Method for coating mica with titanium dioxide

Abstract

Provided is a method for coating mica with titanium dioxide, comprising: adding 60-70 parts by weight of mica to 1000-1200 parts by weight of water, stirring the mixture to form a suspension, and then adding 30-40 parts by weight of titanium dioxide to the suspension and stirring the mixture to give a mixed suspension; dropwise adding a dilute hydrochloric acid solution to the mixed suspension, and adjusting the pH of the mixed suspension to 2-2.5; raising the temperature of the mixed suspension to 45-80 °C, and carrying out reflux reaction for 2 h; after the reaction is completed, cooling the mixed suspension to room temperature, and filtering and washing the mixed suspension until the pH is 5-7; and after washing, drying the product in an oven to give the mica coated with titanium dioxide on the surface. The product can be used in sunscreen skin care products for children, and has the advantages of good sun protection effect, mildness, and safety.

Description

A method for coating titanium dioxide onto mica Technical Field

[0001] This application relates to the field of sunscreen skincare products, and more specifically, it relates to a method for coating titanium dioxide onto mica. Background Technology

[0002] The sun emits ultraviolet radiation, including UVA, UVB, and UVC. Most UVC is absorbed by the ozone layer, so the majority of UVA and UVB reach the Earth's surface. UVB can cause sunburn, resulting in symptoms such as erythema and blisters; UVA causes skin tanning and aging, and long-term exposure may increase the risk of skin cancer. Therefore, people typically use sunscreen to protect their skin from UV damage.

[0003] Early sunscreens primarily used physical sunscreens, applying simple mineral powders such as zinc oxide to the skin. However, these products had a rough texture, poor user experience, and limited sun protection. Modern sunscreens place greater emphasis on comprehensive performance, requiring not only high-efficiency sun protection but also safety, stability, and comfort. Children's skin is thinner and more delicate than adults', with an underdeveloped stratum corneum and a relatively weaker skin barrier. This makes children's skin less resistant to ultraviolet (UV) radiation and more susceptible to UV damage. Therefore, sunscreens for children should prioritize safety and gentleness while ensuring effective sun protection.

[0004] Many sunscreens currently use nanomaterials, but because nanoparticles are extremely small, typically less than 100 nm, and children's skin is thinner and more delicate than adults', with an underdeveloped stratum corneum and a relatively weaker skin barrier function, these nanoparticles could potentially penetrate the skin barrier and enter the body. Long-term use by children poses a safety risk. Summary of the Invention

[0005] To address the aforementioned problems, this application provides a method for coating titanium dioxide onto mica.

[0006] This application provides a method for coating titanium dioxide onto mica, which employs the following technical solution:

[0007] A method for coating titanium dioxide onto mica includes the following steps:

[0008] Add 60-70 parts by weight of mica to 1000-1200 parts by weight of water, stir to form a suspension, then add 30-40 parts by weight of titanium dioxide to the suspension and stir to obtain a mixture.

[0009] Add dilute hydrochloric acid solution dropwise to the mixture to adjust the pH to 2-2.5; raise the temperature of the mixture to 45-80℃ and reflux for 2 hours.

[0010] After the reaction is complete, cool the mixture to room temperature and filter and wash until the pH is 5-7;

[0011] The washed product was placed in an oven to dry, resulting in mica with a surface coating of titanium dioxide.

[0012] Traditional sunscreens, which heavily utilize nanomaterials, pose a safety hazard as nanoparticles may penetrate children's skin barrier and enter the body. This application's solution, by coating titanium dioxide onto mica, produces relatively large particles, eliminating the potential risks associated with nanoparticles and making it particularly suitable for children. The mica itself is stable and gentle on children's delicate skin. Furthermore, strict control of reaction conditions and washing steps during preparation ensures the final product's pH is within a range suitable for children's skin, minimizing irritation. Adjusting the pH of the mixture to 2-2.5 by adding dilute hydrochloric acid and refluxing at 45-80℃ for 2 hours guarantees uniform coating of titanium dioxide on the mica surface, improving product quality and performance. Titanium dioxide possesses excellent UV reflection and scattering capabilities; coating it onto mica fully utilizes its sun protection properties, providing effective UV protection for children.

