Patent Application
20250073146
This application claims priority to Korean Patent Application No. 10-2023-0116230 filed Sep. 1, 2023, the entire disclosures of which are incorporated herein by reference.
The present invention relates to a mixed surfactant for preparing a transparent microemulsion and a fine nanoemulsion without using a certain high-pressure microfluidizer, and a cosmetic composition prepared using the same.
A general method of preparing a liposome or nanoemulsion in the cosmetics industry includes stirring a mixture of oil and water using hydrogenated lecithin as a surfactant and then allowing the mixture to pass through a high-pressure microfluidizer (1 to 6 times) to obtain the nanoemulsion.
Recently, there has been actively reported research on phenomena occurring at the interface related to the formation of irregular emulsified particles on the micron (μm) scale that occur in a mixed system of a surfactant, an oil, and water. It has been reported that regions where cubic phase, hexagonal phase, and multilayered lamellar structures are formed can be optionally obtained through a three-phase system (general term for the surfactant: oil (oil phase): water (aqueous phase)) under predetermined conditions. In particular, there are known many cases in which monovesicular or multilayer lamellar vesicles are formed in mixed systems using hydrogenated lecithin.
Methods of preparing nanoemulsions or forming transparent microemulsions in the conventional three-phase surfactant system are disadvantageously very difficult. To solve this disadvantage, it is important to develop surfactants and there is a need for development of methods that are capable of preparing nanoemulsions from lipophilic substances by simply stirring oil and aqueous phases in the presence of a surfactant, and methods that are capable of preparing transparent microemulsions.
In order to solve the problems of the prior art as described above, it is one object of the present invention to provide a surfactant for producing transparent microemulsions by simple stirring and fine nanoemulsions by simple operation.
In addition, it is another object of the present invention to provide a cosmetic composition such as skin toner, lotion, cream, essence, ampoule, or mask sheet containing the transparent microemulsion and the fine nanoemulsion.
In accordance with one aspect of the present invention, provided is a mixed surfactant for preparing an emulsion, the mixed surfactant containing sucrose distearate and polyglyceryl-10 oleate.
In accordance with another aspect of the present invention, provided is an emulsion prepared by mixing a mixed surfactant containing sucrose distearate and polyglyceryl-10 oleate with an oily phase and an aqueous phase, followed by stirring.
In an embodiment, the emulsion may be a transparent emulsion or a nanoemulsion.
In accordance with another aspect of the present invention, provided is a cosmetic composition containing the emulsion according to the present invention.
In accordance with another aspect of the present invention, provided is a nanoemulsion prepared by diluting the transparent emulsion according to the present invention in an aqueous phase.
In accordance with another aspect of the present invention, provided is a cosmetic composition containing the nanoemulsion according to the present invention.
The above and other objects, features and other advantages of the present invention will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings, in which:
Hereinafter, the present invention will be described in more detail with reference to the annexed drawings.
Microemulsions and nanoemulsions can be prepared by simple mixing and stirring the mixed surfactant according to the present invention without using a certain high-pressure microfluidizer. The microemulsion prepared herein was a transparent microemulsion and the nanoemulsion prepared herein was a fine nanoemulsion.
According to the method for preparing transparent microemulsions and fine nanoemulsions according to the present invention, transparent microemulsions or fine nanoemulsions can be prepared by selecting a high-purity mixed surfactant and an oil, and adding an aqueous phase mixed with purified water or glycerin thereto.
Based on this research, the present invention provides a mixed surfactant for preparing an emulsion containing sucrose distearate and polyglyceryl-10 oleate.
Meanwhile, the present invention is an emulsion prepared by mixing the mixed surfactant containing sucrose fatty acid ester and polyglyceryl-10 fatty acid ester, an oil phase and an aqueous phase, followed by stirring.
By controlling the addition ratio of the mixed surfactant, the oil phase, and the aqueous phase, the emulsion of the present invention may be prepared as a transparent microemulsion or nanoemulsion. In particular, the addition ratio of the aqueous phase may greatly affect preparation of the microemulsion or nanoemulsion.
Meanwhile, the present invention provides a nanoemulsion prepared by diluting the transparent microemulsion of the present invention in an aqueous phase. When the microemulsion prepared according to the present invention is diluted in the aqueous phase, it can be easily phase-changed to the nanoemulsion. Another feature of the present invention is that phase change can be achieved through such a simple operation.
Meanwhile, the present invention provides a cosmetic composition containing the emulsion, the microemulsion or the nanoemulsion of the present invention.
