Water-in-oil emulsified skin cosmetics

Abstract

The present invention aims to provide a water-in-oil emulsified skin cosmetic that improves its UV protection effect compared to immediately after application upon contact with water, sweat, or other moisture, and provides an excellent feel during use. The water-in-oil emulsified skin cosmetic of the present invention is characterized in that it contains: (A) (a-1) a copolymer and / or (a-2) a silylated peptide; and (B) a UV protection agent, wherein the (a-1) copolymer has: a silanol group; and: a propylene oxide (PO) group or an ethylene oxide (EO) group.

Description

Technical Field

[0001] The present invention relates to a water-in-oil emulsified skin cosmetic. More specifically, it relates to a water-in-oil emulsified skin cosmetic that contains a UV protection agent and, upon contact with moisture such as water and sweat, exhibits improved UV protection compared to that immediately after application and also provides an excellent feel during use. Background Art

[0002] Protecting the skin from UV damage is one of the most important issues in skincare and body care. Various UV care cosmetics have been developed to minimize the adverse effects of UV on the skin. Sunscreen cosmetics, one type of UV care cosmetic, are designed to protect the skin from the adverse effects of UV by covering the skin with a coating containing UV absorbers and UV scatterers. This coating absorbs or scatters UVA and UVB rays from sunlight, thereby reducing the amount of UV rays reaching the skin (Non-Patent Document 1).

[0003] Sunscreen cosmetics applied to the skin are exposed to various types of water, such as sweat and seawater secreted by the skin. Consequently, UV absorbers and UV scatterers are likely to flow out of the cosmetic film applied to the skin, inevitably reducing the UV protection effect. Therefore, water-in-oil emulsions are preferred due to their excellent water resistance.

[0004] For example, Patent Document 1 describes that by adding an oil-phase thickener to a sunscreen cosmetic containing a UV protection agent, it possesses the following unique property, which was previously unavailable: after the cosmetic coating film comes into contact with moisture such as water and sweat, the UV protection effect is improved compared to the immediate period after application (before contact with moisture). However, when the cosmetics described in Patent Document 1 are manufactured as a water-in-oil emulsion, the addition of the oil-phase thickener increases the viscosity of the external phase, resulting in a tendency for the product to feel sticky. Therefore, further improvements are desired, particularly from the perspective of the feel during use.

[0005] Prior art literature

[0006] Patent Literature

[0007] Patent Document 1: International Publication No. 2016 / 068300

[0008] Non-patent literature

[0009] Non-Patent Literature 1: "New Cosmetic Science," 2nd edition, edited by Takeo Mitsui, 2001, published by Nanzando, pp. 497-504 Summary of the Invention

[0010] Problems to be solved by the invention

[0011] An object of the present invention is to provide a water-in-oil emulsified skin cosmetic having the property of improving the UV protection effect compared to that immediately after application by contact with moisture such as water and sweat, and also having an excellent feel during use.

[0012] Solutions for solving problems

[0013] The present inventors have conducted intensive studies to solve the aforementioned problems and have discovered that by incorporating a copolymer and / or a silylated peptide into a water-in-oil emulsified skin cosmetic containing a UV protection agent, wherein the copolymer has a silanol group and a propylene oxide (PO) group or an ethylene oxide (EO) group, the UV protection effect is significantly improved upon contact with moisture such as water and sweat, and an excellent feeling during use is also exhibited, thereby completing the present invention.

[0014] That is, the present invention provides

[0015] A water-in-oil emulsified skin cosmetic comprising: (A) at least one selected from (a-1) a copolymer and (a-2) a silylated peptide, and (B) an ultraviolet protection agent.

[0016] The (a-1) copolymer has: a silanol group; and a propylene oxide (PO) group or an ethylene oxide (EO) group.

