A rhamnolipid self-emulsifying skin care emulsion, preparation method and application

Abstract

The application discloses a rhamnolipid self-emulsified skin care emulsion, a preparation method and application, and specifically discloses application of rhamnolipid in maintaining skin pH, skin moisturizing or penetration promotion, and discloses a rhamnolipid self-emulsified skin care emulsion, raw materials of which include a water phase and an oil phase, the water phase can contain acid or alkali, and the mass ratio of rhamnolipid in the skin care emulsion is greater than or equal to 0.2%; and the pH value of the skin care emulsion is 5.0-6.0. The skin care emulsion has the advantages of high moisturizing property, high stability, high penetration capacity and long-acting maintenance of skin pH.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of skin care emulsion, in particular to a rhamnolipid self-emulsified skin care emulsion, a preparation method and application thereof. BACKGROUND

[0002] As a kind of biosurfactant synthesized by microorganism, rhamnolipid has the advantages of green safety, environmental friendliness, mildness and high activity. Rhamnolipid is a kind of biosurfactant with the longest research time and the most mature application technology.

[0003] As one of the important means for microorganisms to uptake nutrients from the natural environment, rhamnolipid has a chemical structure similar to that of cell membrane phospholipids, and can form micelles that can easily penetrate the cell membrane for material delivery. Rhamnolipid has both hydrophilic sugar rings and lipophilic carbon chains in its chemical structure, and can easily spread on the skin surface to form a liquid film after being made into a uniform dispersion system, thereby exerting its amphiphilic activity. In summary, it is not difficult to find that rhamnolipid also has the significance of being used as a skin care emulsifier and a penetration enhancer.

[0004] However, at present, in the field of personal care products, rhamnolipid is usually used as a surfactant for body cleaning, and there are terminal products such as shampoo and cleansing mousse containing rhamnolipid on the market.

[0005] However, as a cleaning surfactant, skin care emulsifier and penetration enhancer, the performance advantages of rhamnolipid are not fully utilized. SUMMARY

[0006] The technical problem to be solved by the present application is to further expand the performance advantages of rhamnolipid by providing a rhamnolipid self-emulsified skin care emulsion, a preparation method and application thereof.

[0007] Application of rhamnolipid in maintaining skin pH.

[0008] The rhamnolipid also includes the application in skin moisturizing and / or penetration promotion, and the rhamnolipid is mainly of Rha-Rha-C10-C10 type, and the mass fraction of Rha-Rha-C10-C10 type in the rhamnolipid is 40% or more.

[0009] Firstly, the present application provides the application of rhamnolipid in maintaining skin pH, i.e. the rhamnolipid has the effect of maintaining skin pH when applied in skin care emulsion.

[0010] Secondly, the application provides application of rhamnolipid in skin moisturizing, namely, the rhamnolipid has the effect of skin moisturizing when applied in skin care lotion, and when the rhamnolipid is mainly Rha-Rha-C10-C10 type rhamnolipid and the mass ratio of Rha-Rha-C10-C10 type in the rhamnolipid is 40% or above, the skin moisturizing function of the skin care lotion can be further improved.

[0011] Furthermore, the application provides application of rhamnolipid in penetration promotion, namely, the rhamnolipid has the effect of penetration promotion when applied in skin care lotion, and when the rhamnolipid is mainly Rha-Rha-C10-C10 type rhamnolipid and the mass ratio of Rha-Rha-C10-C10 type in the rhamnolipid is 40% or above, the penetration promotion function of the skin care lotion can be further improved.

[0012] The application further provides a rhamnolipid self-emulsified skin care lotion, raw materials of which include water phase and oil phase, the water phase can contain acid or alkali, the mass ratio of the rhamnolipid in the skin care lotion is greater than or equal to 0.2%, and the pH value of the skin care lotion is 5.0-6.0.

[0013] The rhamnolipid contains four common configurations: Rha-C10, Rha-C10-C10, Rha-Rha-C10 and Rha-Rha-C10-C10, and in addition, Rha-Rha-C8-C10, Rha-C8-C10, Rha-Rha-C10-C12, Rha-C10-C12, Rha-Rha-C10-C12:1 and Rha-C10-C12:1 are allowed to have special structures, and the rhamnolipid in the application is preferably rhamnolipid mainly composed of Rha-Rha-C10-C10 type, and the mass ratio of Rha-Rha-C10-C10 type rhamnolipid in the rhamnolipid is greater than or equal to 40%, preferably 50%-99%.

[0014] In the application, the mass ratio of the oil phase and the rhamnolipid in the skin care lotion is 2%-80%, preferably 5%-40%, and the mass ratio of the water phase in the skin care lotion is 20%-98%, preferably 60%-95%. The oil phase can simultaneously contain one, more or all of various types of oils, and preferably contains at least one of ester, hydrocarbon oil, natural oil, alkanol, fatty acid and silicone oil.

[0015] The ester includes at least one of triglyceride and monoester, diester, polyester and other esters except triglyceride; the triglyceride preferably includes at least one of octanoic acid / capric acid triglyceride (GTCC), C10-C18 fatty acid triglyceride, triheptanoin, tribehenin and other chemical substances obtained by esterification of fatty acid and glycerol; the monoester, diester, polyester and other esters except triglyceride preferably include isononyl isononanoate, isopropyl myristate, ethylhexyl palmitate, dibutyl adipate, ester wax, diisostearyl malate, triisostearyl citrate, pentaerythritol tetra stearate and other emollient oils containing one or more ester groups.

