Pickering sunscreen lotion and preparation method thereof

Abstract

The present invention belongs to the field of cosmetics, and specifically discloses a Pickering sunscreen lotion and a preparation method thereof. The present invention uses particles in a composite sunscreen composition to replace surfactants as components for stabilizing the Pickering sunscreen lotion, thereby reducing the use of surfactants and making the sunscreen lotion have good sun protection and stability.

Description

Technical Field

[0001] The invention belongs to the field of cosmetics, and in particular relates to a Pickering sunscreen lotion and a preparation method thereof. Background Art

[0002] At present, people generally recognize that long-term exposure to ultraviolet rays will damage the epidermal cells of the skin, causing the skin to darken and become dry, burnt and inflamed, and even induce skin tumors and squamous cell carcinoma. Applying or spraying sunscreen products is currently a common means of sun protection or blocking ultraviolet absorption. The sun protection ability of sunscreen products is generally expressed by the sun protection factor (SPF). The higher the SPF value, the better the sun protection ability. Generally, sunscreen products with an SPF value of 20 can absorb 95% of ultraviolet radiation.

[0003] Currently, mainstream sunscreen products mainly use inorganic oxides such as titanium dioxide, zinc oxide, and organic UV absorbers to absorb and reflect a wide range of ultraviolet rays in the sun to achieve sun protection. Because they include inorganic and organic materials as well as other auxiliary functional components, the components are complex and the compatibility of the components is poor, resulting in poor stability.

[0004] Emulsification is the process of a liquid being dispersed evenly in another immiscible liquid in the form of extremely tiny droplets. Emulsification is a liquid-liquid interface phenomenon, where two immiscible liquids, such as oil and water, are separated into two layers in a container, with the oil of low density in the upper layer and the water of high density in the lower layer. Traditional emulsification requires the addition of appropriate surfactants, and then, under strong stirring, the oil is dispersed in the water to form an emulsion. In order to achieve better stability of sunscreen lotion products, a large amount of surfactants must be used. However, surfactants are highly irritating to the skin, which increases the cost of the product, and may also penetrate into the skin and stimulate epidermal cells, which may cause symptoms such as skin allergies. Different surfactants also bring about large differences in skin feel. At the same time, sunscreen products mainly increase the amount of sunscreen functional components to improve the sunscreen effect, but the degree of improvement is not large; the stability of sunscreen products also affects the dispersibility and application effect of the sunscreen functional components therein. Therefore, the sunscreen ability of conventional sunscreen products is still poor, and it is necessary to continue to develop a sunscreen product with excellent stability and sunscreen effect. Summary of the invention

[0005] In view of the problems of poor stability and sun protection ability of the sunscreen products involved in the above-mentioned prior art, the present invention will provide a Pickering sunscreen emulsion and a preparation method thereof.

[0006] To achieve the above purpose, the following technical solutions are specifically included:

[0007] A Pickering sunscreen lotion comprising the following components in percentage by weight:

[0008] Composite sunscreen composition 1-25%, acrylic acid (ester) / acrylamide copolymer 0.01-5%, organic ultraviolet absorber 1-20%, oily component 1-20%, stabilizer 0.1-10%, moisturizer 1-25%, chelating agent 0.1-1%, thickener 0.1-5%, preservative 0.1-1%, balance water,

[0009] The composite sunscreen composition comprises at least one of nano titanium dioxide, silica, chitosan, nano zinc oxide and starch.

[0010] The present invention uses particles in the composite sunscreen composition to replace surfactants as components for stabilizing the Pickering sunscreen lotion, thereby reducing the use of surfactants and making the sunscreen lotion have good sunscreen ability and stability.

[0011] Preferably, the Pickering sunscreen lotion comprises the following components in percentage by weight: 2-10% composite sunscreen composition, 0.5-2% acrylate / acrylamide copolymer, 2-10% organic UV absorber, 4-8% oily component, 0.5-2.5% stabilizer, 2-10% moisturizer, 0.1-1% chelating agent, 0.5-2% thickener, 0.1-1% preservative, and the remainder water.

[0012] Preferably, the composite sunscreen composition comprises nano titanium dioxide, silica and chitosan, and the mass ratio of the nano titanium dioxide, silica and chitosan is nano titanium dioxide: silica: chitosan = (2-5): (0.7-2): (0.3-2).

