Water-in-oil emulsion composition

Abstract

This water-in-oil emulsion composition contains a dibenzoylmethane derivative (A) and a metal oxide powder (B) hydrophobized with a non-silicone-based substance, but does not substantially contain elemental aluminum.

Description

Water-in-oil emulsion composition

[0001] The present disclosure relates to a water-in-oil emulsion composition.

[0002] Water-in-oil emulsion compositions such as cosmetics are known to have UV protection properties. These compositions generally contain a metal oxide powder whose surface has been hydrophobized as a UV scattering agent. The hydrophobizing agent often contains a silicone-based substance, which improves the dispersibility of the UV scattering agent and thereby enhances the UV protection properties of the composition (see, for example, Patent Document 1).

[0003] However, in recent years, in consideration of achieving the Sustainable Development Goals, there has been a demand to limit or avoid the use of silicone-based substances, which have been pointed out as having a burden on the environment, and the use of non-silicone-based substances as hydrophobic treatment agents has also been considered.

[0004] Furthermore, various ultraviolet absorbers have been investigated to improve the ultraviolet protection ability of water-in-oil emulsion compositions. Dibenzoylmethane derivatives are known as ultraviolet absorbers with high ultraviolet protection ability, particularly at high wavelengths (see, for example, Patent Document 2).

[0005] JP 2021-167286 A JP 2014-139228 A

[0006] In light of the above background, a formulation combining a metal oxide powder treated with a non-silicone hydrophobic treatment agent and a dibenzoylmethane derivative has been considered. However, it has been found that some combinations of metal oxide powder treated with a non-silicone hydrophobic treatment agent and a dibenzoylmethane derivative cause discoloration. When a discolored composition is applied to a surface, the original color of the surface is damaged, which is inconvenient.

[0007] In view of the above, an object of one aspect of the present disclosure is to provide a water-in-oil emulsion composition having UV protection capability, which is environmentally friendly and less likely to cause discoloration.

[0008] One aspect of the present disclosure for solving the above problems is a water-in-oil emulsion composition that contains (A) a dibenzoylmethane derivative and (B) a metal oxide powder that has been hydrophobized with a non-silicone substance, and that is substantially free of aluminum element.

[0009] According to one aspect of the present disclosure, it is possible to provide a water-in-oil emulsion composition having UV protection properties, which is environmentally friendly and less likely to cause discoloration.

[0010] <Water-in-oil emulsion composition> One embodiment of the present disclosure is a water-in-oil (W / O) emulsion composition that contains (A) a dibenzoylmethane derivative and (B) a metal oxide powder that has been hydrophobized with a non-silicone substance, and that is substantially free of aluminum element.

[0011] The use of the water-in-oil composition according to this embodiment is not particularly limited, but it is preferably used in the fields of cosmetics, quasi-drugs, and personal care products. Furthermore, the water-in-oil composition according to this embodiment is suitable as an external preparation or a skin application agent, particularly as a cosmetic. More specifically, it may be a sunscreen for UV protection, or a cosmetic with enhanced UV protection function, such as a basic cosmetic product such as foundation, or a makeup cosmetic product. Furthermore, the water-in-oil emulsion composition according to this embodiment may be in a solid or semi-solid form. It may also be provided in a form known as a gel, jelly, or cream.

[0012] <Ultraviolet Absorber> <<(A) Dibenzoylmethane Derivative>> Dibenzoylmethane derivatives are ultraviolet absorbers that exhibit high ultraviolet protection capabilities, and can provide such capabilities even in small amounts. Dibenzoylmethane derivatives can exhibit high ultraviolet absorption capabilities, particularly in the long wavelength region, specifically in wavelengths of 300 nm or more and 400 nm or less.

[0013] Specific examples of dibenzoylmethane derivatives include t-butyl methoxydibenzoylmethane (i.e., 4-tert-butyl-4'-methoxydibenzoylmethane), 2-methyldibenzoylmethane, 4-methyldibenzoylmethane, 4-isopropyldibenzoylmethane, 4-tert-butyldibenzoylmethane, 2,4-dimethyldibenzoylmethane, 2,5-dimethyldibenzoylmethane, 4,4'-diisopropyldibenzoylmethane, 4,4'-dimethoxydibenzoylmethane, ... Examples of suitable tert-butyl-4'-methoxydibenzoylmethane include 2-methyl-5-tert-butyl-4'-methoxydibenzoylmethane, 2,4-dimethyl-4'-methoxydibenzoylmethane, 2,6-dimethyl-4-tert-butyl-4'-methoxydibenzoylmethane, 1-(4-tert-butylphenyl)-3-(2-hydroxyphenyl)propane-1,3-dione, and 1-(4-methoxy-1-benzofuran-5-yl)-3-phenylpropane-1,3-dione. Of these, t-butylmethoxydibenzoylmethane is preferred because even a small amount can provide particularly high UV protection ability.

