Preparation method of high-conductivity and high-thermal-conductivity flaky gallium-indium-doped AZO, flaky gallium-indium-doped AZO and composite material

Abstract

The present application relates to the technical field of electrically and thermally conductive polymer composite materials, and particularly relates to a preparation method of a high-conductivity and high-thermal-conductivity sheet-shaped gallium-indium-doped AZO, the sheet-shaped gallium-indium-doped AZO and a composite material, which comprises the following steps: (1) heating and stirring aluminum nitrate, gallium nitrate, indium nitrate, ethylene glycol, oxalic acid and PVA to obtain an aluminum sol; (2) stirring and reacting the aluminum-gallium-indium composite sol with graphene oxide and zinc acetate, and drying to obtain an aluminum-gallium-indium composite sol zinc acetate-coated graphene oxide powder; (3) calcining the above powder in a sintering furnace to obtain a sheet-shaped gallium-indium-doped AZO powder; and (4) modifying the gallium-indium-doped AZO using a prepared silane coupling agent solution to obtain a final product. The present application is simple in process, strong in operability and easy to mass-produce continuously.

Description

Technical Field

[0001] This invention relates to the field of conductive and thermally conductive polymer composite materials, and particularly to a method for preparing highly conductive and thermally conductive sheet-like gallium indium doped AZO, sheet-like gallium indium doped AZO, and composite materials thereof. Background Technology

[0002] Most polymer materials are insulating, some even excellent insulators, and can accumulate static electricity on their surfaces, causing hazards during use such as fires, damage to semiconductor devices, and dust contamination in cleanrooms. Most polymer materials also have low thermal conductivity, leading to localized overheating damage or increased power consumption. The most common solution to improve the electrical and thermal conductivity of polymer materials is to add conductive and thermally conductive additives. Metal powders, some conductive and thermally conductive ceramic powders, and conductive and thermally conductive carbon materials are common examples of such additives. The morphology of these powders has a significant impact on the electrical and thermal conductivity of the composite material. Two-dimensional sheet-like and one-dimensional linear powders with high aspect ratios are more effective than irregularly shaped powders. Metal powders have strong masking effects, and carbon materials are black or dark gray, making it difficult to prepare light-colored, non-metallic, highly conductive and thermally conductive materials using these materials. Transparent inorganic high-dimensional conductive and thermally conductive powders (irregular shapes are 0-1 dimensional, linear shapes are one-dimensional, and sheet-like shapes are two-dimensional) are the best solution, while also avoiding the corrosion problems associated with metals.

[0003] High aspect ratio and high crystal regularity are essential conditions for highly conductive and thermally conductive sheet-like AZO. Sheet-like AZO prepared by hydrothermal methods, sol-gel methods, etc., has an aspect ratio of around 10, or even lower, mainly because the growth process is three-dimensional, increasing in thickness. Using a high specific surface area graphene template allows for growth in the thickness direction. The aspect ratio can be controlled by the selection, concentration, and process conditions of graphene oxide. During sintering, the graphene oxide is ablated to obtain pure AZO with a high aspect ratio.

[0004] As a conductive and thermally conductive additive, AZO is added in relatively high amounts to polymer materials. According to first-principles analysis, the increase in thermal conductivity is proportional to the volume fraction of the powder, and the same applies to electrical conductivity. Excessive powder addition has a great impact on the mechanical properties of polymer materials. This is because AZO is incompatible with the interface of polymer materials and there are no chemical bonds connecting them. Therefore, it is necessary to modify the surface of the powder to increase its compatibility with polymer materials. Summary of the Invention

[0005] This invention provides a low-cost, mass-producible method for preparing highly conductive and thermally conductive sheet-like AZO. To achieve the above objective, this invention employs the following steps to prepare highly conductive and thermally conductive sheet-like AZO powder. The specific scheme is as follows:

[0006] This application provides a method for preparing highly conductive and thermally conductive sheet-like gallium indium-doped AZO, comprising the following steps:

[0007] a) Using graphene oxide as a template for synthesis, it was dispersed in deionized water and dispersed under high energy and high shear to obtain a uniformly dispersed graphene oxide slurry.

[0008] b) Dissolve soluble zinc acetate dihydrate, aluminum nitrate nonahydrate, gallium nitrate, indium nitrate, oxalic acid and PVA in deionized water to obtain the corresponding salt solution, acid solution and polymer solution. Stir and mix silane coupling agent, deionized water, acetic acid and ethanol to form silane coupling agent reaction solution.

[0009] c) Add aqueous solutions of aluminum nitrate, gallium nitrate, and indium nitrate into a heating vessel, add oxalic acid solution, heat to 50-70°C, and react for 12-24 hours to form a viscous solution;

[0010] d) Continue stirring the liquid in the heating vessel, then add ethylene glycol and PVA solution to the heating vessel, and react for another 5 to 10 hours at the same temperature;

[0011] e) Continuously stir the liquid in the heating vessel, raise the temperature to 90-110°C, dehydrate, and obtain a highly viscous aluminum gallium indium sol;

[0012] f) Pump the graphene oxide slurry into an acid- and alkali-resistant reactor, or add deionized water and graphene oxide powder directly into the reactor. After stirring evenly, disperse the graphene oxide using a high-speed emulsifier at the bottom to obtain a uniform graphene oxide slurry. Then add zinc acetate solution and stir evenly. Add the aluminum gallium indium sol and stir evenly to obtain a composite slurry. The viscosity of the composite slurry is 0.1 to 2 Pa·s.

