Preparation method and application of polyglycerol fatty acid ester O / W / O type multiple emulsion

Abstract

The invention relates to the field of cosmetics, and particularly discloses a polyglycerol fatty acid ester O / W / O type multiple emulsion as well as a preparation method and application thereof. The polyglycerol fatty acid ester O / W / O multiple emulsion provided by the invention is prepared from the following components: propylene glycol serving as a stabilizer, pullulan serving as a thickener, polyglycerol-10 laurate serving as a water-soluble emulsifier, polyglycerol-2 dipolyhydroxystearate serving as an oil-soluble emulsifier and polyglycerol-3 diisostearate serving as an oil-soluble emulsifier. According to the multi-emulsion disclosed by the invention, the polyglycerol fatty acid ester emulsifier with a natural source is adopted, so that the multi-emulsion has environmental degradability and safety to a human body. The product prepared by the method disclosed by the invention has the characteristics of safety, environmental friendliness, skin friendliness, simplified production process and the like.

Description

Technical Field

[0001] The present invention belongs to the technical field of cosmetics, and more specifically, relates to a preparation method and application of a polyglycerol fatty acid ester O / W / O type multiple emulsion. Background Art

[0002] An emulsion is a dispersed system in which at least one liquid is dispersed in an immiscible liquid as droplets, with the droplets typically ranging in size from 100 nanometers to 100 microns. First discovered in 1925 by German biochemist Seifritz, multiple emulsions are essentially a ternary system with two membranes and three phases: a composite emulsion structure in which a dispersed phase exists within droplets of another dispersed phase. This structure allows the oil and water phases to be separated by two membranes into three mutually immiscible regions (oil / water / oil, water / oil / water). Within these three distinct regions, different active substances can be dissolved, preventing interaction between them and allowing the active substances to be slowly released through the two membranes. Due to their unique three-phase structure, multiple emulsions can be used to encapsulate active ingredients and as carriers for drug delivery, finding widespread application in the food, pharmaceutical, and cosmetic industries.

[0003] The two-step emulsification method is currently the most commonly used preparation method, offering advantages such as high coverage and stability. The two-step emulsification method for preparing O / W / O multiple emulsions involves the following steps: First, the internal oil phase and the aqueous phase containing a hydrophilic emulsifier are used to prepare the internal phase O / W particles using a high-energy emulsification method. The O / W emulsion prepared in the first step is then added to the oil phase containing a lipophilic emulsifier and stirred. The final O / W / O multiple structure emulsion is then formed using a low-energy stirring emulsification method.

[0004] However, multiple emulsions are thermodynamically unstable systems prone to flocculation, coalescence, creaming, Ostwald ripening, and sedimentation. Their preparation processes are complex, their stability is poor, their formulations are unique, and the mechanisms underlying their formation and stability remain unclear. Therefore, the preparation of stable multiple emulsions remains a research hotspot in this field. Currently, international research primarily focuses on W / O / W multiple emulsions, while research on O / W / O multiple emulsions, which offer comparable advantages, is relatively scarce. From an emulsifier safety perspective, some commonly used emulsifiers pose potential risks. For example, traditional nonionic emulsifiers, such as polysorbates, may degrade into cytotoxic substances during metabolism in the body, potentially posing health risks to humans with long-term exposure. Anionic emulsifiers, such as sodium lauryl sulfate, possess strong surface activity and can disrupt cell membranes, potentially irritating the skin and mucous membranes and interfering with the body's normal physiological barrier function. Furthermore, the complexity of multiple emulsion systems leads to relatively high emulsifier dosages, further increasing the likelihood of adverse reactions such as allergies and irritation caused by emulsifier residues. At the same time, some emulsifiers are difficult to degrade in the environment, causing ecological pollution and not meeting the requirements of green chemistry and sustainable development. Summary of the Invention

[0005] This invention aims to provide a polyglycerol fatty acid ester O / W / O multiple emulsion to address the difficulties faced by traditional emulsifiers in stabilizing the interface, particularly poor stability under long-term storage or temperature fluctuations. It also addresses the safety concerns of existing cosmetics, where many active ingredients are derived from chemical synthesis. The emulsion also achieves effective encapsulation and gradual release of active substances. Through careful raw material performance screening and optimized preparation methods, the present invention has successfully developed an O / W / O skin care emulsion with excellent stability, a refreshing feel, and easy absorption.

