Oil-in-water sunscreen cosmetic

Abstract

The object of this invention is to provide a water-in-oil emulsion sunscreen cosmetic, wherein the water-in-oil emulsion composition containing vesicles exhibits excellent vibration stability and water resistance, and possesses high UV protection capability. The water-in-oil emulsion sunscreen cosmetic of this invention is characterized by comprising: (A) an aqueous component selected from monohydric alcohols and dihydric alcohols, (B) a polyoxyalkylene-modified silicone, (C) an oil component containing a polar oil, (D) a UV scattering agent having a hydrophobic surface, and (E) an anionic surfactant. When the aforementioned aqueous component (A) is a monohydric alcohol alone, its content is 1-15% by mass relative to the total amount of the cosmetic; when the aforementioned aqueous component (A) is a dihydric alcohol alone, its content is 1-20% by mass relative to the total amount of the cosmetic; when the aforementioned aqueous component (A) is a combination of monohydric alcohols and dihydric alcohols, its total content is 1-45% by mass relative to the total amount of the cosmetic; and when the aforementioned oil component (C) is combined with a low-molecular-weight oil component, the proportion of the low-molecular-weight oil component, by mass, is 50% or less relative to the total amount of oil components other than UV absorbers.

Description

Technical Field

[0001] This invention relates to water-in-oil type sunscreens with improved vibration stability and water resistance. Background Technology

[0002] Among amphiphilic substances, there are those that form spherical closed bodies composed of dipole membranes (lamellar liquid crystals) in the aqueous phase; these dipole membrane closed bodies are called vesicles. Vesicles can retain water-soluble components inside the closed body and oil-soluble components inside the dipole membrane, and are expected to improve the stability of the system, thus they are used as bases in cosmetics.

[0003] For example, Patent Documents 1 and 2 disclose that specific polyoxyethylene hydrogenated castor oil derivatives are used as amphiphilic substances to form vesicles, which are then contained as emulsifiers, thereby obtaining non-sticky cosmetics with a good user experience.

[0004] In addition, organosilicone surfactants can be cited as amphiphilic substances for forming vesicles. Vesicles formed by organosilicone surfactants can produce non-sticky compositions with a good user experience and are easy to prepare, so they are preferred.

[0005] For example, Patent Document 3 describes adding a water-soluble low-molecular-weight surfactant to a vesicle-containing aqueous solution formed by pre-mixing an aqueous formulation and an organosilicon surfactant, thereby improving the stability of the vesicles. Furthermore, Patent Document 4 describes adding an anionic surfactant after vesicles are formed from organosilicon surfactants, thereby improving the stability of the vesicles.

[0006] However, these vesicles formed by organosilicon surfactants are mainly used in solubilizing solutions with low oil content, and there are no examples of their use in emulsion compositions. In fact, Patent Document 4 shows that if the oil content is set to 0.4% by mass or more, there is a tendency for decreased stability.

[0007] Patent document 5 discloses a technique for dispersing a water-insoluble liquid phase into an external phase using vesicles containing an internal phase. However, vesicle emulsification is not stable and has practical limitations. Therefore, there is a tendency for the amount of vesicles involved to increase, which, as is generally known, can sometimes lead to stickiness due to the surfactants that form the vesicles.

[0008] Existing technical documents

[0009] Patent documents

[0010] Patent Document 1: International Publication No. 2010-064678

[0011] Patent Document 2: Japanese Patent Application Publication No. 2011-195509

[0012] Patent Document 3: Japanese Patent Application Publication No. 2008-024681

[0013] Patent Document 4: Japanese Patent Application Publication No. 2012-092084

[0014] Patent Document 5: Japanese Patent No. 3137592 Summary of the Invention

[0015] The problem the invention aims to solve

[0016] The purpose of this invention is to provide a water-in-oil emulsion sunscreen cosmetic with excellent stability and water resistance and high UV protection capability.

[0017] Solution for solving the problem

[0018] In order to solve the above-mentioned problems, the inventors conducted repeated in-depth research and found that in the presence of specific aqueous components, vesicles formed by specific organosilicon surfactants are emulsified by organosilicon nanodisks used as precursors, and the oil components in the oil phase are limited to specific oil components, thereby significantly improving vibration stability and water resistance. Thus, the present invention was completed.

[0019] Here, "nanopan" refers to a planar laminar liquid crystal block formed from vesicles (laminar liquid crystal spherical blocks) of amphiphilic substances as a precursor, which does not encapsulate water-soluble components inside the block and has lipophilic groups at the edges. The nanodisc exists as a vesicle in an oil-free composition, and its structure is transformed into a nanodisc by emulsification with added oil (hereinafter also referred to as "transfer"). The nanodisc of the present invention can be obtained by adding an anionic surfactant and oil to a vesicle aqueous dispersion containing an aqueous component selected from monohydric and dihydric alcohols and polyoxyalkylene-modified organosilicon to form vesicles, and dispersing under strong stirring. The nanodisc exists in an emulsified state adsorbed at the oil-water interface, which contributes to emulsion stability. In this specification, the amphiphilic substance forming the vesicles is an organosilicon surfactant; therefore, the nanodisc of the present invention is also referred to as an "organosilicon nanodisc."

[0020] That is, the present invention provides a water-in-oil type sunscreen cosmetic, which comprises:

[0021] (A) Aqueous components selected from monohydric alcohols and dihydric alcohols,

[0022] (B) Polyoxyalkylene-modified organosilicon,

[0023] (C) Oils containing polar oils,

[0024] (D) Ultraviolet scattering agents with hydrophobic surfaces, and

[0025] (E) Anionic surfactants,

[0026] When the aqueous component (A) is a monohydric alcohol alone, it accounts for 1 to 15% by mass relative to the total amount of the cosmetic; when the aqueous component (A) is a dihydric alcohol alone, it accounts for 1 to 20% by mass relative to the total amount of the cosmetic; when the aqueous component (A) is a combination of monohydric and dihydric alcohols, its total amount accounts for 1 to 45% by mass relative to the total amount of the cosmetic.

[0027] When low-molecular-weight oil is incorporated as the oil component described in (C), the proportion of low-molecular-weight oil, by mass ratio, is 50% or less relative to the total amount of oil, excluding the UV absorber.

[0028] In addition, the water-in-oil emulsion cosmetic of the present invention is characterized in that the nanodiscs formed by the aforementioned (B) polyoxyalkylene modified organosilicon are attached to the oil-water interface.

