Oil-based emulsions in water

Abstract

The problem addressed by the present invention is to provide a composition containing nanodiscs composed of a silicone-based surface active agent in which the stability of an emulsion composition is improved.　In order to solve the aforementioned problem, provided is an oil-in-water emulsion composition containing (A) a water phase, (B) an oil phase, and (C) a polyoxyalkylene-modified silicone, and said oil-in-water emulsion composition contains (A) 1-35 mass% of ethyl alcohol and dipropylene glycol, combined, in the water phase, (B) 1-50 mass% of the oil phase, and (C) 0.2-5 mass% of the polyoxyalkylene-modified silicone in terms of the entire composition, and thus nanodiscs are formed and a stable emulsion state is obtained.

Description

Related Applications

[0001] The present invention is based on the priority of Japanese Patent Application No. 2020-036519 (filed March 4, 2020), the entire contents of which are incorporated herein by reference. [Technical Field]

[0002] The present invention relates to a nanodisk emulsion composition and a method for producing the same, and in particular to improving emulsion stability and usability with respect to emulsification using a nanodisk emulsion composition comprising a silicone surfactant. [Background technology]

[0003] Among amphiphilic compounds possessing both hydrophilic and hydrophobic properties, some, such as phospholipids, form spherical vesicles consisting of bilayer membranes (lamellar phases) in an aqueous phase. These bilayer membrane vesicles are called liposomes or vesicles, and can stably retain aqueous components within the vesicles or oily components within the vesicle membrane. For this reason, when drugs are administered to the body, their metabolism is suppressed, and medicinal efficacy can be maintained for a long period of time. For this reason, they are used as microcapsules in the pharmaceutical, cosmetic, and food industries. On the other hand, nanodiscs, which do not contain an internal phase, are plate-like dispersions of a lamellar liquid crystal phase. While they can stably retain oily components within the vesicle membrane, they do not contain an internal phase.

[0004] Patent Documents 1 and 2 disclose that vesicles are formed by using a specific polyoxyethylene hydrogenated castor oil derivative as an amphiphilic substance, and that by including this as an emulsifier, a non-sticky cosmetic product with a good feel when used is obtained. Silicone surfactants have also been reported as amphiphilic compounds capable of forming such vesicles (see, for example, Patent Documents 3 to 7). Vesicles formed using silicone surfactants are characterized by the fact that they can be prepared more easily than when other surfactants with vesicle-forming properties are used. Patent Document 7 discloses a technology for dispersing a water-insoluble liquid phase into an external phase using vesicles that encapsulate the internal phase. However, emulsification using vesicles is unstable and has limitations in practical use, so the amount of vesicles used tends to be large, and as is commonly known, stickiness caused by vesicle-forming activators can sometimes be an issue. Furthermore, there have been no reports of forming nanodisks using silicone surfactants.

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

[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, KanakoNishimura, Yoriko Mune, Yuji Matsushita, Ayano Nakamura, Koji Tsuchiya, HidekiSakai, Heinz Hoffmann, High Skin Hydration and Comfortable Texture of a MoisturizingLotion Fulfilled by Controlling the Phase Sequence of a Vesicle / MicelleComplex, J. Soc. Cosmet. Chem. Jpn., 52, (4) 260-268 (2018) Summary of the Invention [Problem to be solved by the invention]

[0007] Conventional vesicle emulsions have not been found to have sufficient stability over time or over temperature. The present invention was made in consideration of the problems of the conventional technology, and its purpose is to improve the stability of emulsion compositions by using nanodiscs rather than vesicles containing an internal phase. [Means for solving the problem]

[0008] In order to solve the problems of the conventional technology, the present inventors conducted extensive research and found that by optimizing the vesicles that serve as nanodisk precursors in an oil-in-water emulsion composition containing an aqueous phase, an oil phase, and a specific silicone surfactant, silicone nanodisks that do not contain an internal phase are formed and adsorb to the oil-water interface, thereby maintaining emulsion stability, leading to the completion of the present invention.

[0009] When the emulsion composition is centrifuged at 40,000 rpm for 60 minutes, particles with an average particle size of 30 nm to 150 nm are present in the transparent layer that separates into the lower layer, and when the emulsion composition is centrifuged at 3,000 rpm for 16 hours, the proportion of particles in the total volume is 2%. EndIt is characterized by the absence of a transparent oily separation layer in the upper or lower layers. [Effects of the Invention]

