyl myristate, 2-hexyldecyl myristate, octyl palmitate, isopropyl palmitate, butyl stearate, stearyl stearate, octyl stearate , Isocetyl stearate, glycol distearate, cetyl 2-ethylhexanoate, 2-ethylhexyl stearate, stearyl stearate, cholesteryl isostearate, isocetyl isostearate, isononyl isononanoate, ethyl oleate, decyl oleate, oleyl oleate, Diisopropyl sebacate, dioctyl sebacate, hexyldecyl dimethyloctanoate, cetyl octanoate, neodioctanoate Emissions chill glycol, hexyl laurate, tetra octanoate pentaerythrityl like are suitably used. These fatty acid esters may be used alone or in combination of two or more.
In the present embodiment, from the viewpoint of suppressing separation of the aqueous phase and the oil phase, it is preferable that the ester value of the fatty acid ester is low. Specifically, it is preferable to use a fatty acid ester having an ester value of 95 to 170. Examples of such fatty acid esters include octyldodecyl myristate (ester value 100 to 111), cetyl 2-ethylhexanoate (ester value 135 to 160), and the like.

The oil-in-water cosmetic of this embodiment preferably contains a chelating agent. By containing the chelating agent, it is possible to further suppress the hydrogen index fluctuation of the oil-in-water cosmetics over time.
The chelating agent is not particularly limited as long as it is used for cosmetics. As the chelating agent, for example, ethylenediaminetetraacetic acid (EDTA), ethyleneglycoldiaminetetraacetic acid, diethylenetriaminepentaacetic acid, citric acid, phytic acid, polyphosphoric acid, metaphosphoric acid and the like are used. Among these, ethylenediaminetetraacetic acid (EDTA) is preferable because of its high versatility.

The content of the chelating agent in the oil-in-water cosmetic is appropriately adjusted according to the desired performance, and is preferably 0.01% by mass or more and 1.0% by mass or less, for example.
Here, if content of a chelating agent is 0.01 mass% or more, in oil-in-water cosmetics, a desired characteristic will be acquired. On the other hand, if the content of the chelating agent is 1.0% by mass or less, the oil-in-water cosmetic can be used safely. For example, the amount of ethylenediaminetetraacetic acid (EDTA) in cosmetics is regulated to 1.0% by mass or less in the quasi-drug raw material standard.

The oil-in-water cosmetic of the present embodiment preferably contains an organic ultraviolet shielding agent in the oil phase.
The organic ultraviolet shielding agent is not particularly limited as long as it is used for cosmetics. Examples of the organic ultraviolet screening agent include anthranilates, cinnamic acid derivatives, salicylic acid derivatives, camphor derivatives, benzophenone derivatives, β, β'-diphenyl acrylate derivatives, benzotriazole derivatives, benzalmalonate derivatives, benzoates. Examples include imidazole derivatives, imidazolines, bisbenzoazolyl derivatives, p-aminobenzoic acid (PABA) derivatives, methylenebis (hydroxyphenylbenzotriazole) derivatives, and tinuvin. As the organic ultraviolet shielding agent, at least one selected from the above group is used.

The average dispersed particle diameter of the silicon oxide-coated ultraviolet shielding particles in the oil-in-water cosmetic of the present embodiment is preferably 10 nm or more and 2 μm or less, more preferably 20 nm or more and 800 nm or less, and 25 nm or more. And it is more preferable that it is 500 nm or less.
If the average dispersed particle diameter of the silicon oxide-coated ultraviolet shielding particles is 10 nm or more, the crystallinity of the silicon oxide-coated ultraviolet shielding particles will not be lowered, and thus sufficient ultraviolet shielding properties can be exhibited. On the other hand, if the average dispersed particle size of the silicon oxide-coated ultraviolet shielding particles is 2 μm or less, glare, creaking, etc. will not occur, the feel of use will be improved, the dispersion stability will be improved, and the stable oil-in-water A mold cosmetic is obtained.

