Three-layered milk cover essence and preparation method thereof

Abstract

The application discloses a three-layer milk cover essence and a preparation method thereof. The essence has a three-layer structure in a stable state, wherein an upper layer is a lotion phase, a middle layer is a water phase, and a lower layer is an oil phase. The essence comprises, by weight, 55-90 parts of water, 0.5-6.5 parts of a humectant, 0.3-2 parts of an emulsifier, 0.1-2.3 parts of sodium chloride, 12-30 parts of a skin moisturizer A, 10-35 parts of a skin moisturizer B, 0.01-0.15 parts of a liquorice root extract and 0.3-3 parts of a preservative. The humectant comprises 1,3-propanediol, butanediol, 1,2-pentanediol and glycerol. The emulsifier comprises inulin lauryl carbamate. The three-layer milk cover essence has the advantages that the water phase is not easy to become turbid, the boundary of the layered part is clear, no discontinuous feeling and greasy feeling of oil-water separation occurs during smearing, good skin affinity and moisturizing effect are achieved, the lotion phase, the water phase and the oil phase can stably coexist, and the essence can automatically restore to the original state after being shaken.

Description

Technical Field

[0001] This invention relates to the field of multi-layer essence technology, and in particular to a three-layer milk foam essence and its preparation method. Background Technology

[0002] In the field of functional skincare technology, multi-phase serums have gradually become a research hotspot in order to address the issues of greasiness and slow absorption in single-oil products, while also ensuring the stability and delivery efficiency of active ingredients. These products typically utilize the layered structure formed by immiscible aqueous and oil phases under natural static conditions. By shaking the product before use, the water and oil are mixed to achieve a skincare effect that is both moisturizing and relatively refreshing.

[0003] However, multi-layered serums containing lotion commonly found on the market still have many shortcomings, mainly in the following aspects:

[0004] 1. Poor emulsion stability, prone to oil-water separation. Multi-layered skincare products containing emulsion layers are prone to gradual phase separation during storage: the oil phase rises and precipitates, the water phase becomes cloudy, the interface becomes blurred, and even the boundary between layers disappears. On the one hand, this can be felt as a discontinuous feeling of oil-water separation and greasiness when applying the product, and on the other hand, it seriously affects the product's shelf stability and consumer perception.

[0005] II. Three-layer serums consisting of emulsion, water phase, and oil phase are difficult to prepare. Most multi-layered skincare products on the market that include emulsion are essentially two-phase (oil / water) bilayer structures. For example, some products called "milk foam water" or "rejuvenating double brightening essence water" have a milky-white upper layer, but are essentially a light oil layer with a trace amount of emulsifier, primarily composed of an oil phase. The lower layer is a transparent water phase, consisting of only two layers, and the boundaries easily become cloudy and indistinct over time. In the production of multi-layered serums, a combination of emulsion and oil phase is generally not used. This is because the density and rheological properties of the emulsion differ significantly from those of the oil phase, and the choice of emulsifier often struggles to balance the "small particle size of the emulsion" with the "long-term clarity of the interlayer interface." To stabilize the emulsion, excessive amounts of high-molecular-weight thickeners are often introduced. These components diffuse through the phase interface, damaging the color purity and stability of the oil phase, resulting in the product not automatically returning to its original state after shaking and standing, or taking a long time to recover. Some people have tried to create a multi-layered serum containing emulsion, water phase and oil phase, but the emulsion layer is almost a pure oil layer. The three layers of serum with emulsion, water phase and oil phase are difficult to coexist stably and it is difficult to obtain a milk foam-like three-layer serum.

[0006] Therefore, existing multi-layered serums containing emulsions are prone to cloudiness in the aqueous phase, with unclear boundaries between the layers; they also have a discontinuous feeling of oil-water separation and greasiness when applied; the emulsion, aqueous phase, and oil phase are difficult to coexist stably, and are difficult to restore to their original state after shaking. Summary of the Invention

[0007] The purpose of this invention is to provide a three-layer milk foam essence and its preparation method. The three-layer milk foam essence of this invention exhibits a water phase that is not easily clouded, with clear boundaries between the layers; it avoids the discontinuous feeling and greasiness of oil-water separation during application, and possesses excellent skin affinity and moisturizing effects; the three layers—lotion, water phase, and oil phase—can coexist stably and automatically return to their original state after shaking.