[0016] The hydrocarbon oil preferably includes at least one of squalane, squalene, white oil, hydrocarbon wax, hydrogenated polyisobutylene, isododecane, isohexadecane and other hydrocarbon skin care oils containing only carbon and hydrogen.

[0017] The natural oil includes oils extracted from various animal and plant products and minerals, and is generally a mixture of organic oils with various chemical structures, and preferably includes at least one of white pool seed oil, jojoba oil, sweet almond oil, camellia oil, coconut oil, macadamia nut oil, avocado oil, shea butter, cocoa butter, mango butter, grape seed oil, marula oil, rose oil, sunflower seed oil, wild soybean oil, beeswax, ozokerite, carnauba wax, candelilla wax and other natural oils.

[0018] The alkanol preferably includes at least one of cetyl stearyl alcohol, behenyl alcohol, lauryl alcohol, myristyl alcohol, arachidyl alcohol, melissyl alcohol and other higher aliphatic alcohols with 12 or more carbon atoms.

[0019] The fatty acid preferably includes at least one of stearic acid, palmitic acid, myristic acid and other higher aliphatic acids with 12 or more carbon atoms.

[0020] The silicone oil preferably includes at least one of cyclotetrasiloxane, 6-viscosity silicone oil, 100-viscosity silicone oil, 350-viscosity silicone oil, phenyl silicone oil, octyl silicone oil, silicone elastomer and other modified products of dimethyl silicone obtained by grafting, block and cross-linking.

[0021] As one of the embodiments, the water phase includes water, preservative, acid or base, and preferably includes at least one of humectant, thickening agent, emulsifier and other components.

[0022] The water used in the present application means a large-dose liquid used as a solvent and dispersion medium, and preferably includes deionized water, purified mineral water, purified seawater, plant tissue liquid (such as sponge gourd water, bamboo juice, white birch juice and other liquids with water as the main component) and fermentation filtrate.

[0023] The preservative mainly comprises a kind of compound capable of inhibiting microbial activity, effectively delaying emulsion system spoilage;For example: the preservative includes at least one of organic acid, nipagin ester, formaldehyde release body and alcohol, preferably at least one of phenoxy ethanol, sodium benzoate, potassium sorbate, hexanediol, p-hydroxyacetophenone, octanol, octanoyl hydroxamic acid, pentanediol, nipagin methyl ester, nipagin ethyl ester, ethyl hexyl glycerol and the like;

[0024] The base of the application is an inorganic or organic compound that makes the pH of the solution alkaline after being dissolved in water, which can neutralize the carboxyl in the unneutralized rhamnolipid structure, and preferably includes at least one of potassium hydroxide, sodium hydroxide, triethanolamine, aminomethyl propanol, arginine, ammonia and the like;The acid of the application is an inorganic or organic compound that makes the pH of the solution acidic after being dissolved in water, which can be acidified to generate carboxyl with the carboxylate ion in the rhamnolipid structure, and preferably includes at least one of citric acid, lactic acid, fruit acid, salicylic acid and the like.

[0025] The humectant of the application mainly includes cosmetic raw materials that can produce affinity with water, increase and maintain skin moisture in a relatively wide humidity range and for a long time;For example: the humectant preferably includes at least one of polyhydric alcohol, polysaccharide, polyethylene glycol, natural factor, and more preferably at least one of glycerol, propylene glycol, butanediol, pentanediol, isopentanediol, hexanediol, sorbitol, xylitol, hyaluronic acid, sodium hyaluronate, fructooligosaccharide, trehalose, polyethylene glycol, sodium lactate, amino acid, betaine, pyrrolidone carboxylic acid and its salt, urea and the like;

[0026] The thickening agent of the application mainly includes high molecular polymer substances that can associate with water, expand in volume, intertwine with molecular chains and the like after being dispersed in water, finally resulting in significant increase in viscosity of water body and change in rheological properties;For example: the thickening agent includes at least one of polyacrylic acid, polysaccharide, polyurethane, natural gum, polyoxyethylene, and preferably at least one of carbomer, acryloyldimethyl ammonium taurate / VP copolymer, hydroxyethyl acrylate / sodium acryloyldimethyl taurate copolymer, acrylate / C10-30 alkyl acrylate crosslinked copolymer, polyacryloyl dimethyl ammonium taurate, xanthan gum, sodium alginate, guar gum, sodium polyacrylate, sodium polyacrylate grafted starch, gellan gum, cellulose, polyacrylate crosslinked polymer-6 and the like.

[0027] The application also provides a preparation method of the above-mentioned skin care emulsion, including direct self-emulsification method and dispersion self-emulsification method;Direct emulsification method is suitable for rhamnolipid in all forms and pH conditions, and dispersion self-emulsification method is mainly suitable for pure acid rhamnolipid.

[0028] The direct self-emulsifying method comprises: obtaining an acid or alkali containing water phase composition; obtaining an oil phase composition; obtaining a skin care emulsion by adding the acid or alkali containing water phase composition into the oil phase composition; and adding the rhamnolipid into any step of the obtaining of the water phase, the obtaining of the oil phase or the obtaining of the skin care emulsion. The rhamnolipid includes neutralized rhamnolipid and unneutralized rhamnolipid. The neutralized rhamnolipid has better hydrophilicity, and the unneutralized rhamnolipid has better lipophilicity. Preferably, the unneutralized rhamnolipid is added into the step of the obtaining of the oil phase, and the neutralized rhamnolipid is added into the step of the obtaining of the water phase.

