Rhamnolipid self-emulsifying skin care emulsion, preparation method and application

Abstract

The invention discloses a rhamnolipid self-emulsifying skin care emulsion, a preparation method and an application, particularly discloses an application of rhamnolipid in maintaining the pH value of the skin, moisturizing the skin or promoting permeation, and discloses the rhamnolipid self-emulsifying skin care emulsion which is prepared from a water phase and an oil phase, the water phase can contain acid or alkali, and the oil phase can contain oil or water. The mass ratio of rhamnolipid in the skin care lotion is greater than or equal to 0.2%; the pH (Potential of Hydrogen) value of the skin care emulsion is 5.0 to 6.0. The skin care emulsion not only has high moisture retention, high stability and high infiltration capacity, but also has the advantage of maintaining the pH value of the skin for a long time.

Description

Technical Field

[0001] The invention relates to the technical field of preparation of skin care emulsions, and in particular to a rhamnolipid self-emulsifying skin care emulsion, a preparation method and application thereof. Background Art

[0002] Rhamnolipid, as a biosurfactant synthesized by microorganisms, has the advantages of being green and safe, environmentally friendly, mild and highly active. Rhamnolipid is a biosurfactant with the longest research time and the most mature application technology.

[0003] As one of the important means for microorganisms to absorb nutrients from the natural environment, rhamnolipids have a chemical structure very similar to cell membrane phospholipids, and can be constructed into micelles that can easily pass through the cell membrane to deliver substances; rhamnolipids have both hydrophilic sugar rings and lipophilic carbon chains in their chemical structure, and after being made into a uniformly dispersed system, they can easily spread on the skin surface to form a liquid film and exert their amphiphilic activity. In summary, it is not difficult to find that rhamnolipids also have the significance of being used as emulsifiers and penetration enhancers in skin care products.

[0004] However, currently in the field of personal care products, rhamnolipids are usually promoted and used as a surfactant for body cleansing, and end products such as shampoo and facial mousse with added rhamnolipids are already on the market.

[0005] However, using rhamnolipids only as cleaning surfactants, skin care emulsifiers, and penetration enhancers does not fully realize their performance advantages. Summary of the invention

[0006] The technical problem to be solved by the present invention is how to further expand the performance advantages of rhamnolipids to provide a rhamnolipid self-emulsifying skin care lotion, a preparation method and an application thereof.

[0007] The use of rhamnolipids in maintaining skin pH.

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

[0009] Firstly, the present invention provides the use of rhamnolipid in maintaining the pH value of the skin, that is, the rhamnolipid has the effect of maintaining the pH value of the skin when used in a skin care lotion.

[0010] Secondly, the present invention provides the use of rhamnolipid in skin moisturizing, that is, the rhamnolipid has the effect of moisturizing the skin when used in a skin care lotion. When the rhamnolipid is a rhamnolipid mainly of the Rha-Rha-C10-C10 type and the mass proportion of the Rha-Rha-C10-C10 type in the rhamnolipid is 40% or more, the skin moisturizing function of the skin care lotion can be further improved.

[0011] Furthermore, the present invention provides the use of rhamnolipid in promoting penetration, that is, the rhamnolipid has the effect of promoting penetration when used in a skin care lotion. When the rhamnolipid is a rhamnolipid mainly of the Rha-Rha-C10-C10 type and the mass proportion of the Rha-Rha-C10-C10 type in the rhamnolipid is 40% or more, the penetration promoting function of the skin care lotion can be further improved.

[0012] The present invention also provides a rhamnolipid self-emulsifying skin care lotion, the raw materials include an aqueous phase and an oil phase, the aqueous phase may contain acid or alkali, the mass proportion of rhamnolipid in the skin care lotion is ≥0.2%, and the pH value of the skin care lotion is 5.0-6.0.

[0013] Among them, rhamnolipids include four common configurations: Rha-C10, Rha-C10-C10, Rha-Rha-C10, and Rha-Rha-C10-C10. In addition, special structures such as 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. The rhamnolipid in the present invention is preferably a rhamnolipid with Rha-Rha-C10-C10 as the main component, and the mass proportion of Rha-Rha-C10-C10 rhamnolipid in rhamnolipid is more than 40%, preferably 50%-99%.

[0014] In the present invention, the mass proportion of the oil phase and rhamnolipid in the skin care lotion is 2%-80%, preferably 5%-40%; the mass proportion of the water phase in the skin care lotion is 20%-98%, preferably 60%-95%. The oil phase can contain one, multiple or all of various types of oils and fats, preferably at least one of esters, hydrocarbon oils and fats, natural oils and fats, alkanols, fatty acids, and silicone oils.

