A modified titanium dioxide and its preparation method and application

Abstract

The present invention relates to a modified titanium dioxide, its preparation method, and application. The preparation method comprises the following steps: first, subjecting titanium dioxide to composite organic modification using graphene oxide and a titanate coupling agent to obtain a composite powder; then, coating the composite powder with a sodium metaaluminate solution and then a sodium silicate solution to obtain the modified titanium dioxide. This modified titanium dioxide exhibits excellent dispersion stability, mechanical strength, and high-temperature resistance. Its use in the preparation of 3D-printed ceramic materials can enhance the weather resistance and service life of the 3D-printed ceramic materials.

Description

Technical Field

[0001] The present invention relates to the technical field of modified titanium dioxide, and in particular to a modified titanium dioxide and a preparation method and application thereof. Background Art

[0002] Unmodified titanium dioxide presents multiple problems. First, its particle size distribution is uneven and ranges widely, which not only affects the hiding power and glossiness of titanium dioxide, but can also lead to uneven dispersion in 3D-printed ceramic materials, thus affecting the printing effect. Second, titanium dioxide has a high surface energy and is prone to self-agglomeration, resulting in reduced dispersion stability, which may weaken the overall stability and printing quality of the printed ceramic material. Furthermore, titanium dioxide is highly hygroscopic and easily absorbs moisture from the air to form lumps, which not only brings inconvenience to storage and transportation but also affects its effectiveness in 3D-printed ceramic materials. In addition, unmodified titanium dioxide has strong photocatalytic activity due to its own lattice defects. When exposed to sunlight, it easily produces active groups with high oxidizing ability, which may accelerate the oxidative degradation of organic resins in the surrounding environment, thereby shortening the weather resistance and service life of ceramic products. Summary of the Invention

[0003] The purpose of the present invention is to overcome the shortcomings of the prior art and provide a modified titanium dioxide having good high temperature stability, chemical stability and wear resistance, as well as a preparation method and application thereof.

[0004] To achieve the above object, the technical solution adopted by the present invention is:

[0005] In a first aspect, the present invention provides a method for preparing a modified titanium dioxide, comprising the following steps:

[0006] S1. Ultrasonic dispersion of titanium dioxide in a 75% volume concentration of ethanol aqueous solution to obtain a titanium dioxide slurry, adding a titanate coupling agent and graphene oxide, and adjusting the pH of the system to 3-4 with glacial acetic acid. The mixture is heated to 85-95°C and stirred for reaction for 5-6 hours. The mixture is centrifuged, washed with water, vacuum dried, and then crushed to obtain a composite powder; wherein the titanium dioxide is nano-scale rutile titanium dioxide with a particle size of 50-300 nm, the graphene oxide is nano-scale graphene oxide with a single-layer diameter of 50-300 nm, and the mass ratio of the titanium dioxide, graphene oxide, and titanate coupling agent is (3-5):1:1;

[0007] S2. Ultrasonic dispersion of the composite powder in water to obtain a composite slurry, heating the composite slurry to 80-90° C. and then keeping it warm, adjusting the pH of the system to 6-6.5, adding a sodium aluminate solution for coating treatment for 1-3 hours, adjusting the pH of the system to 8-8.5, adding a sodium silicate solution for coating treatment for 1-3 hours, aging, filtering, washing with water, drying, and pulverizing to obtain the modified titanium dioxide.

[0008] Preferably, in step S1, the mass ratio of the titanium dioxide to the ethanol aqueous solution is 1:(2-3).

[0009] Preferably, in step S1, the ultrasonic power is 130-250 W, the ultrasonic temperature is 45-55° C., and the ultrasonic time is 0.8-1.2 h.

[0010] Preferably, in step S1, the stirring reaction speed is 300-500 r / min; the drying temperature is 70-80° C. and the drying time is 2-3 h; and the pulverization is performed using a jet mill to pulverize the product to a particle size of 0.2-0.5 μm.

[0011] Preferably, in step S2, the ultrasonic power is 130-250 W, the ultrasonic temperature is 45-55° C., and the ultrasonic time is 0.8-1.2 h.