[0013] g) The composite slurry is dried by spraying to obtain aluminum gallium indium sol and zinc acetate composite coated graphene oxide powder;

[0014] h) Gallium indium doped AZO powder was obtained by sintering the aluminum gallium indium sol prepared in step g) and zinc acetate composite-coated graphene oxide powder in a continuous tunnel sintering furnace. The temperature at the inlet of the tunnel sintering furnace was 200-300℃, the temperature in the middle section was 400-500℃, and the temperature at the high-temperature outlet was 500-600℃.

[0015] i) The sintered gallium indium doped AZO powder is ground and pulverized using a heated vertical stirred mill. The silane coupling agent reaction solution is sprayed into the vertical stirred mill, and the milling and stirring are continued until the silane coupling agent reaction solution is uniformly coated on the surface of the powder. The milling and stirring are continued and the temperature is increased. The drying temperature is 80-120℃ to obtain silane coupling agent modified plate-shaped gallium indium doped AZO.

[0016] Optionally, the preparation steps a) to i) adopt a continuous production line, which includes a jacketed stainless steel reactor with dual dispersion and stirring, a spray drying tower, a continuous sintering furnace, a vertical stirred mill, a reaction liquid preparation tank, a slurry transfer pump, and a conveyor belt.

[0017] Optionally, in step a), the specific surface area of ​​the graphene oxide is 500-1500 m² / g, the particle size is 0.5-50 micrometers, the oxygen content is 20-40%, the weight percentage concentration of the graphene oxide slurry is 1-10%, and the viscosity is 2-20 Pa·s.

[0018] Optionally, in step b), the concentration of aluminum nitrate nonahydrate is 0.01–0.5 mol / L, the concentration of gallium nitrate is 0.01–0.2 mol / L, the concentration of indium nitrate is 0.01–0.2 mol / L, the concentration of zinc acetate dihydrate is 0.2–2 mol / L, the concentration of oxalic acid is 1–2 mol / L, the concentration of PVA is 5–15%, and the weight ratio of the silane coupling agent reaction solution is ethanol:silane coupling agent:deionized water:acetic acid 100:3–15:5–30:1–3.

[0019] In steps e) and f), the molar ratio of each component in the aluminum gallium indium sol is 1:2-3.5:1.5-2.5 for aluminum:oxalic acid:ethylene glycol, the weight ratio of ethylene glycol:PVA is 100:10-50, and the molar ratio of zinc:aluminum:gallium:indium is 1:0.03-0.07:0.001-0.02:0.001-0.02.

[0020] Select the appropriate silane according to the polymer material. For epoxy systems, use epoxy-terminated or amino-terminated silanes. For organosilicon resins, use vinyl silanes. For polyurethanes, use amino silanes. Prepare the salt solutions, alkali solutions and silane coupling agent reaction solutions in reaction vessels resistant to acids, alkalis and ethanol.

[0021] Optionally, in step f), the acid and alkali resistant reactor is a jacketed stainless steel reactor with dual dispersion and stirring, with a zinc acetate solution inlet and an aluminum gallium indium sol inlet at the top, and a solid graphene oxide powder feed inlet at the top; the top-driven stirring paddle is a frame type with scrapers to stir high-viscosity slurry, and the bottom-driven high-speed emulsifying head can achieve a shear rate of over 10 m / s to disperse the agglomerated graphene oxide; it is equipped with a temperature sensor and a pH sensor, and has a temperature control range of 20–95°C.

[0022] Optionally, in step g), the composite slurry is dried by high-pressure spray at a pressure of 2-5 MPa. After being pressurized by a high-pressure pump, the slurry passes through a preheater to raise its temperature to between 150-250°C. The temperature of the drying hot air inside the tower is 120-150°C.

[0023] Optionally, in step i), a heatable vertical stirred mill is used, filled with glass beads at 15-30% of its effective volume, with a maximum heating temperature of 150°C. A coupling agent reaction liquid atomizing nozzle is fixed on the top cover, and the liquid pressure is 0.5-1.5 MPa. First, sintered AZO powder is filled in and stirred rapidly. The agglomeration of the powder is broken up by the grinding action of the glass beads. Then, the silane coupling agent reaction liquid is sprayed while stirring. After spraying, stirring is continued until the liquid is evenly dispersed in the powder. Then, the temperature is raised to between 80-120°C until the moisture content is below 1%.

[0024] Optionally, a continuous production device is used for preparation. The device includes a jacketed stainless steel reactor with dual dispersion and stirring, a spray drying tower, a continuous sintering furnace, a vertical stirred mill, and packaging equipment, which are connected in sequence by liquid and slurry transfer pumps and conveyor belts. The liquid raw materials are quantitatively introduced into the reactor from the reaction liquid preparation tank through a metering pump. The graphene oxide powder is added to the reactor manually. The filter cake is returned to the reactor through a conveyor belt.

