Classifications

• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61K—PREPARATIONS FOR MEDICAL, DENTAL OR TOILETRY PURPOSES
  • A61K8/00—Cosmetics or similar toiletry preparations
  • A61K8/02—Cosmetics or similar toiletry preparations characterised by special physical form
  • A61K8/04—Dispersions; Emulsions
  • A61K8/06—Emulsions
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61K—PREPARATIONS FOR MEDICAL, DENTAL OR TOILETRY PURPOSES
  • A61K8/00—Cosmetics or similar toiletry preparations
  • A61K8/18—Cosmetics or similar toiletry preparations characterised by the composition
  • A61K8/19—Cosmetics or similar toiletry preparations characterised by the composition containing inorganic ingredients
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61K—PREPARATIONS FOR MEDICAL, DENTAL OR TOILETRY PURPOSES
  • A61K8/00—Cosmetics or similar toiletry preparations
  • A61K8/18—Cosmetics or similar toiletry preparations characterised by the composition
  • A61K8/19—Cosmetics or similar toiletry preparations characterised by the composition containing inorganic ingredients
  • A61K8/29—Titanium; Compounds thereof
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61K—PREPARATIONS FOR MEDICAL, DENTAL OR TOILETRY PURPOSES
  • A61K8/00—Cosmetics or similar toiletry preparations
  • A61K8/18—Cosmetics or similar toiletry preparations characterised by the composition
  • A61K8/30—Cosmetics or similar toiletry preparations characterised by the composition containing organic compounds
  • A61K8/33—Cosmetics or similar toiletry preparations characterised by the composition containing organic compounds containing oxygen
  • A61K8/34—Alcohols
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61K—PREPARATIONS FOR MEDICAL, DENTAL OR TOILETRY PURPOSES
  • A61K8/00—Cosmetics or similar toiletry preparations
  • A61K8/18—Cosmetics or similar toiletry preparations characterised by the composition
  • A61K8/30—Cosmetics or similar toiletry preparations characterised by the composition containing organic compounds
  • A61K8/33—Cosmetics or similar toiletry preparations characterised by the composition containing organic compounds containing oxygen
  • A61K8/37—Esters of carboxylic acids
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61K—PREPARATIONS FOR MEDICAL, DENTAL OR TOILETRY PURPOSES
  • A61K8/00—Cosmetics or similar toiletry preparations
  • A61K8/18—Cosmetics or similar toiletry preparations characterised by the composition
  • A61K8/30—Cosmetics or similar toiletry preparations characterised by the composition containing organic compounds
  • A61K8/40—Cosmetics or similar toiletry preparations characterised by the composition containing organic compounds containing nitrogen
  • A61K8/44—Aminocarboxylic acids or derivatives thereof, e.g. aminocarboxylic acids containing sulfur; Salts; Esters or N-acylated derivatives thereof
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61Q—SPECIFIC USE OF COSMETICS OR SIMILAR TOILETRY PREPARATIONS
  • A61Q17/00—Barrier preparations; Preparations brought into direct contact with the skin for affording protection against external influences, e.g. sunlight, X-rays or other harmful rays, corrosive materials, bacteria or insect stings
  • A61Q17/04—Topical preparations for affording protection against sunlight or other radiation; Topical sun tanning preparations

Definitions

• the present invention relates to an oil-in-water emulsion composition.
• UV protective cosmetics have been developed that use inorganic powders as UV scattering agents instead of oil-soluble UV absorbers (e.g., Patent Document 2).
• Cosmetics that use a combination of inorganic powders and oil-soluble UV absorbers are also known (e.g., Patent Document 3).
• Patent Document 1 International Publication No. 2018/105040
• Patent Document 2 Japanese Patent Application Laid-Open No. 10-182344
• Patent Document 3 Japanese Patent Application Laid-Open No. 2009-102236
• the present invention relates to an oil-in-water emulsion composition
• an oil-in-water emulsion composition comprising component (A): an ionic surfactant, component (B): a hydrophobic amphiphilic substance, component (C): an oil agent that is liquid at 25°C other than component (B), component (D): an inorganic powder, and component (E): water, wherein the content of component (C) in the composition is 17% by mass or more and 50% by mass or less, the content of component (D) in the composition is 1.5% by mass or more, the content of an oil-soluble UV absorber in the composition is less than 5% by mass, and the average particle size of emulsified particles in the composition is 0.1 ⁇ m or more and 0.8 ⁇ m or less.
• Example 1 is a scanning electron microscope (SEM) image of the cross section of an emulsified particle in the oil-in-water emulsion composition obtained in Example 1.
• UV scattering agents such as inorganic powders as UV protection agents have long been available in cream form using oily ingredients as the main base, but these have the problem of being sticky when applied to the skin and not feeling good to the touch.
• Some oil-in-water cosmetics have been formulated with inorganic powders to improve the feel when applied to the skin (Patent Document 2, etc.), but this has the problem of not providing sufficient UV protection. Therefore, the current mainstream technology is the use of inorganic powders in combination with oil-soluble UV absorbers, as in Patent Document 3.
• Patent Document 3 there is a demand for products that provide high UV protection even with reduced or no oil-soluble UV absorbers.
• the present invention relates to providing an oil-in-water emulsion composition that has excellent UV protection effects and a pleasant feel when used.
• oil-in-water emulsion compositions containing inorganic powder as a UV protection agent do not provide sufficient UV protection due to aggregation of the inorganic powder within the composition or after application of the composition to the skin. They have also found that this problem can be solved by adjusting the contents of the oil and inorganic powder that are liquid at 25°C within a specified range and the average particle size of the emulsified particles in the composition to a specified range in an oil-in-water emulsion composition that contains an ionic surfactant, a hydrophobic amphiphilic substance, an oil that is liquid at 25°C, an inorganic powder, and water, and in which the oil-soluble UV absorber is less than a specified amount.
• the oil-in-water emulsion composition of the present invention has excellent UV protection effects and a pleasant feel when used, making it useful as a variety of cosmetics, including sunscreen cosmetics.