[0012] Preferably, in step S2, the mass ratio of the composite powder to water is 1:(2-3).

[0013] Preferably, in step S2, the mass concentration of the sodium metaaluminate solution is 10-40 g / L, and the mass ratio of the composite slurry to the sodium metaaluminate solution is 1:(0.1-1).

[0014] Preferably, in step S2, the mass concentration of the sodium silicate solution is 20-60 g / L, and the mass ratio of the composite slurry to the sodium silicate solution is 1:(0.1-1).

[0015] Preferably, in step S2, the aging temperature is 80-100° C. and the aging time is 1-3 hours; the drying temperature is 70-90° C. and the drying time is 1-2 hours; and the powder is crushed to obtain a 100-200 mesh powder.

[0016] In a second aspect, the present invention provides a modified titanium dioxide prepared by the preparation method of the modified titanium dioxide provided in the first aspect.

[0017] In a third aspect, the present invention provides a use of the modified titanium dioxide described in the second aspect in the preparation of 3D printing ceramic materials.

[0018] Compared with the prior art, the present invention has the following beneficial effects:

[0019] The present invention adopts the method of first organic modification and then inorganic coating to modify titanium dioxide, so that the modified titanium dioxide has good dispersion stability, mechanical strength, and high temperature resistance, and has good application prospects in 3D printing ceramic materials. Specifically, the present invention first uses graphene oxide and titanate coupling agent to perform composite organic modification on titanium dioxide, which not only reduces the agglomeration phenomenon of titanium dioxide, improves the dispersion ability of titanium dioxide, enhances the application stability of titanium dioxide, but also further improves the mechanical properties and weather resistance of titanium dioxide; then, the present invention uses sodium aluminate solution and sodium silicate solution in sequence to coat the titanium dioxide after composite organic modification, forming a uniform and dense coating film, which effectively blocks the photochemical points of titanium dioxide, reduces the generation of high oxidation active groups, and further enhances the weather resistance and service life of titanium dioxide. The modified titanium dioxide prepared by the preparation method of the present invention effectively solves the problems existing in unmodified titanium dioxide, improves its application performance in 3D printing ceramic materials, enhances the weather resistance and service life of 3D printing ceramic materials, and provides strong support for the development of 3D printing ceramic technology. DETAILED DESCRIPTION

[0020] In order to better illustrate the purpose, technical solutions and advantages of the present invention, the present invention will be further described below in conjunction with specific embodiments.

[0021] The sources of the raw materials used in the following examples and comparative examples are as follows:

[0022] Titanium dioxide: rutile titanium dioxide, manufactured by Pangang Titanium Industry, model NR-508L, TiO2 content ≥80%, rutile content ≥98%, average particle size 0.052μm;

[0023] Isopropyl tris(dioctyl pyrophosphate) titanate: manufacturer: Tianjin Xiensi Biochemical Technology Co., Ltd., model number: I-0308797;

[0024] Graphene oxide: The manufacturer is Zhongke Yueda (Shanghai) Materials Technology Co., Ltd., in powder form, with an average flake size of <300nm, an average number of flake layers: a monolayer rate of >98%, and a metal impurity content of ≤0.1%;

[0025] Sodium metaaluminate: manufacturer is Shandong Lier New Materials Co., Ltd., model number 54#, Na2Al2O4 ≥ 85.0%, Al2O3 ≥ 53.0%, Na2O ≥ 38.0%;

[0026] Powdered sodium silicate (instant sodium silicate); manufacturer: Foshan Zhongfa Water Glass Factory, model 3.0, modulus 3.0, Na2O content 22.0-26.0%, SiO2 content 55.0-66.0%,

[0027] Alumina: Manufacturer: Guangdong Wengjiang Chemical Reagent Co., Ltd., model number MA00327;

[0028] Zirconium oxide: manufacturer: Guangdong Wengjiang Chemical Reagent Co., Ltd., model number PA00898;

[0029] Room temperature Vickers hardness tester: manufacturer: Shenzhen Senyu Instrument Equipment Co., Ltd., model: HV-1000, item number: SY081348133;

[0030] High-temperature Vickers hardness tester: manufacturer: Zibo Diye Instrument Equipment Co., Ltd., model: HLT-X7;

[0031] Unless otherwise specified, other materials and reagents used in the examples can be obtained from commercial sources.