[0025] This application also provides a highly conductive and thermally conductive sheet-like gallium indium doped AZO, wherein the sheet-like morphology of the highly conductive and thermally conductive sheet-like gallium indium doped AZO has an aspect ratio greater than 20 and an average particle size greater than 2 micrometers.

[0026] This application also provides a polymer composite material prepared using the above-mentioned sheet-like gallium indium doped AZO powder. The thermal and electrical conductivity of the polymer composite material is more than twice that of a composite material made using irregularly shaped gallium indium doped AZO powder with the same volume content.

[0027] This invention uses graphene oxide as a template, aluminum nitrate, gallium nitrate, indium nitrate, and zinc acetate as raw materials, and is supported by aluminum, gallium, and indium composite sol preparation technology, coating technology, and silane coupling agent modification technology to prepare a sheet-like gallium indium doped AZO powder. All production equipment is industrial-scale continuous production equipment. The process begins by adding oxalic acid dropwise to aluminum nitrate, gallium nitrate, and indium nitrate as raw materials, heating and stirring in a reaction vessel to form a sol, which is then mixed with ethanol and PVA to obtain a viscous aluminum gallium indium composite sol. Graphene slurry, zinc acetate, and the aluminum gallium indium composite sol are then stirred evenly and dried to obtain aluminum gallium indium composite sol zinc acetate-coated graphene oxide powder. In this process, the proportions of various raw materials, reaction temperature, and time are crucial technical parameters. After obtaining the aluminum gallium indium composite sol zinc acetate-coated graphene oxide powder, the powder is sintered in a sintering furnace, where the graphene oxide, acting as a template, is burned off, yielding sheet-like gallium indium doped AZO powder. To adapt the lamellar gallium-indium-doped AZO powder to coupling with different polymer materials, silane coupling agents are used to modify the gallium-indium-doped AZO powder. Different coupling agents are selected according to the polymer material: epoxy-terminated or amino-terminated silanes are used for epoxy systems, vinyl silanes are used for organosilicon resins, amino silanes can be used for polyurethanes, and alkyl silanes can be used for non-polar plastics. This invention provides a simple and feasible continuous production technology for lamellar gallium-indium-doped AZO powder, with a simple and efficient process. The innovation of this invention lies in the development of a simple and efficient production process that enables large-scale continuous production of lamellar gallium-indium-doped AZO powder; furthermore, the gallium-indium-doped AZO powder prepared by this method exhibits excellent electrical and thermal conductivity, and has broad application prospects. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of the continuous production line of the present invention.

[0029] The attached diagram is labeled as follows: heating kettle 1, aluminum nitrate, gallium nitrate and indium nitrate mixed solution storage tank 1-1, PVA solution storage tank 1-2, ethylene glycol storage tank 1-3, oxalic acid solution storage tank 1-4, dual dispersion heating kettle 2, zinc acetate solution storage tank 2-1, spray drying tower 3, high pressure pump 3-1, preheater 3-2, continuous sintering furnace 4, stirred mill 5, coupling agent reaction solution storage tank 5-1. Detailed Implementation

[0030] The present invention will be further described below with reference to embodiments.

[0031] Example 1

[0032] A method for preparing highly conductive and thermally conductive sheet-like gallium indium-doped AZO specifically includes the following steps:

[0033] a) Using graphene oxide as a template for synthesis, it was dispersed in deionized water and dispersed under high energy and high shear to obtain a uniformly dispersed graphene oxide slurry.

[0034] b) Dissolve soluble zinc acetate dihydrate, aluminum nitrate nonahydrate, gallium nitrate, indium nitrate, oxalic acid and PVA in deionized water to obtain the corresponding salt solution, acid solution and polymer solution. Stir and mix silane coupling agent, deionized water, acetic acid and ethanol to form silane coupling agent reaction solution.

[0035] c) Add aqueous solutions of aluminum nitrate, gallium nitrate, and indium nitrate into a heating vessel, add oxalic acid solution, heat to 50-70°C, and react for 12-24 hours to form a viscous solution;

[0036] d) Continue stirring the liquid in the heating vessel, then add ethylene glycol and PVA solution to the heating vessel, and react for another 5 to 10 hours at the same temperature;

[0037] e) Continuously stir the liquid in the heating vessel, raise the temperature to 90-110°C, dehydrate, and obtain a highly viscous aluminum gallium indium sol;

[0038] f) Pump the graphene oxide slurry into an acid- and alkali-resistant reactor, or add deionized water and graphene oxide powder directly into the reactor. After stirring evenly, disperse the graphene oxide using a high-speed emulsifier at the bottom to obtain a uniform graphene oxide slurry. Then add zinc acetate solution and stir evenly. Add the aluminum gallium indium sol and stir evenly to obtain a composite slurry. The viscosity of the composite slurry is 0.1 to 2 Pa·s.