[0013] Optionally, the following steps may also be included:

[0014] Add 60-70 parts by weight of mica to 1000-1200 parts by weight of water and stir to form a suspension. Add 20-30 parts by weight of sodium alginate to the suspension and stir for 10-15 minutes. Then add 30-40 parts by weight of titanium dioxide to the suspension and stir to obtain a mixture.

[0015] Add dilute hydrochloric acid solution dropwise to the mixture to adjust the pH to 2-2.5; raise the temperature of the mixture to 45-80℃ and reflux for 2 hours.

[0016] After the reaction is complete, cool the mixture to room temperature and filter and wash until the pH is 5-7;

[0017] The washed product was placed in an oven to dry, resulting in mica with a surface coating of titanium dioxide.

[0018] By employing the above technical solution, mica is made into a suspension, which is then uniformly dispersed in water. Upon addition of sodium alginate, sodium alginate molecules adsorb onto the mica surface. Sodium alginate is a polysaccharide rich in functional groups (such as carboxyl and hydroxyl groups), which can bind to the mica surface through interactions such as hydrogen bonds. When titanium dioxide is subsequently added, sodium alginate acts as a bridge between the mica and titanium dioxide. It guides the titanium dioxide to distribute more evenly on the mica surface, resulting in a more uniform coating of titanium dioxide. Compared to methods without sodium alginate, this avoids potential localized agglomeration of titanium dioxide, thereby improving the consistency of product quality and performance. After pH adjustment and reflux reaction, the presence of sodium alginate can, to some extent, prevent the coated titanium dioxide from detaching. This is like adding an "adhesive" between the coating layer and the mica, making the coating structure more robust and improving the stability of the product during actual use. Furthermore, sodium alginate can adjust the rheological properties of the mixture, making the entire reaction system more stable. During stirring, it can prevent the rapid sedimentation of particles and maintain the good dispersion of particles in the solution.

[0019] Optionally, the mica includes one of sericite, muscovite, and synthetic fluorophlogopite.

[0020] By employing the above-mentioned technical solutions, sericite possesses a fine, sheet-like structure, which enhances the product's smoothness and skin-adherence. Its layered structure forms a strong physical barrier, enhancing the reflection and scattering of ultraviolet rays. Sericite exhibits high chemical stability, is unlikely to react chemically with other components, ensuring product stability during storage and use. Furthermore, it is less irritating to the skin, making it suitable for children's sensitive skin. Muscovite's excellent insulating properties reduce the impact of external factors on sunscreen ingredients, ensuring the sun protection effect of titanium dioxide. Synthetic fluorophlogopite has a high refractive index and ultraviolet reflectivity, enhancing sun protection. Simultaneously, the smooth surface of synthetic fluorophlogopite facilitates easy dispersion in the product, improving its uniformity and stability.

[0021] Optionally, the titanium dioxide includes either rutile titanium dioxide or anatase titanium dioxide.

[0022] By adopting the above technical solution, rutile titanium dioxide has a refractive index of approximately 2.71, which is higher than that of anatase titanium dioxide. This allows it to more effectively reflect and scatter ultraviolet rays, providing stronger sun protection for children. It is also less prone to chemical changes under high temperatures and sunlight, maintaining the stability of its sun protection performance. Anatase titanium dioxide typically has higher whiteness than rutile titanium dioxide, resulting in better appearance for sunscreen products. Furthermore, the production process for anatase titanium dioxide is relatively simple and cost-effective.

[0023] Optionally, the titanium dioxide has a particle size of 30-200 nm.