[0029] The effects of the invention

[0030] The cosmetic of the present invention has the above-described structure, thus becoming a water-in-oil emulsion with high emulsifying power. Therefore, a greater amount of UV-protective agents (UV absorbers and UV scatterers) can be incorporated into the oil phase. Furthermore, compared to conventional vesicle emulsification, vibration stability and water resistance can be improved. This results in a more portable cosmetic. Moreover, the organosilicon nanodiscs of the present invention possess sufficient emulsifying power, thus enabling the incorporation of water-soluble agents such as salt-type whitening agents, whose stability typically deteriorates when incorporated into the aqueous phase of the external phase. Detailed Implementation

[0031] The cosmetic of the present invention is characterized in that it comprises: (A) an aqueous component selected from monohydric alcohols and dihydric alcohols, (B) a polyoxyalkylene-modified silicone, (C) an oil component containing a polar oil, (D) an ultraviolet scattering agent having a hydrophobic surface, and (E) an anionic surfactant. The components constituting the cosmetic of the present invention will be described in detail below.

[0032] <(A) Water-based ingredients>

[0033] The aqueous component (A) in the cosmetic of the present invention (hereinafter sometimes simply referred to as "(A) component") refers to one or more selected from monohydric alcohols and dihydric alcohols.

[0034] As a monohydric alcohol, there is no particular limitation as long as it is commonly used in cosmetics. Examples include ethanol, n-propanol, and isopropanol. In this invention, ethanol is preferred.

[0035] As a diol, there are no particular limitations as long as it is used by ordinary users in cosmetics. Examples include 1,3-butanediol and dipropylene glycol. In this invention, dipropylene glycol is preferred.

[0036] The surface of spherical vesicles formed by surfactants is entirely covered with hydrophilic groups, but nanodiscs have lipophilic groups at their edges, making it difficult to generate nanodiscs in water. If monohydric and dihydric alcohols are present in water, the surfactant (in this invention, polyether-modified organosilicon) is hydrophilized through a solvent effect, thereby promoting the transfer from spherical vesicles to nanodiscs.

[0037] On the other hand, when polyoxyalkylene modified organosilicones such as PEG-12 polydimethylsiloxane are dissolved in alcohol, triols such as glycerol and polyols such as sorbitol tend to hinder the transfer of surfactants to nanodiscs by making them lipophilic. Therefore, when combined with alcohols of three or more, it is desirable that the total amount of monools and diols be greater than the total amount of polyols of three or more.

[0038] When a monohydric alcohol is used alone, its amount is 1 to 15% by mass relative to the total amount of the cosmetic product; when a dihydric alcohol is used alone, its amount is 1 to 20% by mass relative to the total amount of the cosmetic product. Furthermore, when a monohydric alcohol and a dihydric alcohol are used in combination, their total amount is 1 to 45% by mass relative to the total amount of the cosmetic product, preferably 1 to 35% by mass. Preferably, the concentrations of the monohydric alcohol and the dihydric alcohol satisfying the following formula (1) are used as an upper limit.

[0039] Monohydric alcohol concentration in aqueous phase (%) / 15 + Dihydric alcohol concentration in aqueous phase (mass%) / 20 ≤ 1 (1)

[0040] When the amount of monohydric alcohol alone, the amount of dihydric alcohol alone, or the total amount of monohydric alcohol and dihydric alcohol is less than 1% by mass, vesicles may not form or may have disordered structures, resulting in failure to emulsify. In addition, when the amount of monohydric alcohol alone exceeds 15% by mass, the amount of dihydric alcohol alone exceeds 20% by mass, and the ratio of monohydric alcohol to dihydric alcohol is outside the range of the above formula (1), or even if the total amount exceeds 45% by mass within the range of the above formula (1), the vesicle membrane may become too soft or the vesicles may migrate to micelles, resulting in failure to achieve a stabilization effect.

[0041] <(B) Polyoxyalkylene-modified organosilicon>

[0042] The (B) polyoxyalkylene-modified organosilicon (hereinafter sometimes simply referred to as "(B) component") incorporated in the cosmetic of the present invention is a surfactant having a polysiloxane structure as a hydrophobic group and a polyoxyalkylene structure as a hydrophilic group. Preferably, it is a water-soluble organosilicon surfactant formed by replacing a portion of the methyl group of polydimethylsiloxane with polyethylene glycol. Specifically, it is represented by the following formula (2).

[0043]

[0044] In the aforementioned equation (2), R 1 It is a hydrogen or an alkyl group having 1 to 6 carbon atoms, and they may be the same or different individually. At least one of A is a polyoxyalkylene group represented by formula (3):

[0045] -(CH2)a-(C2H4O)b-(C3H6O)cR 2 (3)

[0046] The other A's are hydrogen atoms or alkyl groups having 1 to 6 carbon atoms; they may be the same or different on their own. R in formula (3) 2 It is a hydrogen or an alkyl group having 1 to 6 carbon atoms, where a is 1 to 6, b is 0 to 50, c is an integer from 0 to 50, and b+c is at least 5. In the aforementioned formula (2), m is an integer from 1 to 200, and n is an integer from 0 to 50.

[0047] As the (B) polyoxyalkylene-modified organosilicon of the present invention, the HLB in the HLB calculation based on Griffith's formula is preferably less than 10.

[0048] In the cosmetic of the present invention, (B) the polyoxyalkylene modified organosilicon is particularly preferably PEG-12 polydimethylsiloxane with c=0 and b=12 in the aforementioned formula (3). Furthermore, PEG-12 polydimethylsiloxane is further preferably HLB less than 10.

[0049] Commercially available products of PEG-12 polydimethylsiloxane include DOWSIL™ ES-5373, SH3772M, SH3773M, SH3775M (all manufactured by Dow Toray Co., Ltd.), and IM-22 (manufactured by Wacker Chemical Corp.).

[0050] (B) The amount of the ingredient is not particularly limited as long as it can form vesicles as precursors to nanodiscs. For example, it is 0.1 to 5.0% by mass relative to the total amount of cosmetic, preferably 0.3 to 3.0% by mass, and even more preferably 0.8 to 2.0% by mass. When the amount is less than 0.1% by mass, vesicles may not form sufficiently, and when it exceeds 5.0% by mass, the stability of the vesicles may be poor.

[0051] The cosmetic of the present invention contains nanodiscs formed by a surfactant of component (B). Vesicles, which are precursors to the nanodiscs, can be formed using conventional methods. Specifically, vesicles formed by component (B) can be formed by mixing and stirring an aqueous component (A) and a polyoxyalkylene-modified organosilicon (B). When forming vesicles, water, in addition to the aqueous component (A), and other aqueous components commonly used in cosmetics can be added in amounts that do not impair the stability of the vesicles. It should be noted that the average particle size of the vesicles is not particularly limited, but is typically about 30 nm to 150 nm.