[0008] The technical solution of this invention: a three-layer milk foam essence, wherein the essence has a three-layer structure in a stable state, with an upper emulsion phase, a middle aqueous phase, and a lower oil phase. The essence, by weight, comprises 55-90 parts water, 0.5-6.5 parts moisturizer, 0.3-2 parts emulsifier, 0.1-2.3 parts sodium chloride, 12-30 parts skin moisturizer A, 10-35 parts skin moisturizer B, 0.01-0.15 parts purple gromwell root extract, and 0.3-3 parts preservative. The moisturizer includes 1,3-propanediol, butylene glycol, 1,2-pentanediol, and glycerin; the emulsifier includes inulin lauryl carbamate; skin moisturizer A includes neopentyl glycol di(ethylhexanoate), squalane, and caprylic / capric triglyceride; skin moisturizer B includes trimethylpentaphenyltrisiloxane; and the preservative includes phenoxyethanol, ethylhexylglycerin, and caprylyl glycol. The three-layer milk foam essence formula has a pink emulsion on top, forming a milk foam-like texture; a colorless and transparent aqueous phase in the middle; and a colorless and transparent oil phase at the bottom. The colors are distinct, and the layers are clearly defined. The emulsion will not separate into oil and water, and it is not prone to flocculation, separation, or collapse. The aqueous phase is not easily cloudy, and the transparency of the oil phase is not easily compromised, resulting in good stability. After shaking, the three layers can be evenly mixed. When applied, there is no feeling of oil-water separation, discontinuity, or greasiness. This solves the discomfort and greasiness caused by oil-water separation in pure oil-based or multi-layered water-oil formulations, and has a good skin-friendly and moisturizing effect. The emulsion phase, aqueous phase, and oil phase can coexist stably, and they will automatically return to their original state after being shaken and left to stand.

[0009] The aforementioned three-layer milk foam essence, by weight, includes 61-82 parts water, 1-5.5 parts moisturizer, 0.45-1.5 parts emulsifier, 0.2-2 parts sodium chloride, 15-27 parts skin moisturizer A, 20-30 parts skin moisturizer B, 0.02-0.1 parts colorant, and 1.5-3 parts preservative.

[0010] In the aforementioned three-layer milk foam essence, the mass ratio of the upper layer: middle layer: lower layer is (1-3): (4-7): (2-3).

[0011] In the aforementioned three-layer milk foam essence, the moisturizing agent includes 0.1-1 parts of 1,3-propanediol, 0.2-2 parts of butylene glycol, 0.1-1 parts of 1,2-pentanediol, and 0.75-1.5 parts of glycerin.

[0012] In the aforementioned three-layer milk foam essence, the emulsifiers also include sucrose stearate, polyglycerol-6-distearate, and glyceryl stearate citrate; the HLB of the glyceryl stearate citrate is 13-16; by weight, inulin lauryl carbamate 0.25-0.5 parts, sucrose stearate 0.05-0.3 parts, polyglycerol-6-distearate 0.1-0.5 parts, and glyceryl stearate citrate 0.05-0.2 parts. The synergistic effect of the compound emulsifiers can further improve the stability of the three-layer milk foam essence, significantly reduce the particle size of the emulsion, and exhibit better absorption and skin affinity when applied to the skin after shaking. Specifically: (1) Inulin lauryl carbamate constructs a strong interfacial membrane skeleton, and sucrose stearate, as a small molecule, can quickly embed into the gaps in the skeleton to form a densely packed composite interfacial membrane. Polyglycerol-6 distearate is stably bound to the oil droplets in the emulsion by the distearate chain and forms intermolecular hydrogen bonds with the hydroxyl groups of inulin polysaccharide by the polyglycerol chain, which are firmly bound to the backbone structure. The three work together to make the interface film strong and stable; (2) The citric acid residue of glycerol stearate citrate dissociates into -COO⁻, which gives the surface of the oil droplets a negative charge and generates strong electrostatic repulsion between the oil droplets. Electrostatic repulsion and a stable and firm interface film can prevent droplet aggregation, significantly enhance the stability of the emulsion, and the emulsion, water phase, and oil phase coexist stably; (3) Sucrose stearate has a diffusion rate far exceeding that of the high molecular weight emulsifier. It reaches the newly formed oil-water interface instantly after shaking, which significantly reduces the interfacial tension, promotes the rapid breakup of the oil phase into small droplets, and significantly reduces the particle size. This increases the specific surface area of ​​the emulsion in contact with the skin, significantly improves the absorption efficiency of the effective ingredients in the three-layer milk cap essence, and at the same time, the strong and stable interface film can prevent the process of small oil droplet dissolution and large oil droplet growth, ensuring long-term stability of the particle size.

