Core-shell multiple emulsion and method for preparing same

Abstract

The present invention relates to a core-shell multiple emulsion and a method for preparing same, and provides a stable core-shell multiple emulsion comprising: a first oil phase portion forming a core; an aqueous phase portion forming a shell; and a second oil phase portion forming an outer continuous phase, wherein the aqueous phase portion includes a thickener, and the first oil phase portion and the second oil phase portion include oil, polyol, and a surfactant. This method for preparing the core-shell multiple emulsion can be performed in a bi-continuous phase, thus preventing phase inversion, and enables oil droplets that have not undergone phase inversion to form the core of the core-shell multiple emulsion, thus making it possible to stably and practically prepare the core-shell multiple emulsion.

Description

Core-shell multiple emulsion and its preparation method

[0001] The present invention relates to a core-shell multiple emulsion and a method for producing the same, and more particularly, to a core-shell structured multiple emulsion having a high internal phase occupancy rate and a method for producing the core-shell multiple emulsion capable of practical mass production thereof.

[0002] A multiple emulsion is an emulsion particle in which emulsion particles are doubly or more dispersed within other particles. Because multiple emulsions coexist within a single particle, they are thermodynamically very complex and unstable systems. However, because the inner phase of a multiple emulsion is not directly exposed to external factors such as ultraviolet rays and other reactive substances, it has the advantage of effectively preserving and delivering active ingredients. Therefore, these multiple emulsions are widely used in various industries, including pharmaceuticals, cosmetics, and food.

[0003] Multiple emulsions are typically formed in the form of relatively small emulsions dispersed within the inner phase of a larger emulsion. This general form of multiple emulsion is most commonly formed using a two-step formation method. For example, to form an oil-in-water-in-oil (O / W / O) emulsion, a water-in-oil emulsion is formed in the first step, and then the water-in-oil emulsion is added to the oil phase and emulsified in the second step. However, if this conventional method is adopted, a hydrophilic emulsifier must be used in the first step and a lipophilic emulsifier in the second step. This leads to i) interference between surfactant components and ii) increased specific surface area due to the large dispersion of relatively small emulsions within the inner phase of the larger emulsion, making it thermodynamically more unstable. Therefore, multiple emulsions obtained by this method have a limit to the volume of emulsion (inner phase occupancy ratio) that can be stably contained within the inner phase.

[0004] Core-shell multiple emulsions, whose inner phase consists of a single core, have a lower specific surface area than conventional multiple emulsions, making them thermodynamically more stable and geometrically capable of achieving a high inner phase occupancy rate. However, despite these advantages of core-shell multiple emulsions, no composition or method exists for their effective manufacture, necessitating further development.

[0005] Accordingly, the inventor of the present invention has completed the present invention by confirming that a multiple emulsion having a core-shell structure in which oil droplets become the first oil phase, the water phase continuous phase becomes the shell, and the oil phase becomes the first oil phase can be produced by forming a bi-continuous phase in which the water phase and the oil phase are united while maintaining a part of the oil phase in a liquid droplet state using a reverse emulsification method in which an oil phase is added to an aqueous phase, and then adding more oil phase can be produced.

[0006] The purpose of the present invention is to provide a core-shell multiple emulsion and a method for producing the core-shell multiple emulsion that can stably and practically produce the same.

[0007] The technical problems of the present invention are not limited to the technical problems mentioned above, and other technical problems not mentioned will be clearly understood by those skilled in the art from the description below.

[0008] According to an embodiment of the present invention, a core-shell multiple emulsion is provided, which comprises a first oil phase forming a core, a water phase forming a shell, and a second oil phase forming a continuous external phase, wherein the water phase comprises a thickener, and the first oil phase comprises oil, polyol, and surfactant.

[0009] According to an embodiment of the present invention, a method for producing a core-shell multiple emulsion is provided, including: (S1) a step of introducing an oil phase into a water phase to produce a mixture of an aqueous phase and an oil phase including oil droplets; (S2) a step of further introducing the oil phase into the mixture of the two continuous phases produced in step S1 to form a core-shell multiple emulsion comprising a first oil phase forming a core, an aqueous phase forming a shell, and a second oil phase forming a second continuous phase.

[0010] According to an embodiment of the present invention, a cosmetic composition comprising the core-shell multiple emulsion of the present invention is provided.

[0011] The core-shell multiple emulsion of the present invention comprises a single core with excellent internal stability. Therefore, the high internal phase occupancy rate enables the particle to contain a high content of active ingredients.

[0012] In addition, a core-shell multiple emulsion can be prepared using one type of surfactant, thereby forming a more stable multiple emulsion system.

[0013] The method for producing a core-shell multiple emulsion according to the present invention can be applied to a mass production process.

[0014] In addition, the above manufacturing method can control the radius of the core-shell multiple emulsion or the shell thickness of the multiple emulsifying particles, so that a core-shell multiple emulsion of a desired size can be manufactured.

[0015] In order to more fully understand the drawings cited in the detailed description of the present invention, a brief description of each drawing is provided.

[0016] Figure 1 is a schematic diagram showing the form of a core-shell multiple emulsion of the present invention.

[0017] Figure 2a is a schematic diagram showing that when a thickener is included in the water phase, the oil phase does not unite and a first oil phase is formed, thereby forming a CSME.

[0018] Figure 2b is a schematic diagram showing the mechanism by which general reverse emulsification occurs without including a thickener in the water phase.

