Vesicle composition, method for producing the same, and cosmetic base containing the vesicle composition

Abstract

Provided are: a vesicle composition having enhanced storage stability; a production method therefor; and a cosmetic base containing the vesicle composition.　The present invention provides a vesicle composition containing vesicles formed from water, a double-chain anionic surfactant, and a double-chain cationic surfactant.

Description

[Technical Field]

[0001] The present invention relates to a vesicle composition, a method for producing the same, and a cosmetic base containing the vesicle composition. [Background technology]

[0002] Amphiphilic compounds possessing both hydrophilic and hydrophobic properties include, for example, phospholipids, which form spherical vesicles consisting of bilayer membranes such as lamellae in an aqueous phase. Such bilayer membrane vesicles are called liposomes or vesicles, and can retain aqueous components within the vesicles and / or oily components within the vesicle membrane. For this reason, such vesicles are used as microcapsules in the pharmaceutical, cosmetic, and food industries, for example, due to advantages such as the ability to retain and administer drugs to the body and maintain their efficacy over a long period of time. Forming liposomes or vesicles allows for the production of compositions with excellent appearance, such as transparency, and therefore such vesicles are also expected to be used as cosmetic bases.

[0003] To date, many studies have been conducted on vesicles.

[0004] For example, Patent Document 1 discloses a vesicle containing 1) α,ε-bis(γ-N-(C10 to C30)acylglutamyl)lysine and / or a salt thereof, 2) ceramide and / or a derivative thereof, and 3) one or more selected from glycerin fatty acid esters, polyglycerin fatty acid esters, and pyroglutamic acid glycerin fatty acid esters.

[0005] Furthermore, Patent Document 2 discloses a vesicle composition characterized by containing the following components (a) to (e): (a) sodium dilauroyl glutamate lysine, (b) cholesterol and / or phytosterol, (c) monostearyl glycerin ether, (d) dipropylene glycol, and (e) water.

[0006] Patent Document 3 discloses that vesicles are formed in a liquid by mixing a cationic surfactant and an anionic surfactant molecule, and the cationic surfactant and anionic surfactant molecules used here are single-chain.

[0007] Patent Document 4 discloses that vesicles were formed by mixing a double-chain cationic surfactant with an anionic surfactant, and the anionic surfactant used here was a single-chain surfactant. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] International Publication No. 2008 / 149601 [Patent Document 2] Japanese Patent Application Laid-Open No. 2008-255109 [Patent Document 3] Japanese Patent Application Laid-Open No. 2008-056513 [Patent Document 4] Japanese Patent Application Laid-Open No. 2006-327849 Summary of the Invention [Problem to be solved by the invention]

[0009] However, vesicles using conventional surfactants are known to have a problem of insufficient storage stability. In particular, when vesicles are used as cosmetic bases, it has been desired to improve the storage stability and usability.

[0010] Therefore, the present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a stable vesicle composition, a method for producing the same, and a cosmetic base containing the stable vesicle composition. [Means for solving the problem]

[0011] The present inventors have found that the above problems can be solved by the following means.

[0012] <Aspect 1> Water, and Vesicles formed by double-chain anionic surfactants and double-chain cationic surfactants A vesicle composition comprising: <Aspect 2> 2. The vesicle composition according to aspect 1, wherein the vesicles have an average particle size of 150 nm or less. <Aspect 3> 3. The vesicle composition according to claim 1 or 2, wherein an oily component is retained in the vesicle. <Aspect 4> Aspect 4. The vesicle composition according to any one of Aspects 1 to 3, wherein the molar ratio of the double-chain anionic surfactant to the double-chain cationic surfactant is 8:2 to 5:5. <Aspect 5> Aspect 5. The vesicle composition according to any one of Aspects 1 to 4, wherein the double-chain anionic surfactant has two alkyl or acyl groups each having 8 to 20 carbon atoms. <Aspect 6> Aspect 6. The vesicle composition according to any one of Aspects 1 to 5, wherein the double-chain cationic surfactant has two alkyl or acyl groups each having 8 to 20 carbon atoms. <Aspect 7> 7. The vesicle composition according to any one of Aspects 1 to 6, wherein the double-chain anionic surfactant is sodium dilauroyl glutamate lysine. <Aspect 8> Aspect 8. The vesicle composition according to any one of Aspects 1 to 7, wherein the double-chain cationic surfactant is distearyldimethylammonium chloride. <Aspect 9> A cosmetic base comprising the vesicle composition according to any one of aspects 1 to 8. <Aspect 10> A method for producing the vesicle composition according to any one of Aspects 1 to 8, comprising mixing an alcohol solution in which the double-chain anionic surfactant and the double-chain cationic surfactant are dissolved with water to form the vesicle. <Aspect 11> A method for producing the vesicle composition according to any one of Aspects 1 to 8, comprising dissolving the double-chain anionic surfactant and the double-chain cationic surfactant in water to form the vesicle. [Effects of the Invention]

