JP6485416B2 - Silicon oxide-coated zinc oxide-containing aqueous composition and oil-in-water cosmetic - Google Patents

Description

  The present invention relates to a silicon oxide-coated zinc oxide-containing aqueous composition and an oil-in-water cosmetic.

  Cosmetics imparted with an ultraviolet shielding function are frequently used not only for leisure purposes but also on a daily basis. Therefore, emphasis is placed on cosmetics that do not feel stress so that they 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.

Water-based cosmetics are less sticky than oil-based cosmetics and provide a smooth feeling of use. In recent years, various oil-in-water (O / W) types such as sunscreens, emulsions, and creams have been obtained. Used as a cosmetic.
In order to obtain such a fresh feeling of use, a refreshing feeling, a refreshing feeling and the like, an oil-in-water gel cosmetic is preferred. Therefore, water-soluble polymers such as carboxyvinyl polymers, alkyl-modified carboxyvinyl polymers, alkyl acrylate / methacrylic acid / polyoxyethylene copolymers are widely used as thickeners to obtain gel-like cosmetics. .

However, when zinc oxide is used in these oil-in-water cosmetics, the eluted zinc ions react with water-soluble polymers such as organic UV screening agents and thickeners, resulting in performance as cosmetics. Problems such as reduction, discoloration, increase / decrease in viscosity, fluctuation in hydrogen ion index (pH), etc. may occur. Therefore, oil-in-water cosmetics using zinc oxide have limited freedom of formulation.
For example, when a water-soluble polymer such as carboxyvinyl polymer, alkyl-modified carboxyvinyl polymer, alkyl acrylate / methacrylic acid / polyoxyethylene copolymer, and zinc oxide are used in an aqueous phase, the eluted zinc ions and carboxylate When the group (COO ⁻ ) reacts, the gel structure of the polymer is destroyed and the viscosity may be lowered. For this reason, zinc oxide cannot be blended in the water phase, and must be blended in the oil phase to make a cosmetic.

  In addition, water-soluble polymers such as carboxyvinyl polymer, alkyl-modified carboxyvinyl polymer, alkyl acrylate / methacrylic acid / polyoxyethylene copolymer, and the like react with a surfactant to destroy the gel structure of the polymer. In some cases, the viscosity decreased. Therefore, even if zinc oxide can be dispersed in water using a surfactant, water-soluble polymers such as carboxyvinyl polymer, alkyl-modified carboxyvinyl polymer, alkyl acrylate / methacrylic acid / polyoxyethylene copolymer are used. It could not be included in the prescribed formula.

  As a result, in oil-in-water cosmetics, in order to obtain a sufficient UV shielding function, the amount of oil phase must be increased, so even oil-in-water cosmetics have a fresh feeling of use and refreshment, A good feeling such as a refreshing feeling was not obtained. That is, when zinc oxide is used, there is a problem that an oil-in-water type water-based cosmetic excellent in ultraviolet shielding effect and feeling of use cannot be obtained.

  In order to solve such problems of zinc oxide, silicon oxide-coated zinc oxide in which the surface of zinc oxide is coated with a dense silicon oxide film and the elution of zinc ions is suppressed has been proposed (for example, , See Patent Document 1).

International Publication No. 2014/171322

  However, when an oil-in-water emulsion is prepared using the silicon oxide-coated zinc oxide-containing aqueous composition of Patent Document 1, the dispersion stability of the aqueous composition may be poor, and there is a problem that handling is difficult. there were.

  The present invention has been made in view of the above circumstances, and an object thereof is to provide a silicon oxide-coated zinc oxide-containing aqueous composition excellent in dispersion stability and an oil-in-water cosmetic containing the same.

  As a result of intensive studies to solve the above-mentioned problems, the present inventors have adjusted the zinc ion concentration to 30 ppm or less, whereby a silicon oxide-coated zinc oxide-containing aqueous system in which silicon oxide-coated zinc oxide is stably dispersed The present inventors have found that a composition can be obtained and have completed the present invention.

That is, the silicon oxide-coated zinc oxide containing aqueous compositions of the present invention, water, a water-soluble vinyl polymers, containing, and silicon oxide-coated zinc oxide, zinc ion concentration Ri der below 30 ppm, the silicon oxide The mass percentage of the alkali metal contained in the silicon oxide film in the coated zinc oxide is 0.0001% by mass or more and 0.8% by mass or less, and Mg contained in the silicon oxide film in the silicon oxide-coated zinc oxide, mass percentage of at least one of total selected from the group consisting of Ca and Ba is characterized der Rukoto 0.01 mass% or more and 1 mass%.

  The oil-in-water cosmetic of the present invention is characterized by containing the silicon oxide-coated zinc oxide-containing aqueous composition of the present invention in an aqueous phase.

  According to the silicon oxide-coated zinc oxide-containing aqueous composition of the present invention, since the silicon oxide-coated zinc oxide is stably dispersed, an aqueous composition having an excellent ultraviolet shielding effect and feeling of use can be obtained.

  According to the oil-in-water cosmetic of the present invention, since the aqueous phase contains the silicon oxide-coated zinc oxide-containing aqueous composition of the present invention, it is possible to obtain a cosmetic excellent in ultraviolet shielding effect and feeling of use. it can.

In Example 2 and Example 5, it is a graph which shows the measurement result of the transmittance | permeability of a silicon oxide covering zinc oxide containing aqueous composition. In Example 2 and Example 5, it is a graph which shows the measurement result of the SPF value of a silicon oxide covering zinc oxide containing aqueous composition. In Example 3, Example 6, and Comparative Example 2, it is a graph which shows the measurement result of the viscosity of a silicon oxide covering zinc oxide containing aqueous composition. In an experimental example, it is a graph which shows the relationship between a zinc ion concentration and the viscosity of a carbomer gel.

A preferred embodiment for carrying out the silicon oxide-coated zinc oxide-containing aqueous composition of the present invention and the oil-in-water cosmetic containing the same 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 zinc oxide-containing aqueous composition]
The silicon oxide-coated zinc oxide-containing aqueous composition of the present embodiment is a composition containing water, a water-soluble vinyl polymer, and silicon oxide-coated zinc oxide, and having a zinc ion concentration of 30 ppm or less.
The silicon oxide-coated zinc oxide-containing composition of the present embodiment may be in a liquid form or a gel form.
The zinc ion concentration is preferably low, preferably 20 ppm or less, more preferably 15 ppm or less, and even more preferably 10 ppm or less.

  In the silicon oxide-coated zinc oxide-containing aqueous composition of this embodiment, a dispersant, a stabilizer, a water-soluble binder, a thickener, an alcohol, a chelating agent, and the like are generally used in aqueous cosmetics as necessary. An additive may be included.

