Manufacturing method and application of aluminum oxide coated bismuth oxide powder

Abstract

The invention provides a preparation method of aluminum oxide coated bismuth oxide powder, which comprises the following steps: preparing a bismuth oxide-aluminum oxide structure through a hydrothermal synthesis method, removing a pore forming agent through subsequent sintering to prepare bismuth oxide-porous aluminum oxide, and finally loading a flame retardant on a porous aluminum oxide shell layer through an impregnation method to prepare bismuth oxide composite particles. According to the preparation method disclosed by the invention, by preparing a core-shell structure with a porous shell, the range of bismuth oxide with high activity is limited, so that the situation that the stability of a finished product is influenced due to agglomeration of the bismuth oxide with high activity in the preparation process of the high polymer material is avoided; meanwhile, core layer bismuth oxide and the flame retardant loaded on the porous aluminum oxide shell layer rapidly react under the high-temperature condition, a bismuth phosphate compact layer is generated, oxygen and heat are isolated, so that the flame retardant property of the material is improved, meanwhile, due to the bismuth oxide and porous aluminum oxide structure, the density of the filler is greatly reduced, and development of a high-function light-weight material is promoted.

Description

Technical Field

[0001] The present invention relates to the technical field of polymer material preparation, and specifically relates to a manufacturing method of alumina-coated bismuth oxide powder and its application in polymer material preparation. Background Art

[0002] Bismuth oxide is an important inorganic functional material. When bismuth oxide decomposes at high temperature to generate free radicals, the combustion chain reaction can be interrupted. Therefore, when preparing polymer materials, the flame retardancy of the materials is often improved by adding <10% of bismuth oxide powder. However, due to the photocatalytic activity of bismuth oxide, reactive oxygen species can be generated under visible light or ultraviolet light irradiation, which will oxidize the sensitive groups in the polymer material to generate chromogenic groups. The accumulation of oxidation products will cause the material to turn yellow or even brown. At the same time, when highly active bismuth oxide is heated and mixed in the polymer material, it catalyzes the cleavage of molecular chains to generate low-molecular-weight degradation products, reducing the product performance. And this negative impact will be significantly enhanced with the increase of the bismuth oxide addition amount and the decrease of the bismuth oxide powder particle size.

[0003] In the prior art, Ube Industries of Japan developed a PA66 composite material coated with alumina on bismuth oxide for use in weather-resistant automotive intake pipes. However, by wrapping the outside of bismuth oxide with alumina to completely isolate the contact between bismuth oxide and the polymer material, although it can avoid the problem of catalytic decomposition of polymer chains caused by the high activity of bismuth oxide during production and later use, it also greatly limits the flame retardant properties of bismuth oxide. Therefore, how to retain the flame retardant properties of bismuth oxide while reducing its negative effects on the material is an issue that cannot be ignored in the application of bismuth oxide as a high-functional filler in polymer materials. Summary of the Invention

[0004] (1) Technical Problems to be Solved

[0005] In view of the deficiencies of the prior art, the present invention provides a manufacturing method and application of alumina-coated bismuth oxide powder to solve the problems raised in the above background art.

[0006] (2) Technical Solutions

[0007] To achieve the above objectives, the present invention is realized through the following technical solutions: A manufacturing method of alumina-coated bismuth oxide powder includes the following steps:

[0008] ① Prepare an aluminum salt solution, add bismuth oxide powder, a dispersant, and a pore-forming agent to the aluminum salt solution, and stir evenly to obtain a reaction solution;

[0009] Among them, the concentration of aluminum ions is 0.1 - 0.5 mol / L, the molar ratio of aluminum ions to bismuth ions is 3 - 5:1, the mass ratio of bismuth oxide to the dispersant is 1:0.01 - 0.05, and the mass ratio of the aluminum salt to the pore-forming agent is 1:0.05 - 0.1;

[0010] ② Add a precipitating agent and a complexing agent to the reaction solution in sequence. After mixing evenly, transfer it to a reaction kettle, seal it, and carry out a hydrothermal reaction at 150 - 170 °C for 3 - 6 h to obtain a solid-liquid mixture.