• the oil-in-water emulsion composition of the present invention contains component (A): an ionic surfactant, component (B): a hydrophobic amphiphilic substance, component (C): an oil agent that is liquid at 25°C other than component (B), component (D): an inorganic powder, and component (E): water, wherein the content of component (C) in the composition is 17% by mass or more and 50% by mass or less, the content of component (D) in the composition is 1.5% by mass or more, the content of an oil-soluble ultraviolet absorber in the composition is less than 5% by mass, and the average particle size of emulsified particles in the composition is 0.1 ⁇ m or more and 0.8 ⁇ m or less.
• the composition of the present invention has an excellent ultraviolet protection effect and a good feeling when used.
• the composition of the present invention exhibits the above-mentioned effects is not clear, but is thought to be as follows.
• the composition of the present invention is an oil-in-water emulsion composition, which provides excellent feel when used. Furthermore, even if the content of the oil-soluble UV absorber is less than 5% by mass, the composition provides excellent UV protection effect.
• the inorganic powder (D) functions as an ultraviolet protection agent, and by ensuring that the content of component (D) in the composition is at least a predetermined amount, excellent ultraviolet protection effects can be obtained. However, if component (D) aggregates in the composition and after application of the composition to skin, the coating uniformity decreases, and the UV protection effect also tends to decrease.
• composition of the present invention (A) an ionic surfactant, (B) a hydrophobic amphiphilic substance, and (C) an oil agent other than component (B) that is liquid at 25°C are present together with component (D), and the composition is emulsified and dispersed in water to form a composition.
• component (D) emulsion particles
• ⁇ -gel particles emulsion particles having an ⁇ -gel structure in which components (C) and (D) are encapsulated in components (A) and (B).
• ⁇ -gel particles have excellent fastness and emulsion stability in water, they can suppress aggregation of component (D) in the composition and after application to a target object, and as a result, it is thought to obtain excellent UV protection effect. Furthermore, it is believed that component (D) encapsulated in component (A) and component (B) is dispersed in component (C). Therefore, when the content of component (C) in the composition is 17% by mass or more, component (D) is finely dispersed, which is believed to improve the UV protection effect. Furthermore, when the content of component (C) in the composition is 50% by mass or less, an oil-in-water composition can be stably obtained.
• the oil-in-water emulsion composition of the present invention contains an ionic surfactant as component (A). It is believed that the inclusion of component (A) in the composition of the present invention enables components (B) to (D) to be stably emulsified and dispersed in water, thereby forming the emulsified particles.
• component (A) preferably contains an anionic surfactant, and more preferably is an anionic surfactant.
• the anionic surfactant preferably contains a long-chain N-acyl glutamate from the viewpoint of emulsifying performance and forming the above-mentioned ⁇ -gel particles.
• the long-chain N-acyl glutamate is preferably an N-acyl glutamate having an acyl group having 12 to 24 carbon atoms, more preferably one or more selected from the group consisting of sodium N-lauroyl-L-glutamate, sodium N-stearoyl-L-glutamate, arginine N-stearoyl-L-glutamate, sodium N-myristoyl-L-glutamate, and sodium dilauroyl glutamate, even more preferably one or more selected from the group consisting of sodium N-stearoyl-L-glutamate and arginine N-stearoyl-L-glutamate, and even more preferably arginine N-stearoyl-L-glutamate.
• anionic surfactants other than long-chain N-acyl glutamates include polyoxyethylene alkyl ether sulfates, alkylbenzene sulfonates, alkyl or alkenyl sulfates, alkyl sulfonates, saturated or unsaturated fatty acid salts, alkyl or alkenyl ether carboxylates, ⁇ -sulfofatty acid salts, N-acylamino acid salts other than long-chain N-acyl glutamates, mono- or diester phosphate salts, sulfosuccinate ester salts, etc., and one or more of these can be used.
• the content of long-chain N-acyl glutamate in the anionic surfactant is preferably 50% by mass or more, more preferably 60% by mass or more, even more preferably 70% by mass or more, even more preferably 80% by mass or more, and even more preferably 90% by mass or more, and may be 100% by mass.
• the content of long-chain N-acyl glutamate refers to the content (% by mass) of long-chain N-acyl glutamic acid.
• Component (A) can be used alone or in combination of two or more types.
• the oil-in-water emulsion composition of the present invention contains a hydrophobic amphiphilic substance as component (B). It is believed that the composition of the present invention, which contains component (B), can form the emulsified particles in water together with components (A), (C), and (D), thereby obtaining an oil-in-water emulsion composition with excellent UV protection effect.
• hydrophobic amphiphilic substances include ceramides, alcohols having from 10 to 24 carbon atoms, linear saturated fatty acids having from 10 to 24 carbon atoms, fatty acid monoglycerin esters in which the acyl group has from 10 to 24 carbon atoms, monoalkyl glyceryl ethers in which the alkyl group has from 10 to 24 carbon atoms, fatty acid sorbitan esters in which the acyl group has from 10 to 24 carbon atoms, and fatty acid monosorbite esters in which the acyl group has from 10 to 24 carbon atoms.
• the number of carbon atoms in the acyl group and the number of carbon atoms in the alkyl group refer to the number of carbon atoms in one acyl group or alkyl group, and in the case of a two-chain compound, refer to the number of carbon atoms in each chain (the same applies hereinafter).
• the HLB hydrophilic-lipophilic balance
• ceramides As the ceramide, one or more types selected from the group consisting of natural ceramides and pseudo-ceramides can be used. From the viewpoint of improving the UV protection effect, the ceramides described in JP-A-2013-53146 are preferred. Specific examples of natural ceramides include ceramide Types 1 to 7, in which sphingosine, dihydrosphingosine, phytosphingosine, or sphingadienine is amidated (e.g., porcine and human ceramides shown in Figure 2 of J. Lipid Res., 24:759 (1983) and Figure 4 of J. Lipid. Res., 35:2069 (1994)).
• N-alkylated versions e.g., N-methylated versions
• these ceramides may be optically active natural (D(-) form), optically active non-natural (L(+) form), or mixtures thereof.
