Method for selecting emulsifier for three phase emulsification, emulsifier for three phase emulsification, three phase emulsion, and three phase emulsification method

Abstract

To provide a method for selecting an emulsifier for three phase emulsification having stable emulsifying ability to an oil kind to be emulsified, the emulsifier for three phase emulsification, a three phase emulsion using the emulsifier, and a three phase emulsification method.SOLUTION: The method for selecting the emulsifier for three-phase emulsification comprises selecting the emulsifier for three-phase emulsification having ≥1,500 light scattering intensity at 25°C of a dispersion obtained by dispersing 2 mass% of the emulsifier in an oily substance to be three-phase emulsified.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a method for selecting an emulsifier for three-phase emulsification, an emulsifier for three-phase emulsification, a three-phase emulsion, and a three-phase emulsification method. [Background technology]

[0002] The three-phase emulsification method is a method of emulsifying by attaching a three-phase emulsifier to the surface of the internal phase by van der Waals forces, and differs from surfactant-based emulsification methods that use amphiphilic surfactants that have both hydrophilic and hydrophobic properties to reduce interfacial tension.

[0003] For example, Patent Document 1 describes a water-in-oil (W / O) emulsion containing inverted vesicles formed from a sucrose fatty acid ester as an emulsifier, the emulsion also containing a nonionic surfactant other than the sucrose fatty acid ester. In Patent Document 1, the emulsion stability of the water-in-oil (W / O) emulsion obtained by a three-phase emulsification method using inverted vesicles formed from a sucrose fatty acid ester as an emulsifier is evaluated by visually observing the emulsified state of the emulsion after it has been left to stand for a predetermined period of time.

[0004] However, not limited to the technology disclosed in Patent Document 1, emulsion stability must be confirmed solely after the preparation of a three-phase emulsion. Generally, emulsifiers used in three-phase emulsification are assumed to be hydrophilic nanoparticles that are insoluble in both water and oil. However, depending on the type of oil, some emulsifiers may appear to be stable at the beginning of emulsification but dissolve these hydrophilic nanoparticles over time. If the hydrophilic nanoparticles that should have been present at the oil-water interface dissolve, the emulsion naturally becomes unstable, and ultimately the emulsion itself cannot be maintained. The present invention proposes, using indicators, the physical properties that an emulsifier to be used for a specific oil type must possess in order to maintain a stable emulsion before three-phase emulsification. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2012-16668 Summary of the Invention [Problem to be solved by the invention]

[0006] Therefore, the present invention can provide a method for selecting an emulsifier for three-phase emulsification that has stable emulsification ability for the type of oil to be emulsified, an emulsifier for three-phase emulsification, a three-phase emulsion using the emulsifier, and a three-phase emulsification method. [Means for solving the problem]

[0007] [1] A method for selecting an emulsifier for three-phase emulsification, which selects an emulsifier for three-phase emulsification that has a light scattering intensity (DLS) of 1500 or more at 25°C when dispersed at 2% by mass in an oily substance to be emulsified. [2] An emulsifier for three-phase emulsification of a three-phase emulsion, wherein the dispersion obtained by dispersing the emulsifier for three-phase emulsification in an oily substance constituting the oil phase at 2% by mass exhibits a light scattering intensity of 1500 or more at 25°C. [3] The emulsifier for three-phase emulsion according to [2] above, which is at least one of closed vesicles formed by an amphiphilic substance that spontaneously forms closed vesicles in an aqueous system and particles of a polycondensation polymer having hydroxyl groups. [4] A three-phase emulsion using an emulsifier for three-phase emulsification, in which the dispersion obtained by dispersing the emulsifier at 2% by mass in the oily substance to be emulsified exhibits a light scattering intensity of 1500 or more at 25°C. [5] A three-phase emulsification method using an emulsifier for three-phase emulsification, the dispersion obtained by dispersing the emulsifier at 2% by mass in an oily substance to be emulsified into three phases, has a light scattering intensity of 1500 or more at 25°C. [Effects of the Invention]

[0008] According to the present invention, it is possible to provide a method for selecting an emulsifier for three-phase emulsification, an emulsifier for three-phase emulsification, a three-phase emulsion using the emulsifier, and a three-phase emulsification method, which allow extremely efficient and reliable identification and selection of an emulsifier that brings about stable emulsification for any oil to be emulsified. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, a detailed description will be given based on an embodiment.