The oil-in-water cosmetic of the present embodiment, in addition to the above-mentioned components, by appropriately adding other components, etc., such as milky lotion, cream, sunscreen, foundation, beauty serum, makeup base, lipstick, etc. It may be used in the form.
Other ingredients include inorganic UV screening agents such as zinc oxide and titanium oxide, organic UV screening agents, whitening agents, thickeners, additives commonly used in cosmetics, and cosmetic base materials. Can be mentioned.

  According to the oil-in-water cosmetic of the present embodiment, it contains at least one of the silicon oxide-coated ultraviolet shielding particles of the present embodiment and the silicon oxide-coated ultraviolet shielding particle-containing aqueous composition of the present embodiment. Excellent shielding properties.

[Method for producing oil-in-water cosmetics]
In the method for producing an oil-in-water cosmetic of the present embodiment, at least one of the silicon oxide-coated ultraviolet shielding particles of the present embodiment and the x-oxide-coated ultraviolet shielding particle-containing aqueous composition of the present embodiment is contained in the aqueous phase. The oil component is not particularly limited as long as it is a method capable of producing an oil-in-water (O / W) cosmetic containing an oil phase.

  For example, water, a silicon oxide-coated ultraviolet shielding particle-containing aqueous composition of the present embodiment, a pH adjuster, and an emulsifier are mixed in advance to obtain a mixture for an aqueous phase. And an oil component is added and mixed with this mixture for water phases, and the oil-in-water-type cosmetics of this embodiment are producible by setting it as an oil-in-water emulsion.

  In addition, when an alkyl-modified carboxyvinyl polymer or an alkyl acrylate / methacrylic acid / polyoxyethylene copolymer is contained in the aqueous composition containing silicon oxide-coated ultraviolet shielding particles, the alkyl portion serves as an emulsifier. Therefore, it is not necessary to add an emulsifier.

  The emulsifier is not particularly limited as long as it can be used in cosmetics to produce an oil-in-water emulsion. For example, a hydrophilic surfactant can be suitably used. Examples of the hydrophilic surfactant include glycerin, glycerin fatty acid ester, polyglycerin fatty acid ester, polyoxyethylene glycerin fatty acid ester, sorbitan fatty acid ester, propylene glycol. Fatty acid esters, polyoxyethylene (hereinafter abbreviated as “POE”) sorbitan fatty acid esters, POE sorbite fatty acid esters, POE glycerin fatty acid esters, POE fatty acid esters, POE alkyl ethers, POE alkyl phenyl ethers, POE castor oil, POE alkylamine, POE fatty acid amide and the like can be mentioned.

  In the case of containing an organic ultraviolet shielding agent, an oil component and an organic ultraviolet shielding agent are mixed in advance and then mixed and emulsified in a mixture for an aqueous phase.

  EXAMPLES Hereinafter, although an Example and a comparative example demonstrate this invention concretely, this invention is not limited by these Examples.

[Example 1]
Zinc oxide particles (average particle size 35 nm; manufactured by Sumitomo Osaka Cement) and water were mixed, and then ultrasonic dispersion was performed to prepare a zinc oxide aqueous suspension having a zinc oxide content of 20% by mass.
Next, this aqueous zinc oxide suspension is added to an aqueous sodium silicate solution containing 20% by mass of sodium silicate in terms of silicon oxide based on the mass of zinc oxide particles in the aqueous zinc oxide suspension. Stir to a suspension.

