JP2014084448A - Ultraviolet-shielding composite particles, dispersion including ultraviolet-shielding composite particles and cosmetic - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide ultraviolet-shielding composite particles capable of inhibiting elution of zinc ions from zinc oxide particles; a dispersion including the ultraviolet-shielding composite particles; and a cosmetic.SOLUTION: The ultraviolet-shielding composite particles 1 of the present invention comprise: a core material portion 2 including zinc oxide and a first resin; and a coating film 3 formed on the surface 2a of this core material portion 2 and consisting of a second resin having a composition identical to or different from the composition of the first resin.

Description

  The present invention relates to an ultraviolet shielding composite particle, an ultraviolet shielding composite particle-containing dispersion, and a cosmetic, and more specifically, is suitably used for a film, a pigment, a paint, a cosmetic, an ultraviolet shielding material, an optical material, and an electronic material. UV-shielding composite particles suitable for use in skin lotions, sunscreen gels, emulsions, creams, foundations, lipsticks, blushers, eye shadows, and the like, and UV-shielding composite particle-containing dispersions and cosmetics that require UV shielding function is there.

In addition to visible light, light includes light of various wavelengths such as near infrared, far infrared, and ultraviolet light.
In particular, ultraviolet rays have a wavelength region from the UV-A region (320-340 nm) to the UV-B region (280-320 nm). By breaking molecular bonds, many substances such as resins and rubbers can be obtained. It is a cause of deterioration. In addition, it is known that ultraviolet rays can cause not only suntan and sunburn but also aging and skin cancer. Therefore, ultraviolet shielding agents are widely used in various fields such as films, pigments, paints, and cosmetics.

The ultraviolet shielding agent is roughly classified into an inorganic ultraviolet shielding agent and an organic ultraviolet shielding agent. Organic UV-screening agents are safer due to deterioration due to heat and long-term UV irradiation, inability to absorb UV in a wide wavelength range, and skin irritation problems. There is a need for UV screening agents. On the other hand, an inorganic ultraviolet shielding agent is excellent in heat resistance and weather resistance because it is not deteriorated by heat or prolonged ultraviolet irradiation. As the inorganic ultraviolet shielding agent, titanium oxide and zinc oxide are generally used.
In particular, zinc oxide can block ultraviolet rays in a wide wavelength range from the UV-A region (320-340 nm) to the UV-B region (280-320 nm). Moreover, since zinc oxide has a lower refractive index (refractive index 2.0) than titanium oxide (refractive index 2.7), it is used as an ultraviolet shielding agent having excellent transparency when it is made into nanoparticles.
On the other hand, since zinc is an amphoteric element, zinc oxide, which is an oxide thereof, has a problem of stability in that it easily dissolves in acid and alkali, dissolves in a small amount in water, and releases zinc ions.

For example, in the case of cosmetics, water-based cosmetics and oil-based cosmetics have been proposed and put to practical use. Water-based cosmetics are less sticky than oil-based cosmetics and provide a smooth feeling of use. In recent years, it has been particularly used as various cosmetics such as sunscreens, emulsions and creams.
When zinc oxide is used in these water-based cosmetics, the zinc ions eluted in the cosmetics react with organic UV screening agents, water-soluble polymers (thickeners, etc.), etc., resulting in performance degradation, discoloration, and makeup. Since there is a problem of increasing or decreasing the viscosity of the material, 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 eluted carbomer reacts with the carboxylic acid part of the carbomer, thereby destroying the gel structure of the carbomer and lowering the viscosity. There is a problem of doing.

  Therefore, in order to solve these problems, zinc oxide is coated with an inorganic compound to suppress elution of zinc ions, and a high-density coating layer made of hydrous silicon oxide is formed on the surface of zinc oxide particles. Proposed zinc oxide particle composition (Patent Document 1) and silica-coated fine particle zinc oxide (Patent Document 2) in which a water-containing silica layer having a two-layer structure is formed on the surface of a substrate made of zinc oxide particles.

On the other hand, a spherical resin powder containing zinc oxide has been proposed as zinc oxide encapsulated in resin particles (Patent Document 3).
In this spherical resin powder, a spherical resin powder is prepared using a dispersion having a dispersed particle diameter of zinc oxide of 0.1 μm or less, and the obtained spherical resin powder has a particle diameter of 30 μm or less and zinc oxide. Is contained in 1 to 80% by weight of the total weight, so that secondary aggregation of the zinc oxide particles can be suppressed, and it can be used as a cosmetic raw material excellent in transparency and feeling of use. .
Furthermore, composite spherical polymer particles in which zinc oxide particles having a primary particle size of 0.1 μm or less are uniformly dispersed in an acrylic resin have been proposed (Patent Document 4).

Japanese Patent No. 3520785 Japanese Patent No. 4836232 Japanese Patent No. 3469641 JP 2010-215554 A

However, the zinc oxide particle composition described in Patent Document 1 and the silica-coated fine particle zinc oxide described in Patent Document 2 have low dispersibility with respect to the base just by coating the zinc oxide particles with an inorganic compound, and feel to the skin. There was a problem that (use feeling) deteriorated. Therefore, when zinc oxide particles are coated with an inorganic compound in this way, it is necessary to coat with a polymer or the like separately in order to improve the feeling of use, and there is a new problem that the cost increases.
On the other hand, the spherical resin powder containing zinc oxide described in Patent Document 3 and the composite spherical polymer particles described in Patent Document 4 can suppress secondary aggregation of the zinc oxide particles, but zinc from the zinc oxide particles can be suppressed. Since it is not intended to suppress ion elution, the suppression of zinc ion elution from zinc oxide particles into the base is insufficient, resulting in poor cosmetic performance, discoloration, and viscosity of cosmetics due to zinc ion elution. There was a problem that problems such as increase / decrease occurred.

  The present invention has been made in view of the above circumstances, and provides an ultraviolet shielding composite particle capable of suppressing elution of zinc ions from zinc oxide particles, an ultraviolet shielding composite particle-containing dispersion, and a cosmetic. The purpose is to do.

  As a result of intensive studies in order to solve the above problems, the present inventors have found that the surface of the core part that becomes the core containing zinc oxide and the first resin is the same as the first resin. If a coating film serving as a shell made of a second resin having a different composition or composition is formed, composite particles having a so-called core-shell structure are formed, and this coating film contains a core material portion containing zinc oxide and the first resin. That the elution of zinc ions from water can be prevented, and if this ultraviolet shielding composite particle is applied to cosmetics, it is found that the ultraviolet shielding function is improved and the transparency is excellent, and the present invention is completed. It came to do.