[0014] The content of the (A) dibenzoylmethane derivative may be preferably 0.1% by mass or more and 10% by mass or less, more preferably 0.5% by mass or more and 8% by mass or less, and even more preferably 1% by mass or more and 5% by mass or less, relative to the total amount of the water-in-oil emulsion composition. When the content of the dibenzoylmethane derivative is 0.1% by mass or more, UV protection ability, particularly UV protection ability at long wavelengths, can be improved. Furthermore, when the content of the dibenzoylmethane derivative is 10% by mass or less, well-balanced UV protection ability can be obtained across the entire UV wavelength range. Furthermore, an excessively large amount of polar oil can be avoided, and the deterioration of the stability of the properties of the water-in-oil emulsion composition can also be suppressed.

[0015] <<UV Absorbers Other Than Dibenzoylmethane Derivatives>> The water-in-oil emulsion composition according to this embodiment may contain an UV absorber other than a dibenzoylmethane derivative. Examples of the UV absorber other than a dibenzoylmethane derivative include β,β-diphenylacrylate derivatives, salicylic acid derivatives, cinnamic acid derivatives, benzoic acid derivatives, benzophenone derivatives, benzylidene camphor derivatives, phenylbenzimidazole derivatives, triazine derivatives, phenylbenzotriazole derivatives, anthranil derivatives, imidazoline derivatives, benzalmalonate derivatives, and 4,4-diarylbutadiene derivatives.

[0016] Examples of β,β-diphenylacrylate derivatives include octocrylene. Examples of salicylic acid derivatives include ethylhexyl salicylate (ethylhexyl salicylate or octyl salicylate), homosalate, dipropylene glycol salicylate, and TEA salicylate. Of these, ethylhexyl salicylate is preferred. Examples of cinnamic acid derivatives include ethylhexyl methoxycinnamate (octyl methoxycinnamate), isopropyl methoxycinnamate, isoamyl methoxycinnamate, cinoxate, DEA methoxycinnamate, diisopropyl methylcinnamate, glyceryl-ethylhexanoate-dimethoxycinnamate, and di-(2-ethylhexyl)-4'-methoxybenzalmalonate. Of these, ethylhexyl methoxycinnamate is preferred.

[0017] Examples of benzoic acid derivatives include ethyl p-aminobenzoate (PABA), ethyl-dihydroxypropyl PABA, ethylhexyl-dimethyl PABA, glyceryl PABA, PEG-25-PABA, and diethylaminohydroxybenzoylhexyl benzoate. Examples of benzophenone derivatives include benzophenone-1, benzophenone-2, benzophenone-3 or oxybenzone, benzophenone-4, benzophenone-5, benzophenone-6, benzophenone-8, benzophenone-9, and benzophenone-12. Examples of benzylidene camphor derivatives include 3-benzylidene camphor, 4-methylbenzylidene camphor, benzylidene camphorsulfonic acid, benzalkonium camphor methosulfate, terephthalidene discamphorsulfonic acid, and polyacrylamidomethyl benzylidene camphor. Examples of phenylbenzimidazole derivatives include phenylbenzimidazole sulfonic acid and disodium phenyldibenzimidazole tetrasulfonate. Examples of triazine derivatives include anisotriazine (bisethylhexyloxyphenol methoxyphenyl triazine), ethylhexyl triazone, diethylhexylbutamido triazone, and 2,4,6-tris(diisobutyl-4'-aminobenzalmalonate)-s-triazine. Examples of phenylbenzotriazole derivatives include drometrizole trisiloxane and methylenebis(benzotriazolyltetramethylbutylphenol). Examples of anthranil derivatives include menthyl anthranilate. Examples of imidazoline derivatives include 2-ethylhexyl ethylhexyl dimethoxybenzylidene dioxoimidazolidinepropionate. Examples of benzalmalonate derivatives include polyorganosiloxanes having benzalmalonate functional groups. Examples of 4,4-diarylbutadiene derivatives include 1,1-dicarboxy(2,2'-dimethylpropyl)-4,4-diphenylbutadiene.

[0018] The above-mentioned UV absorbers other than dibenzoylmethane derivatives can be used alone or in combination of two or more. As a combination of UV absorbers, a combination of a dibenzoylmethane derivative with octocrylene and ethylhexyl salicylate, or a combination of a dibenzoylmethane derivative with ethylhexyl methoxycinnamate is preferred. By using the above combination, the wavelength range in which the UV absorber exhibits its UV absorption ability can be broadened compared to the case of using only a dibenzoylmethane derivative.

[0019] The content of the dibenzoylmethane derivative may be preferably 5% by mass to 50% by mass, more preferably 10% by mass to 40% by mass, based on the total amount of UV absorbers in the water-in-oil emulsion composition. Within this range, the UV absorption ability of the water-in-oil emulsion composition can be increased, particularly in the long wavelength region, and well-balanced UV absorption ability can be obtained across the entire UV wavelength range.