Then, this suspension was heated to 60 ° C., and diluted hydrochloric acid was gradually added while stirring the suspension to adjust the pH to 6.5-7. Thereafter, the mixture was allowed to stand for 2 hours, and then a calcium chloride aqueous solution (25% by mass of calcium chloride dihydrate) having the same mass as that of the zinc oxide particles in the suspension was further added and stirred for another 2 hours. Left to stand.
Next, the suspension was subjected to solid-liquid separation with a centrifuge, and the obtained solid was washed with water. Thereafter, the solid was dried at 150 ° C., and further subjected to heat treatment (baking) at 500 ° C. for 2 hours to produce silicon oxide-coated zinc oxide.
Next, the silicon oxide-coated zinc oxide and 2-propanol are mixed and then ultrasonically dispersed to prepare a silicon oxide-coated zinc oxide 2-propanol suspension having a silicon oxide-coated zinc oxide content of 10% by mass. did.

  Next, the suspension was heated to 60 ° C., and ammonia water and water were added to the suspension while stirring to adjust the pH to 10-11. The amount of water added was 120% by mass with respect to tetraethoxysilane in the tetraethoxysilane 2-propanol solution added later.

Further, a tetraethoxysilane 2-propanol solution was slowly added dropwise to this suspension so that the amount of tetraethoxysilane added was 15% by mass with respect to the total mass of zinc oxide in terms of silicon oxide.
Next, methyltriethoxysilane is added to this suspension so that the amount of methyltriethoxysilane becomes 0.5% by mass with respect to the total mass of the zinc oxide particles (the alkyl group is 0.04% by mass in the silicon oxide-coated zinc oxide particles). The solution was slowly added dropwise and stirring was continued for 6 hours.
After completion of the reaction, the suspension was subjected to solid-liquid separation using a centrifuge, and the obtained solid was dried at 150 ° C. Next, this dried product was heat-treated (calcined) at 500 ° C. for 3 hours to obtain silicon oxide-coated zinc oxide particles of Example 1.

"Preparation of aqueous composition containing silicon oxide coated zinc oxide particles"
Gel 46 prepared by mixing water and 0.2 parts by mass of an alkyl-modified carboxyvinyl polymer (trade name: PEMULEN TR-1, Lubrizol Advanced Materials) and adjusting the pH to 6.0 with 2.5 mol / L sodium hydroxide 0.0 part by mass, 50 parts by mass of the obtained silicon oxide-coated zinc oxide particles of Example 1 and 4.0 parts by mass of glycerin were mixed with a homodisper, and the silicon oxide-coated zinc oxide particles of Example 1 were mixed. A contained aqueous composition was obtained.

[Evaluation of Dispersibility of Silicon Oxide-Coated Zinc Oxide Particles in Aqueous Composition]
A carbomer (trade name: Carbopol Ultraz 10 polymer, manufactured by Lubrizol Advanced Materials) 1.5 g was dissolved in pure water, and then 10% by mass sodium hydroxide aqueous solution was added dropwise to pH 7 containing 1.5% by mass of carbomer. 5 carboxyvinyl polymer gel was obtained.
10 parts by mass of the aqueous composition containing silicon oxide-coated zinc oxide particles of Example 1 and 90 parts by mass of the obtained carboxyvinyl polymer gel were mixed. This liquid mixture was sandwiched between two glass slides and observed with an optical microscope.
As a result, among the observed aggregates of silicon oxide-coated zinc oxide, the maximum particle size was 20 μm. The results are shown in FIG.

[Surface wettability evaluation of silicon oxide coated zinc oxide particles]
The silicon oxide-coated zinc oxide particle-containing aqueous composition of Example 1 and decamethylcyclopentasiloxane were mixed at a mass ratio of 1: 1, and an ultrasonic washer ((W-113MK-II, manufactured by Honda Electronics Co., Ltd.). ) For 10 minutes to prepare a mixed solution, which was then allowed to stand for 20 hours.
As a result of visual observation of the liquid mixture after standing, the liquid mixture was separated into an aqueous phase and an oil phase, the aqueous phase in which the silicon oxide-coated zinc oxide particles were dispersed was cloudy, and the oil phase was transparent. It was.
The spectral transmittance of the oil phase of this mixed solution was measured with SPF analyzer UV-1000S (manufactured by Labsphere) based on decamethylcyclopentasiloxane. As a result, the transmittance at 360 nm was 100%, and it was confirmed that the silicon oxide-coated zinc oxide particles of Example 1 were in a surface state that was easy to adapt to water and difficult to adapt to oil.

