Oil-in-water emulsion cosmetics

Abstract

To provide an oil-in-water type emulsion cosmetic which is suitable as a sunscreen cosmetic having an excellent sunscreen effect, an excellent sense of use and excellent storage stability.SOLUTION: There is provided an oil-in-water type emulsion cosmetic which is an emulsion obtained by dispersing a water phase containing the following components (A) and (F) into an oil phase containing the following components (B), (C), (D) and (E), wherein the content rate of the component (B) in the oil phase is 40 to 70 mass%: (A) 0.1 to 3 mass% of an aqueous polymer containing 2-acrylamide-2-methyl propane sulfonic acid or a salt thereof as a constitutional unit, (B) 10 to 40 mass% of an ultraviolet scattering agent composed of an inorganic powder hydrophobically treated with a trialkoxyalkylsilane, (C) 0.1 to 5 mass% of a polyhydroxystearic acid, (D) 0.1 to 5 mass% of a polyglyceryl fatty acid ester having an HLB value of 5 to 8, (E) 7 to 40 mass% of a liquid oil, and (F) 30 to 80 mass% of water.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to an oil-in-water emulsion cosmetic suitable as a sunscreen, and more specifically to an oil-in-water emulsion cosmetic that has excellent sunscreen effect, feel during use, and storage stability. [Background technology]

[0002] Sunscreen cosmetics typically use organic UV absorbers or UV scattering agents made of inorganic fine particles such as titanium oxide or zinc oxide as sunscreen ingredients. Of these, there are concerns about toxicity when the amount of organic UV absorbers is increased in order to enhance the UV absorption effect, and from the standpoint of prioritizing safety, the use of UV scattering agents made of inorganic fine particles is preferred.

[0003] Oil-in-water and water-in-oil emulsion types are widely used as formulations for sunscreen cosmetics, but among them, oil-in-water sunscreen cosmetics, in which water is the continuous phase, provide a fresh feeling when applied to the skin and are also excellent in terms of spreadability and elongation. On the other hand, oil-in-water emulsions have the drawback of being insufficient in water resistance and storage stability, and attempts have been made to improve these drawbacks.

[0004] For example, Patent Document 1 discloses an oil-in-water emulsion cosmetic containing (A) a fine inorganic powder with a hydrophobic organic surface treatment, (B) a surfactant such as a polyglycerol fatty acid ester with an HLB of 9.5 or less, and an aqueous thickener (see claim 1). This invention uses a specific surfactant with an HLB of 9.5 or less, preferably 8 to 9.5, making it possible to stably blend the hydrophobicized fine inorganic powder into the aqueous phase (see paragraph 0014). Sunscreen O / W creams using surfactants such as polyglyceryl-10 distearate, polyglyceryl-6 oleate, polyglyceryl-2 distearate, and polyglyceryl-10 triisostearate have also been disclosed (see Examples 1 to 16), but most of these have not been prepared using fine inorganic powders in advance. powderThe cosmetic product used in this study uses an aqueous dispersion in which a fine inorganic powder is dispersed in an aqueous medium. When a cosmetic product has a fine inorganic powder dispersed in an aqueous medium, the water evaporates during application, which can easily cause aggregation of the fine inorganic powder, resulting in a white cast (a phenomenon in which the skin appears unnaturally white when applied to the skin). The only example is the sunscreen O / W cream described in Example 15, which is prepared by mixing the fine inorganic powder with other ingredients, such as sorbitan sesquiisostearate (HLB: 4.5) and PEG-12 isostearate (HLB: 12), without dispersing it in an aqueous medium beforehand. Example 15 does not describe a specific preparation method, and it is unclear whether the fine inorganic powder is dispersed in the aqueous phase or the oil phase. However, since the technical feature of the invention is "an oil-in-water emulsion cosmetic product containing a fine inorganic powder with a hydrophobic organic surface treatment in the aqueous phase" (see paragraph 0001), it is believed that the cosmetic product of Example 15, like the other examples, contains a fine inorganic powder in the aqueous phase.

[0005] On the other hand, fine inorganic powders with hydrophobic organic surface treatment BodyOil-in-water emulsion cosmetics dispersed in an oil phase are also known. For example, Patent Document 2 discloses an oil-in-water emulsion cosmetic containing (a) zinc oxide, (b) a crosslinked copolymer of acrylamido-2-methylpropanesulfonic acid and / or a sodium acryloyldimethyltaurate copolymer, (c) a nonionic surfactant and / or a hydrophilic surfactant with an HLB of 10 or higher, (d) water, and (e) a silicone oil, in which (a) zinc oxide is dispersed in an oil system containing (e) silicone oil. This cosmetic contains zinc oxide in the oil phase, and exhibits excellent storage stability (stability over time), a pleasant feel in use, and water resistance (see paragraph 0011). It also states that the excellent storage stability of this cosmetic is achieved by dispersing zinc oxide in the oil system, i.e., the oil phase (see paragraph 0033). However, in the case of this cosmetic, it is essential that silicone oil is contained as at least a part of the oil component, and it is described that good results cannot be obtained if other oil components such as liquid paraffin are used (see Comparative Example 3 in Table 3, paragraph 0055).Furthermore, inorganic fine particles such as zinc oxide generally have high cohesive forces between particles, which increases the viscosity of the oil phase, making it difficult to finely disperse the oil phase in the water phase.