[0020] <(B) Metal oxide powder hydrophobized with a non-silicone-based substance> The water-in-oil emulsion composition according to this embodiment further contains a hydrophobized metal oxide powder. This hydrophobized metal oxide powder is a metal oxide powder whose surface has been treated with a hydrophobizing agent, making the surface hydrophobic. The hydrophobized metal oxide powder preferably has UV protection capability, specifically, UV scattering capability, i.e., is an UV scattering agent. Furthermore, since a non-silicone-based substance (described in detail below) is used for the hydrophobization, the resulting metal oxide powder is (B) hydrophobized with a non-silicone-based substance.

[0021] <<Metal Oxide Powder>> The hydrophobized metal oxide powder contained in the water-in-oil emulsion composition as an UV scattering agent may be in particulate form. In this case, the average primary particle diameter of the metal oxide powder is not particularly limited, and may be 5 nm or more, 10 nm or more, or 15 nm or more, and may be 200 nm or less, 100 nm or less, or 50 nm or less. Note that the "average primary particle diameter" in this specification may be determined, for example, as the diameter of a circle equivalent to the projected area of ​​primary particles in an SEM image.

[0022] Specific examples of metal oxide powders include titanium oxide, zinc oxide, cerium oxide, iron oxide, and tungsten oxide. These metal oxide powders can be used alone or in combination. Among these, titanium oxide and zinc oxide are preferred due to their high UV scattering ability. Furthermore, titanium oxide is preferred due to its high scattering ability for UV rays in the relatively short wavelength range, particularly UV rays from 280 nm to 320 nm. Furthermore, titanium oxide, when combined with the above-mentioned dibenzoylmethane derivative, can impart UV protection ability over a wide wavelength range to the water-in-oil emulsion composition. Furthermore, the use of titanium oxide as the metal oxide powder can improve the transparency of the resulting water-in-oil emulsion composition. The "transparency" of a water-in-oil emulsion composition refers to the transparency when spread on a surface to be applied. Low transparency can cause the surface to appear whitish, resulting in a so-called whitish appearance. This is particularly inconvenient when the surface to be applied is skin, a phenomenon that users wish to avoid.

[0023] Furthermore, since the water-in-oil emulsion composition is substantially free of zinc oxide, the transparency of the water-in-oil emulsion composition can be improved. In this specification, the expression "substantially free of" a specific component means that unintentional contamination with aluminum element is permitted during the raw material acquisition process and / or production process.

[0024] <<Surface Treatment>> As described above, the hydrophobized metal oxide powder has a surface that has been made hydrophobic by treatment with a hydrophobizing agent. More specifically, a layer of the hydrophobizing agent may be formed entirely or partially on the surface of the metal oxide powder particles. The hydrophobized metal oxide powder is dispersed mainly in the oil phase of the water-in-oil emulsion composition.

[0025] The hydrophobic treatment of the metal oxide powder is a treatment to introduce hydrophobic groups onto the particle surfaces of the metal oxide powder or to form a coating layer of a hydrophobic treatment agent entirely or partially on the particle surfaces of the metal oxide powder. The hydrophobic treatment may be carried out by a wet method using a solvent, a gas phase method, a mechanochemical method, or the like.

[0026] In the above hydrophobic treatment, a non-silicone substance is used as the hydrophobic treatment agent. Here, the non-silicone substance refers to a substance other than a silicone substance. By using a non-silicone substance as the hydrophobic treatment agent, the silicone content in the water-in-oil emulsion composition can be reduced, resulting in a composition with a reduced environmental burden, which can contribute to the achievement of the Sustainable Development Goals. In this specification, the term "silicone substance" refers to a substance based on organopolysiloxane, and includes silicone oil, silicone surfactant, silicone rubber, silicone resin, etc.

[0027] Specific examples of non-silicone hydrophobic treatment agents include alkyl phosphate esters, higher fatty acids, higher alcohols, higher fatty acid esters, dextrin fatty acid esters, metal soaps, higher hydrocarbons, etc. Among these, alkyl phosphate esters are preferred.

[0028] As the alkyl phosphate ester, monoalkyl phosphate is preferred. Furthermore, as the alkyl phosphate ester, higher alkyl phosphate esters, i.e., phosphate esters having an alkyl group having 6 or more carbon atoms, are preferred, with those having a linear or branched alkyl group having 8 to 30 carbon atoms being more preferred, and those having a linear alkyl group having 10 to 20 carbon atoms being even more preferred. Furthermore, the alkyl phosphate ester may be in the form of an ester or a salt thereof (an alkyl phosphate salt or an alkyl phosphate ester salt). Specific examples of alkyl phosphate esters include cetyl phosphate (monocetyl phosphate), octyl phosphate, decyl phosphate (monodecyl phosphate), lauryl phosphate (dodecyl phosphate), myristyl phosphate, cetearyl phosphate, and stearyl phosphate, among which cetyl phosphate is particularly preferred. Metal oxide powders treated with a hydrophobic treatment agent containing cetyl phosphate exhibit high dispersibility in compositions, thereby imparting UV protection comparable to that achieved with a hydrophobic treatment agent containing a silicone substance. Cetyl phosphate is also preferred from the perspective of promoting environmental impact reduction.