[SPF evaluation of aqueous composition]
In the same manner as the evaluation of dispersibility, 10 parts by mass of the aqueous composition containing silicon oxide-coated zinc oxide particles of Example 1 and 90 parts by mass of carboxyvinyl polymer gel having a pH of 7.5 were mixed. Using this mixed liquid, a thin film was formed on a quartz substrate so as to have a thickness of 12 μm, and the spectral transmittance of the thin film was measured with SPF analyzer UV-1000S (manufactured by Labsphere). The results are shown in FIG. The SPF value was 8.2.

[Stability evaluation of viscosity of aqueous composition]
After producing the aqueous composition containing silicon oxide-coated zinc oxide particles of Example 1 (0 hour), the pH and viscosity were measured. This composition was stored at 40 ° C., and pH and viscosity were measured every predetermined time. The results are shown in Table 2 and FIG.

"Production of oil-in-water cosmetics"
79.1 parts by weight of water, 0.6 parts by weight of PEG-60 hydrogenated castor oil, and 0.3 parts by weight of alkyl-modified carboxyvinyl polymer (trade name: PEMULEN TR-1, manufactured by Lubrizol Advanced Materials) did.
Subsequently, 1.8 mol / L potassium hydroxide was mixed with this mixture, pH was adjusted to 7.0, and the gel was produced.
Next, 10.0 parts by mass of ethylhexyl methoxycinnamate was added to the resulting gel and mixed with a homodisper.
Next, 10.0 parts by mass of the silicon oxide-coated zinc oxide particle-containing aqueous composition of Example 1 was added to the obtained mixture and mixed with a homodisper to thereby add the silicon oxide-coated ultraviolet shielding particle-containing aqueous composition. Thus, an oil-in-water cosmetic of Example 1 was obtained.

[Evaluation of dispersibility of silicon oxide-coated zinc oxide particles in oil-in-water cosmetics]
"Production of artificial sebum"
An artificial sebum was prepared by mixing 5.0 parts by mass of oleic acid, 5.0 parts by mass of squalane and 5.0 parts by mass of olive oil.

"Evaluation of dispersibility"
6.5 parts by mass of the oil-in-water cosmetic of Example 1 and 2.5 parts by mass of artificial sebum were mixed. This mixture was sandwiched between two glass slides and observed with an optical microscope.
As a result, among the observed aggregates of silicon oxide-coated zinc oxide particles, the maximum particle size was 25 μm. The results are shown in FIG.

[Evaluation of UV shielding properties]
The artificial sebum produced above was applied to a helioplate (trade name: HELIOPLATE HD6, manufactured by Heliosscreen) so as to be 0.5 mg / cm ² and dried for 30 minutes.
Next, the oil-in-water cosmetic of Example 1 was applied at 1.3 mg / cm ² and dried for 15 minutes to form a coating film. The SPF value of this coating film was measured with SPF analyzer UV-1000S (manufactured by Labsphere).
As a result, the SPF value was 13.3.

[Example 2]
In Example 1, except that methyltriethoxysilane was 1.0% by mass with respect to the total mass of the zinc oxide particles (the alkyl group was 0.08% by mass in the silicon oxide-coated zinc oxide particles). In the same manner as in Example 1, silicon oxide-coated zinc oxide particles of Example 2 were obtained.
Instead of using the silicon oxide-coated zinc oxide particles of Example 1, the silicon oxide-coated zinc oxide particles of Example 2 were contained in the same manner as in Example 1 except that the silicon oxide-coated zinc oxide particles of Example 2 were used. An aqueous composition was obtained.

