Zero-VOC (volatile organic compound) nano cesium-tungsten bronze dispersion liquid as well as preparation method and application thereof

Abstract

The invention discloses a zero-VOC (volatile organic compound) nano cesium tungsten bronze dispersion liquid as well as a preparation method and application thereof, and relates to the technical field of functional coating materials. The method comprises the following steps: (1) dissolving a tungsten source and a cesium source in deionized water to obtain a mixed solution; (2) adding a reducing agent into the mixed solution, adjusting the pH value of the solution, and carrying out a reduction reaction to obtain a cesium tungsten bronze precursor; (3) adding a flocculating agent into the cesium tungsten bronze precursor, and carrying out flocculation treatment to obtain a flocculation product; (4) carrying out solid-liquid separation and washing purification on the flocculation product to obtain purified cesium tungsten bronze dispersion liquid; (5) carrying out ion exchange treatment on the purified cesium tungsten bronze dispersion liquid; and (6) placing the dispersion liquid subjected to ion exchange in a closed environment, carrying out heat treatment in an inert atmosphere, and cooling to obtain the zero-VOC nano cesium tungsten bronze dispersion liquid. The problems of agglomeration of the nano cesium tungsten bronze material and pollution of the traditional dispersion liquid can be solved.

Description

Technical Field

[0001] This invention relates to the field of functional coating materials technology, and in particular to a zero-VOC nano-cesium tungsten bronze dispersion, its preparation method, and its application. Background Technology

[0002] Nano-cesium tungsten bronze (Cs 0.2-0.33 WO3, as a high-performance near-infrared shielding material, has broad application prospects in fields such as transparent heat-insulating coatings. However, its nanoparticles are prone to agglomeration and are difficult to disperse stably, affecting the final performance. Currently, commercially available cesium tungsten bronze dispersions mostly rely on organic solvents (such as NMP and DMF) and dispersants, resulting in high emissions of volatile organic compounds (VOCs), which not only pollute the environment but also limit its application in fields such as building coatings with strict environmental protection requirements.

[0003] On the other hand, transparent heat-insulating coatings are an effective means of reducing building energy consumption. Their core principle is to selectively block infrared (780-2500nm) and ultraviolet (200-400nm) rays while maintaining high visible light transmittance (typically >70%), thereby reducing heat transfer and achieving energy-saving and cooling effects. While existing coatings offer good heat insulation, most contain organic solvents, leading to VOC emissions and making it difficult to meet stringent environmental regulations (such as VOC content ≤100g / L). Furthermore, poor coating adhesion, low hardness, and poor weather resistance caused by nanoparticle agglomeration are also common problems.

[0004] Therefore, developing a nano-cesium tungsten bronze dispersion with zero VOC, high stability, and the ability to prepare high-performance coatings has become an urgent need in this field. Summary of the Invention

[0005] One of the objectives of this invention is to provide a method for preparing a zero-VOC nano-cesium tungsten bronze dispersion, in order to solve the problems of agglomeration of nano-cesium tungsten bronze materials and pollution in traditional dispersions.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] A method for preparing a zero-VOC nano-cesium tungsten bronze dispersion includes the following steps:

[0008] (1) Dissolve the tungsten source and the cesium source in deionized water to obtain a mixed solution;

[0009] (2) Add a reducing agent to the mixed solution and adjust the pH of the solution to carry out a reduction reaction to obtain (blue) cesium tungsten bronze precursor (such as cesium tungsten bronze colloidal precursor).

[0010] (3) Add flocculant to the cesium tungsten bronze precursor and perform flocculation treatment to obtain flocculated products (such as (blue) cesium tungsten bronze flocculated precipitate).

[0011] (4) The flocculated product is subjected to solid-liquid separation and washing purification to obtain a purified cesium tungsten bronze dispersion;

[0012] (5) The purified cesium tungsten bronze dispersion is subjected to ion exchange treatment to remove impurity ions (such as chloride ions and sodium ions).

[0013] (6) The dispersion after ion exchange is placed in a closed environment and heat-treated under an inert atmosphere. After cooling, a zero-VOC nano-cesium tungsten bronze dispersion (hereinafter referred to as "zero-VOC cesium tungsten bronze dispersion") is obtained.

[0014] In step (1), the tungsten source is sodium tungstate (Na2WO4) or ammonium paratungstate (Na2WO4). (abbreviated as ATP); the cesium source is cesium carbonate (Cs2CO3), cesium nitrate (CsNO3), or cesium chloride (CsCl); the Cs / W ratio is 0.2 to 0.32 (e.g., 0.2, 0.3, or 0.32), that is, the molar ratio of Cs (cesium) to W (tungsten) is (0.2 to 0.32):1 (e.g., 0.2:1, 0.3:1, or 0.32:1).

[0015] The sodium tungstate can be anhydrous or hydrated (such as Na2WO4·2H2O).

[0016] The solid content of the mixed solution is 15%-17%, such as 15% or 17%.

[0017] In step (2), the reducing agent is hydrazine hydrate, ascorbic acid, or a mixture of the two; the acid-base regulator used to adjust the pH of the solution is ammonia water, and the pH range is 8 to 10, for example, adjusting the pH to 8 or 10; the reaction temperature of the reduction reaction is controlled at 50 to 70°C (for example, 50°C, 60°C, or 70°C), and the reaction time is 10 to 14 hours (for example, 10 hours, 12 hours, or 14 hours).

[0018] When hydrazine hydrate is used as a reducing agent, the molar ratio of hydrazine hydrate to tungsten is 1:(5-8), for example 1:5 or 1:8.

[0019] When ascorbic acid is used as a reducing agent, the molar ratio of ascorbic acid to tungsten is (1.5 to 2.5):1, for example, 1.5:1 or 2.5:1.

[0020] When a mixture of hydrazine hydrate and ascorbic acid is used as a reducing agent, the molar ratio of hydrazine hydrate to tungsten is 1:15.6, and the molar ratio of ascorbic acid to tungsten is 2.5:1.

[0021] In step (3), the flocculant is polydiallyl dimethyl ammonium chloride (PDADMAC) or cationic polyacrylamide (CPAM), and its addition amount accounts for 0.05%-0.15% (e.g. 0.05% or 0.15%) of the total mass of the cesium tungsten bronze precursor.

[0022] In step (3), the flocculation treatment includes a step of first performing rapid stirring and then slow stirring. Preferably, the rapid stirring speed is 400-600 r / min (e.g., 400 r / min, 500 r / min, or 600 r / min) and the time is 30-60 s (e.g., 30 s, 40 s, or 60 s); the slow stirring speed is 30-50 r / min (e.g., 30 r / min, 40 r / min, or 50 r / min) and the time is 180-300 s (e.g., 180 s, 240 s, or 300 s).