[0013] In the aforementioned three-layer milk foam essence, the emollient A includes 15-25 parts of neopentyl glycol di(ethylhexanoate), 0.1-1 parts of squalane, and 0.08-0.4 parts of caprylic / capric triglyceride; and / or; the emollient B includes 20-30 parts of trimethylpentaphenyltrisiloxane.

[0014] In the aforementioned three-layer milk foam essence, the preservatives include 0.45-0.9 parts of phenoxyethanol, 0.35-0.7 parts of ethylhexylglycerin, and 0.7-1.4 parts of caprylyl glycol.

[0015] The aforementioned method for preparing the three-layer milk foam essence includes the following steps:

[0016] Step a: Add water, humectant, emulsifier, and sodium chloride to the reaction vessel, heat and stir to obtain product A;

[0017] Step b: Add emollient A, colorant, and preservative to the reaction vessel, heat and stir to obtain product B;

[0018] Step c: Mix product A and product B, homogenize at 70-90℃ and 2500-5000 r / min for 15-35 min, then homogenize at 1500-2500 r / min until cooled to room temperature to obtain product C.

[0019] Step d: Filter product C to obtain product D;

[0020] Step e: Fill product D and moisturizer B in separate steps. First fill moisturizer B, then fill product D. The mass ratio of product D to moisturizer B is (7-8):(2-3). Let stand to obtain the finished product.

[0021] In the aforementioned method for preparing the three-layer milk foam essence, in step a, the temperature is heated to 50-85℃ and the stirring speed is 15-50 r / min.

[0022] In the aforementioned method for preparing the three-layer milk foam essence, in step b, the temperature is heated to 50-85℃ and the stirring speed is 15-50 r / min.

[0023] Compared with existing technologies, this invention, through extensive screening experiments, identified an emulsifier containing inulin lauryl carbamate and selected suitable moisturizers, emollients, and preservatives. An appropriate amount of sodium chloride was used to adjust the density of the essence, forming a clearly defined three-layer structure: an upper pink emulsion with a milky foam-like appearance, a middle colorless and transparent aqueous phase, and a bottom colorless and transparent oil phase. After shaking, it can be used as a spray or topical skincare product. The essence formula significantly improves the stability of the essence, prevents oil-water separation, and exhibits excellent skin affinity and absorption when applied to the skin after shaking. Furthermore, it automatically restores its three-layer structure after shaking. This invention's three-layer milky foam essence does not easily become cloudy in the aqueous phase, and the boundaries between the layers are clear. When applied, it avoids the discontinuous feeling and greasiness associated with oil-water separation, providing excellent skin affinity and moisturizing effects. The emulsion, aqueous phase, and oil phase can coexist stably and automatically return to their original state after shaking. Detailed Implementation

[0024] The present invention will be further described below with reference to the embodiments. These embodiments are purely illustrative and are only used to describe the present invention, and are not intended to limit the present invention.

[0025] Example 1. A three-layer milk foam essence, wherein the essence has a three-layer structure in a stable state, with an upper emulsion phase, a middle aqueous phase, and a lower oil phase, the mass ratio of upper layer:middle layer:lower layer is 1.6:4:2.2, and by weight includes 55 parts water; 0.5 parts moisturizer, wherein the moisturizer is 0.1 parts 1,3-propanediol, 0.2 parts butylene glycol, 0.1 parts 1,2-pentanediol, and 0.1 parts glycerin; 0.3 parts inulin lauryl carbamate (INUTEC SL1, LABORATOIRES SETHIC INNOVATIONS); 0.1 parts sodium chloride; 12 parts emollient A, wherein emollient A is 11.7 parts neopentyl glycol di(ethylhexanoate), 0.2 parts squalane, and 0.1 parts caprylic / capric triglyceride (MYRITOL 318 RC, BASF (China) Co., Ltd.); emollient B 10 parts of trimethylpentaphenyltrisiloxane, 0.01 parts of Lithospermum erythrorhizon root extract (oil-soluble Lithospermum erythrorhizon extract-G&I, Guangzhou Luojie Biotechnology Co., Ltd.), and 0.3 parts of preservatives, including 0.2 parts of phenoxyethanol, 0.05 parts of ethylhexylglycerin, and 0.05 parts of caprylyl glycol.