In the silicon oxide-coated zinc oxide-containing aqueous composition of the present embodiment, the content of the water-soluble vinyl polymer with respect to 100 parts by mass of the silicon oxide-coated zinc oxide is 0.02 parts by mass or more and 6.0 parts by mass or less. Preferably, it is 0.1 to 5.0 parts by mass, more preferably 0.2 to 4.5 parts by mass.
When the content of the water-soluble vinyl polymer with respect to 100 parts by mass of silicon oxide-coated zinc oxide 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 zinc oxide is 6.0 parts by mass or less, the viscosity is in an appropriate range and stirring is easy, so that a uniform composition is obtained. It is done.

In the silicon oxide-coated zinc oxide-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% by mass. % Or more and 0.75% by mass or less, more preferably 0.1% by mass or more and 0.5% by mass or less.
In the silicon oxide-coated zinc oxide-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 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.
Among these water-soluble vinyl polymers, it is more preferable to use an alkyl-modified carboxyvinyl polymer. Alkyl-modified carboxyvinyl polymers are the same components as thickeners even if they are added to water-based cosmetics or oil-in-water cosmetics thickened with carboxyvinyl polymers or alkyl-modified carboxyvinyl polymers. There is little influence on viscosity and other ingredients, and a cosmetic can be easily produced.

  In order to improve the dispersibility of the water-soluble vinyl polymer and the silicon oxide-coated zinc oxide in water, the silicon oxide-coated zinc oxide-containing aqueous composition of the present embodiment preferably contains an alcohol.

In the silicon oxide-coated zinc oxide-containing aqueous composition of the present embodiment, the content of alcohols with respect to 100 parts by mass of silicon oxide-coated zinc oxide is preferably 10 parts by mass or more and 100 parts by mass or less, and 20 parts by mass or more and More preferably, it is 50 parts by mass or less.
If content of alcohol with respect to 100 mass parts of silicon oxide coating zinc oxides is 10 mass parts or more, the dispersibility of silicon oxide coating zinc oxide can be improved more. On the other hand, if the content of alcohols is 100 parts by mass or less with respect to 100 parts by mass of silicon oxide-coated zinc oxide, the stickiness and feel when the silicon oxide-coated zinc oxide-containing aqueous composition of the present embodiment is blended in cosmetics. Deterioration can be suppressed.

  In the silicon oxide-coated zinc oxide-containing aqueous composition of the present embodiment, the alcohol content is preferably 0.1% by mass or more and 30% by mass or less, and 0.3% by mass or more and 25% by mass. % Or less, more preferably 0.5% by mass or more and 20% by mass or less.

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, C1-C6 monohydric alcohols or polyhydric alcohols 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.

The silicon oxide-coated zinc oxide-containing aqueous composition of the present embodiment has a zinc ion concentration of 30 ppm or less, preferably 25 ppm or less, more preferably 20 ppm or less, and further preferably 15 ppm or less.
When the zinc ion concentration exceeds 30 ppm, a silicon oxide-coated zinc oxide-containing aqueous composition in which silicon oxide-coated zinc oxide is stably dispersed cannot be obtained.

  As a measuring method of the zinc ion concentration in the silicon oxide-coated zinc oxide-containing aqueous composition of the present embodiment, for example, an analysis method using Inductively Coupled Plasma Atomic Emission Spectroscopy (ICP-AES) Is mentioned.

The silicon oxide-coated zinc oxide-containing aqueous composition of the present embodiment has a viscosity of 0.1 Pa · s or more and 15 Pa when measured at 20 ° C. and 30 rotations (rpm) using a BII type rotational viscometer. It is preferably s or less, more preferably 0.2 Pa · s or more and 13 Pa · s or less, and further preferably 0.3 Pa · s or more and 10 Pa · s or less.
When the viscosity of the silicon oxide-coated zinc oxide-containing aqueous composition is within the above range, the silicon oxide-coated zinc oxide-containing aqueous composition can be suitably used for oil-in-water cosmetics.

Further, the silicon oxide-coated zinc oxide-containing aqueous composition of the present embodiment preferably has a viscosity of 0.1 Pa · s or more and 15 Pa · s or less after storage at 40 ° C. for 1 month, More preferably, it is s or more and 13 Pa · s or less, and further preferably 0.3 Pa · s or more and 10 Pa · s or less.
Even when stored at 40 ° C. for one month, the viscosity of the silicon oxide-coated zinc oxide-containing aqueous composition is preferably within the above range, so that the performance as an aqueous cosmetic can be maintained.

The silicon oxide-coated zinc oxide-containing aqueous composition of the present embodiment preferably has a hydrogen ion index (pH) of 6.0 or more and 9.0 or less, and is 6.5 or more and 9.0 or less. More preferably, it is 7.0 or more and 9.0 or less.
When the pH is within the above range, it can be suitably used for oil-in-water type water-based cosmetics.

In addition, the silicon oxide-coated zinc oxide-containing aqueous composition of the present embodiment preferably has a hydrogen ion index (pH) of 6.0 or more and 9.0 or less after storage at 40 ° C. for 1 month. More preferably, it is 0.5 or more and 9.0 or less, and more preferably 7.0 or more and 9.0 or less.
Even if it is stored at 40 ° C. for 1 month, it is preferable that the hydrogen ion index is within the above range, so that the performance that can be used as the hydrogen ion index of cosmetics can be maintained.

The silicon oxide-coated zinc oxide-containing aqueous composition of the present embodiment has a viscosity when stored under accelerated conditions, for example, when stored at 40 ° C. and measured after one month has elapsed. The viscosity after reduction in viscosity under the initial conditions, for example, the value divided by the viscosity measured after 720 hours at 40 ° C. is preferably 0.7 or more and 1.0 or less.
As described above, the value obtained by dividing the viscosity under accelerated conditions, that is, after one month has passed, by the viscosity after decreasing the viscosity under the initial conditions is within the above range, whereby the silicon oxide of this embodiment The viscosity of the coated zinc oxide-containing aqueous composition can be maintained over a medium to long period. The silicon oxide-coated zinc oxide-containing aqueous composition as described above can be obtained by controlling (adjusting) the conditions described in this specification.

  The silicon oxide-coated zinc oxide-containing aqueous composition of the present embodiment is diluted with alcohols as necessary, so that the content of silicon oxide-coated zinc oxide in the silicon oxide-coated zinc oxide-containing aqueous composition is 5% by mass. When a thin film (silicon oxide-coated zinc oxide-containing aqueous composition) having a thickness of 12 μm is formed using a material, the transmittance of the thin film with respect to light having a wavelength of 450 nm is preferably 40% or more, and 50% or more. More preferably, it is more preferably 60% or more. The transmittance is obtained by forming a silicon oxide-coated zinc oxide-containing aqueous composition containing 5% by mass of silicon oxide-coated zinc oxide on a quartz substrate to a thickness of 12 μm, and measuring the spectral transmittance of the thin film with an SPF analyzer. It can obtain | require by measuring in UV-1000S (made by Labsphere).