[0024] By employing the above-mentioned technical solution, the smaller particle size results in a larger specific surface area, allowing for sufficient contact with ultraviolet rays and reflecting them back, thus providing excellent sun protection. Under different lighting conditions, it maintains good ultraviolet reflection capabilities and its performance does not degrade with prolonged exposure to sunlight.

[0025] Optionally, the mica undergoes an acidification pretreatment before preparing the suspension, the acidification pretreatment including:

[0026] Mica was added to a 5-20% hydrochloric acid solution at a solid-liquid ratio of 1:3, and the reaction was carried out at 60 degrees Celsius for 1 hour.

[0027] By employing the above technical solution, the mica surface becomes cleaner after acidification pretreatment, reducing surface impurities and helping to improve the uniformity and firmness of titanium dioxide coating on the mica surface. The crystal structure of the mica surface changes under acidic environments and heating conditions. Hydrogen ions in hydrochloric acid can undergo exchange reactions with some metal ions on the mica surface, and may also break the originally relatively stable chemical bonds on the mica surface, exposing more active sites.

[0028] Optionally, the surface of the titanium dioxide-coated mica may also be coated with microencapsulated purslane extract.

[0029] Optionally, the specific steps for coating the surface of the mica with titanium dioxide and microencapsulated purslane extract are as follows:

[0030] Add 50-60 parts by weight of gelatin and 10-30 parts by weight of purslane extract to 100 parts by weight of water, and stir at a constant temperature of 50-60°C to dissolve and obtain solution A. Add 40-50 parts by weight of gum arabic and 1-3 parts by weight of Tween to 100 parts by weight of water, and stir at a constant temperature of 50-60°C to dissolve and obtain solution B. Mix solution A with solution B to form a homogeneous emulsion.

[0031] Add dilute hydrochloric acid solution dropwise to the emulsion to adjust the pH to 4.0-4.5, and continue stirring to carry out the coagulation reaction;

[0032] After the complex coagulation reaction is completed, titanium dioxide-coated mica is added to the emulsion and ultrasonically dispersed. After completion, 5-10 parts of calcium chloride solution with a concentration of 1-3% are added dropwise to the reaction system while stirring is continued during the dropwise addition to obtain microcapsule liquid.

[0033] The microcapsule liquid was separated by centrifugation to obtain microcapsule precipitate, which was then washed and dried.

[0034] By employing the above-mentioned technical solution, purslane extract exhibits significant anti-inflammatory effects, effectively alleviating skin inflammation in children caused by factors such as ultraviolet radiation. Microencapsulating the extract and coating it on the surface of titanium dioxide-coated mica allows for more precise application of the purslane extract to children's skin when using sunscreen products, specifically reducing skin inflammation. Combining the microencapsulated purslane extract with titanium dioxide-coated mica results in a tighter and more stable bond between the two.

[0035] In summary, this application has the following beneficial effects:

[0036] 1. This application aims to address the safety concerns of nanomaterials in traditional children's sunscreens, which may penetrate children's skin barrier. By coating titanium dioxide onto mica to form larger particles, the potential risks of nanoparticles are avoided, making the product suitable for children. Mica is stable and mild. Strict control of reaction conditions and washing steps during preparation ensures a suitable pH level for the product, minimizing skin irritation in children. A 2-hour reflux reaction under specific pH and temperature conditions guarantees uniform titanium dioxide coating, improving product quality and performance. Furthermore, the UV reflection and scattering capabilities of titanium dioxide provide effective UV protection for children.

[0037] 2. Sodium alginate is preferably used in this application. Sodium alginate is a polysaccharide rich in functional groups (such as carboxyl and hydroxyl groups), which can bind to the mica surface through interactions such as hydrogen bonds. When titanium dioxide is subsequently added, sodium alginate acts as a bridge between the mica and the titanium dioxide. It can guide the titanium dioxide to be distributed more evenly on the mica surface, making the coating of titanium dioxide more uniform and firm.