[0039] g) The composite slurry is dried by spraying to obtain aluminum gallium indium sol and zinc acetate composite coated graphene oxide powder;

[0040] h) Gallium indium doped AZO powder was obtained by sintering the aluminum gallium indium sol prepared in step g) and zinc acetate composite-coated graphene oxide powder in a continuous tunnel sintering furnace. The temperature at the inlet of the tunnel sintering furnace was 200-300℃, the temperature in the middle section was 400-500℃, and the temperature at the high-temperature outlet was 500-600℃.

[0041] i) The sintered gallium indium doped AZO powder is ground and pulverized using a heated vertical stirred mill. The silane coupling agent reaction solution is sprayed into the vertical stirred mill, and the milling and stirring are continued until the silane coupling agent reaction solution is uniformly coated on the surface of the powder. The milling and stirring are continued and the temperature is increased. The drying temperature is 80-120℃ to obtain silane coupling agent modified plate-shaped gallium indium doped AZO.

[0042] j) Preparation steps a to i) can be carried out using a continuous production line to improve production efficiency. The production line includes a jacketed stainless steel reactor with dual dispersion and stirring, a spray drying tower, a continuous sintering furnace, a vertical stirred mill, a reaction liquid preparation tank, a slurry transfer pump, a conveyor belt, etc.

[0043] Optionally, the length-to-thickness ratio of the flake-like morphology is greater than 20, preferably greater than 30; the average particle size is greater than 2 micrometers, preferably greater than 7 micrometers.

[0044] Optionally, in step a), the graphene oxide has a specific surface area of ​​500–1500 m² / g, a particle size of 0.5–50 micrometers, and an oxygen content of 20–40%, preferably a specific surface area of ​​800–1200 m² / g, an average particle size of 2–20 micrometers, an oxygen content of 25–30%, a slurry weight percentage concentration of 1–10%, and a viscosity of 2–20 Pa·s.

[0045] Optionally, in step b), the concentration of aluminum nitrate nonahydrate is 0.01–0.5 mol / L, the concentration of gallium nitrate is 0.01–0.2 mol / L, the concentration of indium nitrate is 0.01–0.2 mol / L, the concentration of zinc acetate dihydrate is 0.2–2 mol / L, the concentration of oxalic acid is 1–2 mol / L, and the concentration of PVA is 5–15%; the molar ratio of each component in the sol is aluminum:oxalic acid:ethylene glycol 1:2–3.5:1.5–2.5, the weight ratio of ethylene glycol:PVA is 100:10–50, and the molar ratio of zinc:aluminum:gallium:indium is 1:0.03–0.07:0.001–0.02:0.001–0.02. .02; The weight ratio of the silane coupling agent reaction solution is ethanol:silane coupling agent:deionized water:acetic acid 100:3~15:5~30:1~3. The appropriate silane is selected according to the polymer material. For epoxy systems, epoxy-terminated or amino-terminated silanes are used. For organosilicon resins, vinyl silanes are used. For polyurethanes, amino silanes can be used. For non-polar plastics, alkyl silanes can be used, etc. The reaction tanks resistant to acids, alkalis and ethanol are used to prepare the various salt solutions, alkali solutions and silane coupling agent reaction solutions. For example, a polypropylene reaction tank with a stirring paddle covered with polytetrafluoroethylene is selected.

[0046] Optionally, in step f), a jacketed stainless steel reactor with dual dispersion and stirring is used. The reactor has a zinc acetate solution inlet and an aluminum gallium indium sol inlet at the top, as well as a solid graphene oxide powder feed inlet at the top. The top-driven stirring paddle is a gantry type with scrapers to stir the high-viscosity slurry, and the bottom-driven high-speed emulsifying head can achieve a shear rate higher than 10 m / s to disperse the agglomerated graphene oxide. The reactor is equipped with a temperature sensor and a pH sensor, and has a temperature control range of 20–95°C. The weight ratio of each component is 100:1–8:3–10 for zinc oxide:aluminum oxide / gallium oxide / indium oxide:graphene.

[0047] Optionally, in step g), the spray drying adopts high-pressure spray with a pressure of 2 to 5 MPa. After the slurry is pressurized by a high-pressure pump, it passes through a preheater to raise the temperature of the slurry to between 150 and 250°C. The temperature of the drying hot air in the tower is 120 to 150°C.

[0048] Optionally, in step i), a heatable vertical stirred mill is used, filled with glass beads at 15-30% of its effective volume, with a maximum heating temperature of 150°C. A coupling agent reaction liquid atomizing nozzle is fixed on the top cover, and the liquid pressure is 0.5-1.5 MPa. First, sintered AZO powder is filled in and stirred rapidly. The agglomeration of the powder is broken up by the grinding action of the glass beads. Then, the silane coupling agent reaction liquid is sprayed while stirring. After spraying, stirring is continued until the liquid is evenly dispersed in the powder. Then, the temperature is raised to between 80-120°C until the moisture content is below 1%.

[0049] Optionally, in step n), the product is obtained using a continuous production device. The device includes a jacketed stainless steel reactor with dual dispersion and stirring, a spray drying tower, a continuous sintering furnace, a vertical stirred mill, and packaging equipment, which are connected in sequence via liquid and slurry conveying pumps, conveyor belts, etc. The liquid raw materials in the reactor are quantitatively introduced from the reaction liquid preparation tank through a metering pump. The graphene powder is added manually to the reactor. The filter cake is returned to the reactor via a conveyor belt.