[0019] Figure 3 is a graph showing the phase formed according to the volume fraction of the oil phase during the core-shell multiple emulsion manufacturing process when the oil phase is added to the water phase, depending on whether a thickener is included in the water phase.

[0020] Figure 4 is a schematic diagram showing that when the oil phase is injected into the water phase, the surfactant that emulsifies the polyol or forms reverse micelles moves to the interface between the oil phase and the water phase, and the polyol is released from the oil phase to the water phase.

[0021] Figure 5 is a schematic diagram showing the change in the volume fraction of the oil phase during the core-shell multiple emulsion manufacturing process. When polyol is included in the oil phase, the increase in the ratio of the oil phase is slower than the introduction of the oil phase, and the overall ratio of the oil phase decreases due to the release of the polyol even when cooling without the introduction of additional materials.

[0022] Figure 6 is a graph showing the change in shell thickness of a core-shell multiple emulsion according to the content of surfactant.

[0023] Figure 7 is a schematic diagram showing that a uniform UV blocking effect can be exhibited when a UV blocking agent component is applied to the core-shell multiple emulsion of the present invention.

[0024] Figure 8 is a schematic diagram showing the mechanism by which CSME is formed through a bi-continuous phase.

[0025] Figure 9 is a graph showing the change in the radius of a core-shell multiple emulsion according to the stirring speed in steps S1 and S2 of the method for producing a core-shell multiple emulsion of the present invention.

[0026] Figure 10 is a photograph of the core-shell multiple emulsion of Example 1 observed under a microscope.

[0027] According to an embodiment of the present invention, a core-shell multiple emulsion is provided, which comprises a first oil phase forming a core, a water phase forming a shell, and a second oil phase forming a continuous external phase, wherein the water phase comprises a thickener, and the first oil phase comprises oil, polyol, and surfactant.

[0028] Additionally, the thickener may be characterized as being a water-soluble thickener.

[0029] Additionally, the oil may be selected from silicone-based oil, hydrocarbon-based oil, and ester-based oil.

[0030] In addition, the polyol may include at least one selected from the group consisting of monoalcohols and polyalcohols having less than 7 carbon atoms.

[0031] In addition, the surfactant may include at least one type that is compatible with the oil.

[0032] According to an embodiment of the present invention, a method for producing a core-shell multiple emulsion is provided, including: (S1) a step of introducing an oil phase into a water phase to produce a mixture of an aqueous phase and an oil phase including oil droplets; (S2) a step of further introducing the oil phase into the mixture of the two continuous phases produced in step S1 to form a core-shell multiple emulsion comprising a first oil phase forming a core, an aqueous phase forming a shell, and a second oil phase forming a second continuous phase.

[0033] In addition, the above manufacturing method may further include a step of cooling the core-shell multiple emulsion manufactured in step S2 (S3).

[0034] Additionally, the water-soluble thickener of the above step S1 may include a water-soluble thickener.

[0035] Additionally, the oil phase of the above S1 step may include oil, polyol, and surfactant.

[0036] Additionally, the above S1 step can be performed with stirring.

[0037] Additionally, the above S2 step can be performed with stirring.

[0038] Additionally, the above S3 step can be performed with stirring.

[0039] According to an embodiment of the present invention, a cosmetic composition comprising the core-shell multiple emulsion of the present invention is provided.

[0040] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the present invention pertains. In general, the nomenclature used herein is well known and commonly used in the art. In addition, when describing embodiments of the present invention, if a detailed description of a related known structure or function is judged to hinder the understanding of the embodiments of the present invention, a detailed description thereof will be omitted. In addition, although embodiments of the present invention will be described below, the technical idea of ​​the present invention is not limited or restricted thereto, and can be modified and implemented in various ways by those skilled in the art.

[0041] When a part in this specification is said to include a certain component, this does not exclude other components, unless otherwise specifically stated, but rather means that other components may be included. In this specification, the term "and / or" includes a combination of multiple related items or any one of multiple related items.

[0042] In this specification, “core-shell multiple emulsion” means an emulsion including a first phase corresponding to a single core as the innermost phase, a second phase corresponding to a shell surrounding the core, and a third phase corresponding to a continuous phase.

[0043] In this specification, “polyol” refers to a general term for components containing a hydroxyl group (-OH) in the molecule, and refers to components such as monoalcohol, dialcohol, and trialcohol.

[0044] In this specification, “first oil phase” means an oil phase located in the core, which is the inner phase of a core-shell multiple emulsion.

[0045] In this specification, “second oil phase” means the oil phase of the external continuous phase of the core-shell multiple emulsion.

[0046] In this specification, “bi-continuous phase” means a phase in which oil droplets, a water-phase continuous phase, and an oil-phase continuous phase coexist.

[0047] The core-shell multiple emulsion (CSME) of the present invention can have a high inner phase occupancy rate because the inner phase is composed of a single core with excellent stability. Accordingly, the inner phase can contain a high content of effective ingredients.

[0048] Fig. 1 is a schematic diagram of the form of the core-shell multiple emulsion of the present invention. As shown in Fig. 1, the first oil phase may be located in the innermost phase corresponding to the core of the core-shell multiple emulsion, the water phase may correspond to the shell and surround the core, and the outermost phase may be composed of the second oil phase.

[0049] The core-shell multiple emulsion of the present invention may include an aqueous phase, a first oil phase, and a second oil phase. The aqueous phase may include a thickener, and the first oil phase and the second oil phase may include oil, a polyol, and a surfactant.