[0052] <(C) Oil content>

[0053] The (C) oil component (hereinafter sometimes simply referred to as "(C) component") incorporated in the cosmetics of the present invention refers to an oil component that must contain at least a polar oil. Wherein, when the (C) oil component of the present invention incorporates a low-molecular-weight oil component, the proportion of the low-molecular-weight oil component, relative to the total amount of oil component excluding ultraviolet absorbers, must be 50% or less by mass.

[0054] Examples of polar oils used in the cosmetics of the present invention include ester oils, particularly ester oils with an IOB value of about 0.1 to 0.6, and oil-soluble polar ultraviolet absorbers.

[0055] Specific examples of ester oils with an IOB value of approximately 0.1 to 0.6 are not limited and can include diisopropyl sebacate, pentaerythritol tetra(ethylhexanoate), cetyl ethylhexanoate, jojoba oil, phytosterol / octyldodecyl lauroyl glutamate, triisostearin, glyceryl diisostearate, glyceryl tri(ethylhexanoate), phytosterol / behenol dimer linoleate, phytosterol / isostearol / cetearol / stearyl / behenol dimer linoleate, isopropyl palmitate, phytosterol macadamia oleate, pentaerythritol tetra(behenic acid / benzoic acid / ethylhexanoate), ethylhexyl palmitate, myristyl myristate, isopropyl myristate, tripropylene glycol diheptyl oleate, isodecanyl neopentanoate, etc.

[0056] Specific examples of oil-soluble polar ultraviolet absorbers include those commonly used in sunscreen cosmetics, without particular limitation. Specific examples include ethylhexyl methoxycinnamate, octocrylene, benzylmalonate polysiloxane, polysiloxane-15, tert-butylmethoxydibenzoylmethane, ethylhexyl triazine, diethylaminohydroxybenzoyl benzoate, bis-ethylhexyloxyphenol methoxyphenyl triazine, benzophenone-3, methylene bis-benzotriazolyl tetramethylbutylphenol, phenylbenzimidazole sulfonic acid, humosasulfate, ethylhexyl salicylate, dimethyl camphor sulfonic acid, cresoltrazolium trisiloxane, and other organic ultraviolet absorbers.

[0057] As the polar oil used in this invention, one or more types can be used in combination.

[0058] In the oil fraction (C) of the present invention, in addition to the above-mentioned polar oil, one or more types selected from hydrocarbon oil and silicone oil may be added.

[0059] Specific examples of hydrocarbon oils include isododecane, isohexadecane, hydrogenated polydecene, isoparaffins, liquid paraffin, terrestrial paraffin, squalane, squalane, paraffin wax, pure terrestrial wax, squalene, petrolatum, and microcrystalline wax.

[0060] Specific examples of silicone oils include chain polysiloxanes (e.g., dimethyl polysiloxane, methylphenyl polysiloxane, diphenyl polysiloxane, etc.), cyclic polysiloxanes (e.g., octamethylcyclotetrasiloxane, decamethylcyclopentasiloxane, dodecylcyclohexasiloxane, etc.), organosilicon resins forming a three-dimensional network structure, silicone rubber, various modified polysiloxanes (amino-modified polysiloxanes, polyether-modified polysiloxanes, alkyl-modified polysiloxanes, fluorinated polysiloxanes, etc.), and acrylic organosilicones.

[0061] In the cosmetics of this invention, when low-molecular-weight oils are incorporated into the oil component, the proportion of low-molecular-weight oils, by mass ratio, must be 50% or less relative to the total amount of oils other than UV absorbers. This is because sufficient vibrational stability cannot be obtained when the proportion of low-molecular-weight oils relative to the total amount of oils other than UV absorbers exceeds 50%. It should be noted that in the cosmetics of this invention, low-molecular-weight oils may not be incorporated as an oil component; therefore, the lower limit for the proportion of low-molecular-weight oils relative to the total amount of oils other than UV absorbers is 0%.

[0062] In this invention, low-molecular-weight oil refers to oil with a evaporation rate of 30% or more per hour at 25°C. Here, evaporation rate refers to the rate of change of weight per hour measured by gravimetric method at 25°C with approximately 0.2g of sample added to a glass dish with filter paper placed on it. Specific examples of low-molecular-weight oils include isododecane and low-viscosity volatile organosilicones (low-viscosity polydimethylsiloxane) with an average degree of polymerization below 650. Commercially available low-molecular-weight oils include Creasil IDCG (manufactured by Shima Trading Co., Ltd.) and KF-96L-1.5CS (manufactured by Shin-Etsu Chemical Co., Ltd.). Creasil IDCG has an evaporation rate of over 90%, while KF-96L-1.5CS has an evaporation rate of approximately 50%.

[0063] As the oil component (C) of the present invention, it may contain at least a polar oil. Therefore, the cosmetics of the present invention include those that contain only polar oils as oil components.

[0064] The amount of oil (C) incorporated in the cosmetic of the present invention is not particularly limited as long as it is the amount commonly used when incorporating a UV scattering agent in the oil phase. For example, it can be 1 to 40% by mass relative to the total amount of the cosmetic. When the amount of oil (C) exceeds 40% by mass, there is a tendency for decreased stability and usability. When a UV absorber is incorporated, from the viewpoint of obtaining sufficient UV protection effect from the UV absorber, it is preferably 1% by mass or more, more preferably 3 to 30% by mass or 5 to 25% by mass relative to the total amount of the cosmetic.

[0065] <(D) Ultraviolet Scattering Agent>

[0066] The (D) ultraviolet scattering agent (hereinafter sometimes simply referred to as "(D) ingredient") incorporated into the cosmetics of the present invention is not particularly limited and can be suitably selected from those commonly used in cosmetics. Specific examples include metal oxides such as titanium oxide, zinc oxide, iron oxide, cerium oxide, and tungsten oxide. In the present invention, titanium oxide and zinc oxide are preferred.

[0067] The (D) ultraviolet scattering agent used in this invention only requires that the particle surface be hydrophobic; it can be either untreated or hydrophobically treated. Various hydrophobic surface treatments can be used to achieve surface hydrophobicity. Examples of hydrophobic surface treatments include: organosilicon treatment using silicone oils such as methylhydropolysiloxane, dimethylpolysiloxane, and methylphenylpolysiloxane; alkylsilanes such as methyltrimethoxysilane, ethyltrimethoxysilane, hexyltrimethoxysilane, and octyltrimethoxysilane; fluoroalkylsilanes such as trifluoromethylethyltrimethoxysilane and heptadecafluorodecyltrimethoxysilane; fluorinated alkylsilanes such as perfluoroalkyl phosphates and perfluoroalcohols; amino acid treatment using N-acylglutamic acid, N-acylaspartic acid, and N-acyllysine; lecithin treatment; metal soap treatment; fatty acid treatment; and alkyl phosphate treatment.