[0029] Examples of the higher fatty acids include stearic acid, isostearic acid, myristic acid, etc. Examples of the dextrin fatty acid esters include dextrin palmitate, etc.

[0030] The above hydrophobic treatment agents may be used singly or in combination of two or more.

[0031] In addition to the hydrophobic treatment, the surface of the metal oxide powder may be treated with a hydrophilic treatment agent. In this case, the hydrophilic treatment agent may be mixed with the hydrophobic treatment agent in advance, and the metal oxide powder may be surface-treated using the mixed treatment agent. Alternatively, the surface of the metal oxide powder may be treated with a hydrophilic treatment agent (hydrophilic treatment) and then treated with a hydrophobic treatment agent (hydrophobic treatment). In this specification, the hydrophobic treatment agent and the hydrophilic treatment agent may be collectively referred to as surface treatment agents.

[0032] The hydrophilic treatment agent may also be a non-silicone-based substance. Specifically, the hydrophilic treatment agent may be an inorganic silicate compound, a metal hydroxide, or the like. Examples of inorganic silicate compounds include untreated silica. Examples of metal oxides include magnesium hydroxide, etc. Among these, untreated silica is preferred as the hydrophilic treatment agent. When untreated silica is used, the particle surfaces of the metal oxide powder are more reliably coated, making it difficult for metal ions in the metal oxide powder to precipitate. Furthermore, the dispersibility of the metal oxide powder can be further improved, thereby improving the usability of the water-in-oil emulsion composition.

[0033] The above hydrophilic treatment agents can be used either individually or in combination of two or more.

[0034] In addition, when the surface treatment agent contains a hydrophobic treatment agent and a hydrophilic treatment agent, and when an alkyl phosphate ester is used as the hydrophobic treatment agent, it is preferable to use untreated silica as the hydrophilic treatment agent. Furthermore, in this case, it is preferable to perform a hydrophilic treatment on the particle surface of the metal oxide powder to form a silica coating, and then perform a hydrophobic treatment to form an alkyl phosphate ester coating, thereby forming a double coating on the particle surface of the metal oxide powder. By forming the silica coating first, the alkyl phosphate ester coating can be formed more uniformly and more reliably.

[0035] When a metal oxide powder hydrophobized with a non-silicone substance is contained as an ultraviolet scattering agent, the content of the metal oxide powder hydrophobized with a non-silicone substance (B) may be preferably 0.1% by mass or more and 30% by mass or less, more preferably 1% by mass or more and 25% by mass or less, even more preferably 3% by mass or more and 20% by mass or less, and particularly preferably 4% by mass or more and 13% by mass or less, relative to the total amount of the water-in-oil emulsion composition. When the content of the metal oxide powder hydrophobized with a non-silicone substance as an ultraviolet scattering agent is 0.1% by mass or more, the water-in-oil emulsion composition can exhibit sufficient ultraviolet protection function, and when it is 30% by mass or less, the dispersion state of the ultraviolet scattering agent in the water-in-oil emulsion composition is improved, and the transparency of the water-in-oil emulsion composition is also improved.

[0036] <Regarding Aluminum Element> Furthermore, in this embodiment, the water-in-oil emulsion composition is substantially free of aluminum element. Here, the meaning of the term "aluminum element" includes aluminum alone and aluminum ions. Furthermore, "the water-in-oil emulsion composition is substantially free of aluminum element" means that aluminum element is allowed to be present in some form in the water-in-oil emulsion composition due to unintentional contamination of aluminum element in the raw material acquisition process and / or production process. Furthermore, "the water-in-oil emulsion composition is substantially free of aluminum element" means that the content of aluminum element (content of aluminum alone or as aluminum ions) is preferably 1% by mass or less, more preferably 0.5% by mass or less, and even more preferably 0.05% by mass or less, relative to the total amount of the water-in-oil emulsion composition. Furthermore, it is particularly preferable that the content of aluminum element is 0% by mass relative to the total amount of the water-in-oil emulsion composition.

[0037] As described above, the water-in-oil emulsion composition according to this embodiment contains a dibenzoylmethane derivative as an ultraviolet absorber. However, the present inventors have discovered that the presence of aluminum, even in amounts comparable to those found in surface treatment agents for ultraviolet scattering agents, can cause discoloration that can affect the appearance of the final water-in-oil emulsion composition. This is thought to be due to the formation of a complex between the dibenzoylmethane derivative and aluminum ions in the composition, resulting in a red color. When the water-in-oil emulsion composition is used as a skin application agent, this discoloration is undesirable for the user, as it results in the skin itself appearing discolored. In contrast, discoloration (redness) can be prevented by using a surface treatment agent for a metal oxide powder that is substantially free of aluminum.

