Conductive titanium dioxide and its preparation method and application

Abstract

The application relates to the technical field of pigment and filler preparation, and discloses conductive titanium white powder as well as a preparation method and application thereof. The preparation method of the conductive titanium white powder comprises the following steps: step one, using ethanol tantalum, titanium tetraisopropoxide, isopropyl alcohol and ethylene glycol aqueous solution as raw materials, reacting to prepare doped modified titanium dioxide; step two, coating the doped modified titanium dioxide with an organic monomer to obtain organic modified titanium dioxide; and step three, coating the organic modified titanium dioxide with a metal oxide to obtain the conductive titanium white powder. The conductive titanium white powder has excellent conductivity and weather resistance, small particle size, easy dispersibility and good formula applicability, and can be used in conductive coatings.

Description

Technical Field

[0001] This invention relates to the field of pigment and filler preparation technology, specifically to a conductive titanium dioxide, its preparation method, and its application. Background Technology

[0002] Titanium dioxide has high whiteness, hiding power, opacity and gloss, and is recognized as one of the best inorganic white pigments in terms of application performance. It is known as the "King of Inorganic White Pigments" and can be used in many fields such as plastics, paints, water-based coatings, rubber, inks, masterbatches and decorative paper.

[0003] Currently, the preparation process of conductive coatings is relatively mature and they are widely used in static electricity elimination. Furthermore, conductive coatings have advantages such as simple operation, fewer construction steps, and lower cost. In general, the main function of titanium dioxide in conductive coatings is to improve the mechanical strength, optical properties, and rheological properties of the coating. However, titanium dioxide is relatively poor at improving the conductivity of the coating; therefore, research on conductive titanium dioxide has been proposed.

[0004] For example, Chinese patent CN111040474B discloses a conductive titanium dioxide and its preparation method, which solves the problem of poor conductivity of titanium dioxide. However, titanium dioxide has photochemical activity and poor weather resistance, and it will gradually lose its luster and covering power under light and climate change. Therefore, improving the weather resistance of titanium dioxide is also crucial. Summary of the Invention

[0005] To address the aforementioned technical problems, this invention provides a method for preparing conductive titanium dioxide, comprising the following steps:

[0006] Step 1: Using tantalum ethoxide, titanium tetraisopropoxide, isopropanol, and an aqueous solution of glycolic acid as raw materials, react to prepare doped modified titanium dioxide.

[0007] Step 2: Coating the doped and modified titanium dioxide with organic monomers to obtain organically modified titanium dioxide;

[0008] Step 3: Coat the organically modified titanium dioxide with metal oxides to obtain conductive titanium dioxide.

[0009] Preferably, in step one, the volume ratio of tantalum ethoxide, titanium tetraisopropoxide, isopropanol, and aqueous glycolic acid solution is (0.22-0.3):5:5:50; and the average particle size of the doped modified titanium dioxide is 170 nm.

[0010] Preferably, in step one, the reaction conditions are: first, stirring at 500 r / min at 78-82℃ for 1.5-2.5 h, and then hydrothermal reaction at 195-205℃ and 1.6 MPa for 5-7 h.

[0011] In the above process, using the traditional hydrothermal method, tantalum ethoxide and titanium tetraisopropoxide are used as tantalum and titanium sources, isopropanol is used as a solvent, and glycolic acid is used as an additive to promote the formation of rutile titanium dioxide, thus obtaining rutile-modified titanium dioxide containing metallic tantalum. Compared with anatase titanium dioxide, rutile titanium dioxide has better stability and better weather resistance. Furthermore, the doping of tantalum improves the conductivity of rutile titanium dioxide.

[0012] Preferably, in step two, the method for preparing the organically modified titanium dioxide specifically includes:

[0013] Doped and modified titanium dioxide was added to dimethylformamide, sonicated, and then an organic monomer was added. The mixture was stirred at 23-28℃ for 40-60 min under a nitrogen atmosphere, and then heated to 75-85℃. Ammonium persulfate was added, and the mixture was stirred for 5-7 h. After purification, organically modified titanium dioxide was obtained. The mass ratio of doped and modified titanium dioxide, dimethylformamide, organic monomer, and ammonium persulfate was (5-9):(200-300):(6.6-17.2):(0.1-0.2).