[0050] The water-soluble part of the present invention is a phase that constitutes a shell surrounding a core in a core-shell multiple emulsion, and includes a thickener.

[0051] The thickener of the present invention can increase the stability of oil droplets by surrounding them in both continuous phases. Therefore, the amount of oil phase input that maintains both continuous phases without phase inversion can be increased. The oil droplets surrounded by the thickener can form the core of a core-shell structure.

[0052] Fig. 2a is a schematic diagram showing the process of forming a core-shell multiple emulsion by surrounding the oil droplets in the oil phase in the water phase with the thickener in the two continuous phases, and Fig. 2b is a schematic diagram showing the process of forming a water-in-oil emulsion through the two continuous phases when the thickener is not included. According to Fig. 2a, when the thickener is included in the water phase, the oil droplets in the oil phase in the water phase are surrounded by the thickener in both continuous phases, so that the oil-in-water phase in the oil phase does not undergo phase inversion to water-in-oil phase, but becomes the core of a core-shell, thereby forming a CSME. On the other hand, according to Fig. 2b, when the thickener is not included in the water phase, phase inversion occurs upon introduction of the oil phase, so that a water-in-oil emulsion is formed without forming a CSME.

[0053] An example of the range in which both continuous phases can be formed according to the volume fraction of the oil phase injected in Fig. 3 is shown, differentiated according to whether or not a thickener is included. According to Fig. 3, when a thickener is included in the water phase, the range in which both continuous phases are formed is relatively wide, so that a large amount of oil phase can be injected without phase inversion occurring.

[0054] In an embodiment, the thickener may include a water-soluble thickener. The water-soluble thickener may include any commonly used water-soluble thickener. For example, the thickener may include, but is not limited to, one or more selected from the group consisting of agar, xanthan gum, gellan gum, carbomer, acrylate copolymer-6 and acrylates / C10-30 acrylate crosspolymer, acrylic acid / VP crosspolymer, hydroxyethylcellulose, hydroxypropylcellulose, hydroxypropylmethylcellulose, cellulose gum, tara gum, sclerotium gum, arabic gum, guar gum, ethylcellulose, cellulose, carboxymethyl cellulose, methylhydroxyethyl cellulose, hydrolyzates thereof, and mixtures thereof.

[0055] In the embodiment, the thickener may be included in an optimal amount for each thickener component. The optimal amount can be easily selected by those skilled in the art without compromising the purpose and effects of the present invention.

[0056] For example, when agar is used as a thickening agent, it may be included in an amount of 1.4 wt% or less based on the total weight of the core-shell multiple emulsion.

[0057] The first oil phase of the present invention may correspond to a phase constituting the core, which is the innermost phase of a core-shell multiple emulsion. The first oil phase may include oil, polyol, and a surfactant.

[0058] The oil of the present invention may correspond to an oily solvent.

[0059] In the embodiment, the oil may include all commonly used oils. For example, the oil may be selected from silicone oils, hydrocarbon oils, and ester oils. In addition, examples of the silicone oil include at least one selected from cyclopentasiloxane, cyclohexasiloxane, disiloxane, methyl trimethicone, and dimethicone; examples of the hydrocarbon oil include at least one selected from isododecane and isohexadecane; and examples of the ester oil include at least one selected from dibutyl adipate, isopropyl palmitate, and diisopropyl sebacate. However, the present invention is not limited thereto. In addition, the oil may also include an oil-soluble UV-blocking ingredient. Examples of the oil-soluble UV-blocking ingredient include ethylhexyl salicylate, ethylhexyl methoxycinnamate, homosalate, and octoclinene. However, the present invention is not limited thereto.

[0060] The polyol of the present invention can exist as droplets in the form of an oil-in-polyol within the oil phase due to the oil and surfactant. In the oil-in-polyol form, when the interfacial tension increases due to an increase in the amount of the oil phase, the surfactant moves to the interface between the water phase and the oil phase, so that the surfactant forming the reverse micelle can be located at the interface between the oil phase and the water phase and play a role in forming two continuous phases. In addition, when it plays the role as described above, the increase in the volume fraction of the entire oil phase due to the addition of the oil phase to the water phase can be smaller than the amount added, and in addition, as the hydrogen bond of the surfactant that emulsifies the polyol becomes relatively stronger during the cooling process, the surfactant that emulsifies the polyol moves to the interface between the water phase and the oil phase, and accordingly, the polyol is also released from the oil phase to the water phase, so that the volume fraction of the entire oil phase within the composition can decrease. Therefore, the amount of the oil phase that can be added while maintaining both continuous phases can increase, and the two continuous phases can be maintained for a longer time during the cooling process.

[0061] The schematic diagram in Figure 4 illustrates the reverse micelle configuration contained in the oil phase when the oil-in-oil polyol meets the water phase and the movement of the surfactant used for polyol emulsification. The reverse micelle-type surfactants move to the interface, and the surfactant that emulsifies the polyol also moves thereafter, and accordingly, the polyol is released from the oil phase to the water phase.

[0062] FIG. 5 shows a modified graph showing that when a polyol is included in the oil phase, the amount of the oil phase can be increased while maintaining the two continuous phases. According to FIG. 5, when a polyol is not included in the oil phase, a phase inversion phenomenon occurs when a certain amount of the oil phase is added, and the inverted phases are still maintained upon cooling, whereas when a polyol is included in the oil phase, the process proceeds through a widened area of ​​the two continuous phases as the surfactant and polyol move from the oil phase to the interface or water phase.