[0023] In step (4), solid-liquid separation and washing purification include:

[0024] The flocculated product is then filtered to obtain a filter cake.

[0025] The filter cake is mixed with deionized water to obtain a slurry, and the slurry is centrifuged to collect the centrifuged suspension.

[0026] After collecting the centrifuged suspension, the precipitate obtained by centrifugation can be mixed with deionized water and centrifuged again to separate the precipitate and collect the centrifuged suspension. This operation should be performed at least once.

[0027] Preferably, in step (4), the solid content of the slurry is 15%-30% (e.g., 15% or 20% or 30%).

[0028] Preferably, in step (4), the process of mixing the filter cake with deionized water is an emulsification process. After the emulsification process, an emulsion (i.e., slurry) is obtained, and the solid content in the emulsion is controlled at 15%-30% (e.g., 15% or 20% or 30%).

[0029] Furthermore, the specific steps of centrifuging the slurry (emulsion) and collecting the centrifuged suspension include:

[0030] The emulsion was centrifuged, and the centrifuged suspension was collected. The residue was then emulsified again, centrifuged, and the centrifuged suspension was collected. The residue was then emulsified again, centrifuged, and the centrifuged suspension was collected. These three collected centrifuged suspensions were used together as the purified cesium tungsten bronze dispersion.

[0031] In step (5), the ion exchange treatment is as follows: the purified cesium tungsten bronze dispersion is passed through an ion exchange resin column to remove impurity ions (such as chloride ions and sodium ions) to obtain the ion-exchanged dispersion.

[0032] Preferably, in step (5), after obtaining the ion-exchange dispersion, the method further includes: concentrating the ion-exchange dispersion and adjusting the solid content of cesium tungsten bronze therein to 20%-30% (e.g., 20% or 25% or 30%).

[0033] In step (6), the dispersion after ion exchange is first adjusted to pH 7-9 (e.g., 7, 8, or 9); the heat treatment under an inert atmosphere includes: introducing an inert gas (e.g., nitrogen or argon) into a closed environment to replace the air, so that the oxygen content is below 100 ppm, and then holding it at 190-210℃ (e.g., 190℃, 200℃, or 210℃) for 10-12 hours (e.g., 10 hours, 11 hours, or 12 hours).

[0034] The sealed environment can be provided by an autoclave, such as an autoclave with a PTFE liner or a ceramic liner.

[0035] The second objective of this invention is to provide a zero-VOC nano-cesium tungsten bronze dispersion, which is prepared by the method described above.

[0036] The zero-VOC nano-cesium tungsten bronze dispersion (suspension) has the following characteristics:

[0037] The cesium tungsten bronze in the cesium tungsten bronze dispersion has a crystal form of Cs. 0.2 WO3 Cs 0.3 WO3, Cs 0.32 One or more of WO3; by mass fraction, the solid content (solid content) of cesium tungsten bronze is 20-30%; the average particle size is ≤50nm; the pH value is 7-9; the static stability is greater than 180 days (i.e., no sedimentation after 180 days); the VOC content is 0.

[0038] A third objective of this invention is to provide a transparent heat-insulating coating, comprising the following components by weight:

[0039] 25 to 35 parts (e.g., 25, 30, or 35 parts) of zero-VOC nano-cesium tungsten bronze dispersion;

[0040] 20 to 30 parts (e.g., 20, 25, or 30 parts) of silica sol;

[0041] 10 to 20 parts (e.g., 10 or 20 parts) of silane coupling agent;

[0042] 15 to 30 parts (e.g., 15, 20, or 30 parts) of deionized water.

[0043] As a preferred embodiment, the transparent heat-insulating coating comprises, by weight, the following components: 35 parts of zero-VOC nano-cesium tungsten bronze dispersion; 20 parts of silica sol; 10 parts of silane coupling agent (such as KH-550); and 30 parts of deionized water.

[0044] As a preferred embodiment, the transparent heat-insulating coating comprises, by weight, the following components: 25 parts of zero-VOC nano-cesium tungsten bronze dispersion; 30 parts of silica sol; 20 parts of silane coupling agent (such as KH-570); and 15 parts of deionized water.

[0045] As a preferred embodiment, the transparent heat-insulating coating comprises, by weight, the following components: 30 parts of zero-VOC nano-cesium tungsten bronze dispersion; 25 parts of silica sol; 20 parts of silane coupling agent (such as 10 parts of KH-550 and 10 parts of KH-570); and 20 parts of deionized water.

[0046] Preferably, the silica sol contains 15% to 20% silica by mass (e.g., 15%, 18%, or 20%), and its average particle size is ≤20 nm; the silica sol is a zero-VOC silica sol.

[0047] Preferably, the silane coupling agent is at least one of KH-550, KH-560, and KH-570.

[0048] This invention uses zero-VOC nano-cesium tungsten bronze (Cs) x Using WO3 suspension (dispersion) as the heat insulation medium filler and nano silica sol (silica sol) as the film-forming substance to prepare transparent heat insulation coating, it improves the problems of poor adhesion, poor hardness, poor weather resistance and VOC emission of traditional coatings.

[0049] The fourth objective of this invention is to provide a heat-insulating glass, wherein the surface of the heat-insulating glass is coated with the transparent heat-insulating coating described above.

[0050] The fifth objective of this invention is to provide a method for preparing heat-insulating glass, which includes the following steps:

[0051] The transparent heat-insulating coating is applied to the surface of a glass substrate (e.g., by spin coating, curtain coating, or spray coating, wherein the spray gun diameter is 0.8-1.0 mm) to form a wet film (thickness < 50 μm).

[0052] The glass substrate coated with a wet film is cured under an inert atmosphere (such as nitrogen).

[0053] The curing process is a programmed temperature curing process. Specifically, the programmed temperature curing process includes: first, treating at 40-60℃ (e.g., 40℃, 50℃, or 60℃) for 30-60 minutes (e.g., 30min, 40min, or 60min) to achieve uniform film formation and prevent cracking; then treating at 70-100℃ (e.g., 70℃, 80℃, or 100℃) for 30-60 minutes (e.g., 30min, 50min, or 60min) to accelerate solvent evaporation; and finally treating at 160-280℃ (e.g., 160℃, 220℃, or 280℃) for 20-40 minutes (e.g., 20min, 30min, or 40min) to improve density and hardness through annealing.

[0054] This invention successfully prepared a zero-VOC, highly stable nano-cesium tungsten bronze dispersion using a co-precipitation-hydrothermal combined technology. This method eliminates the grinding steps and organic solvents in traditional processes. Through ingenious process design, it not only completely eliminates VOC emissions but also overcomes the technical bottleneck of sacrificing stability in water-based dispersion systems, achieving an ultra-long stability period of over 180 days without sedimentation. At the same time, a deep purification process effectively removes various impurity ions (such as chloride and sodium ions), ultimately obtaining a high-purity, high-performance dispersion product. The entire process is environmentally friendly and simple, perfectly meeting the requirements of green chemistry and sustainable development. This provides key technical support for the large-scale application of this material in fields with stringent environmental requirements, such as building energy conservation and automotive glass.