[0029] As a specific implementation, the process is as follows: the oil phase composition containing the rhamnolipid is heated to 70-95°C, preferably 80-85°C. After the oil phase composition is heated, melted and mixed into a uniform liquid or turbid gel, the acid or alkali containing water phase composition at the same temperature is added dropwise into the hot oil phase composition under the condition of stirring at 100-700rpm or homogenizer running at 3000-10000rpm, preferably stirring at 300-500rpm or homogenizer running at 5000-8000rpm. It can be observed that the system gradually changes from a liquid or turbid gel into a whitish emulsion after the water phase composition is added into the system. Depending on the composition of the oil and water phases, there may be a significant phase inversion phenomenon. That is, the system is a water-in-oil emulsion when the water phase is initially added, and the two phases are reversed when the water reaches a certain amount, the water migrates into the outer continuous phase, and the oil phase becomes the inner dispersed phase. The system becomes an oil-in-water emulsion. The emulsion is kept at about 60-70°C for 10-30min after the emulsion is formed, preferably at about 60-65°C for 20-30min, and the stirring speed is 100-700rpm, preferably 200-300rpm. Then the temperature is gradually lowered to room temperature, and the stirring is stopped to obtain the rhamnolipid self-emulsifying skin care emulsion. It should be noted that when the direct (neutralized) emulsification method is used to prepare the rhamnolipid self-emulsifying skin care emulsion, the temperature of the water and oil phases should be consistent, or the temperature of the water phase should be slightly higher than that of the oil phase. Otherwise, the oil phase may coagulate due to cooling, resulting in neutralization difficulty and unsatisfactory emulsification effect.

[0030] In the above preparation process, the rhamnolipid is preheated and mixed with other oil phase compositions, the heating temperature is 70-95°C, preferably 80-85°C; after uniform heating and mixing, the acid or base is directly added into the water phase composition; under the conditions of stirring at 100-500 rpm or homogenization at 3000-10000 rpm, the water phase is gradually added into the oil phase when the temperature of the water phase is the same as or slightly higher than that of the oil phase; depending on the different formula composition, there may be a significant and observable phase inversion process; after the phase inversion is completed, the mixture is kept at 60-70°C and stirred for 10-30 min at a stirring speed of 100-700 rpm.

[0031] The dispersion and self-emulsification method comprises: water phase acquisition, preparation of an acid-free and base-free water phase composition; oil phase acquisition, preparation of an oil phase composition; skin care emulsion acquisition, mixing the acid-free and base-free water phase composition and the oil phase composition to obtain an oil-water mixture, adding an acid or a base into the oil-water mixture to obtain the skin care emulsion; the rhamnolipid can be added into any step of the water phase acquisition, the oil phase acquisition or the skin care emulsion acquisition; the rhamnolipid includes neutralized rhamnolipid and unneutralized rhamnolipid; the neutralized rhamnolipid has better hydrophilicity, and the unneutralized rhamnolipid has better lipophilicity; preferably, the unneutralized rhamnolipid is added into the step of the oil phase acquisition, and the neutralized rhamnolipid is added into the step of the water phase acquisition.

[0032] As a specific implementation, the process is as follows: the oil phase composition containing rhamnolipid and the acid-free and alkali aqueous phase composition are heated to 70-95℃, preferably 80-85℃, respectively, and after the oil phase composition is heated and melted to be mixed into a uniform liquid state, the water-oil two-phase temperature is kept the same or the aqueous phase temperature is slightly higher than the oil phase temperature, and then the water-oil two phases are mixed, the stirring speed is 100-700 rpm, preferably 300-500 rpm, or the homogenization speed is 3000-10000 rpm, preferably 5000-8000 rpm; under the running state of the stirring paddle or homogenizer, the water-oil two phases are directly stirred into a dispersion in which the oil phase is dispersed in the aqueous phase in the form of extremely small droplets. The stirring or homogenization condition is kept unchanged, and a proper amount of acid or alkali calculated is added, and the mixture is kept at 60-70℃ for 10-30 min, preferably 60-65℃ for 20-30 min, the stirring speed is 100-700 rpm, preferably 200-300 rpm; after stirring, the temperature is gradually reduced to room temperature, and the stirring is stopped to obtain the rhamnolipid self-emulsifying skin care emulsion. It should be noted that if the oil and water two phases are difficult to be uniformly dispersed under the stirring or homogenization condition due to the difference in composition, a small amount of emulsifier commonly used in cosmetics, such as monoglyceride, PEG, polyglycerol, glycoside, polysorbate and sorbitan, is added in the formula, accounting for 0.05%-0.5% of the entire formula system, preferably 0.2%-0.3%, which cannot stably emulsify all oil phase compositions, but only plays an auxiliary dispersion role.

[0033] In the above preparation process, the rhamnolipid and other oil phase compositions are preheated, melted and mixed uniformly; the acid and alkali substances are not directly mixed with the aqueous phase composition, but are added into the system after the oil and water are dispersed; the water and oil two phases are mixed under the condition that the stirring speed is 100-500 rpm or the homogenization speed is 3000-10000 rpm, the water and oil two phases have the same temperature, or the aqueous phase temperature is slightly higher than the oil phase temperature; the mixture is kept at 60-70℃ for 10-30 min, and the stirring speed is 100-700 rpm; there is no phase inversion process, and if the oil phase is difficult to disperse, 0.05%-0.5% of emulsifier is added to assist dispersion.