[0014] In the above process, the β-keto ester groups in the organic monomer can coordinate with the metal ions in the doped and modified titanium dioxide. Then, under the initiation of ammonium persulfate, both the carbon-carbon double bond and the thiophene moiety can undergo self-polymerization, thereby forming a dense and firm conductive organic layer on the surface of the doped and modified titanium dioxide. On the one hand, this improves the conductivity of the doped and modified titanium dioxide. On the other hand, it coats the doped and modified titanium dioxide to prevent it from agglomerating and reducing its particle size, thereby reducing the photoactivity of the doped and modified titanium dioxide and improving its conductivity, dispersibility and weather resistance.

[0015] Preferably, the organic monomer in step two is prepared by the following steps:

[0016] Step S1: Mix intermediate product A, 1-amino-3-buten-2-ol, and ethanol in a mass ratio of (2.4-3.6):(1.3-2.5):(80-100), stir until homogeneous, heat to 66-74℃, stir for 2-4 hours, purify, and obtain intermediate product B.

[0017] Step S2: Mix the thiophene compound and ethanol at a mass ratio of (2.7-4):(20-30), stir, and obtain a thiophene compound dispersion; mix intermediate product B and ethanol at a mass ratio of (4.2-6.2):(60-80), add the above thiophene compound dispersion dropwise in an ice-water bath, react at 0℃ for 2 h, then react at 23-28℃ for 3.5-4.5 h, purify, and obtain the organic monomer.

[0018] Furthermore, the intermediate product A in step S1 is prepared by the following steps:

[0019] Ethyl acetoacetate methacrylate was added to ethanol and stirred. Then 3-mercapto-2-methylpentanal and azobisisobutyronitrile were added. The mixture was heated to 60-70℃ and stirred for 3-5 hours. After purification, intermediate product A was obtained. The mass ratio of ethyl acetoacetate methacrylate, ethanol, 3-mercapto-2-methylpentanal and azobisisobutyronitrile was (2.5-4.5):(80-100):(1.3-2.6):(0.03-0.05).

[0020] Furthermore, the thiophene compound in step S2 is prepared by the following steps:

[0021] 2,5-Dicarboxylic acid-3,4-ethylenedioxythiophene and thionyl chloride were mixed in a mass ratio of (2.3-3.5):(5.9-11.8), stirred for 3-4 h, and then reacted at 76-84 °C for 20-30 min. After purification, thiophene-based compounds were obtained.

[0022] In the above process, ethyl acetoacetate methacrylate contains a β-keto ester group, which can rapidly coordinate with metal ions to form strong coordination bonds. Ethyl acetoacetate methacrylate combines with 3-mercapto-2-methyl-pentanal through the reaction between the thiol group and the carbon-carbon double bond to obtain intermediate A containing a β-keto ester group and an aldehyde group. Intermediate A combines with 1-amino-3-buten-2-ol through a Schiff base reaction to obtain intermediate B containing a β-keto ester group, a hydroxyl group, and a carbon-carbon double bond. Next, 2,5-dicarboxylic acid-3,4-ethylenedioxythiophene reacts with thionyl chloride to convert the carboxyl group of 2,5-dicarboxylic acid-3,4-ethylenedioxythiophene into an acyl chloride, forming a thiophene group compound. As is well known, thiophene group compounds can polymerize to form polythiophene with excellent electrical conductivity. Finally, the acyl chloride of the thiophene group compound reacts with the hydroxyl group of intermediate B to obtain an organic monomer. The organic monomer contains a β-keto ester group, a carbon-carbon double bond, and a thiophene group.

[0023] Preferably, in step three, the method for preparing the conductive titanium dioxide specifically includes:

[0024] Solution A is prepared by adding tin chloride pentahydrate to ethanol; solution B is prepared by adding zinc chloride and citric acid to water; solution A is added to solution B, stirred, then organically modified titanium dioxide is added, followed by 4 mol / L sodium hydroxide aqueous solution, ultrasonically treated for 1-2 hours, filtered, washed, and dried. The dried product is then calcined at 590-610℃ for 100-150 minutes in an argon atmosphere to obtain conductive titanium dioxide; wherein the mass ratio of tin chloride pentahydrate, zinc chloride, citric acid, organically modified titanium dioxide, and 4 mol / L sodium hydroxide aqueous solution is (1.4-2.8):(0.55-1.1):(0.84-1.68):(12-20):(55-110);

[0025] In the above process, tin chloride pentahydrate and zinc chloride were used as metal precursors, and citric acid was used as a reducing agent to form a zinc oxide-doped tin oxide metal oxide layer on the surface of organically modified titanium dioxide. The β-keto ester groups on the surface of organically modified titanium dioxide coordinated with zinc and tin ions, providing growth sites for the in-situ generation of zinc oxide and tin oxide. Furthermore, the strong coordination between the metal and the β-keto ester groups ensured that the metal oxide layer was firmly coated on the surface of organically modified titanium dioxide. Tin oxide in the metal oxide layer has excellent conductivity. After zinc oxide doping, not only was the conductivity of the metal oxide layer improved, but its weather resistance was also improved.