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 silicon oxide-coated zinc oxide-containing aqueous composition is appropriately adjusted according to desired characteristics. From the viewpoint of improving the usability of the silicon oxide-coated zinc oxide-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. Is more preferably 40% by mass or more and 94% by mass or less.

  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.

When an alkyl-modified carboxyvinyl polymer is used as the water-soluble vinyl polymer, the content of the alkyl-modified carboxyvinyl polymer in 100 parts by mass of the silicon oxide-coated zinc oxide in the silicon oxide-coated zinc oxide-containing aqueous composition of the present embodiment is It is preferably 0.02 parts by mass or more and 2.0 parts by mass or less, more preferably 0.1 parts by mass or more and 1.5 parts by mass or less, and 0.2 parts by mass or more and 1.0 parts by mass. More preferably, it is at most parts.
When the content of the alkyl-modified carboxyvinyl polymer with respect to 100 parts by mass of silicon oxide-coated zinc oxide is 0.02 parts by mass or more, dispersion stability can be secured and a uniform composition can be obtained. On the other hand, when the content of the alkyl-modified carboxyvinyl polymer with respect to 100 parts by mass of the silicon oxide-coated zinc oxide is 2.0 parts by mass or less, the viscosity becomes an appropriate range and stirring is easy, so that a uniform composition can be obtained. It is done.

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, as an alkyl acrylate / methacrylic acid / polyoxyethylene copolymer, Aculine (registered trademark) 22, Aculin (registered trademark) 28, and Aculin (registered trademark) 88 commercially available from Rohm & Haas are also used. Good.
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.

The silicon oxide-coated zinc oxide is not particularly limited as long as it can suppress increase / decrease in viscosity and fluctuation in pH when mixed with water to form an aqueous composition.
As such a silicon oxide-coated zinc oxide, the surface of zinc oxide particles is coated with a silicon oxide film, and the silicon oxide film is dense, or an alkali metal remaining in the silicon oxide-coated zinc oxide. Is preferably substituted with at least one selected from the group consisting of Mg, Ca and Ba.

  The content of the silicon oxide-coated zinc oxide in the silicon oxide-coated zinc oxide-containing aqueous composition of the present embodiment is appropriately adjusted according to desired properties. From the viewpoint of transparency and ultraviolet shielding property, the content of the silicon oxide-coated zinc oxide is preferably 1% by mass or more and 80% by mass or less, more preferably 5% by mass or more and 70% by mass or less. The content is more preferably 10% by mass or more and 70% by mass or less, and most preferably 20% by mass or more and 65% by mass or less.

The silicon oxide-coated zinc oxide-containing aqueous composition of the present embodiment preferably has an SPF value of 5 or more when the content of the silicon oxide-coated zinc oxide of the present embodiment is 5% by mass.
When the content of silicon oxide-coated zinc oxide is 5% by mass and the SPF value of the silicon oxide-coated zinc oxide-containing aqueous composition is 5 or more, an ultraviolet shielding effect is imparted to the oil-in-water cosmetic. be able to.

Further, the silicon oxide-coated zinc oxide-containing aqueous composition of the present embodiment preferably has an SPF value of 15 or more when the silicon oxide-coated zinc oxide-containing content of the present embodiment is 7% by mass. .
When the content of the silicon oxide-coated zinc oxide is 7% by mass and the SPF value of the silicon oxide-coated zinc oxide-containing aqueous composition is 15 or more, an ultraviolet shielding effect is imparted to the oil-in-water cosmetic. be able to.

In addition, the silicon oxide-coated zinc oxide-containing aqueous composition of this embodiment has an SPF value of 25 or more when the content of the silicon oxide-coated zinc oxide of this embodiment is 10% by mass in terms of zinc oxide. Is more preferable.
When the content of the silicon oxide-coated zinc oxide is 10% by mass and the SPF value of the silicon oxide-coated zinc oxide-containing aqueous composition is 25 or more, an ultraviolet shielding effect is imparted to the oil-in-water cosmetic. be able to.

(Example 1 of silicon oxide-coated zinc oxide)
An example of a silicon oxide film is dense silicon oxide-coated zinc oxide, a silicon oxide-coated zinc oxide formed by the surface of the zinc oxide particles coated with silicon oxide film, the Q ³ environments of silicon oxide, silicon in the film Silicon oxide-coated zinc oxide in which Q ³ + Q ⁴ ≧ 0.6 and Q ⁴ / (Q ³ + Q ⁴ ) ≧ 0.5 when the abundance ratio is Q ³ and the abundance ratio in the Q ⁴ environment is Q ⁴ is mentioned. It is done. Furthermore, it is preferable that the silicon oxide film is uniformly coated on the entire zinc oxide particles such that the degradation rate of brilliant blue generated by the photocatalytic activity of the zinc oxide particles is 3% or less.

The silicon oxide film is, when the ^{Q 4} abundance ratio of the presence ratio in ^Q 3, ^{Q 4} environment in ^{Q 3} Environment ^{"silicon, Q} 3 + Q ⁴ ≧ 0.6 and ^{Q 4 / (Q 3 + Q} 4) ≧ The higher the degree of condensation, the higher the degree of condensation.
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.

Regarding the degree of condensation of silicon oxide, a silicon oxide-coated zinc oxide was measured for its NMR spectrum by solid ²⁹ Si MAS-nuclear magnetic resonance (NMR) spectroscopy. From the peak area ratio of this NMR spectrum, Q ⁰ , Q ¹ , Q ² , Q ³ , and Q ⁴ can be easily known by measuring the area ratio of signals attributed to each environment.
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 zinc oxide 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 zinc oxide particles is suppressed, so that the homogeneity of the silicon oxide film covering the zinc oxide particles is also high. Because it means. Here, the high homogeneity of the silicon oxide film covering the zinc oxide particles indicates 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 zinc oxide particles. The photocatalytic reaction of zinc oxide particles basically occurs on the surface of the zinc oxide particles. That is, the low decomposition rate of brilliant blue generated by the photocatalytic activity of zinc oxide particles indicates that there are few exposed portions of zinc oxide particles on the surface of silicon oxide-coated zinc oxide.

The method for measuring the degradation rate of brilliant blue is as follows.
First, a brilliant blue aqueous solution in which brilliant blue is adjusted to a predetermined content (for example, 5 ppm) is prepared. A silicon oxide-coated zinc oxide having a mass of 1% by mass of this liquid is 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).
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) (where 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 spectrum of the supernatant. The absorbance at the absorption maximum wavelength of.