[0034] In the above two preparation methods, the addition of acid or alkali preferably makes the pH range of the emulsion system be 5.0-6.0. In this pH range, part of the carboxyl groups in the rhamnolipid are neutralized into ions, and the other part remains as carboxyl groups. The neutralized rhamnolipid has high surface activity, and the unneutralized rhamnolipid is lipophilic. The ionized rhamnolipid emulsifies the unneutralized rhamnolipid and other oily ingredients into an emulsion, so this kind of emulsion is called rhamnolipid self-emulsifying emulsion.

[0035] The technical scheme of the present application has the following advantages:

[0036] 1. When the rhamnolipin provided by this invention is applied to skin care lotion, it can not only achieve the emulsification effect already disclosed by rhamnolipin itself, but also achieve the effect of maintaining the skin's pH balance for a long time, which has the advantage of effectively expanding the performance of rhamnolipin; and it can also effectively maintain good skin moisturizing and penetration promotion effects.

[0037] 2. The present invention provides a rhamnolipin self-emulsifying skin lotion, which uses rhamnolipin as an emulsifier and controls the mass ratio of rhamnolipin in the skin lotion to be ≥0.2%. Under this formula, the skin lotion has the effects of high moisturizing, high stable emulsification, high penetration promotion, and long-lasting maintenance of skin pH.

[0038] The mechanism by which this invention achieves the above-mentioned effects of high moisturizing, stable emulsification, high penetration enhancement, and long-lasting maintenance of skin pH may be as follows:

[0039] Stable emulsion: Before being neutralized by alkali, the carboxyl group attached to the end of the carbon chain in the chemical structure of rhamnolipid exists stably as a nonionic group. However, it can undergo anionic-nonionic structural transformation under different pH conditions. That is, when unneutralized rhamnolipid encounters alkaline substances, the carboxyl group will be neutralized and ionized to generate rhamnolipid salts. At this time, rhamnolipid exhibits high surface activity and has strong cleaning ability and emulsion stabilization ability. This characteristic of rhamnolipid can be used to adjust the surface activity of rhamnolipid and the stability of colloidal system.

[0040] High penetration enhancement: As one of the important means for microorganisms to obtain nutrients from the natural environment, rhamnolipin has a chemical structure that is very similar to cell membrane phospholipids. It can be constructed into micelles that can easily pass through the cell membrane for substance delivery. Taking advantage of this characteristic of rhamnolipin, it can be used as a penetration enhancer in skin care products to improve the penetration effect, thereby increasing the transdermal absorption rate of the functional ingredients it carries, thus achieving a more efficient skin care effect.

[0041] High moisturizing effect: Rhamnolipids have both hydrophilic sugar rings and lipophilic carbon chains in their chemical structure. After being made into a uniform dispersion system, they can be easily spread on the skin surface to form a liquid film and exert their amphiphilic activity. Utilizing this special structure, rhamnolipids can not only reduce the evaporation of water from the skin surface, but also have an affinity for water molecules, effectively increasing the moisture content of the skin surface and achieving a high moisturizing effect.

[0042] Long-acting maintenance of skin pH: the carboxyl group in the chemical structure of rhamnolipid is partially neutralized into ions under the action of an appropriate amount of base, so that it has emulsification stability; and, due to the pH buffering effect of rhamnolipid, when the pH of the emulsion system is adjusted to between 5.0-6.0, the pH value of the area of the skin where the emulsion is applied is maintained in a stable numerical interval that matches the acid-base condition of healthy skin, ensuring the skin's acid-base degree when applying; at the same time, through verification, the use of rhamnolipid can also effectively maintain the skin's acid-base degree in the appropriate range for a long time, with remarkable effect. BRIEF DESCRIPTION OF DRAWINGS

[0043] In order to more clearly illustrate the specific embodiments of the present application or the technical solutions in the prior art, the drawings needed in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present application, and those skilled in the art can also obtain other drawings according to these drawings without creative labor.

[0044] Figure 1 It is a chemical structure diagram of Rha-Rha-C10-C10 type rhamnolipid in Example 1 of the present application, including the structure before and after neutralization (the alkaline substance used for neutralization is taken as potassium hydroxide as an example), a is the structure before neutralization, and b is the structure after neutralization;

[0045] Figure 2 It is a real object diagram of the skin care emulsion prepared in Example 1 of the present application. DETAILED DESCRIPTION

[0046] The following examples are provided to better further understand the present application and are not limited to the best mode, and do not constitute a limitation on the content and scope of protection of the present application. Any person under the inspiration of the present application or the combination of the present application with other prior art features can obtain any product identical or similar to the present application, which falls within the protection scope of the present application.

[0047] The specific experimental steps or conditions not mentioned in the examples can be carried out according to the conventional experimental steps described in the literature in the art or the operation or conditions. The reagents or instruments not mentioned by the manufacturer are conventional reagent products that can be obtained by market purchase.

[0048] The raw materials used in the following examples and comparative examples are as follows:

[0049] Rhamnolipid, 1,3-butylene glycol, Carbomer from Wanhua Chemical; isopentyldiol from KOEL; AVC from Clariant; glycerin, cetostearyl alcohol from Procter & Gamble; nicotinamide from DSM-Phenomine; shea butter, phenoxyethanol, caprylic / capric triglyceride from BASF; triheptanoin from Eurolipid; p-hydroxyacetophenone, 1,2-hexanediol from Symrise; sodium benzoate from Merck; PHL from Indigo; squalane, isopropyl myristate, glyceryl stearate / PEG-100 glyceryl stearate (A165) from Dow Corning; ceramide 3, polyglyceryl-3 methylglucose distearate (TEGO Care 450) from Evonik; cholestanol from Koei; 100 viscous silicone oil from Dow Corning; Tween-80, methanol, arginine, isopropyl alcohol from Aldrich.

