A method for dispersing modified vanadium dioxide in a hydrophilic system and its slurry product.

Abstract

This invention belongs to the field of slurry preparation technology, specifically disclosing a method for dispersing modified vanadium dioxide in a hydrophilic system and the resulting slurry product. The dispersion method employs a combined dry and wet process, with the following steps: First, micron-sized VO₂ powder is pre-pulverized using dry airflow milling to obtain a pre-refined pulverized product; then, this pulverized product, additive A, and a hydrophilic solvent S are mixed in a specific ratio to form an initial slurry; finally, the initial slurry is further finely dispersed using a sand milling process, during which additives B and C are added stepwise to the intermediate slurry. This invention effectively solves the agglomeration problem during the nano-sizing of VO₂, stably preparing target powders with a particle size of 50-100 nm. The prepared slurry exhibits excellent dispersibility and long-term stability, making it particularly suitable for the industrial production of intelligent temperature-controlled coatings.

Description

Technical Field

[0001] This invention relates to the technical field of slurry preparation methods, specifically to a method for dispersing modified vanadium dioxide in a hydrophilic system and the slurry product thereof. Background Technology

[0002] In recent years, vanadium dioxide (VO2) materials have attracted widespread attention due to their intrinsic temperature-induced phase transition characteristics. When the ambient temperature exceeds its phase transition critical value, monoclinic VO2 (M phase) can reversibly transform into rutile VO2 (R phase), resulting in a significant change in infrared transmittance and enabling dynamic control of solar thermal radiation. Based on this temperature-responsive optical property, VO2 shows great application potential in the field of smart optical windows.

[0003] Nevertheless, the application of VO2 and slurry preparation still face the following prominent problems: (1) The intrinsic phase transition temperature of pure monoclinic VO2 material is about 68 ℃, which is significantly higher than the temperature range that is comfortable for the human body. This results in the temperature modulation range of infrared thermal radiation being incompatible with the working temperature requirements of actual application scenarios. (2) Defect treatment of VO2 (bulk doping) can significantly reduce the phase transition temperature to 25~40℃, which can meet the needs of practical applications. However, due to the increased complexity of the material formulation and the stricter process parameters, the nanoparticles agglomerate severely during the sintering preparation process (the particle size can reach 5~10 μm), resulting in rapid powder sedimentation in the slurry and poor uniformity. This not only greatly hinders the feasibility of slurry coating and film formation, but also significantly weakens the optical performance of the product.

[0004] Therefore, the current low-cost methods for refining bulk VO2-doped powders mainly involve crushing and grinding. Conventional dry ball milling is difficult to independently and stably crush powder particles to below 100 nm and is prone to local overheating. For conventional wet ball milling, sand milling, and high-pressure homogenization, there is currently a lack of innovative processes that cannot maintain stable slurry dispersion while stably crushing powder particles to below 100 nm.

[0005] Conventional ball milling has significant limitations: dry ball milling struggles to stably break particles down to below 100 nm, and mechanical impact can easily cause localized overheating, leading to VO2 phase transformation and deactivation. While wet ball milling can alleviate overheating, it is prone to hard agglomeration due to mechanical media contamination or insufficient dispersion, also failing to achieve stable nanoscale refinement. Even with a combined "ball milling + sand milling" process, the pretreatment stage of ball milling introduces surface defects or agglomeration risks, which are difficult to completely eliminate in subsequent sand milling, making it impossible to simultaneously achieve refinement below 100 nm and long-term dispersion stability of the slurry. Therefore, patent literature on VO2 powder, such as invention patents CN201710480000.X and CN201710480405.3, tends to directly use pure monoclinic VO2 powder to circumvent the aforementioned process difficulties, and controls the VO2 mass solids content within the range of 2% to 5%.