[0015] Among them, the esters include triglycerides and at least one of monoesters, diesters, polyesters and the like other than triglycerides; the triglycerides described in the present invention preferably include at least one of the chemical substances obtained by esterification of fatty acids and glycerol, such as caprylic / capric triglyceride (GTCC), C10-C18 fatty acid triglycerides, triheptyl, triphenin, etc.; in addition to triglycerides, monoesters, diesters, polyesters and the like preferably include isononyl isononanoate, isopropyl myristate, ethylhexyl palmitate, dibutyl adipate, ester waxes, diisostearyl malate, triisostearyl citrate, pentaerythritol tetrastearate and the like emollient oils and fats containing one or more ester groups.

[0016] The hydrocarbon oils and fats mainly include hydrocarbon skin care oils and fats containing only carbon and hydrogen elements, preferably including at least one of squalane, squalene, white oil, hydrocarbon wax, hydrogenated polyisobutene, isododecane, isohexadecane and the like.

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

[0018] The alkanol mainly includes higher fatty alcohols of C12 and above, preferably at least one of cetearyl alcohol, behenyl alcohol, lauryl alcohol, myristyl alcohol, arachidyl alcohol, and myristyl alcohol.

[0019] The fatty acids mainly include C12 and higher fatty acids, preferably at least one of stearic acid, palmitic acid, myristic acid and the like.

[0020] The silicone oil mainly includes polydimethylsiloxane and various modified products thereof after grafting, blocking and cross-linking, preferably at least one of cyclopentasiloxane, 6-viscosity silicone oil, 100-viscosity silicone oil, 350-viscosity silicone oil, phenyl silicone oil, octyl silicone oil, silicone elastomer and the like.

[0021] As one embodiment, the aqueous phase includes water, a preservative and an acid or a base. Preferably, the aqueous phase also includes at least one of a humectant, a thickener, an emulsifier, and the like.

[0022] The water mentioned in the present invention refers to a large-dose liquid used as a solvent and a dispersion medium, preferably deionized water, purified mineral water, purified seawater, plant tissue fluid (such as loofah water, bamboo juice, birch juice, etc.), fermentation filtrate and other liquids whose main component is water.

[0023] The preservative of the present invention mainly comprises a class of compounds that can inhibit microbial activity and effectively delay the corruption and deterioration of the emulsified system; for example, the preservative comprises at least one of organic acids, parabens, formaldehyde releasers and alcohols, preferably at least one of phenoxyethanol, sodium benzoate, potassium sorbate, hexylene glycol, p-hydroxyacetophenone, caprylyl glycol, caprylylhydroxamic acid, pentylene glycol, methyl paraben, ethyl paraben, ethylhexylglycerin, etc.;

[0024] The base described in the present invention is an inorganic or organic compound that makes the pH of the solution alkaline after being dissolved in water, and the base can undergo a neutralization reaction with the carboxyl group in the unneutralized rhamnolipid structure, and the base preferably includes at least one of potassium hydroxide, sodium hydroxide, triethanolamine, aminomethyl propanol, arginine, ammonia, etc.; the acid described in the present invention is an inorganic or organic compound that makes the pH of the solution acidic after being dissolved in water, and the acid can undergo acidification with the carboxylate ion in the rhamnolipid structure to generate a carboxyl group, and the acid preferably includes at least one of citric acid, lactic acid, fruit acid, salicylic acid, etc.

[0025] The moisturizing agent of the present invention mainly includes cosmetic raw materials that can produce affinity with water and increase and maintain skin moisture in a relatively wide range of humidity changes and for a long time; for example: the moisturizing agent preferably includes at least one of polyols, polysaccharides, polyethylene glycols, and natural factors, and is specifically preferably at least one of glycerol, propylene glycol, butylene glycol, pentylene glycol, isopentyl glycol, hexylene glycol, sorbitol, xylitol, hyaluronic acid, sodium hyaluronate, oligofructose, trehalose, polyethylene glycol, sodium lactate, amino acids, betaine, pyrrolidone carboxylic acid and its salts, urea, etc.;

[0026] The thickener of the present invention mainly includes high molecular polymer substances that can undergo hydrogen bond association, volume expansion, molecular chain entanglement and the like with water after being dispersed in water, ultimately leading to a significant increase in water viscosity and a change in rheological properties; for example, the thickener includes at least one of polyacrylic acid, polysaccharide, polyurethane, natural gum, and polyoxyethylene, preferably at least one of carbomer, ammonium acryloyldimethyltaurate / VP copolymer, hydroxyethyl acrylate / sodium acryloyldimethyltaurate copolymer, acrylic acid (ester) / C10-30 alkyl acrylate cross-linked copolymer, ammonium polyacryloyldimethyltaurate, xanthan gum, sodium alginate, guar gum, sodium polyacrylate, sodium polyacrylate grafted starch, gellan gum, cellulose, and polyacrylate cross-linked polymer-6.