[0026] The preparation method of the three-layer milk foam essence includes the following steps:

[0027] Step a: Add water, humectant, emulsifier, and sodium chloride to the reaction vessel, heat to 50°C, and stir at 15 r / min for 90 min to obtain product A;

[0028] Step b: Add emollient A, colorant and preservative into the reaction vessel, heat to 50°C, and stir at 15 r / min for 90 min to obtain product B;

[0029] Step c: Mix product A and product B, homogenize at 70°C and 2500 r / min for 35 min, then homogenize at 1500 r / min until cooled to room temperature to obtain product C;

[0030] Step d: Filter product C to obtain product D;

[0031] Step e: Fill product D and moisturizer B separately, first filling moisturizer B and then filling product D. The mass ratio of product D to moisturizer B is 7:3. Let stand to obtain the finished product.

[0032] Example 2. The three-layer milk foam essence has a three-layer structure in a stable state: an upper emulsion phase, a middle aqueous phase, and a lower oil phase, with a mass ratio of upper:middle:lower layer of 2.6:4:2. By weight, it includes 90 parts water; 6.5 parts moisturizer, which consists of 2 parts 1,3-propanediol, 2 parts butylene glycol, 1 part 1,2-pentanediol, and 1.5 parts glycerin; 2 parts inulin lauryl carbamate; 2.3 parts sodium chloride; 30 parts emollient A, which consists of 26 parts neopentyl glycol di(ethylhexanoate), 3.5 parts squalane, and 0.5 parts caprylic / capric triglyceride; 35 parts emollient B trimethylpentaphenyltrisiloxane; 0.15 parts comfrey root extract; and 3 parts preservative, which consists of 0.9 parts phenoxyethanol, 0.7 parts ethylhexylglycerin, and 1.4 parts caprylyl glycol.

[0033] The preparation method of the three-layer milk foam essence includes the following steps:

[0034] Step a: Add water, humectant, emulsifier, and sodium chloride to the reaction vessel, heat to 85°C, and stir at 50 r / min for 30 min to obtain product A;

[0035] Step b: Add emollient A, colorant and preservative into the reaction vessel, heat to 85°C, and stir at 50 r / min for 30 min to obtain product B;

[0036] Step c: Mix product A and product B, homogenize at 90°C and 5000 r / min for 15 min, then homogenize at 2500 r / min until cooled to room temperature to obtain product C;

[0037] Step d: Filter product C to obtain product D;

[0038] Step e: Fill product D and moisturizer B separately, first filling moisturizer B and then filling product D. The mass ratio of product D to moisturizer B is 8:2. Let stand to obtain the finished product.

[0039] Example 3. A three-layer milk foam essence, wherein the essence has a three-layer structure in a stable state, with an upper emulsion phase, a middle aqueous phase, and a lower oil phase, and a mass ratio of upper:middle:lower layer of 3:4.2:2. By weight, it includes 62.5 parts of water, 1.15 parts of moisturizer, wherein the moisturizer is 0.1 parts of 1,3-propanediol, 0.2 parts of butylene glycol, 0.1 parts of 1,2-pentanediol, and 0.75 parts of glycerin, and 0.45 parts of emulsifier, wherein the emulsifier is 0.25 parts of inulin lauryl carbamate, 0.05 parts of sucrose stearate (BINEMULSO SSE, Shanghai Zibang Biopharmaceutical Co., Ltd.), 0.1 parts of polyglycerol-6 distearate (UN-177, Foshan Yinmei United Technology Co., Ltd.), and glyceryl stearate citrate (KRownCos EmulKreg GSC, Kreglinger Europe). NV) 0.05 parts, wherein the HLB of the sucrose stearate is 15, sodium chloride 0.2 parts, emollient A 15.18 parts, wherein emollient A is neopentyl glycol di(ethylhexanoate) ester 15 parts, squalane 0.1 parts, caprylic / capric triglyceride 0.08 parts, emollient B trimethylpentaphenyltrisiloxane 20 parts, comfrey root extract 0.02 parts, preservative 1.5 parts, wherein the preservative is phenoxyethanol 0.45 parts, ethylhexylglycerin 0.35 parts, caprylyl glycol 0.7 parts.

