Oil-in-water microemulsion

Abstract

The invention discloses an oil-in-water microemulsion, and relates to the technical field of microemulsion preparations, the oil-in-water microemulsion comprises an active substance, a surfactant, a cosurfactant, polyol, grease and water, the surfactant is composed of polyglycerol-10 oleate and polyglycerol-2 oleate, and the cosurfactant is PEG-7 glyceryl cocoate. The oil-in-water microemulsion disclosed by the invention has the characteristics of high grease content, mildness, no irritation and stable thermodynamic property.

Description

Technical Field

[0001] The present invention relates to the technical field of microemulsion preparations, and in particular to an oil-in-water microemulsion. Background Art

[0002] Emulsions are generally composed of two immiscible liquids, of which the liquid in the form of droplets is called the dispersed phase, and the liquid in continuous flow is called the continuous phase. Since the dispersed phase and the continuous phase are immiscible, in order to maintain a stable thermodynamic and kinetic state, it is often necessary to add a surfactant to improve the interfacial tension. In the field of cosmetics, the two common phases of emulsions are oil phase and water phase. According to the types of dispersed phase and continuous phase, emulsions can be divided into water-in-oil type (W / O) and oil-in-water type (O / W). Among them, an emulsion with an oil phase as the continuous phase and a water phase as the dispersed phase is a W / O emulsion; an emulsion with a water phase as the continuous phase and an oil phase as the dispersed phase is an O / W emulsion.

[0003] In addition, depending on the size and thermodynamic stability of the dispersed phase particles, emulsions can be divided into coarse emulsions, nanoemulsions and microemulsions. The particle size of the dispersed phase of the coarse emulsion is 1-100μm, which is thermodynamically and kinetically unstable. The particle size of the dispersed phase of the nanoemulsion is 20-500nm, which is thermodynamically unstable but kinetically stable. The particle size of the dispersed phase of the microemulsion is 10-100nm, which is thermodynamically stable. Although nanoemulsions are very similar to microemulsions, the particle size of microemulsions is generally smaller, the thermodynamic properties are more stable, and it is not easy to agglomerate at high temperatures, which means that it has more significant advantages in storage.

[0004] The formation mechanism of microemulsion is very complicated. According to Winsor's R ratio theory, the spontaneous formation of microemulsion is related to the interaction between surfactant, co-surfactant, water phase and oil phase. Therefore, microemulsion can also be divided into a variety of different systems according to surfactant / oil / water. There are many kinds of microemulsion systems known at present, and the common ones are AS / CTAB / short-chain carbon alcohol / n-heptane / water system, SDS / CTAB / short-chain carbon alcohol / n-heptane / water system, n-butane / hexane / water system and Tween-80 / CTAB system, etc. (see "Effect of ionic and nonionic surfactants on the phase behavior and physicochemical characteristics of pseudoternary systems involving polyoxyethylene (20) sorbitan monooleate", Padmini Suna et al., "Surfaces and Interfaces" and "Effect of co-surfactant on the formation of microemulsions by anionic / cationic surfactant compounding", Li Ying et al., "Applied Chemistry", Vol. 20, No. 5). However, most of the known surfactants are irritating to the skin. Long-term contact with the skin may cause damage to the skin barrier, which poses a great safety risk to consumers. Polyglycerol fatty acid esters are a new type of polyhydroxy ester non-ionic surfactants, which are highly mild and safe, and have excellent performance. Their hydrophilicity increases with the increase of glycerol polymerization degree, while their lipophilicity varies with the different fatty acid alkyl groups. By changing the polyglycerol polymerization degree, fatty acid type and esterification degree, a series of polyglycerol fatty acid ester products with HLB values ​​ranging from 1 to 20 and different properties from lipophilicity to hydrophilicity can be obtained, so that they can be applied to different products or fields. In addition, it has been reported that PEG-7 glyceryl cocoate is miscible with oils and fats and has good emulsification and moisturizing properties.

[0005] Chinese patent application CN116035931A discloses a microemulsion using only polyglycerol fatty acid ester as surfactant, which has the characteristics of high safety and high stability. However, on the one hand, it reduces the content of oil in the emulsion system, and on the other hand, through a higher emulsifier-oil ratio, more surfactant is used to emulsify a portion of oil to obtain a microemulsion with high stability, which undoubtedly sacrifices the moisturizing performance and skin feel of the microemulsion. Summary of the invention

[0006] The present invention provides an oil-in-water microemulsion, which increases the oil content in the emulsion system and reduces the emulsifier-oil ratio while ensuring high stability, high temperature resistance and high safety, thereby achieving improvement in the moisturizing performance and skin feel of the microemulsion using polyglycerol fatty acid ester as a surfactant.