[0013] According to the present invention, it is possible to provide a vesicle composition having improved storage stability, a method for producing the same, and a cosmetic base containing the vesicle composition. [Brief explanation of the drawings]

[0014] [Figure 1] FIG. 1 is a phase diagram of a DLGLS-DSAC-water system based on the molar ratio of DSAC (double-chain cationic surfactant) to DLGLS (double-chain anionic surfactant). [Figure 2] FIG. 2 shows the results of Cryo-TEM observation of the vesicles obtained in Example 1. DETAILED DESCRIPTION OF THE INVENTION

[0015] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below with reference to the preferred embodiments. However, the present invention is not limited to the following embodiments, and various modifications can be made within the scope of the present invention.

[0016] Vesicle Composition The vesicle composition of the present invention comprises: Water, and Vesicles formed by double-chain anionic surfactants and double-chain cationic surfactants Includes:

[0017] As a result of intensive research, the present inventors have found that vesicles are formed by mixing a double-chain anionic surfactant and a double-chain cationic surfactant in a specific molar ratio, and have completed the present invention by using vesicles formed from such double-chain anionic surfactant and double-chain cationic surfactant.

[0018] <Vesicles> The vesicles of the present invention can be formed from a double-chain anionic surfactant and a double-chain cationic surfactant.

[0019] The average particle size of the vesicles is not particularly limited and may be, for example, 500 nm or less. By controlling the average particle size of the vesicles, the vesicle composition can be adjusted to be translucent or transparent. Therefore, from the viewpoint of imparting transparency to the vesicle composition, the average particle size of the vesicles of the present invention may be 150 nm or less, 120 nm or less, 100 nm or less, 95 nm or less, 90 nm or less, 85 nm or less, 80 nm or less, 75 nm or less, 70 nm or less, or 60 nm or less. The lower limit of the average particle size of the vesicles is not particularly limited and may be 20 nm or more or 50 nm or more. The average particle size of the vesicles can be measured by dynamic light scattering, for example, using a Zetasizer Nano ZS (manufactured by Sysmex).

[0020] In the present invention, the average particle size of the vesicles can be controlled by adjusting the molar ratio of the double-chain anionic surfactant and the double-chain cationic surfactant capable of forming vesicles.

[0021] The following provides an example of vesicle formation by adjusting the molar ratio of sodium dilauroyl glutamate lysine (hereinafter also abbreviated as "DLGLS") as a double-chain anionic surfactant and distearyldimethylammonium chloride (hereinafter also abbreviated as "DSAC") as a double-chain cationic surfactant.

[0022] Figure 1 shows the phase diagram of the DLGLS-DSAC-water system depending on the molar ratio of DSAC (double-chain cationic surfactant) to DLGLS (double-chain anionic surfactant). As shown in Figure 1, when the molar ratio of DLGLS to DSAC is 0:10, i.e., in a DSAC and water system, the melting point (T1) of DSAC is approximately 34°C. At temperatures below this melting point (T1), the system is in a hydrated crystalline state. At temperatures above the melting point (T1), DSAC melts and the system is in a lamellar crystalline state (denoted by "Lα"). As the molar ratio of DLGLS increases, the melting point further decreases. For example, it can be seen that the melting point continues to decrease when the molar ratio of DLGLS to DSAC is in the range of 1:9 to 4:6. Furthermore, at temperatures below the melting point for each molar ratio, the system is in a hydrated crystalline state. At temperatures above the melting point, the system is in a hexagonal lattice state (represented by "H2"), a mixed state of lamellar crystalline and hydrated crystalline states (represented by "Lα+α-form"), or a lamellar crystalline state ("Lα"). Surprisingly, when the molar ratio of DLGLS to DSAC becomes 5:5, the melting point of DSAC disappears and vesicles (represented by "Lα'") are formed in the system. Furthermore, vesicles in this system continue to exist up to a certain range of the molar ratio of DLGLS to DSAC, and their presence can be confirmed until the molar ratio of DLGLS to DSAC reaches approximately 8:2. When the molar ratio of DLGLS to DSAC exceeds 8:2 and reaches 10:0, vesicles disappear, and the system becomes a micellar state (represented by "L1").

