Selection method for emulsifiers for three-phase emulsification, emulsifiers for three-phase emulsification, three-phase emulsification emulsions, and three-phase emulsification methods.

Abstract

This invention provides a method for selecting a three-phase emulsifier that has stable emulsifying ability for the oil type to be emulsified, a three-phase emulsifier, a three-phase emulsion using the emulsifier, and a three-phase emulsification method. [Solution] The method for selecting an emulsifier for three-phase emulsification is to select an emulsifier whose light scattering intensity at 25°C is 1500 or more when dispersed at a concentration of 2% by mass in an oily substance to be emulsified in three phases.

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 emulsified emulsion, and a three-phase emulsification method.

Background Art

[0002] The three-phase emulsification method is a method of emulsification by attaching an emulsifier for three-phase emulsification to the surface of the internal phase by van der Waals forces, which is different from the surfactant-type emulsification method by reducing the surface tension using an amphiphilic surfactant having both hydrophilic and hydrophobic properties.

[0003] For example, Patent Document 1 describes a water-in-oil (W / O) type emulsion containing an inverse vesicle formed from a sucrose fatty acid ester as an emulsifier, wherein the emulsion contains a nonionic surfactant other than the sucrose fatty acid ester. In Patent Document 1, in the evaluation of the emulsification stability of a water-in-oil (W / O) type emulsion obtained by a three-phase emulsification method using an inverse vesicle formed from a sucrose fatty acid ester as an emulsifier, the emulsification state of the emulsion after standing for a predetermined time is visually observed.

[0004] However, not limited to the disclosed technology of Patent Document 1, the emulsification stability has to rely solely on the confirmation after the production of the three-phase emulsified emulsion. Generally, it is assumed that the emulsifier used for three-phase emulsification is a hydrophilic nanoparticle that is insoluble in both water and oil, but depending on the oil type, there are also substances that have the property of dissolving these hydrophilic nanoparticles over time even though they appear to be in a stable emulsified state at the beginning of emulsification. If the hydrophilic nanoparticles that should have been present at the oil-water interface dissolve, naturally the emulsified state becomes unstable, and ultimately the emulsified state itself cannot be maintained. The present invention proposes, using the physical properties that an emulsifier to be used for a specific oil type should have in order to maintain stable emulsification as an index, before performing three-phase emulsification.

Prior Art Documents

Patent Documents

[0005] [Patent Document 1] Japanese Patent Publication No. 2012-16668 [Overview of the Initiative] [Problems that the invention aims to solve]

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

[0007] [1] A method for selecting a three-phase emulsifier, wherein the light scattering intensity (DLS) at 25°C of the dispersion obtained by dispersing 2% by mass in an oily substance to be three-phase emulsified is 1500 or more. [2] A three-phase emulsifier for a three-phase emulsion, wherein the dispersion obtained by dispersing the three-phase emulsifier 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 three-phase emulsifier according to [2] above, wherein the emulsifier for three-phase emulsification is at least one of a closed vesicle formed by an amphiphilic substance that spontaneously forms a closed vesicle in an aqueous system and particles of a polycondensation polymer having hydroxyl groups. [4] A three-phase emulsified emulsion using a three-phase emulsifier obtained by dispersing 2% by mass in an oily substance to be emulsified in three phases, the dispersion exhibiting a light scattering intensity of 1500 or more at 25°C. [5] A three-phase emulsification method using a three-phase emulsifier in which a dispersion obtained by dispersing 2% by mass in an oily substance to be emulsified in 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 emulsified emulsion using the emulsifier, and a three-phase emulsification method, which enable extremely efficient and reliable identification and selection of an emulsifier that provides stable emulsification for any oil to be emulsified. [Modes for carrying out the invention]

[0009] The following will provide a detailed explanation based on the embodiments.

