Superfine titanium dioxide powder and preparation method thereof

Abstract

The invention provides superfine titanium dioxide powder and a preparation method thereof, and belongs to the technical field of titanium dioxide. The preparation method comprises the following steps: adding tetrabutyl titanate and tetraethoxysilane into a surfactant solution to carry out an emulsification reaction, then calcining twice to prepare non-polar nano TiO2 / SiO2 powder and micro-polar nano TiO2 / SiO2 powder, loading graphene quantum dots and stearic acid on the micro-polar nano TiO2 / SiO2 powder, preparing a liposome, uniformly mixing the liposome with the non-polar nano TiO2 / SiO2 powder, and carrying out ultrasonic dispersion on the liposome so as to prepare the graphene quantum dots / stearic acid loaded liposome. The superfine titanium dioxide powder is prepared. The superfine titanium dioxide powder prepared by the invention has good dispersity, has good skin-friendly, fitting and fine effects when being used in cosmetics, has good antibacterial property and anti-inflammatory property, has excellent anti-ultraviolet performance, and has wide application prospects.

Description

Technical Field

[0001] The present invention relates to the technical field of titanium dioxide, and particularly relates 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, ink, chemical fiber, and cosmetics. Due to the small particle size, large specific surface area, and high surface energy of ultrafine TiO 2 particles, agglomeration, especially hard agglomeration, is likely to occur during the drying and calcination processes, resulting in poor dispersibility of the product, affecting 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 the product performance is not good.

[0003] Chinese Patent CN113896233B discloses a preparation method of low-temperature crystallized titanium dioxide; Chinese Patent CN114162860B discloses a preparation method of titanium dioxide porous spheres; Chinese Patent CN113912109B discloses a preparation method of nano titanium dioxide porous materials; Chinese Patent CN113957506B discloses a preparation method of rutile titanium dioxide plates; Chinese Patent CN113896234B discloses a preparation method of nano titanium dioxide; Chinese Patent Application CN114906873A discloses a preparation method of anatase titanium dioxide. There are various preparation methods of titanium dioxide in the prior art, and most of them 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 Patent CN113896234B, CN113896233B, CN114162860B; or using other substances to make core-shell structured nano titanium dioxide, such as Chinese Patent CN113912109B; or based on the basic sulfuric acid process titanium white production process, titanium white can be prepared, such as Chinese 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, resulting in high production costs. Therefore, it is urgent to study a new preparation method of 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: The present invention provides a method for preparing ultrafine titanium dioxide powder, comprising the following steps: 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; S2. Calcination: The precursor is heated to a first temperature for calcination to obtain non-polar nano TiO 2 / SiO 2 powder; the precursor is heated to a second temperature for calcination to obtain micro-polar nano TiO 2 / SiO 2 powder; S3. Preparation of graphene quantum dot-doped nano TiO 2 / SiO 2 powder: The micro-polar nano TiO 2 / SiO 2 powder is added to a citric acid solution, subjected to hydrothermal reaction, centrifuged, washed, and dried to obtain graphene quantum dot-doped nano TiO 2 / SiO 2 powder; S4. Coating with stearic acid: The graphene quantum dot-doped nano TiO 2 / SiO 2 powder is mixed with stearic acid and ball-milled to obtain coated graphene quantum dot-doped nano TiO 2 / SiO 2 powder; S5. Preparation of liposome: Lecithin, phosphorylcholine polymer and cholesterol are dissolved in an organic solvent, and the coated graphene quantum dot-doped nano TiO 2 / SiO 2 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 liposomes; S6. Preparation of ultrafine titanium dioxide powder: The liposomes and non-polar nano TiO 2 / SiO 2 powder are mixed evenly to obtain ultrafine titanium dioxide powder.

[0006] As a further improvement of the present invention, the mass ratio of tetrabutyl titanate, tetraethyl orthosilicate and surfactant in step S1 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.

[0007] As a further improvement of the present invention, the temperature of the first-temperature calcination in step S2 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.

[0008] As a further improvement of the present invention, in step S3, the mass ratio of the micro-polar nano TiO 2 / SiO 2 powder and citric acid is 100:15-22, the temperature of the hydrothermal reaction is 200-220 °C, and the time is 15-20 min.

