An ultrafine titanium dioxide powder and a preparation method thereof

Abstract

The present invention provides an ultrafine titanium dioxide powder and a preparation method thereof, belonging to the technical field of titanium dioxide. Tetrabutyl titanate and tetraethyl orthosilicate are added to a surfactant solution for emulsification reaction, and then calcined twice to obtain non-polar nano TiO2 / SiO2 powder and micro-polar nano TiO2 / SiO2 powder. The micro-polar nano TiO2 / SiO2 powder is loaded with graphene quantum dots and stearic acid, and prepared into liposomes, which are mixed evenly with the non-polar nano TiO2 / SiO2 powder to obtain the ultrafine titanium dioxide powder. The ultrafine titanium dioxide powder prepared by the present invention has good dispersibility, and has good skin-friendly, compliant and delicate effects when used in cosmetics. Moreover, it has good antibacterial and anti-inflammatory properties, excellent ultraviolet resistance, and broad application prospects.

Description

Technical Field

[0001] The present invention relates to the technical field of titanium dioxide, and particularly to an ultrafine titanium dioxide powder and a preparation method thereof. Background Art

[0002] Titanium dioxide is one of the important metal oxides and is widely used in industries such as military, rubber, plastics, papermaking, printing ink, chemical fiber, and cosmetics. Due to the small particle size, large specific surface area, and high surface energy of ultrafine TiO2, it is easy to cause agglomeration, especially hard agglomeration, during the drying and calcination processes, which makes the dispersibility of the product poor and affects the use effect and application range of the product. The liquid phase method has more processes, a complicated production process, and a high preparation cost; the gas phase method for producing ultrafine titanium dioxide powder has high requirements for technical level and process parameter control, and the prepared product has good quality but poor performance.

[0003] Chinese invention patent CN113896233B discloses a preparation method of low-temperature crystallized titanium dioxide; Chinese invention patent CN114162860B discloses a preparation method of titanium dioxide porous spheres; Chinese invention patent CN113912109B discloses a preparation method of nano titanium dioxide porous materials; Chinese invention patent CN113957506B discloses a preparation method of rutile-type titanium dioxide plates; Chinese invention patent CN113896234B discloses a preparation method of nano titanium dioxide; Chinese invention patent application CN114906873A discloses a preparation method of anatase-type titanium dioxide. There are various preparation methods of titanium dioxide in the prior art, most of which are based on the process technical process of sulfuric acid process titanium white, that is, using the intermediate product in the production process of sulfuric acid process titanium white as the raw material and using hydrothermal reaction to prepare the corresponding nano titanium dioxide, such as Chinese invention patents CN113896234B, CN113896233B, and CN114162860B; or using other substances to make core-shell structured nano titanium dioxide, such as Chinese invention patent CN113912109B; or based on the basic sulfuric acid process titanium white production process, titanium white can be prepared, such as Chinese invention patent application CN114906873A. Most of the methods for preparing ultrafine titanium dioxide by the above technologies require complex process flows, expensive equipment, or need to use other costly auxiliary materials, and the production cost is relatively high. Therefore, it is urgent to study a new preparation method for ultrafine titanium dioxide. Summary of the Invention

[0004] The purpose of the present invention is to provide an ultrafine titanium dioxide powder and a preparation method thereof, which have good dispersibility, have good skin-friendly, fitting, and delicate effects when used in cosmetics, and have good antibacterial and anti-inflammatory properties and excellent ultraviolet resistance, and have broad application prospects.

[0005] The technical solution of the present invention is realized as follows:

[0006] The present invention provides a method for preparing ultrafine titanium dioxide powder, comprising the following steps:

[0007] S1. Preparation of precursor: A mixed solution of tetrabutyl titanate and tetraethyl orthosilicate is dropped into a surfactant solution, the pH value of the solution is adjusted, emulsified, heated and stirred for reaction, centrifuged, washed, and dried to obtain a precursor;

[0008] S2. Calcination: The precursor is heated to a first temperature for calcination to obtain non-polar nano TiO2 / SiO2 powder; the precursor is heated to a second temperature for calcination to obtain micro-polar nano TiO2 / SiO2 powder;

