Oil-in-water sunscreen cosmetics

Abstract

The objective is to provide an oil-in-water type sunscreen cosmetic that offers sufficient UV protection, good dispersibility of UV scattering agents and emulsification stability under high-temperature conditions, a refreshing feel, and good skin compatibility upon application. [Solution] The oil-in-water sunscreen cosmetic contains (A) an ultraviolet scattering agent, (B) a plate-like powder different from (A) the ultraviolet scattering agent, (C) an oil with a melting point of 35°C or higher and 65°C or lower, and (D) a polyoxyethylene addition type nonionic surfactant.

Description

Technical Field

[0001] The present invention relates to an oil-in-water type sunscreen cosmetic containing an ultraviolet scattering agent.

Background Art

[0002] In recent years, as the adverse effects of ultraviolet rays on the skin have become generally recognized, sunscreen cosmetics have come to be used daily throughout the year. Against this backdrop, oil-in-water type sunscreen cosmetics, which can be used daily without resistance and are characterized by a fresh feel, are popular. In sunscreen cosmetics, an ultraviolet protection agent is blended to enhance the SPF (Sun Protection Factor) as an ultraviolet protection effect. Examples of ultraviolet protection agents include inorganic metal oxides that scatter ultraviolet rays, such as titanium oxide and zinc oxide, and organic ultraviolet absorbers that absorb ultraviolet rays, such as oxybenzone and octinoxate. Many of these ultraviolet protection agents are hydrophobic (lipophilic), and when they are highly blended to enhance the ultraviolet protection effect, the blending amount of the oily component increases, so that in oil-in-water emulsification, the ratio of the internal phase becomes high, and there are problems with emulsion stability.

[0003] Therefore, a method of adding an ultraviolet protection agent not only to the oil phase side but also to the water phase side in an oil-in-water emulsified sunscreen cosmetic has been reported. For example, in Patent Document 1 (Japanese Unexamined Patent Application Publication No. 2017-114900), an emulsified cosmetic has been proposed that contains an ultraviolet scattering agent in the oil phase and the water phase in an ultraviolet scattering agent that may be surface-treated, a solid ultraviolet absorber, and a specific powder, has a high ultraviolet protection effect and water resistance, is moderately stretchy, has good transparency, and has high stability.

[0004] On the other hand, improvements in emulsion stability have also been reported in oil-in-water sunscreen cosmetics containing a hydrophobic UV-blocking agent in the oil phase. Patent Document 2 (JP 2022-096101 A) proposes an oil-in-water emulsion cosmetic containing a hydrophobic UV-scattering agent, a nonionic surfactant with an HLB of 14 or higher, an oil component, and a dispersant, and proposes a sunscreen cosmetic with good dispersibility of the UV-scattering agent in the oil phase, good emulsion stability, and high washability. Furthermore, Patent Document 3 (JP 2024-089745 A) proposes an oil-in-water emulsion composition containing an inorganic powder with a specific surface treatment, a paste-like oil, and an anionic surfactant, which has good emulsion stability and high-temperature stability and less squeaky feeling. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2017-114900 [Patent Document 2] Japanese Patent Publication No. 2022-096101 [Patent Document 3] Japanese Patent Publication No. 2024-089745 [Overview of the project] [Problems that the invention aims to solve]

[0006] However, the oil-in-water emulsion sunscreen cosmetic described in Patent Document 1 had a problem with dispersibility because the preliminary dispersion treatment required several hours to improve the dispersibility of the UV scattering agent, which is important for enhancing the UV protection effect. In addition, although it had good spreadability and softness, there were still issues with improving the freshness and long-term emulsion stability at high temperatures. Furthermore, by incorporating the UV scattering agent into the aqueous phase, which is the outer phase, a new problem was discovered: when applied to the skin, powders are more easily exposed on the skin due to the evaporation of volatile components, and aggregates of the emulsion composition are more likely to form on the skin.

[0007] While the oil-in-water emulsion sunscreen cosmetics described in Patent Documents 2 and 3 exhibited excellent dispersion stability, emulsification stability, and high-temperature stability, the inclusion of numerous UV-blocking agents in the oil phase reduced their freshness, leaving challenges in improving the oily feel after application.

[0008] In other words, a water-based oil-type sunscreen cosmetic that incorporates UV scattering agents in both the oil and aqueous phases, improves the dispersibility of the UV scattering agents and the emulsification stability under high-temperature conditions, while also providing a refreshing feel and good absorption into the skin upon application, has yet to be developed.

[0009] The object of the present invention is to provide an oil-in-water type sunscreen cosmetic that has sufficient UV protection effect, good dispersibility of UV scattering agents and emulsification stability under high temperature conditions, a refreshing feel, and good skin compatibility upon application. [Means for solving the problem]

[0010] The present invention relates to (A) an ultraviolet scattering agent, (B)(A) A plate-shaped powder different from the ultraviolet scattering agent, (C) Oils with a melting point of 35°C or higher and 65°C or lower, (D) The present invention relates to an oil-in-water type sunscreen cosmetic characterized by containing a polyoxyethylene-additive type nonionic surfactant. [Effects of the Invention]

[0011] According to the present invention, it is possible to provide an oil-in-water type sunscreen cosmetic that has sufficient UV protection, good dispersibility of UV scattering agents and emulsification stability under high temperature conditions, a refreshing feel, and good skin compatibility upon application. [Modes for carrying out the invention]

[0012] (A: UV scattering agent) An ultraviolet scattering agent refers to a substance that can scatter ultraviolet rays and protect the skin from ultraviolet radiation. Examples of ultraviolet scattering agent materials that can be used in this invention include titanium dioxide, zinc oxide, iron oxide, zirconium oxide, and aluminum oxide. Furthermore, ultraviolet scattering agents can be made by micronizing or compounding these materials.