  The dispersibility of the silicon oxide-coated zinc oxide particles in the aqueous composition was evaluated in the same manner as in Example 1. As a result, among the observed aggregates of the silicon oxide-coated zinc oxide, the maximum particle size was 30 μm. The results are shown in FIG.

The surface wettability of the silicon oxide-coated zinc oxide particles was evaluated in the same manner as in Example 1.
As a result of visually observing the mixed solution after standing for 20 hours, the mixed solution was separated into an aqueous phase and an oil phase, the aqueous phase in which the silicon oxide-coated zinc oxide particles were dispersed was cloudy, and the oil phase was transparent Met.
Further, the spectral transmittance of the oil phase of this mixed solution was measured in the same manner as in Example 2. As a result, the transmittance at 360 nm was 100%, and it was confirmed that the silicon oxide-coated zinc oxide particles of Example 2 were in a surface state that was easy to adapt to water and difficult to adapt to oil.

  The spectral transmittance of the thin film formed using the aqueous composition was measured in the same manner as in Example 1. The results are shown in FIG. The SPF value was 6.9.

  The pH and viscosity of the aqueous composition were measured in the same manner as in Example 1. The results are shown in FIG.

[Comparative Example 1]
Example 1 and Example 1 except that methyltriethoxysilane was 0% by mass with respect to the total mass of the zinc oxide particles (the alkyl group was 0% by mass in the silicon oxide-coated zinc oxide particles). Similarly, silicon oxide-coated zinc oxide particles of Comparative Example 1 were obtained.
Instead of using the silicon oxide-coated zinc oxide particles of Example 1, the silicon oxide-coated zinc oxide particles of Comparative Example 1 were contained in the same manner as in Example 1 except that the silicon oxide-coated zinc oxide particles of Comparative Example 1 were used. An aqueous composition was obtained.

  The dispersibility of the silicon oxide-coated zinc oxide particles in the aqueous composition was evaluated in the same manner as in Example 1. As a result, among the observed aggregates of silicon oxide-coated zinc oxide, the maximum particle size was 80 μm. The results are shown in FIG.

The surface wettability of the silicon oxide-coated zinc oxide particles was evaluated in the same manner as in Example 1.
As a result of visually observing the mixed solution after standing for 20 hours, the mixed solution was separated into an aqueous phase and an oil phase, the aqueous phase in which the silicon oxide-coated zinc oxide particles were dispersed was cloudy, and the oil phase was transparent Met.
Further, the spectral transmittance of the oil phase of this mixed system was measured in the same manner as in Example 1. As a result, the transmittance at 360 nm was 100%, and it was confirmed that the silicon oxide-coated zinc oxide particles of Comparative Example 1 were in a surface state that was easy to adapt to water and difficult to adapt to oil.

  The spectral transmittance of the thin film formed using the aqueous composition was measured in the same manner as in Example 1. The results are shown in FIG. The SPF value was 3.3.

[Comparative Example 2]
In Example 1, except that methyltriethoxysilane was 3.0% by mass with respect to the total mass of the zinc oxide particles (the alkyl group was 0.25% by mass in the silicon oxide-coated zinc oxide particles). In the same manner as in Example 1, silicon oxide-coated zinc oxide particles of Comparative Example 2 were obtained.
Instead of using the silicon oxide-coated zinc oxide particles of Example 1, the silicon oxide-coated zinc oxide particles of Comparative Example 2 were contained in the same manner as in Example 1 except that the silicon oxide-coated zinc oxide particles of Comparative Example 2 were used. An aqueous composition was obtained.

  The dispersibility of the silicon oxide-coated zinc oxide particles in the aqueous composition was evaluated in the same manner as in Example 1. As a result, among the observed aggregates of the silicon oxide-coated zinc oxide, the maximum particle size was 30 μm. The results are shown in FIG.

