W / o / w-type emulsion and method for producing same

Abstract

The purpose of the present invention is to provide: a W / O / W-type emulsion that exhibits good temporal stability even though the oil phase thereof contains silicone oil; and a method for producing the same. The present invention relates to a W / O / W-type emulsion comprising an inner aqueous phase, an oil phase containing silicone oil, and an outer aqueous phase, wherein the oil phase and / or the outer aqueous phase contains a water-insoluble powder.

Description

W / O / W type emulsion and method for producing the same

[0001] The present invention relates to a W / O / W type emulsion and a method for producing the same. More specifically, the present invention relates to a W / O / W type emulsion containing silicone oil and water-insoluble powder and having good stability over time, and a method for producing the same.

[0002] A W / O / W type (water-in-oil-in-water type) emulsion is a multi-phase emulsion in which an oil-in-water type (W / O type) emulsion is further emulsified and dispersed in an aqueous phase (outer aqueous phase). The W / O / W type emulsion is known as a formulation technique that can enhance the percutaneous absorption of active ingredients as compared with other emulsion types (Non-Patent Document 1), and is expected to be applied to various uses such as cosmetics, foods, and pharmaceuticals.

[0003] Silicone oil is a component widely used in the cosmetic field due to its high safety and various functionalities. For example, Patent Document 1 describes a highly water-containing and W / O / W type topical skin emulsifying composition in which whitening during application caused by an acrylic acid / alkyl methacrylate copolymer is suppressed by containing an organic amine and silicone oil.

[0004] Japanese Patent Application Laid-Open No. 2003-306411

[0005] Fragrance Journal, 1989, No. 4, p. 88-93

[0006] However, a W / O / W type emulsion containing silicone oil has a problem that its stability over time is insufficient and separation (phase separation) and phase inversion are likely to occur. Once a W / O / W type emulsion is separated or phase-inverted, it cannot return to the original emulsion.

[0007] An object of the present invention is to provide a W / O / W type emulsion having good stability over time and a method for producing the same, although the oil phase contains silicone oil.

[0008] As a result of intensive studies, the present inventor has found that a W / O / W type emulsion having good stability over time can be obtained by containing a water-insoluble powder in the oil phase and / or the outer aqueous phase in a W / O / W type emulsion in which the oil phase contains silicone oil, and has arrived at the present invention.

[0009] In other words, the present invention is not limited to the following, but relates to W / O / W type emulsions and methods for producing the same: [1] A W / O / W type emulsion comprising an internal aqueous phase, an oil phase, and an external aqueous phase, wherein the oil phase contains silicone oil, and the oil phase and / or the external aqueous phase contains water-insoluble powder. [2] The W / O / W type emulsion according to [1] above, wherein the external aqueous phase contains water-insoluble powder. [3] The W / O / W type emulsion according to [1] or [2] above, wherein the silicone oil is contained in an amount of 1 to 8% by weight relative to the total weight of the W / O / W type emulsion. [4] The W / O / W type emulsion according to any one of [1] to [3] above, wherein the external aqueous phase contains water-insoluble powder in an amount of 0.5 to 3% by weight relative to the total weight of the W / O / W type emulsion. [5] A W / O / W type emulsion according to any one of [1] to [4] above, wherein the oil phase contains 0.5 to 1% by weight of water-insoluble powder relative to the total weight of the W / O / W type emulsion. [6] A W / O / W type emulsion according to any one of [1] to [5] above, wherein the weight ratio of water-insoluble powder to silicone oil (water-insoluble powder / silicone oil) is 0.0625 to 3. [7] A W / O / W type emulsion according to any one of [1] to [6] above, wherein the silicone oil is at least one selected from the group consisting of dimethicone, diphenyl dimethicone, phenyl trimethicone, and cyclopentasiloxane. [8] A W / O / W type emulsion according to any one of [1] to [7] above, wherein the water-insoluble powder is insoluble in silicone oil. [9] A W / O / W emulsion according to any one of [1] to [8] above, wherein the water-insoluble powder is at least one selected from the group consisting of aluminum starch octenyl succinate, talc, silica, and cellulose.

[10] A W / O / W emulsion according to any one of [1] to [9] above, containing a silicone-based surfactant.

[11] A W / O / W emulsion according to

[10] above, wherein the silicone-based surfactant is cetyl PEG / PPG-10 / 1 dimethicone or lauryl PEG-9 polydimethylsiloxyethyl dimethicone.

[12] A W / O / W emulsion according to any one of [1] to

[11] above, wherein the oil phase further contains a solid oily component.

[13] A W / O / W emulsion according to

[12] above, wherein the solid oily component is wax.

[14] A W / O / W type emulsion according to any one of [1] to

[13] above, which is a topical skin preparation.

[15] A W / O / W type emulsion according to any one of [1] to

[14] above, which is a cream or lotion.

[16] A method for producing a W / O type emulsion, comprising the steps of: including a water-insoluble powder in the oil phase and / or outer aqueous phase; preparing a W / O type emulsion by mixing and emulsifying the inner aqueous phase and the oil phase containing silicone oil; and mixing and emulsifying the prepared W / O type emulsion with the outer aqueous phase.

[0010] According to the present invention, it is possible to provide a W / O / W type emulsion with good temporal stability despite the oil phase containing silicone oil, and a method for producing the same. The W / O / W type emulsion of the present invention is useful, for example, as a topical skin agent such as cosmetics.

[0011] Embodiments of the present invention are illustrated below. (W / O / W type emulsion) The W / O / W type emulsion of the present invention comprises an internal aqueous phase, an oil phase, and an external aqueous phase, wherein the oil phase contains silicone oil, and the oil phase and / or external aqueous phase contain water-insoluble powder. The W / O / W type emulsion of the present invention is typically a W / O / W type emulsion comprising an internal aqueous phase, an oil phase in which the internal aqueous phase is dispersed (emulsified), and an external aqueous phase in which the oil phase is dispersed (emulsified). The W / O / W type emulsion of the present invention may consist of the above-mentioned internal aqueous phase, oil phase, and external aqueous phase. In the W / O / W type emulsion, a W / O type emulsion in which the internal aqueous phase (internal aqueous phase droplets) is dispersed (emulsified) in the oil phase is dispersed (emulsified) in the external aqueous phase. The W / O / W type emulsion of the present invention has good temporal stability, meaning that separation and phase inversion over time do not occur easily, making it useful in fields such as cosmetics.

[0012] In this invention, "internal aqueous phase," "oil phase," and "external aqueous phase" may refer to either the phases of a W / O / W type emulsion or the respective solutions containing the components of each phase used in the production of the W / O / W type emulsion.

[0013] (Internal aqueous phase component) In the W / O / W type emulsion of the present invention, the internal aqueous phase contains water.

