JP6349875B2 - Silicon oxide-coated zinc oxide, production method thereof, silicon oxide-coated zinc oxide-containing composition, and cosmetics - Google Patents

Description

  The present invention relates to a silicon oxide-coated zinc oxide, a method for producing the same, a silicon oxide-coated zinc oxide-containing composition, and a cosmetic, and more particularly, a lotion, a sunscreen gel, an emulsion, a cream, The present invention relates to a silicon oxide-coated zinc oxide suitable for use in foundations, lipsticks, blushers, eye shadows, and the like, a production method thereof, a silicon oxide-coated zinc oxide-containing composition, and a cosmetic.

Ultraviolet rays cause deterioration of many substances such as resin and rubber, and it is said that it can cause not only suntan and sunburn but also aging and skin cancer. Therefore, ultraviolet shielding agents are widely used in the fields of films, paints, cosmetics and the like.
As the ultraviolet shielding agent, an organic ultraviolet shielding agent such as benzophenone, methoxycinnamic acid or dibenzoylmethane, or an inorganic ultraviolet shielding agent such as zinc oxide or titanium oxide is generally used.

Organic UV screening agents may be deteriorated by heat or long-term UV irradiation, and a single organic UV screening agent alone cannot absorb a wide range of UV rays. There are problems such as the need to use a combination of various organic ultraviolet screening agents.
On the other hand, the inorganic ultraviolet shielding agent shields ultraviolet rays due to the effect of absorbing ultraviolet rays having a wavelength corresponding to the band gap of the inorganic particles contained therein and the scattering caused by the refractive index of the inorganic particles. There is no deterioration due to ultraviolet irradiation for a long time, excellent weather resistance, heat resistance, etc., and there is an advantage that ultraviolet rays in a wide wavelength region can be shielded.
By the way, even in the inorganic ultraviolet shielding agent having such advantages, it scatters not only ultraviolet rays but also visible light. Therefore, when a large amount of such inorganic ultraviolet shielding agents are blended into cosmetics, it becomes white. Therefore, in order to cope with such a problem, an inorganic ultraviolet shielding agent is appropriately used in combination with an organic ultraviolet shielding agent.

In general, titanium oxide, zinc oxide or the like is used as the inorganic ultraviolet shielding agent. In particular, zinc oxide can shield ultraviolet rays in a wide wavelength range from the UV-A region (320 nm to 400 nm) to the UV-B region (280 nm to 320 nm).
For example, when the photocatalytic activity for oxidizing a substance in contact with the particle surface is compared between zinc oxide and titanium oxide, zinc oxide is much lower. Moreover, since the refractive index of zinc oxide is 2.0 and lower than the refractive index of titanium oxide 2.7, when it is made into nanoparticles, it has excellent transparency. Therefore, zinc oxide has attracted attention as an ultraviolet shielding agent.

On the other hand, since zinc is an amphoteric element, its oxide zinc oxide is easily dissolved in acids and alkalis, and is also soluble in water and releases zinc ions, which is stable. It makes the sex insufficient.
Further, with respect to the photocatalytic activity, zinc oxide is very low as compared with titanium oxide, but it is desirable to suppress it. For example, when zinc oxide is nanoparticulated so that the average particle diameter is 50 nm or less, the photocatalytic activity is increased because the specific surface area is increased.
Thus, in zinc oxide particles, the release of zinc ions and high photocatalytic activity are particularly significant problems.

In addition, water-based cosmetics are not particularly sticky as compared with oil-based cosmetics and provide a smooth feeling of use, so that they are particularly used in recent years as various cosmetics such as sunscreens, emulsions and creams. When zinc oxide is used in these water-based cosmetics, the eluted zinc ions react with water-soluble polymers such as organic UV-screening agents and thickeners, resulting in reduced performance, discoloration, and viscosity as cosmetics. There is a possibility that problems such as increase / decrease will occur, and thus there is a problem that the degree of freedom of prescription is limited.
For example, when carbomer (carboxyvinyl polymer), which is widely used as a thickener, is used in combination with zinc oxide, the gel structure of the carbomer is destroyed by the reaction between the eluted zinc ions and the carboxylate group (COO ⁻ ) of the carbomer. There is a problem that the viscosity is lowered.

Thus, in order to solve the problems of zinc oxide, various types of zinc oxide coated with an inorganic oxide have been proposed.
For example, a method of obtaining silica-coated zinc oxide by adding zinc oxide in a sodium silicate aqueous solution to make it in a suspended state and maintaining the hydrogen ion index (pH) at about 7 has been proposed (Patent Document). 1).
In addition, by contacting zinc oxide as a raw material with a silica coating-forming composition containing silicic acid containing no organic group and halogen or a precursor capable of producing silicic acid, water, an alkali, and an organic solvent, a photocatalyst is obtained. There has been proposed a method for obtaining silica-coated zinc oxide free from weathering deterioration due to action (Patent Document 2).

Japanese Patent No. 2851885 Japanese Patent No. 4582439

However, in the methods described in Patent Documents 1 and 2, since no elution of zinc ions has been studied, release of zinc ions from zinc oxide even when zinc oxide is coated with silica. There is a problem that it is difficult to sufficiently suppress the above.
In order to obtain a highly transparent cosmetic, zinc oxide having an average particle size of 50 nm or less is preferably used. When the average particle size of zinc oxide is reduced to 50 nm or less, the average particle size exceeds 50 nm. Compared with zinc oxide particles, there is a problem that the ultraviolet light scattering effect is reduced and the shielding ability of long-wavelength side, particularly long-wavelength ultraviolet light (UV-A) is inferior.

  The present invention has been made in view of the above circumstances, and is capable of suppressing elution of zinc ions from zinc oxide particles, a method for producing the same, and a silicon oxide-coated zinc oxide-containing composition. The object is to provide goods and cosmetics.

As a result of intensive studies to solve the above-mentioned problems, the present inventors have made a silicon oxide-coated zinc oxide obtained by coating the surface of zinc oxide particles having an average particle diameter of more than 50 nm and 500 nm or less with a silicon oxide film. for, 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 / (Q 3 + Q} 4) If ≧ 0.5, it was found that this silicon oxide film can prevent the elution of zinc ions from the zinc oxide particles. If this silicon oxide-coated zinc oxide is applied to cosmetics, the elution of zinc ions Therefore, the problem caused by elution of zinc ions was solved, and the ultraviolet ray shielding function was improved and the transparency was excellent, and the present invention was completed.

That is, the silicon oxide-coated zinc oxide of the present invention is a silicon oxide-coated zinc oxide formed by coating the surface of zinc oxide particles with a silicon oxide film, and the average particle diameter of the zinc oxide particles is more than 50 nm and 500 nm or less. , and the when the existence ratio in ^{Q 3} environment of silicon of the silicon oxide in the film were the presence ratio in ^Q 3, ^{Q 4} environment ^{Q 4, Q 3 + Q 4} ≧ 0.6 and ^Q 4 / ^(Q 3 + ^{Q 4} ) It is characterized by being ≧ 0.5.

It is preferable that the content rate of the said zinc oxide particle is 50 to 99 mass%.
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, the elution rate of zinc eluted in the aqueous solution is preferably 60% by mass or less.

  In the method for producing a silicon oxide-coated zinc oxide according to the present invention, zinc oxide particles are suspended in a solvent to form a zinc oxide suspension, and then the alkoxysilane and an alkoxy of 10-mer or less are added to the zinc oxide suspension. Any one or more of silane oligomers, a catalyst, and water are added and reacted, and then the obtained reaction product is heat-treated at a temperature of 150 ° C. or higher and lower than 600 ° C. Features.

  The silicon oxide-coated zinc oxide-containing composition of the present invention comprises the silicon oxide-coated zinc oxide of the present invention and a solvent.

  The cosmetic of the present invention is characterized by containing either or both of the silicon oxide-coated zinc oxide of the present invention and the silicon oxide-coated zinc oxide-containing composition of the present invention in a base.

According to the silicon oxide-coated zinc oxide of the present invention, the silicon oxide-coated zinc oxide obtained by coating the surface of the zinc oxide particles with a silicon oxide film has an average particle diameter of more than 50 nm and not more than 500 nm. when the existence ratio in ^{Q 3} environments of silicon in the film was the presence ratio in ^Q 3, ^{Q 4} environment ^{Q 4, Q 3 + Q 4} ≧ 0.6 and ^{Q 4 / (Q 3 + Q} 4) ≧ 0.5 As a result, the silicon oxide coating covers the surface of the zinc oxide particles, so that zinc ions can be prevented from eluting outward from the zinc oxide particles. Therefore, it is possible to prevent zinc ions from eluting outward from the silicon oxide-coated zinc oxide. Accordingly, it is possible to suppress a decrease in performance as a silicon oxide-coated zinc oxide due to elution of zinc ions, discoloration, increase / decrease in viscosity, and the like.

