Water-in-oil type emulsified external composition

Abstract

To provide a water-in-oil emulsion composition for external use that contains urea and has excellent emulsion stability.SOLUTION: A water-in-oil emulsion composition for external use contains urea in combination with fat-soluble vitamin and polyglycerol fatty acid ester. The water-in-oil emulsion composition can have excellent emulsion stability.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a water-in-oil emulsion composition for external use which contains urea and has excellent emulsion stability. [Background technology]

[0002] Urea has a water-retaining effect by forming hydrogen bonds with water in the keratin, and an effect of removing unnecessary keratin by protein denaturation, and is used in external compositions. On the other hand, emulsion preparations can be mixed with aqueous and oily components, can be applied to various formulations, and have an excellent feel when applied to the skin, so they are widely used in the field of external compositions. In particular, water-in-oil emulsion preparations are superior to oil-in-water emulsion preparations in skin protection, skin softening, elimination, etc., and are therefore applied to various external compositions.

[0003] Therefore, a water-in-oil type emulsion composition for topical use containing urea is expected to have both the functionality of urea and the properties of a water-in-oil type emulsion preparation, and is expected to be a topical composition with excellent functionality. However, when urea is added to a water-in-oil type emulsion composition for topical use, there is a problem that the emulsion stability is significantly reduced.

[0004] Therefore, conventionally, formulation techniques for improving emulsion stability in a water-in-oil type emulsion composition for external use containing urea have been studied. For example, Patent Document 1 discloses that a water-in-oil type emulsion composition containing 1-30% by weight of an emulsifier composition consisting of a specific polyhydric alcohol and a microcrystalline wax, 1-30% by weight of urea, 0.1-10% by weight of an ammonium salt of an organic acid or an inorganic acid, 5-50% by weight of an oil component, and the remainder of water, can have excellent emulsion stability.

[0005] However, in order to further improve the emulsion stability of water-in-oil emulsion compositions for topical use containing urea and to respond to diversification of formulations, there is a demand for further development of formulation techniques that improve the emulsion stability of the water-in-oil emulsion compositions for topical use. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Special Publication No. 62-31975 Summary of the Invention [Problem to be solved by the invention]

[0007] An object of the present invention is to provide a water-in-oil emulsion composition for external use which contains urea and has excellent emulsion stability. [Means for solving the problem]

[0008] The present inventors have conducted extensive research to solve the above problems and have found that a water-in-oil emulsion composition for topical use containing urea, a fat-soluble vitamin, and a polyglycerol fatty acid ester can have excellent emulsion stability. Furthermore, the inventors have also found that the water-in-oil emulsion composition for topical use has significantly improved skin permeability of the components contained therein. The present invention has been completed through further research based on these findings.

[0009] That is, the present invention provides the following aspects. Item 1. A water-in-oil type emulsion composition for external use comprising (A) urea, (B) a fat-soluble vitamin, and (C) a polyglycerol fatty acid ester. Item 2. The water-in-oil emulsion composition for external use according to Item 1, further comprising (D) a dextrin fatty acid ester. Item 3. The water-in-oil emulsion composition for external use according to Item 1 or 2, wherein the component (B) is vitamin A and / or vitamin E. Item 4. The water-in-oil emulsion composition for external use according to any one of Items 1 to 3, comprising 5 to 20% by weight of the component (A), 0.21 to 15% by weight of the component (B), and 0.5 to 10% by weight of the component (C). Item 5. The water-in-oil emulsion composition for external use according to any one of Items 2 to 4, containing 0.1 to 5% by weight of the component (D). Item 6. A method for emulsifying and stabilizing a water-in-oil type emulsion composition for topical use that contains urea, the method comprising incorporating (A) urea, (B) a fat-soluble vitamin, and (C) a polyglycerol fatty acid ester into the water-in-oil type emulsion composition for topical use. Effect of the Invention