[0006] The specific technical solutions adopted in the present invention are as follows.

[0007] A polyglycerol fatty acid ester O / W / O type multiple emulsion is prepared by mixing an O / W emulsion with an external oil phase and then subjecting it to secondary emulsification. The invention is characterized in that: first, oil A, deionized water, emulsifier I, pullulan, and stabilizer are mixed in a mass ratio of (8-15):(28-40):(0.5-3):(0.5-5):(1-5) and then emulsified to prepare the O / W emulsion; then, emulsifier II, beeswax, and liquid oil B are uniformly mixed in a mass ratio of (2-6):(1-5):(40-55) to prepare the external oil phase; finally, the O / W emulsion and the external oil phase are mixed in a mass ratio of 4:6-5:5 and then subjecting it to secondary emulsification to prepare the O / W emulsion.

[0008] Furthermore, the liquid oil A is one or more of caprylic / capric triglyceride, isopropyl myristate, isopropyl palmitate, and ethyl palmitate.

[0009] Furthermore, the emulsifier I is any one of polyglyceryl-10 laurate, polyglyceryl-10 myristate, polyglyceryl-10 palmitate, polyglyceryl-10 stearate, polyglyceryl-10 oleate, and polyglyceryl-10 isostearate.

[0010] Furthermore, the stabilizer is one or more of glycerol, butylene glycol, propylene glycol, 1,3-butylene glycol, and 1,3-propylene glycol.

[0011] Furthermore, the emulsifier II is one or more of polyglyceryl-3 polyricinoleate, polyglyceryl-3 diisostearate, and polyglyceryl-2 dipolyhydroxystearate.

[0012] Furthermore, the liquid oil B is one or more of octane, dodecane, hexadecane, and squalane.

[0013] The preparation method of the O / W / O type multiple emulsion of the present invention comprises the following steps:

[0014] (1) Emulsifier I and liquid oil A are mixed in proportion and heated in a water bath to obtain an oil phase; a stabilizer and pullulan are added to deionized water in proportion to obtain an aqueous phase; the oil phase I and the aqueous phase are mixed in a mass ratio of 2:8 to 3:7 and emulsified to obtain an O / W emulsion;

[0015] (2) Emulsifier II, beeswax, and liquid oil B were mixed in proportion and stirred at 200-400 rpm in a constant temperature water bath at 60°C until they were completely dissolved to obtain an external oil phase;

[0016] (3) adding the O / W emulsion to the external oil phase in a mass ratio of 4:6 to 5:5, and performing secondary emulsification to obtain the polyglycerol fatty acid ester O / W / O type multiple emulsion;

[0017] Furthermore, in step (1), the process of slowly adding the oil phase to the water phase for emulsification is to perform high-speed shear homogenization mixing at a water bath temperature of 60-90° C. and a shear rate of 10,000-12,000 rpm for 5-8 minutes to obtain an O / W emulsion.

[0018] Furthermore, in step (3), the O / W emulsion is slowly added dropwise to the external oil phase for secondary emulsification, and low-speed shear homogenization mixing is performed at a water bath temperature of 60-90° C. and a shear rate of 3000-6000 rpm for 3-5 minutes to obtain a structurally stable O / W / O multiple emulsion system.

[0019] In the preparation method of the present invention, in order to obtain dispersed phase droplets of the O / W / O multiple emulsion system with small particle size and stable structure, the first homogenization requires a higher shear rate and a longer time; in order not to destroy the internal phase oil droplets and form a stable multiple emulsion, the second homogenization requires a lower shear rate and an appropriate time. Therefore, process conditions are important conditions for preparing stable multiple emulsions.