[0050] The units of the raw materials not marked with quality in the following table are kg, and the rhamnolipid is added in pure form.

[0051] Example 1

[0052] The raw material composition of the skin care emulsion is shown in Table 1.

[0053] Table 1

[0054]

[0055]

[0056] Note: 2R2C in the table is a short form of Rha-Rha-C10-C10, and the structure of Rha-Rha-C10-C10 is shown as Figure 1 30% 2R2C means that the mass percentage of the rhamnolipid with 2R2C structure in the total rhamnolipid is 30%, and the same applies below.

[0057] The preparation process of the above skin care emulsion is as follows:

[0058] 1. Prepare the water phase and oil phase compositions according to the solubility characteristics respectively;

[0059] 2. Heat the water phase and oil phase compositions to about 85°C in the same water bath pot;

[0060] 3. Keep the heating conditions unchanged, and open the stirring paddle to stir the oil phase at a speed of 500 rpm;

[0061] 4. Add the water phase under the same insulation condition drop by drop to the stirring oil phase, and the drop adding speed is about 60 d / s;

[0062] 5. After the water phase is completely added, keep the temperature at about 60°C and stir for 30 min;

[0063] 6. After cooling to room temperature, the product can be discharged to obtain a skin care emulsion as shown in Figure 2

[0064] Example 2

[0065] The skin care emulsion has the raw material composition shown in Table 2.

[0066] Table 2

[0067]

[0068] The preparation process of the above skin care emulsion is as follows:

[0069] 1. The water phase and oil phase compositions are prepared according to the solubility characteristics, but the alkali is not added to the water phase;

[0070] 2. The water phase and oil phase compositions without alkali are heated to about 85°C in the same water bath pot;

[0071] 3. The heating condition is kept unchanged, and the oil phase is stirred at a stirring speed of 500 rpm;

[0072] 4. The water phase under the same temperature condition is added dropwise into the stirring oil phase, and the dropwise adding speed is about 60 d / s;

[0073] 5. After cooling, the temperature is kept at about 60°C for 30 min, and the stirring speed is 300 rpm;

[0074] 6. After cooling to room temperature, the product can be discharged.

[0075] The skin care emulsion has the raw material composition shown in Table 3.

[0076] Table 3

[0077]

[0078]

[0079] The preparation process of the above skin care emulsion is as follows:

[0080] 1. The water phase and oil phase compositions are prepared according to the solubility characteristics;

[0081] 2. The water phase and oil phase compositions are heated to about 85°C in the same water bath pot;

[0082] 3. The heating condition is kept unchanged, and the oil phase is stirred at a stirring speed of 500 rpm;

[0083] 4. The water phase under the same temperature condition is added dropwise into the stirring oil phase, and the dropwise adding speed is about 60 d / s;

[0084] ​5. After the water phase is added completely, keep the temperature at about 60℃ and stir for 30min;

[0085] 6. After cooling to room temperature, the product can be discharged.

[0086] The preparation method and the formula components in the above examples 1-3 can be replaced to a certain extent, wherein the formula of example 1 can also be used for emulsion preparation by the process provided in example 2, and there is no strict corresponding relationship between the formula and the preparation process, and they can be used alternately, and the purpose of the present application can be achieved under the preparation process parameters disclosed in the present application.

[0087] The stability of the skin care emulsion in the above examples 1-3 is detected, wherein the appearance of the skin care emulsion of example 1-1 is as shown in Figure 2 The skin care emulsion of example 1-1 can keep emulsification stable without oiling and demulsification after being stored at 50℃ for three months, centrifuged at 5000rpm for 30min, and frozen and thawed for eight weeks; the pH range of the skin care emulsion of the present application is between 5.0-6.0, and the viscosity range is 500cps-80000cps. According to different requirements of the skin care emulsion in the present application, the corresponding active ingredients such as bisabalol, ikedoin, VC-IP, nicotinamide, 377, etc. can be selectively added in the water phase or the oil phase composition; when used, a proper amount is directly taken and uniformly applied on the human skin.

[0088] The skin care emulsion in the present application has the moisturizing effect of slowing down the water loss of human skin and improving the water content of human skin, has the effect of adjusting the acid-base environment of human skin and maintaining the stability of the acid-base environment of human skin for a considerable period of time, has a chemical structure similar to the phospholipid of biological cell membrane, and can promote the transdermal absorption and utility of other efficacy components wrapped by its micelles.

[0089] In order to verify the above effects, the following experimental examples are provided.