[0055] Furthermore, this invention also utilizes zero-VOC nano-cesium tungsten bronze (Cs) x Using WO3 suspension (dispersion) as the heat insulation medium and nano-silica sol (silica sol) as the film-forming substance, a high-performance transparent heat insulation coating has been successfully prepared. This fundamentally solves the problems of high VOC emissions, weak adhesion, insufficient hardness, and poor weather resistance of traditional coatings. This coating not only achieves zero VOC emissions, completely eliminating the harm of volatile organic compounds to human health and the environment, but also has a solar heat blocking rate of >90% in the 780-2500 nm wavelength band (infrared region), exhibiting excellent spectral selective heat insulation characteristics. At the same time, the visible light transmittance is >80% and the haze is <1%, perfectly balancing the needs of building energy conservation and natural lighting, demonstrating good optical controllability and practical application value. Attached Figure Description

[0056] Figure 1 The image shows the XRD pattern of cesium tungsten bronze in Example 1, with a crystal form of Cs. 0.2 WO3;

[0057] Figure 2 The image shows the XRD pattern of cesium tungsten bronze in Example 2, with a crystal form of Cs. 0.3 WO3;

[0058] Figure 3 The image shows the XRD pattern of cesium tungsten bronze in Example 3, with a crystal form of Cs. 0.32 WO3;

[0059] Figure 4 The image shows the XRD pattern of cesium tungsten bronze in Example 4, with a crystal form of Cs. 0.32 WO3;

[0060] Figure 5 The image shows the XRD pattern of cesium tungsten bronze in Example 5, with a crystal form of Cs. 0.32 WO3;

[0061] Figure 6 This is a particle size distribution diagram of the cesium tungsten bronze dispersion in Example 6;

[0062] Figure 7 This is a particle size distribution diagram of the cesium tungsten bronze dispersion in Example 7;

[0063] Figure 8 This is a particle size distribution diagram of the cesium tungsten bronze dispersion in Example 8;

[0064] Figure 9 The particle size distribution diagram of the cesium tungsten bronze dispersion in Comparative Example 4 is shown. Detailed Implementation

[0065] To facilitate understanding by those skilled in the art, the present invention will be further described below with reference to embodiments. The content mentioned in the embodiments is not intended to limit the present invention. It should be noted in advance that the following embodiments were completed in a laboratory. Those skilled in the art should understand that the amounts of each component given in the embodiments only represent the ratio between the components, and are not specific limitations.

[0066] Example 1

[0067] Step 1: Accurately weigh 34.2g (0.105mol) of Cs2CO3 powder and 329.9g (1mol) of Na2WO4·2H2O, and dissolve them in 1500ml (17% solid content) of deionized water.

[0068] Step 2: Add 25g of hydrazine hydrate (40%) to the mixed solution from Step 1 (the molar ratio of hydrazine hydrate to tungsten is 1:5), adjust the pH to 8 with ammonia, and react at 50℃ for 14h to obtain the blue cesium tungsten bronze precursor.

[0069] Step 3: Add 1.2g of PDADMAC (molecular weight greater than 500,000) to the cesium tungsten bronze precursor (the percentage of its addition is 0.05% of the total mass of the cesium tungsten bronze precursor), stir at 600r / min for 30s, and then stir at 30r / min for 300s to obtain flocculated precipitate of the cesium tungsten bronze precursor.

[0070] Step 4: Flocculate and precipitate the cesium tungsten bronze precursor and filter it to obtain a filter cake. Emulsify the filter cake in 1000ml of water and fine-tune the amount of deionized water to control the solid content to about 15%.

[0071] Step 5: Centrifuge the emulsion and collect the centrifuged suspension; emulsify the residue again, centrifuge, and collect the centrifuged suspension; emulsify the residue again, centrifuge, and collect the centrifuged suspension; collect the centrifuged residue for other uses; mix the three collected centrifuged suspensions and feed them into an ion exchange column to remove Na from the suspension. + and Cl - The solids were concentrated to 20% by ultrafiltration to obtain a cesium tungsten bronze precursor suspension with a solids content of 20%.

[0072] Step 6: Adjust the pH of the centrifuged suspension to 7 with ammonia water and then transfer it into a PTFE-lined autoclave.

[0073] Step 7: Bubble 99% N2 gas into the autoclave for 30 minutes to reduce the oxygen content in the autoclave to below 100 ppm. Control the autoclave temperature at 190℃ and maintain the temperature for 12 hours. Cool to obtain a zero-VOC cesium tungsten bronze dispersion.

[0074] Example 2

[0075] Step 1: Accurately weigh 50.5g (0.155mol) of Cs2CO3 powder and 329.9g (1mol) of Na2WO4·2H2O, and dissolve them in 1500ml (17% solid content) of deionized water.

[0076] Step 2: Add 16g of hydrazine hydrate (40%) to the mixed solution from Step 1 (the molar ratio of hydrazine hydrate to tungsten is 1:8), adjust the pH to 10 with ammonia, and react at 70℃ for 10h to obtain the blue cesium tungsten bronze precursor.

[0077] Step 3: Add 3.6g of PDADMAC (molecular weight greater than 500,000) to the cesium tungsten bronze precursor (the percentage of its addition is 0.15% of the total mass of the cesium tungsten bronze precursor), stir at 400r / min for 60s, and then stir at 50r / min for 180s to obtain flocculated precipitate of the cesium tungsten bronze precursor.

[0078] Step 4: Flocculate and precipitate the cesium tungsten bronze precursor and filter it to obtain a filter cake. Emulsify the filter cake in 1000ml of water and adjust the amount of deionized water to control the solid content to about 30%.

[0079] Step 5: Centrifuge the emulsion and collect the centrifuged suspension; emulsify the residue again, centrifuge, and collect the centrifuged suspension; emulsify the residue again, centrifuge, and collect the centrifuged suspension; collect the centrifuged residue for other uses; mix the three collected centrifuged suspensions and feed them into an ion exchange column to remove Na from the suspension. + and Cl - The solids were concentrated to 30% by ultrafiltration to obtain a cesium tungsten bronze precursor suspension with a solids content of 30%.

[0080] Step 6: Adjust the pH of the centrifuged suspension to 9 with ammonia water and then transfer it into a ceramic-lined autoclave.

