Water-in-oil emulsion composition

Abstract

A water-in-oil emulsion composition containing (a) at least one ascorbic acid phosphate ester compound selected from the group consisting of ascorbic acid phosphate esters and salts thereof, (b) an organic modified clay mineral, (c) an oily agent, and (d) water, wherein the component (b) content is 0.2-4.5 mass%.

Description

[Technical field]

[0001] The present invention relates to a water-in-oil emulsion composition. This application claims priority based on Japanese Patent Application No. 2019-145509, filed on August 7, 2019, the contents of which are incorporated herein by reference. [Background technology]

[0002] Ascorbic acid phosphate and its salts are transferred to the skin and converted to ascorbic acid, promoting collagen synthesis. In addition, ascorbic acid phosphate and its salts inhibit the activity of matrix metalloproteinase (MMP), thereby suppressing collagen decomposition. Due to this function, ascorbic acid phosphate and its salts have a very useful effect on the skin. Therefore, ascorbic acid phosphate and its salts are widely used as ingredients in external skin preparations such as cosmetics, but they are unstable in aqueous solutions and are prone to problems such as crystal precipitation and discoloration, especially when used at high concentrations.

[0003] For this reason, a method of blending ascorbic acid derivatives in the aqueous phase of a water-in-oil emulsion composition has been attempted. For example, Patent Document 1 describes a water-in-oil emulsion composition containing a partially crosslinked polyether-modified organopolysiloxane polymer, silicone oil, ascorbic acids, and water. Patent Document 2 describes a water-in-oil emulsion composition containing an ascorbic acid derivative, liquid cyclic dimethylpolysiloxane, a polysaccharide fatty acid ester, and water. In this way, most of the water-in-oil emulsion compositions that blend ascorbic acid derivatives at high concentrations have their oily components limited to silicone oil.

[0004] In addition, various thickeners have been selected to impart high viscosity to water-in-oil emulsion compositions. However, when an ionic thickener is used in a system containing ascorbic acid derivatives, the viscosity decreases due to the influence of electrolytes. On the other hand, even when a non-ionic thickener, which is less susceptible to electrolytes, is used, a high thickening effect cannot be expected, and it does not contribute sufficiently to the stability of the formulation. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2004-339106 A [Patent Document 2] JP 2007-204399 A Summary of the Invention [Problem to be solved by the invention]

[0006] As described above, the water-in-oil emulsion composition containing ascorbic acid derivatives does not have sufficient emulsion stability, as crystals of the ascorbic acid derivatives in the composition precipitate over time, etc. This problem is particularly noticeable when the water-in-oil emulsion composition contains a high concentration of ascorbic acid derivatives. Therefore, an object of the present invention is to provide a water-in-oil emulsion composition which contains an ascorbic acid phosphate and / or a salt thereof and is capable of suppressing the precipitation of crystals over time. [Means for solving the problem]

[0007] The present invention includes the following aspects. [1] A water-in-oil type emulsion composition comprising: (a) at least one ascorbic acid phosphate compound selected from the group consisting of ascorbic acid phosphate esters and their salts; (b) an organically modified clay mineral; (c) an oiliness agent; and (d) water, wherein the content of component (b) is 0.2 to 4.5% by mass. [2] The water-in-oil emulsion composition according to [1], wherein the component (a) is a magnesium salt of ascorbic acid phosphate. [3] The water-in-oil emulsion composition according to [1] or [2], wherein the content of the component (a) is 0.5 to 20 mass %. [4] The water-in-oil emulsion composition according to any one of [1] to [3], further comprising (e) at least one thickener selected from the group consisting of natural polymers and cellulose-based polymers. [5] The water-in-oil emulsion composition according to [4], wherein the component (e) is xanthan gum, gellan gum or hydroxyethyl cellulose. [6] The water-in-oil emulsion composition according to [4] or [5], wherein the content of the component (e) is 0.01 to 1 mass %. [7] The water-in-oil emulsion composition according to any one of [1] to [6], wherein the component (b) is an organically modified hectorite. [8] The water-in-oil emulsion composition according to [7], wherein the organically modified hectorite is disteardimonium hectorite or quaternium-18 hectorite. [9] The water-in-oil emulsion composition according to any one of [1] to [8], wherein the content of the component (d) is 50 to 90 mass %.

[10] The water-in-oil emulsion composition according to any one of [1] to [9], wherein the mass ratio of the component (c) to the component (d) is (c):(d)=1:2 to 1:10.

[11] The water-in-oil emulsion composition according to any one of [1] to

[10] , which has a viscosity measured at 25°C of 9 to 50 Pa s.

[12] The water-in-oil emulsion composition according to any one of [1] to

[11] , which is a cosmetic. Effect of the Invention

[0008] The present invention provides a water-in-oil emulsion composition that contains ascorbic acid phosphate and / or its salt as an active ingredient and can suppress crystal precipitation over time, and also provides a water-in-oil emulsion composition that has excellent emulsion stability even when it contains a high concentration of ascorbic acid phosphate and / or its salt. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] In one embodiment, the present invention provides a water-in-oil emulsion composition. The water-in-oil emulsion composition of this embodiment contains at least the following components (a) to (d). The content of the following component (b) is 0.2 to 4.5% by mass relative to the total mass (100% by mass) of the water-in-oil emulsion composition. (a) at least one ascorbic acid phosphate compound selected from the group consisting of ascorbic acid phosphate esters and salts thereof; (b) Organically modified clay minerals (c) Oily agent (d) water

[0010] In this specification, the term "water-in-oil emulsion composition" refers to an emulsion composition in which the dispersed phase (phase dispersed as droplets) is water and the continuous phase (outer phase) is oil, and is also called a water-in-oil emulsion (w / o emulsion). The water-in-oil emulsion composition can be suitably used as a formulation for cosmetics and the like.

