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

Abstract

The present invention provides: a W / O / W-type emulsion that contains betaine, has good temporal stability, and has an excellent in-use feel; and a method for producing the same. The present invention pertains to a W / O / W-type emulsion comprising an inner aqueous phase, an oil phase, and an outer aqueous phase, the W / O / W-type emulsion containing betaine in the inner aqueous phase.

Description

W / O / W emulsion and its manufacturing method

[0001] The present invention relates to a W / O / W emulsion and a method for producing the same. More specifically, the present invention relates to a W / O / W emulsion that contains betaine, has good stability over time, and has an excellent feel when used, and a method for producing the same.

[0002] A W / O / W (water-in-oil-in-water) emulsion is a multiphase emulsion in which a water-in-oil (W / O) emulsion is further emulsified and dispersed in an aqueous phase (external aqueous phase). W / O / W emulsions are known as a formulation technology that can enhance the transdermal absorbability of active ingredients compared to other emulsion types (Non-Patent Document 1), and are expected to be applied to a variety of uses, such as cosmetics, food, and pharmaceuticals.

[0003] On the other hand, betaine (also known as trimethylglycine or glycine betaine) is known to have a moisturizing effect and to suppress stickiness by improving the feel of the skin. Patent Document 1 describes that a lotion containing betaine has a moisturizing effect and is less sticky.

[0004] Japanese Patent Application Publication No. 6-293625

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

[0006] However, Patent Document 1 does not describe a W / O / W emulsion containing betaine.

[0007] Because betaine has the moisturizing effect and texture-improving effect described above, W / O / W emulsions containing betaine are useful, for example, in the field of cosmetics. Therefore, the present inventors conducted research on W / O / W emulsions containing betaine. However, it was found that, although the inclusion of betaine in a W / O / W emulsion increases the moist feeling, the stickiness is not sufficiently reduced, and the stability of the W / O / W emulsion over time decreases, making it more susceptible to separation (phase separation) or phase inversion. Once separation or phase inversion occurs in a W / O / W emulsion, it cannot be restored to its original state.

[0008] An object of the present invention is to provide a W / O / W emulsion containing betaine, which has good stability over time and provides an excellent feeling when used, and a method for producing the same.

[0009] As a result of extensive research, the present inventors have found that by incorporating betaine into the internal aqueous phase of a W / O / W emulsion, it is possible to obtain a W / O / W emulsion that has good stability over time, a moist feeling but reduced stickiness, and an excellent feel when used.

[0010] That is, the present invention relates to the following W / O / W emulsions and methods for producing the same, although the present invention is not limited thereto: [1] A W / O / W emulsion comprising an internal aqueous phase, an oil phase, and an external aqueous phase, wherein the internal aqueous phase contains betaine. [2] The W / O / W emulsion according to [1] above, wherein the betaine content is 0.01 to 5 wt %. [3] The W / O / W emulsion according to [1] or [2] above, wherein the external aqueous phase does not contain betaine. [4] The W / O / W emulsion according to any of [1] to [3] above, wherein the silicone surfactant is cetyl PEG / PPG-10 / 1 dimethicone or lauryl PEG-9 polydimethylsiloxyethyl dimethicone. [5] The W / O / W emulsion according to [4] above, wherein the silicone surfactant is cetyl PEG / PPG-10 / 1 dimethicone or lauryl PEG-9 polydimethylsiloxyethyl dimethicone. [6] The W / O / W emulsion according to any one of [1] to [5] above, wherein the oil phase contains a solid oily component. [7] The W / O / W emulsion according to [6] above, wherein the solid oily component is a wax. [8] The W / O / W emulsion according to any one of [1] to [7] above, which is a skin external preparation. [9] The W / O / W emulsion according to any one of [1] to [8] above, which is a cream or milky lotion.

[10] A method for producing a W / O / W emulsion, comprising the steps of mixing an internal aqueous phase containing betaine with an oil phase and emulsifying the mixture to prepare a W / O emulsion, and mixing the prepared W / O emulsion with an external aqueous phase and emulsifying the mixture.

[0011] According to the present invention, there are provided a W / O / W emulsion containing betaine, which has good stability over time and an excellent feel when used, and a method for producing the same. The W / O / W emulsion of the present invention is useful, for example, as a skin external preparation such as a cosmetic.

[0012] Embodiments of the present invention are exemplified below. (W / O / W Emulsion) The W / O / W emulsion of the present invention is a W / O / W emulsion containing an internal aqueous phase, an oil phase, and an external aqueous phase, and contains betaine in the internal aqueous phase. The W / O / W emulsion of the present invention is typically a W / O / W emulsion containing 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 emulsion of the present invention may be composed of the internal aqueous phase, oil phase, and external aqueous phase. In a W / O / W emulsion, a W / O 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 emulsion of the present invention has good stability over time, i.e., it is less likely to undergo separation or phase inversion over time, and further has an excellent feel when used (it has a moist feeling but is not sticky), and is therefore useful in the field of cosmetics and the like.