[0081] Step 7: Bubble 99% Ar gas into the autoclave for 10 minutes to reduce the oxygen content in the autoclave to below 100 ppm. Control the autoclave temperature at 210℃ and maintain the temperature for 10 hours. Cool to obtain a zero-VOC cesium tungsten bronze dispersion.

[0082] Example 3

[0083] Step 1: Accurately weigh 55.6g (0.33mol) of CsCl crystals and 262.4g (1mol) of ATP, and dissolve them in 1500ml (15% solid content) of deionized water.

[0084] Step 2: Add 264g of ascorbic acid (molar ratio of ascorbic acid to tungsten is 1.5:1) to the mixed solution in Step 1, adjust the pH to 8 with ammonia, and react at 50℃ for 14h to obtain the blue cesium tungsten bronze precursor.

[0085] Step 3: Add 2.4g of PDADMAC (molecular weight greater than 500,000) to the cesium tungsten bronze precursor (the percentage of its addition is 0.05% of the total mass of the cesium tungsten bronze precursor), stir at 500r / min for 40s, and then stir at 40r / min for 240s to obtain flocculated precipitate of the cesium tungsten bronze precursor.

[0086] Step 4: Flocculate and precipitate the cesium tungsten bronze precursor and filter it to obtain a filter cake. Emulsify the filter cake in 1000ml of water and fine-tune the amount of deionized water to control the solid content to about 20%.

[0087] Step 5: Centrifuge the emulsion and collect the centrifuged suspension; emulsify the residue again, centrifuge, and collect the centrifuged suspension; emulsify the residue again, centrifuge, and collect the centrifuged suspension; collect the centrifuged residue for other uses; mix the three collected centrifuged suspensions and feed them into an ion exchange column to remove Na from the suspension. + and Cl - The solids were concentrated to 25% by ultrafiltration to obtain a cesium tungsten bronze precursor suspension with a solids content of 25%.

[0088] Step 6: Adjust the pH of the centrifuged suspension to 8 with ammonia water and then transfer it into a PTFE-lined autoclave.

[0089] Step 7: Bubble 99% N2 gas into the autoclave for 20 minutes to reduce the oxygen content in the autoclave to below 100 ppm. Control the autoclave temperature at 200℃ and maintain the temperature for 11 hours. Cool to obtain a zero-VOC cesium tungsten bronze dispersion.

[0090] Example 4

[0091] Step 1: Accurately weigh 64.3g (0.33mol) of CsNO3 crystals and 262.4g (1mol) of ATP, and dissolve them in 1500ml (15% solid content) of deionized water.

[0092] Step 2: Add 440g of ascorbic acid (molar ratio of ascorbic acid to tungsten is 2.5:1) to the mixed solution in Step 1, adjust the pH to 8 with ammonia, and react at 60℃ for 12h to obtain the blue cesium tungsten bronze precursor.

[0093] Step 3: Add 2.4g of PDADMAC (molecular weight greater than 500,000) to the cesium tungsten bronze precursor (the percentage of its addition is 0.05% of the total mass of the cesium tungsten bronze precursor), stir at 500r / min for 40s, and then stir at 40r / min for 240s to obtain flocculated precipitate of the cesium tungsten bronze precursor.

[0094] Step 4: Flocculate and precipitate the cesium tungsten bronze precursor and filter it to obtain a filter cake. Emulsify the filter cake in 1000ml of water and fine-tune the amount of deionized water to control the solid content to about 20%.

[0095] Step 5: Centrifuge the emulsion and collect the centrifuged suspension; emulsify the residue again, centrifuge, and collect the centrifuged suspension; emulsify the residue again, centrifuge, and collect the centrifuged suspension; collect the centrifuged residue for other uses; mix the three collected centrifuged suspensions and feed them into an ion exchange column to remove Na from the suspension. + and Cl - The solids were concentrated to 20% by ultrafiltration to obtain a cesium tungsten bronze precursor suspension with a solids content of 20%.

[0096] Step 6: Adjust the pH of the centrifuged suspension to 8 with ammonia water and then transfer it into a PTFE-lined autoclave.

[0097] Step 7: Bubble 99% N2 gas into the autoclave for 20 minutes to reduce the oxygen content in the autoclave to below 100 ppm. Control the autoclave temperature at 200℃ and maintain the temperature for 11 hours. Cool to obtain a zero-VOC cesium tungsten bronze dispersion.

[0098] Example 5

[0099] Step 1: Accurately weigh 64.3g (0.33mol) of CsNO3 crystals and 262.4g (1mol) of ATP, and dissolve them in 1500ml (15% solid content) of deionized water.

[0100] Step 2: Add 220g of ascorbic acid (molar ratio of ascorbic acid to tungsten is 2.5:1) and 8g of hydrazine (40%) (molar ratio of hydrazine to tungsten is 1:15.6) to the mixed solution in Step 1. Adjust the pH to 8 with ammonia water and react at 60℃ for 12h to obtain the blue cesium tungsten bronze precursor.

[0101] Step 3: Add 2.4g of PDADMAC (molecular weight greater than 500,000) to the cesium tungsten bronze precursor (the percentage of its addition is 0.05% of the total mass of the cesium tungsten bronze precursor), stir at 500r / min for 40s, and then stir at 40r / min for 240s to obtain flocculated precipitate of the cesium tungsten bronze precursor.

[0102] Step 4: Flocculate and precipitate the cesium tungsten bronze precursor and filter it to obtain a filter cake. Emulsify the filter cake in 1000ml of water and fine-tune the amount of deionized water to control the solid content to about 20%.

[0103] Step 5: Centrifuge the emulsion and collect the centrifuged suspension; emulsify the residue again, centrifuge, and collect the centrifuged suspension; emulsify the residue again, centrifuge, and collect the centrifuged suspension; collect the centrifuged residue for other uses; mix the three collected centrifuged suspensions and feed them into an ion exchange column to remove Na from the suspension. + and Cl - The solids were concentrated to 20% by ultrafiltration to obtain a cesium tungsten bronze precursor suspension with a solids content of 20%.

[0104] Step 6: Adjust the pH of the centrifuged suspension to 8 with ammonia water and then transfer it into a PTFE-lined autoclave.

[0105] Step 7: Bubble 99% N2 gas into the autoclave for 20 minutes to reduce the oxygen content in the autoclave to below 100 ppm. Control the autoclave temperature at 200℃ and maintain the temperature for 11 hours. Cool to obtain a zero-VOC cesium tungsten bronze dispersion.

[0106] The environmental performance of the zero-VOC cesium tungsten bronze dispersions prepared in Examples 1-5 is shown in Table 1 below.

[0107] Table 1. Environmental performance of cesium tungsten suspensions in Examples 1-5

[0108]

[0109] As can be seen from Table 1, no VOCs were detected in the cesium tungsten bronze suspensions (cesium tungsten bronze dispersions) prepared in Examples 1-5, which are zero-VOC cesium tungsten bronze suspensions.