[0038] In contrast, according to the present embodiment, the water-in-oil emulsion composition is substantially free of aluminum element, and therefore discoloration caused by the interaction between the dibenzoylmethane derivative and aluminum element can be prevented.

[0039] Specifically, the surface treatment agent of the UV scattering agent is substantially free of aluminum element. Also, the oil phase or the water phase of the water-in-oil emulsion composition is substantially free of aluminum compounds or aluminum metal. The meaning of "substantially free" is as described above.

[0040] In this specification, discoloration may be evaluated immediately after preparation of the final product (water-in-oil emulsion composition), but can also be evaluated by observing the color change after a predetermined time has elapsed. Furthermore, it is preferable to evaluate by observing the color change after a predetermined time has elapsed at a high temperature. "After a predetermined time" may refer to several days to several weeks after preparation of the product. Furthermore, "high temperature" refers to a temperature above room temperature (15°C to 25°C), and may be 30°C or higher, 40°C or higher, or 50°C or higher. Evaluation of discoloration of the water-in-oil emulsion composition according to this embodiment can be, for example, evaluation of the presence or absence of red discoloration after storage at 50°C for 4 weeks after preparation.

[0041] <Organic modified clay mineral> The organic modified clay mineral can function as an emulsifier that promotes the emulsification of the oil-based component and the aqueous component. More specifically, by adding the organic modified clay mineral, the oil-based component can be well thickened or gelled, and the gelled state of the oil phase can be maintained over time, so that the dispersion state of the aqueous phase is also stable. This allows the properties of the water-in-oil type to be stably maintained for a long period of time.

[0042] The organically modified clay mineral may be a cationically modified clay mineral obtained by treating a layered clay mineral such as bentonite, laponite, hectorite, montmorillonite, or aluminum magnesium silicate with a quaternary ammonium salt-type cationic surfactant. Specific examples of organically modified clay minerals include disteardimonium hectorite (dimethyl disteardimonium hectorite), dimethyl alkyl ammonium hectorite, benzyl dimethyl stearyl ammonium hectorite, and aluminum magnesium silicate treated with distearyl dimethyl ammonium chloride. Of these, disteardimonium hectorite is preferred because of its high emulsifying function. The above organically modified clay minerals can be blended alone or in combination of two or more.

[0043] The content of the organically modified clay mineral may be preferably 0.05% by mass or more and 10% by mass or less, more preferably 0.1% by mass or more and 5% by mass or less, based on the total amount of the water-in-oil emulsion composition. When the content of the organically modified clay mineral is 0.05% by mass or more, the properties of the water-in-oil emulsion can be stabilized. In a composition with stable properties, the UV scattering agent is well dispersed, thereby improving UV protection ability. When titanium oxide is used as the metal oxide powder, UV protection ability in the short wavelength range can be improved. Furthermore, when the content of the organically modified clay mineral is 5% by mass or less, for example, when the water-in-oil emulsion composition is used as a skin application agent, a good feel with little stickiness is obtained, and the composition spreads lightly on the skin, improving usability.

[0044] <Regarding Silicone-Based Substances> As described above, the hydrophobic treatment agent for the metal oxide powder hydrophobized with a non-silicone-based substance does not contain a silicone-based substance. Furthermore, in this embodiment, it is preferable that the entire water-in-oil composition is also substantially free of silicone-based substances. "Silicone-based substances" refers to organopolysiloxane-based substances, including silicone oil, silicone rubber, silicone-based activators, silicone resins, etc. By substantially freeing the entire water-in-oil composition from silicone-based substances, silicone-free or reduced-silicone products can be provided, thereby reducing the burden on the environment and contributing to the realization of a sustainable society. The meaning of "substantially free" is as described above. Furthermore, "the water-in-oil emulsion composition is substantially free of silicone-based substances" refers to the content of silicone-based substances being preferably 1% by mass or less, more preferably 0.5% by mass or less, and even more preferably 0.05% by mass or less, relative to the total amount of the water-in-oil emulsion composition. Furthermore, it is particularly preferable that the content of silicone-based substances be 0% by mass relative to the total amount of the water-in-oil emulsion composition.

[0045] In particular, it is preferable that the water-in-oil emulsion composition is substantially free of silicone oil as an oily component. The meaning of "substantially free" is as described above. The phrase "the water-in-oil emulsion composition is substantially free of silicone oil" means that the content of silicone oil is preferably 1% by mass or less, more preferably 0.5% by mass or less, and even more preferably 0.05% by mass or less, relative to the total amount of the water-in-oil emulsion composition. Furthermore, it is particularly preferable that the content of silicone oil is 0% by mass, relative to the total amount of the water-in-oil emulsion composition.

[0046] It is also preferable that the surfactant does not substantially contain a silicone surfactant, and it is also preferable that the ultraviolet absorber does not substantially contain a silicone ultraviolet absorber such as a polysilicone derivative.