[0009] S3. Preparation of graphene quantum dot-doped nano TiO2 / SiO2 powder: The micro-polar nano TiO2 / SiO2 powder is added to a citric acid solution, subjected to hydrothermal reaction, centrifuged, washed, and dried to obtain graphene quantum dot-doped nano TiO2 / SiO2 powder;

[0010] S4. Coating with stearic acid: The graphene quantum dot-doped nano TiO2 / SiO2 powder is mixed with stearic acid and ball-milled to obtain coated graphene quantum dot-doped nano TiO2 / SiO2 powder;

[0011] S5. Preparation of liposome: Lecithin, phosphorylcholine polymer and cholesterol are dissolved in an organic solvent, the coated graphene quantum dot-doped nano TiO2 / SiO2 is added, stirred, the organic solvent is removed under reduced pressure, water is added, ultrasonic treatment is carried out, and freeze-drying is carried out to obtain liposome;

[0012] S6. Preparation of ultrafine titanium dioxide powder: The liposome and non-polar nano TiO2 / SiO2 powder are mixed evenly to obtain ultrafine titanium dioxide powder.

[0013] As a further improvement of the present invention, in step S1, the mass ratio of tetrabutyl titanate, tetraethyl orthosilicate and surfactant is 10-15:5-8:1-2, the pH value of the adjusted solution is 10-11, the emulsification condition is 8000-10000 r / min, the time is 10-15 min, the temperature of the heating and stirring reaction is 50-60 °C, the time is 1-3 h, and the surfactant is selected from at least one of Tween-20, Tween-40, Tween-60, and Tween-80.

[0014] As a further improvement of the present invention, in step S2, the temperature of the first temperature calcination is 800-900 °C, the time is 2-4 h; the temperature of the second temperature calcination is 400-500 °C, the time is 2-4 h.

[0015] As a further improvement of the present invention, in step S3, the mass ratio of the micro-polar nano-TiO2 / SiO2 powder to citric acid is 100:15 - 22, the temperature of the hydrothermal reaction is 200 - 220 °C, and the time is 15 - 20 min.

[0016] As a further improvement of the present invention, in step S4, the mass ratio of the graphene quantum dot-doped nano-TiO2 / SiO2 powder to stearic acid is 10:1 - 2, and the ball milling time is 0.5 - 1.5 h.

[0017] As a further improvement of the present invention, in step S5, the mass ratio of lecithin, phosphorylcholine polymer, cholesterol, and graphene quantum dot-doped nano-TiO2 / SiO2 is 20 - 40:18 - 35:7 - 10:8 - 10, the stirring time is 20 - 30 min, the power of the ultrasonic treatment is 1000 - 1500 W, and the time is 10 - 15 min; the phosphorylcholine polymer is selected from at least one of polyquaternium-51, polyquaternium-61, polyquaternium-64, and polyquaternium-65, that is, at least one of homopolymer of 2-methacryloyloxyethyl phosphorylcholine, 2-methacryloyloxyethyl phosphorylcholine, poly(phosphorylcholine) ethylene glycol acrylate, and poly(phosphorylcholine) n-butyl methacrylate.

[0018] As a further improvement of the present invention, in step S6, the mass ratio of the liposome to the non-polar nano-TiO2 / SiO2 powder is 80 - 90:5 - 10.

[0019] The present invention further protects an ultrafine titanium dioxide powder prepared by the above preparation method.

[0020] The present invention further protects the application of the above ultrafine titanium dioxide powder in the fields of cosmetics or coatings.

[0021] The present invention has the following beneficial effects:

[0022] Due to the large specific surface area and more surface empty bonds of nano TiO2, it is very easy to agglomerate during the preparation and application process, so that its excellent performance cannot be fully exerted. The present invention mixes tetraethyl orthosilicate and tetrabutyl titanate and adds them into a surfactant solution, forms tiny nano-scale water-in-oil droplets through emulsification, and rapidly catalyzes a sol-gel reaction to obtain a nano-scale precursor, and calcines at different temperature sections to obtain a non-polar nano TiO2 / SiO2 powder containing rutile titanium dioxide at 700-800°C, wherein the rutile titanium dioxide belongs to the tetragonal system, is relatively dense and stable, and has a symmetrical structure so that it has no polarity. The micro-polar nano TiO2 / SiO2 powder containing anatase-type titanium dioxide obtained by calcination at 400-500°C, wherein the octahedron of anatase-type TiO2 is obviously orthorhombic and distorted, and the distance of Ti-O bonds is very small and unequal. This imbalance makes the TiO2 molecule very polar, and makes the TiO2 surface easy to adsorb water molecules and polarize the water molecules to form surface hydroxyl groups, which can better complete the subsequent surface modification. In addition, the surface of the obtained nano TiO2 / SiO2 powder has a silicon oxygen layer, and silicon is precipitated on the surface of titanium dioxide particles in the form of Si(OH)4. Monomolecular orthosilicic acid polymerizes at different rates, and begins to precipitate out monomeric orthosilicic acid or low-polymerization silicate polymers. The highly active active silicon is firmly bonded to the surface hydroxyl groups of titanium dioxide, forming nucleation points on the surface of titanium dioxide. At these nucleation points, it can quickly react with TiO2 to form Ti-O-Si bonds, generating titanium oxide and silicon oxide composite nanoparticles. The addition of SiO2 makes the surface of the prepared nano-TiO2 / SiO2 powder have negative charges, making its nanostructure less likely to agglomerate.

[0023] In natural sunlight, UVA accounts for 90%-95% of the total ultraviolet rays reaching the earth's surface, while UVB accounts for only 5%-10%. This means that the intensity of UVA is much higher than that of UVB. Titanium dioxide has different blocking mechanisms for ultraviolet rays of different wavelengths. Titanium dioxide with a particle size greater than 0.1μm has a stronger light scattering property and mainly blocks UVA; titanium dioxide with a particle size less than 0.1μm has a smaller particle size and relatively weaker light scattering, and its sun protection property is mainly to absorb UVB.

[0024] The non-polar nano TiO2 / SiO2 powder (with a particle size of less than 0.1 μm) prepared by the present invention has a good absorption effect on UVB, while the micro-polar nano TiO2 / SiO2 powder has a smaller particle size and needs further modification.

[0025] The prepared micro-polar nano-TiO2 / SiO2 powder of the present invention has hydroxyl groups on its surface, which can adsorb citric acid, and graphene quantum dots are in-situ generated on the surface. On the one hand, it increases the size of the nanoparticles, and on the other hand, it realizes lattice change, so that TiO2 can utilize the visible light region, enhancing its photocatalytic antibacterial and chemical stability, and improving the anti-inflammatory effect.

[0026] Further, after the prepared nano-TiO2 / SiO2 powder doped with graphene quantum dots is coated and modified with stearic acid, Ti 4+ forms a bidentate complex with carboxylic acid and can exist uniformly and stably in the organic phase, thereby improving its dispersibility and further avoiding its agglomeration.

[0027] The prepared nano-TiO2 / SiO2 powder coated with doped graphene quantum dots of the present invention is formed into liposomes by coating with lecithin and cholesterol, improving the water dispersibility of the material and further improving the dispersion performance of the material, making the material have good hydrophilicity, and having a more skin-friendly, more fitting and delicate effect when used as a cosmetic material.

[0028] The prepared ultrafine titanium dioxide powder of the present invention has good dispersibility, has a good skin-friendly, fitting and delicate effect when used in cosmetics, and has good antibacterial and anti-inflammatory properties and excellent ultraviolet resistance, and has broad application prospects. Specific embodiments

[0029] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0030] Example 1: This example provides a preparation method of ultrafine titanium dioxide powder, including the following steps:

[0031] S1. Preparation of the precursor: A dichloromethane solution containing 10 g of tetrabutyl titanate and 5 g of tetraethyl orthosilicate in 200 mL is dropped into an aqueous solution containing 1 g of Tween-20 in 500 mL, the pH value of the solution is adjusted to 10, emulsified at 8000 r / min for 15 min, heated to 60 °C, stirred and reacted for 1 h, centrifuged, washed, and dried to obtain the precursor;