[0110] Comparative Example 1

[0111] Step 1: Accurately weigh 34.2g (0.105mol) of Cs2CO3 powder and 329.9g (1mol) of Na2WO4·2H2O, and dissolve them in 1500ml (17% solid content) of deionized water.

[0112] Step 2: Add 8g of hydrazine hydrate (40%) to the mixed solution from Step 1 (the molar ratio of hydrazine hydrate to tungsten is 1:15.6), adjust the pH to 8 with ammonia, and react at 50℃ for 14h to obtain the blue cesium tungsten bronze precursor.

[0113] Step 3: Add 1.2g of PDADMAC (molecular weight greater than 500,000) to the cesium tungsten bronze precursor (the percentage of its addition is 0.05% of the total mass of the cesium tungsten bronze precursor), stir at 600r / min for 30s, and then stir at 30r / min for 300s to obtain flocculated precipitate of the cesium tungsten bronze precursor.

[0114] Step 4: Flocculate and precipitate the cesium tungsten bronze precursor and filter it to obtain a filter cake. Emulsify the filter cake in 1000ml of water and fine-tune the amount of deionized water to control the solid content to about 15%.

[0115] Step 5: Centrifuge the emulsion and collect the centrifuged suspension; emulsify the residue again, centrifuge, and collect the centrifuged suspension; emulsify the residue again, centrifuge, and collect the centrifuged suspension; collect the centrifuged residue for other uses; mix the three collected centrifuged suspensions and feed them into an ion exchange column to remove Na from the suspension. + and Cl - The solids were concentrated to 20% by ultrafiltration to obtain a cesium tungsten bronze precursor suspension with a solids content of 20%.

[0116] Step 6: Adjust the pH of the centrifuged suspension to 7 with ammonia water and then transfer it into a PTFE-lined autoclave.

[0117] Step 7: Bubble 99% N2 gas into the autoclave for 30 minutes to reduce the oxygen content in the autoclave to below 100 ppm. Control the autoclave temperature at 190℃ and maintain the temperature for 12 hours. Cool to obtain a zero-VOC cesium tungsten bronze dispersion.

[0118] Comparative Example 2

[0119] Step 1: Accurately weigh 33g (0.1mol) of Cs2CO3 powder and 330g (1mol) of Na2WO4·2H2O, and dissolve them in 1500ml (17% solid content) of deionized water.

[0120] Step 2: Add 8g of hydrazine hydrate (80%) to the mixed solution from Step 1 (the molar ratio of hydrazine hydrate to tungsten is 1:7.8), adjust the pH to 8 with ammonia, and react at 50℃ for 14h to obtain the blue cesium tungsten bronze precursor.

[0121] Step 3: Add 1.2g of PDADMAC (molecular weight greater than 500,000) to the cesium tungsten bronze precursor (the percentage of its addition is 0.05% of the total mass of the cesium tungsten bronze precursor), stir at 600r / min for 30s, and then stir at 30r / min for 300s to obtain flocculated precipitate of the cesium tungsten bronze precursor.

[0122] Step 4: Flocculate and precipitate the cesium tungsten bronze precursor and filter it to obtain a filter cake. Emulsify the filter cake in 1000ml of water and fine-tune the amount of deionized water to control the solid content to about 15%.

[0123] Step 5: Feed the emulsion into an ion exchange column to remove Na from the suspension. + and Cl - The solids were concentrated to 20% by ultrafiltration to obtain a cesium tungsten bronze precursor suspension with a solids content of 20%.

[0124] Step 6: Adjust the pH of the centrifuged suspension to 7 with ammonia water and then transfer it into a PTFE-lined autoclave.

[0125] Step 7: Bubble 99% N2 gas into the autoclave for 30 minutes to reduce the oxygen content in the autoclave to below 100 ppm. Control the autoclave temperature at 190℃ and maintain the temperature for 12 hours. Cool to obtain a zero-VOC cesium tungsten bronze dispersion.

[0126] Comparative Example 3

[0127] Step 1: Accurately weigh 33g (0.1mol) of Cs2CO3 powder and 330g (1mol) of Na2WO4·2H2O, and dissolve them in 1500ml (17% solid content) of deionized water.

[0128] Step 2: Add 8g of hydrazine hydrate (80%) to the mixed solution from Step 1 (the molar ratio of hydrazine hydrate to tungsten is 1:7.8), adjust the pH to 8 with ammonia, and react at 50℃ for 14h to obtain the blue cesium tungsten bronze precursor.

[0129] Step 3: Add 1.2g of PDADMAC (molecular weight greater than 500,000) to the cesium tungsten bronze precursor (the percentage of its addition is 0.05% of the total mass of the cesium tungsten bronze precursor), stir at 600r / min for 30s, and then stir at 30r / min for 300s to obtain flocculated precipitate of the cesium tungsten bronze precursor.

[0130] Step 4: Flocculate and precipitate the cesium tungsten bronze precursor and filter it to obtain a filter cake. Emulsify the filter cake in 1000ml of water and fine-tune the amount of deionized water to control the solid content to about 15%.

[0131] Step 5: Centrifuge the emulsion and collect the centrifuged suspension; emulsify the residue again, centrifuge, and collect the centrifuged suspension; emulsify the residue again, centrifuge, and collect the centrifuged suspension; collect the centrifuged residue for other uses; mix the three collected centrifuged suspensions and feed them into an ion exchange column to remove Na from the suspension. + and Cl - The solids were concentrated to 20% by ultrafiltration to obtain a cesium tungsten bronze precursor suspension with a solids content of 20%.

[0132] Step 6: Adjust the pH of the centrifuged suspension to 7 with ammonia water and then transfer it into a PTFE-lined autoclave.

[0133] Step 7: Bubble 99% N2 gas into the autoclave for 30 minutes to reduce the oxygen content in the autoclave to below 100 ppm. Control the autoclave temperature at 240℃ and maintain the temperature for 12 hours. Cool to obtain a zero-VOC cesium tungsten bronze dispersion.

[0134] The comparison results of appearance and stability of Examples 1-5 and Comparative Examples 1-3 are shown in Table 2 below.

[0135] Table 2 Comparison of appearance and stability between Examples 1-5 and Comparative Examples 1-3

[0136]

[0137] Comparative Example 1 shows that the cesium tungsten bronze dispersion is bluish-gray in color, mainly due to insufficient reducing agent, resulting in the formation of tungsten trioxide, increased particle size, and decreased stability; sedimentation began after 20 days. Comparative Example 2 shows that the lack of emulsification and centrifugation before adding the cesium tungsten dispersion to the reactor led to the entry of large particles, which agglomerated during the reaction, reaching a particle size of 180.10 nm, accelerating precipitation; sedimentation began to appear one day after synthesis. Comparative Example 3, due to excessively high holding temperature, resulted in grain growth reaching 88.38 nm, accelerating precipitation, decreasing stability, and sedimentation began after 15 days.