  That is, the ultraviolet shielding composite particle of the present invention has a core material portion containing zinc oxide and the first resin, and the same or different composition as the first resin formed on the surface of the core material portion. And a coating film made of a second resin.

It is preferable that the content rate of the said zinc oxide is 15 mass% or more and 40 mass% or less with respect to the total mass containing the said core material part and the said coating film.
The mass of the coating film is preferably 30% by mass or more and 70% by mass or less of the total mass including the coating film and the core material part.
The coating film preferably contains an organic ultraviolet absorber.

  The dispersion containing ultraviolet shielding composite particles of the present invention is characterized in that the ultraviolet shielding composite particles of the present invention are dispersed in a dispersion medium.

  The cosmetic of the present invention is characterized in that either or both of the ultraviolet shielding composite particles of the present invention and the ultraviolet shielding composite particle-containing dispersion of the present invention are contained in a base.

  According to the ultraviolet shielding composite particle of the present invention, a core material portion containing zinc oxide and the first resin, and the same or different composition as the first resin formed on the surface of the core material portion. Since the coating film made of the second resin is provided, the coating film suppresses the elution of zinc ions from the zinc oxide contained in the core material portion, so that the zinc oxide contained in the composite particle It is possible to prevent zinc ions 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 of the cosmetic, and the like.

  According to the dispersion containing ultraviolet shielding composite particles of the present invention, since the ultraviolet shielding composite particles of the present invention are dispersed in the dispersion medium, zinc ions are eluted from the zinc oxide contained in the ultraviolet shielding composite particles. Can be suppressed. Accordingly, it is possible to suppress deterioration in performance as a cosmetic due to elution of zinc ions, discoloration, increase / decrease in viscosity of the cosmetic, and the like.

  According to the cosmetic of the present invention, since either or both of the ultraviolet shielding composite particles of the present invention and the dispersion containing the ultraviolet shielding composite particles of the present invention are contained in the base, the ultraviolet shielding composite particles or It can suppress that zinc ion elutes in a base from the zinc oxide contained in the dispersion liquid. Accordingly, it is possible to suppress deterioration in performance as a cosmetic due to elution of zinc ions, discoloration, increase / decrease in viscosity of the cosmetic, and the like.

It is sectional drawing which shows an example of the ultraviolet-ray shielding composite particle of one Embodiment of this invention.

An embodiment for carrying out the ultraviolet shielding composite particles, the ultraviolet shielding composite particle-containing dispersion, and the cosmetic of the present invention will be described.
The following embodiments are specifically described for better understanding of the gist of the invention, and do not limit the present invention unless otherwise specified.

[Ultraviolet shielding composite particles]
An ultraviolet shielding composite particle according to an embodiment of the present invention (hereinafter sometimes simply referred to as “composite particle”) includes a core part containing zinc oxide and a first resin, A composite particle including a coating film formed on the surface and made of a second resin having the same composition as or different from the first resin.

FIG. 1 is a cross-sectional view showing an example of the ultraviolet shielding composite particle of the present embodiment. The ultraviolet shielding composite particle 1 is the entire surface 2a of the core portion 2 containing zinc oxide and the first resin. In addition, a coating film 3 made of a second resin having the same composition as or different from the first resin is formed.
The shape of the core portion 2 can be appropriately selected from various shapes such as an oval shape, a plate shape, and a lens shape in addition to a spherical cross section shown in FIG. In addition, since the coating film 3 is intended to suppress the elution of zinc ions from the zinc oxide contained in the core part 2 to the outside, it is necessary to cover the entire surface 2 a of the core part 2. There is.

  The content of zinc oxide in the total mass of the composite particle 1 is preferably 15% by mass or more and 40% by mass or less. Here, when the content of zinc oxide in the composite particles 1 is less than 15% by mass, a desired ultraviolet shielding effect cannot be obtained. On the other hand, when the content of zinc oxide exceeds 40% by mass, the ratio of zinc oxide in the core part 2 containing zinc oxide and resin becomes too high, and the predetermined shape is not obtained. Since it becomes difficult to produce the core part 2, it is not preferable.

The average particle size of the composite particles 1 is preferably 50 nm or more and 1 μm or less, more preferably 100 nm or more and 700 nm or less, and further preferably 100 nm or more and 500 nm or less.
Here, the reason why the average particle size of the composite particle 1 is limited to the above range is that when the average particle size is less than 50 nm, the particle size is too small, so that the synthesis of the composite particle 1 becomes difficult. If the average particle diameter exceeds 1 μm, the composite particles 1 may be easily settled when the composite particles 1 are dispersed in a dispersion medium to form a dispersion containing ultraviolet shielding composite particles. This is because when 1 is used for a dispersant, a resin film, a cosmetic, or the like, the transparency in the visible light region may be impaired.

  As used herein, “average particle diameter” refers to a predetermined number, for example, 500 or 100 of the composite particles 1, and the longest straight portion (maximum long diameter) of each of the composite particles 1 is measured. It is a numerical value obtained by weighted average of these measured values.

Hereinafter, each component of the ultraviolet shielding composite particle of the present embodiment will be described in detail.
"Core part 2"
The core member 2 contains zinc oxide and a first resin.
The content of zinc oxide in the core member 2 is preferably 30% by mass or more and 80% by mass or less. Here, when the content of zinc oxide is less than 30% by mass, the content of zinc oxide in the composite particle 1 in the case of the composite particle 1 may be reduced to lower than 15% by mass, and the desired ultraviolet shielding performance. This is because it may be necessary to use a large amount of the composite particles 1 to obtain the zinc oxide. On the other hand, if the zinc oxide content exceeds 80% by mass, the amount of the zinc oxide in the core member 2 is too large. This is because it may be difficult to manufacture the core part 2.

  The core member 2 may contain a slight amount of other metal oxides such as zirconium oxide, titanium oxide, tin oxide, cerium oxide, and the like within a range not impairing the ultraviolet shielding performance of zinc oxide.

The average particle diameter of the core material part 2 may be appropriately adjusted according to the application, and is not particularly limited.
For example, when used for transparent cosmetics, it is preferably 40 nm or more and 900 nm or less, more preferably 50 nm or more and 600 nm or less, and further preferably 50 nm or more and 450 nm or less.
Here, the reason why the average particle diameter of the core material part 2 is limited to the above range is that this range is a range in which the core material part 2 having a stable shape can be easily obtained. Since there is a possibility that the core part 2 in which zinc oxide and the first resin are uniformly distributed cannot be obtained, it is not preferable.

