JP2012240948A - Ultraviolet shielding agent, and ultraviolet shielding agent-containing dispersion containing the same, and cosmetic - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ultraviolet shielding agent which has high ultraviolet shielding effect, has excellent transparency, can be prescribed by mixing an inorganic ultraviolet shielding agent and an organic ultraviolet absorber, and can be blended into a water-in-oil type (O/W type) cosmetic as well as an oil-in-water type (W/O) type cosmetic, an ultraviolet shielding agent-containing dispersion containing the ultraviolet shielding agent, and a cosmetic.SOLUTION: The ultraviolet shielding agent contains: the first resin particles including an organic ultraviolet absorber and having the average particle diameter of 0.1 to 1 μm; and the second resin particles including metal oxide with ultraviolet shielding power and having the average particle diameter of 0.1 to 1 μm, and in which the organic ultraviolet absorber and the metal oxide are included in the range of (1:45) to (3:1).

Description

  The present invention relates to an ultraviolet shielding agent, an ultraviolet shielding agent-containing dispersion containing the ultraviolet shielding agent, and a cosmetic, and more specifically, various cosmetics such as skin care cosmetics, makeup cosmetics, and body care cosmetics, and in particular, needs ultraviolet shielding ability. The present invention relates to an ultraviolet shielding agent suitable for whitening skin care cosmetics, base makeup for makeup cosmetics, and sunscreen for body care cosmetics, a dispersion containing ultraviolet shielding agents containing the same, and cosmetics.

  Conventionally, as an ultraviolet shielding agent used in cosmetics, there are an inorganic ultraviolet shielding agent and an organic ultraviolet absorber, which are properly used depending on the application. Inorganic ultraviolet shielding agents and organic ultraviolet absorbers have different wavelengths of ultraviolet rays that can be shielded according to their types, and cosmetics are appropriately combined with these.

  Inorganic ultraviolet shielding agents scatter or reflect ultraviolet rays with a physical mechanism, and therefore have little effect on the skin, and are used in sunscreen agents in a wide range of layers from infants to adults.

  However, when zinc oxide or titanium oxide, which is an inorganic UV-screening agent, is included in the cosmetic, if the average dispersion particle size is 0.1 μm or more, the cosmetic will be whitened and transparent. There was a problem that it was not possible to make a natural finish. On the other hand, it is difficult to disperse zinc oxide or the like in the cosmetic with an average dispersed particle size of 0.1 μm or less. Even if the particles can be dispersed, such fine particles such as zinc oxide have a high surface activity, so that they feel rough when they come into contact with the skin.

  On the other hand, organic ultraviolet absorbers absorb energy chemically and convert it into thermal energy, preventing ultraviolet rays from penetrating into skin cells. In addition, it is used as a sunscreen for adults because it has a high ultraviolet shielding effect even in a small amount as compared with an inorganic ultraviolet shielding agent.

  However, since organic UV absorbers are insoluble in water, it is necessary to dissolve them in a specific solvent in order to exert their UV absorption effect, reducing the degree of freedom for prescription of cosmetics and sticking to cosmetics. There was a problem.

  And, when an inorganic ultraviolet shielding agent and an organic ultraviolet absorber are used in combination, the organic ultraviolet absorber is recrystallized due to the influence of metal ions, causing deterioration of the cosmetics, discoloration, and a decrease in feeling of use. There has been a problem that cosmetics cannot be formulated by freely mixing an inorganic ultraviolet shielding agent and an organic ultraviolet absorber.

  In order to solve the above-mentioned problem, a resin powder having an average particle size of 0.1 μm to 1 μm is formed by encapsulating an acrylic resin with metal oxide particles having an ultraviolet shielding property, and has a high transparency and a good usability. A powder has been proposed (Patent Document 1). Further, by using this resin powder, it is possible to prevent the organic ultraviolet absorbent and the metal oxide particles from coming into direct contact with each other, so that crystallization of the organic ultraviolet absorbent is suppressed.

  In addition, (meth) acrylic containing an organic ultraviolet absorber formed by dispersing a monomer forming a (meth) acrylic resin in which an organic ultraviolet absorber is dissolved in an aqueous medium and performing a polymerization reaction A cosmetic particle having a core part made of a resin and a surface layer part made of a (meth) acrylic resin not containing an organic UV absorber formed on the surface of the core part, and absorbing organic UV light A resin powder that suppresses the skin irritation of an agent has been proposed (Patent Document 2). By using this resin powder, the organic ultraviolet absorber is prevented from coming into direct contact with the metal oxide, so that crystallization of the organic ultraviolet absorber is suppressed.

International Publication No. 2011/034032 Japanese Patent Application Laid-Open No. 07-291837

  However, when an attempt is made to use the resin particles encapsulating the metal oxide having an ultraviolet shielding ability of Patent Document 1 and the organic ultraviolet absorber together, the organic ultraviolet absorber is insoluble in water, and therefore exhibits its ultraviolet shielding function. In order to achieve this, it was necessary to dissolve in a specific solvent. For this reason, it is difficult to mix and formulate water-based cosmetics, and there is a problem that the degree of freedom in formulating cosmetics is reduced. Moreover, even if it is a sunscreen agent which used together the resin particle which includes a metal oxide, and an organic type ultraviolet absorber, it cannot fully shield the UVA wave (wavelength 320-400 nm) which causes photoaging. There was a problem.

On the other hand, when the resin particles encapsulating the organic ultraviolet absorber of Patent Document 2 and the metal oxide particles having ultraviolet shielding ability are used in combination, the primary particle size of the metal oxide particles and the dispersed particle size in the cosmetic are When it is large, there is a problem that the transparency of the cosmetic is lowered. Further, the amount of organic UV absorbers that can be blended in cosmetics is generally limited, and there is a problem that the UV shielding effect of the organic UV absorber alone is not sufficient.
Therefore, even if it is a sunscreen agent which used together the resin particle which includes an organic type ultraviolet absorber, and the metal oxide particle which has ultraviolet-ray shielding ability, Among the UVA waves (wavelength 320-400 nm) which cause photoaging, In particular, there is a problem that ultraviolet rays having a wavelength of 380 nm to 400 nm cannot be sufficiently shielded.

  The present invention has been made in view of the above circumstances, and particularly has a high ultraviolet shielding effect at a wavelength of 380 nm to 400 nm, excellent transparency, and a mixture of an inorganic ultraviolet shielding agent and an organic ultraviolet absorber. It can be formulated, and it can be formulated into oil-in-water type (O / W type) cosmetics as well as water-in-oil type (W / O type) and contains it. It aims at providing the ultraviolet shielding agent containing dispersion liquid and cosmetics.

  As a result of intensive studies in order to solve the above problems, the present inventors have determined the average particle diameters of resin particles containing organic ultraviolet absorbers and resin particles containing metal oxides having ultraviolet shielding ability, respectively. By adjusting to a predetermined size and mixing these resin particles in a predetermined ratio range, the ultraviolet ray shielding ability at a wavelength of 380 nm to 400 nm is high, excellent in transparency, and easy to mix in water-based cosmetics. The inventors have found that an ultraviolet shielding agent can be obtained, and have completed the present invention.

That is, the ultraviolet shielding agent of the present invention contains the first resin particles containing an organic ultraviolet absorber and having an average particle size of 0.1 μm or more and 1 μm or less, and a metal oxide having an ultraviolet shielding ability and an average. An ultraviolet shielding agent comprising second resin particles having a particle size of 0.1 μm or more and 1 μm or less, wherein the organic ultraviolet absorber and the metal oxide are in a mass ratio of 1:45 to 3: 1. It is contained in the range of.
In addition, the ultraviolet shielding agent-containing dispersion of the present invention is characterized by containing the ultraviolet shielding agent.
The cosmetic of the present invention is characterized by containing at least one of the ultraviolet shielding agent and the ultraviolet shielding agent-containing dispersion.