[0026] The conductive titanium dioxide prepared by the aforementioned method is described.

[0027] The application of the conductive titanium dioxide in conductive coatings.

[0028] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0029] 1. The conductive titanium dioxide of the present invention is obtained by coating an organic layer and a metal oxide layer on the surface of doped and modified titanium dioxide. It not only has excellent conductivity and weather resistance, but also has the advantages of small particle size and easy dispersion. It has good formulation applicability and can be used in conductive coatings.

[0030] 2. The presence of an organic layer in the conductive titanium dioxide of the present invention improves the conductivity of the doped and modified titanium dioxide on the one hand, and forms a dense and firm coating layer on the surface of the doped and modified titanium dioxide on the other hand, preventing its agglomeration and thus reducing the particle size and reducing the photoactivity of the doped and modified titanium dioxide, thereby improving the conductivity, dispersibility and weather resistance of the doped and modified titanium dioxide; furthermore, the presence of the organic layer provides growth sites for the coating of the metal oxide layer, improving the coating effect of the metal oxide layer.

[0031] 3. The outermost layer of the conductive titanium dioxide of the present invention is a zinc oxide-doped tin oxide metal oxide layer. Under the combined action of tin oxide and zinc oxide, the conductivity and weather resistance of the titanium dioxide are further improved.

[0032] 4. In the process of preparing doped modified titanium dioxide, the present invention uses glycolic acid as an additive to promote the formation of rutile titanium dioxide. Compared with anatase titanium dioxide, rutile titanium dioxide has better stability and better weather resistance. Furthermore, the doping of tantalum in titanium dioxide can effectively improve the conductivity of rutile titanium dioxide. Attached Figure Description

[0033] Figure 1 This is a comparison chart of the volume resistivity tests of conductive titanium dioxide prepared in Examples 2-6 and Comparative Examples 1-5 of the present invention.

[0034] Figure 2 This is a comparison chart of the methylene blue degradation rate of conductive titanium dioxide prepared in Examples 2-6 and Comparative Examples 1-5 of the present invention. Detailed Implementation

[0035] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0036] Example 1

[0037] This embodiment discloses a method for preparing an organic monomer, including the following steps:

[0038] Step S1: Add 3.5g of ethyl acetoacetate methacrylate to 90g of ethanol and stir for 15min. Then add 1.9g of 3-mercapto-2-methyl-pentanal and 0.04g of azobisisobutyronitrile. Heat to 65℃ and stir for 4h. After the reaction is complete, remove the solvent and unreacted ethyl acetoacetate methacrylate by rotary evaporation to obtain intermediate product A.

[0039] Add 3g of intermediate product A and 1.9g of 1-amino-3-buten-2-ol to 90g of ethanol, stir until homogeneous, heat to 70℃, stir and react for 3h. After the reaction is completed, remove the solvent and unreacted 1-amino-3-buten-2-ol by rotary evaporation to obtain intermediate product B.

[0040] Step S2: Mix 3g of 2,5-dicarboxylic acid-3,4-ethylenedioxythiophene with 8.9g of thionyl chloride, stir for 3.5h, then react at 80℃ for 25min, and remove excess thionyl chloride by distillation to obtain thiophene-based compound;

[0041] 3.4 g of thiophene compound was added to 25 g of ethanol and stirred for 30 min to obtain a thiophene compound dispersion. 5.2 g of intermediate product B was added to 70 g of ethanol and the above thiophene compound dispersion was added dropwise at a rate of 1.5 mL / min while stirring in an ice-water bath. The reaction was first carried out at 0 °C for 2 h, and then at 25 °C for 4 h. After the reaction was completed, the solvent was evaporated to obtain the organic monomer.