[0010] As a result of extensive research, the present inventors have found that the light scattering intensity at 25°C of a dispersion obtained by dispersing an emulsifier for three-phase emulsification in an oily substance to be three-phase emulsified, being within a specified range, is an indicator for determining the emulsion stability of a three-phase emulsion, and have completed the present invention based on this finding.

[0011] First, a method for selecting an emulsifier for three-phase emulsification according to an embodiment will be described.

[0012] In the embodiment, the method for selecting an emulsifier for three-phase emulsification is to select an emulsifier for three-phase emulsification that has a light scattering intensity of 1500 or more at 25°C when dispersed at 2% by mass in an oily substance to be three-phase emulsified.

[0013] In the method for selecting an emulsifier for three-phase emulsions according to the embodiment, an emulsifier for three-phase emulsions is selected. The selected emulsifier for three-phase emulsions can be used for both oil-in-water (O / W) emulsions and water-in-oil (W / O) emulsions.

[0014] When the triple emulsion is an O / W emulsion, a large number of triple emulsifiers are present around the oil phase, which is the internal phase, and an aqueous phase, which is the external phase, is present outside of that. That is, multiple triple emulsifiers are present at the interface between the oil phase and the aqueous phase, and the aqueous phase is the continuous phase.

[0015] In a three-phase emulsion, oil droplets constituting the oil phase are surrounded by a large number of emulsifier particles for three-phase emulsification that are smaller than the oil droplets, and are stably dispersed in the aqueous phase, which is the continuous phase.

[0016] The emulsifier for three-phase emulsification is at least one of closed vesicles (hereinafter simply referred to as closed vesicles) formed by an amphiphilic substance that spontaneously forms closed vesicles in an aqueous system and particles of polycondensation polymers having hydroxyl groups (hereinafter simply referred to as polycondensation polymer particles). Closed vesicles have the property of spontaneously forming closed vesicles in an aqueous component. Furthermore, polycondensation polymer particles include single particles of polycondensation polymers and particles formed by connecting single particles of polycondensation polymers, but do not include aggregates (having a network structure) of polycondensation polymers before they are broken down into single particles.

[0017] Particles of closed vesicles and polycondensation polymers are known as particles with the so-called three-phase emulsifying ability. Because the surfaces of the particles of closed vesicles and polycondensation polymers are hydrophilic, repulsive forces are generated between the particles of closed vesicles and polycondensation polymers.

[0018] The presence of a large number of emulsifiers for three-phase emulsification on the surface of the particulate oil phase, i.e., the surface of the oil phase is covered with a large number of emulsifiers for three-phase emulsification, generates a repulsive force between the oil phases. The repulsive force generated between the oil phases is greater than the attractive force generated between the oil phases. Therefore, aggregation of the oil phases in the aqueous phase, i.e., aggregation of the emulsified particles, is suppressed, and the dispersibility of the oil phase is maintained and improved.

[0019] Furthermore, when the triple emulsion is a W / O emulsion, a large number of emulsifiers for triple emulsification are present around the aqueous phase, which is the internal phase, and an oil phase, which is the external phase, is present outside of that. That is, multiple emulsifiers for triple emulsification are present at the interface between the oil and aqueous phases, and the oil phase is the continuous phase.

[0020] In a three-phase emulsion, water droplets constituting the aqueous phase are surrounded by a large number of emulsifier particles for three-phase emulsification that are smaller than the water droplets, and are stably dispersed in the oil phase, which is the continuous phase.

[0021] The presence of a large number of emulsifiers for three-phase emulsification on the surface of the particulate aqueous phase, i.e., the surface of the aqueous phase is covered with a large number of emulsifiers for three-phase emulsification, generates a repulsive force between the aqueous phases. The repulsive force generated between the aqueous phases is greater than the attractive force generated between the aqueous phases. Therefore, aggregation between the aqueous phases in the oil phase, i.e., aggregation between the emulsified particles, is suppressed, and the dispersibility of the aqueous phase is maintained and improved.

[0022] In the three-phase emulsification method, multiple emulsifiers for three-phase emulsification adhere to the internal oil or aqueous phase through van der Waals forces, thereby interposing themselves at the interface between the oil phase (internal phase) and the aqueous phase (external phase) or the interface between the aqueous phase (internal phase) and the oil phase (external phase), thereby enabling emulsification of the oil and aqueous phases. The three-phase emulsification mechanism is completely different from the emulsification mechanism using surfactants, which maintain an emulsified state by directing hydrophilic and hydrophobic groups toward the aqueous and oil phases, respectively, thereby lowering the interfacial tension between oil and water (see, for example, Japanese Patent Publication No. 3855203).