[0017] Effects of the Invention

[0018] The water-in-oil emulsified skin cosmetic of the present invention, by virtue of the aforementioned technical features, exhibits significantly improved UV protection after contact with water, sweat, etc., compared to immediately after application of the cosmetic to the skin. Furthermore, the UV protection is significantly improved by the component (A) of the present invention, thereby reducing the amount of oil-phase thickeners conventionally added to improve UV protection. This results in a water-in-oil emulsified sunscreen cosmetic with a low stickiness and excellent feel during use. DETAILED DESCRIPTION

[0019] As described above, the water-in-oil emulsified skin cosmetic of the present invention (hereinafter sometimes simply referred to as "cosmetics") is characterized by:

[0020] It contains: (A) (a-1) copolymer and / or (a-2) silylated peptide, and (B) UV protection agent as essential components,

[0021] The (a-1) copolymer has: a silanol group; and a propylene oxide (PO) group or an ethylene oxide (EO) group.

[0022] The following is a detailed description of the components constituting the cosmetic of the present invention.

[0023] Component (A) of the present invention is at least one selected from (a-1) a copolymer having a silanol group and either a propylene oxide (PO) or an ethylene oxide (EO) group, and (a-2) a silylated peptide. The cosmetic product of the present invention may contain only one of (a-1) or (a-2), or both (a-1) and (a-2).

[0024] The copolymer (a-1) having a silanol group and a propylene oxide (PO) or ethylene oxide (EO) incorporated into the cosmetic of the present invention is a copolymer containing a polysiloxane structure and a polyoxyalkylene structure in the main chain of the polymer and having a trialkoxysilyl group or a silanol group in the side chain (hereinafter referred to as a "crosslinked silicone POA copolymer").

[0025] The polysiloxane structure constituting the main chain of the crosslinked siloxane POA copolymer (a-1) of the present invention is formed of polydialkylsiloxane, preferably polydimethylsiloxane, and a portion of the alkyl group (preferably methyl group) may be substituted with a phenyl group.

[0026] The polyoxyalkylene structure constituting the main chain of the crosslinked silicone POA copolymer (a-1) of the present invention preferably contains at least one selected from the group consisting of ethylene oxide (EO), propylene oxide (PO) and butylene oxide (BO) as a repeating unit.

[0027] The crosslinked silicone POA copolymer (a-1) in the present invention preferably further has a side chain formed of an organic group. Examples of the organic group forming the side chain include a hydrocarbon group (preferably an alkyl group, such as a linear or branched alkyl group having approximately 1 to 30 carbon atoms, or a phenyl group) that may be substituted with a substituent such as an amino group, a hydroxyl group, or a carboxyl group. The hydrocarbon group preferably has an amino group, and the hydrogen atoms of the amino group may be further substituted with an alkyl group or the like.

[0028] The (a-1) crosslinked silicone POA copolymer of the present invention preferably further contains a nitrogen atom in its main chain, and the side chain is preferably bonded to the nitrogen atom.

[0029] A more specific example of the crosslinked silicone POA copolymer (a-1) is Polysilicone-29 (INCI name). Polysilicone-29 is defined as a composite silicone compound obtained by reacting a dimethylsiloxane polymer having a terminal glycidoxypropyl group with PEG-13 diglycidyl ether, diethylaminopropylamine, and aminopropyltriisopropoxysilane.

[0030] As the (a-1) cross-linked silicone POA copolymer in the cosmetics of the present invention, commercially available products can be used. For example, "Silsoft CLX-E" (manufactured by Momentive Performance Materials) is preferably used. This copolymer belongs to the "Polysilicone-29" group. This copolymer has the following structure: a main chain comprising a polysiloxane structure, a polyoxyalkylene structure, and a nitrogen atom, and side chains containing trialkoxysilyl groups and side chains formed by organic groups. The polysiloxane structure comprises polydimethylsiloxane, the polyoxyalkylene structure comprises polyethylene oxide and polyisopropylene oxide, and the side chains are bonded to the nitrogen atoms of the main chain. "Silsoft CLX-E" is a commercial product comprising this copolymer, dipropylene glycol, and water.