[0010] As a result of diligent research, the inventors of this invention have discovered that the light scattering intensity at 25°C of a dispersion obtained by dispersing a three-phase emulsifying emulsifier in an oily substance to be emulsified in three phases is within a predetermined range, which serves as an indicator for determining the emulsification stability of the three-phase emulsion. Based on this finding, the inventors have completed the present invention.

[0011] First, we will explain the method for selecting the emulsifier for three-phase emulsification in the embodiment.

[0012] The method for selecting the emulsifier for three-phase emulsification in this embodiment is to select a three-phase emulsifier in which the light scattering intensity at 25°C of the dispersion obtained by dispersing 2% by mass in an oily substance to be emulsified in three phases is 1500 or higher.

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

[0014] In the case of an O / W type emulsion, numerous three-phase emulsifiers exist around the oil phase (internal phase), and the aqueous phase (external phase) exists outside of that. In other words, multiple three-phase emulsifiers are interposed at the interface between the oil phase and the aqueous phase, and the aqueous phase is a continuous phase.

[0015] In a three-phase emulsion, oil droplets constituting the oil phase are surrounded by numerous three-phase emulsifier particles smaller than the oil droplets and are stably dispersed in the continuous aqueous phase.

[0016] The emulsifier for three-phase emulsification is at least one of two components: an amphiphilic substance that spontaneously forms closed vesicles in an aqueous system (hereinafter also simply referred to as a closed vesicle), and particles of a polycondensed polymer having hydroxyl groups (hereinafter also simply referred to as polycondensed polymer particles). The closed vesicles have the property of spontaneously forming closed vesicles in the aqueous component. Furthermore, the polycondensed polymer particles include single polycondensed polymer particles and linked single polycondensed polymer particles, but do not include aggregates of polycondensed polymer (which have a network structure) before they are separated into single particles.

[0017] Closed vesicles and polycondensed polymer particles are known as particles with so-called three-phase emulsifying ability. Because the surfaces of closed vesicles and polycondensed polymer particles are hydrophilic, these particles repel each other.

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

[0019] Furthermore, in the case of a three-phase emulsion that is a W / O type emulsion, numerous three-phase emulsifiers exist around the aqueous phase, which is the inner phase, and the oil phase, which is the outer phase, exists further outside of that. In other words, multiple three-phase emulsifiers are interposed at the interface between the oil phase and the aqueous phase, and the oil phase is a continuous phase.

[0020] In a three-phase emulsion, water droplets constituting the aqueous phase are surrounded by numerous three-phase emulsifier particles smaller than the water droplets and are stably dispersed in the continuous oil phase.

[0021] A large number of emulsifiers for three-phase emulsification exist on the surface of the particulate aqueous phase. That is, by covering the surface of the aqueous phase with a large number of emulsifiers for three-phase emulsification, a repulsive force is generated between the aqueous phases. The repulsive force generated between the aqueous phases is greater than the attractive force generated between the aqueous phases. Therefore, the aggregation of the aqueous phases in the oil phase, that is, the aggregation of the emulsion particles, is suppressed, and the dispersibility of the aqueous phase is maintained and improved.

[0022] The three-phase emulsification method is such that a plurality of emulsifiers for three-phase emulsification adhere to the oil phase or aqueous phase as the inner phase by van der Waals force, and are interposed at the interface between the oil phase (inner phase) and the aqueous phase (outer phase) or at the interface between the aqueous phase (inner phase) and the oil phase (outer phase), enabling the emulsification of the oil phase and the aqueous phase. The emulsification mechanism by a surfactant that maintains the emulsified state by directing the hydrophilic group and the hydrophobic group toward the aqueous phase and the oil phase respectively and reducing the oil-water interfacial tension is completely different from the three-phase emulsification mechanism (see, for example, Japanese Patent Publication No. 3855203).

[0023] As described above, the three-phase emulsion applies a three-phase emulsification technique that is completely different from the emulsification mechanism by a surfactant. Therefore, the three-phase emulsion can maintain a stable emulsified state even without containing a surfactant. Thus, in the three-phase emulsion, compared with the emulsion using a surfactant, the amount of the surfactant can be significantly reduced, and in some cases, no surfactant is contained.