[0006] Besides powder refinement, existing technologies also have certain shortcomings in improving the dispersibility of VO2 powder. For example, the ultrasonic dispersion method disclosed in invention patent CN201710480000.X has limited effect on slurries with high solid content and is difficult to apply on a large scale compared with wet grinding; invention patent application CN202310914840.8 only uses polyvinylpyrrolidone (PVP) as a single-component dispersant and binder, while invention patent application CN202411510720.2 uses a high-viscosity polycarboxylate dispersion system, and both dispersion systems have shortcomings.

[0007] To address the aforementioned problems and technical shortcomings, there is an urgent need to develop a novel fine dispersion process suitable for industrial scale-up. This process must balance the good dispersibility of small-particle-size target powders and slurries. A significant advantage of this process is the ability to flexibly select modified VO2 powders with different particle size ranges, thereby reducing costs, increasing production capacity, achieving good industrial economic benefits, and promoting the widespread application of VO2 nanomaterials in the field of intelligent optics. Summary of the Invention

[0008] The purpose of this invention is to provide a method for dispersing modified vanadium dioxide in a hydrophilic system to solve the problem of good dispersibility of target powders and slurries with small particle size as mentioned in the background art, and to disclose a slurry product obtained according to the dispersion method.

[0009] To solve the above-mentioned technical problems, the present invention provides the following technical solution: A method for dispersing modified vanadium dioxide in a hydrophilic system includes the following steps: (1) Dry airflow pre-pulverization: Micron-sized X-VO2 powder is placed in an airflow pulverizer, and pre-cooled inert gas is introduced as the pulverizing medium. The total pulverization time is 50~100 minutes to obtain the pre-refined pulverized product. (2) Initial slurry preparation: The crushed product obtained in step (1) is mixed with hydrophilic solvent S, and additive A is added at the same time. After stirring evenly, an initial slurry is formed. (3) Fine dispersion by sand milling: The initial slurry obtained in step (2) is added to the sand mill. During the sand milling process, the temperature of the initial slurry is kept at 25~30 ℃. Additives B and C are added step by step during the sand milling process. The sand milling is continued for 4~6 hours to obtain a slurry with a particle size of 50~100 nm.

[0010] Further, the inert gas mentioned in step (1) is nitrogen or argon with a purity ≥99.9%, the temperature of the pre-cooled inert gas is 5~15 ℃, and the gas flow pressure of the inert gas is 0.5~0.8 MPa; The micron-sized X-VO2 powder is M-phase vanadium dioxide with an average particle size of 5~10 μm. X in the micron-sized X-VO2 powder is a doping element, and the doping element X is at least one of magnesium, tungsten, molybdenum, niobium, terbium, europium, boron or fluorine. Its particle size range is much larger than the target particle size of 50~100 nm.

[0011] Currently, pure monoclinic VO2 (M phase) can easily produce powder particles with a particle size of 50-100 nm. However, after bulk doping with other elements, the particle size of X-VO2 powder, such as in this invention, tends to increase significantly due to increased crystal structure defects during hydrothermal / solvothermal and sintering processes. This makes refinement modification during synthesis difficult and is expected to be costly. Therefore, this invention improves the process by performing preliminary dispersion and fine dispersion of larger-particle-size (5-10 μm) X-VO2 powder in a two-step process, achieving integrated powder refinement and related slurry preparation, thereby effectively bridging the gap between raw materials and applications.

[0012] The classifying wheel speed of the airflow crusher is 3000~6000 rpm. After continuous crushing for 20 minutes, the machine is stopped for 5 minutes, and the total crushing time is 50~100 minutes. Using dry air jet milling as a preliminary dispersion method, larger particles with a diameter of 5~10 μm can be quickly broken up. This process drives the particles to produce a dual effect of "elastic collision" and "air shearing" through high-speed inert airflow. It is especially suitable for the preliminary processing of brittle and hard particles with a diameter of micron and above and a wide particle size distribution. Its core advantages are that the absence of mechanical medium contact avoids lattice contamination, the high-speed airflow shearing force is controllable to avoid lattice distortion caused by mechanical stress, and the low-temperature inert gas environment can remove heat in real time, effectively preventing X-VO2 from undergoing continuous phase change deactivation due to temperature rise. It is particularly suitable for the requirement of vanadium dioxide to "refine the particle size and retain the phase change function".