[0063] During the oil phase injection process, the surfactant is located at the interface, and as a result, the polyol is released from the oil phase to the water phase, so the increase in the ratio of the oil phase is reduced compared to the actual oil phase injection amount, and as the hydrogen bond becomes relatively strong during the cooling process, the surfactant is located at the interface, and as a result, the polyol is released out of the oil phase, so the overall volume fraction of the oil phase can decrease.

[0064] In an embodiment, the polyol may include, but is not limited to, one or more selected from the group consisting of monoalcohols and polyhydric alcohols having less than 7 carbon atoms. Examples of the components may include at least one of ethanol, butylene glycol, dipropylene glycol, propanediol, and glycerin. In addition, when one of the components is included as the polyol, a polyol that does not form a core-shell multiple emulsion when introduced alone may be mixed and used. For example, when butylene glycol is used as the polyol, 1,2-octanediol may be further added.

[0065] In an embodiment, the polyol may be included in an amount of 2 to 35 wt%, specifically 3 to 30 wt%, more specifically 5 to 25 wt%, and most specifically 5 to 15 wt%, based on the total weight of the core-shell multiple emulsion. If the polyol is included in an amount of less than 3 wt%, CSME formation may not be possible, and if it is included in an amount of more than 35 wt%, the two continuous phase regions may not be reached, and thus the core-shell structure may not be formed.

[0066] The surfactant of the present invention can perform various roles depending on the process step. The surfactant in excess within the oil phase can exist in the oil phase in the form of reverse micelles and emulsify the polyol within the oil phase. In addition, when the oil phase forms an interface with the water phase, the surfactant can move to the interface and maintain both continuous phases. When forming a core-shell type emulsion, the surfactant can emulsify the outermost oil phase as a water-in-oil emulsifier. In addition, when the content of the surfactant increases, the shell thickness of the core-shell multiple emulsion can decrease, and thus the shell thickness can be controlled by adjusting the content of the surfactant.

[0067] Figure 6 shows a graph showing changes in cell thickness according to the content of surfactant. According to Figure 6, it can be seen that when the content of surfactant increases, the thickness of the core does not change, but the thickness of the shell decreases.

[0068] In the embodiment, the surfactant may be compatible with the oil. As used herein, "compatible" is defined as two raw materials that do not become opaque when mixed. For example, when silicone oil is used as the oil and a silicone-based surfactant is used as the surfactant, the two components are compatible with each other, resulting in a formulation that is not opaque.

[0069] In an embodiment, the hydrophilic group of the surfactant may be selected from the group consisting of a polyethylene glycol (PEG) group, a polypropylene glycol (PPG) group, a polyethylene glycol / polypropylene glycol (PEG / PPG) group, a polyglyceryl group, and a sorbitan group, but is not limited thereto.

[0070] In the embodiment, the hydrophobic group of the surfactant may be selected from the group consisting of a silicone main chain, a branched silicone main chain, and a silicone main chain crosslinked with an alkyl group, but is not limited thereto.

[0071] In the embodiment, the surfactant may include at least one type that is compatible with the oil, and may also include another type that is not compatible. For example, when using a silicone-based oil, a silicone-based surfactant and a hydrocarbon-based surfactant may be mixed and used.

[0072] In an embodiment, the surfactant may be included in an amount of 0.5 to 15 wt%, specifically 1 to 13 wt%, more specifically 1.5 to 11 wt%, and most specifically 2.0 to 10 wt%, based on the total weight of the core-shell multiple emulsion. If the surfactant is included in an amount of less than 0.5 wt%, the two continuous phases may not be maintained, and thus CSME may not be formed. If the surfactant is included in an amount of more than 15 wt%, the polyol may not be released from the oil phase to the water phase, and thus a wide range of two continuous phases may not be formed, and thus CSME may not be formed.

[0073] The first oil phase, which corresponds to the innermost phase of the core-shell multiple emulsion of the present invention, may further include an aqueous phase. The aqueous phase may be formed because, in the manufacturing process of the core-shell multiple emulsion, the polyol of the first oil phase may have hydrophilic properties, allowing the aqueous phase to be incorporated into the interior of the first oil phase.

[0074] The second oil phase of the present invention corresponds to the traumatic continuous phase. The second oil phase is derived from the first oil phase and may be composed of the same components as the first oil phase. Specifically, the second oil phase corresponds to the first oil phase that did not become the core during the core-shell multiple emulsion manufacturing process.

[0075] At least one of the first oil phase and the second oil phase of the core-shell multiple emulsion of the present invention may further comprise a UV-blocking agent. When the UV-blocking agent is included, the UV-blocking efficacy of the core-shell multiple emulsion may be uniform.

[0076] In Fig. 7, it was shown that the UV blocking efficacy can be uniformly applied when a lipophilic UV blocking component is applied to the core-shell multiple emulsion of the present invention and when both lipophilic and hydrophilic UV blocking components are applied, compared to the case of a water-in-oil emulsion. As shown in Fig. 7, the core-shell multiple emulsion showed excellent UV blocking efficacy regardless of whether external UV rays passed through the CSME or the size of the CSME, whereas in the case of a general water-in-oil emulsion, the UV blocking efficacy was significantly reduced when external UV rays passed through the water-in-oil emulsion compared to when they did not pass through the emulsion. In addition, it was shown that the CSME can improve the dispersibility of the hydrophilic UV blocking component corresponding to the shell.

[0077] According to an embodiment of the present invention, a cosmetic composition comprising the core-shell multiple emulsion of the present invention is provided.