[0013] The ultraviolet scattering agent preferably contains one or more selected from titanium dioxide and zinc oxide. The titanium dioxide and zinc oxide used as ultraviolet scattering agents may be those commonly used in cosmetics. Preferably, it may contain those with better dispersibility, for example, those whose surfaces have been surface-treated by known methods as needed, specifically hydrophobic treatment or hydrophilic treatment.

[0014] Surface treatment methods include silicone treatment such as methylhydrogenpolysiloxane and methylpolysiloxane; fluorine treatment with perfluoroalkyl phosphate esters, perfluoroalcohols, etc.; amino acid treatment with N-acyl glutamic acid, etc.; alkylalkoxysilane treatment with octyltriethoxysilane, octyltrimethoxysilane, etc.; silica treatment with silica, hydrated silica, etc.; inorganic oxide treatment with hydrated alumina, zirconia, etc.; and other treatments such as sodium alginate treatment, lecithin treatment, metal soap treatment, fatty acid treatment, and alkyl phosphate ester treatment.

[0015] The titanium dioxide and zinc oxide used in the present invention are preferably micronized to a particle size of 8 to 80 nm, and more preferably 8 to 50 nm. Furthermore, from the viewpoint of enhancing the effects of the present invention, it is preferable to use a hydrophilically treated ultraviolet scattering agent. The hydrophilizing treatment is not particularly limited as long as the effects of the present invention can be obtained, and any treatment that improves the affinity between the inorganic powder and water is acceptable. Specific examples of these hydrophilizing treatments include coating part or all of the surface of the inorganic powder with one or more surface treatment agents selected from silica, hydrated silica, hydrated alumina, zirconia, sodium alginate, hydrogen dimethicone, etc. Among these, hydrophilizing treatment using silica, hydrated silica, hydrated alumina, or sodium alginate is preferred because it results in better dispersibility. The hydrophilizing treatment may also be carried out to form a multilayer.

[0016] Examples of hydrophilically treated ultraviolet scattering agents include MT-05 (manufactured by Teika Co., Ltd., primary particle size 10 nm), MT-100AQ (manufactured by Teika Co., Ltd., primary particle size 15 nm), MT-100WP (manufactured by Teika Co., Ltd., primary particle size 15 nm); STR-100W (manufactured by Sakai Chemical Industry Co., Ltd., primary particle size 15 nm), STR-100W-LP (manufactured by Sakai Chemical Industry Co., Ltd., primary particle size 15 nm), STR-100W-OTS (manufactured by Sakai Chemical Industry Co., Ltd., primary particle size 15 nm), and FINE. Commercially available products such as X-52W-LP2 (manufactured by Sakai Chemical Industry Co., Ltd., primary particle size 25 nm), FINEX-33W (manufactured by Sakai Chemical Industry Co., Ltd., primary particle size 35 nm), FINEX-33W-LP2 (manufactured by Sakai Chemical Industry Co., Ltd., primary particle size 35 nm); ST-457ECS (manufactured by Titanium Industry Co., Ltd., primary particle size 10 nm), ST-455WS (manufactured by Titanium Industry Co., Ltd., primary particle size 15 nm), and ST-410WB (manufactured by Titanium Industry Co., Ltd., primary particle size 20 nm) can be used.

[0017] When the total amount of the oil-in-water type sunscreen cosmetic of the present invention is 100% by mass, the content of (A) ultraviolet scattering agent is preferably 0.5 to 20% by mass. By setting the content of (A) ultraviolet scattering agent to 0.5% by mass or more, the ultraviolet protection effect is further improved. From this viewpoint, it is even more preferable that the content of (A) ultraviolet scattering agent be 1% by mass or more. Furthermore, by setting the content of (A) ultraviolet scattering agent to 20% by mass or less, the refreshing feel is improved and the skin absorption during application is improved. From this viewpoint, it is preferable that the content of (A) ultraviolet scattering agent be 15% by mass or less, and even more preferable that it be 10% by mass or less.

[0018] ((B): Plate-shaped powder) Plate-like particles are particles having at least one pair of main surfaces and a side surface between the main surfaces, and having a ratio of the minor axis to the particle thickness (minor axis / thickness) of 2 or more. The thickness of the particle is the distance between the pair of main surfaces. The ratio of the minor axis to the particle thickness (minor axis / thickness) is preferably 3 or more, and more preferably 5 or more. Furthermore, the shape of the main surfaces of the plate-like particles is not particularly limited, and the main surfaces do not need to be perfectly flat; they may be curved.

[0019] The raw materials for the plate-shaped powder are not particularly limited. However, the plate-shaped powder (B) used in this invention shall be the same as the ultraviolet scattering agent (A). For example, the raw materials for the plate-shaped powder include clay minerals such as talc, mica, sericite, kaolin, clay, and bentonite; metal oxides such as zirconium oxide, magnesium oxide, and aluminum oxide; inorganic salts such as calcium sulfate, barium sulfate, magnesium sulfate, calcium carbonate, and magnesium carbonate; and other materials such as boron nitride, synthetic fluorophlogopite, silicic acid, anhydrous silicic acid, titanium mica, bismuth oxychloride, and hydroxyapatite. Among these, the plate-shaped powder is preferably clay minerals such as talc, mica, sericite, clay, and bentonite, with talc being more preferable, from the viewpoint of improving the dispersibility of the ultraviolet scattering agent (A), the refreshing feel of use, and the skin compatibility.