The surface wettability of the silicon oxide-coated zinc oxide particles was evaluated in the same manner as in Example 1.
As a result of visual observation of the mixed liquid after standing for 20 hours, the mixed liquid was separated into an aqueous phase and an oil phase, the aqueous phase in which the silicon oxide-coated zinc oxide particles were dispersed was cloudy, and the oil phase was slightly It became cloudy and it was confirmed that the silicon oxide-coated ultraviolet shielding particles were also contained in the oil phase.
Further, the spectral transmittance of the oil phase of this mixed system was measured in the same manner as in Example 1. As a result, the transmittance at 360 nm was 99%, and it was confirmed that the silicon oxide-coated zinc oxide particles of Comparative Example 2 were in a surface state that was easily adapted to water and slightly adapted to oil.

  The spectral transmittance of the thin film formed using the aqueous composition was measured in the same manner as in Example 1. The results are shown in FIG. The SPF value was 6.2.

When Examples 1 and 2 are compared with Comparative Examples 1 and 2, the surface of the silicon oxide-coated zinc oxide particles is not adapted to decamethylcyclopentasiloxane, and when mixed with carboxyvinyl polymer, aggregation is suppressed. As a result, it was confirmed that the SPF value in the case of coating was improved.
Moreover, even when applied to an oil-in-water cosmetic, it was confirmed that the silicon oxide-coated zinc oxide particles were prevented from agglomerating and the SPF value was high when formed into a coating film. Since the evaluation of oil-in-water cosmetics is performed by mixing with artificial sebum or by applying onto artificial sebum, it is close to the actual usage situation. That is, it was confirmed that there is a very high possibility that an effect can be obtained even when applied to human skin.

  Even if the silicon oxide-coated ultraviolet shielding particles of the present invention are contained in water-based cosmetics by controlling the surface state of the silicon oxide-coated ultraviolet shielding particles, the desired ultraviolet shielding properties can be obtained. Therefore, the range of choice of dispersants and resins is not only applicable to water-based cosmetics and oil-in-water cosmetics, which require UV-blocking ability, but also has excellent usability. And the degree of freedom in designing and blending paints can be increased, and its industrial value is great.

Claims (5)

The surface of the ultraviolet shielding particle is a silicon oxide-coated ultraviolet shielding particle coated with a silicon oxide film,
46.0 parts by mass of gel prepared by mixing water and 0.2 parts by mass of an alkyl-modified carboxyvinyl polymer and adjusting the pH to 6.0 with 2.5 mol / L sodium hydroxide, 50 parts by mass of the silicon oxide-coated ultraviolet shielding particles A mixture prepared by mixing 4.0 parts by mass of glycerin and decamethylcyclopentasiloxane at a mass ratio of 1: 1, and dispersing and treating with ultrasound for 10 minutes was allowed to stand for 20 hours. Then, the 360 nm transmittance of the oil phase of the mixed solution is 100%,
10 parts by mass of the composition and 90 parts by mass of carboxyvinyl polymer gel (pH 7.5 aqueous solution containing 1.5% by mass of carboxyvinyl polymer) are mixed, and the mixture is sandwiched between glass slides. A silicon oxide-coated ultraviolet shielding particle, wherein the particle diameter of the aggregate observed when observed is 50 μm or less.   2. The silicon oxide-coated ultraviolet shielding particles according to claim 1, wherein the content of the ultraviolet shielding particles is 50% by mass or more and 90% by mass or less.   3. A silicon oxide-coated ultraviolet shielding particle-containing aqueous composition comprising the silicon oxide-coated ultraviolet shielding particles according to claim 1 or 2 and water.   It contains at least one of the silicon oxide-coated ultraviolet shielding particles according to claim 1 or 2 and the aqueous composition containing the silicon oxide-coated ultraviolet shielding particles according to claim 3, and a cosmetic base material. Cosmetics.   An oil-in-water type comprising at least one of the silicon oxide-coated ultraviolet shielding particles according to claim 1 and the aqueous composition containing the silicon oxide-coated ultraviolet shielding particles according to claim 3 in an aqueous phase. Cosmetics.