[0068] (D) There is no particular limitation on the amount of ingredient, but it is usually more than 1% by mass relative to the total amount of cosmetics, for example, 1 to 30% by mass, preferably 1 to 20% by mass. When the amount is less than 1% by mass, it is difficult to obtain sufficient UV protection effect, and when it exceeds 30% by mass, there is a tendency for the stability to deteriorate.

[0069] The cosmetic of the present invention exhibits excellent emulsification stability, thus enabling the formulation of more than 10% by mass of ultraviolet scattering agents.

[0070] The cosmetic of the present invention is a water-in-oil powder composition in which an ultraviolet scattering agent is dispersed in oil droplets as an internal phase (D).

[0071] In the cosmetic of the present invention, the oil phase is preferably 1 to 50% by mass relative to the total amount of the cosmetic.

[0072] <(E) Anionic surfactants>

[0073] The (E) anionic surfactant (hereinafter sometimes simply referred to as "(E) ingredient") incorporated into the cosmetic of the present invention can be any surfactant commonly used in cosmetics, and is a surfactant with anionic hydrophilic groups, such as those with carboxylic acid, sulfonic acid, or phosphoric acid structures, other than the aforementioned (B) polyoxyalkylene modified organosilicon surfactant. The nanodiscs are stabilized by the incorporation of the anionic surfactant.

[0074] Anionic surfactants with a Krafft point above room temperature are preferred. When the Krafft point of anionic surfactants is below room temperature, silicone-based surfactants and anionic surfactants are easily mixed and interact, thus tending to hinder the transfer from vesicles to nanodiscs.

[0075] As the (E) anionic surfactant used in the cosmetic of the present invention, a sulfonate-type anionic surfactant is preferred. Examples of sulfonate-type anionic surfactants include sulfosuccinate diester salts, alkyl allyl sulfonates, alkyl ether sulfonates, sulfosuccinate salts, acylmethyl taurate, acyl taurate, potassium hexadecyl phosphate, and potassium cocoyl glutamate. Among these, acylmethyl taurate, potassium hexadecyl phosphate, and potassium cocoyl glutamate are preferred.

[0076] In this invention, N-acylmethyl taurate is particularly preferred as an (E) anionic surfactant. Furthermore, among the N-acylmethyl taurates shown in formula (4), N-stearoyl-N-methyl taurate is preferred.

[0077]

[0078] (E) The amount of the ingredient is preferably 0.01 to 1% by mass relative to the total amount of the cosmetic, more preferably 0.01 to 0.1% by mass, and even more preferably 0.01 to 0.06% by mass. When the amount is less than 0.01% by mass, the nanodiscs are sometimes not stable enough, and when it exceeds 1% by mass, the vesicles that are the precursors of the nanodiscs may sometimes dissolve or hinder the formation of the nanodiscs.

[0079] In addition, the ratio of (B) polyoxyalkylene modified silicone and (E) anionic surfactant by mass is preferably 1:0.01 to 1:0.06.

[0080] Generally, whitening agents can be incorporated into sunscreen cosmetics, but it is known that when a salt-type whitening agent is incorporated into an aqueous phase as the external phase, its stability tends to deteriorate. The cosmetic of the present invention emulsifies the oil by forming nanodiscs from a specific organosilicon surfactant and confines the incorporated oil, thereby enhancing the emulsifying power. Therefore, even when a salt-type whitening agent is incorporated into the aqueous phase, it exhibits excellent vibrational stability.

[0081] The whitening agent (hereinafter sometimes simply referred to as "(F) ingredient") incorporated in the cosmetics of the present invention is not particularly limited as long as it is a commonly used ingredient in cosmetics. Specific examples include L-ascorbic acid and its derivatives, tranexamic acid and its derivatives, alkoxysalicylic acid and its derivatives, glycyrrhizic acid and its derivatives, nicotinic acid and its derivatives, etc. In the cosmetics of the present invention, one or more of the aforementioned agents may be incorporated.

[0082] As derivatives of L-ascorbic acid, examples include L-ascorbic acid monoalkyl esters such as L-ascorbic acid monostearate, L-ascorbic acid monopalmitate, and L-ascorbic acid monooleate; L-ascorbic acid monoesters such as L-ascorbic acid monophosphate and L-ascorbic acid-2-sulfate; L-ascorbic acid dialkyl esters such as L-ascorbic acid distearate, L-ascorbic acid dipalmitate, and L-ascorbic acid dioleate; L-ascorbic acid trialkyl esters such as L-ascorbic acid tristearate, L-ascorbic acid tripalmitate, and L-ascorbic acid trioleate; L-ascorbic acid triesters such as L-ascorbic acid triphosphate; and L-ascorbic acid glucosides such as L-ascorbic acid 2-glucoside. In this invention, L-ascorbic acid, L-ascorbic acid phosphate, L-ascorbic acid-2-sulfate, L-ascorbic acid-2-glucoside, and their salts are preferably used.

[0083] Examples of tranexamic acid derivatives include dimers of tranexamic acid (e.g., trans-4-(trans-aminomethylcyclohexanecarbonyl)aminomethylcyclohexane carboxylic acid hydrochloride), esters of tranexamic acid and hydroquinone (e.g., 4-(trans-aminomethylcyclohexane carboxylic acid 4'-hydroxyphenyl ester), esters of tranexamic acid and gentianic acid (e.g., 2-(trans-4-aminomethylcyclohexylcarbonyloxy)-5-hydroxybenzoic acid), and amides of tranexamic acid (e.g., trans-4-aminomethylcyclohexane carboxylic acid formamide, trans-4-(p-methoxybenzoyl)aminomethylcyclohexane carboxylic acid, trans-4-guanidinylmethylcyclohexane carboxylic acid, etc.). In this invention, tranexamic acid and its salts are preferred.

[0084] The derivatives of alkoxysalicylic acid are formed by substituting an alkoxy group for any hydrogen atom at the 3, 4, or 5 position of salicylic acid. The alkoxy group is preferably any one of methoxy, ethoxy, propoxy, isopropoxy, butoxy, or isobutoxy, and more preferably methoxy or ethoxy. Specifically, examples of exemplified compounds 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, and 5-propoxysalicylic acid. In this invention, methoxysalicylic acid and its salts (potassium methoxysalicylate) are preferred.