[0040] The preparation method of the three-layer milk foam essence includes the following steps:

[0041] Step a: Add water, humectant, emulsifier, and sodium chloride to the reaction vessel, heat to 65°C, and stir at 30 r / min for 60 min to obtain product A;

[0042] Step b: Add emollient A, colorant and preservative into the reaction vessel, heat to 70°C, stir at 30 r / min for 30 min to obtain product B;

[0043] Step c: Mix product A and product B, homogenize at 3500 r / min for 20 min at 80℃, and then homogenize at 2000 r / min until cooled to room temperature to obtain product C;

[0044] Step d: Filter product C to obtain product D;

[0045] Step e: Fill product D and moisturizer B separately, first filling moisturizer B and then filling product D. The mass ratio of product D to moisturizer B is 7:3. Let stand to obtain the finished product.

[0046] Example 4. A three-layer milk foam essence, wherein the essence has a three-layer structure in a stable state, with an upper emulsion phase, a middle aqueous phase, and a lower oil phase, the mass ratio of upper layer:middle layer:lower layer is 2.8:6.5:3. By weight, it includes 81.7 parts water, 5.5 parts moisturizer, wherein the moisturizer is 1 part 1,3-propanediol, 2 parts butylene glycol, 1 part 1,2-pentanediol, and 1.5 parts glycerin, 1.5 parts emulsifier, wherein the emulsifier is 0.5 parts inulin lauryl carbamate, 0.3 parts sucrose stearate, 0.5 parts polyglycerol-6 distearate, and 0.2 parts glyceryl stearate citrate, wherein the sucrose stearate has an HLB of 16, 2 parts sodium chloride, and emollient A. 26 parts, wherein the emollient A is 25 parts neopentyl glycol di(ethylhexanoate), 0.6 parts squalane, and 0.4 parts caprylic / capric triglyceride; emollient B is 30 parts trimethylpentaphenyltrisiloxane, 0.1 parts Lithospermum erythrorhizon root extract; and 3 parts preservative, wherein the preservative is 0.9 parts phenoxyethanol, 0.7 parts ethylhexylglycerin, and 1.4 parts caprylyl glycol.

[0047] The preparation method of the three-layer milk foam essence includes the following steps:

[0048] Step a: Add water, humectant, emulsifier, and sodium chloride to the reaction vessel, heat to 65°C, and stir at 30 r / min for 60 min to obtain product A;

[0049] Step b: Add emollient A, colorant and preservative into the reaction vessel, heat to 70°C, stir at 30 r / min for 30 min to obtain product B;

[0050] Step c: Mix product A and product B, homogenize at 3500 r / min for 20 min at 80℃, and then homogenize at 2000 r / min until cooled to room temperature to obtain product C;

[0051] Step d: Filter product C to obtain product D;

[0052] Step e: Fill product D and moisturizer B separately, first filling moisturizer B and then filling product D. The mass ratio of product D to moisturizer B is 7:3. Let stand to obtain the finished product.

[0053] Example 5. A three-layer milk foam essence, wherein the essence has a three-layer structure in a stable state, with an upper emulsion phase, a middle aqueous phase, and a lower oil phase, the mass ratio of upper layer:middle layer:lower layer is 2.6:4.5:2. By weight, it includes 70 parts water, 3.5 parts moisturizer, the moisturizer comprising 0.5 parts 1,3-propanediol, 1 part butylene glycol, 0.5 parts 1,2-pentanediol, 1.5 parts glycerin, 1.2 parts emulsifier, the emulsifier being 0.35 parts inulin lauryl carbamate, 0.2 parts sucrose stearate, 0.3 parts polyglycerol-6 distearate, 0.15 parts glyceryl stearate citrate, the sucrose stearate having an HLB of 15, 1.2 parts sodium chloride, and emollient A. 20.7 parts, wherein the emollient A is 20 parts neopentyl glycol di(ethylhexanoate), 0.5 parts squalane, and 0.2 parts caprylic / capric triglyceride; the emollient B is 25 parts trimethylpentaphenyltrisiloxane, and 0.5 parts comfrey root extract; and the preservative is 2.1 parts phenoxyethanol, 0.6 parts ethylhexylglycerin, and 1 part caprylyl glycol.