[0013] In the present invention, the terms "internal aqueous phase," "oil phase," and "external aqueous phase" may refer to either the respective phases of a W / O / W emulsion or the respective solutions containing the components of each phase used in the production of a W / O / W emulsion.

[0014] (Internal Aqueous Phase Components) In the W / O / W emulsion of the present invention, the internal aqueous phase contains water. The W / O / W emulsion of the present invention contains betaine in the internal aqueous phase. By containing betaine in the internal aqueous phase, the W / O / W emulsion of the present invention has a good feel during use and good stability over time. In the present invention, betaine refers to trimethylglycine. Betaine (trimethylglycine) is an amino acid derivative and an amphoteric compound in which three methyl groups are bonded to the amino group of glycine, forming a salt within the molecule.

[0015] The betaine content in the W / O / W emulsion of the present invention may be 0.005 wt% or more, preferably 0.01 wt% or more, more preferably 0.1 wt% or more, and even more preferably 1 wt% or more. The betaine content in the W / O / W emulsion is preferably 10 wt% or less, more preferably 5 wt% or less, and even more preferably 3 wt% or less. A betaine content within the above range further improves the feel in use and stability over time of the W / O / W emulsion. Therefore, even when the W / O / W emulsion is stored for a long period of time, separation and phase inversion are unlikely to occur, resulting in long-term storage stability. Furthermore, when applied to the skin, the emulsion provides a good moisturizing feeling while minimizing stickiness. In one embodiment, the betaine content in the W / O / W emulsion may be, for example, 0.005 to 10 wt%, preferably 0.01 to 5 wt%, and more preferably 0.1 to 3 wt%.

[0016] The W / O / W emulsion of the present invention preferably contains the above-mentioned amount of betaine in the internal aqueous phase. The betaine content in the internal aqueous phase can be measured by separating the internal aqueous phase, oil phase, and external aqueous phase of the W / O / W emulsion using a known method (e.g., centrifugation), and then measuring the betaine content by a known method (e.g., high-performance liquid chromatography (HPLC)).

[0017] The W / O / W emulsion of the present invention can be used to obtain the effects derived from betaine, such as the moisturizing effect described above.

[0018] The W / O / W emulsion of the present invention preferably further contains a metal salt in the internal aqueous phase. The inclusion of a metal salt as a component of the internal aqueous phase further improves the stability of the W / O / W emulsion over time. While the metal salt is not particularly limited, magnesium sulfate, sodium citrate, amino acid salts such as monosodium glutamate, sodium lactate, and sodium chloride are preferred, with magnesium sulfate being more preferred. One or more metal salts may be used. When the W / O / W emulsion contains a metal salt, the content thereof is not particularly limited, but may be, for example, 0.001 to 10 wt %, preferably 0.01 to 5 wt %, and more preferably 0.1 to 2 wt % in the W / O / W emulsion.

[0019] The internal aqueous phase may contain a water-soluble active ingredient other than betaine, as long as the effects of the present invention are not impaired. The water-soluble active ingredient other than betaine may be one type or two or more types. Examples of water-soluble active ingredients other than betaine include ascorbic acid derivatives (vitamin C derivatives), arbutin, chamomilla ET, placenta extract, rucinol, hydroquinone, etc., which are known as whitening ingredients. Other examples include polyglycerin (e.g., polyglycerin-3, polyglycerin-4, etc.), diglycerin, plant extracts exemplified below, and other cosmetic ingredients.

[0020] When the W / O / W emulsion contains a water-soluble active ingredient other than betaine, the content thereof 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 emulsion. In one embodiment, the content of the water-soluble active ingredient other than betaine in the W / O / W emulsion is also preferably 0.001 to 2% by weight.

[0021] (Oil Phase Component) The oil phase contains an oily component. As the oily component, a liquid oily component or a solid oily component can be used. The oily component may be one type or two or more types. The oil phase usually contains a liquid oily component. The liquid oily component may be any component that is liquid at 25°C. Examples of the liquid oily component include natural animal and vegetable oils, hydrocarbon oils, ester oils, silicone oils, higher alcohols, higher fatty acids, etc., and one or two or more types may be used.

[0022] Examples of natural animal and vegetable oils include avocado oil, linseed oil, almond oil, olive oil, cacao 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, persic 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.

[0023] Examples of hydrocarbon oils include α-olefin oligomers, squalane, squalene, and liquid paraffin.