[0010] The water-in-oil emulsion composition for topical use of the present invention has excellent emulsion stability despite containing urea. Furthermore, the water-in-oil emulsion composition for topical use of the present invention has remarkably excellent skin permeability of the components contained therein. [Brief description of the drawings]

[0011] [Figure 1] FIG. 2 is a diagram showing typical examples of each evaluation criterion when evaluating emulsion stability in Test Example 1. [Diagram 2] FIG. 2 is a diagram showing typical examples of each evaluation criterion when evaluating permeability in Test Example 1. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] 1.Water-in-oil emulsion topical composition The water-in-oil emulsion composition for topical use of the present invention is characterized by containing (A) urea, (B) fat-soluble vitamin, and (C) polyglycerol fatty acid ester. The water-in-oil emulsion composition for topical use of the present invention will be described in detail below. In this specification, "emulsion stability" refers to the property of being able to stably maintain the water-in-oil emulsion form and suppress phase separation due to storage.

[0013] [(A)Urea] The water-in-oil emulsion composition for topical use of the present invention contains urea (sometimes referred to as "component (A)"). Urea is a well-known component known to have the effect of retaining moisture in keratin and removing unnecessary keratin. In the prior art, water-in-oil emulsion compositions for topical use containing urea had the drawback of low emulsion stability, but the present invention overcomes this drawback by including a fat-soluble vitamin and a polyglycerol fatty acid ester, which will be described later, and thus makes it possible to provide excellent emulsion stability.

[0014] The content of component (A) in the water-in-oil emulsion topical composition of the present invention is appropriately set depending on the medicinal effect to be imparted, the use of the water-in-oil emulsion topical composition, etc., and may be 5 to 20% by weight, preferably 10 to 20% by weight. In the prior art, when the content of urea in the water-in-oil emulsion topical composition is 5% by weight or more (particularly 10% by weight or more), there is a strong tendency for emulsion stability to be impaired, but the water-in-oil emulsion topical composition of the present invention can have excellent emulsion stability even if it contains 5% by weight or more (particularly 10% by weight or more) of urea.

[0015] [(B) Fat-soluble vitamins] The water-in-oil emulsion composition for external use of the present invention contains a fat-soluble vitamin (sometimes referred to as "ingredient (B)").

[0016] Specific examples of fat-soluble vitamins used in the present invention include vitamins A, E, D, and K.

[0017] Vitamin A refers to vitamin A1 (retinol, retinal, retinoic acid), vitamin A2 (3-dehydroretinol, 3-dehydroretinal, 3-dehydroretinoic acid), and their derivatives. Specific examples of vitamin A1 derivatives include retinol organic acid esters such as retinol acetate, retinol butyrate, retinol propionate, retinol palmitate, retinol linoleate, retinol octylate, retinol laurate, retinol oleate, and retinol linoleate.

[0018] Vitamin E refers to tocopherol, tocotrienol, and their derivatives. Specific examples of tocopherol derivatives include tocopherol organic acid esters such as tocopherol acetate, tocopherol succinate, tocopherol linoleate, tocopherol linolenate, tocopherol nicotinate, and tocopherol (linoleate / oleate). Tocopherol, tocotrienol, and their derivatives may be any of α-, β-, γ-, and δ-, and may be either d- or dl-form.

[0019] Examples of vitamin D include vitamin D2, vitamin D3, and derivatives thereof. More specific examples of vitamin D include ergocalciferol, cholecalciferol, preergocalciferol, 5,6-trans-ergocalciferol, isoergocalciferol, isopyroergocalciferol, precholecalciferol, 5,6-trans-cholecalciferol, 25-hydroxycholecalciferol, 1α-hydroxycholecalciferol, and 7-dehydrocholesterol.

[0020] Vitamin K refers to vitamin K1 (phylloquinone), vitamin K2 (menaquinone), vitamin K3 (menadione), vitamin K4 (menadiol), vitamin K5 (4-amino-2-methyl-1-naphthol), and their derivatives.