[0023] As mentioned above, three-phase emulsions use a three-phase emulsification technique that is completely different from the emulsification mechanism using surfactants. Therefore, three-phase emulsions can maintain a stable emulsified state even without the use of surfactants. In this way, the amount of surfactant can be significantly reduced in three-phase emulsions compared to emulsions that use surfactants, and in some cases, no surfactant is required.

[0024] The average particle size of the closed vesicles and polycondensation polymer particles is 8 nm to 800 nm before emulsification, but 8 nm to 500 nm in the triple emulsion. The average particle size of the closed vesicles and polycondensation polymer particles was measured by dynamic light scattering using a particle size distribution analyzer (FPAR, manufactured by Otsuka Electronics Co., Ltd.) and determined by Contin analysis. The preparation method for closed vesicles and polycondensation polymer particles with average particle sizes within the above range is similar to the preparation method for particles with triple emulsification ability described in Patent No. 3855203, and therefore is omitted here for brevity. Furthermore, the emulsified particles contained in the triple emulsion can be confirmed by atomic force microscopy (AFM) to confirm that the closed vesicles and polycondensation polymer particles are attached to the surface of the internal phase.

[0025] The proportion of the oil phase relative to the total mass of the triple emulsion is appropriately selected depending on the intended use of the triple emulsion. Even when the oil phase proportion is high, the emulsified state of the triple emulsion can be stably maintained. For example, the oil phase proportion may be 1.0% by mass or more, 5.0% by mass or more, 10.0% by mass or more, 20.0% by mass or more, 30.0% by mass or more, 40.0% by mass or more, 50.0% by mass or more, 60.0% by mass or more, 70.0% by mass or more, or 80.0% by mass or more. Furthermore, the oil phase proportion may be, for example, 70.0% by mass or less, 60.0% by mass or less, 50.0% by mass or less, 40.0% by mass or less, 30.0% by mass or less, 20.0% by mass or less, 10.0% by mass or less, or 5.0% by mass or less.

[0026] The proportion of the aqueous phase relative to the total mass of the three-phase emulsion is appropriately selected depending on the intended use of the three-phase emulsion. For example, the proportion of the aqueous phase may be 1.0% by mass or more, 5.0% by mass or more, 10.0% by mass or more, 20.0% by mass or more, 30.0% by mass or more, 40.0% by mass or more, 50.0% by mass or more, 60.0% by mass or more, 70.0% by mass or more, or 80.0% by mass or more. The proportion of the aqueous phase may be, for example, 70.0% by mass or less, 60.0% by mass or less, 50.0% by mass or less, 40.0% by mass or less, 30.0% by mass or less, 20.0% by mass or less, 10.0% by mass or less, or 5.0% by mass or less.

[0027] In one embodiment of the method for selecting an emulsifier for three-phase emulsification, a dispersion consisting of only an oily substance to be emulsified and an emulsifier for three-phase emulsification is prepared. The oily substance to be emulsified and the emulsifier for three-phase emulsification are stirred and dispersed for 24 hours, and then degassed for 20 minutes under reduced pressure with an aspirator to obtain a dispersion in which 2% by mass of the emulsifier for three-phase emulsification is dispersed in the oily substance. The light scattering intensity (DLS) of the dispersion thus obtained at 25°C is 1500 or greater.

[0028] The light scattering intensity of the dispersion was measured using a particle size / molecular weight measurement system (ELS-Z, manufactured by Otsuka Electronics Co., Ltd.) by filling a square glass cell (optical path length 10 mm, optical path width 10 mm) with the dispersion, setting the glass cell in the ELS-Z sample holder, fully opening the slit width (100%), and setting the temperature of the dispersion to 25°C.

[0029] Thus, in the embodiment, the method for selecting an emulsifier for three-phase emulsification is to select an emulsifier for three-phase emulsification that has a light scattering intensity of 1500 or more at 25°C when dispersed in an oily substance at 2% by mass.

[0030] When the light scattering intensity is 1500 or more, it becomes possible to stably maintain a three-phase emulsion state when the oily substance is three-phase emulsified using the emulsifier for three-phase emulsification. In other words, by using the light scattering intensity of the dispersion as an indicator, it becomes possible to determine whether a stable three-phase emulsion can be obtained, thereby making it possible to avoid situations that lead to the destabilization of three-phase emulsions over time, as has conventionally occurred.