[0014] The W / O / W type emulsion of the present invention preferably further contains a metal salt in the internal aqueous phase. Including a metal salt as a component of the internal aqueous phase further improves the time-dependent stability of the W / O / W type emulsion. The metal salt is not particularly limited, but is preferably an amino acid metal salt such as magnesium sulfate, sodium citrate, or sodium glutamate, sodium lactate, or sodium chloride, and more preferably magnesium sulfate. One or more metal salts can be used. When the W / O / W type emulsion contains a metal salt, the content is not particularly limited, but may be, for example, 0.001 to 10% by weight, preferably 0.01 to 5% by weight, and more preferably 0.1 to 2% by weight in the W / O / W type emulsion.

[0015] The internal aqueous phase may contain water-soluble active ingredients as long as it does not impair the effects of the present invention. The water-soluble active ingredients may be one type or two or more types. Examples of water-soluble active ingredients include ascorbic acid derivatives (vitamin C derivatives) known as whitening ingredients, arbutin, chamomile ET, placenta extract, rucinol, hydroquinone, etc. Other examples include polyglycerin (e.g., polyglycerin-3, polyglycerin-4, etc.), diglycerin and betaine (trimethylglycine), as well as plant extracts and other beauty ingredients exemplified below.

[0016] When a W / O / W type emulsion contains a water-soluble active ingredient, its content is not particularly limited, but may be, for example, 0.0001 to 10% by weight, preferably 0.001 to 5% by weight, more preferably 0.005 to 5% by weight, and even more preferably 0.005 to 2% by weight in the W / O / W type emulsion. In one embodiment, it is also preferable that the content of the water-soluble active ingredient in the W / O / W type emulsion be 0.001 to 2% by weight.

[0017] (Oil Phase Components) The oil phase contains silicone oil. The silicone oil is a liquid oily component that is liquid at 25°C. In this specification, silicone oil refers to organosilicon compounds (polysiloxanes) having -Si-O- bonds (siloxane bonds) that do not have hydrophilic substituents such as polyether groups or polyglyceryl groups. Examples of silicone oils include: chain-like silicone oils such as dimethicone (dimethylpolysiloxane) and trisiloxane; methylphenyl silicone oils such as diphenyl dimethicone, phenyl trimethicone, and diphenylsiloxy phenyl trimethicone; cyclic silicone oils such as cyclopentasiloxane, cyclohexasiloxane, cyclomethicone, octamethylcyclotetrasiloxane, octamethylcyclopentasiloxane, and dodecamethylcyclohexasiloxane; and methylhydrogen silicones such as hydrogen dimethicone and methicone. Examples include: silicone oils; branched silicone oils such as methyl trimethicone; alkyl-modified silicone oils such as stearyl dimethicone, cetyl dimethicone, and caprylyl dimethicone; alcohol-modified silicone oils such as (stearoxymethicone / dimethicone) copolymer; amino-modified silicone oils such as amodimethicone, aminopropyl dimethicone, bis-aminopropyl dimethicone, and bis-cetearyl amodimethicone; highly polymerized methylpolysiloxane; higher alkoxy-modified silicones such as stearoxysilicone; and higher fatty acid ester-modified silicones. The silicone oil may be one type or two or more types. Note that the compounds exemplified as silicone surfactants described later are not included in the silicone oils of this invention.

[0018] In one embodiment, the silicone oil is preferably at least one selected from the group consisting of linear silicone oil, methylphenyl silicone oil, and cyclic silicone oil, and is more preferably linear silicone oil. Furthermore, the linear silicone oil is preferably dimethicone. The methylphenyl silicone oil is preferably diphenyl dimethicone or phenyl trimethicone. The cyclic silicone oil is preferably cyclopentasiloxane. In another embodiment, the silicone oil is preferably at least one selected from the group consisting of dimethicone, diphenyl dimethicone, phenyl trimethicone, and cyclopentasiloxane, and is more preferably dimethicone.

[0019] In the W / O / W type emulsion of the present invention, the content of silicone oil is not particularly limited, but may be, for example, 0.5% by weight or more, preferably 1% by weight or more, more preferably 1.5% by weight or more, even more preferably 2% by weight or more, and may be 10% by weight or less, preferably 8% by weight or less, more preferably 7% by weight or less, and even more preferably 5% by weight or less, based on the total weight of the W / O / W type emulsion. In one embodiment, the content of silicone oil may be 0.5 to 10% by weight, preferably 1 to 8% by weight, more preferably 1.5 to 7% by weight, and even more preferably 2 to 5% by weight, based on the total weight of the W / O / W type emulsion.

[0020] The W / O / W type emulsion of the present invention contains a water-insoluble powder in the oil phase and / or outer aqueous phase. In this specification, "water-insoluble powder" refers to a component that is solid and powdery at room temperature (25°C) and has a solubility in water at 20°C of 0.1 g / 100 g or less.

[0021] Examples of water-insoluble powders include organic water-insoluble powders such as aluminum starch octenylsuccinate, cellulose, nylon, polyethylene, polymethylsilsesquioxane, silicone elastomers such as (vinyl dimethicone / methicone silsesquioxane) crosspolymer, polymethyl methacrylate, lauroyl lysine, and silk powder; and inorganic water-insoluble powders such as talc, silica, hydrated silica, magnesium silicate, aluminum silicate, sericite, mica, synthetic fluorophlogopite, glass powder, fluorphlogopite, kaolin, clay, bentonite, hectorite, zeolite, bismuth oxychloride, zirconium oxide, magnesium oxide, aluminum oxide, calcium sulfate, barium sulfate, calcium carbonate, and magnesium carbonate. The water-insoluble powder may be one type or two or more types. In one embodiment of the present invention, the water-insoluble powder is preferably an organic water-insoluble powder or an inorganic water-insoluble powder, and more preferably an organic water-insoluble powder. In another embodiment, the water-insoluble powder is preferably at least one selected from the group consisting of aluminum starch octenylsuccinate, talc, silica, and cellulose, and more preferably aluminum starch octenylsuccinate.

[0022] In the W / O / W emulsion of the present invention, the mechanism by which the inclusion of water-insoluble powder in the oil phase and / or outer aqueous phase results in good stability over time is unknown, but it is considered important that the water-insoluble powder exists (is dispersed) as a powder in the W / O / W emulsion of the present invention. In one embodiment of the present invention, the water-insoluble powder is preferably one that can exist as a powder in the aqueous phase, and more preferably one that can exist as a powder in both the aqueous and oil phases. However, it is not necessarily required that all of the water-insoluble powder blended in the W / O / W emulsion of the present invention exists as a powder. In one embodiment, in the W / O / W emulsion of the present invention, it is preferable that at least a portion of the water-insoluble powder exists as a powder, and more preferably all or most of the water-insoluble powder exists as a powder.

[0023] In one embodiment, the water-insoluble powder is preferably insoluble in silicone oil. In this specification, "insoluble in silicone oil" means that the solubility in silicone oil (preferably dimethicone) at 20°C is 0.1 g / 100 g or less. Examples of water-insoluble powders that are insoluble in silicone oil include aluminum starch octenylsuccinate, talc, silica, and cellulose.