[0020] Preferably, in the preparation method of the present invention, the liquid oil A is one or more of caprylic / capric triglyceride (GTCC), isopropyl myristate, isopropyl palmitate, and ethyl palmitate.

[0021] Preferably, in the preparation method of the present invention, the emulsifier I is polyglyceryl-10 laurate, polyglyceryl-10 myristate, polyglyceryl-10 palmitate, polyglyceryl-10 stearate, polyglyceryl-10 oleate, or polyglyceryl-10 isostearate. More preferably, the emulsifier I is polyglyceryl-10 laurate or polyglyceryl-10 isostearate.

[0022] Preferably, in the preparation method of the present invention, the stabilizer is glycerol, butylene glycol, propylene glycol, 1,3-butylene glycol, or 1,3-propylene glycol.

[0023] Preferably, in the preparation method of the present invention, the emulsifier II is one or more of polyglyceryl-3 polyricinoleate, polyglyceryl-3 diisostearate, and polyglyceryl-2 dipolyhydroxystearate. More preferably, the emulsifier II is a mixture of polyglyceryl-2 dipolyhydroxystearate and polyglyceryl-3 diisostearate. Further preferably, the ratio of polyglyceryl-2 dipolyhydroxystearate to polyglyceryl-3 diisostearate is 9-5:1-5.

[0024] Preferably, in the preparation method of the present invention, the liquid oil B is one or more of octane, dodecane, hexadecane, and squalane.

[0025] The O / W / O type multiple emulsion is composed of: 28%-40% deionized water, 8%-15% oil A, 40%-55% oil B, 0.5%-3% emulsifier I, 2%-6% emulsifier II, 1%-5% stabilizer, 0.5%-5% pullulan, and 1%-5% beeswax.

[0026] Preferably, the composition of the O / W / O type multiple emulsion is: deionized water 28%-40%, oil A 8%-15%, oil B 40%-55%, emulsifier I 2%-3%, emulsifier II 4%-5%, stabilizer 2%-3%, pullulan 2%-4%, and beeswax 2%-3%.

[0027] Currently, international research focuses primarily on W / O / W multiple emulsions. Research on O / W / O multiple emulsions, which offer comparable advantages, is relatively scarce. The O / W / O multiple emulsion products provided by the present invention demonstrate significant technical advantages in terms of emulsion stability, preparation efficiency, and raw material properties.

[0028] In terms of emulsion stability, a stable oil-in-water-in-oil (O / W / O) multiple emulsion structure was constructed by precisely controlling the type, dosage and ratio of polyglycerol fatty acid esters with other components. By screening O / W emulsifiers and thickeners, regulating the interfacial properties between the emulsifier and the oil phase and the water phase, a stable interfacial film was formed. By optimizing the compounding system of polyglycerol fatty acid ester emulsifiers, a stable oil-in-water-in-oil (O / W / O) emulsion system was obtained, which effectively suppressed the phase separation, demulsification and other phenomena of the emulsion during storage, transportation and use. The stability test showed that the O / W / O type multiple emulsion product provided by the invention was stored in a high temperature environment of 45°C for 7 days, and the emulsion did not show stratification or demulsification; after being stored in a low temperature environment of -10°C for 7 days, the emulsion was still able to maintain a uniform state after recovery to room temperature, and no stratification occurred under the centrifugal stability test (3000rpm, 30min). The product maintains stable performance during complex storage, transportation and use.