[0042] Example 2

[0043] This embodiment discloses a method for preparing conductive titanium dioxide, including the following steps:

[0044] Step 1: Tantalum ethoxide, titanium tetraisopropoxide, isopropanol, and 1.6 mol / L glycolic acid aqueous solution were mixed in a volume ratio of 0.22:5:5:50. The mixture was first stirred at 500 r / min for 2.5 h at 78 °C, and then hydrothermally reacted at 195 °C and 1.6 MPa for 7 h. After the reaction was completed, the mixture was cooled to room temperature, centrifuged, washed, and dried to obtain doped modified titanium dioxide.

[0045] Step 2: Add 5g of doped modified titanium dioxide to 200g of dimethylformamide, sonicate for 20min, then add 6.6g of organic monomer, stir at 23℃ for 60min in a nitrogen atmosphere, then heat to 75℃, add 0.1g of ammonium persulfate, stir and react for 7h. After the reaction is complete, centrifuge, wash and dry to obtain organic modified titanium dioxide.

[0046] Step 3: Add 1.4g of tin chloride pentahydrate to 24g of ethanol to prepare solution A; add 0.55g of zinc chloride and 0.84g of citric acid to 100g of water to prepare solution B; add solution A to solution B, stir for 10min, then add 12g of organically modified titanium dioxide, then add 55g of 4mol / L sodium hydroxide aqueous solution, sonicate for 1h, filter, wash, and dry. Calcine the dried product at 590℃ for 150min in an argon atmosphere to obtain conductive titanium dioxide.

[0047] Example 3

[0048] This embodiment discloses a method for preparing conductive titanium dioxide, including the following steps:

[0049] Step 1: Tantalum ethoxide, titanium tetraisopropoxide, isopropanol, and 1.6 mol / L glycolic acid aqueous solution were mixed in a volume ratio of 0.3:5:5:50. The mixture was first stirred at 82℃ and 500 r / min for 2.5 h, and then hydrothermally reacted at 205℃ and 1.6 MPa for 5 h. After the reaction was completed, the mixture was cooled to room temperature, centrifuged, washed, and dried to obtain doped modified titanium dioxide.

[0050] Step 2: Add 9g of doped modified titanium dioxide to 300g of dimethylformamide, sonicate for 40min, then add 17.2g of organic monomer, stir at 28℃ for 40min in a nitrogen atmosphere, then heat to 85℃, add 0.2g of ammonium persulfate, stir and react for 5h. After the reaction is complete, centrifuge, wash and dry to obtain organic modified titanium dioxide.

[0051] Step 3: Add 2.8g of tin chloride pentahydrate to 24g of ethanol to prepare solution A; add 1.1g of zinc chloride and 1.68g of citric acid to 100g of water to prepare solution B; add solution A to solution B, stir for 20min, then add 20g of organically modified titanium dioxide, then add 110g of 4mol / L sodium hydroxide aqueous solution, sonicate for 2h, filter, wash, and dry. Calcine the dried product at 610℃ for 100min in an argon atmosphere to obtain conductive titanium dioxide.

[0052] Example 4

[0053] This embodiment discloses a method for preparing conductive titanium dioxide, including the following steps:

[0054] Step 1: Tantalum ethoxide, titanium tetraisopropoxide, isopropanol, and 1.6 mol / L glycolic acid aqueous solution are mixed in a volume ratio of 0.26:5:5:50. The mixture is first stirred at 80℃ and 500 r / min for 2 h, and then hydrothermally reacted at 200℃ and 1.6 MPa for 6 h. After the reaction is completed, the mixture is cooled to room temperature, centrifuged, washed, and dried to obtain doped modified titanium dioxide.

[0055] Step 2: Add 7g of doped modified titanium dioxide to 250g of dimethylformamide, sonicate for 30min, then add 11.9g of organic monomer, stir at 25℃ for 50min in a nitrogen atmosphere, then heat to 80℃, add 0.15g of ammonium persulfate, stir and react for 6h. After the reaction is complete, centrifuge, wash and dry to obtain organic modified titanium dioxide.

[0056] Step 3: Add 2.1g of tin chloride pentahydrate to 24g of ethanol to prepare solution A; add 0.83g of zinc chloride and 1.26g of citric acid to 100g of water to prepare solution B; add solution A to solution B, stir for 15min, then add 16g of organically modified titanium dioxide, then add 82.5g of 4mol / L sodium hydroxide aqueous solution, sonicate for 1.5h, filter, wash, and dry. Calcine the dried product at 600℃ for 125min in an argon atmosphere to obtain conductive titanium dioxide.