[0090] Experimental example 1-pH adjusting effect

[0091] The pH test probe of the German CK non-invasive skin function detector was used to determine the skin pH regulating effect of the sample emulsion. The subjects with poor skin condition were selected, and the epidermal pH value was determined in advance. The healthy epidermal pH value should be about 5, if the skin barrier is damaged, or the subject has dry skin, the epidermal pH value may be greater than 6, or even greater than 7; similarly, if the pH value is too low, such as 4, it may cause the skin to easily produce oil and acne, which is also an unhealthy skin condition. Select subjects with high or low pH values, for each subject, draw a corresponding number of 3 cm x 3 cm areas in the test area, and apply all the test samples prepared in the examples to each sample test area in duplicate, and the area without sample application is used as a blank control group. It is recommended to take the sample area as the cheeks, forehead, outside of the calf, and inside of the forearm, and the selection area is determined according to the body condition of each subject. After the subjects arrived, they first washed the test area with running water, then gently patted the washed area with a soft cotton washcloth, and repeated the patting action twice, without rubbing hard to avoid damaging the skin cuticle. After completing the washing, sit still for more than 30 minutes to slow down and stabilize the physiological activity of the body, mark the corresponding test area with a marker pen, and then use the transdermal water loss test probe and water content test probe of the non-invasive skin function detector to determine the values according to the above-mentioned method. The test values of baseline, 5 minutes and 120 minutes after product application were tested three times, and the average value of each sample was calculated. The subjects were required to stop using all cleaning and moisturizing products on their legs, including soap, lotion, sunscreen, insect repellent, etc. during the 3-day pre-conditioning period before the test; the subjects were allowed to gently remove the hair 3 days before the test and 24 hours after the measurement, but not to scratch the skin. Avoid exercise, drinking hot drinks or caffeinated beverages within 2 hours before each test, as these behaviors can affect the accuracy and reliability of the measurement results. Any activity that causes sweating is strictly prohibited. The temperature and relative humidity of the test site were controlled at 20°C ± 2°C and 50% ± 10%, respectively.

[0092] The test results of the above examples are shown in Table 4 below:

[0093] Table 4 Skin pH value regulating effect verification data

[0094]

[0095]

[0096] From the results of Table 4, it can be seen that the skin pH of the subjects deviating from the normal value is improved to different degrees after using the present application. This is not only related to the pH of the rhamnolipid self-emulsifying emulsion itself being 5.0-6.0, but more importantly, there are carboxyl groups and other groups in the structure of rhamnolipid, and rhamnolipid can be regarded as an organic acid substance, thus having a pH buffering effect, which is a particularly key point. Therefore, the rhamnolipid self-emulsifying skin care emulsion can maintain the skin pH value in a reasonable range for a relatively long period of time, and will not cause large fluctuations in pH after changes caused by internal and external factors. This property is not possessed by common non-ionic emulsifiers and emollients including A165 and Tween-80. Therefore, compared with conventional non-ionic emulsifiers and emollients, the emulsion prepared using rhamnolipid has the additional effects of skin pH adjustment and stability maintenance in addition to meeting the general stability and efficacy requirements. Rhamnolipid has very rich skin care effects and broad application prospects.

[0097] Experimental Example 2 - Moisturizing effect

[0098] The moisturizing effect of the sample emulsions of the examples was determined using the trans-epidermal water loss and water content test probes of the German CK non-invasive skin function detector. Qualified subjects were selected, and for each subject, a corresponding number of 3 cm x 3 cm areas were drawn on the test area. All the test samples prepared in the examples were applied to the respective test areas in duplicate, and the areas without sample application served as the blank control group. It is recommended to select the sample area as the cheeks, forehead, outer side of the calf, and inner side of the forearm according to the body condition of each subject. After the subjects arrived, they first washed the test area with flowing clean water, then gently patted the washed area dry with a soft cotton washcloth, and repeated the patting action twice. Do not rub hard to avoid damaging the skin cuticle. After completing the washing, sit still for more than 30 minutes to slow down and stabilize the physiological activity of the body. Mark the test area with a marker pen, then use the trans-epidermal water loss test probe and water content test probe of the non-invasive skin function detector to determine the values according to the above-mentioned method. Test the values at baseline, 5 minutes and 120 minutes after application of the product, and take the average of the test values for each sample. The subjects were required to stop using all cleaning and moisturizing products on the legs, including soap, emulsion, sunscreen, insect repellent, etc., during the 3-day pre-conditioning period before the test. The subjects were allowed to gently remove the hair 2 hours before each test and 24 hours after the measurement, but were not allowed to scratch the skin. Avoid exercise, drinking hot drinks or beverages containing caffeine within 2 hours before each test, as these behaviors can affect the accuracy and reliability of the measurement results. Any activity that causes sweating is strictly prohibited. The temperature and relative humidity of the test site were controlled at 20°C ± 2°C and 50% ± 10%, respectively.

[0099] The test results of the above examples are shown in Tables 5 and 6 below:

[0100] Table 5 Transdermal water loss verification data

[0101]

[0102]

[0103]

[0104] Table 6 Epidermal water content verification data

[0105]

[0106]

[0107] From the results of Tables 5 and 6, it can be seen that the rhamnolipid self- emulsifying skin care emulsion of the present application can more significantly reduce the transdermal water loss and increase the epidermal water content of the skin than the skin care emulsion prepared using A165 and Tween-80 as emulsifiers. This is because the lipophilic carbon chain structure in the structure of rhamnolipid makes it easy to form a film and form a complete protective layer after being applied to the epidermis, and the hydrophilic sugar ring and carboxyl end in the structure have the effect of absorbing and associating water, which can keep the skin with sufficient moisture for a long time. While the carbon chain and hydrophilic chain in the structure of A165 and Tween-80 also have the dual effects of lipophilicity and hydrophilicity, the moisturizing and water-locking effects are not as good as those of rhamnolipid. Moreover, rhamnolipid can not only be used as a self-emulsifying emulsifier in the formula, but also as an emollient, and its use amount can be larger than that of A165, so its moisturizing effect is more obvious. As can be seen from the measured data in the table, when the amount of 2R2C rhamnolipid in the formula increases, such as in Examples 1-1 to 1-4, the transdermal water loss value of the skin after using the corresponding emulsion is also smaller, and the epidermal water content is also increased, indicating that the moisturizing effect of rhamnolipid is positively correlated with the content of 2R2C rhamnolipid. Therefore, rhamnolipid with a 2R2C configuration content higher than 40% has a more significant moisturizing and water-locking effect than rhamnolipid self-emulsifying emulsion with a 2R2C configuration content lower than 40% due to the higher proportion of hydrophilic sugar rings.