[0054] The preparation method of the three-layer milk foam essence includes the following steps:

[0055] Step a: Add water, humectant, emulsifier, and sodium chloride to the reaction vessel, heat to 65°C, and stir at 30 r / min for 60 min to obtain product A;

[0056] Step b: Add emollient A, colorant and preservative into the reaction vessel, heat to 70°C, and stir at 30 r / min for 60 min to obtain product B;

[0057] Step c: Mix product A and product B, homogenize at 3500 r / min for 20 min at 80℃, and then homogenize at 2000 r / min until cooled to room temperature to obtain product C;

[0058] Step d: Filter product C to obtain product D;

[0059] Step e: Fill product D and moisturizer B separately, first filling moisturizer B and then filling product D. The mass ratio of product D to moisturizer B is 7:3. Let stand to obtain the finished product.

[0060] Comparative Example 1. Essence. The difference between the formulation of this invention and Example 5 is that the three-layer milk foam essence contains 0.65 parts of emulsifier, which is 0.2 parts of sucrose stearate, 0.3 parts of polyglycerol-6 distearate, and 0.15 parts of glyceryl stearate citrate. The HLB of the sucrose stearate is 15. The preparation method is the same as in Example 5.

[0061] Comparative Example 2. Essence. By weight, it comprises 50 parts water; 0.3 parts moisturizer, which is 0.1 parts 1,3-propanediol, 0.05 parts butylene glycol, 0.05 parts 1,2-pentanediol, and 0.1 parts glycerin; 0.2 parts inulin lauryl carbamate; 0.06 parts sodium chloride; 8 parts emollient A, which is 6 parts neopentyl glycol di(ethylhexanoate), 1 part squalane, and 1 part caprylic / capric triglyceride; 7 parts emollient B trimethylpentaphenyltrisiloxane; 0.01 parts comfrey root extract; and 0.3 parts preservative, which includes 0.2 parts phenoxyethanol, 0.05 parts ethylhexylglycerin, and 0.05 parts caprylyl glycol. The preparation method is the same as in Example 5.

[0062] Comparative Example 3. Essence. By weight, it includes 100 parts water; 8 parts moisturizer, which is 2 parts 1,3-propanediol, 2 parts butylene glycol, 2 parts 1,2-pentanediol, and 2 parts glycerin; 3 parts inulin lauryl carbamate; 3 parts sodium chloride; 35 parts emollient A, which is 26 parts neopentyl glycol di(ethylhexanoate), 6.5 parts squalane, and 2.5 parts caprylic / capric triglyceride; 40 parts emollient B trimethylpentaphenyltrisiloxane; 0.15 parts comfrey root extract; and 3 parts preservative, which is 0.9 parts phenoxyethanol, 0.7 parts ethylhexylglycerin, and 1.4 parts caprylyl glycol. The preparation method is the same as in Example 5.

[0063] Performance testing. The performance of the three-layer milk foam essences prepared in Examples 1-5 and the essences prepared in Comparative Examples 1-3 was tested. Before sampling, the samples to be tested were shaken well for 5 minutes.

[0064] Stability test: The sample to be tested was filled into a 250mL transparent frosted reagent bottle, capped, and left to stand at a temperature of 25±2℃ and a relative humidity of 60%±5%. The layering and state of each layer of the product were observed and recorded at 24 hours, 7 days, 30 days, 90 days, and 180 days after preparation. The test results are shown in Table 1.

[0065] Three-layer structure auto-recovery time test: Take 30mL of the sample to be tested and place it in a 50mL stoppered graduated cylinder. Place it in a constant temperature environment of 25±2℃ and let it stand for 1 day. Record the height of each layer. Shake 30 times to fully mix the three layers until the three layers are completely restored to their initial layered state. Record the time required for complete recovery and the height of each layer after recovery. At the same time, observe whether the interface of each layer is clear and flat. The test results are shown in Table 2.

[0066] Emulsion droplet size detection: Take 30 mL of the sample to be tested and place it in a 50 mL stoppered graduated cylinder. Place it in a constant temperature environment of 25±2℃ and let it stand for 1 h. Add water to 30 mL of the upper emulsion and stir gently to disperse it evenly. Measure it by laser diffraction. Measurement conditions: stirring speed 2000 rpm. Detect each sample 3 times. The test results are shown in Table 3.

