Oil-in-water type emulsified composition

Abstract

To provide a composition containing nanodisks consisting of silicone-based surfactant in which stability of an emulsified composition is improved.SOLUTION: An oil-in-water type emulsified composition contains (A) a water phase, (B) an oil phase and (C) polyoxyalkylene-modified silicone, where (A) the water phase contains ethyl alcohol and dipropylene glycol by 1 to 35 mass% in total, (B) the oil phase by 1 to 50 mass%, (C) by 0.2 to 5 mass% for the whole composition, by which nanodisks are formed, and an emulsion state is stable.SELECTED DRAWING: None

Description

Related Application

[0001] This invention is based on the priority of Japanese Patent Application: Japanese Patent Application No. 2020-036519 (filed on March 4, 2020), and the entire contents of the application are incorporated herein by reference.

Technical Field

[0002] The present invention relates to a nanodisk emulsion composition, a method for producing the same, and in particular, to emulsification in a nanodisk emulsion composition composed of a silicone-based surfactant, and relates to an improvement in emulsion stability and usability.

Background Art

[0003] Among amphiphilic compounds having both hydrophilic and hydrophobic properties, for example, there are those that form spherical vesicles composed of a bilayer membrane (lamellar phase) in an aqueous phase, such as phospholipids. Such bilayer vesicles are called liposomes or vesicles, and they can stably hold an aqueous component inside the vesicles or an oily component inside the vesicle membrane. Therefore, for example, when a drug is held and administered in vivo, it has advantages such as suppressed metabolism and the ability to maintain the drug efficacy over a long period of time, and is thus used as microcapsules in the fields of medicine, cosmetics, food, etc. On the other hand, a nanodisk that does not contain an internal phase is a plate-like dispersion of a lamellar liquid crystal phase. It can stably hold an oily component inside the vesicle membrane but does not contain an internal phase.

[0004] In Patent Documents 1 and 2, it is disclosed that vesicles are formed by using a specific polyoxyethylene hydrogenated castor oil derivative as an amphiphilic substance, and by including this as an emulsifier, a non-greasy cosmetic with good usability was obtained. In addition, silicone-based surfactants have been reported as amphiphilic compounds capable of forming such vesicles (see, for example, Patent Documents 3 to 7). Characteristics of vesicles formed by silicone-based surfactants include, for example, the ability to easily prepare vesicles compared to the case of using surfactants having other vesicle-forming performance. In Patent Document 7, a technique is disclosed in which a liquid phase that is immiscible with water is dispersed in an outer phase by a vesicle containing an inner phase. However, since emulsification by vesicles is unstable and has limitations in practical use, the amount of vesicles tends to increase, and stickiness due to vesicle-forming surfactants, as is generally known, may become a problem. Furthermore, there has been no report of forming nanodisks with silicone-based surfactants.

[0005] [Patent Document 1] WO2010-064678 [Patent Document 2] Japanese Patent Application Laid-Open No. 2011-195509 [Patent Document 3] Japanese Patent Application Laid-Open No. 07-323222 [Patent Document 4] Japanese Patent Application Laid-Open No. 08-239475 [Patent Document 5] Japanese Patent Application Laid-Open No. 09-175930 [Patent Document 6] Japanese Patent No. 5121179 [Patent Document 7] Patent Publication No. 3137592

[0006] [Non-Patent Document 1] H. SAGITANI, Y. HIRAI, K. NABETA and M. NAGAI, Effect of Types of Polyols on Surfactant Phase Emulsification, J. Jpn Oil Chem. Soc., Vol. 35, 102-107 (1986) [Non-Patent Document 2] Kei Watanabe, Miharu Nishida, Kanako Nishimura, Yoriko Mune, Yuji Matsushita, Ayano Nakamura, Koji Tsuchiya, Hideki Sakai, Heinz Hoffmann, High Skin Hydration and Comfortable Texture of a Moisturizing Lotion Fulfilled by Controlling the Phase Sequence of a Vesicle / Micelle Complex, J. Soc. Cosmet. Chem. Jpn., 52, (4) 260-268 (2018)

Summary of the Invention

Problems to be Solved by the Invention

[0007] Regarding conventional vesicle emulsions, their stability over time or with respect to temperature could not be said to be sufficient. The present invention has been made in view of the problems of the prior art, and its object is to improve the stability of an emulsified composition by means of nanodisks rather than by vesicles containing an inner phase.

Means for Solving the Problems

[0008] As a result of intensive studies by the present inventors to solve the problems of the prior art, it has been found that silicone nanodisks that do not contain an inner phase formed by optimizing vesicles that become nanodisk precursors in an oil-in-water emulsified composition containing an aqueous phase, an oil phase, and a specific silicone-based surfactant can maintain emulsification stability by adsorbing to the oil-water interface, leading to the completion of the present invention.

[0009] The oil-in-water emulsified composition according to the present invention is an oil-in-water emulsified composition containing (A) an aqueous phase, (B) an oil phase, and (C) a polyoxyalkylene-modified silicone, (A) The aqueous phase contains a total of 1 to 35% by mass of a monohydric alcohol and a dihydric glycol, with the monohydric alcohol alone in the range of 1 to 15% by mass and the dihydric glycol alone in the range of 1 to 20% by mass. (B) 1 to 50% by mass of an oil phase, (C) 0.2 to 5% by mass based on the whole composition, and is characterized by containing each of them. As the monohydric alcohol in the aqueous phase (A), ethyl alcohol is preferred, and as the dihydric glycol, dipropylene glycol is preferred. Also, the proportion of silicone oil in the oil phase (B) is 50% by mass or less, and the component (C) is PEG-12 dimethicone. Further, PEG-12 dimethicone does not dissolve in water and precipitates at a concentration of 5 to 20% by mass, and is less than 10 in the HLB calculation by the Griffin formula. When the emulsion composition is centrifuged at 40,000 revolutions per minute for 60 minutes, particles with an average particle diameter of 30 nm to 150 nm are present in the transparent layer separated in the lower layer, and when the emulsion composition is centrifuged at 3,000 revolutions per minute for 16 hours, a transparent separation layer of oil with a proportion of 2% in the total volume is not observed in the upper or lower layer. In the oil-in-water type emulsion composition, lamellar nanodisks are adsorbed at the oil-water interface. The major axis of this nanodisk is in the range of 20 nm to 1000 nm. The oil-in-water type emulsion composition can be blended with one or more ionic surfactants selected from sulfosuccinic acid diester salts, alkylallyl sulfonate salts, alkyl ether sulfonate salts, sulfosuccinic acid ester salts, acylmethyl taurine salts, acyl taurine salts, etc. as the component (D), and N-stearoyl-N-methyl taurine salt is particularly preferred. The content of the ionic surfactant (D) can be blended in an amount of 0.01 to 1.0% by mass based on the whole oil-in-water type emulsion composition. In addition, the oil-in-water type emulsion composition can contain a polymer thickener as the component (E) at a concentration of 0.05 to 1% by mass. As the component (E), a carboxyvinyl polymer or its derivative or an acrylic thickener is preferable. When the polymer thickener as the component (E) is an acrylic thickener, it is characterized by being one or more acrylic thickeners selected from (dimethylacrylamide / acryloyldimethyltaurine Na) cross-polymer, acryloyldimethyltaurine ammonium / VP copolymer, (acryloyldimethyltaurine ammonium methacrylic acid behenes-25) cross-polymer, and (sodium acrylate / sodium acryloyldimethyltaurine) copolymer. Furthermore, an elastomer (F) can also be blended in the oil-in-water type emulsion composition.