[0029] In the product formula of the present invention, emulsifier I and emulsifier II are polyglycerol fatty acid ester emulsifiers selected from natural renewable resources, which can have excellent compatibility with other commonly used cosmetic ingredients (such as active substances, moisturizers, fragrances, etc.). The O / W / O type multiple emulsion product prepared based on polyglycerol fatty acid ester emulsifiers can dissolve different active substances in the oil phase and the water phase, effectively encapsulate and stabilize a variety of functional ingredients, prevent them from interacting with each other, and the functional ingredients are slowly released through the two layers of membrane, so that the human skin obtains a more sufficient absorption effect. At the same time, polyglycerol fatty acid ester emulsifiers are not only non-irritating to the skin, but also can give the skin a soft touch and smooth and comfortable skin feel, and show excellent stability in acidic, alkaline and neutral environments, are not prone to hydrolysis reactions, and show good environmental adaptability and product compatibility. In addition, polyglycerol fatty acid ester emulsifiers have the natural property of complete biodegradability, can be completely degraded in the environment, have no biological toxicity or side effects on the human body, and have environmental friendliness and human safety that are difficult to match with traditional synthetic emulsions.

[0030] The O / W / O type multiple emulsion product provided by the present invention is applied in the food field, can effectively embed bioactive substances to protect them from damage by the gastrointestinal environment and other environments, control their release, mask unpleasant flavors, prepare low-fat and low-calorie foods without changing the original flavor, and add it to the food system to enhance the food properties.

[0031] The O / W / O type multiple emulsion product provided by the present invention is applied in the pharmaceutical field, and can simultaneously deliver hydrophilic and hydrophobic bioactive substances, control the release of drugs and avoid them being damaged by the gastrointestinal environment, and target the drugs to specific lesions.

[0032] Therefore, the O / W / O type multiple emulsion provided by the present invention has broad application prospects in the fields of food, medicine and cosmetics. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 This is a micrograph of the O / W / O multiple emulsion prepared in Example 1 of the present invention. DETAILED DESCRIPTION

[0034] The present invention will be described in detail below in conjunction with specific embodiments and examples, and the advantages and various effects of the present invention will be more clearly presented. It should be understood by those skilled in the art that these specific embodiments and examples are for illustrating the present invention, rather than for limiting the present invention.

[0035] [Example 1]

[0036] The viscous liquid of polyglyceryl-10 laurate and GTCC were mixed in proportion and stirred at 300 rpm in a constant temperature water bath at 60°C for 3 minutes until they were completely miscible. Pullulan and propylene glycol were simultaneously dissolved in deionized water. The stabilizer was fully dissolved under the same temperature conditions. The aqueous phase was slowly added to the oil phase system, first stirred at 300 rpm, and then homogenized at 10,000 rpm at room temperature for 5 minutes to obtain an O / W emulsion. Polyglyceryl-2 dipolyhydroxystearate, polyglyceryl-3 diisostearate and squalane were mixed in proportion and stirred at 300 rpm in a constant temperature water bath at 60°C for 3 minutes until they were completely miscible. The O / W emulsion was used as the inner aqueous phase and was slowly added dropwise to the outer oil phase continuous phase containing the emulsifier. A secondary homogenization was performed at 4,000 rpm for 3 minutes to obtain a structurally stable O / W / O multiple emulsion system.

[0037] The mass percentage of each component is: polyglyceryl-10 laurate 2%, pullulan 3%, propylene glycol 1%, polyglyceryl-2 dipolyhydroxystearate 3.6%, polyglyceryl-3 diisostearate 0.4%, GTCC 14%, deionized water 32%, and squalane 44%.

[0038] [Example 2]

[0039] A viscous liquid of polyglyceryl-10 isostearate and GTCC were mixed in proportion and stirred at 300 rpm in a constant temperature water bath at 60°C for 3 minutes until completely miscible. Propylene glycol was simultaneously dissolved in deionized water. The stabilizer was fully dissolved under the same temperature conditions. The aqueous phase was slowly added to the oil phase system, first stirred at 300 rpm, then homogenized at 12,000 rpm at room temperature for 5 minutes. Pullulan was then added and homogenized under the same conditions for 2 minutes to obtain an O / W emulsion. Polyglyceryl-2 dipolyhydroxystearate, polyglyceryl-3 diisostearate, and squalane were mixed in proportion and stirred at 300 rpm in a constant temperature water bath at 60°C for 3 minutes until completely miscible. The O / W emulsion, as the inner aqueous phase, was slowly added dropwise to the outer oil continuous phase containing the emulsifier. A second homogenization was performed at 3,000 rpm for 4 minutes to obtain a structurally stable O / W / O multiple emulsion system.