[0011] ③ Filter, wash, and dry the solid-liquid mixture in step ② to obtain bismuth oxide@aluminum oxide.

[0012] ④ Place the bismuth oxide@aluminum oxide in a muffle furnace, heat it at a rate of 1 - 2 °C / min to 400 - 600 °C, keep it at a constant temperature for 2 - 4 hours, and then cool it to room temperature with the furnace to obtain bismuth oxide@porous aluminum oxide.

[0013] ⑤ Dissolve the flame retardant in a solution, place the bismuth oxide@porous aluminum oxide prepared in step ④ in the solution, ultrasonically disperse it for 20 - 30 min, filter to remove the solvent, dry it at 60 - 80 °C, and then sinter it at 200 °C for 2 - 4 hours to obtain bismuth oxide composite particles.

[0014] As a further preference, the aluminum salt is one or more of aluminum nitrate, aluminum chloride, and aluminum sulfate.

[0015] As a further preference, the dispersant is one or more of sodium dodecyl sulfate, polyacrylic acid, polyethylene glycol, and citric acid, and more preferably citric acid.

[0016] As a further preference, the pore-forming agent is polyethylene glycol or polyvinylpyrrolidone.

[0017] As a further preference, the precipitating agent is one or more of ammonia water, urea, and ammonium carbonate, and more preferably urea.

[0018] As a further preference, the complexing agent is one or more of citric acid, chitosan, EDTA, and PAA.

[0019] As a further preference, the flame retardant is one of halogen-based flame retardants, phosphorus-based flame retardants, and nitrogen-based flame retardants, and more preferably phosphorus-based flame retardants.

[0020] An application of alumina-coated bismuth oxide powder. The alumina-coated bismuth oxide powder prepared by the above method is used as a high-functional filler in the preparation of high-flame-retardant polymer materials.

[0021] (III) Beneficial effects

[0022] The present invention provides a manufacturing method of alumina-coated bismuth oxide powder, which has the following beneficial effects:

[0023] Through a hydrothermal reaction, the present invention wraps alumina with high thermal conductivity and better thermal stability around the outer wall of bismuth oxide, and by removing the template, a core-shell structure with a porous outer shell is formed to confine highly active bismuth oxide, avoiding the agglomeration of highly active bismuth oxide powder during the preparation of polymer materials and affecting the stability of the finished product. At the same time, a flame retardant is loaded on the porous shell layer. During the use of the material, porous silica reacts and adsorbs bismuth ions freed from the inner core, avoiding the oxidation reaction between bismuth ions and polymers to generate chromogenic groups, resulting in yellowing of the material. When the material is in a high-temperature environment or catches fire, the inner core bismuth oxide reacts rapidly with the flame retardant loaded on the porous alumina shell layer to form a dense layer of bismuth phosphate, isolating oxygen and heat to improve the flame retardancy of the material;

[0024] At the same time, the bismuth oxide@porous alumina structure greatly reduces the density of the filler, which is beneficial to the development of high-functional lightweight materials. Brief Description of the Drawings

[0025] Figure 1 It is a schematic diagram of the preparation process of alumina-coated bismuth oxide powder of the present invention. Detailed Embodiments

[0026] In the present invention, unless otherwise clearly defined and limited, the first feature being "on" or "under" the second feature may include direct contact between the first and second features, or may include the first and second features not being in direct contact but being in contact through other features therebetween. Moreover, the first feature being "above", "over" and "on" the second feature includes the first feature being directly above and obliquely above the second feature, or merely indicating that the first feature has a higher horizontal height than the second feature. The first feature being "under", "beneath" and "under" the second feature includes the first feature being directly below and obliquely below the second feature, or merely indicating that the first feature has a lower horizontal height than the second feature.

[0027] The following disclosure provides many different embodiments or examples for implementing different structures of the present invention. To simplify the disclosure of the present invention, the components and settings of specific examples are described below. Of course, they are only examples and are not intended to limit the present invention. In addition, the present invention may repeat reference numerals and / or reference letters in different examples. Such repetition is for the purpose of simplification and clarity, and does not itself indicate the relationship between the various embodiments and / or settings discussed. In addition, the present invention provides examples of various specific processes and materials, but those of ordinary skill in the art may be aware of the application of other processes and / or the use of other materials.