Effects of the Invention

[0010] The nanodisk-containing composition according to the present invention has improved emulsion stability and good usability by blending specific amounts of an aqueous phase (A), an oil phase (B), and a polyoxyalkylene-modified silicone (C).

Brief Description of the Drawings

[0011]

Figure 1

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Figure 7

Figure 8

Figure 9

Mode for Carrying Out the Invention

[0012] The nanodisc-containing composition according to the present invention contains (A) an aqueous phase, (B) an oil phase, and (C) a polyoxyalkylene-modified silicone. Hereinafter, each component will be described in detail.

[0013] The nanodiscs according to the present invention are vesicles, which are precursors of nanodiscs, in a composition that does not contain oil. This vesicle is not a spontaneous vesicle. A spontaneous vesicle refers to a state of equilibrium of a solution, that is, a solution stored at a constant temperature and constant pressure for an extremely long period is in a vesicle-dispersed state. The vesicle of the present invention is a two-phase coexisting solution of a flat lamellar liquid crystal and water in the equilibrium state of the solution. When this state is dispersed by applying a strong stirring force, it becomes a vesicle. By adding oil and performing emulsification in the state of the vesicle, the structure of the vesicle changes to a nanodisc. Furthermore, when an ionic surfactant is added as a dispersant, it becomes possible to maintain this state over a long period. Thus, the present invention is completed.

[0014] The water-in-oil type emulsion composition by adsorption of the nanodisk of the present invention is characterized by containing a monohydric alcohol or a dihydric glycol. The monohydric alcohol is ethyl alcohol, normal propyl alcohol, isopropyl alcohol, etc. The dihydric glycol is 1,3-butylene glycol, dipropylene glycol, etc. These change the surfactant containing polyether-modified silicone to hydrophilic due to the solvent effect (Non-Patent Document 1). As a result, it promotes the transition from vesicles, which are spherical vesicles, to nanodisks. In vesicles, which are spherical vesicles, the surface is entirely covered with hydrophilic groups, but in nanodisks, the edge part is a lipophilic group, so it is difficult to generate in water. Monohydric alcohols and dihydric glycols are easily transferred to nanodisks because they hydrophilize the surfactant due to the solvent effect. On the other hand, when PEG-12 dimethicone is dissolved in alcohol, trivalent glycerin, tetravalent sorbitol, etc. are not desirable because they lipophilize the surfactant and inhibit the transition to nanodisks, and the blending amount is preferably (total amount of monohydric alcohol and dihydric glycol) > (total amount of trivalent glycerin and tetravalent sorbitol). (A) aqueous phase In the aqueous phase, the total blending amount of the monohydric alcohol and the dihydric glycol may be 1 to 45% by mass, preferably 1 to 35% by mass in the aqueous phase. However, the monohydric alcohol alone is preferably in the range of 1 to 15% by mass, and the dihydric glycol alone is preferably in the range of 1 to 20% by mass. Ethyl alcohol is preferred as the monohydric alcohol. Dipropylene glycol is preferred as the dihydric glycol. More preferably, it is preferable to blend with the upper limit of the ethyl alcohol and dipropylene glycol concentrations satisfying the following [Formula 1]. [Formula 1] Ethyl alcohol concentration in the aqueous phase (% by mass) / 15 + dipropylene glycol concentration in the aqueous phase (% by mass) / 20 ≤ 1

[0015] If the blending amount of ethyl alcohol alone, the blending amount of dipropylene glycol alone, or the total blending amount of ethyl alcohol and dipropylene glycol is less than 1% by mass, vesicles may not be formed or the structure may be disrupted, resulting in the inability to emulsify. If the blending amount of ethyl alcohol alone exceeds 15% by mass, the blending amount of dipropylene glycol alone exceeds 20% by mass, the blending ratio of ethyl alcohol and dipropylene glycol is outside the range of the above [Formula 1], or even if it is within the range of the above [Formula 1] but the total amount exceeds 35% by mass, the vesicle membrane may become too flexible or the vesicles may transfer to micelles, resulting in the inability to obtain a stabilization effect.

