Sunscreen serum gel containing active microcapsules and method for preparing same

Abstract

The present application relates to the functional skin care product technical field, disclose a kind of active material microcapsule-containing sunscreen essence gel and its preparation method.The sunscreen essence gel is composed of sunscreen gel and active material microcapsule;The sunscreen gel is prepared from oil phase and water phase, and the oil phase contains dimethicone, cresol trisiloxane, trimethylsiloxy silicate, isopentyl p-methoxycinnamate and REG 1103 B, and the water phase contains p-xylylene bis-camphor sulfonic acid, phenyl benzimidazole sulfonic acid, phenyl benzimidazole tetrasulfate disodium, tromethamine, aminomethyl propanol, glycerol and water;The active material microcapsule is a core-shell microcapsule embedding silymarin.The product can be used for sunscreen skin care.

Description

Technical Field

[0001] This application belongs to the field of functional skincare technology, specifically relating to a sunscreen essence gel containing active ingredient microcapsules and its preparation method. Background Technology

[0002] Sunscreen cosmetics typically achieve UVA / UVB protection by adding chemical sunscreens (organic sunscreens), inorganic sunscreens, or a combination of both. Traditional sunscreen lotions or creams often contain large amounts of oils or physical sunscreens (such as zinc oxide and titanium dioxide), resulting in a heavy, sticky, or white-tinged experience. As consumers increasingly demand a "refreshing feel, transparent appearance, and long-lasting film," transparent sunscreen gels / gels are becoming more common, representing a significant market innovation trend due to their visual purity and cooling, watery texture. However, sunscreen gels usually use a single water-soluble sunscreen agent, and achieving high SPF protection while addressing issues like solubility and stickiness remains. Therefore, achieving a transparent appearance, high SPF protection, and stability still presents several technical challenges for sunscreen gels.

[0003] To achieve a safer and more pleasant experience, the industry is gradually exploring the use of bio-sunscreens (or active skincare ingredients) to partially replace or supplement traditional chemical sunscreens. These ingredients are typically derived from natural extracts or active substances with antioxidant and anti-inflammatory properties (such as certain polyphenols, flavonoids, vitamins, and their derivatives). They not only provide indirect sun protection by neutralizing free radicals but also improve skin health mechanistically, while avoiding the potential irritation or environmental controversies associated with some chemical sunscreens. However, applying bio-sunscreens to transparent sunscreen gels faces a core technical bottleneck: stability. Many active ingredients with bio-sunscreen potential (such as resveratrol, ferulic acid, and some polyphenols and vitamin C derivatives) are easily decomposed and oxidized by light. In transparent formulations, these active substances are directly exposed to light and oxygen, rapidly degrading and deactivating, leading to product discoloration, reduced efficacy, and failure to deliver long-lasting, stable protection. Therefore, effectively protecting these fragile active substances without affecting the product's transparent appearance has become a key challenge in developing the next generation of high-end transparent sunscreen products.

[0004] Against this backdrop, microencapsulation technology is considered an ideal solution. By encapsulating active ingredients in tiny capsule walls (such as agar microcapsules), they can be physically isolated from adverse external environments, thereby significantly improving stability and potentially enabling controlled release. Chinese invention patent CN104434548A, published on March 25, 2015, discloses a hydrogel microcapsule with sun protection efficacy. The sun protection ingredients include cardamom extract, astaxanthin, or honeysuckle extract. By encapsulating the active ingredients, the sun protection activity of the cardamom extract can be effectively protected. Existing technologies only address the protection of active ingredients by microcapsules, but do not solve the stability issues (sedimentation, capsule rupture, depermeability, and stratification) of microcapsules in transparent sunscreen gels. Traditional sunscreen gel formulation matrices (especially those containing PEG emulsions) have poor compatibility with hydrogel microcapsules, which can damage the microcapsule walls, causing leakage of active ingredients and resulting in system turbidity, stratification, and compromised visual transparency and long-term stability.

[0005] Therefore, it is of great significance to develop a microcapsule sunscreen essence gel with high transparency, refreshing feel, high protection, and high stability. Summary of the Invention

[0006] This invention provides a microcapsule sunscreen essence gel with high transparency, a refreshing feel, high protection, and excellent stability. This invention solves the problem of poor compatibility between traditional sunscreen gel formulations and hydrogel microcapsules; traditional systems easily damage the microcapsule walls, causing leakage of active ingredients, which in turn leads to turbidity and stratification, resulting in a loss of transparent appearance and compromised long-term product stability.

[0007] To achieve the above objectives, the present invention provides the following technical solution: A sunscreen essence gel containing active ingredient microcapsules, comprising: a sunscreen gel and active ingredient microcapsules dispersed in the sunscreen gel; The sunscreen gel comprises an oil phase and an aqueous phase; the oil phase contains a hydrophilic resin-type silicone elastomer. The active ingredient microcapsules include a capsule core and a capsule wall encapsulating the capsule core; the capsule core contains an oil-phase dispersion system of silymarin.

[0008] Furthermore, the sunscreen essence gel contains the following components by mass fraction: 1-5% active ingredient microcapsules, and 95-99% sunscreen gel; Preferably, the sunscreen essence gel contains the following components by mass fraction: 3% active ingredient microcapsules and 97% sunscreen gel.

[0009] Furthermore, the oil phase of the sunscreen gel contains a hydrophilic resin-type silicone elastomer BELSIL® REG 1103 B, which is a compound containing polydimethylsiloxane, a polydimethylsiloxane / vinyltrimethylsiloxane silicate crosspolymer, and octyl polydimethylsiloxane ethoxyglucoside.

[0010] Furthermore, the weight ratio of the oil phase to the water phase in the sunscreen gel is 55-65:45-35; The oil phase components of the sunscreen gel include: 5-12 parts of 1.5cSt polydimethylsiloxane, 2-6 parts of cresoltrazol trisiloxane, 0.5-3 parts of trimethylsiloxysilicate, 0.5-3 parts of isoamyl p-methoxycinnamate, 0.1-0.5 parts of bisabolol, and 10-20 parts of BELSIL® REG 1103 B.

[0011] The aqueous phase component of the sunscreen gel includes: 4-8 parts of terephthalic acid dicamphor sulfonic acid, 5-8 parts of phenylbenzimidazole sulfonic acid, 2-8 parts of disodium phenylbenzimidazole tetrasulfonate, 1-5 parts of tromethamine, 1-5 parts of aminomethylpropanol, 2-8 parts of glycerin, and the remainder is water.

[0012] Furthermore, 0-2 parts of polysiloxane-15 can be added to the oil phase to correspondingly reduce the amount of water added to the aqueous phase.

[0013] Furthermore, the capsule wall of the active ingredient microcapsule comprises a hydrogel framework formed by agar and sodium alginate; Preferably, the capsule wall further comprises carmine and mica pearlescent powder.

[0014] Furthermore, the particle size of the active ingredient microcapsules is approximately 1-3 mm; Preferably, the oil phase dispersion system of silymarin in the capsule core uses glycerol stearate as the dispersion carrier; The mass fraction of silymarin in the oil phase dispersion system is 1-5%.