(First resin)
The first resin constituting the core part 2 may be appropriately selected depending on the application, and is not particularly limited. For example, (meth) acrylic resin, acrylic ester, methacrylic ester, acrylic styrene copolymer , Acrylic polyester copolymer, silicon acrylic copolymer and the like. Among these resins, a (meth) acrylic resin is particularly preferable because of its excellent transparency.

Examples of this (meth) acrylic resin monomer include methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, hexyl acrylate, octyl acrylate, nonyl acrylate, decyl acrylate, lauryl acrylate, acrylic acid Alkyl acrylates such as stearyl and dodecyl acrylate;
Methacrylic acid alkyl esters such as methyl methacrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate, hexyl methacrylate, octyl methacrylate, nonyl methacrylate, decyl methacrylate, lauryl methacrylate, stearyl methacrylate, dodecyl methacrylate ;
Acrylic acid, methacrylic acid;
Mention may be made of acrylonitrile; methacrylonitrile; 2-chloroethyl acrylate; phenyl acrylate; trifluoroethyl acrylate; tetrafluoropropyl acrylate.

Examples of monomers that can be polymerized in combination with these (meth) acrylic resin monomers include styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, α-methylstyrene, o-ethylstyrene. , M-ethylstyrene, p-ethylstyrene, 2,4-dimethylstyrene, pn-butylstyrene, pt-butylstyrene, pn-hexylstyrene, pn-octylstyrene, pn- Nonyl styrene, pn-decyl styrene, pn-dodecyl styrene, p-methoxy styrene, p-phenyl styrene, p-chloro styrene, 3,4-dichloro styrene, vinyl acetate, vinyl propionate, vinyl benzoate, Vinyl acetate, N-vinylvinylvinyl, vinylidene fluoride, tetrafluoroethylene, hex Hexafluoropropylene, butadiene, it may be mentioned Isoburen.
The monomers described above may be polymerized alone or in combination of two or more. Further, an oligomer may be appropriately used instead of the above-described monomer.

"Coating film 3"
The coating film 3 is a coating film made of a second resin having the same composition as or different from the first resin.
The second resin constituting the coating film 3 is, for example, (meth) acrylic resin, acrylic ester, methacrylic ester, acrylic styrene copolymer, acrylic polyester copolymer, as with the first resin. Examples thereof include a coalescence and a silicon acrylic copolymer. Among these resins, a (meth) acrylic resin is particularly preferable because of its excellent transparency. Since the (meth) acrylic resin monomer and the monomer that can be polymerized in combination with these (meth) acrylic resin monomers have already been described, they are omitted here.

  The second resin may be appropriately selected depending on the application, and may be the same composition as the first resin or a different composition. In consideration of adhesion, a resin having the same composition as the first resin used for the core member 2 is preferable. For example, when the first resin is a (meth) acrylic resin, the second resin is also preferably a (meth) acrylic resin.

The coating film 3 may contain an organic ultraviolet absorber or the like as long as the characteristics are not impaired.
Examples of organic ultraviolet absorbers include dibenzoylmethane derivatives (dibenzoylmethane and derivatives thereof), benzophenone derivatives (benzophenone and derivatives thereof), paraaminobenzoic acid derivatives (paraaminobenzoic acid and derivatives thereof), methoxycinnamic acid derivatives ( Methoxycinnamic acid and derivatives thereof), benzotriazole derivatives (benzotriazole and derivatives thereof), cyanoacrylate derivatives (cyanoacrylate and derivatives thereof), salicylic acid derivatives (salicylic acid and derivatives thereof), and the like can be used. These organic ultraviolet absorbers may be used alone or in combination of two or more.

The higher the content of the dibenzoylmethane derivative, the higher the efficiency of ultraviolet absorption per unit dibenzoylmethane derivative.
Therefore, if a dibenzoylmethane derivative is added to the coating film 3, the dibenzoylmethane derivative is present only in the coating film 3 covering the core part 2. Compared with the case where the dibenzoylmethane derivative added to the coating film 3 is simply mixed with the ultraviolet shielding composite particle 1, the ultraviolet absorption spectrum of the coating film 3 containing the dibenzoylmethane derivative is broadened. Absorption to the long wavelength side is possible. As a result, the ultraviolet absorption efficiency per unit of the coating film 3 containing the dibenzoylmethane derivative is increased, and the ultraviolet absorption is improved.

Among these dibenzoylmethane derivatives, 4-tert-butyl-4′-methoxydibenzoylmethane (Avobenzone) is particularly preferable from the viewpoint of ultraviolet shielding properties and transparency.
Also, not only dibenzoylmethane derivatives but also other organic UV screening agents such as benzophenone derivatives, paraaminobenzoic acid derivatives, methoxycinnamic acid derivatives, salicylic acid derivatives, etc., as long as the properties are not impaired. May be used.

The total mass of the coating film 3 is 30% by mass or more and 70% by mass or less based on the total mass of the composite particles 1, that is, the total mass of the mass of the core member 2 and the mass of the coating film 3. More preferably, it is 40 mass% or more and 65 mass% or less.
Here, the reason why the total mass of the coating film 3 is in the above range with respect to the total mass of the composite particle 1 is that the total mass of the coating film 3 is less than 40% by mass with respect to the total mass of the composite particle 1. Then, it becomes difficult to form the coating film 3 uniformly on the surface 2a of the core part 2, and a part of the surface 2a of the core part 2 is exposed or the film thickness of the coating film 3 is sufficiently increased. As a result, it may be difficult to ensure sufficient elution of zinc ions. On the other hand, when the total mass of the coating film 3 exceeds 70% by mass with respect to the total mass of the composite particles 1, the content of zinc oxide in the composite particles 1 decreases, and as a result, a desired ultraviolet shielding effect is obtained. There is a possibility that a large amount of the composite particles 1 need to be used.

[Method for producing ultraviolet shielding composite particles]
In the manufacturing method of the ultraviolet shielding composite particle 1 of the present embodiment, a core material part manufacturing step for manufacturing the core material part 2 and a coating film 3 made of a second resin are formed on the surface 2 a of the core material part 2. A coating film forming step.