[0028] On the one hand, the present invention provides a method for manufacturing alumina-coated bismuth oxide powder, including the following steps:

[0029] ① Prepare an aluminum salt solution, add bismuth oxide powder, a dispersant, and a pore-forming agent to the aluminum salt solution, and stir evenly to obtain a reaction solution;

[0030] Among them, the concentration of aluminum ions is 0.1 - 0.5 mol / L, the molar ratio of aluminum ions to bismuth ions is 3 - 5:1, the mass ratio of bismuth oxide to the dispersant is 1:0.01 - 0.05, and the mass ratio of the aluminum salt to the pore-forming agent is 1:0.05 - 0.1;

[0031] In the present invention, the bismuth oxide is industrial-grade bismuth oxide produced by Sinopharm Group, with the model 10023418, a purity of 99.5%, and a particle size distribution range of 3 - 10 μm.

[0032] The aluminum salt is one or more of aluminum nitrate, aluminum chloride, and aluminum sulfate; the dispersant is one or more of sodium dodecyl sulfate, polyacrylic acid, polyethylene glycol, and citric acid, and more preferably citric acid; the pore-forming agent is polyethylene glycol or polyvinylpyrrolidone;

[0033] It should be noted that the raw materials not clearly stated in the present invention are all common commercially available products.

[0034] ② Sequentially add a precipitating agent and a complexing agent to the reaction solution, mix evenly, transfer it to a reaction kettle and seal it, and carry out a hydrothermal reaction at 150 - 170 °C for 3 - 6 h to obtain a solid-liquid mixture;

[0035] Among them, the molar ratio of the precipitating agent to aluminum ions is 3 - 5:1, the precipitating agent is one or more of ammonia water, urea, and ammonium carbonate, and more preferably urea, and the reaction process is gentle and the particle size is more uniform.

[0036] The molar ratio of the complexing agent to aluminum ions is 0.5 - 2:1, and the complexing agent is one or more of citric acid, chitosan, EDTA, and PAA.

[0037] Chitosan needs to be dissolved in a small amount of dilute acetic acid and then added as a complexing agent.

[0038] It should be noted that the initial pH value should be controlled at 3 - 5 to avoid premature precipitation of Al ions, and the hydrothermal kettle needs to be strictly sealed to prevent the decomposition products from escaping and affecting the product morphology.

[0039] ③ Filter, wash, and dry the solid-liquid mixture in step ② to obtain bismuth oxide@aluminum oxide;

[0040] Among them, during washing, first wash with an ethanol aqueous solution (1:1) 3 times to remove the unreacted precipitating agent and complexing agent, and then soak briefly with 0.1 M HNO3 (10 min) to remove the loose Al2O3 particles on the surface.

[0041] ④ Place bismuth oxide@aluminum oxide in a muffle furnace, heat it at a rate of 1 - 2 °C / min to 400 - 600 °C, keep it at a constant temperature for 2 - 4 hours, and then cool it to room temperature with the furnace to obtain bismuth oxide@porous aluminum oxide;

[0042] ⑤ Dissolve the flame retardant in a solution, place the bismuth oxide@porous aluminum oxide prepared in step ④ in the solution, ultrasonically disperse it for 20 - 30 min, filter to remove the solvent, dry it at 60 - 80 °C, and then sinter it at 200 °C for 2 - 4 hours to obtain bismuth oxide composite particles.

[0043] Among them, the flame retardant is one of a halogen - based flame retardant, a phosphorus - based flame retardant, and a nitrogen - based flame retardant, and more preferably a phosphorus - based flame retardant.

[0044] The phosphorus - based flame retardants include one or more of ammonium polyphosphate, ammonium hypophosphite, phosphate ester, DOPO derivatives, melamine polyphosphate (MPP), and aluminum hypophosphite.

[0045] It can be understood that according to the different flame retardants selected, a suitable solution is selected as the solvent. For example, ammonium polyphosphate and ammonium hypophosphite can choose water or ethanol as the solvent for dissolution, phosphate ester can choose ethanol as the solvent, and DOPO derivatives and MPP can choose organic solvents such as acetone, DMF, and toluene.

