Emulsifier-free stable sunscreen emulsion capable of forming film through phase inversion and preparation method thereof

Abstract

The invention relates to the technical field of sunscreen emulsions, in particular to an emulsifier-free stable sunscreen emulsion capable of phase inversion and film formation and a preparation method thereof.The emulsifier-free stable sunscreen emulsion comprises an oil phase and a water phase, and the oil phase at least comprises, by mass, 0.1-5% of silicone oil, 1-25% of nano-powder dispersion slurry, 0.1-5% of an emollient and 10-40% of an oil-soluble sunscreen agent; the water phase at least comprises 0.5-9% of silica, 0.03-0.4% of sodium hyaluronate and the balance of deionized water, the average particle size D50 of the silica is smaller than or equal to 7 micrometers, under the condition that no extra emulsifier or film-forming agent is added, the product can be smeared for phase inversion and automatically form a film, the waterproof, sweat-resistant, refreshing and non-greasy effects are guaranteed, and the product has extremely high market application and popularization value.

Description

Technical Field

[0001] The invention relates to the technical field of sunscreen lotions, in particular to a stable sunscreen lotion which does not contain an emulsifier and can be phase-transformed into a film and a preparation method thereof. Background Art

[0002] Commercially available sunscreen lotions usually include emulsifiers and are divided into water-in-oil formula systems and oil-in-water formula systems. Based on the specific use requirements of sunscreen lotions, water-in-oil sunscreen lotions cannot protect against sunburn and sweat due to the insufficient retention of the formula. The sunscreen performance in human efficacy tests is insufficient, which limits its production and sales. The prior art adds additional polymer film-forming agents to the water-in-oil formula system to increase its retention capacity. For example, a Chinese patent (authorization announcement number CN109833214B) discloses a mild water-in-oil pickering sunscreen skin care product, which improves the waterproof and sweat-resistant effect by adding sodium polyacryloyldimethyl taurate, but it still cannot meet the actual use requirements. Therefore, the oil-in-water formula has gradually become the mainstream system of sunscreen lotions on the market.

[0003] In oil-in-water sunscreen lotions, oil is the external phase, forming a natural waterproof barrier. The product is not easy to remove when used, which effectively ensures the continuous output of the product's sun protection ability. However, the emulsifier used in the oil-in-water formula is a type of stable oil-in-water polymerized multifunctional emulsifier due to the molecular chain polymerization of polydimethylsiloxane functional groups. Its molecular weight is often large, and the general molecular weight is above 5000-10000 Daltons. The addition of high molecular weight emulsifiers increases the stickiness of the formula, reduces the freshness, and causes discomfort when used. At the same time, the external phase (oil phase) of the oil-in-water sunscreen lotion is generally 30-40% and the internal phase (water phase) is 60-70% by mass percentage. In order to stabilize the internal phase and make the emulsion droplets tight and stable, a high-strength emulsified interface film needs to be formed, which also makes the interfacial tension of the emulsion very large, which in turn leads to a large application resistance of the emulsion when used, making the greasy skin feel even more sticky and uncomfortable. In addition, when the water-in-oil sunscreen lotion formula containing surfactants comes into contact with water and sweat, the oil film will undergo molecular migration, and the oil film is not strong enough to ensure that it will not come off for a long time. For example, a Chinese patent (authorization announcement number CN111150677B) discloses a sunscreen cosmetic and its preparation method, which improves the skin feel of the product by introducing polyquaternium-37, but cannot guarantee the long-lasting effect. Adding hydrophobic film-forming ingredients will bring higher molecular weight and more sticky and obstructive skin feel. Some products sacrifice stability at the cost of adding 0.5-1% emulsifier to achieve the purpose of improving skin feel, but they need to be shaken well when used, and the packaging is limited, the manufacturing cost is high, and the operability is insufficient, which limits its application. Summary of the invention

[0004] In order to solve the above problems, the present invention provides a stable sunscreen lotion that does not contain an emulsifier and can form a phase transition film. Without adding any additional emulsifier or film-forming agent, the product can be applied, transition phase and form a film independently to ensure waterproof, sweat-resistant, refreshing and non-greasy effects, and has extremely high market application and promotion value.

[0005] On one hand, the present invention provides a stable sunscreen lotion that does not contain an emulsifier and can be phase-transformed into a film, comprising an oil phase and an aqueous phase. In terms of mass percentage, the oil phase comprises at least: 0.1-5% silicone oil, 1-25% nanopowder dispersion slurry, 0.1-5% emollient, and 10-40% oil-soluble sunscreen agent; the aqueous phase comprises at least: 0.5-9% silica, 0.03-0.4% sodium hyaluronate, and the balance is made up of deionized water.