[0024] 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, neopentyl glycol dicaprate, ethanol, 2-ethylhexyl succinate, isocetyl stearate, butyl stearate, diisopropyl sebacate, cetyl lactate, tetradecyl lactate, isopropyl myristate, octyldodecyl myristate, cetyl myristate, myristyl myristate, octyl palmitate, 2-ethylhexyl palmitate, 2-hexyldecyl palmitate, 2-heptylundecyl palmitate, phytosteryl oleate, diisostearyl malate, para-methoxycinnamate, pentaerythrityl tetrarosinate, and the like.

[0025] Examples of silicone oils include dimethylpolysiloxane, highly polymerized methylpolysiloxane, methylphenylpolysiloxane, methylhydrogenpolysiloxane, octamethylcyclotetrasiloxane, octamethylcyclopentasiloxane, decamethylcyclohexasiloxane, higher alkoxy-modified silicones such as stearoxysilicone, alkyl-modified silicones, and higher fatty acid ester-modified silicones.

[0026] Examples of higher alcohols include octyldodecanol, isostearyl alcohol, and oleyl alcohol.

[0027] Examples of higher fatty acids include isostearic acid, oleic acid, linoleic acid, and linolenic acid. In one embodiment, the liquid oil component is preferably a hydrocarbon oil or an ester oil. In one embodiment, the liquid oil component is more preferably squalane or 2-ethylhexanoate.

[0028] In the W / O / W emulsion of the present invention, the content of the liquid oily component is not particularly limited, but is preferably 0.5% by weight or more, more preferably 2% by weight or more, and even more preferably 5% by weight or more, and is 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 the liquid oily component in the W / O / W 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.

[0029] In the W / O / W emulsion of the present invention, the oil phase preferably contains a solid oil component. When the oil phase contains a solid oil component, the stability of the W / O / W emulsion over time is further improved. Furthermore, the oil phase preferably does not contain betaine.

[0030] By including a solid oily component as the oil phase component, the viscosity of the oil phase can be increased and the fluidity of the internal aqueous phase can be reduced. This can further improve the stability of the W / O / W emulsion. The solid oily component may be solid at 25°C. "Solid" refers to a component that has no fluidity. The solid oily component also includes a semi-solid oily component. The solid oily component is not particularly limited and 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.

[0031] When a W / O / W emulsion contains a solid oily component, the content of the solid oily component is not particularly limited, but is preferably 0.3 wt % or more, more preferably 0.5 wt % or more, and preferably 10 wt % or less, more preferably 5 wt % or less, in the W / O / W emulsion. In one embodiment, the content of the solid oily component in the W / O / W emulsion is preferably 0.3 to 10 wt %, more preferably 0.5 to 5 wt %. When a wax (preferably microcrystalline wax) is used, the content of the wax in the W / O / W emulsion is preferably 0.4 wt % or more, more preferably 0.5 wt % or more, and preferably 10 wt % or less, more preferably 5 wt % or less. In one embodiment, when a W / O / W emulsion contains a wax, the content of the wax in the W / O / W emulsion is preferably 0.4 to 10 wt %, more preferably 0.5 to 5 wt %.

[0032] Furthermore, an oil-soluble active ingredient can be optionally contained as an oil phase component, and the type thereof is not particularly limited. By further containing an oil-soluble active ingredient, for example, it is possible to produce cosmetics that combine the functions derived from betaine and oil-based active ingredients. Furthermore, the W / O / W emulsion of the present invention can contain, as an oil-soluble active ingredient, the plant extracts exemplified below and other cosmetic ingredients.

[0033] (External Aqueous Phase Components) In the W / O / W emulsion of the present invention, the external aqueous phase contains water. In the present invention, the external aqueous phase may contain betaine, but preferably does not contain betaine. This is because the smaller the amount of betaine contained in the external aqueous phase, the more improved the stability of the W / O / W emulsion over time. The amount of betaine contained in the external aqueous phase is preferably 0.5 wt % or less, more preferably 0.3 wt % or less, and even more preferably 0.1 wt % or less in the W / O / W emulsion.

[0034] In the present invention, the external aqueous phase preferably contains a water-soluble polymer. When the external aqueous phase contains a water-soluble polymer, the stability of the W / O / W emulsion over time is further improved. As the water-soluble polymer, a water-soluble polymer known as a thickener can be used. The water-soluble polymer increases the viscosity of the external aqueous phase and reduces the fluidity of the W / O emulsion, and is therefore effective in preventing aggregation of W / O emulsions.