  According to the ultraviolet shielding agent of the present invention, the first resin particles containing an organic ultraviolet absorber and the second resin particles containing a metal oxide having an ultraviolet shielding ability are adjusted to predetermined average particle sizes, respectively. As a result, the synergistic effect is obtained in the ultraviolet shielding ability of the organic ultraviolet absorber and the inorganic oxide, compared to the case where each resin particle is used alone, Ultraviolet rays having a wavelength of 380 nm to 400 nm can be further shielded.

  In addition, since it is not necessary to dissolve the organic ultraviolet absorber in a specific solvent, not only water-in-oil type (W / O type) but also oil-in-water type (O / W type) that has been difficult to formulate in the past. In addition, it can be formulated into water-based cosmetics such as lotions and sunscreen gels, and the degree of freedom in formulating cosmetics can be improved.

In addition, since the metal oxide particles used in the ultraviolet shielding agent of the present invention are fine particles having primary particles of 0.1 μm or less, high transparency can be obtained when blended and applied in cosmetics.
In addition, since the inorganic particles used in the ultraviolet shielding agent of the present invention are fine particles having primary particles of 0.1 μm or less, high transparency can be obtained when blended and applied to cosmetics.

It is a figure which shows the spectral transmission factor of each moisture gel of Example 1 of this invention and Comparative Examples 1 and 2. FIG.

The form for implementing the ultraviolet shielding agent of this invention, the ultraviolet-ray shielding agent containing dispersion containing it, 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.

[Ultraviolet shielding agent]
The ultraviolet shielding agent of the present embodiment contains the first resin particles containing an organic ultraviolet absorber and having an average particle diameter of 0.1 μm or more and 1 μm or less, and a metal oxide having an ultraviolet shielding ability and containing an average particle. An ultraviolet shielding agent comprising second resin particles having a diameter of 0.1 μm or more and 1 μm or less, wherein the organic ultraviolet absorber and the metal oxide have a mass ratio of 1:45 to 3: 1. It is characterized by a range.

  First resin particles containing an organic ultraviolet absorber (hereinafter sometimes abbreviated as ultraviolet absorber-containing resin particles) and second resin particles containing a metal oxide having an ultraviolet shielding ability (hereinafter referred to as metal) Oxide-containing resin particles may be abbreviated as a mixture of organic UV absorber and metal oxide in a mass ratio of 1: 45-3: 1, preferably 1: 6-3: 1. Has been. By mixing within this range, a synergistic effect of the ultraviolet shielding effect of the ultraviolet absorbent-containing resin particles and the metal oxide-containing resin particles can be obtained, and ultraviolet rays having a wavelength of 380 nm to 400 nm can be obtained as compared with the case where these resin particles are used alone. The shielding effect is increased.

"Ultraviolet absorber-containing resin particles (first resin particles)"
The average particle size of the ultraviolet absorbent-containing resin particles of the present embodiment is 0.1 μm or more and 1 μm or less, preferably 0.1 μm or more and 0.6 μm or less, more preferably 0.1 μm or more and 0.4 μm or less. . Here, by setting the average particle diameter of the resin particles in the above range, a synergistic effect of the ultraviolet shielding effect of the ultraviolet absorbent-containing resin particles and the metal oxide-containing resin particles can be obtained, and when these resin particles are used alone As a result, the ultraviolet shielding effect with a wavelength of 380 nm to 400 nm is enhanced.

Here, the average particle diameter of the ultraviolet absorbent-containing resin particles is 5 mass% of the ultraviolet absorbent-containing resin particles, 10 mass% of polyether-modified silicone (SH3775M manufactured by Toray Dow Corning Co., Ltd.), decamethylcyclo A dispersion obtained by dispersing pentasiloxane (manufactured by Toray Dow Corning Co., Ltd., SH245) with a sand mill at 2500 rpm for 3 hours is used with a dynamic light scattering particle size distribution analyzer (manufactured by Horiba, LB-550). The cumulative volume particle size distribution when the dispersed particle size is measured means a particle size of 50 volume% (D50).
In addition, the dispersed particle diameter of D50 obtained by the above measurement method substantially coincides with the primary particle diameter of the resin particles when the ultraviolet absorbent-containing resin particles are observed with a scanning electron microscope. Therefore, you may measure the average primary particle diameter of a ultraviolet absorber containing resin particle as an average particle diameter of a ultraviolet absorber containing resin particle.

  The content of the organic ultraviolet absorbent in the ultraviolet absorbent-containing resin particles is preferably 0.1% by mass or more and 80% by mass or less, more preferably 0.5% by mass or more and 50% by mass or less, and still more preferably. It is 1 mass% or more and 30 mass% or less.

  Here, when the content of the organic ultraviolet absorber in the resin is less than 0.1% by mass, the amount of the organic ultraviolet absorber is too small and the ultraviolet shielding function of the organic ultraviolet absorber is sufficiently developed. I can't do that. As a result, a large amount of resin particles is required to sufficiently develop the ultraviolet shielding function, and it is not preferable because the material design for producing a cosmetic becomes extremely difficult. On the other hand, when the content exceeds 80% by mass, the amount of the organic ultraviolet absorber becomes too high relative to the resin, and as a result, the dispersibility of the organic ultraviolet absorber in the resin is lowered, and the ultraviolet rays are reduced. Since the uniformity of the composition of the absorbent-containing resin particles is impaired, it is not preferable.

<Resin>
The resin used for the ultraviolet absorbent-containing resin particles is a resin that can dissolve the organic ultraviolet absorbent and has high transparency of the monomer polymer and can be used as a raw material for cosmetics. If there is no particular limitation.
Examples of such resin monomers include (meth) acrylic resins, acrylic esters, methacrylic esters, acrylic styrene copolymers, acrylamide copolymers, acrylic epoxy copolymers, acrylic urethane copolymers, acrylic polyester copolymers. A monomer such as a polymer, a silicon acrylic copolymer, a vinyl acetate resin, a polyamide resin, an epoxy resin, a urethane resin, a polyester resin, or a silicone resin can be used. Among these, a monomer of (meth) acrylic resin is preferable in that it is excellent in transparency.

  As a monomer of (meth) acrylic resin, methyl acrylate, ethyl acrylate, propyl acrylate, n-butyl acrylate, isobutyl acrylate, hexyl acrylate, 2-ethylhexyl acrylate, n-octyl acrylate, acrylic acid Dodecyl, lauryl acrylate, stearyl acrylate, 2-chloroethyl acrylate, phenyl acrylate, methyl α-chloroacrylate, trifluoroethyl acrylate, tetrafluoropropyl acrylate, methyl methacrylate, ethyl methacrylate, propyl methacrylate N-butyl methacrylate, isobutyl methacrylate, hexyl methacrylate, 2-ethylhexyl methacrylate, n-octyl methacrylate, dodecyl methacrylate, lauryl methacrylate, Lil and the like.

  Examples of monomers that can be polymerized in combination with the acrylic include styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, α-methylstyrene, o-ethylstyrene, m-ethylstyrene, p- Ethyl styrene, 2,4-dimethyl styrene, pn-butyl styrene, pt-butyl styrene, pn-hexyl styrene, pn-octyl styrene, 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 butyrate, N-vinyl pyrovinyl , Vinylidene fluoride, tetrafluoroethylene, hexafluoropropylene, pig Ene, isoprene.

  These resin monomers may be used by polymerizing only one kind alone or in combination of two or more kinds. For example, when combining a monomer of a (meth) acrylic resin and another monomer, the content of the monomer of the (meth) acrylic resin in the resin monomer is preferably 10% by mass or more from the viewpoint of transparency. More preferably, it is 30% by mass or more.

<Organic UV absorber>
The organic ultraviolet absorber is not particularly limited as long as it can be dissolved in the above resin monomer. For example, dibenzoylmethane compound, benzophenone derivative, paraaminobenzoic acid derivative, methoxycinnamic acid derivative, salicylic acid derivative Etc. These organic ultraviolet absorbers may be used alone or in combination of two or more.