  According to the method for producing silicon oxide-coated zinc oxide of the present invention, zinc oxide particles are suspended in a solvent to form a zinc oxide suspension, and then the alkoxysilane and the 10-mer or less are added to the zinc oxide suspension. Any one or more of the alkoxysilane oligomers, a catalyst, and water are added and reacted, and then the resulting reaction product is heat-treated at a temperature of 150 ° C. or higher and lower than 600 ° C. Therefore, silicon oxide-coated zinc oxide that can prevent zinc ions from eluting outward from the zinc oxide particles can be easily and inexpensively produced.

  According to the silicon oxide-coated zinc oxide-containing composition of the present invention, since the silicon oxide-coated zinc oxide of the present invention and a solvent were contained, zinc ions were dissolved from the zinc oxide particles contained in the silicon oxide-coated zinc oxide. Elution into the inside can be suppressed. Therefore, performance degradation, discoloration, increase / decrease in viscosity, etc. as a silicon oxide-coated zinc oxide-containing composition due to elution of zinc ions can be suppressed.

  According to the cosmetic of the present invention, either or both of the silicon oxide-coated zinc oxide of the present invention and the silicon oxide-coated zinc oxide-containing composition of the present invention are contained in the base. It can suppress that the zinc element contained in any one or both among zinc and a silicon oxide covering zinc oxide containing composition elutes in a base as zinc ion. Accordingly, it is possible to suppress deterioration in performance as a cosmetic due to elution of zinc ions, discoloration, increase / decrease in viscosity, and the like.

It is a figure which shows the time-dependent change of the viscosity in 40 degreeC of each silicon oxide covering zinc oxide containing composition of Example 2 of this invention, and the carbomer aqueous solution of the comparative example 5. FIG.

The form for implementing the silicon oxide coating zinc oxide of this invention, its manufacturing method, a silicon oxide coating zinc oxide containing composition, and cosmetics is demonstrated.
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]
The silicon oxide-coated zinc oxide of one embodiment of the present invention is a silicon oxide-coated zinc oxide obtained by coating the surface of zinc oxide particles with a silicon oxide film, and the average particle diameter of the zinc oxide particles exceeds 50 nm and and at 500nm or less, when the abundance ratio of the presence ratio in ^{Q 3} environments of silicon of the silicon oxide in the coating film in ^Q 3, ^{Q 4} environment was ^{Q 4, Q 3 + Q 4} ≧ 0.6 and ^Q 4 / (Q ³ + Q ⁴ ) ≧ 0.5.

  The content of zinc oxide particles in the silicon oxide-coated zinc oxide is preferably 50% by mass or more and 99% by mass or less. Here, if the content of zinc oxide particles is less than 50% by mass, a desired ultraviolet shielding effect cannot be obtained. Therefore, when a desired ultraviolet shielding effect is to be obtained, a large amount of silicon oxide-coated zinc oxide is used. On the other hand, if the content of the zinc oxide particles exceeds 99% by mass, the ratio of the zinc oxide particles in the silicon oxide-coated zinc oxide becomes too high. As a result, the surface of the zinc oxide particles Is not preferable because it cannot be sufficiently covered with a silicon oxide film.

The average particle diameter of the silicon oxide-coated zinc oxide is preferably more than 50 nm and not more than 2000 nm, more preferably not less than 100 nm and not more than 500 nm, still more preferably not less than 200 nm and not more than 300 nm.
Here, the reason why the average particle size of the silicon oxide-coated zinc oxide is limited to the above range is that when the average particle size is 50 nm or less, the particle size of the zinc oxide to be contained also becomes small, and the scattering in the ultraviolet region on the long wavelength side On the other hand, if it exceeds 2000 nm, when this silicon oxide-coated zinc oxide is used for cosmetics or the like, there is a possibility that squeaks or the like may occur and the usability may deteriorate. It is.

The “average particle size” as used herein refers to the silicon oxide-coated zinc oxide when the silicon oxide-coated zinc oxide is observed using a transmission electron microscope (TEM) or a scanning electron microscope (SEM). It is a numerical value obtained by selecting a predetermined number, for example, 200 or 100, measuring the longest straight line portion (maximum major axis) of each of these silicon oxide-coated zinc oxides, and weighted averaging these measured values.
Here, when the silicon oxide-coated zinc oxide is aggregated, the aggregated particle diameter of the aggregate is not measured, but the silicon oxide-coated zinc oxide particles constituting the aggregate (primary A predetermined number of particles are measured to obtain an average particle diameter.

When this silicon oxide-coated zinc oxide is immersed in an aqueous solution having a hydrogen ion index (pH) of 5 so as to be 0.05% by mass for 1 hour, the dissolution rate of zinc eluted in this aqueous solution is 60% by mass or less. More preferably, it is 50 mass% or less, More preferably, it is 30 mass% or less.
Here, the reason for setting the elution rate of zinc to 60% by mass or less is that when the elution rate of zinc exceeds 60% by mass, the stability of the silicon oxide-coated zinc oxide itself is lowered, and this silicon oxide-coated zinc oxide is applied as a makeup. When applied to cosmetics, the eluted zinc ions react with water-soluble polymers such as organic UV-screening agents and thickeners, causing deterioration in performance as cosmetics, discoloration, increase / decrease in viscosity, etc. This is because it is not preferable.

This zinc elution rate is determined by, for example, dispersing silicon oxide-coated zinc oxide in a buffer solution of pH = 5 so as to be 0.05% by mass, stirring for 1 hour, and performing solid-liquid separation, and adjusting the zinc concentration in the liquid phase. It can be measured by measuring with an ICP emission spectrometer.
The buffer solution having pH = 5 may be any buffer solution that can disperse silicon oxide-coated zinc oxide. For example, 500 ml of 0.1 molar potassium hydrogen phthalate aqueous solution and 0.1 molar water A buffer solution in which the total amount is 1000 ml by adding water after mixing 226 ml of an aqueous sodium oxide solution is suitably used.

The silicon oxide-coated zinc oxide may be obtained by surface-treating the surface with a silicone resin.
This silicon oxide-coated zinc oxide is surface-treated with a silicone resin, so that the affinity to an oil phase, particularly silicone oil, is increased. Therefore, a water-in-oil type (W / O type) or an oil-in-water type ( O / W) can be easily incorporated into cosmetics.
That is, water-in-oil type (W / O type) by blending silicon oxide-coated zinc oxide surface-treated with silicone resin into the oil phase to make a water-in-oil or oil-in-water cosmetic. And elution of zinc ions in oil-in-water (O / W) cosmetics.

  The type of silicone resin used for the surface treatment is not particularly limited as long as it can be used as a cosmetic. Examples of such silicone resins include methyl hydrogen polysiloxane, dimethyl polysiloxane, methicone, hydrogen dimethicone, triethoxysilylethyl polydimethylsiloxyethyl dimethicone, triethoxysilylethyl polydimethylsiloxyethylhexyl dimethicone, (acrylates / acrylic acid (Tridecyl / triethoxysilylpropyl methacrylate / dimethicone methacrylate) copolymer, triethoxycaprylylsilane and the like. These may be used singly, a mixture of two or more of these may be used, or a copolymer thereof may be used.

  When the surface of this silicon oxide-coated zinc oxide is further surface-treated with a silicone resin, the surface treatment amount of the silicone resin in this surface treatment is the oil phase used in water-in-oil or oil-in-water cosmetics. For example, it is preferably 1% by mass to 20% by mass, and more preferably 3% by mass to 10% by mass with respect to the total mass of the silicon oxide-coated zinc oxide.

Hereinafter, each component of the silicon oxide-coated zinc oxide of this embodiment will be described in detail.
"Zinc oxide particles"
The average particle diameter of the zinc oxide particles is more than 50 nm and 500 nm or less, preferably 100 nm or more and 400 nm or less, more preferably 200 nm or more and 300 nm or less.