[0009] As a further improvement of the present invention, in step S4, the mass ratio of the graphene quantum dot-doped nano TiO 2 / SiO 2 powder and stearic acid is 10:1-2, and the ball milling time is 0.5-1.5 h.

[0010] As a further improvement of the present invention, in step S5, the mass ratio of lecithin, phosphorylcholine polymer, cholesterol, and the coated graphene quantum dot-doped nano TiO 2 / SiO 2 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 2-methacryloyloxyethyl phosphorylcholine homopolymer, 2-methacryloyloxyethyl phosphorylcholine, polyphosphorylcholine ethylene glycol acrylate, and polyphosphorylcholine n-butyl methacrylate.

[0011] As a further improvement of the present invention, in step S6, the mass ratio of the liposome and the non-polar nano TiO 2 / SiO 2 powder is 80-90:5-10.

[0012] The present invention further protects an ultrafine titanium dioxide powder prepared by the above preparation method.

[0013] The present invention further protects an application of the above-mentioned ultrafine titanium dioxide powder in the fields of cosmetics or coatings.

[0014] The present invention has the following beneficial effects: Due to the large specific surface area and numerous surface vacant bonds of nano-TiO 2 it is extremely easy to agglomerate during the preparation and application processes, and its excellent properties cannot be fully exerted. In the present invention, tetraethyl orthosilicate and tetrabutyl titanate are mixed and added to a surfactant solution, and after emulsification, tiny nano-sized oil-in-water droplets are formed, and the sol-gel reaction is rapidly catalyzed to obtain a nano-sized precursor, which is calcined at different temperature ranges. Calcination at 700 - 800 °C yields non-polar nano-TiO 2 / SiO 2 powder containing rutile-type titanium dioxide. Among them, rutile-type titanium dioxide belongs to the tetragonal system, is relatively dense and stable, and its symmetric structure makes it non-polar. Calcination at 400 - 500 °C yields micro-polar nano-TiO 2 / SiO 2 powder containing anatase-type titanium dioxide. Among them, the octahedra of anatase TiO 2 show obvious orthorhombic crystal distortion, and the Ti-O bond distances are all very small and unequal. This imbalance makes the TiO 2 molecule highly polar, enabling the TiO 2 surface to easily adsorb water molecules and polarize the water molecules to form surface hydroxyl groups, which can better complete subsequent surface modification. In addition, the prepared nano-TiO 2 / SiO 2 powder surface is covered with a silicon-oxygen layer, and silicon precipitates on the surface of titanium dioxide particles in the form of Si(OH) 4 . Monomeric orthosilicic acid polymerizes at different rates, initially precipitating monomeric orthosilicic acid or low-polymerization-degree silicic acid polymers. The highly active reactive silicon firmly bonds to the surface hydroxyl groups of titanium dioxide, forming nucleation sites on the titanium dioxide surface. On these nucleation sites, it can quickly react with TiO 2 to form Ti-O-Si bonds, generating titanium-oxygen and silicon-oxygen composite nanoparticles. Blending with SiO 2 makes the prepared nano-TiO 2 / SiO 2 powder surface carry negative charges, thus making its nano-structure not easily agglomerate.

[0015] In natural sunlight, UVA accounts for 90%-95% of the total amount of ultraviolet rays reaching the Earth's surface, while UVB only accounts for 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 0.1 μm has strong light scattering properties and mainly blocks UVA; titanium dioxide with a particle size less than 0.1 μm has a relatively small particle size and relatively weak light scattering, and its sun protection mainly absorbs UVB.

[0016] The non-polar nano-TiO 2 / SiO 2 powder (with a particle size less than 0.1 μm) has a good absorption effect on UVB, while the prepared micro-polar nano-TiO 2 / SiO 2 powder has a relatively small particle size and needs further modification.

[0017] In the present invention, the prepared micro-polar nano-TiO 2 / SiO 2 powder, due to the presence of hydroxyl groups on its surface, 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 TiO 2 can utilize the visible light region, enhances its photocatalytic antibacterial and chemical stability, and improves the anti-inflammatory effect.