[0078] In addition, the cosmetic composition according to the present invention can be manufactured in one or more formulations selected from the group consisting of skin lotion, skin softener, skin toner, lotion, milk lotion, moisture lotion, nutrition lotion, massage cream, nutrition cream, moisture cream, hand cream, foundation, essence, nutrition essence, pack, soap, cleansing foam, cleansing lotion, cleansing cream, body lotion, and body cleanser.

[0079] According to an embodiment, the cosmetic composition according to the present invention may additionally include, in addition to the above components, components included in general cosmetic compositions, such as preservatives, functional ingredients, ion sequestrants, bactericides, pH regulators, antioxidants, plant extracts, fragrances, cooling agents, additives, etc., but are not limited thereto. The blending amount of the above components is not particularly limited, and can be easily selected by those skilled in the art within a range that does not impair the purpose and effects of the present invention.

[0080] In another embodiment of the present invention, a method for preparing a core-shell multiple emulsion is provided.

[0081] The core-shell multiple emulsion manufacturing method of the present invention can be carried out in a wide range of bi-continuous phases, so that phase inversion does not occur quickly as the amount of oil phase added increases, and thus the oil-in-water emulsion particles can be maintained in the form of emulsion particles in the bi-continuous phase region. The oil-in-water emulsion particles that maintain their form as described above can form the core of CSME and the water phase around the core can form the shell when phase inversion occurs, thereby forming CSME. In addition, the core-shell multiple emulsion manufacturing method by the above manufacturing method can be applied to a mass production process.

[0082] The core-shell multiple emulsion manufactured by the manufacturing method of the present invention has a large inner phase occupancy rate and can contain a high content of an effective ingredient.

[0083] The method for producing a core-shell multiple emulsion of the present invention may include the steps of (S1) adding an oil phase to an aqueous phase to produce a mixture of two continuous phases; and (S2) adding the oil phase to the mixture of two continuous phases produced in step S1 to form a core-shell multiple emulsion comprising a first oil phase forming a core, an aqueous phase forming a shell, and a second oil phase forming a second continuous phase.

[0084] Step S1 of the present invention corresponds to a step of introducing an oil phase into an aqueous phase. Specifically, when step S1 is performed, when the ratio of the oil phase is low, oil droplets in an oil-in-water phase are formed, and the polyol in the oil phase is released into the water phase to reach a low interfacial tension, thereby maintaining a low interfacial tension. When the ratio of the oil phase increases, some of the droplets can coalesce to form a flexible continuous phase. Since the release of the polyol continues to progress and a low interfacial tension state is maintained, an instantaneous phase reversal does not occur, and a bicontinuous phase can be formed in which the first oil phase, which is an oil droplet, the water phase continuous phase, and the second oil phase, which is an oil-in-water continuous phase, coexist.

[0085] In an embodiment, the aqueous phase of step S1 may include a water-soluble thickener. The water-soluble thickener can surround the oil droplets of the oil phase in both continuous phases, thereby increasing the stability of the oil droplets. This stability indicates that the droplet state can be maintained even when the amount of oil phase added increases. The aqueous phase may be prepared by mixing purified water and a thickener.

[0086] In an embodiment, the oil phase of step S1 may include oil, polyol, and surfactant.

[0087] Specifically, the above-mentioned oil phase can be emulsified by adding a polyol and a surfactant to oil, thereby forming an oil droplet formulation of polyol-in-oil type.

[0088] Step S2 of the present invention may correspond to a step in which a core-shell multiple emulsion is formed by further adding an oil phase to the mixture of both continuous phases formed in step S1, such that oil droplets surrounded by a thickener in the aqueous phase form the core of the CSME, and the aqueous phase forms a shell surrounding the core. Specifically, step S2 may correspond to a step in which an oil phase is further added to the mixture of both continuous phases formed in step S1, such that interfacial tension increases, so that the oil droplets form the core, the aqueous phase surrounding the core forms a shell, and the oil phase that does not form the core can be united to form a continuous phase.

[0089] The above S2 step may not be performed separately from the S1 step and may be performed continuously by controlling the injection speed of the first oil phase.

[0090] FIG. 8 is a schematic diagram illustrating the formation of oil-in-water-in-oil (O / W / O) emulsion particles in the above-described two-phase continuous phase. According to FIG. 8, as both continuous phases are maintained, oil-in-water oil droplets can maintain their shape without phase inversion and thus can become the core (first oil phase) of a core-shell. As more of the first oil phase is added according to the S2 step, the water-phase continuous phase can become a shell (water phase) surrounding the core. As the amount of the oil phase added increases, the first oil phase that is not able to become the core and is united becomes the oil-phase continuous phase (outer phase; second oil phase), thereby forming core-shell oil-in-water-in-oil emulsion particles.

[0091] In an embodiment, the S1 step and / or the S2 step may be performed at a high temperature of 52°C or higher. When performed within the above temperature range, both continuous phases can be maintained even with a high oil phase input amount.

[0092] In an embodiment, the S1 step and / or the S2 step may be performed while stirring. When performed while stirring, the coalescence of oil phases can be suppressed, thereby efficiently forming CSME. In addition, when the stirring speed is increased, the radius of the initial oil phase droplets can be reduced, thereby reducing the radius of the CSME ultimately formed. Therefore, the size of the CSME can be controlled by adjusting the stirring speed.

[0093] Figure 9 shows a graph of the change in the radius of the CSME according to the stirring speed. According to Figure 9, when the stirring speed increases, the thickness of the shell with respect to the CSME radius does not change, but it can be confirmed that the radius of the CSME gradually decreases.