"Core material production process"
The method for producing the core part 2 is not particularly limited. For example, a dispersion obtained by dispersing the above-described zinc oxide fine particles in the above-described first resin monomer by a known method is used by using a known polymerization method. What is necessary is just to pulverize and make the core part 2. As such a polymerization method, for example, a miniemulsion method or the like is preferably used.

"Coating film formation process"
In this step, the second resin monomer is polymerized in the presence of the core part 2 to form a coating film 3 made of the second resin on the surface 2a of the core part 2, As a method for polymerizing the resin monomer, a known method may be used, and it is not particularly limited. Examples of such a polymerization method include a seed polymerization method and a mini-emulsion method. In particular, a seed polymerization method is preferably used.

[Dispersion containing ultraviolet shielding composite particles]
The ultraviolet shielding composite particle-containing dispersion of the present embodiment (hereinafter sometimes simply referred to as “dispersion”) is a dispersion obtained by dispersing the ultraviolet shielding composite particles 1 in a dispersion medium.
The content of the composite particles 1 in this dispersion may be adjusted as appropriate in order to obtain the desired ultraviolet shielding performance, preferably 1% by mass to 80% by mass, more preferably 20% by mass to 70% by mass. Hereinafter, it is more preferably 30% by mass or more and 60% by mass or less.

  Here, the reason why the content of the composite particles 1 is 1% by mass or more and 80% by mass or less is that when the content of the composite particles 1 is less than 1% by mass, the dispersion exhibits a sufficient ultraviolet shielding function. This is because there is a risk that it will not be possible. Therefore, it is necessary to add a large amount of dispersion when blended in cosmetics and the like, which may increase the cost. On the other hand, if the content exceeds 80% by mass, the viscosity of the dispersion increases (thickens), the dispersion stability of the composite particles 1 decreases, and the composite particles 1 may easily settle.

Such a dispersion medium is not particularly limited as long as it is a solvent that can disperse the composite particles 1 described above, but in addition to water, methanol, ethanol, 1-propanol, 2-propanol, 1-butanol. Alcohols such as 2-butanol and octanol;
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;
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.
Only 1 type may be used among these water and a solvent, and 2 or more types may be mixed and used for it.

The dispersion of this embodiment may contain a dispersant and a water-soluble binder as long as the characteristics are not impaired.
As the dispersant, anionic surfactants, cationic surfactants, amphoteric surfactants, nonionic surfactants, and silane coupling agents such as organoalkoxysilanes and organochlorosilanes are preferably used. The type and amount of these dispersants may be appropriately selected depending on the particle diameter of the composite particles 1 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 mixed. May be used.
As the water-soluble binder, polyvinyl alcohol (PVA), polyvinyl pyrrolidone, hydroxycellulose, polyacrylic acid, or the like can be used.

  The method for dispersing the composite particles 1 in the dispersion medium is not particularly limited, and 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 sufficient as long as the composite particles 1 are uniformly dispersed in the dispersion medium.

[Cosmetics]
The cosmetic of the present embodiment contains either or both of the ultraviolet shielding composite particles 1 and the ultraviolet shielding composite particle-containing dispersion in the base.
When these ultraviolet shielding composite particles 1 and the dispersion containing ultraviolet shielding composite particles are used for ultraviolet shielding applications, it is preferable to use those having an average particle diameter of 50 nm or more and 700 nm or less. .
The content of the composite particle 1 may be adjusted as appropriate, but it is preferably 1% by mass to 60% by mass with respect to the total mass of the cosmetic. By containing the composite particles 1 within the above range, a sufficient transparency can be secured, and there can be obtained a cosmetic material that has no roughness and has a good feeling of use.

The cosmetic of the present embodiment may contain an organic ultraviolet shielding agent, an inorganic ultraviolet shielding agent, an additive and the like within a range not impairing the effects of the present invention.
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.

  Examples of the inorganic ultraviolet shielding agent include titanium oxide, zinc oxide, cerium oxide, and the like, and one or two or more kinds can be appropriately selected from these groups.

In this cosmetic, any one or both of the ultraviolet shielding composite particles 1 and the dispersion containing the ultraviolet shielding composite particles are placed in a base such as an emulsion, cream, foundation, lipstick, blusher, eye shadow, or the like. It can be obtained by blending as usual.
In addition, one or both of the above-described UV-shielding composite particles 1 and the above-mentioned UV-shielding composite particle-containing dispersion are blended with water-based cosmetics such as lotions and sunscreen gels, which have been difficult to formulate in the past. 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 ultraviolet shielding composite particle 1 of the present embodiment, the core material portion 2 containing zinc oxide and the first resin, and the surface 2a of the core material portion 2 are formed on the surface 2a. Since the coating film 3 made of the second resin having the same composition as or a different composition from the resin 1 is provided, the coating film 3 suppresses the elution of zinc ions from the zinc oxide contained in the core member 2. By doing so, it is possible to prevent zinc ions from eluting from the zinc oxide contained in the composite particle 1 and diffusing outward of the composite particle 1. Accordingly, it is possible to suppress deterioration in performance as a cosmetic due to elution of zinc ions, discoloration, increase / decrease in viscosity of the cosmetic, and the like.

In the case where the coating film 3 contains an organic ultraviolet absorber, the UV-A region has a UV effect due to a synergistic effect between the absorption performance of the organic ultraviolet absorber and the scattering performance of zinc oxide in the core portion 2. The shielding property of ultraviolet rays in a wide wavelength range up to -B region can be improved.
In particular, when a dibenzoylmethane derivative is used as the organic ultraviolet absorber, the ultraviolet absorption performance can be further improved.

  According to the dispersion containing ultraviolet shielding composite particles of the present embodiment, since the ultraviolet shielding composite particles 1 of the present embodiment are dispersed in the dispersion medium, zinc ions are dispersed from the zinc oxide contained in the ultraviolet shielding composite particles 1. Elution into the inside can be suppressed. Therefore, it is possible to improve the shielding property of ultraviolet rays in a wide wavelength range from the UV-A region to the UV-B region in the dispersion.

  According to the cosmetic of the present embodiment, since either or both of the ultraviolet shielding composite particles 1 of the present embodiment and the ultraviolet shielding composite particle-containing dispersion of the present embodiment are contained in the base, the ultraviolet rays are contained. It is possible to suppress the elution of zinc ions from the zinc oxide contained in the shielding composite particles 1 or the dispersion thereof into the base. Accordingly, it is possible to suppress deterioration in performance as a cosmetic due to elution of zinc ions, discoloration, increase / decrease in viscosity of the cosmetic, and the like.