[0046] Furthermore, considering safety, environmental protection, and operation cost, the more preferred option is an aqueous solution of ammonium polyphosphate or ammonium hypophosphite.

[0047] An application of alumina - coated bismuth oxide powder, using the bismuth oxide composite particles prepared by the above method, is used as a high - functional filler in the preparation of high - flame - retardant polymer materials.

[0048] Weigh 5% - 15% of the total mass of the polymer material system of bismuth oxide composite particles, mix it with the raw materials, and then through melt - blending extrusion, cooling, drying, and pelletizing, high - flame - retardant polymer materials can be obtained.

[0049] It should be noted that in step ⑤, the mass of the flame retardant accounts for 5% - 20% of the mass of the raw materials for preparing the polymer material matrix.

[0050] Among them, the proportions of ammonium polyphosphate, ammonium hypophosphite, aluminum hypophosphite, and phosphate ester are 15% - 20%; the proportions of DOPO derivatives and melamine polyphosphate (MPP) are 5% - 20%.

[0051] To further understand the present invention, the following examples are used to illustrate the bismuth oxide composite particles provided by the present invention. The protection scope of the present invention is not limited by the following examples.

[0052] Example 1

[0053] ① Weigh 56.25 g of aluminum nitrate to prepare an aluminum salt solution. Add 23.3 g of bismuth oxide powder, 0.23 g of citric acid, and 2.8 g of polyethylene glycol to the aluminum salt solution, and stir evenly to obtain a reaction solution.

[0054] ② Adjust the pH value of the reaction solution to 3 - 5 with HNO₃. Add 9 g of urea and 13.4 g of PAA to the reaction solution in sequence. After mixing evenly, transfer it to a reaction kettle and seal it. Carry out hydrothermal reaction at 150 °C for 6 h to obtain a solid-liquid mixture.

[0055] ③ Filter, wash, and dry the solid-liquid mixture in step ② to obtain bismuth oxide@aluminum oxide.

[0056] ④ Place the bismuth oxide@aluminum oxide in a muffle furnace, heat it at a rate of 1 °C / min to 400 °C, keep it at a constant temperature for 4 hours, and then cool it to room temperature with the furnace to obtain bismuth oxide@porous aluminum oxide.

[0057] ⑤ Dissolve 14.9 g of ammonium polyphosphate in water to form a solution. Place the bismuth oxide@porous aluminum oxide prepared in step ④ in the solution, ultrasonically disperse it for 25 min, filter to remove the solvent, dry it at 80 °C, and then sinter it at 200 °C for 2 hours to obtain bismuth oxide composite particles.

[0058] ⑥ Mix the bismuth oxide composite particles prepared in step ⑤ with the raw materials at 5% of the total mass of the polymer material system. After melt blending, extrusion, cooling, and drying, pelletize to obtain a highly flame-retardant polymer material.

[0059] Example 2

[0060] ① Weigh 20 g of aluminum chloride to prepare an aluminum salt solution. Add 23.3 g of bismuth oxide powder, 0.32 g of polyacrylic acid, and 1 g of polyethylene glycol to the aluminum salt solution, and stir evenly to obtain a reaction solution.

[0061] ② Adjust the pH value of the reaction solution to 3 - 5 with HNO₃. Add 26.25 g of ammonia water and 14.4 g of citric acid to the reaction solution in sequence. After mixing evenly, transfer it to a reaction kettle and seal it. Carry out hydrothermal reaction at 170 °C for 3 h to obtain a solid-liquid mixture.

[0062] ③ Filter, wash, and dry the solid-liquid mixture in step ② to obtain bismuth oxide@aluminum oxide.

[0063] ④ Place the bismuth oxide@aluminum oxide in a muffle furnace, heat it at a rate of 1.5 °C / min to 600 °C, keep it at a constant temperature for 2 hours, and then cool it to room temperature with the furnace to obtain bismuth oxide@porous aluminum oxide.