[0013] Furthermore, the hydrophilic solvent S includes an organic solvent and deionized water, wherein the organic solvent is a polar organic solvent and does not contain halogens, and the organic solvent is at least one selected from glycerol, propylene glycol, ethylene glycol, diethylene glycol, ethanol, diethylene glycol monomethyl ether, ethylene glycol butyl ether, trimethyl phosphate, triethyl phosphate, or triethanolamine. In the hydrophilic solvent S, the mass of deionized water is less than 10% of the mass of the organic solvent; When a small amount of deionized water is added to the organic solvent component, the overall solvent becomes macroscopically homogeneous and miscible. Furthermore, the polarity of the overall solvent is enhanced through the hydrogen bonding of water molecules. This further promotes the dissolution of the additive in the system while avoiding side reactions between water molecules and vanadium with +4 valence.

[0014] In addition, organic solvents are miscible with water in a certain proportion. The molecular structure of organic solvents is polar and does not contain halogens. They not only have good solubility for various types of additives, but also have the advantages of being environmentally friendly and less toxic compared to non-polar aromatic hydrocarbons and polar halogen solvents.

[0015] In step (2), the mass ratio of the hydrophilic solvent S to the micron-sized X-VO2 powder is 4~6:1. Within this mass ratio range, it can effectively prevent insufficient refining and dispersion caused by excessive solid content in the powder, and the solid content is significantly improved compared to the prior art. For example, the prior art represented by invention patents CN201710480000.X and CN201710480405.3 has limited ability to disperse nano-VO2, and can only achieve a low mass solid content concentration of 2%~5% in both oily and watery systems.

[0016] Furthermore, additive A comprises a reduced A1 component and a coordination A2 component; Component A1 contains at least one characteristic structure selected from amide, thioamide, sulfonyl, amino, or imino groups; component A2 contains at least one characteristic structure selected from carbon-oxygen heterocycles, imidazole rings, and nitrazole rings.

[0017] Component A1 is preferably any one of acetamide, acrylamide, urea, thiourea, thioacetamide, dimethyl sulfone, dicyandiamide, or N-hydroxysuccinimide, and the amount added each time is 0.5% to 2% of the mass of the micron-sized X-VO2 powder; Component A2 is preferably any one of 18-crown ether-6, 15-crown ether-5, 12-crown ether-4, glucose, fructose, galactose, 2-methylimidazole, 2-aminoimidazole, 1,2,4-triazole, or benzotriazole, and the amount added each time is 0.5% to 1% of the mass of the micron-sized X-VO2 powder.

[0018] Additive A (components A1 and A2) is added in a single step after dry crushing and before sand milling. Its main function is to prevent irreversible structural damage to the X-VO2 powder during subsequent grinding, thus avoiding hindered refining and poor dispersion. Specifically, the addition of additive A occurs during the transitional stage between dry crushing and grinding. At this point, good dispersibility of the material is not required; the focus is on providing pretreatment protection for subsequent grinding by pre-constructing a protective layer on the particle surface through the synergistic effect of A1 and A2. During this process, the continuous shear force from grinding may irreversibly damage the X-VO2 powder in the form of lattice distortion or oxidation phase transition. Therefore, it is necessary to add composite additive A, which consists of components A1 and A2 with different mechanisms of action.

[0019] Additives A, B, and C are a stabilizer, a dispersant, and a surface modifier, respectively. Additives A, B, and C are all non-ionic organic additives that do not contain acidic groups. This prevents charge neutralization and agglomeration after adsorption between ions and charged groups and the powder, and also avoids the reaction of acidic groups with X-VO2, which could cause corrosion and deterioration of the powder.