The ultraviolet absorbent-containing resin particles may be surface-treated with organosiloxane. By treating the surface of the UV-absorber-containing resin particles with organosiloxane, a water-repellent effect can be obtained, making it less likely to be washed away by sweat, improving familiarity with the oil, and increasing the affinity with the skin. can do.
The amount of organosiloxane is preferably 1% by mass or more and 20% by mass or less with respect to the ultraviolet shielding agent-containing resin particles.

  Examples of the organosiloxane used for the surface treatment include dialkylalkoxysilane compounds. Among them, organopolysiloxane or modified organopolysiloxane modified with one or more selected from the group of alkyl group, isocyanate group, epoxy group, acrylic group and alkyl silicon compound is preferably used. It is done. In particular, dimethylpolysiloxane (silicone oil) and modified dimethylpolysiloxane (modified silicone oil) obtained by modifying dimethylpolysiloxane (silicone oil) are preferably used.

"Metal oxide-containing resin particles (second resin particles)"
The average particle diameter of the metal oxide-containing resin particles of the present embodiment is 0.1 μm or more and 1 μm or less, preferably 0.1 μm or more and 0.6 μm or less, more preferably 0.1 μm or more and 0.4 μm or less. . Here, by setting the average particle diameter of the metal oxide-containing resin particles in the above range, a synergistic effect of the ultraviolet shielding effect of the ultraviolet absorber-containing resin particles and the metal oxide-containing resin particles can be obtained. The ultraviolet shielding effect of 380 nm to 400 nm is enhanced as compared with the case of using particles.

Here, the average particle size of the metal oxide particle-containing resin particles is 5% by mass of the metal oxide-containing resin particles, polyether-modified silicone (Toray Dow Corning SH3775M), like the ultraviolet absorber-containing resin particles. A dynamic light scattering particle size distribution measuring apparatus (manufactured by Horiba, Ltd., LB) obtained by dispersing 10% by mass of decamethylcyclopentasiloxane (manufactured by Toray Dow Corning Co., Ltd., SH245) with a sand mill at 2500 rpm for 3 hours. -550) is used to measure the dispersed particle size, and the cumulative volume particle size distribution means a particle size of 50% by volume (D50).
In addition, the dispersed particle diameter of D50 obtained by the above measurement method substantially coincides with the primary particle diameter of the resin particles when the metal oxide-containing resin particles are observed with a scanning electron microscope. Therefore, you may measure the average primary particle diameter of a metal oxide containing resin particle as an average particle diameter of a metal oxide containing resin particle.

<Metal oxide particles>
The metal oxide having an ultraviolet shielding ability is a particle having an ultraviolet shielding ability containing one or more selected from the group consisting of zinc oxide, titanium oxide, cerium oxide, and iron oxide. The average primary particle diameter of the metal oxide is 0.003 μm or more and 0.1 μm or less, more preferably 0.01 μm or more and 0.05 μm or less, and further preferably 0.02 μm or more and 0.04 μm or less.

  When the average primary particle diameter of the metal oxide is less than 0.003 μm, the degree of crystallinity is lowered and the ultraviolet shielding function is not exhibited, and when the average primary particle diameter exceeds 0.1 μm, the particles are scattered with respect to visible light. Since the coefficient becomes large, the transparency is remarkably lowered, and as a result, the light transmittance with respect to visible light is lowered and the transparency is deteriorated.

  As the metal oxide, one obtained by surface-treating particles with one or more selected from the group consisting of silica, alumina, and organopolysiloxane may be used. When the metal oxide is surface-treated with one or more selected from the group consisting of silica, alumina and organopolysiloxane, the dispersion stability when dispersed in the monomer is improved.

  The content of the metal oxide in the resin particles is preferably 1% by mass or more and 80% by mass or less, more preferably 5% by mass or more and 70% by mass or less, and further preferably 10% by mass or more and 60% by mass or less. is there.

  Here, when the content of the metal oxide in the resin particles is less than 1% by mass, the amount of the metal oxide is too small to fully exhibit the ultraviolet shielding function of the metal oxide. Therefore, in order to sufficiently exhibit the ultraviolet shielding function, a large amount of metal oxide-containing resin particles are required, and it becomes extremely difficult to design a material when producing a cosmetic. On the other hand, when the content exceeds 80% by mass, the amount of the metal oxide is relatively high with respect to the resin, and as a result, the dispersibility of the metal oxide in the resin is reduced, and the metal oxide-containing resin particles Since the uniformity of the composition is impaired, it is not preferable.

  The resin is not particularly limited as long as the monomer polymer has high transparency and can be used as a raw material for cosmetics. And since the completely same monomer as the resin material demonstrated by the item of <resin> mentioned above can be used, description is abbreviate | omitted.

The metal oxide-containing resin particles may be surface-treated with organosiloxane. The amount of the organosiloxane is preferably 1% by mass to 20% by mass with respect to the metal oxide resin particles.
Examples of the organosiloxane include dialkylalkoxysilane compounds. Among them, organopolysiloxane or modified organopolysiloxane modified with one or more selected from the group of alkyl group, isocyanate group, epoxy group, acrylic group and alkyl silicon compound is preferably used. It is done. In particular, dimethylpolysiloxane (silicone oil) and modified dimethylpolysiloxane (modified silicone oil) obtained by modifying dimethylpolysiloxane (silicone oil) are preferably used.

By treating the surface of the metal oxide-containing resin particles with organosiloxane, the following advantages can be obtained.
First, when zinc oxide is used as the metal oxide, zinc oxide has the property of being dissolved in water in a small amount. However, by treating the surface of the metal oxide-containing resin particles with organosiloxane, Elution of zinc oxide from the resin particles can be effectively suppressed. Moreover, when using titanium oxide as said metal oxide, the effect which suppresses the surface activity of titanium oxide is acquired by surface-treating with organosiloxane.

The organic ultraviolet absorber and the metal oxide may be used in appropriate combination in consideration of the wavelength region that each material can absorb or shield.
For example, zinc oxide is an n-type metal oxide semiconductor, and the band gap energy in its band structure is 3.2 eV. Therefore, when the zinc oxide is irradiated with light having energy higher than the band gap energy, the electrons absorb the light energy and are excited from the valence band to the conduction band. Since the absorption edge of zinc oxide is in the vicinity of a wavelength of 380 nm, zinc oxide can absorb the wavelength region from long wavelength ultraviolet rays (UVA) to medium wavelength ultraviolet rays (UVB). From the above, it is preferable to use in combination with an organic ultraviolet absorber capable of shielding long wavelength ultraviolet rays (UVA) and an organic ultraviolet absorber capable of shielding medium wavelength ultraviolet rays (UVB).

  Titanium oxide has a band gap energy of 3.0 eV to 3.2 eV in its band structure, but since the excitation of electrons in titanium oxide is an indirect transition, the absorption wavelength assumed from the value of the energy gap. Absorption of light starts from the vicinity of the wavelength of 320 nm, which is on the far lower wavelength side. Therefore, titanium oxide has a strong effect of shielding the wavelength region of medium wavelength ultraviolet rays (UVB), and is preferably used in combination with an organic ultraviolet absorber capable of shielding long wavelength ultraviolet rays (UVA).

  Examples of combinations of organic ultraviolet absorbers and metal oxide particles include a combination of zinc oxide capable of shielding a wavelength region of 380 nm or less and avobenzone having a maximum absorption at a wavelength of 358 nm to 360 nm. Can do.

  In the present embodiment, ultraviolet absorber-containing resin particles (first resin particles) containing an organic ultraviolet absorber having an average particle size of 0.1 μm or more and 1 μm or less, and an average particle size of 0.1 μm or more and Metal oxide-containing resin particles (second resin particles) containing metal oxide particles having an ultraviolet shielding ability of 1 μm or less, and an organic ultraviolet absorber and metal oxide contained therein have a predetermined mass When mixed so as to have a ratio (1:45 to 3: 1), the effect of shielding ultraviolet rays having a wavelength of 380 nm to 400 nm is enhanced as compared with the case of using them alone. The details of the mechanism for obtaining such an effect are unknown, but are considered as follows.