[0023] Thus, the formation of vesicles by mixing a double-chain anionic surfactant and a double-chain cationic surfactant in a specific molar ratio was demonstrated in the DLGLS-DSAC-water system.

[0024] Even more surprisingly, the average particle size of the vesicles thus formed can be controlled to be uniform and smaller than the average particle size of vesicles reported so far.

[0025] Furthermore, the above-mentioned DLGLS and DSAC are highly safe for the skin, and therefore vesicles formed from them are preferable in that they can be used as cosmetic bases.

[0026] Furthermore, as shown in Figure 1, in the absence of DLGLS, it is difficult to stably disperse DSAC in water at around room temperature, and it is difficult to form vesicles unless heat above the melting point is applied. In contrast, the present invention makes it possible to form vesicles that are stable even at around room temperature by mixing DLGLS and DSAC in a specific molar ratio (8:2 to 5:5). From this perspective, the vesicles of the present invention are stable even at around room temperature and can be suitably used as a cosmetic base.

[0027] The Pellicer-DLGLS-water system described above is merely an example system, and it is presumed that other double-chain anionic surfactants and double-chain cationic surfactants will also have similar tendencies in controlling vesicle formation and average vesicle particle size by adjusting the molar ratio. However, it should be understood that other systems of double-chain anionic surfactants and double-chain cationic surfactants that can form vesicles do not necessarily match the specific molar ratio of DLGLS to DSAC in the DLGLS-DSAC-water system.

[0028] In the present invention, the molar ratio of the double-chain anionic surfactant to the double-chain cationic surfactant (double-chain anionic surfactant:double-chain cationic surfactant) may be, for example, 8:2 to 5:5, 7.5:2.5 to 5:5, 7:3 to 5:5, or 7:3 to 6:4.

[0029] Furthermore, in order to form the vesicles of the present invention, the total amount of the double-chain anionic surfactant and the double-chain cationic surfactant may be, for example, 0.1% by mass or more, 0.2% by mass or more, or 0.3% by mass or more, relative to the total amount of the composition, from the viewpoint of vesicle formation and stability, and may be 10% by mass or less, or 5% by mass or less.

[0030] Furthermore, as described above, in the present invention, vesicles can be formed by mixing a double-chain anionic surfactant and a double-chain cationic surfactant in a specific molar ratio, so that a "formation aid" to aid vesicle formation, as in the past, does not need to be added, or it may be added in a lower ratio than in the past. Thus, when a formation aid is added to form the vesicles of the present invention, the mass ratio of the total amount of the double-chain anionic surfactant and the double-chain cationic surfactant to the formation aid may be 1:0.0005 or less.

[0031] In the present invention, whether or not vesicles are formed can be confirmed by, for example, Cryo-TEM observation.

[0032] (double-chain anionic surfactant) In the present invention, the term "anionic surfactant" can include agents or compounds that exhibit the properties of anionic surfactants based on their chemical structure. Furthermore, the term "double-chain surfactant" refers to a surfactant having two alkyl or acyl groups each having 8 or more carbon atoms, and the two chains may be the same or different, independently of each other.

[0033] The double-chain anionic surfactant according to the present invention preferably has two alkyl or acyl groups having 8 to 20 carbon atoms, and more preferably has two alkyl groups having 12 to 18 carbon atoms. The double-chain anionic surfactant according to the present invention has a carboxyl group, which allows it to have anionic properties.

[0034] The double-chain anionic surfactant of the present invention may be a di-fatty acid acyl glutamate lysine salt. Here, examples of di-fatty acid acyl glutamate lysine salts include, but are not limited to, dilauroyl glutamate lysine salt, dimyristoyl glutamate lysine salt, distearoyl glutamate lysine salt, and dilinoleoyl glutamate lysine salt. In addition, examples of these salts include, but are not limited to, alkali metal salts such as sodium salts and potassium salts.