[0020] Furthermore, additive B is selected from any two of polyethylene glycol monooleate (PEG-MO), polyethylene glycol monolaurate (PEG-ML), fatty alcohol polyoxyethylene ether (AEO), castor oil polyoxyethylene ether (EL), octylphenol polyoxyethylene ether (OP), polyvinylpyrrolidone (PVP), Triton (TX), or phenacetin; the amount of additive B added is 20%~30% of the mass of the micron-sized X-VO2 powder. Unlike ionic dispersants, nonionic additive B, which does not contain acidic groups, interacts with X-VO2 powder and other solvents simultaneously through its hydrophilic and lipophilic polymer chains. With the help of sand milling, it breaks up agglomerates and further slows down subsequent agglomeration through steric hindrance; at the same time, it does not produce side reactions such as powder flocculation and corrosion due to the introduction of ionic and acidic groups.

[0021] Furthermore, additive C is selected from any one of the following surface modifier components: aminosilane KH-540, aminosilane KH-901, aminosilane FD-593, epoxysilane KH-561, mercaptosilane KH-590, pyrophosphate titanate coupling agent KR-38S, pyrophosphate titanate coupling agent KR-238S, or aluminum zirconium coupling agent UP-108; the components in additive C do not undergo violent hydrolysis reactions when exposed to water or moisture at room temperature. The amount of additive C added is 1.5% to 2% of the mass of the micron-sized X-VO2 powder.

[0022] Further, during the operation of step (3), additive B and additive C are added in sequence as follows: additive B is added at a constant speed during the first 2 hours of sand milling, and additive C is added at a constant speed during the remaining time of sand milling until the sand milling ends; the constant speed addition method is a peristaltic pump or a flow pump.

[0023] During the sand milling process, the order in which additives B and C are added is fixed and preferred. Additive B plays a role in the initial physical dispersion stage, suitable for slurries with larger particle sizes in the early stages of sand milling. It achieves dynamic crushing and dispersion through steric hindrance and physical adsorption. Additive C plays a role in the later chemical dispersion stage, suitable for the later stages of sand milling with smaller particle sizes. Through chemical methods, it effectively overcomes the tendency of nanoparticles to agglomerate, achieving fine dispersion.

[0024] The milling speed is 5000~6000 rpm, the initial slurry circulation rate is 100~150 mL / min, and the cumulative operation time is 4~6 hours. During the milling process, the working temperature of the intermediate slurry is maintained at 25~30℃ through liquid cooling. Due to the limitations of dry process characteristics, it is difficult to completely eliminate soft agglomerates between fine particles, and coarse particles at the tail end are easily left in the particle size distribution, affecting the subsequent dispersion effect. Wet milling can make up for this limitation: it uses the continuous shearing action of the grinding media and the synergistic effect of solvent-dispersant to further refine the residual coarse particles, while the uniform coating of the surface of the newly formed particles by the dispersant builds a stable barrier.

[0025] The present invention also provides a slurry prepared according to the above-described method for dispersing modified vanadium dioxide in a hydrophilic system.

[0026] Furthermore, the final average particle size of X-VO2 in the slurry is 50~100 nm.

[0027] The present invention has the following beneficial effects: This invention provides a highly efficient dispersion method for modified vanadium dioxide in a hydrophilic system, which includes a synergistic process of dry air jet milling and wet sand milling. Air jet milling achieves initial refinement through high-speed inert airflow, avoiding local overheating and mechanical contamination, and laying a uniform pretreatment foundation for sand milling. Subsequent sand milling, with the help of fine shearing and dispersant synergy, deeply dissociates agglomerates and stabilizes nanoparticles, ultimately achieving the preparation of a stable and highly dispersed slurry with particles smaller than 100 nm. This effectively overcomes the defects of large particle size and poor dispersibility of X-VO2 powder during slurry processing, and promotes the application of vanadium dioxide in intelligent and energy-saving optics.

[0028] The hydrophilic solvent S used in the initial dispersion of this invention not only has good solubility for various types of additives, but also has the advantages of being environmentally friendly and having low toxicity compared to non-polar aromatic hydrocarbons and polar halogen solvents.