[0006] Patent Document 3 also describes: (a) a silicone surfactant with an HLB of 8 or less that is modified with any of a carboxyl group, an amide group, a pyrrolidone carboxyl group, an ester group, a glycerin group, and a polyglycerin group; 、 An oil-in-water sunscreen cosmetic is disclosed that contains (b) low-viscosity silicone oil, (c) an UV scattering agent consisting of hydrophobically treated inorganic powder, (d) a water-soluble polymer compound, (e) a nonionic surfactant with an HLB of 10 or higher, and (f) water, with component (c) substantially dispersed in the oil phase (see Claim 2). In this cosmetic, the dispersibility of the UV scattering agent in the oil phase is improved by incorporating component (a) as a dispersant for component (c). However, the preparation of this cosmetic requires the use of a specific silicone surfactant and low-viscosity silicone oil, which places constraints on raw materials. Furthermore, the use of a nonionic surfactant with an HLB of 10 or higher as an emulsifier also poses the problem of an unsatisfactory feel when used (see Comparative Example 3 below).

[0007] As described above, oil-in-water emulsion cosmetics in which an ultraviolet scattering agent made of hydrophobized inorganic powder is blended in the oil phase have been known for some time. However, attempts to increase the concentration of the hydrophobized inorganic powder in the oil phase in order to enhance the ultraviolet screening effect have resulted in poor dispersion, and even when commonly used dispersants (for example, polyhydroxystearic acid or sorbitan sesquiisostearate) are used, sufficient dispersibility has not been achieved (see Comparative Example 4 below). [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Japanese Patent Application Laid-Open No. 2016-074660 [Patent Document 2] Japanese Patent Application Laid-Open No. 2005-272389 [Patent Document 3] Japanese Patent Application Laid-Open No. 2014-201569 DISCLOSURE OF THE INVENTION [Problem to be solved by the invention]

[0009] The present invention was completed against this background, and its object is to provide an oil-in-water emulsion cosmetic that has excellent sunscreen effect, a good feeling when used, and excellent storage stability. [Means for solving the problem]

[0010] As a result of intensive research conducted by the present inventors to solve the above-mentioned problems, they discovered that in an oil-in-water emulsion cosmetic in which a hydrophobically treated inorganic powder is dispersed in an oil phase, when a specific hydrophobically treated inorganic powder is used in combination with a specific dispersant and a specific surfactant, good dispersibility can be obtained even when a high concentration of an ultraviolet scattering agent made of inorganic powder is contained, and they have completed the present invention.

[0011] Thus, according to the present invention, there is provided an oil-in-water cosmetic preparation characterized in that an oil phase containing the following components (B), (C), (D), and (E) is dispersed in an aqueous phase containing the following components (A) and (F), and the content of component (B) in the oil phase is 40 to 70 mass %. (A) Aqueous polymer containing 2-acrylamido-2-methylpropanesulfonic acid or a salt thereof as a constituent unit: 0.1 to 3% by mass (B) UV scattering agent consisting of inorganic powder hydrophobized with trialkoxyalkylsilane: 10 to 40% by mass (C) Polyhydroxystearic acid: 0.1 to 5% by mass (D) Polyglycerol fatty acid ester having an HLB value of 5 to 8: 0.1 to 5% by mass, (E) Liquid oil: 7 to 40% by mass (F) Water: 30~80% by mass [Effects of the Invention]

[0012] The oil-in-water emulsion cosmetic of the present invention is excellent in sunscreen effect, feeling in use, and storage stability. BEST MODE FOR CARRYING OUT THE INVENTION

[0013] The oil-in-water emulsion cosmetic of the present invention contains, as essential ingredients, (A) an aqueous polymer containing 2-acrylamido-2-methylpropanesulfonic acid or a salt thereof as a constituent unit, (B) an ultraviolet scattering agent consisting of an inorganic powder that has been hydrophobized with a trialkoxyalkylsilane, (C) polyhydroxystearic acid, (D) a polyglycerol fatty acid ester having an HLB value of 5 to 8, (E) liquid oil, and (F) water. Each of these ingredients will be described in detail below.