  First, in the case of an ultraviolet shielding agent containing only ultraviolet absorber-containing resin particles, ultraviolet rays are absorbed by the organic ultraviolet absorber in the ultraviolet absorber-containing resin particles, but the light passes through the resin particles almost linearly. Therefore, it is thought that the ultraviolet ray absorption efficiency in each resin particle is low, and therefore, ultraviolet rays having a wavelength of 380 nm to 400 nm cannot be sufficiently shielded.

  On the other hand, in the case of an ultraviolet shielding agent containing only metal oxide-containing resin particles, the ultraviolet rays are shielded while being reflected and scattered by the metal oxide. Therefore, when compared with an ultraviolet shielding agent containing only ultraviolet absorbent-containing resin particles, the time for ultraviolet rays to pass through the resin particles is relatively long, and the time for contact between the metal oxide and ultraviolet rays is also relatively long. . However, since the metal oxide itself has a low ability to shield ultraviolet rays in the range of 380 nm to 400 nm, it cannot be shielded sufficiently.

  On the other hand, in the case of an ultraviolet shielding agent containing both ultraviolet absorber-containing resin particles and metal oxide-containing resin particles, incident light is reflected and scattered by the metal oxide-containing resin particles, Absorbed by the absorbent-containing resin particles. The light reflected by the metal oxide-containing resin particles reaches the ultraviolet absorber-containing resin particles and is absorbed. By repeating this, the ultraviolet shielding agent of the present embodiment is shielded by a metal oxide and absorbed by an organic ultraviolet absorber many times. That is, it is considered that the number of times that the ultraviolet rays pass through the resin particles due to the scattering and reflection of the metal oxide is larger than that when the ultraviolet absorbent-containing resin particles are used alone, and more ultraviolet rays can be shielded. These effects are considered to provide a synergistic effect of ultraviolet shielding by the organic ultraviolet absorber and the metal oxide.

  And since the space | gap which arises between resin particles becomes small by making the average particle diameter of each resin particle into 1 micrometer or less, the distance of the metal oxide and organic type ultraviolet absorber in a resin particle also becomes relatively short. . Therefore, it is considered that the absorption of ultraviolet rays by the organic ultraviolet absorber and the shielding of the ultraviolet rays by the metal oxide are more easily performed, and the synergistic effect of the ultraviolet shielding is more easily obtained.

Furthermore, by setting the mass ratio of the organic ultraviolet absorber to the metal oxide to 1:45 to 3: 1, the absorption effect by the organic ultraviolet ray can be balanced with the shielding effect, scattering and reflection effect by the metal oxide. Therefore, it is considered that a synergistic effect of ultraviolet shielding is easily obtained.
Due to the above effects, it is estimated that the ultraviolet shielding agent of the present embodiment can enhance the ultraviolet shielding effect with a wavelength of 380 nm to 400 nm, rather than using each resin particle alone.

  The ultraviolet shielding agent of this embodiment may contain the organic ultraviolet absorber or the inorganic particles separately depending on the application. For example, in the case of oil-based cosmetics such as a water-in-oil type (W / O type), an organic ultraviolet absorber is contained by separately adding an organic ultraviolet absorber to the ultraviolet shielding agent of this embodiment. The amount of resin particles added can be reduced, and a cosmetic with higher transparency can be obtained.

[Production method of UV screening agent]
The ultraviolet shielding agent of this embodiment is obtained by a step of producing metal oxide-containing resin particles, a step of producing ultraviolet absorber-containing resin particles, and a step of mixing ultraviolet absorber-containing resin particles and metal oxide-containing resin particles. It is done.

"Production process of metal oxide-containing resin particles"
In the method for producing metal oxide-containing resin particles of the present embodiment, first, a resin monomer containing a metal oxide having an ultraviolet shielding ability and a dispersant of 1% by mass to 50% by mass with respect to the metal oxide. Disperse in to form a resin monomer dispersion.
Next, the resin monomer dispersion is added to the resin monomer dispersion in an amount of 0.1% by mass to 10% by mass of a suspension protectant and 0.01% by mass to 5% by mass of a silicone-based polymer. A suspension or emulsion having a dispersed particle size of 0.1 μm or more and 1.2 μm or less, suspended or emulsified in pure water containing a foaming agent and 0.1% by weight or more and 10% by weight or less of a crosslinking agent; To do.
Next, by adding 0.01% by mass or more and 1% by mass or less of a polymerization initiator to the suspension or emulsion, suspension polymerization or emulsion polymerization is performed. And producing metal oxide-containing resin particles.

  Hereinafter, each process in the manufacturing method of a metal oxide containing resin particle is demonstrated in detail.

First, metal oxide particles having ultraviolet shielding ability are dispersed in a resin monomer containing a dispersant to obtain a resin monomer dispersion.
Since the metal oxide having ultraviolet shielding ability is exactly the same as the metal oxide described in the above item <Metal oxide>, the description is omitted.

<Dispersant>
As the dispersant, those having high affinity with the resin monomer and high hydrophobicity are preferable. That is, the dispersing agent promotes the dispersion to the resin monomer by coating the metal oxide, and at the same time, the metal oxide particles are almost monodispersed in a relatively short time, and the average dispersion in the monomer dispersion liquid The particle size (volume distribution D50) is 0.003 μm or more and 0.1 μm or less.
In addition, since the dispersant imparts hydrophobicity to the metal oxide, it helps the metal oxide to be taken into the resin without moving out of the polymer and moving to the aqueous phase.

  Examples of such a dispersant include carboxylic acids such as sodium carboxymethyl cellulose or salts thereof, sulfonic acids such as sodium alkanesulfonate or salts thereof, sulfate esters such as polyoxyethylene nonylphenyl ether sodium sulfate or salts thereof, Examples thereof include phosphoric acid esters such as oxyethylene alkylphenyl ether phosphoric acid and polyoxyethylene alkyl ether phosphoric acid or salts thereof, and phosphonic acids such as sodium lauryl phosphate or salts thereof.

In particular, when the ultraviolet shielding agent of the present embodiment is used in cosmetics, these dispersants must be recognized as raw materials for cosmetics at the same time.
The addition ratio of the dispersant to the metal oxide is preferably 1% by mass or more and 50% by mass or less. If the addition rate is less than 1% by mass, it is too small to cover the surface of the metal oxide, so that a sufficient dispersion state of the metal oxide cannot be obtained. Even if it raises, dispersibility cannot be improved further and a dispersing agent becomes useless.

  The metal oxide is preferably contained in the monomer dispersion by 1 to 80% by mass, preferably 5 to 70% by mass, more preferably 10 to 60% by mass. Here, when the content of the metal oxide in the monomer dispersion is less than 1% by mass, the amount of the metal oxide in the resin obtained by polymerizing the monomer is too small, and the ultraviolet shielding function of the metal oxide is sufficiently obtained. It becomes impossible to express. For this reason, in order to sufficiently develop the ultraviolet shielding function, a large amount of resin is required, which makes it extremely difficult to design a material for producing a cosmetic product. On the other hand, when the content exceeds 80% by mass, the amount of the metal oxide is relatively high with respect to the monomer, and as a result, the dispersibility of the metal oxide in the monomer dispersion and the resin obtained by polymerizing the monomer is lowered. In addition, the uniformity of the composition of the metal oxide-containing resin particles is impaired, which is not preferable.

The dispersing device used is not particularly limited as long as it can impart sufficient dispersion energy to the dispersion system, and examples thereof include a ball mill, a sand mill, an ultrasonic disperser, and a homogenizer.
The dispersion time is preferably about 30 minutes to 3 hours, but an appropriate time may be selected in consideration of the dispersion state and the manufacturing cost.