[0057] Example 5

[0058] This embodiment discloses a method for preparing conductive titanium dioxide, including the following steps:

[0059] Step 1: Tantalum ethoxide, titanium tetraisopropoxide, isopropanol, and 1.6 mol / L glycolic acid aqueous solution were mixed in a volume ratio of 0.24:5:5:50. The mixture was first stirred at 79℃ and 500 r / min for 1.8 h, and then hydrothermally reacted at 198℃ and 1.6 MPa for 5.5 h. After the reaction was completed, the mixture was cooled to room temperature, centrifuged, washed, and dried to obtain doped modified titanium dioxide.

[0060] Step 2: Add 6g of doped modified titanium dioxide to 225g of dimethylformamide, sonicate for 25min, then add 9.3g of organic monomer, stir at 24℃ for 55min in a nitrogen atmosphere, then heat to 78℃, add 0.13g of ammonium persulfate, stir and react for 5.5h. After the reaction is complete, centrifuge, wash and dry to obtain organic modified titanium dioxide.

[0061] Step 3: Add 1.8g of tin chloride pentahydrate to 24g of ethanol to prepare solution A; add 0.69g of zinc chloride and 1.05g of citric acid to 100g of water to prepare solution B; add solution A to solution B, stir for 13min, then add 14g of organically modified titanium dioxide, then add 68.75g of 4mol / L sodium hydroxide aqueous solution, sonicate for 1.3h, filter, wash, and dry. Calcine the dried product at 595℃ for 135min in an argon atmosphere to obtain conductive titanium dioxide.

[0062] Example 6

[0063] This embodiment discloses a method for preparing conductive titanium dioxide, including the following steps:

[0064] Step 1: Tantalum ethoxide, titanium tetraisopropoxide, isopropanol, and 1.6 mol / L glycolic acid aqueous solution were mixed in a volume ratio of 0.28:5:5:50. The mixture was first stirred at 81℃ and 500 r / min for 2.3 h, and then hydrothermally reacted at 203℃ and 1.6 MPa for 6.5 h. After the reaction was completed, the mixture was cooled to room temperature, centrifuged, washed, and dried to obtain doped modified titanium dioxide.

[0065] Step 2: Add 8g of doped modified titanium dioxide to 275g of dimethylformamide, sonicate for 35min, then add 14.6g of organic monomer, stir at 27℃ for 55min in a nitrogen atmosphere, then heat to 83℃, add 0.18g of ammonium persulfate, stir and react for 6.5h. After the reaction is complete, centrifuge, wash and dry to obtain organic modified titanium dioxide.

[0066] Step 3: Add 2.5g of tin chloride pentahydrate to 24g of ethanol to prepare solution A; add 0.97g of zinc chloride and 1.47g of citric acid to 100g of water to prepare solution B; add solution A to solution B, stir for 15min, then add 18g of organically modified titanium dioxide, then add 96.3g of 4mol / L sodium hydroxide aqueous solution, sonicate for 1.8h, filter, wash, and dry. Calcine the dried product at 605℃ for 115min in an argon atmosphere to obtain conductive titanium dioxide.

[0067] The organic monomers used in Examples 2-6 above are the organic monomers prepared in Example 1.

[0068] Comparative Example 1

[0069] This comparative example discloses a method for preparing conductive titanium dioxide, including the following steps:

[0070] Step 1: Tantalum ethoxide, titanium tetraisopropoxide, isopropanol, and 1.6 mol / L glycolic acid aqueous solution are mixed in a volume ratio of 0.26:5:5:50. The mixture is first stirred at 80℃ and 500 r / min for 2 h, and then hydrothermally reacted at 200℃ and 1.6 MPa for 6 h. After the reaction is completed, the mixture is cooled to room temperature, centrifuged, washed, and dried to obtain doped modified titanium dioxide.