Here, the reason why the average particle diameter of the zinc oxide particles is limited to the above range will be described below.
Scattering by zinc oxide becomes Rayleigh scattering when the particle diameter of zinc oxide is sufficiently smaller than the wavelength, that is, when α << 1 in the following formula (1), generally α <0.4. If the diameter is larger than that, Mie scattering occurs. Therefore, in order to obtain the effect of Rayleigh scattering in the ultraviolet region, particularly in the UV-A region (320 nm to 400 nm), which has a longer wavelength, a particle diameter exceeding 50 nm is preferable.
α = π · D / λ (1)
(Where α is the particle size parameter, D is the particle size, and λ is the wavelength)

Therefore, when the average particle diameter of zinc oxide is 50 nm or less, as described above, Rayleigh scattering is inferior in scattering efficiency to Mie scattering, and the scattering effect may not be sufficiently obtained.
On the other hand, if the average particle size of zinc oxide exceeds 500 nm, the average particle size of silicon oxide-coated zinc oxide also increases, and when silicon oxide-coated zinc oxide is used in cosmetics, the transparency and usability in the visible light region are increased. There is a risk of damage.
The average particle diameter of the zinc oxide particles is determined by the same method as that for the silicon oxide-coated zinc oxide described above, that is, when the zinc oxide particles are observed using a transmission electron microscope (TEM) or the like. A predetermined number, for example, 200 or 100 zinc particles can be selected, the longest straight portion (maximum major axis) of each of these zinc oxide particles can be measured, and the measured values can be obtained by weighted averaging.

  The method for synthesizing zinc oxide particles is not particularly limited as long as it is a method capable of synthesizing zinc oxide particles having an average particle diameter of more than 50 nm and 500 nm or less. For example, the French method (indirect method), the United States Examples include a dry method such as a method (direct method) or a wet method such as a German method.

"Silicon oxide coating"
The silicon oxide film is, when the existence ratio in ^Q 3, ^{Q 4} environment of the presence ratio in ^{Q 3} Environment "silicon will be described later was ^{Q 4, Q 3 + Q 4} ≧ 0.6 and ^{Q 4 / (Q 3 + Q} 4 As long as the degree of condensation is high enough to satisfy “) ≧ 0.5”, there is no particular limitation.
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 the number of oxygen atoms bonded to two Si atoms in the oxygen atoms of the SiO ₄ tetrahedron unit, which is a constituent unit of silicon oxide, that is, two Si atoms. It is a chemical structure that depends on
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.

When the existence ratio in ^{Q 3} environments of silicon of the silicon oxide in the coating film was abundance in ^Q 3, ^{Q 4} environment ^{Q 4, Q 3 + Q 4} ≧ 0.6 and ^{Q 4 / (Q 3 + Q} 4) ≧ 0.5.
Here, although Q ³ + Q ⁴ ≧ 0.6 is satisfied, Q ⁴ / (Q ³ + Q ⁴ ) is less than 0.5 (Q ⁴ / (Q ³ + Q ⁴ ) <0.5), or Although Q ⁴ / (Q ³ + Q ⁴ ) ≧ 0.5 is satisfied, when Q ³ + Q ⁴ is less than 0.6 (Q ³ + Q ⁴ <0.6), the silicon oxide in the silicon oxide film Condensation does not proceed sufficiently, and therefore a dense film cannot be obtained. As a result, there is a possibility that the effect of suppressing the elution of zinc ions of silicon oxide-coated zinc oxide may not be obtained, which is not preferable.

[Method for producing silicon oxide-coated zinc oxide]
The method for producing a silicon oxide-coated zinc oxide according to the present embodiment includes a zinc oxide suspension preparation step in which zinc oxide particles are suspended in a solvent to form a zinc oxide suspension, A reaction step of adding and reacting any one or two or more of silane and an oligomer of alkoxysilane of 10-mer or less, a catalyst, and water, and the obtained reaction product is 150 ° C. or more and 600 ° C. And a heat treatment step of heat-treating at a temperature below.

"Zinc oxide suspension preparation process"
This is a step of suspending zinc oxide particles in a solvent to form a zinc oxide suspension.
The average particle diameter of the zinc oxide particles used here is more than 50 nm and 500 nm or less, preferably 100 nm or more and 400 nm or less, more preferably 200 nm or more and 300 nm or less.

  Here, the solvent for suspending the zinc oxide particles is not particularly limited as long as the solvent can suspend the zinc oxide particles, but water, methanol, ethanol, 1-propanol, 2- Alcohols such as propanol, 1-butanol, 2-butanol and octanol, esters such as ethyl acetate, butyl acetate, ethyl lactate, propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate and γ-butyrolactone; diethyl ether, ethylene Glycol monomethyl ether (methyl cellosolve), ethylene glycol monoethyl ether (ethyl cellosolve), ethylene glycol monobutyl ether (butyl cellosolve), diethylene glycol monomethyl ether, diethylene glycol Ethers such as monoethyl ether are preferably used.

Also, ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, acetylacetone, cyclohexanone, aromatic hydrocarbons such as benzene, toluene, xylene, ethylbenzene, amides such as dimethylformamide, N, N-dimethylacetoacetamide, and N-methylpyrrolidone Are also preferably used.
These solvents may be used alone or in combination of two or more.

  The content of zinc oxide particles in the zinc oxide suspension is preferably 1% by mass to 80% by mass, more preferably 20% by mass to 70% by mass, and even more preferably 30% by mass to 60% by mass. % Or less.

  Here, the reason why the content of zinc oxide particles in the zinc oxide suspension is 1% by mass or more and 80% by mass or less is that if the content of zinc oxide particles is less than 1% by mass, oxidation in the suspension is performed. It is necessary to remove a large amount of solvent as compared with the content of zinc particles, which may increase the cost. On the other hand, if the content exceeds 80% by mass, the viscosity of the suspension increases (thickens), the dispersion stability of the zinc oxide particles decreases, and the zinc oxide particles may easily settle.

The method for suspending zinc oxide particles in a solvent is not particularly limited, and a known suspension method can be used. For example, a bead mill using a medium such as zirconia beads, a ball mill, a homogenizer, a disper, a stirrer, or the like is preferably used. The time required for the suspension treatment may be sufficient as long as the zinc oxide particles are uniformly suspended in the solvent.
In this case, you may add a dispersing agent as needed.

"Reaction process"
To the zinc oxide suspension, one or more of alkoxysilane and oligomers of 10-mer or less alkoxysilane, a catalyst, and water are added, and the mixture is stirred for about 30 minutes to 24 hours. It is the process made to react.

Here, the reason for limiting to alkoxysilane and oligomers of 10-mer or less alkoxysilane is to obtain a dense silicon oxide film having a high degree of condensation of silicon oxide.
Note that the use of an alkali metal silicate instead of alkoxysilane is not preferable because it is difficult to improve the degree of condensation of silicon oxide in the silicon oxide film and a dense silicon oxide film cannot be obtained.
Moreover, the reason for limiting the alkoxysilane oligomer to the oligomer of alkoxysilane of 10 mer or less is that the distance between the oligomers is easily opened when the chain length of the oligomer is long, and the zinc oxide particles are coated in the 11 mer or more. This is because even if heat treatment is performed later, the silicon oxide in the coating does not sufficiently condense, so that a dense silicon oxide coating cannot be obtained and the desired elution suppression effect may not be obtained.

As said alkoxysilane, tetraalkoxysilane is preferable, and as said oligomer of 10 mer or less alkoxysilane, oligomer of tetramer or less tetramer is preferable.
This tetraalkoxysilane has the following general formula (2)
Si (OR) ₄ ...... (2)
(However, R is an alkoxyl group (RO group), and all of these four alkoxyl groups (RO groups) may be the same or partially or completely different). Is done. These alkoxyl groups preferably have 1 to 8 carbon atoms.

Examples of such tetraalkoxysilane include tetramethoxysilane, tetraethoxysilane, tetra n-propoxysilane, tetraisopropoxysilane, tetra n-butoxysilane, tetraisobutoxysilane, tetrasec-butoxysilane, tetra-t-butoxysilane. , Tetraphenoxysilane, monoethoxytrimethoxysilane, monobutoxytrimethoxysilane, monopentoxytrimethoxysilane, monohexoxytrimethoxysilane, dimethoxydiethoxysilane, dimethoxydibutoxysilane and the like.
Among these, tetramethoxysilane and tetraethoxysilane can be suitably used because they contain a large amount of Si and are easy to control the concentration when dispersed in a solvent and have high hydrolysis / condensation reactivity. .
These tetraalkoxysilanes may be used alone or in combination of two or more.

Moreover, the oligomer of tetraalkoxysilane of the above-mentioned 10-mer or less can be obtained by adding water to one or more tetraalkoxysilane monomers and hydrolyzing and condensing to some extent.
Such tetraalkoxysilane oligomers are MKC silicate MS51 (manufactured by Mitsubishi Chemical Corporation), methyl silicate 51 (average tetramer), methyl silicate 53A (average heptamer), ethyl silicate 40 (average 5 quantities). ), Ethyl silicate 48 (average 10-mer) (above, manufactured by Colecoat Co., Ltd.) and the like.