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

[0011] [Figure 1] FIG. 1 is a diagram showing the peak particle size of particles contained in the aqueous phase before emulsification in an insoluble state (0% by mass of alcohol). [Figure 2] This is a graph showing the peak particle size of particles contained in the lower aqueous phase after emulsification in an insoluble state (alcohol content: 0 mass %, oil content: 10 mass %) and centrifuging the emulsion at 40,000 rpm for 60 minutes. [Figure 3] FIG. 1 is a diagram showing the peak particle size of particles contained in the aqueous phase before emulsification in a micellar state (alcohol content: 20% by mass). [Figure 4] This is a graph showing the peak particle size of particles contained in the lower aqueous phase after emulsification in a micellar state (alcohol content: 20% by mass, oil content: 10% by mass) and centrifuging the emulsion at 40,000 rpm for 60 minutes. [Figure 5] FIG. 1 is a diagram showing the peak particle size of particles contained in the aqueous phase before emulsification in a vesicle state (alcohol content: 10% by mass). [Figure 6] This is a graph showing the peak particle size of particles contained in the lower aqueous phase after emulsification in a state where vesicles have been transformed into nanodiscs (alcohol content: 10% by mass, oil content: 10% by mass), and centrifuging the emulsion at 40,000 rpm for 60 minutes. [Figure 7] This is an electron microscope image of the interface between oil particles and water in a nanodisc emulsion. [Figure 8] This is an electron microscope photograph showing a magnified image of nanodiscs adsorbed on the interface of a nanodisc emulsion. [Figure 9]FIG. 1 is a schematic diagram showing the transfer and adsorption of vesicles to nanodiscs at the interface. DETAILED DESCRIPTION OF THE INVENTION

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

[0013] The nanodiscs of the present invention, in an oil-free composition, are vesicles, which are precursors to nanodiscs. These vesicles are not spontaneous vesicles. Spontaneous vesicles refer to a solution in equilibrium, i.e., a vesicle-dispersed state when stored at a constant temperature and pressure for an extremely long period of time. The vesicles of the present invention are in equilibrium, a two-phase solution of planar lamellar liquid crystals and water. When this state is dispersed by applying a strong stirring force, they become vesicles. When oil is added to the vesicle state and emulsified, the vesicles undergo a structural transformation into nanodiscs. Furthermore, adding an ionic surfactant as a dispersant makes it possible to maintain this state for a long period of time. This completes the present invention.

[0014] The oil-in-water emulsion composition of the present invention, produced by adsorption onto nanodisks, is characterized by the inclusion of a monohydric alcohol or a dihydric glycol. Examples of monohydric alcohols include ethyl alcohol, normal propyl alcohol, and isopropyl alcohol. Examples of dihydric glycols include 1,3-butylene glycol and dipropylene glycol. These compounds convert surfactants containing polyether-modified silicones to hydrophilic properties through their solvent effect (Non-Patent Document 1). As a result, they promote the transition from vesicles, which are spherical endoplasmic reticulum, to nanodisks. While the entire surface of vesicles, which are spherical endoplasmic reticulum, is covered with hydrophilic groups, nanodisks are difficult to form in water because their edges are lipophilic groups. Monohydric alcohols and dihydric glycols hydrophilize surfactants through their solvent effect, facilitating their transition to nanodisks. On the other hand, when dissolving PEG-12 dimethicone in alcohol, trivalent glycerin, tetravalent sorbitol, etc. are undesirable because they make the surfactant lipophilic and inhibit its transfer to nanodiscs, and it is desirable that the blending amount be (total amount of monovalent alcohol and divalent glycol) > (total amount of trivalent glycerin and tetravalent sorbitol). (A) Aqueous phase In the aqueous phase, the total amount of the monohydric alcohol and dihydric glycol in the aqueous phase may be 1 to 45% by mass, preferably 1 to 35% by mass, but it is preferable that the monohydric alcohol alone is in the range of 1 to 15% by mass, and the dihydric glycol alone is in the range of 1 to 20% by mass. The monohydric alcohol is preferably ethyl alcohol, and the dihydric glycol is preferably dipropylene glycol. More preferably, the ethyl alcohol and dipropylene glycol are blended at an upper limit of the concentration that satisfies the following [Formula 1]. [Formula 1] Ethyl alcohol concentration in aqueous phase (mass%) / 15 + dipropylene glycol concentration in aqueous phase (mass%) / 20≦1

[0015] If the amount of ethyl alcohol alone, the amount of dipropylene glycol alone, or the total amount of ethyl alcohol and dipropylene glycol is less than 1% by mass, vesicles may not be generated or the structure may be disrupted, making it impossible to emulsify. If the amount of ethyl alcohol alone exceeds 15% by mass or the amount of dipropylene glycol alone exceeds 20% by mass, or if the ratio of ethyl alcohol and dipropylene glycol is outside the range of [Formula 1] above, or if the total amount exceeds 35% by mass even within the range of [Formula 1] above, the vesicle membrane may become too flexible or the vesicles may transition to micelles, preventing the stabilizing effect.