[0067] Moisturizing effect test: 24 healthy female volunteers aged 20-45 years were selected and divided into groups of 3. The inner forearm was used as the test area, and the stratum corneum moisture content was measured between 15-45. No products (including cosmetics and topical medications) were used on the test area for 3 days prior to the test. After cleansing the skin, the volunteers sat quietly for 30 minutes in a constant temperature and humidity environment (temperature 22±1℃, relative humidity 50%±5%), without drinking water or beverages. The test area was exposed, and the volunteers remained relaxed. The baseline skin moisture value of the test area was measured. Approximately 0.02g of the sample was evenly applied to a 2cm×4cm area. The stratum corneum moisture content was measured using a Corneometer CM825 skin moisture meter at 0.5h, 1h, 2h, 4h, 6h, and 8h after application. Each time point was measured three times, and the average value was taken. The results are shown in Table 4.

[0068] Skin feel test: A sensory evaluation group (40 people, aged 20-35, female, 5 people per group) was formed. 0.04g of the test sample (using Cetaphil moisturizing lotion as a control) was applied to a 4cm×4cm area on the back of the hand and spread in a circular motion until absorbed. The following indicators were evaluated (1-10 points, 10 points being the best). The test results are shown in Table 5.

[0069] (1) Spreadability: The degree to which the product spreads evenly on the skin when applied;

[0070] (2) Absorption rate: The speed at which the product is absorbed from application;

[0071] (3) Freshness: The degree to which the product feels fresh and non-greasy after application;

[0072] (4) Moisturizing sensation: The degree of moisturization after application to the skin;

[0073] (5) Overall satisfaction: Overall satisfaction with the user experience.

[0074] Table 1 Stability test results

[0075]

[0076] As shown in Table 1, the three-layer milk foam essences prepared in Examples 1-5 maintained their three-layer structure during the 180-day observation period. Examples 3-5 exhibited excellent long-term stability, with clear boundaries, smooth interfaces, and no changes throughout the entire 180-day observation period, demonstrating the superior effect of the compound emulsifier. In Example 1, the aqueous phase was turbid and the interface was slightly blurred at 180 days, but the three-layer structure was still visible, and no oil-water separation occurred, meeting the product usage requirements. In Example 2, the aqueous phase was slightly turbid at 180 days, but the boundaries of the three layers remained clear, with no oil-water separation, indicating good stability. Comparative Example 1 failed to form a three-layer structure, Comparative Example 2 experienced oil-water separation on day 7, and Comparative Example 3 showed a destroyed three-layer structure and disappearance of the interface on day 30. The three layers in the comparative examples could not maintain a stable structure.

[0077] Table 2. Results of Automatic Recovery Time Detection for Three-Layer Structure

[0078]

[0079] As shown in Table 2, the three-layer milk foam essences prepared in Examples 1-5 could automatically recover their three-layer structure after shaking. Examples 3-5 had the shortest recovery time (68-85 min), with small volume deviations in each layer after recovery (top layer ≤ +1.8%, middle layer ≥ -1.2%, bottom layer ≥ -0.6%), and clear, smooth interfaces. The strong interfacial film formed by the compound emulsifier and the electrostatic repulsion effect enabled the essence to quickly recover its layered structure. Example 1 had the longest recovery time (146 min) and a relatively large volume deviation (top layer +3.5%, middle layer -2.8%), but it was still within an acceptable range and could automatically recover after shaking. Example 2 had a recovery time of 122 min, with a small volume deviation, and still exhibited good recovery performance. Comparative Examples 2 and 3 could not completely recover their three-layer structure within 24 hours, and after shaking, they showed unclear interfaces and oil-water mixing.

[0080] Table 3 Results of Emulsion Droplet Size Detection

[0081]

[0082] As shown in Table 3, the droplet size of the emulsions in Examples 1-5 is significantly smaller than that in Comparative Examples 2 and 3, while the droplet size of the emulsions in Examples 3-5 is better than that in Examples 1 and 2. This indicates that the compound emulsifier can significantly reduce interfacial tension and improve emulsion stability, resulting in smaller and more uniform emulsion droplets.

[0083] Table 4. Results of moisturizing effect test (%)

[0084]

[0085] As shown in Table 4, the increase in skin moisture content after 4 hours in Examples 1-5 ranged from 13.7% to 29.3%, all exhibiting good moisturizing effects. The increase in moisture content after 4 hours in Comparative Examples 1-3 ranged from 0.7% to 8.7%, significantly lower than that in the Examples.