[0085] Examples of glycyrrhizic acid derivatives include salts of glycyrrhizic acid and esters of glycyrrhizic acid with higher alcohols. In this invention, glycyrrhizic acid and its salts (dipotassium glycyrrhizate, monoammonium glycyrrhizate, etc.) are preferred.

[0086] There are no particular limitations on the salts used in the aforementioned reagents. For example, alkali metal salts or alkaline earth metal salts such as sodium salts, potassium salts, and calcium salts can be listed. In addition, ammonium salts and amino acid salts can also be listed.

[0087] Examples of nicotinic acid and its derivatives include nicotinic acid, benzyl nicotinate, nicotinamide, and dl-α-tocopherol nicotinic acid. In this invention, nicotinamide is preferred.

[0088] (F) The amount of whitening agent in the formulation relative to the total amount of cosmetics is 0.05 to 10% by mass, preferably 0.1 to 7% by mass, and even more preferably 0.5 to 5% by mass. When the amount in the formulation is less than 0.05% by mass, it is difficult to obtain sufficient efficacy, and when it exceeds 10% by mass, there is a tendency for the stability and usability to deteriorate.

[0089] The whitening agent of the present invention (F) can be dissolved or dispersed in an aqueous phase together with other aqueous components.

[0090] (G) Dispersant

[0091] In the cosmetics of the present invention, one or more (G) dispersants may be incorporated. Specific examples of dispersants include sorbitan sesquiisostearate, isostearic acid, palmitic acid, polyhydroxystearic acid, etc. Among these, sorbitan sesquiisostearate and isostearic acid are particularly preferred examples, and one or both of these may be incorporated.

[0092] (G) The dispersant is a selectively incorporated ingredient in the cosmetic of the present invention. Therefore, it is not necessarily required to be incorporated. However, when it is incorporated, it is preferable to incorporate it to the extent that the effect of the formulation is confirmed and the adverse effects such as impaired user experience due to excessive dosage are not confirmed. The preferred amount of (G) dispersant in the cosmetic of the present invention is approximately 0.01 to 1% by mass relative to the total amount of the cosmetic.

[0093] The water incorporated into the cosmetic of this invention can be selected from ion-exchanged water, purified water, tap water, natural water, etc., as needed. The amount incorporated is the remainder (mass %) of the sum of the essential ingredients of this invention and any other optional ingredients. Generally, it is suitable to be about 30-70% by mass relative to the total amount of the cosmetic.

[0094] In the water-in-oil emulsion cosmetic of the present invention, in addition to the above-mentioned components, other arbitrary additives commonly used in cosmetics, pharmaceuticals, and other topical skin preparations may be appropriately added as needed, without impairing the purpose or effect of the present invention. These additives may include, for example, oils, waxes, higher fatty acids, higher alcohols, oil-phase thickeners, surfactants, water-soluble ultraviolet absorbers, pigments, chelating agents, lower alcohols, polyols, pH adjusters, antioxidants, powder components, fragrances, etc. However, the invention is not limited to these examples.

[0095] The vesicles used as precursors to nanodisks in this invention can be prepared by thoroughly mixing (B) polyoxyalkylene-modified organosilicon with (A) aqueous component, and then adding the mixture dropwise to an aqueous phase containing all components except (A) while stirring. The mixing state of the aforementioned (B) polyoxyalkylene-modified organosilicon and (A) aqueous component only needs to confirm that the mixture is transparent and in a single-phase state; for example, this can be achieved by mixing at room temperature to 90°C for 1 to 30 minutes. Using this method, vesicle particles with an average particle size of 30 to 150 nm as measured by dynamic light scattering can be obtained.

[0096] The vesicles of the present invention can be manufactured by conventional methods to maintain the form of oily components within the vesicle's molecular membrane. Specifically, in the process of mixing (B) polyoxyalkylene-modified silicone and (A) aqueous components, oil-soluble components such as fragrances are added and mixed to manufacture vesicles in which the oil-soluble components are maintained within the vesicle's molecular membrane.

[0097] The water-in-oil emulsion cosmetic of the present invention is formed by adding anionic surfactants and oils to an aqueous phase containing vesicles, dispersing them under strong stirring force, thereby emulsifying them with nanodiscs transferred from the vesicles. The cosmetic of the present invention is stabilized by a three-phase structure of water phase-nanodisc phase-oil phase, in which nanodiscs (phase) are attached to the oil phase (oil droplets).

[0098] Therefore, the water-in-oil emulsion cosmetic of the present invention is characterized in that nanodiscs formed by polyoxyalkylene-modified organosilicon are attached (locally present) at the oil-water interface, i.e., around the oil droplets formed by the oil phase. The aforementioned nanodiscs have a major axis of 20 nm to 1000 nm.

[0099] The three-phase structure of the water-nanodisc phase-oil phase in the water-in-oil emulsion cosmetic of the present invention can be formed by conventional methods. Specifically, under stirring, polyoxyalkylene-modified organosilicon is added dropwise to the aqueous component to form vesicle particles, resulting in a vesicle aqueous dispersion. An oily component, separately mixed and dissolved with an anionic surfactant, is then added to this vesicle aqueous dispersion. During dispersion using strong stirring, the vesicles transfer to nanodiscs, forming a three-phase structure of water-nanodisc phase-oil phase. In the aqueous phase, the oil droplets formed by the oily component emulsify and disperse, resulting in the localized presence of nanodiscs on the surface of the oil droplet particles. Therefore, the emulsification stability is excellent, and the user experience (hydrating feel, non-sticky) is also excellent. It should be noted that the stirring device used is not particularly limited; for example, a homogenizer or disperser can be used.

[0100] It should be noted that, in this invention, the vesicle particles formed in the aqueous phase can be sufficiently shaped into tiny particles by applying high shear in the aforementioned homogenizer or similar apparatus, thereby uniformly dispersing them in the aqueous phase. The degree of high shear is not particularly limited; typically, it is set to approximately 5 minutes under conditions of 7000–12000 rpm using a homogenizer.

[0101] The cosmetic of the present invention is obtained by forming vesicle particles in an aqueous phase, adding an anionic surfactant to the vesicle dispersion, and then adding an oily component for emulsification.