[0020] The average particle size of the plate-shaped powder is preferably 10 μm or more. When the average particle size of the plate-shaped powder is 10 μm or more, the dispersibility of the ultraviolet scattering agent is further improved. Further, the average particle size of the plate-shaped powder is preferably 30 μm or less, whereby the emulsion stability under high-temperature conditions and the skin feel during application are further improved. From this viewpoint, the average particle size of the plate-shaped powder is more preferably 20 μm or less.

[0021] The average particle size of the plate-shaped powder is measured on a volume basis by a particle size distribution measuring instrument using the laser diffraction / scattering method. Specifically, using ethanol as a dispersion medium, it is measured with a laser diffraction / scattering type particle size distribution analyzer, and the 50% median diameter is taken as the average particle size.

[0022] Further, the bulk density (g / ml) of the plate-shaped powder is preferably 0.1 to 0.5. When the bulk density (g / ml) of the plate-shaped powder is within the above range, it is easy to obtain the effect of improving the dispersibility of the ultraviolet scattering agent and the improvement of the feeling of use. Furthermore, the bulk density (g / ml) of the plate-shaped powder is more preferably 0.2 or more, and more preferably 0.4 or less.

[0023] In this embodiment, the bulk density (g / ml) of the powder is the ratio of the mass of the powder sample to the volume of the powder including the factor of the interparticle void volume (mass of the powder sample (g) / volume of the powder including the factor of the interparticle void volume (ml)). The bulk density (g / ml) of the powder can be determined by using a measuring container.

[0024] Commercially available talc products such as Talc JA-80R (manufactured by Asada Flour Milling Co., Ltd., volume average particle size 12 μm, bulk density 0.3), Talc C-R1 (manufactured by Nippon Talc Co., Ltd., volume average particle size 11 μm, bulk density 0.27), Talc GAHC (manufactured by Nippon Talc Co., Ltd., volume average particle size 16 μm, bulk density 0.3), Rose Talc (manufactured by Nippon Talc Co., Ltd., volume average particle size 17 μm, bulk density 0.4), Crown Talc JS (manufactured by Matsumura Sangyo Co., Ltd., volume average particle size 14 μm, bulk density 0.34), Crown Talc PPP (manufactured by Matsumura Sangyo Co., Ltd., volume average particle size 19 μm, bulk density 0.41), and High Filler #13 (manufactured by Matsumura Sangyo Co., Ltd., volume average particle size 16 μm, bulk density 0.3) can be used.

[0025] When the total amount of the oil-in-water type sunscreen cosmetic of the present invention is 100% by mass, the content of (B) ultraviolet scattering agent is preferably 0.5 to 10% by mass. By setting the content of (B) ultraviolet scattering agent to 0.5% by mass or more, the dispersibility of the ultraviolet scattering agent is further improved, and the skin absorption upon application is further improved. From this viewpoint, it is preferable that the content of (B) ultraviolet scattering agent be 1% by mass or more. Furthermore, by setting the content of (B) ultraviolet scattering agent to 10% by mass or less, the emulsification stability under high temperature conditions is further improved, and the skin absorption upon application is further improved. From this viewpoint, it is even more preferable that the content of (B) ultraviolet scattering agent be 8% by mass or less, and particularly preferable that it be 5% by mass or less.

[0026] In the present invention, (B) plate-shaped powder is added to the outer phase (aqueous phase) together with (A) ultraviolet scattering agent.

[0027] Furthermore, from the viewpoint of enhancing the effects of the present invention, the ratio (A) / (B) of the mass of (A) the ultraviolet scattering agent to the mass of (B) the plate-like powder is preferably in the range of 0.5 to 15, and more preferably in the range of 1 to 10. By setting the ratio (A) / (B) of the mass of (A) the ultraviolet scattering agent to the mass of (B) the plate-like powder to 0.5 or more, powderiness is suppressed and skin compatibility during application is improved. Also, by setting (A) / (B) to 15 or less, dispersibility during application is further improved.

[0028] ((C) Oils with a melting point of 35°C or higher and 60°C or lower) The (C) oils used in the present invention, which have a melting point of 35°C or higher and 60°C or lower, are not particularly limited as long as they are used in cosmetics. Specifically, examples include hydrocarbons such as petrolatum, oils and fats such as coconut oil, ester oils such as pentaerythrityl fatty acids, silicone oils such as high-molecular-weight dimethylpolysiloxane, lanolin and lanolin derivatives, etc., which are commonly used in cosmetics regardless of their origin, such as animal oils, vegetable oils, or synthetic oils, and one or more of these can be used. Among these, ester oils are preferred, and among them, diesters of dimer acid and / or dimer ol, phytosterol fatty acid esters, and dipentaerythrityl fatty acid esters are preferred. From the viewpoint of reducing powderiness and enhancing moisturizing effect, dipentaerythrityl fatty acid esters are even more preferred, and dipentaerythrityl hexahydroxystearate is particularly preferred.