[0011] [Component (a)] The component (a) is at least one selected from the group consisting of ascorbic acid phosphate and its salts. Ascorbic acid phosphate is a compound in which a phosphate group is introduced into the hydroxy group of ascorbic acid. Ascorbic acid phosphate and its salts have been confirmed to exhibit excellent functions on the skin, such as whitening effect, active oxygen removal effect, and improvement effect on skin damage such as acne, wounds, and burns. Therefore, by blending ascorbic acid phosphate and / or its salt, the above-mentioned effects can be imparted to the water-in-oil emulsion composition.

[0012] The ascorbic acid phosphate in component (a) can be a compound represented by the following general formula (1): The compound represented by the following general formula (1) is ascorbic acid-2-phosphate in which the hydroxyl group at the 2-position of ascorbic acid is protected by a phosphate ester.

[0013] [ka]

[0014] Ascorbic acid phosphate exists in D-, L- and DL-isomers. The ascorbic acid phosphate in component (a) may be any of these stereoisomers, but is preferably the L-isomer.

[0015] The salt of ascorbic acid phosphate in component (a) is not particularly limited, but examples include salts with inorganic bases and salts with organic bases. Examples of salts with inorganic bases include alkali metal salts such as sodium salts and potassium salts; alkaline earth metal salts such as calcium salts and magnesium salts; aluminum salts; ammonium salts; zinc salts; and the like. Examples of salts with organic bases include alkylammonium salts and salts with basic amino acids.

[0016] Among the above, the salt of ascorbic acid phosphate in component (a) is preferably an alkali metal salt or an alkaline earth metal salt, more preferably a sodium salt or a magnesium salt, and even more preferably a magnesium salt. The magnesium salt of ascorbic acid phosphate has the advantage of being highly stable and resistant to coloration.

[0017] Preferred embodiments of the ascorbic acid phosphate in component (a) include alkali metal salts (e.g., sodium salts) of the compound represented by the above general formula (1) and alkaline earth metal salts (e.g., magnesium salts) of the compound represented by the above general formula (1).

[0018] Sodium salt of L-ascorbic acid 2-phosphate ester is commercially available from Showa Denko KK under the product name Ascorbic Acid PS (display name: Sodium Ascorbyl Phosphate). Magnesium salt of L-ascorbic acid 2-phosphate is commercially available from Showa Denko KK under the product name Ascorbic Acid PM (display name: Magnesium Ascorbyl Phosphate). The ascorbic acid PS and the ascorbic acid PM are exemplified as preferred examples of component (a).

[0019] The component (a) may be one selected from the group consisting of ascorbic acid phosphate and its salts, or two or more may be used in combination. The component (a) preferably contains a salt of ascorbic acid phosphate, and more preferably uses an alkali metal salt (e.g., sodium salt) or an alkaline earth metal salt (e.g., magnesium salt) of ascorbic acid phosphate alone.

[0020] The content of the (a) component in the water-in-oil emulsion composition of this embodiment is not particularly limited, but is preferably 0.5 to 20% by mass relative to the total mass (100% by mass) of the water-in-oil emulsion composition. When the content of the (a) component is 0.5% by mass or more, the functions of the ascorbic acid phosphate or its salt (skin whitening effect, active oxygen scavenging effect, etc.) are easily exhibited. When the content of the (a) component is 20% by mass or less, it is easy to achieve a balance with other components. When the (a) component contains two or more selected from the group consisting of ascorbic acid phosphate and its salt, the content of the (a) component refers to the total content of these.

[0021] The content of component (a) in the water-in-oil emulsion composition of this embodiment is more preferably 1 to 18% by mass, further preferably 2 to 15% by mass, and particularly preferably 3 to 12% by mass. As shown in the examples described later, the content of component (a) in the water-in-oil emulsion composition of this embodiment can be 5% by mass or more, 7% by mass or more, or 9% by mass or more. In conventional preparations, when ascorbic acid phosphate and / or a salt thereof is blended at a high concentration (e.g., 3% by mass or more), crystals are precipitated during storage, causing problems such as adhesion to the lid or edge of the container. On the other hand, in the water-in-oil emulsion composition of the present embodiment, even when ascorbic acid phosphate and / or a salt thereof is blended at a high concentration (e.g., 3% by mass or more), the precipitation of crystals is suppressed, and excellent emulsion stability can be maintained.

[0022] Ascorbic acid phosphate or a salt thereof can be produced by known production methods, for example, the methods described in JP-A-2-279690 and JP-A-6-345786. For example, ascorbic acid can be phosphorylated by reacting it with phosphorus oxychloride or the like to obtain a salt of ascorbic acid phosphate. The obtained ascorbic acid phosphate can be neutralized with a metal oxide such as magnesium oxide, a metal hydroxide such as sodium hydroxide, or the like to obtain a salt of ascorbic acid phosphate.

[0023] [(b) Component] Component (b) is an organically modified clay mineral. By blending component (b), a stable emulsified state can be obtained. In the water-in-oil emulsion composition of this embodiment, it is presumed that the organically modified clay mineral gels the oil phase, which is the continuous phase (outer phase), and inhibits the coalescence of the aqueous phase, which is the dispersed phase, thereby maintaining a stable emulsified state.

[0024] Organically modified clay minerals are water-swellable clay minerals (e.g., montmorillonite, saponite, hectorite, bentonite, etc.) in which the convertible cations present between the crystal layers have been replaced with organic cationic compounds (e.g., cationic surfactants such as quaternary ammonium salts).

[0025] The organically modified clay mineral to be blended in the water-in-oil emulsion composition of the present embodiment is not particularly limited as long as it is a component that is generally used in cosmetics, etc. As the organically modified clay mineral, a clay mineral such as montmorillonite, saponite, hectorite, bentonite, beidellite, nontronite, vermiculite, laponite, etc., which has been treated with a cationic surfactant such as a quaternary ammonium salt, can be used. Examples of quaternary ammonium salts used in the organic modification treatment of clay minerals include alkyltrimethylammonium chloride (e.g., stearyltrimethylammonium chloride), dialkyldimethylammonium chloride (e.g., distearyldimethylammonium chloride), and benzalkonium chloride (e.g., stearyldimethylbenzylammonium chloride).