[0102] Therefore, the method for manufacturing the water-in-oil emulsion cosmetic of the present invention comprises the following steps: a vesicle forming step of mixing (A) an aqueous component and (B) a polyoxyalkylene modified organosilicon to form vesicles; a step of adding an anionic surfactant to the vesicle dispersion obtained in the vesicle forming step to obtain a mixture; and an emulsification step of emulsifying the separately mixed and dissolved oily component in the mixture obtained by the aforementioned steps while applying stirring and shear force.

[0103] In the aforementioned vesicle formation process, (A) aqueous component and (B) polyoxyalkylene modified organosilicon are dissolved in advance, and the dissolved product is mixed with the remaining aqueous phase component to obtain a vesicle dispersion in the aqueous phase. Alternatively, (B) polyoxyalkylene modified organosilicon is mixed and stirred in an aqueous phase containing (A) aqueous component and aqueous components other than (A) component to obtain a vesicle dispersion in the aqueous phase.

[0104] The cosmetic of the present invention has the moisturizing feel characteristic of oil-in-water emulsions and provides excellent UV protection. Furthermore, although the nanodiscs of the present invention contain a large amount of oil that cannot be combined with conventional solubilizers, a refreshing feel is still achieved.

[0105] The cosmetic of this invention is suitable for use in various dosage forms such as cream, lotion, and liquid. As a product form, it can be a skin care cosmetic with sun protection effects, or a makeup cosmetic such as a makeup base or foundation with sun protection effects.

[0106] Example

[0107] The present invention is further described in detail below with reference to specific examples, but the invention is not limited thereto. Unless otherwise specified, the amount of a compound is expressed as the percentage of the mass of that component relative to the compounded system. Before each specific example is described, the evaluation method used is explained.

[0108] 1. Vibration stability

[0109] Place 30 ml of the prepared sample into a resin tube and vibrate at a frequency above 10 Hz for 30 minutes. Visually observe the emulsification separation and powder aggregation state of the sample after standing. Evaluation is based on the following criteria.

[0110] A: No emulsification disruption or powder aggregation was observed.

[0111] B: Emulsification disruption and powder aggregation are not very common.

[0112] C: Emulsification disruption and powder aggregation are visible.

[0113] D: Emulsification breakdown and powder aggregation are clearly visible.

[0114] 2. Water resistance

[0115] Water resistance is determined by measuring the UV-deficient capacity of UV-deficient agents (UV absorbers and UV scatterers) incorporated in cosmetics before and after a water bath, and calculating the proportion of UV-deficient capacity remaining after the water bath (residual absorbance). Specifically, the water resistance is measured using a test plate (S plate) (5×5cm V-groove PMMA plate, SPFMASTER-PA01) at a concentration of 2 mg / cm³. 2 The amount of each cosmetic sample was added dropwise and spread with a finger for 60 seconds. The absorbance of the coating film formed after drying for 15 minutes was measured using a Hitachi U-3500 self-recording spectrophotometer. Glycerin, which does not absorb ultraviolet light, was used as a control, and the absorbance (Abs) was calculated using the following formula.

[0116] Abs = -log(T / To)

[0117] T: Transmittance of the sample, To: Transmittance of glycerol

[0118] Immerse the plate being tested thoroughly in water with a hardness of 50–500. Under these conditions, stir in the water (using a 3-1 motor at 300 rpm) for 30 minutes. Then, allow it to dry for about 15–30 minutes until the water droplets on the surface disappear. Measure the absorbance again and calculate the Abs residual rate (the following formula) based on the cumulative Abs value before and after the water bath.

[0119] Abs Residual Rate (%) = (Cumulative Abs Value after Water Bath) / (Cumulative Abs Value before Water Bath) × 100

[0120] Based on the calculated Abs residual rate, the following criteria are used for judgment.

[0121] A: More than 80% remains.

[0122] B: Residue is more than 60% but less than 80%.

[0123] C: Residue is less than 60%.

[0124] (Examples 1-16, Comparative Examples 1-7)

[0125] Sunscreen cosmetics with the compositions shown in Tables 1 and 2 were prepared. Specifically, ethanol and vesicle-forming amphiphilic substances (polyoxyalkylene-modified silicone and polyoxyethylene hydrogenated castor oil) were mixed and stirred. Anionic surfactants and other aqueous components were then added to the mixture to obtain an aqueous solution. An oil-phase solution, obtained by separately mixing oily and powdered components, was then added to the aqueous solution while stirring, thereby obtaining an oil-in-water emulsion cosmetic. The prepared samples were evaluated for vibration stability and water resistance according to the aforementioned evaluation methods. The results are shown in the tables.

[0126] [Table 1]

[0127]

[0128] *1: KF-96L-1.5CS (manufactured by Shin-Etsu Chemical Co., Ltd.) has a volatilization rate of approximately 50%.

[0129] *2: KF-96L-6T (manufactured by Shin-Etsu Chemical Co., Ltd.) has a volatilization rate of less than 10%.

[0130] *3: KF-96A-20CS (manufactured by Shin-Etsu Chemical Co., Ltd.) has a volatilization rate of less than 10%.

[0131] Table 1 shows cosmetics prepared by altering the amphiphilic substance that forms vesicles, (E) anionic surfactants, and (C) oil components.

[0132] The cosmetics of Comparative Examples 1 and 2, which use polyoxyethylene hydrogenated castor oil as an amphiphilic substance for vesicle formation and do not contain (E) anionic surfactants, exhibit poor water resistance and sometimes fail to achieve sufficient vibration stability. Furthermore, even when using the (B) polyoxyalkylene-modified silicone of the present invention, the cosmetic of Comparative Example 3, which does not contain (E) anionic surfactants, exhibits poor vibration stability and water resistance.

[0133] The water-in-oil emulsion cosmetics of Examples 1 and 2 of the present invention exhibit excellent vibration stability and water resistance. In Comparative Example 4, which uses polyoxyethylene hydrogenated castor oil as an amphiphilic substance instead of the (B) polyoxyalkylene-modified organosilicon of the present invention, vibration stability is excellent, but water resistance is poor.

[0134] In the cosmetics of Examples 3 and 4, which used potassium hexadecyl phosphate and potassium cocoyl glutamate as the (E) anionic surfactants of the present invention, sufficient vibration stability and water resistance were obtained.

[0135] Furthermore, the cosmetics of Examples 1-7, which use polar oils (diisopropyl sebacate, cetyl ethylhexanoate, and UV absorbers) as oil components, and the cosmetics of Examples 8-10, which use silicone oil or hydrocarbon oil as oil components in addition to polar oils, all exhibit excellent vibration stability and water resistance. As shown in Example 7, it was confirmed that even without UV absorbers, excellent vibration stability and water resistance can be obtained simply by using polar oils.