[0035] The water-soluble polymer used in the present invention is not particularly limited, and known water-soluble polymers can be used, including natural water-soluble polymers, semi-synthetic water-soluble polymers, and synthetic water-soluble polymers. Examples of natural water-soluble polymers include plant-based polymers such as arabic gum, guar gum, carrageenan, pectin, agar, quince seed, and starch (rice, corn, potato, and wheat); microbial polymers such as xanthan gum, dextran, and pullulan; and animal-based 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; cellulose-based polymers such as methylcellulose, nitrocellulose, ethylcellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, sodium carboxymethylcellulose (CMC), crystalline cellulose, and cellulose powder; and alginic acid-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, acrylic acid alkyl methacrylate copolymer (acrylic acid / alkyl methacrylate copolymer), (sodium acrylate / sodium acryloyldimethyltaurate) copolymer (sodium acrylate / sodium acryloyldimethyltaurate copolymer), and (acrylates / alkyl acrylate (C10-30)) crosspolymer; polyethyleneimine, cationic polymers, and the like. One type of water-soluble polymer may be used alone, or two or more types may be used in combination. As the water-soluble polymer, an acrylic polymer is preferred, and an acrylic acid alkyl methacrylate copolymer or a sodium acrylate / sodium acryloyldimethyltaurate copolymer is more preferred. When the W / O / W emulsion contains a water-soluble polymer, the content thereof in the W / O / W emulsion 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.

[0036] The W / O / W emulsion of the present invention may contain a component known to contribute to emulsion stability. The W / O / W emulsion of the present invention typically contains a surfactant. The surfactant may be one typically used in W / O / W emulsions, and is not particularly limited, but examples include silicone surfactants and polyoxyethylene surfactants. In one aspect, the W / O / W emulsion of the present invention preferably contains a silicone surfactant. The W / O / W emulsion of the present invention preferably contains a silicone surfactant as the W / O surfactant. The W / O surfactant is a surfactant that emulsifies the internal aqueous phase in the oil phase. In one aspect, the oil phase of the W / O / W emulsion of the present invention preferably contains a silicone surfactant. When the oil phase contains a silicone surfactant, the stability of the W / O / W emulsion over time is further improved.

[0037] Silicone surfactants are surfactants having a structure in which a hydrophilic substituent has been introduced into silicone, and by changing the type of this hydrophilic substituent, surfactants suitable for various applications can be obtained. In the present invention, there are no particular limitations on the silicone surfactant, but for example, polyether-modified silicone surfactants in which the substituent is a polyether group are preferred, and polyether-modified silicone surfactants having an alkyl group are more preferred. Furthermore, silicone surfactants preferably have an HLB value of 7 or less, more preferably 6 or less, and even more preferably 2.5 to 5.5. When the HLB value of a silicone surfactant is within the above range, an emulsion with better stability over time can be obtained. HLB is a measure of the balance between hydrophilicity and lipophilicity. In this specification, the HLB value refers to the HLB value calculated by the Griffin method, unless otherwise specified.

[0038] 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)) crosspolymer, cetyl PEG / PPG-10 / 1 dimethicone, lauryl PEG-9 polydimethylsiloxyethyl dimethicone, (PEG-15 / lauryl dimethicone) crosspolymer, and (PEG-15 / lauryl polydimethylsiloxyethyl dimethicone) crosspolymer. 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) crosspolymer, and (PEG-15 / lauryl polydimethylsiloxyethyl dimethicone) crosspolymer. Cetyl PEG / PPG-10 / 1 dimethicone and lauryl PEG-9 polydimethylsiloxyethyl dimethicone are particularly preferred. The above silicone surfactants may be used alone or in combination of two or more.

[0039] When the W / O / W emulsion contains a silicone surfactant, the content thereof in the W / O / W emulsion may be, for example, 0.1 to 15 wt %, preferably 0.5 to 12.5 wt %, and more preferably 1 to 10 wt %.

[0040] One preferred embodiment of the W / O / W emulsion of the present invention is a W / O / W emulsion in which the internal aqueous phase contains betaine, the oil phase contains a solid oily component and a silicone surfactant, and the external aqueous phase contains a water-soluble polymer. Furthermore, for ease of production, it is preferable that the external aqueous phase does not contain betaine.

[0041] The W / O / W emulsion of the present invention preferably further contains, for example, a polyoxyethylene surfactant. The inclusion of a polyoxyethylene surfactant further improves the stability of the W / O / W emulsion over time. In one embodiment, the external aqueous phase may contain a polyoxyethylene surfactant. The polyoxyethylene surfactant is not particularly limited, but polyoxyethylene sorbitan monooleate, for example, can be used. When the W / O / W emulsion contains a polyoxyethylene surfactant, the content thereof in the W / O / W emulsion may be, for example, 0.01 to 20 wt %, preferably 0.1 to 10 wt %, and more preferably 1 to 5 wt %.

[0042] (Others) In addition to the above-mentioned components, the W / O / W emulsion of the present invention may contain, as appropriate, various components used in ordinary cosmetics, quasi-drugs, pharmaceuticals, and toiletries, such as emulsifiers, moisturizers, thickeners, active ingredients, preservatives, pigments, powders, pH adjusters, ultraviolet absorbers, antioxidants, and fragrances.