[0024] As the water-insoluble powder, the above components may be used as is, or the above components may be subjected to surface treatments such as hydrophobic treatment or hydrophilic treatment.

[0025] The shape of the water-insoluble powder is not particularly limited and may be spherical, rod-shaped, needle-shaped, plate-shaped, irregularly shaped, flake-shaped, spindle-shaped, etc., but it is preferably spherical.

[0026] The average particle size of the water-insoluble powder is not particularly limited, but is preferably 3 to 35 μm, and more preferably 4 to 30 μm. In this specification, the average particle size of the water-insoluble powder refers to the value measured by laser diffraction, Coulter counter, or microscopy.

[0027] In the W / O / W type emulsion of the present invention, the content of water-insoluble powder is not particularly limited, but is preferably 0.05% by weight or more, more preferably 0.1% by weight or more, even more preferably 0.5% by weight or more, and also preferably 5% by weight or less, more preferably 4% by weight or less, and even more preferably 3% by weight or less, based on the total weight of the W / O / W type emulsion. In one embodiment, the content of water-insoluble powder is preferably 0.05 to 5% by weight, more preferably 0.1 to 4% by weight, and even more preferably 0.5 to 3% by weight, based on the total weight of the W / O / W type emulsion.

[0028] In the W / O / W type emulsion of the present invention, when the oil phase contains water-insoluble powder, the content of the water-insoluble powder is not particularly limited, but is preferably 0.05% by weight or more, more preferably 0.1% by weight or more, even more preferably 0.5% by weight or more, and also preferably 3% by weight or less, more preferably 2% by weight or less, and even more preferably 1% by weight or less, based on the total weight of the W / O / W type emulsion. In one embodiment, when the oil phase contains water-insoluble powder, the content of the water-insoluble powder is preferably 0.05 to 3% by weight, more preferably 0.1 to 2% by weight, and even more preferably 0.5 to 1% by weight, based on the total weight of the W / O / W type emulsion.

[0029] In the W / O / W type emulsion of the present invention, the weight ratio of water-insoluble powder to silicone oil (water-insoluble powder / silicone oil) is not particularly limited, but is preferably 0.0625 or higher, more preferably 0.1 or higher, even more preferably 0.3 or higher, and also preferably 3 or lower, more preferably 2 or lower, and even more preferably 1 or lower. In one embodiment, the weight ratio of water-insoluble powder to silicone oil (water-insoluble powder / silicone oil) is preferably 0.0625 to 3, more preferably 0.1 to 2, and even more preferably 0.3 to 1.

[0030] The oil phase may contain oily components other than silicone oil. Other oily components can include liquid oily components and solid oily components. There may be one or more oily components other than silicone oil. The liquid oily components other than silicone oil only need to be liquid at 25°C. Examples of liquid oily components other than silicone oil include natural animal and vegetable oils, hydrocarbon oils, ester oils, higher alcohols, and higher fatty acids, and one or more of these can be used.

[0031] Examples of natural animal and vegetable oils include avocado oil, linseed oil, almond oil, olive oil, cocoa oil, tung oil, wheat germ oil, sesame oil, rice germ oil, rice bran oil, safflower oil, soybean oil, evening primrose oil, camellia oil, corn oil, rapeseed oil, peach kernel oil, palm oil, palm kernel oil, castor oil, sunflower oil, grape oil, jojoba oil, macadamia nut oil, mink oil, cottonseed oil, coconut oil, peanut oil, and rosehip oil.

[0032] Examples of hydrocarbon oils include α-olefin oligomers, squalane, squalene, and liquid paraffin.

[0033] Examples of ester oils include diisobutyl adipate, 2-hexyldecyl adipate, di-2-heptylundecyl adipate, isostearyl isostearate, trimethylolpropane triisostearate, cetyl 2-ethylhexanoate, neopentyl glycol di-2-ethylhexanoate, trimethylolpropane tri-2-ethylhexanoate, pentaerythritol tetra-2-ethylhexanoate, cetyl octanoate, oleyl oleate, octyldodecyl oleate, decyl oleate, and neopentyl glycoside dicaprate. Examples include ethylhexyl succinate, isocetyl stearate, butyl stearate, diisopropyl sebacate, cetyl lactate, tetradecyl lactate, isopropyl myristate, octyldodecyl myristate, cetyl myristate, myristyl myristate, octyl palmitate, ethylhexyl palmitate, hexyldecyl palmitate, heptylundecyl palmitate, phytosteryl oleate, diisostearyl malate, paramethoxycinnamate, pentaerythritol tetralosinate, etc.

[0034] Examples of higher alcohols include octyldodecanol, isostearyl alcohol, and oleyl alcohol.

[0035] Examples of higher fatty acids include isostearic acid, oleic acid, linoleic acid, and linolenic acid. In one embodiment, hydrocarbon oils and ester oils are preferred as liquid oily components other than silicone oil. In one embodiment, squalane and cetyl 2-ethylhexanoate are more preferred as liquid oily components other than silicone oil.

[0036] In the W / O / W type emulsion of the present invention, the content of liquid oily components other than silicone oil is not particularly limited, but is preferably 0.5% by weight or more, more preferably 2% by weight or more, even more preferably 5% by weight or more, and also preferably 40% by weight or less, more preferably 25% by weight or less, and even more preferably 20% by weight or less. In one embodiment, the content of liquid oily components other than silicone oil in the W / O / W type emulsion is preferably 0.5 to 40% by weight, more preferably 2 to 25% by weight, and even more preferably 5 to 20% by weight.

[0037] In the W / O / W type emulsion of the present invention, it is preferable that the oil phase further contains a solid oily component. When the oil phase contains a solid oily component, the time-dependent stability of the W / O / W type emulsion is further improved.

[0038] By including a solid oily component as an oil phase component, the viscosity of the oil phase can be increased and the fluidity of the internal water phase can be reduced. This further improves the stability of the W / O / W type emulsion. The solid oily component only needs to be solid at 25°C. Solid means that it has no fluidity. Semi-solid oily components are also included in the solid oily component. The solid oily component is not particularly limited, but can be selected from solid fats and oils, waxes, hydrocarbons, higher fatty acids, higher alcohols, esters, silicones, etc., with solid fats and oils and waxes being particularly preferred. Examples of solid fats and oils include cocoa butter, coconut oil, palm oil, palm kernel oil, hydrogenated oil, hydrogenated castor oil, Japan wax, and shea butter. Examples of waxes include microcrystalline wax, beeswax, carnauba wax, candelilla wax, and lanolin. Among these, waxes are more preferred as the solid oily component, and microcrystalline wax is even more preferred.