[0024] The average particle diameter of the closed vesicles and the polycondensed polymer particles is 8 nm or more and 800 nm or less before forming the emulsion particles, but is 8 nm or more and 500 nm or less in the triple-phase emulsion. The average particle diameter of the closed vesicles and the polycondensed polymer particles is a value obtained by the dynamic light scattering method using a particle size distribution measuring device FPAR (manufactured by Otsuka Electronics Co., Ltd.) and determined by Contin analysis. The method for preparing the closed vesicles and the polycondensed polymer particles having an average particle diameter within the above range is the same as the method for preparing particles having a triple-phase emulsifying ability, such as Patent No. 3855203, and is therefore omitted here for convenience. Also, regarding the emulsion particles contained in the triple-phase emulsion, atomic force microscopy (AFM) observation can be performed to confirm that the closed vesicles and the polycondensed polymer particles are attached to the surface of the inner phase.

[0025] The content ratio of the oil phase with respect to the total mass of the triple-phase emulsion is appropriately selected according to the use of the triple-phase emulsion and the like. Even if the content ratio of the oil phase is high, the emulsified state of the triple-phase emulsion can be stably maintained. For example, the content ratio of the above oil 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, 80.0% by mass or more. Also, the content ratio of the above oil 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, 5.0% by mass or less.

[0026] The proportion of the aqueous phase to the total mass of the three-phase emulsion is appropriately selected depending on the application 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. Alternatively, 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 the method for selecting the three-phase emulsifier of the embodiment, a dispersion is prepared consisting only of the oily substance to be emulsified and the three-phase emulsifier. The oily substance to be emulsified and the three-phase emulsifier are stirred and dispersed for 24 hours, and then degassed for 20 minutes under reduced pressure in an aspirator to obtain a dispersion in which 2% by mass of the three-phase emulsifier is dispersed in the oily substance. The light scattering intensity (DLS) of the dispersion thus obtained at 25°C is 1500 or higher.

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

[0029] Thus, the method for selecting the three-phase emulsifier in this embodiment involves selecting a three-phase emulsifier whose dispersion obtained by dispersing it in an oily substance at a concentration of 2% by mass has a light scattering intensity of 1500 or more at 25°C.

[0030] When the above light scattering intensity is 1500 or higher, it becomes possible to stably maintain the three-phase emulsion state when the oily substance is emulsified in three phases using a three-phase emulsifying emulsifier. In other words, by using the light scattering intensity of the dispersion as an indicator, it is possible to determine whether or not a stable three-phase emulsion can be obtained, thus avoiding situations that cause the three-phase emulsion to become unstable over time, as has been the case in the past.

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

[0032] Next, the three-phase emulsifier of the embodiment will be described.

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

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

[0035] By using the light scattering intensity of a dispersion obtained by dispersing a three-phase emulsifier at 2% by mass in an oily substance constituting the oil phase to be emulsified as an indicator, it becomes possible to predict the emulsification stability of a three-phase emulsion based on its light scattering intensity, even before the three-phase emulsion is manufactured, as long as a dispersion consisting only of the oily substance and the three-phase emulsifier is available. At the same time, it becomes possible to select the optimal three-phase emulsifier for any given oil type.

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

[0037] In the embodiment, the three-phase emulsified emulsion is in a state in which the oil phase, which is the target of three-phase emulsification, is emulsified with a three-phase emulsifying emulsifier that exhibits a light scattering intensity of 1500 or more at 25°C when the dispersion is obtained by dispersing 2% by mass in the oily substance constituting the oil phase.

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

[0039] A three-phase emulsion contains a three-phase emulsifier, an oil phase, and an aqueous phase. The oil phase is derived from the oily substance described above, and the aqueous phase is derived from an aqueous substance. The aqueous substance is an aqueous component and does not mix with the oil phase. The aqueous phase is, for example, water.