[0040] The mass percentage of each component is: polyglyceryl-10 isostearate 3%, pullulan 2%, propylene glycol 1%, polyglyceryl-2 dipolyhydroxystearate 3.6%, polyglyceryl-3 diisostearate 0.4%, GTCC 12%, deionized water 25%, and squalane 53%.

[0041] [Example 3]

[0042] The viscous liquid of polyglyceryl-10 laurate and GTCC were mixed in proportion and stirred at 300 rpm in a constant temperature water bath at 60°C for 3 minutes until they were completely miscible. Pullulan and propylene glycol were simultaneously dissolved in deionized water. The stabilizer was fully dissolved under the same temperature conditions. The aqueous phase was slowly added to the oil phase system, first stirred at 300 rpm, and then homogenized at 12000 rpm at room temperature for 5 minutes to obtain an O / W emulsion. Polyglyceryl-2 dipolyhydroxystearate, polyglyceryl-3 diisostearate, beeswax and squalane were mixed in proportion and stirred at 300 rpm in a constant temperature water bath at 60°C for 3 minutes until they were completely miscible. The O / W emulsion was used as the inner aqueous phase and was slowly added dropwise to the outer oil phase continuous phase containing the emulsifier. A secondary homogenization was performed at 4000 rpm for 4 minutes to obtain a structurally stable O / W / O multiple emulsion system.

[0043] The mass percentage of each component is: polyglyceryl-10 laurate 3%, pullulan 2%, propylene glycol 1%, polyglyceryl-2 dipolyhydroxystearate 3.6%, polyglyceryl-3 diisostearate 0.4%, beeswax 4%, GTCC 13%, deionized water 31%, squalane 42%.

[0044] [Example 4]

[0045] The viscous liquid of polyglyceryl-10 laurate and GTCC were mixed in proportion and stirred at 300 rpm in a constant temperature water bath at 60°C for 3 minutes until they were completely miscible. Pullulan and propylene glycol were simultaneously dissolved in deionized water. The stabilizer was fully dissolved under the same temperature conditions. The aqueous phase was slowly added to the oil phase system, first stirred at 300 rpm, and then homogenized at 12000 rpm at room temperature for 5 minutes to obtain an O / W emulsion. Polyglyceryl-2 dipolyhydroxystearate, polyglyceryl-3 diisostearate, beeswax and squalane were mixed in proportion and stirred at 300 rpm in a constant temperature water bath at 60°C for 3 minutes until they were completely miscible. The O / W emulsion was used as the inner aqueous phase and was slowly added dropwise to the outer oil phase continuous phase containing the emulsifier. A second homogenization was performed at 3000 rpm for 4 minutes to obtain a structurally stable O / W / O multiple emulsion system.

[0046] The mass percentage of each component is: polyglyceryl-10 laurate 2%, pullulan 3%, propylene glycol 1%, polyglyceryl-2 dipolyhydroxystearate 3.6%, polyglyceryl-3 diisostearate 0.4%, beeswax 3%, GTCC 12%, deionized water 24%, squalane 51%.

[0047] [Comparative Example 1]

[0048] The polyglyceryl-10 palmitate block solid and GTCC were mixed in proportion, stirred at 300 rpm in a constant temperature water bath at 60°C for 3 minutes until they were completely dissolved. Pullulan and propylene glycol were simultaneously dissolved in deionized water, and the stabilizer was fully dissolved under the same temperature conditions. The aqueous phase was slowly added to the oil phase system, first stirred at 300 rpm, and then homogenized at 10,000 rpm at room temperature for 5 minutes to obtain an O / W emulsion; polyglyceryl-2 dipolyhydroxystearate, polyglyceryl-3 diisostearate and squalane were mixed in proportion, stirred at 300 rpm in a constant temperature water bath at 60°C for 3 minutes until they were completely dissolved, and then slowly added dropwise to the external oil phase continuous phase containing the emulsifier, and homogenized twice at 3000 rpm. The homogenization time was set to 4 minutes to obtain an O / W / O multiple emulsion.