[0027] The present invention also provides a method for preparing the above-mentioned skin care emulsion, including a direct self-emulsification method and a self-emulsification method after dispersion; the direct emulsification method is applicable to rhamnolipids in all forms and pH conditions, and the self-emulsification method after dispersion is mainly suitable for pure acid rhamnolipids.

[0028] Among them, the direct self-emulsification method includes: obtaining the water phase, preparing an acid- or alkali-containing water phase composition; obtaining the oil phase, preparing an oil phase composition; obtaining a skin care lotion, adding the acid- or alkali-containing water phase composition dropwise into the oil phase composition to obtain the skin care lotion; the rhamnolipid can be added to any step of obtaining the water phase, obtaining the oil phase or obtaining the skin care lotion, and the rhamnolipid includes neutralized rhamnolipid and unneutralized rhamnolipid. Since the neutralized rhamnolipid has better hydrophilicity and the unneutralized rhamnolipid has better lipophilicity, preferably, the unneutralized rhamnolipid is added to the step of obtaining the oil phase, and the neutralized rhamnolipid is added to the step of obtaining the water phase.

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

[0030] In the above preparation process, rhamnolipid and other oil phase compositions are pre-heated and mixed, and the heating temperature is 70°C-95°C, preferably 80°C-85°C; after heating and mixing evenly, the acid or base is directly added to the water phase composition; under stirring at 100rpm-500rpm or homogenizing at 3000rpm-10000rpm, when the water and oil phase temperatures are the same, or the water phase temperature is slightly higher than the oil phase temperature, the water phase is gradually added to the oil phase; depending on the formulation composition, a clearly observable phase inversion process may occur; after the phase inversion is completed, the mixture is kept warm and stirred at about 60°C-70°C for 10min-30min, and the stirring speed is 100rpm-700rpm.

[0031] Among them, the post-dispersion self-emulsification method includes: obtaining the water phase to prepare an acid-base-free water phase composition; obtaining the oil phase to prepare an oil phase composition; obtaining the skin care lotion, mixing the acid-base-free water phase composition and the oil phase composition evenly to obtain an oil-water mixture, and adding an acid or a base to the oil-water mixture to obtain the skin care lotion; the rhamnolipid can be added to any step of obtaining the water phase, obtaining the oil phase or obtaining the skin care lotion, and the rhamnolipid includes neutralized rhamnolipid and unneutralized rhamnolipid. Since the neutralized rhamnolipid has better hydrophilicity and the unneutralized rhamnolipid has better lipophilicity, preferably, the unneutralized rhamnolipid is added to the step of obtaining the oil phase, and the neutralized rhamnolipid is added to the step of obtaining the water phase.

[0032] As a specific implementation method, the process is as follows: the oil phase composition containing rhamnolipid and the acid-base-free water phase composition are heated to 70°C-95°C, preferably 80°C-85°C, respectively. After the oil phase composition is melted and mixed into a uniform liquid by heating, the water and oil phases are mixed while ensuring that the temperatures of the water and oil phases are the same or the water phase temperature is slightly higher than the oil phase temperature. The stirring speed during mixing is 100rpm-700rpm, preferably 300rpm-500rpm, or the homogenization speed is 3000rpm-10000rpm, preferably 5000rpm-8000rpm; when the stirring paddle or homogenizer is running, the water and oil phases are directly stirred into a dispersion in which the oil phase is dispersed in the water phase in the form of extremely small droplets. Keep the stirring or homogenizing conditions unchanged, add an appropriate amount of acid or alkali after calculation, keep stirring at about 60℃-70℃ for 10min-30min, preferably 60℃-65℃ for 20min-30min, stirring speed 100rpm-700rpm, preferably 200rpm-300rpm; gradually cool to room temperature after stirring, stop stirring to obtain rhamnolipid self-emulsifying skin care lotion. It should be noted that if the oil phase is difficult to disperse uniformly under stirring or homogenizing conditions due to the difference in composition between the oil and water phases, a small amount of commonly used emulsifiers in cosmetics, such as monoglycerides, PEGs, polyglycerols, glycosides, polysorbates and sorbitan, etc., is added to the formula, accounting for 0.05%-0.5% of the entire formula system, preferably 0.2%-0.3%. This amount cannot stably emulsify all oil phase compositions and only plays a role in auxiliary dispersion.

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

[0034] In the above two preparation methods, the addition of acid or alkali should preferably make the pH range of the emulsion system between 5.0-6.0. In this pH range, part of the carboxyl groups in rhamnolipid are neutralized to become ions, and the other part still maintains the carboxyl structure. The neutralized rhamnolipid has high surface activity, and the unneutralized rhamnolipid is lipophilic. The ionized rhamnolipid emulsifies the unneutralized rhamnolipid together with other oily components into an emulsion, so this type of emulsion is called rhamnolipid self-emulsifying emulsion.