[0050] Optionally, the thermal and electrical conductivity of polymer composites prepared using sheet-like gallium indium doped AZO powder is more than twice that of composites prepared using irregularly shaped gallium indium doped AZO powder with the same volume content.

[0051] In one specific embodiment, the present invention provides a low-cost, mass-producible method for preparing highly conductive and thermally conductive sheet-like AZO. To achieve the above objective, the present invention employs the following steps to prepare highly conductive and thermally conductive sheet-like AZO powder:

[0052] 1) Preparation of aluminum, gallium, and indium composite sol;

[0053] 2) Preparation of aluminum, gallium and indium composite sol and zinc acetate-coated graphene oxide powder;

[0054] 3) Calcination yields sheet-like gallium indium-doped AZO powder;

[0055] 4) The final product is obtained by modification with silane coupling agent.

[0056] This invention uses graphene oxide as a template, aluminum nitrate, gallium nitrate, indium nitrate, and zinc acetate as raw materials, and is supported by aluminum, gallium, and indium composite sol preparation technology, coating technology, and silane coupling agent modification technology to prepare a sheet-like gallium indium doped AZO powder. All production equipment is industrial-scale continuous production equipment. The process begins by adding oxalic acid dropwise to aluminum nitrate, gallium nitrate, and indium nitrate as raw materials, heating and stirring in a reaction vessel to form a sol, which is then mixed with ethanol and PVA to obtain a viscous aluminum gallium indium composite sol. Graphene slurry, zinc acetate, and the aluminum gallium indium composite sol are then stirred evenly and dried to obtain aluminum gallium indium composite sol zinc acetate-coated graphene oxide powder. In this process, the proportions of various raw materials, reaction temperature, and time are crucial technical parameters. After obtaining the aluminum gallium indium composite sol zinc acetate-coated graphene oxide powder, the powder is sintered in a sintering furnace, where the graphene oxide, acting as a template, is burned off, yielding sheet-like gallium indium doped AZO powder. To adapt the lamellar gallium-indium-doped AZO powder to coupling with different polymer materials, silane coupling agents are used to modify the gallium-indium-doped AZO powder. Different coupling agents are selected according to the polymer material: epoxy-terminated or amino-terminated silanes are used for epoxy systems, vinyl silanes are used for organosilicon resins, amino silanes can be used for polyurethanes, and alkyl silanes can be used for non-polar plastics. This invention provides a simple and feasible continuous production technology for lamellar gallium-indium-doped AZO powder, with a simple and efficient process. The innovation of this invention lies in the development of a simple and efficient production process that enables large-scale continuous production of lamellar gallium-indium-doped AZO powder; furthermore, the gallium-indium-doped AZO powder prepared by this method exhibits excellent electrical and thermal conductivity, and has broad application prospects.

[0057] Example 2

[0058] The present invention will be further described below with reference to the embodiments and accompanying drawings.

[0059] Unless otherwise specified, the raw materials and equipment used in this invention are all commonly used in the field; unless otherwise specified, the methods used in this invention are all conventional methods in the field.

[0060] General Implementation Case

[0061] A schematic diagram of the device used in this invention is shown below. Figure 1 As shown. The continuous production line includes a heating kettle 1, a mixed solution storage tank of aluminum nitrate, gallium nitrate and indium nitrate 1-1, a PVA solution storage tank 1-2, an ethylene glycol storage tank 1-3, an oxalic acid solution storage tank 1-4, a dual dispersion heating kettle 2, a zinc acetate solution storage tank 2-1, a spray drying tower 3, a high-pressure pump 3-1, a preheater 3-2, a continuous sintering furnace 4, a stirred mill 5, and a coupling agent reaction solution storage tank 5-1.

[0062] According to the process flow, the materials in mixed salt solution 1-1 and oxalic acid 1-4 are added to heating vessel 1 in proportion and heated to 50-70℃. The mixture is stirred and reacted for 12-24 hours to obtain a viscous solution. Then, PVA and ethylene glycol from 1-2 and 1-3 are added to reaction vessel 1 and stirred and reacted at the same temperature for 5-10 hours. The temperature of the reaction vessel is further increased to 90-100℃ to dehydrate and obtain a viscous aluminum sol.

[0063] Graphene oxide was dispersed in deionized water and stirred at high speed to obtain a uniformly dispersed graphene oxide slurry. This graphene slurry and zinc acetate from step 2-1 were added to reaction vessel 2 and stirred evenly. Then, the aluminum gallium indium composite sol prepared in the previous step was added and stirred evenly to obtain a uniform slurry. The slurry was then spray-dried through a high-pressure pump 3-1, a preheater 3-2, and a drying tower 3 to obtain aluminum gallium indium composite sol zinc acetate coated graphene oxide powder.

[0064] The obtained powder was calcined in a continuous tunnel sintering furnace. The inlet temperature of the sintering furnace was controlled at 200-300℃, the middle section temperature at 400-500℃, and the rear section temperature at 500-600℃. After calcination, plate-shaped gallium indium doped AZO powder was obtained.