[0018] Furthermore, the prepared nano-TiO 2 / SiO 2 powder doped with graphene quantum dots, after being coated and modified with stearic acid, forms a bidentate complex with carboxylic acid, can exist uniformly and stably in the organic phase, thereby improving its dispersibility and further avoiding its agglomeration. 4+ 2

[0019] In the present invention, the prepared nano-TiO 2 / SiO 2 powder coated with graphene quantum dots doped, after being coated with lecithin and cholesterol to form liposomes, improves the water dispersibility of the material, and further improves the dispersion performance of the material, making the material have good hydrophilicity, and has a more skin-friendly, more fitting and delicate effect when used as a cosmetic material.

[0020] The ultrafine titanium dioxide powder prepared in 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 anti-ultraviolet performance, and has broad application prospects. Specific embodiments

[0021] 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.

[0022] Embodiment 1: This embodiment provides a method for preparing ultrafine titanium dioxide powder, which includes the following steps: S1. Preparation of the precursor: Drop 200 mL of a dichloromethane solution containing 10 g of tetrabutyl titanate and 5 g of tetraethyl orthosilicate into 500 mL of an aqueous solution containing 1 g of Tween-20, adjust the pH value of the solution to 10, emulsify at 8000 r / min for 15 min, heat to 60 °C, stir and react for 1 h, centrifuge, wash, and dry to obtain the precursor; S2. Calcination: Heat the precursor to 850 °C and calcine for 2 h to obtain non-polar nano-TiO 2 / SiO 2 powder; Heat the precursor to 400 °C and calcine for 2 h to obtain micro-polar nano-TiO 2 / SiO 2 powder; S3. Preparation of graphene quantum dot-doped nano-TiO 2 / SiO 2 powder: Add 10 g of micro-polar nano-TiO 2 / SiO 2 powder to 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-TiO 2 / SiO 2 powder; S4. Coating with stearic acid: Mix 10 g of graphene quantum dot-doped nano-TiO 2 / SiO 2 powder with 1 g of stearic acid, ball mill for 0.5 h to obtain coated graphene quantum dot-doped nano-TiO 2 / SiO 2 powder; 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 (the volume ratio of dichloromethane to ethanol is 1:1), add 8 g of coated graphene quantum dot-doped nano-TiO 2 / SiO 2 , 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; S6. Preparation of ultrafine titanium dioxide powder: 8 g of liposomes and 0.5 g of non-polar nano TiO 2 / SiO 2 powders were stirred and mixed for 10 min to obtain ultrafine titanium dioxide powder.

[0023] Example 2: This example provides a method for preparing ultrafine titanium dioxide powder, which includes the following steps: S1. Preparation of precursor: A dichloromethane solution containing 15 g of tetrabutyl titanate and 8 g of tetraethyl orthosilicate in 200 mL was dropped into an aqueous solution containing 2 g of Tween-40 in 500 mL. The pH value of the solution was adjusted to 11, emulsified at 10000 r / min for 15 min, heated to 50 °C, stirred and reacted for 3 h, centrifuged, washed, and dried to obtain the precursor; S2. Calcination: The precursor was heated to 900 °C and calcined for 4 h to obtain non-polar nano TiO 2 / SiO 2 powders; the precursor was heated to 500 °C and calcined for 4 h to obtain micro-polar nano TiO 2 / SiO 2 powders; S3. Preparation of graphene quantum dot-doped nano TiO 2 / SiO 2 powders: 10 g of micro-polar nano TiO 2 / SiO 2 powders were added to an aqueous solution containing 2.2 g of citric acid in 200 mL, hydrothermally reacted at 220 °C for 20 min, centrifuged, washed, and dried to obtain graphene quantum dot-doped nano TiO 2 / SiO 2 powders; S4. Coating with stearic acid: 10 g of graphene quantum dot-doped nano TiO 2 / SiO 2 powders were mixed with 2 g of stearic acid and ball-milled for 1.5 h to obtain coated graphene quantum dot-doped nano TiO 2 / SiO 2 powders; S5. Preparation of liposomes: 40 g of lecithin, 10 g of 2-methacryloyloxyethyl phosphorylcholine, and 35 g of cholesterol were dissolved in a mixed solution of 500 mL of dichloromethane and ethanol (the volume ratio of dichloromethane to ethanol was 1:1), 10 g of coated graphene quantum dot-doped nano TiO 2 / SiO 2 was added, stirred for 30 min, the organic solvent was removed by rotary evaporation under reduced pressure, 200 mL of water was added, ultrasonic treatment was carried out at 1500 W for 15 min, and freeze-dried to obtain liposomes; S6. Preparation of ultrafine titanium dioxide powder: Mix 9 g of liposomes and 1 g of non-polar nano TiO 2 / SiO 2 powder by stirring for 10 min to obtain ultrafine titanium dioxide powder.