[0031] As the (a-2) silylated peptide to be incorporated into the cosmetic of the present invention, it is preferable to use a silylated peptide represented by the general formula (I).

[0032]

[0033] [In formula (I), R 1 、R 2 、R 3 represents an alkyl group having 1 to 3 carbon atoms or a hydroxyl group, wherein R 1 、R 2 、R 3 They may all be the same or different. 4 represents a residue obtained by removing the terminal amino group of a basic amino acid having an amino group at the terminal of the side chain, R 5 Represents R 4 For amino acid side chains other than , a is 1 or 3, m is 0 to 200, n is 0 to 200, and m+n is 1 to 200. (M and n indicate only the number of amino acids, not the order of the amino acid sequence.)

[0034] The (a-2) silylated peptide represented by the general formula (I) can be obtained, for example, by condensing a silyl compound represented by the following general formula (II) with a peptide represented by the following general formula (III).

[0035]

[0036] [In formula (II), R 6 、R 7 、R 8 represents an alkyl group having 1 to 3 carbon atoms, an alkoxy group having 1 to 3 carbon atoms, a hydroxyl group or a halogen atom, wherein R 6 、R 7 、R 8 They may all be the same or different. a represents 1 or 3.]

[0037]

[0038] [In formula (III), R 4 represents a residue obtained by removing the terminal amino group of a basic amino acid having an amino group at the terminal of the side chain, R 5 Represents R 4 For amino acid side chains other than , m is 0 to 200, n is 0 to 200, and m+n is 1 to 200.]

[0039] In the silylated peptide (a-2) represented by the above general formula (I), R 4 It is a residue obtained by removing the terminal amino group from a basic amino acid having an amino group at the end of the side chain. Examples of the basic amino acid having an amino group at the end of the side chain include lysine, arginine, and hydroxylysine. 5 Represents R 4 Examples of such amino acids include glutamic acid, aspartic acid, alanine, serine, threonine, valine, methionine, leucine, isoleucine, tyrosine, phenylalanine, proline, and hydroxyproline.

[0040] The peptides represented by the general formula (III) include amino acids, peptides, and esters of amino acids or peptides. Examples of the amino acids include alanine, glycine, valine, leucine, isoleucine, proline, phenylalanine, tyrosine, serine, threonine, methionine, arginine, histidine, lysine, asparagine, aspartic acid, glutamine, glutamic acid, cystine, cysteine, cysteic acid, tryptophan, hydroxyproline, hydroxylysine, O-phosphoserine, and citrulline.

[0041] The peptides mentioned above are hydrolyzed peptides obtained by partially hydrolyzing natural peptides, synthetic peptides, or proteins using acids, bases, or enzymes. Examples of natural peptides include glutathione, bacitracin A, insulin, glucagon, oxytocin, and vasopressin. Examples of synthetic peptides include polyglycine, polylysine, polyglutamic acid, and polyserine. Hydrolyzed peptides are peptides obtained by partially hydrolyzing proteins using acids, bases, enzymes, or a combination thereof. Examples of protein sources include animal proteins, plant proteins, and proteins derived from microorganisms. Examples of animal proteins include silk, collagen (including gelatin as a denatured product thereof), keratin, fibronectin, sericin, casein, conchiolin, elastin, protamine, and egg yolk proteins and egg white proteins from chickens and the like. Examples of plant proteins include proteins contained in soybeans, wheat, rice (rice bran), sesame, peas, corn, and potatoes. Examples of proteins derived from microorganisms include yeast proteins isolated from yeasts of the genera Saccharomyces, Candida, and Pseudomonas, yeasts called brewer's yeast and sake yeast, and proteins isolated from mushrooms (basidiomycetes) and Chlorella.

[0042] Examples of the esters of the amino acids or peptides include esters of the carboxyl groups of the amino acids or peptides with hydrocarbon alcohols having 1 to 20 carbon atoms, such as methyl ester, ethyl ester, propyl ester, isopropyl ester, lauryl ester, cetyl ester, 2-ethylhexyl ester, 2-hexyldecyl ester, and stearyl ester.