[0138] Example 6

[0139] I. Preparation of Zero-VOC Cesium Tungsten Bronze Dispersion (Cesium Tungsten Content 20%, Cs 0.2 WO3):

[0140] Step 1: Accurately weigh 34.2g (0.105mol) of Cs2CO3 powder and 329.9g (1mol) of Na2WO4·2H2O, and dissolve them in 1500ml (17% solid content) of deionized water.

[0141] Step 2: Add 25g of hydrazine hydrate (40%) to the mixed solution from Step 1 (the molar ratio of hydrazine hydrate to tungsten is 1:5), adjust the pH to 8 with ammonia, and react at 50℃ for 14h to obtain the blue cesium tungsten bronze precursor.

[0142] Step 3: Add 1.2g of PDADMAC (molecular weight greater than 500,000) to the cesium tungsten bronze precursor (the percentage of its addition is 0.05% of the total mass of the cesium tungsten bronze precursor), stir at 600r / min for 30s, and then stir at 30r / min for 300s to obtain flocculated precipitate of the cesium tungsten bronze precursor.

[0143] Step 4: Flocculate and precipitate the cesium tungsten bronze precursor and filter it to obtain a filter cake. Emulsify the filter cake in 1000ml of water and fine-tune the amount of deionized water to control the solid content to about 15%.

[0144] Step 5: Centrifuge the emulsion and collect the centrifuged suspension; emulsify the residue again, centrifuge, and collect the centrifuged suspension; emulsify the residue again, centrifuge, and collect the centrifuged suspension; collect the centrifuged residue for other uses; mix the three collected centrifuged suspensions and feed them into an ion exchange column to remove Na from the suspension. + and Cl - The solids were concentrated to 20% by ultrafiltration to obtain a cesium tungsten bronze precursor suspension with a solids content of 20%.

[0145] Step 6: Adjust the pH of the centrifuged suspension to 7 with ammonia water and then transfer it into a PTFE-lined autoclave.

[0146] Step 7: Bubble 99% N2 gas into the autoclave for 30 minutes to reduce the oxygen content in the autoclave to below 100 ppm. Control the autoclave temperature at 190℃ and maintain the temperature for 12 hours. Cool to obtain a zero-VOC cesium tungsten bronze dispersion.

[0147] II. Preparation of Zero-VOC Cesium Tungsten Bronze Oxide Transparent Thermal Insulation Coating:

[0148] Accurately weigh 35g of the zero-VOC cesium tungsten bronze dispersion prepared in this embodiment, 20g of SiO2 sol with an effective content of 15% (average particle size ≤20nm), 10g of silane coupling agent (KH550), and 30g of deionized water into a single-necked flask, and stir to mix evenly.

[0149] III. Preparation of glass surface coating:

[0150] A transparent heat-insulating coating is applied to the glass surface by spin coating and cured in a high-temperature furnace. N2 is introduced into the high-temperature furnace, and the film is first formed at 40°C for 60 minutes, then dried at 70°C for 60 minutes, and finally annealed at 280°C for 20 minutes to obtain a cesium tungsten heat-insulating glass coating.

[0151] Example 7

[0152] I. Preparation of Zero-VOC Cesium Tungsten Bronze Dispersion (Cesium Tungsten content 30%, Cs 0.3 WO3):

[0153] Step 1: Accurately weigh 50.5g (0.155mol) of Cs2CO3 powder and 329.9g (1mol) of Na2WO4·2H2O, and dissolve them in 1500ml (17% solid content) of deionized water.

[0154] Step 2: Add 16g of hydrazine hydrate (40%) to the mixed solution from Step 1 (the molar ratio of hydrazine hydrate to tungsten is 1:8), adjust the pH to 10 with ammonia, and react at 70℃ for 10h to obtain the blue cesium tungsten bronze precursor.

[0155] Step 3: Add 3.6g of PDADMAC (molecular weight greater than 500,000) to the cesium tungsten bronze precursor (the percentage of its addition is 0.15% of the total mass of the cesium tungsten bronze precursor), stir at 400r / min for 60s, and then stir at 50r / min for 180s to obtain flocculated precipitate of the cesium tungsten bronze precursor.

[0156] Step 4: Flocculate and precipitate the cesium tungsten bronze precursor and filter it to obtain a filter cake. Emulsify the filter cake in 1000ml of water and adjust the amount of deionized water to control the solid content to about 30%.

[0157] Step 5: Centrifuge the emulsion and collect the centrifuged suspension; emulsify the residue again, centrifuge, and collect the centrifuged suspension; emulsify the residue again, centrifuge, and collect the centrifuged suspension; collect the centrifuged residue for other uses; mix the three collected centrifuged suspensions and feed them into an ion exchange column to remove Na from the suspension. + and Cl - The solids were concentrated to 30% by ultrafiltration to obtain a cesium tungsten bronze precursor suspension with a solids content of 30%.

[0158] Step 6: Adjust the pH of the centrifuged suspension to 9 with ammonia water and then transfer it into a ceramic-lined autoclave.

[0159] Step 7: Bubble 99% Ar gas into the autoclave for 10 minutes to reduce the oxygen content in the autoclave to below 100 ppm. Control the autoclave temperature at 210℃ and maintain the temperature for 10 hours. Cool to obtain a zero-VOC cesium tungsten bronze dispersion.

[0160] II. Preparation of Zero-VOC Cesium Tungsten Bronze Oxide Transparent Thermal Insulation Coating:

[0161] Accurately weigh 25g of the zero-VOC cesium tungsten bronze dispersion prepared in this embodiment, 30g of SiO2 sol with an effective content of 20% (average particle size ≤20nm), 20g of silane coupling agent (KH570), and 15g of deionized water into a single-necked flask, and stir to mix evenly.

[0162] III. Preparation of glass surface coating:

[0163] A transparent heat-insulating coating is applied to the glass surface by spin coating and cured in a high-temperature furnace. N2 is introduced into the high-temperature furnace, and the film is first formed at 60°C for 30 minutes, then dried at 100°C for 30 minutes, and finally annealed at 160°C for 40 minutes to obtain a cesium tungsten heat-insulating glass coating.

[0164] Example 8

[0165] I. Preparation of Zero-VOC Cesium Tungsten Bronze Dispersion (Cesium Tungsten content 25%, Cs 0.32 WO3):

[0166] Step 1: Accurately weigh 55.6g (0.33mol) of CsCl crystals and 262.4g (1mol) of ATP, and dissolve them in 1500ml (15% solid content) of deionized water.