The emulsion of the present invention may be used in skin toners, lotions, emulsions, creams, essences, ampoules or mask sheets, and the like to facilitate percutaneous absorption of useful substances and provide excellent effects on the skin of obtaining moisturizing effects, supplying nutrition, adjusting pH, controlling skin oil-moisture balance, alleviating fine wrinkles, and improving whitening and lifting effects.
The preferred embodiments of the present invention will be described in detail for illustrative purposes and those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims.
Hereinafter, embodiments according to the present invention will be described in detail with reference to the attached drawings. Identical or corresponding reference numerals refer to like elements throughout the description of the figures and redundant description thereof will be omitted.
The terms used in the present invention are as follows.
Sucrose, oleic acid, stearic acid, polyglyceryl-10, polyglyceryl-2, fine nanoemulsion, transparent microemulsion, lamellar structure, hexagonal phase (H), cubic phase (Q1), reverse micelle, surfactant phase, sucrose distearate, sucrose distearate, polyglyceryl-10 dioleate, polyglyceryl-10 oleate, polyglyceryl-10 distearate, polyglyceryl-10 stearate, polyglyceryl-2 dioleate, polyglyceryl-2 oleate, oil-in-water (O/W) emulsion, water-in-oil (W/O) emulsion, skin toner, lotion emulsion, essence, ampoule, mask sheet, paddle mixer, homo-mixer, moisturizing effect, pH control, citric acid, oil water balance, skin lifting effect.
General terms not mentioned above will follow the nomenclature of commonly known chemical and cosmetic dictionaries.
According to one embodiment of the present invention, the composition of a surfactant that can be used to prepare a microemulsion or nanoemulsion without using a special high-pressure microfluidizer is summarized in Table 1 below.
As shown in Examples 1 to 7, two or more of sucrose distearate, sucrose dioleate, polyglyceryl-10 stearate, polyglyceryl-10 oleate, polyglyceryl-2 stearate, and polyglyceryl-2 oleate were injected into a reaction tank, the pH was adjusted to a range of 9 to 11 (optimal pH of 9.7), the components were mixed while stirring at 120 to 180° C. for 2 to 4 hours in the presence of nitrogen gas to remove unreacted fatty acids, and the mixture was homogeneously dispersed and mixed.
The resulting mixture was adjusted again to pH 6 to 8 (optimal pH of 6.9), further stirred for 2 hours at 110 to 160° C., and cooled to 50° C. or lower to prepare a mixed surfactant composition of the present invention.
This method will be described in more detail with reference to Example 2. 5 to 40% by weight of sucrose distearate and 40 to 90% by weight of polyglyceryl-10 oleate were mixed, pH was adjusted within the range of 9 to 11 (optimum pH of 9.7), the resulting mixture was stirred for 2 to 4 hours at 120 to 180° C. in the presence of nitrogen gas to remove unreacted substances and the mixture was homogeneously dispersed. The resulting mixture was again adjusted in pH within the range of 6 to 8 (optimal pH of 6.9), further stirred for 2 hours at 110 to 160° C., and cooled to 50° C. or less to complete the preparation.
This method will be described in more detail with reference to Example 2. 30% by weight of sucrose distearate and 70% by weight of polyglyceryl-10 oleate were mixed in the same manner as above to obtain a mixed surfactant enabling preparation of both transparent microemulsions and fine nanoemulsions.
These two surfactants may be a mixture of 5 to 40% by weight of sucrose distearate and 40 to 90% by weight of polyglyceryl-10 oleate. It should be noted that Example 2 is provided only as an example for better understanding, the present invention is not limited thereto and all of Examples 1 to 7 fall within the scope of the present invention.
The process of synthetizing the mixed surfactant is shown in
First, the molecular structures of sucrose and stearic acid for synthesis are shown. Sucrose was derived from sugarcane and stearic acid was derived from coconut. Two stearic acid fatty acids were esterified with sucrose to synthetize sucrose distearate.
Such a method includes mixing 342.3 g/mol of sucrose with 284.48 g/mol of stearic acid at a molar ratio of 1:2, dissolving the resulting mixture by heating to 120 to 180° C., adjusting a pH within 9 to 10.7, binding the fatty acids in the presence of nitrogen gas at 120 to 180° C. for 2 to 4 hours, adjusting the pH within 6 to 8 at 120 to 160° C., and cooling to 50° C. to complete preparation.