  Any one or two or more of the above tetraalkoxysilanes and tetraalkoxysilane oligomers of 10-mer or less are 2 with respect to the zinc oxide particles in the zinc oxide suspension when converted to silicon oxide. It is preferable to add so that it may become mass% or more and 45 mass% or less.

The catalyst is added for the purpose of accelerating the hydrolysis or polycondensation reaction of tetraalkoxysilane and an oligomer of tetraalkoxysilane of 10 or less. As such a catalyst, a known acid catalyst or basic catalyst can be used (see Sakuo Sakuo, “Science of Sol-Gel Method”, Agne Jofusha, Chapter 9 (p154-p173)).
Examples of the acid catalyst include inorganic acids such as hydrochloric acid, sulfuric acid, nitric acid and phosphoric acid; organic acids such as formic acid, acetic acid, oxalic acid, lactic acid and tartaric acid. Among these, inorganic acids, particularly hydrochloric acid are preferred. Can be used. Moreover, said acid catalyst may be used individually by 1 type, and may be used in combination of 2 or more type.

Examples of this basic catalyst include sodium hydroxide, potassium hydroxide, lithium hydroxide, cerium hydroxide, barium hydroxide, calcium hydroxide, pyridine, pyrrole, piperazine, pyrrolidine, piperidine, picoline, ammonia, methylamine, Ethylamine, propylamine, butylamine, dimethylamine, diethylamine, dipropylamine, dibutylamine, trimethylamine, triethylamine, tripropylamine, tributylamine, monoethanolamine, diethanolamine, dimethylmonoethanolamine, monomethyldiethanolamine, triethanolamine, diaza Bicyclooctane, diazabicyclononane, diazabicycloundecene, urea, tetramethylammonium hydroxide, tetraethylan Pyridinium hydroxide, tetrapropylammonium hydroxide, tetrabutylammonium hydroxide, benzyltrimethylammonium hydroxide, choline, and the like.
Among these, ammonia, organic amines, and ammonium hydroxides can be preferably used. These basic catalysts may be used alone or in combination of two or more.
These catalysts may be either acid catalysts or basic catalysts, but acid catalysts that are electrophilic reactions can be suitably used.

The reaction temperature is not particularly limited as long as the hydrolysis or polycondensation reaction of the tetraalkoxysilane and the tetraalkoxysilane oligomer of 10-mer or less proceeds rapidly, but preferably 0 ° C or more and 100 ° C or less, More preferably, they are 20 degreeC or more and 80 degrees C or less, More preferably, they are 40 degreeC or more and 60 degrees C or less.
Water is added in an amount that is at least the amount necessary to hydrolyze any one or more of tetraalkoxysilane and tetraalkoxysilane oligomers of 10-mer or less, that is, an amount that provides a hydrolysis rate of 100% or more. do it.

As a result, a reaction liquid in which any one or two or more hydrolysis reactions proceed among the alkoxysilanes and oligomers of the alkoxysilanes in 10-mer or less and the condensation reaction also proceeds is obtained.
A solid reaction product is obtained by solid-liquid separation of the reaction solution by atmospheric pressure filtration, vacuum filtration, pressure filtration, centrifugation, or the like.

"Heat treatment process"
In this step, the reactant is heat-treated at a temperature of 150 ° C. or higher and lower than 600 ° C.
In order to promote densification of the silicon oxide film, the heat treatment of the reaction product is more preferably 250 ° C. or more and 550 ° C. or less, and further preferably 300 ° C. or more and 500 ° C. or less.
Here, the reason why the heat treatment temperature is limited to 150 ° C. or more and less than 600 ° C. is that if it is less than 150 ° C., a sufficiently condensed dense silicon oxide film cannot be obtained, and as a result, zinc ions are eluted from the zinc oxide particles. This is because the effect of suppressing this may not be sufficiently obtained. On the other hand, at 600 ° C. or higher, the silicon oxide-coated zinc oxide on which the silicon oxide film is formed binds to form coarse particles, or the zinc oxide grows. As a result, cosmetics containing the silicon oxide-coated zinc oxide are blended. This is because there is a possibility that sufficient transparency cannot be obtained in the visible light region.

  This heat treatment step may be repeated a plurality of times at a predetermined temperature within this temperature range as long as the heat treatment temperature is in a temperature range of 150 ° C. or more and less than 600 ° C., or a plurality of times at different temperatures within this temperature range. You may go.

When the surface of the silicon oxide-coated zinc oxide thus obtained is further surface-treated with a silicone resin, a method of directly mixing the silicon oxide-coated zinc oxide after the heat treatment step and the silicone resin (dry method) Treatment method) or a method in which the silicon oxide-coated zinc oxide after the heat treatment step is dispersed in a solution containing a silicone resin, and then the solvent in the solution is removed, followed by heat treatment (wet process). A known method such as a treatment method can be used.
When the silicon oxide-coated zinc oxide after the heat treatment step is dispersed in a solution containing a silicone resin, the content of the silicon oxide-coated zinc oxide is 10% by mass or more and 40% by mass in the solution containing the silicone resin. % Or less, preferably 25% by mass or more and 35% by mass or less. By mixing in this range, production efficiency can be improved.

The heat treatment when the surface treatment is performed with the silicone resin is preferably performed in a temperature range of 100 ° C. or more and 300 ° C. or less. By performing the heat treatment in this temperature range, the surface of the silicon oxide-coated zinc oxide can be surface-treated with a silicone resin, and thermal decomposition of the silicone resin and crystal growth of zinc oxide can be suppressed.
As described above, the silicon oxide-coated zinc oxide of this embodiment can be produced.

[Silicon oxide-coated zinc oxide-containing composition]
The silicon oxide-coated zinc oxide-containing composition of the present embodiment contains the above silicon oxide-coated zinc oxide and a solvent.

The average particle diameter of the silicon oxide-coated zinc oxide is preferably more than 50 nm and not more than 2000 nm, more preferably not less than 100 nm and not more than 500 nm, still more preferably not less than 200 nm and not more than 300 nm.
Here, the reason why the average particle size of the silicon oxide-coated zinc oxide is limited to the above range is that when the average particle size is 50 nm or less, the particle size of the zinc oxide to be contained also becomes small, and the scattering in the ultraviolet region on the long wavelength side This is because there is a concern that when the silicon oxide zinc oxide is used for cosmetics or the like, a squeak or the like may occur and the feeling of use may deteriorate.

The average dispersed particle diameter of the silicon oxide-coated zinc oxide in the silicon oxide-coated zinc oxide-containing composition is preferably 60 nm or more and 10 μm or less, more preferably 80 nm or more and 7 μm or less, more preferably 100 nm or more and 5 μm. It is as follows.
Here, the reason why the average dispersed particle size of the silicon oxide-coated zinc oxide is limited to the above range is that if the average dispersed particle size is less than 60 nm, the scattering in the ultraviolet region on the long wavelength side may be relatively small. On the other hand, if the average dispersed particle size exceeds 10 μm, the transparency may be lowered when this silicon oxide-coated zinc oxide-containing composition is blended in cosmetics, which is not preferable.

The silicon oxide-coated zinc oxide content in the silicon oxide-coated zinc oxide-containing composition may be appropriately adjusted in order to obtain the desired ultraviolet shielding performance, and is not particularly limited, but is preferably 1% by mass or more And it is 80 mass% or less, More preferably, it is 20 mass% or more and 70 mass% or less, More preferably, it is 30 mass% or more and 60 mass% or less.
Here, the reason why the content of the silicon oxide-coated zinc oxide is 1% by mass or more and 80% by mass or less is that when the content of the silicon oxide-coated zinc oxide is less than 1% by mass, the composition has a sufficient ultraviolet shielding function. Therefore, it is necessary to add a large amount of the composition in order to show a desired ultraviolet shielding function when this composition is blended with cosmetics, etc., and the production cost is high. This is not preferable. On the other hand, if the content exceeds 80% by mass, the viscosity of the composition is increased, the dispersion stability of the silicon oxide-coated zinc oxide is lowered, and the silicon oxide-coated zinc oxide is liable to settle, which is not preferable.