[0032] Example 1

[0033] A method for preparing modified titanium dioxide comprises the following steps:

[0034] S1. Ultrasonic dispersion of titanium dioxide in a 75% volume concentration ethanol aqueous solution at 200W and 50°C to obtain a titanium dioxide slurry, adding a titanate coupling agent and graphene oxide, and adjusting the pH of the system to 3 with glacial acetic acid. After heating to 90°C, stirring and reacting at a speed of 400r / min for 5h, centrifuging, washing with water, and vacuum drying at 80°C for 2h, and crushing with a jet mill to obtain a composite powder with a particle size of 0.3μm; wherein the mass ratio of the titanium dioxide to the ethanol aqueous solution is 1:2, the ultrasonic time is 1h, the mass ratio of the titanium dioxide, graphene oxide and titanate coupling agent is 4:1:1, and the titanate coupling agent is isopropyl tris(dioctyl pyrophosphate) titanate;

[0035] S2. Ultrasonic dispersion of the composite powder in water at 200 W and 50 ° C to obtain a composite slurry, heat the composite slurry to 80 ° C and keep it warm, adjust the pH of the system to 6, add a sodium aluminate solution with a mass concentration of 30 g / L for coating treatment for 2 hours, then adjust the pH of the system to 8, add a sodium silicate solution with a mass concentration of 40 g / L for coating treatment for 2 hours, mature at 90 ° C for 2 hours, filter, wash with water, vacuum dry at 80 ° C for 1 hour, and crush with a jet mill to obtain a modified titanium dioxide with a particle size of 150 mesh, wherein the mass ratio of the composite powder to water is 1:2, the ultrasonic time is 1 hour, the mass ratio of the composite slurry to the sodium aluminate solution is 1:0.8, and the mass ratio of the composite slurry to the sodium silicate solution is 1:0.6.

[0036] Example 2

[0037] A method for preparing modified titanium dioxide comprises the following steps:

[0038] S1. Ultrasonic dispersion of titanium dioxide in a 75% volume concentration ethanol aqueous solution at 130W and 45°C to obtain a titanium dioxide slurry, adding a titanate coupling agent and graphene oxide, and adjusting the pH of the system to 3 with glacial acetic acid. After heating to 85°C, stirring and reacting at a speed of 300r / min for 5h, centrifuging, washing with water, and vacuum drying at 70°C for 3h, and crushing with a jet mill to obtain a composite powder with a particle size of 0.2μm; wherein the mass ratio of the titanium dioxide to the ethanol aqueous solution is 1:2, the ultrasonic time is 1.2h, the mass ratio of the titanium dioxide, graphene oxide and titanate coupling agent is 3:1:1, and the titanate coupling agent is isopropyl tris(dioctyl pyrophosphate) titanate;

[0039] S2. Ultrasonic dispersion of the composite powder in water at 130W and 45°C to obtain a composite slurry, heating the composite slurry to 75°C and then keeping it warm, adjusting the pH of the system to 6, adding a sodium aluminate solution with a mass concentration of 10g / L for coating treatment for 3h, then adjusting the pH of the system to 8, adding a sodium silicate solution with a mass concentration of 20g / L for coating treatment for 3h, aging at 80°C for 3h, filtering, washing with water, and vacuum drying at 70°C for 2h. Processing with a jet mill to obtain a modified titanium dioxide with a particle size of 100 mesh, wherein the mass ratio of the composite powder to water is 1:2, the ultrasonic time is 0.8h, the mass ratio of the composite slurry to the sodium aluminate solution is 1:0.1, and the mass ratio of the composite slurry to the sodium silicate solution is 1:0.1.