[0032] S2. Calcination: The precursor is heated to 850 °C and calcined for 2 h to obtain non-polar nano-TiO2 / SiO2 powder; the precursor is heated to 400 °C and calcined for 2 h to obtain micro-polar nano-TiO2 / SiO2 powder;

[0033] S3. Preparation of graphene quantum dot-doped nano-TiO₂ / SiO₂ powder: Add 10 g of micro-polar nano-TiO₂ / SiO₂ powder into 200 mL of an aqueous solution containing 1.5 g of citric acid, perform hydrothermal reaction at 200 °C for 15 min, centrifuge, wash, and dry to obtain graphene quantum dot-doped nano-TiO₂ / SiO₂ powder;

[0034] S4. Coating with stearic acid: Mix 10 g of graphene quantum dot-doped nano-TiO₂ / SiO₂ powder with 1 g of stearic acid, ball mill for 0.5 h to obtain coated graphene quantum dot-doped nano-TiO₂ / SiO₂ powder;

[0035] S5. Preparation of liposomes: Dissolve 20 g of lecithin, 7 g of 2-methacryloyloxyethyl phosphorylcholine homopolymer, and 18 g of cholesterol in 500 mL of a mixed solution of dichloromethane and ethanol (volume ratio of dichloromethane to ethanol is 1:1), add 8 g of coated graphene quantum dot-doped nano-TiO₂ / SiO₂, stir for 20 min, remove the organic solvent by rotary evaporation under reduced pressure, add 200 mL of water, perform ultrasonic treatment at 1000 W for 10 min, and freeze-dry to obtain liposomes;

[0036] S6. Preparation of ultrafine titanium dioxide powder: Stir and mix 8 g of liposomes and 0.5 g of non-polar nano-TiO₂ / SiO₂ powder for 10 min to obtain ultrafine titanium dioxide powder.

[0037] Example 2: This example provides a method for preparing ultrafine titanium dioxide powder, including the following steps:

[0038] S1. Preparation of the precursor: Drop 200 mL of a dichloromethane solution containing 15 g of tetrabutyl titanate and 8 g of tetraethyl orthosilicate into 500 mL of an aqueous solution containing 2 g of Tween-40, adjust the pH value of the solution to 11, emulsify at 10000 r / min for 15 min, heat to 50 °C, stir and react for 3 h, centrifuge, wash, and dry to obtain the precursor;

[0039] S2. Calcination: Heat the precursor to 900 °C and calcine for 4 h to obtain non-polar nano-TiO₂ / SiO₂ powder; heat the precursor to 500 °C and calcine for 4 h to obtain micro-polar nano-TiO₂ / SiO₂ powder;

[0040] S3. Preparation of graphene quantum dot-doped nano-TiO₂ / SiO₂ powder: Add 10 g of micro-polar nano-TiO₂ / SiO₂ powder into 200 mL of an aqueous solution containing 2.2 g of citric acid, perform hydrothermal reaction at 220 °C for 20 min, centrifuge, wash, and dry to obtain graphene quantum dot-doped nano-TiO₂ / SiO₂ powder;

[0041] S4. Coating with stearic acid: 10 g of graphene quantum dot-doped nano-TiO2 / SiO2 powder is mixed with 2 g of stearic acid and ball-milled for 1.5 h to obtain graphene quantum dot-doped nano-TiO2 / SiO2 powder with a coating;

[0042] S5. Preparation of liposomes: 40 g of lecithin, 10 g of 2-methacryloyloxyethyl phosphorylcholine, and 35 g of cholesterol are dissolved in 500 mL of a mixed solution of dichloromethane and ethanol (the volume ratio of dichloromethane to ethanol is 1:1). 10 g of graphene quantum dot-doped nano-TiO2 / SiO2 with a coating is added, and the mixture is stirred for 30 min. The organic solvent is removed by rotary evaporation under reduced pressure. 200 mL of water is added, and the mixture is ultrasonically treated at 1500 W for 15 min and then freeze-dried to obtain liposomes;

[0043] S6. Preparation of ultrafine titanium dioxide powder: 9 g of liposomes and 1 g of non-polar nano-TiO2 / SiO2 powder are stirred and mixed for 10 min to obtain ultrafine titanium dioxide powder.