[0021] Among these fat-soluble vitamins, from the viewpoint of providing even better emulsion stability, preferred are vitamins A and E, more preferred are retinol, tocopherol, and derivatives thereof, and even more preferred are retinol palmitate and tocopherol acetate.

[0022] These fat-soluble vitamins may be used alone or in combination of two or more.

[0023] From the viewpoint of providing even better emulsion stability, a suitable example of the fat-soluble vitamin used in the present invention is a combination of vitamin A and vitamin E. When vitamin A and vitamin E are used in combination, their ratio is not particularly limited, but for example, 5 to 1000 parts by weight, preferably 15 to 500 parts by weight, and more preferably 20 to 400 parts by weight of vitamin E per 100 parts by weight of vitamin A.

[0024] The content of the (B) component in the water-in-oil emulsion composition for external use of the present invention is, for example, 0.21 to 15% by weight, preferably 0.7 to 10% by weight, more preferably 1 to 8% by weight, based on the total amount of the (B) component. More specifically, when vitamin A is used as the (B) component, the content of vitamin A is 0.2 to 5% by weight, preferably 0.5 to 5% by weight, more preferably 0.5 to 3% by weight; when vitamin E is used as the (B) component, the content of vitamin E is 0.01 to 10% by weight, preferably 0.2 to 5% by weight, more preferably 0.5 to 5% by weight.

[0025] In the water-in-oil emulsion composition for external use of the present invention, the ratio of the (A) component to the (B) component may be within a range that satisfies the above-mentioned respective contents of both components, and for example, the total amount of the (B) component is 1.05 to 300 parts by weight, preferably 3.5 to 200 parts by weight, more preferably 10 to 80 parts by weight per 100 parts by weight of the (A) component. More specifically, when vitamin A is used as the (B) component, the vitamin A is 1 to 100 parts by weight, preferably 2 to 60 parts by weight, more preferably 2.5 to 30 parts by weight per 100 parts by weight of the (A) component; when vitamin E is used as the (B) component, the vitamin E is 0.05 to 200 parts by weight, preferably 0.1 to 100 parts by weight, more preferably 4 to 50 parts by weight per 100 parts by weight of the (A) component.

[0026] [(C) Polyglycerol fatty acid ester] The water-in-oil emulsion composition for topical use of the present invention contains a polyglycerol fatty acid ester (sometimes referred to as "component (C)").

[0027] The polyglycerol fatty acid ester is an ester of a fatty acid or a polymer thereof with polyglycerol.

[0028] In the polyglycerol fatty acid ester, the number of ester bonds (the number of fatty acids bonded per one polyglycerol molecule) is, for example, 1 to 10, preferably 1 to 5, and more preferably 1.

[0029] Examples of fatty acids constituting the polyglycerol fatty acid ester include fatty acids having 8 to 30 carbon atoms or polymers thereof, preferably fatty acids having 12 to 22 carbon atoms or polymers thereof, and more preferably fatty acids having 12 to 18 carbon atoms or polymers thereof. The fatty acids constituting the polyglycerol fatty acid ester may be either linear or branched, and may be either saturated or unsaturated fatty acids.

[0030] The degree of polymerization of the polyglycerin constituting the polyglycerin fatty acid ester (the number of glycerin bonds) is, for example, 2-10, and preferably 4-8.

[0031] Specific examples of polyglycerol fatty acid esters include polyglyceryl laurate, polyglyceryl stearate, polyglyceryl oleate, polyglyceryl myristate, polyglyceryl palmitate, polyglyceryl isostearate, polyglyceryl distearate, polyglyceryl diisostearate, polyglyceryl trioleate, polyglyceryl pentaoleate, polyglyceryl decaoleate, polyglyceryl tristearate, polyglyceryl triisostearate, polyglyceryl pentastearate, polyglyceryl ricinoleate, polyglyceryl polylaurate, polyglyceryl polystearate, polyglyceryl polyoleate, and polyglyceryl polyricinoleate.