[0043] More specific examples of the silylated peptide (a-2) include N-[2-hydroxy-3-(3-trihydroxysilyl)propoxy]propyl hydrolyzed protein and N-[2-hydroxy-3-(3-dihydroxymethylsilyl)propoxy]propyl hydrolyzed protein.

[0044] As the silylated peptide (a-2) in the cosmetic of the present invention, commercially available products can be used. Examples include "Promois S-700SIG," "Promois W-52SIG," and "Promois WS-HSIG" (all manufactured by Seiwa Chemicals Co., Ltd.), with "Promois S-700SIG" being preferred. "Promois S-700SIG" contains hydrolyzed silk PG-propylmethylsilanediol, 1,3-butylene glycol, methylparaben, propylparaben, and water.

[0045] The amount of ingredient (A) incorporated into the cosmetic of the present invention is not particularly limited, but is preferably 0.08 to 2% by mass, more preferably 0.15 to 1.5% by mass, relative to the total amount of the cosmetic, calculated based on the purity of ingredient (A). If the amount is less than 0.08% by mass, the effect of improving UV protection is insufficient, while if it exceeds 2% by mass, a sticky feeling tends to occur.

[0046] The (B) UV protection agent (hereinafter sometimes simply referred to as "ingredient (B)") added to the cosmetic of the present invention refers to a UV absorber and / or a UV scatterer, and UV protection agents commonly added to sunscreen cosmetics can be used.

[0047] Examples of ultraviolet absorbers include benzoic acid derivatives, salicylic acid derivatives, cinnamic acid derivatives, dibenzoylmethane derivatives, β,β-diphenylacrylate derivatives, benzophenone derivatives, benzyl camphor derivatives, phenylbenzimidazole derivatives, triazine derivatives, phenylbenzotriazole derivatives, anthracene derivatives, imidazoline derivatives, benzyl malonate derivatives, and 4,4-diarylbutadiene derivatives. Specific examples and trade names are listed below, but the invention is not limited thereto.

[0048] Examples of benzoic acid derivatives include p-aminobenzoic acid (PABA) ethyl ester, dihydroxypropyl PABA ethyl ester, dimethyl PABA ethylhexyl ester (e.g., "ESCALO 5 ETHYL HEXYL P25"; BASF), and diethylaminohydroxybenzoyl hexyl benzoate (e.g., "Uvinul A plus").

[0049] Examples of salicylic acid derivatives include homosalate ("Eusolex HMS"; Rona / EM Industries), ethylhexyl salicylate or octyl salicylate (e.g., "NeoHeliopan OS"; Haarmann and Reimer), dipropylene glycol salicylate (e.g., "Dipsal"; Scher), and TEA salicylate (e.g., "NeoHeliopan TS"; Haarmann and Reimer).

[0050] Examples of cinnamic acid derivatives include octyl methoxycinnamate or ethylhexyl methoxycinnamate (e.g., "PARSOL MCX"; F. Hoffmann-La Roche, Ltd.), isopropyl methoxycinnamate, isoamyl methoxycinnamate (e.g., "NeoHeliopan E1000"; Haarmann and Reimer), cinoxate, DEA methoxycinnamate, diisopropyl methylcinnamate, glyceryl-ethylhexanoate-dimethoxycinnamate, and di-(2-ethylhexyl)-4'-methoxybenzylidenemalonate.

[0051] Examples of the dibenzoylmethane derivative include 4-tert-butyl-4′-methoxydibenzoylmethane (for example, “PARSOL 1789”).

[0052] Examples of the β,β-diphenylacrylate derivative include octocrylene (for example, "Uvinul N539T"; BASF Corporation) and the like.