[0016] (B) Oil phase The oils that can be formulated in the oil phase are not particularly limited, and examples include silicone oils (e.g., dimethylpolysiloxane, diphenylpolysiloxane, octamethylcyclotetrasiloxane, decamethylcyclopentasiloxane, decamethylcyclohexasiloxane, amino-modified polysiloxane, polyether-modified polysiloxane, alkyl-modified polysiloxane, fluorine-modified polysiloxane, etc.); hydrocarbon oils (e.g., liquid paraffin, ozokerite, squalane, petrolatum, microcrystalline wax, etc.); ester oils (e.g., isopropyl myristate, cetyl octanoate, octyldodecyl myristate, isopropyl palmitate, butyl stearate, hexyl laurate, myristyl myristate, decyl oleate, hexyldecyl dimethyloctanoate, cetyl lactate, myristyl lactate, lanolin acetate, isocetyl stearate, isocetyl isostearate, cholesteryl 12-hydroxystearate, ethylene glycol di-2-ethylhexanoate, dipentaerythritol fatty acid ester, N-alkyl glycol monoisostearate, neopentyl glycol dicaprate, diisostearyl malate, glycerin di-2-heptylundecanoate, trimethylolpropane tri-2-ethylhexanoate, trimethylolpropane triisostearate, glycerin trioctanoate, glycerin triisopalmitate, trimethylolpropane triisostearate, cetyl 2-ethylhexanoate, 2-ethylhexyl palmitate, glycerin trimyristate, glyceride di-2-heptylundecanoate, methyl ester of castor oil fatty acid, oleyl oleate, acetoglyceride, 2-heptylundecyl palmitate, di-2-heptylundecyl adipate, diisobutyl adipate, 2-octyldodecyl N-lauroyl-L-glutamate, ethyl laurate, di-2-ethylhexyl sebacate, 2-hexyldecyl myristate, 2-hexyldecyl palmitate, 2-hexyldecyl adipate, diisopropyl sebacate, 2-ethylhexyl succinate, triethyl citrate, etc.).

[0017] The oil phase is preferably 1 to 50% by mass based on the whole emulsion. In addition, the content of silicone oil in the oil phase is preferably 50% by mass or less. If it exceeds 50% by mass, emulsion particles may coalesce at high temperatures.

[0018] (C) Polyoxyalkylene-modified silicone is a water-soluble silicone surfactant in which a part of the methyl groups of dimethicone is substituted with polyethylene glycol. It is excellent in emulsifying action, dispersing action, and permeating action, and is widely used in the field of cosmetics. It is represented by the following general formula (1).

[0019] [Chemical formula] (In the formula, R 1 is hydrogen or an alkyl group having 1 to 6 carbon atoms. A is such that at least one of them is of the formula: -(CH2) a -(C2H4O) b -(C3H6O) c -R 2 (In the formula, R 2 is hydrogen or an alkyl group having 1 to 6 carbon atoms, a is an integer of 1 to 6, b is an integer of 0 to 50, c is an integer of 0 to 50, b + c is at least 5 or more, and it is a polyoxyalkylene group. The other A is hydrogen or an alkyl group having 1 to 6 carbon atoms. m is an integer of 1 to 200, and n is an integer of 0 to 50.)

[0020] Among the polyoxyalkylene-modified silicones of (C), PEG-12 dimethicone in which c is 0 and b is 12 in [Chemical formula 1] is particularly preferred.

[0021] Examples of commercially available PEG-12 dimethicone include DOWSIL ES-5373 (manufactured by Dow Corning Toray Co., Ltd.), SH3772M, SH3773M, SH3775M (all manufactured by Dow Corning Toray Co., Ltd.), IM-22 (manufactured by Wacker Chemical Co., Ltd.), etc.

[0022] The blending amount of component (C) needs to be an amount that can form vesicles which are precursors of the nanodisks, and it is 0.2 to 5.0% by mass with respect to the whole composition, and more preferably 0.5 to 2.5% by mass. If the blending amount is less than 0.2% by mass, the effect by the nanodisks may not be obtained, and if it exceeds 5.0% by mass, the stability of the nanodisks may be inferior.

[0023] The oil-in-water type emulsion composition according to the present invention contains nanodisks composed of the surfactant of component (C). The formation of vesicles which are precursors of the nanodisks may be carried out by a known method. For example, by mixing the (A) aqueous phase and component (C) and stirring, vesicles composed of component (C) can be formed in the aqueous phase. The average particle diameter of the vesicles is about 30 nm to 150 nm.

[0024] In the oil-in-water type emulsion composition according to the present invention, another (D) ionic surfactant can be further blended. When an ionic surfactant is added, the stability of the nanodisk-containing composition composed of (C) polyoxyalkylene-modified silicone is improved. The ionic surfactant used in the present invention is other than the above-mentioned (C) silicone-based surfactant, and as long as it shows ionic properties, it can be used without particular limitation.

[0025] The blending amount of the (D) ionic surfactant is preferably 0.01 to 1.0% by mass with respect to the whole composition, and more preferably 0.01 to 0.1% by mass. If the blending amount of the surfactant is small, the stabilizing effect of the nanodisks may not be sufficiently obtained. On the other hand, if the blending amount is too large, it may rather have an adverse effect such as solubilizing the vesicles which are precursors of the nanodisks or inhibiting the formation of the nanodisks. Also, the blending amount ratio of (C) polyoxyalkylene-modified silicone and the ionic surfactant is preferably 1:0.01 to 1:0.1.

[0026] In the present invention, as the (D) ionic surfactant that can be blended, an anionic surfactant can be blended. However, when the Kraft point of the anionic surfactant is low (for example, lower than room temperature), the silicone-based surfactant and the anionic surfactant are likely to mix, and the interaction inhibits the transition from vesicles to nanodisks. This is because the anionic surfactant has a high property of forming an aggregate called a spherical micelle. When coexisting with vesicles, it has the effect of maintaining a spherical structure and inhibits the transition to nanodisks.

[0027] In the present invention, as the (D) ionic surfactant that can be blended, among anionic surfactants, sulfonate-type anionic surfactants are preferred. Examples of sulfonate-type anionic surfactants include diester salts of sulfosuccinic acid, alkyl allyl sulfonates, alkyl ether sulfonates, ester salts of sulfosuccinic acid, acylmethyl taurine salts, acyl taurine salts, and the like.

[0028] In the present invention, it is particularly preferable to blend N-acylmethyl taurine salt as the ionic surfactant. Among the N-acylmethyl taurine salts represented by the following general formula (2), N-stearoyl-N-methyl taurine salt is preferable.

[0029]

Chemical formula

[0030] In the present invention, an (E) polymer thickener can be further blended. As the (E) polymer thickener, carboxyvinyl polymer or its derivative, or acrylic acid-based thickener is preferred. Among them, it is preferably one or more selected from carboxyvinyl polymer, (dimethylacrylamide / acryloyldimethyltaurine Na) cross-polymer, (acryloyldimethyltaurine ammonium / VP) copolymer, (acryloyldimethyltaurine ammonium behenate-25 / methacrylic acid) cross-polymer, and (sodium acrylate / sodium acryloyldimethyltaurine) copolymer.