[0047] <Other Components> The water-in-oil emulsion composition according to this embodiment may contain other optional components in addition to the components described above. Examples of other components include water, which is the main component of the aqueous phase, as well as water-soluble alcohols, oily components other than UV absorbers, surfactants (including surface-active components), inorganic powders other than UV scattering agents, preservatives, stabilizers, pH adjusters, thickeners, pigments, antioxidants, anti-inflammatory agents, whitening agents, plant extracts, activators, blood circulation promoters, and antiseborrheic agents. When the water-in-oil emulsion composition is a skin application preparation, the other components may be components typically used in external compositions such as cosmetics and quasi-drugs, and may be added in amounts that do not interfere with the effects of this embodiment.

[0048] <<Main Component of Aqueous Phase>> Examples of water that can be used include purified water, ion-exchanged water, tap water, etc. Examples of water-soluble alcohols include lower alcohols, polyhydric alcohols, polyhydric alcohol polymers, alcohol alkyl ethers, alcohol ether esters, glycerin monoalkyl ethers, sugar alcohols, and derivatives thereof.

[0049] Examples of lower alcohols include ethanol, propanol, isopropanol, isobutyl alcohol, and t-butyl alcohol. Examples of polyhydric alcohols include dihydric alcohols (e.g., dipropylene glycol, 1,3-butylene glycol, ethylene glycol, trimethylene glycol, 1,2-butylene glycol, tetramethylene glycol, 2,3-butylene glycol, pentamethylene glycol, 2-butene-1,4-diol, hexylene glycol, and octylene glycol), trihydric alcohols (e.g., glycerin and trimethylolpropane), tetrahydric alcohols (e.g., pentaerythritol such as diglycerin and 1,2,6-hexanetriol), pentahydric alcohols (e.g., xylitol and triglycerin), and hexahydric alcohols (e.g., sorbitol and mannitol). Polyhydric alcohols also function as moisturizers.

[0050] <<Oil-Based Component>> Examples of oil-based components include hydrocarbon oils, ester oils, higher fatty acids, higher alcohols, liquid fats and oils, solid fats and oils, and waxes. Of these, hydrocarbon oils and ester oils are preferred, and it is more preferred to use hydrocarbon oils and ester oils in combination. The content of the oil-based component may be preferably 10% by mass or more and 60% by mass or less, more preferably 20% by mass or more and 50% by mass or less, based on the total amount of the water-in-oil emulsion composition.

[0051] Examples of hydrocarbon oils include isododecane, undecane, tridecane, isohexadecane, isoparaffin, liquid paraffin, ozokerite, squalane, pristane, paraffin, ceresin, squalene, petrolatum, microcrystalline wax, etc. Of these, isododecane, undecane, tridecane, and squalane are preferred.

[0052] Ester oils include octyl palmitate, myristyl myristate, isononyl isononanoate, isopropyl myristate, cetyl 2-ethylhexanoate, octyldodecyl myristate, isopropyl palmitate, butyl stearate, hexyl laurate, decyl oleate, hexyldecyl dimethyloctanoate, cetyl lactate, myristyl lactate, lanolin acetate, isocetyl stearate, isocetyl isostearate, cholesteryl 12-hydroxystearate, and ethyl di-2-ethylhexanoate. Glycol, Dipentaerythritol Fatty Acid Ester, N-Alkyl Glycol Monoisostearate, Neopentyl Glycol Dicaprate, Diisostearyl Malate, Glyceryl Di-2-heptylundecanoate, Trimethylolpropane Tri-2-ethylhexanoate, Trimethylolpropane Triisostearate, Pentaerythritol Tetra-2-ethylhexanoate, Glyceryl Tri-2-ethylhexanoate (Triethylhexanoin), Trimethylolpropane Triisostearate, Cetyl 2-ethyl Hexanoate, 2-ethylhexyl palmitate, diethylhexyl naphthalene dicarboxylate, alkyl benzoate (C12-15), cetearyl isononanoate, tri(caprylic / capric)glycerin, butylene glycol (dicaprylic / capric), glyceryl trimyristate, tri-2-heptylundecanoic acid glyceride, castor oil fatty acid methyl ester, oleyl oleate, cetostearyl alcohol acetoglyceride, 2-heptylundecyl palmitate, di-adipate isobutyl, N-lauroyl-L-glutamic acid 2-octyldodecyl ester, di-2-heptylundecyl adipate, ethyl laurate, di-2-ethylhexyl sebacate, 2-hexyldecyl myristate, 2-hexyldecyl palmitate, 2-hexyldecyl adipate, diisopropyl sebacate, di-2-ethylhexyl succinate, ethyl acetate, butyl acetate, amyl acetate, triethyl citrate, 2-ethylhexyl p-methoxycinnamate, tripropylene glycol dipivalate, etc. These ester oils may be used alone or in combination of two or more.