[0035] More specifically, the double-chain anionic surfactant according to the present invention is preferably sodium dilauroyl glutamate lysine.

[0036] The double-chain anionic surfactant according to the present invention may be obtained by synthesis, or a commercially available product may be used.

[0037] Commercially available double-chain anionic surfactants include, but are not limited to, Pellicer L-30 (sodium dilauroyl glutamate lysine) manufactured by Asahi Kasei Chemicals Corporation.

[0038] (double-chain cationic surfactant) In the present invention, the term "cationic surfactant" can include agents or compounds that exhibit the properties of a cationic surfactant due to their chemical structure.

[0039] The double-chain cationic surfactant according to the present invention preferably has two alkyl or acyl groups having 8 to 20 carbon atoms, and more preferably has two alkyl groups having 12 to 18 carbon atoms.

[0040] The double-chain cationic surfactant according to the present invention may be a double-chain cationic surfactant represented by the following general formula (I): [ka] In the formula, R1 and R2 each independently represent an alkyl group having 8 to 20 carbon atoms, R3 and R4 each independently represent an alkyl group having 1 to 3 carbon atoms, a hydroxyl group, or a benzyl group, and X represents a halogen atom.

[0041] In general formula (I), R1 and R2 each independently represent an alkyl group having 8 to 20 carbon atoms, and preferably an alkyl group having 12 to 18 carbon atoms.

[0042] In general formula (I), R3 and R4 each independently represent an alkyl group having 1 to 3 carbon atoms, a hydroxyl group, or a benzyl group, and preferably represent an alkyl group having 1 to 3 carbon atoms.

[0043] In addition, in the general formula (I), X represents a halogen atom, preferably a Br atom or a Cl atom, and more preferably a Cl atom.

[0044] More specifically, the double-chain cationic surfactant according to the present invention is preferably distearyldimethylammonium chloride.

[0045] The double-chain cationic surfactant according to the present invention may be obtained by synthesis, or a commercially available product may be used.

[0046] Properties of the Vesicle Composition The vesicle composition of the present invention may be transparent, translucent, or opaque. However, when used as a cosmetic base requiring a transparent appearance, it is preferably transparent or translucent. Here, "transparent or translucent" means that the cosmetic has an L value of 50 or more in the Hunter Lab color system. The L value represents transparency, where the transparency of purified water is 100 and the complete absence of light transmission is 0. In other words, the closer the L value is to 100, the higher the transparency. Therefore, the vesicle composition of the present invention preferably has an L value of 50 or more. More specifically, the L value is preferably 50.0 or more, 60.0 or more, 70.0 or more, 80.0 or more, 90.0 or more, 92.0 or more, 94.0 or more, 96.0 or more, 98.0 or more, or 100.0. The L value can be measured, for example, using a spectrophotometer SE7700 (manufactured by Nippon Denshoku Industries Co., Ltd.).

[0047] The pH value of the vesicle composition of the present invention is not particularly limited, but when used as a cosmetic base, it may be 6.80 or more, 7.00 or more, 7.10 or more, 7.20 or more, 7.30 or more, 7.40 or more, 7.50 or more, 7.60 or more, 7.70 or more, 7.80 or more, 7.85 or more, 7.90 or more, 7.91 or more, 7.92 or more, 7.93 or more, 7.94 or more, 7.95 or more, 7.96 or more, 7.97 or more, 7.98 or more, 7.99 or more, 8.00 or more, or 8.10 or more, or 8.50 or less. The pH value is measured at a temperature of 30°C.

[0048] <Uses of the vesicle composition> The vesicle composition of the present invention can encapsulate drugs and the like in both the hydrophobic and hydrophilic parts of the vesicle, and can therefore be used as a cosmetic base, agrochemical, drug delivery, pharmaceutical, ink, and the like.

[0049] (Cosmetic base) The vesicle composition of the present invention can be used as a cosmetic base to be applied to the skin, etc. Thus, the present invention provides a cosmetic base comprising the vesicle composition of the present invention.

[0050] Examples of cosmetics include skin care cosmetics such as lotions, moisturizing gels, massage gels, beauty serums, and emulsions, makeup cosmetics, sun care products, hair cosmetics such as hair styling agents and hair gels, and hair dyes. The vesicle composition of the present invention can be used appropriately depending on the form and properties of these cosmetics. For example, when a translucent or transparent lotion is desired, it is preferable to use a vesicle composition of the present invention containing vesicles with an average particle size of 150 nm or less.