The average dispersed particle size (volume distribution D50) of the metal oxide particles in the monomer dispersion is preferably 0.3 μm or less, more preferably 0.2 μm or less, and still more preferably 0.1 μm or less.
Here, when the average dispersion particle size in the monomer dispersion of the metal oxide exceeds 0.1 μm, when the monomer is polymerized into a resin, the scattering coefficient of the metal oxide in the resin with respect to visible light is large and transparent. As a result, the transparency is lowered and, as a result, there is a possibility of devitrification.

  Next, the obtained resin monomer dispersion is suspended or emulsified in pure water containing a suspension protective agent, a silicone-based antifoaming agent, and a crosslinking agent, and the dispersed particle size (volume distribution D50) is 0.1 μm or more. The suspension or emulsion is 1.2 μm or less.

  In order to obtain metal oxide-containing resin particles having an average particle diameter of 0.1 μm or more and 1 μm or less, it is preferable to suspend or emulsify at about 6000 rpm to 10000 rpm for about 10 minutes to 20 minutes.

<Suspension protectant>
Suspension protectants include nonionic surfactants such as polyoxyethylene alkyl ethers and polyoxyethylene alkylphenyl ethers, or anionic interfaces such as alkylbenzene sulfonates, alkyl sulfates, and alkylphenyl sulfates. An anionic surfactant is preferable among these, and an alkylbenzene sulfonate is preferable as this anionic surfactant.
The addition amount of the suspension protective agent is 0.1% by mass or more and 10% by mass or less, and more preferably 0.1% by mass or more and 2% by mass or less with respect to the resin monomer dispersion.

<Silicone-based antifoaming agent>
Examples of the silicone antifoaming agent include an oil type, an oil compound type, a solution type, a powder type, a solid type, an emulsion type, and a self-emulsifying type. Among these, an oil compound type is preferable.
The addition amount of the silicone-based antifoaming agent is preferably 0.01% by mass or more and 5% by mass or less, and more preferably 0.1% by mass or more and 1% by mass or less with respect to the resin monomer dispersion. is there.

  Silicone antifoaming agent is added in an amount of 0.01% by mass to 5% by mass with respect to the resin monomer dispersion, thereby greatly increasing the stirring speed of a mixer, agitator, homomixer, homogenizer, etc. The resin particles can be reduced to about 0.1 μm. As a result, the stirring speed of a mixer, stirrer, homomixer, homogenizer, etc. can be significantly increased, and as a result, the production efficiency of resin particles can be improved, so that the production cost can be greatly reduced. it can.

<Crosslinking agent>
The crosslinking agent is not particularly limited as long as it is a monomer having two or more unsaturated double bonds, but is not limited to a polyfunctional vinyl monomer or a polyfunctional (meth) acrylic acid ester derivative. Etc. can be appropriately selected and used.
More specifically, divinylbenzene, divinylbiphenyl, divinylnaphthalene, (poly) ethylene glycol di (meth) acrylate, (poly) propylene glycol di (meth) acrylate, (poly) tetramethylene glycol di (meth) acrylate, etc. (Poly) alkylene glycol type | system | group di (meth) acrylate is mentioned.

  1,6-hexanediol di (meth) acrylate, 1,8-octanediol di (meth) acrylate, 1,9-nonanediol di (meth) acrylate, 1,10-decanediol di (meth) acrylate, 1,12-dodecanediol di (meth) acrylate, 3-methyl-1,5-pentanediol di (meth) acrylate, 2,4-diethyl-1,5-pentanediol di (meth) acrylate, butylethylpropanediol Examples include alkanediol di (meth) acrylates such as di (meth) acrylate, 3-methyl-1,7-octanediol di (meth) acrylate, and 2-methyl-1,8-octanediol di (meth) acrylate. .

Also, neopentyl glycol di (meth) acrylate, trimethylolpropane tri (meth) acrylate, tetramethylolmethane tri (meth) acrylate, tetramethylolpropane tetra (meth) acrylate, pentaerythritol tri (meth) acrylate, ethoxylated cyclohexanedi Methanol di (meth) acrylate, ethoxylated bisphenol A di (meth) acrylate, tricyclodecane dimethanol di (meth) acrylate, propoxylated ethoxylated bisphenol A di (meth) acrylate, 1,1,1-trishydroxymethylethane Di (meth) acrylate, 1,1,1-trishydroxymethylethane tri (meth) acrylate, 1,1,1-trishydroxymethylpropane triacrylate, diary Phthalate and its isomers, triallyl isocyanurate and derivatives thereof.
Among these, (poly) ethylene glycol di (meth) acrylate is particularly preferable.
The addition amount of the crosslinking agent is preferably 0.1% by mass or more and 10% by mass or less, more preferably 1% by mass or more and 10% by mass or less with respect to the resin monomer dispersion.

<Pure water>
The pure water is not particularly limited as long as it is water generally used in cosmetics, and includes ion exchange water, distilled water, purified water, ultrapure water, natural water, alkaline ionized water, deep water and the like. Pure water may be added so as to be 40 mass% or more and 80 mass% or less, preferably 50 mass% or more and 70 mass% or less with respect to the total amount of the suspension or emulsion.

  Subsequently, a polymerization initiator is added to said suspension or emulsion, and suspension polymerization or emulsion polymerization is performed.

<Polymerization initiator>
Polymerization initiators include persulfates such as potassium persulfate and ammonium persulfate, hydrogen peroxide, benzoyl peroxide, lauroyl peroxide, t-butyl hydroperoxide, benzoyl peroxide, cumene hydroperoxide, and other organic peroxides. And azo initiators such as azobisdiisobutyronitrile and 2,2-azobis (2-amidinopropane) dihydrochloride, among which persulfate is preferable.

  The addition amount of the polymerization initiator is preferably 0.01% by mass or more and 1% by mass or less, and more preferably 0.05% by mass or more and 0.5% by mass or less with respect to the resin monomer dispersion.

As the polymerization method, a method is preferred in which the above suspension or emulsion is heated while stirring in a nitrogen atmosphere and in the presence of a polymerization initiator to initiate polymerization.
The polymerization initiation temperature is preferably 50 to 80 ° C. The polymerization time while maintaining this temperature is preferably about 1 to 5 hours, and an appropriate time may be selected in consideration of the time when the unreacted residual monomer is minimized, the polymerization state, and the production cost.
Then, a polymer can be obtained by cooling with ice or natural cooling to stop the polymerization reaction.

  By limiting the contents of these suspension protective agent, silicone-based antifoaming agent and polymerization initiator to the above ranges, and carrying out the suspension under suitable suspension or emulsification conditions, the average particle size of the resin particles obtained is 0.00. It can be controlled to 1 μm or more and 1 μm or less.

  Subsequently, in order to remove the remaining monomer, polymerization initiator and surfactant from the obtained polymer, the product was sufficiently washed with alcohol, then washed with pure water, and dried. The metal oxide-containing resin particles are crushed.

The alcohol is not particularly limited as long as it is soluble in pure water and can be easily washed away. Examples thereof include ethanol and 2-propanol, and 2-propanol is particularly preferable.
The washing method is not particularly limited as long as residual monomers can be removed, but washing is performed by pressure filtration, suction filtration, filter press, centrifugation, ultrafiltration, decantation, or the like.

  After completion of washing, the obtained polymer is dried at 80 ° C. to 100 ° C. to remove alcohol and pure water, and then the obtained polymer is crushed. The drying method is not particularly limited as long as it is a method capable of removing alcohol and pure water, and examples thereof include drying in atmospheric pressure and vacuum drying.

The crushing method is not particularly limited as long as each particle can be crushed, and examples thereof include a pin mill, a hammer mill, a jet mill, and an impeller mill.
As described above, the metal oxide-containing resin particles can be generated.