[0031] From the viewpoint of these effects, the light scattering intensity is 1500 or more, preferably 2000 or more, and more preferably 2500 or more.

[0032] Next, the emulsifier for three-phase emulsification according to the embodiment will be described.

[0033] The emulsifier for three-phase emulsification according to the embodiment exhibits a light scattering intensity of 1500 or more at 25°C when the dispersion obtained by dispersing the emulsifier for three-phase emulsification at 2% by mass in an oily substance constituting the oil phase is obtained.

[0034] The emulsifier for three-phase emulsification according to the embodiment is preferably an emulsifier for three-phase emulsification selected by the method for selecting an emulsifier for three-phase emulsification according to the embodiment described above.

[0035] If we use as an indicator the light scattering intensity at 25°C of a dispersion obtained by dispersing a three-phase emulsifier at 2% by mass in an oily substance that constitutes the oil phase to be emulsified as being 1500 or greater, then it becomes possible to predict the emulsion stability of a three-phase emulsion based on its light scattering intensity prior to production of the three-phase emulsion, as long as there is a dispersion consisting only of an oily substance and a three-phase emulsifier. At the same time, it becomes possible to select the optimal three-phase emulsifier for any type of oil.

[0036] Next, the three-phase emulsion of the embodiment will be described.

[0037] In the three-phase emulsion according to the embodiment, the oil phase to be emulsified is emulsified using an emulsifier for three-phase emulsification, which exhibits a light scattering intensity of 1500 or more at 25°C when the dispersion obtained by dispersing the emulsifier at 2% by mass in the oily substance that constitutes the oil phase is obtained.

[0038] The emulsifier for three-phase emulsification contained in the three-phase emulsion is preferably an emulsifier for three-phase emulsification selected by the method for selecting an emulsifier for three-phase emulsification of the above embodiment, or an emulsifier for three-phase emulsification of the above embodiment.

[0039] A triple-emulsified emulsion contains an emulsifier for triple emulsification, an oil phase, and an aqueous phase. The oil phase is derived from the oily substance, and the aqueous phase is derived from an aqueous substance. The aqueous substance is an aqueous component that is immiscible with the oil phase. The aqueous phase is, for example, water.

[0040] In a three-phase emulsion, if a dispersion obtained by dispersing 2% by mass of an emulsifier for three-phase emulsification in an oily substance to be emulsified exhibits a light scattering intensity of 1500 or more at 25°C, it will be possible to stably maintain the three-phase emulsified state when the oily substance is three-phase emulsified using the emulsifier for three-phase emulsification. In other words, by using the light scattering intensity of the dispersion as an indicator, it is possible to determine whether a stable three-phase emulsion can be obtained, thereby making it possible to avoid situations that would previously lead to the destabilization of three-phase emulsions over time.

[0041] Furthermore, the three-phase emulsion may contain various substances in addition to the emulsifier for three-phase emulsification, oily substance, and aqueous substance, as long as the above-described effects of this embodiment are not reduced.

[0042] Next, the three-phase emulsification method of the embodiment will be described.

[0043] The three-phase emulsification method of the embodiment uses an emulsifier for three-phase emulsification, which when dispersed at 2 mass % in an oily substance to be three-phase emulsified, produces a dispersion having a light scattering intensity of 1500 or more at 25°C.

[0044] The three-phase emulsification method uses an emulsifier for three-phase emulsification selected by the method for selecting an emulsifier for three-phase emulsification of the above embodiment, an emulsifier for three-phase emulsification of the above embodiment, or an emulsifier for three-phase emulsification contained in the three-phase emulsion of the above embodiment.

[0045] In the three-phase emulsification method, an emulsifier for three-phase emulsification is used to emulsify an oily substance and an aqueous substance, thereby producing a three-phase emulsion. The resulting three-phase emulsion contains the emulsifier for three-phase emulsification, an oil phase derived from the oily substance, and an aqueous phase derived from the aqueous substance.

[0046] Specifically, the three-phase emulsification method includes a mixing step and an emulsification step.