[0032] Among the polyglycerol fatty acid esters, from the viewpoint of providing even better emulsion stability, preferred are polyglyceryl oleate, polyglyceryl polyricinoleate, and polyglyceryl laurate; more preferred are polyglyceryl-2 oleate, polyglyceryl-6 polyricinoleate (hexaglyceryl polyricinoleate), and polyglyceryl-10 laurate.

[0033] These polyglycerol fatty acid esters may be used alone or in combination of two or more.

[0034] The content of component (C) in the water-in-oil emulsion topical composition of the present invention is, for example, 0.5 to 10% by weight, preferably 1 to 9% by weight, more preferably 2 to 8% by weight, even more preferably 3 to 8% by weight, and particularly preferably 4 to 8% by weight.

[0035] In the water-in-oil emulsion composition for topical use of the present invention, the ratio of component (A) to component (C) may be within a range that satisfies the above-mentioned respective contents of both components. For example, the ratio of component (C) may be 2.5 to 200 parts by weight, preferably 5 to 160 parts by weight, more preferably 10 to 80 parts by weight, and even more preferably 10 to 30 parts by weight per 100 parts by weight of component (A).

[0036] [(D) Dextrin fatty acid ester] The water-in-oil emulsion composition for topical use of the present invention may further contain a dextrin fatty acid ester (sometimes referred to as "component (D)") in addition to the above-mentioned components. When the dextrin fatty acid ester is contained, it is possible to further improve the emulsion stability and the skin permeability of the contained components.

[0037] The dextrin fatty acid ester refers to an ester of a fatty acid and dextrin. The average degree of polymerization of the dextrin constituting the dextrin fatty acid ester is, for example, 3 to 150, preferably 10 to 50, and more preferably 20 to 40. The number of carbon atoms of the fatty acid constituting the dextrin fatty acid ester is, for example, 8 to 22, preferably 12 to 20, and more preferably 12 to 18. The fatty acid constituting the dextrin fatty acid ester may be either linear or branched, and may be either saturated fatty acid or unsaturated fatty acid.

[0038] Specific examples of dextrin fatty acid esters include dextrin laurate, dextrin myriphosphate, dextrin palmitate, dextrin stearate, dextrin oleate, dextrin isopalmitate, dextrin isostearate, dextrin behenate, and coconut oil fatty acid dextrin.

[0039] Among these dextrin fatty acid esters, dextrin palmitate is preferred from the viewpoint of providing even more excellent emulsion stability.

[0040] These dextrin fatty acid esters may be used alone or in combination of two or more.

[0041] When component (D) is contained in the water-in-oil emulsion topical composition of the present invention, the content thereof is, for example, 0.1 to 10% by weight, preferably 0.2 to 10% by weight, more preferably 0.2 to 5% by weight, and even more preferably 0.2 to 1% by weight.

[0042] In the water-in-oil emulsion composition for topical use of the present invention, the ratio of component (A) to component (D) may be within a range that satisfies the above-mentioned respective contents of both components. For example, the ratio of component (D) per 100 parts by weight of component (A) may be 0.5 to 200 parts by weight, preferably 0.5 to 100 parts by weight, more preferably 1 to 50 parts by weight, and even more preferably 1 to 10 parts by weight.

[0043] [(E) Polyhydric alcohol] The water-in-oil emulsion composition for topical use of the present invention may contain a polyhydric alcohol (sometimes referred to as "component (E)") as necessary in order to improve moisturizing properties, etc.

[0044] The type of polyhydric alcohol is not particularly limited as long as it is pharma- ceutically or cosmetically acceptable, and examples thereof include ethylene glycol, 1,3-butylene glycol, propylene glycol, isoprene glycol, diethylene glycol, dipropylene glycol, polypropylene glycol, polyethylene glycol, glycerin, diglycerin, etc. Among these polyhydric alcohols, glycerin is preferred.

[0045] These polyhydric alcohols may be used alone or in combination of two or more.