[0040] Example 3

[0041] A method for preparing modified titanium dioxide comprises the following steps:

[0042] S1. Ultrasonic dispersion of titanium dioxide in a 75% volume concentration ethanol aqueous solution at 250W and 55°C to obtain a titanium dioxide slurry, adding a titanate coupling agent and graphene oxide, and adjusting the pH of the system to 4 with glacial acetic acid. After heating to 95°C, stirring and reacting at a speed of 500r / min for 5h, centrifuging and washing with water, and then vacuum drying at 75°C for 2h, and treating with a jet mill to obtain a composite powder with a particle size of 0.5μm; wherein the mass ratio of the titanium dioxide to the ethanol aqueous solution is 1:3, the ultrasonic time is 0.8h, the mass ratio of the titanium dioxide, graphene oxide and titanate coupling agent is 5:1:1, and the titanate coupling agent is isopropyl tris(dioctyl pyrophosphate acyloxy) titanate;

[0043] S2. Ultrasonic dispersion of the composite powder in water at 250W and 55°C to obtain a composite slurry, heating the composite slurry to 85°C and keeping it warm, adjusting the pH of the system to 6.5, adding a sodium aluminate solution with a mass concentration of 10g / L for coating treatment for 3h, then adjusting the pH of the system to 8, adding a sodium silicate solution with a mass concentration of 20g / L for coating treatment for 3h, aging at 100°C for 1h, filtering, washing with water, vacuum drying at 90°C for 1h, and crushing with a jet mill to obtain modified titanium dioxide with a particle size of 200mesh, wherein the mass ratio of the composite powder to water is 1:3, the ultrasonic time is 1.2h, the mass ratio of the composite slurry to the sodium aluminate solution is 1:1, and the mass ratio of the composite slurry to the sodium silicate solution is 1:1.

[0044] Comparative Example 1

[0045] The difference between Comparative Example 1 and Example 1 is that inorganic coating is performed first, and then organic modification is performed. The specific steps are as follows:

[0046] S1. Ultrasonic dispersion of titanium dioxide in water at 200W and 50°C to obtain titanium dioxide slurry, heating the titanium dioxide slurry to 80°C and then keeping it warm, adjusting the pH of the system to 6, adding a sodium aluminate solution with a mass concentration of 30g / L for coating treatment for 2h, then adjusting the pH of the system to 8, adding a sodium silicate solution with a mass concentration of 40g / L for coating treatment for 2h, aging at 90°C for 2h, filtering, washing with water, vacuum drying at 80°C for 1h, and crushing with a jet mill to obtain coated titanium dioxide with a particle size of 0.3μm, wherein the mass ratio of the composite powder to water is 1:2, the ultrasonic time is 1h, the mass ratio of the titanium dioxide slurry to the sodium aluminate solution is 1:0.8; the mass ratio of the titanium dioxide slurry to the sodium silicate solution is 1:0.6;

[0047] S2. Ultrasonic disperse the coated titanium dioxide in a 75% volume concentration of ethanol aqueous solution at 200 W and 50 ° C to obtain a slurry, add a titanate coupling agent and graphene oxide, and adjust the pH of the system to 3 with glacial acetic acid. After heating to 90 ° C, stir and react at a speed of 400 r / min for 5 hours, centrifuge, wash with water, and vacuum dry at 80 ° C for 2 hours. Use a jet mill to pulverize to obtain a modified titanium dioxide with a particle size of 150 mesh, wherein the mass ratio of coated titanium dioxide to water is 1:2, the ultrasonic time is 1 hour, the mass ratio of coated titanium dioxide, graphene oxide and titanate coupling agent is 4:1:1, and the titanate coupling agent is isopropyl tris (dioctyl pyrophosphate) titanate.

[0048] Comparative Example 2

[0049] The difference between Comparative Example 2 and Example 1 is that: in Comparative Example 2, graphene oxide is not added, and an equal amount of titanate coupling agent is used to make up for the missing amount.

[0050] Comparative Example 3

[0051] The difference between Comparative Example 3 and Example 1 is that in Comparative Example 3, no titanate coupling agent is added, and an equal amount of graphene oxide is used to make up for the missing amount.