[0051] <water> In the vesicle composition of the present invention, the water content is not particularly limited, but from the viewpoint of vesicle formability, it may be 70% by mass or more, or 75% by mass or more, and may be 95% by mass or less, 90% by mass or less, or 80% by mass or less, based on the total composition.

[0052] <Oily ingredients> In the vesicle composition of the present invention, an oily component may be retained within the vesicle, i.e., within the bilayer membrane of the vesicle. The oily component that can be retained within the vesicle is not limited to, but at least one selected from the group consisting of polar oils and silicone oils can be used. The oily component that can be retained within the vesicle can be appropriately selected based on the IOB value, etc. For example, when using vesicles formed with a silicone surfactant, it is preferable to use at least one selected from the group consisting of polar oils and silicone oils with an IOB value of 0.05 to 0.80, from the viewpoint of vesicle stability. Here, the IOB value of the oily component can be calculated using a known calculation method based on its structure.

[0053] The oily component may be contained in an amount of 10% by mass or less, preferably 10.0% by mass or less, 9.0% by mass or less, 8.0% by mass or less, 7.0% by mass or less, 6.0% by mass or less, 5.0% by mass or less, or 4.0% by mass or less, or 0.5% by mass or more, 1.0% by mass or more, 2.0% by mass or more, or 3.0% by mass or more. The oily component may be contained in an amount of 0.001% by mass or more, 0.005% by mass or more, 0.01% by mass or more, 0.05% by mass or more, or 0.1% by mass or more, or 1.0% by mass or less, 0.5% by mass or less, or 0.3% by mass or less, based on the total amount of the vesicle composition. The vesicle composition of the present invention can also be used in combination with polar oils having an IOB value other than 0.05 to 0.80, or non-polar oils such as mineral oil, as long as the stability of the vesicles is not impaired.

[0054] (polar oil) Examples of polar oils include isostearic acid, isopropyl myristate, cetyl octanoate, octyldodecyl myristate, isopropyl palmitate, butyl stearate, hexyl laurate, myristyl myristate, decyl oleate, hexyldecyl dimethyloctanoate, isononyl isononanoate, cetyl lactate, myristyl lactate, lanolin acetate, isocetyl stearate, isocetyl isostearate, cetyl ethylhexanoate, cholesteryl 12-hydroxystearate, and ethylene di-2-ethylhexanoate. Glycol, dipentaerythritol fatty acid ester, N-alkyl glycol monoisostearate, neopentyl glycol dicaprate, diisostearyl malate, glycerin di-2-heptylundecanoate, trimethylolpropane tri-2-ethylhexanoate, trimethylolpropane triisostearate, pentaerythritol tetra-2-ethylhexanoate, glyceryl tri-2-ethylhexanoate (triethylhexanoin), trimethylolpropane triisostearate, cetyl isooctanoate, cetyl 2- Ethylhexanoate, 2-ethylhexyl palmitate, alkyl benzoate (12-15 carbon atoms), cetearyl isononanoate, tri(caprylic / capric)glycerin, (dicaprylic / capric) butylene glycol, glycerin trimyristate, tri-2-heptylundecanoic acid glyceride, castor oil fatty acid methyl ester, oleyl oleate, cetostearyl alcohol, acetoglyceride, 2-heptylundecyl palmitate, diisobutyl adipate, N-lauroyl-L-glutamic acid Examples of the polar oil include 2-octyldodecyl ester, di-2-heptylundecyl adipate, ethyl laurate, di-2-ethylhexyl sebacate, 2-hexyldecyl myristate, 2-hexyldecyl palmitate, 2-hexyldecyl adipate, diisopropyl sebacate, di-2-ethylhexyl succinate, ethyl acetate, butyl acetate, amyl acetate, triethyl citrate, 2-ethylhexyl paramethoxycinnamate, tripropylene glycol dipivalate, and 2-ethylhexyl 2-cyano-3,3-diphenylacrylate. One or more polar oils may be used in combination.

[0055] (silicone oil) Silicone oil is not particularly limited as long as it is an oily component having polysiloxane structure, and can be any of linear structure or cyclic structure, volatile or non-volatile.As silicone oil, can be listed chain silicone such as dimethylpolysiloxane, methylphenylpolysiloxane, methylhydrogenpolysiloxane, etc., cyclic silicone such as octamethylcyclotetrasiloxane, decamethylcyclopentasiloxane, dodecamethylcyclohexasiloxane, etc., and these can be used alone or in combination of two or more.