[0167] Step 2: Add 264g of ascorbic acid (molar ratio of ascorbic acid to tungsten is 1.5:1) to the mixed solution in Step 1, adjust the pH to 8 with ammonia, and react at 50℃ for 14h to obtain the blue cesium tungsten bronze precursor.

[0168] Step 3: Add 2.4g of PDADMAC (molecular weight greater than 500,000) to the cesium tungsten bronze precursor (the percentage of its addition is 0.05% of the total mass of the cesium tungsten bronze precursor), stir at 500r / min for 40s, and then stir at 40r / min for 240s to obtain flocculated precipitate of the cesium tungsten bronze precursor.

[0169] Step 4: Flocculate and precipitate the cesium tungsten bronze precursor and filter it to obtain a filter cake. Emulsify the filter cake in 1000ml of water and fine-tune the amount of deionized water to control the solid content to about 20%.

[0170] Step 5: Centrifuge the emulsion and collect the centrifuged suspension; emulsify the residue again, centrifuge, and collect the centrifuged suspension; emulsify the residue again, centrifuge, and collect the centrifuged suspension; collect the centrifuged residue for other uses; mix the three collected centrifuged suspensions and feed them into an ion exchange column to remove Na from the suspension. + and Cl - The solids were concentrated to 25% by ultrafiltration to obtain a cesium tungsten bronze precursor suspension with a solids content of 25%.

[0171] Step 6: Adjust the pH of the centrifuged suspension to 8 with ammonia water and then transfer it into a PTFE-lined autoclave.

[0172] Step 7: Bubble 99% N2 gas into the autoclave for 20 minutes to reduce the oxygen content in the autoclave to below 100 ppm. Control the autoclave temperature at 200℃ and hold for 11 hours. Cool to obtain a zero-VOC cesium tungsten bronze dispersion.

[0173] II. Preparation of Zero-VOC Cesium Tungsten Bronze Oxide Transparent Thermal Insulation Coating:

[0174] Accurately weigh 30g of the zero-VOC cesium tungsten bronze dispersion prepared in this embodiment, 25g of SiO2 sol with an effective content of 18% (average particle size ≤20nm), 10g of silane coupling agent KH550, 10g of KH570, and 20g of deionized water into a single-necked flask, and stir to mix evenly.

[0175] III. Preparation of glass surface coating:

[0176] A transparent heat-insulating coating is applied to the glass surface by spin coating and cured in a high-temperature furnace. N2 is introduced into the high-temperature furnace, and the film is first formed at 50°C for 40 minutes, then dried at 80°C for 50 minutes, and finally annealed at 220°C for 30 minutes to obtain a cesium tungsten heat-insulating glass coating.

[0177] Comparative Example 4

[0178] I. Preparation of Zero-VOC Cesium Tungsten Bronze Dispersion (Cesium Tungsten Content 20%, Cs 0.2 WO3):

[0179] Step 1: Accurately weigh 33g (0.1mol) of Cs2CO3 powder and 330g (1mol) of Na2WO4·2H2O, and dissolve them in 1500ml (17% solid content) of deionized water.

[0180] Step 2: Add 8g of hydrazine hydrate (80%) to the mixed solution from Step 1 (the molar ratio of hydrazine hydrate to tungsten is 1:7.8), adjust the pH to 8 with ammonia, and react at 50℃ for 14h to obtain the blue cesium tungsten bronze precursor.

[0181] Step 3: Add 1.2g of PDADMAC (molecular weight greater than 500,000) to the cesium tungsten bronze precursor (the percentage of its addition is 0.05% of the total mass of the cesium tungsten bronze precursor), stir at 600r / min for 30s, and then stir at 30r / min for 300s to obtain flocculated precipitate of the cesium tungsten bronze precursor.

[0182] Step 4: Flocculate and precipitate the cesium tungsten bronze precursor and filter it to obtain a filter cake. Emulsify the filter cake in 1000ml of water and fine-tune the amount of deionized water to control the solid content to about 15%.

[0183] Step 5: Feed the emulsion into an ion exchange column to remove Na from the suspension. + and Cl - The solids were concentrated to 20% by ultrafiltration to obtain a cesium tungsten bronze precursor suspension with a solids content of 20%.

[0184] Step 6: Adjust the pH of the centrifuged suspension to 7 with ammonia water and then transfer it into a PTFE-lined autoclave.

[0185] Step 7: Bubble 99% N2 gas into the autoclave for 30 minutes to reduce the oxygen content in the autoclave to below 100 ppm. Control the autoclave temperature at 190℃ and maintain the temperature for 12 hours. Cool to obtain a zero-VOC cesium tungsten bronze dispersion.

[0186] II. Preparation of Zero-VOC Cesium Tungsten Bronze Oxide Transparent Thermal Insulation Coating:

[0187] Accurately weigh 35g of the zero-VOC cesium tungsten bronze suspension prepared in this embodiment, 20g of SiO2 sol with an effective content of 15% (average particle size ≤20nm), 10g of silane coupling agent (KH550), and 30g of deionized water into a single-necked flask, and stir to mix evenly.

[0188] III. Preparation of glass surface coating:

[0189] A transparent heat-insulating coating is applied to the glass surface by spin coating and cured in a high-temperature furnace. N2 is introduced into the high-temperature furnace, and the film is first formed at 40°C for 60 minutes, then dried at 70°C for 60 minutes, and finally annealed at 280°C for 40 minutes to obtain a cesium tungsten heat-insulating glass coating.

[0190] Comparative Example 5

[0191] I. Preparation of Zero-VOC Cesium Tungsten Bronze Dispersion (Cesium Tungsten content 30%, Cs 0.3 WO3):

[0192] Step 1: Accurately weigh 50.5g (0.155mol) of Cs2CO3 powder and 329.9g (1mol) of Na2WO4·2H2O, and dissolve them in 1500ml (17% solid content) of deionized water.

[0193] Step 2: Add 16g of hydrazine hydrate (40%) to the mixed solution from Step 1 (the molar ratio of hydrazine hydrate to tungsten is 1:8), adjust the pH to 10 with ammonia, and react at 70℃ for 10h to obtain the blue cesium tungsten bronze precursor.

[0194] Step 3: Add 3.6g of PDADMAC (molecular weight greater than 500,000) to the cesium tungsten bronze precursor (the percentage of its addition is 0.15% of the total mass of the cesium tungsten bronze precursor), stir at 400r / min for 60s, and then stir at 50r / min for 180s to obtain flocculated precipitate of the cesium tungsten bronze precursor.

[0195] Step 4: Flocculate and precipitate the cesium tungsten bronze precursor and filter it to obtain a filter cake. Emulsify the filter cake in 1000ml of water and adjust the amount of deionized water to control the solid content to about 30%.