[0026] Specific examples of organically modified clay minerals include organically modified hectorites such as disteardimonium hectorite, quaternium-18 hectorite, and stearalkonium hectorite; and organically modified bentonites such as quaternium-18 bentonite. It is preferable to use organically modified hectorite. Among the above, from the viewpoint of affinity with the oily agent described later, it is preferable to use disteardimonium hectorite or quaternium-18 hectorite, and it is more preferable to use disteardimonium hectorite.

[0027] The organically modified clay mineral may be any commercially available product without particular limitation. The organically modified clay mineral may be a premix product dissolved in an oil agent. Examples of commercially available products containing disteardimonium hectorite include NIKKOL (registered trademark) NIKKOL NIKOMULUS (registered trademark) WO, NIKKOL NIKOMULUS WO-CF, NIKKOL NIKOMULUS WO-CF PLUS, and NIKKOL NIKOMULUS WO-NS (all manufactured by Nikko Chemicals Co., Ltd.). Examples of commercially available products containing quaternium-18 hectorite include Sumecton (registered trademark)-SAN and Sumecton-SAN-P (all manufactured by Kunimine Kogyo Co., Ltd.). The organically modified clay minerals may be used alone or in combination of two or more kinds.

[0028] The content of component (b) in the water-in-oil emulsion composition of this embodiment is 0.2 to 4.5% by mass relative to the total mass (100% by mass) of the water-in-oil emulsion composition. When the content of component (b) is 0.2% by mass or more, the precipitation of crystals of ascorbic acid phosphate and / or its salt is suppressed, and a stable emulsified state can be maintained. When the content of component (b) is 4.5% by mass or less, it is easy to balance with other components, and it is possible to prepare a water-in-oil emulsion composition. The content of component (b) in the water-in-oil emulsion composition of this embodiment is preferably from 0.3 to 3.5 mass %, more preferably from 0.4 to 2.5 mass %, and even more preferably from 0.5 to 1.5 mass %.

[0029] [(c) component] The component (c) is an oily agent. The component (c) forms an oil phase in the water-in-oil emulsion composition of this embodiment. The oily agent is a so-called oil (oily substance) and forms a water-in-oil emulsion together with the water of the component (d). In addition, by including the oily agent as the component (c), the feel of the preparation such as a cosmetic becomes more desirable when used.

[0030] The type of oily agent is not particularly limited, and for example, silicone oil, ester oil, vegetable oil, hydrocarbon oil, etc. The oily agent may be used alone or in combination of two or more kinds. The water-in-oil emulsion composition of the present embodiment preferably contains ester oil, vegetable oil, and hydrocarbon oil as oily agents. The blending ratio of these oily agents can be appropriately set according to the desired feeling of use. The blending amount of silicone oil in component (c) can be, for example, 1 to 20 mass%, 3 to 15 mass%, or 5 to 12 mass% relative to the total mass (100 mass%) of component (c). The blending amount of ester oil in component (c) can be, for example, 40 to 75 mass%, 50 to 70 mass%, or 55 to 65 mass% relative to the total mass (100 mass%) of component (c). The blending amount of vegetable oil in component (c) can be, for example, 1 to 20 mass%, 3 to 15 mass%, or 5 to 13 mass% relative to the total mass (100 mass%) of component (c). The amount of hydrocarbon oil in component (c) can be, for example, 10 to 40 mass %, 15 to 35 mass %, or 20 to 30 mass % relative to the total mass (100 mass %) of component (c).

[0031] In the past, in the water-in-oil emulsion composition containing ascorbic acid phosphate and / or its salt, the type of oily agent that can be blended is often limited to silicone oil.In the water-in-oil emulsion composition of the present embodiment, the type of oily agent is not limited to silicone oil, and silicone oil, ester oil, vegetable oil, hydrocarbon oil, etc. can be blended in appropriate combination according to the purpose of the formulation and the desired feeling of use of the formulation.

[0032] Specific examples of silicone oils include dimethylpolysiloxane (dimethicone), cyclopentasiloxane, methylphenylpolysiloxane, methylhydrogenpolysiloxane, octamethylcyclotetrasiloxane, decamethylcyclopentasiloxane, dodecamethylcyclohexasiloxane, tetramethyltetrahydrogencyclotetrasiloxane, stearoxysilicone, etc. Among these, it is preferable to use dimethylpolysiloxane or cyclopentasiloxane, since it provides a relatively light feel as a formulation of cosmetics, etc. Silicone oils can be used without any particular restrictions on commercially available products.

[0033] Specific examples of ester oils include isodecyl neopentanoate, isocetyl octanoate, isononyl isononanoate, isodecyl isononanoate, tridecyl isononanoate, hexyl laurate, 2-hexyldecyl laurate, caprylyl laurate, isopropyl myristate, isocetyl myristate, isotridecyl myristate, 2-octyldodecyl myristate, isopropyl palmitate, 2-ethylhexyl palmitate, isooctyl palmitate, isocetyl palmitate, isodecyl palmitate, isostearyl palmitate, 2-octyldecyl palmitate, isopropyl isostearate, 2-octyldodecyl stearate, isostearyl isostearate, 2-octyldodecyl erucate, etc. Among these, isodecyl neopentanoate or caprylyl laurate is preferably used because it provides a relatively light feel when used in preparations such as cosmetics. As the ester oil, commercially available products can be used without particular limitation.

[0034] Specific examples of vegetable oils include coconut oil, palm oil, palm kernel oil, safflower oil, olive oil, castor oil, jojoba oil, avocado oil, sesame oil, tea oil, evening primrose oil, wheat germ oil, macadamia nut oil, almond oil, hazelnut oil, kukui nut oil, rosehip oil, meadowfoam oil, persic oil, tea tree oil, peppermint oil, corn oil, rapeseed oil, sunflower oil, wheat germ oil, linseed oil, cottonseed oil, soybean oil, peanut oil, rice bran oil, cacao butter, shea butter, hydrogenated coconut oil, hydrogenated castor oil, hydrogenated jojoba oil, etc. Among these, palm oil, olive oil, jojoba oil, avocado oil, macadamia nut oil, kukui nut oil, or meadowfoam oil is preferably used because it is easily available. As for vegetable oils, commercially available products can be used without any particular restrictions.