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

[Example 1]
"Preparation of UV shielding composite particles"
A. Production of core material part 55 parts by mass of zinc oxide particles (manufactured by Sumitomo Osaka Cement) having an average primary particle size of 0.02 μm, 3.3 parts by mass of a phosphate type surfactant, methyl methacrylate (hereinafter abbreviated as MMA) 41.7 parts by mass were mixed and subjected to a dispersion treatment at 2500 rpm for 2 hours in a bead mill using zirconia beads to prepare a zinc oxide / MMA dispersion.
When the volume particle size distribution of the obtained dispersion was evaluated with a particle size distribution analyzer LB-550 (manufactured by Horiba Seisakusho), the particle size at a cumulative volume percentage of 10% by volume (d10) was 54 nm, and the cumulative volume percentage was 50 volumes. % (D50) had a particle size of 87 nm, and a cumulative volume percentage of 90 vol% (d90) had a particle size of 160 nm.

  Next, 30.00 parts by mass of the above zinc oxide / MMA dispersion, 64.75 parts by mass of pure water, 0.95 parts by mass of sodium dodecylbenzenesulfonate, 4 parts by mass of ethylene glycol dimethacrylate, silicone antifoaming agent KS -66 (manufactured by Shin-Etsu Chemical Co., Ltd.) 0.30 parts by mass was mixed and stirred using a homogenizer to prepare an emulsion A.

Next, 80 parts by mass of the obtained emulsion and a potassium persulfate solution in which 0.032 parts by mass of potassium persulfate was dissolved in 19.968 parts by mass of pure water were mixed, and a reactor equipped with a stirrer and a thermometer was mixed. The nitrogen substitution was carried out at room temperature (25 ° C.) for 1 hour. Next, the temperature was raised to 65 ° C., and the polymerization reaction was carried out by holding at 65 ° C. for 3 hours to obtain slurry A containing zinc oxide-containing resin particles A serving as a core material portion.
Next, the slurry A containing the zinc oxide-containing resin particles A is subjected to solid-liquid separation with a centrifuge, and then the separated solid is washed with pure water and further dried at 90 ° C. to obtain zinc oxide. The contained resin particles A were collected.

B. Evaluation of core part The content rate of the zinc oxide in this zinc oxide containing resin particle A was measured.
Here, a thermogravimetric measuring device Thermoplus 8120 (manufactured by Rigaku Corporation) Thermoplus 8120) was performed, and the content of zinc oxide was calculated from the residue after heating at 800 ° C. As a result, the zinc oxide content in the zinc oxide-containing resin particles A was 53% by mass.

Next, the zinc elution amount of the zinc oxide-containing resin particles A was measured.
Here, the zinc oxide-containing resin particles A were immersed in dilute hydrochloric acid at pH = 2 maintained at 25 ° C., and the solubility of zinc oxide in the dilute hydrochloric acid was measured by atomic absorption analysis. As a result, the zinc elution amount of the zinc oxide-containing resin particles A was 18 ppm.

C. Preparation of UV-shielding composite particles 30 parts by mass of MMA and 69.964 parts by mass of pure water were mixed with a potassium persulfate dispersion in which 0.036 parts by mass of potassium persulfate was dissolved, and stirred and mixed with a homogenizer. Was made.
Next, 85 parts by mass of slurry A containing zinc oxide-containing resin particles A and 15 parts by mass of emulsion A were mixed, and nitrogen substitution was performed at room temperature (25 ° C.) for 1 hour. Next, the temperature is raised to 65 ° C. and held at 65 ° C. for 3 hours to conduct a polymerization reaction, and a coating made of a methacrylic resin obtained by polymerizing MMA on the surface of the zinc oxide-containing resin particles A serving as a core material portion. A film was formed.
Next, the reaction solution is subjected to solid-liquid separation with a centrifuge, and then the separated solid is washed with pure water and further dried at 90 ° C. to produce the ultraviolet shielding composite particles A of Example 1. did.

D. Evaluation of UV shielding composite particles The content of zinc oxide in the UV shielding composite particles A was measured in the same manner as the zinc oxide-containing resin particles A. As a result, the content of zinc oxide in the ultraviolet shielding composite particles A was 44% by mass.
Subsequently, the zinc elution amount of the ultraviolet shielding composite particles A was measured in the same manner as the zinc oxide-containing resin particles A. As a result, the zinc elution amount of the ultraviolet shielding composite particles A was 10 ppm.

[Example 2]
"Preparation of UV shielding composite particles"
A. Preparation of core part Oxidation of Example 2 according to Example 1 except that 55 parts by mass of zinc oxide particles (manufactured by Sumitomo Osaka Cement) having an average primary particle size of 0.02 μm were changed to 52.5 parts by mass. A zinc / MMA dispersion was prepared.
When the volume particle size distribution of the obtained dispersion was evaluated with a particle size distribution analyzer LB-550 (manufactured by Horiba Seisakusho), the particle size was 53 nm and the cumulative volume percentage was 50 volumes when the cumulative volume percentage was 10 vol% (d10). % (D50) had a particle diameter of 82 nm, and the cumulative volume percentage was 90 volume% (d90), and the particle diameter was 128 nm.

  Next, 30.00 parts by mass of the above zinc oxide / MMA dispersion, 64.75 parts by mass of pure water, 0.95 parts by mass of sodium dodecylbenzenesulfonate, 4 parts by mass of ethylene glycol dimethacrylate, silicone antifoaming agent KS -66 (manufactured by Shin-Etsu Chemical Co., Ltd.) 0.30 part by mass was mixed and stirred using a homogenizer to prepare an emulsion B.

Next, 80 parts by mass of the obtained emulsion B and a potassium persulfate solution obtained by dissolving 0.034 parts by mass of potassium persulfate in 19.966 parts by mass of pure water were mixed, and a reactor equipped with a stirrer and a thermometer was mixed. The nitrogen substitution was carried out at room temperature (25 ° C.) for 1 hour. Next, the temperature was raised to 65 ° C., and the polymerization reaction was carried out by holding at 65 ° C. for 3 hours to obtain a slurry B containing zinc oxide-containing resin particles B serving as a core material part.
Next, the slurry B containing the zinc oxide-containing resin particles B is subjected to solid-liquid separation with a centrifuge, and then the separated solid is washed with pure water and further dried at 90 ° C. to obtain zinc oxide. The contained resin particles B were collected.