[0031] (E) The polymer thickener can be formulated according to the required usability of the formulation, but 0.05 to 1.0% by mass is preferred based on the whole water-in-oil type emulsion composition.

[0032] In the present invention, (F) a silicone elastomer can be further formulated. When a silicone elastomer is added to a composition such as a cosmetic, a smooth and refined feeling of use can be given to the user. Examples of the silicone elastomer include silicone elastomers (organopolysiloxanes). The silicone elastomer includes, for example, crosslinked silicones (crosslinked organopolysiloxanes) in which silicone polymers are three-dimensionally crosslinked. When a silicone elastomer is used, stickiness can be suppressed and smoothness (slipperiness) during application to the skin can be obtained.

[0033] The silicone elastomer applicable to the composition of the present application is not particularly limited as long as it is applicable to the skin. Examples of the silicone elastomer include dimethicone crosspolymer, dimethicone / vinyl dimethicone crosspolymer, dimethicone / phenyl vinyl dimethicone crosspolymer, vinyl dimethicone / lauryl dimethicone crosspolymer, lauryl polydimethylsiloxyethyl dimethicone / bis-vinyl dimethicone crosspolymer, alkyl (C30-45) cetearyl dimethicone crosspolymer, cetearyl dimethicone crosspolymer, and the like.

[0034] For silicone elastomers, for example, commercially available products can be used. The commercially available product may be a mixture of a silicone elastomer and an oily component. The oily component contained in this commercially available product is not particularly limited as long as it is applicable to the skin. For example, commercially available products containing silicone elastomers include Gransil DMG-3 (Grant) containing 12% by mass of polysilicone-11 as the silicone elastomer and 88% by mass of dimethicone as the oily component, and other products such as KSG-16 (Shin-Etsu Chemical Co., Ltd.), Dow Corning (registered trademark) 9041 Silicone Elastomer Blend (Toray Dow Corning Co., Ltd.), and the like. The content rate of the silicone elastomer in the composition of the present application is preferably 0.1% by mass or more, and more preferably 0.3% by mass or more with respect to the total amount of the composition.

[0035] Glycerin can also be further blended to impart the "smoothness when applied" required by purchasers as cosmetics. Usually, when glycerin is highly blended, stickiness is felt and good usability cannot be obtained. In the present invention, even when glycerin is highly blended, stickiness is not felt and a smooth feeling can be obtained.

[0036] The method for producing the oil-in-water type emulsion composition according to the present invention includes a vesicle formation step of mixing (A) an aqueous phase and (C) a polyoxyalkylene-modified silicone to form vesicles. Further, a step of adding an ionic surfactant to the aqueous solution containing vesicles obtained by the above step can also be added.

[0037] In the method for producing the oil-in-water type emulsion composition according to the present invention, first, (A) an aqueous phase and (C) a polyoxyalkylene-modified silicone are mixed to form vesicles which are precursors of nanodisks. Here, (A) the aqueous phase is not particularly limited as long as it is a formulation mainly composed of water and an aqueous solvent (monohydric alcohol and / or dihydric glycol). In addition to water or an aqueous solvent, usually, components used in cosmetics may be blended in an amount that does not impair the stability of the nanodisks.

[0038] Pre-dissolve (C) polyoxyalkylene-modified silicone in the monohydric alcohol and / or dihydric glycol which are the components of the above-mentioned (A) aqueous phase, and mix it with water which is the remaining component of the (A) aqueous phase, whereby vesicles which are precursors of nanodisks composed of polyoxyalkylene-modified silicone are formed in the aqueous phase. By adding oil to the aqueous phase containing vesicles which are precursors of the nanodisks and stirring, the vesicles which are precursors of the nanodisks are transferred and adsorbed onto the nanodisks at the oil-water interface, and thus the present invention is completed.

[0039] The oil-in-water type emulsion composition according to the present invention can be suitably used, for example, as a cosmetic. When used as a cosmetic, in addition to the above essential components, it can be formulated in a blending amount within a range that does not impair the stability of components usually used in pharmaceuticals and cosmetics. Further, although the present nanodisk-containing composition can contain an amount of oil that cannot be formulated by ordinary solubilization, stickiness is suppressed and a refreshing feeling of use can be obtained. Note that other formulation components may be formulated in the aqueous phase before vesicle formation in advance, or may be formulated in the formulation after vesicle formation.

[0040] The use of the cosmetic according to the present invention is not particularly limited, but it can be suitably used, for example, as a lotion, a skin care essence, a milky lotion, a cream, a hair cream, a massage cream, a makeup remover cream, etc.

Example

[0041] Hereinafter, the present invention will be described in more detail with reference to examples of the present invention, but the present invention is not limited thereto. In the following, unless otherwise specified, the blending amounts are expressed in mass%.

[0042] [Test Example 1] Preparation of vesicles which are precursors of nanodisks and conditions for vesicle formation After preparing the aqueous phase parts shown in Table 1-1 and Table 1-2 by a conventional method, the inventors mixed them with PEG-12 dimethicone and had them visually evaluated by experts and measured for the average particle size. The average particle size was measured using a zeta sizer (Zeta Sizer Nano ZS manufactured by Malvern Pamalytical).

[0043] [Evaluation method] A: The average particle size at room temperature of 25 °C is 30 nm to 150 nm, and it is judged to have vesicles with a bluish-white appearance B: The average particle size at room temperature of 25 °C is less than 30 nm, and it is judged to be micelles with a colorless and transparent appearance C: The average particle size at room temperature of 25 °C exceeds 150 nm and is less than 250 nm, and it is judged to be turbid with aggregates and in an insoluble state

[0044]

Table 1-1

[0045]

Table 1-2

[0046] As is clear from Table 1-1 and Table 1-2, when the contents of ethyl alcohol and dipropylene glycol are less than 2.5% by mass, PEG-12 dimethicone does not dissolve in the aqueous phase. It can be seen that vesicles are formed when the content of ethyl alcohol is 2.5% by mass to 15% by mass and that of dipropylene glycol is 2.5% by mass to 20% by mass.