[0007] The present invention provides an oil-in-water microemulsion, comprising an active substance, a surfactant, a co-surfactant, a polyol, oil and water, wherein the surfactant is composed of polyglycerol-10 oleate and polyglycerol-2 oleate, and the co-surfactant is PEG-7 glyceryl cocoate.

[0008] The present disclosure improves the surfactant system in the microemulsion system by rationally matching polyglycerol-10 oleate, polyglycerol-2 oleate and PEG-7 glyceryl cocoate, optimizes the HLB value of the emulsion system, successfully increases the content of oil that can be added to the emulsion system, and reduces the emulsifier-oil ratio. In the microemulsion provided by the present disclosure, the oil content can be as high as 10%, and the emulsifier-oil ratio can be as low as 0.5. A high content of oil can effectively improve the moisturizing performance and skin feel of the microemulsion, allowing consumers to obtain a better user experience.

[0009] In some embodiments, the mass ratio of the polyglycerol-10 oleate to the polyglycerol-2 oleate is 2.7:2.3.

[0010] The microemulsion system is very sensitive to the HLB value of the surfactant. The HLB value of the surfactant is the key to whether the microemulsion system can be stably formed, and the HLB value of the surfactant is mainly determined by the type and ratio of the components that constitute the surfactant. After a lot of creative work, the inventors of the present disclosure found that the microemulsion has the best stability when the mass ratio of polyglycerol-10 oleate and polyglycerol-2 oleate is 2.7:2.3. When the mass ratio changes, the stability of the microemulsion will deteriorate or even make it difficult to form a microemulsion.

[0011] In some embodiments, the mass ratio of the surfactant to the oil is less than 1. In some embodiments, the mass ratio of the surfactant to the oil is 1:2.

[0012] In some embodiments, the oil is composed of ethylhexyl palmitate and squalane, and the mass ratio of ethylhexyl palmitate to squalane is 7.5:2.5.

[0013] In some embodiments, the mass ratio of the surfactant, the co-surfactant, the polyol and the oil is 5:1:15:10.

[0014] In some embodiments, the polyol is composed of 1,3-butanediol and glycerol, and the mass ratio of the 1,3-butanediol to glycerol is 2: 1. The polyol has a certain moisturizing ability and can further enhance the moisturizing effect of the microemulsion.

[0015] In some embodiments, the active substance includes one or more of ectoine, hydroxypropyl tetrahydropyrantriol, hydroxypinacolone retinoic acid ester, ergothioneine, ascorbyl tetraisopalmitate, and active polypeptides.

[0016] In some embodiments, the active polypeptides include one or more of β-alanylhydroxyprolyldiaminobutyric acid benzylamine, cono peptide, carnosine, tripeptide-1, acetyl tetrapeptide-3, acetyl tetrapeptide-9, acetyl tetrapeptide-11, acetyl hexapeptide-8, acetyl octapeptide-3, palmitoyl tripeptide-1, palmitoyl tripeptide-5, palmitoyl tetrapeptide-7, palmitoyl pentapeptide-4, hexapeptide-9, and nonapeptide-1.

[0017] In some embodiments, the oil-in-water microemulsion of the present disclosure further comprises a preservative. The amount of the preservative added may depend on the actual conditions of the microemulsion, and the mass percentage in the microemulsion is generally 0.1%-5%. In some embodiments, the preservative includes, but is not limited to: ethylhexylglycerol, 1,2-hexanediol, p-hydroxyacetophenone, and the like.

[0018] The present disclosure has the following advantages and effects:

[0019] 1. The present invention obtains a microemulsion with high oil content by reasonably combining polyglyceryl-10 oleate, polyglyceryl-2 oleate and PEG-7 glyceryl cocoate. The microemulsion has excellent stability, high temperature resistance and high safety, and its moisturizing performance and skin feel are significantly improved.

[0020] 2. The microemulsion disclosed in the present invention has the characteristics of small particle size, uniform distribution, and stable thermodynamic properties, and can still maintain the stability of the emulsion dispersion system when used as a cosmetic additive. DETAILED DESCRIPTION

[0021] In order to make the objects, features and advantages of the present disclosure more obvious and understandable, the present disclosure is further described in detail below in conjunction with embodiments. Obviously, the described embodiments are part of the embodiments of the present disclosure, rather than all of the embodiments. Based on the embodiments in the present disclosure, all other embodiments obtained by ordinary technicians in the field without creative work are within the scope of protection of the claims attached to the present disclosure.

[0022] Unless otherwise specified, the experimental reagents and materials used in the present disclosure can be obtained commercially.