[0038] 3. In this application, a preferred method is to prepare solution A containing gelatin and purslane extract, and solution B containing gum arabic and Tween, respectively. These solutions are then mixed to form an emulsion. Dilute hydrochloric acid is added dropwise to adjust the pH value, initiating a coagulation reaction. After the reaction is complete, titanium dioxide is added to coat mica, followed by ultrasonic dispersion. Calcium chloride solution is then added dropwise, and finally, the mixture is centrifuged, washed, and dried to obtain microcapsule precipitates. This technical solution utilizes the anti-inflammatory properties of purslane extract, which, after microencapsulation, coats the surface of titanium dioxide-coated mica. This allows for more precise application of sunscreen products to the skin when used on children, reducing inflammation caused by UV radiation and ensuring a tighter and more stable bond between the two. Detailed Implementation

[0039] The following detailed description of this application is provided in conjunction with the embodiments. It should be noted that: unless otherwise specified, the conditions in the following embodiments are performed under conventional conditions or conditions recommended by the manufacturer. Unless otherwise specified, the raw materials used in the following embodiments are all from commercially available sources.

[0040] Example

[0041] Example 1

[0042] A method for coating titanium dioxide onto mica:

[0043] 35g of rutile titanium dioxide with a particle size distribution of 30-200nm and 65g of sericite with a particle size of 20μm were mixed in a beaker, and 1100g of deionized water was added. The mixture was stirred at 800r / min for 15min to obtain a mixture.

[0044] Add 5% (w / w) dilute hydrochloric acid solution dropwise to the mixture to adjust the pH to 2-2.5; raise the temperature of the mixture to 60°C by water bath heating and reflux for 2 hours.

[0045] After the reaction is complete, stop heating, cool the mixture to room temperature, filter it through a filter screen, and then wash the filtered product with deionized water until the pH is 5-7.

[0046] The washed product is placed in an oven and dried at 95°C to obtain mica with titanium dioxide coating on its surface.

[0047] Example 2

[0048] A method for coating titanium dioxide onto mica:

[0049] Mix 30g of rutile titanium dioxide with a particle size of 30-200nm and 70g of sericite with a particle size of 20μm in a beaker, add 1100g of deionized water, and stir at 800r / min for 15min to obtain a mixture.

[0050] Add 5% (w / w) dilute hydrochloric acid solution dropwise to the mixture to adjust the pH to 2-2.5; raise the temperature of the mixture to 60°C by water bath heating and reflux for 2 hours.

[0051] After the reaction is complete, stop heating, cool the mixture to room temperature, filter it through a filter screen, and then wash the filtered product with deionized water until the pH is 5-7.

[0052] The washed product is placed in an oven and dried at 95°C to obtain mica with titanium dioxide coating on its surface.

[0053] Example 3

[0054] A method for coating titanium dioxide onto mica:

[0055] 40g of rutile titanium dioxide with a particle size of 30-200nm and 60g of sericite with a particle size of 20μm were mixed in a beaker, and 1100g of deionized water was added. The mixture was stirred at 800r / min for 15min to obtain a mixture.

[0056] Add 5% (w / w) dilute hydrochloric acid solution dropwise to the mixture to adjust the pH to 2-2.5; raise the temperature of the mixture to 60°C by water bath heating and reflux for 2 hours.

[0057] After the reaction is complete, stop heating, cool the mixture to room temperature, filter it through a filter screen, and then wash the filtered product with deionized water until the pH is 5-7.

[0058] The washed product is placed in an oven and dried at 95°C to obtain mica with titanium dioxide coating on its surface.

[0059] Example 4

[0060] 65g of sericite with a particle size of 20 micrometers was placed in a beaker and 1100g of deionized water was added. The mixture was stirred at 800r / min to obtain a suspension. 25g of sodium alginate (purity >98%) was added to the suspension, and the stirring speed was adjusted to 300r / min. The mixture was stirred for 10min. Then, 35g of rutile titanium dioxide with a particle size distribution of 30-200nm was added to the suspension and stirred for 15min to obtain a mixed solution.