[0029] The hydrophilic solvent S initially dispersed in this invention, in addition to the organic solvent component, enhances the overall polarity of the solvent through hydrogen bonding of water molecules after the addition of a small amount of deionized water. This further promotes the dissolution of the additive in the system while effectively avoiding side reactions between water molecules and +4 valent vanadium.

[0030] The additives A, B and C used in this invention are all non-ionic organic additives that do not contain acidic groups. They can prevent the charge neutralization and agglomeration of ions and charged groups after adsorption with the powder, and at the same time avoid the reaction of acidic groups with X-VO2 powder, which would cause the powder to corrode and deteriorate. Attached Figure Description

[0031] Figure 1 This is a schematic diagram of the dispersion process of the modified vanadium dioxide of the present invention; Figure 2 These are still photographs of the slurries prepared in Examples 1-3 and Comparative Examples 1-5 of the present invention. Figure 3 These are the original powder particle size distribution curves used in Examples 1-3 and Comparative Examples 1-5 of the present invention; Figure 4 Comparison of particle size distribution curves of the slurries prepared in Examples 1-3 of this invention; Figure 5 The particle size distribution curves of the slurries prepared in Example 3 and Comparative Examples 1-5 of this invention are compared. Detailed Implementation The technical solution of the present invention will be clearly and completely described below with reference to specific embodiments. Experimental methods in the following embodiments that do not specify specific conditions are generally performed under conventional conditions or conditions recommended by the manufacturer. Furthermore, the raw materials and reagents used in the present invention can be obtained by purchasing commercially available raw materials or synthesizing them through traditional chemical conversion methods. Unless otherwise defined or stated, all technical and scientific terms used herein have the same meaning as those skilled in the art. The particle size distribution curves of the tungsten-doped vanadium dioxide powder used in the following specific embodiments and comparative examples are shown below. Figure 3 As shown, its average particle size is 6.5 μm.

[0032] The following description of embodiments is for illustrative purposes only and is intended to help understand the present invention. It should be noted that those skilled in the art can make several obvious modifications to the present invention without departing from its principles, and these modifications and alterations also fall within the scope of the claims.

[0033] Example 1: The tungsten-doped vanadium dioxide powder is treated as follows, with the complete process flow diagram shown below. Figure 1 As shown.

[0034] (1) Dry airflow pre-pulverization: 50 g of tungsten-doped vanadium dioxide powder was placed in an airflow crusher, and argon gas with a purity of 99.9% that had been pre-cooled to 5~15 ℃ was introduced as the crushing medium. The airflow pressure was controlled at 0.6 MPa, the classifier speed was 5000 rpm, and the crushing was carried out continuously for 20 minutes, then stopped for 5 minutes, and then continued to crush for 20 minutes, then stopped for 5 minutes. The total crushing time was 50 minutes, and the pre-refined crushed product was obtained. (2) Initial slurry preparation: The crushed product obtained in step (1) is mixed with 300 g of diethylene glycol monomethyl ether, and 1 g of acrylamide and 0.5 g of 12-crown ether-4 are added at the same time. After stirring evenly, the initial slurry is formed. (3) Fine dispersion by sand milling: The initial slurry obtained in step (2) is transferred into a sand mill, and zirconia beads with a diameter of 0.1 mm are used as the grinding medium. The sand milling speed is controlled at 5000~6000 rpm and the initial slurry circulation flow rate is 100~150 mL / min. During the sand milling process, the working temperature of the slurry is maintained at 25~30 ℃ by liquid cooling.

[0035] During the sand milling process, 2.5 g of polyethylene glycol monooleate PEG4000MO and 7.5 g of fatty alcohol polyoxyethylene ether AEO-9 were first pre-dissolved in 25 g of diethylene glycol monomethyl ether and injected into the sand mill at a constant flow rate of 17.5 g / h via a peristaltic pump for 2 hours. Subsequently, 1 g of aminosilane KH-540 was dispersed in 25 g of diethylene glycol monomethyl ether and added uniformly at a flow rate of 13 g / h. The sand milling continued for 2 hours to obtain the target slurry.