[0044] Example 3: This example provides a method for preparing ultrafine titanium dioxide powder, which includes the following steps:

[0045] S1. Preparation of the precursor: 200 mL of a dichloromethane solution containing 12 g of tetrabutyl titanate and 6 g of tetraethyl orthosilicate is dropped into 500 mL of an aqueous solution containing 1.5 g of Tween-80. The pH value of the solution is adjusted to 10.5, and the mixture is emulsified at 9000 r / min for 12 min, heated to 5 °C, stirred and reacted for 2 h, centrifuged, washed, and dried to obtain the precursor;

[0046] S2. Calcination: The precursor is heated to 870 °C and calcined for 3 h to obtain non-polar nano-TiO2 / SiO2 powder; the precursor is heated to 450 °C and calcined for 3 h to obtain micro-polar nano-TiO2 / SiO2 powder;

[0047] S3. Preparation of graphene quantum dot-doped nano-TiO2 / SiO2 powder: 10 g of micro-polar nano-TiO2 / SiO2 powder is added to 200 mL of an aqueous solution containing 2 g of citric acid, and hydrothermally reacted at 210 °C for 17 min, centrifuged, washed, and dried to obtain graphene quantum dot-doped nano-TiO2 / SiO2 powder;

[0048] S4. Coating with stearic acid: 10 g of graphene quantum dot-doped nano-TiO2 / SiO2 powder is mixed with 1.5 g of stearic acid and ball-milled for 1 h to obtain graphene quantum dot-doped nano-TiO2 / SiO2 powder with a coating;

[0049] S5. Preparation of liposomes: Dissolve 30 g of lecithin, 8.5 g of 2-methacryloyloxyethyl phosphorylcholine, and 25 g of cholesterol in 500 mL of a mixed solution of dichloromethane and ethanol (the volume ratio of dichloromethane to ethanol is 1:1). Add 9 g of nanometer TiO2 / SiO2 doped with graphene quantum dots, stir for 25 min, remove the organic solvent by rotary evaporation under reduced pressure, add 200 mL of water, perform ultrasonic treatment at 1200 W for 12 min, and then freeze-dry to obtain liposomes;

[0050] S6. Preparation of ultrafine titanium dioxide powder: Stir and mix 8.5 g of liposomes and 0.7 g of non-polar nanometer TiO2 / SiO2 powder for 10 min to obtain ultrafine titanium dioxide powder.

[0051] Comparative Example 1

[0052] Compared with Example 3, the difference lies in that tetraethyl orthosilicate was not added in step S1.

[0053] Specifically as follows:

[0054] S1. Preparation of precursor: Drop 200 mL of a dichloromethane solution containing 18 g of tetrabutyl titanate into 500 mL of an aqueous solution containing 1.5 g of Tween-80, adjust the pH value of the solution to 10.5, emulsify at 9000 r / min for 12 min, heat to 5 °C, stir and react for 2 h, centrifuge, wash, and dry to obtain the precursor.

[0055] Comparative Example 2

[0056] Compared with Example 3, the difference lies in that step S3 was not carried out.

[0057] Specifically as follows:

[0058] S1. Preparation of precursor: Drop 200 mL of a dichloromethane solution containing 12 g of tetrabutyl titanate and 6 g of tetraethyl orthosilicate into 500 mL of an aqueous solution containing 1.5 g of Tween-80, adjust the pH value of the solution to 10.5, emulsify at 9000 r / min for 12 min, heat to 5 °C, stir and react for 2 h, centrifuge, wash, and dry to obtain the precursor;

[0059] S2. Calcination: Heat the precursor to 870 °C and calcine for 3 h to obtain non-polar nanometer TiO2 / SiO2 powder; heat the precursor to 450 °C and calcine for 3 h to obtain micro-polar nanometer TiO2 / SiO2 powder;

[0060] S3. Coating with stearic acid: Mix 10 g of nanometer TiO2 / SiO2 powder doped with graphene quantum dots with 1.5 g of stearic acid, and ball mill for 1 h to obtain nanometer TiO2 / SiO2 powder doped with graphene quantum dots coated with stearic acid;