[0016] (B) Oil phase The oil component that can be blended into the oil phase is not particularly limited, but examples thereof 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.); Oil (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 esters, monoisostearin N-Alkyl Glycol Dicaprate, Neopentyl Glycol Dicaprate, Diisostearyl Malate, Glycerin Di-2-heptylundecanoate, Trimethylolpropane Tri-2-ethylhexanoate, Trimethylolpropane Triisostearate, Glycerin Trioctanoate, Glycerin Triisopalminate, Trimethylolpropane Triisostearate, Cetyl-2-ethylhexanoate, 2-Ethylhexyl Palmitate, Glycerin Trimyristate, Tri-2-heptylundecanoate Glyceride, Examples of suitable oleic acid esters include maize oil fatty acid methyl esters, 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, and triethyl citrate.

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

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

[0019] [ka] (In the formula, R 1 is hydrogen or an alkyl group having 1 to 6 carbon atoms, and at least one of A is a group represented by 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 a polyoxyalkylene group of at least 5 or more, and the other A's are hydrogen or alkyl groups 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] Commercially available PEG-12 dimethicone products include DOWSIL ES-5373 (manufactured by Dow-Toray), SH3772M, SH3773M, and SH3775M (all of which are Dow Toray ), IM-22 (manufactured by Wacker Chemical Co.), etc.

[0022] The amount of component (C) must be sufficient to form vesicles, which are precursors of nanodiscs, and is 0.2 to 5.0% by mass, preferably 0.5 to 2.5% by mass, of the total composition. If the amount is less than 0.2% by mass, the effects of the nanodiscs may not be obtained, and if it exceeds 5.0% by mass, the stability of the nanodiscs may be reduced.

[0023] The oil-in-water emulsion composition of the present invention contains nanodiscs made of a surfactant (C). Vesicles, which are precursors of nanodiscs, can be formed by known methods. For example, the aqueous phase (A) and the component (C) can be mixed and stirred to form vesicles made of the component (C) in the aqueous phase. The average particle size of the vesicles is approximately 30 nm to 150 nm.

[0024] The oil-in-water emulsion composition of the present invention can further contain an ionic surfactant (D). The addition of an ionic surfactant improves the stability of the nanodisk-containing composition (C) made of polyoxyalkylene-modified silicone. The ionic surfactant used in the present invention is not particularly limited as long as it is other than the silicone surfactant (C) and exhibits ionic properties.

[0025] The amount of (D) ionic surfactant is preferably 0.01 to 1.0% by mass, and more preferably 0.01 to 0.1% by mass, of the total composition. If the amount of surfactant is too small, the stabilizing effect of the nanodisks may not be sufficient, while if the amount is too large, it may have adverse effects, such as solubilizing the vesicles that are the precursors of nanodisks or inhibiting nanodisk formation. The blending ratio of (C) polyoxyalkylene-modified silicone to ionic surfactant is preferably 1:0.01 to 1:0.1.

[0026] The ionic surfactant (D) that can be blended in the present invention can be an anionic surfactant, but if the Krafft point of the anionic surfactant is low (for example, below room temperature), the silicone surfactant and the anionic surfactant will mix easily, and the interaction will inhibit the transition from vesicles to nanodiscs. This is because anionic surfactants have a strong tendency to form aggregates called spherical micelles, and when they coexist with vesicles, they have the effect of maintaining the spherical structure and inhibiting the transition to nanodiscs.

[0027] As the ionic surfactant (D) that can be blended in the present invention, among anionic surfactants, sulfonate-type anionic surfactants are preferred. Examples of sulfonate-type anionic surfactants include sulfosuccinate diester salts, alkylarylsulfonates, alkyl ether sulfonates, sulfosuccinate ester salts, acylmethyltaurine salts, and acyltaurine salts.

[0028] In the present invention, it is particularly preferable to incorporate an N-acylmethyltaurine salt as the ionic surfactant. Among the N-acylmethyltaurine salts represented by the following general formula (2), N-stearoyl-N-methyltaurine salt is more preferable.

[0029] [ka] (2)

[0030] In the present invention, a polymeric thickener (E) can also be blended. The polymeric thickener (E) is preferably a carboxyvinyl polymer or a derivative thereof, or an acrylic acid-based thickener. Among these, one or more selected from the group consisting of a carboxyvinyl polymer, a (dimethylacrylamide / sodium acryloyldimethyltaurate) crosspolymer, an (ammonium acryloyldimethyltaurate / VP) copolymer, an (ammonium acryloyldimethyltaurate / beheneth-25 methacrylate) crosspolymer, and a (sodium acrylate / sodium acryloyldimethyltaurate) copolymer are preferred.

[0031] (E) The polymer thickener can be blended depending on the desired usability of the formulation, but is preferably blended in an amount of 0.05 to 1.0% by mass based on the total oil-in-water emulsion composition.

[0032] In the present invention, a silicone elastomer (F) may also be blended. When silicone elastomers are added to compositions such as cosmetics, they can provide users with a smooth and elegant feel when used. Examples of silicone elastomers include silicone elastomers (organopolysiloxanes). Silicone elastomers include, for example, cross-linked silicones (cross-linked organopolysiloxanes) in which silicone polymers are three-dimensionally cross-linked. The use of silicone elastomers can suppress stickiness and provide a smooth (smooth) feel when applied to the skin.