[0043] As described above, the W / O / W emulsion of the present invention can contain either a water-soluble or an oil-soluble active ingredient.

[0044] Examples of active ingredients include collagen, hyaluronic acid, elastin, proteoglycan, placenta, astaxanthin, polyphenols, yeast, amino acids, peptides (acetyl hexapeptide-8, etc.), etc. Plant extracts can also be blended as active ingredients, such as indigo leaf, red grape, Rehmannia glutinosa (Rehmannia glutinosa), hemp seed, angelica tree, adzuki bean, acerola, Asa japonica, avocado, flax, hydrangea, Gynostemma pentaphyllum, Altea, arnica, aloe, aloe vera, apricot, strawberry, fig or its leaf, ginkgo biloba (Ginkgo biloba), rice seed or seed coat, nettle, ylang-ylang, turmeric, mallow, marsh mallow, pitcher plant, plum (Japanese plum), or Its pulp, oolong tea, Satsuma mandarin orange (citrus fruit peel), Siberian laurel, Rubus ichigo, Flammulina velutipes, Cassia velutipes (cassia seeds), elderberry fruit, Sophora japonica (sophora flower), Astragalus membranaceus, Coptis chinensis, Plantain (plant psyllium), Crataegus maximowicziana (Japanese hawthorn), Snowdrop, Barley, Okra fruit, Panax ginseng, Carrot, Oak, St. John's wort, St. John's wort, St. John's wort (intermittent), Walnut, Tiger lily, Japanese lily, Columbine Lily, Ononis, Halibut, Dutch strawberry, Dutch mustard (watercress), Dutch watercress, Dutch honeywort, olive, oregano, orange fruit or peel, Rehmannia glutinosa (mature Rehmannia glutinosa), cacao seeds, persimmon or its leaves (persimmon petals), Zedoary, Oak (oak tree, oak leaves), birch or weeping birch, pumpkin, cattail, chamomile, Roman anthem, guarana seeds, Chinese quince, Garcinia cambogia, willow, shiitake mushroom, artemisia capillaris, licorice, hemp, Kanto, canna, bramble, kiwi fruit, kiwi fruit, Chrysanthemum, catalpa, dock, pheasant tree, ivy, aloe arborescens, peppermint, cinchona, cinchona tree (cinchona, red cinchona), cabbage, unripe cabbage fruit, cucumber, kumquat fruit, betel nut, guava fruit, guayule, Quercus infectoria (gall nut), kukui nut, wolfberry (goji, goji berry, goji leaf, ground bone skin), kudzu (kudzu root), camphor tree, gooseberry fruit, gardenia, kumazasa, vervain, sophora japonica, cranberry fruit, chestnut or its astringent skin, grapefruit, black-flowered sedge,Alpinia zerumbet (leaves), Bay tree, Gentian, Gentian rhizome / root, Koucha tea, Scutellaria baicalensis (yellow gong), Cowberry, Pepper, Coffee beans, Burdock (Burdock root, Burdock fruit), Sesame, Schoenanthus orbiculatus, Gomokushi, Wheat, Rice, Rice bran (Red bran, White bran), Rice oil, Hydrolyzed rice extract, Konjac, Cherry leaves, flowers, fruits, and bark (cherry bark) of cherry trees (Oshima cherry, Yamazakura, Ooyamazakura, Edohigashi, Mamezakura, Miyamazakura, Somei-Yoshino, Takanezakura, Kasumizakura, Chojizakura, Kohigan, Satozakura, Kanzakura), Cherry, Pomegranate, Sweet potato, Sato Swallowtail, sugar beet, salvia (sage), Japanese pepper, shea (karite), shiitake mushroom, shion, perilla, green perilla, chirimenjiso, katamenjiso (perilla leaves, perilla seeds), linden, hatakeshimeji, beech-shimeji, white matsutake mushroom, spiraea japonica, potato, peony, peony root, ginger, calamus (iris, calamus root), white iris, white ivy flower, watermelon, honeysuckle (honeysuckle, honeysuckle), stevia, strawberry fruit, horsetail, plum fruit, sylvestris cone, European larch, ivy, walnut, European hawthorn , dandelion, horse chestnut, pear (fruit, branches), meadowsweet, yarrow (milfoil), rose, mint, common mint, mallow, parsley, celery, cnidium, Swertia japonica, buckwheat seeds, rhubarb, radish, soybean, bitter orange (orange peel, zinnia), thyme (thyme, wild thyme, baicalensis), damask rose (flower), onion, magnolia, elm or its root bark, mulberry, dandelion or white flower taraxacum, dandelion, cherry fruit, ginseng (Carrot), evening primrose, camellia, Centella asiatica, dayflower, rice bean, polygonum multiflorum, duberry fruit, wax gourd (winter melon seed), chili pepper, angelica, marigold, corn or corn silk, Houttuynia cordata, ipecac (ipecac root), eucommia (Eucommia ulmoides, Eucommia leaves), tomato, tormentilla, Chinese yam, Japanese yam, citrus fruit, jujube, peanut, Nandina fruit, nutmeg, Cinnamon bark, cinnamon berry, Chinese chive, garlic, wild rose (fruit), yarrow, wild rose, peach, palm, pineapple fruit, basil, lotus (lotus flesh,lotus seeds), parsley (Dutch water parsley), mint (mint, mint leaves), Job's tears (jobi's tears), banana, origanum vulgare, vanilla bean syrup, papaya, paprika, hamamelis (leaf), rose, bean syrup, water chestnut (water chestnut), Japanese cypress, castor, sunflower, bell pepper, loquat (loquat, loquat leaves), betel nut (betel nut peel, betel nut), butterbur, coltsfoot (flowers, leaves), grape berries or fruits Bark, seeds, leaves, beech, Cordyceps sinensis, Brazilian licorice, blackberry, plum fruit, blueberry (Hymenophyllum gracilis), prune, loofah, safflower, berry fruit, Bergenia ligulata (root), spinach, ground cherry (Physalis root), linden tree, peony (peony, peony bark), hops, jojoba, Maitake mushroom, ephedra, macadamia nuts, mulberry (mulberry bark, mulberry leaves), ma Yarrow (leaves), mulberry fruit, quince, mango, mangosteen, mandarin fruit, Ganoderma lucidum, green peppermint, mimosa, ginger, miracle fruit fruit, soapberry, purple root, purple corn, Melia azadirachta (leaves), melissa, melilot, melon fruit, peach leaves, fruit, and seeds, bean sprouts, morello cherry fruit, mulukhiyah, cornflower Examples of herbs include cornflower, monarda, mountain artemisia, eucalyptus, saxifrage, yuzu fruit, lily, European rubus, mugwort (mugwort leaves), lime fruit, rye, raspberry leaves and fruit, lavender, yokucha (green tea), apple fruit, gentian, lemon fruit, lemongrass, forsythia, astragalus, rosemary (romanthus), rose hips (wild rose), wasabi, and burnet.