[0061] S4. Preparation of liposomes: Dissolve 30 g of lecithin, 8.5 g of 2-methacryloyloxyethyl phosphorylcholine, and 25 g of cholesterol in 500 mL of a mixed solution of dichloromethane and ethanol (the volume ratio of dichloromethane to ethanol is 1:1). Add 9 g of graphene quantum dot-doped nano-TiO2 / SiO2, stir for 25 min, remove the organic solvent by rotary evaporation under reduced pressure, add 200 mL of water, sonicate at 1200 W for 12 min, and freeze-dry to obtain liposomes;

[0062] S5. Preparation of ultrafine titanium dioxide powder: Stir and mix 8.5 g of liposomes and 0.7 g of non-polar nano-TiO2 / SiO2 powder for 10 min to obtain ultrafine titanium dioxide powder.

[0063] Comparative Example 3

[0064] Compared with Example 3, the difference is that step S4 is not carried out.

[0065] Specifically as follows:

[0066] S1. Preparation of precursor: Drop 200 mL of a dichloromethane solution containing 12 g of tetrabutyl titanate and 6 g of tetraethyl orthosilicate into 500 mL of an aqueous solution containing 1.5 g of Tween-80, adjust the pH value of the solution to 10.5, emulsify at 9000 r / min for 12 min, heat to 5 °C, stir and react for 2 h, centrifuge, wash, and dry to obtain the precursor;

[0067] S2. Calcination: Heat the precursor to 870 °C and calcine for 3 h to obtain non-polar nano-TiO2 / SiO2 powder; heat the precursor to 450 °C and calcine for 3 h to obtain micro-polar nano-TiO2 / SiO2 powder;

[0068] S3. Preparation of graphene quantum dot-doped nano-TiO2 / SiO2 powder: Add 10 g of micro-polar nano-TiO2 / SiO2 powder to 200 mL of an aqueous solution containing 2 g of citric acid, carry out hydrothermal reaction at 210 °C for 17 min, centrifuge, wash, and dry to obtain graphene quantum dot-doped nano-TiO2 / SiO2 powder;

[0069] S4. Preparation of liposomes: Dissolve 30 g of lecithin, 8.5 g of 2-methacryloyloxyethyl phosphorylcholine, and 25 g of cholesterol in 500 mL of a mixed solution of dichloromethane and ethanol (the volume ratio of dichloromethane to ethanol is 1:1). Add 9 g of graphene quantum dot-doped nano-TiO2 / SiO2, stir for 25 min, remove the organic solvent by rotary evaporation under reduced pressure, add 200 mL of water, sonicate at 1200 W for 12 min, and freeze-dry to obtain liposomes;

[0070] S5. Preparation of ultrafine titanium dioxide powder: 8.5 g of liposomes and 0.7 g of non-polar nano TiO2 / SiO2 powder were stirred and mixed for 10 min to obtain ultrafine titanium dioxide powder.

[0071] Comparative Example 4

[0072] Compared with Example 3, the difference lies in that step S5 was not carried out.

[0073] Specifically as follows:

[0074] S1. Preparation of precursor: A dichloromethane solution containing 12 g of tetrabutyl titanate and 6 g of tetraethyl orthosilicate in 200 mL was dropped into an aqueous solution containing 1.5 g of Tween-80 in 500 mL. The pH value of the solution was adjusted to 10.5, emulsified at 9000 r / min for 12 min, heated to 5 °C, stirred and reacted for 2 h, centrifuged, washed, and dried to obtain the precursor;

[0075] S2. Calcination: The precursor was heated to 870 °C and calcined for 3 h to obtain non-polar nano TiO2 / SiO2 powder; the precursor was heated to 450 °C and calcined for 3 h to obtain micro-polar nano TiO2 / SiO2 powder;

[0076] S3. Preparation of graphene quantum dot-doped nano TiO2 / SiO2 powder: 10 g of micro-polar nano TiO2 / SiO2 powder was added to an aqueous solution containing 2 g of citric acid in 200 mL, and hydrothermally reacted at 210 °C for 17 min, centrifuged, washed, and dried to obtain graphene quantum dot-doped nano TiO2 / SiO2 powder;