[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 silicone elastomers include dimethicone crosspolymer, dimethicone / vinyl dimethicone crosspolymer, dimethicone / phenylvinyl dimethicone crosspolymer, vinyl dimethicone / lauryl dimethicone crosspolymer, lauryl polydimethylsiloxyethyl dimethicone / bis-vinyl dimethicone crosspolymer, alkyl (C30-45) cetearyl dimethicone crosspolymer, cetearyl dimethicone crosspolymer, etc.

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

[0035] Glycerin can also be added to impart the "smoothness upon application" desired by consumers as a cosmetic product. Normally, a high content of glycerin results in a sticky feeling and poor usability. However, in the present invention, even with a high content of glycerin, a smooth feel can be achieved without stickiness.

[0036] The method for producing an oil-in-water emulsion composition according to the present invention comprises a vesicle-forming step of mixing (A) an aqueous phase with (C) a polyoxyalkylene-modified silicone to form vesicles, and may further comprise a step of adding an ionic surfactant to the vesicle-containing aqueous solution obtained by the above step.

[0037] In the method for producing an oil-in-water 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 to nanodiscs. Here, the aqueous phase (A) is not particularly limited as long as it is a formulation in which water and an aqueous solvent (a monohydric alcohol and / or a dihydric glycol) are the main media, and in addition to water or an aqueous solvent, ingredients typically used in cosmetics may be blended in amounts that do not impair the stability of the nanodiscs.

[0038] (C) Polyoxyalkylene-modified silicone is dissolved in advance in the monohydric alcohol and / or dihydric glycol that are components of the (A) aqueous phase, and then mixed with water, the remaining component of the (A) aqueous phase, to form vesicles, which are precursors of nanodisks made of polyoxyalkylene-modified silicone, in the aqueous phase. By adding oil to an aqueous phase containing vesicles, which are precursors of nanodiscs, and stirring, the vesicles, which are precursors of nanodiscs, are transferred to and adsorbed onto nanodiscs at the oil-water interface, thereby completing the present invention.

[0039] The oil-in-water emulsion composition of the present invention can be suitably used, for example, as a cosmetic. When used as a cosmetic, in addition to the above-mentioned essential components, ingredients typically used in pharmaceuticals and cosmetics can be blended in amounts that do not impair the stability. Furthermore, the nanodisk-containing composition can be blended with oils in amounts that cannot be blended with conventional solubilizers, yet the composition is less sticky and provides a refreshing feel when used. The other formulation components may be blended in advance in the aqueous phase before vesicle formation, or may be blended in the formulation after vesicle formation.

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

[0041] The present invention will be described in more detail below with reference to examples of the present invention, but the present invention is not limited to these. Unless otherwise specified, the blending amounts are expressed in mass %.

[0042] [Test Example 1] Preparation of vesicles, precursors of nanodiscs, and conditions for vesicle formation The inventors prepared the aqueous phase components shown in Tables 1-1 and 1-2 by a standard method, mixed them with PEG-12 dimethicone, and had experts visually evaluate the results and measure the average particle size. The average particle size was measured using a Zetasizer (Malvern Pamalytical's Zetasizer Nano ZS).

[0043] [Evaluation method] A: The average particle size at room temperature (25°C) is 30 nm to 150 nm, and the pale blue appearance indicates the presence of vesicles. B: The average particle size at room temperature (25°C) is less than 30 nm, and it is colorless and transparent and judged to be a micelle. C: The average particle size at room temperature (25°C) is greater than 150 nm but less than 250 nm, and the substance is cloudy and contains aggregates, making it insoluble.

[0044] [Table 1-1] (*1) DOWSIL ES-5373 (manufactured by Dow Toray)

[0045] [Table 1-2] (*1) DOWSIL ES-5373 (manufactured by Dow Toray)

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

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

[0048] [Table 2] (*1) DOWSIL ES-5373 (manufactured by Dow Toray) (*2) DOWSIL SH 3775 M (Dow Toray) (*3) DOWSIL SH 3771 M (Dow Toray)

[0049] When the HLB of PEG-12 dimethicone is 5, vesicles, which are precursors to nanodiscs, 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 to nanodiscs, are formed when the concentration of ethyl alcohol is 2.5 to 10% by mass. Furthermore, when the HLB of PEG-12 dimethicone is 13, regardless of the content of ethyl alcohol, vesicles, which are precursors to nanodiscs, are not formed, and micelles are formed. Furthermore, As is clear from Table 2, PEG-12 Dimethicone HLB 8 or less, and the ethyl alcohol content is 5% by mass less than In this case, PEG-12 dimethicone is not soluble in the aqueous phase.