B. Evaluation of Core Material Part The content rate of zinc oxide in the zinc oxide-containing resin particles B was measured according to Example 1. As a result, the zinc oxide content in the zinc oxide-containing resin particles B was 51% by mass.
Next, the zinc elution amount of the zinc oxide-containing resin particles B was measured according to Example 1. As a result, the zinc elution amount of the zinc oxide-containing resin particles B was 19 ppm.

C. Preparation of UV shielding composite particles 30 parts by mass of MMA and 69.964 parts by mass of pure water were mixed with potassium persulfate dispersion in which 0.036 parts by mass of potassium persulfate was dissolved, and stirred and mixed with a homogenizer. Was made.
Next, 80 parts by mass of the slurry B containing the zinc oxide-containing resin particles B and 15 parts by mass of the emulsion B were mixed, and nitrogen substitution was performed at room temperature (25 ° C.) for 1 hour. Next, the temperature is raised to 65 ° C. and held at 65 ° C. for 3 hours to conduct a polymerization reaction, and a coating made of a methacrylic resin obtained by polymerizing MMA on the surface of the zinc oxide-containing resin particles B serving as a core material portion A film was formed.
Next, the reaction solution is subjected to solid-liquid separation with a centrifugal separator, and then the separated solid is washed with pure water and further dried at 90 ° C. to produce the ultraviolet shielding composite particle B of Example 2. did.

D. Evaluation of UV-shielding composite particles Next, the content of zinc oxide in the UV-shielding composite particles B was measured according to Example 1. As a result, the content of zinc oxide in the ultraviolet shielding composite particle B was 39% by mass.
Subsequently, the zinc elution amount of the ultraviolet shielding composite particles B was measured according to Example 1. As a result, the zinc elution amount of the ultraviolet shielding composite particle B was 7 ppm.

[Example 3]
"Preparation of UV shielding composite particles"
A. Preparation of core material part According to Example 1, except that 55 parts by mass of zinc oxide particles (manufactured by Sumitomo Osaka Cement) having an average primary particle size of 0.02 μm were changed to 50 parts by mass, the zinc oxide / An MMA dispersion was prepared.
When the volume particle size distribution of the obtained dispersion was evaluated with a particle size distribution analyzer LB-550 (manufactured by Horiba, Ltd.), the particle diameter was 49 nm and the cumulative volume percentage was 50 volumes when the cumulative volume percentage was 10 vol% (d10). % (D50) had a particle size of 80 nm, and a cumulative volume percentage of 90 vol% (d90) had a particle size of 134 nm.

  Next, 30.00 parts by mass of the above zinc oxide / MMA dispersion, 64.75 parts by mass of pure water, 0.95 parts by mass of sodium dodecylbenzenesulfonate, 4 parts by mass of ethylene glycol dimethacrylate, silicone antifoaming agent KS -66 (manufactured by Shin-Etsu Chemical Co., Ltd.) 0.30 parts by mass was mixed and stirred using a homogenizer to prepare Emulsion C.

Next, 80 parts by mass of the obtained emulsion C and a potassium persulfate solution obtained by dissolving 0.036 parts by mass of potassium persulfate in 19.964 parts by mass of pure water were mixed, and a reactor equipped with a stirrer and a thermometer was mixed. The nitrogen substitution was carried out at room temperature (25 ° C.) for 1 hour. Next, the temperature was raised to 65 ° C., and the polymerization reaction was carried out by holding at 65 ° C. for 3 hours to obtain slurry C containing zinc oxide-containing resin particles C to be the core material part.
Next, the slurry C containing the zinc oxide-containing resin particles C is subjected to solid-liquid separation with a centrifuge, and then the separated solid is washed with pure water and further dried at 90 ° C. The contained resin particles C were collected.

B. Evaluation of Core Material Part The content rate of zinc oxide in the zinc oxide-containing resin particles C was measured according to Example 1. As a result, the zinc oxide content in the zinc oxide-containing resin particles C was 50% by mass.
Next, the zinc elution amount of the zinc oxide-containing resin particles C was measured according to Example 1. As a result, the zinc elution amount of the zinc oxide-containing resin particles C was 18 ppm.

C. Preparation of UV-shielding composite particles 30 parts by mass of MMA and 69.964 parts by mass of pure water were mixed with potassium persulfate dispersion in which 0.036 parts by mass of potassium persulfate was dissolved. Was made.
Next, 77.5 parts by mass of the slurry C containing the zinc oxide-containing resin particles C and 22.5 parts by mass of the emulsion C were mixed, and nitrogen substitution was performed at room temperature (25 ° C.) for 1 hour. Next, the temperature is raised to 65 ° C. and held at 65 ° C. for 3 hours to conduct a polymerization reaction, and a coating made of a methacrylic resin obtained by polymerizing MMA on the surface of the zinc oxide-containing resin particles C to be the core material part A film was formed.
Next, this reaction solution is subjected to solid-liquid separation with a centrifuge, and then the separated solid is washed with pure water and further dried at 90 ° C. to produce the ultraviolet shielding composite particles C of Example 3. did.

D. Evaluation of UV-shielding composite particles Next, the content of zinc oxide in the UV-shielding composite particles C was measured according to Example 1. As a result, the content of zinc oxide in the ultraviolet shielding composite particles C was 37% by mass.
Next, the zinc elution amount of the ultraviolet shielding composite particles C was measured according to Example 1. As a result, the zinc elution amount of the ultraviolet shielding composite particles C was 7 ppm.

[Example 4]
"Preparation of UV shielding composite particles"
A. Preparation of core material part According to Example 1, except that 55 parts by mass of zinc oxide particles (manufactured by Sumitomo Osaka Cement) having an average primary particle size of 0.02 μm were changed to 45 parts by mass. An MMA dispersion was prepared.
When the volume particle size distribution of the obtained dispersion was evaluated with a particle size distribution analyzer LB-550 (manufactured by Horiba, Ltd.), the particle size was 48 nm and the cumulative volume percentage was 50 volumes when the cumulative volume percentage was 10 vol% (d10). % (D50) had a particle size of 80 nm, and a cumulative volume percentage of 90 vol% (d90) had a particle size of 137 nm.

  Next, 30.00 parts by mass of the above zinc oxide / MMA dispersion, 64.75 parts by mass of pure water, 0.95 parts by mass of sodium dodecylbenzenesulfonate, 4 parts by mass of ethylene glycol dimethacrylate, silicone antifoaming agent KS -66 (manufactured by Shin-Etsu Chemical Co., Ltd.) 0.30 part by mass was mixed and stirred using a homogenizer to prepare an emulsion D.