[0023] Example

[0024] Some oil-in-water microemulsions are prepared as follows:

[0025] Table 1 Example formulation

[0026]

[0027]

[0028] Note: “ / ” means not added.

[0029] Conopeptide X is a product sold by Shenzhen Weiqi Technology Co., Ltd., and is composed of 1.5% 1,2-hexanediol, 0.2% ethylhexylglycerol, 0.05% acetyl hexapeptide-8, 0.0025% conopeptide, and 98.2475% water by mass percentage.

[0030] Weifuyan PLUS is a product sold by Shenzhen Weiqi Technology Co., Ltd., and is composed, by mass percentage, of 2.0% pentylene glycol, 1.0% steareth-20, 1.0% 1,2-hexanediol, 0.12% tripeptide-1, 0.02% hexapeptide-9, 0.02% acetyl tetrapeptide-9, 0.01% palmitoyl pentapeptide-4, 0.005% palmitoyl tetrapeptide-7, 0.005% acetyl hexapeptide-8, 30% glycerin and 65.82% water.

[0031] Table 2 Comparative Example Formula

[0032]

[0033] Note: “ / ” means not added.

[0034] According to the formula in Table 1 and Table 2, the surfactant and oil in the formula amount are placed in a container, heated to 75-80°C under stirring, fully dissolved and mixed, cooled to room temperature, and the oil phase is obtained; the co-surfactant, 1,3-butanediol, glycerol, hexylene glycol, p-hydroxyacetophenone, and purified water in the formula amount are placed in a container, heated to 75-80°C under stirring, fully dissolved and mixed, cooled to room temperature, and the active substance in the formula amount is added to fully dissolve and mix to obtain the water phase; the water phase is gradually added to the oil phase under stirring (the dropping speed is 1-20mL / min), and stirring is continued until the composite system is fully mixed. The appearance properties of each sample are shown in Table 3.

[0035] Table 3 Appearance characteristics of each sample

[0036] sample Appearance Example 1 Translucent microemulsion with blue light Example 2 Translucent microemulsion with blue light Example 3 Translucent microemulsion with blue light Example 4 Translucent microemulsion with blue light Example 5 Translucent microemulsion with blue light Comparative Example 1 Opaque white emulsion Comparative Example 2 Translucent microemulsion with blue light Comparative Example 3 Translucent microemulsion with blue light Comparative Example 4 Translucent microemulsion with blue light Comparative Example 5 Translucent microemulsion with blue light Comparative Example 6 Opaque white emulsion Comparative Example 7 Opaque white emulsion Comparative Example 8 Translucent microemulsion with blue light Comparative Example 9 Almost opaque white emulsion

[0037] Examples 1-5 formed a translucent microemulsion with blue light, while Comparative Examples 1, 6 and 7 could not form a microemulsion, and they were stratified after standing for a short time. The average particle size and particle size distribution index were further determined using a Malvern particle size analyzer. The results showed that the average particle size of the microemulsion of Example 1 was 102.80 nm, and the PDI particle size distribution index was 0.370, which proved that the particle size of the microemulsion of Example 1 was small, the particle size distribution was uniform, and it had excellent thermodynamic stability. Examples 2-5 also showed the characteristics of small particle size and uniform particle size distribution. In contrast, the average particle size of the emulsion of Comparative Example 9 was 234.40 nm, the PDI particle size distribution index was 0.381, and the appearance was a nearly opaque white milky white, proving that what was formed in Comparative Example 9 was not a microemulsion but a submicroemulsion or a nanoemulsion.

[0038] The microemulsion samples obtained above were subjected to room temperature stability test, heat resistance test, freezing test and freeze-thaw test. The room temperature stability test refers to the sample being stored at room temperature of 20-25°C for three months, the heat resistance test refers to the sample being stored at 45°C for three months, the freezing test refers to the sample being stored at -10°C for three months, and the freeze-thaw test refers to the sample being subjected to three hot and cold cycles at -10°C / 45°C. The results are shown in Table 4 below.

[0039] Table 4 Stability test results

[0040]

[0041] Note: If the room temperature stability is poor, no further studies on heat resistance, freezing, freeze-thaw resistance, etc. will be conducted.

[0042] From the above results, it can be seen that compared with Example 1, Comparative Examples 1 to Comparative Examples 6 only differ in the mass ratio of polyglycerol-10 oleate and polyglycerol-2 oleate. However, Comparative Examples 2 to 5 all showed stratification after standing for a period of time, and Comparative Examples 1 and Comparative Examples 6 could not even form a microemulsion at all. This proves that the mass ratio of polyglycerol-10 oleate and polyglycerol-2 oleate determines the thermodynamic properties of the microemulsion of the present invention, and is one of the decisive factors for whether the microemulsion of the present invention can be formed and whether it is stable.