[0014] (A: Water-based polymer) The aqueous polymer used as component (A) of the present invention is used to stabilize oil-in-water emulsions, and is preferably a copolymer or crosspolymer containing 2-acrylamido-2-methylpropanesulfonic acid or its salt (hereinafter sometimes abbreviated as "AMPS") as a constituent unit. The term "2-acrylamido-2-methylpropanesulfonic acid" is synonymous with "acryloyldimethyltaurine." Specific examples of aqueous polymers include (ammonium acryloyldimethyltaurate / VP) copolymer, (sodium acryloyldimethyltaurate / VP) crosspolymer, (dimethylacrylamide / sodium acryloyldimethyltaurate) crosspolymer, (acrylamide / sodium acryloyldimethyltaurate) copolymer, (sodium acrylate / sodium acryloyldimethyltaurate) copolymer, and (hydroxyethyl acrylate / sodium acryloyldimethyltaurate) copolymer. Among these, (sodium acrylate / sodium acryloyldimethyltaurate) copolymer and (hydroxyethyl acrylate / sodium acryloyldimethyltaurate) copolymer are preferably used.

[0015] Examples of commercially available aqueous polymers include FLOCARE PSD-30, a (sodium acrylate / sodium acryloyldimethyltaurate) copolymer manufactured by SNF Corporation, SIMULGEL-EG, a dispersion containing this polymer, manufactured by SEPPIC Corporation, and SIMULGEL-NS, a dispersion containing a (hydroxyethyl acrylate / sodium acryloyldimethyltaurate) copolymer.

[0016] The content of component (A) is 0.1 to 3 mass% of the total cosmetic, preferably 0.2 to 2 mass%, and more preferably 0.3 to 1.5 mass%. If the content of component (A) is too low, it is likely to cause phenomena such as separation of the oil and water phases, oil floating, emulsification breakdown, and aggregation, resulting in poor stability. If the content is too high, it becomes difficult to spread on the skin. Note that the mass% of each component in the following explanation is also based on the total cosmetic.

[0017] (B: UV scattering agent) The component (B) used in the present invention is an inorganic powder that has been hydrophobized with a trialkoxyalkylsilane, which is used as an ultraviolet scattering agent. The inorganic powder used as the base material may be any powder that is typically incorporated into sunscreen cosmetics, including, for example, zinc oxide, titanium oxide, cerium oxide, zirconium oxide, and iron oxide. These may be used alone, or two or more may be used in combination, or even a composite of two or more may be used. Among these, zinc oxide or titanium oxide is preferred from the perspective of the feel and finish of the cosmetic. The particle size and shape of the inorganic powder are not particularly limited, but from the perspective of UV protection efficacy, an average primary particle size in the range of 1 to 100 nm is preferred. These particle sizes can be determined as the number-average particle size using a transmission or scanning electron microscope. The inorganic powder may have any geometric shape typically used in sunscreen cosmetics, including spherical, polyhedral, spindle-shaped, acicular, and plate-shaped shapes. These inorganic powders are generally surface-treated with inorganic materials such as alumina and silica to block surface activity and impart dispersibility. While these powders are typically hydrophobized with oils, metal soaps, organopolysiloxanes, fluorine, etc. to impart water repellency and dispersibility, the present invention requires the use of powders treated with trialkoxyalkylsilanes. The effects of the present invention cannot be achieved even if hydrophobized inorganic powders treated with other silicone compounds, such as hydrogen dimethicone, are used instead of trialkoxyalkylsilanes (see Comparative Example 6).

[0018] Trialkoxyalkylsilane is a compound in which three alkoxy groups and one alkyl group are bonded to a silicon atom, and the alkoxy groups react with hydroxyl groups on the powder surface to coat the powder surface. Such trialkoxyalkylsilanes are represented by the following general formula (1): CH3(CH2) m S i (O(C n H 2n +1))3(1) (m and n are each a positive integer, m = 5 to 20, n = 1 to 3). Preferred alkoxy groups have 1 to 3 carbon atoms, specific examples of which include a methoxy group, an ethoxy group, and a propoxy group. Preferred alkyl groups have 6 to 18 carbon atoms, specific examples of which include a hexyl group, an octyl group, a decyl group, and an octadecyl group. Examples of such trialkoxyalkylsilanes include trimethoxyhexylsilane, trimethoxyoctylsilane, trimethoxydecylsilane, trimethoxyoctadecylsilane, triethoxyhexylsilane, triethoxyoctylsilane (cosmetics labeling name: triethoxycaprylylsilane), triethoxydecylsilane, and triethoxyoctadecylsilane. These can be used alone or in combination of two or more.

[0019] Among these, trialkoxyalkylsilanes in which the alkyl group has 8 to 22 carbon atoms are preferred because they improve the dispersibility of component (B) in the oil phase, and particularly excellent dispersibility can be obtained by using triethoxycaprylylsilane, in which m = 7 and n = 2 in the above general formula (1).

[0020] The fine powder surface-coated with trialkoxyalkylsilane (B) can be a commercially available product. Examples of commercially available products include MTX-05OTS (average particle size 10 nm), a titanium oxide fine particle coated with triethoxycaprylylsilane, manufactured by Teika Co., Ltd., and MZX-508OTS (average particle size 25 nm) and MZX-304OTS (average particle size 35 nm), both of which are zinc oxide fine particles coated with triethoxycaprylylsilane, manufactured by Teika Co., Ltd.