[0029] Diesters of dimer acids and / or dimer ols refer to esters of dimer acids obtained by dimerizing mono- or di-unsaturated fatty acids and then hydrogenating them as needed, with various alcohols, as well as esters of dimer ols obtained by reducing dimer acids with various fatty acids, and esters of dimer acids and dimer ols. Examples include di(phytosteryl / isostearyl / cetyl / stearyl / behenyl) dimer dilinoleate, di(isostearyl / phytosteryl) dimer dilinoleate, dilinoleyl diisostearate, and dimer dilinoleyl bis(behenyl / isostearyl / phytosteryl) dimer dilinoleate. These compounds are commercially available from Nippon Seika Co., Ltd. as follows: di(phytosteryl / isostearyl / cetyl / stearyl / behenyl) dimer dilinoleate as "Plandool(registered trademark)-H", di(isostearyl / phytosteryl) dimer dilinoleate as "LUSPLAN(registered trademark)PI-DA", dilinoleyl dimer dilinoleate as "LUSPLAN(registered trademark)DD-DA5" and "LUSPLAN(registered trademark)DD-DA7", dimer dilinoleyl diisostearate as "LUSPLAN(registered trademark)DD-IS", and dimer dilinoleyl bis(behenyl / isostearyl / phytosteryl) dimer dilinoleate as "Plandool(registered trademark)-G", etc. These can be purchased and used.

[0030] Examples of phytosterol fatty acid esters include macadamia nut oil fatty acid phytosteryl, lanolin fatty acid phytosteryl, stearate phytosteryl, isostearate phytosteryl, hydroxystearate phytosteryl, oleate phytosteryl, dihydrophytosteryl oleate, ricinoleate phytosteryl, nonanoate phytosteryl, rice bran oil fatty acid phytosteryl, palmitate phytosteryl, 2-ethylhexanoate phytosteryl, caprate phytosteryl, laurate phytosteryl, and butyrate phytosteryl. Examples of commercially available phytosterol esters include "Plandool-MAS" (macadamia nut fatty acid phytosteryl), "Plandool-ISS" (isostearate phytosteryl), "Plandool-SUN" (oleate phytosteryl), "Plandool-LG1", "Plandool-LG3", "Plandool-LG4" (lauroyl glutamate di(octyldodecyl / phytosteryl / behenyl)), and "Plandool-LG2" (lauroyl Examples include: Di(phytosteryl / octyldodecyl) glutamate (manufactured by Nippon Seika Co., Ltd.); "Eldew PS-203" (Di(phytosteryl / octyldodecyl) lauroyl glutamate), "Eldew PS-304", "Eldew PS-306" (Di(octyldodecyl / phytosteryl / behenyl) lauroyl glutamate), "Eldew APS-307" (Phytosteryl / decyltetradecyl myristoylmethyl-β-alanine) (manufactured by Ajinomoto Co., Inc.); "Saracos FH" (Phytosteryl hydroxystearate), "Saracos PO(T)" (Phytosteryl oleate) (manufactured by Nisshin Oillio Group Ltd.).

[0031] Dipentaerythrityl fatty acid esters are a type of ester oil that has an ester bond, formed by the condensation of multiple different fatty acids (e.g., hydroxystearic acid, a combination of stearic acid and rosinic acid, or a combination of hydroxystearic acid and isostearic acid) with the polyhydric alcohol dipentaerythritol. Specific examples of dipentaerythrityl fatty acid esters include hexa(hydroxystearic acid / stearic acid / rosinic acid)dipentaerythrityl (e.g., "Cosmoll 168ARV" (product name: Nisshin Oillio Co., Ltd.)), tetra(hydroxystearic acid / isostearic acid)dipentaerythrityl (e.g., "Cosmoll 168EV" (product name: manufactured by Nisshin Oillio Co., Ltd.)), and hexahydroxystearate dipentaerythrityl (e.g., "Cosmoll 168M" (product name: manufactured by Nisshin Oillio Co., Ltd.)).

[0032] In this invention, the melting point of the oil is measured by Method 3 of the general test methods described in the Cosmetic Raw Materials Standards. Specifically, the sample is gradually heated to 90-92°C while stirring to melt it, then the heating is stopped and the sample is allowed to cool to a temperature 8-10°C above its melting point. Next, the thermometer (a petrolatum melting point thermometer specified in Japanese Industrial Standard B7410) is cooled to 5°C, the moisture is wiped off with filter paper, half of the mercury bulb is inserted into the sample, and then immediately removed. The sample is kept vertical and allowed to cool. When the attached sample becomes cloudy, it is immersed in water at a temperature of 16°C or lower for 5 minutes. Next, the thermometer is inserted into the test tube and fixed with a cork so that the distance between the lower end of the thermometer and the bottom of the test tube is 15 mm. The test tube is placed in a 500 mL beaker containing water at approximately 16°C, with the distance between the bottom of the test tube and the bottom of the beaker being 15 mm. The water is heated at a rate of 2°C per minute until the water temperature reaches 30°C. Then, heating is continued at a rate of 1°C per minute, and the temperature is measured when a drop of the sample leaves the thermometer. This test is performed three times. If the difference in measurements is less than 1°C, the average value is taken. If the difference is 1°C or greater, five measurements are taken and the average value is taken as the melting point. If the average melting point obtained from the measurements is a decimal value, it is rounded to the nearest integer.