[0136] [Table 2]

[0137]

[0138] *1: KF-96L-1.5CS (manufactured by Shin-Etsu Chemical Co., Ltd.) has a volatilization rate of approximately 50%.

[0139] *2: KF-96L-6T (manufactured by Shin-Etsu Chemical Co., Ltd.) has a volatilization rate of less than 10%.

[0140] *3: KF-96A-20CS (manufactured by Shin-Etsu Chemical Co., Ltd.) has a volatilization rate of less than 10%.

[0141] Table 2 shows cosmetics prepared by changing the proportion of low-molecular-weight oils relative to the total amount of oils other than UV absorbers.

[0142] In cosmetics containing isododecane (with a volatilization rate of over 90%) or polydimethylsiloxane (with a volatilization rate of approximately 50%), where the proportion of these low-molecular-weight oils relative to the total amount of oils other than UV absorbers exceeds 50%, vibration stability was significantly reduced.

[0143] On the other hand, cosmetics with a low molecular weight oil content of 50% relative to the total amount of oil (excluding UV absorbers) (Examples 12 and 15) and cosmetics with a low molecular weight oil content of 25% (Examples 13 and 16) both exhibited sufficient vibration stability.

[0144] (Formula example)

[0145] The following are examples of formulations for the water-in-oil emulsion cosmetic of the present invention. The present invention is not limited by these formulations and is necessarily defined by the claims. It should be noted that all amounts are expressed as a percentage of mass relative to the total amount of the product.

[0146] Formula Example 1. Sunscreen Beauty Serum

[0147] Ingredient Name and Amount (by Mass)

[0148] Water balance

[0149] Tranexamic acid 2

[0150] Potassium methoxysalicylate 1

[0151] EDTA-3Na 0.05

[0152] Glycerin 2

[0153] 1,3-Butanediol 8

[0154] Phenoxyethanol 0.5

[0155] Dimethacrylamide / sodium acryloyldimethyltaurate crosspolymer 1

[0157] Hydroxypropyl methylcellulose stearyl ether 0.1

[0158] Xanthan gum 0.1

[0159] Sodium methylstearoyl taurate 0.01

[0160] ethanol 8

[0161] PEG-12 polydimethylsiloxane 1.5

[0162] Polydimethylsiloxane 2

[0163] Diisopropyl sebacate 8

[0164] Organosilicon-treated titanium dioxide 2

[0165] Organosilicon treatment of yellow iron oxide 0.01

[0166] Organosilicon treatment of red iron oxide 0.01

[0167] 5-ethylhexyl methoxycinnamate

[0168] bis-ethylhexyloxyphenol methoxyphenyl triazine 2

[0169] Diethylaminohydroxybenzoyl benzoate 2

[0170] Sorbitan sesquiisostearate 0.5

[0171] Isostearic acid 0.5

[0172] Zinc oxide treated with silica and organosilicon 12

[0173] Formula Example 2. Sunscreen Beauty Serum

[0174] Ingredient Name and Amount (by Mass)

[0175] Water balance

[0176] Niacinamide 5

[0177] EDTA-3Na 0.05

[0178] Glycerin 2

[0179] 1,3-Butanediol 8

[0180] Phenoxyethanol 0.5

[0181] Dimethacrylamide / sodium acryloyldimethyltaurate crosspolymer 0.5

[0183] Hydroxypropyl methylcellulose stearyl ether 0.1

[0184] Xanthan gum 0.1

[0185] Sodium methylstearoyl taurate 0.01

[0186] ethanol 8

[0187] PEG-12 polydimethylsiloxane 1.5

[0188] Diisopropyl sebacate 8

[0189] Organosilicon-treated titanium dioxide 2

[0190] Organosilicon treatment of yellow iron oxide 0.01

[0191] Organosilicon treatment of red iron oxide 0.01

[0192] 5-ethylhexyl methoxycinnamate

[0193] tert-Butylmethoxydibenzoylmethane 2

[0194] Ethylhexyltriazine 1

[0195] Sorbitan sesquiisostearate 0.5

[0196] Isostearic acid 0.5

[0197] Zinc oxide treated with silica and organosilicon 12

[0198] Formula Example 3. Foundation

[0199] Ingredient Name and Amount (by Mass)

[0200] Water balance

[0201] EDTA-3Na 0.05

[0202] Glycerin 2

[0203] 1,3-Butanediol 8

[0204] Phenoxyethanol 0.5

[0205] Dimethacrylamide / sodium acryloyldimethyltaurate crosspolymer 0.5

[0207] Hydroxypropyl methylcellulose stearyl ether 0.1

[0208] Xanthan gum 0.1

[0209] Sodium methylstearoyl taurate 0.01

[0210] ethanol 8

[0211] PEG-12 polydimethylsiloxane 1.5

[0212] Diisopropyl sebacate 8

[0213] Organosilicon-treated titanium dioxide 5

[0214] Organosilicon treatment of yellow iron oxide 4

[0215] Organosilicon treatment of red iron oxide 2

[0216] Organosilicon-treated black iron oxide 0.1

[0217] 5-ethylhexyl methoxycinnamate

[0218] bis-ethylhexyloxyphenol methoxyphenyl triazine 2

[0219] Diethylaminohydroxybenzoyl benzoate 2

[0220] Sorbitan sesquiisostearate 0.5

[0221] Isostearic acid 0.5

[0222] Zinc oxide treated with silica and organosilicon 12

[0223] Formula Example 4. Foundation

[0224] Ingredient Name and Amount (by Mass)

[0225] Water balance

[0226] EDTA-3Na 0.05

[0227] Glycerin 2

[0228] 1,3-Butanediol 8

[0229] Phenoxyethanol 0.5

[0230] Dimethacrylamide / sodium acryloyldimethyltaurate crosspolymer 0.5

[0232] Hydroxypropyl methylcellulose stearyl ether 0.1

[0233] Xanthan gum 0.1

[0234] Sodium methylstearoyl taurate 0.01

[0235] ethanol 5

[0236] PEG-12 polydimethylsiloxane 1.5

[0237] Diisopropyl sebacate 8

[0238] Amino acid ester (isostearyl sebacate monoester, disodium stearoyl glutamate, aluminum hydroxide) treatment of titanium dioxide 5

[0239] Treatment of yellow iron oxide with amino acid esters (isostearyl sebacate monoester, disodium stearoyl glutamate, aluminum hydroxide) 1

[0240] Treatment of red iron oxide with amino acid esters (isostearyl sebacate monoester, disodium stearoyl glutamate, aluminum hydroxide) 4