[0013] When the sunscreen lotion of the present invention contains nano titanium dioxide, silica and chitosan, the three components can synergistically improve the sunscreen effect; the acrylic acid (ester) / acrylamide copolymer can form a stable complex with chitosan, promote the dissolution of chitosan, and improve the compatibility and stability of the compounding of chitosan and other components; silica can thicken, adjust the viscosity of the system, improve the skin feel and smoothness, so that it can better cooperate with the nano titanium dioxide and chitosan to improve the stability of the system, and use diffuse reflection to reduce the absorption of ultraviolet rays to cooperate with other components for sunscreen. Therefore, the sunscreen lotion of the present invention has good sunscreen effect and stability, and the skin feels fresh and comfortable.

[0014] Acrylic acid (ester) / acrylamide copolymer is a water-soluble non-ionic polymer obtained by the binary copolymerization of non-ionic monomers acrylic acid ester and acrylamide. Its viscosity-average molecular weight can be 1.0×10 -5 In addition to improving the stability of nano-titanium dioxide, silica and chitosan in the system, acrylic acid (ester) / acrylamide copolymers can also act as film-forming agents in sunscreen lotions, making it easier to evenly apply the sunscreen lotion on the skin.

[0015] Chitosan contains a large amount of amino and hydroxyl groups, which are easily adsorbed on nano-titanium dioxide and silica, increasing the stability of the composite of nano-titanium dioxide and silica. In addition, due to the poor solubility of chitosan, adding acrylic acid (ester) / acrylamide copolymers to sunscreen can promote the dissolution of chitosan, further increase the effectiveness and stability of chitosan and its other components, and improve the sun protection effect. At the same time, chitosan itself is slightly darker in color, which can neutralize the "fake white" phenomenon of nano-titanium dioxide and silica, making the sunscreen closer to the skin color and more natural.

[0016] Preferably, the deacetylation degree of chitosan may be 45-98%.

[0017] Preferably, the mass percentage of the chitosan is 0-1%.

[0018] Further preferably, the mass ratio of nano-titanium dioxide, silica and chitosan is nano-titanium dioxide: silica: chitosan = (3-4.5): (1-2): (0.5-1).

[0019] Nano-titanium dioxide, silica and chitosan have better sun protection effects among the above qualities.

[0020] Preferably, the mass percentage of the composite sunscreen composition is 5-8%.

[0021] When the composite sunscreen composition is within the above content range, the sunscreen lotion has a better sunscreen effect.

[0022] Preferably, the nano titanium dioxide is hydrophobically modified titanium dioxide, and the hydrophobically modified titanium dioxide is titanium dioxide modified by a hydrophobic modifier, and the hydrophobic modifier includes at least one of (3-aminopropyl)trimethoxysilane, γ-aminopropyltriethoxysilane, γ-methacryloxypropyltrimethoxysilane, dimethylsiloxane, aluminum stearate, polyhydroxystearic acid, and aluminum oxide.

[0023] Preferably, the modified titanium dioxide is amino-modified titanium dioxide.

[0024] Preferably, the preparation method of the amino-modified titanium dioxide is: mixing nano-titanium dioxide, a hydrophobic modifier and a solvent, and performing a modification reaction at 80-150° C. to obtain modified titanium dioxide.

[0025] Preferably, the hydrophobic modifier includes at least one of (3-aminopropyl)trimethoxysilane, γ-aminopropyltriethoxysilane (KH-550), and γ-methacryloxypropyltrimethoxysilane.

[0026] Preferably, the solvent is at least one of ethanol and toluene.

[0027] Preferably, the modification reaction time is 2-12h;

[0028] Preferably, the mass percentage of the hydrophobic modifier to the nano-titanium dioxide is 5-15%.

[0029] Preferably, the mass ratio of the nano-titanium dioxide, the hydrophobic modifier and the solvent is nano-titanium dioxide: hydrophobic modifier: solvent = (5-15): (0.5-1.5):100.

[0030] Preferably, the average particle size of the composite sunscreen composition is 10-800 nm.

[0031] The inventors of the present invention have found that the stability and sun protection effect of hydrophobically modified titanium dioxide are improved, especially when amino-modified titanium dioxide is used, which may be because the titanium dioxide surface has more amino groups, which is conducive to complexing with acrylic acid (ester) / acrylamide copolymers, and can have a better compounding effect with silica and chitosan, thereby making the stability and sun protection effect of the sunscreen lotion better.

[0032] Preferably, the organic ultraviolet absorber includes at least one of ethylhexyl methoxycinnamate, bis-ethylhexyloxyphenol methoxyphenyl triazine, diethylaminohydroxybenzoyl hexyl benzoate, and octyl salicylate (ethylhexyl salicylate).

[0033] Organic ultraviolet absorbers can absorb ultraviolet rays and cooperate with the composite sunscreen composition to increase the sunscreen effect of the sunscreen lotion.