[0094] In an embodiment, the stirring speed of the S1 step and / or the S2 step may be 8900 rpm or less, specifically 8500 rpm or less, and more specifically 8000 rpm or less. If the stirring speed exceeds 8900 rpm, the CSME may not be formed because the radius becomes smaller than the minimum radius of the CSME at which oil droplets can be formed.

[0095] The manufacturing method of the present invention may further include (S3) a step of cooling the core-shell multiple emulsion manufactured in step S2. Specifically, in step S3, although the energy of the emulsion system as a whole decreases due to cooling, the strength of the hydrogen bond between the hydrophilic groups of the polyol and surfactant components becomes relatively strong, so that the polyol and surfactant included in the first oil phase and the second oil phase can be released into the interface or the water phase. Therefore, when step S3 is performed, the volume fraction of the oil phase of the entire core-shell multiple emulsion can decrease, and the CSME can become more stable due to the movement of the polyol and surfactant remaining in the first oil phase and the second oil phase.

[0096] In an embodiment, the S3 step may be performed with stirring.

[0097] In an embodiment, the S3 step may be cooled at a rate of 30°C / min, specifically 20°C / min, and more specifically 15°C / min.

[0098] Hereinafter, examples and experimental examples are presented to explain the present invention more specifically, but the present invention is not limited thereto.

[0099] Manufacturing example. Manufacturing of Example 1

[0100] A core-shell multiple emulsion according to the present invention was prepared using the components listed in Table 1 below. Specifically, agar was used as a thickener in the water phase, cyclopentasiloxane was used as an oil in the oil phase, butylene glycol was used as a polyol, and PEG-9 polydimethylsiloxyethyl dimethicone was used as a surfactant. The contents in Table 1 are in wt%.

[0101] [Table 1]

[0102]

[0103] The specific manufacturing method is as follows.

[0104] The water phase and the oil phase are heated to 90°C. (S1-S2) The water phase is stirred at 150 rpm using a homogenizer, and the oil phase is added over 15 seconds, and stirred for an additional minute. (S3) The mixture is then stirred and cooled to 25°C at a cooling rate of 1°C / min to complete Example 1.

[0105] The manufactured Example 1 was observed under a microscope to confirm whether CSME was formed. Specifically, the formation of CSME was confirmed by observing at a magnification of 100 to 1000 times using OLYMPUS BX53. As a result, it was confirmed that a large number of core-shell multiple emulsion particles were formed, each composed of a first oil phase forming a core, an aqueous phase forming a shell, and a second oil phase forming a continuous oil phase. A microscope photograph of Example 1 is shown in Fig. 10.

[0106] Experimental Example 1. Comparative experiment on the formation of CSME according to the phase containing polyol during the manufacturing process.

[0107] In order to confirm whether CSME is formed depending on whether the monoalcohol and polyol of the present invention are included in the oil phase and / or the water phase during the manufacturing process, examples and comparative examples were manufactured using butylene glycol in the oil phase and / or the water phase, and then it was observed whether a core-shell multiple emulsion was formed. Specifically, as described in Table 2, the total content of butylene glycol was all the same, and three examples and comparative examples were manufactured: a case where butylene glycol was included only in the oil phase, a case where butylene glycol was included in both the oil phase and the water phase, and a case where butylene glycol was included only in the water phase. The manufacturing method and the formulation observation method of the examples and comparative examples are the same as those of the above manufacturing examples.

[0108] In order to evaluate whether the formulation was well formed, the formation of the formulation was evaluated using the evaluation criteria shown in Table 2 below.

[0109] [Table 2]

[0110]

[0111] Table 3 below shows whether the aqueous and oily phases of the examples and comparative examples contained butylene glycol, and the observed formulations.

[0112] [Table 3]

[0113]

[0114] As shown in Table 3 above, all examples including butylene glycol in the oil phase were confirmed to stably form a CSME including a water phase, a first oil phase, and a second oil phase, whereas Comparative Example 1, which did not include butylene glycol in the oil phase, was confirmed to form a water-in-oil type emulsion.

[0115] Therefore, according to the above experimental results, it can be confirmed that the inclusion of polyol in the oil phase is an important component in the formation of the CSME of the present invention.

[0116] Experimental Example 2. Comparative experiment on the formation of CSME according to the type of thickener in the water column.

[0117] In order to confirm whether CSME is formed according to the type of thickener included in the aqueous phase of the present invention, examples were prepared with different types of thickeners, and then it was observed whether a core-shell multiple emulsion was formed. Specifically, based on Example 1, the thickener in the aqueous phase was one of Carbomer, Acrylates / C10-30 Alkyl Acrylate Crosspolymer, Xanthan gum, and Ammonium Acryloyldimethyltaurate / VP Copolymer, and the remaining ingredients and contents were the same. The manufacturing method and the method of observing the formulation of the example are the same as in the above manufacturing example. The types of thickeners of the examples and the observed formulations are shown in Table 4 below.

[0118] [Table 4]

[0119]

[0120] As shown in Table 4 above, all examples including an appropriate thickener in the water column were confirmed to form CSME stably.

[0121] Therefore, according to the above experimental results, it can be confirmed that the type of thickener included in the water-soluble thickener is an important component in the formation of the CSME of the present invention.

[0122] Experimental Example 3. Comparative experiment on the formation of CSME according to the presence and type of polyol in the oil phase.