[0047] When the triple emulsion is an O / W emulsion, the mixing step involves mixing at least one of closed vesicles formed by an amphiphilic substance that spontaneously forms closed vesicles in an aqueous system and particles of a polycondensation polymer having hydroxyl groups with an aqueous substance such as water to obtain a mixed solution in which multiple emulsifiers for triple emulsion (at least one of multiple closed vesicles and multiple polycondensation polymer particles) are dispersed in the aqueous substance.

[0048] For example, when closed vesicles formed by an amphiphilic substance that spontaneously forms closed vesicles in an aqueous system are used, a predetermined amount of amphiphilic substance is added to the aqueous substance while stirring the aqueous substance with a stirrer or the like in the mixing step, thereby forming multiple closed vesicles, and the multiple closed vesicles are mixed with the aqueous substance. For example, the stirring speed of the aqueous substance is 1000 rpm or more. Furthermore, when particles of polycondensation polymers having hydroxyl groups are used, the multiple polycondensation polymers are mixed with the aqueous substance by adding multiple particles of the polycondensation polymer to the aqueous substance while stirring the aqueous substance with a stirrer or the like in the mixing step.

[0049] Furthermore, when closed vesicles and polycondensation polymer particles are used in combination, a mixed solution may be prepared by mixing a solution in which closed vesicles are dispersed with a solution in which polycondensation polymer particles are dispersed, or a mixed solution may be prepared by adding an amphiphilic substance and polycondensation polymer particles to an aqueous substance.

[0050] In order to maintain the dispersibility of the emulsifier for three-phase emulsification in the mixed solution, the mixed solution may be continuously stirred at a speed lower than that in the mixing step until the emulsification step is carried out.

[0051] In the emulsification step carried out after the mixing step, an oily substance is added to the mixed solution obtained in the mixing step while stirring the mixed solution with a stirrer or the like, thereby forming emulsified particles, and a three-phase emulsion containing a plurality of emulsified particles dispersed in the aqueous phase is obtained.

[0052] When the triple emulsion is a W / O type emulsion, the mixing step is carried out in the same manner as in the case of an O / W type emulsion to obtain a mixed solution.

[0053] In the emulsification step carried out after the mixing step, the mixed solution obtained in the mixing step is added to the oily substance while stirring the oily substance with a stirrer or the like, thereby forming emulsified particles, and a three-phase emulsion containing a plurality of emulsified particles dispersed in the oil phase is obtained.

[0054] In the three-phase emulsification method, if the light scattering intensity at 25°C of the dispersion obtained by dispersing 2% by mass of a three-phase emulsifier in the oily substance to be emulsified is used as an indicator, then as long as there is a dispersion consisting only of an oily substance and a three-phase emulsifier, it becomes possible to predict the emulsion stability of the three-phase emulsion based on its light scattering intensity before producing the three-phase emulsion. At the same time, it becomes possible to select the optimal three-phase emulsifier for any type of oil.

[0055] In the three-phase emulsification method, various substances may be mixed in addition to the emulsifier for three-phase emulsification, oily substance, and aqueous substance, as long as the above-described effects of this embodiment are not reduced.

[0056] According to the embodiment described above, by using the light scattering intensity of a dispersion obtained by dispersing an emulsifier for three-phase emulsification in an oily substance to be three-phase emulsified as an indicator, it is possible to determine whether a stable three-phase emulsion can be obtained, thereby making it possible to avoid situations that have conventionally occurred, in which three-phase emulsions become unstable over time.

[0057] Although the embodiments have been described above, the present invention is not limited to the above embodiments, but includes all aspects encompassed by the concept and scope of the claims of the present disclosure, and can be modified in various ways within the scope of the present disclosure. [Example]

[0058] Next, examples and comparative examples will be described, but the present invention is not limited to these examples.

[0059] (Examples 1 to 15, 19 to 20, 24 to 26 and Comparative Examples 1 to 10) The oily substances and three-phase emulsifiers shown in Tables 1 and 2 were stirred and dispersed using a stirrer at a stirring speed of 700 rpm for 24 hours, and then degassed using an aspirator at reduced pressure for 20 minutes to prepare the dispersions shown in Tables 1 and 2.

[0060] Next, using a particle size / molecular weight measurement system (ELS-Z, manufactured by Otsuka Electronics Co., Ltd.), the resulting dispersion was filled into a square glass cell (light path length 10 mm, light path width 10 mm), the glass cell was set in the ELS-Z sample holder, and the light scattering intensity was measured 50 times under the conditions of a dispersion temperature of 25°C and a slit width fully open (100%). The average value obtained by averaging the multiple measurements was calculated and used as the light scattering intensity (light quantity) of the dispersion. The results are shown in Tables 1 and 2.