[0046] When the water-in-oil emulsion composition for external use of the present invention contains component (E), the content thereof is, for example, 1 to 30% by weight, preferably 5 to 25% by weight, and more preferably 7 to 20% by weight.

[0047] [(F) Glycyrrhizic acid and / or its salts] The water-in-oil emulsion composition for topical use of the present invention may contain glycyrrhizinic acid and / or a salt thereof (sometimes referred to as "component (F)") as necessary in order to impart anti-inflammatory or anti-allergic effects, etc.

[0048] The salt of glycyrrhizinic acid is not particularly limited as long as it is pharma- ceutically or cosmetically acceptable, and examples thereof include alkali metal salts such as sodium salts and potassium salts; ammonium salts, etc. These salts may be used alone or in combination of two or more.

[0049] Among glycyrrhizinic acid and its salts, preferred are salts of glycyrrhizinic acid, and more preferred are monoammonium glycyrrhizinate.

[0050] When the water-in-oil emulsion composition for external use of the present invention contains component (F), the content thereof is, for example, 0.1 to 10% by weight, preferably 0.2 to 5% by weight, and more preferably 0.5 to 3% by weight.

[0051] [(G) Oil phase base] The water-in-oil emulsion composition for external use of the present invention contains an oil phase base material (sometimes referred to as "component (G)") for forming an oil phase. Examples of the oil phase base material include higher alcohols, ester oils, hydrocarbon oils, higher fatty acids, vegetable oils, animal oils, silicone oils, etc. Among these, preferred are higher alcohols, ester oils, and hydrocarbon oils.

[0052] Examples of higher alcohols include monohydric alcohols having 10 to 24 carbon atoms, preferably monohydric alcohols having 12 to 22 carbon atoms, and more preferably monohydric alcohols having 14 to 22 carbon atoms. Specific examples of higher alcohols include capric alcohol, lauryl alcohol, myristyl alcohol, cetanol, stearyl alcohol, oleyl alcohol, linoleyl alcohol, arachidyl alcohol, behenyl alcohol, linoglyceryl alcohol, isostearyl alcohol, and 2-octyldodecanol.

[0053] Examples of ester oils include monoesters in which one fatty acid molecule is ester-bonded to one molecule of a monohydric or polyhydric alcohol, diesters in which two fatty acid molecules are ester-bonded to one molecule of a polyhydric alcohol, triesters in which three fatty acid molecules are ester-bonded to one molecule of a trihydric or higher polyhydric alcohol, and fatty acid cholesteryl in which a fatty acid is ester-bonded to cholesterol, etc. Specific examples of ester oils include octyldodecyl myristate, isopropyl myristate, and glyceryl triisooctanoate.

[0054] Examples of hydrocarbon oils include liquid paraffin, petrolatum, gelled hydrocarbons (such as Plastibase), polybutene, hydrogenated polyisobutene, squalane, and squalene.

[0055] These oil phase base materials may be used alone or in combination of two or more.

[0056] The content of component (G) in the water-in-oil emulsion composition for external use of the present invention is, for example, 5 to 68% by weight, preferably 7 to 55% by weight, and more preferably 7 to 40% by weight.

[0057] [(H) Aqueous phase base] The water-in-oil emulsion composition for topical use of the present invention contains water (sometimes referred to as "component (H)") as an aqueous phase base material for forming an aqueous phase. The content of component (H) in the water-in-oil emulsion composition for topical use of the present invention is, for example, 20 to 88% by weight, preferably 25 to 76% by weight, and more preferably 30 to 70% by weight.

[0058] [Other ingredients] In addition to the above-mentioned components, the water-in-oil emulsion composition for external use of the present invention may contain other additives that are commonly used in external use compositions, if necessary. Examples of such additives include nonionic surfactants (other than the polyglycerol fatty acid esters) with an HLB value of about 6 to 17, amphoteric surfactants, cationic surfactants, anionic surfactants, thickeners, monohydric lower alcohols, pH regulators, buffers, solubilizers, preservatives, antioxidants, stabilizers, fragrances, colorants, etc. When these additives are contained in the water-in-oil emulsion composition for external use of the present invention, the content of the additives may be appropriately set according to the type of additive used, etc.