[0056] Among these silicone oils, volatile cyclic silicone oils, particularly octamethylcyclotetrasiloxane and decamethylcyclopentasiloxane, can be preferably used.By using such volatile cyclic silicone oils, it is possible to incorporate more fragrance components into the vesicle bilayer membrane, and when the vesicle composition is used as an external preparation, it is less sticky and provides an excellent feeling of use.As non-volatile silicone oils, it is particularly preferable to use diphenylsiloxyphenyl trimethicone, methylphenyl polysiloxane, etc.

[0057] <Other ingredients> The vesicle composition of the present invention can be appropriately blended with various components depending on the intended use of the composition, etc., to the extent that the formability and stability of the vesicles are not affected. Examples of the various components include additives that are typically blended into cosmetics, such as lower alcohols, polyhydric alcohols, various extracts, humectants, antioxidants, buffers, preservatives, colorants, fragrances, chelating agents, pH adjusters, and ultraviolet absorbers. Depending on their properties, the various components can be blended into the aqueous phase serving as the continuous phase in the vesicle composition, the aqueous phase serving as the dispersed phase within the vesicles, or the oil phase serving as the dispersed phase within the vesicle bilayer membrane.

[0058] The aqueous phase may contain water-soluble drugs applicable to pharmaceuticals, quasi-drugs, cosmetics, etc., as well as any aqueous components typically used in pharmaceuticals or cosmetics, etc., in amounts that do not affect the stability of the vesicles. In particular, from the viewpoint of vesicle stabilization or usability, it is preferable that the aqueous component be one or more selected from ethanol and polyols.

[0059] Examples of polyols include ethylene glycol, propylene glycol, 1,3-butylene glycol, tetramethylene glycol, glycerin, sorbitol, diethylene glycol, dipropylene glycol, tetramethylene glycol, diglycerin, polyethylene glycol, and polypropylene glycol, with propylene glycol, dipropylene glycol, and 1,3-butylene glycol being particularly preferred. One or more aqueous components selected from ethanol and polyols may be blended in an amount of 1 to 20% by mass, or 3 to 10% by mass, based on the total amount of the composition.

[0060] <<Method for producing vesicle composition>> The present invention also provides a method for producing a vesicle composition. The vesicle composition of the present invention can be produced by the following method 1 or method 2.

[0061] <Method 1> The method for producing the vesicle composition of the present invention comprises the steps of: The method includes mixing an alcohol solution in which a double-chain anionic surfactant and a double-chain cationic surfactant are dissolved with water to form vesicles.

[0062] Here, the double-chain anionic surfactant and the double-chain cationic surfactant may be dissolved together in the alcohol solution, or may be dissolved separately in their own alcohol solutions and then mixed. In the present invention, the mixing operation may include an appropriate stirring operation.

[0063] Furthermore, when the double-chain anionic surfactant and the double-chain cationic surfactant are dissolved in the alcohol solution, the dissolution may be carried out at room temperature or may be carried out with moderate heating.

[0064] The alcohol to be used is not particularly limited, and may be, for example, a monohydric alcohol such as methanol or ethanol, or a dihydric alcohol such as dipropylene glycol.

[0065] When the alcohol solution in which the double-chain anionic surfactant and the double-chain cationic surfactant are dissolved is mixed with water, the alcohol solution in which the double-chain anionic surfactant and the double-chain cationic surfactant are dissolved in water may be added, or water may be added to the alcohol solution in which the double-chain anionic surfactant and the double-chain cationic surfactant are dissolved, but the former is preferred.

[0066] Furthermore, when other components are to be blended, they may be mixed in water or in an alcohol solution in which a double-chain anionic surfactant and a double-chain cationic surfactant are dissolved, but this may be done appropriately depending on the properties of the components to be blended. For example, when an oily component is to be blended in the vesicle, it is preferable to mix the oily component in an alcohol solution in which a double-chain anionic surfactant and a double-chain cationic surfactant are dissolved.