[0034] Preferably, the oily component includes at least one of C12-15 alcohol benzoate, diisopropyl adipate, diphenylsiloxyphenyl trimethicone, cyclopentasiloxane, cyclohexasiloxane, cyclic silicone oil, phenyl silicone oil, dimethicone, diethoxyethyl succinate, caprylic / capric triglyceride, isopropyl isostearate, ethylhexyl hydroxystearate, diethylhexyl succinate, isotridecyl isononanoate, and di(PPG-2 myristeth-10) adipate.

[0035] Oily ingredients mainly act as oil phase solvents and emollients, making sunscreen more stable and having appropriate emollient and moisturizing effects.

[0036] Preferably, the moisturizing agent includes at least one of 1,2-butylene glycol, 1,2-pentanediol, 1,2-hexanediol, 1,2-octanediol, 1,2-decanediol, 2-methyl-1,3-propanediol, and ethylhexylglycerin.

[0037] Preferably, the preservative includes at least one of p-hydroxyacetophenone, phenoxyethanol, phytic acid, sodium dehydroacetate, and benzyl alcohol.

[0038] Preferably, the stabilizer includes any one of polysorbate-20, polyacrylate-13, sorbitan isostearate, polyisobutylene, sorbitan sesquioleate, polysorbate-80, sodium acrylate / sodium acryloyldimethyl taurate copolymer, sorbitan oleate, PEG-7 trimethylolpropyl coconut ether, and hydroxyethyl acrylate / sodium acryloyldimethyl taurate copolymer.

[0039] Preferably, the chelating agent comprises disodium EDTA.

[0040] Preferably, the thickener includes at least one of carbomer, xanthan gum, cetearyl alcohol, sodium polyacrylate, acrylic acid (esters) / C10-30 alkyl acrylate crosspolymer, hydroxyethyl acrylate / sodium acryloyldimethyl taurate copolymer, acryloyldimethyl taurate amine / behenyl alcohol polyether-25 / methacrylate, and hydroxypropyl starch phosphate crosspolymer.

[0041] The present invention also provides a method for preparing the Pickering sunscreen lotion, comprising the following steps:

[0042] (1) mixing the composite sunscreen composition, acrylic acid (ester) / acrylamide copolymer, organic ultraviolet absorber, oily component, stabilizer and thickener at 70-90° C. to obtain an oil phase;

[0043] (2) mixing the moisturizer, chelating agent, preservative and water at 70-90° C. to obtain an aqueous phase;

[0044] (3) Adding the oil phase to the water phase and homogenizing under stirring to obtain the sunscreen lotion.

[0045] Preferably, the stirring rate is 500-3000 rpm.

[0046] Compared with the prior art, the present invention has the following beneficial effects:

[0047] (1) The Pickering sunscreen lotion of the present invention has good sunscreen effect and stability;

[0048] (2) In the Pickering sunscreen lotion of the present invention, the amount of sunscreen composition particles used is small, saving raw materials and reducing costs;

[0049] (3) The Pickering sunscreen lotion of the present invention has higher safety and can avoid the toxic side effects on the human body and the environment caused by the use of surfactants;

[0050] (4) The Pickering sunscreen emulsion of the present invention has good compatibility and is suitable for most oil phases and preservatives commonly used in cosmetics. The pH and salt concentration in the system can be varied within a wide range;

[0051] (5) The Pickering sunscreen lotion of the present invention has higher stability and can meet the requirement of long shelf life of cosmetics;

[0052] (6) In the Pickering sunscreen lotion of the present invention, in addition to the sunscreen composition particles themselves being able to impart specific efficacy to the Pickering lotion, the lotion can also simultaneously embed other bioactive ingredients to construct multi-functional cosmetics;

[0053] (7) In the Pickering sunscreen lotion of the present invention, the unique oil-water interface structure formed by the sunscreen composition particles can achieve better protection and controllable release of bioactive substances, and may also achieve selective percutaneous absorption;

[0054] (8) The unique and controllable rheological properties of the Pickering sunscreen lotion of the present invention can provide the texture and viscosity required by the product, thereby giving the lotion a better sensory experience. DETAILED DESCRIPTION

[0055] In order to better illustrate the purpose, technical scheme and advantages of the present invention, the present invention will be further described below through specific examples. The test methods used in the examples and / or comparative examples are conventional methods unless otherwise specified; the materials, reagents, etc. used can be obtained from commercial channels unless otherwise specified.

[0056] The deacetylation degree of the chitosan used below is 85%; the raw materials used in the present invention are all commercially available.