[0033] The melting point of the (C) oil agent used in the present invention, which has a melting point of 35°C or higher and 60°C or lower, is preferably 35°C or higher and 50°C or lower, and more preferably 35°C or higher and 45°C or lower. Furthermore, the content of the (C) oil agent used in the present invention, which has a melting point of 35°C or higher and 60°C or lower, is preferably 0.05 to 5% by mass when the total amount of the oil-in-water type sunscreen cosmetic is 100% by mass, from the viewpoint of enhancing the ultraviolet protection effect. By setting the content of the (C) oil agent to 0.05% by mass or higher, the emulsification stability under high temperature conditions and skin compatibility upon application are further improved. From this viewpoint, the content of the (C) oil agent is more preferably 0.1% by mass or higher, and particularly preferably 0.3% by mass or higher. Furthermore, by setting the concentration of the (C) oil agent to 5% by mass or lower, the refreshing feel is further improved. From this viewpoint, the concentration of the (C) oil agent is preferably 4% by mass or lower, and more preferably 1% by mass or lower.

[0034] (D) Polyoxyethylene-added nonionic surfactant In the present invention, the (D) polyoxyethylene-added nonionic surfactant used preferably includes a polyoxyethylene-added nonionic surfactant with an HLB of 15 or higher, from the viewpoint of enhancing the effects of the invention.

[0035] Here, HLB (Hydrophilic-Lypophilic Balance) represents the molecular weight of the hydrophilic group portion of the total molecular weight of the surfactant, and for nonionic surfactants, it is determined by Griffin's formula.

[0036] The HLB of a mixed surfactant composed of two or more nonionic surfactants is determined as follows: The HLB of the mixed surfactant is obtained by averaging the HLB values ​​of each nonionic surfactant based on their respective blending ratios. Mixed HLB=Σ(HLBx×Wx) / ΣWx HLBx indicates the HLB value of the nonionic surfactant X. Wx represents the weight (g) of the nonionic surfactant X having an HLBx value.

[0037] Polyoxyethylene-additive nonionic surfactants with an HLB value of 15 or higher are nonionic surfactants having two or more oxyethylene molecules in their molecule, and examples include polyoxyethylene hydrogenated castor oil, polyoxyethylene alkyl ethers, fatty acid polyoxyethylene sorbitan, fatty acid polyoxyethylene glyceryl, polyethylene glycol fatty acid esters, and polyether-modified silicones.

[0038] Specifically, PEG-60 hydrogenated castor oil (HLB: 15), PEG-80 hydrogenated castor oil (HLB: 15), PEG-100 hydrogenated castor oil (HLB: 16.5), PEG-80 sorbitan laurate (HLB: 19), PEG-15 glyceryl oleate (HLB: 14.5), PEG-20 sorbitan cocoate (HLB: 16.9), PEG-30 sorbitan cocoate (HLB: 17.4), PEG-78 sorbitan cocoate (HLB: 18.9), PEG-12 glyceryl laurate (HLB: 15) PEG-20 glyceryl laurate (HLB: 16.5), PEG-30 glyceryl laurate (HLB: 17.5), PEG-20 glyceryl oleate (HLB: 15.4), PEG-30 glyceryl oleate (HLB: 16.6), polysorbate 20 (HLB: 16.7), polysorbate 40 (HLB: 15.6), polysorbate 60 (HLB: 15.7), polysorbate 80 (HLB: 15.7), PEG-20 sorbitan isostearate (HLB: 15.7), isostearate PEG-20 Glyceryl Isostearate (HLB: 15.4), PEG-30 Glyceryl Isostearate (HLB: 16.8), PEG-60 Glyceryl Isostearate (HLB: 18.1), Sorbet-6 Laurate (HLB: 15.5), Laureth-21 (HLB: 19), Laureth-25 (HLB: 19.5), Ceteth-15 (HLB: 15.5), Ceteth-20 (HLB: 17), Ceteth-23 (HLB: 18), Ceteth-25 (HLB: 18.5), Ceteth-30 (HLB: 19.5), Ceteth Examples include PEG-40 (HLB:20), Steareth-20 (HLB:18), Oleth-15 (HLB:16), Oleth-20 (HLB:17), Oleth-50 (HLB:18), Beheneth-20 (HLB:16.5), Beheneth-30 (HLB:18), PEG-25 stearate (HLB:15), PEG-40 stearate (HLB:17.5), PEG-45 stearate (HLB:18), PEG-55 stearate (HLB:18), and PEG-75 stearate (HLB:18.3).

[0039] Of these, it is preferable to include one or more selected from fatty acid polyoxyethylene sorbitan and polyethylene glycol fatty acid esters, and among polyethylene glycol fatty acid esters, it is preferable to include fatty acid polyoxyethylene monoester. Furthermore, from the viewpoint of improving emulsification stability under high temperature conditions and enhancing a fresh feel, it is even more preferable to combine fatty acid polyoxyethylene sorbitan and fatty acid polyoxyethylene monoester. In addition, polysorbate 60 and polysorbate 80 are more preferably used as fatty acid polyoxyethylene sorbitan, and PEG-45 stearate, PEG-55 stearate, and PEG-75 stearate are more preferably used as fatty acid polyoxyethylene monoesters.