[0015] The present invention also proposes a method for preparing the above-mentioned sunscreen essence gel, comprising the following steps: S1 Preparation of oil phase: Mix and disperse the oil phase components evenly at room temperature to obtain the oil phase; S2 Preparation of aqueous phase: Mix and disperse the components of the aqueous phase evenly to obtain the aqueous phase; S3 Preparation of sunscreen gel: After confirming that both the oil phase and the water phase are transparent and the difference in their refractive indices is ≤0.005, the water phase is slowly added to the oil phase while stirring at 50~80 rpm and stirred evenly to obtain the sunscreen gel. S4 Preparation of active ingredient microcapsules: Core-shell hydrogel microcapsules encapsulating silymarin were prepared by concentric sandwich drop method; S5 Product Preparation: Add the active ingredient microcapsules to the sunscreen gel and mix well to obtain the product.

[0016] Furthermore, step S4 specifically includes: Agar and sodium alginate were added to an ethanol-water solution and stirred at a constant temperature of 70-80℃ for 0.5-1h to obtain the capsule wall fluid; Glyceryl stearate and silymarin are mixed and heated to 70-80℃ and stirred until homogenized. The mixture is then homogenized at 40-50MPa pressure for 3-5 minutes to obtain the core fluid. A double-layer concentric sandwich dropper is used to allow the capsule wall liquid to flow out simultaneously from the outer annular channel and the capsule core liquid from the inner central channel, forming a sandwich liquid column. After being cut into droplets, the liquid is cooled and solidified to obtain active ingredient microcapsules.

[0017] Furthermore, in the preparation method, 18-24 parts of agar, 6-10 parts of sodium alginate, 0.4-0.8 parts of carmine, and 0.4-0.8 parts of mica pearl powder are added to a 50% ethanol aqueous solution and stirred at a constant temperature of 70-80℃ for 0.5h to obtain the capsule wall liquid. Mix 6-9 parts of glyceryl stearate and 1-5 parts of silymarin, heat to 70°C and stir until homogeneous. Homogenize at 45 MPa for 3 minutes to obtain the core solution.

[0018] The technical solution of this invention has the following advantages: This invention combines a microcapsule protection system specifically designed for active ingredient stability with a gentle matrix constructed from the third-generation hydrophilic resin-type silicone elastomer BELSIL® REG 1103 B. BELSIL® REG 1103 B is a non-volatile, low-viscosity polydimethylsiloxane copolymer composed of organosilicon glucoside. It possesses self-emulsifying, water-retaining, and excellent spreadability properties, allowing for rapid spread on the skin after application, imparting a silky, moisturizing, refreshing, and easily spreadable premium feel to the formula, and achieving a unique watery texture. Simultaneously, the unique molecular structure of its organosilicon glucoside serves as a dedicated emulsification system for transparent sunscreen essence gels and is compatible with the microcapsule interface, constructing a gentle and stable interfacial protective environment on the microcapsule surface. This effectively and completely supports and protects the microcapsule structure, preventing microcapsule wall damage and leakage of internal sunscreen active ingredients.

[0019] This invention achieves simultaneous improvement in active ingredient storage stability and sun protection efficacy through the synergistic combination of a microcapsule protection system designed for active ingredient stability and a mild matrix constructed from the third-generation hydrophilic resin-type silicone elastomer BELSIL® REG 1103 B. It fundamentally solves the technical pain points of poor compatibility between traditional PEG emulsion systems and hydrogel microcapsules, which easily cause system turbidity and stratification, loss of transparency and deterioration of stability. Ultimately, it achieves a four-fold technological breakthrough: high formula transparency, high active ingredient stability, high sun protection efficacy and a refreshing and superior skin feel. Attached Figure Description

[0020] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0021] Figure 1 This is a product diagram of Embodiment 1 of the present invention. Detailed Implementation

[0022] The following embodiments are provided to better understand the present invention, but the following embodiments do not constitute a limitation on the content and scope of protection of the present invention. Any product that is the same as or similar to the present invention, derived by any person under the guidance of the present invention or by combining the features of the present invention with other prior art, falls within the scope of protection of the present invention.

[0023] Unless otherwise specified, all experimental steps or conditions in the examples were performed according to conventional experimental procedures and conditions in the art. Reagents or instruments whose manufacturers are not specified are all commercially available products.

[0024] Furthermore, regarding the numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Any stated value or intermediate value within a stated range, as well as each smaller range between any other stated value or intermediate value within said range, are also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0025] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar to or equivalent to those described herein may be used in the implementation or testing of this invention.

[0026] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.

[0027] Example 1. Preparation of microencapsulated sunscreen gel 1. Preparation of the oil phase 8% (by weight) of polydimethylsiloxane (XIAMETER™ PMX-200 Fluid, 1.5 cSt, purchased from Dow (Zhangjiagang) Investment Co., Ltd.), 3% (by weight) of cresoltrazolium trisiloxane (Crosorb D, purchased from Cropasse Co., Ltd.), and 1% (by weight) of trimethylsiloxysilicate (BELSIL® TMS 803, purchased from Wacker Chemie (China) Co., Ltd.) were added to an emulsifying tank and stirred at room temperature until the mixture was transparent and free of particles, thus obtaining phase A1.

[0028] 1% (by weight) of isoamyl p-methoxycinnamate (Neo Heliopan® E1000, purchased from Symrise Fragrance & Flavor (Nantong) Co., Ltd.), 0.2% (by weight) of bisabolol (Bisabolol rac., purchased from BASF (China) Co., Ltd.), and 15% (by weight) of polydimethylsiloxane, polydimethylsiloxane / vinyltrimethylsiloxane silicate crosspolymer, and octyl polydimethylsiloxane ethoxyglucoside (BELSIL® REG 1103B, purchased from Wacker Chemie (China) Co., Ltd.) were mixed evenly to obtain phase A2.

[0029] Add phase A2 to the emulsification pot containing phase A1, turn on the homogenizer, and homogenize and disperse at 1000 rpm for 5-10 minutes until the system is completely uniform, transparent and free of particles. Set aside to obtain the oil phase.

[0030] 2. Preparation of aqueous phase 12% (w / w) of terephthalimide dicamphor sulfonic acid (Crosorb T, purchased from Cropasse Co., Ltd.), 8% (w / w) of phenylbenzimidazole sulfonic acid (Neo Heliopan® Hydro, purchased from Symrise Fragrance & Flavor (Nantong) Co., Ltd.), 5% (w / w) of disodium phenyl dibenzimidazole tetrasulfonate (Neo Heliopan® AP, purchased from Symrise Fragrance & Flavor (Nantong) Co., Ltd.), 3% (w / w) of tromethamine (Tris Amino UltraPC, purchased from Yalu Chemical Trading (Shanghai) Co., Ltd.), 3% (w / w) of aminomethylpropanol (AMP-ULTRA™ PC1000, purchased from Yalu Chemical Trading (Shanghai) Co., Ltd.), and 32.8% (w / w) of water were added to an aqueous phase pot and dispersed and dissolved at 1000 rpm until transparent and free of particles to obtain phase B1.

[0031] In an aqueous phase pot containing phase B1, add 5% (by mass) of glycerol (refined glycerol, purchased from Wilmar Biotechnology (Shanghai) Co., Ltd.) and disperse evenly at 1000 rpm to obtain the aqueous phase.

[0032] 3. Preparation of sunscreen gel The appearance of both the oil phase and the aqueous phase was transparent, and the difference in refractive index between the oil phase and the aqueous phase was ≤0.005. The emulsification pot containing the oil phase was stirred (50-80 rpm), and the well-mixed aqueous phase was slowly pumped into the emulsification pot until all the aqueous phase was pumped out and stirred evenly to obtain the sunscreen gel.