[0035] Specific examples of the hydrocarbon oil include liquid paraffin, heavy liquid isoparaffin, light liquid isoparaffin, α-olefin oligomer, polyisobutene, hydrogenated polyisobutene, polybutene, squalane, olive-derived squalane, squalene, petrolatum, solid paraffin, etc. Among these, squalane or liquid paraffin is preferably used because it provides a relatively light feel as a formulation for cosmetics and the like. As the hydrocarbon oil, commercially available products can be used without particular restrictions.

[0036] When the (c) component contains an ester oil, a vegetable oil, and a hydrocarbon oil, specific examples of combinations include, for example, caprylyl laurate and isodecyl neopentanoate as the ester oil; at least one selected from the group consisting of palm oil, olive oil, jojoba oil, avocado oil, macadamia nut oil, kukui nut oil, and meadowfoam oil (preferably kukui nut oil) as the vegetable oil; and at least one selected from the group consisting of squalane and liquid paraffin (preferably squalane) as the hydrocarbon oil.

[0037] The content of component (c) in the water-in-oil emulsion composition of this embodiment is preferably 5 to 30% by mass relative to the total mass (100% by mass) of the water-in-oil emulsion composition. When the content of component (c) is within the above-mentioned preferred range, it is easy to adjust the feel of use of preparations such as cosmetics. The content of component (c) in the water-in-oil emulsion composition of this embodiment is more preferably 10 to 25% by mass, and even more preferably 10 to 20% by mass.

[0038] In the water-in-oil emulsion composition of this embodiment, the ratio (mass ratio) of the oily agent, component (c), to water, component (d), is preferably (c):(d)=1:2 to 1:10, and more preferably (c):(d)=1:4 to 1:6. When the ratio of component (c) to component (d) is within the above-mentioned preferred range, the ratio of the dispersed phase to the continuous phase becomes appropriate, and it becomes possible to efficiently increase the viscosity of the water-in-oil emulsion composition.

[0039] [(d) component] The component (d) is water. The water may be of a grade that can be used in cosmetics, such as purified water. The component (d) forms the water phase in the water-in-oil emulsion composition of this embodiment. The component (d) is also used as a solvent for dissolving or mixing the component (a) and other optional components described below.

[0040] The content of component (d) is the remainder of the total amounts of the above components (a) to (c) and other optional components described below. The content of component (d) in the water-in-oil emulsion composition of this embodiment is preferably 50 to 90% by mass relative to the total mass (100% by mass) of the water-in-oil emulsion composition. When the content of component (d) is within the above-mentioned preferred range, water-soluble components are easily dissolved. The content of component (d) in the water-in-oil emulsion composition of this embodiment is more preferably 55 to 85% by mass, further preferably 60 to 80% by mass, and particularly preferably 65 to 75% by mass.

[0041] [Other ingredients] The water-in-oil emulsion composition of the present embodiment may contain other optional components in addition to the above components (a) to (d), such as a thickener, a surfactant, an emulsifying aid, and a preservative.

[0042] (Thickener: component (e)) The water-in-oil emulsion composition of this embodiment preferably contains at least one thickener selected from the group consisting of natural polymers and cellulose-based polymers (hereinafter, sometimes referred to as "component (e)"). When component (e) is blended in the water-in-oil emulsion composition of this embodiment, a more stable emulsified state can be obtained, which is preferable. It is presumed that component (e) contributes to stabilizing the emulsified state by increasing the viscosity of the aqueous phase, which is the dispersed phase.

[0043] The natural polymer is a polymer that exists in nature, and examples thereof include polysaccharides, peptides, proteins, and nucleic acids. The natural polymer used as component (e) is preferably a polysaccharide, peptide, or protein. Specific examples of the natural polymer include xanthan gum, tamarind gum, locust bean gum, gellan gum, carrageenan, guar gum, gum arabic, agar, karaya gum, tragacanth gum, starch, alginic acid, alginates (e.g., sodium alginate), dextran, dextrin, amylose, gelatin, collagen, pullulan, pectin, amylopectin, starch, chitin, albumin, and casein. Among these, xanthan gum, tamarind gum, locust bean gum, gellan gum, carrageenan, guar gum, gum arabic, agar, karaya gum, or tragacanth gum is preferred, and xanthan gum or gellan gum is more preferred, since a high thickening effect can be expected with a relatively small amount.

[0044] The cellulose-based polymer is a compound in which a part of the hydroxyl groups of cellulose is replaced by another functional group. Specific examples of the cellulose-based polymer include methyl cellulose, ethyl cellulose, propyl cellulose, ethyl methyl cellulose, carboxymethyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, and hydroxypropyl methyl cellulose. Among these, since they are nonionic, methyl cellulose, ethyl cellulose, propyl cellulose, ethyl methyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, and hydroxypropyl methyl cellulose are preferred, and hydroxyethyl cellulose is more preferred.

[0045] The thickener may be any commercially available thickener without any particular limitations. Examples of commercially available xanthan gum include KELTROL (registered trademark) CG-SFT (manufactured by CP Kelco). Examples of commercially available gellan gum include KELCOGEL (registered trademark) CG-LA (manufactured by CP Kelco). Examples of commercially available hydroxyethyl cellulose include HEC Daicel SE550 (manufactured by Daicel FineChem Co., Ltd.). The thickener may be one selected from the group consisting of natural polymers and cellulosic polymers, or two or more of them may be used in combination.

[0046] The content of component (e) in the water-in-oil emulsion composition of this embodiment is preferably 0.01 to 1 mass% relative to the total mass (100 mass%) of the water-in-oil emulsion composition. When the content of component (e) is within the above-mentioned preferred range, the viscosity of the aqueous phase, which is the dispersed phase, can be sufficiently increased. The content of component (e) in the water-in-oil emulsion composition of this embodiment is more preferably 0.02 to 0.8 mass%, and even more preferably 0.05 to 0.5 mass%.