[0040] In a three-phase emulsion, if the light scattering intensity of a dispersion obtained by dispersing 2% by mass of a three-phase emulsifying emulsifier in an oily substance to be emulsified is 1500 or higher at 25°C, then it becomes possible to stably maintain the three-phase emulsion state when the oily substance is emulsified in three phases using the three-phase emulsifying emulsifier. In other words, by using the light scattering intensity of the dispersion as an indicator, it is possible to determine whether or not a stable three-phase emulsion can be obtained, thus avoiding situations that lead to the destabilization of three-phase emulsions over time, as has been the case with conventional methods.

[0041] Furthermore, the three-phase emulsion may contain various substances in addition to the three-phase emulsifier, oily substance, and aqueous substance, as long as it does not reduce the effects of this embodiment.

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

[0043] The three-phase emulsification method of this embodiment uses a three-phase emulsifier in which the light scattering intensity at 25°C of the dispersion obtained by dispersing 2% by mass in an oily substance to be emulsified in three phases is 1500 or more.

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

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

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

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

[0048] For example, when using closed vesicles formed by an amphiphilic substance that spontaneously forms closed vesicles in an aqueous system, in the mixing step, multiple closed vesicles are formed by adding a predetermined amount of the amphiphilic substance to the aqueous substance while stirring the aqueous substance with a stirrer, 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. Also, when using particles of polycondensation polymer having hydroxyl groups, in the mixing step, multiple polycondensation polymer particles are added to the aqueous substance while stirring the aqueous substance with a stirrer, and the multiple polycondensation polymers are mixed with the aqueous substance.

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

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

[0051] In the emulsification step, which follows the mixing step, an oily substance is added to the mixed solution obtained in the mixing step while stirring it with a stirrer or the like. This forms emulsion particles, resulting in a three-phase emulsion containing multiple emulsion particles dispersed in the aqueous phase.

[0052] Furthermore, if the three-phase emulsion is a W / O type emulsion, the mixed solution is obtained in the mixing step in the same manner as when it is an O / W type emulsion.

[0053] In the emulsification step, which follows the mixing step, the mixed solution obtained in the mixing step is added to the oily substance while stirring it with a stirrer or the like, thereby forming emulsion particles and obtaining a three-phase emulsion containing multiple emulsion particles dispersed in the oil phase.

[0054] In a three-phase emulsification method, if the light scattering intensity of a dispersion obtained by dispersing 2% by mass of a three-phase emulsifier in an oily substance to be emulsified is 1500 or higher at 25°C, then it becomes possible to predict the emulsification stability of a three-phase emulsion based on its light scattering intensity, even before the emulsion is manufactured, as long as a dispersion consisting only of the oily substance and the three-phase emulsifier is available. At the same time, it becomes possible to select the optimal three-phase emulsifier for any given type of oil.

[0055] Furthermore, in the three-phase emulsification method, various substances may be mixed in addition to the three-phase emulsifier, oily substance, and aqueous substance, as long as they do not reduce the effects of this embodiment.

[0056] According to the embodiments described above, by using the light scattering intensity of a dispersion obtained by dispersing a three-phase emulsifying emulsifier in an oily substance to be three-phase emulsified as an indicator, it is possible to determine whether or not a stable three-phase emulsion can be obtained, thereby avoiding situations that cause the three-phase emulsion to become unstable over time, as has been the case in the past.