The solvent is not particularly limited as long as it can disperse the silicon oxide-coated zinc oxide, and examples thereof include water, methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, Alcohols such as 2-butanol, octanol, glycerin;
Esters such as ethyl acetate, butyl acetate, ethyl lactate, propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate, γ-butyrolactone;
Ethers such as diethyl ether, ethylene glycol monomethyl ether (methyl cellosolve), ethylene glycol monoethyl ether (ethyl cellosolve), ethylene glycol monobutyl ether (butyl cellosolve), diethylene glycol monomethyl ether, diethylene glycol monoethyl ether;
Are preferably used.

In addition, ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, acetyl acetone, cyclohexanone;
Aromatic hydrocarbons such as benzene, toluene, xylene, ethylbenzene;
Cyclic hydrocarbons such as cyclohexane;
Amides such as dimethylformamide, N, N-dimethylacetoacetamide, N-methylpyrrolidone;
Linear polysiloxanes such as dimethylpolysiloxane, methylphenylpolysiloxane, diphenylpolysiloxane;
Are also preferably used.

And cyclic polysiloxanes such as octamethylcyclotetrasiloxane, decamethylcyclopentasiloxane, dodecamethylcyclohexanesiloxane;
Modified polysiloxanes such as amino-modified polysiloxane, polyether-modified polysiloxane, alkyl-modified polysiloxane, and fluorine-modified polysiloxane;
Are also preferably used.
These solvents may be used alone or in combination of two or more.

  The silicon oxide-coated zinc oxide-containing composition of the present embodiment may contain commonly used additives such as a dispersant, a stabilizer, a water-soluble binder, and a thickener as long as the properties are not impaired.

  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 depending on the particle diameter of the silicon oxide-coated zinc oxide and the type of the desired dispersion medium, and only one type of the above dispersants may be used, or two or more types may be used. May be used in combination.

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

As the thickener, when this silicon oxide-coated zinc oxide-containing composition is applied to cosmetics, it is not particularly limited as long as it is a thickener usable for cosmetics. For example, natural water-soluble polymers such as gelatin, casein, collagen, hyaluronic acid, albumin, starch, methylcellulose, ethylcellulose, methylhydroxypropylcellulose, carboxymethylcellulose, hydroxymethylcellulose, hydroxypropylcellulose, sodium carboxymethylcellulose, propylene glycol alginate Semi-synthetic polymers such as polyvinyl alcohol, polyvinyl pyrrolidone, carbomer (carboxyvinyl polymer), synthetic polymers such as polyacrylate and polyethylene oxide, inorganic minerals such as bentonite, laponite and hectorite are preferably used. These thickeners may be used alone or in combination of two or more.
Among these thickeners, a synthetic polymer is preferable, and a carbomer is more preferable.

Here, when carbomer is used as the thickener, the content of carbomer in the silicon oxide-coated zinc oxide-containing composition is preferably 0.01% by mass or more and 10% by mass or less, and 0.01% by mass. More preferably, the content is 3% by mass or less.
If the carbomer content in the silicon oxide-coated zinc oxide-containing composition is less than 0.01% by mass, the thickening effect may not be obtained. On the other hand, the carbomer content is 10% by mass. If it exceeds, the viscosity will become too high, and when applied to cosmetics, the riding on the skin when spread and applied to the skin will worsen, causing problems such as reduced usability, It is not preferable from the viewpoint.

The hydrogen ion index (pH) in the silicon oxide-coated zinc oxide-containing composition when carbomer is used as the thickener is preferably 5 or more and 10 or less, more preferably 6 or more and 10 or less, and 7 or more and 9 or less. Is more preferable.
By setting the pH of the silicon oxide-coated zinc oxide-containing composition within the above range, changes with time such as viscosity can be suppressed.

The above carbomer (carboxyvinyl polymer) is widely used as a thickener for water-based cosmetics, but it thickens (gels) using the interaction between carboxyl groups or between carboxylate groups. In the presence of zinc ions, the network structure of the carbomer is destroyed and the viscosity cannot be kept constant. Therefore, when several mass% of zinc oxide is mixed with the carbomer aqueous solution whose viscosity has been adjusted, the viscosity reduction proceeds within a few hours.
Even in the case of using zinc oxide coated with an inorganic oxide or resin to suppress surface activity, in many cases, the viscosity reduction or phase separation proceeds within a few hours to a few days. Therefore, when carbomer and zinc oxide are used in combination, it becomes a problem to suppress or reduce a decrease in viscosity of a mixture containing them.

In addition, when zinc oxide, which is coated with a conventional inorganic oxide or resin and suppresses surface activity, is used to suppress the decrease in viscosity of the carbomer aqueous solution, the viscosity decrease after a certain period of time often occurs rather than the initial viscosity decrease. It becomes a big problem.
The initial decrease in viscosity can be dealt with by adjusting the viscosity of the carbomer aqueous solution to a high value in advance, but if the viscosity changes in the medium to long term after a certain period of time, the properties of the cosmetics change at the distribution stage. However, the stability over time is impaired. In particular, zinc oxide surface-treated with an inorganic oxide or a resin has a certain elution suppressing effect, and thus there is a possibility that zinc ions are gradually eluted over a medium to long term.
Conventionally, there are few reports on the viscosity change of a composition containing a carbomer, and even if there is a report example, suppression has been confirmed only up to a viscosity change over time of about 7 days at room temperature.

  The silicon oxide-coated zinc oxide-containing composition of the present embodiment uses silicon oxide-coated zinc oxide, which has a higher zinc elution suppression effect than zinc oxide coated with conventional inorganic oxides and resins. Even when a carbomer is used as a sticking agent, a decrease in viscosity with time is small, and therefore a composition having excellent quality stability over a long period of time can be obtained.

In the silicon oxide-coated zinc oxide-containing composition of the present embodiment, the viscosity after 300 hours when stored at 40 ° C., for example, under accelerated conditions that promote chemical reaction, is the viscosity after the initial viscosity reduction, for example, after 15 hours. The value divided by the viscosity is preferably 0.8 or more and 1.2 or less.
Thus, by setting the value obtained by dividing the viscosity after 300 hours under the accelerating condition by the viscosity after the decrease in the initial viscosity within the above range, the viscosity of the silicon oxide-coated zinc oxide-containing composition can be maintained over the medium to long term. It can be maintained and has excellent stability over time.

When the silicon oxide-coated zinc oxide-containing composition of the present embodiment has a silicon oxide-coated zinc oxide content of 15% by mass and this composition is a coating having a thickness of 32 μm, the transmittance for light having a wavelength of 450 nm is: 50% or more is preferable, 60% or more is more preferable, and 70% or more is more preferable.
This transmittance is obtained by coating a silicon oxide-coated zinc oxide-containing composition containing 15% by mass of silicon oxide-coated zinc oxide on a quartz substrate with a bar coater to form a coating film having a thickness of 32 μm. The spectral transmittance of the film can be determined by measuring with a SPF analyzer UV-1000S (manufactured by Labsphere).

The method for producing the silicon oxide-coated zinc oxide-containing composition of the present embodiment is not particularly limited as long as the silicon oxide-coated zinc oxide can be dispersed in the solvent.
As such a dispersion method, a known dispersion method can be used. For example, besides a stirrer, 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 are preferably used.
The time required for the dispersion treatment may be a time sufficient to uniformly disperse the silicon oxide-coated zinc oxide in the solvent.

  Next, as a specific example of the silicon oxide-coated zinc oxide-containing composition of the present embodiment, (1) a silicon oxide-coated zinc oxide-containing silicone in which silicon oxide-coated zinc oxide is dispersed in a silicone resin that is a water-insoluble dispersion medium The resin-based composition and (2) the silicon oxide-coated zinc oxide-containing aqueous composition in which silicon oxide-coated zinc oxide is dispersed in water will be described.

"Silicon resin-based zinc oxide-containing silicone resin composition"
This silicon oxide-coated zinc oxide-containing silicone resin-based composition is a silicone resin-based composition obtained by dispersing the above-described silicon oxide-coated zinc oxide in a silicone resin, and the content of this silicon oxide-coated zinc oxide is 1 mass. % Or more and 80% by mass or less, more preferably 20% by mass or more and 70% by mass or less, and further preferably 30% by mass or more and 60% by mass or less.

The average particle diameter of the silicon oxide-coated zinc oxide is preferably more than 50 nm and not more than 2000 nm, more preferably not less than 100 nm and not more than 500 nm, still more preferably not less than 200 nm and not more than 300 nm.
The average dispersed particle size of the silicon oxide-coated zinc oxide in the silicon oxide-coated zinc oxide-containing silicone resin composition is preferably 60 nm or more and 10 μm or less, more preferably 80 nm or more and 7 μm or less, and still more preferably 100 nm. Above and below 5 μm.