[0061] Add 5% (w / w) dilute hydrochloric acid solution dropwise to the mixture to adjust the pH to 2-2.5; raise the temperature of the mixture to 60°C by water bath heating and reflux for 2 hours.

[0062] After the reaction is complete, stop heating, cool the mixture to room temperature, filter it through a filter screen, and then wash the filtered product with deionized water until the pH is 5-7.

[0063] The washed product is placed in an oven and dried at 95°C to obtain mica with titanium dioxide coating on its surface.

[0064] Example 5

[0065] A method for coating titanium dioxide onto mica: the difference from Example 4 is that 20g of sodium alginate is added to the suspension.

[0066] Example 6

[0067] A method for coating titanium dioxide onto mica: the difference from Example 4 is that 30g of sodium alginate is added to the suspension.

[0068] Example 7

[0069] A method for coating titanium dioxide onto mica: the difference from Example 1 is that the titanium dioxide used is anatase titanium dioxide.

[0070] Example 8

[0071] A method for coating titanium dioxide onto mica: the difference from Example 1 is that muscovite is used as the mica.

[0072] Example 9

[0073] A method for coating titanium dioxide onto mica: the difference from Example 1 is that the mica used is synthetic fluorophlogopite.

[0074] Example 10

[0075] A method for coating titanium dioxide onto mica: the difference from Example 1 is that the titanium dioxide particle size is 10-30 nm.

[0076] Example 11

[0077] A method for coating titanium dioxide onto mica: the difference from Example 1 is that the titanium dioxide particle size is 200-300 nm.

[0078] Example 12

[0079] A method for coating titanium dioxide onto mica: The difference from Example 1 is that the mica requires acidification pretreatment before being added to the beaker.

[0080] Mica was added to the mixture at a solid-liquid ratio of 1:3, the reaction temperature was 60 degrees Celsius, and the reaction time was 1 hour.

[0081] Example 13

[0082] A method for coating titanium dioxide onto mica: differing from Example 12 in that the mass concentration of the hydrochloric acid solution is 5%.

[0083] Example 14

[0084] A method for coating titanium dioxide onto mica: differing from Example 12 in that the mass concentration of the hydrochloric acid solution is 20%.

[0085] Example 15

[0086] A method for coating titanium dioxide onto mica: The difference from Example 1 is that the resulting mica with titanium dioxide coating undergoes the following further treatment:

[0087] Add 55g of gelatin and 20g of purslane extract to 100g of deionized water, heat in a water bath at 55℃ and stir to dissolve to obtain solution A. Add 45g of gum arabic and 2g of Tween-10 to 100g of deionized water, heat in a water bath at 55℃ and stir to dissolve to obtain solution B. Mix solution A with solution B to form a homogeneous emulsion.

[0088] A 5% (w / w) dilute hydrochloric acid solution was added dropwise to the emulsion while stirring continuously. The pH was adjusted to 4.0-4.5, and the reaction was continued with stirring for 2 hours to induce a secondary coagulation reaction.

[0089] After the complex coagulation reaction was completed, 100g of the mixture, which differed from that in Example 4, was added to the emulsion and ultrasonically dispersed for 5 minutes at 48kHz. After the dispersion was completed, 8g of 2% calcium chloride solution was added dropwise to the reaction system while stirring was continued during the addition process to obtain microcapsule liquid.

[0090] The microcapsule liquid was separated by centrifugation to obtain microcapsule precipitate, which was then washed and dried.

[0091] Example 16

[0092] A method for coating titanium dioxide onto mica: The difference from Example 16 is that 55g of gelatin and 10g of purslane extract are added to 100g of deionized water, heated in a water bath at 55°C, and dissolved by stirring to obtain solution A.

[0093] Example 17

[0094] A method for coating titanium dioxide onto mica: The difference from Example 16 is that 55g of gelatin and 30g of purslane extract are added to 100g of deionized water, heated in a water bath at 55°C, and dissolved by stirring to obtain solution A.