[0035] The technical solution of the present invention has the following advantages:

[0036] 1. When the rhamnolipid provided by the present invention is applied to a skin care lotion, it can not only achieve the emulsifying effect of rhamnolipid itself that has been disclosed, but also achieve the effect of long-term maintenance of skin pH, which has the advantage of effectively expanding the performance of rhamnolipid; and can also effectively maintain good skin moisturizing and penetration-promoting effects.

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

[0038] The mechanism by which the present invention achieves the above-mentioned effects of high moisturizing, stable emulsification, high penetration promotion, and long-term maintenance of skin pH may be:

[0039] Stable emulsification: Before neutralization with alkali, the carboxyl group connected to the end of the carbon chain in the chemical structure of rhamnolipid exists stably as a non-ionic group, but it can undergo anionic-non-ionic 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 emulsification stabilization ability. This feature of rhamnolipid can be used to adjust the surface activity of rhamnolipid and the stability of the colloidal system;

[0040] High penetration enhancement: As one of the important means for microorganisms to absorb nutrients from the natural environment, rhamnolipids have a chemical structure that is very similar to cell membrane phospholipids. They can be constructed into micelles that can easily pass through the cell membrane to deliver substances. By utilizing this feature, rhamnolipids can be used as penetration enhancers in skin care products to improve the penetration enhancement effect, thereby increasing the transdermal absorption rate of the functional ingredients encapsulated by them, thereby achieving a more efficient skin care effect;

[0041] High moisturizing: Rhamnolipid has both hydrophilic sugar rings and lipophilic carbon chains in its chemical structure, and after being made into a uniformly dispersed system, it can easily spread on the skin surface to form a liquid film and exert its amphiphilic activity. The special structure of rhamnolipid allows rhamnolipid to not only reduce the evaporation of water on the skin surface, but also be affinity with water molecules, effectively increase the moisture content of the skin surface, and achieve a high moisturizing effect;

[0042] Long-term maintenance of skin pH: The carboxyl groups in the chemical structure of rhamnolipids are partially neutralized into ions under the action of an appropriate amount of alkali, giving them emulsification and stabilization capabilities. In addition, because rhamnolipids have a pH buffering effect, when the pH of the emulsion system is adjusted between 5.0-6.0, the pH value of the applied skin area is maintained in a stable numerical range that matches the acid-base conditions of healthy skin, ensuring the pH of the skin during application. At the same time, it has been verified that the use of rhamnolipids can also effectively maintain the skin pH within an appropriate range for a longer period of time, with significant results. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

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

[0045] Figure 2 This is a physical picture of the skin care lotion prepared in Example 1 of the present invention. DETAILED DESCRIPTION

[0046] The following examples are provided for a better understanding of the present invention, but are not intended to limit the best mode of implementation, nor to limit the content and protection scope of the present invention. Any product identical or similar to the present invention obtained by anyone under the inspiration of the present invention or by combining the features of the present invention with other prior arts shall fall within the protection scope of the present invention.

[0047] If no specific experimental steps or conditions are specified in the examples, the conventional experimental steps or conditions described in the literature in the field can be used. If no manufacturer is specified for the reagents or instruments used, they are all conventional reagent products that can be obtained commercially.

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

[0049] Rhamnolipids, 1,3-butylene glycol, and carbomer are from Wanhua Chemical; isopentyl glycol is from Kuraray; AVC is from Clariant; glycerin and cetostearyl alcohol are from Procter & Gamble; niacinamide is from DSM-Firmenich; shea butter, phenoxyethanol, and caprylic / capric triglyceride are from BASF; triheptylbenzene is from Orian; parahydroxyacetophenone and 1,2-hexanediol are from Symrise; sodium benzoate is from Merck; PHL is from Indis; squalane, isopropyl myristate, glyceryl stearate / PEG-100 glyceryl stearate (A165) are from Croda; ceramide 3 and polyglyceryl-3 methylglucose distearate (TEGO Care450) are from Evonik; cholesterol is from Cohen; 100 viscosity silicone oil is from Dow Corning; Tween-80, methanol, arginine, and isopropyl alcohol are from Aladdin.

[0050] The units of raw materials without mass specified in the following table are all kg, and rhamnolipids are measured based on the amount of pure product added.

[0051] Example 1

[0052] Skin care lotion, the raw material composition is shown in Table 1.

[0053] Table 1

[0054]

[0055]

[0056] Note: 2R2C in the table is the abbreviation of Rha-Rha-C10-C10. The structure of Rha-Rha-C10-C10 is as follows: Figure 1 As shown in the figure, 30% 2R2C means that the mass proportion of rhamnolipids with 2R2C structure in the total rhamnolipids is 30%, the same below.