[0045] Other cosmetic ingredients can also be blended, such as saccharomyces, hydrolyzed conchiolin, hydrolyzed hyaluronic acid, hydroxypropyltrimonium hyaluronate, hydrolyzed alkyl (C12-13) glyceryl hyaluronate, etc. Whether these active ingredients are to be contained in the internal aqueous phase, oil phase, or external aqueous phase can be determined taking into account their respective properties.

[0046] The content of the components in each phase relative to the total amount of the W / O / W emulsion can be determined appropriately depending on the active ingredient, the type of surfactant, the type and amount of the solid oily component, etc.

[0047] 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, relative to 100 parts by weight of the internal aqueous phase, 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 external 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.

[0048] The form of the W / O / W emulsion of the present invention is not particularly limited as long as it has stability over time. 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, and more preferably 0.1 to 100 μm, and the average particle size of the W / O 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.

[0049] The viscosity of the W / O / W emulsion of the present invention is preferably 500 to 50,000 mPa s, more preferably 1,000 to 40,000 mPa s, and even more preferably 2,000 to 30,000 mPa s at 25° C. Here, the viscosity is measured using a BM-type viscometer (manufactured by TOKI SANGYO Corporation, measurement conditions: rotor No. 4, 12 rpm, 1 minute).

[0050] The W / O / W emulsion of the present invention can be used in various applications to which a W / O / W emulsion can be applied. In one embodiment, the W / O / W emulsion of the present invention can be used as an external preparation (external composition).

[0051] External preparations are those that can be applied to body surfaces such as the skin and mucous membranes, and examples thereof include cosmetics, external quasi-drugs, external medicines, cleansers, cosmetics, etc. As external preparations, for example, external preparations for skin are preferred.

[0052] The W / O / W emulsion of the present invention can be suitably used, for example, as a topical skin preparation. The term "topical skin preparation" as used herein refers to a dosage form that can be administered to the skin, and is a general term for cosmetics such as creams, serums, emulsions, lotions, and face packs, as well as quasi-drugs, pharmaceuticals, cleansers, and cosmetic products. The form of the topical skin preparation is not particularly limited, but a cream or emulsion is preferred. When used as a topical skin preparation, its use is not particularly limited as long as it is a known use for which emulsions can be applied, but cosmetics are preferred, and creams or emulsions are even more preferred.

[0053] (Method for Producing W / O / W Emulsion) The method for producing a W / O / W emulsion of the present invention (hereinafter also referred to as the production method of the present invention) comprises the steps of mixing and emulsifying an inner aqueous phase containing betaine with an oil phase to prepare a W / O emulsion, and mixing and emulsifying the prepared W / O emulsion with an outer aqueous phase. The production method of the present invention allows for the production of a W / O / W emulsion of the present invention that has good stability over time and an excellent feel when used.