[0095] Comparative Example

[0096] Comparative Example 1

[0097] A method for coating titanium dioxide onto mica:

[0098] 40g of rutile titanium dioxide with a particle size of 30-200nm and 60g of sericite with a particle size of 20μm were mixed in a beaker, and 1100g of deionized water was added and stirred to obtain a mixture.

[0099] The temperature of the mixture was raised to 60°C by water bath heating and refluxed for 2 hours. After the reaction was completed, heating was stopped, the mixture was cooled to room temperature, filtered through a filter screen, and the filtered product was washed with deionized water until the pH was 5-7.

[0100] The washed product was placed in an oven and dried at 95°C.

[0101] Comparative Example 2

[0102] A method for coating titanium dioxide onto mica: the difference from Example 4 is that 15g of sodium alginate is added to the suspension.

[0103] Comparative Example 3

[0104] A method for coating titanium dioxide onto mica: the difference from Example 4 is that 35g of sodium alginate is added to the suspension.

[0105] Comparative Example 4

[0106] A method for coating titanium dioxide onto mica: The difference from Example 13 is that 55g of gelatin and 5g of purslane extract are added to 100g of deionized water, heated in a water bath at 55°C, and dissolved by stirring to obtain solution A.

[0107] Comparative Example 5

[0108] A method for coating titanium dioxide onto mica: The difference from Example 13 is that 55g of gelatin and 35g of purslane extract are added to 100g of deionized water, heated in a water bath at 55°C, and dissolved by stirring to obtain solution A.

[0109] Performance testing

[0110] Detection methods

[0111] Take 5g of the titanium dioxide-coated mica prepared above, mix it with 10g of glycerin, and apply it to the surface of a glass substrate with a light transmittance >99%. The coating area is the same. Place a UVB lamp on one side of the glass substrate for irradiation, test the ultraviolet intensity on the other side of the glass substrate, calculate the intensity difference, and determine the ultraviolet blocking rate.

[0112] Five g of the titanium dioxide-coated mica prepared above was stained with fluorescence and mixed with 10 g of glycerol as a sample. Three-month-old hairless mice were selected, and 2 g of the sample was applied to the surface of the mice. The sample was applied to the same location every 24 hours for 30 days. After the end of the period, the epidermis of the application site of the mice, including the epidermis, dermis and subcutaneous tissue, was taken to observe whether the titanium dioxide in the titanium dioxide-coated mica penetrated into the dermis or subcutaneous tissue.

[0113] Take 5g of the titanium dioxide-coated mica prepared above and mix it with 10g of glycerin as a sample. Apply it to the same area of ​​the volunteer's arm. The volunteer has no skin disease. Apply 3g each time, once every 24 hours, and repeat five times. Observe whether allergic or inflammatory symptoms appear in the application area. Test the bacteria on the skin surface before application and 24 hours after application to calculate the antibacterial rate.

[0114] Table 1. Statistical Analysis of Experimental Data

[0115] As can be seen from Example 1 and Comparative Example 1, and Table 1, strict control of reaction conditions and washing steps during the preparation process ensures that the pH of the final product is within a range suitable for children's skin, reducing irritation. Adjusting the pH of the mixture to 2-2.5 by adding dilute hydrochloric acid solution and refluxing the mixture at 45-80℃ for 2 hours ensures uniform coating of titanium dioxide on the mica surface, improving product quality and performance.