[0036] The initial slurry circulation rate in step (3) above is due to the sand mill's slurry processing mode, which uses a circulating process. The sand mill is equipped with a dedicated liquid storage device. After the slurry is discharged from the inside of the sand mill, it is transported to the liquid storage device for temporary storage through pipelines, and then pumped back into the sand mill for continuous grinding, forming a closed-loop circulation process of "grinding-discharge-temporary storage-return". This method ensures that the slurry is fully and uniformly processed during the grinding process, improving the overall grinding efficiency and material fineness.

[0037] Example 2: (1) Dry airflow pre-pulverization: 50 g of tungsten-doped vanadium dioxide powder was placed in an airflow crusher, and argon gas with a purity of 99.9% that had been pre-cooled to 5~15 ℃ was introduced as the crushing medium. The airflow pressure was controlled at 0.6 MPa, the classifier speed was 5000 rpm, and the crushing was carried out continuously for 20 minutes. Then the machine was stopped for 5 minutes. The total crushing time was 100 minutes, and the pre-refined crushed product was obtained. (2) Initial slurry preparation: The crushed product obtained in step (1) is mixed with 200 g propylene glycol, 15 g ethanol and 15 g deionized water, and 0.5 g acetamide and 0.5 g 18-crown ether-6 are added at the same time. After stirring evenly, the initial slurry is formed. (3) Fine dispersion by sand milling: The initial slurry obtained in step (2) is transferred into a sand mill, and zirconia beads with a diameter of 0.1 mm are used as the grinding medium. The sand milling speed is controlled at 5000~6000 rpm and the initial slurry circulation flow rate is 100~150 mL / min. During the sand milling process, the working temperature of the slurry is maintained at 25~30 ℃ by liquid cooling. First, 5.5 g of polyethylene glycol monooleate PEG4000MO and 7.5 g of fatty alcohol polyoxyethylene ether AEO-9 are pre-dissolved in 10 g of propylene glycol and injected into the sand mill by a peristaltic pump at a constant flow rate of 11.5 g / h. The mixture is sand milled for 2 hours. Then, 1 g of aminosilane KH-540 is dispersed in 10 g of propylene glycol and added at a constant flow rate of 5.5 g / h. The mixture is sand milled for another 2 hours to obtain the target slurry.

[0038] Example 3: (1) Dry airflow pre-pulverization: 50 g of tungsten-doped vanadium dioxide powder was placed in an airflow crusher, and argon gas with a purity of 99.9% that had been pre-cooled to 5~15℃ was introduced as the crushing medium. The airflow pressure was controlled at 0.6 MPa, the classifier speed was 5000 rpm, and the crushing was carried out continuously for 20 minutes. Then the machine was stopped for 5 minutes. The total crushing time was 100 minutes, and the pre-refined crushed product was obtained. (2) Initial slurry preparation: The crushed product obtained in step (1) is mixed with 200 g propylene glycol, 15 g ethanol and 15 g deionized water, and 0.5 g 2-methylimidazole and 0.5 g urea are added at the same time. After stirring evenly, the initial slurry is formed. (3) Fine dispersion by sand milling: The initial slurry obtained in step (2) is transferred into a sand mill, and zirconia beads with a diameter of 0.1 mm are used as the grinding medium. The sand milling speed is controlled at 5000~6000 rpm and the initial slurry circulation flow rate is 100~150 mL / min. During the sand milling process, the working temperature of the slurry is maintained at 25~30 ℃ by liquid cooling. First, 5.5 g of polyethylene glycol monolaurate PEG400ML and 7.5 g of K29 type polyvinylpyrrolidone PVP are pre-dissolved in 10 g of propylene glycol and injected into the sand mill at a constant flow rate of 11.5 g / h via a peristaltic pump. The sand milling is carried out for 2 hours. Then, 1 g of pyrophosphate titanate coupling agent KR-38S is added to 11 g of propylene glycol at a uniform flow rate of 3 g / h. The sand milling is continued for 4 hours to obtain the target slurry.