[0039] When a W / O / W type emulsion contains a solid oily component, the content of the solid oily component is not particularly limited, but is preferably, for example, 0.3% by weight or more, more preferably 0.5% by weight or more, and preferably 10% by weight or less, and more preferably 5% by weight or less, in the W / O / W type emulsion. In one embodiment, the content of the solid oily component in the W / O / W type emulsion is preferably 0.3 to 10% by weight, and more preferably 0.5 to 5% by weight. When wax (preferably microcrystalline wax) is used, the content of the wax in the W / O / W type emulsion is preferably 0.4% by weight or more, more preferably 0.5% by weight or more, and preferably 10% by weight or less, and more preferably 5% by weight or less. In one embodiment, when a W / O / W type emulsion contains wax, its content is preferably 0.4 to 10% by weight, and more preferably 0.5 to 5% by weight, in the W / O / W type emulsion.

[0040] In addition, as the oil-phase component, an oil-soluble active ingredient can be optionally contained, and the type thereof is not particularly limited. By further containing an oil-soluble active ingredient, cosmetics having functions derived from the oil-soluble active ingredient can be produced. Further, the W / O / W type emulsion of the present invention can contain a plant extract exemplified below and other cosmetic components as the oil-soluble active ingredient.

[0041] (Outer aqueous-phase component) In the W / O / W type emulsion of the present invention, the outer aqueous phase contains water.

[0042] The W / O / W type emulsion of the present invention contains a water-insoluble powder in the oil phase and / or the outer aqueous phase. It is preferable that the outer aqueous phase of the W / O / W type emulsion of the present invention contains a water-insoluble powder. In the W / O / W type emulsion of the present invention, when the outer aqueous phase contains a water-insoluble powder, the content of the water-insoluble powder is not particularly limited, but it is preferably 0.05% by weight or more, more preferably 0.1% by weight or more, still more preferably 0.5% by weight or more, and preferably 5% by weight or less, more preferably 4% by weight or less, still more preferably 3% by weight or less, based on the total weight of the W / O / W type emulsion. In one aspect, when the outer aqueous phase contains a water-insoluble powder, the content of the water-insoluble powder is preferably 0.05 to 5% by weight, more preferably 0.1 to 4% by weight, still more preferably 0.5 to 3% by weight, based on the total weight of the W / O / W type emulsion.

[0043] The definition, specific examples, shape, average particle size, weight ratio of the water-insoluble powder to silicone oil (water-insoluble powder / silicone oil), etc. of the water-insoluble powder when the outer aqueous phase contains the water-insoluble powder are as described above.

[0044] In the present invention, it is preferable that the outer aqueous phase contains a water-soluble polymer. When the outer aqueous phase contains a water-soluble polymer, the stability over time of the W / O / W type emulsion is further improved. As the water-soluble polymer, a water-soluble polymer known as a thickening agent can be used. Since the water-soluble polymer increases the viscosity of the outer aqueous phase and decreases the fluidity of the W / O type emulsion, it is effective for preventing the aggregation of W / O type emulsions.

[0045] The water-soluble polymer used in the present invention is not particularly limited, and known water-soluble polymers can be used, but examples include natural water-soluble polymers, semi-synthetic water-soluble polymers, and synthetic water-soluble polymers. Examples of natural water-soluble polymers include plant-derived polymers such as arabic gum, guar gum, carrageenan, pectin, agar, quince seed (marmelo), and starch (rice, corn, potato, wheat); microbial polymers such as xanthan gum, dextran, and pullulan; and animal-derived polymers such as collagen, casein, albumin, and gelatin. Examples of semi-synthetic water-soluble polymers include starch-based polymers such as carboxymethyl starch and methylhydroxypropyl starch; water-soluble cellulose-based polymers such as methylcellulose, nitrocellulose, ethylcellulose, hydroxyethylcellulose, hydroxypropylcellulose, and sodium carboxymethylcellulose (CMC); and alginate-based polymers such as sodium alginate and propylene glycol alginate. Examples of synthetic water-soluble polymers include vinyl polymers such as polyvinyl alcohol, polyvinyl methyl ether, and carboxyvinyl polymer (carbomer); copolymer polymers such as polyoxyethylene polyoxypropylene copolymer; acrylic polymers such as sodium polyacrylate, polyacrylamide, alkyl methacrylate copolymer (acrylic acid / alkyl methacrylate copolymer), (sodium acrylate / sodium acryloyldimethyl taurate copolymer), and (acrylates / alkyl acrylate (C10-30)) crosspolymer; polyethyleneimine, cationic polymers, etc. Water-soluble polymers may be used individually or in combination of two or more. Acrylic polymers are preferred as water-soluble polymers, with alkyl methacrylate copolymer and sodium acrylate / sodium acryloyldimethyl taurate copolymer being more preferred. When the W / O / W type emulsion of the present invention contains a water-soluble polymer, its content is, for example, 0.001 to 10% by weight, preferably 0.005 to 5% by weight, and more preferably 0.01 to 2% by weight, in the W / O / W type emulsion.

[0046] The W / O / W emulsion of the present invention may contain components known to contribute to the stability of the emulsion. The W / O / W emulsion of the present invention typically contains a surfactant. The surfactant can be any surfactant used in W / O / W emulsions, and is not particularly limited, but examples include silicone-based surfactants and polyoxyethylene-based surfactants. In one embodiment, the W / O / W emulsion of the present invention preferably contains a silicone-based surfactant. The W / O / W emulsion of the present invention preferably contains a silicone-based surfactant as the W / O surfactant. A W / O surfactant is a surfactant that emulsifies the internal aqueous phase in the oil phase. In one embodiment, the W / O / W emulsion of the present invention preferably has an oil phase that contains a silicone-based surfactant. When the oil phase contains a silicone-based surfactant, the time-dependent stability of the W / O / W emulsion is further improved.

[0047] Silicone-based surfactants are surfactants having a structure in which hydrophilic substituents are introduced into silicone, and by changing the type of hydrophilic substituent, surfactants suitable for various applications can be obtained. In the present invention, there are no particular limitations as long as the surfactant is silicone-based, but for example, polyether-modified silicone-based surfactants with a polyether group substituent are preferred, and polyether-modified silicone-based surfactants having an alkyl group are more preferred. Furthermore, silicone-based surfactants with an HLB value of 7 or less are preferred, those with an HLB value of 6 or less are more preferred, and those with an HLB value of 2.5 to 5.5 are even more preferred. When the HLB value of the silicone-based surfactant is within the above range, an emulsion with better long-term stability can be obtained. The HLB value is a measure that indicates the balance between hydrophilicity and lipophilicity. In this specification, unless otherwise specified, the HLB value refers to the HLB value calculated by the Griffin method.