[0033] 4. Preparation of active ingredient microcapsules The active ingredient microcapsules feature a core-shell bilayer structure, with a gentle, skin-friendly hydrogel as the capsule wall framework material. This structure not only possesses excellent shaping and shaping capabilities, resulting in highly regular capsule formation and resistance to breakage, but also conforms to the skin feel of skincare products, being lightweight and non-greasy, and suitable for various formulations such as lotions, creams, and sunscreens. The microcapsules contain an oil-phase encapsulated core dispersion system, stably encapsulating the functional active ingredient silymarin within the oil core. This effectively isolates silymarin from degradation by light, high temperature, and oxygen, significantly improving the photostability, thermal stability, and antioxidant storage stability of the active ingredient. Furthermore, this core-shell structure possesses external force-triggered rupture and release properties. During application and rubbing, the microcapsules gently rupture, releasing silymarin evenly and rapidly for effective penetration. This structure can be widely used in sun protection and repair, skin soothing, and anti-photoaging cosmetics.

[0034] Specific implementation method: 22 g of agar, 8 g of sodium alginate, 0.6 g of carmine, and 0.6 g of mica pearlescent powder were added to 350 mL of 50% (v / v) ethanol aqueous solution, heated to 70-80°C, and stirred continuously at a constant temperature for 0.5 h until homogeneous, to obtain the capsule wall liquid; 7.5 g of glyceryl stearate and 1.5 g of silymarin were mixed, heated to 70°C, stirred until homogeneous, and homogenized under a homogenization pressure of 45 MPa for 3 min. The core liquid was prepared; a concentric sandwich drop method was adopted, in which the fluid flow was controlled by a double-layer concentric sandwich dropper: the prepared hydrogel capsule wall liquid flowed out at a uniform speed from the outer annular channel of the dropper, and the core oil phase liquid flowed out at a uniform speed from the inner central channel of the dropper. The two phases of fluid merged synchronously to form a continuous sandwich liquid column; then the sandwich liquid column was cut at equal intervals by a cutter to form droplets. The droplets were placed in a cooling medium to cool down naturally and stand for a period of time, and gradually cross-linked and solidified, finally producing silymarin hydrogel microcapsules with uniform particle size, regular spherical shape, and a diameter of about 1.5 mm.

[0035] 5. Microcapsule sunscreen essence Adding 3% (by weight) of active ingredient microcapsules to a sunscreen gel yields a microcapsule sunscreen essence.

[0036] Example 2 1. Preparation of the oil phase 8% (by weight) of polydimethylsiloxane (XIAMETER™ PMX-200 Fluid, 1.5 cSt, purchased from Dow (Zhangjiagang) Investment Co., Ltd.), 3% (by weight) of cresoltrazolium trisiloxane (Crosorb D, purchased from Cropasse Co., Ltd.), and 1% (by weight) of trimethylsiloxysilicate (BELSIL® TMS 803, purchased from Wacker Chemie (China) Co., Ltd.) were added to an emulsifying tank and stirred at room temperature until the mixture was transparent and free of particles, thus obtaining phase A1.

[0037] 1% (by weight) of isoamyl p-methoxycinnamate (Neo Heliopan® E1000, purchased from Symrise Fragrance & Flavor (Nantong) Co., Ltd.), 2% (by weight) of polysiloxane-15 (PARSOL®: SLX, purchased from DSM Vitamins (Shanghai) Co., Ltd.), 0.2% (by weight) of bisabolol (Bisabolol rac., purchased from BASF (China) Co., Ltd.), and 15% (by weight) of polydimethylsiloxane, polydimethylsiloxane / vinyltrimethylsiloxane silicate crosspolymer, and octyl polydimethylsiloxane ethoxyglucoside (BELSIL® REG 1103 B, purchased from Wacker Chemie (China) Co., Ltd.) were mixed evenly to obtain phase A2.

[0038] Add phase A2 to the emulsification pot containing phase A1, turn on the homogenizer, and homogenize and disperse at 1000 rpm for 5-10 minutes until the system is completely uniform, transparent and free of particles. Set aside to obtain the oil phase.

[0039] 2. Preparation of aqueous phase 12% (w / w) of terephthalimide dicamphor sulfonic acid (Crosorb T, purchased from Cropasse Co., Ltd.), 8% (w / w) of phenylbenzimidazole sulfonic acid (Neo Heliopan® Hydro, purchased from Symrise Fragrance & Flavor (Nantong) Co., Ltd.), 5% (w / w) of disodium phenyl dibenzimidazole tetrasulfonate (Neo Heliopan® AP, purchased from Symrise Fragrance & Flavor (Nantong) Co., Ltd.), 3% (w / w) of tromethamine (Tris Amino UltraPC, purchased from Yalu Chemical Trading (Shanghai) Co., Ltd.), 3% (w / w) of aminomethylpropanol (AMP-ULTRA™ PC1000, purchased from Yalu Chemical Trading (Shanghai) Co., Ltd.), and 30.8% (w / w) of water were added to an aqueous phase pot and dispersed and dissolved at 1000 rpm until transparent and free of particles to obtain phase B1.

[0040] In an aqueous phase pot containing phase B1, add 5% (by mass) of glycerol (refined glycerol, purchased from Wilmar Biotechnology (Shanghai) Co., Ltd.) and disperse evenly at 1000 rpm to obtain the aqueous phase.

[0041] 3. Preparation of sunscreen gel The appearance of both the oil phase and the aqueous phase was transparent, and the difference in refractive index between the oil phase and the aqueous phase was ≤0.005. The emulsification pot containing the oil phase was stirred (50-80 rpm). The well-mixed aqueous phase was slowly pumped into the emulsification pot until all the aqueous phase was pumped out and stirred evenly to obtain the sunscreen gel.

[0042] 4. Preparation of active ingredient microcapsules The active ingredient microcapsules feature a core-shell bilayer structure, with a gentle, skin-friendly hydrogel as the capsule wall framework material. This structure not only possesses excellent shaping and shaping capabilities, resulting in highly regular capsule formation and resistance to breakage, but also conforms to the skin feel of skincare products, being lightweight and non-greasy, and suitable for various formulations such as lotions, creams, and sunscreens. The microcapsules contain an oil-phase encapsulated core dispersion system, stably encapsulating the functional active ingredient silymarin within the oil core. This effectively isolates silymarin from degradation by light, high temperature, and oxygen, significantly improving the photostability, thermal stability, and antioxidant storage stability of the active ingredient. Furthermore, this core-shell structure possesses external force-triggered rupture and release properties. During application and rubbing, the microcapsules gently rupture, releasing silymarin evenly and rapidly for effective penetration. This structure can be widely used in sun protection and repair, skin soothing, and anti-photoaging cosmetics.