Meanwhile, a method for preparing polyglyceryl-10 oleic acid will be described as follows. The method includes mixing 758.8 g/mol of polyglyceryl-10 with 282.468 g/mol of oleic acid at a molar ratio of 1:1, dissolving the mixture by heating to 120 to 160° C., adjusting a pH within 9 to 10.7, binding the fatty acids in the presence of nitrogen gas at 120 to 160° C. for 2 to 4 hours, adjusting the pH within 6 to 8 at 120 to 160° C., and cooling to 50° C. to complete preparation.
The mixed surfactant is prepared by mixing 30% by weight of sucrose distearate prepared as above with 70% by weight of polyglyceryl-10 oleic acid prepared as above, adjusting the pH within 9 to 10.7, binding fatty acids in the presence of nitrogen gas at 120 to 160° C. for 2 to 4 hours, allowing the components to react while stirring to increase purity, adjusting the pH within 6 to 8 and cooling the reaction product to 50° C. or lower to complete preparation.
The high-purity mixed surfactant thus obtained was a light yellow paste with a unique odor, was dissolved when mixed with an oil and then heated, and had an HLB of 10.2 to 13.2. More specifically, polyglyceryl-10 oleate, which is one surfactant, has an HLB of 12.0 to 13.2 (average HLB=12.5), and sucrose distearate, which is the other surfactant, has an HLB of 4.5 to 6.9 (average HLB=6.3). When this surfactant is mixed with an oil, dissolved therein and then mixed with purified water, a transparent microemulsion can be formed by simple stirring.
In addition, the mixed surfactant is dissolved in glycerin, and an oil is added thereto, followed by stirring. When the phase transition temperature is reached to obtain a transparent nanoemulsion, the transparent nanoemulsion is stirred in the presence of prepared purified water to prepare a nanoemulsion having fine particles.
The transparent microemulsion according to an embodiment of the present invention is prepared by mixing 12 to 25% by weight of the mixed surfactant obtained in Example 2 with 50 to 85% by weight of cetyl ethylhexanoate (oil phase) and 0.1 to 5% by weight of the mixed surfactant obtained in Example 2. As a representative example, when 20% by weight of the mixed surfactant, 78% by weight of cetyl ethylhexanoate (oil phase), and 2% by weight of purified water (aqueous phase) are mixed, a transparent microemulsion is formed by simple stirring.
The transparent microemulsion is a composition prepared by mixing the mixed surfactant of each of Examples 1 to 7 with cetyl ethylhexanoate (oil phase) and purified water, and may be used for skin toner, lotions, emulsions, essences, or creams to obtain any one of effects of facilitating percutaneous absorption, providing moisturizing activity, supplying nutrition, adjusting pH, controlling skin oil-moisture balance, alleviating fine wrinkles, and improving whitening and lifting activity.
Here, the oil phase may be oil such as cetyl ethylhexanoate, ethylhexyl palmitate, squalane, polydecene, capric/caprylic triglyceride, macadamia oil, apricot oil, argan oil, or camellia oil, but is not particularly limited thereto.
The method of preparing the cosmetic composition according to an embodiment of the present invention includes mixing a mixed surfactant with an oil, dissolving the mixed surfactant in the oil while heating at 68 to 85° C., and adding purified water to the result, followed by stirring at 700 to 4,000 rpm for 2 to 8 minutes to prepare a transparent microemulsion.
The technical feature of the present invention is that the transparent microemulsion can be prepared by simple stirring at 700 to 4,000 rpm without using a certain high-pressure microfluidizer.
It is important to mix the mixed surfactant prepared by mixing sucrose distearate with polyglyceryl-10 oleate, which are components according to an embodiment of the present invention, at a predetermined ratio so that a lamellar continuous structure can be stably formed. When a mixed system of the mixed surfactant with an oil reacts with purified water, it should be arranged linearly by hydrogen bonding and should have interfacial association to form a self-organized continuous structure.
Therefore, the combinations of mixed surfactants obtained according to the present invention can be easily arranged to form a continuous structure when mixed with various oils and to maintain thermodynamic stability.
Meanwhile, cetyl ethylhexanoate selected herein is an example of a non-polar oil with low polarity. The cetyl ethylhexanoate is selected because it can form a continuous lamellar structure well within the alkyl chain of the surfactant and thus is highly compatible with the mixed surfactant developed in the present invention.