[0116] Based on Examples 4-6 and Comparative Examples 2-3, and referring to Table 1, it can be seen that in Examples 4-6, 25g, 20g, and 30g of sodium alginate were used respectively in the process of coating titanium dioxide onto mica. Comparative Example 2 used 15g of sodium alginate, and Comparative Example 3 used 35g of sodium alginate. In terms of UV blocking rate, Examples 4-6 generally showed good UV blocking effect, and the data were relatively close, indicating that sodium alginate helps improve the UV blocking capability of the product. Comparing Comparative Examples 2 and 3 with Examples 4-6, when the amount of sodium alginate was too small, it could not fully exert its role in guiding the uniform coating of titanium dioxide on the mica surface, resulting in a slightly lower UV blocking rate. While excessive use did not significantly reduce the UV blocking rate, further increasing the amount would not significantly improve the effect, which is not conducive to cost control. In summary, the amount of sodium alginate used in this application is approximately 20-30g, which is more beneficial for improving the overall performance, including coating effect, UV blocking rate, and antibacterial rate.

[0117] Combining Examples 16-18 and Comparative Examples 4-5 with Table 1, it can be seen that the amount of purslane extract used in Examples 16-18 was 20g, 10g, and 30g, respectively, while Comparative Examples 4 and 5 used 5g and 35g of purslane extract. From the UV blocking rate data, the amount of purslane extract had a relatively limited impact on UV blocking. However, from the perspective of antibacterial rate, Examples 16-18 showed a trend of changing antibacterial rate with increasing purslane extract dosage. In summary, the amount of purslane extract should be controlled within the range of 20-30g to better exert its antibacterial properties while ensuring the product's basic sun protection function.

[0118] As can be seen from Examples 1-3 and Table 1, traditional sunscreens extensively use nanomaterials, posing a safety hazard as nanoparticles may penetrate the skin barrier and enter the body. The solution in this application, by coating titanium dioxide onto mica, forms relatively large particles, eliminating the potential risk of nanoparticle contamination and making it particularly suitable for children. Titanium dioxide possesses excellent UV reflection and scattering capabilities; by coating titanium dioxide onto mica, its sun protection properties can be fully utilized, providing effective UV protection for children.

[0119] Combining Examples 1 and 4-6 with Table 1, it can be seen that Example 1 did not contain sodium alginate, while Examples 4-6 contained different amounts of sodium alginate. Regarding UV blocking rate, the overall UV blocking rate of Examples 4-6 was higher than that of Example 1, indicating that the addition of sodium alginate helps improve the product's UV blocking ability. This is because sodium alginate allows titanium dioxide to be coated more evenly and firmly on the mica surface, better utilizing the UV reflection and scattering effects of titanium dioxide. In terms of antibacterial rate, the antibacterial rate of Examples 4-6 was also higher than that of Example 1, indicating that the addition of sodium alginate has a positive effect on improving the product's antibacterial performance.

[0120] Based on Examples 1 and 7-11 and Table 1, it can be seen that titanium dioxide with a particle size of 30-200nm has the best overall effect. In this application, the mica can be sericite, muscovite, or synthetic fluorophlogopite, and the titanium dioxide can be rutile or anatase, all of which can achieve good UV protection and are safe and non-irritating.

[0121] Combining Examples 1 and 12-14 with Table 1, it can be seen that Example 1 did not undergo acidification pretreatment of mica. From the perspective of UV blocking rate, the overall UV blocking rate of Examples 12-14 is better than that of Example 1, indicating that after acidification pretreatment, the surface of mica is cleaner and the number of surface active sites increases, resulting in a better coating effect of titanium dioxide on the mica, thereby improving the sun protection ability of the product.

[0122] Combining Examples 1 and 15-17 with Table 1, it can be seen that Examples 15-17 underwent microencapsulation-related post-processing and adjusted the dosage of purslane extract. Regarding the UV blocking rate, Examples 15-17 differ somewhat from Example 1, but this difference is not particularly large, indicating that subsequent microencapsulation and other operations do not have a dominant impact on the product's primary sun protection performance (UV blocking), but they do have a certain moderating effect. However, in terms of antibacterial rate, Examples 15-17 show a significantly higher antibacterial rate compared to Example 1, indicating that purslane extract has a significant optimizing effect on the product's antibacterial performance. Through the formation of the microcapsule structure and the synergistic effect between the components, it can effectively inhibit the growth of microorganisms, enhance the product's antibacterial ability, and enable the product to exhibit better application effects in antibacterial aspects while maintaining sun protection functionality.