[0043] Specific implementation method: 22 g of agar, 8 g of sodium alginate, 0.6 g of carmine, and 0.6 g of mica pearlescent powder were added to 350 mL of 50% (v / v) ethanol aqueous solution, heated to 70-80°C, and stirred continuously at a constant temperature for 0.5 h until homogeneous, to obtain the capsule wall liquid; 7.5 g of glyceryl stearate and 1.5 g of silymarin were mixed, heated to 70°C, stirred until homogeneous, and homogenized under a homogenization pressure of 45 MPa for 3 min. The core liquid was prepared; a concentric sandwich drop method was adopted, in which the fluid flow was controlled by a double-layer concentric sandwich dropper: the prepared hydrogel capsule wall liquid flowed out at a uniform speed from the outer annular channel of the dropper, and the core oil phase liquid flowed out at a uniform speed from the inner central channel of the dropper. The two phases of fluid merged synchronously to form a continuous sandwich liquid column; then the sandwich liquid column was cut at equal intervals by a cutter to form droplets. The droplets were placed in a cooling medium to cool down naturally and stand for a period of time, and gradually cross-linked and solidified, finally producing silymarin hydrogel microcapsules with uniform particle size, regular spherical shape, and a diameter of about 1.5 mm.

[0044] 5. Microcapsule sunscreen essence Adding 3% (by weight) of active ingredient microcapsules to a sunscreen gel yields a microcapsule sunscreen essence.

[0045] Comparative Example 1 1. Preparation of the oil phase 8% (by weight) of polydimethylsiloxane (XIAMETER™ PMX-200 Fluid, 1.5 cSt, purchased from Dow (Zhangjiagang) Investment Co., Ltd.), 3% (by weight) of cresoltrazolium trisiloxane (Crosorb D, purchased from Cropasse Co., Ltd.), and 1% (by weight) of trimethylsiloxysilicate (BELSIL® TMS 803, purchased from Wacker Chemie (China) Co., Ltd.) were added to an emulsifying tank and stirred at room temperature until the mixture was transparent and free of particles, thus obtaining phase A1.

[0046] 1% (by weight) of isoamyl p-methoxycinnamate (Neo Heliopan® E1000, purchased from Symrise Fragrance & Flavor (Nantong) Co., Ltd.), 0.2% (by weight) of bisabolol (Bisabolol rac., purchased from BASF (China) Co., Ltd.), and 3% (by weight) of lauryl PEG-9 polydimethylsiloxane (KF-6038, purchased from Shin-Etsu Silicon International Trading (Shanghai) Co., Ltd.) were mixed evenly to obtain phase A2.

[0047] Add phase A2 to the emulsification pot containing phase A1, turn on the homogenizer, and homogenize and disperse at 1000 rpm for 5-10 minutes until the system is completely uniform, transparent and free of particles. Set aside to obtain the oil phase.

[0048] 2. Preparation of aqueous phase 12% (w / w) of terephthalimide dicamphor sulfonic acid (Crosorb T, purchased from Cropasse Co., Ltd.), 8% (w / w) of phenylbenzimidazole sulfonic acid (Neo Heliopan® Hydro, purchased from Symrise Fragrance & Flavor (Nantong) Co., Ltd.), 5% (w / w) of disodium phenyl dibenzimidazole tetrasulfonate (Neo Heliopan® AP, purchased from Symrise Fragrance & Flavor (Nantong) Co., Ltd.), 3% (w / w) of tromethamine (Tris Amino UltraPC, purchased from Yalu Chemical Trading (Shanghai) Co., Ltd.), 3% (w / w) of aminomethylpropanol (AMP-ULTRA™ PC1000, purchased from Yalu Chemical Trading (Shanghai) Co., Ltd.), and 44.8% (w / w) of water were added to an aqueous phase pot and dispersed and dissolved at 1000 rpm until transparent and free of particles to obtain phase B1.

[0049] In an aqueous phase pot containing phase B1, add 5% (by mass) of glycerol (refined glycerol, purchased from Wilmar Biotechnology (Shanghai) Co., Ltd.) and disperse evenly at 1000 rpm to obtain the aqueous phase.

[0050] 3. Preparation of sunscreen gel The appearance of both the oil phase and the aqueous phase was transparent, and the difference in refractive index between the oil phase and the aqueous phase was ≤0.005. The emulsification pot containing the oil phase was stirred (50-80 rpm). The well-mixed aqueous phase was slowly pumped into the emulsification pot until all the aqueous phase was pumped out and stirred evenly to obtain the sunscreen gel.

[0051] 4. Preparation of active ingredient microcapsules The active ingredient microcapsules feature a core-shell bilayer structure, with a gentle, skin-friendly hydrogel as the capsule wall framework material. This structure not only possesses excellent shaping and shaping capabilities, resulting in highly regular capsule formation and resistance to breakage, but also conforms to the skin feel of skincare products, being lightweight and non-greasy, and suitable for various formulations such as lotions, creams, and sunscreens. The microcapsules contain an oil-phase encapsulated core dispersion system, stably encapsulating the functional active ingredient silymarin within the oil core. This effectively isolates silymarin from degradation by light, high temperature, and oxygen, significantly improving the photostability, thermal stability, and antioxidant storage stability of the active ingredient. Furthermore, this core-shell structure possesses external force-triggered rupture and release properties. During application and rubbing, the microcapsules gently rupture, releasing silymarin evenly and rapidly for effective penetration. This structure can be widely used in sun protection and repair, skin soothing, and anti-photoaging cosmetics.

[0052] Specific implementation method: 22 g of agar, 8 g of sodium alginate, 0.6 g of carmine, and 0.6 g of mica pearlescent powder were added to 350 mL of 50% (v / v) ethanol aqueous solution, heated to 70-80°C, and stirred continuously at a constant temperature for 0.5 h until homogeneous, to obtain the capsule wall liquid; 7.5 g of glyceryl stearate and 1.5 g of silymarin were mixed, heated to 70°C, stirred until homogeneous, and homogenized under a homogenization pressure of 45 MPa for 3 min. The core liquid was prepared; a concentric sandwich drop method was adopted, in which the fluid flow was controlled by a double-layer concentric sandwich dropper: the prepared hydrogel capsule wall liquid flowed out at a uniform speed from the outer annular channel of the dropper, and the core oil phase liquid flowed out at a uniform speed from the inner central channel of the dropper. The two phases of fluid merged synchronously to form a continuous sandwich liquid column; then the sandwich liquid column was cut at equal intervals by a cutter to form droplets. The droplets were placed in a cooling medium to cool down naturally and stand for a period of time, and gradually cross-linked and solidified, finally producing silymarin hydrogel microcapsules with uniform particle size, regular spherical shape, and a diameter of about 1.5 mm.

[0053] 5. Microcapsule sunscreen essence Adding 3% (by weight) of active ingredient microcapsules to a sunscreen gel yields a microcapsule sunscreen essence.

[0054] Comparative Example 2 1. Preparation of the oil phase 8% (by weight) of polydimethylsiloxane (XIAMETER™ PMX-200 Fluid, 1.5 cSt, purchased from Dow (Zhangjiagang) Investment Co., Ltd.), 3% (by weight) of cresoltrazolium trisiloxane (Crosorb D, purchased from Cropasse Co., Ltd.), and 1% (by weight) of trimethylsiloxysilicate (BELSIL® TMS 803, purchased from Wacker Chemie (China) Co., Ltd.) were added to an emulsifying tank and stirred at room temperature until the mixture was transparent and free of particles, thus obtaining phase A1.

[0055] 1% (by weight) of isoamyl p-methoxycinnamate (Neo Heliopan® E1000, purchased from Symrise Fragrance & Flavor (Nantong) Co., Ltd.), 0.2% (by weight) of bisabolol (Bisabolol rac., purchased from BASF (China) Co., Ltd.), and 3% (by weight) of polydimethylsiloxane and polydimethylsiloxane PEG-10 / 15 crosspolymer (KSG-210, purchased from Shin-Etsu Silicon International Trading (Shanghai) Co., Ltd.) were mixed evenly to obtain phase A2.