In the present invention, the region of the ternary component system where a transparent microemulsion is formed and other regions where interfacial chemical structures are formed are shown in
As shown in
In addition, the lamellar crystal structure formed in the liquid crystal region (LC) is provided as a paste-like gel including micelles arranged in continuous multiple layers on a flat plate and such a flat lamellar gel structure is generally referred to as a “lamellar crystal (liquid crystal) structure”. The cubic phase formed in the cubic region (Q1) has a square cubic structure. In addition, the hexagonal phase formed in the hexagonal region (H) has a hexagonal cylinder structure. Depending on the composition ratio of the ternary components, a variety of structures such as an oil-in-water O/W emulsion phase, a water-in-oil type W/O emulsion phase, a reverse micelle phase, a surfactant phase, a combination of a reverse micelle and a water-in-oil (W/O) emulsion phase, and a combination of a hexagonal phase and an O/W emulsion phase are formed.
Meanwhile, various conditions for preparing transparent microemulsions based on the mixed surfactant of Example 2 are shown in Examples 8 to 13 of Table 2. As can be seen from Examples 8 to 13, a transparent microemulsion is formed using 5 to 30% by weight of the mixed surfactant, 67.8 to 92.8% by weight of cetyl ethylhexanoate (oil phase), and 0.1 to 8% by weight of purified water (aqueous phase). The transparent microemulsion was a transparent liquid with a pH of about 6.12 to about 6.51. It can be seen that the specific gravity of the final product was in the range of 0.950 to 1.000. All the final products were stable after 4 weeks at 45° C.
The additives in the composition in Table 2 above are substances that exhibit effects on the skin during the skin effect test on the formulation of the present invention. Therefore, these additives are components that do not affect the preparation of the microemulsion or nanoemulsion structure of the present invention.
Meanwhile,
Meanwhile,
In this example, a fine nanoemulsion was prepared using the mixed surfactant of the present invention with the composition shown in Table 3 below. The present example is a method of preparing a fine nanoemulsion. A lotion or ampoule essence prepared from the fine nanoemulsion has advantages of appearance suitable for blue light depending on the particle size, excellent skin absorption, and superior texture.
As described above, a fine nanoemulsion can be prepared from the mixed surfactant prepared in the present invention without using a special high-pressure microfluidizer. In particular, it is a remarkable feature of the present invention that the preparation of a fine nanoemulsion with the characteristics was completed using a surfactant composition containing no polyethylene glycol (PEG). In particular, the innovative feature of the present invention is to use a mixed surfactant of the sucrose distearate and polyglyceryl-10 oleate.
The emulsion using 3 to 11% by weight of polysorbate 60 as a conventional surfactant and 5 to 30% by weight of an oil phase is usually milky white and has a particle size of about 8.560 μm. In addition, when a liposome emulsion containing 3 to 11% by weight of hydrogenated lecithin, which forms conventional liposomes, and 5 to 30% by weight of the oil phase was allowed to pass through a high pressure microfluidizer (10,000 psi, 50° C., 3 times), a milky white emulsion with a particle size of 826.72 nm was obtained. On the other hand, in Example 19 of the present invention, fine nanoparticles with a size of 72.95 nm were formed, which is a feature distinctive from the prior art. This particle size may be much smaller when taking into consideration the fact that liposomes, which are usually formed by passing through a microfluidizer 2 to 6 times, have a size of 200 to 950 nm.
In this experiment, samples were prepared and skin efficacy was tested as shown in Table 4 below.
Skin absorption, skin moisturizing, and fine wrinkle alleviation effects of Comparative Examples 1 and 2 and Example 19 (Fine nanoemulsion) were tested. Comparative Example 1 is a general O/W emulsion and Comparative Example 2 is a general liposome. Example 19 is a fine nanoemulsion of the present invention. The effects of the present invention could be confirmed by comparison therebetween.
Percutaneous absorption of Comparative Examples 1 and 2, and Example 19 (fine nanoemulsion) was measured.
Percutaneous absorption was tested by tape stripping using AHK-Cu peptide as an indicator. The sample for testing percutaneous absorption contains 1,000 ppm of AHK-Cu peptide as in Example 19. The test method is as follows. A square with a width of 1 cm and a length of 1 cm was drawn on the lower forearm and 0.1 mg of the sample was applied thereto twice every 5 minutes. After 8 hours, an exfoliation tape was stripped in the applied area 9 times, stored separately, was further stripped therein 10 to 15 times and quantitatively analyzed by HPLC.
The results are shown in the graph of
It was found that the fine nanoemulsion of Example 19 had at least 14.6 times higher percutaneous absorption than Comparative Example 1 and at least 1.43 times higher than Comparative Example 2. These results showed that Example 19 exhibited much better percutaneous absorption than Comparative Examples 1 and 2. The reason for this is that the fine nanoemulsion of the present invention has a much finer particle size than both of Comparative Examples and is absorbed in a higher amount quickly. In addition, another reason is that a fine nanoemulsion can be prepared without passage through a high-pressure microfluidizer.