[0065] The obtained flake-shaped gallium indium doped AZO powder was added to stirred mill 5 via a conveyor belt and then stirred, ground, and pulverized. The silane coupling agent solution from step 5-1 was added to stirred mill 5 to uniformly coat the powder surface. Finally, the powder was heated to 80-120℃ and dried to obtain the final product: silane coupling agent modified flake-shaped gallium indium doped AZO powder.

[0066] The obtained gallium indium-doped AZO powder was added to different polymer materials as a conductive and thermally conductive additive, and its electrical and thermal conductivity was tested. The results showed that the electrical and thermal conductivity were significantly improved.

[0067] Example 1

[0068] (1) Aluminum nitrate, gallium nitrate, indium nitrate, and oxalic acid were added to a reaction vessel in a molar ratio of 1:2. The molar ratio of aluminum nitrate, gallium nitrate, and indium nitrate was 1:0.01–0.3:0.01–0.3. The mixture was heated to 60°C and stirred for 12 hours to obtain a viscous solution. Ethylene glycol and 10% PVA solution were added with continued stirring. The weight ratio of ethylene glycol to PVA was 5:0.5–2. In this mixed solution, the molar ratio of aluminum nitrate, gallium nitrate, indium nitrate, oxalic acid, and ethylene glycol was 1:2:2. The reaction was continued at 60°C for 10 hours, and then stirred until 100°C to dehydrate, yielding an aluminum gallium indium composite sol with a viscosity of 10–30 Pa·s.

[0069] (2) Graphene oxide and zinc acetate were added to a reaction vessel and stirred. Then, aluminum gallium indium sol was added and stirred until homogeneous. The molar ratio of Zn to Al+Ga+In was 1:0.02-0.05. After spray drying, graphene oxide powder coated with zinc aluminum acetate was obtained. During this process, the high-pressure spray was controlled at 5 MPa and the drying temperature was 200℃.

[0070] (3) The graphene oxide powder coated with zinc acetate composite aluminum gallium indium was sintered in a sintering furnace to obtain sheet-like gallium indium doped AZO powder. The inlet temperature of the sintering furnace was 300℃, the middle section temperature was 500℃, and the rear section temperature was 600℃.

[0071] (4) Prepare a silane coupling agent solution with a weight ratio of ethanol, epoxy-terminated silane, deionized water, and acetic acid of 100:5~15:10~30:1~3. Grind the flake-shaped gallium-indium-doped AZO powder in a stirred mill, and then add the coupling modification solution. The powder-to-solution mass ratio is 10:1, until the powder surface is coated with the coupling agent modification solution. Heat to 100℃ and dry to obtain silane coupling agent-modified flake-shaped gallium-indium-doped AZO powder.

[0072] (5) Add epoxy resin at a volume content of 10%, resulting in a coating thickness of 40 micrometers and a surface sheet resistance of less than 10. 6 Oh, the same volume of aluminum powder 10 7 Europe.

[0073] Example 2

[0074] (1) Aluminum nitrate, gallium nitrate, indium nitrate, and oxalic acid were added to a reaction vessel at a molar ratio of 1:2.5. The molar ratio of aluminum nitrate, gallium nitrate, and indium nitrate was 1:0.01–0.3:0.01–0.3. The mixture was heated to 60°C and stirred for 12 hours to obtain a viscous solution. Ethylene glycol and 10% PVA solution were added with continued stirring. The weight ratio of ethylene glycol to PVA was 10:0.3–4. In this mixed solution, the molar ratio of aluminum nitrate, gallium nitrate, indium nitrate, oxalic acid, and ethylene glycol was 1:2.5:2.5. The reaction was continued at 60°C for 10 hours, and then stirred until 100°C to dehydrate, yielding an aluminum gallium indium composite sol with a viscosity of 10–30 Pa·s.

[0075] (2) Graphene oxide and zinc acetate were added to a reaction vessel and stirred, followed by the addition of aluminum sol and stirring until homogeneous. The molar ratio of Zn to Al + Ga + In was 1:0.03–0.06. After spray drying, graphene oxide powder coated with aluminum gallium indium sol and zinc acetate was obtained. During this process, the high-pressure spray was controlled at 5 MPa and the drying temperature was 200 °C.

[0076] (3) Graphene oxide powder coated with zinc acetate in an aluminum gallium indium composite sol was sintered in a sintering furnace to obtain sheet-like AZO powder. The inlet temperature of the sintering furnace was 300℃, the middle section temperature was 500℃, and the rear section temperature was 600℃.

[0077] (4) Prepare a silane coupling agent solution with a weight ratio of ethanol, silane coupling agent, deionized water, and acetic acid of 100:5~15:10~30:1~5. Grind the flake-shaped gallium indium doped AZO powder in a stirred mill, and then add the coupling modification solution. The powder-to-solution mass ratio is 20:1, until the powder surface is coated with the coupling agent modification solution. Heat to 100℃ and dry to obtain silane coupling agent modified flake-shaped gallium indium doped AZO powder.