[0071] Step 2: Add 7g of doped modified titanium dioxide to 250g of dimethylformamide, sonicate for 30min, then add 11.9g of intermediate product B prepared in Example 1, stir at 25℃ for 50min in a nitrogen atmosphere, then heat to 80℃, add 0.15g of ammonium persulfate, stir for 6h, after the reaction is completed, centrifuge, wash, and dry to obtain organic modified titanium dioxide;

[0072] Step 3: Add 2.1g of tin chloride pentahydrate to 24g of ethanol to prepare solution A; add 0.83g of zinc chloride and 1.26g of citric acid to 100g of water to prepare solution B; add solution A to solution B, stir for 15min, then add 16g of organically modified titanium dioxide, then add 82.5g of 4mol / L sodium hydroxide aqueous solution, sonicate for 1.5h, filter, wash, and dry. Calcine the dried product at 600℃ for 125min in an argon atmosphere to obtain conductive titanium dioxide.

[0073] Comparative Example 2

[0074] This comparative example discloses a method for preparing conductive titanium dioxide, including the following steps:

[0075] Step 1: Tantalum ethoxide, titanium tetraisopropoxide, isopropanol, and 1.6 mol / L glycolic acid aqueous solution are mixed in a volume ratio of 0.26:5:5:50. The mixture is first stirred at 80℃ and 500 r / min for 2 h, and then hydrothermally reacted at 200℃ and 1.6 MPa for 6 h. After the reaction is completed, the mixture is cooled to room temperature, centrifuged, washed, and dried to obtain doped modified titanium dioxide.

[0076] Step 2: Add 2.1g of tin chloride pentahydrate to 24g of ethanol to prepare solution A; add 0.83g of zinc chloride and 1.26g of citric acid to 100g of water to prepare solution B; add solution A to solution B, stir for 15min, then add 16g of organically modified titanium dioxide, then add 82.5g of 4mol / L sodium hydroxide aqueous solution, sonicate for 1.5h, filter, wash, and dry. Calcine the dried product at 600℃ for 125min in an argon atmosphere to obtain conductive titanium dioxide.

[0077] Comparative Example 3

[0078] This comparative example discloses a method for preparing conductive titanium dioxide, including the following steps:

[0079] Step 1: Mix tetraisopropoxide titanium, isopropanol, and 1.6 mol / L glycolic acid in a water solution at a volume ratio of 5:5:50. First, stir at 80℃ and 500 r / min for 2 h. Then, perform a hydrothermal reaction at 200℃ and 1.6 MPa for 6 h. After the reaction is completed, cool to room temperature, centrifuge, wash, and dry to obtain nano-titanium dioxide.

[0080] Step 2: Add 7g of nano-titanium dioxide to 250g of dimethylformamide, sonicate for 30min, then add 11.9g of the organic monomer prepared in Example 1, stir at 25℃ for 50min in a nitrogen atmosphere, then raise the temperature to 80℃, add 0.15g of ammonium persulfate, stir and react for 6h. After the reaction is completed, centrifuge, wash and dry to obtain organic modified titanium dioxide.

[0081] Step 3: Add 2.1g of tin chloride pentahydrate to 24g of ethanol to prepare solution A; add 0.83g of zinc chloride and 1.26g of citric acid to 100g of water to prepare solution B; add solution A to solution B, stir for 15min, then add 16g of organically modified titanium dioxide, then add 82.5g of 4mol / L sodium hydroxide aqueous solution, sonicate for 1.5h, filter, wash, and dry. Calcine the dried product at 600℃ for 125min in an argon atmosphere to obtain conductive titanium dioxide.

[0082] Comparative Example 4

[0083] This comparative example discloses a method for preparing conductive titanium dioxide, including the following steps:

[0084] Step 1: Tantalum ethoxide, titanium tetraisopropoxide, isopropanol, and 1.6 mol / L glycolic acid aqueous solution are mixed in a volume ratio of 0.26:5:5:50. The mixture is first stirred at 80℃ and 500 r / min for 2 h, and then hydrothermally reacted at 200℃ and 1.6 MPa for 6 h. After the reaction is completed, the mixture is cooled to room temperature, centrifuged, washed, and dried to obtain doped modified titanium dioxide.

[0085] Step 2: Add 7g of doped modified titanium dioxide to 250g of dimethylformamide, sonicate for 30min, then add 11.9g of the organic monomer prepared in Example 1, stir at 25℃ for 50min in a nitrogen atmosphere, then heat to 80℃, add 0.15g of ammonium persulfate, stir for 6h, after the reaction is completed, centrifuge, wash, and dry to obtain organic modified titanium dioxide;

[0086] Step 3: Add 2.1g of tin chloride pentahydrate to 24g of ethanol to prepare solution A; add 16g of organically modified titanium dioxide to solution A, then add 82.5g of 4mol / L sodium hydroxide aqueous solution, sonicate for 1.5h, filter, wash, and dry. Calcine the dried product at 600℃ for 125min in an argon atmosphere to obtain conductive titanium dioxide.