[0064] ⑤ Dissolve 28.3 g of MPP in acetone to form a solution. Place the bismuth oxide@porous aluminum oxide prepared in step ④ in the solution, ultrasonically disperse it for 30 min, filter to remove the solvent, dry it at 60 °C, and then sinter it at 200 °C for 4 hours to obtain bismuth oxide composite particles.

[0065] ⑥Mix the bismuth oxide composite particles prepared in step ⑤ with the raw materials at 10% of the total mass of the polymer material system, and after melt blending extrusion, cooling, drying, and pelletizing, a highly flame-retardant polymer material is obtained.

[0066] Example 3

[0067] ①Weigh 54.3 g of aluminum sulfate to prepare an aluminum salt solution, add 23.3 g of bismuth oxide powder, 1.165 g of polyethylene glycol, and 2.7 g of polyvinylpyrrolidone to the aluminum salt solution, and stir evenly to obtain a reaction solution.

[0068] ②Adjust the pH value of the reaction solution to 3 - 5 with HNO₃, and successively add 45 g of urea and 30.7 g of chitosan - dilute acetic acid solution as the solute to the reaction solution. After mixing evenly, transfer it to a reaction kettle and seal it. Carry out a hydrothermal reaction at 160 °C for 5 h to obtain a solid - liquid mixture.

[0069] ③Filter, wash, and dry the solid - liquid mixture in step ② to obtain bismuth oxide@aluminum oxide.

[0070] ④Place the bismuth oxide@aluminum oxide in a muffle furnace, heat it up to 500 °C at a rate of 2 °C / min, keep it at a constant temperature for 3 hours, and then cool it to room temperature with the furnace to obtain bismuth oxide@porous aluminum oxide.

[0071] ⑤Dissolve 18.3 g of ammonium hypophosphite in ethanol to form a solution. Place the bismuth oxide@porous aluminum oxide prepared in step ④ in the solution, ultrasonically disperse it for 20 min, filter to remove the solvent, dry it at 70 °C, and then sinter it at 200 °C for 3 hours to obtain bismuth oxide composite particles.

[0072] ⑥Mix the bismuth oxide composite particles prepared in step ⑤ with the raw materials at 15% of the total mass of the polymer material system, and after melt blending extrusion, cooling, drying, and pelletizing, a highly flame - retardant polymer material is obtained.

[0073] Comparative Example 1

[0074] ①Weigh 20 g of aluminum chloride to prepare an aluminum salt solution, add 23.3 g of bismuth oxide powder and 0.32 g of polyacrylic acid to the aluminum salt solution, and stir evenly to obtain a reaction solution.

[0075] ②Adjust the pH value of the reaction solution to 3 - 5 with HNO₃, and successively add 26.25 g of ammonia water and 14.4 g of citric acid to the reaction solution. After mixing evenly, transfer it to a reaction kettle and seal it. Carry out a hydrothermal reaction at 170 °C for 3 h to obtain a solid - liquid mixture.

[0076] ③Filter, wash, and dry the solid - liquid mixture in step ②, then place it in a muffle furnace, heat it up to 600 °C at a rate of 1.5 °C / min, keep it at a constant temperature for 2 hours, and then cool it to room temperature with the furnace to obtain bismuth oxide@aluminum oxide.

[0077] ④ Dissolve 28.3 g of MPP in acetone to make a solution. Place the bismuth oxide@aluminum oxide prepared in step ③ into the solution, ultrasonically disperse for 30 min, filter to remove the solvent, dry at 60 °C, and then sinter at 200 °C for 4 hours to obtain bismuth oxide@aluminum oxide supported particles.

[0078] ⑤ Mix the bismuth oxide@aluminum oxide supported particles prepared in step ④ with the raw materials at 10% of the total mass of the polymer material system. After melt blending extrusion, cooling, and drying, pelletize to obtain the polymer material of the comparative example.

[0079] Comparative Example 2

[0080] ① Weigh 20 g of aluminum chloride to prepare an aluminum salt solution. Add 23.3 g of bismuth oxide powder and 0.32 g of polyacrylic acid to the aluminum salt solution, and stir evenly to obtain a reaction solution.