[0054] In the production method of the present invention, preferred embodiments of the internal aqueous phase, oil phase, and external aqueous phase are the same as those described above. For example, the oil phase preferably contains a solid oily component and a silicone surfactant. The external aqueous phase preferably contains a water-soluble polymer, and more preferably contains a water-soluble polymer and a polyoxyethylene surfactant. The W / O / W emulsion can be preferably produced by the following two steps: (1) mixing and emulsifying an internal aqueous phase containing betaine with an oil phase containing a solid oily component and a silicone surfactant to prepare a W / O emulsion; and (2) mixing and emulsifying the prepared W / O emulsion with an external aqueous phase containing a water-soluble polymer (preferably a water-soluble polymer and a polyoxyethylene surfactant).

[0055] Specifically, an internal aqueous phase containing betaine is added to an oil phase, 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 emulsion. The internal aqueous phase and oil phase are preferably mixed in a weight ratio of internal aqueous phase / oil phase of 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 (e.g., metal salts). The oil phase typically contains a liquid oily component. The oil phase may contain the optional components (e.g., oil-soluble active ingredients) described above.

[0056] Next, the W / O emulsion is added to the external 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 emulsion. The external aqueous phase may contain an acrylic polymer such as an acrylate / alkyl methacrylate copolymer or a sodium acrylate / sodium acryloyldimethyltaurate copolymer. The external aqueous phase preferably does not contain betaine. The amount of each component is preferably such that the content in the W / O / W emulsion falls within the above-mentioned range.

[0057] In this specification, a numerical range expressed by a lower limit and an upper limit, i.e., "lower limit to upper limit," includes the lower limit and the upper limit. For example, a range expressed by "1 to 2" means 1 or more and 2 or less, including 1 and 2. In this specification, the upper limit and the lower limit may be any combination of ranges.

[0058] The present invention will be described in detail below based on examples, but the present invention is not limited to these examples.

[0059] The following raw materials were used in the following examples and comparative examples. The HLB values ​​listed here are values ​​provided in the manufacturer's catalog. Cetyl PEG / PPG-10 / 1 dimethicone: manufactured by Evonik Operations GmbH, HLB 5.0 Squalane: manufactured by Nikko Chemicals Co., Ltd. Microcrystalline wax: manufactured by Nikko Rica Corporation Acrylic acid / alkyl methacrylate copolymer: manufactured by Lubrizol Advanced Materials, Inc. Polyoxyethylene sorbitan monooleate (20 E.O.): manufactured by Kao Corporation 2-Cetyl ethylhexanoate: manufactured by Nisshin Oillio Group, Ltd. Sodium acrylate / sodium acryloyldimethyltaurate copolymer: manufactured by SEPPIC S.A. Betaine: Aminocoat (manufactured by Asahi Kasei Finechem Co., Ltd.)

[0060] Examples 1 to 9: W / O / W emulsions containing betaine were prepared. First, the components were mixed in the proportions (wt %) shown in Table 1 to prepare an oil phase, an inner aqueous phase, and an outer aqueous phase. Next, the inner aqueous phase was added to the oil phase at a temperature of 80°C, and the mixture was mixed and emulsified to prepare a W / O emulsion. The W / O emulsion was then added to the outer aqueous phase at a temperature of 50°C, and the mixture was mixed and emulsified to obtain the W / O / W emulsions (W / O / W emulsion preparations) of Examples 1 to 9. Visual inspection of the appearance of the resulting W / O / W emulsions revealed that they were milky. The resulting W / O / W emulsions were observed under an optical microscope, confirming that W / O / W emulsions consisting of an inner aqueous phase, an oil phase, and an outer aqueous phase had been prepared.

[0061] The W / O / W emulsions of Examples 1 to 6 contain betaine in the internal aqueous phase. The W / O / W emulsions of Examples 7 to 9 contain betaine in both the internal and external aqueous phases. The values ​​in Table 1 indicate the amount (by weight) of each component in the W / O / W emulsion (100% by weight).

[0062] Comparative Examples 1 to 3 W / O / W emulsions (W / O / W emulsion preparations) were prepared in the same manner as in Example 1, except that the components were blended as shown in Table 1. The appearance (visual inspection) of the obtained W / O / W emulsions was milky.

[0063] The W / O / W emulsions of Comparative Examples 1 and 2 are W / O / W emulsions containing betaine in the external aqueous phase. The W / O / W emulsion of Comparative Example 3 is a W / O / W emulsion that does not contain betaine. For Comparative Examples 1 to 3, it was confirmed by optical microscope observation that W / O / W emulsions consisting of an internal aqueous phase, an oil phase, and an external aqueous phase had been prepared.