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

[0051] (Condition evaluation method) The evaluation was carried out as follows. A: In appearance, creaming was observed immediately after application and over a period of 4 weeks, but no significant coalescence or enlargement of the emulsion particles was observed under an optical microscope. B: Separation of oil is observed in appearance, and coalescence of emulsified particles is observed under an optical microscope.

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

[0053] Table 3 shows that stable blending is possible up to about 50% by mass of oil. Furthermore, although not shown in the table, when the oil content exceeds 60% by mass, a small amount of oil begins to float. It was shown that silicone oil alone can be blended stably up to about 30% by mass.

[0054] [Test Example 4] Furthermore, the inventors investigated the type and amount of oil used. The results are shown in Table 4. The evaluation method was the same as in Test Example 3.

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

[0056] Table 4 shows that when the oil content in the water / oil blend is 50% by mass or less, if the silicone oil content in the oil exceeds 70% by mass, coalescence of the emulsified particles is observed and separation of the oil occurs. When the silicone oil content in the oil is 50% by mass or less, creaming is observed from immediately after emulsification over a period of 4 weeks, but no coalescence or separation of the oil is observed. Furthermore, no significant coalescence or enlargement of the emulsified particles is observed under an optical microscope, demonstrating that a stable blend is possible.

[0057] [Test Example 5] Examination of emulsifying power depending on oil type The inventors investigated whether there was 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: When observed under an optical microscope, the rate of change in oil particle size (particle size over time / initial particle size) 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 rate of change is greater than 1.2 or less than 0.8.

[0058] [Table 5] TIFF0007762137000009.tif85166(*1) DOWSIL ES-5373 (Dow Toray Industries, Inc.) (*4) Silicone KF-96A-6T (Shin-Etsu Chemical Co., Ltd.) (*7) KF-96L-1.5CS (Shin-Etsu Chemical Co., Ltd.) (*8) KF56A (Shin-Etsu Chemical Co., Ltd.)

[0059] The results in Table 5 show that oils that are highly compatible with PEG-12 dimethicone with an HLB of 10 or less and difficult to emulsify are in the order of silicone oil > hydrocarbon oil > polar oil. Therefore, it can be said that the order of highest emulsion stability is polar oil > hydrocarbon oil > silicone oil. It was shown that emulsion stability tends to worsen when there is a high amount of oil that is highly compatible with the surfactant.

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

[0061] After preparing the aqueous phase according to the formulation shown in Table 6, oil was added. Homogenizer The emulsion composition was centrifuged (3000 rpm, 16 hours) and the peak particle size of the supernatant was measured using a Zetasizer Nano ZS manufactured by Malvern Pamalytical. The results of the peak particle size of the aqueous phase before emulsification are shown in Figure 1. 1 ,figure 3 ,figure 5 The peak values ​​after emulsification and centrifugation are shown in the figure. 2 ,figure 4 ,figure 6 Shown below.

[0062] [Table 6] (*4) Silicone KF-96A-6T (Shin-Etsu Chemical Co., Ltd.) (*5) Nomcoat HP-30 (manufactured by Nisshin Oillio Group Co., Ltd.) (*6) RA-PE-408 (Nippon Fine Chemical Co., Ltd.)

[0063] In Test Example 6, Test Example 6-1 is shown in FIG. 1 and Figure 2 This shows that when the ethyl alcohol content is 0% by mass, PEG-12 dimethicone does not dissolve in the aqueous phase and remains in an insoluble state. No significant change in the peaks before and after emulsification is observed. In Test Example 6-2, as shown in Figures 4 and 5, micelles are formed when the alcohol content is 20% by mass, and no significant change in the peaks before and after emulsification is observed. Since most PEG-12 dimethicone is in a micellar state, it was shown that at the oil-water interface, the micelles are deformed and cleaved to form a monomolecular adsorption layer and emulsify. On the other hand, Test Example 6-3 is shown in Fig. 5 and Figure 6Therefore, when the ethyl alcohol content is 10% by mass, vesicles, which are precursors to nanodiscs, are formed before emulsification. Vesicles are usually smaller than 1 micron, the size of emulsified particles, and larger than 10 nm, the size of micelles. In this system, particles of approximately 30 nm to 200 nm are formed, indicating that they are vesicles. Non-Patent Document 2 also discloses the formation of vesicles in this composition. After emulsification, it is believed that the emulsion is stabilized by the adsorption of nanodiscs, which are deformed structures of vesicles, to the oil-water interface.

[0064] [Test Example 7] Stability and usability under various conditions The emulsified state was divided into insoluble (PEG-12 dimethicone is not dissolved in the aqueous phase), nanodisc (nanodisc precursor vesicles are formed), and micelle (PEG-12 dimethicone is in the form of micelles in the aqueous phase), and the stability and usability of each state were examined. For the insoluble, nanodisc, and micelle formulations, the aqueous phase was prepared using water, ethyl alcohol, and PEG-12 dimethicone as shown in Table 7, and then oil was added. Homogenizer (7000 rpm, 3 minutes) to prepare an emulsion composition. The evaluation method for each item is shown below, and the results are shown in Table 7.