[0048] Examples of polyether-modified silicone surfactants include PEG-3 dimethicone, PEG-9 methyl ether dimethicone, PEG-10 dimethicone, polysilicone-13, PEG-9 polydimethylsiloxyethyl dimethicone, PEG / PPG-19 / 19 dimethicone, bis(PEG / PPG-14 / 14) dimethicone, (dimethicone / (PEG-10 / 15)) copolymer, cetyl PEG / PPG-10 / 1 dimethicone, lauryl PEG-9 polydimethylsiloxyethyl dimethicone, (PEG-15 / lauryl dimethicone) copolymer, (PEG-15 / lauryl polydimethylsiloxyethyl dimethicone) copolymer, and the like. Examples of polyether-modified silicone surfactants having an alkyl group include lauryl or cetyl dimethicone copolyol, and examples thereof include cetyl PEG / PPG-10 / 1 dimethicone, lauryl PEG-9 polydimethylsiloxyethyl dimethicone, (PEG-15 / lauryl dimethicone) copolymer, (PEG-15 / lauryl polydimethylsiloxyethyl dimethicone) copolymer, and the like. Particularly, cetyl PEG / PPG-10 / 1 dimethicone and lauryl PEG-9 polydimethylsiloxyethyl dimethicone are preferable. The above silicone surfactants may be used alone or in combination of two or more.

[0049] When the W / O / W type emulsion of the present invention contains a silicone surfactant, its content may be, for example, 0.1 to 15% by weight in the W / O / W type emulsion, preferably 0.5 to 12.5% by weight, more preferably 1 to 10% by weight.

[0050] The W / O / W emulsion of the present invention preferably further contains, for example, a polyoxyethylene-based surfactant. The inclusion of a polyoxyethylene-based surfactant further improves the time-dependent stability of the W / O / W emulsion. In one embodiment, the outer aqueous phase may contain a polyoxyethylene-based surfactant. The polyoxyethylene-based surfactant is not particularly limited, but polyoxyethylene sorbitan monooleate or the like can be used. When the W / O / W emulsion of the present invention contains a polyoxyethylene-based surfactant, its content may be, for example, 0.01 to 20% by weight, preferably 0.1 to 10% by weight, and more preferably 1 to 5% by weight, in the W / O / W emulsion.

[0051] In one embodiment, the W / O / W emulsion of the present invention preferably contains a silicone oil in the oil phase and a water-insoluble powder in the outer aqueous phase, and more preferably contains dimethicone in the oil phase and aluminum starch octenylsuccinate in the outer aqueous phase. In another embodiment, the W / O / W emulsion of the present invention preferably contains a silicone oil, a solid oily component and a silicone-based surfactant in the oil phase and a water-insoluble powder in the outer aqueous phase.

[0052] (Other) In addition to the above components, the W / O / W type emulsion of the present invention may appropriately contain various components commonly used in cosmetics, quasi-drugs, pharmaceuticals, fragrances, etc., such as emulsifiers, humectants, thickeners, active ingredients, preservatives, coloring pigments, pH adjusters, UV absorbers, antioxidants, fragrances, etc.

[0053] Furthermore, as described above, the W / O / W type emulsion of the present invention may contain either water-soluble or oil-soluble active ingredients.

[0054] Active ingredients include collagen, hyaluronic acid, elastin, proteoglycans, placenta, astaxanthin, polyphenols, yeast, amino acids, peptides (such as acetyl hexapeptide-8), etc. In addition, plant extracts can be incorporated as active ingredients, such as indigo leaf, red grape, rehmannia glutinosa, hemp seed, angelica tree, adzuki bean, acerola, catechu, avocado, flax, hydrangea, gynostemma pentaphyllum, marsh marigold, arnica, aloe, aloe vera, apricot kernel, strawberry, fig or its leaves, ginkgo leaf, ginkgo nut, rice seed or seed coat, nettle, ylang-ylang, turmeric, mallow, almond, selfheal, plum, or Its pulp, oolong tea, Satsuma mandarin (dried peel), Eleutherococcus senticosus, Rubus parvifolius, Enokitake mushroom, Cassia obtusifolia (cassia seed), elderberry fruit, Sophora japonica (Japanese pagoda tree), Astragalus membranaceus, Coptis japonica, Plantain (Plantago major), Crataegus monogyna (Japanese hawthorn), Snowdrop, Barley, Okra fruit, Panax ginseng, Oenanthe ginseng, Oak, Hypericum perforatum, Hypericum erectum, Lamium album (sequential), Japanese walnut, Lilium lancifolium, Lilium japonicum, Gracilis Lily, Ononis, Elm, Strawberry, Watercress, Watercress, Olive, Oregano, Orange fruit or peel, Rehmannia glutinosa, Cacao seeds, Persimmon or its leaves, Curcuma zedoaria, Oak (Quercus dentata, Oak leaves), Betula japonica or Weeping Betula, Pumpkin, Cattail, Chamomile / Roman chamomile, Guarana seeds, Quince, Garcinia, Willow, Trametes versicolor, Artemisia capillaris, Licorice, Cantha hemp, Canna lily, Rubus parvifolius, Kiwi fruit, Ki Chrysanthemum, Catalpa, Dock, Citrus aurantium, Hedera helix, Aloe vera, Mint, Cinchona, Cinchona tree (Cinchona chinensis, Cinchona japonica), Cabbage, Unripe cabbage, Cucumber, Kumquat fruit, Betel nut, Guava fruit, Guayule, Quercus infectria (gall), Kukui nut, Goji berry (Goji berry, Goji berry fruit, Goji berry leaves, Goji berry bark), Pueraria lobata (Kudzu root), Camphor tree, Gooseberry fruit, Gardenia, Sasa veitchii, Verbena, Sophora flavescens, Cranberry fruit, Chestnut or its inner skin, Grapefruit, Isodon japonicus,Alpinia speciosa (leaves), laurel, gentian, gentian rhizome / root, black tea, golden scutellaria (yellow scutellaria), cranberry, pepper, coffee beans, burdock (burdock root), sesame, sesame grass, schisandra, wheat, rice, rice bran (red bran, white bran), rice oil, hydrolyzed rice extract, konjac, cherry blossoms (Oshima cherry, mountain cherry, Ooyama cherry, Edohigashi, Mamezakura, Miyamazakura, Somei Yoshino, Takanezakura, Kasumizakura, Chojizakura, Kohigan, Satozakura, Kanzakura) leaves, flowers, fruits, and bark (cherry bark), cherries, pomegranates, sweet potatoes, Sato Water lilies, sugar beets, salvia (sage), Japanese pepper, shea (Karite), shiitake mushrooms, asters, perilla (shiso leaves, perilla seeds), linden, field mushrooms, beech mushrooms, white oak mushrooms, meadowsweet, potato, peony, peony root, ginger, sweet flag (acorn, sweet flag root), white iris, white ivy flowers, watermelon, honeysuckle (honeysuckle), stevia, strawberry fruit, horsetail, plum fruit, Scots pine cones, European larch, European ivy, European walnut, European hawthorn Common dandelion, European horse chestnut (marronnier), European pear (fruit, branches), European meadowsweet, European yarrow (millfoil), European rose, European mint / European mint, mallow, water dropwort, celery, angelica tree, gentian, buckwheat seeds, rhubarb, radish, soybean, bitter orange (orange peel, bitter fruit), thyme (wild thyme), damask rose (flower), onion, magnolia, Japanese angelica tree or its root bark, dandelion or white dandelion / Mongolian dandelion, cherry fruit, Korean ginseng (Carrot), evening primrose, camellia, centella asiatica, dayflower, wild bean, Polygonum multiflorum, duberry fruit, winter melon (winter melon seed), chili pepper, angelica tree, marigold, corn or corn silk, Houttuynia cordata, Eucommia ulmoides (Eucommia ulmoides, Eucommia ulmoides leaves), tomato, tormentilla, Chinese yam / Japanese yam, summer orange, jujube, peaches, nandina (Nandina fruit), nutmeg, cinnamon / cassia, chives, garlic, wild rose (fruit), yarrow, wild rose, wild peach, palm, pineapple fruit, basil, lotus (lotus seed,Lotus seeds, parsley, mint (mint leaves), Job's tears (Coix seed), banana, Japanese mint, vanilla beans, papaya, paprika, witch hazel (leaves), rose, iris, Isodon japonicus (longevity grass), water chestnut (water chestnut), cypress, castor bean, sunflower, bell pepper, loquat (loquat leaves), betel nut (betel nut), butterbur, coltsfoot (coltsfoot flowers, coltsfoot leaves), grape fruit or fruit Bark, seeds, leaves, beech, winter licorice, Brazilian licorice, blackberry, plum fruit, blueberry (Vaccinium vitis-idaea), prune, loofah, safflower, berry fruit, Bergenia ligulata (root), spinach, Chinese lantern plant (Physalis root), linden, peony (peony bark), hops, jojoba, maitake mushroom, ephedra, macadamia nut, mulberry (mulberry bark, mulberry leaves), ma Yorana (leaves), mulberry fruit, quince, mango, mangosteen, mandarin fruit, Ganoderma lucidum, green mint, mimosa, Japanese ginger, miracle fruit, soapberry, purple gromwell, purple corn, Melia azadirachta (leaves), lemon balm, sweet clover, melon fruit, peach leaves, fruit, and seeds, bean sprouts, Morello cherry fruit, molokhia, cornflower Examples include cornflower, mint, wild mugwort, eucalyptus, saxifrage, yuzu fruit, lily, European raspberry, mugwort (mugwort leaves), lime fruit, rye, raspberry leaves and fruit, lavender, yellow tea, apple fruit, gentian, lemon fruit, lemongrass, forsythia, Chinese milk vetch, rosemary (rosemary), rosehip (wild rose), wasabi, and burnet.