[0047] When component (e) is a natural polymer such as xanthan gum or gellan gum, the content of component (e) of 0.08 to 0.5% by mass is particularly preferred since this can inhibit yellowing of the water-in-oil emulsion composition. When component (e) is a cellulose-based polymer such as hydroxyethyl cellulose, the content of component (e) is particularly preferably 0.12 to 0.5% by mass, which can inhibit yellowing of the water-in-oil emulsion composition.

[0048] (Surfactant: component (f)) The water-in-oil emulsion composition of the present embodiment preferably contains a surfactant (hereinafter, sometimes referred to as "component (f)"). When the water-in-oil emulsion composition contains component (f), the organically modified clay mineral, which is component (b), forms a complex with component (f), and an oil gel can be constructed.

[0049] The type of surfactant is not particularly limited, and for example, polyglycerin fatty acid ester, sorbitan fatty acid ester, sucrose fatty acid ester, etc. can be used. Among these, polyglycerin fatty acid ester is preferred because it can increase the viscosity of the water-in-oil emulsion composition more efficiently with a small amount. The surfactant may be used alone or in combination of two or more kinds.

[0050] Specific examples of polyglycerin fatty acid esters include polyglyceryl-2 stearate, polyglyceryl-3 stearate, polyglyceryl-4 stearate, polyglyceryl-5 stearate, polyglyceryl-6 stearate, polyglyceryl-8 stearate, polyglyceryl-10 stearate, polyglyceryl-6 distearate, polyglyceryl-10 distearate, polyglyceryl-2 tristearate, polyglyceryl-10 decatenate, polyglyceryl-2 isostearate, polyglyceryl-3 isostearate, polyglyceryl-4 isostearate, polyglyceryl-5 isostearate, polyglyceryl-6 isostearate, polyglyceryl-8 isostearate, and polyglyceryl-10 isostearate. Polyglyceryl-10, diisostearate polyglyceryl-2, diisostearate polyglyceryl-3, diisostearate polyglyceryl-10, triisostearate polyglyceryl-2, tetraisostearate polyglyceryl-2, decaisostearate polyglyceryl-10, oleate polyglyceryl-2, oleate polyglyceryl-3, oleate polyglyceryl-4, oleate polyglyceryl-5, oleate polyglyceryl-6, oleate polyglyceryl-8, oleate polyglyceryl-10, dioleate polyglyceryl-6, trioleate polyglyceryl-2, decaoleate polyglyceryl-10, polyricinoleate polyglyceryl-6, polyricinoleate polyglyceryl-10, and the like. Among these, polyglyceryl-2 isostearate or polyglyceryl-6 polyricinoleate is preferred because it has an appropriate balance between hydrophilicity and lipophilicity.

[0051] The surfactant may be any commercially available product without any particular limitations. It is preferable to use a premix product in which the surfactant (f) and the organically modified clay mineral (b) are mixed in advance, as this makes it easier to prepare the formulation.

[0052] When the water-in-oil emulsion composition of the present embodiment contains a surfactant, the content of the surfactant is preferably 1 to 20% by mass relative to the total mass (100% by mass) of the water-in-oil emulsion composition. When the content of the surfactant is within the above-mentioned preferred range, it becomes possible to efficiently increase the viscosity of the water-in-oil emulsion composition by combining with the organically modified clay mineral, which is component (b). The content of the surfactant in the water-in-oil emulsion composition of the present embodiment is more preferably 2 to 15% by mass, and even more preferably 3 to 10% by mass.

[0053] (Emulsifier: component (g)) The water-in-oil emulsion composition of the present embodiment preferably contains an emulsification aid (hereinafter, sometimes referred to as "component (g)"). When the water-in-oil emulsion composition contains an emulsification aid, the stability of the water-in-oil emulsion composition can be further increased.

[0054] Specific examples of the emulsifying aid include sodium chloride, magnesium sulfate, etc. Among these, it is preferable to use magnesium sulfate as the emulsifying aid because it provides a more excellent feeling when used.

[0055] When the water-in-oil emulsion composition of the present embodiment contains an emulsification aid, the content of the emulsification aid is preferably 0.1 to 5 mass% relative to the total mass (100 mass%) of the water-in-oil emulsion composition. When the content of the emulsification aid is within the above-mentioned preferred range, the content of the surfactant, which is the component (f), can be reduced, making it possible to emulsify more efficiently. The content of the emulsification aid in the water-in-oil emulsion composition of the present embodiment is more preferably 0.5 to 3 mass%.

[0056] (Preservatives: ingredient (h)) The water-in-oil emulsion composition of the present embodiment preferably contains a preservative (hereinafter, may be referred to as "component (h)"). When the water-in-oil emulsion composition contains a preservative, it is possible to prevent deterioration of the components in the composition.

[0057] Specific examples of the preservative include phenoxyethanol, methylparaben, propylparaben, hydroxyacetophenone, etc. Among these, parabens such as methylparaben and propylparaben are preferred because they exhibit high antibacterial activity even in small amounts and exhibit antibacterial activity evenly against various types of bacteria.

[0058] When the water-in-oil emulsion composition of the present embodiment contains a preservative, the content of the preservative may be, for example, 0.1 to 0.6% by mass relative to the total mass (100% by mass) of the water-in-oil emulsion composition, depending on the type of preservative. When the preservative is phenoxyethanol, the content is preferably 0.1 to 0.6% by mass, and more preferably 0.2 to 0.5% by mass. When the preservative is methylparaben and / or propylparaben, the content is preferably 0.1 to 0.5% by mass, and more preferably 0.2 to 0.4% by mass. When the content of the preservative is within the above-mentioned preferred range, sufficient antibacterial activity can be exhibited and irritation to the skin can be suppressed.