[0024] Example 3: This example provides a method for preparing ultrafine titanium dioxide powder, including the following steps: S1. Preparation of precursor: Drop 200 mL of dichloromethane solution containing 12 g of tetrabutyl titanate and 6 g of tetraethyl orthosilicate into 500 mL of 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; S2. Calcination: Heat the precursor to 870 °C and calcine for 3 h to obtain non-polar nano TiO 2 / SiO 2 powder; Heat the precursor to 450 °C and calcine for 3 h to obtain micro-polar nano TiO 2 / SiO 2 powder; S3. Preparation of graphene quantum dot-doped nano TiO 2 / SiO 2 powder: Add 10 g of micro-polar nano TiO 2 / SiO 2 powder to 200 mL of aqueous solution containing 2 g of citric acid, perform hydrothermal reaction at 210 °C for 17 min, centrifuge, wash, and dry to obtain graphene quantum dot-doped nano TiO 2 / SiO 2 powder; S4. Coating with stearic acid: Mix 10 g of graphene quantum dot-doped nano TiO 2 / SiO 2 powder with 1.5 g of stearic acid, ball mill for 1 h to obtain coated graphene quantum dot-doped nano TiO 2 / SiO 2 powder; 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 mixed solution of dichloromethane and ethanol (volume ratio of dichloromethane to ethanol is 1:1), add 9 g of coated graphene quantum dot-doped nano TiO 2 / SiO 2 , 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 freeze-dry to obtain liposomes; S6. Preparation of ultrafine titanium dioxide powder: 8.5 g of liposomes and 0.7 g of non-polar nano TiO 2 / SiO 2 powder are stirred and mixed for 10 min to obtain ultrafine titanium dioxide powder.

[0025] Comparative Example 1 Compared with Example 3, the difference is that tetraethyl orthosilicate is not added in step S1.

[0026] Specifically as follows: S1. Preparation of precursor: A dichloromethane solution containing 18 g of tetrabutyl titanate in 200 mL is dropped into an aqueous solution containing 1.5 g of Tween-80 in 500 mL, the pH value of the solution is 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.

[0027] Comparative Example 2 Compared with Example 3, the difference is that step S3 is not carried out.

[0028] Specifically as follows: S1. Preparation of precursor: A dichloromethane solution containing 12 g of tetrabutyl titanate and 6 g of tetraethyl orthosilicate in 200 mL is dropped into an aqueous solution containing 1.5 g of Tween-80 in 500 mL, the pH value of the solution is 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; S2. Calcination: The precursor is heated to 870 °C and calcined for 3 h to obtain non-polar nano TiO 2 / SiO 2 powder; the precursor is heated to 450 °C and calcined for 3 h to obtain micro-polar nano TiO 2 / SiO 2 powder; S3. Coating with stearic acid: 10 g of graphene quantum dot-doped nano TiO 2 / SiO 2 powder is mixed with 1.5 g of stearic acid and ball-milled for 1 h to obtain graphene quantum dot-doped nano TiO 2 / SiO 2 powder; S4. Preparation of liposomes: 30 g of lecithin, 8.5 g of 2-methacryloyloxyethyl phosphorylcholine and 25 g of cholesterol are dissolved in a mixed solution of 500 mL of dichloromethane and ethanol (the volume ratio of dichloromethane to ethanol is 1:1), and 9 g of graphene quantum dot-doped nano TiO 2 / SiO 2, 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 freeze-dry to obtain liposomes; S5. Preparation of ultrafine titanium dioxide powder: Mix 8.5 g of liposomes and 0.7 g of non-polar nano-TiO 2 / SiO 2 powder by stirring for 10 min to obtain ultrafine titanium dioxide powder.