[0006] As a preferred technical solution, the addition amount of the nano powder dispersion slurry is 2-10% based on the mass of the sunscreen lotion.

[0007] As a preferred technical solution, the nano-powder dispersion slurry at least includes nano-powder and a dispersion carrier, and the nano-powder is selected from at least one of nano-titanium dioxide, nano-zirconia, and nano-zinc oxide, preferably nano-titanium dioxide.

[0008] Preferably, the mass proportion of the nanopowder is 20-50%, preferably 40%.

[0009] Preferably, the nano powder dispersion slurry is a 40wt% nano TiO2 dispersion slurry (TINOPLY E50C) As a preferred technical solution, the emollient at least includes isononyl isononanoate.

[0010] As a preferred technical solution, the silicone oil at least includes cyclopentasiloxane and polydimethylsiloxane.

[0011] Preferably, the polydimethylsiloxane is selected from at least one polydimethylsiloxane having a viscosity of 1-350 cSt at 25°C.

[0012] As an example, the polydimethylsiloxane is selected from at least one of polydimethylsiloxanes having a viscosity of 1 cSt, 1.5 cSt, 2 cSt, 2.5 cSt, 3 cSt, 10 cSt, 20 cSt, 50 cSt, 100 cSt, 150 cSt, 200 cSt, 250 cSt, 300 cSt, and 350 cSt at 25°C.

[0013] Preferably, the polydimethylsiloxane is a combination of polydimethylsiloxane siloxane A having a viscosity of 1-2 cSt at 25°C and polydimethylsiloxane B having a viscosity of 300-350 cSt.

[0014] As a preferred technical solution, the mass ratio of cyclopentasiloxane, polydimethylsiloxane A and polydimethylsiloxane B is (1-2): (0.5-2): (0.5-1.5), preferably (1-2): 1: (0.5-1). As a preferred technical solution, the oil-soluble sunscreen is selected from at least one of ethylhexyl methoxycinnamate, octocrylene, ethylhexyl salicylate, bis-ethylhexyloxyphenol methoxyphenyl triazine, diethylaminohydroxybenzoyl hexyl benzoate, ethylhexyl triazone, and polysilicone-15.

[0015] Preferably, based on the mass of the sunscreen lotion, the oil-soluble sunscreen agent includes: 5-10% ethylhexyl methoxycinnamate, 2-6% octocrylene, 2-6% ethylhexyl salicylate, 2-65% bis-ethylhexyloxyphenol methoxyphenyl triazine, 1-3% diethylaminohydroxybenzoyl hexyl benzoate, 0.1-1% ethylhexyl triazone, and 2-5% polysilicone-15.

[0016] As a preferred technical solution, based on the mass of the sunscreen lotion, the oil phase further includes 0.1-2% isododecane and 0.01-0.3% tocopherol (vitamin E).

[0017] As a preferred technical solution, the added amount of the silica is 1.5-4.5% based on the mass of the sunscreen lotion.

[0018] As examples, the silica is added in an amount of 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, or 4.5%.

[0019] Preferably, the average particle size D50 of the silica is ≤7 μm, preferably 1-7 μm, most preferably 5±2 μm, the model is Kingsica5020, Liankai powder.

[0020] As a preferred technical solution, the added amount of sodium hyaluronate is 0.05-0.3% based on the mass of the sunscreen lotion.

[0021] As an example, the added amount of sodium hyaluronate is 0.05%, 0.08%, 0.1%, 0.12%, 0.15%, 0.2%, 0.25%, and 0.3%.

[0022] As a preferred technical solution, the molecular weight of the sodium hyaluronate is 1.0-1.8 MDa, preferably 1.0-1.5 MDa.

[0023] Preferably, the sodium hyaluronate is moistuHA® sodium hyaluronate.

[0024] As a preferred technical solution, the water phase also includes a preservative, a pH adjuster, a conditioner, and a moisturizer.

[0025] As a preferred technical solution, based on the mass of the sunscreen lotion, the aqueous phase includes: 1.5-4.5% silica, 0.05-0.3% sodium hyaluronate, 0.01-0.4% p-hydroxyacetophenone, 0.1-0.5% 1,2-hexanediol, 0.01-0.2% niacinamide, 0.001-0.03% citric acid, 0.01-0.2% sodium citrate, 0.1-5% 1,3-butylene glycol, 0.1-8% glycerol, 0.01-0.5% allantoin, and deionized water makes up the balance.