[0059] (Others: (i) Ingredients) In addition to the above-mentioned components, the water-in-oil emulsion composition of the present embodiment may contain any component commonly used in cosmetics (hereinafter, sometimes referred to as “component (i)”) within a range that does not impair the effects of the present invention. Examples of such ingredients include antioxidants (e.g., tocopherol), moisturizers (e.g., glycerin), antibacterial agents, whitening agents, vitamins and their derivatives, anti-inflammatory agents, anti-inflammatory agents, blood circulation promoters, hormones, anti-wrinkle agents, anti-aging agents, tightening agents, cooling agents, warming agents, wound healing promoters, irritation mitigators, analgesics, cell activators, plant, animal, and microbial extracts, antipruritic agents, keratin peeling and dissolving agents, astringents, enzymes, nucleic acids, fragrances, dyes, colorants, anti-inflammatory and analgesic agents, antifungal agents, antihistamines, antibiotics, antibacterial substances, herbal medicines, antipruritic agents, keratin softening and peeling agents, antiseptics, and additives. Specific examples of these ingredients include those described in JP 2016-50196 A. Other ingredients may be used alone or in combination of two or more.

[0060] [Manufacturing method] The water-in-oil emulsion composition of this embodiment can be produced by mixing the above components (a) to (d) and optionally adding other components and mixing them. Specific examples of the production method of the water-in-oil emulsion composition of this embodiment are shown below, but are not limited thereto.

[0061] Component (a) is gradually added to water and dissolved to prepare an aqueous solution of component (a). When component (e) is added, component (e) is dissolved in water beforehand to prepare an aqueous solution of component (e). Other water-soluble components and the aqueous solution of component (e) prepared beforehand are added to the aqueous solution of component (a) at room temperature and dissolved to obtain an aqueous phase. Next, component (b) (preferably a premix with component (f)) is added at room temperature to a mixture of component (c) and other oily components that have been stirred until homogeneous. The mixture is stirred until homogeneous to obtain an oil phase. The oil phase prepared by the above procedure is stirred at room temperature with a stirrer such as a homodisper, while the aqueous phase is gradually added to the oil phase over about 10 minutes. After that, the mixture is further stirred for about 5 minutes with a dispersing machine such as a Polytron (registered trademark) homogenizer, to obtain a water-in-oil emulsion composition.

[0062] The shape of the stirring blade of the homodisper is not particularly limited, and for example, a paddle type, an anchor type, a propeller type, etc. can be used. The rotation speed of the homodisper is, for example, 600 to 2000 rpm, preferably 800 to 1600 rpm. The shape and size of the generator shaft of the Polytron homogenizer are not particularly limited, and a commercially available product can be appropriately used. The rotation speed of the Polytron homogenizer is, for example, 1000 to 7000 rpm, and preferably 2000 to 6000 rpm.

[0063] The viscosity of the prepared water-in-oil emulsion composition at 25°C is preferably 9 to 50 Pa·s, and more preferably 12 to 45 Pa·s. When the viscosity is within the above-mentioned preferred range, a more stable emulsified state can be maintained. When the water-in-oil emulsion composition has a viscosity of 14 to 40 Pa·s at 25°C, yellowing of the water-in-oil emulsion composition can be suppressed, which is more preferable. The viscosity of the water-in-oil emulsion composition was measured using a B-type viscometer under the conditions described in the Examples below.

[0064] The water-in-oil emulsion composition of this embodiment contains the above components (a) to (d) and also contains the component (b) at a specific content (0.2 to 4.5% by mass), so that even when it contains a high concentration (for example, 3% by mass or more, 6% by mass or more, or 8% by mass or more) of ascorbic acid phosphate and / or its salt, it has excellent emulsion stability and is less likely to precipitate ascorbic acid phosphate and / or its salt. In addition, since any oily agent other than silicone oil can be blended as an oily agent, it is possible to adjust the desired feel of use according to the application of the formulation such as a cosmetic. In addition, by further containing a thickener as the component (e), stability is further improved and yellowing can be suppressed. EXAMPLES

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

[0066] In the following examples and comparative examples, ascorbic acid PM (hereinafter referred to as "magnesium ascorbyl phosphate") manufactured by Showa Denko KK was used as component (a). In Comparative Example 2, bentonite (Kunipia-G10, manufactured by Kunimine Industries Co., Ltd.), which is a clay mineral (hereinafter referred to as component (b')), was used in place of the organically modified clay mineral, which is component (b).

[0067] The product names of other components used in the following Examples and Comparative Examples are shown below. (e) Xanthan gum: KELTROL CG-SFT (CP Kelco) (e) Gellan gum: KELCOGEL CG-LA (manufactured by CP Kelco) (e) Hydroxyethyl cellulose: HEC Daicel SE550 (manufactured by Daicel FineChem Co., Ltd.) (b) Disteardimonium hectorite (premixed with (f) polyglyceryl-6 polyricinoleate and (f) polyglyceryl-2 isostearate): NIKKOL Nikomulus WO-NS (manufactured by Nikko Chemicals Co., Ltd.) (b) Quaternium-18 hectorite: Sumecton-SAN-P (manufactured by Kunimine Kogyo Co., Ltd.) (c) Caprylyl laurate: NIKKOL GS-KL (manufactured by Nikko Chemicals Co., Ltd.) (c) Isodecyl neopentanoate: Neolite 100P (manufactured by Kokyu Alcohol Kogyo Co., Ltd.) (c) Kukui nut oil: NIKKOL Kukui nut oil (manufactured by Nikko Chemicals Co., Ltd.) (c) Squalane: Squalane (manufactured by Kishimoto Special Liver Oil Industry Co., Ltd.)