"Manufacturing process of UV absorber-containing resin particles"
In the method for producing the ultraviolet absorbent-containing resin particles of the present embodiment, first, an organic ultraviolet absorbent is used as the resin monomer, and the content of the organic ultraviolet absorbent is 0.1% by mass or more and 80% by mass or less. In this way, a resin monomer solution is obtained.
Next, the resin monomer solution is added to the resin monomer solution in an amount of 0.1% by mass to 10% by mass of a suspension protective agent, 0.01% by mass to 5% by mass of a silicone-based antifoaming agent. And suspended or emulsified in pure water containing an agent and 0.1% by mass or more and 10% by mass or less of a crosslinking agent to obtain a suspension or emulsion.
Subsequently, 0.01% by mass or more and 1% by mass or less of a polymerization initiator is added to the suspension or emulsion to perform suspension polymerization or emulsion polymerization. System ultraviolet absorbing resin particles are produced.

  Hereinafter, each manufacturing process of the ultraviolet absorbent-containing resin particles will be described in detail.

<Production process of resin monomer solution>
An organic ultraviolet absorber is dissolved in the resin monomer so as to be 0.1% by mass to 80% by mass to obtain a resin monomer solution.
Since the organic ultraviolet absorber is exactly the same as the organic ultraviolet absorber described in the above item <Organic ultraviolet absorber>, the description thereof is omitted.

In order to increase the polymerization efficiency with respect to the resin monomer solution, 1% by mass or more and 50% by mass or less of a dispersant may be mixed. If the addition ratio of the dispersant is less than 1% by mass, the emulsion film strength of the suspension or emulsion described later does not increase, and as a result, the polymerization efficiency of suspension polymerization or emulsion polymerization may decrease. . On the other hand, if it exceeds 50% by mass, the polymerization efficiency cannot be further improved even if the addition rate is further increased, and the dispersant is wasted.
Usable dispersants are exactly the same as the dispersants described in the above <Dispersant> section, and the description thereof is omitted.

The organic ultraviolet absorber is 0.1% by mass or more and 80% by mass or less, preferably 0.5% by mass or more and 50% by mass or less, more preferably 1% by mass or more and 30% by mass in the resin monomer solution. The following is included.
Here, when the content of the organic ultraviolet absorber in the monomer solution is less than 0.1% by mass, the amount of the organic ultraviolet absorber is too small, and the resin obtained by polymerizing the monomer is the organic ultraviolet absorber. The ultraviolet shielding function that it has cannot be fully expressed. As a result, it is not preferable to sufficiently develop the ultraviolet shielding function because a large amount of resin is required, and material design for producing cosmetics becomes extremely difficult. On the other hand, when the content exceeds 80% by mass, the amount of the organic ultraviolet absorber becomes relatively high with respect to the monomer solution, and as a result, the dispersibility of the organic ultraviolet absorber in the monomer solution decreases. In addition, the uniformity of the composition of the ultraviolet absorber-containing resin particles is impaired, which is not preferable.

  Next, the resin monomer solution is suspended or emulsified in pure water containing a suspension protective agent, a silicone-based antifoaming agent and a crosslinking agent, and the dispersed particle size (volume distribution D50) is 0.1 μm or more and 1.2 μm. The following suspension or emulsion is used. Since this step is exactly the same as the suspension or emulsion preparation step in the above-described production process of the metal oxide-containing resin particles, description thereof is omitted.

  Subsequently, a polymerization initiator is added to said suspension or emulsion, and suspension polymerization or emulsion polymerization is performed. Since this suspension polymerization or emulsion polymerization step is exactly the same as the suspension polymerization or emulsion polymerization step in the above-described production process of metal oxide-containing resin particles, description thereof is omitted.

Subsequently, in order to remove the remaining monomer, polymerization initiator and surfactant from the obtained polymer, the product was sufficiently washed with alcohol, then washed with pure water, and dried. The resin particles are crushed. Since this step is exactly the same as the washing, drying, and crushing steps in the above-described production process of the metal oxide-containing resin particles, description thereof is omitted.
As described above, the ultraviolet absorbent-containing resin particles can be generated.

The ultraviolet absorber-containing resin particles and the metal oxide-containing resin particles obtained above are mixed so that the organic ultraviolet absorber and the metal oxide are in a range of 1:45 to 3: 1 by mass ratio.
The mixing method is not particularly limited, and dry powder resin particles may be mixed, or the ultraviolet absorbent-containing resin particles and the metal oxide-containing resin particles may be mixed in a solvent as described later.

  In addition, the polymer during the production of the metal oxide-containing resin particles and the polymer during the production of the ultraviolet absorber-containing resin particles are mixed so as to fall within the above range, and washed and dried in the same manner as described above. It can also be mixed by crushing.

  The ultraviolet shielding agent of this embodiment can be obtained by the above steps.

[Ultraviolet shielding agent-containing dispersion]
The ultraviolet shielding agent-containing dispersion liquid of this embodiment is a dispersion liquid obtained by dispersing the above-described ultraviolet absorber-containing resin particles and metal oxide-containing resin particles in a dispersion medium. The ultraviolet absorbent-containing resin particles and the metal oxide-containing resin particles are 1% by mass to 80% by mass in total in the dispersion, preferably 20% by mass to 70% by mass, more preferably 30% by mass. The content is 60% by mass or less. By dispersing each resin particle in a dispersion medium within the above range, an ultraviolet shielding agent-containing dispersion liquid having excellent ultraviolet shielding effect, stable dispersibility of the ultraviolet shielding agent in the dispersion, and excellent temporal stability. Can be obtained.

  The dispersion medium may be any solvent that can disperse the above resin particles. For example, water, alcohols such as methanol, ethanol, 2-propanol, butanol, octanol, ethyl acetate, butyl acetate, ethyl lactate, propylene Glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate, esters such as γ-butyrolactone, diethyl ether, ethylene glycol monomethyl ether (methyl cellosolve), ethylene glycol monoethyl ether (ethyl cellosolve), ethylene glycol monobutyl ether (butyl cellosolve), Ethers such as diethylene glycol monomethyl ether and diethylene glycol monoethyl ether, acetone, methyl ethyl ketone, methyl isobutyl ketone , Ketones such as acetylacetone and cyclohexanone, aromatic hydrocarbons such as benzene, toluene, xylene and ethylbenzene, amides such as dimethylformamide, N, N-dimethylacetamide and N-methylpyrrolidone, dimethylpolysiloxane and methylphenylpoly Chain polysiloxanes such as siloxane and diphenylpolysiloxane, cyclic polysiloxanes such as octamethylcyclotetrasiloxane, decamethylcyclopentasiloxane, dodecamethylcyclohexanesiloxane, amino-modified polysiloxane, polyether-modified polysiloxane, alkyl-modified poly Modified polysiloxanes such as siloxane and fluorine-modified polysiloxane are preferably used, and one of these solvents or a mixture of two or more of them can be used.

  In this dispersion, the ultraviolet absorber-containing resin particles and metal oxide-containing resin particles are mixed with a solvent, and if necessary, a dispersant and a water-soluble binder are mixed. Then, a sand mill and zirconia beads are added to the mixture. It can be obtained by carrying out a dispersion treatment using a dispersing machine such as a bead mill, a ball mill, or a homogenizer, or a mixer, and dispersing the ultraviolet absorbent-containing resin particles and the metal oxide-containing resin particles in a solvent.

  Examples of the ultraviolet shielding agent-containing dispersion liquid include a silicone dispersion liquid dispersed in silicone and an aqueous dispersion liquid dispersed in water.

[Silicone dispersion containing UV screening agent]
The ultraviolet shielding agent-containing silicone dispersion of the present embodiment comprises the above-described ultraviolet absorber-containing resin particles and metal oxide-containing resin particles in a total mass of 1% by mass to 80% by mass, preferably 20% by mass to 70%. It is a silicone dispersion formed by dispersing in silicone of not more than mass%, more preferably not less than 30 mass% and not more than 60 mass%.