[0026] The present invention simultaneously adds nano powder dispersion, silica and sodium hyaluronate, so that the sunscreen lotion provided is in a water-in-oil state when it does not contact the skin. When lightly applied on the skin surface, the emulsion automatically changes phases to an oil-in-water state, which not only ensures a refreshing and non-greasy use experience, but also has a relatively stable oil-in-water state, and the surface forms a film autonomously to ensure a long-lasting makeup effect. The reason for this may be that the nano colloidal particles in the sunscreen lotion form a stable adsorption angle with the water phase and the oil phase. When the adsorption angle is less than 90°, the emulsion is in a water-in-oil state, and when the adsorption angle is greater than 90°, the emulsion is in an oil-in-water state. Therefore, the change between the two states before and after application can be achieved, thereby simultaneously ensuring the skin feel of the emulsion and the long-lasting makeup effect.

[0027] However, the stability of the emulsion cannot be guaranteed in the early stage of product development. The emulsion obtained by directly introducing nanopowders shows oil-water separation. Based on a large number of exploratory experiments, it is found that the selection, combination and addition amount control of nanopowder dispersion slurry, silica and sodium hyaluronate directly affect the stability of the emulsion. The present invention adopts nano-titanium dioxide dispersion slurry, silica with an average particle size D50≤7μm and moistuHA® sodium hyaluronate, and controls the addition amount of silica to 0.5-9%, so that the prepared sunscreen lotion has qualified color, appearance, viscosity range, centrifugal, cold and heat stability, thereby ensuring the subsequent use effect and sunscreen effect.

[0028] Furthermore, the sunscreen lotion provided by the present invention ensures the sunscreen effect of the sunscreen lotion by preferably selecting the oil-soluble sunscreen agent as a combination of ethylhexyl methoxycinnamate, octocrylene, ethylhexyl salicylate, bis-ethylhexyloxyphenol methoxyphenyl triazine, diethylamino hydroxybenzoyl hexyl benzoate, ethylhexyl triazone, and polysilicone-15.

[0029] The sunscreen lotion provided by the present invention achieves the water and sweat resistance and effect that only other water-in-oil formulas with added film-forming agents on the market have, without adding additional film-forming agents, and achieves a new breakthrough in the technical field of sunscreen lotion formulas.

[0030] On the other hand, the present invention provides a method for preparing a stable sunscreen emulsion that does not contain an emulsifier and can be phase-transformed into a film, which comprises at least the following steps: adding an oil phase raw material into an oil phase pot, heating it to 85°C-90°C, and stirring it until it is dissolved to obtain an oil phase; adding an aqueous phase raw material into an emulsifying pot, heating it to 80°C-85°C, and homogenizing and stirring it to obtain an aqueous phase; adding the aqueous phase into the oil phase, with a homogenizing speed of 2000-4000rpm, homogenizing and emulsifying for 3-8min, and keeping the temperature at 80-82°C; after emulsification, vacuum defoaming, cooling and venting the vacuum, continuing cooling, sampling and testing to obtain the product after passing the test.

[0031] The sunscreen lotion provided by the invention has readily available raw materials, a simple preparation method, is easy to control, and is easy to realize large-scale industrial production.

[0032] Beneficial Effects 1. The present invention provides a stable sunscreen lotion that does not contain an emulsifier and can form a phase transition film. Without adding any additional emulsifier or film-forming agent, the product can be applied, phase transitioned, and independently formed into a film to ensure waterproof, sweat-resistant, refreshing, and non-greasy effects, and has a very high market application and promotion value.

[0033] 2. The present invention simultaneously adds nano powder dispersion, silica and sodium hyaluronate, so that the sunscreen lotion provided is in a water-in-oil state when it does not contact the skin. When it is gently applied on the skin surface, the emulsion automatically changes phase to an oil-in-water state, which not only ensures a refreshing and non-greasy use experience, but also has a relatively stable oil-in-water state, and the surface forms a film autonomously to ensure a long-lasting makeup effect.

[0034] 3. The present invention simultaneously adds nano powder dispersion, silica and sodium hyaluronate, so that the sunscreen lotion provided is in a water-in-oil state when it does not contact the skin. When it is gently applied on the skin surface, the emulsion automatically changes phase to an oil-in-water state, which not only ensures a refreshing and non-greasy use experience, but also has a relatively stable oil-in-water state, and the surface forms a film autonomously to ensure a long-lasting makeup effect.