• D(-) form optically active natural
• L(+) form optically active non-natural
• CERAMIDE 1II all INCI, 8th Edition
• ceramides Commercially available natural ceramides include Ceramide I, Ceramide III, Ceramide IIIA, Ceramide IIIB, Ceramide IIIC, and Ceramide VI (all manufactured by Cosmopharm Co., Ltd.), Ceramide TIC-001 (manufactured by Takasago International Corporation), CERAMIDE II (manufactured by Quest International), DS-Ceramide VI, DS-CLA-Phytoceramide, C6-Phytoceramide, DS-ceramide Y3S (manufactured by DOOSAN Co., Ltd.), and CERAMIDE 2 (manufactured by Sederma Co., Ltd.).
• the pseudo-ceramide is preferably a pseudo-ceramide represented by the following general formula (1):
• R1 represents a hydrogen atom or a linear, branched, or cyclic, saturated or unsaturated hydrocarbon group having from 10 to 22 carbon atoms which may have a hydroxy group.
• X1 represents a hydrogen atom, an acetyl group, or a glyceryl group.
• R2 represents a linear, branched, or cyclic, saturated or unsaturated hydrocarbon group having from 5 to 22 carbon atoms which may have a hydroxy group or an amino group, or a hydrocarbon group having a linear or branched, saturated or unsaturated fatty acid having from 8 to 22 carbon atoms which may have a hydroxy group ester-bonded to the ⁇ -terminus.
• R3 represents a hydrogen atom or an alkyl group having a total of from 1 to 30 carbon atoms which may have a hydroxy group, a hydroxyalkoxy group, an alkoxy group, or an acetoxy group.
• pseudo-ceramides represented by the following formula are preferred from the perspective of improving UV protection effects.
• Alcohols having 10 to 24 carbon atoms include those having a linear or branched alkyl or alkenyl group having from 10 to 24 carbon atoms. From the viewpoint of improving the UV protection effect, the number of carbon atoms is preferably from 12 to 24, more preferably from 14 to 22, and even more preferably from 16 to 18. Examples of such alcohols include lauryl alcohol, myristyl alcohol, cetyl alcohol, stearyl alcohol, behenyl alcohol, and oleyl alcohol. Of these, those having a linear alkyl group are preferred, and one or more selected from the group consisting of cetyl alcohol and stearyl alcohol are more preferred, with cetyl alcohol being even more preferred.
• linear saturated fatty acids having from 10 to 24 carbon atoms examples include lauric acid, myristic acid, palmitic acid, stearic acid, behenic acid, etc.
• the number of carbon atoms of the linear saturated fatty acid is preferably from 12 to 24, more preferably from 14 to 22, and even more preferably from 16 to 18, and one or more selected from the group consisting of palmitic acid and stearic acid are preferred.
• a fatty acid monoglycerin ester having an acyl group containing from 10 to 24 carbon atoms refers to a monoester of a fatty acid containing from 10 to 24 carbon atoms and glycerin, and from the viewpoint of improving the UV protection effect, the number of carbon atoms of the fatty acid is preferably from 12 to 24, more preferably from 14 to 22, and even more preferably from 16 to 22.
• Examples of the monoglycerin ester include glycerin monolaurate, glycerin monomyristate, glycerin monopalmitate, glycerin monostearate, glycerin monobehenate, glycerin monooleate, and glycerin monoisostearate.
• glycerin monopalmitate glycerin monostearate
• glycerin monobehenate glycerin monooleate
• glycerin monoisostearate one or more selected from the group consisting of glycerin monopalmitate, glycerin monostearate, and glycerin monobehenate are preferred, with glycerin monobehenate being more preferred.
• Monoalkyl glyceryl ether having an alkyl group with 10 to 24 carbon atoms examples include monodecyl glyceryl ether, monolauryl glyceryl ether, monomyristyl glyceryl ether, monocetyl glyceryl ether, monostearyl glyceryl ether, monobehenyl glyceryl ether, etc.
• the number of carbon atoms in the alkyl group is preferably 12 to 24, more preferably 14 to 22, and even more preferably 16 to 22, and one or more types selected from the group consisting of monocetyl glyceryl ether, monostearyl glyceryl ether, and monobehenyl glyceryl ether are preferred.
• a sorbitan ester of a fatty acid having an acyl group containing from 10 to 24 carbon atoms refers to an ester of a fatty acid having from 10 to 24 carbon atoms and sorbitan, and from the viewpoint of improving the UV protection effect, a monoester or diester of the fatty acid is preferred, with a diester being more preferred.
• Fatty acids having from 10 to 24 carbon atoms are preferably linear saturated fatty acids, such as lauric acid, myristic acid, palmitic acid, stearic acid, and behenic acid.
• the number of carbon atoms in the fatty acid is preferably from 14 to 24, more preferably from 16 to 24, and even more preferably from 18 to 22.
• fatty acid sorbitan esters having an acyl group having from 10 to 24 carbon atoms include monoesters such as sorbitan monolaurate, sorbitan monomyristate, sorbitan monopalmitate, sorbitan monostearate, and sorbitan monobehenate; and diesters such as sorbitan dilaurate, sorbitan dimyristate, sorbitan dipalmitate, sorbitan distearate, and sorbitan dibehenate.
• one or more selected from the group consisting of sorbitan monostearate, sorbitan monobehenate, sorbitan dimyristate, sorbitan dipalmitate, sorbitan distearate, and sorbitan dibehenate are preferred, one or more selected from the group consisting of sorbitan dimyristate, sorbitan dipalmitate, sorbitan distearate, and sorbitan dibehenate are more preferred, and one or more selected from the group consisting of sorbitan dipalmitate and sorbitan distearate are even more preferred.
• a fatty acid monosorbite ester having an acyl group containing from 10 to 24 carbon atoms refers to a monoester of a fatty acid having from 10 to 24 carbon atoms and sorbitol.
• the fatty acid having from 10 to 24 carbon atoms is preferably a linear saturated fatty acid, such as lauric acid, myristic acid, palmitic acid, stearic acid, or behenic acid. From the viewpoint of improving the UV protection effect, the number of carbon atoms in the fatty acid is preferably from 16 to 24, and more preferably from 18 to 22.