[0053] Examples of benzophenone derivatives include benzophenone-1 (e.g., "Uvinul 400"; BASF), benzophenone-2 (e.g., "Uvinul D50"; BASF), benzophenone-3 or benzophenone (e.g., "Uvinul M40"; BASF), benzophenone-4 (e.g., "Uvinul MS40"; BASF), benzophenone-5, benzophenone-6 (e.g., "Helisorb 11"; Norquay), benzophenone-8 (e.g., "Spectra-Sorb UV-24"; American Cyanamid Co.), benzophenone-9 (e.g., "Uvinul DS-49"; BASF), and benzophenone-12.

[0054] Examples of benzyl camphor derivatives include 3-benzylidene camphor (e.g., "Mexoryl SD"; Sysmex Corporation), 4-methylbenzylidene camphor, benzylidene camphorsulfonic acid (e.g., "Mexoryl SL"; Sysmex Corporation), camphorbenzalkonium methylsulfate (e.g., "Mexoryl SO"; Sysmex Corporation), terephthalylidene dicamphorsulfonic acid (e.g., "Mexoryl SX"; Sysmex Corporation), and polyacrylamidomethylbenzylidene camphor (e.g., "Mexoryl SW"; Sysmex Corporation).

[0055] Examples of the phenylbenzimidazole derivative include phenylbenzimidazole sulfonic acid (e.g., "Eusolex 232"; Merck Ltd.), disodium phenyldibenzimidazole tetrasulfonate (e.g., "NeoHeliopan AP"; Haarmann and Reimer), and the like.

[0056] Examples of the triazine derivative include bis-ethylhexyloxyphenol methoxyphenyl triazine (e.g., "Tinosorb S"; Ciba Specialty Chemicals Inc.), ethylhexyl triazone (e.g., "Uvinul T150"; BASF), diethylhexyl butyramido triazone (e.g., "Uvasorb HEB"; SIGMA 3V), 2,4,6-tris(diisobutyl-4'-aminobenzylidenemalonate)-s-triazine, and 2,4,6-tris[4-(2-ethylhexyloxycarbonyl)anilino]-1,3,5-triazine.

[0057] Examples of the phenylbenzotriazole derivative include drometrizole trisiloxane (for example, "Silatrizole" manufactured by Rhodia Chimie Co., Ltd.), methylenebis(benzotriazolyltetramethylbutylphenol) (for example, "Tinosorb M" manufactured by Ciba Specialty Chemicals Inc.), and the like.

[0058] Examples of the anthracenyl derivative include menthyl anthranilate (for example, "NeoHeliopan MA" manufactured by Haarmann and Reimer).

[0059] Examples of the imidazoline derivative include ethylhexyldimethoxybenzylidene-dioxoimidazolinium propionate.

[0060] Examples of the benzalmalonate derivative include polyorganosiloxane having a benzalmalonate functional group (for example, polysilicone-15; "PARSOL SLX"; DSM Nutrition Japan KK).

[0061] Examples of the 4,4-diallylbutadiene derivative include 1,1-dicarboxy(2,2′-dimethylpropyl)-4,4-diphenylbutadiene and the like.

[0062] The ultraviolet scattering agent used in the present invention is not particularly limited. Specific examples include fine particle metal oxides such as zinc oxide, titanium oxide, iron oxide, cerium oxide, and tungsten oxide.

[0063] The ultraviolet scattering agent may be surface-treated or may be subjected to various hydrophobic surface treatments, but it is preferred to use an ultraviolet scattering agent subjected to a hydrophobic surface treatment. The surface treatment agent is not particularly limited, and surface treatment agents commonly used in the cosmetic field can be used, for example, siloxanes such as polydimethylsiloxane and alkyl-modified siloxanes, alkoxysilanes such as octyltriethoxysilane, dextrin fatty acid esters such as dextrin palmitate, and fatty acids such as stearic acid.

[0064] The component (B) in the present invention includes an embodiment containing only an ultraviolet absorber, an embodiment containing only an ultraviolet scattering agent, and an embodiment containing both an ultraviolet absorber and an ultraviolet scattering agent.