  In addition, about normal zinc oxide (average particle diameter 35nm; made by Sumitomo Osaka Cement Co., Ltd.), it was 90% as a result of measuring the decomposition rate of brilliant blue based on said method. Thereby, it was confirmed that this zinc oxide (average particle size 35 nm; manufactured by Sumitomo Osaka Cement Co., Ltd.) has a high decomposition rate of brilliant blue when it has photocatalytic activity.

  The average particle diameter of the silicon oxide-coated zinc oxide is preferably 3 nm or more and 2 μm or less. In order for the silicon oxide-coated zinc oxide-containing aqueous composition to obtain desired transparency and ultraviolet shielding property, the above range is satisfied. Adjust as appropriate. When it is desired to obtain a highly transparent silicon oxide-coated zinc oxide-containing aqueous composition, the average particle size of the silicon oxide-coated zinc oxide 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 of the silicon oxide-coated zinc oxide-containing aqueous composition, the average particle size of the silicon oxide-coated zinc oxide is preferably 50 nm or more and 2 μm or less.

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

  The content of zinc oxide particles in the silicon oxide-coated zinc oxide is preferably 50% by mass to 90% by mass. Here, if the content of the zinc oxide particles in the silicon oxide-coated zinc oxide is less than 50% by mass, a desired ultraviolet shielding effect cannot be obtained. Therefore, it is not preferable to obtain a desired ultraviolet shielding effect because a large amount of silicon oxide-coated zinc oxide must be used. On the other hand, if the content of the zinc oxide particles in the silicon oxide-coated zinc oxide exceeds 90% by mass, the ratio of the zinc oxide particles in the silicon oxide-coated zinc oxide becomes too high. Is not preferable because it cannot be covered sufficiently.

When the silicon oxide-coated zinc oxide is 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 zinc eluted in the aqueous solution is preferably 60% by mass or less, The content is more preferably 20% by mass or less, and further preferably 10% by mass or less.
Here, the reason why it is preferable that the zinc elution rate is 60% by mass or less is that if the zinc elution rate exceeds 60% by mass, the stability of the silicon oxide-coated zinc oxide itself decreases, and the silicon oxide coating When zinc oxide is applied to cosmetics, the eluted zinc ions react with water-soluble polymers such as organic UV-screening agents and thickeners, resulting in deterioration in cosmetic performance, discoloration, and increase / decrease in viscosity. This is because it is not preferable.

The elution rate of zinc is, for example, by dispersing silicon oxide-coated zinc oxide 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, and the zinc concentration in the liquid phase Can be measured by measuring with an ICP emission spectrometer.
The buffer solution having pH = 5 is not particularly limited as long as it can disperse silicon oxide-coated zinc oxide. For example, 500 ml of 0.1 M potassium hydrogen phthalate aqueous solution and 0.1 M sodium hydroxide aqueous solution A buffer solution with a total volume of 1000 ml by adding water after mixing with 226 ml is preferably used.

  The average particle diameter of the zinc oxide particles is appropriately adjusted in order for the silicon oxide-coated zinc oxide-containing aqueous composition to obtain desired transparency and ultraviolet shielding properties. When it is desired to obtain a highly transparent silicon oxide-coated zinc oxide-containing aqueous composition, the average particle diameter of the zinc oxide 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 of the silicon oxide-coated zinc oxide-containing aqueous composition, the average particle diameter of the zinc oxide particles is preferably 50 nm or more and 500 nm or less.

A method for producing such silicon oxide-coated zinc oxide 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 zinc oxide using alkoxysilane, or sodium silicate and alkoxysilane, and fired at 200 ° C. to 600 ° C. A silicon oxide-coated zinc oxide is obtained.
In addition, when using a zinc oxide particle with an average particle diameter of 50 nm or more, you may bake at 150 to 600 degreeC.

(Example 2 of silicon oxide-coated zinc oxide)
Another example of the silicon oxide-coated zinc oxide is silicon oxide-coated zinc oxide obtained by coating the surface of zinc oxide particles with a silicon oxide film, and is at least one selected from the group consisting of Mg, Ca and Ba And silicon oxide-coated zinc oxide containing The reason why it is preferable to use this silicon oxide-coated zinc oxide is as follows.

  In order to uniformly coat the entire surface of the zinc oxide particles with a silica coating so that the decomposition rate of the brilliant blue generated by the photocatalytic activity of the zinc oxide 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 this alkali metal remains in the silicon oxide-coated zinc oxide, the alkali ions are eluted when the silicon oxide-coated zinc oxide is dispersed in the aqueous phase, causing the pH and viscosity to fluctuate greatly. As a result, the stability of quality is impaired.

Therefore, by replacing the alkali metal contained in the silicon oxide film of the silicon oxide-coated zinc oxide with at least one selected from the group consisting of Mg, Ca and Ba, the silicon oxide film of the silicon oxide-coated zinc oxide The alkali metal contained therein is removed from the silicon oxide film of the silicon oxide-coated zinc oxide.
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 zinc oxide 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 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 zinc oxide is the mass of the alkali metal contained in the silicon oxide film. Greater than percentage. Therefore, even when this silicon oxide-coated zinc oxide is mixed with the aqueous phase, the elution of alkali metal is suppressed, fluctuations in pH and viscosity can be suppressed, and quality stability as a cosmetic can be maintained. .

  The average particle diameter of the silicon oxide-coated zinc oxide is selected as necessary, but is preferably 2 nm or more and 2 μm or less, more preferably 5 nm or more and 500 nm or less, and more preferably 10 nm or more and 400 nm or less. More preferably.

  The smaller the average particle diameter of the silicon oxide-coated zinc oxide is, the more suitable it is for increasing transparency when used in cosmetics. On the other hand, the larger the average particle diameter of the silicon oxide-coated zinc oxide is, the higher the ultraviolet light scattering intensity is, and it is possible to shield the ultraviolet light up to a long wavelength. Therefore, the average particle diameter of the silicon oxide-coated zinc oxide is appropriately selected according to the transparency of the target cosmetic and the ultraviolet shielding property.

The content of zinc oxide particles in the silicon oxide-coated zinc oxide is selected as necessary, but is preferably 50% by mass or more and 99% by mass or less, and 70% by mass or more and 95% by mass or less. Is more preferably 70% by mass or more and 90% by mass or less.
Here, if the content of the zinc oxide particles in the silicon oxide-coated zinc oxide is less than 50% by mass, a desired ultraviolet shielding effect may not be obtained. In a cosmetic containing such a silicon oxide-coated zinc oxide in the base, it is not preferable to obtain a desired ultraviolet shielding effect because a large amount of silicon oxide-coated zinc oxide must be used.
On the other hand, when the content of the zinc oxide particles in the silicon oxide-coated zinc oxide exceeds 99% by mass, the ratio of the zinc oxide particles in the silicon oxide-coated zinc oxide may become too high. As a result, the surface of the zinc oxide particles cannot be sufficiently covered with the silicon oxide film, and the photocatalytic activity of zinc oxide and elution suppression of zinc ions may be insufficient, which is not preferable.