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

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

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

[0060] 3. Keep the heating conditions unchanged, turn on the stirring paddle, and stir the oil phase at 500 rpm;

[0061] 4. Add the water phase under the same heat preservation conditions drop by drop into the stirring oil phase at a dropping speed of about 60 d / s;

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

[0063] 6. After cooling to room temperature, the material can be discharged to obtain Figure 2 Skin care lotion as shown.

[0064] Example 2

[0065] Skin care lotion, the raw material composition is shown in Table 2.

[0066] Table 2

[0067]

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

[0069] 1. Prepare the water phase and oil phase compositions according to their solubility characteristics, but do not add alkali to the water phase for the time being;

[0070] 2. Heat the alkali-free water phase and oil phase composition to about 85° C. in the same water bath; 3. Keep the heating conditions unchanged, mix the water and oil phases, and homogenize at a speed of 4000 rpm;

[0071] 4. Add alkali into the homogenizing system and mix evenly;

[0072] 5. After cooling down, keep the temperature at about 60°C and stir for 30 minutes at a stirring speed of 300 rpm;

[0073] 6. After cooling to room temperature, the material can be discharged.

[0074] Example 3

[0075] Skin care lotion, the raw material composition is shown in Table 3.

[0076] Table 3

[0077]

[0078]

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

[0080] 1. Prepare the water phase and oil phase compositions according to their solubility characteristics;

[0081] 2. Heat the water phase and oil phase combination to about 85°C in the same water bath;

[0082] 3. Keep the heating conditions unchanged, turn on the stirring paddle, and stir the oil phase at 500 rpm;

[0083] 4. Add the water phase under the same heat preservation conditions drop by drop into the stirring oil phase at a dropping speed of about 60 d / s;

[0084] 5. After all the water phase is added, keep the temperature at about 60°C and stir for 30 minutes;

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

[0086] The preparation methods and formula ingredients in the above-mentioned Examples 1-3 can be replaced to a certain extent. Among them, the formula of Example 1 can also be used to prepare the emulsion using the process provided in Example 2 of the present invention. There is no strict correspondence between the formula and the preparation process, and they can be used interchangeably with each other. The purpose of the present invention can be achieved under the preparation process parameter conditions disclosed in the present invention.

[0087] The skin care lotions in Examples 1-3 were tested for stability. The appearance of the skin care lotion in Example 1-1 was as follows: Figure 2 As shown, the skin care lotion in the embodiment can maintain stable emulsification without oiling out or breaking after heat storage at 50°C for three months, centrifugation at 5000rpm for 30 minutes, and freeze-thaw cycle for eight weeks; the pH range of the skin care lotion in the embodiment of the present invention is between 5.0-6.0, and the viscosity range is 500cps-80000cps. The skin care lotion in the present invention can also selectively add corresponding active ingredients to the water phase or oil phase composition according to the different desired effects, such as bisabolol, ectoine, VC-IP, niacinamide, 377, etc.; when using, directly take an appropriate amount and evenly apply it to the human epidermis.

[0088] The skin care lotion of the present invention has the moisturizing effect of slowing down the loss of water from the human epidermis and increasing the water content of the human epidermis, has the effect of regulating the acid-base environment of the human epidermis and maintaining the stability of the acid-base environment of the human epidermis for a considerable period of time, has a chemical structure similar to that of biological cell membrane phospholipids, and can promote the percutaneous absorption and effectiveness of other functional ingredients encapsulated by its micelles.

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

[0090] Experimental Example 1-pH Adjustment Effect

[0091] The pH test probe of the German CK non-invasive skin efficacy detector was used to measure the skin pH regulating effect of the sample lotion in the embodiment. Subjects with poor skin condition were selected to pre-determine their epidermal pH value. 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 be prone to oiliness and acne, which is also an unhealthy skin condition. Subjects with too high or too low pH values ​​were selected. For each subject, a corresponding number of 3cm×3cm blocks were marked in the test area. All the test samples prepared in the embodiment were applied in duplicate to each sample's respective test area, and the area without sample application was used as a blank control group. The recommended sampling areas are the cheeks, forehead, outer side of the calf, and inner side of the forearm. The selection area depends on the body condition of each subject. After the subject arrives, first use running water to gently rinse the test area, then use a soft cotton face towel to gently pat the cleaned area dry, repeat the patting action twice, do not rub vigorously to avoid damaging the skin stratum corneum, sit still for more than 30 minutes after washing to slow down and stabilize the body's physiological activity state, mark the corresponding test area with a marker, and use the transcutaneous water loss test probe and water content test probe of the non-invasive skin function detector to measure the value according to the above-mentioned method, test the baseline, 5 minutes and 120 minutes after the product application three times, and calculate the average value of each sample. The subject is required to stop using all cleaning and moisturizing products on the legs during the pre-conditioning period of 3 days before the test, including soap, lotion, sunscreen, mosquito repellent, etc.; 3 days before the test and 24 hours after the measurement, the subject is allowed to gently shave the hair, and the skin cannot be scratched. Avoid exercise, hot drinks or caffeinated beverages within 2 hours before each test, as these behaviors may affect the accuracy and credibility of the measurement results. Any activities that cause sweating are absolutely prohibited. The temperature and relative humidity of the test site were controlled at 20℃±2℃ and 50%±10% respectively.