[0021] The content of component (B) is 10 to 40% by mass, preferably 12 to 38% by mass, more preferably 15 to 35% by mass, and even more preferably 18 to 35% by mass. If the content of component (B) is too low, a high sunscreen effect cannot be obtained, whereas if it is too high, the viscosity of the oil phase increases, making it impossible to obtain fine emulsified particles, reducing storage stability and ease of spread on the skin.

[0022] The mass ratio of the powder component in the oil phase containing component (B) to the entire oil phase (the proportion of the powder component in the oil phase) is 40 to 70 mass%, preferably 50 to 60 mass%. When the amount of component (B) is within this range, high sunscreen effect, excellent feel in use (easy spreadability and a moisturizing feel), and storage stability can be achieved.

[0023] (C: Polyhydroxystearic acid) In the present invention, (C) polyhydroxystearic acid is used as a dispersant for inorganic powders contained in the oil phase. Polyhydroxystearic acid is a polymer of hydroxystearic acid having one hydroxyl group. In the present invention, the hydroxyl group of the hydroxystearic acid is preferably at the 12-position, and the degree of polymerization of the hydroxystearic acid is preferably 3 to 12, more preferably 4 to 8. By including component (C), even when a large amount of inorganic powder (B) is incorporated into the oil phase, an increase in the viscosity of the oil phase is suppressed, making it possible to achieve excellent usability and storage stability. An example of a commercially available product of component (C) is Salacos HS-6C (manufactured by The Nisshin Oillio Group, Ltd.). The content of component (C) is 0.1 to 5% by mass, preferably 0.2 to 3% by mass, and more preferably 0.3 to 2% by mass. If the content of component (C) is too low, the dispersion of component (B) will be insufficient, resulting in poor usability and storage stability. If the content of component (C) is too high, stickiness will occur.

[0024] (D: Polyglycerol fatty acid ester) In the present invention, in order to stabilize the oil-in-water emulsion, (D) a polyglycerol fatty acid ester having an HLB value of 5 to 8, preferably 6 to 7.5, is contained in the oil phase. The presence of component (D) in the oil phase allows the oil phase containing a large amount of fine particle powder to be stably dispersed in the aqueous phase, achieving a fresh, moisturizing feel with good spreadability and high storage stability.

[0025] The fatty acid that is the hydrophobic group portion of the polyglycerol fatty acid ester preferably has 12 to 30 carbon atoms, more preferably 16 to 22 carbon atoms. The fatty acid may be a saturated or unsaturated fatty acid, and may or may not have a branched carbon chain, but is preferably an unsaturated fatty acid or a saturated branched fatty acid. The hydrophilic group portion of the polyglycerol fatty acid ester preferably has a degree of polymerization of glycerin of 2 to 20, more preferably 4 to 15, and particularly preferably 10.

[0026] The HLB value of the polyglycerol fatty acid ester is 5 to 8, preferably 6 to 7.5. An HLB value within this range allows for stable dispersion of an oil phase containing a large amount of fine powder in an aqueous phase, resulting in a fresh, smooth feel when used and high storage stability. However, if a polyglycerol fatty acid ester with an HLB value greater than 8 or less than 5 is used, it becomes difficult to obtain fine emulsion droplets, resulting in insufficient feel when used and storage stability. The HLB index is a value ranging from 0 to 20 that indicates the balance between hydrophilicity and lipophilicity of a nonionic surfactant, with values closer to 0 indicating higher lipophilicity and values closer to 20 indicating higher hydrophilicity. Various methods are known for calculating the HLB value, and the values are also listed in catalogs provided by manufacturers. In this specification, the HLB value of a nonionic surfactant is the HLB value listed in the manufacturer's catalog if the nonionic surfactant is a commercially available product, and if the surfactant is not a commercially available product, the value calculated by the Griffin method (HLB value = 20 × sum of formula weights of hydrophilic moieties / molecular weight) listed on page 307 of "Surfactant Handbook" (published by Sangyo Tosho Co., Ltd., 1960) is used.

[0027] Preferred examples of such polyglycerol fatty acid esters include polyglyceryl-10 trioleate, polyglyceryl-6 diisostearate, polyglyceryl-10 tristearate, polyglyceryl-2 sesquicaprylate, polyglyceryl-4 stearate, polyglyceryl-10 triisostearate, and polyglyceryl-10 pentaisostearate, with polyglyceryl-10 trioleate being particularly preferred. One or more of these may be used as desired. Examples of commercially available products of component (D) include NIKKOL Decaglyn 3-OV (manufactured by Nikko Chemicals Co., Ltd., polyglyceryl-10 trioleate, HLB value 7), EMALEX DISG-6 (manufactured by Nippon Emulsion Co., Ltd., polyglyceryl-6EX diisostearate, HLB value 8), and NIKKOL Decaglyn 3-SV (manufactured by Nikko Chemicals Co., Ltd., polyglyceryl-10 tristearate, HLB value 7.5).