[0077] S4. Coating with stearic acid: 10 g of graphene quantum dot-doped nano TiO2 / SiO2 powder was mixed with 1.5 g of stearic acid and ball-milled for 1 h to obtain stearic acid-coated graphene quantum dot-doped nano TiO2 / SiO2 powder;

[0078] S5. Preparation of ultrafine titanium dioxide powder: 8.5 g of stearic acid-coated graphene quantum dot-doped nano TiO2 / SiO2 powder and 0.7 g of non-polar nano TiO2 / SiO2 powder were stirred and mixed for 10 min to obtain ultrafine titanium dioxide powder.

[0079] Comparative Example 5

[0080] Compared with Example 3, the difference lies in that the mass ratio of liposomes to non-polar nano TiO2 / SiO2 powder in step S6 is 0.7:8.5.

[0081] Comparative Example 6

[0082] Compared with Example 3, the difference lies in that non-polar nano TiO2 / SiO2 powder was not added in step S6.

[0083] Comparative Example 7

[0084] Compared with Example 3, the difference lies in that no liposome was added in step S6.

[0085] Test Example 1 Detection of Photosensitivity Color Difference

[0086] The products prepared in Examples 1-3 or Comparative Examples 1-7 were mixed evenly with 1,3-butanediol at a mass ratio of 1:1. The material was coated on a glass slide with a thickness of 0.5 mm, covered with a cover glass, and immediately the L ∗ , a ∗ , b ∗ value was measured using a colorimeter (CM508D, Minolta, Japan). The D25 light source was adopted, the angle was 10°, and the operation was carried out avoiding sunlight. After the above sample plate was taken out after being irradiated in an aging instrument (CI3000, TLAS, USA) for 30 min, the L ∗ , a ∗ , b ∗ value after illumination was measured immediately, and the color difference ΔE of the sample before and after illumination was calculated by the following formula. The results are shown in Table 1.

[0087] ΔE =

(L ∗ 后 - L ∗ 前 )2 + (a ∗ 后 - a ∗ 前 )2 + (b ∗ 后 - b ∗ 前 )

[0088] Table 1

[0089]

[0090] As can be seen from the above table, the ΔE of the ultrafine titanium dioxide powder prepared in Examples 1-3 of the present invention is lower, the photoactivity is low, and the performance is more stable.

[0091] Test Example 2 Detection of SPF Value

[0092] The products prepared in Examples 1-3 or Comparative Examples 1-7 were fully mixed evenly with sericite in a powder mixer at a ratio of 1:10. The sample was coated on the tape at a rate of 0.75 mg / cm 2 for standby. During measurement, a blank test was first carried out with the tape. A SPF290 detector was used to quantitatively analyze the sun protection effect of the sample. The monochromatic light protection factor MPF λThe blocking ability of the sample to monochromatic light with a wavelength of λ, the magnitude of which is the transmittance T of the light of this wavelength λ is the reciprocal, that is, MPF λ = 1 / T λ . The results are shown in Table 2

[0093] Define the comprehensive sun protection factor SPF value in the UVA and UVB ranges as follows:

[0094] ;

[0095] wherein, E λ is the light factor, B λ is the erythema factor, respectively representing the ultraviolet intensity at the wavelength λ and the degree of erythema that may be caused to the skin

[0096] Table 2

[0097]

[0098] As can be seen from the above table, the ultrafine titanium dioxide powder prepared in Examples 1-3 of the present invention has a high SPF value and has a good anti-ultraviolet radiation effect

[0099] Test Example 3

[0100] The products prepared in Examples 1-3 or Comparative Examples 1-7 were formulated into a 10 wt% aqueous dispersion, 1 wt% of the dispersant sodium silicate was added, and the ζ potential was measured using a ZETAPLUS potentiometer. The results are shown in Table 3

[0101] Table 3

[0102]

[0103] As can be seen from the above table, the ζ potential of the ultrafine titanium dioxide powder prepared in Examples 1-3 of the present invention in water is negative, and the dispersibility is good