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

[0093] Table 4 Verification data of skin pH regulation effect

[0094]

[0095]

[0096] It can be seen from the results in Table 4 that the subjects whose skin pH deviates from the normal value have improved their skin pH values ​​to varying degrees after using the present invention. 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 groups such as carboxyl in the rhamnolipid structure, and rhamnolipid can be regarded as an organic acid substance, so it has a pH buffering effect, which is particularly critical. For this reason, the rhamnolipid self-emulsifying skin care lotion can maintain the skin pH value within a reasonable range for a long period of time, and will not cause pH to fluctuate greatly after changes in internal and external factors. This property is exactly what the commonly used nonionic emulsifiers and emollients including A165 and Tween-80 do not have. Therefore, compared to traditional nonionic emulsifiers and emollients, the emulsion prepared using rhamnolipid, on the premise of meeting general stability and efficacy requirements, also has additional skin pH adjustment and stabilization effects, and rhamnolipid has a very rich skin care effect and a broad application prospect.

[0097] Experimental Example 2-Moisturizing Effect

[0098] The transepidermal water loss and water content test probe of the German CK non-invasive skin efficacy detector was used to measure the moisturizing efficacy of the sample lotion in the example. Qualified subjects were selected, and for each subject, a corresponding number of 3cm×3cm blocks were marked in the test area. All the test samples prepared in the example were applied in duplicate to each test area of ​​each sample, and the area without sample application was used as a blank control group. The recommended sampling areas are the cheeks, forehead, outer side of the calf, and inner side of the forearm. The selection area depends on the body condition of each subject. After the subject arrives, first use running water to gently rinse the test area, then use a soft cotton face towel to gently pat the cleaned area dry, repeat the patting action twice, do not rub vigorously to avoid damaging the skin stratum corneum, sit still for more than 30 minutes after washing to slow down and stabilize the body's physiological activity state, mark the corresponding test area with a marker, and use the transcutaneous water loss test probe and water content test probe of the non-invasive skin function detector to measure the value according to the above-mentioned method, test the baseline, 5 minutes and 120 minutes after the product application three times, and calculate the average value of each sample. The subject is required to stop using all cleaning and moisturizing products on the legs during the pre-conditioning period of 3 days before the test, including soap, lotion, sunscreen, mosquito repellent, etc.; 3 days before the test and 24 hours after the measurement, the subject is allowed to gently shave the hair, and the skin cannot be scratched. Avoid exercise, hot drinks or caffeinated beverages within 2 hours before each test, as these behaviors may affect the accuracy and credibility of the measurement results. Any activities that cause sweating are absolutely prohibited. The temperature and relative humidity of the test site were controlled at 20℃±2℃ and 50%±10% respectively.

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

[0100] Table 5 Transepidermal water loss verification data

[0101]

[0102]

[0103]

[0104] Table 6 Epidermal moisture content verification data

[0105]

[0106]

[0107] It can be seen from the results of Tables 5 and 6 that the use of the rhamnolipid self-emulsifying skin care lotion of the present invention can more significantly reduce the transepidermal water loss of the skin and submit the epidermal water content than the skin care lotion prepared with A165 and Tween-80 as emulsifiers. This is because the rhamnolipid structure not only has a lipophilic carbon chain structure, which makes it easy to form a film after being applied to the epidermis, forming a complete covering protective layer, 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. Although the carbon chain and hydrophilic chain in the A165 and Tween-80 structures also have the dual effects of lipophilicity and hydrophilicity, the moisturizing and water-locking effect is not as ideal as rhamnolipid. And rhamnolipid can not only be used as a self-emulsifying emulsifier in the formula, but also as an emollient, and the amount can be larger than A165, so its moisturizing effect is also more obvious. It can be clearly seen from the measured data in the table that when the amount of 2R2C rhamnolipid in the formula increases, such as in Examples 1-1 to 1-4, the transepidermal water loss value of the skin after using the corresponding emulsion is correspondingly smaller, and the epidermal water content is also increased, indicating that the moisturizing effect of rhamnolipid is positively correlated with the content of its 2R2C rhamnolipid; therefore, rhamnolipid with a 2R2C configuration content higher than 40% has a significantly better moisturizing and water-locking effect than rhamnolipid self-emulsifying emulsion with a 2R2C configuration content lower than 40% due to its higher specific gravity of hydrophilic sugar rings.