[0028] The content of component (D) is 0.1 to 5% by mass, preferably 0.2 to 3% by mass, and more preferably 0.3 to 2% by mass. If the content of component (D) is too low, the feeling in use and storage stability will decrease. If the content of component (D) is too high, stickiness will occur.

[0029] (E: Liquid oil) In the oil-in-water sunscreen cosmetic of the present invention, a liquid oil (E) is used to disperse the inorganic powder of the sunscreen component (B) and spread it over the skin. Here, "liquid oil" refers to oil that is fluid at room temperature (25°C) and semi-solid oil with a melting point of less than 50°C.

[0030] The liquid oil component (E) used in the present invention is not particularly limited as long as it is one that is commonly used in cosmetics, and may be any of animal oil, vegetable oil, and synthetic oil. Specific examples of liquid oils include esters such as triethylhexanoin, caprylic / capric triglyceride, neopentyl glycol dicaprate, isononyl isononanoate, isotridecyl isononanoate, ethylhexyl palmitate, isopropyl myristate, isopropyl palmitate, octyldodecyl myristate, diisostearyl malate, oligomer esters of dimer acid and dimer diol, pentaerythritol tetraisostearate, diglyceryl tetraisostearate, cetyl isooctanoate, cholesterol fatty acid esters, and jojoba oil; hydrocarbons such as volatile isoparaffin, polybutene, polyisobutylene, heavy liquid isoparaffin, liquid paraffin, α-olefin oligomer, squalane, and petrolatum; oils and fats such as olive oil, castor oil, mink oil, and macadamia nut oil; and fatty acids such as isostearic acid and oleic acid. Examples include higher alcohols such as oleyl alcohol and isostearyl alcohol; silicone oils such as low-polymerization dimethylpolysiloxane, cyclic silicone, high-polymerization dimethylpolysiloxane, methylphenylpolysiloxane, methyl trimethicone, caprylyl trimethicone, crosslinked organopolysiloxane, and fluorine-modified polysiloxane; fluorine-based oils such as perfluoropolyether; and lanolin derivatives such as lanolin, lanolin acetate, lanolin fatty acid isopropyl, and lanolin alcohol.

[0031] The viscosity of the liquid oil at 25°C is usually 1 to 200 mPa·s, preferably 5 to 100 mPa·s, with ester oil being particularly preferred. The viscosity of the liquid oil is measured using a Brookfield viscometer. Specific examples of ester oils include triethylhexanoin, caprylic / capric triglyceride, neopentyl glycol dicaprate, isononyl isononanoate, isotridecyl isononanoate, ethylhexyl palmitate, and isopropyl myristate. The content of ester oils having a viscosity of 1 to 200 mPa·s at 25°C is preferably 10 to 100% by mass of the total liquid oil.

[0032] The content of (E) liquid oil is preferably 7 to 40% by mass, more preferably 10 to 35% by mass, and even more preferably 12 to 30% by mass. If the content of (E) component is too low, it becomes difficult to disperse the fine metal oxide particles of (B) component, and the ease of spreading decreases. If the content is too high, the product lacks freshness and feels sticky when used.

[0033] (oil phase) In the oil-in-water sunscreen cosmetic of the present invention, the oil phase contains the components (B) to (E) used in the present invention as essential components, and may also contain oil-soluble components and oil-dispersible components used in ordinary cosmetics.

[0034] Examples of oil-soluble and oil-dispersible ingredients that can be blended include organic ultraviolet absorbers, solid oils, lipophilic nonionic surfactants other than component (D) with an HLB value of 8 or less, oil-soluble resins, oil-soluble antioxidants, oil-soluble vitamins, oil-soluble animal and plant extracts and other oil-soluble active ingredients, and powders other than component (B).

[0035] Since organic UV absorbers are more likely to irritate the skin than inorganic fine powders, when organic UV absorbers are used, their amount is preferably 4% by mass or less, and particularly 3% by mass or less, relative to the total cosmetic composition, and it is most preferable that they are not used at all.

[0036] Examples of powders other than component (B) include inorganic powders such as pigment-grade titanium oxide, iron oxide, talc, and mica; organic powders such as polymer powders and metal soaps; pigment powders such as tar-based pigments, metal powders; and composite powders. From the viewpoints of storage stability and usability, it is preferable that the powder surface is hydrophobic or lipophilic, or has been subjected to a hydrophobic or lipophilic treatment.

[0037] In the oil-in-water sunscreen cosmetic of the present invention, the content of the oil phase is preferably 20 to 70% by mass, more preferably 25 to 60% by mass, and even more preferably 30 to 50% by mass, based on the total mass of the sunscreen cosmetic. If the oil phase content is too low, it will be impossible to incorporate a large amount of inorganic powder, resulting in inferior sunscreen efficacy. If the oil phase content is too high, the product will lack moisture and feel sticky in use, and its storage stability will also be reduced.