[0068] [Example 1] 66.6 g of water was placed in a 100 mL beaker, and 10 g of magnesium ascorbyl phosphate was gradually added and dissolved while stirring with a magnetic stirrer. 1.0 g of glycerin, 1.0 g of magnesium sulfate, and 0.3 g of phenoxyethanol were then added in that order and dissolved until the solution became homogeneous, obtaining aqueous phase A. Next, 6.0 g of caprylyl laurate, 3.0 g of isodecyl neopentanoate, 4.0 g of squalane, 1.0 g of kukui nut oil, 1.0 g of dimethicone, and 0.1 g of tocopherol were added to a 200 mL beaker and stirred gently with a magnetic stirrer to make the mixture uniform. 6.0 g of NIKKOL Nikomulus WO-NS (manufactured by Nikko Chemicals Co., Ltd.) was then added and stirred until the paste-like portion was uniformly dispersed to obtain oil phase B. While stirring the oil phase B at room temperature at 1000 rpm using a Three-One Motor (registered trademark) FBL1200 (manufactured by Shinto Scientific Co., Ltd.) (stirring blade: SUS Disper 80 mm with boss DP80), the aqueous phase A was gradually added to the oil phase B over 10 minutes. The mixture was then thoroughly stirred at 3000 rpm for 5 minutes using a T 25 digital ULTRA-TURRAX (manufactured by IKA Japan Co., Ltd.) (shaft model number: S25N-18G) to obtain a water-in-oil emulsion composition.

[0069] [Examples 2 and 3] A water-in-oil emulsion composition was prepared using the ingredients and amounts shown in Table 1 in the same manner as in Example 1.

[0070] [Example 4] 0.1 g of xanthan gum was dissolved uniformly in 4.9 g of water to prepare a 2% xanthan gum aqueous solution. 61.6 g of water was placed in a 100 mL beaker, and 10 g of magnesium ascorbyl phosphate was gradually added while stirring with a magnetic stirrer to dissolve the water. 1.0 g of glycerin, 1.0 g of magnesium sulfate, 0.3 g of phenoxyethanol, and 5.0 g of the above xanthan gum aqueous solution were added in that order and dissolved until the solution became uniform, obtaining aqueous phase A. Next, 6.0 g of caprylyl laurate, 3.0 g of isodecyl neopentanoate, 4.0 g of squalane, 1.0 g of kukui nut oil, 1.0 g of dimethicone, and 0.1 g of tocopherol were added to a 200 mL beaker and stirred gently with a magnetic stirrer to make the mixture uniform. 6.0 g of NIKKOL Nikomulus WO-NS (manufactured by Nikko Chemicals Co., Ltd.) was then added and stirred until the paste-like portion was uniformly dispersed to obtain oil phase B. While stirring oil phase B at room temperature at 1000 rpm using a homodisper, aqueous phase A was gradually added to oil phase B over 10 minutes. The mixture was then thoroughly stirred at 3000 rpm for 5 minutes using a Polytron homogenizer to obtain a water-in-oil emulsion composition.

[0071] [Examples 5 to 22, Comparative Examples 1 and 2] Water-in-oil emulsion compositions were prepared using the ingredients and amounts shown in Tables 1 and 2, respectively, in the same manner as in Example 4. Of the formulations shown in Tables 1 and 2, the formulation of Comparative Example 2 did not allow the preparation of a water-in-oil emulsion composition.

[0072] [Examples 23 to 25] Water-in-oil emulsion compositions were prepared using the components and amounts shown in Table 3 in the same manner as in Example 4. In Examples 23 to 25, a preservative (component (h)) was also added to the oil phase B.

[0073] The premixed product NIKKOL Nikomulus WO-NS (manufactured by Nikko Chemicals Co., Ltd.) contains 10 to 20% by mass of disteardimonium hectorite. Therefore, for example, when 0.5% by mass of the premixed product is added (Comparative Example 1), the content of disteardimonium hectorite in the water-in-oil emulsion composition is 0.05 to 0.1% by mass, and when 4.0% by mass of the premixed product is added (Example 20), the content of disteardimonium hectorite in the water-in-oil emulsion composition is 0.4 to 0.8% by mass. That is, the content of component (b) is 0.2 mass % or more in Examples 1 to 25, and less than 0.2 mass % in Comparative Example 1.

[0074] [Table 1]

[0075] [Table 2]

[0076] [Table 3]

[0077] [Viscosity measurement] The viscosity of the prepared water-in-oil emulsion composition at 25° C. was measured using a Brookfield viscometer LVDV2T (manufactured by Eiko Seiki Co., Ltd.) with a RV-2 spindle as the spindle size. The measurement results at 12 rpm are shown in Tables 1 to 3.

[0078] [Stability evaluation test 1] The prepared water-in-oil emulsion compositions (hereinafter referred to as "samples") were evaluated for stability over time based on the presence or absence of crystal precipitation. Plastic wrap was prepared and placed horizontally on a desk, and both the left and right sides were fixed to the desk with packing tape. A square area of ​​1.5 cm length and width was set on top of it in a row, the number of samples being equal. 0.2 g of the sample was evenly applied to each area. An iron bar wrapped with plastic wrap was prepared and used to stretch the sample evenly vertically to 15 cm. After that, a hair dryer was used to blow air (approximately 25°C) evenly over the sample for 30 seconds. A 30-second blowing process was counted as one set, and the condition of the sample was checked after each set for all samples. This operation was repeated 10 times. The results are shown in Tables 1 to 3. The presence or absence of crystal precipitation in the sample was evaluated according to the following criteria. "Whether or not crystals are precipitated" A: No crystal precipitation was observed even after 10 sets. B: Crystal precipitation was observed by the end of the fourth set.

[0079] In Comparative Example 1, crystal precipitation was observed in the system after the completion of the fourth set, and it was confirmed that the number of crystals increased with continued air blowing. It is considered that, since the content of the organically modified clay mineral in Comparative Example 1 was low, the oil phase could not be sufficiently gelled, and the aqueous phase was united, resulting in the precipitation of magnesium ascorbyl phosphate crystals. On the other hand, no crystal precipitation was observed even after 10 sets in Examples 1 to 25. Thus, it was confirmed that Examples 1 to 25 were water-in-oil emulsion compositions in which crystal precipitation over time was suppressed and which had excellent emulsion stability.