• Component (B) may be used singly or in combination with other compounds. From the perspective of improving UV protection efficacy, component (B) preferably contains one or more compounds selected from the group consisting of alcohols having from 14 to 22 carbon atoms, fatty acid monoglycerin esters having from 14 to 22 carbon atoms in the acyl group, and fatty acid sorbitan esters having from 14 to 22 carbon atoms in the acyl group; more preferably contains alcohols having from 14 to 22 carbon atoms, fatty acid monoglycerin esters having from 14 to 22 carbon atoms in the acyl group, and fatty acid sorbitan esters having from 14 to 22 carbon atoms in the acyl group; even more preferably contains cetyl alcohol, glycerin monobehenate, and sorbitan distearate; and even more preferably component (B) consists of cetyl alcohol, glycerin monobehenate, and sorbitan distearate.
• Component (C) Oil that is liquid at 25°C>
• the oil-in-water emulsion composition of the present invention contains, as component (C), an oil other than component (B) that is liquid at 25°C (hereinafter simply referred to as "liquid oil”).
• liquid means that the oil has fluidity at 25°C and normal pressure, and is determined to be liquid in the liquid/solid determination test according to the American Society for Testing and Materials standard "ASTM D 4359-90: Standard Test Method for Determining Whether a Material is a Liquid or Solid.” It is believed that the inclusion of component (C) in the composition of the present invention allows component (D) to be finely dispersed, and further allows the formation of the emulsified particles in water together with components (A) and (B), thereby enabling an oil-in-water emulsion composition with excellent UV protection effect to be obtained.
• Component (C) is not particularly limited as long as it is a liquid oil used in ordinary cosmetics, and may be either a synthetic oil or a natural oil.
• synthetic oils include linear or branched hydrocarbon oils such as liquid paraffin, light liquid isoparaffin, squalane, and squalene; ester oils such as fatty acid monoesters composed of fatty acids and monohydric alcohols, such as cetyl 2-ethylhexanoate, isopropyl myristate, isopropyl palmitate, 2-ethylhexyl palmitate, 2-octyldodecyl myristate, and 2-ethylhexyl stearate; aromatic carboxylic acid monoesters composed of aromatic carboxylic acids and monohydric alcohols, such as alkyl benzoates (for example, alkyl benzoate (C12-15) "Finsorb TN" manufactured by Innospec Active Chemicals LLC); and polyhydric alcohol fatty acid esters composed of fatty
• Component (C) may also contain an oil-soluble UV absorber, but from the standpoint of ensuring flexibility in formulation, it is preferable that the content of the oil-soluble UV absorber is small.
• the oil-soluble ultraviolet absorber refers to an oil-soluble one among salicylic acid-based ultraviolet absorbers, para-aminobenzoic acid-based ultraviolet absorbers, cinnamic acid-based ultraviolet absorbers, benzophenone-based ultraviolet absorbers, triazine-based ultraviolet absorbers, benzoylmethane-based ultraviolet absorbers, and other organic ultraviolet absorbers.
• oil-soluble means water-insoluble, and specifically means that the solubility in 100 g of water at 25°C is 1 g or less.
• oil-soluble ultraviolet absorber examples include salicylic acid-based ultraviolet absorbers such as homomenthyl salicylate (homosalate, for example, “Parsol HMS” manufactured by DSM Co., Ltd.) and octyl salicylate (for example, “Parsol EHS” manufactured by DSM Co., Ltd.); para-aminobenzoic acid-based ultraviolet absorbers such as para-aminobenzoic acid, ethyl dihydroxypropyl para-aminobenzoate, glyceryl para-aminobenzoate, octyl dimethyl para-aminobenzoate, amyl para-dimethylaminobenzoate, and 2-ethylhexyl para-dimethylaminobenzoate; cinnamic acid-based ultraviolet absorbers such as 2-ethylhexyl paramethoxycinnamate (for example, "Uvinal MC80" manufactured by BASF SE), glyceryl di-
• Component (C) can be used singly or in combination with two or more types.
• component (C) is preferably one or more synthetic oils selected from the group consisting of straight-chain or branched-chain hydrocarbon oils, ester oils, and silicone oils, more preferably an ester oil, even more preferably one or more selected from the group consisting of fatty acid monoesters and aromatic carboxylic acid monoesters, even more preferably a fatty acid monoester, even more preferably one or more selected from the group consisting of cetyl 2-ethylhexanoate, isopropyl myristate, isopropyl palmitate, 2-ethylhexyl palmitate, 2-octyldodecyl myristate, and 2-ethylhexyl stearate, and even more preferably 2-ethylhexyl palmitate.
• composition of the present invention preferably further contains, as component (C'), an oil agent that is solid at 25°C.
• component (C') oil agent that is solid at 25°C.
• solid refers to a state in which there is no fluidity at 25°C and normal pressure, and which is determined to be solid in the liquid-solid determination test according to the American Society for Testing and Materials standard "ASTM D 4359-90: Standard Test Method for Determining Whether a Material is a Liquid or Solid.”
• component (C') include solid oils other than component (B) and oil-soluble UV absorbers, such as vegetable waxes such as candelilla wax, rice wax, sunflower wax, carnauba wax, and Japan wax; animal waxes such as beeswax and spermaceti; mineral waxes such as montan wax and ozokerite; petroleum waxes such as microcrystalline wax, paraffin, and ceresin; synthetic waxes such as hydrogenated castor oil, hydrogenated jojoba oil, 12-hydroxystearic acid, stearic acid amide, silicone wax, and polyethylene wax; hexadecyl myristate, hexadecyl palm
• component (C') preferably contains a petroleum-based wax, and more preferably contains one or more petroleum-based waxes selected from the group consisting of paraffin and ceresin.
• the oil-in-water emulsion composition of the present invention contains an inorganic powder as component (D).
• Component (D) functions as an ultraviolet protection agent, and by forming the emulsified particles in water together with components (A), (B), and (C), aggregation is suppressed, and an oil-in-water emulsion composition with excellent ultraviolet protection effect can be obtained.