[0065] The amount of ingredient (B) incorporated into the cosmetic of the present invention is not particularly limited, but is preferably 5 to 40% by mass, more preferably 10 to 30% by mass, and even more preferably 10 to 20% by mass, relative to the total amount of the cosmetic. If the amount of ingredient (B) incorporated is less than 5% by mass, a sufficient UV protection effect may not be achieved. Even if the amount of ingredient (B) incorporated exceeds 40% by mass, an increase in UV protection effect commensurate with the amount incorporated cannot be expected, and emulsion stability may be deteriorated, which is undesirable.

[0066] The cosmetics of the present invention having the above-mentioned technical features have the characteristic that the UV protection effect (absorbance) is improved when in contact with water. "The UV protection effect (absorbance) is improved by contact with water" can be roughly defined as follows. A specified amount of a sample of an emulsified cosmetic is dropped onto a measuring plate, applied to a specified area, and dried to form a coating film. The absorbance of the coating film is measured by a spectrophotometer or the like, and the absorbance of a coating film of a substance that does not absorb UV rays (such as glycerin) is used as a reference, and the absorbance of the coating film (before water bath) is used as the cumulative absorbance value (Abs before ).

[0067] Next, the measuring plate with the coating film formed thereon was immersed in water under predetermined conditions, and the absorbance integrated value (Abs after ).

[0068] The rate of change in absorbance before and after the water bath (Abs change rate) was calculated according to the following formula.

[0069] Abs change rate (%) = [(Abs after ) / (Abs before )]×100

[0070] When the Abs change rate exceeds 100%, it is defined as a case where the UV protection effect has improved.

[0071] In the cosmetic of the present invention, the Abs change rate is at least greater than 100%, preferably 105% or greater, more preferably 110% or greater, further preferably 115% or greater, and particularly preferably 120% or greater.

[0072] To further enhance the UV protection effect, the cosmetic of the present invention may further include an oil phase thickener (C) (hereinafter sometimes simply referred to as "ingredient (C)") in addition to ingredients (A) and (B). The addition of ingredient (C) synergistically improves the UV protection provided by ingredient (A) of the present invention.

[0073] Ingredient (C) used in the cosmetics of the present invention is not particularly limited and can be appropriately selected from ingredients used in emulsified cosmetics, etc., that thicken the oil phase by dissolving in the oil component or swelling with the oil component. Specific examples include dextrin fatty acid esters such as dextrin palmitate and dextrin myristate; sucrose fatty acid esters such as sucrose caprylate; higher fatty acids having 8 to 22 carbon atoms that are solid at room temperature, such as lauric acid, myristic acid, palmitic acid, and stearic acid, or their salts; and organically modified clay minerals such as disteardimethylammonium hectorite and benzyldimethylstearylammonium hectorite. Among these, it is preferred to use any one of organically modified clay minerals, dextrin fatty acid esters, and sucrose fatty acid esters, or a combination of two or more.

[0074] The amount of component (C) in the cosmetic of the present invention is not particularly limited, but is preferably 0.1 to 3% by mass, more preferably 0.3 to 1% by mass, relative to the total amount of the cosmetic. A higher amount of component (C) tends to produce a stickier feel.

[0075] The cosmetic of the present invention contains, in addition to the above-mentioned ingredients, oil and water constituting a water-in-oil emulsified skin cosmetic, and optionally a surfactant (emulsifier).

[0076] The surfactant used in the cosmetic of the present invention is not particularly limited as long as it is a surfactant commonly used in water-in-oil emulsified cosmetics. From the perspective of feel during use, a surfactant having a siloxane skeleton (polysiloxane structure) and an HLB of less than 8 is preferred. For example, polyether-modified silicones, polyether-alkyl co-modified silicones, polyglycerol-modified silicones, and / or polyglycerol-alkyl co-modified silicones are preferably used, with polyether-modified silicones and polyether-alkyl-modified silicones being more preferred.

[0077] The amount of the surfactant blended is not particularly limited, but is preferably 0.1 to 10% by mass, more preferably 0.5 to 5% by mass, relative to the total amount of the cosmetic.