[0059] In addition, the water-in-oil emulsion composition for external use of the present invention may contain pharmacological ingredients, if necessary, in addition to the above-mentioned ingredients. Examples of such pharmacological ingredients include steroids, antihistamines, local anesthetics, anti-inflammatory agents (other than glycyrrhetinic acid and / or its salts), moisturizers (other than urea), bactericides, antibacterial agents, antipruritic agents, skin protectants, blood circulation promoters, vitamins, mucopolysaccharides, etc. These pharmacological ingredients may be used alone or in combination of two or more. In addition, when these pharmacological ingredients are contained in the composition for external use of the present invention, the concentration of the pharmacological ingredients may be appropriately set according to the type of pharmacological ingredient used, the expected effect, etc.

[0060] [Formulation and Use] Since the water-in-oil emulsion composition for external use of the present invention is in the form of a water-in-oil emulsion, the preparation form is preferably a cream or ointment, and more preferably a cream.

[0061] The water-in-oil emulsion composition for topical use of the present invention has an excellent moisturizing effect due to urea, and can therefore be used for skin care purposes such as moisturizing the skin, improving wrinkles, etc. In addition, the water-in-oil emulsion composition for topical use of the present invention has an effect of removing unnecessary keratin due to urea, and can therefore also be used for the treatment of keratosis.

[0062] [Manufacturing method] The water-in-oil emulsion composition for external use of the present invention can be produced according to a known method for producing a water-in-oil emulsion preparation. Examples of the method for producing the emulsion composition for external use of the present invention include the following method. First, in addition to the components (A) and (H), the components (E), (F), and other water-soluble components are mixed as necessary to prepare a composition for aqueous phase. Separately, in addition to the components (B), (C), and (G), the components (D) and other lipophilic components are mixed as necessary to prepare a composition for oil phase. Next, the composition for aqueous phase is mixed dropwise with the composition for aqueous phase to emulsify, thereby obtaining the water-in-oil emulsion composition for external use of the present invention.

[0063] 2. Emulsion stabilization method The emulsion stabilization method of the present invention is a method for emulsion stabilization of a water-in-oil type emulsion composition for topical use containing urea, and is characterized in that the water-in-oil type emulsion composition for topical use contains (A) urea, (B) a fat-soluble vitamin, and (C) a polyglycerol fatty acid ester.

[0064] In the emulsion stabilization method of the present invention, the types and contents of the (A) to (C) used, the types and contents of other ingredients to be blended, the formulation form and use of the water-in-oil emulsion composition for topical use, etc. are the same as those in the above "1. Water-in-oil emulsion composition for topical use". EXAMPLES

[0065] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these.

[0066] The dextrin palmitate used in the test examples and formulation examples shown below is a product name "Leopearl KL2" (manufactured by Chiba Flour Milling Co., Ltd.; the degree of polymerization of dextrin is 20 to 30).

[0067] Test Example 1 1. Preparation of emulsion composition for external use <Examples 1 to 11 and Comparative Examples 1 to 9> The water-in-oil emulsion topical composition (cream) having the composition shown in Tables 1 and 2 was prepared by the following procedure. First, the oil phase composition was prepared by mixing the oil phase components and surfactants shown in Tables 1 and 2 in a predetermined amount and dissolving them by heating at 80°C. Separately, the aqueous phase components shown in Tables 1 and 2 were mixed to prepare the aqueous phase composition. Next, the aqueous phase composition heated to 80°C was gradually added to the oil phase composition heated to 80°C. While maintaining the temperature, the mixture was emulsified at 3000 rpm for 2 minutes using a homomixer (Aji Homomixer manufactured by Primix Corporation), and further cooled to room temperature while mixing using a paddle mixer to obtain a water-in-oil emulsion topical composition. The obtained water-in-oil emulsion topical composition was in a homogeneous emulsion state without phase separation immediately after preparation. <Comparative Example 9> A topical composition (cream) having the composition shown in Table 1 was prepared by the following procedure. First, a predetermined amount of each oil phase component shown in Table 1 was mixed and heated and dissolved at 80°C to prepare an oil phase composition. Separately, each aqueous phase component shown in Table 1 was mixed to prepare an aqueous phase composition. Next, the aqueous phase composition heated to 80°C was gradually added to the oil phase composition heated to 80°C and mixed to perform an emulsification operation, thereby obtaining a topical composition. The obtained topical composition was in a state of a mixture in which the oil phase and the aqueous phase were not emulsified immediately after preparation.