• Component (D) is not limited as long as it is an ultraviolet scattering agent commonly used in cosmetics, and examples include metal oxide powders such as titanium oxide powder, zinc oxide powder, and cerium oxide powder; and metal powders such as aluminum powder. From the perspective of ultraviolet protection effect, component (D) preferably contains a metal oxide powder, more preferably contains one or more selected from the group consisting of titanium oxide powder and zinc oxide powder, and even more preferably contains titanium oxide powder.
• component (D) has been subjected to a conventionally known surface treatment.
• the surface treatment is preferably a hydrophobic surface treatment, and examples thereof include fluorine compound treatment (perfluoroalkyl phosphate ester treatment, perfluoroalkylsilane treatment, perfluoropolyether treatment, fluorosilicone treatment, fluorinated silicone resin treatment, etc.), silicone treatment (methylhydrogenpolysiloxane treatment, dimethylpolysiloxane treatment, gas-phase method tetramethyltetrahydrogencyclotetrasiloxane treatment, etc.), silicone resin treatment (trimethylsiloxysilicate treatment, etc.), pendant treatment (treatment of adding an alkyl chain or the like after gas-phase method silicone treatment, etc.), silane coupling agent treatment, titanium coupling agent treatment, silane treatment (alkylsilane treatment, alkylsilazane treatment,
• the surface treatment applied to component (D) may be a combination of two or more of the above surface treatments.
• the surface of titanium oxide powder may be coated with silane and a metal oxide such as alumina, and then surface-treated with an alkylsilane, a fatty acid, or the like, to produce a powder that can be used as component (D).
• component (D) is preferably titanium oxide powder whose surface has been treated with a metal soap such as a stearate, isostearate, or myristate.
• the shape of component (D) is not particularly limited, and examples thereof include spherical, flaky, plate-like, rod-like, spindle-like, needle-like, irregular, etc.
• the average particle size of component (D) is preferably 0.02 ⁇ m or more, more preferably 0.035 ⁇ m or more, and even more preferably 0.05 ⁇ m or more from the viewpoint of improving the UV protection effect, and is preferably 0.12 ⁇ m or less, more preferably 0.1 ⁇ m or less, and even more preferably 0.08 ⁇ m or less from the viewpoint of improving emulsion stability and storage stability and suppressing white residue upon application to the skin.
• the average particle size of component (D) can be determined in the same manner as for the average particle size of emulsified particles, as will be described in detail later.
• surface-treated zinc oxide powders include the FINEX series (manufactured by Sakai Chemical Industry Co., Ltd.), the MZ series, and the MZY series (all manufactured by Teika Corporation).
• commercially available surface-treated titanium oxide powders include the STR series (manufactured by Sakai Chemical Industry Co., Ltd.), the TTO-55 series, the TTO-51 series (all manufactured by Ishihara Sangyo Kaisha, Ltd.), the MT series, and the MTY series (all manufactured by Teika Corporation).
• Component (E) Water> As component (E), deionized water or distilled water is preferred, but tap water or groundwater sterilized with hypochlorous acid or the like may also be used as long as the stability of the composition of the present invention is not impaired.
• the composition of the present invention may contain cosmetic ingredients, medicinal ingredients, and ingredients commonly used in cosmetics, as appropriate, within the scope of the present invention.
• ingredients include surfactants other than component (A), powder dispersants, water-soluble polymers, thickeners, bactericides, moisturizers, humectants, colorants, preservatives, texture improvers, powders other than component (D), aqueous media other than component (E), fragrances, anti-inflammatory agents, whitening agents, antiperspirants, antioxidants, pH adjusters, etc.
• surfactants other than component (A) include nonionic surfactants such as polyoxyethylene sorbitan fatty acid esters and polyethylene alkyl ethers.
• the content of each component in the oil-in-water emulsion composition of the present invention is preferably as follows, from the viewpoint of providing an oil-in-water emulsion composition that has excellent UV protection effect and is pleasant to use.
• the content of component (A) in the composition is preferably 0.4% by mass or more, more preferably 1% by mass or more, and even more preferably 1.5% by mass or more, from the viewpoint of stably emulsifying and dispersing components (B) to (D) in water; and from the viewpoint of obtaining an excellent UV protection effect, it is preferably 10% by mass or less, more preferably 8% by mass or less, even more preferably 5% by mass or less, and still more preferably 3.5% by mass or less.
• the content of component (A) in the composition is preferably from 0.4% by mass to 10% by mass, more preferably from 1% by mass to 8% by mass, even more preferably from 1.5% by mass to 5% by mass, and still more preferably from 1.5% by mass to 3.5% by mass.
• component (A) is an anionic surfactant and is a salt of an acid compound
• the content of component (A) means the content as the acid compound.
• component (A) is a long-chain N-acyl glutamic acid salt
• the content of component (A) means the content (% by mass) of long-chain N-acyl glutamic acid.
• the content of component (B) in the composition is preferably 1% by mass or more, more preferably 2% by mass or more, even more preferably 3% by mass or more, and is preferably 12% by mass or less, more preferably 10% by mass or less, even more preferably 8% by mass or less, and still more preferably 5% by mass or less. Furthermore, from the viewpoint of improving storage stability and obtaining an excellent ultraviolet protection effect, the content of component (B) in the composition is preferably from 1% by mass to 12% by mass, more preferably from 2% by mass to 10% by mass, even more preferably from 3% by mass to 8% by mass, and still more preferably from 3% by mass to 5% by mass.
• the content of component (C) in the composition is 17% by mass or more, preferably 18% by mass or more, more preferably 19% by mass or more, and even more preferably 20% by mass or more, from the viewpoint of finely dispersing component (D) and obtaining an excellent UV protection effect, and from the viewpoint of stably obtaining an oil-in-water emulsion composition, it is 50% by mass or less, preferably 45% by mass or less, more preferably 40% by mass or less, even more preferably 35% by mass or less, still more preferably 30% by mass or less, and even more preferably 25% by mass or less.