[0043] Compared with Example 1, Comparative Example 7 uses polyglyceryl-2 isostearate to replace polyglyceryl-2 oleate, and Comparative Example 8 uses polyglyceryl-10 myristate to replace polyglyceryl-10 oleate. Although the physicochemical properties of polyglyceryl-2 isostearate and polyglyceryl-2 oleate are very similar, Comparative Example 7 proves that the emulsion system after replacement has undergone tremendous changes, and using polyglyceryl-2 isostearate to replace polyglyceryl-2 oleate will cause microemulsion to be unable to form. The physicochemical properties of polyglyceryl-10 myristate and polyglyceryl-10 oleate are also very similar, but Comparative Example 8 also proves that the emulsion system after replacement has undergone tremendous changes, and the stability of the formed microemulsion is poor. The above description shows that there is no substitutability between similar polyglyceryl fatty acid esters, and the combination of polyglyceryl-10 oleate and polyglyceryl-2 oleate is the key to the formation and stability of the microemulsion system.

[0044] Compared with Example 1, Comparative Example 9 removes the cosurfactant PEG-7 glyceryl cocoate, and correspondingly increases the mass percentage concentration of the surfactant polyglyceryl-10 oleate and polyglyceryl-2 oleate, and keeps the mass ratio of polyglyceryl-10 oleate and polyglyceryl-2 oleate at 2.7:2.3, but Comparative Example 9 cannot form a microemulsion, but forms a nanoemulsion or submicroemulsion with a larger particle size. Comparative Example 9 proves that PEG-7 glyceryl cocoate is a necessary cosurfactant for the polyglyceryl-10 oleate and polyglyceryl-2 oleate system, and it is difficult to prepare a microemulsion with a high oil content by simply using polyglyceryl fatty acid esters as surfactants.

[0045] In the present disclosure, relational terms such as first and second, etc. are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or terminal device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or terminal device. In the absence of further restrictions, the elements defined by the statement "comprise one..." do not exclude the presence of other identical elements in the process, method, article or terminal device including the elements.

[0046] Although the specific embodiments of the present disclosure are described for the purpose of illustration, various modifications or improvements may be made by those skilled in the art without departing from the spirit and scope of the present disclosure. These modifications or improvements should all fall within the scope of the appended claims of the present disclosure.

Claims

1. An oil-in-water microemulsion, characterized in that: The invention comprises active substances, surfactants, auxiliary surfactants, polyols, oils and water. The surfactants are composed of polyglycerol-10 oleate and polyglycerol-2 oleate, and the auxiliary surfactant is PEG-7 glyceryl cocoate.

2. The oil-in-water microemulsion according to claim 1, characterized in that The mass ratio of the polyglycerol-10 oleate to the polyglycerol-2 oleate is 2.7:2.

3.

3. The oil-in-water microemulsion according to claim 1 or 2, characterized in that The mass ratio of the surfactant to the oil is less than 1.

4. The oil-in-water microemulsion according to claim 3, characterized in that The mass ratio of the surfactant to the oil is 1:

2.

5. The oil-in-water microemulsion according to claim 1 or 2, characterized in that: The oil is composed of ethylhexyl palmitate and squalane, and the mass ratio of ethylhexyl palmitate to squalane is 7.5:2.

5.

6. The oil-in-water microemulsion according to claim 1 or 2, characterized in that The mass ratio of the surfactant, the co-surfactant, the polyol and the oil is 5:1:15:

10.

7. The oil-in-water microemulsion according to claim 1 or 2, characterized in that The polyol consists of 1,3-butanediol and glycerol, and the mass ratio of the 1,3-butanediol to the glycerol is 2:

1.

8. The oil-in-water microemulsion according to claim 1 or 2, characterized in that: The active substance comprises one or more of ectoine, hydroxypropyl tetrahydropyrantriol, hydroxypinacolone retinoic acid ester, ergothioneine, ascorbyl tetraisopalmitate, and active polypeptide.

9. The oil-in-water microemulsion according to claim 8, characterized in that The active polypeptides include one or more of β-alanylhydroxyprolyldiaminobutyric acid benzylamine, conopeptide, carnosine, tripeptide-1, acetyl tetrapeptide-3, acetyl tetrapeptide-9, acetyl tetrapeptide-11, acetyl hexapeptide-8, acetyl octapeptide-3, palmitoyl tripeptide-1, palmitoyl tripeptide-5, palmitoyl tetrapeptide-7, palmitoyl pentapeptide-4, hexapeptide-9, and nonapeptide-1.

10. The oil-in-water microemulsion according to claim 1, characterized in that Also includes preservatives.

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