[0057] Examples 1-15 and Comparative Examples 1-3

[0058] The preparation method of the sunscreen lotion of Examples 1-15 and Comparative Examples 1-3 comprises the following steps:

[0059] (1) According to the formula in Tables 1 and 2, the composite sunscreen composition, the oily component, the acrylic acid (ester) / acrylamide copolymer, the organic ultraviolet absorber, the stabilizer, and the thickener are mixed uniformly at 85° C. to obtain an oil phase;

[0060] (2) mixing a moisturizer, a chelating agent, a preservative and water at 85° C. according to the formula in Tables 1 and 2 to obtain a water phase;

[0061] (3) adding the oil phase to the water phase and homogenizing the mixture under stirring at 1500 rpm to obtain the sunscreen lotion;

[0062] The composite sunscreen composition is nano titanium dioxide or modified titanium dioxide, silica, chitosan, and nano zinc oxide; the organic ultraviolet absorber, oily component, stabilizer, and thickener are octyl salicylate (ethylhexyl salicylate), cyclopentasiloxane, sorbitan sesquioleate, and cetearyl alcohol; the moisturizer, chelating agent, and preservative are 1,2-butylene glycol, disodium EDTA, and p-hydroxyacetophenone;

[0063] In Comparative Example 3, vinyl pyrrolidone / vinyl acetate copolymer was used to replace acrylic acid (ester) / acrylamide copolymer;

[0064] Wherein, the preparation method of modified titanium dioxide 1-5 is as follows:

[0065] Nano-titanium dioxide, a hydrophobic modifier and ethanol are mixed, and a modification reaction is carried out at 120° C. for 6 h (in a reflux device) under stirring to obtain modified titanium dioxide, wherein the hydrophobic modifiers used in the modified titanium dioxides 1-3 are (3-aminopropyl)trimethoxysilane, γ-aminopropyltriethoxysilane and γ-methacryloxypropyltrimethoxysilane, respectively, and the mass ratio of nano-titanium dioxide, the hydrophobic modifier and the ethanol is 10:1:100;

[0066] The preparation process of modified titanium dioxide 4 and 5 differs from that of modified titanium dioxide 1 only in the amount of (3-aminopropyl)trimethoxysilane used, specifically: in modified titanium dioxide 4, the mass ratio of nano titanium dioxide, hydrophobic modifier and ethanol is 10:0.5:100; in modified titanium dioxide 5, the mass ratio of nano titanium dioxide, hydrophobic modifier and ethanol is 10:1.5:100.

[0067] Table 1

[0068]

[0069] Table 2

[0070]

[0071] Performance Test:

[0072] (1) Stability

[0073] After the sunscreen lotions of the above-mentioned embodiments and comparative examples were prepared, they were placed at room temperature for 1 hour, and no separation was observed. After further storage at 40° C. for 30 days, the lotions were observed again, and the stability level was evaluated according to the following criteria:

[0074] A: No separation was confirmed;

[0075] B: Very slightly separated;

[0076] C: Significant separation;

[0077] D: separated 1 hour after preparation;

[0078] In the present invention, grade B and above are judged as having excellent stability, i.e., meeting the requirements. The test results are shown in Table 3.

[0079] (2) SPF value: The test method is based on ISO 24443-2021. First, measure the blank film of the carrier as the background curve, then use a 1mL syringe to draw the sample and evenly apply it on the Transpore MTR type transparent tape. Use a finger wearing a latex finger cot to quickly and evenly apply it on the film so that the sample on the film surface is 2 mg / cm 2 Distribution; then place the coated sample plate in an environment with a temperature of 25°C and a humidity of 60% to dry naturally for 15 minutes, use a sun protection factor analyzer SPF-290AS to select 9 points on the sample on the transparent tape for testing, and calculate the SPF average value. The test results are shown in Table 3.

[0080] Table 3

[0081]

[0082] It can be seen from Examples 1-15 that the sunscreen lotion of the present invention has excellent stability, good sunscreen performance, and an SPF of 11-31.9.

[0083] It can be seen from Examples 1, 12-14 and Comparative Example 1 that in the sunscreen lotion of the present invention, nano titanium dioxide, silica and chitosan have the characteristic of synergistically improving the sunscreen effect.

[0084] It can be seen from Example 1 and Comparative Examples 2-3 that, compared with other conventional film-forming agents, in the sunscreen lotion of the present invention, the acrylic acid (ester) / polydimethylsiloxane copolymer can significantly improve the stability and dispersibility of the system, thereby helping to improve the sunscreen effect of the sunscreen lotion.