[0040] In the oil-in-water type sunscreen cosmetic of the present invention, the content of component (D), a polyoxyethylene-additive type nonionic surfactant, is preferably 0.2 to 8% by mass. By increasing the content of component (D) to 0.2% by mass or more, the emulsification stability under high-temperature conditions is further improved. From this viewpoint, it is preferable that the content of component (D) be 0.5% by mass or more, and more preferably 1% by mass or more. Furthermore, by decreasing the content of component (D) to 8% by mass or less, the refreshing feel and skin absorption upon application are further improved. From this viewpoint, it is preferable that the content of component (D) be 6% by mass or less, and more preferably 5% by mass or less.

[0041] ((E): At least one of a whitening agent and an anti-inflammatory agent) The (E) whitening agent and anti-inflammatory agent included in the present invention may each be those that have been conventionally used in topical skin preparations such as cosmetics. The whitening agent that may be included in the oil-in-water type sunscreen cosmetic according to the present invention is not particularly limited, but it is preferable to include one or more selected from the group consisting of L-ascorbic acid and its derivatives, tranexamic acid and its derivatives, alkoxysalicylic acid and its derivatives, and nicotinic acid and its derivatives.

[0042] Examples of derivatives of L-ascorbic acid include sodium L-ascorbate, magnesium L-ascorbic acid ester salt, L-ascorbic acid glucoside, 2-O-ethyl-L-ascorbic acid, and 3-O-ethyl-L-ascorbic acid, but among these, L-ascorbic acid glucoside is particularly preferred.

[0043] Examples of tranexamic acid and its derivatives include trans-4-(trans-aminomethylcyclohexanecarbonyl)aminomethylcyclohexanecarboxylic acid hydrochloride, 4-(trans-aminomethylcyclohexanecarboxylic acid 4'-hydroxyphenyl ester), 2-(trans-4-aminomethylcyclohexylcarbonyloxy)-5-hydroxybenzoic acid, trans-4-aminomethylcyclohexanecarboxylic acid methylamide, trans-4-(p-methoxybenzoyl)aminomethylcyclohexanecarboxylic acid, and trans-4-guanidinomethylcyclohexanecarboxylic acid. Among these, tranexamic acid is particularly preferred.

[0044] Examples of alkoxysalicylic acids and their derivatives include 3-methoxysalicylic acid, 3-ethoxysalicylic acid, 4-methoxysalicylic acid, 4-ethoxysalicylic acid, 4-propoxysalicylic acid, 4-isopropoxysalicylic acid, 4-butoxysalicylic acid, 5-methoxysalicylic acid, 5-ethoxysalicylic acid, or 5-propoxysalicylic acid, or salts of these alkoxysalicylic acids.

[0045] Examples of nicotinic acid derivatives include benzyl nicotinate, nicotinamide, and dl-α-tocopherol nicotinate, but among these, nicotinamide is particularly preferred.

[0046] Examples of anti-inflammatory agents include glycyrrhizic acid and its derivatives, glycyrrhetinic acid and its derivatives, salicylic acid and its derivatives, and ufenamate. Among these, it is preferable to include glycyrrhizic acid and its derivatives. Examples of glycyrrhizic acid derivatives include dipotassium glycyrrhizate and monoammonium glycyrrhizate, with dipotassium glycyrrhizate being particularly preferred.

[0047] In the present invention, the content (total value) of at least one of the whitening agent and the anti-inflammatory agent is not particularly limited, but is preferably 0.01 to 5% by mass relative to the total amount of the oil-in-water type sunscreen cosmetic.

[0048] (F): Polyols with a molecular weight of 500 or less and with a valent or higher nucleotide. Furthermore, in the oil-in-water type sunscreen cosmetic composition of the present invention, it is even more preferable to include (F) a trivalent or higher polyol with a molecular weight of 500 or less, from the viewpoint of enhancing the effects of the present invention. Examples of (F) trivalent or higher polyols with a molecular weight of 500 or less include glycerin, diglycerin, triglycerin, polyglycerin with a molecular weight of 500 or less, glucose, maltose, sucrose, xylitol, sorbitol, maltitol, polyoxyethylene methyl glucoside with a molecular weight of 500 or less, polyoxyethylene ethyl glucoside with a molecular weight of 500 or less, and polyoxyethylene propylene glucoside with a molecular weight of 500 or less, and other sugars or sugar alcohols. Of these, glycerin is more preferred.

[0049] In the oil-in-water type sunscreen cosmetic composition of the present invention, the content of (F) trivalent or higher polyol with a molecular weight of 500 or less is preferably 0.5 to 10% by mass. By setting the content of (F) polyol to 0.5% by mass or more, the dispersibility of the ultraviolet scattering agent is further improved. From this viewpoint, it is even more preferable that the content of (F) polyol be 1% by mass or more. Furthermore, by setting the content of (F) polyol to 10% by mass or less, the emulsification stability under high temperature conditions and the refreshing feel are further improved. From this viewpoint, it is even more preferable that the content of (F) polyol be 6% by mass or less.

[0050] The formulation of the oil-in-water sunscreen cosmetic of the present invention can take any form known as a cosmetic, pharmaceutical, or quasi-drug. Among such known forms, examples include liquids, suspensions, emulsions, creams, gels, aerosols, sheets impregnated with a medicinal solution, and lip emulsions. The external composition of the present invention is preferably an oil-in-water (O / W) composition. Here, an oil-in-water (O / W) composition means an emulsion composition in which the aqueous component is a continuous phase and the oily component is a dispersed phase. Water-based emulsions, aqueous gels, and water-based creams are preferred formulation forms.