The silicone resin is not particularly limited as long as it is used in cosmetics. For example, a cyclic silicone resin or a linear silicone resin can be used.
Examples of such silicone resins include chain siloxanes such as dimethylpolysiloxane, methylphenylpolysiloxane, diphenylpolysiloxane, and methylhydrogenpolysiloxane, hexamethylcyclotrisiloxane, octamethylcyclotetrasiloxane, and decamethylpentasiloxane. And cyclic siloxanes such as decamethylcyclopentasiloxane, dodecamethylcyclohexanesiloxane, and tetramethyltetrahydrogenpolysiloxane, modified silicones such as amino-modified silicone, polyether-modified silicone, and alkyl-modified silicone, and methyltrimethicone.
These silicone resins may be used alone or in combination of two or more.

This silicon oxide-coated zinc oxide-containing silicone resin-based composition may contain a dispersant.
Examples of the dispersant include modified silicones such as polyether-modified silicone, polyglycerin-modified silicone, amino-modified silicone, phenyl-modified silicone, alkyl-modified silicone, carbinol-modified silicone, and dimethylsilicone;
Surfactants such as anionic surfactants, cationic surfactants, amphoteric surfactants, nonionic surfactants;
Silane coupling agents such as organoalkoxysilanes and organochlorosilanes;
Etc.
These dispersants may be used alone or in combination of two or more.

The amount of the dispersant added is preferably in the range of 1% by mass to 50% by mass with respect to the mass of the silicon oxide-coated zinc oxide in the silicon oxide-coated zinc oxide-containing silicone resin composition.
By adjusting the addition amount of the dispersant within the above range, even when this silicon oxide-coated zinc oxide-containing silicone resin composition is used alone or when directly mixed with cosmetics, Transparency can be sufficiently ensured when spread and coated on.
Further, natural oil, humectant, thickener, fragrance, preservative and the like may be further mixed with the silicon oxide-coated zinc oxide-containing silicone resin-based composition as long as the characteristics are not impaired.

This silicon oxide-coated zinc oxide-containing silicone resin composition may be emulsified with an aqueous component as an oil phase to form an emulsified composition.
The oil phase preferably contains at least one of a higher alcohol and a higher fatty acid, and more preferably contains both. By containing these components in the oil phase, the firmness and moisturizing feeling are improved, and the sustainability of these effects is improved.

  The higher alcohol is not particularly limited as long as it is used as a cosmetic, and for example, capryl alcohol, lauryl alcohol, stearyl alcohol, oleyl alcohol, myristyl alcohol, cetyl alcohol, cholesterol, phytosterol and the like are preferably used. These may be used alone or in combination of two or more.

As the higher fatty acid, 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 may be used alone or in combination of two or more.
In this oil phase, oil-soluble preservatives, ultraviolet absorbers, oil-soluble drugs, oil-soluble pigments, oil-soluble proteins, vegetable oils, animal oils and the like may be appropriately mixed as necessary.

The method for producing the silicon oxide-coated zinc oxide-containing silicone resin composition is not particularly limited as long as the silicon oxide-coated zinc oxide can be dispersed in the silicone resin.
As such a dispersion method, a known dispersion device can be used. As such a dispersing device, for example, a stirrer, a bead mill, a ball mill, a homogenizer, an ultrasonic disperser, a kneader, a three-roll mill, a rotation / revolution mixer, and the like are preferably used.
The time required for the dispersion treatment is not particularly limited as long as it is sufficient for the silicon oxide-coated zinc oxide to be uniformly dispersed in the silicone resin.

"Aqueous composition containing zinc oxide coated zinc oxide"
This silicon oxide-coated zinc oxide-containing aqueous composition is an aqueous composition obtained by dispersing the above-mentioned silicon oxide-coated zinc oxide in an aqueous dispersion medium containing alcohols, and the content ratio of this silicon oxide-coated zinc oxide is 1 It is contained in an amount of not less than 80% by mass and not more than 80% by mass, more preferably not less than 20% by mass and not more than 70% by mass, more preferably not less than 30% by mass and not more than 60% by mass. And it is an aqueous composition containing 20 mass% or less.

The average particle diameter of the silicon oxide-coated zinc oxide is preferably more than 50 nm and not more than 2000 nm, more preferably not less than 100 nm and not more than 500 nm, still more preferably not less than 200 nm and not more than 300 nm.
The average dispersed particle size of the silicon oxide-coated zinc oxide in the silicon oxide-coated zinc oxide-containing aqueous composition is preferably 60 nm or more and 10 μm or less, more preferably 80 nm or more and 7 μm or less, and still more preferably 100 nm or more and 5 μm or less.

  Here, the aqueous dispersion medium containing alcohols is a dispersion medium containing alcohols and water. Examples of alcohols include ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, octanol, Examples thereof include monohydric alcohols or polyhydric alcohols having 1 to 6 carbon atoms such as glycerin, 1,3-butylene glycol, propylene glycol, and sorbitol. Of these, monohydric alcohols, particularly ethanol, are preferred.

When this aqueous composition is composed of the above-described silicon oxide-coated zinc oxide and an aqueous dispersion medium containing alcohols, the alcohol content is preferably 5% by mass or more and 20% by mass or less, more preferably It is 10 mass% or more and 20 mass% or less.
In particular, when the alcohol content is 10% by mass or more and 20% by mass or less, the dispersibility and stability over time of the aqueous composition of the silicon oxide-coated zinc oxide can be improved.

  In this silicon oxide-coated zinc oxide-containing aqueous composition, the water-soluble polymer is further contained in an amount of 0.001% by mass to 10% by mass, more preferably 0.005% by mass and 5% by mass, and still more preferably 0%. It is good also as containing 0.01 mass% or more and 3 mass% or less. In this case, it is necessary to adjust the content of each component so that the total content of each of the silicon oxide-coated zinc oxide, the aqueous dispersion medium containing alcohols, and the water-soluble polymer does not exceed 100% by mass.

When applying this silicon oxide-coated zinc oxide-containing aqueous composition to cosmetics, the water-soluble polymer contained in this aqueous composition is not particularly limited as long as it can be used for cosmetics, Gum arabic, sodium alginate, casein, carrageenan, galactan, carboxyvinyl polymer, carboxymethylcellulose, sodium carboxymethylcellulose, carboxymethyl starch, agar, xanthan gum, quince seed, guar gum, collagen, gelatin, cellulose, dextran, dextrin, tragacanth gum, hydroxyethylcellulose , Hydroxypropylcellulose, sodium hyaluronate pectin, pullulan, methylcellulose, methylhydroxypropylcellulose and the like. These water-soluble polymers may be used alone or in combination of two or more.
This water-soluble polymer has a role as a dispersant and a viscosity modifier, and when added to the aqueous composition, the dispersibility and temporal stability of the silicon oxide-coated zinc oxide in the aqueous composition are also improved.

When the aqueous composition contains a water-soluble polymer, the content of the alcohol is preferably 5% by mass or more and 20% by mass or less, more preferably 15% by mass or more and 20% by mass or less.
Here, the reason why the content of the alcohol in the case where the water-based composition includes a water-soluble polymer is 5% by mass or more and 20% by mass or less is that the content of the alcohol is less than 5% by mass. Since the amount is too small, the water-soluble polymer cannot uniformly infiltrate into the alcohols and swells non-uniformly with moisture. As a result, the dispersibility of the silicon oxide-coated zinc oxide is reduced, making it difficult to handle. Furthermore, since the temporal stability of the aqueous composition is lowered, it is not preferable.
On the other hand, when the content exceeds 20% by mass, the viscosity of the entire aqueous composition is increased, the dispersion stability of the silicon oxide-coated zinc oxide is decreased, and the temporal stability of the aqueous composition is also decreased. .

In this silicon oxide-coated zinc oxide-containing aqueous composition, the above-mentioned silicon oxide-coated zinc oxide is mixed with an aqueous dispersion medium containing alcohols or an aqueous dispersion medium containing alcohols and a water-soluble polymer, and then water is added. It can be obtained by mixing and dispersing. The amount of water may be appropriately adjusted, but considering the dispersion stability and aging stability of the silicon oxide-coated zinc oxide, a range of 15% by mass to 94% by mass is preferable.
By adjusting the amount of water in the above range, it can be used alone or mixed with cosmetics, and it can be sufficiently coated with the silicon oxide coating to ensure sufficient transparency when applied to the skin. A zinc-containing aqueous composition is obtained.
This silicon oxide-coated zinc oxide-containing aqueous composition may be mixed as an aqueous phase with an oil phase and emulsified to form an emulsified composition.