[0080] [Stability evaluation test 2] The prepared water-in-oil emulsion compositions (hereinafter referred to as "samples") were subjected to an accelerated test at 50°C, and the stability over time was evaluated based on separation and yellowing of the samples. 30mL vials were prepared for the number of samples, and each sample was filled to a height of 4cm from the bottom. After filling, the vials were closed and stored at 50℃ in an air atmosphere. After one month, each sample was observed for separation and yellowing. The results are shown in Tables 1 to 3. The presence or absence of separation and yellowing of the sample was evaluated according to the following criteria. "Whether or not there is separation" A: No phase separation was observed. B: Phase separation was observed. "Whether or not yellowing occurs" A: No yellowing was observed and the color remained milky white. B: Yellowing was observed.

[0081] For Examples 1, 8, 9, 12, 13, 17, 20, and Comparative Example 1, in which yellowing was observed as described above, small samples were taken from the bottom (0 to less than 1.3 cm from the bottom), middle (1.3 to less than 2.6 cm from the bottom), and top (2.6 to 4.0 cm from the bottom) of each sample vial, and the color change of the samples was evaluated using the Munsell color system using a color scheme sample (Japan Paint Manufacturers Association Color Sample Book Paint Standard Colors 2019 K Edition Pocket Edition). The results are shown in Table 4.

[0082] [Table 4]

[0083] In Comparative Example 1, phase separation of the sample was confirmed, and the separated lower phase (lower and middle parts of the vial) turned dark yellow (hue 2.5Y to 7.5Y, value 9.0, chroma 10.0 to 12.0 in the Munsell color system). Also, slight yellowing (hue 2.5Y to 7.5Y, value 9.0, chroma 6.0 to 10.0 in the Munsell color system) was confirmed in the upper phase (upper part of the vial). In Examples 1, 8, 12, and 13, no phase separation was observed in the samples, but a yellow coloration (hue 2.5Y to 7.5Y, value 9.0, chroma 6.0 to 8.0 in the Munsell color system) was observed in the lower part, and slight yellowing (hue 2.5Y to 7.5Y, value 9.0, chroma 4.0 to 6.0 in the Munsell color system) was observed in the middle and upper parts. In Examples 9 and 17, no phase separation was observed in the samples, but slight yellowing (hue 2.5Y to 7.5Y, value 9.0, chroma 2.0 to 4.0 in the Munsell color system) was observed in the lower, middle, and upper parts. In Example 20, no phase separation of the sample was observed, but a deep yellow coloration (hue 2.5Y to 7.5Y, value 9.0, chroma 8.0 to 10.0 in the Munsell color system) was observed in the lower part, and a yellow coloration (hue 2.5Y to 7.5Y, value 9.0, chroma 6.0 to 8.0 in the Munsell color system) was also observed in the middle part. In addition, a slight yellowing (hue 2.5Y to 7.5Y, value 9.0, chroma 4.0 to 6.0 in the Munsell color system) was observed in the upper part. On the other hand, in Examples 2 to 7, 10, 11, 14 to 16, 18, 19, and 21 to 25, no phase separation or yellowing was observed in the samples, and the milky white color was maintained.

[0084] As the emulsion of the water-in-oil emulsion composition breaks down, the aqueous phase is thought to aggregate, cream, coalesce, and accumulate at the bottom of the sample. The aqueous phase in which magnesium ascorbyl phosphate is dissolved is yellow when stored at high temperatures for a long period of time. Therefore, it is presumed that as the emulsion breaks down, the bottom of the sample becomes a deeper yellow color. On the other hand, no separation of the samples was observed in Examples 1 to 25, which had a viscosity of 9 Pa s or more, and no yellowing of the samples was observed in Examples 2 to 7, 10, 11, 14 to 16, 18, 19, and 21 to 25, which had a viscosity of 14 Pa s or more. From this, it is considered that the progress of separation and yellowing depends on the viscosity of the sample.

[0085] From the results of Stability Evaluation Tests 1 and 2, it was confirmed that the water-in-oil emulsion compositions of Examples 1 to 25 suppressed crystal precipitation over time, and the water-in-oil emulsion compositions of Examples 2 to 7, 10, 11, 14 to 16, 18, 19, and 21 to 25 further suppressed yellowing and had excellent emulsion stability. In particular, it was shown that even water-in-oil emulsion compositions containing magnesium ascorbyl phosphate at a high concentration of 3 mass% or more could suppress crystal precipitation over time.

[0086] From the above results, the present invention can provide a water-in-oil emulsion composition having excellent emulsion stability even when it contains a high concentration of ascorbic acid phosphate and / or a salt thereof. [Industrial Applicability]

[0087] The present invention provides a water-in-oil emulsion composition which contains ascorbic acid phosphate and / or a salt thereof as an active ingredient and is capable of suppressing crystal precipitation over time.

Claims

1. (a) at least one ascorbic acid phosphate compound selected from the group consisting of ascorbic acid phosphate esters and salts thereof; (b) organically modified clay minerals; (c) an oily agent, (d) water; and (e) at least one thickener selected from the group consisting of natural polymers and cellulosic polymers, The content of the (b) component is 0.5 to 1.5 mass %, The content of the component (a) is 3% by mass or more and 12% by mass or less, The component (e) is xanthan gum, gellan gum or hydroxyethyl cellulose, The component (a) is a magnesium salt of ascorbic acid phosphate, The component (b) is an organically modified hectorite, and the organically modified hectorite is disteardimonium hectorite or quaternium-18 hectorite; The content of the component (e) is 0.05 to 0.5 mass %.

2. The water-in-oil emulsion composition according to claim 1, wherein the content of the component (d) is 50 to 90 mass %.

3. 3. The water-in-oil emulsion composition according to claim 1, wherein the mass ratio of the component (c) to the component (d) is (c):(d)=1:2 to 1:

10.

4. The water-in-oil emulsion composition according to any one of claims 1 to 3, having a viscosity measured at 25°C of 9 to 50 Pa·s.

5. The water-in-oil emulsion composition according to any one of claims 1 to 4, which is a cosmetic.

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