[0086] Table 5 Results of skin feel test (S1-S5 are Examples 1-5, D1-D3 are Comparative Examples 1-3)

[0087]

[0088] As shown in Table 5, the three-layer milk foam essence of the present invention performs well in terms of spreadability, absorption speed, refreshing feel, and moisturizing sensation. Among them, the overall effect of Examples 3-5 is significantly better than that of Examples 1-2, which should be attributed to the superior emulsifying effect of the compound emulsifier, which results in smaller emulsion particle size, more even spread during application, faster absorption, and a stronger refreshing sensation.

[0089] Of course, the present invention may have other various embodiments. Without departing from the spirit and essence of the present invention, those skilled in the art can make various corresponding changes and modifications according to the present invention, but these corresponding changes and modifications should all fall within the protection scope of the appended claims.

Claims

1. A three-layer milk foam essence, characterized in that: The essence has a three-layer structure in a stable state: an upper emulsion phase, a middle aqueous phase, and a lower oil phase. By weight, the essence comprises 55-90 parts water, 0.5-6.5 parts moisturizer, 0.3-2 parts emulsifier, 0.1-2.3 parts sodium chloride, 12-30 parts emollient A, 10-35 parts emollient B, 0.01-0.15 parts comfrey root extract, and 0.3-3 parts preservative. The moisturizer includes 1,3-propanediol, butylene glycol, 1,2-pentanediol, and glycerin. The emulsifier includes inulin lauryl carbamate. Emollient A includes neopentyl glycol di(ethylhexanoate), squalane, and caprylic / capric triglyceride. Emollient B includes trimethylpentaphenyltrisiloxane. The preservative includes phenoxyethanol, ethylhexylglycerin, and caprylyl glycol.

2. The three-layer milk foam essence according to claim 1, characterized in that: By weight, it includes 61-82 parts water, 1-5.5 parts moisturizer, 0.45-1.5 parts emulsifier, 0.2-2 parts sodium chloride, 15-27 parts emollient A, 20-30 parts emollient B, 0.02-0.1 parts colorant, and 1.5-3 parts preservative.

3. The three-layer milk foam essence according to claim 2, characterized in that: The mass ratio of the upper layer: middle layer: lower layer is (1-3):(4-7):(2-3).

4. The three-layer milk foam essence according to claim 2, characterized in that: The moisturizer comprises 0.1-1 parts of 1,3-propanediol, 0.2-2 parts of butylene glycol, 0.1-1 parts of 1,2-pentanediol, and 0.75-1.5 parts of glycerin.

5. The three-layer milk foam essence according to claim 2, characterized in that: The emulsifier also includes sucrose stearate, polyglycerol-6-distearate, and glycerol stearate citrate; the HLB of the glycerol stearate citrate is 13-16; by weight, inulin lauryl carbamate 0.25-0.5 parts, sucrose stearate 0.05-0.3 parts, polyglycerol-6-distearate 0.1-0.5 parts, and glycerol stearate citrate 0.05-0.2 parts.

6. The three-layer milk foam essence according to claim 2, characterized in that: The emollient A comprises 15-25 parts of neopentyl glycol di(ethylhexanoate), 0.1-1 parts of squalane, and 0.08-0.4 parts of caprylic / capric triglyceride; and / or; the emollient B comprises 20-30 parts of trimethylpentaphenyltrisiloxane.

7. The three-layer milk foam essence according to claim 2, characterized in that: The preservatives include 0.45-0.9 parts of phenoxyethanol, 0.35-0.7 parts of ethylhexylglycerin, and 0.7-1.4 parts of caprylyl glycol.

8. The method for preparing the three-layer milk foam essence according to any one of claims 1-6, characterized in that: Includes the following steps, Step a: Add water, humectant, emulsifier, and sodium chloride to the reaction vessel, heat and stir to obtain product A; Step b: Add emollient A, colorant, and preservative to the reaction vessel, heat and stir to obtain product B; Step c: Mix product A and product B, homogenize at 70-90℃ and 2500-5000 r / min for 15-35 min, then homogenize at 1500-2500 r / min until cooled to room temperature to obtain product C. Step d: Filter product C to obtain product D; Step e: Fill product D and moisturizer B in separate steps. First fill moisturizer B, then fill product D. The mass ratio of product D to moisturizer B is (7-8):(2-3). Let stand to obtain the finished product.

9. The method for preparing the three-layer milk foam essence according to claim 8, characterized in that: In step a, heat to 50-85℃ and stir at a speed of 15-50 r / min.

10. The method for preparing the three-layer milk foam essence according to claim 8, characterized in that: In step b, heat to 50-85℃ and stir at a speed of 15-50 r / min.

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