[0064]

[0065] <Evaluation of W / O / W Emulsions> The W / O / W emulsions prepared in each Example and Comparative Example were evaluated for usability (moist feeling and sticky feeling) and stability (properties immediately after production and stability over time) according to the following criteria. The usability evaluation was performed by two panelists skilled in sensory evaluation. Furthermore, in the evaluation of properties immediately after production and stability over time, emulsions were rated as having low stability if separation of the aqueous and oil phases of the W / O / W emulsion had occurred, or if the interface of the W / O / W emulsion had broken, causing the oil phase to invert to the outside of the outer aqueous phase and no longer disperse in purified water. The results are shown in Table 2.

[0066] [Feeling when used] Each panelist applied each W / O / W emulsion (approximately 1 g, immediately after production and after 2 weeks of storage at 5°C) to an area of ​​2 cm x 2 cm on the skin of their forearm and evaluated the moist feeling and sticky feeling. The moist feeling and sticky feeling were rated on a 5-point scale from 1 to 5 according to the following criteria. The panelists' evaluations were tallied, and the average value was calculated for each W / O / W emulsion, and judged according to the following criteria. (Evaluation criteria for moist feeling) 5 points: Very moist feeling 4 points: Very moist feeling 3 points: Slightly moist feeling 2 points: Very little moist feeling 1 point: No moist feeling (Evaluation criteria for stickiness) 5 points: No stickiness at all 4 points: Almost no stickiness 3 points: Slightly sticky feeling 2 points: Sticky feeling 1 point: Very sticky feeling (Judgment) ○: Higher average value than Comparative Example 3 △: Same average value as Comparative Example 3 ×: Lower average value than Comparative Example 3

[0067] [Properties immediately after production and stability over time] The prepared emulsion formulations were stored under accelerated conditions at 50°C. The appearance of the formulation was visually inspected for separation at the time of production (immediately after production) for properties immediately after production, and after 2 weeks of storage for stability over time. If no separation was found, 1 mL of the emulsion formulation was added to 50 mL of purified water, and visual inspection was performed to determine whether the emulsion formulation dispersed in the purified water. If the purified water became uniformly cloudy, it was evaluated as dispersed (no phase inversion), and if the purified water became partially cloudy, it was evaluated as only slightly dispersed (partial phase inversion). Each evaluation was based on the following criteria. (Evaluation) ◯: No separation was observed and the emulsion dispersed in purified water △: Partial separation was observed, or the emulsion dispersed only slightly in purified water ×: Separation was observed throughout, or the emulsion formulation did not disperse in purified water

[0068]

[0069] The W / O / W emulsions of Comparative Examples 1 and 2, which contained betaine in the external aqueous phase, showed partial or total separation after 2 weeks of storage, and had poor stability over time. Furthermore, they felt more moist than Comparative Example 3, but the stickiness was comparable. On the other hand, the W / O / W emulsions of Examples 1 to 9, which contained betaine in the internal aqueous phase, had better stability over time and a better feel when used than Comparative Examples 1 and 2, which contained betaine in the external aqueous phase.

[0070] It was found that when betaine is incorporated into a W / O / W emulsion, the W / O / W emulsion can be kept stable by incorporating betaine into the internal aqueous phase.

[0071] According to the present invention, it is possible to provide a W / O / W emulsion that contains betaine, has good stability over time, and has an excellent feel when used, and a method for producing the same.

Claims

1. A W / O / W emulsion comprising an internal aqueous phase, an oil phase, and an external aqueous phase, wherein the internal aqueous phase contains betaine.

2. The W / O / W emulsion according to claim 1, wherein the betaine content is 0.01 to 5% by weight.

3. The W / O / W emulsion according to claim 1, wherein the external aqueous phase does not contain betaine.

4. The W / O / W emulsion according to claim 1, which contains a silicone surfactant.

5. The W / O / W emulsion according to claim 4, wherein the silicone surfactant is cetyl PEG / PPG-10 / 1 dimethicone or lauryl PEG-9 polydimethylsiloxyethyl dimethicone.

6. A W / O / W emulsion according to claim 1, wherein the oil phase contains a solid oily component.

7. The W / O / W emulsion according to claim 6, wherein the solid oily component is a wax.

8. The W / O / W emulsion according to any one of claims 1 to 7, which is an external preparation for the skin.

9. The W / O / W emulsion according to any one of claims 1 to 7, which is a cream or a milky lotion.

10. A method for producing a W / O / W emulsion, comprising: a step of mixing an inner aqueous phase containing betaine with an oil phase and emulsifying the mixture to prepare a W / O emulsion; and a step of mixing the prepared W / O emulsion with an outer aqueous phase and emulsifying the mixture.

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