[0053] Examples of liquid oils and fats include jojoba seed oil, avocado oil, camellia oil, turtle oil, macadamia nut oil, corn oil, mink oil, olive oil, rapeseed oil, egg yolk oil, sesame oil, persic oil, wheat germ oil, camellia oil, castor oil, linseed oil, safflower oil, cottonseed oil, perilla oil, soybean oil, peanut oil, tea seed oil, kaya oil, rice bran oil, Chinese tung oil, Japanese tung oil, germ oil, triglycerin, etc. Examples of solid oils and fats include cacao butter, coconut oil, hardened coconut oil, palm oil, horse tallow, beef tallow, mutton tallow, hardened beef tallow, palm kernel oil, lard, beef bone fat, Japan wax kernel oil, hardened oil, beef trotter fat, Japan wax, and hardened castor oil.

[0054] The above oily components can be used alone or in combination of two or more.

[0055] <<Surfactant>> The surfactant (including a surfactant-like component) acts as an emulsifier and can improve the stability of the emulsion system of the dosage form. The content of the surfactant may be preferably 0.5% by mass or more and 8% by mass or less, more preferably 1% by mass or more and 5% by mass or less, based on the total amount of the water-in-oil emulsion composition. The surfactant (including a surfactant-like component) may be any of cationic, anionic, nonionic, and amphoteric. Of these, it is preferable to use a nonionic surfactant. Specific examples of nonionic surfactants include sorbitan fatty acid esters such as sorbitan sesquiisostearate, sorbitan sesquioleate, sorbitan isostearate, and sorbitan palmitate; polyethylene glycol fatty acid esters such as PEG-8 diisostearate and PEG-10 diisostearate; polyglycerin fatty acid esters such as polyglyceryl-2 diisostearate and polyglyceryl-2 triisostearate; polyoxyethylene hydrogenated castor oils such as PEG-40 hydrogenated castor oil, PEG-60 hydrogenated castor oil, and PEG-100 hydrogenated castor oil; monoglycerin fatty acid esters such as glyceryl stearate and glyceryl oleate; and self-emulsifying propylene glycol stearate. Furthermore, examples of surfactant-like components include higher fatty acids such as isostearic acid. These surfactants can be used alone or in combination of two or more.

[0056] <<Inorganic Powder>> The inorganic powder other than the UV scattering agent is an inorganic powder that does not have a UV scattering function. Examples thereof include silica, talc, kaolin, mica, sericite, muscovite, phlogopite, synthetic mica, lepidolite, biotite, vermiculite, magnesium carbonate, calcium carbonate, barium silicate, calcium silicate, magnesium silicate, strontium silicate, metal tungstate, magnesium, zeolite, barium sulfate, calcined calcium sulfate (calcined gypsum), calcium phosphate, fluorapatite, hydroxyapatite, ceramic powder, metal soap, and boron nitride. Other examples include inorganic white pigments (e.g., titanium dioxide, zinc oxide, etc.), inorganic red pigments (e.g., iron oxide (red iron oxide), iron titanate, etc.), inorganic brown pigments (e.g., γ-iron oxide, etc.), inorganic yellow pigments (e.g., yellow iron oxide, ochre, etc.), inorganic black pigments (e.g., black iron oxide, low-order titanium oxide, etc.), inorganic purple pigments (e.g., mango violet, cobalt violet, etc.), inorganic green pigments (e.g., chromium oxide, chromium hydroxide, cobalt titanate, etc.), inorganic blue pigments (e.g., ultramarine, Prussian blue, etc.), pearl pigments (e.g., titanium oxide-coated mica, titanium oxide-coated bismuth oxychloride, titanium oxide-coated talc, colored titanium oxide-coated mica, bismuth oxychloride, fish scale foil, etc.), metal powder pigments (e.g., copper powder, etc.), organic pigments such as zirconium lake and barium lake, and natural colorants. These inorganic powders may be untreated or may be surface-treated (hydrophobized and / or hydrophilized). These inorganic powders may be used singly or in combination of two or more.

[0057] The content of inorganic powders other than the UV scattering agent may be preferably 1% by mass or more and 30% by mass or less, more preferably 5% by mass or more and 20% by mass or less, based on the total amount of the water-in-oil emulsion composition.

[0058] Experimental Examples are shown below. The components shown in Table 1 were mixed by a conventional method to produce composition samples of Examples 1 to 3 and Comparative Examples 1 to 3, which were then evaluated. Table 1 also shows the evaluation results.