[0065] (Method for evaluating the stability of centrifugation) The emulsion was centrifuged at 3,000 rpm for 16 hours and at 40,000 rpm for 1 hour, and the changes in particle size were observed and evaluated using an optical microscope. A: There was no change in the emulsion particle size. B: The emulsion particle size changed, but no changes in shape such as separation were observed. C: Separation occurred and the formulation was no longer viable. (Method for evaluating penetration sensation) Seven expert panels will evaluate the effects of applying this test product to the skin and classify it as follows based on the number of panels who answered "It feels like it penetrates into the skin." A: 5 or more people B: 3~4 people C:0~2 people (Method for evaluating elongation during application) Seven expert panels applied the test product to the skin and evaluated its effect as follows. The number of panels who answered "it spreads well on the skin" was used to classify the product as follows: A: 5 or more people B: 3~4 people C:0~2 people (Method for evaluating stickiness after application) Seven expert panels applied the test product to the skin and evaluated its effect as follows. The number of panels who answered "not sticky" was categorized as follows: If there are any other distinctive features, please add them. A: 5 or more people B: 3~4 people C:0~2 people

[0066] [Table 7] (*4) Silicone KF-96A-6T (Shin-Etsu Chemical Co., Ltd.) (*5) Nomcoat HP-30 (manufactured by Nisshin Oillio Group Co., Ltd.) (*6) RA-PE-408 (Nippon Fine Chemical Co., Ltd.)

[0067] From the results of Table 7 in Test Example 7, it can be seen that the stability and usability were better in the state where nanodisks were formed as shown in Test Example 7-2 than in other states.

[0068] [Test Example 8] The nanodisk emulsion composition according to the present invention is suitable for incorporation into cosmetics. The inventors investigated the amount of PEG-12 dimethicone to be added to cosmetics. The results are shown in Table 8. The appearance and usability were evaluated as follows.

[0069] (Condition evaluation method) The evaluation was carried out as follows. A: In appearance, creaming was observed immediately after application and over a period of 4 weeks, but no significant coalescence or enlargement of the emulsion particles was observed under an optical microscope. B: Separation of oil is observed in appearance, and coalescence of emulsified particles is observed under an optical microscope. (Method for evaluating elongation during application) Seven expert panels applied the test product to the skin and evaluated its effects as follows. The results were categorized according to the number of panelists who answered, "The product spreads smoothly without sticking to the fingers during application." A: 5 or more people B: 3~4 people C:0~2 people (Method for evaluating stickiness after application) Seven expert panels applied the test product to the skin and evaluated its effect as follows. The number of panels who answered "not sticky" was categorized as follows: A: 5 or more people B: 3~4 people C:0~2 people

[0070] [Table 8] (*5) Nomcoat HP-30 (manufactured by Nisshin Oillio Group Co., Ltd.) (*6) RA-PE-408 (Nippon Fine Chemical Co., Ltd.) (*7) KF-96L-1.5CS (Shin-Etsu Chemical Co., Ltd.) (*8) KF56A (Shin-Etsu Chemical Co., Ltd.) (*9) Eldew PS-203R (Ajinomoto Co., Inc.)

[0071] Table 8 shows that the feel of the cosmetic composition when it contains more than 0.6% by mass of PEG-12 dimethicone is good. It also shows that the feel of the cosmetic composition when it contains more than 0.8% by mass of PEG-12 dimethicone is even better.

[0072] [Test Example 9] The inventors have investigated the amount of ionic surfactant to be added to cosmetics. The results are shown in Table 9. To confirm the stability, the emulsion was stored at 50°C for one week, and then the state of the emulsion particles was observed under an optical microscope.

[0073] (Evaluating changes in emulsion particle size) A: There was no change in the emulsion particle size. B: The emulsion particle size changed, but no changes in shape such as separation were observed. C: Separation occurred and the formulation was no longer viable.

[0074] [Table 9] (*5) Nomcoat HP-30 (manufactured by Nisshin Oillio Group Co., Ltd.) (*7) KF-96L-1.5CS (Shin-Etsu Chemical Co., Ltd.) (*8) KF56A (Shin-Etsu Chemical Co., Ltd.)

[0075] Table 9 shows that the stability of the formulation is good when the amount of the ionic surfactant is blended in the range of 0.01 to 0.1% by mass.

[0076] [Test Example 10] The inventors have investigated the effect of combining polyoxyalkylene-modified silicone with an anionic surfactant. The usability and stability were evaluated as follows. The emulsion particle size was observed using an optical microscope. The results are shown in Table 10.