[0078] (5) Adding 15% by mass of gallium-indium-doped AZO powder to PE reduced the resistivity of the material from 2x10⁻⁶ to 2x10⁻⁶. 12 Ωm decreased to 6.7 x 10 6 Ωm.

[0079] Example 3

[0080] (1) Aluminum nitrate, gallium nitrate, indium nitrate, and oxalic acid were added to a reaction vessel in a molar ratio of 1:3. The molar ratio of aluminum nitrate, gallium nitrate, and indium nitrate was 1:0.01–0.3:0.01–0.3. The mixture was heated to 60°C and stirred for 12 hours to obtain a viscous solution. Ethylene glycol and 10% PVA solution were added with continued stirring. The weight ratio of ethylene glycol to PVA was 2:0.5–3. In this mixed solution, the molar ratio of aluminum nitrate, gallium nitrate, indium nitrate, oxalic acid, and ethylene glycol was 1:3:3. The reaction was continued at 60°C for 10 hours, and then stirred until 100°C to dehydrate and obtain aluminum sol.

[0081] (2) Graphene oxide and zinc acetate were added to a reaction vessel and stirred, followed by the addition of aluminum sol and stirring until homogeneous. The molar ratio of Zn to Al was 1:0.07. The mixture was then spray-dried to obtain graphene oxide powder coated with zinc aluminum acetate. During this process, the high-pressure spray was controlled at 5 MPa and the drying temperature was 200 °C.

[0082] (3) Gallium-indium composite sol-coated zinc acetate graphene oxide powder was sintered in a sintering furnace to obtain sheet-like gallium-indium doped AZO powder. The inlet temperature of the sintering furnace was 300℃, the middle section temperature was 500℃, and the rear section temperature was 600℃.

[0083] (4) Prepare a silane coupling agent solution with a weight ratio of ethanol, silane coupling agent, deionized water, and acetic acid of 100:5~15:10~30:1~3. Grind the flake-shaped gallium indium doped AZO powder in a stirred mill and add the coupling modification solution. The mass ratio of powder to solution is 5:1 until the powder surface is coated with the coupling agent modification solution. Then heat to 100℃ and dry to obtain silane coupling agent modified flake-shaped gallium indium doped AZO powder.

[0084] (5) Adding 20% ​​by mass of gallium indium doped AZO powder to PVC material increases its thermal conductivity by 100%.

[0085] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Any simple modifications, alterations, and equivalent transformations made to the above embodiments based on the technical essence of the present invention shall still fall within the protection scope of the present invention.

Claims

1. A method for preparing a high conductive and heat conductive sheet-shaped gallium-indium-doped AZO, characterized by, The method comprises the following steps: a) using graphene oxide as a synthesis template, dispersing it in deionized water, and obtaining a uniformly dispersed graphene oxide slurry through high-energy and high-shear dispersion; b) dissolving soluble zinc dihydrate acetate, aluminum nitrate nonahydrate, gallium nitrate, indium nitrate, oxalic acid, and PVA in deionized water to obtain corresponding salt solutions, acid solutions, and polymer solutions, and stirring and mixing silane coupling agent, deionized water, acetic acid, and ethanol into a silane coupling agent reaction solution; c) adding aluminum nitrate, gallium nitrate, and indium nitrate aqueous solutions into a heating kettle, adding an oxalic acid solution, heating to 50-70 ℃, and reacting for 12-24 hours to form a viscous solution; d) continuously stirring the liquid in the heating kettle, adding ethylene glycol and a PVA solution into the heating kettle, and reacting for another 5-10 hours at the same temperature; e) continuously stirring the liquid in the heating kettle, heating to 90-110 ℃, and dehydrating to obtain a highly viscous aluminum gallium indium sol; f) pumping the graphene oxide slurry into an acid and alkali resistant reaction kettle, or directly adding deionized water and graphene oxide powder into the reaction kettle, stirring uniformly, dispersing the graphene oxide using a high-speed emulsifier at the bottom to obtain a uniformly dispersed graphene oxide slurry, then adding zinc acetate solution, stirring uniformly, adding the aluminum gallium indium sol, stirring uniformly, and obtaining a composite slurry, wherein the viscosity of the composite slurry is 0.1-2 Pa·s; g) drying the composite slurry by spraying to obtain aluminum gallium indium sol and zinc acetate composite coated graphene oxide powder; h) using a continuous tunnel type sintering furnace to sinter the aluminum gallium indium sol and zinc acetate composite coated graphene oxide powder prepared in step g) to obtain gallium indium doped AZO powder, wherein the temperature at the inlet end of the tunnel type sintering furnace is 200-300 ℃, the temperature at the middle section is 400-500 ℃, and the temperature at the high temperature end of the outlet is 500-600 ℃; i) grinding the sintered gallium indium doped AZO powder using a heatable vertical stirring mill, spraying the silane coupling agent reaction solution into the vertical stirring mill, and continuing to stir and grind until the silane coupling agent reaction solution is uniformly coated on the surface of the powder, continuously stirring and heating, and drying at a temperature of 80-120 ℃ to obtain silane coupling agent modified sheet-shaped gallium indium doped AZO.