[0108] In addition, it is worth mentioning that most subjects said that the skin feel of rhamnolipid self-emulsifying lotion is significantly more refreshing than A165 and Tween-80 lotion. This is 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 lighter and more comfortable skin feel, and will not cause the skin to be stuffy and airtight and excessively greasy and cause acne. Rhamnolipid with good water solubility can also gradually sweat and secrete oil on the skin surface as the human body gradually sweats and oils, taking away excessive secretion of oil, controlling the amount of oil coverage on the skin surface within a reasonable range, and not excessively accumulating oil, thereby providing a long-lasting refreshing feeling.

[0109] Experimental Example 3- Penetration-enhancing effect

[0110] Take a piece of complete pig skin, remove the surface hair and remove the subcutaneous fat without damaging its stratum corneum. Thaw the treated skin with PBS buffer for 20 minutes, and then cut into the required size (about 2.5cm×2.5cm square). The side of the pig skin with the stratum corneum faces the donor cavity 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). 1g of skin care lotion prepared with A165 as an emulsifier (Comparative Example 3) and 1g of ceramide 3 skin care lotion prepared by rhamnolipid self-emulsification (Example 3) were added to the donor cavity of different groups for testing the permeability to pig skin, with 3 parallel samples in each group. The receptor chamber was maintained in a water bath at 37°C for 12 hours, and the stirring speed during diffusion was 300r / min. After 12 hours, the pig skin was taken out of the diffusion cell. The remaining sample was removed by washing and gently wiping the surface of the pig skin with absorbent cotton. After removing the stratum corneum of the pig skin, the pig skin was cut into pieces and soaked in an equal amount of methanol for ultrasonic extraction for 20 minutes. The content of ceramide 3 in the extract was detected by high performance liquid chromatography. The chromatographic conditions were: SHIMADZU Shim-pack VP-C18ODS (150mm×4.6mm, 5μm) chromatographic column, C18ODS guard column core, mobile phase V (methanol): V (isopropanol) = 55:45, flow rate 1.0mL·min -1 , column temperature 30°C, UV detector detection, wavelength 205nm, detection cell temperature 40°C. The test results are shown in Table 7 below.

[0111] Table 7 Penetration validation data

[0112]

[0113] It can be seen from the data in Table 7 that the rhamnolipid self-emulsifying skin care lotion prepared by the present invention can better promote the penetration of ceramide 3 into the skin than the skin care lotion prepared by using A165 and Tween-80; and the rhamnolipid with a 2R2C configuration content of ≥40% has a penetration-promoting effect that is significantly better than the rhamnolipid self-emulsifying emulsion with a 2R2C configuration content of less than 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 encapsulated in rhamnolipid micelles into cells, promoting the percutaneous absorption of the encapsulated substances. Microorganisms in nature also use this characteristic to secrete rhamnolipid as one of the important means for them to absorb organic nutrients from the outside world. Using rhamnolipid as a penetration enhancer for functional substances is a way of thinking that conforms to the selection of nature, and has its unique and positive application significance.

[0114] Obviously, the above embodiments are merely examples for the purpose of clear explanation, and are not intended to limit the implementation methods. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived therefrom are still within the scope of protection of the invention.

Claims

1. Application of rhamnolipids in maintaining skin pH.

2. The use according to claim 1, characterized in that: It also includes applications in skin moisturizing and / or skin penetration promotion, wherein the rhamnolipid is a rhamnolipid mainly of the Rha-Rha-C10-C10 type, and the mass proportion of the Rha-Rha-C10-C10 type in the rhamnolipid is 40% or more.

3. A rhamnolipid self-emulsifying skin care lotion, characterized in that: The raw materials include an aqueous phase and an oil phase, the aqueous phase contains acid or alkali, and the mass proportion of rhamnolipid in the skin care lotion is ≥0.2%; the pH value of the skin care lotion is 5.0-6.

0.

4. The skin care lotion according to claim 3, characterized in that The oil phase also includes at least one of esters, hydrocarbon oils, natural oils, alkanols, fatty acids, and silicone oils; and / or, the aqueous phase comprises water, a preservative and an acid or a base; And / or, the total mass proportion of the oil phase and rhamnolipid in the skin care emulsion is 2%-80%, preferably 5%-40%; And / or, the rhamnolipid is a rhamnolipid with Rha-Rha-C10-C10 as the main component, and the mass proportion of Rha-Rha-C10-C10 in the rhamnolipid is 40% or more.