[0108] In addition, it is worth mentioning that most of the subjects said that the skin feel of the rhamnolipid self-emulsifying emulsion is significantly more refreshing than that of A165 and Tween-80 emulsion, because the aggregation state of rhamnolipid is a soft paste, and after neutralization, it becomes a low-viscosity fluid with good water solubility. Compared with A165 and Tween-80, the texture of rhamnolipid is more low-viscosity and light, which can provide a more light and comfortable skin feel, and will not cause skin suffocation, poor ventilation and excessive greasiness and acne. The water-soluble rhamnolipid on the skin surface can also gradually sweat and secrete oil with the human body, remove excessive secreted oil, control the oil coverage on the skin surface within a reasonable range, and thus provide a long-lasting refreshing feeling.

[0109] Experimental Example 3 - Penetration Effect

[0110] Take a piece of intact pigskin, clip the surface hair without damaging the stratum corneum, and remove the subcutaneous fat. The treated skin is thawed in PBS buffer for 20 min, and then cut into the required size (about 2.5 cm x 2.5 cm square). The side of the pigskin with the stratum corneum faces the donor chamber of the Franz diffusion cell. The receptor chamber of the Franz diffusion cell is filled with PBS buffer containing 5% Tween 80 by mass fraction. 1 g of skin care emulsion prepared with A165 as the emulsifier (Comparative Example 3) and 1 g of ceramide 3 skin care emulsion prepared by rhamnolipid self-emulsification (Example 3) are added to the donor chamber of different groups for testing the penetration of pigskin, with 3 parallel samples in each group. The receptor chamber is maintained at 37°C in a water bath for 12 h, and the stirring speed during diffusion is 300 r / min. After 12 h, the pigskin is taken out of the diffusion cell. The remaining sample is removed by washing and gently wiping the surface of the pigskin with absorbent cotton. After removing the stratum corneum of the pigskin, the pigskin is cut and soaked in an equal amount of methanol for ultrasonic extraction for 20 min. The content of ceramide 3 in the extract is detected by high performance liquid chromatography, and the chromatographic conditions are as follows: SHIMADZU Shim-pack VP-C18 ODS (150 mm x 4.6 mm, 5 μm) chromatographic column, C18 ODS guard column core, mobile phase V(methanol):V(isopropyl alcohol) = 55:45, flow rate 1.0 mL·min -1 , column temperature 30°C, ultraviolet detector detection, wavelength 205 nm, detection cell temperature 40°C. The detection results are shown in Table 7.

[0111] Table 7 - Penetration verification data

[0112]

[0113] From the data in Table 7, it can be seen that the rhamnolipid self- emulsifying skin care emulsion prepared according to the present application can better promote the penetration of ceramide 3 into the skin than the skin care emulsion prepared using A165 and Tween-80; and the rhamnolipid with a 2R2C configuration content of ≥40% has a significantly better penetration promoting effect than the rhamnolipid self-emulsifying emulsion with a 2R2C configuration content of <40%. This is because the chemical structure of rhamnolipid is very similar to the phospholipid structure of biological cell membranes, and can effectively deliver substances wrapped in the rhamnolipid micelles into cells, thereby promoting the transdermal absorption of the wrapped substances. Microorganisms in nature also use this property to secrete rhamnolipid as one of the important means for themselves to take in organic nutrients from the outside world. Using rhamnolipid as a penetration enhancer for active substances is a way of choosing in accordance with nature, and has its unique and positive application significance.

[0114] Obviously, the above embodiments are merely examples for the purpose of clarity and are not intended to limit the embodiments. Based on the above description, those skilled in the art can make other different forms of changes or modifications. All embodiments do not need to be exhausted here, and obvious changes or modifications derived therefrom are still within the protection scope of the present application.

Claims

1. Use of rhamnolipid in the preparation of skin care emulsion for long-term maintenance of skin pH.

2. Use according to claim 1, characterized in that, Also included in the application of skin moisturizing and / or penetration promotion, the rhamnolipid is mainly Rha-Rha-C10-C10 type rhamnolipid, the mass fraction of Rha-Rha-C10-C10 type in the rhamnolipid is 40% or more.

3. A rhamnolipid self-emulsifying skin care emulsion characterized in that, The raw materials include water phase and oil phase, the water phase contains acid or base, the mass fraction of rhamnolipid in the skin care emulsion is ≥0.2%; the pH value of the skin care emulsion is 5.0-6.0; the self-emulsifying skin care emulsion of rhamnolipid is used for long-term maintenance of skin pH.

4. The skin care emulsion of claim 3, wherein, The self-emulsifying skin care emulsion of rhamnolipid is also used for skin moisturizing and / or penetration promotion.