[0035] 4. The sunscreen lotion provided by the present invention ensures the sunscreen effect by selecting the combination of ethylhexyl methoxycinnamate, octocrylene, ethylhexyl salicylate, bis-ethylhexyloxyphenol methoxyphenyl triazine, diethylamino hydroxybenzoyl hexyl benzoate, ethylhexyl triazone and polysilicone-15 as the oil-soluble sunscreen agent.

[0036] 5. The sunscreen lotion provided by the present invention achieves the water and sweat resistance and effect that only other oil-in-water formulas on the market that add film-forming agents have, without adding additional film-forming agents, achieving a new breakthrough in the field of sunscreen lotion formula technology. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1This is a product appearance diagram provided for Example 1 of the present invention.

[0038] Figure 2 This is a product appearance diagram provided for Comparative Example 1 of the present invention.

[0039] Figure 3 This is a diagram showing the waterproof effect of the product provided in Example 1 of the present invention.

[0040] Figure 4 This is a diagram showing the waterproof effect of the product provided in Example 2 of the present invention.

[0041] Figure 5 This is a film-forming effect diagram of the product provided in Example 3 of the present invention. DETAILED DESCRIPTION

[0042] The grades of the raw materials in the examples and comparative examples of the present invention are shown in Table 1.

[0043] Table 1

[0044] Examples 1-3 Examples 1-3 of the present invention provide a stable sunscreen emulsion that does not contain an emulsifier and can form a phase transition film. The raw materials for its preparation are shown in Table 2 in terms of mass percentage.

[0045] Table 2

[0046] On the other hand, embodiments 1-3 of the present invention provide a method for preparing a stable sunscreen lotion that does not contain an emulsifier and can be phase-transformed into a film, comprising the following steps: adding an oil phase raw material to an oil phase pot, heating it to 87°C, and stirring until dissolved to obtain an oil phase; adding an aqueous phase raw material to an emulsifying pot, heating it to 84°C, and homogenizing and stirring to obtain an aqueous phase; adding the aqueous phase to the oil phase, with a homogenizing speed of 2800rpm, homogenizing and emulsifying for 5 minutes, and keeping the temperature at 82°C; after emulsification is completed, vacuum (-0.2Pa) defoaming, cooling to 42°C and venting the vacuum, continuing to cool to 38°C, sampling and inspecting the product, and discharging the product.

[0047] Comparative Examples 1-6 Comparative Examples 1-6 of the present invention provide a sunscreen lotion, and the raw materials for its preparation are shown in Table 3 in terms of mass percentage.

[0048] Table 3

[0049] On the other hand, Comparative Examples 1-6 of the present invention provide a method for preparing a sunscreen lotion, comprising the following steps: adding the oil phase raw material to an oil phase pot, heating it to 87°C, and stirring until dissolved to obtain the oil phase; adding the water phase raw material to an emulsifying pot, heating it to 84°C, and homogenizing and stirring to obtain the water phase; adding the water phase to the oil phase, with a homogenizing speed of 2800rpm, homogenizing and emulsifying for 5 minutes, and keeping warm at 82°C; after emulsification is completed, defoaming under vacuum (-0.2Pa), cooling to 42°C and excluding vacuum, continuing to cool to 38°C, and discharging after sampling and inspection.

[0050] Performance Testing 1. The sun protection value of the sunscreen lotions provided in Examples 1-3 and Comparative Examples 1-6 was calculated using the BASF sun protection value calculator. The test results are shown in Table 4.

[0051] Table 4

[0052] 2. Physical and chemical tests were performed on the sunscreen lotions provided in Examples 1-3 and Comparative Examples 1-6. The test reference standards, test items, and test results are shown in Tables 5-13, respectively. The product appearance is shown in Table Figure 1 , 2 .

[0053] Table 5 Physical and chemical test results of Example 1

[0054] Table 6 Physical and chemical test results of Example 2

[0055] Table 7 Physical and chemical test results of Example 3

[0056] Table 8 Physical and chemical test results of comparative example 1

[0057] Table 9 Comparative Example 2 Physical and Chemical Test Results

[0058] Table 10 Comparative Example 3 Physical and Chemical Test Results

[0059] Table 11 Comparative Example 4 Physical and Chemical Test Results

[0060] Table 12 Physical and chemical test results of comparative example 5

[0061] Table 13 Physical and chemical test results of comparative example 6

[0062] Analysis of the above table shows that the sunscreen lotions provided by Examples 1-3 have satisfactory product stability relative to Comparative Examples 1-6, thereby ensuring the subsequent sunscreen effect. The sunscreen lotion provided by the present invention requires the addition of nanopowder dispersion, silica and sodium hyaluronate at the same time and the addition amount thereof is controlled to ensure product stability.