  The content of silicon oxide in the silicon oxide-coated zinc oxide is appropriately adjusted according to the average particle diameter of the zinc oxide particles. For example, regarding zinc oxide particles having an average particle diameter of 50 nm or less, the content of silicon oxide is preferably 3% by mass or more and 45% by mass or less. For zinc oxide particles having an average particle diameter exceeding 50 nm, the content of silicon oxide is preferably 1% by mass or more and 35% by mass or less.

The silicon oxide-coated zinc oxide contains at least one selected from the group consisting of Mg, Ca, and Ba.
In the silicon oxide-coated zinc oxide, 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. It is preferable that 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 what is generally known, and specifically means at least one selected from the group consisting of lithium, sodium, potassium, rubidium, cesium, and francium. .

  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. This is because, in the initial stage of silicon oxide-coated zinc oxide, the fluctuation factor of the hydrogen ion index (pH) is not the elution of zinc ions but the elution of alkali metal ions contained in the silicon oxide film.

The mass percentage of the alkali metal contained in the silicon oxide film in the silicon oxide-coated zinc oxide 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 as follows.
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%, 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 zinc oxide is 0.01% by mass or more and 1% by mass or less. preferable.

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

In silicon oxide-coated zinc oxide, the decomposition rate of brilliant blue generated by the photocatalytic activity of zinc oxide particles is preferably 3% or less, more preferably 2% or less, and even more preferably 1% or less.
Further, a silicon oxide film of silicon oxide-coated zinc oxide, "when the abundance ratio of the presence ratio in ^{Q 3} environments of silicon in ^Q 3, ^{Q 4} environment was ^{Q 4, Q 3 + Q 4} ≧ 0.6 and ^{Q 4} / (Q ³ + Q ⁴ ) ≧ 0.5 ”is preferable.

[Method for producing silicon oxide-coated zinc oxide]
A method for producing the silicon oxide-coated zinc oxide in this embodiment will be described.
The method for producing silicon oxide-coated zinc oxide in the present embodiment is at least one selected from the group consisting of composite particles obtained by coating the surface of zinc oxide particles with silicon oxide containing an alkali metal, and Mg, Ca, and Ba. A step of mixing seeds in a solution containing water, 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”). And a baking step.

In addition, the zinc oxide which coat | covers the silicon oxide containing the alkali metal before a substitution process, or the silicon oxide covering zinc oxide 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 alkoxysilane and oligomers of 10-mer or less alkoxysilane, a catalyst, and water are added, and the mixture is allowed to react for 30 minutes or more and 24 hours or less, and the degree of condensation is increased. A step of forming a high silicon oxide film may be provided.
Next, a method for producing silicon oxide-coated zinc oxide will be described in detail.

As zinc oxide formed by coating silicon oxide containing alkali metal, silicate containing alkali metal such as sodium silicate and zinc oxide particles are reacted to form silicon oxide on the surface of zinc oxide particles. You may use what coat | covered. Alternatively, commercially available zinc oxide coated with silicon oxide may be used.
Examples of the method for coating the surface of zinc oxide particles with silicon oxide include, for example, JP-A-03-183620, JP-A-11-256133, JP-A-11-303015, JP-A-2007-016111, and the like. The methods described can be used.

The method of coating the surface of the zinc oxide particles with silicon oxide is selected as necessary, and examples thereof include the following methods.
First, zinc oxide particles and water are mixed, and then the zinc oxide particles are ultrasonically dispersed in water to prepare a zinc oxide aqueous suspension.
Next, the aqueous zinc oxide suspension is heated, and while stirring the aqueous zinc oxide suspension, an aqueous sodium silicate solution is added and aged for 10 to 60 minutes.
Next, while stirring the zinc oxide aqueous suspension, an acid such as dilute sulfuric acid is added to adjust the pH to 5 to 9, and the mixture is aged 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. Zinc oxide particles are obtained.

"Replacement process"
The replacement step needs to be performed after the step of coating the surface of the zinc oxide 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 zinc oxide particles with silicon oxide by the neutralization reaction of silicate to the step after the drying step. . According to such a method, the reaction process can be reduced, and the silicon oxide-coated zinc oxide in the present embodiment can be obtained at low cost.

In the substitution step, first, zinc oxide covered 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. .
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 to be more than the freezing point of the solvent in the liquid mixture containing zinc oxide coated with silicon oxide, at least one selected from the group consisting of Mg, Ca and Ba, and a 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 zinc oxide coated with silicon oxide is replaced with at least one selected from the group consisting of Mg, Ca and Ba, and mixed from the zinc oxide coated with silicon oxide. Elutes in the liquid. 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 zinc oxide by substitution with an alkali metal, and as a result, from Mg, Ca and Ba The silicon oxide-coated zinc oxide contains 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 zinc oxide coated with silicon oxide with at least one ion selected from the group consisting of Mg, Ca and Ba, it is included in the mixed solution The content of at least one selected from the group consisting of Mg, Ca, and Ba is preferably not less than the sum of molar equivalents of alkali metals in zinc oxide 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.

Next, the liquid mixture containing the silicon oxide-coated zinc oxide produced by this substitution step is subjected to solid-liquid separation by atmospheric pressure filtration, vacuum filtration, pressure filtration, centrifugation, or the like. The obtained solid is washed with a solvent such as water to obtain silicon oxide-coated zinc oxide.
In order to further reduce the content of the alkali metal in the obtained silicon oxide-coated zinc oxide, after the solid-liquid separation, again the obtained silicon oxide-coated zinc oxide and the group consisting of Mg, Ca and Ba And at least one selected from the group consisting of an alkali metal in the silicon oxide-coated zinc oxide and at least one selected from the group consisting of Mg, Ca and Ba It is preferable to carry out. More preferably, this replacement step is repeated a plurality of times.

Since the silicon oxide-coated zinc oxide thus obtained contains water, it is preferably dried to remove this water.
The drying temperature is not particularly limited, but it is usually preferable to dry 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.

  Next, the silicon oxide-coated zinc oxide in this embodiment can be produced by performing a heat treatment (baking) on the dried product at 200 ° C. or more and less than 600 ° C.