[0056] Add phase A2 to the emulsification pot containing phase A1, turn on the homogenizer, and homogenize and disperse at 1000 rpm for 5-10 minutes until the system is completely uniform, transparent and free of particles. Set aside to obtain the oil phase.

[0057] 2. Preparation of aqueous phase 12% (w / w) of terephthalimide dicamphor sulfonic acid (Crosorb T, purchased from Cropasse Co., Ltd.), 8% (w / w) of phenylbenzimidazole sulfonic acid (Neo Heliopan® Hydro, purchased from Symrise Fragrance & Flavor (Nantong) Co., Ltd.), 5% (w / w) of disodium phenyl dibenzimidazole tetrasulfonate (Neo Heliopan® AP, purchased from Symrise Fragrance & Flavor (Nantong) Co., Ltd.), 3% (w / w) of tromethamine (Tris Amino UltraPC, purchased from Yalu Chemical Trading (Shanghai) Co., Ltd.), 3% (w / w) of aminomethylpropanol (AMP-ULTRA™ PC1000, purchased from Yalu Chemical Trading (Shanghai) Co., Ltd.), and 44.8% (w / w) of water were added to an aqueous phase pot and dispersed and dissolved at 1000 rpm until transparent and free of particles to obtain phase B1.

[0058] In an aqueous phase pot containing phase B1, add 5% (by mass) of glycerol (refined glycerol, purchased from Wilmar Biotechnology (Shanghai) Co., Ltd.) and disperse evenly at 1000 rpm to obtain the aqueous phase.

[0059] 3. Preparation of sunscreen gel The appearance of both the oil phase and the aqueous phase was transparent, and the difference in refractive index between the oil phase and the aqueous phase was ≤0.005. The emulsification pot containing the oil phase was stirred (50-80 rpm). The well-mixed aqueous phase was slowly pumped into the emulsification pot until all the aqueous phase was pumped out and stirred evenly to obtain the sunscreen gel.

[0060] 4. Preparation of active ingredient microcapsules The active ingredient microcapsules feature a core-shell bilayer structure, with a gentle, skin-friendly hydrogel as the capsule wall framework material. This structure not only possesses excellent shaping and shaping capabilities, resulting in highly regular capsule formation and resistance to breakage, but also conforms to the skin feel of skincare products, being lightweight and non-greasy, and suitable for various formulations such as lotions, creams, and sunscreens. The microcapsules contain an oil-phase encapsulated core dispersion system, stably encapsulating the functional active ingredient silymarin within the oil core. This effectively isolates silymarin from degradation by light, high temperature, and oxygen, significantly improving the photostability, thermal stability, and antioxidant storage stability of the active ingredient. Furthermore, this core-shell structure possesses external force-triggered rupture and release properties. During application and rubbing, the microcapsules gently rupture, releasing silymarin evenly and rapidly for effective penetration. This structure can be widely used in sun protection and repair, skin soothing, and anti-photoaging cosmetics.

[0061] Specific implementation method: 22 g of agar, 8 g of sodium alginate, 0.6 g of carmine, and 0.6 g of mica pearlescent powder were added to 350 mL of 50% (v / v) ethanol aqueous solution, heated to 70-80°C, and stirred continuously at a constant temperature for 0.5 h until homogeneous, to obtain the capsule wall liquid; 7.5 g of glyceryl stearate and 1.5 g of silymarin were mixed, heated to 70°C, stirred until homogeneous, and homogenized under a homogenization pressure of 45 MPa for 3 min. The core liquid was prepared; a concentric sandwich drop method was adopted, in which the fluid flow was controlled by a double-layer concentric sandwich dropper: the prepared hydrogel capsule wall liquid flowed out at a uniform speed from the outer annular channel of the dropper, and the core oil phase liquid flowed out at a uniform speed from the inner central channel of the dropper. The two phases of fluid merged synchronously to form a continuous sandwich liquid column; then the sandwich liquid column was cut at equal intervals by a cutter to form droplets. The droplets were placed in a cooling medium to cool down naturally and stand for a period of time, and gradually cross-linked and solidified, finally producing silymarin hydrogel microcapsules with uniform particle size, regular spherical shape, and a diameter of about 1.5 mm.

[0062] 5. Microcapsule sunscreen essence Adding 3% (by weight) of active ingredient microcapsules to a sunscreen gel yields a microcapsule sunscreen essence.

[0063] Comparative Example 3 1. Preparation of the oil phase 8% (by weight) of polydimethylsiloxane (XIAMETER™ PMX-200 Fluid, 1.5 cSt, purchased from Dow (Zhangjiagang) Investment Co., Ltd.), 3% (by weight) of cresoltrazolium trisiloxane (Crosorb D, purchased from Cropasse Co., Ltd.), and 1% (by weight) of trimethylsiloxysilicate (BELSIL® TMS 803, purchased from Wacker Chemie (China) Co., Ltd.) were added to an emulsifying tank and stirred at room temperature until the mixture was transparent and free of particles, thus obtaining phase A1.

[0064] 1% (by weight) of isoamyl p-methoxycinnamate (Neo Heliopan® E1000, purchased from Symrise Fragrance & Flavor (Nantong) Co., Ltd.), 0.2% (by weight) of bisabolol (Bisabolol rac., purchased from BASF (China) Co., Ltd.), and 15% (by weight) of C13-16 isoparaffins, polydimethylsiloxane / vinyl polydimethylsiloxane crosspolymer, and polydimethylsiloxane (HARMONIE SLEEKIONOC GEL, purchased from Momentive (Shanghai) Trading Co., Ltd.) were mixed evenly to obtain phase A2.

[0065] Add phase A2 to the emulsification pot containing phase A1, turn on the homogenizer, and homogenize and disperse at 1000 rpm for 5-10 minutes until the system is completely uniform, transparent and free of particles. Set aside to obtain the oil phase.

[0066] 2. Preparation of aqueous phase 12% (w / w) of terephthalimide dicamphor sulfonic acid (Crosorb T, purchased from Cropasse Co., Ltd.), 8% (w / w) of phenylbenzimidazole sulfonic acid (Neo Heliopan® Hydro, purchased from Symrise Fragrance & Flavor (Nantong) Co., Ltd.), 5% (w / w) of disodium phenyl dibenzimidazole tetrasulfonate (Neo Heliopan® AP, purchased from Symrise Fragrance & Flavor (Nantong) Co., Ltd.), 3% (w / w) of tromethamine (Tris Amino UltraPC, purchased from Yalu Chemical Trading (Shanghai) Co., Ltd.), 3% (w / w) of aminomethylpropanol (AMP-ULTRA™ PC1000, purchased from Yalu Chemical Trading (Shanghai) Co., Ltd.), and 32.8% (w / w) of water were added to an aqueous phase pot and dispersed and dissolved at 1000 rpm until transparent and free of particles to obtain phase B1.

[0067] In an aqueous phase pot containing phase B1, add 5% (by mass) of glycerol (refined glycerol, purchased from Wilmar Biotechnology (Shanghai) Co., Ltd.) and disperse evenly at 1000 rpm to obtain the aqueous phase.