[0078] The oil component used in the cosmetic of the present invention is not particularly limited, and examples thereof include liquid oils such as avocado oil, camellia seed oil, macadamia nut oil, mink oil, olive oil, castor oil, jojoba oil, triglycerol, and tricaprylin; hydrocarbon oils such as liquid paraffin, squalane, paraffin, ceresin, and squalene; lauric acid, myristic acid, palmitic acid, stearic acid, behenic acid, oleic acid, 12-hydroxystearic acid, isostearic acid, linoleic acid, and linoleic acid. acid) and other higher fatty acids; lauryl alcohol, cetyl alcohol, stearyl alcohol, behenyl alcohol, oleyl alcohol, monostearyl glyceryl ether, monopalmityl glyceryl ether, cholesterol, phytosterol, isostearyl alcohol and other higher alcohols; isononyl isononanoate, isopropyl myristate, cetyl octanoate, octyldodecyl myristate, butyl stearate, decyl oleate, glycol dioctanoate, diisostearyl malate, trimethylolpropane trioctanoate, trimethylolpropane triisostearate Ester oils such as alkyl esters, pentaerythritol tetraoctanoate, tricaprylin, triisostearin, ethyl acetate, butyl acetate, and amyl acetate; linear silicone oils such as dimethylpolysiloxane, methylphenylpolysiloxane, methylhydrogenpolysiloxane, and diphenylsiloxyphenyltrimethicone; and cyclic silicone oils such as decamethylcyclopentasiloxane, dodecamethylcyclohexasiloxane, and octamethylcyclotetrasiloxane can be used alone or in combination. From the perspective of feel during use, silicone oil is preferred as the oil component.

[0079] The amount of the oil component is not particularly limited, but is preferably 10-70% by mass, more preferably 15-70% by mass, and even more preferably 20-70% by mass relative to the total amount of the cosmetic. The inclusion of the oil component within the above range allows for good spreadability, excellent water resistance, and superior feel during use.

[0080] Deionized water or purified water is preferably used as the water used in the cosmetic of the present invention. The water content is appropriately determined and is preferably 1 to 30% by mass relative to the total amount of the cosmetic.

[0081] In addition to the above-mentioned ingredients, the cosmetics of the present invention may contain, as needed, ingredients commonly used in cosmetics, such as moisturizers, film-forming agents, aqueous phase thickeners, alcohols, chelating agents, colorants, pigments, pearlescent agents, antioxidants, fragrances, various medicinal ingredients, and preservatives.

[0082] The cosmetics of the present invention can be produced according to conventional methods for producing water-in-oil emulsions. For example, after separately preparing the aqueous phase and oil phase components, these aqueous and oil phases are mixed and emulsified using a homomixer or the like to obtain the water-in-oil emulsified skin cosmetics of the present invention.

[0083] The specific dosage form of the cosmetic of the present invention is not particularly limited, and may be a lotion, emulsion, cream, lotion, spray, etc. that exhibits improved sun protection after a bath. The cosmetic of the present invention can be produced using conventional methods suitable for each dosage form.

[0084] Example

[0085] The present invention is described in more detail below with reference to the following examples, but the present invention is not limited thereto. The amounts of ingredients are expressed as mass % relative to the total amount of the cosmetic unless otherwise specified. Before describing each example in detail, the evaluation methods employed are described.

[0086] <Ultraviolet protection improvement effect>

[0087] On a measurement plate (S plate) (5×5 cm V-grooved PMMA plate, SPF MASTER-PA01), the concentration of 2 mg / cm 2 The cosmetic product (sample) of each example was added dropwise, applied with a fingertip for 60 seconds, and dried for 15 minutes. The absorbance of the resulting coating was then measured using a U-3500 self-recording spectrophotometer manufactured by Hitachi, Ltd. Using glycerin, which does not absorb ultraviolet light, as a control, the absorbance (Abs) was calculated using the following formula. The measured values ​​at 280 nm to 400 nm were integrated to determine the cumulative absorbance value.