[0051] Furthermore, the oil-in-water type sunscreen cosmetic of the present invention may contain additives used in cosmetics, quasi-drugs, pharmaceuticals, etc., as needed, to the extent that they do not impair the effects of the present invention. For example, natural fragrances and synthetic fragrances may be added to enhance palatability. Natural fragrances are essential oils obtained from the flowers, stems, leaves, fruits, peels, and roots of plants by steam distillation, etc., and the separated water can also be used as aromatic water. Synthetic fragrances are not particularly limited and include esters, ethers, aldehydes, ketones, aromatic alcohols, hydrocarbons, etc. Other additives include, for example, glycols such as dipropylene glycol, 1,3-butylene glycol, and polyethylene glycol; oils such as hydrocarbon oils, ester oils, silicone oils, vegetable oils, and UV absorbers (excluding component (C)); lower alcohols such as ethanol and isopropanol; sugars such as lactose and sucrose; anionic surfactants such as acylmethyl taurate salts, alkyl ether sulfate salts, and amide ether sulfate salts; and nonionic surfactants (excluding component (D)); organic or inorganic salts such as citrates, malates, and sodium chloride; acids and alkalis as pH adjusters; preservatives; extracts derived from plants and animals; amino acids; dyes; pigments, etc.

[0052] The method for producing the oil-in-water type sunscreen cosmetic of the present invention is not particularly limited and can be prepared by conventional methods. For example, it can be prepared by mixing a preliminary dispersion containing component (A), component (B), component (F), and water with other aqueous components containing component (E), and then adding it to an oily component containing components (A), component (C), and component (D) and emulsifying it.

[0053] Furthermore, in the present invention, when incorporating hydrophilic component (A), it is preferable to prepare a preliminary dispersion containing component (A), component (B), and component (F) and water in advance, such that the total content of component (A) and component (B) is preferably 10 to 50% by mass, more preferably 20 to 50% by mass, relative to the mass of the preliminary dispersion, and then mix it with other aqueous components to emulsify it with the oily components. By taking such a step, the dispersibility of component (A) can be further enhanced, and the effects of the present invention can be improved. [Examples]

[0054] Each of the oil-in-water sunscreen cosmetic compositions shown in Tables 1 to 3 (Examples 1 to 12 and Comparative Examples 1 to 6) was prepared and evaluated as follows. Tables 1 to 3 show the type and mass ratio (mass%) of each component. The types and content of the 10 common components contained in each oil-in-water sunscreen cosmetic composition are summarized in Table 4.

[0055] The evaluation criteria consisted of five items: "UV protection effect," "dispersibility of UV scattering agent," "emulsification stability under high temperature conditions," "refreshing feel," and "skin absorption upon application." These were evaluated according to the evaluation criteria described below.

[0056] (UV protection effect) The obtained oil-in-water sunscreen cosmetic was placed on a PMMA plate at a concentration of 2 mg / cm². 2 Samples were obtained by coating the samples. After that, the samples were left to stand for 20 minutes under light-shielding conditions, and the SPF was measured using an SPF analyzer (UV-2000S, Labsphere). ○: When the SPF value is 10 or higher and the UV protection effect is sufficient. ×: When the SPF value is less than 10 and the UV protection effect is insufficient.

[0057] (Dispersibility of UV scattering agents) Using the ratios listed in Tables 1-3 for "Preparation of Aqueous Dispersion," a benchtop homomixer (Primix Co., Ltd., Lab-Solution) was used to vigorously stir the mixture at 4000 rpm for 30 minutes to obtain an aqueous dispersion of the ultraviolet scattering agent. The obtained aqueous dispersion was filtered through a 50-mesh filter, and its dispersibility was evaluated by checking the collected material. In detail, the results were rated as "◎" (excellent), "○" (good), and "×" (poor) according to the criteria described below. In this evaluation, "◎" (excellent) and "○" (good) were considered pass, while "×" (poor) were considered fail. ◎: When there is very little collected material and it is highly dispersible. ○: When the amount of collected material is less than 0.2% of the powder amount and the dispersibility is high. ×: When the collected material makes up 0.2% or more of the powder amount and has low dispersibility.

[0058] (Emulsification stability under high-temperature conditions) The oil-in-water type sunscreen cosmetic was obtained, and the stability of the sample was evaluated after it was left to stand for one month under 50°C conditions. ○: When gelation due to aggregation of UV scattering agents does not occur, and the surface is smooth. ×: This occurs when gelation occurs due to aggregation of the UV scattering agent, resulting in a pudding-like solidification and syneresis (water separation).

[0059] (A refreshing feeling when used) Twenty women (ages 25-45) served as panelists, and the uniformity of application of oil-in-water sunscreen cosmetic (2.0g) to the entire hands and arms was evaluated according to the following criteria. Specifically, a total score of 35 points or higher was rated "◎" (Excellent), 25-34 points was rated "○" (Good), 15-24 points was rated "△" (Acceptable), and 14 points or lower was rated "×" (Poor). In this evaluation, products rated "◎" (Excellent) and "○" (Good) were considered pass, while products rated "△" (Acceptable) and "×" (Poor) were considered fail. Points 2: It has no oily feel and a refreshing texture. 1 point: It has almost no oily feel and a slightly refreshing texture. 0 points: It has an oily feel and does not provide a refreshing sensation.