[0047] [Test Example 2] Next, the inventors adjusted PEG-12 dimethicone to always be 1.0% by mass in the composition and examined the relationship between the difference due to the HLB of PEG-12 dimethicone and the blending amount of ethyl alcohol. The evaluation method was the same as in Test Example 1. The results are shown in Table 2.

[0048]

Table 2

[0049] When the HLB of PEG-12 dimethicone is 5, vesicles, which are precursors of nanodisks, are formed when the blending amount of ethyl alcohol is 5 to 50% by mass. When the HLB of PEG-12 dimethicone is 8, vesicles, which are precursors of nanodisks, are formed when the concentration of ethyl alcohol is 2.5 to 10% by mass. Further, when the HLB of PEG-12 dimethicone is 13, micelles are formed without forming vesicles, which are precursors of nanodisks, regardless of the content of ethyl alcohol. Furthermore, when the HLB of PEG-12 dimethicone is 7 or less and the content of ethyl alcohol is 5% by mass or less, PEG-12 dimethicone is insoluble in the aqueous phase.

[0050] [Test Example 3] [Examination of the oil content in nanodisk emulsification] Next, the inventors examined the amount of oil when emulsifying using vesicles, which are precursors of nanodisks. The results are shown in Table 3. The aqueous phase contained only water, ethyl alcohol, and PEG-12 dimethicone, and the concentration of ethyl alcohol was set to be always 10% by mass in the aqueous phase. Oil was added to the aqueous phase. The concentration of PEG-12 dimethicone was set to be 1.0% by mass.

[0051] (Method for evaluating the state) The evaluation was performed as follows. A: In terms of appearance, creaming was observed immediately and over time (4 weeks), but no significant coalescence or enlargement of the emulsion particles was observed under optical microscope observation. B: Separation of oil was observed in terms of appearance, and coalescence of emulsion particles was observed under optical microscope observation.

[0052] [Table 3] (*1) DOWSIL ES-5373 (manufactured by Dow Corning Toray Co., Ltd.) (*4) Silicone KF-96A-6T (manufactured by Shin-Etsu Chemical Co., Ltd.) (*5) NOMCOAT HP-30 (manufactured by Nisshin Oillio Group, Ltd.) (*6) RA-PE-408 (manufactured by Nippon Fine Chemical Co., Ltd.)

[0053] From Table 3, it was shown that blending was possible stably up to an oil content of about 50% by mass. Furthermore, although not shown in the table, when the oil content exceeded 60% by mass, the oil slightly floated. It was shown that when using silicone oil alone, blending was possible stably up to about 30% by mass.

[0054] [Test Example 4] Furthermore, the inventors examined the type and blending amount of the oil component. The results are shown in Table 4. The evaluation method is the same as in Test Example 3.

[0055] [Table 4] (*1) DOWSIL ES-5373 (manufactured by Dow Corning Toray Co., Ltd.) (*4) Silicone KF-96A-6T (manufactured by Shin-Etsu Chemical Co., Ltd.) (*5) NOMCOAT HP-30 (manufactured by Nisshin Oillio Group, Ltd.) (*6) RA-PE-408 (manufactured by Nippon Fine Chemical Co., Ltd.)

[0056] From Table 4, it can be seen that when the oil content is 50% by mass or less in the mixing ratio of water and oil, if the mixing ratio of silicone oil in the oil content exceeds 70% by mass, coalescence of emulsion particles is observed in terms of appearance and oil separation occurs. When the mixing ratio of silicone oil in the oil content is 50% by mass or less, although creaming is observed from immediately after emulsification over time (4 weeks) in terms of appearance, coalescence or separation of the oil is not observed, and also under optical microscope observation, no significant coalescence or enlargement of emulsion particles is recognized, indicating that stable blending is possible.

[0057] [Test Example 5] Examination of Emulsifying Power Depending on Oil Type The inventors examined whether there is a difference in emulsifying power depending on the type of oil. The results are shown in Table 5. The evaluation was carried out as follows. A: The change rate of the particle diameter of the oil (particle diameter over time / initial particle diameter) under an optical microscope is 0.8 to 1.2 of the initial value after 4 weeks at a storage temperature of 0°C to 50°C. B: The above change rate exceeds 1.2 or is less than 0.8.

[0058]

Table 5

[0059] From the results of Table 5, the compatibility with PEG-12 dimethicone with an HLB of 10 or less is high, and the oils that are difficult to emulsify are in the order of silicone oil > hydrocarbon oil > polar oil. Therefore, it can be said that the order of high emulsification stability is polar oil > hydrocarbon oil > silicone oil. It was shown that the emulsification stability tends to deteriorate when there are many oils with high compatibility with the surfactant.

[0060] [Test Example 6] The inventors confirmed the emulsified state due to the difference in the content of alcohol (ethyl alcohol) and examined the structure of PEG-12 dimethicone before and after emulsification.

[0061] After preparing the aqueous phase with the formulation shown in Table 6, an oil component was added and treated with a homogenizer (7000 rpm, 3 minutes) to prepare an emulsified composition. The obtained emulsified composition was centrifuged (3000 rpm, 16 h), and the peak value of the particle size of the supernatant was measured with a Zetasizer Nano ZS manufactured by Malvern Pamalytical. The results of the peak value of the aqueous phase before emulsification are shown in Figures 2, 4, and 6, and the results of the peak value after centrifugation treatment after emulsification are shown in Figures 3, 5, and 7.

[0062]

Table 6

[0063] In Test Example 6, from Figures 1 and 2 in Test Example 6-1, when the ethyl alcohol content is 0% by mass, PEG-12 dimethicone is not dissolved in the aqueous phase and is in an insoluble state. No significant change is seen in the peak before and after emulsification. From Figures 4 and 5 in Test Example 6-2, when the alcohol content is 20% by mass, micelles are formed, and no significant change is seen in the peak before and after emulsification. Since many PEG-12 dimethicones are in the state of micelles, it was shown that at the oil-water interface, the micelles are emulsified as a deformed and cracked monomolecular adsorption layer. On the one hand, in Test Example 6-3, as shown in FIGS. 5 and 6, when the ethanol content is 10% by mass, vesicles, which are the precursors of nanodisks, are formed before emulsification. Vesicles are usually smaller than 1 micron, which is the size of emulsified particles, and larger than 10 nm, which is the size of micelles. In this system, particles in the range of about 30 nm to 200 nm are formed, indicating that they are vesicles. In addition, Non-Patent Document 2 discloses the formation of vesicles in this composition. After emulsification, it is considered that emulsification is stabilized by the adsorption of the deformed structure of vesicles, i.e., nanodisks, to the oil-water interface.