  The average dispersed particle size of the silicon oxide-coated zinc oxide in the silicon oxide-coated zinc oxide-containing aqueous composition 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, More preferably, it is 25 nm or more and 500 nm or less. When the average dispersed particle diameter of the silicon oxide-coated zinc oxide is less than 10 nm, the crystallinity of the silicon oxide-coated zinc oxide is lowered, and as a result, sufficient ultraviolet shielding properties may not be exhibited. On the other hand, if the average dispersed particle size of the silicon oxide-coated zinc oxide exceeds 2 μm, glare, creaking, etc. may occur, and the feeling of use when formulated into a cosmetic may be worsened, and the dispersion stability is reduced. However, a stable composition may not be obtained. In the present invention, the dispersed particle diameter means a particle diameter in a state where a plurality of silicon oxide-coated zinc oxide particles are gathered and dispersed.

[Method for producing silicon oxide-coated zinc oxide-containing aqueous composition]
As a method for producing the silicon oxide-coated zinc oxide-containing aqueous composition of the present embodiment, a water-soluble vinyl polymer, water, and silicon oxide-coated zinc oxide are mixed with low energy so as not to elute zinc ions, A method of uniformly dispersing these components is used.
As a method of mixing at low energy, a method using a homodisper is preferable.
According to this method, an aqueous composition in which a water-soluble vinyl polymer, water, and silicon oxide-coated zinc oxide are uniformly mixed and zinc ion elution is reduced can be produced.

Before mixing the water-soluble vinyl polymer with the silicon oxide-coated zinc oxide, water and a pH adjuster such as sodium hydroxide are added as appropriate so that the hydrogen ion index (pH) is 4.0 to 8.5. It is preferably adjusted to 4.5, more preferably 4.5 to 8.0, and even more preferably 5.0 to 7.5.
The pH adjuster is not particularly limited as long as it can be used in cosmetics. Examples of the pH adjuster include sodium hydroxide.

  Since the viscosity of the silicon oxide-coated zinc oxide-containing aqueous composition of the present embodiment can be adjusted by the content of the water-soluble vinyl polymer, the viscosity may be appropriately adjusted and mixed so as to obtain a desired viscosity.

[Oil-in-water cosmetics]
The oil-in-water cosmetic of this embodiment contains the silicon oxide-coated zinc oxide-containing aqueous composition of this embodiment in the aqueous phase.

The oil-in-water cosmetic of the present embodiment is an oil-in-water emulsion containing the silicon oxide-coated zinc oxide-containing aqueous composition of the present embodiment in an aqueous phase, and an oil component contained in the oil phase.
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 and used.
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 are improved, and the sustainability of these effects is improved.

  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. . 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 the content of the chelating agent is less than 0.01% by mass, the desired properties cannot be obtained in the oil-in-water cosmetic, which is not preferable. On the other hand, when the content of the chelating agent exceeds 1.0% by mass, an oil-in-water cosmetic cannot be used as a cosmetic from the viewpoint of safety, which is not preferable. For example, the amount of ethylenediaminetetraacetic acid (EDTA) in cosmetics is regulated to 1.0% 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 the like. 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 zinc oxide 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 More preferably, it is 500 nm or less. When the average dispersed particle diameter of the silicon oxide-coated zinc oxide is less than 10 nm, the crystallinity of the silicon oxide-coated zinc oxide is lowered, and as a result, sufficient ultraviolet shielding properties may not be exhibited. On the other hand, if the average dispersed particle size of the silicon oxide-coated zinc oxide exceeds 2 μm, glare, creaking, etc. may occur and the feeling of use may be deteriorated, and the dispersion stability may be lowered, resulting in a stable oil-in-water type. May not be available. In the present invention, the dispersed particle diameter means a particle diameter in a state where a plurality of silicon oxide-coated zinc oxide particles are gathered and dispersed.

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.

[Method for producing oil-in-water cosmetics]
The method for producing an oil-in-water cosmetic of the present embodiment includes an oil-in-water type (O / O) in which the silicon oxide-coated zinc oxide-containing aqueous composition of the present embodiment is contained in an aqueous phase and an oil component is contained in the oil phase. The method is not particularly limited as long as it is a method capable of producing the cosmetic material W).

  For example, water, a silicon oxide-coated zinc oxide-containing aqueous composition of this 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 silicon oxide-coated zinc oxide-containing aqueous composition, the alkyl portion serves as an emulsifier. 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.

  Since the viscosity of the oil-in-water cosmetic of the present embodiment can be adjusted by the content of the water-soluble vinyl polymer contained in the silicon oxide-coated zinc oxide-containing aqueous composition, it is appropriately adjusted so that a desired viscosity is obtained. And mix.

  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.

  As described above, according to the silicon oxide-coated zinc oxide-containing aqueous composition of the present embodiment, since the zinc ion concentration is 30 ppm or less, the silicon oxide-coated zinc oxide is stably dispersed in water, and the ultraviolet ray shielding effect and use An oil-in-water cosmetic with excellent feeling can be obtained.

As the silicon oxide-coated zinc oxide, when the existence ratio in ^Q 3, ^{Q 4} environment of the presence ratio in ^{Q 3} environments of silicon oxide, silicon in the coating film was ^{Q 4, Q 3 + Q 4} ≧ 0.6 and ^Q 4 / ( When using silicon oxide-coated zinc oxide in which Q ³ + Q ⁴ ) ≧ 0.5 or silicon oxide-coated zinc oxide containing at least one selected from the group consisting of Mg, Ca and Ba, In the meantime, fluctuations in the viscosity and pH of the cosmetic are suppressed.

Furthermore, when the silicon oxide-coated zinc oxide-containing aqueous composition of the present embodiment contains a chelating agent, fluctuations in the viscosity and pH of the cosmetic are further suppressed.
Further, when the silicon oxide-coated zinc oxide-containing aqueous composition of the present embodiment contains an organic ultraviolet shielding agent, an excellent ultraviolet shielding effect can be obtained for cosmetics due to a synergistic effect with zinc oxide.

According to the oil-in-water cosmetic of the present embodiment, since it contains the silicon oxide-coated zinc oxide-containing aqueous composition of the present embodiment, it is possible to obtain a cosmetic excellent in ultraviolet shielding properties and feeling of use.
Further, as the silicon oxide-coated zinc oxide, when the existence ratio of the presence ratio in ^{Q 3} environments of silicon oxide, silicon in the coating in ^Q 3, ^{Q 4} environment was ^{Q 4, Q 3 + Q 4} ≧ 0.6 and ^{Q 4} When using silicon oxide-coated zinc oxide satisfying / (Q ³ + Q ⁴ ) ≧ 0.5 or silicon oxide-coated zinc oxide containing at least one selected from the group consisting of Mg, Ca and Ba, It is possible to suppress deterioration in performance as a cosmetic material, discoloration, and the like due to changes in viscosity and pH, and maintain the stability of the quality of the cosmetic material.