[0029] Comparative Example 3 Compared with Example 3, the difference is that step S4 is not carried out.

[0030] Specifically as follows: 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; S2. Calcination: Heat the precursor to 870 °C and calcine for 3 h to obtain non-polar nano-TiO 2 / SiO 2 powder; Heat the precursor to 450 °C and calcine for 3 h to obtain micro-polar nano-TiO 2 / SiO 2 powder; S3. Preparation of graphene quantum dot-doped nano-TiO 2 / SiO 2 powder: Add 10 g of micro-polar nano-TiO 2 / SiO 2 powder to 200 mL of an aqueous solution containing 2 g of citric acid, perform hydrothermal reaction at 210 °C for 17 min, centrifuge, wash, and dry to obtain graphene quantum dot-doped nano-TiO 2 / SiO 2 powder; 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-TiO 2 / SiO 2 , 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 freeze-dry to obtain liposomes; S5. Preparation of ultrafine titanium dioxide powder: Mix 8.5 g of liposomes and 0.7 g of non-polar nano-TiO 2 / SiO2 The powder is stirred and mixed for 10 min to obtain ultrafine titanium dioxide powder.

[0031] Comparative Example 4 Compared with Example 3, the difference lies in that step S5 is not carried out.

[0032] Specifically as follows: S1. Preparation of precursor: A dichloromethane solution containing 12 g of tetrabutyl titanate and 6 g of tetraethyl orthosilicate in 200 mL is dropped into an aqueous solution containing 1.5 g of Tween-80 in 500 mL. The pH value of the solution is 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; S2. Calcination: The precursor is heated to 870 °C and calcined for 3 h to obtain non-polar nano TiO 2 / SiO 2 powder; The precursor is heated to 450 °C and calcined for 3 h to obtain micro-polar nano TiO 2 / SiO 2 powder; S3. Preparation of graphene quantum dot-doped nano TiO 2 / SiO 2 powder: 10 g of micro-polar nano TiO 2 / SiO 2 powder is 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 TiO 2 / SiO 2 powder; S4. Coating with stearic acid: 10 g of graphene quantum dot-doped nano TiO 2 / SiO 2 powder is mixed with 1.5 g of stearic acid and ball-milled for 1 h to obtain coated graphene quantum dot-doped nano TiO 2 / SiO 2 powder; S5. Preparation of ultrafine titanium dioxide powder: 8.5 g of coated graphene quantum dot-doped nano TiO 2 / SiO 2 powder and 0.7 g of non-polar nano TiO 2 / SiO 2 powder are stirred and mixed for 10 min to obtain ultrafine titanium dioxide powder.

[0033] Comparative Example 5 Compared with Example 3, the difference lies in that in step S6, liposomes and non-polar nano TiO 2 / SiO 2The mass ratio of the powder is 0.7:8.5.

[0034] Comparative Example 6 Compared with Example 3, the difference lies in that non-polar nano-TiO 2 / SiO 2 powder was not added in step S6.

[0035] Comparative Example 7 Compared with Example 3, the difference lies in that liposomes were not added in step S6.

[0036] Test Example 1 Detection of Photosensitivity Color Difference The product obtained in Examples 1-3 or Comparative Examples 1-7 was 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 its L ∗ , a ∗ , b ∗ value was measured using a colorimeter (CM508D, Minolta, Japan). The D25 light source was used, and the angle was 10°. The operation was carried out avoiding sunlight. The above sample plate was taken out after being irradiated in an aging instrument (CI3000, TLAS, USA) for 30 min, and immediately the L ∗ , a ∗ , b ∗ value after light irradiation was measured, and the color difference ΔE of the sample before and after light irradiation was calculated using the following formula. The results are shown in Table 1.

[0037] ΔE =

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

[0038] As can be seen from the above table, the ΔE of the ultrafine titanium dioxide powder obtained in Examples 1-3 of the present invention is lower, the photoactivity is low, and the performance is more stable.