  The silicone is not particularly limited as long as it is a cyclic silicone or a linear silicone having a structural skeleton represented by the formula (1). Examples of such silicone include dimethylpolysiloxane, methylphenylpolysiloxane, hexamethylcyclotrisiloxane, octamethylcyclotetrasiloxane, decamethylcyclopentasiloxane, and methyltrimethicone.

式（１）のＸは１〜２０００であれば、化粧料として好適に使用することができる。

If X of Formula (1) is 1-2000, it can be used suitably as cosmetics.

  The dispersant is not particularly limited as long as the ultraviolet absorber-containing resin particles and the metal oxide-containing resin particles can be dispersed in silicone. For example, polyether-modified silicone, polyglycerin-modified silicone, amino-modified silicone, phenyl Examples include modified silicone, alkyl-modified silicone, carbinol-modified silicone, and dimethyl silicone. The dispersant is preferably mixed in an amount of 1% by mass to 50% by mass with respect to the total mass of the ultraviolet absorber-containing resin particles and the metal oxide-containing resin particles.

Further, natural oil, humectant, thickener, fragrance, preservative and the like may be further mixed with the dispersion obtained by dispersing the silicone and the dispersant with a sand mill or a homogenizer.
By adjusting within the above range, even if this ultraviolet screening agent-containing silicone-based dispersion is used alone or mixed with cosmetics, transparency can be sufficiently secured when spread and applied to the skin. it can.

[Ultraviolet shielding agent-containing aqueous dispersion]
The ultraviolet shielding agent-containing aqueous dispersion of this embodiment is an ultraviolet shielding agent-containing aqueous dispersion obtained by dispersing the above-described ultraviolet absorber-containing resin particles and metal oxide-containing resin particles in a dispersion medium containing alcohols. The total content of the ultraviolet absorber-containing resin particles and the metal oxide-containing resin particles is 1% by mass to 80% by mass, more preferably 20% by mass to 70% by mass, and even more preferably 30% by mass. This is an aqueous dispersion containing not less than 60% by mass and not less than 5% by mass and not more than 20% by mass of alcohol.

  In this aqueous dispersion, the water-soluble polymer is further added 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 0.01% by mass and more. An aqueous dispersion containing 3% by mass or less may be used. In this case, the content of each component is adjusted so that the total content of each component of the ultraviolet absorber-containing resin particles, metal oxide-containing resin particles, alcohols and water-soluble polymer does not exceed 100% by mass. There is a need.

  Examples of alcohols include monohydric alcohols having 1 to 6 carbon atoms such as ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, glycerin, 1,3-butylene glycol, propylene glycol, and sorbitol, or polyvalent ones. Examples include alcohols, and among them, monohydric alcohols, particularly ethanol is preferable.

When this aqueous dispersion does not contain a water-soluble polymer, the content of alcohol is preferably 5% by mass or more and 20% by mass or less, more preferably 10% by mass or more and 20% by 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 dispersion of the ultraviolet shielding agent can be improved, which is preferable.

In the case where the aqueous dispersion liquid contains a water-soluble polymer, the water-soluble polymer is not particularly limited as long as it can be used for cosmetics, but is not limited to gum arabic, sodium alginate, casein, carrageenan, galactan, carboxy. Vinyl 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 And methyl hydroxypropyl cellulose. These water-soluble polymers may be used alone or in combination of two or more.
The water-soluble polymer has a role as a dispersant and a viscosity modifier, and when added, the dispersibility and stability over time of the ultraviolet shielding agent in the aqueous dispersion are also improved.

When the aqueous dispersion contains a water-soluble polymer, the content of 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 alcohol content when the aqueous dispersion contains a water-soluble polymer is 5 mass% or more and 20 mass% or less is that the content of alcohol is less than 5 mass%. Since the amount is too small, the water-soluble polymer cannot be uniformly infiltrated into the alcohols and will swell non-uniformly with moisture.As a result, the dispersibility of the UV shielding agent is reduced, making it difficult to handle, Furthermore, the stability with time of the aqueous dispersion decreases, which is not preferable. On the other hand, when the content exceeds 20% by mass, the viscosity of the entire aqueous dispersion is increased, the dispersion stability of the ultraviolet shielding agent is decreased, and the temporal stability of the aqueous dispersion is also decreased.

This ultraviolet shielding agent-containing aqueous dispersion is prepared by mixing the ultraviolet absorber-containing resin particles and the metal oxide-containing resin particles with a solvent containing alcohol or a mixture containing alcohols and a water-soluble polymer, It can be obtained by mixing and dispersing water. The amount of water may be appropriately adjusted, but a range of 15% by mass to 94% by mass is preferable.
By adjusting within the above range, it is possible to obtain an ultraviolet shielding agent-containing aqueous dispersion that can sufficiently ensure transparency when used alone or mixed with cosmetics when spread and applied to the skin. .

[Cosmetics]
The cosmetic of the present embodiment is a cosmetic containing one or both of the ultraviolet shielding agent and the ultraviolet shielding agent-containing dispersion described above in an amount of 1% by mass or more and 60% by mass or less in terms of the ultraviolet shielding agent. By containing the ultraviolet shielding agent within the above range, there is no fear of whitening, a sufficient transparency can be ensured, and there is no roughness or the like, and the usability is excellent.

  This cosmetic can be obtained by conventionally blending one or more of the above-described ultraviolet shielding agent and the ultraviolet shielding agent-containing dispersion into an emulsion, cream, foundation, lipstick, blusher, eye shadow, or the like. it can.

  Furthermore, by blending either or both of the above-described ultraviolet shielding agent and ultraviolet shielding agent-containing dispersion into a water-based cosmetic such as lotion or sunscreen gel, which has been difficult to formulate in the past, ultraviolet shielding ability Thus, it is possible to obtain a water-based cosmetic excellent in transparency and use feeling.

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

  As described above, according to the ultraviolet shielding agent of the present embodiment, the ultraviolet absorber-containing resin particles having an average particle size of 0.1 μm or more and 1 μm or less, and the ultraviolet light having an average particle size of 0.1 μm or more and 1 μm or less. By mixing the metal oxide-containing resin particles having shielding ability with the mass ratio of the organic ultraviolet absorber and the metal oxide so as to be in the range of 1:45 to 3: 1, the organic ultraviolet ray is obtained. A synergistic effect in the ultraviolet shielding ability of both the absorbent and the metal oxide particles can be obtained, and the ultraviolet shielding effect at a wavelength of 380 nm to 400 nm is enhanced.

  Moreover, since the organic ultraviolet absorber and the metal oxide are fixed in the resin, high light stability can be obtained. Specifically, when exposed to ultraviolet rays, the organic ultraviolet absorber may crystallize due to the influence of metal ions, which may cause deterioration of the cosmetics, discoloration, and deterioration in the feeling of use. With the shielding agent, such deterioration can be suppressed, and the quality of the cosmetic can be stabilized.

In addition, since the ultraviolet shielding agent of this embodiment does not require the organic ultraviolet absorber to be dissolved in a specific solvent, it has been difficult to formulate in addition to the water-in-oil type (W / O type). It can be blended in water-based cosmetics such as oil-in-water type (O / W type), lotion and sunscreen gel. Therefore, the freedom degree of cosmetics prescription can be raised.
In addition, since the average particle size of the ultraviolet absorber-containing resin particles and the metal oxide-containing resin particles is 0.1 μm or more and 1 μm or less, even when used in cosmetics, there is no rough feeling and excellent usability. Yes.

  In addition, since the resin contains a metal oxide with an average primary particle size of 0.003 μm or more and 0.1 μm or less, the transparency that is regarded as important in cosmetics is maintained without absorbing visible light. can do.