[0057] Although embodiments have been described above, the present invention is not limited to the embodiments described above, and includes all aspects included in the concepts and claims of this disclosure, and can be modified in various ways within the scope of this disclosure. [Examples]

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

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

[0060] Next, using a particle size and molecular weight measurement system (ELS-Z, manufactured by Otsuka Electronics Co., Ltd.), the obtained dispersion was filled into a rectangular glass cell (optical path length 10 mm, optical path width 10 mm). The glass cell was then set in the ELS-Z sample holder, and the light scattering intensity was measured 50 times under conditions of a dispersion temperature of 25°C and a fully open slit width (100%). The average value obtained by averaging the multiple measurements was 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 emulsification stability of the three-phase emulsion based on the light scattering intensity of the dispersion, we also confirmed the emulsification stability by actually preparing a three-phase emulsion. Specifically, we prepared a 2% by mass mixed solution by mixing the three-phase emulsifiers shown in Tables 1-2 with water. Then, while stirring 50g of the resulting mixed solution, we successively added 50g of the oily substances shown in Tables 1-2 (stirring speed: 8000 rpm, stirring time: 10 minutes). In this way, we prepared a three-phase emulsion. Then, we visually observed the three-phase emulsion 7 days after preparation to determine its emulsification stability. For emulsification stability, a pass (○) was given if separation of the oil phase and aqueous phase was not observed, and a fail (×) was given if separation of the oil phase and aqueous phase was observed. The results are shown in Tables 1-2.

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

[0063] The specific names of the oily substances listed in Tables 1 and 2 are as follows: MCT: Medium-chain triglyceride • AS-300: Alternative refrigerant (AMOLEA® registered trademark AS-300)

[0064] Furthermore, the specific substance names of the three-phase emulsifiers listed in Tables 1-2 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, when a three-phase emulsion was actually prepared and visually inspected after a predetermined time, the emulsification stability of the three-phase emulsion was good in the above example where the light scattering intensity of the dispersion consisting only of the oily substance to be emulsified in three phases and the emulsifier for three-phase emulsification was 1500 or higher. On the other hand, in the above comparative example where the light scattering intensity of the dispersion was less than 1500, the emulsification stability of the three-phase emulsion was poor. In Example 1, the concentration of the emulsifier for three-phase emulsification in the dispersion was 1% by mass, but since the light scattering intensity of the 1% by mass dispersion was 1500 or higher, it is technically clear that the light scattering intensity of the dispersion with a concentration of 2% by mass of the emulsifier for three-phase emulsification is 1500 or higher.

Claims

1. A three-phase emulsifier for three-phase emulsions, The three-phase emulsifier is composed of at least one of a closed vesicle formed by an amphiphilic substance that spontaneously forms a closed vesicle in an aqueous system, and particles of a polycondensed polymer having hydroxyl groups. A three-phase emulsifier obtained by dispersing 2% by mass of the three-phase emulsifier in an oily substance constituting the oil phase exhibits a light scattering intensity of 1500 or more at 25°C (excluding cases where the oily substance is a medium-chain fatty acid triglyceride and the three-phase emulsifier is a derivative of polyoxyethylene hydrogenated castor oil (HCO-20), and cases where the oily substance is liquid paraffin and the three-phase emulsifier is a derivative of polyoxyethylene hydrogenated castor oil (HCO-20)).

2. A three-phase emulsified emulsion is obtained by using a three-phase emulsifier that exhibits a light scattering intensity of 1500 or more at 25°C when dispersed at 2% by mass in an oily substance to be emulsified in three phases (excluding cases where the oily substance is a medium-chain fatty acid triglyceride and the three-phase emulsifier is a derivative of polyoxyethylene hydrogenated castor oil (HCO-20), and cases where the oily substance is liquid paraffin and the three-phase emulsifier is a derivative of polyoxyethylene hydrogenated castor oil (HCO-20)).

3. A three-phase emulsion (excluding cases where the oily substance is a medium-chain fatty acid triglyceride and the three-phase emulsion is a derivative of polyoxyethylene hydrogenated castor oil (HCO-20), and cases where the oily substance is liquid paraffin and the three-phase emulsion is a derivative of polyoxyethylene hydrogenated castor oil (HCO-20)) that does not separate the oil phase and the aqueous phase even after at least 7 days from the time of preparation.

Images