[0039] Comparative Example 1: The difference between Comparative Example 1 and Example 3 is that component A1 urea is not added.

[0040] Comparative Example 2: The difference between Comparative Example 2 and Example 3 is that component A2, 2-methylimidazole, is not added.

[0041] Comparative Example 3: The difference between Comparative Example 3 and Example 3 is that the order of adding additive B (polyethylene glycol monolaurate PEG400ML and K29 ​​type polyvinylpyrrolidone PVP) and additive C (titanate pyrophosphate coupling agent KR-38S) was changed during the sand milling process.

[0042] Comparative Example 4: The difference between Comparative Example 4 and Example 3 is that during the sand milling process, additives B (polyethylene glycol monolaurate PEG400ML and K29 ​​type polyvinylpyrrolidone PVP) and additives C (titanium pyrophosphate coupling agent KR-38S) were added to the slurry all at once at the beginning of the sand milling process, together with additives A (2-methylimidazole and urea).

[0043] Comparative Example 5: The difference between Comparative Example 5 and Example 3 is that it does not use dry airflow pulverization but direct sand milling.

[0044] The final slurry products include the comparative slurries obtained according to Comparative Examples 1-5. The particle size analysis equipment used in this invention is a desktop laser particle size analyzer. This device is based on the principle of laser diffraction, with a testing range of 0.02~2600 μm. It is equipped with an automatic circulating sample feeding system, an ultrasonic dispersion device, and data analysis software, enabling automatic sample dispersion, testing, and real-time acquisition and analysis of particle size distribution data. The specific comparison results of particle size and dispersion stability are shown in Table 1. Table 1: Comparison of Particle Size and Dispersion Stability of Slurry.

[0045]

[0046] Based on the detection results of the laser particle size analyzer (specific detection results are as follows) Figure 3 As shown in the figure, the average particle size of the original powders used in Examples 1-3 and Comparative Examples 1-5 was approximately 6.5 μm. The average particle size of the slurries obtained in Examples 1-3 was in the range of 50-100 nm, as shown in the specific spectra. Figure 4 As shown, the prepared slurry did not settle after 3 months of storage. Specific settling results are as follows: Figure 2 As shown.

[0047] When the pulverized product obtained by dry airflow pre-grinding before sand milling is not supplemented with additive A1 or additive A2, the final slurry prepared from... Figure 5 It can be seen that the final slurry particle size has significantly increased to 150~160 nm, and from Figure 2 Slight powder sedimentation can be observed; when the order or method of adding additives B and C is changed, from Figure 5 It can be seen that the powder particle size further increases, and from Figure 2 Significant sedimentation of the slurry can be observed. In addition, in order to reduce the number of operation steps, if dry air jet milling is not performed before fine dispersion in sand milling, the final slurry will have the largest particle size and significant sedimentation.

Claims

1. A method for dispersing modified vanadium dioxide in a hydrophilic system, characterized in that, Includes the following steps: (1) Dry airflow pre-pulverization: Micron-sized X-VO2 powder is placed in an airflow pulverizer, and pre-cooled inert gas is introduced as the pulverizing medium. The total pulverization time is 50~100 minutes to obtain the pre-refined pulverized product. X in the micron-sized X-VO2 powder is a doping element, and the doping element X is magnesium, tungsten, molybdenum, niobium, terbium, europium, boron or fluorine. The micron-sized X-VO2 powder is M-phase vanadium dioxide with an average particle size of 5~10μm. (2) Initial slurry preparation: The crushed product obtained in step (1) is mixed with hydrophilic solvent S, and additive A is added at the same time. After stirring evenly, an initial slurry is formed. The hydrophilic solvent S includes an organic solvent and deionized water. The organic solvent is a polar organic solvent that does not contain halogens. The mass ratio of hydrophilic solvent S to micron-sized X-VO2 powder is 4~6:

1. Additive A is a combination of reduced A1 component and coordinated A2 component. The A1 component is any one of acetamide, acrylamide, urea, thiourea, thioacetamide, dimethyl sulfone, dicyandiamide or N-hydroxysuccinimide. The A2 component is any one of 18-crown ether-6, 15-crown ether-5, 12-crown ether-4, glucose, fructose, galactose, 2-methylimidazole, 2-aminoimidazole, 1,2,4-triazole or benzotriazole. (3) Fine dispersion by sand milling: The initial slurry obtained in step (2) is added to a sand mill. During the sand milling process, the temperature of the slurry is kept at 25~30℃. Additives B and C are added step by step during the sand milling process. The sand milling is continued for 4~6 hours to obtain a slurry with a particle size of 50~100nm. In step (3) during the fine dispersion process of sand milling, additives B and C are added sequentially in the following manner: additive B is added at a constant rate during the first 2 hours of sand milling, and additive C is added at a constant rate during the remaining time of sand milling until the sand milling is completed; the constant rate of addition is achieved by a peristaltic pump or a flow pump; additives B and C are pre-dissolved in a solvent before addition, and the solvent is an organic solvent in the hydrophilic solvent S; additive B is selected from any two of polyethylene glycol monooleate, polyethylene glycol monolaurate, fatty alcohol polyoxyethylene ether, castor oil polyoxyethylene ether, octylphenol polyoxyethylene ether, polyvinylpyrrolidone, Triton or phenacetin; additive C is selected from any one of the surface modifier components of aminosilane KH-540, epoxysilane KH-561, mercaptosilane KH-590, pyrophosphate titanate coupling agent KR-38S, pyrophosphate titanate coupling agent KR-238S.

2. The method for dispersing modified vanadium dioxide in a hydrophilic system according to claim 1, characterized in that, The inert gas mentioned in step (1) is nitrogen or argon with a purity ≥99.9%; the temperature of the pre-cooled inert gas is 5~15 ℃ and the gas flow pressure is 0.5~0.8MPa.

3. The method for dispersing modified vanadium dioxide in a hydrophilic system according to claim 1, characterized in that, In step (1), the classifier wheel speed of the airflow crusher is 3000~6000 rpm. After continuous crushing for 20 minutes, the machine is stopped for 5 minutes. The total crushing time is 50~100 minutes.

4. The method for dispersing modified vanadium dioxide in a hydrophilic system according to claim 1, characterized in that, In the hydrophilic solvent S, the mass of deionized water is less than 10% of the mass of the organic solvent; The organic solvent is at least one selected from glycerol, propylene glycol, ethylene glycol, diethylene glycol, ethanol, diethylene glycol monomethyl ether, ethylene glycol butyl ether, trimethyl phosphate, triethyl phosphate, or triethanolamine.

5. The method for dispersing modified vanadium dioxide in a hydrophilic system according to claim 1, characterized in that, The amount of component A1 added is 0.5% to 2% of the mass of the micron-sized X-VO2 powder, and the amount of component A2 added is 0.5% to 1% of the mass of the micron-sized X-VO2 powder.

6. The method for dispersing modified vanadium dioxide in a hydrophilic system according to claim 1, characterized in that, The amount of additive B added is 20% to 30% of the mass of the micron-sized X-VO2 powder.

7. The method for dispersing modified vanadium dioxide in a hydrophilic system according to claim 1, characterized in that, The amount of additive C added is 1.5% to 2% of the mass of the micron-sized X-VO2 powder.

8. A slurry prepared by the dispersion method of modified vanadium dioxide in a hydrophilic system according to any one of claims 1-7.

9. The slurry according to claim 8, characterized in that, The average particle size of X-VO2 in the slurry is 50~100nm.

Images