[0055] Furthermore, other beauty ingredients can also be incorporated, such as Saccharomyces, hydrolyzed conchiolin, hydrolyzed hyaluronic acid, hydroxypropyltrimonium hyaluronate, and hydrolyzed alkyl (C12-13) glyceryl hyaluronate. The appropriate inclusion of these active ingredients in the inner aqueous phase, oil phase, or outer aqueous phase can be determined based on their respective properties.

[0056] The content of each component in each phase relative to the total amount of the W / O / W type emulsion can be appropriately determined depending on the type of active ingredient, surfactant, and the type and amount of solid oil components.

[0057] From the viewpoint of emulsion stability, the weight ratio of the oil phase to the internal aqueous phase (internal aqueous phase / oil phase) is preferably 10 / 90 to 90 / 10, more preferably 20 / 80 to 80 / 20, and even more preferably 25 / 75 to 75 / 25. In one embodiment, the weight ratio of the internal aqueous phase, oil phase and external aqueous phase is preferably 10 to 500 parts by weight, more preferably 20 to 300 parts by weight, and even more preferably 50 to 200 parts by weight of the oil phase per 100 parts by weight of the internal aqueous phase, and preferably 50 to 2000 parts by weight, more preferably 100 to 1500 parts by weight, and even more preferably 200 to 1000 parts by weight of the external aqueous phase.

[0058] The form of the W / O / W type emulsion of the present invention is not particularly limited as long as it has stability over time, but for example, the average particle size of the inner aqueous phase droplets dispersed in the oil phase may be 0.001 to 100 μm, preferably 0.01 to 100 μm, more preferably 0.1 to 100 μm, and the average particle size of the W / O type emulsion dispersed in the outer aqueous phase may be, for example, 0.01 to 100 μm, preferably 0.1 to 100 μm, more preferably 0.5 to 100 μm, and even more preferably 1 to 50 μm.

[0059] The viscosity of the W / O / W type emulsion of the present invention is preferably 17,000 to 50,000 mPa·s at 25°C, more preferably 17,000 to 40,000 mPa·s, and even more preferably 17,000 to 30,000 mPa·s. Here, the viscosity is measured using a BM type viscometer (manufactured by Toki Sangyo Co., Ltd., measurement conditions: rotor No. 4, 12 rpm, 1 minute).

[0060] The W / O / W type emulsion of the present invention can be used in a variety of applications where a W / O / W type emulsion can be applied. In one embodiment, the W / O / W type emulsion of the present invention can be used as a topical preparation (topical composition).

[0061] Topical preparations are those that can be applied to the surface of the body, such as the skin and mucous membranes, and include, for example, cosmetics, quasi-drugs for topical use, pharmaceuticals for topical use, cleansers, and fragrances. As a topical preparation, for example, a skin preparation is preferred.

[0062] The W / O / W emulsion of the present invention can be suitably used, for example, as a topical skin preparation. In this invention, "topical skin preparation" refers to a dosage form that can be administered to the skin, and includes cosmetics such as creams, serums, lotions, toners, and packs, as well as quasi-drugs, pharmaceuticals, cleansers, and fragrances. The form of the topical skin preparation is not particularly limited, but creams or lotions are preferred. When used as a topical skin preparation, its application is not particularly limited as long as it is a known application for which the emulsion can be applied, but cosmetics are preferred, and among these, creams or lotions are even more preferred.

[0063] (Method for producing W / O / W type emulsion) The method for producing a W / O / W type emulsion of the present invention (hereinafter also referred to as the "production method of the present invention") includes the steps of: incorporating a water-insoluble powder into the oil phase and / or outer aqueous phase; preparing a W / O type emulsion by mixing and emulsifying the inner aqueous phase and the oil phase containing silicone oil; and mixing and emulsifying the prepared W / O type emulsion with the outer aqueous phase. The production method of the present invention provides a W / O / W type emulsion of the present invention with good long-term stability.