• the content of component (C) in the composition is 17% by mass or more and 50% by mass or less, but from the viewpoint of finely dispersing component (D) and obtaining an excellent UV protection effect, it is preferably 18% by mass or more and 45% by mass or less, more preferably 19% by mass or more and 40% by mass or less, even more preferably 19% by mass or more and 35% by mass or less, still more preferably 20% by mass or more and 30% by mass or less, and even more preferably 20% by mass or more and 25% by mass or less.
• the content of component (C') in the composition is preferably 0.5% by mass or more, more preferably 1% by mass or more, and even more preferably 2% by mass or more, from the viewpoint of forming more robust ⁇ -gel particles in water, and is preferably 10% by mass or less, more preferably 8% by mass or less, and even more preferably 5% by mass or less, from the viewpoint of improving the feel during use.
• the content of component (C') in the composition is preferably from 0.5% by mass to 10% by mass, more preferably from 1% by mass to 8% by mass, and even more preferably from 2% by mass to 5% by mass, from the viewpoint of forming more robust ⁇ -gel particles in water.
• the content of component (D) in the composition is 1.5% by mass or more, preferably 2% by mass or more, more preferably 3% by mass or more, even more preferably 5% by mass or more, still more preferably 8% by mass or more, and still more preferably 10% by mass or more.
• the content is preferably 25% by mass or less, more preferably 20% by mass or less, and still more preferably 18% by mass or less.
• the content of component (D) in the composition is 1.5% by mass or more, preferably 1.5% by mass or more and 25% by mass or less, more preferably 3% by mass or more and 20% by mass or less, even more preferably 5% by mass or more and 20% by mass or less, still more preferably 8% by mass or more and 18% by mass or less, and even more preferably 10% by mass or more and 18% by mass or less.
• the content of component (E) in the composition is not particularly limited as long as it is within a range that allows stable formation of an oil-in-water emulsion composition containing components (A) to (D), but from the viewpoint of improving the usability, it is preferably 30% by mass or more, more preferably 40% by mass or more, and from the viewpoint of obtaining excellent UV protection effect, it is preferably 80% by mass or less, more preferably 70% by mass or less, even more preferably 60% by mass or less, and still more preferably 50% by mass or less.
• the content of component (E) in the composition is preferably 30% by mass or more and 80% by mass or less, more preferably 30% by mass or more and 70% by mass or less, even more preferably 40% by mass or more and 60% by mass or less, and still more preferably 40% by mass or more and 50% by mass or less.
• the total content of components (A) to (E) in the composition is preferably 50% by mass or more, more preferably 70% by mass or more, even more preferably 80% by mass or more, and even more preferably 85% by mass or more, and may be 100% by mass.
• the mass ratio of component (D) to component (C) in the composition [(D)/(C)] is preferably 0.01 or more, more preferably 0.1 or more, and even more preferably 0.3 or more, from the viewpoint of obtaining an excellent ultraviolet protection effect, and is preferably 1 or less, more preferably 0.9 or less, even more preferably 0.85 or less, and still more preferably 0.8 or less, from the viewpoint of improving the ultraviolet protection ability (ultraviolet protection efficiency) per amount of component (D).
• the mass ratio of component (D) to component (C) in the composition [(D)/(C)] is preferably 0.01 or more and 1 or less, more preferably 0.1 or more and 0.9 or less, even more preferably 0.3 or more and 0.85 or less, and still more preferably 0.3 or more and 0.8 or less.
• the UV protection efficiency can be specifically evaluated by the method described in the Examples.
• the content of the oil-soluble UV absorber in the composition of the present invention is less than 5% by mass, preferably 3% by mass or less, more preferably 1% by mass or less, even more preferably 0.1% by mass or less, and even more preferably 0% by mass.
• the emulsion particles in the composition of the present invention are preferably emulsion particles in which components (C) and (D) are encapsulated in components (A) and (B). More preferably, the emulsion particles are emulsion particles having an ⁇ -gel structure ( ⁇ -gel particles) in which components (C) and (D) are encapsulated in components (A) and (B). Because ⁇ -gel particles have excellent fastness and emulsion stability in water, they are thought to be able to suppress aggregation of component (D) in the composition and after application to the skin, resulting in excellent UV protection effects.
• emulsion particles in the composition are emulsion particles in which components (C) and (D) are encapsulated in components (A) and (B) can be confirmed by observing the cross section of the emulsion particles in the oil-in-water composition with a scanning electron microscope (SEM). Furthermore, whether the emulsion particles in the composition have an ⁇ -gel structure can be confirmed by X-ray diffraction (XRD). Specifically, particles that show at least one sharp diffraction peak at a Bragg angle of approximately 21 to 22° in wide-angle X-ray diffraction can be determined to have an ⁇ -gel structure.
• XRD X-ray diffraction
• Emulsion particles (preferably ⁇ -gel particles) in which components (C) and (D) are encapsulated in components (A) and (B) can be produced by the production method described below.
• the average particle size of the emulsified particles in the composition of the present invention is from 0.1 ⁇ m to 0.8 ⁇ m, preferably from 0.1 ⁇ m to 0.7 ⁇ m, and more preferably from 0.1 ⁇ m to 0.65 ⁇ m, from the viewpoint of obtaining an excellent ultraviolet protection effect.
• the average particle size refers to the volume median diameter (D50).
• the average particle size is a value measured at 25°C using a dynamic light scattering particle size distribution analyzer, and specifically, can be measured by the method described in the Examples.
• the method for producing the oil-in-water emulsion composition of the present invention preferably comprises the following steps I to III in this order:
• emulsion particles preferably ⁇ -gel particles, in which components (C) and (D) are encapsulated in components (A) and (B)
• Step I A step of dispersing component (D): inorganic powder in component (C): an oil agent other than component (B) that is liquid at 25°C to obtain a dispersion.
• Step II The dispersion obtained in Step I is mixed with component (A): an ionic surfactant and component (B): a hydrophobic amphiphilic substance, and the resulting mixture is mixed with component (E): water under heating to obtain an emulsion.
• Step III A step of cooling the emulsion obtained in Step II at a cooling rate of 1°C/min or more and 300°C/min or less.
• Step I an inorganic powder, component (D), is dispersed in a liquid oil, component (C), to obtain a dispersion.