[0123] This specific embodiment is merely an explanation of this application and is not intended to limit it. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they fall within the scope of the claims of this application.

Claims

1. A method for coating titanium dioxide onto mica, characterized in that, Includes the following steps: Add 60-70 parts by weight of mica to 1000-1200 parts by weight of water, stir to form a suspension, then add 30-40 parts by weight of titanium dioxide to the suspension and stir to obtain a mixture. Add dilute hydrochloric acid solution dropwise to the mixture to adjust the pH to 2-2.5; raise the temperature of the mixture to 45-80℃ and reflux for 2 hours. After the reaction is complete, cool the mixture to room temperature and filter and wash until the pH is 5-7; The washed product was placed in an oven to dry, resulting in mica with a surface coating of titanium dioxide.

2. The method of coating titanium dioxide on mica according to claim 1, characterized in that: It also includes the following steps: Add 60-70 parts by weight of mica to 1000-1200 parts by weight of water and stir to form a suspension. Add 20-30 parts by weight of sodium alginate to the suspension and stir for 10-15 minutes. Then add 30-40 parts by weight of titanium dioxide to the suspension and stir for 10-15 minutes to obtain a mixture. Add dilute hydrochloric acid solution dropwise to the mixture to adjust the pH to 2-2.5; raise the temperature of the mixture to 45-80℃ and reflux for 2 hours. After the reaction is complete, cool the mixture to room temperature and filter and wash until the pH is 5-7; The washed product was placed in an oven to dry, resulting in mica with a surface coating of titanium dioxide.

3. The method for coating titanium dioxide onto mica according to claim 1 or 2, characterized in that: The mica includes one of sericite, muscovite, and synthetic fluorophlogopite.

4. The method for coating titanium dioxide onto mica according to claim 1 or 2, characterized in that: The titanium dioxide includes either rutile titanium dioxide or anatase titanium dioxide.

5. The method for coating titanium dioxide onto mica according to claim 1 or 2, characterized in that: The titanium dioxide has a particle size of 30-200 nm.

6. The method for coating titanium dioxide onto mica according to claim 1 or 2, characterized in that: The mica undergoes an acidification pretreatment before the suspension is prepared. The acidification pretreatment includes: Mica was added to a 5-20% hydrochloric acid solution at a solid-liquid ratio of 1:3, and the reaction was carried out at 60 degrees Celsius for 1 hour.

7. The method for coating titanium dioxide onto mica according to claim 1 or 2, characterized in that: The mica surface, which is coated with titanium dioxide, is also coated with microencapsulated purslane extract.

8. The method for coating titanium dioxide onto mica according to claim 7, characterized in that: The specific steps for the mica-encapsulated microencapsulated purslane extract with titanium dioxide coated on its surface are as follows: Add 50-60 parts by weight of gelatin and 10-30 parts by weight of purslane extract to 100 parts by weight of water, and stir at a constant temperature of 50-60°C to dissolve and obtain solution A. Add 40-50 parts by weight of gum arabic and 1-3 parts by weight of Tween to 100 parts by weight of water, and stir at a constant temperature of 50-60°C to dissolve and obtain solution B. Mix solution A with solution B to form an emulsion. Add dilute hydrochloric acid solution dropwise to the emulsion to adjust the pH to 4.0-4.5, and continue stirring to carry out the coagulation reaction; After the complex coagulation reaction is completed, titanium dioxide-coated mica is added to the emulsion and ultrasonically dispersed. After completion, 5-10 parts of calcium chloride solution with a concentration of 1-3% are added dropwise to the reaction system while stirring is continued during the dropwise addition to obtain microcapsule liquid. The microcapsule liquid was separated by centrifugation to obtain microcapsule precipitate, which was then washed and dried.

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