[0068] 3. Preparation of sunscreen gel The appearance of both the oil phase and the aqueous phase was transparent, and the difference in refractive index between the oil phase and the aqueous phase was ≤0.005. The emulsification pot containing the oil phase was stirred (50-80 rpm). The well-mixed aqueous phase was slowly pumped into the emulsification pot until all the aqueous phase was pumped out and stirred evenly to obtain the sunscreen gel.

[0069] 4. Preparation of active ingredient microcapsules The active ingredient microcapsules feature a core-shell bilayer structure, with a gentle, skin-friendly hydrogel as the capsule wall framework material. This structure not only possesses excellent shaping and shaping capabilities, resulting in highly regular capsule formation and resistance to breakage, but also conforms to the skin feel of skincare products, being lightweight and non-greasy, and suitable for various formulations such as lotions, creams, and sunscreens. The microcapsules contain an oil-phase encapsulated core dispersion system, stably encapsulating the functional active ingredient silymarin within the oil core. This effectively isolates silymarin from degradation by light, high temperature, and oxygen, significantly improving the photostability, thermal stability, and antioxidant storage stability of the active ingredient. Furthermore, this core-shell structure possesses external force-triggered rupture and release properties. During application and rubbing, the microcapsules gently rupture, releasing silymarin evenly and rapidly for effective penetration. This structure can be widely used in sun protection and repair, skin soothing, and anti-photoaging cosmetics.

[0070] Specific implementation method: 22 g of agar, 8 g of sodium alginate, 0.6 g of carmine, and 0.6 g of mica pearlescent powder were added to 350 mL of 50% (v / v) ethanol aqueous solution, heated to 70-80°C, and stirred continuously at a constant temperature for 0.5 h until homogeneous, to obtain the capsule wall liquid; 7.5 g of glyceryl stearate and 1.5 g of silymarin were mixed, heated to 70°C, stirred until homogeneous, and homogenized under a homogenization pressure of 45 MPa for 3 min. The core liquid was prepared; a concentric sandwich drop method was adopted, in which the fluid flow was controlled by a double-layer concentric sandwich dropper: the prepared hydrogel capsule wall liquid flowed out at a uniform speed from the outer annular channel of the dropper, and the core oil phase liquid flowed out at a uniform speed from the inner central channel of the dropper. The two phases of fluid merged synchronously to form a continuous sandwich liquid column; then the sandwich liquid column was cut at equal intervals by a cutter to form droplets. The droplets were placed in a cooling medium to cool down naturally and stand for a period of time, and gradually cross-linked and solidified, finally producing silymarin hydrogel microcapsules with uniform particle size, regular spherical shape, and a diameter of about 1.5 mm.

[0071] 5. Microcapsule sunscreen essence Adding 3% (by weight) of active ingredient microcapsules to a sunscreen gel yields a microcapsule sunscreen essence.

[0072] Comparative Example 4 1. Preparation of the oil phase 8% (by weight) of polydimethylsiloxane (XIAMETER™ PMX-200 Fluid, 1.5 cSt, purchased from Dow (Zhangjiagang) Investment Co., Ltd.), 3% (by weight) of cresoltrazolium trisiloxane (Crosorb D, purchased from Cropasse Co., Ltd.), and 1% (by weight) of trimethylsiloxysilicate (BELSIL® TMS 803, purchased from Wacker Chemie (China) Co., Ltd.) were added to an emulsifying tank and stirred at room temperature until the mixture was transparent and free of particles, thus obtaining phase A1.

[0073] 1% (by weight) of isoamyl p-methoxycinnamate (Neo Heliopan® E1000, purchased from Symrise Fragrance & Flavor (Nantong) Co., Ltd.), 0.2% (by weight) of bisabolol (Bisabolol rac., purchased from BASF (China) Co., Ltd.), and 15% (by weight) of polydimethylsiloxane, polydimethylsiloxane / vinyltrimethylsiloxane silicate crosspolymer, and octyl polydimethylsiloxane ethoxyglucoside (BELSIL® REG 1103B, purchased from Wacker Chemie (China) Co., Ltd.) were mixed evenly to obtain phase A2.

[0074] Add phase A2 to the emulsification pot containing phase A1, turn on the homogenizer, and homogenize and disperse at 1000 rpm for 5-10 minutes until the system is completely uniform, transparent and free of particles. Set aside to obtain the oil phase.

[0075] 2. Preparation of aqueous phase 12% (w / w) of terephthalimide dicamphor sulfonic acid (Crosorb T, purchased from Cropasse Co., Ltd.), 8% (w / w) of phenylbenzimidazole sulfonic acid (Neo Heliopan® Hydro, purchased from Symrise Fragrance & Flavor (Nantong) Co., Ltd.), 5% (w / w) of disodium phenyl dibenzimidazole tetrasulfonate (Neo Heliopan® AP, purchased from Symrise Fragrance & Flavor (Nantong) Co., Ltd.), 3% (w / w) of tromethamine (Tris Amino UltraPC, purchased from Yalu Chemical Trading (Shanghai) Co., Ltd.), 3% (w / w) of aminomethylpropanol (AMP-ULTRA™ PC1000, purchased from Yalu Chemical Trading (Shanghai) Co., Ltd.), and 32.8% (w / w) of water were added to an aqueous phase pot and dispersed and dissolved at 1000 rpm until transparent and free of particles to obtain phase B1.

[0076] In an aqueous phase pot containing phase B1, add 5% (by mass) of glycerol (refined glycerol, purchased from Wilmar Biotechnology (Shanghai) Co., Ltd.) and disperse evenly at 1000 rpm to obtain the aqueous phase.

[0077] 3. Preparation of sunscreen gel The appearance of both the oil phase and the aqueous phase was transparent, and the difference in refractive index between the oil phase and the aqueous phase was ≤0.005. The emulsification pot containing the oil phase was stirred (50-80 rpm). The well-mixed aqueous phase was slowly pumped into the emulsification pot until all the aqueous phase was pumped out and stirred evenly to obtain the sunscreen gel.

[0078] 4. Microcapsule sunscreen essence Add 3% (by weight) of free silymarin powder (fully dispersed in propylene glycol) to the sunscreen gel to obtain microcapsule sunscreen essence.

[0079] Comparative Example 5 1. Preparation of the oil phase 8% (by weight) of polydimethylsiloxane (XIAMETER™ PMX-200 Fluid, 1.5 cSt, purchased from Dow (Zhangjiagang) Investment Co., Ltd.), 3% (by weight) of cresoltrazolium trisiloxane (Crosorb D, purchased from Cropasse Co., Ltd.), and 1% (by weight) of trimethylsiloxysilicate (BELSIL® TMS 803, purchased from Wacker Chemie (China) Co., Ltd.) were added to an emulsifying tank and stirred at room temperature until the mixture was transparent and free of particles, thus obtaining phase A1.

[0080] 1% (by weight) of isoamyl p-methoxycinnamate (Neo Heliopan® E1000, purchased from Symrise Fragrance & Flavor (Nantong) Co., Ltd.), 0.2% (by weight) of bisabolol (Bisabolol rac., purchased from BASF (China) Co., Ltd.), and 15% (by weight) of polydimethylsiloxane, polydimethylsiloxane / vinyltrimethylsiloxane silicate crosspolymer, and octyl polydimethylsiloxane ethoxyglucoside (BELSIL® REG 1103B, purchased from Wacker Chemie (China) Co., Ltd.) were mixed evenly to obtain phase A2.