• Step I allows component (D) to be finely dispersed in component (C).
• the apparatus used for dispersion in step I include high-pressure emulsifiers, ultrasonic emulsifiers, homogenizers, mills, dispersers, pitched paddles, homomixers, extruders, kneaders, and the like, which are commonly used when wet-dispersing a powder in a dispersion medium.
• component (C) from the viewpoint of finely dispersing component (D) in component (C), it is preferable to use a high-pressure emulsifier, homogenizer, or mill, and it is more preferable to use a high-pressure emulsifier. This is because when a high-pressure emulsifier is used, the average particle size of the resulting emulsion particles can be easily adjusted to a desired range by adjusting the pressure conditions.
• the pressure conditions can be set, for example, in the range of atmospheric pressure (0 MPa) to 300 MPa. From the perspective of adjusting the average particle size of the resulting emulsified particles to the desired range and enhancing the UV protection effect, the pressure conditions are preferably 0 MPa or higher, more preferably 30 MPa or higher, even more preferably 50 MPa or higher, and even more preferably 100 MPa or higher, and are preferably 300 MPa or lower, more preferably 250 MPa or lower.
• the dispersion in step I is preferably carried out under heating, although this varies depending on the type of component (C).
• the temperature during dispersion in step I is preferably 60°C or higher, more preferably 70°C or higher, from the viewpoint of finely dispersing component (D) in component (C), and is preferably 100°C or lower, more preferably 90°C or lower, from the viewpoints of productivity and preventing decomposition of the blended components.
• step II the dispersion obtained in step I is mixed with component (A) and component (B), and the resulting mixture is mixed with component (E) under heating to obtain an emulsion.
• the mixing temperature under heating varies depending on the types of component (B) and component (C), etc., but from the viewpoint of emulsion dispersibility and adjusting the average particle size of the resulting emulsion particles to a desired range, it is preferably 60°C or higher, more preferably 70°C or higher, and from the viewpoint of productivity and suppressing decomposition of the blended components, it is preferably 120°C or lower, more preferably 100°C or lower.
• step III the emulsion obtained in step II is cooled at a cooling rate of 1°C/min to 300°C/min (cooling step).
• step III emulsion particles having an ⁇ -gel structure in which components (C) and (D) are encapsulated in components (A) and (B) can be formed.
• component (C') when component (C') is used, component (C') is solidified in step III, resulting in the formation of more robust emulsion particles.
• the cooling rate is preferably 3° C./min or more, more preferably 5° C./min or more, even more preferably 10° C./min or more, still more preferably 30° C./min or more, still more preferably 50° C./min or more, still more preferably 100° C./min or more, still more preferably 150° C./min or more, still more preferably 180° C./min or more, and is preferably 250° C./min or less, more preferably 230° C./min or less.
• Step III a continuous rapid cooling method using a vibration-type agitation mixer, a scraped-surface heat exchanger (Onlator, manufactured by Sakura Seisakusho), a static mixer (manufactured by Noritake Company Limited), a general plate-type heat exchanger, a double-pipe heat exchanger, or the like, or a method of agitating and cooling in a general blending tank can be used.
• a method using a vibration-type agitation mixer is preferred.
• the vibration-type agitation mixer is a vibration-type agitation mixer that is provided with an agitator consisting of a drive shaft and an agitator blade attached to the drive shaft within a tubular casing, and the drive shaft is configured to vibrate in the axial direction, and it is preferable that the agitator blade has one or more openings and/or one or more notches.
• the cooling step it is preferable to supply the emulsion obtained in step II into the vibration-type stirring mixer and continuously cool it while stirring by vibrating the stirring blades, thereby obtaining an oil-in-water emulsion composition in which emulsified particles having an ⁇ -gel structure and a desired average particle size are dispersed in water.
• Examples of the high-pressure emulsifier used in Steps I and II and the vibration-type agitator/mixer used in the cooling step include those described in JP 2017-7969 A.
• the oil-in-water emulsion composition of the present invention has excellent UV protection effect and is therefore useful as an oil-in-water emulsion cosmetic (hereinafter also simply referred to as "cosmetics"), and is particularly useful as an UV protection cosmetic.
• cosmetics are preferably skin cosmetics that are applied to the skin, such as sunscreens, lotions, emulsions, creams, gels, serums, etc.
• the cosmetic preparations may be in the form of a sheet impregnated with or applied to a sheet-like substrate such as a woven fabric or nonwoven fabric.
• the cosmetic composition of the present invention can be used by applying it to the skin, preferably the skin excluding the scalp, and more preferably the face, trunk, or limbs.
• the present invention further discloses the following oil-in-water emulsion compositions, etc.
• Component (A) an ionic surfactant
• Component (B) hydrophobic amphiphilic substance
• Component (C) An oil other than component (B) that is liquid at 25°C
• Component (D) inorganic powder
• Component (E) water
• Contains The content of component (C) in the composition is 17% by mass or more and 50% by mass or less
• the content of component (D) in the composition is 1.5% by mass or more
• the content of the oil-soluble ultraviolet absorber in the composition is less than 5% by mass
• An oil-in-water emulsion composition wherein the average particle size of the emulsion particles in the composition is 0.1 ⁇ m or more and 0.8 ⁇ m or less.
• ⁇ 2> The oil-in-water emulsion composition according to ⁇ 1>, wherein the component (A) is an anionic surfactant.
• ⁇ 4> ⁇ 4> The oil-in-water emulsion composition according to any one of ⁇ 1> to ⁇ 3>, wherein the emulsion particles are emulsion particles in which component (C) and component (D) are encapsulated in component (A) and component (B).
• the oil-in-water emulsion composition according to any one of ⁇ 1> to ⁇ 4>, further comprising a component (C'): an oil agent that is solid at 25°C. ⁇ 6> ⁇ 5> The oil-in-water emulsion composition according to ⁇ 5>, wherein the content of the component (C') in the composition is 0.5% by mass or more and 10% by mass or less.
• ⁇ 7> ⁇ 6> The oil-in-water emulsion composition according to any one of ⁇ 1> to ⁇ 6>, wherein the component (D) includes at least one selected from the group consisting of titanium oxide powder and zinc oxide powder.