[0064] In the manufacturing method of the present invention, preferred embodiments of the inner aqueous phase, oil phase, and outer aqueous phase are the same as described above. For example, the oil phase preferably contains a solid oily component and a silicone-based surfactant in addition to silicone oil (preferably dimethicone). The outer aqueous phase preferably contains a water-insoluble powder. The production of a W / O / W type emulsion can preferably be carried out by the following two steps: (1) preparing a W / O type emulsion by mixing and emulsifying the inner aqueous phase with an oil phase containing silicone oil (preferably dimethicone), a solid oily component, and a silicone-based surfactant; and (2) mixing and emulsifying the prepared W / O type emulsion with an outer aqueous phase containing a water-insoluble powder (preferably aluminum starch octenylsuccinate).

[0065] Specifically, an internal aqueous phase is added to an oil phase containing silicone oil, and the mixture is emulsified at an emulsification temperature of preferably 50 to 100°C, more preferably 60 to 95°C, and even more preferably 65 to 85°C to prepare a W / O type emulsion. In this process, the internal aqueous phase and the oil phase are preferably mixed in a weight ratio of internal aqueous phase / oil phase = 10 / 90 to 90 / 10, more preferably 20 / 80 to 80 / 20, and even more preferably 25 / 75 to 75 / 25. The internal aqueous phase may contain other optional components (such as metal salts) that may be used as desired. In addition to silicone oil, the oil phase may contain the above-mentioned optional components (such as oil-soluble active ingredients).

[0066] Next, a W / O type emulsion is added to the outer aqueous phase and emulsified at an emulsification temperature of preferably 70°C or lower, more preferably 0 to 60°C, and even more preferably 10 to 50°C to prepare a W / O / W type emulsion. The outer aqueous phase may contain acrylic polymers such as alkyl acrylate methacrylate copolymer and sodium acrylate / sodium acryloyldimethyl taurate copolymer. The amount of each component added is preferably such that its content in the W / O / W type emulsion falls within the range described above.

[0067] In this specification, a numerical range expressed by a lower limit and an upper limit, i.e., "lower limit to upper limit," includes those lower and upper limits. For example, a range expressed as "1 to 2" means 1 or more and 2 or less, including 1 and 2. In this specification, the upper and lower limits may be any combination of ranges.

[0068] The present invention will be described in detail below based on examples, but the present invention is not limited to these examples.

[0069] The following raw materials were used in the examples and comparative examples below. The HLB values ​​and average particle sizes of the water-insoluble powders listed herein are catalog values ​​provided by the manufacturers.

[0070] (Ingredients) Cetyl PEG / PPG-10 / 1 Dimethicone: Manufactured by Evonik Japan Co., Ltd., HLB value 5.0 Cetyl 2-ethylhexanoate: Manufactured by Nisshin Oillio Group, Ltd. Squalane: Manufactured by Nikko Chemicals Co., Ltd. Microcrystalline wax: Manufactured by Nikko Rica Co., Ltd. Dimethicone: Manufactured by Shin-Etsu Chemical Co., Ltd., KF-96A-10CS Diphenyl dimethicone: Manufactured by Shin-Etsu Chemical Co., Ltd., KF-53 Phenylentrimethicone: Manufactured by Dow Chemical Japan Ltd., DOWSIL (registered trademark) SH 556 Fluid Cyclopentasiloxane: Manufactured by Shin-Etsu Chemical Co., Ltd., KF-995 Aluminum starch octenyl succinate: Manufactured by Nurion Japan Co., Ltd., DRY-FLO (registered trademark) PURE: Average particle size 15 μm (measured by laser diffraction) Talc: Yamaguchi Mica Co., Ltd., Talc CT-250, Average particle size 30 μm (measured by laser diffraction) Silica: AGC SI-TEC Inc., SUNSPHERE® H-51, Average particle size 4.9 μm (measured by Coulter counter) Cellulose: Evonik Japan Co., Ltd., TEGO Feel C 10, Average particle size 30 μm (measured by microscopy) Sodium acrylate / sodium acryloyldimethyl taurate copolymer: SEPPIC S.A. Acrylic acid / alkyl methacrylate copolymer: Lubrizol Advanced Materials, Inc. Polyoxyethylene sorbitan monooleate (20 E.O.): Kao Corporation

[0071] <Examples 1-9> First, each component was mixed according to the mixing ratio (weight %) shown in Table 1 to prepare the oil phase, inner aqueous phase, and outer aqueous phase. Next, the inner aqueous phase was added to the oil phase at a temperature of 80°C and mixed and emulsified to prepare a W / O type emulsion. Then, the W / O type emulsion was added to the outer aqueous phase at a temperature of 50°C and mixed and emulsified to obtain the W / O / W type emulsions (W / O / W type emulsion formulations) of Examples 1-9. When the appearance of the W / O / W type emulsions obtained in Examples 1-9 was visually inspected, they were found to be in an emulsion state. The W / O / W type emulsions obtained in Examples 1-9 were observed with an optical microscope to confirm that W / O / W type emulsions consisting of an inner aqueous phase, oil phase, and outer aqueous phase had been prepared.

[0072] The W / O / W type emulsions of Examples 1 to 9 are W / O / W type emulsions containing silicone oil in the oil phase and water-insoluble powder in the outer aqueous phase.

[0073] <Comparative Examples 1-2> W / O / W type emulsions (W / O / W type emulsion formulations) were prepared in the same manner as in Example 1, except that the composition of each component was as shown in Table 1. The W / O / W type emulsions obtained in Comparative Examples 1-2 had an emulsion-like appearance (visual inspection).

[0074] The W / O / W emulsions of Comparative Examples 1 and 2 are W / O / W emulsions that contain silicone oil in the oil phase and do not contain water-insoluble powders in any of the inner aqueous phase, oil phase, or outer aqueous phase. For Comparative Examples 1 and 2, it was confirmed by optical microscope observation that W / O / W emulsions consisting of an inner aqueous phase, an oil phase, and an outer aqueous phase were successfully prepared.

[0075] The values ​​in Tables 1, 3, and 5 below represent the amount (by weight) of each component in a W / O / W type emulsion (100% by weight).

[0076]

[0077] <Evaluation of W / O / W Emulsions> The stability (properties immediately after preparation and stability over time) of the W / O / W emulsions prepared in each example and comparative example was evaluated according to the following criteria. The results are shown in Table 2.

[0078] [Properties Immediately After Manufacturing] The properties of the W / O / W type emulsion formulations prepared in Examples 1-9 and Comparative Examples 1-2 immediately after manufacturing were examined by visually inspecting the appearance of the formulations at the time of manufacturing (immediately after manufacturing) to check for separation. If there was no separation, 1 mL of the W / O / W type emulsion formulation was added to 50 mL of purified water, and it was visually confirmed whether it dispersed in the purified water. If separation of the aqueous and oil phases of the W / O / W type emulsion occurred, or if the interface of the W / O / W type emulsion broke and the oil phase inverted to the outside of the aqueous phase, it was determined that it did not disperse in the purified water. If the purified water became uniformly cloudy, it was determined that it dispersed in the purified water (no phase inversion), and if the purified water became partially cloudy, it was determined that it dispersed only slightly in the purified water (partial phase inversion). The criteria for judgment are as follows. (Criteria for evaluation) ○: No separation is observed, and it disperses in purified water. △: Partial separation is observed, or it disperses only slightly in purified water. ×: Separation is observed overall, or it does not disperse in purified water.