[0123] In order to confirm whether CSME is formed depending on the type of polyol in the oil phase of the present invention, examples and comparative examples were prepared by changing the type of polyol, and then it was observed whether a core-shell multiple emulsion was formed. Specifically, based on the components of Example 1, one type of polyol among butylene glycol, dipropylene glycol, propanediol, 1,2-octanediol, ethanol, and stearyl alcohol was used in the same content. In addition, when butylene glycol and another polyol were used as two types of polyol, the weight of butylene glycol was 7 wt%, the weight of the other polyol was 6 wt%, and the remaining components and contents were the same. The manufacturing method and the method of observing the formulation of the examples and comparative examples are the same as the above manufacturing example. The types of polyols of the examples and comparative examples and the observed formulations are shown in Table 5 below.

[0124] [Table 5]

[0125]

[0126] As shown in Table 5 above, it was confirmed that all examples including a monoalcohol or polyalcohol having less than 7 carbon atoms in the oil phase stably formed a CSME including a water phase, a first oil phase, and a second oil phase, whereas in the case of Comparative Examples 2 and 3 including 1,2-octanediol or stearyl alcohol alone as the polyol, a water-in-oil type emulsion was formed.

[0127] Therefore, according to the above experimental results, it can be confirmed that the type of polyol in the oil phase corresponds to an important component in the formation of the CSME of the present invention.

[0128] Experimental Example 4. Comparative Experiment on CSME Formation According to Oil Type and Surfactant Type

[0129] (1) Type of oil

[0130] In order to confirm whether CSME is formed according to the type of oil in the oil phase of the present invention, examples and comparative examples were prepared by changing the type of oil based on Example 1, and then it was observed whether a core-shell multiple emulsion was formed.

[0131] In this experiment, a silicone-based surfactant was used as a surfactant, and since compatibility with surfactants may differ depending on the oil series, one of cyclopentasiloxane, cyclohexasiloxane, disiloxane, methyl trimethicone, and dimethicone was used as a silicone-based oil; one of dibutyl adipate, isopropyl palmitate, diisopropyl sebacate, ethylhexyl salicylate, and ethylhexyl methoxycinnamate was used as an ester-based oil; and one of hydrogenated polyisobutene, mineral oil, and squalane was used as a hydrocarbon-based oil. The remaining ingredients and contents were the same. The manufacturing method and the formulation observation method of the examples and comparative examples were the same as those of the above manufacturing examples. The types of oils of the examples and comparative examples and the observed formulations are shown in Table 6 below.

[0132] [Table 6]

[0133]

[0134] As shown in Table 6 above, it was confirmed that Examples 1 and 15 to 18 using silicone oils formed well core-shell multiple emulsions, Example 19 using dibutyl adipate among ester oils formed a core-shell structure although the CSME particles were slightly distorted, and Examples 20 to 23 using other ester oils formed a core-shell structure although the CSME particles were relatively small in proportion. On the other hand, it was confirmed that water-in-oil type emulsions were formed in Comparative Examples 6 to 8 using hydrocarbon oils.

[0135] In light of the above experimental results, it was confirmed that when a silicone-based surfactant was used, a commercially available silicone-based oil could form CSME most effectively, indicating that whether the surfactant and oil are compatible with each other is an important factor in the formation of a core-shell structure.

[0136] (2) Type of surfactant

[0137] In order to confirm whether CSME is formed according to the type of surfactant in the oil phase of the present invention, examples and comparative examples were prepared by varying the types of surfactants based on Example 1, and then it was confirmed whether core-shell multiple emulsions were formed. Specifically, one type of silicone-based surfactant and one type of hydrocarbon-based surfactant were used, and the remaining ingredients and contents were the same. The manufacturing method and formulation observation method of the examples and comparative examples were the same as those in the above manufacturing example.

[0138] In this experiment, oil and silicone-based oil were used, and compatibility with oil may vary depending on the type of surfactant. Table 7 below shows the types of surfactants used in the examples and comparative examples, as well as the observed formulations.

[0139] [Table 7]

[0140]

[0141] As shown in Table 7 above, it was confirmed that core-shell multiple emulsions were well formed in Examples 1 and 24 to 30 using silicone-based surfactants, whereas water-in-oil type emulsions were formed in Comparative Examples 7 to 16 using hydrocarbon-based surfactants.

[0142] In light of the above experimental results, it was confirmed that CSME could be effectively formed when a commercially available silicone-based surfactant was used in the case of using silicone-based oil.

[0143] (3) Use of a mixture of two types of surfactants

[0144] In order to confirm whether CSME is formed when two types of surfactants of the same series as the oil are used as the surfactant of the oil phase of the present invention, or one type of surfactant of the same series as the oil and one type of surfactant of a different series are mixed and used, examples and comparative examples were prepared by changing the types of surfactants based on Example 1, and then it was confirmed whether a core-shell multiple emulsion was formed. Specifically, two types of silicone surfactants were used, or one type of silicone surfactant and one type of hydrocarbon surfactant were used, and each was mixed at 2.5 wt%, and the remaining components and contents were the same. The manufacturing method and the formulation observation method of the examples and comparative examples are the same as the above manufacturing example.

[0145] According to the criteria of Table 5 above, the types of surfactants and observed formulations of examples and comparative examples are indicated in Table 8 below.

[0146] [Table 8]

[0147]

[0148] As shown in Table 8 above, it was confirmed that core-shell multiple emulsions were well formed in both Examples 31 to 35 using two types of silicone-based surfactants and Examples 36 to 39 using one type of silicone-based surfactant and one type of hydrocarbon-based surfactant.