[0081] Add phase A2 to the emulsification pot containing phase A1, turn on the homogenizer, and homogenize and disperse at 1000 rpm for 5-10 minutes until the system is completely uniform, transparent and free of particles. Set aside to obtain the oil phase.

[0082] 2. Preparation of aqueous phase 12% (w / w) of terephthalimide dicamphor sulfonic acid (Crosorb T, purchased from Cropasse Co., Ltd.), 8% (w / w) of phenylbenzimidazole sulfonic acid (Neo Heliopan® Hydro, purchased from Symrise Fragrance & Flavor (Nantong) Co., Ltd.), 5% (w / w) of disodium phenyl dibenzimidazole tetrasulfonate (Neo Heliopan® AP, purchased from Symrise Fragrance & Flavor (Nantong) Co., Ltd.), 3% (w / w) of tromethamine (Tris Amino UltraPC, purchased from Yalu Chemical Trading (Shanghai) Co., Ltd.), 3% (w / w) of aminomethylpropanol (AMP-ULTRA™ PC1000, purchased from Yalu Chemical Trading (Shanghai) Co., Ltd.), and 32.8% (w / w) of water were added to an aqueous phase pot and dispersed and dissolved at 1000 rpm until transparent and free of particles to obtain phase B1.

[0083] In an aqueous phase pot containing phase B1, add 5% (by mass) of glycerol (refined glycerol, purchased from Wilmar Biotechnology (Shanghai) Co., Ltd.) and disperse evenly at 1000 rpm to obtain the aqueous phase.

[0084] 3. Preparation of sunscreen gel The appearance of both the oil phase and the aqueous phase was transparent, and the difference in refractive index between the oil phase and the aqueous phase was ≤0.005. The emulsification pot containing the oil phase was stirred (300-600 rpm). The well-mixed aqueous phase was slowly pumped into the emulsification pot until all the aqueous phase was pumped out and stirred evenly to obtain the sunscreen gel.

[0085] 4. Microcapsule sunscreen essence Add 3% (by weight) of water to the sunscreen gel to obtain a microcapsule sunscreen essence.

[0086] Experimental Example 1. System stability, transparency testing, and detection of active ingredient retention rate. (1) System stability: The microcapsule sunscreen essences prepared in Examples 1-2 and Comparative Examples 1-5 were observed for 3 months at -15℃, 5℃, 25℃, 40℃, and 45℃ respectively. After three months, if the stability showed no abnormalities under all temperature conditions, it was marked "√"; if it failed under one temperature condition, it was marked "×"; or if the microcapsule wall was damaged, the active ingredients leaked, causing the system to become turbid and layered, destroying the transparent visual characteristics, it indicated that the stability had not passed.

[0087] (2) Transparency test: Take 50 mL of each of the sunscreen essence prepared in Examples 1-2 and Comparative Examples 1-5, and use a UV-Vis spectrophotometer to measure the transmittance of the sample at a wavelength of 550 nm (with deionized water as a reference and a sample thickness of 1 cm). Transmittance ≥ 90% is considered transparent.

[0088] (3) Retention rate of active ingredients: Take 50 mL of each of the sunscreen microcapsule essence samples prepared in Examples 1-2 and Comparative Examples 1-4, and seal them in transparent high-temperature resistant polypropylene sampling bottles; store all samples in a 45℃ constant temperature and light-proof oven for 60 days, and take samples on day 0 (initial) and day 60 (end); accurately weigh 5.0 g of the sample to be tested, and extract silymarin by low-temperature ultrasonic lysis with anhydrous ethanol, and quantitatively detect the silymarin content at each time point by liquid chromatography (HPLC); retention rate = measured content after high-temperature storage ÷ initial reference content × 100%, and compare the 60-day active ingredient retention data of each group of samples to evaluate the protective effect of microcapsules on silymarin.

[0089] Results: The test results are shown in Table 1.

[0090] Table 1

[0091] Table 1 shows that both Examples 1 and 2 exhibited good system stability after being placed under different temperature conditions for 3 months, with no obvious stratification, precipitation, microcapsule rupture, or water loss. At the same time, the light transmittance reached 97.8% and 96.4%, respectively, indicating that the products have good transparency and applicability. After being placed under accelerated conditions at 45℃ in the dark for 60 days, the active ingredient retention rates still reached 93.6% and 92.9%, respectively, which were significantly better than several comparative examples.

[0092] 2. Synergistic effect test of SPF sun protection value (1) Test substances: Example 1, Comparative Examples 1-5 and Example 1 and Comparative Examples 1-5 after being stored at 45°C for 60 days in the dark; (2) Reference standard: SPF value 16.1±2.4, prepared according to the standard formula of high SPF standard (P2) in the "Cosmetic Safety Technical Specifications" (2015 edition); (3) Subjects: 3 people in each group, who meet the criteria for voluntary inclusion; (4) Test method: SPF human test shall be conducted in accordance with the Cosmetic Safety Technical Specifications (2015 edition).

[0093] The results are shown in Table 2.

[0094] Table 2

[0095] Table 2 shows that Example 1 has a higher SPF value both immediately and after heat-resistant storage than Comparative Examples 1-5, indicating that the "microencapsulation protection" and "silicon elastic matrix (BELSIL® REG 1103 B)" in Example 1 have a good synergistic effect.

[0096] 3. Safety testing of active ingredients – microencapsulated sustained release (1) Test substances: Examples 1-2, Comparative Example 4; (2) Negative control: blank control; (3) Subjects: A total of 30 subjects, who met the criteria for voluntary selection.

[0097] (4) Test method: The test was conducted according to the method of human skin patch test in the "Cosmetic Safety Technical Specifications" (2015 edition). Approximately 0.020-0.025g of the sample (test substance) was placed in the patch tester and applied to the back of the subject with hypoallergenic adhesive tape. The test substance was removed after 24 hours. Skin reaction was observed at 0.5h, 24h and 48h after removal. The skin reaction grading standard in the current effective technical specifications (as shown in Table 3) was used, and the results were recorded.

[0098] Table 3. Grading Criteria for Skin Reaction in Closed Patch Tests

[0099] Results: The test results are shown in Table 4.

[0100] Table 4

[0101] Table 4 shows that the microcapsule sunscreen essences prepared in Examples 1-2 all showed negative reactions at 30 min, 24 h, and 48 h after the test, with no irritation or erythema. In contrast, the sunscreen essence prepared in Comparative Example 4, whose active ingredients were not encapsulated, showed a grade 1 skin adverse reaction in 1 out of 30 participants, and a grade 2 skin adverse reaction in 1 out of 30 participants. This indicates that the microcapsule sunscreen essence prepared according to this invention is non-irritating and shows no positive reactions on the skin, proving that the product is safer, less irritating, and gentler.

[0102] 4. Skin feel test Thirty volunteers were recruited. A 0.2 mL sample was taken from each participant and applied to the inside of the arm in circular motions 10 times. The spreadability was evaluated during the application process. After standing for 2 minutes, the oiliness and stickiness were assessed, and the overall skin feel score was calculated. The scoring criteria are shown in Table 5.

[0103] Table 5

[0104] Results: The test results are shown in Table 6.

[0105] Table 6

[0106] In summary, the experimental results clearly confirm the expected conclusion of this invention: "microencapsulation protection" and "silicone matrix (BELSIL® REG 1103 B)" have a significant synergistic effect in improving the stability of active ingredients and sun protection efficacy, achieving a technical effect of "1+1>2". Specific data support this conclusion as follows: 1. In terms of the stability of the active ingredient, the two work synergistically to provide a protective effect that goes beyond simple addition.