[0081] ② Adjust the pH value of the reaction solution to 3 - 5 with HNO3. Add 26.25 g of ammonia water and 14.4 g of citric acid to the reaction solution in sequence. After mixing evenly, transfer it to a reaction kettle and seal it. Carry out hydrothermal reaction at 170 °C for 3 h to obtain a solid-liquid mixture.

[0082] ③ Filter, wash, and dry the solid-liquid mixture in step ②, then place it in a muffle furnace. Heat it at a rate of 1.5 °C / min to 600 °C, keep it at a constant temperature for 2 hours, and then cool it to room temperature with the furnace to obtain bismuth oxide@aluminum oxide.

[0083] ④ Mix the bismuth oxide@aluminum oxide prepared in step ③ with 28.3 g of MPP, and at a mass ratio of 10% of the total mass of the polymer material system, mix it with the raw materials. After melt blending extrusion, cooling, and drying, pelletize to obtain the polymer material of the comparative example.

[0084] Comparative Example 3

[0085] ① Weigh 20 g of aluminum chloride to prepare an aluminum salt solution. Add 23.3 g of bismuth oxide powder, 0.32 g of polyacrylic acid, and 1 g of polyethylene glycol to the aluminum salt solution, and stir evenly to obtain a reaction solution.

[0086] ② Adjust the pH value of the reaction solution to 3 - 5 with HNO3. Add 26.25 g of ammonia water and 14.4 g of citric acid to the reaction solution in sequence. After mixing evenly, transfer it to a reaction kettle and seal it. Carry out hydrothermal reaction at 170 °C for 3 h to obtain a solid-liquid mixture.

[0087] ③ Filter, wash, and dry the solid-liquid mixture in step ② to obtain bismuth oxide@aluminum oxide.

[0088] ④ Place the bismuth oxide@aluminum oxide in a muffle furnace. Heat it at a rate of 1.5 °C / min to 600 °C, keep it at a constant temperature for 2 hours, and then cool it to room temperature with the furnace to obtain bismuth oxide@porous aluminum oxide.

[0089] ⑤Mix the bismuth oxide@porous alumina prepared in step ④ with 28.3 g of MPP, and mix it with the raw materials at a mass ratio of 10% of the total mass of the polymer material system. After melt blending extrusion, cooling, drying, and pelletizing, the polymer material of the comparative example is obtained.

[0090] Comparative Example 4

[0091] Weigh 23.3 g of bismuth oxide, 28.3 g of MPP, and 15.15 g of alumina, mix them, and mix them with the raw materials at a mass ratio of 10% of the total mass of the polymer material system. After melt blending extrusion, cooling, drying, and pelletizing, the polymer material of the comparative example is obtained.

[0092] Test Example:

[0093] Take the polymer materials prepared in Examples 1 to 3 and Comparative Examples 1 to 4 for the following tests:

[0094] Flame retardancy test: Inject the material into a 120*12*2 mm spline and measure it according to the American UL94 fire prevention standard.

[0095] Burning experiment: Inject the material into a 100*100*3 mm sample plate, conduct a burning experiment using liquefied petroleum gas, set the gas flow rate at 0.5 MPa through a fixed pressure reducing valve, set the flame temperature at 1000 °C through an infrared thermometer, keep the torch 50 mm away from the sample plate for continuous burning, record the burning and breaking time of the sample plate, and measure the hardness of the carbon layer with a Shore hardness tester (Type A) after cooling to room temperature. Take the average value of five groups of carbon layer hardness tests.

[0096] UV aging test: Inject the material into a 100×50 mm sample plate and ensure that the surface is clean and pollution-free. Select the lamp type UVB~313, irradiance 1~1.55 W / m 2 、circulation mode (4 hours of UV (60 °C) + 4 hours of condensation (50 °C)) to observe the color difference (ΔE), glossiness (60° angle), and surface cracks of the material.

[0097] Among them, the cracks are evaluated according to the ISO 4628-4:2016 standard by combining visual inspection (comparing with the standard grade chart) and optical microscope (measuring the width and density of microcracks).