[0049] The mass percentage of each component is: polyglyceryl-10 palmitate 2%, pullulan 3%, propylene glycol 1%, polyglyceryl-2 dipolyhydroxystearate 3.6%, polyglyceryl-3 diisostearate 0.4%, GTCC 14%, deionized water 32%, and squalane 44%.

[0050] The stability test showed that the multiple emulsion formed in Comparative Example 1 separated quickly due to the poor emulsification effect of polyglycerol-10 palmitate.

[0051] [Comparative Example 2]

[0052] The viscous liquid of polyglyceryl-10 laurate and GTCC were mixed in proportion, stirred at 300 rpm in a constant temperature water bath at 60°C for 3 minutes until they were completely miscible. Pullulan and propylene glycol were simultaneously dissolved in deionized water, and the stabilizer was fully dissolved under the same temperature conditions. The aqueous phase was slowly added to the oil phase system, first stirred at 300 rpm, and then homogenized at 10,000 rpm at room temperature for 5 minutes to obtain an O / W emulsion; polyglyceryl-2 dipolyhydroxystearate and squalane were mixed in proportion, stirred at 300 rpm in a constant temperature water bath at 60°C for 3 minutes until they were completely miscible. The O / W emulsion was used as the inner aqueous phase and slowly added dropwise to the outer oil phase continuous phase containing the emulsifier. The mixture was homogenized twice at 3000 rpm, and the homogenization time was set to 4 minutes to obtain an O / W / O multiple emulsion.

[0053] The mass percentage of each component is: polyglyceryl-10 laurate 2%, pullulan 3%, propylene glycol 1%, polyglyceryl-2 dipolyhydroxystearate 4%, GTCC 14%, deionized water 32%, and squalane 44%.

[0054] The stability test shows that the O / W / O multiple emulsion obtained in this comparative example has poor emulsification effect and poor stability due to the use of a single emulsifier on the outer interface.

[0055] [Comparative Example 3]

[0056] The viscous liquid of polyglyceryl-10 laurate and GTCC were mixed in proportion, stirred at 300 rpm in a constant temperature water bath at 60°C for 3 minutes until they were completely miscible. Pullulan and propylene glycol were simultaneously dissolved in deionized water, and the stabilizer was fully dissolved under the same temperature conditions. The aqueous phase was slowly added to the oil phase system, first stirred at 300 rpm, and then homogenized at 10,000 rpm at room temperature for 5 minutes to obtain an O / W emulsion. Polyglyceryl-2 dipolyhydroxystearate, polyglyceryl-3 diisostearate and squalane were mixed in proportion, stirred at 300 rpm in a constant temperature water bath at 60°C for 3 minutes until they were completely miscible. The O / W emulsion was used as the inner aqueous phase and was slowly added dropwise to the outer oil phase continuous phase containing the emulsifier. A secondary homogenization was performed at 3000 rpm, and the homogenization time was set to 8 minutes to obtain a mixed emulsion of ordinary O / W emulsion and W / O emulsion.

[0057] The mass percentage of each component is: polyglyceryl-10 laurate 2%, pullulan 3%, propylene glycol 1%, polyglyceryl-2 dipolyhydroxystearate 3.6%, polyglyceryl-3 diisostearate 0.4%, GTCC 14%, deionized water 32%, and squalane 44%.

[0058] Microscopic observation showed that the above phenomenon occurred because the homogenization time was too long during the second homogenization, which destroyed the O / W / O multiple emulsion structure.