[0063] 3. Waterproof effect: The waterproof effect of the products provided in Example 1 and Example 2 was tested (the same amount of Example 1 and Example 2 were applied, and then rinsed with running water for 10 minutes after 2 minutes to check the residual condition of the material body and determine the waterproof effect). The test results are shown in Figure 3 , Figure 4 ,observe Figure 3 , 4 It can be seen that there is no obvious change before and after flushing, indicating that the products provided by Example 1 and Example 2 have good waterproof effect.

[0064] 4. Film-forming effect: The film-forming effect of the product provided in Example 3 was tested. The product provided in Example 3 was applied to the skin surface at an application amount of 1 g / 4 cm 2 After 2 minutes, use a small ball to test the film-forming effect. The test results are shown in Figure 5 ,observe Figure 5 It can be seen that the small balls adhere to the skin surface, indicating that a film is formed on the skin surface in 2 minutes.

Claims

1. A stable sunscreen emulsion that does not contain an emulsifier and can form a phase transition film, characterized in that: It includes an oil phase and an aqueous phase. In terms of mass percentage, the oil phase at least includes: 0.1-5% silicone oil, 1-25% nano powder dispersion slurry, 0.1-5% emollient, and 10-40% oil-soluble sunscreen; the aqueous phase at least includes: 0.5-9% silica, 0.03-0.4% sodium hyaluronate, and deionized water to make up the balance, and the average particle size D50 of the silica is ≤7μm.

2. The stable sunscreen emulsion without emulsifier and capable of phase inversion and film formation according to claim 1, characterized in that: The amount of the nano powder dispersion slurry added is 2-10% based on the mass of the sunscreen lotion.

3. The stable sunscreen emulsion without emulsifier and capable of phase inversion and film formation according to claim 2, characterized in that: The nano powder dispersion slurry at least includes nano powder and a dispersion carrier, and the nano powder is selected from at least one of nano titanium dioxide, nano zirconium oxide, and nano zinc oxide.

4. The stable sunscreen emulsion capable of phase inversion and film formation without emulsifier according to claim 1, characterized in that: The emollient includes at least isononyl isononanoate.

5. The stable sunscreen emulsion capable of phase inversion and film formation without emulsifier according to claim 1, characterized in that: The silicone oil at least includes cyclopentasiloxane and polydimethylsiloxane.

6. The stable sunscreen emulsion capable of phase inversion and film formation without emulsifier according to claim 1, characterized in that: The oil-soluble sunscreen is selected from at least one of ethylhexyl methoxycinnamate, octocrylene, ethylhexyl salicylate, bis-ethylhexyloxyphenol methoxyphenyl triazine, diethylaminohydroxybenzoyl hexyl benzoate, ethylhexyl triazone, and polysilicone-15.

7. The stable sunscreen emulsion capable of phase inversion and film formation without emulsifier according to claim 1, characterized in that: Based on the mass of the sunscreen lotion, the oil phase further comprises 0.1-2% isododecane and 0.01-0.3% tocopherol.

8. The stable sunscreen emulsion capable of phase inversion and film formation without emulsifier according to claim 1, characterized in that: The added amount of the silica is 1.5-4.5% based on the mass of the sunscreen lotion.

9. The stable sunscreen emulsion capable of phase inversion and film formation without emulsifier according to claim 1, characterized in that: Based on the mass of the sunscreen lotion, the added amount of the sodium hyaluronate is 0.05-0.3%.

10. A method for preparing a stable sunscreen emulsion that does not contain an emulsifier and can form a phase-inverting film according to any one of claims 1 to 9, characterized in that: The method comprises at least the following steps: adding the oil phase raw material into the oil phase pot, heating it to 85°C-90°C, stirring it until it is dissolved to obtain the oil phase; adding the water phase raw material into the emulsifying pot, heating it to 80°C-85°C, stirring it homogenously to obtain the water phase; adding the water phase into the oil phase, with the homogenizing speed of 2000-4000rpm, homogenizing and emulsifying for 3-8min, and keeping the temperature at 80-82°C; after the emulsification is completed, vacuum defoaming, cooling and venting the vacuum, continuing cooling, sampling and testing to obtain the material after it is qualified.

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