[0107] Data shows that after 60 days of accelerated stability testing at 45°C, Example 1, which uses "modified silicon bomb + active ingredient microcapsules", achieved a retention rate of 93.6% for the key active ingredient (silymarin). This value is not only significantly higher than that of Comparative Example 4 (67.33%), which uses "silicon bomb matrix + free active ingredient", demonstrating the necessity of microcapsule protection, but also significantly higher than that of Comparative Examples 1-3 (89.67%, 82.06%, and 83.77%), which use "traditional matrix + active ingredient microcapsules".

[0108] Synergy analysis: This gap indicates that the BELSIL® REG 1103 B silica matrix is ​​not merely an inert carrier; its mild interfacial properties and steric stabilizing effect create a superior external environment for the agar microcapsules, further slowing down the degradation rate of the active ingredients within the microcapsules under thermal stress, thus producing a synergistic stabilizing effect.

[0109] 2. In terms of sun protection efficacy (SPF value), the combination of the two produces a dual synergy of immediate enhancement and long-lasting stability.

[0110] Synergistic effect of immediate enhancement: The initial SPF value of Example 1 (microcapsules + modified silicone emulsion) reached 56.3, which is higher than that of Comparative Example 5 (46.8) containing only chemical sunscreen agents, and also higher than that of Comparative Examples 1-3 (52.3, 52.9, 53.4) of "microcapsules + silicone emulsion / PEG emulsion system" or Comparative Example 4 (50.2) of "silicone emulsion only + free matter". This indicates that the active ingredient microcapsules, which are properly protected by the silicone emulsion matrix, can effectively contribute their auxiliary protective capabilities such as antioxidant properties in the formulation, creating a synergistic effect with the basic sunscreen system and enhancing the immediate protective strength of the product.

[0111] Long-lasting and stable synergy: After 60 days of heat storage, the SPF retention rate of Example 1 reached 96.6%, with a significantly lower decay rate than Comparative Example 4 (degradation of free active ingredients leading to a decrease in SPF retention rate) and superior to Comparative Examples 1-3 (matrix instability leading to a decrease in SPF retention rate). This demonstrates that "microencapsulation protection" ensures the long-lasting effect of the active ingredients, while the "silicone matrix" maintains the integrity of the microcapsules and the entire sunscreen film. The two work together to achieve a synergistic effect in maintaining long-lasting sun protection efficacy.

[0112] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A sunscreen essence gel containing active ingredient microcapsules, characterized in that, include: Sunscreen gel and active ingredient microcapsules dispersed in the sunscreen gel; The sunscreen gel comprises an oil phase and an aqueous phase; the oil phase contains a hydrophilic resin-type silicone elastomer. The active ingredient microcapsules include a capsule core and a capsule wall encapsulating the capsule core; the capsule core contains an oil-phase dispersion system of silymarin.

2. The sunscreen essence gel according to claim 1, characterized in that, The sunscreen essence gel contains the following components by mass fraction: 1-5% active ingredient microcapsules, and 95-99% sunscreen gel; Preferably, the sunscreen essence gel contains the following components by mass fraction: 3% active ingredient microcapsules and 97% sunscreen gel.

3. The sunscreen essence gel according to claim 1, characterized in that, The oil phase of the sunscreen gel contains the hydrophilic resin-type silicone elastomer BELSIL® REG 1103 B, which is a compound containing polydimethylsiloxane, a polydimethylsiloxane / vinyltrimethylsiloxane silicate crosspolymer, and octyl polydimethylsiloxane ethoxyglucoside.

4. The sunscreen essence gel according to claim 1, characterized in that, The weight ratio of the oil phase to the water phase in the sunscreen gel is 55-65:45-35; The oil phase components of the sunscreen gel include: 5-12 parts of 1.5cSt polydimethylsiloxane, 2-6 parts of cresoltrazol trisiloxane, 0.5-3 parts of trimethylsiloxysilicate, 0.5-3 parts of isoamyl p-methoxycinnamate, 0.1-0.5 parts of bisabolol, and 10-20 parts of BELSIL® REG 1103 B; The aqueous phase component of the sunscreen gel includes: 4-8 parts of terephthalic acid dicamphor sulfonic acid, 5-8 parts of phenylbenzimidazole sulfonic acid, 2-8 parts of disodium phenylbenzimidazole tetrasulfonate, 1-5 parts of tromethamine, 1-5 parts of aminomethylpropanol, 2-8 parts of glycerin, and the remainder is water.

5. The sunscreen essence gel according to claim 4, characterized in that, The oil phase also contains 0 to 2 parts of polysiloxane-15.

6. The sunscreen essence gel according to claim 1, characterized in that, The capsule walls of the active ingredient microcapsules contain a hydrogel framework formed by agar and sodium alginate. Preferably, the capsule wall further comprises carmine and mica pearlescent powder.

7. The sunscreen essence gel according to claim 1, characterized in that, The particle size of the active ingredient microcapsules is approximately 1-3 mm; Preferably, the oil phase dispersion system of silymarin in the capsule core uses glycerol stearate as the dispersion carrier; The mass fraction of silymarin in the oil phase dispersion system is 1-5%.

8. A method for preparing the sunscreen essence gel according to any one of claims 1 to 7, characterized in that, Includes the following steps: S1 Preparation of oil phase: Mix and disperse the oil phase components evenly at room temperature to obtain the oil phase; S2 Preparation of aqueous phase: Mix and disperse the components of the aqueous phase evenly to obtain the aqueous phase; S3 Preparation of sunscreen gel: After confirming that both the oil phase and the water phase are transparent and the difference in their refractive indices is ≤0.005, the water phase is slowly added to the oil phase while stirring at 50~80 rpm and stirred evenly to obtain the sunscreen gel. S4 Preparation of active ingredient microcapsules: Core-shell hydrogel microcapsules encapsulating silymarin were prepared by concentric sandwich drop method; S5 Product Preparation: Add the active ingredient microcapsules to the sunscreen gel and mix well to obtain the product.

9. The preparation method according to claim 8, characterized in that, The S4 step specifically includes: Agar and sodium alginate were added to an ethanol-water solution and stirred at a constant temperature of 70-80℃ for 0.5-1h to obtain the capsule wall fluid; Glyceryl stearate and silymarin are mixed and heated to 70-80℃ and stirred until homogenized. The mixture is then homogenized at 40-50MPa pressure for 3-5 minutes to obtain the core fluid. A double-layer concentric sandwich dropper is used to allow the capsule wall liquid to flow out simultaneously from the outer annular channel and the capsule core liquid from the inner central channel, forming a sandwich liquid column. After being cut into droplets, the liquid is cooled and solidified to obtain active ingredient microcapsules.

10. The preparation method according to claim 9, characterized in that, Add 18-24 parts of agar, 6-10 parts of sodium alginate, 0.4-0.8 parts of carmine, and 0.4-0.8 parts of mica pearl powder to a 50% ethanol aqueous solution, and stir at a constant temperature of 70-80℃ for 0.5h to obtain the capsule wall liquid; Mix 6-9 parts of glyceryl stearate and 1-5 parts of silymarin, heat to 70°C and stir until homogeneous. Homogenize at 45 MPa for 3 minutes to obtain the core solution.

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