[0087] Comparative Example 4

[0088] This comparative example discloses a method for preparing conductive titanium dioxide, including the following steps:

[0089] Step 1: Tantalum ethoxide, titanium tetraisopropoxide, isopropanol, and 1.6 mol / L glycolic acid aqueous solution are mixed in a volume ratio of 0.26:5:5:50. The mixture is first stirred at 80℃ and 500 r / min for 2 h, and then hydrothermally reacted at 200℃ and 1.6 MPa for 6 h. After the reaction is completed, the mixture is cooled to room temperature, centrifuged, washed, and dried to obtain doped modified titanium dioxide.

[0090] Step 2: Add 7g of doped modified titanium dioxide to 250g of dimethylformamide, sonicate for 30min, then add 11.9g of the organic monomer prepared in Example 1, stir at 25℃ for 50min in a nitrogen atmosphere, then raise the temperature to 80℃, add 0.15g of ammonium persulfate, stir and react for 6h. After the reaction is completed, centrifuge, wash and dry to obtain conductive titanium dioxide.

[0091] Experimental Example

[0092] I. Conductivity Test: Weigh 2.0g of the conductive titanium dioxide samples prepared in Examples 2-6 and Comparative Examples 1-5. Under a pressure of 20MPa, press the samples into powder sheets with a diameter of 0.4cm and a thickness of 0.2cm. Measure the resistance of each group of powder sheets and calculate the volume resistivity according to the following formula:

[0093] ;

[0094] In the formula, R is the resistance of the powder sheet (Ω), S is the cross-sectional area of ​​the powder sheet (cm2), and L is the height of the powder sheet (cm).

[0095] II. Weather Resistance Test: 100 mg of the conductive titanium dioxide samples prepared in Examples 2-6 and Comparative Examples 1-5 were weighed and added to 100 mL of 10 g / L methylene blue solution. The solutions were then irradiated and stirred under a UV lamp (395 nm) in a dark room. Samples were taken every 1 hour, and the methylene blue absorbance was measured at 664 nm using a UV-Vis spectrophotometer. (1-A) t The degradation rate of methylene blue after 5 hours was calculated using the formula (At = A0 / A0) (where At is the concentration of the methylene blue solution after a reaction period, and A0 is the initial concentration of the methylene blue solution). A higher methylene blue degradation rate indicates stronger photocatalytic activity and poorer weather resistance in titanium dioxide; conversely, a lower degradation rate indicates better weather resistance.

[0096] The test results are shown in Table 1:

[0097] Table 1

[0098] Volume resistivity / (Ω·cm) Degradation rate of methylene blue / % Example 2 17.6 3.53 Example 3 11.2 2.28 Example 4 14.9 2.91 Example 5 16.3 3.29 Example 6 12.7 2.65 Comparative Example 1 19.1 2.90 Comparative Example 2 27.5 3.83 Comparative Example 3 19.6 2.91 Comparative Example 4 22.2 3.66 Comparative Example 5 26.3 4.01

[0099] As can be seen from the test results in Table 1, the conductive titanium dioxide prepared in Examples 2-6 of this invention has excellent conductivity and weather resistance. The comparison between Comparative Example 1 and Example 4 shows that the presence of the thiophene structure in the organic layer of the conductive titanium dioxide has a significant impact on the conductivity of the titanium dioxide. The comparison between Comparative Example 2 and Example 4 shows that the presence of the organic layer in the conductive titanium dioxide of the present invention improves the conductivity of the doped modified titanium dioxide on the one hand, and forms a dense and firm coating layer on the surface of the doped modified titanium dioxide on the other hand, preventing its agglomeration and thus reducing the particle size and photoactivity of the doped modified titanium dioxide. Furthermore, the presence of the organic layer provides growth sites for the coating of the metal oxide layer, improving the coating effect of the metal oxide layer, thereby improving the conductivity and weather resistance of the doped modified titanium dioxide. The comparison between Comparative Example 3 and Example 4 shows that the doping of tantalum in titanium dioxide can effectively improve its conductivity. The comparison between Comparative Examples 4-5 and Example 4 shows that the combined effect of tin oxide and zinc oxide further improves the conductivity and weather resistance of the titanium dioxide.