[0196] Step 5: Centrifuge the emulsion and collect the centrifuged suspension; emulsify the residue again, centrifuge, and collect the centrifuged suspension; emulsify the residue again, centrifuge, and collect the centrifuged suspension; collect the centrifuged residue for other uses; mix the three collected centrifuged suspensions and feed them into an ion exchange column to remove Na from the suspension. + and Cl - The solids were concentrated to 30% by ultrafiltration to obtain a cesium tungsten bronze precursor suspension with a solids content of 30%.

[0197] Step 6: Adjust the pH of the centrifuged suspension to 9 with ammonia water and then transfer it into a ceramic-lined autoclave.

[0198] Step 7: Bubble 99% Ar gas into the autoclave for 10 minutes to reduce the oxygen content in the autoclave to below 100 ppm. Control the autoclave temperature at 210℃ and maintain the temperature for 10 hours. Cool to obtain a zero-VOC cesium tungsten bronze dispersion.

[0199] II. Preparation of Zero-VOC Cesium Tungsten Bronze Oxide Transparent Thermal Insulation Coating:

[0200] Accurately weigh 25g of the zero-VOC cesium tungsten bronze dispersion prepared in this embodiment, 30g of SiO2 sol with an effective content of 20% (average particle size ≤20nm), 20g of silane coupling agent (KH570), and 15g of deionized water into a single-necked flask, and stir to mix evenly.

[0201] III. Preparation of glass surface coating:

[0202] A transparent heat-insulating coating is applied to the glass surface by spin coating and cured in a high-temperature furnace. N2 is introduced into the high-temperature furnace, and the film-forming reaction is carried out at 60°C for 30 minutes, followed by drying at 100°C for 30 minutes to obtain a cesium tungsten heat-insulating glass coating.

[0203] The environmental performance of the zero-VOC cesium tungsten bronze dispersions prepared in Examples 6-8 is shown in Table 3 below.

[0204] Table 3. Environmental performance of cesium tungsten bronze suspensions in Examples 6-8

[0205]

[0206] The glass coating data of Examples 6-8 and Comparative Examples 4-5 are compared in Table 4 below.

[0207] Table 4. Comparative Analysis of Glass Coating Data from Examples 6-8 and Comparative Examples 4-5

[0208]

[0209] Table 4 shows that the infrared blocking rate and visible light transmittance of Examples 6-8 are both above 90% and above 80%, respectively, the haze is below 0.5%, the adhesion is grade 0 (the highest grade), and the hardness can reach 5H. The average particle size of Comparative Example 4 (see...) Figure 9 It can be observed that the average particle size of the cesium tungsten bronze in Comparative Example 4 reaches over 180 nm, which is much larger than that in Examples 6-8 (below 50 nm) (see...). Figure 6-8 In Comparative Example 4, the coating exhibits a light blue, hazy appearance, with the haze increasing to 1.21%. This is primarily due to the excessively large average particle size, causing diffuse reflection. The hardness also decreases, mainly because the larger particle size leads to uneven coating and a higher probability of defects, thus reducing hardness. In Comparative Example 5, the hardness decreases to 2H, mainly because the drying temperature was too low, resulting in insufficient cross-linking and a decrease in hardness.

[0210] The above embodiments are preferred implementations of the present invention. In addition, the present invention can be implemented in other ways. Any obvious substitutions without departing from the concept of the present technical solution are within the protection scope of the present invention.

Claims

1. A method for preparing a zero-VOC nano-cesium tungsten bronze dispersion, characterized in that, Includes the following steps: (1) Dissolve the tungsten source and the cesium source in deionized water to obtain a mixed solution; (2) Add a reducing agent to the mixed solution and adjust the pH of the solution to carry out a reduction reaction to obtain the cesium tungsten bronze precursor; (3) Add flocculant to the cesium tungsten bronze precursor and perform flocculation treatment to obtain flocculated products; (4) The flocculated product is subjected to solid-liquid separation and washing purification to obtain a purified cesium tungsten bronze dispersion; (5) The purified cesium tungsten bronze dispersion was subjected to ion exchange treatment; (6) The dispersion after ion exchange is placed in a closed environment and heat-treated under an inert atmosphere. After cooling, a zero-VOC nano-cesium tungsten bronze dispersion is obtained.

2. The method for preparing zero-VOC nano-cesium tungsten bronze dispersion according to claim 1, characterized in that, In step (1), The tungsten source is sodium tungstate or ammonium paratungstate; The cesium source is cesium carbonate, cesium nitrate, or cesium chloride; The molar ratio of Cs to W is (0.2–0.32):

1.

3. The method for preparing the zero-VOC nano-cesium tungsten bronze dispersion according to claim 1, characterized in that, In step (2), The reducing agent is hydrazine hydrate, ascorbic acid, or a mixture of the two; The acid-base regulator used to adjust the pH of the solution is ammonia water, and the pH range for adjustment is 8 to 10; The reduction reaction is controlled at a temperature of 50–70°C and a reaction time of 10–14 h.

4. The method for preparing the zero-VOC nano-cesium tungsten bronze dispersion according to claim 1, characterized in that, In step (3), The flocculant is polydiallyldimethylammonium chloride or cationic polyacrylamide, and its addition amount accounts for 0.05-0.15% of the total mass of the cesium tungsten bronze precursor.

5. The method for preparing the zero-VOC nano-cesium tungsten bronze dispersion according to claim 1, characterized in that, The solid-liquid separation and washing purification in step (4) include: The flocculated product is then filtered to obtain a filter cake. The filter cake is mixed with deionized water to obtain a slurry, and the slurry is centrifuged to collect the centrifuged suspension.

6. The method for preparing the zero-VOC nano-cesium tungsten bronze dispersion according to claim 1, characterized in that, In step (6), The heat treatment under an inert atmosphere includes: introducing an inert gas into a sealed environment to replace the air, so that the oxygen content is below 100 ppm, and then holding the heat at 190-210°C for 10-12 hours.

7. A zero-VOC nano-cesium tungsten bronze dispersion, characterized in that: It is prepared by the preparation method described in any one of claims 1-6.

8. A transparent heat-insulating coating, characterized in that, By weight, it includes the following components: 25-35 parts of the zero-VOC nano-cesium tungsten bronze dispersion as described in claim 7; 20-30 parts of silica sol; 10-20 parts of silane coupling agent; 15-30 parts of deionized water.

9. A type of heat-insulating glass, characterized in that, The surface is coated with the transparent heat-insulating coating as described in claim 8.

10. A method for preparing heat-insulating glass as described in claim 9, characterized in that, Includes the following steps: The transparent heat-insulating coating is applied to the surface of a glass substrate to form a wet film; The glass substrate coated with a wet film is cured under an inert atmosphere.

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