[0060] (How well it blends into the skin when applied) Twenty women (ages 25-45) served as panelists, and their skin absorption of oil-in-water sunscreen cosmetics (2g) applied to the back of their hands was evaluated according to the following criteria. Specifically, a total score of 35 points or higher from the 20 panelists was rated "◎" (Excellent), 25-34 points was rated "○" (Good), 15-24 points was rated "△" (Acceptable), and 14 points or lower was rated "×" (Poor). In this evaluation, products rated "◎" (Excellent) and "○" (Good) were considered pass, while products rated "△" (Acceptable) and "×" (Poor) were considered fail. Two points: No flaky aggregates occur during application, and it blends very well with the skin. 1 point: If a small amount of crumbly aggregates appear during application, but the product blends well into the skin. 0 points: If clumps form during application and the product does not blend well with the skin.

[0061] [Table 1]

[0062] [Table 2]

[0063] [Table 3]

[0064] Here, the specific details of each component listed in "Note 1" to "Note 11" in Tables 1 to 3 are summarized below. Note 1: "SSQP50ZJEJ" (Primary particle size: 20 nm): Manufactured by KOBO Dispatik Co., Ltd. Note 2: "SSQP40TIJ" (Primary particle size: 10 nm): Manufactured by KOBO Dispatik Corporation Note 3: "MT-05" (Primary particle size: 10 nm, silica, hydrated alumina treatment): Manufactured by Teika Co., Ltd. Note 4: "MT-100AQ" (Primary particle size: 10 nm, silica, hydrated alumina, sodium alginate treatment): Manufactured by Teika Co., Ltd. Note 5: "Crown Talc JS" (volume-average particle size 14 μm, bulk density 0.34): Manufactured by Matsumura Sangyo Co., Ltd. Note 6: "Barium Sulfate HL Plates" (average particle size 15 μm): Manufactured by Sakai Chemical Industry Co., Ltd. Note 7: "Matsumoto Microsphere (Registered Trademark) - M" (Average particle size 5-20 nm): Manufactured by Matsumoto Oil & Fat Pharmaceutical Co., Ltd. Note 8: "NOFABLE ESO-8520": Manufactured by NOF Corporation Note 9: "Sunsoft No. 2500C": Manufactured by Taiyo Kagaku Co., Ltd. Note 10: "Sunsoft A-181E-C": Manufactured by Taiyo Kagaku Co., Ltd. Note 11: "Sunsoft A-12E-C": Manufactured by Taiyo Kagaku Co., Ltd.

[0065] [Table 4]

[0066] In all of the Examples 1 to 12, we obtained oil-in-water sunscreen cosmetics that provided sufficient UV protection, exhibited good dispersibility of UV scattering agents and emulsification stability under high-temperature conditions, had a refreshing feel, and blended well with the skin upon application.

[0067] On the other hand, the effects of Comparative Examples 1-6 were not sufficient. In other words, in Comparative Example 1, because (B) plate-shaped powder was not incorporated, the dispersibility of the UV scattering agent and its ability to blend well with the skin during application were reduced. In Comparative Example 2, (B) plate-shaped powder was not included, and instead, (B') spherical powder was included. As a result, the dispersibility of the UV scattering agent and the emulsification stability under high-temperature conditions decreased, and the skin compatibility during application was reduced.

[0068] In Comparative Example 3, (C) oils with a melting point of 35°C or higher and 65°C or lower were not included, and instead (C') oils with a melting point higher than 65°C were included, resulting in reduced skin absorption during application. In Comparative Example 4, (C) oils with a melting point of 35°C or higher and 65°C or lower were not included, and instead (C') oils with a melting point lower than 35°C were included, resulting in a reduced refreshing feel.

[0069] In Comparative Example 5, the (D) polyoxyethylene-added nonionic surfactant was not included, and instead, a (D') nonionic surfactant with a different structure was included. However, the emulsification stability under high-temperature conditions decreased, as did the refreshing feel and skin absorption upon application.

[0070] In Comparative Example 6, the (D) polyoxyethylene-added nonionic surfactant was not included, and instead, a (D') nonionic surfactant with a different structure was included, but the refreshing feeling during use was reduced.

[0071] Tables 5 and 6 show examples of formulations for oil-in-water type sunscreen cosmetics, respectively.

[0072] [Table 5]

[0073] [Table 6]

[0074] The oil-in-water sunscreen cosmetics comprising the compositions described in Tables 5 and 6 provided sufficient UV protection, exhibited good dispersibility of UV scattering agents and emulsification stability under high-temperature conditions, had a refreshing feel, and blended well with the skin upon application. [Industrial applicability]

[0075] The oil-in-water sunscreen cosmetic of the present invention can be applied to skin such as the face and skin, has sufficient UV protection, exhibits good dispersibility of UV scattering agents and emulsification stability under high temperature conditions, has a refreshing feel, and blends well with the skin upon application. Therefore, it can be expected to have a wide range of applications in sunscreen cosmetics.

Claims

1. (A) UV scattering agent, (B) (A) Plate-shaped powder different from ultraviolet scattering agent, (C) Oils with a melting point of 35°C or higher and 65°C or lower, (D) An oil-in-water type sunscreen cosmetic characterized by containing a polyoxyethylene-additive type nonionic surfactant.

2. Furthermore, the oil-in-water type sunscreen cosmetic according to claim 1, characterized in that it contains (E) at least one of a whitening agent and an anti-inflammatory agent.

3. Furthermore, the oil-in-water sunscreen cosmetic composition according to claim 1 or 2, characterized in that it contains (F) a trivalent or greater polyol with a molecular weight of 500 or less.

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