[0059] [Comparative Example 4]

[0060] The viscous liquid of polyglyceryl-10 laurate and isopropyl myristate were mixed in proportion, stirred at 300 rpm in a constant temperature water bath at 60°C for 3 minutes until they were completely dissolved in each other. Pullulan and propylene glycol were simultaneously dissolved in deionized water, and the stabilizer was fully dissolved under the same temperature conditions. The aqueous phase was slowly added to the oil phase system, first stirred at 300 rpm, and then homogenized at 10,000 rpm at room temperature for 5 minutes to obtain an O / W emulsion. Polyglyceryl-2 dipolyhydroxystearate, polyglyceryl-3 diisostearate and squalane were mixed in proportion, stirred at 300 rpm in a constant temperature water bath at 60°C for 3 minutes until they were completely dissolved in each other. The O / W emulsion was used as the inner aqueous phase and was slowly added dropwise to the outer oil phase continuous phase containing the emulsifier. The mixture was homogenized twice at 3000 rpm, and the homogenization time was set to 8 minutes to obtain a mixed emulsion of ordinary O / W emulsion and W / O emulsion.

[0061] The mass percentage of each component is: polyglyceryl-10 laurate 2%, pullulan 3%, propylene glycol 1%, polyglyceryl-2 dipolyhydroxystearate 3.6%, polyglyceryl-3 diisostearate 0.4%, isopropyl myristate 14%, deionized water 32%, and squalane 44%.

[0062] Microscopic observation revealed that the aforementioned phenomenon occurred because the polarity of the inner oil phase, isopropyl myristate, was higher than that of the outer oil phase, squalane. This resulted in an excessively high polarity of the inner oil phase in the multiple emulsion system, causing phase separation of the O / W emulsion and ultimately preventing the formation of an O / W / O multiple emulsion.

[0063]

Microstructure Analysis

[0064] A certain amount of the emulsion prepared in Example 1 of the present invention was taken and placed on a glass slide. The structure and particle size of the emulsion were observed using an optical microscope (Lx POL polarizing microscope from LAMOMED, ​​USA). The results are as follows: Figure 1 As shown. Figure 1 It can be clearly seen that the O / W / O multiple emulsion droplet size ranges from 1 to 20 μm, and each droplet contains one or more oil droplets separated by an aqueous phase, forming a stable O / W / O multiple emulsion structure. The O / W / O multiple emulsions prepared in Examples 2 to 4 also exhibited similar microstructures under a microscope and will not be further described here.

[0065]

Stability test

[0066] The stability of the O / W / O multiple emulsions prepared in the examples of the present invention will be further described in detail below through stability tests.

[0067] High temperature stability: Transfer 5 mL of the emulsion into a glass bottle, seal it, and store it in a 45°C oven for 7 days to observe whether the emulsion separates.

[0068] Low temperature stability: Transfer 5 mL of the emulsion into a glass bottle, seal it, and store it in a -10°C refrigerator for 7 days. Observe whether the emulsion separates into layers.

[0069] Centrifugal stability: Take an appropriate amount of emulsion and place it in a centrifuge tube. Centrifuge at 3000r / min for 30min and observe whether the emulsion is stratified.

[0070] The test results are shown in Table 1.

[0071] Table 1 Physical and chemical index test results of O / W / O multiple emulsions

[0072]

[0073] Note: "+" in the table indicates the degree of stability, and "-" indicates that no multiple emulsion system is formed

[0074] As can be seen from Table 1, the multiple emulsion prepared by the present invention is milky white, opaque, fine in texture, and uniform, indicating that the appearance and properties of the emulsion meet the standard requirements. It remains unstratified for 7 days under high temperature conditions of 40°C ± 1°C, remains unstratified for 7 days under low temperature conditions of -8°C ± 2°C, and does not stratify under high-speed centrifugation conditions, indicating that the heat resistance, cold resistance, and centrifugal stability of the emulsion of the present invention meet the standard requirements and have excellent performance. However, the heat resistance, cold resistance, and stability of the emulsions prepared in Comparative Examples 1 and 2 do not meet the requirements of skin care emulsions and cannot meet the stability requirements of skin care emulsions. The emulsions prepared in Comparative Examples 3 and 4 were unable to form multiple emulsions, so stability tests were not performed.