[0038] (aqueous phase) In the oil-in-water sunscreen cosmetic of the present invention, the aqueous phase can contain, in addition to the aqueous polymer of component (A) and water of component (F), water-soluble and water-dispersible components used in conventional cosmetics. Examples of water-soluble or water-dispersible components that can be incorporated include lower alcohols, polyhydric alcohols, water-soluble polymers other than component (A), hydrophilic nonionic surfactants, water-soluble active ingredients such as water-soluble vitamins and water-soluble animal and plant extracts, pH adjusters, chelating agents, water-soluble antioxidants, and water-soluble antibacterial agents.

[0039] In the oil-in-water sunscreen cosmetic of the present invention, it is preferable that the aqueous phase contains a hydrophilic surfactant as component (G). By including a hydrophilic surfactant, it becomes easier to obtain a stable oil-in-water emulsion. Examples of hydrophilic surfactants include anionic surfactants, amphoteric surfactants, and nonionic surfactants with an HLB value of more than 8.

[0040] Specific examples of anionic surfactants include higher fatty acid salts such as sodium stearate, acylated amino acid salts such as sodium stearoyl glutamate and sodium lauroyl glycine, alkyl ether carboxylates, and alkyl sulfates.

[0041] Examples of amphoteric surfactants include aminoacetic acid betaine type amphoteric surfactants such as lauryl betaine, aminopropionic acid type amphoteric surfactants such as lauramidopropyl betaine, and sulfobetaine type amphoteric surfactants such as lauryl hydroxysultaine.

[0042] Examples of nonionic surfactants with an HLB value of greater than 8 include polyglycerin fatty acid esters such as polyglyceryl-10 laurate, polyglyceryl-10 myristate, and polyglyceryl-10 oleate; polyoxyethylene hydrogenated castor oils such as PEG-60 hydrogenated castor oil; polyoxyethylene fatty acid esters such as PEG-10 oleate; polyoxyethylene fatty acid glyceryl such as PEG-15 glyceryl oleate; polyoxyethylene alkyl ethers; fatty acid polyoxyethylene alkyl ethers; polyoxyethylene sorbitan fatty acid esters; polyoxyethylene polyoxypropylene copolymers; ethers of polyoxyethylene polyoxypropylene copolymers and long-chain alcohols; and ethers of polybutylene glycol polyglycerin copolymers and long-chain alcohols.

[0043] Among these hydrophilic surfactants, nonionic surfactants having an HLB value of more than 8 are preferably used, and among these, polyglycerin fatty acid esters, polyoxyethylene fatty acid esters, polyoxyethylene fatty acid glyceryl and polyoxyethylene hydrogenated castor oil are preferably used.

[0044] When a hydrophilic surfactant is used, its content is preferably 0.1 to 3% by mass relative to the total amount of the cosmetic. When a hydrophilic surfactant is contained, the stability of the emulsion is improved, but if the content is too high, the water resistance of the coated film is reduced.

[0045] In the oil-in-water sunscreen cosmetic of the present invention, it is preferable that the aqueous phase contains a polyhydric alcohol as component (H). The inclusion of a polyhydric alcohol enhances skin moisturizing properties and makes it easier to obtain a stable oil-in-water emulsion. Examples of polyhydric alcohols include glycerin, diglycerin, propylene glycol (cosmetics labeling name: PG), dipropylene glycol (cosmetics labeling name: DPG), propanediol, butylene glycol (cosmetics labeling name: BG), sorbitol, xylitol, polyethylene glycol, etc. The content of component (H) is preferably 2 to 30% by mass.

[0046] Examples of water-soluble polymers other than component (A) include carboxyvinyl polymer, sodium polyacrylate, acrylic acid / alkyl methacrylate copolymer, hydroxyethyl cellulose, hydroxypropyl methylcellulose, guar gum, carrageenan, xanthan gum, pullulan, etc. Of these, nonionic water-soluble polymers such as xanthan gum, hydroxyethyl cellulose, hydroxypropyl methylcellulose, and pullulan are preferably used because they are less susceptible to the influence of polyvalent metal ions derived from the fine particle metal oxide, which is an essential component.

[0047] Although the aqueous phase may contain a fine inorganic powder as long as it does not substantially impair the effects of the present invention, the presence of inorganic powder in the aqueous phase reduces the freshness and ease of spreadability of the cosmetic, and the inorganic powder is more likely to aggregate on the skin than when the same amount of fine metal oxide is contained in the oil phase, increasing the ability to mask visible light and causing a whitish cast. Therefore, when fine inorganic powder is contained in the aqueous phase, its content is 5% by mass or less, preferably 1% by mass or less, of the total cosmetic composition, and it is particularly preferred that the fine inorganic powder is substantially absent from the aqueous phase.

[0048] In the oil-in-water emulsion cosmetic of the present invention, the content of the aqueous phase is preferably 30 to 80% by mass, more preferably 40 to 75% by mass, and even more preferably 50 to 70% by mass, based on the total mass of the cosmetic. If the aqueous phase content is too low, the cosmetic will lack freshness, feel sticky when used, and have reduced storage stability. If the aqueous phase content is too high, the cosmetic will not be able to contain a large amount of fine particle metal oxide, resulting in reduced sunscreen effect.