[0088] Abs=-log(T / To)

[0089] T: transmittance of the sample, To: transmittance of glycerol

[0090] The plate to be measured was thoroughly immersed in water with a hardness of 50 to 500 and stirred in the water for 30 minutes (using a 3-1 motor at 300 rpm). It was then dried for approximately 15 to 30 minutes until the water droplets on the surface disappeared. The absorbance was measured again and the integrated absorbance value was calculated in the same manner as above.

[0091] Next, the Abs change rate was calculated from the Abs cumulative values ​​before and after the water bath (the following formula) as an indicator of the improvement effect of the ultraviolet protection ability.

[0092] UV protection improvement effect:

[0093] Abs change rate (%) = [(Abs after ) / (Abs before )]×100

[0094] User experience

[0095] Ten panelists actually used each sample, and sensory evaluation was conducted on a four-level scale based on the following evaluation criteria regarding the feeling during use (no stickiness).

[0096] Evaluation Benchmarks

[0097] A: There is no stickiness at all compared to the control.

[0098] B: No stickiness compared to the control.

[0099] C: There was a sticky feeling equivalent to that of the control.

[0100] D: There is a sticky feeling compared with the control.

[0101] <Examples 1 and 2 and Comparative Example 1>

[0102] A water-in-oil emulsified skin cosmetic having the composition shown in Table 1 below was prepared according to a conventional method. The UV protection improvement effect was evaluated according to the above-mentioned evaluation method. The results are summarized in the table.

[0103] [Table 1]

[0104]

[0105] As shown in Table 1, when the component (A) of the present invention is not added to the cosmetic product without an oil phase thickener (Comparative Example 1), the UV protection effect is reduced by water bathing. In contrast, when the component (A) of the present invention is added (Examples 1 and 2), the UV protection ability after water bathing is significantly improved.

[0106] <Examples 3 to 6 and Comparative Example 2>

[0107] Water-in-oil emulsified skin cosmetics having the compositions shown in Table 2 below were prepared using conventional methods. The UV protection improvement effect and feel during use were evaluated using the aforementioned evaluation methods. Comparative Example 2 was used as a control for the feel during use evaluation. The results are summarized in the table.

[0108] [Table 2]

[0109]

[0110] As shown in Table 2, Comparative Example 2 (control) exhibits an effect of improving UV protection after a water bath due to the addition of disteardimethylammonium hectorite, listed in Patent Document 1 as an ingredient that exhibits an effect of improving UV protection after a water bath. On the other hand, when disteardimethylammonium hectorite, which is a component of the present invention (A), is added (Examples 3-6), the effect of improving UV protection after a water bath is greater than that of Comparative Example 2. Furthermore, the stickiness is suppressed compared to Comparative Example 2, resulting in an extremely favorable feel during use.

[0111] <Example 7 and Comparative Example 3>

[0112] Water-in-oil emulsified skin cosmetics having the compositions shown in Table 3 below were prepared by conventional methods. The UV protection improvement effect was evaluated according to the above-mentioned evaluation method. The results are summarized in the table.

[0113] [Table 3]

[0114]

[0115] The effect of combining the present invention's component (A) and the oil phase thickener (component (C)) (Example 7) on improving UV protection after a water bath was compared with the effect of combining the present invention's component (A) alone (Example 1) and the effect of combining the component (C) alone (Comparative Example 3). The results shown in Table 3 demonstrate that the enhanced effect of improving UV protection after a water bath achieved by combining the components (A) and (C) is synergistic.

Claims

1. A water-in-oil emulsified skin cosmetic comprising: (A) polysilicone-29, (B) a UV protection agent, and (C) an oil phase thickener. The component (A) is mixed in the form of an aqueous solution. The blending amount of the above-mentioned component (A) is 0.08 to 2% by mass. The (C) oil phase thickener contains one or more selected from the group consisting of organically modified clay minerals, dextrin fatty acid esters, and sucrose fatty acid esters.

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