[0068] <Reference Examples 1 and 2> An oil-in-water emulsion topical composition (cream) having the composition shown in Table 1 was prepared by the following procedure. First, a predetermined amount of each oil phase component and surfactant shown in Table 1 was mixed and heated to 80°C to dissolve, to prepare an oil phase composition. Separately, a predetermined amount of each aqueous phase component shown in Table 1 was mixed to prepare an aqueous phase composition. Next, the oil phase composition heated to 80°C was gradually added to the aqueous phase composition heated to 80°C, and emulsified while mixing to obtain an oil-in-water emulsion topical composition (cream). The obtained oil-in-water emulsion topical composition was in a homogeneous emulsion state without phase separation immediately after preparation.

[0069] 2. Method for evaluating emulsion stability Immediately after preparation, 10 g of each external composition was filled and sealed in a 20 ml transparent glass container (screw tube No. 5, manufactured by Maruemu Co., Ltd., inner diameter 27 mm), and the low-temperature cycle stability test and high-temperature stability were evaluated. In the evaluation of low-temperature cycle stability, the temperature was raised from -20°C to 5°C, and then the temperature was lowered from 5°C to -20°C over 24 hours, which was defined as one cycle, and the test was carried out for a total of 10 days (10 cycles). In the evaluation of high-temperature stability, the composition was stored at 50°C for 30 days.

[0070] After the low-temperature cycle stability test and the high-temperature stability test, the appearance of each topical composition was observed, and the stability was evaluated according to the following evaluation criteria. For reference, typical appearances corresponding to the following evaluation criteria of ◎ to XX are shown in Figure 1. Stability evaluation criteria A: No phase separation occurred. ◯: A slight phase separation of a transparent liquid was observed on part of the upper surface of the composition for external use, but this did not pose any practical problem. Δ: Phase-separated transparent liquid is observed over the entire upper surface of the topical composition. ×: Part of the composition for external use is phase-separated. XX: The topical composition was completely phase-separated.