2. The method for preparing highly conductive and thermally conductive sheet-like gallium indium-doped AZO as described in claim 1, characterized in that, The preparation steps a)-i) are performed using a continuous production line, which comprises a jacketed stainless steel reaction kettle with double dispersion and stirring, a spray drying tower, a continuous sintering furnace, a vertical stirring mill, a reaction solution preparation tank, a slurry conveying pump, and a conveying belt.

3. The method for preparing highly conductive and thermally conductive sheet-like gallium indium-doped AZO as described in claim 1, characterized in that, In step a), the specific surface area of the graphene oxide is 500-1500 m 2 / g, the particle size is 0.5-50 microns, the oxygen content is 20-40%, the weight percentage concentration of the graphene oxide slurry is 1-10%, and the viscosity is 2-20 Pa·s.

4. The method for preparing highly conductive and thermally conductive sheet-like gallium indium-doped AZO as described in claim 1, characterized in that, In step b), the concentration of the aluminum nitrate nonahydrate is 0.01-0.5 mol / l, the concentration of the gallium nitrate is 0.01-0.2 mol / l, the concentration of the indium nitrate is 0.01-0.2 mol / l, the concentration of the zinc dihydrate acetate is 0.2-2 mol / l, the concentration of the oxalic acid is 1-2 mol / l, the concentration of the PVA is 5-15%, and the weight ratio of the silane coupling agent reaction solution is ethanol:silane coupling agent:deionized water:acetic acid is 100:3-15:5-30:1-3. In step e) and step f), the molar ratio of the components of the aluminum gallium indium sol is aluminum: oxalic acid: ethylene glycol is 1:2-3.5:1.5-2.5, the weight ratio of ethylene glycol:PVA is 100:10-50, and the molar ratio of zinc: aluminum: gallium: indium is 1:0.03-0.07:0.001-0.02:0.001-0.02; According to the selection of the polymer material, the corresponding silane is selected, the epoxy system adopts epoxy end group or amine group end group silane, the organic silicon resin selects vinyl silane, and the polyurethane selects amine group silane; an acid and alkali resistant and ethanol resistant reaction tank is used to prepare each salt solution, alkali solution and silane coupling agent reaction liquid.

5. The method for preparing highly conductive and thermally conductive sheet-like gallium indium-doped AZO as described in claim 1, characterized in that, In step f), the acid and alkali resistant reaction kettle adopts a jacketed stainless steel reaction kettle with double dispersion and stirring, the top has a zinc acetate solution inlet and an aluminum gallium indium sol inlet, and the top has a solid graphene oxide powder feeding port; the top driven stirring paddle adopts a door frame type with a scraper to stir high viscosity slurry, and the bottom driven high speed emulsifying head can realize a shear speed higher than 10 m / s to disperse the agglomerated graphene oxide; a temperature sensor and a pH sensor are provided, and the temperature control range is 20-95℃.

6. The method for preparing highly conductive and thermally conductive sheet-like gallium indium-doped AZO as described in claim 1, characterized in that, In step g), the composite slurry is dried by high pressure spraying, the pressure is 2-5 MPa, the slurry is preheated after being pressurized by a high pressure pump, the temperature of the slurry is raised to 150-250℃, and the temperature of the drying hot air in the tower is 120-150℃.

7. The method for preparing highly conductive and thermally conductive sheet-like gallium indium-doped AZO as described in claim 1, characterized in that, In step i), a heatable vertical stirring mill is used, which is filled with glass beads with an effective volume of 15-30%, the maximum heating temperature is 150℃, a coupling agent reaction liquid atomizing nozzle is fixed on the top cover, the liquid pressure is 0.5-1.5 MPa, the sintered AZO powder is first filled, the agglomeration of the powder is broken by the grinding action of the glass beads, then the silane coupling agent reaction liquid is sprayed while stirring, after spraying, the stirring is continued until the liquid is uniformly dispersed in the powder, then heating is performed, the temperature is between 80-120℃, and the moisture is less than 1%.

8. The method for preparing highly conductive and thermally conductive sheet-like gallium indium-doped AZO as described in claim 2, characterized in that, A continuous production device is used for preparation, the device includes a jacketed stainless steel reaction kettle with double dispersion and stirring, a spray drying tower, a continuous sintering furnace, a vertical stirring mill and a packaging equipment connected in sequence through liquid and slurry conveying pumps and a transmission belt, the liquid raw material of the reaction kettle is introduced into the reaction kettle from the reaction liquid preparation tank through a metering pump, the graphene oxide powder is manually added into the reaction kettle, and the filter cake is returned to the reaction kettle through the transmission belt.

9. A high conductive and high thermal sheet-shaped gallium-indium doped AZO prepared by the method of any one of claims 1-8, characterized in that, The flaky gallium indium doped AZO has a flaky morphology, the length to thickness ratio is greater than 20, and the average particle size is greater than 2 microns.

10. A polymer composite, characterized by, The high thermal and electrical conductivity flaky gallium indium doped AZO powder is prepared by using the flaky gallium indium doped AZO powder of claim 9, and the thermal and electrical conductivity of the polymer composite is more than 2 times higher than that of an irregular shape gallium indium doped AZO powder composite with the same volume content.

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