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

[Production example]
Zinc oxide particles (average particle diameter 250 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 particle content of 50% by mass.
Next, this zinc oxide aqueous suspension was 17.7% by mass in terms of silicon oxide with respect to the mass of zinc oxide particles in the zinc oxide aqueous suspension (15 mass of silicon oxide in silicon oxide-coated zinc oxide). %) Sodium silicate aqueous solution containing sodium silicate and stirred to obtain a suspension.

The suspension was then warmed to 60 ° C. and dilute hydrochloric acid was gradually added while stirring the suspension to adjust the pH to 6. Then, after leaving still for 2 hours, the calcium chloride aqueous solution (calcium chloride dihydrate 50 mass%) of the mass same as the mass of the zinc oxide particle in this suspension was further added and stirred, and also for 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 (firing) at 500 ° C. for 1 hour to produce silicon oxide-coated zinc oxide of Production Example.

  As a result of measuring the contents of Na and Ca in the silicon oxide-coated zinc oxide of Production Example by atomic absorption spectrometry, Na was 0.12% by mass and Ca was 0.10% by mass.

[Example 1]
98.5 parts by mass of pure water and 0.4 parts by mass of an alkyl-modified carboxyvinyl polymer (trade name: PEMULEN TR-1, manufactured by Lubrizol Advanced Materials) were mixed with a homodisper.
Next, an aqueous sodium hydroxide solution was added to this mixed solution to adjust the hydrogen ion index (pH) to 6.0, and pure water was added to adjust to 100 parts by mass to obtain carbomer gel A.
60 parts by mass of the obtained carbomer gel A, 10 parts by mass of glycerin, and 30 parts by mass of silicon oxide-coated zinc oxide were homodispers (trade name: Lab Solution (A TYPE) homodisper 2.5 type, Primix And an aqueous composition containing silicon oxide-coated zinc oxide containing 30% by mass of silicon oxide-coated zinc oxide was obtained.

[Evaluation]
The silicon oxide-coated zinc oxide-containing aqueous composition obtained in Example 1 was centrifuged.
After the supernatant obtained by centrifugation was solid-liquid separated with a 0.05 μm filter, the zinc ion concentration was measured by high frequency inductively coupled plasma emission spectroscopy (ICP-AES).
The results are shown in Table 1.

[Example 2]
98.5 parts by mass of pure water and 0.2 part by mass of carboxyvinyl polymer (trade name: Carbopol Ultraz 10 polymer, manufactured by Lubrizol Advanced Materials) were manually mixed.
Next, an aqueous sodium hydroxide solution was added to this mixed solution to adjust the hydrogen ion index (pH) to 7.5, and pure water was added to adjust to 100 parts by mass to obtain carbomer gel B.
83.3 parts by mass of the obtained carbomer gel B and 16.7 parts by mass of the silicon oxide-coated zinc oxide-containing aqueous composition obtained in Example 1 were mixed, and the content of silicon oxide-coated zinc oxide was 5 A water-based composition (gel form) containing silicon oxide-coated zinc oxide of mass% was obtained.
Moreover, 76.7 parts by mass of Carbomer Gel B and 23.3 parts by mass of the silicon oxide-coated zinc oxide-containing aqueous composition obtained in Example 1 were mixed, and the content of silicon oxide-coated zinc oxide was 7 parts by mass. % Silicon oxide-coated zinc oxide-containing aqueous composition (gel).
Further, 66.7 parts by mass of carbomer gel B and 33.3 parts by mass of the silicon oxide-coated zinc oxide-containing aqueous composition obtained in Example 1 were mixed, and the content of silicon oxide-coated zinc oxide was 10 masses. % Silicon oxide-coated zinc oxide-containing aqueous composition (gel).

[Evaluation of transmittance and SPF value]
The transmittance and SPF value of the gel-like silicon oxide-coated zinc oxide-containing aqueous composition were measured.
The transmittance (%) and SPF value of the silicon oxide-coated zinc oxide-containing aqueous composition were measured using an SPF analyzer UV-1000S (manufactured by Labsphere). The transmittance measurement results are shown in FIG. 1, and the SPF value measurement results are shown in FIG.

[Example 3]
[Evaluation of viscosity]
The silicon oxide-coated zinc oxide-containing aqueous composition (gel form) having a silicon oxide-coated zinc oxide content of Example 2 of 5% by mass is stored at 40 ° C. as the silicon oxide-coated zinc oxide-containing aqueous composition of Example 3. The viscosity was measured every predetermined time. The viscosity was measured using a BII rotational viscometer (manufactured by Toki Sangyo Co., Ltd.) at 20 ° C. and 30 rpm.
The measurement results of the viscosity are shown in FIG.

[Example 4]
71.4 parts by mass of the silicon oxide-coated zinc oxide-containing aqueous composition obtained in Example 1 and 28.6 parts by mass of the silicon oxide-coated zinc oxide used in Example 1 were dispersed with a homodisper to obtain silicon oxide. A silicon oxide-coated zinc oxide-containing aqueous composition containing 50% by mass of the coated zinc oxide was obtained.

[Evaluation]
The silicon oxide-coated zinc oxide-containing aqueous composition obtained in Example 4 was centrifuged.
After the supernatant obtained by centrifugation was solid-liquid separated with a 0.05 μm filter, the zinc ion concentration was measured in the same manner as in Example 1.
The results are shown in Table 1.

[Example 5]
90 parts by mass of the carbomer gel B obtained in Example 2 and 10 parts by mass of the silicon oxide-coated zinc oxide-containing aqueous composition obtained in Example 4 were mixed, and the content of silicon oxide-coated zinc oxide was 5 A water-based composition (gel form) containing silicon oxide-coated zinc oxide of mass% was obtained.
Further, 86 parts by mass of carbomer gel B and 14 parts by mass of the silicon oxide-coated zinc oxide-containing aqueous composition obtained in Example 1 were mixed, and the silicon oxide-coated zinc oxide content was 7% by mass. A coated zinc oxide-containing aqueous composition (gel) was obtained.
Further, 80 parts by mass of carbomer gel B and 20 parts by mass of the silicon oxide-coated zinc oxide-containing aqueous composition obtained in Example 1 were mixed, and the silicon oxide-coated zinc oxide content was 10% by mass. A coated zinc oxide-containing aqueous composition (gel) was obtained.

[Evaluation]
The transmittance and SPF value of the above-described silicon oxide-coated zinc oxide-containing aqueous composition were measured.
The transmittance of the silicon oxide-coated zinc oxide-containing aqueous composition was measured in the same manner as in Example 2. The results are shown in FIG.
The SPF value of the silicon oxide-coated zinc oxide-containing aqueous composition was measured in the same manner as in Example 2. The results are shown in FIG.