[0241] Treatment of black iron oxide with amino acid esters (isostearyl sebacate monoester, disodium stearoyl glutamate, aluminum hydroxide) 0.1

[0242] Ethylhexyl salicylate 5

[0243] Octylene 5

[0244] Homosalt 5

[0245] Sorbitan sesquiisostearate 0.5

[0246] Isostearic acid 0.5

[0247] Zinc oxide treated with silica and organosilicon 12

[0248] Formula Example 5. Foundation

[0249] Ingredient Name and Amount (by Mass)

[0250] Water balance

[0251] EDTA-3Na 0.05

[0252] Glycerin 2

[0253] 1,3-Butanediol 8

[0254] Phenoxyethanol 0.5

[0255] Dimethacrylamide / sodium acryloyldimethyltaurate crosspolymer 0.5

[0257] Hydroxypropyl methylcellulose stearyl ether 0.1

[0258] Xanthan gum 0.1

[0259] Sodium methylstearoyl taurate 0.01

[0260] ethanol 5

[0261] PEG-12 polydimethylsiloxane 1.5

[0262] Diisopropyl sebacate 8

[0263] Amino acid ester (isostearyl sebacate monoester, disodium stearoyl glutamate, aluminum hydroxide) treatment of titanium dioxide 5

[0264] Treatment of yellow iron oxide with amino acid esters (isostearyl sebacate monoester, disodium stearoyl glutamate, aluminum hydroxide) 1

[0265] Treatment of red iron oxide with amino acid esters (isostearyl sebacate monoester, disodium stearoyl glutamate, aluminum hydroxide) 4

[0266] Treatment of black iron oxide with amino acid esters (isostearyl sebacate monoester, disodium stearoyl glutamate, aluminum hydroxide) 0.1

[0267] 5-ethylhexyl methoxycinnamate

[0268] bis-ethylhexyloxyphenol methoxyphenyl triazine 2

[0269] Diethylaminohydroxybenzoyl benzoate 2

[0270] Sorbitan sesquiisostearate 0.5

[0271] Isostearic acid 0.5

[0272] Zinc oxide treated with silica and organosilicon 12

[0273] Formula Example 6. Sunscreen

[0274] Ingredient Name and Amount (by Mass)

[0275] Water balance

[0276] Palmitic dextrin 1

[0277] PEG / PPG-9 / 2 dimethyl ether 2

[0278] EDTA-3Na 0.05

[0279] Glycerin 2

[0280] 1,3-Butanediol 8

[0281] Phenoxyethanol 0.5

[0282] Dimethacrylamide / sodium acryloyldimethyltaurate crosspolymer 0.5

[0284] Hydroxypropyl methylcellulose stearyl ether 0.1

[0285] Xanthan gum 0.1

[0286] Sodium methylstearoyl taurate 0.01

[0287] ethanol 8

[0288] PEG-12 polydimethylsiloxane 1.5

[0289] Diisopropyl sebacate 8

[0290] 5-ethylhexyl methoxycinnamate

[0291] bis-ethylhexyloxyphenol methoxyphenyl triazine 2

[0292] Ethylhexyltriazine 1

[0293] Sorbitan sesquiisostearate 0.5

[0294] Isostearic acid 0.5

[0295] Zinc oxide treated with silica and organosilicon 12

[0296] Formula Example 7. Sunscreen

[0297] Ingredient Name and Amount (by Mass)

[0298] Water balance

[0299] EDTA-3Na 0.05

[0300] Glycerin 2

[0301] 1,3-Butanediol 8

[0302] Phenoxyethanol 0.5

[0303] Dimethacrylamide / sodium acryloyldimethyltaurate crosspolymer 0.5

[0305] Hydroxypropyl methylcellulose stearyl ether 0.1

[0306] Xanthan gum 0.1

[0307] Sodium methylstearoyl taurate 0.01

[0308] ethanol 8

[0309] PEG-12 polydimethylsiloxane 1.5

[0310] Diisopropyl sebacate 8

[0311] 10g of triglycerides (ethylhexanoate)

[0312] Sorbitan sesquiisostearate 0.5

[0313] Isostearic acid 0.5

[0314] Zinc oxide treated with silica and organosilicon 12

[0315] Organosilicon-treated titanium dioxide 5

Claims

1. A water-in-oil type sunscreen cosmetic, comprising: (A) Aqueous components selected from monohydric alcohols and dihydric alcohols, (B) Polyoxyalkylene-modified organosilicon with HLB less than 10 (C) Oils containing diisopropyl sebacate, or oils containing a combination of cetyl ethylhexanoate and a UV absorber. (D) Ultraviolet scattering agents with hydrophobic surfaces, and (E) Anionic surfactants, The aqueous component (A) is a combination of monohydric alcohols and dihydric alcohols, and its total amount is 1-45% by mass relative to the total amount of the cosmetic. When low-molecular-weight oils are incorporated into the oil composition described in (C), the proportion of low-molecular-weight oils, by mass percentage, is 50% or less relative to the total amount of oils other than UV absorbers. The low-molecular-weight oil is an oil with a evaporation rate of more than 30% per hour at 25°C. The evaporation rate is defined as the rate of change of weight per hour, measured by gravimetric method at 25°C, after adding 0.2g of the sample to a glass dish with filter paper placed on it. The amount of ingredient (D) is 1-30% by mass relative to the total amount of the cosmetic. The (E) anionic surfactant is N-acylmethyl taurate, and the amount of (E) component relative to the total amount of cosmetic is 0.01 to 1 by mass.

2. The water-in-oil type sunscreen cosmetic according to claim 1, wherein, The low-molecular-weight oil is selected from one or more of the following groups: isododecane and polydimethylsiloxane with an average degree of polymerization of less than 650.

3. The water-in-oil type sunscreen cosmetic according to claim 1, wherein, The amount of ultraviolet absorber incorporated is 5 to 25% of the total mass of the cosmetic product.

4. The water-in-oil type sunscreen cosmetic according to claim 1, wherein, Nanodiscs formed from the (B) polyoxyalkylene-modified organosilicon adhere to the oil-water interface.

5. The water-in-oil type sunscreen cosmetic according to claim 1, wherein, The oil component (C) further comprises one or more selected from hydrocarbon oils and silicone oils.

6. The water-in-oil type sunscreen cosmetic according to claim 1, wherein, The component (B) is PEG-12 polydimethylsiloxane.

7. The water-in-oil type sunscreen cosmetic according to claim 1, further comprising (F) a whitening agent.

8. The water-in-oil type sunscreen cosmetic according to claim 1, further comprising (G) a dispersant.

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