[0064] [Test Example 7] Stability and usability in each state The emulsified state was divided into insoluble (the state where PEG-12 dimethicone is not dissolved in the aqueous phase), nanodisks (the state where vesicles, the precursors of nanodisks, are formed), and micelles (the state where PEG-12 dimethicone forms micelles in the aqueous phase), and the stability and usability in each state were examined. Note that for insoluble, nanodisks, and micelles, after preparing the aqueous phase with water, ethyl alcohol, and PEG-12 dimethicone according to the formulations shown in Table 7, an oil component was added and the mixture was treated with a homogenizer (7000 rpm, 3 minutes) to prepare an emulsified composition. The evaluation methods for each item are shown below, and the results are shown in Table 7.

[0065] (Evaluation method for centrifugal stability) The change in the emulsified particle size after centrifugation at 3,000 rpm for 16 hours and 40,000 rpm for 1 hour was observed and evaluated with an optical microscope. A: There was no change in the emulsified particle size B: The emulsified particle size changed, but no change in shape such as separation was observed C: Separation occurred and the formulation became unviable (Evaluation method for penetration feeling) Seven professional panelists applied this test product to their skin, and the effect was evaluated. It was classified as follows according to the number of panelists who answered that "there is a feeling of penetration into the skin". A: 5 or more B: 3 - 4 C: 0 to 2 persons (Evaluation method for elongation during coating) The effects of applying this test product to the skin by 7 professional panelists were evaluated as follows, and classified as follows according to the number of panelists who answered "there is elongation on the skin". A: 5 persons or more B: 3 to 4 persons C: 0 to 2 persons (Evaluation method for stickiness after coating) The effects of applying this test product to the skin by 7 professional panelists were evaluated as follows, and classified as follows according to the number of panelists who answered "there is no stickiness". If there is a more characteristic feeling of use, it will be appended. A: 5 persons or more B: 3 to 4 persons C: 0 to 2 persons

[0066]

Table 7

[0067] From the results of Table 7 in Test Example 7, as shown in Test Example 7-2, in the state where the nanodisk was formed, both the stability and usability were better than those in other states.

[0068] [Test Example 8] By the way, the nanodisk emulsion composition according to the present invention is suitable for blending in cosmetics. The inventors examined the blending amount when PEG-12 dimethicone was added to cosmetics. The results are shown in Table 8. The evaluation methods for appearance and usability were as follows.

[0069] (Evaluation method for state) The evaluation was conducted as follows. A: In terms of appearance, creaming can be observed from immediately after and over time (4 weeks), but no significant coalescence or enlargement of the emulsion particles is observed under optical microscope observation. B: Oil separation is observed in terms of appearance, and coalescence of the emulsion particles is observed under optical microscope observation. (Evaluation method for elongation during application) The effects of applying this test product to the skin by 7 professional panelists were evaluated as follows, and classified as follows according to the number of panelists who answered that "the formulation spreads smoothly without sticking to the fingers during application". A: 5 or more B: 3 - 4 C: 0 - 2 (Evaluation method for stickiness after application) The effects of applying this test product to the skin by 7 professional panelists were evaluated as follows, and classified as follows according to the number of panelists who answered that "it is not sticky". A: 5 or more B: 3 - 4 C: 0 - 2

[0070]

Table 8

[0071] From Table 8, it was shown that when the blending amount of PEG - 12 dimethicone is more than 0.6% by mass, the usability of the cosmetic becomes good. It was also shown that when PEG - 12 dimethicone is more than 0.8% by mass, the usability becomes even better.

[0072] [Test Example 9] The inventors examined the compounding amount when adding an ionic surfactant to a cosmetic. The results are shown in Table 9. In addition, in order to confirm the stability, after storing at 50 °C for one week, the state of the emulsion particles was observed with an optical microscope.

[0073] (Evaluation of changes in emulsion particle size) A: There was no change in the emulsion particle size B: The emulsion particle size changed, but no change in shape such as separation was observed C: Separation occurred and the formulation became unviable

[0074]

Table 9

[0075] From Table 9, it was shown that the stability of the formulation was good when the amount of the ionic surfactant was compounded at 0.01 to 0.1% by mass.

[0076] [Test Example 10] The inventors examined the effect when a polyoxyalkylene-modified silicone and an anionic surfactant were combined. The evaluation of usability and stability was conducted as follows. The emulsion particle size was observed using an optical microscope. The results are shown in Table 10.

[0077] (Evaluation criteria for usability) A: 9 to 10 out of 10 professional panelists evaluated it as non-sticky B: 7 to 8 out of 10 professional panelists evaluated it as non-sticky C: 4 to 6 out of 10 professional panelists evaluated it as non-sticky D: 3 or less out of 10 professional panelists evaluated it as non-sticky (Evaluation criteria for stability) A: The average particle diameter after storage at 50°C for 2 weeks shows no change from the particle diameter immediately after preparation. B: The average particle diameter after storage at 50°C for 2 weeks is less than 1.1 times the particle diameter immediately after preparation. C: The average particle diameter after storage at 50°C for 2 weeks is 1.1 or more and less than 1.5 times the particle diameter immediately after preparation. D: The average particle diameter after storage at 50°C for 2 weeks is 1.5 or more times the particle diameter immediately after preparation.

[0078]

Table 10

[0079] As can be seen from Table 10, in the case of anionic surfactants in the evaluation 2 weeks after sample preparation, a compounding amount or conditions that do not inhibit nanodisk formation are required. In the case of sodium N-stearoyl-N-methyltaurine, good usability and stability were maintained even at 0.6 mass%, while in the case of disodium N-stearoyl-L-glutamate, neither usability nor stability was obtained. It was suggested that sodium N-stearoyl-N-methyltaurine does not affect nanodisk formation. On the other hand, it was suggested that disodium N-stearoyl-L-glutamate inhibits nanodisk formation. It was shown that a compounding amount of 0.01 mass% of sodium N-stearoyl-N-methyltaurine has an excellent stability effect compared to 0.6 mass%.