[0077] (Usability evaluation criteria) A: 9 to 10 out of 10 expert panel members rated it as non-sticky B: Seven or eight out of ten expert panel members rated it as non-sticky C: 4 to 6 out of 10 expert pals rated it as non-sticky D: Three or fewer of the ten expert panel members rated it as non-sticky. (Stability evaluation criteria) A: The average particle size after storage at 50°C for 2 weeks remains unchanged from the particle size immediately after preparation. B: The average particle size after storage at 50°C for 2 weeks is less than 1.1 times the particle size immediately after preparation. C: The average particle size after storage at 50°C for 2 weeks is 1.1 or more and less than 1.5 times the particle size immediately after preparation. D: The average particle size after storage at 50°C for 2 weeks is 1.5 or more of the particle size immediately after preparation.

[0078] [Table 10] (*9) Amisoft HS21 (manufactured by Ajinomoto Co., Inc.)

[0079] As can be seen from Table 10, when evaluating the anionic surfactants two weeks after sample preparation, a formulation amount or conditions that do not inhibit nanodisc formation are required. In the case of sodium N-stearoyl-N-methyl taurate, ease of use and stability were maintained even at 0.6% by mass, while disodium N-stearoyl-L-glutamate showed no effect on either ease of use or stability. These results suggest that sodium N-stearoyl-N-methyl taurate does not affect nanodisc formation. On the other hand, disodium N-stearoyl-L-glutamate inhibits nanodisc formation. A formulation of 0.01% by mass of sodium N-stearoyl-N-methyl taurate demonstrated superior stability compared to 0.6% by mass.

[0080] [Test Example 11] The inventors have investigated the amount of thickener to be added to cosmetics. The methods for evaluating appearance and usability are shown below, and the results are shown in Table 11.

[0081] (Condition evaluation method) A: No creaming or other abnormalities were observed in appearance immediately after application or over a period of 4 weeks. B: Changes in condition such as creaming are observed over time (4 weeks). (Method for evaluating the refreshing feeling during application) Seven expert panels applied the test product to the skin and evaluated its effect as follows. The number of panels who answered "I felt refreshed" was categorized as follows: A: 5 or more people B: 3~4 people C:0~2 people

[0082] [Table 11] (*4) Silicone KF-96A-6T (Shin-Etsu Chemical Co., Ltd.) (*7) KF-96L-1.5CS (Shin-Etsu Chemical Co., Ltd.)

[0083] As shown in Table 11, in the test examples in which creaming did not occur, it was shown that a refreshing feel could be obtained regardless of the type of thickener used.

[0084] [Test Example 12] The inventors investigated the feel when a high amount of glycerin was blended as a moisturizing agent in a nanodisc emulsion cosmetic. The results are shown in Table 12. The sticky feeling after application was evaluated in the same manner as in Test Example 7. The smoothness was compared with that of Test Example 12-1. In the test example, PEG-12 dimethicone dissolved in ethyl alcohol was added to an aqueous phase containing water and glycerin to form vesicles that serve as nanovesicle precursors. An oil phase was then added to this aqueous phase to prepare an emulsion composition. However, glycerin can also be added after PEG-12 dimethicone dissolved in ethyl alcohol has been added to the aqueous phase containing water.

[0085] [Table 12] (*4) Silicone KF-96A-6T (Shin-Etsu Chemical Co., Ltd.) (*7) KF-96L-1.5CS (Shin-Etsu Chemical Co., Ltd.)

[0086] Table 12 shows that the smoothness is improved without the stickiness that is characteristic of glycerin. When glycerin is used as a moisturizing agent in cosmetics, there are usability issues because, in the case of micelles, hydrated crystals and micelles remain as the water evaporates. However, in nanodisk emulsion cosmetics, low-viscosity lamellar liquid crystals are formed, and the use of glycerin improves smoothness.

[0087] [Test Example 13] Effect of oil-in-water emulsion cosmetics containing elastomer The oil-in-water emulsion composition of the present invention may also contain an elastomer (F). Therefore, the inventors investigated the usability of the composition by incorporating an elastomer, as shown in Table 13. The stickiness was evaluated by a panel of experts in the same manner as in Test Example 7.

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

[0089] Table 13 shows that the incorporation of elastomer results in a less sticky and more refreshing feel than the incorporation of elastomer.

[0090] [Test Example 14] [Frozen replica electron microscope (FF-TEM) observation] Figure for the following prescription 7 and Figure 8 Here, we present frozen replica electron micrographs of nanodisk emulsions. The frozen replica electron microscope was performed using a Hitachi H-8600. The frozen replicas were created using a Hitachi BAF 400. The frozen samples were fractured under high vacuum at temperatures below -140°C, and platinum and carbon were vapor-deposited at a 45-degree angle. <Prescription> aqueous phase water residue ethyl alcohol 2% by mass PEG-12 Dimethicone (HLB: 8) 1% by 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 (Shin-Etsu Chemical Co., Ltd.) (*5) Nomcoat HP-30 (manufactured by Nisshin Oillio Group Co., Ltd.) (*6) RA-PE-408 (Nippon Fine Chemical Co., Ltd.)