[0079] [Stability over time] The W / O / W type emulsion formulations prepared in Examples 1-9 and Comparative Examples 1-2 were stored for one month under accelerated conditions at 50°C. Since the viscosity of the W / O / W type emulsion decreases when the interface of the W / O / W type emulsion breaks, the viscosity of the W / O / W type emulsion was used as an indicator of stability over time. High viscosity after storage indicated good stability over time, while low viscosity indicated insufficient stability over time. The viscosity of the W / O / W type emulsion formulations after one month of storage was measured using a BM type viscometer (manufactured by TOKI SANGYO, measurement conditions: rotor No. 4, 12 rpm, 1 minute) and evaluated according to the following criteria. (Criteria for judgment) ○: Viscosity after one month of storage is 17,000 mPa·s or higher △: Viscosity after one month of storage is 10,000 mPa·s or higher and less than 17,000 mPa·s ×: Viscosity after one month of storage is less than 10,000 mPa·s

[0080]

[0081] <Example 10, Comparative Example 3> W / O / W type emulsions (W / O / W type emulsion formulations) were prepared in the same manner as in Example 1, except that the composition of each component was as shown in Table 3. The W / O / W type emulsion of Example 10 is a W / O / W type emulsion containing silicone oil in the oil phase and water-insoluble powder in the outer aqueous phase. The W / O / W type emulsion of Comparative Example 3 is a W / O / W type emulsion containing silicone oil in the oil phase and not containing water-insoluble powder in any of the inner aqueous phase, oil phase, or outer aqueous phase. The W / O / W type emulsions obtained in Example 10 and Comparative Example 3 had an emulsion-like appearance (visual inspection). The W / O / W type emulsions obtained in Example 10 and Comparative Example 3 were observed with an optical microscope to confirm that W / O / W type emulsions consisting of an inner aqueous phase, an oil phase, and an outer aqueous phase had been prepared.

[0082]

[0083] The stability (properties immediately after preparation and stability over time) of the W / O / W type emulsions prepared in Example 10 and Comparative Example 3 was evaluated using the same method as in Example 1. The results are shown in Table 4.

[0084]

[0085] <Examples 11-12, Comparative Examples 4-5> W / O / W type emulsions (W / O / W type emulsion formulations) were prepared in the same manner as in Example 1, except that the formulation of each component was as shown in Table 5. The W / O / W type emulsions of Examples 11-12 are W / O / W type emulsions containing silicone oil and water-insoluble powder in the oil phase. The W / O / W type emulsion of Comparative Example 4 is a W / O / W type emulsion containing silicone oil in the oil phase and not containing water-insoluble powder in any of the inner aqueous phase, oil phase, or outer aqueous phase. The W / O / W type emulsion of Comparative Example 5 is a W / O / W type emulsion containing silicone oil in the oil phase and water-insoluble powder in the inner aqueous phase and not containing water-insoluble powder in any of the oil phase or outer aqueous phase. The W / O / W type emulsions obtained in Examples 11-12 and Comparative Examples 4-5 appeared (visually) as an emulsion. The W / O / W type emulsions obtained in Examples 11-12 and Comparative Examples 4-5 were observed with an optical microscope to confirm that W / O / W type emulsions consisting of an inner aqueous phase, an oil phase, and an outer aqueous phase had been prepared. Table 5 shows the formulation of Example 2, and Table 6 shows the evaluation results of Example 2.

[0086]

[0087] The stability (properties immediately after preparation and stability over time) of the W / O / W type emulsions prepared in Examples 11-12 and Comparative Examples 4-5 was evaluated using the same method as in Example 1. The results are shown in Table 6.

[0088]

[0089] The results in Tables 2, 4, and 6 show that in a W / O / W type emulsion in which the oil phase contains silicone oil, a W / O / W type emulsion with good temporal stability can be obtained by including water-insoluble powder in the oil phase and / or the outer aqueous phase.

[0090] According to the present invention, it is possible to provide a W / O / W type emulsion with good temporal stability despite the oil phase containing silicone oil, and a method for producing the same.

Claims

1. A W / O / W type emulsion comprising an internal aqueous phase, an oil phase, and an external aqueous phase, wherein the oil phase contains silicone oil, and the oil phase and / or the external aqueous phase contains water-insoluble powder.

2. The W / O / W type emulsion according to claim 1, wherein the outer aqueous phase contains water-insoluble powder.

3. The W / O / W emulsion according to claim 1, wherein silicone oil is contained in an amount of 1 to 8% by weight relative to the total weight of the W / O / W emulsion.

4. The W / O / W emulsion according to claim 1, wherein the outer aqueous phase contains 0.5 to 3% by weight of water-insoluble powder relative to the total weight of the W / O / W emulsion.

5. The W / O / W emulsion according to claim 1, wherein the oil phase contains 0.5 to 1% by weight of water-insoluble powder relative to the total weight of the W / O / W emulsion.

6. The W / O / W type emulsion according to claim 1, wherein the weight ratio of water-insoluble powder to silicone oil (water-insoluble powder / silicone oil) is 0.0625 to 3.

7. The W / O / W emulsion according to claim 1, wherein the silicone oil is at least one selected from the group consisting of dimethicone, diphenyldimethicone, phenyltrimethicone, and cyclopentasiloxane.

8. The water-insoluble powder is insoluble in silicone oil, the W / O / W type emulsion according to claim 1.

9. The water-insoluble powder is at least one selected from the group consisting of aluminum starch octenyl succinate, talc, silica, and cellulose, as described in claim 1.

10. The W / O / W emulsion according to claim 1, comprising a silicone-based surfactant.

11. The W / O / W emulsion according to claim 10, wherein the silicone-based surfactant is cetyl PEG / PPG-10 / 1 dimethicone or lauryl PEG-9 polydimethylsiloxyethyl dimethicone.

12. The W / O / W emulsion according to claim 1, wherein the oil phase further contains a solid oily component.

13. The W / O / W type emulsion according to claim 12, wherein the solid oily component is wax.

14. A W / O / W type emulsion according to any one of claims 1 to 13, which is a topical skin preparation.

15. A W / O / W emulsion according to any one of claims 1 to 13, which is a cream or lotion.

16. A method for producing a W / O / W type emulsion, comprising the steps of: incorporating a water-insoluble powder into the oil phase and / or outer aqueous phase; preparing a W / O type emulsion by mixing and emulsifying the inner aqueous phase and the oil phase containing silicone oil; and mixing and emulsifying the prepared W / O type emulsion with the outer aqueous phase.

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