[0149] In light of the above experimental results, it was confirmed that when a commercially available silicone-based surfactant is used, CSME can be effectively formed even when a surfactant of a different series is additionally included when a silicone-based oil is used.

[0150] Therefore, according to the above three experimental results, it was confirmed that the type of oil and the type of surfactant corresponding to it are important components in the formation of the CSME of the present invention.

[0151] Experimental Example 5. Comparative Experiment on CSME Formation According to Thickener, Polyol, and Surfactant Contents

[0152] In order to confirm the optimal content of thickener, polyol, and surfactant in the formation of CSME of the present invention, examples and comparative examples were prepared by varying the content of thickener, polyol, and surfactant, respectively, and then it was confirmed whether a core-shell multiple emulsion was formed. Specifically, based on Example 1, examples and comparative examples were prepared by varying the content of agar as a thickener, varying the content of butylene glycol as a polyol, and varying the content of PEG-9 polydimethylsiloxyethyl dimethicone as a surfactant, and the remaining ingredients and contents were the same. The manufacturing method and the formulation observation method of the examples and comparative examples are the same as those of the above manufacturing examples. The ingredients and contents of the examples and comparative examples are shown in Table 9 below.

[0153] [Table 9]

[0154]

[0155] The examples and comparative examples manufactured with the ingredients and contents described in Table 9 above were observed to form core-shell multiple emulsions well, and are shown in Table 10 below.

[0156] [Table 10]

[0157]

[0158] As shown in Table 10 above, it was confirmed that CSME was formed in all examples including the appropriate amount of thickener, polyol, and surfactant. Specifically, in the case of the thickener, Examples 40 and 41 including the appropriate amount of thickener formed CSME well, whereas Comparative Example 17 without the thickener and Comparative Example 18 with an excessive amount of thickener did not form CSME. In the case of the polyol, it was confirmed that CSME was formed when the appropriate amount of polyol was used in Examples 42 to 44 and Comparative Example 20, but the ratio of CSME decreased as the polyol content increased, and in the case of Comparative Example 19 without the polyol, it was confirmed that CSME was not formed. In the case of surfactants, it was confirmed that CSME was formed when an appropriate amount of surfactant was used in Examples 45 to 47, but that the CSME was distorted as the surfactant ratio increased. In the case of Comparative Example 21, where no surfactant was used, and Comparative Example 22, where an excessive amount of surfactant was used, it was confirmed that CSME was not formed.

[0159] Therefore, according to the above experimental results, it can be confirmed that the appropriate content of thickener, polyol, and surfactant is an important component in forming the CSME of the present invention.

[0160] While specific aspects of the present invention have been described in detail above, it will be apparent to those skilled in the art that these specific descriptions merely represent preferred embodiments and are not intended to limit the scope of the present invention. Therefore, the substantial scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. In core-shell multiple emulsion, It comprises a first oily portion forming a core; a watery portion forming a shell; and a second oily portion forming a traumatic continuous phase; The above-mentioned award comprises a thickener, A core-shell multiple emulsion, wherein the first oil phase and the second oil phase comprise oil, polyol and a surfactant.

2. In paragraph 1, A core-shell multiple emulsion, characterized in that the thickener is a water-soluble thickener.

3. In paragraph 1, The above oil is a core-shell multiple emulsion selected from silicone oil, hydrocarbon oil and ester oil.

4. In paragraph 1, A core-shell multiple emulsion, wherein the polyol is contained in an amount of 2 to 35 wt% based on the total weight of the core-shell multiple emulsion.

5. In paragraph 1, A core-shell multiple emulsion, wherein the surfactant is contained in an amount of 0.5 to 15 wt% based on the total weight of the core-shell multiple emulsion.

6. In paragraph 1, A core-shell multiple emulsion, wherein the thickener comprises at least one of agar, carbomer, xanthan gum, gellan gum, acrylate copolymer-6, and acrylate / C10-30 acrylate crosspolymer.

7. In paragraph 1, A core-shell multiple emulsion, wherein the polyol comprises one or more selected from the group consisting of monoalcohols and polyhydric alcohols having less than 7 carbon atoms.

8. In paragraph 1, A core-shell multiple emulsion comprising at least one surfactant that is compatible with the oil.

9. In paragraph 1, A core-shell multiple emulsion, wherein at least one of the first oil phase and the second oil phase further comprises a UV-blocking agent.

10. In the method for producing a core-shell multiple emulsion, (S1) A step of producing a bi-continuous phase mixture by adding a liquid phase to a water phase; (S2) A method for producing a core-shell multiple emulsion, comprising: a step of further adding the oil phase to the mixture of the two continuous phases produced in the step S1 to form a core-shell multiple emulsion comprising a first oil phase forming a core, an aqueous phase forming a shell, and a second oil phase forming an external continuous phase.

11. In Article 10, The above core-shell multiple emulsion manufacturing method is, (S3) A method for producing a core-shell multiple emulsion, further comprising a step of cooling the core-shell multiple emulsion produced in the step S2.

12. In paragraph 10, The water-soluble thickener of the above step S1 is a core-shell multiple emulsion containing a water-soluble thickener.

13. In paragraph 10, A method for producing a core-shell multiple emulsion, wherein the oil phase of the above step S1 comprises: oil; at least one polyol; and a surfactant.

14. A cosmetic composition comprising a core-shell multiple emulsion according to any one of claims 1 to 10.

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