[0080] [Test Example 11] The inventors examined the compounding amount when adding a thickener to cosmetics. The evaluation methods for appearance and usability are shown below, and the results are shown in Table 11.

[0081] (Evaluation method for state) A: In terms of appearance, no creaming, etc. is observed from immediately after to over time (4 weeks). B: Changes in the situation such as creaming are observed over time (4 weeks). (Evaluation method for refreshing feeling during application) Seven professional panelists applied this test product to their skin, and the effects were evaluated as follows. They were classified as follows according to the number of panelists who answered that they "felt refreshed". A: 5 or more people B: 3 - 4 people C: 0 - 2 people

[0082]

Table 11

[0083] As shown in Table 11, in the test examples where no creaming occurred, a refreshing feeling was obtained regardless of the type of thickener.

[0084] [Test Example 12] The inventors examined the usability when a high amount of glycerin was incorporated into the nanodisc emulsified cosmetic as a moisturizer. The results are shown in Table 12. The stickiness after application was evaluated in the same manner as in Test Example 7. The smoothness is the result of comparison with Test Example 12-1. In the test example, PEG-12 dimethicone dissolved in ethyl alcohol was added to the aqueous phase containing water and glycerin to form vesicles serving as nanovesicle precursors. An oil phase was added to this aqueous phase to prepare an emulsified composition. However, glycerin can also be added later to the aqueous phase containing water and PEG-12 dimethicone dissolved in ethyl alcohol.

[0085]

Table 12

[0086] From Table 12, it was found that the smoothness improved without the stickiness peculiar to glycerin. When glycerin is used as a humectant in a cosmetic, since it forms micelles, hydration crystals and micelles remain as water evaporates, resulting in problems with usability. However, in a nano-disk emulsified cosmetic, a low-viscosity lamellar liquid crystal can be formed, improving the smoothness due to glycerin.

[0087] [Test Example 13] Effects of an oil-in-water emulsified cosmetic containing an elastomer Incidentally, the oil-in-water emulsified composition according to the present invention can also contain (F) an elastomer. Therefore, the inventors examined the usability of blending an elastomer as shown in Table 13. A panel of experts confirmed the stickiness in the same evaluation method as in Test Example 7.

[0088] [Table 13] (*4) Silicone KF-96A-6T (manufactured by Shin-Etsu Chemical Co., Ltd.) (*7) KF-96L-1.5CS (manufactured by Shin-Etsu Chemical Co., Ltd.) (*8) KF56A (manufactured by Shin-Etsu Chemical Co., Ltd.)

[0089] It was shown from Table 13 that when an elastomer was blended, a less sticky and smoother feel was obtained compared to the case where no elastomer was blended.

[0090] [Test Example 14] [Observation by Freeze Replica Electron Microscope (FF-TEM)] Freeze replica electron micrographs of nano-disk emulsification in FIGS. 8 and 9 in the following formulation are presented. The freeze replica electron microscope was performed using an H-8600 manufactured by Hitachi. The freeze replica was created using a BAF 400 manufactured by Hitachi. The frozen sample was cleaved under a high vacuum at -140 °C or lower, and platinum and carbon were vapor-deposited at an angle of 45 degrees. [Formulation] aqueous phase Water Remainder Ethyl Alcohol 2 mass% PEG-12 Dimethicone (HLB: 8) 1 mass% oil phase Silicone oil (*4) 3% by mass Hydrocarbon oil (*5) 3% by mass Polar oil (*6) 3% by mass (*4) Silicone KF-96A-6T (manufactured by Shin-Etsu Chemical Co., Ltd.) (*5) Nomcoat HP-30 (manufactured by Nisshin Oillio Group, Ltd.) (*6) RA-PE-408 (manufactured by Nippon Fine Chemical Co., Ltd.)

[0091] In FIGS. 7 and 8, it is shown that elliptical nanodisks surround the surface of the oil droplets. FIG. 9 shows a schematic diagram of the photographs shown in FIGS. 7 and 8.

[0092] Formulation Example 1: Cream (Formulation) (% by mass) Ion-exchanged water Balance Ethyl alcohol 5 Glycerin 10 1,3-Butylene glycol 5 Dipropylene glycol 3 Xanthan gum 0.07 (Sodium acrylate / sodium acryloyldimethyltaurine) copolymer 0.9 Isohexadecane 0.6 Polysorbate 80 0.2 Sorbitan oleate 0.06 Sodium N-stearoyl-N-methyltaurine 0.01 PEG-12 dimethicone (HLB8) 1 Pentaerythrityl tetra(2-ethylhexanoate) 12 Hydrogenated polydecene 5 Methylpolysiloxane 2 Tripropylene glycol dipivalate 1 Retinol Appropriate amount Tocopherol acetate 0.1 BHT Appropriate amount EDTA-3Na Appropriate amount Phenoxyethanol Appropriate amount

[0093] Formulation Example 2: Beauty Liquid (Formulation) (mass%) Ion-exchanged water Remainder Ethyl alcohol 5 Glycerin 5 1,3-Butylene glycol 4 PEG / PPG-14 / 7 dimethyl ether 1 Xanthan gum 0.05 Carbomer 0.45 Potassium hydroxide 0.2 Sodium N-stearoyl-N-methyltaurate 0.01 PEG-12 dimethicone (HLB8) 1 Triethylhexanoin 5 Cetyl ethylhexanoate 2 Isododecane 3 Methylpolysiloxane 4 Tranexamic acid 1 Dipotassium glycyrrhizinate 0.1 Sodium pyrosulfite Appropriate amount EDTA-3Na Appropriate amount Phenoxyethanol Appropriate amount Fragrance Appropriate amount

[0094] Formulation Example 3: Beauty Liquid (Formulation Example) (mass%) Ion-exchanged water Remainder Ethyl alcohol 5 Glycerin 15 1,3-Butylene glycol 10 Xanthan gum 0.05 (Acrylates / methacrylic acid steareth-20) copolymer 0.6 Sodium lauryl sulfate 0.003 Caustic potash 0.1 Sodium N-stearoyl-N-methyltaurate 0.01 PEG-12 dimethicone (HLB8) 1.5 Glyceryl diisostearate 5 Diisostearyl malate 3 Glyceryl Tri(caprylate / caprate) 3 Isohexadecane 2 Diphenylsiloxyphenyltrimethicone 1 Nicotinamide 5 EDTA-3Na q.s. Phenoxyethanol q.s. Fragrance q.s.