[0052] Comparative Example 4

[0053] The difference between Comparative Example 4 and Example 1 is that the total amount of titanium dioxide, graphene oxide and titanate coupling agent remains unchanged, and the mass ratio of titanium dioxide, graphene oxide and titanate coupling agent is 2:1:1.

[0054] Comparative Example 5

[0055] The difference between Comparative Example 5 and Example 1 is that the total amount of titanium dioxide, graphene oxide and titanate coupling agent remains unchanged, and the mass ratio of titanium dioxide, graphene oxide and titanate coupling agent is 6:1:1.

[0056] Performance Testing

[0057] 1. Acid solubility test

[0058] The modified titanium dioxide from Examples 1-3 and Comparative Examples 1-5 was tested for acid solubility as follows: 0.2 g of modified titanium dioxide was added to 10 mL of 98% sulfuric acid, ultrasonically dispersed for 1 minute, and then dissolved at 180°C for 1 hour. After cooling the sample to room temperature, the volume was adjusted to 100 mL with water and filtered. 10 mL of the filtrate was pipetted, 10 mL of 30% hydrogen peroxide solution was added, and the resulting solution was diluted to 100 mL with 10% sulfuric acid solution. After 1 hour, the solution absorbance was measured at 400 nm, and the amount of titanium dioxide dissolved in the corresponding modified titanium dioxide was calculated using a standard curve. See Table 1 for details.

[0059] Table 1 Acid solubility of modified titanium dioxide samples

[0060]

[0061]

[0062] 2. High temperature resistance test

[0063] Ceramic materials for 3D printing were prepared with the following specific formula: 15 parts by mass of a mixed powder of aluminum oxide and zirconium oxide and 10 parts by mass of modified titanium dioxide (Examples 1-4, Comparative Examples 1-5); wherein, the preparation method of the mixed powder of aluminum oxide and zirconium oxide was as follows: aluminum oxide and zirconium oxide with a mass ratio of 1.5:1 were soaked in 75% alcohol, and then placed in a planetary ball mill for vacuum crushing, wherein the mass ratio of steel balls to mixed powder was 4:1, and insulating tape was wrapped around to prevent static electricity. The speed was 200 rpm, and the ball milling was performed for 4 hours. The powder after ball milling was dried at 80°C to dry out all moisture and then agglomerated; after simple grinding treatment, it was filtered through a 100-mesh sieve to obtain a mixed powder of zinc oxide and zirconium oxide.

[0064] Each set of 3D printing ceramic materials was fed into an SLM printer for laser 3D printing. Laser 3D printing process parameters were set to: laser power of 150W, scan rate of 1200m / s, scan pitch of 0.1mm, substrate preheat temperature of 200°C, layer thickness of 30μm, and laser spot diameter of 70μm. The resulting 3D printed workpieces were rectangular pieces measuring 10mm × 10mm × 12mm. To increase sample stability on the substrate, the first layer was printed twice.

[0065] The hardness of the printed workpieces of each group was tested at room temperature (25±5℃) and heated at 500℃ for 1h. The room temperature hardness was measured using a Vickers hardness tester, and the 500℃ hardness was measured using a high-temperature Vickers hardness tester. The specific data are shown in Table 2.

[0066] Table 2 Hardness data of printed workpieces at room temperature and 500℃

[0067]

[0068] As can be seen from Table 1, the acid solubility of the modified titanium dioxide in Examples 1-4 is significantly lower than that of the modified titanium dioxide in Comparative Examples 1-5, indicating that the modified titanium dioxide prepared by the preparation method of the present invention forms a relatively uniform and dense coating layer, thereby reducing the photocatalytic activity of titanium dioxide and helping to improve the weather resistance of 3D printed ceramic materials.

[0069] As shown in Table 2, the mechanical strength of the modified titanium dioxide in Examples 1-4 at room temperature and high temperature is better than that of the modified titanium dioxide prepared in Comparative Examples 1-5, indicating that the modified titanium dioxide prepared by the preparation method of the present invention has excellent mechanical properties and weather resistance.