The skin moisturizing effect of Comparative Examples 1 and 2, and Example 19 (fine nanoemulsion) was measured.
The moisturizing effect test was conducted on 6 subjects (in their 20s to 60s, male and female), measurement was performed 3 times and the average of the measured values was obtained. A predetermined amount (2 g) of each sample was applied to the face twice a day (morning and evening) over 4 weeks and the moisture content of a specific spot of the skin was measured using a moisture meter in an incubator unaffected by humidity. The results of measurement only after 4 weeks are shown.
The results are shown in
The fine wrinkle alleviation effect of the fine nanoemulsion of the present invention based on fast percutaneous absorption was clinically tested. The effect of alleviating skin fine wrinkles of Example 19 and Comparative Examples 1 and 2 was tested.
The test was performed using a skin wrinkle meter from Aramo TS (Korea). A predetermined amount (2 g) of each sample was applied to the entire face twice a day (morning and evening) over 4 weeks, and the alleviation of skin fine wrinkles was measured numerically in the certain spot around the eyes (around the eyebrows, where fine wrinkles are most common) after 4 weeks. The skin fine wrinkles were measured three times on 12 subjects for each sample and a final score was determined using the average of the three measured values.
The results of measurement of the effect of alleviating fine wrinkles around the eyes are shown in
2% of niacinamide as a generally known whitening component was added to the fine nanoemulsion of the present invention to prepare a fine nanoemulsion of Example 20 and then whitening effect thereof was measured.
The fine nanoemulsion (Example 20), a general O/W emulsion (Comparative Example 3), and a general liposome (Comparative Example 4) contained the same concentration of whitening component and the whitening performance was tested in-vivo clinically under the same conditions (Table 5).
The test was performed using a measuring device from Aramo TS (Korea) quantifying the degree to which the skin is clear and calculating the reduction effect of melanin deposited on the skin. In-vivo clinical evaluation was performed as follows. A predetermined amount of each sample was applied to the entire face twice a day (morning and evening) over 4 weeks, and the skin whitening effect was quantified in the certain spot areas on the face after 4 weeks. The skin whitening effect was measured three times on 12 subjects for each sample and a final score was determined using the average of the three measured values.
The results of measurement are shown in
An in-vivo experiment to improve skin lifting effect was performed using Example 19 and Comparative Examples 1 and 2.
The test was performed using a skin lifting meter from Aramo TS (Korea). Skin lifting evaluation was performed as follows. A predetermined amount of each sample was applied to the entire face twice a day (morning and evening) over 4 weeks, and the skin lifting effect after 4 weeks was measured in the certain area on the face. The skin lifting effect was measured three times on 10 subjects for each sample and a final score was determined using the average of the three measured values.
The results of lifting measurement are shown in
A skin pH improvement effect of Example 19, Example 20, and Comparative Examples 1 and 2 was tested.
The test was performed using a skin pH meter from Aramo TS (Korea). Skin lifting test was performed as follows. A predetermined amount of each sample was applied to the entire face twice a day (morning and evening) over 4 weeks, and the pH was measured on the face after 4 weeks. The skin pH was measured three times on 10 subjects for each sample and a final score was determined using the average of the three measured values.
The results of measurement are shown in
As described above, the microemulsion according to present invention is quickly absorbed into the skin, and exhibits excellent skin improvement effects such as moisturizing, fine wrinkle alleviation, whitening and lifting improvement and pH improvement.
It would be obvious that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims. Therefore, the scope of the present invention is not limited by the examples described above and is defined only by the claims and equivalents thereto.
Several types of cosmetic compositions according to examples will be illustrated and the present invention is not limited thereto.
As is apparent from the foregoing, the present invention provides a surfactant mixture of high-purity sucrose fatty acid ester and polyglyceryl-10 fatty acid ester as surfactants. A transparent microemulsion can be prepared by only simple stirring the ternary component system formed by adding an oil and purified water to the surfactant mixture. In addition, a nanoemulsion can be prepared therefrom under simple conditions.
The present invention is applicable to skin toners, lotions, creams, essences, ampoules, or mask sheets in cosmetics and can be absorbed quickly in the skin and exhibits excellent skin improvement effects such as moisturizing, fine wrinkle alleviation, whitening and lifting improvement and pH improvement.
Although the preferred embodiments of the present invention have been disclosed for illustrative purposes, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10-2023-0116230 | Sep 2023 | KR | national |