[0091] figure 7 and Figure 8 In Fig. 1, elliptical nanodisks surround the surface of the oil droplet. 9 is a figure 7 ,figure 8 The photograph shown in is shown in a schematic diagram.

[0092] Prescription example 1: Cream (Formulation) (% by mass) Ion-exchanged water residual Ethyl alcohol 5 Glycerin 10 1,3-butylene glycol 5 Dipropylene Glycol 3 Xanthan gum 0.07 (Sodium acrylate / sodium acryloyldimethyltaurate) copolymer 0.9 Isohexadecane 0.6 Polysorbate 80 0.2 Sorbitan oleate 0.06 Sodium N-stearoyl-N-methyl taurate 0.01 PEG-12 Dimethicone (HLB8) 1 Pentaerythritol tetra 2-ethylhexanoate 12 Hydrogenated Polydecene 5 Methylpolysiloxane 2 Tripropylene glycol dipivalate 1 Retinol (appropriate amount) Tocopheryl acetate 0.1 BHT moderate amount EDTA-3Na appropriate amount Phenoxyethanol (appropriate amount)

[0093] Prescription example 2: Beauty serum (Formulation) (% by mass) Ion-exchanged water residual 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-methyl taurate 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] Prescription example 3: Beauty serum (Formulation example) (mass%) Ion-exchanged water residual Ethyl alcohol 5 Glycerin 15 1,3-butylene glycol 10 Xanthan gum 0.05 (Acrylates / steareth-20 methacrylate) copolymer 0.6 Sodium lauric sulfate 0.003 Caustic potash 0.1 Sodium N-stearoyl-N-methyl taurate 0.01 PEG-12 Dimethicone (HLB8) 1.5 Glyceryl Diisostearate 5 Diisostearyl Malate 3 Caprylic / Capric Triglyceride 3 Isohexadecane 2 Diphenylsiloxyphenyl Trimethicone 1 Nicotinamide 5 EDTA-3Na appropriate amount Phenoxyethanol (appropriate amount) Fragrance (appropriate amount)

[0095] Prescription example 4: Beauty serum (Formulation) (% by mass) Ion-exchanged water residual Ethyl alcohol 5 Glycerin 15 1,3 Butylene Glycol 5 Xylitol 1 (Dimethylacrylamide / Sodium Acroyldimethyltaurate) Crosspolymer 0.8 Sodium N-stearoyl-N-methyl taurate 0.01 PEG-12 Dimethicone (HLB8) 1.2 Meadowfoam oil 5 Methylpolysiloxane 5 Tripropylene glycol dipivalate 5 Diisopropyl Sebacate 7 Retinol acetate 0.2 Tocopheryl acetate 0.1 BHT moderate amount EDTA-3Na appropriate amount Methylparaben (appropriate amount) Phenoxyethanol (appropriate amount) Fragrance (appropriate amount)

[0096] Prescription example 5: Beauty serum (Formulation) (% by mass) Ion-exchanged water residual Ethyl alcohol 10 Glycerin 3 1,3-butylene glycol 2 Dipropylene Glycol 2 Erythritol 1 Succinoglycan 0.5 Agar 0.4 Sodium N-stearoyl-N-methyl taurate 0.01 PEG-12 Dimethicone (HLB5) 1 Glyceryl Diisostearate 3 Diisostearyl malate 2 Caprylic / Capric Triglyceride 2 Squalane 1 Methylpolysiloxane 2 Phytosteryl / Octyldodecyl Lauroyl Glutamate 1 4-Toxisalicylic acid potassium salt 1 2-0-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 the monohydric alcohol and the dihydric glycol in the aqueous phase is 1 to 35% by mass, with the monohydric alcohol alone being 1 to 15% by mass and the dihydric glycol alone being 1 to 20% by mass; (B) oil phase 1 to 50% by mass, (C) is contained in an amount of 0.2 to 5% by mass based on the total mass of the composition; Each of these includes An oil-in-water emulsion composition characterized in that lamellar nanodisks are adsorbed at the oil-water interface.

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 silicone oil in the oil phase (B) is 50% by mass or less.

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

5. 5. The oil-in-water emulsion composition according to claim 4, wherein the PEG-12 dimethicone has an HLB of less than 10 according to Griffin's formula.

6. 3. The oil-in-water emulsion composition according to claim 1, wherein when the emulsion composition is centrifuged at 40,000 rpm for 60 minutes, a transparent layer separates from the lower layer and contains particles having an average particle size of 30 nm to 150 nm.

7. 3. 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% or more of the total volume, is observed in either the upper or lower layer.

8. 3. The oil-in-water emulsion composition according to claim 1, wherein the nanodiscs have a major axis in the range of 20 nm to 1000 nm.

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