[0104] Test Example 4

[0105] The specific surface area of the products prepared in Examples 1-3 or Comparative Examples 1-7 was measured using a 3-FLEX 3500 multi-station high-throughput gas adsorption instrument. The results are shown in Table 4

[0106] Table 4

[0107]

[0108] As can be seen from the above table, the ultrafine titanium dioxide powder prepared in Examples 1-3 of the present invention has a large specific surface area

[0109] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims

1. A method for preparing ultrafine titanium dioxide powder, characterized in that, It includes the following steps: S1. Preparation of the precursor: Drop the mixed solution of tetrabutyl titanate and tetraethyl orthosilicate into the surfactant solution, adjust the pH value of the solution, emulsify, heat and stir for reaction, centrifuge, wash, and dry to obtain the precursor; S2. Calcination: Heat the precursor to the first temperature for calcination to obtain non-polar nano TiO2 / SiO2 powder; heat the precursor to the second temperature for calcination to obtain micro-polar nano TiO2 / SiO2 powder; the temperature of the first temperature calcination is 800 - 900 °C, and the time is 2 - 4 h; the temperature of the second temperature calcination is 400 - 500 °C, and the time is 2 - 4 h; S3. Preparation of graphene quantum dot-doped nano TiO2 / SiO2 powder: Add the micro-polar nano TiO2 / SiO2 powder to the citric acid solution, carry out hydrothermal reaction, centrifuge, wash, and dry to obtain graphene quantum dot-doped nano TiO2 / SiO2 powder; S4. Coating with stearic acid: Mix the graphene quantum dot-doped nano TiO2 / SiO2 powder with stearic acid and ball mill to obtain coated graphene quantum dot-doped nano TiO2 / SiO2 powder; S5. Preparation of liposomes: Dissolve lecithin, phosphorylcholine polymer, and cholesterol in an organic solvent, add the coated graphene quantum dot-doped nano TiO2 / SiO2, stir, remove the organic solvent under reduced pressure, add water, carry out ultrasonic treatment, and freeze-dry to obtain liposomes; S6. Preparation of ultrafine titanium dioxide powder: Mix the liposomes and non-polar nano TiO2 / SiO2 powder evenly to obtain ultrafine titanium dioxide powder.

2. The preparation method according to claim 1, characterized in that, In step S1, the mass ratio of tetrabutyl titanate, tetraethyl orthosilicate, and surfactant is 10 - 15:5 - 8:1 - 2, the adjusted pH value of the solution is 10 - 11, the emulsification condition is 8000 - 10000 r / min, the time is 10 - 15 min, the temperature of the heating and stirring reaction is 50 - 60 °C, the time is 1 - 3 h, and the surfactant is selected from at least one of Tween-20, Tween-40, Tween-60, and Tween-80.

3. The preparation method according to claim 1, wherein In step S3, the mass ratio of the micro-polar nano TiO2 / SiO2 powder to citric acid is 100:15 - 22, and the temperature of the hydrothermal reaction is 200 - 220 °C, and the time is 15 - 20 min.

4. The preparation method according to claim 1, characterized in that, In step S4, the mass ratio of the graphene quantum dot-doped nano TiO2 / SiO2 powder to stearic acid is 10:1 - 2, and the ball milling time is 0.5 - 1.5 h.

5. The preparation method according to claim 1, characterized in that, In step S5, the mass ratio of lecithin, phosphorylcholine polymer, cholesterol, and the coated graphene quantum dot-doped nano TiO2 / SiO2 is 20 - 40:18 - 35:7 - 10:8 - 10, the stirring time is 20 - 30 min, the power of the ultrasonic treatment is 1000 - 1500 W, and the time is 10 - 15 min; the phosphorylcholine polymer is selected from at least one of polyquaternium-51, polyquaternium-61, polyquaternium-64, and polyquaternium-65.

6. The preparation method according to claim 1, characterized in that The mass ratio of the liposome and the non-polar nano-TiO2 / SiO2 powder described in step S6 is 80-90:5-10.

7. An ultrafine titanium dioxide powder prepared by the preparation method according to any one of claims 1-6.

8. Use of the ultrafine titanium dioxide powder according to claim 7 in the field of cosmetics or coatings.

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