5. The skin care emulsion of claim 3, wherein, The oil phase further includes at least one of esters, hydrocarbon oils, natural oils, alkanols, fatty acids, and silicone oils; The water phase includes water, preservatives, and acid; The total mass fraction of the oil phase and rhamnolipid in the skin care emulsion is 2%-80%; The rhamnolipid is mainly Rha-Rha-C10-C10 type rhamnolipid, the mass fraction of Rha-Rha-C10-C10 type in the rhamnolipid is 40% or more.

6. The skin care emulsion of claim 5, wherein, The acid includes at least one of citric acid, lactic acid, fruit acid, and salicylic acid.

7. The skin care emulsion of claim 3, wherein, The water phase includes water, preservatives, and base.

8. The skin care emulsion of claim 7, wherein, The base includes at least one of potassium hydroxide, sodium hydroxide, triethanolamine, aminomethylpropanol, arginine, and ammonia.

9. The skin care emulsion of claim 5, wherein, The total mass fraction of the oil phase and rhamnolipid in the skin care emulsion is 5%-40%.

10. The skin care emulsion of claim 5, wherein, The esters include at least one of monoesters, diesters, and polyesters; The hydrocarbon oils include at least one of squalane, squalene, white oil, hydrocarbon wax, hydrogenated polyisobutylene, isododecane, and isohexadecane; The natural oils include at least one of white pool seed oil, jojoba oil, sweet almond oil, camellia oil, coconut oil, macadamia nut oil, avocado oil, shea butter, cocoa butter, mango butter, grape seed oil, marula oil, rose oil, sunflower seed oil, wild soybean oil, beeswax, ozokerite, carnauba wax, and candelilla wax; The alkanols are fatty alcohols with C12 or more; The fatty acids are fatty acids with C12 or more; The silicone oils include polydimethylsiloxane and its grafted, blocked, and crosslinked modifications.

11. The skin care emulsion of claim 10, wherein The esters include at least one of triglycerides, isononyl isononanoate, isopropyl myristate, ethylhexyl palmitate, dibutyl adipate, ester waxes, diisostearyl malate, triisostearyl citrate, and pentaerythrityl tetrahydroxystearate; The alkanols include at least one of cetearyl alcohol, behenyl alcohol, lauryl alcohol, myristyl alcohol, arachidyl alcohol, and melissyl alcohol; The fatty acids include at least one of stearic acid, palmitic acid, and myristic acid; The silicone oils include at least one of cyclopentasiloxane, 6 cSt silicone oil, 100 cSt silicone oil, 350 cSt silicone oil, phenyl silicone oil, octyl silicone oil, and silicone elastomer.

12. The skin care emulsion of claim 11, wherein The triglyceride is obtained by esterification of fatty acids and glycerol, and includes at least one of caprylic / capric triglyceride, C10-C18 fatty acid triglyceride, triheptanoin, tribehenin.

13. The skin emulsion of any one of claims 5-12, wherein, The preservative includes at least one of organic acids, parabens, formaldehyde releasers, and alcohols; The water phase further includes a humectant and a thickening agent.

14. The skin care emulsion of claim 13, wherein, The preservative includes at least one of phenoxyethanol, sodium benzoate, potassium sorbate, hexylene glycol, p-hydroxyacetophenone, caprylyl glycol, caprylhydroxamic acid, pentylene glycol, methylparaben, ethylparaben, ethylhexylglycerin.

15. The skin emulsion of claim 13, wherein, The humectant includes at least one of polyols, polysaccharides, polyethylene glycols, natural factors; The thickening agent includes at least one of polyacrylic acids, polysaccharides, polyurethanes, natural gums, polyoxyethylenes.

16. The skin care emulsion of claim 15, wherein, The humectant is at least one of glycerin, propylene glycol, butylene glycol, pentylene glycol, isoprene glycol, hexylene glycol, sorbitol, xylitol, hyaluronic acid, sodium hyaluronate, fructooligosaccharide, trehalose, polyethylene glycol, sodium lactate, amino acids, betaine, pyrrolidone carboxylic acid and its salt, urea; The thickening agent includes at least one of carbomer, acryloyldimethyltaurate ammonium / VP copolymer, hydroxyethyl acrylate / sodium acryloyldimethyltaurate copolymer, acrylate / C10-30 alkyl acrylate crosslinked copolymer, acryloyldimethyltaurate ammonium, xanthan gum, sodium alginate, guar gum, sodium polyacrylate, sodium polyacrylate grafted starch, gellan gum, cellulose, polyacrylate crosspolymer-6.

17. A process for the preparation of a rhamnolipid self-emulsifying skin care emulsion as claimed in any one of claims 3 to 16, characterized in that, The method includes: Obtaining a water phase, preparing an acid or base containing water phase composition; Obtaining an oil phase, preparing an oil phase composition; Obtaining a skin emulsion, adding the acid or base containing water phase composition into the oil phase composition to obtain the skin emulsion; The rhamnolipid is added to any step of the obtaining of the water phase, the obtaining of the oil phase, or the obtaining of the skin emulsion.

18. The method of claim 17, wherein, The temperature of the oil phase is 70-95℃; And / or, when the water phase and the oil phase are mixed, the mixing is carried out under stirring at 100-700 rpm or homogenization at 3000-10000 rpm, and the temperature of the water phase is greater than or equal to the temperature of the oil phase; After the addition of the raw materials is completed, the mixture is kept under stirring at 60-70℃ for 10-30 min, the stirring speed is 100-700 rpm, and then the stirring is cooled to room temperature.

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