[0095] Formulation Example 4: Skin Lotion (Formulation) (mass%) Ion-exchanged water balance Ethyl alcohol 5 Glycerin 15 1,3-Butylene glycol 5 Xylitol 1 (Dimethylacrylamide / sodium acryloyldimethyltaurate) Crosspolymer 0.8 Sodium N-stearoyl-N-methyltaurate 0.01 PEG-12 Dimethicone (HLB8) 1.2 Meadowfoam oil 5 Methylpolysiloxane 5 Tripropylene glycol dipivalate 5 Diisopropyl sebacate 7 Retinol acetate 0.2 Tocopherol acetate 0.1 BHT q.s. EDTA-3Na q.s. Methylparaben q.s. Phenoxyethanol q.s. Fragrance q.s.

[0096] Formulation Example 5: Skin Lotion (Formulation) (mass%) Ion-exchanged water balance Ethyl alcohol 10 Glycerin 3 1,3-Butylene glycol 2 Dipropylene glycol 2 Erythritol 1 Saccharoglycan 0.5 Agar 0.4 N-Stearoyl-N-methyltaurine Na 0.01 PEG-12 Dimethicone (HLB5) 1 Glyceryl Diisostearate 3 Diisostearyl Malate 2 Tri(caprylic / capric) Glyceryl 2 Squalane 1 Methylpolysiloxane 2 Lauryl Glutamic Acid Di(phytosteryl / octyldodecyl) 1 Potassium 4-Toxysalicylate 1 2-O-Ethyl Ascorbic Acid 0.1 Sodium Pyrosulfite Appropriate amount EDTA-2Na Appropriate amount Methylparaben Appropriate amount Phenoxyethanol Appropriate amount Fragrance Appropriate amount

Claims

1. An oil-in-water emulsion composition comprising (A) an aqueous phase, (B) an oil phase, and (C) a polyoxyalkylene-modified silicone, (A) The total amount of monohydric alcohol and dihydric glycol in the aqueous phase is 1 to 35% by mass, with the monohydric alcohol alone being in the range of 1 to 15% by mass and the dihydric glycol alone being in the range of 1 to 20% by mass; (B) oil phase 1 to 50% by mass, (C) is 0.2 to 5 mass% based on the total composition, 1. An oil-in-water emulsion composition comprising:

2. 2. The oil-in-water emulsion composition according to claim 1, wherein the blending amount of component (C) is 0.2 to 2.5% by mass.

3. 3. The oil-in-water emulsion composition according to claim 1, wherein the proportion of the silicone oil in the oil phase (B) is 50% by mass or less.

4. 4. The oil-in-water emulsion composition according to claim 1, wherein the component (C) is PEG-12 dimethicone.

5. 5. The oil-in-water emulsion composition according to claim 1, wherein PEG-12 dimethicone does not dissolve in water but precipitates at a concentration of 5 to 20% by mass.

6. The oil-in-water emulsion composition according to any one of claims 1 to 5, wherein the PEG-12 dimethicone has an HLB value of less than 10 according to Griffin's formula.

7. 7. The oil-in-water emulsion composition according to any one of claims 1 to 6, wherein when the emulsion composition is centrifuged at 40,000 rpm for 60 minutes, a transparent layer separated at the bottom contains particles having an average particle size of 30 nm to 150 nm.

8. 8. The oil-in-water emulsion composition according to claim 1, wherein when the emulsion composition is centrifuged at 3,000 rpm for 16 hours, no transparent separation layer of oil, accounting for 2% of the total volume, is observed in either the upper or lower layer.

9. 9. The oil-in-water emulsion composition according to claim 1, wherein lamellar nanodisks are adsorbed at the oil-water interface.

10. 10. The oil-in-water emulsion composition according to claim 1, wherein the nanodisc has a major axis in the range of 20 nm to 1000 nm.

11. 2. The oil-in-water emulsion composition according to claim 1, further comprising, as component (D), one or more ionic surfactants selected from the group consisting of sulfosuccinic acid diester salts, alkyl allyl sulfonates, alkyl ether sulfonates, sulfosuccinic acid ester salts, acyl methyl taurine salts, and acyltaurine salts.

12. 12. The oil-in-water emulsion composition according to claim 11, wherein the ionic surfactant is an N-stearoyl-N-methyl taurine salt.

13. 13. The oil-in-water emulsion composition according to claim 11, wherein the content of the ionic surfactant (D) is 0.01 to 1.0% by mass based on the total mass of the oil-in-water emulsion composition.

14. 2. The oil-in-water emulsion composition according to claim 1, further comprising a polymer thickener as component (E) in a concentration of 0.05 to 1.0% by mass.

15. 15. The oil-in-water emulsion composition according to claim 14, wherein the polymeric thickener contained therein is a carboxyvinyl polymer or a derivative thereof.

16. 16. The oil-in-water emulsion composition according to claim 15, wherein the polymer thickener contained therein is an acrylic acid-based thickener.

17. The oil-in-water emulsion composition according to claim 16, wherein the acrylic acid-based thickener is one or more acrylic acid-based thickeners selected from the group consisting of dimethylacrylamide / sodium acryloyldimethyltaurate crosspolymer, ammonium acryloyldimethyltaurate / VP copolymer, ammonium acryloyldimethyltaurate beheneth-25 methacrylate crosspolymer, and sodium acrylate / sodium acryloyldimethyltaurate copolymer.

18. 2. The oil-in-water emulsion composition according to claim 1, further comprising an elastomer (F).

19. 2. The oil-in-water emulsion composition according to claim 1, wherein the monohydric alcohol is ethyl alcohol.

20. 2. The oil-in-water emulsion composition according to claim 1, wherein the divalent glycol is dipropylene glycol.

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