[0049] The emulsion cosmetic of the present invention can be prepared according to conventional methods. For example, an oil phase containing components (B) to (D) and an aqueous phase containing component (A) are separately prepared, and the oil phase is added to the aqueous phase or the aqueous phase is added to the oil phase while stirring to emulsify. Adding the oil phase to the aqueous phase makes it easier to obtain an emulsion with excellent storage stability than the reverse.

[0050] Furthermore, when the aqueous phase contains a hydrophilic surfactant (G) and a polyhydric alcohol (H), the emulsion can be prepared by a method in which a mixture containing these components, called a D phase (surfactant phase), is first formed, and then an oil phase is gradually added with stirring to form a gel emulsion (O / D phase), to which the aqueous phase is then added to form an oil-in-water emulsion (hereinafter referred to as the D-phase emulsification method). Production using the D-phase emulsification method results in a stable emulsion with a small particle size, which has good spreadability and is easy to apply on the skin, and can efficiently produce a cosmetic that provides a fresh and moist feel. In the D-phase emulsification method, the D phase is prepared by mixing the components (G) and (H) in advance. However, since both the components (G) and (H) are hydrophilic, their amounts are treated as part of the amount of the aqueous phase in the present invention.

[0051] The oil-in-water sunscreen cosmetic of the present invention may be in any form, such as a cream, gel, emulsion, or liquid (thin emulsion). This cosmetic can be used not only as a sunscreen cosmetic, but also as other cosmetics imparted with UV protection. Specific examples of other cosmetics include makeup cosmetics such as foundations and primers, skin care cosmetics such as emulsions, creams, serums, BB creams, and CC creams, and hair cosmetics. [Example]

[0052] The present invention will be described in more detail below with reference to examples and comparative examples, but the present invention is not limited to these examples. In the following description, the blending amounts in the formulations are expressed in mass % of the total amount unless otherwise specified.

[0053] The oil-in-water sunscreen cosmetics in the following examples and comparative examples were evaluated as follows.

[0054] (Evaluation methods a-c) For the following evaluation items a to c, 10 evaluators applied each sample to their faces and performed a sensory evaluation on a four-level scale based on the following scoring criteria (scores).

[0055] (Evaluation items) a. Ease of stretching b. Freshness c. No white cast

[0056] (Score) 5 points: Excellent. 4 points: Excellent. 3 points: Average. 2 points: Poor. 1 point: Very poor. (Evaluation criteria) A: Average score of 4.0 or above B: Average score between 3.5 and 4.0 C: Average score between 2.5 and 3.5 D: Average score below 2.5 points

[0057] (Evaluation method: viscosity stability) After preparing the water-based emulsion cosmetics of the Examples and Comparative Examples, the viscosity was measured the next day (initial viscosity) and after storing at 40°C for one week, at 25°C using a B-type viscometer (TVB-10M; manufactured by Toki Sangyo Co., Ltd.) The viscosity change rate (%) was calculated as 100 × (viscosity after storing at 40°C for one week) / (initial viscosity), and evaluated according to the following criteria.

[0058] (Evaluation criteria) A: Viscosity change rate: 70% or more B: Viscosity change rate: 50% or more and less than 70% C: Viscosity change rate: less than 50% D: A uniform oil-in-water emulsion composition was not obtained immediately after preparation.

[0059] Example 1 ~3 and Comparative Examples 1 to 8 <Sunscreen lotion> The sunscreen emulsions shown in Table 1 were prepared according to the following manufacturing procedure (D-phase emulsification method) and evaluated using the above-mentioned evaluation methods. The results are also shown in Table 1. In Comparative Example 3, 1.00% of polyglyceryl-10 laurate, a hydrophilic surfactant, was used in preparing the oil phase (ingredient number 15). However, since polyglyceryl-10 laurate is not thought to be present in the oil phase at the time the emulsion was prepared, its amount was treated as part of the amount of the aqueous phase. (Manufacturing Procedure) (1) Components 1 to 3 are mixed to prepare Phase D (a). (2) Components 4 to 15 are mixed to prepare oil phase (b). (3) Components 16 to 22 are mixed to prepare aqueous phase (c). (4) At room temperature, the oil phase (b) is mixed into the D phase (a) in small amounts to prepare a gel-like emulsion O / D phase (e). (5) The O / D phase (e) is mixed with the water phase (c) to prepare a cosmetic. Sample 3-6 Polyisobutene (hydrocarbon oil, trade name: Pearleem 24, manufactured by NOF Corporation)

[0060] [Table 1]