  Furthermore, by using the cosmetic of the present embodiment as a cosmetic ingredient, various cosmetics such as skin care cosmetics, makeup cosmetics, body care cosmetics and the like excellent in ultraviolet shielding ability, transparency, usability and safety are provided. Can do. Especially when used for skin care cosmetic whitening, makeup cosmetic base makeup, body care cosmetic sunscreen, etc. that require UV shielding ability, it has excellent UV shielding ability, transparency, feeling of use and safety. Cosmetics can be provided.

In addition, the ultraviolet shielding agent of this embodiment and the dispersion liquid containing it can be diverted to a weather-resistant paint or the like that requires an ultraviolet shielding function.
In addition, when used in fields other than cosmetics, there are many cases where the feeling of roughness, feeling of use, transparency, etc. that are regarded as important in cosmetics are not so much a problem, and the choice of dispersants and resins is widened. The degree of freedom of design blending can be increased.

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

[Production Example 1]
[Preparation of zinc oxide-containing resin particles]
200 parts by mass of zinc oxide fine particles (manufactured by Sumitomo Osaka Cement Co., Ltd., average primary particle size 0.02 μm), 188 parts by mass of methyl methacrylate, and 12 parts by mass of a phosphoric acid ester type surfactant are mixed, and a sand mill is used. Dispersion treatment was performed for 2 hours to obtain a monomer dispersion liquid in which zinc oxide fine particles were dispersed in methyl methacrylate.

  Next, 105.0 parts by mass of the obtained monomer (MMA) dispersion, 229.5 parts by mass of pure water, 0.5 parts by mass of sodium dodecylbenzenesulfonate, 14.0 parts by mass of ethylene glycol dimethacrylate, silicone-based antifoaming 1.0 part by mass of the agent was mixed and stirred at 6000 rpm for 10 minutes using a homogenizer to obtain an emulsion having a dispersed particle size D50 of 0.6 μm.

  Next, 320.0 parts by mass of the obtained emulsion, 79.856 parts by mass of pure water, and 0.144 parts by mass of potassium persulfate were mixed, transferred to a reactor equipped with a stirrer and a thermometer, and replaced with nitrogen at room temperature. It went for 1 hour. Subsequently, it heated up at 65 degreeC and hold | maintained for 3 hours, and the polymerization reaction was performed. Next, the polymerization reaction was stopped by cooling with ice, and the resulting polymer was washed with 2-propanol, further washed with pure water, and dried at 90 ° C. The dried product thus obtained was crushed with a hammer mill to obtain resin particles containing zinc oxide fine particles having an average particle size of 0.5 μm. The obtained resin particles were measured with TG-DTA (manufactured by Rigaku Corporation, Thermo Plus2 TG8120), and it was confirmed that the resin particles contained 50% by mass of zinc oxide.

[Production Example 2]
[Aqueous dispersion containing zinc oxide-containing resin particles]
25 parts by mass of the zinc oxide-containing resin particles obtained in Production Example 1, 7.5 parts by mass of ethanol, and 17.5 parts by mass of pure water were mixed to obtain an aqueous dispersion containing zinc oxide-containing resin particles. .

[Production Example 3]
[Preparation of avobenzone-containing resin particles]
Avobenzone (manufactured by DSM Nutrition Japan Co., Ltd., Pulsol (registered trademark) 1789) and 5 parts by mass of a phosphate ester type surfactant are added to and mixed with 85 parts by mass of methyl methacrylate, and a resin monomer solution is added. Produced.
Next, 105 mass parts of this resin monomer solution was added to 229.5 mass parts of pure water, 0.5 mass parts of sodium dodecylbenzenesulfonate, 14.0 mass parts of ethylene glycol dimethacrylate, 1.0 mass of silicone antifoaming agent. The parts were mixed and stirred at 10,000 rpm for 10 minutes using a homogenizer to prepare an emulsion.

320.0 parts by mass of the above emulsion, 79.856 parts by mass of pure water, and 0.144 parts by mass of potassium persulfate were mixed, transferred to a reactor equipped with a stirrer and a thermometer, and replaced with nitrogen for 1 hour. It was.
Next, the temperature of the reaction solution after nitrogen substitution was raised to 65 ° C. and held at 65 ° C. for 3 hours to carry out a polymerization reaction. Thereafter, the polymerization reaction was stopped by cooling with ice, and the resulting polymer was washed with 2-propanol and pure water, and then dried at 90 ° C. The dried product thus obtained was crushed with a hammer mill to obtain resin particles containing avobenzone having an average particle size of 0.3 μm.
The mass of the recovered resin particles substantially coincided with the total mass of methyl methacrylate, avobenzone, and phosphate ester surfactant used for preparing the resin particles. Therefore, compounding of the manufacture example 4 or less was performed on the assumption that 10% by mass of avobenzone is contained in the resin particles.

[Production Example 4]
[Aqueous dispersion containing avobenzone-containing resin particles]
In Production Example 2, an aqueous dispersion containing avobenzone-containing resin particles was used in the same manner except that the avobenzone-containing resin particles obtained in Production Example 3 were used instead of the zinc oxide-containing resin particles obtained in Production Example 2. Got.

[Example 1]
20 parts by mass of the aqueous dispersion containing the zinc oxide-containing resin particles obtained in Production Example 2, 20 parts by mass of the aqueous dispersion containing the avobenzone-containing resin particles obtained in Production Example 4, and 1 sodium carboxymethylcellulose 0.5 parts by mass, 6.0 parts by mass of ethanol, and 2.5 parts by mass of glycerin were mixed. Next, the mixture was heated and stirred at 70 ° C. for 10 minutes to obtain a moisture gel containing zinc oxide-containing resin particles and avobenzone-containing resin particles (organic ultraviolet absorber: zinc oxide = 1: 5).

The obtained moisture gel was applied to a quartz plate in an amount of ² mg / cm ² , and the spectral transmittance and SPF value were measured using SPF analyzer UV-1000S (manufactured by Labsphere, USA). This spectral transmittance is shown in FIG. The SPF value was 66.8.

[Comparative Example 1]
20 mass parts of the aqueous dispersion containing the zinc oxide-containing resin particles obtained in Production Example 2 was used, while the aqueous dispersion containing the avobenzene-containing resin particles obtained in Production Example 4 was not used. In the same manner as in Example 1, a moisture gel containing zinc oxide-containing resin particles was produced.

  The SPF value and the spectral transmittance were measured in the same manner as in Example 1. This spectral transmittance is shown in FIG. The SPF value was 33.0.

[Comparative Example 2]
20 parts by mass of the aqueous dispersion containing the avobenzone-containing resin particles obtained in Production Example 4 was used, except that the aqueous dispersion containing the zinc oxide-containing resin particles obtained in Production Example 2 was not used. In the same manner as in Example 1, a moisture gel containing avobenzone-containing resin particles was obtained.

  The SPF value and the spectral transmittance were measured in the same manner as in Example 1. This spectral transmittance is shown in FIG. The SPF value was 40.5.

  From FIG. 1, the moisture gel containing the resin particles of both the zinc oxide-containing resin particles and the avobenzone-containing resin particles of Example 1 has an ultraviolet shielding rate of 380 nm to 400 nm in wavelength compared to the moisture gel containing individual resin particles. Excellent. Also, the SPF value was the highest in Example 1, and it was confirmed that the UV shielding ability was excellent.

Claims (3)

First resin particles containing an organic ultraviolet absorber and having an average particle size of 0.1 μm or more and 1 μm or less, and a metal oxide having an ultraviolet shielding ability, and having an average particle size of 0.1 μm or more and 1 μm or less An ultraviolet shielding agent comprising the second resin particles,
The organic ultraviolet absorber and the metal oxide are contained in a mass ratio of 1:45 to 3: 1.   An ultraviolet shielding agent-containing dispersion liquid comprising the ultraviolet shielding agent according to claim 1.   A cosmetic comprising one or both of the ultraviolet shielding agent according to claim 1 and the ultraviolet shielding agent-containing dispersion according to claim 2.

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