[0098] Table 1 is the test statistical table of each example and comparative example

[0099]

[0100] In summary, by wrapping porous alumina around the bismuth oxide powder and loading a flame retardant on the porous alumina, the direct contact between the active sites in the bismuth oxide and the polymer material can be effectively blocked, thus solving the problems of catalytic and oxidative decomposition of the polymer chains during the preparation process. Moreover, during long-term subsequent use, the bismuth oxide absorbs and scatters ultraviolet light, which can effectively delay the aging of the material. At the same time, the porous alumina adsorbs free bismuth ions, avoiding the yellowing of the material caused by the oxidation reaction between the bismuth ions and the polymer active groups. Additionally, at high temperatures, the flame retardant loaded on the shell reacts rapidly with the bismuth oxide in the core to form a dense layer of bismuth phosphate, effectively isolating oxygen and heat and greatly improving the flame retardancy of the material.

[0101] Although the embodiments of the present invention have been shown and described, it will be understood by those of ordinary skill in the art that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of the present invention, and the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for manufacturing alumina-coated bismuth oxide powder, characterized in that, It includes the following steps: ① Prepare an aluminum salt solution, add bismuth oxide powder, a dispersant and a pore-forming agent into the aluminum salt solution, and stir evenly to obtain a reaction solution; Among them, the concentration of aluminum ions is 0.1 - 0.5 mol / L, the molar ratio of aluminum ions to bismuth ions is 3 - 5:1, the mass ratio of bismuth oxide to the dispersant is 1:0.01 - 0.05, and the mass ratio of the aluminum salt to the pore-forming agent is 1:0.05 - 0.1; ② Sequentially add a precipitating agent and a complexing agent to the reaction solution, mix evenly, transfer it to a reaction kettle and seal it, carry out a hydrothermal reaction at 150 - 170 °C for 3 - 6 h to obtain a solid-liquid mixture; ③ Filter, wash and dry the solid-liquid mixture in step ② to obtain bismuth oxide@aluminum oxide; ④ Place the bismuth oxide@aluminum oxide in a muffle furnace, heat it up at 1 - 2 °C / min to 400 - 600 °C, keep it at a constant temperature for 2 - 4 hours, and then cool it to room temperature with the furnace to form a core-shell structure with porous outer shell, obtaining bismuth oxide@porous aluminum oxide; ⑤ Dissolve the flame retardant in a solution, place the bismuth oxide@porous aluminum oxide prepared in step ④ in the solution, ultrasonically disperse it for 20 - 30 min, filter to remove the solvent, dry it at 60 - 80 °C, and sinter it at 200 °C for 2 - 4 hours to obtain bismuth oxide composite particles.

2. The manufacturing method of an alumina-coated bismuth oxide powder according to claim 1, characterized in that: The aluminum salt is one or more of aluminum nitrate, aluminum chloride, and aluminum sulfate.

3. The manufacturing method of an alumina-coated bismuth oxide powder according to claim 1, characterized in that: The dispersant is one or more of sodium dodecyl sulfate, polyacrylic acid, polyethylene glycol, and citric acid, and more preferably citric acid.

4. The manufacturing method of an alumina-coated bismuth oxide powder according to claim 1, characterized in that: The pore-forming agent is polyethylene glycol or polyvinylpyrrolidone.

5. The manufacturing method of an alumina-coated bismuth oxide powder according to claim 1, characterized in that: The precipitating agent is one or more of ammonia water, urea, and ammonium carbonate, and more preferably urea.

6. The manufacturing method of an alumina-coated bismuth oxide powder according to claim 1, wherein: The complexing agent is one or more of citric acid, chitosan, EDTA, and PAA.

7. The manufacturing method of an alumina-coated bismuth oxide powder according to claim 1, characterized in that: The flame retardant is one of a halogen-based flame retardant, a phosphorus-based flame retardant, and a nitrogen-based flame retardant, and more preferably a phosphorus-based flame retardant.

8. Application of alumina-coated bismuth oxide powder, characterized in that, The bismuth oxide composite particles prepared by using the method described in any one of claims 1 - 7 are used as high-functional fillers in the preparation of high-flame-retardant polymer materials.

9. The application of an alumina-coated bismuth oxide powder according to claim 8, wherein The bismuth oxide composite particles account for 5% - 15% of the total mass of the polymer material system.

Images