Next, 80 parts by mass of the obtained emulsion D and a potassium persulfate solution obtained by dissolving 0.040 parts by mass of potassium persulfate in 19.960 parts by mass of pure water were mixed, and a reactor equipped with a stirrer and a thermometer was mixed. The nitrogen substitution was carried out at room temperature (25 ° C.) for 1 hour. Next, the temperature was raised to 65 ° C., and the polymerization reaction was carried out by holding at 65 ° C. for 3 hours to obtain a slurry D containing zinc oxide-containing resin particles D serving as a core part.
Next, the slurry D containing the zinc oxide-containing resin particles D is subjected to solid-liquid separation with a centrifuge, and then the separated solid is washed with pure water and further dried at 90 ° C. to obtain zinc oxide. The contained resin particles D were collected.

B. Evaluation of Core Material Part The content rate of zinc oxide in the zinc oxide-containing resin particles D was measured according to Example 1. As a result, the zinc oxide content in the zinc oxide-containing resin particles D was 45% by mass.
Next, the zinc elution amount of the zinc oxide-containing resin particles D was measured according to Example 1. As a result, the zinc elution amount of the zinc oxide-containing resin particles D was 14 ppm.

C. Preparation of UV shielding composite particles 30 parts by mass of MMA and 69.964 parts by mass of pure water were mixed with a potassium persulfate dispersion in which 0.036 parts by mass of potassium persulfate was dissolved, and the mixture was stirred and mixed with a homogenizer. Was made.
Next, 85 parts by mass of the slurry D containing the zinc oxide-containing resin particles D and 15 parts by mass of the emulsion D were mixed, and nitrogen substitution was performed at room temperature (25 ° C.) for 1 hour. Next, the temperature is raised to 65 ° C. and held at 65 ° C. for 3 hours to conduct a polymerization reaction, and a coating made of a methacrylic resin obtained by polymerizing MMA on the surface of the zinc oxide-containing resin particles D serving as a core part. A film was formed.
Next, the reaction solution is subjected to solid-liquid separation with a centrifuge, and then the separated solid is washed with pure water and further dried at 90 ° C. to produce the ultraviolet shielding composite particles D of Example 4. did.

D. Evaluation of UV shielding composite particles Next, the content of zinc oxide in the UV shielding composite particles D was measured according to Example 1. As a result, the content of zinc oxide in the ultraviolet shielding composite particle D was 36% by mass.
Next, the zinc elution amount of the ultraviolet shielding composite particles D was measured according to Example 1. As a result, the zinc elution amount of the ultraviolet shielding composite particles D was 3 ppm.

[Comparative Example 1]
"Preparation of zinc oxide-containing resin particles"
In accordance with Example 1, a zinc oxide / MMA dispersion of Comparative Example 1 was prepared.
When the volume particle size distribution of the obtained dispersion was evaluated with a particle size distribution analyzer LB-550 (manufactured by Horiba Seisakusho), the particle size at a cumulative volume percentage of 10% by volume (d10) was 54 nm, and the cumulative volume percentage was 50 volumes. % (D50) had a particle size of 87 nm, and a cumulative volume percentage of 90 vol% (d90) had a particle size of 160 nm.
Subsequently, the zinc oxide containing resin particle F of the comparative example 1 was produced according to Example 1 using said zinc oxide / MMA dispersion liquid.

"Evaluation of resin particles containing zinc oxide"
The content of zinc oxide in the zinc oxide-containing resin particles F was measured according to Example 1. As a result, the zinc oxide content in the zinc oxide-containing resin particles F was 53% by mass.
Next, the zinc elution amount of the zinc oxide-containing resin particles F was measured according to Example 1. As a result, the zinc elution amount of the zinc oxide-containing resin particles F was 18 ppm.

[Comparative Example 2]
"Preparation of zinc oxide-containing resin particles"
In accordance with Example 2, a zinc oxide / MMA dispersion of Comparative Example 2 was prepared.
When the volume particle size distribution of the obtained dispersion was evaluated with a particle size distribution analyzer LB-550 (manufactured by Horiba Seisakusho), the particle size was 53 nm and the cumulative volume percentage was 50 volumes when the cumulative volume percentage was 10 vol% (d10). % (D50) had a particle diameter of 82 nm, and the cumulative volume percentage was 90 volume% (d90), and the particle diameter was 128 nm.
Subsequently, the zinc oxide containing resin particle G of the comparative example 2 was produced according to Example 2 using said zinc oxide / MMA dispersion liquid.

"Evaluation of resin particles containing zinc oxide"
The content of zinc oxide in the zinc oxide-containing resin particles G was measured according to Example 1. As a result, the zinc oxide content in the zinc oxide-containing resin particles G was 51% by mass.
Next, the zinc elution amount of the zinc oxide-containing resin particles G was measured according to Example 1. As a result, the zinc elution amount of the zinc oxide-containing resin particles G was 19 ppm.

[Comparative Example 3]
"Preparation of zinc oxide-containing resin particles"
A zinc oxide / MMA dispersion of Comparative Example 3 was prepared according to Example 3.
When the volume particle size distribution of the obtained dispersion was evaluated with a particle size distribution analyzer LB-550 (manufactured by Horiba, Ltd.), the particle diameter was 49 nm and the cumulative volume percentage was 50 volumes when the cumulative volume percentage was 10 vol% (d10). % (D50) had a particle size of 80 nm, and a cumulative volume percentage of 90 vol% (d90) had a particle size of 134 nm.
Subsequently, the zinc oxide containing resin particle H of the comparative example 3 was produced according to Example 3 using said zinc oxide / MMA dispersion liquid.

"Evaluation of resin particles containing zinc oxide"
The content of zinc oxide in the zinc oxide-containing resin particles H was measured according to Example 1. As a result, the zinc oxide content in the zinc oxide-containing resin particles H was 50% by mass.
Next, the zinc elution amount of the zinc oxide-containing resin particles H was measured according to Example 1. As a result, the zinc elution amount of the zinc oxide-containing resin particles H was 18 ppm.