[0067] In this production method, an alcohol solution containing a double-chain anionic surfactant and a double-chain cationic surfactant is mixed with water, and vesicles composed of the double-chain anionic surfactant and the double-chain cationic surfactant are spontaneously formed in the aqueous phase. When an oily component is contained together with the double-chain anionic surfactant and the double-chain cationic surfactant, the oily component is solubilized and incorporated into the bilayer membrane of the formed vesicles.

[0068] <Method 2> The method for producing the vesicle composition of the present invention comprises the steps of: The method includes dissolving a double-chain anionic surfactant and a double-chain cationic surfactant in water to form vesicles.

[0069] Here, the double-chain anionic surfactant and the double-chain cationic surfactant may be dissolved together in water, or may be dissolved separately in water and then mixed.

[0070] Furthermore, when the double-chain anionic surfactant and the double-chain cationic surfactant are dissolved in water, the dissolution may be carried out at room temperature or by moderate heating.

[0071] In this production method, an alcohol solution in which a double-chain anionic surfactant and a double-chain cationic surfactant are dissolved is mixed with water, and vesicles composed of the double-chain anionic surfactant and the double-chain cationic surfactant are spontaneously formed in the aqueous phase. [Example]

[0072] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these. Unless otherwise specified, the blending amounts are expressed in mass %.

[0073] Example 1 In Example 1, the formation of vesicles when the molar ratio of sodium dilauroyl glutamate lysine to distearyldimethylammonium chloride was 6:4 was confirmed by observation at 30,000 magnification using a Cryo-TEM (JEM-2200FS, camera DE-20, manufactured by JEOL). The observation temperature was cryo (-175±1.7°C). The results are shown in Figure 2.

[0074] The components contained in the vesicle composition of Example 1 are as follows: Ingredients Mass% Purified water 89.18% by mass Dipropylene glycol (DPG) 10% by mass Pellicer L-30 (Asahi Kasei Chemicals Corporation) 0.72% by mass (Actual component: 0.216% by mass) Distearyldimethylammonium chloride (DSAC) 0.1% by mass

[0075] As is clear from FIG. 2, in Example 1, vesicles were formed that had a shape resembling the cross section of an onion.

[0076] Examples 2 to 4 and Comparative Examples 1 to 3 Composition samples of Examples 2 to 4 and Comparative Examples 1 to 3 were produced based on the formulations shown in Table 1 below and the production methods described below.

[0077] <Production Methods of Examples 2 to 4> Compositions of Examples 2 to 4 were prepared according to the following procedures 1 to 5: 1. (1) to (7) shown in Table 1 were mixed at room temperature and dissolved. 2. (10) and (9) shown in Table 1 were mixed under heating, dissolved at 80°C, and then cooled to 40°C. 3. (11) to (14) shown in Table 1 were mixed at room temperature and dissolved. 4. The products obtained in steps 2 and 3 above were mixed by stirring. 5. The products obtained in steps 1 and 4 above were mixed by stirring.

[0078] <Production Methods of Comparative Examples 1 to 3> Compositions of Comparative Examples 1 to 3 were prepared according to the following procedures 1 to 5: 1. (1) to (7) shown in Table 1 were mixed at room temperature and dissolved. 2. (8) and (9) shown in Table 1 were mixed under heating, dissolved at 80°C, and then cooled to 40°C. 3. (11) to (14) shown in Table 1 were mixed at room temperature and dissolved. 4. The products obtained in steps 2 and 3 above were mixed by stirring. 5. The products obtained in steps 1 and 4 above were mixed by stirring.

[0079] <evaluation> (Measurement of average particle size) The average particle size of vesicles or vesicle-equivalents in the compositions obtained in each of the Examples and Comparative Examples was measured by dynamic light scattering using a Zetasizer Nano ZS (manufactured by Sysmex). The results are shown in Table 1.

[0080] (Measurement of L value) The L value of the compositions obtained in each of the Examples and Comparative Examples was measured using a spectrophotometer SE7700 (manufactured by Nippon Denshoku Industries Co., Ltd.) The results are shown in Table 1.

[0081] (pH measurement) The pH value of the compositions obtained in each of the Examples and Comparative Examples was measured using a pH meter F-52 (manufactured by Horiba, Ltd.) The results are shown in Table 1.

[0082] The compositions obtained in each of the Examples and Comparative Examples were stored for one month under the temperature conditions of 0°C, 25°C, 37°C, and 50°C, and then the L values ​​were measured using a spectrophotometer SE7700 (manufactured by Nippon Denshoku Industries Co., Ltd.) The results are shown in Table 1.