[0059] <Protection Ability> In this example, the ultraviolet protection ability in the short wavelength region was mainly evaluated. The composition sample obtained in each example was applied to an S plate (5 cm x 5 cm V-grooved PMMA plate, SPFMASTER-PA01) at a concentration of 2 mg / cm ２ was dropped onto a plate in an amount of 100 ml, which was applied with a finger for 60 seconds and allowed to dry for 15 minutes. After this, the absorbance (290 nm) was measured using a spectrophotometer (U-3500, manufactured by Hitachi Corporation). The transmittance of the composition sample was T, and the transmittance measured for the uncoated plate was To. The absorbance (Abs) was calculated using the following formula: Abs = -log(T / To) The composition samples were evaluated using Example 1 as a control according to the following evaluation criteria: A: The absorbance was equal to or greater than the absorbance of Example 1. B: The absorbance was less than the absorbance of Example 1, and the difference in absorbance from Example 1 was 0.15 or less. C: The absorbance was less than the absorbance of Example 1, and the difference in absorbance from Example 1 was more than 0.15 and 0.19 or less. D: The absorbance was less than the absorbance of Example 1, and the difference in absorbance from Example 1 was more than 0.19.

[0060] <Transparency> A composition sample of each example was filled into a plastic cell with an optical path length of 10 mm and an optical path width of 10 mm, and the transmittance in the wavelength region of 500 nm was measured using a spectrophotometer (U-4100, manufactured by Hitachi Corporation). The composition samples were evaluated according to the following evaluation criteria, with Example 1 as a control. A: The transmittance was higher than that of Example 1. B: The transmittance was equivalent to that of Example 1. C: The transmittance was lower than that of Example 1.

[0061] <Discoloration> A composition sample of each example was stored at 50°C for 4 weeks, and the color was visually observed and compared with the color before storage. Evaluation was based on the following evaluation criteria. A: No discoloration was observed. B: Slight discoloration was observed. C: Significant discoloration was observed.

[0062]

[0063] ・PEG-8 diisostearate: Emalex 400DI-IS EX, manufactured by Nippon Emulsion Co., Ltd. ・Bisbutyldimethicone polyglyceryl-3: Silicone KF-6109, manufactured by Shin-Etsu Chemical Co., Ltd. ・Polyglyceryl-2 diisostearate: WOGEL-18DV, manufactured by Matsumoto Fine Chemical Co., Ltd. ・Titanium oxide / silica / cetyl phosphate: Titanium oxide whose particle surface is coated in this order with silica and cetyl phosphate and whose average primary particle size is 15 nm ・Titanium oxide / aluminum hydroxide / stearic acid: Titanium oxide whose particle surface is coated in this order with aluminum hydroxide and stearic acid and whose average primary particle size is 15 nm ・Titanium oxide / magnesium hydroxide / stearic acid: Titanium oxide whose particle surface is coated in this order with magnesium hydroxide and stearic acid and whose average primary particle size is 15 nm ・Zinc oxide / dextrin palmitate: Zinc oxide whose particle surface is coated with dextrin palmitate and whose average primary particle size is 25 nm The percentages in Table 1 are mass %.

[0064] As shown in Table 1, the composition samples (Examples 1 to 3) containing a dibenzoylmethane derivative and a metal oxide powder hydrophobized with a non-silicone substance and substantially no aluminum element were found to exhibit high UV protection without discoloration. Furthermore, by using titanium oxide surface-treated with silica and cetyl phosphate as the metal oxide powder hydrophobized with a non-silicone substance (Examples 1 and 2), it was found that UV protection was improved and transparency during application was also excellent. The composition sample of Comparative Example 1 did not discolor, but its UV protection was low due to the absence of a dibenzoylmethane derivative.

[0065] Similarly, composition samples of Examples 4 to 6 were also prepared and evaluated for discoloration.

[0066]

[0067] It was shown that the composition samples (Examples 4 to 6) containing a dibenzoylmethane derivative and a metal oxide powder that had been hydrophobized with a silicone-based substance, more specifically cetyl phosphate, and that were substantially free of aluminum element, did not cause discoloration.

[0068] Although the present disclosure has been described above based on specific embodiments and examples, these embodiments and examples are presented merely as examples, and the present disclosure is not limited to the above embodiments and examples. Various changes, modifications, substitutions, deletions, additions, combinations, etc. are possible within the scope of the present disclosure.

[0069] This application claims priority based on Japanese Patent Application No. 2023-222429, filed on December 28, 2023, the entire contents of which are incorporated herein by reference.

Claims

1. An oil-in-water emulsion composition containing (A) a dibenzoylmethane derivative and (B) a metal oxide powder hydrophobized with a non-silicone substance, and substantially free of aluminum element.

2. The oil-in-water emulsion composition according to claim 1, wherein the (A) dibenzoylmethane derivative contains t-butylmethoxydibenzoylmethane.

3. The oil-in-water emulsion composition according to claim 1, wherein the non-silicone substance contains monoalkyl phosphate.

4. The oil-in-water emulsion composition according to claim 3, wherein the non-silicone substance contains cetyl phosphate.

5. The oil-in-water emulsion composition according to claim 1 or 2, wherein the metal oxide powder is titanium oxide powder.

6. The oil-in-water emulsion composition according to claim 1 or 2, substantially free of silicone oil.

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