[0039] Test Example 2 SPF Value Detection The product obtained in Examples 1-3 or Comparative Examples 1-7 was fully mixed evenly with sericite in a powder mixer at a ratio of 1:10. The sample was applied at 0.75 mg / cm 2Apply the measured amount to the tape for standby. During measurement, first conduct a blank test with the tape. Use an SPF290 measuring instrument to quantitatively analyze the sun protection effect of the sample. Define the monochromatic light protection factor MPF λ as the blocking ability of the sample to monochromatic light with a wavelength of λ, and its magnitude is the transmittance T λ of the light at this wavelength. That is, MPF λ = 1 / T λ . The results are shown in Table 2.

[0040] Define the comprehensive sun protection factor SPF value in the UVA and UVB ranges as follows: ; where E λ is the light factor, and B λ is the erythema factor, which respectively characterize the ultraviolet intensity at wavelength λ and the degree of erythema that may be caused to the skin.

[0041] Table 2

[0042] As can be seen from the above table, the ultrafine titanium dioxide powder prepared in Examples 1-3 of the present invention has a relatively high SPF value and has a good anti-ultraviolet radiation effect.

[0043] Test Example 3 Prepare a 10wt% aqueous dispersion of the product prepared in Examples 1-3 or Comparative Examples 1-7, add 1wt% of the dispersant sodium silicate, and use a ZETAPLUS potentiometer to measure the ζ potential. The results are shown in Table 3.

[0044] Table 3

[0045] 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 is negative in water, and the dispersibility is good.

[0046] Test Example 4 Use a 3-FLEX 3500 multi-station high-throughput gas adsorption instrument to measure the specific surface area of the product prepared in Examples 1-3 or Comparative Examples 1-7. The results are shown in Table 4.

[0047] Table 4

[0048] As can be seen from the above table, the ultrafine titanium dioxide powder prepared in Examples 1-3 of the present invention has a relatively large specific surface area.

[0049] 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: The following steps are involved: S1. Preparation of precursor: dropping a mixed solution of tetrabutyl titanate and ethyl orthosilicate into a surfactant solution, adjusting the pH value of the solution, emulsifying, heating and stirring the reaction, centrifuging, washing, and drying to obtain a precursor; S2 Calcination: The precursor is heated to a first temperature and calcined to obtain a non-polar nano-TiO2 / SiO2 powder; the precursor is heated to a second temperature and calcined to obtain a slightly polar nano-TiO2 / SiO2 powder; S3. Preparation of graphene quantum dot-doped nano-TiO2 / SiO2 powder: adding slightly polar nano-TiO2 / SiO2 powder to a citric acid solution, hydrothermally reacting, centrifuging, washing, and drying to obtain graphene quantum dot-doped nano-TiO2 / SiO2 powder; S4 stearic acid coating: The graphene quantum dot-doped nano-TiO2 / SiO2 powder was mixed with stearic acid and ball-milled to obtain graphene quantum dot-doped nano-TiO2 / SiO2 powder; S5. Preparation of liposomes: dissolving lecithin, phosphorylcholine polymer and cholesterol in an organic solvent, adding nano-TiO2 / SiO2 doped with graphene quantum dots, stirring, removing the organic solvent under reduced pressure, adding water, ultrasonic treatment, freeze drying, and obtaining liposomes; S6. Preparation of ultrafine titanium dioxide powder: The liposomes and non-polar nano-TiO2 / SiO2 powders are mixed 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 pH value of the adjusted solution is 10-11, the emulsification conditions are 8000-10000r / min, the time is 10-15min, the temperature of the heated stirring reaction is 50-60°C, the time is 1-3h, 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, characterized in that: In step S2, the first temperature calcination temperature is 800-900°C, and the time is 2-4h; the second temperature calcination temperature is 400-500°C, and the time is 2-4h.

4. The preparation method according to claim 1, characterized in that: In step S3, the mass ratio of the slightly 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 minutes.

5. 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 0.5-1.5h.

6. The preparation method according to claim 1, characterized in that: 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.

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

8. An ultrafine titanium dioxide powder obtained by the preparation method according to any one of claims 1 to 7.

9. An application of the ultrafine titanium dioxide powder as claimed in claim 8 in the field of cosmetics or coatings.

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