[0083] [Table 1]

[0084] As shown in Table 1, all of Examples 2 to 4 were able to form vesicles, and furthermore, the L value after one month of storage was similar to that before storage, indicating excellent storage stability.

[0085] In contrast, the particles obtained in Comparative Example 1 had an average particle size of 8.2 nm, and were presumably micelles rather than vesicles.

[0086] Furthermore, the product obtained in Comparative Example 2 had an average particle size of 249.1 nm, a low L value, and low transparency (almost opaque), so it is presumed to have been an emulsion or suspension rather than a vesicle.

[0087] In Comparative Example 3, the product obtained had an average particle size of 8.2 nm, which suggests that it was not a vesicle but a micelle. In other words, Comparative Example 3, which used a single-chain cationic surfactant, was unable to form vesicles.

[0088] <Formulation example of vesicle composition> Examples of cosmetic formulations based on the vesicle composition of the present invention are given below, but the present invention is not limited to these examples.

[0089] <Formulation example 1: Transparent whitening lotion> Ingredients Mass% 1. Remaining purified water 2. EDTA-2Na 2H2O 0.03 3. Tranexamic acid 2.0 4. Glycerin 3.0 5. 1,3-Butylene Glycol 7.0 6. Phenoxyethanol 0.5 7. Sodium citrate 0.05 8. Triethanolamine 0.05 9. Dipropylene glycol 8.0 10. Distearyldimethylammonium chloride 0.1 11. Ethanol 3.0 12. Sodium dilauramidoglutamide lysine 0.72 13. Lavender oil 0.1

[0090] The resulting whitening lotion had emulsified particles of 71 nm, a pH of 8.13, and an L value of 97.

[0091] <Formulation example 2: Thick lotion> Ingredients Mass% 1. Remaining purified water 2. EDTA-2Na 2H2O 0.03 3. (Acryloyldimethyltaurate ammonium methacrylate beheneth-25) crosspolymer 0.45 4. Glycerin 3.0 5. 1,3-Butylene Glycol 7.0 6. Phenoxyethanol 0.5 7. Sodium citrate 0.05 8. Triethanolamine 0.05 9. Dipropylene glycol 8.0 10. Distearyldimethylammonium chloride 0.1 11. Ethanol 3.0 12. Sodium dilauramidoglutamide lysine 0.72 13. Lavender oil 0.1

[0092] The resulting thick lotion had a viscosity of 85 mPa·s and a pH of 7.84.

[0093] The viscosity was evaluated using a B-type viscometer (TVB-type viscometer TVB-10, manufactured by Toki Sangyo Co., Ltd.) under the conditions of rotor number M2, 30°C, and 12 revolutions per minute.

Claims

1. Water, and Vesicles formed by double-chain anionic surfactants and double-chain cationic surfactants A vesicle composition comprising:

2. The vesicle composition according to claim 1, wherein the average particle size of the vesicles is 150 nm or less.

3. The vesicle composition according to claim 1 or 2, wherein an oily component is retained in the vesicle.

4. 4. The vesicle composition according to claim 1, wherein the molar ratio of the double-chain anionic surfactant to the double-chain cationic surfactant is 8:2 to 5:

5.

5. 5. The vesicle composition according to claim 1, wherein the double-chain anionic surfactant has two alkyl or acyl groups each having 8 to 20 carbon atoms.

6. The vesicle composition according to any one of claims 1 to 5, wherein the double-chain cationic surfactant has two alkyl or acyl groups each having 8 to 20 carbon atoms.

7. The vesicle composition according to any one of claims 1 to 6, wherein the double-chain anionic surfactant is sodium dilauroyl glutamate lysine.

8. The vesicle composition according to any one of claims 1 to 7, wherein the double-chain cationic surfactant is distearyldimethylammonium chloride.

9. A cosmetic base comprising the vesicle composition according to any one of claims 1 to 8.

10. A method for producing the vesicle composition according to any one of claims 1 to 8, comprising mixing an alcohol solution in which the double-chain anionic surfactant and the double-chain cationic surfactant are dissolved with water to form the vesicle.

11. A method for producing the vesicle composition according to any one of claims 1 to 8, comprising dissolving the double-chain anionic surfactant and the double-chain cationic surfactant in water to form the vesicle.

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