[0071] 3. Evaluation method for permeability The permeability of retinol palmitate or tocopherol acetate into the epidermis was evaluated for the topical compositions of Examples 1 to 11, Comparative Examples 3 and 9, and Reference Examples 1 and 2. First, the skin of the back of a hairless mouse was obtained, and 400 mg of each oil-in-water emulsion topical composition was applied to the entire surface using a spatula with a diameter of 3 cm. After storing for 30 minutes, the oil-in-water emulsion topical composition remaining on the skin surface was wiped off and frozen. In the frozen state, skin slices were prepared as samples for permeation evaluation. Next, a confocal Raman microscope (RAMANtouch, Nanophoton Corporation) was used to irradiate at 532 nm (output 500 mW) for 180 seconds to obtain a cross-sectional image of the epidermis in the depth direction, and the 1594 cm wavelength derived from retinol palmitate was measured. -1 or the Raman signal from tocopherol acetate at a wavelength of 1332 cm -1 In Example 4, the localized region of the Raman signal of 1332 cm 2 originating from tocopherol acetate was confirmed. -1 In Example 5, the Raman signal of retinol palmitate was evaluated at a wavelength of 1594 cm -1 Only the localized areas of the Raman signal were evaluated. For reference, typical images that correspond to the evaluation criteria below, ranging from ◎ to XX, are shown in Figure 2. In Figure 2, the area where the Raman signal was observed is colored green within the bar shown in the center. In Figure 2, the Raman signal (green) was observed in the area enclosed by the frame. Penetration evaluation criteria ◎: 1594 cm deep in the epidermis (up to a depth of about 40 μm from the surface of the epidermis) -1 and 1332 cm -1 A strong Raman signal is observed. ○: 1594 cm only in the shallow region of the epidermis (region up to a depth of about 30 μm from the epidermis surface) -1 and 1332 cm -1 A Raman signal of 100 nm is observed. △: 1594 cm only on the surface side of the epidermis (region up to a depth of about 20 μm from the epidermis surface) -1 and 1332 cm -1 A Raman signal of ×: 1594 cm only on the surface side of the epidermis (region up to a depth of about 10 μm from the epidermis surface) -1 and 1332 cm -1 A Raman signal of 100 nm is observed. ××: 1594 cm in the epidermis -1 and 1332 cm -1 No Raman signal is observed. 4.Results The results are shown in Tables 1 and 2. The oil-in-water emulsion topical composition had excellent emulsion stability regardless of the presence or absence of urea, but the penetration was insufficient (Reference Examples 1 and 2). In addition, the water-in-oil emulsion topical composition not containing urea had excellent emulsion stability when a surfactant other than polyglyceryl-6 polyricinoleate was used (Comparative Example 1), but the emulsion stability was reduced when polyglyceryl-6 polyricinoleate was used as the surfactant (Comparative Examples 4, 5, 7, and 8). In addition, the water-in-oil emulsion topical composition containing urea had insufficient emulsion stability when it did not contain both fat-soluble vitamins and polyglyceryl-6 polyricinoleate, or when it contained only one of them (Comparative Examples 2, 3, and 6). In contrast, the water-in-oil emulsion composition for external use containing urea, fat-soluble vitamins, and polyglyceryl-6 polyricinoleate had excellent emulsion stability and was also significantly superior in permeability to the epidermis (Examples 1 to 12). In particular, the water-in-oil emulsion composition for external use containing urea, fat-soluble vitamins, polyglyceryl-6 polyricinoleate, and dextrin palmitate showed significantly superior emulsion stability and permeability (Examples 10 and 11).

[0072] [Table 1]

[0073] [Table 2]

[0074] Prescription Examples An oil-in-water emulsion composition for external use (cream) was prepared having the composition shown in Table 3. The preparation procedure was the same as in the above-mentioned Examples 1 to 12. The obtained oil-in-water emulsion composition for external use was evaluated for emulsion stability and permeability in the same manner as in the above-mentioned Test Example 1, and excellent emulsion stability and permeability were found in all cases.

[0075] [Table 3]

Claims

1. A water-in-oil type emulsion composition for external use containing (A) urea, (B) vitamins A and / or E, and (C) a polyglycerol fatty acid ester (excluding those containing placenta, phosphatidylcholine, ceramide, proteoglycan, and taurine).

2. The water-in-oil emulsion composition for topical use according to claim 1 , further comprising (D) a dextrin fatty acid ester.

3. 3. The water-in-oil emulsion topical composition according to claim 1, comprising 5 to 20% by weight of the (A) component, 0.21 to 15% by weight of the (B) component, and 0.5 to 10% by weight of the (C) component.

4. 4. The water-in-oil emulsion composition for external use according to claim 2 or 3, comprising 0.1 to 5% by weight of component (D).

5. A method for emulsifying and stabilizing a water-in-oil type emulsion composition for topical use containing urea (excluding those containing placenta, phosphatidylcholine, ceramide, proteoglycan, and taurine), comprising incorporating (A) urea, (B) vitamins A and / or E, and (C) a polyglycerol fatty acid ester into the water-in-oil type emulsion composition for topical use.

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