5. The skin care lotion according to claim 4, characterized in that The esters include at least one of monoesters, diesters, and polyesters; And / or, the hydrocarbon oil comprises at least one of squalane, squalene, white oil, hydrocarbon wax, hydrogenated polyisobutylene, isododecane and isohexadecane; And / or, the natural oil comprises at least one of white meadowfoam seed oil, jojoba oil, sweet almond oil, camellia oil, coconut oil, macadamia nut oil, avocado oil, shea butter, cocoa seed butter, mango seed butter, grape seed oil, marula oil, damask rose flower oil, sunflower seed oil, soybean oil, beeswax, ozokerite, carnauba wax, and candelilla wax; And / or, the alkanol is a fatty alcohol of C12 or above; And / or, the fatty acid is C12 or above fatty acid; And / or, the silicone oil includes polydimethylsiloxane and its modified products after grafting, blocking and cross-linking.

6. The skin care lotion according to claim 5, characterized in that The esters include at least one of triglycerides, isononyl isononanoate, isopropyl myristate, ethylhexyl palmitate, dibutyl adipate, ester wax, diisostearyl malate, triisostearyl citrate, and pentaerythritol tetrastearate; preferably, the triglycerides are obtained by esterification of fatty acids and glycerol, including at least one of caprylic / capric triglyceride, C10-C18 fatty acid triglyceride, triheptyl, and triphenin; And / or, the alkanol includes at least one of cetearyl alcohol, behenyl alcohol, lauryl alcohol, myristyl alcohol, arachidyl alcohol, and myristyl alcohol; And / or, the fatty acid includes at least one of stearic acid, palmitic acid, and myristic acid; And / or, the silicone oil includes at least one of cyclopentasiloxane, 6-viscosity silicone oil, 100-viscosity silicone oil, 350-viscosity silicone oil, phenyl silicone oil, octyl silicone oil, and silicone elastomer.

7. The skin care lotion according to any one of claims 4 to 6, characterized in that: The preservative includes at least one of organic acids, parabens, formaldehyde releasers and alcohols, preferably at least one of phenoxyethanol, sodium benzoate, potassium sorbate, hexylene glycol, p-hydroxyacetophenone, caprylyl glycol, caprylhydroxamic acid, pentylene glycol, methyl paraben, ethyl paraben and ethylhexylglycerin; and / or, the base comprises at least one of potassium hydroxide, sodium hydroxide, triethanolamine, aminomethyl propanol, arginine, and ammonia; and / or, the acid comprises at least one of citric acid, lactic acid, fruit acid, and salicylic acid; And / or, the aqueous phase further comprises at least one of a humectant and a thickener.

8. The skin care lotion according to claim 7, characterized in that The moisturizing agent includes at least one of polyols, polysaccharides, polyethylene glycols, and natural factors, preferably at least one of glycerol, propylene glycol, butylene glycol, pentylene glycol, isopentyl glycol, hexylene glycol, sorbitol, xylitol, hyaluronic acid, sodium hyaluronate, oligofructose, trehalose, polyethylene glycol, sodium lactate, amino acids, betaine, pyrrolidone carboxylic acid and its salts, and urea; The thickener includes at least one of polyacrylic acid, polysaccharide, polyurethane, natural gum and polyoxyethylene, preferably at least one of carbomer, ammonium acryloyldimethyltaurate / VP copolymer, hydroxyethyl acrylate / sodium acryloyldimethyltaurate copolymer, acrylic acid (ester) / C10-30 alkyl acrylate cross-linked copolymer, ammonium polyacryloyldimethyltaurate, xanthan gum, sodium alginate, guar gum, sodium polyacrylate, sodium polyacrylate grafted starch, gellan gum, cellulose and polyacrylate cross-linked polymer-6.

9. A method for preparing a rhamnolipid self-emulsifying skin care lotion, characterized in that: include: Acquiring an aqueous phase, preparing an aqueous phase composition containing an acid or a base, or preparing an acid-free and alkali-free aqueous phase composition; Obtaining the oil phase and preparing the oil phase composition; The skin care lotion is obtained by dropping an acid- or alkali-containing aqueous phase composition into an oil phase composition to obtain the skin care lotion; or the acid- and alkali-free aqueous phase composition and the oil phase composition are uniformly mixed to obtain an oil-water mixture, and an acid or alkali is added to the oil-water mixture to obtain the skin care lotion; The rhamnolipid is added to any step of obtaining the water phase, the oil phase or the skin care lotion.

10. The preparation method according to claim 9, characterized in that: The oil phase temperature is 70°C-95°C; and / or, when the water phase and the oil phase are mixed, the mixing is performed under a stirring condition of 100 rpm to 700 rpm or a homogenizing condition of 3000 rpm to 10000 rpm, and the water phase temperature is ≥ the oil phase temperature; After the raw materials are added, stir at 60°C-70°C for 10min-30min, with a stirring speed of 100rpm-700rpm, and then stir and cool to room temperature.

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