[Cosmetics]
The cosmetic of this embodiment contains either or both of the silicon oxide-coated zinc oxide and the silicon oxide-coated zinc oxide-containing composition in the base.
When this silicon oxide-coated zinc oxide is used for ultraviolet shielding applications, the average particle diameter of the silicon oxide-coated zinc oxide is preferably more than 50 nm and not more than 2000 nm, more preferably not less than 100 nm and not more than 500 nm, More preferably, a material having a thickness of 200 nm or more and 300 nm or less is used.

Further, even when this silicon oxide-coated zinc oxide-containing composition is used for ultraviolet shielding applications, the average particle diameter of the silicon oxide-coated zinc oxide contained in the silicon oxide-coated zinc oxide-containing composition is more than 50 nm and not more than 2000 nm. It is preferable to use those having a thickness of 100 nm to 500 nm, more preferably 200 nm to 300 nm.
The average dispersed particle size of the cosmetic is preferably 60 nm or more and 10 μm or less, more preferably 80 nm or more and 7 μm or less, and further preferably 100 nm or more and 5 μm or less.

  The content of the silicon oxide-coated zinc oxide contained in the cosmetic using either one or both of the silicon oxide-coated zinc oxide and the silicon oxide-coated zinc oxide-containing composition may be appropriately adjusted. It is preferable to contain 1 mass% or more and 60 mass% or less with respect to the mass of the whole material. By containing the silicon oxide-coated zinc oxide within the above range, a sufficient transparency can be ensured, and there can be obtained a cosmetic having no rough feeling and having an excellent feeling of use.

The cosmetic of the present embodiment contains additives generally used in cosmetics, such as organic UV screening agents, inorganic UV screening agents, whitening agents, and the like within a range that does not impair the effects of the present invention. It may be.
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, Benzimidazole derivatives, imidazolines, bisbenzoazolyl derivatives, p-aminobenzoic acid (PABA) derivatives, methylenebis (hydroxyphenylbenzotriazole) derivatives, etc., and one or more selected from these groups It can be selected and used.

  In addition, examples of the inorganic ultraviolet shielding agent include oxides other than zinc oxide, such as titanium oxide and cerium oxide, and one or more of these groups can be appropriately selected and used.

This cosmetic comprises any one or both of the above-mentioned silicon oxide-coated zinc oxide and the above-mentioned silicon oxide-coated zinc oxide-containing composition in a base such as an emulsion, cream, foundation, lipstick, blusher, and eye shadow. It can be obtained by blending as usual.
Furthermore, one or both of the above-mentioned silicon oxide-coated zinc oxide and the above-mentioned silicon oxide-coated zinc oxide-containing composition are added to water-based cosmetics such as lotions and sunscreen gels, which have been difficult to formulate conventionally. By doing so, it is possible to obtain a water-based cosmetic excellent in ultraviolet shielding ability, transparency and feeling of use.

  Furthermore, by using this cosmetic as a cosmetic ingredient, it is possible to provide various cosmetics such as skin care cosmetics, makeup cosmetics, and body care cosmetics that are excellent in ultraviolet shielding ability, transparency, and feeling of use. In particular, it is suitable for sunscreens and the like of body care cosmetics that require ultraviolet shielding ability.

As described above, according to the silicon oxide-coated zinc oxide of the present embodiment, the surface of the zinc oxide particles is coated with the silicon oxide film, the average particle diameter of the zinc oxide particles is more than 50 nm and not more than 50 nm, 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 / (Q 3 + Q} 4) ≧ Since 0.5 is satisfied, the dense silicon oxide film covers the zinc oxide particles, so that zinc ions can be prevented from eluting outward from the zinc oxide particles. Therefore, when this silicon oxide-coated zinc oxide is applied to cosmetics, it is possible to suppress deterioration in performance as cosmetics due to elution of zinc ions, discoloration, increase / decrease in viscosity, and the like.

  According to the method for producing silicon oxide-coated zinc oxide of the present embodiment, a zinc oxide suspension preparation step in which zinc oxide particles are suspended in a solvent to form a zinc oxide suspension, and the zinc oxide suspension , A reaction step in which any one or two or more of alkoxysilane and an oligomer of alkoxysilane of 10 mer or less, a catalyst, and water are added and reacted, and the obtained reaction product is 150 ° C. or higher and And a heat treatment step of heat treatment at a temperature of less than 600 ° C. Therefore, it is possible to produce silicon oxide-coated zinc oxide capable of suppressing elution of zinc ions from the zinc oxide particles.

According to the silicon oxide-coated zinc oxide-containing composition of the present embodiment, since the silicon oxide-coated zinc oxide of the present embodiment and a solvent were contained, the zinc element contained in the silicon oxide-coated zinc oxide was externally converted into zinc ions. It is possible to suppress elution. Accordingly, it is possible to suppress deterioration in performance as a composition due to elution of zinc ions, discoloration, increase and decrease in viscosity, and the like.
In this silicon oxide-coated zinc oxide-containing composition, since elution of zinc ions is suppressed, an aqueous dispersion, an oil-in-water (O / W type) dispersion, a water-in-oil (W / O) dispersion, It can be suitably used for cosmetics such as a multilayer type (W / O / W type or O / W / O) dispersion, particularly a sunscreen. Moreover, when it applies to resin films, such as polyester and polyamide, it can be used suitably also as an ultraviolet shielding agent of a resin film.
Furthermore, since this silicon oxide-coated zinc oxide-containing composition can be mixed with a carbomer or a carbomer aqueous solution, it is possible to provide a water-soluble composition or a water-insoluble composition excellent in feeling of use.

  According to the cosmetic of this embodiment, since either or both of the silicon oxide-coated zinc oxide of this embodiment and the silicon oxide-coated zinc oxide-containing composition of this embodiment are contained in the base, zinc ions Can be prevented from eluting outward. Accordingly, it is possible to suppress deterioration in performance as a cosmetic due to elution of zinc ions, discoloration, increase / decrease in viscosity, and the like.

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

A. Silicon oxide coated zinc oxide [Example 1]
Zinc oxide particles (average particle size 250 nm; manufactured by Sumitomo Osaka Cement) and methanol were mixed and then ultrasonically dispersed to prepare a zinc oxide methanol suspension having a zinc oxide content of 20% by mass.
Next, in this zinc oxide methanol suspension, methyl silicate 51 (manufactured by Colcoat Co.) and methanol so as to be 30% by mass in terms of silicon oxide with respect to the zinc oxide particles in this zinc oxide methanol suspension, Mixed with water. Next, 1N hydrochloric acid was added to the mixture to prepare a mixture.
The content of zinc oxide in this mixed solution was 10% by mass, and the molar ratio of methyl silicate 51, pure water and hydrochloric acid was 1: 10: 0.1.

Subsequently, this mixed liquid was heated to 60 ° C. and kept at this temperature for 3 hours to be reacted.
After the reaction, solid-liquid separation was performed by centrifugation, and the obtained solid reaction product was dried at 120 ° C. to obtain a product.
Next, this product was heat-treated at 500 ° C. for 2 hours to obtain silicon oxide-coated zinc oxide of Example 1.

[Example 2]
The silicon oxide coating of Example 2 according to Example 1 except that the addition amount of methyl silicate 51 (manufactured by Colcoat Co.) was 10% by mass in terms of silicon oxide with respect to the zinc oxide particles. Zinc oxide was obtained.

[Comparative Example 1]
Zinc oxide particles (average particle size 250 nm; manufactured by Sumitomo Osaka Cement) and water were mixed and then ultrasonically dispersed to prepare a zinc oxide aqueous suspension having a zinc oxide content of 20 mass%.
Next, this zinc oxide aqueous suspension is added to a 5 mass% sodium silicate aqueous solution in terms of silicon oxide with respect to the mass of zinc oxide particles in the zinc oxide aqueous suspension and stirred vigorously. An acid soda suspension was obtained.
Next, this zinc oxide sodium silicate suspension was heated to 60 ° C., and then dilute hydrochloric acid was gradually added to the suspension to adjust the pH to 6.5-7. Thereafter, the suspension was allowed to stand for 2 hours, the suspension was subjected to solid-liquid separation, and the resulting solid was washed with water. This solid was heat-treated at 150 ° C. for 12 hours to obtain silicon oxide-coated zinc oxide of Comparative Example 1.

[Comparative Example 2]
The silicon oxide-coated zinc oxide of Comparative Example 2 is obtained in the same manner as in Comparative Example 1 except that the amount of the sodium silicate aqueous solution of Comparative Example 1 is 15% by mass in terms of silicon oxide with respect to the mass of the zinc oxide particles. It was.