[0070] Comparing the results of Example 1 and Comparative Example 1 in Table 1-2, it can be seen that the order of organic modification and inorganic coating cannot be changed, and changing the preparation steps may lead to poor performance of the modified titanium dioxide.

[0071] By comparing the results of Example 1 and Comparative Examples 2-3 in Table 1-2, it can be seen that titanium dioxide, graphene oxide and titanate coupling agent have a synergistic effect, which can effectively improve the weather resistance of titanium dioxide and the strength, weather resistance and high temperature resistance of the corresponding workpiece.

[0072] By comparing the results of Example 1 and Comparative Examples 4-5 in Table 1-2, it can be seen that when the mass ratio of titanium dioxide, graphene oxide and titanate coupling agent is (3-5):1:1, the strength, weather resistance and high temperature resistance of the modified titanium dioxide are all at a relatively good level.

[0073] In summary, the modification of titanium dioxide by first organic modification and then inorganic coating not only effectively solves the problems existing in unmodified titanium dioxide, but also improves its application performance in 3D printing ceramic materials, enhances the overall stability and weather resistance of ceramic products, and provides strong support for the development of 3D printing ceramic technology.

[0074] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A method for preparing modified titanium dioxide, characterized in that: The following steps are involved: S1. Ultrasonic dispersion of titanium dioxide in a 75% volume concentration ethanol aqueous solution to obtain a titanium dioxide slurry, adding a titanate coupling agent and graphene oxide, and adjusting the pH of the system to 3-4 with glacial acetic acid. The mixture is heated to 85-95°C and stirred for reaction for 5-6 hours. The mixture is centrifuged, washed with water, vacuum dried, and then crushed to obtain a composite powder; wherein the titanium dioxide is nano-scale rutile titanium dioxide with a particle size of 50-300 nm, the graphene oxide is nano-scale graphene oxide with a single-layer diameter of 50-300 nm, and the mass ratio of the titanium dioxide, graphene oxide, and titanate coupling agent is (3-5):1:1; S2. Ultrasonic dispersion of the composite powder in water to obtain a composite slurry, heating the composite slurry to 80-90°C and then keeping it warm, adjusting the pH of the system to 6-6.5, adding a sodium aluminate solution for coating treatment for 1-3 hours, adjusting the pH of the composite system to 8-8.5, adding a sodium silicate solution for coating treatment for 1-3 hours, aging, filtering, washing, drying, and crushing to obtain the modified titanium dioxide.

2. The method for preparing modified titanium dioxide according to claim 1, wherein In step S1, the mass ratio of the titanium dioxide to the ethanol aqueous solution is 1:(2-3).

3. The method for preparing modified titanium dioxide according to claim 1, wherein In step S1, the ultrasonic power is 130-250 W, the ultrasonic temperature is 45-55° C., and the ultrasonic time is 0.8-1.2 h.

4. The method for preparing modified titanium dioxide according to claim 1, wherein In the step S1, the stirring reaction is carried out at a speed of 300-500 r / min; the drying temperature is 70-80° C., and the drying time is 2-3 h; and the pulverization is carried out using a jet mill to pulverize the particles to a particle size of 0.2-0.5 μm.

5. The method for preparing modified titanium dioxide according to claim 1, wherein: In step S2, the mass ratio of the composite powder to water is 1:(2-3).

6. The method for preparing modified titanium dioxide according to claim 1, wherein: In step S2, the mass concentration of the sodium aluminate solution is 10-40 g / L, and the mass ratio of the composite slurry to the sodium aluminate solution is 1:(0.1-1).

7. The method for preparing modified titanium dioxide according to claim 1, wherein: In step S2, the mass concentration of the sodium silicate solution is 20-60 g / L, and the mass ratio of the composite slurry to the sodium silicate solution is 1:(0.1-1).

8. A modified titanium dioxide, characterized in that: The modified titanium dioxide is prepared by the preparation method of any one of claims 1 to 7.

9. Use of the modified titanium dioxide according to claim 8 in the preparation of 3D printing ceramic materials.

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