Claims

1. A polyglycerol fatty acid ester O / W / O type multiple emulsion, which is prepared by mixing an O / W emulsion with an outer oil phase and then subjecting it to secondary emulsification, characterized in that: First, oil A, deionized water, emulsifier I, pullulan, and stabilizer are mixed in a mass ratio of (8-15):(28-40):(0.5-3):(0.5-5):(1-5) and emulsified to obtain an O / W emulsion; then, emulsifier II, beeswax, and liquid oil B are uniformly mixed in a mass ratio of (2-6):(1-5):(40-55) to obtain an outer oil phase; finally, the O / W emulsion and the outer oil phase are mixed in a mass ratio of 4:6-5:5 and emulsified twice to obtain the polyglycerol fatty acid ester O / W / O type multiple emulsion.

2. The polyglycerol fatty acid ester O / W / O type multiple emulsion according to claim 1, wherein: The liquid oil A is one or more of caprylic / capric triglyceride, isopropyl myristate, isopropyl palmitate, and ethyl palmitate.

3. The polyglycerol fatty acid ester O / W / O type multiple emulsion according to claim 1, wherein: The emulsifier I is any one of polyglyceryl-10 laurate, polyglyceryl-10 myristate, polyglyceryl-10 palmitate, polyglyceryl-10 stearate, polyglyceryl-10 oleate, and polyglyceryl-10 isostearate.

4. The polyglycerol fatty acid ester O / W / O type multiple emulsion according to claim 1, wherein: The stabilizer is one or more of glycerol, butylene glycol, propylene glycol, 1,3-butylene glycol, and 1,3-propylene glycol.

5. The polyglycerol fatty acid ester O / W / O type multiple emulsion according to claim 1, wherein: The emulsifier II is one or more of polyglyceryl-3 polyricinoleate, polyglyceryl-3 diisostearate, and polyglyceryl-2 dipolyhydroxystearate.

6. The polyglycerol fatty acid ester O / W / O type multiple emulsion according to claim 1, wherein: The liquid oil B is one or more of octane, dodecane, hexadecane and squalane.

7. A method for preparing the polyglycerol fatty acid ester O / W / O type multiple emulsion according to claims 1 to 6, comprising the following steps: (1) Emulsifier I and liquid oil A are mixed in proportion and heated in a water bath to obtain an oil phase; a stabilizer and pullulan are added to deionized water in proportion to obtain an aqueous phase; the oil phase and the aqueous phase are mixed and emulsified in a mass ratio of 2:8 to 3:7 to obtain an O / W emulsion; (2) Emulsifier II, beeswax, and liquid oil B were mixed in proportion and stirred at a rate of 200-400 rpm in a constant temperature water bath at 60°C until they were completely miscible to obtain an external oil phase; (3) adding the O / W emulsion to the external oil phase in a mass ratio of 4:6 to 5:5 to perform secondary emulsification to obtain the polyglycerol fatty acid ester O / W / O type multiple emulsion.

8. The method for preparing a polyglycerol fatty acid ester O / W / O type multiple emulsion according to claim 7, wherein: The steps of mixing the oil phase and the water phase for emulsification are as follows: slowly adding the oil phase to the water phase, and high-speed shear homogenizing mixing at a shear rate of 10,000-12,000 rpm for 5-8 minutes at a water bath temperature of 60-90° C. to obtain an O / W emulsion.

9. The method for preparing a polyglycerol fatty acid ester O / W / O type multiple emulsion according to claim 7, wherein: The step of adding the O / W emulsion to the external oil phase for secondary emulsification is as follows: slowly adding the O / W emulsion dropwise to the external oil phase, and performing low-speed shear homogenization mixing at a shear rate of 3000-6000 rpm at a water bath temperature of 60-90° C. for 3-5 minutes to obtain a structurally stable O / W / O multiple emulsion system.

10. Use of the polyglycerol fatty acid ester O / W / O type multiple emulsion according to any one of claims 1 to 6 as a skin care product or a skin care product additive.

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