[Evaluation]
The silicon oxide-coated zinc oxide in each of Examples 1-2 and Comparative Examples 1-2 was evaluated. The evaluation items are as follows.
(1) Infrared spectroscopy (IR)
IR evaluation of silicon oxide-coated zinc oxide was performed by the KBr method using JASCO FT / IR-670 Plus (manufactured by JASCO Corporation). Here, “1000” indicates that absorption bands derived from Si—O—Si stretching and absorption bands derived from zinc oxide were observed at 1000 to 1200 cm ⁻¹ and 400 to 600 cm ⁻¹ , respectively. Those in which either one or both were not observed were marked with “x”.

(2) Condensation degree of silicon oxide The silicon oxide-coated zinc oxide was measured for NMR spectrum by solid ²⁹ Si MAS-nuclear magnetic resonance (NMR) spectroscopy, and Q ⁰ , Q ¹ , Q were determined from the peak area ratio of this NMR spectrum. ^{2, Q} 3, the area ratio of ^{Q 4} signals attributable to each environment ^{Q 0, Q 1,} were calculated ^{Q 2, Q 3, Q 4} .

(3) Zinc elution rate Disperse silicon oxide-coated zinc oxide in a buffer solution of pH = 5 so as to be 0.05% by mass and stir for 1 hour, then perform solid-liquid separation, and adjust the zinc concentration in the liquid phase to ICP. Measured with an emission spectrometer.
And the ratio of zinc ion (mol) eluted in said liquid phase among zinc content (mol) in silicon oxide coating zinc oxide was made into the zinc elution rate (%).
The buffer solution of pH = 5 was prepared by mixing 500 ml of a 0.1 M potassium hydrogen phthalate aqueous solution and 226 ml of a 0.1 M sodium hydroxide aqueous solution, and then adding water to make a total volume of 1000 ml.
These evaluation results are shown in Tables 1 and 2.
Table 2 shows the measurement results of the zinc elution rate of the zinc oxide particles (average particle size 250 nm; manufactured by Sumitomo Osaka Cement) used in Example 1 as Comparative Example 3.

According to Table 2, the silicon oxide-coated zinc oxide of Examples 1 and 2 has a Q ³ + Q ⁴ value and a Q ⁴ / which indicate the degree of condensation of silicon oxide as compared with the silicon oxide-coated zinc oxide of Comparative Examples 1 and 2. It was confirmed that (Q ³ + Q ⁴ ) value was high and zinc elution rate was low.

B. Silicon oxide-coated zinc oxide-containing composition [Example 3]
Carbomer Ultrez 10 (manufactured by Nikko Chemicals Co., Ltd.) 1.5 g was dissolved in pure water, then 10% by mass aqueous sodium hydroxide solution was added dropwise to adjust the pH, and 1.5% by mass of carbomer was contained and the pH was 7.5. A carbomer aqueous solution was prepared.
Next, the carbomer aqueous solution and the silicon oxide-coated zinc oxide obtained according to Example 1 were mixed at a mass ratio of 95: 5, and then stirred, and the silicon oxide-coated zinc oxide-containing composition of Example 3 was mixed. Got.

The viscosity of this composition was 10.4 Pa · s as a result of measurement using a viscometer BII viscometer (manufactured by Toki Sangyo Co., Ltd.) at 20 ° C. and 30 rpm.
A predetermined amount was collected from the composition, and the collected sample was kept at 40 ° C. using a thermostatic bath, and the viscosity was measured every predetermined time under the conditions of 20 ° C. and 30 rpm. This change in viscosity over time is shown in FIG.

[Comparative Example 4]
The oxidation of Comparative Example 4 was performed in accordance with Example 3 except that zinc oxide particles (average particle size 250 nm; manufactured by Sumitomo Osaka Cement) were used instead of using the silicon oxide-coated zinc oxide obtained according to Example 1. A zinc-containing composition was obtained.
The viscosity of this composition was measured according to Example 3 and found to be 2.4 Pa · s.

[Comparative Example 5]
Carbomer Ultrez 10 (manufactured by Nikko Chemicals Co., Ltd.) 1.5 g was dissolved in pure water, then 10% by mass aqueous sodium hydroxide solution was added dropwise to adjust the pH, and 1.5% by mass of carbomer was contained and the pH was 7.5. A carbomer aqueous solution was prepared.
Next, the carbomer aqueous solution and pure water were mixed at a mass ratio of 95: 5 and then stirred to obtain a carbomer aqueous solution of Comparative Example 5.

Next, the viscosity of the carbomer aqueous solution was measured according to Example 3, and as a result, it was 9.5 Pa · s.
A predetermined amount was collected from the carbomer aqueous solution, and the collected sample was kept at 40 ° C. using a thermostatic bath, and the viscosity was measured at 20 ° C. and 30 rpm every predetermined time. This change in viscosity over time is shown in FIG.

According to the above results, the silicon oxide-coated zinc oxide-containing composition of Example 3 has a sufficiently suppressed zinc elution rate, and the viscosity decreases until about 15 hours after the composition is produced. It was confirmed that the subsequent viscosity was constant and the decrease in viscosity was suppressed.
In addition, the viscosity became a little lower at first due to the change with time, but after a certain time or more, the viscosity after that became almost constant, and it was confirmed that the decrease in viscosity was suppressed.

On the other hand, the composition of Comparative Example 4 was confirmed to have a high zinc elution rate because the surface of zinc oxide was not coated with a silicon oxide film, and that the viscosity immediately decreased after the composition was prepared. .
In Comparative Example 5, since the carbomer aqueous solution did not contain zinc oxide, it was not affected by heating and holding at 40 ° C., and the viscosity was constant at about 10 Pa · s.

The silicon oxide-coated zinc oxide of the present invention has an average particle diameter of zinc oxide particles exceeding 50 nm and not more than 500 nm in the silicon oxide-coated zinc oxide obtained by coating the surface of zinc oxide particles with a silicon oxide film. when the existence ratio in the ^{Q 3} environments of silicon was the presence ratio in ^Q 3, ^{Q 4} environment ^{Q 4,} and the ^Q 3 + Q ⁴ ≧ 0.6 and ^{Q 4 / (Q 3 + Q} 4) ≧ 0.5 By suppressing the elution of zinc ions from the zinc oxide particles to the outside, when this silicon oxide-coated zinc oxide is applied to cosmetics, the performance, discoloration, discoloration, When it is used in fields other than cosmetics as well as being applied to cosmetics with excellent usability because it can control the increase and decrease of viscosity etc. Information, the range of selection of the dispersing agent and the resin spreads, it is possible to increase the degree of freedom in designing the formulation of paints, a large industrial value.

Claims (6)

Zinc oxide particles, the surfaces of the zinc oxide particles a silicon oxide-coated zinc oxide with a silicon oxide film formed by overturned be,
The average particle diameter of the zinc oxide particles is more than 50 nm and not more than 500 nm,
When the presence ratio of the presence ratio in the solid ²⁹ Si MAS- nuclear magnetic resonance (NMR) ^{Q 3} environments of silicon of the silicon oxide in the film was measured by spectroscopy at ^Q 3, ^{Q 4} environment was ^{Q 4, Q} 3 + ^Q Silicon oxide-coated zinc oxide, wherein ⁴ ≧ 0.6 and Q ⁴ / (Q ³ + Q ⁴ ) ≧ 0.5.   The silicon oxide-coated zinc oxide according to claim 1, wherein the content of the zinc oxide particles is 50% by mass or more and 99% by mass or less.   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, the elution rate of zinc eluted in the aqueous solution is 60% by mass or less. The silicon oxide-coated zinc oxide according to claim 1 or 2. Zinc oxide particles having an average particle diameter of more than 50 nm and 500 nm or less are suspended in a solvent to obtain a zinc oxide suspension,
Next, this zinc oxide suspension is reacted by adding one or more of alkoxysilane and oligomers of alkoxysilane of 10-mer or less, a catalyst, and water,
Next, a method for producing a silicon oxide-coated zinc oxide, comprising heat-treating the obtained reaction product at a temperature of 250 ° C. or higher and lower than 600 ° C.   A silicon oxide-coated zinc oxide-containing composition comprising the silicon oxide-coated zinc oxide according to any one of claims 1 to 3 and a solvent.   It contains either or both of the silicon oxide-coated zinc oxide according to any one of claims 1 to 3 and the silicon oxide-coated zinc oxide-containing composition according to claim 5 in a base. And cosmetics.

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