[Example 6]
[Evaluation of viscosity]
The silicon oxide-coated zinc oxide-containing aqueous composition (gel form) having a silicon oxide-coated zinc oxide content of Example 5 of 5% by mass is stored at 40 ° C. as the silicon oxide-coated zinc oxide-containing aqueous composition of Example 6. The viscosity was measured every predetermined time. The viscosity was measured using a BII rotational viscometer (manufactured by Toki Sangyo Co., Ltd.) at 20 ° C. and 30 rpm.
The measurement results of the viscosity are shown in FIG.

[Comparative Example 1]
60 parts by mass of carbomer gel A obtained in Example 1, 10 parts by mass of glycerin, and 30 parts by mass of silicon oxide-coated zinc oxide were dispersed in a bead mill using zirconia beads having a particle size of 0.03 mm. A silicon oxide-coated zinc oxide-containing aqueous composition containing 30% by mass of silicon oxide-coated zinc oxide was obtained.

[Evaluation]
The silicon oxide-coated zinc oxide-containing aqueous composition obtained in Comparative Example 1 was centrifuged.
After the supernatant obtained by centrifugation was solid-liquid separated with a 0.05 μm filter, the zinc ion concentration was measured in the same manner as in Example 1.
The results are shown in Table 1.

[Comparative Example 2]
83.3 parts by mass of carbomer gel B obtained in Example 2 and 16.7 parts by mass of the silicon oxide-coated zinc oxide-containing aqueous composition obtained in Comparative Example 1 were mixed to contain silicon oxide-coated zinc oxide. A silicon oxide-coated zinc oxide-containing aqueous composition (gel form) containing 5% by mass of the aqueous composition was obtained.

[Evaluation]
This silicon oxide-coated zinc oxide-containing aqueous composition was stored at 40 ° C., and the viscosity was measured every predetermined time. The viscosity was measured using a BII rotational viscometer (manufactured by Toki Sangyo Co., Ltd.) at 20 ° C. and 30 rpm.
The measurement results of the viscosity are shown in FIG.

From the results in Table 1, it was found that the zinc ion concentration in the silicon oxide-coated zinc oxide-containing aqueous composition can be reduced to 30 ppm or less by using a homodisper as in Example 1 and Example 4.
On the other hand, when a bead mill using zirconia beads is used as in Comparative Example 1, the zinc ion concentration in the silicon oxide-coated zinc oxide-containing aqueous composition is 230 ppm, and the zinc ion concentration cannot be reduced to 30 ppm or less. It was.

From the results of FIG. 1, it was found that the transmittance of the silicon oxide-coated zinc oxide-containing aqueous composition increases as the content of silicon oxide-coated zinc oxide decreases.
From the results of FIG. 2, it was found that the SPF value of the silicon oxide-coated zinc oxide-containing aqueous composition increases as the content of silicon oxide-coated zinc oxide increases.

From the results of FIG. 3, the silicon oxide-coated zinc oxide-containing aqueous compositions of Example 3 and Example 6 have a viscosity of 8 Pa · s or more after storage at 40 ° C. for 2 months, and are oil-in-water cosmetics. It has been found that it has sufficient characteristics required for.
On the other hand, the silicon oxide-coated zinc oxide-containing aqueous composition of Comparative Example 2 was found to have a viscosity of about 2 Pa · s immediately after preparation and does not have the characteristics required for oil-in-water cosmetics. .
That is, it was confirmed that an aqueous composition having excellent dispersion stability can be obtained by reducing the amount of zinc ions in the silicon oxide-coated zinc oxide-containing aqueous composition.

[Experimental example]
Zinc oxide was dissolved with hydrochloric acid to obtain an aqueous solution containing zinc ions.
The viscosity and pH of carbomer gel B were measured in the same manner as described above when an aqueous solution containing zinc ions was added to carbomer gel B of Example 2 so that the zinc ions were 0 ppm, 1 ppm, 10 ppm, 20 ppm, and 100 ppm. did. The results are shown in Table 2 and FIG.

  This experiment confirmed that as the zinc ion concentration increased, the viscosity of the carbomer gel decreased and the stability of the zinc oxide-containing aqueous composition decreased.

  The silicon oxide-coated zinc oxide-containing aqueous composition of the present invention comprises a zinc oxide-coated zinc oxide obtained by coating the surface of zinc oxide particles with a dense silicon oxide coating, a water-soluble vinyl polymer, and a zinc ion concentration of 30 ppm. By making it below, an aqueous dispersion excellent in dispersion stability can be obtained. For this reason, UV-shielding ability is required, and it is not only applicable to oil-in-water cosmetics with excellent usability, but when used in fields other than cosmetics, the choice of dispersants and resins is widened, and paints, etc. The degree of freedom in designing and blending can be increased, and its industrial value is great.

Claims (5)

Containing water, a water-soluble vinyl polymer, and silicon oxide-coated zinc oxide;
Zinc ion concentration is Ri der less than 30ppm,
The mass percentage of the alkali metal contained in the silicon oxide film in the silicon oxide-coated zinc oxide is 0.0001 mass% or more and 0.8 mass% or less,
The Mg contained in the silicon oxide in the film in the silicon oxide-coated zinc oxide, at least one of the sum of the percentages by weight are Rukoto der 0.01 mass% or more and 1 wt% selected from the group consisting of Ca and Ba A silicon oxide-coated zinc oxide-containing aqueous composition. The water-soluble vinyl polymer contains an alkyl-modified carboxyvinyl polymer, and the content of the alkyl-modified carboxyvinyl polymer with respect to 100 parts by mass of the silicon oxide-coated zinc oxide is 0.02 parts by mass or more and 1.5 parts by mass or less. The silicon oxide-coated zinc oxide-containing aqueous composition according to claim 1, wherein The water-soluble vinyl polymer includes an alkyl-modified carboxyvinyl polymer and a carboxyvinyl polymer,
3. The silicon oxide-coated zinc oxide-containing aqueous composition according to claim 1, wherein the content of the water-soluble vinyl polymer is 0.1 parts by mass or more and 5.0 parts by mass or less. Contains alcohols,
The alcohols Ri Oh monohydric or polyhydric alcohols having 1 to 6 carbon atoms,
Silicon oxide-coated oxide according to claim 1, the content of the alcohol with respect to the silicon oxide-coated zinc oxide 100 parts by weight, characterized in der Rukoto 100 parts by mass or less than 10 parts by weight A zinc-containing aqueous composition.   An oil-in-water cosmetic comprising the aqueous phase containing the silicon oxide-coated zinc oxide-containing aqueous composition according to any one of claims 1 to 4.

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