[0100] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for preparing conductive titanium dioxide, characterized in that, Includes the following steps: Step 1: Using tantalum ethoxide, titanium tetraisopropoxide, isopropanol, and an aqueous solution of glycolic acid as raw materials, react to prepare doped modified titanium dioxide. Step 2: Coating the doped and modified titanium dioxide with organic monomers to obtain organically modified titanium dioxide; The organic monomer is prepared by the following method: Step S1: Add ethyl acetoacetate methacrylate to ethanol, stir, then add 3-mercapto-2-methylpentanal and azobisisobutyronitrile, heat to 60-70℃, stir for 3-5 h, purify to obtain intermediate product A; wherein, the mass ratio of ethyl acetoacetate methacrylate, ethanol, 3-mercapto-2-methylpentanal and azobisisobutyronitrile is (2.5-4.5):(80-100):(1.3-2.6):(0.03-0.05); Intermediate product A, 1-amino-3-buten-2-ol, and ethanol were mixed in a mass ratio of (2.4-3.6):(1.3-2.5):(80-100), stirred, heated to 66-74℃, stirred for 2-4 hours, and purified to obtain intermediate product B. Step S2: Mix 2,5-dicarboxylic acid-3,4-ethylenedioxythiophene and thionyl chloride in a mass ratio of (2.3-3.5):(5.9-11.8), stir for 3-4 h, then react at 76-84 °C for 20-30 min, purify to obtain thiophene-based compound; Thiophene group compound and ethanol were mixed at a mass ratio of (2.7-4):(20-30) and stirred to obtain a thiophene group compound dispersion. Intermediate product B and ethanol were mixed at a mass ratio of (4.2-6.2):(60-80). The above thiophene group compound dispersion was added dropwise in an ice-water bath. The reaction was first carried out at 0℃ for 2 h, and then at 23-28℃ for 3.5-4.5 h. After purification, an organic monomer was obtained. Step 3: Coat the organically modified titanium dioxide with metal oxides to obtain conductive titanium dioxide. The specific method is as follows: Solution A is prepared by adding tin chloride pentahydrate to ethanol; solution B is prepared by adding zinc chloride and citric acid to water; solution A is added to solution B, stirred, then organically modified titanium dioxide is added, followed by 4 mol / L sodium hydroxide aqueous solution, ultrasonically treated for 1-2 hours, filtered, washed, and dried. The dried product is then calcined at 590-610℃ for 100-150 minutes in an argon atmosphere to obtain conductive titanium dioxide; wherein the mass ratio of tin chloride pentahydrate, zinc chloride, citric acid, organically modified titanium dioxide, and 4 mol / L sodium hydroxide aqueous solution is (1.4-2.8):(0.55-1.1):(0.84-1.68):(12-20):(55-110).

2. The method for preparing conductive titanium dioxide according to claim 1, characterized in that, In step one, the volume ratio of tantalum ethoxide, titanium tetraisopropoxide, isopropanol, and aqueous glycolic acid solution is (0.22-0.3):5:5:50; the average particle size of the doped modified titanium dioxide is 170 nm.

3. The method for preparing conductive titanium dioxide according to claim 1, characterized in that, In step one, the reaction conditions are as follows: first, stir at 500 r / min at 78-82℃ for 1.5-2.5 h, and then perform hydrothermal reaction at 195-205℃ and 1.6 MPa for 5-7 h.

4. The method for preparing conductive titanium dioxide according to claim 1, characterized in that, In step two, the method for preparing the organically modified titanium dioxide specifically includes: Doped and modified titanium dioxide was added to dimethylformamide, sonicated, and then organic monomers were added. The mixture was stirred at 23-28℃ for 40-60 min under a nitrogen atmosphere, and then heated to 75-85℃. Ammonium persulfate was added, and the mixture was stirred for 5-7 h. After purification, organic modified titanium dioxide was obtained. The mass ratio of doped and modified titanium dioxide, dimethylformamide, organic monomers and ammonium persulfate was (5-9):(200-300):(6.6-17.2):(0.1-0.2).

5. A conductive titanium dioxide prepared by the method for preparing conductive titanium dioxide as described in any one of claims 1-4.

6. The application of the conductive titanium dioxide according to claim 5 in conductive coatings.

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