[0085] It can be seen from Examples 7-11 that hydrophobic modification of titanium dioxide can significantly improve the dispersion effect of titanium dioxide in sunscreen lotion, thereby better cooperating with other components to improve the sunscreen performance of the sunscreen lotion. In particular, when nano titanium dioxide is modified with an amino-containing hydrophobic modifier, its sunscreen effect is better. However, the degree of hydrophobicity of the modification needs to be moderate, otherwise, its hydrophobic effect is excessive, which will affect the coordination effect of the modified titanium dioxide with the other components and reduce the stability of the system.

[0086] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the essence and scope of the technical solution of the present invention.

Claims

1. A Pickering sunscreen lotion, characterized in that The invention comprises the following components in percentage by weight: 2-10% of composite sunscreen composition, 0.5-2% of acrylic acid (ester) / acrylamide copolymer, 2-10% of organic ultraviolet absorber, 4-8% of oily component, 0.5-2.5% of stabilizer, 2-10% of moisturizer, 0.1-1% of chelating agent, 0.5-2% of thickener, 0.1-1% of preservative, and the balance of water. The composite sunscreen composition comprises nano titanium dioxide, silica and chitosan, wherein the mass ratio of the nano titanium dioxide, silica and chitosan is nano titanium dioxide: silica: chitosan = (2-5): (0.7-2): (0.3-2); the stabilizer is sorbitan sesquioleate.

2. The Pickering sunscreen lotion according to claim 1, characterized in that The nano titanium dioxide is hydrophobically modified titanium dioxide; the hydrophobically modified titanium dioxide is titanium dioxide modified by a hydrophobic modifier, and the hydrophobic modifier includes at least one of (3-aminopropyl)trimethoxysilane, γ-aminopropyltriethoxysilane, γ-methacryloxypropyltrimethoxysilane, dimethylsiloxane, aluminum stearate, polyhydroxystearic acid, and aluminum oxide.

3. The Pickering sunscreen lotion according to claim 2, characterized in that The preparation method of the hydrophobically modified titanium dioxide comprises: mixing nano titanium dioxide, a hydrophobic modifier and a solvent, and performing a modification reaction at 80-150° C. to obtain the modified titanium dioxide.

4. The Pickering sunscreen lotion according to claim 3, characterized in that The hydrophobic modifier accounts for 5-15% of the mass of the nano-titanium dioxide.

5. The Pickering sunscreen lotion according to claim 1, characterized in that The organic ultraviolet absorber includes at least one of ethylhexyl methoxycinnamate, bis-ethylhexyloxyphenol methoxyphenyl triazine, diethylaminohydroxybenzoyl hexyl benzoate, and octyl salicylate (ethylhexyl salicylate).

6. The Pickering sunscreen lotion according to claim 1, characterized in that Include at least one of the following: The oily component includes at least one of C12-15 alcohol benzoate, diisopropyl adipate, diphenylsiloxyphenyl trimethicone, cyclopentasiloxane, cyclohexasiloxane, cyclic silicone oil, phenyl silicone oil, dimethicone, diethoxyethyl succinate, caprylic / capric triglyceride, isopropyl isostearate, ethylhexyl hydroxystearate, diethylhexyl succinate, isotridecyl isononanoate, and di(PPG-2 myreth-10) adipate; The moisturizing agent includes at least one of 1,2-butylene glycol, 1,2-pentanediol, 1,2-hexanediol, 1,2-octanediol, 1,2-decanediol, 2-methyl-1,3-propanediol, and ethylhexylglycerol; The average particle size of the composite sunscreen composition is 10-800 nm.

7. The Pickering sunscreen lotion according to claim 1, characterized in that Include at least one of the following: The preservative includes at least one of p-hydroxyacetophenone, phenoxyethanol, phytic acid, sodium dehydroacetate, and benzyl alcohol; The chelating agent includes disodium EDTA; The thickener includes at least one of carbomer, xanthan gum, cetearyl alcohol, sodium polyacrylate, acrylic acid (ester) / C10-30 alkyl acrylate cross-linked polymer, hydroxyethyl acrylate / sodium acryloyldimethyl taurate copolymer, acryloyldimethyl taurate amine / behenyl alcohol polyether-25 / methacrylate, and hydroxypropyl starch phosphate cross-linked polymer.

8. A method for preparing the Pickering sunscreen lotion according to any one of claims 1 to 7, characterized in that: The steps include: (1) mixing the composite sunscreen composition, acrylic acid (ester) / acrylamide copolymer, organic ultraviolet absorber, oily component, stabilizer and thickener at 70-90° C. to obtain an oil phase; (2) mixing the moisturizer, chelating agent, preservative and water at 70-90° C. to obtain an aqueous phase; (3) Adding the oil phase to the water phase and homogenizing under stirring to obtain the sunscreen lotion.

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