[0061] In addition to the emulsion stability of the three-phase emulsion based on the light scattering intensity of the dispersion, we also confirmed the emulsion stability by actually preparing a three-phase emulsion. Specifically, a three-phase emulsifier shown in Tables 1 and 2 was mixed with water to prepare a 2% by mass mixed solution. Next, 50 g of the oily substance shown in Tables 1 and 2 was gradually added to 50 g of the resulting mixed solution while stirring (stirring speed: 8000 rpm, stirring time: 10 minutes). Thus, a three-phase emulsion was prepared. Seven days after preparation, the three-phase emulsion was visually observed to determine its emulsion stability. The emulsion stability was ranked as pass (○) when no separation between the oil and water phases was observed, and fail (×) when separation between the oil and water phases was observed. The results are shown in Tables 1 and 2.

[0062] (Examples 16 to 18 and Examples 21 to 23) The light scattering intensity of the dispersion was measured in the same manner as in Example 1, except that the oily substance and the emulsifier for three-phase emulsification shown in Tables 1 and 2 were heated and stirred using a stirrer at a heating temperature of 85°C and a stirring speed of 800 rpm for 20 minutes, and then the mixture was allowed to cool without heating while stirring at a stirring speed of 800 rpm for 24 hours, and then degassed under reduced pressure with an aspirator for 20 minutes to prepare the dispersion shown in Tables 1 and 2. Furthermore, a three-phase emulsion was prepared in the same manner as in Example 1, and the three-phase emulsion was visually observed.

[0063] The specific substance names of the oily substances listed in Tables 1 and 2 are as follows: MCT: Medium Chain Triglycerides AS-300: Alternative to CFCs (AMOLEA (registered trademark) AS-300)

[0064] The specific substance names of the emulsions for three-phase emulsification listed in Tables 1 and 2 are as follows: HCO-10, HCO-20, HCO-40, HCO-100, CW-200: Polyoxyethylene hydrogenated castor oil 2S10G: Decaglyceryl distearate 1S5G: Pentaglyceryl monostearate S-570, S-970, S-1670: Sucrose fatty acid esters 1isoS2G: Diglyceryl monoisostearate

[0065] [Table 1]

[0066] [Table 2]

[0067] As shown in Tables 1 and 2, three-phase emulsions were actually prepared, and after a predetermined time had passed, the three-phase emulsions were visually inspected. In the above Examples, where the light scattering intensity of the dispersion consisting only of the oily substance to be three-phase emulsified and the emulsifier for three-phase emulsification was 1500 or greater, the emulsion stability of the three-phase emulsions was good. On the other hand, in the above Comparative Examples, where the light scattering intensity of the dispersion was less than 1500, the emulsion stability of the three-phase emulsions was poor. In Example 1, the concentration of the emulsifier for three-phase emulsification in the dispersion was 1% by mass, and since the light scattering intensity of the 1% by mass dispersion was 1500 or greater, it is technically clear that the light scattering intensity of a dispersion containing a 2% by mass concentration of the emulsifier for three-phase emulsification is 1500 or greater.

Claims

1. A method for selecting an emulsifier for three-phase emulsification, which selects an emulsifier for three-phase emulsification that has a light scattering intensity (DLS) of 1500 or more at 25°C when dispersed at 2% by mass in an oily substance to be three-phase emulsified.

2. An emulsifier for three-phase emulsification of a three-phase emulsion, An emulsifier for three-phase emulsification, wherein the dispersion obtained by dispersing the emulsifier for three-phase emulsification in an oily substance constituting the oil phase at 2% by mass exhibits a light scattering intensity of 1500 or more at 25°C.

3. The emulsifier for three-phase emulsion according to claim 2, which is at least one of closed vesicles formed by an amphiphilic substance that spontaneously forms closed vesicles in an aqueous system and particles of a polycondensation polymer having hydroxyl groups.

4. A three-phase emulsion using an emulsifier for three-phase emulsification, which when dispersed at 2% by mass in an oily substance to be emulsified exhibits a light scattering intensity of 1500 or more at 25°C.

5. A three-phase emulsification method using an emulsifier for three-phase emulsification, which has a light scattering intensity of 1500 or more at 25°C when dispersed at 2% by mass in an oily substance to be three-phase emulsified.

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