[0061] *1: Product name: NIKKOL Decaglyn 1-L (Nikko Chemicals Co., Ltd.) *2: Product name: Sunsoft Q-14Y-C (Taiyo Kagaku Co., Ltd.) *3: Product name: MTX-05OTS (Teika Co., Ltd.) *4:Product name MZX-304OTS (Teika) *5: Product name MTY-110M3S (Teika Co., Ltd.) *6: Product name: MZY-303S (Teika Co., Ltd.) *7: Product name: Salakos HS-6C (Nisshin Oillio Co., Ltd.) *8: Product name: NIKKOL SI-15RV (Nikko Chemicals Co., Ltd.) *9: Product name: KF-6017 (Shin-Etsu Chemical Co., Ltd.) *10: Product name: NIKKOL Decaglyn 3-OV (Nikko Chemicals) *11: Product name: EMALEX GWS-315 (Nihon Emulsion Co., Ltd.) *12: Product name: KF-6013 (Shin-Etsu Chemical Co., Ltd.) *13:Product name FLOCARE PSD 30 (SNF)

[0062] As is clear from the results in Table 1, the oil-in-water sunscreen cosmetics of the present invention were excellent in terms of spreadability, moisture, absence of cast, and storage stability (Examples 1 to 3). On the other hand, the cosmetics that did not contain a polyglycerol fatty acid ester (D) component with an HLB value of 5 to 8 in the oil phase (Comparative Example 1), the cosmetics that used a polyoxyethylene fatty acid ester with an HLB value of 7 instead of component (D) (Comparative Example 2), and the cosmetics that incorporated polyglycerol fatty acid ester polyglyceryl-10 laurate (HLB 15.5) during the preparation of the oil phase (Comparative Example 3) were unsatisfactory in terms of spreadability and moisture. Furthermore, the cosmetics of Comparative Examples 4 and 5, in which the polyhydroxystearic acid (C) component was replaced with other dispersants, sorbitan sesquiisostearate and PEG-10 dimethicone, respectively, were inferior in terms of spreadability and moisture, and their viscosity stability was also unsatisfactory. Furthermore, when titanium oxide hydrophobized with hydrogen dimethicone was used as the fine inorganic powder, not only was there a problem with emulsion stability, but the ease of spreading, freshness, and absence of white cast were also insufficient (Comparative Example 6). When fine zinc oxide particles were dispersed in the aqueous phase, the freshness was inferior and white cast was noticeable (Comparative Example 7). When the proportion of component (B) in the oil phase was low, the freshness was inferior (Comparative Example 8).

[0063] Example 4 <Makeup base> Makeup bases with the formulations shown in Table 2 were prepared using the same manufacturing procedure (D-phase emulsification method) as above and evaluated using the evaluation methods described above. The results are shown in Table 2 along with the formulations. Note that component numbers 6 to 9 in Table 2 are pigments for coloring.

[0064] [Table 2]

[0065] *14:Product name OTS-2 TiO2 PFC407 (Daito Kasei Kogyo Co., Ltd.) *15:Product name OTS-2 RED R-516P (Daito Kasei Kogyo Co., Ltd.) *16: Product name OTS-2 YELLOW LL-100P (Daito Kasei Kogyo Co., Ltd.) *17: Product name: OTS-2 BLACK BL-100P (Daito Kasei Kogyo Co., Ltd.)

[0066] As is clear from the results in Table 2, the makeup base of Example 4 was excellent in terms of ease of spreadability, freshness, absence of white cast, and storage stability. [Industrial Applicability]

[0067] According to the present invention, there is provided an oil-in-water cosmetic composition which is excellent in sunscreen effect, feeling in use, and storage stability, and is suitable as a sunscreen cosmetic composition.

Claims

1. An oil-in-water emulsion cosmetic is an emulsion in which an oil phase containing the following components (B), (C), (D), and (E) is dispersed in an aqueous phase containing the following components (A) and (F), and the content of component (B) in the oil phase is 40 to 70% by mass. (A) Aqueous polymer containing 2-acrylamido-2-methylpropanesulfonic acid or a salt thereof as a constituent unit: 0.1 to 3% by mass (B) an ultraviolet scattering agent composed of an inorganic powder hydrophobized with trialkoxyalkylsilane: 10 to 40 mass %, (C) polyhydroxystearic acid: 0.1 to 5% by mass, (D) Polyglycerol fatty acid ester having an HLB value of 6 to 8: 0.1 to 5% by mass (E) Liquid oil: 7 to 40% by mass (F) Water: 30 to 80% by mass

2. 2. The oil-in-water emulsion cosmetic according to claim 1, wherein the content of the oil phase is 20 to 70% by mass and the content of the water phase is 30 to 80% by mass.

3. 3. The oil-in-water emulsion cosmetic according to claim 1, which is substantially free of an organic ultraviolet absorber.

4. 4. The oil-in-water emulsion cosmetic according to claim 1, further comprising 0.1 to 3% by mass of a hydrophilic surfactant (G).

5. The oil-in-water emulsion cosmetic according to any one of claims 1 to 4, further comprising 2 to 30% by mass of a polyhydric alcohol (H).

6. 6. The oil-in-water emulsion cosmetic according to claim 1, wherein the content of component (B) in the oil phase is 50 to 70% by mass.

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