[Comparative Example 4]
"Preparation of zinc oxide-containing resin particles"
A zinc oxide / MMA dispersion of Comparative Example 4 was prepared according to Example 4.
When the volume particle size distribution of the obtained dispersion was evaluated with a particle size distribution analyzer LB-550 (manufactured by Horiba, Ltd.), the particle size was 48 nm and the cumulative volume percentage was 50 volumes when the cumulative volume percentage was 10 vol% (d10). % (D50) had a particle size of 80 nm, and a cumulative volume percentage of 90 vol% (d90) had a particle size of 137 nm.
Subsequently, the zinc oxide containing resin particle J of the comparative example 4 was produced according to Example 4 using said zinc oxide / MMA dispersion liquid.

"Evaluation of resin particles containing zinc oxide"
The content of zinc oxide in the zinc oxide-containing resin particles J was measured according to Example 1. As a result, the zinc oxide content in the zinc oxide-containing resin particles J was 45% by mass.
Next, the zinc elution amount of the zinc oxide-containing resin particles J was measured according to Example 1. As a result, the zinc elution amount of the zinc oxide-containing resin particles J was 14 ppm.
These evaluation results are shown in Table 1.

[Example 5]
"Preparation of UV shielding composite particles"
In accordance with Example 1, ultraviolet shielding composite particles E of Example 5 were produced.
Next, the zinc elution amount of the ultraviolet shielding composite particles E was measured according to Example 1. As a result, the zinc elution amount of the ultraviolet shielding composite particles E was 10 ppm.

[Preparation of dispersion containing ultraviolet shielding composite particles]
The above-mentioned ultraviolet shielding composite particle E35 parts by mass, polyether-modified silicone 8.1 parts by mass, decamethylcyclopentasiloxane SH245 (manufactured by Toray Dow Corning Co., Ltd.) 56.9 parts by mass are mixed together in a sand mill using glass beads. A dispersion E containing the ultraviolet shielding composite particles E was prepared.

When the dispersion volume particle size distribution of the obtained dispersion E was evaluated with a particle size distribution analyzer LB-550 (manufactured by Horiba, Ltd.), the dispersion particle size was 174 nm and the cumulative volume percentage was 10% by volume (d10). Was 50% by volume (d50), the dispersed particle diameter was 279 nm, and the dispersed particle diameter when the cumulative volume percentage was 90% by volume (d90) was 420 nm.
Moreover, when the zinc elution amount of this dispersion E was measured, it was below the detection limit (≦ 1 ppm), and zinc elution was not confirmed.

[Comparative Example 5]
10 parts by mass of zinc oxide particles having an average primary particle size of 0.02 μm (manufactured by Sumitomo Osaka Cement) and 90 parts by mass of pure water are mixed, and the zinc oxide particles are uniformly dispersed in pure water using an ultrasonic disperser. A 10% by weight aqueous suspension K of zinc oxide was prepared.
Next, an aqueous sodium silicate solution was added to the zinc oxide 10 mass% aqueous suspension K so as to be 10 mass% in terms of silicon oxide (SiO ₂ ) with respect to zinc oxide and mixed. A suspension K containing sodium acid was obtained.

  Next, 0.5 N dilute hydrochloric acid is gradually added to the zinc oxide silicate-containing suspension K to adjust the pH of the mixture to 7, and then the mixture is allowed to stand at room temperature (25 ° C.) for 6 hours. Suspension K was obtained.

Thereafter, the suspension K is filtered with a filter, and then the separated solid is washed with pure water and further dried at 105 ° C. to oxidize the surface of the zinc oxide particles with a silicon oxide film. Silicon-coated zinc oxide particles K were produced.
Next, the zinc elution amount of the silicon oxide-coated zinc oxide particles K was measured according to Example 1. As a result, the zinc elution amount of the silicon oxide-coated zinc oxide particles K was 34 ppm.

According to the above evaluation results, in Examples 1 to 4, the zinc elution amount was 10 ppm or less because the surface of the zinc oxide-containing resin particles serving as the core part was coated with the coating film made of methacrylic resin. On the other hand, in Comparative Examples 1-4, since it was the zinc oxide containing resin particle itself which consists only of the core part which is not coat | covered with a coating film, it turned out that zinc elution amount is as large as 14 ppm or more.
In Example 5, since the dispersion liquid E was produced using the ultraviolet shielding composite particles E, it was found that a dispersion liquid having a zinc elution amount of 10 ppm or less was obtained.
On the other hand, in Comparative Example 5, since the surface of the zinc oxide particles was only coated with the silicon oxide film, the zinc elution amount of the silicon oxide-coated zinc oxide particles K was as extremely large as 34 ppm.

  By the above, in Examples 1-5, since the surface of the core material part used as a core part was coat | covered with the coating film used as a shell part, the zinc oxide containing resin particle which consists only of the core part of Comparative Examples 1-4, It was found that the zinc elution amount was suppressed as compared with the silicon oxide-coated zinc oxide particles in which the surface of the zinc oxide particles of Comparative Example 5 was coated with a silicon oxide film.

  The ultraviolet shielding composite particles of the present invention include a core part containing zinc oxide and a first resin, and a second part having the same composition as or different from the first resin formed on the surface of the core part. And the coating film made of the resin, it is possible to prevent zinc ions from eluting from the zinc oxide contained in the composite particles. Since it can suppress the increase and decrease of the viscosity of cosmetics, UV shielding ability is required, and of course, it can be applied to cosmetics with excellent usability and dispersed when used in fields other than cosmetics. The range of choice of agents and resins is widened, and the degree of freedom in designing and blending paints and the like can be increased, and its industrial value is great.

DESCRIPTION OF SYMBOLS 1 Ultraviolet shielding composite particle 2 Core material part 2a Surface 3 Coating film

Claims (6)

  A core material portion containing zinc oxide and a first resin, and a coating film formed on the surface of the core material portion and made of a second resin having the same composition as or different from the first resin An ultraviolet shielding composite particle comprising:   2. The ultraviolet shielding composite particle according to claim 1, wherein a content of the zinc oxide is 15% by mass or more and 40% by mass or less with respect to a total mass including the core part and the coating film.   3. The ultraviolet shielding composite particle according to claim 1, wherein a mass of the coating film is 30% by mass or more and 70% by mass or less of a total mass including the coating film and the core part.   The ultraviolet shielding composite particle according to any one of claims 1 to 3, wherein the coating film contains an organic ultraviolet absorber.   An ultraviolet shielding composite particle-containing dispersion comprising the ultraviolet shielding composite particles according to any one of claims 1 to 4 dispersed in a dispersion medium.   It contains either one or both of the ultraviolet shielding composite particles according to any one of claims 1 to 4 and the ultraviolet shielding composite particle-containing dispersion according to claim 5 in a base material. Cosmetics to do.

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