• ⁇ 8> ⁇ 8> The oil-in-water emulsion composition according to any one of ⁇ 1> to ⁇ 7>, wherein the content of the component (A) in the composition is 0.4% by mass or more and 10% by mass or less.
• ⁇ 9> ⁇ 9> The oil-in-water emulsion composition according to any one of ⁇ 1> to ⁇ 8>, wherein the content of the component (B) in the composition is 1% by mass or more and 12% by mass or less.
• ⁇ 10> ⁇ 9> The oil-in-water emulsion composition according to any one of ⁇ 1> to ⁇ 9>, wherein the content of the component (D) in the composition is 1.5% by mass or more and 25% by mass or less.
• ⁇ 11> ⁇ 9> The oil-in-water emulsion composition according to any one of ⁇ 1> to ⁇ 9>, wherein the content of the component (D) in the composition is 10% by mass or more and 18% by mass or less.
• ⁇ 12> The oil-in-water emulsion composition according to any one of ⁇ 1> to ⁇ 11>, which is a cosmetic.
• the refractive index of the sample was 1.446 for ethylhexyl palmitate, and the refractive index of the dispersion medium was 1.333 for water.
• Example 1 (Production and Evaluation of Oil-in-Water Emulsion Composition (UV Protection Cosmetic)) ⁇ Step I> 2-ethylhexyl palmitate (component (C)), titanium oxide (component (D)), and polyhydroxystearic acid (listed in Table 1) were mixed in a disper under heating at 85°C, and then a high-pressure emulsifier (Starburst Mini HJP-25001, manufactured by Sugino Machine Ltd.) was used to obtain a dispersion in which component (D) was finely dispersed in component (C). The number of passes through the high-pressure emulsifier (number of passes) was 1, and the high-pressure emulsification pressure was 200 MPa.
• a high-pressure emulsifier Starburst Mini HJP-25001, manufactured by Sugino Machine Ltd.
• Step II> the dispersion obtained in step I, component (A), component (B), component (C′), glycerin, 1,3-propanediol, and dextrin palmitate shown in Table 1 were melted and mixed with a paddle under heating at 85°C to prepare mixture A.
• water (component (E)), L-arginine, and phenoxyethanol shown in Table 1 were mixed under heating at 85°C to prepare mixture B.
• Mixture B was added to Mixture A and dispersed using a homomixer. The resulting mixture was emulsified using the high-pressure emulsifier to obtain an emulsion.
• Step III The emulsion obtained in step II was fed to a vibration-type agitation mixer ("Vibromixer" manufactured by Reika Kogyo Co., Ltd.) with a transition time of 10 seconds while maintained at 85°C. The emulsion was continuously cooled to 40°C or below at a cooling rate of 210°C/min while stirring by vertically vibrating the agitator within the mixer, yielding an oil-in-water emulsion composition (UV protective cosmetic).
• Vibromixer manufactured by Reika Kogyo Co., Ltd.
• the emulsion flow rate was 4 g/sec, and the total flow rate of cooling water circulating through the cooling jacket was 8 g/sec. Cooling was achieved with cooling water at a total flow rate twice the emulsion flow rate.
• the vibration frequency of the vibration-type agitation mixer was 20 Hz.
• the obtained cosmetic preparations were evaluated using the above-mentioned methods. The results are shown in Table 1.
• the blending amounts shown in Table 1 are the amount of active ingredient (% by mass) of each ingredient.
• Titanium oxide MT-10EX (manufactured by Teika Co., Ltd.), treated with alkali metal isostearate, average particle size: 0.060 ⁇ m *9 86% glycerin (Kao Corporation) *10 1,3-propanediol (manufactured by Glory) *11 Palmitic acid dextrin: Leopearl KL2 (manufactured by Chiba Flour Milling Co., Ltd.) *12 L-arginine (Ajinomoto Co., Inc.) *13 Phenoxyethanol: Hysolv EPH (manufactured by Toho Chemical Industry Co., Ltd.) *14 Polyhydroxystearic acid: contained in titanium oxide MT-10EX dispersion liquid "FLT-12" (manufactured by Teika Co., Ltd.).
• the UV protective cosmetic comprising the oil-in-water emulsion composition of the present invention has a high UV protective effect even when the content of the oil-soluble UV absorber is less than 5% by mass.
• the cosmetics of Comparative Example 1 in which the average particle size of the emulsified particles exceeded 0.8 ⁇ m, Comparative Example 2, in which the content of component (C) was less than 17% by mass, and Comparative Example 3, in which the content of component (D) was less than 1.5% by mass, all had low UV protection effects.
• Figure 1 is a scanning electron microscope (SEM) image of the cross section of an emulsion particle in the oil-in-water emulsion composition obtained in Example 1.
• SEM scanning electron microscope
• the SEM photography was performed using the following method. Specifically, a sample (oil-in-water emulsion composition) was drawn into a glass capillary, rapidly frozen, and then cut so that the cross section could be observed. The sample was then sublimated at -90°C for 20 minutes to prepare a specimen for observation. The specimen for observation was observed and photographed using a cryo-SEM at an accelerating voltage of 1.0 kV and a magnification of 30,000x.
• Comparative Example 4 A comparison was made in which the ionic surfactant was replaced with a nonionic surfactant. That is, a composition was produced in the same manner as in Example 1, except that the ingredients of the cosmetic preparation in Example 1 were changed as shown in Table 2. However, the resulting composition was a water-in-oil type, and an oil-in-water emulsion composition could not be obtained. Furthermore, when the appearance of the resulting water-in-oil emulsion composition was visually observed, the formation of emulsified particles was not confirmed, and the formation of aggregates was observed.
• the oil-in-water emulsion composition of the present invention has excellent UV protection effects and a pleasant feel when used, making it useful as a variety of cosmetics, including sunscreen cosmetics.
• ⁇ -gel which is the outer shell of an emulsified particle composed of component (A) and component (B), 2:1 ⁇ -gel.
• Component (C) encapsulated in the ⁇ -gel.

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